2 Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
3 Contributed by Daniel Berlin <dan@dberlin.org> and Steven Bosscher
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GCC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
25 #include "coretypes.h"
30 #include "basic-block.h"
31 #include "diagnostic.h"
32 #include "tree-inline.h"
33 #include "tree-flow.h"
34 #include "tree-gimple.h"
35 #include "tree-dump.h"
39 #include "tree-iterator.h"
41 #include "alloc-pool.h"
42 #include "tree-pass.h"
44 #include "splay-tree.h"
46 #include "langhooks.h"
50 1. Avail sets can be shared by making an avail_find_leader that
51 walks up the dominator tree and looks in those avail sets.
52 This might affect code optimality, it's unclear right now.
53 2. Load motion can be performed by value numbering the loads the
54 same as we do other expressions. This requires iterative
55 hashing the vuses into the values. Right now we simply assign
56 a new value every time we see a statement with a vuse.
57 3. Strength reduction can be performed by anticipating expressions
58 we can repair later on.
59 4. Our canonicalization of expressions during lookups don't take
60 constants into account very well. In particular, we don't fold
61 anywhere, so we can get situations where we stupidly think
62 something is a new value (a + 1 + 1 vs a + 2). This is somewhat
63 expensive to fix, but it does expose a lot more eliminations.
64 It may or not be worth it, depending on how critical you
65 consider PRE vs just plain GRE.
68 /* For ease of terminology, "expression node" in the below refers to
69 every expression node but MODIFY_EXPR, because MODIFY_EXPR's represent
70 the actual statement containing the expressions we care about, and
71 we cache the value number by putting it in the expression. */
75 First we walk the statements to generate the AVAIL sets, the
76 EXP_GEN sets, and the tmp_gen sets. EXP_GEN sets represent the
77 generation of values/expressions by a given block. We use them
78 when computing the ANTIC sets. The AVAIL sets consist of
79 SSA_NAME's that represent values, so we know what values are
80 available in what blocks. AVAIL is a forward dataflow problem. In
81 SSA, values are never killed, so we don't need a kill set, or a
82 fixpoint iteration, in order to calculate the AVAIL sets. In
83 traditional parlance, AVAIL sets tell us the downsafety of the
86 Next, we generate the ANTIC sets. These sets represent the
87 anticipatable expressions. ANTIC is a backwards dataflow
88 problem.An expression is anticipatable in a given block if it could
89 be generated in that block. This means that if we had to perform
90 an insertion in that block, of the value of that expression, we
91 could. Calculating the ANTIC sets requires phi translation of
92 expressions, because the flow goes backwards through phis. We must
93 iterate to a fixpoint of the ANTIC sets, because we have a kill
94 set. Even in SSA form, values are not live over the entire
95 function, only from their definition point onwards. So we have to
96 remove values from the ANTIC set once we go past the definition
97 point of the leaders that make them up.
98 compute_antic/compute_antic_aux performs this computation.
100 Third, we perform insertions to make partially redundant
101 expressions fully redundant.
103 An expression is partially redundant (excluding partial
106 1. It is AVAIL in some, but not all, of the predecessors of a
108 2. It is ANTIC in all the predecessors.
110 In order to make it fully redundant, we insert the expression into
111 the predecessors where it is not available, but is ANTIC.
112 insert/insert_aux performs this insertion.
114 Fourth, we eliminate fully redundant expressions.
115 This is a simple statement walk that replaces redundant
116 calculations with the now available values. */
118 /* Representations of value numbers:
120 Value numbers are represented using the "value handle" approach.
121 This means that each SSA_NAME (and for other reasons to be
122 disclosed in a moment, expression nodes) has a value handle that
123 can be retrieved through get_value_handle. This value handle, *is*
124 the value number of the SSA_NAME. You can pointer compare the
125 value handles for equivalence purposes.
127 For debugging reasons, the value handle is internally more than
128 just a number, it is a VAR_DECL named "value.x", where x is a
129 unique number for each value number in use. This allows
130 expressions with SSA_NAMES replaced by value handles to still be
131 pretty printed in a sane way. They simply print as "value.3 *
134 Expression nodes have value handles associated with them as a
135 cache. Otherwise, we'd have to look them up again in the hash
136 table This makes significant difference (factor of two or more) on
137 some test cases. They can be thrown away after the pass is
140 /* Representation of expressions on value numbers:
142 In some portions of this code, you will notice we allocate "fake"
143 analogues to the expression we are value numbering, and replace the
144 operands with the values of the expression. Since we work on
145 values, and not just names, we canonicalize expressions to value
146 expressions for use in the ANTIC sets, the EXP_GEN set, etc.
148 This is theoretically unnecessary, it just saves a bunch of
149 repeated get_value_handle and find_leader calls in the remainder of
150 the code, trading off temporary memory usage for speed. The tree
151 nodes aren't actually creating more garbage, since they are
152 allocated in a special pools which are thrown away at the end of
155 All of this also means that if you print the EXP_GEN or ANTIC sets,
156 you will see "value.5 + value.7" in the set, instead of "a_55 +
157 b_66" or something. The only thing that actually cares about
158 seeing the value leaders is phi translation, and it needs to be
159 able to find the leader for a value in an arbitrary block, so this
160 "value expression" form is perfect for it (otherwise you'd do
161 get_value_handle->find_leader->translate->get_value_handle->find_leader).*/
164 /* Representation of sets:
166 There are currently two types of sets used, hopefully to be unified soon.
167 The AVAIL sets do not need to be sorted in any particular order,
168 and thus, are simply represented as two bitmaps, one that keeps
169 track of values present in the set, and one that keeps track of
170 expressions present in the set.
172 The other sets are represented as doubly linked lists kept in topological
173 order, with an optional supporting bitmap of values present in the
174 set. The sets represent values, and the elements can be values or
175 expressions. The elements can appear in different sets, but each
176 element can only appear once in each set.
