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1 /* Routines for performing Temporary Expression Replacement (TER) in SSA trees.
2 Copyright (C) 2003-2013 Free Software Foundation, Inc.
3 Contributed by Andrew MacLeod <amacleod@redhat.com>
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
10 any later version.
11
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
20
21
22 #include "config.h"
23 #include "system.h"
24 #include "coretypes.h"
25 #include "tm.h"
26 #include "tree.h"
27 #include "gimple-pretty-print.h"
28 #include "bitmap.h"
29 #include "basic-block.h"
30 #include "tree-ssa-alias.h"
31 #include "internal-fn.h"
32 #include "gimple-expr.h"
33 #include "is-a.h"
34 #include "gimple.h"
35 #include "gimple-iterator.h"
36 #include "gimple-ssa.h"
37 #include "tree-phinodes.h"
38 #include "ssa-iterators.h"
39 #include "stringpool.h"
40 #include "tree-ssanames.h"
41 #include "dumpfile.h"
42 #include "tree-ssa-live.h"
43 #include "tree-ssa-ter.h"
44 #include "tree-outof-ssa.h"
45 #include "flags.h"
46
47
48 /* Temporary Expression Replacement (TER)
49
50 Replace SSA version variables during out-of-ssa with their defining
51 expression if there is only one use of the variable.
52
53 This pass is required in order for the RTL expansion pass to see larger
54 chunks of code. This allows it to make better choices on RTL pattern
55 selection. When expand is rewritten and merged with out-of-ssa, and
56 understands SSA, this should be eliminated.
57
58 A pass is made through the function, one block at a time. No cross block
59 information is tracked.
60
61 Variables which only have one use, and whose defining stmt is considered
62 a replaceable expression (see ssa_is_replaceable_p) are tracked to see whether
63 they can be replaced at their use location.
64
65 n_12 = C * 10
66 a_2 = b_5 + 6
67 v_9 = a_2 * n_12
68
69 if there are the only use of n_12 and a_2, TER will substitute in their
70 expressions in v_9, and end up with:
71
72 v_9 = (b_5 + 6) * (C * 10)
73
74 which will then have the ssa_name assigned to regular variables, and the
75 resulting code which will be passed to the expander looks something like:
76
77 v = (b + 6) * (C * 10)
78
79
80 This requires ensuring that none of the variables used by the expression
81 change between the def point and where it is used. Furthermore, if any
82 of the ssa_names used in this expression are themselves replaceable, we
83 have to ensure none of that expressions' arguments change either.
84 Although SSA_NAMES themselves don't change, this pass is performed after
85 coalescing has coalesced different SSA_NAMES together, so there could be a
86 definition of an SSA_NAME which is coalesced with a use that causes a
87 problem, i.e.,
88
89 PHI b_5 = <b_8(2), b_14(1)>
90 <...>
91 a_2 = b_5 + 6
92 b_8 = c_4 + 4
93 v_9 = a_2 * n_12
94 <...>
95
96 If b_5, b_8 and b_14 are all coalesced together...
97 The expression b_5 + 6 CANNOT replace the use in the statement defining v_9
98 because b_8 is in fact killing the value of b_5 since they share a partition
99 and will be assigned the same memory or register location.
100
101 TER implements this but stepping through the instructions in a block and
102 tracking potential expressions for replacement, and the partitions they are
103 dependent on. Expressions are represented by the SSA_NAME_VERSION of the
104 DEF on the LHS of a GIMPLE_ASSIGN and the expression is the RHS.
105
106 When a stmt is determined to be a possible replacement expression, the
107 following steps are taken:
108
109 EXPR_DECL_UID bitmap is allocated and set to the base variable UID of the
110 def and any uses in the expression. non-NULL means the expression is being
111 tracked. The UID's themselves are used to prevent TER substitution into
112 accumulating sequences, i.e.,
113
114 x = x + y
115 x = x + z
116 x = x + w
117 etc.
118 this can result in very large expressions which don't accomplish anything
119 see PR tree-optimization/17549.
