1 /* SSA Dominator optimizations for trees
2 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
5 This file is part of GCC.
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 2, or (at your option)
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.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
24 #include "coretypes.h"
31 #include "basic-block.h"
36 #include "diagnostic.h"
38 #include "tree-dump.h"
39 #include "tree-flow.h"
42 #include "tree-pass.h"
43 #include "tree-ssa-propagate.h"
44 #include "langhooks.h"
47 /* This file implements optimizations on the dominator tree. */
50 /* Structure for recording edge equivalences as well as any pending
51 edge redirections during the dominator optimizer.
53 Computing and storing the edge equivalences instead of creating
54 them on-demand can save significant amounts of time, particularly
55 for pathological cases involving switch statements.
57 These structures live for a single iteration of the dominator
58 optimizer in the edge's AUX field. At the end of an iteration we
59 free each of these structures and update the AUX field to point
60 to any requested redirection target (the code for updating the
61 CFG and SSA graph for edge redirection expects redirection edge
62 targets to be in the AUX field for each edge. */
66 /* If this edge creates a simple equivalence, the LHS and RHS of
67 the equivalence will be stored here. */
71 /* Traversing an edge may also indicate one or more particular conditions
72 are true or false. The number of recorded conditions can vary, but
73 can be determined by the condition's code. So we have an array
74 and its maximum index rather than use a varray. */
75 tree *cond_equivalences;
76 unsigned int max_cond_equivalences;
78 /* If we can thread this edge this field records the new target. */
79 edge redirection_target;
83 /* Hash table with expressions made available during the renaming process.
84 When an assignment of the form X_i = EXPR is found, the statement is
85 stored in this table. If the same expression EXPR is later found on the
86 RHS of another statement, it is replaced with X_i (thus performing
87 global redundancy elimination). Similarly as we pass through conditionals
88 we record the conditional itself as having either a true or false value
90 static htab_t avail_exprs;
92 /* Stack of available expressions in AVAIL_EXPRs. Each block pushes any
93 expressions it enters into the hash table along with a marker entry
94 (null). When we finish processing the block, we pop off entries and
95 remove the expressions from the global hash table until we hit the
97 static VEC(tree,heap) *avail_exprs_stack;
99 /* Stack of statements we need to rescan during finalization for newly
102 Statement rescanning must occur after the current block's available
103 expressions are removed from AVAIL_EXPRS. Else we may change the
104 hash code for an expression and be unable to find/remove it from
106 static VEC(tree,heap) *stmts_to_rescan;
108 /* Structure for entries in the expression hash table.
110 This requires more memory for the hash table entries, but allows us
111 to avoid creating silly tree nodes and annotations for conditionals,
112 eliminates 2 global hash tables and two block local varrays.
114 It also allows us to reduce the number of hash table lookups we
115 have to perform in lookup_avail_expr and finally it allows us to
116 significantly reduce the number of calls into the hashing routine
121 /* The value (lhs) of this expression. */
124 /* The expression (rhs) we want to record. */
127 /* The stmt pointer if this element corresponds to a statement. */
130 /* The hash value for RHS/ann. */
134 /* Stack of dest,src pairs that need to be restored during finalization.
136 A NULL entry is used to mark the end of pairs which need to be
137 restored during finalization of this block. */
138 static VEC(tree,heap) *const_and_copies_stack;
140 /* Bitmap of SSA_NAMEs known to have a nonzero value, even if we do not
141 know their exact value. */
142 static bitmap nonzero_vars;
144 /* Bitmap of blocks that are scheduled to be threaded through. This
145 is used to communicate with thread_through_blocks. */
146 static bitmap threaded_blocks;
148 /* Stack of SSA_NAMEs which need their NONZERO_VARS property cleared
149 when the current block is finalized.
151 A NULL entry is used to mark the end of names needing their
152 entry in NONZERO_VARS cleared during finalization of this block. */
153 static VEC(tree,heap) *nonzero_vars_stack;
155 /* Track whether or not we have changed the control flow graph. */
156 static bool cfg_altered;
158 /* Bitmap of blocks that have had EH statements cleaned. We should
159 remove their dead edges eventually. */
160 static bitmap need_eh_cleanup;
162 /* Statistics for dominator optimizations. */
166 long num_exprs_considered;
173 static struct opt_stats_d opt_stats;
175 /* Value range propagation record. Each time we encounter a conditional
176 of the form SSA_NAME COND CONST we create a new vrp_element to record
177 how the condition affects the possible values SSA_NAME may have.
179 Each record contains the condition tested (COND), and the range of
180 values the variable may legitimately have if COND is true. Note the
181 range of values may be a smaller range than COND specifies if we have
182 recorded other ranges for this variable. Each record also contains the
183 block in which the range was recorded for invalidation purposes.
185 Note that the current known range is computed lazily. This allows us
186 to avoid the overhead of computing ranges which are never queried.
188 When we encounter a conditional, we look for records which constrain
189 the SSA_NAME used in the condition. In some cases those records allow
190 us to determine the condition's result at compile time. In other cases
191 they may allow us to simplify the condition.
193 We also use value ranges to do things like transform signed div/mod
194 operations into unsigned div/mod or to simplify ABS_EXPRs.
196 Simple experiments have shown these optimizations to not be all that
197 useful on switch statements (much to my surprise). So switch statement
198 optimizations are not performed.
200 Note carefully we do not propagate information through each statement
201 in the block. i.e., if we know variable X has a value defined of
202 [0, 25] and we encounter Y = X + 1, we do not track a value range
203 for Y (which would be [1, 26] if we cared). Similarly we do not
204 constrain values as we encounter narrowing typecasts, etc. */
208 /* The highest and lowest values the variable in COND may contain when
209 COND is true. Note this may not necessarily be the same values
210 tested by COND if the same variable was used in earlier conditionals.
212 Note this is computed lazily and thus can be NULL indicating that
213 the values have not been computed yet. */
217 /* The actual conditional we recorded. This is needed since we compute
221 /* The basic block where this record was created. We use this to determine
222 when to remove records. */
226 /* A hash table holding value range records (VRP_ELEMENTs) for a given
227 SSA_NAME. We used to use a varray indexed by SSA_NAME_VERSION, but
228 that gets awful wasteful, particularly since the density objects
229 with useful information is very low. */
230 static htab_t vrp_data;
232 typedef struct vrp_element *vrp_element_p;
234 DEF_VEC_P(vrp_element_p);
235 DEF_VEC_ALLOC_P(vrp_element_p,heap);
237 /* An entry in the VRP_DATA hash table. We record the variable and a
238 varray of VRP_ELEMENT records associated with that variable. */
242 VEC(vrp_element_p,heap) *records;
245 /* Array of variables which have their values constrained by operations
246 in this basic block. We use this during finalization to know
247 which variables need their VRP data updated. */
249 /* Stack of SSA_NAMEs which had their values constrained by operations
250 in this basic block. During finalization of this block we use this
251 list to determine which variables need their VRP data updated.
253 A NULL entry marks the end of the SSA_NAMEs associated with this block. */
254 static VEC(tree,heap) *vrp_variables_stack;
262 /* Local functions. */
263 static void optimize_stmt (struct dom_walk_data *,
265 block_stmt_iterator);
266 static tree lookup_avail_expr (tree, bool);
267 static hashval_t vrp_hash (const void *);
268 static int vrp_eq (const void *, const void *);
269 static hashval_t avail_expr_hash (const void *);
270 static hashval_t real_avail_expr_hash (const void *);
271 static int avail_expr_eq (const void *, const void *);
272 static void htab_statistics (FILE *, htab_t);
273 static void record_cond (tree, tree);
274 static void record_const_or_copy (tree, tree);
275 static void record_equality (tree, tree);
276 static tree simplify_cond_and_lookup_avail_expr (tree, stmt_ann_t, int);
277 static tree find_equivalent_equality_comparison (tree);
278 static void record_range (tree, basic_block);
279 static bool extract_range_from_cond (tree, tree *, tree *, int *);
280 static void record_equivalences_from_phis (basic_block);
281 static void record_equivalences_from_incoming_edge (basic_block);
282 static bool eliminate_redundant_computations (tree, stmt_ann_t);
283 static void record_equivalences_from_stmt (tree, int, stmt_ann_t);
284 static void thread_across_edge (struct dom_walk_data *, edge);
285 static void dom_opt_finalize_block (struct dom_walk_data *, basic_block);
286 static void dom_opt_initialize_block (struct dom_walk_data *, basic_block);
287 static void propagate_to_outgoing_edges (struct dom_walk_data *, basic_block);
288 static void remove_local_expressions_from_table (void);
289 static void restore_vars_to_original_value (void);
290 static edge single_incoming_edge_ignoring_loop_edges (basic_block);
291 static void restore_nonzero_vars_to_original_value (void);
292 static inline bool unsafe_associative_fp_binop (tree);
295 /* Local version of fold that doesn't introduce cruft. */
302 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that
303 may have been added by fold, and "useless" type conversions that might
304 now be apparent due to propagation. */
305 STRIP_USELESS_TYPE_CONVERSION (t);
310 /* Allocate an EDGE_INFO for edge E and attach it to E.
311 Return the new EDGE_INFO structure. */
313 static struct edge_info *
314 allocate_edge_info (edge e)
316 struct edge_info *edge_info;
318 edge_info = XCNEW (struct edge_info);
324 /* Free all EDGE_INFO structures associated with edges in the CFG.
325 If a particular edge can be threaded, copy the redirection
326 target from the EDGE_INFO structure into the edge's AUX field
327 as required by code to update the CFG and SSA graph for
331 free_all_edge_infos (void)
339 FOR_EACH_EDGE (e, ei, bb->preds)
341 struct edge_info *edge_info = (struct edge_info *) e->aux;
345 e->aux = edge_info->redirection_target;
346 if (edge_info->cond_equivalences)
347 free (edge_info->cond_equivalences);
354 /* Free an instance of vrp_hash_elt. */
357 vrp_free (void *data)
359 struct vrp_hash_elt *elt = (struct vrp_hash_elt *) data;
360 struct VEC(vrp_element_p,heap) **vrp_elt = &elt->records;
362 VEC_free (vrp_element_p, heap, *vrp_elt);
366 /* Jump threading, redundancy elimination and const/copy propagation.
368 This pass may expose new symbols that need to be renamed into SSA. For
369 every new symbol exposed, its corresponding bit will be set in
373 tree_ssa_dominator_optimize (void)
375 struct dom_walk_data walk_data;
377 struct loops loops_info;
379 memset (&opt_stats, 0, sizeof (opt_stats));
381 /* Create our hash tables. */
382 avail_exprs = htab_create (1024, real_avail_expr_hash, avail_expr_eq, free);
383 vrp_data = htab_create (ceil_log2 (num_ssa_names), vrp_hash, vrp_eq,
385 avail_exprs_stack = VEC_alloc (tree, heap, 20);
386 const_and_copies_stack = VEC_alloc (tree, heap, 20);
387 nonzero_vars_stack = VEC_alloc (tree, heap, 20);
388 vrp_variables_stack = VEC_alloc (tree, heap, 20);
389 stmts_to_rescan = VEC_alloc (tree, heap, 20);
390 nonzero_vars = BITMAP_ALLOC (NULL);
391 threaded_blocks = BITMAP_ALLOC (NULL);
392 need_eh_cleanup = BITMAP_ALLOC (NULL);
394 /* Setup callbacks for the generic dominator tree walker. */
395 walk_data.walk_stmts_backward = false;
396 walk_data.dom_direction = CDI_DOMINATORS;
397 walk_data.initialize_block_local_data = NULL;
398 walk_data.before_dom_children_before_stmts = dom_opt_initialize_block;
399 walk_data.before_dom_children_walk_stmts = optimize_stmt;
400 walk_data.before_dom_children_after_stmts = propagate_to_outgoing_edges;
401 walk_data.after_dom_children_before_stmts = NULL;
402 walk_data.after_dom_children_walk_stmts = NULL;
403 walk_data.after_dom_children_after_stmts = dom_opt_finalize_block;
404 /* Right now we only attach a dummy COND_EXPR to the global data pointer.
