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, 2002
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
24 - reordering of memory allocation and freeing to be more space efficient
25 - do rough calc of how many regs are needed in each block, and a rough
26 calc of how many regs are available in each class and use that to
27 throttle back the code in cases where RTX_COST is minimal.
28 - a store to the same address as a load does not kill the load if the
29 source of the store is also the destination of the load. Handling this
30 allows more load motion, particularly out of loops.
31 - ability to realloc sbitmap vectors would allow one initial computation
32 of reg_set_in_block with only subsequent additions, rather than
33 recomputing it for each pass
37 /* References searched while implementing this.
39 Compilers Principles, Techniques and Tools
43 Global Optimization by Suppression of Partial Redundancies
45 communications of the acm, Vol. 22, Num. 2, Feb. 1979
47 A Portable Machine-Independent Global Optimizer - Design and Measurements
49 Stanford Ph.D. thesis, Dec. 1983
51 A Fast Algorithm for Code Movement Optimization
53 SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988
55 A Solution to a Problem with Morel and Renvoise's
56 Global Optimization by Suppression of Partial Redundancies
57 K-H Drechsler, M.P. Stadel
58 ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988
60 Practical Adaptation of the Global Optimization
61 Algorithm of Morel and Renvoise
63 ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991
65 Efficiently Computing Static Single Assignment Form and the Control
67 R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck
68 ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991
71 J. Knoop, O. Ruthing, B. Steffen
72 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
74 What's In a Region? Or Computing Control Dependence Regions in Near-Linear
75 Time for Reducible Flow Control
77 ACM Letters on Programming Languages and Systems,
78 Vol. 2, Num. 1-4, Mar-Dec 1993
80 An Efficient Representation for Sparse Sets
81 Preston Briggs, Linda Torczon
82 ACM Letters on Programming Languages and Systems,
83 Vol. 2, Num. 1-4, Mar-Dec 1993
85 A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion
86 K-H Drechsler, M.P. Stadel
87 ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993
89 Partial Dead Code Elimination
90 J. Knoop, O. Ruthing, B. Steffen
91 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
93 Effective Partial Redundancy Elimination
94 P. Briggs, K.D. Cooper
95 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
97 The Program Structure Tree: Computing Control Regions in Linear Time
98 R. Johnson, D. Pearson, K. Pingali
99 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
101 Optimal Code Motion: Theory and Practice
102 J. Knoop, O. Ruthing, B. Steffen
103 ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994
105 The power of assignment motion
106 J. Knoop, O. Ruthing, B. Steffen
107 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
109 Global code motion / global value numbering
111 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
113 Value Driven Redundancy Elimination
115 Rice University Ph.D. thesis, Apr. 1996
119 Massively Scalar Compiler Project, Rice University, Sep. 1996
121 High Performance Compilers for Parallel Computing
125 Advanced Compiler Design and Implementation
127 Morgan Kaufmann, 1997
129 Building an Optimizing Compiler
133 People wishing to speed up the code here should read:
134 Elimination Algorithms for Data Flow Analysis
135 B.G. Ryder, M.C. Paull
136 ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986
138 How to Analyze Large Programs Efficiently and Informatively
139 D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck
140 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
142 People wishing to do something different can find various possibilities
143 in the above papers and elsewhere.
153 #include "hard-reg-set.h"
156 #include "insn-config.h"
158 #include "basic-block.h"
160 #include "function.h"
167 #define obstack_chunk_alloc gmalloc
168 #define obstack_chunk_free free
170 /* Propagate flow information through back edges and thus enable PRE's
171 moving loop invariant calculations out of loops.
173 Originally this tended to create worse overall code, but several
174 improvements during the development of PRE seem to have made following
175 back edges generally a win.
177 Note much of the loop invariant code motion done here would normally
178 be done by loop.c, which has more heuristics for when to move invariants
179 out of loops. At some point we might need to move some of those
180 heuristics into gcse.c. */
181 #define FOLLOW_BACK_EDGES 1
183 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
184 are a superset of those done by GCSE.
186 We perform the following steps:
188 1) Compute basic block information.
190 2) Compute table of places where registers are set.
192 3) Perform copy/constant propagation.
194 4) Perform global cse.
196 5) Perform another pass of copy/constant propagation.
198 Two passes of copy/constant propagation are done because the first one
199 enables more GCSE and the second one helps to clean up the copies that
200 GCSE creates. This is needed more for PRE than for Classic because Classic
201 GCSE will try to use an existing register containing the common
202 subexpression rather than create a new one. This is harder to do for PRE
203 because of the code motion (which Classic GCSE doesn't do).
205 Expressions we are interested in GCSE-ing are of the form
206 (set (pseudo-reg) (expression)).
207 Function want_to_gcse_p says what these are.
209 PRE handles moving invariant expressions out of loops (by treating them as
210 partially redundant).
212 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
213 assignment) based GVN (global value numbering). L. T. Simpson's paper
214 (Rice University) on value numbering is a useful reference for this.
216 **********************
218 We used to support multiple passes but there are diminishing returns in
219 doing so. The first pass usually makes 90% of the changes that are doable.
220 A second pass can make a few more changes made possible by the first pass.
221 Experiments show any further passes don't make enough changes to justify
224 A study of spec92 using an unlimited number of passes:
225 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
226 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
227 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
229 It was found doing copy propagation between each pass enables further
232 PRE is quite expensive in complicated functions because the DFA can take
233 awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can
234 be modified if one wants to experiment.
236 **********************
238 The steps for PRE are:
240 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
242 2) Perform the data flow analysis for PRE.
244 3) Delete the redundant instructions
246 4) Insert the required copies [if any] that make the partially
247 redundant instructions fully redundant.
249 5) For other reaching expressions, insert an instruction to copy the value
250 to a newly created pseudo that will reach the redundant instruction.
252 The deletion is done first so that when we do insertions we
253 know which pseudo reg to use.
255 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
256 argue it is not. The number of iterations for the algorithm to converge
257 is typically 2-4 so I don't view it as that expensive (relatively speaking).
259 PRE GCSE depends heavily on the second CSE pass to clean up the copies
260 we create. To make an expression reach the place where it's redundant,
261 the result of the expression is copied to a new register, and the redundant
262 expression is deleted by replacing it with this new register. Classic GCSE
263 doesn't have this problem as much as it computes the reaching defs of
264 each register in each block and thus can try to use an existing register.
266 **********************
268 A fair bit of simplicity is created by creating small functions for simple
269 tasks, even when the function is only called in one place. This may
270 measurably slow things down [or may not] by creating more function call
271 overhead than is necessary. The source is laid out so that it's trivial
272 to make the affected functions inline so that one can measure what speed
273 up, if any, can be achieved, and maybe later when things settle things can
276 Help stamp out big monolithic functions! */
278 /* GCSE global vars. */
281 static FILE *gcse_file;
283 /* Note whether or not we should run jump optimization after gcse. We
284 want to do this for two cases.
286 * If we changed any jumps via cprop.
288 * If we added any labels via edge splitting. */
290 static int run_jump_opt_after_gcse;
292 /* Bitmaps are normally not included in debugging dumps.
293 However it's useful to be able to print them from GDB.
294 We could create special functions for this, but it's simpler to
295 just allow passing stderr to the dump_foo fns. Since stderr can
296 be a macro, we store a copy here. */
297 static FILE *debug_stderr;
299 /* An obstack for our working variables. */
300 static struct obstack gcse_obstack;
302 /* Non-zero for each mode that supports (set (reg) (reg)).
303 This is trivially true for integer and floating point values.
304 It may or may not be true for condition codes. */
305 static char can_copy_p[(int) NUM_MACHINE_MODES];
307 /* Non-zero if can_copy_p has been initialized. */
308 static int can_copy_init_p;
310 struct reg_use {rtx reg_rtx; };
312 /* Hash table of expressions. */
316 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
318 /* Index in the available expression bitmaps. */
320 /* Next entry with the same hash. */
321 struct expr *next_same_hash;
322 /* List of anticipatable occurrences in basic blocks in the function.
323 An "anticipatable occurrence" is one that is the first occurrence in the
324 basic block, the operands are not modified in the basic block prior
325 to the occurrence and the output is not used between the start of
326 the block and the occurrence. */
327 struct occr *antic_occr;
328 /* List of available occurrence in basic blocks in the function.
329 An "available occurrence" is one that is the last occurrence in the
330 basic block and the operands are not modified by following statements in
331 the basic block [including this insn]. */
332 struct occr *avail_occr;
333 /* Non-null if the computation is PRE redundant.
334 The value is the newly created pseudo-reg to record a copy of the
335 expression in all the places that reach the redundant copy. */
339 /* Occurrence of an expression.
340 There is one per basic block. If a pattern appears more than once the
341 last appearance is used [or first for anticipatable expressions]. */
345 /* Next occurrence of this expression. */
347 /* The insn that computes the expression. */
349 /* Non-zero if this [anticipatable] occurrence has been deleted. */
351 /* Non-zero if this [available] occurrence has been copied to
353 /* ??? This is mutually exclusive with deleted_p, so they could share
358 /* Expression and copy propagation hash tables.
359 Each hash table is an array of buckets.
360 ??? It is known that if it were an array of entries, structure elements
361 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
362 not clear whether in the final analysis a sufficient amount of memory would
363 be saved as the size of the available expression bitmaps would be larger
364 [one could build a mapping table without holes afterwards though].
365 Someday I'll perform the computation and figure it out. */
367 /* Total size of the expression hash table, in elements. */
368 static unsigned int expr_hash_table_size;
371 This is an array of `expr_hash_table_size' elements. */
372 static struct expr **expr_hash_table;
374 /* Total size of the copy propagation hash table, in elements. */
375 static unsigned int set_hash_table_size;
378 This is an array of `set_hash_table_size' elements. */
379 static struct expr **set_hash_table;
381 /* Mapping of uids to cuids.
382 Only real insns get cuids. */
383 static int *uid_cuid;
385 /* Highest UID in UID_CUID. */
388 /* Get the cuid of an insn. */
389 #ifdef ENABLE_CHECKING
390 #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
392 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
395 /* Number of cuids. */
398 /* Mapping of cuids to insns. */
399 static rtx *cuid_insn;
401 /* Get insn from cuid. */
402 #define CUID_INSN(CUID) (cuid_insn[CUID])
404 /* Maximum register number in function prior to doing gcse + 1.
405 Registers created during this pass have regno >= max_gcse_regno.
406 This is named with "gcse" to not collide with global of same name. */
407 static unsigned int max_gcse_regno;
409 /* Maximum number of cse-able expressions found. */
412 /* Maximum number of assignments for copy propagation found. */
415 /* Table of registers that are modified.
417 For each register, each element is a list of places where the pseudo-reg
420 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
421 requires knowledge of which blocks kill which regs [and thus could use
422 a bitmap instead of the lists `reg_set_table' uses].
424 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
425 num-regs) [however perhaps it may be useful to keep the data as is]. One
426 advantage of recording things this way is that `reg_set_table' is fairly
427 sparse with respect to pseudo regs but for hard regs could be fairly dense
428 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
429 up functions like compute_transp since in the case of pseudo-regs we only
430 need to iterate over the number of times a pseudo-reg is set, not over the
431 number of basic blocks [clearly there is a bit of a slow down in the cases
432 where a pseudo is set more than once in a block, however it is believed
433 that the net effect is to speed things up]. This isn't done for hard-regs
434 because recording call-clobbered hard-regs in `reg_set_table' at each
435 function call can consume a fair bit of memory, and iterating over
436 hard-regs stored this way in compute_transp will be more expensive. */
438 typedef struct reg_set
440 /* The next setting of this register. */
441 struct reg_set *next;
442 /* The insn where it was set. */
446 static reg_set **reg_set_table;
448 /* Size of `reg_set_table'.
449 The table starts out at max_gcse_regno + slop, and is enlarged as
451 static int reg_set_table_size;
453 /* Amount to grow `reg_set_table' by when it's full. */
454 #define REG_SET_TABLE_SLOP 100
456 /* This is a list of expressions which are MEMs and will be used by load
458 Load motion tracks MEMs which aren't killed by
459 anything except itself. (ie, loads and stores to a single location).
460 We can then allow movement of these MEM refs with a little special
461 allowance. (all stores copy the same value to the reaching reg used
462 for the loads). This means all values used to store into memory must have
463 no side effects so we can re-issue the setter value.
464 Store Motion uses this structure as an expression table to track stores
465 which look interesting, and might be moveable towards the exit block. */
469 struct expr * expr; /* Gcse expression reference for LM. */
470 rtx pattern; /* Pattern of this mem. */
471 rtx loads; /* INSN list of loads seen. */
472 rtx stores; /* INSN list of stores seen. */
473 struct ls_expr * next; /* Next in the list. */
474 int invalid; /* Invalid for some reason. */
475 int index; /* If it maps to a bitmap index. */
476 int hash_index; /* Index when in a hash table. */
477 rtx reaching_reg; /* Register to use when re-writing. */
480 /* Head of the list of load/store memory refs. */
481 static struct ls_expr * pre_ldst_mems = NULL;
483 /* Bitmap containing one bit for each register in the program.
484 Used when performing GCSE to track which registers have been set since
485 the start of the basic block. */
486 static regset reg_set_bitmap;
488 /* For each block, a bitmap of registers set in the block.
489 This is used by expr_killed_p and compute_transp.
490 It is computed during hash table computation and not by compute_sets
491 as it includes registers added since the last pass (or between cprop and
492 gcse) and it's currently not easy to realloc sbitmap vectors. */
493 static sbitmap *reg_set_in_block;
495 /* Array, indexed by basic block number for a list of insns which modify
496 memory within that block. */
497 static rtx * modify_mem_list;
498 bitmap modify_mem_list_set;
500 /* This array parallels modify_mem_list, but is kept canonicalized. */
501 static rtx * canon_modify_mem_list;
502 bitmap canon_modify_mem_list_set;
503 /* Various variables for statistics gathering. */
505 /* Memory used in a pass.
506 This isn't intended to be absolutely precise. Its intent is only
507 to keep an eye on memory usage. */
508 static int bytes_used;
510 /* GCSE substitutions made. */
511 static int gcse_subst_count;
512 /* Number of copy instructions created. */
513 static int gcse_create_count;
514 /* Number of constants propagated. */
515 static int const_prop_count;
516 /* Number of copys propagated. */
517 static int copy_prop_count;
519 /* These variables are used by classic GCSE.
520 Normally they'd be defined a bit later, but `rd_gen' needs to
521 be declared sooner. */
523 /* Each block has a bitmap of each type.
524 The length of each blocks bitmap is:
526 max_cuid - for reaching definitions
527 n_exprs - for available expressions
529 Thus we view the bitmaps as 2 dimensional arrays. i.e.
530 rd_kill[block_num][cuid_num]
531 ae_kill[block_num][expr_num] */
533 /* For reaching defs */
534 static sbitmap *rd_kill, *rd_gen, *reaching_defs, *rd_out;
536 /* for available exprs */
537 static sbitmap *ae_kill, *ae_gen, *ae_in, *ae_out;
539 /* Objects of this type are passed around by the null-pointer check
541 struct null_pointer_info
543 /* The basic block being processed. */
544 basic_block current_block;
545 /* The first register to be handled in this pass. */
546 unsigned int min_reg;
547 /* One greater than the last register to be handled in this pass. */
548 unsigned int max_reg;
549 sbitmap *nonnull_local;
550 sbitmap *nonnull_killed;
553 static void compute_can_copy PARAMS ((void));
554 static char *gmalloc PARAMS ((unsigned int));
555 static char *grealloc PARAMS ((char *, unsigned int));
556 static char *gcse_alloc PARAMS ((unsigned long));
557 static void alloc_gcse_mem PARAMS ((rtx));
558 static void free_gcse_mem PARAMS ((void));
559 static void alloc_reg_set_mem PARAMS ((int));
560 static void free_reg_set_mem PARAMS ((void));
561 static int get_bitmap_width PARAMS ((int, int, int));
562 static void record_one_set PARAMS ((int, rtx));
563 static void record_set_info PARAMS ((rtx, rtx, void *));
564 static void compute_sets PARAMS ((rtx));
565 static void hash_scan_insn PARAMS ((rtx, int, int));
566 static void hash_scan_set PARAMS ((rtx, rtx, int));
567 static void hash_scan_clobber PARAMS ((rtx, rtx));
568 static void hash_scan_call PARAMS ((rtx, rtx));
569 static int want_to_gcse_p PARAMS ((rtx));
570 static int oprs_unchanged_p PARAMS ((rtx, rtx, int));
571 static int oprs_anticipatable_p PARAMS ((rtx, rtx));
572 static int oprs_available_p PARAMS ((rtx, rtx));
573 static void insert_expr_in_table PARAMS ((rtx, enum machine_mode, rtx,
575 static void insert_set_in_table PARAMS ((rtx, rtx));
576 static unsigned int hash_expr PARAMS ((rtx, enum machine_mode, int *, int));
577 static unsigned int hash_expr_1 PARAMS ((rtx, enum machine_mode, int *));
578 static unsigned int hash_string_1 PARAMS ((const char *));
579 static unsigned int hash_set PARAMS ((int, int));
580 static int expr_equiv_p PARAMS ((rtx, rtx));
581 static void record_last_reg_set_info PARAMS ((rtx, int));
582 static void record_last_mem_set_info PARAMS ((rtx));
583 static void record_last_set_info PARAMS ((rtx, rtx, void *));
584 static void compute_hash_table PARAMS ((int));
585 static void alloc_set_hash_table PARAMS ((int));
586 static void free_set_hash_table PARAMS ((void));
587 static void compute_set_hash_table PARAMS ((void));
588 static void alloc_expr_hash_table PARAMS ((unsigned int));
589 static void free_expr_hash_table PARAMS ((void));
590 static void compute_expr_hash_table PARAMS ((void));
591 static void dump_hash_table PARAMS ((FILE *, const char *, struct expr **,
593 static struct expr *lookup_expr PARAMS ((rtx));
594 static struct expr *lookup_set PARAMS ((unsigned int, rtx));
595 static struct expr *next_set PARAMS ((unsigned int, struct expr *));
596 static void reset_opr_set_tables PARAMS ((void));
597 static int oprs_not_set_p PARAMS ((rtx, rtx));
598 static void mark_call PARAMS ((rtx));
599 static void mark_set PARAMS ((rtx, rtx));
600 static void mark_clobber PARAMS ((rtx, rtx));
601 static void mark_oprs_set PARAMS ((rtx));
602 static void alloc_cprop_mem PARAMS ((int, int));
603 static void free_cprop_mem PARAMS ((void));
604 static void compute_transp PARAMS ((rtx, int, sbitmap *, int));
605 static void compute_transpout PARAMS ((void));
606 static void compute_local_properties PARAMS ((sbitmap *, sbitmap *, sbitmap *,
608 static void compute_cprop_data PARAMS ((void));
609 static void find_used_regs PARAMS ((rtx *, void *));
610 static int try_replace_reg PARAMS ((rtx, rtx, rtx));
611 static struct expr *find_avail_set PARAMS ((int, rtx));
612 static int cprop_jump PARAMS ((basic_block, rtx, rtx, rtx, rtx));
613 static void mems_conflict_for_gcse_p PARAMS ((rtx, rtx, void *));
614 static int load_killed_in_block_p PARAMS ((basic_block, int, rtx, int));
615 static void canon_list_insert PARAMS ((rtx, rtx, void *));
616 static int cprop_insn PARAMS ((basic_block, rtx, int));
617 static int cprop PARAMS ((int));
618 static int one_cprop_pass PARAMS ((int, int));
619 static struct expr *find_bypass_set PARAMS ((int, int));
620 static int bypass_block PARAMS ((basic_block, rtx, rtx));
621 static int bypass_conditional_jumps PARAMS ((void));
622 static void alloc_pre_mem PARAMS ((int, int));
623 static void free_pre_mem PARAMS ((void));
624 static void compute_pre_data PARAMS ((void));
625 static int pre_expr_reaches_here_p PARAMS ((basic_block, struct expr *,
627 static void insert_insn_end_bb PARAMS ((struct expr *, basic_block, int));
628 static void pre_insert_copy_insn PARAMS ((struct expr *, rtx));
629 static void pre_insert_copies PARAMS ((void));
630 static int pre_delete PARAMS ((void));
631 static int pre_gcse PARAMS ((void));
632 static int one_pre_gcse_pass PARAMS ((int));
633 static void add_label_notes PARAMS ((rtx, rtx));
634 static void alloc_code_hoist_mem PARAMS ((int, int));
635 static void free_code_hoist_mem PARAMS ((void));
636 static void compute_code_hoist_vbeinout PARAMS ((void));
637 static void compute_code_hoist_data PARAMS ((void));
638 static int hoist_expr_reaches_here_p PARAMS ((basic_block, int, basic_block,
640 static void hoist_code PARAMS ((void));
641 static int one_code_hoisting_pass PARAMS ((void));
642 static void alloc_rd_mem PARAMS ((int, int));
643 static void free_rd_mem PARAMS ((void));
644 static void handle_rd_kill_set PARAMS ((rtx, int, basic_block));
645 static void compute_kill_rd PARAMS ((void));
646 static void compute_rd PARAMS ((void));
647 static void alloc_avail_expr_mem PARAMS ((int, int));
648 static void free_avail_expr_mem PARAMS ((void));
649 static void compute_ae_gen PARAMS ((void));
650 static int expr_killed_p PARAMS ((rtx, basic_block));
651 static void compute_ae_kill PARAMS ((sbitmap *, sbitmap *));
652 static int expr_reaches_here_p PARAMS ((struct occr *, struct expr *,
654 static rtx computing_insn PARAMS ((struct expr *, rtx));
655 static int def_reaches_here_p PARAMS ((rtx, rtx));
656 static int can_disregard_other_sets PARAMS ((struct reg_set **, rtx, int));
657 static int handle_avail_expr PARAMS ((rtx, struct expr *));
658 static int classic_gcse PARAMS ((void));
659 static int one_classic_gcse_pass PARAMS ((int));
660 static void invalidate_nonnull_info PARAMS ((rtx, rtx, void *));
661 static void delete_null_pointer_checks_1 PARAMS ((unsigned int *,
662 sbitmap *, sbitmap *,
663 struct null_pointer_info *));
664 static rtx process_insert_insn PARAMS ((struct expr *));
665 static int pre_edge_insert PARAMS ((struct edge_list *, struct expr **));
666 static int expr_reaches_here_p_work PARAMS ((struct occr *, struct expr *,
667 basic_block, int, char *));
668 static int pre_expr_reaches_here_p_work PARAMS ((basic_block, struct expr *,
669 basic_block, char *));
670 static struct ls_expr * ldst_entry PARAMS ((rtx));
671 static void free_ldst_entry PARAMS ((struct ls_expr *));
672 static void free_ldst_mems PARAMS ((void));
673 static void print_ldst_list PARAMS ((FILE *));
674 static struct ls_expr * find_rtx_in_ldst PARAMS ((rtx));
675 static int enumerate_ldsts PARAMS ((void));
676 static inline struct ls_expr * first_ls_expr PARAMS ((void));
677 static inline struct ls_expr * next_ls_expr PARAMS ((struct ls_expr *));
678 static int simple_mem PARAMS ((rtx));
679 static void invalidate_any_buried_refs PARAMS ((rtx));
680 static void compute_ld_motion_mems PARAMS ((void));
681 static void trim_ld_motion_mems PARAMS ((void));
682 static void update_ld_motion_stores PARAMS ((struct expr *));
683 static void reg_set_info PARAMS ((rtx, rtx, void *));
684 static int store_ops_ok PARAMS ((rtx, basic_block));
685 static void find_moveable_store PARAMS ((rtx));
686 static int compute_store_table PARAMS ((void));
687 static int load_kills_store PARAMS ((rtx, rtx));
688 static int find_loads PARAMS ((rtx, rtx));
689 static int store_killed_in_insn PARAMS ((rtx, rtx));
690 static int store_killed_after PARAMS ((rtx, rtx, basic_block));
691 static int store_killed_before PARAMS ((rtx, rtx, basic_block));
692 static void build_store_vectors PARAMS ((void));
693 static void insert_insn_start_bb PARAMS ((rtx, basic_block));
694 static int insert_store PARAMS ((struct ls_expr *, edge));
695 static void replace_store_insn PARAMS ((rtx, rtx, basic_block));
696 static void delete_store PARAMS ((struct ls_expr *,
698 static void free_store_memory PARAMS ((void));
699 static void store_motion PARAMS ((void));
700 static void free_insn_expr_list_list PARAMS ((rtx *));
701 static void clear_modify_mem_tables PARAMS ((void));
702 static void free_modify_mem_tables PARAMS ((void));
703 static rtx gcse_emit_move_after PARAMS ((rtx, rtx, rtx));
705 /* Entry point for global common subexpression elimination.