120
121 PARTITION_DEPENDENCIES is another bitmap array, and it has a bit set for any
122 partition which is used in the expression. This is primarily used to remove
123 an expression from the partition kill lists when a decision is made whether
124 to replace it or not. This is indexed by ssa version number as well, and
125 indicates a partition number. virtual operands are not tracked individually,
126 but they are summarized by an artificial partition called VIRTUAL_PARTITION.
127 This means a MAY or MUST def will kill *ALL* expressions that are dependent
128 on a virtual operand.
129 Note that the EXPR_DECL_UID and this bitmap represent very similar
130 information, but the info in one is not easy to obtain from the other.
131
132 KILL_LIST is yet another bitmap array, this time it is indexed by partition
133 number, and represents a list of active expressions which will will no
134 longer be valid if a definition into this partition takes place.
135
136 PARTITION_IN_USE is simply a bitmap which is used to track which partitions
137 currently have something in their kill list. This is used at the end of
138 a block to clear out the KILL_LIST bitmaps at the end of each block.
139
140 NEW_REPLACEABLE_DEPENDENCIES is used as a temporary place to store
141 dependencies which will be reused by the current definition. All the uses
142 on an expression are processed before anything else is done. If a use is
143 determined to be a replaceable expression AND the current stmt is also going
144 to be replaceable, all the dependencies of this replaceable use will be
145 picked up by the current stmt's expression. Rather than recreate them, they
146 are simply copied here and then copied into the new expression when it is
147 processed.
148
149 a_2 = b_5 + 6
150 v_8 = a_2 + c_4
151
152 a_2's expression 'b_5 + 6' is determined to be replaceable at the use
153 location. It is dependent on the partition 'b_5' is in. This is cached into
154 the NEW_REPLACEABLE_DEPENDENCIES bitmap, and when v_8 is examined for
155 replaceability, it is a candidate, and it is dependent on the partition
156 b_5 is in *NOT* a_2, as well as c_4's partition.
157
158 if v_8 is also replaceable:
159
160 x_9 = v_8 * 5
161
162 x_9 is dependent on partitions b_5, and c_4
163
164 if a statement is found which has either of those partitions written to
165 before x_9 is used, then x_9 itself is NOT replaceable. */
166
167
168 /* Temporary Expression Replacement (TER) table information. */
169
170 typedef struct temp_expr_table_d
171 {
172 var_map map;
173 bitmap *partition_dependencies; /* Partitions expr is dependent on. */
174 bitmap replaceable_expressions; /* Replacement expression table. */
175 bitmap *expr_decl_uids; /* Base uids of exprs. */
176 bitmap *kill_list; /* Expr's killed by a partition. */
177 int virtual_partition; /* Pseudo partition for virtual ops. */
178 bitmap partition_in_use; /* Partitions with kill entries. */
179 bitmap new_replaceable_dependencies; /* Holding place for pending dep's. */
180 int *num_in_part; /* # of ssa_names in a partition. */
181 int *call_cnt; /* Call count at definition. */
182 } *temp_expr_table_p;
183
184 /* Used to indicate a dependency on VDEFs. */
185 #define VIRTUAL_PARTITION(table) (table->virtual_partition)
186
187 /* A place for the many, many bitmaps we create. */
188 static bitmap_obstack ter_bitmap_obstack;
189
190 #ifdef ENABLE_CHECKING
191 extern void debug_ter (FILE *, temp_expr_table_p);
192 #endif
193
194
195 /* Create a new TER table for MAP. */
196
197 static temp_expr_table_p
198 new_temp_expr_table (var_map map)