178 Since each node in the set represents a value, we also want to be
179 able to map expression, set pairs to something that tells us
180 whether the value is present is a set. We use a per-set bitmap for
181 that. The value handles also point to a linked list of the
182 expressions they represent via a tree annotation. This is mainly
183 useful only for debugging, since we don't do identity lookups. */
186 /* A value set element. Basically a single linked list of
187 expressions/values. */
188 typedef struct value_set_node
193 /* A pointer to the next element of the value set. */
194 struct value_set_node *next;
198 /* A value set. This is a singly linked list of value_set_node
199 elements with a possible bitmap that tells us what values exist in
200 the set. This set must be kept in topologically sorted order. */
201 typedef struct value_set
203 /* The head of the list. Used for iterating over the list in
205 value_set_node_t head;
207 /* The tail of the list. Used for tail insertions, which are
208 necessary to keep the set in topologically sorted order because
209 of how the set is built. */
210 value_set_node_t tail;
212 /* The length of the list. */
215 /* True if the set is indexed, which means it contains a backing
216 bitmap for quick determination of whether certain values exist in the
220 /* The bitmap of values that exist in the set. May be NULL in an
221 empty or non-indexed set. */
227 /* An unordered bitmap set. One bitmap tracks values, the other,
229 typedef struct bitmap_set
235 /* Sets that we need to keep track of. */
236 typedef struct bb_value_sets
238 /* The EXP_GEN set, which represents expressions/values generated in
242 /* The PHI_GEN set, which represents PHI results generated in a
244 bitmap_set_t phi_gen;
246 /* The TMP_GEN set, which represents results/temporaries generated
247 in a basic block. IE the LHS of an expression. */
248 bitmap_set_t tmp_gen;
250 /* The AVAIL_OUT set, which represents which values are available in
251 a given basic block. */
252 bitmap_set_t avail_out;
254 /* The ANTIC_IN set, which represents which values are anticiptable
255 in a given basic block. */
256 value_set_t antic_in;
258 /* The NEW_SETS set, which is used during insertion to augment the
259 AVAIL_OUT set of blocks with the new insertions performed during
260 the current iteration. */
261 bitmap_set_t new_sets;
264 #define EXP_GEN(BB) ((bb_value_sets_t) ((BB)->aux))->exp_gen
265 #define PHI_GEN(BB) ((bb_value_sets_t) ((BB)->aux))->phi_gen
266 #define TMP_GEN(BB) ((bb_value_sets_t) ((BB)->aux))->tmp_gen
267 #define AVAIL_OUT(BB) ((bb_value_sets_t) ((BB)->aux))->avail_out
268 #define ANTIC_IN(BB) ((bb_value_sets_t) ((BB)->aux))->antic_in
269 #define NEW_SETS(BB) ((bb_value_sets_t) ((BB)->aux))->new_sets
271 /* This structure is used to keep track of statistics on what
272 optimization PRE was able to perform. */
275 /* The number of RHS computations eliminated by PRE. */
278 /* The number of new expressions/temporaries generated by PRE. */
281 /* The number of new PHI nodes added by PRE. */
286 static tree bitmap_find_leader (bitmap_set_t, tree);
287 static tree find_leader (value_set_t, tree);
288 static void value_insert_into_set (value_set_t, tree);
289 static void bitmap_value_insert_into_set (bitmap_set_t, tree);
290 static void bitmap_value_replace_in_set (bitmap_set_t, tree);
291 static void insert_into_set (value_set_t, tree);
292 static void bitmap_set_copy (bitmap_set_t, bitmap_set_t);
293 static bool bitmap_set_contains_value (bitmap_set_t, tree);
294 static bitmap_set_t bitmap_set_new (void);
295 static value_set_t set_new (bool);
296 static bool is_undefined_value (tree);
297 static tree create_expression_by_pieces (basic_block, tree, tree);
300 /* We can add and remove elements and entries to and from sets
301 and hash tables, so we use alloc pools for them. */
303 static alloc_pool value_set_pool;
304 static alloc_pool bitmap_set_pool;
305 static alloc_pool value_set_node_pool;
306 static alloc_pool binary_node_pool;
307 static alloc_pool unary_node_pool;
308 static alloc_pool reference_node_pool;
309 static bitmap_obstack grand_bitmap_obstack;
311 /* Set of blocks with statements that have had its EH information
313 static bitmap need_eh_cleanup;
315 /* The phi_translate_table caches phi translations for a given
316 expression and predecessor. */
318 static htab_t phi_translate_table;
320 /* A three tuple {e, pred, v} used to cache phi translations in the
321 phi_translate_table. */
323 typedef struct expr_pred_trans_d
325 /* The expression. */
328 /* The predecessor block along which we translated the expression. */
331 /* The value that resulted from the translation. */
334 /* The hashcode for the expression, pred pair. This is cached for
337 } *expr_pred_trans_t;
339 /* Return the hash value for a phi translation table entry. */
342 expr_pred_trans_hash (const void *p)
344 const expr_pred_trans_t ve = (expr_pred_trans_t) p;
348 /* Return true if two phi translation table entries are the same.
349 P1 and P2 should point to the expr_pred_trans_t's to be compared.*/
352 expr_pred_trans_eq (const void *p1, const void *p2)
354 const expr_pred_trans_t ve1 = (expr_pred_trans_t) p1;
355 const expr_pred_trans_t ve2 = (expr_pred_trans_t) p2;
356 basic_block b1 = ve1->pred;
357 basic_block b2 = ve2->pred;
360 /* If they are not translations for the same basic block, they can't
365 /* If they are for the same basic block, determine if the
366 expressions are equal. */
367 if (expressions_equal_p (ve1->e, ve2->e))
373 /* Search in the phi translation table for the translation of
374 expression E in basic block PRED. Return the translated value, if
375 found, NULL otherwise. */
378 phi_trans_lookup (tree e, basic_block pred)
381 struct expr_pred_trans_d ept;
384 ept.hashcode = vn_compute (e, (unsigned long) pred, NULL);
385 slot = htab_find_slot_with_hash (phi_translate_table, &ept, ept.hashcode,
390 return ((expr_pred_trans_t) *slot)->v;
394 /* Add the tuple mapping from {expression E, basic block PRED} to
395 value V, to the phi translation table. */
398 phi_trans_add (tree e, tree v, basic_block pred)
401 expr_pred_trans_t new_pair = xmalloc (sizeof (*new_pair));
403 new_pair->pred = pred;
405 new_pair->hashcode = vn_compute (e, (unsigned long) pred, NULL);
406 slot = htab_find_slot_with_hash (phi_translate_table, new_pair,
407 new_pair->hashcode, INSERT);
410 *slot = (void *) new_pair;
414 /* Add expression E to the expression set of value V. */
417 add_to_value (tree v, tree e)
419 /* Constants have no expression sets. */
420 if (is_gimple_min_invariant (v))
423 if (VALUE_HANDLE_EXPR_SET (v) == NULL)
424 VALUE_HANDLE_EXPR_SET (v) = set_new (false);
426 insert_into_set (VALUE_HANDLE_EXPR_SET (v), e);
430 /* Return true if value V exists in the bitmap for SET. */
433 value_exists_in_set_bitmap (value_set_t set, tree v)
438 return bitmap_bit_p (set->values, VALUE_HANDLE_ID (v));
442 /* Remove value V from the bitmap for SET. */
445 value_remove_from_set_bitmap (value_set_t set, tree v)
447 gcc_assert (set->indexed);
452 bitmap_clear_bit (set->values, VALUE_HANDLE_ID (v));
456 /* Insert the value number V into the bitmap of values existing in
460 value_insert_into_set_bitmap (value_set_t set, tree v)
462 gcc_assert (set->indexed);
464 if (set->values == NULL)
465 set->values = BITMAP_ALLOC (&grand_bitmap_obstack);
467 bitmap_set_bit (set->values, VALUE_HANDLE_ID (v));
471 /* Create a new bitmap set and return it. */
474 bitmap_set_new (void)
476 bitmap_set_t ret = pool_alloc (bitmap_set_pool);
477 ret->expressions = BITMAP_ALLOC (&grand_bitmap_obstack);
478 ret->values = BITMAP_ALLOC (&grand_bitmap_obstack);
482 /* Create a new set. */
485 set_new (bool indexed)
488 ret = pool_alloc (value_set_pool);
489 ret->head = ret->tail = NULL;
491 ret->indexed = indexed;
496 /* Insert an expression EXPR into a bitmapped set. */
499 bitmap_insert_into_set (bitmap_set_t set, tree expr)
502 /* XXX: For now, we only let SSA_NAMES into the bitmap sets. */
503 gcc_assert (TREE_CODE (expr) == SSA_NAME);
504 val = get_value_handle (expr);
507 if (!is_gimple_min_invariant (val))
509 bitmap_set_bit (set->values, VALUE_HANDLE_ID (val));
510 bitmap_set_bit (set->expressions, SSA_NAME_VERSION (expr));
514 /* Insert EXPR into SET. */
517 insert_into_set (value_set_t set, tree expr)
519 value_set_node_t newnode = pool_alloc (value_set_node_pool);
520 tree val = get_value_handle (expr);
523 if (is_gimple_min_invariant (val))
526 /* For indexed sets, insert the value into the set value bitmap.
