1 /* RTL dead store elimination.
2 Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011
3 Free Software Foundation, Inc.
5 Contributed by Richard Sandiford <rsandifor@codesourcery.com>
6 and Kenneth Zadeck <zadeck@naturalbridge.com>
8 This file is part of GCC.
10 GCC is free software; you can redistribute it and/or modify it under
11 the terms of the GNU General Public License as published by the Free
12 Software Foundation; either version 3, or (at your option) any later
15 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
16 WARRANTY; without even the implied warranty of MERCHANTABILITY or
17 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
20 You should have received a copy of the GNU General Public License
21 along with GCC; see the file COPYING3. If not see
22 <http://www.gnu.org/licenses/>. */
28 #include "coretypes.h"
35 #include "hard-reg-set.h"
40 #include "tree-pass.h"
41 #include "alloc-pool.h"
43 #include "insn-config.h"
51 #include "tree-flow.h"
53 /* This file contains three techniques for performing Dead Store
56 * The first technique performs dse locally on any base address. It
57 is based on the cselib which is a local value numbering technique.
58 This technique is local to a basic block but deals with a fairly
61 * The second technique performs dse globally but is restricted to
62 base addresses that are either constant or are relative to the
65 * The third technique, (which is only done after register allocation)
66 processes the spill spill slots. This differs from the second
67 technique because it takes advantage of the fact that spilling is
68 completely free from the effects of aliasing.
70 Logically, dse is a backwards dataflow problem. A store can be
71 deleted if it if cannot be reached in the backward direction by any
72 use of the value being stored. However, the local technique uses a
73 forwards scan of the basic block because cselib requires that the
74 block be processed in that order.
76 The pass is logically broken into 7 steps:
80 1) The local algorithm, as well as scanning the insns for the two
83 2) Analysis to see if the global algs are necessary. In the case
84 of stores base on a constant address, there must be at least two
85 stores to that address, to make it possible to delete some of the
86 stores. In the case of stores off of the frame or spill related
87 stores, only one store to an address is necessary because those
88 stores die at the end of the function.
90 3) Set up the global dataflow equations based on processing the
91 info parsed in the first step.
93 4) Solve the dataflow equations.
95 5) Delete the insns that the global analysis has indicated are
98 6) Delete insns that store the same value as preceeding store
99 where the earlier store couldn't be eliminated.
103 This step uses cselib and canon_rtx to build the largest expression
104 possible for each address. This pass is a forwards pass through
105 each basic block. From the point of view of the global technique,
106 the first pass could examine a block in either direction. The
107 forwards ordering is to accommodate cselib.
109 We a simplifying assumption: addresses fall into four broad
112 1) base has rtx_varies_p == false, offset is constant.
113 2) base has rtx_varies_p == false, offset variable.
114 3) base has rtx_varies_p == true, offset constant.
115 4) base has rtx_varies_p == true, offset variable.
117 The local passes are able to process all 4 kinds of addresses. The
118 global pass only handles (1).
120 The global problem is formulated as follows:
122 A store, S1, to address A, where A is not relative to the stack
123 frame, can be eliminated if all paths from S1 to the end of the
124 of the function contain another store to A before a read to A.
126 If the address A is relative to the stack frame, a store S2 to A
127 can be eliminated if there are no paths from S1 that reach the
128 end of the function that read A before another store to A. In
129 this case S2 can be deleted if there are paths to from S2 to the
130 end of the function that have no reads or writes to A. This
131 second case allows stores to the stack frame to be deleted that
132 would otherwise die when the function returns. This cannot be
133 done if stores_off_frame_dead_at_return is not true. See the doc
134 for that variable for when this variable is false.
136 The global problem is formulated as a backwards set union
137 dataflow problem where the stores are the gens and reads are the
138 kills. Set union problems are rare and require some special
139 handling given our representation of bitmaps. A straightforward
140 implementation of requires a lot of bitmaps filled with 1s.
141 These are expensive and cumbersome in our bitmap formulation so
142 care has been taken to avoid large vectors filled with 1s. See
143 the comments in bb_info and in the dataflow confluence functions
146 There are two places for further enhancements to this algorithm:
148 1) The original dse which was embedded in a pass called flow also
149 did local address forwarding. For example in
154 flow would replace the right hand side of the second insn with a
155 reference to r100. Most of the information is available to add this
156 to this pass. It has not done it because it is a lot of work in
157 the case that either r100 is assigned to between the first and
158 second insn and/or the second insn is a load of part of the value
159 stored by the first insn.
161 insn 5 in gcc.c-torture/compile/990203-1.c simple case.
162 insn 15 in gcc.c-torture/execute/20001017-2.c simple case.
163 insn 25 in gcc.c-torture/execute/20001026-1.c simple case.
164 insn 44 in gcc.c-torture/execute/20010910-1.c simple case.
166 2) The cleaning up of spill code is quite profitable. It currently
167 depends on reading tea leaves and chicken entrails left by reload.
168 This pass depends on reload creating a singleton alias set for each
169 spill slot and telling the next dse pass which of these alias sets
170 are the singletons. Rather than analyze the addresses of the
171 spills, dse's spill processing just does analysis of the loads and
172 stores that use those alias sets. There are three cases where this
175 a) Reload sometimes creates the slot for one mode of access, and
176 then inserts loads and/or stores for a smaller mode. In this
177 case, the current code just punts on the slot. The proper thing
178 to do is to back out and use one bit vector position for each
179 byte of the entity associated with the slot. This depends on
180 KNOWING that reload always generates the accesses for each of the
181 bytes in some canonical (read that easy to understand several
182 passes after reload happens) way.
184 b) Reload sometimes decides that spill slot it allocated was not
185 large enough for the mode and goes back and allocates more slots
186 with the same mode and alias set. The backout in this case is a
187 little more graceful than (a). In this case the slot is unmarked
188 as being a spill slot and if final address comes out to be based
189 off the frame pointer, the global algorithm handles this slot.
191 c) For any pass that may prespill, there is currently no
192 mechanism to tell the dse pass that the slot being used has the
193 special properties that reload uses. It may be that all that is
194 required is to have those passes make the same calls that reload
195 does, assuming that the alias sets can be manipulated in the same
198 /* There are limits to the size of constant offsets we model for the
199 global problem. There are certainly test cases, that exceed this
200 limit, however, it is unlikely that there are important programs
201 that really have constant offsets this size. */
202 #define MAX_OFFSET (64 * 1024)
205 static bitmap scratch = NULL;
208 /* This structure holds information about a candidate store. */
212 /* False means this is a clobber. */
215 /* False if a single HOST_WIDE_INT bitmap is used for positions_needed. */
218 /* The id of the mem group of the base address. If rtx_varies_p is
219 true, this is -1. Otherwise, it is the index into the group
223 /* This is the cselib value. */
224 cselib_val *cse_base;
226 /* This canonized mem. */
229 /* Canonized MEM address for use by canon_true_dependence. */
232 /* If this is non-zero, it is the alias set of a spill location. */
233 alias_set_type alias_set;
235 /* The offset of the first and byte before the last byte associated
236 with the operation. */
237 HOST_WIDE_INT begin, end;
241 /* A bitmask as wide as the number of bytes in the word that
242 contains a 1 if the byte may be needed. The store is unused if
243 all of the bits are 0. This is used if IS_LARGE is false. */
244 unsigned HOST_WIDE_INT small_bitmask;
248 /* A bitmap with one bit per byte. Cleared bit means the position
249 is needed. Used if IS_LARGE is false. */
252 /* Number of set bits (i.e. unneeded bytes) in BITMAP. If it is
253 equal to END - BEGIN, the whole store is unused. */
258 /* The next store info for this insn. */
259 struct store_info *next;
261 /* The right hand side of the store. This is used if there is a
262 subsequent reload of the mems address somewhere later in the
266 /* If rhs is or holds a constant, this contains that constant,
270 /* Set if this store stores the same constant value as REDUNDANT_REASON
271 insn stored. These aren't eliminated early, because doing that
272 might prevent the earlier larger store to be eliminated. */
273 struct insn_info *redundant_reason;
276 /* Return a bitmask with the first N low bits set. */
278 static unsigned HOST_WIDE_INT
279 lowpart_bitmask (int n)
281 unsigned HOST_WIDE_INT mask = ~(unsigned HOST_WIDE_INT) 0;
282 return mask >> (HOST_BITS_PER_WIDE_INT - n);
285 typedef struct store_info *store_info_t;
286 static alloc_pool cse_store_info_pool;
287 static alloc_pool rtx_store_info_pool;
289 /* This structure holds information about a load. These are only
290 built for rtx bases. */
293 /* The id of the mem group of the base address. */
296 /* If this is non-zero, it is the alias set of a spill location. */
297 alias_set_type alias_set;
299 /* The offset of the first and byte after the last byte associated
300 with the operation. If begin == end == 0, the read did not have
301 a constant offset. */
304 /* The mem being read. */
307 /* The next read_info for this insn. */
308 struct read_info *next;
310 typedef struct read_info *read_info_t;
311 static alloc_pool read_info_pool;
314 /* One of these records is created for each insn. */
318 /* Set true if the insn contains a store but the insn itself cannot
319 be deleted. This is set if the insn is a parallel and there is
320 more than one non dead output or if the insn is in some way
324 /* This field is only used by the global algorithm. It is set true
325 if the insn contains any read of mem except for a (1). This is
326 also set if the insn is a call or has a clobber mem. If the insn
327 contains a wild read, the use_rec will be null. */
330 /* This is true only for CALL instructions which could potentially read
331 any non-frame memory location. This field is used by the global
333 bool non_frame_wild_read;
335 /* This field is only used for the processing of const functions.
336 These functions cannot read memory, but they can read the stack
337 because that is where they may get their parms. We need to be
338 this conservative because, like the store motion pass, we don't
339 consider CALL_INSN_FUNCTION_USAGE when processing call insns.
340 Moreover, we need to distinguish two cases:
341 1. Before reload (register elimination), the stores related to
342 outgoing arguments are stack pointer based and thus deemed
343 of non-constant base in this pass. This requires special
344 handling but also means that the frame pointer based stores
345 need not be killed upon encountering a const function call.
346 2. After reload, the stores related to outgoing arguments can be
347 either stack pointer or hard frame pointer based. This means
348 that we have no other choice than also killing all the frame
349 pointer based stores upon encountering a const function call.
350 This field is set after reload for const function calls. Having
351 this set is less severe than a wild read, it just means that all
352 the frame related stores are killed rather than all the stores. */
355 /* This field is only used for the processing of const functions.
356 It is set if the insn may contain a stack pointer based store. */
357 bool stack_pointer_based;
359 /* This is true if any of the sets within the store contains a
360 cselib base. Such stores can only be deleted by the local
362 bool contains_cselib_groups;
367 /* The list of mem sets or mem clobbers that are contained in this
368 insn. If the insn is deletable, it contains only one mem set.
369 But it could also contain clobbers. Insns that contain more than
370 one mem set are not deletable, but each of those mems are here in
371 order to provide info to delete other insns. */
372 store_info_t store_rec;
374 /* The linked list of mem uses in this insn. Only the reads from
375 rtx bases are listed here. The reads to cselib bases are
376 completely processed during the first scan and so are never
378 read_info_t read_rec;
380 /* The prev insn in the basic block. */
381 struct insn_info * prev_insn;
383 /* The linked list of insns that are in consideration for removal in
384 the forwards pass thru the basic block. This pointer may be
385 trash as it is not cleared when a wild read occurs. The only
386 time it is guaranteed to be correct is when the traversal starts
387 at active_local_stores. */
388 struct insn_info * next_local_store;
391 typedef struct insn_info *insn_info_t;
392 static alloc_pool insn_info_pool;
394 /* The linked list of stores that are under consideration in this
396 static insn_info_t active_local_stores;
397 static int active_local_stores_len;
402 /* Pointer to the insn info for the last insn in the block. These
403 are linked so this is how all of the insns are reached. During
404 scanning this is the current insn being scanned. */
405 insn_info_t last_insn;
407 /* The info for the global dataflow problem. */
410 /* This is set if the transfer function should and in the wild_read
411 bitmap before applying the kill and gen sets. That vector knocks
412 out most of the bits in the bitmap and thus speeds up the
414 bool apply_wild_read;
416 /* The following 4 bitvectors hold information about which positions
417 of which stores are live or dead. They are indexed by
420 /* The set of store positions that exist in this block before a wild read. */
423 /* The set of load positions that exist in this block above the
424 same position of a store. */
427 /* The set of stores that reach the top of the block without being
430 Do not represent the in if it is all ones. Note that this is
431 what the bitvector should logically be initialized to for a set
432 intersection problem. However, like the kill set, this is too
433 expensive. So initially, the in set will only be created for the
434 exit block and any block that contains a wild read. */
437 /* The set of stores that reach the bottom of the block from it's
440 Do not represent the in if it is all ones. Note that this is
441 what the bitvector should logically be initialized to for a set
442 intersection problem. However, like the kill and in set, this is
443 too expensive. So what is done is that the confluence operator
444 just initializes the vector from one of the out sets of the
445 successors of the block. */
448 /* The following bitvector is indexed by the reg number. It
449 contains the set of regs that are live at the current instruction
450 being processed. While it contains info for all of the
451 registers, only the pseudos are actually examined. It is used to
452 assure that shift sequences that are inserted do not accidently
453 clobber live hard regs. */
457 typedef struct bb_info *bb_info_t;
458 static alloc_pool bb_info_pool;
460 /* Table to hold all bb_infos. */
461 static bb_info_t *bb_table;
463 /* There is a group_info for each rtx base that is used to reference
464 memory. There are also not many of the rtx bases because they are
465 very limited in scope. */
469 /* The actual base of the address. */
472 /* The sequential id of the base. This allows us to have a
473 canonical ordering of these that is not based on addresses. */
476 /* True if there are any positions that are to be processed
478 bool process_globally;
480 /* True if the base of this group is either the frame_pointer or
481 hard_frame_pointer. */
484 /* A mem wrapped around the base pointer for the group in order to do
485 read dependency. It must be given BLKmode in order to encompass all
486 the possible offsets from the base. */
489 /* Canonized version of base_mem's address. */
492 /* These two sets of two bitmaps are used to keep track of how many
493 stores are actually referencing that position from this base. We
494 only do this for rtx bases as this will be used to assign
495 positions in the bitmaps for the global problem. Bit N is set in
496 store1 on the first store for offset N. Bit N is set in store2
497 for the second store to offset N. This is all we need since we
498 only care about offsets that have two or more stores for them.