706 F is the first instruction in the function. */
714 /* Bytes used at start of pass. */
715 int initial_bytes_used;
716 /* Maximum number of bytes used by a pass. */
718 /* Point to release obstack data from for each pass. */
719 char *gcse_obstack_bottom;
721 /* Insertion of instructions on edges can create new basic blocks; we
722 need the original basic block count so that we can properly deallocate
723 arrays sized on the number of basic blocks originally in the cfg. */
725 /* We do not construct an accurate cfg in functions which call
726 setjmp, so just punt to be safe. */
727 if (current_function_calls_setjmp)
730 /* Assume that we do not need to run jump optimizations after gcse. */
731 run_jump_opt_after_gcse = 0;
733 /* For calling dump_foo fns from gdb. */
734 debug_stderr = stderr;
737 /* Identify the basic block information for this function, including
738 successors and predecessors. */
739 max_gcse_regno = max_reg_num ();
742 dump_flow_info (file);
744 orig_bb_count = n_basic_blocks;
745 /* Return if there's nothing to do. */
746 if (n_basic_blocks <= 1)
749 /* Trying to perform global optimizations on flow graphs which have
750 a high connectivity will take a long time and is unlikely to be
753 In normal circumstances a cfg should have about twice as many edges
754 as blocks. But we do not want to punish small functions which have
755 a couple switch statements. So we require a relatively large number
756 of basic blocks and the ratio of edges to blocks to be high. */
757 if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
759 if (warn_disabled_optimization)
760 warning ("GCSE disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
761 n_basic_blocks, n_edges / n_basic_blocks);
765 /* If allocating memory for the cprop bitmap would take up too much
766 storage it's better just to disable the optimization. */
768 * SBITMAP_SET_SIZE (max_gcse_regno)
769 * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
771 if (warn_disabled_optimization)
772 warning ("GCSE disabled: %d basic blocks and %d registers",
773 n_basic_blocks, max_gcse_regno);
778 /* See what modes support reg/reg copy operations. */
779 if (! can_copy_init_p)
785 gcc_obstack_init (&gcse_obstack);
789 init_alias_analysis ();
790 /* Record where pseudo-registers are set. This data is kept accurate
791 during each pass. ??? We could also record hard-reg information here
792 [since it's unchanging], however it is currently done during hash table
795 It may be tempting to compute MEM set information here too, but MEM sets
796 will be subject to code motion one day and thus we need to compute
797 information about memory sets when we build the hash tables. */
799 alloc_reg_set_mem (max_gcse_regno);
803 initial_bytes_used = bytes_used;
805 gcse_obstack_bottom = gcse_alloc (1);
807 while (changed && pass < MAX_GCSE_PASSES)
811 fprintf (file, "GCSE pass %d\n\n", pass + 1);
813 /* Initialize bytes_used to the space for the pred/succ lists,
814 and the reg_set_table data. */
815 bytes_used = initial_bytes_used;
817 /* Each pass may create new registers, so recalculate each time. */
818 max_gcse_regno = max_reg_num ();
822 /* Don't allow constant propagation to modify jumps
824 changed = one_cprop_pass (pass + 1, 0);
827 changed |= one_classic_gcse_pass (pass + 1);
830 changed |= one_pre_gcse_pass (pass + 1);
831 /* We may have just created new basic blocks. Release and
832 recompute various things which are sized on the number of
836 free_modify_mem_tables ();
838 = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
839 canon_modify_mem_list
840 = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
841 memset ((char *) modify_mem_list, 0, last_basic_block * sizeof (rtx));
842 memset ((char *) canon_modify_mem_list, 0, last_basic_block * 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 /* Store motion disabled until it is fixed. */
910 if (0 && !optimize_size && flag_gcse_sm)
912 /* Record where pseudo-registers are set. */
913 return run_jump_opt_after_gcse;
916 /* Misc. utilities. */
918 /* Compute which modes support reg/reg copy operations. */
924 #ifndef AVOID_CCMODE_COPIES
927 memset (can_copy_p, 0, NUM_MACHINE_MODES);
930 for (i = 0; i < NUM_MACHINE_MODES; i++)
931 if (GET_MODE_CLASS (i) == MODE_CC)
933 #ifdef AVOID_CCMODE_COPIES
936 reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1);
937 insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
938 if (recog (PATTERN (insn), insn, NULL) >= 0)
948 /* Cover function to xmalloc to record bytes allocated. */
955 return xmalloc (size);
958 /* Cover function to xrealloc.
959 We don't record the additional size since we don't know it.
960 It won't affect memory usage stats much anyway. */
967 return xrealloc (ptr, size);
970 /* Cover function to obstack_alloc.
971 We don't need to record the bytes allocated here since
972 obstack_chunk_alloc is set to gmalloc. */
978 return (char *) obstack_alloc (&gcse_obstack, size);
981 /* Allocate memory for the cuid mapping array,
982 and reg/memory set tracking tables.
984 This is called at the start of each pass. */
993 /* Find the largest UID and create a mapping from UIDs to CUIDs.
994 CUIDs are like UIDs except they increase monotonically, have no gaps,
995 and only apply to real insns. */
997 max_uid = get_max_uid ();
998 n = (max_uid + 1) * sizeof (int);
999 uid_cuid = (int *) gmalloc (n);
1000 memset ((char *) uid_cuid, 0, n);
1001 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
1004 uid_cuid[INSN_UID (insn)] = i++;
1006 uid_cuid[INSN_UID (insn)] = i;
1009 /* Create a table mapping cuids to insns. */
1012 n = (max_cuid + 1) * sizeof (rtx);
1013 cuid_insn = (rtx *) gmalloc (n);
1014 memset ((char *) cuid_insn, 0, n);
1015 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
1017 CUID_INSN (i++) = insn;
1019 /* Allocate vars to track sets of regs. */
1020 reg_set_bitmap = BITMAP_XMALLOC ();
1022 /* Allocate vars to track sets of regs, memory per block. */
1023 reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (last_basic_block,
1025 /* Allocate array to keep a list of insns which modify memory in each
1027 modify_mem_list = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
1028 canon_modify_mem_list = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
1029 memset ((char *) modify_mem_list, 0, last_basic_block * sizeof (rtx));
1030 memset ((char *) canon_modify_mem_list, 0, last_basic_block * sizeof (rtx));
1031 modify_mem_list_set = BITMAP_XMALLOC ();
1032 canon_modify_mem_list_set = BITMAP_XMALLOC ();
1035 /* Free memory allocated by alloc_gcse_mem. */
1043 BITMAP_XFREE (reg_set_bitmap);
1045 sbitmap_vector_free (reg_set_in_block);
1046 free_modify_mem_tables ();
1047 BITMAP_XFREE (modify_mem_list_set);
1048 BITMAP_XFREE (canon_modify_mem_list_set);
1051 /* Many of the global optimization algorithms work by solving dataflow
1052 equations for various expressions. Initially, some local value is
1053 computed for each expression in each block. Then, the values across the
1054 various blocks are combined (by following flow graph edges) to arrive at
1055 global values. Conceptually, each set of equations is independent. We
1056 may therefore solve all the equations in parallel, solve them one at a
1057 time, or pick any intermediate approach.
1059 When you're going to need N two-dimensional bitmaps, each X (say, the
1060 number of blocks) by Y (say, the number of expressions), call this
1061 function. It's not important what X and Y represent; only that Y
1062 correspond to the things that can be done in parallel. This function will
1063 return an appropriate chunking factor C; you should solve C sets of
1064 equations in parallel. By going through this function, we can easily
1065 trade space against time; by solving fewer equations in parallel we use
1069 get_bitmap_width (n, x, y)
1074 /* It's not really worth figuring out *exactly* how much memory will
1075 be used by a particular choice. The important thing is to get
1076 something approximately right. */
1077 size_t max_bitmap_memory = 10 * 1024 * 1024;
1079 /* The number of bytes we'd use for a single column of minimum
1081 size_t column_size = n * x * sizeof (SBITMAP_ELT_TYPE);
1083 /* Often, it's reasonable just to solve all the equations in
1085 if (column_size * SBITMAP_SET_SIZE (y) <= max_bitmap_memory)
1088 /* Otherwise, pick the largest width we can, without going over the
1090 return SBITMAP_ELT_BITS * ((max_bitmap_memory + column_size - 1)
1094 /* Compute the local properties of each recorded expression.
1096 Local properties are those that are defined by the block, irrespective of
1099 An expression is transparent in a block if its operands are not modified
1102 An expression is computed (locally available) in a block if it is computed
1103 at least once and expression would contain the same value if the
1104 computation was moved to the end of the block.
1106 An expression is locally anticipatable in a block if it is computed at
1107 least once and expression would contain the same value if the computation
1108 was moved to the beginning of the block.
1110 We call this routine for cprop, pre and code hoisting. They all compute
1111 basically the same information and thus can easily share this code.
1113 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1114 properties. If NULL, then it is not necessary to compute or record that
1115 particular property.
1117 SETP controls which hash table to look at. If zero, this routine looks at
1118 the expr hash table; if nonzero this routine looks at the set hash table.
1119 Additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1123 compute_local_properties (transp, comp, antloc, setp)
1129 unsigned int i, hash_table_size;
1130 struct expr **hash_table;
1132 /* Initialize any bitmaps that were passed in. */
1136 sbitmap_vector_zero (transp, last_basic_block);
1138 sbitmap_vector_ones (transp, last_basic_block);
1142 sbitmap_vector_zero (comp, last_basic_block);
1144 sbitmap_vector_zero (antloc, last_basic_block);
1146 /* We use the same code for cprop, pre and hoisting. For cprop
1147 we care about the set hash table, for pre and hoisting we
1148 care about the expr hash table. */
1149 hash_table_size = setp ? set_hash_table_size : expr_hash_table_size;
1150 hash_table = setp ? set_hash_table : expr_hash_table;
1152 for (i = 0; i < hash_table_size; i++)
1156 for (expr = hash_table[i]; expr != NULL; expr = expr->next_same_hash)
1158 int indx = expr->bitmap_index;
1161 /* The expression is transparent in this block if it is not killed.
1162 We start by assuming all are transparent [none are killed], and
1163 then reset the bits for those that are. */
1165 compute_transp (expr->expr, indx, transp, setp);
1167 /* The occurrences recorded in antic_occr are exactly those that
1168 we want to set to non-zero in ANTLOC. */
1170 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
1172 SET_BIT (antloc[BLOCK_NUM (occr->insn)], indx);
1174 /* While we're scanning the table, this is a good place to
1176 occr->deleted_p = 0;
1179 /* The occurrences recorded in avail_occr are exactly those that
1180 we want to set to non-zero in COMP. */
1182 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
1184 SET_BIT (comp[BLOCK_NUM (occr->insn)], indx);
1186 /* While we're scanning the table, this is a good place to
1191 /* While we're scanning the table, this is a good place to
1193 expr->reaching_reg = 0;
1198 /* Register set information.
1200 `reg_set_table' records where each register is set or otherwise
1203 static struct obstack reg_set_obstack;
1206 alloc_reg_set_mem (n_regs)
1211 reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
1212 n = reg_set_table_size * sizeof (struct reg_set *);
1213 reg_set_table = (struct reg_set **) gmalloc (n);
1214 memset ((char *) reg_set_table, 0, n);
1216 gcc_obstack_init (®_set_obstack);
1222 free (reg_set_table);
1223 obstack_free (®_set_obstack, NULL);
1226 /* Record REGNO in the reg_set table. */
1229 record_one_set (regno, insn)
1233 /* Allocate a new reg_set element and link it onto the list. */
1234 struct reg_set *new_reg_info;
1236 /* If the table isn't big enough, enlarge it. */
1237 if (regno >= reg_set_table_size)
1239 int new_size = regno + REG_SET_TABLE_SLOP;
1242 = (struct reg_set **) grealloc ((char *) reg_set_table,
1243 new_size * sizeof (struct reg_set *));
1244 memset ((char *) (reg_set_table + reg_set_table_size), 0,
1245 (new_size - reg_set_table_size) * sizeof (struct reg_set *));
1246 reg_set_table_size = new_size;
1249 new_reg_info = (struct reg_set *) obstack_alloc (®_set_obstack,
1250 sizeof (struct reg_set));
1251 bytes_used += sizeof (struct reg_set);
1252 new_reg_info->insn = insn;
1253 new_reg_info->next = reg_set_table[regno];
1254 reg_set_table[regno] = new_reg_info;
1257 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1258 an insn. The DATA is really the instruction in which the SET is
1262 record_set_info (dest, setter, data)
1263 rtx dest, setter ATTRIBUTE_UNUSED;
1266 rtx record_set_insn = (rtx) data;
1268 if (GET_CODE (dest) == REG && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
1269 record_one_set (REGNO (dest), record_set_insn);
1272 /* Scan the function and record each set of each pseudo-register.
1274 This is called once, at the start of the gcse pass. See the comments for
1275 `reg_set_table' for further documenation. */
1283 for (insn = f; insn != 0; insn = NEXT_INSN (insn))
1285 note_stores (PATTERN (insn), record_set_info, insn);
1288 /* Hash table support. */
1290 /* For each register, the cuid of the first/last insn in the block
1291 that set it, or -1 if not set. */
1292 #define NEVER_SET -1
1294 struct reg_avail_info
1296 basic_block last_bb;
1301 static struct reg_avail_info *reg_avail_info;
1302 static basic_block current_bb;
1305 /* See whether X, the source of a set, is something we want to consider for
1312 static rtx test_insn = 0;
1313 int num_clobbers = 0;
1316 switch (GET_CODE (x))
1330 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1331 if (general_operand (x, GET_MODE (x)))
1333 else if (GET_MODE (x) == VOIDmode)
1336 /* Otherwise, check if we can make a valid insn from it. First initialize
1337 our test insn if we haven't already. */
1341 = make_insn_raw (gen_rtx_SET (VOIDmode,
1342 gen_rtx_REG (word_mode,
1343 FIRST_PSEUDO_REGISTER * 2),
1345 NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0;
1346 ggc_add_rtx_root (&test_insn, 1);
1349 /* Now make an insn like the one we would make when GCSE'ing and see if
1351 PUT_MODE (SET_DEST (PATTERN (test_insn)), GET_MODE (x));
1352 SET_SRC (PATTERN (test_insn)) = x;
1353 return ((icode = recog (PATTERN (test_insn), test_insn, &num_clobbers)) >= 0
1354 && (num_clobbers == 0 || ! added_clobbers_hard_reg_p (icode)));
1357 /* Return non-zero if the operands of expression X are unchanged from the
1358 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1359 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1362 oprs_unchanged_p (x, insn, avail_p)
1373 code = GET_CODE (x);
1378 struct reg_avail_info *info = ®_avail_info[REGNO (x)];
1380 if (info->last_bb != current_bb)
1383 return info->last_set < INSN_CUID (insn);
1385 return info->first_set >= INSN_CUID (insn);
1389 if (load_killed_in_block_p (current_bb, INSN_CUID (insn),
1393 return oprs_unchanged_p (XEXP (x, 0), insn, avail_p);
1419 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1423 /* If we are about to do the last recursive call needed at this
1424 level, change it into iteration. This function is called enough
1427 return oprs_unchanged_p (XEXP (x, i), insn, avail_p);
1429 else if (! oprs_unchanged_p (XEXP (x, i), insn, avail_p))
1432 else if (fmt[i] == 'E')
1433 for (j = 0; j < XVECLEN (x, i); j++)
1434 if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p))
1441 /* Used for communication between mems_conflict_for_gcse_p and
1442 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1443 conflict between two memory references. */
1444 static int gcse_mems_conflict_p;
1446 /* Used for communication between mems_conflict_for_gcse_p and
1447 load_killed_in_block_p. A memory reference for a load instruction,
1448 mems_conflict_for_gcse_p will see if a memory store conflicts with
1449 this memory load. */
1450 static rtx gcse_mem_operand;
1452 /* DEST is the output of an instruction. If it is a memory reference, and
1453 possibly conflicts with the load found in gcse_mem_operand, then set
1454 gcse_mems_conflict_p to a nonzero value. */
1457 mems_conflict_for_gcse_p (dest, setter, data)
1458 rtx dest, setter ATTRIBUTE_UNUSED;
1459 void *data ATTRIBUTE_UNUSED;
1461 while (GET_CODE (dest) == SUBREG
1462 || GET_CODE (dest) == ZERO_EXTRACT
1463 || GET_CODE (dest) == SIGN_EXTRACT
1464 || GET_CODE (dest) == STRICT_LOW_PART)
1465 dest = XEXP (dest, 0);
1467 /* If DEST is not a MEM, then it will not conflict with the load. Note
1468 that function calls are assumed to clobber memory, but are handled
1470 if (GET_CODE (dest) != MEM)
1473 /* If we are setting a MEM in our list of specially recognized MEMs,
1474 don't mark as killed this time. */
1476 if (dest == gcse_mem_operand && pre_ldst_mems != NULL)
1478 if (!find_rtx_in_ldst (dest))
1479 gcse_mems_conflict_p = 1;
1483 if (true_dependence (dest, GET_MODE (dest), gcse_mem_operand,
1485 gcse_mems_conflict_p = 1;
1488 /* Return nonzero if the expression in X (a memory reference) is killed
1489 in block BB before or after the insn with the CUID in UID_LIMIT.
1490 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1493 To check the entire block, set UID_LIMIT to max_uid + 1 and
1497 load_killed_in_block_p (bb, uid_limit, x, avail_p)
1503 rtx list_entry = modify_mem_list[bb->index];
1507 /* Ignore entries in the list that do not apply. */
1509 && INSN_CUID (XEXP (list_entry, 0)) < uid_limit)
1511 && INSN_CUID (XEXP (list_entry, 0)) > uid_limit))
1513 list_entry = XEXP (list_entry, 1);
1517 setter = XEXP (list_entry, 0);
1519 /* If SETTER is a call everything is clobbered. Note that calls
1520 to pure functions are never put on the list, so we need not
1521 worry about them. */
1522 if (GET_CODE (setter) == CALL_INSN)
1525 /* SETTER must be an INSN of some kind that sets memory. Call
1526 note_stores to examine each hunk of memory that is modified.
1528 The note_stores interface is pretty limited, so we have to
1529 communicate via global variables. Yuk. */
1530 gcse_mem_operand = x;
1531 gcse_mems_conflict_p = 0;
1532 note_stores (PATTERN (setter), mems_conflict_for_gcse_p, NULL);
1533 if (gcse_mems_conflict_p)
1535 list_entry = XEXP (list_entry, 1);
1540 /* Return non-zero if the operands of expression X are unchanged from
1541 the start of INSN's basic block up to but not including INSN. */
1544 oprs_anticipatable_p (x, insn)
1547 return oprs_unchanged_p (x, insn, 0);
1550 /* Return non-zero if the operands of expression X are unchanged from
1551 INSN to the end of INSN's basic block. */
1554 oprs_available_p (x, insn)
1557 return oprs_unchanged_p (x, insn, 1);
1560 /* Hash expression X.
1562 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1563 indicating if a volatile operand is found or if the expression contains
1564 something we don't want to insert in the table.
