2012-12-01 Alessandro Fanfarillo <alessandro.fanfarillo@gmail.com>
[official-gcc.git] / gcc / tree-ssa-ter.c
blob3375a2777c990aeb3abaab83dc32233bdd426d1c
1 /* Routines for performing Temporary Expression Replacement (TER) in SSA trees.
2 Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
3 Free Software Foundation, Inc.
4 Contributed by Andrew MacLeod <amacleod@redhat.com>
6 This file is part of GCC.
8 GCC 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.
13 GCC 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.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
23 #include "config.h"
24 #include "system.h"
25 #include "coretypes.h"
26 #include "tm.h"
27 #include "tree.h"
28 #include "gimple-pretty-print.h"
29 #include "bitmap.h"
30 #include "tree-flow.h"
31 #include "dumpfile.h"
32 #include "tree-ssa-live.h"
33 #include "flags.h"
36 /* Temporary Expression Replacement (TER)
38 Replace SSA version variables during out-of-ssa with their defining
39 expression if there is only one use of the variable.
41 This pass is required in order for the RTL expansion pass to see larger
42 chunks of code. This allows it to make better choices on RTL pattern
43 selection. When expand is rewritten and merged with out-of-ssa, and
44 understands SSA, this should be eliminated.
46 A pass is made through the function, one block at a time. No cross block
47 information is tracked.
49 Variables which only have one use, and whose defining stmt is considered
50 a replaceable expression (see is_replaceable_p) are tracked to see whether
51 they can be replaced at their use location.
53 n_12 = C * 10
54 a_2 = b_5 + 6
55 v_9 = a_2 * n_12
57 if there are the only use of n_12 and a_2, TER will substitute in their
58 expressions in v_9, and end up with:
60 v_9 = (b_5 + 6) * (C * 10)
62 which will then have the ssa_name assigned to regular variables, and the
63 resulting code which will be passed to the expander looks something like:
65 v = (b + 6) * (C * 10)
68 This requires ensuring that none of the variables used by the expression
69 change between the def point and where it is used. Furthermore, if any
70 of the ssa_names used in this expression are themselves replaceable, we
71 have to ensure none of that expressions' arguments change either.
72 Although SSA_NAMES themselves don't change, this pass is performed after
73 coalescing has coalesced different SSA_NAMES together, so there could be a
74 definition of an SSA_NAME which is coalesced with a use that causes a
75 problem, i.e.,
77 PHI b_5 = <b_8(2), b_14(1)>
78 <...>
79 a_2 = b_5 + 6
80 b_8 = c_4 + 4
81 v_9 = a_2 * n_12
82 <...>
84 If b_5, b_8 and b_14 are all coalesced together...
85 The expression b_5 + 6 CANNOT replace the use in the statement defining v_9
86 because b_8 is in fact killing the value of b_5 since they share a partition
87 and will be assigned the same memory or register location.
89 TER implements this but stepping through the instructions in a block and
90 tracking potential expressions for replacement, and the partitions they are
91 dependent on. Expressions are represented by the SSA_NAME_VERSION of the
92 DEF on the LHS of a GIMPLE_ASSIGN and the expression is the RHS.
94 When a stmt is determined to be a possible replacement expression, the
95 following steps are taken:
97 EXPR_DECL_UID bitmap is allocated and set to the base variable UID of the
98 def and any uses in the expression. non-NULL means the expression is being
99 tracked. The UID's themselves are used to prevent TER substitution into
100 accumulating sequences, i.e.,
102 x = x + y
103 x = x + z
104 x = x + w
105 etc.
106 this can result in very large expressions which don't accomplish anything
107 see PR tree-optimization/17549.
109 PARTITION_DEPENDENCIES is another bitmap array, and it has a bit set for any
110 partition which is used in the expression. This is primarily used to remove
111 an expression from the partition kill lists when a decision is made whether
112 to replace it or not. This is indexed by ssa version number as well, and
113 indicates a partition number. virtual operands are not tracked individually,
114 but they are summarized by an artificial partition called VIRTUAL_PARTITION.