199 {
200 temp_expr_table_p t;
201 unsigned x;
202
203 t = XNEW (struct temp_expr_table_d);
204 t->map = map;
205
206 t->partition_dependencies = XCNEWVEC (bitmap, num_ssa_names + 1);
207 t->expr_decl_uids = XCNEWVEC (bitmap, num_ssa_names + 1);
208 t->kill_list = XCNEWVEC (bitmap, num_var_partitions (map) + 1);
209
210 t->partition_in_use = BITMAP_ALLOC (&ter_bitmap_obstack);
211
212 t->virtual_partition = num_var_partitions (map);
213 t->new_replaceable_dependencies = BITMAP_ALLOC (&ter_bitmap_obstack);
214
215 t->replaceable_expressions = NULL;
216 t->num_in_part = XCNEWVEC (int, num_var_partitions (map));
217 for (x = 1; x < num_ssa_names; x++)
218 {
219 int p;
220 tree name = ssa_name (x);
221 if (!name)
222 continue;
223 p = var_to_partition (map, name);
224 if (p != NO_PARTITION)
225 t->num_in_part[p]++;
226 }
227 t->call_cnt = XCNEWVEC (int, num_ssa_names + 1);
228
229 return t;
230 }
231
232
233 /* Free TER table T. If there are valid replacements, return the expression
234 vector. */
235
236 static bitmap
237 free_temp_expr_table (temp_expr_table_p t)
238 {
239 bitmap ret = NULL;
240
241 #ifdef ENABLE_CHECKING
242 unsigned x;
243 for (x = 0; x <= num_var_partitions (t->map); x++)
244 gcc_assert (!t->kill_list[x]);
245 for (x = 0; x < num_ssa_names; x++)
246 {
247 gcc_assert (t->expr_decl_uids[x] == NULL);
248 gcc_assert (t->partition_dependencies[x] == NULL);
249 }
250 #endif
251
252 BITMAP_FREE (t->partition_in_use);
253 BITMAP_FREE (t->new_replaceable_dependencies);
254
255 free (t->expr_decl_uids);
256 free (t->kill_list);
257 free (t->partition_dependencies);
258 free (t->num_in_part);
259 free (t->call_cnt);
260
261 if (t->replaceable_expressions)
262 ret = t->replaceable_expressions;
263
264 free (t);
265 return ret;
266 }
267
268
269 /* Return TRUE if VERSION is to be replaced by an expression in TAB. */
270
271 static inline bool
272 version_to_be_replaced_p (temp_expr_table_p tab, int version)
273 {
274 if (!tab->replaceable_expressions)
275 return false;
276 return bitmap_bit_p (tab->replaceable_expressions, version);
277 }
278
279
280 /* Add partition P to the list if partitions VERSION is dependent on. TAB is
281 the expression table */
282
283 static inline void
284 make_dependent_on_partition (temp_expr_table_p tab, int version, int p)
285 {
286 if (!tab->partition_dependencies[version])
287 tab->partition_dependencies[version] = BITMAP_ALLOC (&ter_bitmap_obstack);
288
289 bitmap_set_bit (tab->partition_dependencies[version], p);
290 }
291
292
293 /* Add VER to the kill list for P. TAB is the expression table */
294
295 static inline void
296 add_to_partition_kill_list (temp_expr_table_p tab, int p, int ver)
297 {
298 if (!tab->kill_list[p])
299 {
300 tab->kill_list[p] = BITMAP_ALLOC (&ter_bitmap_obstack);
301 bitmap_set_bit (tab->partition_in_use, p);
302 }
303 bitmap_set_bit (tab->kill_list[p], ver);
304 }
305
306
307 /* Remove VER from the partition kill list for P. TAB is the expression
308 table. */
309
310 static inline void
311 remove_from_partition_kill_list (temp_expr_table_p tab, int p, int version)
312 {
313 gcc_checking_assert (tab->kill_list[p]);
314 bitmap_clear_bit (tab->kill_list[p], version);
315 if (bitmap_empty_p (tab->kill_list[p]))
316 {
317 bitmap_clear_bit (tab->partition_in_use, p);
318 BITMAP_FREE (tab->kill_list[p]);
319 }
320 }
321
322
323 /* Add a dependency between the def of ssa VERSION and VAR. If VAR is
324 replaceable by an expression, add a dependence each of the elements of the
325 expression. These are contained in the new_replaceable list. TAB is the
326 expression table. */
327
