xref: /openbsd-src/gnu/usr.bin/perl/regexec.c (revision 7350f337b9e3eb4461d99580e625c7ef148d107c)
1 /*    regexec.c
2  */
3 
4 /*
5  *	One Ring to rule them all, One Ring to find them
6  *
7  *     [p.v of _The Lord of the Rings_, opening poem]
8  *     [p.50 of _The Lord of the Rings_, I/iii: "The Shadow of the Past"]
9  *     [p.254 of _The Lord of the Rings_, II/ii: "The Council of Elrond"]
10  */
11 
12 /* This file contains functions for executing a regular expression.  See
13  * also regcomp.c which funnily enough, contains functions for compiling
14  * a regular expression.
15  *
16  * This file is also copied at build time to ext/re/re_exec.c, where
17  * it's built with -DPERL_EXT_RE_BUILD -DPERL_EXT_RE_DEBUG -DPERL_EXT.
18  * This causes the main functions to be compiled under new names and with
19  * debugging support added, which makes "use re 'debug'" work.
20  */
21 
22 /* NOTE: this is derived from Henry Spencer's regexp code, and should not
23  * confused with the original package (see point 3 below).  Thanks, Henry!
24  */
25 
26 /* Additional note: this code is very heavily munged from Henry's version
27  * in places.  In some spots I've traded clarity for efficiency, so don't
28  * blame Henry for some of the lack of readability.
29  */
30 
31 /* The names of the functions have been changed from regcomp and
32  * regexec to  pregcomp and pregexec in order to avoid conflicts
33  * with the POSIX routines of the same names.
34 */
35 
36 #ifdef PERL_EXT_RE_BUILD
37 #include "re_top.h"
38 #endif
39 
40 /*
41  * pregcomp and pregexec -- regsub and regerror are not used in perl
42  *
43  *	Copyright (c) 1986 by University of Toronto.
44  *	Written by Henry Spencer.  Not derived from licensed software.
45  *
46  *	Permission is granted to anyone to use this software for any
47  *	purpose on any computer system, and to redistribute it freely,
48  *	subject to the following restrictions:
49  *
50  *	1. The author is not responsible for the consequences of use of
51  *		this software, no matter how awful, even if they arise
52  *		from defects in it.
53  *
54  *	2. The origin of this software must not be misrepresented, either
55  *		by explicit claim or by omission.
56  *
57  *	3. Altered versions must be plainly marked as such, and must not
58  *		be misrepresented as being the original software.
59  *
60  ****    Alterations to Henry's code are...
61  ****
62  ****    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
63  ****    2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
64  ****    by Larry Wall and others
65  ****
66  ****    You may distribute under the terms of either the GNU General Public
67  ****    License or the Artistic License, as specified in the README file.
68  *
69  * Beware that some of this code is subtly aware of the way operator
70  * precedence is structured in regular expressions.  Serious changes in
71  * regular-expression syntax might require a total rethink.
72  */
73 #include "EXTERN.h"
74 #define PERL_IN_REGEXEC_C
75 #include "perl.h"
76 
77 #ifdef PERL_IN_XSUB_RE
78 #  include "re_comp.h"
79 #else
80 #  include "regcomp.h"
81 #endif
82 
83 #include "invlist_inline.h"
84 #include "unicode_constants.h"
85 
86 #define B_ON_NON_UTF8_LOCALE_IS_WRONG            \
87  "Use of \\b{} or \\B{} for non-UTF-8 locale is wrong.  Assuming a UTF-8 locale"
88 
89 static const char utf8_locale_required[] =
90       "Use of (?[ ]) for non-UTF-8 locale is wrong.  Assuming a UTF-8 locale";
91 
92 #ifdef DEBUGGING
93 /* At least one required character in the target string is expressible only in
94  * UTF-8. */
95 static const char* const non_utf8_target_but_utf8_required
96                 = "Can't match, because target string needs to be in UTF-8\n";
97 #endif
98 
99 /* Returns a boolean as to whether the input unsigned number is a power of 2
100  * (2**0, 2**1, etc).  In other words if it has just a single bit set.
101  * If not, subtracting 1 would leave the uppermost bit set, so the & would
102  * yield non-zero */
103 #define isPOWER_OF_2(n) ((n & (n-1)) == 0)
104 
105 #define NON_UTF8_TARGET_BUT_UTF8_REQUIRED(target) STMT_START {           \
106     DEBUG_EXECUTE_r(Perl_re_printf( aTHX_  "%s", non_utf8_target_but_utf8_required));\
107     goto target;                                                         \
108 } STMT_END
109 
110 #define HAS_NONLATIN1_FOLD_CLOSURE(i) _HAS_NONLATIN1_FOLD_CLOSURE_ONLY_FOR_USE_BY_REGCOMP_DOT_C_AND_REGEXEC_DOT_C(i)
111 
112 #ifndef STATIC
113 #define	STATIC	static
114 #endif
115 
116 /* Valid only if 'c', the character being looke-up, is an invariant under
117  * UTF-8: it avoids the reginclass call if there are no complications: i.e., if
118  * everything matchable is straight forward in the bitmap */
119 #define REGINCLASS(prog,p,c,u)  (ANYOF_FLAGS(p)                             \
120                                 ? reginclass(prog,p,c,c+1,u)                \
121                                 : ANYOF_BITMAP_TEST(p,*(c)))
122 
123 /*
124  * Forwards.
125  */
126 
127 #define CHR_SVLEN(sv) (utf8_target ? sv_len_utf8(sv) : SvCUR(sv))
128 
129 #define HOPc(pos,off) \
130 	(char *)(reginfo->is_utf8_target \
131 	    ? reghop3((U8*)pos, off, \
132                     (U8*)(off >= 0 ? reginfo->strend : reginfo->strbeg)) \
133 	    : (U8*)(pos + off))
134 
135 /* like HOPMAYBE3 but backwards. lim must be +ve. Returns NULL on overshoot */
136 #define HOPBACK3(pos, off, lim) \
137 	(reginfo->is_utf8_target                          \
138 	    ? reghopmaybe3((U8*)pos, (SSize_t)0-off, (U8*)(lim)) \
139 	    : (pos - off >= lim)	                         \
140 		? (U8*)pos - off		                 \
141 		: NULL)
142 
143 #define HOPBACKc(pos, off) ((char*)HOPBACK3(pos, off, reginfo->strbeg))
144 
145 #define HOP3(pos,off,lim) (reginfo->is_utf8_target  ? reghop3((U8*)(pos), off, (U8*)(lim)) : (U8*)(pos + off))
146 #define HOP3c(pos,off,lim) ((char*)HOP3(pos,off,lim))
147 
148 /* lim must be +ve. Returns NULL on overshoot */
149 #define HOPMAYBE3(pos,off,lim) \
150 	(reginfo->is_utf8_target                        \
151 	    ? reghopmaybe3((U8*)pos, off, (U8*)(lim))   \
152 	    : ((U8*)pos + off <= lim)                   \
153 		? (U8*)pos + off                        \
154 		: NULL)
155 
156 /* like HOP3, but limits the result to <= lim even for the non-utf8 case.
157  * off must be >=0; args should be vars rather than expressions */
158 #define HOP3lim(pos,off,lim) (reginfo->is_utf8_target \
159     ? reghop3((U8*)(pos), off, (U8*)(lim)) \
160     : (U8*)((pos + off) > lim ? lim : (pos + off)))
161 #define HOP3clim(pos,off,lim) ((char*)HOP3lim(pos,off,lim))
162 
163 #define HOP4(pos,off,llim, rlim) (reginfo->is_utf8_target \
164     ? reghop4((U8*)(pos), off, (U8*)(llim), (U8*)(rlim)) \
165     : (U8*)(pos + off))
166 #define HOP4c(pos,off,llim, rlim) ((char*)HOP4(pos,off,llim, rlim))
167 
168 #define NEXTCHR_EOS -10 /* nextchr has fallen off the end */
169 #define NEXTCHR_IS_EOS (nextchr < 0)
170 
171 #define SET_nextchr \
172     nextchr = ((locinput < reginfo->strend) ? UCHARAT(locinput) : NEXTCHR_EOS)
173 
174 #define SET_locinput(p) \
175     locinput = (p);  \
176     SET_nextchr
177 
178 #define PLACEHOLDER	/* Something for the preprocessor to grab onto */
179 /* TODO: Combine JUMPABLE and HAS_TEXT to cache OP(rn) */
180 
181 /* for use after a quantifier and before an EXACT-like node -- japhy */
182 /* it would be nice to rework regcomp.sym to generate this stuff. sigh
183  *
184  * NOTE that *nothing* that affects backtracking should be in here, specifically
185  * VERBS must NOT be included. JUMPABLE is used to determine  if we can ignore a
186  * node that is in between two EXACT like nodes when ascertaining what the required
187  * "follow" character is. This should probably be moved to regex compile time
188  * although it may be done at run time beause of the REF possibility - more
189  * investigation required. -- demerphq
190 */
191 #define JUMPABLE(rn) (                                                             \
192     OP(rn) == OPEN ||                                                              \
193     (OP(rn) == CLOSE &&                                                            \
194      !EVAL_CLOSE_PAREN_IS(cur_eval,ARG(rn)) ) ||                                   \
195     OP(rn) == EVAL ||                                                              \
196     OP(rn) == SUSPEND || OP(rn) == IFMATCH ||                                      \
197     OP(rn) == PLUS || OP(rn) == MINMOD ||                                          \
198     OP(rn) == KEEPS ||                                                             \
199     (PL_regkind[OP(rn)] == CURLY && ARG1(rn) > 0)                                  \
200 )
201 #define IS_EXACT(rn) (PL_regkind[OP(rn)] == EXACT)
202 
203 #define HAS_TEXT(rn) ( IS_EXACT(rn) || PL_regkind[OP(rn)] == REF )
204 
205 #if 0
206 /* Currently these are only used when PL_regkind[OP(rn)] == EXACT so
207    we don't need this definition.  XXX These are now out-of-sync*/
208 #define IS_TEXT(rn)   ( OP(rn)==EXACT   || OP(rn)==REF   || OP(rn)==NREF   )
209 #define IS_TEXTF(rn)  ( OP(rn)==EXACTFU || OP(rn)==EXACTFU_SS || OP(rn)==EXACTFAA || OP(rn)==EXACTFAA_NO_TRIE || OP(rn)==EXACTF || OP(rn)==REFF  || OP(rn)==NREFF )
210 #define IS_TEXTFL(rn) ( OP(rn)==EXACTFL || OP(rn)==REFFL || OP(rn)==NREFFL )
211 
212 #else
213 /* ... so we use this as its faster. */
214 #define IS_TEXT(rn)   ( OP(rn)==EXACT || OP(rn)==EXACTL )
215 #define IS_TEXTFU(rn)  ( OP(rn)==EXACTFU || OP(rn)==EXACTFLU8 || OP(rn)==EXACTFU_SS || OP(rn) == EXACTFAA || OP(rn) == EXACTFAA_NO_TRIE)
216 #define IS_TEXTF(rn)  ( OP(rn)==EXACTF  )
217 #define IS_TEXTFL(rn) ( OP(rn)==EXACTFL )
218 
219 #endif
220 
221 /*
222   Search for mandatory following text node; for lookahead, the text must
223   follow but for lookbehind (rn->flags != 0) we skip to the next step.
224 */
225 #define FIND_NEXT_IMPT(rn) STMT_START {                                   \
226     while (JUMPABLE(rn)) { \
227 	const OPCODE type = OP(rn); \
228 	if (type == SUSPEND || PL_regkind[type] == CURLY) \
229 	    rn = NEXTOPER(NEXTOPER(rn)); \
230 	else if (type == PLUS) \
231 	    rn = NEXTOPER(rn); \
232 	else if (type == IFMATCH) \
233 	    rn = (rn->flags == 0) ? NEXTOPER(NEXTOPER(rn)) : rn + ARG(rn); \
234 	else rn += NEXT_OFF(rn); \
235     } \
236 } STMT_END
237 
238 #define SLAB_FIRST(s) (&(s)->states[0])
239 #define SLAB_LAST(s)  (&(s)->states[PERL_REGMATCH_SLAB_SLOTS-1])
240 
241 static void S_setup_eval_state(pTHX_ regmatch_info *const reginfo);
242 static void S_cleanup_regmatch_info_aux(pTHX_ void *arg);
243 static regmatch_state * S_push_slab(pTHX);
244 
245 #define REGCP_PAREN_ELEMS 3
246 #define REGCP_OTHER_ELEMS 3
247 #define REGCP_FRAME_ELEMS 1
248 /* REGCP_FRAME_ELEMS are not part of the REGCP_OTHER_ELEMS and
249  * are needed for the regexp context stack bookkeeping. */
250 
251 STATIC CHECKPOINT
252 S_regcppush(pTHX_ const regexp *rex, I32 parenfloor, U32 maxopenparen _pDEPTH)
253 {
254     const int retval = PL_savestack_ix;
255     const int paren_elems_to_push =
256                 (maxopenparen - parenfloor) * REGCP_PAREN_ELEMS;
257     const UV total_elems = paren_elems_to_push + REGCP_OTHER_ELEMS;
258     const UV elems_shifted = total_elems << SAVE_TIGHT_SHIFT;
259     I32 p;
260     GET_RE_DEBUG_FLAGS_DECL;
261 
262     PERL_ARGS_ASSERT_REGCPPUSH;
263 
264     if (paren_elems_to_push < 0)
265         Perl_croak(aTHX_ "panic: paren_elems_to_push, %i < 0, maxopenparen: %i parenfloor: %i REGCP_PAREN_ELEMS: %u",
266                    (int)paren_elems_to_push, (int)maxopenparen,
267                    (int)parenfloor, (unsigned)REGCP_PAREN_ELEMS);
268 
269     if ((elems_shifted >> SAVE_TIGHT_SHIFT) != total_elems)
270 	Perl_croak(aTHX_ "panic: paren_elems_to_push offset %" UVuf
271 		   " out of range (%lu-%ld)",
272 		   total_elems,
273                    (unsigned long)maxopenparen,
274                    (long)parenfloor);
275 
276     SSGROW(total_elems + REGCP_FRAME_ELEMS);
277 
278     DEBUG_BUFFERS_r(
279 	if ((int)maxopenparen > (int)parenfloor)
280             Perl_re_exec_indentf( aTHX_
281 		"rex=0x%" UVxf " offs=0x%" UVxf ": saving capture indices:\n",
282 		depth,
283                 PTR2UV(rex),
284 		PTR2UV(rex->offs)
285 	    );
286     );
287     for (p = parenfloor+1; p <= (I32)maxopenparen;  p++) {
288 /* REGCP_PARENS_ELEMS are pushed per pairs of parentheses. */
289 	SSPUSHIV(rex->offs[p].end);
290 	SSPUSHIV(rex->offs[p].start);
291 	SSPUSHINT(rex->offs[p].start_tmp);
292         DEBUG_BUFFERS_r(Perl_re_exec_indentf( aTHX_
293 	    "    \\%" UVuf ": %" IVdf "(%" IVdf ")..%" IVdf "\n",
294 	    depth,
295             (UV)p,
296 	    (IV)rex->offs[p].start,
297 	    (IV)rex->offs[p].start_tmp,
298 	    (IV)rex->offs[p].end
299 	));
300     }
301 /* REGCP_OTHER_ELEMS are pushed in any case, parentheses or no. */
302     SSPUSHINT(maxopenparen);
303     SSPUSHINT(rex->lastparen);
304     SSPUSHINT(rex->lastcloseparen);
305     SSPUSHUV(SAVEt_REGCONTEXT | elems_shifted); /* Magic cookie. */
306 
307     return retval;
308 }
309 
310 /* These are needed since we do not localize EVAL nodes: */
311 #define REGCP_SET(cp)                                           \
312     DEBUG_STATE_r(                                              \
313         Perl_re_exec_indentf( aTHX_                             \
314             "Setting an EVAL scope, savestack=%" IVdf ",\n",    \
315             depth, (IV)PL_savestack_ix                          \
316         )                                                       \
317     );                                                          \
318     cp = PL_savestack_ix
319 
320 #define REGCP_UNWIND(cp)                                        \
321     DEBUG_STATE_r(                                              \
322         if (cp != PL_savestack_ix)                              \
323             Perl_re_exec_indentf( aTHX_                         \
324                 "Clearing an EVAL scope, savestack=%"           \
325                 IVdf "..%" IVdf "\n",                           \
326                 depth, (IV)(cp), (IV)PL_savestack_ix            \
327             )                                                   \
328     );                                                          \
329     regcpblow(cp)
330 
331 #define UNWIND_PAREN(lp, lcp)               \
332     for (n = rex->lastparen; n > lp; n--)   \
333         rex->offs[n].end = -1;              \
334     rex->lastparen = n;                     \
335     rex->lastcloseparen = lcp;
336 
337 
338 STATIC void
339 S_regcppop(pTHX_ regexp *rex, U32 *maxopenparen_p _pDEPTH)
340 {
341     UV i;
342     U32 paren;
343     GET_RE_DEBUG_FLAGS_DECL;
344 
345     PERL_ARGS_ASSERT_REGCPPOP;
346 
347     /* Pop REGCP_OTHER_ELEMS before the parentheses loop starts. */
348     i = SSPOPUV;
349     assert((i & SAVE_MASK) == SAVEt_REGCONTEXT); /* Check that the magic cookie is there. */
350     i >>= SAVE_TIGHT_SHIFT; /* Parentheses elements to pop. */
351     rex->lastcloseparen = SSPOPINT;
352     rex->lastparen = SSPOPINT;
353     *maxopenparen_p = SSPOPINT;
354 
355     i -= REGCP_OTHER_ELEMS;
356     /* Now restore the parentheses context. */
357     DEBUG_BUFFERS_r(
358 	if (i || rex->lastparen + 1 <= rex->nparens)
359             Perl_re_exec_indentf( aTHX_
360 		"rex=0x%" UVxf " offs=0x%" UVxf ": restoring capture indices to:\n",
361 		depth,
362                 PTR2UV(rex),
363 		PTR2UV(rex->offs)
364 	    );
365     );
366     paren = *maxopenparen_p;
367     for ( ; i > 0; i -= REGCP_PAREN_ELEMS) {
368 	SSize_t tmps;
369 	rex->offs[paren].start_tmp = SSPOPINT;
370 	rex->offs[paren].start = SSPOPIV;
371 	tmps = SSPOPIV;
372 	if (paren <= rex->lastparen)
373 	    rex->offs[paren].end = tmps;
374         DEBUG_BUFFERS_r( Perl_re_exec_indentf( aTHX_
375 	    "    \\%" UVuf ": %" IVdf "(%" IVdf ")..%" IVdf "%s\n",
376 	    depth,
377             (UV)paren,
378 	    (IV)rex->offs[paren].start,
379 	    (IV)rex->offs[paren].start_tmp,
380 	    (IV)rex->offs[paren].end,
381 	    (paren > rex->lastparen ? "(skipped)" : ""));
382 	);
383 	paren--;
384     }
385 #if 1
386     /* It would seem that the similar code in regtry()
387      * already takes care of this, and in fact it is in
388      * a better location to since this code can #if 0-ed out
389      * but the code in regtry() is needed or otherwise tests
390      * requiring null fields (pat.t#187 and split.t#{13,14}
391      * (as of patchlevel 7877)  will fail.  Then again,
392      * this code seems to be necessary or otherwise
393      * this erroneously leaves $1 defined: "1" =~ /^(?:(\d)x)?\d$/
394      * --jhi updated by dapm */
395     for (i = rex->lastparen + 1; i <= rex->nparens; i++) {
396 	if (i > *maxopenparen_p)
397 	    rex->offs[i].start = -1;
398 	rex->offs[i].end = -1;
399         DEBUG_BUFFERS_r( Perl_re_exec_indentf( aTHX_
400 	    "    \\%" UVuf ": %s   ..-1 undeffing\n",
401 	    depth,
402             (UV)i,
403 	    (i > *maxopenparen_p) ? "-1" : "  "
404 	));
405     }
406 #endif
407 }
408 
409 /* restore the parens and associated vars at savestack position ix,
410  * but without popping the stack */
411 
412 STATIC void
413 S_regcp_restore(pTHX_ regexp *rex, I32 ix, U32 *maxopenparen_p _pDEPTH)
414 {
415     I32 tmpix = PL_savestack_ix;
416     PERL_ARGS_ASSERT_REGCP_RESTORE;
417 
418     PL_savestack_ix = ix;
419     regcppop(rex, maxopenparen_p);
420     PL_savestack_ix = tmpix;
421 }
422 
423 #define regcpblow(cp) LEAVE_SCOPE(cp)	/* Ignores regcppush()ed data. */
424 
425 #ifndef PERL_IN_XSUB_RE
426 
427 bool
428 Perl_isFOO_lc(pTHX_ const U8 classnum, const U8 character)
429 {
430     /* Returns a boolean as to whether or not 'character' is a member of the
431      * Posix character class given by 'classnum' that should be equivalent to a
432      * value in the typedef '_char_class_number'.
433      *
434      * Ideally this could be replaced by a just an array of function pointers
435      * to the C library functions that implement the macros this calls.
436      * However, to compile, the precise function signatures are required, and
437      * these may vary from platform to to platform.  To avoid having to figure
438      * out what those all are on each platform, I (khw) am using this method,
439      * which adds an extra layer of function call overhead (unless the C
440      * optimizer strips it away).  But we don't particularly care about
441      * performance with locales anyway. */
442 
443     switch ((_char_class_number) classnum) {
444         case _CC_ENUM_ALPHANUMERIC: return isALPHANUMERIC_LC(character);
445         case _CC_ENUM_ALPHA:     return isALPHA_LC(character);
446         case _CC_ENUM_ASCII:     return isASCII_LC(character);
447         case _CC_ENUM_BLANK:     return isBLANK_LC(character);
448         case _CC_ENUM_CASED:     return    isLOWER_LC(character)
449                                         || isUPPER_LC(character);
450         case _CC_ENUM_CNTRL:     return isCNTRL_LC(character);
451         case _CC_ENUM_DIGIT:     return isDIGIT_LC(character);
452         case _CC_ENUM_GRAPH:     return isGRAPH_LC(character);
453         case _CC_ENUM_LOWER:     return isLOWER_LC(character);
454         case _CC_ENUM_PRINT:     return isPRINT_LC(character);
455         case _CC_ENUM_PUNCT:     return isPUNCT_LC(character);
456         case _CC_ENUM_SPACE:     return isSPACE_LC(character);
457         case _CC_ENUM_UPPER:     return isUPPER_LC(character);
458         case _CC_ENUM_WORDCHAR:  return isWORDCHAR_LC(character);
459         case _CC_ENUM_XDIGIT:    return isXDIGIT_LC(character);
460         default:    /* VERTSPACE should never occur in locales */
461             Perl_croak(aTHX_ "panic: isFOO_lc() has an unexpected character class '%d'", classnum);
462     }
463 
464     NOT_REACHED; /* NOTREACHED */
465     return FALSE;
466 }
467 
468 #endif
469 
470 STATIC bool
471 S_isFOO_utf8_lc(pTHX_ const U8 classnum, const U8* character, const U8* e)
472 {
473     /* Returns a boolean as to whether or not the (well-formed) UTF-8-encoded
474      * 'character' is a member of the Posix character class given by 'classnum'
475      * that should be equivalent to a value in the typedef
476      * '_char_class_number'.
477      *
478      * This just calls isFOO_lc on the code point for the character if it is in
479      * the range 0-255.  Outside that range, all characters use Unicode
480      * rules, ignoring any locale.  So use the Unicode function if this class
481      * requires a swash, and use the Unicode macro otherwise. */
482 
483     PERL_ARGS_ASSERT_ISFOO_UTF8_LC;
484 
485     if (UTF8_IS_INVARIANT(*character)) {
486         return isFOO_lc(classnum, *character);
487     }
488     else if (UTF8_IS_DOWNGRADEABLE_START(*character)) {
489         return isFOO_lc(classnum,
490                         EIGHT_BIT_UTF8_TO_NATIVE(*character, *(character + 1)));
491     }
492 
493     _CHECK_AND_OUTPUT_WIDE_LOCALE_UTF8_MSG(character, e);
494 
495     switch ((_char_class_number) classnum) {
496         case _CC_ENUM_SPACE:     return is_XPERLSPACE_high(character);
497         case _CC_ENUM_BLANK:     return is_HORIZWS_high(character);
498         case _CC_ENUM_XDIGIT:    return is_XDIGIT_high(character);
499         case _CC_ENUM_VERTSPACE: return is_VERTWS_high(character);
500         default:
501             return _invlist_contains_cp(PL_XPosix_ptrs[classnum],
502                                         utf8_to_uvchr_buf(character, e, NULL));
503     }
504 
505     return FALSE; /* Things like CNTRL are always below 256 */
506 }
507 
508 STATIC char *
509 S_find_next_ascii(char * s, const char * send, const bool utf8_target)
510 {
511     /* Returns the position of the first ASCII byte in the sequence between 's'
512      * and 'send-1' inclusive; returns 'send' if none found */
513 
514     PERL_ARGS_ASSERT_FIND_NEXT_ASCII;
515 
516 #ifndef EBCDIC
517 
518     if ((STRLEN) (send - s) >= PERL_WORDSIZE
519 
520                             /* This term is wordsize if subword; 0 if not */
521                           + PERL_WORDSIZE * PERL_IS_SUBWORD_ADDR(s)
522 
523                             /* 'offset' */
524                           - (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK))
525     {
526 
527         /* Process per-byte until reach word boundary.  XXX This loop could be
528          * eliminated if we knew that this platform had fast unaligned reads */
529         while (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK) {
530             if (isASCII(*s)) {
531                 return s;
532             }
533             s++;    /* khw didn't bother creating a separate loop for
534                        utf8_target */
535         }
536 
537         /* Here, we know we have at least one full word to process.  Process
538          * per-word as long as we have at least a full word left */
539         do {
540             PERL_UINTMAX_T complemented = ~ * (PERL_UINTMAX_T *) s;
541             if (complemented & PERL_VARIANTS_WORD_MASK)  {
542 
543 #  if   BYTEORDER == 0x1234 || BYTEORDER == 0x12345678    \
544      || BYTEORDER == 0x4321 || BYTEORDER == 0x87654321
545 
546                 s += _variant_byte_number(complemented);
547                 return s;
548 
549 #  else   /* If weird byte order, drop into next loop to do byte-at-a-time
550            checks. */
551 
552                 break;
553 #  endif
554             }
555 
556             s += PERL_WORDSIZE;
557 
558         } while (s + PERL_WORDSIZE <= send);
559     }
560 
561 #endif
562 
563     /* Process per-character */
564     if (utf8_target) {
565         while (s < send) {
566             if (isASCII(*s)) {
567                 return s;
568             }
569             s += UTF8SKIP(s);
570         }
571     }
572     else {
573         while (s < send) {
574             if (isASCII(*s)) {
575                 return s;
576             }
577             s++;
578         }
579     }
580 
581     return s;
582 }
583 
584 STATIC char *
585 S_find_next_non_ascii(char * s, const char * send, const bool utf8_target)
586 {
587     /* Returns the position of the first non-ASCII byte in the sequence between
588      * 's' and 'send-1' inclusive; returns 'send' if none found */
589 
590 #ifdef EBCDIC
591 
592     PERL_ARGS_ASSERT_FIND_NEXT_NON_ASCII;
593 
594     if (utf8_target) {
595         while (s < send) {
596             if ( ! isASCII(*s)) {
597                 return s;
598             }
599             s += UTF8SKIP(s);
600         }
601     }
602     else {
603         while (s < send) {
604             if ( ! isASCII(*s)) {
605                 return s;
606             }
607             s++;
608         }
609     }
610 
611     return s;
612 
613 #else
614 
615     const U8 * next_non_ascii = NULL;
616 
617     PERL_ARGS_ASSERT_FIND_NEXT_NON_ASCII;
618     PERL_UNUSED_ARG(utf8_target);
619 
620     /* On ASCII platforms invariants and ASCII are identical, so if the string
621      * is entirely invariants, there is no non-ASCII character */
622     return (is_utf8_invariant_string_loc((U8 *) s,
623                                          (STRLEN) (send - s),
624                                          &next_non_ascii))
625             ? (char *) send
626             : (char *) next_non_ascii;
627 
628 #endif
629 
630 }
631 
632 STATIC U8 *
633 S_find_span_end(U8 * s, const U8 * send, const U8 span_byte)
634 {
635     /* Returns the position of the first byte in the sequence between 's' and
636      * 'send-1' inclusive that isn't 'span_byte'; returns 'send' if none found.
637      * */
638 
639     PERL_ARGS_ASSERT_FIND_SPAN_END;
640 
641     assert(send >= s);
642 
643     if ((STRLEN) (send - s) >= PERL_WORDSIZE
644                           + PERL_WORDSIZE * PERL_IS_SUBWORD_ADDR(s)
645                           - (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK))
646     {
647         PERL_UINTMAX_T span_word;
648 
649         /* Process per-byte until reach word boundary.  XXX This loop could be
650          * eliminated if we knew that this platform had fast unaligned reads */
651         while (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK) {
652             if (*s != span_byte) {
653                 return s;
654             }
655             s++;
656         }
657 
658         /* Create a word filled with the bytes we are spanning */
659         span_word = PERL_COUNT_MULTIPLIER * span_byte;
660 
661         /* Process per-word as long as we have at least a full word left */
662         do {
663 
664             /* Keep going if the whole word is composed of 'span_byte's */
665             if ((* (PERL_UINTMAX_T *) s) == span_word)  {
666                 s += PERL_WORDSIZE;
667                 continue;
668             }
669 
670             /* Here, at least one byte in the word isn't 'span_byte'. */
671 
672 #ifdef EBCDIC
673 
674             break;
675 
676 #else
677 
678             /* This xor leaves 1 bits only in those non-matching bytes */
679             span_word ^= * (PERL_UINTMAX_T *) s;
680 
681             /* Make sure the upper bit of each non-matching byte is set.  This
682              * makes each such byte look like an ASCII platform variant byte */
683             span_word |= span_word << 1;
684             span_word |= span_word << 2;
685             span_word |= span_word << 4;
686 
687             /* That reduces the problem to what this function solves */
688             return s + _variant_byte_number(span_word);
689 
690 #endif
691 
692         } while (s + PERL_WORDSIZE <= send);
693     }
694 
695     /* Process the straggler bytes beyond the final word boundary */
696     while (s < send) {
697         if (*s != span_byte) {
698             return s;
699         }
700         s++;
701     }
702 
703     return s;
704 }
705 
706 STATIC U8 *
707 S_find_next_masked(U8 * s, const U8 * send, const U8 byte, const U8 mask)
708 {
709     /* Returns the position of the first byte in the sequence between 's'
710      * and 'send-1' inclusive that when ANDed with 'mask' yields 'byte';
711      * returns 'send' if none found.  It uses word-level operations instead of
712      * byte to speed up the process */
713 
714     PERL_ARGS_ASSERT_FIND_NEXT_MASKED;
715 
716     assert(send >= s);
717     assert((byte & mask) == byte);
718 
719 #ifndef EBCDIC
720 
721     if ((STRLEN) (send - s) >= PERL_WORDSIZE
722                           + PERL_WORDSIZE * PERL_IS_SUBWORD_ADDR(s)
723                           - (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK))
724     {
725         PERL_UINTMAX_T word_complemented, mask_word;
726 
727         while (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK) {
728             if (((*s) & mask) == byte) {
729                 return s;
730             }
731             s++;
732         }
733 
734         word_complemented = ~ (PERL_COUNT_MULTIPLIER * byte);
735         mask_word =            PERL_COUNT_MULTIPLIER * mask;
736 
737         do {
738             PERL_UINTMAX_T masked = (* (PERL_UINTMAX_T *) s) & mask_word;
739 
740             /* If 'masked' contains 'byte' within it, anding with the
741              * complement will leave those 8 bits 0 */
742             masked &= word_complemented;
743 
744             /* This causes the most significant bit to be set to 1 for any
745              * bytes in the word that aren't completely 0 */
746             masked |= masked << 1;
747             masked |= masked << 2;
748             masked |= masked << 4;
749 
750             /* The msbits are the same as what marks a byte as variant, so we
751              * can use this mask.  If all msbits are 1, the word doesn't
752              * contain 'byte' */
753             if ((masked & PERL_VARIANTS_WORD_MASK) == PERL_VARIANTS_WORD_MASK) {
754                 s += PERL_WORDSIZE;
755                 continue;
756             }
757 
758             /* Here, the msbit of bytes in the word that aren't 'byte' are 1,
759              * and any that are, are 0.  Complement and re-AND to swap that */
760             masked = ~ masked;
761             masked &= PERL_VARIANTS_WORD_MASK;
762 
763             /* This reduces the problem to that solved by this function */
764             s += _variant_byte_number(masked);
765             return s;
766 
767         } while (s + PERL_WORDSIZE <= send);
768     }
769 
770 #endif
771 
772     while (s < send) {
773         if (((*s) & mask) == byte) {
774             return s;
775         }
776         s++;
777     }
778 
779     return s;
780 }
781 
782 STATIC U8 *
783 S_find_span_end_mask(U8 * s, const U8 * send, const U8 span_byte, const U8 mask)
784 {
785     /* Returns the position of the first byte in the sequence between 's' and
786      * 'send-1' inclusive that when ANDed with 'mask' isn't 'span_byte'.
787      * 'span_byte' should have been ANDed with 'mask' in the call of this
788      * function.  Returns 'send' if none found.  Works like find_span_end(),
789      * except for the AND */
790 
791     PERL_ARGS_ASSERT_FIND_SPAN_END_MASK;
792 
793     assert(send >= s);
794     assert((span_byte & mask) == span_byte);
795 
796     if ((STRLEN) (send - s) >= PERL_WORDSIZE
797                           + PERL_WORDSIZE * PERL_IS_SUBWORD_ADDR(s)
798                           - (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK))
799     {
800         PERL_UINTMAX_T span_word, mask_word;
801 
802         while (PTR2nat(s) & PERL_WORD_BOUNDARY_MASK) {
803             if (((*s) & mask) != span_byte) {
804                 return s;
805             }
806             s++;
807         }
808 
809         span_word = PERL_COUNT_MULTIPLIER * span_byte;
810         mask_word = PERL_COUNT_MULTIPLIER * mask;
811 
812         do {
813             PERL_UINTMAX_T masked = (* (PERL_UINTMAX_T *) s) & mask_word;
814 
815             if (masked == span_word) {
816                 s += PERL_WORDSIZE;
817                 continue;
818             }
819 
820 #ifdef EBCDIC
821 
822             break;
823 
824 #else
825 
826             masked ^= span_word;
827             masked |= masked << 1;
828             masked |= masked << 2;
829             masked |= masked << 4;
830             return s + _variant_byte_number(masked);
831 
832 #endif
833 
834         } while (s + PERL_WORDSIZE <= send);
835     }
836 
837     while (s < send) {
838         if (((*s) & mask) != span_byte) {
839             return s;
840         }
841         s++;
842     }
843 
844     return s;
845 }
846 
847 /*
848  * pregexec and friends
849  */
850 
851 #ifndef PERL_IN_XSUB_RE
852 /*
853  - pregexec - match a regexp against a string
854  */
855 I32
856 Perl_pregexec(pTHX_ REGEXP * const prog, char* stringarg, char *strend,
857 	 char *strbeg, SSize_t minend, SV *screamer, U32 nosave)
858 /* stringarg: the point in the string at which to begin matching */
859 /* strend:    pointer to null at end of string */
860 /* strbeg:    real beginning of string */
861 /* minend:    end of match must be >= minend bytes after stringarg. */
862 /* screamer:  SV being matched: only used for utf8 flag, pos() etc; string
863  *            itself is accessed via the pointers above */
864 /* nosave:    For optimizations. */
865 {
866     PERL_ARGS_ASSERT_PREGEXEC;
867 
868     return
869 	regexec_flags(prog, stringarg, strend, strbeg, minend, screamer, NULL,
870 		      nosave ? 0 : REXEC_COPY_STR);
871 }
872 #endif
873 
874 
875 
876 /* re_intuit_start():
877  *
878  * Based on some optimiser hints, try to find the earliest position in the
879  * string where the regex could match.
880  *
881  *   rx:     the regex to match against
882  *   sv:     the SV being matched: only used for utf8 flag; the string
883  *           itself is accessed via the pointers below. Note that on
884  *           something like an overloaded SV, SvPOK(sv) may be false
885  *           and the string pointers may point to something unrelated to
886  *           the SV itself.
887  *   strbeg: real beginning of string
888  *   strpos: the point in the string at which to begin matching
889  *   strend: pointer to the byte following the last char of the string
890  *   flags   currently unused; set to 0
891  *   data:   currently unused; set to NULL
892  *
893  * The basic idea of re_intuit_start() is to use some known information
894  * about the pattern, namely:
895  *
896  *   a) the longest known anchored substring (i.e. one that's at a
897  *      constant offset from the beginning of the pattern; but not
898  *      necessarily at a fixed offset from the beginning of the
899  *      string);
900  *   b) the longest floating substring (i.e. one that's not at a constant
901  *      offset from the beginning of the pattern);
902  *   c) Whether the pattern is anchored to the string; either
903  *      an absolute anchor: /^../, or anchored to \n: /^.../m,
904  *      or anchored to pos(): /\G/;
905  *   d) A start class: a real or synthetic character class which
906  *      represents which characters are legal at the start of the pattern;
907  *
908  * to either quickly reject the match, or to find the earliest position
909  * within the string at which the pattern might match, thus avoiding
910  * running the full NFA engine at those earlier locations, only to
911  * eventually fail and retry further along.
912  *
913  * Returns NULL if the pattern can't match, or returns the address within
914  * the string which is the earliest place the match could occur.
915  *
916  * The longest of the anchored and floating substrings is called 'check'
917  * and is checked first. The other is called 'other' and is checked
918  * second. The 'other' substring may not be present.  For example,
919  *
920  *    /(abc|xyz)ABC\d{0,3}DEFG/
921  *
922  * will have
923  *
924  *   check substr (float)    = "DEFG", offset 6..9 chars
925  *   other substr (anchored) = "ABC",  offset 3..3 chars
926  *   stclass = [ax]
927  *
928  * Be aware that during the course of this function, sometimes 'anchored'
929  * refers to a substring being anchored relative to the start of the
930  * pattern, and sometimes to the pattern itself being anchored relative to
931  * the string. For example:
932  *
933  *   /\dabc/:   "abc" is anchored to the pattern;
934  *   /^\dabc/:  "abc" is anchored to the pattern and the string;
935  *   /\d+abc/:  "abc" is anchored to neither the pattern nor the string;
936  *   /^\d+abc/: "abc" is anchored to neither the pattern nor the string,
937  *                    but the pattern is anchored to the string.
938  */
939 
940 char *
941 Perl_re_intuit_start(pTHX_
942                     REGEXP * const rx,
943                     SV *sv,
944                     const char * const strbeg,
945                     char *strpos,
946                     char *strend,
947                     const U32 flags,
948                     re_scream_pos_data *data)
949 {
950     struct regexp *const prog = ReANY(rx);
951     SSize_t start_shift = prog->check_offset_min;
952     /* Should be nonnegative! */
953     SSize_t end_shift   = 0;
954     /* current lowest pos in string where the regex can start matching */
955     char *rx_origin = strpos;
956     SV *check;
957     const bool utf8_target = (sv && SvUTF8(sv)) ? 1 : 0; /* if no sv we have to assume bytes */
958     U8   other_ix = 1 - prog->substrs->check_ix;
959     bool ml_anch = 0;
960     char *other_last = strpos;/* latest pos 'other' substr already checked to */
961     char *check_at = NULL;		/* check substr found at this pos */
962     const I32 multiline = prog->extflags & RXf_PMf_MULTILINE;
963     RXi_GET_DECL(prog,progi);
964     regmatch_info reginfo_buf;  /* create some info to pass to find_byclass */
965     regmatch_info *const reginfo = &reginfo_buf;
966     GET_RE_DEBUG_FLAGS_DECL;
967 
968     PERL_ARGS_ASSERT_RE_INTUIT_START;
969     PERL_UNUSED_ARG(flags);
970     PERL_UNUSED_ARG(data);
971 
972     DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
973                 "Intuit: trying to determine minimum start position...\n"));
974 
975     /* for now, assume that all substr offsets are positive. If at some point
976      * in the future someone wants to do clever things with lookbehind and
977      * -ve offsets, they'll need to fix up any code in this function
978      * which uses these offsets. See the thread beginning
979      * <20140113145929.GF27210@iabyn.com>
980      */
981     assert(prog->substrs->data[0].min_offset >= 0);
982     assert(prog->substrs->data[0].max_offset >= 0);
983     assert(prog->substrs->data[1].min_offset >= 0);
984     assert(prog->substrs->data[1].max_offset >= 0);
985     assert(prog->substrs->data[2].min_offset >= 0);
986     assert(prog->substrs->data[2].max_offset >= 0);
987 
988     /* for now, assume that if both present, that the floating substring
989      * doesn't start before the anchored substring.
990      * If you break this assumption (e.g. doing better optimisations
991      * with lookahead/behind), then you'll need to audit the code in this
992      * function carefully first
993      */
994     assert(
995             ! (  (prog->anchored_utf8 || prog->anchored_substr)
996               && (prog->float_utf8    || prog->float_substr))
997            || (prog->float_min_offset >= prog->anchored_offset));
998 
999     /* byte rather than char calculation for efficiency. It fails
1000      * to quickly reject some cases that can't match, but will reject
1001      * them later after doing full char arithmetic */
1002     if (prog->minlen > strend - strpos) {
1003         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1004 			      "  String too short...\n"));
1005 	goto fail;
1006     }
1007 
1008     RXp_MATCH_UTF8_set(prog, utf8_target);
1009     reginfo->is_utf8_target = cBOOL(utf8_target);
1010     reginfo->info_aux = NULL;
1011     reginfo->strbeg = strbeg;
1012     reginfo->strend = strend;
1013     reginfo->is_utf8_pat = cBOOL(RX_UTF8(rx));
1014     reginfo->intuit = 1;
1015     /* not actually used within intuit, but zero for safety anyway */
1016     reginfo->poscache_maxiter = 0;
1017 
1018     if (utf8_target) {
1019         if ((!prog->anchored_utf8 && prog->anchored_substr)
1020                 || (!prog->float_utf8 && prog->float_substr))
1021 	    to_utf8_substr(prog);
1022 	check = prog->check_utf8;
1023     } else {
1024 	if (!prog->check_substr && prog->check_utf8) {
1025 	    if (! to_byte_substr(prog)) {
1026                 NON_UTF8_TARGET_BUT_UTF8_REQUIRED(fail);
1027             }
1028         }
1029 	check = prog->check_substr;
1030     }
1031 
1032     /* dump the various substring data */
1033     DEBUG_OPTIMISE_MORE_r({
1034         int i;
1035         for (i=0; i<=2; i++) {
1036             SV *sv = (utf8_target ? prog->substrs->data[i].utf8_substr
1037                                   : prog->substrs->data[i].substr);
1038             if (!sv)
1039                 continue;
1040 
1041             Perl_re_printf( aTHX_
1042                 "  substrs[%d]: min=%" IVdf " max=%" IVdf " end shift=%" IVdf
1043                 " useful=%" IVdf " utf8=%d [%s]\n",
1044                 i,
1045                 (IV)prog->substrs->data[i].min_offset,
1046                 (IV)prog->substrs->data[i].max_offset,
1047                 (IV)prog->substrs->data[i].end_shift,
1048                 BmUSEFUL(sv),
1049                 utf8_target ? 1 : 0,
1050                 SvPEEK(sv));
1051         }
1052     });
1053 
1054     if (prog->intflags & PREGf_ANCH) { /* Match at \G, beg-of-str or after \n */
1055 
1056         /* ml_anch: check after \n?
1057          *
1058          * A note about PREGf_IMPLICIT: on an un-anchored pattern beginning
1059          * with /.*.../, these flags will have been added by the
1060          * compiler:
1061          *   /.*abc/, /.*abc/m:  PREGf_IMPLICIT | PREGf_ANCH_MBOL
1062          *   /.*abc/s:           PREGf_IMPLICIT | PREGf_ANCH_SBOL
1063          */
1064 	ml_anch =      (prog->intflags & PREGf_ANCH_MBOL)
1065                    && !(prog->intflags & PREGf_IMPLICIT);
1066 
1067 	if (!ml_anch && !(prog->intflags & PREGf_IMPLICIT)) {
1068             /* we are only allowed to match at BOS or \G */
1069 
1070             /* trivially reject if there's a BOS anchor and we're not at BOS.
1071              *
1072              * Note that we don't try to do a similar quick reject for
1073              * \G, since generally the caller will have calculated strpos
1074              * based on pos() and gofs, so the string is already correctly
1075              * anchored by definition; and handling the exceptions would
1076              * be too fiddly (e.g. REXEC_IGNOREPOS).
1077              */
1078             if (   strpos != strbeg
1079                 && (prog->intflags & PREGf_ANCH_SBOL))
1080             {
1081                 DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1082                                 "  Not at start...\n"));
1083 	        goto fail;
1084 	    }
1085 
1086             /* in the presence of an anchor, the anchored (relative to the
1087              * start of the regex) substr must also be anchored relative
1088              * to strpos. So quickly reject if substr isn't found there.
1089              * This works for \G too, because the caller will already have
1090              * subtracted gofs from pos, and gofs is the offset from the
1091              * \G to the start of the regex. For example, in /.abc\Gdef/,
1092              * where substr="abcdef", pos()=3, gofs=4, offset_min=1:
1093              * caller will have set strpos=pos()-4; we look for the substr
1094              * at position pos()-4+1, which lines up with the "a" */
1095 
1096 	    if (prog->check_offset_min == prog->check_offset_max) {
1097 	        /* Substring at constant offset from beg-of-str... */
1098 	        SSize_t slen = SvCUR(check);
1099                 char *s = HOP3c(strpos, prog->check_offset_min, strend);
1100 
1101                 DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1102                     "  Looking for check substr at fixed offset %" IVdf "...\n",
1103                     (IV)prog->check_offset_min));
1104 
1105 	        if (SvTAIL(check)) {
1106                     /* In this case, the regex is anchored at the end too.
1107                      * Unless it's a multiline match, the lengths must match
1108                      * exactly, give or take a \n.  NB: slen >= 1 since
1109                      * the last char of check is \n */
1110 		    if (!multiline
1111                         && (   strend - s > slen
1112                             || strend - s < slen - 1
1113                             || (strend - s == slen && strend[-1] != '\n')))
1114                     {
1115                         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1116                                             "  String too long...\n"));
1117                         goto fail_finish;
1118                     }
1119                     /* Now should match s[0..slen-2] */
1120                     slen--;
1121                 }
1122                 if (slen && (strend - s < slen
1123                     || *SvPVX_const(check) != *s
1124                     || (slen > 1 && (memNE(SvPVX_const(check), s, slen)))))
1125                 {
1126                     DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1127                                     "  String not equal...\n"));
1128                     goto fail_finish;
1129                 }
1130 
1131                 check_at = s;
1132                 goto success_at_start;
1133 	    }
1134 	}
1135     }
1136 
1137     end_shift = prog->check_end_shift;
1138 
1139 #ifdef DEBUGGING	/* 7/99: reports of failure (with the older version) */
1140     if (end_shift < 0)
1141 	Perl_croak(aTHX_ "panic: end_shift: %" IVdf " pattern:\n%s\n ",
1142 		   (IV)end_shift, RX_PRECOMP(rx));
1143 #endif
1144 
1145   restart:
1146 
1147     /* This is the (re)entry point of the main loop in this function.
1148      * The goal of this loop is to:
1149      * 1) find the "check" substring in the region rx_origin..strend
1150      *    (adjusted by start_shift / end_shift). If not found, reject
1151      *    immediately.
1152      * 2) If it exists, look for the "other" substr too if defined; for
1153      *    example, if the check substr maps to the anchored substr, then
1154      *    check the floating substr, and vice-versa. If not found, go
1155      *    back to (1) with rx_origin suitably incremented.
1156      * 3) If we find an rx_origin position that doesn't contradict
1157      *    either of the substrings, then check the possible additional
1158      *    constraints on rx_origin of /^.../m or a known start class.
1159      *    If these fail, then depending on which constraints fail, jump
1160      *    back to here, or to various other re-entry points further along
1161      *    that skip some of the first steps.
1162      * 4) If we pass all those tests, update the BmUSEFUL() count on the
1163      *    substring. If the start position was determined to be at the
1164      *    beginning of the string  - so, not rejected, but not optimised,
1165      *    since we have to run regmatch from position 0 - decrement the
1166      *    BmUSEFUL() count. Otherwise increment it.
1167      */
1168 
1169 
1170     /* first, look for the 'check' substring */
1171 
1172     {
1173         U8* start_point;
1174         U8* end_point;
1175 
1176         DEBUG_OPTIMISE_MORE_r({
1177             Perl_re_printf( aTHX_
1178                 "  At restart: rx_origin=%" IVdf " Check offset min: %" IVdf
1179                 " Start shift: %" IVdf " End shift %" IVdf
1180                 " Real end Shift: %" IVdf "\n",
1181                 (IV)(rx_origin - strbeg),
1182                 (IV)prog->check_offset_min,
1183                 (IV)start_shift,
1184                 (IV)end_shift,
1185                 (IV)prog->check_end_shift);
1186         });
1187 
1188         end_point = HOPBACK3(strend, end_shift, rx_origin);
1189         if (!end_point)
1190             goto fail_finish;
1191         start_point = HOPMAYBE3(rx_origin, start_shift, end_point);
1192         if (!start_point)
1193             goto fail_finish;
1194 
1195 
1196         /* If the regex is absolutely anchored to either the start of the
1197          * string (SBOL) or to pos() (ANCH_GPOS), then
1198          * check_offset_max represents an upper bound on the string where
1199          * the substr could start. For the ANCH_GPOS case, we assume that
1200          * the caller of intuit will have already set strpos to
1201          * pos()-gofs, so in this case strpos + offset_max will still be
1202          * an upper bound on the substr.
1203          */
1204         if (!ml_anch
1205             && prog->intflags & PREGf_ANCH
1206             && prog->check_offset_max != SSize_t_MAX)
1207         {
1208             SSize_t check_len = SvCUR(check) - !!SvTAIL(check);
1209             const char * const anchor =
1210                         (prog->intflags & PREGf_ANCH_GPOS ? strpos : strbeg);
1211             SSize_t targ_len = (char*)end_point - anchor;
1212 
1213             if (check_len > targ_len) {
1214                 DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1215 			      "Target string too short to match required substring...\n"));
1216                 goto fail_finish;
1217             }
1218 
1219             /* do a bytes rather than chars comparison. It's conservative;
1220              * so it skips doing the HOP if the result can't possibly end
1221              * up earlier than the old value of end_point.
1222              */
1223             assert(anchor + check_len <= (char *)end_point);
1224             if (prog->check_offset_max + check_len < targ_len) {
1225                 end_point = HOP3lim((U8*)anchor,
1226                                 prog->check_offset_max,
1227                                 end_point - check_len
1228                             )
1229                             + check_len;
1230                 if (end_point < start_point)
1231                     goto fail_finish;
1232             }
1233         }
1234 
1235 	check_at = fbm_instr( start_point, end_point,
1236 		      check, multiline ? FBMrf_MULTILINE : 0);
1237 
1238         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1239             "  doing 'check' fbm scan, [%" IVdf "..%" IVdf "] gave %" IVdf "\n",
1240             (IV)((char*)start_point - strbeg),
1241             (IV)((char*)end_point   - strbeg),
1242             (IV)(check_at ? check_at - strbeg : -1)
1243         ));
1244 
1245         /* Update the count-of-usability, remove useless subpatterns,
1246             unshift s.  */
1247 
1248         DEBUG_EXECUTE_r({
1249             RE_PV_QUOTED_DECL(quoted, utf8_target, PERL_DEBUG_PAD_ZERO(0),
1250                 SvPVX_const(check), RE_SV_DUMPLEN(check), 30);
1251             Perl_re_printf( aTHX_  "  %s %s substr %s%s%s",
1252                               (check_at ? "Found" : "Did not find"),
1253                 (check == (utf8_target ? prog->anchored_utf8 : prog->anchored_substr)
1254                     ? "anchored" : "floating"),
1255                 quoted,
1256                 RE_SV_TAIL(check),
1257                 (check_at ? " at offset " : "...\n") );
1258         });
1259 
1260         if (!check_at)
1261             goto fail_finish;
1262         /* set rx_origin to the minimum position where the regex could start
1263          * matching, given the constraint of the just-matched check substring.
1264          * But don't set it lower than previously.
1265          */
1266 
1267         if (check_at - rx_origin > prog->check_offset_max)
1268             rx_origin = HOP3c(check_at, -prog->check_offset_max, rx_origin);
1269         /* Finish the diagnostic message */
1270         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1271             "%ld (rx_origin now %" IVdf ")...\n",
1272             (long)(check_at - strbeg),
1273             (IV)(rx_origin - strbeg)
1274         ));
1275     }
1276 
1277 
1278     /* now look for the 'other' substring if defined */
1279 
1280     if (utf8_target ? prog->substrs->data[other_ix].utf8_substr
1281                     : prog->substrs->data[other_ix].substr)
1282     {
1283 	/* Take into account the "other" substring. */
1284         char *last, *last1;
1285         char *s;
1286         SV* must;
1287         struct reg_substr_datum *other;
1288 
1289       do_other_substr:
1290         other = &prog->substrs->data[other_ix];
1291 
1292         /* if "other" is anchored:
1293          * we've previously found a floating substr starting at check_at.
1294          * This means that the regex origin must lie somewhere
1295          * between min (rx_origin): HOP3(check_at, -check_offset_max)
1296          * and max:                 HOP3(check_at, -check_offset_min)
1297          * (except that min will be >= strpos)
1298          * So the fixed  substr must lie somewhere between
1299          *  HOP3(min, anchored_offset)
1300          *  HOP3(max, anchored_offset) + SvCUR(substr)
1301          */
1302 
1303         /* if "other" is floating
1304          * Calculate last1, the absolute latest point where the
1305          * floating substr could start in the string, ignoring any
1306          * constraints from the earlier fixed match. It is calculated
1307          * as follows:
1308          *
1309          * strend - prog->minlen (in chars) is the absolute latest
1310          * position within the string where the origin of the regex
1311          * could appear. The latest start point for the floating
1312          * substr is float_min_offset(*) on from the start of the
1313          * regex.  last1 simply combines thee two offsets.
1314          *
1315          * (*) You might think the latest start point should be
1316          * float_max_offset from the regex origin, and technically
1317          * you'd be correct. However, consider
1318          *    /a\d{2,4}bcd\w/
1319          * Here, float min, max are 3,5 and minlen is 7.
1320          * This can match either
1321          *    /a\d\dbcd\w/
1322          *    /a\d\d\dbcd\w/
1323          *    /a\d\d\d\dbcd\w/
1324          * In the first case, the regex matches minlen chars; in the
1325          * second, minlen+1, in the third, minlen+2.
1326          * In the first case, the floating offset is 3 (which equals
1327          * float_min), in the second, 4, and in the third, 5 (which
1328          * equals float_max). In all cases, the floating string bcd
1329          * can never start more than 4 chars from the end of the
1330          * string, which equals minlen - float_min. As the substring
1331          * starts to match more than float_min from the start of the
1332          * regex, it makes the regex match more than minlen chars,
1333          * and the two cancel each other out. So we can always use
1334          * float_min - minlen, rather than float_max - minlen for the
1335          * latest position in the string.
