1 /* Generic routines for manipulating SSA_NAME expressions
2 Copyright (C) 2003-2020 Free Software Foundation, Inc.
3
4 This file is part of GCC.
5
6 GCC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
9 any later version.
10
11 GCC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
19
20 #include "config.h"
21 #include "system.h"
22 #include "coretypes.h"
23 #include "backend.h"
24 #include "tree.h"
25 #include "gimple.h"
26 #include "tree-pass.h"
27 #include "ssa.h"
28 #include "gimple-iterator.h"
29 #include "stor-layout.h"
30 #include "tree-into-ssa.h"
31 #include "tree-ssa.h"
32 #include "cfgloop.h"
33 #include "tree-scalar-evolution.h"
34
35 /* Rewriting a function into SSA form can create a huge number of SSA_NAMEs,
36 many of which may be thrown away shortly after their creation if jumps
37 were threaded through PHI nodes.
38
39 While our garbage collection mechanisms will handle this situation, it
40 is extremely wasteful to create nodes and throw them away, especially
41 when the nodes can be reused.
42
43 For PR 8361, we can significantly reduce the number of nodes allocated
44 and thus the total amount of memory allocated by managing SSA_NAMEs a
45 little. This additionally helps reduce the amount of work done by the
46 garbage collector. Similar results have been seen on a wider variety
47 of tests (such as the compiler itself).
48
49 Right now we maintain our free list on a per-function basis. It may
50 or may not make sense to maintain the free list for the duration of
51 a compilation unit.
52
53 External code should rely solely upon HIGHEST_SSA_VERSION and the
54 externally defined functions. External code should not know about
55 the details of the free list management.
56
57 External code should also not assume the version number on nodes is
58 monotonically increasing. We reuse the version number when we
59 reuse an SSA_NAME expression. This helps keep arrays and bitmaps
60 more compact. */
61
62
63 /* Version numbers with special meanings. We start allocating new version
64 numbers after the special ones. */
65 #define UNUSED_NAME_VERSION 0
66
67 unsigned int ssa_name_nodes_reused;
68 unsigned int ssa_name_nodes_created;
69
70 #define FREE_SSANAMES(fun) (fun)->gimple_df->free_ssanames
71 #define FREE_SSANAMES_QUEUE(fun) (fun)->gimple_df->free_ssanames_queue
72
73
74 /* Initialize management of SSA_NAMEs to default SIZE. If SIZE is
75 zero use default. */
76
77 void
init_ssanames(struct function * fn,int size)78 init_ssanames (struct function *fn, int size)
79 {
80 if (size < 50)
81 size = 50;
82
83 vec_alloc (SSANAMES (fn), size);
84
85 /* Version 0 is special, so reserve the first slot in the table. Though
86 currently unused, we may use version 0 in alias analysis as part of
87 the heuristics used to group aliases when the alias sets are too
88 large.
89
90 We use vec::quick_push here because we know that SSA_NAMES has at
91 least 50 elements reserved in it. */
92 SSANAMES (fn)->quick_push (NULL_TREE);
93 FREE_SSANAMES (fn) = NULL;
94 FREE_SSANAMES_QUEUE (fn) = NULL;
95
96 fn->gimple_df->ssa_renaming_needed = 0;
97 fn->gimple_df->rename_vops = 0;
98 }
99
100 /* Finalize management of SSA_NAMEs. */
101
102 void
fini_ssanames(struct function * fn)103 fini_ssanames (struct function *fn)
104 {
105 vec_free (SSANAMES (fn));
106 vec_free (FREE_SSANAMES (fn));
107 vec_free (FREE_SSANAMES_QUEUE (fn));
108 }
109
110 /* Dump some simple statistics regarding the re-use of SSA_NAME nodes. */
111
112 void
ssanames_print_statistics(void)113 ssanames_print_statistics (void)
114 {
115 fprintf (stderr, "%-32s" PRsa (11) "\n", "SSA_NAME nodes allocated:",
116 SIZE_AMOUNT (ssa_name_nodes_created));
117 fprintf (stderr, "%-32s" PRsa (11) "\n", "SSA_NAME nodes reused:",
118 SIZE_AMOUNT (ssa_name_nodes_reused));
119 }
120
121 /* Verify the state of the SSA_NAME lists.