527 For all sets, add it to the linked list and increment the list
530 value_insert_into_set_bitmap (set, val);
532 newnode->next = NULL;
533 newnode->expr = expr;
535 if (set->head == NULL)
537 set->head = set->tail = newnode;
541 set->tail->next = newnode;
546 /* Copy a bitmapped set ORIG, into bitmapped set DEST. */
549 bitmap_set_copy (bitmap_set_t dest, bitmap_set_t orig)
551 bitmap_copy (dest->expressions, orig->expressions);
552 bitmap_copy (dest->values, orig->values);
555 /* Copy the set ORIG to the set DEST. */
558 set_copy (value_set_t dest, value_set_t orig)
560 value_set_node_t node;
562 if (!orig || !orig->head)
565 for (node = orig->head;
569 insert_into_set (dest, node->expr);
573 /* Remove EXPR from SET. */
576 set_remove (value_set_t set, tree expr)
578 value_set_node_t node, prev;
580 /* Remove the value of EXPR from the bitmap, decrement the set
581 length, and remove it from the actual double linked list. */
582 value_remove_from_set_bitmap (set, get_value_handle (expr));
585 for (node = set->head;
587 prev = node, node = node->next)
589 if (node->expr == expr)
592 set->head = node->next;
594 prev->next= node->next;
596 if (node == set->tail)
598 pool_free (value_set_node_pool, node);
604 /* Return true if SET contains the value VAL. */
607 set_contains_value (value_set_t set, tree val)
609 /* All constants are in every set. */
610 if (is_gimple_min_invariant (val))
613 if (set->length == 0)
616 return value_exists_in_set_bitmap (set, val);
619 /* Return true if bitmapped set SET contains the expression EXPR. */
621 bitmap_set_contains (bitmap_set_t set, tree expr)
623 /* All constants are in every set. */
624 if (is_gimple_min_invariant (get_value_handle (expr)))
627 /* XXX: Bitmapped sets only contain SSA_NAME's for now. */
628 if (TREE_CODE (expr) != SSA_NAME)
630 return bitmap_bit_p (set->expressions, SSA_NAME_VERSION (expr));
634 /* Return true if bitmapped set SET contains the value VAL. */
637 bitmap_set_contains_value (bitmap_set_t set, tree val)
639 if (is_gimple_min_invariant (val))
641 return bitmap_bit_p (set->values, VALUE_HANDLE_ID (val));
644 /* Replace an instance of value LOOKFOR with expression EXPR in SET. */
647 bitmap_set_replace_value (bitmap_set_t set, tree lookfor, tree expr)
650 value_set_node_t node;
651 if (is_gimple_min_invariant (lookfor))
653 if (!bitmap_set_contains_value (set, lookfor))
655 /* The number of expressions having a given value is usually
656 significantly less than the total number of expressions in SET.
657 Thus, rather than check, for each expression in SET, whether it
658 has the value LOOKFOR, we walk the reverse mapping that tells us
659 what expressions have a given value, and see if any of those
660 expressions are in our set. For large testcases, this is about
661 5-10x faster than walking the bitmap. If this is somehow a
662 significant lose for some cases, we can choose which set to walk
663 based on the set size. */
664 exprset = VALUE_HANDLE_EXPR_SET (lookfor);
665 for (node = exprset->head; node; node = node->next)
667 if (TREE_CODE (node->expr) == SSA_NAME)
669 if (bitmap_bit_p (set->expressions, SSA_NAME_VERSION (node->expr)))
671 bitmap_clear_bit (set->expressions, SSA_NAME_VERSION (node->expr));
672 bitmap_set_bit (set->expressions, SSA_NAME_VERSION (expr));
679 /* Subtract bitmapped set B from value set A, and return the new set. */
682 bitmap_set_subtract_from_value_set (value_set_t a, bitmap_set_t b,
685 value_set_t ret = set_new (indexed);
686 value_set_node_t node;
691 if (!bitmap_set_contains (b, node->expr))
692 insert_into_set (ret, node->expr);
697 /* Return true if two sets are equal. */
700 set_equal (value_set_t a, value_set_t b)
702 value_set_node_t node;
704 if (a->length != b->length)
710 if (!set_contains_value (b, get_value_handle (node->expr)))
716 /* Replace an instance of EXPR's VALUE with EXPR in SET. */
719 bitmap_value_replace_in_set (bitmap_set_t set, tree expr)
721 tree val = get_value_handle (expr);
722 bitmap_set_replace_value (set, val, expr);
725 /* Insert EXPR into SET if EXPR's value is not already present in
729 bitmap_value_insert_into_set (bitmap_set_t set, tree expr)
731 tree val = get_value_handle (expr);
733 if (is_gimple_min_invariant (val))
736 if (!bitmap_set_contains_value (set, val))
737 bitmap_insert_into_set (set, expr);
740 /* Insert the value for EXPR into SET, if it doesn't exist already. */
743 value_insert_into_set (value_set_t set, tree expr)
745 tree val = get_value_handle (expr);
747 /* Constant and invariant values exist everywhere, and thus,
748 actually keeping them in the sets is pointless. */
749 if (is_gimple_min_invariant (val))
752 if (!set_contains_value (set, val))
753 insert_into_set (set, expr);
757 /* Print out SET to OUTFILE. */
760 bitmap_print_value_set (FILE *outfile, bitmap_set_t set,
761 const char *setname, int blockindex)
763 fprintf (outfile, "%s[%d] := { ", setname, blockindex);
770 EXECUTE_IF_SET_IN_BITMAP (set->expressions, 0, i, bi)
773 fprintf (outfile, ", ");
775 print_generic_expr (outfile, ssa_name (i), 0);
777 fprintf (outfile, " (");
778 print_generic_expr (outfile, get_value_handle (ssa_name (i)), 0);
779 fprintf (outfile, ") ");
782 fprintf (outfile, " }\n");
784 /* Print out the value_set SET to OUTFILE. */
787 print_value_set (FILE *outfile, value_set_t set,
788 const char *setname, int blockindex)
790 value_set_node_t node;
791 fprintf (outfile, "%s[%d] := { ", setname, blockindex);
794 for (node = set->head;
798 print_generic_expr (outfile, node->expr, 0);
800 fprintf (outfile, " (");
801 print_generic_expr (outfile, get_value_handle (node->expr), 0);
802 fprintf (outfile, ") ");
805 fprintf (outfile, ", ");
809 fprintf (outfile, " }\n");
812 /* Print out the expressions that have VAL to OUTFILE. */
815 print_value_expressions (FILE *outfile, tree val)