1566 ??? One might want to merge this with canon_hash. Later. */
1569 hash_expr (x, mode, do_not_record_p, hash_table_size)
1571 enum machine_mode mode;
1572 int *do_not_record_p;
1573 int hash_table_size;
1577 *do_not_record_p = 0;
1579 hash = hash_expr_1 (x, mode, do_not_record_p);
1580 return hash % hash_table_size;
1583 /* Hash a string. Just add its bytes up. */
1585 static inline unsigned
1590 const unsigned char *p = (const unsigned char *) ps;
1599 /* Subroutine of hash_expr to do the actual work. */
1602 hash_expr_1 (x, mode, do_not_record_p)
1604 enum machine_mode mode;
1605 int *do_not_record_p;
1612 /* Used to turn recursion into iteration. We can't rely on GCC's
1613 tail-recursion eliminatio since we need to keep accumulating values
1620 code = GET_CODE (x);
1624 hash += ((unsigned int) REG << 7) + REGNO (x);
1628 hash += (((unsigned int) CONST_INT << 7) + (unsigned int) mode
1629 + (unsigned int) INTVAL (x));
1633 /* This is like the general case, except that it only counts
1634 the integers representing the constant. */
1635 hash += (unsigned int) code + (unsigned int) GET_MODE (x);
1636 if (GET_MODE (x) != VOIDmode)
1637 for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++)
1638 hash += (unsigned int) XWINT (x, i);
1640 hash += ((unsigned int) CONST_DOUBLE_LOW (x)
1641 + (unsigned int) CONST_DOUBLE_HIGH (x));
1649 units = CONST_VECTOR_NUNITS (x);
1651 for (i = 0; i < units; ++i)
1653 elt = CONST_VECTOR_ELT (x, i);
1654 hash += hash_expr_1 (elt, GET_MODE (elt), do_not_record_p);
1660 /* Assume there is only one rtx object for any given label. */
1662 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1663 differences and differences between each stage's debugging dumps. */
1664 hash += (((unsigned int) LABEL_REF << 7)
1665 + CODE_LABEL_NUMBER (XEXP (x, 0)));
1670 /* Don't hash on the symbol's address to avoid bootstrap differences.
1671 Different hash values may cause expressions to be recorded in
1672 different orders and thus different registers to be used in the
1673 final assembler. This also avoids differences in the dump files
1674 between various stages. */
1676 const unsigned char *p = (const unsigned char *) XSTR (x, 0);
1679 h += (h << 7) + *p++; /* ??? revisit */
1681 hash += ((unsigned int) SYMBOL_REF << 7) + h;
1686 if (MEM_VOLATILE_P (x))
1688 *do_not_record_p = 1;
1692 hash += (unsigned int) MEM;
1693 /* We used alias set for hashing, but this is not good, since the alias
1694 set may differ in -fprofile-arcs and -fbranch-probabilities compilation
1695 causing the profiles to fail to match. */
1706 case UNSPEC_VOLATILE:
1707 *do_not_record_p = 1;
1711 if (MEM_VOLATILE_P (x))
1713 *do_not_record_p = 1;
1718 /* We don't want to take the filename and line into account. */
1719 hash += (unsigned) code + (unsigned) GET_MODE (x)
1720 + hash_string_1 (ASM_OPERANDS_TEMPLATE (x))
1721 + hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x))
1722 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x);
1724 if (ASM_OPERANDS_INPUT_LENGTH (x))
1726 for (i = 1; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
1728 hash += (hash_expr_1 (ASM_OPERANDS_INPUT (x, i),
1729 GET_MODE (ASM_OPERANDS_INPUT (x, i)),
1731 + hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT
1735 hash += hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x, 0));
1736 x = ASM_OPERANDS_INPUT (x, 0);
1737 mode = GET_MODE (x);
1747 hash += (unsigned) code + (unsigned) GET_MODE (x);
1748 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1752 /* If we are about to do the last recursive call
1753 needed at this level, change it into iteration.
1754 This function is called enough to be worth it. */
1761 hash += hash_expr_1 (XEXP (x, i), 0, do_not_record_p);
1762 if (*do_not_record_p)
1766 else if (fmt[i] == 'E')
1767 for (j = 0; j < XVECLEN (x, i); j++)
1769 hash += hash_expr_1 (XVECEXP (x, i, j), 0, do_not_record_p);
1770 if (*do_not_record_p)
1774 else if (fmt[i] == 's')
1775 hash += hash_string_1 (XSTR (x, i));
1776 else if (fmt[i] == 'i')
1777 hash += (unsigned int) XINT (x, i);
1785 /* Hash a set of register REGNO.
1787 Sets are hashed on the register that is set. This simplifies the PRE copy
1790 ??? May need to make things more elaborate. Later, as necessary. */
1793 hash_set (regno, hash_table_size)
1795 int hash_table_size;
1800 return hash % hash_table_size;
1803 /* Return non-zero if exp1 is equivalent to exp2.
1804 ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
1817 if (x == 0 || y == 0)
1820 code = GET_CODE (x);
1821 if (code != GET_CODE (y))
1824 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
1825 if (GET_MODE (x) != GET_MODE (y))
1835 return INTVAL (x) == INTVAL (y);
1838 return XEXP (x, 0) == XEXP (y, 0);
1841 return XSTR (x, 0) == XSTR (y, 0);
1844 return REGNO (x) == REGNO (y);
1847 /* Can't merge two expressions in different alias sets, since we can
1848 decide that the expression is transparent in a block when it isn't,
1849 due to it being set with the different alias set. */
1850 if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
1854 /* For commutative operations, check both orders. */
1862 return ((expr_equiv_p (XEXP (x, 0), XEXP (y, 0))
1863 && expr_equiv_p (XEXP (x, 1), XEXP (y, 1)))
1864 || (expr_equiv_p (XEXP (x, 0), XEXP (y, 1))
1865 && expr_equiv_p (XEXP (x, 1), XEXP (y, 0))));
1868 /* We don't use the generic code below because we want to
1869 disregard filename and line numbers. */
1871 /* A volatile asm isn't equivalent to any other. */
1872 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
1875 if (GET_MODE (x) != GET_MODE (y)
1876 || strcmp (ASM_OPERANDS_TEMPLATE (x), ASM_OPERANDS_TEMPLATE (y))
1877 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x),
1878 ASM_OPERANDS_OUTPUT_CONSTRAINT (y))
1879 || ASM_OPERANDS_OUTPUT_IDX (x) != ASM_OPERANDS_OUTPUT_IDX (y)
1880 || ASM_OPERANDS_INPUT_LENGTH (x) != ASM_OPERANDS_INPUT_LENGTH (y))
1883 if (ASM_OPERANDS_INPUT_LENGTH (x))
1885 for (i = ASM_OPERANDS_INPUT_LENGTH (x) - 1; i >= 0; i--)
1886 if (! expr_equiv_p (ASM_OPERANDS_INPUT (x, i),
1887 ASM_OPERANDS_INPUT (y, i))
1888 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x, i),
1889 ASM_OPERANDS_INPUT_CONSTRAINT (y, i)))
1899 /* Compare the elements. If any pair of corresponding elements
1900 fail to match, return 0 for the whole thing. */
1902 fmt = GET_RTX_FORMAT (code);
1903 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1908 if (! expr_equiv_p (XEXP (x, i), XEXP (y, i)))
1913 if (XVECLEN (x, i) != XVECLEN (y, i))
1915 for (j = 0; j < XVECLEN (x, i); j++)
1916 if (! expr_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
1921 if (strcmp (XSTR (x, i), XSTR (y, i)))
1926 if (XINT (x, i) != XINT (y, i))
1931 if (XWINT (x, i) != XWINT (y, i))
1946 /* Insert expression X in INSN in the hash table.
1947 If it is already present, record it as the last occurrence in INSN's
1950 MODE is the mode of the value X is being stored into.
1951 It is only used if X is a CONST_INT.
1953 ANTIC_P is non-zero if X is an anticipatable expression.
1954 AVAIL_P is non-zero if X is an available expression. */
1957 insert_expr_in_table (x, mode, insn, antic_p, avail_p)
1959 enum machine_mode mode;
1961 int antic_p, avail_p;
1963 int found, do_not_record_p;
1965 struct expr *cur_expr, *last_expr = NULL;
1966 struct occr *antic_occr, *avail_occr;
1967 struct occr *last_occr = NULL;
1969 hash = hash_expr (x, mode, &do_not_record_p, expr_hash_table_size);
1971 /* Do not insert expression in table if it contains volatile operands,
1972 or if hash_expr determines the expression is something we don't want
1973 to or can't handle. */
1974 if (do_not_record_p)
1977 cur_expr = expr_hash_table[hash];
1980 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
1982 /* If the expression isn't found, save a pointer to the end of
1984 last_expr = cur_expr;
1985 cur_expr = cur_expr->next_same_hash;
1990 cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr));
1991 bytes_used += sizeof (struct expr);
1992 if (expr_hash_table[hash] == NULL)
1993 /* This is the first pattern that hashed to this index. */
1994 expr_hash_table[hash] = cur_expr;
1996 /* Add EXPR to end of this hash chain. */
1997 last_expr->next_same_hash = cur_expr;
1999 /* Set the fields of the expr element. */
2001 cur_expr->bitmap_index = n_exprs++;
2002 cur_expr->next_same_hash = NULL;
2003 cur_expr->antic_occr = NULL;
2004 cur_expr->avail_occr = NULL;
2007 /* Now record the occurrence(s). */
2010 antic_occr = cur_expr->antic_occr;
2012 /* Search for another occurrence in the same basic block. */
2013 while (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn))
2015 /* If an occurrence isn't found, save a pointer to the end of
2017 last_occr = antic_occr;
2018 antic_occr = antic_occr->next;
2022 /* Found another instance of the expression in the same basic block.
2023 Prefer the currently recorded one. We want the first one in the
2024 block and the block is scanned from start to end. */
2025 ; /* nothing to do */
2028 /* First occurrence of this expression in this basic block. */
2029 antic_occr = (struct occr *) gcse_alloc (sizeof (struct occr));
2030 bytes_used += sizeof (struct occr);
2031 /* First occurrence of this expression in any block? */
2032 if (cur_expr->antic_occr == NULL)
2033 cur_expr->antic_occr = antic_occr;
2035 last_occr->next = antic_occr;
2037 antic_occr->insn = insn;
2038 antic_occr->next = NULL;
2044 avail_occr = cur_expr->avail_occr;
2046 /* Search for another occurrence in the same basic block. */
2047 while (avail_occr && BLOCK_NUM (avail_occr->insn) != BLOCK_NUM (insn))
2049 /* If an occurrence isn't found, save a pointer to the end of
2051 last_occr = avail_occr;
2052 avail_occr = avail_occr->next;
2056 /* Found another instance of the expression in the same basic block.
2057 Prefer this occurrence to the currently recorded one. We want
2058 the last one in the block and the block is scanned from start
2060 avail_occr->insn = insn;
2063 /* First occurrence of this expression in this basic block. */
2064 avail_occr = (struct occr *) gcse_alloc (sizeof (struct occr));
2065 bytes_used += sizeof (struct occr);
2067 /* First occurrence of this expression in any block? */
2068 if (cur_expr->avail_occr == NULL)
2069 cur_expr->avail_occr = avail_occr;
2071 last_occr->next = avail_occr;
2073 avail_occr->insn = insn;
2074 avail_occr->next = NULL;
2079 /* Insert pattern X in INSN in the hash table.
2080 X is a SET of a reg to either another reg or a constant.
2081 If it is already present, record it as the last occurrence in INSN's
2085 insert_set_in_table (x, insn)
2091 struct expr *cur_expr, *last_expr = NULL;
2092 struct occr *cur_occr, *last_occr = NULL;
2094 if (GET_CODE (x) != SET
2095 || GET_CODE (SET_DEST (x)) != REG)
2098 hash = hash_set (REGNO (SET_DEST (x)), set_hash_table_size);
2100 cur_expr = set_hash_table[hash];
2103 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
2105 /* If the expression isn't found, save a pointer to the end of
2107 last_expr = cur_expr;
2108 cur_expr = cur_expr->next_same_hash;
2113 cur_expr = (struct expr *) gcse_alloc (sizeof (struct expr));
2114 bytes_used += sizeof (struct expr);
2115 if (set_hash_table[hash] == NULL)
2116 /* This is the first pattern that hashed to this index. */
2117 set_hash_table[hash] = cur_expr;
2119 /* Add EXPR to end of this hash chain. */
2120 last_expr->next_same_hash = cur_expr;
2122 /* Set the fields of the expr element.
2123 We must copy X because it can be modified when copy propagation is
2124 performed on its operands. */
2125 cur_expr->expr = copy_rtx (x);
2126 cur_expr->bitmap_index = n_sets++;
2127 cur_expr->next_same_hash = NULL;
2128 cur_expr->antic_occr = NULL;
2129 cur_expr->avail_occr = NULL;
2132 /* Now record the occurrence. */
2133 cur_occr = cur_expr->avail_occr;
2135 /* Search for another occurrence in the same basic block. */
2136 while (cur_occr && BLOCK_NUM (cur_occr->insn) != BLOCK_NUM (insn))
2138 /* If an occurrence isn't found, save a pointer to the end of
2140 last_occr = cur_occr;
2141 cur_occr = cur_occr->next;
2145 /* Found another instance of the expression in the same basic block.
2146 Prefer this occurrence to the currently recorded one. We want the
2147 last one in the block and the block is scanned from start to end. */
2148 cur_occr->insn = insn;
2151 /* First occurrence of this expression in this basic block. */
2152 cur_occr = (struct occr *) gcse_alloc (sizeof (struct occr));
2153 bytes_used += sizeof (struct occr);
2155 /* First occurrence of this expression in any block? */
2156 if (cur_expr->avail_occr == NULL)
2157 cur_expr->avail_occr = cur_occr;
2159 last_occr->next = cur_occr;
2161 cur_occr->insn = insn;
2162 cur_occr->next = NULL;
2166 /* Scan pattern PAT of INSN and add an entry to the hash table. If SET_P is
2167 non-zero, this is for the assignment hash table, otherwise it is for the
2168 expression hash table. */
2171 hash_scan_set (pat, insn, set_p)
2175 rtx src = SET_SRC (pat);
2176 rtx dest = SET_DEST (pat);
2179 if (GET_CODE (src) == CALL)
2180 hash_scan_call (src, insn);
2182 else if (GET_CODE (dest) == REG)
2184 unsigned int regno = REGNO (dest);
2187 /* If this is a single set and we are doing constant propagation,
2188 see if a REG_NOTE shows this equivalent to a constant. */
2189 if (set_p && (note = find_reg_equal_equiv_note (insn)) != 0
2190 && CONSTANT_P (XEXP (note, 0)))
2191 src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src);
2193 /* Only record sets of pseudo-regs in the hash table. */
2195 && regno >= FIRST_PSEUDO_REGISTER
2196 /* Don't GCSE something if we can't do a reg/reg copy. */
2197 && can_copy_p [GET_MODE (dest)]
2198 /* GCSE commonly inserts instruction after the insn. We can't
2199 do that easily for EH_REGION notes so disable GCSE on these
2201 && !find_reg_note (insn, REG_EH_REGION, NULL_RTX)
2202 /* Is SET_SRC something we want to gcse? */
2203 && want_to_gcse_p (src)
2204 /* Don't CSE a nop. */
2205 && ! set_noop_p (pat)
2206 /* Don't GCSE if it has attached REG_EQUIV note.
2207 At this point this only function parameters should have
2208 REG_EQUIV notes and if the argument slot is used somewhere
2209 explicitly, it means address of parameter has been taken,
2210 so we should not extend the lifetime of the pseudo. */
2211 && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
2212 || GET_CODE (XEXP (note, 0)) != MEM))
2214 /* An expression is not anticipatable if its operands are
2215 modified before this insn or if this is not the only SET in
2217 int antic_p = oprs_anticipatable_p (src, insn) && single_set (insn);
2218 /* An expression is not available if its operands are
2219 subsequently modified, including this insn. It's also not
2220 available if this is a branch, because we can't insert
2221 a set after the branch. */
2222 int avail_p = (oprs_available_p (src, insn)
2223 && ! JUMP_P (insn));
2225 insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p);
2228 /* Record sets for constant/copy propagation. */
2230 && regno >= FIRST_PSEUDO_REGISTER
2231 && ((GET_CODE (src) == REG
2232 && REGNO (src) >= FIRST_PSEUDO_REGISTER
2233 && can_copy_p [GET_MODE (dest)]
2234 && REGNO (src) != regno)
2235 || CONSTANT_P (src))
2236 /* A copy is not available if its src or dest is subsequently
2237 modified. Here we want to search from INSN+1 on, but
2238 oprs_available_p searches from INSN on. */
2239 && (insn == BLOCK_END (BLOCK_NUM (insn))
2240 || ((tmp = next_nonnote_insn (insn)) != NULL_RTX
2241 && oprs_available_p (pat, tmp))))
2242 insert_set_in_table (pat, insn);
2247 hash_scan_clobber (x, insn)
2248 rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED;
2250 /* Currently nothing to do. */
2254 hash_scan_call (x, insn)
2255 rtx x ATTRIBUTE_UNUSED, insn ATTRIBUTE_UNUSED;
2257 /* Currently nothing to do. */
2260 /* Process INSN and add hash table entries as appropriate.
2262 Only available expressions that set a single pseudo-reg are recorded.
2264 Single sets in a PARALLEL could be handled, but it's an extra complication
2265 that isn't dealt with right now. The trick is handling the CLOBBERs that
2266 are also in the PARALLEL. Later.
2268 If SET_P is non-zero, this is for the assignment hash table,
2269 otherwise it is for the expression hash table.
2270 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
2271 not record any expressions. */
2274 hash_scan_insn (insn, set_p, in_libcall_block)
2277 int in_libcall_block;
2279 rtx pat = PATTERN (insn);
2282 if (in_libcall_block)
2285 /* Pick out the sets of INSN and for other forms of instructions record
2286 what's been modified. */
2288 if (GET_CODE (pat) == SET)
2289 hash_scan_set (pat, insn, set_p);
2290 else if (GET_CODE (pat) == PARALLEL)
2291 for (i = 0; i < XVECLEN (pat, 0); i++)
2293 rtx x = XVECEXP (pat, 0, i);
2295 if (GET_CODE (x) == SET)
2296 hash_scan_set (x, insn, set_p);
2297 else if (GET_CODE (x) == CLOBBER)
2298 hash_scan_clobber (x, insn);
2299 else if (GET_CODE (x) == CALL)
2300 hash_scan_call (x, insn);
2303 else if (GET_CODE (pat) == CLOBBER)
2304 hash_scan_clobber (pat, insn);
2305 else if (GET_CODE (pat) == CALL)
2306 hash_scan_call (pat, insn);
2310 dump_hash_table (file, name, table, table_size, total_size)
2313 struct expr **table;
2314 int table_size, total_size;
2317 /* Flattened out table, so it's printed in proper order. */
2318 struct expr **flat_table;
2319 unsigned int *hash_val;
2323 = (struct expr **) xcalloc (total_size, sizeof (struct expr *));
2324 hash_val = (unsigned int *) xmalloc (total_size * sizeof (unsigned int));
2326 for (i = 0; i < table_size; i++)
2327 for (expr = table[i]; expr != NULL; expr = expr->next_same_hash)
2329 flat_table[expr->bitmap_index] = expr;
2330 hash_val[expr->bitmap_index] = i;
2333 fprintf (file, "%s hash table (%d buckets, %d entries)\n",
2334 name, table_size, total_size);
2336 for (i = 0; i < total_size; i++)
2337 if (flat_table[i] != 0)
2339 expr = flat_table[i];
2340 fprintf (file, "Index %d (hash value %d)\n ",
2341 expr->bitmap_index, hash_val[i]);
2342 print_rtl (file, expr->expr);
2343 fprintf (file, "\n");
2346 fprintf (file, "\n");
2352 /* Record register first/last/block set information for REGNO in INSN.
2354 first_set records the first place in the block where the register
2355 is set and is used to compute "anticipatability".
2357 last_set records the last place in the block where the register
2358 is set and is used to compute "availability".
2360 last_bb records the block for which first_set and last_set are
2361 valid, as a quick test to invalidate them.
2363 reg_set_in_block records whether the register is set in the block
2364 and is used to compute "transparency". */
2367 record_last_reg_set_info (insn, regno)
2371 struct reg_avail_info *info = ®_avail_info[regno];
2372 int cuid = INSN_CUID (insn);
2374 info->last_set = cuid;
2375 if (info->last_bb != current_bb)
2377 info->last_bb = current_bb;
2378 info->first_set = cuid;
2379 SET_BIT (reg_set_in_block[current_bb->index], regno);
2384 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
2385 Note we store a pair of elements in the list, so they have to be
2386 taken off pairwise. */
2389 canon_list_insert (dest, unused1, v_insn)
2390 rtx dest ATTRIBUTE_UNUSED;
2391 rtx unused1 ATTRIBUTE_UNUSED;
2394 rtx dest_addr, insn;
2397 while (GET_CODE (dest) == SUBREG
2398 || GET_CODE (dest) == ZERO_EXTRACT
2399 || GET_CODE (dest) == SIGN_EXTRACT
2400 || GET_CODE (dest) == STRICT_LOW_PART)
2401 dest = XEXP (dest, 0);
2403 /* If DEST is not a MEM, then it will not conflict with a load. Note
2404 that function calls are assumed to clobber memory, but are handled
2407 if (GET_CODE (dest) != MEM)
2410 dest_addr = get_addr (XEXP (dest, 0));
2411 dest_addr = canon_rtx (dest_addr);
2412 insn = (rtx) v_insn;
2413 bb = BLOCK_NUM (insn);
2415 canon_modify_mem_list[bb] =
2416 alloc_EXPR_LIST (VOIDmode, dest_addr, canon_modify_mem_list[bb]);
2417 canon_modify_mem_list[bb] =
2418 alloc_EXPR_LIST (VOIDmode, dest, canon_modify_mem_list[bb]);
2419 bitmap_set_bit (canon_modify_mem_list_set, bb);
2422 /* Record memory modification information for INSN. We do not actually care
2423 about the memory location(s) that are set, or even how they are set (consider
2424 a CALL_INSN). We merely need to record which insns modify memory. */
2427 record_last_mem_set_info (insn)
2430 int bb = BLOCK_NUM (insn);
2432 /* load_killed_in_block_p will handle the case of calls clobbering
2434 modify_mem_list[bb] = alloc_INSN_LIST (insn, modify_mem_list[bb]);
2435 bitmap_set_bit (modify_mem_list_set, bb);
2437 if (GET_CODE (insn) == CALL_INSN)
2439 /* Note that traversals of this loop (other than for free-ing)
2440 will break after encountering a CALL_INSN. So, there's no
2441 need to insert a pair of items, as canon_list_insert does. */
2442 canon_modify_mem_list[bb] =
2443 alloc_INSN_LIST (insn, canon_modify_mem_list[bb]);
2444 bitmap_set_bit (canon_modify_mem_list_set, bb);
2447 note_stores (PATTERN (insn), canon_list_insert, (void*) insn);
2450 /* Called from compute_hash_table via note_stores to handle one
2451 SET or CLOBBER in an insn. DATA is really the instruction in which
2452 the SET is taking place. */
2455 record_last_set_info (dest, setter, data)
2456 rtx dest, setter ATTRIBUTE_UNUSED;
2459 rtx last_set_insn = (rtx) data;
2461 if (GET_CODE (dest) == SUBREG)
2462 dest = SUBREG_REG (dest);
2464 if (GET_CODE (dest) == REG)
2465 record_last_reg_set_info (last_set_insn, REGNO (dest));
2466 else if (GET_CODE (dest) == MEM
2467 /* Ignore pushes, they clobber nothing. */
2468 && ! push_operand (dest, GET_MODE (dest)))
2469 record_last_mem_set_info (last_set_insn);
2472 /* Top level function to create an expression or assignment hash table.