405 When we attach more stuff we'll need to fill this out with a real
407 walk_data.global_data = NULL;
408 walk_data.block_local_data_size = 0;
409 walk_data.interesting_blocks = NULL;
411 /* Now initialize the dominator walker. */
412 init_walk_dominator_tree (&walk_data);
414 calculate_dominance_info (CDI_DOMINATORS);
416 /* We need to know which edges exit loops so that we can
417 aggressively thread through loop headers to an exit
419 flow_loops_find (&loops_info);
420 mark_loop_exit_edges (&loops_info);
421 flow_loops_free (&loops_info);
423 /* Clean up the CFG so that any forwarder blocks created by loop
424 canonicalization are removed. */
426 calculate_dominance_info (CDI_DOMINATORS);
428 /* If we prove certain blocks are unreachable, then we want to
429 repeat the dominator optimization process as PHI nodes may
430 have turned into copies which allows better propagation of
431 values. So we repeat until we do not identify any new unreachable
435 /* Optimize the dominator tree. */
438 /* We need accurate information regarding back edges in the CFG
439 for jump threading. */
440 mark_dfs_back_edges ();
442 /* Recursively walk the dominator tree optimizing statements. */
443 walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
446 block_stmt_iterator bsi;
450 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
452 update_stmt_if_modified (bsi_stmt (bsi));
457 /* If we exposed any new variables, go ahead and put them into
458 SSA form now, before we handle jump threading. This simplifies
459 interactions between rewriting of _DECL nodes into SSA form
460 and rewriting SSA_NAME nodes into SSA form after block
461 duplication and CFG manipulation. */
462 update_ssa (TODO_update_ssa);
464 free_all_edge_infos ();
466 /* Thread jumps, creating duplicate blocks as needed. */
467 cfg_altered |= thread_through_all_blocks (threaded_blocks);
469 /* Removal of statements may make some EH edges dead. Purge
470 such edges from the CFG as needed. */
471 if (!bitmap_empty_p (need_eh_cleanup))
473 cfg_altered |= tree_purge_all_dead_eh_edges (need_eh_cleanup);
474 bitmap_zero (need_eh_cleanup);
478 free_dominance_info (CDI_DOMINATORS);
480 /* Only iterate if we threaded jumps AND the CFG cleanup did
481 something interesting. Other cases generate far fewer
482 optimization opportunities and thus are not worth another
483 full DOM iteration. */
484 cfg_altered &= cleanup_tree_cfg ();
486 if (rediscover_loops_after_threading)
488 /* Rerun basic loop analysis to discover any newly
489 created loops and update the set of exit edges. */
490 rediscover_loops_after_threading = false;
491 flow_loops_find (&loops_info);
492 mark_loop_exit_edges (&loops_info);
493 flow_loops_free (&loops_info);
495 /* Remove any forwarder blocks inserted by loop
496 header canonicalization. */
500 calculate_dominance_info (CDI_DOMINATORS);
502 update_ssa (TODO_update_ssa);
504 /* Reinitialize the various tables. */
505 bitmap_clear (nonzero_vars);
506 bitmap_clear (threaded_blocks);
507 htab_empty (avail_exprs);
508 htab_empty (vrp_data);
510 /* Finally, remove everything except invariants in SSA_NAME_VALUE.
512 This must be done before we iterate as we might have a
513 reference to an SSA_NAME which was removed by the call to
516 Long term we will be able to let everything in SSA_NAME_VALUE
517 persist. However, for now, we know this is the safe thing to do. */
518 for (i = 0; i < num_ssa_names; i++)
520 tree name = ssa_name (i);
526 value = SSA_NAME_VALUE (name);
527 if (value && !is_gimple_min_invariant (value))
528 SSA_NAME_VALUE (name) = NULL;
531 opt_stats.num_iterations++;
533 while (optimize > 1 && cfg_altered);
535 /* Debugging dumps. */
536 if (dump_file && (dump_flags & TDF_STATS))
537 dump_dominator_optimization_stats (dump_file);
539 /* We emptied the hash table earlier, now delete it completely. */
540 htab_delete (avail_exprs);
541 htab_delete (vrp_data);
543 /* It is not necessary to clear CURRDEFS, REDIRECTION_EDGES, VRP_DATA,
544 CONST_AND_COPIES, and NONZERO_VARS as they all get cleared at the bottom
545 of the do-while loop above. */
547 /* And finalize the dominator walker. */
548 fini_walk_dominator_tree (&walk_data);
550 /* Free nonzero_vars. */
551 BITMAP_FREE (nonzero_vars);
552 BITMAP_FREE (threaded_blocks);
553 BITMAP_FREE (need_eh_cleanup);
555 VEC_free (tree, heap, avail_exprs_stack);
556 VEC_free (tree, heap, const_and_copies_stack);
557 VEC_free (tree, heap, nonzero_vars_stack);
558 VEC_free (tree, heap, vrp_variables_stack);
559 VEC_free (tree, heap, stmts_to_rescan);
563 gate_dominator (void)
565 return flag_tree_dom != 0;
568 struct tree_opt_pass pass_dominator =
571 gate_dominator, /* gate */
572 tree_ssa_dominator_optimize, /* execute */
575 0, /* static_pass_number */
576 TV_TREE_SSA_DOMINATOR_OPTS, /* tv_id */
577 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
578 0, /* properties_provided */
579 0, /* properties_destroyed */
580 0, /* todo_flags_start */
583 | TODO_verify_ssa, /* todo_flags_finish */
588 /* Given a stmt CONDSTMT containing a COND_EXPR, canonicalize the
589 COND_EXPR into a canonical form. */
592 canonicalize_comparison (tree condstmt)
594 tree cond = COND_EXPR_COND (condstmt);
597 enum tree_code code = TREE_CODE (cond);
599 if (!COMPARISON_CLASS_P (cond))
602 op0 = TREE_OPERAND (cond, 0);
603 op1 = TREE_OPERAND (cond, 1);
605 /* If it would be profitable to swap the operands, then do so to
606 canonicalize the statement, enabling better optimization.
608 By placing canonicalization of such expressions here we
609 transparently keep statements in canonical form, even
610 when the statement is modified. */
611 if (tree_swap_operands_p (op0, op1, false))
613 /* For relationals we need to swap the operands
614 and change the code. */
620 TREE_SET_CODE (cond, swap_tree_comparison (code));
621 swap_tree_operands (condstmt,
622 &TREE_OPERAND (cond, 0),
623 &TREE_OPERAND (cond, 1));
624 /* If one operand was in the operand cache, but the other is
625 not, because it is a constant, this is a case that the
626 internal updating code of swap_tree_operands can't handle
628 if (TREE_CODE_CLASS (TREE_CODE (op0))
629 != TREE_CODE_CLASS (TREE_CODE (op1)))
630 update_stmt (condstmt);
634 /* We are exiting E->src, see if E->dest ends with a conditional
635 jump which has a known value when reached via E.
637 Special care is necessary if E is a back edge in the CFG as we
638 will have already recorded equivalences for E->dest into our
639 various tables, including the result of the conditional at
640 the end of E->dest. Threading opportunities are severely
641 limited in that case to avoid short-circuiting the loop
644 Note it is quite common for the first block inside a loop to
645 end with a conditional which is either always true or always
646 false when reached via the loop backedge. Thus we do not want
647 to blindly disable threading across a loop backedge. */
650 thread_across_edge (struct dom_walk_data *walk_data, edge e)
652 block_stmt_iterator bsi;
659 /* If E->dest does not end with a conditional, then there is
661 bsi = bsi_last (e->dest);
664 || (TREE_CODE (bsi_stmt (bsi)) != COND_EXPR
665 && TREE_CODE (bsi_stmt (bsi)) != GOTO_EXPR
666 && TREE_CODE (bsi_stmt (bsi)) != SWITCH_EXPR))
669 /* The basic idea here is to use whatever knowledge we have
670 from our dominator walk to simplify statements in E->dest,
671 with the ultimate goal being to simplify the conditional
672 at the end of E->dest.
674 Note that we must undo any changes we make to the underlying
675 statements as the simplifications we are making are control
676 flow sensitive (ie, the simplifications are valid when we
677 traverse E, but may not be valid on other paths to E->dest. */
679 /* Each PHI creates a temporary equivalence, record them. Again
680 these are context sensitive equivalences and will be removed
682 for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
684 tree src = PHI_ARG_DEF_FROM_EDGE (phi, e);
685 tree dst = PHI_RESULT (phi);
687 /* Do not include virtual PHIs in our statement count as
688 they never generate code. */
689 if (is_gimple_reg (dst))
692 /* If the desired argument is not the same as this PHI's result
693 and it is set by a PHI in E->dest, then we can not thread
696 && TREE_CODE (src) == SSA_NAME
697 && TREE_CODE (SSA_NAME_DEF_STMT (src)) == PHI_NODE
698 && bb_for_stmt (SSA_NAME_DEF_STMT (src)) == e->dest)
701 record_const_or_copy (dst, src);
704 /* Try to simplify each statement in E->dest, ultimately leading to
705 a simplification of the COND_EXPR at the end of E->dest.
707 We might consider marking just those statements which ultimately
708 feed the COND_EXPR. It's not clear if the overhead of bookkeeping
709 would be recovered by trying to simplify fewer statements.
711 If we are able to simplify a statement into the form
712 SSA_NAME = (SSA_NAME | gimple invariant), then we can record
713 a context sensitive equivalency which may help us simplify
714 later statements in E->dest.
