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"
155 #include "hard-reg-set.h"
158 #include "insn-config.h"
160 #include "basic-block.h"
162 #include "function.h"
171 /* Propagate flow information through back edges and thus enable PRE's
172 moving loop invariant calculations out of loops.
174 Originally this tended to create worse overall code, but several
175 improvements during the development of PRE seem to have made following
176 back edges generally a win.
178 Note much of the loop invariant code motion done here would normally
179 be done by loop.c, which has more heuristics for when to move invariants
180 out of loops. At some point we might need to move some of those
181 heuristics into gcse.c. */
183 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
184 are a superset of those done by GCSE.
186 We perform the following steps:
188 1) Compute basic block information.
190 2) Compute table of places where registers are set.
192 3) Perform copy/constant propagation.
194 4) Perform global cse.
196 5) Perform another pass of copy/constant propagation.
198 Two passes of copy/constant propagation are done because the first one
199 enables more GCSE and the second one helps to clean up the copies that
200 GCSE creates. This is needed more for PRE than for Classic because Classic
201 GCSE will try to use an existing register containing the common
202 subexpression rather than create a new one. This is harder to do for PRE
203 because of the code motion (which Classic GCSE doesn't do).
205 Expressions we are interested in GCSE-ing are of the form
206 (set (pseudo-reg) (expression)).
207 Function want_to_gcse_p says what these are.
209 PRE handles moving invariant expressions out of loops (by treating them as
210 partially redundant).
212 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
213 assignment) based GVN (global value numbering). L. T. Simpson's paper
214 (Rice University) on value numbering is a useful reference for this.
216 **********************
218 We used to support multiple passes but there are diminishing returns in
219 doing so. The first pass usually makes 90% of the changes that are doable.
220 A second pass can make a few more changes made possible by the first pass.
221 Experiments show any further passes don't make enough changes to justify
224 A study of spec92 using an unlimited number of passes:
225 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
226 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
227 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
229 It was found doing copy propagation between each pass enables further
232 PRE is quite expensive in complicated functions because the DFA can take
233 awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can
234 be modified if one wants to experiment.
236 **********************
238 The steps for PRE are:
240 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
242 2) Perform the data flow analysis for PRE.
244 3) Delete the redundant instructions
246 4) Insert the required copies [if any] that make the partially
247 redundant instructions fully redundant.
249 5) For other reaching expressions, insert an instruction to copy the value
250 to a newly created pseudo that will reach the redundant instruction.
252 The deletion is done first so that when we do insertions we
253 know which pseudo reg to use.
255 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
256 argue it is not. The number of iterations for the algorithm to converge
257 is typically 2-4 so I don't view it as that expensive (relatively speaking).
259 PRE GCSE depends heavily on the second CSE pass to clean up the copies
260 we create. To make an expression reach the place where it's redundant,
261 the result of the expression is copied to a new register, and the redundant
262 expression is deleted by replacing it with this new register. Classic GCSE
263 doesn't have this problem as much as it computes the reaching defs of
264 each register in each block and thus can try to use an existing register.
266 **********************
268 A fair bit of simplicity is created by creating small functions for simple
269 tasks, even when the function is only called in one place. This may
270 measurably slow things down [or may not] by creating more function call
271 overhead than is necessary. The source is laid out so that it's trivial
272 to make the affected functions inline so that one can measure what speed
273 up, if any, can be achieved, and maybe later when things settle things can
276 Help stamp out big monolithic functions! */
278 /* GCSE global vars. */
281 static FILE *gcse_file;
283 /* Note whether or not we should run jump optimization after gcse. We
284 want to do this for two cases.
286 * If we changed any jumps via cprop.
288 * If we added any labels via edge splitting. */
290 static int run_jump_opt_after_gcse;
292 /* Bitmaps are normally not included in debugging dumps.
293 However it's useful to be able to print them from GDB.
294 We could create special functions for this, but it's simpler to
295 just allow passing stderr to the dump_foo fns. Since stderr can
296 be a macro, we store a copy here. */
297 static FILE *debug_stderr;
299 /* An obstack for our working variables. */
300 static struct obstack gcse_obstack;
302 struct reg_use {rtx reg_rtx; };
304 /* Hash table of expressions. */
308 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
310 /* Index in the available expression bitmaps. */
312 /* Next entry with the same hash. */
313 struct expr *next_same_hash;
314 /* List of anticipatable occurrences in basic blocks in the function.
315 An "anticipatable occurrence" is one that is the first occurrence in the
316 basic block, the operands are not modified in the basic block prior
317 to the occurrence and the output is not used between the start of
318 the block and the occurrence. */
319 struct occr *antic_occr;
320 /* List of available occurrence in basic blocks in the function.
321 An "available occurrence" is one that is the last occurrence in the
322 basic block and the operands are not modified by following statements in
323 the basic block [including this insn]. */
324 struct occr *avail_occr;
325 /* Non-null if the computation is PRE redundant.
326 The value is the newly created pseudo-reg to record a copy of the
327 expression in all the places that reach the redundant copy. */
331 /* Occurrence of an expression.
332 There is one per basic block. If a pattern appears more than once the
333 last appearance is used [or first for anticipatable expressions]. */
337 /* Next occurrence of this expression. */
339 /* The insn that computes the expression. */
341 /* Nonzero if this [anticipatable] occurrence has been deleted. */
343 /* Nonzero if this [available] occurrence has been copied to
345 /* ??? This is mutually exclusive with deleted_p, so they could share
350 /* Expression and copy propagation hash tables.
351 Each hash table is an array of buckets.
352 ??? It is known that if it were an array of entries, structure elements
353 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
354 not clear whether in the final analysis a sufficient amount of memory would
355 be saved as the size of the available expression bitmaps would be larger
356 [one could build a mapping table without holes afterwards though].
357 Someday I'll perform the computation and figure it out. */
362 This is an array of `expr_hash_table_size' elements. */
365 /* Size of the hash table, in elements. */
368 /* Number of hash table elements. */
369 unsigned int n_elems;
371 /* Whether the table is expression of copy propagation one. */
375 /* Expression hash table. */
376 static struct hash_table expr_hash_table;
378 /* Copy propagation hash table. */
379 static struct hash_table set_hash_table;
381 /* Mapping of uids to cuids.
382 Only real insns get cuids. */
383 static int *uid_cuid;
385 /* Highest UID in UID_CUID. */
388 /* Get the cuid of an insn. */
389 #ifdef ENABLE_CHECKING
390 #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
392 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
395 /* Number of cuids. */
398 /* Mapping of cuids to insns. */
399 static rtx *cuid_insn;
401 /* Get insn from cuid. */
402 #define CUID_INSN(CUID) (cuid_insn[CUID])
404 /* Maximum register number in function prior to doing gcse + 1.
405 Registers created during this pass have regno >= max_gcse_regno.
406 This is named with "gcse" to not collide with global of same name. */
407 static unsigned int max_gcse_regno;
409 /* Table of registers that are modified.
411 For each register, each element is a list of places where the pseudo-reg
414 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
415 requires knowledge of which blocks kill which regs [and thus could use
416 a bitmap instead of the lists `reg_set_table' uses].
418 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
419 num-regs) [however perhaps it may be useful to keep the data as is]. One
420 advantage of recording things this way is that `reg_set_table' is fairly
421 sparse with respect to pseudo regs but for hard regs could be fairly dense
422 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
423 up functions like compute_transp since in the case of pseudo-regs we only
424 need to iterate over the number of times a pseudo-reg is set, not over the
425 number of basic blocks [clearly there is a bit of a slow down in the cases
426 where a pseudo is set more than once in a block, however it is believed
427 that the net effect is to speed things up]. This isn't done for hard-regs
428 because recording call-clobbered hard-regs in `reg_set_table' at each
429 function call can consume a fair bit of memory, and iterating over
430 hard-regs stored this way in compute_transp will be more expensive. */
432 typedef struct reg_set
434 /* The next setting of this register. */
435 struct reg_set *next;
436 /* The insn where it was set. */
440 static reg_set **reg_set_table;
442 /* Size of `reg_set_table'.
443 The table starts out at max_gcse_regno + slop, and is enlarged as
445 static int reg_set_table_size;
447 /* Amount to grow `reg_set_table' by when it's full. */
448 #define REG_SET_TABLE_SLOP 100
450 /* This is a list of expressions which are MEMs and will be used by load
452 Load motion tracks MEMs which aren't killed by
453 anything except itself. (ie, loads and stores to a single location).