817 if (VALUE_HANDLE_EXPR_SET (val))
820 sprintf (s, "VH.%04d", VALUE_HANDLE_ID (val));
821 print_value_set (outfile, VALUE_HANDLE_EXPR_SET (val), s, 0);
827 debug_value_expressions (tree val)
829 print_value_expressions (stderr, val);
833 void debug_value_set (value_set_t, const char *, int);
836 debug_value_set (value_set_t set, const char *setname, int blockindex)
838 print_value_set (stderr, set, setname, blockindex);
841 /* Translate EXPR using phis in PHIBLOCK, so that it has the values of
842 the phis in PRED. Return NULL if we can't find a leader for each
843 part of the translated expression. */
846 phi_translate (tree expr, value_set_t set, basic_block pred,
847 basic_block phiblock)
849 tree phitrans = NULL;
855 if (is_gimple_min_invariant (expr))
858 /* Phi translations of a given expression don't change. */
859 phitrans = phi_trans_lookup (expr, pred);
863 switch (TREE_CODE_CLASS (TREE_CODE (expr)))
866 /* XXX: Until we have PRE of loads working, none will be ANTIC. */
871 tree oldop1 = TREE_OPERAND (expr, 0);
872 tree oldop2 = TREE_OPERAND (expr, 1);
877 newop1 = phi_translate (find_leader (set, oldop1),
878 set, pred, phiblock);
881 newop2 = phi_translate (find_leader (set, oldop2),
882 set, pred, phiblock);
885 if (newop1 != oldop1 || newop2 != oldop2)
887 newexpr = pool_alloc (binary_node_pool);
888 memcpy (newexpr, expr, tree_size (expr));
889 create_tree_ann (newexpr);
890 TREE_OPERAND (newexpr, 0) = newop1 == oldop1 ? oldop1 : get_value_handle (newop1);
891 TREE_OPERAND (newexpr, 1) = newop2 == oldop2 ? oldop2 : get_value_handle (newop2);
892 vn_lookup_or_add (newexpr, NULL);
894 phi_trans_add (oldexpr, newexpr, pred);
901 tree oldop1 = TREE_OPERAND (expr, 0);
905 newop1 = phi_translate (find_leader (set, oldop1),
906 set, pred, phiblock);
909 if (newop1 != oldop1)
911 newexpr = pool_alloc (unary_node_pool);
912 memcpy (newexpr, expr, tree_size (expr));
913 create_tree_ann (newexpr);
914 TREE_OPERAND (newexpr, 0) = get_value_handle (newop1);
915 vn_lookup_or_add (newexpr, NULL);
917 phi_trans_add (oldexpr, newexpr, pred);
922 case tcc_exceptional:
926 gcc_assert (TREE_CODE (expr) == SSA_NAME);
927 if (TREE_CODE (SSA_NAME_DEF_STMT (expr)) == PHI_NODE)
928 phi = SSA_NAME_DEF_STMT (expr);
932 e = find_edge (pred, bb_for_stmt (phi));
935 if (is_undefined_value (PHI_ARG_DEF (phi, e->dest_idx)))
937 vn_lookup_or_add (PHI_ARG_DEF (phi, e->dest_idx), NULL);
938 return PHI_ARG_DEF (phi, e->dest_idx);
949 phi_translate_set (value_set_t dest, value_set_t set, basic_block pred,
950 basic_block phiblock)
952 value_set_node_t node;
953 for (node = set->head;
958 translated = phi_translate (node->expr, set, pred, phiblock);
959 phi_trans_add (node->expr, translated, pred);
961 if (translated != NULL)
962 value_insert_into_set (dest, translated);
966 /* Find the leader for a value (i.e., the name representing that
967 value) in a given set, and return it. Return NULL if no leader is
971 bitmap_find_leader (bitmap_set_t set, tree val)
976 if (is_gimple_min_invariant (val))
978 if (bitmap_set_contains_value (set, val))
980 /* Rather than walk the entire bitmap of expressions, and see
981 whether any of them has the value we are looking for, we look
982 at the reverse mapping, which tells us the set of expressions
983 that have a given value (IE value->expressions with that
984 value) and see if any of those expressions are in our set.
985 The number of expressions per value is usually significantly
986 less than the number of expressions in the set. In fact, for
987 large testcases, doing it this way is roughly 5-10x faster
988 than walking the bitmap.
989 If this is somehow a significant lose for some cases, we can
990 choose which set to walk based on which set is smaller. */
992 value_set_node_t node;
993 exprset = VALUE_HANDLE_EXPR_SET (val);
994 for (node = exprset->head; node; node = node->next)
996 if (TREE_CODE (node->expr) == SSA_NAME)
998 if (bitmap_bit_p (set->expressions,
999 SSA_NAME_VERSION (node->expr)))
1008 /* Find the leader for a value (i.e., the name representing that
1009 value) in a given set, and return it. Return NULL if no leader is
1013 find_leader (value_set_t set, tree val)
1015 value_set_node_t node;
1020 /* Constants represent themselves. */
1021 if (is_gimple_min_invariant (val))
1024 if (set->length == 0)
1027 if (value_exists_in_set_bitmap (set, val))
1029 for (node = set->head;
1033 if (get_value_handle (node->expr) == val)
1041 /* Determine if the expression EXPR is valid in SET. This means that
1042 we have a leader for each part of the expression (if it consists of
1043 values), or the expression is an SSA_NAME.
1045 NB: We never should run into a case where we have SSA_NAME +
1046 SSA_NAME or SSA_NAME + value. The sets valid_in_set is called on,
1047 the ANTIC sets, will only ever have SSA_NAME's or binary value
1048 expression (IE VALUE1 + VALUE2) */
1051 valid_in_set (value_set_t set, tree expr)
1053 switch (TREE_CODE_CLASS (TREE_CODE (expr)))
1057 tree op1 = TREE_OPERAND (expr, 0);
1058 tree op2 = TREE_OPERAND (expr, 1);
1059 return set_contains_value (set, op1) && set_contains_value (set, op2);
1064 tree op1 = TREE_OPERAND (expr, 0);
1065 return set_contains_value (set, op1);
1069 /* XXX: Until PRE of loads works, no reference nodes are ANTIC. */
1072 case tcc_exceptional:
1073 gcc_assert (TREE_CODE (expr) == SSA_NAME);
1077 /* No other cases should be encountered. */
1082 /* Clean the set of expressions that are no longer valid in SET. This
1083 means expressions that are made up of values we have no leaders for
1087 clean (value_set_t set)
1089 value_set_node_t node;
1090 value_set_node_t next;
1095 if (!valid_in_set (set, node->expr))
1096 set_remove (set, node->expr);
1101 DEF_VEC_MALLOC_P (basic_block);
1103 /* Compute the ANTIC set for BLOCK.