115 This means a MAY or MUST def will kill *ALL* expressions that are dependent
116 on a virtual operand.
117 Note that the EXPR_DECL_UID and this bitmap represent very similar
118 information, but the info in one is not easy to obtain from the other.
120 KILL_LIST is yet another bitmap array, this time it is indexed by partition
121 number, and represents a list of active expressions which will will no
122 longer be valid if a definition into this partition takes place.
124 PARTITION_IN_USE is simply a bitmap which is used to track which partitions
125 currently have something in their kill list. This is used at the end of
126 a block to clear out the KILL_LIST bitmaps at the end of each block.
128 NEW_REPLACEABLE_DEPENDENCIES is used as a temporary place to store
129 dependencies which will be reused by the current definition. All the uses
130 on an expression are processed before anything else is done. If a use is
131 determined to be a replaceable expression AND the current stmt is also going
132 to be replaceable, all the dependencies of this replaceable use will be
133 picked up by the current stmt's expression. Rather than recreate them, they
134 are simply copied here and then copied into the new expression when it is
135 processed.
137 a_2 = b_5 + 6
138 v_8 = a_2 + c_4
140 a_2's expression 'b_5 + 6' is determined to be replaceable at the use
141 location. It is dependent on the partition 'b_5' is in. This is cached into
142 the NEW_REPLACEABLE_DEPENDENCIES bitmap, and when v_8 is examined for
143 replaceability, it is a candidate, and it is dependent on the partition
144 b_5 is in *NOT* a_2, as well as c_4's partition.
146 if v_8 is also replaceable:
148 x_9 = v_8 * 5
150 x_9 is dependent on partitions b_5, and c_4
152 if a statement is found which has either of those partitions written to
153 before x_9 is used, then x_9 itself is NOT replaceable. */
156 /* Temporary Expression Replacement (TER) table information. */
158 typedef struct temp_expr_table_d
160 var_map map;
161 bitmap *partition_dependencies; /* Partitions expr is dependent on. */
162 bitmap replaceable_expressions; /* Replacement expression table. */
163 bitmap *expr_decl_uids; /* Base uids of exprs. */
164 bitmap *kill_list; /* Expr's killed by a partition. */
165 int virtual_partition; /* Pseudo partition for virtual ops. */
166 bitmap partition_in_use; /* Partitions with kill entries. */
167 bitmap new_replaceable_dependencies; /* Holding place for pending dep's. */
168 int *num_in_part; /* # of ssa_names in a partition. */
169 int *call_cnt; /* Call count at definition. */
170 } *temp_expr_table_p;
172 /* Used to indicate a dependency on VDEFs. */
173 #define VIRTUAL_PARTITION(table) (table->virtual_partition)
175 /* A place for the many, many bitmaps we create. */
176 static bitmap_obstack ter_bitmap_obstack;
178 #ifdef ENABLE_CHECKING
179 extern void debug_ter (FILE *, temp_expr_table_p);
180 #endif
183 /* Create a new TER table for MAP. */
185 static temp_expr_table_p
186 new_temp_expr_table (var_map map)
188 temp_expr_table_p t;
189 unsigned x;
191 t = XNEW (struct temp_expr_table_d);
192 t->map = map;
194 t->partition_dependencies = XCNEWVEC (bitmap, num_ssa_names + 1);
195 t->expr_decl_uids = XCNEWVEC (bitmap, num_ssa_names + 1);
196 t->kill_list = XCNEWVEC (bitmap, num_var_partitions (map) + 1);
198 t->partition_in_use = BITMAP_ALLOC (&ter_bitmap_obstack);
200 t->virtual_partition = num_var_partitions (map);
201 t->new_replaceable_dependencies = BITMAP_ALLOC (&ter_bitmap_obstack);
203 t->replaceable_expressions = NULL;
204 t->num_in_part = XCNEWVEC (int, num_var_partitions (map));
205 for (x = 1; x < num_ssa_names; x++)
207 int p;
208 tree name = ssa_name (x);
209 if (!name)
210 continue;
211 p = var_to_partition (map, name);
212 if (p != NO_PARTITION)
213 t->num_in_part[p]++;
215 t->call_cnt = XCNEWVEC (int, num_ssa_names + 1);
217 return t;
221 /* Free TER table T. If there are valid replacements, return the expression
222 vector. */
224 static bitmap
