1/* Routines for performing Temporary Expression Replacement (TER) in SSA trees.
2 Copyright (C) 2003-2017 Free Software Foundation, Inc.
3 Contributed by Andrew MacLeod <amacleod@redhat.com>
4
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify
8it under the terms of the GNU General Public License as published by
9the Free Software Foundation; either version 3, or (at your option)
10any later version.
11
12GCC is distributed in the hope that it will be useful,
13but WITHOUT ANY WARRANTY; without even the implied warranty of
14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15GNU General Public License for more details.
16
17You should have received a copy of the GNU General Public License
18along 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 "backend.h"
26#include "tree.h"
27#include "gimple.h"
28#include "ssa.h"
29#include "gimple-pretty-print.h"
30#include "gimple-iterator.h"
31#include "dumpfile.h"
32#include "tree-ssa-live.h"
33#include "tree-ssa-ter.h"
34#include "tree-outof-ssa.h"
35#include "gimple-walk.h"
36
37
38/* Temporary Expression Replacement (TER)
39
40 Replace SSA version variables during out-of-ssa with their defining
41 expression if there is only one use of the variable.
42
43 This pass is required in order for the RTL expansion pass to see larger
44 chunks of code. This allows it to make better choices on RTL pattern
45 selection. When expand is rewritten and merged with out-of-ssa, and
46 understands SSA, this should be eliminated.
47
48 A pass is made through the function, one block at a time. No cross block
49 information is tracked.
50
51 Variables which only have one use, and whose defining stmt is considered
52 a replaceable expression (see ssa_is_replaceable_p) are tracked to see whether
53 they can be replaced at their use location.
54
55 n_12 = C * 10
56 a_2 = b_5 + 6
57 v_9 = a_2 * n_12
58
59 if there are the only use of n_12 and a_2, TER will substitute in their
60 expressions in v_9, and end up with:
61
62 v_9 = (b_5 + 6) * (C * 10)
63
64 which will then have the ssa_name assigned to regular variables, and the
65 resulting code which will be passed to the expander looks something like:
66
67 v = (b + 6) * (C * 10)
68
69
70 This requires ensuring that none of the variables used by the expression
71 change between the def point and where it is used. Furthermore, if any
72 of the ssa_names used in this expression are themselves replaceable, we
73 have to ensure none of that expressions' arguments change either.
74 Although SSA_NAMES themselves don't change, this pass is performed after
75 coalescing has coalesced different SSA_NAMES together, so there could be a
76 definition of an SSA_NAME which is coalesced with a use that causes a
77 problem, i.e.,
78
79 PHI b_5 = <b_8(2), b_14(1)>
80 <...>
81 a_2 = b_5 + 6
82 b_8 = c_4 + 4
83 v_9 = a_2 * n_12
84 <...>
85
86 If b_5, b_8 and b_14 are all coalesced together...
87 The expression b_5 + 6 CANNOT replace the use in the statement defining v_9
88 because b_8 is in fact killing the value of b_5 since they share a partition
89 and will be assigned the same memory or register location.
90
91 TER implements this but stepping through the instructions in a block and
92 tracking potential expressions for replacement, and the partitions they are
93 dependent on. Expressions are represented by the SSA_NAME_VERSION of the
94 DEF on the LHS of a GIMPLE_ASSIGN and the expression is the RHS.
95
96 When a stmt is determined to be a possible replacement expression, the
97 following steps are taken:
98
99 EXPR_DECL_UID bitmap is allocated and set to the base variable UID of the
100 def and any uses in the expression. non-NULL means the expression is being
101 tracked. The UID's themselves are used to prevent TER substitution into
102 accumulating sequences, i.e.,
103
104 x = x + y
105 x = x + z
106 x = x + w
107 etc.
108 this can result in very large expressions which don't accomplish anything
109 see PR tree-optimization/17549.
110
111 PARTITION_DEPENDENCIES is another bitmap array, and it has a bit set for any
112 partition which is used in the expression. This is primarily used to remove
113 an expression from the partition kill lists when a decision is made whether
114 to replace it or not. This is indexed by ssa version number as well, and
115 indicates a partition number. virtual operands are not tracked individually,
116 but they are summarized by an artificial partition called VIRTUAL_PARTITION.
