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, 2003
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.
148 #include "coretypes.h"
156 #include "hard-reg-set.h"
159 #include "insn-config.h"
161 #include "basic-block.h"
163 #include "function.h"
164 #include "langhooks.h"
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 struct reg_use {rtx reg_rtx; };
306 /* Hash table of expressions. */
310 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
312 /* Index in the available expression bitmaps. */
314 /* Next entry with the same hash. */
315 struct expr *next_same_hash;
316 /* List of anticipatable occurrences in basic blocks in the function.
317 An "anticipatable occurrence" is one that is the first occurrence in the
318 basic block, the operands are not modified in the basic block prior
319 to the occurrence and the output is not used between the start of
320 the block and the occurrence. */
321 struct occr *antic_occr;
322 /* List of available occurrence in basic blocks in the function.
323 An "available occurrence" is one that is the last occurrence in the
324 basic block and the operands are not modified by following statements in
325 the basic block [including this insn]. */
326 struct occr *avail_occr;
327 /* Non-null if the computation is PRE redundant.
328 The value is the newly created pseudo-reg to record a copy of the
329 expression in all the places that reach the redundant copy. */
333 /* Occurrence of an expression.
334 There is one per basic block. If a pattern appears more than once the
335 last appearance is used [or first for anticipatable expressions]. */
339 /* Next occurrence of this expression. */
341 /* The insn that computes the expression. */
343 /* Nonzero if this [anticipatable] occurrence has been deleted. */
345 /* Nonzero if this [available] occurrence has been copied to
347 /* ??? This is mutually exclusive with deleted_p, so they could share
352 /* Expression and copy propagation hash tables.
353 Each hash table is an array of buckets.
354 ??? It is known that if it were an array of entries, structure elements
355 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
356 not clear whether in the final analysis a sufficient amount of memory would
357 be saved as the size of the available expression bitmaps would be larger
358 [one could build a mapping table without holes afterwards though].
359 Someday I'll perform the computation and figure it out. */
364 This is an array of `expr_hash_table_size' elements. */
367 /* Size of the hash table, in elements. */
370 /* Number of hash table elements. */
371 unsigned int n_elems;
373 /* Whether the table is expression of copy propagation one. */
377 /* Expression hash table. */
378 static struct hash_table expr_hash_table;
380 /* Copy propagation hash table. */
381 static struct hash_table 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 /* Table of registers that are modified.
413 For each register, each element is a list of places where the pseudo-reg
416 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
417 requires knowledge of which blocks kill which regs [and thus could use
418 a bitmap instead of the lists `reg_set_table' uses].
420 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
421 num-regs) [however perhaps it may be useful to keep the data as is]. One
422 advantage of recording things this way is that `reg_set_table' is fairly
423 sparse with respect to pseudo regs but for hard regs could be fairly dense
424 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
425 up functions like compute_transp since in the case of pseudo-regs we only
426 need to iterate over the number of times a pseudo-reg is set, not over the
427 number of basic blocks [clearly there is a bit of a slow down in the cases
428 where a pseudo is set more than once in a block, however it is believed
429 that the net effect is to speed things up]. This isn't done for hard-regs
430 because recording call-clobbered hard-regs in `reg_set_table' at each
431 function call can consume a fair bit of memory, and iterating over
432 hard-regs stored this way in compute_transp will be more expensive. */
434 typedef struct reg_set
436 /* The next setting of this register. */
437 struct reg_set *next;
438 /* The insn where it was set. */
442 static reg_set **reg_set_table;
444 /* Size of `reg_set_table'.
445 The table starts out at max_gcse_regno + slop, and is enlarged as
447 static int reg_set_table_size;
449 /* Amount to grow `reg_set_table' by when it's full. */
450 #define REG_SET_TABLE_SLOP 100
452 /* This is a list of expressions which are MEMs and will be used by load
454 Load motion tracks MEMs which aren't killed by
455 anything except itself. (ie, loads and stores to a single location).
456 We can then allow movement of these MEM refs with a little special
457 allowance. (all stores copy the same value to the reaching reg used
458 for the loads). This means all values used to store into memory must have
459 no side effects so we can re-issue the setter value.
460 Store Motion uses this structure as an expression table to track stores
461 which look interesting, and might be moveable towards the exit block. */
465 struct expr * expr; /* Gcse expression reference for LM. */
466 rtx pattern; /* Pattern of this mem. */
467 rtx pattern_regs; /* List of registers mentioned by the mem. */
468 rtx loads; /* INSN list of loads seen. */
469 rtx stores; /* INSN list of stores seen. */
470 struct ls_expr * next; /* Next in the list. */
471 int invalid; /* Invalid for some reason. */
472 int index; /* If it maps to a bitmap index. */
473 unsigned int hash_index; /* Index when in a hash table. */
474 rtx reaching_reg; /* Register to use when re-writing. */
477 /* Array of implicit set patterns indexed by basic block index. */
478 static rtx *implicit_sets;
480 /* Head of the list of load/store memory refs. */
481 static struct ls_expr * pre_ldst_mems = NULL;
483 /* Bitmap containing one bit for each register in the program.
484 Used when performing GCSE to track which registers have been set since
485 the start of the basic block. */
486 static regset reg_set_bitmap;
488 /* For each block, a bitmap of registers set in the block.
489 This is used by expr_killed_p and compute_transp.
490 It is computed during hash table computation and not by compute_sets
491 as it includes registers added since the last pass (or between cprop and
492 gcse) and it's currently not easy to realloc sbitmap vectors. */
493 static sbitmap *reg_set_in_block;
495 /* Array, indexed by basic block number for a list of insns which modify
496 memory within that block. */
497 static rtx * modify_mem_list;
498 bitmap modify_mem_list_set;
500 /* This array parallels modify_mem_list, but is kept canonicalized. */
501 static rtx * canon_modify_mem_list;
502 bitmap canon_modify_mem_list_set;
503 /* Various variables for statistics gathering. */
505 /* Memory used in a pass.
506 This isn't intended to be absolutely precise. Its intent is only
507 to keep an eye on memory usage. */
508 static int bytes_used;
510 /* GCSE substitutions made. */
511 static int gcse_subst_count;
512 /* Number of copy instructions created. */
513 static int gcse_create_count;
514 /* Number of constants propagated. */
515 static int const_prop_count;
516 /* Number of copys propagated. */
517 static int copy_prop_count;
519 /* These variables are used by classic GCSE.
520 Normally they'd be defined a bit later, but `rd_gen' needs to
521 be declared sooner. */
523 /* Each block has a bitmap of each type.
524 The length of each blocks bitmap is:
526 max_cuid - for reaching definitions
527 n_exprs - for available expressions
529 Thus we view the bitmaps as 2 dimensional arrays. i.e.
530 rd_kill[block_num][cuid_num]
531 ae_kill[block_num][expr_num] */
533 /* For reaching defs */
534 static sbitmap *rd_kill, *rd_gen, *reaching_defs, *rd_out;
536 /* for available exprs */
537 static sbitmap *ae_kill, *ae_gen, *ae_in, *ae_out;
539 /* Objects of this type are passed around by the null-pointer check
541 struct null_pointer_info
543 /* The basic block being processed. */
544 basic_block current_block;
545 /* The first register to be handled in this pass. */
546 unsigned int min_reg;
547 /* One greater than the last register to be handled in this pass. */
548 unsigned int max_reg;
549 sbitmap *nonnull_local;
550 sbitmap *nonnull_killed;
553 static void compute_can_copy (void);
554 static void *gmalloc (size_t) ATTRIBUTE_MALLOC;
555 static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC;
556 static void *grealloc (void *, size_t);
557 static void *gcse_alloc (unsigned long);
558 static void alloc_gcse_mem (rtx);
559 static void free_gcse_mem (void);
560 static void alloc_reg_set_mem (int);
561 static void free_reg_set_mem (void);
562 static int get_bitmap_width (int, int, int);
563 static void record_one_set (int, rtx);
564 static void replace_one_set (int, rtx, rtx);
565 static void record_set_info (rtx, rtx, void *);
566 static void compute_sets (rtx);
567 static void hash_scan_insn (rtx, struct hash_table *, int);
568 static void hash_scan_set (rtx, rtx, struct hash_table *);
569 static void hash_scan_clobber (rtx, rtx, struct hash_table *);
570 static void hash_scan_call (rtx, rtx, struct hash_table *);
571 static int want_to_gcse_p (rtx);
572 static bool gcse_constant_p (rtx);
573 static int oprs_unchanged_p (rtx, rtx, int);
574 static int oprs_anticipatable_p (rtx, rtx);
575 static int oprs_available_p (rtx, rtx);
576 static void insert_expr_in_table (rtx, enum machine_mode, rtx, int, int,
577 struct hash_table *);
578 static void insert_set_in_table (rtx, rtx, struct hash_table *);
579 static unsigned int hash_expr (rtx, enum machine_mode, int *, int);
580 static unsigned int hash_expr_1 (rtx, enum machine_mode, int *);
581 static unsigned int hash_string_1 (const char *);
582 static unsigned int hash_set (int, int);
583 static int expr_equiv_p (rtx, rtx);
584 static void record_last_reg_set_info (rtx, int);
585 static void record_last_mem_set_info (rtx);
586 static void record_last_set_info (rtx, rtx, void *);
587 static void compute_hash_table (struct hash_table *);
588 static void alloc_hash_table (int, struct hash_table *, int);
589 static void free_hash_table (struct hash_table *);
590 static void compute_hash_table_work (struct hash_table *);
591 static void dump_hash_table (FILE *, const char *, struct hash_table *);
592 static struct expr *lookup_expr (rtx, struct hash_table *);
593 static struct expr *lookup_set (unsigned int, struct hash_table *);
594 static struct expr *next_set (unsigned int, struct expr *);
595 static void reset_opr_set_tables (void);
596 static int oprs_not_set_p (rtx, rtx);
597 static void mark_call (rtx);
598 static void mark_set (rtx, rtx);
599 static void mark_clobber (rtx, rtx);
600 static void mark_oprs_set (rtx);
601 static void alloc_cprop_mem (int, int);
602 static void free_cprop_mem (void);
603 static void compute_transp (rtx, int, sbitmap *, int);
604 static void compute_transpout (void);
605 static void compute_local_properties (sbitmap *, sbitmap *, sbitmap *,
606 struct hash_table *);
607 static void compute_cprop_data (void);
608 static void find_used_regs (rtx *, void *);
609 static int try_replace_reg (rtx, rtx, rtx);
610 static struct expr *find_avail_set (int, rtx);
611 static int cprop_jump (basic_block, rtx, rtx, rtx, rtx);
612 static void mems_conflict_for_gcse_p (rtx, rtx, void *);
613 static int load_killed_in_block_p (basic_block, int, rtx, int);
614 static void canon_list_insert (rtx, rtx, void *);
615 static int cprop_insn (rtx, int);
616 static int cprop (int);
617 static void find_implicit_sets (void);
618 static int one_cprop_pass (int, int, int);
619 static bool constprop_register (rtx, rtx, rtx, int);
620 static struct expr *find_bypass_set (int, int);
621 static bool reg_killed_on_edge (rtx, edge);
622 static int bypass_block (basic_block, rtx, rtx);
623 static int bypass_conditional_jumps (void);
624 static void alloc_pre_mem (int, int);
625 static void free_pre_mem (void);
626 static void compute_pre_data (void);
627 static int pre_expr_reaches_here_p (basic_block, struct expr *,
629 static void insert_insn_end_bb (struct expr *, basic_block, int);
630 static void pre_insert_copy_insn (struct expr *, rtx);
631 static void pre_insert_copies (void);
632 static int pre_delete (void);
633 static int pre_gcse (void);
634 static int one_pre_gcse_pass (int);
635 static void add_label_notes (rtx, rtx);
636 static void alloc_code_hoist_mem (int, int);
637 static void free_code_hoist_mem (void);
638 static void compute_code_hoist_vbeinout (void);
639 static void compute_code_hoist_data (void);
640 static int hoist_expr_reaches_here_p (basic_block, int, basic_block, char *);
641 static void hoist_code (void);
642 static int one_code_hoisting_pass (void);
643 static void alloc_rd_mem (int, int);
644 static void free_rd_mem (void);
645 static void handle_rd_kill_set (rtx, int, basic_block);
646 static void compute_kill_rd (void);
647 static void compute_rd (void);
648 static void alloc_avail_expr_mem (int, int);
649 static void free_avail_expr_mem (void);
650 static void compute_ae_gen (struct hash_table *);
651 static int expr_killed_p (rtx, basic_block);
652 static void compute_ae_kill (sbitmap *, sbitmap *, struct hash_table *);
653 static int expr_reaches_here_p (struct occr *, struct expr *, basic_block,
655 static rtx computing_insn (struct expr *, rtx);
656 static int def_reaches_here_p (rtx, rtx);
657 static int can_disregard_other_sets (struct reg_set **, rtx, int);
658 static int handle_avail_expr (rtx, struct expr *);
659 static int classic_gcse (void);
660 static int one_classic_gcse_pass (int);
661 static void invalidate_nonnull_info (rtx, rtx, void *);
662 static int delete_null_pointer_checks_1 (unsigned int *, sbitmap *, sbitmap *,
663 struct null_pointer_info *);
664 static rtx process_insert_insn (struct expr *);
665 static int pre_edge_insert (struct edge_list *, struct expr **);
666 static int expr_reaches_here_p_work (struct occr *, struct expr *,
667 basic_block, int, char *);
668 static int pre_expr_reaches_here_p_work (basic_block, struct expr *,
669 basic_block, char *);
670 static struct ls_expr * ldst_entry (rtx);
671 static void free_ldst_entry (struct ls_expr *);
672 static void free_ldst_mems (void);
673 static void print_ldst_list (FILE *);
674 static struct ls_expr * find_rtx_in_ldst (rtx);
675 static int enumerate_ldsts (void);
676 static inline struct ls_expr * first_ls_expr (void);
677 static inline struct ls_expr * next_ls_expr (struct ls_expr *);
678 static int simple_mem (rtx);
679 static void invalidate_any_buried_refs (rtx);
680 static void compute_ld_motion_mems (void);
681 static void trim_ld_motion_mems (void);
682 static void update_ld_motion_stores (struct expr *);
683 static void reg_set_info (rtx, rtx, void *);
684 static void reg_clear_last_set (rtx, rtx, void *);
685 static bool store_ops_ok (rtx, int *);
686 static rtx extract_mentioned_regs (rtx);
687 static rtx extract_mentioned_regs_helper (rtx, rtx);
688 static void find_moveable_store (rtx, int *, int *);
689 static int compute_store_table (void);
690 static bool load_kills_store (rtx, rtx, int);
691 static bool find_loads (rtx, rtx, int);
692 static bool store_killed_in_insn (rtx, rtx, rtx, int);
693 static bool store_killed_after (rtx, rtx, rtx, basic_block, int *, rtx *);
694 static bool store_killed_before (rtx, rtx, rtx, basic_block, int *);
695 static void build_store_vectors (void);
696 static void insert_insn_start_bb (rtx, basic_block);
697 static int insert_store (struct ls_expr *, edge);
698 static void remove_reachable_equiv_notes (basic_block, struct ls_expr *);
699 static void replace_store_insn (rtx, rtx, basic_block, struct ls_expr *);
700 static void delete_store (struct ls_expr *, basic_block);
701 static void free_store_memory (void);
702 static void store_motion (void);
703 static void free_insn_expr_list_list (rtx *);
704 static void clear_modify_mem_tables (void);
705 static void free_modify_mem_tables (void);
706 static rtx gcse_emit_move_after (rtx, rtx, rtx);
707 static void local_cprop_find_used_regs (rtx *, void *);
708 static bool do_local_cprop (rtx, rtx, int, rtx*);
709 static bool adjust_libcall_notes (rtx, rtx, rtx, rtx*);
710 static void local_cprop_pass (int);
711 static bool is_too_expensive (const char *);
714 /* Entry point for global common subexpression elimination.
715 F is the first instruction in the function. */
718 gcse_main (rtx f, FILE *file)
721 /* Bytes used at start of pass. */
722 int initial_bytes_used;
723 /* Maximum number of bytes used by a pass. */
725 /* Point to release obstack data from for each pass. */
726 char *gcse_obstack_bottom;
728 /* We do not construct an accurate cfg in functions which call
729 setjmp, so just punt to be safe. */
730 if (current_function_calls_setjmp)
733 /* Assume that we do not need to run jump optimizations after gcse. */
734 run_jump_opt_after_gcse = 0;
736 /* For calling dump_foo fns from gdb. */
737 debug_stderr = stderr;
740 /* Identify the basic block information for this function, including
741 successors and predecessors. */
742 max_gcse_regno = max_reg_num ();
745 dump_flow_info (file);
747 /* Return if there's nothing to do, or it is too expensive. */
748 if (n_basic_blocks <= 1 || is_too_expensive (_("GCSE disabled")))
751 gcc_obstack_init (&gcse_obstack);
755 init_alias_analysis ();
756 /* Record where pseudo-registers are set. This data is kept accurate
757 during each pass. ??? We could also record hard-reg information here
758 [since it's unchanging], however it is currently done during hash table
761 It may be tempting to compute MEM set information here too, but MEM sets
762 will be subject to code motion one day and thus we need to compute
763 information about memory sets when we build the hash tables. */
765 alloc_reg_set_mem (max_gcse_regno);
769 initial_bytes_used = bytes_used;
771 gcse_obstack_bottom = gcse_alloc (1);
773 while (changed && pass < MAX_GCSE_PASSES)
777 fprintf (file, "GCSE pass %d\n\n", pass + 1);
779 /* Initialize bytes_used to the space for the pred/succ lists,
780 and the reg_set_table data. */
781 bytes_used = initial_bytes_used;
783 /* Each pass may create new registers, so recalculate each time. */
784 max_gcse_regno = max_reg_num ();
788 /* Don't allow constant propagation to modify jumps
790 changed = one_cprop_pass (pass + 1, 0, 0);
793 changed |= one_classic_gcse_pass (pass + 1);
796 changed |= one_pre_gcse_pass (pass + 1);
797 /* We may have just created new basic blocks. Release and
798 recompute various things which are sized on the number of
802 free_modify_mem_tables ();
803 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
804 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
807 alloc_reg_set_mem (max_reg_num ());
809 run_jump_opt_after_gcse = 1;
812 if (max_pass_bytes < bytes_used)
813 max_pass_bytes = bytes_used;
815 /* Free up memory, then reallocate for code hoisting. We can
816 not re-use the existing allocated memory because the tables
817 will not have info for the insns or registers created by
818 partial redundancy elimination. */
821 /* It does not make sense to run code hoisting unless we optimizing
822 for code size -- it rarely makes programs faster, and can make
823 them bigger if we did partial redundancy elimination (when optimizing
824 for space, we use a classic gcse algorithm instead of partial
825 redundancy algorithms). */
828 max_gcse_regno = max_reg_num ();
830 changed |= one_code_hoisting_pass ();
833 if (max_pass_bytes < bytes_used)
834 max_pass_bytes = bytes_used;
839 fprintf (file, "\n");
843 obstack_free (&gcse_obstack, gcse_obstack_bottom);
847 /* Do one last pass of copy propagation, including cprop into
848 conditional jumps. */
850 max_gcse_regno = max_reg_num ();
852 /* This time, go ahead and allow cprop to alter jumps. */
853 one_cprop_pass (pass + 1, 1, 0);
858 fprintf (file, "GCSE of %s: %d basic blocks, ",
859 (*lang_hooks.decl_printable_name) (current_function_decl, 2),
861 fprintf (file, "%d pass%s, %d bytes\n\n",
862 pass, pass > 1 ? "es" : "", max_pass_bytes);
865 obstack_free (&gcse_obstack, NULL);
867 /* We are finished with alias. */
868 end_alias_analysis ();
869 allocate_reg_info (max_reg_num (), FALSE, FALSE);
871 if (!optimize_size && flag_gcse_sm)
874 /* Record where pseudo-registers are set. */
875 return run_jump_opt_after_gcse;
878 /* Misc. utilities. */
880 /* Nonzero for each mode that supports (set (reg) (reg)).
881 This is trivially true for integer and floating point values.
882 It may or may not be true for condition codes. */
883 static char can_copy[(int) NUM_MACHINE_MODES];
885 /* Compute which modes support reg/reg copy operations. */
888 compute_can_copy (void)
891 #ifndef AVOID_CCMODE_COPIES
894 memset (can_copy, 0, NUM_MACHINE_MODES);
897 for (i = 0; i < NUM_MACHINE_MODES; i++)
898 if (GET_MODE_CLASS (i) == MODE_CC)
900 #ifdef AVOID_CCMODE_COPIES
903 reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1);
904 insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
905 if (recog (PATTERN (insn), insn, NULL) >= 0)
915 /* Returns whether the mode supports reg/reg copy operations. */
918 can_copy_p (enum machine_mode mode)
920 static bool can_copy_init_p = false;
922 if (! can_copy_init_p)
925 can_copy_init_p = true;
928 return can_copy[mode] != 0;
931 /* Cover function to xmalloc to record bytes allocated. */
934 gmalloc (size_t size)
937 return xmalloc (size);
940 /* Cover function to xcalloc to record bytes allocated. */
943 gcalloc (size_t nelem, size_t elsize)
945 bytes_used += nelem * elsize;
946 return xcalloc (nelem, elsize);
949 /* Cover function to xrealloc.
950 We don't record the additional size since we don't know it.
951 It won't affect memory usage stats much anyway. */
954 grealloc (void *ptr, size_t size)
956 return xrealloc (ptr, size);
959 /* Cover function to obstack_alloc. */
962 gcse_alloc (unsigned long size)
965 return obstack_alloc (&gcse_obstack, size);
968 /* Allocate memory for the cuid mapping array,
969 and reg/memory set tracking tables.
971 This is called at the start of each pass. */
974 alloc_gcse_mem (rtx f)
979 /* Find the largest UID and create a mapping from UIDs to CUIDs.
980 CUIDs are like UIDs except they increase monotonically, have no gaps,
981 and only apply to real insns. */
983 max_uid = get_max_uid ();
984 uid_cuid = gcalloc (max_uid + 1, sizeof (int));
985 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
988 uid_cuid[INSN_UID (insn)] = i++;
990 uid_cuid[INSN_UID (insn)] = i;
993 /* Create a table mapping cuids to insns. */
996 cuid_insn = gcalloc (max_cuid + 1, sizeof (rtx));
997 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
999 CUID_INSN (i++) = insn;
1001 /* Allocate vars to track sets of regs. */
1002 reg_set_bitmap = BITMAP_XMALLOC ();
1004 /* Allocate vars to track sets of regs, memory per block. */
1005 reg_set_in_block = sbitmap_vector_alloc (last_basic_block, max_gcse_regno);
1006 /* Allocate array to keep a list of insns which modify memory in each
1008 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
1009 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
1010 modify_mem_list_set = BITMAP_XMALLOC ();
1011 canon_modify_mem_list_set = BITMAP_XMALLOC ();
1014 /* Free memory allocated by alloc_gcse_mem. */
1017 free_gcse_mem (void)
1022 BITMAP_XFREE (reg_set_bitmap);
1024 sbitmap_vector_free (reg_set_in_block);
1025 free_modify_mem_tables ();
1026 BITMAP_XFREE (modify_mem_list_set);
1027 BITMAP_XFREE (canon_modify_mem_list_set);
1030 /* Many of the global optimization algorithms work by solving dataflow
1031 equations for various expressions. Initially, some local value is
1032 computed for each expression in each block. Then, the values across the
1033 various blocks are combined (by following flow graph edges) to arrive at
1034 global values. Conceptually, each set of equations is independent. We
1035 may therefore solve all the equations in parallel, solve them one at a
1036 time, or pick any intermediate approach.
1038 When you're going to need N two-dimensional bitmaps, each X (say, the
1039 number of blocks) by Y (say, the number of expressions), call this
1040 function. It's not important what X and Y represent; only that Y
1041 correspond to the things that can be done in parallel. This function will
1042 return an appropriate chunking factor C; you should solve C sets of
1043 equations in parallel. By going through this function, we can easily
1044 trade space against time; by solving fewer equations in parallel we use
1048 get_bitmap_width (int n, int x, int y)
1050 /* It's not really worth figuring out *exactly* how much memory will
1051 be used by a particular choice. The important thing is to get
1052 something approximately right. */
1053 size_t max_bitmap_memory = 10 * 1024 * 1024;
1055 /* The number of bytes we'd use for a single column of minimum
1057 size_t column_size = n * x * sizeof (SBITMAP_ELT_TYPE);
1059 /* Often, it's reasonable just to solve all the equations in
1061 if (column_size * SBITMAP_SET_SIZE (y) <= max_bitmap_memory)
1064 /* Otherwise, pick the largest width we can, without going over the
1066 return SBITMAP_ELT_BITS * ((max_bitmap_memory + column_size - 1)
1070 /* Compute the local properties of each recorded expression.
1072 Local properties are those that are defined by the block, irrespective of
1075 An expression is transparent in a block if its operands are not modified
1078 An expression is computed (locally available) in a block if it is computed
1079 at least once and expression would contain the same value if the
1080 computation was moved to the end of the block.