122
123 There must be no duplicates on the free list.
124 Every name on the free list must be marked as on the free list.
125 Any name on the free list must not appear in the IL.
126 No names can be leaked. */
127
128 DEBUG_FUNCTION void
verify_ssaname_freelists(struct function * fun)129 verify_ssaname_freelists (struct function *fun)
130 {
131 if (!gimple_in_ssa_p (fun))
132 return;
133
134 auto_bitmap names_in_il;
135
136 /* Walk the entire IL noting every SSA_NAME we see. */
137 basic_block bb;
138 FOR_EACH_BB_FN (bb, fun)
139 {
140 tree t;
141 /* First note the result and arguments of PHI nodes. */
142 for (gphi_iterator gsi = gsi_start_phis (bb);
143 !gsi_end_p (gsi);
144 gsi_next (&gsi))
145 {
146 gphi *phi = gsi.phi ();
147 t = gimple_phi_result (phi);
148 bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
149
150 for (unsigned int i = 0; i < gimple_phi_num_args (phi); i++)
151 {
152 t = gimple_phi_arg_def (phi, i);
153 if (TREE_CODE (t) == SSA_NAME)
154 bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
155 }
156 }
157
158 /* Then note the operands of each statement. */
159 for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
160 !gsi_end_p (gsi);
161 gsi_next (&gsi))
162 {
163 ssa_op_iter iter;
164 gimple *stmt = gsi_stmt (gsi);
165 FOR_EACH_SSA_TREE_OPERAND (t, stmt, iter, SSA_OP_ALL_OPERANDS)
166 bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
167 }
168 }
169
170 /* Now walk the free list noting what we find there and verifying
171 there are no duplicates. */
172 auto_bitmap names_in_freelists;
173 if (FREE_SSANAMES (fun))
174 {
175 for (unsigned int i = 0; i < FREE_SSANAMES (fun)->length (); i++)
176 {
177 tree t = (*FREE_SSANAMES (fun))[i];
178
179 /* Verify that the name is marked as being in the free list. */
180 gcc_assert (SSA_NAME_IN_FREE_LIST (t));
181
182 /* Verify the name has not already appeared in the free list and
183 note it in the list of names found in the free list. */
184 gcc_assert (!bitmap_bit_p (names_in_freelists, SSA_NAME_VERSION (t)));
185 bitmap_set_bit (names_in_freelists, SSA_NAME_VERSION (t));
186 }
187 }
188
189 /* Similarly for the names in the pending free list. */
190 if (FREE_SSANAMES_QUEUE (fun))
191 {
192 for (unsigned int i = 0; i < FREE_SSANAMES_QUEUE (fun)->length (); i++)
193 {
194 tree t = (*FREE_SSANAMES_QUEUE (fun))[i];
195
196 /* Verify that the name is marked as being in the free list. */
197 gcc_assert (SSA_NAME_IN_FREE_LIST (t));
198
199 /* Verify the name has not already appeared in the free list and
200 note it in the list of names found in the free list. */
201 gcc_assert (!bitmap_bit_p (names_in_freelists, SSA_NAME_VERSION (t)));
202 bitmap_set_bit (names_in_freelists, SSA_NAME_VERSION (t));
203 }
204 }
205
206 /* If any name appears in both the IL and the freelists, then
207 something horrible has happened. */
208 bool intersect_p = bitmap_intersect_p (names_in_il, names_in_freelists);
209 gcc_assert (!intersect_p);
210
211 /* Names can be queued up for release if there is an ssa update
212 pending. Pretend we saw them in the IL. */
213 if (names_to_release)
214 bitmap_ior_into (names_in_il, names_to_release);
215
216 /* Function splitting can "lose" SSA_NAMEs in an effort to ensure that
217 debug/non-debug compilations have the same SSA_NAMEs. So for each
218 lost SSA_NAME, see if it's likely one from that wart. These will always
219 be marked as default definitions. So we loosely assume that anything
220 marked as a default definition isn't leaked by pretending they are
221 in the IL. */
222 for (unsigned int i = UNUSED_NAME_VERSION + 1; i < num_ssa_names; i++)
223 if (ssa_name (i) && SSA_NAME_IS_DEFAULT_DEF (ssa_name (i)))
224 bitmap_set_bit (names_in_il, i);
225
226 unsigned int i;
227 bitmap_iterator bi;
228 auto_bitmap all_names;
229 bitmap_set_range (all_names, UNUSED_NAME_VERSION + 1, num_ssa_names - 1);
230 bitmap_ior_into (names_in_il, names_in_freelists);
231
232 /* Any name not mentioned in the IL and not in the feelists
233 has been leaked. */
234 EXECUTE_IF_AND_COMPL_IN_BITMAP(all_names, names_in_il,
235 UNUSED_NAME_VERSION + 1, i, bi)
236 gcc_assert (!ssa_name (i));
237 }
238
239 /* Move all SSA_NAMEs from FREE_SSA_NAMES_QUEUE to FREE_SSA_NAMES.
