1 /* Global common subexpression elimination/Partial redundancy elimination
2 and global constant/copy propagation for GNU compiler.
3 Copyright (C) 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 - reordering of memory allocation and freeing to be more space efficient
24 - do rough calc of how many regs are needed in each block, and a rough
25 calc of how many regs are available in each class and use that to
26 throttle back the code in cases where RTX_COST is minimal.
27 - a store to the same address as a load does not kill the load if the
28 source of the store is also the destination of the load. Handling this
29 allows more load motion, particularly out of loops.
30 - ability to realloc sbitmap vectors would allow one initial computation
31 of reg_set_in_block with only subsequent additions, rather than
32 recomputing it for each pass
36 /* References searched while implementing this.
38 Compilers Principles, Techniques and Tools
42 Global Optimization by Suppression of Partial Redundancies
44 communications of the acm, Vol. 22, Num. 2, Feb. 1979
46 A Portable Machine-Independent Global Optimizer - Design and Measurements
48 Stanford Ph.D. thesis, Dec. 1983
50 A Fast Algorithm for Code Movement Optimization
52 SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988
54 A Solution to a Problem with Morel and Renvoise's
55 Global Optimization by Suppression of Partial Redundancies
56 K-H Drechsler, M.P. Stadel
57 ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988
59 Practical Adaptation of the Global Optimization
60 Algorithm of Morel and Renvoise
62 ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991
64 Efficiently Computing Static Single Assignment Form and the Control
66 R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck
67 ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991
70 J. Knoop, O. Ruthing, B. Steffen
71 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
73 What's In a Region? Or Computing Control Dependence Regions in Near-Linear
74 Time for Reducible Flow Control
76 ACM Letters on Programming Languages and Systems,
77 Vol. 2, Num. 1-4, Mar-Dec 1993
79 An Efficient Representation for Sparse Sets
80 Preston Briggs, Linda Torczon
81 ACM Letters on Programming Languages and Systems,
82 Vol. 2, Num. 1-4, Mar-Dec 1993
84 A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion
85 K-H Drechsler, M.P. Stadel
86 ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993
88 Partial Dead Code Elimination
89 J. Knoop, O. Ruthing, B. Steffen
90 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
92 Effective Partial Redundancy Elimination
93 P. Briggs, K.D. Cooper
94 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
96 The Program Structure Tree: Computing Control Regions in Linear Time
97 R. Johnson, D. Pearson, K. Pingali
98 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
100 Optimal Code Motion: Theory and Practice
101 J. Knoop, O. Ruthing, B. Steffen
102 ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994
104 The power of assignment motion
105 J. Knoop, O. Ruthing, B. Steffen
106 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
108 Global code motion / global value numbering
110 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
112 Value Driven Redundancy Elimination
114 Rice University Ph.D. thesis, Apr. 1996
118 Massively Scalar Compiler Project, Rice University, Sep. 1996
120 High Performance Compilers for Parallel Computing
124 Advanced Compiler Design and Implementation
126 Morgan Kaufmann, 1997
128 Building an Optimizing Compiler
132 People wishing to speed up the code here should read:
133 Elimination Algorithms for Data Flow Analysis
134 B.G. Ryder, M.C. Paull
135 ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986
137 How to Analyze Large Programs Efficiently and Informatively
138 D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck
139 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
141 People wishing to do something different can find various possibilities
142 in the above papers and elsewhere.
152 #include "hard-reg-set.h"
155 #include "insn-config.h"
157 #include "basic-block.h"
159 #include "function.h"
165 #define obstack_chunk_alloc gmalloc
166 #define obstack_chunk_free free
168 /* Propagate flow information through back edges and thus enable PRE's
169 moving loop invariant calculations out of loops.
171 Originally this tended to create worse overall code, but several
172 improvements during the development of PRE seem to have made following
173 back edges generally a win.
175 Note much of the loop invariant code motion done here would normally
176 be done by loop.c, which has more heuristics for when to move invariants
177 out of loops. At some point we might need to move some of those
178 heuristics into gcse.c. */
179 #define FOLLOW_BACK_EDGES 1
181 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
182 are a superset of those done by GCSE.
184 We perform the following steps:
186 1) Compute basic block information.
188 2) Compute table of places where registers are set.
190 3) Perform copy/constant propagation.
192 4) Perform global cse.
194 5) Perform another pass of copy/constant propagation.
196 Two passes of copy/constant propagation are done because the first one
197 enables more GCSE and the second one helps to clean up the copies that
198 GCSE creates. This is needed more for PRE than for Classic because Classic
199 GCSE will try to use an existing register containing the common
200 subexpression rather than create a new one. This is harder to do for PRE
201 because of the code motion (which Classic GCSE doesn't do).
203 Expressions we are interested in GCSE-ing are of the form
204 (set (pseudo-reg) (expression)).
205 Function want_to_gcse_p says what these are.
207 PRE handles moving invariant expressions out of loops (by treating them as
208 partially redundant).
210 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
211 assignment) based GVN (global value numbering). L. T. Simpson's paper
212 (Rice University) on value numbering is a useful reference for this.
214 **********************
216 We used to support multiple passes but there are diminishing returns in
217 doing so. The first pass usually makes 90% of the changes that are doable.
218 A second pass can make a few more changes made possible by the first pass.
219 Experiments show any further passes don't make enough changes to justify
222 A study of spec92 using an unlimited number of passes:
223 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
224 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
225 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
227 It was found doing copy propagation between each pass enables further
230 PRE is quite expensive in complicated functions because the DFA can take
231 awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can
232 be modified if one wants to experiment.
234 **********************
236 The steps for PRE are:
238 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
240 2) Perform the data flow analysis for PRE.
242 3) Delete the redundant instructions
244 4) Insert the required copies [if any] that make the partially
245 redundant instructions fully redundant.
247 5) For other reaching expressions, insert an instruction to copy the value
248 to a newly created pseudo that will reach the redundant instruction.
250 The deletion is done first so that when we do insertions we
251 know which pseudo reg to use.
253 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
254 argue it is not. The number of iterations for the algorithm to converge
255 is typically 2-4 so I don't view it as that expensive (relatively speaking).
257 PRE GCSE depends heavily on the second CSE pass to clean up the copies
258 we create. To make an expression reach the place where it's redundant,
259 the result of the expression is copied to a new register, and the redundant
260 expression is deleted by replacing it with this new register. Classic GCSE
261 doesn't have this problem as much as it computes the reaching defs of
262 each register in each block and thus can try to use an existing register.
264 **********************
266 A fair bit of simplicity is created by creating small functions for simple
267 tasks, even when the function is only called in one place. This may
268 measurably slow things down [or may not] by creating more function call
269 overhead than is necessary. The source is laid out so that it's trivial
270 to make the affected functions inline so that one can measure what speed
271 up, if any, can be achieved, and maybe later when things settle things can
274 Help stamp out big monolithic functions! */
276 /* GCSE global vars. */
279 static FILE *gcse_file;
281 /* Note whether or not we should run jump optimization after gcse. We
282 want to do this for two cases.
284 * If we changed any jumps via cprop.
286 * If we added any labels via edge splitting. */
288 static int run_jump_opt_after_gcse;
290 /* Bitmaps are normally not included in debugging dumps.
291 However it's useful to be able to print them from GDB.
292 We could create special functions for this, but it's simpler to
293 just allow passing stderr to the dump_foo fns. Since stderr can
294 be a macro, we store a copy here. */
295 static FILE *debug_stderr;
297 /* An obstack for our working variables. */
298 static struct obstack gcse_obstack;
300 /* Non-zero for each mode that supports (set (reg) (reg)).
301 This is trivially true for integer and floating point values.
302 It may or may not be true for condition codes. */
303 static char can_copy_p[(int) NUM_MACHINE_MODES];
305 /* Non-zero if can_copy_p has been initialized. */
306 static int can_copy_init_p;
308 struct reg_use {rtx reg_rtx; };
310 /* Hash table of expressions. */
314 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
316 /* Index in the available expression bitmaps. */
318 /* Next entry with the same hash. */
319 struct expr *next_same_hash;
320 /* List of anticipatable occurrences in basic blocks in the function.
321 An "anticipatable occurrence" is one that is the first occurrence in the
322 basic block, the operands are not modified in the basic block prior
323 to the occurrence and the output is not used between the start of
324 the block and the occurrence. */
325 struct occr *antic_occr;
326 /* List of available occurrence in basic blocks in the function.
327 An "available occurrence" is one that is the last occurrence in the
328 basic block and the operands are not modified by following statements in
329 the basic block [including this insn]. */
330 struct occr *avail_occr;
331 /* Non-null if the computation is PRE redundant.
332 The value is the newly created pseudo-reg to record a copy of the
333 expression in all the places that reach the redundant copy. */
337 /* Occurrence of an expression.
338 There is one per basic block. If a pattern appears more than once the
339 last appearance is used [or first for anticipatable expressions]. */
343 /* Next occurrence of this expression. */
345 /* The insn that computes the expression. */
347 /* Non-zero if this [anticipatable] occurrence has been deleted. */
349 /* Non-zero if this [available] occurrence has been copied to
351 /* ??? This is mutually exclusive with deleted_p, so they could share
356 /* Expression and copy propagation hash tables.
357 Each hash table is an array of buckets.
358 ??? It is known that if it were an array of entries, structure elements
359 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
360 not clear whether in the final analysis a sufficient amount of memory would
361 be saved as the size of the available expression bitmaps would be larger
362 [one could build a mapping table without holes afterwards though].
363 Someday I'll perform the computation and figure it out. */
365 /* Total size of the expression hash table, in elements. */
366 static unsigned int expr_hash_table_size;
369 This is an array of `expr_hash_table_size' elements. */
370 static struct expr **expr_hash_table;
372 /* Total size of the copy propagation hash table, in elements. */
373 static unsigned int set_hash_table_size;
376 This is an array of `set_hash_table_size' elements. */
377 static struct expr **set_hash_table;
379 /* Mapping of uids to cuids.
380 Only real insns get cuids. */
381 static int *uid_cuid;
383 /* Highest UID in UID_CUID. */
386 /* Get the cuid of an insn. */
387 #ifdef ENABLE_CHECKING
388 #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
390 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
393 /* Number of cuids. */
396 /* Mapping of cuids to insns. */
397 static rtx *cuid_insn;
399 /* Get insn from cuid. */
400 #define CUID_INSN(CUID) (cuid_insn[CUID])
402 /* Maximum register number in function prior to doing gcse + 1.
403 Registers created during this pass have regno >= max_gcse_regno.
404 This is named with "gcse" to not collide with global of same name. */
405 static unsigned int max_gcse_regno;
407 /* Maximum number of cse-able expressions found. */
410 /* Maximum number of assignments for copy propagation found. */
413 /* Table of registers that are modified.
415 For each register, each element is a list of places where the pseudo-reg
418 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
419 requires knowledge of which blocks kill which regs [and thus could use
420 a bitmap instead of the lists `reg_set_table' uses].
422 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
423 num-regs) [however perhaps it may be useful to keep the data as is]. One
424 advantage of recording things this way is that `reg_set_table' is fairly
425 sparse with respect to pseudo regs but for hard regs could be fairly dense
426 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
427 up functions like compute_transp since in the case of pseudo-regs we only
428 need to iterate over the number of times a pseudo-reg is set, not over the
429 number of basic blocks [clearly there is a bit of a slow down in the cases
430 where a pseudo is set more than once in a block, however it is believed
431 that the net effect is to speed things up]. This isn't done for hard-regs
432 because recording call-clobbered hard-regs in `reg_set_table' at each
433 function call can consume a fair bit of memory, and iterating over
434 hard-regs stored this way in compute_transp will be more expensive. */
436 typedef struct reg_set
438 /* The next setting of this register. */
439 struct reg_set *next;
440 /* The insn where it was set. */
444 static reg_set **reg_set_table;
446 /* Size of `reg_set_table'.
447 The table starts out at max_gcse_regno + slop, and is enlarged as
449 static int reg_set_table_size;
451 /* Amount to grow `reg_set_table' by when it's full. */
452 #define REG_SET_TABLE_SLOP 100
454 /* This is a list of expressions which are MEMs and will be used by load
456 Load motion tracks MEMs which aren't killed by
457 anything except itself. (ie, loads and stores to a single location).
458 We can then allow movement of these MEM refs with a little special
459 allowance. (all stores copy the same value to the reaching reg used
460 for the loads). This means all values used to store into memory must have
461 no side effects so we can re-issue the setter value.
462 Store Motion uses this structure as an expression table to track stores
463 which look interesting, and might be moveable towards the exit block. */
467 struct expr * expr; /* Gcse expression reference for LM. */
468 rtx pattern; /* Pattern of this mem. */
469 rtx loads; /* INSN list of loads seen. */
470 rtx stores; /* INSN list of stores seen. */
471 struct ls_expr * next; /* Next in the list. */
472 int invalid; /* Invalid for some reason. */
473 int index; /* If it maps to a bitmap index. */
474 int hash_index; /* Index when in a hash table. */
475 rtx reaching_reg; /* Register to use when re-writing. */
478 /* Head of the list of load/store memory refs. */
479 static struct ls_expr * pre_ldst_mems = NULL;
481 /* Bitmap containing one bit for each register in the program.
482 Used when performing GCSE to track which registers have been set since
483 the start of the basic block. */
484 static sbitmap reg_set_bitmap;
486 /* For each block, a bitmap of registers set in the block.
487 This is used by expr_killed_p and compute_transp.
488 It is computed during hash table computation and not by compute_sets
489 as it includes registers added since the last pass (or between cprop and
490 gcse) and it's currently not easy to realloc sbitmap vectors. */
491 static sbitmap *reg_set_in_block;
493 /* Array, indexed by basic block number for a list of insns which modify
494 memory within that block. */
495 static rtx * modify_mem_list;
497 /* This array parallels modify_mem_list, but is kept canonicalized. */
498 static rtx * canon_modify_mem_list;
499 /* Various variables for statistics gathering. */
501 /* Memory used in a pass.
502 This isn't intended to be absolutely precise. Its intent is only
503 to keep an eye on memory usage. */
504 static int bytes_used;
506 /* GCSE substitutions made. */
507 static int gcse_subst_count;
508 /* Number of copy instructions created. */
509 static int gcse_create_count;
510 /* Number of constants propagated. */
511 static int const_prop_count;
512 /* Number of copys propagated. */
513 static int copy_prop_count;
515 /* These variables are used by classic GCSE.
516 Normally they'd be defined a bit later, but `rd_gen' needs to
517 be declared sooner. */
519 /* Each block has a bitmap of each type.
520 The length of each blocks bitmap is:
522 max_cuid - for reaching definitions
523 n_exprs - for available expressions
525 Thus we view the bitmaps as 2 dimensional arrays. i.e.
526 rd_kill[block_num][cuid_num]
527 ae_kill[block_num][expr_num] */
529 /* For reaching defs */
530 static sbitmap *rd_kill, *rd_gen, *reaching_defs, *rd_out;
532 /* for available exprs */
533 static sbitmap *ae_kill, *ae_gen, *ae_in, *ae_out;
535 /* Objects of this type are passed around by the null-pointer check
537 struct null_pointer_info
539 /* The basic block being processed. */
541 /* The first register to be handled in this pass. */
542 unsigned int min_reg;
543 /* One greater than the last register to be handled in this pass. */
544 unsigned int max_reg;
545 sbitmap *nonnull_local;
546 sbitmap *nonnull_killed;
549 static void compute_can_copy PARAMS ((void));
550 static char *gmalloc PARAMS ((unsigned int));
551 static char *grealloc PARAMS ((char *, unsigned int));
552 static char *gcse_alloc PARAMS ((unsigned long));
553 static void alloc_gcse_mem PARAMS ((rtx));
554 static void free_gcse_mem PARAMS ((void));
555 static void alloc_reg_set_mem PARAMS ((int));
556 static void free_reg_set_mem PARAMS ((void));
557 static int get_bitmap_width PARAMS ((int, int, int));
558 static void record_one_set PARAMS ((int, rtx));
559 static void record_set_info PARAMS ((rtx, rtx, void *));
560 static void compute_sets PARAMS ((rtx));
561 static void hash_scan_insn PARAMS ((rtx, int, int));
562 static void hash_scan_set PARAMS ((rtx, rtx, int));
563 static void hash_scan_clobber PARAMS ((rtx, rtx));
564 static void hash_scan_call PARAMS ((rtx, rtx));
565 static int want_to_gcse_p PARAMS ((rtx));
566 static int oprs_unchanged_p PARAMS ((rtx, rtx, int));
567 static int oprs_anticipatable_p PARAMS ((rtx, rtx));
568 static int oprs_available_p PARAMS ((rtx, rtx));
569 static void insert_expr_in_table PARAMS ((rtx, enum machine_mode, rtx,
571 static void insert_set_in_table PARAMS ((rtx, rtx));
572 static unsigned int hash_expr PARAMS ((rtx, enum machine_mode, int *, int));
573 static unsigned int hash_expr_1 PARAMS ((rtx, enum machine_mode, int *));
574 static unsigned int hash_string_1 PARAMS ((const char *));
575 static unsigned int hash_set PARAMS ((int, int));
576 static int expr_equiv_p PARAMS ((rtx, rtx));
577 static void record_last_reg_set_info PARAMS ((rtx, int));
578 static void record_last_mem_set_info PARAMS ((rtx));
579 static void record_last_set_info PARAMS ((rtx, rtx, void *));
580 static void compute_hash_table PARAMS ((int));
581 static void alloc_set_hash_table PARAMS ((int));
582 static void free_set_hash_table PARAMS ((void));
583 static void compute_set_hash_table PARAMS ((void));
584 static void alloc_expr_hash_table PARAMS ((unsigned int));
585 static void free_expr_hash_table PARAMS ((void));
586 static void compute_expr_hash_table PARAMS ((void));
587 static void dump_hash_table PARAMS ((FILE *, const char *, struct expr **,
589 static struct expr *lookup_expr PARAMS ((rtx));
590 static struct expr *lookup_set PARAMS ((unsigned int, rtx));
591 static struct expr *next_set PARAMS ((unsigned int, struct expr *));
592 static void reset_opr_set_tables PARAMS ((void));
593 static int oprs_not_set_p PARAMS ((rtx, rtx));
594 static void mark_call PARAMS ((rtx));
595 static void mark_set PARAMS ((rtx, rtx));
596 static void mark_clobber PARAMS ((rtx, rtx));
597 static void mark_oprs_set PARAMS ((rtx));
598 static void alloc_cprop_mem PARAMS ((int, int));
599 static void free_cprop_mem PARAMS ((void));
600 static void compute_transp PARAMS ((rtx, int, sbitmap *, int));
601 static void compute_transpout PARAMS ((void));
602 static void compute_local_properties PARAMS ((sbitmap *, sbitmap *, sbitmap *,
604 static void compute_cprop_data PARAMS ((void));
605 static void find_used_regs PARAMS ((rtx *, void *));
606 static int try_replace_reg PARAMS ((rtx, rtx, rtx));
607 static struct expr *find_avail_set PARAMS ((int, rtx));
608 static int cprop_jump PARAMS ((basic_block, rtx, rtx, rtx));
610 static int cprop_cc0_jump PARAMS ((basic_block, rtx, struct reg_use *, rtx));
612 static void mems_conflict_for_gcse_p PARAMS ((rtx, rtx, void *));
613 static int load_killed_in_block_p PARAMS ((basic_block, int, rtx, int));
614 static void canon_list_insert PARAMS ((rtx, rtx, void *));
615 static int cprop_insn PARAMS ((basic_block, rtx, int));
616 static int cprop PARAMS ((int));
617 static int one_cprop_pass PARAMS ((int, int));
618 static void alloc_pre_mem PARAMS ((int, int));
619 static void free_pre_mem PARAMS ((void));
620 static void compute_pre_data PARAMS ((void));
621 static int pre_expr_reaches_here_p PARAMS ((basic_block, struct expr *,
623 static void insert_insn_end_bb PARAMS ((struct expr *, basic_block, int));
624 static void pre_insert_copy_insn PARAMS ((struct expr *, rtx));
625 static void pre_insert_copies PARAMS ((void));
626 static int pre_delete PARAMS ((void));
627 static int pre_gcse PARAMS ((void));
628 static int one_pre_gcse_pass PARAMS ((int));
629 static void add_label_notes PARAMS ((rtx, rtx));
630 static void alloc_code_hoist_mem PARAMS ((int, int));
631 static void free_code_hoist_mem PARAMS ((void));
632 static void compute_code_hoist_vbeinout PARAMS ((void));
633 static void compute_code_hoist_data PARAMS ((void));
634 static int hoist_expr_reaches_here_p PARAMS ((basic_block, int, basic_block,
636 static void hoist_code PARAMS ((void));
637 static int one_code_hoisting_pass PARAMS ((void));
638 static void alloc_rd_mem PARAMS ((int, int));
639 static void free_rd_mem PARAMS ((void));
640 static void handle_rd_kill_set PARAMS ((rtx, int, basic_block));
641 static void compute_kill_rd PARAMS ((void));
642 static void compute_rd PARAMS ((void));
643 static void alloc_avail_expr_mem PARAMS ((int, int));
644 static void free_avail_expr_mem PARAMS ((void));
645 static void compute_ae_gen PARAMS ((void));
646 static int expr_killed_p PARAMS ((rtx, basic_block));
647 static void compute_ae_kill PARAMS ((sbitmap *, sbitmap *));
648 static int expr_reaches_here_p PARAMS ((struct occr *, struct expr *,
650 static rtx computing_insn PARAMS ((struct expr *, rtx));
651 static int def_reaches_here_p PARAMS ((rtx, rtx));
652 static int can_disregard_other_sets PARAMS ((struct reg_set **, rtx, int));
653 static int handle_avail_expr PARAMS ((rtx, struct expr *));
654 static int classic_gcse PARAMS ((void));
655 static int one_classic_gcse_pass PARAMS ((int));
656 static void invalidate_nonnull_info PARAMS ((rtx, rtx, void *));
657 static void delete_null_pointer_checks_1 PARAMS ((varray_type *, unsigned int *,
658 sbitmap *, sbitmap *,
659 struct null_pointer_info *));
660 static rtx process_insert_insn PARAMS ((struct expr *));
661 static int pre_edge_insert PARAMS ((struct edge_list *, struct expr **));
662 static int expr_reaches_here_p_work PARAMS ((struct occr *, struct expr *,
663 basic_block, int, char *));
664 static int pre_expr_reaches_here_p_work PARAMS ((basic_block, struct expr *,
665 basic_block, char *));
666 static struct ls_expr * ldst_entry PARAMS ((rtx));
667 static void free_ldst_entry PARAMS ((struct ls_expr *));
668 static void free_ldst_mems PARAMS ((void));
669 static void print_ldst_list PARAMS ((FILE *));
670 static struct ls_expr * find_rtx_in_ldst PARAMS ((rtx));
671 static int enumerate_ldsts PARAMS ((void));
672 static inline struct ls_expr * first_ls_expr PARAMS ((void));
673 static inline struct ls_expr * next_ls_expr PARAMS ((struct ls_expr *));
674 static int simple_mem PARAMS ((rtx));
675 static void invalidate_any_buried_refs PARAMS ((rtx));
676 static void compute_ld_motion_mems PARAMS ((void));
677 static void trim_ld_motion_mems PARAMS ((void));
678 static void update_ld_motion_stores PARAMS ((struct expr *));
679 static void reg_set_info PARAMS ((rtx, rtx, void *));
680 static int store_ops_ok PARAMS ((rtx, basic_block));
681 static void find_moveable_store PARAMS ((rtx));
682 static int compute_store_table PARAMS ((void));
683 static int load_kills_store PARAMS ((rtx, rtx));
684 static int find_loads PARAMS ((rtx, rtx));
685 static int store_killed_in_insn PARAMS ((rtx, rtx));
686 static int store_killed_after PARAMS ((rtx, rtx, basic_block));
687 static int store_killed_before PARAMS ((rtx, rtx, basic_block));
688 static void build_store_vectors PARAMS ((void));
689 static void insert_insn_start_bb PARAMS ((rtx, basic_block));
690 static int insert_store PARAMS ((struct ls_expr *, edge));
691 static void replace_store_insn PARAMS ((rtx, rtx, basic_block));
692 static void delete_store PARAMS ((struct ls_expr *,
694 static void free_store_memory PARAMS ((void));
695 static void store_motion PARAMS ((void));
697 /* Entry point for global common subexpression elimination.