500 The "_n" suffix is for offsets less than 0 and the "_p" suffix is
501 for 0 and greater offsets.
503 There is one special case here, for stores into the stack frame,
504 we will or store1 into store2 before deciding which stores look
505 at globally. This is because stores to the stack frame that have
506 no other reads before the end of the function can also be
508 bitmap store1_n, store1_p, store2_n, store2_p;
510 /* These bitmaps keep track of offsets in this group escape this function.
511 An offset escapes if it corresponds to a named variable whose
512 addressable flag is set. */
513 bitmap escaped_n, escaped_p;
515 /* The positions in this bitmap have the same assignments as the in,
516 out, gen and kill bitmaps. This bitmap is all zeros except for
517 the positions that are occupied by stores for this group. */
520 /* The offset_map is used to map the offsets from this base into
521 positions in the global bitmaps. It is only created after all of
522 the all of stores have been scanned and we know which ones we
524 int *offset_map_n, *offset_map_p;
525 int offset_map_size_n, offset_map_size_p;
527 typedef struct group_info *group_info_t;
528 typedef const struct group_info *const_group_info_t;
529 static alloc_pool rtx_group_info_pool;
531 /* Tables of group_info structures, hashed by base value. */
532 static htab_t rtx_group_table;
534 /* Index into the rtx_group_vec. */
535 static int rtx_group_next_id;
537 DEF_VEC_P(group_info_t);
538 DEF_VEC_ALLOC_P(group_info_t,heap);
540 static VEC(group_info_t,heap) *rtx_group_vec;
543 /* This structure holds the set of changes that are being deferred
544 when removing read operation. See replace_read. */
545 struct deferred_change
548 /* The mem that is being replaced. */
551 /* The reg it is being replaced with. */
554 struct deferred_change *next;
557 typedef struct deferred_change *deferred_change_t;
558 static alloc_pool deferred_change_pool;
560 static deferred_change_t deferred_change_list = NULL;
562 /* This are used to hold the alias sets of spill variables. Since
563 these are never aliased and there may be a lot of them, it makes
564 sense to treat them specially. This bitvector is only allocated in
565 calls from dse_record_singleton_alias_set which currently is only
566 made during reload1. So when dse is called before reload this
567 mechanism does nothing. */
569 static bitmap clear_alias_sets = NULL;
571 /* The set of clear_alias_sets that have been disqualified because
572 there are loads or stores using a different mode than the alias set
573 was registered with. */
574 static bitmap disqualified_clear_alias_sets = NULL;
576 /* The group that holds all of the clear_alias_sets. */
577 static group_info_t clear_alias_group;
579 /* The modes of the clear_alias_sets. */
580 static htab_t clear_alias_mode_table;
582 /* Hash table element to look up the mode for an alias set. */
583 struct clear_alias_mode_holder
585 alias_set_type alias_set;
586 enum machine_mode mode;
589 static alloc_pool clear_alias_mode_pool;
591 /* This is true except if cfun->stdarg -- i.e. we cannot do
592 this for vararg functions because they play games with the frame. */
593 static bool stores_off_frame_dead_at_return;
595 /* Counter for stats. */
596 static int globally_deleted;
597 static int locally_deleted;
598 static int spill_deleted;
600 static bitmap all_blocks;
602 /* Locations that are killed by calls in the global phase. */
603 static bitmap kill_on_calls;
605 /* The number of bits used in the global bitmaps. */
606 static unsigned int current_position;
609 static bool gate_dse (void);
610 static bool gate_dse1 (void);
611 static bool gate_dse2 (void);
614 /*----------------------------------------------------------------------------
618 ----------------------------------------------------------------------------*/
620 /* Hashtable callbacks for maintaining the "bases" field of
621 store_group_info, given that the addresses are function invariants. */
624 clear_alias_mode_eq (const void *p1, const void *p2)
626 const struct clear_alias_mode_holder * h1
627 = (const struct clear_alias_mode_holder *) p1;
628 const struct clear_alias_mode_holder * h2
629 = (const struct clear_alias_mode_holder *) p2;
630 return h1->alias_set == h2->alias_set;
635 clear_alias_mode_hash (const void *p)
637 const struct clear_alias_mode_holder *holder
638 = (const struct clear_alias_mode_holder *) p;
639 return holder->alias_set;
643 /* Find the entry associated with ALIAS_SET. */
645 static struct clear_alias_mode_holder *
646 clear_alias_set_lookup (alias_set_type alias_set)
648 struct clear_alias_mode_holder tmp_holder;
651 tmp_holder.alias_set = alias_set;
652 slot = htab_find_slot (clear_alias_mode_table, &tmp_holder, NO_INSERT);
655 return (struct clear_alias_mode_holder *) *slot;
659 /* Hashtable callbacks for maintaining the "bases" field of
660 store_group_info, given that the addresses are function invariants. */
663 invariant_group_base_eq (const void *p1, const void *p2)
665 const_group_info_t gi1 = (const_group_info_t) p1;
666 const_group_info_t gi2 = (const_group_info_t) p2;
667 return rtx_equal_p (gi1->rtx_base, gi2->rtx_base);
672 invariant_group_base_hash (const void *p)
674 const_group_info_t gi = (const_group_info_t) p;
676 return hash_rtx (gi->rtx_base, Pmode, &do_not_record, NULL, false);
680 /* Get the GROUP for BASE. Add a new group if it is not there. */
683 get_group_info (rtx base)
685 struct group_info tmp_gi;
691 /* Find the store_base_info structure for BASE, creating a new one
693 tmp_gi.rtx_base = base;
694 slot = htab_find_slot (rtx_group_table, &tmp_gi, INSERT);
695 gi = (group_info_t) *slot;
699 if (!clear_alias_group)
701 clear_alias_group = gi =
702 (group_info_t) pool_alloc (rtx_group_info_pool);
703 memset (gi, 0, sizeof (struct group_info));
704 gi->id = rtx_group_next_id++;
705 gi->store1_n = BITMAP_ALLOC (NULL);
706 gi->store1_p = BITMAP_ALLOC (NULL);
707 gi->store2_n = BITMAP_ALLOC (NULL);
708 gi->store2_p = BITMAP_ALLOC (NULL);
709 gi->escaped_p = BITMAP_ALLOC (NULL);
710 gi->escaped_n = BITMAP_ALLOC (NULL);
711 gi->group_kill = BITMAP_ALLOC (NULL);
712 gi->process_globally = false;
713 gi->offset_map_size_n = 0;
714 gi->offset_map_size_p = 0;
715 gi->offset_map_n = NULL;
716 gi->offset_map_p = NULL;
717 VEC_safe_push (group_info_t, heap, rtx_group_vec, gi);
719 return clear_alias_group;
724 *slot = gi = (group_info_t) pool_alloc (rtx_group_info_pool);
726 gi->id = rtx_group_next_id++;
727 gi->base_mem = gen_rtx_MEM (BLKmode, base);
728 gi->canon_base_addr = canon_rtx (base);
729 gi->store1_n = BITMAP_ALLOC (NULL);
730 gi->store1_p = BITMAP_ALLOC (NULL);
731 gi->store2_n = BITMAP_ALLOC (NULL);
732 gi->store2_p = BITMAP_ALLOC (NULL);
733 gi->escaped_p = BITMAP_ALLOC (NULL);
734 gi->escaped_n = BITMAP_ALLOC (NULL);
735 gi->group_kill = BITMAP_ALLOC (NULL);
736 gi->process_globally = false;
738 (base == frame_pointer_rtx) || (base == hard_frame_pointer_rtx);
739 gi->offset_map_size_n = 0;
740 gi->offset_map_size_p = 0;
741 gi->offset_map_n = NULL;
742 gi->offset_map_p = NULL;
743 VEC_safe_push (group_info_t, heap, rtx_group_vec, gi);
750 /* Initialization of data structures. */
756 globally_deleted = 0;
759 scratch = BITMAP_ALLOC (NULL);
760 kill_on_calls = BITMAP_ALLOC (NULL);
763 = create_alloc_pool ("rtx_store_info_pool",
764 sizeof (struct store_info), 100);
766 = create_alloc_pool ("read_info_pool",
767 sizeof (struct read_info), 100);
769 = create_alloc_pool ("insn_info_pool",
770 sizeof (struct insn_info), 100);
772 = create_alloc_pool ("bb_info_pool",
773 sizeof (struct bb_info), 100);
775 = create_alloc_pool ("rtx_group_info_pool",
776 sizeof (struct group_info), 100);
778 = create_alloc_pool ("deferred_change_pool",
779 sizeof (struct deferred_change), 10);
781 rtx_group_table = htab_create (11, invariant_group_base_hash,
782 invariant_group_base_eq, NULL);
784 bb_table = XCNEWVEC (bb_info_t, last_basic_block);
785 rtx_group_next_id = 0;
787 stores_off_frame_dead_at_return = !cfun->stdarg;
789 init_alias_analysis ();
791 if (clear_alias_sets)
792 clear_alias_group = get_group_info (NULL);
794 clear_alias_group = NULL;
799 /*----------------------------------------------------------------------------
802 Scan all of the insns. Any random ordering of the blocks is fine.
803 Each block is scanned in forward order to accommodate cselib which
804 is used to remove stores with non-constant bases.
805 ----------------------------------------------------------------------------*/
807 /* Delete all of the store_info recs from INSN_INFO. */
810 free_store_info (insn_info_t insn_info)
812 store_info_t store_info = insn_info->store_rec;
815 store_info_t next = store_info->next;
816 if (store_info->is_large)
817 BITMAP_FREE (store_info->positions_needed.large.bmap);
818 if (store_info->cse_base)
819 pool_free (cse_store_info_pool, store_info);
821 pool_free (rtx_store_info_pool, store_info);
825 insn_info->cannot_delete = true;
826 insn_info->contains_cselib_groups = false;
827 insn_info->store_rec = NULL;
830 /* Callback for for_each_inc_dec that emits an INSN that sets DEST to
831 SRC + SRCOFF before insn ARG. */
834 emit_inc_dec_insn_before (rtx mem ATTRIBUTE_UNUSED,
835 rtx op ATTRIBUTE_UNUSED,
836 rtx dest, rtx src, rtx srcoff, void *arg)
841 src = gen_rtx_PLUS (GET_MODE (src), src, srcoff);
843 /* We can reuse all operands without copying, because we are about
844 to delete the insn that contained it. */
846 emit_insn_before (gen_rtx_SET (VOIDmode, dest, src), insn);
851 /* Before we delete INSN, make sure that the auto inc/dec, if it is
852 there, is split into a separate insn. */
855 check_for_inc_dec (rtx insn)
857 rtx note = find_reg_note (insn, REG_INC, NULL_RTX);
859 for_each_inc_dec (&insn, emit_inc_dec_insn_before, insn);
863 /* Delete the insn and free all of the fields inside INSN_INFO. */
866 delete_dead_store_insn (insn_info_t insn_info)
868 read_info_t read_info;
873 check_for_inc_dec (insn_info->insn);
876 fprintf (dump_file, "Locally deleting insn %d ",
877 INSN_UID (insn_info->insn));
878 if (insn_info->store_rec->alias_set)
879 fprintf (dump_file, "alias set %d\n",
880 (int) insn_info->store_rec->alias_set);
882 fprintf (dump_file, "\n");
885 free_store_info (insn_info);
886 read_info = insn_info->read_rec;
890 read_info_t next = read_info->next;
891 pool_free (read_info_pool, read_info);
894 insn_info->read_rec = NULL;
896 delete_insn (insn_info->insn);
898 insn_info->insn = NULL;
900 insn_info->wild_read = false;
903 /* Check if EXPR can possibly escape the current function scope. */
905 can_escape (tree expr)
910 base = get_base_address (expr);
912 && !may_be_aliased (base))
917 /* Set the store* bitmaps offset_map_size* fields in GROUP based on
921 set_usage_bits (group_info_t group, HOST_WIDE_INT offset, HOST_WIDE_INT width,
925 bool expr_escapes = can_escape (expr);
926 if (offset > -MAX_OFFSET && offset + width < MAX_OFFSET)
927 for (i=offset; i<offset+width; i++)
935 store1 = group->store1_n;
936 store2 = group->store2_n;
937 escaped = group->escaped_n;
942 store1 = group->store1_p;
943 store2 = group->store2_p;
944 escaped = group->escaped_p;
948 if (!bitmap_set_bit (store1, ai))
949 bitmap_set_bit (store2, ai);
954 if (group->offset_map_size_n < ai)
955 group->offset_map_size_n = ai;
959 if (group->offset_map_size_p < ai)
960 group->offset_map_size_p = ai;
964 bitmap_set_bit (escaped, ai);
969 reset_active_stores (void)
971 active_local_stores = NULL;
972 active_local_stores_len = 0;
975 /* Free all READ_REC of the LAST_INSN of BB_INFO. */
978 free_read_records (bb_info_t bb_info)
980 insn_info_t insn_info = bb_info->last_insn;
981 read_info_t *ptr = &insn_info->read_rec;
984 read_info_t next = (*ptr)->next;
985 if ((*ptr)->alias_set == 0)
987 pool_free (read_info_pool, *ptr);
995 /* Set the BB_INFO so that the last insn is marked as a wild read. */
998 add_wild_read (bb_info_t bb_info)
1000 insn_info_t insn_info = bb_info->last_insn;
1001 insn_info->wild_read = true;
1002 free_read_records (bb_info);
1003 reset_active_stores ();
1006 /* Set the BB_INFO so that the last insn is marked as a wild read of
1007 non-frame locations. */
1010 add_non_frame_wild_read (bb_info_t bb_info)
1012 insn_info_t insn_info = bb_info->last_insn;
1013 insn_info->non_frame_wild_read = true;
1014 free_read_records (bb_info);
1015 reset_active_stores ();
1018 /* Return true if X is a constant or one of the registers that behave
1019 as a constant over the life of a function. This is equivalent to
1020 !rtx_varies_p for memory addresses. */
1023 const_or_frame_p (rtx x)
1025 switch (GET_CODE (x))
1036 /* Note that we have to test for the actual rtx used for the frame
1037 and arg pointers and not just the register number in case we have
1038 eliminated the frame and/or arg pointer and are using it
1040 if (x == frame_pointer_rtx || x == hard_frame_pointer_rtx
1041 /* The arg pointer varies if it is not a fixed register. */
1042 || (x == arg_pointer_rtx && fixed_regs[ARG_POINTER_REGNUM])
1043 || x == pic_offset_table_rtx)
1052 /* Take all reasonable action to put the address of MEM into the form
1053 that we can do analysis on.