117 This means a MAY or MUST def will kill *ALL* expressions that are dependent
118 on a virtual operand.
119 Note that the EXPR_DECL_UID and this bitmap represent very similar
120 information, but the info in one is not easy to obtain from the other.
121
122 KILL_LIST is yet another bitmap array, this time it is indexed by partition
123 number, and represents a list of active expressions which will no
124 longer be valid if a definition into this partition takes place.
125
126 PARTITION_IN_USE is simply a bitmap which is used to track which partitions
127 currently have something in their kill list. This is used at the end of
128 a block to clear out the KILL_LIST bitmaps at the end of each block.
129
130 NEW_REPLACEABLE_DEPENDENCIES is used as a temporary place to store
131 dependencies which will be reused by the current definition. All the uses
132 on an expression are processed before anything else is done. If a use is
133 determined to be a replaceable expression AND the current stmt is also going
134 to be replaceable, all the dependencies of this replaceable use will be
135 picked up by the current stmt's expression. Rather than recreate them, they
136 are simply copied here and then copied into the new expression when it is
137 processed.
138
139 a_2 = b_5 + 6
140 v_8 = a_2 + c_4
141
142 a_2's expression 'b_5 + 6' is determined to be replaceable at the use
143 location. It is dependent on the partition 'b_5' is in. This is cached into
144 the NEW_REPLACEABLE_DEPENDENCIES bitmap, and when v_8 is examined for
145 replaceability, it is a candidate, and it is dependent on the partition
146 b_5 is in *NOT* a_2, as well as c_4's partition.
147
148 if v_8 is also replaceable:
149
150 x_9 = v_8 * 5
151
152 x_9 is dependent on partitions b_5, and c_4
153
154 if a statement is found which has either of those partitions written to
155 before x_9 is used, then x_9 itself is NOT replaceable. */
156
157
158/* Temporary Expression Replacement (TER) table information. */
159
160struct temp_expr_table
161{
162 var_map map;
163 bitmap *partition_dependencies; /* Partitions expr is dependent on. */
164 bitmap replaceable_expressions; /* Replacement expression table. */
165 bitmap *expr_decl_uids; /* Base uids of exprs. */
166 bitmap *kill_list; /* Expr's killed by a partition. */
167 int virtual_partition; /* Pseudo partition for virtual ops. */
168 bitmap partition_in_use; /* Partitions with kill entries. */
169 bitmap new_replaceable_dependencies; /* Holding place for pending dep's. */
170 int *num_in_part; /* # of ssa_names in a partition. */
171 int *call_cnt; /* Call count at definition. */
172 int *reg_vars_cnt; /* Number of register variable
173 definitions encountered. */
174};
175
176/* Used to indicate a dependency on VDEFs. */
177#define VIRTUAL_PARTITION(table) (table->virtual_partition)
178
179/* A place for the many, many bitmaps we create. */
180static bitmap_obstack ter_bitmap_obstack;
181
182extern void debug_ter (FILE *, temp_expr_table *);
183
184
185/* Create a new TER table for MAP. */
186
187static temp_expr_table *
188new_temp_expr_table (var_map map)
189{
190 temp_expr_table *t = XNEW (struct temp_expr_table);
191 t->map = map;
192
193 t->partition_dependencies = XCNEWVEC (bitmap, num_ssa_names + 1);
194 t->expr_decl_uids = XCNEWVEC (bitmap, num_ssa_names + 1);
195 t->kill_list = XCNEWVEC (bitmap, num_var_partitions (map) + 1);
196
197 t->partition_in_use = BITMAP_ALLOC (&ter_bitmap_obstack);
198
199 t->virtual_partition = num_var_partitions (map);
200 t->new_replaceable_dependencies = BITMAP_ALLOC (&ter_bitmap_obstack);
201
202 t->replaceable_expressions = NULL;
203 t->num_in_part = XCNEWVEC (int, num_var_partitions (map));
204
205 unsigned x;
206 tree name;
207
208 FOR_EACH_SSA_NAME (x, name, cfun)
209 {
210 int p;
211 p = var_to_partition (map, name);
212 if (p != NO_PARTITION)
213 t->num_in_part[p]++;
214 }
215 t->call_cnt = XCNEWVEC (int, num_ssa_names + 1);
216 t->reg_vars_cnt = XCNEWVEC (int, num_ssa_names + 1);
217
218 return t;
219}
220
221
222/* Free TER table T. If there are valid replacements, return the expression
223 vector. */
224
225static bitmap
226free_temp_expr_table (temp_expr_table *t)
