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 simplify_switch_and_lookup_avail_expr (tree, int);
278 static tree find_equivalent_equality_comparison (tree);
279 static void record_range (tree, basic_block);
280 static bool extract_range_from_cond (tree, tree *, tree *, int *);
281 static void record_equivalences_from_phis (basic_block);
282 static void record_equivalences_from_incoming_edge (basic_block);
283 static bool eliminate_redundant_computations (tree, stmt_ann_t);
284 static void record_equivalences_from_stmt (tree, int, stmt_ann_t);
285 static void thread_across_edge (struct dom_walk_data *, edge);
286 static void dom_opt_finalize_block (struct dom_walk_data *, basic_block);
287 static void dom_opt_initialize_block (struct dom_walk_data *, basic_block);
288 static void propagate_to_outgoing_edges (struct dom_walk_data *, basic_block);
289 static void remove_local_expressions_from_table (void);
290 static void restore_vars_to_original_value (void);
291 static edge single_incoming_edge_ignoring_loop_edges (basic_block);
292 static void restore_nonzero_vars_to_original_value (void);
293 static inline bool unsafe_associative_fp_binop (tree);
296 /* Local version of fold that doesn't introduce cruft. */
303 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that
304 may have been added by fold, and "useless" type conversions that might
305 now be apparent due to propagation. */
306 STRIP_USELESS_TYPE_CONVERSION (t);
311 /* Allocate an EDGE_INFO for edge E and attach it to E.
312 Return the new EDGE_INFO structure. */
314 static struct edge_info *
315 allocate_edge_info (edge e)
317 struct edge_info *edge_info;
319 edge_info = xcalloc (1, sizeof (struct edge_info));
325 /* Free all EDGE_INFO structures associated with edges in the CFG.
326 If a particular edge can be threaded, copy the redirection
327 target from the EDGE_INFO structure into the edge's AUX field
328 as required by code to update the CFG and SSA graph for
332 free_all_edge_infos (void)
340 FOR_EACH_EDGE (e, ei, bb->preds)
342 struct edge_info *edge_info = e->aux;
346 e->aux = edge_info->redirection_target;
347 if (edge_info->cond_equivalences)
348 free (edge_info->cond_equivalences);
355 /* Free an instance of vrp_hash_elt. */
358 vrp_free (void *data)
360 struct vrp_hash_elt *elt = data;
361 struct VEC(vrp_element_p,heap) **vrp_elt = &elt->records;
363 VEC_free (vrp_element_p, heap, *vrp_elt);
367 /* Jump threading, redundancy elimination and const/copy propagation.
369 This pass may expose new symbols that need to be renamed into SSA. For
370 every new symbol exposed, its corresponding bit will be set in
374 tree_ssa_dominator_optimize (void)
376 struct dom_walk_data walk_data;
378 struct loops loops_info;
380 memset (&opt_stats, 0, sizeof (opt_stats));
382 /* Create our hash tables. */
383 avail_exprs = htab_create (1024, real_avail_expr_hash, avail_expr_eq, free);
384 vrp_data = htab_create (ceil_log2 (num_ssa_names), vrp_hash, vrp_eq,
386 avail_exprs_stack = VEC_alloc (tree, heap, 20);
387 const_and_copies_stack = VEC_alloc (tree, heap, 20);
388 nonzero_vars_stack = VEC_alloc (tree, heap, 20);
389 vrp_variables_stack = VEC_alloc (tree, heap, 20);
390 stmts_to_rescan = VEC_alloc (tree, heap, 20);
391 nonzero_vars = BITMAP_ALLOC (NULL);
392 threaded_blocks = BITMAP_ALLOC (NULL);
393 need_eh_cleanup = BITMAP_ALLOC (NULL);
395 /* Setup callbacks for the generic dominator tree walker. */
396 walk_data.walk_stmts_backward = false;
397 walk_data.dom_direction = CDI_DOMINATORS;
398 walk_data.initialize_block_local_data = NULL;
399 walk_data.before_dom_children_before_stmts = dom_opt_initialize_block;
400 walk_data.before_dom_children_walk_stmts = optimize_stmt;
401 walk_data.before_dom_children_after_stmts = propagate_to_outgoing_edges;
402 walk_data.after_dom_children_before_stmts = NULL;
403 walk_data.after_dom_children_walk_stmts = NULL;
404 walk_data.after_dom_children_after_stmts = dom_opt_finalize_block;
405 /* Right now we only attach a dummy COND_EXPR to the global data pointer.
406 When we attach more stuff we'll need to fill this out with a real
408 walk_data.global_data = NULL;
409 walk_data.block_local_data_size = 0;
410 walk_data.interesting_blocks = NULL;
412 /* Now initialize the dominator walker. */
413 init_walk_dominator_tree (&walk_data);
415 calculate_dominance_info (CDI_DOMINATORS);
417 /* We need to know which edges exit loops so that we can
418 aggressively thread through loop headers to an exit
420 flow_loops_find (&loops_info);
421 mark_loop_exit_edges (&loops_info);
422 flow_loops_free (&loops_info);
424 /* Clean up the CFG so that any forwarder blocks created by loop
425 canonicalization are removed. */
427 calculate_dominance_info (CDI_DOMINATORS);
429 /* If we prove certain blocks are unreachable, then we want to
430 repeat the dominator optimization process as PHI nodes may
431 have turned into copies which allows better propagation of
432 values. So we repeat until we do not identify any new unreachable
436 /* Optimize the dominator tree. */
439 /* We need accurate information regarding back edges in the CFG
440 for jump threading. */
441 mark_dfs_back_edges ();
443 /* Recursively walk the dominator tree optimizing statements. */
444 walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
447 block_stmt_iterator bsi;
451 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
453 update_stmt_if_modified (bsi_stmt (bsi));
458 /* If we exposed any new variables, go ahead and put them into
459 SSA form now, before we handle jump threading. This simplifies
460 interactions between rewriting of _DECL nodes into SSA form
461 and rewriting SSA_NAME nodes into SSA form after block
462 duplication and CFG manipulation. */
463 update_ssa (TODO_update_ssa);
465 free_all_edge_infos ();
467 /* Thread jumps, creating duplicate blocks as needed. */
468 cfg_altered |= thread_through_all_blocks (threaded_blocks);
470 /* Removal of statements may make some EH edges dead. Purge
471 such edges from the CFG as needed. */
472 if (!bitmap_empty_p (need_eh_cleanup))
474 cfg_altered |= tree_purge_all_dead_eh_edges (need_eh_cleanup);
475 bitmap_zero (need_eh_cleanup);
479 free_dominance_info (CDI_DOMINATORS);
481 /* Only iterate if we threaded jumps AND the CFG cleanup did
482 something interesting. Other cases generate far fewer
483 optimization opportunities and thus are not worth another
484 full DOM iteration. */
485 cfg_altered &= cleanup_tree_cfg ();
487 if (rediscover_loops_after_threading)
489 /* Rerun basic loop analysis to discover any newly
490 created loops and update the set of exit edges. */
491 rediscover_loops_after_threading = false;
492 flow_loops_find (&loops_info);
493 mark_loop_exit_edges (&loops_info);
494 flow_loops_free (&loops_info);
496 /* Remove any forwarder blocks inserted by loop
497 header canonicalization. */
501 calculate_dominance_info (CDI_DOMINATORS);
503 update_ssa (TODO_update_ssa);
505 /* Reinitialize the various tables. */
506 bitmap_clear (nonzero_vars);
507 bitmap_clear (threaded_blocks);
508 htab_empty (avail_exprs);
509 htab_empty (vrp_data);
511 /* Finally, remove everything except invariants in SSA_NAME_VALUE.
513 This must be done before we iterate as we might have a
514 reference to an SSA_NAME which was removed by the call to
517 Long term we will be able to let everything in SSA_NAME_VALUE
518 persist. However, for now, we know this is the safe thing to do. */
519 for (i = 0; i < num_ssa_names; i++)
521 tree name = ssa_name (i);
527 value = SSA_NAME_VALUE (name);
528 if (value && !is_gimple_min_invariant (value))
529 SSA_NAME_VALUE (name) = NULL;
532 opt_stats.num_iterations++;
534 while (optimize > 1 && cfg_altered);
536 /* Debugging dumps. */
537 if (dump_file && (dump_flags & TDF_STATS))
538 dump_dominator_optimization_stats (dump_file);
540 /* We emptied the hash table earlier, now delete it completely. */
541 htab_delete (avail_exprs);
542 htab_delete (vrp_data);
544 /* It is not necessary to clear CURRDEFS, REDIRECTION_EDGES, VRP_DATA,
545 CONST_AND_COPIES, and NONZERO_VARS as they all get cleared at the bottom
546 of the do-while loop above. */
548 /* And finalize the dominator walker. */
549 fini_walk_dominator_tree (&walk_data);
551 /* Free nonzero_vars. */
552 BITMAP_FREE (nonzero_vars);
553 BITMAP_FREE (threaded_blocks);
554 BITMAP_FREE (need_eh_cleanup);
556 VEC_free (tree, heap, avail_exprs_stack);
557 VEC_free (tree, heap, const_and_copies_stack);
558 VEC_free (tree, heap, nonzero_vars_stack);
559 VEC_free (tree, heap, vrp_variables_stack);
560 VEC_free (tree, heap, stmts_to_rescan);
564 gate_dominator (void)
566 return flag_tree_dom != 0;
569 struct tree_opt_pass pass_dominator =
572 gate_dominator, /* gate */
573 tree_ssa_dominator_optimize, /* execute */
576 0, /* static_pass_number */
577 TV_TREE_SSA_DOMINATOR_OPTS, /* tv_id */
578 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
579 0, /* properties_provided */
580 0, /* properties_destroyed */
581 0, /* todo_flags_start */
584 | TODO_verify_ssa, /* todo_flags_finish */
589 /* Given a stmt CONDSTMT containing a COND_EXPR, canonicalize the
590 COND_EXPR into a canonical form. */
593 canonicalize_comparison (tree condstmt)
595 tree cond = COND_EXPR_COND (condstmt);
598 enum tree_code code = TREE_CODE (cond);
600 if (!COMPARISON_CLASS_P (cond))
603 op0 = TREE_OPERAND (cond, 0);
604 op1 = TREE_OPERAND (cond, 1);
606 /* If it would be profitable to swap the operands, then do so to
607 canonicalize the statement, enabling better optimization.
609 By placing canonicalization of such expressions here we
610 transparently keep statements in canonical form, even
611 when the statement is modified. */
612 if (tree_swap_operands_p (op0, op1, false))
614 /* For relationals we need to swap the operands
615 and change the code. */
621 TREE_SET_CODE (cond, swap_tree_comparison (code));
622 swap_tree_operands (condstmt,
623 &TREE_OPERAND (cond, 0),
624 &TREE_OPERAND (cond, 1));
625 /* If one operand was in the operand cache, but the other is
626 not, because it is a constant, this is a case that the
627 internal updating code of swap_tree_operands can't handle
629 if (TREE_CODE_CLASS (TREE_CODE (op0))
630 != TREE_CODE_CLASS (TREE_CODE (op1)))
631 update_stmt (condstmt);
635 /* We are exiting E->src, see if E->dest ends with a conditional
636 jump which has a known value when reached via E.
638 Special care is necessary if E is a back edge in the CFG as we
639 will have already recorded equivalences for E->dest into our
640 various tables, including the result of the conditional at
641 the end of E->dest. Threading opportunities are severely
642 limited in that case to avoid short-circuiting the loop
645 Note it is quite common for the first block inside a loop to
646 end with a conditional which is either always true or always
647 false when reached via the loop backedge. Thus we do not want
648 to blindly disable threading across a loop backedge. */
651 thread_across_edge (struct dom_walk_data *walk_data, edge e)
653 block_stmt_iterator bsi;
660 /* If E->dest does not end with a conditional, then there is
662 bsi = bsi_last (e->dest);
665 || (TREE_CODE (bsi_stmt (bsi)) != COND_EXPR
666 && TREE_CODE (bsi_stmt (bsi)) != GOTO_EXPR
667 && TREE_CODE (bsi_stmt (bsi)) != SWITCH_EXPR))
670 /* The basic idea here is to use whatever knowledge we have
671 from our dominator walk to simplify statements in E->dest,
672 with the ultimate goal being to simplify the conditional
673 at the end of E->dest.