1336          *
1337          * Note that -minlen + float_min_offset is equivalent (AFAIKT)
1338          * to CHR_SVLEN(must) - !!SvTAIL(must) + prog->float_end_shift
1339          */
1340 
1341         assert(prog->minlen >= other->min_offset);
1342         last1 = HOP3c(strend,
1343                         other->min_offset - prog->minlen, strbeg);
1344 
1345         if (other_ix) {/* i.e. if (other-is-float) */
1346             /* last is the latest point where the floating substr could
1347              * start, *given* any constraints from the earlier fixed
1348              * match. This constraint is that the floating string starts
1349              * <= float_max_offset chars from the regex origin (rx_origin).
1350              * If this value is less than last1, use it instead.
1351              */
1352             assert(rx_origin <= last1);
1353             last =
1354                 /* this condition handles the offset==infinity case, and
1355                  * is a short-cut otherwise. Although it's comparing a
1356                  * byte offset to a char length, it does so in a safe way,
1357                  * since 1 char always occupies 1 or more bytes,
1358                  * so if a string range is  (last1 - rx_origin) bytes,
1359                  * it will be less than or equal to  (last1 - rx_origin)
1360                  * chars; meaning it errs towards doing the accurate HOP3
1361                  * rather than just using last1 as a short-cut */
1362                 (last1 - rx_origin) < other->max_offset
1363                     ? last1
1364                     : (char*)HOP3lim(rx_origin, other->max_offset, last1);
1365         }
1366         else {
1367             assert(strpos + start_shift <= check_at);
1368             last = HOP4c(check_at, other->min_offset - start_shift,
1369                         strbeg, strend);
1370         }
1371 
1372         s = HOP3c(rx_origin, other->min_offset, strend);
1373         if (s < other_last)	/* These positions already checked */
1374             s = other_last;
1375 
1376         must = utf8_target ? other->utf8_substr : other->substr;
1377         assert(SvPOK(must));
1378         {
1379             char *from = s;
1380             char *to   = last + SvCUR(must) - (SvTAIL(must)!=0);
1381 
1382             if (to > strend)
1383                 to = strend;
1384             if (from > to) {
1385                 s = NULL;
1386                 DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1387                     "  skipping 'other' fbm scan: %" IVdf " > %" IVdf "\n",
1388                     (IV)(from - strbeg),
1389                     (IV)(to   - strbeg)
1390                 ));
1391             }
1392             else {
1393                 s = fbm_instr(
1394                     (unsigned char*)from,
1395                     (unsigned char*)to,
1396                     must,
1397                     multiline ? FBMrf_MULTILINE : 0
1398                 );
1399                 DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1400                     "  doing 'other' fbm scan, [%" IVdf "..%" IVdf "] gave %" IVdf "\n",
1401                     (IV)(from - strbeg),
1402                     (IV)(to   - strbeg),
1403                     (IV)(s ? s - strbeg : -1)
1404                 ));
1405             }
1406         }
1407 
1408         DEBUG_EXECUTE_r({
1409             RE_PV_QUOTED_DECL(quoted, utf8_target, PERL_DEBUG_PAD_ZERO(0),
1410                 SvPVX_const(must), RE_SV_DUMPLEN(must), 30);
1411             Perl_re_printf( aTHX_  "  %s %s substr %s%s",
1412                 s ? "Found" : "Contradicts",
1413                 other_ix ? "floating" : "anchored",
1414                 quoted, RE_SV_TAIL(must));
1415         });
1416 
1417 
1418         if (!s) {
1419             /* last1 is latest possible substr location. If we didn't
1420              * find it before there, we never will */
1421             if (last >= last1) {
1422                 DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1423                                         "; giving up...\n"));
1424                 goto fail_finish;
1425             }
1426 
1427             /* try to find the check substr again at a later
1428              * position. Maybe next time we'll find the "other" substr
1429              * in range too */
1430             other_last = HOP3c(last, 1, strend) /* highest failure */;
1431             rx_origin =
1432                 other_ix /* i.e. if other-is-float */
1433                     ? HOP3c(rx_origin, 1, strend)
1434                     : HOP4c(last, 1 - other->min_offset, strbeg, strend);
1435             DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1436                 "; about to retry %s at offset %ld (rx_origin now %" IVdf ")...\n",
1437                 (other_ix ? "floating" : "anchored"),
1438                 (long)(HOP3c(check_at, 1, strend) - strbeg),
1439                 (IV)(rx_origin - strbeg)
1440             ));
1441             goto restart;
1442         }
1443         else {
1444             if (other_ix) { /* if (other-is-float) */
1445                 /* other_last is set to s, not s+1, since its possible for
1446                  * a floating substr to fail first time, then succeed
1447                  * second time at the same floating position; e.g.:
1448                  *     "-AB--AABZ" =~ /\wAB\d*Z/
1449                  * The first time round, anchored and float match at
1450                  * "-(AB)--AAB(Z)" then fail on the initial \w character
1451                  * class. Second time round, they match at "-AB--A(AB)(Z)".
1452                  */
1453                 other_last = s;
1454             }
1455             else {
1456                 rx_origin = HOP3c(s, -other->min_offset, strbeg);
1457                 other_last = HOP3c(s, 1, strend);
1458             }
1459             DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1460                 " at offset %ld (rx_origin now %" IVdf ")...\n",
1461                   (long)(s - strbeg),
1462                 (IV)(rx_origin - strbeg)
1463               ));
1464 
1465         }
1466     }
1467     else {
1468         DEBUG_OPTIMISE_MORE_r(
1469             Perl_re_printf( aTHX_
1470                 "  Check-only match: offset min:%" IVdf " max:%" IVdf
1471                 " check_at:%" IVdf " rx_origin:%" IVdf " rx_origin-check_at:%" IVdf
1472                 " strend:%" IVdf "\n",
1473                 (IV)prog->check_offset_min,
1474                 (IV)prog->check_offset_max,
1475                 (IV)(check_at-strbeg),
1476                 (IV)(rx_origin-strbeg),
1477                 (IV)(rx_origin-check_at),
1478                 (IV)(strend-strbeg)
1479             )
1480         );
1481     }
1482 
1483   postprocess_substr_matches:
1484 
1485     /* handle the extra constraint of /^.../m if present */
1486 
1487     if (ml_anch && rx_origin != strbeg && rx_origin[-1] != '\n') {
1488         char *s;
1489 
1490         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1491                         "  looking for /^/m anchor"));
1492 
1493         /* we have failed the constraint of a \n before rx_origin.
1494          * Find the next \n, if any, even if it's beyond the current
1495          * anchored and/or floating substrings. Whether we should be
1496          * scanning ahead for the next \n or the next substr is debatable.
1497          * On the one hand you'd expect rare substrings to appear less
1498          * often than \n's. On the other hand, searching for \n means
1499          * we're effectively flipping between check_substr and "\n" on each
1500          * iteration as the current "rarest" string candidate, which
1501          * means for example that we'll quickly reject the whole string if
1502          * hasn't got a \n, rather than trying every substr position
1503          * first
1504          */
1505 
1506         s = HOP3c(strend, - prog->minlen, strpos);
1507         if (s <= rx_origin ||
1508             ! ( rx_origin = (char *)memchr(rx_origin, '\n', s - rx_origin)))
1509         {
1510             DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1511                             "  Did not find /%s^%s/m...\n",
1512                             PL_colors[0], PL_colors[1]));
1513             goto fail_finish;
1514         }
1515 
1516         /* earliest possible origin is 1 char after the \n.
1517          * (since *rx_origin == '\n', it's safe to ++ here rather than
1518          * HOP(rx_origin, 1)) */
1519         rx_origin++;
1520 
1521         if (prog->substrs->check_ix == 0  /* check is anchored */
1522             || rx_origin >= HOP3c(check_at,  - prog->check_offset_min, strpos))
1523         {
1524             /* Position contradicts check-string; either because
1525              * check was anchored (and thus has no wiggle room),
1526              * or check was float and rx_origin is above the float range */
1527             DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1528                 "  Found /%s^%s/m, about to restart lookup for check-string with rx_origin %ld...\n",
1529                 PL_colors[0], PL_colors[1], (long)(rx_origin - strbeg)));
1530             goto restart;
1531         }
1532 
1533         /* if we get here, the check substr must have been float,
1534          * is in range, and we may or may not have had an anchored
1535          * "other" substr which still contradicts */
1536         assert(prog->substrs->check_ix); /* check is float */
1537 
1538         if (utf8_target ? prog->anchored_utf8 : prog->anchored_substr) {
1539             /* whoops, the anchored "other" substr exists, so we still
1540              * contradict. On the other hand, the float "check" substr
1541              * didn't contradict, so just retry the anchored "other"
1542              * substr */
1543             DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1544                 "  Found /%s^%s/m, rescanning for anchored from offset %" IVdf " (rx_origin now %" IVdf ")...\n",
1545                 PL_colors[0], PL_colors[1],
1546                 (IV)(rx_origin - strbeg + prog->anchored_offset),
1547                 (IV)(rx_origin - strbeg)
1548             ));
1549             goto do_other_substr;
1550         }
1551 
1552         /* success: we don't contradict the found floating substring
1553          * (and there's no anchored substr). */
1554         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1555             "  Found /%s^%s/m with rx_origin %ld...\n",
1556             PL_colors[0], PL_colors[1], (long)(rx_origin - strbeg)));
1557     }
1558     else {
1559         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1560             "  (multiline anchor test skipped)\n"));
1561     }
1562 
1563   success_at_start:
1564 
1565 
1566     /* if we have a starting character class, then test that extra constraint.
1567      * (trie stclasses are too expensive to use here, we are better off to
1568      * leave it to regmatch itself) */
1569 
1570     if (progi->regstclass && PL_regkind[OP(progi->regstclass)]!=TRIE) {
1571         const U8* const str = (U8*)STRING(progi->regstclass);
1572 
1573         /* XXX this value could be pre-computed */
1574         const int cl_l = (PL_regkind[OP(progi->regstclass)] == EXACT
1575 		    ?  (reginfo->is_utf8_pat
1576                         ? utf8_distance(str + STR_LEN(progi->regstclass), str)
1577                         : STR_LEN(progi->regstclass))
1578 		    : 1);
1579 	char * endpos;
1580         char *s;
1581         /* latest pos that a matching float substr constrains rx start to */
1582         char *rx_max_float = NULL;
1583 
1584         /* if the current rx_origin is anchored, either by satisfying an
1585          * anchored substring constraint, or a /^.../m constraint, then we
1586          * can reject the current origin if the start class isn't found
1587          * at the current position. If we have a float-only match, then
1588          * rx_origin is constrained to a range; so look for the start class
1589          * in that range. if neither, then look for the start class in the
1590          * whole rest of the string */
1591 
1592         /* XXX DAPM it's not clear what the minlen test is for, and why
1593          * it's not used in the floating case. Nothing in the test suite
1594          * causes minlen == 0 here. See <20140313134639.GS12844@iabyn.com>.
1595          * Here are some old comments, which may or may not be correct:
1596          *
1597 	 *   minlen == 0 is possible if regstclass is \b or \B,
1598 	 *   and the fixed substr is ''$.
1599          *   Since minlen is already taken into account, rx_origin+1 is
1600          *   before strend; accidentally, minlen >= 1 guaranties no false
1601          *   positives at rx_origin + 1 even for \b or \B.  But (minlen? 1 :
1602          *   0) below assumes that regstclass does not come from lookahead...
1603 	 *   If regstclass takes bytelength more than 1: If charlength==1, OK.
1604          *   This leaves EXACTF-ish only, which are dealt with in
1605          *   find_byclass().
1606          */
1607 
1608 	if (prog->anchored_substr || prog->anchored_utf8 || ml_anch)
1609             endpos = HOP3clim(rx_origin, (prog->minlen ? cl_l : 0), strend);
1610         else if (prog->float_substr || prog->float_utf8) {
1611 	    rx_max_float = HOP3c(check_at, -start_shift, strbeg);
1612 	    endpos = HOP3clim(rx_max_float, cl_l, strend);
1613         }
1614         else
1615             endpos= strend;
1616 
1617         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1618             "  looking for class: start_shift: %" IVdf " check_at: %" IVdf
1619             " rx_origin: %" IVdf " endpos: %" IVdf "\n",
1620               (IV)start_shift, (IV)(check_at - strbeg),
1621               (IV)(rx_origin - strbeg), (IV)(endpos - strbeg)));
1622 
1623         s = find_byclass(prog, progi->regstclass, rx_origin, endpos,
1624                             reginfo);
1625 	if (!s) {
1626 	    if (endpos == strend) {
1627                 DEBUG_EXECUTE_r( Perl_re_printf( aTHX_
1628 				"  Could not match STCLASS...\n") );
1629 		goto fail;
1630 	    }
1631             DEBUG_EXECUTE_r( Perl_re_printf( aTHX_
1632                                "  This position contradicts STCLASS...\n") );
1633             if ((prog->intflags & PREGf_ANCH) && !ml_anch
1634                         && !(prog->intflags & PREGf_IMPLICIT))
1635 		goto fail;
1636 
1637 	    /* Contradict one of substrings */
1638 	    if (prog->anchored_substr || prog->anchored_utf8) {
1639                 if (prog->substrs->check_ix == 1) { /* check is float */
1640                     /* Have both, check_string is floating */
1641                     assert(rx_origin + start_shift <= check_at);
1642                     if (rx_origin + start_shift != check_at) {
1643                         /* not at latest position float substr could match:
1644                          * Recheck anchored substring, but not floating.
1645                          * The condition above is in bytes rather than
1646                          * chars for efficiency. It's conservative, in
1647                          * that it errs on the side of doing 'goto
1648                          * do_other_substr'. In this case, at worst,
1649                          * an extra anchored search may get done, but in
1650                          * practice the extra fbm_instr() is likely to
1651                          * get skipped anyway. */
1652                         DEBUG_EXECUTE_r( Perl_re_printf( aTHX_
1653                             "  about to retry anchored at offset %ld (rx_origin now %" IVdf ")...\n",
1654                             (long)(other_last - strbeg),
1655                             (IV)(rx_origin - strbeg)
1656                         ));
1657                         goto do_other_substr;
1658                     }
1659                 }
1660             }
1661 	    else {
1662                 /* float-only */
1663 
1664                 if (ml_anch) {
1665                     /* In the presence of ml_anch, we might be able to
1666                      * find another \n without breaking the current float
1667                      * constraint. */
1668 
1669                     /* strictly speaking this should be HOP3c(..., 1, ...),
1670                      * but since we goto a block of code that's going to
1671                      * search for the next \n if any, its safe here */
1672                     rx_origin++;
1673                     DEBUG_EXECUTE_r( Perl_re_printf( aTHX_
1674                               "  about to look for /%s^%s/m starting at rx_origin %ld...\n",
1675                               PL_colors[0], PL_colors[1],
1676                               (long)(rx_origin - strbeg)) );
1677                     goto postprocess_substr_matches;
1678                 }
1679 
1680                 /* strictly speaking this can never be true; but might
1681                  * be if we ever allow intuit without substrings */
1682                 if (!(utf8_target ? prog->float_utf8 : prog->float_substr))
1683                     goto fail;
1684 
1685                 rx_origin = rx_max_float;
1686             }
1687 
1688             /* at this point, any matching substrings have been
1689              * contradicted. Start again... */
1690 
1691             rx_origin = HOP3c(rx_origin, 1, strend);
1692 
1693             /* uses bytes rather than char calculations for efficiency.
1694              * It's conservative: it errs on the side of doing 'goto restart',
1695              * where there is code that does a proper char-based test */
1696             if (rx_origin + start_shift + end_shift > strend) {
1697                 DEBUG_EXECUTE_r( Perl_re_printf( aTHX_
1698                                        "  Could not match STCLASS...\n") );
1699                 goto fail;
1700             }
1701             DEBUG_EXECUTE_r( Perl_re_printf( aTHX_
1702                 "  about to look for %s substr starting at offset %ld (rx_origin now %" IVdf ")...\n",
1703                 (prog->substrs->check_ix ? "floating" : "anchored"),
1704                 (long)(rx_origin + start_shift - strbeg),
1705                 (IV)(rx_origin - strbeg)
1706             ));
1707             goto restart;
1708 	}
1709 
1710         /* Success !!! */
1711 
1712 	if (rx_origin != s) {
1713             DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1714 			"  By STCLASS: moving %ld --> %ld\n",
1715                                   (long)(rx_origin - strbeg), (long)(s - strbeg))
1716                    );
1717         }
1718         else {
1719             DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1720                                   "  Does not contradict STCLASS...\n");
1721                    );
1722         }
1723     }
1724 
1725     /* Decide whether using the substrings helped */
1726 
1727     if (rx_origin != strpos) {
1728 	/* Fixed substring is found far enough so that the match
1729 	   cannot start at strpos. */
1730 
1731         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_  "  try at offset...\n"));
1732 	++BmUSEFUL(utf8_target ? prog->check_utf8 : prog->check_substr);	/* hooray/5 */
1733     }
1734     else {
1735         /* The found rx_origin position does not prohibit matching at
1736          * strpos, so calling intuit didn't gain us anything. Decrement
1737          * the BmUSEFUL() count on the check substring, and if we reach
1738          * zero, free it.  */
1739 	if (!(prog->intflags & PREGf_NAUGHTY)
1740 	    && (utf8_target ? (
1741 		prog->check_utf8		/* Could be deleted already */
1742 		&& --BmUSEFUL(prog->check_utf8) < 0
1743 		&& (prog->check_utf8 == prog->float_utf8)
1744 	    ) : (
1745 		prog->check_substr		/* Could be deleted already */
1746 		&& --BmUSEFUL(prog->check_substr) < 0
1747 		&& (prog->check_substr == prog->float_substr)
1748 	    )))
1749 	{
1750 	    /* If flags & SOMETHING - do not do it many times on the same match */
1751             DEBUG_EXECUTE_r(Perl_re_printf( aTHX_  "  ... Disabling check substring...\n"));
1752 	    /* XXX Does the destruction order has to change with utf8_target? */
1753 	    SvREFCNT_dec(utf8_target ? prog->check_utf8 : prog->check_substr);
1754 	    SvREFCNT_dec(utf8_target ? prog->check_substr : prog->check_utf8);
1755 	    prog->check_substr = prog->check_utf8 = NULL;	/* disable */
1756 	    prog->float_substr = prog->float_utf8 = NULL;	/* clear */
1757 	    check = NULL;			/* abort */
1758 	    /* XXXX This is a remnant of the old implementation.  It
1759 	            looks wasteful, since now INTUIT can use many
1760 	            other heuristics. */
1761 	    prog->extflags &= ~RXf_USE_INTUIT;
1762 	}
1763     }
1764 
1765     DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
1766             "Intuit: %sSuccessfully guessed:%s match at offset %ld\n",
1767              PL_colors[4], PL_colors[5], (long)(rx_origin - strbeg)) );
1768 
1769     return rx_origin;
1770 
1771   fail_finish:				/* Substring not found */
1772     if (prog->check_substr || prog->check_utf8)		/* could be removed already */
1773 	BmUSEFUL(utf8_target ? prog->check_utf8 : prog->check_substr) += 5; /* hooray */
1774   fail:
1775     DEBUG_EXECUTE_r(Perl_re_printf( aTHX_  "%sMatch rejected by optimizer%s\n",
1776 			  PL_colors[4], PL_colors[5]));
1777     return NULL;
1778 }
1779 
1780 
1781 #define DECL_TRIE_TYPE(scan) \
1782     const enum { trie_plain, trie_utf8, trie_utf8_fold, trie_latin_utf8_fold,       \
1783                  trie_utf8_exactfa_fold, trie_latin_utf8_exactfa_fold,              \
1784                  trie_utf8l, trie_flu8, trie_flu8_latin }                           \
1785                     trie_type = ((scan->flags == EXACT)                             \
1786                                  ? (utf8_target ? trie_utf8 : trie_plain)           \
1787                                  : (scan->flags == EXACTL)                          \
1788                                     ? (utf8_target ? trie_utf8l : trie_plain)       \
1789                                     : (scan->flags == EXACTFAA)                     \
1790                                       ? (utf8_target                                \
1791                                          ? trie_utf8_exactfa_fold                   \
1792                                          : trie_latin_utf8_exactfa_fold)            \
1793                                       : (scan->flags == EXACTFLU8                   \
1794                                          ? (utf8_target                             \
1795                                            ? trie_flu8                              \
1796                                            : trie_flu8_latin)                       \
1797                                          : (utf8_target                             \
1798                                            ? trie_utf8_fold                         \
1799                                            : trie_latin_utf8_fold)))
1800 
1801 /* 'uscan' is set to foldbuf, and incremented, so below the end of uscan is
1802  * 'foldbuf+sizeof(foldbuf)' */
1803 #define REXEC_TRIE_READ_CHAR(trie_type, trie, widecharmap, uc, uc_end, uscan, len, uvc, charid, foldlen, foldbuf, uniflags) \
1804 STMT_START {                                                                        \
1805     STRLEN skiplen;                                                                 \
1806     U8 flags = FOLD_FLAGS_FULL;                                                     \
1807     switch (trie_type) {                                                            \
1808     case trie_flu8:                                                                 \
1809         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;                                         \
1810         if (UTF8_IS_ABOVE_LATIN1(*uc)) {                                            \
1811             _CHECK_AND_OUTPUT_WIDE_LOCALE_UTF8_MSG(uc, uc_end - uc);                \
1812         }                                                                           \
1813         goto do_trie_utf8_fold;                                                     \
1814     case trie_utf8_exactfa_fold:                                                    \
1815         flags |= FOLD_FLAGS_NOMIX_ASCII;                                            \
1816         /* FALLTHROUGH */                                                           \
1817     case trie_utf8_fold:                                                            \
1818       do_trie_utf8_fold:                                                            \
1819         if ( foldlen>0 ) {                                                          \
1820             uvc = utf8n_to_uvchr( (const U8*) uscan, foldlen, &len, uniflags );     \
1821             foldlen -= len;                                                         \
1822             uscan += len;                                                           \
1823             len=0;                                                                  \
1824         } else {                                                                    \
1825             uvc = _toFOLD_utf8_flags( (const U8*) uc, uc_end, foldbuf, &foldlen,    \
1826                                                                             flags); \
1827             len = UTF8SKIP(uc);                                                     \
1828             skiplen = UVCHR_SKIP( uvc );                                            \
1829             foldlen -= skiplen;                                                     \
1830             uscan = foldbuf + skiplen;                                              \
1831         }                                                                           \
1832         break;                                                                      \
1833     case trie_flu8_latin:                                                           \
1834         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;                                         \
1835         goto do_trie_latin_utf8_fold;                                               \
1836     case trie_latin_utf8_exactfa_fold:                                              \
1837         flags |= FOLD_FLAGS_NOMIX_ASCII;                                            \
1838         /* FALLTHROUGH */                                                           \
1839     case trie_latin_utf8_fold:                                                      \
1840       do_trie_latin_utf8_fold:                                                      \
1841         if ( foldlen>0 ) {                                                          \
1842             uvc = utf8n_to_uvchr( (const U8*) uscan, foldlen, &len, uniflags );     \
1843             foldlen -= len;                                                         \
1844             uscan += len;                                                           \
1845             len=0;                                                                  \
1846         } else {                                                                    \
1847             len = 1;                                                                \
1848             uvc = _to_fold_latin1( (U8) *uc, foldbuf, &foldlen, flags);             \
1849             skiplen = UVCHR_SKIP( uvc );                                            \
1850             foldlen -= skiplen;                                                     \
1851             uscan = foldbuf + skiplen;                                              \
1852         }                                                                           \
1853         break;                                                                      \
1854     case trie_utf8l:                                                                \
1855         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;                                         \
1856         if (utf8_target && UTF8_IS_ABOVE_LATIN1(*uc)) {                             \
1857             _CHECK_AND_OUTPUT_WIDE_LOCALE_UTF8_MSG(uc, uc + UTF8SKIP(uc));          \
1858         }                                                                           \
1859         /* FALLTHROUGH */                                                           \
1860     case trie_utf8:                                                                 \
1861         uvc = utf8n_to_uvchr( (const U8*) uc, uc_end - uc, &len, uniflags );        \
1862         break;                                                                      \
1863     case trie_plain:                                                                \
1864         uvc = (UV)*uc;                                                              \
1865         len = 1;                                                                    \
1866     }                                                                               \
1867     if (uvc < 256) {                                                                \
1868         charid = trie->charmap[ uvc ];                                              \
1869     }                                                                               \
1870     else {                                                                          \
1871         charid = 0;                                                                 \
1872         if (widecharmap) {                                                          \
1873             SV** const svpp = hv_fetch(widecharmap,                                 \
1874                         (char*)&uvc, sizeof(UV), 0);                                \
1875             if (svpp)                                                               \
1876                 charid = (U16)SvIV(*svpp);                                          \
1877         }                                                                           \
1878     }                                                                               \
1879 } STMT_END
1880 
1881 #define DUMP_EXEC_POS(li,s,doutf8,depth)                    \
1882     dump_exec_pos(li,s,(reginfo->strend),(reginfo->strbeg), \
1883                 startpos, doutf8, depth)
1884 
1885 #define REXEC_FBC_SCAN(UTF8, CODE)                          \
1886     STMT_START {                                            \
1887         while (s < strend) {                                \
1888             CODE                                            \
1889             s += ((UTF8) ? UTF8SKIP(s) : 1);                \
1890         }                                                   \
1891     } STMT_END
1892 
1893 #define REXEC_FBC_CLASS_SCAN(UTF8, COND)                    \
1894     STMT_START {                                            \
1895         while (s < strend) {                                \
1896             REXEC_FBC_CLASS_SCAN_GUTS(UTF8, COND)           \
1897         }                                                   \
1898     } STMT_END
1899 
1900 #define REXEC_FBC_CLASS_SCAN_GUTS(UTF8, COND)                  \
1901     if (COND) {                                                \
1902         FBC_CHECK_AND_TRY                                      \
1903         s += ((UTF8) ? UTF8SKIP(s) : 1);                       \
1904         previous_occurrence_end = s;                           \
1905     }                                                          \
1906     else {                                                     \
1907         s += ((UTF8) ? UTF8SKIP(s) : 1);                       \
1908     }
1909 
1910 #define REXEC_FBC_CSCAN(CONDUTF8,COND)                         \
1911     if (utf8_target) {                                         \
1912 	REXEC_FBC_CLASS_SCAN(1, CONDUTF8);                     \
1913     }                                                          \
1914     else {                                                     \
1915 	REXEC_FBC_CLASS_SCAN(0, COND);                         \
1916     }
1917 
1918 /* We keep track of where the next character should start after an occurrence
1919  * of the one we're looking for.  Knowing that, we can see right away if the
1920  * next occurrence is adjacent to the previous.  When 'doevery' is FALSE, we
1921  * don't accept the 2nd and succeeding adjacent occurrences */
1922 #define FBC_CHECK_AND_TRY                                      \
1923         if (   (   doevery                                     \
1924                 || s != previous_occurrence_end)               \
1925             && (reginfo->intuit || regtry(reginfo, &s)))       \
1926         {                                                      \
1927             goto got_it;                                       \
1928         }
1929 
1930 
1931 /* This differs from the above macros in that it calls a function which returns
1932  * the next occurrence of the thing being looked for in 's'; and 'strend' if
1933  * there is no such occurrence. */
1934 #define REXEC_FBC_FIND_NEXT_SCAN(UTF8, f)                   \
1935     while (s < strend) {                                    \
1936         s = (f);                                            \
1937         if (s >= strend) {                                  \
1938             break;                                          \
1939         }                                                   \
1940                                                             \
1941         FBC_CHECK_AND_TRY                                   \
1942         s += (UTF8) ? UTF8SKIP(s) : 1;                      \
1943         previous_occurrence_end = s;                        \
1944     }
1945 
1946 /* The three macros below are slightly different versions of the same logic.
1947  *
1948  * The first is for /a and /aa when the target string is UTF-8.  This can only
1949  * match ascii, but it must advance based on UTF-8.   The other two handle the
1950  * non-UTF-8 and the more generic UTF-8 cases.   In all three, we are looking
1951  * for the boundary (or non-boundary) between a word and non-word character.
1952  * The utf8 and non-utf8 cases have the same logic, but the details must be
1953  * different.  Find the "wordness" of the character just prior to this one, and
1954  * compare it with the wordness of this one.  If they differ, we have a
1955  * boundary.  At the beginning of the string, pretend that the previous
1956  * character was a new-line.
1957  *
1958  * All these macros uncleanly have side-effects with each other and outside
1959  * variables.  So far it's been too much trouble to clean-up
1960  *
1961  * TEST_NON_UTF8 is the macro or function to call to test if its byte input is
1962  *               a word character or not.
1963  * IF_SUCCESS    is code to do if it finds that we are at a boundary between
1964  *               word/non-word
1965  * IF_FAIL       is code to do if we aren't at a boundary between word/non-word
1966  *
1967  * Exactly one of the two IF_FOO parameters is a no-op, depending on whether we
1968  * are looking for a boundary or for a non-boundary.  If we are looking for a
1969  * boundary, we want IF_FAIL to be the no-op, and for IF_SUCCESS to go out and
1970  * see if this tentative match actually works, and if so, to quit the loop
1971  * here.  And vice-versa if we are looking for a non-boundary.
1972  *
1973  * 'tmp' below in the next three macros in the REXEC_FBC_SCAN and
1974  * REXEC_FBC_SCAN loops is a loop invariant, a bool giving the return of
1975  * TEST_NON_UTF8(s-1).  To see this, note that that's what it is defined to be
1976  * at entry to the loop, and to get to the IF_FAIL branch, tmp must equal
1977  * TEST_NON_UTF8(s), and in the opposite branch, IF_SUCCESS, tmp is that
1978  * complement.  But in that branch we complement tmp, meaning that at the
1979  * bottom of the loop tmp is always going to be equal to TEST_NON_UTF8(s),
1980  * which means at the top of the loop in the next iteration, it is
1981  * TEST_NON_UTF8(s-1) */
1982 #define FBC_UTF8_A(TEST_NON_UTF8, IF_SUCCESS, IF_FAIL)                         \
1983     tmp = (s != reginfo->strbeg) ? UCHARAT(s - 1) : '\n';                      \
1984     tmp = TEST_NON_UTF8(tmp);                                                  \
1985     REXEC_FBC_SCAN(1,  /* 1=>is-utf8; advances s while s < strend */           \
1986         if (tmp == ! TEST_NON_UTF8((U8) *s)) {                                 \
1987             tmp = !tmp;                                                        \
1988             IF_SUCCESS; /* Is a boundary if values for s-1 and s differ */     \
1989         }                                                                      \
1990         else {                                                                 \
1991             IF_FAIL;                                                           \
1992         }                                                                      \
1993     );                                                                         \
1994 
1995 /* Like FBC_UTF8_A, but TEST_UV is a macro which takes a UV as its input, and
1996  * TEST_UTF8 is a macro that for the same input code points returns identically
1997  * to TEST_UV, but takes a pointer to a UTF-8 encoded string instead */
1998 #define FBC_UTF8(TEST_UV, TEST_UTF8, IF_SUCCESS, IF_FAIL)                      \
1999     if (s == reginfo->strbeg) {                                                \
2000         tmp = '\n';                                                            \
2001     }                                                                          \
2002     else { /* Back-up to the start of the previous character */                \
2003         U8 * const r = reghop3((U8*)s, -1, (U8*)reginfo->strbeg);              \
2004         tmp = utf8n_to_uvchr(r, (U8*) reginfo->strend - r,                     \
2005                                                        0, UTF8_ALLOW_DEFAULT); \
2006     }                                                                          \
2007     tmp = TEST_UV(tmp);                                                        \
2008     REXEC_FBC_SCAN(1,  /* 1=>is-utf8; advances s while s < strend */           \
2009         if (tmp == ! (TEST_UTF8((U8 *) s, (U8 *) reginfo->strend))) {          \
2010             tmp = !tmp;                                                        \
2011             IF_SUCCESS;                                                        \
2012         }                                                                      \
2013         else {                                                                 \
2014             IF_FAIL;                                                           \
2015         }                                                                      \
2016     );
2017 
2018 /* Like the above two macros.  UTF8_CODE is the complete code for handling
2019  * UTF-8.  Common to the BOUND and NBOUND cases, set-up by the FBC_BOUND, etc
2020  * macros below */
2021 #define FBC_BOUND_COMMON(UTF8_CODE, TEST_NON_UTF8, IF_SUCCESS, IF_FAIL)        \
2022     if (utf8_target) {                                                         \
2023         UTF8_CODE                                                              \
2024     }                                                                          \
2025     else {  /* Not utf8 */                                                     \
2026 	tmp = (s != reginfo->strbeg) ? UCHARAT(s - 1) : '\n';                  \
2027 	tmp = TEST_NON_UTF8(tmp);                                              \
2028 	REXEC_FBC_SCAN(0, /* 0=>not-utf8; advances s while s < strend */       \
2029 	    if (tmp == ! TEST_NON_UTF8((U8) *s)) {                             \
2030 		IF_SUCCESS;                                                    \
2031 		tmp = !tmp;                                                    \
2032 	    }                                                                  \
2033 	    else {                                                             \
2034 		IF_FAIL;                                                       \
2035 	    }                                                                  \
2036 	);                                                                     \
2037     }                                                                          \
2038     /* Here, things have been set up by the previous code so that tmp is the   \
2039      * return of TEST_NON_UTF(s-1) or TEST_UTF8(s-1) (depending on the         \
2040      * utf8ness of the target).  We also have to check if this matches against \
2041      * the EOS, which we treat as a \n (which is the same value in both UTF-8  \
2042      * or non-UTF8, so can use the non-utf8 test condition even for a UTF-8    \
2043      * string */                                                               \
2044     if (tmp == ! TEST_NON_UTF8('\n')) {                                        \
2045         IF_SUCCESS;                                                            \
2046     }                                                                          \
2047     else {                                                                     \
2048         IF_FAIL;                                                               \
2049     }
2050 
2051 /* This is the macro to use when we want to see if something that looks like it
2052  * could match, actually does, and if so exits the loop */
2053 #define REXEC_FBC_TRYIT                            \
2054     if ((reginfo->intuit || regtry(reginfo, &s)))  \
2055         goto got_it
2056 
2057 /* The only difference between the BOUND and NBOUND cases is that
2058  * REXEC_FBC_TRYIT is called when matched in BOUND, and when non-matched in
2059  * NBOUND.  This is accomplished by passing it as either the if or else clause,
2060  * with the other one being empty (PLACEHOLDER is defined as empty).
2061  *
2062  * The TEST_FOO parameters are for operating on different forms of input, but
2063  * all should be ones that return identically for the same underlying code
2064  * points */
2065 #define FBC_BOUND(TEST_NON_UTF8, TEST_UV, TEST_UTF8)                           \
2066     FBC_BOUND_COMMON(                                                          \
2067           FBC_UTF8(TEST_UV, TEST_UTF8, REXEC_FBC_TRYIT, PLACEHOLDER),          \
2068           TEST_NON_UTF8, REXEC_FBC_TRYIT, PLACEHOLDER)
2069 
2070 #define FBC_BOUND_A(TEST_NON_UTF8)                                             \
2071     FBC_BOUND_COMMON(                                                          \
2072             FBC_UTF8_A(TEST_NON_UTF8, REXEC_FBC_TRYIT, PLACEHOLDER),           \
2073             TEST_NON_UTF8, REXEC_FBC_TRYIT, PLACEHOLDER)
2074 
2075 #define FBC_NBOUND(TEST_NON_UTF8, TEST_UV, TEST_UTF8)                          \
2076     FBC_BOUND_COMMON(                                                          \
2077           FBC_UTF8(TEST_UV, TEST_UTF8, PLACEHOLDER, REXEC_FBC_TRYIT),          \
2078           TEST_NON_UTF8, PLACEHOLDER, REXEC_FBC_TRYIT)
2079 
2080 #define FBC_NBOUND_A(TEST_NON_UTF8)                                            \
2081     FBC_BOUND_COMMON(                                                          \
2082             FBC_UTF8_A(TEST_NON_UTF8, PLACEHOLDER, REXEC_FBC_TRYIT),           \
2083             TEST_NON_UTF8, PLACEHOLDER, REXEC_FBC_TRYIT)
2084 
2085 #ifdef DEBUGGING
2086 static IV
2087 S_get_break_val_cp_checked(SV* const invlist, const UV cp_in) {
2088   IV cp_out = Perl__invlist_search(invlist, cp_in);
2089   assert(cp_out >= 0);
2090   return cp_out;
2091 }
2092 #  define _generic_GET_BREAK_VAL_CP_CHECKED(invlist, invmap, cp) \
2093 	invmap[S_get_break_val_cp_checked(invlist, cp)]
2094 #else
2095 #  define _generic_GET_BREAK_VAL_CP_CHECKED(invlist, invmap, cp) \
2096 	invmap[_invlist_search(invlist, cp)]
2097 #endif
2098 
2099 /* Takes a pointer to an inversion list, a pointer to its corresponding
2100  * inversion map, and a code point, and returns the code point's value
2101  * according to the two arrays.  It assumes that all code points have a value.
2102  * This is used as the base macro for macros for particular properties */
2103 #define _generic_GET_BREAK_VAL_CP(invlist, invmap, cp)              \
2104 	_generic_GET_BREAK_VAL_CP_CHECKED(invlist, invmap, cp)
2105 
2106 /* Same as above, but takes begin, end ptrs to a UTF-8 encoded string instead
2107  * of a code point, returning the value for the first code point in the string.
2108  * And it takes the particular macro name that finds the desired value given a
2109  * code point.  Merely convert the UTF-8 to code point and call the cp macro */
2110 #define _generic_GET_BREAK_VAL_UTF8(cp_macro, pos, strend)                     \
2111              (__ASSERT_(pos < strend)                                          \
2112                  /* Note assumes is valid UTF-8 */                             \
2113              (cp_macro(utf8_to_uvchr_buf((pos), (strend), NULL))))
2114 
2115 /* Returns the GCB value for the input code point */
2116 #define getGCB_VAL_CP(cp)                                                      \
2117           _generic_GET_BREAK_VAL_CP(                                           \
2118                                     PL_GCB_invlist,                            \
2119                                     _Perl_GCB_invmap,                          \
2120                                     (cp))
2121 
2122 /* Returns the GCB value for the first code point in the UTF-8 encoded string
2123  * bounded by pos and strend */
2124 #define getGCB_VAL_UTF8(pos, strend)                                           \
2125     _generic_GET_BREAK_VAL_UTF8(getGCB_VAL_CP, pos, strend)
2126 
2127 /* Returns the LB value for the input code point */
2128 #define getLB_VAL_CP(cp)                                                       \
2129           _generic_GET_BREAK_VAL_CP(                                           \
2130                                     PL_LB_invlist,                             \
2131                                     _Perl_LB_invmap,                           \
2132                                     (cp))
2133 
2134 /* Returns the LB value for the first code point in the UTF-8 encoded string
2135  * bounded by pos and strend */
2136 #define getLB_VAL_UTF8(pos, strend)                                            \
2137     _generic_GET_BREAK_VAL_UTF8(getLB_VAL_CP, pos, strend)
2138 
2139 
2140 /* Returns the SB value for the input code point */
2141 #define getSB_VAL_CP(cp)                                                       \
2142           _generic_GET_BREAK_VAL_CP(                                           \
2143                                     PL_SB_invlist,                             \
2144                                     _Perl_SB_invmap,                     \
2145                                     (cp))
2146 
2147 /* Returns the SB value for the first code point in the UTF-8 encoded string
2148  * bounded by pos and strend */
2149 #define getSB_VAL_UTF8(pos, strend)                                            \
2150     _generic_GET_BREAK_VAL_UTF8(getSB_VAL_CP, pos, strend)
2151 
2152 /* Returns the WB value for the input code point */
2153 #define getWB_VAL_CP(cp)                                                       \
2154           _generic_GET_BREAK_VAL_CP(                                           \
2155                                     PL_WB_invlist,                             \
2156                                     _Perl_WB_invmap,                         \
2157                                     (cp))
2158 
2159 /* Returns the WB value for the first code point in the UTF-8 encoded string
2160  * bounded by pos and strend */
2161 #define getWB_VAL_UTF8(pos, strend)                                            \
2162     _generic_GET_BREAK_VAL_UTF8(getWB_VAL_CP, pos, strend)
2163 
2164 /* We know what class REx starts with.  Try to find this position... */
2165 /* if reginfo->intuit, its a dryrun */
2166 /* annoyingly all the vars in this routine have different names from their counterparts
2167    in regmatch. /grrr */
2168 STATIC char *
2169 S_find_byclass(pTHX_ regexp * prog, const regnode *c, char *s,
2170     const char *strend, regmatch_info *reginfo)
2171 {
2172     dVAR;
2173 
2174     /* TRUE if x+ need not match at just the 1st pos of run of x's */
2175     const I32 doevery = (prog->intflags & PREGf_SKIP) == 0;
2176 
2177     char *pat_string;   /* The pattern's exactish string */
2178     char *pat_end;	    /* ptr to end char of pat_string */
2179     re_fold_t folder;	/* Function for computing non-utf8 folds */
2180     const U8 *fold_array;   /* array for folding ords < 256 */
2181     STRLEN ln;
2182     STRLEN lnc;
2183     U8 c1;
2184     U8 c2;
2185     char *e;
2186 
2187     /* In some cases we accept only the first occurence of 'x' in a sequence of
2188      * them.  This variable points to just beyond the end of the previous
2189      * occurrence of 'x', hence we can tell if we are in a sequence.  (Having
2190      * it point to beyond the 'x' allows us to work for UTF-8 without having to
2191      * hop back.) */
2192     char * previous_occurrence_end = 0;
2193 
2194     I32 tmp;            /* Scratch variable */
2195     const bool utf8_target = reginfo->is_utf8_target;
2196     UV utf8_fold_flags = 0;
2197     const bool is_utf8_pat = reginfo->is_utf8_pat;
2198     bool to_complement = FALSE; /* Invert the result?  Taking the xor of this
2199                                    with a result inverts that result, as 0^1 =
2200                                    1 and 1^1 = 0 */
2201     _char_class_number classnum;
2202 
2203     RXi_GET_DECL(prog,progi);
2204 
2205     PERL_ARGS_ASSERT_FIND_BYCLASS;
2206 
2207     /* We know what class it must start with. */
2208     switch (OP(c)) {
2209     case ANYOFL:
2210         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
2211 
2212         if (ANYOFL_UTF8_LOCALE_REQD(FLAGS(c)) && ! IN_UTF8_CTYPE_LOCALE) {
2213             Perl_ck_warner(aTHX_ packWARN(WARN_LOCALE), utf8_locale_required);
2214         }
2215 
2216         /* FALLTHROUGH */
2217     case ANYOFD:
2218     case ANYOF:
2219         if (utf8_target) {
2220             REXEC_FBC_CLASS_SCAN(1, /* 1=>is-utf8 */
2221                       reginclass(prog, c, (U8*)s, (U8*) strend, utf8_target));
2222         }
2223         else if (ANYOF_FLAGS(c)) {
2224             REXEC_FBC_CLASS_SCAN(0, reginclass(prog,c, (U8*)s, (U8*)s+1, 0));
2225         }
2226         else {
2227             REXEC_FBC_CLASS_SCAN(0, ANYOF_BITMAP_TEST(c, *((U8*)s)));
2228         }
2229         break;
2230 
2231     case ANYOFM:    /* ARG() is the base byte; FLAGS() the mask byte */
2232         /* UTF-8ness doesn't matter, so use 0 */
2233         REXEC_FBC_FIND_NEXT_SCAN(0,
2234          (char *) find_next_masked((U8 *) s, (U8 *) strend,
2235                                    (U8) ARG(c), FLAGS(c)));
2236         break;
2237 
2238     case EXACTFAA_NO_TRIE: /* This node only generated for non-utf8 patterns */
2239         assert(! is_utf8_pat);
2240 	/* FALLTHROUGH */
2241     case EXACTFAA:
2242         if (is_utf8_pat || utf8_target) {
2243             utf8_fold_flags = FOLDEQ_UTF8_NOMIX_ASCII;
2244             goto do_exactf_utf8;
2245         }
2246         fold_array = PL_fold_latin1;    /* Latin1 folds are not affected by */
2247         folder = foldEQ_latin1;	        /* /a, except the sharp s one which */
2248         goto do_exactf_non_utf8;	/* isn't dealt with by these */
2249 
2250     case EXACTF:   /* This node only generated for non-utf8 patterns */
2251         assert(! is_utf8_pat);
2252         if (utf8_target) {
2253             utf8_fold_flags = 0;
2254             goto do_exactf_utf8;
2255         }
2256         fold_array = PL_fold;
2257         folder = foldEQ;
2258         goto do_exactf_non_utf8;
2259 
2260     case EXACTFL:
2261         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
2262         if (is_utf8_pat || utf8_target || IN_UTF8_CTYPE_LOCALE) {
2263             utf8_fold_flags = FOLDEQ_LOCALE;
2264             goto do_exactf_utf8;
2265         }
2266         fold_array = PL_fold_locale;
2267         folder = foldEQ_locale;
2268         goto do_exactf_non_utf8;
2269 
2270     case EXACTFU_SS:
2271         if (is_utf8_pat) {
2272             utf8_fold_flags = FOLDEQ_S2_ALREADY_FOLDED;
2273         }
2274         goto do_exactf_utf8;
2275 
2276     case EXACTFLU8:
2277             if (! utf8_target) {    /* All code points in this node require
2278                                        UTF-8 to express.  */
2279                 break;
2280             }
2281             utf8_fold_flags =  FOLDEQ_LOCALE | FOLDEQ_S2_ALREADY_FOLDED
2282                                              | FOLDEQ_S2_FOLDS_SANE;
2283             goto do_exactf_utf8;
2284 
2285     case EXACTFU:
2286         if (is_utf8_pat || utf8_target) {
2287             utf8_fold_flags = is_utf8_pat ? FOLDEQ_S2_ALREADY_FOLDED : 0;
2288             goto do_exactf_utf8;
2289         }
2290 
2291         /* Any 'ss' in the pattern should have been replaced by regcomp,
2292          * so we don't have to worry here about this single special case
2293          * in the Latin1 range */
2294         fold_array = PL_fold_latin1;
2295         folder = foldEQ_latin1;
2296 
2297         /* FALLTHROUGH */
2298 
2299       do_exactf_non_utf8: /* Neither pattern nor string are UTF8, and there
2300                            are no glitches with fold-length differences
2301                            between the target string and pattern */
2302 
2303         /* The idea in the non-utf8 EXACTF* cases is to first find the
2304          * first character of the EXACTF* node and then, if necessary,
2305          * case-insensitively compare the full text of the node.  c1 is the
2306          * first character.  c2 is its fold.  This logic will not work for
2307          * Unicode semantics and the german sharp ss, which hence should
2308          * not be compiled into a node that gets here. */
2309         pat_string = STRING(c);
2310         ln  = STR_LEN(c);	/* length to match in octets/bytes */
2311 
2312         /* We know that we have to match at least 'ln' bytes (which is the
2313          * same as characters, since not utf8).  If we have to match 3
2314          * characters, and there are only 2 availabe, we know without
2315          * trying that it will fail; so don't start a match past the
2316          * required minimum number from the far end */
2317         e = HOP3c(strend, -((SSize_t)ln), s);
2318         if (e < s)
2319             break;
2320 
2321         c1 = *pat_string;
2322         c2 = fold_array[c1];
2323         if (c1 == c2) { /* If char and fold are the same */
2324             while (s <= e) {
2325                 s = (char *) memchr(s, c1, e + 1 - s);
2326                 if (s == NULL) {
2327                     break;
2328                 }
2329 
2330                 /* Check that the rest of the node matches */
2331                 if (   (ln == 1 || folder(s + 1, pat_string + 1, ln - 1))
2332                     && (reginfo->intuit || regtry(reginfo, &s)) )
2333                 {
2334                     goto got_it;
2335                 }
2336                 s++;
2337             }
2338         }
2339         else {
2340             U8 bits_differing = c1 ^ c2;
2341 
2342             /* If the folds differ in one bit position only, we can mask to
2343              * match either of them, and can use this faster find method.  Both
2344              * ASCII and EBCDIC tend to have their case folds differ in only
2345              * one position, so this is very likely */
2346             if (LIKELY(PL_bitcount[bits_differing] == 1)) {
2347                 bits_differing = ~ bits_differing;
2348                 while (s <= e) {
2349                     s = (char *) find_next_masked((U8 *) s, (U8 *) e + 1,
2350                                         (c1 & bits_differing), bits_differing);
2351                     if (s > e) {
2352                         break;
2353                     }
2354 
2355                     if (   (ln == 1 || folder(s + 1, pat_string + 1, ln - 1))
2356                         && (reginfo->intuit || regtry(reginfo, &s)) )
2357                     {
2358                         goto got_it;
2359                     }
2360                     s++;
2361                 }
2362             }
2363             else {  /* Otherwise, stuck with looking byte-at-a-time.  This
2364                        should actually happen only in EXACTFL nodes */
2365                 while (s <= e) {
2366                     if (    (*(U8*)s == c1 || *(U8*)s == c2)
2367                         && (ln == 1 || folder(s + 1, pat_string + 1, ln - 1))
2368                         && (reginfo->intuit || regtry(reginfo, &s)) )
2369                     {
2370                         goto got_it;
2371                     }
2372                     s++;
2373                 }
2374             }
2375         }
2376         break;
2377 
2378       do_exactf_utf8:
2379       {
2380         unsigned expansion;
2381 
2382         /* If one of the operands is in utf8, we can't use the simpler folding
2383          * above, due to the fact that many different characters can have the
2384          * same fold, or portion of a fold, or different- length fold */
2385         pat_string = STRING(c);
2386         ln  = STR_LEN(c);	/* length to match in octets/bytes */
2387         pat_end = pat_string + ln;
2388         lnc = is_utf8_pat       /* length to match in characters */
2389                 ? utf8_length((U8 *) pat_string, (U8 *) pat_end)
2390                 : ln;
2391 
2392         /* We have 'lnc' characters to match in the pattern, but because of
2393          * multi-character folding, each character in the target can match
2394          * up to 3 characters (Unicode guarantees it will never exceed
2395          * this) if it is utf8-encoded; and up to 2 if not (based on the
2396          * fact that the Latin 1 folds are already determined, and the
2397          * only multi-char fold in that range is the sharp-s folding to
2398          * 'ss'.  Thus, a pattern character can match as little as 1/3 of a
2399          * string character.  Adjust lnc accordingly, rounding up, so that
2400          * if we need to match at least 4+1/3 chars, that really is 5. */
2401         expansion = (utf8_target) ? UTF8_MAX_FOLD_CHAR_EXPAND : 2;
2402         lnc = (lnc + expansion - 1) / expansion;
2403 
2404         /* As in the non-UTF8 case, if we have to match 3 characters, and
2405          * only 2 are left, it's guaranteed to fail, so don't start a
2406          * match that would require us to go beyond the end of the string
2407          */
2408         e = HOP3c(strend, -((SSize_t)lnc), s);
2409 
2410         /* XXX Note that we could recalculate e to stop the loop earlier,
2411          * as the worst case expansion above will rarely be met, and as we
2412          * go along we would usually find that e moves further to the left.