716 Failure to simplify into the form above merely means that the
717 statement provides no equivalences to help simplify later
718 statements. This does not prevent threading through E->dest. */
719 max_stmt_count = PARAM_VALUE (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS);
720 for (bsi = bsi_start (e->dest); ! bsi_end_p (bsi); bsi_next (&bsi))
722 tree cached_lhs = NULL;
724 stmt = bsi_stmt (bsi);
726 /* Ignore empty statements and labels. */
727 if (IS_EMPTY_STMT (stmt) || TREE_CODE (stmt) == LABEL_EXPR)
730 /* If duplicating this block is going to cause too much code
731 expansion, then do not thread through this block. */
733 if (stmt_count > max_stmt_count)
736 /* Safely handle threading across loop backedges. This is
737 over conservative, but still allows us to capture the
738 majority of the cases where we can thread across a loop
740 if ((e->flags & EDGE_DFS_BACK) != 0
741 && TREE_CODE (stmt) != COND_EXPR
742 && TREE_CODE (stmt) != SWITCH_EXPR)
745 /* If the statement has volatile operands, then we assume we
746 can not thread through this block. This is overly
747 conservative in some ways. */
748 if (TREE_CODE (stmt) == ASM_EXPR && ASM_VOLATILE_P (stmt))
751 /* If this is not a MODIFY_EXPR which sets an SSA_NAME to a new
752 value, then do not try to simplify this statement as it will
753 not simplify in any way that is helpful for jump threading. */
754 if (TREE_CODE (stmt) != MODIFY_EXPR
755 || TREE_CODE (TREE_OPERAND (stmt, 0)) != SSA_NAME)
758 /* At this point we have a statement which assigns an RHS to an
759 SSA_VAR on the LHS. We want to try and simplify this statement
760 to expose more context sensitive equivalences which in turn may
761 allow us to simplify the condition at the end of the loop. */
762 if (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME)
763 cached_lhs = TREE_OPERAND (stmt, 1);
766 /* Copy the operands. */
767 tree *copy, pre_fold_expr;
770 unsigned int num, i = 0;
772 num = NUM_SSA_OPERANDS (stmt, (SSA_OP_USE | SSA_OP_VUSE));
773 copy = XCNEWVEC (tree, num);
775 /* Make a copy of the uses & vuses into USES_COPY, then cprop into
777 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
780 tree use = USE_FROM_PTR (use_p);
783 if (TREE_CODE (use) == SSA_NAME)
784 tmp = SSA_NAME_VALUE (use);
785 if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
786 SET_USE (use_p, tmp);
789 /* Try to fold/lookup the new expression. Inserting the
790 expression into the hash table is unlikely to help
791 Sadly, we have to handle conditional assignments specially
792 here, because fold expects all the operands of an expression
793 to be folded before the expression itself is folded, but we
794 can't just substitute the folded condition here. */
795 if (TREE_CODE (TREE_OPERAND (stmt, 1)) == COND_EXPR)
797 tree cond = COND_EXPR_COND (TREE_OPERAND (stmt, 1));
799 if (cond == boolean_true_node)
800 pre_fold_expr = COND_EXPR_THEN (TREE_OPERAND (stmt, 1));
801 else if (cond == boolean_false_node)
802 pre_fold_expr = COND_EXPR_ELSE (TREE_OPERAND (stmt, 1));
804 pre_fold_expr = TREE_OPERAND (stmt, 1);
807 pre_fold_expr = TREE_OPERAND (stmt, 1);
811 cached_lhs = fold (pre_fold_expr);
812 if (TREE_CODE (cached_lhs) != SSA_NAME
813 && !is_gimple_min_invariant (cached_lhs))
814 cached_lhs = lookup_avail_expr (stmt, false);
817 /* Restore the statement's original uses/defs. */
819 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
820 SET_USE (use_p, copy[i++]);
825 /* Record the context sensitive equivalence if we were able
826 to simplify this statement. */
828 && (TREE_CODE (cached_lhs) == SSA_NAME
829 || is_gimple_min_invariant (cached_lhs)))
830 record_const_or_copy (TREE_OPERAND (stmt, 0), cached_lhs);
833 /* If we stopped at a COND_EXPR or SWITCH_EXPR, see if we know which arm
836 && (TREE_CODE (stmt) == COND_EXPR
837 || TREE_CODE (stmt) == GOTO_EXPR
838 || TREE_CODE (stmt) == SWITCH_EXPR))
840 tree cond, cached_lhs;
842 /* Now temporarily cprop the operands and try to find the resulting
843 expression in the hash tables. */
844 if (TREE_CODE (stmt) == COND_EXPR)
846 canonicalize_comparison (stmt);
847 cond = COND_EXPR_COND (stmt);
849 else if (TREE_CODE (stmt) == GOTO_EXPR)
850 cond = GOTO_DESTINATION (stmt);
852 cond = SWITCH_COND (stmt);
854 if (COMPARISON_CLASS_P (cond))
856 tree dummy_cond, op0, op1;
857 enum tree_code cond_code;
859 op0 = TREE_OPERAND (cond, 0);
860 op1 = TREE_OPERAND (cond, 1);
861 cond_code = TREE_CODE (cond);
863 /* Get the current value of both operands. */
864 if (TREE_CODE (op0) == SSA_NAME)
866 tree tmp = SSA_NAME_VALUE (op0);
867 if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
871 if (TREE_CODE (op1) == SSA_NAME)
873 tree tmp = SSA_NAME_VALUE (op1);
874 if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
878 /* Stuff the operator and operands into our dummy conditional
879 expression, creating the dummy conditional if necessary. */
880 dummy_cond = (tree) walk_data->global_data;
883 dummy_cond = build2 (cond_code, boolean_type_node, op0, op1);
884 dummy_cond = build3 (COND_EXPR, void_type_node,
885 dummy_cond, NULL_TREE, NULL_TREE);
886 walk_data->global_data = dummy_cond;
890 TREE_SET_CODE (COND_EXPR_COND (dummy_cond), cond_code);
891 TREE_OPERAND (COND_EXPR_COND (dummy_cond), 0) = op0;
892 TREE_OPERAND (COND_EXPR_COND (dummy_cond), 1) = op1;
895 /* We absolutely do not care about any type conversions
896 we only care about a zero/nonzero value. */
897 cached_lhs = fold (COND_EXPR_COND (dummy_cond));
898 while (TREE_CODE (cached_lhs) == NOP_EXPR
899 || TREE_CODE (cached_lhs) == CONVERT_EXPR
900 || TREE_CODE (cached_lhs) == NON_LVALUE_EXPR)
901 cached_lhs = TREE_OPERAND (cached_lhs, 0);
903 if (! is_gimple_min_invariant (cached_lhs))
905 cached_lhs = lookup_avail_expr (dummy_cond, false);
906 if (!cached_lhs || ! is_gimple_min_invariant (cached_lhs))
907 cached_lhs = simplify_cond_and_lookup_avail_expr (dummy_cond,
912 /* We can have conditionals which just test the state of a
913 variable rather than use a relational operator. These are
914 simpler to handle. */
915 else if (TREE_CODE (cond) == SSA_NAME)
918 cached_lhs = SSA_NAME_VALUE (cached_lhs);
919 if (cached_lhs && ! is_gimple_min_invariant (cached_lhs))
923 cached_lhs = lookup_avail_expr (stmt, false);
927 edge taken_edge = find_taken_edge (e->dest, cached_lhs);
928 basic_block dest = (taken_edge ? taken_edge->dest : NULL);
933 /* If we have a known destination for the conditional, then
934 we can perform this optimization, which saves at least one
935 conditional jump each time it applies since we get to
936 bypass the conditional at our original destination. */
939 struct edge_info *edge_info;
942 edge_info = (struct edge_info *) e->aux;
944 edge_info = allocate_edge_info (e);
945 edge_info->redirection_target = taken_edge;
946 bitmap_set_bit (threaded_blocks, e->dest->index);
953 /* Initialize local stacks for this optimizer and record equivalences
954 upon entry to BB. Equivalences can come from the edge traversed to
955 reach BB or they may come from PHI nodes at the start of BB. */
958 dom_opt_initialize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
961 if (dump_file && (dump_flags & TDF_DETAILS))
962 fprintf (dump_file, "\n\nOptimizing block #%d\n\n", bb->index);
964 /* Push a marker on the stacks of local information so that we know how
965 far to unwind when we finalize this block. */
966 VEC_safe_push (tree, heap, avail_exprs_stack, NULL_TREE);
967 VEC_safe_push (tree, heap, const_and_copies_stack, NULL_TREE);
968 VEC_safe_push (tree, heap, nonzero_vars_stack, NULL_TREE);
969 VEC_safe_push (tree, heap, vrp_variables_stack, NULL_TREE);
971 record_equivalences_from_incoming_edge (bb);
973 /* PHI nodes can create equivalences too. */
974 record_equivalences_from_phis (bb);
977 /* Given an expression EXPR (a relational expression or a statement),
978 initialize the hash table element pointed to by ELEMENT. */
981 initialize_hash_element (tree expr, tree lhs, struct expr_hash_elt *element)
983 /* Hash table elements may be based on conditional expressions or statements.
985 For the former case, we have no annotation and we want to hash the
986 conditional expression. In the latter case we have an annotation and
987 we want to record the expression the statement evaluates. */
988 if (COMPARISON_CLASS_P (expr) || TREE_CODE (expr) == TRUTH_NOT_EXPR)
990 element->stmt = NULL;
993 else if (TREE_CODE (expr) == COND_EXPR)
995 element->stmt = expr;
996 element->rhs = COND_EXPR_COND (expr);
998 else if (TREE_CODE (expr) == SWITCH_EXPR)
1000 element->stmt = expr;
1001 element->rhs = SWITCH_COND (expr);
1003 else if (TREE_CODE (expr) == RETURN_EXPR && TREE_OPERAND (expr, 0))
1005 element->stmt = expr;
1006 element->rhs = TREE_OPERAND (TREE_OPERAND (expr, 0), 1);
1008 else if (TREE_CODE (expr) == GOTO_EXPR)
1010 element->stmt = expr;
1011 element->rhs = GOTO_DESTINATION (expr);
1015 element->stmt = expr;
1016 element->rhs = TREE_OPERAND (expr, 1);
1020 element->hash = avail_expr_hash (element);
1023 /* Remove all the expressions in LOCALS from TABLE, stopping when there are
1024 LIMIT entries left in LOCALs. */
1027 remove_local_expressions_from_table (void)
1029 /* Remove all the expressions made available in this block. */
1030 while (VEC_length (tree, avail_exprs_stack) > 0)
1032 struct expr_hash_elt element;
1033 tree expr = VEC_pop (tree, avail_exprs_stack);
1035 if (expr == NULL_TREE)
1038 initialize_hash_element (expr, NULL, &element);
1039 htab_remove_elt_with_hash (avail_exprs, &element, element.hash);
1043 /* Use the SSA_NAMES in LOCALS to restore TABLE to its original
1044 state, stopping when there are LIMIT entries left in LOCALs. */
1047 restore_nonzero_vars_to_original_value (void)
1049 while (VEC_length (tree, nonzero_vars_stack) > 0)
1051 tree name = VEC_pop (tree, nonzero_vars_stack);
1056 bitmap_clear_bit (nonzero_vars, SSA_NAME_VERSION (name));
1060 /* Use the source/dest pairs in CONST_AND_COPIES_STACK to restore
1061 CONST_AND_COPIES to its original state, stopping when we hit a
1065 restore_vars_to_original_value (void)
1067 while (VEC_length (tree, const_and_copies_stack) > 0)
1069 tree prev_value, dest;
1071 dest = VEC_pop (tree, const_and_copies_stack);
1076 prev_value = VEC_pop (tree, const_and_copies_stack);
1077 SSA_NAME_VALUE (dest) = prev_value;
1081 /* We have finished processing the dominator children of BB, perform
1082 any finalization actions in preparation for leaving this node in
1083 the dominator tree. */
1086 dom_opt_finalize_block (struct dom_walk_data *walk_data, basic_block bb)
1090 /* If we have an outgoing edge to a block with multiple incoming and
1091 outgoing edges, then we may be able to thread the edge. ie, we
1092 may be able to statically determine which of the outgoing edges
1093 will be traversed when the incoming edge from BB is traversed. */
1094 if (single_succ_p (bb)
1095 && (single_succ_edge (bb)->flags & EDGE_ABNORMAL) == 0
1096 && !single_pred_p (single_succ (bb))
1097 && !single_succ_p (single_succ (bb)))
1100 thread_across_edge (walk_data, single_succ_edge (bb));
1102 else if ((last = last_stmt (bb))
1103 && TREE_CODE (last) == COND_EXPR
1104 && (COMPARISON_CLASS_P (COND_EXPR_COND (last))
1105 || TREE_CODE (COND_EXPR_COND (last)) == SSA_NAME)
1106 && EDGE_COUNT (bb->succs) == 2
1107 && (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) == 0
1108 && (EDGE_SUCC (bb, 1)->flags & EDGE_ABNORMAL) == 0)
1110 edge true_edge, false_edge;
1112 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
1114 /* Only try to thread the edge if it reaches a target block with
1115 more than one predecessor and more than one successor. */
1116 if (!single_pred_p (true_edge->dest) && !single_succ_p (true_edge->dest))
1118 struct edge_info *edge_info;
1121 /* Push a marker onto the available expression stack so that we
1122 unwind any expressions related to the TRUE arm before processing
1123 the false arm below. */
1124 VEC_safe_push (tree, heap, avail_exprs_stack, NULL_TREE);
1125 VEC_safe_push (tree, heap, const_and_copies_stack, NULL_TREE);
1127 edge_info = (struct edge_info *) true_edge->aux;
1129 /* If we have info associated with this edge, record it into
1130 our equivalency tables. */
1133 tree *cond_equivalences = edge_info->cond_equivalences;
1134 tree lhs = edge_info->lhs;
1135 tree rhs = edge_info->rhs;
1137 /* If we have a simple NAME = VALUE equivalency record it. */
1138 if (lhs && TREE_CODE (lhs) == SSA_NAME)
1139 record_const_or_copy (lhs, rhs);
1141 /* If we have 0 = COND or 1 = COND equivalences, record them
1142 into our expression hash tables. */
1143 if (cond_equivalences)
1144 for (i = 0; i < edge_info->max_cond_equivalences; i += 2)
1146 tree expr = cond_equivalences[i];
1147 tree value = cond_equivalences[i + 1];
1149 record_cond (expr, value);
1153 /* Now thread the edge. */
1154 thread_across_edge (walk_data, true_edge);
1156 /* And restore the various tables to their state before
1157 we threaded this edge. */
1158 remove_local_expressions_from_table ();
1159 restore_vars_to_original_value ();
1162 /* Similarly for the ELSE arm. */
1163 if (!single_pred_p (false_edge->dest) && !single_succ_p (false_edge->dest))
1165 struct edge_info *edge_info;
1168 edge_info = (struct edge_info *) false_edge->aux;
1170 /* If we have info associated with this edge, record it into
1171 our equivalency tables. */
1174 tree *cond_equivalences = edge_info->cond_equivalences;
1175 tree lhs = edge_info->lhs;
1176 tree rhs = edge_info->rhs;
1178 /* If we have a simple NAME = VALUE equivalency record it. */
1179 if (lhs && TREE_CODE (lhs) == SSA_NAME)
1180 record_const_or_copy (lhs, rhs);
1182 /* If we have 0 = COND or 1 = COND equivalences, record them
1183 into our expression hash tables. */
1184 if (cond_equivalences)
1185 for (i = 0; i < edge_info->max_cond_equivalences; i += 2)
1187 tree expr = cond_equivalences[i];
1188 tree value = cond_equivalences[i + 1];
1190 record_cond (expr, value);
1194 thread_across_edge (walk_data, false_edge);
1196 /* No need to remove local expressions from our tables
1197 or restore vars to their original value as that will
1198 be done immediately below. */
1202 remove_local_expressions_from_table ();
1203 restore_nonzero_vars_to_original_value ();
1204 restore_vars_to_original_value ();
1206 /* Remove VRP records associated with this basic block. They are no
1209 To be efficient, we note which variables have had their values
1210 constrained in this block. So walk over each variable in the
1211 VRP_VARIABLEs array. */
1212 while (VEC_length (tree, vrp_variables_stack) > 0)
1214 tree var = VEC_pop (tree, vrp_variables_stack);
1215 struct vrp_hash_elt vrp_hash_elt, *vrp_hash_elt_p;
1218 /* Each variable has a stack of value range records. We want to
1219 invalidate those associated with our basic block. So we walk
1220 the array backwards popping off records associated with our
1221 block. Once we hit a record not associated with our block
1223 VEC(vrp_element_p,heap) **var_vrp_records;
1228 vrp_hash_elt.var = var;
1229 vrp_hash_elt.records = NULL;
1231 slot = htab_find_slot (vrp_data, &vrp_hash_elt, NO_INSERT);
1233 vrp_hash_elt_p = (struct vrp_hash_elt *) *slot;
1234 var_vrp_records = &vrp_hash_elt_p->records;
1236 while (VEC_length (vrp_element_p, *var_vrp_records) > 0)
1238 struct vrp_element *element
1239 = VEC_last (vrp_element_p, *var_vrp_records);
1241 if (element->bb != bb)
1244 VEC_pop (vrp_element_p, *var_vrp_records);
1248 /* If we queued any statements to rescan in this block, then
1249 go ahead and rescan them now. */
1250 while (VEC_length (tree, stmts_to_rescan) > 0)
1252 tree stmt = VEC_last (tree, stmts_to_rescan);
1253 basic_block stmt_bb = bb_for_stmt (stmt);
1258 VEC_pop (tree, stmts_to_rescan);
1259 mark_new_vars_to_rename (stmt);
1263 /* PHI nodes can create equivalences too.