1055 The gold standard is to get the address into the form: address +
1056 OFFSET where address is something that rtx_varies_p considers a
1057 constant. When we can get the address in this form, we can do
1058 global analysis on it. Note that for constant bases, address is
1059 not actually returned, only the group_id. The address can be
1062 If that fails, we try cselib to get a value we can at least use
1063 locally. If that fails we return false.
1065 The GROUP_ID is set to -1 for cselib bases and the index of the
1066 group for non_varying bases.
1068 FOR_READ is true if this is a mem read and false if not. */
1071 canon_address (rtx mem,
1072 alias_set_type *alias_set_out,
1074 HOST_WIDE_INT *offset,
1077 enum machine_mode address_mode
1078 = targetm.addr_space.address_mode (MEM_ADDR_SPACE (mem));
1079 rtx mem_address = XEXP (mem, 0);
1080 rtx expanded_address, address;
1083 /* Make sure that cselib is has initialized all of the operands of
1084 the address before asking it to do the subst. */
1086 if (clear_alias_sets)
1088 /* If this is a spill, do not do any further processing. */
1089 alias_set_type alias_set = MEM_ALIAS_SET (mem);
1091 fprintf (dump_file, "found alias set %d\n", (int) alias_set);
1092 if (bitmap_bit_p (clear_alias_sets, alias_set))
1094 struct clear_alias_mode_holder *entry
1095 = clear_alias_set_lookup (alias_set);
1097 /* If the modes do not match, we cannot process this set. */
1098 if (entry->mode != GET_MODE (mem))
1102 "disqualifying alias set %d, (%s) != (%s)\n",
1103 (int) alias_set, GET_MODE_NAME (entry->mode),
1104 GET_MODE_NAME (GET_MODE (mem)));
1106 bitmap_set_bit (disqualified_clear_alias_sets, alias_set);
1110 *alias_set_out = alias_set;
1111 *group_id = clear_alias_group->id;
1118 cselib_lookup (mem_address, address_mode, 1, GET_MODE (mem));
1122 fprintf (dump_file, " mem: ");
1123 print_inline_rtx (dump_file, mem_address, 0);
1124 fprintf (dump_file, "\n");
1127 /* First see if just canon_rtx (mem_address) is const or frame,
1128 if not, try cselib_expand_value_rtx and call canon_rtx on that. */
1130 for (expanded = 0; expanded < 2; expanded++)
1134 /* Use cselib to replace all of the reg references with the full
1135 expression. This will take care of the case where we have
1137 r_x = base + offset;
1142 val = *(base + offset); */
1144 expanded_address = cselib_expand_value_rtx (mem_address,
1147 /* If this fails, just go with the address from first
1149 if (!expanded_address)
1153 expanded_address = mem_address;
1155 /* Split the address into canonical BASE + OFFSET terms. */
1156 address = canon_rtx (expanded_address);
1164 fprintf (dump_file, "\n after cselib_expand address: ");
1165 print_inline_rtx (dump_file, expanded_address, 0);
1166 fprintf (dump_file, "\n");
1169 fprintf (dump_file, "\n after canon_rtx address: ");
1170 print_inline_rtx (dump_file, address, 0);
1171 fprintf (dump_file, "\n");
1174 if (GET_CODE (address) == CONST)
1175 address = XEXP (address, 0);
1177 if (GET_CODE (address) == PLUS
1178 && CONST_INT_P (XEXP (address, 1)))
1180 *offset = INTVAL (XEXP (address, 1));
1181 address = XEXP (address, 0);
1184 if (ADDR_SPACE_GENERIC_P (MEM_ADDR_SPACE (mem))
1185 && const_or_frame_p (address))
1187 group_info_t group = get_group_info (address);
1190 fprintf (dump_file, " gid=%d offset=%d \n",
1191 group->id, (int)*offset);
1193 *group_id = group->id;
1198 *base = cselib_lookup (address, address_mode, true, GET_MODE (mem));
1204 fprintf (dump_file, " no cselib val - should be a wild read.\n");
1208 fprintf (dump_file, " varying cselib base=%u:%u offset = %d\n",
1209 (*base)->uid, (*base)->hash, (int)*offset);
1214 /* Clear the rhs field from the active_local_stores array. */
1217 clear_rhs_from_active_local_stores (void)
1219 insn_info_t ptr = active_local_stores;
1223 store_info_t store_info = ptr->store_rec;
1224 /* Skip the clobbers. */
1225 while (!store_info->is_set)
1226 store_info = store_info->next;
1228 store_info->rhs = NULL;
1229 store_info->const_rhs = NULL;
1231 ptr = ptr->next_local_store;
1236 /* Mark byte POS bytes from the beginning of store S_INFO as unneeded. */
1239 set_position_unneeded (store_info_t s_info, int pos)
1241 if (__builtin_expect (s_info->is_large, false))
1243 if (bitmap_set_bit (s_info->positions_needed.large.bmap, pos))
1244 s_info->positions_needed.large.count++;
1247 s_info->positions_needed.small_bitmask
1248 &= ~(((unsigned HOST_WIDE_INT) 1) << pos);
1251 /* Mark the whole store S_INFO as unneeded. */
1254 set_all_positions_unneeded (store_info_t s_info)
1256 if (__builtin_expect (s_info->is_large, false))
1258 int pos, end = s_info->end - s_info->begin;
1259 for (pos = 0; pos < end; pos++)
1260 bitmap_set_bit (s_info->positions_needed.large.bmap, pos);
1261 s_info->positions_needed.large.count = end;
1264 s_info->positions_needed.small_bitmask = (unsigned HOST_WIDE_INT) 0;
1267 /* Return TRUE if any bytes from S_INFO store are needed. */
1270 any_positions_needed_p (store_info_t s_info)
1272 if (__builtin_expect (s_info->is_large, false))
1273 return (s_info->positions_needed.large.count
1274 < s_info->end - s_info->begin);
1276 return (s_info->positions_needed.small_bitmask
1277 != (unsigned HOST_WIDE_INT) 0);
1280 /* Return TRUE if all bytes START through START+WIDTH-1 from S_INFO
1281 store are needed. */
1284 all_positions_needed_p (store_info_t s_info, int start, int width)
1286 if (__builtin_expect (s_info->is_large, false))
1288 int end = start + width;
1290 if (bitmap_bit_p (s_info->positions_needed.large.bmap, start++))
1296 unsigned HOST_WIDE_INT mask = lowpart_bitmask (width) << start;
1297 return (s_info->positions_needed.small_bitmask & mask) == mask;
1302 static rtx get_stored_val (store_info_t, enum machine_mode, HOST_WIDE_INT,
1303 HOST_WIDE_INT, basic_block, bool);
1306 /* BODY is an instruction pattern that belongs to INSN. Return 1 if
1307 there is a candidate store, after adding it to the appropriate
1308 local store group if so. */
1311 record_store (rtx body, bb_info_t bb_info)
1313 rtx mem, rhs, const_rhs, mem_addr;
1314 HOST_WIDE_INT offset = 0;
1315 HOST_WIDE_INT width = 0;
1316 alias_set_type spill_alias_set;
1317 insn_info_t insn_info = bb_info->last_insn;
1318 store_info_t store_info = NULL;
1320 cselib_val *base = NULL;
1321 insn_info_t ptr, last, redundant_reason;
1322 bool store_is_unused;
1324 if (GET_CODE (body) != SET && GET_CODE (body) != CLOBBER)
1327 mem = SET_DEST (body);
1329 /* If this is not used, then this cannot be used to keep the insn
1330 from being deleted. On the other hand, it does provide something
1331 that can be used to prove that another store is dead. */
1333 = (find_reg_note (insn_info->insn, REG_UNUSED, mem) != NULL);
1335 /* Check whether that value is a suitable memory location. */
1338 /* If the set or clobber is unused, then it does not effect our
1339 ability to get rid of the entire insn. */
1340 if (!store_is_unused)
1341 insn_info->cannot_delete = true;
1345 /* At this point we know mem is a mem. */
1346 if (GET_MODE (mem) == BLKmode)
1348 if (GET_CODE (XEXP (mem, 0)) == SCRATCH)
1351 fprintf (dump_file, " adding wild read for (clobber (mem:BLK (scratch))\n");
1352 add_wild_read (bb_info);
1353 insn_info->cannot_delete = true;
1356 /* Handle (set (mem:BLK (addr) [... S36 ...]) (const_int 0))
1357 as memset (addr, 0, 36); */
1358 else if (!MEM_SIZE (mem)
1359 || !CONST_INT_P (MEM_SIZE (mem))
1360 || GET_CODE (body) != SET
1361 || INTVAL (MEM_SIZE (mem)) <= 0
1362 || INTVAL (MEM_SIZE (mem)) > MAX_OFFSET
1363 || !CONST_INT_P (SET_SRC (body)))
1365 if (!store_is_unused)
1367 /* If the set or clobber is unused, then it does not effect our
1368 ability to get rid of the entire insn. */
1369 insn_info->cannot_delete = true;
1370 clear_rhs_from_active_local_stores ();
1376 /* We can still process a volatile mem, we just cannot delete it. */
1377 if (MEM_VOLATILE_P (mem))
1378 insn_info->cannot_delete = true;
1380 if (!canon_address (mem, &spill_alias_set, &group_id, &offset, &base))
1382 clear_rhs_from_active_local_stores ();
1386 if (GET_MODE (mem) == BLKmode)
1387 width = INTVAL (MEM_SIZE (mem));
1390 width = GET_MODE_SIZE (GET_MODE (mem));
1391 gcc_assert ((unsigned) width <= HOST_BITS_PER_WIDE_INT);
1394 if (spill_alias_set)
1396 bitmap store1 = clear_alias_group->store1_p;
1397 bitmap store2 = clear_alias_group->store2_p;
1399 gcc_assert (GET_MODE (mem) != BLKmode);
1401 if (!bitmap_set_bit (store1, spill_alias_set))
1402 bitmap_set_bit (store2, spill_alias_set);
1404 if (clear_alias_group->offset_map_size_p < spill_alias_set)
1405 clear_alias_group->offset_map_size_p = spill_alias_set;
1407 store_info = (store_info_t) pool_alloc (rtx_store_info_pool);
1410 fprintf (dump_file, " processing spill store %d(%s)\n",
1411 (int) spill_alias_set, GET_MODE_NAME (GET_MODE (mem)));
1413 else if (group_id >= 0)
1415 /* In the restrictive case where the base is a constant or the
1416 frame pointer we can do global analysis. */
1419 = VEC_index (group_info_t, rtx_group_vec, group_id);
1420 tree expr = MEM_EXPR (mem);
1422 store_info = (store_info_t) pool_alloc (rtx_store_info_pool);
1423 set_usage_bits (group, offset, width, expr);
1426 fprintf (dump_file, " processing const base store gid=%d[%d..%d)\n",
1427 group_id, (int)offset, (int)(offset+width));
1431 rtx base_term = find_base_term (XEXP (mem, 0));
1433 || (GET_CODE (base_term) == ADDRESS
1434 && GET_MODE (base_term) == Pmode
1435 && XEXP (base_term, 0) == stack_pointer_rtx))
1436 insn_info->stack_pointer_based = true;
1437 insn_info->contains_cselib_groups = true;
1439 store_info = (store_info_t) pool_alloc (cse_store_info_pool);
1443 fprintf (dump_file, " processing cselib store [%d..%d)\n",
1444 (int)offset, (int)(offset+width));
1447 const_rhs = rhs = NULL_RTX;
1448 if (GET_CODE (body) == SET
1449 /* No place to keep the value after ra. */
1450 && !reload_completed
1451 && (REG_P (SET_SRC (body))
1452 || GET_CODE (SET_SRC (body)) == SUBREG
1453 || CONSTANT_P (SET_SRC (body)))
1454 && !MEM_VOLATILE_P (mem)
1455 /* Sometimes the store and reload is used for truncation and
1457 && !(FLOAT_MODE_P (GET_MODE (mem)) && (flag_float_store)))
1459 rhs = SET_SRC (body);
1460 if (CONSTANT_P (rhs))
1462 else if (body == PATTERN (insn_info->insn))
1464 rtx tem = find_reg_note (insn_info->insn, REG_EQUAL, NULL_RTX);
1465 if (tem && CONSTANT_P (XEXP (tem, 0)))
1466 const_rhs = XEXP (tem, 0);
1468 if (const_rhs == NULL_RTX && REG_P (rhs))
1470 rtx tem = cselib_expand_value_rtx (rhs, scratch, 5);
1472 if (tem && CONSTANT_P (tem))
1477 /* Check to see if this stores causes some other stores to be
1479 ptr = active_local_stores;
1481 redundant_reason = NULL;
1482 mem = canon_rtx (mem);
1483 /* For alias_set != 0 canon_true_dependence should be never called. */
1484 if (spill_alias_set)
1485 mem_addr = NULL_RTX;
1489 mem_addr = base->val_rtx;
1493 = VEC_index (group_info_t, rtx_group_vec, group_id);
1494 mem_addr = group->canon_base_addr;
1497 mem_addr = plus_constant (mem_addr, offset);
1502 insn_info_t next = ptr->next_local_store;
1503 store_info_t s_info = ptr->store_rec;
1506 /* Skip the clobbers. We delete the active insn if this insn
