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 struct 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
)
466 set
->values
= BITMAP_OBSTACK_ALLOC (&grand_bitmap_obstack
);
467 bitmap_clear (set
->values
);
470 bitmap_set_bit (set
->values
, VALUE_HANDLE_ID (v
));
474 /* Create a new bitmap set and return it. */
477 bitmap_set_new (void)
479 bitmap_set_t ret
= pool_alloc (bitmap_set_pool
);
480 ret
->expressions
= BITMAP_OBSTACK_ALLOC (&grand_bitmap_obstack
);
481 ret
->values
= BITMAP_OBSTACK_ALLOC (&grand_bitmap_obstack
);
482 bitmap_clear (ret
->expressions
);
483 bitmap_clear (ret
->values
);
487 /* Create a new set. */
490 set_new (bool indexed
)
493 ret
= pool_alloc (value_set_pool
);
494 ret
->head
= ret
->tail
= NULL
;
496 ret
->indexed
= indexed
;
501 /* Insert an expression EXPR into a bitmapped set. */
504 bitmap_insert_into_set (bitmap_set_t set
, tree expr
)
507 /* XXX: For now, we only let SSA_NAMES into the bitmap sets. */
508 gcc_assert (TREE_CODE (expr
) == SSA_NAME
);
509 val
= get_value_handle (expr
);
512 if (!is_gimple_min_invariant (val
))
513 bitmap_set_bit (set
->values
, VALUE_HANDLE_ID (val
));
514 bitmap_set_bit (set
->expressions
, SSA_NAME_VERSION (expr
));
517 /* Insert EXPR into SET. */
520 insert_into_set (value_set_t set
, tree expr
)
522 value_set_node_t newnode
= pool_alloc (value_set_node_pool
);
523 tree val
= get_value_handle (expr
);
526 if (is_gimple_min_invariant (val
))
529 /* For indexed sets, insert the value into the set value bitmap.
530 For all sets, add it to the linked list and increment the list
533 value_insert_into_set_bitmap (set
, val
);
535 newnode
->next
= NULL
;
536 newnode
->expr
= expr
;
538 if (set
->head
== NULL
)
540 set
->head
= set
->tail
= newnode
;
544 set
->tail
->next
= newnode
;
549 /* Copy a bitmapped set ORIG, into bitmapped set DEST. */
552 bitmap_set_copy (bitmap_set_t dest
, bitmap_set_t orig
)
554 bitmap_copy (dest
->expressions
, orig
->expressions
);
555 bitmap_copy (dest
->values
, orig
->values
);
558 /* Copy the set ORIG to the set DEST. */
561 set_copy (value_set_t dest
, value_set_t orig
)
563 value_set_node_t node
;
565 if (!orig
|| !orig
->head
)
568 for (node
= orig
->head
;
572 insert_into_set (dest
, node
->expr
);
576 /* Remove EXPR from SET. */
579 set_remove (value_set_t set
, tree expr
)
581 value_set_node_t node
, prev
;
583 /* Remove the value of EXPR from the bitmap, decrement the set
584 length, and remove it from the actual double linked list. */
585 value_remove_from_set_bitmap (set
, get_value_handle (expr
));
588 for (node
= set
->head
;
590 prev
= node
, node
= node
->next
)
592 if (node
->expr
== expr
)
595 set
->head
= node
->next
;
597 prev
->next
= node
->next
;
599 if (node
== set
->tail
)
601 pool_free (value_set_node_pool
, node
);
607 /* Return true if SET contains the value VAL. */
610 set_contains_value (value_set_t set
, tree val
)
612 /* All constants are in every set. */
613 if (is_gimple_min_invariant (val
))
616 if (set
->length
== 0)
619 return value_exists_in_set_bitmap (set
, val
);
622 /* Return true if bitmapped set SET contains the expression EXPR. */
624 bitmap_set_contains (bitmap_set_t set
, tree expr
)
626 /* All constants are in every set. */
627 if (is_gimple_min_invariant (get_value_handle (expr
)))
630 /* XXX: Bitmapped sets only contain SSA_NAME's for now. */
631 if (TREE_CODE (expr
) != SSA_NAME
)
633 return bitmap_bit_p (set
->expressions
, SSA_NAME_VERSION (expr
));
637 /* Return true if bitmapped set SET contains the value VAL. */
640 bitmap_set_contains_value (bitmap_set_t set
, tree val
)
642 if (is_gimple_min_invariant (val
))
644 return bitmap_bit_p (set
->values
, VALUE_HANDLE_ID (val
));
647 /* Replace an instance of value LOOKFOR with expression EXPR in SET. */
650 bitmap_set_replace_value (bitmap_set_t set
, tree lookfor
, tree expr
)
653 value_set_node_t node
;
654 if (is_gimple_min_invariant (lookfor
))
656 if (!bitmap_set_contains_value (set
, lookfor
))
658 /* The number of expressions having a given value is usually
659 significantly less than the total number of expressions in SET.
