xref: /netbsd-src/external/gpl3/binutils/dist/gas/expr.c (revision 6a493d6bc668897c91594964a732d38505b70cbb)
1 /* expr.c -operands, expressions-
2    Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3    1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010, 2011,
4    2012 Free Software Foundation, Inc.
5 
6    This file is part of GAS, the GNU Assembler.
7 
8    GAS is free software; you can redistribute it and/or modify
9    it under the terms of the GNU General Public License as published by
10    the Free Software Foundation; either version 3, or (at your option)
11    any later version.
12 
13    GAS is distributed in the hope that it will be useful,
14    but WITHOUT ANY WARRANTY; without even the implied warranty of
15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16    GNU General Public License for more details.
17 
18    You should have received a copy of the GNU General Public License
19    along with GAS; see the file COPYING.  If not, write to the Free
20    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
21    02110-1301, USA.  */
22 
23 /* This is really a branch office of as-read.c. I split it out to clearly
24    distinguish the world of expressions from the world of statements.
25    (It also gives smaller files to re-compile.)
26    Here, "operand"s are of expressions, not instructions.  */
27 
28 #define min(a, b)       ((a) < (b) ? (a) : (b))
29 
30 #include "as.h"
31 #include "safe-ctype.h"
32 #include "obstack.h"
33 
34 #ifdef HAVE_LIMITS_H
35 #include <limits.h>
36 #endif
37 #ifndef CHAR_BIT
38 #define CHAR_BIT 8
39 #endif
40 
41 static void floating_constant (expressionS * expressionP);
42 static valueT generic_bignum_to_int32 (void);
43 #ifdef BFD64
44 static valueT generic_bignum_to_int64 (void);
45 #endif
46 static void integer_constant (int radix, expressionS * expressionP);
47 static void mri_char_constant (expressionS *);
48 static void clean_up_expression (expressionS * expressionP);
49 static segT operand (expressionS *, enum expr_mode);
50 static operatorT operatorf (int *);
51 
52 extern const char EXP_CHARS[], FLT_CHARS[];
53 
54 /* We keep a mapping of expression symbols to file positions, so that
55    we can provide better error messages.  */
56 
57 struct expr_symbol_line {
58   struct expr_symbol_line *next;
59   symbolS *sym;
60   char *file;
61   unsigned int line;
62 };
63 
64 static struct expr_symbol_line *expr_symbol_lines;
65 
66 /* Build a dummy symbol to hold a complex expression.  This is how we
67    build expressions up out of other expressions.  The symbol is put
68    into the fake section expr_section.  */
69 
70 symbolS *
71 make_expr_symbol (expressionS *expressionP)
72 {
73   expressionS zero;
74   symbolS *symbolP;
75   struct expr_symbol_line *n;
76 
77   if (expressionP->X_op == O_symbol
78       && expressionP->X_add_number == 0)
79     return expressionP->X_add_symbol;
80 
81   if (expressionP->X_op == O_big)
82     {
83       /* This won't work, because the actual value is stored in
84 	 generic_floating_point_number or generic_bignum, and we are
85 	 going to lose it if we haven't already.  */
86       if (expressionP->X_add_number > 0)
87 	as_bad (_("bignum invalid"));
88       else
89 	as_bad (_("floating point number invalid"));
90       zero.X_op = O_constant;
91       zero.X_add_number = 0;
92       zero.X_unsigned = 0;
93       clean_up_expression (&zero);
94       expressionP = &zero;
95     }
96 
97   /* Putting constant symbols in absolute_section rather than
98      expr_section is convenient for the old a.out code, for which
99      S_GET_SEGMENT does not always retrieve the value put in by
100      S_SET_SEGMENT.  */
101   symbolP = symbol_create (FAKE_LABEL_NAME,
102 			   (expressionP->X_op == O_constant
103 			    ? absolute_section
104 			    : expressionP->X_op == O_register
105 			      ? reg_section
106 			      : expr_section),
107 			   0, &zero_address_frag);
108   symbol_set_value_expression (symbolP, expressionP);
109 
110   if (expressionP->X_op == O_constant)
111     resolve_symbol_value (symbolP);
112 
113   n = (struct expr_symbol_line *) xmalloc (sizeof *n);
114   n->sym = symbolP;
115   as_where (&n->file, &n->line);
116   n->next = expr_symbol_lines;
117   expr_symbol_lines = n;
118 
119   return symbolP;
120 }
121 
122 /* Return the file and line number for an expr symbol.  Return
123    non-zero if something was found, 0 if no information is known for
124    the symbol.  */
125 
126 int
127 expr_symbol_where (symbolS *sym, char **pfile, unsigned int *pline)
128 {
129   register struct expr_symbol_line *l;
130 
131   for (l = expr_symbol_lines; l != NULL; l = l->next)
132     {
133       if (l->sym == sym)
134 	{
135 	  *pfile = l->file;
136 	  *pline = l->line;
137 	  return 1;
138 	}
139     }
140 
141   return 0;
142 }
143 
144 /* Utilities for building expressions.
145    Since complex expressions are recorded as symbols for use in other
146    expressions these return a symbolS * and not an expressionS *.
147    These explicitly do not take an "add_number" argument.  */
148 /* ??? For completeness' sake one might want expr_build_symbol.
149    It would just return its argument.  */
150 
151 /* Build an expression for an unsigned constant.
152    The corresponding one for signed constants is missing because
153    there's currently no need for it.  One could add an unsigned_p flag
154    but that seems more clumsy.  */
155 
156 symbolS *
157 expr_build_uconstant (offsetT value)
158 {
159   expressionS e;
160 
161   e.X_op = O_constant;
162   e.X_add_number = value;
163   e.X_unsigned = 1;
164   return make_expr_symbol (&e);
165 }
166 
167 /* Build an expression for the current location ('.').  */
168 
169 symbolS *
170 expr_build_dot (void)
171 {
172   expressionS e;
173 
174   current_location (&e);
175   return symbol_clone_if_forward_ref (make_expr_symbol (&e));
176 }
177 
178 /* Build any floating-point literal here.
179    Also build any bignum literal here.  */
180 
181 /* Seems atof_machine can backscan through generic_bignum and hit whatever
182    happens to be loaded before it in memory.  And its way too complicated
183    for me to fix right.  Thus a hack.  JF:  Just make generic_bignum bigger,
184    and never write into the early words, thus they'll always be zero.
185    I hate Dean's floating-point code.  Bleh.  */
186 LITTLENUM_TYPE generic_bignum[SIZE_OF_LARGE_NUMBER + 6];
187 
188 FLONUM_TYPE generic_floating_point_number = {
189   &generic_bignum[6],		/* low.  (JF: Was 0)  */
190   &generic_bignum[SIZE_OF_LARGE_NUMBER + 6 - 1], /* high.  JF: (added +6)  */
191   0,				/* leader.  */
192   0,				/* exponent.  */
193   0				/* sign.  */
194 };
195 
196 
197 static void
198 floating_constant (expressionS *expressionP)
199 {
200   /* input_line_pointer -> floating-point constant.  */
201   int error_code;
202 
203   error_code = atof_generic (&input_line_pointer, ".", EXP_CHARS,
204 			     &generic_floating_point_number);
205 
206   if (error_code)
207     {
208       if (error_code == ERROR_EXPONENT_OVERFLOW)
209 	{
210 	  as_bad (_("bad floating-point constant: exponent overflow"));
211 	}
212       else
213 	{
214 	  as_bad (_("bad floating-point constant: unknown error code=%d"),
215 		  error_code);
216 	}
217     }
218   expressionP->X_op = O_big;
219   /* input_line_pointer -> just after constant, which may point to
220      whitespace.  */
221   expressionP->X_add_number = -1;
222 }
223 
224 static valueT
225 generic_bignum_to_int32 (void)
226 {
227   valueT number =
228 	   ((generic_bignum[1] & LITTLENUM_MASK) << LITTLENUM_NUMBER_OF_BITS)
229 	   | (generic_bignum[0] & LITTLENUM_MASK);
230   number &= 0xffffffff;
231   return number;
232 }
233 
234 #ifdef BFD64
235 static valueT
236 generic_bignum_to_int64 (void)
237 {
238   valueT number =
239     ((((((((valueT) generic_bignum[3] & LITTLENUM_MASK)
240 	  << LITTLENUM_NUMBER_OF_BITS)
241 	 | ((valueT) generic_bignum[2] & LITTLENUM_MASK))
242 	<< LITTLENUM_NUMBER_OF_BITS)
243        | ((valueT) generic_bignum[1] & LITTLENUM_MASK))
244       << LITTLENUM_NUMBER_OF_BITS)
245      | ((valueT) generic_bignum[0] & LITTLENUM_MASK));
246   return number;
247 }
248 #endif
249 
250 static void
251 integer_constant (int radix, expressionS *expressionP)
252 {
253   char *start;		/* Start of number.  */
254   char *suffix = NULL;
255   char c;
256   valueT number;	/* Offset or (absolute) value.  */
257   short int digit;	/* Value of next digit in current radix.  */
258   short int maxdig = 0;	/* Highest permitted digit value.  */
259   int too_many_digits = 0;	/* If we see >= this number of.  */
260   char *name;		/* Points to name of symbol.  */
261   symbolS *symbolP;	/* Points to symbol.  */
262 
263   int small;			/* True if fits in 32 bits.  */
264 
265   /* May be bignum, or may fit in 32 bits.  */
266   /* Most numbers fit into 32 bits, and we want this case to be fast.
267      so we pretend it will fit into 32 bits.  If, after making up a 32
268      bit number, we realise that we have scanned more digits than
269      comfortably fit into 32 bits, we re-scan the digits coding them
270      into a bignum.  For decimal and octal numbers we are
271      conservative: Some numbers may be assumed bignums when in fact
272      they do fit into 32 bits.  Numbers of any radix can have excess
273      leading zeros: We strive to recognise this and cast them back
274      into 32 bits.  We must check that the bignum really is more than
275      32 bits, and change it back to a 32-bit number if it fits.  The
276      number we are looking for is expected to be positive, but if it
277      fits into 32 bits as an unsigned number, we let it be a 32-bit
278      number.  The cavalier approach is for speed in ordinary cases.  */
279   /* This has been extended for 64 bits.  We blindly assume that if
280      you're compiling in 64-bit mode, the target is a 64-bit machine.