1507 shadows the set. To have been put on the active list, it
1508 has exactly on set. */
1509 while (!s_info->is_set)
1510 s_info = s_info->next;
1512 if (s_info->alias_set != spill_alias_set)
1514 else if (s_info->alias_set)
1516 struct clear_alias_mode_holder *entry
1517 = clear_alias_set_lookup (s_info->alias_set);
1518 /* Generally, spills cannot be processed if and of the
1519 references to the slot have a different mode. But if
1520 we are in the same block and mode is exactly the same
1521 between this store and one before in the same block,
1522 we can still delete it. */
1523 if ((GET_MODE (mem) == GET_MODE (s_info->mem))
1524 && (GET_MODE (mem) == entry->mode))
1527 set_all_positions_unneeded (s_info);
1530 fprintf (dump_file, " trying spill store in insn=%d alias_set=%d\n",
1531 INSN_UID (ptr->insn), (int) s_info->alias_set);
1533 else if ((s_info->group_id == group_id)
1534 && (s_info->cse_base == base))
1538 fprintf (dump_file, " trying store in insn=%d gid=%d[%d..%d)\n",
1539 INSN_UID (ptr->insn), s_info->group_id,
1540 (int)s_info->begin, (int)s_info->end);
1542 /* Even if PTR won't be eliminated as unneeded, if both
1543 PTR and this insn store the same constant value, we might
1544 eliminate this insn instead. */
1545 if (s_info->const_rhs
1547 && offset >= s_info->begin
1548 && offset + width <= s_info->end
1549 && all_positions_needed_p (s_info, offset - s_info->begin,
1552 if (GET_MODE (mem) == BLKmode)
1554 if (GET_MODE (s_info->mem) == BLKmode
1555 && s_info->const_rhs == const_rhs)
1556 redundant_reason = ptr;
1558 else if (s_info->const_rhs == const0_rtx
1559 && const_rhs == const0_rtx)
1560 redundant_reason = ptr;
1565 val = get_stored_val (s_info, GET_MODE (mem),
1566 offset, offset + width,
1567 BLOCK_FOR_INSN (insn_info->insn),
1569 if (get_insns () != NULL)
1572 if (val && rtx_equal_p (val, const_rhs))
1573 redundant_reason = ptr;
1577 for (i = MAX (offset, s_info->begin);
1578 i < offset + width && i < s_info->end;
1580 set_position_unneeded (s_info, i - s_info->begin);
1582 else if (s_info->rhs)
1583 /* Need to see if it is possible for this store to overwrite
1584 the value of store_info. If it is, set the rhs to NULL to
1585 keep it from being used to remove a load. */
1587 if (canon_true_dependence (s_info->mem,
1588 GET_MODE (s_info->mem),
1590 mem, mem_addr, rtx_varies_p))
1593 s_info->const_rhs = NULL;
1597 /* An insn can be deleted if every position of every one of
1598 its s_infos is zero. */
1599 if (any_positions_needed_p (s_info))
1604 insn_info_t insn_to_delete = ptr;
1606 active_local_stores_len--;
1608 last->next_local_store = ptr->next_local_store;
1610 active_local_stores = ptr->next_local_store;
1612 if (!insn_to_delete->cannot_delete)
1613 delete_dead_store_insn (insn_to_delete);
1621 /* Finish filling in the store_info. */
1622 store_info->next = insn_info->store_rec;
1623 insn_info->store_rec = store_info;
1624 store_info->mem = mem;
1625 store_info->alias_set = spill_alias_set;
1626 store_info->mem_addr = mem_addr;
1627 store_info->cse_base = base;
1628 if (width > HOST_BITS_PER_WIDE_INT)
1630 store_info->is_large = true;
1631 store_info->positions_needed.large.count = 0;
1632 store_info->positions_needed.large.bmap = BITMAP_ALLOC (NULL);
1636 store_info->is_large = false;
1637 store_info->positions_needed.small_bitmask = lowpart_bitmask (width);
1639 store_info->group_id = group_id;
1640 store_info->begin = offset;
1641 store_info->end = offset + width;
1642 store_info->is_set = GET_CODE (body) == SET;
1643 store_info->rhs = rhs;
1644 store_info->const_rhs = const_rhs;
1645 store_info->redundant_reason = redundant_reason;
1647 /* If this is a clobber, we return 0. We will only be able to
1648 delete this insn if there is only one store USED store, but we
1649 can use the clobber to delete other stores earlier. */
1650 return store_info->is_set ? 1 : 0;
1655 dump_insn_info (const char * start, insn_info_t insn_info)
1657 fprintf (dump_file, "%s insn=%d %s\n", start,
1658 INSN_UID (insn_info->insn),
1659 insn_info->store_rec ? "has store" : "naked");
1663 /* If the modes are different and the value's source and target do not
1664 line up, we need to extract the value from lower part of the rhs of
1665 the store, shift it, and then put it into a form that can be shoved
1666 into the read_insn. This function generates a right SHIFT of a
1667 value that is at least ACCESS_SIZE bytes wide of READ_MODE. The
1668 shift sequence is returned or NULL if we failed to find a
1672 find_shift_sequence (int access_size,
1673 store_info_t store_info,
1674 enum machine_mode read_mode,
1675 int shift, bool speed, bool require_cst)
1677 enum machine_mode store_mode = GET_MODE (store_info->mem);
1678 enum machine_mode new_mode;
1679 rtx read_reg = NULL;
1681 /* Some machines like the x86 have shift insns for each size of
1682 operand. Other machines like the ppc or the ia-64 may only have
1683 shift insns that shift values within 32 or 64 bit registers.
1684 This loop tries to find the smallest shift insn that will right
1685 justify the value we want to read but is available in one insn on
1688 for (new_mode = smallest_mode_for_size (access_size * BITS_PER_UNIT,
1690 GET_MODE_BITSIZE (new_mode) <= BITS_PER_WORD;
1691 new_mode = GET_MODE_WIDER_MODE (new_mode))
1693 rtx target, new_reg, shift_seq, insn, new_lhs;
1696 /* If a constant was stored into memory, try to simplify it here,
1697 otherwise the cost of the shift might preclude this optimization
1698 e.g. at -Os, even when no actual shift will be needed. */
1699 if (store_info->const_rhs)
1701 unsigned int byte = subreg_lowpart_offset (new_mode, store_mode);
1702 rtx ret = simplify_subreg (new_mode, store_info->const_rhs,
1704 if (ret && CONSTANT_P (ret))
1706 ret = simplify_const_binary_operation (LSHIFTRT, new_mode,
1707 ret, GEN_INT (shift));
1708 if (ret && CONSTANT_P (ret))
1710 byte = subreg_lowpart_offset (read_mode, new_mode);
1711 ret = simplify_subreg (read_mode, ret, new_mode, byte);
1712 if (ret && CONSTANT_P (ret)
1713 && rtx_cost (ret, SET, speed) <= COSTS_N_INSNS (1))
1722 /* Try a wider mode if truncating the store mode to NEW_MODE
1723 requires a real instruction. */
1724 if (GET_MODE_BITSIZE (new_mode) < GET_MODE_BITSIZE (store_mode)
1725 && !TRULY_NOOP_TRUNCATION_MODES_P (new_mode, store_mode))
1728 /* Also try a wider mode if the necessary punning is either not
1729 desirable or not possible. */
1730 if (!CONSTANT_P (store_info->rhs)
1731 && !MODES_TIEABLE_P (new_mode, store_mode))
1734 new_reg = gen_reg_rtx (new_mode);
1738 /* In theory we could also check for an ashr. Ian Taylor knows
1739 of one dsp where the cost of these two was not the same. But
1740 this really is a rare case anyway. */
1741 target = expand_binop (new_mode, lshr_optab, new_reg,
1742 GEN_INT (shift), new_reg, 1, OPTAB_DIRECT);
1744 shift_seq = get_insns ();
1747 if (target != new_reg || shift_seq == NULL)
1751 for (insn = shift_seq; insn != NULL_RTX; insn = NEXT_INSN (insn))
1753 cost += insn_rtx_cost (PATTERN (insn), speed);
1755 /* The computation up to here is essentially independent
1756 of the arguments and could be precomputed. It may
1757 not be worth doing so. We could precompute if
1758 worthwhile or at least cache the results. The result
1759 technically depends on both SHIFT and ACCESS_SIZE,
1760 but in practice the answer will depend only on ACCESS_SIZE. */
1762 if (cost > COSTS_N_INSNS (1))
1765 new_lhs = extract_low_bits (new_mode, store_mode,
1766 copy_rtx (store_info->rhs));
1767 if (new_lhs == NULL_RTX)
1770 /* We found an acceptable shift. Generate a move to
1771 take the value from the store and put it into the
1772 shift pseudo, then shift it, then generate another
1773 move to put in into the target of the read. */
1774 emit_move_insn (new_reg, new_lhs);
1775 emit_insn (shift_seq);
1776 read_reg = extract_low_bits (read_mode, new_mode, new_reg);
1784 /* Call back for note_stores to find the hard regs set or clobbered by
1785 insn. Data is a bitmap of the hardregs set so far. */
1788 look_for_hardregs (rtx x, const_rtx pat ATTRIBUTE_UNUSED, void *data)
1790 bitmap regs_set = (bitmap) data;
1793 && HARD_REGISTER_P (x))
1795 unsigned int regno = REGNO (x);
1796 bitmap_set_range (regs_set, regno,
1797 hard_regno_nregs[regno][GET_MODE (x)]);
1801 /* Helper function for replace_read and record_store.
1802 Attempt to return a value stored in STORE_INFO, from READ_BEGIN
1803 to one before READ_END bytes read in READ_MODE. Return NULL
1804 if not successful. If REQUIRE_CST is true, return always constant. */
1807 get_stored_val (store_info_t store_info, enum machine_mode read_mode,
1808 HOST_WIDE_INT read_begin, HOST_WIDE_INT read_end,
1809 basic_block bb, bool require_cst)
1811 enum machine_mode store_mode = GET_MODE (store_info->mem);
1813 int access_size; /* In bytes. */
1816 /* To get here the read is within the boundaries of the write so
1817 shift will never be negative. Start out with the shift being in
1819 if (store_mode == BLKmode)
1821 else if (BYTES_BIG_ENDIAN)
1822 shift = store_info->end - read_end;
1824 shift = read_begin - store_info->begin;
1826 access_size = shift + GET_MODE_SIZE (read_mode);
1828 /* From now on it is bits. */
1829 shift *= BITS_PER_UNIT;
1832 read_reg = find_shift_sequence (access_size, store_info, read_mode, shift,
1833 optimize_bb_for_speed_p (bb),
1835 else if (store_mode == BLKmode)
1837 /* The store is a memset (addr, const_val, const_size). */
1838 gcc_assert (CONST_INT_P (store_info->rhs));
1839 store_mode = int_mode_for_mode (read_mode);
1840 if (store_mode == BLKmode)
1841 read_reg = NULL_RTX;
1842 else if (store_info->rhs == const0_rtx)
1843 read_reg = extract_low_bits (read_mode, store_mode, const0_rtx);
1844 else if (GET_MODE_BITSIZE (store_mode) > HOST_BITS_PER_WIDE_INT
1845 || BITS_PER_UNIT >= HOST_BITS_PER_WIDE_INT)
1846 read_reg = NULL_RTX;
1849 unsigned HOST_WIDE_INT c
1850 = INTVAL (store_info->rhs)
1851 & (((HOST_WIDE_INT) 1 << BITS_PER_UNIT) - 1);
1852 int shift = BITS_PER_UNIT;
1853 while (shift < HOST_BITS_PER_WIDE_INT)
1858 read_reg = GEN_INT (trunc_int_for_mode (c, store_mode));
1859 read_reg = extract_low_bits (read_mode, store_mode, read_reg);
1862 else if (store_info->const_rhs
1864 || GET_MODE_CLASS (read_mode) != GET_MODE_CLASS (store_mode)))
1865 read_reg = extract_low_bits (read_mode, store_mode,
1866 copy_rtx (store_info->const_rhs));
1868 read_reg = extract_low_bits (read_mode, store_mode,
1869 copy_rtx (store_info->rhs));
1870 if (require_cst && read_reg && !CONSTANT_P (read_reg))
1871 read_reg = NULL_RTX;
1875 /* Take a sequence of:
1898 Depending on the alignment and the mode of the store and
1902 The STORE_INFO and STORE_INSN are for the store and READ_INFO
1903 and READ_INSN are for the read. Return true if the replacement
1907 replace_read (store_info_t store_info, insn_info_t store_insn,
1908 read_info_t read_info, insn_info_t read_insn, rtx *loc,
1911 enum machine_mode store_mode = GET_MODE (store_info->mem);
1912 enum machine_mode read_mode = GET_MODE (read_info->mem);
1913 rtx insns, this_insn, read_reg;
1919 /* Create a sequence of instructions to set up the read register.