675 Note that we must undo any changes we make to the underlying
676 statements as the simplifications we are making are control
677 flow sensitive (ie, the simplifications are valid when we
678 traverse E, but may not be valid on other paths to E->dest. */
680 /* Each PHI creates a temporary equivalence, record them. Again
681 these are context sensitive equivalences and will be removed
683 for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
685 tree src = PHI_ARG_DEF_FROM_EDGE (phi, e);
686 tree dst = PHI_RESULT (phi);
688 /* Do not include virtual PHIs in our statement count as
689 they never generate code. */
690 if (is_gimple_reg (dst))
693 /* If the desired argument is not the same as this PHI's result
694 and it is set by a PHI in E->dest, then we can not thread
697 && TREE_CODE (src) == SSA_NAME
698 && TREE_CODE (SSA_NAME_DEF_STMT (src)) == PHI_NODE
699 && bb_for_stmt (SSA_NAME_DEF_STMT (src)) == e->dest)
702 record_const_or_copy (dst, src);
705 /* Try to simplify each statement in E->dest, ultimately leading to
706 a simplification of the COND_EXPR at the end of E->dest.
708 We might consider marking just those statements which ultimately
709 feed the COND_EXPR. It's not clear if the overhead of bookkeeping
710 would be recovered by trying to simplify fewer statements.
712 If we are able to simplify a statement into the form
713 SSA_NAME = (SSA_NAME | gimple invariant), then we can record
714 a context sensitive equivalency which may help us simplify
715 later statements in E->dest.
717 Failure to simplify into the form above merely means that the
718 statement provides no equivalences to help simplify later
719 statements. This does not prevent threading through E->dest. */
720 max_stmt_count = PARAM_VALUE (PARAM_MAX_JUMP_THREAD_DUPLICATION_STMTS);
721 for (bsi = bsi_start (e->dest); ! bsi_end_p (bsi); bsi_next (&bsi))
723 tree cached_lhs = NULL;
725 stmt = bsi_stmt (bsi);
727 /* Ignore empty statements and labels. */
728 if (IS_EMPTY_STMT (stmt) || TREE_CODE (stmt) == LABEL_EXPR)
731 /* If duplicating this block is going to cause too much code
732 expansion, then do not thread through this block. */
734 if (stmt_count > max_stmt_count)
737 /* Safely handle threading across loop backedges. This is
738 over conservative, but still allows us to capture the
739 majority of the cases where we can thread across a loop
741 if ((e->flags & EDGE_DFS_BACK) != 0
742 && TREE_CODE (stmt) != COND_EXPR
743 && TREE_CODE (stmt) != SWITCH_EXPR)
746 /* If the statement has volatile operands, then we assume we
747 can not thread through this block. This is overly
748 conservative in some ways. */
749 if (TREE_CODE (stmt) == ASM_EXPR && ASM_VOLATILE_P (stmt))
752 /* If this is not a MODIFY_EXPR which sets an SSA_NAME to a new
753 value, then do not try to simplify this statement as it will
754 not simplify in any way that is helpful for jump threading. */
755 if (TREE_CODE (stmt) != MODIFY_EXPR
756 || TREE_CODE (TREE_OPERAND (stmt, 0)) != SSA_NAME)
759 /* At this point we have a statement which assigns an RHS to an
760 SSA_VAR on the LHS. We want to try and simplify this statement
761 to expose more context sensitive equivalences which in turn may
762 allow us to simplify the condition at the end of the loop. */
763 if (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME)
764 cached_lhs = TREE_OPERAND (stmt, 1);
767 /* Copy the operands. */
768 tree *copy, pre_fold_expr;
771 unsigned int num, i = 0;
773 num = NUM_SSA_OPERANDS (stmt, (SSA_OP_USE | SSA_OP_VUSE));
774 copy = xcalloc (num, sizeof (tree));
776 /* Make a copy of the uses & vuses into USES_COPY, then cprop into
778 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
781 tree use = USE_FROM_PTR (use_p);
784 if (TREE_CODE (use) == SSA_NAME)
785 tmp = SSA_NAME_VALUE (use);
786 if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
787 SET_USE (use_p, tmp);
790 /* Try to fold/lookup the new expression. Inserting the
791 expression into the hash table is unlikely to help
792 Sadly, we have to handle conditional assignments specially
793 here, because fold expects all the operands of an expression
794 to be folded before the expression itself is folded, but we
795 can't just substitute the folded condition here. */
796 if (TREE_CODE (TREE_OPERAND (stmt, 1)) == COND_EXPR)
798 tree cond = COND_EXPR_COND (TREE_OPERAND (stmt, 1));
800 if (cond == boolean_true_node)
801 pre_fold_expr = COND_EXPR_THEN (TREE_OPERAND (stmt, 1));
802 else if (cond == boolean_false_node)
803 pre_fold_expr = COND_EXPR_ELSE (TREE_OPERAND (stmt, 1));
805 pre_fold_expr = TREE_OPERAND (stmt, 1);
808 pre_fold_expr = TREE_OPERAND (stmt, 1);
812 cached_lhs = fold (pre_fold_expr);
813 if (TREE_CODE (cached_lhs) != SSA_NAME
814 && !is_gimple_min_invariant (cached_lhs))
815 cached_lhs = lookup_avail_expr (stmt, false);
818 /* Restore the statement's original uses/defs. */
820 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE | SSA_OP_VUSE)
821 SET_USE (use_p, copy[i++]);
826 /* Record the context sensitive equivalence if we were able
827 to simplify this statement. */
829 && (TREE_CODE (cached_lhs) == SSA_NAME
830 || is_gimple_min_invariant (cached_lhs)))
831 record_const_or_copy (TREE_OPERAND (stmt, 0), cached_lhs);
834 /* If we stopped at a COND_EXPR or SWITCH_EXPR, see if we know which arm
837 && (TREE_CODE (stmt) == COND_EXPR
838 || TREE_CODE (stmt) == GOTO_EXPR
839 || TREE_CODE (stmt) == SWITCH_EXPR))
841 tree cond, cached_lhs;
843 /* Now temporarily cprop the operands and try to find the resulting
844 expression in the hash tables. */
845 if (TREE_CODE (stmt) == COND_EXPR)
847 canonicalize_comparison (stmt);
848 cond = COND_EXPR_COND (stmt);
850 else if (TREE_CODE (stmt) == GOTO_EXPR)
851 cond = GOTO_DESTINATION (stmt);
853 cond = SWITCH_COND (stmt);
855 if (COMPARISON_CLASS_P (cond))
857 tree dummy_cond, op0, op1;
858 enum tree_code cond_code;
860 op0 = TREE_OPERAND (cond, 0);
861 op1 = TREE_OPERAND (cond, 1);
862 cond_code = TREE_CODE (cond);
864 /* Get the current value of both operands. */
865 if (TREE_CODE (op0) == SSA_NAME)
867 tree tmp = SSA_NAME_VALUE (op0);
868 if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
872 if (TREE_CODE (op1) == SSA_NAME)
874 tree tmp = SSA_NAME_VALUE (op1);
875 if (tmp && TREE_CODE (tmp) != VALUE_HANDLE)
879 /* Stuff the operator and operands into our dummy conditional
880 expression, creating the dummy conditional if necessary. */
881 dummy_cond = walk_data->global_data;
884 dummy_cond = build2 (cond_code, boolean_type_node, op0, op1);
885 dummy_cond = build3 (COND_EXPR, void_type_node,
886 dummy_cond, NULL_TREE, NULL_TREE);
887 walk_data->global_data = dummy_cond;
891 TREE_SET_CODE (COND_EXPR_COND (dummy_cond), cond_code);
892 TREE_OPERAND (COND_EXPR_COND (dummy_cond), 0) = op0;
893 TREE_OPERAND (COND_EXPR_COND (dummy_cond), 1) = op1;
896 /* If the conditional folds to an invariant, then we are done,
897 otherwise look it up in the hash tables. */
898 cached_lhs = local_fold (COND_EXPR_COND (dummy_cond));
899 if (! is_gimple_min_invariant (cached_lhs))
901 cached_lhs = lookup_avail_expr (dummy_cond, false);
902 if (!cached_lhs || ! is_gimple_min_invariant (cached_lhs))
903 cached_lhs = simplify_cond_and_lookup_avail_expr (dummy_cond,
908 /* We can have conditionals which just test the state of a
909 variable rather than use a relational operator. These are
910 simpler to handle. */
911 else if (TREE_CODE (cond) == SSA_NAME)
914 cached_lhs = SSA_NAME_VALUE (cached_lhs);
915 if (cached_lhs && ! is_gimple_min_invariant (cached_lhs))
919 cached_lhs = lookup_avail_expr (stmt, false);
923 edge taken_edge = find_taken_edge (e->dest, cached_lhs);
924 basic_block dest = (taken_edge ? taken_edge->dest : NULL);
929 /* If we have a known destination for the conditional, then
930 we can perform this optimization, which saves at least one
931 conditional jump each time it applies since we get to
932 bypass the conditional at our original destination. */
935 struct edge_info *edge_info;
940 edge_info = allocate_edge_info (e);
941 edge_info->redirection_target = taken_edge;
942 bitmap_set_bit (threaded_blocks, e->dest->index);
949 /* Initialize local stacks for this optimizer and record equivalences
950 upon entry to BB. Equivalences can come from the edge traversed to
951 reach BB or they may come from PHI nodes at the start of BB. */
954 dom_opt_initialize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
957 if (dump_file && (dump_flags & TDF_DETAILS))
958 fprintf (dump_file, "\n\nOptimizing block #%d\n\n", bb->index);
960 /* Push a marker on the stacks of local information so that we know how
961 far to unwind when we finalize this block. */
962 VEC_safe_push (tree, heap, avail_exprs_stack, NULL_TREE);
963 VEC_safe_push (tree, heap, const_and_copies_stack, NULL_TREE);
964 VEC_safe_push (tree, heap, nonzero_vars_stack, NULL_TREE);
965 VEC_safe_push (tree, heap, vrp_variables_stack, NULL_TREE);
967 record_equivalences_from_incoming_edge (bb);
969 /* PHI nodes can create equivalences too. */
970 record_equivalences_from_phis (bb);
973 /* Given an expression EXPR (a relational expression or a statement),
974 initialize the hash table element pointed to by ELEMENT. */
977 initialize_hash_element (tree expr, tree lhs, struct expr_hash_elt *element)
979 /* Hash table elements may be based on conditional expressions or statements.