1082 An expression is locally anticipatable in a block if it is computed at
1083 least once and expression would contain the same value if the computation
1084 was moved to the beginning of the block.
1086 We call this routine for cprop, pre and code hoisting. They all compute
1087 basically the same information and thus can easily share this code.
1089 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1090 properties. If NULL, then it is not necessary to compute or record that
1091 particular property.
1093 TABLE controls which hash table to look at. If it is set hash table,
1094 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1098 compute_local_properties (sbitmap *transp, sbitmap *comp, sbitmap *antloc, struct hash_table *table)
1102 /* Initialize any bitmaps that were passed in. */
1106 sbitmap_vector_zero (transp, last_basic_block);
1108 sbitmap_vector_ones (transp, last_basic_block);
1112 sbitmap_vector_zero (comp, last_basic_block);
1114 sbitmap_vector_zero (antloc, last_basic_block);
1116 for (i = 0; i < table->size; i++)
1120 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
1122 int indx = expr->bitmap_index;
1125 /* The expression is transparent in this block if it is not killed.
1126 We start by assuming all are transparent [none are killed], and
1127 then reset the bits for those that are. */
1129 compute_transp (expr->expr, indx, transp, table->set_p);
1131 /* The occurrences recorded in antic_occr are exactly those that
1132 we want to set to nonzero in ANTLOC. */
1134 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
1136 SET_BIT (antloc[BLOCK_NUM (occr->insn)], indx);
1138 /* While we're scanning the table, this is a good place to
1140 occr->deleted_p = 0;
1143 /* The occurrences recorded in avail_occr are exactly those that
1144 we want to set to nonzero in COMP. */
1146 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
1148 SET_BIT (comp[BLOCK_NUM (occr->insn)], indx);
1150 /* While we're scanning the table, this is a good place to
1155 /* While we're scanning the table, this is a good place to
1157 expr->reaching_reg = 0;
1162 /* Register set information.
1164 `reg_set_table' records where each register is set or otherwise
1167 static struct obstack reg_set_obstack;
1170 alloc_reg_set_mem (int n_regs)
1172 reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
1173 reg_set_table = gcalloc (reg_set_table_size, sizeof (struct reg_set *));
1175 gcc_obstack_init (®_set_obstack);
1179 free_reg_set_mem (void)
1181 free (reg_set_table);
1182 obstack_free (®_set_obstack, NULL);
1185 /* An OLD_INSN that used to set REGNO was replaced by NEW_INSN.
1186 Update the corresponding `reg_set_table' entry accordingly.
1187 We assume that NEW_INSN is not already recorded in reg_set_table[regno]. */
1190 replace_one_set (int regno, rtx old_insn, rtx new_insn)
1192 struct reg_set *reg_info;
1193 if (regno >= reg_set_table_size)
1195 for (reg_info = reg_set_table[regno]; reg_info; reg_info = reg_info->next)
1196 if (reg_info->insn == old_insn)
1198 reg_info->insn = new_insn;
1203 /* Record REGNO in the reg_set table. */
1206 record_one_set (int regno, rtx insn)
1208 /* Allocate a new reg_set element and link it onto the list. */
1209 struct reg_set *new_reg_info;
1211 /* If the table isn't big enough, enlarge it. */
1212 if (regno >= reg_set_table_size)
1214 int new_size = regno + REG_SET_TABLE_SLOP;
1216 reg_set_table = grealloc (reg_set_table,
1217 new_size * sizeof (struct reg_set *));
1218 memset (reg_set_table + reg_set_table_size, 0,
1219 (new_size - reg_set_table_size) * sizeof (struct reg_set *));
1220 reg_set_table_size = new_size;
1223 new_reg_info = obstack_alloc (®_set_obstack, sizeof (struct reg_set));
1224 bytes_used += sizeof (struct reg_set);
1225 new_reg_info->insn = insn;
1226 new_reg_info->next = reg_set_table[regno];
1227 reg_set_table[regno] = new_reg_info;
1230 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1231 an insn. The DATA is really the instruction in which the SET is
1235 record_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
1237 rtx record_set_insn = (rtx) data;
1239 if (GET_CODE (dest) == REG && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
1240 record_one_set (REGNO (dest), record_set_insn);
1243 /* Scan the function and record each set of each pseudo-register.
1245 This is called once, at the start of the gcse pass. See the comments for
1246 `reg_set_table' for further documentation. */
1249 compute_sets (rtx f)
1253 for (insn = f; insn != 0; insn = NEXT_INSN (insn))
1255 note_stores (PATTERN (insn), record_set_info, insn);
1258 /* Hash table support. */
1260 struct reg_avail_info
1262 basic_block last_bb;
1267 static struct reg_avail_info *reg_avail_info;
1268 static basic_block current_bb;
1271 /* See whether X, the source of a set, is something we want to consider for
1274 static GTY(()) rtx test_insn;
1276 want_to_gcse_p (rtx x)
1278 int num_clobbers = 0;
1281 switch (GET_CODE (x))
1289 case CONSTANT_P_RTX:
1296 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1297 if (general_operand (x, GET_MODE (x)))
1299 else if (GET_MODE (x) == VOIDmode)
1302 /* Otherwise, check if we can make a valid insn from it. First initialize
1303 our test insn if we haven't already. */
1307 = make_insn_raw (gen_rtx_SET (VOIDmode,
1308 gen_rtx_REG (word_mode,
1309 FIRST_PSEUDO_REGISTER * 2),
1311 NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0;
1314 /* Now make an insn like the one we would make when GCSE'ing and see if
1316 PUT_MODE (SET_DEST (PATTERN (test_insn)), GET_MODE (x));
1317 SET_SRC (PATTERN (test_insn)) = x;
1318 return ((icode = recog (PATTERN (test_insn), test_insn, &num_clobbers)) >= 0
1319 && (num_clobbers == 0 || ! added_clobbers_hard_reg_p (icode)));
1322 /* Return nonzero if the operands of expression X are unchanged from the
1323 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1324 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1327 oprs_unchanged_p (rtx x, rtx insn, int avail_p)
1336 code = GET_CODE (x);
1341 struct reg_avail_info *info = ®_avail_info[REGNO (x)];
1343 if (info->last_bb != current_bb)
1346 return info->last_set < INSN_CUID (insn);
1348 return info->first_set >= INSN_CUID (insn);
1352 if (load_killed_in_block_p (current_bb, INSN_CUID (insn),
1356 return oprs_unchanged_p (XEXP (x, 0), insn, avail_p);
1382 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1386 /* If we are about to do the last recursive call needed at this
1387 level, change it into iteration. This function is called enough
1390 return oprs_unchanged_p (XEXP (x, i), insn, avail_p);
1392 else if (! oprs_unchanged_p (XEXP (x, i), insn, avail_p))
1395 else if (fmt[i] == 'E')
1396 for (j = 0; j < XVECLEN (x, i); j++)
1397 if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p))
1404 /* Used for communication between mems_conflict_for_gcse_p and
1405 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1406 conflict between two memory references. */
1407 static int gcse_mems_conflict_p;
1409 /* Used for communication between mems_conflict_for_gcse_p and
1410 load_killed_in_block_p. A memory reference for a load instruction,
1411 mems_conflict_for_gcse_p will see if a memory store conflicts with
1412 this memory load. */
1413 static rtx gcse_mem_operand;
1415 /* DEST is the output of an instruction. If it is a memory reference, and
1416 possibly conflicts with the load found in gcse_mem_operand, then set
1417 gcse_mems_conflict_p to a nonzero value. */
1420 mems_conflict_for_gcse_p (rtx dest, rtx setter ATTRIBUTE_UNUSED,
1421 void *data ATTRIBUTE_UNUSED)
1423 while (GET_CODE (dest) == SUBREG
1424 || GET_CODE (dest) == ZERO_EXTRACT
1425 || GET_CODE (dest) == SIGN_EXTRACT
1426 || GET_CODE (dest) == STRICT_LOW_PART)
1427 dest = XEXP (dest, 0);
1429 /* If DEST is not a MEM, then it will not conflict with the load. Note
1430 that function calls are assumed to clobber memory, but are handled
1432 if (GET_CODE (dest) != MEM)
1435 /* If we are setting a MEM in our list of specially recognized MEMs,
1436 don't mark as killed this time. */
1438 if (expr_equiv_p (dest, gcse_mem_operand) && pre_ldst_mems != NULL)
1440 if (!find_rtx_in_ldst (dest))
1441 gcse_mems_conflict_p = 1;
1445 if (true_dependence (dest, GET_MODE (dest), gcse_mem_operand,
1447 gcse_mems_conflict_p = 1;
1450 /* Return nonzero if the expression in X (a memory reference) is killed
1451 in block BB before or after the insn with the CUID in UID_LIMIT.
1452 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1455 To check the entire block, set UID_LIMIT to max_uid + 1 and
1459 load_killed_in_block_p (basic_block bb, int uid_limit, rtx x, int avail_p)
1461 rtx list_entry = modify_mem_list[bb->index];
1465 /* Ignore entries in the list that do not apply. */
1467 && INSN_CUID (XEXP (list_entry, 0)) < uid_limit)
1469 && INSN_CUID (XEXP (list_entry, 0)) > uid_limit))
1471 list_entry = XEXP (list_entry, 1);
1475 setter = XEXP (list_entry, 0);
1477 /* If SETTER is a call everything is clobbered. Note that calls
1478 to pure functions are never put on the list, so we need not
1479 worry about them. */
1480 if (GET_CODE (setter) == CALL_INSN)
1483 /* SETTER must be an INSN of some kind that sets memory. Call
1484 note_stores to examine each hunk of memory that is modified.
1486 The note_stores interface is pretty limited, so we have to
1487 communicate via global variables. Yuk. */
1488 gcse_mem_operand = x;
1489 gcse_mems_conflict_p = 0;
1490 note_stores (PATTERN (setter), mems_conflict_for_gcse_p, NULL);
1491 if (gcse_mems_conflict_p)
1493 list_entry = XEXP (list_entry, 1);
1498 /* Return nonzero if the operands of expression X are unchanged from
1499 the start of INSN's basic block up to but not including INSN. */
1502 oprs_anticipatable_p (rtx x, rtx insn)
1504 return oprs_unchanged_p (x, insn, 0);
1507 /* Return nonzero if the operands of expression X are unchanged from
1508 INSN to the end of INSN's basic block. */
1511 oprs_available_p (rtx x, rtx insn)
1513 return oprs_unchanged_p (x, insn, 1);
1516 /* Hash expression X.
1518 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1519 indicating if a volatile operand is found or if the expression contains
1520 something we don't want to insert in the table. HASH_TABLE_SIZE is
1521 the current size of the hash table to be probed.
1523 ??? One might want to merge this with canon_hash. Later. */
1526 hash_expr (rtx x, enum machine_mode mode, int *do_not_record_p,
1527 int hash_table_size)
1531 *do_not_record_p = 0;
1533 hash = hash_expr_1 (x, mode, do_not_record_p);
1534 return hash % hash_table_size;
1537 /* Hash a string. Just add its bytes up. */
1539 static inline unsigned
1540 hash_string_1 (const char *ps)
1543 const unsigned char *p = (const unsigned char *) ps;
1552 /* Subroutine of hash_expr to do the actual work. */
1555 hash_expr_1 (rtx x, enum machine_mode mode, int *do_not_record_p)
1562 /* Used to turn recursion into iteration. We can't rely on GCC's
1563 tail-recursion elimination since we need to keep accumulating values
1570 code = GET_CODE (x);
1574 hash += ((unsigned int) REG << 7) + REGNO (x);
1578 hash += (((unsigned int) CONST_INT << 7) + (unsigned int) mode
1579 + (unsigned int) INTVAL (x));
1583 /* This is like the general case, except that it only counts
1584 the integers representing the constant. */
1585 hash += (unsigned int) code + (unsigned int) GET_MODE (x);
1586 if (GET_MODE (x) != VOIDmode)
1587 for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++)
1588 hash += (unsigned int) XWINT (x, i);
1590 hash += ((unsigned int) CONST_DOUBLE_LOW (x)
1591 + (unsigned int) CONST_DOUBLE_HIGH (x));
1599 units = CONST_VECTOR_NUNITS (x);
1601 for (i = 0; i < units; ++i)
1603 elt = CONST_VECTOR_ELT (x, i);
1604 hash += hash_expr_1 (elt, GET_MODE (elt), do_not_record_p);
1610 /* Assume there is only one rtx object for any given label. */
1612 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1613 differences and differences between each stage's debugging dumps. */
1614 hash += (((unsigned int) LABEL_REF << 7)
1615 + CODE_LABEL_NUMBER (XEXP (x, 0)));
1620 /* Don't hash on the symbol's address to avoid bootstrap differences.
1621 Different hash values may cause expressions to be recorded in
1622 different orders and thus different registers to be used in the
1623 final assembler. This also avoids differences in the dump files
1624 between various stages. */
1626 const unsigned char *p = (const unsigned char *) XSTR (x, 0);
1629 h += (h << 7) + *p++; /* ??? revisit */
1631 hash += ((unsigned int) SYMBOL_REF << 7) + h;
1636 if (MEM_VOLATILE_P (x))
1638 *do_not_record_p = 1;
1642 hash += (unsigned int) MEM;
1643 /* We used alias set for hashing, but this is not good, since the alias
1644 set may differ in -fprofile-arcs and -fbranch-probabilities compilation
1645 causing the profiles to fail to match. */
1656 case UNSPEC_VOLATILE:
1657 *do_not_record_p = 1;
1661 if (MEM_VOLATILE_P (x))
1663 *do_not_record_p = 1;
1668 /* We don't want to take the filename and line into account. */
1669 hash += (unsigned) code + (unsigned) GET_MODE (x)
1670 + hash_string_1 (ASM_OPERANDS_TEMPLATE (x))
1671 + hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x))
1672 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x);
1674 if (ASM_OPERANDS_INPUT_LENGTH (x))
1676 for (i = 1; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
1678 hash += (hash_expr_1 (ASM_OPERANDS_INPUT (x, i),
1679 GET_MODE (ASM_OPERANDS_INPUT (x, i)),
1681 + hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT
1685 hash += hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x, 0));
1686 x = ASM_OPERANDS_INPUT (x, 0);
1687 mode = GET_MODE (x);
1697 hash += (unsigned) code + (unsigned) GET_MODE (x);
1698 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1702 /* If we are about to do the last recursive call
1703 needed at this level, change it into iteration.
1704 This function is called enough to be worth it. */
1711 hash += hash_expr_1 (XEXP (x, i), 0, do_not_record_p);
1712 if (*do_not_record_p)
1716 else if (fmt[i] == 'E')
1717 for (j = 0; j < XVECLEN (x, i); j++)
1719 hash += hash_expr_1 (XVECEXP (x, i, j), 0, do_not_record_p);
1720 if (*do_not_record_p)
1724 else if (fmt[i] == 's')
1725 hash += hash_string_1 (XSTR (x, i));
1726 else if (fmt[i] == 'i')
1727 hash += (unsigned int) XINT (x, i);
1735 /* Hash a set of register REGNO.
1737 Sets are hashed on the register that is set. This simplifies the PRE copy
1740 ??? May need to make things more elaborate. Later, as necessary. */
1743 hash_set (int regno, int hash_table_size)
1748 return hash % hash_table_size;
1751 /* Return nonzero if exp1 is equivalent to exp2.
1752 ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
1755 expr_equiv_p (rtx x, rtx y)
1764 if (x == 0 || y == 0)
1767 code = GET_CODE (x);
1768 if (code != GET_CODE (y))
1771 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
1772 if (GET_MODE (x) != GET_MODE (y))
1783 return XEXP (x, 0) == XEXP (y, 0);
1786 return XSTR (x, 0) == XSTR (y, 0);
1789 return REGNO (x) == REGNO (y);
1792 /* Can't merge two expressions in different alias sets, since we can
1793 decide that the expression is transparent in a block when it isn't,
1794 due to it being set with the different alias set. */
1795 if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
1798 /* A volatile mem should not be considered equivalent to any other. */
1799 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
1803 /* For commutative operations, check both orders. */
1811 return ((expr_equiv_p (XEXP (x, 0), XEXP (y, 0))
1812 && expr_equiv_p (XEXP (x, 1), XEXP (y, 1)))
1813 || (expr_equiv_p (XEXP (x, 0), XEXP (y, 1))
1814 && expr_equiv_p (XEXP (x, 1), XEXP (y, 0))));
1817 /* We don't use the generic code below because we want to
1818 disregard filename and line numbers. */
1820 /* A volatile asm isn't equivalent to any other. */
1821 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
1824 if (GET_MODE (x) != GET_MODE (y)
1825 || strcmp (ASM_OPERANDS_TEMPLATE (x), ASM_OPERANDS_TEMPLATE (y))
1826 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x),
1827 ASM_OPERANDS_OUTPUT_CONSTRAINT (y))
1828 || ASM_OPERANDS_OUTPUT_IDX (x) != ASM_OPERANDS_OUTPUT_IDX (y)
1829 || ASM_OPERANDS_INPUT_LENGTH (x) != ASM_OPERANDS_INPUT_LENGTH (y))
1832 if (ASM_OPERANDS_INPUT_LENGTH (x))
1834 for (i = ASM_OPERANDS_INPUT_LENGTH (x) - 1; i >= 0; i--)
1835 if (! expr_equiv_p (ASM_OPERANDS_INPUT (x, i),
1836 ASM_OPERANDS_INPUT (y, i))
1837 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x, i),
1838 ASM_OPERANDS_INPUT_CONSTRAINT (y, i)))
1848 /* Compare the elements. If any pair of corresponding elements
1849 fail to match, return 0 for the whole thing. */
1851 fmt = GET_RTX_FORMAT (code);
1852 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1857 if (! expr_equiv_p (XEXP (x, i), XEXP (y, i)))
1862 if (XVECLEN (x, i) != XVECLEN (y, i))
1864 for (j = 0; j < XVECLEN (x, i); j++)
1865 if (! expr_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
1870 if (strcmp (XSTR (x, i), XSTR (y, i)))
1875 if (XINT (x, i) != XINT (y, i))
1880 if (XWINT (x, i) != XWINT (y, i))
1895 /* Insert expression X in INSN in the hash TABLE.
1896 If it is already present, record it as the last occurrence in INSN's
1899 MODE is the mode of the value X is being stored into.
1900 It is only used if X is a CONST_INT.
1902 ANTIC_P is nonzero if X is an anticipatable expression.
1903 AVAIL_P is nonzero if X is an available expression. */
1906 insert_expr_in_table (rtx x, enum machine_mode mode, rtx insn, int antic_p,
1907 int avail_p, struct hash_table *table)
1909 int found, do_not_record_p;
1911 struct expr *cur_expr, *last_expr = NULL;
1912 struct occr *antic_occr, *avail_occr;
1913 struct occr *last_occr = NULL;
1915 hash = hash_expr (x, mode, &do_not_record_p, table->size);
1917 /* Do not insert expression in table if it contains volatile operands,
1918 or if hash_expr determines the expression is something we don't want
1919 to or can't handle. */
1920 if (do_not_record_p)
1923 cur_expr = table->table[hash];
1926 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
1928 /* If the expression isn't found, save a pointer to the end of
1930 last_expr = cur_expr;
1931 cur_expr = cur_expr->next_same_hash;
1936 cur_expr = gcse_alloc (sizeof (struct expr));
1937 bytes_used += sizeof (struct expr);
1938 if (table->table[hash] == NULL)
1939 /* This is the first pattern that hashed to this index. */
1940 table->table[hash] = cur_expr;
1942 /* Add EXPR to end of this hash chain. */
1943 last_expr->next_same_hash = cur_expr;
1945 /* Set the fields of the expr element. */
1947 cur_expr->bitmap_index = table->n_elems++;
1948 cur_expr->next_same_hash = NULL;
1949 cur_expr->antic_occr = NULL;
1950 cur_expr->avail_occr = NULL;
1953 /* Now record the occurrence(s). */
1956 antic_occr = cur_expr->antic_occr;
1958 /* Search for another occurrence in the same basic block. */
1959 while (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn))
1961 /* If an occurrence isn't found, save a pointer to the end of
1963 last_occr = antic_occr;
1964 antic_occr = antic_occr->next;
1968 /* Found another instance of the expression in the same basic block.
1969 Prefer the currently recorded one. We want the first one in the
1970 block and the block is scanned from start to end. */
1971 ; /* nothing to do */
1974 /* First occurrence of this expression in this basic block. */
1975 antic_occr = gcse_alloc (sizeof (struct occr));
1976 bytes_used += sizeof (struct occr);
1977 /* First occurrence of this expression in any block? */
1978 if (cur_expr->antic_occr == NULL)
1979 cur_expr->antic_occr = antic_occr;
1981 last_occr->next = antic_occr;
1983 antic_occr->insn = insn;
1984 antic_occr->next = NULL;
1990 avail_occr = cur_expr->avail_occr;
1992 /* Search for another occurrence in the same basic block. */
1993 while (avail_occr && BLOCK_NUM (avail_occr->insn) != BLOCK_NUM (insn))
1995 /* If an occurrence isn't found, save a pointer to the end of
1997 last_occr = avail_occr;
1998 avail_occr = avail_occr->next;
2002 /* Found another instance of the expression in the same basic block.
2003 Prefer this occurrence to the currently recorded one. We want
2004 the last one in the block and the block is scanned from start
2006 avail_occr->insn = insn;
2009 /* First occurrence of this expression in this basic block. */
2010 avail_occr = gcse_alloc (sizeof (struct occr));
2011 bytes_used += sizeof (struct occr);
2013 /* First occurrence of this expression in any block? */
2014 if (cur_expr->avail_occr == NULL)
2015 cur_expr->avail_occr = avail_occr;
2017 last_occr->next = avail_occr;
2019 avail_occr->insn = insn;
2020 avail_occr->next = NULL;
2025 /* Insert pattern X in INSN in the hash table.
2026 X is a SET of a reg to either another reg or a constant.
2027 If it is already present, record it as the last occurrence in INSN's
2031 insert_set_in_table (rtx x, rtx insn, struct hash_table *table)
2035 struct expr *cur_expr, *last_expr = NULL;
2036 struct occr *cur_occr, *last_occr = NULL;
2038 if (GET_CODE (x) != SET
2039 || GET_CODE (SET_DEST (x)) != REG)
2042 hash = hash_set (REGNO (SET_DEST (x)), table->size);
2044 cur_expr = table->table[hash];
2047 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
2049 /* If the expression isn't found, save a pointer to the end of
2051 last_expr = cur_expr;
2052 cur_expr = cur_expr->next_same_hash;
2057 cur_expr = gcse_alloc (sizeof (struct expr));
2058 bytes_used += sizeof (struct expr);
2059 if (table->table[hash] == NULL)
2060 /* This is the first pattern that hashed to this index. */
2061 table->table[hash] = cur_expr;
2063 /* Add EXPR to end of this hash chain. */
2064 last_expr->next_same_hash = cur_expr;
2066 /* Set the fields of the expr element.
2067 We must copy X because it can be modified when copy propagation is
2068 performed on its operands. */
2069 cur_expr->expr = copy_rtx (x);
2070 cur_expr->bitmap_index = table->n_elems++;
2071 cur_expr->next_same_hash = NULL;
2072 cur_expr->antic_occr = NULL;
2073 cur_expr->avail_occr = NULL;
2076 /* Now record the occurrence. */
2077 cur_occr = cur_expr->avail_occr;
2079 /* Search for another occurrence in the same basic block. */
2080 while (cur_occr && BLOCK_NUM (cur_occr->insn) != BLOCK_NUM (insn))
2082 /* If an occurrence isn't found, save a pointer to the end of
2084 last_occr = cur_occr;
2085 cur_occr = cur_occr->next;
2089 /* Found another instance of the expression in the same basic block.
2090 Prefer this occurrence to the currently recorded one. We want the
2091 last one in the block and the block is scanned from start to end. */
2092 cur_occr->insn = insn;
2095 /* First occurrence of this expression in this basic block. */
2096 cur_occr = gcse_alloc (sizeof (struct occr));
2097 bytes_used += sizeof (struct occr);
2099 /* First occurrence of this expression in any block? */
2100 if (cur_expr->avail_occr == NULL)
2101 cur_expr->avail_occr = cur_occr;
2103 last_occr->next = cur_occr;
2105 cur_occr->insn = insn;
2106 cur_occr->next = NULL;
2110 /* Determine whether the rtx X should be treated as a constant for
2111 the purposes of GCSE's constant propagation. */
2114 gcse_constant_p (rtx x)
2116 /* Consider a COMPARE of two integers constant. */
2117 if (GET_CODE (x) == COMPARE
2118 && GET_CODE (XEXP (x, 0)) == CONST_INT
2119 && GET_CODE (XEXP (x, 1)) == CONST_INT)
2123 /* Consider a COMPARE of the same registers is a constant
2124 if they are not floating point registers. */
2125 if (GET_CODE(x) == COMPARE
2126 && GET_CODE (XEXP (x, 0)) == REG
2127 && GET_CODE (XEXP (x, 1)) == REG
2128 && REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 1))
2129 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 0)))
2130 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 1))))
2133 if (GET_CODE (x) == CONSTANT_P_RTX)
2136 return CONSTANT_P (x);
2139 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
2143 hash_scan_set (rtx pat, rtx insn, struct hash_table *table)
2145 rtx src = SET_SRC (pat);
2146 rtx dest = SET_DEST (pat);
2149 if (GET_CODE (src) == CALL)
2150 hash_scan_call (src, insn, table);
2152 else if (GET_CODE (dest) == REG)
2154 unsigned int regno = REGNO (dest);
2157 /* If this is a single set and we are doing constant propagation,
2158 see if a REG_NOTE shows this equivalent to a constant. */
2159 if (table->set_p && (note = find_reg_equal_equiv_note (insn)) != 0
2160 && gcse_constant_p (XEXP (note, 0)))
2161 src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src);
2163 /* Only record sets of pseudo-regs in the hash table. */
2165 && regno >= FIRST_PSEUDO_REGISTER
2166 /* Don't GCSE something if we can't do a reg/reg copy. */
2167 && can_copy_p (GET_MODE (dest))
2168 /* GCSE commonly inserts instruction after the insn. We can't
2169 do that easily for EH_REGION notes so disable GCSE on these
2171 && !find_reg_note (insn, REG_EH_REGION, NULL_RTX)
2172 /* Is SET_SRC something we want to gcse? */
2173 && want_to_gcse_p (src)
2174 /* Don't CSE a nop. */
2175 && ! set_noop_p (pat)
2176 /* Don't GCSE if it has attached REG_EQUIV note.