225 free_temp_expr_table (temp_expr_table_p t)
227 bitmap ret = NULL;
229 #ifdef ENABLE_CHECKING
230 unsigned x;
231 for (x = 0; x <= num_var_partitions (t->map); x++)
232 gcc_assert (!t->kill_list[x]);
233 for (x = 0; x < num_ssa_names; x++)
235 gcc_assert (t->expr_decl_uids[x] == NULL);
236 gcc_assert (t->partition_dependencies[x] == NULL);
238 #endif
240 BITMAP_FREE (t->partition_in_use);
241 BITMAP_FREE (t->new_replaceable_dependencies);
243 free (t->expr_decl_uids);
244 free (t->kill_list);
245 free (t->partition_dependencies);
246 free (t->num_in_part);
247 free (t->call_cnt);
249 if (t->replaceable_expressions)
250 ret = t->replaceable_expressions;
252 free (t);
253 return ret;
257 /* Return TRUE if VERSION is to be replaced by an expression in TAB. */
259 static inline bool
260 version_to_be_replaced_p (temp_expr_table_p tab, int version)
262 if (!tab->replaceable_expressions)
263 return false;
264 return bitmap_bit_p (tab->replaceable_expressions, version);
268 /* Add partition P to the list if partitions VERSION is dependent on. TAB is
269 the expression table */
271 static inline void
272 make_dependent_on_partition (temp_expr_table_p tab, int version, int p)
274 if (!tab->partition_dependencies[version])
275 tab->partition_dependencies[version] = BITMAP_ALLOC (&ter_bitmap_obstack);
277 bitmap_set_bit (tab->partition_dependencies[version], p);
281 /* Add VER to the kill list for P. TAB is the expression table */
283 static inline void
284 add_to_partition_kill_list (temp_expr_table_p tab, int p, int ver)
286 if (!tab->kill_list[p])
288 tab->kill_list[p] = BITMAP_ALLOC (&ter_bitmap_obstack);
289 bitmap_set_bit (tab->partition_in_use, p);
291 bitmap_set_bit (tab->kill_list[p], ver);
295 /* Remove VER from the partition kill list for P. TAB is the expression
296 table. */
298 static inline void
299 remove_from_partition_kill_list (temp_expr_table_p tab, int p, int version)
301 gcc_checking_assert (tab->kill_list[p]);
302 bitmap_clear_bit (tab->kill_list[p], version);
303 if (bitmap_empty_p (tab->kill_list[p]))
305 bitmap_clear_bit (tab->partition_in_use, p);
306 BITMAP_FREE (tab->kill_list[p]);
311 /* Add a dependency between the def of ssa VERSION and VAR. If VAR is
312 replaceable by an expression, add a dependence each of the elements of the
313 expression. These are contained in the new_replaceable list. TAB is the
314 expression table. */
316 static void
317 add_dependence (temp_expr_table_p tab, int version, tree var)
319 int i;
320 bitmap_iterator bi;
321 unsigned x;
323 i = SSA_NAME_VERSION (var);
324 if (version_to_be_replaced_p (tab, i))
326 if (!bitmap_empty_p (tab->new_replaceable_dependencies))
328 /* Version will now be killed by a write to any partition the
329 substituted expression would have been killed by. */
330 EXECUTE_IF_SET_IN_BITMAP (tab->new_replaceable_dependencies, 0, x, bi)
331 add_to_partition_kill_list (tab, x, version);
333 /* Rather than set partition_dependencies and in_use lists bit by
334 bit, simply OR in the new_replaceable_dependencies bits. */
335 if (!tab->partition_dependencies[version])
336 tab->partition_dependencies[version] =
337 BITMAP_ALLOC (&ter_bitmap_obstack);
338 bitmap_ior_into (tab->partition_dependencies[version],
339 tab->new_replaceable_dependencies);
340 bitmap_ior_into (tab->partition_in_use,
341 tab->new_replaceable_dependencies);
342 /* It is only necessary to add these once. */
343 bitmap_clear (tab->new_replaceable_dependencies);
346 else
348 i = var_to_partition (tab->map, var);
349 gcc_checking_assert (i != NO_PARTITION);
350 gcc_checking_assert (tab->num_in_part[i] != 0);
351 /* Only dependencies on ssa_names which are coalesced with something need
352 to be tracked. Partitions with containing only a single SSA_NAME
353 *cannot* have their value changed. */
354 if (tab->num_in_part[i] > 1)
356 add_to_partition_kill_list (tab, i, version);
357 make_dependent_on_partition (tab, version, i);
363 /* Return TRUE if expression STMT is suitable for replacement.