2413          * This would happen only after we reached the point in the loop
2414          * where if there were no expansion we should fail.  Unclear if
2415          * worth the expense */
2416 
2417         while (s <= e) {
2418             char *my_strend= (char *)strend;
2419             if (foldEQ_utf8_flags(s, &my_strend, 0,  utf8_target,
2420                   pat_string, NULL, ln, is_utf8_pat, utf8_fold_flags)
2421                 && (reginfo->intuit || regtry(reginfo, &s)) )
2422             {
2423                 goto got_it;
2424             }
2425             s += (utf8_target) ? UTF8SKIP(s) : 1;
2426         }
2427         break;
2428     }
2429 
2430     case BOUNDL:
2431         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
2432         if (FLAGS(c) != TRADITIONAL_BOUND) {
2433             if (! IN_UTF8_CTYPE_LOCALE) {
2434                 Perl_ck_warner(aTHX_ packWARN(WARN_LOCALE),
2435                                                 B_ON_NON_UTF8_LOCALE_IS_WRONG);
2436             }
2437             goto do_boundu;
2438         }
2439 
2440         FBC_BOUND(isWORDCHAR_LC, isWORDCHAR_LC_uvchr, isWORDCHAR_LC_utf8_safe);
2441         break;
2442 
2443     case NBOUNDL:
2444         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
2445         if (FLAGS(c) != TRADITIONAL_BOUND) {
2446             if (! IN_UTF8_CTYPE_LOCALE) {
2447                 Perl_ck_warner(aTHX_ packWARN(WARN_LOCALE),
2448                                                 B_ON_NON_UTF8_LOCALE_IS_WRONG);
2449             }
2450             goto do_nboundu;
2451         }
2452 
2453         FBC_NBOUND(isWORDCHAR_LC, isWORDCHAR_LC_uvchr, isWORDCHAR_LC_utf8_safe);
2454         break;
2455 
2456     case BOUND: /* regcomp.c makes sure that this only has the traditional \b
2457                    meaning */
2458         assert(FLAGS(c) == TRADITIONAL_BOUND);
2459 
2460         FBC_BOUND(isWORDCHAR, isWORDCHAR_uni, isWORDCHAR_utf8_safe);
2461         break;
2462 
2463     case BOUNDA: /* regcomp.c makes sure that this only has the traditional \b
2464                    meaning */
2465         assert(FLAGS(c) == TRADITIONAL_BOUND);
2466 
2467         FBC_BOUND_A(isWORDCHAR_A);
2468         break;
2469 
2470     case NBOUND: /* regcomp.c makes sure that this only has the traditional \b
2471                    meaning */
2472         assert(FLAGS(c) == TRADITIONAL_BOUND);
2473 
2474         FBC_NBOUND(isWORDCHAR, isWORDCHAR_uni, isWORDCHAR_utf8_safe);
2475         break;
2476 
2477     case NBOUNDA: /* regcomp.c makes sure that this only has the traditional \b
2478                    meaning */
2479         assert(FLAGS(c) == TRADITIONAL_BOUND);
2480 
2481         FBC_NBOUND_A(isWORDCHAR_A);
2482         break;
2483 
2484     case NBOUNDU:
2485         if ((bound_type) FLAGS(c) == TRADITIONAL_BOUND) {
2486             FBC_NBOUND(isWORDCHAR_L1, isWORDCHAR_uni, isWORDCHAR_utf8_safe);
2487             break;
2488         }
2489 
2490       do_nboundu:
2491 
2492         to_complement = 1;
2493         /* FALLTHROUGH */
2494 
2495     case BOUNDU:
2496       do_boundu:
2497         switch((bound_type) FLAGS(c)) {
2498             case TRADITIONAL_BOUND:
2499                 FBC_BOUND(isWORDCHAR_L1, isWORDCHAR_uni, isWORDCHAR_utf8_safe);
2500                 break;
2501             case GCB_BOUND:
2502                 if (s == reginfo->strbeg) {
2503                     if (reginfo->intuit || regtry(reginfo, &s))
2504                     {
2505                         goto got_it;
2506                     }
2507 
2508                     /* Didn't match.  Try at the next position (if there is one) */
2509                     s += (utf8_target) ? UTF8SKIP(s) : 1;
2510                     if (UNLIKELY(s >= reginfo->strend)) {
2511                         break;
2512                     }
2513                 }
2514 
2515                 if (utf8_target) {
2516                     GCB_enum before = getGCB_VAL_UTF8(
2517                                                reghop3((U8*)s, -1,
2518                                                        (U8*)(reginfo->strbeg)),
2519                                                (U8*) reginfo->strend);
2520                     while (s < strend) {
2521                         GCB_enum after = getGCB_VAL_UTF8((U8*) s,
2522                                                         (U8*) reginfo->strend);
2523                         if (   (to_complement ^ isGCB(before,
2524                                                       after,
2525                                                       (U8*) reginfo->strbeg,
2526                                                       (U8*) s,
2527                                                       utf8_target))
2528                             && (reginfo->intuit || regtry(reginfo, &s)))
2529                         {
2530                             goto got_it;
2531                         }
2532                         before = after;
2533                         s += UTF8SKIP(s);
2534                     }
2535                 }
2536                 else {  /* Not utf8.  Everything is a GCB except between CR and
2537                            LF */
2538                     while (s < strend) {
2539                         if ((to_complement ^ (   UCHARAT(s - 1) != '\r'
2540                                               || UCHARAT(s) != '\n'))
2541                             && (reginfo->intuit || regtry(reginfo, &s)))
2542                         {
2543                             goto got_it;
2544                         }
2545                         s++;
2546                     }
2547                 }
2548 
2549                 /* And, since this is a bound, it can match after the final
2550                  * character in the string */
2551                 if ((reginfo->intuit || regtry(reginfo, &s))) {
2552                     goto got_it;
2553                 }
2554                 break;
2555 
2556             case LB_BOUND:
2557                 if (s == reginfo->strbeg) {
2558                     if (reginfo->intuit || regtry(reginfo, &s)) {
2559                         goto got_it;
2560                     }
2561                     s += (utf8_target) ? UTF8SKIP(s) : 1;
2562                     if (UNLIKELY(s >= reginfo->strend)) {
2563                         break;
2564                     }
2565                 }
2566 
2567                 if (utf8_target) {
2568                     LB_enum before = getLB_VAL_UTF8(reghop3((U8*)s,
2569                                                                -1,
2570                                                                (U8*)(reginfo->strbeg)),
2571                                                        (U8*) reginfo->strend);
2572                     while (s < strend) {
2573                         LB_enum after = getLB_VAL_UTF8((U8*) s, (U8*) reginfo->strend);
2574                         if (to_complement ^ isLB(before,
2575                                                  after,
2576                                                  (U8*) reginfo->strbeg,
2577                                                  (U8*) s,
2578                                                  (U8*) reginfo->strend,
2579                                                  utf8_target)
2580                             && (reginfo->intuit || regtry(reginfo, &s)))
2581                         {
2582                             goto got_it;
2583                         }
2584                         before = after;
2585                         s += UTF8SKIP(s);
2586                     }
2587                 }
2588                 else {  /* Not utf8. */
2589                     LB_enum before = getLB_VAL_CP((U8) *(s -1));
2590                     while (s < strend) {
2591                         LB_enum after = getLB_VAL_CP((U8) *s);
2592                         if (to_complement ^ isLB(before,
2593                                                  after,
2594                                                  (U8*) reginfo->strbeg,
2595                                                  (U8*) s,
2596                                                  (U8*) reginfo->strend,
2597                                                  utf8_target)
2598                             && (reginfo->intuit || regtry(reginfo, &s)))
2599                         {
2600                             goto got_it;
2601                         }
2602                         before = after;
2603                         s++;
2604                     }
2605                 }
2606 
2607                 if (reginfo->intuit || regtry(reginfo, &s)) {
2608                     goto got_it;
2609                 }
2610 
2611                 break;
2612 
2613             case SB_BOUND:
2614                 if (s == reginfo->strbeg) {
2615                     if (reginfo->intuit || regtry(reginfo, &s)) {
2616                         goto got_it;
2617                     }
2618                     s += (utf8_target) ? UTF8SKIP(s) : 1;
2619                     if (UNLIKELY(s >= reginfo->strend)) {
2620                         break;
2621                     }
2622                 }
2623 
2624                 if (utf8_target) {
2625                     SB_enum before = getSB_VAL_UTF8(reghop3((U8*)s,
2626                                                         -1,
2627                                                         (U8*)(reginfo->strbeg)),
2628                                                       (U8*) reginfo->strend);
2629                     while (s < strend) {
2630                         SB_enum after = getSB_VAL_UTF8((U8*) s,
2631                                                          (U8*) reginfo->strend);
2632                         if ((to_complement ^ isSB(before,
2633                                                   after,
2634                                                   (U8*) reginfo->strbeg,
2635                                                   (U8*) s,
2636                                                   (U8*) reginfo->strend,
2637                                                   utf8_target))
2638                             && (reginfo->intuit || regtry(reginfo, &s)))
2639                         {
2640                             goto got_it;
2641                         }
2642                         before = after;
2643                         s += UTF8SKIP(s);
2644                     }
2645                 }
2646                 else {  /* Not utf8. */
2647                     SB_enum before = getSB_VAL_CP((U8) *(s -1));
2648                     while (s < strend) {
2649                         SB_enum after = getSB_VAL_CP((U8) *s);
2650                         if ((to_complement ^ isSB(before,
2651                                                   after,
2652                                                   (U8*) reginfo->strbeg,
2653                                                   (U8*) s,
2654                                                   (U8*) reginfo->strend,
2655                                                   utf8_target))
2656                             && (reginfo->intuit || regtry(reginfo, &s)))
2657                         {
2658                             goto got_it;
2659                         }
2660                         before = after;
2661                         s++;
2662                     }
2663                 }
2664 
2665                 /* Here are at the final position in the target string.  The SB
2666                  * value is always true here, so matches, depending on other
2667                  * constraints */
2668                 if (reginfo->intuit || regtry(reginfo, &s)) {
2669                     goto got_it;
2670                 }
2671 
2672                 break;
2673 
2674             case WB_BOUND:
2675                 if (s == reginfo->strbeg) {
2676                     if (reginfo->intuit || regtry(reginfo, &s)) {
2677                         goto got_it;
2678                     }
2679                     s += (utf8_target) ? UTF8SKIP(s) : 1;
2680                     if (UNLIKELY(s >= reginfo->strend)) {
2681                         break;
2682                     }
2683                 }
2684 
2685                 if (utf8_target) {
2686                     /* We are at a boundary between char_sub_0 and char_sub_1.
2687                      * We also keep track of the value for char_sub_-1 as we
2688                      * loop through the line.   Context may be needed to make a
2689                      * determination, and if so, this can save having to
2690                      * recalculate it */
2691                     WB_enum previous = WB_UNKNOWN;
2692                     WB_enum before = getWB_VAL_UTF8(
2693                                               reghop3((U8*)s,
2694                                                       -1,
2695                                                       (U8*)(reginfo->strbeg)),
2696                                               (U8*) reginfo->strend);
2697                     while (s < strend) {
2698                         WB_enum after = getWB_VAL_UTF8((U8*) s,
2699                                                         (U8*) reginfo->strend);
2700                         if ((to_complement ^ isWB(previous,
2701                                                   before,
2702                                                   after,
2703                                                   (U8*) reginfo->strbeg,
2704                                                   (U8*) s,
2705                                                   (U8*) reginfo->strend,
2706                                                   utf8_target))
2707                             && (reginfo->intuit || regtry(reginfo, &s)))
2708                         {
2709                             goto got_it;
2710                         }
2711                         previous = before;
2712                         before = after;
2713                         s += UTF8SKIP(s);
2714                     }
2715                 }
2716                 else {  /* Not utf8. */
2717                     WB_enum previous = WB_UNKNOWN;
2718                     WB_enum before = getWB_VAL_CP((U8) *(s -1));
2719                     while (s < strend) {
2720                         WB_enum after = getWB_VAL_CP((U8) *s);
2721                         if ((to_complement ^ isWB(previous,
2722                                                   before,
2723                                                   after,
2724                                                   (U8*) reginfo->strbeg,
2725                                                   (U8*) s,
2726                                                   (U8*) reginfo->strend,
2727                                                   utf8_target))
2728                             && (reginfo->intuit || regtry(reginfo, &s)))
2729                         {
2730                             goto got_it;
2731                         }
2732                         previous = before;
2733                         before = after;
2734                         s++;
2735                     }
2736                 }
2737 
2738                 if (reginfo->intuit || regtry(reginfo, &s)) {
2739                     goto got_it;
2740                 }
2741         }
2742         break;
2743 
2744     case LNBREAK:
2745         REXEC_FBC_CSCAN(is_LNBREAK_utf8_safe(s, strend),
2746                         is_LNBREAK_latin1_safe(s, strend)
2747         );
2748         break;
2749 
2750     case ASCII:
2751         REXEC_FBC_FIND_NEXT_SCAN(0, find_next_ascii(s, strend, utf8_target));
2752         break;
2753 
2754     case NASCII:
2755         if (utf8_target) {
2756             REXEC_FBC_FIND_NEXT_SCAN(1, find_next_non_ascii(s, strend,
2757                                                             utf8_target));
2758         }
2759         else {
2760             REXEC_FBC_FIND_NEXT_SCAN(0, find_next_non_ascii(s, strend,
2761                                                             utf8_target));
2762         }
2763 
2764         break;
2765 
2766     /* The argument to all the POSIX node types is the class number to pass to
2767      * _generic_isCC() to build a mask for searching in PL_charclass[] */
2768 
2769     case NPOSIXL:
2770         to_complement = 1;
2771         /* FALLTHROUGH */
2772 
2773     case POSIXL:
2774         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
2775         REXEC_FBC_CSCAN(to_complement ^ cBOOL(isFOO_utf8_lc(FLAGS(c), (U8 *) s, (U8 *) strend)),
2776                         to_complement ^ cBOOL(isFOO_lc(FLAGS(c), *s)));
2777         break;
2778 
2779     case NPOSIXD:
2780         to_complement = 1;
2781         /* FALLTHROUGH */
2782 
2783     case POSIXD:
2784         if (utf8_target) {
2785             goto posix_utf8;
2786         }
2787         goto posixa;
2788 
2789     case NPOSIXA:
2790         if (utf8_target) {
2791             /* The complement of something that matches only ASCII matches all
2792              * non-ASCII, plus everything in ASCII that isn't in the class. */
2793             REXEC_FBC_CLASS_SCAN(1,   ! isASCII_utf8_safe(s, strend)
2794                                    || ! _generic_isCC_A(*s, FLAGS(c)));
2795             break;
2796         }
2797 
2798         to_complement = 1;
2799         goto posixa;
2800 
2801     case POSIXA:
2802         /* Don't need to worry about utf8, as it can match only a single
2803          * byte invariant character.  But we do anyway for performance reasons,
2804          * as otherwise we would have to examine all the continuation
2805          * characters */
2806         if (utf8_target) {
2807             REXEC_FBC_CLASS_SCAN(1, _generic_isCC_A(*s, FLAGS(c)));
2808             break;
2809         }
2810 
2811       posixa:
2812         REXEC_FBC_CLASS_SCAN(0, /* 0=>not-utf8 */
2813                         to_complement ^ cBOOL(_generic_isCC_A(*s, FLAGS(c))));
2814         break;
2815 
2816     case NPOSIXU:
2817         to_complement = 1;
2818         /* FALLTHROUGH */
2819 
2820     case POSIXU:
2821         if (! utf8_target) {
2822             REXEC_FBC_CLASS_SCAN(0, /* 0=>not-utf8 */
2823                                  to_complement ^ cBOOL(_generic_isCC(*s,
2824                                                                     FLAGS(c))));
2825         }
2826         else {
2827 
2828           posix_utf8:
2829             classnum = (_char_class_number) FLAGS(c);
2830             switch (classnum) {
2831                 default:
2832                     REXEC_FBC_CLASS_SCAN(1, /* 1=>is-utf8 */
2833                         to_complement ^ cBOOL(_invlist_contains_cp(
2834                                               PL_XPosix_ptrs[classnum],
2835                                               utf8_to_uvchr_buf((U8 *) s,
2836                                                                 (U8 *) strend,
2837                                                                 NULL))));
2838                     break;
2839                 case _CC_ENUM_SPACE:
2840                     REXEC_FBC_CLASS_SCAN(1, /* 1=>is-utf8 */
2841                         to_complement ^ cBOOL(isSPACE_utf8_safe(s, strend)));
2842                     break;
2843 
2844                 case _CC_ENUM_BLANK:
2845                     REXEC_FBC_CLASS_SCAN(1,
2846                         to_complement ^ cBOOL(isBLANK_utf8_safe(s, strend)));
2847                     break;
2848 
2849                 case _CC_ENUM_XDIGIT:
2850                     REXEC_FBC_CLASS_SCAN(1,
2851                        to_complement ^ cBOOL(isXDIGIT_utf8_safe(s, strend)));
2852                     break;
2853 
2854                 case _CC_ENUM_VERTSPACE:
2855                     REXEC_FBC_CLASS_SCAN(1,
2856                        to_complement ^ cBOOL(isVERTWS_utf8_safe(s, strend)));
2857                     break;
2858 
2859                 case _CC_ENUM_CNTRL:
2860                     REXEC_FBC_CLASS_SCAN(1,
2861                         to_complement ^ cBOOL(isCNTRL_utf8_safe(s, strend)));
2862                     break;
2863             }
2864         }
2865         break;
2866 
2867     case AHOCORASICKC:
2868     case AHOCORASICK:
2869         {
2870             DECL_TRIE_TYPE(c);
2871             /* what trie are we using right now */
2872             reg_ac_data *aho = (reg_ac_data*)progi->data->data[ ARG( c ) ];
2873             reg_trie_data *trie = (reg_trie_data*)progi->data->data[ aho->trie ];
2874             HV *widecharmap = MUTABLE_HV(progi->data->data[ aho->trie + 1 ]);
2875 
2876             const char *last_start = strend - trie->minlen;
2877 #ifdef DEBUGGING
2878             const char *real_start = s;
2879 #endif
2880             STRLEN maxlen = trie->maxlen;
2881             SV *sv_points;
2882             U8 **points; /* map of where we were in the input string
2883                             when reading a given char. For ASCII this
2884                             is unnecessary overhead as the relationship
2885                             is always 1:1, but for Unicode, especially
2886                             case folded Unicode this is not true. */
2887             U8 foldbuf[ UTF8_MAXBYTES_CASE + 1 ];
2888             U8 *bitmap=NULL;
2889 
2890 
2891             GET_RE_DEBUG_FLAGS_DECL;
2892 
2893             /* We can't just allocate points here. We need to wrap it in
2894              * an SV so it gets freed properly if there is a croak while
2895              * running the match */
2896             ENTER;
2897             SAVETMPS;
2898             sv_points=newSV(maxlen * sizeof(U8 *));
2899             SvCUR_set(sv_points,
2900                 maxlen * sizeof(U8 *));
2901             SvPOK_on(sv_points);
2902             sv_2mortal(sv_points);
2903             points=(U8**)SvPV_nolen(sv_points );
2904             if ( trie_type != trie_utf8_fold
2905                  && (trie->bitmap || OP(c)==AHOCORASICKC) )
2906             {
2907                 if (trie->bitmap)
2908                     bitmap=(U8*)trie->bitmap;
2909                 else
2910                     bitmap=(U8*)ANYOF_BITMAP(c);
2911             }
2912             /* this is the Aho-Corasick algorithm modified a touch
2913                to include special handling for long "unknown char" sequences.
2914                The basic idea being that we use AC as long as we are dealing
2915                with a possible matching char, when we encounter an unknown char
2916                (and we have not encountered an accepting state) we scan forward
2917                until we find a legal starting char.
2918                AC matching is basically that of trie matching, except that when
2919                we encounter a failing transition, we fall back to the current
2920                states "fail state", and try the current char again, a process
2921                we repeat until we reach the root state, state 1, or a legal
2922                transition. If we fail on the root state then we can either
2923                terminate if we have reached an accepting state previously, or
2924                restart the entire process from the beginning if we have not.
2925 
2926              */
2927             while (s <= last_start) {
2928                 const U32 uniflags = UTF8_ALLOW_DEFAULT;
2929                 U8 *uc = (U8*)s;
2930                 U16 charid = 0;
2931                 U32 base = 1;
2932                 U32 state = 1;
2933                 UV uvc = 0;
2934                 STRLEN len = 0;
2935                 STRLEN foldlen = 0;
2936                 U8 *uscan = (U8*)NULL;
2937                 U8 *leftmost = NULL;
2938 #ifdef DEBUGGING
2939                 U32 accepted_word= 0;
2940 #endif
2941                 U32 pointpos = 0;
2942 
2943                 while ( state && uc <= (U8*)strend ) {
2944                     int failed=0;
2945                     U32 word = aho->states[ state ].wordnum;
2946 
2947                     if( state==1 ) {
2948                         if ( bitmap ) {
2949                             DEBUG_TRIE_EXECUTE_r(
2950                                 if ( uc <= (U8*)last_start && !BITMAP_TEST(bitmap,*uc) ) {
2951                                     dump_exec_pos( (char *)uc, c, strend, real_start,
2952                                         (char *)uc, utf8_target, 0 );
2953                                     Perl_re_printf( aTHX_
2954                                         " Scanning for legal start char...\n");
2955                                 }
2956                             );
2957                             if (utf8_target) {
2958                                 while ( uc <= (U8*)last_start && !BITMAP_TEST(bitmap,*uc) ) {
2959                                     uc += UTF8SKIP(uc);
2960                                 }
2961                             } else {
2962                                 while ( uc <= (U8*)last_start  && !BITMAP_TEST(bitmap,*uc) ) {
2963                                     uc++;
2964                                 }
2965                             }
2966                             s= (char *)uc;
2967                         }
2968                         if (uc >(U8*)last_start) break;
2969                     }
2970 
2971                     if ( word ) {
2972                         U8 *lpos= points[ (pointpos - trie->wordinfo[word].len) % maxlen ];
2973                         if (!leftmost || lpos < leftmost) {
2974                             DEBUG_r(accepted_word=word);
2975                             leftmost= lpos;
2976                         }
2977                         if (base==0) break;
2978 
2979                     }
2980                     points[pointpos++ % maxlen]= uc;
2981                     if (foldlen || uc < (U8*)strend) {
2982                         REXEC_TRIE_READ_CHAR(trie_type, trie, widecharmap, uc,
2983                                              (U8 *) strend, uscan, len, uvc,
2984                                              charid, foldlen, foldbuf,
2985                                              uniflags);
2986                         DEBUG_TRIE_EXECUTE_r({
2987                             dump_exec_pos( (char *)uc, c, strend,
2988                                         real_start, s, utf8_target, 0);
2989                             Perl_re_printf( aTHX_
2990                                 " Charid:%3u CP:%4" UVxf " ",
2991                                  charid, uvc);
2992                         });
2993                     }
2994                     else {
2995                         len = 0;
2996                         charid = 0;
2997                     }
2998 
2999 
3000                     do {
3001 #ifdef DEBUGGING
3002                         word = aho->states[ state ].wordnum;
3003 #endif
3004                         base = aho->states[ state ].trans.base;
3005 
3006                         DEBUG_TRIE_EXECUTE_r({
3007                             if (failed)
3008                                 dump_exec_pos( (char *)uc, c, strend, real_start,
3009                                     s,   utf8_target, 0 );
3010                             Perl_re_printf( aTHX_
3011                                 "%sState: %4" UVxf ", word=%" UVxf,
3012                                 failed ? " Fail transition to " : "",
3013                                 (UV)state, (UV)word);
3014                         });
3015                         if ( base ) {
3016                             U32 tmp;
3017                             I32 offset;
3018                             if (charid &&
3019                                  ( ((offset = base + charid
3020                                     - 1 - trie->uniquecharcount)) >= 0)
3021                                  && ((U32)offset < trie->lasttrans)
3022                                  && trie->trans[offset].check == state
3023                                  && (tmp=trie->trans[offset].next))
3024                             {
3025                                 DEBUG_TRIE_EXECUTE_r(
3026                                     Perl_re_printf( aTHX_ " - legal\n"));
3027                                 state = tmp;
3028                                 break;
3029                             }
3030                             else {
3031                                 DEBUG_TRIE_EXECUTE_r(
3032                                     Perl_re_printf( aTHX_ " - fail\n"));
3033                                 failed = 1;
3034                                 state = aho->fail[state];
3035                             }
3036                         }
3037                         else {
3038                             /* we must be accepting here */
3039                             DEBUG_TRIE_EXECUTE_r(
3040                                     Perl_re_printf( aTHX_ " - accepting\n"));
3041                             failed = 1;
3042                             break;
3043                         }
3044                     } while(state);
3045                     uc += len;
3046                     if (failed) {
3047                         if (leftmost)
3048                             break;
3049                         if (!state) state = 1;
3050                     }
3051                 }
3052                 if ( aho->states[ state ].wordnum ) {
3053                     U8 *lpos = points[ (pointpos - trie->wordinfo[aho->states[ state ].wordnum].len) % maxlen ];
3054                     if (!leftmost || lpos < leftmost) {
3055                         DEBUG_r(accepted_word=aho->states[ state ].wordnum);
3056                         leftmost = lpos;
3057                     }
3058                 }
3059                 if (leftmost) {
3060                     s = (char*)leftmost;
3061                     DEBUG_TRIE_EXECUTE_r({
3062                         Perl_re_printf( aTHX_  "Matches word #%" UVxf " at position %" IVdf ". Trying full pattern...\n",
3063                             (UV)accepted_word, (IV)(s - real_start)
3064                         );
3065                     });
3066                     if (reginfo->intuit || regtry(reginfo, &s)) {
3067                         FREETMPS;
3068                         LEAVE;
3069                         goto got_it;
3070                     }
3071                     s = HOPc(s,1);
3072                     DEBUG_TRIE_EXECUTE_r({
3073                         Perl_re_printf( aTHX_ "Pattern failed. Looking for new start point...\n");
3074                     });
3075                 } else {
3076                     DEBUG_TRIE_EXECUTE_r(
3077                         Perl_re_printf( aTHX_ "No match.\n"));
3078                     break;
3079                 }
3080             }
3081             FREETMPS;
3082             LEAVE;
3083         }
3084         break;
3085     default:
3086         Perl_croak(aTHX_ "panic: unknown regstclass %d", (int)OP(c));
3087     }
3088     return 0;
3089   got_it:
3090     return s;
3091 }
3092 
3093 /* set RX_SAVED_COPY, RX_SUBBEG etc.
3094  * flags have same meanings as with regexec_flags() */
3095 
3096 static void
3097 S_reg_set_capture_string(pTHX_ REGEXP * const rx,
3098                             char *strbeg,
3099                             char *strend,
3100                             SV *sv,
3101                             U32 flags,
3102                             bool utf8_target)
3103 {
3104     struct regexp *const prog = ReANY(rx);
3105 
3106     if (flags & REXEC_COPY_STR) {
3107 #ifdef PERL_ANY_COW
3108         if (SvCANCOW(sv)) {
3109             DEBUG_C(Perl_re_printf( aTHX_
3110                               "Copy on write: regexp capture, type %d\n",
3111                                     (int) SvTYPE(sv)));
3112             /* Create a new COW SV to share the match string and store
3113              * in saved_copy, unless the current COW SV in saved_copy
3114              * is valid and suitable for our purpose */
3115             if ((   prog->saved_copy
3116                  && SvIsCOW(prog->saved_copy)
3117                  && SvPOKp(prog->saved_copy)
3118                  && SvIsCOW(sv)
3119                  && SvPOKp(sv)
3120                  && SvPVX(sv) == SvPVX(prog->saved_copy)))
3121             {
3122                 /* just reuse saved_copy SV */
3123                 if (RXp_MATCH_COPIED(prog)) {
3124                     Safefree(prog->subbeg);
3125                     RXp_MATCH_COPIED_off(prog);
3126                 }
3127             }
3128             else {
3129                 /* create new COW SV to share string */
3130                 RXp_MATCH_COPY_FREE(prog);
3131                 prog->saved_copy = sv_setsv_cow(prog->saved_copy, sv);
3132             }
3133             prog->subbeg = (char *)SvPVX_const(prog->saved_copy);
3134             assert (SvPOKp(prog->saved_copy));
3135             prog->sublen  = strend - strbeg;
3136             prog->suboffset = 0;
3137             prog->subcoffset = 0;
3138         } else
3139 #endif
3140         {
3141             SSize_t min = 0;
3142             SSize_t max = strend - strbeg;
3143             SSize_t sublen;
3144 
3145             if (    (flags & REXEC_COPY_SKIP_POST)
3146                 && !(prog->extflags & RXf_PMf_KEEPCOPY) /* //p */
3147                 && !(PL_sawampersand & SAWAMPERSAND_RIGHT)
3148             ) { /* don't copy $' part of string */
3149                 U32 n = 0;
3150                 max = -1;
3151                 /* calculate the right-most part of the string covered
3152                  * by a capture. Due to lookahead, this may be to
3153                  * the right of $&, so we have to scan all captures */
3154                 while (n <= prog->lastparen) {
3155                     if (prog->offs[n].end > max)
3156                         max = prog->offs[n].end;
3157                     n++;
3158                 }
3159                 if (max == -1)
3160                     max = (PL_sawampersand & SAWAMPERSAND_LEFT)
3161                             ? prog->offs[0].start
3162                             : 0;
3163                 assert(max >= 0 && max <= strend - strbeg);
3164             }
3165 
3166             if (    (flags & REXEC_COPY_SKIP_PRE)
3167                 && !(prog->extflags & RXf_PMf_KEEPCOPY) /* //p */
3168                 && !(PL_sawampersand & SAWAMPERSAND_LEFT)
3169             ) { /* don't copy $` part of string */
3170                 U32 n = 0;
3171                 min = max;
3172                 /* calculate the left-most part of the string covered
3173                  * by a capture. Due to lookbehind, this may be to
3174                  * the left of $&, so we have to scan all captures */
3175                 while (min && n <= prog->lastparen) {
3176                     if (   prog->offs[n].start != -1
3177                         && prog->offs[n].start < min)
3178                     {
3179                         min = prog->offs[n].start;
3180                     }
3181                     n++;
3182                 }
3183                 if ((PL_sawampersand & SAWAMPERSAND_RIGHT)
3184                     && min >  prog->offs[0].end
3185                 )
3186                     min = prog->offs[0].end;
3187 
3188             }
3189 
3190             assert(min >= 0 && min <= max && min <= strend - strbeg);
3191             sublen = max - min;
3192 
3193             if (RXp_MATCH_COPIED(prog)) {
3194                 if (sublen > prog->sublen)
3195                     prog->subbeg =
3196                             (char*)saferealloc(prog->subbeg, sublen+1);
3197             }
3198             else
3199                 prog->subbeg = (char*)safemalloc(sublen+1);
3200             Copy(strbeg + min, prog->subbeg, sublen, char);
3201             prog->subbeg[sublen] = '\0';
3202             prog->suboffset = min;
3203             prog->sublen = sublen;
3204             RXp_MATCH_COPIED_on(prog);
3205         }
3206         prog->subcoffset = prog->suboffset;
3207         if (prog->suboffset && utf8_target) {
3208             /* Convert byte offset to chars.
3209              * XXX ideally should only compute this if @-/@+
3210              * has been seen, a la PL_sawampersand ??? */
3211 
3212             /* If there's a direct correspondence between the
3213              * string which we're matching and the original SV,
3214              * then we can use the utf8 len cache associated with
3215              * the SV. In particular, it means that under //g,
3216              * sv_pos_b2u() will use the previously cached
3217              * position to speed up working out the new length of
3218              * subcoffset, rather than counting from the start of
3219              * the string each time. This stops
3220              *   $x = "\x{100}" x 1E6; 1 while $x =~ /(.)/g;
3221              * from going quadratic */
3222             if (SvPOKp(sv) && SvPVX(sv) == strbeg)
3223                 prog->subcoffset = sv_pos_b2u_flags(sv, prog->subcoffset,
3224                                                 SV_GMAGIC|SV_CONST_RETURN);
3225             else
3226                 prog->subcoffset = utf8_length((U8*)strbeg,
3227                                     (U8*)(strbeg+prog->suboffset));
3228         }
3229     }
3230     else {
3231         RXp_MATCH_COPY_FREE(prog);
3232         prog->subbeg = strbeg;
3233         prog->suboffset = 0;
3234         prog->subcoffset = 0;
3235         prog->sublen = strend - strbeg;
3236     }
3237 }
3238 
3239 
3240 
3241 
3242 /*
3243  - regexec_flags - match a regexp against a string
3244  */
3245 I32
3246 Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, char *strend,
3247 	      char *strbeg, SSize_t minend, SV *sv, void *data, U32 flags)
3248 /* stringarg: the point in the string at which to begin matching */
3249 /* strend:    pointer to null at end of string */
3250 /* strbeg:    real beginning of string */
3251 /* minend:    end of match must be >= minend bytes after stringarg. */
3252 /* sv:        SV being matched: only used for utf8 flag, pos() etc; string
3253  *            itself is accessed via the pointers above */
3254 /* data:      May be used for some additional optimizations.
3255               Currently unused. */
3256 /* flags:     For optimizations. See REXEC_* in regexp.h */
3257 
3258 {
3259     struct regexp *const prog = ReANY(rx);
3260     char *s;
3261     regnode *c;
3262     char *startpos;
3263     SSize_t minlen;		/* must match at least this many chars */
3264     SSize_t dontbother = 0;	/* how many characters not to try at end */
3265     const bool utf8_target = cBOOL(DO_UTF8(sv));
3266     I32 multiline;
3267     RXi_GET_DECL(prog,progi);
3268     regmatch_info reginfo_buf;  /* create some info to pass to regtry etc */
3269     regmatch_info *const reginfo = &reginfo_buf;
3270     regexp_paren_pair *swap = NULL;
3271     I32 oldsave;
3272     GET_RE_DEBUG_FLAGS_DECL;
3273 
3274     PERL_ARGS_ASSERT_REGEXEC_FLAGS;
3275     PERL_UNUSED_ARG(data);
3276 
3277     /* Be paranoid... */
3278     if (prog == NULL) {
3279 	Perl_croak(aTHX_ "NULL regexp parameter");
3280     }
3281 
3282     DEBUG_EXECUTE_r(
3283         debug_start_match(rx, utf8_target, stringarg, strend,
3284         "Matching");
3285     );
3286 
3287     startpos = stringarg;
3288 
3289     /* set these early as they may be used by the HOP macros below */
3290     reginfo->strbeg = strbeg;
3291     reginfo->strend = strend;
3292     reginfo->is_utf8_target = cBOOL(utf8_target);
3293 
3294     if (prog->intflags & PREGf_GPOS_SEEN) {
3295         MAGIC *mg;
3296 
3297         /* set reginfo->ganch, the position where \G can match */
3298 
3299         reginfo->ganch =
3300             (flags & REXEC_IGNOREPOS)
3301             ? stringarg /* use start pos rather than pos() */
3302             : ((mg = mg_find_mglob(sv)) && mg->mg_len >= 0)
3303               /* Defined pos(): */
3304             ? strbeg + MgBYTEPOS(mg, sv, strbeg, strend-strbeg)
3305             : strbeg; /* pos() not defined; use start of string */
3306 
3307         DEBUG_GPOS_r(Perl_re_printf( aTHX_
3308             "GPOS ganch set to strbeg[%" IVdf "]\n", (IV)(reginfo->ganch - strbeg)));
3309 
3310         /* in the presence of \G, we may need to start looking earlier in
3311          * the string than the suggested start point of stringarg:
3312          * if prog->gofs is set, then that's a known, fixed minimum
3313          * offset, such as
3314          * /..\G/:   gofs = 2
3315          * /ab|c\G/: gofs = 1
3316          * or if the minimum offset isn't known, then we have to go back
3317          * to the start of the string, e.g. /w+\G/
3318          */
3319 
3320         if (prog->intflags & PREGf_ANCH_GPOS) {
3321             if (prog->gofs) {
3322                 startpos = HOPBACKc(reginfo->ganch, prog->gofs);
3323                 if (!startpos ||
3324                     ((flags & REXEC_FAIL_ON_UNDERFLOW) && startpos < stringarg))
3325                 {
3326                     DEBUG_r(Perl_re_printf( aTHX_
3327                             "fail: ganch-gofs before earliest possible start\n"));
3328                     return 0;
3329                 }
3330             }
3331             else
3332                 startpos = reginfo->ganch;
3333         }
3334         else if (prog->gofs) {
3335             startpos = HOPBACKc(startpos, prog->gofs);
3336             if (!startpos)
3337                 startpos = strbeg;
3338         }
3339         else if (prog->intflags & PREGf_GPOS_FLOAT)
3340             startpos = strbeg;
3341     }
3342 
3343     minlen = prog->minlen;
3344     if ((startpos + minlen) > strend || startpos < strbeg) {
3345         DEBUG_r(Perl_re_printf( aTHX_
3346                     "Regex match can't succeed, so not even tried\n"));
3347         return 0;
3348     }
3349 
3350     /* at the end of this function, we'll do a LEAVE_SCOPE(oldsave),
3351      * which will call destuctors to reset PL_regmatch_state, free higher
3352      * PL_regmatch_slabs, and clean up regmatch_info_aux and
3353      * regmatch_info_aux_eval */
3354 
3355     oldsave = PL_savestack_ix;
3356 
3357     s = startpos;
3358 
3359     if ((prog->extflags & RXf_USE_INTUIT)
3360         && !(flags & REXEC_CHECKED))
3361     {
3362 	s = re_intuit_start(rx, sv, strbeg, startpos, strend,
3363                                     flags, NULL);
3364 	if (!s)
3365 	    return 0;
3366 
3367 	if (prog->extflags & RXf_CHECK_ALL) {
3368             /* we can match based purely on the result of INTUIT.
3369              * Set up captures etc just for $& and $-[0]
3370              * (an intuit-only match wont have $1,$2,..) */
3371             assert(!prog->nparens);
3372 
3373             /* s/// doesn't like it if $& is earlier than where we asked it to
3374              * start searching (which can happen on something like /.\G/) */
3375             if (       (flags & REXEC_FAIL_ON_UNDERFLOW)
3376                     && (s < stringarg))
3377             {
3378                 /* this should only be possible under \G */
3379                 assert(prog->intflags & PREGf_GPOS_SEEN);
3380                 DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
3381                     "matched, but failing for REXEC_FAIL_ON_UNDERFLOW\n"));
3382                 goto phooey;
3383             }
3384 
3385             /* match via INTUIT shouldn't have any captures.
3386              * Let @-, @+, $^N know */
3387             prog->lastparen = prog->lastcloseparen = 0;
3388             RXp_MATCH_UTF8_set(prog, utf8_target);
3389             prog->offs[0].start = s - strbeg;
3390             prog->offs[0].end = utf8_target
3391                 ? (char*)utf8_hop((U8*)s, prog->minlenret) - strbeg
3392                 : s - strbeg + prog->minlenret;
3393             if ( !(flags & REXEC_NOT_FIRST) )
3394                 S_reg_set_capture_string(aTHX_ rx,
3395                                         strbeg, strend,
3396                                         sv, flags, utf8_target);
3397 
3398 	    return 1;
3399         }
3400     }
3401 
3402     multiline = prog->extflags & RXf_PMf_MULTILINE;
3403 
3404     if (strend - s < (minlen+(prog->check_offset_min<0?prog->check_offset_min:0))) {
3405         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
3406 			      "String too short [regexec_flags]...\n"));
3407 	goto phooey;
3408     }
3409 
3410     /* Check validity of program. */
3411     if (UCHARAT(progi->program) != REG_MAGIC) {
3412 	Perl_croak(aTHX_ "corrupted regexp program");
3413     }
3414 
3415     RXp_MATCH_TAINTED_off(prog);
3416     RXp_MATCH_UTF8_set(prog, utf8_target);
3417 
3418     reginfo->prog = rx;	 /* Yes, sorry that this is confusing.  */
3419     reginfo->intuit = 0;
3420     reginfo->is_utf8_pat = cBOOL(RX_UTF8(rx));
3421     reginfo->warned = FALSE;
3422     reginfo->sv = sv;
3423     reginfo->poscache_maxiter = 0; /* not yet started a countdown */
3424     /* see how far we have to get to not match where we matched before */
3425     reginfo->till = stringarg + minend;
3426 
3427     if (prog->extflags & RXf_EVAL_SEEN && SvPADTMP(sv)) {
3428         /* SAVEFREESV, not sv_mortalcopy, as this SV must last until after
3429            S_cleanup_regmatch_info_aux has executed (registered by
3430            SAVEDESTRUCTOR_X below).  S_cleanup_regmatch_info_aux modifies
3431            magic belonging to this SV.
3432            Not newSVsv, either, as it does not COW.
3433         */
3434         reginfo->sv = newSV(0);
3435         SvSetSV_nosteal(reginfo->sv, sv);
3436         SAVEFREESV(reginfo->sv);
3437     }
3438 
3439     /* reserve next 2 or 3 slots in PL_regmatch_state:
3440      * slot N+0: may currently be in use: skip it
3441      * slot N+1: use for regmatch_info_aux struct
3442      * slot N+2: use for regmatch_info_aux_eval struct if we have (?{})'s
3443      * slot N+3: ready for use by regmatch()
3444      */
3445 
3446     {
3447         regmatch_state *old_regmatch_state;
3448         regmatch_slab  *old_regmatch_slab;
3449         int i, max = (prog->extflags & RXf_EVAL_SEEN) ? 2 : 1;
3450 
3451         /* on first ever match, allocate first slab */
3452         if (!PL_regmatch_slab) {
3453             Newx(PL_regmatch_slab, 1, regmatch_slab);
3454             PL_regmatch_slab->prev = NULL;
3455             PL_regmatch_slab->next = NULL;
3456             PL_regmatch_state = SLAB_FIRST(PL_regmatch_slab);
3457         }
3458 
3459         old_regmatch_state = PL_regmatch_state;
3460         old_regmatch_slab  = PL_regmatch_slab;
3461 
3462         for (i=0; i <= max; i++) {
3463             if (i == 1)
3464                 reginfo->info_aux = &(PL_regmatch_state->u.info_aux);
3465             else if (i ==2)
3466                 reginfo->info_aux_eval =
3467                 reginfo->info_aux->info_aux_eval =
3468                             &(PL_regmatch_state->u.info_aux_eval);
3469 
3470             if (++PL_regmatch_state >  SLAB_LAST(PL_regmatch_slab))
3471                 PL_regmatch_state = S_push_slab(aTHX);
3472         }
3473 
3474         /* note initial PL_regmatch_state position; at end of match we'll
3475          * pop back to there and free any higher slabs */
3476 
3477         reginfo->info_aux->old_regmatch_state = old_regmatch_state;
3478         reginfo->info_aux->old_regmatch_slab  = old_regmatch_slab;
3479         reginfo->info_aux->poscache = NULL;
3480 
3481         SAVEDESTRUCTOR_X(S_cleanup_regmatch_info_aux, reginfo->info_aux);
3482 
3483         if ((prog->extflags & RXf_EVAL_SEEN))
3484             S_setup_eval_state(aTHX_ reginfo);
3485         else
3486             reginfo->info_aux_eval = reginfo->info_aux->info_aux_eval = NULL;
3487     }
3488 
3489     /* If there is a "must appear" string, look for it. */
3490 
3491     if (PL_curpm && (PM_GETRE(PL_curpm) == rx)) {
3492         /* We have to be careful. If the previous successful match
3493            was from this regex we don't want a subsequent partially
3494            successful match to clobber the old results.
3495            So when we detect this possibility we add a swap buffer
3496            to the re, and switch the buffer each match. If we fail,
3497            we switch it back; otherwise we leave it swapped.
3498         */
3499         swap = prog->offs;
3500         /* do we need a save destructor here for eval dies? */
3501         Newxz(prog->offs, (prog->nparens + 1), regexp_paren_pair);
3502         DEBUG_BUFFERS_r(Perl_re_exec_indentf( aTHX_
3503 	    "rex=0x%" UVxf " saving  offs: orig=0x%" UVxf " new=0x%" UVxf "\n",
3504 	    0,
3505             PTR2UV(prog),
3506 	    PTR2UV(swap),
3507 	    PTR2UV(prog->offs)
3508 	));
3509     }
3510 
3511     if (prog->recurse_locinput)
3512         Zero(prog->recurse_locinput,prog->nparens + 1, char *);
3513 
3514     /* Simplest case: anchored match need be tried only once, or with
3515      * MBOL, only at the beginning of each line.
3516      *
3517      * Note that /.*.../ sets PREGf_IMPLICIT|MBOL, while /.*.../s sets
3518      * PREGf_IMPLICIT|SBOL. The idea is that with /.*.../s, if it doesn't
3519      * match at the start of the string then it won't match anywhere else
3520      * either; while with /.*.../, if it doesn't match at the beginning,
3521      * the earliest it could match is at the start of the next line */
3522 
3523     if (prog->intflags & (PREGf_ANCH & ~PREGf_ANCH_GPOS)) {
3524         char *end;
3525 
3526 	if (regtry(reginfo, &s))
3527 	    goto got_it;
3528 
3529         if (!(prog->intflags & PREGf_ANCH_MBOL))
3530             goto phooey;
3531 
3532         /* didn't match at start, try at other newline positions */
3533 
3534         if (minlen)
3535             dontbother = minlen - 1;
3536         end = HOP3c(strend, -dontbother, strbeg) - 1;
3537 
3538         /* skip to next newline */
3539 
3540         while (s <= end) { /* note it could be possible to match at the end of the string */
3541             /* NB: newlines are the same in unicode as they are in latin */
3542             if (*s++ != '\n')
3543                 continue;
3544             if (prog->check_substr || prog->check_utf8) {
3545             /* note that with PREGf_IMPLICIT, intuit can only fail
3546              * or return the start position, so it's of limited utility.
3547              * Nevertheless, I made the decision that the potential for
3548              * quick fail was still worth it - DAPM */
3549                 s = re_intuit_start(rx, sv, strbeg, s, strend, flags, NULL);
3550                 if (!s)
3551                     goto phooey;
3552             }
3553             if (regtry(reginfo, &s))
3554                 goto got_it;
3555         }
3556         goto phooey;
3557     } /* end anchored search */
3558 
3559     if (prog->intflags & PREGf_ANCH_GPOS)
3560     {
3561         /* PREGf_ANCH_GPOS should never be true if PREGf_GPOS_SEEN is not true */
3562         assert(prog->intflags & PREGf_GPOS_SEEN);
3563         /* For anchored \G, the only position it can match from is
3564          * (ganch-gofs); we already set startpos to this above; if intuit
3565          * moved us on from there, we can't possibly succeed */
3566         assert(startpos == HOPBACKc(reginfo->ganch, prog->gofs));
3567 	if (s == startpos && regtry(reginfo, &s))
3568 	    goto got_it;
3569 	goto phooey;
3570     }
3571 
3572     /* Messy cases:  unanchored match. */
3573     if ((prog->anchored_substr || prog->anchored_utf8) && prog->intflags & PREGf_SKIP) {
3574 	/* we have /x+whatever/ */
3575 	/* it must be a one character string (XXXX Except is_utf8_pat?) */
3576 	char ch;
3577 #ifdef DEBUGGING
3578 	int did_match = 0;
3579 #endif
3580 	if (utf8_target) {
3581             if (! prog->anchored_utf8) {
3582                 to_utf8_substr(prog);
3583             }
3584             ch = SvPVX_const(prog->anchored_utf8)[0];
3585 	    REXEC_FBC_SCAN(0,   /* 0=>not-utf8 */
3586 		if (*s == ch) {
3587 		    DEBUG_EXECUTE_r( did_match = 1 );
3588 		    if (regtry(reginfo, &s)) goto got_it;
3589 		    s += UTF8SKIP(s);
3590 		    while (s < strend && *s == ch)
3591 			s += UTF8SKIP(s);
3592 		}
3593 	    );
3594 
3595 	}
3596 	else {
3597             if (! prog->anchored_substr) {
3598                 if (! to_byte_substr(prog)) {
3599                     NON_UTF8_TARGET_BUT_UTF8_REQUIRED(phooey);
3600                 }
3601             }
3602             ch = SvPVX_const(prog->anchored_substr)[0];
3603 	    REXEC_FBC_SCAN(0,   /* 0=>not-utf8 */
3604 		if (*s == ch) {
3605 		    DEBUG_EXECUTE_r( did_match = 1 );
3606 		    if (regtry(reginfo, &s)) goto got_it;
3607 		    s++;
3608 		    while (s < strend && *s == ch)
3609 			s++;
3610 		}
3611 	    );
3612 	}
3613 	DEBUG_EXECUTE_r(if (!did_match)
3614                 Perl_re_printf( aTHX_
3615                                   "Did not find anchored character...\n")
3616                );
3617     }
3618     else if (prog->anchored_substr != NULL
3619 	      || prog->anchored_utf8 != NULL
3620 	      || ((prog->float_substr != NULL || prog->float_utf8 != NULL)
3621 		  && prog->float_max_offset < strend - s)) {
3622 	SV *must;
3623 	SSize_t back_max;
3624 	SSize_t back_min;
3625 	char *last;
3626 	char *last1;		/* Last position checked before */
3627 #ifdef DEBUGGING
3628 	int did_match = 0;
3629 #endif
3630 	if (prog->anchored_substr || prog->anchored_utf8) {
3631 	    if (utf8_target) {
3632                 if (! prog->anchored_utf8) {
3633                     to_utf8_substr(prog);
3634                 }
3635                 must = prog->anchored_utf8;
3636             }
3637             else {
3638                 if (! prog->anchored_substr) {
3639                     if (! to_byte_substr(prog)) {
3640                         NON_UTF8_TARGET_BUT_UTF8_REQUIRED(phooey);
3641                     }
3642                 }
3643                 must = prog->anchored_substr;
3644             }
3645 	    back_max = back_min = prog->anchored_offset;
3646 	} else {
3647 	    if (utf8_target) {
3648                 if (! prog->float_utf8) {
3649                     to_utf8_substr(prog);
3650                 }
3651                 must = prog->float_utf8;
3652             }
3653             else {
3654                 if (! prog->float_substr) {
3655                     if (! to_byte_substr(prog)) {
3656                         NON_UTF8_TARGET_BUT_UTF8_REQUIRED(phooey);
3657                     }
3658                 }
3659                 must = prog->float_substr;
3660             }
3661 	    back_max = prog->float_max_offset;
3662 	    back_min = prog->float_min_offset;
3663 	}
3664 
3665         if (back_min<0) {
3666 	    last = strend;
3667 	} else {
3668             last = HOP3c(strend,	/* Cannot start after this */
3669         	  -(SSize_t)(CHR_SVLEN(must)
3670         		 - (SvTAIL(must) != 0) + back_min), strbeg);
3671         }
3672 	if (s > reginfo->strbeg)
3673 	    last1 = HOPc(s, -1);
3674 	else
3675 	    last1 = s - 1;	/* bogus */
3676 
3677 	/* XXXX check_substr already used to find "s", can optimize if
3678 	   check_substr==must. */
3679 	dontbother = 0;
3680 	strend = HOPc(strend, -dontbother);
3681 	while ( (s <= last) &&
3682 		(s = fbm_instr((unsigned char*)HOP4c(s, back_min, strbeg,  strend),
3683 				  (unsigned char*)strend, must,
3684 				  multiline ? FBMrf_MULTILINE : 0)) ) {
3685 	    DEBUG_EXECUTE_r( did_match = 1 );
3686 	    if (HOPc(s, -back_max) > last1) {
3687 		last1 = HOPc(s, -back_min);
3688 		s = HOPc(s, -back_max);
3689 	    }
3690 	    else {
3691 		char * const t = (last1 >= reginfo->strbeg)
3692                                     ? HOPc(last1, 1) : last1 + 1;
3693 
3694 		last1 = HOPc(s, -back_min);
3695 		s = t;
3696 	    }
3697 	    if (utf8_target) {
3698 		while (s <= last1) {
3699 		    if (regtry(reginfo, &s))
3700 			goto got_it;
3701                     if (s >= last1) {
3702                         s++; /* to break out of outer loop */
3703                         break;
3704                     }
3705                     s += UTF8SKIP(s);
3706 		}
3707 	    }
3708 	    else {
3709 		while (s <= last1) {
3710 		    if (regtry(reginfo, &s))
3711 			goto got_it;
3712 		    s++;
3713 		}
3714 	    }
3715 	}
3716 	DEBUG_EXECUTE_r(if (!did_match) {
3717             RE_PV_QUOTED_DECL(quoted, utf8_target, PERL_DEBUG_PAD_ZERO(0),
3718                 SvPVX_const(must), RE_SV_DUMPLEN(must), 30);
3719             Perl_re_printf( aTHX_  "Did not find %s substr %s%s...\n",
3720 			      ((must == prog->anchored_substr || must == prog->anchored_utf8)
3721 			       ? "anchored" : "floating"),
3722                 quoted, RE_SV_TAIL(must));
3723         });
3724 	goto phooey;
3725     }
3726     else if ( (c = progi->regstclass) ) {
3727 	if (minlen) {
3728 	    const OPCODE op = OP(progi->regstclass);
3729 	    /* don't bother with what can't match */
3730 	    if (PL_regkind[op] != EXACT && PL_regkind[op] != TRIE)
3731 	        strend = HOPc(strend, -(minlen - 1));
3732 	}
3733 	DEBUG_EXECUTE_r({
3734 	    SV * const prop = sv_newmortal();
3735             regprop(prog, prop, c, reginfo, NULL);
3736 	    {
3737 		RE_PV_QUOTED_DECL(quoted,utf8_target,PERL_DEBUG_PAD_ZERO(1),
3738 		    s,strend-s,PL_dump_re_max_len);
3739                 Perl_re_printf( aTHX_
3740 		    "Matching stclass %.*s against %s (%d bytes)\n",
3741 		    (int)SvCUR(prop), SvPVX_const(prop),
3742 		     quoted, (int)(strend - s));
3743 	    }
3744 	});
3745         if (find_byclass(prog, c, s, strend, reginfo))
3746 	    goto got_it;
3747         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_  "Contradicts stclass... [regexec_flags]\n"));
3748     }
3749     else {
3750 	dontbother = 0;
3751 	if (prog->float_substr != NULL || prog->float_utf8 != NULL) {
3752 	    /* Trim the end. */
3753 	    char *last= NULL;
3754 	    SV* float_real;
3755 	    STRLEN len;
3756 	    const char *little;
3757 
3758 	    if (utf8_target) {
3759                 if (! prog->float_utf8) {
3760                     to_utf8_substr(prog);
3761                 }
3762                 float_real = prog->float_utf8;
3763             }
3764             else {
3765                 if (! prog->float_substr) {
3766                     if (! to_byte_substr(prog)) {
3767                         NON_UTF8_TARGET_BUT_UTF8_REQUIRED(phooey);
3768                     }
3769                 }
3770                 float_real = prog->float_substr;
3771             }
3772 
3773             little = SvPV_const(float_real, len);
3774 	    if (SvTAIL(float_real)) {
3775                     /* This means that float_real contains an artificial \n on
3776                      * the end due to the presence of something like this:
3777                      * /foo$/ where we can match both "foo" and "foo\n" at the
3778                      * end of the string.  So we have to compare the end of the
3779                      * string first against the float_real without the \n and
3780                      * then against the full float_real with the string.  We
3781                      * have to watch out for cases where the string might be
3782                      * smaller than the float_real or the float_real without
3783                      * the \n. */
3784 		    char *checkpos= strend - len;
3785 		    DEBUG_OPTIMISE_r(
3786                         Perl_re_printf( aTHX_
3787 			    "%sChecking for float_real.%s\n",
3788 			    PL_colors[4], PL_colors[5]));
3789 		    if (checkpos + 1 < strbeg) {
3790                         /* can't match, even if we remove the trailing \n
3791                          * string is too short to match */
3792 			DEBUG_EXECUTE_r(
3793                             Perl_re_printf( aTHX_
3794 				"%sString shorter than required trailing substring, cannot match.%s\n",
3795 				PL_colors[4], PL_colors[5]));
3796 			goto phooey;
3797 		    } else if (memEQ(checkpos + 1, little, len - 1)) {
3798                         /* can match, the end of the string matches without the
3799                          * "\n" */
3800 			last = checkpos + 1;
3801 		    } else if (checkpos < strbeg) {
3802                         /* cant match, string is too short when the "\n" is
3803                          * included */
3804 			DEBUG_EXECUTE_r(
3805                             Perl_re_printf( aTHX_
3806 				"%sString does not contain required trailing substring, cannot match.%s\n",
3807 				PL_colors[4], PL_colors[5]));
3808 			goto phooey;
3809 		    } else if (!multiline) {
3810                         /* non multiline match, so compare with the "\n" at the
3811                          * end of the string */
3812 			if (memEQ(checkpos, little, len)) {
3813 			    last= checkpos;
3814 			} else {
3815 			    DEBUG_EXECUTE_r(
3816                                 Perl_re_printf( aTHX_
3817 				    "%sString does not contain required trailing substring, cannot match.%s\n",
3818 				    PL_colors[4], PL_colors[5]));
3819 			    goto phooey;
3820 			}
3821 		    } else {
3822                         /* multiline match, so we have to search for a place
3823                          * where the full string is located */
3824 			goto find_last;
3825 		    }
3826 	    } else {
3827 		  find_last:
3828 		    if (len)
3829 			last = rninstr(s, strend, little, little + len);
3830 		    else
3831 			last = strend;	/* matching "$" */
3832 	    }
3833 	    if (!last) {
3834                 /* at one point this block contained a comment which was
3835                  * probably incorrect, which said that this was a "should not
3836                  * happen" case.  Even if it was true when it was written I am
3837                  * pretty sure it is not anymore, so I have removed the comment
3838                  * and replaced it with this one. Yves */
3839 		DEBUG_EXECUTE_r(
3840                     Perl_re_printf( aTHX_
3841 			"%sString does not contain required substring, cannot match.%s\n",
3842                         PL_colors[4], PL_colors[5]
3843 	            ));
3844 		goto phooey;
3845 	    }
3846 	    dontbother = strend - last + prog->float_min_offset;
3847 	}
3848 	if (minlen && (dontbother < minlen))
3849 	    dontbother = minlen - 1;
3850 	strend -= dontbother; 		   /* this one's always in bytes! */
3851 	/* We don't know much -- general case. */
3852 	if (utf8_target) {
3853 	    for (;;) {
3854 		if (regtry(reginfo, &s))
3855 		    goto got_it;
3856 		if (s >= strend)
3857 		    break;
3858 		s += UTF8SKIP(s);
3859 	    };
3860 	}
3861 	else {
3862 	    do {
3863 		if (regtry(reginfo, &s))
3864 		    goto got_it;
3865 	    } while (s++ < strend);
3866 	}
3867     }
3868 
3869     /* Failure. */
3870     goto phooey;
3871 
3872   got_it:
3873     /* s/// doesn't like it if $& is earlier than where we asked it to
3874      * start searching (which can happen on something like /.\G/) */
3875     if (       (flags & REXEC_FAIL_ON_UNDERFLOW)
3876             && (prog->offs[0].start < stringarg - strbeg))
3877     {
3878         /* this should only be possible under \G */
3879         assert(prog->intflags & PREGf_GPOS_SEEN);
3880         DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
3881             "matched, but failing for REXEC_FAIL_ON_UNDERFLOW\n"));
3882         goto phooey;
3883     }
3884 
3885     DEBUG_BUFFERS_r(
3886 	if (swap)
3887             Perl_re_exec_indentf( aTHX_
3888 		"rex=0x%" UVxf " freeing offs: 0x%" UVxf "\n",
3889 		0,
3890                 PTR2UV(prog),
3891 		PTR2UV(swap)
3892 	    );
3893     );
3894     Safefree(swap);
3895 
3896     /* clean up; this will trigger destructors that will free all slabs
3897      * above the current one, and cleanup the regmatch_info_aux
3898      * and regmatch_info_aux_eval sructs */
3899 
3900     LEAVE_SCOPE(oldsave);
3901 
3902     if (RXp_PAREN_NAMES(prog))
3903         (void)hv_iterinit(RXp_PAREN_NAMES(prog));
3904 
3905     /* make sure $`, $&, $', and $digit will work later */
3906     if ( !(flags & REXEC_NOT_FIRST) )
3907         S_reg_set_capture_string(aTHX_ rx,
3908                                     strbeg, reginfo->strend,
3909                                     sv, flags, utf8_target);
3910 
3911     return 1;
3912 
3913   phooey:
3914     DEBUG_EXECUTE_r(Perl_re_printf( aTHX_  "%sMatch failed%s\n",
3915 			  PL_colors[4], PL_colors[5]));
3916 
3917     /* clean up; this will trigger destructors that will free all slabs
3918      * above the current one, and cleanup the regmatch_info_aux
3919      * and regmatch_info_aux_eval sructs */
3920 
3921     LEAVE_SCOPE(oldsave);
3922 
3923     if (swap) {
3924         /* we failed :-( roll it back */
3925         DEBUG_BUFFERS_r(Perl_re_exec_indentf( aTHX_
3926 	    "rex=0x%" UVxf " rolling back offs: freeing=0x%" UVxf " restoring=0x%" UVxf "\n",
3927 	    0,
3928             PTR2UV(prog),
3929 	    PTR2UV(prog->offs),
3930 	    PTR2UV(swap)
3931 	));
3932         Safefree(prog->offs);
3933         prog->offs = swap;
3934     }
3935     return 0;
3936 }
3937 
3938 
3939 /* Set which rex is pointed to by PL_reg_curpm, handling ref counting.