2177 At this point this only function parameters should have
2178 REG_EQUIV notes and if the argument slot is used somewhere
2179 explicitly, it means address of parameter has been taken,
2180 so we should not extend the lifetime of the pseudo. */
2181 && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
2182 || GET_CODE (XEXP (note, 0)) != MEM))
2184 /* An expression is not anticipatable if its operands are
2185 modified before this insn or if this is not the only SET in
2187 int antic_p = oprs_anticipatable_p (src, insn) && single_set (insn);
2188 /* An expression is not available if its operands are
2189 subsequently modified, including this insn. It's also not
2190 available if this is a branch, because we can't insert
2191 a set after the branch. */
2192 int avail_p = (oprs_available_p (src, insn)
2193 && ! JUMP_P (insn));
2195 insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p, table);
2198 /* Record sets for constant/copy propagation. */
2199 else if (table->set_p
2200 && regno >= FIRST_PSEUDO_REGISTER
2201 && ((GET_CODE (src) == REG
2202 && REGNO (src) >= FIRST_PSEUDO_REGISTER
2203 && can_copy_p (GET_MODE (dest))
2204 && REGNO (src) != regno)
2205 || gcse_constant_p (src))
2206 /* A copy is not available if its src or dest is subsequently
2207 modified. Here we want to search from INSN+1 on, but
2208 oprs_available_p searches from INSN on. */
2209 && (insn == BB_END (BLOCK_FOR_INSN (insn))
2210 || ((tmp = next_nonnote_insn (insn)) != NULL_RTX
2211 && oprs_available_p (pat, tmp))))
2212 insert_set_in_table (pat, insn, table);
2214 /* In case of store we want to consider the memory value as available in
2215 the REG stored in that memory. This makes it possible to remove
2216 redundant loads from due to stores to the same location. */
2217 else if (flag_gcse_las && GET_CODE (src) == REG && GET_CODE (dest) == MEM)
2219 unsigned int regno = REGNO (src);
2221 /* Do not do this for constant/copy propagation. */
2223 /* Only record sets of pseudo-regs in the hash table. */
2224 && regno >= FIRST_PSEUDO_REGISTER
2225 /* Don't GCSE something if we can't do a reg/reg copy. */
2226 && can_copy_p (GET_MODE (src))
2227 /* GCSE commonly inserts instruction after the insn. We can't
2228 do that easily for EH_REGION notes so disable GCSE on these
2230 && ! find_reg_note (insn, REG_EH_REGION, NULL_RTX)
2231 /* Is SET_DEST something we want to gcse? */
2232 && want_to_gcse_p (dest)
2233 /* Don't CSE a nop. */
2234 && ! set_noop_p (pat)
2235 /* Don't GCSE if it has attached REG_EQUIV note.
2236 At this point this only function parameters should have
2237 REG_EQUIV notes and if the argument slot is used somewhere
2238 explicitly, it means address of parameter has been taken,
2239 so we should not extend the lifetime of the pseudo. */
2240 && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
2241 || GET_CODE (XEXP (note, 0)) != MEM))
2243 /* Stores are never anticipatable. */
2245 /* An expression is not available if its operands are
2246 subsequently modified, including this insn. It's also not
2247 available if this is a branch, because we can't insert
2248 a set after the branch. */
2249 int avail_p = oprs_available_p (dest, insn)
2252 /* Record the memory expression (DEST) in the hash table. */
2253 insert_expr_in_table (dest, GET_MODE (dest), insn,
2254 antic_p, avail_p, table);
2260 hash_scan_clobber (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
2261 struct hash_table *table ATTRIBUTE_UNUSED)
2263 /* Currently nothing to do. */
2267 hash_scan_call (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
2268 struct hash_table *table ATTRIBUTE_UNUSED)
2270 /* Currently nothing to do. */
2273 /* Process INSN and add hash table entries as appropriate.
2275 Only available expressions that set a single pseudo-reg are recorded.
2277 Single sets in a PARALLEL could be handled, but it's an extra complication
2278 that isn't dealt with right now. The trick is handling the CLOBBERs that
2279 are also in the PARALLEL. Later.
2281 If SET_P is nonzero, this is for the assignment hash table,
2282 otherwise it is for the expression hash table.
2283 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
2284 not record any expressions. */
2287 hash_scan_insn (rtx insn, struct hash_table *table, int in_libcall_block)
2289 rtx pat = PATTERN (insn);
2292 if (in_libcall_block)
2295 /* Pick out the sets of INSN and for other forms of instructions record
2296 what's been modified. */
2298 if (GET_CODE (pat) == SET)
2299 hash_scan_set (pat, insn, table);
2300 else if (GET_CODE (pat) == PARALLEL)
2301 for (i = 0; i < XVECLEN (pat, 0); i++)
2303 rtx x = XVECEXP (pat, 0, i);
2305 if (GET_CODE (x) == SET)
2306 hash_scan_set (x, insn, table);
2307 else if (GET_CODE (x) == CLOBBER)
2308 hash_scan_clobber (x, insn, table);
2309 else if (GET_CODE (x) == CALL)
2310 hash_scan_call (x, insn, table);
2313 else if (GET_CODE (pat) == CLOBBER)
2314 hash_scan_clobber (pat, insn, table);
2315 else if (GET_CODE (pat) == CALL)
2316 hash_scan_call (pat, insn, table);
2320 dump_hash_table (FILE *file, const char *name, struct hash_table *table)
2323 /* Flattened out table, so it's printed in proper order. */
2324 struct expr **flat_table;
2325 unsigned int *hash_val;
2328 flat_table = xcalloc (table->n_elems, sizeof (struct expr *));
2329 hash_val = xmalloc (table->n_elems * sizeof (unsigned int));
2331 for (i = 0; i < (int) table->size; i++)
2332 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
2334 flat_table[expr->bitmap_index] = expr;
2335 hash_val[expr->bitmap_index] = i;
2338 fprintf (file, "%s hash table (%d buckets, %d entries)\n",
2339 name, table->size, table->n_elems);
2341 for (i = 0; i < (int) table->n_elems; i++)
2342 if (flat_table[i] != 0)
2344 expr = flat_table[i];
2345 fprintf (file, "Index %d (hash value %d)\n ",
2346 expr->bitmap_index, hash_val[i]);
2347 print_rtl (file, expr->expr);
2348 fprintf (file, "\n");
2351 fprintf (file, "\n");
2357 /* Record register first/last/block set information for REGNO in INSN.
2359 first_set records the first place in the block where the register
2360 is set and is used to compute "anticipatability".
2362 last_set records the last place in the block where the register
2363 is set and is used to compute "availability".
2365 last_bb records the block for which first_set and last_set are
2366 valid, as a quick test to invalidate them.
2368 reg_set_in_block records whether the register is set in the block
2369 and is used to compute "transparency". */
2372 record_last_reg_set_info (rtx insn, int regno)
2374 struct reg_avail_info *info = ®_avail_info[regno];
2375 int cuid = INSN_CUID (insn);
2377 info->last_set = cuid;
2378 if (info->last_bb != current_bb)
2380 info->last_bb = current_bb;
2381 info->first_set = cuid;
2382 SET_BIT (reg_set_in_block[current_bb->index], regno);
2387 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
2388 Note we store a pair of elements in the list, so they have to be
2389 taken off pairwise. */
2392 canon_list_insert (rtx dest ATTRIBUTE_UNUSED, rtx unused1 ATTRIBUTE_UNUSED,
2395 rtx dest_addr, insn;
2398 while (GET_CODE (dest) == SUBREG
2399 || GET_CODE (dest) == ZERO_EXTRACT
2400 || GET_CODE (dest) == SIGN_EXTRACT
2401 || GET_CODE (dest) == STRICT_LOW_PART)
2402 dest = XEXP (dest, 0);
2404 /* If DEST is not a MEM, then it will not conflict with a load. Note
2405 that function calls are assumed to clobber memory, but are handled
2408 if (GET_CODE (dest) != MEM)
2411 dest_addr = get_addr (XEXP (dest, 0));
2412 dest_addr = canon_rtx (dest_addr);
2413 insn = (rtx) v_insn;
2414 bb = BLOCK_NUM (insn);
2416 canon_modify_mem_list[bb] =
2417 alloc_EXPR_LIST (VOIDmode, dest_addr, canon_modify_mem_list[bb]);
2418 canon_modify_mem_list[bb] =
2419 alloc_EXPR_LIST (VOIDmode, dest, canon_modify_mem_list[bb]);
2420 bitmap_set_bit (canon_modify_mem_list_set, bb);
2423 /* Record memory modification information for INSN. We do not actually care
2424 about the memory location(s) that are set, or even how they are set (consider
2425 a CALL_INSN). We merely need to record which insns modify memory. */
2428 record_last_mem_set_info (rtx 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 (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
2457 rtx last_set_insn = (rtx) data;
2459 if (GET_CODE (dest) == SUBREG)
2460 dest = SUBREG_REG (dest);
2462 if (GET_CODE (dest) == REG)
2463 record_last_reg_set_info (last_set_insn, REGNO (dest));
2464 else if (GET_CODE (dest) == MEM
2465 /* Ignore pushes, they clobber nothing. */
2466 && ! push_operand (dest, GET_MODE (dest)))
2467 record_last_mem_set_info (last_set_insn);
2470 /* Top level function to create an expression or assignment hash table.
2472 Expression entries are placed in the hash table if
2473 - they are of the form (set (pseudo-reg) src),
2474 - src is something we want to perform GCSE on,
2475 - none of the operands are subsequently modified in the block
2477 Assignment entries are placed in the hash table if
2478 - they are of the form (set (pseudo-reg) src),
2479 - src is something we want to perform const/copy propagation on,
2480 - none of the operands or target are subsequently modified in the block
2482 Currently src must be a pseudo-reg or a const_int.
2484 TABLE is the table computed. */
2487 compute_hash_table_work (struct hash_table *table)
2491 /* While we compute the hash table we also compute a bit array of which
2492 registers are set in which blocks.
2493 ??? This isn't needed during const/copy propagation, but it's cheap to
2495 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
2497 /* re-Cache any INSN_LIST nodes we have allocated. */
2498 clear_modify_mem_tables ();
2499 /* Some working arrays used to track first and last set in each block. */
2500 reg_avail_info = gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
2502 for (i = 0; i < max_gcse_regno; ++i)
2503 reg_avail_info[i].last_bb = NULL;
2505 FOR_EACH_BB (current_bb)
2509 int in_libcall_block;
2511 /* First pass over the instructions records information used to
2512 determine when registers and memory are first and last set.
2513 ??? hard-reg reg_set_in_block computation
2514 could be moved to compute_sets since they currently don't change. */
2516 for (insn = BB_HEAD (current_bb);
2517 insn && insn != NEXT_INSN (BB_END (current_bb));
2518 insn = NEXT_INSN (insn))
2520 if (! INSN_P (insn))
2523 if (GET_CODE (insn) == CALL_INSN)
2525 bool clobbers_all = false;
2526 #ifdef NON_SAVING_SETJMP
2527 if (NON_SAVING_SETJMP
2528 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
2529 clobbers_all = true;
2532 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2534 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2535 record_last_reg_set_info (insn, regno);
2540 note_stores (PATTERN (insn), record_last_set_info, insn);
2543 /* Insert implicit sets in the hash table. */
2545 && implicit_sets[current_bb->index] != NULL_RTX)
2546 hash_scan_set (implicit_sets[current_bb->index],
2547 BB_HEAD (current_bb), table);
2549 /* The next pass builds the hash table. */
2551 for (insn = BB_HEAD (current_bb), in_libcall_block = 0;
2552 insn && insn != NEXT_INSN (BB_END (current_bb));
2553 insn = NEXT_INSN (insn))
2556 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2557 in_libcall_block = 1;
2558 else if (table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2559 in_libcall_block = 0;
2560 hash_scan_insn (insn, table, in_libcall_block);
2561 if (!table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2562 in_libcall_block = 0;
2566 free (reg_avail_info);
2567 reg_avail_info = NULL;
2570 /* Allocate space for the set/expr hash TABLE.
2571 N_INSNS is the number of instructions in the function.
2572 It is used to determine the number of buckets to use.
2573 SET_P determines whether set or expression table will
2577 alloc_hash_table (int n_insns, struct hash_table *table, int set_p)
2581 table->size = n_insns / 4;
2582 if (table->size < 11)
2585 /* Attempt to maintain efficient use of hash table.
2586 Making it an odd number is simplest for now.
2587 ??? Later take some measurements. */
2589 n = table->size * sizeof (struct expr *);
2590 table->table = gmalloc (n);
2591 table->set_p = set_p;
2594 /* Free things allocated by alloc_hash_table. */
2597 free_hash_table (struct hash_table *table)
2599 free (table->table);
2602 /* Compute the hash TABLE for doing copy/const propagation or
2603 expression hash table. */
2606 compute_hash_table (struct hash_table *table)
2608 /* Initialize count of number of entries in hash table. */
2610 memset (table->table, 0, table->size * sizeof (struct expr *));
2612 compute_hash_table_work (table);
2615 /* Expression tracking support. */
2617 /* Lookup pattern PAT in the expression TABLE.
2618 The result is a pointer to the table entry, or NULL if not found. */
2620 static struct expr *
2621 lookup_expr (rtx pat, struct hash_table *table)
2623 int do_not_record_p;
2624 unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p,
2628 if (do_not_record_p)
2631 expr = table->table[hash];
2633 while (expr && ! expr_equiv_p (expr->expr, pat))
2634 expr = expr->next_same_hash;
2639 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2640 table entry, or NULL if not found. */
2642 static struct expr *
2643 lookup_set (unsigned int regno, struct hash_table *table)
2645 unsigned int hash = hash_set (regno, table->size);
2648 expr = table->table[hash];
2650 while (expr && REGNO (SET_DEST (expr->expr)) != regno)
2651 expr = expr->next_same_hash;
2656 /* Return the next entry for REGNO in list EXPR. */
2658 static struct expr *
2659 next_set (unsigned int regno, struct expr *expr)
2662 expr = expr->next_same_hash;
2663 while (expr && REGNO (SET_DEST (expr->expr)) != regno);
2668 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2669 types may be mixed. */
2672 free_insn_expr_list_list (rtx *listp)
2676 for (list = *listp; list ; list = next)
2678 next = XEXP (list, 1);
2679 if (GET_CODE (list) == EXPR_LIST)
2680 free_EXPR_LIST_node (list);
2682 free_INSN_LIST_node (list);
2688 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2690 clear_modify_mem_tables (void)
2694 EXECUTE_IF_SET_IN_BITMAP
2695 (modify_mem_list_set, 0, i, free_INSN_LIST_list (modify_mem_list + i));
2696 bitmap_clear (modify_mem_list_set);
2698 EXECUTE_IF_SET_IN_BITMAP
2699 (canon_modify_mem_list_set, 0, i,
2700 free_insn_expr_list_list (canon_modify_mem_list + i));
2701 bitmap_clear (canon_modify_mem_list_set);
2704 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2707 free_modify_mem_tables (void)
2709 clear_modify_mem_tables ();
2710 free (modify_mem_list);
2711 free (canon_modify_mem_list);
2712 modify_mem_list = 0;
2713 canon_modify_mem_list = 0;
2716 /* Reset tables used to keep track of what's still available [since the
2717 start of the block]. */
2720 reset_opr_set_tables (void)
2722 /* Maintain a bitmap of which regs have been set since beginning of
2724 CLEAR_REG_SET (reg_set_bitmap);
2726 /* Also keep a record of the last instruction to modify memory.
2727 For now this is very trivial, we only record whether any memory
2728 location has been modified. */
2729 clear_modify_mem_tables ();
2732 /* Return nonzero if the operands of X are not set before INSN in
2733 INSN's basic block. */
2736 oprs_not_set_p (rtx x, rtx insn)
2745 code = GET_CODE (x);
2761 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn),
2762 INSN_CUID (insn), x, 0))
2765 return oprs_not_set_p (XEXP (x, 0), insn);
2768 return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x));
2774 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2778 /* If we are about to do the last recursive call
2779 needed at this level, change it into iteration.
2780 This function is called enough to be worth it. */
2782 return oprs_not_set_p (XEXP (x, i), insn);
2784 if (! oprs_not_set_p (XEXP (x, i), insn))
2787 else if (fmt[i] == 'E')
2788 for (j = 0; j < XVECLEN (x, i); j++)
2789 if (! oprs_not_set_p (XVECEXP (x, i, j), insn))
2796 /* Mark things set by a CALL. */
2799 mark_call (rtx insn)
2801 if (! CONST_OR_PURE_CALL_P (insn))
2802 record_last_mem_set_info (insn);
2805 /* Mark things set by a SET. */
2808 mark_set (rtx pat, rtx insn)
2810 rtx dest = SET_DEST (pat);
2812 while (GET_CODE (dest) == SUBREG
2813 || GET_CODE (dest) == ZERO_EXTRACT
2814 || GET_CODE (dest) == SIGN_EXTRACT
2815 || GET_CODE (dest) == STRICT_LOW_PART)
2816 dest = XEXP (dest, 0);
2818 if (GET_CODE (dest) == REG)
2819 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (dest));
2820 else if (GET_CODE (dest) == MEM)
2821 record_last_mem_set_info (insn);
2823 if (GET_CODE (SET_SRC (pat)) == CALL)
2827 /* Record things set by a CLOBBER. */
2830 mark_clobber (rtx pat, rtx insn)
2832 rtx clob = XEXP (pat, 0);
2834 while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART)
2835 clob = XEXP (clob, 0);
2837 if (GET_CODE (clob) == REG)
2838 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (clob));
2840 record_last_mem_set_info (insn);
2843 /* Record things set by INSN.
2844 This data is used by oprs_not_set_p. */
2847 mark_oprs_set (rtx insn)
2849 rtx pat = PATTERN (insn);
2852 if (GET_CODE (pat) == SET)
2853 mark_set (pat, insn);
2854 else if (GET_CODE (pat) == PARALLEL)
2855 for (i = 0; i < XVECLEN (pat, 0); i++)
2857 rtx x = XVECEXP (pat, 0, i);
2859 if (GET_CODE (x) == SET)
2861 else if (GET_CODE (x) == CLOBBER)
2862 mark_clobber (x, insn);
2863 else if (GET_CODE (x) == CALL)
2867 else if (GET_CODE (pat) == CLOBBER)
2868 mark_clobber (pat, insn);
2869 else if (GET_CODE (pat) == CALL)
2874 /* Classic GCSE reaching definition support. */
2876 /* Allocate reaching def variables. */
2879 alloc_rd_mem (int n_blocks, int n_insns)
2881 rd_kill = sbitmap_vector_alloc (n_blocks, n_insns);
2882 sbitmap_vector_zero (rd_kill, n_blocks);
2884 rd_gen = sbitmap_vector_alloc (n_blocks, n_insns);
2885 sbitmap_vector_zero (rd_gen, n_blocks);
2887 reaching_defs = sbitmap_vector_alloc (n_blocks, n_insns);
2888 sbitmap_vector_zero (reaching_defs, n_blocks);
2890 rd_out = sbitmap_vector_alloc (n_blocks, n_insns);
2891 sbitmap_vector_zero (rd_out, n_blocks);
2894 /* Free reaching def variables. */
2899 sbitmap_vector_free (rd_kill);
2900 sbitmap_vector_free (rd_gen);
2901 sbitmap_vector_free (reaching_defs);
2902 sbitmap_vector_free (rd_out);
2905 /* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
2908 handle_rd_kill_set (rtx insn, int regno, basic_block bb)
2910 struct reg_set *this_reg;
2912 for (this_reg = reg_set_table[regno]; this_reg; this_reg = this_reg ->next)
2913 if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn))
2914 SET_BIT (rd_kill[bb->index], INSN_CUID (this_reg->insn));
2917 /* Compute the set of kill's for reaching definitions. */
2920 compute_kill_rd (void)
2928 For each set bit in `gen' of the block (i.e each insn which
2929 generates a definition in the block)
2930 Call the reg set by the insn corresponding to that bit regx
2931 Look at the linked list starting at reg_set_table[regx]
2932 For each setting of regx in the linked list, which is not in
2934 Set the bit in `kill' corresponding to that insn. */
2936 for (cuid = 0; cuid < max_cuid; cuid++)
2937 if (TEST_BIT (rd_gen[bb->index], cuid))
2939 rtx insn = CUID_INSN (cuid);
2940 rtx pat = PATTERN (insn);
2942 if (GET_CODE (insn) == CALL_INSN)
2944 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2945 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2946 handle_rd_kill_set (insn, regno, bb);
2949 if (GET_CODE (pat) == PARALLEL)
2951 for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
2953 enum rtx_code code = GET_CODE (XVECEXP (pat, 0, i));
2955 if ((code == SET || code == CLOBBER)
2956 && GET_CODE (XEXP (XVECEXP (pat, 0, i), 0)) == REG)
2957 handle_rd_kill_set (insn,
2958 REGNO (XEXP (XVECEXP (pat, 0, i), 0)),
2962 else if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == REG)
2963 /* Each setting of this register outside of this block
2964 must be marked in the set of kills in this block. */
2965 handle_rd_kill_set (insn, REGNO (SET_DEST (pat)), bb);
2969 /* Compute the reaching definitions as in
2970 Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
2971 Chapter 10. It is the same algorithm as used for computing available
2972 expressions but applied to the gens and kills of reaching definitions. */
2977 int changed, passes;
2981 sbitmap_copy (rd_out[bb->index] /*dst*/, rd_gen[bb->index] /*src*/);
2990 sbitmap_union_of_preds (reaching_defs[bb->index], rd_out, bb->index);
2991 changed |= sbitmap_union_of_diff_cg (rd_out[bb->index], rd_gen[bb->index],
2992 reaching_defs[bb->index], rd_kill[bb->index]);
2998 fprintf (gcse_file, "reaching def computation: %d passes\n", passes);
3001 /* Classic GCSE available expression support. */
3003 /* Allocate memory for available expression computation. */
3006 alloc_avail_expr_mem (int n_blocks, int n_exprs)
3008 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
3009 sbitmap_vector_zero (ae_kill, n_blocks);
3011 ae_gen = sbitmap_vector_alloc (n_blocks, n_exprs);
3012 sbitmap_vector_zero (ae_gen, n_blocks);
3014 ae_in = sbitmap_vector_alloc (n_blocks, n_exprs);
3015 sbitmap_vector_zero (ae_in, n_blocks);
3017 ae_out = sbitmap_vector_alloc (n_blocks, n_exprs);
3018 sbitmap_vector_zero (ae_out, n_blocks);
3022 free_avail_expr_mem (void)
3024 sbitmap_vector_free (ae_kill);
3025 sbitmap_vector_free (ae_gen);
3026 sbitmap_vector_free (ae_in);
3027 sbitmap_vector_free (ae_out);
3030 /* Compute the set of available expressions generated in each basic block. */
3033 compute_ae_gen (struct hash_table *expr_hash_table)
3039 /* For each recorded occurrence of each expression, set ae_gen[bb][expr].
3040 This is all we have to do because an expression is not recorded if it
3041 is not available, and the only expressions we want to work with are the
3042 ones that are recorded. */
3043 for (i = 0; i < expr_hash_table->size; i++)
3044 for (expr = expr_hash_table->table[i]; expr != 0; expr = expr->next_same_hash)
3045 for (occr = expr->avail_occr; occr != 0; occr = occr->next)
3046 SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index);
3049 /* Return nonzero if expression X is killed in BB. */
3052 expr_killed_p (rtx x, basic_block bb)
3061 code = GET_CODE (x);
3065 return TEST_BIT (reg_set_in_block[bb->index], REGNO (x));
3068 if (load_killed_in_block_p (bb, get_max_uid () + 1, x, 0))
3071 return expr_killed_p (XEXP (x, 0), bb);
3089 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3093 /* If we are about to do the last recursive call
3094 needed at this level, change it into iteration.