240
241 We do not, but should have a mode to verify the state of the SSA_NAMEs
242 lists. In particular at this point every name must be in the IL,
243 on the free list or in the queue. Anything else is an error. */
244
245 void
flush_ssaname_freelist(void)246 flush_ssaname_freelist (void)
247 {
248 /* If there were any SSA names released reset the SCEV cache. */
249 if (! vec_safe_is_empty (FREE_SSANAMES_QUEUE (cfun)))
250 scev_reset_htab ();
251 vec_safe_splice (FREE_SSANAMES (cfun), FREE_SSANAMES_QUEUE (cfun));
252 vec_safe_truncate (FREE_SSANAMES_QUEUE (cfun), 0);
253 }
254
255 /* Initialize SSA_NAME_IMM_USE_NODE of a SSA NAME. */
256
257 void
init_ssa_name_imm_use(tree name)258 init_ssa_name_imm_use (tree name)
259 {
260 use_operand_p imm;
261 imm = &(SSA_NAME_IMM_USE_NODE (name));
262 imm->use = NULL;
263 imm->prev = imm;
264 imm->next = imm;
265 imm->loc.ssa_name = name;
266 }
267
268 /* Return an SSA_NAME node for variable VAR defined in statement STMT
269 in function FN. STMT may be an empty statement for artificial
270 references (e.g., default definitions created when a variable is
271 used without a preceding definition). If VERISON is not zero then
272 allocate the SSA name with that version. */
273
274 tree
make_ssa_name_fn(struct function * fn,tree var,gimple * stmt,unsigned int version)275 make_ssa_name_fn (struct function *fn, tree var, gimple *stmt,
276 unsigned int version)
277 {
278 tree t;
279 gcc_assert (VAR_P (var)
280 || TREE_CODE (var) == PARM_DECL
281 || TREE_CODE (var) == RESULT_DECL
282 || (TYPE_P (var) && is_gimple_reg_type (var)));
283
284 /* Get the specified SSA name version. */
285 if (version != 0)
286 {
287 t = make_node (SSA_NAME);
288 SSA_NAME_VERSION (t) = version;
289 if (version >= SSANAMES (fn)->length ())
290 vec_safe_grow_cleared (SSANAMES (fn), version + 1);
291 gcc_assert ((*SSANAMES (fn))[version] == NULL);
292 (*SSANAMES (fn))[version] = t;
293 ssa_name_nodes_created++;
294 }
295 /* If our free list has an element, then use it. */
296 else if (!vec_safe_is_empty (FREE_SSANAMES (fn)))
297 {
298 t = FREE_SSANAMES (fn)->pop ();
299 ssa_name_nodes_reused++;
300
301 /* The node was cleared out when we put it on the free list, so
302 there is no need to do so again here. */
303 gcc_assert ((*SSANAMES (fn))[SSA_NAME_VERSION (t)] == NULL);
304 (*SSANAMES (fn))[SSA_NAME_VERSION (t)] = t;
305 }
306 else
307 {
308 t = make_node (SSA_NAME);
309 SSA_NAME_VERSION (t) = SSANAMES (fn)->length ();
310 vec_safe_push (SSANAMES (fn), t);
311 ssa_name_nodes_created++;
312 }
313
314 if (TYPE_P (var))
315 {
316 TREE_TYPE (t) = TYPE_MAIN_VARIANT (var);
317 SET_SSA_NAME_VAR_OR_IDENTIFIER (t, NULL_TREE);
318 }
319 else
320 {
321 TREE_TYPE (t) = TREE_TYPE (var);
322 SET_SSA_NAME_VAR_OR_IDENTIFIER (t, var);
323 }
324 SSA_NAME_DEF_STMT (t) = stmt;
325 if (POINTER_TYPE_P (TREE_TYPE (t)))
326 SSA_NAME_PTR_INFO (t) = NULL;
327 else
328 SSA_NAME_RANGE_INFO (t) = NULL;
329
330 SSA_NAME_IN_FREE_LIST (t) = 0;
331 SSA_NAME_IS_DEFAULT_DEF (t) = 0;
332 init_ssa_name_imm_use (t);
333
334 return t;
335 }
336
337 /* Helper function for set_range_info.