454 We can then allow movement of these MEM refs with a little special
455 allowance. (all stores copy the same value to the reaching reg used
456 for the loads). This means all values used to store into memory must have
457 no side effects so we can re-issue the setter value.
458 Store Motion uses this structure as an expression table to track stores
459 which look interesting, and might be moveable towards the exit block. */
463 struct expr * expr; /* Gcse expression reference for LM. */
464 rtx pattern; /* Pattern of this mem. */
465 rtx pattern_regs; /* List of registers mentioned by the mem. */
466 rtx loads; /* INSN list of loads seen. */
467 rtx stores; /* INSN list of stores seen. */
468 struct ls_expr * next; /* Next in the list. */
469 int invalid; /* Invalid for some reason. */
470 int index; /* If it maps to a bitmap index. */
471 int hash_index; /* Index when in a hash table. */
472 rtx reaching_reg; /* Register to use when re-writing. */
475 /* Array of implicit set patterns indexed by basic block index. */
476 static rtx *implicit_sets;
478 /* Head of the list of load/store memory refs. */
479 static struct ls_expr * pre_ldst_mems = NULL;
481 /* Bitmap containing one bit for each register in the program.
482 Used when performing GCSE to track which registers have been set since
483 the start of the basic block. */
484 static regset reg_set_bitmap;
486 /* For each block, a bitmap of registers set in the block.
487 This is used by expr_killed_p and compute_transp.
488 It is computed during hash table computation and not by compute_sets
489 as it includes registers added since the last pass (or between cprop and
490 gcse) and it's currently not easy to realloc sbitmap vectors. */
491 static sbitmap *reg_set_in_block;
493 /* Array, indexed by basic block number for a list of insns which modify
494 memory within that block. */
495 static rtx * modify_mem_list;
496 bitmap modify_mem_list_set;
498 /* This array parallels modify_mem_list, but is kept canonicalized. */
499 static rtx * canon_modify_mem_list;
500 bitmap canon_modify_mem_list_set;
501 /* Various variables for statistics gathering. */
503 /* Memory used in a pass.
504 This isn't intended to be absolutely precise. Its intent is only
505 to keep an eye on memory usage. */
506 static int bytes_used;
508 /* GCSE substitutions made. */
509 static int gcse_subst_count;
510 /* Number of copy instructions created. */
511 static int gcse_create_count;
512 /* Number of constants propagated. */
513 static int const_prop_count;
514 /* Number of copys propagated. */
515 static int copy_prop_count;
517 /* These variables are used by classic GCSE.
518 Normally they'd be defined a bit later, but `rd_gen' needs to
519 be declared sooner. */
521 /* Each block has a bitmap of each type.
522 The length of each blocks bitmap is:
524 max_cuid - for reaching definitions
525 n_exprs - for available expressions
527 Thus we view the bitmaps as 2 dimensional arrays. i.e.
528 rd_kill[block_num][cuid_num]
529 ae_kill[block_num][expr_num] */
531 /* For reaching defs */
532 static sbitmap *rd_kill, *rd_gen, *reaching_defs, *rd_out;
534 /* for available exprs */
535 static sbitmap *ae_kill, *ae_gen, *ae_in, *ae_out;
537 /* Objects of this type are passed around by the null-pointer check
539 struct null_pointer_info
541 /* The basic block being processed. */
542 basic_block current_block;
543 /* The first register to be handled in this pass. */
544 unsigned int min_reg;
545 /* One greater than the last register to be handled in this pass. */
546 unsigned int max_reg;
547 sbitmap *nonnull_local;
548 sbitmap *nonnull_killed;
551 static void compute_can_copy (void);
552 static void *gmalloc (size_t) ATTRIBUTE_MALLOC;
553 static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC;
554 static void *grealloc (void *, size_t);
555 static void *gcse_alloc (unsigned long);
556 static void alloc_gcse_mem (rtx);
557 static void free_gcse_mem (void);
558 static void alloc_reg_set_mem (int);
559 static void free_reg_set_mem (void);
560 static int get_bitmap_width (int, int, int);
561 static void record_one_set (int, rtx);
562 static void replace_one_set (int, rtx, rtx);
563 static void record_set_info (rtx, rtx, void *);
564 static void compute_sets (rtx);
565 static void hash_scan_insn (rtx, struct hash_table *, int);
566 static void hash_scan_set (rtx, rtx, struct hash_table *);
567 static void hash_scan_clobber (rtx, rtx, struct hash_table *);
568 static void hash_scan_call (rtx, rtx, struct hash_table *);
569 static int want_to_gcse_p (rtx);
570 static bool gcse_constant_p (rtx);
571 static int oprs_unchanged_p (rtx, rtx, int);
572 static int oprs_anticipatable_p (rtx, rtx);
573 static int oprs_available_p (rtx, rtx);
574 static void insert_expr_in_table (rtx, enum machine_mode, rtx, int, int,
575 struct hash_table *);
576 static void insert_set_in_table (rtx, rtx, struct hash_table *);
577 static unsigned int hash_expr (rtx, enum machine_mode, int *, int);
578 static unsigned int hash_expr_1 (rtx, enum machine_mode, int *);
579 static unsigned int hash_string_1 (const char *);
580 static unsigned int hash_set (int, int);
581 static int expr_equiv_p (rtx, rtx);
582 static void record_last_reg_set_info (rtx, int);
583 static void record_last_mem_set_info (rtx);
584 static void record_last_set_info (rtx, rtx, void *);
585 static void compute_hash_table (struct hash_table *);
586 static void alloc_hash_table (int, struct hash_table *, int);
587 static void free_hash_table (struct hash_table *);
588 static void compute_hash_table_work (struct hash_table *);
589 static void dump_hash_table (FILE *, const char *, struct hash_table *);
590 static struct expr *lookup_expr (rtx, struct hash_table *);
591 static struct expr *lookup_set (unsigned int, struct hash_table *);
592 static struct expr *next_set (unsigned int, struct expr *);
593 static void reset_opr_set_tables (void);
594 static int oprs_not_set_p (rtx, rtx);
595 static void mark_call (rtx);
596 static void mark_set (rtx, rtx);
597 static void mark_clobber (rtx, rtx);
598 static void mark_oprs_set (rtx);
599 static void alloc_cprop_mem (int, int);
600 static void free_cprop_mem (void);
601 static void compute_transp (rtx, int, sbitmap *, int);
602 static void compute_transpout (void);
603 static void compute_local_properties (sbitmap *, sbitmap *, sbitmap *,
604 struct hash_table *);
605 static void compute_cprop_data (void);
606 static void find_used_regs (rtx *, void *);
607 static int try_replace_reg (rtx, rtx, rtx);
608 static struct expr *find_avail_set (int, rtx);
609 static int cprop_jump (basic_block, rtx, rtx, rtx, rtx);
610 static void mems_conflict_for_gcse_p (rtx, rtx, void *);
611 static int load_killed_in_block_p (basic_block, int, rtx, int);
612 static void canon_list_insert (rtx, rtx, void *);
613 static int cprop_insn (rtx, int);
614 static int cprop (int);
615 static void find_implicit_sets (void);
616 static int one_cprop_pass (int, int, int);
617 static bool constprop_register (rtx, rtx, rtx, int);
618 static struct expr *find_bypass_set (int, int);
619 static bool reg_killed_on_edge (rtx, edge);
620 static int bypass_block (basic_block, rtx, rtx);
621 static int bypass_conditional_jumps (void);
622 static void alloc_pre_mem (int, int);
623 static void free_pre_mem (void);
624 static void compute_pre_data (void);
625 static int pre_expr_reaches_here_p (basic_block, struct expr *,
627 static void insert_insn_end_bb (struct expr *, basic_block, int);
628 static void pre_insert_copy_insn (struct expr *, rtx);
629 static void pre_insert_copies (void);
630 static int pre_delete (void);
631 static int pre_gcse (void);
632 static int one_pre_gcse_pass (int);
633 static void add_label_notes (rtx, rtx);
634 static void alloc_code_hoist_mem (int, int);
635 static void free_code_hoist_mem (void);
636 static void compute_code_hoist_vbeinout (void);
637 static void compute_code_hoist_data (void);
638 static int hoist_expr_reaches_here_p (basic_block, int, basic_block, char *);
639 static void hoist_code (void);
640 static int one_code_hoisting_pass (void);
641 static void alloc_rd_mem (int, int);
642 static void free_rd_mem (void);
643 static void handle_rd_kill_set (rtx, int, basic_block);
644 static void compute_kill_rd (void);
645 static void compute_rd (void);
646 static void alloc_avail_expr_mem (int, int);
647 static void free_avail_expr_mem (void);