328 static void
329 add_dependence (temp_expr_table_p tab, int version, tree var)
330 {
331 int i;
332 bitmap_iterator bi;
333 unsigned x;
334
335 i = SSA_NAME_VERSION (var);
336 if (version_to_be_replaced_p (tab, i))
337 {
338 if (!bitmap_empty_p (tab->new_replaceable_dependencies))
339 {
340 /* Version will now be killed by a write to any partition the
341 substituted expression would have been killed by. */
342 EXECUTE_IF_SET_IN_BITMAP (tab->new_replaceable_dependencies, 0, x, bi)
343 add_to_partition_kill_list (tab, x, version);
344
345 /* Rather than set partition_dependencies and in_use lists bit by
346 bit, simply OR in the new_replaceable_dependencies bits. */
347 if (!tab->partition_dependencies[version])
348 tab->partition_dependencies[version] =
349 BITMAP_ALLOC (&ter_bitmap_obstack);
350 bitmap_ior_into (tab->partition_dependencies[version],
351 tab->new_replaceable_dependencies);
352 bitmap_ior_into (tab->partition_in_use,
353 tab->new_replaceable_dependencies);
354 /* It is only necessary to add these once. */
355 bitmap_clear (tab->new_replaceable_dependencies);
356 }
357 }
358 else
359 {
360 i = var_to_partition (tab->map, var);
361 gcc_checking_assert (i != NO_PARTITION);
362 gcc_checking_assert (tab->num_in_part[i] != 0);
363 /* Only dependencies on ssa_names which are coalesced with something need
364 to be tracked. Partitions with containing only a single SSA_NAME
365 *cannot* have their value changed. */
366 if (tab->num_in_part[i] > 1)
367 {
368 add_to_partition_kill_list (tab, i, version);
369 make_dependent_on_partition (tab, version, i);
370 }
371 }
372 }
373
374
375 /* This function will remove the expression for VERSION from replacement
376 consideration in table TAB. If FREE_EXPR is true, then remove the
377 expression from consideration as well by freeing the decl uid bitmap. */
378
379 static void
380 finished_with_expr (temp_expr_table_p tab, int version, bool free_expr)
381 {
382 unsigned i;
383 bitmap_iterator bi;
384
385 /* Remove this expression from its dependent lists. The partition dependence
386 list is retained and transferred later to whomever uses this version. */
387 if (tab->partition_dependencies[version])
388 {
389 EXECUTE_IF_SET_IN_BITMAP (tab->partition_dependencies[version], 0, i, bi)
390 remove_from_partition_kill_list (tab, i, version);
391 BITMAP_FREE (tab->partition_dependencies[version]);
392 }
393 if (free_expr)
394 BITMAP_FREE (tab->expr_decl_uids[version]);
395 }
396
397
398 /* Return TRUE if expression STMT is suitable for replacement.
399 In addition to ssa_is_replaceable_p, require the same bb, and for -O0
400 same locus and same BLOCK), Considers memory loads as replaceable if aliasing
401 is available. */
402
403 static inline bool
404 ter_is_replaceable_p (gimple stmt)
405 {
406
407 if (ssa_is_replaceable_p (stmt))
408 {
409 use_operand_p use_p;
410 tree def;
411 gimple use_stmt;
412 location_t locus1, locus2;
413 tree block1, block2;
414
415 /* Only consider definitions which have a single use. ssa_is_replaceable_p
416 already performed this check, but the use stmt pointer is required for
417 further checks. */
418 def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF);
419 if (!single_imm_use (def, &use_p, &use_stmt))
420 return false;
421
422 /* If the use isn't in this block, it wont be replaced either. */
423 if (gimple_bb (use_stmt) != gimple_bb (stmt))
424 return false;
425
426 locus1 = gimple_location (stmt);
427 block1 = LOCATION_BLOCK (locus1);
428 locus1 = LOCATION_LOCUS (locus1);
429
430 if (gimple_code (use_stmt) == GIMPLE_PHI)
431 locus2 = gimple_phi_arg_location (use_stmt,