338
339 Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name
340 NAME. */
341
342 void
set_range_info_raw(tree name,enum value_range_kind range_type,const wide_int_ref & min,const wide_int_ref & max)343 set_range_info_raw (tree name, enum value_range_kind range_type,
344 const wide_int_ref &min, const wide_int_ref &max)
345 {
346 gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
347 gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
348 range_info_def *ri = SSA_NAME_RANGE_INFO (name);
349 unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
350
351 /* Allocate if not available. */
352 if (ri == NULL)
353 {
354 size_t size = (sizeof (range_info_def)
355 + trailing_wide_ints <3>::extra_size (precision));
356 ri = static_cast<range_info_def *> (ggc_internal_alloc (size));
357 ri->ints.set_precision (precision);
358 SSA_NAME_RANGE_INFO (name) = ri;
359 ri->set_nonzero_bits (wi::shwi (-1, precision));
360 }
361
362 /* Record the range type. */
363 if (SSA_NAME_RANGE_TYPE (name) != range_type)
364 SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
365
366 /* Set the values. */
367 ri->set_min (min);
368 ri->set_max (max);
369
370 /* If it is a range, try to improve nonzero_bits from the min/max. */
371 if (range_type == VR_RANGE)
372 {
373 wide_int xorv = ri->get_min () ^ ri->get_max ();
374 if (xorv != 0)
375 xorv = wi::mask (precision - wi::clz (xorv), false, precision);
376 ri->set_nonzero_bits (ri->get_nonzero_bits () & (ri->get_min () | xorv));
377 }
378 }
379
380 /* Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name
381 NAME while making sure we don't store useless range info. */
382
383 void
set_range_info(tree name,enum value_range_kind range_type,const wide_int_ref & min,const wide_int_ref & max)384 set_range_info (tree name, enum value_range_kind range_type,
385 const wide_int_ref &min, const wide_int_ref &max)
386 {
387 gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
388
389 /* A range of the entire domain is really no range at all. */
390 tree type = TREE_TYPE (name);
391 if (min == wi::min_value (TYPE_PRECISION (type), TYPE_SIGN (type))
392 && max == wi::max_value (TYPE_PRECISION (type), TYPE_SIGN (type)))
393 {
394 range_info_def *ri = SSA_NAME_RANGE_INFO (name);
395 if (ri == NULL)
396 return;
397 if (ri->get_nonzero_bits () == -1)
398 {
399 ggc_free (ri);
400 SSA_NAME_RANGE_INFO (name) = NULL;
401 return;
402 }
403 }
404
405 set_range_info_raw (name, range_type, min, max);
406 }
407
408 /* Store range information for NAME from a value_range. */
409
410 void
set_range_info(tree name,const value_range & vr)411 set_range_info (tree name, const value_range &vr)
412 {
413 wide_int min = wi::to_wide (vr.min ());
414 wide_int max = wi::to_wide (vr.max ());
415 set_range_info (name, vr.kind (), min, max);
416 }
417
418 /* Gets range information MIN, MAX and returns enum value_range_kind
419 corresponding to tree ssa_name NAME. enum value_range_kind returned
420 is used to determine if MIN and MAX are valid values. */
421
422 enum value_range_kind
get_range_info(const_tree name,wide_int * min,wide_int * max)423 get_range_info (const_tree name, wide_int *min, wide_int *max)
424 {
425 gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
426 gcc_assert (min && max);
427 range_info_def *ri = SSA_NAME_RANGE_INFO (name);
428
429 /* Return VR_VARYING for SSA_NAMEs with NULL RANGE_INFO or SSA_NAMEs
430 with integral types width > 2 * HOST_BITS_PER_WIDE_INT precision. */
431 if (!ri || (GET_MODE_PRECISION (SCALAR_INT_TYPE_MODE (TREE_TYPE (name)))
432 > 2 * HOST_BITS_PER_WIDE_INT))
433 return VR_VARYING;
434
435 *min = ri->get_min ();
436 *max = ri->get_max ();
437 return SSA_NAME_RANGE_TYPE (name);
438 }
439
440 /* Gets range information corresponding to ssa_name NAME and stores it
441 in a value_range VR. Returns the value_range_kind. */
442
443 enum value_range_kind
get_range_info(const_tree name,value_range & vr)444 get_range_info (const_tree name, value_range &vr)
445 {
446 tree min, max;
447 wide_int wmin, wmax;
448 enum value_range_kind kind = get_range_info (name, &wmin, &wmax);
449
450 if (kind == VR_VARYING)
451 vr.set_varying (TREE_TYPE (name));
452 else if (kind == VR_UNDEFINED)
453 vr.set_undefined ();
454 else
455 {
456 min = wide_int_to_tree (TREE_TYPE (name), wmin);
457 max = wide_int_to_tree (TREE_TYPE (name), wmax);
458 vr.set (min, max, kind);
459 }
460 return kind;
461 }
462
463 /* Set nonnull attribute to pointer NAME. */
464
465 void
set_ptr_nonnull(tree name)466 set_ptr_nonnull (tree name)
467 {
468 gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
469 struct ptr_info_def *pi = get_ptr_info (name);
470 pi->pt.null = 0;
471 }
472
473 /* Return nonnull attribute of pointer NAME. */
474 bool
get_ptr_nonnull(const_tree name)475 get_ptr_nonnull (const_tree name)
476 {
477 gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
478 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
479 if (pi == NULL)
480 return false;
481 /* TODO Now pt->null is conservatively set to true in PTA
482 analysis. vrp is the only pass (including ipa-vrp)
483 that clears pt.null via set_ptr_nonull when it knows
484 for sure. PTA will preserves the pt.null value set by VRP.