648 static void compute_ae_gen (struct hash_table *);
649 static int expr_killed_p (rtx, basic_block);
650 static void compute_ae_kill (sbitmap *, sbitmap *, struct hash_table *);
651 static int expr_reaches_here_p (struct occr *, struct expr *, basic_block,
653 static rtx computing_insn (struct expr *, rtx);
654 static int def_reaches_here_p (rtx, rtx);
655 static int can_disregard_other_sets (struct reg_set **, rtx, int);
656 static int handle_avail_expr (rtx, struct expr *);
657 static int classic_gcse (void);
658 static int one_classic_gcse_pass (int);
659 static void invalidate_nonnull_info (rtx, rtx, void *);
660 static int delete_null_pointer_checks_1 (unsigned int *, sbitmap *, sbitmap *,
661 struct null_pointer_info *);
662 static rtx process_insert_insn (struct expr *);
663 static int pre_edge_insert (struct edge_list *, struct expr **);
664 static int expr_reaches_here_p_work (struct occr *, struct expr *,
665 basic_block, int, char *);
666 static int pre_expr_reaches_here_p_work (basic_block, struct expr *,
667 basic_block, char *);
668 static struct ls_expr * ldst_entry (rtx);
669 static void free_ldst_entry (struct ls_expr *);
670 static void free_ldst_mems (void);
671 static void print_ldst_list (FILE *);
672 static struct ls_expr * find_rtx_in_ldst (rtx);
673 static int enumerate_ldsts (void);
674 static inline struct ls_expr * first_ls_expr (void);
675 static inline struct ls_expr * next_ls_expr (struct ls_expr *);
676 static int simple_mem (rtx);
677 static void invalidate_any_buried_refs (rtx);
678 static void compute_ld_motion_mems (void);
679 static void trim_ld_motion_mems (void);
680 static void update_ld_motion_stores (struct expr *);
681 static void reg_set_info (rtx, rtx, void *);
682 static bool store_ops_ok (rtx, int *);
683 static rtx extract_mentioned_regs (rtx);
684 static rtx extract_mentioned_regs_helper (rtx, rtx);
685 static void find_moveable_store (rtx, int *, int *);
686 static int compute_store_table (void);
687 static bool load_kills_store (rtx, rtx, int);
688 static bool find_loads (rtx, rtx, int);
689 static bool store_killed_in_insn (rtx, rtx, rtx, int);
690 static bool store_killed_after (rtx, rtx, rtx, basic_block, int *, rtx *);
691 static bool store_killed_before (rtx, rtx, rtx, basic_block, int *);
692 static void build_store_vectors (void);
693 static void insert_insn_start_bb (rtx, basic_block);
694 static int insert_store (struct ls_expr *, edge);
695 static void replace_store_insn (rtx, rtx, basic_block);
696 static void delete_store (struct ls_expr *, basic_block);
697 static void free_store_memory (void);
698 static void store_motion (void);
699 static void free_insn_expr_list_list (rtx *);
700 static void clear_modify_mem_tables (void);
701 static void free_modify_mem_tables (void);
702 static rtx gcse_emit_move_after (rtx, rtx, rtx);
703 static void local_cprop_find_used_regs (rtx *, void *);
704 static bool do_local_cprop (rtx, rtx, int, rtx*);
705 static bool adjust_libcall_notes (rtx, rtx, rtx, rtx*);
706 static void local_cprop_pass (int);
707 static bool is_too_expensive (const char *);
710 /* Entry point for global common subexpression elimination.
711 F is the first instruction in the function. */
714 gcse_main (rtx f, FILE *file)
717 /* Bytes used at start of pass. */
718 int initial_bytes_used;
719 /* Maximum number of bytes used by a pass. */
721 /* Point to release obstack data from for each pass. */
722 char *gcse_obstack_bottom;
724 /* We do not construct an accurate cfg in functions which call
725 setjmp, so just punt to be safe. */
726 if (current_function_calls_setjmp)
729 /* Assume that we do not need to run jump optimizations after gcse. */
730 run_jump_opt_after_gcse = 0;
732 /* For calling dump_foo fns from gdb. */
733 debug_stderr = stderr;
736 /* Identify the basic block information for this function, including
737 successors and predecessors. */
738 max_gcse_regno = max_reg_num ();
741 dump_flow_info (file);
743 /* Return if there's nothing to do, or it is too expensive. */
744 if (n_basic_blocks <= 1 || is_too_expensive (_("GCSE disabled")))
747 gcc_obstack_init (&gcse_obstack);
751 init_alias_analysis ();
752 /* Record where pseudo-registers are set. This data is kept accurate
753 during each pass. ??? We could also record hard-reg information here
754 [since it's unchanging], however it is currently done during hash table
757 It may be tempting to compute MEM set information here too, but MEM sets
758 will be subject to code motion one day and thus we need to compute
759 information about memory sets when we build the hash tables. */
761 alloc_reg_set_mem (max_gcse_regno);
765 initial_bytes_used = bytes_used;
767 gcse_obstack_bottom = gcse_alloc (1);
769 while (changed && pass < MAX_GCSE_PASSES)
773 fprintf (file, "GCSE pass %d\n\n", pass + 1);
775 /* Initialize bytes_used to the space for the pred/succ lists,
776 and the reg_set_table data. */
777 bytes_used = initial_bytes_used;
779 /* Each pass may create new registers, so recalculate each time. */
780 max_gcse_regno = max_reg_num ();
784 /* Don't allow constant propagation to modify jumps
786 changed = one_cprop_pass (pass + 1, 0, 0);
789 changed |= one_classic_gcse_pass (pass + 1);
792 changed |= one_pre_gcse_pass (pass + 1);
793 /* We may have just created new basic blocks. Release and
794 recompute various things which are sized on the number of
798 free_modify_mem_tables ();
799 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
800 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
803 alloc_reg_set_mem (max_reg_num ());
805 run_jump_opt_after_gcse = 1;
808 if (max_pass_bytes < bytes_used)
809 max_pass_bytes = bytes_used;
811 /* Free up memory, then reallocate for code hoisting. We can
812 not re-use the existing allocated memory because the tables
813 will not have info for the insns or registers created by
814 partial redundancy elimination. */
817 /* It does not make sense to run code hoisting unless we optimizing
818 for code size -- it rarely makes programs faster, and can make
819 them bigger if we did partial redundancy elimination (when optimizing
820 for space, we use a classic gcse algorithm instead of partial
821 redundancy algorithms). */
824 max_gcse_regno = max_reg_num ();
826 changed |= one_code_hoisting_pass ();
829 if (max_pass_bytes < bytes_used)
830 max_pass_bytes = bytes_used;
835 fprintf (file, "\n");
839 obstack_free (&gcse_obstack, gcse_obstack_bottom);
843 /* Do one last pass of copy propagation, including cprop into
844 conditional jumps. */
846 max_gcse_regno = max_reg_num ();
848 /* This time, go ahead and allow cprop to alter jumps. */
849 one_cprop_pass (pass + 1, 1, 0);
854 fprintf (file, "GCSE of %s: %d basic blocks, ",
855 current_function_name, n_basic_blocks);
856 fprintf (file, "%d pass%s, %d bytes\n\n",
857 pass, pass > 1 ? "es" : "", max_pass_bytes);
860 obstack_free (&gcse_obstack, NULL);
862 /* We are finished with alias. */
863 end_alias_analysis ();
864 allocate_reg_info (max_reg_num (), FALSE, FALSE);
866 if (!optimize_size && flag_gcse_sm)
869 /* Record where pseudo-registers are set. */
870 return run_jump_opt_after_gcse;
873 /* Misc. utilities. */
875 /* Nonzero for each mode that supports (set (reg) (reg)).
876 This is trivially true for integer and floating point values.
877 It may or may not be true for condition codes. */
878 static char can_copy[(int) NUM_MACHINE_MODES];
880 /* Compute which modes support reg/reg copy operations. */
883 compute_can_copy (void)
886 #ifndef AVOID_CCMODE_COPIES
889 memset (can_copy, 0, NUM_MACHINE_MODES);
892 for (i = 0; i < NUM_MACHINE_MODES; i++)
893 if (GET_MODE_CLASS (i) == MODE_CC)
895 #ifdef AVOID_CCMODE_COPIES
898 reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1);
899 insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
900 if (recog (PATTERN (insn), insn, NULL) >= 0)
910 /* Returns whether the mode supports reg/reg copy operations. */
913 can_copy_p (enum machine_mode mode)
915 static bool can_copy_init_p = false;
917 if (! can_copy_init_p)
920 can_copy_init_p = true;
923 return can_copy[mode] != 0;
926 /* Cover function to xmalloc to record bytes allocated. */
929 gmalloc (size_t size)
932 return xmalloc (size);
935 /* Cover function to xcalloc to record bytes allocated. */
938 gcalloc (size_t nelem, size_t elsize)
940 bytes_used += nelem * elsize;
941 return xcalloc (nelem, elsize);
944 /* Cover function to xrealloc.