660 Thus, rather than check, for each expression in SET, whether it
661 has the value LOOKFOR, we walk the reverse mapping that tells us
662 what expressions have a given value, and see if any of those
663 expressions are in our set. For large testcases, this is about
664 5-10x faster than walking the bitmap. If this is somehow a
665 significant lose for some cases, we can choose which set to walk
666 based on the set size. */
667 exprset
= VALUE_HANDLE_EXPR_SET (lookfor
);
668 for (node
= exprset
->head
; node
; node
= node
->next
)
670 if (TREE_CODE (node
->expr
) == SSA_NAME
)
672 if (bitmap_bit_p (set
->expressions
, SSA_NAME_VERSION (node
->expr
)))
674 bitmap_clear_bit (set
->expressions
, SSA_NAME_VERSION (node
->expr
));
675 bitmap_set_bit (set
->expressions
, SSA_NAME_VERSION (expr
));
682 /* Subtract bitmapped set B from value set A, and return the new set. */
685 bitmap_set_subtract_from_value_set (value_set_t a
, bitmap_set_t b
,
688 value_set_t ret
= set_new (indexed
);
689 value_set_node_t node
;
694 if (!bitmap_set_contains (b
, node
->expr
))
695 insert_into_set (ret
, node
->expr
);
700 /* Return true if two sets are equal. */
703 set_equal (value_set_t a
, value_set_t b
)
705 value_set_node_t node
;
707 if (a
->length
!= b
->length
)
713 if (!set_contains_value (b
, get_value_handle (node
->expr
)))
719 /* Replace an instance of EXPR's VALUE with EXPR in SET. */
722 bitmap_value_replace_in_set (bitmap_set_t set
, tree expr
)
724 tree val
= get_value_handle (expr
);
725 bitmap_set_replace_value (set
, val
, expr
);
728 /* Insert EXPR into SET if EXPR's value is not already present in
732 bitmap_value_insert_into_set (bitmap_set_t set
, tree expr
)
734 tree val
= get_value_handle (expr
);
736 if (is_gimple_min_invariant (val
))
739 if (!bitmap_set_contains_value (set
, val
))
740 bitmap_insert_into_set (set
, expr
);
743 /* Insert the value for EXPR into SET, if it doesn't exist already. */
746 value_insert_into_set (value_set_t set
, tree expr
)
748 tree val
= get_value_handle (expr
);
750 /* Constant and invariant values exist everywhere, and thus,
751 actually keeping them in the sets is pointless. */
752 if (is_gimple_min_invariant (val
))
755 if (!set_contains_value (set
, val
))
756 insert_into_set (set
, expr
);
760 /* Print out SET to OUTFILE. */
763 bitmap_print_value_set (FILE *outfile
, bitmap_set_t set
,
764 const char *setname
, int blockindex
)
766 fprintf (outfile
, "%s[%d] := { ", setname
, blockindex
);
770 EXECUTE_IF_SET_IN_BITMAP (set
->expressions
, 0, i
,
772 print_generic_expr (outfile
, ssa_name (i
), 0);
774 fprintf (outfile
, " (");
775 print_generic_expr (outfile
, get_value_handle (ssa_name (i
)), 0);
776 fprintf (outfile
, ") ");
777 if (bitmap_last_set_bit (set
->expressions
) != i
)
778 fprintf (outfile
, ", ");
781 fprintf (outfile
, " }\n");
783 /* Print out the value_set SET to OUTFILE. */
786 print_value_set (FILE *outfile
, value_set_t set
,
787 const char *setname
, int blockindex
)
789 value_set_node_t node
;
790 fprintf (outfile
, "%s[%d] := { ", setname
, blockindex
);
793 for (node
= set
->head
;
797 print_generic_expr (outfile
, node
->expr
, 0);
799 fprintf (outfile
, " (");
800 print_generic_expr (outfile
, get_value_handle (node
->expr
), 0);
801 fprintf (outfile
, ") ");
804 fprintf (outfile
, ", ");
808 fprintf (outfile
, " }\n");
811 /* Print out the expressions that have VAL to OUTFILE. */
814 print_value_expressions (FILE *outfile
, tree val
)
816 if (VALUE_HANDLE_EXPR_SET (val
))
819 sprintf (s
, "VH.%04d", VALUE_HANDLE_ID (val
));
820 print_value_set (outfile
, VALUE_HANDLE_EXPR_SET (val
), s
, 0);
826 debug_value_expressions (tree val
)
828 print_value_expressions (stderr
, val
);
832 void debug_value_set (value_set_t
, const char *, int);
835 debug_value_set (value_set_t set
, const char *setname
, int blockindex
)
837 print_value_set (stderr
, set
, setname
, blockindex
);
840 /* Translate EXPR using phis in PHIBLOCK, so that it has the values of
841 the phis in PRED. Return NULL if we can't find a leader for each
842 part of the translated expression. */
845 phi_translate (tree expr
, value_set_t set
, basic_block pred
,
846 basic_block phiblock
)
848 tree phitrans
= NULL
;
854 if (is_gimple_min_invariant (expr
))
857 /* Phi translations of a given expression don't change, */
858 phitrans
= phi_trans_lookup (expr
, pred
);
862 switch (TREE_CODE_CLASS (TREE_CODE (expr
)))
865 /* XXX: Until we have PRE of loads working, none will be ANTIC. */
870 tree oldop1
= TREE_OPERAND (expr
, 0);
871 tree oldop2
= TREE_OPERAND (expr
, 1);
876 newop1
= phi_translate (find_leader (set
, oldop1
),
877 set
, pred
, phiblock
);
880 newop2
= phi_translate (find_leader (set
, oldop2
),
881 set
, pred
, phiblock
);
884 if (newop1
!= oldop1
|| newop2
!= oldop2
)
886 newexpr
= pool_alloc (binary_node_pool