364 TER is true if is_replaceable_p is called from within TER, false
365 when used from within stmt_is_replaceable_p, i.e. EXPAND_INITIALIZER
366 expansion. The differences are that with !TER some tests are skipped
367 to make it more aggressive (doesn't require the same bb, or for -O0
368 same locus and same BLOCK), on the other side never considers memory
369 loads as replaceable, because those don't ever lead into constant
370 expressions. */
372 static inline bool
373 is_replaceable_p (gimple stmt, bool ter)
375 use_operand_p use_p;
376 tree def;
377 gimple use_stmt;
378 location_t locus1, locus2;
379 tree block1, block2;
381 /* Only consider modify stmts. */
382 if (!is_gimple_assign (stmt))
383 return false;
385 /* If the statement may throw an exception, it cannot be replaced. */
386 if (stmt_could_throw_p (stmt))
387 return false;
389 /* Punt if there is more than 1 def. */
390 def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF);
391 if (!def)
392 return false;
394 /* Only consider definitions which have a single use. */
395 if (!single_imm_use (def, &use_p, &use_stmt))
396 return false;
398 /* If the use isn't in this block, it wont be replaced either. */
399 if (ter && gimple_bb (use_stmt) != gimple_bb (stmt))
400 return false;
402 locus1 = gimple_location (stmt);
403 block1 = gimple_block (stmt);
405 if (gimple_code (use_stmt) == GIMPLE_PHI)
407 locus2 = 0;
408 block2 = NULL_TREE;
410 else
412 locus2 = gimple_location (use_stmt);
413 block2 = gimple_block (use_stmt);
416 if (!optimize
417 && ter
418 && ((locus1 && locus1 != locus2) || (block1 && block1 != block2)))
419 return false;
421 /* Used in this block, but at the TOP of the block, not the end. */
422 if (gimple_code (use_stmt) == GIMPLE_PHI)
423 return false;
425 /* There must be no VDEFs. */
426 if (gimple_vdef (stmt))
427 return false;
429 /* Without alias info we can't move around loads. */
430 if ((!optimize || !ter)
431 && gimple_assign_single_p (stmt)
432 && !is_gimple_val (gimple_assign_rhs1 (stmt)))
433 return false;
435 /* Float expressions must go through memory if float-store is on. */
436 if (flag_float_store
437 && FLOAT_TYPE_P (gimple_expr_type (stmt)))
438 return false;
440 /* An assignment with a register variable on the RHS is not
441 replaceable. */
442 if (gimple_assign_rhs_code (stmt) == VAR_DECL
443 && DECL_HARD_REGISTER (gimple_assign_rhs1 (stmt)))
444 return false;
446 /* No function calls can be replaced. */
447 if (is_gimple_call (stmt))
448 return false;
450 /* Leave any stmt with volatile operands alone as well. */
451 if (gimple_has_volatile_ops (stmt))
452 return false;
454 return true;
458 /* Variant of is_replaceable_p test for use in EXPAND_INITIALIZER
459 expansion. */
461 bool
462 stmt_is_replaceable_p (gimple stmt)
464 return is_replaceable_p (stmt, false);
468 /* This function will remove the expression for VERSION from replacement
469 consideration in table TAB. If FREE_EXPR is true, then remove the
470 expression from consideration as well by freeing the decl uid bitmap. */
472 static void
473 finished_with_expr (temp_expr_table_p tab, int version, bool free_expr)
475 unsigned i;
476 bitmap_iterator bi;
478 /* Remove this expression from its dependent lists. The partition dependence