698 F is the first instruction in the function. */
706 /* Bytes used at start of pass. */
707 int initial_bytes_used;
708 /* Maximum number of bytes used by a pass. */
710 /* Point to release obstack data from for each pass. */
711 char *gcse_obstack_bottom;
713 /* Insertion of instructions on edges can create new basic blocks; we
714 need the original basic block count so that we can properly deallocate
715 arrays sized on the number of basic blocks originally in the cfg. */
717 /* We do not construct an accurate cfg in functions which call
718 setjmp, so just punt to be safe. */
719 if (current_function_calls_setjmp)
722 /* Assume that we do not need to run jump optimizations after gcse. */
723 run_jump_opt_after_gcse = 0;
725 /* For calling dump_foo fns from gdb. */
726 debug_stderr = stderr;
729 /* Identify the basic block information for this function, including
730 successors and predecessors. */
731 max_gcse_regno = max_reg_num ();
734 dump_flow_info (file);
736 orig_bb_count = n_basic_blocks;
737 /* Return if there's nothing to do. */
738 if (n_basic_blocks <= 1)
741 /* Trying to perform global optimizations on flow graphs which have
742 a high connectivity will take a long time and is unlikely to be
745 In normal circumstances a cfg should have about twice as many edges
746 as blocks. But we do not want to punish small functions which have
747 a couple switch statements. So we require a relatively large number
748 of basic blocks and the ratio of edges to blocks to be high. */
749 if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
751 if (warn_disabled_optimization)
752 warning ("GCSE disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
753 n_basic_blocks, n_edges / n_basic_blocks);
757 /* If allocating memory for the cprop bitmap would take up too much
758 storage it's better just to disable the optimization. */
760 * SBITMAP_SET_SIZE (max_gcse_regno)
761 * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
763 if (warn_disabled_optimization)
764 warning ("GCSE disabled: %d basic blocks and %d registers",
765 n_basic_blocks, max_gcse_regno);
770 /* See what modes support reg/reg copy operations. */
771 if (! can_copy_init_p)
777 gcc_obstack_init (&gcse_obstack);
781 init_alias_analysis ();
782 /* Record where pseudo-registers are set. This data is kept accurate
783 during each pass. ??? We could also record hard-reg information here
784 [since it's unchanging], however it is currently done during hash table
787 It may be tempting to compute MEM set information here too, but MEM sets
788 will be subject to code motion one day and thus we need to compute
789 information about memory sets when we build the hash tables. */
791 alloc_reg_set_mem (max_gcse_regno);
795 initial_bytes_used = bytes_used;
797 gcse_obstack_bottom = gcse_alloc (1);
799 while (changed && pass < MAX_GCSE_PASSES)
803 fprintf (file, "GCSE pass %d\n\n", pass + 1);
805 /* Initialize bytes_used to the space for the pred/succ lists,
806 and the reg_set_table data. */
807 bytes_used = initial_bytes_used;
809 /* Each pass may create new registers, so recalculate each time. */
810 max_gcse_regno = max_reg_num ();
814 /* Don't allow constant propagation to modify jumps
816 changed = one_cprop_pass (pass + 1, 0);
819 changed |= one_classic_gcse_pass (pass + 1);
822 changed |= one_pre_gcse_pass (pass + 1);
823 /* We may have just created new basic blocks. Release and
824 recompute various things which are sized on the number of
830 for (i = 0; i < orig_bb_count; i++)
832 if (modify_mem_list[i])
833 free_INSN_LIST_list (modify_mem_list + i);
834 if (canon_modify_mem_list[i])
835 free_INSN_LIST_list (canon_modify_mem_list + i);
838 = (rtx *) gmalloc (n_basic_blocks * sizeof (rtx *));
839 canon_modify_mem_list
840 = (rtx *) gmalloc (n_basic_blocks * sizeof (rtx *));
841 memset ((char *) modify_mem_list, 0, n_basic_blocks * sizeof (rtx *));
842 memset ((char *) canon_modify_mem_list, 0, n_basic_blocks * sizeof (rtx *));
843 orig_bb_count = n_basic_blocks;
846 alloc_reg_set_mem (max_reg_num ());
848 run_jump_opt_after_gcse = 1;
851 if (max_pass_bytes < bytes_used)
852 max_pass_bytes = bytes_used;
854 /* Free up memory, then reallocate for code hoisting. We can
855 not re-use the existing allocated memory because the tables
856 will not have info for the insns or registers created by
857 partial redundancy elimination. */
860 /* It does not make sense to run code hoisting unless we optimizing
861 for code size -- it rarely makes programs faster, and can make
862 them bigger if we did partial redundancy elimination (when optimizing
863 for space, we use a classic gcse algorithm instead of partial
864 redundancy algorithms). */
867 max_gcse_regno = max_reg_num ();
869 changed |= one_code_hoisting_pass ();
872 if (max_pass_bytes < bytes_used)
873 max_pass_bytes = bytes_used;
878 fprintf (file, "\n");
882 obstack_free (&gcse_obstack, gcse_obstack_bottom);
886 /* Do one last pass of copy propagation, including cprop into
887 conditional jumps. */
889 max_gcse_regno = max_reg_num ();
891 /* This time, go ahead and allow cprop to alter jumps. */
892 one_cprop_pass (pass + 1, 1);
897 fprintf (file, "GCSE of %s: %d basic blocks, ",
898 current_function_name, n_basic_blocks);
899 fprintf (file, "%d pass%s, %d bytes\n\n",
900 pass, pass > 1 ? "es" : "", max_pass_bytes);
903 obstack_free (&gcse_obstack, NULL);
905 /* We are finished with alias. */
906 end_alias_analysis ();
907 allocate_reg_info (max_reg_num (), FALSE, FALSE);
909 if (!optimize_size && flag_gcse_sm)
911 /* Record where pseudo-registers are set. */
912 return run_jump_opt_after_gcse;
915 /* Misc. utilities. */
917 /* Compute which modes support reg/reg copy operations. */
923 #ifndef AVOID_CCMODE_COPIES
926 memset (can_copy_p, 0, NUM_MACHINE_MODES);
929 for (i = 0; i < NUM_MACHINE_MODES; i++)
930 if (GET_MODE_CLASS (i) == MODE_CC)
932 #ifdef AVOID_CCMODE_COPIES
935 reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1);
936 insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
937 if (recog (PATTERN (insn), insn, NULL) >= 0)
947 /* Cover function to xmalloc to record bytes allocated. */
954 return xmalloc (size);
957 /* Cover function to xrealloc.
958 We don't record the additional size since we don't know it.
959 It won't affect memory usage stats much anyway. */
966 return xrealloc (ptr, size);
969 /* Cover function to obstack_alloc.
970 We don't need to record the bytes allocated here since
971 obstack_chunk_alloc is set to gmalloc. */
977 return (char *) obstack_alloc (&gcse_obstack, size);
980 /* Allocate memory for the cuid mapping array,
981 and reg/memory set tracking tables.
983 This is called at the start of each pass. */
992 /* Find the largest UID and create a mapping from UIDs to CUIDs.
993 CUIDs are like UIDs except they increase monotonically, have no gaps,
994 and only apply to real insns. */
996 max_uid = get_max_uid ();
997 n = (max_uid + 1) * sizeof (int);
998 uid_cuid = (int *) gmalloc (n);
999 memset ((char *) uid_cuid, 0, n);
1000 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
1003 uid_cuid[INSN_UID (insn)] = i++;
1005 uid_cuid[INSN_UID (insn)] = i;
1008 /* Create a table mapping cuids to insns. */
1011 n = (max_cuid + 1) * sizeof (rtx);
1012 cuid_insn = (rtx *) gmalloc (n);
1013 memset ((char *) cuid_insn, 0, n);
1014 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
1016 CUID_INSN (i++) = insn;
1018 /* Allocate vars to track sets of regs. */
1019 reg_set_bitmap = (sbitmap) sbitmap_alloc (max_gcse_regno);
1021 /* Allocate vars to track sets of regs, memory per block. */
1022 reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks,
1024 /* Allocate array to keep a list of insns which modify memory in each
1026 modify_mem_list = (rtx *) gmalloc (n_basic_blocks * sizeof (rtx *));
1027 canon_modify_mem_list = (rtx *) gmalloc (n_basic_blocks * sizeof (rtx *));
1028 memset ((char *) modify_mem_list, 0, n_basic_blocks * sizeof (rtx *));
1029 memset ((char *) canon_modify_mem_list, 0, n_basic_blocks * sizeof (rtx *));
1032 /* Free memory allocated by alloc_gcse_mem. */
1040 free (reg_set_bitmap);
1042 sbitmap_vector_free (reg_set_in_block);
1043 /* re-Cache any INSN_LIST nodes we have allocated. */
1047 for (i = 0; i < n_basic_blocks; i++)
1049 if (modify_mem_list[i])
1050 free_INSN_LIST_list (modify_mem_list + i);
1051 if (canon_modify_mem_list[i])
1052 free_INSN_LIST_list (canon_modify_mem_list + i);
1055 free (modify_mem_list);
1056 free (canon_modify_mem_list);
1057 modify_mem_list = 0;
1058 canon_modify_mem_list = 0;
1062 /* Many of the global optimization algorithms work by solving dataflow
1063 equations for various expressions. Initially, some local value is
1064 computed for each expression in each block. Then, the values across the
1065 various blocks are combined (by following flow graph edges) to arrive at
1066 global values. Conceptually, each set of equations is independent. We
1067 may therefore solve all the equations in parallel, solve them one at a
1068 time, or pick any intermediate approach.
1070 When you're going to need N two-dimensional bitmaps, each X (say, the
1071 number of blocks) by Y (say, the number of expressions), call this
1072 function. It's not important what X and Y represent; only that Y
1073 correspond to the things that can be done in parallel. This function will
1074 return an appropriate chunking factor C; you should solve C sets of
1075 equations in parallel. By going through this function, we can easily
1076 trade space against time; by solving fewer equations in parallel we use
1080 get_bitmap_width (n, x, y)
1085 /* It's not really worth figuring out *exactly* how much memory will
1086 be used by a particular choice. The important thing is to get
1087 something approximately right. */
1088 size_t max_bitmap_memory = 10 * 1024 * 1024;
1090 /* The number of bytes we'd use for a single column of minimum
1092 size_t column_size = n * x * sizeof (SBITMAP_ELT_TYPE);
1094 /* Often, it's reasonable just to solve all the equations in
1096 if (column_size * SBITMAP_SET_SIZE (y) <= max_bitmap_memory)
1099 /* Otherwise, pick the largest width we can, without going over the
1101 return SBITMAP_ELT_BITS * ((max_bitmap_memory + column_size - 1)
1105 /* Compute the local properties of each recorded expression.
1107 Local properties are those that are defined by the block, irrespective of
1110 An expression is transparent in a block if its operands are not modified
1113 An expression is computed (locally available) in a block if it is computed
1114 at least once and expression would contain the same value if the
1115 computation was moved to the end of the block.
1117 An expression is locally anticipatable in a block if it is computed at
1118 least once and expression would contain the same value if the computation
1119 was moved to the beginning of the block.
1121 We call this routine for cprop, pre and code hoisting. They all compute
1122 basically the same information and thus can easily share this code.
1124 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1125 properties. If NULL, then it is not necessary to compute or record that
1126 particular property.
1128 SETP controls which hash table to look at. If zero, this routine looks at
1129 the expr hash table; if nonzero this routine looks at the set hash table.
1130 Additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1134 compute_local_properties (transp, comp, antloc, setp)
1140 unsigned int i, hash_table_size;
1141 struct expr **hash_table;
1143 /* Initialize any bitmaps that were passed in. */
1147 sbitmap_vector_zero (transp, n_basic_blocks);
1149 sbitmap_vector_ones (transp, n_basic_blocks);
1153 sbitmap_vector_zero (comp, n_basic_blocks);
1155 sbitmap_vector_zero (antloc, n_basic_blocks);
1157 /* We use the same code for cprop, pre and hoisting. For cprop
1158 we care about the set hash table, for pre and hoisting we
1159 care about the expr hash table. */
1160 hash_table_size = setp ? set_hash_table_size : expr_hash_table_size;
1161 hash_table = setp ? set_hash_table : expr_hash_table;
1163 for (i = 0; i < hash_table_size; i++)
1167 for (expr = hash_table[i]; expr != NULL; expr = expr->next_same_hash)
1169 int indx = expr->bitmap_index;
1172 /* The expression is transparent in this block if it is not killed.
1173 We start by assuming all are transparent [none are killed], and
1174 then reset the bits for those that are. */
1176 compute_transp (expr->expr, indx, transp, setp);
1178 /* The occurrences recorded in antic_occr are exactly those that
1179 we want to set to non-zero in ANTLOC. */
1181 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
1183 SET_BIT (antloc[BLOCK_NUM (occr->insn)], indx);
1185 /* While we're scanning the table, this is a good place to
1187 occr->deleted_p = 0;
1190 /* The occurrences recorded in avail_occr are exactly those that
1191 we want to set to non-zero in COMP. */
1193 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
1195 SET_BIT (comp[BLOCK_NUM (occr->insn)], indx);
1197 /* While we're scanning the table, this is a good place to
1202 /* While we're scanning the table, this is a good place to
1204 expr->reaching_reg = 0;
1209 /* Register set information.
1211 `reg_set_table' records where each register is set or otherwise
1214 static struct obstack reg_set_obstack;
1217 alloc_reg_set_mem (n_regs)
1222 reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
1223 n = reg_set_table_size * sizeof (struct reg_set *);
1224 reg_set_table = (struct reg_set **) gmalloc (n);
1225 memset ((char *) reg_set_table, 0, n);
1227 gcc_obstack_init (®_set_obstack);
1233 free (reg_set_table);
1234 obstack_free (®_set_obstack, NULL);
1237 /* Record REGNO in the reg_set table. */
1240 record_one_set (regno, insn)
1244 /* Allocate a new reg_set element and link it onto the list. */
1245 struct reg_set *new_reg_info;
1247 /* If the table isn't big enough, enlarge it. */
1248 if (regno >= reg_set_table_size)
1250 int new_size = regno + REG_SET_TABLE_SLOP;
1253 = (struct reg_set **) grealloc ((char *) reg_set_table,
1254 new_size * sizeof (struct reg_set *));
1255 memset ((char *) (reg_set_table + reg_set_table_size), 0,
1256 (new_size - reg_set_table_size) * sizeof (struct reg_set *));
1257 reg_set_table_size = new_size;
1260 new_reg_info = (struct reg_set *) obstack_alloc (®_set_obstack,
1261 sizeof (struct reg_set));
1262 bytes_used += sizeof (struct reg_set);
1263 new_reg_info->insn = insn;
1264 new_reg_info->next = reg_set_table[regno];
1265 reg_set_table[regno] = new_reg_info;
1268 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1269 an insn. The DATA is really the instruction in which the SET is
1273 record_set_info (dest, setter, data)
1274 rtx dest, setter ATTRIBUTE_UNUSED;
1277 rtx record_set_insn = (rtx) data;
1279 if (GET_CODE (dest) == REG && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
1280 record_one_set (REGNO (dest), record_set_insn);
1283 /* Scan the function and record each set of each pseudo-register.
1285 This is called once, at the start of the gcse pass. See the comments for
1286 `reg_set_table' for further documenation. */
1294 for (insn = f; insn != 0; insn = NEXT_INSN (insn))
1296 note_stores (PATTERN (insn), record_set_info, insn);
1299 /* Hash table support. */
1301 /* For each register, the cuid of the first/last insn in the block
1302 that set it, or -1 if not set. */
1303 #define NEVER_SET -1
1305 struct reg_avail_info
1312 static struct reg_avail_info *reg_avail_info;
1313 static int current_bb;
1316 /* See whether X, the source of a set, is something we want to consider for
1323 static rtx test_insn = 0;
1324 int num_clobbers = 0;
1327 switch (GET_CODE (x))
1340 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1341 if (general_operand (x, GET_MODE (x)))
1343 else if (GET_MODE (x) == VOIDmode)
1346 /* Otherwise, check if we can make a valid insn from it. First initialize
1347 our test insn if we haven't already. */
1351 = make_insn_raw (gen_rtx_SET (VOIDmode,
1352 gen_rtx_REG (word_mode,
1353 FIRST_PSEUDO_REGISTER * 2),
1355 NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0;
1356 ggc_add_rtx_root (&test_insn, 1);
1359 /* Now make an insn like the one we would make when GCSE'ing and see if
1361 PUT_MODE (SET_DEST (PATTERN (test_insn)), GET_MODE (x));
1362 SET_SRC (PATTERN (test_insn)) = x;
1363 return ((icode = recog (PATTERN (test_insn), test_insn, &num_clobbers)) >= 0
1364 && (num_clobbers == 0 || ! added_clobbers_hard_reg_p (icode)));
1367 /* Return non-zero if the operands of expression X are unchanged from the
1368 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1369 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1372 oprs_unchanged_p (x, insn, avail_p)
1383 code = GET_CODE (x);
1388 struct reg_avail_info *info = ®_avail_info[REGNO (x)];
1390 if (info->last_bb != current_bb)
1393 return info->last_set < INSN_CUID (insn);
1395 return info->first_set >= INSN_CUID (insn);
1399 if (load_killed_in_block_p (BASIC_BLOCK (current_bb), INSN_CUID (insn),
1403 return oprs_unchanged_p (XEXP (x, 0), insn, avail_p);
1428 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1432 /* If we are about to do the last recursive call needed at this
1433 level, change it into iteration. This function is called enough
1436 return oprs_unchanged_p (XEXP (x, i), insn, avail_p);
1438 else if (! oprs_unchanged_p (XEXP (x, i), insn, avail_p))
1441 else if (fmt[i] == 'E')
1442 for (j = 0; j < XVECLEN (x, i); j++)
1443 if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p))
1450 /* Used for communication between mems_conflict_for_gcse_p and
1451 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1452 conflict between two memory references. */
1453 static int gcse_mems_conflict_p;
1455 /* Used for communication between mems_conflict_for_gcse_p and
1456 load_killed_in_block_p. A memory reference for a load instruction,
1457 mems_conflict_for_gcse_p will see if a memory store conflicts with
1458 this memory load. */
1459 static rtx gcse_mem_operand;
1461 /* DEST is the output of an instruction. If it is a memory reference, and
1462 possibly conflicts with the load found in gcse_mem_operand, then set
1463 gcse_mems_conflict_p to a nonzero value. */
1466 mems_conflict_for_gcse_p (dest, setter, data)
1467 rtx dest, setter ATTRIBUTE_UNUSED;
1468 void *data ATTRIBUTE_UNUSED;
1470 while (GET_CODE (dest) == SUBREG
1471 || GET_CODE (dest) == ZERO_EXTRACT
1472 || GET_CODE (dest) == SIGN_EXTRACT
1473 || GET_CODE (dest) == STRICT_LOW_PART)
1474 dest = XEXP (dest, 0);
1476 /* If DEST is not a MEM, then it will not conflict with the load. Note
1477 that function calls are assumed to clobber memory, but are handled
1479 if (GET_CODE (dest) != MEM)
1482 /* If we are setting a MEM in our list of specially recognized MEMs,
1483 don't mark as killed this time. */
1485 if (dest == gcse_mem_operand && pre_ldst_mems != NULL)
1487 if (!find_rtx_in_ldst (dest))
1488 gcse_mems_conflict_p = 1;
1492 if (true_dependence (dest, GET_MODE (dest), gcse_mem_operand,
1494 gcse_mems_conflict_p = 1;
1497 /* Return nonzero if the expression in X (a memory reference) is killed
1498 in block BB before or after the insn with the CUID in UID_LIMIT.
1499 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1502 To check the entire block, set UID_LIMIT to max_uid + 1 and
1506 load_killed_in_block_p (bb, uid_limit, x, avail_p)
1512 rtx list_entry = modify_mem_list[bb->index];
1516 /* Ignore entries in the list that do not apply. */
1518 && INSN_CUID (XEXP (list_entry, 0)) < uid_limit)
1520 && INSN_CUID (XEXP (list_entry, 0)) > uid_limit))
1522 list_entry = XEXP (list_entry, 1);
1526 setter = XEXP (list_entry, 0);
1528 /* If SETTER is a call everything is clobbered. Note that calls
1529 to pure functions are never put on the list, so we need not
1530 worry about them. */
1531 if (GET_CODE (setter) == CALL_INSN)
1534 /* SETTER must be an INSN of some kind that sets memory. Call
1535 note_stores to examine each hunk of memory that is modified.