945 We don't record the additional size since we don't know it.
946 It won't affect memory usage stats much anyway. */
949 grealloc (void *ptr, size_t size)
951 return xrealloc (ptr, size);
954 /* Cover function to obstack_alloc. */
957 gcse_alloc (unsigned long size)
960 return obstack_alloc (&gcse_obstack, size);
963 /* Allocate memory for the cuid mapping array,
964 and reg/memory set tracking tables.
966 This is called at the start of each pass. */
969 alloc_gcse_mem (rtx f)
974 /* Find the largest UID and create a mapping from UIDs to CUIDs.
975 CUIDs are like UIDs except they increase monotonically, have no gaps,
976 and only apply to real insns. */
978 max_uid = get_max_uid ();
979 uid_cuid = gcalloc (max_uid + 1, sizeof (int));
980 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
983 uid_cuid[INSN_UID (insn)] = i++;
985 uid_cuid[INSN_UID (insn)] = i;
988 /* Create a table mapping cuids to insns. */
991 cuid_insn = gcalloc (max_cuid + 1, sizeof (rtx));
992 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
994 CUID_INSN (i++) = insn;
996 /* Allocate vars to track sets of regs. */
997 reg_set_bitmap = BITMAP_XMALLOC ();
999 /* Allocate vars to track sets of regs, memory per block. */
1000 reg_set_in_block = sbitmap_vector_alloc (last_basic_block, max_gcse_regno);
1001 /* Allocate array to keep a list of insns which modify memory in each
1003 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
1004 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
1005 modify_mem_list_set = BITMAP_XMALLOC ();
1006 canon_modify_mem_list_set = BITMAP_XMALLOC ();
1009 /* Free memory allocated by alloc_gcse_mem. */
1012 free_gcse_mem (void)
1017 BITMAP_XFREE (reg_set_bitmap);
1019 sbitmap_vector_free (reg_set_in_block);
1020 free_modify_mem_tables ();
1021 BITMAP_XFREE (modify_mem_list_set);
1022 BITMAP_XFREE (canon_modify_mem_list_set);
1025 /* Many of the global optimization algorithms work by solving dataflow
1026 equations for various expressions. Initially, some local value is
1027 computed for each expression in each block. Then, the values across the
1028 various blocks are combined (by following flow graph edges) to arrive at
1029 global values. Conceptually, each set of equations is independent. We
1030 may therefore solve all the equations in parallel, solve them one at a
1031 time, or pick any intermediate approach.
1033 When you're going to need N two-dimensional bitmaps, each X (say, the
1034 number of blocks) by Y (say, the number of expressions), call this
1035 function. It's not important what X and Y represent; only that Y
1036 correspond to the things that can be done in parallel. This function will
1037 return an appropriate chunking factor C; you should solve C sets of
1038 equations in parallel. By going through this function, we can easily
1039 trade space against time; by solving fewer equations in parallel we use
1043 get_bitmap_width (int n, int x, int y)
1045 /* It's not really worth figuring out *exactly* how much memory will
1046 be used by a particular choice. The important thing is to get
1047 something approximately right. */
1048 size_t max_bitmap_memory = 10 * 1024 * 1024;
1050 /* The number of bytes we'd use for a single column of minimum
1052 size_t column_size = n * x * sizeof (SBITMAP_ELT_TYPE);
1054 /* Often, it's reasonable just to solve all the equations in
1056 if (column_size * SBITMAP_SET_SIZE (y) <= max_bitmap_memory)
1059 /* Otherwise, pick the largest width we can, without going over the
1061 return SBITMAP_ELT_BITS * ((max_bitmap_memory + column_size - 1)
1065 /* Compute the local properties of each recorded expression.
1067 Local properties are those that are defined by the block, irrespective of
1070 An expression is transparent in a block if its operands are not modified
1073 An expression is computed (locally available) in a block if it is computed
1074 at least once and expression would contain the same value if the
1075 computation was moved to the end of the block.
1077 An expression is locally anticipatable in a block if it is computed at
1078 least once and expression would contain the same value if the computation
1079 was moved to the beginning of the block.
1081 We call this routine for cprop, pre and code hoisting. They all compute
1082 basically the same information and thus can easily share this code.
1084 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1085 properties. If NULL, then it is not necessary to compute or record that
1086 particular property.
1088 TABLE controls which hash table to look at. If it is set hash table,
1089 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1093 compute_local_properties (sbitmap *transp, sbitmap *comp, sbitmap *antloc, struct hash_table *table)
1097 /* Initialize any bitmaps that were passed in. */
1101 sbitmap_vector_zero (transp, last_basic_block);
1103 sbitmap_vector_ones (transp, last_basic_block);
1107 sbitmap_vector_zero (comp, last_basic_block);
1109 sbitmap_vector_zero (antloc, last_basic_block);
1111 for (i = 0; i < table->size; i++)
1115 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
1117 int indx = expr->bitmap_index;
1120 /* The expression is transparent in this block if it is not killed.
1121 We start by assuming all are transparent [none are killed], and
1122 then reset the bits for those that are. */
1124 compute_transp (expr->expr, indx, transp, table->set_p);
1126 /* The occurrences recorded in antic_occr are exactly those that
1127 we want to set to nonzero in ANTLOC. */
1129 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
1131 SET_BIT (antloc[BLOCK_NUM (occr->insn)], indx);
1133 /* While we're scanning the table, this is a good place to
1135 occr->deleted_p = 0;
1138 /* The occurrences recorded in avail_occr are exactly those that
1139 we want to set to nonzero in COMP. */
1141 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
1143 SET_BIT (comp[BLOCK_NUM (occr->insn)], indx);
1145 /* While we're scanning the table, this is a good place to
1150 /* While we're scanning the table, this is a good place to
1152 expr->reaching_reg = 0;
1157 /* Register set information.
1159 `reg_set_table' records where each register is set or otherwise
1162 static struct obstack reg_set_obstack;
1165 alloc_reg_set_mem (int n_regs)
1167 reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
1168 reg_set_table = gcalloc (reg_set_table_size, sizeof (struct reg_set *));
1170 gcc_obstack_init (®_set_obstack);
1174 free_reg_set_mem (void)
1176 free (reg_set_table);
1177 obstack_free (®_set_obstack, NULL);
1180 /* An OLD_INSN that used to set REGNO was replaced by NEW_INSN.
1181 Update the corresponding `reg_set_table' entry accordingly.
1182 We assume that NEW_INSN is not already recorded in reg_set_table[regno]. */
1185 replace_one_set (int regno, rtx old_insn, rtx new_insn)
1187 struct reg_set *reg_info;
1188 if (regno >= reg_set_table_size)
1190 for (reg_info = reg_set_table[regno]; reg_info; reg_info = reg_info->next)
1191 if (reg_info->insn == old_insn)
1193 reg_info->insn = new_insn;
1198 /* Record REGNO in the reg_set table. */
1201 record_one_set (int regno, rtx insn)
1203 /* Allocate a new reg_set element and link it onto the list. */
1204 struct reg_set *new_reg_info;
1206 /* If the table isn't big enough, enlarge it. */
1207 if (regno >= reg_set_table_size)
1209 int new_size = regno + REG_SET_TABLE_SLOP;
1211 reg_set_table = grealloc (reg_set_table,
1212 new_size * sizeof (struct reg_set *));
1213 memset (reg_set_table + reg_set_table_size, 0,
1214 (new_size - reg_set_table_size) * sizeof (struct reg_set *));
1215 reg_set_table_size = new_size;
1218 new_reg_info = obstack_alloc (®_set_obstack, sizeof (struct reg_set));
1219 bytes_used += sizeof (struct reg_set);
1220 new_reg_info->insn = insn;
1221 new_reg_info->next = reg_set_table[regno];
1222 reg_set_table[regno] = new_reg_info;
1225 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1226 an insn. The DATA is really the instruction in which the SET is
1230 record_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
1232 rtx record_set_insn = (rtx) data;
1234 if (GET_CODE (dest) == REG && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
1235 record_one_set (REGNO (dest), record_set_insn);
1238 /* Scan the function and record each set of each pseudo-register.