3940  * Do inc before dec, in case old and new rex are the same */
3941 #define SET_reg_curpm(Re2)                          \
3942     if (reginfo->info_aux_eval) {                   \
3943 	(void)ReREFCNT_inc(Re2);		    \
3944 	ReREFCNT_dec(PM_GETRE(PL_reg_curpm));	    \
3945 	PM_SETRE((PL_reg_curpm), (Re2));	    \
3946     }
3947 
3948 
3949 /*
3950  - regtry - try match at specific point
3951  */
3952 STATIC bool			/* 0 failure, 1 success */
3953 S_regtry(pTHX_ regmatch_info *reginfo, char **startposp)
3954 {
3955     CHECKPOINT lastcp;
3956     REGEXP *const rx = reginfo->prog;
3957     regexp *const prog = ReANY(rx);
3958     SSize_t result;
3959 #ifdef DEBUGGING
3960     U32 depth = 0; /* used by REGCP_SET */
3961 #endif
3962     RXi_GET_DECL(prog,progi);
3963     GET_RE_DEBUG_FLAGS_DECL;
3964 
3965     PERL_ARGS_ASSERT_REGTRY;
3966 
3967     reginfo->cutpoint=NULL;
3968 
3969     prog->offs[0].start = *startposp - reginfo->strbeg;
3970     prog->lastparen = 0;
3971     prog->lastcloseparen = 0;
3972 
3973     /* XXXX What this code is doing here?!!!  There should be no need
3974        to do this again and again, prog->lastparen should take care of
3975        this!  --ilya*/
3976 
3977     /* Tests pat.t#187 and split.t#{13,14} seem to depend on this code.
3978      * Actually, the code in regcppop() (which Ilya may be meaning by
3979      * prog->lastparen), is not needed at all by the test suite
3980      * (op/regexp, op/pat, op/split), but that code is needed otherwise
3981      * this erroneously leaves $1 defined: "1" =~ /^(?:(\d)x)?\d$/
3982      * Meanwhile, this code *is* needed for the
3983      * above-mentioned test suite tests to succeed.  The common theme
3984      * on those tests seems to be returning null fields from matches.
3985      * --jhi updated by dapm */
3986 
3987     /* After encountering a variant of the issue mentioned above I think
3988      * the point Ilya was making is that if we properly unwind whenever
3989      * we set lastparen to a smaller value then we should not need to do
3990      * this every time, only when needed. So if we have tests that fail if
3991      * we remove this, then it suggests somewhere else we are improperly
3992      * unwinding the lastparen/paren buffers. See UNWIND_PARENS() and
3993      * places it is called, and related regcp() routines. - Yves */
3994 #if 1
3995     if (prog->nparens) {
3996 	regexp_paren_pair *pp = prog->offs;
3997 	I32 i;
3998 	for (i = prog->nparens; i > (I32)prog->lastparen; i--) {
3999 	    ++pp;
4000 	    pp->start = -1;
4001 	    pp->end = -1;
4002 	}
4003     }
4004 #endif
4005     REGCP_SET(lastcp);
4006     result = regmatch(reginfo, *startposp, progi->program + 1);
4007     if (result != -1) {
4008 	prog->offs[0].end = result;
4009 	return 1;
4010     }
4011     if (reginfo->cutpoint)
4012         *startposp= reginfo->cutpoint;
4013     REGCP_UNWIND(lastcp);
4014     return 0;
4015 }
4016 
4017 
4018 #define sayYES goto yes
4019 #define sayNO goto no
4020 #define sayNO_SILENT goto no_silent
4021 
4022 /* we dont use STMT_START/END here because it leads to
4023    "unreachable code" warnings, which are bogus, but distracting. */
4024 #define CACHEsayNO \
4025     if (ST.cache_mask) \
4026        reginfo->info_aux->poscache[ST.cache_offset] |= ST.cache_mask; \
4027     sayNO
4028 
4029 /* this is used to determine how far from the left messages like
4030    'failed...' are printed in regexec.c. It should be set such that
4031    messages are inline with the regop output that created them.
4032 */
4033 #define REPORT_CODE_OFF 29
4034 #define INDENT_CHARS(depth) ((int)(depth) % 20)
4035 #ifdef DEBUGGING
4036 int
4037 Perl_re_exec_indentf(pTHX_ const char *fmt, U32 depth, ...)
4038 {
4039     va_list ap;
4040     int result;
4041     PerlIO *f= Perl_debug_log;
4042     PERL_ARGS_ASSERT_RE_EXEC_INDENTF;
4043     va_start(ap, depth);
4044     PerlIO_printf(f, "%*s|%4" UVuf "| %*s", REPORT_CODE_OFF, "", (UV)depth, INDENT_CHARS(depth), "" );
4045     result = PerlIO_vprintf(f, fmt, ap);
4046     va_end(ap);
4047     return result;
4048 }
4049 #endif /* DEBUGGING */
4050 
4051 
4052 #define CHRTEST_UNINIT -1001 /* c1/c2 haven't been calculated yet */
4053 #define CHRTEST_VOID   -1000 /* the c1/c2 "next char" test should be skipped */
4054 #define CHRTEST_NOT_A_CP_1 -999
4055 #define CHRTEST_NOT_A_CP_2 -998
4056 
4057 /* grab a new slab and return the first slot in it */
4058 
4059 STATIC regmatch_state *
4060 S_push_slab(pTHX)
4061 {
4062     regmatch_slab *s = PL_regmatch_slab->next;
4063     if (!s) {
4064 	Newx(s, 1, regmatch_slab);
4065 	s->prev = PL_regmatch_slab;
4066 	s->next = NULL;
4067 	PL_regmatch_slab->next = s;
4068     }
4069     PL_regmatch_slab = s;
4070     return SLAB_FIRST(s);
4071 }
4072 
4073 
4074 /* push a new state then goto it */
4075 
4076 #define PUSH_STATE_GOTO(state, node, input) \
4077     pushinput = input; \
4078     scan = node; \
4079     st->resume_state = state; \
4080     goto push_state;
4081 
4082 /* push a new state with success backtracking, then goto it */
4083 
4084 #define PUSH_YES_STATE_GOTO(state, node, input) \
4085     pushinput = input; \
4086     scan = node; \
4087     st->resume_state = state; \
4088     goto push_yes_state;
4089 
4090 
4091 
4092 
4093 /*
4094 
4095 regmatch() - main matching routine
4096 
4097 This is basically one big switch statement in a loop. We execute an op,
4098 set 'next' to point the next op, and continue. If we come to a point which
4099 we may need to backtrack to on failure such as (A|B|C), we push a
4100 backtrack state onto the backtrack stack. On failure, we pop the top
4101 state, and re-enter the loop at the state indicated. If there are no more
4102 states to pop, we return failure.
4103 
4104 Sometimes we also need to backtrack on success; for example /A+/, where
4105 after successfully matching one A, we need to go back and try to
4106 match another one; similarly for lookahead assertions: if the assertion
4107 completes successfully, we backtrack to the state just before the assertion
4108 and then carry on.  In these cases, the pushed state is marked as
4109 'backtrack on success too'. This marking is in fact done by a chain of
4110 pointers, each pointing to the previous 'yes' state. On success, we pop to
4111 the nearest yes state, discarding any intermediate failure-only states.
4112 Sometimes a yes state is pushed just to force some cleanup code to be
4113 called at the end of a successful match or submatch; e.g. (??{$re}) uses
4114 it to free the inner regex.
4115 
4116 Note that failure backtracking rewinds the cursor position, while
4117 success backtracking leaves it alone.
4118 
4119 A pattern is complete when the END op is executed, while a subpattern
4120 such as (?=foo) is complete when the SUCCESS op is executed. Both of these
4121 ops trigger the "pop to last yes state if any, otherwise return true"
4122 behaviour.
4123 
4124 A common convention in this function is to use A and B to refer to the two
4125 subpatterns (or to the first nodes thereof) in patterns like /A*B/: so A is
4126 the subpattern to be matched possibly multiple times, while B is the entire
4127 rest of the pattern. Variable and state names reflect this convention.
4128 
4129 The states in the main switch are the union of ops and failure/success of
4130 substates associated with with that op.  For example, IFMATCH is the op
4131 that does lookahead assertions /(?=A)B/ and so the IFMATCH state means
4132 'execute IFMATCH'; while IFMATCH_A is a state saying that we have just
4133 successfully matched A and IFMATCH_A_fail is a state saying that we have
4134 just failed to match A. Resume states always come in pairs. The backtrack
4135 state we push is marked as 'IFMATCH_A', but when that is popped, we resume
4136 at IFMATCH_A or IFMATCH_A_fail, depending on whether we are backtracking
4137 on success or failure.
4138 
4139 The struct that holds a backtracking state is actually a big union, with
4140 one variant for each major type of op. The variable st points to the
4141 top-most backtrack struct. To make the code clearer, within each
4142 block of code we #define ST to alias the relevant union.
4143 
4144 Here's a concrete example of a (vastly oversimplified) IFMATCH
4145 implementation:
4146 
4147     switch (state) {
4148     ....
4149 
4150 #define ST st->u.ifmatch
4151 
4152     case IFMATCH: // we are executing the IFMATCH op, (?=A)B
4153 	ST.foo = ...; // some state we wish to save
4154 	...
4155 	// push a yes backtrack state with a resume value of
4156 	// IFMATCH_A/IFMATCH_A_fail, then continue execution at the
4157 	// first node of A:
4158 	PUSH_YES_STATE_GOTO(IFMATCH_A, A, newinput);
4159 	// NOTREACHED
4160 
4161     case IFMATCH_A: // we have successfully executed A; now continue with B
4162 	next = B;
4163 	bar = ST.foo; // do something with the preserved value
4164 	break;
4165 
4166     case IFMATCH_A_fail: // A failed, so the assertion failed
4167 	...;   // do some housekeeping, then ...
4168 	sayNO; // propagate the failure
4169 
4170 #undef ST
4171 
4172     ...
4173     }
4174 
4175 For any old-timers reading this who are familiar with the old recursive
4176 approach, the code above is equivalent to:
4177 
4178     case IFMATCH: // we are executing the IFMATCH op, (?=A)B
4179     {
4180 	int foo = ...
4181 	...
4182 	if (regmatch(A)) {
4183 	    next = B;
4184 	    bar = foo;
4185 	    break;
4186 	}
4187 	...;   // do some housekeeping, then ...
4188 	sayNO; // propagate the failure
4189     }
4190 
4191 The topmost backtrack state, pointed to by st, is usually free. If you
4192 want to claim it, populate any ST.foo fields in it with values you wish to
4193 save, then do one of
4194 
4195 	PUSH_STATE_GOTO(resume_state, node, newinput);
4196 	PUSH_YES_STATE_GOTO(resume_state, node, newinput);
4197 
4198 which sets that backtrack state's resume value to 'resume_state', pushes a
4199 new free entry to the top of the backtrack stack, then goes to 'node'.
4200 On backtracking, the free slot is popped, and the saved state becomes the
4201 new free state. An ST.foo field in this new top state can be temporarily
4202 accessed to retrieve values, but once the main loop is re-entered, it
4203 becomes available for reuse.
4204 
4205 Note that the depth of the backtrack stack constantly increases during the
4206 left-to-right execution of the pattern, rather than going up and down with
4207 the pattern nesting. For example the stack is at its maximum at Z at the
4208 end of the pattern, rather than at X in the following:
4209 
4210     /(((X)+)+)+....(Y)+....Z/
4211 
4212 The only exceptions to this are lookahead/behind assertions and the cut,
4213 (?>A), which pop all the backtrack states associated with A before
4214 continuing.
4215 
4216 Backtrack state structs are allocated in slabs of about 4K in size.
4217 PL_regmatch_state and st always point to the currently active state,
4218 and PL_regmatch_slab points to the slab currently containing
4219 PL_regmatch_state.  The first time regmatch() is called, the first slab is
4220 allocated, and is never freed until interpreter destruction. When the slab
4221 is full, a new one is allocated and chained to the end. At exit from
4222 regmatch(), slabs allocated since entry are freed.
4223 
4224 */
4225 
4226 
4227 #define DEBUG_STATE_pp(pp)                                  \
4228     DEBUG_STATE_r({                                         \
4229         DUMP_EXEC_POS(locinput, scan, utf8_target,depth);   \
4230         Perl_re_printf( aTHX_                                           \
4231             "%*s" pp " %s%s%s%s%s\n",                       \
4232             INDENT_CHARS(depth), "",                        \
4233             PL_reg_name[st->resume_state],                  \
4234             ((st==yes_state||st==mark_state) ? "[" : ""),   \
4235             ((st==yes_state) ? "Y" : ""),                   \
4236             ((st==mark_state) ? "M" : ""),                  \
4237             ((st==yes_state||st==mark_state) ? "]" : "")    \
4238         );                                                  \
4239     });
4240 
4241 
4242 #define REG_NODE_NUM(x) ((x) ? (int)((x)-prog) : -1)
4243 
4244 #ifdef DEBUGGING
4245 
4246 STATIC void
4247 S_debug_start_match(pTHX_ const REGEXP *prog, const bool utf8_target,
4248     const char *start, const char *end, const char *blurb)
4249 {
4250     const bool utf8_pat = RX_UTF8(prog) ? 1 : 0;
4251 
4252     PERL_ARGS_ASSERT_DEBUG_START_MATCH;
4253 
4254     if (!PL_colorset)
4255             reginitcolors();
4256     {
4257         RE_PV_QUOTED_DECL(s0, utf8_pat, PERL_DEBUG_PAD_ZERO(0),
4258             RX_PRECOMP_const(prog), RX_PRELEN(prog), PL_dump_re_max_len);
4259 
4260         RE_PV_QUOTED_DECL(s1, utf8_target, PERL_DEBUG_PAD_ZERO(1),
4261             start, end - start, PL_dump_re_max_len);
4262 
4263         Perl_re_printf( aTHX_
4264             "%s%s REx%s %s against %s\n",
4265 		       PL_colors[4], blurb, PL_colors[5], s0, s1);
4266 
4267         if (utf8_target||utf8_pat)
4268             Perl_re_printf( aTHX_  "UTF-8 %s%s%s...\n",
4269                 utf8_pat ? "pattern" : "",
4270                 utf8_pat && utf8_target ? " and " : "",
4271                 utf8_target ? "string" : ""
4272             );
4273     }
4274 }
4275 
4276 STATIC void
4277 S_dump_exec_pos(pTHX_ const char *locinput,
4278                       const regnode *scan,
4279                       const char *loc_regeol,
4280                       const char *loc_bostr,
4281                       const char *loc_reg_starttry,
4282                       const bool utf8_target,
4283                       const U32 depth
4284                 )
4285 {
4286     const int docolor = *PL_colors[0] || *PL_colors[2] || *PL_colors[4];
4287     const int taill = (docolor ? 10 : 7); /* 3 chars for "> <" */
4288     int l = (loc_regeol - locinput) > taill ? taill : (loc_regeol - locinput);
4289     /* The part of the string before starttry has one color
4290        (pref0_len chars), between starttry and current
4291        position another one (pref_len - pref0_len chars),
4292        after the current position the third one.
4293        We assume that pref0_len <= pref_len, otherwise we
4294        decrease pref0_len.  */
4295     int pref_len = (locinput - loc_bostr) > (5 + taill) - l
4296 	? (5 + taill) - l : locinput - loc_bostr;
4297     int pref0_len;
4298 
4299     PERL_ARGS_ASSERT_DUMP_EXEC_POS;
4300 
4301     while (utf8_target && UTF8_IS_CONTINUATION(*(U8*)(locinput - pref_len)))
4302 	pref_len++;
4303     pref0_len = pref_len  - (locinput - loc_reg_starttry);
4304     if (l + pref_len < (5 + taill) && l < loc_regeol - locinput)
4305 	l = ( loc_regeol - locinput > (5 + taill) - pref_len
4306 	      ? (5 + taill) - pref_len : loc_regeol - locinput);
4307     while (utf8_target && UTF8_IS_CONTINUATION(*(U8*)(locinput + l)))
4308 	l--;
4309     if (pref0_len < 0)
4310 	pref0_len = 0;
4311     if (pref0_len > pref_len)
4312 	pref0_len = pref_len;
4313     {
4314 	const int is_uni = utf8_target ? 1 : 0;
4315 
4316 	RE_PV_COLOR_DECL(s0,len0,is_uni,PERL_DEBUG_PAD(0),
4317 	    (locinput - pref_len),pref0_len, PL_dump_re_max_len, 4, 5);
4318 
4319 	RE_PV_COLOR_DECL(s1,len1,is_uni,PERL_DEBUG_PAD(1),
4320 		    (locinput - pref_len + pref0_len),
4321 		    pref_len - pref0_len, PL_dump_re_max_len, 2, 3);
4322 
4323 	RE_PV_COLOR_DECL(s2,len2,is_uni,PERL_DEBUG_PAD(2),
4324 		    locinput, loc_regeol - locinput, 10, 0, 1);
4325 
4326 	const STRLEN tlen=len0+len1+len2;
4327         Perl_re_printf( aTHX_
4328                     "%4" IVdf " <%.*s%.*s%s%.*s>%*s|%4u| ",
4329 		    (IV)(locinput - loc_bostr),
4330 		    len0, s0,
4331 		    len1, s1,
4332 		    (docolor ? "" : "> <"),
4333 		    len2, s2,
4334 		    (int)(tlen > 19 ? 0 :  19 - tlen),
4335                     "",
4336                     depth);
4337     }
4338 }
4339 
4340 #endif
4341 
4342 /* reg_check_named_buff_matched()
4343  * Checks to see if a named buffer has matched. The data array of
4344  * buffer numbers corresponding to the buffer is expected to reside
4345  * in the regexp->data->data array in the slot stored in the ARG() of
4346  * node involved. Note that this routine doesn't actually care about the
4347  * name, that information is not preserved from compilation to execution.
4348  * Returns the index of the leftmost defined buffer with the given name
4349  * or 0 if non of the buffers matched.
4350  */
4351 STATIC I32
4352 S_reg_check_named_buff_matched(const regexp *rex, const regnode *scan)
4353 {
4354     I32 n;
4355     RXi_GET_DECL(rex,rexi);
4356     SV *sv_dat= MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
4357     I32 *nums=(I32*)SvPVX(sv_dat);
4358 
4359     PERL_ARGS_ASSERT_REG_CHECK_NAMED_BUFF_MATCHED;
4360 
4361     for ( n=0; n<SvIVX(sv_dat); n++ ) {
4362         if ((I32)rex->lastparen >= nums[n] &&
4363             rex->offs[nums[n]].end != -1)
4364         {
4365             return nums[n];
4366         }
4367     }
4368     return 0;
4369 }
4370 
4371 
4372 static bool
4373 S_setup_EXACTISH_ST_c1_c2(pTHX_ const regnode * const text_node, int *c1p,
4374         U8* c1_utf8, int *c2p, U8* c2_utf8, regmatch_info *reginfo)
4375 {
4376     /* This function determines if there are one or two characters that match
4377      * the first character of the passed-in EXACTish node <text_node>, and if
4378      * so, returns them in the passed-in pointers.
4379      *
4380      * If it determines that no possible character in the target string can
4381      * match, it returns FALSE; otherwise TRUE.  (The FALSE situation occurs if
4382      * the first character in <text_node> requires UTF-8 to represent, and the
4383      * target string isn't in UTF-8.)
4384      *
4385      * If there are more than two characters that could match the beginning of
4386      * <text_node>, or if more context is required to determine a match or not,
4387      * it sets both *<c1p> and *<c2p> to CHRTEST_VOID.
4388      *
4389      * The motiviation behind this function is to allow the caller to set up
4390      * tight loops for matching.  If <text_node> is of type EXACT, there is
4391      * only one possible character that can match its first character, and so
4392      * the situation is quite simple.  But things get much more complicated if
4393      * folding is involved.  It may be that the first character of an EXACTFish
4394      * node doesn't participate in any possible fold, e.g., punctuation, so it
4395      * can be matched only by itself.  The vast majority of characters that are
4396      * in folds match just two things, their lower and upper-case equivalents.
4397      * But not all are like that; some have multiple possible matches, or match
4398      * sequences of more than one character.  This function sorts all that out.
4399      *
4400      * Consider the patterns A*B or A*?B where A and B are arbitrary.  In a
4401      * loop of trying to match A*, we know we can't exit where the thing
4402      * following it isn't a B.  And something can't be a B unless it is the
4403      * beginning of B.  By putting a quick test for that beginning in a tight
4404      * loop, we can rule out things that can't possibly be B without having to
4405      * break out of the loop, thus avoiding work.  Similarly, if A is a single
4406      * character, we can make a tight loop matching A*, using the outputs of
4407      * this function.
4408      *
4409      * If the target string to match isn't in UTF-8, and there aren't
4410      * complications which require CHRTEST_VOID, *<c1p> and *<c2p> are set to
4411      * the one or two possible octets (which are characters in this situation)
4412      * that can match.  In all cases, if there is only one character that can
4413      * match, *<c1p> and *<c2p> will be identical.
4414      *
4415      * If the target string is in UTF-8, the buffers pointed to by <c1_utf8>
4416      * and <c2_utf8> will contain the one or two UTF-8 sequences of bytes that
4417      * can match the beginning of <text_node>.  They should be declared with at
4418      * least length UTF8_MAXBYTES+1.  (If the target string isn't in UTF-8, it is
4419      * undefined what these contain.)  If one or both of the buffers are
4420      * invariant under UTF-8, *<c1p>, and *<c2p> will also be set to the
4421      * corresponding invariant.  If variant, the corresponding *<c1p> and/or
4422      * *<c2p> will be set to a negative number(s) that shouldn't match any code
4423      * point (unless inappropriately coerced to unsigned).   *<c1p> will equal
4424      * *<c2p> if and only if <c1_utf8> and <c2_utf8> are the same. */
4425 
4426     const bool utf8_target = reginfo->is_utf8_target;
4427 
4428     UV c1 = (UV)CHRTEST_NOT_A_CP_1;
4429     UV c2 = (UV)CHRTEST_NOT_A_CP_2;
4430     bool use_chrtest_void = FALSE;
4431     const bool is_utf8_pat = reginfo->is_utf8_pat;
4432 
4433     /* Used when we have both utf8 input and utf8 output, to avoid converting
4434      * to/from code points */
4435     bool utf8_has_been_setup = FALSE;
4436 
4437     dVAR;
4438 
4439     U8 *pat = (U8*)STRING(text_node);
4440     U8 folded[UTF8_MAX_FOLD_CHAR_EXPAND * UTF8_MAXBYTES_CASE + 1] = { '\0' };
4441 
4442     if (OP(text_node) == EXACT || OP(text_node) == EXACTL) {
4443 
4444         /* In an exact node, only one thing can be matched, that first
4445          * character.  If both the pat and the target are UTF-8, we can just
4446          * copy the input to the output, avoiding finding the code point of
4447          * that character */
4448         if (!is_utf8_pat) {
4449             c2 = c1 = *pat;
4450         }
4451         else if (utf8_target) {
4452             Copy(pat, c1_utf8, UTF8SKIP(pat), U8);
4453             Copy(pat, c2_utf8, UTF8SKIP(pat), U8);
4454             utf8_has_been_setup = TRUE;
4455         }
4456         else {
4457             c2 = c1 = valid_utf8_to_uvchr(pat, NULL);
4458         }
4459     }
4460     else { /* an EXACTFish node */
4461         U8 *pat_end = pat + STR_LEN(text_node);
4462 
4463         /* An EXACTFL node has at least some characters unfolded, because what
4464          * they match is not known until now.  So, now is the time to fold
4465          * the first few of them, as many as are needed to determine 'c1' and
4466          * 'c2' later in the routine.  If the pattern isn't UTF-8, we only need
4467          * to fold if in a UTF-8 locale, and then only the Sharp S; everything
4468          * else is 1-1 and isn't assumed to be folded.  In a UTF-8 pattern, we
4469          * need to fold as many characters as a single character can fold to,
4470          * so that later we can check if the first ones are such a multi-char
4471          * fold.  But, in such a pattern only locale-problematic characters
4472          * aren't folded, so we can skip this completely if the first character
4473          * in the node isn't one of the tricky ones */
4474         if (OP(text_node) == EXACTFL) {
4475 
4476             if (! is_utf8_pat) {
4477                 if (IN_UTF8_CTYPE_LOCALE && *pat == LATIN_SMALL_LETTER_SHARP_S)
4478                 {
4479                     folded[0] = folded[1] = 's';
4480                     pat = folded;
4481                     pat_end = folded + 2;
4482                 }
4483             }
4484             else if (is_PROBLEMATIC_LOCALE_FOLDEDS_START_utf8(pat)) {
4485                 U8 *s = pat;
4486                 U8 *d = folded;
4487                 int i;
4488 
4489                 for (i = 0; i < UTF8_MAX_FOLD_CHAR_EXPAND && s < pat_end; i++) {
4490                     if (isASCII(*s)) {
4491                         *(d++) = (U8) toFOLD_LC(*s);
4492                         s++;
4493                     }
4494                     else {
4495                         STRLEN len;
4496                         _toFOLD_utf8_flags(s,
4497                                            pat_end,
4498                                            d,
4499                                            &len,
4500                                            FOLD_FLAGS_FULL | FOLD_FLAGS_LOCALE);
4501                         d += len;
4502                         s += UTF8SKIP(s);
4503                     }
4504                 }
4505 
4506                 pat = folded;
4507                 pat_end = d;
4508             }
4509         }
4510 
4511         if ((is_utf8_pat && is_MULTI_CHAR_FOLD_utf8_safe(pat, pat_end))
4512              || (!is_utf8_pat && is_MULTI_CHAR_FOLD_latin1_safe(pat, pat_end)))
4513         {
4514             /* Multi-character folds require more context to sort out.  Also
4515              * PL_utf8_foldclosures used below doesn't handle them, so have to
4516              * be handled outside this routine */
4517             use_chrtest_void = TRUE;
4518         }
4519         else { /* an EXACTFish node which doesn't begin with a multi-char fold */
4520             c1 = is_utf8_pat ? valid_utf8_to_uvchr(pat, NULL) : *pat;
4521             if (c1 > 255) {
4522                 const unsigned int * remaining_folds_to_list;
4523                 unsigned int first_folds_to;
4524 
4525                 /* Look up what code points (besides c1) fold to c1;  e.g.,
4526                  * [ 'K', KELVIN_SIGN ] both fold to 'k'. */
4527                 Size_t folds_to_count = _inverse_folds(c1,
4528                                                      &first_folds_to,
4529                                                      &remaining_folds_to_list);
4530                 if (folds_to_count == 0) {
4531                     c2 = c1;    /* there is only a single character that could
4532                                    match */
4533                 }
4534                 else if (folds_to_count != 1) {
4535                     /* If there aren't exactly two folds to this (itself and
4536                      * another), it is outside the scope of this function */
4537                     use_chrtest_void = TRUE;
4538                 }
4539                 else {  /* There are two.  We already have one, get the other */
4540                     c2 = first_folds_to;
4541 
4542                     /* Folds that cross the 255/256 boundary are forbidden if
4543                      * EXACTFL (and isnt a UTF8 locale), or EXACTFAA and one is
4544                      * ASCIII.  The only other match to c1 is c2, and since c1
4545                      * is above 255, c2 better be as well under these
4546                      * circumstances.  If it isn't, it means the only legal
4547                      * match of c1 is itself. */
4548                     if (    c2 < 256
4549                         && (   (   OP(text_node) == EXACTFL
4550                                 && ! IN_UTF8_CTYPE_LOCALE)
4551                             || ((     OP(text_node) == EXACTFAA
4552                                    || OP(text_node) == EXACTFAA_NO_TRIE)
4553                                 && (isASCII(c1) || isASCII(c2)))))
4554                     {
4555                         c2 = c1;
4556                     }
4557                 }
4558             }
4559             else /* Here, c1 is <= 255 */
4560                 if (utf8_target
4561                     && HAS_NONLATIN1_FOLD_CLOSURE(c1)
4562                     && ( ! (OP(text_node) == EXACTFL && ! IN_UTF8_CTYPE_LOCALE))
4563                     && ((OP(text_node) != EXACTFAA
4564                         && OP(text_node) != EXACTFAA_NO_TRIE)
4565                         || ! isASCII(c1)))
4566             {
4567                 /* Here, there could be something above Latin1 in the target
4568                  * which folds to this character in the pattern.  All such
4569                  * cases except LATIN SMALL LETTER Y WITH DIAERESIS have more
4570                  * than two characters involved in their folds, so are outside
4571                  * the scope of this function */
4572                 if (UNLIKELY(c1 == LATIN_SMALL_LETTER_Y_WITH_DIAERESIS)) {
4573                     c2 = LATIN_CAPITAL_LETTER_Y_WITH_DIAERESIS;
4574                 }
4575                 else {
4576                     use_chrtest_void = TRUE;
4577                 }
4578             }
4579             else { /* Here nothing above Latin1 can fold to the pattern
4580                       character */
4581                 switch (OP(text_node)) {
4582 
4583                     case EXACTFL:   /* /l rules */
4584                         c2 = PL_fold_locale[c1];
4585                         break;
4586 
4587                     case EXACTF:   /* This node only generated for non-utf8
4588                                     patterns */
4589                         assert(! is_utf8_pat);
4590                         if (! utf8_target) {    /* /d rules */
4591                             c2 = PL_fold[c1];
4592                             break;
4593                         }
4594                         /* FALLTHROUGH */
4595                         /* /u rules for all these.  This happens to work for
4596                         * EXACTFAA as nothing in Latin1 folds to ASCII */
4597                     case EXACTFAA_NO_TRIE:   /* This node only generated for
4598                                                 non-utf8 patterns */
4599                         assert(! is_utf8_pat);
4600                         /* FALLTHROUGH */
4601                     case EXACTFAA:
4602                     case EXACTFU_SS:
4603                     case EXACTFU:
4604                         c2 = PL_fold_latin1[c1];
4605                         break;
4606 
4607                     default:
4608                         Perl_croak(aTHX_ "panic: Unexpected op %u", OP(text_node));
4609                         NOT_REACHED; /* NOTREACHED */
4610                 }
4611             }
4612         }
4613     }
4614 
4615     /* Here have figured things out.  Set up the returns */
4616     if (use_chrtest_void) {
4617         *c2p = *c1p = CHRTEST_VOID;
4618     }
4619     else if (utf8_target) {
4620         if (! utf8_has_been_setup) {    /* Don't have the utf8; must get it */
4621             uvchr_to_utf8(c1_utf8, c1);
4622             uvchr_to_utf8(c2_utf8, c2);
4623         }
4624 
4625         /* Invariants are stored in both the utf8 and byte outputs; Use
4626          * negative numbers otherwise for the byte ones.  Make sure that the
4627          * byte ones are the same iff the utf8 ones are the same */
4628         *c1p = (UTF8_IS_INVARIANT(*c1_utf8)) ? *c1_utf8 : CHRTEST_NOT_A_CP_1;
4629         *c2p = (UTF8_IS_INVARIANT(*c2_utf8))
4630                 ? *c2_utf8
4631                 : (c1 == c2)
4632                   ? CHRTEST_NOT_A_CP_1
4633                   : CHRTEST_NOT_A_CP_2;
4634     }
4635     else if (c1 > 255) {
4636        if (c2 > 255) {  /* both possibilities are above what a non-utf8 string
4637                            can represent */
4638            return FALSE;
4639        }
4640 
4641        *c1p = *c2p = c2;    /* c2 is the only representable value */
4642     }
4643     else {  /* c1 is representable; see about c2 */
4644        *c1p = c1;
4645        *c2p = (c2 < 256) ? c2 : c1;
4646     }
4647 
4648     return TRUE;
4649 }
4650 
4651 STATIC bool
4652 S_isGCB(pTHX_ const GCB_enum before, const GCB_enum after, const U8 * const strbeg, const U8 * const curpos, const bool utf8_target)
4653 {
4654     /* returns a boolean indicating if there is a Grapheme Cluster Boundary
4655      * between the inputs.  See http://www.unicode.org/reports/tr29/. */
4656 
4657     PERL_ARGS_ASSERT_ISGCB;
4658 
4659     switch (GCB_table[before][after]) {
4660         case GCB_BREAKABLE:
4661             return TRUE;
4662 
4663         case GCB_NOBREAK:
4664             return FALSE;
4665 
4666         case GCB_RI_then_RI:
4667             {
4668                 int RI_count = 1;
4669                 U8 * temp_pos = (U8 *) curpos;
4670 
4671                 /* Do not break within emoji flag sequences. That is, do not
4672                  * break between regional indicator (RI) symbols if there is an
4673                  * odd number of RI characters before the break point.
4674                  *  GB12   sot (RI RI)* RI × RI
4675                  *  GB13 [^RI] (RI RI)* RI × RI */
4676 
4677                 while (backup_one_GCB(strbeg,
4678                                     &temp_pos,
4679                                     utf8_target) == GCB_Regional_Indicator)
4680                 {
4681                     RI_count++;
4682                 }
4683 
4684                 return RI_count % 2 != 1;
4685             }
4686 
4687         case GCB_EX_then_EM:
4688 
4689             /* GB10  ( E_Base | E_Base_GAZ ) Extend* ×  E_Modifier */
4690             {
4691                 U8 * temp_pos = (U8 *) curpos;
4692                 GCB_enum prev;
4693 
4694                 do {
4695                     prev = backup_one_GCB(strbeg, &temp_pos, utf8_target);
4696                 }
4697                 while (prev == GCB_Extend);
4698 
4699                 return prev != GCB_E_Base && prev != GCB_E_Base_GAZ;
4700             }
4701 
4702         default:
4703             break;
4704     }
4705 
4706 #ifdef DEBUGGING
4707     Perl_re_printf( aTHX_  "Unhandled GCB pair: GCB_table[%d, %d] = %d\n",
4708                                   before, after, GCB_table[before][after]);
4709     assert(0);
4710 #endif
4711     return TRUE;
4712 }
4713 
4714 STATIC GCB_enum
4715 S_backup_one_GCB(pTHX_ const U8 * const strbeg, U8 ** curpos, const bool utf8_target)
4716 {
4717     GCB_enum gcb;
4718 
4719     PERL_ARGS_ASSERT_BACKUP_ONE_GCB;
4720 
4721     if (*curpos < strbeg) {
4722         return GCB_EDGE;
4723     }
4724 
4725     if (utf8_target) {
4726         U8 * prev_char_pos = reghopmaybe3(*curpos, -1, strbeg);
4727         U8 * prev_prev_char_pos;
4728 
4729         if (! prev_char_pos) {
4730             return GCB_EDGE;
4731         }
4732 
4733         if ((prev_prev_char_pos = reghopmaybe3((U8 *) prev_char_pos, -1, strbeg))) {
4734             gcb = getGCB_VAL_UTF8(prev_prev_char_pos, prev_char_pos);
4735             *curpos = prev_char_pos;
4736             prev_char_pos = prev_prev_char_pos;
4737         }
4738         else {
4739             *curpos = (U8 *) strbeg;
4740             return GCB_EDGE;
4741         }
4742     }
4743     else {
4744         if (*curpos - 2 < strbeg) {
4745             *curpos = (U8 *) strbeg;
4746             return GCB_EDGE;
4747         }
4748         (*curpos)--;
4749         gcb = getGCB_VAL_CP(*(*curpos - 1));
4750     }
4751 
4752     return gcb;
4753 }
4754 
4755 /* Combining marks attach to most classes that precede them, but this defines
4756  * the exceptions (from TR14) */
4757 #define LB_CM_ATTACHES_TO(prev) ( ! (   prev == LB_EDGE                 \
4758                                      || prev == LB_Mandatory_Break      \
4759                                      || prev == LB_Carriage_Return      \
4760                                      || prev == LB_Line_Feed            \
4761                                      || prev == LB_Next_Line            \
4762                                      || prev == LB_Space                \
4763                                      || prev == LB_ZWSpace))
4764 
4765 STATIC bool
4766 S_isLB(pTHX_ LB_enum before,
4767              LB_enum after,
4768              const U8 * const strbeg,
4769              const U8 * const curpos,
4770              const U8 * const strend,
4771              const bool utf8_target)
4772 {
4773     U8 * temp_pos = (U8 *) curpos;
4774     LB_enum prev = before;
4775 
4776     /* Is the boundary between 'before' and 'after' line-breakable?
4777      * Most of this is just a table lookup of a generated table from Unicode
4778      * rules.  But some rules require context to decide, and so have to be
4779      * implemented in code */
4780 
4781     PERL_ARGS_ASSERT_ISLB;
4782 
4783     /* Rule numbers in the comments below are as of Unicode 9.0 */
4784 
4785   redo:
4786     before = prev;
4787     switch (LB_table[before][after]) {
4788         case LB_BREAKABLE:
4789             return TRUE;
4790 
4791         case LB_NOBREAK:
4792         case LB_NOBREAK_EVEN_WITH_SP_BETWEEN:
4793             return FALSE;
4794 
4795         case LB_SP_foo + LB_BREAKABLE:
4796         case LB_SP_foo + LB_NOBREAK:
4797         case LB_SP_foo + LB_NOBREAK_EVEN_WITH_SP_BETWEEN:
4798 
4799             /* When we have something following a SP, we have to look at the
4800              * context in order to know what to do.
4801              *
4802              * SP SP should not reach here because LB7: Do not break before
4803              * spaces.  (For two spaces in a row there is nothing that
4804              * overrides that) */
4805             assert(after != LB_Space);
4806 
4807             /* Here we have a space followed by a non-space.  Mostly this is a
4808              * case of LB18: "Break after spaces".  But there are complications
4809              * as the handling of spaces is somewhat tricky.  They are in a
4810              * number of rules, which have to be applied in priority order, but
4811              * something earlier in the string can cause a rule to be skipped
4812              * and a lower priority rule invoked.  A prime example is LB7 which
4813              * says don't break before a space.  But rule LB8 (lower priority)
4814              * says that the first break opportunity after a ZW is after any
4815              * span of spaces immediately after it.  If a ZW comes before a SP
4816              * in the input, rule LB8 applies, and not LB7.  Other such rules
4817              * involve combining marks which are rules 9 and 10, but they may
4818              * override higher priority rules if they come earlier in the
4819              * string.  Since we're doing random access into the middle of the
4820              * string, we have to look for rules that should get applied based
4821              * on both string position and priority.  Combining marks do not
4822              * attach to either ZW nor SP, so we don't have to consider them
4823              * until later.
4824              *
4825              * To check for LB8, we have to find the first non-space character
4826              * before this span of spaces */
4827             do {
4828                 prev = backup_one_LB(strbeg, &temp_pos, utf8_target);
4829             }
4830             while (prev == LB_Space);
4831 
4832             /* LB8 Break before any character following a zero-width space,
4833              * even if one or more spaces intervene.
4834              *      ZW SP* ÷
4835              * So if we have a ZW just before this span, and to get here this
4836              * is the final space in the span. */
4837             if (prev == LB_ZWSpace) {
4838                 return TRUE;
4839             }
4840 
4841             /* Here, not ZW SP+.  There are several rules that have higher
4842              * priority than LB18 and can be resolved now, as they don't depend
4843              * on anything earlier in the string (except ZW, which we have
4844              * already handled).  One of these rules is LB11 Do not break
4845              * before Word joiner, but we have specially encoded that in the
4846              * lookup table so it is caught by the single test below which
4847              * catches the other ones. */
4848             if (LB_table[LB_Space][after] - LB_SP_foo
4849                                             == LB_NOBREAK_EVEN_WITH_SP_BETWEEN)
4850             {
4851                 return FALSE;
4852             }
4853 
4854             /* If we get here, we have to XXX consider combining marks. */
4855             if (prev == LB_Combining_Mark) {
4856 
4857                 /* What happens with these depends on the character they
4858                  * follow.  */
4859                 do {
4860                     prev = backup_one_LB(strbeg, &temp_pos, utf8_target);
4861                 }
4862                 while (prev == LB_Combining_Mark);
4863 
4864                 /* Most times these attach to and inherit the characteristics
4865                  * of that character, but not always, and when not, they are to
4866                  * be treated as AL by rule LB10. */
4867                 if (! LB_CM_ATTACHES_TO(prev)) {
4868                     prev = LB_Alphabetic;
4869                 }
4870             }
4871 
4872             /* Here, we have the character preceding the span of spaces all set
4873              * up.  We follow LB18: "Break after spaces" unless the table shows
4874              * that is overriden */
4875             return LB_table[prev][after] != LB_NOBREAK_EVEN_WITH_SP_BETWEEN;
4876 
4877         case LB_CM_ZWJ_foo:
4878 
4879             /* We don't know how to treat the CM except by looking at the first
4880              * non-CM character preceding it.  ZWJ is treated as CM */
4881             do {
4882                 prev = backup_one_LB(strbeg, &temp_pos, utf8_target);
4883             }
4884             while (prev == LB_Combining_Mark || prev == LB_ZWJ);
4885 
4886             /* Here, 'prev' is that first earlier non-CM character.  If the CM
4887              * attatches to it, then it inherits the behavior of 'prev'.  If it
4888              * doesn't attach, it is to be treated as an AL */
4889             if (! LB_CM_ATTACHES_TO(prev)) {
4890                 prev = LB_Alphabetic;
4891             }
4892 
4893             goto redo;
4894 
4895         case LB_HY_or_BA_then_foo + LB_BREAKABLE:
4896         case LB_HY_or_BA_then_foo + LB_NOBREAK:
4897 
4898             /* LB21a Don't break after Hebrew + Hyphen.
4899              * HL (HY | BA) × */
4900 
4901             if (backup_one_LB(strbeg, &temp_pos, utf8_target)
4902                                                           == LB_Hebrew_Letter)
4903             {
4904                 return FALSE;
4905             }
4906 
4907             return LB_table[prev][after] - LB_HY_or_BA_then_foo == LB_BREAKABLE;
4908 
4909         case LB_PR_or_PO_then_OP_or_HY + LB_BREAKABLE:
4910         case LB_PR_or_PO_then_OP_or_HY + LB_NOBREAK:
4911 
4912             /* LB25a (PR | PO) × ( OP | HY )? NU */
4913             if (advance_one_LB(&temp_pos, strend, utf8_target) == LB_Numeric) {
4914                 return FALSE;
4915             }
4916 
4917             return LB_table[prev][after] - LB_PR_or_PO_then_OP_or_HY
4918                                                                 == LB_BREAKABLE;
4919 
4920         case LB_SY_or_IS_then_various + LB_BREAKABLE:
4921         case LB_SY_or_IS_then_various + LB_NOBREAK:
4922         {
4923             /* LB25d NU (SY | IS)* × (NU | SY | IS | CL | CP ) */
4924 
4925             LB_enum temp = prev;
4926             do {
4927                 temp = backup_one_LB(strbeg, &temp_pos, utf8_target);
4928             }
4929             while (temp == LB_Break_Symbols || temp == LB_Infix_Numeric);
4930             if (temp == LB_Numeric) {
4931                 return FALSE;
4932             }
4933 
4934             return LB_table[prev][after] - LB_SY_or_IS_then_various
4935                                                                == LB_BREAKABLE;
4936         }
4937 
4938         case LB_various_then_PO_or_PR + LB_BREAKABLE:
4939         case LB_various_then_PO_or_PR + LB_NOBREAK:
4940         {
4941             /* LB25e NU (SY | IS)* (CL | CP)? × (PO | PR) */
4942 
4943             LB_enum temp = prev;
4944             if (temp == LB_Close_Punctuation || temp == LB_Close_Parenthesis)
4945             {
4946                 temp = backup_one_LB(strbeg, &temp_pos, utf8_target);
4947             }
4948             while (temp == LB_Break_Symbols || temp == LB_Infix_Numeric) {
4949                 temp = backup_one_LB(strbeg, &temp_pos, utf8_target);
4950             }
4951             if (temp == LB_Numeric) {
4952                 return FALSE;
4953             }
4954             return LB_various_then_PO_or_PR;
4955         }
4956 
4957         case LB_RI_then_RI + LB_NOBREAK:
4958         case LB_RI_then_RI + LB_BREAKABLE:
4959             {
4960                 int RI_count = 1;
4961 
4962                 /* LB30a Break between two regional indicator symbols if and
4963                  * only if there are an even number of regional indicators
4964                  * preceding the position of the break.
4965                  *
4966                  *    sot (RI RI)* RI × RI
4967                  *  [^RI] (RI RI)* RI × RI */
4968 
4969                 while (backup_one_LB(strbeg,
4970                                      &temp_pos,
4971                                      utf8_target) == LB_Regional_Indicator)
4972                 {
4973                     RI_count++;
4974                 }
4975 
4976                 return RI_count % 2 == 0;
4977             }
4978 
4979         default:
4980             break;
4981     }
4982 
4983 #ifdef DEBUGGING
4984     Perl_re_printf( aTHX_  "Unhandled LB pair: LB_table[%d, %d] = %d\n",
4985                                   before, after, LB_table[before][after]);
4986     assert(0);
4987 #endif
4988     return TRUE;
4989 }
4990 
4991 STATIC LB_enum
4992 S_advance_one_LB(pTHX_ U8 ** curpos, const U8 * const strend, const bool utf8_target)
4993 {
4994     LB_enum lb;
4995 
4996     PERL_ARGS_ASSERT_ADVANCE_ONE_LB;
4997 
4998     if (*curpos >= strend) {
4999         return LB_EDGE;
5000     }
5001 
5002     if (utf8_target) {
5003         *curpos += UTF8SKIP(*curpos);
5004         if (*curpos >= strend) {
5005             return LB_EDGE;
5006         }
5007         lb = getLB_VAL_UTF8(*curpos, strend);
5008     }
5009     else {
5010         (*curpos)++;
5011         if (*curpos >= strend) {
5012             return LB_EDGE;
5013         }
5014         lb = getLB_VAL_CP(**curpos);
5015     }
5016 
5017     return lb;
5018 }
5019 
5020 STATIC LB_enum
5021 S_backup_one_LB(pTHX_ const U8 * const strbeg, U8 ** curpos, const bool utf8_target)
5022 {
5023     LB_enum lb;
5024 
5025     PERL_ARGS_ASSERT_BACKUP_ONE_LB;
5026 
5027     if (*curpos < strbeg) {
5028         return LB_EDGE;
5029     }
5030 
5031     if (utf8_target) {
5032         U8 * prev_char_pos = reghopmaybe3(*curpos, -1, strbeg);
5033         U8 * prev_prev_char_pos;
5034 
5035         if (! prev_char_pos) {
5036             return LB_EDGE;
5037         }
5038 
5039         if ((prev_prev_char_pos = reghopmaybe3((U8 *) prev_char_pos, -1, strbeg))) {
5040             lb = getLB_VAL_UTF8(prev_prev_char_pos, prev_char_pos);
5041             *curpos = prev_char_pos;
5042             prev_char_pos = prev_prev_char_pos;
5043         }
5044         else {
5045             *curpos = (U8 *) strbeg;
5046             return LB_EDGE;
5047         }
5048     }
5049     else {
5050         if (*curpos - 2 < strbeg) {
5051             *curpos = (U8 *) strbeg;
5052             return LB_EDGE;
5053         }
5054         (*curpos)--;
5055         lb = getLB_VAL_CP(*(*curpos - 1));
5056     }
5057 
5058     return lb;
5059 }
5060 
5061 STATIC bool
5062 S_isSB(pTHX_ SB_enum before,
5063              SB_enum after,
5064              const U8 * const strbeg,
5065              const U8 * const curpos,
5066              const U8 * const strend,
5067              const bool utf8_target)
5068 {
5069     /* returns a boolean indicating if there is a Sentence Boundary Break
5070      * between the inputs.  See http://www.unicode.org/reports/tr29/ */
5071 
5072     U8 * lpos = (U8 *) curpos;
5073     bool has_para_sep = FALSE;
5074     bool has_sp = FALSE;
5075 
5076     PERL_ARGS_ASSERT_ISSB;
5077 
5078     /* Break at the start and end of text.
5079         SB1.  sot  ÷
5080         SB2.  ÷  eot
5081       But unstated in Unicode is don't break if the text is empty */
5082     if (before == SB_EDGE || after == SB_EDGE) {
5083         return before != after;
5084     }
5085 
5086     /* SB 3: Do not break within CRLF. */
5087     if (before == SB_CR && after == SB_LF) {
5088         return FALSE;
5089     }
5090 
5091     /* Break after paragraph separators.  CR and LF are considered
5092      * so because Unicode views text as like word processing text where there
5093      * are no newlines except between paragraphs, and the word processor takes
5094      * care of wrapping without there being hard line-breaks in the text *./
5095        SB4.  Sep | CR | LF  ÷ */
5096     if (before == SB_Sep || before == SB_CR || before == SB_LF) {
5097         return TRUE;
5098     }
5099 
5100     /* Ignore Format and Extend characters, except after sot, Sep, CR, or LF.
5101      * (See Section 6.2, Replacing Ignore Rules.)
5102         SB5.  X (Extend | Format)*  →  X */
5103     if (after == SB_Extend || after == SB_Format) {
5104 
5105         /* Implied is that the these characters attach to everything
5106          * immediately prior to them except for those separator-type
5107          * characters.  And the rules earlier have already handled the case
5108          * when one of those immediately precedes the extend char */
5109         return FALSE;
5110     }
5111 
5112     if (before == SB_Extend || before == SB_Format) {
5113         U8 * temp_pos = lpos;
5114         const SB_enum backup = backup_one_SB(strbeg, &temp_pos, utf8_target);
5115         if (   backup != SB_EDGE
5116             && backup != SB_Sep
5117             && backup != SB_CR
5118             && backup != SB_LF)
5119         {
5120             before = backup;
5121             lpos = temp_pos;
5122         }
5123 
5124         /* Here, both 'before' and 'backup' are these types; implied is that we
5125          * don't break between them */
5126         if (backup == SB_Extend || backup == SB_Format) {
5127             return FALSE;
5128         }
5129     }
5130 
5131     /* Do not break after ambiguous terminators like period, if they are
5132      * immediately followed by a number or lowercase letter, if they are
5133      * between uppercase letters, if the first following letter (optionally
5134      * after certain punctuation) is lowercase, or if they are followed by
5135      * "continuation" punctuation such as comma, colon, or semicolon. For
5136      * example, a period may be an abbreviation or numeric period, and thus may
5137      * not mark the end of a sentence.
5138 
5139      * SB6. ATerm  ×  Numeric */
5140     if (before == SB_ATerm && after == SB_Numeric) {
5141         return FALSE;
5142     }
5143 
5144     /* SB7.  (Upper | Lower) ATerm  ×  Upper */
5145     if (before == SB_ATerm && after == SB_Upper) {
5146         U8 * temp_pos = lpos;
5147         SB_enum backup = backup_one_SB(strbeg, &temp_pos, utf8_target);
5148         if (backup == SB_Upper || backup == SB_Lower) {
5149             return FALSE;
5150         }
5151     }
5152 
5153     /* The remaining rules that aren't the final one, all require an STerm or
5154      * an ATerm after having backed up over some Close* Sp*, and in one case an
5155      * optional Paragraph separator, although one rule doesn't have any Sp's in it.
5156      * So do that backup now, setting flags if either Sp or a paragraph
5157      * separator are found */
5158 
5159     if (before == SB_Sep || before == SB_CR || before == SB_LF) {
5160         has_para_sep = TRUE;
5161         before = backup_one_SB(strbeg, &lpos, utf8_target);
5162     }
5163 
5164     if (before == SB_Sp) {
5165         has_sp = TRUE;
5166         do {
5167             before = backup_one_SB(strbeg, &lpos, utf8_target);
5168         }
5169         while (before == SB_Sp);
5170     }
5171 
5172     while (before == SB_Close) {
5173         before = backup_one_SB(strbeg, &lpos, utf8_target);
5174     }
5175 
5176     /* The next few rules apply only when the backed-up-to is an ATerm, and in
5177      * most cases an STerm */
5178     if (before == SB_STerm || before == SB_ATerm) {
5179 
5180         /* So, here the lhs matches
5181          *      (STerm | ATerm) Close* Sp* (Sep | CR | LF)?
5182          * and we have set flags if we found an Sp, or the optional Sep,CR,LF.
5183          * The rules that apply here are:
5184          *
5185          * SB8    ATerm Close* Sp*  ×  ( ¬(OLetter | Upper | Lower | Sep | CR
5186                                            | LF | STerm | ATerm) )* Lower
5187            SB8a  (STerm | ATerm) Close* Sp*  ×  (SContinue | STerm | ATerm)
5188            SB9   (STerm | ATerm) Close*  ×  (Close | Sp | Sep | CR | LF)
5189            SB10  (STerm | ATerm) Close* Sp*  ×  (Sp | Sep | CR | LF)
5190            SB11  (STerm | ATerm) Close* Sp* (Sep | CR | LF)?  ÷
5191          */
5192 
5193         /* And all but SB11 forbid having seen a paragraph separator */
5194         if (! has_para_sep) {
5195             if (before == SB_ATerm) {          /* SB8 */
5196                 U8 * rpos = (U8 *) curpos;
5197                 SB_enum later = after;
5198 
5199                 while (    later != SB_OLetter
5200                         && later != SB_Upper
5201                         && later != SB_Lower
5202                         && later != SB_Sep
5203                         && later != SB_CR
5204                         && later != SB_LF
5205                         && later != SB_STerm
5206                         && later != SB_ATerm
5207                         && later != SB_EDGE)
5208                 {
5209                     later = advance_one_SB(&rpos, strend, utf8_target);
5210                 }
5211                 if (later == SB_Lower) {
5212                     return FALSE;
5213                 }
5214             }
5215 
5216             if (   after == SB_SContinue    /* SB8a */
5217                 || after == SB_STerm
5218                 || after == SB_ATerm)
5219             {
5220                 return FALSE;
5221             }
5222 
5223             if (! has_sp) {     /* SB9 applies only if there was no Sp* */
5224                 if (   after == SB_Close
5225                     || after == SB_Sp
5226                     || after == SB_Sep
5227                     || after == SB_CR
5228                     || after == SB_LF)
5229                 {
5230                     return FALSE;
5231                 }
5232             }
5233 
5234             /* SB10.  This and SB9 could probably be combined some way, but khw
5235              * has decided to follow the Unicode rule book precisely for
5236              * simplified maintenance */
5237             if (   after == SB_Sp
5238                 || after == SB_Sep
5239                 || after == SB_CR
5240                 || after == SB_LF)
5241             {
5242                 return FALSE;
5243             }
5244         }
5245 
5246         /* SB11.  */
5247         return TRUE;
5248     }
5249 
5250     /* Otherwise, do not break.