981 For the former case, we have no annotation and we want to hash the
982 conditional expression. In the latter case we have an annotation and
983 we want to record the expression the statement evaluates. */
984 if (COMPARISON_CLASS_P (expr) || TREE_CODE (expr) == TRUTH_NOT_EXPR)
986 element->stmt = NULL;
989 else if (TREE_CODE (expr) == COND_EXPR)
991 element->stmt = expr;
992 element->rhs = COND_EXPR_COND (expr);
994 else if (TREE_CODE (expr) == SWITCH_EXPR)
996 element->stmt = expr;
997 element->rhs = SWITCH_COND (expr);
999 else if (TREE_CODE (expr) == RETURN_EXPR && TREE_OPERAND (expr, 0))
1001 element->stmt = expr;
1002 element->rhs = TREE_OPERAND (TREE_OPERAND (expr, 0), 1);
1004 else if (TREE_CODE (expr) == GOTO_EXPR)
1006 element->stmt = expr;
1007 element->rhs = GOTO_DESTINATION (expr);
1011 element->stmt = expr;
1012 element->rhs = TREE_OPERAND (expr, 1);
1016 element->hash = avail_expr_hash (element);
1019 /* Remove all the expressions in LOCALS from TABLE, stopping when there are
1020 LIMIT entries left in LOCALs. */
1023 remove_local_expressions_from_table (void)
1025 /* Remove all the expressions made available in this block. */
1026 while (VEC_length (tree, avail_exprs_stack) > 0)
1028 struct expr_hash_elt element;
1029 tree expr = VEC_pop (tree, avail_exprs_stack);
1031 if (expr == NULL_TREE)
1034 initialize_hash_element (expr, NULL, &element);
1035 htab_remove_elt_with_hash (avail_exprs, &element, element.hash);
1039 /* Use the SSA_NAMES in LOCALS to restore TABLE to its original
1040 state, stopping when there are LIMIT entries left in LOCALs. */
1043 restore_nonzero_vars_to_original_value (void)
1045 while (VEC_length (tree, nonzero_vars_stack) > 0)
1047 tree name = VEC_pop (tree, nonzero_vars_stack);
1052 bitmap_clear_bit (nonzero_vars, SSA_NAME_VERSION (name));
1056 /* Use the source/dest pairs in CONST_AND_COPIES_STACK to restore
1057 CONST_AND_COPIES to its original state, stopping when we hit a
1061 restore_vars_to_original_value (void)
1063 while (VEC_length (tree, const_and_copies_stack) > 0)
1065 tree prev_value, dest;
1067 dest = VEC_pop (tree, const_and_copies_stack);
1072 prev_value = VEC_pop (tree, const_and_copies_stack);
1073 SSA_NAME_VALUE (dest) = prev_value;
1077 /* We have finished processing the dominator children of BB, perform
1078 any finalization actions in preparation for leaving this node in
1079 the dominator tree. */
1082 dom_opt_finalize_block (struct dom_walk_data *walk_data, basic_block bb)
1086 /* If we have an outgoing edge to a block with multiple incoming and
1087 outgoing edges, then we may be able to thread the edge. ie, we
1088 may be able to statically determine which of the outgoing edges
1089 will be traversed when the incoming edge from BB is traversed. */
1090 if (single_succ_p (bb)
1091 && (single_succ_edge (bb)->flags & EDGE_ABNORMAL) == 0
1092 && !single_pred_p (single_succ (bb))
1093 && !single_succ_p (single_succ (bb)))
1096 thread_across_edge (walk_data, single_succ_edge (bb));
1098 else if ((last = last_stmt (bb))
1099 && TREE_CODE (last) == COND_EXPR
1100 && (COMPARISON_CLASS_P (COND_EXPR_COND (last))
1101 || TREE_CODE (COND_EXPR_COND (last)) == SSA_NAME)
1102 && EDGE_COUNT (bb->succs) == 2
1103 && (EDGE_SUCC (bb, 0)->flags & EDGE_ABNORMAL) == 0
1104 && (EDGE_SUCC (bb, 1)->flags & EDGE_ABNORMAL) == 0)
1106 edge true_edge, false_edge;
1108 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
1110 /* Only try to thread the edge if it reaches a target block with
1111 more than one predecessor and more than one successor. */
1112 if (!single_pred_p (true_edge->dest) && !single_succ_p (true_edge->dest))
1114 struct edge_info *edge_info;
1117 /* Push a marker onto the available expression stack so that we
1118 unwind any expressions related to the TRUE arm before processing
1119 the false arm below. */
1120 VEC_safe_push (tree, heap, avail_exprs_stack, NULL_TREE);
1121 VEC_safe_push (tree, heap, const_and_copies_stack, NULL_TREE);
1123 edge_info = true_edge->aux;
1125 /* If we have info associated with this edge, record it into
1126 our equivalency tables. */
1129 tree *cond_equivalences = edge_info->cond_equivalences;
1130 tree lhs = edge_info->lhs;
1131 tree rhs = edge_info->rhs;
1133 /* If we have a simple NAME = VALUE equivalency record it. */
1134 if (lhs && TREE_CODE (lhs) == SSA_NAME)
1135 record_const_or_copy (lhs, rhs);
1137 /* If we have 0 = COND or 1 = COND equivalences, record them
1138 into our expression hash tables. */
1139 if (cond_equivalences)
1140 for (i = 0; i < edge_info->max_cond_equivalences; i += 2)
1142 tree expr = cond_equivalences[i];
1143 tree value = cond_equivalences[i + 1];
1145 record_cond (expr, value);
1149 /* Now thread the edge. */
1150 thread_across_edge (walk_data, true_edge);
1152 /* And restore the various tables to their state before
1153 we threaded this edge. */
1154 remove_local_expressions_from_table ();
1155 restore_vars_to_original_value ();
1158 /* Similarly for the ELSE arm. */
1159 if (!single_pred_p (false_edge->dest) && !single_succ_p (false_edge->dest))
1161 struct edge_info *edge_info;
1164 edge_info = false_edge->aux;
1166 /* If we have info associated with this edge, record it into
1167 our equivalency tables. */
1170 tree *cond_equivalences = edge_info->cond_equivalences;
1171 tree lhs = edge_info->lhs;
1172 tree rhs = edge_info->rhs;
1174 /* If we have a simple NAME = VALUE equivalency record it. */
1175 if (lhs && TREE_CODE (lhs) == SSA_NAME)
1176 record_const_or_copy (lhs, rhs);
1178 /* If we have 0 = COND or 1 = COND equivalences, record them
1179 into our expression hash tables. */
1180 if (cond_equivalences)
1181 for (i = 0; i < edge_info->max_cond_equivalences; i += 2)
1183 tree expr = cond_equivalences[i];
1184 tree value = cond_equivalences[i + 1];
1186 record_cond (expr, value);
1190 thread_across_edge (walk_data, false_edge);
1192 /* No need to remove local expressions from our tables
1193 or restore vars to their original value as that will
1194 be done immediately below. */
1198 remove_local_expressions_from_table ();
1199 restore_nonzero_vars_to_original_value ();
1200 restore_vars_to_original_value ();
1202 /* Remove VRP records associated with this basic block. They are no
1205 To be efficient, we note which variables have had their values
1206 constrained in this block. So walk over each variable in the
1207 VRP_VARIABLEs array. */
1208 while (VEC_length (tree, vrp_variables_stack) > 0)
1210 tree var = VEC_pop (tree, vrp_variables_stack);
1211 struct vrp_hash_elt vrp_hash_elt, *vrp_hash_elt_p;
1214 /* Each variable has a stack of value range records. We want to
1215 invalidate those associated with our basic block. So we walk
1216 the array backwards popping off records associated with our
1217 block. Once we hit a record not associated with our block
1219 VEC(vrp_element_p,heap) **var_vrp_records;
1224 vrp_hash_elt.var = var;
1225 vrp_hash_elt.records = NULL;
1227 slot = htab_find_slot (vrp_data, &vrp_hash_elt, NO_INSERT);
1229 vrp_hash_elt_p = (struct vrp_hash_elt *) *slot;
1230 var_vrp_records = &vrp_hash_elt_p->records;
1232 while (VEC_length (vrp_element_p, *var_vrp_records) > 0)
1234 struct vrp_element *element
1235 = VEC_last (vrp_element_p, *var_vrp_records);
1237 if (element->bb != bb)
1240 VEC_pop (vrp_element_p, *var_vrp_records);
1244 /* If we queued any statements to rescan in this block, then
1245 go ahead and rescan them now. */
1246 while (VEC_length (tree, stmts_to_rescan) > 0)
1248 tree stmt = VEC_last (tree, stmts_to_rescan);
1249 basic_block stmt_bb = bb_for_stmt (stmt);
1254 VEC_pop (tree, stmts_to_rescan);
1255 mark_new_vars_to_rename (stmt);
1259 /* PHI nodes can create equivalences too.
1261 Ignoring any alternatives which are the same as the result, if
1262 all the alternatives are equal, then the PHI node creates an
1265 Additionally, if all the PHI alternatives are known to have a nonzero
1266 value, then the result of this PHI is known to have a nonzero value,
1267 even if we do not know its exact value. */
1270 record_equivalences_from_phis (basic_block bb)
1274 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
1276 tree lhs = PHI_RESULT (phi);
1280 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
1282 tree t = PHI_ARG_DEF (phi, i);
1284 /* Ignore alternatives which are the same as our LHS. Since
1285 LHS is a PHI_RESULT, it is known to be a SSA_NAME, so we
1286 can simply compare pointers. */
1290 /* If we have not processed an alternative yet, then set
1291 RHS to this alternative. */
1294 /* If we have processed an alternative (stored in RHS), then
1295 see if it is equal to this one. If it isn't, then stop
1297 else if (! operand_equal_for_phi_arg_p (rhs, t))
1301 /* If we had no interesting alternatives, then all the RHS alternatives
1302 must have been the same as LHS. */
1306 /* If we managed to iterate through each PHI alternative without
1307 breaking out of the loop, then we have a PHI which may create
1308 a useful equivalence. We do not need to record unwind data for
1309 this, since this is a true assignment and not an equivalence
1310 inferred from a comparison. All uses of this ssa name are dominated
1311 by this assignment, so unwinding just costs time and space. */
1312 if (i == PHI_NUM_ARGS (phi)
1313 && may_propagate_copy (lhs, rhs))
1314 SSA_NAME_VALUE (lhs) = rhs;
1316 /* Now see if we know anything about the nonzero property for the
1317 result of this PHI. */
1318 for (i = 0; i < PHI_NUM_ARGS (phi); i++)
1320 if (!PHI_ARG_NONZERO (phi, i))
1324 if (i == PHI_NUM_ARGS (phi))
1325 bitmap_set_bit (nonzero_vars, SSA_NAME_VERSION (PHI_RESULT (phi)));
1329 /* Ignoring loop backedges, if BB has precisely one incoming edge then
1330 return that edge. Otherwise return NULL. */
1332 single_incoming_edge_ignoring_loop_edges (basic_block bb)
1338 FOR_EACH_EDGE (e, ei, bb->preds)
1340 /* A loop back edge can be identified by the destination of
1341 the edge dominating the source of the edge. */
1342 if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest))
1345 /* If we have already seen a non-loop edge, then we must have
1346 multiple incoming non-loop edges and thus we return NULL. */
1350 /* This is the first non-loop incoming edge we have found. Record
1358 /* Record any equivalences created by the incoming edge to BB. If BB
1359 has more than one incoming edge, then no equivalence is created. */
1362 record_equivalences_from_incoming_edge (basic_block bb)