3095 This function is called enough to be worth it. */
3097 return expr_killed_p (XEXP (x, i), bb);
3098 else if (expr_killed_p (XEXP (x, i), bb))
3101 else if (fmt[i] == 'E')
3102 for (j = 0; j < XVECLEN (x, i); j++)
3103 if (expr_killed_p (XVECEXP (x, i, j), bb))
3110 /* Compute the set of available expressions killed in each basic block. */
3113 compute_ae_kill (sbitmap *ae_gen, sbitmap *ae_kill,
3114 struct hash_table *expr_hash_table)
3121 for (i = 0; i < expr_hash_table->size; i++)
3122 for (expr = expr_hash_table->table[i]; expr; expr = expr->next_same_hash)
3124 /* Skip EXPR if generated in this block. */
3125 if (TEST_BIT (ae_gen[bb->index], expr->bitmap_index))
3128 if (expr_killed_p (expr->expr, bb))
3129 SET_BIT (ae_kill[bb->index], expr->bitmap_index);
3133 /* Actually perform the Classic GCSE optimizations. */
3135 /* Return nonzero if occurrence OCCR of expression EXPR reaches block BB.
3137 CHECK_SELF_LOOP is nonzero if we should consider a block reaching itself
3138 as a positive reach. We want to do this when there are two computations
3139 of the expression in the block.
3141 VISITED is a pointer to a working buffer for tracking which BB's have
3142 been visited. It is NULL for the top-level call.
3144 We treat reaching expressions that go through blocks containing the same
3145 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3146 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3147 2 as not reaching. The intent is to improve the probability of finding
3148 only one reaching expression and to reduce register lifetimes by picking
3149 the closest such expression. */
3152 expr_reaches_here_p_work (struct occr *occr, struct expr *expr,
3153 basic_block bb, int check_self_loop, char *visited)
3157 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
3159 basic_block pred_bb = pred->src;
3161 if (visited[pred_bb->index])
3162 /* This predecessor has already been visited. Nothing to do. */
3164 else if (pred_bb == bb)
3166 /* BB loops on itself. */
3168 && TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index)
3169 && BLOCK_NUM (occr->insn) == pred_bb->index)
3172 visited[pred_bb->index] = 1;
3175 /* Ignore this predecessor if it kills the expression. */
3176 else if (TEST_BIT (ae_kill[pred_bb->index], expr->bitmap_index))
3177 visited[pred_bb->index] = 1;
3179 /* Does this predecessor generate this expression? */
3180 else if (TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index))
3182 /* Is this the occurrence we're looking for?
3183 Note that there's only one generating occurrence per block
3184 so we just need to check the block number. */
3185 if (BLOCK_NUM (occr->insn) == pred_bb->index)
3188 visited[pred_bb->index] = 1;
3191 /* Neither gen nor kill. */
3194 visited[pred_bb->index] = 1;
3195 if (expr_reaches_here_p_work (occr, expr, pred_bb, check_self_loop,
3202 /* All paths have been checked. */
3206 /* This wrapper for expr_reaches_here_p_work() is to ensure that any
3207 memory allocated for that function is returned. */
3210 expr_reaches_here_p (struct occr *occr, struct expr *expr, basic_block bb,
3211 int check_self_loop)
3214 char *visited = xcalloc (last_basic_block, 1);
3216 rval = expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited);
3222 /* Return the instruction that computes EXPR that reaches INSN's basic block.
3223 If there is more than one such instruction, return NULL.
3225 Called only by handle_avail_expr. */
3228 computing_insn (struct expr *expr, rtx insn)
3230 basic_block bb = BLOCK_FOR_INSN (insn);
3232 if (expr->avail_occr->next == NULL)
3234 if (BLOCK_FOR_INSN (expr->avail_occr->insn) == bb)
3235 /* The available expression is actually itself
3236 (i.e. a loop in the flow graph) so do nothing. */
3239 /* (FIXME) Case that we found a pattern that was created by
3240 a substitution that took place. */
3241 return expr->avail_occr->insn;
3245 /* Pattern is computed more than once.
3246 Search backwards from this insn to see how many of these
3247 computations actually reach this insn. */
3249 rtx insn_computes_expr = NULL;
3252 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
3254 if (BLOCK_FOR_INSN (occr->insn) == bb)
3256 /* The expression is generated in this block.
3257 The only time we care about this is when the expression
3258 is generated later in the block [and thus there's a loop].
3259 We let the normal cse pass handle the other cases. */
3260 if (INSN_CUID (insn) < INSN_CUID (occr->insn)
3261 && expr_reaches_here_p (occr, expr, bb, 1))
3267 insn_computes_expr = occr->insn;
3270 else if (expr_reaches_here_p (occr, expr, bb, 0))
3276 insn_computes_expr = occr->insn;
3280 if (insn_computes_expr == NULL)
3283 return insn_computes_expr;
3287 /* Return nonzero if the definition in DEF_INSN can reach INSN.
3288 Only called by can_disregard_other_sets. */
3291 def_reaches_here_p (rtx insn, rtx def_insn)
3295 if (TEST_BIT (reaching_defs[BLOCK_NUM (insn)], INSN_CUID (def_insn)))
3298 if (BLOCK_NUM (insn) == BLOCK_NUM (def_insn))
3300 if (INSN_CUID (def_insn) < INSN_CUID (insn))
3302 if (GET_CODE (PATTERN (def_insn)) == PARALLEL)
3304 else if (GET_CODE (PATTERN (def_insn)) == CLOBBER)
3305 reg = XEXP (PATTERN (def_insn), 0);
3306 else if (GET_CODE (PATTERN (def_insn)) == SET)
3307 reg = SET_DEST (PATTERN (def_insn));
3311 return ! reg_set_between_p (reg, NEXT_INSN (def_insn), insn);
3320 /* Return nonzero if *ADDR_THIS_REG can only have one value at INSN. The
3321 value returned is the number of definitions that reach INSN. Returning a
3322 value of zero means that [maybe] more than one definition reaches INSN and
3323 the caller can't perform whatever optimization it is trying. i.e. it is
3324 always safe to return zero. */
3327 can_disregard_other_sets (struct reg_set **addr_this_reg, rtx insn, int for_combine)
3329 int number_of_reaching_defs = 0;
3330 struct reg_set *this_reg;
3332 for (this_reg = *addr_this_reg; this_reg != 0; this_reg = this_reg->next)
3333 if (def_reaches_here_p (insn, this_reg->insn))
3335 number_of_reaching_defs++;
3336 /* Ignore parallels for now. */
3337 if (GET_CODE (PATTERN (this_reg->insn)) == PARALLEL)
3341 && (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER
3342 || ! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
3343 SET_SRC (PATTERN (insn)))))
3344 /* A setting of the reg to a different value reaches INSN. */
3347 if (number_of_reaching_defs > 1)
3349 /* If in this setting the value the register is being set to is
3350 equal to the previous value the register was set to and this
3351 setting reaches the insn we are trying to do the substitution
3352 on then we are ok. */
3353 if (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER)
3355 else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
3356 SET_SRC (PATTERN (insn))))
3360 *addr_this_reg = this_reg;
3363 return number_of_reaching_defs;
3366 /* Expression computed by insn is available and the substitution is legal,
3367 so try to perform the substitution.
3369 The result is nonzero if any changes were made. */
3372 handle_avail_expr (rtx insn, struct expr *expr)
3374 rtx pat, insn_computes_expr, expr_set;
3376 struct reg_set *this_reg;
3377 int found_setting, use_src;
3380 /* We only handle the case where one computation of the expression
3381 reaches this instruction. */
3382 insn_computes_expr = computing_insn (expr, insn);
3383 if (insn_computes_expr == NULL)
3385 expr_set = single_set (insn_computes_expr);
3392 /* At this point we know only one computation of EXPR outside of this
3393 block reaches this insn. Now try to find a register that the
3394 expression is computed into. */
3395 if (GET_CODE (SET_SRC (expr_set)) == REG)
3397 /* This is the case when the available expression that reaches
3398 here has already been handled as an available expression. */
3399 unsigned int regnum_for_replacing
3400 = REGNO (SET_SRC (expr_set));
3402 /* If the register was created by GCSE we can't use `reg_set_table',
3403 however we know it's set only once. */
3404 if (regnum_for_replacing >= max_gcse_regno
3405 /* If the register the expression is computed into is set only once,
3406 or only one set reaches this insn, we can use it. */
3407 || (((this_reg = reg_set_table[regnum_for_replacing]),
3408 this_reg->next == NULL)
3409 || can_disregard_other_sets (&this_reg, insn, 0)))
3418 unsigned int regnum_for_replacing
3419 = REGNO (SET_DEST (expr_set));
3421 /* This shouldn't happen. */
3422 if (regnum_for_replacing >= max_gcse_regno)
3425 this_reg = reg_set_table[regnum_for_replacing];
3427 /* If the register the expression is computed into is set only once,
3428 or only one set reaches this insn, use it. */
3429 if (this_reg->next == NULL
3430 || can_disregard_other_sets (&this_reg, insn, 0))
3436 pat = PATTERN (insn);
3438 to = SET_SRC (expr_set);
3440 to = SET_DEST (expr_set);
3441 changed = validate_change (insn, &SET_SRC (pat), to, 0);
3443 /* We should be able to ignore the return code from validate_change but
3444 to play it safe we check. */
3448 if (gcse_file != NULL)
3450 fprintf (gcse_file, "GCSE: Replacing the source in insn %d with",
3452 fprintf (gcse_file, " reg %d %s insn %d\n",
3453 REGNO (to), use_src ? "from" : "set in",
3454 INSN_UID (insn_computes_expr));
3459 /* The register that the expr is computed into is set more than once. */
3460 else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
3462 /* Insert an insn after insnx that copies the reg set in insnx
3463 into a new pseudo register call this new register REGN.
3464 From insnb until end of basic block or until REGB is set
3465 replace all uses of REGB with REGN. */
3468 to = gen_reg_rtx (GET_MODE (SET_DEST (expr_set)));
3470 /* Generate the new insn. */
3471 /* ??? If the change fails, we return 0, even though we created
3472 an insn. I think this is ok. */
3474 = emit_insn_after (gen_rtx_SET (VOIDmode, to,
3475 SET_DEST (expr_set)),
3476 insn_computes_expr);
3478 /* Keep register set table up to date. */
3479 record_one_set (REGNO (to), new_insn);
3481 gcse_create_count++;
3482 if (gcse_file != NULL)
3484 fprintf (gcse_file, "GCSE: Creating insn %d to copy value of reg %d",
3485 INSN_UID (NEXT_INSN (insn_computes_expr)),
3486 REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr)))));
3487 fprintf (gcse_file, ", computed in insn %d,\n",
3488 INSN_UID (insn_computes_expr));
3489 fprintf (gcse_file, " into newly allocated reg %d\n",
3493 pat = PATTERN (insn);
3495 /* Do register replacement for INSN. */
3496 changed = validate_change (insn, &SET_SRC (pat),
3498 (NEXT_INSN (insn_computes_expr))),
3501 /* We should be able to ignore the return code from validate_change but
3502 to play it safe we check. */
3506 if (gcse_file != NULL)
3509 "GCSE: Replacing the source in insn %d with reg %d ",
3511 REGNO (SET_DEST (PATTERN (NEXT_INSN
3512 (insn_computes_expr)))));
3513 fprintf (gcse_file, "set in insn %d\n",
3514 INSN_UID (insn_computes_expr));
3522 /* Perform classic GCSE. This is called by one_classic_gcse_pass after all
3523 the dataflow analysis has been done.
3525 The result is nonzero if a change was made. */
3534 /* Note we start at block 1. */
3536 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
3540 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
3542 /* Reset tables used to keep track of what's still valid [since the
3543 start of the block]. */
3544 reset_opr_set_tables ();
3546 for (insn = BB_HEAD (bb);
3547 insn != NULL && insn != NEXT_INSN (BB_END (bb));
3548 insn = NEXT_INSN (insn))
3550 /* Is insn of form (set (pseudo-reg) ...)? */
3551 if (GET_CODE (insn) == INSN
3552 && GET_CODE (PATTERN (insn)) == SET
3553 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
3554 && REGNO (SET_DEST (PATTERN (insn))) >= FIRST_PSEUDO_REGISTER)
3556 rtx pat = PATTERN (insn);
3557 rtx src = SET_SRC (pat);
3560 if (want_to_gcse_p (src)
3561 /* Is the expression recorded? */
3562 && ((expr = lookup_expr (src, &expr_hash_table)) != NULL)
3563 /* Is the expression available [at the start of the
3565 && TEST_BIT (ae_in[bb->index], expr->bitmap_index)
3566 /* Are the operands unchanged since the start of the
3568 && oprs_not_set_p (src, insn))
3569 changed |= handle_avail_expr (insn, expr);
3572 /* Keep track of everything modified by this insn. */
3573 /* ??? Need to be careful w.r.t. mods done to INSN. */
3575 mark_oprs_set (insn);
3582 /* Top level routine to perform one classic GCSE pass.
3584 Return nonzero if a change was made. */
3587 one_classic_gcse_pass (int pass)
3591 gcse_subst_count = 0;
3592 gcse_create_count = 0;
3594 alloc_hash_table (max_cuid, &expr_hash_table, 0);
3595 alloc_rd_mem (last_basic_block, max_cuid);
3596 compute_hash_table (&expr_hash_table);
3598 dump_hash_table (gcse_file, "Expression", &expr_hash_table);
3600 if (expr_hash_table.n_elems > 0)
3604 alloc_avail_expr_mem (last_basic_block, expr_hash_table.n_elems);
3605 compute_ae_gen (&expr_hash_table);
3606 compute_ae_kill (ae_gen, ae_kill, &expr_hash_table);
3607 compute_available (ae_gen, ae_kill, ae_out, ae_in);
3608 changed = classic_gcse ();
3609 free_avail_expr_mem ();
3613 free_hash_table (&expr_hash_table);
3617 fprintf (gcse_file, "\n");
3618 fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
3619 (*lang_hooks.decl_printable_name) (current_function_decl, 2),
3620 pass, bytes_used, gcse_subst_count);
3621 fprintf (gcse_file, "%d insns created\n", gcse_create_count);
3627 /* Compute copy/constant propagation working variables. */
3629 /* Local properties of assignments. */
3630 static sbitmap *cprop_pavloc;
3631 static sbitmap *cprop_absaltered;
3633 /* Global properties of assignments (computed from the local properties). */
3634 static sbitmap *cprop_avin;
3635 static sbitmap *cprop_avout;
3637 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
3638 basic blocks. N_SETS is the number of sets. */
3641 alloc_cprop_mem (int n_blocks, int n_sets)
3643 cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
3644 cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
3646 cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
3647 cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
3650 /* Free vars used by copy/const propagation. */
3653 free_cprop_mem (void)
3655 sbitmap_vector_free (cprop_pavloc);
3656 sbitmap_vector_free (cprop_absaltered);
3657 sbitmap_vector_free (cprop_avin);
3658 sbitmap_vector_free (cprop_avout);
3661 /* For each block, compute whether X is transparent. X is either an
3662 expression or an assignment [though we don't care which, for this context
3663 an assignment is treated as an expression]. For each block where an
3664 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
3668 compute_transp (rtx x, int indx, sbitmap *bmap, int set_p)
3676 /* repeat is used to turn tail-recursion into iteration since GCC
3677 can't do it when there's no return value. */
3683 code = GET_CODE (x);
3689 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
3692 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
3693 SET_BIT (bmap[bb->index], indx);
3697 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
3698 SET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
3703 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
3706 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
3707 RESET_BIT (bmap[bb->index], indx);
3711 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
3712 RESET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
3721 rtx list_entry = canon_modify_mem_list[bb->index];
3725 rtx dest, dest_addr;
3727 if (GET_CODE (XEXP (list_entry, 0)) == CALL_INSN)
3730 SET_BIT (bmap[bb->index], indx);
3732 RESET_BIT (bmap[bb->index], indx);
3735 /* LIST_ENTRY must be an INSN of some kind that sets memory.
3736 Examine each hunk of memory that is modified. */
3738 dest = XEXP (list_entry, 0);
3739 list_entry = XEXP (list_entry, 1);
3740 dest_addr = XEXP (list_entry, 0);
3742 if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
3743 x, rtx_addr_varies_p))
3746 SET_BIT (bmap[bb->index], indx);
3748 RESET_BIT (bmap[bb->index], indx);
3751 list_entry = XEXP (list_entry, 1);
3774 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3778 /* If we are about to do the last recursive call
3779 needed at this level, change it into iteration.
3780 This function is called enough to be worth it. */
3787 compute_transp (XEXP (x, i), indx, bmap, set_p);
3789 else if (fmt[i] == 'E')
3790 for (j = 0; j < XVECLEN (x, i); j++)
3791 compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
3795 /* Top level routine to do the dataflow analysis needed by copy/const
3799 compute_cprop_data (void)
3801 compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, &set_hash_table);
3802 compute_available (cprop_pavloc, cprop_absaltered,
3803 cprop_avout, cprop_avin);
3806 /* Copy/constant propagation. */
3808 /* Maximum number of register uses in an insn that we handle. */
3811 /* Table of uses found in an insn.
3812 Allocated statically to avoid alloc/free complexity and overhead. */
3813 static struct reg_use reg_use_table[MAX_USES];
3815 /* Index into `reg_use_table' while building it. */
3816 static int reg_use_count;
3818 /* Set up a list of register numbers used in INSN. The found uses are stored
3819 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
3820 and contains the number of uses in the table upon exit.
3822 ??? If a register appears multiple times we will record it multiple times.
3823 This doesn't hurt anything but it will slow things down. */
3826 find_used_regs (rtx *xptr, void *data ATTRIBUTE_UNUSED)
3833 /* repeat is used to turn tail-recursion into iteration since GCC
3834 can't do it when there's no return value. */
3839 code = GET_CODE (x);
3842 if (reg_use_count == MAX_USES)
3845 reg_use_table[reg_use_count].reg_rtx = x;
3849 /* Recursively scan the operands of this expression. */
3851 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3855 /* If we are about to do the last recursive call
3856 needed at this level, change it into iteration.
3857 This function is called enough to be worth it. */
3864 find_used_regs (&XEXP (x, i), data);
3866 else if (fmt[i] == 'E')
3867 for (j = 0; j < XVECLEN (x, i); j++)
3868 find_used_regs (&XVECEXP (x, i, j), data);
3872 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
3873 Returns nonzero is successful. */
3876 try_replace_reg (rtx from, rtx to, rtx insn)
3878 rtx note = find_reg_equal_equiv_note (insn);
3881 rtx set = single_set (insn);
3883 validate_replace_src_group (from, to, insn);
3884 if (num_changes_pending () && apply_change_group ())
3887 /* Try to simplify SET_SRC if we have substituted a constant. */
3888 if (success && set && CONSTANT_P (to))
3890 src = simplify_rtx (SET_SRC (set));
3893 validate_change (insn, &SET_SRC (set), src, 0);
3896 /* If there is already a NOTE, update the expression in it with our
3899 XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to);
3901 if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
3903 /* If above failed and this is a single set, try to simplify the source of
3904 the set given our substitution. We could perhaps try this for multiple
3905 SETs, but it probably won't buy us anything. */
3906 src = simplify_replace_rtx (SET_SRC (set), from, to);
3908 if (!rtx_equal_p (src, SET_SRC (set))
3909 && validate_change (insn, &SET_SRC (set), src, 0))
3912 /* If we've failed to do replacement, have a single SET, don't already
3913 have a note, and have no special SET, add a REG_EQUAL note to not
3914 lose information. */
3915 if (!success && note == 0 && set != 0
3916 && GET_CODE (XEXP (set, 0)) != ZERO_EXTRACT
3917 && GET_CODE (XEXP (set, 0)) != SIGN_EXTRACT)
3918 note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
3921 /* REG_EQUAL may get simplified into register.
3922 We don't allow that. Remove that note. This code ought
3923 not to happen, because previous code ought to synthesize
3924 reg-reg move, but be on the safe side. */
3925 if (note && REG_P (XEXP (note, 0)))
3926 remove_note (insn, note);
3931 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
3932 NULL no such set is found. */
3934 static struct expr *
3935 find_avail_set (int regno, rtx insn)
3937 /* SET1 contains the last set found that can be returned to the caller for
3938 use in a substitution. */
3939 struct expr *set1 = 0;
3941 /* Loops are not possible here. To get a loop we would need two sets
3942 available at the start of the block containing INSN. ie we would
3943 need two sets like this available at the start of the block:
3945 (set (reg X) (reg Y))
3946 (set (reg Y) (reg X))
3948 This can not happen since the set of (reg Y) would have killed the
3949 set of (reg X) making it unavailable at the start of this block. */
3953 struct expr *set = lookup_set (regno, &set_hash_table);
3955 /* Find a set that is available at the start of the block
3956 which contains INSN. */
3959 if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
3961 set = next_set (regno, set);
3964 /* If no available set was found we've reached the end of the
3965 (possibly empty) copy chain. */
3969 if (GET_CODE (set->expr) != SET)
3972 src = SET_SRC (set->expr);
3974 /* We know the set is available.
3975 Now check that SRC is ANTLOC (i.e. none of the source operands
3976 have changed since the start of the block).
3978 If the source operand changed, we may still use it for the next
3979 iteration of this loop, but we may not use it for substitutions. */
3981 if (gcse_constant_p (src) || oprs_not_set_p (src, insn))
3984 /* If the source of the set is anything except a register, then
3985 we have reached the end of the copy chain. */
3986 if (GET_CODE (src) != REG)
3989 /* Follow the copy chain, ie start another iteration of the loop
3990 and see if we have an available copy into SRC. */
3991 regno = REGNO (src);
3994 /* SET1 holds the last set that was available and anticipatable at
3999 /* Subroutine of cprop_insn that tries to propagate constants into
4000 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
4001 it is the instruction that immediately precedes JUMP, and must be a
4002 single SET of a register. FROM is what we will try to replace,
4003 SRC is the constant we will try to substitute for it. Returns nonzero
4004 if a change was made. */
4007 cprop_jump (basic_block bb, rtx setcc, rtx jump, rtx from, rtx src)
4009 rtx new, set_src, note_src;
4010 rtx set = pc_set (jump);
4011 rtx note = find_reg_equal_equiv_note (jump);
4015 note_src = XEXP (note, 0);
4016 if (GET_CODE (note_src) == EXPR_LIST)
4017 note_src = NULL_RTX;
4019 else note_src = NULL_RTX;
4021 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
4022 set_src = note_src ? note_src : SET_SRC (set);
4024 /* First substitute the SETCC condition into the JUMP instruction,
4025 then substitute that given values into this expanded JUMP. */
4026 if (setcc != NULL_RTX
4027 && !modified_between_p (from, setcc, jump)
4028 && !modified_between_p (src, setcc, jump))
4031 rtx setcc_set = single_set (setcc);
4032 rtx setcc_note = find_reg_equal_equiv_note (setcc);
4033 setcc_src = (setcc_note && GET_CODE (XEXP (setcc_note, 0)) != EXPR_LIST)
4034 ? XEXP (setcc_note, 0) : SET_SRC (setcc_set);
4035 set_src = simplify_replace_rtx (set_src, SET_DEST (setcc_set),
4041 new = simplify_replace_rtx (set_src, from, src);
4043 /* If no simplification can be made, then try the next register. */
4044 if (rtx_equal_p (new, SET_SRC (set)))
4047 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
4052 /* Ensure the value computed inside the jump insn to be equivalent
4053 to one computed by setcc. */
4054 if (setcc && modified_in_p (new, setcc))
4056 if (! validate_change (jump, &SET_SRC (set), new, 0))
4058 /* When (some) constants are not valid in a comparison, and there
4059 are two registers to be replaced by constants before the entire
4060 comparison can be folded into a constant, we need to keep
4061 intermediate information in REG_EQUAL notes. For targets with
4062 separate compare insns, such notes are added by try_replace_reg.
4063 When we have a combined compare-and-branch instruction, however,
4064 we need to attach a note to the branch itself to make this
4065 optimization work. */
4067 if (!rtx_equal_p (new, note_src))
4068 set_unique_reg_note (jump, REG_EQUAL, copy_rtx (new));
4072 /* Remove REG_EQUAL note after simplification. */
4074 remove_note (jump, note);
4076 /* If this has turned into an unconditional jump,
4077 then put a barrier after it so that the unreachable
4078 code will be deleted. */
4079 if (GET_CODE (SET_SRC (set)) == LABEL_REF)
4080 emit_barrier_after (jump);
4084 /* Delete the cc0 setter. */
4085 if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
4086 delete_insn (setcc);
4089 run_jump_opt_after_gcse = 1;
4092 if (gcse_file != NULL)
4095 "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
4096 REGNO (from), INSN_UID (jump));
4097 print_rtl (gcse_file, src);
4098 fprintf (gcse_file, "\n");
4100 purge_dead_edges (bb);
4106 constprop_register (rtx insn, rtx from, rtx to, int alter_jumps)
4110 /* Check for reg or cc0 setting instructions followed by
4111 conditional branch instructions first. */
4113 && (sset = single_set (insn)) != NULL
4115 && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
4117 rtx dest = SET_DEST (sset);
4118 if ((REG_P (dest) || CC0_P (dest))
4119 && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to))
4123 /* Handle normal insns next. */
4124 if (GET_CODE (insn) == INSN
4125 && try_replace_reg (from, to, insn))
4128 /* Try to propagate a CONST_INT into a conditional jump.