281      This should be cleaned up.  */
282 
283 #ifdef BFD64
284 #define valuesize 64
285 #else /* includes non-bfd case, mostly */
286 #define valuesize 32
287 #endif
288 
289   if ((NUMBERS_WITH_SUFFIX || flag_m68k_mri) && radix == 0)
290     {
291       int flt = 0;
292 
293       /* In MRI mode, the number may have a suffix indicating the
294 	 radix.  For that matter, it might actually be a floating
295 	 point constant.  */
296       for (suffix = input_line_pointer; ISALNUM (*suffix); suffix++)
297 	{
298 	  if (*suffix == 'e' || *suffix == 'E')
299 	    flt = 1;
300 	}
301 
302       if (suffix == input_line_pointer)
303 	{
304 	  radix = 10;
305 	  suffix = NULL;
306 	}
307       else
308 	{
309 	  c = *--suffix;
310 	  c = TOUPPER (c);
311 	  /* If we have both NUMBERS_WITH_SUFFIX and LOCAL_LABELS_FB,
312 	     we distinguish between 'B' and 'b'.  This is the case for
313 	     Z80.  */
314 	  if ((NUMBERS_WITH_SUFFIX && LOCAL_LABELS_FB ? *suffix : c) == 'B')
315 	    radix = 2;
316 	  else if (c == 'D')
317 	    radix = 10;
318 	  else if (c == 'O' || c == 'Q')
319 	    radix = 8;
320 	  else if (c == 'H')
321 	    radix = 16;
322 	  else if (suffix[1] == '.' || c == 'E' || flt)
323 	    {
324 	      floating_constant (expressionP);
325 	      return;
326 	    }
327 	  else
328 	    {
329 	      radix = 10;
330 	      suffix = NULL;
331 	    }
332 	}
333     }
334 
335   switch (radix)
336     {
337     case 2:
338       maxdig = 2;
339       too_many_digits = valuesize + 1;
340       break;
341     case 8:
342       maxdig = radix = 8;
343       too_many_digits = (valuesize + 2) / 3 + 1;
344       break;
345     case 16:
346       maxdig = radix = 16;
347       too_many_digits = (valuesize + 3) / 4 + 1;
348       break;
349     case 10:
350       maxdig = radix = 10;
351       too_many_digits = (valuesize + 11) / 4; /* Very rough.  */
352     }
353 #undef valuesize
354   start = input_line_pointer;
355   c = *input_line_pointer++;
356   for (number = 0;
357        (digit = hex_value (c)) < maxdig;
358        c = *input_line_pointer++)
359     {
360       number = number * radix + digit;
361     }
362   /* c contains character after number.  */
363   /* input_line_pointer->char after c.  */
364   small = (input_line_pointer - start - 1) < too_many_digits;
365 
366   if (radix == 16 && c == '_')
367     {
368       /* This is literal of the form 0x333_0_12345678_1.
369 	 This example is equivalent to 0x00000333000000001234567800000001.  */
370 
371       int num_little_digits = 0;
372       int i;
373       input_line_pointer = start;	/* -> 1st digit.  */
374 
375       know (LITTLENUM_NUMBER_OF_BITS == 16);
376 
377       for (c = '_'; c == '_'; num_little_digits += 2)
378 	{
379 
380 	  /* Convert one 64-bit word.  */
381 	  int ndigit = 0;
382 	  number = 0;
383 	  for (c = *input_line_pointer++;
384 	       (digit = hex_value (c)) < maxdig;
385 	       c = *(input_line_pointer++))
386 	    {
387 	      number = number * radix + digit;
388 	      ndigit++;
389 	    }
390 
391 	  /* Check for 8 digit per word max.  */
392 	  if (ndigit > 8)
393 	    as_bad (_("a bignum with underscores may not have more than 8 hex digits in any word"));
394 
395 	  /* Add this chunk to the bignum.
396 	     Shift things down 2 little digits.  */
397 	  know (LITTLENUM_NUMBER_OF_BITS == 16);
398 	  for (i = min (num_little_digits + 1, SIZE_OF_LARGE_NUMBER - 1);
399 	       i >= 2;
400 	       i--)
401 	    generic_bignum[i] = generic_bignum[i - 2];
402 
403 	  /* Add the new digits as the least significant new ones.  */
404 	  generic_bignum[0] = number & 0xffffffff;
405 	  generic_bignum[1] = number >> 16;
406 	}
407 
408       /* Again, c is char after number, input_line_pointer->after c.  */
409 
410       if (num_little_digits > SIZE_OF_LARGE_NUMBER - 1)
411 	num_little_digits = SIZE_OF_LARGE_NUMBER - 1;
412 
413       gas_assert (num_little_digits >= 4);
414 
415       if (num_little_digits != 8)
416 	as_bad (_("a bignum with underscores must have exactly 4 words"));
417 
418       /* We might have some leading zeros.  These can be trimmed to give
419 	 us a change to fit this constant into a small number.  */
420       while (generic_bignum[num_little_digits - 1] == 0
421 	     && num_little_digits > 1)
422 	num_little_digits--;
423 
424       if (num_little_digits <= 2)
425 	{
426 	  /* will fit into 32 bits.  */
427 	  number = generic_bignum_to_int32 ();
428 	  small = 1;
429 	}
430 #ifdef BFD64
431       else if (num_little_digits <= 4)
432 	{
433 	  /* Will fit into 64 bits.  */
434 	  number = generic_bignum_to_int64 ();
435 	  small = 1;
436 	}
437 #endif
438       else
439 	{
440 	  small = 0;
441 
442 	  /* Number of littlenums in the bignum.  */
443 	  number = num_little_digits;
444 	}
445     }
446   else if (!small)
447     {
448       /* We saw a lot of digits. manufacture a bignum the hard way.  */
449       LITTLENUM_TYPE *leader;	/* -> high order littlenum of the bignum.  */
450       LITTLENUM_TYPE *pointer;	/* -> littlenum we are frobbing now.  */
451       long carry;
452 
453       leader = generic_bignum;
454       generic_bignum[0] = 0;
455       generic_bignum[1] = 0;
456       generic_bignum[2] = 0;
457       generic_bignum[3] = 0;
458       input_line_pointer = start;	/* -> 1st digit.  */
459       c = *input_line_pointer++;
460       for (; (carry = hex_value (c)) < maxdig; c = *input_line_pointer++)
461 	{
462 	  for (pointer = generic_bignum; pointer <= leader; pointer++)
463 	    {
464 	      long work;
465 
466 	      work = carry + radix * *pointer;
467 	      *pointer = work & LITTLENUM_MASK;
468 	      carry = work >> LITTLENUM_NUMBER_OF_BITS;
469 	    }
470 	  if (carry)
471 	    {
472 	      if (leader < generic_bignum + SIZE_OF_LARGE_NUMBER - 1)
473 		{
474 		  /* Room to grow a longer bignum.  */
475 		  *++leader = carry;
476 		}
477 	    }
478 	}
479       /* Again, c is char after number.  */
480       /* input_line_pointer -> after c.  */
481       know (LITTLENUM_NUMBER_OF_BITS == 16);
482       if (leader < generic_bignum + 2)
483 	{
484 	  /* Will fit into 32 bits.  */
485 	  number = generic_bignum_to_int32 ();
486 	  small = 1;
487 	}
488 #ifdef BFD64
489       else if (leader < generic_bignum + 4)
490 	{
491 	  /* Will fit into 64 bits.  */
492 	  number = generic_bignum_to_int64 ();
493 	  small = 1;
494 	}
495 #endif
496       else
497 	{
498 	  /* Number of littlenums in the bignum.  */
499 	  number = leader - generic_bignum + 1;
500 	}
501     }
502 
503   if ((NUMBERS_WITH_SUFFIX || flag_m68k_mri)
504       && suffix != NULL
505       && input_line_pointer - 1 == suffix)
506     c = *input_line_pointer++;
507 
508   if (small)
509     {
510       /* Here with number, in correct radix. c is the next char.
511 	 Note that unlike un*x, we allow "011f" "0x9f" to both mean
512 	 the same as the (conventional) "9f".
513 	 This is simply easier than checking for strict canonical
514 	 form.  Syntax sux!  */
515 
516       if (LOCAL_LABELS_FB && c == 'b')
517 	{
518 	  /* Backward ref to local label.
519 	     Because it is backward, expect it to be defined.  */
520 	  /* Construct a local label.  */
521 	  name = fb_label_name ((int) number, 0);
522 
523 	  /* Seen before, or symbol is defined: OK.  */
524 	  symbolP = symbol_find (name);
525 	  if ((symbolP != NULL) && (S_IS_DEFINED (symbolP)))
526 	    {
527 	      /* Local labels are never absolute.  Don't waste time
528 		 checking absoluteness.  */
529 	      know (SEG_NORMAL (S_GET_SEGMENT (symbolP)));
530 
531 	      expressionP->X_op = O_symbol;
532 	      expressionP->X_add_symbol = symbolP;
533 	    }
534 	  else
535 	    {
536 	      /* Either not seen or not defined.  */
537 	      /* @@ Should print out the original string instead of
538 		 the parsed number.  */
539 	      as_bad (_("backward ref to unknown label \"%d:\""),
540 		      (int) number);
541 	      expressionP->X_op = O_constant;
542 	    }
543 
544 	  expressionP->X_add_number = 0;
545 	}			/* case 'b' */
546       else if (LOCAL_LABELS_FB && c == 'f')
547 	{
548 	  /* Forward reference.  Expect symbol to be undefined or
549 	     unknown.  undefined: seen it before.  unknown: never seen
550 	     it before.