1537 The note_stores interface is pretty limited, so we have to
1538 communicate via global variables. Yuk. */
1539 gcse_mem_operand = x;
1540 gcse_mems_conflict_p = 0;
1541 note_stores (PATTERN (setter), mems_conflict_for_gcse_p, NULL);
1542 if (gcse_mems_conflict_p)
1544 list_entry = XEXP (list_entry, 1);
1549 /* Return non-zero if the operands of expression X are unchanged from
1550 the start of INSN's basic block up to but not including INSN. */
1553 oprs_anticipatable_p (x, insn)
1556 return oprs_unchanged_p (x, insn, 0);
1559 /* Return non-zero if the operands of expression X are unchanged from
1560 INSN to the end of INSN's basic block. */
1563 oprs_available_p (x, insn)
1566 return oprs_unchanged_p (x, insn, 1);
1569 /* Hash expression X.
1571 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1572 indicating if a volatile operand is found or if the expression contains
1573 something we don't want to insert in the table.
1575 ??? One might want to merge this with canon_hash. Later. */
1578 hash_expr (x, mode, do_not_record_p, hash_table_size)
1580 enum machine_mode mode;
1581 int *do_not_record_p;
1582 int hash_table_size;
1586 *do_not_record_p = 0;
1588 hash = hash_expr_1 (x, mode, do_not_record_p);
1589 return hash % hash_table_size;
1592 /* Hash a string. Just add its bytes up. */
1594 static inline unsigned
1599 const unsigned char *p = (const unsigned char *)ps;
1608 /* Subroutine of hash_expr to do the actual work. */
1611 hash_expr_1 (x, mode, do_not_record_p)
1613 enum machine_mode mode;
1614 int *do_not_record_p;
1621 /* Used to turn recursion into iteration. We can't rely on GCC's
1622 tail-recursion eliminatio since we need to keep accumulating values
1629 code = GET_CODE (x);
1633 hash += ((unsigned int) REG << 7) + REGNO (x);
1637 hash += (((unsigned int) CONST_INT << 7) + (unsigned int) mode
1638 + (unsigned int) INTVAL (x));
1642 /* This is like the general case, except that it only counts
1643 the integers representing the constant. */
1644 hash += (unsigned int) code + (unsigned int) GET_MODE (x);
1645 if (GET_MODE (x) != VOIDmode)
1646 for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++)
1647 hash += (unsigned int) XWINT (x, i);
1649 hash += ((unsigned int) CONST_DOUBLE_LOW (x)
1650 + (unsigned int) CONST_DOUBLE_HIGH (x));
1653 /* Assume there is only one rtx object for any given label. */
1655 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1656 differences and differences between each stage's debugging dumps. */
1657 hash += (((unsigned int) LABEL_REF << 7)
1658 + CODE_LABEL_NUMBER (XEXP (x, 0)));
1663 /* Don't hash on the symbol's address to avoid bootstrap differences.
1664 Different hash values may cause expressions to be recorded in
1665 different orders and thus different registers to be used in the
1666 final assembler. This also avoids differences in the dump files
1667 between various stages. */
1669 const unsigned char *p = (const unsigned char *) XSTR (x, 0);
1672 h += (h << 7) + *p++; /* ??? revisit */
1674 hash += ((unsigned int) SYMBOL_REF << 7) + h;
1679 if (MEM_VOLATILE_P (x))
1681 *do_not_record_p = 1;
1685 hash += (unsigned int) MEM;
1686 hash += MEM_ALIAS_SET (x);
1697 case UNSPEC_VOLATILE:
1698 *do_not_record_p = 1;
1702 if (MEM_VOLATILE_P (x))
1704 *do_not_record_p = 1;
1709 /* We don't want to take the filename and line into account. */
1710 hash += (unsigned) code + (unsigned) GET_MODE (x)
1711 + hash_string_1 (ASM_OPERANDS_TEMPLATE (x))
1712 + hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x))
1713 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x);
1715 if (ASM_OPERANDS_INPUT_LENGTH (x))
1717 for (i = 1; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
1719 hash += (hash_expr_1 (ASM_OPERANDS_INPUT (x, i),
1720 GET_MODE (ASM_OPERANDS_INPUT (x, i)),
1722 + hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT
1726 hash += hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x, 0));
1727 x = ASM_OPERANDS_INPUT (x, 0);
1728 mode = GET_MODE (x);
1738 hash += (unsigned) code + (unsigned) GET_MODE (x);
1739 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1743 /* If we are about to do the last recursive call
1744 needed at this level, change it into iteration.
1745 This function is called enough to be worth it. */
1752 hash += hash_expr_1 (XEXP (x, i), 0, do_not_record_p);
1753 if (*do_not_record_p)
1757 else if (fmt[i] == 'E')
1758 for (j = 0; j < XVECLEN (x, i); j++)
1760 hash += hash_expr_1 (XVECEXP (x, i, j), 0, do_not_record_p);
1761 if (*do_not_record_p)
1765 else if (fmt[i] == 's')
1766 hash += hash_string_1 (XSTR (x, i));
1767 else if (fmt[i] == 'i')
1768 hash += (unsigned int) XINT (x, i);
1776 /* Hash a set of register REGNO.
1778 Sets are hashed on the register that is set. This simplifies the PRE copy
1781 ??? May need to make things more elaborate. Later, as necessary. */
1784 hash_set (regno, hash_table_size)
1786 int hash_table_size;
1791 return hash % hash_table_size;
1794 /* Return non-zero if exp1 is equivalent to exp2.
1795 ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
1802 register enum rtx_code code;
1803 register const char *fmt;
1808 if (x == 0 || y == 0)
1811 code = GET_CODE (x);
1812 if (code != GET_CODE (y))
1815 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
1816 if (GET_MODE (x) != GET_MODE (y))
1826 return INTVAL (x) == INTVAL (y);
1829 return XEXP (x, 0) == XEXP (y, 0);
1832 return XSTR (x, 0) == XSTR (y, 0);
1835 return REGNO (x) == REGNO (y);
1838 /* Can't merge two expressions in different alias sets, since we can
1839 decide that the expression is transparent in a block when it isn't,
1840 due to it being set with the different alias set. */
1841 if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
1845 /* For commutative operations, check both orders. */
1853 return ((expr_equiv_p (XEXP (x, 0), XEXP (y, 0))
1854 && expr_equiv_p (XEXP (x, 1), XEXP (y, 1)))
1855 || (expr_equiv_p (XEXP (x, 0), XEXP (y, 1))
1856 && expr_equiv_p (XEXP (x, 1), XEXP (y, 0))));
1859 /* We don't use the generic code below because we want to
1860 disregard filename and line numbers. */
1862 /* A volatile asm isn't equivalent to any other. */
1863 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
1866 if (GET_MODE (x) != GET_MODE (y)
1867 || strcmp (ASM_OPERANDS_TEMPLATE (x), ASM_OPERANDS_TEMPLATE (y))
1868 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x),
1869 ASM_OPERANDS_OUTPUT_CONSTRAINT (y))
1870 || ASM_OPERANDS_OUTPUT_IDX (x) != ASM_OPERANDS_OUTPUT_IDX (y)
1871 || ASM_OPERANDS_INPUT_LENGTH (x) != ASM_OPERANDS_INPUT_LENGTH (y))
1874 if (ASM_OPERANDS_INPUT_LENGTH (x))
1876 for (i = ASM_OPERANDS_INPUT_LENGTH (x) - 1; i >= 0; i--)
1877 if (! expr_equiv_p (ASM_OPERANDS_INPUT (x, i),
1878 ASM_OPERANDS_INPUT (y, i))
1879 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x, i),
1880 ASM_OPERANDS_INPUT_CONSTRAINT (y, i)))
1890 /* Compare the elements. If any pair of corresponding elements
1891 fail to match, return 0 for the whole thing. */
1893 fmt = GET_RTX_FORMAT (code);
1894 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1899 if (! expr_equiv_p (XEXP (x, i), XEXP (y, i)))
1904 if (XVECLEN (x, i) != XVECLEN (y, i))
1906 for (j = 0; j < XVECLEN (x, i); j++)
1907 if (! expr_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
1912 if (strcmp (XSTR (x, i), XSTR (y, i)))
1917 if (XINT (x, i) != XINT (y, i))
1922 if (XWINT (x, i) != XWINT (y, i))
1937 /* Insert expression X in INSN in the hash table.
1938 If it is already present, record it as the last occurrence in INSN's
1941 MODE is the mode of the value X is being stored into.
1942 It is only used if X is a CONST_INT.
1944 ANTIC_P is non-zero if X is an anticipatable expression.
1945 AVAIL_P is non-zero if X is an available expression. */
1948 insert_expr_in_table (x, mode, insn, antic_p, avail_p)
1950 enum machine_mode mode;
1952 int antic_p, avail_p;
1954 int found, do_not_record_p;
1956 struct expr *cur_expr, *last_expr = NULL;
1957 struct occr *antic_occr, *avail_occr;
1958 struct occr *last_occr = NULL;
1960 hash = hash_expr (x, mode, &do_not_record_p, expr_hash_table_size);
1962 /* Do not insert expression in table if it contains volatile operands,
1963 or if hash_expr determines the expression is something we don't want
1964 to or can't handle. */
1965 if (do_not_record_p)
1968 cur_expr = expr_hash_table[hash];
1971 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
1973 /* If the expression isn't found, save a pointer to the end of
1975 last_expr = cur_expr;
1976 cur_expr = cur_expr->next_same_hash;
1981 cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr));
1982 bytes_used += sizeof (struct expr);
1983 if (expr_hash_table[hash] == NULL)
1984 /* This is the first pattern that hashed to this index. */
1985 expr_hash_table[hash] = cur_expr;
1987 /* Add EXPR to end of this hash chain. */
1988 last_expr->next_same_hash = cur_expr;
1990 /* Set the fields of the expr element. */
1992 cur_expr->bitmap_index = n_exprs++;
1993 cur_expr->next_same_hash = NULL;
1994 cur_expr->antic_occr = NULL;
1995 cur_expr->avail_occr = NULL;
1998 /* Now record the occurrence(s). */
2001 antic_occr = cur_expr->antic_occr;
2003 /* Search for another occurrence in the same basic block. */
2004 while (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn))
2006 /* If an occurrence isn't found, save a pointer to the end of
2008 last_occr = antic_occr;
2009 antic_occr = antic_occr->next;
2013 /* Found another instance of the expression in the same basic block.
2014 Prefer the currently recorded one. We want the first one in the
2015 block and the block is scanned from start to end. */
2016 ; /* nothing to do */
2019 /* First occurrence of this expression in this basic block. */
2020 antic_occr = (struct occr *) gcse_alloc (sizeof (struct occr));
2021 bytes_used += sizeof (struct occr);
2022 /* First occurrence of this expression in any block? */
2023 if (cur_expr->antic_occr == NULL)
2024 cur_expr->antic_occr = antic_occr;
2026 last_occr->next = antic_occr;
2028 antic_occr->insn = insn;
2029 antic_occr->next = NULL;
2035 avail_occr = cur_expr->avail_occr;
2037 /* Search for another occurrence in the same basic block. */
2038 while (avail_occr && BLOCK_NUM (avail_occr->insn) != BLOCK_NUM (insn))
2040 /* If an occurrence isn't found, save a pointer to the end of
2042 last_occr = avail_occr;
2043 avail_occr = avail_occr->next;
2047 /* Found another instance of the expression in the same basic block.
2048 Prefer this occurrence to the currently recorded one. We want
2049 the last one in the block and the block is scanned from start
2051 avail_occr->insn = insn;
2054 /* First occurrence of this expression in this basic block. */
2055 avail_occr = (struct occr *) gcse_alloc (sizeof (struct occr));
2056 bytes_used += sizeof (struct occr);
2058 /* First occurrence of this expression in any block? */
2059 if (cur_expr->avail_occr == NULL)
2060 cur_expr->avail_occr = avail_occr;
2062 last_occr->next = avail_occr;
2064 avail_occr->insn = insn;
2065 avail_occr->next = NULL;
2070 /* Insert pattern X in INSN in the hash table.
2071 X is a SET of a reg to either another reg or a constant.
2072 If it is already present, record it as the last occurrence in INSN's
2076 insert_set_in_table (x, insn)
2082 struct expr *cur_expr, *last_expr = NULL;
2083 struct occr *cur_occr, *last_occr = NULL;
2085 if (GET_CODE (x) != SET
2086 || GET_CODE (SET_DEST (x)) != REG)
2089 hash = hash_set (REGNO (SET_DEST (x)), set_hash_table_size);
2091 cur_expr = set_hash_table[hash];
2094 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
2096 /* If the expression isn't found, save a pointer to the end of
2098 last_expr = cur_expr;
2099 cur_expr = cur_expr->next_same_hash;
2104 cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr));
2105 bytes_used += sizeof (struct expr);
2106 if (set_hash_table[hash] == NULL)
2107 /* This is the first pattern that hashed to this index. */
2108 set_hash_table[hash] = cur_expr;
2110 /* Add EXPR to end of this hash chain. */
2111 last_expr->next_same_hash = cur_expr;
2113 /* Set the fields of the expr element.
2114 We must copy X because it can be modified when copy propagation is
2115 performed on its operands. */
2116 cur_expr->expr = copy_rtx (x);
2117 cur_expr->bitmap_index = n_sets++;
2118 cur_expr->next_same_hash = NULL;
2119 cur_expr->antic_occr = NULL;
2120 cur_expr->avail_occr = NULL;
2123 /* Now record the occurrence. */
2124 cur_occr = cur_expr->avail_occr;
2126 /* Search for another occurrence in the same basic block. */
2127 while (cur_occr && BLOCK_NUM (cur_occr->insn) != BLOCK_NUM (insn))
2129 /* If an occurrence isn't found, save a pointer to the end of
2131 last_occr = cur_occr;
2132 cur_occr = cur_occr->next;
2136 /* Found another instance of the expression in the same basic block.
2137 Prefer this occurrence to the currently recorded one. We want the
2138 last one in the block and the block is scanned from start to end. */
2139 cur_occr->insn = insn;
2142 /* First occurrence of this expression in this basic block. */
2143 cur_occr = (struct occr *) gcse_alloc (sizeof (struct occr));
2144 bytes_used += sizeof (struct occr);
2146 /* First occurrence of this expression in any block? */
2147 if (cur_expr->avail_occr == NULL)
2148 cur_expr->avail_occr = cur_occr;
2150 last_occr->next = cur_occr;
2152 cur_occr->insn = insn;
2153 cur_occr->next = NULL;
2157 /* Scan pattern PAT of INSN and add an entry to the hash table. If SET_P is
2158 non-zero, this is for the assignment hash table, otherwise it is for the
2159 expression hash table. */
2162 hash_scan_set (pat, insn, set_p)
2166 rtx src = SET_SRC (pat);
2167 rtx dest = SET_DEST (pat);
2170 if (GET_CODE (src) == CALL)
2171 hash_scan_call (src, insn);
2173 else if (GET_CODE (dest) == REG)
2175 unsigned int regno = REGNO (dest);
2178 /* If this is a single set and we are doing constant propagation,
2179 see if a REG_NOTE shows this equivalent to a constant. */
2180 if (set_p && (note = find_reg_equal_equiv_note (insn)) != 0
2181 && CONSTANT_P (XEXP (note, 0)))
2182 src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src);
2184 /* Only record sets of pseudo-regs in the hash table. */
2186 && regno >= FIRST_PSEUDO_REGISTER
2187 /* Don't GCSE something if we can't do a reg/reg copy. */
2188 && can_copy_p [GET_MODE (dest)]
2189 /* Is SET_SRC something we want to gcse? */
2190 && want_to_gcse_p (src)
2191 /* Don't CSE a nop. */
2192 && ! set_noop_p (pat)
2193 /* Don't GCSE if it has attached REG_EQUIV note.
2194 At this point this only function parameters should have
2195 REG_EQUIV notes and if the argument slot is used somewhere
2196 explicitely, it means address of parameter has been taken,
2197 so we should not extend the lifetime of the pseudo. */
2198 && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
2199 || GET_CODE (XEXP (note, 0)) != MEM))
2201 /* An expression is not anticipatable if its operands are
2202 modified before this insn or if this is not the only SET in
2204 int antic_p = oprs_anticipatable_p (src, insn) && single_set (insn);
2205 /* An expression is not available if its operands are
2206 subsequently modified, including this insn. It's also not
2207 available if this is a branch, because we can't insert
2208 a set after the branch. */
2209 int avail_p = (oprs_available_p (src, insn)
2210 && ! JUMP_P (insn));
2212 insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p);
2215 /* Record sets for constant/copy propagation. */
2217 && regno >= FIRST_PSEUDO_REGISTER
2218 && ((GET_CODE (src) == REG
2219 && REGNO (src) >= FIRST_PSEUDO_REGISTER
2220 && can_copy_p [GET_MODE (dest)]
2221 && REGNO (src) != regno)
2222 || GET_CODE (src) == CONST_INT
2223 || GET_CODE (src) == SYMBOL_REF
2224 || GET_CODE (src) == CONST_DOUBLE)
2225 /* A copy is not available if its src or dest is subsequently
2226 modified. Here we want to search from INSN+1 on, but
2227 oprs_available_p searches from INSN on. */
2228 && (insn == BLOCK_END (BLOCK_NUM (insn))
2229 || ((tmp = next_nonnote_insn (insn)) != NULL_RTX
2230 && oprs_available_p (pat, tmp))))
2231 insert_set_in_table (pat, insn);
2236 hash_scan_clobber (x, insn)
2237 rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED;
2239 /* Currently nothing to do. */
2243 hash_scan_call (x, insn)
2244 rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED;
2246 /* Currently nothing to do. */
2249 /* Process INSN and add hash table entries as appropriate.
2251 Only available expressions that set a single pseudo-reg are recorded.
2253 Single sets in a PARALLEL could be handled, but it's an extra complication
2254 that isn't dealt with right now. The trick is handling the CLOBBERs that
2255 are also in the PARALLEL. Later.
2257 If SET_P is non-zero, this is for the assignment hash table,
2258 otherwise it is for the expression hash table.
2259 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
2260 not record any expressions. */
2263 hash_scan_insn (insn, set_p, in_libcall_block)
2266 int in_libcall_block;
2268 rtx pat = PATTERN (insn);
2271 if (in_libcall_block)
2274 /* Pick out the sets of INSN and for other forms of instructions record
2275 what's been modified. */
2277 if (GET_CODE (pat) == SET)
2278 hash_scan_set (pat, insn, set_p);
2279 else if (GET_CODE (pat) == PARALLEL)
2280 for (i = 0; i < XVECLEN (pat, 0); i++)
2282 rtx x = XVECEXP (pat, 0, i);
2284 if (GET_CODE (x) == SET)
2285 hash_scan_set (x, insn, set_p);
2286 else if (GET_CODE (x) == CLOBBER)
2287 hash_scan_clobber (x, insn);
2288 else if (GET_CODE (x) == CALL)
2289 hash_scan_call (x, insn);
2292 else if (GET_CODE (pat) == CLOBBER)
2293 hash_scan_clobber (pat, insn);
2294 else if (GET_CODE (pat) == CALL)
2295 hash_scan_call (pat, insn);
2299 dump_hash_table (file, name, table, table_size, total_size)
2302 struct expr **table;
2303 int table_size, total_size;
2306 /* Flattened out table, so it's printed in proper order. */
2307 struct expr **flat_table;
2308 unsigned int *hash_val;
2312 = (struct expr **) xcalloc (total_size, sizeof (struct expr *));
2313 hash_val = (unsigned int *) xmalloc (total_size * sizeof (unsigned int));
2315 for (i = 0; i < table_size; i++)
2316 for (expr = table[i]; expr != NULL; expr = expr->next_same_hash)
2318 flat_table[expr->bitmap_index] = expr;
2319 hash_val[expr->bitmap_index] = i;
2322 fprintf (file, "%s hash table (%d buckets, %d entries)\n",
2323 name, table_size, total_size);
2325 for (i = 0; i < total_size; i++)
2326 if (flat_table[i] != 0)
2328 expr = flat_table[i];
2329 fprintf (file, "Index %d (hash value %d)\n ",
2330 expr->bitmap_index, hash_val[i]);
2331 print_rtl (file, expr->expr);
2332 fprintf (file, "\n");
2335 fprintf (file, "\n");
2341 /* Record register first/last/block set information for REGNO in INSN.
2343 first_set records the first place in the block where the register
2344 is set and is used to compute "anticipatability".
2346 last_set records the last place in the block where the register
2347 is set and is used to compute "availability".
2349 last_bb records the block for which first_set and last_set are
2350 valid, as a quick test to invalidate them.
2352 reg_set_in_block records whether the register is set in the block
2353 and is used to compute "transparency". */
2356 record_last_reg_set_info (insn, regno)
2360 struct reg_avail_info *info = ®_avail_info[regno];
2361 int cuid = INSN_CUID (insn);
2363 info->last_set = cuid;
2364 if (info->last_bb != current_bb)
2366 info->last_bb = current_bb;
2367 info->first_set = cuid;
2368 SET_BIT (reg_set_in_block[current_bb], regno);
2373 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
2374 Note we store a pair of elements in the list, so they have to be
2375 taken off pairwise. */
2378 canon_list_insert (dest, unused1, v_insn)
2379 rtx dest ATTRIBUTE_UNUSED;
2380 rtx unused1 ATTRIBUTE_UNUSED;
2383 rtx dest_addr, insn;
2385 while (GET_CODE (dest) == SUBREG
2386 || GET_CODE (dest) == ZERO_EXTRACT
2387 || GET_CODE (dest) == SIGN_EXTRACT
2388 || GET_CODE (dest) == STRICT_LOW_PART)
2389 dest = XEXP (dest, 0);
2391 /* If DEST is not a MEM, then it will not conflict with a load. Note
2392 that function calls are assumed to clobber memory, but are handled
2395 if (GET_CODE (dest) != MEM)
2398 dest_addr = get_addr (XEXP (dest, 0));
2399 dest_addr = canon_rtx (dest_addr);
2400 insn = (rtx) v_insn;
2402 canon_modify_mem_list[BLOCK_NUM (insn)] =
2403 alloc_INSN_LIST (dest_addr, canon_modify_mem_list[BLOCK_NUM (insn)]);
2404 canon_modify_mem_list[BLOCK_NUM (insn)] =
2405 alloc_INSN_LIST (dest, canon_modify_mem_list[BLOCK_NUM (insn)]);
2408 /* Record memory modification information for INSN. We do not actually care
2409 about the memory location(s) that are set, or even how they are set (consider
2410 a CALL_INSN). We merely need to record which insns modify memory. */
2413 record_last_mem_set_info (insn)
2416 /* load_killed_in_block_p will handle the case of calls clobbering
2418 modify_mem_list[BLOCK_NUM (insn)] =
2419 alloc_INSN_LIST (insn, modify_mem_list[BLOCK_NUM (insn)]);
2421 if (GET_CODE (insn) == CALL_INSN)
2423 /* Note that traversals of this loop (other than for free-ing)
2424 will break after encountering a CALL_INSN. So, there's no
2425 need to insert a pair of items, as canon_list_insert does. */
2426 canon_modify_mem_list[BLOCK_NUM (insn)] =
2427 alloc_INSN_LIST (insn, canon_modify_mem_list[BLOCK_NUM (insn)]);
2430 note_stores (PATTERN (insn), canon_list_insert, (void*)insn );
2433 /* Called from compute_hash_table via note_stores to handle one
2434 SET or CLOBBER in an insn. DATA is really the instruction in which
2435 the SET is taking place. */
2438 record_last_set_info (dest, setter, data)
2439 rtx dest, setter ATTRIBUTE_UNUSED;
2442 rtx last_set_insn = (rtx) data;
2444 if (GET_CODE (dest) == SUBREG)
2445 dest = SUBREG_REG (dest);
2447 if (GET_CODE (dest) == REG)
2448 record_last_reg_set_info (last_set_insn, REGNO (dest));
2449 else if (GET_CODE (dest) == MEM
2450 /* Ignore pushes, they clobber nothing. */
2451 && ! push_operand (dest, GET_MODE (dest)))
2452 record_last_mem_set_info (last_set_insn);
2455 /* Top level function to create an expression or assignment hash table.