4129 We're pretty specific about what we will handle in this
4130 code, we can extend this as necessary over time.
4132 Right now the insn in question must look like
4133 (set (pc) (if_then_else ...)) */
4134 else if (alter_jumps && any_condjump_p (insn) && onlyjump_p (insn))
4135 return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to);
4139 /* Perform constant and copy propagation on INSN.
4140 The result is nonzero if a change was made. */
4143 cprop_insn (rtx insn, int alter_jumps)
4145 struct reg_use *reg_used;
4153 note_uses (&PATTERN (insn), find_used_regs, NULL);
4155 note = find_reg_equal_equiv_note (insn);
4157 /* We may win even when propagating constants into notes. */
4159 find_used_regs (&XEXP (note, 0), NULL);
4161 for (reg_used = ®_use_table[0]; reg_use_count > 0;
4162 reg_used++, reg_use_count--)
4164 unsigned int regno = REGNO (reg_used->reg_rtx);
4168 /* Ignore registers created by GCSE.
4169 We do this because ... */
4170 if (regno >= max_gcse_regno)
4173 /* If the register has already been set in this block, there's
4174 nothing we can do. */
4175 if (! oprs_not_set_p (reg_used->reg_rtx, insn))
4178 /* Find an assignment that sets reg_used and is available
4179 at the start of the block. */
4180 set = find_avail_set (regno, insn);
4185 /* ??? We might be able to handle PARALLELs. Later. */
4186 if (GET_CODE (pat) != SET)
4189 src = SET_SRC (pat);
4191 /* Constant propagation. */
4192 if (gcse_constant_p (src))
4194 if (constprop_register (insn, reg_used->reg_rtx, src, alter_jumps))
4198 if (gcse_file != NULL)
4200 fprintf (gcse_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
4201 fprintf (gcse_file, "insn %d with constant ", INSN_UID (insn));
4202 print_rtl (gcse_file, src);
4203 fprintf (gcse_file, "\n");
4205 if (INSN_DELETED_P (insn))
4209 else if (GET_CODE (src) == REG
4210 && REGNO (src) >= FIRST_PSEUDO_REGISTER
4211 && REGNO (src) != regno)
4213 if (try_replace_reg (reg_used->reg_rtx, src, insn))
4217 if (gcse_file != NULL)
4219 fprintf (gcse_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
4220 regno, INSN_UID (insn));
4221 fprintf (gcse_file, " with reg %d\n", REGNO (src));
4224 /* The original insn setting reg_used may or may not now be
4225 deletable. We leave the deletion to flow. */
4226 /* FIXME: If it turns out that the insn isn't deletable,
4227 then we may have unnecessarily extended register lifetimes
4228 and made things worse. */
4236 /* Like find_used_regs, but avoid recording uses that appear in
4237 input-output contexts such as zero_extract or pre_dec. This
4238 restricts the cases we consider to those for which local cprop
4239 can legitimately make replacements. */
4242 local_cprop_find_used_regs (rtx *xptr, void *data)
4249 switch (GET_CODE (x))
4253 case STRICT_LOW_PART:
4262 /* Can only legitimately appear this early in the context of
4263 stack pushes for function arguments, but handle all of the
4264 codes nonetheless. */
4268 /* Setting a subreg of a register larger than word_mode leaves
4269 the non-written words unchanged. */
4270 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
4278 find_used_regs (xptr, data);
4281 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4282 their REG_EQUAL notes need updating. */
4285 do_local_cprop (rtx x, rtx insn, int alter_jumps, rtx *libcall_sp)
4287 rtx newreg = NULL, newcnst = NULL;
4289 /* Rule out USE instructions and ASM statements as we don't want to
4290 change the hard registers mentioned. */
4291 if (GET_CODE (x) == REG
4292 && (REGNO (x) >= FIRST_PSEUDO_REGISTER
4293 || (GET_CODE (PATTERN (insn)) != USE
4294 && asm_noperands (PATTERN (insn)) < 0)))
4296 cselib_val *val = cselib_lookup (x, GET_MODE (x), 0);
4297 struct elt_loc_list *l;
4301 for (l = val->locs; l; l = l->next)
4303 rtx this_rtx = l->loc;
4309 if (gcse_constant_p (this_rtx))
4311 if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
4312 /* Don't copy propagate if it has attached REG_EQUIV note.
4313 At this point this only function parameters should have
4314 REG_EQUIV notes and if the argument slot is used somewhere
4315 explicitly, it means address of parameter has been taken,
4316 so we should not extend the lifetime of the pseudo. */
4317 && (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX))
4318 || GET_CODE (XEXP (note, 0)) != MEM))
4321 if (newcnst && constprop_register (insn, x, newcnst, alter_jumps))
4323 /* If we find a case where we can't fix the retval REG_EQUAL notes
4324 match the new register, we either have to abandon this replacement
4325 or fix delete_trivially_dead_insns to preserve the setting insn,
4326 or make it delete the REG_EUAQL note, and fix up all passes that
4327 require the REG_EQUAL note there. */
4328 if (!adjust_libcall_notes (x, newcnst, insn, libcall_sp))
4330 if (gcse_file != NULL)
4332 fprintf (gcse_file, "LOCAL CONST-PROP: Replacing reg %d in ",
4334 fprintf (gcse_file, "insn %d with constant ",
4336 print_rtl (gcse_file, newcnst);
4337 fprintf (gcse_file, "\n");
4342 else if (newreg && newreg != x && try_replace_reg (x, newreg, insn))
4344 adjust_libcall_notes (x, newreg, insn, libcall_sp);
4345 if (gcse_file != NULL)
4348 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
4349 REGNO (x), INSN_UID (insn));
4350 fprintf (gcse_file, " with reg %d\n", REGNO (newreg));
4359 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4360 their REG_EQUAL notes need updating to reflect that OLDREG has been
4361 replaced with NEWVAL in INSN. Return true if all substitutions could
4364 adjust_libcall_notes (rtx oldreg, rtx newval, rtx insn, rtx *libcall_sp)
4368 while ((end = *libcall_sp++))
4370 rtx note = find_reg_equal_equiv_note (end);
4377 if (reg_set_between_p (newval, PREV_INSN (insn), end))
4381 note = find_reg_equal_equiv_note (end);
4384 if (reg_mentioned_p (newval, XEXP (note, 0)))
4387 while ((end = *libcall_sp++));
4391 XEXP (note, 0) = replace_rtx (XEXP (note, 0), oldreg, newval);
4397 #define MAX_NESTED_LIBCALLS 9
4400 local_cprop_pass (int alter_jumps)
4403 struct reg_use *reg_used;
4404 rtx libcall_stack[MAX_NESTED_LIBCALLS + 1], *libcall_sp;
4405 bool changed = false;
4408 libcall_sp = &libcall_stack[MAX_NESTED_LIBCALLS];
4410 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4414 rtx note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
4418 if (libcall_sp == libcall_stack)
4420 *--libcall_sp = XEXP (note, 0);
4422 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
4425 note = find_reg_equal_equiv_note (insn);
4429 note_uses (&PATTERN (insn), local_cprop_find_used_regs, NULL);
4431 local_cprop_find_used_regs (&XEXP (note, 0), NULL);
4433 for (reg_used = ®_use_table[0]; reg_use_count > 0;
4434 reg_used++, reg_use_count--)
4435 if (do_local_cprop (reg_used->reg_rtx, insn, alter_jumps,
4441 if (INSN_DELETED_P (insn))
4444 while (reg_use_count);
4446 cselib_process_insn (insn);
4449 /* Global analysis may get into infinite loops for unreachable blocks. */
4450 if (changed && alter_jumps)
4452 delete_unreachable_blocks ();
4453 free_reg_set_mem ();
4454 alloc_reg_set_mem (max_reg_num ());
4455 compute_sets (get_insns ());
4459 /* Forward propagate copies. This includes copies and constants. Return
4460 nonzero if a change was made. */
4463 cprop (int alter_jumps)
4469 /* Note we start at block 1. */
4470 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
4472 if (gcse_file != NULL)
4473 fprintf (gcse_file, "\n");
4478 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
4480 /* Reset tables used to keep track of what's still valid [since the
4481 start of the block]. */
4482 reset_opr_set_tables ();
4484 for (insn = BB_HEAD (bb);
4485 insn != NULL && insn != NEXT_INSN (BB_END (bb));
4486 insn = NEXT_INSN (insn))
4489 changed |= cprop_insn (insn, alter_jumps);
4491 /* Keep track of everything modified by this insn. */
4492 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
4493 call mark_oprs_set if we turned the insn into a NOTE. */
4494 if (GET_CODE (insn) != NOTE)
4495 mark_oprs_set (insn);
4499 if (gcse_file != NULL)
4500 fprintf (gcse_file, "\n");
4505 /* Similar to get_condition, only the resulting condition must be
4506 valid at JUMP, instead of at EARLIEST.
4508 This differs from noce_get_condition in ifcvt.c in that we prefer not to
4509 settle for the condition variable in the jump instruction being integral.
4510 We prefer to be able to record the value of a user variable, rather than
4511 the value of a temporary used in a condition. This could be solved by
4512 recording the value of *every* register scaned by canonicalize_condition,
4513 but this would require some code reorganization. */
4516 fis_get_condition (rtx jump)
4518 rtx cond, set, tmp, insn, earliest;
4521 if (! any_condjump_p (jump))
4524 set = pc_set (jump);
4525 cond = XEXP (SET_SRC (set), 0);
4527 /* If this branches to JUMP_LABEL when the condition is false,
4528 reverse the condition. */
4529 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
4530 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
4532 /* Use canonicalize_condition to do the dirty work of manipulating
4533 MODE_CC values and COMPARE rtx codes. */
4534 tmp = canonicalize_condition (jump, cond, reverse, &earliest, NULL_RTX,
4539 /* Verify that the given condition is valid at JUMP by virtue of not
4540 having been modified since EARLIEST. */
4541 for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
4542 if (INSN_P (insn) && modified_in_p (tmp, insn))
4547 /* The condition was modified. See if we can get a partial result
4548 that doesn't follow all the reversals. Perhaps combine can fold
4549 them together later. */
4550 tmp = XEXP (tmp, 0);
4551 if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
4553 tmp = canonicalize_condition (jump, cond, reverse, &earliest, tmp,
4558 /* For sanity's sake, re-validate the new result. */
4559 for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
4560 if (INSN_P (insn) && modified_in_p (tmp, insn))
4566 /* Check the comparison COND to see if we can safely form an implicit set from
4567 it. COND is either an EQ or NE comparison. */
4570 implicit_set_cond_p (rtx cond)
4572 enum machine_mode mode = GET_MODE (XEXP (cond, 0));
4573 rtx cst = XEXP (cond, 1);
4575 /* We can't perform this optimization if either operand might be or might
4576 contain a signed zero. */
4577 if (HONOR_SIGNED_ZEROS (mode))
4579 /* It is sufficient to check if CST is or contains a zero. We must
4580 handle float, complex, and vector. If any subpart is a zero, then
4581 the optimization can't be performed. */
4582 /* ??? The complex and vector checks are not implemented yet. We just
4583 always return zero for them. */
4584 if (GET_CODE (cst) == CONST_DOUBLE)
4587 REAL_VALUE_FROM_CONST_DOUBLE (d, cst);
4588 if (REAL_VALUES_EQUAL (d, dconst0))
4595 return gcse_constant_p (cst);
4598 /* Find the implicit sets of a function. An "implicit set" is a constraint
4599 on the value of a variable, implied by a conditional jump. For example,
4600 following "if (x == 2)", the then branch may be optimized as though the
4601 conditional performed an "explicit set", in this example, "x = 2". This
4602 function records the set patterns that are implicit at the start of each
4606 find_implicit_sets (void)
4608 basic_block bb, dest;
4614 /* Check for more than one successor. */
4615 if (bb->succ && bb->succ->succ_next)
4617 cond = fis_get_condition (BB_END (bb));
4620 && (GET_CODE (cond) == EQ || GET_CODE (cond) == NE)
4621 && GET_CODE (XEXP (cond, 0)) == REG
4622 && REGNO (XEXP (cond, 0)) >= FIRST_PSEUDO_REGISTER
4623 && implicit_set_cond_p (cond))
4625 dest = GET_CODE (cond) == EQ ? BRANCH_EDGE (bb)->dest
4626 : FALLTHRU_EDGE (bb)->dest;
4628 if (dest && ! dest->pred->pred_next
4629 && dest != EXIT_BLOCK_PTR)
4631 new = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
4633 implicit_sets[dest->index] = new;
4636 fprintf(gcse_file, "Implicit set of reg %d in ",
4637 REGNO (XEXP (cond, 0)));
4638 fprintf(gcse_file, "basic block %d\n", dest->index);
4646 fprintf (gcse_file, "Found %d implicit sets\n", count);
4649 /* Perform one copy/constant propagation pass.
4650 PASS is the pass count. If CPROP_JUMPS is true, perform constant
4651 propagation into conditional jumps. If BYPASS_JUMPS is true,
4652 perform conditional jump bypassing optimizations. */
4655 one_cprop_pass (int pass, int cprop_jumps, int bypass_jumps)
4659 const_prop_count = 0;
4660 copy_prop_count = 0;
4662 local_cprop_pass (cprop_jumps);
4664 /* Determine implicit sets. */
4665 implicit_sets = xcalloc (last_basic_block, sizeof (rtx));
4666 find_implicit_sets ();
4668 alloc_hash_table (max_cuid, &set_hash_table, 1);
4669 compute_hash_table (&set_hash_table);
4671 /* Free implicit_sets before peak usage. */
4672 free (implicit_sets);
4673 implicit_sets = NULL;
4676 dump_hash_table (gcse_file, "SET", &set_hash_table);
4677 if (set_hash_table.n_elems > 0)
4679 alloc_cprop_mem (last_basic_block, set_hash_table.n_elems);
4680 compute_cprop_data ();
4681 changed = cprop (cprop_jumps);
4683 changed |= bypass_conditional_jumps ();
4687 free_hash_table (&set_hash_table);
4691 fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, ",
4692 (*lang_hooks.decl_printable_name) (current_function_decl, 2),
4694 fprintf (gcse_file, "%d const props, %d copy props\n\n",
4695 const_prop_count, copy_prop_count);
4697 /* Global analysis may get into infinite loops for unreachable blocks. */
4698 if (changed && cprop_jumps)
4699 delete_unreachable_blocks ();
4704 /* Bypass conditional jumps. */
4706 /* The value of last_basic_block at the beginning of the jump_bypass
4707 pass. The use of redirect_edge_and_branch_force may introduce new
4708 basic blocks, but the data flow analysis is only valid for basic
4709 block indices less than bypass_last_basic_block. */
4711 static int bypass_last_basic_block;
4713 /* Find a set of REGNO to a constant that is available at the end of basic
4714 block BB. Returns NULL if no such set is found. Based heavily upon
4717 static struct expr *
4718 find_bypass_set (int regno, int bb)
4720 struct expr *result = 0;
4725 struct expr *set = lookup_set (regno, &set_hash_table);
4729 if (TEST_BIT (cprop_avout[bb], set->bitmap_index))
4731 set = next_set (regno, set);
4737 if (GET_CODE (set->expr) != SET)
4740 src = SET_SRC (set->expr);
4741 if (gcse_constant_p (src))
4744 if (GET_CODE (src) != REG)
4747 regno = REGNO (src);
4753 /* Subroutine of bypass_block that checks whether a pseudo is killed by
4754 any of the instructions inserted on an edge. Jump bypassing places
4755 condition code setters on CFG edges using insert_insn_on_edge. This
4756 function is required to check that our data flow analysis is still
4757 valid prior to commit_edge_insertions. */
4760 reg_killed_on_edge (rtx reg, edge e)
4764 for (insn = e->insns; insn; insn = NEXT_INSN (insn))
4765 if (INSN_P (insn) && reg_set_p (reg, insn))
4771 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
4772 basic block BB which has more than one predecessor. If not NULL, SETCC
4773 is the first instruction of BB, which is immediately followed by JUMP_INSN
4774 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
4775 Returns nonzero if a change was made.
4777 During the jump bypassing pass, we may place copies of SETCC instructions
4778 on CFG edges. The following routine must be careful to pay attention to
4779 these inserted insns when performing its transformations. */
4782 bypass_block (basic_block bb, rtx setcc, rtx jump)
4785 edge e, enext, edest;
4787 int may_be_loop_header;
4789 insn = (setcc != NULL) ? setcc : jump;
4791 /* Determine set of register uses in INSN. */
4793 note_uses (&PATTERN (insn), find_used_regs, NULL);
4794 note = find_reg_equal_equiv_note (insn);
4796 find_used_regs (&XEXP (note, 0), NULL);
4798 may_be_loop_header = false;
4799 for (e = bb->pred; e; e = e->pred_next)
4800 if (e->flags & EDGE_DFS_BACK)
4802 may_be_loop_header = true;
4807 for (e = bb->pred; e; e = enext)
4809 enext = e->pred_next;
4810 if (e->flags & EDGE_COMPLEX)
4813 /* We can't redirect edges from new basic blocks. */
4814 if (e->src->index >= bypass_last_basic_block)
4817 /* The irreducible loops created by redirecting of edges entering the
4818 loop from outside would decrease effectiveness of some of the following
4819 optimizations, so prevent this. */
4820 if (may_be_loop_header
4821 && !(e->flags & EDGE_DFS_BACK))
4824 for (i = 0; i < reg_use_count; i++)
4826 struct reg_use *reg_used = ®_use_table[i];
4827 unsigned int regno = REGNO (reg_used->reg_rtx);
4828 basic_block dest, old_dest;
4832 if (regno >= max_gcse_regno)
4835 set = find_bypass_set (regno, e->src->index);
4840 /* Check the data flow is valid after edge insertions. */
4841 if (e->insns && reg_killed_on_edge (reg_used->reg_rtx, e))
4844 src = SET_SRC (pc_set (jump));
4847 src = simplify_replace_rtx (src,
4848 SET_DEST (PATTERN (setcc)),
4849 SET_SRC (PATTERN (setcc)));
4851 new = simplify_replace_rtx (src, reg_used->reg_rtx,
4852 SET_SRC (set->expr));
4854 /* Jump bypassing may have already placed instructions on
4855 edges of the CFG. We can't bypass an outgoing edge that
4856 has instructions associated with it, as these insns won't
4857 get executed if the incoming edge is redirected. */
4861 edest = FALLTHRU_EDGE (bb);
4862 dest = edest->insns ? NULL : edest->dest;
4864 else if (GET_CODE (new) == LABEL_REF)
4866 dest = BLOCK_FOR_INSN (XEXP (new, 0));
4867 /* Don't bypass edges containing instructions. */
4868 for (edest = bb->succ; edest; edest = edest->succ_next)
4869 if (edest->dest == dest && edest->insns)
4881 && dest != EXIT_BLOCK_PTR)
4883 redirect_edge_and_branch_force (e, dest);
4885 /* Copy the register setter to the redirected edge.
4886 Don't copy CC0 setters, as CC0 is dead after jump. */
4889 rtx pat = PATTERN (setcc);
4890 if (!CC0_P (SET_DEST (pat)))
4891 insert_insn_on_edge (copy_insn (pat), e);
4894 if (gcse_file != NULL)
4896 fprintf (gcse_file, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
4897 regno, INSN_UID (jump));
4898 print_rtl (gcse_file, SET_SRC (set->expr));
4899 fprintf (gcse_file, "\nBypass edge from %d->%d to %d\n",
4900 e->src->index, old_dest->index, dest->index);
4910 /* Find basic blocks with more than one predecessor that only contain a
4911 single conditional jump. If the result of the comparison is known at
4912 compile-time from any incoming edge, redirect that edge to the
4913 appropriate target. Returns nonzero if a change was made.
4915 This function is now mis-named, because we also handle indirect jumps. */
4918 bypass_conditional_jumps (void)
4926 /* Note we start at block 1. */
4927 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
4930 bypass_last_basic_block = last_basic_block;
4931 mark_dfs_back_edges ();
4934 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb,
4935 EXIT_BLOCK_PTR, next_bb)
4937 /* Check for more than one predecessor. */
4938 if (bb->pred && bb->pred->pred_next)
4941 for (insn = BB_HEAD (bb);
4942 insn != NULL && insn != NEXT_INSN (BB_END (bb));
4943 insn = NEXT_INSN (insn))
4944 if (GET_CODE (insn) == INSN)
4948 if (GET_CODE (PATTERN (insn)) != SET)
4951 dest = SET_DEST (PATTERN (insn));
4952 if (REG_P (dest) || CC0_P (dest))
4957 else if (GET_CODE (insn) == JUMP_INSN)
4959 if ((any_condjump_p (insn) || computed_jump_p (insn))
4960 && onlyjump_p (insn))
4961 changed |= bypass_block (bb, setcc, insn);
4964 else if (INSN_P (insn))
4969 /* If we bypassed any register setting insns, we inserted a
4970 copy on the redirected edge. These need to be committed. */
4972 commit_edge_insertions();
4977 /* Compute PRE+LCM working variables. */
4979 /* Local properties of expressions. */
4980 /* Nonzero for expressions that are transparent in the block. */
4981 static sbitmap *transp;
4983 /* Nonzero for expressions that are transparent at the end of the block.
4984 This is only zero for expressions killed by abnormal critical edge
4985 created by a calls. */
4986 static sbitmap *transpout;
4988 /* Nonzero for expressions that are computed (available) in the block. */
4989 static sbitmap *comp;
4991 /* Nonzero for expressions that are locally anticipatable in the block. */
4992 static sbitmap *antloc;
4994 /* Nonzero for expressions where this block is an optimal computation
4996 static sbitmap *pre_optimal;
4998 /* Nonzero for expressions which are redundant in a particular block. */
4999 static sbitmap *pre_redundant;
5001 /* Nonzero for expressions which should be inserted on a specific edge. */
5002 static sbitmap *pre_insert_map;
5004 /* Nonzero for expressions which should be deleted in a specific block. */
5005 static sbitmap *pre_delete_map;
5007 /* Contains the edge_list returned by pre_edge_lcm. */
5008 static struct edge_list *edge_list;
5010 /* Redundant insns. */
5011 static sbitmap pre_redundant_insns;
5013 /* Allocate vars used for PRE analysis. */
5016 alloc_pre_mem (int n_blocks, int n_exprs)
5018 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
5019 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
5020 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
5023 pre_redundant = NULL;
5024 pre_insert_map = NULL;
5025 pre_delete_map = NULL;
5028 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
5030 /* pre_insert and pre_delete are allocated later. */
5033 /* Free vars used for PRE analysis. */
5038 sbitmap_vector_free (transp);
5039 sbitmap_vector_free (comp);
5041 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
5044 sbitmap_vector_free (pre_optimal);
5046 sbitmap_vector_free (pre_redundant);
5048 sbitmap_vector_free (pre_insert_map);
5050 sbitmap_vector_free (pre_delete_map);
5052 sbitmap_vector_free (ae_in);
5054 sbitmap_vector_free (ae_out);
5056 transp = comp = NULL;
5057 pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
5058 ae_in = ae_out = NULL;
5061 /* Top level routine to do the dataflow analysis needed by PRE. */
5064 compute_pre_data (void)
5066 sbitmap trapping_expr;
5070 compute_local_properties (transp, comp, antloc, &expr_hash_table);
5071 sbitmap_vector_zero (ae_kill, last_basic_block);
5073 /* Collect expressions which might trap. */
5074 trapping_expr = sbitmap_alloc (expr_hash_table.n_elems);
5075 sbitmap_zero (trapping_expr);
5076 for (ui = 0; ui < expr_hash_table.size; ui++)
5079 for (e = expr_hash_table.table[ui]; e != NULL; e = e->next_same_hash)
5080 if (may_trap_p (e->expr))
5081 SET_BIT (trapping_expr, e->bitmap_index);
5084 /* Compute ae_kill for each basic block using:
5088 This is significantly faster than compute_ae_kill. */
5094 /* If the current block is the destination of an abnormal edge, we
5095 kill all trapping expressions because we won't be able to properly
5096 place the instruction on the edge. So make them neither
5097 anticipatable nor transparent. This is fairly conservative. */
5098 for (e = bb->pred; e ; e = e->pred_next)
5099 if (e->flags & EDGE_ABNORMAL)
5101 sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr);
5102 sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr);
5106 sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]);
5107 sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]);
5110 edge_list = pre_edge_lcm (gcse_file, expr_hash_table.n_elems, transp, comp, antloc,
5111 ae_kill, &pre_insert_map, &pre_delete_map);
5112 sbitmap_vector_free (antloc);
5114 sbitmap_vector_free (ae_kill);
5116 sbitmap_free (trapping_expr);
5121 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
5124 VISITED is a pointer to a working buffer for tracking which BB's have
5125 been visited. It is NULL for the top-level call.