485
486 When PTA analysis is improved, pt.anything, pt.nonlocal
487 and pt.escaped may also has to be considered before
488 deciding that pointer cannot point to NULL. */
489 return !pi->pt.null;
490 }
491
492 /* Change non-zero bits bitmask of NAME. */
493
494 void
set_nonzero_bits(tree name,const wide_int_ref & mask)495 set_nonzero_bits (tree name, const wide_int_ref &mask)
496 {
497 gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
498 if (SSA_NAME_RANGE_INFO (name) == NULL)
499 {
500 if (mask == -1)
501 return;
502 set_range_info_raw (name, VR_RANGE,
503 wi::to_wide (TYPE_MIN_VALUE (TREE_TYPE (name))),
504 wi::to_wide (TYPE_MAX_VALUE (TREE_TYPE (name))));
505 }
506 range_info_def *ri = SSA_NAME_RANGE_INFO (name);
507 ri->set_nonzero_bits (mask);
508 }
509
510 /* Return a widest_int with potentially non-zero bits in SSA_NAME
511 NAME, the constant for INTEGER_CST, or -1 if unknown. */
512
513 wide_int
get_nonzero_bits(const_tree name)514 get_nonzero_bits (const_tree name)
515 {
516 if (TREE_CODE (name) == INTEGER_CST)
517 return wi::to_wide (name);
518
519 /* Use element_precision instead of TYPE_PRECISION so complex and
520 vector types get a non-zero precision. */
521 unsigned int precision = element_precision (TREE_TYPE (name));
522 if (POINTER_TYPE_P (TREE_TYPE (name)))
523 {
524 struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
525 if (pi && pi->align)
526 return wi::shwi (-(HOST_WIDE_INT) pi->align
527 | (HOST_WIDE_INT) pi->misalign, precision);
528 return wi::shwi (-1, precision);
529 }
530
531 range_info_def *ri = SSA_NAME_RANGE_INFO (name);
532 if (!ri)
533 return wi::shwi (-1, precision);
534
535 return ri->get_nonzero_bits ();
536 }
537
538 /* Return TRUE is OP, an SSA_NAME has a range of values [0..1], false
539 otherwise.
540
541 This can be because it is a boolean type, any unsigned integral
542 type with a single bit of precision, or has known range of [0..1]
543 via VRP analysis. */
544
545 bool
ssa_name_has_boolean_range(tree op)546 ssa_name_has_boolean_range (tree op)
547 {
548 gcc_assert (TREE_CODE (op) == SSA_NAME);
549
550 /* Boolean types always have a range [0..1]. */
551 if (TREE_CODE (TREE_TYPE (op)) == BOOLEAN_TYPE)
552 return true;
553
554 /* An integral type with a single bit of precision. */
555 if (INTEGRAL_TYPE_P (TREE_TYPE (op))
556 && TYPE_UNSIGNED (TREE_TYPE (op))
557 && TYPE_PRECISION (TREE_TYPE (op)) == 1)
558 return true;
559
560 /* An integral type with more precision, but the object
561 only takes on values [0..1] as determined by VRP
562 analysis. */
563 if (INTEGRAL_TYPE_P (TREE_TYPE (op))
564 && (TYPE_PRECISION (TREE_TYPE (op)) > 1)
565 && wi::eq_p (get_nonzero_bits (op), 1))
566 return true;
567
568 return false;
569 }
570
571 /* We no longer need the SSA_NAME expression VAR, release it so that
572 it may be reused.
573
574 Note it is assumed that no calls to make_ssa_name will be made
575 until all uses of the ssa name are released and that the only
576 use of the SSA_NAME expression is to check its SSA_NAME_VAR. All
577 other fields must be assumed clobbered. */
578
579 void
release_ssa_name_fn(struct function * fn,tree var)580 release_ssa_name_fn (struct function *fn, tree var)
581 {
582 if (!var)
583 return;
584
585 /* Never release the default definition for a symbol. It's a
586 special SSA name that should always exist once it's created. */
587 if (SSA_NAME_IS_DEFAULT_DEF (var))
588 return;
589
590 /* If VAR has been registered for SSA updating, don't remove it.