1240 This is called once, at the start of the gcse pass. See the comments for
1241 `reg_set_table' for further documentation. */
1244 compute_sets (rtx f)
1248 for (insn = f; insn != 0; insn = NEXT_INSN (insn))
1250 note_stores (PATTERN (insn), record_set_info, insn);
1253 /* Hash table support. */
1255 struct reg_avail_info
1257 basic_block last_bb;
1262 static struct reg_avail_info *reg_avail_info;
1263 static basic_block current_bb;
1266 /* See whether X, the source of a set, is something we want to consider for
1269 static GTY(()) rtx test_insn;
1271 want_to_gcse_p (rtx x)
1273 int num_clobbers = 0;
1276 switch (GET_CODE (x))
1284 case CONSTANT_P_RTX:
1291 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1292 if (general_operand (x, GET_MODE (x)))
1294 else if (GET_MODE (x) == VOIDmode)
1297 /* Otherwise, check if we can make a valid insn from it. First initialize
1298 our test insn if we haven't already. */
1302 = make_insn_raw (gen_rtx_SET (VOIDmode,
1303 gen_rtx_REG (word_mode,
1304 FIRST_PSEUDO_REGISTER * 2),
1306 NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0;
1309 /* Now make an insn like the one we would make when GCSE'ing and see if
1311 PUT_MODE (SET_DEST (PATTERN (test_insn)), GET_MODE (x));
1312 SET_SRC (PATTERN (test_insn)) = x;
1313 return ((icode = recog (PATTERN (test_insn), test_insn, &num_clobbers)) >= 0
1314 && (num_clobbers == 0 || ! added_clobbers_hard_reg_p (icode)));
1317 /* Return nonzero if the operands of expression X are unchanged from the
1318 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1319 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1322 oprs_unchanged_p (rtx x, rtx insn, int avail_p)
1331 code = GET_CODE (x);
1336 struct reg_avail_info *info = ®_avail_info[REGNO (x)];
1338 if (info->last_bb != current_bb)
1341 return info->last_set < INSN_CUID (insn);
1343 return info->first_set >= INSN_CUID (insn);
1347 if (load_killed_in_block_p (current_bb, INSN_CUID (insn),
1351 return oprs_unchanged_p (XEXP (x, 0), insn, avail_p);
1377 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1381 /* If we are about to do the last recursive call needed at this
1382 level, change it into iteration. This function is called enough
1385 return oprs_unchanged_p (XEXP (x, i), insn, avail_p);
1387 else if (! oprs_unchanged_p (XEXP (x, i), insn, avail_p))
1390 else if (fmt[i] == 'E')
1391 for (j = 0; j < XVECLEN (x, i); j++)
1392 if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p))
1399 /* Used for communication between mems_conflict_for_gcse_p and
1400 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1401 conflict between two memory references. */
1402 static int gcse_mems_conflict_p;
1404 /* Used for communication between mems_conflict_for_gcse_p and
1405 load_killed_in_block_p. A memory reference for a load instruction,
1406 mems_conflict_for_gcse_p will see if a memory store conflicts with
1407 this memory load. */
1408 static rtx gcse_mem_operand;
1410 /* DEST is the output of an instruction. If it is a memory reference, and
1411 possibly conflicts with the load found in gcse_mem_operand, then set
1412 gcse_mems_conflict_p to a nonzero value. */
1415 mems_conflict_for_gcse_p (rtx dest, rtx setter ATTRIBUTE_UNUSED,
1416 void *data ATTRIBUTE_UNUSED)
1418 while (GET_CODE (dest) == SUBREG
1419 || GET_CODE (dest) == ZERO_EXTRACT
1420 || GET_CODE (dest) == SIGN_EXTRACT
1421 || GET_CODE (dest) == STRICT_LOW_PART)
1422 dest = XEXP (dest, 0);
1424 /* If DEST is not a MEM, then it will not conflict with the load. Note
1425 that function calls are assumed to clobber memory, but are handled
1427 if (GET_CODE (dest) != MEM)
1430 /* If we are setting a MEM in our list of specially recognized MEMs,
1431 don't mark as killed this time. */
1433 if (expr_equiv_p (dest, gcse_mem_operand) && pre_ldst_mems != NULL)
1435 if (!find_rtx_in_ldst (dest))
1436 gcse_mems_conflict_p = 1;
1440 if (true_dependence (dest, GET_MODE (dest), gcse_mem_operand,
1442 gcse_mems_conflict_p = 1;
1445 /* Return nonzero if the expression in X (a memory reference) is killed
1446 in block BB before or after the insn with the CUID in UID_LIMIT.
1447 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1450 To check the entire block, set UID_LIMIT to max_uid + 1 and
1454 load_killed_in_block_p (basic_block bb, int uid_limit, rtx x, int avail_p)
1456 rtx list_entry = modify_mem_list[bb->index];
1460 /* Ignore entries in the list that do not apply. */
1462 && INSN_CUID (XEXP (list_entry, 0)) < uid_limit)
1464 && INSN_CUID (XEXP (list_entry, 0)) > uid_limit))
1466 list_entry = XEXP (list_entry, 1);
1470 setter = XEXP (list_entry, 0);
1472 /* If SETTER is a call everything is clobbered. Note that calls
1473 to pure functions are never put on the list, so we need not
1474 worry about them. */
1475 if (GET_CODE (setter) == CALL_INSN)
1478 /* SETTER must be an INSN of some kind that sets memory. Call
1479 note_stores to examine each hunk of memory that is modified.
1481 The note_stores interface is pretty limited, so we have to
1482 communicate via global variables. Yuk. */
1483 gcse_mem_operand = x;
1484 gcse_mems_conflict_p = 0;
1485 note_stores (PATTERN (setter), mems_conflict_for_gcse_p, NULL);
1486 if (gcse_mems_conflict_p)
1488 list_entry = XEXP (list_entry, 1);
1493 /* Return nonzero if the operands of expression X are unchanged from
1494 the start of INSN's basic block up to but not including INSN. */
1497 oprs_anticipatable_p (rtx x, rtx insn)
1499 return oprs_unchanged_p (x, insn, 0);
1502 /* Return nonzero if the operands of expression X are unchanged from
1503 INSN to the end of INSN's basic block. */
1506 oprs_available_p (rtx x, rtx insn)
1508 return oprs_unchanged_p (x, insn, 1);
1511 /* Hash expression X.
1513 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1514 indicating if a volatile operand is found or if the expression contains
1515 something we don't want to insert in the table.
1517 ??? One might want to merge this with canon_hash. Later. */
1520 hash_expr (rtx x, enum machine_mode mode, int *do_not_record_p, int hash_table_size)
1524 *do_not_record_p = 0;
1526 hash = hash_expr_1 (x, mode, do_not_record_p);
1527 return hash % hash_table_size;
1530 /* Hash a string. Just add its bytes up. */
1532 static inline unsigned
1533 hash_string_1 (const char *ps)
1536 const unsigned char *p = (const unsigned char *) ps;
1545 /* Subroutine of hash_expr to do the actual work. */
1548 hash_expr_1 (rtx x, enum machine_mode mode, int *do_not_record_p)
1555 /* Used to turn recursion into iteration. We can't rely on GCC's
1556 tail-recursion elimination since we need to keep accumulating values
1563 code = GET_CODE (x);
1567 hash += ((unsigned int) REG << 7) + REGNO (x);
1571 hash += (((unsigned int) CONST_INT << 7) + (unsigned int) mode
1572 + (unsigned int) INTVAL (x));
1576 /* This is like the general case, except that it only counts
1577 the integers representing the constant. */
1578 hash += (unsigned int) code + (unsigned int) GET_MODE (x);
1579 if (GET_MODE (x) != VOIDmode)
1580 for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++)
1581 hash += (unsigned int) XWINT (x, i);
1583 hash += ((unsigned int) CONST_DOUBLE_LOW (x)
1584 + (unsigned int) CONST_DOUBLE_HIGH (x));
1592 units = CONST_VECTOR_NUNITS (x);
1594 for (i = 0; i < units; ++i)
1596 elt = CONST_VECTOR_ELT (x, i);
1597 hash += hash_expr_1 (elt, GET_MODE (elt), do_not_record_p);
1603 /* Assume there is only one rtx object for any given label. */
1605 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1606 differences and differences between each stage's debugging dumps. */
1607 hash += (((unsigned int) LABEL_REF << 7)
1608 + CODE_LABEL_NUMBER (XEXP (x, 0)));
1613 /* Don't hash on the symbol's address to avoid bootstrap differences.