5127 We treat reaching expressions that go through blocks containing the same
5128 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
5129 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
5130 2 as not reaching. The intent is to improve the probability of finding
5131 only one reaching expression and to reduce register lifetimes by picking
5132 the closest such expression. */
5135 pre_expr_reaches_here_p_work (basic_block occr_bb, struct expr *expr, basic_block bb, char *visited)
5139 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
5141 basic_block pred_bb = pred->src;
5143 if (pred->src == ENTRY_BLOCK_PTR
5144 /* Has predecessor has already been visited? */
5145 || visited[pred_bb->index])
5146 ;/* Nothing to do. */
5148 /* Does this predecessor generate this expression? */
5149 else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
5151 /* Is this the occurrence we're looking for?
5152 Note that there's only one generating occurrence per block
5153 so we just need to check the block number. */
5154 if (occr_bb == pred_bb)
5157 visited[pred_bb->index] = 1;
5159 /* Ignore this predecessor if it kills the expression. */
5160 else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
5161 visited[pred_bb->index] = 1;
5163 /* Neither gen nor kill. */
5166 visited[pred_bb->index] = 1;
5167 if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
5172 /* All paths have been checked. */
5176 /* The wrapper for pre_expr_reaches_here_work that ensures that any
5177 memory allocated for that function is returned. */
5180 pre_expr_reaches_here_p (basic_block occr_bb, struct expr *expr, basic_block bb)
5183 char *visited = xcalloc (last_basic_block, 1);
5185 rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited);
5192 /* Given an expr, generate RTL which we can insert at the end of a BB,
5193 or on an edge. Set the block number of any insns generated to
5197 process_insert_insn (struct expr *expr)
5199 rtx reg = expr->reaching_reg;
5200 rtx exp = copy_rtx (expr->expr);
5205 /* If the expression is something that's an operand, like a constant,
5206 just copy it to a register. */
5207 if (general_operand (exp, GET_MODE (reg)))
5208 emit_move_insn (reg, exp);
5210 /* Otherwise, make a new insn to compute this expression and make sure the
5211 insn will be recognized (this also adds any needed CLOBBERs). Copy the
5212 expression to make sure we don't have any sharing issues. */
5213 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode, reg, exp))))
5222 /* Add EXPR to the end of basic block BB.
5224 This is used by both the PRE and code hoisting.
5226 For PRE, we want to verify that the expr is either transparent
5227 or locally anticipatable in the target block. This check makes
5228 no sense for code hoisting. */
5231 insert_insn_end_bb (struct expr *expr, basic_block bb, int pre)
5233 rtx insn = BB_END (bb);
5235 rtx reg = expr->reaching_reg;
5236 int regno = REGNO (reg);
5239 pat = process_insert_insn (expr);
5240 if (pat == NULL_RTX || ! INSN_P (pat))
5244 while (NEXT_INSN (pat_end) != NULL_RTX)
5245 pat_end = NEXT_INSN (pat_end);
5247 /* If the last insn is a jump, insert EXPR in front [taking care to
5248 handle cc0, etc. properly]. Similarly we need to care trapping
5249 instructions in presence of non-call exceptions. */
5251 if (GET_CODE (insn) == JUMP_INSN
5252 || (GET_CODE (insn) == INSN
5253 && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL))))
5258 /* It should always be the case that we can put these instructions
5259 anywhere in the basic block with performing PRE optimizations.
5261 if (GET_CODE (insn) == INSN && pre
5262 && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
5263 && !TEST_BIT (transp[bb->index], expr->bitmap_index))
5266 /* If this is a jump table, then we can't insert stuff here. Since
5267 we know the previous real insn must be the tablejump, we insert
5268 the new instruction just before the tablejump. */
5269 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
5270 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
5271 insn = prev_real_insn (insn);
5274 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
5275 if cc0 isn't set. */
5276 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
5278 insn = XEXP (note, 0);
5281 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
5282 if (maybe_cc0_setter
5283 && INSN_P (maybe_cc0_setter)
5284 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
5285 insn = maybe_cc0_setter;
5288 /* FIXME: What if something in cc0/jump uses value set in new insn? */
5289 new_insn = emit_insn_before (pat, insn);
5292 /* Likewise if the last insn is a call, as will happen in the presence
5293 of exception handling. */
5294 else if (GET_CODE (insn) == CALL_INSN
5295 && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL)))
5297 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
5298 we search backward and place the instructions before the first
5299 parameter is loaded. Do this for everyone for consistency and a
5300 presumption that we'll get better code elsewhere as well.
5302 It should always be the case that we can put these instructions
5303 anywhere in the basic block with performing PRE optimizations.
5307 && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
5308 && !TEST_BIT (transp[bb->index], expr->bitmap_index))
5311 /* Since different machines initialize their parameter registers
5312 in different orders, assume nothing. Collect the set of all
5313 parameter registers. */
5314 insn = find_first_parameter_load (insn, BB_HEAD (bb));
5316 /* If we found all the parameter loads, then we want to insert
5317 before the first parameter load.
5319 If we did not find all the parameter loads, then we might have
5320 stopped on the head of the block, which could be a CODE_LABEL.
5321 If we inserted before the CODE_LABEL, then we would be putting
5322 the insn in the wrong basic block. In that case, put the insn
5323 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
5324 while (GET_CODE (insn) == CODE_LABEL
5325 || NOTE_INSN_BASIC_BLOCK_P (insn))
5326 insn = NEXT_INSN (insn);
5328 new_insn = emit_insn_before (pat, insn);
5331 new_insn = emit_insn_after (pat, insn);
5337 add_label_notes (PATTERN (pat), new_insn);
5338 note_stores (PATTERN (pat), record_set_info, pat);
5342 pat = NEXT_INSN (pat);
5345 gcse_create_count++;
5349 fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, ",
5350 bb->index, INSN_UID (new_insn));
5351 fprintf (gcse_file, "copying expression %d to reg %d\n",
5352 expr->bitmap_index, regno);
5356 /* Insert partially redundant expressions on edges in the CFG to make
5357 the expressions fully redundant. */
5360 pre_edge_insert (struct edge_list *edge_list, struct expr **index_map)
5362 int e, i, j, num_edges, set_size, did_insert = 0;
5365 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
5366 if it reaches any of the deleted expressions. */
5368 set_size = pre_insert_map[0]->size;
5369 num_edges = NUM_EDGES (edge_list);
5370 inserted = sbitmap_vector_alloc (num_edges, expr_hash_table.n_elems);
5371 sbitmap_vector_zero (inserted, num_edges);
5373 for (e = 0; e < num_edges; e++)
5376 basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
5378 for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
5380 SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
5382 for (j = indx; insert && j < (int) expr_hash_table.n_elems; j++, insert >>= 1)
5383 if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
5385 struct expr *expr = index_map[j];
5388 /* Now look at each deleted occurrence of this expression. */
5389 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5391 if (! occr->deleted_p)
5394 /* Insert this expression on this edge if if it would
5395 reach the deleted occurrence in BB. */
5396 if (!TEST_BIT (inserted[e], j))
5399 edge eg = INDEX_EDGE (edge_list, e);
5401 /* We can't insert anything on an abnormal and
5402 critical edge, so we insert the insn at the end of
5403 the previous block. There are several alternatives
5404 detailed in Morgans book P277 (sec 10.5) for
5405 handling this situation. This one is easiest for
5408 if ((eg->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
5409 insert_insn_end_bb (index_map[j], bb, 0);
5412 insn = process_insert_insn (index_map[j]);
5413 insert_insn_on_edge (insn, eg);
5418 fprintf (gcse_file, "PRE/HOIST: edge (%d,%d), ",
5420 INDEX_EDGE_SUCC_BB (edge_list, e)->index);
5421 fprintf (gcse_file, "copy expression %d\n",
5422 expr->bitmap_index);
5425 update_ld_motion_stores (expr);
5426 SET_BIT (inserted[e], j);
5428 gcse_create_count++;
5435 sbitmap_vector_free (inserted);
5439 /* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
5440 Given "old_reg <- expr" (INSN), instead of adding after it
5441 reaching_reg <- old_reg
5442 it's better to do the following:
5443 reaching_reg <- expr
5444 old_reg <- reaching_reg
5445 because this way copy propagation can discover additional PRE
5446 opportunities. But if this fails, we try the old way.
5447 When "expr" is a store, i.e.
5448 given "MEM <- old_reg", instead of adding after it
5449 reaching_reg <- old_reg
5450 it's better to add it before as follows:
5451 reaching_reg <- old_reg
5452 MEM <- reaching_reg. */
5455 pre_insert_copy_insn (struct expr *expr, rtx insn)
5457 rtx reg = expr->reaching_reg;
5458 int regno = REGNO (reg);
5459 int indx = expr->bitmap_index;
5460 rtx pat = PATTERN (insn);
5465 /* This block matches the logic in hash_scan_insn. */
5466 if (GET_CODE (pat) == SET)
5468 else if (GET_CODE (pat) == PARALLEL)
5470 /* Search through the parallel looking for the set whose
5471 source was the expression that we're interested in. */
5473 for (i = 0; i < XVECLEN (pat, 0); i++)
5475 rtx x = XVECEXP (pat, 0, i);
5476 if (GET_CODE (x) == SET
5477 && expr_equiv_p (SET_SRC (x), expr->expr))
5487 if (GET_CODE (SET_DEST (set)) == REG)
5489 old_reg = SET_DEST (set);
5490 /* Check if we can modify the set destination in the original insn. */
5491 if (validate_change (insn, &SET_DEST (set), reg, 0))
5493 new_insn = gen_move_insn (old_reg, reg);
5494 new_insn = emit_insn_after (new_insn, insn);
5496 /* Keep register set table up to date. */
5497 replace_one_set (REGNO (old_reg), insn, new_insn);
5498 record_one_set (regno, insn);
5502 new_insn = gen_move_insn (reg, old_reg);
5503 new_insn = emit_insn_after (new_insn, insn);
5505 /* Keep register set table up to date. */
5506 record_one_set (regno, new_insn);
5509 else /* This is possible only in case of a store to memory. */
5511 old_reg = SET_SRC (set);
5512 new_insn = gen_move_insn (reg, old_reg);
5514 /* Check if we can modify the set source in the original insn. */
5515 if (validate_change (insn, &SET_SRC (set), reg, 0))
5516 new_insn = emit_insn_before (new_insn, insn);
5518 new_insn = emit_insn_after (new_insn, insn);
5520 /* Keep register set table up to date. */
5521 record_one_set (regno, new_insn);
5524 gcse_create_count++;
5528 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
5529 BLOCK_NUM (insn), INSN_UID (new_insn), indx,
5530 INSN_UID (insn), regno);
5533 /* Copy available expressions that reach the redundant expression
5534 to `reaching_reg'. */
5537 pre_insert_copies (void)
5539 unsigned int i, added_copy;
5544 /* For each available expression in the table, copy the result to
5545 `reaching_reg' if the expression reaches a deleted one.
5547 ??? The current algorithm is rather brute force.
5548 Need to do some profiling. */
5550 for (i = 0; i < expr_hash_table.size; i++)
5551 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
5553 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
5554 we don't want to insert a copy here because the expression may not
5555 really be redundant. So only insert an insn if the expression was
5556 deleted. This test also avoids further processing if the
5557 expression wasn't deleted anywhere. */
5558 if (expr->reaching_reg == NULL)
5561 /* Set when we add a copy for that expression. */
5564 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5566 if (! occr->deleted_p)
5569 for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
5571 rtx insn = avail->insn;
5573 /* No need to handle this one if handled already. */
5574 if (avail->copied_p)
5577 /* Don't handle this one if it's a redundant one. */
5578 if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
5581 /* Or if the expression doesn't reach the deleted one. */
5582 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
5584 BLOCK_FOR_INSN (occr->insn)))
5589 /* Copy the result of avail to reaching_reg. */
5590 pre_insert_copy_insn (expr, insn);
5591 avail->copied_p = 1;
5596 update_ld_motion_stores (expr);
5600 /* Emit move from SRC to DEST noting the equivalence with expression computed
5603 gcse_emit_move_after (rtx src, rtx dest, rtx insn)
5606 rtx set = single_set (insn), set2;
5610 /* This should never fail since we're creating a reg->reg copy
5611 we've verified to be valid. */
5613 new = emit_insn_after (gen_move_insn (dest, src), insn);
5615 /* Note the equivalence for local CSE pass. */
5616 set2 = single_set (new);
5617 if (!set2 || !rtx_equal_p (SET_DEST (set2), dest))
5619 if ((note = find_reg_equal_equiv_note (insn)))
5620 eqv = XEXP (note, 0);
5622 eqv = SET_SRC (set);
5624 set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (eqv));
5629 /* Delete redundant computations.
5630 Deletion is done by changing the insn to copy the `reaching_reg' of
5631 the expression into the result of the SET. It is left to later passes
5632 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
5634 Returns nonzero if a change is made. */
5645 for (i = 0; i < expr_hash_table.size; i++)
5646 for (expr = expr_hash_table.table[i];
5648 expr = expr->next_same_hash)
5650 int indx = expr->bitmap_index;
5652 /* We only need to search antic_occr since we require
5655 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5657 rtx insn = occr->insn;
5659 basic_block bb = BLOCK_FOR_INSN (insn);
5661 /* We only delete insns that have a single_set. */
5662 if (TEST_BIT (pre_delete_map[bb->index], indx)
5663 && (set = single_set (insn)) != 0)
5665 /* Create a pseudo-reg to store the result of reaching
5666 expressions into. Get the mode for the new pseudo from
5667 the mode of the original destination pseudo. */
5668 if (expr->reaching_reg == NULL)
5670 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
5672 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
5674 occr->deleted_p = 1;
5675 SET_BIT (pre_redundant_insns, INSN_CUID (insn));
5682 "PRE: redundant insn %d (expression %d) in ",
5683 INSN_UID (insn), indx);
5684 fprintf (gcse_file, "bb %d, reaching reg is %d\n",
5685 bb->index, REGNO (expr->reaching_reg));
5694 /* Perform GCSE optimizations using PRE.
5695 This is called by one_pre_gcse_pass after all the dataflow analysis
5698 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
5699 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
5700 Compiler Design and Implementation.
5702 ??? A new pseudo reg is created to hold the reaching expression. The nice
5703 thing about the classical approach is that it would try to use an existing
5704 reg. If the register can't be adequately optimized [i.e. we introduce
5705 reload problems], one could add a pass here to propagate the new register
5708 ??? We don't handle single sets in PARALLELs because we're [currently] not
5709 able to copy the rest of the parallel when we insert copies to create full
5710 redundancies from partial redundancies. However, there's no reason why we
5711 can't handle PARALLELs in the cases where there are no partial
5718 int did_insert, changed;
5719 struct expr **index_map;
5722 /* Compute a mapping from expression number (`bitmap_index') to
5723 hash table entry. */
5725 index_map = xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
5726 for (i = 0; i < expr_hash_table.size; i++)
5727 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
5728 index_map[expr->bitmap_index] = expr;
5730 /* Reset bitmap used to track which insns are redundant. */
5731 pre_redundant_insns = sbitmap_alloc (max_cuid);
5732 sbitmap_zero (pre_redundant_insns);
5734 /* Delete the redundant insns first so that
5735 - we know what register to use for the new insns and for the other
5736 ones with reaching expressions
5737 - we know which insns are redundant when we go to create copies */
5739 changed = pre_delete ();
5741 did_insert = pre_edge_insert (edge_list, index_map);
5743 /* In other places with reaching expressions, copy the expression to the
5744 specially allocated pseudo-reg that reaches the redundant expr. */
5745 pre_insert_copies ();
5748 commit_edge_insertions ();
5753 sbitmap_free (pre_redundant_insns);
5757 /* Top level routine to perform one PRE GCSE pass.
5759 Return nonzero if a change was made. */
5762 one_pre_gcse_pass (int pass)
5766 gcse_subst_count = 0;
5767 gcse_create_count = 0;
5769 alloc_hash_table (max_cuid, &expr_hash_table, 0);
5770 add_noreturn_fake_exit_edges ();
5772 compute_ld_motion_mems ();
5774 compute_hash_table (&expr_hash_table);
5775 trim_ld_motion_mems ();
5777 dump_hash_table (gcse_file, "Expression", &expr_hash_table);
5779 if (expr_hash_table.n_elems > 0)
5781 alloc_pre_mem (last_basic_block, expr_hash_table.n_elems);
5782 compute_pre_data ();
5783 changed |= pre_gcse ();
5784 free_edge_list (edge_list);
5789 remove_fake_edges ();
5790 free_hash_table (&expr_hash_table);
5794 fprintf (gcse_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
5795 (*lang_hooks.decl_printable_name) (current_function_decl, 2),
5797 fprintf (gcse_file, "%d substs, %d insns created\n",
5798 gcse_subst_count, gcse_create_count);
5804 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
5805 If notes are added to an insn which references a CODE_LABEL, the
5806 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
5807 because the following loop optimization pass requires them. */
5809 /* ??? This is very similar to the loop.c add_label_notes function. We
5810 could probably share code here. */
5812 /* ??? If there was a jump optimization pass after gcse and before loop,
5813 then we would not need to do this here, because jump would add the
5814 necessary REG_LABEL notes. */
5817 add_label_notes (rtx x, rtx insn)
5819 enum rtx_code code = GET_CODE (x);
5823 if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
5825 /* This code used to ignore labels that referred to dispatch tables to
5826 avoid flow generating (slightly) worse code.
5828 We no longer ignore such label references (see LABEL_REF handling in
5829 mark_jump_label for additional information). */
5831 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0),
5833 if (LABEL_P (XEXP (x, 0)))
5834 LABEL_NUSES (XEXP (x, 0))++;
5838 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
5841 add_label_notes (XEXP (x, i), insn);
5842 else if (fmt[i] == 'E')
5843 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5844 add_label_notes (XVECEXP (x, i, j), insn);
5848 /* Compute transparent outgoing information for each block.
5850 An expression is transparent to an edge unless it is killed by
5851 the edge itself. This can only happen with abnormal control flow,
5852 when the edge is traversed through a call. This happens with
5853 non-local labels and exceptions.
5855 This would not be necessary if we split the edge. While this is
5856 normally impossible for abnormal critical edges, with some effort
5857 it should be possible with exception handling, since we still have
5858 control over which handler should be invoked. But due to increased
5859 EH table sizes, this may not be worthwhile. */
5862 compute_transpout (void)
5868 sbitmap_vector_ones (transpout, last_basic_block);
5872 /* Note that flow inserted a nop a the end of basic blocks that
5873 end in call instructions for reasons other than abnormal
5875 if (GET_CODE (BB_END (bb)) != CALL_INSN)
5878 for (i = 0; i < expr_hash_table.size; i++)
5879 for (expr = expr_hash_table.table[i]; expr ; expr = expr->next_same_hash)
5880 if (GET_CODE (expr->expr) == MEM)
5882 if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
5883 && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
5886 /* ??? Optimally, we would use interprocedural alias
5887 analysis to determine if this mem is actually killed
5889 RESET_BIT (transpout[bb->index], expr->bitmap_index);
5894 /* Removal of useless null pointer checks */
5896 /* Called via note_stores. X is set by SETTER. If X is a register we must
5897 invalidate nonnull_local and set nonnull_killed. DATA is really a
5898 `null_pointer_info *'.
5900 We ignore hard registers. */
5903 invalidate_nonnull_info (rtx x, rtx setter ATTRIBUTE_UNUSED, void *data)
5906 struct null_pointer_info *npi = (struct null_pointer_info *) data;
5908 while (GET_CODE (x) == SUBREG)
5911 /* Ignore anything that is not a register or is a hard register. */
5912 if (GET_CODE (x) != REG
5913 || REGNO (x) < npi->min_reg
5914 || REGNO (x) >= npi->max_reg)
5917 regno = REGNO (x) - npi->min_reg;
5919 RESET_BIT (npi->nonnull_local[npi->current_block->index], regno);
5920 SET_BIT (npi->nonnull_killed[npi->current_block->index], regno);
5923 /* Do null-pointer check elimination for the registers indicated in
5924 NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
5925 they are not our responsibility to free. */
5928 delete_null_pointer_checks_1 (unsigned int *block_reg, sbitmap *nonnull_avin,
5929 sbitmap *nonnull_avout,
5930 struct null_pointer_info *npi)
5932 basic_block bb, current_block;
5933 sbitmap *nonnull_local = npi->nonnull_local;
5934 sbitmap *nonnull_killed = npi->nonnull_killed;
5935 int something_changed = 0;
5937 /* Compute local properties, nonnull and killed. A register will have
5938 the nonnull property if at the end of the current block its value is
5939 known to be nonnull. The killed property indicates that somewhere in
5940 the block any information we had about the register is killed.
5942 Note that a register can have both properties in a single block. That
5943 indicates that it's killed, then later in the block a new value is
5945 sbitmap_vector_zero (nonnull_local, last_basic_block);
5946 sbitmap_vector_zero (nonnull_killed, last_basic_block);
5948 FOR_EACH_BB (current_block)
5950 rtx insn, stop_insn;
5952 /* Set the current block for invalidate_nonnull_info. */
5953 npi->current_block = current_block;
5955 /* Scan each insn in the basic block looking for memory references and
5957 stop_insn = NEXT_INSN (BB_HEAD (current_block));
5958 for (insn = BB_HEAD (current_block);
5960 insn = NEXT_INSN (insn))
5965 /* Ignore anything that is not a normal insn. */
5966 if (! INSN_P (insn))
5969 /* Basically ignore anything that is not a simple SET. We do have
5970 to make sure to invalidate nonnull_local and set nonnull_killed
5971 for such insns though. */
5972 set = single_set (insn);
5975 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5979 /* See if we've got a usable memory load. We handle it first
5980 in case it uses its address register as a dest (which kills
5981 the nonnull property). */
5982 if (GET_CODE (SET_SRC (set)) == MEM
5983 && GET_CODE ((reg = XEXP (SET_SRC (set), 0))) == REG
5984 && REGNO (reg) >= npi->min_reg
5985 && REGNO (reg) < npi->max_reg)
5986 SET_BIT (nonnull_local[current_block->index],
5987 REGNO (reg) - npi->min_reg);
5989 /* Now invalidate stuff clobbered by this insn. */
5990 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5992 /* And handle stores, we do these last since any sets in INSN can
5993 not kill the nonnull property if it is derived from a MEM
5994 appearing in a SET_DEST. */
5995 if (GET_CODE (SET_DEST (set)) == MEM
5996 && GET_CODE ((reg = XEXP (SET_DEST (set), 0))) == REG
5997 && REGNO (reg) >= npi->min_reg
5998 && REGNO (reg) < npi->max_reg)
5999 SET_BIT (nonnull_local[current_block->index],
6000 REGNO (reg) - npi->min_reg);
6004 /* Now compute global properties based on the local properties. This
6005 is a classic global availability algorithm. */
6006 compute_available (nonnull_local, nonnull_killed,
6007 nonnull_avout, nonnull_avin);
6009 /* Now look at each bb and see if it ends with a compare of a value
6013 rtx last_insn = BB_END (bb);
6014 rtx condition, earliest;
6015 int compare_and_branch;
6017 /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
6018 since BLOCK_REG[BB] is zero if this block did not end with a
6019 comparison against zero, this condition works. */
6020 if (block_reg[bb->index] < npi->min_reg
6021 || block_reg[bb->index] >= npi->max_reg)
6024 /* LAST_INSN is a conditional jump. Get its condition. */
6025 condition = get_condition (last_insn, &earliest, false);
6027 /* If we can't determine the condition then skip. */
6031 /* Is the register known to have a nonzero value? */
6032 if (!TEST_BIT (nonnull_avout[bb->index], block_reg[bb->index] - npi->min_reg))
6035 /* Try to compute whether the compare/branch at the loop end is one or
6036 two instructions. */
6037 if (earliest == last_insn)
6038 compare_and_branch = 1;
6039 else if (earliest == prev_nonnote_insn (last_insn))
6040 compare_and_branch = 2;
6044 /* We know the register in this comparison is nonnull at exit from
6045 this block. We can optimize this comparison. */
6046 if (GET_CODE (condition) == NE)
6050 new_jump = emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn)),
6052 JUMP_LABEL (new_jump) = JUMP_LABEL (last_insn);
6053 LABEL_NUSES (JUMP_LABEL (new_jump))++;
6054 emit_barrier_after (new_jump);
6057 something_changed = 1;
6058 delete_insn (last_insn);
6059 if (compare_and_branch == 2)
6060 delete_insn (earliest);
6061 purge_dead_edges (bb);
6063 /* Don't check this block again. (Note that BB_END is
6064 invalid here; we deleted the last instruction in the
6066 block_reg[bb->index] = 0;
6069 return something_changed;
6072 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
6075 This is conceptually similar to global constant/copy propagation and
6076 classic global CSE (it even uses the same dataflow equations as cprop).
6078 If a register is used as memory address with the form (mem (reg)), then we
6079 know that REG can not be zero at that point in the program. Any instruction
6080 which sets REG "kills" this property.
6082 So, if every path leading to a conditional branch has an available memory
6083 reference of that form, then we know the register can not have the value
6084 zero at the conditional branch.
6086 So we merely need to compute the local properties and propagate that data
6087 around the cfg, then optimize where possible.