591 After update_ssa has run, the name will be released. */
592 if (name_registered_for_update_p (var))
593 {
594 release_ssa_name_after_update_ssa (var);
595 return;
596 }
597
598 /* release_ssa_name can be called multiple times on a single SSA_NAME.
599 However, it should only end up on our free list one time. We
600 keep a status bit in the SSA_NAME node itself to indicate it has
601 been put on the free list.
602
603 Note that once on the freelist you cannot reference the SSA_NAME's
604 defining statement. */
605 if (! SSA_NAME_IN_FREE_LIST (var))
606 {
607 int saved_ssa_name_version = SSA_NAME_VERSION (var);
608 use_operand_p imm = &(SSA_NAME_IMM_USE_NODE (var));
609
610 if (MAY_HAVE_DEBUG_BIND_STMTS)
611 insert_debug_temp_for_var_def (NULL, var);
612
613 if (flag_checking)
614 verify_imm_links (stderr, var);
615 while (imm->next != imm)
616 delink_imm_use (imm->next);
617
618 (*SSANAMES (fn))[SSA_NAME_VERSION (var)] = NULL_TREE;
619 memset (var, 0, tree_size (var));
620
621 imm->prev = imm;
622 imm->next = imm;
623 imm->loc.ssa_name = var;
624
625 /* First put back the right tree node so that the tree checking
626 macros do not complain. */
627 TREE_SET_CODE (var, SSA_NAME);
628
629 /* Restore the version number. */
630 SSA_NAME_VERSION (var) = saved_ssa_name_version;
631
632 /* Note this SSA_NAME is now in the first list. */
633 SSA_NAME_IN_FREE_LIST (var) = 1;
634
635 /* Put in a non-NULL TREE_TYPE so dumping code will not ICE
636 if it happens to come along a released SSA name and tries
637 to inspect its type. */
638 TREE_TYPE (var) = error_mark_node;
639
640 /* And finally queue it so that it will be put on the free list. */
641 vec_safe_push (FREE_SSANAMES_QUEUE (fn), var);
642 }
643 }
644
645 /* If the alignment of the pointer described by PI is known, return true and
646 store the alignment and the deviation from it into *ALIGNP and *MISALIGNP
647 respectively. Otherwise return false. */
648
649 bool
get_ptr_info_alignment(struct ptr_info_def * pi,unsigned int * alignp,unsigned int * misalignp)650 get_ptr_info_alignment (struct ptr_info_def *pi, unsigned int *alignp,
651 unsigned int *misalignp)
652 {
653 if (pi->align)
654 {
655 *alignp = pi->align;
656 *misalignp = pi->misalign;
657 return true;
658 }
659 else
660 return false;
661 }
662
663 /* State that the pointer described by PI has unknown alignment. */
664
665 void
mark_ptr_info_alignment_unknown(struct ptr_info_def * pi)666 mark_ptr_info_alignment_unknown (struct ptr_info_def *pi)
667 {
668 pi->align = 0;
669 pi->misalign = 0;
670 }
671
672 /* Store the power-of-two byte alignment and the deviation from that
673 alignment of pointer described by PI to ALIOGN and MISALIGN
674 respectively. */
675
676 void
set_ptr_info_alignment(struct ptr_info_def * pi,unsigned int align,unsigned int misalign)677 set_ptr_info_alignment (struct ptr_info_def *pi, unsigned int align,
678 unsigned int misalign)
679 {
680 gcc_checking_assert (align != 0);
681 gcc_assert ((align & (align - 1)) == 0);
682 gcc_assert ((misalign & ~(align - 1)) == 0);
683
684 pi->align = align;
685 pi->misalign = misalign;
686 }
687
688 /* If pointer described by PI has known alignment, increase its known
689 misalignment by INCREMENT modulo its current alignment. */
690
691 void
adjust_ptr_info_misalignment(struct ptr_info_def * pi,poly_uint64 increment)692 adjust_ptr_info_misalignment (struct ptr_info_def *pi, poly_uint64 increment)
693 {
694 if (pi->align != 0)
695 {
696 increment += pi->misalign;
697 if (!known_misalignment (increment, pi->align, &pi->misalign))
698 {
699 pi->align = known_alignment (increment);
700 pi->misalign = 0;
701 }
702 }
703 }
704
705 /* Return the alias information associated with pointer T. It creates a
706 new instance if none existed. */
707
708 struct ptr_info_def *
get_ptr_info(tree t)709 get_ptr_info (tree t)