1614 Different hash values may cause expressions to be recorded in
1615 different orders and thus different registers to be used in the
1616 final assembler. This also avoids differences in the dump files
1617 between various stages. */
1619 const unsigned char *p = (const unsigned char *) XSTR (x, 0);
1622 h += (h << 7) + *p++; /* ??? revisit */
1624 hash += ((unsigned int) SYMBOL_REF << 7) + h;
1629 if (MEM_VOLATILE_P (x))
1631 *do_not_record_p = 1;
1635 hash += (unsigned int) MEM;
1636 /* We used alias set for hashing, but this is not good, since the alias
1637 set may differ in -fprofile-arcs and -fbranch-probabilities compilation
1638 causing the profiles to fail to match. */
1649 case UNSPEC_VOLATILE:
1650 *do_not_record_p = 1;
1654 if (MEM_VOLATILE_P (x))
1656 *do_not_record_p = 1;
1661 /* We don't want to take the filename and line into account. */
1662 hash += (unsigned) code + (unsigned) GET_MODE (x)
1663 + hash_string_1 (ASM_OPERANDS_TEMPLATE (x))
1664 + hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x))
1665 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x);
1667 if (ASM_OPERANDS_INPUT_LENGTH (x))
1669 for (i = 1; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
1671 hash += (hash_expr_1 (ASM_OPERANDS_INPUT (x, i),
1672 GET_MODE (ASM_OPERANDS_INPUT (x, i)),
1674 + hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT
1678 hash += hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x, 0));
1679 x = ASM_OPERANDS_INPUT (x, 0);
1680 mode = GET_MODE (x);
1690 hash += (unsigned) code + (unsigned) GET_MODE (x);
1691 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1695 /* If we are about to do the last recursive call
1696 needed at this level, change it into iteration.
1697 This function is called enough to be worth it. */
1704 hash += hash_expr_1 (XEXP (x, i), 0, do_not_record_p);
1705 if (*do_not_record_p)
1709 else if (fmt[i] == 'E')
1710 for (j = 0; j < XVECLEN (x, i); j++)
1712 hash += hash_expr_1 (XVECEXP (x, i, j), 0, do_not_record_p);
1713 if (*do_not_record_p)
1717 else if (fmt[i] == 's')
1718 hash += hash_string_1 (XSTR (x, i));
1719 else if (fmt[i] == 'i')
1720 hash += (unsigned int) XINT (x, i);
1728 /* Hash a set of register REGNO.
1730 Sets are hashed on the register that is set. This simplifies the PRE copy
1733 ??? May need to make things more elaborate. Later, as necessary. */
1736 hash_set (int regno, int hash_table_size)
1741 return hash % hash_table_size;
1744 /* Return nonzero if exp1 is equivalent to exp2.
1745 ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
1748 expr_equiv_p (rtx x, rtx y)
1757 if (x == 0 || y == 0)
1760 code = GET_CODE (x);
1761 if (code != GET_CODE (y))
1764 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
1765 if (GET_MODE (x) != GET_MODE (y))
1776 return XEXP (x, 0) == XEXP (y, 0);
1779 return XSTR (x, 0) == XSTR (y, 0);
1782 return REGNO (x) == REGNO (y);
1785 /* Can't merge two expressions in different alias sets, since we can
1786 decide that the expression is transparent in a block when it isn't,
1787 due to it being set with the different alias set. */
1788 if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
1791 /* A volatile mem should not be considered equivalent to any other. */
1792 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
1796 /* For commutative operations, check both orders. */
1804 return ((expr_equiv_p (XEXP (x, 0), XEXP (y, 0))
1805 && expr_equiv_p (XEXP (x, 1), XEXP (y, 1)))
1806 || (expr_equiv_p (XEXP (x, 0), XEXP (y, 1))
1807 && expr_equiv_p (XEXP (x, 1), XEXP (y, 0))));
1810 /* We don't use the generic code below because we want to
1811 disregard filename and line numbers. */
1813 /* A volatile asm isn't equivalent to any other. */
1814 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
1817 if (GET_MODE (x) != GET_MODE (y)
1818 || strcmp (ASM_OPERANDS_TEMPLATE (x), ASM_OPERANDS_TEMPLATE (y))
1819 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x),
1820 ASM_OPERANDS_OUTPUT_CONSTRAINT (y))
1821 || ASM_OPERANDS_OUTPUT_IDX (x) != ASM_OPERANDS_OUTPUT_IDX (y)
1822 || ASM_OPERANDS_INPUT_LENGTH (x) != ASM_OPERANDS_INPUT_LENGTH (y))
1825 if (ASM_OPERANDS_INPUT_LENGTH (x))
1827 for (i = ASM_OPERANDS_INPUT_LENGTH (x) - 1; i >= 0; i--)
1828 if (! expr_equiv_p (ASM_OPERANDS_INPUT (x, i),
1829 ASM_OPERANDS_INPUT (y, i))
1830 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x, i),
1831 ASM_OPERANDS_INPUT_CONSTRAINT (y, i)))
1841 /* Compare the elements. If any pair of corresponding elements
1842 fail to match, return 0 for the whole thing. */
1844 fmt = GET_RTX_FORMAT (code);
1845 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1850 if (! expr_equiv_p (XEXP (x, i), XEXP (y, i)))
1855 if (XVECLEN (x, i) != XVECLEN (y, i))
1857 for (j = 0; j < XVECLEN (x, i); j++)
1858 if (! expr_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
1863 if (strcmp (XSTR (x, i), XSTR (y, i)))
1868 if (XINT (x, i) != XINT (y, i))
1873 if (XWINT (x, i) != XWINT (y, i))
1888 /* Insert expression X in INSN in the hash TABLE.
1889 If it is already present, record it as the last occurrence in INSN's
1892 MODE is the mode of the value X is being stored into.
1893 It is only used if X is a CONST_INT.
1895 ANTIC_P is nonzero if X is an anticipatable expression.
1896 AVAIL_P is nonzero if X is an available expression. */
1899 insert_expr_in_table (rtx x, enum machine_mode mode, rtx insn, int antic_p,
1900 int avail_p, struct hash_table *table)
1902 int found, do_not_record_p;
1904 struct expr *cur_expr, *last_expr = NULL;
1905 struct occr *antic_occr, *avail_occr;
1906 struct occr *last_occr = NULL;
1908 hash = hash_expr (x, mode, &do_not_record_p, table->size);
1910 /* Do not insert expression in table if it contains volatile operands,
1911 or if hash_expr determines the expression is something we don't want
1912 to or can't handle. */
1913 if (do_not_record_p)
1916 cur_expr = table->table[hash];
1919 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
1921 /* If the expression isn't found, save a pointer to the end of
1923 last_expr = cur_expr;
1924 cur_expr = cur_expr->next_same_hash;
1929 cur_expr = gcse_alloc (sizeof (struct expr));
1930 bytes_used += sizeof (struct expr);
1931 if (table->table[hash] == NULL)
1932 /* This is the first pattern that hashed to this index. */
1933 table->table[hash] = cur_expr;
1935 /* Add EXPR to end of this hash chain. */
1936 last_expr->next_same_hash = cur_expr;
1938 /* Set the fields of the expr element. */
1940 cur_expr->bitmap_index = table->n_elems++;
1941 cur_expr->next_same_hash = NULL;
1942 cur_expr->antic_occr = NULL;
1943 cur_expr->avail_occr = NULL;
1946 /* Now record the occurrence(s). */
1949 antic_occr = cur_expr->antic_occr;
1951 /* Search for another occurrence in the same basic block. */
1952 while (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn))
1954 /* If an occurrence isn't found, save a pointer to the end of
1956 last_occr = antic_occr;
1957 antic_occr = antic_occr->next;
1961 /* Found another instance of the expression in the same basic block.
1962 Prefer the currently recorded one. We want the first one in the
1963 block and the block is scanned from start to end. */
1964 ; /* nothing to do */
1967 /* First occurrence of this expression in this basic block. */
1968 antic_occr = gcse_alloc (sizeof (struct occr));
1969 bytes_used += sizeof (struct occr);
1970 /* First occurrence of this expression in any block? */
1971 if (cur_expr->antic_occr == NULL)
1972 cur_expr->antic_occr = antic_occr;
1974 last_occr->next = antic_occr;
1976 antic_occr->insn = insn;
1977 antic_occr->next = NULL;
1983 avail_occr = cur_expr->avail_occr;
1985 /* Search for another occurrence in the same basic block. */
1986 while (avail_occr && BLOCK_NUM (avail_occr->insn) != BLOCK_NUM (insn))
1988 /* If an occurrence isn't found, save a pointer to the end of
1990 last_occr = avail_occr;
1991 avail_occr = avail_occr->next;
1995 /* Found another instance of the expression in the same basic block.