1366 struct edge_info *edge_info;
1368 /* If our parent block ended with a control statement, then we may be
1369 able to record some equivalences based on which outgoing edge from
1370 the parent was followed. */
1371 parent = get_immediate_dominator (CDI_DOMINATORS, bb);
1373 e = single_incoming_edge_ignoring_loop_edges (bb);
1375 /* If we had a single incoming edge from our parent block, then enter
1376 any data associated with the edge into our tables. */
1377 if (e && e->src == parent)
1385 tree lhs = edge_info->lhs;
1386 tree rhs = edge_info->rhs;
1387 tree *cond_equivalences = edge_info->cond_equivalences;
1390 record_equality (lhs, rhs);
1392 if (cond_equivalences)
1394 bool recorded_range = false;
1395 for (i = 0; i < edge_info->max_cond_equivalences; i += 2)
1397 tree expr = cond_equivalences[i];
1398 tree value = cond_equivalences[i + 1];
1400 record_cond (expr, value);
1402 /* For the first true equivalence, record range
1403 information. We only do this for the first
1404 true equivalence as it should dominate any
1405 later true equivalences. */
1406 if (! recorded_range
1407 && COMPARISON_CLASS_P (expr)
1408 && value == boolean_true_node
1409 && TREE_CONSTANT (TREE_OPERAND (expr, 1)))
1411 record_range (expr, bb);
1412 recorded_range = true;
1420 /* Dump SSA statistics on FILE. */
1423 dump_dominator_optimization_stats (FILE *file)
1427 fprintf (file, "Total number of statements: %6ld\n\n",
1428 opt_stats.num_stmts);
1429 fprintf (file, "Exprs considered for dominator optimizations: %6ld\n",
1430 opt_stats.num_exprs_considered);
1432 n_exprs = opt_stats.num_exprs_considered;
1436 fprintf (file, " Redundant expressions eliminated: %6ld (%.0f%%)\n",
1437 opt_stats.num_re, PERCENT (opt_stats.num_re,
1439 fprintf (file, " Constants propagated: %6ld\n",
1440 opt_stats.num_const_prop);
1441 fprintf (file, " Copies propagated: %6ld\n",
1442 opt_stats.num_copy_prop);
1444 fprintf (file, "\nTotal number of DOM iterations: %6ld\n",
1445 opt_stats.num_iterations);
1447 fprintf (file, "\nHash table statistics:\n");
1449 fprintf (file, " avail_exprs: ");
1450 htab_statistics (file, avail_exprs);
1454 /* Dump SSA statistics on stderr. */
1457 debug_dominator_optimization_stats (void)
1459 dump_dominator_optimization_stats (stderr);
1463 /* Dump statistics for the hash table HTAB. */
1466 htab_statistics (FILE *file, htab_t htab)
1468 fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n",
1469 (long) htab_size (htab),
1470 (long) htab_elements (htab),
1471 htab_collisions (htab));
1474 /* Record the fact that VAR has a nonzero value, though we may not know
1475 its exact value. Note that if VAR is already known to have a nonzero
1476 value, then we do nothing. */
1479 record_var_is_nonzero (tree var)
1481 int indx = SSA_NAME_VERSION (var);
1483 if (bitmap_bit_p (nonzero_vars, indx))
1486 /* Mark it in the global table. */
1487 bitmap_set_bit (nonzero_vars, indx);
1489 /* Record this SSA_NAME so that we can reset the global table
1490 when we leave this block. */
1491 VEC_safe_push (tree, heap, nonzero_vars_stack, var);
1494 /* Enter a statement into the true/false expression hash table indicating
1495 that the condition COND has the value VALUE. */
1498 record_cond (tree cond, tree value)
1500 struct expr_hash_elt *element = xmalloc (sizeof (struct expr_hash_elt));
1503 initialize_hash_element (cond, value, element);
1505 slot = htab_find_slot_with_hash (avail_exprs, (void *)element,
1506 element->hash, INSERT);
1509 *slot = (void *) element;
1510 VEC_safe_push (tree, heap, avail_exprs_stack, cond);
1516 /* Build a new conditional using NEW_CODE, OP0 and OP1 and store
1517 the new conditional into *p, then store a boolean_true_node
1521 build_and_record_new_cond (enum tree_code new_code, tree op0, tree op1, tree *p)
1523 *p = build2 (new_code, boolean_type_node, op0, op1);
1525 *p = boolean_true_node;
1528 /* Record that COND is true and INVERTED is false into the edge information
1529 structure. Also record that any conditions dominated by COND are true
1532 For example, if a < b is true, then a <= b must also be true. */
1535 record_conditions (struct edge_info *edge_info, tree cond, tree inverted)
1539 if (!COMPARISON_CLASS_P (cond))
1542 op0 = TREE_OPERAND (cond, 0);
1543 op1 = TREE_OPERAND (cond, 1);
1545 switch (TREE_CODE (cond))
1549 edge_info->max_cond_equivalences = 12;
1550 edge_info->cond_equivalences = xmalloc (12 * sizeof (tree));
1551 build_and_record_new_cond ((TREE_CODE (cond) == LT_EXPR
1552 ? LE_EXPR : GE_EXPR),
1553 op0, op1, &edge_info->cond_equivalences[4]);
1554 build_and_record_new_cond (ORDERED_EXPR, op0, op1,
1555 &edge_info->cond_equivalences[6]);
1556 build_and_record_new_cond (NE_EXPR, op0, op1,
1557 &edge_info->cond_equivalences[8]);
1558 build_and_record_new_cond (LTGT_EXPR, op0, op1,
1559 &edge_info->cond_equivalences[10]);
1564 edge_info->max_cond_equivalences = 6;
1565 edge_info->cond_equivalences = xmalloc (6 * sizeof (tree));
1566 build_and_record_new_cond (ORDERED_EXPR, op0, op1,
1567 &edge_info->cond_equivalences[4]);
1571 edge_info->max_cond_equivalences = 10;
1572 edge_info->cond_equivalences = xmalloc (10 * sizeof (tree));
1573 build_and_record_new_cond (ORDERED_EXPR, op0, op1,
1574 &edge_info->cond_equivalences[4]);
1575 build_and_record_new_cond (LE_EXPR, op0, op1,
1576 &edge_info->cond_equivalences[6]);
1577 build_and_record_new_cond (GE_EXPR, op0, op1,
1578 &edge_info->cond_equivalences[8]);
1581 case UNORDERED_EXPR:
1582 edge_info->max_cond_equivalences = 16;
1583 edge_info->cond_equivalences = xmalloc (16 * sizeof (tree));
1584 build_and_record_new_cond (NE_EXPR, op0, op1,
1585 &edge_info->cond_equivalences[4]);
1586 build_and_record_new_cond (UNLE_EXPR, op0, op1,
1587 &edge_info->cond_equivalences[6]);
1588 build_and_record_new_cond (UNGE_EXPR, op0, op1,
1589 &edge_info->cond_equivalences[8]);
1590 build_and_record_new_cond (UNEQ_EXPR, op0, op1,
1591 &edge_info->cond_equivalences[10]);
1592 build_and_record_new_cond (UNLT_EXPR, op0, op1,
1593 &edge_info->cond_equivalences[12]);
1594 build_and_record_new_cond (UNGT_EXPR, op0, op1,
1595 &edge_info->cond_equivalences[14]);
1600 edge_info->max_cond_equivalences = 8;
1601 edge_info->cond_equivalences = xmalloc (8 * sizeof (tree));
1602 build_and_record_new_cond ((TREE_CODE (cond) == UNLT_EXPR
1603 ? UNLE_EXPR : UNGE_EXPR),
1604 op0, op1, &edge_info->cond_equivalences[4]);
1605 build_and_record_new_cond (NE_EXPR, op0, op1,
1606 &edge_info->cond_equivalences[6]);
1610 edge_info->max_cond_equivalences = 8;
1611 edge_info->cond_equivalences = xmalloc (8 * sizeof (tree));
1612 build_and_record_new_cond (UNLE_EXPR, op0, op1,
1613 &edge_info->cond_equivalences[4]);
1614 build_and_record_new_cond (UNGE_EXPR, op0, op1,
1615 &edge_info->cond_equivalences[6]);
1619 edge_info->max_cond_equivalences = 8;
1620 edge_info->cond_equivalences = xmalloc (8 * sizeof (tree));
1621 build_and_record_new_cond (NE_EXPR, op0, op1,
1622 &edge_info->cond_equivalences[4]);
1623 build_and_record_new_cond (ORDERED_EXPR, op0, op1,
1624 &edge_info->cond_equivalences[6]);
1628 edge_info->max_cond_equivalences = 4;
1629 edge_info->cond_equivalences = xmalloc (4 * sizeof (tree));
1633 /* Now store the original true and false conditions into the first
1635 edge_info->cond_equivalences[0] = cond;
1636 edge_info->cond_equivalences[1] = boolean_true_node;
1637 edge_info->cond_equivalences[2] = inverted;
1638 edge_info->cond_equivalences[3] = boolean_false_node;
1641 /* A helper function for record_const_or_copy and record_equality.
1642 Do the work of recording the value and undo info. */
1645 record_const_or_copy_1 (tree x, tree y, tree prev_x)
1647 SSA_NAME_VALUE (x) = y;
1649 VEC_reserve (tree, heap, const_and_copies_stack, 2);
1650 VEC_quick_push (tree, const_and_copies_stack, prev_x);
1651 VEC_quick_push (tree, const_and_copies_stack, x);
1655 /* Return the loop depth of the basic block of the defining statement of X.
1656 This number should not be treated as absolutely correct because the loop
1657 information may not be completely up-to-date when dom runs. However, it
1658 will be relatively correct, and as more passes are taught to keep loop info
1659 up to date, the result will become more and more accurate. */
1662 loop_depth_of_name (tree x)
1667 /* If it's not an SSA_NAME, we have no clue where the definition is. */
1668 if (TREE_CODE (x) != SSA_NAME)
1671 /* Otherwise return the loop depth of the defining statement's bb.
1672 Note that there may not actually be a bb for this statement, if the
1673 ssa_name is live on entry. */
1674 defstmt = SSA_NAME_DEF_STMT (x);
1675 defbb = bb_for_stmt (defstmt);
1679 return defbb->loop_depth;
1683 /* Record that X is equal to Y in const_and_copies. Record undo
1684 information in the block-local vector. */
1687 record_const_or_copy (tree x, tree y)
1689 tree prev_x = SSA_NAME_VALUE (x);
1691 if (TREE_CODE (y) == SSA_NAME)
1693 tree tmp = SSA_NAME_VALUE (y);
1698 record_const_or_copy_1 (x, y, prev_x);
1701 /* Similarly, but assume that X and Y are the two operands of an EQ_EXPR.
1702 This constrains the cases in which we may treat this as assignment. */
1705 record_equality (tree x, tree y)
1707 tree prev_x = NULL, prev_y = NULL;
1709 if (TREE_CODE (x) == SSA_NAME)
1710 prev_x = SSA_NAME_VALUE (x);
1711 if (TREE_CODE (y) == SSA_NAME)
1712 prev_y = SSA_NAME_VALUE (y);
1714 /* If one of the previous values is invariant, or invariant in more loops
1715 (by depth), then use that.
1716 Otherwise it doesn't matter which value we choose, just so
1717 long as we canonicalize on one value. */
1718 if (TREE_INVARIANT (y))
1720 else if (TREE_INVARIANT (x) || (loop_depth_of_name (x) <= loop_depth_of_name (y)))
1721 prev_x = x, x = y, y = prev_x, prev_x = prev_y;
1722 else if (prev_x && TREE_INVARIANT (prev_x))
1723 x = y, y = prev_x, prev_x = prev_y;
1724 else if (prev_y && TREE_CODE (prev_y) != VALUE_HANDLE)
1727 /* After the swapping, we must have one SSA_NAME. */
1728 if (TREE_CODE (x) != SSA_NAME)
1731 /* For IEEE, -0.0 == 0.0, so we don't necessarily know the sign of a
1732 variable compared against zero. If we're honoring signed zeros,
1733 then we cannot record this value unless we know that the value is
1735 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (x)))
1736 && (TREE_CODE (y) != REAL_CST
1737 || REAL_VALUES_EQUAL (dconst0, TREE_REAL_CST (y))))
1740 record_const_or_copy_1 (x, y, prev_x);
1743 /* Return true, if it is ok to do folding of an associative expression.