6089 We run this pass two times. Once before CSE, then again after CSE. This
6090 has proven to be the most profitable approach. It is rare for new
6091 optimization opportunities of this nature to appear after the first CSE
6094 This could probably be integrated with global cprop with a little work. */
6097 delete_null_pointer_checks (rtx f ATTRIBUTE_UNUSED)
6099 sbitmap *nonnull_avin, *nonnull_avout;
6100 unsigned int *block_reg;
6104 int max_reg = max_reg_num ();
6105 struct null_pointer_info npi;
6106 int something_changed = 0;
6108 /* If we have only a single block, or it is too expensive, give up. */
6109 if (n_basic_blocks <= 1
6110 || is_too_expensive (_ ("NULL pointer checks disabled")))
6113 /* We need four bitmaps, each with a bit for each register in each
6115 regs_per_pass = get_bitmap_width (4, last_basic_block, max_reg);
6117 /* Allocate bitmaps to hold local and global properties. */
6118 npi.nonnull_local = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
6119 npi.nonnull_killed = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
6120 nonnull_avin = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
6121 nonnull_avout = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
6123 /* Go through the basic blocks, seeing whether or not each block
6124 ends with a conditional branch whose condition is a comparison
6125 against zero. Record the register compared in BLOCK_REG. */
6126 block_reg = xcalloc (last_basic_block, sizeof (int));
6129 rtx last_insn = BB_END (bb);
6130 rtx condition, earliest, reg;
6132 /* We only want conditional branches. */
6133 if (GET_CODE (last_insn) != JUMP_INSN
6134 || !any_condjump_p (last_insn)
6135 || !onlyjump_p (last_insn))
6138 /* LAST_INSN is a conditional jump. Get its condition. */
6139 condition = get_condition (last_insn, &earliest, false);
6141 /* If we were unable to get the condition, or it is not an equality
6142 comparison against zero then there's nothing we can do. */
6144 || (GET_CODE (condition) != NE && GET_CODE (condition) != EQ)
6145 || GET_CODE (XEXP (condition, 1)) != CONST_INT
6146 || (XEXP (condition, 1)
6147 != CONST0_RTX (GET_MODE (XEXP (condition, 0)))))
6150 /* We must be checking a register against zero. */
6151 reg = XEXP (condition, 0);
6152 if (GET_CODE (reg) != REG)
6155 block_reg[bb->index] = REGNO (reg);
6158 /* Go through the algorithm for each block of registers. */
6159 for (reg = FIRST_PSEUDO_REGISTER; reg < max_reg; reg += regs_per_pass)
6162 npi.max_reg = MIN (reg + regs_per_pass, max_reg);
6163 something_changed |= delete_null_pointer_checks_1 (block_reg,
6169 /* Free the table of registers compared at the end of every block. */
6173 sbitmap_vector_free (npi.nonnull_local);
6174 sbitmap_vector_free (npi.nonnull_killed);
6175 sbitmap_vector_free (nonnull_avin);
6176 sbitmap_vector_free (nonnull_avout);
6178 return something_changed;
6181 /* Code Hoisting variables and subroutines. */
6183 /* Very busy expressions. */
6184 static sbitmap *hoist_vbein;
6185 static sbitmap *hoist_vbeout;
6187 /* Hoistable expressions. */
6188 static sbitmap *hoist_exprs;
6190 /* ??? We could compute post dominators and run this algorithm in
6191 reverse to perform tail merging, doing so would probably be
6192 more effective than the tail merging code in jump.c.
6194 It's unclear if tail merging could be run in parallel with
6195 code hoisting. It would be nice. */
6197 /* Allocate vars used for code hoisting analysis. */
6200 alloc_code_hoist_mem (int n_blocks, int n_exprs)
6202 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
6203 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
6204 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
6206 hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
6207 hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
6208 hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
6209 transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
6212 /* Free vars used for code hoisting analysis. */
6215 free_code_hoist_mem (void)
6217 sbitmap_vector_free (antloc);
6218 sbitmap_vector_free (transp);
6219 sbitmap_vector_free (comp);
6221 sbitmap_vector_free (hoist_vbein);
6222 sbitmap_vector_free (hoist_vbeout);
6223 sbitmap_vector_free (hoist_exprs);
6224 sbitmap_vector_free (transpout);
6226 free_dominance_info (CDI_DOMINATORS);
6229 /* Compute the very busy expressions at entry/exit from each block.
6231 An expression is very busy if all paths from a given point
6232 compute the expression. */
6235 compute_code_hoist_vbeinout (void)
6237 int changed, passes;
6240 sbitmap_vector_zero (hoist_vbeout, last_basic_block);
6241 sbitmap_vector_zero (hoist_vbein, last_basic_block);
6250 /* We scan the blocks in the reverse order to speed up
6252 FOR_EACH_BB_REVERSE (bb)
6254 changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index], antloc[bb->index],
6255 hoist_vbeout[bb->index], transp[bb->index]);
6256 if (bb->next_bb != EXIT_BLOCK_PTR)
6257 sbitmap_intersection_of_succs (hoist_vbeout[bb->index], hoist_vbein, bb->index);
6264 fprintf (gcse_file, "hoisting vbeinout computation: %d passes\n", passes);
6267 /* Top level routine to do the dataflow analysis needed by code hoisting. */
6270 compute_code_hoist_data (void)
6272 compute_local_properties (transp, comp, antloc, &expr_hash_table);
6273 compute_transpout ();
6274 compute_code_hoist_vbeinout ();
6275 calculate_dominance_info (CDI_DOMINATORS);
6277 fprintf (gcse_file, "\n");
6280 /* Determine if the expression identified by EXPR_INDEX would
6281 reach BB unimpared if it was placed at the end of EXPR_BB.
6283 It's unclear exactly what Muchnick meant by "unimpared". It seems
6284 to me that the expression must either be computed or transparent in
6285 *every* block in the path(s) from EXPR_BB to BB. Any other definition
6286 would allow the expression to be hoisted out of loops, even if
6287 the expression wasn't a loop invariant.
6289 Contrast this to reachability for PRE where an expression is
6290 considered reachable if *any* path reaches instead of *all*
6294 hoist_expr_reaches_here_p (basic_block expr_bb, int expr_index, basic_block bb, char *visited)
6297 int visited_allocated_locally = 0;
6300 if (visited == NULL)
6302 visited_allocated_locally = 1;
6303 visited = xcalloc (last_basic_block, 1);
6306 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
6308 basic_block pred_bb = pred->src;
6310 if (pred->src == ENTRY_BLOCK_PTR)
6312 else if (pred_bb == expr_bb)
6314 else if (visited[pred_bb->index])
6317 /* Does this predecessor generate this expression? */
6318 else if (TEST_BIT (comp[pred_bb->index], expr_index))
6320 else if (! TEST_BIT (transp[pred_bb->index], expr_index))
6326 visited[pred_bb->index] = 1;
6327 if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
6332 if (visited_allocated_locally)
6335 return (pred == NULL);
6338 /* Actually perform code hoisting. */
6343 basic_block bb, dominated;
6345 unsigned int domby_len;
6347 struct expr **index_map;
6350 sbitmap_vector_zero (hoist_exprs, last_basic_block);
6352 /* Compute a mapping from expression number (`bitmap_index') to
6353 hash table entry. */
6355 index_map = xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
6356 for (i = 0; i < expr_hash_table.size; i++)
6357 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
6358 index_map[expr->bitmap_index] = expr;
6360 /* Walk over each basic block looking for potentially hoistable
6361 expressions, nothing gets hoisted from the entry block. */
6365 int insn_inserted_p;
6367 domby_len = get_dominated_by (CDI_DOMINATORS, bb, &domby);
6368 /* Examine each expression that is very busy at the exit of this
6369 block. These are the potentially hoistable expressions. */
6370 for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++)
6374 if (TEST_BIT (hoist_vbeout[bb->index], i)
6375 && TEST_BIT (transpout[bb->index], i))
6377 /* We've found a potentially hoistable expression, now
6378 we look at every block BB dominates to see if it
6379 computes the expression. */
6380 for (j = 0; j < domby_len; j++)
6382 dominated = domby[j];
6383 /* Ignore self dominance. */
6384 if (bb == dominated)
6386 /* We've found a dominated block, now see if it computes
6387 the busy expression and whether or not moving that
6388 expression to the "beginning" of that block is safe. */
6389 if (!TEST_BIT (antloc[dominated->index], i))
6392 /* Note if the expression would reach the dominated block
6393 unimpared if it was placed at the end of BB.
6395 Keep track of how many times this expression is hoistable
6396 from a dominated block into BB. */
6397 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
6401 /* If we found more than one hoistable occurrence of this
6402 expression, then note it in the bitmap of expressions to
6403 hoist. It makes no sense to hoist things which are computed
6404 in only one BB, and doing so tends to pessimize register
6405 allocation. One could increase this value to try harder
6406 to avoid any possible code expansion due to register
6407 allocation issues; however experiments have shown that
6408 the vast majority of hoistable expressions are only movable
6409 from two successors, so raising this threshold is likely
6410 to nullify any benefit we get from code hoisting. */
6413 SET_BIT (hoist_exprs[bb->index], i);
6418 /* If we found nothing to hoist, then quit now. */
6425 /* Loop over all the hoistable expressions. */
6426 for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++)
6428 /* We want to insert the expression into BB only once, so
6429 note when we've inserted it. */
6430 insn_inserted_p = 0;
6432 /* These tests should be the same as the tests above. */
6433 if (TEST_BIT (hoist_vbeout[bb->index], i))
6435 /* We've found a potentially hoistable expression, now
6436 we look at every block BB dominates to see if it
6437 computes the expression. */
6438 for (j = 0; j < domby_len; j++)
6440 dominated = domby[j];
6441 /* Ignore self dominance. */
6442 if (bb == dominated)
6445 /* We've found a dominated block, now see if it computes
6446 the busy expression and whether or not moving that
6447 expression to the "beginning" of that block is safe. */
6448 if (!TEST_BIT (antloc[dominated->index], i))
6451 /* The expression is computed in the dominated block and
6452 it would be safe to compute it at the start of the
6453 dominated block. Now we have to determine if the
6454 expression would reach the dominated block if it was
6455 placed at the end of BB. */
6456 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
6458 struct expr *expr = index_map[i];
6459 struct occr *occr = expr->antic_occr;
6463 /* Find the right occurrence of this expression. */
6464 while (BLOCK_FOR_INSN (occr->insn) != dominated && occr)
6467 /* Should never happen. */
6473 set = single_set (insn);
6477 /* Create a pseudo-reg to store the result of reaching
6478 expressions into. Get the mode for the new pseudo
6479 from the mode of the original destination pseudo. */
6480 if (expr->reaching_reg == NULL)
6482 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
6484 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
6486 occr->deleted_p = 1;
6487 if (!insn_inserted_p)
6489 insert_insn_end_bb (index_map[i], bb, 0);
6490 insn_inserted_p = 1;
6502 /* Top level routine to perform one code hoisting (aka unification) pass
6504 Return nonzero if a change was made. */
6507 one_code_hoisting_pass (void)
6511 alloc_hash_table (max_cuid, &expr_hash_table, 0);
6512 compute_hash_table (&expr_hash_table);
6514 dump_hash_table (gcse_file, "Code Hosting Expressions", &expr_hash_table);
6516 if (expr_hash_table.n_elems > 0)
6518 alloc_code_hoist_mem (last_basic_block, expr_hash_table.n_elems);
6519 compute_code_hoist_data ();
6521 free_code_hoist_mem ();
6524 free_hash_table (&expr_hash_table);
6529 /* Here we provide the things required to do store motion towards
6530 the exit. In order for this to be effective, gcse also needed to
6531 be taught how to move a load when it is kill only by a store to itself.
6536 void foo(float scale)
6538 for (i=0; i<10; i++)
6542 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
6543 the load out since its live around the loop, and stored at the bottom
6546 The 'Load Motion' referred to and implemented in this file is
6547 an enhancement to gcse which when using edge based lcm, recognizes
6548 this situation and allows gcse to move the load out of the loop.
6550 Once gcse has hoisted the load, store motion can then push this
6551 load towards the exit, and we end up with no loads or stores of 'i'
6554 /* This will search the ldst list for a matching expression. If it
6555 doesn't find one, we create one and initialize it. */
6557 static struct ls_expr *
6560 int do_not_record_p = 0;
6561 struct ls_expr * ptr;
6564 hash = hash_expr_1 (x, GET_MODE (x), & do_not_record_p);
6566 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6567 if (ptr->hash_index == hash && expr_equiv_p (ptr->pattern, x))
6570 ptr = xmalloc (sizeof (struct ls_expr));
6572 ptr->next = pre_ldst_mems;
6575 ptr->pattern_regs = NULL_RTX;
6576 ptr->loads = NULL_RTX;
6577 ptr->stores = NULL_RTX;
6578 ptr->reaching_reg = NULL_RTX;
6581 ptr->hash_index = hash;
6582 pre_ldst_mems = ptr;
6587 /* Free up an individual ldst entry. */
6590 free_ldst_entry (struct ls_expr * ptr)
6592 free_INSN_LIST_list (& ptr->loads);
6593 free_INSN_LIST_list (& ptr->stores);
6598 /* Free up all memory associated with the ldst list. */
6601 free_ldst_mems (void)
6603 while (pre_ldst_mems)
6605 struct ls_expr * tmp = pre_ldst_mems;
6607 pre_ldst_mems = pre_ldst_mems->next;
6609 free_ldst_entry (tmp);
6612 pre_ldst_mems = NULL;
6615 /* Dump debugging info about the ldst list. */
6618 print_ldst_list (FILE * file)
6620 struct ls_expr * ptr;
6622 fprintf (file, "LDST list: \n");
6624 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
6626 fprintf (file, " Pattern (%3d): ", ptr->index);
6628 print_rtl (file, ptr->pattern);
6630 fprintf (file, "\n Loads : ");
6633 print_rtl (file, ptr->loads);
6635 fprintf (file, "(nil)");
6637 fprintf (file, "\n Stores : ");
6640 print_rtl (file, ptr->stores);
6642 fprintf (file, "(nil)");
6644 fprintf (file, "\n\n");
6647 fprintf (file, "\n");
6650 /* Returns 1 if X is in the list of ldst only expressions. */
6652 static struct ls_expr *
6653 find_rtx_in_ldst (rtx x)
6655 struct ls_expr * ptr;
6657 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6658 if (expr_equiv_p (ptr->pattern, x) && ! ptr->invalid)
6664 /* Assign each element of the list of mems a monotonically increasing value. */
6667 enumerate_ldsts (void)
6669 struct ls_expr * ptr;
6672 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6678 /* Return first item in the list. */
6680 static inline struct ls_expr *
6681 first_ls_expr (void)
6683 return pre_ldst_mems;
6686 /* Return the next item in the list after the specified one. */
6688 static inline struct ls_expr *
6689 next_ls_expr (struct ls_expr * ptr)
6694 /* Load Motion for loads which only kill themselves. */
6696 /* Return true if x is a simple MEM operation, with no registers or
6697 side effects. These are the types of loads we consider for the
6698 ld_motion list, otherwise we let the usual aliasing take care of it. */
6703 if (GET_CODE (x) != MEM)
6706 if (MEM_VOLATILE_P (x))
6709 if (GET_MODE (x) == BLKmode)
6712 /* If we are handling exceptions, we must be careful with memory references
6713 that may trap. If we are not, the behavior is undefined, so we may just
6715 if (flag_non_call_exceptions && may_trap_p (x))
6718 if (side_effects_p (x))
6721 /* Do not consider function arguments passed on stack. */
6722 if (reg_mentioned_p (stack_pointer_rtx, x))
6725 if (flag_float_store && FLOAT_MODE_P (GET_MODE (x)))
6731 /* Make sure there isn't a buried reference in this pattern anywhere.
6732 If there is, invalidate the entry for it since we're not capable
6733 of fixing it up just yet.. We have to be sure we know about ALL
6734 loads since the aliasing code will allow all entries in the
6735 ld_motion list to not-alias itself. If we miss a load, we will get
6736 the wrong value since gcse might common it and we won't know to
6740 invalidate_any_buried_refs (rtx x)
6744 struct ls_expr * ptr;
6746 /* Invalidate it in the list. */
6747 if (GET_CODE (x) == MEM && simple_mem (x))
6749 ptr = ldst_entry (x);
6753 /* Recursively process the insn. */
6754 fmt = GET_RTX_FORMAT (GET_CODE (x));
6756 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
6759 invalidate_any_buried_refs (XEXP (x, i));
6760 else if (fmt[i] == 'E')
6761 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6762 invalidate_any_buried_refs (XVECEXP (x, i, j));
6766 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
6767 being defined as MEM loads and stores to symbols, with no side effects
6768 and no registers in the expression. For a MEM destination, we also
6769 check that the insn is still valid if we replace the destination with a
6770 REG, as is done in update_ld_motion_stores. If there are any uses/defs
6771 which don't match this criteria, they are invalidated and trimmed out
6775 compute_ld_motion_mems (void)
6777 struct ls_expr * ptr;
6781 pre_ldst_mems = NULL;
6785 for (insn = BB_HEAD (bb);
6786 insn && insn != NEXT_INSN (BB_END (bb));
6787 insn = NEXT_INSN (insn))
6791 if (GET_CODE (PATTERN (insn)) == SET)
6793 rtx src = SET_SRC (PATTERN (insn));
6794 rtx dest = SET_DEST (PATTERN (insn));
6796 /* Check for a simple LOAD... */
6797 if (GET_CODE (src) == MEM && simple_mem (src))
6799 ptr = ldst_entry (src);
6800 if (GET_CODE (dest) == REG)
6801 ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
6807 /* Make sure there isn't a buried load somewhere. */
6808 invalidate_any_buried_refs (src);
6811 /* Check for stores. Don't worry about aliased ones, they
6812 will block any movement we might do later. We only care
6813 about this exact pattern since those are the only
6814 circumstance that we will ignore the aliasing info. */
6815 if (GET_CODE (dest) == MEM && simple_mem (dest))
6817 ptr = ldst_entry (dest);
6819 if (GET_CODE (src) != MEM
6820 && GET_CODE (src) != ASM_OPERANDS
6821 /* Check for REG manually since want_to_gcse_p
6822 returns 0 for all REGs. */
6823 && (REG_P (src) || want_to_gcse_p (src)))
6824 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
6830 invalidate_any_buried_refs (PATTERN (insn));
6836 /* Remove any references that have been either invalidated or are not in the
6837 expression list for pre gcse. */
6840 trim_ld_motion_mems (void)
6842 struct ls_expr * * last = & pre_ldst_mems;
6843 struct ls_expr * ptr = pre_ldst_mems;
6849 /* Delete if entry has been made invalid. */
6852 /* Delete if we cannot find this mem in the expression list. */
6853 unsigned int hash = ptr->hash_index % expr_hash_table.size;
6855 for (expr = expr_hash_table.table[hash];
6857 expr = expr->next_same_hash)
6858 if (expr_equiv_p (expr->expr, ptr->pattern))
6862 expr = (struct expr *) 0;
6866 /* Set the expression field if we are keeping it. */
6874 free_ldst_entry (ptr);
6879 /* Show the world what we've found. */
6880 if (gcse_file && pre_ldst_mems != NULL)
6881 print_ldst_list (gcse_file);
6884 /* This routine will take an expression which we are replacing with
6885 a reaching register, and update any stores that are needed if
6886 that expression is in the ld_motion list. Stores are updated by
6887 copying their SRC to the reaching register, and then storing
6888 the reaching register into the store location. These keeps the
6889 correct value in the reaching register for the loads. */
6892 update_ld_motion_stores (struct expr * expr)
6894 struct ls_expr * mem_ptr;
6896 if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
6898 /* We can try to find just the REACHED stores, but is shouldn't
6899 matter to set the reaching reg everywhere... some might be
6900 dead and should be eliminated later. */
6902 /* We replace (set mem expr) with (set reg expr) (set mem reg)
6903 where reg is the reaching reg used in the load. We checked in
6904 compute_ld_motion_mems that we can replace (set mem expr) with
6905 (set reg expr) in that insn. */
6906 rtx list = mem_ptr->stores;
6908 for ( ; list != NULL_RTX; list = XEXP (list, 1))
6910 rtx insn = XEXP (list, 0);
6911 rtx pat = PATTERN (insn);
6912 rtx src = SET_SRC (pat);
6913 rtx reg = expr->reaching_reg;
6916 /* If we've already copied it, continue. */
6917 if (expr->reaching_reg == src)
6922 fprintf (gcse_file, "PRE: store updated with reaching reg ");
6923 print_rtl (gcse_file, expr->reaching_reg);
6924 fprintf (gcse_file, ":\n ");
6925 print_inline_rtx (gcse_file, insn, 8);
6926 fprintf (gcse_file, "\n");
6929 copy = gen_move_insn ( reg, copy_rtx (SET_SRC (pat)));
6930 new = emit_insn_before (copy, insn);
6931 record_one_set (REGNO (reg), new);
6932 SET_SRC (pat) = reg;
6934 /* un-recognize this pattern since it's probably different now. */
6935 INSN_CODE (insn) = -1;
6936 gcse_create_count++;
6941 /* Store motion code. */
6943 #define ANTIC_STORE_LIST(x) ((x)->loads)
6944 #define AVAIL_STORE_LIST(x) ((x)->stores)
6945 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
6947 /* This is used to communicate the target bitvector we want to use in the
6948 reg_set_info routine when called via the note_stores mechanism. */
6949 static int * regvec;
6951 /* And current insn, for the same routine. */
6952 static rtx compute_store_table_current_insn;
6954 /* Used in computing the reverse edge graph bit vectors. */
6955 static sbitmap * st_antloc;
6957 /* Global holding the number of store expressions we are dealing with. */
6958 static int num_stores;
6960 /* Checks to set if we need to mark a register set. Called from
6964 reg_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED,
6967 sbitmap bb_reg = data;
6969 if (GET_CODE (dest) == SUBREG)
6970 dest = SUBREG_REG (dest);
6972 if (GET_CODE (dest) == REG)
6974 regvec[REGNO (dest)] = INSN_UID (compute_store_table_current_insn);
6976 SET_BIT (bb_reg, REGNO (dest));
6980 /* Clear any mark that says that this insn sets dest. Called from
6984 reg_clear_last_set (rtx dest, rtx setter ATTRIBUTE_UNUSED,
6987 int *dead_vec = data;
6989 if (GET_CODE (dest) == SUBREG)
6990 dest = SUBREG_REG (dest);
6992 if (GET_CODE (dest) == REG &&
6993 dead_vec[REGNO (dest)] == INSN_UID (compute_store_table_current_insn))
6994 dead_vec[REGNO (dest)] = 0;
6997 /* Return zero if some of the registers in list X are killed
6998 due to set of registers in bitmap REGS_SET. */
7001 store_ops_ok (rtx x, int *regs_set)
7005 for (; x; x = XEXP (x, 1))
7008 if (regs_set[REGNO(reg)])
7015 /* Returns a list of registers mentioned in X. */
7017 extract_mentioned_regs (rtx x)
7019 return extract_mentioned_regs_helper (x, NULL_RTX);
7022 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
7025 extract_mentioned_regs_helper (rtx x, rtx accum)
7031 /* Repeat is used to turn tail-recursion into iteration. */
7037 code = GET_CODE (x);
7041 return alloc_EXPR_LIST (0, x, accum);
7051 /* We do not run this function with arguments having side effects. */
7070 i = GET_RTX_LENGTH (code) - 1;
7071 fmt = GET_RTX_FORMAT (code);
7077 rtx tem = XEXP (x, i);
7079 /* If we are about to do the last recursive call
7080 needed at this level, change it into iteration. */
7087 accum = extract_mentioned_regs_helper (tem, accum);
7089 else if (fmt[i] == 'E')
7093 for (j = 0; j < XVECLEN (x, i); j++)
7094 accum = extract_mentioned_regs_helper (XVECEXP (x, i, j), accum);
7101 /* Determine whether INSN is MEM store pattern that we will consider moving.
7102 REGS_SET_BEFORE is bitmap of registers set before (and including) the
7103 current insn, REGS_SET_AFTER is bitmap of registers set after (and
7104 including) the insn in this basic block. We must be passing through BB from
7105 head to end, as we are using this fact to speed things up.
7107 The results are stored this way:
7109 -- the first anticipatable expression is added into ANTIC_STORE_LIST
7110 -- if the processed expression is not anticipatable, NULL_RTX is added
7111 there instead, so that we can use it as indicator that no further
7112 expression of this type may be anticipatable
7113 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
7114 consequently, all of them but this head are dead and may be deleted.
7115 -- if the expression is not available, the insn due to that it fails to be
7116 available is stored in reaching_reg.
7118 The things are complicated a bit by fact that there already may be stores
7119 to the same MEM from other blocks; also caller must take care of the
7120 necessary cleanup of the temporary markers after end of the basic block.