1996 Prefer this occurrence to the currently recorded one. We want
1997 the last one in the block and the block is scanned from start
1999 avail_occr->insn = insn;
2002 /* First occurrence of this expression in this basic block. */
2003 avail_occr = gcse_alloc (sizeof (struct occr));
2004 bytes_used += sizeof (struct occr);
2006 /* First occurrence of this expression in any block? */
2007 if (cur_expr->avail_occr == NULL)
2008 cur_expr->avail_occr = avail_occr;
2010 last_occr->next = avail_occr;
2012 avail_occr->insn = insn;
2013 avail_occr->next = NULL;
2018 /* Insert pattern X in INSN in the hash table.
2019 X is a SET of a reg to either another reg or a constant.
2020 If it is already present, record it as the last occurrence in INSN's
2024 insert_set_in_table (rtx x, rtx insn, struct hash_table *table)
2028 struct expr *cur_expr, *last_expr = NULL;
2029 struct occr *cur_occr, *last_occr = NULL;
2031 if (GET_CODE (x) != SET
2032 || GET_CODE (SET_DEST (x)) != REG)
2035 hash = hash_set (REGNO (SET_DEST (x)), table->size);
2037 cur_expr = table->table[hash];
2040 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
2042 /* If the expression isn't found, save a pointer to the end of
2044 last_expr = cur_expr;
2045 cur_expr = cur_expr->next_same_hash;
2050 cur_expr = gcse_alloc (sizeof (struct expr));
2051 bytes_used += sizeof (struct expr);
2052 if (table->table[hash] == NULL)
2053 /* This is the first pattern that hashed to this index. */
2054 table->table[hash] = cur_expr;
2056 /* Add EXPR to end of this hash chain. */
2057 last_expr->next_same_hash = cur_expr;
2059 /* Set the fields of the expr element.
2060 We must copy X because it can be modified when copy propagation is
2061 performed on its operands. */
2062 cur_expr->expr = copy_rtx (x);
2063 cur_expr->bitmap_index = table->n_elems++;
2064 cur_expr->next_same_hash = NULL;
2065 cur_expr->antic_occr = NULL;
2066 cur_expr->avail_occr = NULL;
2069 /* Now record the occurrence. */
2070 cur_occr = cur_expr->avail_occr;
2072 /* Search for another occurrence in the same basic block. */
2073 while (cur_occr && BLOCK_NUM (cur_occr->insn) != BLOCK_NUM (insn))
2075 /* If an occurrence isn't found, save a pointer to the end of
2077 last_occr = cur_occr;
2078 cur_occr = cur_occr->next;
2082 /* Found another instance of the expression in the same basic block.
2083 Prefer this occurrence to the currently recorded one. We want the
2084 last one in the block and the block is scanned from start to end. */
2085 cur_occr->insn = insn;
2088 /* First occurrence of this expression in this basic block. */
2089 cur_occr = gcse_alloc (sizeof (struct occr));
2090 bytes_used += sizeof (struct occr);
2092 /* First occurrence of this expression in any block? */
2093 if (cur_expr->avail_occr == NULL)
2094 cur_expr->avail_occr = cur_occr;
2096 last_occr->next = cur_occr;
2098 cur_occr->insn = insn;
2099 cur_occr->next = NULL;
2103 /* Determine whether the rtx X should be treated as a constant for
2104 the purposes of GCSE's constant propagation. */
2107 gcse_constant_p (rtx x)
2109 /* Consider a COMPARE of two integers constant. */
2110 if (GET_CODE (x) == COMPARE
2111 && GET_CODE (XEXP (x, 0)) == CONST_INT
2112 && GET_CODE (XEXP (x, 1)) == CONST_INT)
2116 /* Consider a COMPARE of the same registers is a constant
2117 if they are not floating point registers. */
2118 if (GET_CODE(x) == COMPARE
2119 && GET_CODE (XEXP (x, 0)) == REG
2120 && GET_CODE (XEXP (x, 1)) == REG
2121 && REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 1))
2122 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 0)))
2123 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 1))))
2126 if (GET_CODE (x) == CONSTANT_P_RTX)
2129 return CONSTANT_P (x);
2132 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
2136 hash_scan_set (rtx pat, rtx insn, struct hash_table *table)
2138 rtx src = SET_SRC (pat);
2139 rtx dest = SET_DEST (pat);
2142 if (GET_CODE (src) == CALL)
2143 hash_scan_call (src, insn, table);
2145 else if (GET_CODE (dest) == REG)
2147 unsigned int regno = REGNO (dest);
2150 /* If this is a single set and we are doing constant propagation,
2151 see if a REG_NOTE shows this equivalent to a constant. */
2152 if (table->set_p && (note = find_reg_equal_equiv_note (insn)) != 0
2153 && gcse_constant_p (XEXP (note, 0)))
2154 src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src);
2156 /* Only record sets of pseudo-regs in the hash table. */
2158 && regno >= FIRST_PSEUDO_REGISTER
2159 /* Don't GCSE something if we can't do a reg/reg copy. */
2160 && can_copy_p (GET_MODE (dest))
2161 /* GCSE commonly inserts instruction after the insn. We can't
2162 do that easily for EH_REGION notes so disable GCSE on these
2164 && !find_reg_note (insn, REG_EH_REGION, NULL_RTX)
2165 /* Is SET_SRC something we want to gcse? */
2166 && want_to_gcse_p (src)
2167 /* Don't CSE a nop. */
2168 && ! set_noop_p (pat)
2169 /* Don't GCSE if it has attached REG_EQUIV note.
2170 At this point this only function parameters should have
2171 REG_EQUIV notes and if the argument slot is used somewhere
2172 explicitly, it means address of parameter has been taken,
2173 so we should not extend the lifetime of the pseudo. */
2174 && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
2175 || GET_CODE (XEXP (note, 0)) != MEM))
2177 /* An expression is not anticipatable if its operands are
2178 modified before this insn or if this is not the only SET in
2180 int antic_p = oprs_anticipatable_p (src, insn) && single_set (insn);
2181 /* An expression is not available if its operands are
2182 subsequently modified, including this insn. It's also not
2183 available if this is a branch, because we can't insert
2184 a set after the branch. */
2185 int avail_p = (oprs_available_p (src, insn)
2186 && ! JUMP_P (insn));
2188 insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p, table);
2191 /* Record sets for constant/copy propagation. */
2192 else if (table->set_p
2193 && regno >= FIRST_PSEUDO_REGISTER
2194 && ((GET_CODE (src) == REG
2195 && REGNO (src) >= FIRST_PSEUDO_REGISTER
2196 && can_copy_p (GET_MODE (dest))
2197 && REGNO (src) != regno)
2198 || gcse_constant_p (src))
2199 /* A copy is not available if its src or dest is subsequently
2200 modified. Here we want to search from INSN+1 on, but
2201 oprs_available_p searches from INSN on. */
2202 && (insn == BLOCK_END (BLOCK_NUM (insn))
2203 || ((tmp = next_nonnote_insn (insn)) != NULL_RTX
2204 && oprs_available_p (pat, tmp))))
2205 insert_set_in_table (pat, insn, table);
2210 hash_scan_clobber (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
2211 struct hash_table *table ATTRIBUTE_UNUSED)
2213 /* Currently nothing to do. */
2217 hash_scan_call (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
2218 struct hash_table *table ATTRIBUTE_UNUSED)
2220 /* Currently nothing to do. */
2223 /* Process INSN and add hash table entries as appropriate.
2225 Only available expressions that set a single pseudo-reg are recorded.
2227 Single sets in a PARALLEL could be handled, but it's an extra complication
2228 that isn't dealt with right now. The trick is handling the CLOBBERs that
2229 are also in the PARALLEL. Later.
2231 If SET_P is nonzero, this is for the assignment hash table,
2232 otherwise it is for the expression hash table.