710 {
711 struct ptr_info_def *pi;
712
713 gcc_assert (POINTER_TYPE_P (TREE_TYPE (t)));
714
715 pi = SSA_NAME_PTR_INFO (t);
716 if (pi == NULL)
717 {
718 pi = ggc_cleared_alloc<ptr_info_def> ();
719 pt_solution_reset (&pi->pt);
720 mark_ptr_info_alignment_unknown (pi);
721 SSA_NAME_PTR_INFO (t) = pi;
722 }
723
724 return pi;
725 }
726
727
728 /* Creates a new SSA name using the template NAME tobe defined by
729 statement STMT in function FN. */
730
731 tree
copy_ssa_name_fn(struct function * fn,tree name,gimple * stmt)732 copy_ssa_name_fn (struct function *fn, tree name, gimple *stmt)
733 {
734 tree new_name;
735
736 if (SSA_NAME_VAR (name))
737 new_name = make_ssa_name_fn (fn, SSA_NAME_VAR (name), stmt);
738 else
739 {
740 new_name = make_ssa_name_fn (fn, TREE_TYPE (name), stmt);
741 SET_SSA_NAME_VAR_OR_IDENTIFIER (new_name, SSA_NAME_IDENTIFIER (name));
742 }
743
744 return new_name;
745 }
746
747
748 /* Creates a duplicate of the ptr_info_def at PTR_INFO for use by
749 the SSA name NAME. */
750
751 void
duplicate_ssa_name_ptr_info(tree name,struct ptr_info_def * ptr_info)752 duplicate_ssa_name_ptr_info (tree name, struct ptr_info_def *ptr_info)
753 {
754 struct ptr_info_def *new_ptr_info;
755
756 gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
757 gcc_assert (!SSA_NAME_PTR_INFO (name));
758
759 if (!ptr_info)
760 return;
761
762 new_ptr_info = ggc_alloc<ptr_info_def> ();
763 *new_ptr_info = *ptr_info;
764
765 SSA_NAME_PTR_INFO (name) = new_ptr_info;
766 }
767
768 /* Creates a duplicate of the range_info_def at RANGE_INFO of type
769 RANGE_TYPE for use by the SSA name NAME. */
770 void
duplicate_ssa_name_range_info(tree name,enum value_range_kind range_type,struct range_info_def * range_info)771 duplicate_ssa_name_range_info (tree name, enum value_range_kind range_type,
772 struct range_info_def *range_info)
773 {
774 struct range_info_def *new_range_info;
775
776 gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
777 gcc_assert (!SSA_NAME_RANGE_INFO (name));
778
779 if (!range_info)
780 return;
781
782 unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
783 size_t size = (sizeof (range_info_def)
784 + trailing_wide_ints <3>::extra_size (precision));
785 new_range_info = static_cast<range_info_def *> (ggc_internal_alloc (size));
786 memcpy (new_range_info, range_info, size);
787
788 gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
789 SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
790 SSA_NAME_RANGE_INFO (name) = new_range_info;
791 }
792
793
794
795 /* Creates a duplicate of a ssa name NAME tobe defined by statement STMT
796 in function FN. */
797
798 tree
duplicate_ssa_name_fn(struct function * fn,tree name,gimple * stmt)799 duplicate_ssa_name_fn (struct function *fn, tree name, gimple *stmt)
800 {
801 tree new_name = copy_ssa_name_fn (fn, name, stmt);
802 if (POINTER_TYPE_P (TREE_TYPE (name)))
803 {
804 struct ptr_info_def *old_ptr_info = SSA_NAME_PTR_INFO (name);
805
806 if (old_ptr_info)
807 duplicate_ssa_name_ptr_info (new_name, old_ptr_info);
808 }
809 else
810 {
811 struct range_info_def *old_range_info = SSA_NAME_RANGE_INFO (name);
812
813 if (old_range_info)
814 duplicate_ssa_name_range_info (new_name, SSA_NAME_RANGE_TYPE (name),
815 old_range_info);
816 }
817
818 return new_name;
819 }
820
821
822 /* Reset all flow sensitive data on NAME such as range-info, nonzero
823 bits and alignment. */
824
825 void
reset_flow_sensitive_info(tree name)826 reset_flow_sensitive_info (tree name)
827 {
828 if (POINTER_TYPE_P (TREE_TYPE (name)))
829 {
830 /* points-to info is not flow-sensitive. */
831 if (SSA_NAME_PTR_INFO (name))
832 {
833 /* [E]VRP can derive context sensitive alignment info and
834 non-nullness properties. We must reset both. */
835 mark_ptr_info_alignment_unknown (SSA_NAME_PTR_INFO (name));
