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"
169 /* We don't want to use xmalloc. */
170 #undef obstack_chunk_alloc
171 #define obstack_chunk_alloc gmalloc
173 /* Propagate flow information through back edges and thus enable PRE's
174 moving loop invariant calculations out of loops.
176 Originally this tended to create worse overall code, but several
177 improvements during the development of PRE seem to have made following
178 back edges generally a win.
180 Note much of the loop invariant code motion done here would normally
181 be done by loop.c, which has more heuristics for when to move invariants
182 out of loops. At some point we might need to move some of those
183 heuristics into gcse.c. */
185 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
186 are a superset of those done by GCSE.
188 We perform the following steps:
190 1) Compute basic block information.
192 2) Compute table of places where registers are set.
194 3) Perform copy/constant propagation.
196 4) Perform global cse.
198 5) Perform another pass of copy/constant propagation.
200 Two passes of copy/constant propagation are done because the first one
201 enables more GCSE and the second one helps to clean up the copies that
202 GCSE creates. This is needed more for PRE than for Classic because Classic
203 GCSE will try to use an existing register containing the common
204 subexpression rather than create a new one. This is harder to do for PRE
205 because of the code motion (which Classic GCSE doesn't do).
207 Expressions we are interested in GCSE-ing are of the form
208 (set (pseudo-reg) (expression)).
209 Function want_to_gcse_p says what these are.
211 PRE handles moving invariant expressions out of loops (by treating them as
212 partially redundant).
214 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
215 assignment) based GVN (global value numbering). L. T. Simpson's paper
216 (Rice University) on value numbering is a useful reference for this.
218 **********************
220 We used to support multiple passes but there are diminishing returns in
221 doing so. The first pass usually makes 90% of the changes that are doable.
222 A second pass can make a few more changes made possible by the first pass.
223 Experiments show any further passes don't make enough changes to justify
226 A study of spec92 using an unlimited number of passes:
227 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
228 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
229 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
231 It was found doing copy propagation between each pass enables further
234 PRE is quite expensive in complicated functions because the DFA can take
235 awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can
236 be modified if one wants to experiment.
238 **********************
240 The steps for PRE are:
242 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
244 2) Perform the data flow analysis for PRE.
246 3) Delete the redundant instructions
248 4) Insert the required copies [if any] that make the partially
249 redundant instructions fully redundant.
251 5) For other reaching expressions, insert an instruction to copy the value
252 to a newly created pseudo that will reach the redundant instruction.
254 The deletion is done first so that when we do insertions we
255 know which pseudo reg to use.
257 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
258 argue it is not. The number of iterations for the algorithm to converge
259 is typically 2-4 so I don't view it as that expensive (relatively speaking).
261 PRE GCSE depends heavily on the second CSE pass to clean up the copies
262 we create. To make an expression reach the place where it's redundant,
263 the result of the expression is copied to a new register, and the redundant
264 expression is deleted by replacing it with this new register. Classic GCSE
265 doesn't have this problem as much as it computes the reaching defs of
266 each register in each block and thus can try to use an existing register.
268 **********************
270 A fair bit of simplicity is created by creating small functions for simple
271 tasks, even when the function is only called in one place. This may
272 measurably slow things down [or may not] by creating more function call
273 overhead than is necessary. The source is laid out so that it's trivial
274 to make the affected functions inline so that one can measure what speed
275 up, if any, can be achieved, and maybe later when things settle things can
278 Help stamp out big monolithic functions! */
280 /* GCSE global vars. */
283 static FILE *gcse_file;
285 /* Note whether or not we should run jump optimization after gcse. We
286 want to do this for two cases.
288 * If we changed any jumps via cprop.
290 * If we added any labels via edge splitting. */
292 static int run_jump_opt_after_gcse;
294 /* Bitmaps are normally not included in debugging dumps.
295 However it's useful to be able to print them from GDB.
296 We could create special functions for this, but it's simpler to
297 just allow passing stderr to the dump_foo fns. Since stderr can
298 be a macro, we store a copy here. */
299 static FILE *debug_stderr;
301 /* An obstack for our working variables. */
302 static struct obstack gcse_obstack;
304 /* Non-zero for each mode that supports (set (reg) (reg)).
305 This is trivially true for integer and floating point values.
306 It may or may not be true for condition codes. */
307 static char can_copy_p[(int) NUM_MACHINE_MODES];
309 /* Non-zero if can_copy_p has been initialized. */
310 static int can_copy_init_p;
312 struct reg_use {rtx reg_rtx; };
314 /* Hash table of expressions. */
318 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
320 /* Index in the available expression bitmaps. */
322 /* Next entry with the same hash. */
323 struct expr *next_same_hash;
324 /* List of anticipatable occurrences in basic blocks in the function.
325 An "anticipatable occurrence" is one that is the first occurrence in the
326 basic block, the operands are not modified in the basic block prior
327 to the occurrence and the output is not used between the start of
328 the block and the occurrence. */
329 struct occr *antic_occr;
330 /* List of available occurrence in basic blocks in the function.
331 An "available occurrence" is one that is the last occurrence in the
332 basic block and the operands are not modified by following statements in
333 the basic block [including this insn]. */
334 struct occr *avail_occr;
335 /* Non-null if the computation is PRE redundant.
336 The value is the newly created pseudo-reg to record a copy of the
337 expression in all the places that reach the redundant copy. */
341 /* Occurrence of an expression.
342 There is one per basic block. If a pattern appears more than once the
343 last appearance is used [or first for anticipatable expressions]. */
347 /* Next occurrence of this expression. */
349 /* The insn that computes the expression. */
351 /* Non-zero if this [anticipatable] occurrence has been deleted. */
353 /* Non-zero if this [available] occurrence has been copied to
355 /* ??? This is mutually exclusive with deleted_p, so they could share
360 /* Expression and copy propagation hash tables.
361 Each hash table is an array of buckets.
362 ??? It is known that if it were an array of entries, structure elements
363 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
364 not clear whether in the final analysis a sufficient amount of memory would
365 be saved as the size of the available expression bitmaps would be larger
366 [one could build a mapping table without holes afterwards though].
367 Someday I'll perform the computation and figure it out. */
369 /* Total size of the expression hash table, in elements. */
370 static unsigned int expr_hash_table_size;
373 This is an array of `expr_hash_table_size' elements. */
374 static struct expr **expr_hash_table;
376 /* Total size of the copy propagation hash table, in elements. */
377 static unsigned int set_hash_table_size;
380 This is an array of `set_hash_table_size' elements. */
381 static struct expr **set_hash_table;
383 /* Mapping of uids to cuids.
384 Only real insns get cuids. */
385 static int *uid_cuid;
387 /* Highest UID in UID_CUID. */
390 /* Get the cuid of an insn. */
391 #ifdef ENABLE_CHECKING
392 #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
394 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
397 /* Number of cuids. */
400 /* Mapping of cuids to insns. */
401 static rtx *cuid_insn;
403 /* Get insn from cuid. */
404 #define CUID_INSN(CUID) (cuid_insn[CUID])
406 /* Maximum register number in function prior to doing gcse + 1.
407 Registers created during this pass have regno >= max_gcse_regno.
408 This is named with "gcse" to not collide with global of same name. */
409 static unsigned int max_gcse_regno;
411 /* Maximum number of cse-able expressions found. */
414 /* Maximum number of assignments for copy propagation found. */
417 /* Table of registers that are modified.
419 For each register, each element is a list of places where the pseudo-reg
422 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
423 requires knowledge of which blocks kill which regs [and thus could use
424 a bitmap instead of the lists `reg_set_table' uses].
426 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
427 num-regs) [however perhaps it may be useful to keep the data as is]. One
428 advantage of recording things this way is that `reg_set_table' is fairly
429 sparse with respect to pseudo regs but for hard regs could be fairly dense
430 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
431 up functions like compute_transp since in the case of pseudo-regs we only
432 need to iterate over the number of times a pseudo-reg is set, not over the
433 number of basic blocks [clearly there is a bit of a slow down in the cases
434 where a pseudo is set more than once in a block, however it is believed
435 that the net effect is to speed things up]. This isn't done for hard-regs
436 because recording call-clobbered hard-regs in `reg_set_table' at each
437 function call can consume a fair bit of memory, and iterating over
438 hard-regs stored this way in compute_transp will be more expensive. */
440 typedef struct reg_set
442 /* The next setting of this register. */
443 struct reg_set *next;
444 /* The insn where it was set. */
448 static reg_set **reg_set_table;
450 /* Size of `reg_set_table'.
451 The table starts out at max_gcse_regno + slop, and is enlarged as
453 static int reg_set_table_size;
455 /* Amount to grow `reg_set_table' by when it's full. */
456 #define REG_SET_TABLE_SLOP 100
458 /* This is a list of expressions which are MEMs and will be used by load
460 Load motion tracks MEMs which aren't killed by
461 anything except itself. (ie, loads and stores to a single location).
462 We can then allow movement of these MEM refs with a little special
463 allowance. (all stores copy the same value to the reaching reg used
464 for the loads). This means all values used to store into memory must have
465 no side effects so we can re-issue the setter value.
466 Store Motion uses this structure as an expression table to track stores
467 which look interesting, and might be moveable towards the exit block. */
471 struct expr * expr; /* Gcse expression reference for LM. */
472 rtx pattern; /* Pattern of this mem. */
473 rtx loads; /* INSN list of loads seen. */
474 rtx stores; /* INSN list of stores seen. */
475 struct ls_expr * next; /* Next in the list. */
476 int invalid; /* Invalid for some reason. */
477 int index; /* If it maps to a bitmap index. */
478 int hash_index; /* Index when in a hash table. */
479 rtx reaching_reg; /* Register to use when re-writing. */
482 /* Head of the list of load/store memory refs. */
483 static struct ls_expr * pre_ldst_mems = NULL;
485 /* Bitmap containing one bit for each register in the program.
486 Used when performing GCSE to track which registers have been set since
487 the start of the basic block. */
488 static regset reg_set_bitmap;
490 /* For each block, a bitmap of registers set in the block.
491 This is used by expr_killed_p and compute_transp.
492 It is computed during hash table computation and not by compute_sets
493 as it includes registers added since the last pass (or between cprop and
494 gcse) and it's currently not easy to realloc sbitmap vectors. */
495 static sbitmap *reg_set_in_block;
497 /* Array, indexed by basic block number for a list of insns which modify
498 memory within that block. */
499 static rtx * modify_mem_list;
500 bitmap modify_mem_list_set;
502 /* This array parallels modify_mem_list, but is kept canonicalized. */
503 static rtx * canon_modify_mem_list;
504 bitmap canon_modify_mem_list_set;
505 /* Various variables for statistics gathering. */
507 /* Memory used in a pass.
508 This isn't intended to be absolutely precise. Its intent is only
509 to keep an eye on memory usage. */
510 static int bytes_used;
512 /* GCSE substitutions made. */
513 static int gcse_subst_count;
514 /* Number of copy instructions created. */
515 static int gcse_create_count;
516 /* Number of constants propagated. */
517 static int const_prop_count;
518 /* Number of copys propagated. */
519 static int copy_prop_count;
521 /* These variables are used by classic GCSE.
522 Normally they'd be defined a bit later, but `rd_gen' needs to
523 be declared sooner. */
525 /* Each block has a bitmap of each type.