551 
552 	     Construct a local label name, then an undefined symbol.
553 	     Don't create a xseg frag for it: caller may do that.
554 	     Just return it as never seen before.  */
555 	  name = fb_label_name ((int) number, 1);
556 	  symbolP = symbol_find_or_make (name);
557 	  /* We have no need to check symbol properties.  */
558 #ifndef many_segments
559 	  /* Since "know" puts its arg into a "string", we
560 	     can't have newlines in the argument.  */
561 	  know (S_GET_SEGMENT (symbolP) == undefined_section || S_GET_SEGMENT (symbolP) == text_section || S_GET_SEGMENT (symbolP) == data_section);
562 #endif
563 	  expressionP->X_op = O_symbol;
564 	  expressionP->X_add_symbol = symbolP;
565 	  expressionP->X_add_number = 0;
566 	}			/* case 'f' */
567       else if (LOCAL_LABELS_DOLLAR && c == '$')
568 	{
569 	  /* If the dollar label is *currently* defined, then this is just
570 	     another reference to it.  If it is not *currently* defined,
571 	     then this is a fresh instantiation of that number, so create
572 	     it.  */
573 
574 	  if (dollar_label_defined ((long) number))
575 	    {
576 	      name = dollar_label_name ((long) number, 0);
577 	      symbolP = symbol_find (name);
578 	      know (symbolP != NULL);
579 	    }
580 	  else
581 	    {
582 	      name = dollar_label_name ((long) number, 1);
583 	      symbolP = symbol_find_or_make (name);
584 	    }
585 
586 	  expressionP->X_op = O_symbol;
587 	  expressionP->X_add_symbol = symbolP;
588 	  expressionP->X_add_number = 0;
589 	}			/* case '$' */
590       else
591 	{
592 	  expressionP->X_op = O_constant;
593 	  expressionP->X_add_number = number;
594 	  input_line_pointer--;	/* Restore following character.  */
595 	}			/* Really just a number.  */
596     }
597   else
598     {
599       /* Not a small number.  */
600       expressionP->X_op = O_big;
601       expressionP->X_add_number = number;	/* Number of littlenums.  */
602       input_line_pointer--;	/* -> char following number.  */
603     }
604 }
605 
606 /* Parse an MRI multi character constant.  */
607 
608 static void
609 mri_char_constant (expressionS *expressionP)
610 {
611   int i;
612 
613   if (*input_line_pointer == '\''
614       && input_line_pointer[1] != '\'')
615     {
616       expressionP->X_op = O_constant;
617       expressionP->X_add_number = 0;
618       return;
619     }
620 
621   /* In order to get the correct byte ordering, we must build the
622      number in reverse.  */
623   for (i = SIZE_OF_LARGE_NUMBER - 1; i >= 0; i--)
624     {
625       int j;
626 
627       generic_bignum[i] = 0;
628       for (j = 0; j < CHARS_PER_LITTLENUM; j++)
629 	{
630 	  if (*input_line_pointer == '\'')
631 	    {
632 	      if (input_line_pointer[1] != '\'')
633 		break;
634 	      ++input_line_pointer;
635 	    }
636 	  generic_bignum[i] <<= 8;
637 	  generic_bignum[i] += *input_line_pointer;
638 	  ++input_line_pointer;
639 	}
640 
641       if (i < SIZE_OF_LARGE_NUMBER - 1)
642 	{
643 	  /* If there is more than one littlenum, left justify the
644 	     last one to make it match the earlier ones.  If there is
645 	     only one, we can just use the value directly.  */
646 	  for (; j < CHARS_PER_LITTLENUM; j++)
647 	    generic_bignum[i] <<= 8;
648 	}
649 
650       if (*input_line_pointer == '\''
651 	  && input_line_pointer[1] != '\'')
652 	break;
653     }
654 
655   if (i < 0)
656     {
657       as_bad (_("character constant too large"));
658       i = 0;
659     }
660 
661   if (i > 0)
662     {
663       int c;
664       int j;
665 
666       c = SIZE_OF_LARGE_NUMBER - i;
667       for (j = 0; j < c; j++)
668 	generic_bignum[j] = generic_bignum[i + j];
669       i = c;
670     }
671 
672   know (LITTLENUM_NUMBER_OF_BITS == 16);
673   if (i > 2)
674     {
675       expressionP->X_op = O_big;
676       expressionP->X_add_number = i;
677     }
678   else
679     {
680       expressionP->X_op = O_constant;
681       if (i < 2)
682 	expressionP->X_add_number = generic_bignum[0] & LITTLENUM_MASK;
683       else
684 	expressionP->X_add_number =
685 	  (((generic_bignum[1] & LITTLENUM_MASK)
686 	    << LITTLENUM_NUMBER_OF_BITS)
687 	   | (generic_bignum[0] & LITTLENUM_MASK));
688     }
689 
690   /* Skip the final closing quote.  */
691   ++input_line_pointer;
692 }
693 
694 /* Return an expression representing the current location.  This
695    handles the magic symbol `.'.  */
696 
697 void
698 current_location (expressionS *expressionp)
699 {
700   if (now_seg == absolute_section)
701     {
702       expressionp->X_op = O_constant;
703       expressionp->X_add_number = abs_section_offset;
704     }
705   else
706     {
707       expressionp->X_op = O_symbol;
708       expressionp->X_add_symbol = &dot_symbol;
709       expressionp->X_add_number = 0;
710     }
711 }
712 
713 /* In:	Input_line_pointer points to 1st char of operand, which may
714 	be a space.
715 
716    Out:	An expressionS.
717 	The operand may have been empty: in this case X_op == O_absent.
718 	Input_line_pointer->(next non-blank) char after operand.  */
719 
720 static segT
721 operand (expressionS *expressionP, enum expr_mode mode)
722 {
723   char c;
724   symbolS *symbolP;	/* Points to symbol.  */
725   char *name;		/* Points to name of symbol.  */
726   segT segment;
727 
728   /* All integers are regarded as unsigned unless they are negated.
729      This is because the only thing which cares whether a number is
730      unsigned is the code in emit_expr which extends constants into
731      bignums.  It should only sign extend negative numbers, so that
732      something like ``.quad 0x80000000'' is not sign extended even
733      though it appears negative if valueT is 32 bits.  */
734   expressionP->X_unsigned = 1;
735 
736   /* Digits, assume it is a bignum.  */
737 
738   SKIP_WHITESPACE ();		/* Leading whitespace is part of operand.  */
739   c = *input_line_pointer++;	/* input_line_pointer -> past char in c.  */
740 
741   if (is_end_of_line[(unsigned char) c])
742     goto eol;
743 
744   switch (c)
745     {
746     case '1':
747     case '2':
748     case '3':
749     case '4':
750     case '5':
751     case '6':
752     case '7':
753     case '8':
754     case '9':
755       input_line_pointer--;
756 
757       integer_constant ((NUMBERS_WITH_SUFFIX || flag_m68k_mri)
758 			? 0 : 10,
759 			expressionP);
760       break;
761 
762 #ifdef LITERAL_PREFIXDOLLAR_HEX
763     case '$':
764       /* $L is the start of a local label, not a hex constant.  */
765       if (* input_line_pointer == 'L')
766       goto isname;
767       integer_constant (16, expressionP);
768       break;
769 #endif
770 
771 #ifdef LITERAL_PREFIXPERCENT_BIN
772     case '%':
773       integer_constant (2, expressionP);
774       break;
775 #endif
776 
777     case '0':
778       /* Non-decimal radix.  */
779 
780       if (NUMBERS_WITH_SUFFIX || flag_m68k_mri)
781 	{
782 	  char *s;
783 
784 	  /* Check for a hex or float constant.  */
785 	  for (s = input_line_pointer; hex_p (*s); s++)
786 	    ;
787 	  if (*s == 'h' || *s == 'H' || *input_line_pointer == '.')
788 	    {
789 	      --input_line_pointer;
790 	      integer_constant (0, expressionP);
791 	      break;
792 	    }
793 	}
794       c = *input_line_pointer;
795       switch (c)
796 	{
797 	case 'o':
798 	case 'O':
799 	case 'q':
800 	case 'Q':
801 	case '8':
802 	case '9':
803 	  if (NUMBERS_WITH_SUFFIX || flag_m68k_mri)
804 	    {
805 	      integer_constant (0, expressionP);
806 	      break;
807 	    }
808 	  /* Fall through.  */
809 	default:
810 	default_case:
811 	  if (c && strchr (FLT_CHARS, c))
812 	    {
813 	      input_line_pointer++;
814 	      floating_constant (expressionP);
815 	      expressionP->X_add_number = - TOLOWER (c);
816 	    }
817 	  else
818 	    {
819 	      /* The string was only zero.  */
820 	      expressionP->X_op = O_constant;
821 	      expressionP->X_add_number = 0;
822 	    }
823 
824 	  break;
825 
826 	case 'x':
827 	case 'X':
828 	  if (flag_m68k_mri)
829 	    goto default_case;
830 	  input_line_pointer++;
831 	  integer_constant (16, expressionP);
832 	  break;
833 
834 	case 'b':
835 	  if (LOCAL_LABELS_FB && ! (flag_m68k_mri || NUMBERS_WITH_SUFFIX))
836 	    {
837 	      /* This code used to check for '+' and '-' here, and, in
838 		 some conditions, fall through to call
839 		 integer_constant.  However, that didn't make sense,
840 		 as integer_constant only accepts digits.  */
841 	      /* Some of our code elsewhere does permit digits greater
842 		 than the expected base; for consistency, do the same
843 		 here.  */
844 	      if (input_line_pointer[1] < '0'
845 		  || input_line_pointer[1] > '9')
846 		{
847 		  /* Parse this as a back reference to label 0.  */
848 		  input_line_pointer--;
849 		  integer_constant (10, expressionP);
850 		  break;
851 		}
852 	      /* Otherwise, parse this as a binary number.  */
853 	    }
854 	  /* Fall through.  */
855 	case 'B':
856 	  input_line_pointer++;
857 	  if (flag_m68k_mri || NUMBERS_WITH_SUFFIX)
858 	    goto default_case;
859 	  integer_constant (2, expressionP);
860 	  break;
861 
862 	case '0':
863 	case '1':
864 	case '2':
865 	case '3':
866 	case '4':
867 	case '5':
868 	case '6':
869 	case '7':
870 	  integer_constant ((flag_m68k_mri || NUMBERS_WITH_SUFFIX)
871 			    ? 0 : 8,
872 			    expressionP);
873 	  break;
874 
875 	case 'f':
876 	  if (LOCAL_LABELS_FB)
877 	    {
878 	      /* If it says "0f" and it could possibly be a floating point
879 		 number, make it one.  Otherwise, make it a local label,
880 		 and try to deal with parsing the rest later.  */
881 	      if (!input_line_pointer[1]
882 		  || (is_end_of_line[0xff & input_line_pointer[1]])
883 		  || strchr (FLT_CHARS, 'f') == NULL)
884 		goto is_0f_label;
885 	      {
886 		char *cp = input_line_pointer + 1;
887 		int r = atof_generic (&cp, ".", EXP_CHARS,
888 				      &generic_floating_point_number);