2457 Expression entries are placed in the hash table if
2458 - they are of the form (set (pseudo-reg) src),
2459 - src is something we want to perform GCSE on,
2460 - none of the operands are subsequently modified in the block
2462 Assignment entries are placed in the hash table if
2463 - they are of the form (set (pseudo-reg) src),
2464 - src is something we want to perform const/copy propagation on,
2465 - none of the operands or target are subsequently modified in the block
2467 Currently src must be a pseudo-reg or a const_int.
2469 F is the first insn.
2470 SET_P is non-zero for computing the assignment hash table. */
2473 compute_hash_table (set_p)
2478 /* While we compute the hash table we also compute a bit array of which
2479 registers are set in which blocks.
2480 ??? This isn't needed during const/copy propagation, but it's cheap to
2482 sbitmap_vector_zero (reg_set_in_block, n_basic_blocks);
2484 /* re-Cache any INSN_LIST nodes we have allocated. */
2487 for (i = 0; i < n_basic_blocks; i++)
2489 if (modify_mem_list[i])
2490 free_INSN_LIST_list (modify_mem_list + i);
2491 if (canon_modify_mem_list[i])
2492 free_INSN_LIST_list (canon_modify_mem_list + i);
2495 /* Some working arrays used to track first and last set in each block. */
2496 reg_avail_info = (struct reg_avail_info*)
2497 gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
2499 for (i = 0; i < max_gcse_regno; ++i)
2500 reg_avail_info[i].last_bb = NEVER_SET;
2502 for (current_bb = 0; current_bb < n_basic_blocks; current_bb++)
2506 int in_libcall_block;
2508 /* First pass over the instructions records information used to
2509 determine when registers and memory are first and last set.
2510 ??? hard-reg reg_set_in_block computation
2511 could be moved to compute_sets since they currently don't change. */
2513 for (insn = BLOCK_HEAD (current_bb);
2514 insn && insn != NEXT_INSN (BLOCK_END (current_bb));
2515 insn = NEXT_INSN (insn))
2517 if (! INSN_P (insn))
2520 if (GET_CODE (insn) == CALL_INSN)
2522 bool clobbers_all = false;
2523 #ifdef NON_SAVING_SETJMP
2524 if (NON_SAVING_SETJMP
2525 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
2526 clobbers_all = true;
2529 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2531 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2532 record_last_reg_set_info (insn, regno);
2537 note_stores (PATTERN (insn), record_last_set_info, insn);
2540 /* The next pass builds the hash table. */
2542 for (insn = BLOCK_HEAD (current_bb), in_libcall_block = 0;
2543 insn && insn != NEXT_INSN (BLOCK_END (current_bb));
2544 insn = NEXT_INSN (insn))
2547 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2548 in_libcall_block = 1;
2549 else if (set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2550 in_libcall_block = 0;
2551 hash_scan_insn (insn, set_p, in_libcall_block);
2552 if (!set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2553 in_libcall_block = 0;
2557 free (reg_avail_info);
2558 reg_avail_info = NULL;
2561 /* Allocate space for the set hash table.
2562 N_INSNS is the number of instructions in the function.
2563 It is used to determine the number of buckets to use. */
2566 alloc_set_hash_table (n_insns)
2571 set_hash_table_size = n_insns / 4;
2572 if (set_hash_table_size < 11)
2573 set_hash_table_size = 11;
2575 /* Attempt to maintain efficient use of hash table.
2576 Making it an odd number is simplest for now.
2577 ??? Later take some measurements. */
2578 set_hash_table_size |= 1;
2579 n = set_hash_table_size * sizeof (struct expr *);
2580 set_hash_table = (struct expr **) gmalloc (n);
2583 /* Free things allocated by alloc_set_hash_table. */
2586 free_set_hash_table ()
2588 free (set_hash_table);
2591 /* Compute the hash table for doing copy/const propagation. */
2594 compute_set_hash_table ()
2596 /* Initialize count of number of entries in hash table. */
2598 memset ((char *) set_hash_table, 0,
2599 set_hash_table_size * sizeof (struct expr *));
2601 compute_hash_table (1);
2604 /* Allocate space for the expression hash table.
2605 N_INSNS is the number of instructions in the function.
2606 It is used to determine the number of buckets to use. */
2609 alloc_expr_hash_table (n_insns)
2610 unsigned int n_insns;
2614 expr_hash_table_size = n_insns / 2;
2615 /* Make sure the amount is usable. */
2616 if (expr_hash_table_size < 11)
2617 expr_hash_table_size = 11;
2619 /* Attempt to maintain efficient use of hash table.
2620 Making it an odd number is simplest for now.
2621 ??? Later take some measurements. */
2622 expr_hash_table_size |= 1;
2623 n = expr_hash_table_size * sizeof (struct expr *);
2624 expr_hash_table = (struct expr **) gmalloc (n);
2627 /* Free things allocated by alloc_expr_hash_table. */
2630 free_expr_hash_table ()
2632 free (expr_hash_table);
2635 /* Compute the hash table for doing GCSE. */
2638 compute_expr_hash_table ()
2640 /* Initialize count of number of entries in hash table. */
2642 memset ((char *) expr_hash_table, 0,
2643 expr_hash_table_size * sizeof (struct expr *));
2645 compute_hash_table (0);
2648 /* Expression tracking support. */
2650 /* Lookup pattern PAT in the expression table.
2651 The result is a pointer to the table entry, or NULL if not found. */
2653 static struct expr *
2657 int do_not_record_p;
2658 unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p,
2659 expr_hash_table_size);
2662 if (do_not_record_p)
2665 expr = expr_hash_table[hash];
2667 while (expr && ! expr_equiv_p (expr->expr, pat))
2668 expr = expr->next_same_hash;
2673 /* Lookup REGNO in the set table. If PAT is non-NULL look for the entry that
2674 matches it, otherwise return the first entry for REGNO. The result is a
2675 pointer to the table entry, or NULL if not found. */
2677 static struct expr *
2678 lookup_set (regno, pat)
2682 unsigned int hash = hash_set (regno, set_hash_table_size);
2685 expr = set_hash_table[hash];
2689 while (expr && ! expr_equiv_p (expr->expr, pat))
2690 expr = expr->next_same_hash;
2694 while (expr && REGNO (SET_DEST (expr->expr)) != regno)
2695 expr = expr->next_same_hash;
2701 /* Return the next entry for REGNO in list EXPR. */
2703 static struct expr *
2704 next_set (regno, expr)
2709 expr = expr->next_same_hash;
2710 while (expr && REGNO (SET_DEST (expr->expr)) != regno);
2715 /* Reset tables used to keep track of what's still available [since the
2716 start of the block]. */
2719 reset_opr_set_tables ()
2721 /* Maintain a bitmap of which regs have been set since beginning of
2723 sbitmap_zero (reg_set_bitmap);
2725 /* Also keep a record of the last instruction to modify memory.
2726 For now this is very trivial, we only record whether any memory
2727 location has been modified. */
2731 /* re-Cache any INSN_LIST nodes we have allocated. */
2732 for (i = 0; i < n_basic_blocks; i++)
2734 if (modify_mem_list[i])
2735 free_INSN_LIST_list (modify_mem_list + i);
2736 if (canon_modify_mem_list[i])
2737 free_INSN_LIST_list (canon_modify_mem_list + i);
2742 /* Return non-zero if the operands of X are not set before INSN in
2743 INSN's basic block. */
2746 oprs_not_set_p (x, insn)
2756 code = GET_CODE (x);
2771 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn),
2772 INSN_CUID (insn), x, 0))
2775 return oprs_not_set_p (XEXP (x, 0), insn);
2778 return ! TEST_BIT (reg_set_bitmap, REGNO (x));
2784 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2788 /* If we are about to do the last recursive call
2789 needed at this level, change it into iteration.
2790 This function is called enough to be worth it. */
2792 return oprs_not_set_p (XEXP (x, i), insn);
2794 if (! oprs_not_set_p (XEXP (x, i), insn))
2797 else if (fmt[i] == 'E')
2798 for (j = 0; j < XVECLEN (x, i); j++)
2799 if (! oprs_not_set_p (XVECEXP (x, i, j), insn))
2806 /* Mark things set by a CALL. */
2812 if (! CONST_OR_PURE_CALL_P (insn))
2813 record_last_mem_set_info (insn);
2816 /* Mark things set by a SET. */
2819 mark_set (pat, insn)
2822 rtx dest = SET_DEST (pat);
2824 while (GET_CODE (dest) == SUBREG
2825 || GET_CODE (dest) == ZERO_EXTRACT
2826 || GET_CODE (dest) == SIGN_EXTRACT
2827 || GET_CODE (dest) == STRICT_LOW_PART)
2828 dest = XEXP (dest, 0);
2830 if (GET_CODE (dest) == REG)
2831 SET_BIT (reg_set_bitmap, REGNO (dest));
2832 else if (GET_CODE (dest) == MEM)
2833 record_last_mem_set_info (insn);
2835 if (GET_CODE (SET_SRC (pat)) == CALL)
2839 /* Record things set by a CLOBBER. */
2842 mark_clobber (pat, insn)
2845 rtx clob = XEXP (pat, 0);
2847 while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART)
2848 clob = XEXP (clob, 0);
2850 if (GET_CODE (clob) == REG)
2851 SET_BIT (reg_set_bitmap, REGNO (clob));
2853 record_last_mem_set_info (insn);
2856 /* Record things set by INSN.
2857 This data is used by oprs_not_set_p. */
2860 mark_oprs_set (insn)
2863 rtx pat = PATTERN (insn);
2866 if (GET_CODE (pat) == SET)
2867 mark_set (pat, insn);
2868 else if (GET_CODE (pat) == PARALLEL)
2869 for (i = 0; i < XVECLEN (pat, 0); i++)
2871 rtx x = XVECEXP (pat, 0, i);
2873 if (GET_CODE (x) == SET)
2875 else if (GET_CODE (x) == CLOBBER)
2876 mark_clobber (x, insn);
2877 else if (GET_CODE (x) == CALL)
2881 else if (GET_CODE (pat) == CLOBBER)
2882 mark_clobber (pat, insn);
2883 else if (GET_CODE (pat) == CALL)
2888 /* Classic GCSE reaching definition support. */
2890 /* Allocate reaching def variables. */
2893 alloc_rd_mem (n_blocks, n_insns)
2894 int n_blocks, n_insns;
2896 rd_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
2897 sbitmap_vector_zero (rd_kill, n_basic_blocks);
2899 rd_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
2900 sbitmap_vector_zero (rd_gen, n_basic_blocks);
2902 reaching_defs = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
2903 sbitmap_vector_zero (reaching_defs, n_basic_blocks);
2905 rd_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
2906 sbitmap_vector_zero (rd_out, n_basic_blocks);
2909 /* Free reaching def variables. */
2914 sbitmap_vector_free (rd_kill);
2915 sbitmap_vector_free (rd_gen);
2916 sbitmap_vector_free (reaching_defs);
2917 sbitmap_vector_free (rd_out);
2920 /* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
2923 handle_rd_kill_set (insn, regno, bb)
2928 struct reg_set *this_reg;
2930 for (this_reg = reg_set_table[regno]; this_reg; this_reg = this_reg ->next)
2931 if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn))
2932 SET_BIT (rd_kill[bb->index], INSN_CUID (this_reg->insn));
2935 /* Compute the set of kill's for reaching definitions. */
2945 For each set bit in `gen' of the block (i.e each insn which
2946 generates a definition in the block)
2947 Call the reg set by the insn corresponding to that bit regx
2948 Look at the linked list starting at reg_set_table[regx]
2949 For each setting of regx in the linked list, which is not in
2951 Set the bit in `kill' corresponding to that insn. */
2952 for (bb = 0; bb < n_basic_blocks; bb++)
2953 for (cuid = 0; cuid < max_cuid; cuid++)
2954 if (TEST_BIT (rd_gen[bb], cuid))
2956 rtx insn = CUID_INSN (cuid);
2957 rtx pat = PATTERN (insn);
2959 if (GET_CODE (insn) == CALL_INSN)
2961 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2962 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2963 handle_rd_kill_set (insn, regno, BASIC_BLOCK (bb));
2966 if (GET_CODE (pat) == PARALLEL)
2968 for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
2970 enum rtx_code code = GET_CODE (XVECEXP (pat, 0, i));
2972 if ((code == SET || code == CLOBBER)
2973 && GET_CODE (XEXP (XVECEXP (pat, 0, i), 0)) == REG)
2974 handle_rd_kill_set (insn,
2975 REGNO (XEXP (XVECEXP (pat, 0, i), 0)),
2979 else if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == REG)
2980 /* Each setting of this register outside of this block
2981 must be marked in the set of kills in this block. */
2982 handle_rd_kill_set (insn, REGNO (SET_DEST (pat)), BASIC_BLOCK (bb));
2986 /* Compute the reaching definitions as in
2987 Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
2988 Chapter 10. It is the same algorithm as used for computing available
2989 expressions but applied to the gens and kills of reaching definitions. */
2994 int bb, changed, passes;
2996 for (bb = 0; bb < n_basic_blocks; bb++)
2997 sbitmap_copy (rd_out[bb] /*dst*/, rd_gen[bb] /*src*/);
3004 for (bb = 0; bb < n_basic_blocks; bb++)
3006 sbitmap_union_of_preds (reaching_defs[bb], rd_out, bb);
3007 changed |= sbitmap_union_of_diff (rd_out[bb], rd_gen[bb],
3008 reaching_defs[bb], rd_kill[bb]);
3014 fprintf (gcse_file, "reaching def computation: %d passes\n", passes);
3017 /* Classic GCSE available expression support. */
3019 /* Allocate memory for available expression computation. */
3022 alloc_avail_expr_mem (n_blocks, n_exprs)
3023 int n_blocks, n_exprs;
3025 ae_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
3026 sbitmap_vector_zero (ae_kill, n_basic_blocks);
3028 ae_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
3029 sbitmap_vector_zero (ae_gen, n_basic_blocks);
3031 ae_in = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
3032 sbitmap_vector_zero (ae_in, n_basic_blocks);
3034 ae_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
3035 sbitmap_vector_zero (ae_out, n_basic_blocks);
3039 free_avail_expr_mem ()
3041 sbitmap_vector_free (ae_kill);
3042 sbitmap_vector_free (ae_gen);
3043 sbitmap_vector_free (ae_in);
3044 sbitmap_vector_free (ae_out);
3047 /* Compute the set of available expressions generated in each basic block. */
3056 /* For each recorded occurrence of each expression, set ae_gen[bb][expr].
3057 This is all we have to do because an expression is not recorded if it
3058 is not available, and the only expressions we want to work with are the
3059 ones that are recorded. */
3060 for (i = 0; i < expr_hash_table_size; i++)
3061 for (expr = expr_hash_table[i]; expr != 0; expr = expr->next_same_hash)
3062 for (occr = expr->avail_occr; occr != 0; occr = occr->next)
3063 SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index);
3066 /* Return non-zero if expression X is killed in BB. */
3069 expr_killed_p (x, bb)
3080 code = GET_CODE (x);
3084 return TEST_BIT (reg_set_in_block[bb->index], REGNO (x));
3087 if (load_killed_in_block_p (bb, get_max_uid () + 1, x, 0))
3090 return expr_killed_p (XEXP (x, 0), bb);
3107 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3111 /* If we are about to do the last recursive call
3112 needed at this level, change it into iteration.
3113 This function is called enough to be worth it. */
3115 return expr_killed_p (XEXP (x, i), bb);
3116 else if (expr_killed_p (XEXP (x, i), bb))
3119 else if (fmt[i] == 'E')
3120 for (j = 0; j < XVECLEN (x, i); j++)
3121 if (expr_killed_p (XVECEXP (x, i, j), bb))
3128 /* Compute the set of available expressions killed in each basic block. */
3131 compute_ae_kill (ae_gen, ae_kill)
3132 sbitmap *ae_gen, *ae_kill;
3138 for (bb = 0; bb < n_basic_blocks; bb++)
3139 for (i = 0; i < expr_hash_table_size; i++)
3140 for (expr = expr_hash_table[i]; expr; expr = expr->next_same_hash)
3142 /* Skip EXPR if generated in this block. */
3143 if (TEST_BIT (ae_gen[bb], expr->bitmap_index))
3146 if (expr_killed_p (expr->expr, BASIC_BLOCK (bb)))
3147 SET_BIT (ae_kill[bb], expr->bitmap_index);
3151 /* Actually perform the Classic GCSE optimizations. */
3153 /* Return non-zero if occurrence OCCR of expression EXPR reaches block BB.
3155 CHECK_SELF_LOOP is non-zero if we should consider a block reaching itself
3156 as a positive reach. We want to do this when there are two computations
3157 of the expression in the block.
3159 VISITED is a pointer to a working buffer for tracking which BB's have
3160 been visited. It is NULL for the top-level call.
3162 We treat reaching expressions that go through blocks containing the same
3163 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3164 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3165 2 as not reaching. The intent is to improve the probability of finding
3166 only one reaching expression and to reduce register lifetimes by picking
3167 the closest such expression. */
3170 expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited)
3174 int check_self_loop;
3179 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
3181 basic_block pred_bb = pred->src;
3183 if (visited[pred_bb->index])
3184 /* This predecessor has already been visited. Nothing to do. */
3186 else if (pred_bb == bb)
3188 /* BB loops on itself. */
3190 && TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index)
3191 && BLOCK_NUM (occr->insn) == pred_bb->index)
3194 visited[pred_bb->index] = 1;
3197 /* Ignore this predecessor if it kills the expression. */
3198 else if (TEST_BIT (ae_kill[pred_bb->index], expr->bitmap_index))
3199 visited[pred_bb->index] = 1;
3201 /* Does this predecessor generate this expression? */
3202 else if (TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index))
3204 /* Is this the occurrence we're looking for?
3205 Note that there's only one generating occurrence per block
3206 so we just need to check the block number. */
3207 if (BLOCK_NUM (occr->insn) == pred_bb->index)
3210 visited[pred_bb->index] = 1;
3213 /* Neither gen nor kill. */
3216 visited[pred_bb->index] = 1;
3217 if (expr_reaches_here_p_work (occr, expr, pred_bb, check_self_loop,
3224 /* All paths have been checked. */
3228 /* This wrapper for expr_reaches_here_p_work() is to ensure that any
3229 memory allocated for that function is returned. */
3232 expr_reaches_here_p (occr, expr, bb, check_self_loop)
3236 int check_self_loop;
3239 char *visited = (char *) xcalloc (n_basic_blocks, 1);
3241 rval = expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited);
3247 /* Return the instruction that computes EXPR that reaches INSN's basic block.
3248 If there is more than one such instruction, return NULL.
3250 Called only by handle_avail_expr. */
3253 computing_insn (expr, insn)
3257 basic_block bb = BLOCK_FOR_INSN (insn);
3259 if (expr->avail_occr->next == NULL)
3261 if (BLOCK_FOR_INSN (expr->avail_occr->insn) == bb)
3262 /* The available expression is actually itself
3263 (i.e. a loop in the flow graph) so do nothing. */
3266 /* (FIXME) Case that we found a pattern that was created by
3267 a substitution that took place. */
3268 return expr->avail_occr->insn;
3272 /* Pattern is computed more than once.
3273 Search backwards from this insn to see how many of these
3274 computations actually reach this insn. */
3276 rtx insn_computes_expr = NULL;
3279 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
3281 if (BLOCK_FOR_INSN (occr->insn) == bb)
3283 /* The expression is generated in this block.
3284 The only time we care about this is when the expression
3285 is generated later in the block [and thus there's a loop].
3286 We let the normal cse pass handle the other cases. */
3287 if (INSN_CUID (insn) < INSN_CUID (occr->insn)
3288 && expr_reaches_here_p (occr, expr, bb, 1))
3294 insn_computes_expr = occr->insn;
3297 else if (expr_reaches_here_p (occr, expr, bb, 0))
3303 insn_computes_expr = occr->insn;
3307 if (insn_computes_expr == NULL)
3310 return insn_computes_expr;
3314 /* Return non-zero if the definition in DEF_INSN can reach INSN.