5251     SB12.  Any  ×  Any */
5252 
5253     return FALSE;
5254 }
5255 
5256 STATIC SB_enum
5257 S_advance_one_SB(pTHX_ U8 ** curpos, const U8 * const strend, const bool utf8_target)
5258 {
5259     SB_enum sb;
5260 
5261     PERL_ARGS_ASSERT_ADVANCE_ONE_SB;
5262 
5263     if (*curpos >= strend) {
5264         return SB_EDGE;
5265     }
5266 
5267     if (utf8_target) {
5268         do {
5269             *curpos += UTF8SKIP(*curpos);
5270             if (*curpos >= strend) {
5271                 return SB_EDGE;
5272             }
5273             sb = getSB_VAL_UTF8(*curpos, strend);
5274         } while (sb == SB_Extend || sb == SB_Format);
5275     }
5276     else {
5277         do {
5278             (*curpos)++;
5279             if (*curpos >= strend) {
5280                 return SB_EDGE;
5281             }
5282             sb = getSB_VAL_CP(**curpos);
5283         } while (sb == SB_Extend || sb == SB_Format);
5284     }
5285 
5286     return sb;
5287 }
5288 
5289 STATIC SB_enum
5290 S_backup_one_SB(pTHX_ const U8 * const strbeg, U8 ** curpos, const bool utf8_target)
5291 {
5292     SB_enum sb;
5293 
5294     PERL_ARGS_ASSERT_BACKUP_ONE_SB;
5295 
5296     if (*curpos < strbeg) {
5297         return SB_EDGE;
5298     }
5299 
5300     if (utf8_target) {
5301         U8 * prev_char_pos = reghopmaybe3(*curpos, -1, strbeg);
5302         if (! prev_char_pos) {
5303             return SB_EDGE;
5304         }
5305 
5306         /* Back up over Extend and Format.  curpos is always just to the right
5307          * of the characater whose value we are getting */
5308         do {
5309             U8 * prev_prev_char_pos;
5310             if ((prev_prev_char_pos = reghopmaybe3((U8 *) prev_char_pos, -1,
5311                                                                       strbeg)))
5312             {
5313                 sb = getSB_VAL_UTF8(prev_prev_char_pos, prev_char_pos);
5314                 *curpos = prev_char_pos;
5315                 prev_char_pos = prev_prev_char_pos;
5316             }
5317             else {
5318                 *curpos = (U8 *) strbeg;
5319                 return SB_EDGE;
5320             }
5321         } while (sb == SB_Extend || sb == SB_Format);
5322     }
5323     else {
5324         do {
5325             if (*curpos - 2 < strbeg) {
5326                 *curpos = (U8 *) strbeg;
5327                 return SB_EDGE;
5328             }
5329             (*curpos)--;
5330             sb = getSB_VAL_CP(*(*curpos - 1));
5331         } while (sb == SB_Extend || sb == SB_Format);
5332     }
5333 
5334     return sb;
5335 }
5336 
5337 STATIC bool
5338 S_isWB(pTHX_ WB_enum previous,
5339              WB_enum before,
5340              WB_enum after,
5341              const U8 * const strbeg,
5342              const U8 * const curpos,
5343              const U8 * const strend,
5344              const bool utf8_target)
5345 {
5346     /*  Return a boolean as to if the boundary between 'before' and 'after' is
5347      *  a Unicode word break, using their published algorithm, but tailored for
5348      *  Perl by treating spans of white space as one unit.  Context may be
5349      *  needed to make this determination.  If the value for the character
5350      *  before 'before' is known, it is passed as 'previous'; otherwise that
5351      *  should be set to WB_UNKNOWN.  The other input parameters give the
5352      *  boundaries and current position in the matching of the string.  That
5353      *  is, 'curpos' marks the position where the character whose wb value is
5354      *  'after' begins.  See http://www.unicode.org/reports/tr29/ */
5355 
5356     U8 * before_pos = (U8 *) curpos;
5357     U8 * after_pos = (U8 *) curpos;
5358     WB_enum prev = before;
5359     WB_enum next;
5360 
5361     PERL_ARGS_ASSERT_ISWB;
5362 
5363     /* Rule numbers in the comments below are as of Unicode 9.0 */
5364 
5365   redo:
5366     before = prev;
5367     switch (WB_table[before][after]) {
5368         case WB_BREAKABLE:
5369             return TRUE;
5370 
5371         case WB_NOBREAK:
5372             return FALSE;
5373 
5374         case WB_hs_then_hs:     /* 2 horizontal spaces in a row */
5375             next = advance_one_WB(&after_pos, strend, utf8_target,
5376                                  FALSE /* Don't skip Extend nor Format */ );
5377             /* A space immediately preceeding an Extend or Format is attached
5378              * to by them, and hence gets separated from previous spaces.
5379              * Otherwise don't break between horizontal white space */
5380             return next == WB_Extend || next == WB_Format;
5381 
5382         /* WB4 Ignore Format and Extend characters, except when they appear at
5383          * the beginning of a region of text.  This code currently isn't
5384          * general purpose, but it works as the rules are currently and likely
5385          * to be laid out.  The reason it works is that when 'they appear at
5386          * the beginning of a region of text', the rule is to break before
5387          * them, just like any other character.  Therefore, the default rule
5388          * applies and we don't have to look in more depth.  Should this ever
5389          * change, we would have to have 2 'case' statements, like in the rules
5390          * below, and backup a single character (not spacing over the extend
5391          * ones) and then see if that is one of the region-end characters and
5392          * go from there */
5393         case WB_Ex_or_FO_or_ZWJ_then_foo:
5394             prev = backup_one_WB(&previous, strbeg, &before_pos, utf8_target);
5395             goto redo;
5396 
5397         case WB_DQ_then_HL + WB_BREAKABLE:
5398         case WB_DQ_then_HL + WB_NOBREAK:
5399 
5400             /* WB7c  Hebrew_Letter Double_Quote  ×  Hebrew_Letter */
5401 
5402             if (backup_one_WB(&previous, strbeg, &before_pos, utf8_target)
5403                                                             == WB_Hebrew_Letter)
5404             {
5405                 return FALSE;
5406             }
5407 
5408              return WB_table[before][after] - WB_DQ_then_HL == WB_BREAKABLE;
5409 
5410         case WB_HL_then_DQ + WB_BREAKABLE:
5411         case WB_HL_then_DQ + WB_NOBREAK:
5412 
5413             /* WB7b  Hebrew_Letter  ×  Double_Quote Hebrew_Letter */
5414 
5415             if (advance_one_WB(&after_pos, strend, utf8_target,
5416                                        TRUE /* Do skip Extend and Format */ )
5417                                                             == WB_Hebrew_Letter)
5418             {
5419                 return FALSE;
5420             }
5421 
5422             return WB_table[before][after] - WB_HL_then_DQ == WB_BREAKABLE;
5423 
5424         case WB_LE_or_HL_then_MB_or_ML_or_SQ + WB_NOBREAK:
5425         case WB_LE_or_HL_then_MB_or_ML_or_SQ + WB_BREAKABLE:
5426 
5427             /* WB6  (ALetter | Hebrew_Letter)  ×  (MidLetter | MidNumLet
5428              *       | Single_Quote) (ALetter | Hebrew_Letter) */
5429 
5430             next = advance_one_WB(&after_pos, strend, utf8_target,
5431                                        TRUE /* Do skip Extend and Format */ );
5432 
5433             if (next == WB_ALetter || next == WB_Hebrew_Letter)
5434             {
5435                 return FALSE;
5436             }
5437 
5438             return WB_table[before][after]
5439                             - WB_LE_or_HL_then_MB_or_ML_or_SQ == WB_BREAKABLE;
5440 
5441         case WB_MB_or_ML_or_SQ_then_LE_or_HL + WB_NOBREAK:
5442         case WB_MB_or_ML_or_SQ_then_LE_or_HL + WB_BREAKABLE:
5443 
5444             /* WB7  (ALetter | Hebrew_Letter) (MidLetter | MidNumLet
5445              *       | Single_Quote)  ×  (ALetter | Hebrew_Letter) */
5446 
5447             prev = backup_one_WB(&previous, strbeg, &before_pos, utf8_target);
5448             if (prev == WB_ALetter || prev == WB_Hebrew_Letter)
5449             {
5450                 return FALSE;
5451             }
5452 
5453             return WB_table[before][after]
5454                             - WB_MB_or_ML_or_SQ_then_LE_or_HL == WB_BREAKABLE;
5455 
5456         case WB_MB_or_MN_or_SQ_then_NU + WB_NOBREAK:
5457         case WB_MB_or_MN_or_SQ_then_NU + WB_BREAKABLE:
5458 
5459             /* WB11  Numeric (MidNum | (MidNumLet | Single_Quote))  ×  Numeric
5460              * */
5461 
5462             if (backup_one_WB(&previous, strbeg, &before_pos, utf8_target)
5463                                                             == WB_Numeric)
5464             {
5465                 return FALSE;
5466             }
5467 
5468             return WB_table[before][after]
5469                                 - WB_MB_or_MN_or_SQ_then_NU == WB_BREAKABLE;
5470 
5471         case WB_NU_then_MB_or_MN_or_SQ + WB_NOBREAK:
5472         case WB_NU_then_MB_or_MN_or_SQ + WB_BREAKABLE:
5473 
5474             /* WB12  Numeric  ×  (MidNum | MidNumLet | Single_Quote) Numeric */
5475 
5476             if (advance_one_WB(&after_pos, strend, utf8_target,
5477                                        TRUE /* Do skip Extend and Format */ )
5478                                                             == WB_Numeric)
5479             {
5480                 return FALSE;
5481             }
5482 
5483             return WB_table[before][after]
5484                                 - WB_NU_then_MB_or_MN_or_SQ == WB_BREAKABLE;
5485 
5486         case WB_RI_then_RI + WB_NOBREAK:
5487         case WB_RI_then_RI + WB_BREAKABLE:
5488             {
5489                 int RI_count = 1;
5490 
5491                 /* Do not break within emoji flag sequences. That is, do not
5492                  * break between regional indicator (RI) symbols if there is an
5493                  * odd number of RI characters before the potential break
5494                  * point.
5495                  *
5496                  * WB15   sot (RI RI)* RI × RI
5497                  * WB16 [^RI] (RI RI)* RI × RI */
5498 
5499                 while (backup_one_WB(&previous,
5500                                      strbeg,
5501                                      &before_pos,
5502                                      utf8_target) == WB_Regional_Indicator)
5503                 {
5504                     RI_count++;
5505                 }
5506 
5507                 return RI_count % 2 != 1;
5508             }
5509 
5510         default:
5511             break;
5512     }
5513 
5514 #ifdef DEBUGGING
5515     Perl_re_printf( aTHX_  "Unhandled WB pair: WB_table[%d, %d] = %d\n",
5516                                   before, after, WB_table[before][after]);
5517     assert(0);
5518 #endif
5519     return TRUE;
5520 }
5521 
5522 STATIC WB_enum
5523 S_advance_one_WB(pTHX_ U8 ** curpos,
5524                        const U8 * const strend,
5525                        const bool utf8_target,
5526                        const bool skip_Extend_Format)
5527 {
5528     WB_enum wb;
5529 
5530     PERL_ARGS_ASSERT_ADVANCE_ONE_WB;
5531 
5532     if (*curpos >= strend) {
5533         return WB_EDGE;
5534     }
5535 
5536     if (utf8_target) {
5537 
5538         /* Advance over Extend and Format */
5539         do {
5540             *curpos += UTF8SKIP(*curpos);
5541             if (*curpos >= strend) {
5542                 return WB_EDGE;
5543             }
5544             wb = getWB_VAL_UTF8(*curpos, strend);
5545         } while (    skip_Extend_Format
5546                  && (wb == WB_Extend || wb == WB_Format));
5547     }
5548     else {
5549         do {
5550             (*curpos)++;
5551             if (*curpos >= strend) {
5552                 return WB_EDGE;
5553             }
5554             wb = getWB_VAL_CP(**curpos);
5555         } while (    skip_Extend_Format
5556                  && (wb == WB_Extend || wb == WB_Format));
5557     }
5558 
5559     return wb;
5560 }
5561 
5562 STATIC WB_enum
5563 S_backup_one_WB(pTHX_ WB_enum * previous, const U8 * const strbeg, U8 ** curpos, const bool utf8_target)
5564 {
5565     WB_enum wb;
5566 
5567     PERL_ARGS_ASSERT_BACKUP_ONE_WB;
5568 
5569     /* If we know what the previous character's break value is, don't have
5570         * to look it up */
5571     if (*previous != WB_UNKNOWN) {
5572         wb = *previous;
5573 
5574         /* But we need to move backwards by one */
5575         if (utf8_target) {
5576             *curpos = reghopmaybe3(*curpos, -1, strbeg);
5577             if (! *curpos) {
5578                 *previous = WB_EDGE;
5579                 *curpos = (U8 *) strbeg;
5580             }
5581             else {
5582                 *previous = WB_UNKNOWN;
5583             }
5584         }
5585         else {
5586             (*curpos)--;
5587             *previous = (*curpos <= strbeg) ? WB_EDGE : WB_UNKNOWN;
5588         }
5589 
5590         /* And we always back up over these three types */
5591         if (wb != WB_Extend && wb != WB_Format && wb != WB_ZWJ) {
5592             return wb;
5593         }
5594     }
5595 
5596     if (*curpos < strbeg) {
5597         return WB_EDGE;
5598     }
5599 
5600     if (utf8_target) {
5601         U8 * prev_char_pos = reghopmaybe3(*curpos, -1, strbeg);
5602         if (! prev_char_pos) {
5603             return WB_EDGE;
5604         }
5605 
5606         /* Back up over Extend and Format.  curpos is always just to the right
5607          * of the characater whose value we are getting */
5608         do {
5609             U8 * prev_prev_char_pos;
5610             if ((prev_prev_char_pos = reghopmaybe3((U8 *) prev_char_pos,
5611                                                    -1,
5612                                                    strbeg)))
5613             {
5614                 wb = getWB_VAL_UTF8(prev_prev_char_pos, prev_char_pos);
5615                 *curpos = prev_char_pos;
5616                 prev_char_pos = prev_prev_char_pos;
5617             }
5618             else {
5619                 *curpos = (U8 *) strbeg;
5620                 return WB_EDGE;
5621             }
5622         } while (wb == WB_Extend || wb == WB_Format || wb == WB_ZWJ);
5623     }
5624     else {
5625         do {
5626             if (*curpos - 2 < strbeg) {
5627                 *curpos = (U8 *) strbeg;
5628                 return WB_EDGE;
5629             }
5630             (*curpos)--;
5631             wb = getWB_VAL_CP(*(*curpos - 1));
5632         } while (wb == WB_Extend || wb == WB_Format);
5633     }
5634 
5635     return wb;
5636 }
5637 
5638 #define EVAL_CLOSE_PAREN_IS(st,expr)                        \
5639 (                                                           \
5640     (   ( st )                                         ) && \
5641     (   ( st )->u.eval.close_paren                     ) && \
5642     ( ( ( st )->u.eval.close_paren ) == ( (expr) + 1 ) )    \
5643 )
5644 
5645 #define EVAL_CLOSE_PAREN_IS_TRUE(st,expr)                   \
5646 (                                                           \
5647     (   ( st )                                         ) && \
5648     (   ( st )->u.eval.close_paren                     ) && \
5649     (   ( expr )                                       ) && \
5650     ( ( ( st )->u.eval.close_paren ) == ( (expr) + 1 ) )    \
5651 )
5652 
5653 
5654 #define EVAL_CLOSE_PAREN_SET(st,expr) \
5655     (st)->u.eval.close_paren = ( (expr) + 1 )
5656 
5657 #define EVAL_CLOSE_PAREN_CLEAR(st) \
5658     (st)->u.eval.close_paren = 0
5659 
5660 /* returns -1 on failure, $+[0] on success */
5661 STATIC SSize_t
5662 S_regmatch(pTHX_ regmatch_info *reginfo, char *startpos, regnode *prog)
5663 {
5664     dVAR;
5665     const bool utf8_target = reginfo->is_utf8_target;
5666     const U32 uniflags = UTF8_ALLOW_DEFAULT;
5667     REGEXP *rex_sv = reginfo->prog;
5668     regexp *rex = ReANY(rex_sv);
5669     RXi_GET_DECL(rex,rexi);
5670     /* the current state. This is a cached copy of PL_regmatch_state */
5671     regmatch_state *st;
5672     /* cache heavy used fields of st in registers */
5673     regnode *scan;
5674     regnode *next;
5675     U32 n = 0;	/* general value; init to avoid compiler warning */
5676     SSize_t ln = 0; /* len or last;  init to avoid compiler warning */
5677     SSize_t endref = 0; /* offset of end of backref when ln is start */
5678     char *locinput = startpos;
5679     char *pushinput; /* where to continue after a PUSH */
5680     I32 nextchr;   /* is always set to UCHARAT(locinput), or -1 at EOS */
5681 
5682     bool result = 0;	    /* return value of S_regmatch */
5683     U32 depth = 0;            /* depth of backtrack stack */
5684     U32 nochange_depth = 0; /* depth of GOSUB recursion with nochange */
5685     const U32 max_nochange_depth =
5686         (3 * rex->nparens > MAX_RECURSE_EVAL_NOCHANGE_DEPTH) ?
5687         3 * rex->nparens : MAX_RECURSE_EVAL_NOCHANGE_DEPTH;
5688     regmatch_state *yes_state = NULL; /* state to pop to on success of
5689 							    subpattern */
5690     /* mark_state piggy backs on the yes_state logic so that when we unwind
5691        the stack on success we can update the mark_state as we go */
5692     regmatch_state *mark_state = NULL; /* last mark state we have seen */
5693     regmatch_state *cur_eval = NULL; /* most recent EVAL_AB state */
5694     struct regmatch_state  *cur_curlyx = NULL; /* most recent curlyx */
5695     U32 state_num;
5696     bool no_final = 0;      /* prevent failure from backtracking? */
5697     bool do_cutgroup = 0;   /* no_final only until next branch/trie entry */
5698     char *startpoint = locinput;
5699     SV *popmark = NULL;     /* are we looking for a mark? */
5700     SV *sv_commit = NULL;   /* last mark name seen in failure */
5701     SV *sv_yes_mark = NULL; /* last mark name we have seen
5702                                during a successful match */
5703     U32 lastopen = 0;       /* last open we saw */
5704     bool has_cutgroup = RXp_HAS_CUTGROUP(rex) ? 1 : 0;
5705     SV* const oreplsv = GvSVn(PL_replgv);
5706     /* these three flags are set by various ops to signal information to
5707      * the very next op. They have a useful lifetime of exactly one loop
5708      * iteration, and are not preserved or restored by state pushes/pops
5709      */
5710     bool sw = 0;	    /* the condition value in (?(cond)a|b) */
5711     bool minmod = 0;	    /* the next "{n,m}" is a "{n,m}?" */
5712     int logical = 0;	    /* the following EVAL is:
5713 				0: (?{...})
5714 				1: (?(?{...})X|Y)
5715 				2: (??{...})
5716 			       or the following IFMATCH/UNLESSM is:
5717 			        false: plain (?=foo)
5718 				true:  used as a condition: (?(?=foo))
5719 			    */
5720     PAD* last_pad = NULL;
5721     dMULTICALL;
5722     U8 gimme = G_SCALAR;
5723     CV *caller_cv = NULL;	/* who called us */
5724     CV *last_pushed_cv = NULL;	/* most recently called (?{}) CV */
5725     U32 maxopenparen = 0;       /* max '(' index seen so far */
5726     int to_complement;  /* Invert the result? */
5727     _char_class_number classnum;
5728     bool is_utf8_pat = reginfo->is_utf8_pat;
5729     bool match = FALSE;
5730     I32 orig_savestack_ix = PL_savestack_ix;
5731     U8 * script_run_begin = NULL;
5732 
5733 /* Solaris Studio 12.3 messes up fetching PL_charclass['\n'] */
5734 #if (defined(__SUNPRO_C) && (__SUNPRO_C == 0x5120) && defined(__x86_64) && defined(USE_64_BIT_ALL))
5735 #  define SOLARIS_BAD_OPTIMIZER
5736     const U32 *pl_charclass_dup = PL_charclass;
5737 #  define PL_charclass pl_charclass_dup
5738 #endif
5739 
5740 #ifdef DEBUGGING
5741     GET_RE_DEBUG_FLAGS_DECL;
5742 #endif
5743 
5744     /* protect against undef(*^R) */
5745     SAVEFREESV(SvREFCNT_inc_simple_NN(oreplsv));
5746 
5747     /* shut up 'may be used uninitialized' compiler warnings for dMULTICALL */
5748     multicall_oldcatch = 0;
5749     PERL_UNUSED_VAR(multicall_cop);
5750 
5751     PERL_ARGS_ASSERT_REGMATCH;
5752 
5753     st = PL_regmatch_state;
5754 
5755     /* Note that nextchr is a byte even in UTF */
5756     SET_nextchr;
5757     scan = prog;
5758 
5759     DEBUG_OPTIMISE_r( DEBUG_EXECUTE_r({
5760             DUMP_EXEC_POS( locinput, scan, utf8_target, depth );
5761             Perl_re_printf( aTHX_ "regmatch start\n" );
5762     }));
5763 
5764     while (scan != NULL) {
5765 	next = scan + NEXT_OFF(scan);
5766 	if (next == scan)
5767 	    next = NULL;
5768 	state_num = OP(scan);
5769 
5770       reenter_switch:
5771         DEBUG_EXECUTE_r(
5772             if (state_num <= REGNODE_MAX) {
5773                 SV * const prop = sv_newmortal();
5774                 regnode *rnext = regnext(scan);
5775 
5776                 DUMP_EXEC_POS( locinput, scan, utf8_target, depth );
5777                 regprop(rex, prop, scan, reginfo, NULL);
5778                 Perl_re_printf( aTHX_
5779                     "%*s%" IVdf ":%s(%" IVdf ")\n",
5780                     INDENT_CHARS(depth), "",
5781                     (IV)(scan - rexi->program),
5782                     SvPVX_const(prop),
5783                     (PL_regkind[OP(scan)] == END || !rnext) ?
5784                         0 : (IV)(rnext - rexi->program));
5785             }
5786         );
5787 
5788         to_complement = 0;
5789 
5790         SET_nextchr;
5791         assert(nextchr < 256 && (nextchr >= 0 || nextchr == NEXTCHR_EOS));
5792 
5793 	switch (state_num) {
5794 	case SBOL: /*  /^../ and /\A../  */
5795 	    if (locinput == reginfo->strbeg)
5796 		break;
5797 	    sayNO;
5798 
5799 	case MBOL: /*  /^../m  */
5800 	    if (locinput == reginfo->strbeg ||
5801 		(!NEXTCHR_IS_EOS && locinput[-1] == '\n'))
5802 	    {
5803 		break;
5804 	    }
5805 	    sayNO;
5806 
5807 	case GPOS: /*  \G  */
5808 	    if (locinput == reginfo->ganch)
5809 		break;
5810 	    sayNO;
5811 
5812 	case KEEPS: /*   \K  */
5813 	    /* update the startpoint */
5814 	    st->u.keeper.val = rex->offs[0].start;
5815 	    rex->offs[0].start = locinput - reginfo->strbeg;
5816 	    PUSH_STATE_GOTO(KEEPS_next, next, locinput);
5817 	    NOT_REACHED; /* NOTREACHED */
5818 
5819 	case KEEPS_next_fail:
5820 	    /* rollback the start point change */
5821 	    rex->offs[0].start = st->u.keeper.val;
5822 	    sayNO_SILENT;
5823 	    NOT_REACHED; /* NOTREACHED */
5824 
5825 	case MEOL: /* /..$/m  */
5826 	    if (!NEXTCHR_IS_EOS && nextchr != '\n')
5827 		sayNO;
5828 	    break;
5829 
5830 	case SEOL: /* /..$/  */
5831 	    if (!NEXTCHR_IS_EOS && nextchr != '\n')
5832 		sayNO;
5833 	    if (reginfo->strend - locinput > 1)
5834 		sayNO;
5835 	    break;
5836 
5837 	case EOS: /*  \z  */
5838 	    if (!NEXTCHR_IS_EOS)
5839 		sayNO;
5840 	    break;
5841 
5842 	case SANY: /*  /./s  */
5843 	    if (NEXTCHR_IS_EOS)
5844 		sayNO;
5845             goto increment_locinput;
5846 
5847 	case REG_ANY: /*  /./  */
5848 	    if ((NEXTCHR_IS_EOS) || nextchr == '\n')
5849 		sayNO;
5850             goto increment_locinput;
5851 
5852 
5853 #undef  ST
5854 #define ST st->u.trie
5855         case TRIEC: /* (ab|cd) with known charclass */
5856             /* In this case the charclass data is available inline so
5857                we can fail fast without a lot of extra overhead.
5858              */
5859             if(!NEXTCHR_IS_EOS && !ANYOF_BITMAP_TEST(scan, nextchr)) {
5860                 DEBUG_EXECUTE_r(
5861                     Perl_re_exec_indentf( aTHX_  "%sTRIE: failed to match trie start class...%s\n",
5862                               depth, PL_colors[4], PL_colors[5])
5863                 );
5864                 sayNO_SILENT;
5865                 NOT_REACHED; /* NOTREACHED */
5866             }
5867             /* FALLTHROUGH */
5868 	case TRIE:  /* (ab|cd)  */
5869 	    /* the basic plan of execution of the trie is:
5870 	     * At the beginning, run though all the states, and
5871 	     * find the longest-matching word. Also remember the position
5872 	     * of the shortest matching word. For example, this pattern:
5873 	     *    1  2 3 4    5
5874 	     *    ab|a|x|abcd|abc
5875 	     * when matched against the string "abcde", will generate
5876 	     * accept states for all words except 3, with the longest
5877 	     * matching word being 4, and the shortest being 2 (with
5878 	     * the position being after char 1 of the string).
5879 	     *
5880 	     * Then for each matching word, in word order (i.e. 1,2,4,5),
5881 	     * we run the remainder of the pattern; on each try setting
5882 	     * the current position to the character following the word,
5883 	     * returning to try the next word on failure.
5884 	     *
5885 	     * We avoid having to build a list of words at runtime by
5886 	     * using a compile-time structure, wordinfo[].prev, which
5887 	     * gives, for each word, the previous accepting word (if any).
5888 	     * In the case above it would contain the mappings 1->2, 2->0,
5889 	     * 3->0, 4->5, 5->1.  We can use this table to generate, from
5890 	     * the longest word (4 above), a list of all words, by
5891 	     * following the list of prev pointers; this gives us the
5892 	     * unordered list 4,5,1,2. Then given the current word we have
5893 	     * just tried, we can go through the list and find the
5894 	     * next-biggest word to try (so if we just failed on word 2,
5895 	     * the next in the list is 4).
5896 	     *
5897 	     * Since at runtime we don't record the matching position in
5898 	     * the string for each word, we have to work that out for
5899 	     * each word we're about to process. The wordinfo table holds
5900 	     * the character length of each word; given that we recorded
5901 	     * at the start: the position of the shortest word and its
5902 	     * length in chars, we just need to move the pointer the
5903 	     * difference between the two char lengths. Depending on
5904 	     * Unicode status and folding, that's cheap or expensive.
5905 	     *
5906 	     * This algorithm is optimised for the case where are only a
5907 	     * small number of accept states, i.e. 0,1, or maybe 2.
5908 	     * With lots of accepts states, and having to try all of them,
5909 	     * it becomes quadratic on number of accept states to find all
5910 	     * the next words.
5911 	     */
5912 
5913 	    {
5914                 /* what type of TRIE am I? (utf8 makes this contextual) */
5915                 DECL_TRIE_TYPE(scan);
5916 
5917                 /* what trie are we using right now */
5918 		reg_trie_data * const trie
5919         	    = (reg_trie_data*)rexi->data->data[ ARG( scan ) ];
5920 		HV * widecharmap = MUTABLE_HV(rexi->data->data[ ARG( scan ) + 1 ]);
5921                 U32 state = trie->startstate;
5922 
5923                 if (scan->flags == EXACTL || scan->flags == EXACTFLU8) {
5924                     _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
5925                     if (utf8_target
5926                         && ! NEXTCHR_IS_EOS
5927                         && UTF8_IS_ABOVE_LATIN1(nextchr)
5928                         && scan->flags == EXACTL)
5929                     {
5930                         /* We only output for EXACTL, as we let the folder
5931                          * output this message for EXACTFLU8 to avoid
5932                          * duplication */
5933                         _CHECK_AND_OUTPUT_WIDE_LOCALE_UTF8_MSG(locinput,
5934                                                                reginfo->strend);
5935                     }
5936                 }
5937                 if (   trie->bitmap
5938                     && (NEXTCHR_IS_EOS || !TRIE_BITMAP_TEST(trie, nextchr)))
5939                 {
5940         	    if (trie->states[ state ].wordnum) {
5941         	         DEBUG_EXECUTE_r(
5942                             Perl_re_exec_indentf( aTHX_  "%sTRIE: matched empty string...%s\n",
5943                                           depth, PL_colors[4], PL_colors[5])
5944                         );
5945 			if (!trie->jump)
5946 			    break;
5947         	    } else {
5948         	        DEBUG_EXECUTE_r(
5949                             Perl_re_exec_indentf( aTHX_  "%sTRIE: failed to match trie start class...%s\n",
5950                                           depth, PL_colors[4], PL_colors[5])
5951                         );
5952         	        sayNO_SILENT;
5953         	   }
5954                 }
5955 
5956             {
5957 		U8 *uc = ( U8* )locinput;
5958 
5959 		STRLEN len = 0;
5960 		STRLEN foldlen = 0;
5961 		U8 *uscan = (U8*)NULL;
5962 		U8 foldbuf[ UTF8_MAXBYTES_CASE + 1 ];
5963 		U32 charcount = 0; /* how many input chars we have matched */
5964 		U32 accepted = 0; /* have we seen any accepting states? */
5965 
5966 		ST.jump = trie->jump;
5967 		ST.me = scan;
5968 		ST.firstpos = NULL;
5969 		ST.longfold = FALSE; /* char longer if folded => it's harder */
5970 		ST.nextword = 0;
5971 
5972 		/* fully traverse the TRIE; note the position of the
5973 		   shortest accept state and the wordnum of the longest
5974 		   accept state */
5975 
5976 		while ( state && uc <= (U8*)(reginfo->strend) ) {
5977                     U32 base = trie->states[ state ].trans.base;
5978                     UV uvc = 0;
5979                     U16 charid = 0;
5980 		    U16 wordnum;
5981                     wordnum = trie->states[ state ].wordnum;
5982 
5983 		    if (wordnum) { /* it's an accept state */
5984 			if (!accepted) {
5985 			    accepted = 1;
5986 			    /* record first match position */
5987 			    if (ST.longfold) {
5988 				ST.firstpos = (U8*)locinput;
5989 				ST.firstchars = 0;
5990 			    }
5991 			    else {
5992 				ST.firstpos = uc;
5993 				ST.firstchars = charcount;
5994 			    }
5995 			}
5996 			if (!ST.nextword || wordnum < ST.nextword)
5997 			    ST.nextword = wordnum;
5998 			ST.topword = wordnum;
5999 		    }
6000 
6001 		    DEBUG_TRIE_EXECUTE_r({
6002                                 DUMP_EXEC_POS( (char *)uc, scan, utf8_target, depth );
6003                                 /* HERE */
6004                                 PerlIO_printf( Perl_debug_log,
6005                                     "%*s%sTRIE: State: %4" UVxf " Accepted: %c ",
6006                                     INDENT_CHARS(depth), "", PL_colors[4],
6007 			            (UV)state, (accepted ? 'Y' : 'N'));
6008 		    });
6009 
6010 		    /* read a char and goto next state */
6011 		    if ( base && (foldlen || uc < (U8*)(reginfo->strend))) {
6012 			I32 offset;
6013 			REXEC_TRIE_READ_CHAR(trie_type, trie, widecharmap, uc,
6014                                              (U8 *) reginfo->strend, uscan,
6015                                              len, uvc, charid, foldlen,
6016                                              foldbuf, uniflags);
6017 			charcount++;
6018 			if (foldlen>0)
6019 			    ST.longfold = TRUE;
6020 			if (charid &&
6021 			     ( ((offset =
6022 			      base + charid - 1 - trie->uniquecharcount)) >= 0)
6023 
6024 			     && ((U32)offset < trie->lasttrans)
6025 			     && trie->trans[offset].check == state)
6026 			{
6027 			    state = trie->trans[offset].next;
6028 			}
6029 			else {
6030 			    state = 0;
6031 			}
6032 			uc += len;
6033 
6034 		    }
6035 		    else {
6036 			state = 0;
6037 		    }
6038 		    DEBUG_TRIE_EXECUTE_r(
6039                         Perl_re_printf( aTHX_
6040 		            "TRIE: Charid:%3x CP:%4" UVxf " After State: %4" UVxf "%s\n",
6041 		            charid, uvc, (UV)state, PL_colors[5] );
6042 		    );
6043 		}
6044 		if (!accepted)
6045 		   sayNO;
6046 
6047 		/* calculate total number of accept states */
6048 		{
6049 		    U16 w = ST.topword;
6050 		    accepted = 0;
6051 		    while (w) {
6052 			w = trie->wordinfo[w].prev;
6053 			accepted++;
6054 		    }
6055 		    ST.accepted = accepted;
6056 		}
6057 
6058 		DEBUG_EXECUTE_r(
6059                     Perl_re_exec_indentf( aTHX_  "%sTRIE: got %" IVdf " possible matches%s\n",
6060                         depth,
6061 			PL_colors[4], (IV)ST.accepted, PL_colors[5] );
6062 		);
6063 		goto trie_first_try; /* jump into the fail handler */
6064 	    }}
6065 	    NOT_REACHED; /* NOTREACHED */
6066 
6067 	case TRIE_next_fail: /* we failed - try next alternative */
6068         {
6069             U8 *uc;
6070             if ( ST.jump ) {
6071                 /* undo any captures done in the tail part of a branch,
6072                  * e.g.
6073                  *    /(?:X(.)(.)|Y(.)).../
6074                  * where the trie just matches X then calls out to do the
6075                  * rest of the branch */
6076                 REGCP_UNWIND(ST.cp);
6077                 UNWIND_PAREN(ST.lastparen, ST.lastcloseparen);
6078 	    }
6079 	    if (!--ST.accepted) {
6080 	        DEBUG_EXECUTE_r({
6081                     Perl_re_exec_indentf( aTHX_  "%sTRIE failed...%s\n",
6082                         depth,
6083 			PL_colors[4],
6084 			PL_colors[5] );
6085 		});
6086 		sayNO_SILENT;
6087 	    }
6088 	    {
6089 		/* Find next-highest word to process.  Note that this code
6090 		 * is O(N^2) per trie run (O(N) per branch), so keep tight */
6091 		U16 min = 0;
6092 		U16 word;
6093 		U16 const nextword = ST.nextword;
6094 		reg_trie_wordinfo * const wordinfo
6095 		    = ((reg_trie_data*)rexi->data->data[ARG(ST.me)])->wordinfo;
6096 		for (word=ST.topword; word; word=wordinfo[word].prev) {
6097 		    if (word > nextword && (!min || word < min))
6098 			min = word;
6099 		}
6100 		ST.nextword = min;
6101 	    }
6102 
6103           trie_first_try:
6104             if (do_cutgroup) {
6105                 do_cutgroup = 0;
6106                 no_final = 0;
6107             }
6108 
6109             if ( ST.jump ) {
6110                 ST.lastparen = rex->lastparen;
6111                 ST.lastcloseparen = rex->lastcloseparen;
6112 	        REGCP_SET(ST.cp);
6113             }
6114 
6115 	    /* find start char of end of current word */
6116 	    {
6117 		U32 chars; /* how many chars to skip */
6118 		reg_trie_data * const trie
6119 		    = (reg_trie_data*)rexi->data->data[ARG(ST.me)];
6120 
6121 		assert((trie->wordinfo[ST.nextword].len - trie->prefixlen)
6122 			    >=  ST.firstchars);
6123 		chars = (trie->wordinfo[ST.nextword].len - trie->prefixlen)
6124 			    - ST.firstchars;
6125 		uc = ST.firstpos;
6126 
6127 		if (ST.longfold) {
6128 		    /* the hard option - fold each char in turn and find
6129 		     * its folded length (which may be different */
6130 		    U8 foldbuf[UTF8_MAXBYTES_CASE + 1];
6131 		    STRLEN foldlen;
6132 		    STRLEN len;
6133 		    UV uvc;
6134 		    U8 *uscan;
6135 
6136 		    while (chars) {
6137 			if (utf8_target) {
6138 			    uvc = utf8n_to_uvchr((U8*)uc, UTF8_MAXLEN, &len,
6139 						    uniflags);
6140 			    uc += len;
6141 			}
6142 			else {
6143 			    uvc = *uc;
6144 			    uc++;
6145 			}
6146 			uvc = to_uni_fold(uvc, foldbuf, &foldlen);
6147 			uscan = foldbuf;
6148 			while (foldlen) {
6149 			    if (!--chars)
6150 				break;
6151 			    uvc = utf8n_to_uvchr(uscan, foldlen, &len,
6152                                                  uniflags);
6153 			    uscan += len;
6154 			    foldlen -= len;
6155 			}
6156 		    }
6157 		}
6158 		else {
6159 		    if (utf8_target)
6160 			while (chars--)
6161 			    uc += UTF8SKIP(uc);
6162 		    else
6163 			uc += chars;
6164 		}
6165 	    }
6166 
6167 	    scan = ST.me + ((ST.jump && ST.jump[ST.nextword])
6168 			    ? ST.jump[ST.nextword]
6169 			    : NEXT_OFF(ST.me));
6170 
6171 	    DEBUG_EXECUTE_r({
6172                 Perl_re_exec_indentf( aTHX_  "%sTRIE matched word #%d, continuing%s\n",
6173                     depth,
6174 		    PL_colors[4],
6175 		    ST.nextword,
6176 		    PL_colors[5]
6177 		    );
6178 	    });
6179 
6180 	    if ( ST.accepted > 1 || has_cutgroup || ST.jump ) {
6181 		PUSH_STATE_GOTO(TRIE_next, scan, (char*)uc);
6182 		NOT_REACHED; /* NOTREACHED */
6183 	    }
6184 	    /* only one choice left - just continue */
6185 	    DEBUG_EXECUTE_r({
6186 		AV *const trie_words
6187 		    = MUTABLE_AV(rexi->data->data[ARG(ST.me)+TRIE_WORDS_OFFSET]);
6188 		SV ** const tmp = trie_words
6189                         ? av_fetch(trie_words, ST.nextword - 1, 0) : NULL;
6190 		SV *sv= tmp ? sv_newmortal() : NULL;
6191 
6192                 Perl_re_exec_indentf( aTHX_  "%sTRIE: only one match left, short-circuiting: #%d <%s>%s\n",
6193                     depth, PL_colors[4],
6194 		    ST.nextword,
6195 		    tmp ? pv_pretty(sv, SvPV_nolen_const(*tmp), SvCUR(*tmp), 0,
6196 			    PL_colors[0], PL_colors[1],
6197 			    (SvUTF8(*tmp) ? PERL_PV_ESCAPE_UNI : 0)|PERL_PV_ESCAPE_NONASCII
6198 			)
6199 		    : "not compiled under -Dr",
6200 		    PL_colors[5] );
6201 	    });
6202 
6203 	    locinput = (char*)uc;
6204 	    continue; /* execute rest of RE */
6205             /* NOTREACHED */
6206         }
6207 #undef  ST
6208 
6209 	case EXACTL:             /*  /abc/l       */
6210             _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
6211 
6212             /* Complete checking would involve going through every character
6213              * matched by the string to see if any is above latin1.  But the
6214              * comparision otherwise might very well be a fast assembly
6215              * language routine, and I (khw) don't think slowing things down
6216              * just to check for this warning is worth it.  So this just checks
6217              * the first character */
6218             if (utf8_target && UTF8_IS_ABOVE_LATIN1(*locinput)) {
6219                 _CHECK_AND_OUTPUT_WIDE_LOCALE_UTF8_MSG(locinput, reginfo->strend);
6220             }
6221             /* FALLTHROUGH */
6222 	case EXACT: {            /*  /abc/        */
6223 	    char *s = STRING(scan);
6224 	    ln = STR_LEN(scan);
6225 	    if (utf8_target != is_utf8_pat) {
6226 		/* The target and the pattern have differing utf8ness. */
6227 		char *l = locinput;
6228 		const char * const e = s + ln;
6229 
6230 		if (utf8_target) {
6231                     /* The target is utf8, the pattern is not utf8.
6232                      * Above-Latin1 code points can't match the pattern;
6233                      * invariants match exactly, and the other Latin1 ones need
6234                      * to be downgraded to a single byte in order to do the
6235                      * comparison.  (If we could be confident that the target
6236                      * is not malformed, this could be refactored to have fewer
6237                      * tests by just assuming that if the first bytes match, it
6238                      * is an invariant, but there are tests in the test suite
6239                      * dealing with (??{...}) which violate this) */
6240 		    while (s < e) {
6241 			if (l >= reginfo->strend
6242                             || UTF8_IS_ABOVE_LATIN1(* (U8*) l))
6243                         {
6244                             sayNO;
6245                         }
6246                         if (UTF8_IS_INVARIANT(*(U8*)l)) {
6247 			    if (*l != *s) {
6248                                 sayNO;
6249                             }
6250                             l++;
6251                         }
6252                         else {
6253                             if (EIGHT_BIT_UTF8_TO_NATIVE(*l, *(l+1)) != * (U8*) s)
6254                             {
6255                                 sayNO;
6256                             }
6257                             l += 2;
6258                         }
6259 			s++;
6260 		    }
6261 		}
6262 		else {
6263 		    /* The target is not utf8, the pattern is utf8. */
6264 		    while (s < e) {
6265                         if (l >= reginfo->strend
6266                             || UTF8_IS_ABOVE_LATIN1(* (U8*) s))
6267                         {
6268                             sayNO;
6269                         }
6270                         if (UTF8_IS_INVARIANT(*(U8*)s)) {
6271 			    if (*s != *l) {
6272                                 sayNO;
6273                             }
6274                             s++;
6275                         }
6276                         else {
6277                             if (EIGHT_BIT_UTF8_TO_NATIVE(*s, *(s+1)) != * (U8*) l)
6278                             {
6279                                 sayNO;
6280                             }
6281                             s += 2;
6282                         }
6283 			l++;
6284 		    }
6285 		}
6286 		locinput = l;
6287 	    }
6288             else {
6289                 /* The target and the pattern have the same utf8ness. */
6290                 /* Inline the first character, for speed. */
6291                 if (reginfo->strend - locinput < ln
6292                     || UCHARAT(s) != nextchr
6293                     || (ln > 1 && memNE(s, locinput, ln)))
6294                 {
6295                     sayNO;
6296                 }
6297                 locinput += ln;
6298             }
6299 	    break;
6300 	    }
6301 
6302 	case EXACTFL: {          /*  /abc/il      */
6303 	    re_fold_t folder;
6304 	    const U8 * fold_array;
6305 	    const char * s;
6306 	    U32 fold_utf8_flags;
6307 
6308             _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
6309             folder = foldEQ_locale;
6310             fold_array = PL_fold_locale;
6311 	    fold_utf8_flags = FOLDEQ_LOCALE;
6312 	    goto do_exactf;
6313 
6314         case EXACTFLU8:           /*  /abc/il; but all 'abc' are above 255, so
6315                                       is effectively /u; hence to match, target
6316                                       must be UTF-8. */
6317             if (! utf8_target) {
6318                 sayNO;
6319             }
6320             fold_utf8_flags =  FOLDEQ_LOCALE | FOLDEQ_S1_ALREADY_FOLDED
6321                                              | FOLDEQ_S1_FOLDS_SANE;
6322 	    folder = foldEQ_latin1;
6323 	    fold_array = PL_fold_latin1;
6324 	    goto do_exactf;
6325 
6326 	case EXACTFU_SS:         /*  /\x{df}/iu   */
6327 	case EXACTFU:            /*  /abc/iu      */
6328 	    folder = foldEQ_latin1;
6329 	    fold_array = PL_fold_latin1;
6330 	    fold_utf8_flags = is_utf8_pat ? FOLDEQ_S1_ALREADY_FOLDED : 0;
6331 	    goto do_exactf;
6332 
6333         case EXACTFAA_NO_TRIE:   /* This node only generated for non-utf8
6334                                    patterns */
6335             assert(! is_utf8_pat);
6336             /* FALLTHROUGH */
6337 	case EXACTFAA:            /*  /abc/iaa     */
6338 	    folder = foldEQ_latin1;
6339 	    fold_array = PL_fold_latin1;
6340 	    fold_utf8_flags = FOLDEQ_UTF8_NOMIX_ASCII;
6341 	    goto do_exactf;
6342 
6343         case EXACTF:             /*  /abc/i    This node only generated for
6344                                                non-utf8 patterns */
6345             assert(! is_utf8_pat);
6346 	    folder = foldEQ;
6347 	    fold_array = PL_fold;
6348 	    fold_utf8_flags = 0;
6349 
6350 	  do_exactf:
6351 	    s = STRING(scan);
6352 	    ln = STR_LEN(scan);
6353 
6354 	    if (utf8_target
6355                 || is_utf8_pat
6356                 || state_num == EXACTFU_SS
6357                 || (state_num == EXACTFL && IN_UTF8_CTYPE_LOCALE))
6358             {
6359 	      /* Either target or the pattern are utf8, or has the issue where
6360 	       * the fold lengths may differ. */
6361 		const char * const l = locinput;
6362 		char *e = reginfo->strend;
6363 
6364 		if (! foldEQ_utf8_flags(s, 0,  ln, is_utf8_pat,
6365 			                l, &e, 0,  utf8_target, fold_utf8_flags))
6366 		{
6367 		    sayNO;
6368 		}
6369 		locinput = e;
6370 		break;
6371 	    }
6372 
6373 	    /* Neither the target nor the pattern are utf8 */
6374 	    if (UCHARAT(s) != nextchr
6375                 && !NEXTCHR_IS_EOS
6376 		&& UCHARAT(s) != fold_array[nextchr])
6377 	    {
6378 		sayNO;
6379 	    }
6380 	    if (reginfo->strend - locinput < ln)
6381 		sayNO;
6382 	    if (ln > 1 && ! folder(s, locinput, ln))
6383 		sayNO;
6384 	    locinput += ln;
6385 	    break;
6386 	}
6387 
6388 	case NBOUNDL: /*  /\B/l  */
6389             to_complement = 1;
6390             /* FALLTHROUGH */
6391 
6392 	case BOUNDL:  /*  /\b/l  */
6393         {
6394             bool b1, b2;
6395             _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
6396 
6397             if (FLAGS(scan) != TRADITIONAL_BOUND) {
6398                 if (! IN_UTF8_CTYPE_LOCALE) {
6399                     Perl_ck_warner(aTHX_ packWARN(WARN_LOCALE),
6400                                                 B_ON_NON_UTF8_LOCALE_IS_WRONG);
6401                 }
6402                 goto boundu;
6403             }
6404 
6405 	    if (utf8_target) {
6406 		if (locinput == reginfo->strbeg)
6407 		    b1 = isWORDCHAR_LC('\n');
6408 		else {
6409                     b1 = isWORDCHAR_LC_utf8_safe(reghop3((U8*)locinput, -1,
6410                                                         (U8*)(reginfo->strbeg)),
6411                                                  (U8*)(reginfo->strend));
6412 		}
6413                 b2 = (NEXTCHR_IS_EOS)
6414                     ? isWORDCHAR_LC('\n')
6415                     : isWORDCHAR_LC_utf8_safe((U8*) locinput,
6416                                               (U8*) reginfo->strend);
6417 	    }
6418 	    else { /* Here the string isn't utf8 */
6419 		b1 = (locinput == reginfo->strbeg)
6420                      ? isWORDCHAR_LC('\n')
6421                      : isWORDCHAR_LC(UCHARAT(locinput - 1));
6422                 b2 = (NEXTCHR_IS_EOS)
6423                     ? isWORDCHAR_LC('\n')
6424                     : isWORDCHAR_LC(nextchr);
6425 	    }
6426             if (to_complement ^ (b1 == b2)) {
6427                 sayNO;
6428             }
6429 	    break;
6430         }
6431 
6432 	case NBOUND:  /*  /\B/   */
6433             to_complement = 1;
6434             /* FALLTHROUGH */
6435 
6436 	case BOUND:   /*  /\b/   */
6437 	    if (utf8_target) {
6438                 goto bound_utf8;
6439             }
6440             goto bound_ascii_match_only;
6441 
6442 	case NBOUNDA: /*  /\B/a  */
6443             to_complement = 1;
6444             /* FALLTHROUGH */
6445 
6446 	case BOUNDA:  /*  /\b/a  */
6447         {
6448             bool b1, b2;
6449 
6450           bound_ascii_match_only:
6451             /* Here the string isn't utf8, or is utf8 and only ascii characters
6452              * are to match \w.  In the latter case looking at the byte just
6453              * prior to the current one may be just the final byte of a
6454              * multi-byte character.  This is ok.  There are two cases:
6455              * 1) it is a single byte character, and then the test is doing
6456              *    just what it's supposed to.