1744 EXP is the tree for the associative expression. */
1747 unsafe_associative_fp_binop (tree exp)
1749 enum tree_code code = TREE_CODE (exp);
1750 return !(!flag_unsafe_math_optimizations
1751 && (code == MULT_EXPR || code == PLUS_EXPR
1752 || code == MINUS_EXPR)
1753 && FLOAT_TYPE_P (TREE_TYPE (exp)));
1756 /* Returns true when STMT is a simple iv increment. It detects the
1757 following situation:
1759 i_1 = phi (..., i_2)
1760 i_2 = i_1 +/- ... */
1763 simple_iv_increment_p (tree stmt)
1765 tree lhs, rhs, preinc, phi;
1768 if (TREE_CODE (stmt) != MODIFY_EXPR)
1771 lhs = TREE_OPERAND (stmt, 0);
1772 if (TREE_CODE (lhs) != SSA_NAME)
1775 rhs = TREE_OPERAND (stmt, 1);
1777 if (TREE_CODE (rhs) != PLUS_EXPR
1778 && TREE_CODE (rhs) != MINUS_EXPR)
1781 preinc = TREE_OPERAND (rhs, 0);
1782 if (TREE_CODE (preinc) != SSA_NAME)
1785 phi = SSA_NAME_DEF_STMT (preinc);
1786 if (TREE_CODE (phi) != PHI_NODE)
1789 for (i = 0; i < (unsigned) PHI_NUM_ARGS (phi); i++)
1790 if (PHI_ARG_DEF (phi, i) == lhs)
1796 /* COND is a condition of the form:
1798 x == const or x != const
1800 Look back to x's defining statement and see if x is defined as
1804 If const is unchanged if we convert it to type, then we can build
1805 the equivalent expression:
1808 y == const or y != const
1810 Which may allow further optimizations.
1812 Return the equivalent comparison or NULL if no such equivalent comparison
1816 find_equivalent_equality_comparison (tree cond)
1818 tree op0 = TREE_OPERAND (cond, 0);
1819 tree op1 = TREE_OPERAND (cond, 1);
1820 tree def_stmt = SSA_NAME_DEF_STMT (op0);
1822 /* OP0 might have been a parameter, so first make sure it
1823 was defined by a MODIFY_EXPR. */
1824 if (def_stmt && TREE_CODE (def_stmt) == MODIFY_EXPR)
1826 tree def_rhs = TREE_OPERAND (def_stmt, 1);
1829 /* If either operand to the comparison is a pointer to
1830 a function, then we can not apply this optimization
1831 as some targets require function pointers to be
1832 canonicalized and in this case this optimization would
1833 eliminate a necessary canonicalization. */
1834 if ((POINTER_TYPE_P (TREE_TYPE (op0))
1835 && TREE_CODE (TREE_TYPE (TREE_TYPE (op0))) == FUNCTION_TYPE)
1836 || (POINTER_TYPE_P (TREE_TYPE (op1))
1837 && TREE_CODE (TREE_TYPE (TREE_TYPE (op1))) == FUNCTION_TYPE))
1840 /* Now make sure the RHS of the MODIFY_EXPR is a typecast. */
1841 if ((TREE_CODE (def_rhs) == NOP_EXPR
1842 || TREE_CODE (def_rhs) == CONVERT_EXPR)
1843 && TREE_CODE (TREE_OPERAND (def_rhs, 0)) == SSA_NAME)
1845 tree def_rhs_inner = TREE_OPERAND (def_rhs, 0);
1846 tree def_rhs_inner_type = TREE_TYPE (def_rhs_inner);
1849 if (TYPE_PRECISION (def_rhs_inner_type)
1850 > TYPE_PRECISION (TREE_TYPE (def_rhs)))
1853 /* If the inner type of the conversion is a pointer to
1854 a function, then we can not apply this optimization
1855 as some targets require function pointers to be
1856 canonicalized. This optimization would result in
1857 canonicalization of the pointer when it was not originally
1859 if (POINTER_TYPE_P (def_rhs_inner_type)
1860 && TREE_CODE (TREE_TYPE (def_rhs_inner_type)) == FUNCTION_TYPE)
1863 /* What we want to prove is that if we convert OP1 to
1864 the type of the object inside the NOP_EXPR that the
1865 result is still equivalent to SRC.
1867 If that is true, the build and return new equivalent
1868 condition which uses the source of the typecast and the
1869 new constant (which has only changed its type). */
1870 new = build1 (TREE_CODE (def_rhs), def_rhs_inner_type, op1);
1871 new = local_fold (new);
1872 if (is_gimple_val (new) && tree_int_cst_equal (new, op1))
1873 return build2 (TREE_CODE (cond), TREE_TYPE (cond),
1874 def_rhs_inner, new);
1880 /* STMT is a COND_EXPR for which we could not trivially determine its
1881 result. This routine attempts to find equivalent forms of the
1882 condition which we may be able to optimize better. It also
1883 uses simple value range propagation to optimize conditionals. */
1886 simplify_cond_and_lookup_avail_expr (tree stmt,
1890 tree cond = COND_EXPR_COND (stmt);
1892 if (COMPARISON_CLASS_P (cond))
1894 tree op0 = TREE_OPERAND (cond, 0);
1895 tree op1 = TREE_OPERAND (cond, 1);
1897 if (TREE_CODE (op0) == SSA_NAME && is_gimple_min_invariant (op1))
1900 tree low, high, cond_low, cond_high;
1901 int lowequal, highequal, swapped, no_overlap, subset, cond_inverted;
1902 VEC(vrp_element_p,heap) **vrp_records;
1903 struct vrp_element *element;
1904 struct vrp_hash_elt vrp_hash_elt, *vrp_hash_elt_p;
1907 /* First see if we have test of an SSA_NAME against a constant
1908 where the SSA_NAME is defined by an earlier typecast which
1909 is irrelevant when performing tests against the given
1911 if (TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1913 tree new_cond = find_equivalent_equality_comparison (cond);
1917 /* Update the statement to use the new equivalent
1919 COND_EXPR_COND (stmt) = new_cond;
1921 /* If this is not a real stmt, ann will be NULL and we
1922 avoid processing the operands. */
1924 mark_stmt_modified (stmt);
1926 /* Lookup the condition and return its known value if it
1928 new_cond = lookup_avail_expr (stmt, insert);
1932 /* The operands have changed, so update op0 and op1. */
1933 op0 = TREE_OPERAND (cond, 0);
1934 op1 = TREE_OPERAND (cond, 1);
1938 /* Consult the value range records for this variable (if they exist)
1939 to see if we can eliminate or simplify this conditional.
1941 Note two tests are necessary to determine no records exist.
1942 First we have to see if the virtual array exists, if it
1943 exists, then we have to check its active size.
1945 Also note the vast majority of conditionals are not testing
1946 a variable which has had its range constrained by an earlier
1947 conditional. So this filter avoids a lot of unnecessary work. */
1948 vrp_hash_elt.var = op0;
1949 vrp_hash_elt.records = NULL;
1950 slot = htab_find_slot (vrp_data, &vrp_hash_elt, NO_INSERT);
1954 vrp_hash_elt_p = (struct vrp_hash_elt *) *slot;
1955 vrp_records = &vrp_hash_elt_p->records;
1957 limit = VEC_length (vrp_element_p, *vrp_records);
1959 /* If we have no value range records for this variable, or we are
1960 unable to extract a range for this condition, then there is
1963 || ! extract_range_from_cond (cond, &cond_high,
1964 &cond_low, &cond_inverted))
1967 /* We really want to avoid unnecessary computations of range
1968 info. So all ranges are computed lazily; this avoids a
1969 lot of unnecessary work. i.e., we record the conditional,
1970 but do not process how it constrains the variable's
1971 potential values until we know that processing the condition
1974 However, we do not want to have to walk a potentially long
1975 list of ranges, nor do we want to compute a variable's
1976 range more than once for a given path.
1978 Luckily, each time we encounter a conditional that can not
1979 be otherwise optimized we will end up here and we will
1980 compute the necessary range information for the variable
1981 used in this condition.
1983 Thus you can conclude that there will never be more than one
1984 conditional associated with a variable which has not been
1985 processed. So we never need to merge more than one new
1986 conditional into the current range.
1988 These properties also help us avoid unnecessary work. */
1989 element = VEC_last (vrp_element_p, *vrp_records);
1991 if (element->high && element->low)
1993 /* The last element has been processed, so there is no range
1994 merging to do, we can simply use the high/low values
1995 recorded in the last element. */
1997 high = element->high;
2001 tree tmp_high, tmp_low;
2004 /* The last element has not been processed. Process it now.
2005 record_range should ensure for cond inverted is not set.
2006 This call can only fail if cond is x < min or x > max,
2007 which fold should have optimized into false.
2008 If that doesn't happen, just pretend all values are
2010 if (! extract_range_from_cond (element->cond, &tmp_high,
2014 gcc_assert (dummy == 0);
2016 /* If this is the only element, then no merging is necessary,
2017 the high/low values from extract_range_from_cond are all
2026 /* Get the high/low value from the previous element. */
2027 struct vrp_element *prev
2028 = VEC_index (vrp_element_p, *vrp_records, limit - 2);
2032 /* Merge in this element's range with the range from the
2035 The low value for the merged range is the maximum of
2036 the previous low value and the low value of this record.
2038 Similarly the high value for the merged range is the
2039 minimum of the previous high value and the high value of
2041 low = (low && tree_int_cst_compare (low, tmp_low) == 1
2043 high = (high && tree_int_cst_compare (high, tmp_high) == -1
2047 /* And record the computed range. */
2049 element->high = high;
2053 /* After we have constrained this variable's potential values,
2054 we try to determine the result of the given conditional.
2056 To simplify later tests, first determine if the current
2057 low value is the same low value as the conditional.
2058 Similarly for the current high value and the high value
2059 for the conditional. */
2060 lowequal = tree_int_cst_equal (low, cond_low);
2061 highequal = tree_int_cst_equal (high, cond_high);
2063 if (lowequal && highequal)
2064 return (cond_inverted ? boolean_false_node : boolean_true_node);
2066 /* To simplify the overlap/subset tests below we may want
2067 to swap the two ranges so that the larger of the two
2068 ranges occurs "first". */
2070 if (tree_int_cst_compare (low, cond_low) == 1
2072 && tree_int_cst_compare (cond_high, high) == 1))
2085 /* Now determine if there is no overlap in the ranges
2086 or if the second range is a subset of the first range. */
2087 no_overlap = tree_int_cst_lt (high, cond_low);
2088 subset = tree_int_cst_compare (cond_high, high) != 1;
2090 /* If there was no overlap in the ranges, then this conditional
2091 always has a false value (unless we had to invert this
2092 conditional, in which case it always has a true value). */
2094 return (cond_inverted ? boolean_true_node : boolean_false_node);
2096 /* If the current range is a subset of the condition's range,
2097 then this conditional always has a true value (unless we
2098 had to invert this conditional, in which case it always
2099 has a true value). */
2100 if (subset && swapped)
2101 return (cond_inverted ? boolean_false_node : boolean_true_node);
2103 /* We were unable to determine the result of the conditional.
2104 However, we may be able to simplify the conditional. First
2105 merge the ranges in the same manner as range merging above. */
2106 low = tree_int_cst_compare (low, cond_low) == 1 ? low : cond_low;
2107 high = tree_int_cst_compare (high, cond_high) == -1 ? high : cond_high;
2109 /* If the range has converged to a single point, then turn this
2110 into an equality comparison. */
2111 if (TREE_CODE (cond) != EQ_EXPR
2112 && TREE_CODE (cond) != NE_EXPR
2113 && tree_int_cst_equal (low, high))
2115 TREE_SET_CODE (cond, EQ_EXPR);
2116 TREE_OPERAND (cond, 1) = high;
2123 /* STMT is a SWITCH_EXPR for which we could not trivially determine its
2124 result. This routine attempts to find equivalent forms of the
2125 condition which we may be able to optimize better. */
2128 simplify_switch_and_lookup_avail_expr (tree stmt, int insert)
2130 tree cond = SWITCH_COND (stmt);
2133 /* The optimization that we really care about is removing unnecessary
2134 casts. That will let us do much better in propagating the inferred
2135 constant at the switch target. */
2136 if (TREE_CODE (cond) == SSA_NAME)
2138 def = SSA_NAME_DEF_STMT (cond);
2139 if (TREE_CODE (def) == MODIFY_EXPR)
2141 def = TREE_OPERAND (def, 1);
2142 if (TREE_CODE (def) == NOP_EXPR)
2147 def = TREE_OPERAND (def, 0);
2149 #ifdef ENABLE_CHECKING
2150 /* ??? Why was Jeff testing this? We are gimple... */
2151 gcc_assert (is_gimple_val (def));
2154 to = TREE_TYPE (cond);
2155 ti = TREE_TYPE (def);
2157 /* If we have an extension that preserves value, then we
2158 can copy the source value into the switch. */
2160 need_precision = TYPE_PRECISION (ti);
2162 if (TYPE_UNSIGNED (to) && !TYPE_UNSIGNED (ti))
2164 else if (!TYPE_UNSIGNED (to) && TYPE_UNSIGNED (ti))
2165 need_precision += 1;
2166 if (TYPE_PRECISION (to) < need_precision)
2171 SWITCH_COND (stmt) = def;
2172 mark_stmt_modified (stmt);
2174 return lookup_avail_expr (stmt, insert);
2184 /* CONST_AND_COPIES is a table which maps an SSA_NAME to the current
2185 known value for that SSA_NAME (or NULL if no value is known).