3315 Only called by can_disregard_other_sets. */
3318 def_reaches_here_p (insn, def_insn)
3323 if (TEST_BIT (reaching_defs[BLOCK_NUM (insn)], INSN_CUID (def_insn)))
3326 if (BLOCK_NUM (insn) == BLOCK_NUM (def_insn))
3328 if (INSN_CUID (def_insn) < INSN_CUID (insn))
3330 if (GET_CODE (PATTERN (def_insn)) == PARALLEL)
3332 else if (GET_CODE (PATTERN (def_insn)) == CLOBBER)
3333 reg = XEXP (PATTERN (def_insn), 0);
3334 else if (GET_CODE (PATTERN (def_insn)) == SET)
3335 reg = SET_DEST (PATTERN (def_insn));
3339 return ! reg_set_between_p (reg, NEXT_INSN (def_insn), insn);
3348 /* Return non-zero if *ADDR_THIS_REG can only have one value at INSN. The
3349 value returned is the number of definitions that reach INSN. Returning a
3350 value of zero means that [maybe] more than one definition reaches INSN and
3351 the caller can't perform whatever optimization it is trying. i.e. it is
3352 always safe to return zero. */
3355 can_disregard_other_sets (addr_this_reg, insn, for_combine)
3356 struct reg_set **addr_this_reg;
3360 int number_of_reaching_defs = 0;
3361 struct reg_set *this_reg;
3363 for (this_reg = *addr_this_reg; this_reg != 0; this_reg = this_reg->next)
3364 if (def_reaches_here_p (insn, this_reg->insn))
3366 number_of_reaching_defs++;
3367 /* Ignore parallels for now. */
3368 if (GET_CODE (PATTERN (this_reg->insn)) == PARALLEL)
3372 && (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER
3373 || ! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
3374 SET_SRC (PATTERN (insn)))))
3375 /* A setting of the reg to a different value reaches INSN. */
3378 if (number_of_reaching_defs > 1)
3380 /* If in this setting the value the register is being set to is
3381 equal to the previous value the register was set to and this
3382 setting reaches the insn we are trying to do the substitution
3383 on then we are ok. */
3384 if (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER)
3386 else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
3387 SET_SRC (PATTERN (insn))))
3391 *addr_this_reg = this_reg;
3394 return number_of_reaching_defs;
3397 /* Expression computed by insn is available and the substitution is legal,
3398 so try to perform the substitution.
3400 The result is non-zero if any changes were made. */
3403 handle_avail_expr (insn, expr)
3407 rtx pat, insn_computes_expr, expr_set;
3409 struct reg_set *this_reg;
3410 int found_setting, use_src;
3413 /* We only handle the case where one computation of the expression
3414 reaches this instruction. */
3415 insn_computes_expr = computing_insn (expr, insn);
3416 if (insn_computes_expr == NULL)
3418 expr_set = single_set (insn_computes_expr);
3425 /* At this point we know only one computation of EXPR outside of this
3426 block reaches this insn. Now try to find a register that the
3427 expression is computed into. */
3428 if (GET_CODE (SET_SRC (expr_set)) == REG)
3430 /* This is the case when the available expression that reaches
3431 here has already been handled as an available expression. */
3432 unsigned int regnum_for_replacing
3433 = REGNO (SET_SRC (expr_set));
3435 /* If the register was created by GCSE we can't use `reg_set_table',
3436 however we know it's set only once. */
3437 if (regnum_for_replacing >= max_gcse_regno
3438 /* If the register the expression is computed into is set only once,
3439 or only one set reaches this insn, we can use it. */
3440 || (((this_reg = reg_set_table[regnum_for_replacing]),
3441 this_reg->next == NULL)
3442 || can_disregard_other_sets (&this_reg, insn, 0)))
3451 unsigned int regnum_for_replacing
3452 = REGNO (SET_DEST (expr_set));
3454 /* This shouldn't happen. */
3455 if (regnum_for_replacing >= max_gcse_regno)
3458 this_reg = reg_set_table[regnum_for_replacing];
3460 /* If the register the expression is computed into is set only once,
3461 or only one set reaches this insn, use it. */
3462 if (this_reg->next == NULL
3463 || can_disregard_other_sets (&this_reg, insn, 0))
3469 pat = PATTERN (insn);
3471 to = SET_SRC (expr_set);
3473 to = SET_DEST (expr_set);
3474 changed = validate_change (insn, &SET_SRC (pat), to, 0);
3476 /* We should be able to ignore the return code from validate_change but
3477 to play it safe we check. */
3481 if (gcse_file != NULL)
3483 fprintf (gcse_file, "GCSE: Replacing the source in insn %d with",
3485 fprintf (gcse_file, " reg %d %s insn %d\n",
3486 REGNO (to), use_src ? "from" : "set in",
3487 INSN_UID (insn_computes_expr));
3492 /* The register that the expr is computed into is set more than once. */
3493 else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
3495 /* Insert an insn after insnx that copies the reg set in insnx
3496 into a new pseudo register call this new register REGN.
3497 From insnb until end of basic block or until REGB is set
3498 replace all uses of REGB with REGN. */
3501 to = gen_reg_rtx (GET_MODE (SET_DEST (expr_set)));
3503 /* Generate the new insn. */
3504 /* ??? If the change fails, we return 0, even though we created
3505 an insn. I think this is ok. */
3507 = emit_insn_after (gen_rtx_SET (VOIDmode, to,
3508 SET_DEST (expr_set)),
3509 insn_computes_expr);
3511 /* Keep block number table up to date. */
3512 set_block_for_new_insns (new_insn, BLOCK_FOR_INSN (insn_computes_expr));
3514 /* Keep register set table up to date. */
3515 record_one_set (REGNO (to), new_insn);
3517 gcse_create_count++;
3518 if (gcse_file != NULL)
3520 fprintf (gcse_file, "GCSE: Creating insn %d to copy value of reg %d",
3521 INSN_UID (NEXT_INSN (insn_computes_expr)),
3522 REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr)))));
3523 fprintf (gcse_file, ", computed in insn %d,\n",
3524 INSN_UID (insn_computes_expr));
3525 fprintf (gcse_file, " into newly allocated reg %d\n",
3529 pat = PATTERN (insn);
3531 /* Do register replacement for INSN. */
3532 changed = validate_change (insn, &SET_SRC (pat),
3534 (NEXT_INSN (insn_computes_expr))),
3537 /* We should be able to ignore the return code from validate_change but
3538 to play it safe we check. */
3542 if (gcse_file != NULL)
3545 "GCSE: Replacing the source in insn %d with reg %d ",
3547 REGNO (SET_DEST (PATTERN (NEXT_INSN
3548 (insn_computes_expr)))));
3549 fprintf (gcse_file, "set in insn %d\n",
3550 INSN_UID (insn_computes_expr));
3558 /* Perform classic GCSE. This is called by one_classic_gcse_pass after all
3559 the dataflow analysis has been done.
3561 The result is non-zero if a change was made. */
3569 /* Note we start at block 1. */
3572 for (bb = 1; bb < n_basic_blocks; bb++)
3574 /* Reset tables used to keep track of what's still valid [since the
3575 start of the block]. */
3576 reset_opr_set_tables ();
3578 for (insn = BLOCK_HEAD (bb);
3579 insn != NULL && insn != NEXT_INSN (BLOCK_END (bb));
3580 insn = NEXT_INSN (insn))
3582 /* Is insn of form (set (pseudo-reg) ...)? */
3583 if (GET_CODE (insn) == INSN
3584 && GET_CODE (PATTERN (insn)) == SET
3585 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
3586 && REGNO (SET_DEST (PATTERN (insn))) >= FIRST_PSEUDO_REGISTER)
3588 rtx pat = PATTERN (insn);
3589 rtx src = SET_SRC (pat);
3592 if (want_to_gcse_p (src)
3593 /* Is the expression recorded? */
3594 && ((expr = lookup_expr (src)) != NULL)
3595 /* Is the expression available [at the start of the
3597 && TEST_BIT (ae_in[bb], expr->bitmap_index)
3598 /* Are the operands unchanged since the start of the
3600 && oprs_not_set_p (src, insn))
3601 changed |= handle_avail_expr (insn, expr);
3604 /* Keep track of everything modified by this insn. */
3605 /* ??? Need to be careful w.r.t. mods done to INSN. */
3607 mark_oprs_set (insn);
3614 /* Top level routine to perform one classic GCSE pass.
3616 Return non-zero if a change was made. */
3619 one_classic_gcse_pass (pass)
3624 gcse_subst_count = 0;
3625 gcse_create_count = 0;
3627 alloc_expr_hash_table (max_cuid);
3628 alloc_rd_mem (n_basic_blocks, max_cuid);
3629 compute_expr_hash_table ();
3631 dump_hash_table (gcse_file, "Expression", expr_hash_table,
3632 expr_hash_table_size, n_exprs);
3638 alloc_avail_expr_mem (n_basic_blocks, n_exprs);
3640 compute_ae_kill (ae_gen, ae_kill);
3641 compute_available (ae_gen, ae_kill, ae_out, ae_in);
3642 changed = classic_gcse ();
3643 free_avail_expr_mem ();
3647 free_expr_hash_table ();
3651 fprintf (gcse_file, "\n");
3652 fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
3653 current_function_name, pass, bytes_used, gcse_subst_count);
3654 fprintf (gcse_file, "%d insns created\n", gcse_create_count);
3660 /* Compute copy/constant propagation working variables. */
3662 /* Local properties of assignments. */
3663 static sbitmap *cprop_pavloc;
3664 static sbitmap *cprop_absaltered;
3666 /* Global properties of assignments (computed from the local properties). */
3667 static sbitmap *cprop_avin;
3668 static sbitmap *cprop_avout;
3670 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
3671 basic blocks. N_SETS is the number of sets. */
3674 alloc_cprop_mem (n_blocks, n_sets)
3675 int n_blocks, n_sets;
3677 cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
3678 cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
3680 cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
3681 cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
3684 /* Free vars used by copy/const propagation. */
3689 sbitmap_vector_free (cprop_pavloc);
3690 sbitmap_vector_free (cprop_absaltered);
3691 sbitmap_vector_free (cprop_avin);
3692 sbitmap_vector_free (cprop_avout);
3695 /* For each block, compute whether X is transparent. X is either an
3696 expression or an assignment [though we don't care which, for this context
3697 an assignment is treated as an expression]. For each block where an
3698 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
3702 compute_transp (x, indx, bmap, set_p)
3713 /* repeat is used to turn tail-recursion into iteration since GCC
3714 can't do it when there's no return value. */
3720 code = GET_CODE (x);
3726 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
3728 for (bb = 0; bb < n_basic_blocks; bb++)
3729 if (TEST_BIT (reg_set_in_block[bb], REGNO (x)))
3730 SET_BIT (bmap[bb], indx);
3734 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
3735 SET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
3740 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
3742 for (bb = 0; bb < n_basic_blocks; bb++)
3743 if (TEST_BIT (reg_set_in_block[bb], REGNO (x)))
3744 RESET_BIT (bmap[bb], indx);
3748 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
3749 RESET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
3756 for (bb = 0; bb < n_basic_blocks; bb++)
3758 rtx list_entry = canon_modify_mem_list[bb];
3762 rtx dest, dest_addr;
3764 if (GET_CODE (XEXP (list_entry, 0)) == CALL_INSN)
3767 SET_BIT (bmap[bb], indx);
3769 RESET_BIT (bmap[bb], indx);
3772 /* LIST_ENTRY must be an INSN of some kind that sets memory.
3773 Examine each hunk of memory that is modified. */
3775 dest = XEXP (list_entry, 0);
3776 list_entry = XEXP (list_entry, 1);
3777 dest_addr = XEXP (list_entry, 0);
3779 if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
3780 x, rtx_addr_varies_p))
3783 SET_BIT (bmap[bb], indx);
3785 RESET_BIT (bmap[bb], indx);
3788 list_entry = XEXP (list_entry, 1);
3810 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3814 /* If we are about to do the last recursive call
3815 needed at this level, change it into iteration.
3816 This function is called enough to be worth it. */
3823 compute_transp (XEXP (x, i), indx, bmap, set_p);
3825 else if (fmt[i] == 'E')
3826 for (j = 0; j < XVECLEN (x, i); j++)
3827 compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
3831 /* Top level routine to do the dataflow analysis needed by copy/const
3835 compute_cprop_data ()
3837 compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, 1);
3838 compute_available (cprop_pavloc, cprop_absaltered,
3839 cprop_avout, cprop_avin);
3842 /* Copy/constant propagation. */
3844 /* Maximum number of register uses in an insn that we handle. */
3847 /* Table of uses found in an insn.
3848 Allocated statically to avoid alloc/free complexity and overhead. */
3849 static struct reg_use reg_use_table[MAX_USES];
3851 /* Index into `reg_use_table' while building it. */
3852 static int reg_use_count;
3854 /* Set up a list of register numbers used in INSN. The found uses are stored
3855 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
3856 and contains the number of uses in the table upon exit.
3858 ??? If a register appears multiple times we will record it multiple times.
3859 This doesn't hurt anything but it will slow things down. */
3862 find_used_regs (xptr, data)
3864 void *data ATTRIBUTE_UNUSED;
3871 /* repeat is used to turn tail-recursion into iteration since GCC
3872 can't do it when there's no return value. */
3877 code = GET_CODE (x);
3880 if (reg_use_count == MAX_USES)
3883 reg_use_table[reg_use_count].reg_rtx = x;
3887 /* Recursively scan the operands of this expression. */
3889 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3893 /* If we are about to do the last recursive call
3894 needed at this level, change it into iteration.
3895 This function is called enough to be worth it. */
3902 find_used_regs (&XEXP (x, i), data);
3904 else if (fmt[i] == 'E')
3905 for (j = 0; j < XVECLEN (x, i); j++)
3906 find_used_regs (&XVECEXP (x, i, j), data);
3910 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
3911 Returns non-zero is successful. */
3914 try_replace_reg (from, to, insn)
3917 rtx note = find_reg_equal_equiv_note (insn);
3920 rtx set = single_set (insn);
3922 success = validate_replace_src (from, to, insn);
3924 /* If above failed and this is a single set, try to simplify the source of
3925 the set given our substitution. We could perhaps try this for multiple
3926 SETs, but it probably won't buy us anything. */
3927 if (!success && set != 0)
3929 src = simplify_replace_rtx (SET_SRC (set), from, to);
3931 if (!rtx_equal_p (src, SET_SRC (set))
3932 && validate_change (insn, &SET_SRC (set), src, 0))
3936 /* If we've failed to do replacement, have a single SET, and don't already
3937 have a note, add a REG_EQUAL note to not lose information. */
3938 if (!success && note == 0 && set != 0)
3939 note = REG_NOTES (insn)
3940 = gen_rtx_EXPR_LIST (REG_EQUAL, src, REG_NOTES (insn));
3942 /* If there is already a NOTE, update the expression in it with our
3945 XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to);
3947 /* REG_EQUAL may get simplified into register.
3948 We don't allow that. Remove that note. This code ought
3949 not to hapen, because previous code ought to syntetize
3950 reg-reg move, but be on the safe side. */
3951 if (note && REG_P (XEXP (note, 0)))
3952 remove_note (insn, note);
3957 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
3958 NULL no such set is found. */
3960 static struct expr *
3961 find_avail_set (regno, insn)
3965 /* SET1 contains the last set found that can be returned to the caller for
3966 use in a substitution. */
3967 struct expr *set1 = 0;
3969 /* Loops are not possible here. To get a loop we would need two sets
3970 available at the start of the block containing INSN. ie we would
3971 need two sets like this available at the start of the block:
3973 (set (reg X) (reg Y))
3974 (set (reg Y) (reg X))
3976 This can not happen since the set of (reg Y) would have killed the
3977 set of (reg X) making it unavailable at the start of this block. */
3981 struct expr *set = lookup_set (regno, NULL_RTX);
3983 /* Find a set that is available at the start of the block
3984 which contains INSN. */
3987 if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
3989 set = next_set (regno, set);
3992 /* If no available set was found we've reached the end of the
3993 (possibly empty) copy chain. */
3997 if (GET_CODE (set->expr) != SET)
4000 src = SET_SRC (set->expr);
4002 /* We know the set is available.
4003 Now check that SRC is ANTLOC (i.e. none of the source operands
4004 have changed since the start of the block).
4006 If the source operand changed, we may still use it for the next
4007 iteration of this loop, but we may not use it for substitutions. */
4009 if (CONSTANT_P (src) || oprs_not_set_p (src, insn))
4012 /* If the source of the set is anything except a register, then
4013 we have reached the end of the copy chain. */
4014 if (GET_CODE (src) != REG)
4017 /* Follow the copy chain, ie start another iteration of the loop
4018 and see if we have an available copy into SRC. */
4019 regno = REGNO (src);
4022 /* SET1 holds the last set that was available and anticipatable at
4027 /* Subroutine of cprop_insn that tries to propagate constants into
4028 JUMP_INSNS. INSN must be a conditional jump. FROM is what we will try to
4029 replace, SRC is the constant we will try to substitute for it. Returns
4030 nonzero if a change was made. We know INSN has just a SET. */
4033 cprop_jump (bb, insn, from, src)
4039 rtx set = PATTERN (insn);
4040 rtx new = simplify_replace_rtx (SET_SRC (set), from, src);
4042 /* If no simplification can be made, then try the next
4044 if (rtx_equal_p (new, SET_SRC (set)))
4047 /* If this is now a no-op leave it that way, but update LABEL_NUSED if
4051 SET_SRC (set) = new;
4053 if (JUMP_LABEL (insn) != 0)
4054 --LABEL_NUSES (JUMP_LABEL (insn));
4057 /* Otherwise, this must be a valid instruction. */
4058 else if (! validate_change (insn, &SET_SRC (set), new, 0))
4061 /* If this has turned into an unconditional jump,
4062 then put a barrier after it so that the unreachable
4063 code will be deleted. */
4064 if (GET_CODE (SET_SRC (set)) == LABEL_REF)
4065 emit_barrier_after (insn);
4067 run_jump_opt_after_gcse = 1;
4070 if (gcse_file != NULL)
4073 "CONST-PROP: Replacing reg %d in insn %d with constant ",
4074 REGNO (from), INSN_UID (insn));
4075 print_rtl (gcse_file, src);
4076 fprintf (gcse_file, "\n");
4078 purge_dead_edges (bb);
4085 /* Subroutine of cprop_insn that tries to propagate constants into JUMP_INSNS
4086 for machines that have CC0. INSN is a single set that stores into CC0;
4087 the insn following it is a conditional jump. REG_USED is the use we will
4088 try to replace, SRC is the constant we will try to substitute for it.
4089 Returns nonzero if a change was made. */
4092 cprop_cc0_jump (bb, insn, reg_used, src)
4095 struct reg_use *reg_used;
4098 /* First substitute in the SET_SRC of INSN, then substitute that for
4100 rtx jump = NEXT_INSN (insn);
4101 rtx new_src = simplify_replace_rtx (SET_SRC (PATTERN (insn)),
4102 reg_used->reg_rtx, src);
4104 if (! cprop_jump (bb, jump, cc0_rtx, new_src))
4107 /* If we succeeded, delete the cc0 setter. */
4108 PUT_CODE (insn, NOTE);
4109 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
4110 NOTE_SOURCE_FILE (insn) = 0;
4116 /* Perform constant and copy propagation on INSN.
4117 The result is non-zero if a change was made. */
4120 cprop_insn (bb, insn, alter_jumps)
4125 struct reg_use *reg_used;
4133 note_uses (&PATTERN (insn), find_used_regs, NULL);
4135 note = find_reg_equal_equiv_note (insn);
4137 /* We may win even when propagating constants into notes. */
4139 find_used_regs (&XEXP (note, 0), NULL);
4141 for (reg_used = ®_use_table[0]; reg_use_count > 0;
4142 reg_used++, reg_use_count--)
4144 unsigned int regno = REGNO (reg_used->reg_rtx);
4148 /* Ignore registers created by GCSE.
4149 We do this because ... */
4150 if (regno >= max_gcse_regno)
4153 /* If the register has already been set in this block, there's
4154 nothing we can do. */
4155 if (! oprs_not_set_p (reg_used->reg_rtx, insn))
4158 /* Find an assignment that sets reg_used and is available
4159 at the start of the block. */
4160 set = find_avail_set (regno, insn);
4165 /* ??? We might be able to handle PARALLELs. Later. */
4166 if (GET_CODE (pat) != SET)
4169 src = SET_SRC (pat);
4171 /* Constant propagation. */
4172 if (GET_CODE (src) == CONST_INT || GET_CODE (src) == CONST_DOUBLE
4173 || GET_CODE (src) == SYMBOL_REF)
4175 /* Handle normal insns first. */
4176 if (GET_CODE (insn) == INSN
4177 && try_replace_reg (reg_used->reg_rtx, src, insn))
4181 if (gcse_file != NULL)
4183 fprintf (gcse_file, "CONST-PROP: Replacing reg %d in ",
4185 fprintf (gcse_file, "insn %d with constant ",
4187 print_rtl (gcse_file, src);
4188 fprintf (gcse_file, "\n");
4191 /* The original insn setting reg_used may or may not now be
4192 deletable. We leave the deletion to flow. */
4195 /* Try to propagate a CONST_INT into a conditional jump.
4196 We're pretty specific about what we will handle in this
4197 code, we can extend this as necessary over time.
4199 Right now the insn in question must look like
4200 (set (pc) (if_then_else ...)) */
4201 else if (alter_jumps
4202 && GET_CODE (insn) == JUMP_INSN
4203 && condjump_p (insn)
4204 && ! simplejump_p (insn))
4205 changed |= cprop_jump (bb, insn, reg_used->reg_rtx, src);
4208 /* Similar code for machines that use a pair of CC0 setter and
4209 conditional jump insn. */
4210 else if (alter_jumps
4211 && GET_CODE (PATTERN (insn)) == SET
4212 && SET_DEST (PATTERN (insn)) == cc0_rtx
4213 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
4214 && condjump_p (NEXT_INSN (insn))
4215 && ! simplejump_p (NEXT_INSN (insn))
4216 && cprop_cc0_jump (bb, insn, reg_used, src))
4223 else if (GET_CODE (src) == REG
4224 && REGNO (src) >= FIRST_PSEUDO_REGISTER
4225 && REGNO (src) != regno)
4227 if (try_replace_reg (reg_used->reg_rtx, src, insn))
4231 if (gcse_file != NULL)
4233 fprintf (gcse_file, "COPY-PROP: Replacing reg %d in insn %d",
4234 regno, INSN_UID (insn));
4235 fprintf (gcse_file, " with reg %d\n", REGNO (src));
4238 /* The original insn setting reg_used may or may not now be
4239 deletable. We leave the deletion to flow. */
4240 /* FIXME: If it turns out that the insn isn't deletable,
4241 then we may have unnecessarily extended register lifetimes
4242 and made things worse. */
4250 /* Forward propagate copies. This includes copies and constants. Return
4251 non-zero if a change was made. */
4260 /* Note we start at block 1. */
4263 for (bb = 1; bb < n_basic_blocks; bb++)
4265 /* Reset tables used to keep track of what's still valid [since the
4266 start of the block]. */
4267 reset_opr_set_tables ();
4269 for (insn = BLOCK_HEAD (bb);
4270 insn != NULL && insn != NEXT_INSN (BLOCK_END (bb));
4271 insn = NEXT_INSN (insn))
4274 changed |= cprop_insn (BASIC_BLOCK (bb), insn, alter_jumps);
4276 /* Keep track of everything modified by this insn. */
4277 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
4278 call mark_oprs_set if we turned the insn into a NOTE. */
4279 if (GET_CODE (insn) != NOTE)
4280 mark_oprs_set (insn);
4284 if (gcse_file != NULL)
4285 fprintf (gcse_file, "\n");
4290 /* Perform one copy/constant propagation pass.