1920 This sequence goes immediately before the store and its result
1921 is read by the load.
1923 We need to keep this in perspective. We are replacing a read
1924 with a sequence of insns, but the read will almost certainly be
1925 in cache, so it is not going to be an expensive one. Thus, we
1926 are not willing to do a multi insn shift or worse a subroutine
1927 call to get rid of the read. */
1929 fprintf (dump_file, "trying to replace %smode load in insn %d"
1930 " from %smode store in insn %d\n",
1931 GET_MODE_NAME (read_mode), INSN_UID (read_insn->insn),
1932 GET_MODE_NAME (store_mode), INSN_UID (store_insn->insn));
1934 bb = BLOCK_FOR_INSN (read_insn->insn);
1935 read_reg = get_stored_val (store_info,
1936 read_mode, read_info->begin, read_info->end,
1938 if (read_reg == NULL_RTX)
1942 fprintf (dump_file, " -- could not extract bits of stored value\n");
1945 /* Force the value into a new register so that it won't be clobbered
1946 between the store and the load. */
1947 read_reg = copy_to_mode_reg (read_mode, read_reg);
1948 insns = get_insns ();
1951 if (insns != NULL_RTX)
1953 /* Now we have to scan the set of new instructions to see if the
1954 sequence contains and sets of hardregs that happened to be
1955 live at this point. For instance, this can happen if one of
1956 the insns sets the CC and the CC happened to be live at that
1957 point. This does occasionally happen, see PR 37922. */
1958 bitmap regs_set = BITMAP_ALLOC (NULL);
1960 for (this_insn = insns; this_insn != NULL_RTX; this_insn = NEXT_INSN (this_insn))
1961 note_stores (PATTERN (this_insn), look_for_hardregs, regs_set);
1963 bitmap_and_into (regs_set, regs_live);
1964 if (!bitmap_empty_p (regs_set))
1969 "abandoning replacement because sequence clobbers live hardregs:");
1970 df_print_regset (dump_file, regs_set);
1973 BITMAP_FREE (regs_set);
1976 BITMAP_FREE (regs_set);
1979 if (validate_change (read_insn->insn, loc, read_reg, 0))
1981 deferred_change_t deferred_change =
1982 (deferred_change_t) pool_alloc (deferred_change_pool);
1984 /* Insert this right before the store insn where it will be safe
1985 from later insns that might change it before the read. */
1986 emit_insn_before (insns, store_insn->insn);
1988 /* And now for the kludge part: cselib croaks if you just
1989 return at this point. There are two reasons for this:
1991 1) Cselib has an idea of how many pseudos there are and
1992 that does not include the new ones we just added.
1994 2) Cselib does not know about the move insn we added
1995 above the store_info, and there is no way to tell it
1996 about it, because it has "moved on".
1998 Problem (1) is fixable with a certain amount of engineering.
1999 Problem (2) is requires starting the bb from scratch. This
2002 So we are just going to have to lie. The move/extraction
2003 insns are not really an issue, cselib did not see them. But
2004 the use of the new pseudo read_insn is a real problem because
2005 cselib has not scanned this insn. The way that we solve this
2006 problem is that we are just going to put the mem back for now
2007 and when we are finished with the block, we undo this. We
2008 keep a table of mems to get rid of. At the end of the basic
2009 block we can put them back. */
2011 *loc = read_info->mem;
2012 deferred_change->next = deferred_change_list;
2013 deferred_change_list = deferred_change;
2014 deferred_change->loc = loc;
2015 deferred_change->reg = read_reg;
2017 /* Get rid of the read_info, from the point of view of the
2018 rest of dse, play like this read never happened. */
2019 read_insn->read_rec = read_info->next;
2020 pool_free (read_info_pool, read_info);
2023 fprintf (dump_file, " -- replaced the loaded MEM with ");
2024 print_simple_rtl (dump_file, read_reg);
2025 fprintf (dump_file, "\n");
2033 fprintf (dump_file, " -- replacing the loaded MEM with ");
2034 print_simple_rtl (dump_file, read_reg);
2035 fprintf (dump_file, " led to an invalid instruction\n");
2041 /* A for_each_rtx callback in which DATA is the bb_info. Check to see
2042 if LOC is a mem and if it is look at the address and kill any
2043 appropriate stores that may be active. */
2046 check_mem_read_rtx (rtx *loc, void *data)
2048 rtx mem = *loc, mem_addr;
2050 insn_info_t insn_info;
2051 HOST_WIDE_INT offset = 0;
2052 HOST_WIDE_INT width = 0;
2053 alias_set_type spill_alias_set = 0;
2054 cselib_val *base = NULL;
2056 read_info_t read_info;
2058 if (!mem || !MEM_P (mem))
2061 bb_info = (bb_info_t) data;
2062 insn_info = bb_info->last_insn;
2064 if ((MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER)
2065 || (MEM_VOLATILE_P (mem)))
2068 fprintf (dump_file, " adding wild read, volatile or barrier.\n");
2069 add_wild_read (bb_info);
2070 insn_info->cannot_delete = true;
2074 /* If it is reading readonly mem, then there can be no conflict with
2076 if (MEM_READONLY_P (mem))
2079 if (!canon_address (mem, &spill_alias_set, &group_id, &offset, &base))
2082 fprintf (dump_file, " adding wild read, canon_address failure.\n");
2083 add_wild_read (bb_info);
2087 if (GET_MODE (mem) == BLKmode)
2090 width = GET_MODE_SIZE (GET_MODE (mem));
2092 read_info = (read_info_t) pool_alloc (read_info_pool);
2093 read_info->group_id = group_id;
2094 read_info->mem = mem;
2095 read_info->alias_set = spill_alias_set;
2096 read_info->begin = offset;
2097 read_info->end = offset + width;
2098 read_info->next = insn_info->read_rec;
2099 insn_info->read_rec = read_info;
2100 /* For alias_set != 0 canon_true_dependence should be never called. */
2101 if (spill_alias_set)
2102 mem_addr = NULL_RTX;
2106 mem_addr = base->val_rtx;
2110 = VEC_index (group_info_t, rtx_group_vec, group_id);
2111 mem_addr = group->canon_base_addr;
2114 mem_addr = plus_constant (mem_addr, offset);
2117 /* We ignore the clobbers in store_info. The is mildly aggressive,
2118 but there really should not be a clobber followed by a read. */
2120 if (spill_alias_set)
2122 insn_info_t i_ptr = active_local_stores;
2123 insn_info_t last = NULL;
2126 fprintf (dump_file, " processing spill load %d\n",
2127 (int) spill_alias_set);
2131 store_info_t store_info = i_ptr->store_rec;
2133 /* Skip the clobbers. */
2134 while (!store_info->is_set)
2135 store_info = store_info->next;
2137 if (store_info->alias_set == spill_alias_set)
2140 dump_insn_info ("removing from active", i_ptr);
2142 active_local_stores_len--;
2144 last->next_local_store = i_ptr->next_local_store;
2146 active_local_stores = i_ptr->next_local_store;
2150 i_ptr = i_ptr->next_local_store;
2153 else if (group_id >= 0)
2155 /* This is the restricted case where the base is a constant or
2156 the frame pointer and offset is a constant. */
2157 insn_info_t i_ptr = active_local_stores;
2158 insn_info_t last = NULL;
2163 fprintf (dump_file, " processing const load gid=%d[BLK]\n",
2166 fprintf (dump_file, " processing const load gid=%d[%d..%d)\n",
2167 group_id, (int)offset, (int)(offset+width));
2172 bool remove = false;
2173 store_info_t store_info = i_ptr->store_rec;
2175 /* Skip the clobbers. */
2176 while (!store_info->is_set)
2177 store_info = store_info->next;
2179 /* There are three cases here. */
2180 if (store_info->group_id < 0)
2181 /* We have a cselib store followed by a read from a
2184 = canon_true_dependence (store_info->mem,
2185 GET_MODE (store_info->mem),
2186 store_info->mem_addr,
2187 mem, mem_addr, rtx_varies_p);
2189 else if (group_id == store_info->group_id)
2191 /* This is a block mode load. We may get lucky and
2192 canon_true_dependence may save the day. */
2195 = canon_true_dependence (store_info->mem,
2196 GET_MODE (store_info->mem),
2197 store_info->mem_addr,
2198 mem, mem_addr, rtx_varies_p);
2200 /* If this read is just reading back something that we just
2201 stored, rewrite the read. */
2205 && offset >= store_info->begin
2206 && offset + width <= store_info->end
2207 && all_positions_needed_p (store_info,
2208 offset - store_info->begin,
2210 && replace_read (store_info, i_ptr, read_info,
2211 insn_info, loc, bb_info->regs_live))
2214 /* The bases are the same, just see if the offsets
2216 if ((offset < store_info->end)
2217 && (offset + width > store_info->begin))
2223 The else case that is missing here is that the
2224 bases are constant but different. There is nothing
2225 to do here because there is no overlap. */
2230 dump_insn_info ("removing from active", i_ptr);
2232 active_local_stores_len--;
2234 last->next_local_store = i_ptr->next_local_store;
2236 active_local_stores = i_ptr->next_local_store;
2240 i_ptr = i_ptr->next_local_store;
2245 insn_info_t i_ptr = active_local_stores;
2246 insn_info_t last = NULL;
2249 fprintf (dump_file, " processing cselib load mem:");
2250 print_inline_rtx (dump_file, mem, 0);
2251 fprintf (dump_file, "\n");
2256 bool remove = false;
2257 store_info_t store_info = i_ptr->store_rec;
2260 fprintf (dump_file, " processing cselib load against insn %d\n",
2261 INSN_UID (i_ptr->insn));
2263 /* Skip the clobbers. */
2264 while (!store_info->is_set)
2265 store_info = store_info->next;
2267 /* If this read is just reading back something that we just
2268 stored, rewrite the read. */
2270 && store_info->group_id == -1
2271 && store_info->cse_base == base
2273 && offset >= store_info->begin
2274 && offset + width <= store_info->end
2275 && all_positions_needed_p (store_info,
2276 offset - store_info->begin, width)
2277 && replace_read (store_info, i_ptr, read_info, insn_info, loc,
2278 bb_info->regs_live))
2281 if (!store_info->alias_set)
2282 remove = canon_true_dependence (store_info->mem,
2283 GET_MODE (store_info->mem),
2284 store_info->mem_addr,
2285 mem, mem_addr, rtx_varies_p);
2290 dump_insn_info ("removing from active", i_ptr);
2292 active_local_stores_len--;
2294 last->next_local_store = i_ptr->next_local_store;
2296 active_local_stores = i_ptr->next_local_store;
2300 i_ptr = i_ptr->next_local_store;
2306 /* A for_each_rtx callback in which DATA points the INSN_INFO for
2307 as check_mem_read_rtx. Nullify the pointer if i_m_r_m_r returns
2308 true for any part of *LOC. */
2311 check_mem_read_use (rtx *loc, void *data)
2313 for_each_rtx (loc, check_mem_read_rtx, data);
2317 /* Get arguments passed to CALL_INSN. Return TRUE if successful.
2318 So far it only handles arguments passed in registers. */
2321 get_call_args (rtx call_insn, tree fn, rtx *args, int nargs)
2323 CUMULATIVE_ARGS args_so_far_v;
2324 cumulative_args_t args_so_far;
2328 INIT_CUMULATIVE_ARGS (args_so_far_v, TREE_TYPE (fn), NULL_RTX, 0, 3);
2329 args_so_far = pack_cumulative_args (&args_so_far_v);
2331 arg = TYPE_ARG_TYPES (TREE_TYPE (fn));
2333 arg != void_list_node && idx < nargs;
2334 arg = TREE_CHAIN (arg), idx++)
2336 enum machine_mode mode = TYPE_MODE (TREE_VALUE (arg));
2338 reg = targetm.calls.function_arg (args_so_far, mode, NULL_TREE, true);
2339 if (!reg || !REG_P (reg) || GET_MODE (reg) != mode
2340 || GET_MODE_CLASS (mode) != MODE_INT)
2343 for (link = CALL_INSN_FUNCTION_USAGE (call_insn);
2345 link = XEXP (link, 1))
2346 if (GET_CODE (XEXP (link, 0)) == USE)
2348 args[idx] = XEXP (XEXP (link, 0), 0);
2349 if (REG_P (args[idx])
2350 && REGNO (args[idx]) == REGNO (reg)
2351 && (GET_MODE (args[idx]) == mode
2352 || (GET_MODE_CLASS (GET_MODE (args[idx])) == MODE_INT
2353 && (GET_MODE_SIZE (GET_MODE (args[idx]))
2355 && (GET_MODE_SIZE (GET_MODE (args[idx]))
2356 > GET_MODE_SIZE (mode)))))
2362 tmp = cselib_expand_value_rtx (args[idx], scratch, 5);
2363 if (GET_MODE (args[idx]) != mode)
2365 if (!tmp || !CONST_INT_P (tmp))
2367 tmp = GEN_INT (trunc_int_for_mode (INTVAL (tmp), mode));
2372 targetm.calls.function_arg_advance (args_so_far, mode, NULL_TREE, true);
2374 if (arg != void_list_node || idx != nargs)
2380 /* Apply record_store to all candidate stores in INSN. Mark INSN
2381 if some part of it is not a candidate store and assigns to a
2382 non-register target. */
2385 scan_insn (bb_info_t bb_info, rtx insn)
2388 insn_info_t insn_info = (insn_info_t) pool_alloc (insn_info_pool);
2390 memset (insn_info, 0, sizeof (struct insn_info));
2393 fprintf (dump_file, "\n**scanning insn=%d\n",
2396 insn_info->prev_insn = bb_info->last_insn;
2397 insn_info->insn = insn;
2398 bb_info->last_insn = insn_info;
2400 if (DEBUG_INSN_P (insn))
2402 insn_info->cannot_delete = true;
2406 /* Cselib clears the table for this case, so we have to essentially
2408 if (NONJUMP_INSN_P (insn)
2409 && GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2410 && MEM_VOLATILE_P (PATTERN (insn)))
2412 add_wild_read (bb_info);
2413 insn_info->cannot_delete = true;
2417 /* Look at all of the uses in the insn. */
2418 note_uses (&PATTERN (insn), check_mem_read_use, bb_info);
2423 tree memset_call = NULL_TREE;
2425 insn_info->cannot_delete = true;
2427 /* Const functions cannot do anything bad i.e. read memory,
2428 however, they can read their parameters which may have
2429 been pushed onto the stack.