227{
228 bitmap ret = NULL;
229
230 if (flag_checking)
231 {
232 for (unsigned x = 0; x <= num_var_partitions (t->map); x++)
233 gcc_assert (!t->kill_list[x]);
234 for (unsigned x = 0; x < num_ssa_names; x++)
235 {
236 gcc_assert (t->expr_decl_uids[x] == NULL);
237 gcc_assert (t->partition_dependencies[x] == NULL);
238 }
239 }
240
241 BITMAP_FREE (t->partition_in_use);
242 BITMAP_FREE (t->new_replaceable_dependencies);
243
244 free (t->expr_decl_uids);
245 free (t->kill_list);
246 free (t->partition_dependencies);
247 free (t->num_in_part);
248 free (t->call_cnt);
249 free (t->reg_vars_cnt);
250
251 if (t->replaceable_expressions)
252 ret = t->replaceable_expressions;
253
254 free (t);
255 return ret;
256}
257
258
259/* Return TRUE if VERSION is to be replaced by an expression in TAB. */
260
261static inline bool
262version_to_be_replaced_p (temp_expr_table *tab, int version)
263{
264 if (!tab->replaceable_expressions)
265 return false;
266 return bitmap_bit_p (tab->replaceable_expressions, version);
267}
268
269
270/* Add partition P to the list if partitions VERSION is dependent on. TAB is
271 the expression table */
272
273static inline void
274make_dependent_on_partition (temp_expr_table *tab, int version, int p)
275{
276 if (!tab->partition_dependencies[version])
277 tab->partition_dependencies[version] = BITMAP_ALLOC (&ter_bitmap_obstack);
278
279 bitmap_set_bit (tab->partition_dependencies[version], p);
280}
281
282
283/* Add VER to the kill list for P. TAB is the expression table */
284
285static inline void
286add_to_partition_kill_list (temp_expr_table *tab, int p, int ver)
287{
288 if (!tab->kill_list[p])
289 {
290 tab->kill_list[p] = BITMAP_ALLOC (&ter_bitmap_obstack);
291 bitmap_set_bit (tab->partition_in_use, p);
292 }
293 bitmap_set_bit (tab->kill_list[p], ver);
294}
295
296
297/* Remove VER from the partition kill list for P. TAB is the expression
298 table. */
299
300static inline void
301remove_from_partition_kill_list (temp_expr_table *tab, int p, int version)
302{
303 gcc_checking_assert (tab->kill_list[p]);
304 bitmap_clear_bit (tab->kill_list[p], version);
305 if (bitmap_empty_p (tab->kill_list[p]))
306 {
307 bitmap_clear_bit (tab->partition_in_use, p);
308 BITMAP_FREE (tab->kill_list[p]);
309 }
310}
311
312
313/* Add a dependency between the def of ssa VERSION and VAR. If VAR is
314 replaceable by an expression, add a dependence each of the elements of the
315 expression. These are contained in the new_replaceable list. TAB is the
316 expression table. */
317
318static void
319add_dependence (temp_expr_table *tab, int version, tree var)
320{
321 int i;
322 bitmap_iterator bi;
323 unsigned x;
324
325 i = SSA_NAME_VERSION (var);
326 if (version_to_be_replaced_p (tab, i))
327 {
328 if (!bitmap_empty_p (tab->new_replaceable_dependencies))
329 {
330 /* Version will now be killed by a write to any partition the
331 substituted expression would have been killed by. */
332 EXECUTE_IF_SET_IN_BITMAP (tab->new_replaceable_dependencies, 0, x, bi)
333 add_to_partition_kill_list (tab, x, version);
334
335 /* Rather than set partition_dependencies and in_use lists bit by
336 bit, simply OR in the new_replaceable_dependencies bits. */
337 if (!tab->partition_dependencies[version])
338 tab->partition_dependencies[version] =
339 BITMAP_ALLOC (&ter_bitmap_obstack);
340 bitmap_ior_into (tab->partition_dependencies[version],
341 tab->new_replaceable_dependencies);
342 bitmap_ior_into (tab->partition_in_use,
343 tab->new_replaceable_dependencies);
344 /* It is only necessary to add these once. */
345 bitmap_clear (tab->new_replaceable_dependencies);
346 }
347 }
348 else
349 {
350 i = var_to_partition (tab->map, var);
351 gcc_checking_assert (i != NO_PARTITION);
352 gcc_checking_assert (tab->num_in_part[i] != 0);
353 /* Only dependencies on ssa_names which are coalesced with something need
354 to be tracked. Partitions with containing only a single SSA_NAME
355 *cannot* have their value changed. */
356 if (tab->num_in_part[i] > 1)
357 {
358 add_to_partition_kill_list (tab, i, version);
359 make_dependent_on_partition (tab, version, i);
360 }
361 }
362}
363
364