479 list is retained and transferred later to whomever uses this version. */
480 if (tab->partition_dependencies[version])
482 EXECUTE_IF_SET_IN_BITMAP (tab->partition_dependencies[version], 0, i, bi)
483 remove_from_partition_kill_list (tab, i, version);
484 BITMAP_FREE (tab->partition_dependencies[version]);
486 if (free_expr)
487 BITMAP_FREE (tab->expr_decl_uids[version]);
491 /* Create an expression entry for a replaceable expression. */
493 static void
494 process_replaceable (temp_expr_table_p tab, gimple stmt, int call_cnt)
496 tree var, def, basevar;
497 int version;
498 ssa_op_iter iter;
499 bitmap def_vars, use_vars;
501 gcc_checking_assert (is_replaceable_p (stmt, true));
503 def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF);
504 version = SSA_NAME_VERSION (def);
505 def_vars = BITMAP_ALLOC (&ter_bitmap_obstack);
507 basevar = SSA_NAME_VAR (def);
508 if (basevar)
509 bitmap_set_bit (def_vars, DECL_UID (basevar));
511 /* Add this expression to the dependency list for each use partition. */
512 FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE)
514 int var_version = SSA_NAME_VERSION (var);
516 use_vars = tab->expr_decl_uids[var_version];
517 add_dependence (tab, version, var);
518 if (use_vars)
520 bitmap_ior_into (def_vars, use_vars);
521 BITMAP_FREE (tab->expr_decl_uids[var_version]);
523 else if (SSA_NAME_VAR (var))
524 bitmap_set_bit (def_vars, DECL_UID (SSA_NAME_VAR (var)));
526 tab->expr_decl_uids[version] = def_vars;
528 /* If there are VUSES, add a dependence on virtual defs. */
529 if (gimple_vuse (stmt))
531 make_dependent_on_partition (tab, version, VIRTUAL_PARTITION (tab));
532 add_to_partition_kill_list (tab, VIRTUAL_PARTITION (tab), version);
535 tab->call_cnt[version] = call_cnt;
539 /* This function removes any expression in TAB which is dependent on PARTITION
540 from consideration, making it not replaceable. */
542 static inline void
543 kill_expr (temp_expr_table_p tab, int partition)
545 unsigned version;
547 /* Mark every active expr dependent on this var as not replaceable.
548 finished_with_expr can modify the bitmap, so we can't execute over it. */
549 while (tab->kill_list[partition])
551 version = bitmap_first_set_bit (tab->kill_list[partition]);
552 finished_with_expr (tab, version, true);
555 gcc_checking_assert (!tab->kill_list[partition]);
559 /* This function kills all expressions in TAB which are dependent on virtual
560 partitions. */
562 static inline void
563 kill_virtual_exprs (temp_expr_table_p tab)
565 kill_expr (tab, VIRTUAL_PARTITION (tab));
569 /* Mark the expression associated with VAR as replaceable, and enter
570 the defining stmt into the partition_dependencies table TAB. If
571 MORE_REPLACING is true, accumulate the pending partition dependencies. */
573 static void
574 mark_replaceable (temp_expr_table_p tab, tree var, bool more_replacing)
576 int version = SSA_NAME_VERSION (var);
578 /* Move the dependence list to the pending listpending. */
579 if (more_replacing && tab->partition_dependencies[version])
580 bitmap_ior_into (tab->new_replaceable_dependencies,
581 tab->partition_dependencies[version]);
583 finished_with_expr (tab, version, !more_replacing);
585 /* Set the replaceable expression.