);
887 memcpy (newexpr
, expr
, tree_size (expr
));
888 create_tree_ann (newexpr
);
889 TREE_OPERAND (newexpr
, 0) = newop1
== oldop1
? oldop1
: get_value_handle (newop1
);
890 TREE_OPERAND (newexpr
, 1) = newop2
== oldop2
? oldop2
: get_value_handle (newop2
);
891 vn_lookup_or_add (newexpr
, NULL
);
893 phi_trans_add (oldexpr
, newexpr
, pred
);
900 tree oldop1
= TREE_OPERAND (expr
, 0);
904 newop1
= phi_translate (find_leader (set
, oldop1
),
905 set
, pred
, phiblock
);
908 if (newop1
!= oldop1
)
910 newexpr
= pool_alloc (unary_node_pool
);
911 memcpy (newexpr
, expr
, tree_size (expr
));
912 create_tree_ann (newexpr
);
913 TREE_OPERAND (newexpr
, 0) = get_value_handle (newop1
);
914 vn_lookup_or_add (newexpr
, NULL
);
916 phi_trans_add (oldexpr
, newexpr
, pred
);
921 case tcc_exceptional
:
925 gcc_assert (TREE_CODE (expr
) == SSA_NAME
);
926 if (TREE_CODE (SSA_NAME_DEF_STMT (expr
)) == PHI_NODE
)
927 phi
= SSA_NAME_DEF_STMT (expr
);
931 for (i
= 0; i
< PHI_NUM_ARGS (phi
); i
++)
932 if (PHI_ARG_EDGE (phi
, i
)->src
== pred
)
935 if (is_undefined_value (PHI_ARG_DEF (phi
, i
)))
937 val
= vn_lookup_or_add (PHI_ARG_DEF (phi
, i
), NULL
);
938 return PHI_ARG_DEF (phi
, i
);
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 /* Compute the ANTIC set for BLOCK.
1103 ANTIC_OUT[BLOCK] = intersection of ANTIC_IN[b] for all succ(BLOCK), if
1105 ANTIC_OUT[BLOCK] = phi_translate (ANTIC_IN[succ(BLOCK)]) if
1108 ANTIC_IN[BLOCK] = clean(ANTIC_OUT[BLOCK] U EXP_GEN[BLOCK] -
1111 Iterate until fixpointed.
1113 XXX: It would be nice to either write a set_clear, and use it for
1114 antic_out, or to mark the antic_out set as deleted at the end
1115 of this routine, so that the pool can hand the same memory back out
1116 again for the next antic_out. */
1120 compute_antic_aux (basic_block block
)
1124 bool changed
= false;
1125 value_set_t S
, old
, ANTIC_OUT
;
1126 value_set_node_t node
;
1128 ANTIC_OUT
= S
= NULL
;
1129 /* If any edges from predecessors are abnormal, antic_in is empty, so
1130 punt. Remember that the block has an incoming abnormal edge by
1131 setting the BB_VISITED flag. */
1132 if (! (block
->flags
& BB_VISITED
))
1134 for (e
= block
->pred
; e
; e
= e
->pred_next
)
1135 if (e
->flags
& EDGE_ABNORMAL
)
1137 block
->flags
|= BB_VISITED
;
1141 if (block
->flags
& BB_VISITED
)
1148 old
= set_new (false);
1149 set_copy (old
, ANTIC_IN (block
));
1150 ANTIC_OUT
= set_new (true);
1152 /* If the block has no successors, ANTIC_OUT is empty, because it is
1154 if (block
->succ
== NULL
);
1156 /* If we have one successor, we could have some phi nodes to
1157 translate through. */
1158 else if (block
->succ
->succ_next
== NULL
)
1160 phi_translate_set (ANTIC_OUT
, ANTIC_IN(block
->succ
->dest
),
1161 block
, block
->succ
->dest
);
1163 /* If we have multiple successors, we take the intersection of all of
1167 varray_type worklist
;
1170 basic_block bprime
, first
;
1172 VARRAY_BB_INIT (worklist
, 1, "succ");
1176 VARRAY_PUSH_BB (worklist
, e
->dest
);
1179 first
= VARRAY_BB (worklist
, 0);
1180 set_copy (ANTIC_OUT
, ANTIC_IN (first
));
1182 for (i
= 1; i
< VARRAY_ACTIVE_SIZE (worklist
); i
++)
1184 bprime
= VARRAY_BB (worklist
, i
);
1185 node
= ANTIC_OUT
->head
;
1189 value_set_node_t next
= node
->next
;
1190 val
= get_value_handle (node
->expr
);
1191 if (!set_contains_value (ANTIC_IN (bprime
), val
))
1192 set_remove (ANTIC_OUT
, node
->expr
);
1196 VARRAY_CLEAR (worklist
);
1199 /* Generate ANTIC_OUT - TMP_GEN */
1200 S
= bitmap_set_subtract_from_value_set (ANTIC_OUT
, TMP_GEN (block
), false);
1202 /* Start ANTIC_IN with EXP_GEN - TMP_GEN */
1203 ANTIC_IN (block
) = bitmap_set_subtract_from_value_set (EXP_GEN (block
),
1207 /* Then union in the ANTIC_OUT - TMP_GEN values, to get ANTIC_OUT U
1208 EXP_GEN - TMP_GEN */
1209 for (node
= S
->head
;
1213 value_insert_into_set (ANTIC_IN (block
), node
->expr
);
1215 clean (ANTIC_IN (block
));
1218 if (!set_equal (old
, ANTIC_IN (block
)))
1222 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1225 print_value_set (dump_file
, ANTIC_OUT
, "ANTIC_OUT", block
->index
);
1226 print_value_set (dump_file
, ANTIC_IN (block
), "ANTIC_IN", block
->index
);
1228 print_value_set (dump_file
, S
, "S", block
->index
);
1232 for (son
= first_dom_son (CDI_POST_DOMINATORS
, block
);
1234 son
= next_dom_son (CDI_POST_DOMINATORS
, son
))
1236 changed
|= compute_antic_aux (son
);
1241 /* Compute ANTIC sets. */
1244 compute_antic (void)
1246 bool changed
= true;
1248 int num_iterations
= 0;
1251 ANTIC_IN (bb
) = set_new (true);
1252 gcc_assert (!(bb
->flags
& BB_VISITED
));
1259 changed
= compute_antic_aux (EXIT_BLOCK_PTR
);
1263 bb
->flags
&= ~BB_VISITED
;
1265 if (num_iterations
> 2 && dump_file
&& (dump_flags
& TDF_STATS
))
1266 fprintf (dump_file
, "compute_antic required %d iterations\n", num_iterations
);