365/* This function will remove the expression for VERSION from replacement
366 consideration in table TAB. If FREE_EXPR is true, then remove the
367 expression from consideration as well by freeing the decl uid bitmap. */
368
369static void
370finished_with_expr (temp_expr_table *tab, int version, bool free_expr)
371{
372 unsigned i;
373 bitmap_iterator bi;
374
375 /* Remove this expression from its dependent lists. The partition dependence
376 list is retained and transferred later to whomever uses this version. */
377 if (tab->partition_dependencies[version])
378 {
379 EXECUTE_IF_SET_IN_BITMAP (tab->partition_dependencies[version], 0, i, bi)
380 remove_from_partition_kill_list (tab, i, version);
381 BITMAP_FREE (tab->partition_dependencies[version]);
382 }
383 if (free_expr)
384 BITMAP_FREE (tab->expr_decl_uids[version]);
385}
386
387
388/* Return TRUE if expression STMT is suitable for replacement.
389 In addition to ssa_is_replaceable_p, require the same bb, and for -O0
390 same locus and same BLOCK), Considers memory loads as replaceable if aliasing
391 is available. */
392
393static inline bool
394ter_is_replaceable_p (gimple *stmt)
395{
396
397 if (ssa_is_replaceable_p (stmt))
398 {
399 use_operand_p use_p;
400 tree def;
401 gimple *use_stmt;
402 location_t locus1, locus2;
403 tree block1, block2;
404
405 /* Only consider definitions which have a single use. ssa_is_replaceable_p
406 already performed this check, but the use stmt pointer is required for
407 further checks. */
408 def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF);
409 if (!single_imm_use (def, &use_p, &use_stmt))
410 return false;
411
412 /* If the use isn't in this block, it wont be replaced either. */
413 if (gimple_bb (use_stmt) != gimple_bb (stmt))
414 return false;
415
416 locus1 = gimple_location (stmt);
417 block1 = LOCATION_BLOCK (locus1);
418 locus1 = LOCATION_LOCUS (locus1);
419
420 if (gphi *phi = dyn_cast <gphi *> (use_stmt))
421 locus2 = gimple_phi_arg_location (phi,
422 PHI_ARG_INDEX_FROM_USE (use_p));
423 else
424 locus2 = gimple_location (use_stmt);
425 block2 = LOCATION_BLOCK (locus2);
426 locus2 = LOCATION_LOCUS (locus2);
427
428 if ((!optimize || optimize_debug)
429 && ((locus1 != UNKNOWN_LOCATION && locus1 != locus2)
430 || (block1 != NULL_TREE && block1 != block2)))
431 return false;
432
433 return true;
434 }
435 return false;
436}
437
438
439/* Create an expression entry for a replaceable expression. */
440
441static void
442process_replaceable (temp_expr_table *tab, gimple *stmt, int call_cnt,
443 int reg_vars_cnt)
444{
445 tree var, def, basevar;
446 int version;
447 ssa_op_iter iter;
448 bitmap def_vars, use_vars;
449
450 gcc_checking_assert (ter_is_replaceable_p (stmt));
451
452 def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF);
453 version = SSA_NAME_VERSION (def);
454 def_vars = BITMAP_ALLOC (&ter_bitmap_obstack);
455
456 basevar = SSA_NAME_VAR (def);
457 if (basevar)
458 bitmap_set_bit (def_vars, DECL_UID (basevar));
459
460 /* Add this expression to the dependency list for each use partition. */
461 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
462 {
463 int var_version = SSA_NAME_VERSION (var);
464
465 use_vars = tab->expr_decl_uids[var_version];
466 add_dependence (tab, version, var);
467 if (use_vars)
468 {
469 bitmap_ior_into (def_vars, use_vars);
470 BITMAP_FREE (tab->expr_decl_uids[var_version]);
471 }
472 else if (SSA_NAME_VAR (var))
473 bitmap_set_bit (def_vars, DECL_UID (SSA_NAME_VAR (var)));
474 }
475 tab->expr_decl_uids[version] = def_vars;
476
477 /* If there are VUSES, add a dependence on virtual defs. */
478 if (gimple_vuse (stmt))
479 {
480 make_dependent_on_partition (tab, version, VIRTUAL_PARTITION (tab));
481 add_to_partition_kill_list (tab, VIRTUAL_PARTITION (tab), version);
482 }
483
484 tab->call_cnt[version] = call_cnt;
485 tab->reg_vars_cnt[version] = reg_vars_cnt;
486}
487
488
489/* This function removes any expression in TAB which is dependent on PARTITION
490 from consideration, making it not replaceable. */
491
492static inline void
493kill_expr (temp_expr_table *tab, int partition)
494{
495 unsigned version;
496
497 /* Mark every active expr dependent on this var as not replaceable.