2474 Expression entries are placed in the hash table if
2475 - they are of the form (set (pseudo-reg) src),
2476 - src is something we want to perform GCSE on,
2477 - none of the operands are subsequently modified in the block
2479 Assignment entries are placed in the hash table if
2480 - they are of the form (set (pseudo-reg) src),
2481 - src is something we want to perform const/copy propagation on,
2482 - none of the operands or target are subsequently modified in the block
2484 Currently src must be a pseudo-reg or a const_int.
2486 F is the first insn.
2487 SET_P is non-zero for computing the assignment hash table. */
2490 compute_hash_table (set_p)
2495 /* While we compute the hash table we also compute a bit array of which
2496 registers are set in which blocks.
2497 ??? This isn't needed during const/copy propagation, but it's cheap to
2499 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
2501 /* re-Cache any INSN_LIST nodes we have allocated. */
2502 clear_modify_mem_tables ();
2503 /* Some working arrays used to track first and last set in each block. */
2504 reg_avail_info = (struct reg_avail_info*)
2505 gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
2507 for (i = 0; i < max_gcse_regno; ++i)
2508 reg_avail_info[i].last_bb = NULL;
2510 FOR_EACH_BB (current_bb)
2514 int in_libcall_block;
2516 /* First pass over the instructions records information used to
2517 determine when registers and memory are first and last set.
2518 ??? hard-reg reg_set_in_block computation
2519 could be moved to compute_sets since they currently don't change. */
2521 for (insn = current_bb->head;
2522 insn && insn != NEXT_INSN (current_bb->end);
2523 insn = NEXT_INSN (insn))
2525 if (! INSN_P (insn))
2528 if (GET_CODE (insn) == CALL_INSN)
2530 bool clobbers_all = false;
2531 #ifdef NON_SAVING_SETJMP
2532 if (NON_SAVING_SETJMP
2533 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
2534 clobbers_all = true;
2537 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2539 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2540 record_last_reg_set_info (insn, regno);
2545 note_stores (PATTERN (insn), record_last_set_info, insn);
2548 /* The next pass builds the hash table. */
2550 for (insn = current_bb->head, in_libcall_block = 0;
2551 insn && insn != NEXT_INSN (current_bb->end);
2552 insn = NEXT_INSN (insn))
2555 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2556 in_libcall_block = 1;
2557 else if (set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2558 in_libcall_block = 0;
2559 hash_scan_insn (insn, set_p, in_libcall_block);
2560 if (!set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2561 in_libcall_block = 0;
2565 free (reg_avail_info);
2566 reg_avail_info = NULL;
2569 /* Allocate space for the set hash table.
2570 N_INSNS is the number of instructions in the function.
2571 It is used to determine the number of buckets to use. */
2574 alloc_set_hash_table (n_insns)
2579 set_hash_table_size = n_insns / 4;
2580 if (set_hash_table_size < 11)
2581 set_hash_table_size = 11;
2583 /* Attempt to maintain efficient use of hash table.
2584 Making it an odd number is simplest for now.
2585 ??? Later take some measurements. */
2586 set_hash_table_size |= 1;
2587 n = set_hash_table_size * sizeof (struct expr *);
2588 set_hash_table = (struct expr **) gmalloc (n);
2591 /* Free things allocated by alloc_set_hash_table. */
2594 free_set_hash_table ()
2596 free (set_hash_table);
2599 /* Compute the hash table for doing copy/const propagation. */
2602 compute_set_hash_table ()
2604 /* Initialize count of number of entries in hash table. */
2606 memset ((char *) set_hash_table, 0,
2607 set_hash_table_size * sizeof (struct expr *));
2609 compute_hash_table (1);
2612 /* Allocate space for the expression hash table.
2613 N_INSNS is the number of instructions in the function.
2614 It is used to determine the number of buckets to use. */
2617 alloc_expr_hash_table (n_insns)
2618 unsigned int n_insns;
2622 expr_hash_table_size = n_insns / 2;
2623 /* Make sure the amount is usable. */
2624 if (expr_hash_table_size < 11)
2625 expr_hash_table_size = 11;
2627 /* Attempt to maintain efficient use of hash table.
2628 Making it an odd number is simplest for now.
2629 ??? Later take some measurements. */
2630 expr_hash_table_size |= 1;
2631 n = expr_hash_table_size * sizeof (struct expr *);
2632 expr_hash_table = (struct expr **) gmalloc (n);
2635 /* Free things allocated by alloc_expr_hash_table. */
2638 free_expr_hash_table ()
2640 free (expr_hash_table);
2643 /* Compute the hash table for doing GCSE. */
2646 compute_expr_hash_table ()
2648 /* Initialize count of number of entries in hash table. */
2650 memset ((char *) expr_hash_table, 0,
2651 expr_hash_table_size * sizeof (struct expr *));
2653 compute_hash_table (0);
2656 /* Expression tracking support. */
2658 /* Lookup pattern PAT in the expression table.
2659 The result is a pointer to the table entry, or NULL if not found. */
2661 static struct expr *
2665 int do_not_record_p;
2666 unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p,
2667 expr_hash_table_size);
2670 if (do_not_record_p)
2673 expr = expr_hash_table[hash];
2675 while (expr && ! expr_equiv_p (expr->expr, pat))
2676 expr = expr->next_same_hash;
2681 /* Lookup REGNO in the set table. If PAT is non-NULL look for the entry that
2682 matches it, otherwise return the first entry for REGNO. The result is a
2683 pointer to the table entry, or NULL if not found. */
2685 static struct expr *
2686 lookup_set (regno, pat)
2690 unsigned int hash = hash_set (regno, set_hash_table_size);
2693 expr = set_hash_table[hash];
2697 while (expr && ! expr_equiv_p (expr->expr, pat))
2698 expr = expr->next_same_hash;
2702 while (expr && REGNO (SET_DEST (expr->expr)) != regno)
2703 expr = expr->next_same_hash;
2709 /* Return the next entry for REGNO in list EXPR. */
2711 static struct expr *
2712 next_set (regno, expr)
2717 expr = expr->next_same_hash;
2718 while (expr && REGNO (SET_DEST (expr->expr)) != regno);
2723 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2724 types may be mixed. */
2727 free_insn_expr_list_list (listp)
2732 for (list = *listp; list ; list = next)
2734 next = XEXP (list, 1);
2735 if (GET_CODE (list) == EXPR_LIST)
2736 free_EXPR_LIST_node (list);
2738 free_INSN_LIST_node (list);
2744 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2746 clear_modify_mem_tables ()
2750 EXECUTE_IF_SET_IN_BITMAP
2751 (modify_mem_list_set, 0, i, free_INSN_LIST_list (modify_mem_list + i));
2752 bitmap_clear (modify_mem_list_set);
2754 EXECUTE_IF_SET_IN_BITMAP
2755 (canon_modify_mem_list_set, 0, i,
2756 free_insn_expr_list_list (canon_modify_mem_list + i));
2757 bitmap_clear (canon_modify_mem_list_set);
2760 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2763 free_modify_mem_tables ()
2765 clear_modify_mem_tables ();
2766 free (modify_mem_list);
2767 free (canon_modify_mem_list);
2768 modify_mem_list = 0;
2769 canon_modify_mem_list = 0;
2772 /* Reset tables used to keep track of what's still available [since the
2773 start of the block]. */
2776 reset_opr_set_tables ()
2778 /* Maintain a bitmap of which regs have been set since beginning of
2780 CLEAR_REG_SET (reg_set_bitmap);
2782 /* Also keep a record of the last instruction to modify memory.
2783 For now this is very trivial, we only record whether any memory
2784 location has been modified. */
2785 clear_modify_mem_tables ();
2788 /* Return non-zero if the operands of X are not set before INSN in
2789 INSN's basic block. */
2792 oprs_not_set_p (x, insn)
2802 code = GET_CODE (x);
2818 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn),
2819 INSN_CUID (insn), x, 0))
2822 return oprs_not_set_p (XEXP (x, 0), insn);
2825 return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x));
2831 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2835 /* If we are about to do the last recursive call
2836 needed at this level, change it into iteration.
2837 This function is called enough to be worth it. */
2839 return oprs_not_set_p (XEXP (x, i), insn);
2841 if (! oprs_not_set_p (XEXP (x, i), insn))
2844 else if (fmt[i] == 'E')
2845 for (j = 0; j < XVECLEN (x, i); j++)
2846 if (! oprs_not_set_p (XVECEXP (x, i, j), insn))
2853 /* Mark things set by a CALL. */
2859 if (! CONST_OR_PURE_CALL_P (insn))
2860 record_last_mem_set_info (insn);
2863 /* Mark things set by a SET. */
2866 mark_set (pat, insn)
2869 rtx dest = SET_DEST (pat);
2871 while (GET_CODE (dest) == SUBREG
2872 || GET_CODE (dest) == ZERO_EXTRACT
2873 || GET_CODE (dest) == SIGN_EXTRACT
2874 || GET_CODE (dest) == STRICT_LOW_PART)
2875 dest = XEXP (dest, 0);
2877 if (GET_CODE (dest) == REG)
2878 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (dest));
2879 else if (GET_CODE (dest) == MEM)
2880 record_last_mem_set_info (insn);
2882 if (GET_CODE (SET_SRC (pat)) == CALL)
2886 /* Record things set by a CLOBBER. */
2889 mark_clobber (pat, insn)
2892 rtx clob = XEXP (pat, 0);
2894 while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART)
2895 clob = XEXP (clob, 0);
2897 if (GET_CODE (clob) == REG)
2898 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (clob));
2900 record_last_mem_set_info (insn);
2903 /* Record things set by INSN.
2904 This data is used by oprs_not_set_p. */
2907 mark_oprs_set (insn)
2910 rtx pat = PATTERN (insn);
2913 if (GET_CODE (pat) == SET)
2914 mark_set (pat, insn);
2915 else if (GET_CODE (pat) == PARALLEL)
2916 for (i = 0; i < XVECLEN (pat, 0); i++)
2918 rtx x = XVECEXP (pat, 0, i);
2920 if (GET_CODE (x) == SET)
2922 else if (GET_CODE (x) == CLOBBER)
2923 mark_clobber (x, insn);
2924 else if (GET_CODE (x) == CALL)
2928 else if (GET_CODE (pat) == CLOBBER)
2929 mark_clobber (pat, insn);
2930 else if (GET_CODE (pat) == CALL)
2935 /* Classic GCSE reaching definition support. */
2937 /* Allocate reaching def variables. */
2940 alloc_rd_mem (n_blocks, n_insns)
2941 int n_blocks, n_insns;
2943 rd_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
2944 sbitmap_vector_zero (rd_kill, n_blocks);
2946 rd_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
2947 sbitmap_vector_zero (rd_gen, n_blocks);
2949 reaching_defs = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
2950 sbitmap_vector_zero (reaching_defs, n_blocks);
2952 rd_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_insns);
2953 sbitmap_vector_zero (rd_out, n_blocks);
2956 /* Free reaching def variables. */
2961 sbitmap_vector_free (rd_kill);
2962 sbitmap_vector_free (rd_gen);
2963 sbitmap_vector_free (reaching_defs);
2964 sbitmap_vector_free (rd_out);
2967 /* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
2970 handle_rd_kill_set (insn, regno, bb)
2975 struct reg_set *this_reg;
2977 for (this_reg = reg_set_table[regno]; this_reg; this_reg = this_reg ->next)
2978 if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn))
2979 SET_BIT (rd_kill[bb->index], INSN_CUID (this_reg->insn));
2982 /* Compute the set of kill's for reaching definitions. */
2993 For each set bit in `gen' of the block (i.e each insn which
2994 generates a definition in the block)
2995 Call the reg set by the insn corresponding to that bit regx
2996 Look at the linked list starting at reg_set_table[regx]
2997 For each setting of regx in the linked list, which is not in
2999 Set the bit in `kill' corresponding to that insn. */
3001 for (cuid = 0; cuid < max_cuid; cuid++)
3002 if (TEST_BIT (rd_gen[bb->index], cuid))
3004 rtx insn = CUID_INSN (cuid);
3005 rtx pat = PATTERN (insn);
3007 if (GET_CODE (insn) == CALL_INSN)
3009 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
3010 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
3011 handle_rd_kill_set (insn, regno, bb);
3014 if (GET_CODE (pat) == PARALLEL)
3016 for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
3018 enum rtx_code code = GET_CODE (XVECEXP (pat, 0, i));
3020 if ((code == SET || code == CLOBBER)
3021 && GET_CODE (XEXP (XVECEXP (pat, 0, i), 0)) == REG)
3022 handle_rd_kill_set (insn,
3023 REGNO (XEXP (XVECEXP (pat, 0, i), 0)),
3027 else if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == REG)
3028 /* Each setting of this register outside of this block
3029 must be marked in the set of kills in this block. */
3030 handle_rd_kill_set (insn, REGNO (SET_DEST (pat)), bb);
3034 /* Compute the reaching definitions as in
3035 Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
3036 Chapter 10. It is the same algorithm as used for computing available
3037 expressions but applied to the gens and kills of reaching definitions. */
3042 int changed, passes;
3046 sbitmap_copy (rd_out[bb->index] /*dst*/, rd_gen[bb->index] /*src*/);
3055 sbitmap_union_of_preds (reaching_defs[bb->index], rd_out, bb->index);
3056 changed |= sbitmap_union_of_diff_cg (rd_out[bb->index], rd_gen[bb->index],
3057 reaching_defs[bb->index], rd_kill[bb->index]);
3063 fprintf (gcse_file, "reaching def computation: %d passes\n", passes);
3066 /* Classic GCSE available expression support. */
3068 /* Allocate memory for available expression computation. */
3071 alloc_avail_expr_mem (n_blocks, n_exprs)
3072 int n_blocks, n_exprs;
3074 ae_kill = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
3075 sbitmap_vector_zero (ae_kill, n_blocks);
3077 ae_gen = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
3078 sbitmap_vector_zero (ae_gen, n_blocks);
3080 ae_in = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
3081 sbitmap_vector_zero (ae_in, n_blocks);
3083 ae_out = (sbitmap *) sbitmap_vector_alloc (n_blocks, n_exprs);
3084 sbitmap_vector_zero (ae_out, n_blocks);
3088 free_avail_expr_mem ()
3090 sbitmap_vector_free (ae_kill);
3091 sbitmap_vector_free (ae_gen);
3092 sbitmap_vector_free (ae_in);
3093 sbitmap_vector_free (ae_out);
3096 /* Compute the set of available expressions generated in each basic block. */
3105 /* For each recorded occurrence of each expression, set ae_gen[bb][expr].
3106 This is all we have to do because an expression is not recorded if it
3107 is not available, and the only expressions we want to work with are the
3108 ones that are recorded. */
3109 for (i = 0; i < expr_hash_table_size; i++)
3110 for (expr = expr_hash_table[i]; expr != 0; expr = expr->next_same_hash)
3111 for (occr = expr->avail_occr; occr != 0; occr = occr->next)
3112 SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index);
3115 /* Return non-zero if expression X is killed in BB. */
3118 expr_killed_p (x, bb)
3129 code = GET_CODE (x);
3133 return TEST_BIT (reg_set_in_block[bb->index], REGNO (x));
3136 if (load_killed_in_block_p (bb, get_max_uid () + 1, x, 0))
3139 return expr_killed_p (XEXP (x, 0), bb);
3157 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3161 /* If we are about to do the last recursive call
3162 needed at this level, change it into iteration.
3163 This function is called enough to be worth it. */
3165 return expr_killed_p (XEXP (x, i), bb);
3166 else if (expr_killed_p (XEXP (x, i), bb))
3169 else if (fmt[i] == 'E')
3170 for (j = 0; j < XVECLEN (x, i); j++)
3171 if (expr_killed_p (XVECEXP (x, i, j), bb))
3178 /* Compute the set of available expressions killed in each basic block. */
3181 compute_ae_kill (ae_gen, ae_kill)
3182 sbitmap *ae_gen, *ae_kill;
3189 for (i = 0; i < expr_hash_table_size; i++)
3190 for (expr = expr_hash_table[i]; expr; expr = expr->next_same_hash)
3192 /* Skip EXPR if generated in this block. */
3193 if (TEST_BIT (ae_gen[bb->index], expr->bitmap_index))
3196 if (expr_killed_p (expr->expr, bb))
3197 SET_BIT (ae_kill[bb->index], expr->bitmap_index);
3201 /* Actually perform the Classic GCSE optimizations. */
3203 /* Return non-zero if occurrence OCCR of expression EXPR reaches block BB.
3205 CHECK_SELF_LOOP is non-zero if we should consider a block reaching itself
3206 as a positive reach. We want to do this when there are two computations
3207 of the expression in the block.
3209 VISITED is a pointer to a working buffer for tracking which BB's have
3210 been visited. It is NULL for the top-level call.
3212 We treat reaching expressions that go through blocks containing the same
3213 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3214 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3215 2 as not reaching. The intent is to improve the probability of finding
3216 only one reaching expression and to reduce register lifetimes by picking
3217 the closest such expression. */
3220 expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited)
3224 int check_self_loop;
3229 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
3231 basic_block pred_bb = pred->src;
3233 if (visited[pred_bb->index])
3234 /* This predecessor has already been visited. Nothing to do. */
3236 else if (pred_bb == bb)
3238 /* BB loops on itself. */
3240 && TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index)
3241 && BLOCK_NUM (occr->insn) == pred_bb->index)
3244 visited[pred_bb->index] = 1;
3247 /* Ignore this predecessor if it kills the expression. */
3248 else if (TEST_BIT (ae_kill[pred_bb->index], expr->bitmap_index))
3249 visited[pred_bb->index] = 1;
3251 /* Does this predecessor generate this expression? */
3252 else if (TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index))
3254 /* Is this the occurrence we're looking for?
3255 Note that there's only one generating occurrence per block
3256 so we just need to check the block number. */
3257 if (BLOCK_NUM (occr->insn) == pred_bb->index)
3260 visited[pred_bb->index] = 1;
3263 /* Neither gen nor kill. */
3266 visited[pred_bb->index] = 1;
3267 if (expr_reaches_here_p_work (occr, expr, pred_bb, check_self_loop,
3274 /* All paths have been checked. */
3278 /* This wrapper for expr_reaches_here_p_work() is to ensure that any
3279 memory allocated for that function is returned. */
3282 expr_reaches_here_p (occr, expr, bb, check_self_loop)
3286 int check_self_loop;
3289 char *visited = (char *) xcalloc (last_basic_block, 1);
3291 rval = expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited);
3297 /* Return the instruction that computes EXPR that reaches INSN's basic block.
3298 If there is more than one such instruction, return NULL.
3300 Called only by handle_avail_expr. */
3303 computing_insn (expr, insn)
3307 basic_block bb = BLOCK_FOR_INSN (insn);
3309 if (expr->avail_occr->next == NULL)
3311 if (BLOCK_FOR_INSN (expr->avail_occr->insn) == bb)
3312 /* The available expression is actually itself
3313 (i.e. a loop in the flow graph) so do nothing. */
3316 /* (FIXME) Case that we found a pattern that was created by
3317 a substitution that took place. */
3318 return expr->avail_occr->insn;
3322 /* Pattern is computed more than once.
3323 Search backwards from this insn to see how many of these
3324 computations actually reach this insn. */
3326 rtx insn_computes_expr = NULL;
3329 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
3331 if (BLOCK_FOR_INSN (occr->insn) == bb)
3333 /* The expression is generated in this block.
3334 The only time we care about this is when the expression
3335 is generated later in the block [and thus there's a loop].
3336 We let the normal cse pass handle the other cases. */
3337 if (INSN_CUID (insn) < INSN_CUID (occr->insn)
3338 && expr_reaches_here_p (occr, expr, bb, 1))
3344 insn_computes_expr = occr->insn;
3347 else if (expr_reaches_here_p (occr, expr, bb, 0))
3353 insn_computes_expr = occr->insn;
3357 if (insn_computes_expr == NULL)
3360 return insn_computes_expr;
3364 /* Return non-zero if the definition in DEF_INSN can reach INSN.
3365 Only called by can_disregard_other_sets. */
3368 def_reaches_here_p (insn, def_insn)
3373 if (TEST_BIT (reaching_defs[BLOCK_NUM (insn)], INSN_CUID (def_insn)))
3376 if (BLOCK_NUM (insn) == BLOCK_NUM (def_insn))
3378 if (INSN_CUID (def_insn) < INSN_CUID (insn))
3380 if (GET_CODE (PATTERN (def_insn)) == PARALLEL)
3382 else if (GET_CODE (PATTERN (def_insn)) == CLOBBER)
3383 reg = XEXP (PATTERN (def_insn), 0);
3384 else if (GET_CODE (PATTERN (def_insn)) == SET)
3385 reg = SET_DEST (PATTERN (def_insn));
3389 return ! reg_set_between_p (reg, NEXT_INSN (def_insn), insn);
3398 /* Return non-zero if *ADDR_THIS_REG can only have one value at INSN. The
3399 value returned is the number of definitions that reach INSN. Returning a
3400 value of zero means that [maybe] more than one definition reaches INSN and
3401 the caller can't perform whatever optimization it is trying. i.e. it is
3402 always safe to return zero. */
3405 can_disregard_other_sets (addr_this_reg, insn, for_combine)
3406 struct reg_set **addr_this_reg;
3410 int number_of_reaching_defs = 0;
3411 struct reg_set *this_reg;
3413 for (this_reg = *addr_this_reg; this_reg != 0; this_reg = this_reg->next)
3414 if (def_reaches_here_p (insn, this_reg->insn))
3416 number_of_reaching_defs++;
3417 /* Ignore parallels for now. */
3418 if (GET_CODE (PATTERN (this_reg->insn)) == PARALLEL)
3422 && (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER
3423 || ! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
3424 SET_SRC (PATTERN (insn)))))
3425 /* A setting of the reg to a different value reaches INSN. */
3428 if (number_of_reaching_defs > 1)
3430 /* If in this setting the value the register is being set to is
3431 equal to the previous value the register was set to and this
3432 setting reaches the insn we are trying to do the substitution
3433 on then we are ok. */
3434 if (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER)
3436 else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
3437 SET_SRC (PATTERN (insn))))
3441 *addr_this_reg = this_reg;
3444 return number_of_reaching_defs;
3447 /* Expression computed by insn is available and the substitution is legal,
3448 so try to perform the substitution.