1265 Ignoring any alternatives which are the same as the result, if
1266 all the alternatives are equal, then the PHI node creates an
1269 Additionally, if all the PHI alternatives are known to have a nonzero
1270 value, then the result of this PHI is known to have a nonzero value,
1271 even if we do not know its exact value. */
1274 record_equivalences_from_phis (basic_block bb)
1278 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
1280 tree lhs = PHI_RESULT (phi);
1284 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
1286 tree t = PHI_ARG_DEF (phi, i);
1288 /* Ignore alternatives which are the same as our LHS. Since
1289 LHS is a PHI_RESULT, it is known to be a SSA_NAME, so we
1290 can simply compare pointers. */
1294 /* If we have not processed an alternative yet, then set
1295 RHS to this alternative. */
1298 /* If we have processed an alternative (stored in RHS), then
1299 see if it is equal to this one. If it isn't, then stop
1301 else if (! operand_equal_for_phi_arg_p (rhs, t))
1305 /* If we had no interesting alternatives, then all the RHS alternatives
1306 must have been the same as LHS. */
1310 /* If we managed to iterate through each PHI alternative without
1311 breaking out of the loop, then we have a PHI which may create
1312 a useful equivalence. We do not need to record unwind data for
1313 this, since this is a true assignment and not an equivalence
1314 inferred from a comparison. All uses of this ssa name are dominated
1315 by this assignment, so unwinding just costs time and space. */
1316 if (i == PHI_NUM_ARGS (phi)
1317 && may_propagate_copy (lhs, rhs))
1318 SSA_NAME_VALUE (lhs) = rhs;
1320 /* Now see if we know anything about the nonzero property for the
1321 result of this PHI. */
1322 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
1324 if (!PHI_ARG_NONZERO (phi, i))
1328 if (i == PHI_NUM_ARGS (phi))
1329 bitmap_set_bit (nonzero_vars, SSA_NAME_VERSION (PHI_RESULT (phi)));
1333 /* Ignoring loop backedges, if BB has precisely one incoming edge then
1334 return that edge. Otherwise return NULL. */
1336 single_incoming_edge_ignoring_loop_edges (basic_block bb)
1342 FOR_EACH_EDGE (e, ei, bb->preds)
1344 /* A loop back edge can be identified by the destination of
1345 the edge dominating the source of the edge. */
1346 if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest))
1349 /* If we have already seen a non-loop edge, then we must have
1350 multiple incoming non-loop edges and thus we return NULL. */
1354 /* This is the first non-loop incoming edge we have found. Record
1362 /* Record any equivalences created by the incoming edge to BB. If BB
1363 has more than one incoming edge, then no equivalence is created. */
1366 record_equivalences_from_incoming_edge (basic_block bb)
1370 struct edge_info *edge_info;
1372 /* If our parent block ended with a control statement, then we may be
1373 able to record some equivalences based on which outgoing edge from
1374 the parent was followed. */
1375 parent = get_immediate_dominator (CDI_DOMINATORS, bb);
1377 e = single_incoming_edge_ignoring_loop_edges (bb);
1379 /* If we had a single incoming edge from our parent block, then enter
1380 any data associated with the edge into our tables. */
1381 if (e && e->src == parent)
1385 edge_info = (struct edge_info *) e->aux;
1389 tree lhs = edge_info->lhs;
1390 tree rhs = edge_info->rhs;
1391 tree *cond_equivalences = edge_info->cond_equivalences;
1394 record_equality (lhs, rhs);
1396 if (cond_equivalences)
1398 bool recorded_range = false;
1399 for (i = 0; i < edge_info->max_cond_equivalences; i += 2)
1401 tree expr = cond_equivalences[i];
1402 tree value = cond_equivalences[i + 1];
1404 record_cond (expr, value);
1406 /* For the first true equivalence, record range
1407 information. We only do this for the first
1408 true equivalence as it should dominate any
1409 later true equivalences. */
1410 if (! recorded_range
1411 && COMPARISON_CLASS_P (expr)
1412 && value == boolean_true_node
1413 && TREE_CONSTANT (TREE_OPERAND (expr, 1)))
1415 record_range (expr, bb);
1416 recorded_range = true;
1424 /* Dump SSA statistics on FILE. */
1427 dump_dominator_optimization_stats (FILE *file)
1431 fprintf (file, "Total number of statements: %6ld\n\n",
1432 opt_stats.num_stmts);
1433 fprintf (file, "Exprs considered for dominator optimizations: %6ld\n",
1434 opt_stats.num_exprs_considered);
1436 n_exprs = opt_stats.num_exprs_considered;
1440 fprintf (file, " Redundant expressions eliminated: %6ld (%.0f%%)\n",
1441 opt_stats.num_re, PERCENT (opt_stats.num_re,
1443 fprintf (file, " Constants propagated: %6ld\n",
1444 opt_stats.num_const_prop);
1445 fprintf (file, " Copies propagated: %6ld\n",
1446 opt_stats.num_copy_prop);
1448 fprintf (file, "\nTotal number of DOM iterations: %6ld\n",
1449 opt_stats.num_iterations);
1451 fprintf (file, "\nHash table statistics:\n");
1453 fprintf (file, " avail_exprs: ");
1454 htab_statistics (file, avail_exprs);
1458 /* Dump SSA statistics on stderr. */
1461 debug_dominator_optimization_stats (void)
1463 dump_dominator_optimization_stats (stderr);
1467 /* Dump statistics for the hash table HTAB. */
1470 htab_statistics (FILE *file, htab_t htab)
1472 fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n",
1473 (long) htab_size (htab),
1474 (long) htab_elements (htab),
1475 htab_collisions (htab));
1478 /* Record the fact that VAR has a nonzero value, though we may not know
1479 its exact value. Note that if VAR is already known to have a nonzero
1480 value, then we do nothing. */
1483 record_var_is_nonzero (tree var)
1485 int indx = SSA_NAME_VERSION (var);
1487 if (bitmap_bit_p (nonzero_vars, indx))
1490 /* Mark it in the global table. */
1491 bitmap_set_bit (nonzero_vars, indx);
1493 /* Record this SSA_NAME so that we can reset the global table
1494 when we leave this block. */
1495 VEC_safe_push (tree, heap, nonzero_vars_stack, var);
1498 /* Enter a statement into the true/false expression hash table indicating
1499 that the condition COND has the value VALUE. */
1502 record_cond (tree cond, tree value)
1504 struct expr_hash_elt *element = XCNEW (struct expr_hash_elt);
1507 initialize_hash_element (cond, value, element);
1509 slot = htab_find_slot_with_hash (avail_exprs, (void *)element,
1510 element->hash, INSERT);
1513 *slot = (void *) element;
1514 VEC_safe_push (tree, heap, avail_exprs_stack, cond);
1520 /* Build a new conditional using NEW_CODE, OP0 and OP1 and store
1521 the new conditional into *p, then store a boolean_true_node
1525 build_and_record_new_cond (enum tree_code new_code, tree op0, tree op1, tree *p)
1527 *p = build2 (new_code, boolean_type_node, op0, op1);
1529 *p = boolean_true_node;
1532 /* Record that COND is true and INVERTED is false into the edge information
1533 structure. Also record that any conditions dominated by COND are true
1536 For example, if a < b is true, then a <= b must also be true. */
1539 record_conditions (struct edge_info *edge_info, tree cond, tree inverted)
1543 if (!COMPARISON_CLASS_P (cond))
1546 op0 = TREE_OPERAND (cond, 0);
1547 op1 = TREE_OPERAND (cond, 1);
1549 switch (TREE_CODE (cond))
1553 edge_info->max_cond_equivalences = 12;
1554 edge_info->cond_equivalences = XNEWVEC (tree, 12);
1555 build_and_record_new_cond ((TREE_CODE (cond) == LT_EXPR
1556 ? LE_EXPR : GE_EXPR),
1557 op0, op1, &edge_info->cond_equivalences[4]);
1558 build_and_record_new_cond (ORDERED_EXPR, op0, op1,
1559 &edge_info->cond_equivalences[6]);
1560 build_and_record_new_cond (NE_EXPR, op0, op1,
1561 &edge_info->cond_equivalences[8]);
1562 build_and_record_new_cond (LTGT_EXPR, op0, op1,
1563 &edge_info->cond_equivalences[10]);
1568 edge_info->max_cond_equivalences = 6;
1569 edge_info->cond_equivalences = XNEWVEC (tree, 6);
1570 build_and_record_new_cond (ORDERED_EXPR, op0, op1,
1571 &edge_info->cond_equivalences[4]);
1575 edge_info->max_cond_equivalences = 10;
1576 edge_info->cond_equivalences = XNEWVEC (tree, 10);
1577 build_and_record_new_cond (ORDERED_EXPR, op0, op1,
1578 &edge_info->cond_equivalences[4]);
1579 build_and_record_new_cond (LE_EXPR, op0, op1,
1580 &edge_info->cond_equivalences[6]);
1581 build_and_record_new_cond (GE_EXPR, op0, op1,
1582 &edge_info->cond_equivalences[8]);
1585 case UNORDERED_EXPR:
1586 edge_info->max_cond_equivalences = 16;
1587 edge_info->cond_equivalences = XNEWVEC (tree, 16);
1588 build_and_record_new_cond (NE_EXPR, op0, op1,
1589 &edge_info->cond_equivalences[4]);
1590 build_and_record_new_cond (UNLE_EXPR, op0, op1,
1591 &edge_info->cond_equivalences[6]);
1592 build_and_record_new_cond (UNGE_EXPR, op0, op1,
1593 &edge_info->cond_equivalences[8]);
1594 build_and_record_new_cond (UNEQ_EXPR, op0, op1,
1595 &edge_info->cond_equivalences[10]);
1596 build_and_record_new_cond (UNLT_EXPR, op0, op1,
1597 &edge_info->cond_equivalences[12]);
1598 build_and_record_new_cond (UNGT_EXPR, op0, op1,
1599 &edge_info->cond_equivalences[14]);
1604 edge_info->max_cond_equivalences = 8;
1605 edge_info->cond_equivalences = XNEWVEC (tree, 8);
1606 build_and_record_new_cond ((TREE_CODE (cond) == UNLT_EXPR
1607 ? UNLE_EXPR : UNGE_EXPR),
1608 op0, op1, &edge_info->cond_equivalences[4]);
1609 build_and_record_new_cond (NE_EXPR, op0, op1,
1610 &edge_info->cond_equivalences[6]);
1614 edge_info->max_cond_equivalences = 8;
1615 edge_info->cond_equivalences = XNEWVEC (tree, 8);
1616 build_and_record_new_cond (UNLE_EXPR, op0, op1,
1617 &edge_info->cond_equivalences[4]);
1618 build_and_record_new_cond (UNGE_EXPR, op0, op1,
1619 &edge_info->cond_equivalences[6]);
1623 edge_info->max_cond_equivalences = 8;
1624 edge_info->cond_equivalences = XNEWVEC (tree, 8);
1625 build_and_record_new_cond (NE_EXPR, op0, op1,
1626 &edge_info->cond_equivalences[4]);
1627 build_and_record_new_cond (ORDERED_EXPR, op0, op1,
1628 &edge_info->cond_equivalences[6]);
1632 edge_info->max_cond_equivalences = 4;
1633 edge_info->cond_equivalences = XNEWVEC (tree, 4);
1637 /* Now store the original true and false conditions into the first
1639 edge_info->cond_equivalences[0] = cond;
1640 edge_info->cond_equivalences[1] = boolean_true_node;
1641 edge_info->cond_equivalences[2] = inverted;
1642 edge_info->cond_equivalences[3] = boolean_false_node;
1645 /* A helper function for record_const_or_copy and record_equality.