498 finished_with_expr can modify the bitmap, so we can't execute over it. */
499 while (tab->kill_list[partition])
500 {
501 version = bitmap_first_set_bit (tab->kill_list[partition]);
502 finished_with_expr (tab, version, true);
503 }
504
505 gcc_checking_assert (!tab->kill_list[partition]);
506}
507
508
509/* This function kills all expressions in TAB which are dependent on virtual
510 partitions. */
511
512static inline void
513kill_virtual_exprs (temp_expr_table *tab)
514{
515 kill_expr (tab, VIRTUAL_PARTITION (tab));
516}
517
518
519/* Mark the expression associated with VAR as replaceable, and enter
520 the defining stmt into the partition_dependencies table TAB. If
521 MORE_REPLACING is true, accumulate the pending partition dependencies. */
522
523static void
524mark_replaceable (temp_expr_table *tab, tree var, bool more_replacing)
525{
526 int version = SSA_NAME_VERSION (var);
527
528 /* Move the dependence list to the pending listpending. */
529 if (more_replacing && tab->partition_dependencies[version])
530 bitmap_ior_into (tab->new_replaceable_dependencies,
531 tab->partition_dependencies[version]);
532
533 finished_with_expr (tab, version, !more_replacing);
534
535 /* Set the replaceable expression.
536 The bitmap for this "escapes" from this file so it's allocated
537 on the default obstack. */
538 if (!tab->replaceable_expressions)
539 tab->replaceable_expressions = BITMAP_ALLOC (NULL);
540 bitmap_set_bit (tab->replaceable_expressions, version);
541}
542
543
544/* Helper function for find_ssaname_in_stores. Called via walk_tree to
545 find a SSA_NAME DATA somewhere in *TP. */
546
547static tree
548find_ssaname (tree *tp, int *walk_subtrees, void *data)
549{
550 tree var = (tree) data;
551 if (*tp == var)
552 return var;
553 else if (IS_TYPE_OR_DECL_P (*tp))
554 *walk_subtrees = 0;
555 return NULL_TREE;
556}
557
558/* Helper function for find_replaceable_in_bb. Return true if SSA_NAME DATA
559 is used somewhere in T, which is a store in the statement. Called via
560 walk_stmt_load_store_addr_ops. */
561
562static bool
563find_ssaname_in_store (gimple *, tree, tree t, void *data)
564{
565 return walk_tree (&t, find_ssaname, data, NULL) != NULL_TREE;
566}
567
568/* This function processes basic block BB, and looks for variables which can
569 be replaced by their expressions. Results are stored in the table TAB. */
570
571static void
572find_replaceable_in_bb (temp_expr_table *tab, basic_block bb)
573{
574 gimple_stmt_iterator bsi;
575 gimple *stmt;
576 tree def, use, fndecl;
577 int partition;
578 var_map map = tab->map;
579 ssa_op_iter iter;
580 bool stmt_replaceable;
581 int cur_call_cnt = 0;
582 int cur_reg_vars_cnt = 0;
583
584 for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
585 {
586 stmt = gsi_stmt (bsi);
587
588 if (is_gimple_debug (stmt))
589 continue;
590
591 stmt_replaceable = ter_is_replaceable_p (stmt);
592
593 /* Determine if this stmt finishes an existing expression. */
594 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
595 {
596 unsigned ver = SSA_NAME_VERSION (use);
597
598 /* If this use is a potential replacement variable, process it. */
599 if (tab->expr_decl_uids[ver])
600 {
601 bool same_root_var = false;
602 ssa_op_iter iter2;
603 bitmap vars = tab->expr_decl_uids[ver];
604
605 /* See if the root variables are the same. If they are, we