2187 NONZERO_VARS is the set SSA_NAMES known to have a nonzero value,
2188 even if we don't know their precise value.
2190 Propagate values from CONST_AND_COPIES and NONZERO_VARS into the PHI
2191 nodes of the successors of BB. */
2194 cprop_into_successor_phis (basic_block bb, bitmap nonzero_vars)
2199 FOR_EACH_EDGE (e, ei, bb->succs)
2204 /* If this is an abnormal edge, then we do not want to copy propagate
2205 into the PHI alternative associated with this edge. */
2206 if (e->flags & EDGE_ABNORMAL)
2209 phi = phi_nodes (e->dest);
2214 for ( ; phi; phi = PHI_CHAIN (phi))
2217 use_operand_p orig_p;
2220 /* The alternative may be associated with a constant, so verify
2221 it is an SSA_NAME before doing anything with it. */
2222 orig_p = PHI_ARG_DEF_PTR (phi, indx);
2223 orig = USE_FROM_PTR (orig_p);
2224 if (TREE_CODE (orig) != SSA_NAME)
2227 /* If the alternative is known to have a nonzero value, record
2228 that fact in the PHI node itself for future use. */
2229 if (bitmap_bit_p (nonzero_vars, SSA_NAME_VERSION (orig)))
2230 PHI_ARG_NONZERO (phi, indx) = true;
2232 /* If we have *ORIG_P in our constant/copy table, then replace
2233 ORIG_P with its value in our constant/copy table. */
2234 new = SSA_NAME_VALUE (orig);
2237 && (TREE_CODE (new) == SSA_NAME
2238 || is_gimple_min_invariant (new))
2239 && may_propagate_copy (orig, new))
2240 propagate_value (orig_p, new);
2245 /* We have finished optimizing BB, record any information implied by
2246 taking a specific outgoing edge from BB. */
2249 record_edge_info (basic_block bb)
2251 block_stmt_iterator bsi = bsi_last (bb);
2252 struct edge_info *edge_info;
2254 if (! bsi_end_p (bsi))
2256 tree stmt = bsi_stmt (bsi);
2258 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
2260 tree cond = SWITCH_COND (stmt);
2262 if (TREE_CODE (cond) == SSA_NAME)
2264 tree labels = SWITCH_LABELS (stmt);
2265 int i, n_labels = TREE_VEC_LENGTH (labels);
2266 tree *info = xcalloc (last_basic_block, sizeof (tree));
2270 for (i = 0; i < n_labels; i++)
2272 tree label = TREE_VEC_ELT (labels, i);
2273 basic_block target_bb = label_to_block (CASE_LABEL (label));
2275 if (CASE_HIGH (label)
2276 || !CASE_LOW (label)
2277 || info[target_bb->index])
2278 info[target_bb->index] = error_mark_node;
2280 info[target_bb->index] = label;
2283 FOR_EACH_EDGE (e, ei, bb->succs)
2285 basic_block target_bb = e->dest;
2286 tree node = info[target_bb->index];
2288 if (node != NULL && node != error_mark_node)
2290 tree x = fold_convert (TREE_TYPE (cond), CASE_LOW (node));
2291 edge_info = allocate_edge_info (e);
2292 edge_info->lhs = cond;
2300 /* A COND_EXPR may create equivalences too. */
2301 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2303 tree cond = COND_EXPR_COND (stmt);
2307 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2309 /* If the conditional is a single variable 'X', record 'X = 1'
2310 for the true edge and 'X = 0' on the false edge. */
2311 if (SSA_VAR_P (cond))
2313 struct edge_info *edge_info;
2315 edge_info = allocate_edge_info (true_edge);
2316 edge_info->lhs = cond;
2317 edge_info->rhs = constant_boolean_node (1, TREE_TYPE (cond));
2319 edge_info = allocate_edge_info (false_edge);
2320 edge_info->lhs = cond;
2321 edge_info->rhs = constant_boolean_node (0, TREE_TYPE (cond));
2323 /* Equality tests may create one or two equivalences. */
2324 else if (COMPARISON_CLASS_P (cond))
2326 tree op0 = TREE_OPERAND (cond, 0);
2327 tree op1 = TREE_OPERAND (cond, 1);
2329 /* Special case comparing booleans against a constant as we
2330 know the value of OP0 on both arms of the branch. i.e., we
2331 can record an equivalence for OP0 rather than COND. */
2332 if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
2333 && TREE_CODE (op0) == SSA_NAME
2334 && TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE
2335 && is_gimple_min_invariant (op1))
2337 if (TREE_CODE (cond) == EQ_EXPR)
2339 edge_info = allocate_edge_info (true_edge);
2340 edge_info->lhs = op0;
2341 edge_info->rhs = (integer_zerop (op1)
2342 ? boolean_false_node
2343 : boolean_true_node);
2345 edge_info = allocate_edge_info (false_edge);
2346 edge_info->lhs = op0;
2347 edge_info->rhs = (integer_zerop (op1)
2349 : boolean_false_node);
2353 edge_info = allocate_edge_info (true_edge);
2354 edge_info->lhs = op0;
2355 edge_info->rhs = (integer_zerop (op1)
2357 : boolean_false_node);
2359 edge_info = allocate_edge_info (false_edge);
2360 edge_info->lhs = op0;
2361 edge_info->rhs = (integer_zerop (op1)
2362 ? boolean_false_node
2363 : boolean_true_node);
2367 else if (is_gimple_min_invariant (op0)
2368 && (TREE_CODE (op1) == SSA_NAME
2369 || is_gimple_min_invariant (op1)))
2371 tree inverted = invert_truthvalue (cond);
2372 struct edge_info *edge_info;
2374 edge_info = allocate_edge_info (true_edge);
2375 record_conditions (edge_info, cond, inverted);
2377 if (TREE_CODE (cond) == EQ_EXPR)
2379 edge_info->lhs = op1;
2380 edge_info->rhs = op0;
2383 edge_info = allocate_edge_info (false_edge);
2384 record_conditions (edge_info, inverted, cond);
2386 if (TREE_CODE (cond) == NE_EXPR)
2388 edge_info->lhs = op1;
2389 edge_info->rhs = op0;
2393 else if (TREE_CODE (op0) == SSA_NAME
2394 && (is_gimple_min_invariant (op1)
2395 || TREE_CODE (op1) == SSA_NAME))
2397 tree inverted = invert_truthvalue (cond);
2398 struct edge_info *edge_info;
2400 edge_info = allocate_edge_info (true_edge);
2401 record_conditions (edge_info, cond, inverted);
2403 if (TREE_CODE (cond) == EQ_EXPR)
2405 edge_info->lhs = op0;
2406 edge_info->rhs = op1;
2409 edge_info = allocate_edge_info (false_edge);
2410 record_conditions (edge_info, inverted, cond);
2412 if (TREE_CODE (cond) == NE_EXPR)
2414 edge_info->lhs = op0;
2415 edge_info->rhs = op1;
2420 /* ??? TRUTH_NOT_EXPR can create an equivalence too. */
2425 /* Propagate information from BB to its outgoing edges.
2427 This can include equivalency information implied by control statements
2428 at the end of BB and const/copy propagation into PHIs in BB's
2429 successor blocks. */
2432 propagate_to_outgoing_edges (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
2435 record_edge_info (bb);
2436 cprop_into_successor_phis (bb, nonzero_vars);
2439 /* Search for redundant computations in STMT. If any are found, then
2440 replace them with the variable holding the result of the computation.
2442 If safe, record this expression into the available expression hash
2446 eliminate_redundant_computations (tree stmt, stmt_ann_t ann)
2448 tree *expr_p, def = NULL_TREE;
2451 bool retval = false;
2452 bool modify_expr_p = false;
2454 if (TREE_CODE (stmt) == MODIFY_EXPR)
2455 def = TREE_OPERAND (stmt, 0);
2457 /* Certain expressions on the RHS can be optimized away, but can not
2458 themselves be entered into the hash tables. */
2459 if (ann->makes_aliased_stores
2461 || TREE_CODE (def) != SSA_NAME
2462 || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (def)
2463 || !ZERO_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF)
2464 /* Do not record equivalences for increments of ivs. This would create
2465 overlapping live ranges for a very questionable gain. */
2466 || simple_iv_increment_p (stmt))
2469 /* Check if the expression has been computed before. */
2470 cached_lhs = lookup_avail_expr (stmt, insert);
2472 /* If this is a COND_EXPR and we did not find its expression in
2473 the hash table, simplify the condition and try again. */
2474 if (! cached_lhs && TREE_CODE (stmt) == COND_EXPR)
2475 cached_lhs = simplify_cond_and_lookup_avail_expr (stmt, ann, insert);
2476 /* Similarly for a SWITCH_EXPR. */
2477 else if (!cached_lhs && TREE_CODE (stmt) == SWITCH_EXPR)
2478 cached_lhs = simplify_switch_and_lookup_avail_expr (stmt, insert);
2480 opt_stats.num_exprs_considered++;
2482 /* Get a pointer to the expression we are trying to optimize. */
2483 if (TREE_CODE (stmt) == COND_EXPR)
2484 expr_p = &COND_EXPR_COND (stmt);
2485 else if (TREE_CODE (stmt) == SWITCH_EXPR)
2486 expr_p = &SWITCH_COND (stmt);
2487 else if (TREE_CODE (stmt) == RETURN_EXPR && TREE_OPERAND (stmt, 0))
2489 expr_p = &TREE_OPERAND (TREE_OPERAND (stmt, 0), 1);
2490 modify_expr_p = true;
2494 expr_p = &TREE_OPERAND (stmt, 1);
2495 modify_expr_p = true;
2498 /* It is safe to ignore types here since we have already done
2499 type checking in the hashing and equality routines. In fact
2500 type checking here merely gets in the way of constant
2501 propagation. Also, make sure that it is safe to propagate
2502 CACHED_LHS into *EXPR_P. */
2504 && ((TREE_CODE (cached_lhs) != SSA_NAME
2506 || tree_ssa_useless_type_conversion_1 (TREE_TYPE (*expr_p),
2507 TREE_TYPE (cached_lhs))))
2508 || may_propagate_copy (*expr_p, cached_lhs)))
2510 if (dump_file && (dump_flags & TDF_DETAILS))
2512 fprintf (dump_file, " Replaced redundant expr '");
2513 print_generic_expr (dump_file, *expr_p, dump_flags);
2514 fprintf (dump_file, "' with '");
2515 print_generic_expr (dump_file, cached_lhs, dump_flags);
2516 fprintf (dump_file, "'\n");
2521 #if defined ENABLE_CHECKING
2522 gcc_assert (TREE_CODE (cached_lhs) == SSA_NAME
2523 || is_gimple_min_invariant (cached_lhs));
2526 if (TREE_CODE (cached_lhs) == ADDR_EXPR
2527 || (POINTER_TYPE_P (TREE_TYPE (*expr_p))
2528 && is_gimple_min_invariant (cached_lhs)))
2532 && !tree_ssa_useless_type_conversion_1 (TREE_TYPE (*expr_p),
2533 TREE_TYPE (cached_lhs)))
2534 cached_lhs = fold_convert (TREE_TYPE (*expr_p), cached_lhs);
2536 propagate_tree_value (expr_p, cached_lhs);
2537 mark_stmt_modified (stmt);
2542 /* STMT, a MODIFY_EXPR, may create certain equivalences, in either
2543 the available expressions table or the const_and_copies table.