1270 /* Find a leader for an expression, or generate one using
1271 create_expression_by_pieces if it's ANTIC but
1273 BLOCK is the basic_block we are looking for leaders in.
1274 EXPR is the expression to find a leader or generate for.
1275 STMTS is the statement list to put the inserted expressions on.
1276 Returns the SSA_NAME of the LHS of the generated expression or the
1280 find_or_generate_expression (basic_block block
, tree expr
, tree stmts
)
1283 genop
= bitmap_find_leader (AVAIL_OUT (block
), expr
);
1284 /* Depending on the order we process DOM branches in, the value
1285 may not have propagated to all the dom children yet during
1286 this iteration. In this case, the value will always be in
1287 the NEW_SETS for us already, having been propagated from our
1290 genop
= bitmap_find_leader (NEW_SETS (block
), expr
);
1291 /* If it's still NULL, see if it is a complex expression, and if
1292 so, generate it recursively, otherwise, abort, because it's
1296 genop
= VALUE_HANDLE_EXPR_SET (expr
)->head
->expr
;
1297 gcc_assert (UNARY_CLASS_P (genop
)
1298 || BINARY_CLASS_P (genop
)
1299 || REFERENCE_CLASS_P (genop
));
1300 genop
= create_expression_by_pieces (block
, genop
, stmts
);
1306 /* Create an expression in pieces, so that we can handle very complex
1307 expressions that may be ANTIC, but not necessary GIMPLE.
1308 BLOCK is the basic block the expression will be inserted into,
1309 EXPR is the expression to insert (in value form)
1310 STMTS is a statement list to append the necessary insertions into.
1312 This function will abort if we hit some value that shouldn't be
1313 ANTIC but is (IE there is no leader for it, or its components).
1314 This function may also generate expressions that are themselves
1315 partially or fully redundant. Those that are will be either made
1316 fully redundant during the next iteration of insert (for partially
1317 redundant ones), or eliminated by eliminate (for fully redundant
1321 create_expression_by_pieces (basic_block block
, tree expr
, tree stmts
)
1323 tree name
= NULL_TREE
;
1324 tree newexpr
= NULL_TREE
;
1327 switch (TREE_CODE_CLASS (TREE_CODE (expr
)))
1331 tree_stmt_iterator tsi
;
1332 tree genop1
, genop2
;
1334 tree op1
= TREE_OPERAND (expr
, 0);
1335 tree op2
= TREE_OPERAND (expr
, 1);
1336 genop1
= find_or_generate_expression (block
, op1
, stmts
);
1337 genop2
= find_or_generate_expression (block
, op2
, stmts
);
1338 temp
= create_tmp_var (TREE_TYPE (expr
), "pretmp");
1339 add_referenced_tmp_var (temp
);
1340 newexpr
= build (TREE_CODE (expr
), TREE_TYPE (expr
),
1342 newexpr
= build (MODIFY_EXPR
, TREE_TYPE (expr
),
1344 name
= make_ssa_name (temp
, newexpr
);
1345 TREE_OPERAND (newexpr
, 0) = name
;
1346 tsi
= tsi_last (stmts
);
1347 tsi_link_after (&tsi
, newexpr
, TSI_CONTINUE_LINKING
);
1348 pre_stats
.insertions
++;
1353 tree_stmt_iterator tsi
;
1356 tree op1
= TREE_OPERAND (expr
, 0);
1357 genop1
= find_or_generate_expression (block
, op1
, stmts
);
1358 temp
= create_tmp_var (TREE_TYPE (expr
), "pretmp");
1359 add_referenced_tmp_var (temp
);
1360 newexpr
= build (TREE_CODE (expr
), TREE_TYPE (expr
),
1362 newexpr
= build (MODIFY_EXPR
, TREE_TYPE (expr
),
1364 name
= make_ssa_name (temp
, newexpr
);
1365 TREE_OPERAND (newexpr
, 0) = name
;
1366 tsi
= tsi_last (stmts
);
1367 tsi_link_after (&tsi
, newexpr
, TSI_CONTINUE_LINKING
);
1368 pre_stats
.insertions
++;
1376 v
= get_value_handle (expr
);
1377 vn_add (name
, v
, NULL
);
1378 bitmap_insert_into_set (NEW_SETS (block
), name
);
1379 bitmap_value_insert_into_set (AVAIL_OUT (block
), name
);
1380 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1382 fprintf (dump_file
, "Inserted ");
1383 print_generic_expr (dump_file
, newexpr
, 0);
1384 fprintf (dump_file
, " in predecessor %d\n", block
->index
);
1389 /* Perform insertion of partially redundant values.