4291 F is the first insn in the function.
4292 PASS is the pass count. */
4295 one_cprop_pass (pass, alter_jumps)
4301 const_prop_count = 0;
4302 copy_prop_count = 0;
4304 alloc_set_hash_table (max_cuid);
4305 compute_set_hash_table ();
4307 dump_hash_table (gcse_file, "SET", set_hash_table, set_hash_table_size,
4311 alloc_cprop_mem (n_basic_blocks, n_sets);
4312 compute_cprop_data ();
4313 changed = cprop (alter_jumps);
4317 free_set_hash_table ();
4321 fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, ",
4322 current_function_name, pass, bytes_used);
4323 fprintf (gcse_file, "%d const props, %d copy props\n\n",
4324 const_prop_count, copy_prop_count);
4330 /* Compute PRE+LCM working variables. */
4332 /* Local properties of expressions. */
4333 /* Nonzero for expressions that are transparent in the block. */
4334 static sbitmap *transp;
4336 /* Nonzero for expressions that are transparent at the end of the block.
4337 This is only zero for expressions killed by abnormal critical edge
4338 created by a calls. */
4339 static sbitmap *transpout;
4341 /* Nonzero for expressions that are computed (available) in the block. */
4342 static sbitmap *comp;
4344 /* Nonzero for expressions that are locally anticipatable in the block. */
4345 static sbitmap *antloc;
4347 /* Nonzero for expressions where this block is an optimal computation
4349 static sbitmap *pre_optimal;
4351 /* Nonzero for expressions which are redundant in a particular block. */
4352 static sbitmap *pre_redundant;
4354 /* Nonzero for expressions which should be inserted on a specific edge. */
4355 static sbitmap *pre_insert_map;
4357 /* Nonzero for expressions which should be deleted in a specific block. */
4358 static sbitmap *pre_delete_map;
4360 /* Contains the edge_list returned by pre_edge_lcm. */
4361 static struct edge_list *edge_list;
4363 /* Redundant insns. */
4364 static sbitmap pre_redundant_insns;
4366 /* Allocate vars used for PRE analysis. */
4369 alloc_pre_mem (n_blocks, n_exprs)
4370 int n_blocks, n_exprs;
4372 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
4373 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
4374 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
4377 pre_redundant = NULL;
4378 pre_insert_map = NULL;
4379 pre_delete_map = NULL;
4382 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
4384 /* pre_insert and pre_delete are allocated later. */
4387 /* Free vars used for PRE analysis. */
4392 sbitmap_vector_free (transp);
4393 sbitmap_vector_free (comp);
4395 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
4398 sbitmap_vector_free (pre_optimal);
4400 sbitmap_vector_free (pre_redundant);
4402 sbitmap_vector_free (pre_insert_map);
4404 sbitmap_vector_free (pre_delete_map);
4406 sbitmap_vector_free (ae_in);
4408 sbitmap_vector_free (ae_out);
4410 transp = comp = NULL;
4411 pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
4412 ae_in = ae_out = NULL;
4415 /* Top level routine to do the dataflow analysis needed by PRE. */
4420 sbitmap trapping_expr;
4424 compute_local_properties (transp, comp, antloc, 0);
4425 sbitmap_vector_zero (ae_kill, n_basic_blocks);
4427 /* Collect expressions which might trap. */
4428 trapping_expr = sbitmap_alloc (n_exprs);
4429 sbitmap_zero (trapping_expr);
4430 for (ui = 0; ui < expr_hash_table_size; ui++)
4433 for (e = expr_hash_table[ui]; e != NULL; e = e->next_same_hash)
4434 if (may_trap_p (e->expr))
4435 SET_BIT (trapping_expr, e->bitmap_index);
4438 /* Compute ae_kill for each basic block using:
4442 This is significantly faster than compute_ae_kill. */
4444 for (i = 0; i < n_basic_blocks; i++)
4448 /* If the current block is the destination of an abnormal edge, we
4449 kill all trapping expressions because we won't be able to properly
4450 place the instruction on the edge. So make them neither
4451 anticipatable nor transparent. This is fairly conservative. */
4452 for (e = BASIC_BLOCK (i)->pred; e ; e = e->pred_next)
4453 if (e->flags & EDGE_ABNORMAL)
4455 sbitmap_difference (antloc[i], antloc[i], trapping_expr);
4456 sbitmap_difference (transp[i], transp[i], trapping_expr);
4460 sbitmap_a_or_b (ae_kill[i], transp[i], comp[i]);
4461 sbitmap_not (ae_kill[i], ae_kill[i]);
4464 edge_list = pre_edge_lcm (gcse_file, n_exprs, transp, comp, antloc,
4465 ae_kill, &pre_insert_map, &pre_delete_map);
4466 sbitmap_vector_free (antloc);
4468 sbitmap_vector_free (ae_kill);
4470 free (trapping_expr);
4475 /* Return non-zero if an occurrence of expression EXPR in OCCR_BB would reach
4478 VISITED is a pointer to a working buffer for tracking which BB's have
4479 been visited. It is NULL for the top-level call.
4481 We treat reaching expressions that go through blocks containing the same
4482 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
4483 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
4484 2 as not reaching. The intent is to improve the probability of finding
4485 only one reaching expression and to reduce register lifetimes by picking
4486 the closest such expression. */
4489 pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited)
4490 basic_block occr_bb;
4497 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
4499 basic_block pred_bb = pred->src;
4501 if (pred->src == ENTRY_BLOCK_PTR
4502 /* Has predecessor has already been visited? */
4503 || visited[pred_bb->index])
4504 ;/* Nothing to do. */
4506 /* Does this predecessor generate this expression? */
4507 else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
4509 /* Is this the occurrence we're looking for?
4510 Note that there's only one generating occurrence per block
4511 so we just need to check the block number. */
4512 if (occr_bb == pred_bb)
4515 visited[pred_bb->index] = 1;
4517 /* Ignore this predecessor if it kills the expression. */
4518 else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
4519 visited[pred_bb->index] = 1;
4521 /* Neither gen nor kill. */
4524 visited[pred_bb->index] = 1;
4525 if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
4530 /* All paths have been checked. */
4534 /* The wrapper for pre_expr_reaches_here_work that ensures that any
4535 memory allocated for that function is returned. */
4538 pre_expr_reaches_here_p (occr_bb, expr, bb)
4539 basic_block occr_bb;
4544 char *visited = (char *) xcalloc (n_basic_blocks, 1);
4546 rval = pre_expr_reaches_here_p_work(occr_bb, expr, bb, visited);
4553 /* Given an expr, generate RTL which we can insert at the end of a BB,
4554 or on an edge. Set the block number of any insns generated to
4558 process_insert_insn (expr)
4561 rtx reg = expr->reaching_reg;
4562 rtx exp = copy_rtx (expr->expr);
4567 /* If the expression is something that's an operand, like a constant,
4568 just copy it to a register. */
4569 if (general_operand (exp, GET_MODE (reg)))
4570 emit_move_insn (reg, exp);
4572 /* Otherwise, make a new insn to compute this expression and make sure the
4573 insn will be recognized (this also adds any needed CLOBBERs). Copy the
4574 expression to make sure we don't have any sharing issues. */
4575 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode, reg, exp))))
4578 pat = gen_sequence ();
4584 /* Add EXPR to the end of basic block BB.
4586 This is used by both the PRE and code hoisting.
4588 For PRE, we want to verify that the expr is either transparent
4589 or locally anticipatable in the target block. This check makes
4590 no sense for code hoisting. */
4593 insert_insn_end_bb (expr, bb, pre)
4600 rtx reg = expr->reaching_reg;
4601 int regno = REGNO (reg);
4605 pat = process_insert_insn (expr);
4607 /* If the last insn is a jump, insert EXPR in front [taking care to
4608 handle cc0, etc. properly]. */
4610 if (GET_CODE (insn) == JUMP_INSN)
4616 /* If this is a jump table, then we can't insert stuff here. Since
4617 we know the previous real insn must be the tablejump, we insert
4618 the new instruction just before the tablejump. */
4619 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
4620 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
4621 insn = prev_real_insn (insn);
4624 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4625 if cc0 isn't set. */
4626 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
4628 insn = XEXP (note, 0);
4631 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
4632 if (maybe_cc0_setter
4633 && INSN_P (maybe_cc0_setter)
4634 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
4635 insn = maybe_cc0_setter;
4638 /* FIXME: What if something in cc0/jump uses value set in new insn? */
4639 new_insn = emit_block_insn_before (pat, insn, bb);
4642 /* Likewise if the last insn is a call, as will happen in the presence
4643 of exception handling. */
4644 else if (GET_CODE (insn) == CALL_INSN)
4646 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
4647 we search backward and place the instructions before the first
4648 parameter is loaded. Do this for everyone for consistency and a
4649 presumtion that we'll get better code elsewhere as well.
4651 It should always be the case that we can put these instructions
4652 anywhere in the basic block with performing PRE optimizations.
4656 && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
4657 && !TEST_BIT (transp[bb->index], expr->bitmap_index))
4660 /* Since different machines initialize their parameter registers
4661 in different orders, assume nothing. Collect the set of all
4662 parameter registers. */
4663 insn = find_first_parameter_load (insn, bb->head);
4665 /* If we found all the parameter loads, then we want to insert
4666 before the first parameter load.
4668 If we did not find all the parameter loads, then we might have
4669 stopped on the head of the block, which could be a CODE_LABEL.
4670 If we inserted before the CODE_LABEL, then we would be putting
4671 the insn in the wrong basic block. In that case, put the insn
4672 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
4673 while (GET_CODE (insn) == CODE_LABEL
4674 || NOTE_INSN_BASIC_BLOCK_P (insn))
4675 insn = NEXT_INSN (insn);
4677 new_insn = emit_block_insn_before (pat, insn, bb);
4681 new_insn = emit_insn_after (pat, insn);
4685 /* Keep block number table up to date.
4686 Note, PAT could be a multiple insn sequence, we have to make
4687 sure that each insn in the sequence is handled. */
4688 if (GET_CODE (pat) == SEQUENCE)
4690 for (i = 0; i < XVECLEN (pat, 0); i++)
4692 rtx insn = XVECEXP (pat, 0, i);
4694 set_block_for_insn (insn, bb);
4696 add_label_notes (PATTERN (insn), new_insn);
4698 note_stores (PATTERN (insn), record_set_info, insn);
4703 add_label_notes (SET_SRC (pat), new_insn);
4704 set_block_for_new_insns (new_insn, bb);
4706 /* Keep register set table up to date. */
4707 record_one_set (regno, new_insn);
4710 gcse_create_count++;
4714 fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, ",
4715 bb->index, INSN_UID (new_insn));
4716 fprintf (gcse_file, "copying expression %d to reg %d\n",
4717 expr->bitmap_index, regno);
4721 /* Insert partially redundant expressions on edges in the CFG to make
4722 the expressions fully redundant. */
4725 pre_edge_insert (edge_list, index_map)
4726 struct edge_list *edge_list;
4727 struct expr **index_map;
4729 int e, i, j, num_edges, set_size, did_insert = 0;
4732 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
4733 if it reaches any of the deleted expressions. */
4735 set_size = pre_insert_map[0]->size;
4736 num_edges = NUM_EDGES (edge_list);
4737 inserted = sbitmap_vector_alloc (num_edges, n_exprs);
4738 sbitmap_vector_zero (inserted, num_edges);
4740 for (e = 0; e < num_edges; e++)
4743 basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
4745 for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
4747 SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
4749 for (j = indx; insert && j < n_exprs; j++, insert >>= 1)
4750 if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
4752 struct expr *expr = index_map[j];
4755 /* Now look at each deleted occurence of this expression. */
4756 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4758 if (! occr->deleted_p)
4761 /* Insert this expression on this edge if if it would
4762 reach the deleted occurence in BB. */
4763 if (!TEST_BIT (inserted[e], j))
4766 edge eg = INDEX_EDGE (edge_list, e);
4768 /* We can't insert anything on an abnormal and
4769 critical edge, so we insert the insn at the end of
4770 the previous block. There are several alternatives
4771 detailed in Morgans book P277 (sec 10.5) for
4772 handling this situation. This one is easiest for
4775 if ((eg->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
4776 insert_insn_end_bb (index_map[j], bb, 0);
4779 insn = process_insert_insn (index_map[j]);
4780 insert_insn_on_edge (insn, eg);
4785 fprintf (gcse_file, "PRE/HOIST: edge (%d,%d), ",
4787 INDEX_EDGE_SUCC_BB (edge_list, e)->index);
4788 fprintf (gcse_file, "copy expression %d\n",
4789 expr->bitmap_index);
4792 update_ld_motion_stores (expr);
4793 SET_BIT (inserted[e], j);
4795 gcse_create_count++;
4802 sbitmap_vector_free (inserted);
4806 /* Copy the result of INSN to REG. INDX is the expression number. */
4809 pre_insert_copy_insn (expr, insn)
4813 rtx reg = expr->reaching_reg;
4814 int regno = REGNO (reg);
4815 int indx = expr->bitmap_index;
4816 rtx set = single_set (insn);
4818 basic_block bb = BLOCK_FOR_INSN (insn);
4823 new_insn = emit_insn_after (gen_move_insn (reg, SET_DEST (set)), insn);
4825 /* Keep block number table up to date. */
4826 set_block_for_new_insns (new_insn, bb);
4828 /* Keep register set table up to date. */
4829 record_one_set (regno, new_insn);
4830 if (insn == bb->end)
4833 gcse_create_count++;
4837 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
4838 BLOCK_NUM (insn), INSN_UID (new_insn), indx,
4839 INSN_UID (insn), regno);
4840 update_ld_motion_stores (expr);
4843 /* Copy available expressions that reach the redundant expression
4844 to `reaching_reg'. */
4847 pre_insert_copies ()
4854 /* For each available expression in the table, copy the result to
4855 `reaching_reg' if the expression reaches a deleted one.
4857 ??? The current algorithm is rather brute force.
4858 Need to do some profiling. */
4860 for (i = 0; i < expr_hash_table_size; i++)
4861 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
4863 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
4864 we don't want to insert a copy here because the expression may not
4865 really be redundant. So only insert an insn if the expression was
4866 deleted. This test also avoids further processing if the
4867 expression wasn't deleted anywhere. */
4868 if (expr->reaching_reg == NULL)
4871 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4873 if (! occr->deleted_p)
4876 for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
4878 rtx insn = avail->insn;
4880 /* No need to handle this one if handled already. */
4881 if (avail->copied_p)
4884 /* Don't handle this one if it's a redundant one. */
4885 if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
4888 /* Or if the expression doesn't reach the deleted one. */
4889 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
4891 BLOCK_FOR_INSN (occr->insn)))
4894 /* Copy the result of avail to reaching_reg. */
4895 pre_insert_copy_insn (expr, insn);
4896 avail->copied_p = 1;
4902 /* Delete redundant computations.
4903 Deletion is done by changing the insn to copy the `reaching_reg' of
4904 the expression into the result of the SET. It is left to later passes
4905 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
4907 Returns non-zero if a change is made. */
4918 for (i = 0; i < expr_hash_table_size; i++)
4919 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
4921 int indx = expr->bitmap_index;
4923 /* We only need to search antic_occr since we require
4926 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4928 rtx insn = occr->insn;
4930 basic_block bb = BLOCK_FOR_INSN (insn);
4932 if (TEST_BIT (pre_delete_map[bb->index], indx))
4934 set = single_set (insn);
4938 /* Create a pseudo-reg to store the result of reaching
4939 expressions into. Get the mode for the new pseudo from
4940 the mode of the original destination pseudo. */
4941 if (expr->reaching_reg == NULL)
4943 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
4945 /* In theory this should never fail since we're creating
4948 However, on the x86 some of the movXX patterns actually
4949 contain clobbers of scratch regs. This may cause the
4950 insn created by validate_change to not match any pattern
4951 and thus cause validate_change to fail. */
4952 if (validate_change (insn, &SET_SRC (set),
4953 expr->reaching_reg, 0))
4955 occr->deleted_p = 1;
4956 SET_BIT (pre_redundant_insns, INSN_CUID (insn));
4964 "PRE: redundant insn %d (expression %d) in ",
4965 INSN_UID (insn), indx);
4966 fprintf (gcse_file, "bb %d, reaching reg is %d\n",
4967 bb->index, REGNO (expr->reaching_reg));
4976 /* Perform GCSE optimizations using PRE.
4977 This is called by one_pre_gcse_pass after all the dataflow analysis
4980 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
4981 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
4982 Compiler Design and Implementation.
4984 ??? A new pseudo reg is created to hold the reaching expression. The nice
4985 thing about the classical approach is that it would try to use an existing
4986 reg. If the register can't be adequately optimized [i.e. we introduce
4987 reload problems], one could add a pass here to propagate the new register
4990 ??? We don't handle single sets in PARALLELs because we're [currently] not
4991 able to copy the rest of the parallel when we insert copies to create full
4992 redundancies from partial redundancies. However, there's no reason why we
4993 can't handle PARALLELs in the cases where there are no partial
5000 int did_insert, changed;
5001 struct expr **index_map;
5004 /* Compute a mapping from expression number (`bitmap_index') to
5005 hash table entry. */
5007 index_map = (struct expr **) xcalloc (n_exprs, sizeof (struct expr *));
5008 for (i = 0; i < expr_hash_table_size; i++)
5009 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
5010 index_map[expr->bitmap_index] = expr;
5012 /* Reset bitmap used to track which insns are redundant. */
5013 pre_redundant_insns = sbitmap_alloc (max_cuid);
5014 sbitmap_zero (pre_redundant_insns);
5016 /* Delete the redundant insns first so that
5017 - we know what register to use for the new insns and for the other
5018 ones with reaching expressions
5019 - we know which insns are redundant when we go to create copies */
5021 changed = pre_delete ();
5023 did_insert = pre_edge_insert (edge_list, index_map);
5025 /* In other places with reaching expressions, copy the expression to the
5026 specially allocated pseudo-reg that reaches the redundant expr. */
5027 pre_insert_copies ();
5030 commit_edge_insertions ();
5035 free (pre_redundant_insns);
5039 /* Top level routine to perform one PRE GCSE pass.
5041 Return non-zero if a change was made. */
5044 one_pre_gcse_pass (pass)
5049 gcse_subst_count = 0;
5050 gcse_create_count = 0;
5052 alloc_expr_hash_table (max_cuid);
5053 add_noreturn_fake_exit_edges ();
5055 compute_ld_motion_mems ();
5057 compute_expr_hash_table ();
5058 trim_ld_motion_mems ();
5060 dump_hash_table (gcse_file, "Expression", expr_hash_table,
5061 expr_hash_table_size, n_exprs);
5065 alloc_pre_mem (n_basic_blocks, n_exprs);
5066 compute_pre_data ();
5067 changed |= pre_gcse ();
5068 free_edge_list (edge_list);
5073 remove_fake_edges ();
5074 free_expr_hash_table ();
5078 fprintf (gcse_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
5079 current_function_name, pass, bytes_used);
5080 fprintf (gcse_file, "%d substs, %d insns created\n",
5081 gcse_subst_count, gcse_create_count);
5087 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
5088 If notes are added to an insn which references a CODE_LABEL, the
5089 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
5090 because the following loop optimization pass requires them. */
5092 /* ??? This is very similar to the loop.c add_label_notes function. We
5093 could probably share code here. */
5095 /* ??? If there was a jump optimization pass after gcse and before loop,
5096 then we would not need to do this here, because jump would add the
5097 necessary REG_LABEL notes. */
5100 add_label_notes (x, insn)
5104 enum rtx_code code = GET_CODE (x);
5108 if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
5110 /* This code used to ignore labels that referred to dispatch tables to
5111 avoid flow generating (slighly) worse code.
5113 We no longer ignore such label references (see LABEL_REF handling in
5114 mark_jump_label for additional information). */
5116 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0),
5118 if (LABEL_P (XEXP (x, 0)))
5119 LABEL_NUSES (XEXP (x, 0))++;
5123 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
5126 add_label_notes (XEXP (x, i), insn);
5127 else if (fmt[i] == 'E')
5128 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5129 add_label_notes (XVECEXP (x, i, j), insn);
5133 /* Compute transparent outgoing information for each block.
5135 An expression is transparent to an edge unless it is killed by
5136 the edge itself. This can only happen with abnormal control flow,
5137 when the edge is traversed through a call. This happens with
5138 non-local labels and exceptions.
5140 This would not be necessary if we split the edge. While this is
5141 normally impossible for abnormal critical edges, with some effort
5142 it should be possible with exception handling, since we still have
5143 control over which handler should be invoked. But due to increased
5144 EH table sizes, this may not be worthwhile. */
5147 compute_transpout ()
5153 sbitmap_vector_ones (transpout, n_basic_blocks);
5155 for (bb = 0; bb < n_basic_blocks; ++bb)
5157 /* Note that flow inserted a nop a the end of basic blocks that
5158 end in call instructions for reasons other than abnormal
5160 if (GET_CODE (BLOCK_END (bb)) != CALL_INSN)
5163 for (i = 0; i < expr_hash_table_size; i++)
5164 for (expr = expr_hash_table[i]; expr ; expr = expr->next_same_hash)
5165 if (GET_CODE (expr->expr) == MEM)
5167 if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
5168 && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
5171 /* ??? Optimally, we would use interprocedural alias
5172 analysis to determine if this mem is actually killed
5174 RESET_BIT (transpout[bb], expr->bitmap_index);
5179 /* Removal of useless null pointer checks */
5181 /* Called via note_stores. X is set by SETTER. If X is a register we must
5182 invalidate nonnull_local and set nonnull_killed. DATA is really a
5183 `null_pointer_info *'.