526 The length of each blocks bitmap is:
528 max_cuid - for reaching definitions
529 n_exprs - for available expressions
531 Thus we view the bitmaps as 2 dimensional arrays. i.e.
532 rd_kill[block_num][cuid_num]
533 ae_kill[block_num][expr_num] */
535 /* For reaching defs */
536 static sbitmap *rd_kill, *rd_gen, *reaching_defs, *rd_out;
538 /* for available exprs */
539 static sbitmap *ae_kill, *ae_gen, *ae_in, *ae_out;
541 /* Objects of this type are passed around by the null-pointer check
543 struct null_pointer_info
545 /* The basic block being processed. */
546 basic_block current_block;
547 /* The first register to be handled in this pass. */
548 unsigned int min_reg;
549 /* One greater than the last register to be handled in this pass. */
550 unsigned int max_reg;
551 sbitmap *nonnull_local;
552 sbitmap *nonnull_killed;
555 static void compute_can_copy PARAMS ((void));
556 static char *gmalloc PARAMS ((unsigned int));
557 static char *grealloc PARAMS ((char *, unsigned int));
558 static char *gcse_alloc PARAMS ((unsigned long));
559 static void alloc_gcse_mem PARAMS ((rtx));
560 static void free_gcse_mem PARAMS ((void));
561 static void alloc_reg_set_mem PARAMS ((int));
562 static void free_reg_set_mem PARAMS ((void));
563 static int get_bitmap_width PARAMS ((int, int, int));
564 static void record_one_set PARAMS ((int, rtx));
565 static void record_set_info PARAMS ((rtx, rtx, void *));
566 static void compute_sets PARAMS ((rtx));
567 static void hash_scan_insn PARAMS ((rtx, int, int));
568 static void hash_scan_set PARAMS ((rtx, rtx, int));
569 static void hash_scan_clobber PARAMS ((rtx, rtx));
570 static void hash_scan_call PARAMS ((rtx, rtx));
571 static int want_to_gcse_p PARAMS ((rtx));
572 static int oprs_unchanged_p PARAMS ((rtx, rtx, int));
573 static int oprs_anticipatable_p PARAMS ((rtx, rtx));
574 static int oprs_available_p PARAMS ((rtx, rtx));
575 static void insert_expr_in_table PARAMS ((rtx, enum machine_mode, rtx,
577 static void insert_set_in_table PARAMS ((rtx, rtx));
578 static unsigned int hash_expr PARAMS ((rtx, enum machine_mode, int *, int));
579 static unsigned int hash_expr_1 PARAMS ((rtx, enum machine_mode, int *));
580 static unsigned int hash_string_1 PARAMS ((const char *));
581 static unsigned int hash_set PARAMS ((int, int));
582 static int expr_equiv_p PARAMS ((rtx, rtx));
583 static void record_last_reg_set_info PARAMS ((rtx, int));
584 static void record_last_mem_set_info PARAMS ((rtx));
585 static void record_last_set_info PARAMS ((rtx, rtx, void *));
586 static void compute_hash_table PARAMS ((int));
587 static void alloc_set_hash_table PARAMS ((int));
588 static void free_set_hash_table PARAMS ((void));
589 static void compute_set_hash_table PARAMS ((void));
590 static void alloc_expr_hash_table PARAMS ((unsigned int));
591 static void free_expr_hash_table PARAMS ((void));
592 static void compute_expr_hash_table PARAMS ((void));
593 static void dump_hash_table PARAMS ((FILE *, const char *, struct expr **,
595 static struct expr *lookup_expr PARAMS ((rtx));
596 static struct expr *lookup_set PARAMS ((unsigned int, rtx));
597 static struct expr *next_set PARAMS ((unsigned int, struct expr *));
598 static void reset_opr_set_tables PARAMS ((void));
599 static int oprs_not_set_p PARAMS ((rtx, rtx));
600 static void mark_call PARAMS ((rtx));
601 static void mark_set PARAMS ((rtx, rtx));
602 static void mark_clobber PARAMS ((rtx, rtx));
603 static void mark_oprs_set PARAMS ((rtx));
604 static void alloc_cprop_mem PARAMS ((int, int));
605 static void free_cprop_mem PARAMS ((void));
606 static void compute_transp PARAMS ((rtx, int, sbitmap *, int));
607 static void compute_transpout PARAMS ((void));
608 static void compute_local_properties PARAMS ((sbitmap *, sbitmap *, sbitmap *,
610 static void compute_cprop_data PARAMS ((void));
611 static void find_used_regs PARAMS ((rtx *, void *));
612 static int try_replace_reg PARAMS ((rtx, rtx, rtx));
613 static struct expr *find_avail_set PARAMS ((int, rtx));
614 static int cprop_jump PARAMS ((basic_block, rtx, rtx, rtx, rtx));
615 static void mems_conflict_for_gcse_p PARAMS ((rtx, rtx, void *));
616 static int load_killed_in_block_p PARAMS ((basic_block, int, rtx, int));
617 static void canon_list_insert PARAMS ((rtx, rtx, void *));
618 static int cprop_insn PARAMS ((rtx, int));
619 static int cprop PARAMS ((int));
620 static int one_cprop_pass PARAMS ((int, int));
621 static bool constprop_register PARAMS ((rtx, rtx, rtx, int));
622 static struct expr *find_bypass_set PARAMS ((int, int));
623 static int bypass_block PARAMS ((basic_block, rtx, rtx));
624 static int bypass_conditional_jumps PARAMS ((void));
625 static void alloc_pre_mem PARAMS ((int, int));
626 static void free_pre_mem PARAMS ((void));
627 static void compute_pre_data PARAMS ((void));
628 static int pre_expr_reaches_here_p PARAMS ((basic_block, struct expr *,
630 static void insert_insn_end_bb PARAMS ((struct expr *, basic_block, int));
631 static void pre_insert_copy_insn PARAMS ((struct expr *, rtx));
632 static void pre_insert_copies PARAMS ((void));
633 static int pre_delete PARAMS ((void));
634 static int pre_gcse PARAMS ((void));
635 static int one_pre_gcse_pass PARAMS ((int));
636 static void add_label_notes PARAMS ((rtx, rtx));
637 static void alloc_code_hoist_mem PARAMS ((int, int));
638 static void free_code_hoist_mem PARAMS ((void));
639 static void compute_code_hoist_vbeinout PARAMS ((void));
640 static void compute_code_hoist_data PARAMS ((void));
641 static int hoist_expr_reaches_here_p PARAMS ((basic_block, int, basic_block,
643 static void hoist_code PARAMS ((void));
644 static int one_code_hoisting_pass PARAMS ((void));
645 static void alloc_rd_mem PARAMS ((int, int));
646 static void free_rd_mem PARAMS ((void));
647 static void handle_rd_kill_set PARAMS ((rtx, int, basic_block));
648 static void compute_kill_rd PARAMS ((void));
649 static void compute_rd PARAMS ((void));
650 static void alloc_avail_expr_mem PARAMS ((int, int));
651 static void free_avail_expr_mem PARAMS ((void));
652 static void compute_ae_gen PARAMS ((void));
653 static int expr_killed_p PARAMS ((rtx, basic_block));
654 static void compute_ae_kill PARAMS ((sbitmap *, sbitmap *));
655 static int expr_reaches_here_p PARAMS ((struct occr *, struct expr *,
657 static rtx computing_insn PARAMS ((struct expr *, rtx));
658 static int def_reaches_here_p PARAMS ((rtx, rtx));
659 static int can_disregard_other_sets PARAMS ((struct reg_set **, rtx, int));
660 static int handle_avail_expr PARAMS ((rtx, struct expr *));
661 static int classic_gcse PARAMS ((void));
662 static int one_classic_gcse_pass PARAMS ((int));
663 static void invalidate_nonnull_info PARAMS ((rtx, rtx, void *));
664 static int delete_null_pointer_checks_1 PARAMS ((unsigned int *,
665 sbitmap *, sbitmap *,
666 struct null_pointer_info *));
667 static rtx process_insert_insn PARAMS ((struct expr *));
668 static int pre_edge_insert PARAMS ((struct edge_list *, struct expr **));
669 static int expr_reaches_here_p_work PARAMS ((struct occr *, struct expr *,
670 basic_block, int, char *));
671 static int pre_expr_reaches_here_p_work PARAMS ((basic_block, struct expr *,
672 basic_block, char *));
673 static struct ls_expr * ldst_entry PARAMS ((rtx));
674 static void free_ldst_entry PARAMS ((struct ls_expr *));
675 static void free_ldst_mems PARAMS ((void));
676 static void print_ldst_list PARAMS ((FILE *));
677 static struct ls_expr * find_rtx_in_ldst PARAMS ((rtx));
678 static int enumerate_ldsts PARAMS ((void));
679 static inline struct ls_expr * first_ls_expr PARAMS ((void));
680 static inline struct ls_expr * next_ls_expr PARAMS ((struct ls_expr *));
681 static int simple_mem PARAMS ((rtx));
682 static void invalidate_any_buried_refs PARAMS ((rtx));
683 static void compute_ld_motion_mems PARAMS ((void));
684 static void trim_ld_motion_mems PARAMS ((void));
685 static void update_ld_motion_stores PARAMS ((struct expr *));
686 static void reg_set_info PARAMS ((rtx, rtx, void *));
687 static int store_ops_ok PARAMS ((rtx, basic_block));
688 static void find_moveable_store PARAMS ((rtx));
689 static int compute_store_table PARAMS ((void));
690 static int load_kills_store PARAMS ((rtx, rtx));
691 static int find_loads PARAMS ((rtx, rtx));
692 static int store_killed_in_insn PARAMS ((rtx, rtx));
693 static int store_killed_after PARAMS ((rtx, rtx, basic_block));
694 static int store_killed_before PARAMS ((rtx, rtx, basic_block));
695 static void build_store_vectors PARAMS ((void));
696 static void insert_insn_start_bb PARAMS ((rtx, basic_block));
697 static int insert_store PARAMS ((struct ls_expr *, edge));
698 static void replace_store_insn PARAMS ((rtx, rtx, basic_block));
699 static void delete_store PARAMS ((struct ls_expr *,
701 static void free_store_memory PARAMS ((void));
702 static void store_motion PARAMS ((void));
703 static void free_insn_expr_list_list PARAMS ((rtx *));
704 static void clear_modify_mem_tables PARAMS ((void));
705 static void free_modify_mem_tables PARAMS ((void));
706 static rtx gcse_emit_move_after PARAMS ((rtx, rtx, rtx));
707 static bool do_local_cprop PARAMS ((rtx, rtx, int));
708 static void local_cprop_pass PARAMS ((int));
710 /* Entry point for global common subexpression elimination.
711 F is the first instruction in the function. */
719 /* Bytes used at start of pass. */
720 int initial_bytes_used;
721 /* Maximum number of bytes used by a pass. */
723 /* Point to release obstack data from for each pass. */
724 char *gcse_obstack_bottom;
726 /* Insertion of instructions on edges can create new basic blocks; we
727 need the original basic block count so that we can properly deallocate
728 arrays sized on the number of basic blocks originally in the cfg. */
730 /* We do not construct an accurate cfg in functions which call
731 setjmp, so just punt to be safe. */
732 if (current_function_calls_setjmp)
735 /* Assume that we do not need to run jump optimizations after gcse. */
736 run_jump_opt_after_gcse = 0;
738 /* For calling dump_foo fns from gdb. */
739 debug_stderr = stderr;
742 /* Identify the basic block information for this function, including
743 successors and predecessors. */
744 max_gcse_regno = max_reg_num ();
747 dump_flow_info (file);
749 orig_bb_count = n_basic_blocks;
750 /* Return if there's nothing to do. */
751 if (n_basic_blocks <= 1)
754 /* Trying to perform global optimizations on flow graphs which have
755 a high connectivity will take a long time and is unlikely to be
758 In normal circumstances a cfg should have about twice as many edges
759 as blocks. But we do not want to punish small functions which have
760 a couple switch statements. So we require a relatively large number
761 of basic blocks and the ratio of edges to blocks to be high. */
762 if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
764 if (warn_disabled_optimization)
765 warning ("GCSE disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
766 n_basic_blocks, n_edges / n_basic_blocks);
770 /* If allocating memory for the cprop bitmap would take up too much
771 storage it's better just to disable the optimization. */
773 * SBITMAP_SET_SIZE (max_gcse_regno)
774 * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
776 if (warn_disabled_optimization)
777 warning ("GCSE disabled: %d basic blocks and %d registers",
778 n_basic_blocks, max_gcse_regno);
783 /* See what modes support reg/reg copy operations. */
784 if (! can_copy_init_p)
790 gcc_obstack_init (&gcse_obstack);
794 init_alias_analysis ();
795 /* Record where pseudo-registers are set. This data is kept accurate
796 during each pass. ??? We could also record hard-reg information here
797 [since it's unchanging], however it is currently done during hash table
800 It may be tempting to compute MEM set information here too, but MEM sets
801 will be subject to code motion one day and thus we need to compute
802 information about memory sets when we build the hash tables. */
804 alloc_reg_set_mem (max_gcse_regno);
808 initial_bytes_used = bytes_used;
810 gcse_obstack_bottom = gcse_alloc (1);
812 while (changed && pass < MAX_GCSE_PASSES)
816 fprintf (file, "GCSE pass %d\n\n", pass + 1);
818 /* Initialize bytes_used to the space for the pred/succ lists,
819 and the reg_set_table data. */
820 bytes_used = initial_bytes_used;
822 /* Each pass may create new registers, so recalculate each time. */
823 max_gcse_regno = max_reg_num ();
827 /* Don't allow constant propagation to modify jumps
829 changed = one_cprop_pass (pass + 1, 0);
832 changed |= one_classic_gcse_pass (pass + 1);
835 changed |= one_pre_gcse_pass (pass + 1);
836 /* We may have just created new basic blocks. Release and
837 recompute various things which are sized on the number of
841 free_modify_mem_tables ();
843 = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
844 canon_modify_mem_list
845 = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
846 memset ((char *) modify_mem_list, 0, last_basic_block * sizeof (rtx));
847 memset ((char *) canon_modify_mem_list, 0, last_basic_block * sizeof (rtx));
848 orig_bb_count = n_basic_blocks;
851 alloc_reg_set_mem (max_reg_num ());
853 run_jump_opt_after_gcse = 1;
856 if (max_pass_bytes < bytes_used)
857 max_pass_bytes = bytes_used;
859 /* Free up memory, then reallocate for code hoisting. We can
860 not re-use the existing allocated memory because the tables
861 will not have info for the insns or registers created by
862 partial redundancy elimination. */
865 /* It does not make sense to run code hoisting unless we optimizing
866 for code size -- it rarely makes programs faster, and can make
867 them bigger if we did partial redundancy elimination (when optimizing
868 for space, we use a classic gcse algorithm instead of partial
869 redundancy algorithms). */
872 max_gcse_regno = max_reg_num ();
874 changed |= one_code_hoisting_pass ();
877 if (max_pass_bytes < bytes_used)
878 max_pass_bytes = bytes_used;
883 fprintf (file, "\n");
887 obstack_free (&gcse_obstack, gcse_obstack_bottom);
891 /* Do one last pass of copy propagation, including cprop into
892 conditional jumps. */
894 max_gcse_regno = max_reg_num ();
896 /* This time, go ahead and allow cprop to alter jumps. */
897 one_cprop_pass (pass + 1, 1);
902 fprintf (file, "GCSE of %s: %d basic blocks, ",
903 current_function_name, n_basic_blocks);
904 fprintf (file, "%d pass%s, %d bytes\n\n",
905 pass, pass > 1 ? "es" : "", max_pass_bytes);
908 obstack_free (&gcse_obstack, NULL);
910 /* We are finished with alias. */
911 end_alias_analysis ();
912 allocate_reg_info (max_reg_num (), FALSE, FALSE);
914 /* Store motion disabled until it is fixed. */
915 if (0 && !optimize_size && flag_gcse_sm)
917 /* Record where pseudo-registers are set. */
918 return run_jump_opt_after_gcse;
921 /* Misc. utilities. */
923 /* Compute which modes support reg/reg copy operations. */
929 #ifndef AVOID_CCMODE_COPIES
932 memset (can_copy_p, 0, NUM_MACHINE_MODES);
935 for (i = 0; i < NUM_MACHINE_MODES; i++)
936 if (GET_MODE_CLASS (i) == MODE_CC)
938 #ifdef AVOID_CCMODE_COPIES
941 reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1);
942 insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
943 if (recog (PATTERN (insn), insn, NULL) >= 0)
953 /* Cover function to xmalloc to record bytes allocated. */
960 return xmalloc (size);
963 /* Cover function to xrealloc.
964 We don't record the additional size since we don't know it.
965 It won't affect memory usage stats much anyway. */
972 return xrealloc (ptr, size);
975 /* Cover function to obstack_alloc.
976 We don't need to record the bytes allocated here since
977 obstack_chunk_alloc is set to gmalloc. */
983 return (char *) obstack_alloc (&gcse_obstack, size);
986 /* Allocate memory for the cuid mapping array,
987 and reg/memory set tracking tables.
989 This is called at the start of each pass. */
998 /* Find the largest UID and create a mapping from UIDs to CUIDs.