889 		switch (r)
890 		  {
891 		  case 0:
892 		  case ERROR_EXPONENT_OVERFLOW:
893 		    if (*cp == 'f' || *cp == 'b')
894 		      /* Looks like a difference expression.  */
895 		      goto is_0f_label;
896 		    else if (cp == input_line_pointer + 1)
897 		      /* No characters has been accepted -- looks like
898 			 end of operand.  */
899 		      goto is_0f_label;
900 		    else
901 		      goto is_0f_float;
902 		  default:
903 		    as_fatal (_("expr.c(operand): bad atof_generic return val %d"),
904 			      r);
905 		  }
906 	      }
907 
908 	      /* Okay, now we've sorted it out.  We resume at one of these
909 		 two labels, depending on what we've decided we're probably
910 		 looking at.  */
911 	    is_0f_label:
912 	      input_line_pointer--;
913 	      integer_constant (10, expressionP);
914 	      break;
915 
916 	    is_0f_float:
917 	      /* Fall through.  */
918 	      ;
919 	    }
920 
921 	case 'd':
922 	case 'D':
923 	  if (flag_m68k_mri || NUMBERS_WITH_SUFFIX)
924 	    {
925 	      integer_constant (0, expressionP);
926 	      break;
927 	    }
928 	  /* Fall through.  */
929 	case 'F':
930 	case 'r':
931 	case 'e':
932 	case 'E':
933 	case 'g':
934 	case 'G':
935 	  input_line_pointer++;
936 	  floating_constant (expressionP);
937 	  expressionP->X_add_number = - TOLOWER (c);
938 	  break;
939 
940 	case '$':
941 	  if (LOCAL_LABELS_DOLLAR)
942 	    {
943 	      integer_constant (10, expressionP);
944 	      break;
945 	    }
946 	  else
947 	    goto default_case;
948 	}
949 
950       break;
951 
952 #ifndef NEED_INDEX_OPERATOR
953     case '[':
954 # ifdef md_need_index_operator
955       if (md_need_index_operator())
956 	goto de_fault;
957 # endif
958       /* FALLTHROUGH */
959 #endif
960     case '(':
961       /* Didn't begin with digit & not a name.  */
962       segment = expr (0, expressionP, mode);
963       /* expression () will pass trailing whitespace.  */
964       if ((c == '(' && *input_line_pointer != ')')
965 	  || (c == '[' && *input_line_pointer != ']'))
966 	as_bad (_("missing '%c'"), c == '(' ? ')' : ']');
967       else
968 	input_line_pointer++;
969       SKIP_WHITESPACE ();
970       /* Here with input_line_pointer -> char after "(...)".  */
971       return segment;
972 
973 #ifdef TC_M68K
974     case 'E':
975       if (! flag_m68k_mri || *input_line_pointer != '\'')
976 	goto de_fault;
977       as_bad (_("EBCDIC constants are not supported"));
978       /* Fall through.  */
979     case 'A':
980       if (! flag_m68k_mri || *input_line_pointer != '\'')
981 	goto de_fault;
982       ++input_line_pointer;
983       /* Fall through.  */
984 #endif
985     case '\'':
986       if (! flag_m68k_mri)
987 	{
988 	  /* Warning: to conform to other people's assemblers NO
989 	     ESCAPEMENT is permitted for a single quote.  The next
990 	     character, parity errors and all, is taken as the value
991 	     of the operand.  VERY KINKY.  */
992 	  expressionP->X_op = O_constant;
993 	  expressionP->X_add_number = *input_line_pointer++;
994 	  break;
995 	}
996 
997       mri_char_constant (expressionP);
998       break;
999 
1000 #ifdef TC_M68K
1001     case '"':
1002       /* Double quote is the bitwise not operator in MRI mode.  */
1003       if (! flag_m68k_mri)
1004 	goto de_fault;
1005       /* Fall through.  */
1006 #endif
1007     case '~':
1008       /* '~' is permitted to start a label on the Delta.  */
1009       if (is_name_beginner (c))
1010 	goto isname;
1011     case '!':
1012     case '-':
1013     case '+':
1014       {
1015 #ifdef md_operator
1016       unary:
1017 #endif
1018 	operand (expressionP, mode);
1019 	if (expressionP->X_op == O_constant)
1020 	  {
1021 	    /* input_line_pointer -> char after operand.  */
1022 	    if (c == '-')
1023 	      {
1024 		expressionP->X_add_number = - expressionP->X_add_number;
1025 		/* Notice: '-' may overflow: no warning is given.
1026 		   This is compatible with other people's
1027 		   assemblers.  Sigh.  */
1028 		expressionP->X_unsigned = 0;
1029 	      }
1030 	    else if (c == '~' || c == '"')
1031 	      expressionP->X_add_number = ~ expressionP->X_add_number;
1032 	    else if (c == '!')
1033 	      expressionP->X_add_number = ! expressionP->X_add_number;
1034 	  }
1035 	else if (expressionP->X_op == O_big
1036 		 && expressionP->X_add_number <= 0
1037 		 && c == '-'
1038 		 && (generic_floating_point_number.sign == '+'
1039 		     || generic_floating_point_number.sign == 'P'))
1040 	  {
1041 	    /* Negative flonum (eg, -1.000e0).  */
1042 	    if (generic_floating_point_number.sign == '+')
1043 	      generic_floating_point_number.sign = '-';
1044 	    else
1045 	      generic_floating_point_number.sign = 'N';
1046 	  }
1047 	else if (expressionP->X_op == O_big
1048 		 && expressionP->X_add_number > 0)
1049 	  {
1050 	    int i;
1051 
1052 	    if (c == '~' || c == '-')
1053 	      {
1054 		for (i = 0; i < expressionP->X_add_number; ++i)
1055 		  generic_bignum[i] = ~generic_bignum[i];
1056 
1057 		/* Extend the bignum to at least the size of .octa.  */
1058 		if (expressionP->X_add_number < SIZE_OF_LARGE_NUMBER)
1059 		  {
1060 		    expressionP->X_add_number = SIZE_OF_LARGE_NUMBER;
1061 		    for (; i < expressionP->X_add_number; ++i)
1062 		      generic_bignum[i] = ~(LITTLENUM_TYPE) 0;
1063 		  }
1064 
1065 		if (c == '-')
1066 		  for (i = 0; i < expressionP->X_add_number; ++i)
1067 		    {
1068 		      generic_bignum[i] += 1;
1069 		      if (generic_bignum[i])
1070 			break;
1071 		    }
1072 	      }
1073 	    else if (c == '!')
1074 	      {
1075 		for (i = 0; i < expressionP->X_add_number; ++i)
1076 		  if (generic_bignum[i] != 0)
1077 		    break;
1078 		expressionP->X_add_number = i >= expressionP->X_add_number;
1079 		expressionP->X_op = O_constant;
1080 		expressionP->X_unsigned = 1;
1081 	      }
1082 	  }
1083 	else if (expressionP->X_op != O_illegal
1084 		 && expressionP->X_op != O_absent)
1085 	  {
1086 	    if (c != '+')
1087 	      {
1088 		expressionP->X_add_symbol = make_expr_symbol (expressionP);
1089 		if (c == '-')
1090 		  expressionP->X_op = O_uminus;
1091 		else if (c == '~' || c == '"')
1092 		  expressionP->X_op = O_bit_not;
1093 		else
1094 		  expressionP->X_op = O_logical_not;
1095 		expressionP->X_add_number = 0;
1096 	      }
1097 	  }
1098 	else
1099 	  as_warn (_("Unary operator %c ignored because bad operand follows"),
1100 		   c);
1101       }
1102       break;
1103 
1104 #if defined (DOLLAR_DOT) || defined (TC_M68K)
1105     case '$':
1106       /* '$' is the program counter when in MRI mode, or when
1107 	 DOLLAR_DOT is defined.  */
1108 #ifndef DOLLAR_DOT
1109       if (! flag_m68k_mri)
1110 	goto de_fault;
1111 #endif
1112       if (DOLLAR_AMBIGU && hex_p (*input_line_pointer))
1113 	{
1114 	  /* In MRI mode and on Z80, '$' is also used as the prefix
1115 	     for a hexadecimal constant.  */
1116 	  integer_constant (16, expressionP);
1117 	  break;
1118 	}
1119 
1120       if (is_part_of_name (*input_line_pointer))
1121 	goto isname;
1122 
1123       current_location (expressionP);
1124       break;
1125 #endif
1126 
1127     case '.':
1128       if (!is_part_of_name (*input_line_pointer))
1129 	{
1130 	  current_location (expressionP);
1131 	  break;
1132 	}
1133       else if ((strncasecmp (input_line_pointer, "startof.", 8) == 0
1134 		&& ! is_part_of_name (input_line_pointer[8]))
1135 	       || (strncasecmp (input_line_pointer, "sizeof.", 7) == 0
1136 		   && ! is_part_of_name (input_line_pointer[7])))
1137 	{
1138 	  int start;
1139 
1140 	  start = (input_line_pointer[1] == 't'
1141 		   || input_line_pointer[1] == 'T');
1142 	  input_line_pointer += start ? 8 : 7;
1143 	  SKIP_WHITESPACE ();
1144 	  if (*input_line_pointer != '(')
1145 	    as_bad (_("syntax error in .startof. or .sizeof."));
1146 	  else
1147 	    {
1148 	      char *buf;
1149 
1150 	      ++input_line_pointer;
1151 	      SKIP_WHITESPACE ();
1152 	      name = input_line_pointer;
1153 	      c = get_symbol_end ();
1154 
1155 	      buf = (char *) xmalloc (strlen (name) + 10);
1156 	      if (start)
1157 		sprintf (buf, ".startof.%s", name);
1158 	      else
1159 		sprintf (buf, ".sizeof.%s", name);
1160 	      symbolP = symbol_make (buf);
1161 	      free (buf);
1162 
1163 	      expressionP->X_op = O_symbol;
1164 	      expressionP->X_add_symbol = symbolP;
1165 	      expressionP->X_add_number = 0;
1166 
1167 	      *input_line_pointer = c;
1168 	      SKIP_WHITESPACE ();
1169 	      if (*input_line_pointer != ')')
1170 		as_bad (_("syntax error in .startof. or .sizeof."));
1171 	      else
1172 		++input_line_pointer;
1173 	    }
1174 	  break;
1175 	}
1176       else
1177 	{
1178 	  goto isname;
1179 	}
1180 
1181     case ',':
1182     eol:
1183       /* Can't imagine any other kind of operand.  */
1184       expressionP->X_op = O_absent;
1185       input_line_pointer--;
1186       break;
1187 
1188 #ifdef TC_M68K
1189     case '%':
1190       if (! flag_m68k_mri)
1191 	goto de_fault;
1192       integer_constant (2, expressionP);
1193       break;
1194 
1195     case '@':
1196       if (! flag_m68k_mri)
1197 	goto de_fault;
1198       integer_constant (8, expressionP);
1199       break;
1200 
1201     case ':':
1202       if (! flag_m68k_mri)
1203 	goto de_fault;
1204 
1205       /* In MRI mode, this is a floating point constant represented
1206 	 using hexadecimal digits.  */
1207 
1208       ++input_line_pointer;
1209       integer_constant (16, expressionP);
1210       break;
1211 
1212     case '*':
1213       if (! flag_m68k_mri || is_part_of_name (*input_line_pointer))
1214 	goto de_fault;
1215 
1216       current_location (expressionP);
1217       break;
1218 #endif
1219 
1220     default:
1221 #if defined(md_need_index_operator) || defined(TC_M68K)
1222     de_fault:
1223 #endif
1224       if (is_name_beginner (c))	/* Here if did not begin with a digit.  */
1225 	{
1226 	  /* Identifier begins here.