2430 memset and bzero don't read memory either. */
2431 const_call = RTL_CONST_CALL_P (insn);
2434 rtx call = PATTERN (insn);
2435 if (GET_CODE (call) == PARALLEL)
2436 call = XVECEXP (call, 0, 0);
2437 if (GET_CODE (call) == SET)
2438 call = SET_SRC (call);
2439 if (GET_CODE (call) == CALL
2440 && MEM_P (XEXP (call, 0))
2441 && GET_CODE (XEXP (XEXP (call, 0), 0)) == SYMBOL_REF)
2443 rtx symbol = XEXP (XEXP (call, 0), 0);
2444 if (SYMBOL_REF_DECL (symbol)
2445 && TREE_CODE (SYMBOL_REF_DECL (symbol)) == FUNCTION_DECL)
2447 if ((DECL_BUILT_IN_CLASS (SYMBOL_REF_DECL (symbol))
2449 && (DECL_FUNCTION_CODE (SYMBOL_REF_DECL (symbol))
2450 == BUILT_IN_MEMSET))
2451 || SYMBOL_REF_DECL (symbol) == block_clear_fn)
2452 memset_call = SYMBOL_REF_DECL (symbol);
2456 if (const_call || memset_call)
2458 insn_info_t i_ptr = active_local_stores;
2459 insn_info_t last = NULL;
2462 fprintf (dump_file, "%s call %d\n",
2463 const_call ? "const" : "memset", INSN_UID (insn));
2465 /* See the head comment of the frame_read field. */
2466 if (reload_completed)
2467 insn_info->frame_read = true;
2469 /* Loop over the active stores and remove those which are
2470 killed by the const function call. */
2473 bool remove_store = false;
2475 /* The stack pointer based stores are always killed. */
2476 if (i_ptr->stack_pointer_based)
2477 remove_store = true;
2479 /* If the frame is read, the frame related stores are killed. */
2480 else if (insn_info->frame_read)
2482 store_info_t store_info = i_ptr->store_rec;
2484 /* Skip the clobbers. */
2485 while (!store_info->is_set)
2486 store_info = store_info->next;
2488 if (store_info->group_id >= 0
2489 && VEC_index (group_info_t, rtx_group_vec,
2490 store_info->group_id)->frame_related)
2491 remove_store = true;
2497 dump_insn_info ("removing from active", i_ptr);
2499 active_local_stores_len--;
2501 last->next_local_store = i_ptr->next_local_store;
2503 active_local_stores = i_ptr->next_local_store;
2508 i_ptr = i_ptr->next_local_store;
2514 if (get_call_args (insn, memset_call, args, 3)
2515 && CONST_INT_P (args[1])
2516 && CONST_INT_P (args[2])
2517 && INTVAL (args[2]) > 0)
2519 rtx mem = gen_rtx_MEM (BLKmode, args[0]);
2520 set_mem_size (mem, args[2]);
2521 body = gen_rtx_SET (VOIDmode, mem, args[1]);
2522 mems_found += record_store (body, bb_info);
2524 fprintf (dump_file, "handling memset as BLKmode store\n");
2525 if (mems_found == 1)
2527 if (active_local_stores_len++
2528 >= PARAM_VALUE (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES))
2530 active_local_stores_len = 1;
2531 active_local_stores = NULL;
2533 insn_info->next_local_store = active_local_stores;
2534 active_local_stores = insn_info;
2541 /* Every other call, including pure functions, may read any memory
2542 that is not relative to the frame. */
2543 add_non_frame_wild_read (bb_info);
2548 /* Assuming that there are sets in these insns, we cannot delete
2550 if ((GET_CODE (PATTERN (insn)) == CLOBBER)
2551 || volatile_refs_p (PATTERN (insn))
2552 || insn_could_throw_p (insn)
2553 || (RTX_FRAME_RELATED_P (insn))
2554 || find_reg_note (insn, REG_FRAME_RELATED_EXPR, NULL_RTX))
2555 insn_info->cannot_delete = true;
2557 body = PATTERN (insn);
2558 if (GET_CODE (body) == PARALLEL)
2561 for (i = 0; i < XVECLEN (body, 0); i++)
2562 mems_found += record_store (XVECEXP (body, 0, i), bb_info);
2565 mems_found += record_store (body, bb_info);
2568 fprintf (dump_file, "mems_found = %d, cannot_delete = %s\n",
2569 mems_found, insn_info->cannot_delete ? "true" : "false");
2571 /* If we found some sets of mems, add it into the active_local_stores so
2572 that it can be locally deleted if found dead or used for
2573 replace_read and redundant constant store elimination. Otherwise mark
2574 it as cannot delete. This simplifies the processing later. */
2575 if (mems_found == 1)
2577 if (active_local_stores_len++
2578 >= PARAM_VALUE (PARAM_MAX_DSE_ACTIVE_LOCAL_STORES))
2580 active_local_stores_len = 1;
2581 active_local_stores = NULL;
2583 insn_info->next_local_store = active_local_stores;
2584 active_local_stores = insn_info;
2587 insn_info->cannot_delete = true;
2591 /* Remove BASE from the set of active_local_stores. This is a
2592 callback from cselib that is used to get rid of the stores in
2593 active_local_stores. */
2596 remove_useless_values (cselib_val *base)
2598 insn_info_t insn_info = active_local_stores;
2599 insn_info_t last = NULL;
2603 store_info_t store_info = insn_info->store_rec;
2606 /* If ANY of the store_infos match the cselib group that is
2607 being deleted, then the insn can not be deleted. */
2610 if ((store_info->group_id == -1)
2611 && (store_info->cse_base == base))
2616 store_info = store_info->next;
2621 active_local_stores_len--;
2623 last->next_local_store = insn_info->next_local_store;
2625 active_local_stores = insn_info->next_local_store;
2626 free_store_info (insn_info);
2631 insn_info = insn_info->next_local_store;
2636 /* Do all of step 1. */
2642 bitmap regs_live = BITMAP_ALLOC (NULL);
2645 all_blocks = BITMAP_ALLOC (NULL);
2646 bitmap_set_bit (all_blocks, ENTRY_BLOCK);
2647 bitmap_set_bit (all_blocks, EXIT_BLOCK);
2652 bb_info_t bb_info = (bb_info_t) pool_alloc (bb_info_pool);
2654 memset (bb_info, 0, sizeof (struct bb_info));
2655 bitmap_set_bit (all_blocks, bb->index);
2656 bb_info->regs_live = regs_live;
2658 bitmap_copy (regs_live, DF_LR_IN (bb));
2659 df_simulate_initialize_forwards (bb, regs_live);
2661 bb_table[bb->index] = bb_info;
2662 cselib_discard_hook = remove_useless_values;
2664 if (bb->index >= NUM_FIXED_BLOCKS)
2669 = create_alloc_pool ("cse_store_info_pool",
2670 sizeof (struct store_info), 100);
2671 active_local_stores = NULL;
2672 active_local_stores_len = 0;
2673 cselib_clear_table ();
2675 /* Scan the insns. */
2676 FOR_BB_INSNS (bb, insn)
2679 scan_insn (bb_info, insn);
2680 cselib_process_insn (insn);
2682 df_simulate_one_insn_forwards (bb, insn, regs_live);
2685 /* This is something of a hack, because the global algorithm
2686 is supposed to take care of the case where stores go dead
2687 at the end of the function. However, the global
2688 algorithm must take a more conservative view of block
2689 mode reads than the local alg does. So to get the case
2690 where you have a store to the frame followed by a non
2691 overlapping block more read, we look at the active local
2692 stores at the end of the function and delete all of the
2693 frame and spill based ones. */
2694 if (stores_off_frame_dead_at_return
2695 && (EDGE_COUNT (bb->succs) == 0
2696 || (single_succ_p (bb)
2697 && single_succ (bb) == EXIT_BLOCK_PTR
2698 && ! crtl->calls_eh_return)))
2700 insn_info_t i_ptr = active_local_stores;
2703 store_info_t store_info = i_ptr->store_rec;
2705 /* Skip the clobbers. */
2706 while (!store_info->is_set)
2707 store_info = store_info->next;
2708 if (store_info->alias_set && !i_ptr->cannot_delete)
2709 delete_dead_store_insn (i_ptr);
2711 if (store_info->group_id >= 0)
2714 = VEC_index (group_info_t, rtx_group_vec, store_info->group_id);
2715 if (group->frame_related && !i_ptr->cannot_delete)
2716 delete_dead_store_insn (i_ptr);
2719 i_ptr = i_ptr->next_local_store;
2723 /* Get rid of the loads that were discovered in
2724 replace_read. Cselib is finished with this block. */
2725 while (deferred_change_list)
2727 deferred_change_t next = deferred_change_list->next;
2729 /* There is no reason to validate this change. That was
2731 *deferred_change_list->loc = deferred_change_list->reg;
2732 pool_free (deferred_change_pool, deferred_change_list);
2733 deferred_change_list = next;
2736 /* Get rid of all of the cselib based store_infos in this
2737 block and mark the containing insns as not being
2739 ptr = bb_info->last_insn;
2742 if (ptr->contains_cselib_groups)
2744 store_info_t s_info = ptr->store_rec;
2745 while (s_info && !s_info->is_set)
2746 s_info = s_info->next;
2748 && s_info->redundant_reason
2749 && s_info->redundant_reason->insn
2750 && !ptr->cannot_delete)
2753 fprintf (dump_file, "Locally deleting insn %d "
2754 "because insn %d stores the "
2755 "same value and couldn't be "
2757 INSN_UID (ptr->insn),
2758 INSN_UID (s_info->redundant_reason->insn));
2759 delete_dead_store_insn (ptr);
2762 s_info->redundant_reason = NULL;
2763 free_store_info (ptr);
2767 store_info_t s_info;
2769 /* Free at least positions_needed bitmaps. */
2770 for (s_info = ptr->store_rec; s_info; s_info = s_info->next)
2771 if (s_info->is_large)
2773 BITMAP_FREE (s_info->positions_needed.large.bmap);
2774 s_info->is_large = false;
2777 ptr = ptr->prev_insn;
2780 free_alloc_pool (cse_store_info_pool);
2782 bb_info->regs_live = NULL;
2785 BITMAP_FREE (regs_live);
2787 htab_empty (rtx_group_table);
2791 /*----------------------------------------------------------------------------
2794 Assign each byte position in the stores that we are going to
2795 analyze globally to a position in the bitmaps. Returns true if
2796 there are any bit positions assigned.
2797 ----------------------------------------------------------------------------*/
2800 dse_step2_init (void)
2805 FOR_EACH_VEC_ELT (group_info_t, rtx_group_vec, i, group)
2807 /* For all non stack related bases, we only consider a store to
2808 be deletable if there are two or more stores for that
2809 position. This is because it takes one store to make the
2810 other store redundant. However, for the stores that are
2811 stack related, we consider them if there is only one store
2812 for the position. We do this because the stack related
2813 stores can be deleted if their is no read between them and
2814 the end of the function.
2816 To make this work in the current framework, we take the stack
2817 related bases add all of the bits from store1 into store2.