999 CUIDs are like UIDs except they increase monotonically, have no gaps,
1000 and only apply to real insns. */
1002 max_uid = get_max_uid ();
1003 n = (max_uid + 1) * sizeof (int);
1004 uid_cuid = (int *) gmalloc (n);
1005 memset ((char *) uid_cuid, 0, n);
1006 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
1009 uid_cuid[INSN_UID (insn)] = i++;
1011 uid_cuid[INSN_UID (insn)] = i;
1014 /* Create a table mapping cuids to insns. */
1017 n = (max_cuid + 1) * sizeof (rtx);
1018 cuid_insn = (rtx *) gmalloc (n);
1019 memset ((char *) cuid_insn, 0, n);
1020 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
1022 CUID_INSN (i++) = insn;
1024 /* Allocate vars to track sets of regs. */
1025 reg_set_bitmap = BITMAP_XMALLOC ();
1027 /* Allocate vars to track sets of regs, memory per block. */
1028 reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (last_basic_block,
1030 /* Allocate array to keep a list of insns which modify memory in each
1032 modify_mem_list = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
1033 canon_modify_mem_list = (rtx *) gmalloc (last_basic_block * sizeof (rtx));
1034 memset ((char *) modify_mem_list, 0, last_basic_block * sizeof (rtx));
1035 memset ((char *) canon_modify_mem_list, 0, last_basic_block * sizeof (rtx));
1036 modify_mem_list_set = BITMAP_XMALLOC ();
1037 canon_modify_mem_list_set = BITMAP_XMALLOC ();
1040 /* Free memory allocated by alloc_gcse_mem. */
1048 BITMAP_XFREE (reg_set_bitmap);
1050 sbitmap_vector_free (reg_set_in_block);
1051 free_modify_mem_tables ();
1052 BITMAP_XFREE (modify_mem_list_set);
1053 BITMAP_XFREE (canon_modify_mem_list_set);
1056 /* Many of the global optimization algorithms work by solving dataflow
1057 equations for various expressions. Initially, some local value is
1058 computed for each expression in each block. Then, the values across the
1059 various blocks are combined (by following flow graph edges) to arrive at
1060 global values. Conceptually, each set of equations is independent. We
1061 may therefore solve all the equations in parallel, solve them one at a
1062 time, or pick any intermediate approach.
1064 When you're going to need N two-dimensional bitmaps, each X (say, the
1065 number of blocks) by Y (say, the number of expressions), call this
1066 function. It's not important what X and Y represent; only that Y
1067 correspond to the things that can be done in parallel. This function will
1068 return an appropriate chunking factor C; you should solve C sets of
1069 equations in parallel. By going through this function, we can easily
1070 trade space against time; by solving fewer equations in parallel we use
1074 get_bitmap_width (n, x, y)
1079 /* It's not really worth figuring out *exactly* how much memory will
1080 be used by a particular choice. The important thing is to get
1081 something approximately right. */
1082 size_t max_bitmap_memory = 10 * 1024 * 1024;
1084 /* The number of bytes we'd use for a single column of minimum
1086 size_t column_size = n * x * sizeof (SBITMAP_ELT_TYPE);
1088 /* Often, it's reasonable just to solve all the equations in
1090 if (column_size * SBITMAP_SET_SIZE (y) <= max_bitmap_memory)
1093 /* Otherwise, pick the largest width we can, without going over the
1095 return SBITMAP_ELT_BITS * ((max_bitmap_memory + column_size - 1)
1099 /* Compute the local properties of each recorded expression.
1101 Local properties are those that are defined by the block, irrespective of
1104 An expression is transparent in a block if its operands are not modified
1107 An expression is computed (locally available) in a block if it is computed
1108 at least once and expression would contain the same value if the
1109 computation was moved to the end of the block.
1111 An expression is locally anticipatable in a block if it is computed at
1112 least once and expression would contain the same value if the computation
1113 was moved to the beginning of the block.
1115 We call this routine for cprop, pre and code hoisting. They all compute
1116 basically the same information and thus can easily share this code.
1118 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1119 properties. If NULL, then it is not necessary to compute or record that
1120 particular property.
1122 SETP controls which hash table to look at. If zero, this routine looks at
1123 the expr hash table; if nonzero this routine looks at the set hash table.
1124 Additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1128 compute_local_properties (transp, comp, antloc, setp)
1134 unsigned int i, hash_table_size;
1135 struct expr **hash_table;
1137 /* Initialize any bitmaps that were passed in. */
1141 sbitmap_vector_zero (transp, last_basic_block);
1143 sbitmap_vector_ones (transp, last_basic_block);
1147 sbitmap_vector_zero (comp, last_basic_block);
1149 sbitmap_vector_zero (antloc, last_basic_block);
1151 /* We use the same code for cprop, pre and hoisting. For cprop
1152 we care about the set hash table, for pre and hoisting we
1153 care about the expr hash table. */
1154 hash_table_size = setp ? set_hash_table_size : expr_hash_table_size;
1155 hash_table = setp ? set_hash_table : expr_hash_table;
1157 for (i = 0; i < hash_table_size; i++)
1161 for (expr = hash_table[i]; expr != NULL; expr = expr->next_same_hash)
1163 int indx = expr->bitmap_index;
1166 /* The expression is transparent in this block if it is not killed.
1167 We start by assuming all are transparent [none are killed], and
1168 then reset the bits for those that are. */
1170 compute_transp (expr->expr, indx, transp, setp);
1172 /* The occurrences recorded in antic_occr are exactly those that
1173 we want to set to non-zero in ANTLOC. */
1175 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
1177 SET_BIT (antloc[BLOCK_NUM (occr->insn)], indx);
1179 /* While we're scanning the table, this is a good place to
1181 occr->deleted_p = 0;
1184 /* The occurrences recorded in avail_occr are exactly those that
1185 we want to set to non-zero in COMP. */
1187 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
1189 SET_BIT (comp[BLOCK_NUM (occr->insn)], indx);
1191 /* While we're scanning the table, this is a good place to
1196 /* While we're scanning the table, this is a good place to
1198 expr->reaching_reg = 0;
1203 /* Register set information.
1205 `reg_set_table' records where each register is set or otherwise
1208 static struct obstack reg_set_obstack;
1211 alloc_reg_set_mem (n_regs)
1216 reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
1217 n = reg_set_table_size * sizeof (struct reg_set *);
1218 reg_set_table = (struct reg_set **) gmalloc (n);
1219 memset ((char *) reg_set_table, 0, n);
1221 gcc_obstack_init (®_set_obstack);
1227 free (reg_set_table);
1228 obstack_free (®_set_obstack, NULL);
1231 /* Record REGNO in the reg_set table. */
1234 record_one_set (regno, insn)
1238 /* Allocate a new reg_set element and link it onto the list. */
1239 struct reg_set *new_reg_info;
1241 /* If the table isn't big enough, enlarge it. */
1242 if (regno >= reg_set_table_size)
1244 int new_size = regno + REG_SET_TABLE_SLOP;
1247 = (struct reg_set **) grealloc ((char *) reg_set_table,
1248 new_size * sizeof (struct reg_set *));
1249 memset ((char *) (reg_set_table + reg_set_table_size), 0,
1250 (new_size - reg_set_table_size) * sizeof (struct reg_set *));
1251 reg_set_table_size = new_size;
1254 new_reg_info = (struct reg_set *) obstack_alloc (®_set_obstack,
1255 sizeof (struct reg_set));
1256 bytes_used += sizeof (struct reg_set);
1257 new_reg_info->insn = insn;
1258 new_reg_info->next = reg_set_table[regno];
1259 reg_set_table[regno] = new_reg_info;
1262 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1263 an insn. The DATA is really the instruction in which the SET is
1267 record_set_info (dest, setter, data)
1268 rtx dest, setter ATTRIBUTE_UNUSED;
1271 rtx record_set_insn = (rtx) data;
1273 if (GET_CODE (dest) == REG && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
1274 record_one_set (REGNO (dest), record_set_insn);
1277 /* Scan the function and record each set of each pseudo-register.
1279 This is called once, at the start of the gcse pass. See the comments for
1280 `reg_set_table' for further documenation. */
1288 for (insn = f; insn != 0; insn = NEXT_INSN (insn))
1290 note_stores (PATTERN (insn), record_set_info, insn);
1293 /* Hash table support. */
1295 struct reg_avail_info
1297 basic_block last_bb;
1302 static struct reg_avail_info *reg_avail_info;
1303 static basic_block current_bb;
1306 /* See whether X, the source of a set, is something we want to consider for
1309 static GTY(()) rtx test_insn;
1314 int num_clobbers = 0;
1317 switch (GET_CODE (x))
1331 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1332 if (general_operand (x, GET_MODE (x)))
1334 else if (GET_MODE (x) == VOIDmode)
1337 /* Otherwise, check if we can make a valid insn from it. First initialize
1338 our test insn if we haven't already. */
1342 = make_insn_raw (gen_rtx_SET (VOIDmode,
1343 gen_rtx_REG (word_mode,
1344 FIRST_PSEUDO_REGISTER * 2),
1346 NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0;
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 validate_replace_src_group (from, to, insn);
3976 if (num_changes_pending () && apply_change_group ())
3979 if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
3981 /* If above failed and this is a single set, try to simplify the source of
3982 the set given our substitution. We could perhaps try this for multiple
3983 SETs, but it probably won't buy us anything. */
3984 src = simplify_replace_rtx (SET_SRC (set), from, to);
3986 if (!rtx_equal_p (src, SET_SRC (set))
3987 && validate_change (insn, &SET_SRC (set), src, 0))
3990 /* If we've failed to do replacement, have a single SET, and don't already
3991 have a note, add a REG_EQUAL note to not lose information. */
3992 if (!success && note == 0 && set != 0)
3993 note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
3996 /* If there is already a NOTE, update the expression in it with our
3999 XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to);
4001 /* REG_EQUAL may get simplified into register.
4002 We don't allow that. Remove that note. This code ought
4003 not to hapen, because previous code ought to syntetize
4004 reg-reg move, but be on the safe side. */
4005 if (note && REG_P (XEXP (note, 0)))
4006 remove_note (insn, note);
4011 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
4012 NULL no such set is found. */
4014 static struct expr *
4015 find_avail_set (regno, insn)
4019 /* SET1 contains the last set found that can be returned to the caller for
4020 use in a substitution. */
4021 struct expr *set1 = 0;
4023 /* Loops are not possible here. To get a loop we would need two sets
4024 available at the start of the block containing INSN. ie we would
4025 need two sets like this available at the start of the block:
4027 (set (reg X) (reg Y))
4028 (set (reg Y) (reg X))
4030 This can not happen since the set of (reg Y) would have killed the
4031 set of (reg X) making it unavailable at the start of this block. */
4035 struct expr *set = lookup_set (regno, NULL_RTX);
4037 /* Find a set that is available at the start of the block
4038 which contains INSN. */
4041 if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
4043 set = next_set (regno, set);
4046 /* If no available set was found we've reached the end of the
4047 (possibly empty) copy chain. */
4051 if (GET_CODE (set->expr) != SET)
4054 src = SET_SRC (set->expr);
4056 /* We know the set is available.
4057 Now check that SRC is ANTLOC (i.e. none of the source operands
4058 have changed since the start of the block).
4060 If the source operand changed, we may still use it for the next
4061 iteration of this loop, but we may not use it for substitutions. */
4063 if (CONSTANT_P (src) || oprs_not_set_p (src, insn))
4066 /* If the source of the set is anything except a register, then
4067 we have reached the end of the copy chain. */
4068 if (GET_CODE (src) != REG)
4071 /* Follow the copy chain, ie start another iteration of the loop
4072 and see if we have an available copy into SRC. */
4073 regno = REGNO (src);
4076 /* SET1 holds the last set that was available and anticipatable at
4081 /* Subroutine of cprop_insn that tries to propagate constants into
4082 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
4083 it is the instruction that immediately preceeds JUMP, and must be a
4084 single SET of a register. FROM is what we will try to replace,
4085 SRC is the constant we will try to substitute for it. Returns nonzero
4086 if a change was made. */
4089 cprop_jump (bb, setcc, jump, from, src)
4097 rtx set = pc_set (jump);
4099 /* First substitute in the INSN condition as the SET_SRC of the JUMP,
4100 then substitute that given values in this expanded JUMP. */
4103 rtx setcc_set = single_set (setcc);
4104 new_set = simplify_replace_rtx (SET_SRC (set),
4105 SET_DEST (setcc_set),
4106 SET_SRC (setcc_set));
4111 new = simplify_replace_rtx (new_set, from, src);
4113 /* If no simplification can be made, then try the next
4115 if (rtx_equal_p (new, new_set))
4118 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
4123 if (! validate_change (jump, &SET_SRC (set), new, 0))
4126 /* If this has turned into an unconditional jump,
4127 then put a barrier after it so that the unreachable
4128 code will be deleted. */
4129 if (GET_CODE (SET_SRC (set)) == LABEL_REF)
4130 emit_barrier_after (jump);
4134 /* Delete the cc0 setter. */
4135 if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
4136 delete_insn (setcc);
4139 run_jump_opt_after_gcse = 1;
4142 if (gcse_file != NULL)
4145 "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
4146 REGNO (from), INSN_UID (jump));
4147 print_rtl (gcse_file, src);
4148 fprintf (gcse_file, "\n");
4150 purge_dead_edges (bb);
4156 constprop_register (insn, from, to, alter_jumps)
4164 /* Check for reg or cc0 setting instructions followed by
4165 conditional branch instructions first. */
4167 && (sset = single_set (insn)) != NULL
4168 && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
4170 rtx dest = SET_DEST (sset);
4171 if ((REG_P (dest) || CC0_P (dest))
4172 && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to))
4176 /* Handle normal insns next. */
4177 if (GET_CODE (insn) == INSN
4178 && try_replace_reg (from, to, insn))
4181 /* Try to propagate a CONST_INT into a conditional jump.
4182 We're pretty specific about what we will handle in this
4183 code, we can extend this as necessary over time.
4185 Right now the insn in question must look like
4186 (set (pc) (if_then_else ...)) */
4187 else if (alter_jumps && any_condjump_p (insn) && onlyjump_p (insn))
4188 return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to);
4192 /* Perform constant and copy propagation on INSN.
4193 The result is non-zero if a change was made. */
4196 cprop_insn (insn, alter_jumps)
4200 struct reg_use *reg_used;
4208 note_uses (&PATTERN (insn), find_used_regs, NULL);
4210 note = find_reg_equal_equiv_note (insn);
4212 /* We may win even when propagating constants into notes. */
4214 find_used_regs (&XEXP (note, 0), NULL);
4216 for (reg_used = ®_use_table[0]; reg_use_count > 0;
4217 reg_used++, reg_use_count--)
4219 unsigned int regno = REGNO (reg_used->reg_rtx);
4223 /* Ignore registers created by GCSE.