1390 For BLOCK, do the following:
1391 1. Propagate the NEW_SETS of the dominator into the current block.
1392 If the block has multiple predecessors,
1393 2a. Iterate over the ANTIC expressions for the block to see if
1394 any of them are partially redundant.
1395 2b. If so, insert them into the necessary predecessors to make
1396 the expression fully redundant.
1397 2c. Insert a new PHI merging the values of the predecessors.
1398 2d. Insert the new PHI, and the new expressions, into the
1400 3. Recursively call ourselves on the dominator children of BLOCK.
1404 insert_aux (basic_block block
)
1407 bool new_stuff
= false;
1412 dom
= get_immediate_dominator (CDI_DOMINATORS
, block
);
1416 bitmap_set_t newset
= NEW_SETS (dom
);
1417 EXECUTE_IF_SET_IN_BITMAP (newset
->expressions
, 0, i
,
1419 bitmap_insert_into_set (NEW_SETS (block
), ssa_name (i
));
1420 bitmap_value_replace_in_set (AVAIL_OUT (block
), ssa_name (i
));
1422 if (block
->pred
->pred_next
)
1424 value_set_node_t node
;
1425 for (node
= ANTIC_IN (block
)->head
;
1429 if (BINARY_CLASS_P (node
->expr
)
1430 || UNARY_CLASS_P (node
->expr
))
1434 bool by_some
= false;
1435 bool cant_insert
= false;
1436 bool all_same
= true;
1437 tree first_s
= NULL
;
1442 val
= get_value_handle (node
->expr
);
1443 if (bitmap_set_contains_value (PHI_GEN (block
), val
))
1445 if (bitmap_set_contains_value (AVAIL_OUT (dom
), val
))
1447 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1448 fprintf (dump_file
, "Found fully redundant value\n");
1452 avail
= xcalloc (last_basic_block
, sizeof (tree
));
1453 for (pred
= block
->pred
;
1455 pred
= pred
->pred_next
)
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
[block
->pred
->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 (pred
= block
->pred
;
1528 pred
= pred
->pred_next
)
1530 tree stmts
= alloc_stmt_list ();
1533 eprime
= avail
[bprime
->index
];
1534 if (BINARY_CLASS_P (eprime
)
1535 || UNARY_CLASS_P (eprime
))
1537 builtexpr
= create_expression_by_pieces (bprime
,
1540 bsi_insert_on_edge (pred
, stmts
);
1541 bsi_commit_edge_inserts (NULL
);
1542 avail
[bprime
->index
] = builtexpr
;
1545 /* Now build a phi for the new variable. */
1546 temp
= create_tmp_var (type
, "prephitmp");
1547 add_referenced_tmp_var (temp
);
1548 temp
= create_phi_node (temp
, block
);
1549 vn_add (PHI_RESULT (temp
), val
, NULL
);
1552 if (!set_contains_value (AVAIL_OUT (block
), val
))
1553 insert_into_set (AVAIL_OUT (block
),
1557 bitmap_value_replace_in_set (AVAIL_OUT (block
),
1559 for (pred
= block
->pred
;
1561 pred
= pred
->pred_next
)
1563 add_phi_arg (&temp
, avail
[pred
->src
->index
],
1566 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1568 fprintf (dump_file
, "Created phi ");
1569 print_generic_expr (dump_file
, temp
, 0);
1570 fprintf (dump_file
, " in block %d\n", block
->index
);
1574 bitmap_insert_into_set (NEW_SETS (block
),
1576 bitmap_insert_into_set (PHI_GEN (block
),
1586 for (son
= first_dom_son (CDI_DOMINATORS
, block
);
1588 son
= next_dom_son (CDI_DOMINATORS
, son
))
1590 new_stuff
|= insert_aux (son
);
1596 /* Perform insertion of partially redundant values. */
1601 bool new_stuff
= true;
1603 int num_iterations
= 0;
1606 NEW_SETS (bb
) = bitmap_set_new ();
1612 new_stuff
= insert_aux (ENTRY_BLOCK_PTR
);
1614 if (num_iterations
> 2 && dump_file
&& (dump_flags
& TDF_STATS
))
1615 fprintf (dump_file
, "insert required %d iterations\n", num_iterations
);
1619 /* Return true if VAR is an SSA variable with no defining statement in
1620 this procedure, *AND* isn't a live-on-entry parameter. */
1623 is_undefined_value (tree expr
)
1625 return (TREE_CODE (expr
) == SSA_NAME
1626 && IS_EMPTY_STMT (SSA_NAME_DEF_STMT (expr
))
1627 /* PARM_DECLs and hard registers are always defined. */
1628 && TREE_CODE (SSA_NAME_VAR (expr
)) != PARM_DECL
1629 && !DECL_HARD_REGISTER (SSA_NAME_VAR (expr
)));