1646 Do the work of recording the value and undo info. */
1649 record_const_or_copy_1 (tree x, tree y, tree prev_x)
1651 SSA_NAME_VALUE (x) = y;
1653 VEC_reserve (tree, heap, const_and_copies_stack, 2);
1654 VEC_quick_push (tree, const_and_copies_stack, prev_x);
1655 VEC_quick_push (tree, const_and_copies_stack, x);
1659 /* Return the loop depth of the basic block of the defining statement of X.
1660 This number should not be treated as absolutely correct because the loop
1661 information may not be completely up-to-date when dom runs. However, it
1662 will be relatively correct, and as more passes are taught to keep loop info
1663 up to date, the result will become more and more accurate. */
1666 loop_depth_of_name (tree x)
1671 /* If it's not an SSA_NAME, we have no clue where the definition is. */
1672 if (TREE_CODE (x) != SSA_NAME)
1675 /* Otherwise return the loop depth of the defining statement's bb.
1676 Note that there may not actually be a bb for this statement, if the
1677 ssa_name is live on entry. */
1678 defstmt = SSA_NAME_DEF_STMT (x);
1679 defbb = bb_for_stmt (defstmt);
1683 return defbb->loop_depth;
1687 /* Record that X is equal to Y in const_and_copies. Record undo
1688 information in the block-local vector. */
1691 record_const_or_copy (tree x, tree y)
1693 tree prev_x = SSA_NAME_VALUE (x);
1695 if (TREE_CODE (y) == SSA_NAME)
1697 tree tmp = SSA_NAME_VALUE (y);
1702 record_const_or_copy_1 (x, y, prev_x);
1705 /* Similarly, but assume that X and Y are the two operands of an EQ_EXPR.
1706 This constrains the cases in which we may treat this as assignment. */
1709 record_equality (tree x, tree y)
1711 tree prev_x = NULL, prev_y = NULL;
1713 if (TREE_CODE (x) == SSA_NAME)
1714 prev_x = SSA_NAME_VALUE (x);
1715 if (TREE_CODE (y) == SSA_NAME)
1716 prev_y = SSA_NAME_VALUE (y);
1718 /* If one of the previous values is invariant, or invariant in more loops
1719 (by depth), then use that.
1720 Otherwise it doesn't matter which value we choose, just so
1721 long as we canonicalize on one value. */
1722 if (TREE_INVARIANT (y))
1724 else if (TREE_INVARIANT (x) || (loop_depth_of_name (x) <= loop_depth_of_name (y)))
1725 prev_x = x, x = y, y = prev_x, prev_x = prev_y;
1726 else if (prev_x && TREE_INVARIANT (prev_x))
1727 x = y, y = prev_x, prev_x = prev_y;
1728 else if (prev_y && TREE_CODE (prev_y) != VALUE_HANDLE)
1731 /* After the swapping, we must have one SSA_NAME. */
1732 if (TREE_CODE (x) != SSA_NAME)
1735 /* For IEEE, -0.0 == 0.0, so we don't necessarily know the sign of a
1736 variable compared against zero. If we're honoring signed zeros,
1737 then we cannot record this value unless we know that the value is
1739 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (x)))
1740 && (TREE_CODE (y) != REAL_CST
1741 || REAL_VALUES_EQUAL (dconst0, TREE_REAL_CST (y))))
1744 record_const_or_copy_1 (x, y, prev_x);
1747 /* Return true, if it is ok to do folding of an associative expression.
1748 EXP is the tree for the associative expression. */
1751 unsafe_associative_fp_binop (tree exp)
1753 enum tree_code code = TREE_CODE (exp);
1754 return !(!flag_unsafe_math_optimizations
1755 && (code == MULT_EXPR || code == PLUS_EXPR
1756 || code == MINUS_EXPR)
1757 && FLOAT_TYPE_P (TREE_TYPE (exp)));
1760 /* Returns true when STMT is a simple iv increment. It detects the
1761 following situation:
1763 i_1 = phi (..., i_2)
1764 i_2 = i_1 +/- ... */
1767 simple_iv_increment_p (tree stmt)
1769 tree lhs, rhs, preinc, phi;
1772 if (TREE_CODE (stmt) != MODIFY_EXPR)
1775 lhs = TREE_OPERAND (stmt, 0);
1776 if (TREE_CODE (lhs) != SSA_NAME)
1779 rhs = TREE_OPERAND (stmt, 1);
1781 if (TREE_CODE (rhs) != PLUS_EXPR
1782 && TREE_CODE (rhs) != MINUS_EXPR)
1785 preinc = TREE_OPERAND (rhs, 0);
1786 if (TREE_CODE (preinc) != SSA_NAME)
1789 phi = SSA_NAME_DEF_STMT (preinc);
1790 if (TREE_CODE (phi) != PHI_NODE)
1793 for (i = 0; i < (unsigned) PHI_NUM_ARGS (phi); i++)
1794 if (PHI_ARG_DEF (phi, i) == lhs)
1800 /* COND is a condition of the form:
1802 x == const or x != const
1804 Look back to x's defining statement and see if x is defined as
1808 If const is unchanged if we convert it to type, then we can build
1809 the equivalent expression:
1812 y == const or y != const
1814 Which may allow further optimizations.
1816 Return the equivalent comparison or NULL if no such equivalent comparison
1820 find_equivalent_equality_comparison (tree cond)
1822 tree op0 = TREE_OPERAND (cond, 0);
1823 tree op1 = TREE_OPERAND (cond, 1);
1824 tree def_stmt = SSA_NAME_DEF_STMT (op0);
1826 /* OP0 might have been a parameter, so first make sure it
1827 was defined by a MODIFY_EXPR. */
1828 if (def_stmt && TREE_CODE (def_stmt) == MODIFY_EXPR)
1830 tree def_rhs = TREE_OPERAND (def_stmt, 1);
1833 /* If either operand to the comparison is a pointer to
1834 a function, then we can not apply this optimization
1835 as some targets require function pointers to be
1836 canonicalized and in this case this optimization would
1837 eliminate a necessary canonicalization. */
1838 if ((POINTER_TYPE_P (TREE_TYPE (op0))
1839 && TREE_CODE (TREE_TYPE (TREE_TYPE (op0))) == FUNCTION_TYPE)
1840 || (POINTER_TYPE_P (TREE_TYPE (op1))
1841 && TREE_CODE (TREE_TYPE (TREE_TYPE (op1))) == FUNCTION_TYPE))
1844 /* Now make sure the RHS of the MODIFY_EXPR is a typecast. */
1845 if ((TREE_CODE (def_rhs) == NOP_EXPR
1846 || TREE_CODE (def_rhs) == CONVERT_EXPR)
1847 && TREE_CODE (TREE_OPERAND (def_rhs, 0)) == SSA_NAME)
1849 tree def_rhs_inner = TREE_OPERAND (def_rhs, 0);
1850 tree def_rhs_inner_type = TREE_TYPE (def_rhs_inner);
1853 if (TYPE_PRECISION (def_rhs_inner_type)
1854 > TYPE_PRECISION (TREE_TYPE (def_rhs)))
1857 /* If the inner type of the conversion is a pointer to
1858 a function, then we can not apply this optimization
1859 as some targets require function pointers to be
1860 canonicalized. This optimization would result in
1861 canonicalization of the pointer when it was not originally
1863 if (POINTER_TYPE_P (def_rhs_inner_type)
1864 && TREE_CODE (TREE_TYPE (def_rhs_inner_type)) == FUNCTION_TYPE)
1867 /* What we want to prove is that if we convert OP1 to
1868 the type of the object inside the NOP_EXPR that the
1869 result is still equivalent to SRC.
1871 If that is true, the build and return new equivalent
1872 condition which uses the source of the typecast and the
1873 new constant (which has only changed its type). */
1874 new = build1 (TREE_CODE (def_rhs), def_rhs_inner_type, op1);
1875 new = local_fold (new);
1876 if (is_gimple_val (new) && tree_int_cst_equal (new, op1))
1877 return build2 (TREE_CODE (cond), TREE_TYPE (cond),
1878 def_rhs_inner, new);
1884 /* STMT is a COND_EXPR for which we could not trivially determine its
1885 result. This routine attempts to find equivalent forms of the
1886 condition which we may be able to optimize better. It also
1887 uses simple value range propagation to optimize conditionals. */
1890 simplify_cond_and_lookup_avail_expr (tree stmt,
1894 tree cond = COND_EXPR_COND (stmt);
1896 if (COMPARISON_CLASS_P (cond))
1898 tree op0 = TREE_OPERAND (cond, 0);
1899 tree op1 = TREE_OPERAND (cond, 1);
1901 if (TREE_CODE (op0) == SSA_NAME && is_gimple_min_invariant (op1))
1904 tree low, high, cond_low, cond_high;
1905 int lowequal, highequal, swapped, no_overlap, subset, cond_inverted;
1906 VEC(vrp_element_p,heap) **vrp_records;
1907 struct vrp_element *element;
1908 struct vrp_hash_elt vrp_hash_elt, *vrp_hash_elt_p;
1911 /* First see if we have test of an SSA_NAME against a constant
1912 where the SSA_NAME is defined by an earlier typecast which
1913 is irrelevant when performing tests against the given
1915 if (TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1917 tree new_cond = find_equivalent_equality_comparison (cond);
1921 /* Update the statement to use the new equivalent
1923 COND_EXPR_COND (stmt) = new_cond;
1925 /* If this is not a real stmt, ann will be NULL and we
1926 avoid processing the operands. */
1928 mark_stmt_modified (stmt);
1930 /* Lookup the condition and return its known value if it
1932 new_cond = lookup_avail_expr (stmt, insert);
1936 /* The operands have changed, so update op0 and op1. */
1937 op0 = TREE_OPERAND (cond, 0);
1938 op1 = TREE_OPERAND (cond, 1);
1942 /* Consult the value range records for this variable (if they exist)
1943 to see if we can eliminate or simplify this conditional.
1945 Note two tests are necessary to determine no records exist.
1946 First we have to see if the virtual array exists, if it
1947 exists, then we have to check its active size.
1949 Also note the vast majority of conditionals are not testing
1950 a variable which has had its range constrained by an earlier
1951 conditional. So this filter avoids a lot of unnecessary work. */
1952 vrp_hash_elt.var = op0;
1953 vrp_hash_elt.records = NULL;
1954 slot = htab_find_slot (vrp_data, &vrp_hash_elt, NO_INSERT);
1958 vrp_hash_elt_p = (struct vrp_hash_elt *) *slot;
1959 vrp_records = &vrp_hash_elt_p->records;
1961 limit = VEC_length (vrp_element_p, *vrp_records);
1963 /* If we have no value range records for this variable, or we are
1964 unable to extract a range for this condition, then there is
1967 || ! extract_range_from_cond (cond, &cond_high,
1968 &cond_low, &cond_inverted))
1971 /* We really want to avoid unnecessary computations of range
1972 info. So all ranges are computed lazily; this avoids a
1973 lot of unnecessary work. i.e., we record the conditional,
1974 but do not process how it constrains the variable's
1975 potential values until we know that processing the condition
1978 However, we do not want to have to walk a potentially long
1979 list of ranges, nor do we want to compute a variable's
1980 range more than once for a given path.
1982 Luckily, each time we encounter a conditional that can not
1983 be otherwise optimized we will end up here and we will
1984 compute the necessary range information for the variable
1985 used in this condition.
1987 Thus you can conclude that there will never be more than one
1988 conditional associated with a variable which has not been
1989 processed. So we never need to merge more than one new
1990 conditional into the current range.
1992 These properties also help us avoid unnecessary work. */
1993 element = VEC_last (vrp_element_p, *vrp_records);
1995 if (element->high && element->low)
1997 /* The last element has been processed, so there is no range
1998 merging to do, we can simply use the high/low values
1999 recorded in the last element. */
2001 high = element->high;
2005 tree tmp_high, tmp_low;
2008 /* The last element has not been processed. Process it now.
2009 record_range should ensure for cond inverted is not set.
2010 This call can only fail if cond is x < min or x > max,
2011 which fold should have optimized into false.