606 do not want to do the replacement to avoid problems with
607 code size, see PR tree-optimization/17549. */
608 if (!bitmap_empty_p (vars))
609 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter2, SSA_OP_DEF)
610 {
611 if (SSA_NAME_VAR (def)
612 && bitmap_bit_p (vars, DECL_UID (SSA_NAME_VAR (def))))
613 {
614 same_root_var = true;
615 break;
616 }
617 }
618
619 /* If the stmt does a memory store and the replacement
620 is a load aliasing it avoid creating overlapping
621 assignments which we cannot expand correctly. */
622 if (gimple_vdef (stmt))
623 {
624 gimple *def_stmt = SSA_NAME_DEF_STMT (use);
625 while (is_gimple_assign (def_stmt)
626 && gimple_assign_rhs_code (def_stmt) == SSA_NAME)
627 def_stmt
628 = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (def_stmt));
629 if (gimple_vuse (def_stmt)
630 && gimple_assign_single_p (def_stmt)
631 && stmt_may_clobber_ref_p (stmt,
632 gimple_assign_rhs1 (def_stmt)))
633 {
634 /* For calls, it is not a problem if USE is among
635 call's arguments or say OBJ_TYPE_REF argument,
636 all those necessarily need to be evaluated before
637 the call that may clobber the memory. But if
638 LHS of the call refers to USE, expansion might
639 evaluate it after the call, prevent TER in that
640 case.
641 For inline asm, allow TER of loads into input
642 arguments, but disallow TER for USEs that occur
643 somewhere in outputs. */
644 if (is_gimple_call (stmt)
645 || gimple_code (stmt) == GIMPLE_ASM)
646 {
647 if (walk_stmt_load_store_ops (stmt, use, NULL,
648 find_ssaname_in_store))
649 same_root_var = true;
650 }
651 else
652 same_root_var = true;
653 }
654 }
655
656 /* Mark expression as replaceable unless stmt is volatile, or the
657 def variable has the same root variable as something in the
658 substitution list, or the def and use span a call such that
659 we'll expand lifetimes across a call. We also don't want to
660 replace across these expressions that may call libcalls that
661 clobber the register involved. See PR 70184. */
662 if (gimple_has_volatile_ops (stmt) || same_root_var
663 || (tab->call_cnt[ver] != cur_call_cnt
664 && SINGLE_SSA_USE_OPERAND (SSA_NAME_DEF_STMT (use), SSA_OP_USE)
665 == NULL_USE_OPERAND_P)
666 || tab->reg_vars_cnt[ver] != cur_reg_vars_cnt)
667 finished_with_expr (tab, ver, true);
668 else
669 mark_replaceable (tab, use, stmt_replaceable);
670 }
671 }
672
673 /* Next, see if this stmt kills off an active expression. */
674 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
675 {
676 partition = var_to_partition (map, def);
677 if (partition != NO_PARTITION && tab->kill_list[partition])
678 kill_expr (tab, partition);
679 }
680
681 /* Increment counter if this is a non BUILT_IN call. We allow
682 replacement over BUILT_IN calls since many will expand to inline
683 insns instead of a true call. */
684 if (is_gimple_call (stmt)
685 && !((fndecl = gimple_call_fndecl (stmt))
686 && DECL_BUILT_IN (fndecl)))
687 cur_call_cnt++;
688
689 /* Increment counter if this statement sets a local
690 register variable. */
691 if (gimple_assign_single_p (stmt)
692 && (TREE_CODE (gimple_assign_lhs (stmt)) == VAR_DECL
693 && DECL_HARD_REGISTER (gimple_assign_lhs (stmt))))
694 cur_reg_vars_cnt++;
695
696 /* Now see if we are creating a new expression or not. */
697 if (stmt_replaceable)