1105 ANTIC_OUT[BLOCK] = intersection of ANTIC_IN[b] for all succ(BLOCK), if
1107 ANTIC_OUT[BLOCK] = phi_translate (ANTIC_IN[succ(BLOCK)]) if
1110 ANTIC_IN[BLOCK] = clean(ANTIC_OUT[BLOCK] U EXP_GEN[BLOCK] -
1113 Iterate until fixpointed.
1115 XXX: It would be nice to either write a set_clear, and use it for
1116 antic_out, or to mark the antic_out set as deleted at the end
1117 of this routine, so that the pool can hand the same memory back out
1118 again for the next antic_out. */
1122 compute_antic_aux (basic_block block)
1126 bool changed = false;
1127 value_set_t S, old, ANTIC_OUT;
1128 value_set_node_t node;
1130 ANTIC_OUT = S = NULL;
1131 /* If any edges from predecessors are abnormal, antic_in is empty, so
1132 punt. Remember that the block has an incoming abnormal edge by
1133 setting the BB_VISITED flag. */
1134 if (! (block->flags & BB_VISITED))
1137 FOR_EACH_EDGE (e, ei, block->preds)
1138 if (e->flags & EDGE_ABNORMAL)
1140 block->flags |= BB_VISITED;
1144 if (block->flags & BB_VISITED)
1151 old = set_new (false);
1152 set_copy (old, ANTIC_IN (block));
1153 ANTIC_OUT = set_new (true);
1155 /* If the block has no successors, ANTIC_OUT is empty, because it is
1157 if (EDGE_COUNT (block->succs) == 0);
1159 /* If we have one successor, we could have some phi nodes to
1160 translate through. */
1161 else if (EDGE_COUNT (block->succs) == 1)
1163 phi_translate_set (ANTIC_OUT, ANTIC_IN(EDGE_SUCC (block, 0)->dest),
1164 block, EDGE_SUCC (block, 0)->dest);
1166 /* If we have multiple successors, we take the intersection of all of
1170 VEC (basic_block) * worklist;
1173 basic_block bprime, first;
1176 worklist = VEC_alloc (basic_block, 2);
1177 FOR_EACH_EDGE (e, ei, block->succs)
1178 VEC_safe_push (basic_block, worklist, e->dest);
1179 first = VEC_index (basic_block, worklist, 0);
1180 set_copy (ANTIC_OUT, ANTIC_IN (first));
1182 for (i = 1; VEC_iterate (basic_block, worklist, i, bprime); i++)
1184 node = ANTIC_OUT->head;
1188 value_set_node_t next = node->next;
1189 val = get_value_handle (node->expr);
1190 if (!set_contains_value (ANTIC_IN (bprime), val))
1191 set_remove (ANTIC_OUT, node->expr);
1195 VEC_free (basic_block, worklist);
1198 /* Generate ANTIC_OUT - TMP_GEN. */
1199 S = bitmap_set_subtract_from_value_set (ANTIC_OUT, TMP_GEN (block), false);
1201 /* Start ANTIC_IN with EXP_GEN - TMP_GEN */
1202 ANTIC_IN (block) = bitmap_set_subtract_from_value_set (EXP_GEN (block),
1206 /* Then union in the ANTIC_OUT - TMP_GEN values, to get ANTIC_OUT U
1207 EXP_GEN - TMP_GEN */
1208 for (node = S->head;
1212 value_insert_into_set (ANTIC_IN (block), node->expr);
1214 clean (ANTIC_IN (block));
1217 if (!set_equal (old, ANTIC_IN (block)))
1221 if (dump_file && (dump_flags & TDF_DETAILS))
1224 print_value_set (dump_file, ANTIC_OUT, "ANTIC_OUT", block->index);
1225 print_value_set (dump_file, ANTIC_IN (block), "ANTIC_IN", block->index);
1227 print_value_set (dump_file, S, "S", block->index);
1231 for (son = first_dom_son (CDI_POST_DOMINATORS, block);
1233 son = next_dom_son (CDI_POST_DOMINATORS, son))
1235 changed |= compute_antic_aux (son);
1240 /* Compute ANTIC sets. */
1243 compute_antic (void)
1245 bool changed = true;
1247 int num_iterations = 0;
1250 ANTIC_IN (bb) = set_new (true);
1251 gcc_assert (!(bb->flags & BB_VISITED));
1258 changed = compute_antic_aux (EXIT_BLOCK_PTR);
1262 bb->flags &= ~BB_VISITED;
1264 if (num_iterations > 2 && dump_file && (dump_flags & TDF_STATS))
1265 fprintf (dump_file, "compute_antic required %d iterations\n", num_iterations);
1269 /* Find a leader for an expression, or generate one using
1270 create_expression_by_pieces if it's ANTIC but
1272 BLOCK is the basic_block we are looking for leaders in.
1273 EXPR is the expression to find a leader or generate for.
1274 STMTS is the statement list to put the inserted expressions on.
1275 Returns the SSA_NAME of the LHS of the generated expression or the
1279 find_or_generate_expression (basic_block block, tree expr, tree stmts)
1282 genop = bitmap_find_leader (AVAIL_OUT (block), expr);
1283 /* Depending on the order we process DOM branches in, the value
1284 may not have propagated to all the dom children yet during
1285 this iteration. In this case, the value will always be in
1286 the NEW_SETS for us already, having been propagated from our
1289 genop = bitmap_find_leader (NEW_SETS (block), expr);
1290 /* If it's still NULL, see if it is a complex expression, and if
1291 so, generate it recursively, otherwise, abort, because it's
1295 genop = VALUE_HANDLE_EXPR_SET (expr)->head->expr;
1296 gcc_assert (UNARY_CLASS_P (genop)
1297 || BINARY_CLASS_P (genop)
1298 || REFERENCE_CLASS_P (genop));
1299 genop = create_expression_by_pieces (block, genop, stmts);
1305 /* Create an expression in pieces, so that we can handle very complex
1306 expressions that may be ANTIC, but not necessary GIMPLE.
1307 BLOCK is the basic block the expression will be inserted into,
1308 EXPR is the expression to insert (in value form)
1309 STMTS is a statement list to append the necessary insertions into.
1311 This function will abort if we hit some value that shouldn't be
1312 ANTIC but is (IE there is no leader for it, or its components).
1313 This function may also generate expressions that are themselves
1314 partially or fully redundant. Those that are will be either made
1315 fully redundant during the next iteration of insert (for partially
1316 redundant ones), or eliminated by eliminate (for fully redundant
1320 create_expression_by_pieces (basic_block block, tree expr, tree stmts)
1322 tree name = NULL_TREE;
1323 tree newexpr = NULL_TREE;
1326 switch (TREE_CODE_CLASS (TREE_CODE (expr)))
1330 tree_stmt_iterator tsi;
1331 tree genop1, genop2;
1333 tree op1 = TREE_OPERAND (expr, 0);
1334 tree op2 = TREE_OPERAND (expr, 1);
1335 genop1 = find_or_generate_expression (block, op1, stmts);
1336 genop2 = find_or_generate_expression (block, op2, stmts);
1337 temp = create_tmp_var (TREE_TYPE (expr), "pretmp");
1338 add_referenced_tmp_var (temp);
1339 newexpr = build (TREE_CODE (expr), TREE_TYPE (expr),
1341 newexpr = build (MODIFY_EXPR, TREE_TYPE (expr),
1343 name = make_ssa_name (temp, newexpr);
1344 TREE_OPERAND (newexpr, 0) = name;
1345 tsi = tsi_last (stmts);
1346 tsi_link_after (&tsi, newexpr, TSI_CONTINUE_LINKING);
1347 pre_stats.insertions++;
1352 tree_stmt_iterator tsi;
1355 tree op1 = TREE_OPERAND (expr, 0);
1356 genop1 = find_or_generate_expression (block, op1, stmts);
1357 temp = create_tmp_var (TREE_TYPE (expr), "pretmp");
1358 add_referenced_tmp_var (temp);
1359 newexpr = build (TREE_CODE (expr), TREE_TYPE (expr),
1361 newexpr = build (MODIFY_EXPR, TREE_TYPE (expr),
1363 name = make_ssa_name (temp, newexpr);
1364 TREE_OPERAND (newexpr, 0) = name;
1365 tsi = tsi_last (stmts);
1366 tsi_link_after (&tsi, newexpr, TSI_CONTINUE_LINKING);
1367 pre_stats.insertions++;
1375 v = get_value_handle (expr);
1376 vn_add (name, v, NULL);
1377 bitmap_insert_into_set (NEW_SETS (block), name);
1378 bitmap_value_insert_into_set (AVAIL_OUT (block), name);
1379 if (dump_file && (dump_flags & TDF_DETAILS))
1381 fprintf (dump_file, "Inserted ");
1382 print_generic_expr (dump_file, newexpr, 0);
1383 fprintf (dump_file, " in predecessor %d\n", block->index);
1388 /* Perform insertion of partially redundant values.