1227 	     This is kludged for speed, so code is repeated.  */
1228 	isname:
1229 	  name = --input_line_pointer;
1230 	  c = get_symbol_end ();
1231 
1232 #ifdef md_operator
1233 	  {
1234 	    operatorT op = md_operator (name, 1, &c);
1235 
1236 	    switch (op)
1237 	      {
1238 	      case O_uminus:
1239 		*input_line_pointer = c;
1240 		c = '-';
1241 		goto unary;
1242 	      case O_bit_not:
1243 		*input_line_pointer = c;
1244 		c = '~';
1245 		goto unary;
1246 	      case O_logical_not:
1247 		*input_line_pointer = c;
1248 		c = '!';
1249 		goto unary;
1250 	      case O_illegal:
1251 		as_bad (_("invalid use of operator \"%s\""), name);
1252 		break;
1253 	      default:
1254 		break;
1255 	      }
1256 	    if (op != O_absent && op != O_illegal)
1257 	      {
1258 		*input_line_pointer = c;
1259 		expr (9, expressionP, mode);
1260 		expressionP->X_add_symbol = make_expr_symbol (expressionP);
1261 		expressionP->X_op_symbol = NULL;
1262 		expressionP->X_add_number = 0;
1263 		expressionP->X_op = op;
1264 		break;
1265 	      }
1266 	  }
1267 #endif
1268 
1269 #ifdef md_parse_name
1270 	  /* This is a hook for the backend to parse certain names
1271 	     specially in certain contexts.  If a name always has a
1272 	     specific value, it can often be handled by simply
1273 	     entering it in the symbol table.  */
1274 	  if (md_parse_name (name, expressionP, mode, &c))
1275 	    {
1276 	      *input_line_pointer = c;
1277 	      break;
1278 	    }
1279 #endif
1280 
1281 #ifdef TC_I960
1282 	  /* The MRI i960 assembler permits
1283 	         lda sizeof code,g13
1284 	     FIXME: This should use md_parse_name.  */
1285 	  if (flag_mri
1286 	      && (strcasecmp (name, "sizeof") == 0
1287 		  || strcasecmp (name, "startof") == 0))
1288 	    {
1289 	      int start;
1290 	      char *buf;
1291 
1292 	      start = (name[1] == 't'
1293 		       || name[1] == 'T');
1294 
1295 	      *input_line_pointer = c;
1296 	      SKIP_WHITESPACE ();
1297 
1298 	      name = input_line_pointer;
1299 	      c = get_symbol_end ();
1300 
1301 	      buf = (char *) xmalloc (strlen (name) + 10);
1302 	      if (start)
1303 		sprintf (buf, ".startof.%s", name);
1304 	      else
1305 		sprintf (buf, ".sizeof.%s", name);
1306 	      symbolP = symbol_make (buf);
1307 	      free (buf);
1308 
1309 	      expressionP->X_op = O_symbol;
1310 	      expressionP->X_add_symbol = symbolP;
1311 	      expressionP->X_add_number = 0;
1312 
1313 	      *input_line_pointer = c;
1314 	      SKIP_WHITESPACE ();
1315 
1316 	      break;
1317 	    }
1318 #endif
1319 
1320 	  symbolP = symbol_find_or_make (name);
1321 
1322 	  /* If we have an absolute symbol or a reg, then we know its
1323 	     value now.  */
1324 	  segment = S_GET_SEGMENT (symbolP);
1325 	  if (mode != expr_defer
1326 	      && segment == absolute_section
1327 	      && !S_FORCE_RELOC (symbolP, 0))
1328 	    {
1329 	      expressionP->X_op = O_constant;
1330 	      expressionP->X_add_number = S_GET_VALUE (symbolP);
1331 	    }
1332 	  else if (mode != expr_defer && segment == reg_section)
1333 	    {
1334 	      expressionP->X_op = O_register;
1335 	      expressionP->X_add_number = S_GET_VALUE (symbolP);
1336 	    }
1337 	  else
1338 	    {
1339 	      expressionP->X_op = O_symbol;
1340 	      expressionP->X_add_symbol = symbolP;
1341 	      expressionP->X_add_number = 0;
1342 	    }
1343 	  *input_line_pointer = c;
1344 	}
1345       else
1346 	{
1347 	  /* Let the target try to parse it.  Success is indicated by changing
1348 	     the X_op field to something other than O_absent and pointing
1349 	     input_line_pointer past the expression.  If it can't parse the
1350 	     expression, X_op and input_line_pointer should be unchanged.  */
1351 	  expressionP->X_op = O_absent;
1352 	  --input_line_pointer;
1353 	  md_operand (expressionP);
1354 	  if (expressionP->X_op == O_absent)
1355 	    {
1356 	      ++input_line_pointer;
1357 	      as_bad (_("bad expression"));
1358 	      expressionP->X_op = O_constant;
1359 	      expressionP->X_add_number = 0;
1360 	    }
1361 	}
1362       break;
1363     }
1364 
1365   /* It is more 'efficient' to clean up the expressionS when they are
1366      created.  Doing it here saves lines of code.  */
1367   clean_up_expression (expressionP);
1368   SKIP_WHITESPACE ();		/* -> 1st char after operand.  */
1369   know (*input_line_pointer != ' ');
1370 
1371   /* The PA port needs this information.  */
1372   if (expressionP->X_add_symbol)
1373     symbol_mark_used (expressionP->X_add_symbol);
1374 
1375   if (mode != expr_defer)
1376     {
1377       expressionP->X_add_symbol
1378 	= symbol_clone_if_forward_ref (expressionP->X_add_symbol);
1379       expressionP->X_op_symbol
1380 	= symbol_clone_if_forward_ref (expressionP->X_op_symbol);
1381     }
1382 
1383   switch (expressionP->X_op)
1384     {
1385     default:
1386       return absolute_section;
1387     case O_symbol:
1388       return S_GET_SEGMENT (expressionP->X_add_symbol);
1389     case O_register:
1390       return reg_section;
1391     }
1392 }
1393 
1394 /* Internal.  Simplify a struct expression for use by expr ().  */
1395 
1396 /* In:	address of an expressionS.
1397 	The X_op field of the expressionS may only take certain values.
1398 	Elsewise we waste time special-case testing. Sigh. Ditto SEG_ABSENT.
1399 
1400    Out:	expressionS may have been modified:
1401 	Unused fields zeroed to help expr ().  */
1402 
1403 static void
1404 clean_up_expression (expressionS *expressionP)
1405 {
1406   switch (expressionP->X_op)
1407     {
1408     case O_illegal:
1409     case O_absent:
1410       expressionP->X_add_number = 0;
1411       /* Fall through.  */
1412     case O_big:
1413     case O_constant:
1414     case O_register:
1415       expressionP->X_add_symbol = NULL;
1416       /* Fall through.  */
1417     case O_symbol:
1418     case O_uminus:
1419     case O_bit_not:
1420       expressionP->X_op_symbol = NULL;
1421       break;
1422     default:
1423       break;
1424     }
1425 }
1426 
1427 /* Expression parser.  */
1428 
1429 /* We allow an empty expression, and just assume (absolute,0) silently.
1430    Unary operators and parenthetical expressions are treated as operands.
1431    As usual, Q==quantity==operand, O==operator, X==expression mnemonics.
1432 
1433    We used to do an aho/ullman shift-reduce parser, but the logic got so
1434    warped that I flushed it and wrote a recursive-descent parser instead.
1435    Now things are stable, would anybody like to write a fast parser?
1436    Most expressions are either register (which does not even reach here)
1437    or 1 symbol. Then "symbol+constant" and "symbol-symbol" are common.
1438    So I guess it doesn't really matter how inefficient more complex expressions
1439    are parsed.
1440 
1441    After expr(RANK,resultP) input_line_pointer->operator of rank <= RANK.
1442    Also, we have consumed any leading or trailing spaces (operand does that)
1443    and done all intervening operators.