4224 We do this because ... */
4225 if (regno >= max_gcse_regno)
4228 /* If the register has already been set in this block, there's
4229 nothing we can do. */
4230 if (! oprs_not_set_p (reg_used->reg_rtx, insn))
4233 /* Find an assignment that sets reg_used and is available
4234 at the start of the block. */
4235 set = find_avail_set (regno, insn);
4240 /* ??? We might be able to handle PARALLELs. Later. */
4241 if (GET_CODE (pat) != SET)
4244 src = SET_SRC (pat);
4246 /* Constant propagation. */
4247 if (CONSTANT_P (src))
4249 if (constprop_register (insn, reg_used->reg_rtx, src, alter_jumps))
4253 if (gcse_file != NULL)
4255 fprintf (gcse_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
4256 fprintf (gcse_file, "insn %d with constant ", INSN_UID (insn));
4257 print_rtl (gcse_file, src);
4258 fprintf (gcse_file, "\n");
4262 else if (GET_CODE (src) == REG
4263 && REGNO (src) >= FIRST_PSEUDO_REGISTER
4264 && REGNO (src) != regno)
4266 if (try_replace_reg (reg_used->reg_rtx, src, insn))
4270 if (gcse_file != NULL)
4272 fprintf (gcse_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
4273 regno, INSN_UID (insn));
4274 fprintf (gcse_file, " with reg %d\n", REGNO (src));
4277 /* The original insn setting reg_used may or may not now be
4278 deletable. We leave the deletion to flow. */
4279 /* FIXME: If it turns out that the insn isn't deletable,
4280 then we may have unnecessarily extended register lifetimes
4281 and made things worse. */
4290 do_local_cprop (x, insn, alter_jumps)
4295 rtx newreg = NULL, newcnst = NULL;
4297 /* Rule out USE instructions and ASM statements as we don't want to change the hard
4298 registers mentioned. */
4299 if (GET_CODE (x) == REG
4300 && (REGNO (x) >= FIRST_PSEUDO_REGISTER
4301 || (GET_CODE (PATTERN (insn)) != USE && asm_noperands (PATTERN (insn)) < 0)))
4303 cselib_val *val = cselib_lookup (x, GET_MODE (x), 0);
4304 struct elt_loc_list *l;
4308 for (l = val->locs; l; l = l->next)
4310 rtx this_rtx = l->loc;
4313 if (CONSTANT_P (this_rtx))
4315 if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
4316 /* Don't copy propagate if it has attached REG_EQUIV note.
4317 At this point this only function parameters should have
4318 REG_EQUIV notes and if the argument slot is used somewhere
4319 explicitly, it means address of parameter has been taken,
4320 so we should not extend the lifetime of the pseudo. */
4321 && (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX))
4322 || GET_CODE (XEXP (note, 0)) != MEM))
4325 if (newcnst && constprop_register (insn, x, newcnst, alter_jumps))
4327 if (gcse_file != NULL)
4329 fprintf (gcse_file, "LOCAL CONST-PROP: Replacing reg %d in ",
4331 fprintf (gcse_file, "insn %d with constant ",
4333 print_rtl (gcse_file, newcnst);
4334 fprintf (gcse_file, "\n");
4339 else if (newreg && newreg != x && try_replace_reg (x, newreg, insn))
4341 if (gcse_file != NULL)
4344 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
4345 REGNO (x), INSN_UID (insn));
4346 fprintf (gcse_file, " with reg %d\n", REGNO (newreg));
4356 local_cprop_pass (alter_jumps)
4360 struct reg_use *reg_used;
4363 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4367 rtx note = find_reg_equal_equiv_note (insn);
4372 note_uses (&PATTERN (insn), find_used_regs, NULL);
4374 find_used_regs (&XEXP (note, 0), NULL);
4376 for (reg_used = ®_use_table[0]; reg_use_count > 0;
4377 reg_used++, reg_use_count--)
4378 if (do_local_cprop (reg_used->reg_rtx, insn, alter_jumps))
4381 while (reg_use_count);
4383 cselib_process_insn (insn);
4388 /* Forward propagate copies. This includes copies and constants. Return
4389 non-zero if a change was made. */
4399 /* Note we start at block 1. */
4400 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
4402 if (gcse_file != NULL)
4403 fprintf (gcse_file, "\n");
4408 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
4410 /* Reset tables used to keep track of what's still valid [since the
4411 start of the block]. */
4412 reset_opr_set_tables ();
4414 for (insn = bb->head;
4415 insn != NULL && insn != NEXT_INSN (bb->end);
4416 insn = NEXT_INSN (insn))
4419 changed |= cprop_insn (insn, alter_jumps);
4421 /* Keep track of everything modified by this insn. */
4422 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
4423 call mark_oprs_set if we turned the insn into a NOTE. */
4424 if (GET_CODE (insn) != NOTE)
4425 mark_oprs_set (insn);
4429 if (gcse_file != NULL)
4430 fprintf (gcse_file, "\n");
4435 /* Perform one copy/constant propagation pass.
4436 F is the first insn in the function.
4437 PASS is the pass count. */
4440 one_cprop_pass (pass, alter_jumps)
4446 const_prop_count = 0;
4447 copy_prop_count = 0;
4449 local_cprop_pass (alter_jumps);
4451 alloc_set_hash_table (max_cuid);
4452 compute_set_hash_table ();
4454 dump_hash_table (gcse_file, "SET", set_hash_table, set_hash_table_size,
4458 alloc_cprop_mem (last_basic_block, n_sets);
4459 compute_cprop_data ();
4460 changed = cprop (alter_jumps);
4462 changed |= bypass_conditional_jumps ();
4466 free_set_hash_table ();
4470 fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, ",
4471 current_function_name, pass, bytes_used);
4472 fprintf (gcse_file, "%d const props, %d copy props\n\n",
4473 const_prop_count, copy_prop_count);
4479 /* Bypass conditional jumps. */
4481 /* Find a set of REGNO to a constant that is available at the end of basic
4482 block BB. Returns NULL if no such set is found. Based heavily upon
4485 static struct expr *
4486 find_bypass_set (regno, bb)
4490 struct expr *result = 0;
4495 struct expr *set = lookup_set (regno, NULL_RTX);
4499 if (TEST_BIT (cprop_avout[bb], set->bitmap_index))
4501 set = next_set (regno, set);
4507 if (GET_CODE (set->expr) != SET)
4510 src = SET_SRC (set->expr);
4511 if (CONSTANT_P (src))
4514 if (GET_CODE (src) != REG)
4517 regno = REGNO (src);
4523 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
4524 basic block BB which has more than one predecessor. If not NULL, SETCC
4525 is the first instruction of BB, which is immediately followed by JUMP_INSN
4526 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
4527 Returns nonzero if a change was made. */
4530 bypass_block (bb, setcc, jump)
4538 insn = (setcc != NULL) ? setcc : jump;
4540 /* Determine set of register uses in INSN. */
4542 note_uses (&PATTERN (insn), find_used_regs, NULL);
4543 note = find_reg_equal_equiv_note (insn);
4545 find_used_regs (&XEXP (note, 0), NULL);
4548 for (e = bb->pred; e; e = enext)
4550 enext = e->pred_next;
4551 for (i = 0; i < reg_use_count; i++)
4553 struct reg_use *reg_used = ®_use_table[i];
4554 unsigned int regno = REGNO (reg_used->reg_rtx);
4555 basic_block dest, old_dest;
4559 if (regno >= max_gcse_regno)
4562 set = find_bypass_set (regno, e->src->index);
4567 src = SET_SRC (pc_set (jump));
4570 src = simplify_replace_rtx (src,
4571 SET_DEST (PATTERN (setcc)),
4572 SET_SRC (PATTERN (setcc)));
4574 new = simplify_replace_rtx (src, reg_used->reg_rtx,
4575 SET_SRC (set->expr));
4578 dest = FALLTHRU_EDGE (bb)->dest;
4579 else if (GET_CODE (new) == LABEL_REF)
4580 dest = BRANCH_EDGE (bb)->dest;
4584 /* Once basic block indices are stable, we should be able
4585 to use redirect_edge_and_branch_force instead. */
4587 if (dest != NULL && dest != old_dest
4588 && redirect_edge_and_branch (e, dest))
4590 /* Copy the register setter to the redirected edge.
4591 Don't copy CC0 setters, as CC0 is dead after jump. */
4594 rtx pat = PATTERN (setcc);
4595 if (!CC0_P (SET_DEST (pat)))
4596 insert_insn_on_edge (copy_insn (pat), e);
4599 if (gcse_file != NULL)
4601 fprintf (gcse_file, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
4602 regno, INSN_UID (jump));
4603 print_rtl (gcse_file, SET_SRC (set->expr));
4604 fprintf (gcse_file, "\nBypass edge from %d->%d to %d\n",
4605 e->src->index, old_dest->index, dest->index);
4615 /* Find basic blocks with more than one predecessor that only contain a
4616 single conditional jump. If the result of the comparison is known at
4617 compile-time from any incoming edge, redirect that edge to the
4618 appropriate target. Returns nonzero if a change was made. */
4621 bypass_conditional_jumps ()
4629 /* Note we start at block 1. */
4630 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
4634 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb,
4635 EXIT_BLOCK_PTR, next_bb)
4637 /* Check for more than one predecessor. */
4638 if (bb->pred && bb->pred->pred_next)
4641 for (insn = bb->head;
4642 insn != NULL && insn != NEXT_INSN (bb->end);
4643 insn = NEXT_INSN (insn))
4644 if (GET_CODE (insn) == INSN)
4648 if (GET_CODE (PATTERN (insn)) != SET)
4651 dest = SET_DEST (PATTERN (insn));
4652 if (REG_P (dest) || CC0_P (dest))
4657 else if (GET_CODE (insn) == JUMP_INSN)
4659 if (any_condjump_p (insn) && onlyjump_p (insn))
4660 changed |= bypass_block (bb, setcc, insn);
4663 else if (INSN_P (insn))
4668 /* If we bypassed any register setting insns, we inserted a
4669 copy on the redirected edge. These need to be commited. */
4671 commit_edge_insertions();
4676 /* Compute PRE+LCM working variables. */
4678 /* Local properties of expressions. */
4679 /* Nonzero for expressions that are transparent in the block. */
4680 static sbitmap *transp;
4682 /* Nonzero for expressions that are transparent at the end of the block.
4683 This is only zero for expressions killed by abnormal critical edge
4684 created by a calls. */
4685 static sbitmap *transpout;
4687 /* Nonzero for expressions that are computed (available) in the block. */
4688 static sbitmap *comp;
4690 /* Nonzero for expressions that are locally anticipatable in the block. */
4691 static sbitmap *antloc;
4693 /* Nonzero for expressions where this block is an optimal computation
4695 static sbitmap *pre_optimal;
4697 /* Nonzero for expressions which are redundant in a particular block. */
4698 static sbitmap *pre_redundant;
4700 /* Nonzero for expressions which should be inserted on a specific edge. */
4701 static sbitmap *pre_insert_map;
4703 /* Nonzero for expressions which should be deleted in a specific block. */
4704 static sbitmap *pre_delete_map;
4706 /* Contains the edge_list returned by pre_edge_lcm. */
4707 static struct edge_list *edge_list;
4709 /* Redundant insns. */
4710 static sbitmap pre_redundant_insns;
4712 /* Allocate vars used for PRE analysis. */
4715 alloc_pre_mem (n_blocks, n_exprs)
4716 int n_blocks, n_exprs;
4718 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
4719 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
4720 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
4723 pre_redundant = NULL;
4724 pre_insert_map = NULL;
4725 pre_delete_map = NULL;
4728 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
4730 /* pre_insert and pre_delete are allocated later. */
4733 /* Free vars used for PRE analysis. */
4738 sbitmap_vector_free (transp);
4739 sbitmap_vector_free (comp);
4741 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
4744 sbitmap_vector_free (pre_optimal);
4746 sbitmap_vector_free (pre_redundant);
4748 sbitmap_vector_free (pre_insert_map);
4750 sbitmap_vector_free (pre_delete_map);
4752 sbitmap_vector_free (ae_in);
4754 sbitmap_vector_free (ae_out);
4756 transp = comp = NULL;
4757 pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
4758 ae_in = ae_out = NULL;
4761 /* Top level routine to do the dataflow analysis needed by PRE. */
4766 sbitmap trapping_expr;
4770 compute_local_properties (transp, comp, antloc, 0);
4771 sbitmap_vector_zero (ae_kill, last_basic_block);
4773 /* Collect expressions which might trap. */
4774 trapping_expr = sbitmap_alloc (n_exprs);
4775 sbitmap_zero (trapping_expr);
4776 for (ui = 0; ui < expr_hash_table_size; ui++)
4779 for (e = expr_hash_table[ui]; e != NULL; e = e->next_same_hash)
4780 if (may_trap_p (e->expr))
4781 SET_BIT (trapping_expr, e->bitmap_index);
4784 /* Compute ae_kill for each basic block using:
4788 This is significantly faster than compute_ae_kill. */
4794 /* If the current block is the destination of an abnormal edge, we
4795 kill all trapping expressions because we won't be able to properly
4796 place the instruction on the edge. So make them neither
4797 anticipatable nor transparent. This is fairly conservative. */
4798 for (e = bb->pred; e ; e = e->pred_next)
4799 if (e->flags & EDGE_ABNORMAL)
4801 sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr);
4802 sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr);
4806 sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]);
4807 sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]);
4810 edge_list = pre_edge_lcm (gcse_file, n_exprs, transp, comp, antloc,
4811 ae_kill, &pre_insert_map, &pre_delete_map);
4812 sbitmap_vector_free (antloc);
4814 sbitmap_vector_free (ae_kill);
4816 sbitmap_free (trapping_expr);
4821 /* Return non-zero if an occurrence of expression EXPR in OCCR_BB would reach
4824 VISITED is a pointer to a working buffer for tracking which BB's have
4825 been visited. It is NULL for the top-level call.
4827 We treat reaching expressions that go through blocks containing the same
4828 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
4829 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
4830 2 as not reaching. The intent is to improve the probability of finding
4831 only one reaching expression and to reduce register lifetimes by picking
4832 the closest such expression. */
4835 pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited)
4836 basic_block occr_bb;
4843 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
4845 basic_block pred_bb = pred->src;
4847 if (pred->src == ENTRY_BLOCK_PTR
4848 /* Has predecessor has already been visited? */
4849 || visited[pred_bb->index])
4850 ;/* Nothing to do. */
4852 /* Does this predecessor generate this expression? */
4853 else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
4855 /* Is this the occurrence we're looking for?
4856 Note that there's only one generating occurrence per block
4857 so we just need to check the block number. */
4858 if (occr_bb == pred_bb)
4861 visited[pred_bb->index] = 1;
4863 /* Ignore this predecessor if it kills the expression. */
4864 else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
4865 visited[pred_bb->index] = 1;
4867 /* Neither gen nor kill. */
4870 visited[pred_bb->index] = 1;
4871 if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
4876 /* All paths have been checked. */
4880 /* The wrapper for pre_expr_reaches_here_work that ensures that any
4881 memory allocated for that function is returned. */
4884 pre_expr_reaches_here_p (occr_bb, expr, bb)
4885 basic_block occr_bb;
4890 char *visited = (char *) xcalloc (last_basic_block, 1);
4892 rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited);
4899 /* Given an expr, generate RTL which we can insert at the end of a BB,
4900 or on an edge. Set the block number of any insns generated to
4904 process_insert_insn (expr)
4907 rtx reg = expr->reaching_reg;
4908 rtx exp = copy_rtx (expr->expr);
4913 /* If the expression is something that's an operand, like a constant,
4914 just copy it to a register. */
4915 if (general_operand (exp, GET_MODE (reg)))
4916 emit_move_insn (reg, exp);
4918 /* Otherwise, make a new insn to compute this expression and make sure the
4919 insn will be recognized (this also adds any needed CLOBBERs). Copy the
4920 expression to make sure we don't have any sharing issues. */
4921 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode, reg, exp))))
4930 /* Add EXPR to the end of basic block BB.