432 PHI_ARG_INDEX_FROM_USE (use_p));
433 else
434 locus2 = gimple_location (use_stmt);
435 block2 = LOCATION_BLOCK (locus2);
436 locus2 = LOCATION_LOCUS (locus2);
437
438 if ((!optimize || optimize_debug)
439 && ((locus1 != UNKNOWN_LOCATION && locus1 != locus2)
440 || (block1 != NULL_TREE && block1 != block2)))
441 return false;
442
443 /* Without alias info we can't move around loads. */
444 if (!optimize && gimple_assign_single_p (stmt)
445 && !is_gimple_val (gimple_assign_rhs1 (stmt)))
446 return false;
447
448 return true;
449 }
450 return false;
451 }
452
453
454 /* Create an expression entry for a replaceable expression. */
455
456 static void
457 process_replaceable (temp_expr_table_p tab, gimple stmt, int call_cnt)
458 {
459 tree var, def, basevar;
460 int version;
461 ssa_op_iter iter;
462 bitmap def_vars, use_vars;
463
464 gcc_checking_assert (ter_is_replaceable_p (stmt));
465
466 def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF);
467 version = SSA_NAME_VERSION (def);
468 def_vars = BITMAP_ALLOC (&ter_bitmap_obstack);
469
470 basevar = SSA_NAME_VAR (def);
471 if (basevar)
472 bitmap_set_bit (def_vars, DECL_UID (basevar));
473
474 /* Add this expression to the dependency list for each use partition. */
475 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
476 {
477 int var_version = SSA_NAME_VERSION (var);
478
479 use_vars = tab->expr_decl_uids[var_version];
480 add_dependence (tab, version, var);
481 if (use_vars)
482 {
483 bitmap_ior_into (def_vars, use_vars);
484 BITMAP_FREE (tab->expr_decl_uids[var_version]);
485 }
486 else if (SSA_NAME_VAR (var))
487 bitmap_set_bit (def_vars, DECL_UID (SSA_NAME_VAR (var)));
488 }
489 tab->expr_decl_uids[version] = def_vars;
490
491 /* If there are VUSES, add a dependence on virtual defs. */
492 if (gimple_vuse (stmt))
493 {
494 make_dependent_on_partition (tab, version, VIRTUAL_PARTITION (tab));
495 add_to_partition_kill_list (tab, VIRTUAL_PARTITION (tab), version);
496 }
497
498 tab->call_cnt[version] = call_cnt;
499 }
500
501
502 /* This function removes any expression in TAB which is dependent on PARTITION
503 from consideration, making it not replaceable. */
504
505 static inline void
506 kill_expr (temp_expr_table_p tab, int partition)
507 {
508 unsigned version;
509
510 /* Mark every active expr dependent on this var as not replaceable.
511 finished_with_expr can modify the bitmap, so we can't execute over it. */
512 while (tab->kill_list[partition])
513 {
514 version = bitmap_first_set_bit (tab->kill_list[partition]);
515 finished_with_expr (tab, version, true);
516 }
517
518 gcc_checking_assert (!tab->kill_list[partition]);
519 }
520
521
522 /* This function kills all expressions in TAB which are dependent on virtual
523 partitions. */
524
525 static inline void
526 kill_virtual_exprs (temp_expr_table_p tab)
527 {
528 kill_expr (tab, VIRTUAL_PARTITION (tab));
529 }
530
531
532 /* Mark the expression associated with VAR as replaceable, and enter
533 the defining stmt into the partition_dependencies table TAB. If
534 MORE_REPLACING is true, accumulate the pending partition dependencies. */
535
536 static void
537 mark_replaceable (temp_expr_table_p tab, tree var, bool more_replacing)
538 {
539 int version = SSA_NAME_VERSION (var);
540
541 /* Move the dependence list to the pending listpending. */
542 if (more_replacing && tab->partition_dependencies[version])
543 bitmap_ior_into (tab->new_replaceable_dependencies,
544 tab->partition_dependencies[version]);
545
546 finished_with_expr (tab, version, !more_replacing);
547
548 /* Set the replaceable expression.