1444 
1445    This returns the segment of the result, which will be
1446    absolute_section or the segment of a symbol.  */
1447 
1448 #undef __
1449 #define __ O_illegal
1450 #ifndef O_SINGLE_EQ
1451 #define O_SINGLE_EQ O_illegal
1452 #endif
1453 
1454 /* Maps ASCII -> operators.  */
1455 static const operatorT op_encoding[256] = {
1456   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1457   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1458 
1459   __, O_bit_or_not, __, __, __, O_modulus, O_bit_and, __,
1460   __, __, O_multiply, O_add, __, O_subtract, __, O_divide,
1461   __, __, __, __, __, __, __, __,
1462   __, __, __, __, O_lt, O_SINGLE_EQ, O_gt, __,
1463   __, __, __, __, __, __, __, __,
1464   __, __, __, __, __, __, __, __,
1465   __, __, __, __, __, __, __, __,
1466   __, __, __,
1467 #ifdef NEED_INDEX_OPERATOR
1468   O_index,
1469 #else
1470   __,
1471 #endif
1472   __, __, O_bit_exclusive_or, __,
1473   __, __, __, __, __, __, __, __,
1474   __, __, __, __, __, __, __, __,
1475   __, __, __, __, __, __, __, __,
1476   __, __, __, __, O_bit_inclusive_or, __, __, __,
1477 
1478   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1479   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1480   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1481   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1482   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1483   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1484   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __,
1485   __, __, __, __, __, __, __, __, __, __, __, __, __, __, __, __
1486 };
1487 
1488 /* Rank	Examples
1489    0	operand, (expression)
1490    1	||
1491    2	&&
1492    3	== <> < <= >= >
1493    4	+ -
1494    5	used for * / % in MRI mode
1495    6	& ^ ! |
1496    7	* / % << >>
1497    8	unary - unary ~
1498 */
1499 static operator_rankT op_rank[O_max] = {
1500   0,	/* O_illegal */
1501   0,	/* O_absent */
1502   0,	/* O_constant */
1503   0,	/* O_symbol */
1504   0,	/* O_symbol_rva */
1505   0,	/* O_register */
1506   0,	/* O_big */
1507   9,	/* O_uminus */
1508   9,	/* O_bit_not */
1509   9,	/* O_logical_not */
1510   8,	/* O_multiply */
1511   8,	/* O_divide */
1512   8,	/* O_modulus */
1513   8,	/* O_left_shift */
1514   8,	/* O_right_shift */
1515   7,	/* O_bit_inclusive_or */
1516   7,	/* O_bit_or_not */
1517   7,	/* O_bit_exclusive_or */
1518   7,	/* O_bit_and */
1519   5,	/* O_add */
1520   5,	/* O_subtract */
1521   4,	/* O_eq */
1522   4,	/* O_ne */
1523   4,	/* O_lt */
1524   4,	/* O_le */
1525   4,	/* O_ge */
1526   4,	/* O_gt */
1527   3,	/* O_logical_and */
1528   2,	/* O_logical_or */
1529   1,	/* O_index */
1530 };
1531 
1532 /* Unfortunately, in MRI mode for the m68k, multiplication and
1533    division have lower precedence than the bit wise operators.  This
1534    function sets the operator precedences correctly for the current
1535    mode.  Also, MRI uses a different bit_not operator, and this fixes
1536    that as well.  */
1537 
1538 #define STANDARD_MUL_PRECEDENCE 8
1539 #define MRI_MUL_PRECEDENCE 6
1540 
1541 void
1542 expr_set_precedence (void)
1543 {
1544   if (flag_m68k_mri)
1545     {
1546       op_rank[O_multiply] = MRI_MUL_PRECEDENCE;
1547       op_rank[O_divide] = MRI_MUL_PRECEDENCE;
1548       op_rank[O_modulus] = MRI_MUL_PRECEDENCE;
1549     }
1550   else
1551     {
1552       op_rank[O_multiply] = STANDARD_MUL_PRECEDENCE;
1553       op_rank[O_divide] = STANDARD_MUL_PRECEDENCE;
1554       op_rank[O_modulus] = STANDARD_MUL_PRECEDENCE;
1555     }
1556 }
1557 
1558 void
1559 expr_set_rank (operatorT op, operator_rankT rank)
1560 {
1561   gas_assert (op >= O_md1 && op < ARRAY_SIZE (op_rank));
1562   op_rank[op] = rank;
1563 }
1564 
1565 /* Initialize the expression parser.  */
1566 
1567 void
1568 expr_begin (void)
1569 {
1570   expr_set_precedence ();
1571 
1572   /* Verify that X_op field is wide enough.  */
1573   {
1574     expressionS e;
1575     e.X_op = O_max;
1576     gas_assert (e.X_op == O_max);
1577   }
1578 }
1579 
1580 /* Return the encoding for the operator at INPUT_LINE_POINTER, and
1581    sets NUM_CHARS to the number of characters in the operator.
1582    Does not advance INPUT_LINE_POINTER.  */
1583 
1584 static inline operatorT
1585 operatorf (int *num_chars)
1586 {
1587   int c;
1588   operatorT ret;
1589 
1590   c = *input_line_pointer & 0xff;
1591   *num_chars = 1;
1592 
1593   if (is_end_of_line[c])
1594     return O_illegal;
1595 
1596 #ifdef md_operator
1597   if (is_name_beginner (c))
1598     {
1599       char *name = input_line_pointer;
1600       char ec = get_symbol_end ();
1601 
1602       ret = md_operator (name, 2, &ec);
1603       switch (ret)
1604 	{
1605 	case O_absent:
1606 	  *input_line_pointer = ec;
1607 	  input_line_pointer = name;
1608 	  break;
1609 	case O_uminus:
1610 	case O_bit_not:
1611 	case O_logical_not:
1612 	  as_bad (_("invalid use of operator \"%s\""), name);
1613 	  ret = O_illegal;
1614 	  /* FALLTHROUGH */
1615 	default:
1616 	  *input_line_pointer = ec;
1617 	  *num_chars = input_line_pointer - name;
1618 	  input_line_pointer = name;
1619 	  return ret;
1620 	}
1621     }
1622 #endif
1623 
1624   switch (c)
1625     {
1626     default:
1627       ret = op_encoding[c];
1628 #ifdef md_operator
1629       if (ret == O_illegal)
1630 	{
1631 	  char *start = input_line_pointer;
1632 
1633 	  ret = md_operator (NULL, 2, NULL);
1634 	  if (ret != O_illegal)
1635 	    *num_chars = input_line_pointer - start;
1636 	  input_line_pointer = start;
1637 	}
1638 #endif
1639       return ret;
1640 
1641     case '+':
1642     case '-':
1643       return op_encoding[c];
1644 
1645     case '<':
1646       switch (input_line_pointer[1])
1647 	{
1648 	default:
1649 	  return op_encoding[c];
1650 	case '<':
1651 	  ret = O_left_shift;
1652 	  break;
1653 	case '>':
1654 	  ret = O_ne;
1655 	  break;
1656 	case '=':
1657 	  ret = O_le;
1658 	  break;
1659 	}
1660       *num_chars = 2;
1661       return ret;
1662 
1663     case '=':
1664       if (input_line_pointer[1] != '=')
1665 	return op_encoding[c];
1666 
1667       *num_chars = 2;
1668       return O_eq;
1669 
1670     case '>':
1671       switch (input_line_pointer[1])
1672 	{
1673 	default:
1674 	  return op_encoding[c];
1675 	case '>':
1676 	  ret = O_right_shift;
1677 	  break;
1678 	case '=':
1679 	  ret = O_ge;
1680 	  break;
1681 	}
1682       *num_chars = 2;
1683       return ret;
1684 
1685     case '!':
1686       switch (input_line_pointer[1])
1687 	{
1688 	case '!':
1689 	  /* We accept !! as equivalent to ^ for MRI compatibility. */
1690 	  *num_chars = 2;
1691 	  return O_bit_exclusive_or;
1692 	case '=':
1693 	  /* We accept != as equivalent to <>.  */
1694 	  *num_chars = 2;
1695 	  return O_ne;
1696 	default:
1697 	  if (flag_m68k_mri)
1698 	    return O_bit_inclusive_or;
1699 	  return op_encoding[c];
1700 	}
1701 
1702     case '|':
1703       if (input_line_pointer[1] != '|')
1704 	return op_encoding[c];
1705 
1706       *num_chars = 2;
1707       return O_logical_or;
1708 
1709     case '&':
1710       if (input_line_pointer[1] != '&')
1711 	return op_encoding[c];
1712 
1713       *num_chars = 2;
1714       return O_logical_and;
1715     }
1716 
1717   /* NOTREACHED  */
1718 }
1719 
1720 /* Parse an expression.  */
1721 
1722 segT
1723 expr (int rankarg,		/* Larger # is higher rank.  */
1724       expressionS *resultP,	/* Deliver result here.  */
1725       enum expr_mode mode	/* Controls behavior.  */)
1726 {
1727   operator_rankT rank = (operator_rankT) rankarg;
1728   segT retval;
1729   expressionS right;
1730   operatorT op_left;
1731   operatorT op_right;
1732   int op_chars;
1733 
1734   know (rankarg >= 0);
1735 
1736   /* Save the value of dot for the fixup code.  */
1737   if (rank == 0)
1738     dot_value = frag_now_fix ();
1739 
1740   retval = operand (resultP, mode);
1741 
1742   /* operand () gobbles spaces.  */
1743   know (*input_line_pointer != ' ');
1744 
1745   op_left = operatorf (&op_chars);
1746   while (op_left != O_illegal && op_rank[(int) op_left] > rank)
1747     {
1748       segT rightseg;
1749       offsetT frag_off;
1750 
1751       input_line_pointer += op_chars;	/* -> after operator.  */
1752 
1753       right.X_md = 0;
1754       rightseg = expr (op_rank[(int) op_left], &right, mode);
1755       if (right.X_op == O_absent)
1756 	{
1757 	  as_warn (_("missing operand; zero assumed"));
1758 	  right.X_op = O_constant;
1759 	  right.X_add_number = 0;
1760 	  right.X_add_symbol = NULL;
1761 	  right.X_op_symbol = NULL;
1762 	}
1763 
1764       know (*input_line_pointer != ' ');
1765 
1766       if (op_left == O_index)
1767 	{
1768 	  if (*input_line_pointer != ']')
1769 	    as_bad ("missing right bracket");
1770 	  else
1771 	    {
1772 	      ++input_line_pointer;
1773 	      SKIP_WHITESPACE ();
1774 	    }
1775 	}
1776 
1777       op_right = operatorf (&op_chars);
1778 
1779       know (op_right == O_illegal || op_left == O_index
1780 	    || op_rank[(int) op_right] <= op_rank[(int) op_left]);
1781       know ((int) op_left >= (int) O_multiply);
1782 #ifndef md_operator
1783       know ((int) op_left <= (int) O_index);
1784 #else
1785       know ((int) op_left < (int) O_max);
1786 #endif
1787 
1788       /* input_line_pointer->after right-hand quantity.  */
1789       /* left-hand quantity in resultP.  */
1790       /* right-hand quantity in right.  */
1791       /* operator in op_left.  */
1792 
1793       if (resultP->X_op == O_big)
1794 	{
1795 	  if (resultP->X_add_number > 0)
1796 	    as_warn (_("left operand is a bignum; integer 0 assumed"));
1797 	  else
1798 	    as_warn (_("left operand is a float; integer 0 assumed"));
1799 	  resultP->X_op = O_constant;
1800 	  resultP->X_add_number = 0;
1801 	  resultP->X_add_symbol = NULL;
1802 	  resultP->X_op_symbol = NULL;
1803 	}
1804       if (right.X_op == O_big)
1805 	{
1806 	  if (right.X_add_number > 0)
1807 	    as_warn (_("right operand is a bignum; integer 0 assumed"));
1808 	  else
1809 	    as_warn (_("right operand is a float; integer 0 assumed"));
1810 	  right.X_op = O_constant;
1811 	  right.X_add_number = 0;
1812 	  right.X_add_symbol = NULL;