4932 This is used by both the PRE and code hoisting.
4934 For PRE, we want to verify that the expr is either transparent
4935 or locally anticipatable in the target block. This check makes
4936 no sense for code hoisting. */
4939 insert_insn_end_bb (expr, bb, pre)
4946 rtx reg = expr->reaching_reg;
4947 int regno = REGNO (reg);
4950 pat = process_insert_insn (expr);
4951 if (pat == NULL_RTX || ! INSN_P (pat))
4955 while (NEXT_INSN (pat_end) != NULL_RTX)
4956 pat_end = NEXT_INSN (pat_end);
4958 /* If the last insn is a jump, insert EXPR in front [taking care to
4959 handle cc0, etc. properly]. Similary we need to care trapping
4960 instructions in presence of non-call exceptions. */
4962 if (GET_CODE (insn) == JUMP_INSN
4963 || (GET_CODE (insn) == INSN
4964 && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL))))
4969 /* It should always be the case that we can put these instructions
4970 anywhere in the basic block with performing PRE optimizations.
4972 if (GET_CODE (insn) == INSN && pre
4973 && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
4974 && !TEST_BIT (transp[bb->index], expr->bitmap_index))
4977 /* If this is a jump table, then we can't insert stuff here. Since
4978 we know the previous real insn must be the tablejump, we insert
4979 the new instruction just before the tablejump. */
4980 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
4981 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
4982 insn = prev_real_insn (insn);
4985 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4986 if cc0 isn't set. */
4987 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
4989 insn = XEXP (note, 0);
4992 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
4993 if (maybe_cc0_setter
4994 && INSN_P (maybe_cc0_setter)
4995 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
4996 insn = maybe_cc0_setter;
4999 /* FIXME: What if something in cc0/jump uses value set in new insn? */
5000 new_insn = emit_insn_before (pat, insn);
5003 /* Likewise if the last insn is a call, as will happen in the presence
5004 of exception handling. */
5005 else if (GET_CODE (insn) == CALL_INSN
5006 && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL)))
5008 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
5009 we search backward and place the instructions before the first
5010 parameter is loaded. Do this for everyone for consistency and a
5011 presumtion that we'll get better code elsewhere as well.
5013 It should always be the case that we can put these instructions
5014 anywhere in the basic block with performing PRE optimizations.
5018 && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
5019 && !TEST_BIT (transp[bb->index], expr->bitmap_index))
5022 /* Since different machines initialize their parameter registers
5023 in different orders, assume nothing. Collect the set of all
5024 parameter registers. */
5025 insn = find_first_parameter_load (insn, bb->head);
5027 /* If we found all the parameter loads, then we want to insert
5028 before the first parameter load.
5030 If we did not find all the parameter loads, then we might have
5031 stopped on the head of the block, which could be a CODE_LABEL.
5032 If we inserted before the CODE_LABEL, then we would be putting
5033 the insn in the wrong basic block. In that case, put the insn
5034 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
5035 while (GET_CODE (insn) == CODE_LABEL
5036 || NOTE_INSN_BASIC_BLOCK_P (insn))
5037 insn = NEXT_INSN (insn);
5039 new_insn = emit_insn_before (pat, insn);
5042 new_insn = emit_insn_after (pat, insn);
5048 add_label_notes (PATTERN (pat), new_insn);
5049 note_stores (PATTERN (pat), record_set_info, pat);
5053 pat = NEXT_INSN (pat);
5056 gcse_create_count++;
5060 fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, ",
5061 bb->index, INSN_UID (new_insn));
5062 fprintf (gcse_file, "copying expression %d to reg %d\n",
5063 expr->bitmap_index, regno);
5067 /* Insert partially redundant expressions on edges in the CFG to make
5068 the expressions fully redundant. */
5071 pre_edge_insert (edge_list, index_map)
5072 struct edge_list *edge_list;
5073 struct expr **index_map;
5075 int e, i, j, num_edges, set_size, did_insert = 0;
5078 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
5079 if it reaches any of the deleted expressions. */
5081 set_size = pre_insert_map[0]->size;
5082 num_edges = NUM_EDGES (edge_list);
5083 inserted = sbitmap_vector_alloc (num_edges, n_exprs);
5084 sbitmap_vector_zero (inserted, num_edges);
5086 for (e = 0; e < num_edges; e++)
5089 basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
5091 for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
5093 SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
5095 for (j = indx; insert && j < n_exprs; j++, insert >>= 1)
5096 if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
5098 struct expr *expr = index_map[j];
5101 /* Now look at each deleted occurrence of this expression. */
5102 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5104 if (! occr->deleted_p)
5107 /* Insert this expression on this edge if if it would
5108 reach the deleted occurrence in BB. */
5109 if (!TEST_BIT (inserted[e], j))
5112 edge eg = INDEX_EDGE (edge_list, e);
5114 /* We can't insert anything on an abnormal and
5115 critical edge, so we insert the insn at the end of
5116 the previous block. There are several alternatives
5117 detailed in Morgans book P277 (sec 10.5) for
5118 handling this situation. This one is easiest for
5121 if ((eg->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
5122 insert_insn_end_bb (index_map[j], bb, 0);
5125 insn = process_insert_insn (index_map[j]);
5126 insert_insn_on_edge (insn, eg);
5131 fprintf (gcse_file, "PRE/HOIST: edge (%d,%d), ",
5133 INDEX_EDGE_SUCC_BB (edge_list, e)->index);
5134 fprintf (gcse_file, "copy expression %d\n",
5135 expr->bitmap_index);
5138 update_ld_motion_stores (expr);
5139 SET_BIT (inserted[e], j);
5141 gcse_create_count++;
5148 sbitmap_vector_free (inserted);
5152 /* Copy the result of INSN to REG. INDX is the expression number. */
5155 pre_insert_copy_insn (expr, insn)
5159 rtx reg = expr->reaching_reg;
5160 int regno = REGNO (reg);
5161 int indx = expr->bitmap_index;
5162 rtx set = single_set (insn);
5168 new_insn = emit_insn_after (gen_move_insn (reg, SET_DEST (set)), insn);
5170 /* Keep register set table up to date. */
5171 record_one_set (regno, new_insn);
5173 gcse_create_count++;
5177 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
5178 BLOCK_NUM (insn), INSN_UID (new_insn), indx,
5179 INSN_UID (insn), regno);
5180 update_ld_motion_stores (expr);
5183 /* Copy available expressions that reach the redundant expression
5184 to `reaching_reg'. */
5187 pre_insert_copies ()
5194 /* For each available expression in the table, copy the result to
5195 `reaching_reg' if the expression reaches a deleted one.
5197 ??? The current algorithm is rather brute force.
5198 Need to do some profiling. */
5200 for (i = 0; i < expr_hash_table_size; i++)
5201 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
5203 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
5204 we don't want to insert a copy here because the expression may not
5205 really be redundant. So only insert an insn if the expression was
5206 deleted. This test also avoids further processing if the
5207 expression wasn't deleted anywhere. */
5208 if (expr->reaching_reg == NULL)
5211 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5213 if (! occr->deleted_p)
5216 for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
5218 rtx insn = avail->insn;
5220 /* No need to handle this one if handled already. */
5221 if (avail->copied_p)
5224 /* Don't handle this one if it's a redundant one. */
5225 if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
5228 /* Or if the expression doesn't reach the deleted one. */
5229 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
5231 BLOCK_FOR_INSN (occr->insn)))
5234 /* Copy the result of avail to reaching_reg. */
5235 pre_insert_copy_insn (expr, insn);
5236 avail->copied_p = 1;
5242 /* Emit move from SRC to DEST noting the equivalence with expression computed
5245 gcse_emit_move_after (src, dest, insn)
5246 rtx src, dest, insn;
5249 rtx set = single_set (insn), set2;
5253 /* This should never fail since we're creating a reg->reg copy
5254 we've verified to be valid. */
5256 new = emit_insn_after (gen_move_insn (dest, src), insn);
5258 /* Note the equivalence for local CSE pass. */
5259 set2 = single_set (new);
5260 if (!set2 || !rtx_equal_p (SET_DEST (set2), dest))
5262 if ((note = find_reg_equal_equiv_note (insn)))
5263 eqv = XEXP (note, 0);
5265 eqv = SET_SRC (set);
5267 set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (src));
5272 /* Delete redundant computations.
5273 Deletion is done by changing the insn to copy the `reaching_reg' of
5274 the expression into the result of the SET. It is left to later passes
5275 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
5277 Returns non-zero if a change is made. */
5288 for (i = 0; i < expr_hash_table_size; i++)
5289 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
5291 int indx = expr->bitmap_index;
5293 /* We only need to search antic_occr since we require
5296 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5298 rtx insn = occr->insn;
5300 basic_block bb = BLOCK_FOR_INSN (insn);
5302 if (TEST_BIT (pre_delete_map[bb->index], indx))
5304 set = single_set (insn);
5308 /* Create a pseudo-reg to store the result of reaching
5309 expressions into. Get the mode for the new pseudo from
5310 the mode of the original destination pseudo. */
5311 if (expr->reaching_reg == NULL)
5313 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
5315 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
5317 occr->deleted_p = 1;
5318 SET_BIT (pre_redundant_insns, INSN_CUID (insn));
5325 "PRE: redundant insn %d (expression %d) in ",
5326 INSN_UID (insn), indx);
5327 fprintf (gcse_file, "bb %d, reaching reg is %d\n",
5328 bb->index, REGNO (expr->reaching_reg));
5337 /* Perform GCSE optimizations using PRE.
5338 This is called by one_pre_gcse_pass after all the dataflow analysis
5341 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
5342 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
5343 Compiler Design and Implementation.
5345 ??? A new pseudo reg is created to hold the reaching expression. The nice
5346 thing about the classical approach is that it would try to use an existing
5347 reg. If the register can't be adequately optimized [i.e. we introduce
5348 reload problems], one could add a pass here to propagate the new register
5351 ??? We don't handle single sets in PARALLELs because we're [currently] not
5352 able to copy the rest of the parallel when we insert copies to create full
5353 redundancies from partial redundancies. However, there's no reason why we
5354 can't handle PARALLELs in the cases where there are no partial
5361 int did_insert, changed;
5362 struct expr **index_map;
5365 /* Compute a mapping from expression number (`bitmap_index') to
5366 hash table entry. */
5368 index_map = (struct expr **) xcalloc (n_exprs, sizeof (struct expr *));
5369 for (i = 0; i < expr_hash_table_size; i++)
5370 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
5371 index_map[expr->bitmap_index] = expr;
5373 /* Reset bitmap used to track which insns are redundant. */
5374 pre_redundant_insns = sbitmap_alloc (max_cuid);
5375 sbitmap_zero (pre_redundant_insns);
5377 /* Delete the redundant insns first so that
5378 - we know what register to use for the new insns and for the other
5379 ones with reaching expressions
5380 - we know which insns are redundant when we go to create copies */
5382 changed = pre_delete ();
5384 did_insert = pre_edge_insert (edge_list, index_map);
5386 /* In other places with reaching expressions, copy the expression to the
5387 specially allocated pseudo-reg that reaches the redundant expr. */
5388 pre_insert_copies ();
5391 commit_edge_insertions ();
5396 sbitmap_free (pre_redundant_insns);
5400 /* Top level routine to perform one PRE GCSE pass.
5402 Return non-zero if a change was made. */
5405 one_pre_gcse_pass (pass)
5410 gcse_subst_count = 0;
5411 gcse_create_count = 0;
5413 alloc_expr_hash_table (max_cuid);
5414 add_noreturn_fake_exit_edges ();
5416 compute_ld_motion_mems ();
5418 compute_expr_hash_table ();
5419 trim_ld_motion_mems ();
5421 dump_hash_table (gcse_file, "Expression", expr_hash_table,
5422 expr_hash_table_size, n_exprs);
5426 alloc_pre_mem (last_basic_block, n_exprs);
5427 compute_pre_data ();
5428 changed |= pre_gcse ();
5429 free_edge_list (edge_list);
5434 remove_fake_edges ();
5435 free_expr_hash_table ();
5439 fprintf (gcse_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
5440 current_function_name, pass, bytes_used);
5441 fprintf (gcse_file, "%d substs, %d insns created\n",
5442 gcse_subst_count, gcse_create_count);
5448 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
5449 If notes are added to an insn which references a CODE_LABEL, the
5450 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
5451 because the following loop optimization pass requires them. */
5453 /* ??? This is very similar to the loop.c add_label_notes function. We
5454 could probably share code here. */
5456 /* ??? If there was a jump optimization pass after gcse and before loop,
5457 then we would not need to do this here, because jump would add the
5458 necessary REG_LABEL notes. */
5461 add_label_notes (x, insn)
5465 enum rtx_code code = GET_CODE (x);
5469 if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
5471 /* This code used to ignore labels that referred to dispatch tables to
5472 avoid flow generating (slighly) worse code.
5474 We no longer ignore such label references (see LABEL_REF handling in
5475 mark_jump_label for additional information). */
5477 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0),
5479 if (LABEL_P (XEXP (x, 0)))
5480 LABEL_NUSES (XEXP (x, 0))++;
5484 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
5487 add_label_notes (XEXP (x, i), insn);
5488 else if (fmt[i] == 'E')
5489 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5490 add_label_notes (XVECEXP (x, i, j), insn);
5494 /* Compute transparent outgoing information for each block.
5496 An expression is transparent to an edge unless it is killed by
5497 the edge itself. This can only happen with abnormal control flow,
5498 when the edge is traversed through a call. This happens with
5499 non-local labels and exceptions.
5501 This would not be necessary if we split the edge. While this is
5502 normally impossible for abnormal critical edges, with some effort
5503 it should be possible with exception handling, since we still have
5504 control over which handler should be invoked. But due to increased
5505 EH table sizes, this may not be worthwhile. */
5508 compute_transpout ()
5514 sbitmap_vector_ones (transpout, last_basic_block);
5518 /* Note that flow inserted a nop a the end of basic blocks that
5519 end in call instructions for reasons other than abnormal
5521 if (GET_CODE (bb->end) != CALL_INSN)
5524 for (i = 0; i < expr_hash_table_size; i++)
5525 for (expr = expr_hash_table[i]; expr ; expr = expr->next_same_hash)
5526 if (GET_CODE (expr->expr) == MEM)
5528 if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
5529 && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
5532 /* ??? Optimally, we would use interprocedural alias
5533 analysis to determine if this mem is actually killed
5535 RESET_BIT (transpout[bb->index], expr->bitmap_index);
5540 /* Removal of useless null pointer checks */
5542 /* Called via note_stores. X is set by SETTER. If X is a register we must
5543 invalidate nonnull_local and set nonnull_killed. DATA is really a
5544 `null_pointer_info *'.