6457              * 2) it is a multi-byte character, in which case the final byte is
6458              *    never mistakable for ASCII, and so the test will say it is
6459              *    not a word character, which is the correct answer. */
6460             b1 = (locinput == reginfo->strbeg)
6461                  ? isWORDCHAR_A('\n')
6462                  : isWORDCHAR_A(UCHARAT(locinput - 1));
6463             b2 = (NEXTCHR_IS_EOS)
6464                 ? isWORDCHAR_A('\n')
6465                 : isWORDCHAR_A(nextchr);
6466             if (to_complement ^ (b1 == b2)) {
6467                 sayNO;
6468             }
6469 	    break;
6470         }
6471 
6472 	case NBOUNDU: /*  /\B/u  */
6473             to_complement = 1;
6474             /* FALLTHROUGH */
6475 
6476 	case BOUNDU:  /*  /\b/u  */
6477 
6478           boundu:
6479             if (UNLIKELY(reginfo->strbeg >= reginfo->strend)) {
6480                 match = FALSE;
6481             }
6482             else if (utf8_target) {
6483               bound_utf8:
6484                 switch((bound_type) FLAGS(scan)) {
6485                     case TRADITIONAL_BOUND:
6486                     {
6487                         bool b1, b2;
6488                         b1 = (locinput == reginfo->strbeg)
6489                              ? 0 /* isWORDCHAR_L1('\n') */
6490                              : isWORDCHAR_utf8_safe(
6491                                                reghop3((U8*)locinput,
6492                                                        -1,
6493                                                        (U8*)(reginfo->strbeg)),
6494                                                     (U8*) reginfo->strend);
6495                         b2 = (NEXTCHR_IS_EOS)
6496                             ? 0 /* isWORDCHAR_L1('\n') */
6497                             : isWORDCHAR_utf8_safe((U8*)locinput,
6498                                                    (U8*) reginfo->strend);
6499                         match = cBOOL(b1 != b2);
6500                         break;
6501                     }
6502                     case GCB_BOUND:
6503                         if (locinput == reginfo->strbeg || NEXTCHR_IS_EOS) {
6504                             match = TRUE; /* GCB always matches at begin and
6505                                              end */
6506                         }
6507                         else {
6508                             /* Find the gcb values of previous and current
6509                              * chars, then see if is a break point */
6510                             match = isGCB(getGCB_VAL_UTF8(
6511                                                 reghop3((U8*)locinput,
6512                                                         -1,
6513                                                         (U8*)(reginfo->strbeg)),
6514                                                 (U8*) reginfo->strend),
6515                                           getGCB_VAL_UTF8((U8*) locinput,
6516                                                         (U8*) reginfo->strend),
6517                                           (U8*) reginfo->strbeg,
6518                                           (U8*) locinput,
6519                                           utf8_target);
6520                         }
6521                         break;
6522 
6523                     case LB_BOUND:
6524                         if (locinput == reginfo->strbeg) {
6525                             match = FALSE;
6526                         }
6527                         else if (NEXTCHR_IS_EOS) {
6528                             match = TRUE;
6529                         }
6530                         else {
6531                             match = isLB(getLB_VAL_UTF8(
6532                                                 reghop3((U8*)locinput,
6533                                                         -1,
6534                                                         (U8*)(reginfo->strbeg)),
6535                                                 (U8*) reginfo->strend),
6536                                           getLB_VAL_UTF8((U8*) locinput,
6537                                                         (U8*) reginfo->strend),
6538                                           (U8*) reginfo->strbeg,
6539                                           (U8*) locinput,
6540                                           (U8*) reginfo->strend,
6541                                           utf8_target);
6542                         }
6543                         break;
6544 
6545                     case SB_BOUND: /* Always matches at begin and end */
6546                         if (locinput == reginfo->strbeg || NEXTCHR_IS_EOS) {
6547                             match = TRUE;
6548                         }
6549                         else {
6550                             match = isSB(getSB_VAL_UTF8(
6551                                                 reghop3((U8*)locinput,
6552                                                         -1,
6553                                                         (U8*)(reginfo->strbeg)),
6554                                                 (U8*) reginfo->strend),
6555                                           getSB_VAL_UTF8((U8*) locinput,
6556                                                         (U8*) reginfo->strend),
6557                                           (U8*) reginfo->strbeg,
6558                                           (U8*) locinput,
6559                                           (U8*) reginfo->strend,
6560                                           utf8_target);
6561                         }
6562                         break;
6563 
6564                     case WB_BOUND:
6565                         if (locinput == reginfo->strbeg || NEXTCHR_IS_EOS) {
6566                             match = TRUE;
6567                         }
6568                         else {
6569                             match = isWB(WB_UNKNOWN,
6570                                          getWB_VAL_UTF8(
6571                                                 reghop3((U8*)locinput,
6572                                                         -1,
6573                                                         (U8*)(reginfo->strbeg)),
6574                                                 (U8*) reginfo->strend),
6575                                           getWB_VAL_UTF8((U8*) locinput,
6576                                                         (U8*) reginfo->strend),
6577                                           (U8*) reginfo->strbeg,
6578                                           (U8*) locinput,
6579                                           (U8*) reginfo->strend,
6580                                           utf8_target);
6581                         }
6582                         break;
6583                 }
6584 	    }
6585 	    else {  /* Not utf8 target */
6586                 switch((bound_type) FLAGS(scan)) {
6587                     case TRADITIONAL_BOUND:
6588                     {
6589                         bool b1, b2;
6590                         b1 = (locinput == reginfo->strbeg)
6591                             ? 0 /* isWORDCHAR_L1('\n') */
6592                             : isWORDCHAR_L1(UCHARAT(locinput - 1));
6593                         b2 = (NEXTCHR_IS_EOS)
6594                             ? 0 /* isWORDCHAR_L1('\n') */
6595                             : isWORDCHAR_L1(nextchr);
6596                         match = cBOOL(b1 != b2);
6597                         break;
6598                     }
6599 
6600                     case GCB_BOUND:
6601                         if (locinput == reginfo->strbeg || NEXTCHR_IS_EOS) {
6602                             match = TRUE; /* GCB always matches at begin and
6603                                              end */
6604                         }
6605                         else {  /* Only CR-LF combo isn't a GCB in 0-255
6606                                    range */
6607                             match =    UCHARAT(locinput - 1) != '\r'
6608                                     || UCHARAT(locinput) != '\n';
6609                         }
6610                         break;
6611 
6612                     case LB_BOUND:
6613                         if (locinput == reginfo->strbeg) {
6614                             match = FALSE;
6615                         }
6616                         else if (NEXTCHR_IS_EOS) {
6617                             match = TRUE;
6618                         }
6619                         else {
6620                             match = isLB(getLB_VAL_CP(UCHARAT(locinput -1)),
6621                                          getLB_VAL_CP(UCHARAT(locinput)),
6622                                          (U8*) reginfo->strbeg,
6623                                          (U8*) locinput,
6624                                          (U8*) reginfo->strend,
6625                                          utf8_target);
6626                         }
6627                         break;
6628 
6629                     case SB_BOUND: /* Always matches at begin and end */
6630                         if (locinput == reginfo->strbeg || NEXTCHR_IS_EOS) {
6631                             match = TRUE;
6632                         }
6633                         else {
6634                             match = isSB(getSB_VAL_CP(UCHARAT(locinput -1)),
6635                                          getSB_VAL_CP(UCHARAT(locinput)),
6636                                          (U8*) reginfo->strbeg,
6637                                          (U8*) locinput,
6638                                          (U8*) reginfo->strend,
6639                                          utf8_target);
6640                         }
6641                         break;
6642 
6643                     case WB_BOUND:
6644                         if (locinput == reginfo->strbeg || NEXTCHR_IS_EOS) {
6645                             match = TRUE;
6646                         }
6647                         else {
6648                             match = isWB(WB_UNKNOWN,
6649                                          getWB_VAL_CP(UCHARAT(locinput -1)),
6650                                          getWB_VAL_CP(UCHARAT(locinput)),
6651                                          (U8*) reginfo->strbeg,
6652                                          (U8*) locinput,
6653                                          (U8*) reginfo->strend,
6654                                          utf8_target);
6655                         }
6656                         break;
6657                 }
6658 	    }
6659 
6660             if (to_complement ^ ! match) {
6661                 sayNO;
6662             }
6663 	    break;
6664 
6665 	case ANYOFL:  /*  /[abc]/l      */
6666             _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
6667 
6668             if (ANYOFL_UTF8_LOCALE_REQD(FLAGS(scan)) && ! IN_UTF8_CTYPE_LOCALE)
6669             {
6670               Perl_ck_warner(aTHX_ packWARN(WARN_LOCALE), utf8_locale_required);
6671             }
6672             /* FALLTHROUGH */
6673 	case ANYOFD:  /*   /[abc]/d       */
6674 	case ANYOF:  /*   /[abc]/       */
6675             if (NEXTCHR_IS_EOS)
6676                 sayNO;
6677 	    if (utf8_target && ! UTF8_IS_INVARIANT(*locinput)) {
6678 	        if (!reginclass(rex, scan, (U8*)locinput, (U8*)reginfo->strend,
6679                                                                    utf8_target))
6680 		    sayNO;
6681 		locinput += UTF8SKIP(locinput);
6682 	    }
6683 	    else {
6684 		if (!REGINCLASS(rex, scan, (U8*)locinput, utf8_target))
6685 		    sayNO;
6686 		locinput++;
6687 	    }
6688 	    break;
6689 
6690         case ANYOFM:
6691             if (NEXTCHR_IS_EOS || (UCHARAT(locinput) & FLAGS(scan)) != ARG(scan)) {
6692                 sayNO;
6693             }
6694             locinput++;
6695             break;
6696 
6697         case ASCII:
6698             if (NEXTCHR_IS_EOS || ! isASCII(UCHARAT(locinput))) {
6699                 sayNO;
6700             }
6701 
6702             locinput++;     /* ASCII is always single byte */
6703             break;
6704 
6705         case NASCII:
6706             if (NEXTCHR_IS_EOS || isASCII(UCHARAT(locinput))) {
6707                 sayNO;
6708             }
6709 
6710             goto increment_locinput;
6711             break;
6712 
6713         /* The argument (FLAGS) to all the POSIX node types is the class number
6714          * */
6715 
6716         case NPOSIXL:   /* \W or [:^punct:] etc. under /l */
6717             to_complement = 1;
6718             /* FALLTHROUGH */
6719 
6720         case POSIXL:    /* \w or [:punct:] etc. under /l */
6721             _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
6722             if (NEXTCHR_IS_EOS)
6723                 sayNO;
6724 
6725             /* Use isFOO_lc() for characters within Latin1.  (Note that
6726              * UTF8_IS_INVARIANT works even on non-UTF-8 strings, or else
6727              * wouldn't be invariant) */
6728             if (UTF8_IS_INVARIANT(nextchr) || ! utf8_target) {
6729                 if (! (to_complement ^ cBOOL(isFOO_lc(FLAGS(scan), (U8) nextchr)))) {
6730                     sayNO;
6731                 }
6732 
6733                 locinput++;
6734                 break;
6735             }
6736 
6737             if (! UTF8_IS_NEXT_CHAR_DOWNGRADEABLE(locinput, reginfo->strend)) {
6738                 /* An above Latin-1 code point, or malformed */
6739                 _CHECK_AND_OUTPUT_WIDE_LOCALE_UTF8_MSG(locinput,
6740                                                        reginfo->strend);
6741                 goto utf8_posix_above_latin1;
6742             }
6743 
6744             /* Here is a UTF-8 variant code point below 256 and the target is
6745              * UTF-8 */
6746             if (! (to_complement ^ cBOOL(isFOO_lc(FLAGS(scan),
6747                                             EIGHT_BIT_UTF8_TO_NATIVE(nextchr,
6748                                             *(locinput + 1))))))
6749             {
6750                 sayNO;
6751             }
6752 
6753             goto increment_locinput;
6754 
6755         case NPOSIXD:   /* \W or [:^punct:] etc. under /d */
6756             to_complement = 1;
6757             /* FALLTHROUGH */
6758 
6759         case POSIXD:    /* \w or [:punct:] etc. under /d */
6760             if (utf8_target) {
6761                 goto utf8_posix;
6762             }
6763             goto posixa;
6764 
6765         case NPOSIXA:   /* \W or [:^punct:] etc. under /a */
6766 
6767             if (NEXTCHR_IS_EOS) {
6768                 sayNO;
6769             }
6770 
6771             /* All UTF-8 variants match */
6772             if (! UTF8_IS_INVARIANT(nextchr)) {
6773                 goto increment_locinput;
6774             }
6775 
6776             to_complement = 1;
6777             goto join_nposixa;
6778 
6779         case POSIXA:    /* \w or [:punct:] etc. under /a */
6780 
6781           posixa:
6782             /* We get here through POSIXD, NPOSIXD, and NPOSIXA when not in
6783              * UTF-8, and also from NPOSIXA even in UTF-8 when the current
6784              * character is a single byte */
6785 
6786             if (NEXTCHR_IS_EOS) {
6787                 sayNO;
6788             }
6789 
6790           join_nposixa:
6791 
6792             if (! (to_complement ^ cBOOL(_generic_isCC_A(nextchr,
6793                                                                 FLAGS(scan)))))
6794             {
6795                 sayNO;
6796             }
6797 
6798             /* Here we are either not in utf8, or we matched a utf8-invariant,
6799              * so the next char is the next byte */
6800             locinput++;
6801             break;
6802 
6803         case NPOSIXU:   /* \W or [:^punct:] etc. under /u */
6804             to_complement = 1;
6805             /* FALLTHROUGH */
6806 
6807         case POSIXU:    /* \w or [:punct:] etc. under /u */
6808           utf8_posix:
6809             if (NEXTCHR_IS_EOS) {
6810                 sayNO;
6811             }
6812 
6813             /* Use _generic_isCC() for characters within Latin1.  (Note that
6814              * UTF8_IS_INVARIANT works even on non-UTF-8 strings, or else
6815              * wouldn't be invariant) */
6816             if (UTF8_IS_INVARIANT(nextchr) || ! utf8_target) {
6817                 if (! (to_complement ^ cBOOL(_generic_isCC(nextchr,
6818                                                            FLAGS(scan)))))
6819                 {
6820                     sayNO;
6821                 }
6822                 locinput++;
6823             }
6824             else if (UTF8_IS_NEXT_CHAR_DOWNGRADEABLE(locinput, reginfo->strend)) {
6825                 if (! (to_complement
6826                        ^ cBOOL(_generic_isCC(EIGHT_BIT_UTF8_TO_NATIVE(nextchr,
6827                                                                *(locinput + 1)),
6828                                              FLAGS(scan)))))
6829                 {
6830                     sayNO;
6831                 }
6832                 locinput += 2;
6833             }
6834             else {  /* Handle above Latin-1 code points */
6835               utf8_posix_above_latin1:
6836                 classnum = (_char_class_number) FLAGS(scan);
6837                 switch (classnum) {
6838                     default:
6839                         if (! (to_complement
6840                            ^ cBOOL(_invlist_contains_cp(
6841                                       PL_XPosix_ptrs[classnum],
6842                                       utf8_to_uvchr_buf((U8 *) locinput,
6843                                                         (U8 *) reginfo->strend,
6844                                                         NULL)))))
6845                         {
6846                             sayNO;
6847                         }
6848                         break;
6849                     case _CC_ENUM_SPACE:
6850                         if (! (to_complement
6851                                     ^ cBOOL(is_XPERLSPACE_high(locinput))))
6852                         {
6853                             sayNO;
6854                         }
6855                         break;
6856                     case _CC_ENUM_BLANK:
6857                         if (! (to_complement
6858                                         ^ cBOOL(is_HORIZWS_high(locinput))))
6859                         {
6860                             sayNO;
6861                         }
6862                         break;
6863                     case _CC_ENUM_XDIGIT:
6864                         if (! (to_complement
6865                                         ^ cBOOL(is_XDIGIT_high(locinput))))
6866                         {
6867                             sayNO;
6868                         }
6869                         break;
6870                     case _CC_ENUM_VERTSPACE:
6871                         if (! (to_complement
6872                                         ^ cBOOL(is_VERTWS_high(locinput))))
6873                         {
6874                             sayNO;
6875                         }
6876                         break;
6877                     case _CC_ENUM_CNTRL:    /* These can't match above Latin1 */
6878                     case _CC_ENUM_ASCII:
6879                         if (! to_complement) {
6880                             sayNO;
6881                         }
6882                         break;
6883                 }
6884                 locinput += UTF8SKIP(locinput);
6885             }
6886             break;
6887 
6888 	case CLUMP: /* Match \X: logical Unicode character.  This is defined as
6889 		       a Unicode extended Grapheme Cluster */
6890 	    if (NEXTCHR_IS_EOS)
6891 		sayNO;
6892 	    if  (! utf8_target) {
6893 
6894 		/* Match either CR LF  or '.', as all the other possibilities
6895 		 * require utf8 */
6896 		locinput++;	    /* Match the . or CR */
6897 		if (nextchr == '\r' /* And if it was CR, and the next is LF,
6898 				       match the LF */
6899 		    && locinput < reginfo->strend
6900 		    && UCHARAT(locinput) == '\n')
6901                 {
6902                     locinput++;
6903                 }
6904 	    }
6905 	    else {
6906 
6907                 /* Get the gcb type for the current character */
6908                 GCB_enum prev_gcb = getGCB_VAL_UTF8((U8*) locinput,
6909                                                        (U8*) reginfo->strend);
6910 
6911                 /* Then scan through the input until we get to the first
6912                  * character whose type is supposed to be a gcb with the
6913                  * current character.  (There is always a break at the
6914                  * end-of-input) */
6915                 locinput += UTF8SKIP(locinput);
6916                 while (locinput < reginfo->strend) {
6917                     GCB_enum cur_gcb = getGCB_VAL_UTF8((U8*) locinput,
6918                                                          (U8*) reginfo->strend);
6919                     if (isGCB(prev_gcb, cur_gcb,
6920                               (U8*) reginfo->strbeg, (U8*) locinput,
6921                               utf8_target))
6922                     {
6923                         break;
6924                     }
6925 
6926                     prev_gcb = cur_gcb;
6927                     locinput += UTF8SKIP(locinput);
6928                 }
6929 
6930 
6931 	    }
6932 	    break;
6933 
6934 	case NREFFL:  /*  /\g{name}/il  */
6935 	{   /* The capture buffer cases.  The ones beginning with N for the
6936 	       named buffers just convert to the equivalent numbered and
6937 	       pretend they were called as the corresponding numbered buffer
6938 	       op.  */
6939 	    /* don't initialize these in the declaration, it makes C++
6940 	       unhappy */
6941 	    const char *s;
6942 	    char type;
6943 	    re_fold_t folder;
6944 	    const U8 *fold_array;
6945 	    UV utf8_fold_flags;
6946 
6947             _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
6948 	    folder = foldEQ_locale;
6949 	    fold_array = PL_fold_locale;
6950 	    type = REFFL;
6951 	    utf8_fold_flags = FOLDEQ_LOCALE;
6952 	    goto do_nref;
6953 
6954 	case NREFFA:  /*  /\g{name}/iaa  */
6955 	    folder = foldEQ_latin1;
6956 	    fold_array = PL_fold_latin1;
6957 	    type = REFFA;
6958 	    utf8_fold_flags = FOLDEQ_UTF8_NOMIX_ASCII;
6959 	    goto do_nref;
6960 
6961 	case NREFFU:  /*  /\g{name}/iu  */
6962 	    folder = foldEQ_latin1;
6963 	    fold_array = PL_fold_latin1;
6964 	    type = REFFU;
6965 	    utf8_fold_flags = 0;
6966 	    goto do_nref;
6967 
6968 	case NREFF:  /*  /\g{name}/i  */
6969 	    folder = foldEQ;
6970 	    fold_array = PL_fold;
6971 	    type = REFF;
6972 	    utf8_fold_flags = 0;
6973 	    goto do_nref;
6974 
6975 	case NREF:  /*  /\g{name}/   */
6976 	    type = REF;
6977 	    folder = NULL;
6978 	    fold_array = NULL;
6979 	    utf8_fold_flags = 0;
6980 	  do_nref:
6981 
6982 	    /* For the named back references, find the corresponding buffer
6983 	     * number */
6984 	    n = reg_check_named_buff_matched(rex,scan);
6985 
6986             if ( ! n ) {
6987                 sayNO;
6988 	    }
6989 	    goto do_nref_ref_common;
6990 
6991 	case REFFL:  /*  /\1/il  */
6992             _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
6993 	    folder = foldEQ_locale;
6994 	    fold_array = PL_fold_locale;
6995 	    utf8_fold_flags = FOLDEQ_LOCALE;
6996 	    goto do_ref;
6997 
6998 	case REFFA:  /*  /\1/iaa  */
6999 	    folder = foldEQ_latin1;
7000 	    fold_array = PL_fold_latin1;
7001 	    utf8_fold_flags = FOLDEQ_UTF8_NOMIX_ASCII;
7002 	    goto do_ref;
7003 
7004 	case REFFU:  /*  /\1/iu  */
7005 	    folder = foldEQ_latin1;
7006 	    fold_array = PL_fold_latin1;
7007 	    utf8_fold_flags = 0;
7008 	    goto do_ref;
7009 
7010 	case REFF:  /*  /\1/i  */
7011 	    folder = foldEQ;
7012 	    fold_array = PL_fold;
7013 	    utf8_fold_flags = 0;
7014 	    goto do_ref;
7015 
7016         case REF:  /*  /\1/    */
7017 	    folder = NULL;
7018 	    fold_array = NULL;
7019 	    utf8_fold_flags = 0;
7020 
7021 	  do_ref:
7022 	    type = OP(scan);
7023 	    n = ARG(scan);  /* which paren pair */
7024 
7025 	  do_nref_ref_common:
7026 	    ln = rex->offs[n].start;
7027 	    endref = rex->offs[n].end;
7028 	    reginfo->poscache_iter = reginfo->poscache_maxiter; /* Void cache */
7029 	    if (rex->lastparen < n || ln == -1 || endref == -1)
7030 		sayNO;			/* Do not match unless seen CLOSEn. */
7031 	    if (ln == endref)
7032 		break;
7033 
7034 	    s = reginfo->strbeg + ln;
7035 	    if (type != REF	/* REF can do byte comparison */
7036 		&& (utf8_target || type == REFFU || type == REFFL))
7037 	    {
7038 		char * limit = reginfo->strend;
7039 
7040 		/* This call case insensitively compares the entire buffer
7041 		    * at s, with the current input starting at locinput, but
7042                     * not going off the end given by reginfo->strend, and
7043                     * returns in <limit> upon success, how much of the
7044                     * current input was matched */
7045 		if (! foldEQ_utf8_flags(s, NULL, endref - ln, utf8_target,
7046 				    locinput, &limit, 0, utf8_target, utf8_fold_flags))
7047 		{
7048 		    sayNO;
7049 		}
7050 		locinput = limit;
7051 		break;
7052 	    }
7053 
7054 	    /* Not utf8:  Inline the first character, for speed. */
7055 	    if (!NEXTCHR_IS_EOS &&
7056                 UCHARAT(s) != nextchr &&
7057 		(type == REF ||
7058 		 UCHARAT(s) != fold_array[nextchr]))
7059 		sayNO;
7060 	    ln = endref - ln;
7061 	    if (locinput + ln > reginfo->strend)
7062 		sayNO;
7063 	    if (ln > 1 && (type == REF
7064 			   ? memNE(s, locinput, ln)
7065 			   : ! folder(s, locinput, ln)))
7066 		sayNO;
7067 	    locinput += ln;
7068 	    break;
7069 	}
7070 
7071 	case NOTHING: /* null op; e.g. the 'nothing' following
7072                        * the '*' in m{(a+|b)*}' */
7073 	    break;
7074 	case TAIL: /* placeholder while compiling (A|B|C) */
7075 	    break;
7076 
7077 #undef  ST
7078 #define ST st->u.eval
7079 #define CUR_EVAL cur_eval->u.eval
7080 
7081 	{
7082 	    SV *ret;
7083 	    REGEXP *re_sv;
7084             regexp *re;
7085             regexp_internal *rei;
7086             regnode *startpoint;
7087             U32 arg;
7088 
7089 	case GOSUB: /*    /(...(?1))/   /(...(?&foo))/   */
7090             arg= (U32)ARG(scan);
7091             if (cur_eval && cur_eval->locinput == locinput) {
7092                 if ( ++nochange_depth > max_nochange_depth )
7093                     Perl_croak(aTHX_
7094                         "Pattern subroutine nesting without pos change"
7095                         " exceeded limit in regex");
7096             } else {
7097                 nochange_depth = 0;
7098             }
7099 	    re_sv = rex_sv;
7100             re = rex;
7101             rei = rexi;
7102             startpoint = scan + ARG2L(scan);
7103             EVAL_CLOSE_PAREN_SET( st, arg );
7104             /* Detect infinite recursion
7105              *
7106              * A pattern like /(?R)foo/ or /(?<x>(?&y)foo)(?<y>(?&x)bar)/
7107              * or "a"=~/(.(?2))((?<=(?=(?1)).))/ could recurse forever.
7108              * So we track the position in the string we are at each time
7109              * we recurse and if we try to enter the same routine twice from
7110              * the same position we throw an error.
7111              */
7112             if ( rex->recurse_locinput[arg] == locinput ) {
7113                 /* FIXME: we should show the regop that is failing as part
7114                  * of the error message. */
7115                 Perl_croak(aTHX_ "Infinite recursion in regex");
7116             } else {
7117                 ST.prev_recurse_locinput= rex->recurse_locinput[arg];
7118                 rex->recurse_locinput[arg]= locinput;
7119 
7120                 DEBUG_r({
7121                     GET_RE_DEBUG_FLAGS_DECL;
7122                     DEBUG_STACK_r({
7123                         Perl_re_exec_indentf( aTHX_
7124                             "entering GOSUB, prev_recurse_locinput=%p recurse_locinput[%d]=%p\n",
7125                             depth, ST.prev_recurse_locinput, arg, rex->recurse_locinput[arg]
7126                         );
7127                     });
7128                 });
7129             }
7130 
7131             /* Save all the positions seen so far. */
7132             ST.cp = regcppush(rex, 0, maxopenparen);
7133             REGCP_SET(ST.lastcp);
7134 
7135             /* and then jump to the code we share with EVAL */
7136             goto eval_recurse_doit;
7137             /* NOTREACHED */
7138 
7139         case EVAL:  /*   /(?{...})B/   /(??{A})B/  and  /(?(?{...})X|Y)B/   */
7140             if (cur_eval && cur_eval->locinput==locinput) {
7141 		if ( ++nochange_depth > max_nochange_depth )
7142                     Perl_croak(aTHX_ "EVAL without pos change exceeded limit in regex");
7143             } else {
7144                 nochange_depth = 0;
7145             }
7146 	    {
7147 		/* execute the code in the {...} */
7148 
7149 		dSP;
7150 		IV before;
7151 		OP * const oop = PL_op;
7152 		COP * const ocurcop = PL_curcop;
7153 		OP *nop;
7154 		CV *newcv;
7155 
7156 		/* save *all* paren positions */
7157                 regcppush(rex, 0, maxopenparen);
7158                 REGCP_SET(ST.lastcp);
7159 
7160 		if (!caller_cv)
7161 		    caller_cv = find_runcv(NULL);
7162 
7163 		n = ARG(scan);
7164 
7165 		if (rexi->data->what[n] == 'r') { /* code from an external qr */
7166                     newcv = (ReANY(
7167                                     (REGEXP*)(rexi->data->data[n])
7168                             ))->qr_anoncv;
7169 		    nop = (OP*)rexi->data->data[n+1];
7170 		}
7171 		else if (rexi->data->what[n] == 'l') { /* literal code */
7172 		    newcv = caller_cv;
7173 		    nop = (OP*)rexi->data->data[n];
7174 		    assert(CvDEPTH(newcv));
7175 		}
7176 		else {
7177 		    /* literal with own CV */
7178 		    assert(rexi->data->what[n] == 'L');
7179 		    newcv = rex->qr_anoncv;
7180 		    nop = (OP*)rexi->data->data[n];
7181 		}
7182 
7183                 /* Some notes about MULTICALL and the context and save stacks.
7184                  *
7185                  * In something like
7186                  *   /...(?{ my $x)}...(?{ my $y)}...(?{ my $z)}.../
7187                  * since codeblocks don't introduce a new scope (so that
7188                  * local() etc accumulate), at the end of a successful
7189                  * match there will be a SAVEt_CLEARSV on the savestack
7190                  * for each of $x, $y, $z. If the three code blocks above
7191                  * happen to have come from different CVs (e.g. via
7192                  * embedded qr//s), then we must ensure that during any
7193                  * savestack unwinding, PL_comppad always points to the
7194                  * right pad at each moment. We achieve this by
7195                  * interleaving SAVEt_COMPPAD's on the savestack whenever
7196                  * there is a change of pad.
7197                  * In theory whenever we call a code block, we should
7198                  * push a CXt_SUB context, then pop it on return from
7199                  * that code block. This causes a bit of an issue in that
7200                  * normally popping a context also clears the savestack
7201                  * back to cx->blk_oldsaveix, but here we specifically
7202                  * don't want to clear the save stack on exit from the
7203                  * code block.
7204                  * Also for efficiency we don't want to keep pushing and
7205                  * popping the single SUB context as we backtrack etc.
7206                  * So instead, we push a single context the first time
7207                  * we need, it, then hang onto it until the end of this
7208                  * function. Whenever we encounter a new code block, we
7209                  * update the CV etc if that's changed. During the times
7210                  * in this function where we're not executing a code
7211                  * block, having the SUB context still there is a bit
7212                  * naughty - but we hope that no-one notices.
7213                  * When the SUB context is initially pushed, we fake up
7214                  * cx->blk_oldsaveix to be as if we'd pushed this context
7215                  * on first entry to S_regmatch rather than at some random
7216                  * point during the regexe execution. That way if we
7217                  * croak, popping the context stack will ensure that
7218                  * *everything* SAVEd by this function is undone and then
7219                  * the context popped, rather than e.g., popping the
7220                  * context (and restoring the original PL_comppad) then
7221                  * popping more of the savestack and restoring a bad
7222                  * PL_comppad.
7223                  */
7224 
7225                 /* If this is the first EVAL, push a MULTICALL. On
7226                  * subsequent calls, if we're executing a different CV, or
7227                  * if PL_comppad has got messed up from backtracking
7228                  * through SAVECOMPPADs, then refresh the context.
7229                  */
7230 		if (newcv != last_pushed_cv || PL_comppad != last_pad)
7231 		{
7232                     U8 flags = (CXp_SUB_RE |
7233                                 ((newcv == caller_cv) ? CXp_SUB_RE_FAKE : 0));
7234                     SAVECOMPPAD();
7235 		    if (last_pushed_cv) {
7236 			CHANGE_MULTICALL_FLAGS(newcv, flags);
7237 		    }
7238 		    else {
7239 			PUSH_MULTICALL_FLAGS(newcv, flags);
7240 		    }
7241                     /* see notes above */
7242                     CX_CUR()->blk_oldsaveix = orig_savestack_ix;
7243 
7244 		    last_pushed_cv = newcv;
7245 		}
7246 		else {
7247                     /* these assignments are just to silence compiler
7248                      * warnings */
7249 		    multicall_cop = NULL;
7250 		}
7251 		last_pad = PL_comppad;
7252 
7253 		/* the initial nextstate you would normally execute
7254 		 * at the start of an eval (which would cause error
7255 		 * messages to come from the eval), may be optimised
7256 		 * away from the execution path in the regex code blocks;
7257 		 * so manually set PL_curcop to it initially */
7258 		{
7259 		    OP *o = cUNOPx(nop)->op_first;
7260 		    assert(o->op_type == OP_NULL);
7261 		    if (o->op_targ == OP_SCOPE) {
7262 			o = cUNOPo->op_first;
7263 		    }
7264 		    else {
7265 			assert(o->op_targ == OP_LEAVE);
7266 			o = cUNOPo->op_first;
7267 			assert(o->op_type == OP_ENTER);
7268 			o = OpSIBLING(o);
7269 		    }
7270 
7271 		    if (o->op_type != OP_STUB) {
7272 			assert(    o->op_type == OP_NEXTSTATE
7273 				|| o->op_type == OP_DBSTATE
7274 				|| (o->op_type == OP_NULL
7275 				    &&  (  o->op_targ == OP_NEXTSTATE
7276 					|| o->op_targ == OP_DBSTATE
7277 					)
7278 				    )
7279 			);
7280 			PL_curcop = (COP*)o;
7281 		    }
7282 		}
7283 		nop = nop->op_next;
7284 
7285                 DEBUG_STATE_r( Perl_re_printf( aTHX_
7286 		    "  re EVAL PL_op=0x%" UVxf "\n", PTR2UV(nop)) );
7287 
7288 		rex->offs[0].end = locinput - reginfo->strbeg;
7289                 if (reginfo->info_aux_eval->pos_magic)
7290                     MgBYTEPOS_set(reginfo->info_aux_eval->pos_magic,
7291                                   reginfo->sv, reginfo->strbeg,
7292                                   locinput - reginfo->strbeg);
7293 
7294                 if (sv_yes_mark) {
7295                     SV *sv_mrk = get_sv("REGMARK", 1);
7296                     sv_setsv(sv_mrk, sv_yes_mark);
7297                 }
7298 
7299 		/* we don't use MULTICALL here as we want to call the
7300 		 * first op of the block of interest, rather than the
7301 		 * first op of the sub. Also, we don't want to free
7302                  * the savestack frame */
7303 		before = (IV)(SP-PL_stack_base);
7304 		PL_op = nop;
7305 		CALLRUNOPS(aTHX);			/* Scalar context. */
7306 		SPAGAIN;
7307 		if ((IV)(SP-PL_stack_base) == before)
7308 		    ret = &PL_sv_undef;   /* protect against empty (?{}) blocks. */
7309 		else {
7310 		    ret = POPs;
7311 		    PUTBACK;
7312 		}
7313 
7314 		/* before restoring everything, evaluate the returned
7315 		 * value, so that 'uninit' warnings don't use the wrong
7316 		 * PL_op or pad. Also need to process any magic vars
7317 		 * (e.g. $1) *before* parentheses are restored */
7318 
7319 		PL_op = NULL;
7320 
7321                 re_sv = NULL;
7322 		if (logical == 0)        /*   (?{})/   */
7323 		    sv_setsv(save_scalar(PL_replgv), ret); /* $^R */
7324 		else if (logical == 1) { /*   /(?(?{...})X|Y)/    */
7325 		    sw = cBOOL(SvTRUE_NN(ret));
7326 		    logical = 0;
7327 		}
7328 		else {                   /*  /(??{})  */
7329 		    /*  if its overloaded, let the regex compiler handle
7330 		     *  it; otherwise extract regex, or stringify  */
7331 		    if (SvGMAGICAL(ret))
7332 			ret = sv_mortalcopy(ret);
7333 		    if (!SvAMAGIC(ret)) {
7334 			SV *sv = ret;
7335 			if (SvROK(sv))
7336 			    sv = SvRV(sv);
7337 			if (SvTYPE(sv) == SVt_REGEXP)
7338 			    re_sv = (REGEXP*) sv;
7339 			else if (SvSMAGICAL(ret)) {
7340 			    MAGIC *mg = mg_find(ret, PERL_MAGIC_qr);
7341 			    if (mg)
7342 				re_sv = (REGEXP *) mg->mg_obj;
7343 			}
7344 
7345 			/* force any undef warnings here */
7346 			if (!re_sv && !SvPOK(ret) && !SvNIOK(ret)) {
7347 			    ret = sv_mortalcopy(ret);
7348 			    (void) SvPV_force_nolen(ret);
7349 			}
7350 		    }
7351 
7352 		}
7353 
7354 		/* *** Note that at this point we don't restore
7355 		 * PL_comppad, (or pop the CxSUB) on the assumption it may
7356 		 * be used again soon. This is safe as long as nothing
7357 		 * in the regexp code uses the pad ! */
7358 		PL_op = oop;
7359 		PL_curcop = ocurcop;
7360                 regcp_restore(rex, ST.lastcp, &maxopenparen);
7361                 PL_curpm_under = PL_curpm;
7362                 PL_curpm = PL_reg_curpm;
7363 
7364 		if (logical != 2) {
7365                     PUSH_STATE_GOTO(EVAL_B, next, locinput);
7366 		    /* NOTREACHED */
7367                 }
7368 	    }
7369 
7370 		/* only /(??{})/  from now on */
7371 		logical = 0;
7372 		{
7373 		    /* extract RE object from returned value; compiling if
7374 		     * necessary */
7375 
7376 		    if (re_sv) {
7377 			re_sv = reg_temp_copy(NULL, re_sv);
7378 		    }
7379 		    else {
7380 			U32 pm_flags = 0;
7381 
7382 			if (SvUTF8(ret) && IN_BYTES) {
7383 			    /* In use 'bytes': make a copy of the octet
7384 			     * sequence, but without the flag on */
7385 			    STRLEN len;
7386 			    const char *const p = SvPV(ret, len);
7387 			    ret = newSVpvn_flags(p, len, SVs_TEMP);
7388 			}
7389 			if (rex->intflags & PREGf_USE_RE_EVAL)
7390 			    pm_flags |= PMf_USE_RE_EVAL;
7391 
7392 			/* if we got here, it should be an engine which
7393 			 * supports compiling code blocks and stuff */
7394 			assert(rex->engine && rex->engine->op_comp);
7395                         assert(!(scan->flags & ~RXf_PMf_COMPILETIME));
7396 			re_sv = rex->engine->op_comp(aTHX_ &ret, 1, NULL,
7397 				    rex->engine, NULL, NULL,
7398                                     /* copy /msixn etc to inner pattern */
7399                                     ARG2L(scan),
7400                                     pm_flags);
7401 
7402 			if (!(SvFLAGS(ret)
7403 			      & (SVs_TEMP | SVs_GMG | SVf_ROK))
7404 			 && (!SvPADTMP(ret) || SvREADONLY(ret))) {
7405 			    /* This isn't a first class regexp. Instead, it's
7406 			       caching a regexp onto an existing, Perl visible
7407 			       scalar.  */
7408 			    sv_magic(ret, MUTABLE_SV(re_sv), PERL_MAGIC_qr, 0, 0);
7409 			}
7410 		    }
7411 		    SAVEFREESV(re_sv);
7412 		    re = ReANY(re_sv);
7413 		}
7414                 RXp_MATCH_COPIED_off(re);
7415                 re->subbeg = rex->subbeg;
7416                 re->sublen = rex->sublen;
7417                 re->suboffset = rex->suboffset;
7418                 re->subcoffset = rex->subcoffset;
7419                 re->lastparen = 0;
7420                 re->lastcloseparen = 0;
7421 		rei = RXi_GET(re);
7422                 DEBUG_EXECUTE_r(
7423                     debug_start_match(re_sv, utf8_target, locinput,
7424                                     reginfo->strend, "EVAL/GOSUB: Matching embedded");
7425 		);
7426 		startpoint = rei->program + 1;
7427                 EVAL_CLOSE_PAREN_CLEAR(st); /* ST.close_paren = 0;
7428                                              * close_paren only for GOSUB */
7429                 ST.prev_recurse_locinput= NULL; /* only used for GOSUB */
7430                 /* Save all the seen positions so far. */
7431                 ST.cp = regcppush(rex, 0, maxopenparen);
7432                 REGCP_SET(ST.lastcp);
7433                 /* and set maxopenparen to 0, since we are starting a "fresh" match */
7434                 maxopenparen = 0;
7435                 /* run the pattern returned from (??{...}) */
7436 
7437               eval_recurse_doit: /* Share code with GOSUB below this line
7438                             * At this point we expect the stack context to be
7439                             * set up correctly */
7440 
7441                 /* invalidate the S-L poscache. We're now executing a
7442                  * different set of WHILEM ops (and their associated
7443                  * indexes) against the same string, so the bits in the
7444                  * cache are meaningless. Setting maxiter to zero forces
7445                  * the cache to be invalidated and zeroed before reuse.
7446 		 * XXX This is too dramatic a measure. Ideally we should
7447                  * save the old cache and restore when running the outer
7448                  * pattern again */
7449 		reginfo->poscache_maxiter = 0;
7450 
7451                 /* the new regexp might have a different is_utf8_pat than we do */
7452                 is_utf8_pat = reginfo->is_utf8_pat = cBOOL(RX_UTF8(re_sv));
7453 
7454 		ST.prev_rex = rex_sv;
7455 		ST.prev_curlyx = cur_curlyx;
7456 		rex_sv = re_sv;
7457 		SET_reg_curpm(rex_sv);
7458 		rex = re;
7459 		rexi = rei;
7460 		cur_curlyx = NULL;
7461 		ST.B = next;
7462 		ST.prev_eval = cur_eval;
7463 		cur_eval = st;
7464 		/* now continue from first node in postoned RE */
7465 		PUSH_YES_STATE_GOTO(EVAL_postponed_AB, startpoint, locinput);
7466 		NOT_REACHED; /* NOTREACHED */
7467 	}
7468 
7469 	case EVAL_postponed_AB: /* cleanup after a successful (??{A})B */
7470             /* note: this is called twice; first after popping B, then A */
7471             DEBUG_STACK_r({
7472                 Perl_re_exec_indentf( aTHX_  "EVAL_AB cur_eval=%p prev_eval=%p\n",
7473                     depth, cur_eval, ST.prev_eval);
7474             });
7475 
7476 #define SET_RECURSE_LOCINPUT(STR,VAL)\
7477             if ( cur_eval && CUR_EVAL.close_paren ) {\
7478                 DEBUG_STACK_r({ \
7479                     Perl_re_exec_indentf( aTHX_  STR " GOSUB%d ce=%p recurse_locinput=%p\n",\
7480                         depth,    \
7481                         CUR_EVAL.close_paren - 1,\
7482                         cur_eval, \
7483                         VAL);     \
7484                 });               \
7485                 rex->recurse_locinput[CUR_EVAL.close_paren - 1] = VAL;\
7486             }
7487 
7488             SET_RECURSE_LOCINPUT("EVAL_AB[before]", CUR_EVAL.prev_recurse_locinput);
7489 
7490 	    rex_sv = ST.prev_rex;
7491             is_utf8_pat = reginfo->is_utf8_pat = cBOOL(RX_UTF8(rex_sv));
7492 	    SET_reg_curpm(rex_sv);
7493 	    rex = ReANY(rex_sv);
7494 	    rexi = RXi_GET(rex);
7495             {
7496                 /* preserve $^R across LEAVE's. See Bug 121070. */
7497                 SV *save_sv= GvSV(PL_replgv);
7498                 SvREFCNT_inc(save_sv);
7499                 regcpblow(ST.cp); /* LEAVE in disguise */
7500                 sv_setsv(GvSV(PL_replgv), save_sv);
7501                 SvREFCNT_dec(save_sv);
7502             }
7503 	    cur_eval = ST.prev_eval;
7504 	    cur_curlyx = ST.prev_curlyx;
7505 
7506 	    /* Invalidate cache. See "invalidate" comment above. */
7507 	    reginfo->poscache_maxiter = 0;
7508             if ( nochange_depth )
7509 	        nochange_depth--;
7510 
7511             SET_RECURSE_LOCINPUT("EVAL_AB[after]", cur_eval->locinput);
7512 	    sayYES;
7513 
7514 
7515 	case EVAL_B_fail: /* unsuccessful B in (?{...})B */
7516 	    REGCP_UNWIND(ST.lastcp);
7517             sayNO;
7518 
7519 	case EVAL_postponed_AB_fail: /* unsuccessfully ran A or B in (??{A})B */
7520 	    /* note: this is called twice; first after popping B, then A */
7521             DEBUG_STACK_r({
7522                 Perl_re_exec_indentf( aTHX_  "EVAL_AB_fail cur_eval=%p prev_eval=%p\n",
7523                     depth, cur_eval, ST.prev_eval);
7524             });
7525 
7526             SET_RECURSE_LOCINPUT("EVAL_AB_fail[before]", CUR_EVAL.prev_recurse_locinput);
7527 
7528 	    rex_sv = ST.prev_rex;
7529             is_utf8_pat = reginfo->is_utf8_pat = cBOOL(RX_UTF8(rex_sv));
7530 	    SET_reg_curpm(rex_sv);
7531 	    rex = ReANY(rex_sv);
7532 	    rexi = RXi_GET(rex);
7533 
7534 	    REGCP_UNWIND(ST.lastcp);
7535             regcppop(rex, &maxopenparen);
7536 	    cur_eval = ST.prev_eval;
7537 	    cur_curlyx = ST.prev_curlyx;
7538 
7539 	    /* Invalidate cache. See "invalidate" comment above. */
7540 	    reginfo->poscache_maxiter = 0;
7541 	    if ( nochange_depth )
7542 	        nochange_depth--;
7543 
7544             SET_RECURSE_LOCINPUT("EVAL_AB_fail[after]", cur_eval->locinput);
7545             sayNO_SILENT;
7546 #undef ST
7547 
7548 	case OPEN: /*  (  */
7549 	    n = ARG(scan);  /* which paren pair */
7550 	    rex->offs[n].start_tmp = locinput - reginfo->strbeg;
7551 	    if (n > maxopenparen)
7552 		maxopenparen = n;
7553             DEBUG_BUFFERS_r(Perl_re_exec_indentf( aTHX_
7554 		"OPEN: rex=0x%" UVxf " offs=0x%" UVxf ": \\%" UVuf ": set %" IVdf " tmp; maxopenparen=%" UVuf "\n",
7555                 depth,
7556 		PTR2UV(rex),
7557 		PTR2UV(rex->offs),
7558 		(UV)n,
7559 		(IV)rex->offs[n].start_tmp,
7560 		(UV)maxopenparen
7561 	    ));
7562             lastopen = n;
7563 	    break;
7564 
7565         case SROPEN: /*  (*SCRIPT_RUN:  */
7566             script_run_begin = (U8 *) locinput;
7567             break;
7568 
7569 /* XXX really need to log other places start/end are set too */
7570 #define CLOSE_CAPTURE                                                      \
7571     rex->offs[n].start = rex->offs[n].start_tmp;                           \
7572     rex->offs[n].end = locinput - reginfo->strbeg;                         \
7573     DEBUG_BUFFERS_r(Perl_re_exec_indentf( aTHX_                            \
7574         "CLOSE: rex=0x%" UVxf " offs=0x%" UVxf ": \\%" UVuf ": set %" IVdf "..%" IVdf "\n", \
7575         depth,                                                             \
7576         PTR2UV(rex),                                                       \
7577         PTR2UV(rex->offs),                                                 \
7578         (UV)n,                                                             \
7579         (IV)rex->offs[n].start,                                            \
7580         (IV)rex->offs[n].end                                               \
7581     ))
7582 
7583 	case CLOSE:  /*  )  */
7584 	    n = ARG(scan);  /* which paren pair */
7585 	    CLOSE_CAPTURE;
7586 	    if (n > rex->lastparen)
7587 		rex->lastparen = n;
7588 	    rex->lastcloseparen = n;
7589             if ( EVAL_CLOSE_PAREN_IS( cur_eval, n ) )
7590 	        goto fake_end;
7591 
7592 	    break;
7593 
7594         case SRCLOSE:  /*  (*SCRIPT_RUN: ... )   */
7595 
7596             if (! isSCRIPT_RUN(script_run_begin, (U8 *) locinput, utf8_target))
7597             {
7598                 sayNO;
7599             }
7600 
7601             break;
7602 
7603 
7604         case ACCEPT:  /*  (*ACCEPT)  */
7605             if (scan->flags)
7606                 sv_yes_mark = MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
7607             if (ARG2L(scan)){
7608                 regnode *cursor;
7609                 for (cursor=scan;
7610                      cursor && OP(cursor)!=END;
7611                      cursor=regnext(cursor))
7612                 {
7613                     if ( OP(cursor)==CLOSE ){
7614                         n = ARG(cursor);
7615                         if ( n <= lastopen ) {
7616 			    CLOSE_CAPTURE;
7617                             if (n > rex->lastparen)
7618                                 rex->lastparen = n;
7619                             rex->lastcloseparen = n;
7620                             if ( n == ARG(scan) || EVAL_CLOSE_PAREN_IS(cur_eval, n) )
7621                                 break;
7622                         }
7623                     }
7624                 }
7625             }
7626 	    goto fake_end;
7627 	    /* NOTREACHED */
7628 
7629 	case GROUPP:  /*  (?(1))  */
7630 	    n = ARG(scan);  /* which paren pair */
7631 	    sw = cBOOL(rex->lastparen >= n && rex->offs[n].end != -1);
7632 	    break;
7633 
7634 	case NGROUPP:  /*  (?(<name>))  */
7635 	    /* reg_check_named_buff_matched returns 0 for no match */
7636 	    sw = cBOOL(0 < reg_check_named_buff_matched(rex,scan));
7637 	    break;
7638 
7639         case INSUBP:   /*  (?(R))  */
7640             n = ARG(scan);
7641             /* this does not need to use EVAL_CLOSE_PAREN macros, as the arg
7642              * of SCAN is already set up as matches a eval.close_paren */
7643             sw = cur_eval && (n == 0 || CUR_EVAL.close_paren == n);
7644             break;
7645 
7646         case DEFINEP:  /*  (?(DEFINE))  */
7647             sw = 0;
7648             break;
7649 
7650 	case IFTHEN:   /*  (?(cond)A|B)  */
7651 	    reginfo->poscache_iter = reginfo->poscache_maxiter; /* Void cache */
7652 	    if (sw)
7653 		next = NEXTOPER(NEXTOPER(scan));
7654 	    else {
7655 		next = scan + ARG(scan);
7656 		if (OP(next) == IFTHEN) /* Fake one. */
7657 		    next = NEXTOPER(NEXTOPER(next));
7658 	    }
7659 	    break;
7660 
7661 	case LOGICAL:  /* modifier for EVAL and IFMATCH */
7662 	    logical = scan->flags;
7663 	    break;
7664 
7665 /*******************************************************************
7666 
7667 The CURLYX/WHILEM pair of ops handle the most generic case of the /A*B/
7668 pattern, where A and B are subpatterns. (For simple A, CURLYM or
7669 STAR/PLUS/CURLY/CURLYN are used instead.)
7670 
7671 A*B is compiled as <CURLYX><A><WHILEM><B>
7672 
7673 On entry to the subpattern, CURLYX is called. This pushes a CURLYX
7674 state, which contains the current count, initialised to -1. It also sets
7675 cur_curlyx to point to this state, with any previous value saved in the
7676 state block.
7677 
7678 CURLYX then jumps straight to the WHILEM op, rather than executing A,
7679 since the pattern may possibly match zero times (i.e. it's a while {} loop
7680 rather than a do {} while loop).
7681 
7682 Each entry to WHILEM represents a successful match of A. The count in the
7683 CURLYX block is incremented, another WHILEM state is pushed, and execution
7684 passes to A or B depending on greediness and the current count.
7685 
7686 For example, if matching against the string a1a2a3b (where the aN are
7687 substrings that match /A/), then the match progresses as follows: (the
7688 pushed states are interspersed with the bits of strings matched so far):
7689 
7690     <CURLYX cnt=-1>
7691     <CURLYX cnt=0><WHILEM>
7692     <CURLYX cnt=1><WHILEM> a1 <WHILEM>
7693     <CURLYX cnt=2><WHILEM> a1 <WHILEM> a2 <WHILEM>
7694     <CURLYX cnt=3><WHILEM> a1 <WHILEM> a2 <WHILEM> a3 <WHILEM>
7695     <CURLYX cnt=3><WHILEM> a1 <WHILEM> a2 <WHILEM> a3 <WHILEM> b
7696 
7697 (Contrast this with something like CURLYM, which maintains only a single
7698 backtrack state:
7699 
7700     <CURLYM cnt=0> a1
7701     a1 <CURLYM cnt=1> a2
7702     a1 a2 <CURLYM cnt=2> a3
7703     a1 a2 a3 <CURLYM cnt=3> b
7704 )
7705 
7706 Each WHILEM state block marks a point to backtrack to upon partial failure
7707 of A or B, and also contains some minor state data related to that
7708 iteration.  The CURLYX block, pointed to by cur_curlyx, contains the
7709 overall state, such as the count, and pointers to the A and B ops.
7710 
7711 This is complicated slightly by nested CURLYX/WHILEM's. Since cur_curlyx
7712 must always point to the *current* CURLYX block, the rules are:
7713 
7714 When executing CURLYX, save the old cur_curlyx in the CURLYX state block,
7715 and set cur_curlyx to point the new block.
7716 
7717 When popping the CURLYX block after a successful or unsuccessful match,
7718 restore the previous cur_curlyx.
7719 
7720 When WHILEM is about to execute B, save the current cur_curlyx, and set it
7721 to the outer one saved in the CURLYX block.
7722 
7723 When popping the WHILEM block after a successful or unsuccessful B match,
7724 restore the previous cur_curlyx.
7725 
7726 Here's an example for the pattern (AI* BI)*BO
7727 I and O refer to inner and outer, C and W refer to CURLYX and WHILEM:
7728 
7729 cur_
7730 curlyx backtrack stack
7731 ------ ---------------
7732 NULL
7733 CO     <CO prev=NULL> <WO>
7734 CI     <CO prev=NULL> <WO> <CI prev=CO> <WI> ai
7735 CO     <CO prev=NULL> <WO> <CI prev=CO> <WI> ai <WI prev=CI> bi
7736 NULL   <CO prev=NULL> <WO> <CI prev=CO> <WI> ai <WI prev=CI> bi <WO prev=CO> bo
7737 
7738 At this point the pattern succeeds, and we work back down the stack to
7739 clean up, restoring as we go:
7740 
7741 CO     <CO prev=NULL> <WO> <CI prev=CO> <WI> ai <WI prev=CI> bi
7742 CI     <CO prev=NULL> <WO> <CI prev=CO> <WI> ai
7743 CO     <CO prev=NULL> <WO>
7744 NULL
7745 
7746 *******************************************************************/
7747 
7748 #define ST st->u.curlyx
7749 
7750 	case CURLYX:    /* start of /A*B/  (for complex A) */
7751 	{
7752 	    /* No need to save/restore up to this paren */
7753 	    I32 parenfloor = scan->flags;
7754 
7755 	    assert(next); /* keep Coverity happy */
7756 	    if (OP(PREVOPER(next)) == NOTHING) /* LONGJMP */
7757 		next += ARG(next);
7758 
7759 	    /* XXXX Probably it is better to teach regpush to support
7760 	       parenfloor > maxopenparen ... */
7761 	    if (parenfloor > (I32)rex->lastparen)
7762 		parenfloor = rex->lastparen; /* Pessimization... */
7763 
7764 	    ST.prev_curlyx= cur_curlyx;
7765 	    cur_curlyx = st;
7766 	    ST.cp = PL_savestack_ix;
7767 
7768 	    /* these fields contain the state of the current curly.
7769 	     * they are accessed by subsequent WHILEMs */
7770 	    ST.parenfloor = parenfloor;
7771 	    ST.me = scan;
7772 	    ST.B = next;
7773 	    ST.minmod = minmod;
7774 	    minmod = 0;
7775 	    ST.count = -1;	/* this will be updated by WHILEM */
7776 	    ST.lastloc = NULL;  /* this will be updated by WHILEM */
7777 
7778 	    PUSH_YES_STATE_GOTO(CURLYX_end, PREVOPER(next), locinput);
7779 	    NOT_REACHED; /* NOTREACHED */
7780 	}
7781 
7782 	case CURLYX_end: /* just finished matching all of A*B */
7783 	    cur_curlyx = ST.prev_curlyx;
7784 	    sayYES;
7785 	    NOT_REACHED; /* NOTREACHED */
7786 
7787 	case CURLYX_end_fail: /* just failed to match all of A*B */
7788 	    regcpblow(ST.cp);
7789 	    cur_curlyx = ST.prev_curlyx;
7790 	    sayNO;
7791 	    NOT_REACHED; /* NOTREACHED */
7792 
7793 
7794 #undef ST
7795 #define ST st->u.whilem
7796 
7797 	case WHILEM:     /* just matched an A in /A*B/  (for complex A) */
7798 	{
7799 	    /* see the discussion above about CURLYX/WHILEM */
7800 	    I32 n;
7801 	    int min, max;
7802 	    regnode *A;
7803 
7804 	    assert(cur_curlyx); /* keep Coverity happy */
7805 
7806 	    min = ARG1(cur_curlyx->u.curlyx.me);
7807 	    max = ARG2(cur_curlyx->u.curlyx.me);
7808 	    A = NEXTOPER(cur_curlyx->u.curlyx.me) + EXTRA_STEP_2ARGS;
7809 	    n = ++cur_curlyx->u.curlyx.count; /* how many A's matched */
7810 	    ST.save_lastloc = cur_curlyx->u.curlyx.lastloc;
7811 	    ST.cache_offset = 0;
7812 	    ST.cache_mask = 0;
7813 
7814 
7815             DEBUG_EXECUTE_r( Perl_re_exec_indentf( aTHX_  "WHILEM: matched %ld out of %d..%d\n",
7816                   depth, (long)n, min, max)
7817 	    );
7818 
7819 	    /* First just match a string of min A's. */
7820 
7821 	    if (n < min) {
7822                 ST.cp = regcppush(rex, cur_curlyx->u.curlyx.parenfloor, maxopenparen);
7823 		cur_curlyx->u.curlyx.lastloc = locinput;
7824 		REGCP_SET(ST.lastcp);
7825 
7826 		PUSH_STATE_GOTO(WHILEM_A_pre, A, locinput);
7827 		NOT_REACHED; /* NOTREACHED */
7828 	    }
7829 
7830 	    /* If degenerate A matches "", assume A done. */
7831 
7832 	    if (locinput == cur_curlyx->u.curlyx.lastloc) {
7833                 DEBUG_EXECUTE_r( Perl_re_exec_indentf( aTHX_  "WHILEM: empty match detected, trying continuation...\n",
7834                    depth)
7835 		);
7836 		goto do_whilem_B_max;
7837 	    }
7838 
7839 	    /* super-linear cache processing.
7840              *
7841              * The idea here is that for certain types of CURLYX/WHILEM -
7842              * principally those whose upper bound is infinity (and
7843              * excluding regexes that have things like \1 and other very
7844              * non-regular expresssiony things), then if a pattern like
7845              * /....A*.../ fails and we backtrack to the WHILEM, then we
7846              * make a note that this particular WHILEM op was at string
7847              * position 47 (say) when the rest of pattern failed. Then, if
7848              * we ever find ourselves back at that WHILEM, and at string
7849              * position 47 again, we can just fail immediately rather than
7850              * running the rest of the pattern again.
7851              *
7852              * This is very handy when patterns start to go
7853              * 'super-linear', like in (a+)*(a+)*(a+)*, where you end up
7854              * with a combinatorial explosion of backtracking.
7855              *
7856              * The cache is implemented as a bit array, with one bit per
7857              * string byte position per WHILEM op (up to 16) - so its
7858              * between 0.25 and 2x the string size.
7859              *
7860              * To avoid allocating a poscache buffer every time, we do an
7861              * initially countdown; only after we have  executed a WHILEM
7862              * op (string-length x #WHILEMs) times do we allocate the
7863              * cache.
7864              *
7865              * The top 4 bits of scan->flags byte say how many different
7866              * relevant CURLLYX/WHILEM op pairs there are, while the
7867              * bottom 4-bits is the identifying index number of this
7868              * WHILEM.