2544 Detect and record those equivalences. */
2547 record_equivalences_from_stmt (tree stmt,
2551 tree lhs = TREE_OPERAND (stmt, 0);
2552 enum tree_code lhs_code = TREE_CODE (lhs);
2555 if (lhs_code == SSA_NAME)
2557 tree rhs = TREE_OPERAND (stmt, 1);
2559 /* Strip away any useless type conversions. */
2560 STRIP_USELESS_TYPE_CONVERSION (rhs);
2562 /* If the RHS of the assignment is a constant or another variable that
2563 may be propagated, register it in the CONST_AND_COPIES table. We
2564 do not need to record unwind data for this, since this is a true
2565 assignment and not an equivalence inferred from a comparison. All
2566 uses of this ssa name are dominated by this assignment, so unwinding
2567 just costs time and space. */
2569 && (TREE_CODE (rhs) == SSA_NAME
2570 || is_gimple_min_invariant (rhs)))
2571 SSA_NAME_VALUE (lhs) = rhs;
2573 if (tree_expr_nonzero_p (rhs))
2574 record_var_is_nonzero (lhs);
2577 /* Look at both sides for pointer dereferences. If we find one, then
2578 the pointer must be nonnull and we can enter that equivalence into
2580 if (flag_delete_null_pointer_checks)
2581 for (i = 0; i < 2; i++)
2583 tree t = TREE_OPERAND (stmt, i);
2585 /* Strip away any COMPONENT_REFs. */
2586 while (TREE_CODE (t) == COMPONENT_REF)
2587 t = TREE_OPERAND (t, 0);
2589 /* Now see if this is a pointer dereference. */
2590 if (INDIRECT_REF_P (t))
2592 tree op = TREE_OPERAND (t, 0);
2594 /* If the pointer is a SSA variable, then enter new
2595 equivalences into the hash table. */
2596 while (TREE_CODE (op) == SSA_NAME)
2598 tree def = SSA_NAME_DEF_STMT (op);
2600 record_var_is_nonzero (op);
2602 /* And walk up the USE-DEF chains noting other SSA_NAMEs
2603 which are known to have a nonzero value. */
2605 && TREE_CODE (def) == MODIFY_EXPR
2606 && TREE_CODE (TREE_OPERAND (def, 1)) == NOP_EXPR)
2607 op = TREE_OPERAND (TREE_OPERAND (def, 1), 0);
2614 /* A memory store, even an aliased store, creates a useful
2615 equivalence. By exchanging the LHS and RHS, creating suitable
2616 vops and recording the result in the available expression table,
2617 we may be able to expose more redundant loads. */
2618 if (!ann->has_volatile_ops
2619 && (TREE_CODE (TREE_OPERAND (stmt, 1)) == SSA_NAME
2620 || is_gimple_min_invariant (TREE_OPERAND (stmt, 1)))
2621 && !is_gimple_reg (lhs))
2623 tree rhs = TREE_OPERAND (stmt, 1);
2626 /* FIXME: If the LHS of the assignment is a bitfield and the RHS
2627 is a constant, we need to adjust the constant to fit into the
2628 type of the LHS. If the LHS is a bitfield and the RHS is not
2629 a constant, then we can not record any equivalences for this
2630 statement since we would need to represent the widening or
2631 narrowing of RHS. This fixes gcc.c-torture/execute/921016-1.c
2632 and should not be necessary if GCC represented bitfields
2634 if (lhs_code == COMPONENT_REF
2635 && DECL_BIT_FIELD (TREE_OPERAND (lhs, 1)))
2637 if (TREE_CONSTANT (rhs))
2638 rhs = widen_bitfield (rhs, TREE_OPERAND (lhs, 1), lhs);
2642 /* If the value overflowed, then we can not use this equivalence. */
2643 if (rhs && ! is_gimple_min_invariant (rhs))
2649 /* Build a new statement with the RHS and LHS exchanged. */
2650 new = build2 (MODIFY_EXPR, TREE_TYPE (stmt), rhs, lhs);
2652 create_ssa_artficial_load_stmt (new, stmt);
2654 /* Finally enter the statement into the available expression
2656 lookup_avail_expr (new, true);
2661 /* Replace *OP_P in STMT with any known equivalent value for *OP_P from
2662 CONST_AND_COPIES. */
2665 cprop_operand (tree stmt, use_operand_p op_p)
2667 bool may_have_exposed_new_symbols = false;
2669 tree op = USE_FROM_PTR (op_p);
2671 /* If the operand has a known constant value or it is known to be a
2672 copy of some other variable, use the value or copy stored in
2673 CONST_AND_COPIES. */
2674 val = SSA_NAME_VALUE (op);
2675 if (val && val != op && TREE_CODE (val) != VALUE_HANDLE)
2677 tree op_type, val_type;
2679 /* Do not change the base variable in the virtual operand
2680 tables. That would make it impossible to reconstruct
2681 the renamed virtual operand if we later modify this
2682 statement. Also only allow the new value to be an SSA_NAME
2683 for propagation into virtual operands. */
2684 if (!is_gimple_reg (op)
2685 && (TREE_CODE (val) != SSA_NAME
2686 || is_gimple_reg (val)
2687 || get_virtual_var (val) != get_virtual_var (op)))
2690 /* Do not replace hard register operands in asm statements. */
2691 if (TREE_CODE (stmt) == ASM_EXPR
2692 && !may_propagate_copy_into_asm (op))
2695 /* Get the toplevel type of each operand. */
2696 op_type = TREE_TYPE (op);
2697 val_type = TREE_TYPE (val);
2699 /* While both types are pointers, get the type of the object
2701 while (POINTER_TYPE_P (op_type) && POINTER_TYPE_P (val_type))
2703 op_type = TREE_TYPE (op_type);
2704 val_type = TREE_TYPE (val_type);
2707 /* Make sure underlying types match before propagating a constant by
2708 converting the constant to the proper type. Note that convert may
2709 return a non-gimple expression, in which case we ignore this
2710 propagation opportunity. */
2711 if (TREE_CODE (val) != SSA_NAME)
2713 if (!lang_hooks.types_compatible_p (op_type, val_type))
2715 val = fold_convert (TREE_TYPE (op), val);
2716 if (!is_gimple_min_invariant (val))
2721 /* Certain operands are not allowed to be copy propagated due
2722 to their interaction with exception handling and some GCC
2724 else if (!may_propagate_copy (op, val))
2727 /* Do not propagate copies if the propagated value is at a deeper loop
2728 depth than the propagatee. Otherwise, this may move loop variant
2729 variables outside of their loops and prevent coalescing
2730 opportunities. If the value was loop invariant, it will be hoisted
2731 by LICM and exposed for copy propagation. */
2732 if (loop_depth_of_name (val) > loop_depth_of_name (op))
2736 if (dump_file && (dump_flags & TDF_DETAILS))
2738 fprintf (dump_file, " Replaced '");
2739 print_generic_expr (dump_file, op, dump_flags);
2740 fprintf (dump_file, "' with %s '",
2741 (TREE_CODE (val) != SSA_NAME ? "constant" : "variable"));
2742 print_generic_expr (dump_file, val, dump_flags);
2743 fprintf (dump_file, "'\n");
2746 /* If VAL is an ADDR_EXPR or a constant of pointer type, note
2747 that we may have exposed a new symbol for SSA renaming. */
2748 if (TREE_CODE (val) == ADDR_EXPR
2749 || (POINTER_TYPE_P (TREE_TYPE (op))
2750 && is_gimple_min_invariant (val)))
2751 may_have_exposed_new_symbols = true;
2753 if (TREE_CODE (val) != SSA_NAME)
2754 opt_stats.num_const_prop++;
2756 opt_stats.num_copy_prop++;
2758 propagate_value (op_p, val);
2760 /* And note that we modified this statement. This is now
2761 safe, even if we changed virtual operands since we will
2762 rescan the statement and rewrite its operands again. */
2763 mark_stmt_modified (stmt);
2765 return may_have_exposed_new_symbols;
2768 /* CONST_AND_COPIES is a table which maps an SSA_NAME to the current
2769 known value for that SSA_NAME (or NULL if no value is known).
2771 Propagate values from CONST_AND_COPIES into the uses, vuses and
2772 v_may_def_ops of STMT. */
2775 cprop_into_stmt (tree stmt)
2777 bool may_have_exposed_new_symbols = false;
2781 FOR_EACH_SSA_USE_OPERAND (op_p, stmt, iter, SSA_OP_ALL_USES)
2783 if (TREE_CODE (USE_FROM_PTR (op_p)) == SSA_NAME)
2784 may_have_exposed_new_symbols |= cprop_operand (stmt, op_p);
2787 return may_have_exposed_new_symbols;
2791 /* Optimize the statement pointed to by iterator SI.
2793 We try to perform some simplistic global redundancy elimination and
2794 constant propagation:
2796 1- To detect global redundancy, we keep track of expressions that have
2797 been computed in this block and its dominators. If we find that the
2798 same expression is computed more than once, we eliminate repeated
2799 computations by using the target of the first one.
2801 2- Constant values and copy assignments. This is used to do very
2802 simplistic constant and copy propagation. When a constant or copy
2803 assignment is found, we map the value on the RHS of the assignment to
2804 the variable in the LHS in the CONST_AND_COPIES table. */
2807 optimize_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
2808 basic_block bb, block_stmt_iterator si)
2811 tree stmt, old_stmt;
2812 bool may_optimize_p;
2813 bool may_have_exposed_new_symbols = false;
2815 old_stmt = stmt = bsi_stmt (si);
2817 if (TREE_CODE (stmt) == COND_EXPR)
2818 canonicalize_comparison (stmt);
2820 update_stmt_if_modified (stmt);
2821 ann = stmt_ann (stmt);
2822 opt_stats.num_stmts++;
2823 may_have_exposed_new_symbols = false;
2825 if (dump_file && (dump_flags & TDF_DETAILS))
2827 fprintf (dump_file, "Optimizing statement ");
2828 print_generic_stmt (dump_file, stmt, TDF_SLIM);
2831 /* Const/copy propagate into USES, VUSES and the RHS of V_MAY_DEFs. */
2832 may_have_exposed_new_symbols = cprop_into_stmt (stmt);
2834 /* If the statement has been modified with constant replacements,
2835 fold its RHS before checking for redundant computations. */
2840 /* Try to fold the statement making sure that STMT is kept
2842 if (fold_stmt (bsi_stmt_ptr (si)))
2844 stmt = bsi_stmt (si);
2845 ann = stmt_ann (stmt);
2847 if (dump_file && (dump_flags & TDF_DETAILS))
2849 fprintf (dump_file, " Folded to: ");
2850 print_generic_stmt (dump_file, stmt, TDF_SLIM);
2854 rhs = get_rhs (stmt);
2855 if (rhs && TREE_CODE (rhs) == ADDR_EXPR)
2856 recompute_tree_invariant_for_addr_expr (rhs);
2858 /* Constant/copy propagation above may change the set of
2859 virtual operands associated with this statement. Folding
2860 may remove the need for some virtual operands.
2862 Indicate we will need to rescan and rewrite the statement. */
2863 may_have_exposed_new_symbols = true;
2866 /* Check for redundant computations. Do this optimization only
2867 for assignments that have no volatile ops and conditionals. */
2868 may_optimize_p = (!ann->has_volatile_ops
2869 && ((TREE_CODE (stmt) == RETURN_EXPR
2870 && TREE_OPERAND (stmt, 0)
2871 && TREE_CODE (TREE_OPERAND (stmt, 0)) == MODIFY_EXPR
2872 && ! (TREE_SIDE_EFFECTS
2873 (TREE_OPERAND (TREE_OPERAND (stmt, 0), 1))))
2874 || (TREE_CODE (stmt) == MODIFY_EXPR
2875 && ! TREE_SIDE_EFFECTS (TREE_OPERAND (stmt, 1)))
2876 || TREE_CODE (stmt) == COND_EXPR
2877 || TREE_CODE (stmt) == SWITCH_EXPR));
2880 may_have_exposed_new_symbols
2881 |= eliminate_redundant_computations (stmt, ann);
2883 /* Record any additional equivalences created by this statement. */
2884 if (TREE_CODE (stmt) == MODIFY_EXPR)
2885 record_equivalences_from_stmt (stmt,
2889 /* If STMT is a COND_EXPR and it was modified, then we may know
2890 where it goes. If that is the case, then mark the CFG as altered.