5546 We ignore hard registers. */
5549 invalidate_nonnull_info (x, setter, data)
5551 rtx setter ATTRIBUTE_UNUSED;
5555 struct null_pointer_info *npi = (struct null_pointer_info *) data;
5557 while (GET_CODE (x) == SUBREG)
5560 /* Ignore anything that is not a register or is a hard register. */
5561 if (GET_CODE (x) != REG
5562 || REGNO (x) < npi->min_reg
5563 || REGNO (x) >= npi->max_reg)
5566 regno = REGNO (x) - npi->min_reg;
5568 RESET_BIT (npi->nonnull_local[npi->current_block->index], regno);
5569 SET_BIT (npi->nonnull_killed[npi->current_block->index], regno);
5572 /* Do null-pointer check elimination for the registers indicated in
5573 NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
5574 they are not our responsibility to free. */
5577 delete_null_pointer_checks_1 (block_reg, nonnull_avin,
5579 unsigned int *block_reg;
5580 sbitmap *nonnull_avin;
5581 sbitmap *nonnull_avout;
5582 struct null_pointer_info *npi;
5584 basic_block bb, current_block;
5585 sbitmap *nonnull_local = npi->nonnull_local;
5586 sbitmap *nonnull_killed = npi->nonnull_killed;
5587 int something_changed = 0;
5589 /* Compute local properties, nonnull and killed. A register will have
5590 the nonnull property if at the end of the current block its value is
5591 known to be nonnull. The killed property indicates that somewhere in
5592 the block any information we had about the register is killed.
5594 Note that a register can have both properties in a single block. That
5595 indicates that it's killed, then later in the block a new value is
5597 sbitmap_vector_zero (nonnull_local, last_basic_block);
5598 sbitmap_vector_zero (nonnull_killed, last_basic_block);
5600 FOR_EACH_BB (current_block)
5602 rtx insn, stop_insn;
5604 /* Set the current block for invalidate_nonnull_info. */
5605 npi->current_block = current_block;
5607 /* Scan each insn in the basic block looking for memory references and
5609 stop_insn = NEXT_INSN (current_block->end);
5610 for (insn = current_block->head;
5612 insn = NEXT_INSN (insn))
5617 /* Ignore anything that is not a normal insn. */
5618 if (! INSN_P (insn))
5621 /* Basically ignore anything that is not a simple SET. We do have
5622 to make sure to invalidate nonnull_local and set nonnull_killed
5623 for such insns though. */
5624 set = single_set (insn);
5627 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5631 /* See if we've got a usable memory load. We handle it first
5632 in case it uses its address register as a dest (which kills
5633 the nonnull property). */
5634 if (GET_CODE (SET_SRC (set)) == MEM
5635 && GET_CODE ((reg = XEXP (SET_SRC (set), 0))) == REG
5636 && REGNO (reg) >= npi->min_reg
5637 && REGNO (reg) < npi->max_reg)
5638 SET_BIT (nonnull_local[current_block->index],
5639 REGNO (reg) - npi->min_reg);
5641 /* Now invalidate stuff clobbered by this insn. */
5642 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5644 /* And handle stores, we do these last since any sets in INSN can
5645 not kill the nonnull property if it is derived from a MEM
5646 appearing in a SET_DEST. */
5647 if (GET_CODE (SET_DEST (set)) == MEM
5648 && GET_CODE ((reg = XEXP (SET_DEST (set), 0))) == REG
5649 && REGNO (reg) >= npi->min_reg
5650 && REGNO (reg) < npi->max_reg)
5651 SET_BIT (nonnull_local[current_block->index],
5652 REGNO (reg) - npi->min_reg);
5656 /* Now compute global properties based on the local properties. This
5657 is a classic global availablity algorithm. */
5658 compute_available (nonnull_local, nonnull_killed,
5659 nonnull_avout, nonnull_avin);
5661 /* Now look at each bb and see if it ends with a compare of a value
5665 rtx last_insn = bb->end;
5666 rtx condition, earliest;
5667 int compare_and_branch;
5669 /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
5670 since BLOCK_REG[BB] is zero if this block did not end with a
5671 comparison against zero, this condition works. */
5672 if (block_reg[bb->index] < npi->min_reg
5673 || block_reg[bb->index] >= npi->max_reg)
5676 /* LAST_INSN is a conditional jump. Get its condition. */
5677 condition = get_condition (last_insn, &earliest);
5679 /* If we can't determine the condition then skip. */
5683 /* Is the register known to have a nonzero value? */
5684 if (!TEST_BIT (nonnull_avout[bb->index], block_reg[bb->index] - npi->min_reg))
5687 /* Try to compute whether the compare/branch at the loop end is one or
5688 two instructions. */
5689 if (earliest == last_insn)
5690 compare_and_branch = 1;
5691 else if (earliest == prev_nonnote_insn (last_insn))
5692 compare_and_branch = 2;
5696 /* We know the register in this comparison is nonnull at exit from
5697 this block. We can optimize this comparison. */
5698 if (GET_CODE (condition) == NE)
5702 new_jump = emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn)),
5704 JUMP_LABEL (new_jump) = JUMP_LABEL (last_insn);
5705 LABEL_NUSES (JUMP_LABEL (new_jump))++;
5706 emit_barrier_after (new_jump);
5709 something_changed = 1;
5710 delete_insn (last_insn);
5711 if (compare_and_branch == 2)
5712 delete_insn (earliest);
5713 purge_dead_edges (bb);
5715 /* Don't check this block again. (Note that BLOCK_END is
5716 invalid here; we deleted the last instruction in the
5718 block_reg[bb->index] = 0;
5721 return something_changed;
5724 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
5727 This is conceptually similar to global constant/copy propagation and
5728 classic global CSE (it even uses the same dataflow equations as cprop).
5730 If a register is used as memory address with the form (mem (reg)), then we
5731 know that REG can not be zero at that point in the program. Any instruction
5732 which sets REG "kills" this property.
5734 So, if every path leading to a conditional branch has an available memory
5735 reference of that form, then we know the register can not have the value
5736 zero at the conditional branch.
5738 So we merely need to compute the local properies and propagate that data
5739 around the cfg, then optimize where possible.
5741 We run this pass two times. Once before CSE, then again after CSE. This
5742 has proven to be the most profitable approach. It is rare for new
5743 optimization opportunities of this nature to appear after the first CSE
5746 This could probably be integrated with global cprop with a little work. */
5749 delete_null_pointer_checks (f)
5750 rtx f ATTRIBUTE_UNUSED;
5752 sbitmap *nonnull_avin, *nonnull_avout;
5753 unsigned int *block_reg;
5758 struct null_pointer_info npi;
5759 int something_changed = 0;
5761 /* If we have only a single block, then there's nothing to do. */
5762 if (n_basic_blocks <= 1)
5765 /* Trying to perform global optimizations on flow graphs which have
5766 a high connectivity will take a long time and is unlikely to be
5767 particularly useful.
5769 In normal circumstances a cfg should have about twice as many edges
5770 as blocks. But we do not want to punish small functions which have
5771 a couple switch statements. So we require a relatively large number
5772 of basic blocks and the ratio of edges to blocks to be high. */
5773 if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
5776 /* We need four bitmaps, each with a bit for each register in each
5778 max_reg = max_reg_num ();
5779 regs_per_pass = get_bitmap_width (4, last_basic_block, max_reg);
5781 /* Allocate bitmaps to hold local and global properties. */
5782 npi.nonnull_local = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5783 npi.nonnull_killed = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5784 nonnull_avin = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5785 nonnull_avout = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5787 /* Go through the basic blocks, seeing whether or not each block
5788 ends with a conditional branch whose condition is a comparison
5789 against zero. Record the register compared in BLOCK_REG. */
5790 block_reg = (unsigned int *) xcalloc (last_basic_block, sizeof (int));
5793 rtx last_insn = bb->end;
5794 rtx condition, earliest, reg;
5796 /* We only want conditional branches. */
5797 if (GET_CODE (last_insn) != JUMP_INSN
5798 || !any_condjump_p (last_insn)
5799 || !onlyjump_p (last_insn))
5802 /* LAST_INSN is a conditional jump. Get its condition. */
5803 condition = get_condition (last_insn, &earliest);
5805 /* If we were unable to get the condition, or it is not an equality
5806 comparison against zero then there's nothing we can do. */
5808 || (GET_CODE (condition) != NE && GET_CODE (condition) != EQ)
5809 || GET_CODE (XEXP (condition, 1)) != CONST_INT
5810 || (XEXP (condition, 1)
5811 != CONST0_RTX (GET_MODE (XEXP (condition, 0)))))
5814 /* We must be checking a register against zero. */
5815 reg = XEXP (condition, 0);
5816 if (GET_CODE (reg) != REG)
5819 block_reg[bb->index] = REGNO (reg);
5822 /* Go through the algorithm for each block of registers. */
5823 for (reg = FIRST_PSEUDO_REGISTER; reg < max_reg; reg += regs_per_pass)
5826 npi.max_reg = MIN (reg + regs_per_pass, max_reg);
5827 something_changed |= delete_null_pointer_checks_1 (block_reg,
5833 /* Free the table of registers compared at the end of every block. */
5837 sbitmap_vector_free (npi.nonnull_local);
5838 sbitmap_vector_free (npi.nonnull_killed);
5839 sbitmap_vector_free (nonnull_avin);
5840 sbitmap_vector_free (nonnull_avout);
5842 return something_changed;
5845 /* Code Hoisting variables and subroutines. */
5847 /* Very busy expressions. */
5848 static sbitmap *hoist_vbein;
5849 static sbitmap *hoist_vbeout;
5851 /* Hoistable expressions. */
5852 static sbitmap *hoist_exprs;
5854 /* Dominator bitmaps. */
5855 dominance_info dominators;
5857 /* ??? We could compute post dominators and run this algorithm in
5858 reverse to to perform tail merging, doing so would probably be
5859 more effective than the tail merging code in jump.c.
5861 It's unclear if tail merging could be run in parallel with
5862 code hoisting. It would be nice. */
5864 /* Allocate vars used for code hoisting analysis. */
5867 alloc_code_hoist_mem (n_blocks, n_exprs)
5868 int n_blocks, n_exprs;
5870 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
5871 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
5872 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
5874 hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
5875 hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
5876 hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
5877 transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
5880 /* Free vars used for code hoisting analysis. */
5883 free_code_hoist_mem ()
5885 sbitmap_vector_free (antloc);
5886 sbitmap_vector_free (transp);
5887 sbitmap_vector_free (comp);
5889 sbitmap_vector_free (hoist_vbein);
5890 sbitmap_vector_free (hoist_vbeout);
5891 sbitmap_vector_free (hoist_exprs);
5892 sbitmap_vector_free (transpout);
5894 free_dominance_info (dominators);
5897 /* Compute the very busy expressions at entry/exit from each block.
5899 An expression is very busy if all paths from a given point
5900 compute the expression. */
5903 compute_code_hoist_vbeinout ()
5905 int changed, passes;
5908 sbitmap_vector_zero (hoist_vbeout, last_basic_block);
5909 sbitmap_vector_zero (hoist_vbein, last_basic_block);
5918 /* We scan the blocks in the reverse order to speed up
5920 FOR_EACH_BB_REVERSE (bb)
5922 changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index], antloc[bb->index],
5923 hoist_vbeout[bb->index], transp[bb->index]);
5924 if (bb->next_bb != EXIT_BLOCK_PTR)
5925 sbitmap_intersection_of_succs (hoist_vbeout[bb->index], hoist_vbein, bb->index);
5932 fprintf (gcse_file, "hoisting vbeinout computation: %d passes\n", passes);
5935 /* Top level routine to do the dataflow analysis needed by code hoisting. */
5938 compute_code_hoist_data ()
5940 compute_local_properties (transp, comp, antloc, 0);
5941 compute_transpout ();
5942 compute_code_hoist_vbeinout ();
5943 dominators = calculate_dominance_info (CDI_DOMINATORS);
5945 fprintf (gcse_file, "\n");
5948 /* Determine if the expression identified by EXPR_INDEX would
5949 reach BB unimpared if it was placed at the end of EXPR_BB.
5951 It's unclear exactly what Muchnick meant by "unimpared". It seems
5952 to me that the expression must either be computed or transparent in
5953 *every* block in the path(s) from EXPR_BB to BB. Any other definition
5954 would allow the expression to be hoisted out of loops, even if
5955 the expression wasn't a loop invariant.
5957 Contrast this to reachability for PRE where an expression is
5958 considered reachable if *any* path reaches instead of *all*
5962 hoist_expr_reaches_here_p (expr_bb, expr_index, bb, visited)
5963 basic_block expr_bb;
5969 int visited_allocated_locally = 0;
5972 if (visited == NULL)
5974 visited_allocated_locally = 1;
5975 visited = xcalloc (last_basic_block, 1);
5978 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
5980 basic_block pred_bb = pred->src;
5982 if (pred->src == ENTRY_BLOCK_PTR)
5984 else if (pred_bb == expr_bb)
5986 else if (visited[pred_bb->index])
5989 /* Does this predecessor generate this expression? */
5990 else if (TEST_BIT (comp[pred_bb->index], expr_index))
5992 else if (! TEST_BIT (transp[pred_bb->index], expr_index))
5998 visited[pred_bb->index] = 1;
5999 if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
6004 if (visited_allocated_locally)
6007 return (pred == NULL);
6010 /* Actually perform code hoisting. */
6015 basic_block bb, dominated;
6017 unsigned int domby_len;
6019 struct expr **index_map;
6022 sbitmap_vector_zero (hoist_exprs, last_basic_block);
6024 /* Compute a mapping from expression number (`bitmap_index') to
6025 hash table entry. */
6027 index_map = (struct expr **) xcalloc (n_exprs, sizeof (struct expr *));
6028 for (i = 0; i < expr_hash_table_size; i++)
6029 for (expr = expr_hash_table[i]; expr != NULL; expr = expr->next_same_hash)
6030 index_map[expr->bitmap_index] = expr;
6032 /* Walk over each basic block looking for potentially hoistable
6033 expressions, nothing gets hoisted from the entry block. */
6037 int insn_inserted_p;
6039 domby_len = get_dominated_by (dominators, bb, &domby);
6040 /* Examine each expression that is very busy at the exit of this
6041 block. These are the potentially hoistable expressions. */
6042 for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++)
6046 if (TEST_BIT (hoist_vbeout[bb->index], i)
6047 && TEST_BIT (transpout[bb->index], i))
6049 /* We've found a potentially hoistable expression, now
6050 we look at every block BB dominates to see if it
6051 computes the expression. */
6052 for (j = 0; j < domby_len; j++)
6054 dominated = domby[j];
6055 /* Ignore self dominance. */
6056 if (bb == dominated)
6058 /* We've found a dominated block, now see if it computes
6059 the busy expression and whether or not moving that
6060 expression to the "beginning" of that block is safe. */
6061 if (!TEST_BIT (antloc[dominated->index], i))
6064 /* Note if the expression would reach the dominated block
6065 unimpared if it was placed at the end of BB.