549 The bitmap for this "escapes" from this file so it's allocated
550 on the default obstack. */
551 if (!tab->replaceable_expressions)
552 tab->replaceable_expressions = BITMAP_ALLOC (NULL);
553 bitmap_set_bit (tab->replaceable_expressions, version);
554 }
555
556
557 /* This function processes basic block BB, and looks for variables which can
558 be replaced by their expressions. Results are stored in the table TAB. */
559
560 static void
561 find_replaceable_in_bb (temp_expr_table_p tab, basic_block bb)
562 {
563 gimple_stmt_iterator bsi;
564 gimple stmt;
565 tree def, use, fndecl;
566 int partition;
567 var_map map = tab->map;
568 ssa_op_iter iter;
569 bool stmt_replaceable;
570 int cur_call_cnt = 0;
571
572 for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
573 {
574 stmt = gsi_stmt (bsi);
575
576 if (is_gimple_debug (stmt))
577 continue;
578
579 stmt_replaceable = ter_is_replaceable_p (stmt);
580
581 /* Determine if this stmt finishes an existing expression. */
582 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
583 {
584 unsigned ver = SSA_NAME_VERSION (use);
585
586 /* If this use is a potential replacement variable, process it. */
587 if (tab->expr_decl_uids[ver])
588 {
589 bool same_root_var = false;
590 ssa_op_iter iter2;
591 bitmap vars = tab->expr_decl_uids[ver];
592
593 /* See if the root variables are the same. If they are, we
594 do not want to do the replacement to avoid problems with
595 code size, see PR tree-optimization/17549. */
596 if (!bitmap_empty_p (vars))
597 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter2, SSA_OP_DEF)
598 {
599 if (SSA_NAME_VAR (def)
600 && bitmap_bit_p (vars, DECL_UID (SSA_NAME_VAR (def))))
601 {
602 same_root_var = true;
603 break;
604 }
605 }
606
607 /* If the stmt does a memory store and the replacement
608 is a load aliasing it avoid creating overlapping
609 assignments which we cannot expand correctly. */
610 if (gimple_vdef (stmt))
611 {
612 gimple def_stmt = SSA_NAME_DEF_STMT (use);
613 while (is_gimple_assign (def_stmt)
614 && gimple_assign_rhs_code (def_stmt) == SSA_NAME)
615 def_stmt
616 = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (def_stmt));
617 if (gimple_vuse (def_stmt)
618 && gimple_assign_single_p (def_stmt)
619 && stmt_may_clobber_ref_p (stmt,
620 gimple_assign_rhs1 (def_stmt)))
621 same_root_var = true;
622 }
623
624 /* Mark expression as replaceable unless stmt is volatile, or the
625 def variable has the same root variable as something in the
626 substitution list, or the def and use span a call such that
627 we'll expand lifetimes across a call. */
628 if (gimple_has_volatile_ops (stmt) || same_root_var
629 || (tab->call_cnt[ver] != cur_call_cnt
630 && SINGLE_SSA_USE_OPERAND (SSA_NAME_DEF_STMT (use), SSA_OP_USE)
631 == NULL_USE_OPERAND_P))
632 finished_with_expr (tab, ver, true);
633 else
634 mark_replaceable (tab, use, stmt_replaceable);
635 }
636 }
637
638 /* Next, see if this stmt kills off an active expression. */
639 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
640 {
641 partition = var_to_partition (map, def);
642 if (partition != NO_PARTITION && tab->kill_list[partition])
643 kill_expr (tab, partition);
644 }
645
646 /* Increment counter if this is a non BUILT_IN call. We allow
647 replacement over BUILT_IN calls since many will expand to inline
648 insns instead of a true call. */
649 if (is_gimple_call (stmt)
650 && !((fndecl = gimple_call_fndecl (stmt))
651 && DECL_BUILT_IN (fndecl)))
652 cur_call_cnt++;
653