2012 If that doesn't happen, just pretend all values are
2014 if (! extract_range_from_cond (element->cond, &tmp_high,
2018 gcc_assert (dummy == 0);
2020 /* If this is the only element, then no merging is necessary,
2021 the high/low values from extract_range_from_cond are all
2030 /* Get the high/low value from the previous element. */
2031 struct vrp_element *prev
2032 = VEC_index (vrp_element_p, *vrp_records, limit - 2);
2036 /* Merge in this element's range with the range from the
2039 The low value for the merged range is the maximum of
2040 the previous low value and the low value of this record.
2042 Similarly the high value for the merged range is the
2043 minimum of the previous high value and the high value of
2045 low = (low && tree_int_cst_compare (low, tmp_low) == 1
2047 high = (high && tree_int_cst_compare (high, tmp_high) == -1
2051 /* And record the computed range. */
2053 element->high = high;
2057 /* After we have constrained this variable's potential values,
2058 we try to determine the result of the given conditional.
2060 To simplify later tests, first determine if the current
2061 low value is the same low value as the conditional.
2062 Similarly for the current high value and the high value
2063 for the conditional. */
2064 lowequal = tree_int_cst_equal (low, cond_low);
2065 highequal = tree_int_cst_equal (high, cond_high);
2067 if (lowequal && highequal)
2068 return (cond_inverted ? boolean_false_node : boolean_true_node);
2070 /* To simplify the overlap/subset tests below we may want
2071 to swap the two ranges so that the larger of the two
2072 ranges occurs "first". */
2074 if (tree_int_cst_compare (low, cond_low) == 1
2076 && tree_int_cst_compare (cond_high, high) == 1))
2089 /* Now determine if there is no overlap in the ranges
2090 or if the second range is a subset of the first range. */
2091 no_overlap = tree_int_cst_lt (high, cond_low);
2092 subset = tree_int_cst_compare (cond_high, high) != 1;
2094 /* If there was no overlap in the ranges, then this conditional
2095 always has a false value (unless we had to invert this
2096 conditional, in which case it always has a true value). */
2098 return (cond_inverted ? boolean_true_node : boolean_false_node);
2100 /* If the current range is a subset of the condition's range,
2101 then this conditional always has a true value (unless we
2102 had to invert this conditional, in which case it always
2103 has a true value). */
2104 if (subset && swapped)
2105 return (cond_inverted ? boolean_false_node : boolean_true_node);
2107 /* We were unable to determine the result of the conditional.
2108 However, we may be able to simplify the conditional. First
2109 merge the ranges in the same manner as range merging above. */
2110 low = tree_int_cst_compare (low, cond_low) == 1 ? low : cond_low;
2111 high = tree_int_cst_compare (high, cond_high) == -1 ? high : cond_high;
2113 /* If the range has converged to a single point, then turn this
2114 into an equality comparison. */
2115 if (TREE_CODE (cond) != EQ_EXPR
2116 && TREE_CODE (cond) != NE_EXPR
2117 && tree_int_cst_equal (low, high))
2119 TREE_SET_CODE (cond, EQ_EXPR);
2120 TREE_OPERAND (cond, 1) = high;
2127 /* CONST_AND_COPIES is a table which maps an SSA_NAME to the current
2128 known value for that SSA_NAME (or NULL if no value is known).
2130 NONZERO_VARS is the set SSA_NAMES known to have a nonzero value,
2131 even if we don't know their precise value.
2133 Propagate values from CONST_AND_COPIES and NONZERO_VARS into the PHI
2134 nodes of the successors of BB. */
2137 cprop_into_successor_phis (basic_block bb, bitmap nonzero_vars)
2142 FOR_EACH_EDGE (e, ei, bb->succs)
2147 /* If this is an abnormal edge, then we do not want to copy propagate
2148 into the PHI alternative associated with this edge. */
2149 if (e->flags & EDGE_ABNORMAL)
2152 phi = phi_nodes (e->dest);
2157 for ( ; phi; phi = PHI_CHAIN (phi))
2160 use_operand_p orig_p;
2163 /* The alternative may be associated with a constant, so verify
2164 it is an SSA_NAME before doing anything with it. */
2165 orig_p = PHI_ARG_DEF_PTR (phi, indx);
2166 orig = USE_FROM_PTR (orig_p);
2167 if (TREE_CODE (orig) != SSA_NAME)
2170 /* If the alternative is known to have a nonzero value, record
2171 that fact in the PHI node itself for future use. */
2172 if (bitmap_bit_p (nonzero_vars, SSA_NAME_VERSION (orig)))
2173 PHI_ARG_NONZERO (phi, indx) = true;
2175 /* If we have *ORIG_P in our constant/copy table, then replace
2176 ORIG_P with its value in our constant/copy table. */
2177 new = SSA_NAME_VALUE (orig);
2180 && (TREE_CODE (new) == SSA_NAME
2181 || is_gimple_min_invariant (new))
2182 && may_propagate_copy (orig, new))
2183 propagate_value (orig_p, new);
2188 /* We have finished optimizing BB, record any information implied by
2189 taking a specific outgoing edge from BB. */
2192 record_edge_info (basic_block bb)
2194 block_stmt_iterator bsi = bsi_last (bb);
2195 struct edge_info *edge_info;
2197 if (! bsi_end_p (bsi))
2199 tree stmt = bsi_stmt (bsi);
2201 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
2203 tree cond = SWITCH_COND (stmt);
2205 if (TREE_CODE (cond) == SSA_NAME)
2207 tree labels = SWITCH_LABELS (stmt);
2208 int i, n_labels = TREE_VEC_LENGTH (labels);
2209 tree *info = XCNEWVEC (tree, last_basic_block);
2213 for (i = 0; i < n_labels; i++)
2215 tree label = TREE_VEC_ELT (labels, i);
2216 basic_block target_bb = label_to_block (CASE_LABEL (label));
2218 if (CASE_HIGH (label)
2219 || !CASE_LOW (label)
2220 || info[target_bb->index])
2221 info[target_bb->index] = error_mark_node;
2223 info[target_bb->index] = label;
2226 FOR_EACH_EDGE (e, ei, bb->succs)
2228 basic_block target_bb = e->dest;
2229 tree node = info[target_bb->index];
2231 if (node != NULL && node != error_mark_node)
2233 tree x = fold_convert (TREE_TYPE (cond), CASE_LOW (node));
2234 edge_info = allocate_edge_info (e);
2235 edge_info->lhs = cond;
2243 /* A COND_EXPR may create equivalences too. */
2244 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2246 tree cond = COND_EXPR_COND (stmt);
2250 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2252 /* If the conditional is a single variable 'X', record 'X = 1'
2253 for the true edge and 'X = 0' on the false edge. */
2254 if (SSA_VAR_P (cond))
2256 struct edge_info *edge_info;
2258 edge_info = allocate_edge_info (true_edge);
2259 edge_info->lhs = cond;
2260 edge_info->rhs = constant_boolean_node (1, TREE_TYPE (cond));
2262 edge_info = allocate_edge_info (false_edge);
2263 edge_info->lhs = cond;
2264 edge_info->rhs = constant_boolean_node (0, TREE_TYPE (cond));
2266 /* Equality tests may create one or two equivalences. */
2267 else if (COMPARISON_CLASS_P (cond))
2269 tree op0 = TREE_OPERAND (cond, 0);
2270 tree op1 = TREE_OPERAND (cond, 1);
2272 /* Special case comparing booleans against a constant as we
2273 know the value of OP0 on both arms of the branch. i.e., we
2274 can record an equivalence for OP0 rather than COND. */
2275 if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
2276 && TREE_CODE (op0) == SSA_NAME
2277 && TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE
2278 && is_gimple_min_invariant (op1))
2280 if (TREE_CODE (cond) == EQ_EXPR)
2282 edge_info = allocate_edge_info (true_edge);
2283 edge_info->lhs = op0;
2284 edge_info->rhs = (integer_zerop (op1)
2285 ? boolean_false_node
2286 : boolean_true_node);
2288 edge_info = allocate_edge_info (false_edge);
2289 edge_info->lhs = op0;
2290 edge_info->rhs = (integer_zerop (op1)
2292 : boolean_false_node);
2296 edge_info = allocate_edge_info (true_edge);
2297 edge_info->lhs = op0;
2298 edge_info->rhs = (integer_zerop (op1)
2300 : boolean_false_node);
2302 edge_info = allocate_edge_info (false_edge);
2303 edge_info->lhs = op0;
2304 edge_info->rhs = (integer_zerop (op1)
2305 ? boolean_false_node
2306 : boolean_true_node);
2310 else if (is_gimple_min_invariant (op0)
2311 && (TREE_CODE (op1) == SSA_NAME
2312 || is_gimple_min_invariant (op1)))
2314 tree inverted = invert_truthvalue (cond);
2315 struct edge_info *edge_info;
2317 edge_info = allocate_edge_info (true_edge);
2318 record_conditions (edge_info, cond, inverted);
2320 if (TREE_CODE (cond) == EQ_EXPR)
2322 edge_info->lhs = op1;
2323 edge_info->rhs = op0;
2326 edge_info = allocate_edge_info (false_edge);
2327 record_conditions (edge_info, inverted, cond);
2329 if (TREE_CODE (cond) == NE_EXPR)
2331 edge_info->lhs = op1;
2332 edge_info->rhs = op0;
2336 else if (TREE_CODE (op0) == SSA_NAME
2337 && (is_gimple_min_invariant (op1)
2338 || TREE_CODE (op1) == SSA_NAME))
2340 tree inverted = invert_truthvalue (cond);
2341 struct edge_info *edge_info;
2343 edge_info = allocate_edge_info (true_edge);
2344 record_conditions (edge_info, cond, inverted);
2346 if (TREE_CODE (cond) == EQ_EXPR)
2348 edge_info->lhs = op0;
2349 edge_info->rhs = op1;
2352 edge_info = allocate_edge_info (false_edge);
2353 record_conditions (edge_info, inverted, cond);
2355 if (TREE_CODE (cond) == NE_EXPR)
2357 edge_info->lhs = op0;
2358 edge_info->rhs = op1;
2363 /* ??? TRUTH_NOT_EXPR can create an equivalence too. */
2368 /* Propagate information from BB to its outgoing edges.
2370 This can include equivalency information implied by control statements
2371 at the end of BB and const/copy propagation into PHIs in BB's
2372 successor blocks. */
2375 propagate_to_outgoing_edges (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
2378 record_edge_info (bb);
2379 cprop_into_successor_phis (bb, nonzero_vars);
2382 /* Search for redundant computations in STMT. If any are found, then
2383 replace them with the variable holding the result of the computation.
2385 If safe, record this expression into the available expression hash
2389 eliminate_redundant_computations (tree stmt, stmt_ann_t ann)
2391 tree *expr_p, def = NULL_TREE;
2394 bool retval = false;
2395 bool modify_expr_p = false;
2397 if (TREE_CODE (stmt) == MODIFY_EXPR)
2398 def = TREE_OPERAND (stmt, 0);
2400 /* Certain expressions on the RHS can be optimized away, but can not
2401 themselves be entered into the hash tables. */
2403 || TREE_CODE (def) != SSA_NAME
2404 || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def)
2405 || !ZERO_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF)
2406 /* Do not record equivalences for increments of ivs. This would create
2407 overlapping live ranges for a very questionable gain. */
2408 || simple_iv_increment_p (stmt))
2411 /* Check if the expression has been computed before. */
2412 cached_lhs = lookup_avail_expr (stmt, insert);
2414 /* If this is a COND_EXPR and we did not find its expression in
2415 the hash table, simplify the condition and try again. */
2416 if (! cached_lhs && TREE_CODE (stmt) == COND_EXPR)
2417 cached_lhs = simplify_cond_and_lookup_avail_expr (stmt, ann, insert);
2419 opt_stats.num_exprs_considered++;
2421 /* Get a pointer to the expression we are trying to optimize. */
2422 if (TREE_CODE (stmt) == COND_EXPR)
2423 expr_p = &COND_EXPR_COND (stmt);
2424 else if (TREE_CODE (stmt) == SWITCH_EXPR)
2425 expr_p = &SWITCH_COND (stmt);
2426 else if (TREE_CODE (stmt) == RETURN_EXPR && TREE_OPERAND (stmt, 0))
2428 expr_p = &TREE_OPERAND (TREE_OPERAND (stmt, 0), 1);
2429 modify_expr_p = true;
2433 expr_p = &TREE_OPERAND (stmt, 1);
2434 modify_expr_p = true;
2437 /* It is safe to ignore types here since we have already done
2438 type checking in the hashing and equality routines. In fact
2439 type checking here merely gets in the way of constant
2440 propagation. Also, make sure that it is safe to propagate
2441 CACHED_LHS into *EXPR_P. */
2443 && ((TREE_CODE (cached_lhs) != SSA_NAME
2445 || tree_ssa_useless_type_conversion_1 (TREE_TYPE (*expr_p),
2446 TREE_TYPE (cached_lhs))))
2447 || may_propagate_copy (*expr_p, cached_lhs)))
2449 if (dump_file && (dump_flags & TDF_DETAILS))
2451 fprintf (dump_file, " Replaced redundant expr '");
2452 print_generic_expr (dump_file, *expr_p, dump_flags);
2453 fprintf (dump_file, "' with '");
2454 print_generic_expr (dump_file, cached_lhs, dump_flags);
2455 fprintf (dump_file, "'\n");
2460 #if defined ENABLE_CHECKING
2461 gcc_assert (TREE_CODE (cached_lhs) == SSA_NAME
2462 || is_gimple_min_invariant (cached_lhs));
2465 if (TREE_CODE (cached_lhs) == ADDR_EXPR
2466 || (POINTER_TYPE_P (TREE_TYPE (*expr_p))
2467 && is_gimple_min_invariant (cached_lhs)))
2471 && !tree_ssa_useless_type_conversion_1 (TREE_TYPE (*expr_p),
2472 TREE_TYPE (cached_lhs)))
2473 cached_lhs = fold_convert (TREE_TYPE (*expr_p), cached_lhs);
2475 propagate_tree_value (expr_p, cached_lhs);
2476 mark_stmt_modified (stmt);
2481 /* STMT, a MODIFY_EXPR, may create certain equivalences, in either
2482 the available expressions table or the const_and_copies table.