836 SSA_NAME_PTR_INFO (name)->pt.null = 1;
837 }
838 }
839 else
840 SSA_NAME_RANGE_INFO (name) = NULL;
841 }
842
843 /* Clear all flow sensitive data from all statements and PHI definitions
844 in BB. */
845
846 void
reset_flow_sensitive_info_in_bb(basic_block bb)847 reset_flow_sensitive_info_in_bb (basic_block bb)
848 {
849 for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);
850 gsi_next (&gsi))
851 {
852 gimple *stmt = gsi_stmt (gsi);
853 ssa_op_iter i;
854 tree op;
855 FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_DEF)
856 reset_flow_sensitive_info (op);
857 }
858
859 for (gphi_iterator gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
860 gsi_next (&gsi))
861 {
862 tree phi_def = gimple_phi_result (gsi.phi ());
863 reset_flow_sensitive_info (phi_def);
864 }
865 }
866
867 /* Release all the SSA_NAMEs created by STMT. */
868
869 void
release_defs(gimple * stmt)870 release_defs (gimple *stmt)
871 {
872 tree def;
873 ssa_op_iter iter;
874
875 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
876 if (TREE_CODE (def) == SSA_NAME)
877 release_ssa_name (def);
878 }
879
880
881 /* Replace the symbol associated with SSA_NAME with SYM. */
882
883 void
replace_ssa_name_symbol(tree ssa_name,tree sym)884 replace_ssa_name_symbol (tree ssa_name, tree sym)
885 {
886 SET_SSA_NAME_VAR_OR_IDENTIFIER (ssa_name, sym);
887 TREE_TYPE (ssa_name) = TREE_TYPE (sym);
888 }
889
890 /* Release the vector of free SSA_NAMEs and compact the vector of SSA_NAMEs
891 that are live. */
892
893 static void
release_free_names_and_compact_live_names(function * fun)894 release_free_names_and_compact_live_names (function *fun)
895 {
896 unsigned i, j;
897 int n = vec_safe_length (FREE_SSANAMES (fun));
898
899 /* Now release the freelist. */
900 vec_free (FREE_SSANAMES (fun));
901
902 /* And compact the SSA number space. We make sure to not change the
903 relative order of SSA versions. */
904 for (i = 1, j = 1; i < fun->gimple_df->ssa_names->length (); ++i)
905 {
906 tree name = ssa_name (i);
907 if (name)
908 {
909 if (i != j)
910 {
911 SSA_NAME_VERSION (name) = j;
912 (*fun->gimple_df->ssa_names)[j] = name;
913 }
914 j++;
915 }
916 }
917 fun->gimple_df->ssa_names->truncate (j);
918
919 statistics_counter_event (fun, "SSA names released", n);
920 statistics_counter_event (fun, "SSA name holes removed", i - j);
921 if (dump_file)
922 fprintf (dump_file, "Released %i names, %.2f%%, removed %i holes\n",
923 n, n * 100.0 / num_ssa_names, i - j);
924 }
925
926 /* Return SSA names that are unused to GGC memory and compact the SSA
927 version namespace. This is used to keep footprint of compiler during
928 interprocedural optimization. */
929
930 namespace {
931
932 const pass_data pass_data_release_ssa_names =
933 {
934 GIMPLE_PASS, /* type */
935 "release_ssa", /* name */
936 OPTGROUP_NONE, /* optinfo_flags */
937 TV_TREE_SSA_OTHER, /* tv_id */
938 PROP_ssa, /* properties_required */
939 0, /* properties_provided */
940 0, /* properties_destroyed */
941 TODO_remove_unused_locals, /* todo_flags_start */
942 0, /* todo_flags_finish */
943 };
944
945 class pass_release_ssa_names : public gimple_opt_pass
946 {
947 public:
pass_release_ssa_names(gcc::context * ctxt)948 pass_release_ssa_names (gcc::context *ctxt)
949 : gimple_opt_pass (pass_data_release_ssa_names, ctxt)
950 {}
951
952 /* opt_pass methods: */
953 virtual unsigned int execute (function *);
954
955 }; // class pass_release_ssa_names
956
957 unsigned int
execute(function * fun)958 pass_release_ssa_names::execute (function *fun)
959 {
960 release_free_names_and_compact_live_names (fun);
961 return 0;
962 }
963
964 } // anon namespace
965
966 gimple_opt_pass *
make_pass_release_ssa_names(gcc::context * ctxt)967 make_pass_release_ssa_names (gcc::context *ctxt)
968 {
969 return new pass_release_ssa_names (ctxt);
970 }
971