3450 The result is non-zero if any changes were made. */
3453 handle_avail_expr (insn, expr)
3457 rtx pat, insn_computes_expr, expr_set;
3459 struct reg_set *this_reg;
3460 int found_setting, use_src;
3463 /* We only handle the case where one computation of the expression
3464 reaches this instruction. */
3465 insn_computes_expr = computing_insn (expr, insn);
3466 if (insn_computes_expr == NULL)
3468 expr_set = single_set (insn_computes_expr);
3475 /* At this point we know only one computation of EXPR outside of this
3476 block reaches this insn. Now try to find a register that the
3477 expression is computed into. */
3478 if (GET_CODE (SET_SRC (expr_set)) == REG)
3480 /* This is the case when the available expression that reaches
3481 here has already been handled as an available expression. */
3482 unsigned int regnum_for_replacing
3483 = REGNO (SET_SRC (expr_set));
3485 /* If the register was created by GCSE we can't use `reg_set_table',
3486 however we know it's set only once. */
3487 if (regnum_for_replacing >= max_gcse_regno
3488 /* If the register the expression is computed into is set only once,
3489 or only one set reaches this insn, we can use it. */
3490 || (((this_reg = reg_set_table[regnum_for_replacing]),
3491 this_reg->next == NULL)
3492 || can_disregard_other_sets (&this_reg, insn, 0)))
3501 unsigned int regnum_for_replacing
3502 = REGNO (SET_DEST (expr_set));
3504 /* This shouldn't happen. */
3505 if (regnum_for_replacing >= max_gcse_regno)
3508 this_reg = reg_set_table[regnum_for_replacing];
3510 /* If the register the expression is computed into is set only once,
3511 or only one set reaches this insn, use it. */
3512 if (this_reg->next == NULL
3513 || can_disregard_other_sets (&this_reg, insn, 0))
3519 pat = PATTERN (insn);
3521 to = SET_SRC (expr_set);
3523 to = SET_DEST (expr_set);
3524 changed = validate_change (insn, &SET_SRC (pat), to, 0);
3526 /* We should be able to ignore the return code from validate_change but
3527 to play it safe we check. */
3531 if (gcse_file != NULL)
3533 fprintf (gcse_file, "GCSE: Replacing the source in insn %d with",
3535 fprintf (gcse_file, " reg %d %s insn %d\n",
3536 REGNO (to), use_src ? "from" : "set in",
3537 INSN_UID (insn_computes_expr));
3542 /* The register that the expr is computed into is set more than once. */
3543 else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
3545 /* Insert an insn after insnx that copies the reg set in insnx
3546 into a new pseudo register call this new register REGN.
3547 From insnb until end of basic block or until REGB is set
3548 replace all uses of REGB with REGN. */
3551 to = gen_reg_rtx (GET_MODE (SET_DEST (expr_set)));
3553 /* Generate the new insn. */
3554 /* ??? If the change fails, we return 0, even though we created
3555 an insn. I think this is ok. */
3557 = emit_insn_after (gen_rtx_SET (VOIDmode, to,
3558 SET_DEST (expr_set)),
3559 insn_computes_expr);
3561 /* Keep register set table up to date. */
3562 record_one_set (REGNO (to), new_insn);
3564 gcse_create_count++;
3565 if (gcse_file != NULL)
3567 fprintf (gcse_file, "GCSE: Creating insn %d to copy value of reg %d",
3568 INSN_UID (NEXT_INSN (insn_computes_expr)),
3569 REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr)))));
3570 fprintf (gcse_file, ", computed in insn %d,\n",
3571 INSN_UID (insn_computes_expr));
3572 fprintf (gcse_file, " into newly allocated reg %d\n",
3576 pat = PATTERN (insn);
3578 /* Do register replacement for INSN. */
3579 changed = validate_change (insn, &SET_SRC (pat),
3581 (NEXT_INSN (insn_computes_expr))),
3584 /* We should be able to ignore the return code from validate_change but
3585 to play it safe we check. */
3589 if (gcse_file != NULL)
3592 "GCSE: Replacing the source in insn %d with reg %d ",
3594 REGNO (SET_DEST (PATTERN (NEXT_INSN
3595 (insn_computes_expr)))));
3596 fprintf (gcse_file, "set in insn %d\n",
3597 INSN_UID (insn_computes_expr));
3605 /* Perform classic GCSE. This is called by one_classic_gcse_pass after all
3606 the dataflow analysis has been done.
3608 The result is non-zero if a change was made. */
3617 /* Note we start at block 1. */
3619 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
3623 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
3625 /* Reset tables used to keep track of what's still valid [since the
3626 start of the block]. */
3627 reset_opr_set_tables ();
3629 for (insn = bb->head;
3630 insn != NULL && insn != NEXT_INSN (bb->end);
3631 insn = NEXT_INSN (insn))
3633 /* Is insn of form (set (pseudo-reg) ...)? */
3634 if (GET_CODE (insn) == INSN
3635 && GET_CODE (PATTERN (insn)) == SET
3636 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
3637 && REGNO (SET_DEST (PATTERN (insn))) >= FIRST_PSEUDO_REGISTER)
3639 rtx pat = PATTERN (insn);
3640 rtx src = SET_SRC (pat);
3643 if (want_to_gcse_p (src)
3644 /* Is the expression recorded? */
3645 && ((expr = lookup_expr (src)) != NULL)
3646 /* Is the expression available [at the start of the
3648 && TEST_BIT (ae_in[bb->index], expr->bitmap_index)
3649 /* Are the operands unchanged since the start of the
3651 && oprs_not_set_p (src, insn))
3652 changed |= handle_avail_expr (insn, expr);
3655 /* Keep track of everything modified by this insn. */
3656 /* ??? Need to be careful w.r.t. mods done to INSN. */
3658 mark_oprs_set (insn);
3665 /* Top level routine to perform one classic GCSE pass.
3667 Return non-zero if a change was made. */
3670 one_classic_gcse_pass (pass)
3675 gcse_subst_count = 0;
3676 gcse_create_count = 0;
3678 alloc_expr_hash_table (max_cuid);
3679 alloc_rd_mem (last_basic_block, max_cuid);
3680 compute_expr_hash_table ();
3682 dump_hash_table (gcse_file, "Expression", expr_hash_table,
3683 expr_hash_table_size, n_exprs);
3689 alloc_avail_expr_mem (last_basic_block, n_exprs);
3691 compute_ae_kill (ae_gen, ae_kill);
3692 compute_available (ae_gen, ae_kill, ae_out, ae_in);
3693 changed = classic_gcse ();
3694 free_avail_expr_mem ();
3698 free_expr_hash_table ();
3702 fprintf (gcse_file, "\n");
3703 fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
3704 current_function_name, pass, bytes_used, gcse_subst_count);
3705 fprintf (gcse_file, "%d insns created\n", gcse_create_count);
3711 /* Compute copy/constant propagation working variables. */
3713 /* Local properties of assignments. */
3714 static sbitmap *cprop_pavloc;
3715 static sbitmap *cprop_absaltered;
3717 /* Global properties of assignments (computed from the local properties). */
3718 static sbitmap *cprop_avin;
3719 static sbitmap *cprop_avout;
3721 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
3722 basic blocks. N_SETS is the number of sets. */
3725 alloc_cprop_mem (n_blocks, n_sets)
3726 int n_blocks, n_sets;
3728 cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
3729 cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
3731 cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
3732 cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
3735 /* Free vars used by copy/const propagation. */
3740 sbitmap_vector_free (cprop_pavloc);
3741 sbitmap_vector_free (cprop_absaltered);
3742 sbitmap_vector_free (cprop_avin);
3743 sbitmap_vector_free (cprop_avout);
3746 /* For each block, compute whether X is transparent. X is either an
3747 expression or an assignment [though we don't care which, for this context
3748 an assignment is treated as an expression]. For each block where an
3749 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
3753 compute_transp (x, indx, bmap, set_p)
3765 /* repeat is used to turn tail-recursion into iteration since GCC
3766 can't do it when there's no return value. */
3772 code = GET_CODE (x);
3778 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
3781 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
3782 SET_BIT (bmap[bb->index], indx);
3786 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
3787 SET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
3792 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
3795 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
3796 RESET_BIT (bmap[bb->index], indx);
3800 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
3801 RESET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
3810 rtx list_entry = canon_modify_mem_list[bb->index];
3814 rtx dest, dest_addr;
3816 if (GET_CODE (XEXP (list_entry, 0)) == CALL_INSN)
3819 SET_BIT (bmap[bb->index], indx);
3821 RESET_BIT (bmap[bb->index], indx);
3824 /* LIST_ENTRY must be an INSN of some kind that sets memory.
3825 Examine each hunk of memory that is modified. */
3827 dest = XEXP (list_entry, 0);
3828 list_entry = XEXP (list_entry, 1);
3829 dest_addr = XEXP (list_entry, 0);
3831 if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
3832 x, rtx_addr_varies_p))
3835 SET_BIT (bmap[bb->index], indx);
3837 RESET_BIT (bmap[bb->index], indx);
3840 list_entry = XEXP (list_entry, 1);
3863 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3867 /* If we are about to do the last recursive call
3868 needed at this level, change it into iteration.
3869 This function is called enough to be worth it. */
3876 compute_transp (XEXP (x, i), indx, bmap, set_p);
3878 else if (fmt[i] == 'E')
3879 for (j = 0; j < XVECLEN (x, i); j++)
3880 compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
3884 /* Top level routine to do the dataflow analysis needed by copy/const
3888 compute_cprop_data ()
3890 compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, 1);
3891 compute_available (cprop_pavloc, cprop_absaltered,
3892 cprop_avout, cprop_avin);
3895 /* Copy/constant propagation. */
3897 /* Maximum number of register uses in an insn that we handle. */
3900 /* Table of uses found in an insn.
3901 Allocated statically to avoid alloc/free complexity and overhead. */
3902 static struct reg_use reg_use_table[MAX_USES];
3904 /* Index into `reg_use_table' while building it. */
3905 static int reg_use_count;
3907 /* Set up a list of register numbers used in INSN. The found uses are stored
3908 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
3909 and contains the number of uses in the table upon exit.
3911 ??? If a register appears multiple times we will record it multiple times.
3912 This doesn't hurt anything but it will slow things down. */
3915 find_used_regs (xptr, data)
3917 void *data ATTRIBUTE_UNUSED;
3924 /* repeat is used to turn tail-recursion into iteration since GCC
3925 can't do it when there's no return value. */
3930 code = GET_CODE (x);
3933 if (reg_use_count == MAX_USES)
3936 reg_use_table[reg_use_count].reg_rtx = x;
3940 /* Recursively scan the operands of this expression. */
3942 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3946 /* If we are about to do the last recursive call
3947 needed at this level, change it into iteration.
3948 This function is called enough to be worth it. */
3955 find_used_regs (&XEXP (x, i), data);
3957 else if (fmt[i] == 'E')
3958 for (j = 0; j < XVECLEN (x, i); j++)
3959 find_used_regs (&XVECEXP (x, i, j), data);
3963 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
3964 Returns non-zero is successful. */
3967 try_replace_reg (from, to, insn)
3970 rtx note = find_reg_equal_equiv_note (insn);
3973 rtx set = single_set (insn);
3975 success = validate_replace_src (from, to, insn);
3977 /* If above failed and this is a single set, try to simplify the source of
3978 the set given our substitution. We could perhaps try this for multiple
3979 SETs, but it probably won't buy us anything. */
3980 if (!success && set != 0)
3982 src = simplify_replace_rtx (SET_SRC (set), from, to);
3984 if (!rtx_equal_p (src, SET_SRC (set))
3985 && validate_change (insn, &SET_SRC (set), src, 0))
3989 /* If we've failed to do replacement, have a single SET, and don't already
3990 have a note, add a REG_EQUAL note to not lose information. */
3991 if (!success && note == 0 && set != 0)
3992 note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
3994 /* If there is already a NOTE, update the expression in it with our
3997 XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to);
3999 /* REG_EQUAL may get simplified into register.
4000 We don't allow that. Remove that note. This code ought
4001 not to hapen, because previous code ought to syntetize
4002 reg-reg move, but be on the safe side. */
4003 if (note && REG_P (XEXP (note, 0)))
4004 remove_note (insn, note);
4009 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
4010 NULL no such set is found. */
4012 static struct expr *
4013 find_avail_set (regno, insn)
4017 /* SET1 contains the last set found that can be returned to the caller for
4018 use in a substitution. */
4019 struct expr *set1 = 0;
4021 /* Loops are not possible here. To get a loop we would need two sets
4022 available at the start of the block containing INSN. ie we would
4023 need two sets like this available at the start of the block:
4025 (set (reg X) (reg Y))
4026 (set (reg Y) (reg X))
4028 This can not happen since the set of (reg Y) would have killed the
4029 set of (reg X) making it unavailable at the start of this block. */
4033 struct expr *set = lookup_set (regno, NULL_RTX);
4035 /* Find a set that is available at the start of the block
4036 which contains INSN. */
4039 if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
4041 set = next_set (regno, set);
4044 /* If no available set was found we've reached the end of the
4045 (possibly empty) copy chain. */
4049 if (GET_CODE (set->expr) != SET)
4052 src = SET_SRC (set->expr);
4054 /* We know the set is available.
4055 Now check that SRC is ANTLOC (i.e. none of the source operands
4056 have changed since the start of the block).
4058 If the source operand changed, we may still use it for the next
4059 iteration of this loop, but we may not use it for substitutions. */
4061 if (CONSTANT_P (src) || oprs_not_set_p (src, insn))
4064 /* If the source of the set is anything except a register, then
4065 we have reached the end of the copy chain. */
4066 if (GET_CODE (src) != REG)
4069 /* Follow the copy chain, ie start another iteration of the loop
4070 and see if we have an available copy into SRC. */
4071 regno = REGNO (src);
4074 /* SET1 holds the last set that was available and anticipatable at
4079 /* Subroutine of cprop_insn that tries to propagate constants into
4080 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
4081 it is the instruction that immediately preceeds JUMP, and must be a
4082 single SET of a register. FROM is what we will try to replace,
4083 SRC is the constant we will try to substitute for it. Returns nonzero
4084 if a change was made. */
4087 cprop_jump (bb, setcc, jump, from, src)
4095 rtx set = pc_set (jump);
4097 /* First substitute in the INSN condition as the SET_SRC of the JUMP,
4098 then substitute that given values in this expanded JUMP. */
4100 new_set = simplify_replace_rtx (SET_SRC (set),
4101 SET_DEST (PATTERN (setcc)),
4102 SET_SRC (PATTERN (setcc)));
4106 new = simplify_replace_rtx (new_set, from, src);
4108 /* If no simplification can be made, then try the next
4110 if (rtx_equal_p (new, new_set))
4113 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
4118 if (! validate_change (jump, &SET_SRC (set), new, 0))
4121 /* If this has turned into an unconditional jump,
4122 then put a barrier after it so that the unreachable
4123 code will be deleted. */
4124 if (GET_CODE (SET_SRC (set)) == LABEL_REF)
4125 emit_barrier_after (jump);
4129 /* Delete the cc0 setter. */
4130 if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
4131 delete_insn (setcc);
4134 run_jump_opt_after_gcse = 1;
4137 if (gcse_file != NULL)
4140 "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
4141 REGNO (from), INSN_UID (jump));
4142 print_rtl (gcse_file, src);
4143 fprintf (gcse_file, "\n");
4145 purge_dead_edges (bb);
4150 /* Perform constant and copy propagation on INSN.
4151 The result is non-zero if a change was made. */
4154 cprop_insn (bb, insn, alter_jumps)
4159 struct reg_use *reg_used;
4167 note_uses (&PATTERN (insn), find_used_regs, NULL);
4169 note = find_reg_equal_equiv_note (insn);
4171 /* We may win even when propagating constants into notes. */
4173 find_used_regs (&XEXP (note, 0), NULL);
4175 for (reg_used = ®_use_table[0]; reg_use_count > 0;
4176 reg_used++, reg_use_count--)
4178 unsigned int regno = REGNO (reg_used->reg_rtx);
4182 /* Ignore registers created by GCSE.
4183 We do this because ... */
4184 if (regno >= max_gcse_regno)
4187 /* If the register has already been set in this block, there's
4188 nothing we can do. */
4189 if (! oprs_not_set_p (reg_used->reg_rtx, insn))
4192 /* Find an assignment that sets reg_used and is available
4193 at the start of the block. */
4194 set = find_avail_set (regno, insn);
4199 /* ??? We might be able to handle PARALLELs. Later. */
4200 if (GET_CODE (pat) != SET)
4203 src = SET_SRC (pat);
4205 /* Constant propagation. */
4206 if (CONSTANT_P (src))
4210 /* Check for reg or cc0 setting instructions followed by
4211 conditional branch instructions first. */
4213 && (sset = single_set (insn)) != NULL
4214 && any_condjump_p (NEXT_INSN (insn))
4215 && onlyjump_p (NEXT_INSN (insn)))
4217 rtx dest = SET_DEST (sset);
4218 if ((REG_P (dest) || CC0_P (dest))
4219 && cprop_jump (bb, insn, NEXT_INSN (insn),
4220 reg_used->reg_rtx, src))
4227 /* Handle normal insns next. */
4228 if (GET_CODE (insn) == INSN
4229 && try_replace_reg (reg_used->reg_rtx, src, insn))
4233 if (gcse_file != NULL)
4235 fprintf (gcse_file, "CONST-PROP: Replacing reg %d in ",
4237 fprintf (gcse_file, "insn %d with constant ",
4239 print_rtl (gcse_file, src);
4240 fprintf (gcse_file, "\n");
4243 /* The original insn setting reg_used may or may not now be
4244 deletable. We leave the deletion to flow. */
4247 /* Try to propagate a CONST_INT into a conditional jump.
4248 We're pretty specific about what we will handle in this
4249 code, we can extend this as necessary over time.
4251 Right now the insn in question must look like
4252 (set (pc) (if_then_else ...)) */
4253 else if (alter_jumps
4254 && any_condjump_p (insn)
4255 && onlyjump_p (insn))
4256 changed |= cprop_jump (bb, NULL, insn, reg_used->reg_rtx, src);
4259 else if (GET_CODE (src) == REG
4260 && REGNO (src) >= FIRST_PSEUDO_REGISTER
4261 && REGNO (src) != regno)
4263 if (try_replace_reg (reg_used->reg_rtx, src, insn))
4267 if (gcse_file != NULL)
4269 fprintf (gcse_file, "COPY-PROP: Replacing reg %d in insn %d",
4270 regno, INSN_UID (insn));
4271 fprintf (gcse_file, " with reg %d\n", REGNO (src));
4274 /* The original insn setting reg_used may or may not now be
4275 deletable. We leave the deletion to flow. */
4276 /* FIXME: If it turns out that the insn isn't deletable,
4277 then we may have unnecessarily extended register lifetimes
4278 and made things worse. */
4286 /* Forward propagate copies. This includes copies and constants. Return
4287 non-zero if a change was made. */
4297 /* Note we start at block 1. */
4298 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
4300 if (gcse_file != NULL)
4301 fprintf (gcse_file, "\n");
4306 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
4308 /* Reset tables used to keep track of what's still valid [since the
4309 start of the block]. */
4310 reset_opr_set_tables ();
4312 for (insn = bb->head;
4313 insn != NULL && insn != NEXT_INSN (bb->end);
4314 insn = NEXT_INSN (insn))
4317 changed |= cprop_insn (bb, insn, alter_jumps);
4319 /* Keep track of everything modified by this insn. */
4320 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
4321 call mark_oprs_set if we turned the insn into a NOTE. */
4322 if (GET_CODE (insn) != NOTE)
4323 mark_oprs_set (insn);
4327 if (gcse_file != NULL)
4328 fprintf (gcse_file, "\n");
4333 /* Perform one copy/constant propagation pass.
4334 F is the first insn in the function.
4335 PASS is the pass count. */
4338 one_cprop_pass (pass, alter_jumps)
4344 const_prop_count = 0;
4345 copy_prop_count = 0;
4347 alloc_set_hash_table (max_cuid);
4348 compute_set_hash_table ();
4350 dump_hash_table (gcse_file, "SET", set_hash_table, set_hash_table_size,
4354 alloc_cprop_mem (last_basic_block, n_sets);
4355 compute_cprop_data ();
4356 changed = cprop (alter_jumps);
4358 changed |= bypass_conditional_jumps ();
4362 free_set_hash_table ();
4366 fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, ",
4367 current_function_name, pass, bytes_used);
4368 fprintf (gcse_file, "%d const props, %d copy props\n\n",
4369 const_prop_count, copy_prop_count);
4375 /* Bypass conditional jumps. */
4377 /* Find a set of REGNO to a constant that is available at the end of basic
4378 block BB. Returns NULL if no such set is found. Based heavily upon
4381 static struct expr *
4382 find_bypass_set (regno, bb)
4386 struct expr *result = 0;
4391 struct expr *set = lookup_set (regno, NULL_RTX);
4395 if (TEST_BIT (cprop_avout[bb], set->bitmap_index))
4397 set = next_set (regno, set);
4403 if (GET_CODE (set->expr) != SET)
4406 src = SET_SRC (set->expr);
4407 if (CONSTANT_P (src))
4410 if (GET_CODE (src) != REG)
4413 regno = REGNO (src);
4419 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
4420 basic block BB which has more than one predecessor. If not NULL, SETCC
4421 is the first instruction of BB, which is immediately followed by JUMP_INSN
4422 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
4423 Returns nonzero if a change was made. */
4426 bypass_block (bb, setcc, jump)
4434 insn = (setcc != NULL) ? setcc : jump;
4436 /* Determine set of register uses in INSN. */
4438 note_uses (&PATTERN (insn), find_used_regs, NULL);
4439 note = find_reg_equal_equiv_note (insn);
4441 find_used_regs (&XEXP (note, 0), NULL);
4444 for (e = bb->pred; e; e = enext)
4446 enext = e->pred_next;
4447 for (i = 0; i < reg_use_count; i++)
4449 struct reg_use *reg_used = ®_use_table[i];
4450 unsigned int regno = REGNO (reg_used->reg_rtx);
4451 basic_block dest, old_dest;
4455 if (regno >= max_gcse_regno)
4458 set = find_bypass_set (regno, e->src->index);
4463 src = SET_SRC (pc_set (jump));
4466 src = simplify_replace_rtx (src,
4467 SET_DEST (PATTERN (setcc)),
4468 SET_SRC (PATTERN (setcc)));
4470 new = simplify_replace_rtx (src, reg_used->reg_rtx,
4471 SET_SRC (set->expr));
4474 dest = FALLTHRU_EDGE (bb)->dest;
4475 else if (GET_CODE (new) == LABEL_REF)
4476 dest = BRANCH_EDGE (bb)->dest;
4480 /* Once basic block indices are stable, we should be able
4481 to use redirect_edge_and_branch_force instead. */
4483 if (dest != NULL && dest != old_dest
4484 && redirect_edge_and_branch (e, dest))
4486 /* Copy the register setter to the redirected edge.