2818 This has the effect of making the eligible even if there is
2821 if (stores_off_frame_dead_at_return && group->frame_related)
2823 bitmap_ior_into (group->store2_n, group->store1_n);
2824 bitmap_ior_into (group->store2_p, group->store1_p);
2826 fprintf (dump_file, "group %d is frame related ", i);
2829 group->offset_map_size_n++;
2830 group->offset_map_n = XNEWVEC (int, group->offset_map_size_n);
2831 group->offset_map_size_p++;
2832 group->offset_map_p = XNEWVEC (int, group->offset_map_size_p);
2833 group->process_globally = false;
2836 fprintf (dump_file, "group %d(%d+%d): ", i,
2837 (int)bitmap_count_bits (group->store2_n),
2838 (int)bitmap_count_bits (group->store2_p));
2839 bitmap_print (dump_file, group->store2_n, "n ", " ");
2840 bitmap_print (dump_file, group->store2_p, "p ", "\n");
2846 /* Init the offset tables for the normal case. */
2849 dse_step2_nospill (void)
2853 /* Position 0 is unused because 0 is used in the maps to mean
2855 current_position = 1;
2856 FOR_EACH_VEC_ELT (group_info_t, rtx_group_vec, i, group)
2861 if (group == clear_alias_group)
2864 memset (group->offset_map_n, 0, sizeof(int) * group->offset_map_size_n);
2865 memset (group->offset_map_p, 0, sizeof(int) * group->offset_map_size_p);
2866 bitmap_clear (group->group_kill);
2868 EXECUTE_IF_SET_IN_BITMAP (group->store2_n, 0, j, bi)
2870 bitmap_set_bit (group->group_kill, current_position);
2871 if (bitmap_bit_p (group->escaped_n, j))
2872 bitmap_set_bit (kill_on_calls, current_position);
2873 group->offset_map_n[j] = current_position++;
2874 group->process_globally = true;
2876 EXECUTE_IF_SET_IN_BITMAP (group->store2_p, 0, j, bi)
2878 bitmap_set_bit (group->group_kill, current_position);
2879 if (bitmap_bit_p (group->escaped_p, j))
2880 bitmap_set_bit (kill_on_calls, current_position);
2881 group->offset_map_p[j] = current_position++;
2882 group->process_globally = true;
2885 return current_position != 1;
2889 /* Init the offset tables for the spill case. */
2892 dse_step2_spill (void)
2895 group_info_t group = clear_alias_group;
2898 /* Position 0 is unused because 0 is used in the maps to mean
2900 current_position = 1;
2904 bitmap_print (dump_file, clear_alias_sets,
2905 "clear alias sets ", "\n");
2906 bitmap_print (dump_file, disqualified_clear_alias_sets,
2907 "disqualified clear alias sets ", "\n");
2910 memset (group->offset_map_n, 0, sizeof(int) * group->offset_map_size_n);
2911 memset (group->offset_map_p, 0, sizeof(int) * group->offset_map_size_p);
2912 bitmap_clear (group->group_kill);
2914 /* Remove the disqualified positions from the store2_p set. */
2915 bitmap_and_compl_into (group->store2_p, disqualified_clear_alias_sets);
2917 /* We do not need to process the store2_n set because
2918 alias_sets are always positive. */
2919 EXECUTE_IF_SET_IN_BITMAP (group->store2_p, 0, j, bi)
2921 bitmap_set_bit (group->group_kill, current_position);
2922 group->offset_map_p[j] = current_position++;
2923 group->process_globally = true;
2926 return current_position != 1;
2931 /*----------------------------------------------------------------------------
2934 Build the bit vectors for the transfer functions.
2935 ----------------------------------------------------------------------------*/
2938 /* Note that this is NOT a general purpose function. Any mem that has
2939 an alias set registered here expected to be COMPLETELY unaliased:
2940 i.e it's addresses are not and need not be examined.
2942 It is known that all references to this address will have this
2943 alias set and there are NO other references to this address in the
2946 Currently the only place that is known to be clean enough to use
2947 this interface is the code that assigns the spill locations.
2949 All of the mems that have alias_sets registered are subjected to a
2950 very powerful form of dse where function calls, volatile reads and
2951 writes, and reads from random location are not taken into account.
2953 It is also assumed that these locations go dead when the function
2954 returns. This assumption could be relaxed if there were found to
2955 be places that this assumption was not correct.
2957 The MODE is passed in and saved. The mode of each load or store to
2958 a mem with ALIAS_SET is checked against MEM. If the size of that
2959 load or store is different from MODE, processing is halted on this
2960 alias set. For the vast majority of aliases sets, all of the loads
2961 and stores will use the same mode. But vectors are treated
2962 differently: the alias set is established for the entire vector,
2963 but reload will insert loads and stores for individual elements and
2964 we do not necessarily have the information to track those separate
2965 elements. So when we see a mode mismatch, we just bail. */
2969 dse_record_singleton_alias_set (alias_set_type alias_set,
2970 enum machine_mode mode)
2972 struct clear_alias_mode_holder tmp_holder;
2973 struct clear_alias_mode_holder *entry;
2976 /* If we are not going to run dse, we need to return now or there
2977 will be problems with allocating the bitmaps. */
2978 if ((!gate_dse()) || !alias_set)
2981 if (!clear_alias_sets)
2983 clear_alias_sets = BITMAP_ALLOC (NULL);
2984 disqualified_clear_alias_sets = BITMAP_ALLOC (NULL);
2985 clear_alias_mode_table = htab_create (11, clear_alias_mode_hash,
2986 clear_alias_mode_eq, NULL);
2987 clear_alias_mode_pool = create_alloc_pool ("clear_alias_mode_pool",
2988 sizeof (struct clear_alias_mode_holder), 100);
2991 bitmap_set_bit (clear_alias_sets, alias_set);
2993 tmp_holder.alias_set = alias_set;
2995 slot = htab_find_slot (clear_alias_mode_table, &tmp_holder, INSERT);
2996 gcc_assert (*slot == NULL);
2999 (struct clear_alias_mode_holder *) pool_alloc (clear_alias_mode_pool);
3000 entry->alias_set = alias_set;
3005 /* Remove ALIAS_SET from the sets of stack slots being considered. */
3008 dse_invalidate_singleton_alias_set (alias_set_type alias_set)
3010 if ((!gate_dse()) || !alias_set)
3013 bitmap_clear_bit (clear_alias_sets, alias_set);
3017 /* Look up the bitmap index for OFFSET in GROUP_INFO. If it is not
3021 get_bitmap_index (group_info_t group_info, HOST_WIDE_INT offset)
3025 HOST_WIDE_INT offset_p = -offset;
3026 if (offset_p >= group_info->offset_map_size_n)
3028 return group_info->offset_map_n[offset_p];
3032 if (offset >= group_info->offset_map_size_p)
3034 return group_info->offset_map_p[offset];
3039 /* Process the STORE_INFOs into the bitmaps into GEN and KILL. KILL
3043 scan_stores_nospill (store_info_t store_info, bitmap gen, bitmap kill)
3048 group_info_t group_info
3049 = VEC_index (group_info_t, rtx_group_vec, store_info->group_id);
3050 if (group_info->process_globally)
3051 for (i = store_info->begin; i < store_info->end; i++)
3053 int index = get_bitmap_index (group_info, i);
3056 bitmap_set_bit (gen, index);
3058 bitmap_clear_bit (kill, index);
3061 store_info = store_info->next;
3066 /* Process the STORE_INFOs into the bitmaps into GEN and KILL. KILL
3070 scan_stores_spill (store_info_t store_info, bitmap gen, bitmap kill)
3074 if (store_info->alias_set)
3076 int index = get_bitmap_index (clear_alias_group,
3077 store_info->alias_set);
3080 bitmap_set_bit (gen, index);
3082 bitmap_clear_bit (kill, index);
3085 store_info = store_info->next;
3090 /* Process the READ_INFOs into the bitmaps into GEN and KILL. KILL
3094 scan_reads_nospill (insn_info_t insn_info, bitmap gen, bitmap kill)
3096 read_info_t read_info = insn_info->read_rec;
3100 /* If this insn reads the frame, kill all the frame related stores. */
3101 if (insn_info->frame_read)
3103 FOR_EACH_VEC_ELT (group_info_t, rtx_group_vec, i, group)
3104 if (group->process_globally && group->frame_related)
3107 bitmap_ior_into (kill, group->group_kill);
3108 bitmap_and_compl_into (gen, group->group_kill);
3111 if (insn_info->non_frame_wild_read)
3113 /* Kill all non-frame related stores. Kill all stores of variables that
3116 bitmap_ior_into (kill, kill_on_calls);
3117 bitmap_and_compl_into (gen, kill_on_calls);
3118 FOR_EACH_VEC_ELT (group_info_t, rtx_group_vec, i, group)
3119 if (group->process_globally && !group->frame_related)
3122 bitmap_ior_into (kill, group->group_kill);
3123 bitmap_and_compl_into (gen, group->group_kill);
3128 FOR_EACH_VEC_ELT (group_info_t, rtx_group_vec, i, group)
3130 if (group->process_globally)
3132 if (i == read_info->group_id)
3134 if (read_info->begin > read_info->end)
3136 /* Begin > end for block mode reads. */
3138 bitmap_ior_into (kill, group->group_kill);
3139 bitmap_and_compl_into (gen, group->group_kill);
3143 /* The groups are the same, just process the
3146 for (j = read_info->begin; j < read_info->end; j++)
3148 int index = get_bitmap_index (group, j);
3152 bitmap_set_bit (kill, index);
3153 bitmap_clear_bit (gen, index);
3160 /* The groups are different, if the alias sets
3161 conflict, clear the entire group. We only need
3162 to apply this test if the read_info is a cselib
3163 read. Anything with a constant base cannot alias
3164 something else with a different constant
3166 if ((read_info->group_id < 0)
3167 && canon_true_dependence (group->base_mem,
3168 GET_MODE (group->base_mem),
3169 group->canon_base_addr,
3170 read_info->mem, NULL_RTX,
3174 bitmap_ior_into (kill, group->group_kill);
3175 bitmap_and_compl_into (gen, group->group_kill);
3181 read_info = read_info->next;
3185 /* Process the READ_INFOs into the bitmaps into GEN and KILL. KILL
3189 scan_reads_spill (read_info_t read_info, bitmap gen, bitmap kill)
3193 if (read_info->alias_set)
3195 int index = get_bitmap_index (clear_alias_group,
3196 read_info->alias_set);
3200 bitmap_set_bit (kill, index);
3201 bitmap_clear_bit (gen, index);
3205 read_info = read_info->next;
3210 /* Return the insn in BB_INFO before the first wild read or if there
3211 are no wild reads in the block, return the last insn. */
3214 find_insn_before_first_wild_read (bb_info_t bb_info)
3216 insn_info_t insn_info = bb_info->last_insn;
3217 insn_info_t last_wild_read = NULL;
3221 if (insn_info->wild_read)
3223 last_wild_read = insn_info->prev_insn;
3224 /* Block starts with wild read. */
3225 if (!last_wild_read)
3229 insn_info = insn_info->prev_insn;
3233 return last_wild_read;
3235 return bb_info->last_insn;
3239 /* Scan the insns in BB_INFO starting at PTR and going to the top of
3240 the block in order to build the gen and kill sets for the block.
3241 We start at ptr which may be the last insn in the block or may be
3242 the first insn with a wild read. In the latter case we are able to
3243 skip the rest of the block because it just does not matter:
3244 anything that happens is hidden by the wild read. */
3247 dse_step3_scan (bool for_spills, basic_block bb)
3249 bb_info_t bb_info = bb_table[bb->index];
3250 insn_info_t insn_info;
3253 /* There are no wild reads in the spill case. */
3254 insn_info = bb_info->last_insn;
3256 insn_info = find_insn_before_first_wild_read (bb_info);
3258 /* In the spill case or in the no_spill case if there is no wild
3259 read in the block, we will need a kill set. */
3260 if (insn_info == bb_info->last_insn)
3263 bitmap_clear (bb_info->kill);
3265 bb_info->kill = BITMAP_ALLOC (NULL);
3269 BITMAP_FREE (bb_info->kill);
3273 /* There may have been code deleted by the dce pass run before
3275 if (insn_info->insn && INSN_P (insn_info->insn))
3277 /* Process the read(s) last. */
3280 scan_stores_spill (insn_info->store_rec, bb_info->gen, bb_info->kill);
3281 scan_reads_spill (insn_info->read_rec, bb_info->gen, bb_info->kill);
3285 scan_stores_nospill (insn_info->store_rec, bb_info->gen, bb_info->kill);
3286 scan_reads_nospill (insn_info, bb_info->gen, bb_info->kill);
3290 insn_info = insn_info->prev_insn;
3295 /* Set the gen set of the exit block, and also any block with no
3296 successors that does not have a wild read. */
3299 dse_step3_exit_block_scan (bb_info_t bb_info)
3301 /* The gen set is all 0's for the exit block except for the
3302 frame_pointer_group. */
3304 if (stores_off_frame_dead_at_return)
3309 FOR_EACH_VEC_ELT (group_info_t, rtx_group_vec, i, group)
3311 if (group->process_globally && group->frame_related)
3312 bitmap_ior_into (bb_info->gen, group->group_kill);
3318 /* Find all of the blocks that are not backwards reachable from the
3319 exit block or any block with no successors (BB). These are the
3320 infinite loops or infinite self loops. These blocks will still
3321 have their bits set in UNREACHABLE_BLOCKS. */
3324 mark_reachable_blocks (sbitmap unreachable_blocks, basic_block bb)
3329 if (TEST_BIT (unreachable_blocks, bb->index))
3331 RESET_BIT (unreachable_blocks, bb->index);
3332 FOR_EACH_EDGE (e, ei, bb->preds)
3334 mark_reachable_blocks (unreachable_blocks, e->src);
3339 /* Build the transfer functions for the function. */
3342 dse_step3 (bool for_spills)
3345 sbitmap unreachable_blocks = sbitmap_alloc (last_basic_block);
3346 sbitmap_iterator sbi;
3347 bitmap all_ones = NULL;
3350 sbitmap_ones (unreachable_blocks);
3354 bb_info_t bb_info = bb_table[bb->index];
3356 bitmap_clear (bb_info->gen);
3358 bb_info->gen = BITMAP_ALLOC (NULL);
3360 if (bb->index == ENTRY_BLOCK)
3362 else if (bb->index == EXIT_BLOCK)
3363 dse_step3_exit_block_scan (bb_info);
3365 dse_step3_scan (for_spills, bb);
3366 if (EDGE_COUNT (bb->succs) == 0)
3367 mark_reachable_blocks (unreachable_blocks, bb);
3369 /* If this is the second time dataflow is run, delete the old
3372 BITMAP_FREE (bb_info->in);
3374 BITMAP_FREE (bb_info->out);
3377 /* For any block in an infinite loop, we must initialize the out set
3378 to all ones. This could be expensive, but almost never occurs in
3379 practice. However, it is common in regression tests. */
3380 EXECUTE_IF_SET_IN_SBITMAP (unreachable_blocks, 0, i, sbi)
3382 if (bitmap_bit_p (all_blocks, i))
3384 bb_info_t bb_info = bb_table[i];
3390 all_ones = BITMAP_ALLOC (NULL);
3391 FOR_EACH_VEC_ELT (group_info_t, rtx_group_vec, j, group)
3392 bitmap_ior_into (all_ones, group->group_kill);
3396 bb_info->out = BITMAP_ALLOC (NULL);
3397 bitmap_copy (bb_info->out, all_ones);
3403 BITMAP_FREE (all_ones);
3404 sbitmap_free (unreachable_blocks);
3409 /*----------------------------------------------------------------------------