586 The bitmap for this "escapes" from this file so it's allocated
587 on the default obstack. */
588 if (!tab->replaceable_expressions)
589 tab->replaceable_expressions = BITMAP_ALLOC (NULL);
590 bitmap_set_bit (tab->replaceable_expressions, version);
594 /* This function processes basic block BB, and looks for variables which can
595 be replaced by their expressions. Results are stored in the table TAB. */
597 static void
598 find_replaceable_in_bb (temp_expr_table_p tab, basic_block bb)
600 gimple_stmt_iterator bsi;
601 gimple stmt;
602 tree def, use, fndecl;
603 int partition;
604 var_map map = tab->map;
605 ssa_op_iter iter;
606 bool stmt_replaceable;
607 int cur_call_cnt = 0;
609 for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
611 stmt = gsi_stmt (bsi);
613 if (is_gimple_debug (stmt))
614 continue;
616 stmt_replaceable = is_replaceable_p (stmt, true);
618 /* Determine if this stmt finishes an existing expression. */
619 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
621 unsigned ver = SSA_NAME_VERSION (use);
623 /* If this use is a potential replacement variable, process it. */
624 if (tab->expr_decl_uids[ver])
626 bool same_root_var = false;
627 ssa_op_iter iter2;
628 bitmap vars = tab->expr_decl_uids[ver];
630 /* See if the root variables are the same. If they are, we
631 do not want to do the replacement to avoid problems with
632 code size, see PR tree-optimization/17549. */
633 if (!bitmap_empty_p (vars))
634 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter2, SSA_OP_DEF)
636 if (SSA_NAME_VAR (def)
637 && bitmap_bit_p (vars, DECL_UID (SSA_NAME_VAR (def))))
639 same_root_var = true;
640 break;
644 /* If the stmt does a memory store and the replacement
645 is a load aliasing it avoid creating overlapping
646 assignments which we cannot expand correctly. */
647 if (gimple_vdef (stmt)
648 && gimple_assign_single_p (stmt))
650 gimple def_stmt = SSA_NAME_DEF_STMT (use);
651 while (is_gimple_assign (def_stmt)
652 && gimple_assign_rhs_code (def_stmt) == SSA_NAME)
653 def_stmt
654 = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (def_stmt));
655 if (gimple_vuse (def_stmt)
656 && gimple_assign_single_p (def_stmt)
657 && refs_may_alias_p (gimple_assign_lhs (stmt),
658 gimple_assign_rhs1 (def_stmt)))
659 same_root_var = true;
662 /* Mark expression as replaceable unless stmt is volatile, or the
663 def variable has the same root variable as something in the
664 substitution list, or the def and use span a call such that
665 we'll expand lifetimes across a call. */
666 if (gimple_has_volatile_ops (stmt) || same_root_var
667 || (tab->call_cnt[ver] != cur_call_cnt
668 && SINGLE_SSA_USE_OPERAND (SSA_NAME_DEF_STMT (use), SSA_OP_USE)
669 == NULL_USE_OPERAND_P))
670 finished_with_expr (tab, ver, true);
671 else
672 mark_replaceable (tab, use, stmt_replaceable);
676 /* Next, see if this stmt kills off an active expression. */
677 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
679 partition = var_to_partition (map, def);
680 if (partition != NO_PARTITION && tab->kill_list[partition])
681 kill_expr (tab, partition);
684 /* Increment counter if this is a non BUILT_IN call. We allow
685 replacement over BUILT_IN calls since many will expand to inline
686 insns instead of a true call. */
687 if (is_gimple_call (stmt)
688 && !((fndecl = gimple_call_fndecl (stmt))