5185 We ignore hard registers. */
5188 invalidate_nonnull_info (x, setter, data)
5190 rtx setter ATTRIBUTE_UNUSED;
5194 struct null_pointer_info *npi = (struct null_pointer_info *) data;
5196 while (GET_CODE (x) == SUBREG)
5199 /* Ignore anything that is not a register or is a hard register. */
5200 if (GET_CODE (x) != REG
5201 || REGNO (x) < npi->min_reg
5202 || REGNO (x) >= npi->max_reg)
5205 regno = REGNO (x) - npi->min_reg;
5207 RESET_BIT (npi->nonnull_local[npi->current_block], regno);
5208 SET_BIT (npi->nonnull_killed[npi->current_block], regno);
5211 /* Do null-pointer check elimination for the registers indicated in
5212 NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
5213 they are not our responsibility to free. */
5216 delete_null_pointer_checks_1 (delete_list, block_reg, nonnull_avin,
5218 varray_type *delete_list;
5219 unsigned int *block_reg;
5220 sbitmap *nonnull_avin;
5221 sbitmap *nonnull_avout;
5222 struct null_pointer_info *npi;
5226 sbitmap *nonnull_local = npi->nonnull_local;
5227 sbitmap *nonnull_killed = npi->nonnull_killed;
5229 /* Compute local properties, nonnull and killed. A register will have
5230 the nonnull property if at the end of the current block its value is
5231 known to be nonnull. The killed property indicates that somewhere in
5232 the block any information we had about the register is killed.
5234 Note that a register can have both properties in a single block. That
5235 indicates that it's killed, then later in the block a new value is
5237 sbitmap_vector_zero (nonnull_local, n_basic_blocks);
5238 sbitmap_vector_zero (nonnull_killed, n_basic_blocks);
5240 for (current_block = 0; current_block < n_basic_blocks; current_block++)
5242 rtx insn, stop_insn;
5244 /* Set the current block for invalidate_nonnull_info. */
5245 npi->current_block = current_block;
5247 /* Scan each insn in the basic block looking for memory references and
5249 stop_insn = NEXT_INSN (BLOCK_END (current_block));
5250 for (insn = BLOCK_HEAD (current_block);
5252 insn = NEXT_INSN (insn))
5257 /* Ignore anything that is not a normal insn. */
5258 if (! INSN_P (insn))
5261 /* Basically ignore anything that is not a simple SET. We do have
5262 to make sure to invalidate nonnull_local and set nonnull_killed
5263 for such insns though. */
5264 set = single_set (insn);
5267 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5271 /* See if we've got a useable memory load. We handle it first
5272 in case it uses its address register as a dest (which kills
5273 the nonnull property). */
5274 if (GET_CODE (SET_SRC (set)) == MEM
5275 && GET_CODE ((reg = XEXP (SET_SRC (set), 0))) == REG
5276 && REGNO (reg) >= npi->min_reg
5277 && REGNO (reg) < npi->max_reg)
5278 SET_BIT (nonnull_local[current_block],
5279 REGNO (reg) - npi->min_reg);
5281 /* Now invalidate stuff clobbered by this insn. */
5282 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5284 /* And handle stores, we do these last since any sets in INSN can
5285 not kill the nonnull property if it is derived from a MEM
5286 appearing in a SET_DEST. */
5287 if (GET_CODE (SET_DEST (set)) == MEM
5288 && GET_CODE ((reg = XEXP (SET_DEST (set), 0))) == REG
5289 && REGNO (reg) >= npi->min_reg
5290 && REGNO (reg) < npi->max_reg)
5291 SET_BIT (nonnull_local[current_block],
5292 REGNO (reg) - npi->min_reg);
5296 /* Now compute global properties based on the local properties. This
5297 is a classic global availablity algorithm. */
5298 compute_available (nonnull_local, nonnull_killed,
5299 nonnull_avout, nonnull_avin);
5301 /* Now look at each bb and see if it ends with a compare of a value
5303 for (bb = 0; bb < n_basic_blocks; bb++)
5305 rtx last_insn = BLOCK_END (bb);
5306 rtx condition, earliest;
5307 int compare_and_branch;
5309 /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
5310 since BLOCK_REG[BB] is zero if this block did not end with a
5311 comparison against zero, this condition works. */
5312 if (block_reg[bb] < npi->min_reg
5313 || block_reg[bb] >= npi->max_reg)
5316 /* LAST_INSN is a conditional jump. Get its condition. */
5317 condition = get_condition (last_insn, &earliest);
5319 /* If we can't determine the condition then skip. */
5323 /* Is the register known to have a nonzero value? */
5324 if (!TEST_BIT (nonnull_avout[bb], block_reg[bb] - npi->min_reg))
5327 /* Try to compute whether the compare/branch at the loop end is one or
5328 two instructions. */
5329 if (earliest == last_insn)
5330 compare_and_branch = 1;
5331 else if (earliest == prev_nonnote_insn (last_insn))
5332 compare_and_branch = 2;
5336 /* We know the register in this comparison is nonnull at exit from
5337 this block. We can optimize this comparison. */
5338 if (GET_CODE (condition) == NE)
5342 new_jump = emit_jump_insn_before (gen_jump (JUMP_LABEL (last_insn)),
5344 JUMP_LABEL (new_jump) = JUMP_LABEL (last_insn);
5345 LABEL_NUSES (JUMP_LABEL (new_jump))++;
5346 emit_barrier_after (new_jump);
5349 VARRAY_RTX_INIT (*delete_list, 10, "delete_list");
5351 VARRAY_PUSH_RTX (*delete_list, last_insn);
5352 if (compare_and_branch == 2)
5353 VARRAY_PUSH_RTX (*delete_list, earliest);
5355 /* Don't check this block again. (Note that BLOCK_END is
5356 invalid here; we deleted the last instruction in the
5362 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
5365 This is conceptually similar to global constant/copy propagation and
5366 classic global CSE (it even uses the same dataflow equations as cprop).
5368 If a register is used as memory address with the form (mem (reg)), then we
5369 know that REG can not be zero at that point in the program. Any instruction
5370 which sets REG "kills" this property.
5372 So, if every path leading to a conditional branch has an available memory
5373 reference of that form, then we know the register can not have the value
5374 zero at the conditional branch.
5376 So we merely need to compute the local properies and propagate that data
5377 around the cfg, then optimize where possible.
5379 We run this pass two times. Once before CSE, then again after CSE. This
5380 has proven to be the most profitable approach. It is rare for new
5381 optimization opportunities of this nature to appear after the first CSE
5384 This could probably be integrated with global cprop with a little work. */
5387 delete_null_pointer_checks (f)
5388 rtx f ATTRIBUTE_UNUSED;
5390 sbitmap *nonnull_avin, *nonnull_avout;
5391 unsigned int *block_reg;
5392 varray_type delete_list = NULL;
5398 struct null_pointer_info npi;
5400 /* If we have only a single block, then there's nothing to do. */
5401 if (n_basic_blocks <= 1)
5404 /* Trying to perform global optimizations on flow graphs which have
5405 a high connectivity will take a long time and is unlikely to be
5406 particularly useful.
5408 In normal circumstances a cfg should have about twice as many edges
5409 as blocks. But we do not want to punish small functions which have
5410 a couple switch statements. So we require a relatively large number
5411 of basic blocks and the ratio of edges to blocks to be high. */
5412 if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
5415 /* We need four bitmaps, each with a bit for each register in each
5417 max_reg = max_reg_num ();
5418 regs_per_pass = get_bitmap_width (4, n_basic_blocks, max_reg);
5420 /* Allocate bitmaps to hold local and global properties. */
5421 npi.nonnull_local = sbitmap_vector_alloc (n_basic_blocks, regs_per_pass);
5422 npi.nonnull_killed = sbitmap_vector_alloc (n_basic_blocks, regs_per_pass);
5423 nonnull_avin = sbitmap_vector_alloc (n_basic_blocks, regs_per_pass);
5424 nonnull_avout = sbitmap_vector_alloc (n_basic_blocks, regs_per_pass);
5426 /* Go through the basic blocks, seeing whether or not each block
5427 ends with a conditional branch whose condition is a comparison
5428 against zero. Record the register compared in BLOCK_REG. */
5429 block_reg = (unsigned int *) xcalloc (n_basic_blocks, sizeof (int));
5430 for (bb = 0; bb < n_basic_blocks; bb++)
5432 rtx last_insn = BLOCK_END (bb);
5433 rtx condition, earliest, reg;
5435 /* We only want conditional branches. */
5436 if (GET_CODE (last_insn) != JUMP_INSN
5437 || !any_condjump_p (last_insn)
5438 || !onlyjump_p (last_insn))
5441 /* LAST_INSN is a conditional jump. Get its condition. */
5442 condition = get_condition (last_insn, &earliest);
5444 /* If we were unable to get the condition, or it is not a equality
5445 comparison against zero then there's nothing we can do. */
5447 || (GET_CODE (condition) != NE && GET_CODE (condition) != EQ)
5448 || GET_CODE (XEXP (condition, 1)) != CONST_INT
5449 || (XEXP (condition, 1)
5450 != CONST0_RTX (GET_MODE (XEXP (condition, 0)))))
5453 /* We must be checking a register against zero. */
5454 reg = XEXP (condition, 0);
5455 if (GET_CODE (reg) != REG)
5458 block_reg[bb] = REGNO (reg);
5461 /* Go through the algorithm for each block of registers. */
5462 for (reg = FIRST_PSEUDO_REGISTER; reg < max_reg; reg += regs_per_pass)
5465 npi.max_reg = MIN (reg + regs_per_pass, max_reg);
5466 delete_null_pointer_checks_1 (&delete_list, block_reg, nonnull_avin,
5467 nonnull_avout, &npi);
5470 /* Now delete the instructions all at once. This breaks the CFG. */
5473 for (i = 0; i < VARRAY_ACTIVE_SIZE (delete_list); i++)
5474 delete_insn (VARRAY_RTX (delete_list, i));
5475 VARRAY_FREE (delete_list);
5478 /* Free the table of registers compared at the end of every block. */
5482 sbitmap_vector_free (npi.nonnull_local);
5483 sbitmap_vector_free (npi.nonnull_killed);
5484 sbitmap_vector_free (nonnull_avin);
5485 sbitmap_vector_free (nonnull_avout);
5488 /* Code Hoisting variables and subroutines. */
5490 /* Very busy expressions. */
5491 static sbitmap *hoist_vbein;
5492 static sbitmap *hoist_vbeout;
5494 /* Hoistable expressions. */
5495 static sbitmap *hoist_exprs;
5497 /* Dominator bitmaps. */
5498 static sbitmap *dominators;
5500 /* ??? We could compute post dominators and run this algorithm in
5501 reverse to to perform tail merging, doing so would probably be
5502 more effective than the tail merging code in jump.c.
5504 It's unclear if tail merging could be run in parallel with
5505 code hoisting. It would be nice. */
5507 /* Allocate vars used for code hoisting analysis. */
5510 alloc_code_hoist_mem (n_blocks, n_exprs)
5511 int n_blocks, n_exprs;
5513 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
5514 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
5515 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
5517 hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
5518 hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
5519 hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
5520 transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
5522 dominators = sbitmap_vector_alloc (n_blocks, n_blocks);
5525 /* Free vars used for code hoisting analysis. */
5528 free_code_hoist_mem ()
5530 sbitmap_vector_free (antloc);
5531 sbitmap_vector_free (transp);
5532 sbitmap_vector_free (comp);
5534 sbitmap_vector_free (hoist_vbein);
5535 sbitmap_vector_free (hoist_vbeout);
5536 sbitmap_vector_free (hoist_exprs);
5537 sbitmap_vector_free (transpout);
5539 sbitmap_vector_free (dominators);
5542 /* Compute the very busy expressions at entry/exit from each block.
5544 An expression is very busy if all paths from a given point
5545 compute the expression. */
5548 compute_code_hoist_vbeinout ()
5550 int bb, changed, passes;
5552 sbitmap_vector_zero (hoist_vbeout, n_basic_blocks);
5553 sbitmap_vector_zero (hoist_vbein, n_basic_blocks);
5562 /* We scan the blocks in the reverse order to speed up
5564 for (bb = n_basic_blocks - 1; bb >= 0; bb--)
5566 changed |= sbitmap_a_or_b_and_c (hoist_vbein[bb], antloc[bb],
5567 hoist_vbeout[bb], transp[bb]);
5568 if (bb != n_basic_blocks - 1)
5569 sbitmap_intersection_of_succs (hoist_vbeout[bb], hoist_vbein, bb);
5576 fprintf (gcse_file, "hoisting vbeinout computation: %d passes\n", passes);
5579 /* Top level routine to do the dataflow analysis needed by code hoisting. */
5582 compute_code_hoist_data ()
5584 compute_local_properties (transp, comp, antloc, 0);
5585 compute_transpout ();
5586 compute_code_hoist_vbeinout ();
5587 calculate_dominance_info (NULL, dominators, CDI_DOMINATORS);
5589 fprintf (gcse_file, "\n");
5592 /* Determine if the expression identified by EXPR_INDEX would
5593 reach BB unimpared if it was placed at the end of EXPR_BB.
5595 It's unclear exactly what Muchnick meant by "unimpared". It seems
5596 to me that the expression must either be computed or transparent in
5597 *every* block in the path(s) from EXPR_BB to BB. Any other definition
5598 would allow the expression to be hoisted out of loops, even if
5599 the expression wasn't a loop invariant.
5601 Contrast this to reachability for PRE where an expression is
5602 considered reachable if *any* path reaches instead of *all*
5606 hoist_expr_reaches_here_p (expr_bb, expr_index, bb, visited)
5607 basic_block expr_bb;
5613 int visited_allocated_locally = 0;
5616 if (visited == NULL)
5618 visited_allocated_locally = 1;
5619 visited = xcalloc (n_basic_blocks, 1);
5622 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
5624 basic_block pred_bb = pred->src;
5626 if (pred->src == ENTRY_BLOCK_PTR)
5628 else if (visited[pred_bb->index])
5631 /* Does this predecessor generate this expression? */
5632 else if (TEST_BIT (comp[pred_bb->index], expr_index))
5634 else if (! TEST_BIT (transp[pred_bb->index], expr_index))
5640 visited[pred_bb->index] = 1;
5641 if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
5646 if (visited_allocated_locally)
5649 return (pred == NULL);
5652 /* Actually perform code hoisting. */
5659 struct expr **index_map;
5662 sbitmap_vector_zero (hoist_exprs, n_basic_blocks);
5664 /* Compute a mapping from expression number (`bitmap_index') to
5665 hash table entry. */
5667 index_map = (struct expr **) xcalloc (n_exprs, sizeof (struct expr *));
5668 for (i = 0; i < expr_hash_table_size; i++)
5669 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
5670 index_map[expr->bitmap_index] = expr;
5672 /* Walk over each basic block looking for potentially hoistable
5673 expressions, nothing gets hoisted from the entry block. */
5674 for (bb = 0; bb < n_basic_blocks; bb++)
5677 int insn_inserted_p;
5679 /* Examine each expression that is very busy at the exit of this
5680 block. These are the potentially hoistable expressions. */
5681 for (i = 0; i < hoist_vbeout[bb]->n_bits; i++)
5685 if (TEST_BIT (hoist_vbeout[bb], i) && TEST_BIT (transpout[bb], i))
5687 /* We've found a potentially hoistable expression, now
5688 we look at every block BB dominates to see if it
5689 computes the expression. */
5690 for (dominated = 0; dominated < n_basic_blocks; dominated++)
5692 /* Ignore self dominance. */
5694 || ! TEST_BIT (dominators[dominated], bb))
5697 /* We've found a dominated block, now see if it computes
5698 the busy expression and whether or not moving that
5699 expression to the "beginning" of that block is safe. */
5700 if (!TEST_BIT (antloc[dominated], i))
5703 /* Note if the expression would reach the dominated block
5704 unimpared if it was placed at the end of BB.
5706 Keep track of how many times this expression is hoistable
5707 from a dominated block into BB. */
5708 if (hoist_expr_reaches_here_p (BASIC_BLOCK (bb), i,
5709 BASIC_BLOCK (dominated), NULL))
5713 /* If we found more than one hoistable occurence of this
5714 expression, then note it in the bitmap of expressions to
5715 hoist. It makes no sense to hoist things which are computed
5716 in only one BB, and doing so tends to pessimize register
5717 allocation. One could increase this value to try harder
5718 to avoid any possible code expansion due to register
5719 allocation issues; however experiments have shown that
5720 the vast majority of hoistable expressions are only movable
5721 from two successors, so raising this threshhold is likely
5722 to nullify any benefit we get from code hoisting. */
5725 SET_BIT (hoist_exprs[bb], i);
5731 /* If we found nothing to hoist, then quit now. */
5735 /* Loop over all the hoistable expressions. */
5736 for (i = 0; i < hoist_exprs[bb]->n_bits; i++)
5738 /* We want to insert the expression into BB only once, so
5739 note when we've inserted it. */
5740 insn_inserted_p = 0;
5742 /* These tests should be the same as the tests above. */
5743 if (TEST_BIT (hoist_vbeout[bb], i))
5745 /* We've found a potentially hoistable expression, now
5746 we look at every block BB dominates to see if it
5747 computes the expression. */
5748 for (dominated = 0; dominated < n_basic_blocks; dominated++)
5750 /* Ignore self dominance. */
5752 || ! TEST_BIT (dominators[dominated], bb))
5755 /* We've found a dominated block, now see if it computes
5756 the busy expression and whether or not moving that
5757 expression to the "beginning" of that block is safe. */
5758 if (!TEST_BIT (antloc[dominated], i))
5761 /* The expression is computed in the dominated block and
5762 it would be safe to compute it at the start of the
5763 dominated block. Now we have to determine if the
5764 expresion would reach the dominated block if it was
5765 placed at the end of BB. */
5766 if (hoist_expr_reaches_here_p (BASIC_BLOCK (bb), i,
5767 BASIC_BLOCK (dominated), NULL))
5769 struct expr *expr = index_map[i];
5770 struct occr *occr = expr->antic_occr;
5774 /* Find the right occurence of this expression. */
5775 while (BLOCK_NUM (occr->insn) != dominated && occr)
5778 /* Should never happen. */
5784 set = single_set (insn);
5788 /* Create a pseudo-reg to store the result of reaching
5789 expressions into. Get the mode for the new pseudo
5790 from the mode of the original destination pseudo. */
5791 if (expr->reaching_reg == NULL)
5793 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
5795 /* In theory this should never fail since we're creating
5798 However, on the x86 some of the movXX patterns
5799 actually contain clobbers of scratch regs. This may
5800 cause the insn created by validate_change to not
5801 match any pattern and thus cause validate_change to
5803 if (validate_change (insn, &SET_SRC (set),
5804 expr->reaching_reg, 0))
5806 occr->deleted_p = 1;
5807 if (!insn_inserted_p)
5809 insert_insn_end_bb (index_map[i],
5810 BASIC_BLOCK (bb), 0);
5811 insn_inserted_p = 1;
5823 /* Top level routine to perform one code hoisting (aka unification) pass
5825 Return non-zero if a change was made. */
5828 one_code_hoisting_pass ()
5832 alloc_expr_hash_table (max_cuid);
5833 compute_expr_hash_table ();
5835 dump_hash_table (gcse_file, "Code Hosting Expressions", expr_hash_table,
5836 expr_hash_table_size, n_exprs);
5840 alloc_code_hoist_mem (n_basic_blocks, n_exprs);
5841 compute_code_hoist_data ();
5843 free_code_hoist_mem ();
5846 free_expr_hash_table ();
5851 /* Here we provide the things required to do store motion towards
5852 the exit. In order for this to be effective, gcse also needed to
5853 be taught how to move a load when it is kill only by a store to itself.
5858 void foo(float scale)
5860 for (i=0; i<10; i++)
5864 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
5865 the load out since its live around the loop, and stored at the bottom
5868 The 'Load Motion' referred to and implemented in this file is
5869 an enhancement to gcse which when using edge based lcm, recognizes
5870 this situation and allows gcse to move the load out of the loop.
5872 Once gcse has hoisted the load, store motion can then push this
5873 load towards the exit, and we end up with no loads or stores of 'i'
5876 /* This will search the ldst list for a matching expresion. If it
5877 doesn't find one, we create one and initialize it. */
5879 static struct ls_expr *
5883 struct ls_expr * ptr;
5885 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
5886 if (expr_equiv_p (ptr->pattern, x))
5891 ptr = (struct ls_expr *) xmalloc (sizeof (struct ls_expr));
5893 ptr->next = pre_ldst_mems;
5896 ptr->loads = NULL_RTX;
5897 ptr->stores = NULL_RTX;
5898 ptr->reaching_reg = NULL_RTX;
5901 ptr->hash_index = 0;
5902 pre_ldst_mems = ptr;
5908 /* Free up an individual ldst entry. */
5911 free_ldst_entry (ptr)
5912 struct ls_expr * ptr;
5914 free_INSN_LIST_list (& ptr->loads);
5915 free_INSN_LIST_list (& ptr->stores);
5920 /* Free up all memory associated with the ldst list. */
5925 while (pre_ldst_mems)
5927 struct ls_expr * tmp = pre_ldst_mems;
5929 pre_ldst_mems = pre_ldst_mems->next;
5931 free_ldst_entry (tmp);
5934 pre_ldst_mems = NULL;
5937 /* Dump debugging info about the ldst list. */
5940 print_ldst_list (file)
5943 struct ls_expr * ptr;
5945 fprintf (file, "LDST list: \n");
5947 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
5949 fprintf (file, " Pattern (%3d): ", ptr->index);
5951 print_rtl (file, ptr->pattern);
5953 fprintf (file, "\n Loads : ");
5956 print_rtl (file, ptr->loads);
5958 fprintf (file, "(nil)");
5960 fprintf (file, "\n Stores : ");
5963 print_rtl (file, ptr->stores);
5965 fprintf (file, "(nil)");
5967 fprintf (file, "\n\n");
5970 fprintf (file, "\n");
5973 /* Returns 1 if X is in the list of ldst only expressions. */
5975 static struct ls_expr *
5976 find_rtx_in_ldst (x)
5979 struct ls_expr * ptr;
5981 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
5982 if (expr_equiv_p (ptr->pattern, x) && ! ptr->invalid)
5988 /* Assign each element of the list of mems a monotonically increasing value. */
5993 struct ls_expr * ptr;
5996 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6002 /* Return first item in the list. */
6004 static inline struct ls_expr *
6007 return pre_ldst_mems;
6010 /* Return the next item in ther list after the specified one. */
6012 static inline struct ls_expr *
6014 struct ls_expr * ptr;
6019 /* Load Motion for loads which only kill themselves. */
6021 /* Return true if x is a simple MEM operation, with no registers or
6022 side effects. These are the types of loads we consider for the
6023 ld_motion list, otherwise we let the usual aliasing take care of it. */
6029 if (GET_CODE (x) != MEM)
6032 if (MEM_VOLATILE_P (x))
6035 if (GET_MODE (x) == BLKmode)
6038 if (!rtx_varies_p (XEXP (x, 0), 0))
6044 /* Make sure there isn't a buried reference in this pattern anywhere.