7869              */
7870 
7871 	    if (scan->flags) {
7872 
7873 		if (!reginfo->poscache_maxiter) {
7874 		    /* start the countdown: Postpone detection until we
7875 		     * know the match is not *that* much linear. */
7876 		    reginfo->poscache_maxiter
7877                         =    (reginfo->strend - reginfo->strbeg + 1)
7878                            * (scan->flags>>4);
7879 		    /* possible overflow for long strings and many CURLYX's */
7880 		    if (reginfo->poscache_maxiter < 0)
7881 			reginfo->poscache_maxiter = I32_MAX;
7882 		    reginfo->poscache_iter = reginfo->poscache_maxiter;
7883 		}
7884 
7885 		if (reginfo->poscache_iter-- == 0) {
7886 		    /* initialise cache */
7887 		    const SSize_t size = (reginfo->poscache_maxiter + 7)/8;
7888                     regmatch_info_aux *const aux = reginfo->info_aux;
7889 		    if (aux->poscache) {
7890 			if ((SSize_t)reginfo->poscache_size < size) {
7891 			    Renew(aux->poscache, size, char);
7892 			    reginfo->poscache_size = size;
7893 			}
7894 			Zero(aux->poscache, size, char);
7895 		    }
7896 		    else {
7897 			reginfo->poscache_size = size;
7898 			Newxz(aux->poscache, size, char);
7899 		    }
7900                     DEBUG_EXECUTE_r( Perl_re_printf( aTHX_
7901       "%sWHILEM: Detected a super-linear match, switching on caching%s...\n",
7902 			      PL_colors[4], PL_colors[5])
7903 		    );
7904 		}
7905 
7906 		if (reginfo->poscache_iter < 0) {
7907 		    /* have we already failed at this position? */
7908 		    SSize_t offset, mask;
7909 
7910                     reginfo->poscache_iter = -1; /* stop eventual underflow */
7911 		    offset  = (scan->flags & 0xf) - 1
7912                                 +   (locinput - reginfo->strbeg)
7913                                   * (scan->flags>>4);
7914 		    mask    = 1 << (offset % 8);
7915 		    offset /= 8;
7916 		    if (reginfo->info_aux->poscache[offset] & mask) {
7917                         DEBUG_EXECUTE_r( Perl_re_exec_indentf( aTHX_  "WHILEM: (cache) already tried at this position...\n",
7918                             depth)
7919 			);
7920                         cur_curlyx->u.curlyx.count--;
7921 			sayNO; /* cache records failure */
7922 		    }
7923 		    ST.cache_offset = offset;
7924 		    ST.cache_mask   = mask;
7925 		}
7926 	    }
7927 
7928 	    /* Prefer B over A for minimal matching. */
7929 
7930 	    if (cur_curlyx->u.curlyx.minmod) {
7931 		ST.save_curlyx = cur_curlyx;
7932 		cur_curlyx = cur_curlyx->u.curlyx.prev_curlyx;
7933 		PUSH_YES_STATE_GOTO(WHILEM_B_min, ST.save_curlyx->u.curlyx.B,
7934                                     locinput);
7935 		NOT_REACHED; /* NOTREACHED */
7936 	    }
7937 
7938 	    /* Prefer A over B for maximal matching. */
7939 
7940 	    if (n < max) { /* More greed allowed? */
7941                 ST.cp = regcppush(rex, cur_curlyx->u.curlyx.parenfloor,
7942                             maxopenparen);
7943 		cur_curlyx->u.curlyx.lastloc = locinput;
7944 		REGCP_SET(ST.lastcp);
7945 		PUSH_STATE_GOTO(WHILEM_A_max, A, locinput);
7946 		NOT_REACHED; /* NOTREACHED */
7947 	    }
7948 	    goto do_whilem_B_max;
7949 	}
7950 	NOT_REACHED; /* NOTREACHED */
7951 
7952 	case WHILEM_B_min: /* just matched B in a minimal match */
7953 	case WHILEM_B_max: /* just matched B in a maximal match */
7954 	    cur_curlyx = ST.save_curlyx;
7955 	    sayYES;
7956 	    NOT_REACHED; /* NOTREACHED */
7957 
7958 	case WHILEM_B_max_fail: /* just failed to match B in a maximal match */
7959 	    cur_curlyx = ST.save_curlyx;
7960 	    cur_curlyx->u.curlyx.lastloc = ST.save_lastloc;
7961 	    cur_curlyx->u.curlyx.count--;
7962 	    CACHEsayNO;
7963 	    NOT_REACHED; /* NOTREACHED */
7964 
7965 	case WHILEM_A_min_fail: /* just failed to match A in a minimal match */
7966 	    /* FALLTHROUGH */
7967 	case WHILEM_A_pre_fail: /* just failed to match even minimal A */
7968 	    REGCP_UNWIND(ST.lastcp);
7969             regcppop(rex, &maxopenparen);
7970 	    cur_curlyx->u.curlyx.lastloc = ST.save_lastloc;
7971 	    cur_curlyx->u.curlyx.count--;
7972 	    CACHEsayNO;
7973 	    NOT_REACHED; /* NOTREACHED */
7974 
7975 	case WHILEM_A_max_fail: /* just failed to match A in a maximal match */
7976 	    REGCP_UNWIND(ST.lastcp);
7977             regcppop(rex, &maxopenparen); /* Restore some previous $<digit>s? */
7978             DEBUG_EXECUTE_r(Perl_re_exec_indentf( aTHX_  "WHILEM: failed, trying continuation...\n",
7979                 depth)
7980 	    );
7981 	  do_whilem_B_max:
7982 	    if (cur_curlyx->u.curlyx.count >= REG_INFTY
7983 		&& ckWARN(WARN_REGEXP)
7984 		&& !reginfo->warned)
7985 	    {
7986                 reginfo->warned	= TRUE;
7987 		Perl_warner(aTHX_ packWARN(WARN_REGEXP),
7988 		     "Complex regular subexpression recursion limit (%d) "
7989 		     "exceeded",
7990 		     REG_INFTY - 1);
7991 	    }
7992 
7993 	    /* now try B */
7994 	    ST.save_curlyx = cur_curlyx;
7995 	    cur_curlyx = cur_curlyx->u.curlyx.prev_curlyx;
7996 	    PUSH_YES_STATE_GOTO(WHILEM_B_max, ST.save_curlyx->u.curlyx.B,
7997                                 locinput);
7998 	    NOT_REACHED; /* NOTREACHED */
7999 
8000 	case WHILEM_B_min_fail: /* just failed to match B in a minimal match */
8001 	    cur_curlyx = ST.save_curlyx;
8002 
8003 	    if (cur_curlyx->u.curlyx.count >= /*max*/ARG2(cur_curlyx->u.curlyx.me)) {
8004 		/* Maximum greed exceeded */
8005 		if (cur_curlyx->u.curlyx.count >= REG_INFTY
8006 		    && ckWARN(WARN_REGEXP)
8007                     && !reginfo->warned)
8008 		{
8009                     reginfo->warned	= TRUE;
8010 		    Perl_warner(aTHX_ packWARN(WARN_REGEXP),
8011 			"Complex regular subexpression recursion "
8012 			"limit (%d) exceeded",
8013 			REG_INFTY - 1);
8014 		}
8015 		cur_curlyx->u.curlyx.count--;
8016 		CACHEsayNO;
8017 	    }
8018 
8019             DEBUG_EXECUTE_r(Perl_re_exec_indentf( aTHX_  "WHILEM: B min fail: trying longer...\n", depth)
8020 	    );
8021 	    /* Try grabbing another A and see if it helps. */
8022 	    cur_curlyx->u.curlyx.lastloc = locinput;
8023             ST.cp = regcppush(rex, cur_curlyx->u.curlyx.parenfloor,
8024                             maxopenparen);
8025 	    REGCP_SET(ST.lastcp);
8026 	    PUSH_STATE_GOTO(WHILEM_A_min,
8027 		/*A*/ NEXTOPER(ST.save_curlyx->u.curlyx.me) + EXTRA_STEP_2ARGS,
8028                 locinput);
8029 	    NOT_REACHED; /* NOTREACHED */
8030 
8031 #undef  ST
8032 #define ST st->u.branch
8033 
8034 	case BRANCHJ:	    /*  /(...|A|...)/ with long next pointer */
8035 	    next = scan + ARG(scan);
8036 	    if (next == scan)
8037 		next = NULL;
8038 	    scan = NEXTOPER(scan);
8039 	    /* FALLTHROUGH */
8040 
8041 	case BRANCH:	    /*  /(...|A|...)/ */
8042 	    scan = NEXTOPER(scan); /* scan now points to inner node */
8043 	    ST.lastparen = rex->lastparen;
8044 	    ST.lastcloseparen = rex->lastcloseparen;
8045 	    ST.next_branch = next;
8046 	    REGCP_SET(ST.cp);
8047 
8048 	    /* Now go into the branch */
8049 	    if (has_cutgroup) {
8050 	        PUSH_YES_STATE_GOTO(BRANCH_next, scan, locinput);
8051 	    } else {
8052 	        PUSH_STATE_GOTO(BRANCH_next, scan, locinput);
8053 	    }
8054 	    NOT_REACHED; /* NOTREACHED */
8055 
8056         case CUTGROUP:  /*  /(*THEN)/  */
8057             sv_yes_mark = st->u.mark.mark_name = scan->flags
8058                 ? MUTABLE_SV(rexi->data->data[ ARG( scan ) ])
8059                 : NULL;
8060             PUSH_STATE_GOTO(CUTGROUP_next, next, locinput);
8061             NOT_REACHED; /* NOTREACHED */
8062 
8063         case CUTGROUP_next_fail:
8064             do_cutgroup = 1;
8065             no_final = 1;
8066             if (st->u.mark.mark_name)
8067                 sv_commit = st->u.mark.mark_name;
8068             sayNO;
8069             NOT_REACHED; /* NOTREACHED */
8070 
8071         case BRANCH_next:
8072             sayYES;
8073             NOT_REACHED; /* NOTREACHED */
8074 
8075 	case BRANCH_next_fail: /* that branch failed; try the next, if any */
8076 	    if (do_cutgroup) {
8077 	        do_cutgroup = 0;
8078 	        no_final = 0;
8079 	    }
8080 	    REGCP_UNWIND(ST.cp);
8081             UNWIND_PAREN(ST.lastparen, ST.lastcloseparen);
8082 	    scan = ST.next_branch;
8083 	    /* no more branches? */
8084 	    if (!scan || (OP(scan) != BRANCH && OP(scan) != BRANCHJ)) {
8085 	        DEBUG_EXECUTE_r({
8086                     Perl_re_exec_indentf( aTHX_  "%sBRANCH failed...%s\n",
8087                         depth,
8088 			PL_colors[4],
8089 			PL_colors[5] );
8090 		});
8091 		sayNO_SILENT;
8092             }
8093 	    continue; /* execute next BRANCH[J] op */
8094             /* NOTREACHED */
8095 
8096 	case MINMOD: /* next op will be non-greedy, e.g. A*?  */
8097 	    minmod = 1;
8098 	    break;
8099 
8100 #undef  ST
8101 #define ST st->u.curlym
8102 
8103 	case CURLYM:	/* /A{m,n}B/ where A is fixed-length */
8104 
8105 	    /* This is an optimisation of CURLYX that enables us to push
8106 	     * only a single backtracking state, no matter how many matches
8107 	     * there are in {m,n}. It relies on the pattern being constant
8108 	     * length, with no parens to influence future backrefs
8109 	     */
8110 
8111 	    ST.me = scan;
8112 	    scan = NEXTOPER(scan) + NODE_STEP_REGNODE;
8113 
8114 	    ST.lastparen      = rex->lastparen;
8115 	    ST.lastcloseparen = rex->lastcloseparen;
8116 
8117 	    /* if paren positive, emulate an OPEN/CLOSE around A */
8118 	    if (ST.me->flags) {
8119 		U32 paren = ST.me->flags;
8120 		if (paren > maxopenparen)
8121 		    maxopenparen = paren;
8122 		scan += NEXT_OFF(scan); /* Skip former OPEN. */
8123 	    }
8124 	    ST.A = scan;
8125 	    ST.B = next;
8126 	    ST.alen = 0;
8127 	    ST.count = 0;
8128 	    ST.minmod = minmod;
8129 	    minmod = 0;
8130 	    ST.c1 = CHRTEST_UNINIT;
8131 	    REGCP_SET(ST.cp);
8132 
8133 	    if (!(ST.minmod ? ARG1(ST.me) : ARG2(ST.me))) /* min/max */
8134 		goto curlym_do_B;
8135 
8136 	  curlym_do_A: /* execute the A in /A{m,n}B/  */
8137 	    PUSH_YES_STATE_GOTO(CURLYM_A, ST.A, locinput); /* match A */
8138 	    NOT_REACHED; /* NOTREACHED */
8139 
8140 	case CURLYM_A: /* we've just matched an A */
8141 	    ST.count++;
8142 	    /* after first match, determine A's length: u.curlym.alen */
8143 	    if (ST.count == 1) {
8144 		if (reginfo->is_utf8_target) {
8145 		    char *s = st->locinput;
8146 		    while (s < locinput) {
8147 			ST.alen++;
8148 			s += UTF8SKIP(s);
8149 		    }
8150 		}
8151 		else {
8152 		    ST.alen = locinput - st->locinput;
8153 		}
8154 		if (ST.alen == 0)
8155 		    ST.count = ST.minmod ? ARG1(ST.me) : ARG2(ST.me);
8156 	    }
8157 	    DEBUG_EXECUTE_r(
8158                 Perl_re_exec_indentf( aTHX_  "CURLYM now matched %" IVdf " times, len=%" IVdf "...\n",
8159                           depth, (IV) ST.count, (IV)ST.alen)
8160 	    );
8161 
8162             if (EVAL_CLOSE_PAREN_IS_TRUE(cur_eval,(U32)ST.me->flags))
8163 	        goto fake_end;
8164 
8165 	    {
8166 		I32 max = (ST.minmod ? ARG1(ST.me) : ARG2(ST.me));
8167 		if ( max == REG_INFTY || ST.count < max )
8168 		    goto curlym_do_A; /* try to match another A */
8169 	    }
8170 	    goto curlym_do_B; /* try to match B */
8171 
8172 	case CURLYM_A_fail: /* just failed to match an A */
8173 	    REGCP_UNWIND(ST.cp);
8174 
8175 
8176 	    if (ST.minmod || ST.count < ARG1(ST.me) /* min*/
8177                 || EVAL_CLOSE_PAREN_IS_TRUE(cur_eval,(U32)ST.me->flags))
8178 		sayNO;
8179 
8180 	  curlym_do_B: /* execute the B in /A{m,n}B/  */
8181 	    if (ST.c1 == CHRTEST_UNINIT) {
8182 		/* calculate c1 and c2 for possible match of 1st char
8183 		 * following curly */
8184 		ST.c1 = ST.c2 = CHRTEST_VOID;
8185                 assert(ST.B);
8186 		if (HAS_TEXT(ST.B) || JUMPABLE(ST.B)) {
8187 		    regnode *text_node = ST.B;
8188 		    if (! HAS_TEXT(text_node))
8189 			FIND_NEXT_IMPT(text_node);
8190 	            /* this used to be
8191 
8192 	                (HAS_TEXT(text_node) && PL_regkind[OP(text_node)] == EXACT)
8193 
8194 	            	But the former is redundant in light of the latter.
8195 
8196 	            	if this changes back then the macro for
8197 	            	IS_TEXT and friends need to change.
8198 	             */
8199 		    if (PL_regkind[OP(text_node)] == EXACT) {
8200                         if (! S_setup_EXACTISH_ST_c1_c2(aTHX_
8201                            text_node, &ST.c1, ST.c1_utf8, &ST.c2, ST.c2_utf8,
8202                            reginfo))
8203                         {
8204                             sayNO;
8205                         }
8206 		    }
8207 		}
8208 	    }
8209 
8210 	    DEBUG_EXECUTE_r(
8211                 Perl_re_exec_indentf( aTHX_  "CURLYM trying tail with matches=%" IVdf "...\n",
8212                     depth, (IV)ST.count)
8213 		);
8214 	    if (! NEXTCHR_IS_EOS && ST.c1 != CHRTEST_VOID) {
8215                 if (! UTF8_IS_INVARIANT(nextchr) && utf8_target) {
8216                     if (memNE(locinput, ST.c1_utf8, UTF8SKIP(locinput))
8217                         && memNE(locinput, ST.c2_utf8, UTF8SKIP(locinput)))
8218                     {
8219                         /* simulate B failing */
8220                         DEBUG_OPTIMISE_r(
8221                             Perl_re_exec_indentf( aTHX_  "CURLYM Fast bail next target=0x%" UVXf " c1=0x%" UVXf " c2=0x%" UVXf "\n",
8222                                 depth,
8223                                 valid_utf8_to_uvchr((U8 *) locinput, NULL),
8224                                 valid_utf8_to_uvchr(ST.c1_utf8, NULL),
8225                                 valid_utf8_to_uvchr(ST.c2_utf8, NULL))
8226                         );
8227                         state_num = CURLYM_B_fail;
8228                         goto reenter_switch;
8229                     }
8230                 }
8231                 else if (nextchr != ST.c1 && nextchr != ST.c2) {
8232                     /* simulate B failing */
8233                     DEBUG_OPTIMISE_r(
8234                         Perl_re_exec_indentf( aTHX_  "CURLYM Fast bail next target=0x%X c1=0x%X c2=0x%X\n",
8235                             depth,
8236                             (int) nextchr, ST.c1, ST.c2)
8237                     );
8238                     state_num = CURLYM_B_fail;
8239                     goto reenter_switch;
8240                 }
8241             }
8242 
8243 	    if (ST.me->flags) {
8244 		/* emulate CLOSE: mark current A as captured */
8245 		I32 paren = ST.me->flags;
8246 		if (ST.count) {
8247 		    rex->offs[paren].start
8248 			= HOPc(locinput, -ST.alen) - reginfo->strbeg;
8249 		    rex->offs[paren].end = locinput - reginfo->strbeg;
8250 		    if ((U32)paren > rex->lastparen)
8251 			rex->lastparen = paren;
8252 		    rex->lastcloseparen = paren;
8253 		}
8254 		else
8255 		    rex->offs[paren].end = -1;
8256 
8257                 if (EVAL_CLOSE_PAREN_IS_TRUE(cur_eval,(U32)ST.me->flags))
8258 		{
8259 		    if (ST.count)
8260 	                goto fake_end;
8261 	            else
8262 	                sayNO;
8263 	        }
8264 	    }
8265 
8266 	    PUSH_STATE_GOTO(CURLYM_B, ST.B, locinput); /* match B */
8267 	    NOT_REACHED; /* NOTREACHED */
8268 
8269 	case CURLYM_B_fail: /* just failed to match a B */
8270 	    REGCP_UNWIND(ST.cp);
8271             UNWIND_PAREN(ST.lastparen, ST.lastcloseparen);
8272 	    if (ST.minmod) {
8273 		I32 max = ARG2(ST.me);
8274 		if (max != REG_INFTY && ST.count == max)
8275 		    sayNO;
8276 		goto curlym_do_A; /* try to match a further A */
8277 	    }
8278 	    /* backtrack one A */
8279 	    if (ST.count == ARG1(ST.me) /* min */)
8280 		sayNO;
8281 	    ST.count--;
8282 	    SET_locinput(HOPc(locinput, -ST.alen));
8283 	    goto curlym_do_B; /* try to match B */
8284 
8285 #undef ST
8286 #define ST st->u.curly
8287 
8288 #define CURLY_SETPAREN(paren, success) \
8289     if (paren) { \
8290 	if (success) { \
8291 	    rex->offs[paren].start = HOPc(locinput, -1) - reginfo->strbeg; \
8292 	    rex->offs[paren].end = locinput - reginfo->strbeg; \
8293 	    if (paren > rex->lastparen) \
8294 		rex->lastparen = paren; \
8295 	    rex->lastcloseparen = paren; \
8296 	} \
8297 	else { \
8298 	    rex->offs[paren].end = -1; \
8299 	    rex->lastparen      = ST.lastparen; \
8300 	    rex->lastcloseparen = ST.lastcloseparen; \
8301 	} \
8302     }
8303 
8304         case STAR:		/*  /A*B/ where A is width 1 char */
8305 	    ST.paren = 0;
8306 	    ST.min = 0;
8307 	    ST.max = REG_INFTY;
8308 	    scan = NEXTOPER(scan);
8309 	    goto repeat;
8310 
8311         case PLUS:		/*  /A+B/ where A is width 1 char */
8312 	    ST.paren = 0;
8313 	    ST.min = 1;
8314 	    ST.max = REG_INFTY;
8315 	    scan = NEXTOPER(scan);
8316 	    goto repeat;
8317 
8318 	case CURLYN:		/*  /(A){m,n}B/ where A is width 1 char */
8319             ST.paren = scan->flags;	/* Which paren to set */
8320             ST.lastparen      = rex->lastparen;
8321 	    ST.lastcloseparen = rex->lastcloseparen;
8322 	    if (ST.paren > maxopenparen)
8323 		maxopenparen = ST.paren;
8324 	    ST.min = ARG1(scan);  /* min to match */
8325 	    ST.max = ARG2(scan);  /* max to match */
8326             if (EVAL_CLOSE_PAREN_IS_TRUE(cur_eval,(U32)ST.paren))
8327             {
8328 	        ST.min=1;
8329 	        ST.max=1;
8330 	    }
8331             scan = regnext(NEXTOPER(scan) + NODE_STEP_REGNODE);
8332 	    goto repeat;
8333 
8334 	case CURLY:		/*  /A{m,n}B/ where A is width 1 char */
8335 	    ST.paren = 0;
8336 	    ST.min = ARG1(scan);  /* min to match */
8337 	    ST.max = ARG2(scan);  /* max to match */
8338 	    scan = NEXTOPER(scan) + NODE_STEP_REGNODE;
8339 	  repeat:
8340 	    /*
8341 	    * Lookahead to avoid useless match attempts
8342 	    * when we know what character comes next.
8343 	    *
8344 	    * Used to only do .*x and .*?x, but now it allows
8345 	    * for )'s, ('s and (?{ ... })'s to be in the way
8346 	    * of the quantifier and the EXACT-like node.  -- japhy
8347 	    */
8348 
8349 	    assert(ST.min <= ST.max);
8350             if (! HAS_TEXT(next) && ! JUMPABLE(next)) {
8351                 ST.c1 = ST.c2 = CHRTEST_VOID;
8352             }
8353             else {
8354 		regnode *text_node = next;
8355 
8356 		if (! HAS_TEXT(text_node))
8357 		    FIND_NEXT_IMPT(text_node);
8358 
8359 		if (! HAS_TEXT(text_node))
8360 		    ST.c1 = ST.c2 = CHRTEST_VOID;
8361 		else {
8362 		    if ( PL_regkind[OP(text_node)] != EXACT ) {
8363 			ST.c1 = ST.c2 = CHRTEST_VOID;
8364 		    }
8365 		    else {
8366 
8367                     /*  Currently we only get here when
8368 
8369                         PL_rekind[OP(text_node)] == EXACT
8370 
8371                         if this changes back then the macro for IS_TEXT and
8372                         friends need to change. */
8373                         if (! S_setup_EXACTISH_ST_c1_c2(aTHX_
8374                            text_node, &ST.c1, ST.c1_utf8, &ST.c2, ST.c2_utf8,
8375                            reginfo))
8376                         {
8377                             sayNO;
8378                         }
8379                     }
8380 		}
8381 	    }
8382 
8383 	    ST.A = scan;
8384 	    ST.B = next;
8385 	    if (minmod) {
8386                 char *li = locinput;
8387 		minmod = 0;
8388 		if (ST.min &&
8389                         regrepeat(rex, &li, ST.A, reginfo, ST.min)
8390                             < ST.min)
8391 		    sayNO;
8392                 SET_locinput(li);
8393 		ST.count = ST.min;
8394 		REGCP_SET(ST.cp);
8395 		if (ST.c1 == CHRTEST_VOID)
8396 		    goto curly_try_B_min;
8397 
8398 		ST.oldloc = locinput;
8399 
8400 		/* set ST.maxpos to the furthest point along the
8401 		 * string that could possibly match */
8402 		if  (ST.max == REG_INFTY) {
8403 		    ST.maxpos = reginfo->strend - 1;
8404 		    if (utf8_target)
8405 			while (UTF8_IS_CONTINUATION(*(U8*)ST.maxpos))
8406 			    ST.maxpos--;
8407 		}
8408 		else if (utf8_target) {
8409 		    int m = ST.max - ST.min;
8410 		    for (ST.maxpos = locinput;
8411 			 m >0 && ST.maxpos < reginfo->strend; m--)
8412 			ST.maxpos += UTF8SKIP(ST.maxpos);
8413 		}
8414 		else {
8415 		    ST.maxpos = locinput + ST.max - ST.min;
8416 		    if (ST.maxpos >= reginfo->strend)
8417 			ST.maxpos = reginfo->strend - 1;
8418 		}
8419 		goto curly_try_B_min_known;
8420 
8421 	    }
8422 	    else {
8423                 /* avoid taking address of locinput, so it can remain
8424                  * a register var */
8425                 char *li = locinput;
8426                 ST.count = regrepeat(rex, &li, ST.A, reginfo, ST.max);
8427 		if (ST.count < ST.min)
8428 		    sayNO;
8429                 SET_locinput(li);
8430 		if ((ST.count > ST.min)
8431 		    && (PL_regkind[OP(ST.B)] == EOL) && (OP(ST.B) != MEOL))
8432 		{
8433 		    /* A{m,n} must come at the end of the string, there's
8434 		     * no point in backing off ... */
8435 		    ST.min = ST.count;
8436 		    /* ...except that $ and \Z can match before *and* after
8437 		       newline at the end.  Consider "\n\n" =~ /\n+\Z\n/.
8438 		       We may back off by one in this case. */
8439 		    if (UCHARAT(locinput - 1) == '\n' && OP(ST.B) != EOS)
8440 			ST.min--;
8441 		}
8442 		REGCP_SET(ST.cp);
8443 		goto curly_try_B_max;
8444 	    }
8445 	    NOT_REACHED; /* NOTREACHED */
8446 
8447 	case CURLY_B_min_known_fail:
8448 	    /* failed to find B in a non-greedy match where c1,c2 valid */
8449 
8450 	    REGCP_UNWIND(ST.cp);
8451             if (ST.paren) {
8452                 UNWIND_PAREN(ST.lastparen, ST.lastcloseparen);
8453             }
8454 	    /* Couldn't or didn't -- move forward. */
8455 	    ST.oldloc = locinput;
8456 	    if (utf8_target)
8457 		locinput += UTF8SKIP(locinput);
8458 	    else
8459 		locinput++;
8460 	    ST.count++;
8461 	  curly_try_B_min_known:
8462 	     /* find the next place where 'B' could work, then call B */
8463 	    {
8464 		int n;
8465 		if (utf8_target) {
8466 		    n = (ST.oldloc == locinput) ? 0 : 1;
8467 		    if (ST.c1 == ST.c2) {
8468 			/* set n to utf8_distance(oldloc, locinput) */
8469 			while (locinput <= ST.maxpos
8470                               && memNE(locinput, ST.c1_utf8, UTF8SKIP(locinput)))
8471                         {
8472 			    locinput += UTF8SKIP(locinput);
8473 			    n++;
8474 			}
8475 		    }
8476 		    else {
8477 			/* set n to utf8_distance(oldloc, locinput) */
8478 			while (locinput <= ST.maxpos
8479                               && memNE(locinput, ST.c1_utf8, UTF8SKIP(locinput))
8480                               && memNE(locinput, ST.c2_utf8, UTF8SKIP(locinput)))
8481                         {
8482 			    locinput += UTF8SKIP(locinput);
8483 			    n++;
8484 			}
8485 		    }
8486 		}
8487 		else {  /* Not utf8_target */
8488 		    if (ST.c1 == ST.c2) {
8489                         locinput = (char *) memchr(locinput,
8490                                                    ST.c1,
8491                                                    ST.maxpos + 1 - locinput);
8492                         if (! locinput) {
8493                             locinput = ST.maxpos + 1;
8494                         }
8495 		    }
8496                     else {
8497                         U8 c1_c2_bits_differing = ST.c1 ^ ST.c2;
8498 
8499                         if (! isPOWER_OF_2(c1_c2_bits_differing)) {
8500                             while (   locinput <= ST.maxpos
8501                                    && UCHARAT(locinput) != ST.c1
8502                                    && UCHARAT(locinput) != ST.c2)
8503                             {
8504                                 locinput++;
8505                             }
8506                         }
8507                         else {
8508                             /* If c1 and c2 only differ by a single bit, we can
8509                              * avoid a conditional each time through the loop,
8510                              * at the expense of a little preliminary setup and
8511                              * an extra mask each iteration.  By masking out
8512                              * that bit, we match exactly two characters, c1
8513                              * and c2, and so we don't have to test for both.
8514                              * On both ASCII and EBCDIC platforms, most of the
8515                              * ASCII-range and Latin1-range folded equivalents
8516                              * differ only in a single bit, so this is actually
8517                              * the most common case. (e.g. 'A' 0x41 vs 'a'
8518                              * 0x61). */
8519                             U8 c1_masked = ST.c1 &~ c1_c2_bits_differing;
8520                             U8 c1_c2_mask = ~ c1_c2_bits_differing;
8521                             while (   locinput <= ST.maxpos
8522                                    && (UCHARAT(locinput) & c1_c2_mask)
8523                                                                 != c1_masked)
8524                             {
8525                                 locinput++;
8526                             }
8527                         }
8528                     }
8529 		    n = locinput - ST.oldloc;
8530 		}
8531 		if (locinput > ST.maxpos)
8532 		    sayNO;
8533 		if (n) {
8534                     /* In /a{m,n}b/, ST.oldloc is at "a" x m, locinput is
8535                      * at b; check that everything between oldloc and
8536                      * locinput matches */
8537                     char *li = ST.oldloc;
8538 		    ST.count += n;
8539                     if (regrepeat(rex, &li, ST.A, reginfo, n) < n)
8540 			sayNO;
8541                     assert(n == REG_INFTY || locinput == li);
8542 		}
8543 		CURLY_SETPAREN(ST.paren, ST.count);
8544                 if (EVAL_CLOSE_PAREN_IS_TRUE(cur_eval,(U32)ST.paren))
8545 		    goto fake_end;
8546 		PUSH_STATE_GOTO(CURLY_B_min_known, ST.B, locinput);
8547 	    }
8548 	    NOT_REACHED; /* NOTREACHED */
8549 
8550 	case CURLY_B_min_fail:
8551 	    /* failed to find B in a non-greedy match where c1,c2 invalid */
8552 
8553 	    REGCP_UNWIND(ST.cp);
8554             if (ST.paren) {
8555                 UNWIND_PAREN(ST.lastparen, ST.lastcloseparen);
8556             }
8557 	    /* failed -- move forward one */
8558             {
8559                 char *li = locinput;
8560                 if (!regrepeat(rex, &li, ST.A, reginfo, 1)) {
8561                     sayNO;
8562                 }
8563                 locinput = li;
8564             }
8565             {
8566 		ST.count++;
8567 		if (ST.count <= ST.max || (ST.max == REG_INFTY &&
8568 			ST.count > 0)) /* count overflow ? */
8569 		{
8570 		  curly_try_B_min:
8571 		    CURLY_SETPAREN(ST.paren, ST.count);
8572                     if (EVAL_CLOSE_PAREN_IS_TRUE(cur_eval,(U32)ST.paren))
8573                         goto fake_end;
8574 		    PUSH_STATE_GOTO(CURLY_B_min, ST.B, locinput);
8575 		}
8576 	    }
8577             sayNO;
8578 	    NOT_REACHED; /* NOTREACHED */
8579 
8580           curly_try_B_max:
8581 	    /* a successful greedy match: now try to match B */
8582             if (EVAL_CLOSE_PAREN_IS_TRUE(cur_eval,(U32)ST.paren))
8583                 goto fake_end;
8584 	    {
8585 		bool could_match = locinput < reginfo->strend;
8586 
8587 		/* If it could work, try it. */
8588                 if (ST.c1 != CHRTEST_VOID && could_match) {
8589                     if (! UTF8_IS_INVARIANT(UCHARAT(locinput)) && utf8_target)
8590                     {
8591                         could_match = memEQ(locinput,
8592                                             ST.c1_utf8,
8593                                             UTF8SKIP(locinput))
8594                                     || memEQ(locinput,
8595                                              ST.c2_utf8,
8596                                              UTF8SKIP(locinput));
8597                     }
8598                     else {
8599                         could_match = UCHARAT(locinput) == ST.c1
8600                                       || UCHARAT(locinput) == ST.c2;
8601                     }
8602                 }
8603                 if (ST.c1 == CHRTEST_VOID || could_match) {
8604 		    CURLY_SETPAREN(ST.paren, ST.count);
8605 		    PUSH_STATE_GOTO(CURLY_B_max, ST.B, locinput);
8606 		    NOT_REACHED; /* NOTREACHED */
8607 		}
8608 	    }
8609 	    /* FALLTHROUGH */
8610 
8611 	case CURLY_B_max_fail:
8612 	    /* failed to find B in a greedy match */
8613 
8614 	    REGCP_UNWIND(ST.cp);
8615             if (ST.paren) {
8616                 UNWIND_PAREN(ST.lastparen, ST.lastcloseparen);
8617             }
8618 	    /*  back up. */
8619 	    if (--ST.count < ST.min)
8620 		sayNO;
8621 	    locinput = HOPc(locinput, -1);
8622 	    goto curly_try_B_max;
8623 
8624 #undef ST
8625 
8626 	case END: /*  last op of main pattern  */
8627           fake_end:
8628 	    if (cur_eval) {
8629 		/* we've just finished A in /(??{A})B/; now continue with B */
8630                 SET_RECURSE_LOCINPUT("FAKE-END[before]", CUR_EVAL.prev_recurse_locinput);
8631 		st->u.eval.prev_rex = rex_sv;		/* inner */
8632 
8633                 /* Save *all* the positions. */
8634                 st->u.eval.cp = regcppush(rex, 0, maxopenparen);
8635                 rex_sv = CUR_EVAL.prev_rex;
8636 		is_utf8_pat = reginfo->is_utf8_pat = cBOOL(RX_UTF8(rex_sv));
8637 		SET_reg_curpm(rex_sv);
8638 		rex = ReANY(rex_sv);
8639 		rexi = RXi_GET(rex);
8640 
8641                 st->u.eval.prev_curlyx = cur_curlyx;
8642                 cur_curlyx = CUR_EVAL.prev_curlyx;
8643 
8644 		REGCP_SET(st->u.eval.lastcp);
8645 
8646 		/* Restore parens of the outer rex without popping the
8647 		 * savestack */
8648                 regcp_restore(rex, CUR_EVAL.lastcp, &maxopenparen);
8649 
8650 		st->u.eval.prev_eval = cur_eval;
8651                 cur_eval = CUR_EVAL.prev_eval;
8652 		DEBUG_EXECUTE_r(
8653                     Perl_re_exec_indentf( aTHX_  "END: EVAL trying tail ... (cur_eval=%p)\n",
8654                                       depth, cur_eval););
8655                 if ( nochange_depth )
8656 	            nochange_depth--;
8657 
8658                 SET_RECURSE_LOCINPUT("FAKE-END[after]", cur_eval->locinput);
8659 
8660                 PUSH_YES_STATE_GOTO(EVAL_postponed_AB, st->u.eval.prev_eval->u.eval.B,
8661                                     locinput); /* match B */
8662 	    }
8663 
8664 	    if (locinput < reginfo->till) {
8665                 DEBUG_EXECUTE_r(Perl_re_printf( aTHX_
8666                                       "%sEND: Match possible, but length=%ld is smaller than requested=%ld, failing!%s\n",
8667 				      PL_colors[4],
8668 				      (long)(locinput - startpos),
8669 				      (long)(reginfo->till - startpos),
8670 				      PL_colors[5]));
8671 
8672 		sayNO_SILENT;		/* Cannot match: too short. */
8673 	    }
8674 	    sayYES;			/* Success! */
8675 
8676 	case SUCCEED: /* successful SUSPEND/UNLESSM/IFMATCH/CURLYM */
8677 	    DEBUG_EXECUTE_r(
8678             Perl_re_exec_indentf( aTHX_  "%sSUCCEED: subpattern success...%s\n",
8679                 depth, PL_colors[4], PL_colors[5]));
8680 	    sayYES;			/* Success! */
8681 
8682 #undef  ST
8683 #define ST st->u.ifmatch
8684 
8685         {
8686             char *newstart;
8687 
8688 	case SUSPEND:	/* (?>A) */
8689 	    ST.wanted = 1;
8690 	    newstart = locinput;
8691 	    goto do_ifmatch;
8692 
8693 	case UNLESSM:	/* -ve lookaround: (?!A), or with flags, (?<!A) */
8694 	    ST.wanted = 0;
8695 	    goto ifmatch_trivial_fail_test;
8696 
8697 	case IFMATCH:	/* +ve lookaround: (?=A), or with flags, (?<=A) */
8698 	    ST.wanted = 1;
8699 	  ifmatch_trivial_fail_test:
8700 	    if (scan->flags) {
8701 		char * const s = HOPBACKc(locinput, scan->flags);
8702 		if (!s) {
8703 		    /* trivial fail */
8704 		    if (logical) {
8705 			logical = 0;
8706 			sw = 1 - cBOOL(ST.wanted);
8707 		    }
8708 		    else if (ST.wanted)
8709 			sayNO;
8710 		    next = scan + ARG(scan);
8711 		    if (next == scan)
8712 			next = NULL;
8713 		    break;
8714 		}
8715 		newstart = s;
8716 	    }
8717 	    else
8718 		newstart = locinput;
8719 
8720 	  do_ifmatch:
8721 	    ST.me = scan;
8722 	    ST.logical = logical;
8723 	    logical = 0; /* XXX: reset state of logical once it has been saved into ST */
8724 
8725 	    /* execute body of (?...A) */
8726 	    PUSH_YES_STATE_GOTO(IFMATCH_A, NEXTOPER(NEXTOPER(scan)), newstart);
8727 	    NOT_REACHED; /* NOTREACHED */
8728         }
8729 
8730 	case IFMATCH_A_fail: /* body of (?...A) failed */
8731 	    ST.wanted = !ST.wanted;
8732 	    /* FALLTHROUGH */
8733 
8734 	case IFMATCH_A: /* body of (?...A) succeeded */
8735 	    if (ST.logical) {
8736 		sw = cBOOL(ST.wanted);
8737 	    }
8738 	    else if (!ST.wanted)
8739 		sayNO;
8740 
8741 	    if (OP(ST.me) != SUSPEND) {
8742                 /* restore old position except for (?>...) */
8743 		locinput = st->locinput;
8744 	    }
8745 	    scan = ST.me + ARG(ST.me);
8746 	    if (scan == ST.me)
8747 		scan = NULL;
8748 	    continue; /* execute B */
8749 
8750 #undef ST
8751 
8752 	case LONGJMP: /*  alternative with many branches compiles to
8753                        * (BRANCHJ; EXACT ...; LONGJMP ) x N */
8754 	    next = scan + ARG(scan);
8755 	    if (next == scan)
8756 		next = NULL;
8757 	    break;
8758 
8759 	case COMMIT:  /*  (*COMMIT)  */
8760 	    reginfo->cutpoint = reginfo->strend;
8761 	    /* FALLTHROUGH */
8762 
8763 	case PRUNE:   /*  (*PRUNE)   */
8764             if (scan->flags)
8765 	        sv_yes_mark = sv_commit = MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
8766 	    PUSH_STATE_GOTO(COMMIT_next, next, locinput);
8767 	    NOT_REACHED; /* NOTREACHED */
8768 
8769 	case COMMIT_next_fail:
8770 	    no_final = 1;
8771 	    /* FALLTHROUGH */
8772             sayNO;
8773             NOT_REACHED; /* NOTREACHED */
8774 
8775 	case OPFAIL:   /* (*FAIL)  */
8776             if (scan->flags)
8777                 sv_commit = MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
8778             if (logical) {
8779                 /* deal with (?(?!)X|Y) properly,
8780                  * make sure we trigger the no branch
8781                  * of the trailing IFTHEN structure*/
8782                 sw= 0;
8783                 break;
8784             } else {
8785                 sayNO;
8786             }
8787 	    NOT_REACHED; /* NOTREACHED */
8788 
8789 #define ST st->u.mark
8790         case MARKPOINT: /*  (*MARK:foo)  */
8791             ST.prev_mark = mark_state;
8792             ST.mark_name = sv_commit = sv_yes_mark
8793                 = MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
8794             mark_state = st;
8795             ST.mark_loc = locinput;
8796             PUSH_YES_STATE_GOTO(MARKPOINT_next, next, locinput);
8797             NOT_REACHED; /* NOTREACHED */
8798 
8799         case MARKPOINT_next:
8800             mark_state = ST.prev_mark;
8801             sayYES;
8802             NOT_REACHED; /* NOTREACHED */
8803 
8804         case MARKPOINT_next_fail:
8805             if (popmark && sv_eq(ST.mark_name,popmark))
8806             {
8807                 if (ST.mark_loc > startpoint)
8808 	            reginfo->cutpoint = HOPBACKc(ST.mark_loc, 1);
8809                 popmark = NULL; /* we found our mark */
8810                 sv_commit = ST.mark_name;
8811 
8812                 DEBUG_EXECUTE_r({
8813                         Perl_re_exec_indentf( aTHX_  "%sMARKPOINT: next fail: setting cutpoint to mark:%" SVf "...%s\n",
8814                             depth,
8815 		            PL_colors[4], SVfARG(sv_commit), PL_colors[5]);
8816 		});
8817             }
8818             mark_state = ST.prev_mark;
8819             sv_yes_mark = mark_state ?
8820                 mark_state->u.mark.mark_name : NULL;
8821             sayNO;
8822             NOT_REACHED; /* NOTREACHED */
8823 
8824         case SKIP:  /*  (*SKIP)  */
8825             if (!scan->flags) {
8826                 /* (*SKIP) : if we fail we cut here*/
8827                 ST.mark_name = NULL;
8828                 ST.mark_loc = locinput;
8829                 PUSH_STATE_GOTO(SKIP_next,next, locinput);
8830             } else {
8831                 /* (*SKIP:NAME) : if there is a (*MARK:NAME) fail where it was,
8832                    otherwise do nothing.  Meaning we need to scan
8833                  */
8834                 regmatch_state *cur = mark_state;
8835                 SV *find = MUTABLE_SV(rexi->data->data[ ARG( scan ) ]);
8836 
8837                 while (cur) {
8838                     if ( sv_eq( cur->u.mark.mark_name,
8839                                 find ) )
8840                     {
8841                         ST.mark_name = find;
8842                         PUSH_STATE_GOTO( SKIP_next, next, locinput);
8843                     }
8844                     cur = cur->u.mark.prev_mark;
8845                 }
8846             }
8847             /* Didn't find our (*MARK:NAME) so ignore this (*SKIP:NAME) */
8848             break;
8849 
8850 	case SKIP_next_fail:
8851 	    if (ST.mark_name) {
8852 	        /* (*CUT:NAME) - Set up to search for the name as we
8853 	           collapse the stack*/
8854 	        popmark = ST.mark_name;
8855 	    } else {
8856 	        /* (*CUT) - No name, we cut here.*/
8857 	        if (ST.mark_loc > startpoint)
8858 	            reginfo->cutpoint = HOPBACKc(ST.mark_loc, 1);
8859 	        /* but we set sv_commit to latest mark_name if there
8860 	           is one so they can test to see how things lead to this
8861 	           cut */
8862                 if (mark_state)
8863                     sv_commit=mark_state->u.mark.mark_name;
8864             }
8865             no_final = 1;
8866             sayNO;
8867             NOT_REACHED; /* NOTREACHED */
8868 #undef ST
8869 
8870         case LNBREAK: /* \R */
8871             if ((n=is_LNBREAK_safe(locinput, reginfo->strend, utf8_target))) {
8872                 locinput += n;
8873             } else
8874                 sayNO;
8875             break;
8876 
8877 	default:
8878 	    PerlIO_printf(Perl_error_log, "%" UVxf " %d\n",
8879 			  PTR2UV(scan), OP(scan));
8880 	    Perl_croak(aTHX_ "regexp memory corruption");
8881 
8882         /* this is a point to jump to in order to increment
8883          * locinput by one character */
8884           increment_locinput:
8885             assert(!NEXTCHR_IS_EOS);
8886             if (utf8_target) {
8887                 locinput += PL_utf8skip[nextchr];
8888                 /* locinput is allowed to go 1 char off the end (signifying
8889                  * EOS), but not 2+ */
8890                 if (locinput > reginfo->strend)
8891                     sayNO;
8892             }
8893             else
8894                 locinput++;
8895             break;
8896 
8897 	} /* end switch */
8898 
8899         /* switch break jumps here */
8900 	scan = next; /* prepare to execute the next op and ... */
8901 	continue;    /* ... jump back to the top, reusing st */
8902         /* NOTREACHED */
8903 
8904       push_yes_state:
8905 	/* push a state that backtracks on success */
8906 	st->u.yes.prev_yes_state = yes_state;
8907 	yes_state = st;
8908 	/* FALLTHROUGH */
8909       push_state:
8910 	/* push a new regex state, then continue at scan  */
8911 	{
8912 	    regmatch_state *newst;
8913 
8914 	    DEBUG_STACK_r({
8915 	        regmatch_state *cur = st;
8916 	        regmatch_state *curyes = yes_state;
8917 	        U32 i;
8918 	        regmatch_slab *slab = PL_regmatch_slab;
8919                 for (i = 0; i < 3 && i <= depth; cur--,i++) {
8920                     if (cur < SLAB_FIRST(slab)) {
8921                 	slab = slab->prev;
8922                 	cur = SLAB_LAST(slab);
8923                     }
8924                     Perl_re_exec_indentf( aTHX_ "%4s #%-3d %-10s %s\n",
8925                         depth,
8926                         i ? "    " : "push",
8927                         depth - i, PL_reg_name[cur->resume_state],
8928                         (curyes == cur) ? "yes" : ""
8929                     );
8930                     if (curyes == cur)
8931 	                curyes = cur->u.yes.prev_yes_state;
8932                 }
8933             } else
8934                 DEBUG_STATE_pp("push")
8935             );
8936 	    depth++;
8937 	    st->locinput = locinput;
8938 	    newst = st+1;
8939 	    if (newst >  SLAB_LAST(PL_regmatch_slab))
8940 		newst = S_push_slab(aTHX);
8941 	    PL_regmatch_state = newst;
8942 
8943 	    locinput = pushinput;
8944 	    st = newst;
8945 	    continue;
8946             /* NOTREACHED */
8947 	}
8948     }
8949 #ifdef SOLARIS_BAD_OPTIMIZER
8950 #  undef PL_charclass
8951 #endif
8952 
8953     /*
8954     * We get here only if there's trouble -- normally "case END" is
8955     * the terminating point.
8956     */
8957     Perl_croak(aTHX_ "corrupted regexp pointers");
8958     NOT_REACHED; /* NOTREACHED */
8959 
8960   yes:
8961     if (yes_state) {
8962 	/* we have successfully completed a subexpression, but we must now
8963 	 * pop to the state marked by yes_state and continue from there */
8964 	assert(st != yes_state);
8965 #ifdef DEBUGGING
8966 	while (st != yes_state) {
8967 	    st--;
8968 	    if (st < SLAB_FIRST(PL_regmatch_slab)) {
8969 		PL_regmatch_slab = PL_regmatch_slab->prev;
8970 		st = SLAB_LAST(PL_regmatch_slab);
8971 	    }
8972 	    DEBUG_STATE_r({
8973 	        if (no_final) {
8974 	            DEBUG_STATE_pp("pop (no final)");
8975 	        } else {
8976 	            DEBUG_STATE_pp("pop (yes)");
8977 	        }
8978 	    });
8979 	    depth--;
8980 	}
8981 #else
8982 	while (yes_state < SLAB_FIRST(PL_regmatch_slab)
8983 	    || yes_state > SLAB_LAST(PL_regmatch_slab))
8984 	{
8985 	    /* not in this slab, pop slab */
8986 	    depth -= (st - SLAB_FIRST(PL_regmatch_slab) + 1);
8987 	    PL_regmatch_slab = PL_regmatch_slab->prev;
8988 	    st = SLAB_LAST(PL_regmatch_slab);
8989 	}
8990 	depth -= (st - yes_state);
8991 #endif
8992 	st = yes_state;
8993 	yes_state = st->u.yes.prev_yes_state;
8994 	PL_regmatch_state = st;
8995 
8996         if (no_final)
8997             locinput= st->locinput;
8998 	state_num = st->resume_state + no_final;
8999 	goto reenter_switch;
9000     }
9001 
9002     DEBUG_EXECUTE_r(Perl_re_printf( aTHX_  "%sMatch successful!%s\n",
9003 			  PL_colors[4], PL_colors[5]));
9004 
9005     if (reginfo->info_aux_eval) {
9006 	/* each successfully executed (?{...}) block does the equivalent of
9007 	 *   local $^R = do {...}
9008 	 * When popping the save stack, all these locals would be undone;
9009 	 * bypass this by setting the outermost saved $^R to the latest
9010 	 * value */
9011         /* I dont know if this is needed or works properly now.
9012          * see code related to PL_replgv elsewhere in this file.
9013          * Yves
9014          */
9015 	if (oreplsv != GvSV(PL_replgv))
9016 	    sv_setsv(oreplsv, GvSV(PL_replgv));
9017     }
9018     result = 1;
9019     goto final_exit;
9020 
9021   no:
9022     DEBUG_EXECUTE_r(
9023         Perl_re_exec_indentf( aTHX_  "%sfailed...%s\n",
9024             depth,
9025             PL_colors[4], PL_colors[5])
9026 	);
9027 
9028   no_silent:
9029     if (no_final) {
9030         if (yes_state) {
9031             goto yes;
9032         } else {
9033             goto final_exit;
9034         }
9035     }
9036     if (depth) {
9037 	/* there's a previous state to backtrack to */
9038 	st--;
9039 	if (st < SLAB_FIRST(PL_regmatch_slab)) {
9040 	    PL_regmatch_slab = PL_regmatch_slab->prev;
9041 	    st = SLAB_LAST(PL_regmatch_slab);
9042 	}
9043 	PL_regmatch_state = st;
9044 	locinput= st->locinput;
9045 
9046 	DEBUG_STATE_pp("pop");
9047 	depth--;
9048 	if (yes_state == st)
9049 	    yes_state = st->u.yes.prev_yes_state;
9050 
9051 	state_num = st->resume_state + 1; /* failure = success + 1 */
9052         PERL_ASYNC_CHECK();
9053 	goto reenter_switch;
9054     }
9055     result = 0;
9056 
9057   final_exit:
9058     if (rex->intflags & PREGf_VERBARG_SEEN) {
9059         SV *sv_err = get_sv("REGERROR", 1);
9060         SV *sv_mrk = get_sv("REGMARK", 1);
9061         if (result) {
9062             sv_commit = &PL_sv_no;
9063             if (!sv_yes_mark)
9064                 sv_yes_mark = &PL_sv_yes;
9065         } else {
9066             if (!sv_commit)
9067                 sv_commit = &PL_sv_yes;
9068             sv_yes_mark = &PL_sv_no;
9069         }
9070         assert(sv_err);
9071         assert(sv_mrk);
9072         sv_setsv(sv_err, sv_commit);
9073         sv_setsv(sv_mrk, sv_yes_mark);
9074     }
9075 
9076 
9077     if (last_pushed_cv) {
9078 	dSP;
9079         /* see "Some notes about MULTICALL" above */
9080 	POP_MULTICALL;
9081         PERL_UNUSED_VAR(SP);
9082     }
9083     else
9084         LEAVE_SCOPE(orig_savestack_ix);
9085 
9086     assert(!result ||  locinput - reginfo->strbeg >= 0);
9087     return result ?  locinput - reginfo->strbeg : -1;
9088 }
9089 
9090 /*
9091  - regrepeat - repeatedly match something simple, report how many
9092  *
9093  * What 'simple' means is a node which can be the operand of a quantifier like
9094  * '+', or {1,3}
9095  *
9096  * startposp - pointer a pointer to the start position.  This is updated
9097  *             to point to the byte following the highest successful
9098  *             match.
9099  * p         - the regnode to be repeatedly matched against.
9100  * reginfo   - struct holding match state, such as strend
9101  * max       - maximum number of things to match.
9102  * depth     - (for debugging) backtracking depth.
9103  */
9104 STATIC I32
9105 S_regrepeat(pTHX_ regexp *prog, char **startposp, const regnode *p,
9106             regmatch_info *const reginfo, I32 max _pDEPTH)
9107 {
9108     char *scan;     /* Pointer to current position in target string */
9109     I32 c;
9110     char *loceol = reginfo->strend;   /* local version */
9111     I32 hardcount = 0;  /* How many matches so far */
9112     bool utf8_target = reginfo->is_utf8_target;
9113     unsigned int to_complement = 0;  /* Invert the result? */
9114     UV utf8_flags;
9115     _char_class_number classnum;
9116 
9117     PERL_ARGS_ASSERT_REGREPEAT;
9118 
9119     scan = *startposp;
9120     if (max == REG_INFTY)
9121 	max = I32_MAX;
9122     else if (! utf8_target && loceol - scan > max)
9123 	loceol = scan + max;
9124 
9125     /* Here, for the case of a non-UTF-8 target we have adjusted <loceol> down
9126      * to the maximum of how far we should go in it (leaving it set to the real
9127      * end, if the maximum permissible would take us beyond that).  This allows
9128      * us to make the loop exit condition that we haven't gone past <loceol> to
9129      * also mean that we haven't exceeded the max permissible count, saving a
9130      * test each time through the loop.  But it assumes that the OP matches a
9131      * single byte, which is true for most of the OPs below when applied to a
9132      * non-UTF-8 target.  Those relatively few OPs that don't have this
9133      * characteristic will have to compensate.
9134      *
9135      * There is no adjustment for UTF-8 targets, as the number of bytes per
9136      * character varies.  OPs will have to test both that the count is less
9137      * than the max permissible (using <hardcount> to keep track), and that we
9138      * are still within the bounds of the string (using <loceol>.  A few OPs
9139      * match a single byte no matter what the encoding.  They can omit the max
9140      * test if, for the UTF-8 case, they do the adjustment that was skipped
9141      * above.
9142      *
9143      * Thus, the code above sets things up for the common case; and exceptional
9144      * cases need extra work; the common case is to make sure <scan> doesn't
9145      * go past <loceol>, and for UTF-8 to also use <hardcount> to make sure the
9146      * count doesn't exceed the maximum permissible */
9147 
9148     switch (OP(p)) {
9149     case REG_ANY:
9150 	if (utf8_target) {
9151 	    while (scan < loceol && hardcount < max && *scan != '\n') {
9152 		scan += UTF8SKIP(scan);
9153 		hardcount++;
9154 	    }
9155 	} else {
9156             scan = (char *) memchr(scan, '\n', loceol - scan);
9157             if (! scan) {
9158                 scan = loceol;
9159             }
9160 	}
9161 	break;
9162     case SANY:
9163         if (utf8_target) {
9164 	    while (scan < loceol && hardcount < max) {
9165 	        scan += UTF8SKIP(scan);
9166 		hardcount++;
9167 	    }
9168 	}
9169 	else
9170 	    scan = loceol;
9171 	break;
9172     case EXACTL:
9173         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
9174         if (utf8_target && UTF8_IS_ABOVE_LATIN1(*scan)) {
9175             _CHECK_AND_OUTPUT_WIDE_LOCALE_UTF8_MSG(scan, loceol);
9176         }
9177         /* FALLTHROUGH */
9178     case EXACT:
9179         assert(STR_LEN(p) == reginfo->is_utf8_pat ? UTF8SKIP(STRING(p)) : 1);
9180 
9181 	c = (U8)*STRING(p);
9182 
9183         /* Can use a simple find if the pattern char to match on is invariant
9184          * under UTF-8, or both target and pattern aren't UTF-8.  Note that we
9185          * can use UTF8_IS_INVARIANT() even if the pattern isn't UTF-8, as it's
9186          * true iff it doesn't matter if the argument is in UTF-8 or not */
9187         if (UTF8_IS_INVARIANT(c) || (! utf8_target && ! reginfo->is_utf8_pat)) {
9188             if (utf8_target && loceol - scan > max) {
9189                 /* We didn't adjust <loceol> because is UTF-8, but ok to do so,
9190                  * since here, to match at all, 1 char == 1 byte */
9191                 loceol = scan + max;
9192             }
9193             scan = (char *) find_span_end((U8 *) scan, (U8 *) loceol, (U8) c);
9194 	}
9195 	else if (reginfo->is_utf8_pat) {
9196             if (utf8_target) {
9197                 STRLEN scan_char_len;
9198 
9199                 /* When both target and pattern are UTF-8, we have to do
9200                  * string EQ */
9201                 while (hardcount < max
9202                        && scan < loceol
9203                        && (scan_char_len = UTF8SKIP(scan)) <= STR_LEN(p)
9204                        && memEQ(scan, STRING(p), scan_char_len))
9205                 {
9206                     scan += scan_char_len;
9207                     hardcount++;
9208                 }
9209             }
9210             else if (! UTF8_IS_ABOVE_LATIN1(c)) {
9211 
9212                 /* Target isn't utf8; convert the character in the UTF-8
9213                  * pattern to non-UTF8, and do a simple find */
9214                 c = EIGHT_BIT_UTF8_TO_NATIVE(c, *(STRING(p) + 1));
9215                 scan = (char *) find_span_end((U8 *) scan, (U8 *) loceol, (U8) c);
9216             } /* else pattern char is above Latin1, can't possibly match the
9217                  non-UTF-8 target */
9218         }
9219         else {
9220 
9221             /* Here, the string must be utf8; pattern isn't, and <c> is
9222              * different in utf8 than not, so can't compare them directly.