1389 For BLOCK, do the following:
1390 1. Propagate the NEW_SETS of the dominator into the current block.
1391 If the block has multiple predecessors,
1392 2a. Iterate over the ANTIC expressions for the block to see if
1393 any of them are partially redundant.
1394 2b. If so, insert them into the necessary predecessors to make
1395 the expression fully redundant.
1396 2c. Insert a new PHI merging the values of the predecessors.
1397 2d. Insert the new PHI, and the new expressions, into the
1399 3. Recursively call ourselves on the dominator children of BLOCK.
1403 insert_aux (basic_block block)
1406 bool new_stuff = false;
1411 dom = get_immediate_dominator (CDI_DOMINATORS, block);
1417 bitmap_set_t newset = NEW_SETS (dom);
1418 EXECUTE_IF_SET_IN_BITMAP (newset->expressions, 0, i, bi)
1420 bitmap_insert_into_set (NEW_SETS (block), ssa_name (i));
1421 bitmap_value_replace_in_set (AVAIL_OUT (block), ssa_name (i));
1423 if (EDGE_COUNT (block->preds) > 1)
1425 value_set_node_t node;
1426 for (node = ANTIC_IN (block)->head;
1430 if (BINARY_CLASS_P (node->expr)
1431 || UNARY_CLASS_P (node->expr))
1435 bool by_some = false;
1436 bool cant_insert = false;
1437 bool all_same = true;
1438 tree first_s = NULL;
1444 val = get_value_handle (node->expr);
1445 if (bitmap_set_contains_value (PHI_GEN (block), val))
1447 if (bitmap_set_contains_value (AVAIL_OUT (dom), val))
1449 if (dump_file && (dump_flags & TDF_DETAILS))
1450 fprintf (dump_file, "Found fully redundant value\n");
1454 avail = xcalloc (last_basic_block, sizeof (tree));
1455 FOR_EACH_EDGE (pred, ei, block->preds)
1460 /* This can happen in the very weird case
1461 that our fake infinite loop edges have caused a
1462 critical edge to appear. */
1463 if (EDGE_CRITICAL_P (pred))
1469 eprime = phi_translate (node->expr,
1473 /* eprime will generally only be NULL if the
1474 value of the expression, translated
1475 through the PHI for this predecessor, is
1476 undefined. If that is the case, we can't
1477 make the expression fully redundant,
1478 because its value is undefined along a
1479 predecessor path. We can thus break out
1480 early because it doesn't matter what the
1481 rest of the results are. */
1488 vprime = get_value_handle (eprime);
1489 gcc_assert (vprime);
1490 edoubleprime = bitmap_find_leader (AVAIL_OUT (bprime),
1492 if (edoubleprime == NULL)
1494 avail[bprime->index] = eprime;
1499 avail[bprime->index] = edoubleprime;
1501 if (first_s == NULL)
1502 first_s = edoubleprime;
1503 else if (first_s != edoubleprime)
1505 gcc_assert (first_s == edoubleprime
1507 (first_s, edoubleprime, 0));
1510 /* If we can insert it, it's not the same value
1511 already existing along every predecessor, and
1512 it's defined by some predecessor, it is
1513 partially redundant. */
1514 if (!cant_insert && !all_same && by_some)
1516 tree type = TREE_TYPE (avail[EDGE_PRED (block, 0)->src->index]);
1518 if (dump_file && (dump_flags & TDF_DETAILS))
1520 fprintf (dump_file, "Found partial redundancy for expression ");
1521 print_generic_expr (dump_file, node->expr, 0);
1522 fprintf (dump_file, "\n");
1525 /* Make the necessary insertions. */
1526 FOR_EACH_EDGE (pred, ei, block->preds)
1528 tree stmts = alloc_stmt_list ();
1531 eprime = avail[bprime->index];
1532 if (BINARY_CLASS_P (eprime)
1533 || UNARY_CLASS_P (eprime))
1535 builtexpr = create_expression_by_pieces (bprime,
1538 bsi_insert_on_edge (pred, stmts);
1539 avail[bprime->index] = builtexpr;
1542 /* Now build a phi for the new variable. */
1543 temp = create_tmp_var (type, "prephitmp");
1544 add_referenced_tmp_var (temp);
1545 temp = create_phi_node (temp, block);
1546 vn_add (PHI_RESULT (temp), val, NULL);
1549 if (!set_contains_value (AVAIL_OUT (block), val))
1550 insert_into_set (AVAIL_OUT (block),
1554 bitmap_value_replace_in_set (AVAIL_OUT (block),
1556 FOR_EACH_EDGE (pred, ei, block->preds)
1558 add_phi_arg (temp, avail[pred->src->index],
1561 if (dump_file && (dump_flags & TDF_DETAILS))
1563 fprintf (dump_file, "Created phi ");
1564 print_generic_expr (dump_file, temp, 0);
1565 fprintf (dump_file, " in block %d\n", block->index);
1569 bitmap_insert_into_set (NEW_SETS (block),
1571 bitmap_insert_into_set (PHI_GEN (block),
1581 for (son = first_dom_son (CDI_DOMINATORS, block);
1583 son = next_dom_son (CDI_DOMINATORS, son))
1585 new_stuff |= insert_aux (son);
1591 /* Perform insertion of partially redundant values. */
1596 bool new_stuff = true;
1598 int num_iterations = 0;
1601 NEW_SETS (bb) = bitmap_set_new ();
1607 new_stuff = insert_aux (ENTRY_BLOCK_PTR);
1609 if (num_iterations > 2 && dump_file && (dump_flags & TDF_STATS))
1610 fprintf (dump_file, "insert required %d iterations\n", num_iterations);
1614 /* Return true if VAR is an SSA variable with no defining statement in
1615 this procedure, *AND* isn't a live-on-entry parameter. */
1618 is_undefined_value (tree expr)
1620 return (TREE_CODE (expr) == SSA_NAME
1621 && IS_EMPTY_STMT (SSA_NAME_DEF_STMT (expr))
1622 /* PARM_DECLs and hard registers are always defined. */
1623 && TREE_CODE (SSA_NAME_VAR (expr)) != PARM_DECL);
1627 /* Given an SSA variable VAR and an expression EXPR, compute the value
1628 number for EXPR and create a value handle (VAL) for it. If VAR and
1629 EXPR are not the same, associate VAL with VAR. Finally, add VAR to
1630 S1 and its value handle to S2.
1632 VUSES represent the virtual use operands associated with EXPR (if
1633 any). They are used when computing the hash value for EXPR. */
1636 add_to_sets (tree var, tree expr, vuse_optype vuses, bitmap_set_t s1,
1639 tree val = vn_lookup_or_add (expr, vuses);
1641 /* VAR and EXPR may be the same when processing statements for which
1642 we are not computing value numbers (e.g., non-assignments, or
1643 statements that make aliased stores). In those cases, we are
1644 only interested in making VAR available as its own value. */
1646 vn_add (var, val, NULL);
1648 bitmap_insert_into_set (s1, var);
1649 bitmap_value_insert_into_set (s2, var);
1653 /* Given a unary or binary expression EXPR, create and return a new
1654 expression with the same structure as EXPR but with its operands
1655 replaced with the value handles of each of the operands of EXPR.