698 process_replaceable (tab, stmt, cur_call_cnt, cur_reg_vars_cnt);
699
700 /* Free any unused dependency lists. */
701 bitmap_clear (tab->new_replaceable_dependencies);
702
703 /* A V_{MAY,MUST}_DEF kills any expression using a virtual operand,
704 including the current stmt. */
705 if (gimple_vdef (stmt))
706 kill_virtual_exprs (tab);
707 }
708}
709
710
711/* This function is the driver routine for replacement of temporary expressions
712 in the SSA->normal phase, operating on MAP. If there are replaceable
713 expressions, a table is returned which maps SSA versions to the
714 expressions they should be replaced with. A NULL_TREE indicates no
715 replacement should take place. If there are no replacements at all,
716 NULL is returned by the function, otherwise an expression vector indexed
717 by SSA_NAME version numbers. */
718
719bitmap
720find_replaceable_exprs (var_map map)
721{
722 basic_block bb;
723 temp_expr_table *table;
724 bitmap ret;
725
726 bitmap_obstack_initialize (&ter_bitmap_obstack);
727 table = new_temp_expr_table (map);
728 FOR_EACH_BB_FN (bb, cfun)
729 {
730 find_replaceable_in_bb (table, bb);
731 gcc_checking_assert (bitmap_empty_p (table->partition_in_use));
732 }
733 ret = free_temp_expr_table (table);
734 bitmap_obstack_release (&ter_bitmap_obstack);
735 return ret;
736}
737
738/* Dump TER expression table EXPR to file F. */
739
740void
741dump_replaceable_exprs (FILE *f, bitmap expr)
742{
743 tree var;
744 unsigned x;
745
746 fprintf (f, "\nReplacing Expressions\n");
747 for (x = 0; x < num_ssa_names; x++)
748 if (bitmap_bit_p (expr, x))
749 {
750 var = ssa_name (x);
751 print_generic_expr (f, var, TDF_SLIM);
752 fprintf (f, " replace with --> ");
753 print_gimple_stmt (f, SSA_NAME_DEF_STMT (var), 0, TDF_SLIM);
754 fprintf (f, "\n");
755 }
756 fprintf (f, "\n");
757}
758
759
760/* Dump the status of the various tables in the expression table. This is used
761 exclusively to debug TER. F is the place to send debug info and T is the
762 table being debugged. */
763
764DEBUG_FUNCTION void
765debug_ter (FILE *f, temp_expr_table *t)
766{
767 unsigned x, y;
768 bitmap_iterator bi;
769
770 fprintf (f, "\nDumping current state of TER\n virtual partition = %d\n",
771 VIRTUAL_PARTITION (t));
772 if (t->replaceable_expressions)
773 dump_replaceable_exprs (f, t->replaceable_expressions);
774 fprintf (f, "Currently tracking the following expressions:\n");
775
776 for (x = 1; x < num_ssa_names; x++)
777 if (t->expr_decl_uids[x])
778 {
779 print_generic_expr (f, ssa_name (x), TDF_SLIM);
780 fprintf (f, " dep-parts : ");
781 if (t->partition_dependencies[x]
782 && !bitmap_empty_p (t->partition_dependencies[x]))
783 {
784 EXECUTE_IF_SET_IN_BITMAP (t->partition_dependencies[x], 0, y, bi)
785 fprintf (f, "P%d ",y);
786 }
787 fprintf (f, " basedecls: ");
788 EXECUTE_IF_SET_IN_BITMAP (t->expr_decl_uids[x], 0, y, bi)
789 fprintf (f, "%d ",y);
790 fprintf (f, " call_cnt : %d",t->call_cnt[x]);
791 fprintf (f, "\n");
792 }
793
794 bitmap_print (f, t->partition_in_use, "Partitions in use ",
795 "\npartition KILL lists:\n");
796
797 for (x = 0; x <= num_var_partitions (t->map); x++)
798 if (t->kill_list[x])
799 {
800 fprintf (f, "Partition %d : ", x);
801 EXECUTE_IF_SET_IN_BITMAP (t->kill_list[x], 0, y, bi)
802 fprintf (f, "_%d ",y);
803 }
804
805 fprintf (f, "\n----------\n");
806}
807