2483 Detect and record those equivalences. */
2486 record_equivalences_from_stmt (tree stmt,
2490 tree lhs = TREE_OPERAND (stmt, 0);
2491 enum tree_code lhs_code = TREE_CODE (lhs);
2494 if (lhs_code == SSA_NAME)
2496 tree rhs = TREE_OPERAND (stmt, 1);
2498 /* Strip away any useless type conversions. */
2499 STRIP_USELESS_TYPE_CONVERSION (rhs);
2501 /* If the RHS of the assignment is a constant or another variable that
2502 may be propagated, register it in the CONST_AND_COPIES table. We
2503 do not need to record unwind data for this, since this is a true
2504 assignment and not an equivalence inferred from a comparison. All
2505 uses of this ssa name are dominated by this assignment, so unwinding
2506 just costs time and space. */
2508 && (TREE_CODE (rhs) == SSA_NAME
2509 || is_gimple_min_invariant (rhs)))
2510 SSA_NAME_VALUE (lhs) = rhs;
2512 if (tree_expr_nonzero_p (rhs))
2513 record_var_is_nonzero (lhs);
2516 /* Look at both sides for pointer dereferences. If we find one, then
2517 the pointer must be nonnull and we can enter that equivalence into
2519 if (flag_delete_null_pointer_checks)
2520 for (i = 0; i < 2; i++)
2522 tree t = TREE_OPERAND (stmt, i);
2524 /* Strip away any COMPONENT_REFs. */
2525 while (TREE_CODE (t) == COMPONENT_REF)
2526 t = TREE_OPERAND (t, 0);
2528 /* Now see if this is a pointer dereference. */
2529 if (INDIRECT_REF_P (t))
2531 tree op = TREE_OPERAND (t, 0);
2533 /* If the pointer is a SSA variable, then enter new
2534 equivalences into the hash table. */
2535 while (TREE_CODE (op) == SSA_NAME)
2537 tree def = SSA_NAME_DEF_STMT (op);
2539 record_var_is_nonzero (op);
2541 /* And walk up the USE-DEF chains noting other SSA_NAMEs
2542 which are known to have a nonzero value. */
2544 && TREE_CODE (def) == MODIFY_EXPR
2545 && TREE_CODE (TREE_OPERAND (def, 1)) == NOP_EXPR)
2546 op = TREE_OPERAND (TREE_OPERAND (def, 1), 0);
2553 /* A memory store, even an aliased store, creates a useful
2554 equivalence. By exchanging the LHS and RHS, creating suitable
2555 vops and recording the result in the available expression table,
2556 we may be able to expose more redundant loads. */
2557 if (!ann->has_volatile_ops
2558 && (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME
2559 || is_gimple_min_invariant (TREE_OPERAND (stmt, 1)))
2560 && !is_gimple_reg (lhs))
2562 tree rhs = TREE_OPERAND (stmt, 1);
2565 /* FIXME: If the LHS of the assignment is a bitfield and the RHS
2566 is a constant, we need to adjust the constant to fit into the
2567 type of the LHS. If the LHS is a bitfield and the RHS is not
2568 a constant, then we can not record any equivalences for this
2569 statement since we would need to represent the widening or
2570 narrowing of RHS. This fixes gcc.c-torture/execute/921016-1.c
2571 and should not be necessary if GCC represented bitfields
2573 if (lhs_code == COMPONENT_REF
2574 && DECL_BIT_FIELD (TREE_OPERAND (lhs, 1)))
2576 if (TREE_CONSTANT (rhs))
2577 rhs = widen_bitfield (rhs, TREE_OPERAND (lhs, 1), lhs);
2581 /* If the value overflowed, then we can not use this equivalence. */
2582 if (rhs && ! is_gimple_min_invariant (rhs))
2588 /* Build a new statement with the RHS and LHS exchanged. */
2589 new = build2 (MODIFY_EXPR, TREE_TYPE (stmt), rhs, lhs);
2591 create_ssa_artficial_load_stmt (new, stmt);
2593 /* Finally enter the statement into the available expression
2595 lookup_avail_expr (new, true);
2600 /* Replace *OP_P in STMT with any known equivalent value for *OP_P from
2601 CONST_AND_COPIES. */
2604 cprop_operand (tree stmt, use_operand_p op_p)
2606 bool may_have_exposed_new_symbols = false;
2608 tree op = USE_FROM_PTR (op_p);
2610 /* If the operand has a known constant value or it is known to be a
2611 copy of some other variable, use the value or copy stored in
2612 CONST_AND_COPIES. */
2613 val = SSA_NAME_VALUE (op);
2614 if (val && val != op && TREE_CODE (val) != VALUE_HANDLE)
2616 tree op_type, val_type;
2618 /* Do not change the base variable in the virtual operand
2619 tables. That would make it impossible to reconstruct
2620 the renamed virtual operand if we later modify this
2621 statement. Also only allow the new value to be an SSA_NAME
2622 for propagation into virtual operands. */
2623 if (!is_gimple_reg (op)
2624 && (TREE_CODE (val) != SSA_NAME
2625 || is_gimple_reg (val)
2626 || get_virtual_var (val) != get_virtual_var (op)))
2629 /* Do not replace hard register operands in asm statements. */
2630 if (TREE_CODE (stmt) == ASM_EXPR
2631 && !may_propagate_copy_into_asm (op))
2634 /* Get the toplevel type of each operand. */
2635 op_type = TREE_TYPE (op);
2636 val_type = TREE_TYPE (val);
2638 /* While both types are pointers, get the type of the object
2640 while (POINTER_TYPE_P (op_type) && POINTER_TYPE_P (val_type))
2642 op_type = TREE_TYPE (op_type);
2643 val_type = TREE_TYPE (val_type);
2646 /* Make sure underlying types match before propagating a constant by
2647 converting the constant to the proper type. Note that convert may
2648 return a non-gimple expression, in which case we ignore this
2649 propagation opportunity. */
2650 if (TREE_CODE (val) != SSA_NAME)
2652 if (!lang_hooks.types_compatible_p (op_type, val_type))
2654 val = fold_convert (TREE_TYPE (op), val);
2655 if (!is_gimple_min_invariant (val))
2660 /* Certain operands are not allowed to be copy propagated due
2661 to their interaction with exception handling and some GCC
2663 else if (!may_propagate_copy (op, val))
2666 /* Do not propagate copies if the propagated value is at a deeper loop
2667 depth than the propagatee. Otherwise, this may move loop variant
2668 variables outside of their loops and prevent coalescing
2669 opportunities. If the value was loop invariant, it will be hoisted
2670 by LICM and exposed for copy propagation. */
2671 if (loop_depth_of_name (val) > loop_depth_of_name (op))
2675 if (dump_file && (dump_flags & TDF_DETAILS))
2677 fprintf (dump_file, " Replaced '");
2678 print_generic_expr (dump_file, op, dump_flags);
2679 fprintf (dump_file, "' with %s '",
2680 (TREE_CODE (val) != SSA_NAME ? "constant" : "variable"));
2681 print_generic_expr (dump_file, val, dump_flags);
2682 fprintf (dump_file, "'\n");
2685 /* If VAL is an ADDR_EXPR or a constant of pointer type, note
2686 that we may have exposed a new symbol for SSA renaming. */
2687 if (TREE_CODE (val) == ADDR_EXPR
2688 || (POINTER_TYPE_P (TREE_TYPE (op))
2689 && is_gimple_min_invariant (val)))
2690 may_have_exposed_new_symbols = true;
2692 if (TREE_CODE (val) != SSA_NAME)
2693 opt_stats.num_const_prop++;
2695 opt_stats.num_copy_prop++;
2697 propagate_value (op_p, val);
2699 /* And note that we modified this statement. This is now
2700 safe, even if we changed virtual operands since we will
2701 rescan the statement and rewrite its operands again. */
2702 mark_stmt_modified (stmt);
2704 return may_have_exposed_new_symbols;
2707 /* CONST_AND_COPIES is a table which maps an SSA_NAME to the current
2708 known value for that SSA_NAME (or NULL if no value is known).
2710 Propagate values from CONST_AND_COPIES into the uses, vuses and
2711 v_may_def_ops of STMT. */
2714 cprop_into_stmt (tree stmt)
2716 bool may_have_exposed_new_symbols = false;
2720 FOR_EACH_SSA_USE_OPERAND (op_p, stmt, iter, SSA_OP_ALL_USES)
2722 if (TREE_CODE (USE_FROM_PTR (op_p)) == SSA_NAME)
2723 may_have_exposed_new_symbols |= cprop_operand (stmt, op_p);
2726 return may_have_exposed_new_symbols;
2730 /* Optimize the statement pointed to by iterator SI.
2732 We try to perform some simplistic global redundancy elimination and
2733 constant propagation:
2735 1- To detect global redundancy, we keep track of expressions that have
2736 been computed in this block and its dominators. If we find that the
2737 same expression is computed more than once, we eliminate repeated
2738 computations by using the target of the first one.
2740 2- Constant values and copy assignments. This is used to do very
2741 simplistic constant and copy propagation. When a constant or copy
2742 assignment is found, we map the value on the RHS of the assignment to
2743 the variable in the LHS in the CONST_AND_COPIES table. */
2746 optimize_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
2747 basic_block bb, block_stmt_iterator si)
2750 tree stmt, old_stmt;
2751 bool may_optimize_p;
2752 bool may_have_exposed_new_symbols = false;
2754 old_stmt = stmt = bsi_stmt (si);
2756 if (TREE_CODE (stmt) == COND_EXPR)
2757 canonicalize_comparison (stmt);
2759 update_stmt_if_modified (stmt);
2760 ann = stmt_ann (stmt);
2761 opt_stats.num_stmts++;
2762 may_have_exposed_new_symbols = false;
2764 if (dump_file && (dump_flags & TDF_DETAILS))
2766 fprintf (dump_file, "Optimizing statement ");
2767 print_generic_stmt (dump_file, stmt, TDF_SLIM);
2770 /* Const/copy propagate into USES, VUSES and the RHS of V_MAY_DEFs. */
2771 may_have_exposed_new_symbols = cprop_into_stmt (stmt);
2773 /* If the statement has been modified with constant replacements,
2774 fold its RHS before checking for redundant computations. */
2779 /* Try to fold the statement making sure that STMT is kept
2781 if (fold_stmt (bsi_stmt_ptr (si)))
2783 stmt = bsi_stmt (si);
2784 ann = stmt_ann (stmt);
2786 if (dump_file && (dump_flags & TDF_DETAILS))
2788 fprintf (dump_file, " Folded to: ");
2789 print_generic_stmt (dump_file, stmt, TDF_SLIM);
2793 rhs = get_rhs (stmt);
2794 if (rhs && TREE_CODE (rhs) == ADDR_EXPR)
2795 recompute_tree_invariant_for_addr_expr (rhs);
2797 /* Constant/copy propagation above may change the set of
2798 virtual operands associated with this statement. Folding
2799 may remove the need for some virtual operands.