6067 Keep track of how many times this expression is hoistable
6068 from a dominated block into BB. */
6069 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
6073 /* If we found more than one hoistable occurrence of this
6074 expression, then note it in the bitmap of expressions to
6075 hoist. It makes no sense to hoist things which are computed
6076 in only one BB, and doing so tends to pessimize register
6077 allocation. One could increase this value to try harder
6078 to avoid any possible code expansion due to register
6079 allocation issues; however experiments have shown that
6080 the vast majority of hoistable expressions are only movable
6081 from two successors, so raising this threshhold is likely
6082 to nullify any benefit we get from code hoisting. */
6085 SET_BIT (hoist_exprs[bb->index], i);
6090 /* If we found nothing to hoist, then quit now. */
6097 /* Loop over all the hoistable expressions. */
6098 for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++)
6100 /* We want to insert the expression into BB only once, so
6101 note when we've inserted it. */
6102 insn_inserted_p = 0;
6104 /* These tests should be the same as the tests above. */
6105 if (TEST_BIT (hoist_vbeout[bb->index], i))
6107 /* We've found a potentially hoistable expression, now
6108 we look at every block BB dominates to see if it
6109 computes the expression. */
6110 for (j = 0; j < domby_len; j++)
6112 dominated = domby[j];
6113 /* Ignore self dominance. */
6114 if (bb == dominated)
6117 /* We've found a dominated block, now see if it computes
6118 the busy expression and whether or not moving that
6119 expression to the "beginning" of that block is safe. */
6120 if (!TEST_BIT (antloc[dominated->index], i))
6123 /* The expression is computed in the dominated block and
6124 it would be safe to compute it at the start of the
6125 dominated block. Now we have to determine if the
6126 expression would reach the dominated block if it was
6127 placed at the end of BB. */
6128 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
6130 struct expr *expr = index_map[i];
6131 struct occr *occr = expr->antic_occr;
6135 /* Find the right occurrence of this expression. */
6136 while (BLOCK_FOR_INSN (occr->insn) != dominated && occr)
6139 /* Should never happen. */
6145 set = single_set (insn);
6149 /* Create a pseudo-reg to store the result of reaching
6150 expressions into. Get the mode for the new pseudo
6151 from the mode of the original destination pseudo. */
6152 if (expr->reaching_reg == NULL)
6154 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
6156 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
6158 occr->deleted_p = 1;
6159 if (!insn_inserted_p)
6161 insert_insn_end_bb (index_map[i], bb, 0);
6162 insn_inserted_p = 1;
6174 /* Top level routine to perform one code hoisting (aka unification) pass
6176 Return non-zero if a change was made. */
6179 one_code_hoisting_pass ()
6183 alloc_expr_hash_table (max_cuid);
6184 compute_expr_hash_table ();
6186 dump_hash_table (gcse_file, "Code Hosting Expressions", expr_hash_table,
6187 expr_hash_table_size, n_exprs);
6191 alloc_code_hoist_mem (last_basic_block, n_exprs);
6192 compute_code_hoist_data ();
6194 free_code_hoist_mem ();
6197 free_expr_hash_table ();
6202 /* Here we provide the things required to do store motion towards
6203 the exit. In order for this to be effective, gcse also needed to
6204 be taught how to move a load when it is kill only by a store to itself.
6209 void foo(float scale)
6211 for (i=0; i<10; i++)
6215 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
6216 the load out since its live around the loop, and stored at the bottom
6219 The 'Load Motion' referred to and implemented in this file is
6220 an enhancement to gcse which when using edge based lcm, recognizes
6221 this situation and allows gcse to move the load out of the loop.
6223 Once gcse has hoisted the load, store motion can then push this
6224 load towards the exit, and we end up with no loads or stores of 'i'
6227 /* This will search the ldst list for a matching expression. If it
6228 doesn't find one, we create one and initialize it. */
6230 static struct ls_expr *
6234 struct ls_expr * ptr;
6236 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
6237 if (expr_equiv_p (ptr->pattern, x))
6242 ptr = (struct ls_expr *) xmalloc (sizeof (struct ls_expr));
6244 ptr->next = pre_ldst_mems;
6247 ptr->loads = NULL_RTX;
6248 ptr->stores = NULL_RTX;
6249 ptr->reaching_reg = NULL_RTX;
6252 ptr->hash_index = 0;
6253 pre_ldst_mems = ptr;
6259 /* Free up an individual ldst entry. */
6262 free_ldst_entry (ptr)
6263 struct ls_expr * ptr;
6265 free_INSN_LIST_list (& ptr->loads);
6266 free_INSN_LIST_list (& ptr->stores);
6271 /* Free up all memory associated with the ldst list. */
6276 while (pre_ldst_mems)
6278 struct ls_expr * tmp = pre_ldst_mems;
6280 pre_ldst_mems = pre_ldst_mems->next;
6282 free_ldst_entry (tmp);
6285 pre_ldst_mems = NULL;
6288 /* Dump debugging info about the ldst list. */
6291 print_ldst_list (file)
6294 struct ls_expr * ptr;
6296 fprintf (file, "LDST list: \n");
6298 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
6300 fprintf (file, " Pattern (%3d): ", ptr->index);
6302 print_rtl (file, ptr->pattern);
6304 fprintf (file, "\n Loads : ");
6307 print_rtl (file, ptr->loads);
6309 fprintf (file, "(nil)");
6311 fprintf (file, "\n Stores : ");
6314 print_rtl (file, ptr->stores);
6316 fprintf (file, "(nil)");
6318 fprintf (file, "\n\n");
6321 fprintf (file, "\n");
6324 /* Returns 1 if X is in the list of ldst only expressions. */
6326 static struct ls_expr *
6327 find_rtx_in_ldst (x)
6330 struct ls_expr * ptr;
6332 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6333 if (expr_equiv_p (ptr->pattern, x) && ! ptr->invalid)
6339 /* Assign each element of the list of mems a monotonically increasing value. */
6344 struct ls_expr * ptr;
6347 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6353 /* Return first item in the list. */
6355 static inline struct ls_expr *
6358 return pre_ldst_mems;
6361 /* Return the next item in ther list after the specified one. */
6363 static inline struct ls_expr *
6365 struct ls_expr * ptr;
6370 /* Load Motion for loads which only kill themselves. */
6372 /* Return true if x is a simple MEM operation, with no registers or
6373 side effects. These are the types of loads we consider for the
6374 ld_motion list, otherwise we let the usual aliasing take care of it. */
6380 if (GET_CODE (x) != MEM)
6383 if (MEM_VOLATILE_P (x))
6386 if (GET_MODE (x) == BLKmode)
6389 if (!rtx_varies_p (XEXP (x, 0), 0))
6395 /* Make sure there isn't a buried reference in this pattern anywhere.
6396 If there is, invalidate the entry for it since we're not capable
6397 of fixing it up just yet.. We have to be sure we know about ALL
6398 loads since the aliasing code will allow all entries in the
6399 ld_motion list to not-alias itself. If we miss a load, we will get
6400 the wrong value since gcse might common it and we won't know to
6404 invalidate_any_buried_refs (x)
6409 struct ls_expr * ptr;
6411 /* Invalidate it in the list. */
6412 if (GET_CODE (x) == MEM && simple_mem (x))
6414 ptr = ldst_entry (x);
6418 /* Recursively process the insn. */
6419 fmt = GET_RTX_FORMAT (GET_CODE (x));
6421 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
6424 invalidate_any_buried_refs (XEXP (x, i));
6425 else if (fmt[i] == 'E')
6426 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6427 invalidate_any_buried_refs (XVECEXP (x, i, j));
6431 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
6432 being defined as MEM loads and stores to symbols, with no
6433 side effects and no registers in the expression. If there are any
6434 uses/defs which don't match this criteria, it is invalidated and
6435 trimmed out later. */
6438 compute_ld_motion_mems ()
6440 struct ls_expr * ptr;
6444 pre_ldst_mems = NULL;
6448 for (insn = bb->head;
6449 insn && insn != NEXT_INSN (bb->end);
6450 insn = NEXT_INSN (insn))
6452 if (GET_RTX_CLASS (GET_CODE (insn)) == 'i')
6454 if (GET_CODE (PATTERN (insn)) == SET)
6456 rtx src = SET_SRC (PATTERN (insn));
6457 rtx dest = SET_DEST (PATTERN (insn));
6459 /* Check for a simple LOAD... */
6460 if (GET_CODE (src) == MEM && simple_mem (src))
6462 ptr = ldst_entry (src);
6463 if (GET_CODE (dest) == REG)
6464 ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
6470 /* Make sure there isn't a buried load somewhere. */
6471 invalidate_any_buried_refs (src);
6474 /* Check for stores. Don't worry about aliased ones, they
6475 will block any movement we might do later. We only care
6476 about this exact pattern since those are the only
6477 circumstance that we will ignore the aliasing info. */
6478 if (GET_CODE (dest) == MEM && simple_mem (dest))
6480 ptr = ldst_entry (dest);
6482 if (GET_CODE (src) != MEM
6483 && GET_CODE (src) != ASM_OPERANDS)
6484 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
6490 invalidate_any_buried_refs (PATTERN (insn));
6496 /* Remove any references that have been either invalidated or are not in the
6497 expression list for pre gcse. */
6500 trim_ld_motion_mems ()
6502 struct ls_expr * last = NULL;
6503 struct ls_expr * ptr = first_ls_expr ();
6507 int del = ptr->invalid;
6508 struct expr * expr = NULL;
6510 /* Delete if entry has been made invalid. */
6516 /* Delete if we cannot find this mem in the expression list. */
6517 for (i = 0; i < expr_hash_table_size && del; i++)
6519 for (expr = expr_hash_table[i];
6521 expr = expr->next_same_hash)
6522 if (expr_equiv_p (expr->expr, ptr->pattern))
6534 last->next = ptr->next;
6535 free_ldst_entry (ptr);
6540 pre_ldst_mems = pre_ldst_mems->next;
6541 free_ldst_entry (ptr);
6542 ptr = pre_ldst_mems;
6547 /* Set the expression field if we are keeping it. */
6554 /* Show the world what we've found. */
6555 if (gcse_file && pre_ldst_mems != NULL)
6556 print_ldst_list (gcse_file);
6559 /* This routine will take an expression which we are replacing with
6560 a reaching register, and update any stores that are needed if
6561 that expression is in the ld_motion list. Stores are updated by
6562 copying their SRC to the reaching register, and then storeing
6563 the reaching register into the store location. These keeps the
6564 correct value in the reaching register for the loads. */
6567 update_ld_motion_stores (expr)
6570 struct ls_expr * mem_ptr;
6572 if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
6574 /* We can try to find just the REACHED stores, but is shouldn't
6575 matter to set the reaching reg everywhere... some might be
6576 dead and should be eliminated later. */
6578 /* We replace SET mem = expr with
6580 SET mem = reg , where reg is the
6581 reaching reg used in the load. */
6582 rtx list = mem_ptr->stores;
6584 for ( ; list != NULL_RTX; list = XEXP (list, 1))
6586 rtx insn = XEXP (list, 0);
6587 rtx pat = PATTERN (insn);
6588 rtx src = SET_SRC (pat);
6589 rtx reg = expr->reaching_reg;
6592 /* If we've already copied it, continue. */
6593 if (expr->reaching_reg == src)
6598 fprintf (gcse_file, "PRE: store updated with reaching reg ");
6599 print_rtl (gcse_file, expr->reaching_reg);
6600 fprintf (gcse_file, ":\n ");
6601 print_inline_rtx (gcse_file, insn, 8);
6602 fprintf (gcse_file, "\n");
6605 copy = gen_move_insn ( reg, SET_SRC (pat));
6606 new = emit_insn_before (copy, insn);
6607 record_one_set (REGNO (reg), new);
6608 SET_SRC (pat) = reg;
6610 /* un-recognize this pattern since it's probably different now. */
6611 INSN_CODE (insn) = -1;
6612 gcse_create_count++;
6617 /* Store motion code. */
6619 /* This is used to communicate the target bitvector we want to use in the
6620 reg_set_info routine when called via the note_stores mechanism. */
6621 static sbitmap * regvec;
6623 /* Used in computing the reverse edge graph bit vectors. */
6624 static sbitmap * st_antloc;
6626 /* Global holding the number of store expressions we are dealing with. */
6627 static int num_stores;
6629 /* Checks to set if we need to mark a register set. Called from note_stores. */
6632 reg_set_info (dest, setter, data)
6633 rtx dest, setter ATTRIBUTE_UNUSED;
6634 void * data ATTRIBUTE_UNUSED;
6636 if (GET_CODE (dest) == SUBREG)
6637 dest = SUBREG_REG (dest);
6639 if (GET_CODE (dest) == REG)
6640 SET_BIT (*regvec, REGNO (dest));
6643 /* Return non-zero if the register operands of expression X are killed
6644 anywhere in basic block BB. */
6647 store_ops_ok (x, bb)
6655 /* Repeat is used to turn tail-recursion into iteration. */
6661 code = GET_CODE (x);
6665 /* If a reg has changed after us in this
6666 block, the operand has been killed. */
6667 return TEST_BIT (reg_set_in_block[bb->index], REGNO (x));
6695 i = GET_RTX_LENGTH (code) - 1;
6696 fmt = GET_RTX_FORMAT (code);
6702 rtx tem = XEXP (x, i);
6704 /* If we are about to do the last recursive call
6705 needed at this level, change it into iteration.