3412 Solve the bitvector equations.
3413 ----------------------------------------------------------------------------*/
3416 /* Confluence function for blocks with no successors. Create an out
3417 set from the gen set of the exit block. This block logically has
3418 the exit block as a successor. */
3423 dse_confluence_0 (basic_block bb)
3425 bb_info_t bb_info = bb_table[bb->index];
3427 if (bb->index == EXIT_BLOCK)
3432 bb_info->out = BITMAP_ALLOC (NULL);
3433 bitmap_copy (bb_info->out, bb_table[EXIT_BLOCK]->gen);
3437 /* Propagate the information from the in set of the dest of E to the
3438 out set of the src of E. If the various in or out sets are not
3439 there, that means they are all ones. */
3442 dse_confluence_n (edge e)
3444 bb_info_t src_info = bb_table[e->src->index];
3445 bb_info_t dest_info = bb_table[e->dest->index];
3450 bitmap_and_into (src_info->out, dest_info->in);
3453 src_info->out = BITMAP_ALLOC (NULL);
3454 bitmap_copy (src_info->out, dest_info->in);
3461 /* Propagate the info from the out to the in set of BB_INDEX's basic
3462 block. There are three cases:
3464 1) The block has no kill set. In this case the kill set is all
3465 ones. It does not matter what the out set of the block is, none of
3466 the info can reach the top. The only thing that reaches the top is
3467 the gen set and we just copy the set.
3469 2) There is a kill set but no out set and bb has successors. In
3470 this case we just return. Eventually an out set will be created and
3471 it is better to wait than to create a set of ones.
3473 3) There is both a kill and out set. We apply the obvious transfer
3478 dse_transfer_function (int bb_index)
3480 bb_info_t bb_info = bb_table[bb_index];
3488 return bitmap_ior_and_compl (bb_info->in, bb_info->gen,
3489 bb_info->out, bb_info->kill);
3492 bb_info->in = BITMAP_ALLOC (NULL);
3493 bitmap_ior_and_compl (bb_info->in, bb_info->gen,
3494 bb_info->out, bb_info->kill);
3504 /* Case 1 above. If there is already an in set, nothing
3510 bb_info->in = BITMAP_ALLOC (NULL);
3511 bitmap_copy (bb_info->in, bb_info->gen);
3517 /* Solve the dataflow equations. */
3522 df_simple_dataflow (DF_BACKWARD, NULL, dse_confluence_0,
3523 dse_confluence_n, dse_transfer_function,
3524 all_blocks, df_get_postorder (DF_BACKWARD),
3525 df_get_n_blocks (DF_BACKWARD));
3530 fprintf (dump_file, "\n\n*** Global dataflow info after analysis.\n");
3533 bb_info_t bb_info = bb_table[bb->index];
3535 df_print_bb_index (bb, dump_file);
3537 bitmap_print (dump_file, bb_info->in, " in: ", "\n");
3539 fprintf (dump_file, " in: *MISSING*\n");
3541 bitmap_print (dump_file, bb_info->gen, " gen: ", "\n");
3543 fprintf (dump_file, " gen: *MISSING*\n");
3545 bitmap_print (dump_file, bb_info->kill, " kill: ", "\n");
3547 fprintf (dump_file, " kill: *MISSING*\n");
3549 bitmap_print (dump_file, bb_info->out, " out: ", "\n");
3551 fprintf (dump_file, " out: *MISSING*\n\n");
3558 /*----------------------------------------------------------------------------
3561 Delete the stores that can only be deleted using the global information.
3562 ----------------------------------------------------------------------------*/
3566 dse_step5_nospill (void)
3571 bb_info_t bb_info = bb_table[bb->index];
3572 insn_info_t insn_info = bb_info->last_insn;
3573 bitmap v = bb_info->out;
3577 bool deleted = false;
3578 if (dump_file && insn_info->insn)
3580 fprintf (dump_file, "starting to process insn %d\n",
3581 INSN_UID (insn_info->insn));
3582 bitmap_print (dump_file, v, " v: ", "\n");
3585 /* There may have been code deleted by the dce pass run before
3588 && INSN_P (insn_info->insn)
3589 && (!insn_info->cannot_delete)
3590 && (!bitmap_empty_p (v)))
3592 store_info_t store_info = insn_info->store_rec;
3594 /* Try to delete the current insn. */
3597 /* Skip the clobbers. */
3598 while (!store_info->is_set)
3599 store_info = store_info->next;
3601 if (store_info->alias_set)
3606 group_info_t group_info
3607 = VEC_index (group_info_t, rtx_group_vec, store_info->group_id);
3609 for (i = store_info->begin; i < store_info->end; i++)
3611 int index = get_bitmap_index (group_info, i);
3614 fprintf (dump_file, "i = %d, index = %d\n", (int)i, index);
3615 if (index == 0 || !bitmap_bit_p (v, index))
3618 fprintf (dump_file, "failing at i = %d\n", (int)i);
3628 check_for_inc_dec (insn_info->insn);
3629 delete_insn (insn_info->insn);
3630 insn_info->insn = NULL;
3635 /* We do want to process the local info if the insn was
3636 deleted. For instance, if the insn did a wild read, we
3637 no longer need to trash the info. */
3639 && INSN_P (insn_info->insn)
3642 scan_stores_nospill (insn_info->store_rec, v, NULL);
3643 if (insn_info->wild_read)
3646 fprintf (dump_file, "wild read\n");
3649 else if (insn_info->read_rec
3650 || insn_info->non_frame_wild_read)
3652 if (dump_file && !insn_info->non_frame_wild_read)
3653 fprintf (dump_file, "regular read\n");
3655 fprintf (dump_file, "non-frame wild read\n");
3656 scan_reads_nospill (insn_info, v, NULL);
3660 insn_info = insn_info->prev_insn;
3667 dse_step5_spill (void)
3672 bb_info_t bb_info = bb_table[bb->index];
3673 insn_info_t insn_info = bb_info->last_insn;
3674 bitmap v = bb_info->out;
3678 bool deleted = false;
3679 /* There may have been code deleted by the dce pass run before
3682 && INSN_P (insn_info->insn)
3683 && (!insn_info->cannot_delete)
3684 && (!bitmap_empty_p (v)))
3686 /* Try to delete the current insn. */
3687 store_info_t store_info = insn_info->store_rec;
3692 if (store_info->alias_set)
3694 int index = get_bitmap_index (clear_alias_group,
3695 store_info->alias_set);
3696 if (index == 0 || !bitmap_bit_p (v, index))
3704 store_info = store_info->next;
3706 if (deleted && dbg_cnt (dse))
3709 fprintf (dump_file, "Spill deleting insn %d\n",
3710 INSN_UID (insn_info->insn));
3711 check_for_inc_dec (insn_info->insn);
3712 delete_insn (insn_info->insn);
3714 insn_info->insn = NULL;
3719 && INSN_P (insn_info->insn)
3722 scan_stores_spill (insn_info->store_rec, v, NULL);
3723 scan_reads_spill (insn_info->read_rec, v, NULL);
3726 insn_info = insn_info->prev_insn;
3733 /*----------------------------------------------------------------------------
3736 Delete stores made redundant by earlier stores (which store the same
3737 value) that couldn't be eliminated.
3738 ----------------------------------------------------------------------------*/
3747 bb_info_t bb_info = bb_table[bb->index];
3748 insn_info_t insn_info = bb_info->last_insn;
3752 /* There may have been code deleted by the dce pass run before
3755 && INSN_P (insn_info->insn)
3756 && !insn_info->cannot_delete)
3758 store_info_t s_info = insn_info->store_rec;
3760 while (s_info && !s_info->is_set)
3761 s_info = s_info->next;
3763 && s_info->redundant_reason
3764 && s_info->redundant_reason->insn
3765 && INSN_P (s_info->redundant_reason->insn))
3767 rtx rinsn = s_info->redundant_reason->insn;
3769 fprintf (dump_file, "Locally deleting insn %d "
3770 "because insn %d stores the "
3771 "same value and couldn't be "
3773 INSN_UID (insn_info->insn),
3775 delete_dead_store_insn (insn_info);
3778 insn_info = insn_info->prev_insn;
3783 /*----------------------------------------------------------------------------
3786 Destroy everything left standing.
3787 ----------------------------------------------------------------------------*/
3790 dse_step7 (bool global_done)
3796 FOR_EACH_VEC_ELT (group_info_t, rtx_group_vec, i, group)
3798 free (group->offset_map_n);
3799 free (group->offset_map_p);
3800 BITMAP_FREE (group->store1_n);
3801 BITMAP_FREE (group->store1_p);
3802 BITMAP_FREE (group->store2_n);
3803 BITMAP_FREE (group->store2_p);
3804 BITMAP_FREE (group->escaped_n);
3805 BITMAP_FREE (group->escaped_p);
3806 BITMAP_FREE (group->group_kill);
3812 bb_info_t bb_info = bb_table[bb->index];
3813 BITMAP_FREE (bb_info->gen);
3815 BITMAP_FREE (bb_info->kill);
3817 BITMAP_FREE (bb_info->in);
3819 BITMAP_FREE (bb_info->out);
3822 if (clear_alias_sets)
3824 BITMAP_FREE (clear_alias_sets);
3825 BITMAP_FREE (disqualified_clear_alias_sets);
3826 free_alloc_pool (clear_alias_mode_pool);
3827 htab_delete (clear_alias_mode_table);
3830 end_alias_analysis ();
3832 htab_delete (rtx_group_table);
3833 VEC_free (group_info_t, heap, rtx_group_vec);
3834 BITMAP_FREE (all_blocks);
3835 BITMAP_FREE (scratch);
3836 BITMAP_FREE (kill_on_calls);
3838 free_alloc_pool (rtx_store_info_pool);
3839 free_alloc_pool (read_info_pool);
3840 free_alloc_pool (insn_info_pool);
3841 free_alloc_pool (bb_info_pool);
3842 free_alloc_pool (rtx_group_info_pool);
3843 free_alloc_pool (deferred_change_pool);
3847 /* -------------------------------------------------------------------------
3849 ------------------------------------------------------------------------- */
3851 /* Callback for running pass_rtl_dse. */
3854 rest_of_handle_dse (void)
3856 bool did_global = false;
3858 df_set_flags (DF_DEFER_INSN_RESCAN);
3860 /* Need the notes since we must track live hardregs in the forwards
3862 df_note_add_problem ();
3868 if (dse_step2_nospill ())
3870 df_set_flags (DF_LR_RUN_DCE);
3874 fprintf (dump_file, "doing global processing\n");
3877 dse_step5_nospill ();
3880 /* For the instance of dse that runs after reload, we make a special
3881 pass to process the spills. These are special in that they are
3882 totally transparent, i.e, there is no aliasing issues that need
3883 to be considered. This means that the wild reads that kill
3884 everything else do not apply here. */
3885 if (clear_alias_sets && dse_step2_spill ())
3889 df_set_flags (DF_LR_RUN_DCE);
3894 fprintf (dump_file, "doing global spill processing\n");
3901 dse_step7 (did_global);
3904 fprintf (dump_file, "dse: local deletions = %d, global deletions = %d, spill deletions = %d\n",
3905 locally_deleted, globally_deleted, spill_deleted);
3912 return gate_dse1 () || gate_dse2 ();
3918 return optimize > 0 && flag_dse
3925 return optimize > 0 && flag_dse
3929 struct rtl_opt_pass pass_rtl_dse1 =
3934 gate_dse1, /* gate */
3935 rest_of_handle_dse, /* execute */
3938 0, /* static_pass_number */
3939 TV_DSE1, /* tv_id */
3940 0, /* properties_required */
3941 0, /* properties_provided */
3942 0, /* properties_destroyed */
3943 0, /* todo_flags_start */
3944 TODO_df_finish | TODO_verify_rtl_sharing |
3945 TODO_ggc_collect /* todo_flags_finish */
3949 struct rtl_opt_pass pass_rtl_dse2 =
3954 gate_dse2, /* gate */
3955 rest_of_handle_dse, /* execute */
3958 0, /* static_pass_number */
3959 TV_DSE2, /* tv_id */
3960 0, /* properties_required */
3961 0, /* properties_provided */
3962 0, /* properties_destroyed */
3963 0, /* todo_flags_start */
3964 TODO_df_finish | TODO_verify_rtl_sharing |
3965 TODO_ggc_collect /* todo_flags_finish */