1656 Insert EXPR's operands into the EXP_GEN set for BLOCK.
1658 VUSES represent the virtual use operands associated with EXPR (if
1659 any). They are used when computing the hash value for EXPR. */
1662 create_value_expr_from (tree expr, basic_block block, vuse_optype vuses)
1665 enum tree_code code = TREE_CODE (expr);
1668 gcc_assert (TREE_CODE_CLASS (code) == tcc_unary
1669 || TREE_CODE_CLASS (code) == tcc_binary
1670 || TREE_CODE_CLASS (code) == tcc_reference);
1672 if (TREE_CODE_CLASS (code) == tcc_unary)
1673 vexpr = pool_alloc (unary_node_pool);
1674 else if (TREE_CODE_CLASS (code) == tcc_reference)
1675 vexpr = pool_alloc (reference_node_pool);
1677 vexpr = pool_alloc (binary_node_pool);
1679 memcpy (vexpr, expr, tree_size (expr));
1681 for (i = 0; i < TREE_CODE_LENGTH (code); i++)
1683 tree op = TREE_OPERAND (expr, i);
1686 tree val = vn_lookup_or_add (op, vuses);
1687 if (!is_undefined_value (op))
1688 value_insert_into_set (EXP_GEN (block), op);
1689 if (TREE_CODE (val) == VALUE_HANDLE)
1690 TREE_TYPE (val) = TREE_TYPE (TREE_OPERAND (vexpr, i));
1691 TREE_OPERAND (vexpr, i) = val;
1699 /* Compute the AVAIL set for BLOCK.
1700 This function performs value numbering of the statements in BLOCK.
1701 The AVAIL sets are built from information we glean while doing this
1702 value numbering, since the AVAIL sets contain only one entry per
1705 AVAIL_IN[BLOCK] = AVAIL_OUT[dom(BLOCK)].
1706 AVAIL_OUT[BLOCK] = AVAIL_IN[BLOCK] U PHI_GEN[BLOCK] U TMP_GEN[BLOCK]. */
1709 compute_avail (basic_block block)
1713 /* For arguments with default definitions, we pretend they are
1714 defined in the entry block. */
1715 if (block == ENTRY_BLOCK_PTR)
1718 for (param = DECL_ARGUMENTS (current_function_decl);
1720 param = TREE_CHAIN (param))
1722 if (default_def (param) != NULL)
1725 tree def = default_def (param);
1726 val = vn_lookup_or_add (def, NULL);
1727 bitmap_insert_into_set (TMP_GEN (block), def);
1728 bitmap_value_insert_into_set (AVAIL_OUT (block), def);
1734 block_stmt_iterator bsi;
1738 /* Initially, the set of available values in BLOCK is that of
1739 its immediate dominator. */
1740 dom = get_immediate_dominator (CDI_DOMINATORS, block);
1742 bitmap_set_copy (AVAIL_OUT (block), AVAIL_OUT (dom));
1744 /* Generate values for PHI nodes. */
1745 for (phi = phi_nodes (block); phi; phi = PHI_CHAIN (phi))
1746 /* We have no need for virtual phis, as they don't represent
1747 actual computations. */
1748 if (is_gimple_reg (PHI_RESULT (phi)))
1749 add_to_sets (PHI_RESULT (phi), PHI_RESULT (phi), NULL,
1750 PHI_GEN (block), AVAIL_OUT (block));
1752 /* Now compute value numbers and populate value sets with all
1753 the expressions computed in BLOCK. */
1754 for (bsi = bsi_start (block); !bsi_end_p (bsi); bsi_next (&bsi))
1759 stmt = bsi_stmt (bsi);
1760 ann = stmt_ann (stmt);
1761 get_stmt_operands (stmt);
1763 /* We are only interested in assignments of the form
1764 X_i = EXPR, where EXPR represents an "interesting"
1765 computation, it has no volatile operands and X_i
1766 doesn't flow through an abnormal edge. */
1767 if (TREE_CODE (stmt) == MODIFY_EXPR
1768 && !ann->has_volatile_ops
1769 && TREE_CODE (TREE_OPERAND (stmt, 0)) == SSA_NAME
1770 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (TREE_OPERAND (stmt, 0)))
1772 tree lhs = TREE_OPERAND (stmt, 0);
1773 tree rhs = TREE_OPERAND (stmt, 1);
1774 vuse_optype vuses = STMT_VUSE_OPS (stmt);
1776 STRIP_USELESS_TYPE_CONVERSION (rhs);
1777 if (TREE_CODE (rhs) == SSA_NAME
1778 || is_gimple_min_invariant (rhs))
1780 /* Compute a value number for the RHS of the statement
1781 and add its value to the AVAIL_OUT set for the block.
1782 Add the LHS to TMP_GEN. */
1783 add_to_sets (lhs, rhs, vuses, TMP_GEN (block),
1786 if (TREE_CODE (rhs) == SSA_NAME
1787 && !is_undefined_value (rhs))
1788 value_insert_into_set (EXP_GEN (block), rhs);
1791 else if (UNARY_CLASS_P (rhs) || BINARY_CLASS_P (rhs)
1792 || TREE_CODE (rhs) == INDIRECT_REF)
1794 /* For binary, unary, and reference expressions,
1795 create a duplicate expression with the operands
1796 replaced with the value handles of the original
1798 tree newt = create_value_expr_from (rhs, block, vuses);
1799 add_to_sets (lhs, newt, vuses, TMP_GEN (block),
1801 value_insert_into_set (EXP_GEN (block), newt);
1806 /* For any other statement that we don't recognize, simply
1807 make the names generated by the statement available in
1808 AVAIL_OUT and TMP_GEN. */
1809 for (j = 0; j < NUM_DEFS (STMT_DEF_OPS (stmt)); j++)
1811 tree def = DEF_OP (STMT_DEF_OPS (stmt), j);
1812 add_to_sets (def, def, NULL, TMP_GEN (block),
1816 for (j = 0; j < NUM_USES (STMT_USE_OPS (stmt)); j++)
1818 tree use = USE_OP (STMT_USE_OPS (stmt), j);
1819 add_to_sets (use, use, NULL, TMP_GEN (block),
1825 /* Compute available sets for the dominator children of BLOCK. */
1826 for (son = first_dom_son (CDI_DOMINATORS, block);
1828 son = next_dom_son (CDI_DOMINATORS, son))
1829 compute_avail (son);
1833 /* Eliminate fully redundant computations. */
1842 block_stmt_iterator i;
1844 for (i = bsi_start (b); !bsi_end_p (i); bsi_next (&i))
1846 tree stmt = bsi_stmt (i);
1848 /* Lookup the RHS of the expression, see if we have an
1849 available computation for it. If so, replace the RHS with
1850 the available computation. */
1851 if (TREE_CODE (stmt) == MODIFY_EXPR
1852 && TREE_CODE (TREE_OPERAND (stmt, 0)) == SSA_NAME
1853 && TREE_CODE (TREE_OPERAND (stmt ,1)) != SSA_NAME
1854 && !is_gimple_min_invariant (TREE_OPERAND (stmt, 1))
1855 && !stmt_ann (stmt)->has_volatile_ops)
1857 tree lhs = TREE_OPERAND (stmt, 0);
1858 tree *rhs_p = &TREE_OPERAND (stmt, 1);
1861 sprime = bitmap_find_leader (AVAIL_OUT (b),
1862 vn_lookup (lhs, NULL));
1865 && (TREE_CODE (*rhs_p) != SSA_NAME
1866 || may_propagate_copy (*rhs_p, sprime)))