1813 	  right.X_op_symbol = NULL;
1814 	}
1815 
1816       /* Optimize common cases.  */
1817 #ifdef md_optimize_expr
1818       if (md_optimize_expr (resultP, op_left, &right))
1819 	{
1820 	  /* Skip.  */
1821 	  ;
1822 	}
1823       else
1824 #endif
1825 #ifndef md_register_arithmetic
1826 # define md_register_arithmetic 1
1827 #endif
1828       if (op_left == O_add && right.X_op == O_constant
1829 	  && (md_register_arithmetic || resultP->X_op != O_register))
1830 	{
1831 	  /* X + constant.  */
1832 	  resultP->X_add_number += right.X_add_number;
1833 	}
1834       /* This case comes up in PIC code.  */
1835       else if (op_left == O_subtract
1836 	       && right.X_op == O_symbol
1837 	       && resultP->X_op == O_symbol
1838 	       && retval == rightseg
1839 #ifdef md_allow_local_subtract
1840 	       && md_allow_local_subtract (resultP, & right, rightseg)
1841 #endif
1842 	       && ((SEG_NORMAL (rightseg)
1843 		    && !S_FORCE_RELOC (resultP->X_add_symbol, 0)
1844 		    && !S_FORCE_RELOC (right.X_add_symbol, 0))
1845 		   || right.X_add_symbol == resultP->X_add_symbol)
1846 	       && frag_offset_fixed_p (symbol_get_frag (resultP->X_add_symbol),
1847 				       symbol_get_frag (right.X_add_symbol),
1848 				       &frag_off))
1849 	{
1850 	  resultP->X_add_number -= right.X_add_number;
1851 	  resultP->X_add_number -= frag_off / OCTETS_PER_BYTE;
1852 	  resultP->X_add_number += (S_GET_VALUE (resultP->X_add_symbol)
1853 				    - S_GET_VALUE (right.X_add_symbol));
1854 	  resultP->X_op = O_constant;
1855 	  resultP->X_add_symbol = 0;
1856 	}
1857       else if (op_left == O_subtract && right.X_op == O_constant
1858 	       && (md_register_arithmetic || resultP->X_op != O_register))
1859 	{
1860 	  /* X - constant.  */
1861 	  resultP->X_add_number -= right.X_add_number;
1862 	}
1863       else if (op_left == O_add && resultP->X_op == O_constant
1864 	       && (md_register_arithmetic || right.X_op != O_register))
1865 	{
1866 	  /* Constant + X.  */
1867 	  resultP->X_op = right.X_op;
1868 	  resultP->X_add_symbol = right.X_add_symbol;
1869 	  resultP->X_op_symbol = right.X_op_symbol;
1870 	  resultP->X_add_number += right.X_add_number;
1871 	  retval = rightseg;
1872 	}
1873       else if (resultP->X_op == O_constant && right.X_op == O_constant)
1874 	{
1875 	  /* Constant OP constant.  */
1876 	  offsetT v = right.X_add_number;
1877 	  if (v == 0 && (op_left == O_divide || op_left == O_modulus))
1878 	    {
1879 	      as_warn (_("division by zero"));
1880 	      v = 1;
1881 	    }
1882 	  if ((valueT) v >= sizeof(valueT) * CHAR_BIT
1883 	      && (op_left == O_left_shift || op_left == O_right_shift))
1884 	    {
1885 	      as_warn_value_out_of_range (_("shift count"), v, 0,
1886 					  sizeof(valueT) * CHAR_BIT - 1,
1887 					  NULL, 0);
1888 	      resultP->X_add_number = v = 0;
1889 	    }
1890 	  switch (op_left)
1891 	    {
1892 	    default:			goto general;
1893 	    case O_multiply:		resultP->X_add_number *= v; break;
1894 	    case O_divide:		resultP->X_add_number /= v; break;
1895 	    case O_modulus:		resultP->X_add_number %= v; break;
1896 	    case O_left_shift:		resultP->X_add_number <<= v; break;
1897 	    case O_right_shift:
1898 	      /* We always use unsigned shifts, to avoid relying on
1899 		 characteristics of the compiler used to compile gas.  */
1900 	      resultP->X_add_number =
1901 		(offsetT) ((valueT) resultP->X_add_number >> (valueT) v);
1902 	      break;
1903 	    case O_bit_inclusive_or:	resultP->X_add_number |= v; break;
1904 	    case O_bit_or_not:		resultP->X_add_number |= ~v; break;
1905 	    case O_bit_exclusive_or:	resultP->X_add_number ^= v; break;
1906 	    case O_bit_and:		resultP->X_add_number &= v; break;
1907 	      /* Constant + constant (O_add) is handled by the
1908 		 previous if statement for constant + X, so is omitted
1909 		 here.  */
1910 	    case O_subtract:		resultP->X_add_number -= v; break;
1911 	    case O_eq:
1912 	      resultP->X_add_number =
1913 		resultP->X_add_number == v ? ~ (offsetT) 0 : 0;
1914 	      break;
1915 	    case O_ne:
1916 	      resultP->X_add_number =
1917 		resultP->X_add_number != v ? ~ (offsetT) 0 : 0;
1918 	      break;
1919 	    case O_lt:
1920 	      resultP->X_add_number =
1921 		resultP->X_add_number <  v ? ~ (offsetT) 0 : 0;
1922 	      break;
1923 	    case O_le:
1924 	      resultP->X_add_number =
1925 		resultP->X_add_number <= v ? ~ (offsetT) 0 : 0;
1926 	      break;
1927 	    case O_ge:
1928 	      resultP->X_add_number =
1929 		resultP->X_add_number >= v ? ~ (offsetT) 0 : 0;
1930 	      break;
1931 	    case O_gt:
1932 	      resultP->X_add_number =
1933 		resultP->X_add_number >  v ? ~ (offsetT) 0 : 0;
1934 	      break;
1935 	    case O_logical_and:
1936 	      resultP->X_add_number = resultP->X_add_number && v;
1937 	      break;
1938 	    case O_logical_or:
1939 	      resultP->X_add_number = resultP->X_add_number || v;
1940 	      break;
1941 	    }
1942 	}
1943       else if (resultP->X_op == O_symbol
1944 	       && right.X_op == O_symbol
1945 	       && (op_left == O_add
1946 		   || op_left == O_subtract
1947 		   || (resultP->X_add_number == 0
1948 		       && right.X_add_number == 0)))
1949 	{
1950 	  /* Symbol OP symbol.  */
1951 	  resultP->X_op = op_left;
1952 	  resultP->X_op_symbol = right.X_add_symbol;
1953 	  if (op_left == O_add)
1954 	    resultP->X_add_number += right.X_add_number;
1955 	  else if (op_left == O_subtract)
1956 	    {
1957 	      resultP->X_add_number -= right.X_add_number;
1958 	      if (retval == rightseg
1959 		  && SEG_NORMAL (retval)
1960 		  && !S_FORCE_RELOC (resultP->X_add_symbol, 0)
1961 		  && !S_FORCE_RELOC (right.X_add_symbol, 0))
1962 		{
1963 		  retval = absolute_section;
1964 		  rightseg = absolute_section;
1965 		}
1966 	    }
1967 	}
1968       else
1969 	{
1970         general:
1971 	  /* The general case.  */
1972 	  resultP->X_add_symbol = make_expr_symbol (resultP);
1973 	  resultP->X_op_symbol = make_expr_symbol (&right);
1974 	  resultP->X_op = op_left;
1975 	  resultP->X_add_number = 0;
1976 	  resultP->X_unsigned = 1;
1977 	}
1978 
1979       if (retval != rightseg)
1980 	{
1981 	  if (retval == undefined_section)
1982 	    ;
1983 	  else if (rightseg == undefined_section)
1984 	    retval = rightseg;
1985 	  else if (retval == expr_section)
1986 	    ;
1987 	  else if (rightseg == expr_section)
1988 	    retval = rightseg;
1989 	  else if (retval == reg_section)
1990 	    ;
1991 	  else if (rightseg == reg_section)
1992 	    retval = rightseg;
1993 	  else if (rightseg == absolute_section)
1994 	    ;
1995 	  else if (retval == absolute_section)
1996 	    retval = rightseg;
1997 #ifdef DIFF_EXPR_OK
1998 	  else if (op_left == O_subtract)
1999 	    ;
2000 #endif
2001 	  else
2002 	    as_bad (_("operation combines symbols in different segments"));
2003 	}
2004 
2005       op_left = op_right;
2006     }				/* While next operator is >= this rank.  */
2007 
2008   /* The PA port needs this information.  */
2009   if (resultP->X_add_symbol)
2010     symbol_mark_used (resultP->X_add_symbol);
2011 
2012   if (rank == 0 && mode == expr_evaluate)
2013     resolve_expression (resultP);
2014 
2015   return resultP->X_op == O_constant ? absolute_section : retval;
2016 }
2017 
2018 /* Resolve an expression without changing any symbols/sub-expressions
2019    used.  */
2020 
2021 int
2022 resolve_expression (expressionS *expressionP)
2023 {
2024   /* Help out with CSE.  */
2025   valueT final_val = expressionP->X_add_number;
2026   symbolS *add_symbol = expressionP->X_add_symbol;
2027   symbolS *orig_add_symbol = add_symbol;
2028   symbolS *op_symbol = expressionP->X_op_symbol;
2029   operatorT op = expressionP->X_op;
2030   valueT left, right;
2031   segT seg_left, seg_right;
2032   fragS *frag_left, *frag_right;
2033   offsetT frag_off;
2034 
2035   switch (op)
2036     {
2037     default:
2038       return 0;
2039 
2040     case O_constant:
2041     case O_register:
2042       left = 0;
2043       break;
2044 
2045     case O_symbol:
2046     case O_symbol_rva:
2047       if (!snapshot_symbol (&add_symbol, &left, &seg_left, &frag_left))
2048 	return 0;
2049 
2050       break;
2051 
2052     case O_uminus:
2053     case O_bit_not:
2054     case O_logical_not:
2055       if (!snapshot_symbol (&add_symbol, &left, &seg_left, &frag_left))
2056 	return 0;
2057 
2058       if (seg_left != absolute_section)
2059 	return 0;
2060 
2061       if (op == O_logical_not)
2062 	left = !left;
2063       else if (op == O_uminus)
2064 	left = -left;
2065       else
2066 	left = ~left;
2067       op = O_constant;
2068       break;
2069 
2070     case O_multiply:
2071     case O_divide:
2072     case O_modulus:
2073     case O_left_shift:
2074     case O_right_shift:
2075     case O_bit_inclusive_or:
2076     case O_bit_or_not:
2077     case O_bit_exclusive_or:
2078     case O_bit_and:
2079     case O_add:
2080     case O_subtract:
2081     case O_eq:
2082     case O_ne:
2083     case O_lt:
2084     case O_le:
2085     case O_ge:
2086     case O_gt:
2087     case O_logical_and:
2088     case O_logical_or:
2089       if (!snapshot_symbol (&add_symbol, &left, &seg_left, &frag_left)
2090 	  || !snapshot_symbol (&op_symbol, &right, &seg_right, &frag_right))
2091 	return 0;
2092 
2093       /* Simplify addition or subtraction of a constant by folding the
2094 	 constant into X_add_number.  */
2095       if (op == O_add)
2096 	{
2097 	  if (seg_right == absolute_section)
2098 	    {
2099 	      final_val += right;
2100 	      op = O_symbol;
2101 	      break;
2102 	    }
2103 	  else if (seg_left == absolute_section)
2104 	    {
2105 	      final_val += left;
2106 	      left = right;
2107 	      seg_left = seg_right;
2108 	      add_symbol = op_symbol;
2109 	      orig_add_symbol = expressionP->X_op_symbol;
2110 	      op = O_symbol;
2111 	      break;
2112 	    }
2113 	}
2114       else if (op == O_subtract)
2115 	{
2116 	  if (seg_right == absolute_section)
2117 	    {
2118 	      final_val -= right;
2119 	      op = O_symbol;
2120 	      break;
2121 	    }
2122 	}
2123 
2124       /* Equality and non-equality tests are permitted on anything.