654 /* Now see if we are creating a new expression or not. */
655 if (stmt_replaceable)
656 process_replaceable (tab, stmt, cur_call_cnt);
657
658 /* Free any unused dependency lists. */
659 bitmap_clear (tab->new_replaceable_dependencies);
660
661 /* A V_{MAY,MUST}_DEF kills any expression using a virtual operand,
662 including the current stmt. */
663 if (gimple_vdef (stmt))
664 kill_virtual_exprs (tab);
665 }
666 }
667
668
669 /* This function is the driver routine for replacement of temporary expressions
670 in the SSA->normal phase, operating on MAP. If there are replaceable
671 expressions, a table is returned which maps SSA versions to the
672 expressions they should be replaced with. A NULL_TREE indicates no
673 replacement should take place. If there are no replacements at all,
674 NULL is returned by the function, otherwise an expression vector indexed
675 by SSA_NAME version numbers. */
676
677 bitmap
678 find_replaceable_exprs (var_map map)
679 {
680 basic_block bb;
681 temp_expr_table_p table;
682 bitmap ret;
683
684 bitmap_obstack_initialize (&ter_bitmap_obstack);
685 table = new_temp_expr_table (map);
686 FOR_EACH_BB_FN (bb, cfun)
687 {
688 find_replaceable_in_bb (table, bb);
689 gcc_checking_assert (bitmap_empty_p (table->partition_in_use));
690 }
691 ret = free_temp_expr_table (table);
692 bitmap_obstack_release (&ter_bitmap_obstack);
693 return ret;
694 }
695
696 /* Dump TER expression table EXPR to file F. */
697
698 void
699 dump_replaceable_exprs (FILE *f, bitmap expr)
700 {
701 tree var;
702 unsigned x;
703
704 fprintf (f, "\nReplacing Expressions\n");
705 for (x = 0; x < num_ssa_names; x++)
706 if (bitmap_bit_p (expr, x))
707 {
708 var = ssa_name (x);
709 print_generic_expr (f, var, TDF_SLIM);
710 fprintf (f, " replace with --> ");
711 print_gimple_stmt (f, SSA_NAME_DEF_STMT (var), 0, TDF_SLIM);
712 fprintf (f, "\n");
713 }
714 fprintf (f, "\n");
715 }
716
717
718 #ifdef ENABLE_CHECKING
719 /* Dump the status of the various tables in the expression table. This is used
720 exclusively to debug TER. F is the place to send debug info and T is the
721 table being debugged. */
722
723 DEBUG_FUNCTION void
724 debug_ter (FILE *f, temp_expr_table_p t)
725 {
726 unsigned x, y;
727 bitmap_iterator bi;
728
729 fprintf (f, "\nDumping current state of TER\n virtual partition = %d\n",
730 VIRTUAL_PARTITION (t));
731 if (t->replaceable_expressions)
732 dump_replaceable_exprs (f, t->replaceable_expressions);
733 fprintf (f, "Currently tracking the following expressions:\n");
734
735 for (x = 1; x < num_ssa_names; x++)
736 if (t->expr_decl_uids[x])
737 {
738 print_generic_expr (f, ssa_name (x), TDF_SLIM);
739 fprintf (f, " dep-parts : ");
740 if (t->partition_dependencies[x]
741 && !bitmap_empty_p (t->partition_dependencies[x]))
742 {
743 EXECUTE_IF_SET_IN_BITMAP (t->partition_dependencies[x], 0, y, bi)
744 fprintf (f, "P%d ",y);
745 }
746 fprintf (f, " basedecls: ");
747 EXECUTE_IF_SET_IN_BITMAP (t->expr_decl_uids[x], 0, y, bi)
748 fprintf (f, "%d ",y);
749 fprintf (f, " call_cnt : %d",t->call_cnt[x]);
750 fprintf (f, "\n");
751 }
752
753 bitmap_print (f, t->partition_in_use, "Partitions in use ",
754 "\npartition KILL lists:\n");
755
756 for (x = 0; x <= num_var_partitions (t->map); x++)
757 if (t->kill_list[x])
758 {
759 fprintf (f, "Partition %d : ", x);
760 EXECUTE_IF_SET_IN_BITMAP (t->kill_list[x], 0, y, bi)
761 fprintf (f, "_%d ",y);
762 }
763
764 fprintf (f, "\n----------\n");
765 }
766 #endif
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