1868 gcc_assert (sprime != *rhs_p);
1870 if (dump_file && (dump_flags & TDF_DETAILS))
1872 fprintf (dump_file, "Replaced ");
1873 print_generic_expr (dump_file, *rhs_p, 0);
1874 fprintf (dump_file, " with ");
1875 print_generic_expr (dump_file, sprime, 0);
1876 fprintf (dump_file, " in ");
1877 print_generic_stmt (dump_file, stmt, 0);
1879 pre_stats.eliminations++;
1880 propagate_tree_value (rhs_p, sprime);
1883 /* If we removed EH side effects from the statement, clean
1884 its EH information. */
1885 if (maybe_clean_eh_stmt (stmt))
1887 bitmap_set_bit (need_eh_cleanup,
1888 bb_for_stmt (stmt)->index);
1889 if (dump_file && (dump_flags & TDF_DETAILS))
1890 fprintf (dump_file, " Removed EH side effects.\n");
1899 /* Initialize data structures used by PRE. */
1906 connect_infinite_loops_to_exit ();
1908 memset (&pre_stats, 0, sizeof (pre_stats));
1910 /* If block 0 has more than one predecessor, it means that its PHI
1911 nodes will have arguments coming from block -1. This creates
1912 problems for several places in PRE that keep local arrays indexed
1913 by block number. To prevent this, we split the edge coming from
1914 ENTRY_BLOCK_PTR (FIXME, if ENTRY_BLOCK_PTR had an index number
1915 different than -1 we wouldn't have to hack this. tree-ssa-dce.c
1916 needs a similar change). */
1917 if (EDGE_COUNT (EDGE_SUCC (ENTRY_BLOCK_PTR, 0)->dest->preds) > 1)
1918 if (!(EDGE_SUCC (ENTRY_BLOCK_PTR, 0)->flags & EDGE_ABNORMAL))
1919 split_edge (EDGE_SUCC (ENTRY_BLOCK_PTR, 0));
1922 bb->aux = xcalloc (1, sizeof (struct bb_value_sets));
1924 bitmap_obstack_initialize (&grand_bitmap_obstack);
1925 phi_translate_table = htab_create (511, expr_pred_trans_hash,
1926 expr_pred_trans_eq, free);
1927 value_set_pool = create_alloc_pool ("Value sets",
1928 sizeof (struct value_set), 30);
1929 bitmap_set_pool = create_alloc_pool ("Bitmap sets",
1930 sizeof (struct bitmap_set), 30);
1931 value_set_node_pool = create_alloc_pool ("Value set nodes",
1932 sizeof (struct value_set_node), 30);
1933 calculate_dominance_info (CDI_POST_DOMINATORS);
1934 calculate_dominance_info (CDI_DOMINATORS);
1935 binary_node_pool = create_alloc_pool ("Binary tree nodes",
1936 tree_code_size (PLUS_EXPR), 30);
1937 unary_node_pool = create_alloc_pool ("Unary tree nodes",
1938 tree_code_size (NEGATE_EXPR), 30);
1939 reference_node_pool = create_alloc_pool ("Reference tree nodes",
1940 tree_code_size (ARRAY_REF), 30);
1943 EXP_GEN (bb) = set_new (true);
1944 PHI_GEN (bb) = bitmap_set_new ();
1945 TMP_GEN (bb) = bitmap_set_new ();
1946 AVAIL_OUT (bb) = bitmap_set_new ();
1949 need_eh_cleanup = BITMAP_XMALLOC ();
1953 /* Deallocate data structures used by PRE. */
1961 bsi_commit_edge_inserts ();
1963 bitmap_obstack_release (&grand_bitmap_obstack);
1964 free_alloc_pool (value_set_pool);
1965 free_alloc_pool (bitmap_set_pool);
1966 free_alloc_pool (value_set_node_pool);
1967 free_alloc_pool (binary_node_pool);
1968 free_alloc_pool (reference_node_pool);
1969 free_alloc_pool (unary_node_pool);
1970 htab_delete (phi_translate_table);
1971 remove_fake_exit_edges ();
1979 free_dominance_info (CDI_POST_DOMINATORS);
1982 if (!bitmap_empty_p (need_eh_cleanup))
1984 tree_purge_all_dead_eh_edges (need_eh_cleanup);
1985 cleanup_tree_cfg ();
1988 BITMAP_XFREE (need_eh_cleanup);
1990 /* Wipe out pointers to VALUE_HANDLEs. In the not terribly distant
1991 future we will want them to be persistent though. */
1992 for (i = 0; i < num_ssa_names; i++)
1994 tree name = ssa_name (i);
1999 if (SSA_NAME_VALUE (name)
2000 && TREE_CODE (SSA_NAME_VALUE (name)) == VALUE_HANDLE)
2001 SSA_NAME_VALUE (name) = NULL;
2006 /* Main entry point to the SSA-PRE pass. DO_FRE is true if the caller
2007 only wants to do full redundancy elimination. */
2010 execute_pre (bool do_fre)
2014 /* Collect and value number expressions computed in each basic
2016 compute_avail (ENTRY_BLOCK_PTR);
2018 if (dump_file && (dump_flags & TDF_DETAILS))
2024 print_value_set (dump_file, EXP_GEN (bb), "exp_gen", bb->index);
2025 bitmap_print_value_set (dump_file, TMP_GEN (bb), "tmp_gen",
2027 bitmap_print_value_set (dump_file, AVAIL_OUT (bb), "avail_out",
2032 /* Insert can get quite slow on an incredibly large number of basic
2033 blocks due to some quadratic behavior. Until this behavior is
2034 fixed, don't run it when he have an incredibly large number of
2035 bb's. If we aren't going to run insert, there is no point in
2036 computing ANTIC, either, even though it's plenty fast. */
2037 if (!do_fre && n_basic_blocks < 4000)
2043 /* Remove all the redundant expressions. */
2046 if (dump_file && (dump_flags & TDF_STATS))
2048 fprintf (dump_file, "Insertions:%d\n", pre_stats.insertions);
2049 fprintf (dump_file, "New PHIs:%d\n", pre_stats.phis);
2050 fprintf (dump_file, "Eliminated:%d\n", pre_stats.eliminations);
2057 /* Gate and execute functions for PRE. */
2062 execute_pre (false);
2068 return flag_tree_pre != 0;
2071 struct tree_opt_pass pass_pre =
2074 gate_pre, /* gate */
2075 do_pre, /* execute */
2078 0, /* static_pass_number */
2079 TV_TREE_PRE, /* tv_id */
2080 PROP_no_crit_edges | PROP_cfg
2081 | PROP_ssa | PROP_alias, /* properties_required */
2082 0, /* properties_provided */
2083 0, /* properties_destroyed */
2084 0, /* todo_flags_start */
2085 TODO_dump_func | TODO_ggc_collect | TODO_verify_ssa, /* todo_flags_finish */
2090 /* Gate and execute functions for FRE. */
2101 return flag_tree_fre != 0;
2104 struct tree_opt_pass pass_fre =
2107 gate_fre, /* gate */
2108 do_fre, /* execute */
2111 0, /* static_pass_number */
2112 TV_TREE_FRE, /* tv_id */
2113 PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
2114 0, /* properties_provided */
2115 0, /* properties_destroyed */
2116 0, /* todo_flags_start */
2117 TODO_dump_func | TODO_ggc_collect | TODO_verify_ssa, /* todo_flags_finish */