4487 Don't copy CC0 setters, as CC0 is dead after jump. */
4490 rtx pat = PATTERN (setcc);
4491 if (!CC0_P (SET_DEST (pat)))
4492 insert_insn_on_edge (copy_insn (pat), e);
4495 if (gcse_file != NULL)
4497 fprintf (gcse_file, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
4498 regno, INSN_UID (jump));
4499 print_rtl (gcse_file, SET_SRC (set->expr));
4500 fprintf (gcse_file, "\nBypass edge from %d->%d to %d\n",
4501 e->src->index, old_dest->index, dest->index);
4511 /* Find basic blocks with more than one predecessor that only contain a
4512 single conditional jump. If the result of the comparison is known at
4513 compile-time from any incoming edge, redirect that edge to the
4514 appropriate target. Returns nonzero if a change was made. */
4517 bypass_conditional_jumps ()
4525 /* Note we start at block 1. */
4526 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
4530 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb,
4531 EXIT_BLOCK_PTR, next_bb)
4533 /* Check for more than one predecessor. */
4534 if (bb->pred && bb->pred->pred_next)
4537 for (insn = bb->head;
4538 insn != NULL && insn != NEXT_INSN (bb->end);
4539 insn = NEXT_INSN (insn))
4540 if (GET_CODE (insn) == INSN)
4544 if (GET_CODE (PATTERN (setcc)) != SET)
4547 dest = SET_DEST (PATTERN (setcc));
4548 if (REG_P (dest) || CC0_P (dest))
4553 else if (GET_CODE (insn) == JUMP_INSN)
4555 if (any_condjump_p (insn) && onlyjump_p (insn))
4556 changed |= bypass_block (bb, setcc, insn);
4559 else if (INSN_P (insn))
4564 /* If we bypassed any register setting insns, we inserted a
4565 copy on the redirected edge. These need to be commited. */
4567 commit_edge_insertions();
4572 /* Compute PRE+LCM working variables. */
4574 /* Local properties of expressions. */
4575 /* Nonzero for expressions that are transparent in the block. */
4576 static sbitmap *transp;
4578 /* Nonzero for expressions that are transparent at the end of the block.
4579 This is only zero for expressions killed by abnormal critical edge
4580 created by a calls. */
4581 static sbitmap *transpout;
4583 /* Nonzero for expressions that are computed (available) in the block. */
4584 static sbitmap *comp;
4586 /* Nonzero for expressions that are locally anticipatable in the block. */
4587 static sbitmap *antloc;
4589 /* Nonzero for expressions where this block is an optimal computation
4591 static sbitmap *pre_optimal;
4593 /* Nonzero for expressions which are redundant in a particular block. */
4594 static sbitmap *pre_redundant;
4596 /* Nonzero for expressions which should be inserted on a specific edge. */
4597 static sbitmap *pre_insert_map;
4599 /* Nonzero for expressions which should be deleted in a specific block. */
4600 static sbitmap *pre_delete_map;
4602 /* Contains the edge_list returned by pre_edge_lcm. */
4603 static struct edge_list *edge_list;
4605 /* Redundant insns. */
4606 static sbitmap pre_redundant_insns;
4608 /* Allocate vars used for PRE analysis. */
4611 alloc_pre_mem (n_blocks, n_exprs)
4612 int n_blocks, n_exprs;
4614 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
4615 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
4616 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
4619 pre_redundant = NULL;
4620 pre_insert_map = NULL;
4621 pre_delete_map = NULL;
4624 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
4626 /* pre_insert and pre_delete are allocated later. */
4629 /* Free vars used for PRE analysis. */
4634 sbitmap_vector_free (transp);
4635 sbitmap_vector_free (comp);
4637 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
4640 sbitmap_vector_free (pre_optimal);
4642 sbitmap_vector_free (pre_redundant);
4644 sbitmap_vector_free (pre_insert_map);
4646 sbitmap_vector_free (pre_delete_map);
4648 sbitmap_vector_free (ae_in);
4650 sbitmap_vector_free (ae_out);
4652 transp = comp = NULL;
4653 pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
4654 ae_in = ae_out = NULL;
4657 /* Top level routine to do the dataflow analysis needed by PRE. */
4662 sbitmap trapping_expr;
4666 compute_local_properties (transp, comp, antloc, 0);
4667 sbitmap_vector_zero (ae_kill, last_basic_block);
4669 /* Collect expressions which might trap. */
4670 trapping_expr = sbitmap_alloc (n_exprs);
4671 sbitmap_zero (trapping_expr);
4672 for (ui = 0; ui < expr_hash_table_size; ui++)
4675 for (e = expr_hash_table[ui]; e != NULL; e = e->next_same_hash)
4676 if (may_trap_p (e->expr))
4677 SET_BIT (trapping_expr, e->bitmap_index);
4680 /* Compute ae_kill for each basic block using:
4684 This is significantly faster than compute_ae_kill. */
4690 /* If the current block is the destination of an abnormal edge, we
4691 kill all trapping expressions because we won't be able to properly
4692 place the instruction on the edge. So make them neither
4693 anticipatable nor transparent. This is fairly conservative. */
4694 for (e = bb->pred; e ; e = e->pred_next)
4695 if (e->flags & EDGE_ABNORMAL)
4697 sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr);
4698 sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr);
4702 sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]);
4703 sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]);
4706 edge_list = pre_edge_lcm (gcse_file, n_exprs, transp, comp, antloc,
4707 ae_kill, &pre_insert_map, &pre_delete_map);
4708 sbitmap_vector_free (antloc);
4710 sbitmap_vector_free (ae_kill);
4712 sbitmap_free (trapping_expr);
4717 /* Return non-zero if an occurrence of expression EXPR in OCCR_BB would reach
4720 VISITED is a pointer to a working buffer for tracking which BB's have
4721 been visited. It is NULL for the top-level call.
4723 We treat reaching expressions that go through blocks containing the same
4724 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
4725 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
4726 2 as not reaching. The intent is to improve the probability of finding
4727 only one reaching expression and to reduce register lifetimes by picking
4728 the closest such expression. */
4731 pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited)
4732 basic_block occr_bb;
4739 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
4741 basic_block pred_bb = pred->src;
4743 if (pred->src == ENTRY_BLOCK_PTR
4744 /* Has predecessor has already been visited? */
4745 || visited[pred_bb->index])
4746 ;/* Nothing to do. */
4748 /* Does this predecessor generate this expression? */
4749 else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
4751 /* Is this the occurrence we're looking for?
4752 Note that there's only one generating occurrence per block
4753 so we just need to check the block number. */
4754 if (occr_bb == pred_bb)
4757 visited[pred_bb->index] = 1;
4759 /* Ignore this predecessor if it kills the expression. */
4760 else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
4761 visited[pred_bb->index] = 1;
4763 /* Neither gen nor kill. */
4766 visited[pred_bb->index] = 1;
4767 if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
4772 /* All paths have been checked. */
4776 /* The wrapper for pre_expr_reaches_here_work that ensures that any
4777 memory allocated for that function is returned. */
4780 pre_expr_reaches_here_p (occr_bb, expr, bb)
4781 basic_block occr_bb;
4786 char *visited = (char *) xcalloc (last_basic_block, 1);
4788 rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited);
4795 /* Given an expr, generate RTL which we can insert at the end of a BB,
4796 or on an edge. Set the block number of any insns generated to
4800 process_insert_insn (expr)
4803 rtx reg = expr->reaching_reg;
4804 rtx exp = copy_rtx (expr->expr);
4809 /* If the expression is something that's an operand, like a constant,
4810 just copy it to a register. */
4811 if (general_operand (exp, GET_MODE (reg)))
4812 emit_move_insn (reg, exp);
4814 /* Otherwise, make a new insn to compute this expression and make sure the
4815 insn will be recognized (this also adds any needed CLOBBERs). Copy the
4816 expression to make sure we don't have any sharing issues. */
4817 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode, reg, exp))))
4820 pat = gen_sequence ();
4826 /* Add EXPR to the end of basic block BB.
4828 This is used by both the PRE and code hoisting.
4830 For PRE, we want to verify that the expr is either transparent
4831 or locally anticipatable in the target block. This check makes
4832 no sense for code hoisting. */
4835 insert_insn_end_bb (expr, bb, pre)
4842 rtx reg = expr->reaching_reg;
4843 int regno = REGNO (reg);
4847 pat = process_insert_insn (expr);
4849 /* If the last insn is a jump, insert EXPR in front [taking care to
4850 handle cc0, etc. properly]. Similary we need to care trapping
4851 instructions in presence of non-call exceptions. */
4853 if (GET_CODE (insn) == JUMP_INSN
4854 || (GET_CODE (insn) == INSN
4855 && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL))))
4860 /* It should always be the case that we can put these instructions
4861 anywhere in the basic block with performing PRE optimizations.
4863 if (GET_CODE (insn) == INSN && pre
4864 && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
4865 && !TEST_BIT (transp[bb->index], expr->bitmap_index))
4868 /* If this is a jump table, then we can't insert stuff here. Since
4869 we know the previous real insn must be the tablejump, we insert
4870 the new instruction just before the tablejump. */
4871 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
4872 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
4873 insn = prev_real_insn (insn);
4876 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4877 if cc0 isn't set. */
4878 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
4880 insn = XEXP (note, 0);
4883 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
4884 if (maybe_cc0_setter
4885 && INSN_P (maybe_cc0_setter)
4886 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
4887 insn = maybe_cc0_setter;
4890 /* FIXME: What if something in cc0/jump uses value set in new insn? */
4891 new_insn = emit_insn_before (pat, insn);
4894 /* Likewise if the last insn is a call, as will happen in the presence
4895 of exception handling. */
4896 else if (GET_CODE (insn) == CALL_INSN
4897 && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL)))
4899 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
4900 we search backward and place the instructions before the first
4901 parameter is loaded. Do this for everyone for consistency and a
4902 presumtion that we'll get better code elsewhere as well.
4904 It should always be the case that we can put these instructions
4905 anywhere in the basic block with performing PRE optimizations.
4909 && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
4910 && !TEST_BIT (transp[bb->index], expr->bitmap_index))
4913 /* Since different machines initialize their parameter registers
4914 in different orders, assume nothing. Collect the set of all
4915 parameter registers. */
4916 insn = find_first_parameter_load (insn, bb->head);
4918 /* If we found all the parameter loads, then we want to insert
4919 before the first parameter load.
4921 If we did not find all the parameter loads, then we might have
4922 stopped on the head of the block, which could be a CODE_LABEL.
4923 If we inserted before the CODE_LABEL, then we would be putting
4924 the insn in the wrong basic block. In that case, put the insn
4925 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
4926 while (GET_CODE (insn) == CODE_LABEL
4927 || NOTE_INSN_BASIC_BLOCK_P (insn))
4928 insn = NEXT_INSN (insn);
4930 new_insn = emit_insn_before (pat, insn);
4933 new_insn = emit_insn_after (pat, insn);
4935 /* Keep block number table up to date.
4936 Note, PAT could be a multiple insn sequence, we have to make
4937 sure that each insn in the sequence is handled. */
4938 if (GET_CODE (pat) == SEQUENCE)
4940 for (i = 0; i < XVECLEN (pat, 0); i++)
4942 rtx insn = XVECEXP (pat, 0, i);
4944 add_label_notes (PATTERN (insn), new_insn);
4946 note_stores (PATTERN (insn), record_set_info, insn);
4951 add_label_notes (pat, new_insn);
4953 /* Keep register set table up to date. */
4954 record_one_set (regno, new_insn);
4957 gcse_create_count++;
4961 fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, ",
4962 bb->index, INSN_UID (new_insn));
4963 fprintf (gcse_file, "copying expression %d to reg %d\n",
4964 expr->bitmap_index, regno);
4968 /* Insert partially redundant expressions on edges in the CFG to make
4969 the expressions fully redundant. */
4972 pre_edge_insert (edge_list, index_map)
4973 struct edge_list *edge_list;
4974 struct expr **index_map;
4976 int e, i, j, num_edges, set_size, did_insert = 0;
4979 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
4980 if it reaches any of the deleted expressions. */
4982 set_size = pre_insert_map[0]->size;
4983 num_edges = NUM_EDGES (edge_list);
4984 inserted = sbitmap_vector_alloc (num_edges, n_exprs);
4985 sbitmap_vector_zero (inserted, num_edges);
4987 for (e = 0; e < num_edges; e++)
4990 basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
4992 for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
4994 SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
4996 for (j = indx; insert && j < n_exprs; j++, insert >>= 1)
4997 if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
4999 struct expr *expr = index_map[j];
5002 /* Now look at each deleted occurrence of this expression. */
5003 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5005 if (! occr->deleted_p)
5008 /* Insert this expression on this edge if if it would
5009 reach the deleted occurrence in BB. */
5010 if (!TEST_BIT (inserted[e], j))
5013 edge eg = INDEX_EDGE (edge_list, e);
5015 /* We can't insert anything on an abnormal and
5016 critical edge, so we insert the insn at the end of
5017 the previous block. There are several alternatives
5018 detailed in Morgans book P277 (sec 10.5) for
5019 handling this situation. This one is easiest for
5022 if ((eg->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
5023 insert_insn_end_bb (index_map[j], bb, 0);
5026 insn = process_insert_insn (index_map[j]);
5027 insert_insn_on_edge (insn, eg);
5032 fprintf (gcse_file, "PRE/HOIST: edge (%d,%d), ",
5034 INDEX_EDGE_SUCC_BB (edge_list, e)->index);
5035 fprintf (gcse_file, "copy expression %d\n",
5036 expr->bitmap_index);
5039 update_ld_motion_stores (expr);
5040 SET_BIT (inserted[e], j);
5042 gcse_create_count++;
5049 sbitmap_vector_free (inserted);
5053 /* Copy the result of INSN to REG. INDX is the expression number. */
5056 pre_insert_copy_insn (expr, insn)
5060 rtx reg = expr->reaching_reg;
5061 int regno = REGNO (reg);
5062 int indx = expr->bitmap_index;
5063 rtx set = single_set (insn);
5069 new_insn = emit_insn_after (gen_move_insn (reg, SET_DEST (set)), insn);
5071 /* Keep register set table up to date. */
5072 record_one_set (regno, new_insn);
5074 gcse_create_count++;
5078 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
5079 BLOCK_NUM (insn), INSN_UID (new_insn), indx,
5080 INSN_UID (insn), regno);
5081 update_ld_motion_stores (expr);
5084 /* Copy available expressions that reach the redundant expression
5085 to `reaching_reg'. */
5088 pre_insert_copies ()
5095 /* For each available expression in the table, copy the result to
5096 `reaching_reg' if the expression reaches a deleted one.
5098 ??? The current algorithm is rather brute force.
5099 Need to do some profiling. */
5101 for (i = 0; i < expr_hash_table_size; i++)
5102 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
5104 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
5105 we don't want to insert a copy here because the expression may not
5106 really be redundant. So only insert an insn if the expression was
5107 deleted. This test also avoids further processing if the
5108 expression wasn't deleted anywhere. */
5109 if (expr->reaching_reg == NULL)
5112 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5114 if (! occr->deleted_p)
5117 for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
5119 rtx insn = avail->insn;
5121 /* No need to handle this one if handled already. */
5122 if (avail->copied_p)
5125 /* Don't handle this one if it's a redundant one. */
5126 if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
5129 /* Or if the expression doesn't reach the deleted one. */
5130 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
5132 BLOCK_FOR_INSN (occr->insn)))
5135 /* Copy the result of avail to reaching_reg. */
5136 pre_insert_copy_insn (expr, insn);
5137 avail->copied_p = 1;
5143 /* Emit move from SRC to DEST noting the equivalence with expression computed
5146 gcse_emit_move_after (src, dest, insn)
5147 rtx src, dest, insn;
5150 rtx set = single_set (insn);
5154 /* This should never fail since we're creating a reg->reg copy
5155 we've verified to be valid. */
5157 new = emit_insn_after (gen_rtx_SET (VOIDmode, dest, src), insn);
5159 /* Note the equivalence for local CSE pass. */
5160 if ((note = find_reg_equal_equiv_note (insn)))
5161 eqv = XEXP (note, 0);
5163 eqv = SET_SRC (set);
5165 set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (src));
5170 /* Delete redundant computations.
5171 Deletion is done by changing the insn to copy the `reaching_reg' of
5172 the expression into the result of the SET. It is left to later passes
5173 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
5175 Returns non-zero if a change is made. */
5186 for (i = 0; i < expr_hash_table_size; i++)
5187 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
5189 int indx = expr->bitmap_index;
5191 /* We only need to search antic_occr since we require
5194 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5196 rtx insn = occr->insn;
5198 basic_block bb = BLOCK_FOR_INSN (insn);
5200 if (TEST_BIT (pre_delete_map[bb->index], indx))
5202 set = single_set (insn);
5206 /* Create a pseudo-reg to store the result of reaching
5207 expressions into. Get the mode for the new pseudo from
5208 the mode of the original destination pseudo. */
5209 if (expr->reaching_reg == NULL)
5211 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
5213 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
5215 occr->deleted_p = 1;
5216 SET_BIT (pre_redundant_insns, INSN_CUID (insn));
5223 "PRE: redundant insn %d (expression %d) in ",
5224 INSN_UID (insn), indx);
5225 fprintf (gcse_file, "bb %d, reaching reg is %d\n",
5226 bb->index, REGNO (expr->reaching_reg));
5235 /* Perform GCSE optimizations using PRE.
5236 This is called by one_pre_gcse_pass after all the dataflow analysis
5239 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
5240 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
5241 Compiler Design and Implementation.
5243 ??? A new pseudo reg is created to hold the reaching expression. The nice
5244 thing about the classical approach is that it would try to use an existing
5245 reg. If the register can't be adequately optimized [i.e. we introduce
5246 reload problems], one could add a pass here to propagate the new register
5249 ??? We don't handle single sets in PARALLELs because we're [currently] not
5250 able to copy the rest of the parallel when we insert copies to create full
5251 redundancies from partial redundancies. However, there's no reason why we
5252 can't handle PARALLELs in the cases where there are no partial
5259 int did_insert, changed;
5260 struct expr **index_map;
5263 /* Compute a mapping from expression number (`bitmap_index') to
5264 hash table entry. */
5266 index_map = (struct expr **) xcalloc (n_exprs, sizeof (struct expr *));
5267 for (i = 0; i < expr_hash_table_size; i++)
5268 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
5269 index_map[expr->bitmap_index] = expr;
5271 /* Reset bitmap used to track which insns are redundant. */
5272 pre_redundant_insns = sbitmap_alloc (max_cuid);
5273 sbitmap_zero (pre_redundant_insns);
5275 /* Delete the redundant insns first so that
5276 - we know what register to use for the new insns and for the other
5277 ones with reaching expressions
5278 - we know which insns are redundant when we go to create copies */
5280 changed = pre_delete ();
5282 did_insert = pre_edge_insert (edge_list, index_map);
5284 /* In other places with reaching expressions, copy the expression to the
5285 specially allocated pseudo-reg that reaches the redundant expr. */
5286 pre_insert_copies ();
5289 commit_edge_insertions ();
5294 sbitmap_free (pre_redundant_insns);
5298 /* Top level routine to perform one PRE GCSE pass.
5300 Return non-zero if a change was made. */
5303 one_pre_gcse_pass (pass)
5308 gcse_subst_count = 0;
5309 gcse_create_count = 0;
5311 alloc_expr_hash_table (max_cuid);
5312 add_noreturn_fake_exit_edges ();
5314 compute_ld_motion_mems ();
5316 compute_expr_hash_table ();
5317 trim_ld_motion_mems ();
5319 dump_hash_table (gcse_file, "Expression", expr_hash_table,
5320 expr_hash_table_size, n_exprs);
5324 alloc_pre_mem (last_basic_block, n_exprs);
5325 compute_pre_data ();
5326 changed |= pre_gcse ();
5327 free_edge_list (edge_list);
5332 remove_fake_edges ();
5333 free_expr_hash_table ();
5337 fprintf (gcse_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
5338 current_function_name, pass, bytes_used);
5339 fprintf (gcse_file, "%d substs, %d insns created\n",
5340 gcse_subst_count, gcse_create_count);
5346 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
5347 If notes are added to an insn which references a CODE_LABEL, the
5348 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
5349 because the following loop optimization pass requires them. */
5351 /* ??? This is very similar to the loop.c add_label_notes function. We
5352 could probably share code here. */
5354 /* ??? If there was a jump optimization pass after gcse and before loop,
5355 then we would not need to do this here, because jump would add the
5356 necessary REG_LABEL notes. */
5359 add_label_notes (x, insn)
5363 enum rtx_code code = GET_CODE (x);
5367 if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
5369 /* This code used to ignore labels that referred to dispatch tables to
5370 avoid flow generating (slighly) worse code.