2892 This will cause us to later call remove_unreachable_blocks and
2893 cleanup_tree_cfg when it is safe to do so. It is not safe to
2894 clean things up here since removal of edges and such can trigger
2895 the removal of PHI nodes, which in turn can release SSA_NAMEs to
2898 That's all fine and good, except that once SSA_NAMEs are released
2899 to the manager, we must not call create_ssa_name until all references
2900 to released SSA_NAMEs have been eliminated.
2902 All references to the deleted SSA_NAMEs can not be eliminated until
2903 we remove unreachable blocks.
2905 We can not remove unreachable blocks until after we have completed
2906 any queued jump threading.
2908 We can not complete any queued jump threads until we have taken
2909 appropriate variables out of SSA form. Taking variables out of
2910 SSA form can call create_ssa_name and thus we lose.
2912 Ultimately I suspect we're going to need to change the interface
2913 into the SSA_NAME manager. */
2919 if (TREE_CODE (stmt) == COND_EXPR)
2920 val = COND_EXPR_COND (stmt);
2921 else if (TREE_CODE (stmt) == SWITCH_EXPR)
2922 val = SWITCH_COND (stmt);
2924 if (val && TREE_CODE (val) == INTEGER_CST && find_taken_edge (bb, val))
2927 /* If we simplified a statement in such a way as to be shown that it
2928 cannot trap, update the eh information and the cfg to match. */
2929 if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
2931 bitmap_set_bit (need_eh_cleanup, bb->index);
2932 if (dump_file && (dump_flags & TDF_DETAILS))
2933 fprintf (dump_file, " Flagged to clear EH edges.\n");
2937 if (may_have_exposed_new_symbols)
2938 VEC_safe_push (tree, heap, stmts_to_rescan, bsi_stmt (si));
2941 /* Search for an existing instance of STMT in the AVAIL_EXPRS table. If
2942 found, return its LHS. Otherwise insert STMT in the table and return
2945 Also, when an expression is first inserted in the AVAIL_EXPRS table, it
2946 is also added to the stack pointed to by BLOCK_AVAIL_EXPRS_P, so that they
2947 can be removed when we finish processing this block and its children.
2949 NOTE: This function assumes that STMT is a MODIFY_EXPR node that
2950 contains no CALL_EXPR on its RHS and makes no volatile nor
2951 aliased references. */
2954 lookup_avail_expr (tree stmt, bool insert)
2959 struct expr_hash_elt *element = xmalloc (sizeof (struct expr_hash_elt));
2961 lhs = TREE_CODE (stmt) == MODIFY_EXPR ? TREE_OPERAND (stmt, 0) : NULL;
2963 initialize_hash_element (stmt, lhs, element);
2965 /* Don't bother remembering constant assignments and copy operations.
2966 Constants and copy operations are handled by the constant/copy propagator
2967 in optimize_stmt. */
2968 if (TREE_CODE (element->rhs) == SSA_NAME
2969 || is_gimple_min_invariant (element->rhs))
2975 /* If this is an equality test against zero, see if we have recorded a
2976 nonzero value for the variable in question. */
2977 if ((TREE_CODE (element->rhs) == EQ_EXPR
2978 || TREE_CODE (element->rhs) == NE_EXPR)
2979 && TREE_CODE (TREE_OPERAND (element->rhs, 0)) == SSA_NAME
2980 && integer_zerop (TREE_OPERAND (element->rhs, 1)))
2982 int indx = SSA_NAME_VERSION (TREE_OPERAND (element->rhs, 0));
2984 if (bitmap_bit_p (nonzero_vars, indx))
2986 tree t = element->rhs;
2988 return constant_boolean_node (TREE_CODE (t) != EQ_EXPR,
2993 /* Finally try to find the expression in the main expression hash table. */
2994 slot = htab_find_slot_with_hash (avail_exprs, element, element->hash,
2995 (insert ? INSERT : NO_INSERT));
3004 *slot = (void *) element;
3005 VEC_safe_push (tree, heap, avail_exprs_stack,
3006 stmt ? stmt : element->rhs);
3010 /* Extract the LHS of the assignment so that it can be used as the current
3011 definition of another variable. */
3012 lhs = ((struct expr_hash_elt *)*slot)->lhs;
3014 /* See if the LHS appears in the CONST_AND_COPIES table. If it does, then
3015 use the value from the const_and_copies table. */
3016 if (TREE_CODE (lhs) == SSA_NAME)
3018 temp = SSA_NAME_VALUE (lhs);
3019 if (temp && TREE_CODE (temp) != VALUE_HANDLE)
3027 /* Given a condition COND, record into HI_P, LO_P and INVERTED_P the
3028 range of values that result in the conditional having a true value.
3030 Return true if we are successful in extracting a range from COND and
3031 false if we are unsuccessful. */
3034 extract_range_from_cond (tree cond, tree *hi_p, tree *lo_p, int *inverted_p)
3036 tree op1 = TREE_OPERAND (cond, 1);
3037 tree high, low, type;
3040 type = TREE_TYPE (op1);
3042 /* Experiments have shown that it's rarely, if ever useful to
3043 record ranges for enumerations. Presumably this is due to
3044 the fact that they're rarely used directly. They are typically
3045 cast into an integer type and used that way. */
3046 if (TREE_CODE (type) != INTEGER_TYPE)
3049 switch (TREE_CODE (cond))
3064 /* Get the highest value of the type. If not a constant, use that
3065 of its base type, if it has one. */
3066 high = TYPE_MAX_VALUE (type);
3067 if (TREE_CODE (high) != INTEGER_CST && TREE_TYPE (type))
3068 high = TYPE_MAX_VALUE (TREE_TYPE (type));
3073 high = TYPE_MAX_VALUE (type);
3074 if (TREE_CODE (high) != INTEGER_CST && TREE_TYPE (type))
3075 high = TYPE_MAX_VALUE (TREE_TYPE (type));
3076 if (!tree_int_cst_lt (op1, high))
3078 low = int_const_binop (PLUS_EXPR, op1, integer_one_node, 1);
3084 low = TYPE_MIN_VALUE (type);
3085 if (TREE_CODE (low) != INTEGER_CST && TREE_TYPE (type))
3086 low = TYPE_MIN_VALUE (TREE_TYPE (type));
3091 low = TYPE_MIN_VALUE (type);
3092 if (TREE_CODE (low) != INTEGER_CST && TREE_TYPE (type))
3093 low = TYPE_MIN_VALUE (TREE_TYPE (type));
3094 if (!tree_int_cst_lt (low, op1))
3096 high = int_const_binop (MINUS_EXPR, op1, integer_one_node, 1);
3106 *inverted_p = inverted;
3110 /* Record a range created by COND for basic block BB. */
3113 record_range (tree cond, basic_block bb)
3115 enum tree_code code = TREE_CODE (cond);
3117 /* We explicitly ignore NE_EXPRs and all the unordered comparisons.
3118 They rarely allow for meaningful range optimizations and significantly
3119 complicate the implementation. */
3120 if ((code == LT_EXPR || code == LE_EXPR || code == GT_EXPR
3121 || code == GE_EXPR || code == EQ_EXPR)
3122 && TREE_CODE (TREE_TYPE (TREE_OPERAND (cond, 1))) == INTEGER_TYPE)
3124 struct vrp_hash_elt *vrp_hash_elt;
3125 struct vrp_element *element;
3126 VEC(vrp_element_p,heap) **vrp_records_p;
3130 vrp_hash_elt = xmalloc (sizeof (struct vrp_hash_elt));
3131 vrp_hash_elt->var = TREE_OPERAND (cond, 0);
3132 vrp_hash_elt->records = NULL;
3133 slot = htab_find_slot (vrp_data, vrp_hash_elt, INSERT);
3136 *slot = (void *) vrp_hash_elt;
3138 vrp_free (vrp_hash_elt);
3140 vrp_hash_elt = (struct vrp_hash_elt *) *slot;
3141 vrp_records_p = &vrp_hash_elt->records;
3143 element = ggc_alloc (sizeof (struct vrp_element));
3144 element->low = NULL;
3145 element->high = NULL;
3146 element->cond = cond;
3149 VEC_safe_push (vrp_element_p, heap, *vrp_records_p, element);
3150 VEC_safe_push (tree, heap, vrp_variables_stack, TREE_OPERAND (cond, 0));
3154 /* Hashing and equality functions for VRP_DATA.
3156 Since this hash table is addressed by SSA_NAMEs, we can hash on
3157 their version number and equality can be determined with a
3158 pointer comparison. */
3161 vrp_hash (const void *p)
3163 tree var = ((struct vrp_hash_elt *)p)->var;
3165 return SSA_NAME_VERSION (var);
3169 vrp_eq (const void *p1, const void *p2)
3171 tree var1 = ((struct vrp_hash_elt *)p1)->var;
3172 tree var2 = ((struct vrp_hash_elt *)p2)->var;
3174 return var1 == var2;
3177 /* Hashing and equality functions for AVAIL_EXPRS. The table stores
3178 MODIFY_EXPR statements. We compute a value number for expressions using
3179 the code of the expression and the SSA numbers of its operands. */
3182 avail_expr_hash (const void *p)
3184 tree stmt = ((struct expr_hash_elt *)p)->stmt;
3185 tree rhs = ((struct expr_hash_elt *)p)->rhs;
3190 /* iterative_hash_expr knows how to deal with any expression and
3191 deals with commutative operators as well, so just use it instead
3192 of duplicating such complexities here. */
3193 val = iterative_hash_expr (rhs, val);
3195 /* If the hash table entry is not associated with a statement, then we
3196 can just hash the expression and not worry about virtual operands
3198 if (!stmt || !stmt_ann (stmt))
3201 /* Add the SSA version numbers of every vuse operand. This is important
3202 because compound variables like arrays are not renamed in the
3203 operands. Rather, the rename is done on the virtual variable
3204 representing all the elements of the array. */
3205 FOR_EACH_SSA_TREE_OPERAND (vuse, stmt, iter, SSA_OP_VUSE)
3206 val = iterative_hash_expr (vuse, val);
3212 real_avail_expr_hash (const void *p)
3214 return ((const struct expr_hash_elt *)p)->hash;
3218 avail_expr_eq (const void *p1, const void *p2)
3220 tree stmt1 = ((struct expr_hash_elt *)p1)->stmt;
3221 tree rhs1 = ((struct expr_hash_elt *)p1)->rhs;
3222 tree stmt2 = ((struct expr_hash_elt *)p2)->stmt;
3223 tree rhs2 = ((struct expr_hash_elt *)p2)->rhs;
3225 /* If they are the same physical expression, return true. */
3226 if (rhs1 == rhs2 && stmt1 == stmt2)
3229 /* If their codes are not equal, then quit now. */
3230 if (TREE_CODE (rhs1) != TREE_CODE (rhs2))
3233 /* In case of a collision, both RHS have to be identical and have the
3234 same VUSE operands. */
3235 if ((TREE_TYPE (rhs1) == TREE_TYPE (rhs2)
3236 || lang_hooks.types_compatible_p (TREE_TYPE (rhs1), TREE_TYPE (rhs2)))
3237 && operand_equal_p (rhs1, rhs2, OEP_PURE_SAME))
3239 bool ret = compare_ssa_operands_equal (stmt1, stmt2, SSA_OP_VUSE);
3240 gcc_assert (!ret || ((struct expr_hash_elt *)p1)->hash
3241 == ((struct expr_hash_elt *)p2)->hash);