6045 If there is, invalidate the entry for it since we're not capable
6046 of fixing it up just yet.. We have to be sure we know about ALL
6047 loads since the aliasing code will allow all entries in the
6048 ld_motion list to not-alias itself. If we miss a load, we will get
6049 the wrong value since gcse might common it and we won't know to
6053 invalidate_any_buried_refs (x)
6058 struct ls_expr * ptr;
6060 /* Invalidate it in the list. */
6061 if (GET_CODE (x) == MEM && simple_mem (x))
6063 ptr = ldst_entry (x);
6067 /* Recursively process the insn. */
6068 fmt = GET_RTX_FORMAT (GET_CODE (x));
6070 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
6073 invalidate_any_buried_refs (XEXP (x, i));
6074 else if (fmt[i] == 'E')
6075 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6076 invalidate_any_buried_refs (XVECEXP (x, i, j));
6080 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
6081 being defined as MEM loads and stores to symbols, with no
6082 side effects and no registers in the expression. If there are any
6083 uses/defs which dont match this criteria, it is invalidated and
6084 trimmed out later. */
6087 compute_ld_motion_mems ()
6089 struct ls_expr * ptr;
6093 pre_ldst_mems = NULL;
6095 for (bb = 0; bb < n_basic_blocks; bb++)
6097 for (insn = BLOCK_HEAD (bb);
6098 insn && insn != NEXT_INSN (BLOCK_END (bb));
6099 insn = NEXT_INSN (insn))
6101 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
6103 if (GET_CODE (PATTERN (insn)) == SET)
6105 rtx src = SET_SRC (PATTERN (insn));
6106 rtx dest = SET_DEST (PATTERN (insn));
6108 /* Check for a simple LOAD... */
6109 if (GET_CODE (src) == MEM && simple_mem (src))
6111 ptr = ldst_entry (src);
6112 if (GET_CODE (dest) == REG)
6113 ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
6119 /* Make sure there isn't a buried load somewhere. */
6120 invalidate_any_buried_refs (src);
6123 /* Check for stores. Don't worry about aliased ones, they
6124 will block any movement we might do later. We only care
6125 about this exact pattern since those are the only
6126 circumstance that we will ignore the aliasing info. */
6127 if (GET_CODE (dest) == MEM && simple_mem (dest))
6129 ptr = ldst_entry (dest);
6131 if (GET_CODE (src) != MEM
6132 && GET_CODE (src) != ASM_OPERANDS)
6133 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
6139 invalidate_any_buried_refs (PATTERN (insn));
6145 /* Remove any references that have been either invalidated or are not in the
6146 expression list for pre gcse. */
6149 trim_ld_motion_mems ()
6151 struct ls_expr * last = NULL;
6152 struct ls_expr * ptr = first_ls_expr ();
6156 int del = ptr->invalid;
6157 struct expr * expr = NULL;
6159 /* Delete if entry has been made invalid. */
6165 /* Delete if we cannot find this mem in the expression list. */
6166 for (i = 0; i < expr_hash_table_size && del; i++)
6168 for (expr = expr_hash_table[i];
6170 expr = expr->next_same_hash)
6171 if (expr_equiv_p (expr->expr, ptr->pattern))
6183 last->next = ptr->next;
6184 free_ldst_entry (ptr);
6189 pre_ldst_mems = pre_ldst_mems->next;
6190 free_ldst_entry (ptr);
6191 ptr = pre_ldst_mems;
6196 /* Set the expression field if we are keeping it. */
6203 /* Show the world what we've found. */
6204 if (gcse_file && pre_ldst_mems != NULL)
6205 print_ldst_list (gcse_file);
6208 /* This routine will take an expression which we are replacing with
6209 a reaching register, and update any stores that are needed if
6210 that expression is in the ld_motion list. Stores are updated by
6211 copying their SRC to the reaching register, and then storeing
6212 the reaching register into the store location. These keeps the
6213 correct value in the reaching register for the loads. */
6216 update_ld_motion_stores (expr)
6219 struct ls_expr * mem_ptr;
6221 if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
6223 /* We can try to find just the REACHED stores, but is shouldn't
6224 matter to set the reaching reg everywhere... some might be
6225 dead and should be eliminated later. */
6227 /* We replace SET mem = expr with
6229 SET mem = reg , where reg is the
6230 reaching reg used in the load. */
6231 rtx list = mem_ptr->stores;
6233 for ( ; list != NULL_RTX; list = XEXP (list, 1))
6235 rtx insn = XEXP (list, 0);
6236 rtx pat = PATTERN (insn);
6237 rtx src = SET_SRC (pat);
6238 rtx reg = expr->reaching_reg;
6241 /* If we've already copied it, continue. */
6242 if (expr->reaching_reg == src)
6247 fprintf (gcse_file, "PRE: store updated with reaching reg ");
6248 print_rtl (gcse_file, expr->reaching_reg);
6249 fprintf (gcse_file, ":\n ");
6250 print_inline_rtx (gcse_file, insn, 8);
6251 fprintf (gcse_file, "\n");
6254 copy = gen_move_insn ( reg, SET_SRC (pat));
6255 new = emit_insn_before (copy, insn);
6256 record_one_set (REGNO (reg), new);
6257 set_block_for_new_insns (new, BLOCK_FOR_INSN (insn));
6258 SET_SRC (pat) = reg;
6260 /* un-recognize this pattern since it's probably different now. */
6261 INSN_CODE (insn) = -1;
6262 gcse_create_count++;
6267 /* Store motion code. */
6269 /* This is used to communicate the target bitvector we want to use in the
6270 reg_set_info routine when called via the note_stores mechanism. */
6271 static sbitmap * regvec;
6273 /* Used in computing the reverse edge graph bit vectors. */
6274 static sbitmap * st_antloc;
6276 /* Global holding the number of store expressions we are dealing with. */
6277 static int num_stores;
6279 /* Checks to set if we need to mark a register set. Called from note_stores. */
6282 reg_set_info (dest, setter, data)
6283 rtx dest, setter ATTRIBUTE_UNUSED;
6284 void * data ATTRIBUTE_UNUSED;
6286 if (GET_CODE (dest) == SUBREG)
6287 dest = SUBREG_REG (dest);
6289 if (GET_CODE (dest) == REG)
6290 SET_BIT (*regvec, REGNO (dest));
6293 /* Return non-zero if the register operands of expression X are killed
6294 anywhere in basic block BB. */
6297 store_ops_ok (x, bb)
6305 /* Repeat is used to turn tail-recursion into iteration. */
6311 code = GET_CODE (x);
6315 /* If a reg has changed after us in this
6316 block, the operand has been killed. */
6317 return TEST_BIT (reg_set_in_block[bb->index], REGNO (x));
6344 i = GET_RTX_LENGTH (code) - 1;
6345 fmt = GET_RTX_FORMAT (code);
6351 rtx tem = XEXP (x, i);
6353 /* If we are about to do the last recursive call
6354 needed at this level, change it into iteration.
6355 This function is called enough to be worth it. */
6362 if (! store_ops_ok (tem, bb))
6365 else if (fmt[i] == 'E')
6369 for (j = 0; j < XVECLEN (x, i); j++)
6371 if (! store_ops_ok (XVECEXP (x, i, j), bb))
6380 /* Determine whether insn is MEM store pattern that we will consider moving. */
6383 find_moveable_store (insn)
6386 struct ls_expr * ptr;
6387 rtx dest = PATTERN (insn);
6389 if (GET_CODE (dest) != SET
6390 || GET_CODE (SET_SRC (dest)) == ASM_OPERANDS)
6393 dest = SET_DEST (dest);
6395 if (GET_CODE (dest) != MEM || MEM_VOLATILE_P (dest)
6396 || GET_MODE (dest) == BLKmode)
6399 if (GET_CODE (XEXP (dest, 0)) != SYMBOL_REF)
6402 if (rtx_varies_p (XEXP (dest, 0), 0))
6405 ptr = ldst_entry (dest);
6406 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
6409 /* Perform store motion. Much like gcse, except we move expressions the
6410 other way by looking at the flowgraph in reverse. */
6413 compute_store_table ()
6419 max_gcse_regno = max_reg_num ();
6421 reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks,
6423 sbitmap_vector_zero (reg_set_in_block, n_basic_blocks);
6426 /* Find all the stores we care about. */
6427 for (bb = 0; bb < n_basic_blocks; bb++)
6429 regvec = & (reg_set_in_block[bb]);
6430 for (insn = BLOCK_END (bb);
6431 insn && insn != PREV_INSN (BLOCK_HEAD (bb));
6432 insn = PREV_INSN (insn))
6434 /* Ignore anything that is not a normal insn. */
6435 if (! INSN_P (insn))
6438 if (GET_CODE (insn) == CALL_INSN)
6440 bool clobbers_all = false;
6441 #ifdef NON_SAVING_SETJMP
6442 if (NON_SAVING_SETJMP
6443 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
6444 clobbers_all = true;
6447 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
6449 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
6450 SET_BIT (reg_set_in_block[bb], regno);
6453 pat = PATTERN (insn);
6454 note_stores (pat, reg_set_info, NULL);
6456 /* Now that we've marked regs, look for stores. */
6457 if (GET_CODE (pat) == SET)
6458 find_moveable_store (insn);
6462 ret = enumerate_ldsts ();
6466 fprintf (gcse_file, "Store Motion Expressions.\n");
6467 print_ldst_list (gcse_file);
6473 /* Check to see if the load X is aliased with STORE_PATTERN. */
6476 load_kills_store (x, store_pattern)
6477 rtx x, store_pattern;
6479 if (true_dependence (x, GET_MODE (x), store_pattern, rtx_addr_varies_p))
6484 /* Go through the entire insn X, looking for any loads which might alias
6485 STORE_PATTERN. Return 1 if found. */
6488 find_loads (x, store_pattern)
6489 rtx x, store_pattern;
6498 if (GET_CODE (x) == SET)
6501 if (GET_CODE (x) == MEM)
6503 if (load_kills_store (x, store_pattern))
6507 /* Recursively process the insn. */
6508 fmt = GET_RTX_FORMAT (GET_CODE (x));
6510 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
6513 ret |= find_loads (XEXP (x, i), store_pattern);
6514 else if (fmt[i] == 'E')
6515 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6516 ret |= find_loads (XVECEXP (x, i, j), store_pattern);
6521 /* Check if INSN kills the store pattern X (is aliased with it).
6522 Return 1 if it it does. */
6525 store_killed_in_insn (x, insn)
6528 if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
6531 if (GET_CODE (insn) == CALL_INSN)
6533 if (CONST_OR_PURE_CALL_P (insn))
6539 if (GET_CODE (PATTERN (insn)) == SET)
6541 rtx pat = PATTERN (insn);
6542 /* Check for memory stores to aliased objects. */
6543 if (GET_CODE (SET_DEST (pat)) == MEM && !expr_equiv_p (SET_DEST (pat), x))
6544 /* pretend its a load and check for aliasing. */
6545 if (find_loads (SET_DEST (pat), x))
6547 return find_loads (SET_SRC (pat), x);
6550 return find_loads (PATTERN (insn), x);
6553 /* Returns 1 if the expression X is loaded or clobbered on or after INSN
6554 within basic block BB. */
6557 store_killed_after (x, insn, bb)
6566 /* Check if the register operands of the store are OK in this block.
6567 Note that if registers are changed ANYWHERE in the block, we'll
6568 decide we can't move it, regardless of whether it changed above
6569 or below the store. This could be improved by checking the register
6570 operands while lookinng for aliasing in each insn. */
6571 if (!store_ops_ok (XEXP (x, 0), bb))
6574 for ( ; insn && insn != NEXT_INSN (last); insn = NEXT_INSN (insn))
6575 if (store_killed_in_insn (x, insn))
6581 /* Returns 1 if the expression X is loaded or clobbered on or before INSN
6582 within basic block BB. */
6584 store_killed_before (x, insn, bb)
6588 rtx first = bb->head;
6591 return store_killed_in_insn (x, insn);
6593 /* Check if the register operands of the store are OK in this block.
6594 Note that if registers are changed ANYWHERE in the block, we'll
6595 decide we can't move it, regardless of whether it changed above
6596 or below the store. This could be improved by checking the register
6597 operands while lookinng for aliasing in each insn. */
6598 if (!store_ops_ok (XEXP (x, 0), bb))
6601 for ( ; insn && insn != PREV_INSN (first); insn = PREV_INSN (insn))
6602 if (store_killed_in_insn (x, insn))
6608 #define ANTIC_STORE_LIST(x) ((x)->loads)
6609 #define AVAIL_STORE_LIST(x) ((x)->stores)
6611 /* Given the table of available store insns at the end of blocks,
6612 determine which ones are not killed by aliasing, and generate
6613 the appropriate vectors for gen and killed. */
6615 build_store_vectors ()
6620 struct ls_expr * ptr;
6622 /* Build the gen_vector. This is any store in the table which is not killed
6623 by aliasing later in its block. */
6624 ae_gen = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks, num_stores);
6625 sbitmap_vector_zero (ae_gen, n_basic_blocks);
6627 st_antloc = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks, num_stores);
6628 sbitmap_vector_zero (st_antloc, n_basic_blocks);
6630 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6632 /* Put all the stores into either the antic list, or the avail list,
6634 rtx store_list = ptr->stores;
6635 ptr->stores = NULL_RTX;
6637 for (st = store_list; st != NULL; st = XEXP (st, 1))
6639 insn = XEXP (st, 0);
6640 bb = BLOCK_FOR_INSN (insn);
6642 if (!store_killed_after (ptr->pattern, insn, bb))
6644 /* If we've already seen an availale expression in this block,
6645 we can delete the one we saw already (It occurs earlier in
6646 the block), and replace it with this one). We'll copy the
6647 old SRC expression to an unused register in case there
6648 are any side effects. */
6649 if (TEST_BIT (ae_gen[bb->index], ptr->index))
6651 /* Find previous store. */
6653 for (st = AVAIL_STORE_LIST (ptr); st ; st = XEXP (st, 1))
6654 if (BLOCK_FOR_INSN (XEXP (st, 0)) == bb)
6658 rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
6660 fprintf(gcse_file, "Removing redundant store:\n");
6661 replace_store_insn (r, XEXP (st, 0), bb);
6662 XEXP (st, 0) = insn;
6666 SET_BIT (ae_gen[bb->index], ptr->index);
6667 AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn,
6668 AVAIL_STORE_LIST (ptr));
6671 if (!store_killed_before (ptr->pattern, insn, bb))
6673 SET_BIT (st_antloc[BLOCK_NUM (insn)], ptr->index);
6674 ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (insn,
6675 ANTIC_STORE_LIST (ptr));
6679 /* Free the original list of store insns. */
6680 free_INSN_LIST_list (&store_list);
6683 ae_kill = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks, num_stores);
6684 sbitmap_vector_zero (ae_kill, n_basic_blocks);
6686 transp = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks, num_stores);
6687 sbitmap_vector_zero (transp, n_basic_blocks);
6689 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6690 for (b = 0; b < n_basic_blocks; b++)
6692 if (store_killed_after (ptr->pattern, BLOCK_HEAD (b), BASIC_BLOCK (b)))
6694 /* The anticipatable expression is not killed if it's gen'd. */
6696 We leave this check out for now. If we have a code sequence
6697 in a block which looks like:
6701 We should flag this as having an ANTIC expression, NOT
6702 transparent, NOT killed, and AVAIL.
6703 Unfortunately, since we haven't re-written all loads to
6704 use the reaching reg, we'll end up doing an incorrect
6705 Load in the middle here if we push the store down. It happens in
6706 gcc.c-torture/execute/960311-1.c with -O3
6707 If we always kill it in this case, we'll sometimes do
6708 uneccessary work, but it shouldn't actually hurt anything.
6709 if (!TEST_BIT (ae_gen[b], ptr->index)). */
6710 SET_BIT (ae_kill[b], ptr->index);
6713 SET_BIT (transp[b], ptr->index);
6716 /* Any block with no exits calls some non-returning function, so
6717 we better mark the store killed here, or we might not store to
6718 it at all. If we knew it was abort, we wouldn't have to store,
6719 but we don't know that for sure. */
6722 fprintf (gcse_file, "ST_avail and ST_antic (shown under loads..)\n");
6723 print_ldst_list (gcse_file);
6724 dump_sbitmap_vector (gcse_file, "st_antloc", "", st_antloc, n_basic_blocks);
6725 dump_sbitmap_vector (gcse_file, "st_kill", "", ae_kill, n_basic_blocks);
6726 dump_sbitmap_vector (gcse_file, "Transpt", "", transp, n_basic_blocks);
6727 dump_sbitmap_vector (gcse_file, "st_avloc", "", ae_gen, n_basic_blocks);
6731 /* Insert an instruction at the begining of a basic block, and update
6732 the BLOCK_HEAD if needed. */
6735 insert_insn_start_bb (insn, bb)
6739 /* Insert at start of successor block. */
6740 rtx prev = PREV_INSN (bb->head);
6741 rtx before = bb->head;
6744 if (GET_CODE (before) != CODE_LABEL
6745 && (GET_CODE (before) != NOTE
6746 || NOTE_LINE_NUMBER (before) != NOTE_INSN_BASIC_BLOCK))
6749 if (prev == bb->end)
6751 before = NEXT_INSN (before);
6754 insn = emit_insn_after (insn, prev);
6756 if (prev == bb->end)
6759 set_block_for_new_insns (insn, bb);
6763 fprintf (gcse_file, "STORE_MOTION insert store at start of BB %d:\n",
6765 print_inline_rtx (gcse_file, insn, 6);
6766 fprintf (gcse_file, "\n");
6770 /* This routine will insert a store on an edge. EXPR is the ldst entry for
6771 the memory reference, and E is the edge to insert it on. Returns non-zero
6772 if an edge insertion was performed. */
6775 insert_store (expr, e)
6776 struct ls_expr * expr;
6783 /* We did all the deleted before this insert, so if we didn't delete a
6784 store, then we haven't set the reaching reg yet either. */
6785 if (expr->reaching_reg == NULL_RTX)
6788 reg = expr->reaching_reg;
6789 insn = gen_move_insn (expr->pattern, reg);
6791 /* If we are inserting this expression on ALL predecessor edges of a BB,
6792 insert it at the start of the BB, and reset the insert bits on the other
6793 edges so we don;t try to insert it on the other edges. */
6795 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
6797 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
6798 if (index == EDGE_INDEX_NO_EDGE)
6800 if (! TEST_BIT (pre_insert_map[index], expr->index))
6804 /* If tmp is NULL, we found an insertion on every edge, blank the
6805 insertion vector for these edges, and insert at the start of the BB. */
6806 if (!tmp && bb != EXIT_BLOCK_PTR)
6808 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
6810 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
6811 RESET_BIT (pre_insert_map[index], expr->index);
6813 insert_insn_start_bb (insn, bb);
6817 /* We can't insert on this edge, so we'll insert at the head of the
6818 successors block. See Morgan, sec 10.5. */
6819 if ((e->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
6821 insert_insn_start_bb (insn, bb);
6825 insert_insn_on_edge (insn, e);
6829 fprintf (gcse_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
6830 e->src->index, e->dest->index);
6831 print_inline_rtx (gcse_file, insn, 6);
6832 fprintf (gcse_file, "\n");
6838 /* This routine will replace a store with a SET to a specified register. */
6841 replace_store_insn (reg, del, bb)
6847 insn = gen_move_insn (reg, SET_SRC (PATTERN (del)));
6848 insn = emit_insn_after (insn, del);
6849 set_block_for_new_insns (insn, bb);
6854 "STORE_MOTION delete insn in BB %d:\n ", bb->index);
6855 print_inline_rtx (gcse_file, del, 6);
6856 fprintf(gcse_file, "\nSTORE MOTION replaced with insn:\n ");
6857 print_inline_rtx (gcse_file, insn, 6);
6858 fprintf(gcse_file, "\n");
6864 if (bb->head == del)
6871 /* Delete a store, but copy the value that would have been stored into
6872 the reaching_reg for later storing. */
6875 delete_store (expr, bb)
6876 struct ls_expr * expr;
6881 if (expr->reaching_reg == NULL_RTX)
6882 expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
6885 /* If there is more than 1 store, the earlier ones will be dead,
6886 but it doesn't hurt to replace them here. */
6887 reg = expr->reaching_reg;
6889 for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
6892 if (BLOCK_FOR_INSN (del) == bb)
6894 /* We know there is only one since we deleted redundant
6895 ones during the available computation. */
6896 replace_store_insn (reg, del, bb);
6902 /* Free memory used by store motion. */
6905 free_store_memory ()
6910 sbitmap_vector_free (ae_gen);
6912 sbitmap_vector_free (ae_kill);
6914 sbitmap_vector_free (transp);
6916 sbitmap_vector_free (st_antloc);
6918 sbitmap_vector_free (pre_insert_map);
6920 sbitmap_vector_free (pre_delete_map);
6921 if (reg_set_in_block)
6922 sbitmap_vector_free (reg_set_in_block);
6924 ae_gen = ae_kill = transp = st_antloc = NULL;
6925 pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
6928 /* Perform store motion. Much like gcse, except we move expressions the
6929 other way by looking at the flowgraph in reverse. */
6935 struct ls_expr * ptr;
6936 int update_flow = 0;
6940 fprintf (gcse_file, "before store motion\n");
6941 print_rtl (gcse_file, get_insns ());
6945 init_alias_analysis ();
6947 /* Find all the stores that are live to the end of their block. */
6948 num_stores = compute_store_table ();
6949 if (num_stores == 0)
6951 sbitmap_vector_free (reg_set_in_block);
6952 end_alias_analysis ();
6956 /* Now compute whats actually available to move. */
6957 add_noreturn_fake_exit_edges ();
6958 build_store_vectors ();
6960 edge_list = pre_edge_rev_lcm (gcse_file, num_stores, transp, ae_gen,
6961 st_antloc, ae_kill, &pre_insert_map,
6964 /* Now we want to insert the new stores which are going to be needed. */
6965 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6967 for (x = 0; x < n_basic_blocks; x++)
6968 if (TEST_BIT (pre_delete_map[x], ptr->index))
6969 delete_store (ptr, BASIC_BLOCK (x));
6971 for (x = 0; x < NUM_EDGES (edge_list); x++)
6972 if (TEST_BIT (pre_insert_map[x], ptr->index))
6973 update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
6977 commit_edge_insertions ();
6979 free_store_memory ();
6980 free_edge_list (edge_list);
6981 remove_fake_edges ();
6982 end_alias_analysis ();