9223              * Outside the loop, find the two utf8 bytes that represent c, and
9224              * then look for those in sequence in the utf8 string */
9225 	    U8 high = UTF8_TWO_BYTE_HI(c);
9226 	    U8 low = UTF8_TWO_BYTE_LO(c);
9227 
9228 	    while (hardcount < max
9229 		    && scan + 1 < loceol
9230 		    && UCHARAT(scan) == high
9231 		    && UCHARAT(scan + 1) == low)
9232 	    {
9233 		scan += 2;
9234 		hardcount++;
9235 	    }
9236 	}
9237 	break;
9238 
9239     case EXACTFAA_NO_TRIE: /* This node only generated for non-utf8 patterns */
9240         assert(! reginfo->is_utf8_pat);
9241         /* FALLTHROUGH */
9242     case EXACTFAA:
9243         utf8_flags = FOLDEQ_UTF8_NOMIX_ASCII;
9244 	goto do_exactf;
9245 
9246     case EXACTFL:
9247         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
9248 	utf8_flags = FOLDEQ_LOCALE;
9249 	goto do_exactf;
9250 
9251     case EXACTF:   /* This node only generated for non-utf8 patterns */
9252         assert(! reginfo->is_utf8_pat);
9253         utf8_flags = 0;
9254         goto do_exactf;
9255 
9256     case EXACTFLU8:
9257         if (! utf8_target) {
9258             break;
9259         }
9260         utf8_flags =  FOLDEQ_LOCALE | FOLDEQ_S2_ALREADY_FOLDED
9261                                     | FOLDEQ_S2_FOLDS_SANE;
9262         goto do_exactf;
9263 
9264     case EXACTFU_SS:
9265     case EXACTFU:
9266 	utf8_flags = reginfo->is_utf8_pat ? FOLDEQ_S2_ALREADY_FOLDED : 0;
9267 
9268       do_exactf: {
9269         int c1, c2;
9270         U8 c1_utf8[UTF8_MAXBYTES+1], c2_utf8[UTF8_MAXBYTES+1];
9271 
9272         assert(STR_LEN(p) == reginfo->is_utf8_pat ? UTF8SKIP(STRING(p)) : 1);
9273 
9274         if (S_setup_EXACTISH_ST_c1_c2(aTHX_ p, &c1, c1_utf8, &c2, c2_utf8,
9275                                         reginfo))
9276         {
9277             if (c1 == CHRTEST_VOID) {
9278                 /* Use full Unicode fold matching */
9279                 char *tmpeol = reginfo->strend;
9280                 STRLEN pat_len = reginfo->is_utf8_pat ? UTF8SKIP(STRING(p)) : 1;
9281                 while (hardcount < max
9282                         && foldEQ_utf8_flags(scan, &tmpeol, 0, utf8_target,
9283                                              STRING(p), NULL, pat_len,
9284                                              reginfo->is_utf8_pat, utf8_flags))
9285                 {
9286                     scan = tmpeol;
9287                     tmpeol = reginfo->strend;
9288                     hardcount++;
9289                 }
9290             }
9291             else if (utf8_target) {
9292                 if (c1 == c2) {
9293                     while (scan < loceol
9294                            && hardcount < max
9295                            && memEQ(scan, c1_utf8, UTF8SKIP(scan)))
9296                     {
9297                         scan += UTF8SKIP(scan);
9298                         hardcount++;
9299                     }
9300                 }
9301                 else {
9302                     while (scan < loceol
9303                            && hardcount < max
9304                            && (memEQ(scan, c1_utf8, UTF8SKIP(scan))
9305                                || memEQ(scan, c2_utf8, UTF8SKIP(scan))))
9306                     {
9307                         scan += UTF8SKIP(scan);
9308                         hardcount++;
9309                     }
9310                 }
9311             }
9312             else if (c1 == c2) {
9313                 scan = (char *) find_span_end((U8 *) scan, (U8 *) loceol, (U8) c1);
9314             }
9315             else {
9316                 /* See comments in regmatch() CURLY_B_min_known_fail.  We avoid
9317                  * a conditional each time through the loop if the characters
9318                  * differ only in a single bit, as is the usual situation */
9319                 U8 c1_c2_bits_differing = c1 ^ c2;
9320 
9321                 if (isPOWER_OF_2(c1_c2_bits_differing)) {
9322                     U8 c1_c2_mask = ~ c1_c2_bits_differing;
9323 
9324                     scan = (char *) find_span_end_mask((U8 *) scan,
9325                                                        (U8 *) loceol,
9326                                                        c1 & c1_c2_mask,
9327                                                        c1_c2_mask);
9328                 }
9329                 else {
9330                     while (    scan < loceol
9331                            && (UCHARAT(scan) == c1 || UCHARAT(scan) == c2))
9332                     {
9333                         scan++;
9334                     }
9335                 }
9336             }
9337 	}
9338 	break;
9339     }
9340     case ANYOFL:
9341         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
9342 
9343         if (ANYOFL_UTF8_LOCALE_REQD(FLAGS(p)) && ! IN_UTF8_CTYPE_LOCALE) {
9344             Perl_ck_warner(aTHX_ packWARN(WARN_LOCALE), utf8_locale_required);
9345         }
9346         /* FALLTHROUGH */
9347     case ANYOFD:
9348     case ANYOF:
9349 	if (utf8_target) {
9350 	    while (hardcount < max
9351                    && scan < loceol
9352 		   && reginclass(prog, p, (U8*)scan, (U8*) loceol, utf8_target))
9353 	    {
9354 		scan += UTF8SKIP(scan);
9355 		hardcount++;
9356 	    }
9357 	}
9358         else if (ANYOF_FLAGS(p)) {
9359 	    while (scan < loceol
9360                     && reginclass(prog, p, (U8*)scan, (U8*)scan+1, 0))
9361 		scan++;
9362         }
9363         else {
9364 	    while (scan < loceol && ANYOF_BITMAP_TEST(p, *((U8*)scan)))
9365 		scan++;
9366 	}
9367 	break;
9368 
9369     case ANYOFM:
9370         if (utf8_target && loceol - scan > max) {
9371 
9372             /* We didn't adjust <loceol> at the beginning of this routine
9373              * because is UTF-8, but it is actually ok to do so, since here, to
9374              * match, 1 char == 1 byte. */
9375             loceol = scan + max;
9376         }
9377 
9378         scan = (char *) find_span_end_mask((U8 *) scan, (U8 *) loceol, (U8) ARG(p), FLAGS(p));
9379         break;
9380 
9381     case ASCII:
9382         if (utf8_target && loceol - scan > max) {
9383             loceol = scan + max;
9384         }
9385 
9386         scan = find_next_non_ascii(scan, loceol, utf8_target);
9387 	break;
9388 
9389     case NASCII:
9390 	if (utf8_target) {
9391 	    while (     hardcount < max
9392                    &&   scan < loceol
9393 		   && ! isASCII_utf8_safe(scan, loceol))
9394 	    {
9395 		scan += UTF8SKIP(scan);
9396 		hardcount++;
9397 	    }
9398 	}
9399         else {
9400             scan = find_next_ascii(scan, loceol, utf8_target);
9401 	}
9402 	break;
9403 
9404     /* The argument (FLAGS) to all the POSIX node types is the class number */
9405 
9406     case NPOSIXL:
9407         to_complement = 1;
9408         /* FALLTHROUGH */
9409 
9410     case POSIXL:
9411         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
9412 	if (! utf8_target) {
9413 	    while (scan < loceol && to_complement ^ cBOOL(isFOO_lc(FLAGS(p),
9414                                                                    *scan)))
9415             {
9416 		scan++;
9417             }
9418 	} else {
9419 	    while (hardcount < max && scan < loceol
9420                    && to_complement ^ cBOOL(isFOO_utf8_lc(FLAGS(p),
9421                                                                   (U8 *) scan,
9422                                                                   (U8 *) loceol)))
9423             {
9424                 scan += UTF8SKIP(scan);
9425 		hardcount++;
9426 	    }
9427 	}
9428 	break;
9429 
9430     case POSIXD:
9431         if (utf8_target) {
9432             goto utf8_posix;
9433         }
9434         /* FALLTHROUGH */
9435 
9436     case POSIXA:
9437         if (utf8_target && loceol - scan > max) {
9438 
9439             /* We didn't adjust <loceol> at the beginning of this routine
9440              * because is UTF-8, but it is actually ok to do so, since here, to
9441              * match, 1 char == 1 byte. */
9442             loceol = scan + max;
9443         }
9444         while (scan < loceol && _generic_isCC_A((U8) *scan, FLAGS(p))) {
9445 	    scan++;
9446 	}
9447 	break;
9448 
9449     case NPOSIXD:
9450         if (utf8_target) {
9451             to_complement = 1;
9452             goto utf8_posix;
9453         }
9454         /* FALLTHROUGH */
9455 
9456     case NPOSIXA:
9457         if (! utf8_target) {
9458             while (scan < loceol && ! _generic_isCC_A((U8) *scan, FLAGS(p))) {
9459                 scan++;
9460             }
9461         }
9462         else {
9463 
9464             /* The complement of something that matches only ASCII matches all
9465              * non-ASCII, plus everything in ASCII that isn't in the class. */
9466 	    while (hardcount < max && scan < loceol
9467                    && (   ! isASCII_utf8_safe(scan, reginfo->strend)
9468                        || ! _generic_isCC_A((U8) *scan, FLAGS(p))))
9469             {
9470                 scan += UTF8SKIP(scan);
9471 		hardcount++;
9472 	    }
9473         }
9474         break;
9475 
9476     case NPOSIXU:
9477         to_complement = 1;
9478         /* FALLTHROUGH */
9479 
9480     case POSIXU:
9481 	if (! utf8_target) {
9482             while (scan < loceol && to_complement
9483                                 ^ cBOOL(_generic_isCC((U8) *scan, FLAGS(p))))
9484             {
9485                 scan++;
9486             }
9487 	}
9488 	else {
9489           utf8_posix:
9490             classnum = (_char_class_number) FLAGS(p);
9491             switch (classnum) {
9492                 default:
9493                     while (   hardcount < max && scan < loceol
9494                            && to_complement ^ cBOOL(_invlist_contains_cp(
9495                                               PL_XPosix_ptrs[classnum],
9496                                               utf8_to_uvchr_buf((U8 *) scan,
9497                                                                 (U8 *) loceol,
9498                                                                 NULL))))
9499                     {
9500                         scan += UTF8SKIP(scan);
9501                         hardcount++;
9502                     }
9503                     break;
9504 
9505                     /* For the classes below, the knowledge of how to handle
9506                      * every code point is compiled in to Perl via a macro.
9507                      * This code is written for making the loops as tight as
9508                      * possible.  It could be refactored to save space instead.
9509                      * */
9510 
9511                 case _CC_ENUM_SPACE:
9512                     while (hardcount < max
9513                            && scan < loceol
9514                            && (to_complement
9515                                ^ cBOOL(isSPACE_utf8_safe(scan, loceol))))
9516                     {
9517                         scan += UTF8SKIP(scan);
9518                         hardcount++;
9519                     }
9520                     break;
9521                 case _CC_ENUM_BLANK:
9522                     while (hardcount < max
9523                            && scan < loceol
9524                            && (to_complement
9525                                 ^ cBOOL(isBLANK_utf8_safe(scan, loceol))))
9526                     {
9527                         scan += UTF8SKIP(scan);
9528                         hardcount++;
9529                     }
9530                     break;
9531                 case _CC_ENUM_XDIGIT:
9532                     while (hardcount < max
9533                            && scan < loceol
9534                            && (to_complement
9535                                ^ cBOOL(isXDIGIT_utf8_safe(scan, loceol))))
9536                     {
9537                         scan += UTF8SKIP(scan);
9538                         hardcount++;
9539                     }
9540                     break;
9541                 case _CC_ENUM_VERTSPACE:
9542                     while (hardcount < max
9543                            && scan < loceol
9544                            && (to_complement
9545                                ^ cBOOL(isVERTWS_utf8_safe(scan, loceol))))
9546                     {
9547                         scan += UTF8SKIP(scan);
9548                         hardcount++;
9549                     }
9550                     break;
9551                 case _CC_ENUM_CNTRL:
9552                     while (hardcount < max
9553                            && scan < loceol
9554                            && (to_complement
9555                                ^ cBOOL(isCNTRL_utf8_safe(scan, loceol))))
9556                     {
9557                         scan += UTF8SKIP(scan);
9558                         hardcount++;
9559                     }
9560                     break;
9561             }
9562 	}
9563         break;
9564 
9565     case LNBREAK:
9566         if (utf8_target) {
9567 	    while (hardcount < max && scan < loceol &&
9568                     (c=is_LNBREAK_utf8_safe(scan, loceol))) {
9569 		scan += c;
9570 		hardcount++;
9571 	    }
9572 	} else {
9573             /* LNBREAK can match one or two latin chars, which is ok, but we
9574              * have to use hardcount in this situation, and throw away the
9575              * adjustment to <loceol> done before the switch statement */
9576             loceol = reginfo->strend;
9577 	    while (scan < loceol && (c=is_LNBREAK_latin1_safe(scan, loceol))) {
9578 		scan+=c;
9579 		hardcount++;
9580 	    }
9581 	}
9582 	break;
9583 
9584     case BOUNDL:
9585     case NBOUNDL:
9586         _CHECK_AND_WARN_PROBLEMATIC_LOCALE;
9587         /* FALLTHROUGH */
9588     case BOUND:
9589     case BOUNDA:
9590     case BOUNDU:
9591     case EOS:
9592     case GPOS:
9593     case KEEPS:
9594     case NBOUND:
9595     case NBOUNDA:
9596     case NBOUNDU:
9597     case OPFAIL:
9598     case SBOL:
9599     case SEOL:
9600         /* These are all 0 width, so match right here or not at all. */
9601         break;
9602 
9603     default:
9604         Perl_croak(aTHX_ "panic: regrepeat() called with unrecognized node type %d='%s'", OP(p), PL_reg_name[OP(p)]);
9605         NOT_REACHED; /* NOTREACHED */
9606 
9607     }
9608 
9609     if (hardcount)
9610 	c = hardcount;
9611     else
9612 	c = scan - *startposp;
9613     *startposp = scan;
9614 
9615     DEBUG_r({
9616 	GET_RE_DEBUG_FLAGS_DECL;
9617 	DEBUG_EXECUTE_r({
9618 	    SV * const prop = sv_newmortal();
9619             regprop(prog, prop, p, reginfo, NULL);
9620             Perl_re_exec_indentf( aTHX_  "%s can match %" IVdf " times out of %" IVdf "...\n",
9621                         depth, SvPVX_const(prop),(IV)c,(IV)max);
9622 	});
9623     });
9624 
9625     return(c);
9626 }
9627 
9628 
9629 #if !defined(PERL_IN_XSUB_RE) || defined(PLUGGABLE_RE_EXTENSION)
9630 /*
9631 - regclass_swash - prepare the utf8 swash.  Wraps the shared core version to
9632 create a copy so that changes the caller makes won't change the shared one.
9633 If <altsvp> is non-null, will return NULL in it, for back-compat.
9634  */
9635 SV *
9636 Perl_regclass_swash(pTHX_ const regexp *prog, const regnode* node, bool doinit, SV** listsvp, SV **altsvp)
9637 {
9638     PERL_ARGS_ASSERT_REGCLASS_SWASH;
9639 
9640     if (altsvp) {
9641         *altsvp = NULL;
9642     }
9643 
9644     return newSVsv(_get_regclass_nonbitmap_data(prog, node, doinit, listsvp, NULL, NULL));
9645 }
9646 
9647 #endif /* !defined(PERL_IN_XSUB_RE) || defined(PLUGGABLE_RE_EXTENSION) */
9648 
9649 /*
9650  - reginclass - determine if a character falls into a character class
9651 
9652   n is the ANYOF-type regnode
9653   p is the target string
9654   p_end points to one byte beyond the end of the target string
9655   utf8_target tells whether p is in UTF-8.
9656 
9657   Returns true if matched; false otherwise.
9658 
9659   Note that this can be a synthetic start class, a combination of various
9660   nodes, so things you think might be mutually exclusive, such as locale,
9661   aren't.  It can match both locale and non-locale
9662 
9663  */
9664 
9665 STATIC bool
9666 S_reginclass(pTHX_ regexp * const prog, const regnode * const n, const U8* const p, const U8* const p_end, const bool utf8_target)
9667 {
9668     dVAR;
9669     const char flags = ANYOF_FLAGS(n);
9670     bool match = FALSE;
9671     UV c = *p;
9672 
9673     PERL_ARGS_ASSERT_REGINCLASS;
9674 
9675     /* If c is not already the code point, get it.  Note that
9676      * UTF8_IS_INVARIANT() works even if not in UTF-8 */
9677     if (! UTF8_IS_INVARIANT(c) && utf8_target) {
9678         STRLEN c_len = 0;
9679         const U32 utf8n_flags = UTF8_ALLOW_DEFAULT;
9680 	c = utf8n_to_uvchr(p, p_end - p, &c_len, utf8n_flags | UTF8_CHECK_ONLY);
9681 	if (c_len == (STRLEN)-1) {
9682             _force_out_malformed_utf8_message(p, p_end,
9683                                               utf8n_flags,
9684                                               1 /* 1 means die */ );
9685             NOT_REACHED; /* NOTREACHED */
9686         }
9687         if (c > 255 && OP(n) == ANYOFL && ! ANYOFL_UTF8_LOCALE_REQD(flags)) {
9688             _CHECK_AND_OUTPUT_WIDE_LOCALE_CP_MSG(c);
9689         }
9690     }
9691 
9692     /* If this character is potentially in the bitmap, check it */
9693     if (c < NUM_ANYOF_CODE_POINTS) {
9694 	if (ANYOF_BITMAP_TEST(n, c))
9695 	    match = TRUE;
9696 	else if ((flags
9697                 & ANYOF_SHARED_d_MATCHES_ALL_NON_UTF8_NON_ASCII_non_d_WARN_SUPER)
9698                   && OP(n) == ANYOFD
9699 		  && ! utf8_target
9700 		  && ! isASCII(c))
9701 	{
9702 	    match = TRUE;
9703 	}
9704 	else if (flags & ANYOF_LOCALE_FLAGS) {
9705 	    if ((flags & ANYOFL_FOLD)
9706                 && c < 256
9707 		&& ANYOF_BITMAP_TEST(n, PL_fold_locale[c]))
9708             {
9709                 match = TRUE;
9710             }
9711             else if (ANYOF_POSIXL_TEST_ANY_SET(n)
9712                      && c < 256
9713             ) {
9714 
9715                 /* The data structure is arranged so bits 0, 2, 4, ... are set
9716                  * if the class includes the Posix character class given by
9717                  * bit/2; and 1, 3, 5, ... are set if the class includes the
9718                  * complemented Posix class given by int(bit/2).  So we loop
9719                  * through the bits, each time changing whether we complement
9720                  * the result or not.  Suppose for the sake of illustration
9721                  * that bits 0-3 mean respectively, \w, \W, \s, \S.  If bit 0
9722                  * is set, it means there is a match for this ANYOF node if the
9723                  * character is in the class given by the expression (0 / 2 = 0
9724                  * = \w).  If it is in that class, isFOO_lc() will return 1,
9725                  * and since 'to_complement' is 0, the result will stay TRUE,
9726                  * and we exit the loop.  Suppose instead that bit 0 is 0, but
9727                  * bit 1 is 1.  That means there is a match if the character
9728                  * matches \W.  We won't bother to call isFOO_lc() on bit 0,
9729                  * but will on bit 1.  On the second iteration 'to_complement'
9730                  * will be 1, so the exclusive or will reverse things, so we
9731                  * are testing for \W.  On the third iteration, 'to_complement'
9732                  * will be 0, and we would be testing for \s; the fourth
9733                  * iteration would test for \S, etc.
9734                  *
9735                  * Note that this code assumes that all the classes are closed
9736                  * under folding.  For example, if a character matches \w, then
9737                  * its fold does too; and vice versa.  This should be true for
9738                  * any well-behaved locale for all the currently defined Posix
9739                  * classes, except for :lower: and :upper:, which are handled
9740                  * by the pseudo-class :cased: which matches if either of the
9741                  * other two does.  To get rid of this assumption, an outer
9742                  * loop could be used below to iterate over both the source
9743                  * character, and its fold (if different) */
9744 
9745                 int count = 0;
9746                 int to_complement = 0;
9747 
9748                 while (count < ANYOF_MAX) {
9749                     if (ANYOF_POSIXL_TEST(n, count)
9750                         && to_complement ^ cBOOL(isFOO_lc(count/2, (U8) c)))
9751                     {
9752                         match = TRUE;
9753                         break;
9754                     }
9755                     count++;
9756                     to_complement ^= 1;
9757                 }
9758 	    }
9759 	}
9760     }
9761 
9762 
9763     /* If the bitmap didn't (or couldn't) match, and something outside the
9764      * bitmap could match, try that. */
9765     if (!match) {
9766 	if (c >= NUM_ANYOF_CODE_POINTS
9767             && (flags & ANYOF_MATCHES_ALL_ABOVE_BITMAP))
9768         {
9769 	    match = TRUE;	/* Everything above the bitmap matches */
9770 	}
9771             /* Here doesn't match everything above the bitmap.  If there is
9772              * some information available beyond the bitmap, we may find a
9773              * match in it.  If so, this is most likely because the code point
9774              * is outside the bitmap range.  But rarely, it could be because of
9775              * some other reason.  If so, various flags are set to indicate
9776              * this possibility.  On ANYOFD nodes, there may be matches that
9777              * happen only when the target string is UTF-8; or for other node
9778              * types, because runtime lookup is needed, regardless of the
9779              * UTF-8ness of the target string.  Finally, under /il, there may
9780              * be some matches only possible if the locale is a UTF-8 one. */
9781 	else if (    ARG(n) != ANYOF_ONLY_HAS_BITMAP
9782                  && (   c >= NUM_ANYOF_CODE_POINTS
9783                      || (   (flags & ANYOF_SHARED_d_UPPER_LATIN1_UTF8_STRING_MATCHES_non_d_RUNTIME_USER_PROP)
9784                          && (   UNLIKELY(OP(n) != ANYOFD)
9785                              || (utf8_target && ! isASCII_uni(c)
9786 #                               if NUM_ANYOF_CODE_POINTS > 256
9787                                                                  && c < 256
9788 #                               endif
9789                                 )))
9790                      || (   ANYOFL_SOME_FOLDS_ONLY_IN_UTF8_LOCALE(flags)
9791                          && IN_UTF8_CTYPE_LOCALE)))
9792         {
9793             SV* only_utf8_locale = NULL;
9794 	    SV * const sw = _get_regclass_nonbitmap_data(prog, n, TRUE, 0,
9795                                                        &only_utf8_locale, NULL);
9796 	    if (sw) {
9797                 U8 utf8_buffer[2];
9798 		U8 * utf8_p;
9799 		if (utf8_target) {
9800 		    utf8_p = (U8 *) p;
9801 		} else { /* Convert to utf8 */
9802 		    utf8_p = utf8_buffer;
9803                     append_utf8_from_native_byte(*p, &utf8_p);
9804 		    utf8_p = utf8_buffer;
9805 		}
9806 
9807 		if (swash_fetch(sw, utf8_p, TRUE)) {
9808 		    match = TRUE;
9809                 }
9810 	    }
9811             if (! match && only_utf8_locale && IN_UTF8_CTYPE_LOCALE) {
9812                 match = _invlist_contains_cp(only_utf8_locale, c);
9813             }
9814 	}
9815 
9816         if (UNICODE_IS_SUPER(c)
9817             && (flags
9818                & ANYOF_SHARED_d_MATCHES_ALL_NON_UTF8_NON_ASCII_non_d_WARN_SUPER)
9819             && OP(n) != ANYOFD
9820             && ckWARN_d(WARN_NON_UNICODE))
9821         {
9822             Perl_warner(aTHX_ packWARN(WARN_NON_UNICODE),
9823                 "Matched non-Unicode code point 0x%04" UVXf " against Unicode property; may not be portable", c);
9824         }
9825     }
9826 
9827 #if ANYOF_INVERT != 1
9828     /* Depending on compiler optimization cBOOL takes time, so if don't have to
9829      * use it, don't */
9830 #   error ANYOF_INVERT needs to be set to 1, or guarded with cBOOL below,
9831 #endif
9832 
9833     /* The xor complements the return if to invert: 1^1 = 0, 1^0 = 1 */
9834     return (flags & ANYOF_INVERT) ^ match;
9835 }
9836 
9837 STATIC U8 *
9838 S_reghop3(U8 *s, SSize_t off, const U8* lim)
9839 {
9840     /* return the position 'off' UTF-8 characters away from 's', forward if
9841      * 'off' >= 0, backwards if negative.  But don't go outside of position
9842      * 'lim', which better be < s  if off < 0 */
9843 
9844     PERL_ARGS_ASSERT_REGHOP3;
9845 
9846     if (off >= 0) {
9847 	while (off-- && s < lim) {
9848 	    /* XXX could check well-formedness here */
9849 	    U8 *new_s = s + UTF8SKIP(s);
9850             if (new_s > lim) /* lim may be in the middle of a long character */
9851                 return s;
9852             s = new_s;
9853 	}
9854     }
9855     else {
9856         while (off++ && s > lim) {
9857             s--;
9858             if (UTF8_IS_CONTINUED(*s)) {
9859                 while (s > lim && UTF8_IS_CONTINUATION(*s))
9860                     s--;
9861                 if (! UTF8_IS_START(*s)) {
9862                     Perl_croak_nocontext("Malformed UTF-8 character (fatal)");
9863                 }
9864 	    }
9865             /* XXX could check well-formedness here */
9866 	}
9867     }
9868     return s;
9869 }
9870 
9871 STATIC U8 *
9872 S_reghop4(U8 *s, SSize_t off, const U8* llim, const U8* rlim)
9873 {
9874     PERL_ARGS_ASSERT_REGHOP4;
9875 
9876     if (off >= 0) {
9877         while (off-- && s < rlim) {
9878             /* XXX could check well-formedness here */
9879             s += UTF8SKIP(s);
9880         }
9881     }
9882     else {
9883         while (off++ && s > llim) {
9884             s--;
9885             if (UTF8_IS_CONTINUED(*s)) {
9886                 while (s > llim && UTF8_IS_CONTINUATION(*s))
9887                     s--;
9888                 if (! UTF8_IS_START(*s)) {
9889                     Perl_croak_nocontext("Malformed UTF-8 character (fatal)");
9890                 }
9891             }
9892             /* XXX could check well-formedness here */
9893         }
9894     }
9895     return s;
9896 }
9897 
9898 /* like reghop3, but returns NULL on overrun, rather than returning last
9899  * char pos */
9900 
9901 STATIC U8 *
9902 S_reghopmaybe3(U8* s, SSize_t off, const U8* const lim)
9903 {
9904     PERL_ARGS_ASSERT_REGHOPMAYBE3;
9905 
9906     if (off >= 0) {
9907 	while (off-- && s < lim) {
9908 	    /* XXX could check well-formedness here */
9909 	    s += UTF8SKIP(s);
9910 	}
9911 	if (off >= 0)
9912 	    return NULL;
9913     }
9914     else {
9915         while (off++ && s > lim) {
9916             s--;
9917             if (UTF8_IS_CONTINUED(*s)) {
9918                 while (s > lim && UTF8_IS_CONTINUATION(*s))
9919                     s--;
9920                 if (! UTF8_IS_START(*s)) {
9921                     Perl_croak_nocontext("Malformed UTF-8 character (fatal)");
9922                 }
9923 	    }
9924             /* XXX could check well-formedness here */
9925 	}
9926 	if (off <= 0)
9927 	    return NULL;
9928     }
9929     return s;
9930 }
9931 
9932 
9933 /* when executing a regex that may have (?{}), extra stuff needs setting
9934    up that will be visible to the called code, even before the current
9935    match has finished. In particular:
9936 
9937    * $_ is localised to the SV currently being matched;
9938    * pos($_) is created if necessary, ready to be updated on each call-out
9939      to code;
9940    * a fake PMOP is created that can be set to PL_curpm (normally PL_curpm
9941      isn't set until the current pattern is successfully finished), so that
9942      $1 etc of the match-so-far can be seen;
9943    * save the old values of subbeg etc of the current regex, and  set then
9944      to the current string (again, this is normally only done at the end
9945      of execution)
9946 */
9947 
9948 static void
9949 S_setup_eval_state(pTHX_ regmatch_info *const reginfo)
9950 {
9951     MAGIC *mg;
9952     regexp *const rex = ReANY(reginfo->prog);
9953     regmatch_info_aux_eval *eval_state = reginfo->info_aux_eval;
9954 
9955     eval_state->rex = rex;
9956 
9957     if (reginfo->sv) {
9958         /* Make $_ available to executed code. */
9959         if (reginfo->sv != DEFSV) {
9960             SAVE_DEFSV;
9961             DEFSV_set(reginfo->sv);
9962         }
9963 
9964         if (!(mg = mg_find_mglob(reginfo->sv))) {
9965             /* prepare for quick setting of pos */
9966             mg = sv_magicext_mglob(reginfo->sv);
9967             mg->mg_len = -1;
9968         }
9969         eval_state->pos_magic = mg;
9970         eval_state->pos       = mg->mg_len;
9971         eval_state->pos_flags = mg->mg_flags;
9972     }
9973     else
9974         eval_state->pos_magic = NULL;
9975 
9976     if (!PL_reg_curpm) {
9977         /* PL_reg_curpm is a fake PMOP that we can attach the current
9978          * regex to and point PL_curpm at, so that $1 et al are visible
9979          * within a /(?{})/. It's just allocated once per interpreter the
9980          * first time its needed */
9981         Newxz(PL_reg_curpm, 1, PMOP);
9982 #ifdef USE_ITHREADS
9983         {
9984             SV* const repointer = &PL_sv_undef;
9985             /* this regexp is also owned by the new PL_reg_curpm, which
9986                will try to free it.  */
9987             av_push(PL_regex_padav, repointer);
9988             PL_reg_curpm->op_pmoffset = av_tindex(PL_regex_padav);
9989             PL_regex_pad = AvARRAY(PL_regex_padav);
9990         }
9991 #endif
9992     }
9993     SET_reg_curpm(reginfo->prog);
9994     eval_state->curpm = PL_curpm;
9995     PL_curpm_under = PL_curpm;
9996     PL_curpm = PL_reg_curpm;
9997     if (RXp_MATCH_COPIED(rex)) {
9998         /*  Here is a serious problem: we cannot rewrite subbeg,
9999             since it may be needed if this match fails.  Thus
10000             $` inside (?{}) could fail... */
10001         eval_state->subbeg     = rex->subbeg;
10002         eval_state->sublen     = rex->sublen;
10003         eval_state->suboffset  = rex->suboffset;
10004         eval_state->subcoffset = rex->subcoffset;
10005 #ifdef PERL_ANY_COW
10006         eval_state->saved_copy = rex->saved_copy;
10007 #endif
10008         RXp_MATCH_COPIED_off(rex);
10009     }
10010     else
10011         eval_state->subbeg = NULL;
10012     rex->subbeg = (char *)reginfo->strbeg;
10013     rex->suboffset = 0;
10014     rex->subcoffset = 0;
10015     rex->sublen = reginfo->strend - reginfo->strbeg;
10016 }
10017 
10018 
10019 /* destructor to clear up regmatch_info_aux and regmatch_info_aux_eval */
10020 
10021 static void
10022 S_cleanup_regmatch_info_aux(pTHX_ void *arg)
10023 {
10024     regmatch_info_aux *aux = (regmatch_info_aux *) arg;
10025     regmatch_info_aux_eval *eval_state =  aux->info_aux_eval;
10026     regmatch_slab *s;
10027 
10028     Safefree(aux->poscache);
10029 
10030     if (eval_state) {
10031 
10032         /* undo the effects of S_setup_eval_state() */
10033 
10034         if (eval_state->subbeg) {
10035             regexp * const rex = eval_state->rex;
10036             rex->subbeg     = eval_state->subbeg;
10037             rex->sublen     = eval_state->sublen;
10038             rex->suboffset  = eval_state->suboffset;
10039             rex->subcoffset = eval_state->subcoffset;
10040 #ifdef PERL_ANY_COW
10041             rex->saved_copy = eval_state->saved_copy;
10042 #endif
10043             RXp_MATCH_COPIED_on(rex);
10044         }
10045         if (eval_state->pos_magic)
10046         {
10047             eval_state->pos_magic->mg_len = eval_state->pos;
10048             eval_state->pos_magic->mg_flags =
10049                  (eval_state->pos_magic->mg_flags & ~MGf_BYTES)
10050                | (eval_state->pos_flags & MGf_BYTES);
10051         }
10052 
10053         PL_curpm = eval_state->curpm;
10054     }
10055 
10056     PL_regmatch_state = aux->old_regmatch_state;
10057     PL_regmatch_slab  = aux->old_regmatch_slab;
10058 
10059     /* free all slabs above current one - this must be the last action
10060      * of this function, as aux and eval_state are allocated within
10061      * slabs and may be freed here */
10062 
10063     s = PL_regmatch_slab->next;
10064     if (s) {
10065         PL_regmatch_slab->next = NULL;
10066         while (s) {
10067             regmatch_slab * const osl = s;
10068             s = s->next;
10069             Safefree(osl);
10070         }
10071     }
10072 }
10073 
10074 
10075 STATIC void
10076 S_to_utf8_substr(pTHX_ regexp *prog)
10077 {
10078     /* Converts substr fields in prog from bytes to UTF-8, calling fbm_compile
10079      * on the converted value */
10080 
10081     int i = 1;
10082 
10083     PERL_ARGS_ASSERT_TO_UTF8_SUBSTR;
10084 
10085     do {
10086 	if (prog->substrs->data[i].substr
10087 	    && !prog->substrs->data[i].utf8_substr) {
10088 	    SV* const sv = newSVsv(prog->substrs->data[i].substr);
10089 	    prog->substrs->data[i].utf8_substr = sv;
10090 	    sv_utf8_upgrade(sv);
10091 	    if (SvVALID(prog->substrs->data[i].substr)) {
10092 		if (SvTAIL(prog->substrs->data[i].substr)) {
10093 		    /* Trim the trailing \n that fbm_compile added last
10094 		       time.  */
10095 		    SvCUR_set(sv, SvCUR(sv) - 1);
10096 		    /* Whilst this makes the SV technically "invalid" (as its
10097 		       buffer is no longer followed by "\0") when fbm_compile()
10098 		       adds the "\n" back, a "\0" is restored.  */
10099 		    fbm_compile(sv, FBMcf_TAIL);
10100 		} else
10101 		    fbm_compile(sv, 0);
10102 	    }
10103 	    if (prog->substrs->data[i].substr == prog->check_substr)
10104 		prog->check_utf8 = sv;
10105 	}
10106     } while (i--);
10107 }
10108 
10109 STATIC bool
10110 S_to_byte_substr(pTHX_ regexp *prog)
10111 {
10112     /* Converts substr fields in prog from UTF-8 to bytes, calling fbm_compile
10113      * on the converted value; returns FALSE if can't be converted. */
10114 
10115     int i = 1;
10116 
10117     PERL_ARGS_ASSERT_TO_BYTE_SUBSTR;
10118 
10119     do {
10120 	if (prog->substrs->data[i].utf8_substr
10121 	    && !prog->substrs->data[i].substr) {
10122 	    SV* sv = newSVsv(prog->substrs->data[i].utf8_substr);
10123 	    if (! sv_utf8_downgrade(sv, TRUE)) {
10124                 return FALSE;
10125             }
10126             if (SvVALID(prog->substrs->data[i].utf8_substr)) {
10127                 if (SvTAIL(prog->substrs->data[i].utf8_substr)) {
10128                     /* Trim the trailing \n that fbm_compile added last
10129                         time.  */
10130                     SvCUR_set(sv, SvCUR(sv) - 1);
10131                     fbm_compile(sv, FBMcf_TAIL);
10132                 } else
10133                     fbm_compile(sv, 0);
10134             }
10135 	    prog->substrs->data[i].substr = sv;
10136 	    if (prog->substrs->data[i].utf8_substr == prog->check_utf8)
10137 		prog->check_substr = sv;
10138 	}
10139     } while (i--);
10140 
10141     return TRUE;
10142 }
10143 
10144 #ifndef PERL_IN_XSUB_RE
10145 
10146 bool
10147 Perl__is_grapheme(pTHX_ const U8 * strbeg, const U8 * s, const U8 * strend, const UV cp)
10148 {
10149     /* Temporary helper function for toke.c.  Verify that the code point 'cp'
10150      * is a stand-alone grapheme.  The UTF-8 for 'cp' begins at position 's' in
10151      * the larger string bounded by 'strbeg' and 'strend'.
10152      *
10153      * 'cp' needs to be assigned (if not a future version of the Unicode
10154      * Standard could make it something that combines with adjacent characters,
10155      * so code using it would then break), and there has to be a GCB break
10156      * before and after the character. */
10157 
10158     GCB_enum cp_gcb_val, prev_cp_gcb_val, next_cp_gcb_val;
10159     const U8 * prev_cp_start;
10160 
10161     PERL_ARGS_ASSERT__IS_GRAPHEME;
10162 
10163     /* Unassigned code points are forbidden */
10164     if (UNLIKELY(! ELEMENT_RANGE_MATCHES_INVLIST(
10165                                     _invlist_search(PL_Assigned_invlist, cp))))
10166     {
10167         return FALSE;
10168     }
10169 
10170     cp_gcb_val = getGCB_VAL_CP(cp);
10171 
10172     /* Find the GCB value of the previous code point in the input */
10173     prev_cp_start = utf8_hop_back(s, -1, strbeg);
10174     if (UNLIKELY(prev_cp_start == s)) {
10175         prev_cp_gcb_val = GCB_EDGE;
10176     }
10177     else {
10178         prev_cp_gcb_val = getGCB_VAL_UTF8(prev_cp_start, strend);
10179     }
10180 
10181     /* And check that is a grapheme boundary */
10182     if (! isGCB(prev_cp_gcb_val, cp_gcb_val, strbeg, s,
10183                 TRUE /* is UTF-8 encoded */ ))
10184     {
10185         return FALSE;
10186     }
10187 
10188     /* Similarly verify there is a break between the current character and the
10189      * following one */
10190     s += UTF8SKIP(s);
10191     if (s >= strend) {
10192         next_cp_gcb_val = GCB_EDGE;
10193     }
10194     else {
10195         next_cp_gcb_val = getGCB_VAL_UTF8(s, strend);
10196     }
10197 
10198     return isGCB(cp_gcb_val, next_cp_gcb_val, strbeg, s, TRUE);
10199 }
10200 
10201 /*
10202 =head1 Unicode Support
10203 
10204 =for apidoc isSCRIPT_RUN
10205 
10206 Returns a bool as to whether or not the sequence of bytes from C<s> up to but
10207 not including C<send> form a "script run".  C<utf8_target> is TRUE iff the
10208 sequence starting at C<s> is to be treated as UTF-8.  To be precise, except for
10209 two degenerate cases given below, this function returns TRUE iff all code
10210 points in it come from any combination of three "scripts" given by the Unicode
10211 "Script Extensions" property: Common, Inherited, and possibly one other.
10212 Additionally all decimal digits must come from the same consecutive sequence of
10213 10.
10214 
10215 For example, if all the characters in the sequence are Greek, or Common, or
10216 Inherited, this function will return TRUE, provided any decimal digits in it
10217 are from the same block of digits in Common.  (These are the ASCII digits
10218 "0".."9" and additionally a block for full width forms of these, and several
10219 others used in mathematical notation.)   For scripts (unlike Greek) that have
10220 their own digits defined this will accept either digits from that set or from
10221 one of the Common digit sets, but not a combination of the two.  Some scripts,
10222 such as Arabic, have more than one set of digits.  All digits must come from
10223 the same set for this function to return TRUE.
10224 
10225 C<*ret_script>, if C<ret_script> is not NULL, will on return of TRUE
10226 contain the script found, using the C<SCX_enum> typedef.  Its value will be
10227 C<SCX_INVALID> if the function returns FALSE.
10228 
10229 If the sequence is empty, TRUE is returned, but C<*ret_script> (if asked for)
10230 will be C<SCX_INVALID>.
10231 
10232 If the sequence contains a single code point which is unassigned to a character
10233 in the version of Unicode being used, the function will return TRUE, and the
10234 script will be C<SCX_Unknown>.  Any other combination of unassigned code points
10235 in the input sequence will result in the function treating the input as not
10236 being a script run.
10237 
10238 The returned script will be C<SCX_Inherited> iff all the code points in it are
10239 from the Inherited script.
10240 
10241 Otherwise, the returned script will be C<SCX_Common> iff all the code points in
10242 it are from the Inherited or Common scripts.
10243 
10244 =cut
10245 
10246 */
10247 
10248 bool
10249 Perl_isSCRIPT_RUN(pTHX_ const U8 * s, const U8 * send, const bool utf8_target)
10250 {
10251     /* Basically, it looks at each character in the sequence to see if the
10252      * above conditions are met; if not it fails.  It uses an inversion map to
10253      * find the enum corresponding to the script of each character.  But this
10254      * is complicated by the fact that a few code points can be in any of
10255      * several scripts.  The data has been constructed so that there are
10256      * additional enum values (all negative) for these situations.  The
10257      * absolute value of those is an index into another table which contains
10258      * pointers to auxiliary tables for each such situation.  Each aux array
10259      * lists all the scripts for the given situation.  There is another,
10260      * parallel, table that gives the number of entries in each aux table.
10261      * These are all defined in charclass_invlists.h */
10262 
10263     /* XXX Here are the additional things UTS 39 says could be done:
10264      *
10265      * Forbid sequences of the same nonspacing mark
10266      *
10267      * Check to see that all the characters are in the sets of exemplar
10268      * characters for at least one language in the Unicode Common Locale Data
10269      * Repository [CLDR]. */
10270 
10271     dVAR;
10272 
10273     /* Things that match /\d/u */
10274     SV * decimals_invlist = PL_XPosix_ptrs[_CC_DIGIT];
10275     UV * decimals_array = invlist_array(decimals_invlist);
10276 
10277     /* What code point is the digit '0' of the script run? (0 meaning FALSE if
10278      * not currently known) */
10279     UV zero_of_run = 0;
10280 
10281     SCX_enum script_of_run  = SCX_INVALID;   /* Illegal value */
10282     SCX_enum script_of_char = SCX_INVALID;
10283 
10284     /* If the script remains not fully determined from iteration to iteration,
10285      * this is the current intersection of the possiblities.  */
10286     SCX_enum * intersection = NULL;
10287     PERL_UINT_FAST8_T intersection_len = 0;
10288 
10289     bool retval = TRUE;
10290     SCX_enum * ret_script = NULL;
10291 
10292     assert(send >= s);
10293 
10294     PERL_ARGS_ASSERT_ISSCRIPT_RUN;
10295 
10296     /* All code points in 0..255 are either Common or Latin, so must be a
10297      * script run.  We can return immediately unless we need to know which
10298      * script it is. */
10299     if (! utf8_target && LIKELY(send > s)) {
10300         if (ret_script == NULL) {
10301             return TRUE;
10302         }
10303 
10304         /* If any character is Latin, the run is Latin */
10305         while (s < send) {
10306             if (isALPHA_L1(*s) && LIKELY(*s != MICRO_SIGN_NATIVE)) {
10307                 *ret_script = SCX_Latin;
10308                 return TRUE;
10309             }
10310         }
10311 
10312         /* Here, all are Common */
10313         *ret_script = SCX_Common;
10314         return TRUE;
10315     }
10316 
10317     /* Look at each character in the sequence */
10318     while (s < send) {
10319         /* If the current character being examined is a digit, this is the code
10320          * point of the zero for its sequence of 10 */
10321         UV zero_of_char;
10322 
10323         UV cp;
10324 
10325         /* The code allows all scripts to use the ASCII digits.  This is
10326          * because they are in the Common script.  Hence any ASCII ones found
10327          * are ok, unless and until a digit from another set has already been
10328          * encountered.  digit ranges in Common are not similarly blessed) */
10329         if (UNLIKELY(isDIGIT(*s))) {
10330             if (UNLIKELY(script_of_run == SCX_Unknown)) {
10331                 retval = FALSE;
10332                 break;
10333             }
10334             if (zero_of_run) {
10335                 if (zero_of_run != '0') {
10336                     retval = FALSE;
10337                     break;
10338                 }
10339             }
10340             else {
10341                 zero_of_run = '0';
10342             }
10343             s++;
10344             continue;
10345         }
10346 
10347         /* Here, isn't an ASCII digit.  Find the code point of the character */
10348         if (! UTF8_IS_INVARIANT(*s)) {
10349             Size_t len;
10350             cp = valid_utf8_to_uvchr((U8 *) s, &len);
10351             s += len;
10352         }
10353         else {
10354             cp = *(s++);
10355         }
10356 
10357         /* If is within the range [+0 .. +9] of the script's zero, it also is a
10358          * digit in that script.  We can skip the rest of this code for this
10359          * character. */
10360         if (UNLIKELY(   zero_of_run
10361                      && cp >= zero_of_run
10362                      && cp - zero_of_run <= 9))
10363         {
10364             continue;
10365         }
10366 
10367         /* Find the character's script.  The correct values are hard-coded here
10368          * for small-enough code points. */
10369         if (cp < 0x2B9) {   /* From inspection of Unicode db; extremely
10370                                unlikely to change */
10371             if (       cp > 255
10372                 || (   isALPHA_L1(cp)
10373                     && LIKELY(cp != MICRO_SIGN_NATIVE)))
10374             {
10375                 script_of_char = SCX_Latin;
10376             }
10377             else {
10378                 script_of_char = SCX_Common;
10379             }
10380         }
10381         else {
10382             script_of_char = _Perl_SCX_invmap[
10383                                        _invlist_search(PL_SCX_invlist, cp)];
10384         }
10385 
10386         /* We arbitrarily accept a single unassigned character, but not in
10387          * combination with anything else, and not a run of them. */
10388         if (   UNLIKELY(script_of_run == SCX_Unknown)
10389             || UNLIKELY(   script_of_run != SCX_INVALID
10390                         && script_of_char == SCX_Unknown))
10391         {
10392             retval = FALSE;
10393             break;
10394         }
10395 
10396         /* For the first character, or the run is inherited, the run's script
10397          * is set to the char's */
10398         if (   UNLIKELY(script_of_run == SCX_INVALID)
10399             || UNLIKELY(script_of_run == SCX_Inherited))
10400         {
10401             script_of_run = script_of_char;
10402         }
10403 
10404         /* For the character's script to be Unknown, it must be the first
10405          * character in the sequence (for otherwise a test above would have
10406          * prevented us from reaching here), and we have set the run's script
10407          * to it.  Nothing further to be done for this character */
10408         if (UNLIKELY(script_of_char == SCX_Unknown)) {
10409             continue;
10410         }
10411 
10412         /* We accept 'inherited' script characters currently even at the
10413          * beginning.  (We know that no characters in Inherited are digits, or
10414          * we'd have to check for that) */
10415         if (UNLIKELY(script_of_char == SCX_Inherited)) {
10416             continue;
10417         }
10418 
10419         /* If the run so far is Common, and the new character isn't, change the
10420          * run's script to that of this character */
10421         if (script_of_run == SCX_Common && script_of_char != SCX_Common) {
10422             script_of_run = script_of_char;
10423         }
10424 
10425         /* Now we can see if the script of the new character is the same as
10426          * that of the run */
10427         if (LIKELY(script_of_char == script_of_run)) {
10428             /* By far the most common case */
10429             goto scripts_match;
10430         }
10431 
10432         /* Here, the script of the run isn't Common.  But characters in Common
10433          * match any script */
10434         if (script_of_char == SCX_Common) {
10435             goto scripts_match;
10436         }
10437 
10438 #ifndef HAS_SCX_AUX_TABLES
10439 
10440         /* Too early a Unicode version to have a code point belonging to more
10441          * than one script, so, if the scripts don't exactly match, fail */
10442         PERL_UNUSED_VAR(intersection_len);
10443         retval = FALSE;
10444         break;
10445 
10446 #else
10447 
10448         /* Here there is no exact match between the character's script and the
10449          * run's.  And we've handled the special cases of scripts Unknown,
10450          * Inherited, and Common.
10451          *
10452          * Negative script numbers signify that the value may be any of several
10453          * scripts, and we need to look at auxiliary information to make our
10454          * deterimination.  But if both are non-negative, we can fail now */
10455         if (LIKELY(script_of_char >= 0)) {
10456             const SCX_enum * search_in;
10457             PERL_UINT_FAST8_T search_in_len;
10458             PERL_UINT_FAST8_T i;
10459 
10460             if (LIKELY(script_of_run >= 0)) {
10461                 retval = FALSE;
10462                 break;
10463             }
10464 
10465             /* Use the previously constructed set of possible scripts, if any.
10466              * */
10467             if (intersection) {
10468                 search_in = intersection;
10469                 search_in_len = intersection_len;
10470             }
10471             else {
10472                 search_in = SCX_AUX_TABLE_ptrs[-script_of_run];
10473                 search_in_len = SCX_AUX_TABLE_lengths[-script_of_run];
10474             }
10475 
10476             for (i = 0; i < search_in_len; i++) {
10477                 if (search_in[i] == script_of_char) {
10478                     script_of_run = script_of_char;
10479                     goto scripts_match;
10480                 }
10481             }
10482 
10483             retval = FALSE;
10484             break;
10485         }
10486         else if (LIKELY(script_of_run >= 0)) {
10487             /* script of character could be one of several, but run is a single
10488              * script */
10489             const SCX_enum * search_in = SCX_AUX_TABLE_ptrs[-script_of_char];
10490             const PERL_UINT_FAST8_T search_in_len
10491                                      = SCX_AUX_TABLE_lengths[-script_of_char];
10492             PERL_UINT_FAST8_T i;
10493 
10494             for (i = 0; i < search_in_len; i++) {
10495                 if (search_in[i] == script_of_run) {
10496                     script_of_char = script_of_run;
10497                     goto scripts_match;
10498                 }
10499             }
10500 
10501             retval = FALSE;
10502             break;
10503         }
10504         else {
10505             /* Both run and char could be in one of several scripts.  If the
10506              * intersection is empty, then this character isn't in this script
10507              * run.  Otherwise, we need to calculate the intersection to use
10508              * for future iterations of the loop, unless we are already at the
10509              * final character */
10510             const SCX_enum * search_char = SCX_AUX_TABLE_ptrs[-script_of_char];
10511             const PERL_UINT_FAST8_T char_len
10512                                       = SCX_AUX_TABLE_lengths[-script_of_char];
10513             const SCX_enum * search_run;
10514             PERL_UINT_FAST8_T run_len;
10515 
10516             SCX_enum * new_overlap = NULL;
10517             PERL_UINT_FAST8_T i, j;
10518 
10519             if (intersection) {
10520                 search_run = intersection;
10521                 run_len = intersection_len;
10522             }
10523             else {
10524                 search_run = SCX_AUX_TABLE_ptrs[-script_of_run];
10525                 run_len = SCX_AUX_TABLE_lengths[-script_of_run];
10526             }
10527 
10528             intersection_len = 0;
10529 
10530             for (i = 0; i < run_len; i++) {
10531                 for (j = 0; j < char_len; j++) {
10532                     if (search_run[i] == search_char[j]) {
10533 
10534                         /* Here, the script at i,j matches.  That means this
10535                          * character is in the run.  But continue on to find
10536                          * the complete intersection, for the next loop
10537                          * iteration, and for the digit check after it.
10538                          *
10539                          * On the first found common script, we malloc space
10540                          * for the intersection list for the worst case of the
10541                          * intersection, which is the minimum of the number of
10542                          * scripts remaining in each set. */
10543                         if (intersection_len == 0) {
10544                             Newx(new_overlap,
10545                                  MIN(run_len - i, char_len - j),
10546                                  SCX_enum);
10547                         }
10548                         new_overlap[intersection_len++] = search_run[i];
10549                     }
10550                 }
10551             }
10552 
10553             /* Here we've looked through everything.  If they have no scripts
10554              * in common, not a run */
10555             if (intersection_len == 0) {
10556                 retval = FALSE;
10557                 break;
10558             }
10559 
10560             /* If there is only a single script in common, set to that.
10561              * Otherwise, use the intersection going forward */
10562             Safefree(intersection);
10563             intersection = NULL;
10564             if (intersection_len == 1) {
10565                 script_of_run = script_of_char = new_overlap[0];
10566                 Safefree(new_overlap);
10567                 new_overlap = NULL;
10568             }
10569             else {
10570                 intersection = new_overlap;
10571             }
10572         }
10573 
10574 #endif
10575 
10576   scripts_match:
10577 
10578         /* Here, the script of the character is compatible with that of the
10579          * run.  That means that in most cases, it continues the script run.
10580          * Either it and the run match exactly, or one or both can be in any of
10581          * several scripts, and the intersection is not empty.  However, if the
10582          * character is a decimal digit, it could still mean failure if it is
10583          * from the wrong sequence of 10.  So, we need to look at if it's a
10584          * digit.  We've already handled the 10 decimal digits, and the next
10585          * lowest one is this one: */
10586         if (cp < FIRST_NON_ASCII_DECIMAL_DIGIT) {
10587             continue;   /* Not a digit; this character is part of the run */
10588         }
10589 
10590         /* If we have a definitive '0' for the script of this character, we
10591          * know that for this to be a digit, it must be in the range of +0..+9
10592          * of that zero. */
10593         if (   script_of_char >= 0
10594             && (zero_of_char = script_zeros[script_of_char]))
10595         {
10596             if (   cp < zero_of_char
10597                 || cp > zero_of_char + 9)
10598             {
10599                 continue;   /* Not a digit; this character is part of the run
10600                              */
10601             }
10602 
10603         }
10604         else {  /* Need to look up if this character is a digit or not */
10605             SSize_t index_of_zero_of_char;
10606             index_of_zero_of_char = _invlist_search(decimals_invlist, cp);
10607             if (     UNLIKELY(index_of_zero_of_char < 0)
10608                 || ! ELEMENT_RANGE_MATCHES_INVLIST(index_of_zero_of_char))
10609             {
10610                 continue;   /* Not a digit; this character is part of the run.
10611                              */
10612             }
10613 
10614             zero_of_char = decimals_array[index_of_zero_of_char];
10615         }
10616 
10617         /* Here, the character is a decimal digit, and the zero of its sequence
10618          * of 10 is in 'zero_of_char'.  If we already have a zero for this run,
10619          * they better be the same. */
10620         if (zero_of_run) {
10621             if (zero_of_run != zero_of_char) {
10622                 retval = FALSE;
10623                 break;
10624             }
10625         }
10626         else {  /* Otherwise we now have a zero for this run */
10627             zero_of_run = zero_of_char;
10628         }
10629     } /* end of looping through CLOSESR text */
10630 
10631     Safefree(intersection);
10632 
10633     if (ret_script != NULL) {
10634         if (retval) {
10635             *ret_script = script_of_run;
10636         }
10637         else {
10638             *ret_script = SCX_INVALID;
10639         }
10640     }
10641 
10642     return retval;
10643 }
10644 
10645 #endif /* ifndef PERL_IN_XSUB_RE */
10646 
10647 /*
10648  * ex: set ts=8 sts=4 sw=4 et:
10649  */
10650