2125 	 Subtraction, and other comparison operators are permitted if
2126 	 both operands are in the same section.
2127 	 Shifts by constant zero are permitted on anything.
2128 	 Multiplies, bit-ors, and bit-ands with constant zero are
2129 	 permitted on anything.
2130 	 Multiplies and divides by constant one are permitted on
2131 	 anything.
2132 	 Binary operations with both operands being the same register
2133 	 or undefined symbol are permitted if the result doesn't depend
2134 	 on the input value.
2135 	 Otherwise, both operands must be absolute.  We already handled
2136 	 the case of addition or subtraction of a constant above.  */
2137       frag_off = 0;
2138       if (!(seg_left == absolute_section
2139 	       && seg_right == absolute_section)
2140 	  && !(op == O_eq || op == O_ne)
2141 	  && !((op == O_subtract
2142 		|| op == O_lt || op == O_le || op == O_ge || op == O_gt)
2143 	       && seg_left == seg_right
2144 	       && (finalize_syms
2145 		   || frag_offset_fixed_p (frag_left, frag_right, &frag_off))
2146 	       && (seg_left != reg_section || left == right)
2147 	       && (seg_left != undefined_section || add_symbol == op_symbol)))
2148 	{
2149 	  if ((seg_left == absolute_section && left == 0)
2150 	      || (seg_right == absolute_section && right == 0))
2151 	    {
2152 	      if (op == O_bit_exclusive_or || op == O_bit_inclusive_or)
2153 		{
2154 		  if (!(seg_right == absolute_section && right == 0))
2155 		    {
2156 		      seg_left = seg_right;
2157 		      left = right;
2158 		      add_symbol = op_symbol;
2159 		      orig_add_symbol = expressionP->X_op_symbol;
2160 		    }
2161 		  op = O_symbol;
2162 		  break;
2163 		}
2164 	      else if (op == O_left_shift || op == O_right_shift)
2165 		{
2166 		  if (!(seg_left == absolute_section && left == 0))
2167 		    {
2168 		      op = O_symbol;
2169 		      break;
2170 		    }
2171 		}
2172 	      else if (op != O_multiply
2173 		       && op != O_bit_or_not && op != O_bit_and)
2174 	        return 0;
2175 	    }
2176 	  else if (op == O_multiply
2177 		   && seg_left == absolute_section && left == 1)
2178 	    {
2179 	      seg_left = seg_right;
2180 	      left = right;
2181 	      add_symbol = op_symbol;
2182 	      orig_add_symbol = expressionP->X_op_symbol;
2183 	      op = O_symbol;
2184 	      break;
2185 	    }
2186 	  else if ((op == O_multiply || op == O_divide)
2187 		   && seg_right == absolute_section && right == 1)
2188 	    {
2189 	      op = O_symbol;
2190 	      break;
2191 	    }
2192 	  else if (!(left == right
2193 		     && ((seg_left == reg_section && seg_right == reg_section)
2194 			 || (seg_left == undefined_section
2195 			     && seg_right == undefined_section
2196 			     && add_symbol == op_symbol))))
2197 	    return 0;
2198 	  else if (op == O_bit_and || op == O_bit_inclusive_or)
2199 	    {
2200 	      op = O_symbol;
2201 	      break;
2202 	    }
2203 	  else if (op != O_bit_exclusive_or && op != O_bit_or_not)
2204 	    return 0;
2205 	}
2206 
2207       right += frag_off / OCTETS_PER_BYTE;
2208       switch (op)
2209 	{
2210 	case O_add:			left += right; break;
2211 	case O_subtract:		left -= right; break;
2212 	case O_multiply:		left *= right; break;
2213 	case O_divide:
2214 	  if (right == 0)
2215 	    return 0;
2216 	  left = (offsetT) left / (offsetT) right;
2217 	  break;
2218 	case O_modulus:
2219 	  if (right == 0)
2220 	    return 0;
2221 	  left = (offsetT) left % (offsetT) right;
2222 	  break;
2223 	case O_left_shift:		left <<= right; break;
2224 	case O_right_shift:		left >>= right; break;
2225 	case O_bit_inclusive_or:	left |= right; break;
2226 	case O_bit_or_not:		left |= ~right; break;
2227 	case O_bit_exclusive_or:	left ^= right; break;
2228 	case O_bit_and:			left &= right; break;
2229 	case O_eq:
2230 	case O_ne:
2231 	  left = (left == right
2232 		  && seg_left == seg_right
2233 		  && (finalize_syms || frag_left == frag_right)
2234 		  && (seg_left != undefined_section
2235 		      || add_symbol == op_symbol)
2236 		  ? ~ (valueT) 0 : 0);
2237 	  if (op == O_ne)
2238 	    left = ~left;
2239 	  break;
2240 	case O_lt:
2241 	  left = (offsetT) left <  (offsetT) right ? ~ (valueT) 0 : 0;
2242 	  break;
2243 	case O_le:
2244 	  left = (offsetT) left <= (offsetT) right ? ~ (valueT) 0 : 0;
2245 	  break;
2246 	case O_ge:
2247 	  left = (offsetT) left >= (offsetT) right ? ~ (valueT) 0 : 0;
2248 	  break;
2249 	case O_gt:
2250 	  left = (offsetT) left >  (offsetT) right ? ~ (valueT) 0 : 0;
2251 	  break;
2252 	case O_logical_and:	left = left && right; break;
2253 	case O_logical_or:	left = left || right; break;
2254 	default:		abort ();
2255 	}
2256 
2257       op = O_constant;
2258       break;
2259     }
2260 
2261   if (op == O_symbol)
2262     {
2263       if (seg_left == absolute_section)
2264 	op = O_constant;
2265       else if (seg_left == reg_section && final_val == 0)
2266 	op = O_register;
2267       else if (!symbol_same_p (add_symbol, orig_add_symbol))
2268 	final_val += left;
2269       expressionP->X_add_symbol = add_symbol;
2270     }
2271   expressionP->X_op = op;
2272 
2273   if (op == O_constant || op == O_register)
2274     final_val += left;
2275   expressionP->X_add_number = final_val;
2276 
2277   return 1;
2278 }
2279 
2280 /* This lives here because it belongs equally in expr.c & read.c.
2281    expr.c is just a branch office read.c anyway, and putting it
2282    here lessens the crowd at read.c.
2283 
2284    Assume input_line_pointer is at start of symbol name.
2285    Advance input_line_pointer past symbol name.
2286    Turn that character into a '\0', returning its former value.
2287    This allows a string compare (RMS wants symbol names to be strings)
2288    of the symbol name.
2289    There will always be a char following symbol name, because all good
2290    lines end in end-of-line.  */
2291 
2292 char
2293 get_symbol_end (void)
2294 {
2295   char c;
2296 
2297   /* We accept \001 in a name in case this is being called with a
2298      constructed string.  */
2299   if (is_name_beginner (c = *input_line_pointer++) || c == '\001')
2300     {
2301       while (is_part_of_name (c = *input_line_pointer++)
2302 	     || c == '\001')
2303 	;
2304       if (is_name_ender (c))
2305 	c = *input_line_pointer++;
2306     }
2307   *--input_line_pointer = 0;
2308   return (c);
2309 }
2310 
2311 unsigned int
2312 get_single_number (void)
2313 {
2314   expressionS exp;
2315   operand (&exp, expr_normal);
2316   return exp.X_add_number;
2317 }
2318