6706 This function is called enough to be worth it. */
6713 if (! store_ops_ok (tem, bb))
6716 else if (fmt[i] == 'E')
6720 for (j = 0; j < XVECLEN (x, i); j++)
6722 if (! store_ops_ok (XVECEXP (x, i, j), bb))
6731 /* Determine whether insn is MEM store pattern that we will consider moving. */
6734 find_moveable_store (insn)
6737 struct ls_expr * ptr;
6738 rtx dest = PATTERN (insn);
6740 if (GET_CODE (dest) != SET
6741 || GET_CODE (SET_SRC (dest)) == ASM_OPERANDS)
6744 dest = SET_DEST (dest);
6746 if (GET_CODE (dest) != MEM || MEM_VOLATILE_P (dest)
6747 || GET_MODE (dest) == BLKmode)
6750 if (GET_CODE (XEXP (dest, 0)) != SYMBOL_REF)
6753 if (rtx_varies_p (XEXP (dest, 0), 0))
6756 ptr = ldst_entry (dest);
6757 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
6760 /* Perform store motion. Much like gcse, except we move expressions the
6761 other way by looking at the flowgraph in reverse. */
6764 compute_store_table ()
6771 max_gcse_regno = max_reg_num ();
6773 reg_set_in_block = (sbitmap *) sbitmap_vector_alloc (last_basic_block,
6775 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
6778 /* Find all the stores we care about. */
6781 regvec = & (reg_set_in_block[bb->index]);
6782 for (insn = bb->end;
6783 insn && insn != PREV_INSN (bb->end);
6784 insn = PREV_INSN (insn))
6786 /* Ignore anything that is not a normal insn. */
6787 if (! INSN_P (insn))
6790 if (GET_CODE (insn) == CALL_INSN)
6792 bool clobbers_all = false;
6793 #ifdef NON_SAVING_SETJMP
6794 if (NON_SAVING_SETJMP
6795 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
6796 clobbers_all = true;
6799 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
6801 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
6802 SET_BIT (reg_set_in_block[bb->index], regno);
6805 pat = PATTERN (insn);
6806 note_stores (pat, reg_set_info, NULL);
6808 /* Now that we've marked regs, look for stores. */
6809 if (GET_CODE (pat) == SET)
6810 find_moveable_store (insn);
6814 ret = enumerate_ldsts ();
6818 fprintf (gcse_file, "Store Motion Expressions.\n");
6819 print_ldst_list (gcse_file);
6825 /* Check to see if the load X is aliased with STORE_PATTERN. */
6828 load_kills_store (x, store_pattern)
6829 rtx x, store_pattern;
6831 if (true_dependence (x, GET_MODE (x), store_pattern, rtx_addr_varies_p))
6836 /* Go through the entire insn X, looking for any loads which might alias
6837 STORE_PATTERN. Return 1 if found. */
6840 find_loads (x, store_pattern)
6841 rtx x, store_pattern;
6850 if (GET_CODE (x) == SET)
6853 if (GET_CODE (x) == MEM)
6855 if (load_kills_store (x, store_pattern))
6859 /* Recursively process the insn. */
6860 fmt = GET_RTX_FORMAT (GET_CODE (x));
6862 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
6865 ret |= find_loads (XEXP (x, i), store_pattern);
6866 else if (fmt[i] == 'E')
6867 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6868 ret |= find_loads (XVECEXP (x, i, j), store_pattern);
6873 /* Check if INSN kills the store pattern X (is aliased with it).
6874 Return 1 if it it does. */
6877 store_killed_in_insn (x, insn)
6880 if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
6883 if (GET_CODE (insn) == CALL_INSN)
6885 /* A normal or pure call might read from pattern,
6886 but a const call will not. */
6887 return ! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn);
6890 if (GET_CODE (PATTERN (insn)) == SET)
6892 rtx pat = PATTERN (insn);
6893 /* Check for memory stores to aliased objects. */
6894 if (GET_CODE (SET_DEST (pat)) == MEM && !expr_equiv_p (SET_DEST (pat), x))
6895 /* pretend its a load and check for aliasing. */
6896 if (find_loads (SET_DEST (pat), x))
6898 return find_loads (SET_SRC (pat), x);
6901 return find_loads (PATTERN (insn), x);
6904 /* Returns 1 if the expression X is loaded or clobbered on or after INSN
6905 within basic block BB. */
6908 store_killed_after (x, insn, bb)
6917 /* Check if the register operands of the store are OK in this block.
6918 Note that if registers are changed ANYWHERE in the block, we'll
6919 decide we can't move it, regardless of whether it changed above
6920 or below the store. This could be improved by checking the register
6921 operands while lookinng for aliasing in each insn. */
6922 if (!store_ops_ok (XEXP (x, 0), bb))
6925 for ( ; insn && insn != NEXT_INSN (last); insn = NEXT_INSN (insn))
6926 if (store_killed_in_insn (x, insn))
6932 /* Returns 1 if the expression X is loaded or clobbered on or before INSN
6933 within basic block BB. */
6935 store_killed_before (x, insn, bb)
6939 rtx first = bb->head;
6942 return store_killed_in_insn (x, insn);
6944 /* Check if the register operands of the store are OK in this block.
6945 Note that if registers are changed ANYWHERE in the block, we'll
6946 decide we can't move it, regardless of whether it changed above
6947 or below the store. This could be improved by checking the register
6948 operands while lookinng for aliasing in each insn. */
6949 if (!store_ops_ok (XEXP (x, 0), bb))
6952 for ( ; insn && insn != PREV_INSN (first); insn = PREV_INSN (insn))
6953 if (store_killed_in_insn (x, insn))
6959 #define ANTIC_STORE_LIST(x) ((x)->loads)
6960 #define AVAIL_STORE_LIST(x) ((x)->stores)
6962 /* Given the table of available store insns at the end of blocks,
6963 determine which ones are not killed by aliasing, and generate
6964 the appropriate vectors for gen and killed. */
6966 build_store_vectors ()
6970 struct ls_expr * ptr;
6972 /* Build the gen_vector. This is any store in the table which is not killed
6973 by aliasing later in its block. */
6974 ae_gen = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
6975 sbitmap_vector_zero (ae_gen, last_basic_block);
6977 st_antloc = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
6978 sbitmap_vector_zero (st_antloc, last_basic_block);
6980 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6982 /* Put all the stores into either the antic list, or the avail list,
6984 rtx store_list = ptr->stores;
6985 ptr->stores = NULL_RTX;
6987 for (st = store_list; st != NULL; st = XEXP (st, 1))
6989 insn = XEXP (st, 0);
6990 bb = BLOCK_FOR_INSN (insn);
6992 if (!store_killed_after (ptr->pattern, insn, bb))
6994 /* If we've already seen an availale expression in this block,
6995 we can delete the one we saw already (It occurs earlier in
6996 the block), and replace it with this one). We'll copy the
6997 old SRC expression to an unused register in case there
6998 are any side effects. */
6999 if (TEST_BIT (ae_gen[bb->index], ptr->index))
7001 /* Find previous store. */
7003 for (st = AVAIL_STORE_LIST (ptr); st ; st = XEXP (st, 1))
7004 if (BLOCK_FOR_INSN (XEXP (st, 0)) == bb)
7008 rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
7010 fprintf (gcse_file, "Removing redundant store:\n");
7011 replace_store_insn (r, XEXP (st, 0), bb);
7012 XEXP (st, 0) = insn;
7016 SET_BIT (ae_gen[bb->index], ptr->index);
7017 AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn,
7018 AVAIL_STORE_LIST (ptr));
7021 if (!store_killed_before (ptr->pattern, insn, bb))
7023 SET_BIT (st_antloc[BLOCK_NUM (insn)], ptr->index);
7024 ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (insn,
7025 ANTIC_STORE_LIST (ptr));
7029 /* Free the original list of store insns. */
7030 free_INSN_LIST_list (&store_list);
7033 ae_kill = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
7034 sbitmap_vector_zero (ae_kill, last_basic_block);
7036 transp = (sbitmap *) sbitmap_vector_alloc (last_basic_block, num_stores);
7037 sbitmap_vector_zero (transp, last_basic_block);
7039 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7042 if (store_killed_after (ptr->pattern, b->head, b))
7044 /* The anticipatable expression is not killed if it's gen'd. */
7046 We leave this check out for now. If we have a code sequence
7047 in a block which looks like:
7051 We should flag this as having an ANTIC expression, NOT
7052 transparent, NOT killed, and AVAIL.
7053 Unfortunately, since we haven't re-written all loads to
7054 use the reaching reg, we'll end up doing an incorrect
7055 Load in the middle here if we push the store down. It happens in
7056 gcc.c-torture/execute/960311-1.c with -O3
7057 If we always kill it in this case, we'll sometimes do
7058 uneccessary work, but it shouldn't actually hurt anything.
7059 if (!TEST_BIT (ae_gen[b], ptr->index)). */
7060 SET_BIT (ae_kill[b->index], ptr->index);
7063 SET_BIT (transp[b->index], ptr->index);
7066 /* Any block with no exits calls some non-returning function, so
7067 we better mark the store killed here, or we might not store to
7068 it at all. If we knew it was abort, we wouldn't have to store,
7069 but we don't know that for sure. */
7072 fprintf (gcse_file, "ST_avail and ST_antic (shown under loads..)\n");
7073 print_ldst_list (gcse_file);
7074 dump_sbitmap_vector (gcse_file, "st_antloc", "", st_antloc, last_basic_block);
7075 dump_sbitmap_vector (gcse_file, "st_kill", "", ae_kill, last_basic_block);
7076 dump_sbitmap_vector (gcse_file, "Transpt", "", transp, last_basic_block);
7077 dump_sbitmap_vector (gcse_file, "st_avloc", "", ae_gen, last_basic_block);
7081 /* Insert an instruction at the begining of a basic block, and update
7082 the BLOCK_HEAD if needed. */
7085 insert_insn_start_bb (insn, bb)
7089 /* Insert at start of successor block. */
7090 rtx prev = PREV_INSN (bb->head);
7091 rtx before = bb->head;
7094 if (GET_CODE (before) != CODE_LABEL
7095 && (GET_CODE (before) != NOTE
7096 || NOTE_LINE_NUMBER (before) != NOTE_INSN_BASIC_BLOCK))
7099 if (prev == bb->end)
7101 before = NEXT_INSN (before);
7104 insn = emit_insn_after (insn, prev);
7108 fprintf (gcse_file, "STORE_MOTION insert store at start of BB %d:\n",
7110 print_inline_rtx (gcse_file, insn, 6);
7111 fprintf (gcse_file, "\n");
7115 /* This routine will insert a store on an edge. EXPR is the ldst entry for
7116 the memory reference, and E is the edge to insert it on. Returns non-zero
7117 if an edge insertion was performed. */
7120 insert_store (expr, e)
7121 struct ls_expr * expr;
7128 /* We did all the deleted before this insert, so if we didn't delete a
7129 store, then we haven't set the reaching reg yet either. */
7130 if (expr->reaching_reg == NULL_RTX)
7133 reg = expr->reaching_reg;
7134 insn = gen_move_insn (expr->pattern, reg);
7136 /* If we are inserting this expression on ALL predecessor edges of a BB,
7137 insert it at the start of the BB, and reset the insert bits on the other
7138 edges so we don't try to insert it on the other edges. */
7140 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
7142 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
7143 if (index == EDGE_INDEX_NO_EDGE)
7145 if (! TEST_BIT (pre_insert_map[index], expr->index))
7149 /* If tmp is NULL, we found an insertion on every edge, blank the
7150 insertion vector for these edges, and insert at the start of the BB. */
7151 if (!tmp && bb != EXIT_BLOCK_PTR)
7153 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
7155 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
7156 RESET_BIT (pre_insert_map[index], expr->index);
7158 insert_insn_start_bb (insn, bb);
7162 /* We can't insert on this edge, so we'll insert at the head of the
7163 successors block. See Morgan, sec 10.5. */
7164 if ((e->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
7166 insert_insn_start_bb (insn, bb);
7170 insert_insn_on_edge (insn, e);
7174 fprintf (gcse_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
7175 e->src->index, e->dest->index);
7176 print_inline_rtx (gcse_file, insn, 6);
7177 fprintf (gcse_file, "\n");
7183 /* This routine will replace a store with a SET to a specified register. */
7186 replace_store_insn (reg, del, bb)
7192 insn = gen_move_insn (reg, SET_SRC (PATTERN (del)));
7193 insn = emit_insn_after (insn, del);
7198 "STORE_MOTION delete insn in BB %d:\n ", bb->index);
7199 print_inline_rtx (gcse_file, del, 6);
7200 fprintf (gcse_file, "\nSTORE MOTION replaced with insn:\n ");
7201 print_inline_rtx (gcse_file, insn, 6);
7202 fprintf (gcse_file, "\n");
7209 /* Delete a store, but copy the value that would have been stored into
7210 the reaching_reg for later storing. */
7213 delete_store (expr, bb)
7214 struct ls_expr * expr;
7219 if (expr->reaching_reg == NULL_RTX)
7220 expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
7223 /* If there is more than 1 store, the earlier ones will be dead,
7224 but it doesn't hurt to replace them here. */
7225 reg = expr->reaching_reg;
7227 for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
7230 if (BLOCK_FOR_INSN (del) == bb)
7232 /* We know there is only one since we deleted redundant
7233 ones during the available computation. */
7234 replace_store_insn (reg, del, bb);
7240 /* Free memory used by store motion. */
7243 free_store_memory ()
7248 sbitmap_vector_free (ae_gen);
7250 sbitmap_vector_free (ae_kill);
7252 sbitmap_vector_free (transp);
7254 sbitmap_vector_free (st_antloc);
7256 sbitmap_vector_free (pre_insert_map);
7258 sbitmap_vector_free (pre_delete_map);
7259 if (reg_set_in_block)
7260 sbitmap_vector_free (reg_set_in_block);
7262 ae_gen = ae_kill = transp = st_antloc = NULL;
7263 pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
7266 /* Perform store motion. Much like gcse, except we move expressions the
7267 other way by looking at the flowgraph in reverse. */
7274 struct ls_expr * ptr;
7275 int update_flow = 0;
7279 fprintf (gcse_file, "before store motion\n");
7280 print_rtl (gcse_file, get_insns ());
7284 init_alias_analysis ();
7286 /* Find all the stores that are live to the end of their block. */
7287 num_stores = compute_store_table ();
7288 if (num_stores == 0)
7290 sbitmap_vector_free (reg_set_in_block);
7291 end_alias_analysis ();
7295 /* Now compute whats actually available to move. */
7296 add_noreturn_fake_exit_edges ();
7297 build_store_vectors ();
7299 edge_list = pre_edge_rev_lcm (gcse_file, num_stores, transp, ae_gen,
7300 st_antloc, ae_kill, &pre_insert_map,
7303 /* Now we want to insert the new stores which are going to be needed. */
7304 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7307 if (TEST_BIT (pre_delete_map[bb->index], ptr->index))
7308 delete_store (ptr, bb);
7310 for (x = 0; x < NUM_EDGES (edge_list); x++)
7311 if (TEST_BIT (pre_insert_map[x], ptr->index))
7312 update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
7316 commit_edge_insertions ();
7318 free_store_memory ();
7319 free_edge_list (edge_list);
7320 remove_fake_edges ();
7321 end_alias_analysis ();
7324 #include "gt-gcse.h"