5372 We no longer ignore such label references (see LABEL_REF handling in
5373 mark_jump_label for additional information). */
5375 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0),
5377 if (LABEL_P (XEXP (x, 0)))
5378 LABEL_NUSES (XEXP (x, 0))++;
5382 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
5385 add_label_notes (XEXP (x, i), insn);
5386 else if (fmt[i] == 'E')
5387 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5388 add_label_notes (XVECEXP (x, i, j), insn);
5392 /* Compute transparent outgoing information for each block.
5394 An expression is transparent to an edge unless it is killed by
5395 the edge itself. This can only happen with abnormal control flow,
5396 when the edge is traversed through a call. This happens with
5397 non-local labels and exceptions.
5399 This would not be necessary if we split the edge. While this is
5400 normally impossible for abnormal critical edges, with some effort
5401 it should be possible with exception handling, since we still have
5402 control over which handler should be invoked. But due to increased
5403 EH table sizes, this may not be worthwhile. */
5406 compute_transpout ()
5412 sbitmap_vector_ones (transpout, last_basic_block);
5416 /* Note that flow inserted a nop a the end of basic blocks that
5417 end in call instructions for reasons other than abnormal
5419 if (GET_CODE (bb->end) != CALL_INSN)
5422 for (i = 0; i < expr_hash_table_size; i++)
5423 for (expr = expr_hash_table[i]; expr ; expr = expr->next_same_hash)
5424 if (GET_CODE (expr->expr) == MEM)
5426 if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
5427 && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
5430 /* ??? Optimally, we would use interprocedural alias
5431 analysis to determine if this mem is actually killed
5433 RESET_BIT (transpout[bb->index], expr->bitmap_index);
5438 /* Removal of useless null pointer checks */
5440 /* Called via note_stores. X is set by SETTER. If X is a register we must
5441 invalidate nonnull_local and set nonnull_killed. DATA is really a
5442 `null_pointer_info *'.
5444 We ignore hard registers. */
5447 invalidate_nonnull_info (x, setter, data)
5449 rtx setter ATTRIBUTE_UNUSED;
5453 struct null_pointer_info *npi = (struct null_pointer_info *) data;
5455 while (GET_CODE (x) == SUBREG)
5458 /* Ignore anything that is not a register or is a hard register. */
5459 if (GET_CODE (x) != REG
5460 || REGNO (x) < npi->min_reg
5461 || REGNO (x) >= npi->max_reg)
5464 regno = REGNO (x) - npi->min_reg;
5466 RESET_BIT (npi->nonnull_local[npi->current_block->index], regno);
5467 SET_BIT (npi->nonnull_killed[npi->current_block->index], regno);
5470 /* Do null-pointer check elimination for the registers indicated in
5471 NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
5472 they are not our responsibility to free. */
5475 delete_null_pointer_checks_1 (block_reg, nonnull_avin,
5477 unsigned int *block_reg;
5478 sbitmap *nonnull_avin;
5479 sbitmap *nonnull_avout;
5480 struct null_pointer_info *npi;
5482 basic_block bb, current_block;
5483 sbitmap *nonnull_local = npi->nonnull_local;
5484 sbitmap *nonnull_killed = npi->nonnull_killed;
5486 /* Compute local properties, nonnull and killed. A register will have
5487 the nonnull property if at the end of the current block its value is
5488 known to be nonnull. The killed property indicates that somewhere in
5489 the block any information we had about the register is killed.
5491 Note that a register can have both properties in a single block. That
5492 indicates that it's killed, then later in the block a new value is
5494 sbitmap_vector_zero (nonnull_local, last_basic_block);
5495 sbitmap_vector_zero (nonnull_killed, last_basic_block);
5497 FOR_EACH_BB (current_block)
5499 rtx insn, stop_insn;
5501 /* Set the current block for invalidate_nonnull_info. */
5502 npi->current_block = current_block;
5504 /* Scan each insn in the basic block looking for memory references and
5506 stop_insn = NEXT_INSN (current_block->end);
5507 for (insn = current_block->head;
5509 insn = NEXT_INSN (insn))
5514 /* Ignore anything that is not a normal insn. */
5515 if (! INSN_P (insn))
5518 /* Basically ignore anything that is not a simple SET. We do have
5519 to make sure to invalidate nonnull_local and set nonnull_killed
5520 for such insns though. */
5521 set = single_set (insn);
5524 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5528 /* See if we've got a usable memory load. We handle it first
5529 in case it uses its address register as a dest (which kills
5530 the nonnull property). */
5531 if (GET_CODE (SET_SRC (set)) == MEM
5532 && GET_CODE ((reg = XEXP (SET_SRC (set), 0))) == REG
5533 && REGNO (reg) >= npi->min_reg
5534 && REGNO (reg) < npi->max_reg)
5535 SET_BIT (nonnull_local[current_block->index],
5536 REGNO (reg) - npi->min_reg);
5538 /* Now invalidate stuff clobbered by this insn. */
5539 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5541 /* And handle stores, we do these last since any sets in INSN can
5542 not kill the nonnull property if it is derived from a MEM
5543 appearing in a SET_DEST. */
5544 if (GET_CODE (SET_DEST (set)) == MEM
5545 && GET_CODE ((reg = XEXP (SET_DEST (set), 0))) == REG
5546 && REGNO (reg) >= npi->min_reg
5547 && REGNO (reg) < npi->max_reg)
5548 SET_BIT (nonnull_local[current_block->index],
5549 REGNO (reg) - npi->min_reg);
5553 /* Now compute global properties based on the local properties. This
5554 is a classic global availablity algorithm. */
5555 compute_available (nonnull_local, nonnull_killed,
5556 nonnull_avout, nonnull_avin);
5558 /* Now look at each bb and see if it ends with a compare of a value
5562 rtx last_insn = bb->end;
5563 rtx condition, earliest;
5564 int compare_and_branch;
5566 /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
5567 since BLOCK_REG[BB] is zero if this block did not end with a
5568 comparison against zero, this condition works. */
5569 if (block_reg[bb->index] < npi->min_reg
5570 || block_reg[bb->index] >= npi->max_reg)
5573 /* LAST_INSN is a conditional jump. Get its condition. */
5574 condition = get_condition (last_insn, &earliest);
5576 /* If we can't determine the condition then skip. */
5580 /* Is the register known to have a nonzero value? */
5581 if (!TEST_BIT (nonnull_avout[bb->index], block_reg[bb->index] - npi->min_reg))
5584 /* Try to compute whether the compare/branch at the loop end is one or
5585 two instructions. */
5586 if (earliest == last_insn)
5587 compare_and_branch = 1;
5588 else if (earliest == prev_nonnote_insn (last_insn))
5589 compare_and_branch = 2;
5593 /* We know the register in this comparison is nonnull at exit from
5594 this block. We can optimize this comparison. */
5595 if (GET_CODE (condition) == NE)
5599 new_jump = emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn)),
5601 JUMP_LABEL (new_jump) = JUMP_LABEL (last_insn);
5602 LABEL_NUSES (JUMP_LABEL (new_jump))++;
5603 emit_barrier_after (new_jump);
5606 delete_insn (last_insn);
5607 if (compare_and_branch == 2)
5608 delete_insn (earliest);
5609 purge_dead_edges (bb);
5611 /* Don't check this block again. (Note that BLOCK_END is
5612 invalid here; we deleted the last instruction in the
5614 block_reg[bb->index] = 0;
5618 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
5621 This is conceptually similar to global constant/copy propagation and
5622 classic global CSE (it even uses the same dataflow equations as cprop).
5624 If a register is used as memory address with the form (mem (reg)), then we
5625 know that REG can not be zero at that point in the program. Any instruction
5626 which sets REG "kills" this property.
5628 So, if every path leading to a conditional branch has an available memory
5629 reference of that form, then we know the register can not have the value
5630 zero at the conditional branch.
5632 So we merely need to compute the local properies and propagate that data
5633 around the cfg, then optimize where possible.
5635 We run this pass two times. Once before CSE, then again after CSE. This
5636 has proven to be the most profitable approach. It is rare for new
5637 optimization opportunities of this nature to appear after the first CSE
5640 This could probably be integrated with global cprop with a little work. */
5643 delete_null_pointer_checks (f)
5644 rtx f ATTRIBUTE_UNUSED;
5646 sbitmap *nonnull_avin, *nonnull_avout;
5647 unsigned int *block_reg;
5652 struct null_pointer_info npi;
5654 /* If we have only a single block, then there's nothing to do. */
5655 if (n_basic_blocks <= 1)
5658 /* Trying to perform global optimizations on flow graphs which have
5659 a high connectivity will take a long time and is unlikely to be
5660 particularly useful.
5662 In normal circumstances a cfg should have about twice as many edges
5663 as blocks. But we do not want to punish small functions which have
5664 a couple switch statements. So we require a relatively large number
5665 of basic blocks and the ratio of edges to blocks to be high. */
5666 if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
5669 /* We need four bitmaps, each with a bit for each register in each
5671 max_reg = max_reg_num ();
5672 regs_per_pass = get_bitmap_width (4, last_basic_block, max_reg);
5674 /* Allocate bitmaps to hold local and global properties. */
5675 npi.nonnull_local = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5676 npi.nonnull_killed = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5677 nonnull_avin = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5678 nonnull_avout = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5680 /* Go through the basic blocks, seeing whether or not each block
5681 ends with a conditional branch whose condition is a comparison
5682 against zero. Record the register compared in BLOCK_REG. */
5683 block_reg = (unsigned int *) xcalloc (last_basic_block, sizeof (int));
5686 rtx last_insn = bb->end;
5687 rtx condition, earliest, reg;
5689 /* We only want conditional branches. */
5690 if (GET_CODE (last_insn) != JUMP_INSN
5691 || !any_condjump_p (last_insn)
5692 || !onlyjump_p (last_insn))
5695 /* LAST_INSN is a conditional jump. Get its condition. */
5696 condition = get_condition (last_insn, &earliest);
5698 /* If we were unable to get the condition, or it is not an equality
5699 comparison against zero then there's nothing we can do. */
5701 || (GET_CODE (condition) != NE && GET_CODE (condition) != EQ)
5702 || GET_CODE (XEXP (condition, 1)) != CONST_INT
5703 || (XEXP (condition, 1)
5704 != CONST0_RTX (GET_MODE (XEXP (condition, 0)))))
5707 /* We must be checking a register against zero. */
5708 reg = XEXP (condition, 0);
5709 if (GET_CODE (reg) != REG)
5712 block_reg[bb->index] = REGNO (reg);
5715 /* Go through the algorithm for each block of registers. */
5716 for (reg = FIRST_PSEUDO_REGISTER; reg < max_reg; reg += regs_per_pass)
5719 npi.max_reg = MIN (reg + regs_per_pass, max_reg);
5720 delete_null_pointer_checks_1 (block_reg, nonnull_avin,
5721 nonnull_avout, &npi);
5724 /* Free the table of registers compared at the end of every block. */
5728 sbitmap_vector_free (npi.nonnull_local);
5729 sbitmap_vector_free (npi.nonnull_killed);
5730 sbitmap_vector_free (nonnull_avin);
5731 sbitmap_vector_free (nonnull_avout);
5734 /* Code Hoisting variables and subroutines. */
5736 /* Very busy expressions. */
5737 static sbitmap *hoist_vbein;
5738 static sbitmap *hoist_vbeout;
5740 /* Hoistable expressions. */
5741 static sbitmap *hoist_exprs;
5743 /* Dominator bitmaps. */
5744 static sbitmap *dominators;
5746 /* ??? We could compute post dominators and run this algorithm in
5747 reverse to to perform tail merging, doing so would probably be
5748 more effective than the tail merging code in jump.c.
5750 It's unclear if tail merging could be run in parallel with
5751 code hoisting. It would be nice. */
5753 /* Allocate vars used for code hoisting analysis. */
5756 alloc_code_hoist_mem (n_blocks, n_exprs)
5757 int n_blocks, n_exprs;
5759 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
5760 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
5761 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
5763 hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
5764 hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
5765 hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
5766 transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
5768 dominators = sbitmap_vector_alloc (n_blocks, n_blocks);
5771 /* Free vars used for code hoisting analysis. */
5774 free_code_hoist_mem ()
5776 sbitmap_vector_free (antloc);
5777 sbitmap_vector_free (transp);
5778 sbitmap_vector_free (comp);
5780 sbitmap_vector_free (hoist_vbein);
5781 sbitmap_vector_free (hoist_vbeout);
5782 sbitmap_vector_free (hoist_exprs);
5783 sbitmap_vector_free (transpout);
5785 sbitmap_vector_free (dominators);
5788 /* Compute the very busy expressions at entry/exit from each block.
5790 An expression is very busy if all paths from a given point
5791 compute the expression. */
5794 compute_code_hoist_vbeinout ()
5796 int changed, passes;
5799 sbitmap_vector_zero (hoist_vbeout, last_basic_block);
5800 sbitmap_vector_zero (hoist_vbein, last_basic_block);
5809 /* We scan the blocks in the reverse order to speed up
5811 FOR_EACH_BB_REVERSE (bb)
5813 changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index], antloc[bb->index],
5814 hoist_vbeout[bb->index], transp[bb->index]);
5815 if (bb->next_bb != EXIT_BLOCK_PTR)
5816 sbitmap_intersection_of_succs (hoist_vbeout[bb->index], hoist_vbein, bb->index);
5823 fprintf (gcse_file, "hoisting vbeinout computation: %d passes\n", passes);
5826 /* Top level routine to do the dataflow analysis needed by code hoisting. */
5829 compute_code_hoist_data ()
5831 compute_local_properties (transp, comp, antloc, 0);
5832 compute_transpout ();
5833 compute_code_hoist_vbeinout ();
5834 calculate_dominance_info (NULL, dominators, CDI_DOMINATORS);
5836 fprintf (gcse_file, "\n");
5839 /* Determine if the expression identified by EXPR_INDEX would
5840 reach BB unimpared if it was placed at the end of EXPR_BB.
5842 It's unclear exactly what Muchnick meant by "unimpared". It seems
5843 to me that the expression must either be computed or transparent in
5844 *every* block in the path(s) from EXPR_BB to BB. Any other definition
5845 would allow the expression to be hoisted out of loops, even if
5846 the expression wasn't a loop invariant.
5848 Contrast this to reachability for PRE where an expression is
5849 considered reachable if *any* path reaches instead of *all*
5853 hoist_expr_reaches_here_p (expr_bb, expr_index, bb, visited)
5854 basic_block expr_bb;
5860 int visited_allocated_locally = 0;
5863 if (visited == NULL)
5865 visited_allocated_locally = 1;
5866 visited = xcalloc (last_basic_block, 1);
5869 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
5871 basic_block pred_bb = pred->src;
5873 if (pred->src == ENTRY_BLOCK_PTR)
5875 else if (visited[pred_bb->index])
5878 /* Does this predecessor generate this expression? */
5879 else if (TEST_BIT (comp[pred_bb->index], expr_index))
5881 else if (! TEST_BIT (transp[pred_bb->index], expr_index))
5887 visited[pred_bb->index] = 1;
5888 if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
5893 if (visited_allocated_locally)
5896 return (pred == NULL);
5899 /* Actually perform code hoisting. */
5904 basic_block bb, dominated;
5906 struct expr **index_map;
5909 sbitmap_vector_zero (hoist_exprs, last_basic_block);
5911 /* Compute a mapping from expression number (`bitmap_index') to
5912 hash table entry. */
5914 index_map = (struct expr **) xcalloc (n_exprs, sizeof (struct expr *));
5915 for (i = 0; i < expr_hash_table_size; i++)
5916 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
5917 index_map[expr->bitmap_index] = expr;
5919 /* Walk over each basic block looking for potentially hoistable
5920 expressions, nothing gets hoisted from the entry block. */
5924 int insn_inserted_p;
5926 /* Examine each expression that is very busy at the exit of this
5927 block. These are the potentially hoistable expressions. */
5928 for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++)
5932 if (TEST_BIT (hoist_vbeout[bb->index], i) && TEST_BIT (transpout[bb->index], i))
5934 /* We've found a potentially hoistable expression, now
5935 we look at every block BB dominates to see if it
5936 computes the expression. */
5937 FOR_EACH_BB (dominated)
5939 /* Ignore self dominance. */
5941 || ! TEST_BIT (dominators[dominated->index], bb->index))
5944 /* We've found a dominated block, now see if it computes
5945 the busy expression and whether or not moving that
5946 expression to the "beginning" of that block is safe. */
5947 if (!TEST_BIT (antloc[dominated->index], i))
5950 /* Note if the expression would reach the dominated block
5951 unimpared if it was placed at the end of BB.
5953 Keep track of how many times this expression is hoistable
5954 from a dominated block into BB. */
5955 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
5959 /* If we found more than one hoistable occurrence of this
5960 expression, then note it in the bitmap of expressions to
5961 hoist. It makes no sense to hoist things which are computed
5962 in only one BB, and doing so tends to pessimize register
5963 allocation. One could increase this value to try harder
5964 to avoid any possible code expansion due to register
5965 allocation issues; however experiments have shown that
5966 the vast majority of hoistable expressions are only movable
5967 from two successors, so raising this threshhold is likely
5968 to nullify any benefit we get from code hoisting. */
5971 SET_BIT (hoist_exprs[bb->index], i);
5977 /* If we found nothing to hoist, then quit now. */
5981 /* Loop over all the hoistable expressions. */
5982 for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++)
5984 /* We want to insert the expression into BB only once, so
5985 note when we've inserted it. */
5986 insn_inserted_p = 0;
5988 /* These tests should be the same as the tests above. */
5989 if (TEST_BIT (hoist_vbeout[bb->index], i))
5991 /* We've found a potentially hoistable expression, now
5992 we look at every block BB dominates to see if it
5993 computes the expression. */
5994 FOR_EACH_BB (dominated)
5996 /* Ignore self dominance. */
5998 || ! TEST_BIT (dominators[dominated->index], bb->index))
6001 /* We've found a dominated block, now see if it computes
6002 the busy expression and whether or not moving that
6003 expression to the "beginning" of that block is safe. */
6004 if (!TEST_BIT (antloc[dominated->index], i))
6007 /* The expression is computed in the dominated block and
6008 it would be safe to compute it at the start of the
6009 dominated block. Now we have to determine if the
6010 expression would reach the dominated block if it was
6011 placed at the end of BB. */
6012 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
6014 struct expr *expr = index_map[i];
6015 struct occr *occr = expr->antic_occr;
6019 /* Find the right occurrence of this expression. */
6020 while (BLOCK_FOR_INSN (occr->insn) != dominated && occr)
6023 /* Should never happen. */
6029 set = single_set (insn);
6033 /* Create a pseudo-reg to store the result of reaching
6034 expressions into. Get the mode for the new pseudo
6035 from the mode of the original destination pseudo. */
6036 if (expr->reaching_reg == NULL)
6038 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
6040 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
6042 occr->deleted_p = 1;
6043 if (!insn_inserted_p)
6045 insert_insn_end_bb (index_map[i], bb, 0);
6046 insn_inserted_p = 1;
6057 /* Top level routine to perform one code hoisting (aka unification) pass
6059 Return non-zero if a change was made. */
6062 one_code_hoisting_pass ()
6066 alloc_expr_hash_table (max_cuid);
6067 compute_expr_hash_table ();
6069 dump_hash_table (gcse_file, "Code Hosting Expressions", expr_hash_table,
6070 expr_hash_table_size, n_exprs);
6074 alloc_code_hoist_mem (last_basic_block, n_exprs);
6075 compute_code_hoist_data ();
6077 free_code_hoist_mem ();
6080 free_expr_hash_table ();
6085 /* Here we provide the things required to do store motion towards
6086 the exit. In order for this to be effective, gcse also needed to
6087 be taught how to move a load when it is kill only by a store to itself.
6092 void foo(float scale)
6094 for (i=0; i<10; i++)
6098 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
6099 the load out since its live around the loop, and stored at the bottom
6102 The 'Load Motion' referred to and implemented in this file is
6103 an enhancement to gcse which when using edge based lcm, recognizes
6104 this situation and allows gcse to move the load out of the loop.
6106 Once gcse has hoisted the load, store motion can then push this
6107 load towards the exit, and we end up with no loads or stores of 'i'
6110 /* This will search the ldst list for a matching expression. If it
6111 doesn't find one, we create one and initialize it. */
6113 static struct ls_expr *
6117 struct ls_expr * ptr;
6119 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
6120 if (expr_equiv_p (ptr->pattern, x))
6125 ptr = (struct ls_expr *) xmalloc (sizeof (struct ls_expr));
6127 ptr->next = pre_ldst_mems;
6130 ptr->loads = NULL_RTX;
6131 ptr->stores = NULL_RTX;
6132 ptr->reaching_reg = NULL_RTX;
6135 ptr->hash_index = 0;
6136 pre_ldst_mems = ptr;
6142 /* Free up an individual ldst entry. */
6145 free_ldst_entry (ptr)
6146 struct ls_expr * ptr;
6148 free_INSN_LIST_list (& ptr->loads);
6149 free_INSN_LIST_list (& ptr->stores);
6154 /* Free up all memory associated with the ldst list. */
6159 while (pre_ldst_mems)
6161 struct ls_expr * tmp = pre_ldst_mems;
6163 pre_ldst_mems = pre_ldst_mems->next;
6165 free_ldst_entry (tmp);
6168 pre_ldst_mems = NULL;
6171 /* Dump debugging info about the ldst list. */
6174 print_ldst_list (file)
6177 struct ls_expr * ptr;
6179 fprintf (file, "LDST list: \n");
6181 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
6183 fprintf (file, " Pattern (%3d): ", ptr->index);
6185 print_rtl (file, ptr->pattern);
6187 fprintf (file, "\n Loads : ");
6190 print_rtl (file, ptr->loads);
6192 fprintf (file, "(nil)");
6194 fprintf (file, "\n Stores : ");
6197 print_rtl (file, ptr->stores);
6199 fprintf (file, "(nil)");
6201 fprintf (file, "\n\n");
6204 fprintf (file, "\n");
6207 /* Returns 1 if X is in the list of ldst only expressions. */
6209 static struct ls_expr *
6210 find_rtx_in_ldst (x)
6213 struct ls_expr * ptr;
6215 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6216 if (expr_equiv_p (ptr->pattern, x) && ! ptr->invalid)
6222 /* Assign each element of the list of mems a monotonically increasing value. */
6227 struct ls_expr * ptr;
6230 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6236 /* Return first item in the list. */
6238 static inline struct ls_expr *
6241 return pre_ldst_mems;
6244 /* Return the next item in ther list after the specified one. */
6246 static inline struct ls_expr *
6248 struct ls_expr * ptr;
6253 /* Load Motion for loads which only kill themselves. */
6255 /* Return true if x is a simple MEM operation, with no registers or
6256 side effects. These are the types of loads we consider for the
6257 ld_motion list, otherwise we let the usual aliasing take care of it. */
6263 if (GET_CODE (x) != MEM)
6266 if (MEM_VOLATILE_P (x))
6269 if (GET_MODE (x) == BLKmode)
6272 if (!rtx_varies_p (XEXP (x, 0), 0))
6278 /* Make sure there isn't a buried reference in this pattern anywhere.