1633 /* Given an SSA variable VAR and an expression EXPR, compute the value
1634 number for EXPR and create a value handle (VAL) for it. If VAR and
1635 EXPR are not the same, associate VAL with VAR. Finally, add VAR to
1636 S1 and its value handle to S2.
1638 VUSES represent the virtual use operands associated with EXPR (if
1639 any). They are used when computing the hash value for EXPR. */
1642 add_to_sets (tree var
, tree expr
, vuse_optype vuses
, bitmap_set_t s1
,
1645 tree val
= vn_lookup_or_add (expr
, vuses
);
1647 /* VAR and EXPR may be the same when processing statements for which
1648 we are not computing value numbers (e.g., non-assignments, or
1649 statements that make aliased stores). In those cases, we are
1650 only interested in making VAR available as its own value. */
1652 vn_add (var
, val
, NULL
);
1654 bitmap_insert_into_set (s1
, var
);
1655 bitmap_value_insert_into_set (s2
, var
);
1659 /* Given a unary or binary expression EXPR, create and return a new
1660 expression with the same structure as EXPR but with its operands
1661 replaced with the value handles of each of the operands of EXPR.
1662 Insert EXPR's operands into the EXP_GEN set for BLOCK.
1664 VUSES represent the virtual use operands associated with EXPR (if
1665 any). They are used when computing the hash value for EXPR. */
1668 create_value_expr_from (tree expr
, basic_block block
, vuse_optype vuses
)
1671 enum tree_code code
= TREE_CODE (expr
);
1674 gcc_assert (TREE_CODE_CLASS (code
) == tcc_unary
1675 || TREE_CODE_CLASS (code
) == tcc_binary
1676 || TREE_CODE_CLASS (code
) == tcc_reference
);
1678 if (TREE_CODE_CLASS (code
) == tcc_unary
)
1679 vexpr
= pool_alloc (unary_node_pool
);
1680 else if (TREE_CODE_CLASS (code
) == tcc_reference
)
1681 vexpr
= pool_alloc (reference_node_pool
);
1683 vexpr
= pool_alloc (binary_node_pool
);
1685 memcpy (vexpr
, expr
, tree_size (expr
));
1687 for (i
= 0; i
< TREE_CODE_LENGTH (code
); i
++)
1689 tree op
= TREE_OPERAND (expr
, i
);
1692 tree val
= vn_lookup_or_add (op
, vuses
);
1693 if (!is_undefined_value (op
))
1694 value_insert_into_set (EXP_GEN (block
), op
);
1695 if (TREE_CODE (val
) == VALUE_HANDLE
)
1696 TREE_TYPE (val
) = TREE_TYPE (TREE_OPERAND (vexpr
, i
));
1697 TREE_OPERAND (vexpr
, i
) = val
;
1705 /* Compute the AVAIL set for BLOCK.
1706 This function performs value numbering of the statements in BLOCK.
1707 The AVAIL sets are built from information we glean while doing this
1708 value numbering, since the AVAIL sets contain only one entry per
1711 AVAIL_IN[BLOCK] = AVAIL_OUT[dom(BLOCK)].
1712 AVAIL_OUT[BLOCK] = AVAIL_IN[BLOCK] U PHI_GEN[BLOCK] U TMP_GEN[BLOCK]. */
1715 compute_avail (basic_block block
)
1719 /* For arguments with default definitions, we pretend they are
1720 defined in the entry block. */
1721 if (block
== ENTRY_BLOCK_PTR
)
1724 for (param
= DECL_ARGUMENTS (current_function_decl
);
1726 param
= TREE_CHAIN (param
))
1728 if (default_def (param
) != NULL
)
1731 tree def
= default_def (param
);
1732 val
= vn_lookup_or_add (def
, NULL
);
1733 bitmap_insert_into_set (TMP_GEN (block
), def
);
1734 bitmap_value_insert_into_set (AVAIL_OUT (block
), def
);
1740 block_stmt_iterator bsi
;
1744 /* Initially, the set of available values in BLOCK is that of
1745 its immediate dominator. */
1746 dom
= get_immediate_dominator (CDI_DOMINATORS
, block
);
1748 bitmap_set_copy (AVAIL_OUT (block
), AVAIL_OUT (dom
));
1750 /* Generate values for PHI nodes. */
1751 for (phi
= phi_nodes (block
); phi
; phi
= PHI_CHAIN (phi
))
1752 /* We have no need for virtual phis, as they don't represent
1753 actual computations. */
1754 if (is_gimple_reg (PHI_RESULT (phi
)))
1755 add_to_sets (PHI_RESULT (phi
), PHI_RESULT (phi
), NULL
,
1756 PHI_GEN (block
), AVAIL_OUT (block
));
1758 /* Now compute value numbers and populate value sets with all
1759 the expressions computed in BLOCK. */
1760 for (bsi
= bsi_start (block
); !bsi_end_p (bsi
); bsi_next (&bsi
))
1765 stmt
= bsi_stmt (bsi
);
1766 ann
= stmt_ann (stmt
);
1767 get_stmt_operands (stmt
);
1769 /* We are only interested in assignments of the form
1770 X_i = EXPR, where EXPR represents an "interesting"
1771 computation, it has no volatile operands and X_i
1772 doesn't flow through an abnormal edge. */
1773 if (TREE_CODE (stmt
) == MODIFY_EXPR
1774 && !ann
->has_volatile_ops
1775 && TREE_CODE (TREE_OPERAND (stmt
, 0)) == SSA_NAME
1776 && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (TREE_OPERAND (stmt
, 0)))
1778 tree lhs
= TREE_OPERAND (stmt
, 0);
1779 tree rhs
= TREE_OPERAND (stmt
, 1);
1780 vuse_optype vuses
= STMT_VUSE_OPS (stmt
);
1782 STRIP_USELESS_TYPE_CONVERSION (rhs
);
1783 if (TREE_CODE (rhs
) == SSA_NAME
1784 || is_gimple_min_invariant (rhs
))
1786 /* Compute a value number for the RHS of the statement
1787 and add its value to the AVAIL_OUT set for the block.