689 && DECL_BUILT_IN (fndecl)))
690 cur_call_cnt++;
692 /* Now see if we are creating a new expression or not. */
693 if (stmt_replaceable)
694 process_replaceable (tab, stmt, cur_call_cnt);
696 /* Free any unused dependency lists. */
697 bitmap_clear (tab->new_replaceable_dependencies);
699 /* A V_{MAY,MUST}_DEF kills any expression using a virtual operand,
700 including the current stmt. */
701 if (gimple_vdef (stmt))
702 kill_virtual_exprs (tab);
707 /* This function is the driver routine for replacement of temporary expressions
708 in the SSA->normal phase, operating on MAP. If there are replaceable
709 expressions, a table is returned which maps SSA versions to the
710 expressions they should be replaced with. A NULL_TREE indicates no
711 replacement should take place. If there are no replacements at all,
712 NULL is returned by the function, otherwise an expression vector indexed
713 by SSA_NAME version numbers. */
715 bitmap
716 find_replaceable_exprs (var_map map)
718 basic_block bb;
719 temp_expr_table_p table;
720 bitmap ret;
722 bitmap_obstack_initialize (&ter_bitmap_obstack);
723 table = new_temp_expr_table (map);
724 FOR_EACH_BB (bb)
726 find_replaceable_in_bb (table, bb);
727 gcc_checking_assert (bitmap_empty_p (table->partition_in_use));
729 ret = free_temp_expr_table (table);
730 bitmap_obstack_release (&ter_bitmap_obstack);
731 return ret;
734 /* Dump TER expression table EXPR to file F. */
736 void
737 dump_replaceable_exprs (FILE *f, bitmap expr)
739 tree var;
740 unsigned x;
742 fprintf (f, "\nReplacing Expressions\n");
743 for (x = 0; x < num_ssa_names; x++)
744 if (bitmap_bit_p (expr, x))
746 var = ssa_name (x);
747 print_generic_expr (f, var, TDF_SLIM);
748 fprintf (f, " replace with --> ");
749 print_gimple_stmt (f, SSA_NAME_DEF_STMT (var), 0, TDF_SLIM);
750 fprintf (f, "\n");
752 fprintf (f, "\n");
756 #ifdef ENABLE_CHECKING
757 /* Dump the status of the various tables in the expression table. This is used
758 exclusively to debug TER. F is the place to send debug info and T is the
759 table being debugged. */
761 DEBUG_FUNCTION void
762 debug_ter (FILE *f, temp_expr_table_p t)
764 unsigned x, y;
765 bitmap_iterator bi;
767 fprintf (f, "\nDumping current state of TER\n virtual partition = %d\n",
768 VIRTUAL_PARTITION (t));
769 if (t->replaceable_expressions)
770 dump_replaceable_exprs (f, t->replaceable_expressions);
771 fprintf (f, "Currently tracking the following expressions:\n");
773 for (x = 1; x < num_ssa_names; x++)
774 if (t->expr_decl_uids[x])
776 print_generic_expr (f, ssa_name (x), TDF_SLIM);
777 fprintf (f, " dep-parts : ");
778 if (t->partition_dependencies[x]
779 && !bitmap_empty_p (t->partition_dependencies[x]))
781 EXECUTE_IF_SET_IN_BITMAP (t->partition_dependencies[x], 0, y, bi)
782 fprintf (f, "P%d ",y);
784 fprintf (f, " basedecls: ");
785 EXECUTE_IF_SET_IN_BITMAP (t->expr_decl_uids[x], 0, y, bi)
786 fprintf (f, "%d ",y);
787 fprintf (f, " call_cnt : %d",t->call_cnt[x]);
788 fprintf (f, "\n");
791 bitmap_print (f, t->partition_in_use, "Partitions in use ",
792 "\npartition KILL lists:\n");
794 for (x = 0; x <= num_var_partitions (t->map); x++)
795 if (t->kill_list[x])
797 fprintf (f, "Partition %d : ", x);
798 EXECUTE_IF_SET_IN_BITMAP (t->kill_list[x], 0, y, bi)
799 fprintf (f, "_%d ",y);
802 fprintf (f, "\n----------\n");
804 #endif