7124 find_moveable_store (rtx insn, int *regs_set_before, int *regs_set_after)
7126 struct ls_expr * ptr;
7128 int check_anticipatable, check_available;
7129 basic_block bb = BLOCK_FOR_INSN (insn);
7131 set = single_set (insn);
7135 dest = SET_DEST (set);
7137 if (GET_CODE (dest) != MEM || MEM_VOLATILE_P (dest)
7138 || GET_MODE (dest) == BLKmode)
7141 if (side_effects_p (dest))
7144 /* If we are handling exceptions, we must be careful with memory references
7145 that may trap. If we are not, the behavior is undefined, so we may just
7147 if (flag_non_call_exceptions && may_trap_p (dest))
7150 ptr = ldst_entry (dest);
7151 if (!ptr->pattern_regs)
7152 ptr->pattern_regs = extract_mentioned_regs (dest);
7154 /* Do not check for anticipatability if we either found one anticipatable
7155 store already, or tested for one and found out that it was killed. */
7156 check_anticipatable = 0;
7157 if (!ANTIC_STORE_LIST (ptr))
7158 check_anticipatable = 1;
7161 tmp = XEXP (ANTIC_STORE_LIST (ptr), 0);
7163 && BLOCK_FOR_INSN (tmp) != bb)
7164 check_anticipatable = 1;
7166 if (check_anticipatable)
7168 if (store_killed_before (dest, ptr->pattern_regs, insn, bb, regs_set_before))
7172 ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (tmp,
7173 ANTIC_STORE_LIST (ptr));
7176 /* It is not necessary to check whether store is available if we did
7177 it successfully before; if we failed before, do not bother to check
7178 until we reach the insn that caused us to fail. */
7179 check_available = 0;
7180 if (!AVAIL_STORE_LIST (ptr))
7181 check_available = 1;
7184 tmp = XEXP (AVAIL_STORE_LIST (ptr), 0);
7185 if (BLOCK_FOR_INSN (tmp) != bb)
7186 check_available = 1;
7188 if (check_available)
7190 /* Check that we have already reached the insn at that the check
7191 failed last time. */
7192 if (LAST_AVAIL_CHECK_FAILURE (ptr))
7194 for (tmp = BB_END (bb);
7195 tmp != insn && tmp != LAST_AVAIL_CHECK_FAILURE (ptr);
7196 tmp = PREV_INSN (tmp))
7199 check_available = 0;
7202 check_available = store_killed_after (dest, ptr->pattern_regs, insn,
7204 &LAST_AVAIL_CHECK_FAILURE (ptr));
7206 if (!check_available)
7207 AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn, AVAIL_STORE_LIST (ptr));
7210 /* Find available and anticipatable stores. */
7213 compute_store_table (void)
7219 int *last_set_in, *already_set;
7220 struct ls_expr * ptr, **prev_next_ptr_ptr;
7222 max_gcse_regno = max_reg_num ();
7224 reg_set_in_block = sbitmap_vector_alloc (last_basic_block,
7226 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
7228 last_set_in = xcalloc (max_gcse_regno, sizeof (int));
7229 already_set = xmalloc (sizeof (int) * max_gcse_regno);
7231 /* Find all the stores we care about. */
7234 /* First compute the registers set in this block. */
7235 regvec = last_set_in;
7237 for (insn = BB_HEAD (bb);
7238 insn != NEXT_INSN (BB_END (bb));
7239 insn = NEXT_INSN (insn))
7241 if (! INSN_P (insn))
7244 if (GET_CODE (insn) == CALL_INSN)
7246 bool clobbers_all = false;
7247 #ifdef NON_SAVING_SETJMP
7248 if (NON_SAVING_SETJMP
7249 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
7250 clobbers_all = true;
7253 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
7255 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
7257 last_set_in[regno] = INSN_UID (insn);
7258 SET_BIT (reg_set_in_block[bb->index], regno);
7262 pat = PATTERN (insn);
7263 compute_store_table_current_insn = insn;
7264 note_stores (pat, reg_set_info, reg_set_in_block[bb->index]);
7267 /* Now find the stores. */
7268 memset (already_set, 0, sizeof (int) * max_gcse_regno);
7269 regvec = already_set;
7270 for (insn = BB_HEAD (bb);
7271 insn != NEXT_INSN (BB_END (bb));
7272 insn = NEXT_INSN (insn))
7274 if (! INSN_P (insn))
7277 if (GET_CODE (insn) == CALL_INSN)
7279 bool clobbers_all = false;
7280 #ifdef NON_SAVING_SETJMP
7281 if (NON_SAVING_SETJMP
7282 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
7283 clobbers_all = true;
7286 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
7288 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
7289 already_set[regno] = 1;
7292 pat = PATTERN (insn);
7293 note_stores (pat, reg_set_info, NULL);
7295 /* Now that we've marked regs, look for stores. */
7296 find_moveable_store (insn, already_set, last_set_in);
7298 /* Unmark regs that are no longer set. */
7299 compute_store_table_current_insn = insn;
7300 note_stores (pat, reg_clear_last_set, last_set_in);
7301 if (GET_CODE (insn) == CALL_INSN)
7303 bool clobbers_all = false;
7304 #ifdef NON_SAVING_SETJMP
7305 if (NON_SAVING_SETJMP
7306 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
7307 clobbers_all = true;
7310 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
7312 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
7313 && last_set_in[regno] == INSN_UID (insn))
7314 last_set_in[regno] = 0;
7318 #ifdef ENABLE_CHECKING
7319 /* last_set_in should now be all-zero. */
7320 for (regno = 0; regno < max_gcse_regno; regno++)
7321 if (last_set_in[regno] != 0)
7325 /* Clear temporary marks. */
7326 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7328 LAST_AVAIL_CHECK_FAILURE(ptr) = NULL_RTX;
7329 if (ANTIC_STORE_LIST (ptr)
7330 && (tmp = XEXP (ANTIC_STORE_LIST (ptr), 0)) == NULL_RTX)
7331 ANTIC_STORE_LIST (ptr) = XEXP (ANTIC_STORE_LIST (ptr), 1);
7335 /* Remove the stores that are not available anywhere, as there will
7336 be no opportunity to optimize them. */
7337 for (ptr = pre_ldst_mems, prev_next_ptr_ptr = &pre_ldst_mems;
7339 ptr = *prev_next_ptr_ptr)
7341 if (!AVAIL_STORE_LIST (ptr))
7343 *prev_next_ptr_ptr = ptr->next;
7344 free_ldst_entry (ptr);
7347 prev_next_ptr_ptr = &ptr->next;
7350 ret = enumerate_ldsts ();
7354 fprintf (gcse_file, "ST_avail and ST_antic (shown under loads..)\n");
7355 print_ldst_list (gcse_file);
7363 /* Check to see if the load X is aliased with STORE_PATTERN.
7364 AFTER is true if we are checking the case when STORE_PATTERN occurs
7368 load_kills_store (rtx x, rtx store_pattern, int after)
7371 return anti_dependence (x, store_pattern);
7373 return true_dependence (store_pattern, GET_MODE (store_pattern), x,
7377 /* Go through the entire insn X, looking for any loads which might alias
7378 STORE_PATTERN. Return true if found.
7379 AFTER is true if we are checking the case when STORE_PATTERN occurs
7380 after the insn X. */
7383 find_loads (rtx x, rtx store_pattern, int after)
7392 if (GET_CODE (x) == SET)
7395 if (GET_CODE (x) == MEM)
7397 if (load_kills_store (x, store_pattern, after))
7401 /* Recursively process the insn. */
7402 fmt = GET_RTX_FORMAT (GET_CODE (x));
7404 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
7407 ret |= find_loads (XEXP (x, i), store_pattern, after);
7408 else if (fmt[i] == 'E')
7409 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
7410 ret |= find_loads (XVECEXP (x, i, j), store_pattern, after);
7415 /* Check if INSN kills the store pattern X (is aliased with it).
7416 AFTER is true if we are checking the case when store X occurs
7417 after the insn. Return true if it it does. */
7420 store_killed_in_insn (rtx x, rtx x_regs, rtx insn, int after)
7422 rtx reg, base, note;
7427 if (GET_CODE (insn) == CALL_INSN)
7429 /* A normal or pure call might read from pattern,
7430 but a const call will not. */
7431 if (! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn))
7434 /* But even a const call reads its parameters. Check whether the
7435 base of some of registers used in mem is stack pointer. */
7436 for (reg = x_regs; reg; reg = XEXP (reg, 1))
7438 base = find_base_term (XEXP (reg, 0));
7440 || (GET_CODE (base) == ADDRESS
7441 && GET_MODE (base) == Pmode
7442 && XEXP (base, 0) == stack_pointer_rtx))
7449 if (GET_CODE (PATTERN (insn)) == SET)
7451 rtx pat = PATTERN (insn);
7452 rtx dest = SET_DEST (pat);
7454 if (GET_CODE (dest) == SIGN_EXTRACT
7455 || GET_CODE (dest) == ZERO_EXTRACT)
7456 dest = XEXP (dest, 0);
7458 /* Check for memory stores to aliased objects. */
7459 if (GET_CODE (dest) == MEM
7460 && !expr_equiv_p (dest, x))
7464 if (output_dependence (dest, x))
7469 if (output_dependence (x, dest))
7473 if (find_loads (SET_SRC (pat), x, after))
7476 else if (find_loads (PATTERN (insn), x, after))
7479 /* If this insn has a REG_EQUAL or REG_EQUIV note referencing a memory
7480 location aliased with X, then this insn kills X. */
7481 note = find_reg_equal_equiv_note (insn);
7484 note = XEXP (note, 0);
7486 /* However, if the note represents a must alias rather than a may
7487 alias relationship, then it does not kill X. */
7488 if (expr_equiv_p (note, x))
7491 /* See if there are any aliased loads in the note. */
7492 return find_loads (note, x, after);
7495 /* Returns true if the expression X is loaded or clobbered on or after INSN
7496 within basic block BB. REGS_SET_AFTER is bitmap of registers set in
7497 or after the insn. X_REGS is list of registers mentioned in X. If the store
7498 is killed, return the last insn in that it occurs in FAIL_INSN. */
7501 store_killed_after (rtx x, rtx x_regs, rtx insn, basic_block bb,
7502 int *regs_set_after, rtx *fail_insn)
7504 rtx last = BB_END (bb), act;
7506 if (!store_ops_ok (x_regs, regs_set_after))
7508 /* We do not know where it will happen. */
7510 *fail_insn = NULL_RTX;
7514 /* Scan from the end, so that fail_insn is determined correctly. */
7515 for (act = last; act != PREV_INSN (insn); act = PREV_INSN (act))
7516 if (store_killed_in_insn (x, x_regs, act, false))
7526 /* Returns true if the expression X is loaded or clobbered on or before INSN
7527 within basic block BB. X_REGS is list of registers mentioned in X.
7528 REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
7530 store_killed_before (rtx x, rtx x_regs, rtx insn, basic_block bb,
7531 int *regs_set_before)
7533 rtx first = BB_HEAD (bb);
7535 if (!store_ops_ok (x_regs, regs_set_before))
7538 for ( ; insn != PREV_INSN (first); insn = PREV_INSN (insn))
7539 if (store_killed_in_insn (x, x_regs, insn, true))
7545 /* Fill in available, anticipatable, transparent and kill vectors in
7546 STORE_DATA, based on lists of available and anticipatable stores. */
7548 build_store_vectors (void)
7551 int *regs_set_in_block;
7553 struct ls_expr * ptr;
7556 /* Build the gen_vector. This is any store in the table which is not killed
7557 by aliasing later in its block. */
7558 ae_gen = sbitmap_vector_alloc (last_basic_block, num_stores);
7559 sbitmap_vector_zero (ae_gen, last_basic_block);
7561 st_antloc = sbitmap_vector_alloc (last_basic_block, num_stores);
7562 sbitmap_vector_zero (st_antloc, last_basic_block);
7564 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7566 for (st = AVAIL_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
7568 insn = XEXP (st, 0);
7569 bb = BLOCK_FOR_INSN (insn);
7571 /* If we've already seen an available expression in this block,
7572 we can delete this one (It occurs earlier in the block). We'll
7573 copy the SRC expression to an unused register in case there
7574 are any side effects. */
7575 if (TEST_BIT (ae_gen[bb->index], ptr->index))
7577 rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
7579 fprintf (gcse_file, "Removing redundant store:\n");
7580 replace_store_insn (r, XEXP (st, 0), bb, ptr);
7583 SET_BIT (ae_gen[bb->index], ptr->index);
7586 for (st = ANTIC_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
7588 insn = XEXP (st, 0);
7589 bb = BLOCK_FOR_INSN (insn);
7590 SET_BIT (st_antloc[bb->index], ptr->index);
7594 ae_kill = sbitmap_vector_alloc (last_basic_block, num_stores);
7595 sbitmap_vector_zero (ae_kill, last_basic_block);
7597 transp = sbitmap_vector_alloc (last_basic_block, num_stores);
7598 sbitmap_vector_zero (transp, last_basic_block);
7599 regs_set_in_block = xmalloc (sizeof (int) * max_gcse_regno);
7603 for (regno = 0; regno < max_gcse_regno; regno++)
7604 regs_set_in_block[regno] = TEST_BIT (reg_set_in_block[bb->index], regno);
7606 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7608 if (store_killed_after (ptr->pattern, ptr->pattern_regs, BB_HEAD (bb),
7609 bb, regs_set_in_block, NULL))
7611 /* It should not be necessary to consider the expression
7612 killed if it is both anticipatable and available. */
7613 if (!TEST_BIT (st_antloc[bb->index], ptr->index)
7614 || !TEST_BIT (ae_gen[bb->index], ptr->index))
7615 SET_BIT (ae_kill[bb->index], ptr->index);
7618 SET_BIT (transp[bb->index], ptr->index);
7622 free (regs_set_in_block);
7626 dump_sbitmap_vector (gcse_file, "st_antloc", "", st_antloc, last_basic_block);
7627 dump_sbitmap_vector (gcse_file, "st_kill", "", ae_kill, last_basic_block);
7628 dump_sbitmap_vector (gcse_file, "Transpt", "", transp, last_basic_block);
7629 dump_sbitmap_vector (gcse_file, "st_avloc", "", ae_gen, last_basic_block);
7633 /* Insert an instruction at the beginning of a basic block, and update
7634 the BB_HEAD if needed. */
7637 insert_insn_start_bb (rtx insn, basic_block bb)
7639 /* Insert at start of successor block. */
7640 rtx prev = PREV_INSN (BB_HEAD (bb));
7641 rtx before = BB_HEAD (bb);
7644 if (GET_CODE (before) != CODE_LABEL
7645 && (GET_CODE (before) != NOTE
7646 || NOTE_LINE_NUMBER (before) != NOTE_INSN_BASIC_BLOCK))
7649 if (prev == BB_END (bb))
7651 before = NEXT_INSN (before);
7654 insn = emit_insn_after (insn, prev);
7658 fprintf (gcse_file, "STORE_MOTION insert store at start of BB %d:\n",
7660 print_inline_rtx (gcse_file, insn, 6);
7661 fprintf (gcse_file, "\n");
7665 /* This routine will insert a store on an edge. EXPR is the ldst entry for
7666 the memory reference, and E is the edge to insert it on. Returns nonzero
7667 if an edge insertion was performed. */
7670 insert_store (struct ls_expr * expr, edge e)
7676 /* We did all the deleted before this insert, so if we didn't delete a
7677 store, then we haven't set the reaching reg yet either. */
7678 if (expr->reaching_reg == NULL_RTX)
7681 if (e->flags & EDGE_FAKE)
7684 reg = expr->reaching_reg;
7685 insn = gen_move_insn (copy_rtx (expr->pattern), reg);
7687 /* If we are inserting this expression on ALL predecessor edges of a BB,
7688 insert it at the start of the BB, and reset the insert bits on the other
7689 edges so we don't try to insert it on the other edges. */
7691 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
7692 if (!(tmp->flags & EDGE_FAKE))
7694 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
7695 if (index == EDGE_INDEX_NO_EDGE)
7697 if (! TEST_BIT (pre_insert_map[index], expr->index))
7701 /* If tmp is NULL, we found an insertion on every edge, blank the
7702 insertion vector for these edges, and insert at the start of the BB. */
7703 if (!tmp && bb != EXIT_BLOCK_PTR)
7705 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
7707 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
7708 RESET_BIT (pre_insert_map[index], expr->index);
7710 insert_insn_start_bb (insn, bb);
7714 /* We can't insert on this edge, so we'll insert at the head of the
7715 successors block. See Morgan, sec 10.5. */
7716 if ((e->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
7718 insert_insn_start_bb (insn, bb);
7722 insert_insn_on_edge (insn, e);
7726 fprintf (gcse_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
7727 e->src->index, e->dest->index);
7728 print_inline_rtx (gcse_file, insn, 6);
7729 fprintf (gcse_file, "\n");
7735 /* Remove any REG_EQUAL or REG_EQUIV notes containing a reference to the
7736 memory location in SMEXPR set in basic block BB.
7738 This could be rather expensive. */
7741 remove_reachable_equiv_notes (basic_block bb, struct ls_expr *smexpr)
7743 edge *stack = xmalloc (sizeof (edge) * n_basic_blocks), act;
7744 sbitmap visited = sbitmap_alloc (last_basic_block);
7746 rtx last, insn, note;
7747 rtx mem = smexpr->pattern;
7749 sbitmap_zero (visited);
7759 sbitmap_free (visited);
7762 act = stack[--stack_top];
7766 if (bb == EXIT_BLOCK_PTR
7767 || TEST_BIT (visited, bb->index)
7768 || TEST_BIT (ae_kill[bb->index], smexpr->index))
7770 act = act->succ_next;
7773 SET_BIT (visited, bb->index);
7775 if (TEST_BIT (st_antloc[bb->index], smexpr->index))
7777 for (last = ANTIC_STORE_LIST (smexpr);
7778 BLOCK_FOR_INSN (XEXP (last, 0)) != bb;
7779 last = XEXP (last, 1))
7781 last = XEXP (last, 0);
7784 last = NEXT_INSN (BB_END (bb));
7786 for (insn = BB_HEAD (bb); insn != last; insn = NEXT_INSN (insn))
7789 note = find_reg_equal_equiv_note (insn);
7790 if (!note || !expr_equiv_p (XEXP (note, 0), mem))
7794 fprintf (gcse_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
7796 remove_note (insn, note);
7798 act = act->succ_next;
7802 stack[stack_top++] = act;
7808 /* This routine will replace a store with a SET to a specified register. */
7811 replace_store_insn (rtx reg, rtx del, basic_block bb, struct ls_expr *smexpr)
7813 rtx insn, mem, note, set, ptr;
7815 mem = smexpr->pattern;
7816 insn = gen_move_insn (reg, SET_SRC (single_set (del)));
7817 insn = emit_insn_after (insn, del);
7822 "STORE_MOTION delete insn in BB %d:\n ", bb->index);
7823 print_inline_rtx (gcse_file, del, 6);
7824 fprintf (gcse_file, "\nSTORE MOTION replaced with insn:\n ");
7825 print_inline_rtx (gcse_file, insn, 6);
7826 fprintf (gcse_file, "\n");
7829 for (ptr = ANTIC_STORE_LIST (smexpr); ptr; ptr = XEXP (ptr, 1))
7830 if (XEXP (ptr, 0) == del)
7832 XEXP (ptr, 0) = insn;
7837 /* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
7838 they are no longer accurate provided that they are reached by this
7839 definition, so drop them. */
7840 for (; insn != NEXT_INSN (BB_END (bb)); insn = NEXT_INSN (insn))
7843 set = single_set (insn);
7846 if (expr_equiv_p (SET_DEST (set), mem))
7848 note = find_reg_equal_equiv_note (insn);
7849 if (!note || !expr_equiv_p (XEXP (note, 0), mem))
7853 fprintf (gcse_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
7855 remove_note (insn, note);
7857 remove_reachable_equiv_notes (bb, smexpr);
7861 /* Delete a store, but copy the value that would have been stored into
7862 the reaching_reg for later storing. */
7865 delete_store (struct ls_expr * expr, basic_block bb)
7869 if (expr->reaching_reg == NULL_RTX)
7870 expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
7872 reg = expr->reaching_reg;
7874 for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
7877 if (BLOCK_FOR_INSN (del) == bb)
7879 /* We know there is only one since we deleted redundant
7880 ones during the available computation. */
7881 replace_store_insn (reg, del, bb, expr);
7887 /* Free memory used by store motion. */
7890 free_store_memory (void)
7895 sbitmap_vector_free (ae_gen);
7897 sbitmap_vector_free (ae_kill);
7899 sbitmap_vector_free (transp);
7901 sbitmap_vector_free (st_antloc);
7903 sbitmap_vector_free (pre_insert_map);
7905 sbitmap_vector_free (pre_delete_map);
7906 if (reg_set_in_block)
7907 sbitmap_vector_free (reg_set_in_block);
7909 ae_gen = ae_kill = transp = st_antloc = NULL;
7910 pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
7913 /* Perform store motion. Much like gcse, except we move expressions the
7914 other way by looking at the flowgraph in reverse. */
7921 struct ls_expr * ptr;
7922 int update_flow = 0;
7926 fprintf (gcse_file, "before store motion\n");
7927 print_rtl (gcse_file, get_insns ());
7930 init_alias_analysis ();
7932 /* Find all the available and anticipatable stores. */
7933 num_stores = compute_store_table ();
7934 if (num_stores == 0)
7936 sbitmap_vector_free (reg_set_in_block);
7937 end_alias_analysis ();
7941 /* Now compute kill & transp vectors. */
7942 build_store_vectors ();
7943 add_noreturn_fake_exit_edges ();
7944 connect_infinite_loops_to_exit ();
7946 edge_list = pre_edge_rev_lcm (gcse_file, num_stores, transp, ae_gen,
7947 st_antloc, ae_kill, &pre_insert_map,
7950 /* Now we want to insert the new stores which are going to be needed. */
7951 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7954 if (TEST_BIT (pre_delete_map[bb->index], ptr->index))
7955 delete_store (ptr, bb);
7957 for (x = 0; x < NUM_EDGES (edge_list); x++)
7958 if (TEST_BIT (pre_insert_map[x], ptr->index))
7959 update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
7963 commit_edge_insertions ();
7965 free_store_memory ();
7966 free_edge_list (edge_list);
7967 remove_fake_edges ();
7968 end_alias_analysis ();
7972 /* Entry point for jump bypassing optimization pass. */
7975 bypass_jumps (FILE *file)
7979 /* We do not construct an accurate cfg in functions which call
7980 setjmp, so just punt to be safe. */
7981 if (current_function_calls_setjmp)
7984 /* For calling dump_foo fns from gdb. */
7985 debug_stderr = stderr;
7988 /* Identify the basic block information for this function, including
7989 successors and predecessors. */
7990 max_gcse_regno = max_reg_num ();
7993 dump_flow_info (file);
7995 /* Return if there's nothing to do, or it is too expensive. */
7996 if (n_basic_blocks <= 1 || is_too_expensive (_ ("jump bypassing disabled")))
7999 gcc_obstack_init (&gcse_obstack);
8002 /* We need alias. */
8003 init_alias_analysis ();
8005 /* Record where pseudo-registers are set. This data is kept accurate
8006 during each pass. ??? We could also record hard-reg information here
8007 [since it's unchanging], however it is currently done during hash table
8010 It may be tempting to compute MEM set information here too, but MEM sets
8011 will be subject to code motion one day and thus we need to compute
8012 information about memory sets when we build the hash tables. */
8014 alloc_reg_set_mem (max_gcse_regno);
8015 compute_sets (get_insns ());
8017 max_gcse_regno = max_reg_num ();
8018 alloc_gcse_mem (get_insns ());
8019 changed = one_cprop_pass (1, 1, 1);
8024 fprintf (file, "BYPASS of %s: %d basic blocks, ",
8025 (*lang_hooks.decl_printable_name) (current_function_decl, 2),
8027 fprintf (file, "%d bytes\n\n", bytes_used);
8030 obstack_free (&gcse_obstack, NULL);
8031 free_reg_set_mem ();
8033 /* We are finished with alias. */
8034 end_alias_analysis ();
8035 allocate_reg_info (max_reg_num (), FALSE, FALSE);
8040 /* Return true if the graph is too expensive to optimize. PASS is the
8041 optimization about to be performed. */
8044 is_too_expensive (const char *pass)
8046 /* Trying to perform global optimizations on flow graphs which have
8047 a high connectivity will take a long time and is unlikely to be
8048 particularly useful.
8050 In normal circumstances a cfg should have about twice as many
8051 edges as blocks. But we do not want to punish small functions
8052 which have a couple switch statements. Rather than simply
8053 threshold the number of blocks, uses something with a more
8054 graceful degradation. */
8055 if (n_edges > 20000 + n_basic_blocks * 4)
8057 if (warn_disabled_optimization)
8058 warning ("%s: %d basic blocks and %d edges/basic block",
8059 pass, n_basic_blocks, n_edges / n_basic_blocks);
8064 /* If allocating memory for the cprop bitmap would take up too much
8065 storage it's better just to disable the optimization. */
8067 * SBITMAP_SET_SIZE (max_reg_num ())
8068 * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
8070 if (warn_disabled_optimization)
8071 warning ("%s: %d basic blocks and %d registers",
8072 pass, n_basic_blocks, max_reg_num ());
8080 #include "gt-gcse.h"