1788 Add the LHS to TMP_GEN. */
1789 add_to_sets (lhs
, rhs
, vuses
, TMP_GEN (block
),
1792 if (TREE_CODE (rhs
) == SSA_NAME
1793 && !is_undefined_value (rhs
))
1794 value_insert_into_set (EXP_GEN (block
), rhs
);
1797 else if (UNARY_CLASS_P (rhs
) || BINARY_CLASS_P (rhs
)
1798 || TREE_CODE (rhs
) == INDIRECT_REF
)
1800 /* For binary, unary, and reference expressions,
1801 create a duplicate expression with the operands
1802 replaced with the value handles of the original
1804 tree newt
= create_value_expr_from (rhs
, block
, vuses
);
1805 add_to_sets (lhs
, newt
, vuses
, TMP_GEN (block
),
1807 value_insert_into_set (EXP_GEN (block
), newt
);
1812 /* For any other statement that we don't recognize, simply
1813 make the names generated by the statement available in
1814 AVAIL_OUT and TMP_GEN. */
1815 for (j
= 0; j
< NUM_DEFS (STMT_DEF_OPS (stmt
)); j
++)
1817 tree def
= DEF_OP (STMT_DEF_OPS (stmt
), j
);
1818 add_to_sets (def
, def
, NULL
, TMP_GEN (block
),
1822 for (j
= 0; j
< NUM_USES (STMT_USE_OPS (stmt
)); j
++)
1824 tree use
= USE_OP (STMT_USE_OPS (stmt
), j
);
1825 add_to_sets (use
, use
, NULL
, TMP_GEN (block
),
1831 /* Compute available sets for the dominator children of BLOCK. */
1832 for (son
= first_dom_son (CDI_DOMINATORS
, block
);
1834 son
= next_dom_son (CDI_DOMINATORS
, son
))
1835 compute_avail (son
);
1839 /* Eliminate fully redundant computations. */
1848 block_stmt_iterator i
;
1850 for (i
= bsi_start (b
); !bsi_end_p (i
); bsi_next (&i
))
1852 tree stmt
= bsi_stmt (i
);
1854 /* Lookup the RHS of the expression, see if we have an
1855 available computation for it. If so, replace the RHS with
1856 the available computation. */
1857 if (TREE_CODE (stmt
) == MODIFY_EXPR
1858 && TREE_CODE (TREE_OPERAND (stmt
, 0)) == SSA_NAME
1859 && TREE_CODE (TREE_OPERAND (stmt
,1)) != SSA_NAME
1860 && !is_gimple_min_invariant (TREE_OPERAND (stmt
, 1))
1861 && !stmt_ann (stmt
)->has_volatile_ops
)
1863 tree lhs
= TREE_OPERAND (stmt
, 0);
1864 tree
*rhs_p
= &TREE_OPERAND (stmt
, 1);
1867 sprime
= bitmap_find_leader (AVAIL_OUT (b
),
1868 vn_lookup (lhs
, NULL
));
1871 && (TREE_CODE (*rhs_p
) != SSA_NAME
1872 || may_propagate_copy (*rhs_p
, sprime
)))
1874 gcc_assert (sprime
!= *rhs_p
);
1876 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1878 fprintf (dump_file
, "Replaced ");
1879 print_generic_expr (dump_file
, *rhs_p
, 0);
1880 fprintf (dump_file
, " with ");
1881 print_generic_expr (dump_file
, sprime
, 0);
1882 fprintf (dump_file
, " in ");
1883 print_generic_stmt (dump_file
, stmt
, 0);
1885 pre_stats
.eliminations
++;
1886 propagate_tree_value (rhs_p
, sprime
);
1889 /* If we removed EH side effects from the statement, clean
1890 its EH information. */
1891 if (maybe_clean_eh_stmt (stmt
))
1893 bitmap_set_bit (need_eh_cleanup
,
1894 bb_for_stmt (stmt
)->index
);
1895 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
1896 fprintf (dump_file
, " Removed EH side effects.\n");
1905 /* Initialize data structures used by PRE. */
1912 connect_infinite_loops_to_exit ();
1914 memset (&pre_stats
, 0, sizeof (pre_stats
));
1916 /* If block 0 has more than one predecessor, it means that its PHI
1917 nodes will have arguments coming from block -1. This creates
1918 problems for several places in PRE that keep local arrays indexed
1919 by block number. To prevent this, we split the edge coming from
1920 ENTRY_BLOCK_PTR (FIXME, if ENTRY_BLOCK_PTR had an index number
1921 different than -1 we wouldn't have to hack this. tree-ssa-dce.c
1922 needs a similar change). */
1923 if (ENTRY_BLOCK_PTR
->succ
->dest
->pred
->pred_next
)
1924 if (!(ENTRY_BLOCK_PTR
->succ
->flags
& EDGE_ABNORMAL
))
1925 split_edge (ENTRY_BLOCK_PTR
->succ
);
1928 bb
->aux
= xcalloc (1, sizeof (struct bb_value_sets
));
1930 gcc_obstack_init (&grand_bitmap_obstack
);
1931 phi_translate_table
= htab_create (511, expr_pred_trans_hash