2801 Indicate we will need to rescan and rewrite the statement. */
2802 may_have_exposed_new_symbols = true;
2805 /* Check for redundant computations. Do this optimization only
2806 for assignments that have no volatile ops and conditionals. */
2807 may_optimize_p = (!ann->has_volatile_ops
2808 && ((TREE_CODE (stmt) == RETURN_EXPR
2809 && TREE_OPERAND (stmt, 0)
2810 && TREE_CODE (TREE_OPERAND (stmt, 0)) == MODIFY_EXPR
2811 && ! (TREE_SIDE_EFFECTS
2812 (TREE_OPERAND (TREE_OPERAND (stmt, 0), 1))))
2813 || (TREE_CODE (stmt) == MODIFY_EXPR
2814 && ! TREE_SIDE_EFFECTS (TREE_OPERAND (stmt, 1)))
2815 || TREE_CODE (stmt) == COND_EXPR
2816 || TREE_CODE (stmt) == SWITCH_EXPR));
2819 may_have_exposed_new_symbols
2820 |= eliminate_redundant_computations (stmt, ann);
2822 /* Record any additional equivalences created by this statement. */
2823 if (TREE_CODE (stmt) == MODIFY_EXPR)
2824 record_equivalences_from_stmt (stmt,
2828 /* If STMT is a COND_EXPR and it was modified, then we may know
2829 where it goes. If that is the case, then mark the CFG as altered.
2831 This will cause us to later call remove_unreachable_blocks and
2832 cleanup_tree_cfg when it is safe to do so. It is not safe to
2833 clean things up here since removal of edges and such can trigger
2834 the removal of PHI nodes, which in turn can release SSA_NAMEs to
2837 That's all fine and good, except that once SSA_NAMEs are released
2838 to the manager, we must not call create_ssa_name until all references
2839 to released SSA_NAMEs have been eliminated.
2841 All references to the deleted SSA_NAMEs can not be eliminated until
2842 we remove unreachable blocks.
2844 We can not remove unreachable blocks until after we have completed
2845 any queued jump threading.
2847 We can not complete any queued jump threads until we have taken
2848 appropriate variables out of SSA form. Taking variables out of
2849 SSA form can call create_ssa_name and thus we lose.
2851 Ultimately I suspect we're going to need to change the interface
2852 into the SSA_NAME manager. */
2858 if (TREE_CODE (stmt) == COND_EXPR)
2859 val = COND_EXPR_COND (stmt);
2860 else if (TREE_CODE (stmt) == SWITCH_EXPR)
2861 val = SWITCH_COND (stmt);
2863 if (val && TREE_CODE (val) == INTEGER_CST && find_taken_edge (bb, val))
2866 /* If we simplified a statement in such a way as to be shown that it
2867 cannot trap, update the eh information and the cfg to match. */
2868 if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
2870 bitmap_set_bit (need_eh_cleanup, bb->index);
2871 if (dump_file && (dump_flags & TDF_DETAILS))
2872 fprintf (dump_file, " Flagged to clear EH edges.\n");
2876 if (may_have_exposed_new_symbols)
2877 VEC_safe_push (tree, heap, stmts_to_rescan, bsi_stmt (si));
2880 /* Search for an existing instance of STMT in the AVAIL_EXPRS table. If
2881 found, return its LHS. Otherwise insert STMT in the table and return
2884 Also, when an expression is first inserted in the AVAIL_EXPRS table, it
2885 is also added to the stack pointed to by BLOCK_AVAIL_EXPRS_P, so that they
2886 can be removed when we finish processing this block and its children.
2888 NOTE: This function assumes that STMT is a MODIFY_EXPR node that
2889 contains no CALL_EXPR on its RHS and makes no volatile nor
2890 aliased references. */
2893 lookup_avail_expr (tree stmt, bool insert)
2898 struct expr_hash_elt *element = XNEW (struct expr_hash_elt);
2900 lhs = TREE_CODE (stmt) == MODIFY_EXPR ? TREE_OPERAND (stmt, 0) : NULL;
2902 initialize_hash_element (stmt, lhs, element);
2904 /* Don't bother remembering constant assignments and copy operations.
2905 Constants and copy operations are handled by the constant/copy propagator
2906 in optimize_stmt. */
2907 if (TREE_CODE (element->rhs) == SSA_NAME
2908 || is_gimple_min_invariant (element->rhs))
2914 /* If this is an equality test against zero, see if we have recorded a
2915 nonzero value for the variable in question. */
2916 if ((TREE_CODE (element->rhs) == EQ_EXPR
2917 || TREE_CODE (element->rhs) == NE_EXPR)
2918 && TREE_CODE (TREE_OPERAND (element->rhs, 0)) == SSA_NAME
2919 && integer_zerop (TREE_OPERAND (element->rhs, 1)))
2921 int indx = SSA_NAME_VERSION (TREE_OPERAND (element->rhs, 0));
2923 if (bitmap_bit_p (nonzero_vars, indx))
2925 tree t = element->rhs;
2927 return constant_boolean_node (TREE_CODE (t) != EQ_EXPR,
2932 /* Finally try to find the expression in the main expression hash table. */
2933 slot = htab_find_slot_with_hash (avail_exprs, element, element->hash,
2934 (insert ? INSERT : NO_INSERT));
2943 *slot = (void *) element;
2944 VEC_safe_push (tree, heap, avail_exprs_stack,
2945 stmt ? stmt : element->rhs);
2949 /* Extract the LHS of the assignment so that it can be used as the current
2950 definition of another variable. */
2951 lhs = ((struct expr_hash_elt *)*slot)->lhs;
2953 /* See if the LHS appears in the CONST_AND_COPIES table. If it does, then
2954 use the value from the const_and_copies table. */
2955 if (TREE_CODE (lhs) == SSA_NAME)
2957 temp = SSA_NAME_VALUE (lhs);
2958 if (temp && TREE_CODE (temp) != VALUE_HANDLE)
2966 /* Given a condition COND, record into HI_P, LO_P and INVERTED_P the
2967 range of values that result in the conditional having a true value.
2969 Return true if we are successful in extracting a range from COND and
2970 false if we are unsuccessful. */
2973 extract_range_from_cond (tree cond, tree *hi_p, tree *lo_p, int *inverted_p)
2975 tree op1 = TREE_OPERAND (cond, 1);
2976 tree high, low, type;
2979 type = TREE_TYPE (op1);
2981 /* Experiments have shown that it's rarely, if ever useful to
2982 record ranges for enumerations. Presumably this is due to
2983 the fact that they're rarely used directly. They are typically
2984 cast into an integer type and used that way. */
2985 if (TREE_CODE (type) != INTEGER_TYPE)
2988 switch (TREE_CODE (cond))
3003 /* Get the highest value of the type. If not a constant, use that
3004 of its base type, if it has one. */
3005 high = TYPE_MAX_VALUE (type);
3006 if (TREE_CODE (high) != INTEGER_CST && TREE_TYPE (type))
3007 high = TYPE_MAX_VALUE (TREE_TYPE (type));
3012 high = TYPE_MAX_VALUE (type);
3013 if (TREE_CODE (high) != INTEGER_CST && TREE_TYPE (type))
3014 high = TYPE_MAX_VALUE (TREE_TYPE (type));
3015 if (!tree_int_cst_lt (op1, high))
3017 low = int_const_binop (PLUS_EXPR, op1, integer_one_node, 1);
3023 low = TYPE_MIN_VALUE (type);
3024 if (TREE_CODE (low) != INTEGER_CST && TREE_TYPE (type))
3025 low = TYPE_MIN_VALUE (TREE_TYPE (type));
3030 low = TYPE_MIN_VALUE (type);
3031 if (TREE_CODE (low) != INTEGER_CST && TREE_TYPE (type))
3032 low = TYPE_MIN_VALUE (TREE_TYPE (type));
3033 if (!tree_int_cst_lt (low, op1))
3035 high = int_const_binop (MINUS_EXPR, op1, integer_one_node, 1);
3045 *inverted_p = inverted;
3049 /* Record a range created by COND for basic block BB. */
3052 record_range (tree cond, basic_block bb)
3054 enum tree_code code = TREE_CODE (cond);
3056 /* We explicitly ignore NE_EXPRs and all the unordered comparisons.
3057 They rarely allow for meaningful range optimizations and significantly
3058 complicate the implementation. */
3059 if ((code == LT_EXPR || code == LE_EXPR || code == GT_EXPR
3060 || code == GE_EXPR || code == EQ_EXPR)
3061 && TREE_CODE (TREE_TYPE (TREE_OPERAND (cond, 1))) == INTEGER_TYPE)
3063 struct vrp_hash_elt *vrp_hash_elt;
3064 struct vrp_element *element;
3065 VEC(vrp_element_p,heap) **vrp_records_p;
3069 vrp_hash_elt = XNEW (struct vrp_hash_elt);
3070 vrp_hash_elt->var = TREE_OPERAND (cond, 0);
3071 vrp_hash_elt->records = NULL;
3072 slot = htab_find_slot (vrp_data, vrp_hash_elt, INSERT);
3075 *slot = (void *) vrp_hash_elt;
3077 vrp_free (vrp_hash_elt);
3079 vrp_hash_elt = (struct vrp_hash_elt *) *slot;
3080 vrp_records_p = &vrp_hash_elt->records;
3082 element = GGC_NEW (struct vrp_element);
3083 element->low = NULL;
3084 element->high = NULL;
3085 element->cond = cond;
3088 VEC_safe_push (vrp_element_p, heap, *vrp_records_p, element);
3089 VEC_safe_push (tree, heap, vrp_variables_stack, TREE_OPERAND (cond, 0));
3093 /* Hashing and equality functions for VRP_DATA.
3095 Since this hash table is addressed by SSA_NAMEs, we can hash on
3096 their version number and equality can be determined with a
3097 pointer comparison. */
3100 vrp_hash (const void *p)
3102 tree var = ((struct vrp_hash_elt *)p)->var;
3104 return SSA_NAME_VERSION (var);
3108 vrp_eq (const void *p1, const void *p2)
3110 tree var1 = ((struct vrp_hash_elt *)p1)->var;
3111 tree var2 = ((struct vrp_hash_elt *)p2)->var;
3113 return var1 == var2;
3116 /* Hashing and equality functions for AVAIL_EXPRS. The table stores
3117 MODIFY_EXPR statements. We compute a value number for expressions using
3118 the code of the expression and the SSA numbers of its operands. */
3121 avail_expr_hash (const void *p)
3123 tree stmt = ((struct expr_hash_elt *)p)->stmt;
3124 tree rhs = ((struct expr_hash_elt *)p)->rhs;
3129 /* iterative_hash_expr knows how to deal with any expression and
3130 deals with commutative operators as well, so just use it instead
3131 of duplicating such complexities here. */
3132 val = iterative_hash_expr (rhs, val);
3134 /* If the hash table entry is not associated with a statement, then we
3135 can just hash the expression and not worry about virtual operands
3137 if (!stmt || !stmt_ann (stmt))
3140 /* Add the SSA version numbers of every vuse operand. This is important
3141 because compound variables like arrays are not renamed in the
3142 operands. Rather, the rename is done on the virtual variable
3143 representing all the elements of the array. */
3144 FOR_EACH_SSA_TREE_OPERAND (vuse, stmt, iter, SSA_OP_VUSE)
3145 val = iterative_hash_expr (vuse, val);
3151 real_avail_expr_hash (const void *p)
3153 return ((const struct expr_hash_elt *)p)->hash;
3157 avail_expr_eq (const void *p1, const void *p2)
3159 tree stmt1 = ((struct expr_hash_elt *)p1)->stmt;
3160 tree rhs1 = ((struct expr_hash_elt *)p1)->rhs;
3161 tree stmt2 = ((struct expr_hash_elt *)p2)->stmt;
3162 tree rhs2 = ((struct expr_hash_elt *)p2)->rhs;
3164 /* If they are the same physical expression, return true. */
3165 if (rhs1 == rhs2 && stmt1 == stmt2)
3168 /* If their codes are not equal, then quit now. */
3169 if (TREE_CODE (rhs1) != TREE_CODE (rhs2))
3172 /* In case of a collision, both RHS have to be identical and have the
3173 same VUSE operands. */
3174 if ((TREE_TYPE (rhs1) == TREE_TYPE (rhs2)
3175 || lang_hooks.types_compatible_p (TREE_TYPE (rhs1), TREE_TYPE (rhs2)))
3176 && operand_equal_p (rhs1, rhs2, OEP_PURE_SAME))
3178 bool ret = compare_ssa_operands_equal (stmt1, stmt2, SSA_OP_VUSE);
3179 gcc_assert (!ret || ((struct expr_hash_elt *)p1)->hash
3180 == ((struct expr_hash_elt *)p2)->hash);