6279 If there is, invalidate the entry for it since we're not capable
6280 of fixing it up just yet.. We have to be sure we know about ALL
6281 loads since the aliasing code will allow all entries in the
6282 ld_motion list to not-alias itself. If we miss a load, we will get
6283 the wrong value since gcse might common it and we won't know to
6287 invalidate_any_buried_refs (x)
6292 struct ls_expr * ptr;
6294 /* Invalidate it in the list. */
6295 if (GET_CODE (x) == MEM && simple_mem (x))
6297 ptr = ldst_entry (x);
6301 /* Recursively process the insn. */
6302 fmt = GET_RTX_FORMAT (GET_CODE (x));
6304 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
6307 invalidate_any_buried_refs (XEXP (x, i));
6308 else if (fmt[i] == 'E')
6309 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6310 invalidate_any_buried_refs (XVECEXP (x, i, j));
6314 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
6315 being defined as MEM loads and stores to symbols, with no
6316 side effects and no registers in the expression. If there are any
6317 uses/defs which don't match this criteria, it is invalidated and
6318 trimmed out later. */
6321 compute_ld_motion_mems ()
6323 struct ls_expr * ptr;
6327 pre_ldst_mems = NULL;
6331 for (insn = bb->head;
6332 insn && insn != NEXT_INSN (bb->end);
6333 insn = NEXT_INSN (insn))
6335 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
6337 if (GET_CODE (PATTERN (insn)) == SET)
6339 rtx src = SET_SRC (PATTERN (insn));
6340 rtx dest = SET_DEST (PATTERN (insn));
6342 /* Check for a simple LOAD... */
6343 if (GET_CODE (src) == MEM && simple_mem (src))
6345 ptr = ldst_entry (src);
6346 if (GET_CODE (dest) == REG)
6347 ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
6353 /* Make sure there isn't a buried load somewhere. */
6354 invalidate_any_buried_refs (src);
6357 /* Check for stores. Don't worry about aliased ones, they
6358 will block any movement we might do later. We only care
6359 about this exact pattern since those are the only
6360 circumstance that we will ignore the aliasing info. */
6361 if (GET_CODE (dest) == MEM && simple_mem (dest))
6363 ptr = ldst_entry (dest);
6365 if (GET_CODE (src) != MEM
6366 && GET_CODE (src) != ASM_OPERANDS)
6367 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
6373 invalidate_any_buried_refs (PATTERN (insn));
6379 /* Remove any references that have been either invalidated or are not in the
6380 expression list for pre gcse. */
6383 trim_ld_motion_mems ()
6385 struct ls_expr * last = NULL;
6386 struct ls_expr * ptr = first_ls_expr ();
6390 int del = ptr->invalid;
6391 struct expr * expr = NULL;
6393 /* Delete if entry has been made invalid. */
6399 /* Delete if we cannot find this mem in the expression list. */
6400 for (i = 0; i < expr_hash_table_size && del; i++)
6402 for (expr = expr_hash_table[i];
6404 expr = expr->next_same_hash)
6405 if (expr_equiv_p (expr->expr, ptr->pattern))
6417 last->next = ptr->next;
6418 free_ldst_entry (ptr);
6423 pre_ldst_mems = pre_ldst_mems->next;
6424 free_ldst_entry (ptr);
6425 ptr = pre_ldst_mems;
6430 /* Set the expression field if we are keeping it. */
6437 /* Show the world what we've found. */
6438 if (gcse_file && pre_ldst_mems != NULL)
6439 print_ldst_list (gcse_file);
6442 /* This routine will take an expression which we are replacing with
6443 a reaching register, and update any stores that are needed if
6444 that expression is in the ld_motion list. Stores are updated by
6445 copying their SRC to the reaching register, and then storeing
6446 the reaching register into the store location. These keeps the
6447 correct value in the reaching register for the loads. */
6450 update_ld_motion_stores (expr)
6453 struct ls_expr * mem_ptr;
6455 if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
6457 /* We can try to find just the REACHED stores, but is shouldn't
6458 matter to set the reaching reg everywhere... some might be
6459 dead and should be eliminated later. */
6461 /* We replace SET mem = expr with
6463 SET mem = reg , where reg is the
6464 reaching reg used in the load. */
6465 rtx list = mem_ptr->stores;
6467 for ( ; list != NULL_RTX; list = XEXP (list, 1))
6469 rtx insn = XEXP (list, 0);
6470 rtx pat = PATTERN (insn);
6471 rtx src = SET_SRC (pat);
6472 rtx reg = expr->reaching_reg;
6475 /* If we've already copied it, continue. */
6476 if (expr->reaching_reg == src)
6481 fprintf (gcse_file, "PRE: store updated with reaching reg ");
6482 print_rtl (gcse_file, expr->reaching_reg);
6483 fprintf (gcse_file, ":\n ");
6484 print_inline_rtx (gcse_file, insn, 8);
6485 fprintf (gcse_file, "\n");
6488 copy = gen_move_insn ( reg, SET_SRC (pat));
6489 new = emit_insn_before (copy, insn);
6490 record_one_set (REGNO (reg), new);
6491 SET_SRC (pat) = reg;
6493 /* un-recognize this pattern since it's probably different now. */
6494 INSN_CODE (insn) = -1;
6495 gcse_create_count++;
6500 /* Store motion code. */
6502 /* This is used to communicate the target bitvector we want to use in the
6503 reg_set_info routine when called via the note_stores mechanism. */
6504 static sbitmap * regvec;
6506 /* Used in computing the reverse edge graph bit vectors. */
6507 static sbitmap * st_antloc;
6509 /* Global holding the number of store expressions we are dealing with. */
6510 static int num_stores;
6512 /* Checks to set if we need to mark a register set. Called from note_stores. */
6515 reg_set_info (dest, setter, data)
6516 rtx dest, setter ATTRIBUTE_UNUSED;
6517 void * data ATTRIBUTE_UNUSED;
6519 if (GET_CODE (dest) == SUBREG)
6520 dest = SUBREG_REG (dest);
6522 if (GET_CODE (dest) == REG)
6523 SET_BIT (*regvec, REGNO (dest));
6526 /* Return non-zero if the register operands of expression X are killed
6527 anywhere in basic block BB. */
6530 store_ops_ok (x, bb)
6538 /* Repeat is used to turn tail-recursion into iteration. */
6544 code = GET_CODE (x);
6548 /* If a reg has changed after us in this
6549 block, the operand has been killed. */
6550 return TEST_BIT (reg_set_in_block[bb->index], REGNO (x));
6578 i = GET_RTX_LENGTH (code) - 1;
6579 fmt = GET_RTX_FORMAT (code);
6585 rtx tem = XEXP (x, i);
6587 /* If we are about to do the last recursive call
6588 needed at this level, change it into iteration.
6589 This function is called enough to be worth it. */
6596 if (! store_ops_ok (tem, bb))
6599 else if (fmt[i] == 'E')
6603 for (j = 0; j < XVECLEN (x, i); j++)
6605 if (! store_ops_ok (XVECEXP (x, i, j), bb))
6614 /* Determine whether insn is MEM store pattern that we will consider moving. */
6617 find_moveable_store (insn)
6620 struct ls_expr * ptr;
6621 rtx dest = PATTERN (insn);
6623 if (GET_CODE (dest) != SET
6624 || GET_CODE (SET_SRC (dest)) == ASM_OPERANDS)
6627 dest = SET_DEST (dest);
6629 if (GET_CODE (dest) != MEM || MEM_VOLATILE_P (dest)
6630 || GET_MODE (dest) == BLKmode)
6633 if (GET_CODE (XEXP (dest, 0)) != SYMBOL_REF)
6636 if (rtx_varies_p (XEXP (dest, 0), 0))
6639 ptr = ldst_entry (dest);
6640 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
6643 /* Perform store motion. Much like gcse, except we move expressions the
6644 other way by looking at the flowgraph in reverse. */
6647 compute_store_table ()
6654 max_gcse_regno = max_reg_num ();
6656 reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (last_basic_block,
6658 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
6661 /* Find all the stores we care about. */
6664 regvec = & (reg_set_in_block[bb->index]);
6665 for (insn = bb->end;
6666 insn && insn != PREV_INSN (bb->end);
6667 insn = PREV_INSN (insn))
6669 /* Ignore anything that is not a normal insn. */
6670 if (! INSN_P (insn))
6673 if (GET_CODE (insn) == CALL_INSN)
6675 bool clobbers_all = false;
6676 #ifdef NON_SAVING_SETJMP
6677 if (NON_SAVING_SETJMP
6678 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
6679 clobbers_all = true;
6682 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
6684 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
6685 SET_BIT (reg_set_in_block[bb->index], regno);
6688 pat = PATTERN (insn);
6689 note_stores (pat, reg_set_info, NULL);
6691 /* Now that we've marked regs, look for stores. */
6692 if (GET_CODE (pat) == SET)
6693 find_moveable_store (insn);
6697 ret = enumerate_ldsts ();
6701 fprintf (gcse_file, "Store Motion Expressions.\n");
6702 print_ldst_list (gcse_file);
6708 /* Check to see if the load X is aliased with STORE_PATTERN. */
6711 load_kills_store (x, store_pattern)
6712 rtx x, store_pattern;
6714 if (true_dependence (x, GET_MODE (x), store_pattern, rtx_addr_varies_p))
6719 /* Go through the entire insn X, looking for any loads which might alias
6720 STORE_PATTERN. Return 1 if found. */
6723 find_loads (x, store_pattern)
6724 rtx x, store_pattern;
6733 if (GET_CODE (x) == SET)
6736 if (GET_CODE (x) == MEM)
6738 if (load_kills_store (x, store_pattern))
6742 /* Recursively process the insn. */
6743 fmt = GET_RTX_FORMAT (GET_CODE (x));
6745 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
6748 ret |= find_loads (XEXP (x, i), store_pattern);
6749 else if (fmt[i] == 'E')
6750 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6751 ret |= find_loads (XVECEXP (x, i, j), store_pattern);
6756 /* Check if INSN kills the store pattern X (is aliased with it).
6757 Return 1 if it it does. */
6760 store_killed_in_insn (x, insn)
6763 if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
6766 if (GET_CODE (insn) == CALL_INSN)
6768 /* A normal or pure call might read from pattern,
6769 but a const call will not. */
6770 return ! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn);
6773 if (GET_CODE (PATTERN (insn)) == SET)
6775 rtx pat = PATTERN (insn);
6776 /* Check for memory stores to aliased objects. */
6777 if (GET_CODE (SET_DEST (pat)) == MEM && !expr_equiv_p (SET_DEST (pat), x))
6778 /* pretend its a load and check for aliasing. */
6779 if (find_loads (SET_DEST (pat), x))
6781 return find_loads (SET_SRC (pat), x);
6784 return find_loads (PATTERN (insn), x);
6787 /* Returns 1 if the expression X is loaded or clobbered on or after INSN
6788 within basic block BB. */
6791 store_killed_after (x, insn, bb)
6800 /* Check if the register operands of the store are OK in this block.
6801 Note that if registers are changed ANYWHERE in the block, we'll
6802 decide we can't move it, regardless of whether it changed above
6803 or below the store. This could be improved by checking the register
6804 operands while lookinng for aliasing in each insn. */
6805 if (!store_ops_ok (XEXP (x, 0), bb))
6808 for ( ; insn && insn != NEXT_INSN (last); insn = NEXT_INSN (insn))
6809 if (store_killed_in_insn (x, insn))
6815 /* Returns 1 if the expression X is loaded or clobbered on or before INSN
6816 within basic block BB. */
6818 store_killed_before (x, insn, bb)
6822 rtx first = bb->head;
6825 return store_killed_in_insn (x, insn);
6827 /* Check if the register operands of the store are OK in this block.
6828 Note that if registers are changed ANYWHERE in the block, we'll
6829 decide we can't move it, regardless of whether it changed above
6830 or below the store. This could be improved by checking the register
6831 operands while lookinng for aliasing in each insn. */
6832 if (!store_ops_ok (XEXP (x, 0), bb))
6835 for ( ; insn && insn != PREV_INSN (first); insn = PREV_INSN (insn))
6836 if (store_killed_in_insn (x, insn))
6842 #define ANTIC_STORE_LIST(x) ((x)->loads)
6843 #define AVAIL_STORE_LIST(x) ((x)->stores)
6845 /* Given the table of available store insns at the end of blocks,
6846 determine which ones are not killed by aliasing, and generate
6847 the appropriate vectors for gen and killed. */
6849 build_store_vectors ()
6853 struct ls_expr * ptr;
6855 /* Build the gen_vector. This is any store in the table which is not killed
6856 by aliasing later in its block. */
6857 ae_gen = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
6858 sbitmap_vector_zero (ae_gen, last_basic_block);
6860 st_antloc = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
6861 sbitmap_vector_zero (st_antloc, last_basic_block);
6863 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6865 /* Put all the stores into either the antic list, or the avail list,
6867 rtx store_list = ptr->stores;
6868 ptr->stores = NULL_RTX;
6870 for (st = store_list; st != NULL; st = XEXP (st, 1))
6872 insn = XEXP (st, 0);
6873 bb = BLOCK_FOR_INSN (insn);
6875 if (!store_killed_after (ptr->pattern, insn, bb))
6877 /* If we've already seen an availale expression in this block,
6878 we can delete the one we saw already (It occurs earlier in
6879 the block), and replace it with this one). We'll copy the
6880 old SRC expression to an unused register in case there
6881 are any side effects. */
6882 if (TEST_BIT (ae_gen[bb->index], ptr->index))
6884 /* Find previous store. */
6886 for (st = AVAIL_STORE_LIST (ptr); st ; st = XEXP (st, 1))
6887 if (BLOCK_FOR_INSN (XEXP (st, 0)) == bb)
6891 rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
6893 fprintf (gcse_file, "Removing redundant store:\n");
6894 replace_store_insn (r, XEXP (st, 0), bb);
6895 XEXP (st, 0) = insn;
6899 SET_BIT (ae_gen[bb->index], ptr->index);
6900 AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn,
6901 AVAIL_STORE_LIST (ptr));
6904 if (!store_killed_before (ptr->pattern, insn, bb))
6906 SET_BIT (st_antloc[BLOCK_NUM (insn)], ptr->index);
6907 ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (insn,
6908 ANTIC_STORE_LIST (ptr));
6912 /* Free the original list of store insns. */
6913 free_INSN_LIST_list (&store_list);
6916 ae_kill = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
6917 sbitmap_vector_zero (ae_kill, last_basic_block);
6919 transp = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
6920 sbitmap_vector_zero (transp, last_basic_block);
6922 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6925 if (store_killed_after (ptr->pattern, b->head, b))
6927 /* The anticipatable expression is not killed if it's gen'd. */
6929 We leave this check out for now. If we have a code sequence
6930 in a block which looks like:
6934 We should flag this as having an ANTIC expression, NOT
6935 transparent, NOT killed, and AVAIL.
6936 Unfortunately, since we haven't re-written all loads to
6937 use the reaching reg, we'll end up doing an incorrect
6938 Load in the middle here if we push the store down. It happens in
6939 gcc.c-torture/execute/960311-1.c with -O3
6940 If we always kill it in this case, we'll sometimes do
6941 uneccessary work, but it shouldn't actually hurt anything.
6942 if (!TEST_BIT (ae_gen[b], ptr->index)). */
6943 SET_BIT (ae_kill[b->index], ptr->index);
6946 SET_BIT (transp[b->index], ptr->index);
6949 /* Any block with no exits calls some non-returning function, so
6950 we better mark the store killed here, or we might not store to
6951 it at all. If we knew it was abort, we wouldn't have to store,
6952 but we don't know that for sure. */
6955 fprintf (gcse_file, "ST_avail and ST_antic (shown under loads..)\n");
6956 print_ldst_list (gcse_file);
6957 dump_sbitmap_vector (gcse_file, "st_antloc", "", st_antloc, last_basic_block);
6958 dump_sbitmap_vector (gcse_file, "st_kill", "", ae_kill, last_basic_block);
6959 dump_sbitmap_vector (gcse_file, "Transpt", "", transp, last_basic_block);
6960 dump_sbitmap_vector (gcse_file, "st_avloc", "", ae_gen, last_basic_block);
6964 /* Insert an instruction at the begining of a basic block, and update
6965 the BLOCK_HEAD if needed. */
6968 insert_insn_start_bb (insn, bb)
6972 /* Insert at start of successor block. */
6973 rtx prev = PREV_INSN (bb->head);
6974 rtx before = bb->head;
6977 if (GET_CODE (before) != CODE_LABEL
6978 && (GET_CODE (before) != NOTE
6979 || NOTE_LINE_NUMBER (before) != NOTE_INSN_BASIC_BLOCK))
6982 if (prev == bb->end)
6984 before = NEXT_INSN (before);
6987 insn = emit_insn_after (insn, prev);
6991 fprintf (gcse_file, "STORE_MOTION insert store at start of BB %d:\n",
6993 print_inline_rtx (gcse_file, insn, 6);
6994 fprintf (gcse_file, "\n");
6998 /* This routine will insert a store on an edge. EXPR is the ldst entry for
6999 the memory reference, and E is the edge to insert it on. Returns non-zero
7000 if an edge insertion was performed. */
7003 insert_store (expr, e)
7004 struct ls_expr * expr;
7011 /* We did all the deleted before this insert, so if we didn't delete a
7012 store, then we haven't set the reaching reg yet either. */
7013 if (expr->reaching_reg == NULL_RTX)
7016 reg = expr->reaching_reg;
7017 insn = gen_move_insn (expr->pattern, reg);
7019 /* If we are inserting this expression on ALL predecessor edges of a BB,
7020 insert it at the start of the BB, and reset the insert bits on the other
7021 edges so we don't try to insert it on the other edges. */
7023 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
7025 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
7026 if (index == EDGE_INDEX_NO_EDGE)
7028 if (! TEST_BIT (pre_insert_map[index], expr->index))
7032 /* If tmp is NULL, we found an insertion on every edge, blank the
7033 insertion vector for these edges, and insert at the start of the BB. */
7034 if (!tmp && bb != EXIT_BLOCK_PTR)
7036 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
7038 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
7039 RESET_BIT (pre_insert_map[index], expr->index);
7041 insert_insn_start_bb (insn, bb);
7045 /* We can't insert on this edge, so we'll insert at the head of the
7046 successors block. See Morgan, sec 10.5. */
7047 if ((e->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
7049 insert_insn_start_bb (insn, bb);
7053 insert_insn_on_edge (insn, e);
7057 fprintf (gcse_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
7058 e->src->index, e->dest->index);
7059 print_inline_rtx (gcse_file, insn, 6);
7060 fprintf (gcse_file, "\n");
7066 /* This routine will replace a store with a SET to a specified register. */
7069 replace_store_insn (reg, del, bb)
7075 insn = gen_move_insn (reg, SET_SRC (PATTERN (del)));
7076 insn = emit_insn_after (insn, del);
7081 "STORE_MOTION delete insn in BB %d:\n ", bb->index);
7082 print_inline_rtx (gcse_file, del, 6);
7083 fprintf (gcse_file, "\nSTORE MOTION replaced with insn:\n ");
7084 print_inline_rtx (gcse_file, insn, 6);
7085 fprintf (gcse_file, "\n");
7092 /* Delete a store, but copy the value that would have been stored into
7093 the reaching_reg for later storing. */
7096 delete_store (expr, bb)
7097 struct ls_expr * expr;
7102 if (expr->reaching_reg == NULL_RTX)
7103 expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
7106 /* If there is more than 1 store, the earlier ones will be dead,
7107 but it doesn't hurt to replace them here. */
7108 reg = expr->reaching_reg;
7110 for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
7113 if (BLOCK_FOR_INSN (del) == bb)
7115 /* We know there is only one since we deleted redundant
7116 ones during the available computation. */
7117 replace_store_insn (reg, del, bb);
7123 /* Free memory used by store motion. */
7126 free_store_memory ()
7131 sbitmap_vector_free (ae_gen);
7133 sbitmap_vector_free (ae_kill);
7135 sbitmap_vector_free (transp);
7137 sbitmap_vector_free (st_antloc);
7139 sbitmap_vector_free (pre_insert_map);
7141 sbitmap_vector_free (pre_delete_map);
7142 if (reg_set_in_block)
7143 sbitmap_vector_free (reg_set_in_block);
7145 ae_gen = ae_kill = transp = st_antloc = NULL;
7146 pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
7149 /* Perform store motion. Much like gcse, except we move expressions the
7150 other way by looking at the flowgraph in reverse. */
7157 struct ls_expr * ptr;
7158 int update_flow = 0;
7162 fprintf (gcse_file, "before store motion\n");
7163 print_rtl (gcse_file, get_insns ());
7167 init_alias_analysis ();
7169 /* Find all the stores that are live to the end of their block. */
7170 num_stores = compute_store_table ();
7171 if (num_stores == 0)
7173 sbitmap_vector_free (reg_set_in_block);
7174 end_alias_analysis ();
7178 /* Now compute whats actually available to move. */
7179 add_noreturn_fake_exit_edges ();
7180 build_store_vectors ();
7182 edge_list = pre_edge_rev_lcm (gcse_file, num_stores, transp, ae_gen,
7183 st_antloc, ae_kill, &pre_insert_map,
7186 /* Now we want to insert the new stores which are going to be needed. */
7187 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7190 if (TEST_BIT (pre_delete_map[bb->index], ptr->index))
7191 delete_store (ptr, bb);
7193 for (x = 0; x < NUM_EDGES (edge_list); x++)
7194 if (TEST_BIT (pre_insert_map[x], ptr->index))
7195 update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
7199 commit_edge_insertions ();
7201 free_store_memory ();
7202 free_edge_list (edge_list);
7203 remove_fake_edges ();
7204 end_alias_analysis ();