,
1932 expr_pred_trans_eq
, free
);
1933 value_set_pool
= create_alloc_pool ("Value sets",
1934 sizeof (struct value_set
), 30);
1935 bitmap_set_pool
= create_alloc_pool ("Bitmap sets",
1936 sizeof (struct bitmap_set
), 30);
1937 value_set_node_pool
= create_alloc_pool ("Value set nodes",
1938 sizeof (struct value_set_node
), 30);
1939 calculate_dominance_info (CDI_POST_DOMINATORS
);
1940 calculate_dominance_info (CDI_DOMINATORS
);
1941 binary_node_pool
= create_alloc_pool ("Binary tree nodes",
1942 tree_code_size (PLUS_EXPR
), 30);
1943 unary_node_pool
= create_alloc_pool ("Unary tree nodes",
1944 tree_code_size (NEGATE_EXPR
), 30);
1945 reference_node_pool
= create_alloc_pool ("Reference tree nodes",
1946 tree_code_size (COMPONENT_REF
), 30);
1949 EXP_GEN (bb
) = set_new (true);
1950 PHI_GEN (bb
) = bitmap_set_new ();
1951 TMP_GEN (bb
) = bitmap_set_new ();
1952 AVAIL_OUT (bb
) = bitmap_set_new ();
1955 need_eh_cleanup
= BITMAP_XMALLOC ();
1959 /* Deallocate data structures used by PRE. */
1966 obstack_free (&grand_bitmap_obstack
, NULL
);
1967 free_alloc_pool (value_set_pool
);
1968 free_alloc_pool (bitmap_set_pool
);
1969 free_alloc_pool (value_set_node_pool
);
1970 free_alloc_pool (binary_node_pool
);
1971 free_alloc_pool (reference_node_pool
);
1972 free_alloc_pool (unary_node_pool
);
1973 htab_delete (phi_translate_table
);
1974 remove_fake_exit_edges ();
1982 free_dominance_info (CDI_POST_DOMINATORS
);
1985 if (bitmap_first_set_bit (need_eh_cleanup
) >= 0)
1987 tree_purge_all_dead_eh_edges (need_eh_cleanup
);
1988 cleanup_tree_cfg ();
1991 BITMAP_XFREE (need_eh_cleanup
);
1995 /* Main entry point to the SSA-PRE pass. DO_FRE is true if the caller
1996 only wants to do full redundancy elimination. */
1999 execute_pre (bool do_fre
)
2003 /* Collect and value number expressions computed in each basic
2005 compute_avail (ENTRY_BLOCK_PTR
);
2007 if (dump_file
&& (dump_flags
& TDF_DETAILS
))
2013 print_value_set (dump_file
, EXP_GEN (bb
), "exp_gen", bb
->index
);
2014 bitmap_print_value_set (dump_file
, TMP_GEN (bb
), "tmp_gen",
2016 bitmap_print_value_set (dump_file
, AVAIL_OUT (bb
), "avail_out",
2021 /* Insert can get quite slow on an incredibly large number of basic
2022 blocks due to some quadratic behavior. Until this behavior is
2023 fixed, don't run it when he have an incredibly large number of
2024 bb's. If we aren't going to run insert, there is no point in
2025 computing ANTIC, either, even though it's plenty fast. */
2026 if (!do_fre
&& n_basic_blocks
< 4000)
2032 /* Remove all the redundant expressions. */
2035 if (dump_file
&& (dump_flags
& TDF_STATS
))
2037 fprintf (dump_file
, "Insertions:%d\n", pre_stats
.insertions
);
2038 fprintf (dump_file
, "New PHIs:%d\n", pre_stats
.phis
);
2039 fprintf (dump_file
, "Eliminated:%d\n", pre_stats
.eliminations
);
2046 /* Gate and execute functions for PRE. */
2051 execute_pre (false);
2057 return flag_tree_pre
!= 0;
2060 struct tree_opt_pass pass_pre
=
2063 gate_pre
, /* gate */
2064 do_pre
, /* execute */
2067 0, /* static_pass_number */
2068 TV_TREE_PRE
, /* tv_id */
2069 PROP_no_crit_edges
| PROP_cfg
2070 | PROP_ssa
| PROP_alias
, /* properties_required */
2071 0, /* properties_provided */
2072 0, /* properties_destroyed */
2073 0, /* todo_flags_start */
2074 TODO_dump_func
| TODO_ggc_collect
| TODO_verify_ssa
, /* todo_flags_finish */
2079 /* Gate and execute functions for FRE. */
2090 return flag_tree_fre
!= 0;
2093 struct tree_opt_pass pass_fre
=
2096 gate_fre
, /* gate */
2097 do_fre
, /* execute */
2100 0, /* static_pass_number */
2101 TV_TREE_FRE
, /* tv_id */
2102 PROP_cfg
| PROP_ssa
| PROP_alias
, /* properties_required */
2103 0, /* properties_provided */
2104 0, /* properties_destroyed */
2105 0, /* todo_flags_start */
2106 TODO_dump_func
| TODO_ggc_collect
| TODO_verify_ssa
, /* todo_flags_finish */