2233 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
2234 not record any expressions. */
2237 hash_scan_insn (rtx insn, struct hash_table *table, int in_libcall_block)
2239 rtx pat = PATTERN (insn);
2242 if (in_libcall_block)
2245 /* Pick out the sets of INSN and for other forms of instructions record
2246 what's been modified. */
2248 if (GET_CODE (pat) == SET)
2249 hash_scan_set (pat, insn, table);
2250 else if (GET_CODE (pat) == PARALLEL)
2251 for (i = 0; i < XVECLEN (pat, 0); i++)
2253 rtx x = XVECEXP (pat, 0, i);
2255 if (GET_CODE (x) == SET)
2256 hash_scan_set (x, insn, table);
2257 else if (GET_CODE (x) == CLOBBER)
2258 hash_scan_clobber (x, insn, table);
2259 else if (GET_CODE (x) == CALL)
2260 hash_scan_call (x, insn, table);
2263 else if (GET_CODE (pat) == CLOBBER)
2264 hash_scan_clobber (pat, insn, table);
2265 else if (GET_CODE (pat) == CALL)
2266 hash_scan_call (pat, insn, table);
2270 dump_hash_table (FILE *file, const char *name, struct hash_table *table)
2273 /* Flattened out table, so it's printed in proper order. */
2274 struct expr **flat_table;
2275 unsigned int *hash_val;
2278 flat_table = xcalloc (table->n_elems, sizeof (struct expr *));
2279 hash_val = xmalloc (table->n_elems * sizeof (unsigned int));
2281 for (i = 0; i < (int) table->size; i++)
2282 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
2284 flat_table[expr->bitmap_index] = expr;
2285 hash_val[expr->bitmap_index] = i;
2288 fprintf (file, "%s hash table (%d buckets, %d entries)\n",
2289 name, table->size, table->n_elems);
2291 for (i = 0; i < (int) table->n_elems; i++)
2292 if (flat_table[i] != 0)
2294 expr = flat_table[i];
2295 fprintf (file, "Index %d (hash value %d)\n ",
2296 expr->bitmap_index, hash_val[i]);
2297 print_rtl (file, expr->expr);
2298 fprintf (file, "\n");
2301 fprintf (file, "\n");
2307 /* Record register first/last/block set information for REGNO in INSN.
2309 first_set records the first place in the block where the register
2310 is set and is used to compute "anticipatability".
2312 last_set records the last place in the block where the register
2313 is set and is used to compute "availability".
2315 last_bb records the block for which first_set and last_set are
2316 valid, as a quick test to invalidate them.
2318 reg_set_in_block records whether the register is set in the block
2319 and is used to compute "transparency". */
2322 record_last_reg_set_info (rtx insn, int regno)
2324 struct reg_avail_info *info = ®_avail_info[regno];
2325 int cuid = INSN_CUID (insn);
2327 info->last_set = cuid;
2328 if (info->last_bb != current_bb)
2330 info->last_bb = current_bb;
2331 info->first_set = cuid;
2332 SET_BIT (reg_set_in_block[current_bb->index], regno);
2337 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
2338 Note we store a pair of elements in the list, so they have to be
2339 taken off pairwise. */
2342 canon_list_insert (rtx dest ATTRIBUTE_UNUSED, rtx unused1 ATTRIBUTE_UNUSED,
2345 rtx dest_addr, insn;
2348 while (GET_CODE (dest) == SUBREG
2349 || GET_CODE (dest) == ZERO_EXTRACT
2350 || GET_CODE (dest) == SIGN_EXTRACT
2351 || GET_CODE (dest) == STRICT_LOW_PART)
2352 dest = XEXP (dest, 0);
2354 /* If DEST is not a MEM, then it will not conflict with a load. Note
2355 that function calls are assumed to clobber memory, but are handled
2358 if (GET_CODE (dest) != MEM)
2361 dest_addr = get_addr (XEXP (dest, 0));
2362 dest_addr = canon_rtx (dest_addr);
2363 insn = (rtx) v_insn;
2364 bb = BLOCK_NUM (insn);
2366 canon_modify_mem_list[bb] =
2367 alloc_EXPR_LIST (VOIDmode, dest_addr, canon_modify_mem_list[bb]);
2368 canon_modify_mem_list[bb] =
2369 alloc_EXPR_LIST (VOIDmode, dest, canon_modify_mem_list[bb]);
2370 bitmap_set_bit (canon_modify_mem_list_set, bb);
2373 /* Record memory modification information for INSN. We do not actually care
2374 about the memory location(s) that are set, or even how they are set (consider
2375 a CALL_INSN). We merely need to record which insns modify memory. */
2378 record_last_mem_set_info (rtx insn)
2380 int bb = BLOCK_NUM (insn);
2382 /* load_killed_in_block_p will handle the case of calls clobbering
2384 modify_mem_list[bb] = alloc_INSN_LIST (insn, modify_mem_list[bb]);
2385 bitmap_set_bit (modify_mem_list_set, bb);
2387 if (GET_CODE (insn) == CALL_INSN)
2389 /* Note that traversals of this loop (other than for free-ing)
2390 will break after encountering a CALL_INSN. So, there's no
2391 need to insert a pair of items, as canon_list_insert does. */
2392 canon_modify_mem_list[bb] =
2393 alloc_INSN_LIST (insn, canon_modify_mem_list[bb]);
2394 bitmap_set_bit (canon_modify_mem_list_set, bb);
2397 note_stores (PATTERN (insn), canon_list_insert, (void*) insn);
2400 /* Called from compute_hash_table via note_stores to handle one
2401 SET or CLOBBER in an insn. DATA is really the instruction in which
2402 the SET is taking place. */
2405 record_last_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
2407 rtx last_set_insn = (rtx) data;
2409 if (GET_CODE (dest) == SUBREG)
2410 dest = SUBREG_REG (dest);
2412 if (GET_CODE (dest) == REG)
2413 record_last_reg_set_info (last_set_insn, REGNO (dest));
2414 else if (GET_CODE (dest) == MEM
2415 /* Ignore pushes, they clobber nothing. */
2416 && ! push_operand (dest, GET_MODE (dest)))
2417 record_last_mem_set_info (last_set_insn);
2420 /* Top level function to create an expression or assignment hash table.
2422 Expression entries are placed in the hash table if
2423 - they are of the form (set (pseudo-reg) src),
2424 - src is something we want to perform GCSE on,
2425 - none of the operands are subsequently modified in the block
2427 Assignment entries are placed in the hash table if
2428 - they are of the form (set (pseudo-reg) src),
2429 - src is something we want to perform const/copy propagation on,
2430 - none of the operands or target are subsequently modified in the block
2432 Currently src must be a pseudo-reg or a const_int.
2434 TABLE is the table computed. */
2437 compute_hash_table_work (struct hash_table *table)
2441 /* While we compute the hash table we also compute a bit array of which
2442 registers are set in which blocks.
2443 ??? This isn't needed during const/copy propagation, but it's cheap to
2445 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
2447 /* re-Cache any INSN_LIST nodes we have allocated. */
2448 clear_modify_mem_tables ();
2449 /* Some working arrays used to track first and last set in each block. */
2450 reg_avail_info = gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
2452 for (i = 0; i < max_gcse_regno; ++i)
2453 reg_avail_info[i].last_bb = NULL;
2455 FOR_EACH_BB (current_bb)
2459 int in_libcall_block;
2461 /* First pass over the instructions records information used to
2462 determine when registers and memory are first and last set.
2463 ??? hard-reg reg_set_in_block computation
2464 could be moved to compute_sets since they currently don't change. */
2466 for (insn = current_bb->head;
2467 insn && insn != NEXT_INSN (current_bb->end);
2468 insn = NEXT_INSN (insn))
2470 if (! INSN_P (insn))
2473 if (GET_CODE (insn) == CALL_INSN)
2475 bool clobbers_all = false;
2476 #ifdef NON_SAVING_SETJMP
2477 if (NON_SAVING_SETJMP
2478 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
2479 clobbers_all = true;
2482 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2484 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2485 record_last_reg_set_info (insn, regno);
2490 note_stores (PATTERN (insn), record_last_set_info, insn);
2493 /* Insert implicit sets in the hash table. */
2495 && implicit_sets[current_bb->index] != NULL_RTX)
2496 hash_scan_set (implicit_sets[current_bb->index],
2497 current_bb->head, table);
2499 /* The next pass builds the hash table. */
2501 for (insn = current_bb->head, in_libcall_block = 0;
2502 insn && insn != NEXT_INSN (current_bb->end);
2503 insn = NEXT_INSN (insn))
2506 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2507 in_libcall_block = 1;
2508 else if (table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2509 in_libcall_block = 0;
2510 hash_scan_insn (insn, table, in_libcall_block);
2511 if (!table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2512 in_libcall_block = 0;
2516 free (reg_avail_info);
2517 reg_avail_info = NULL;
2520 /* Allocate space for the set/expr hash TABLE.
2521 N_INSNS is the number of instructions in the function.
2522 It is used to determine the number of buckets to use.
2523 SET_P determines whether set or expression table will
2527 alloc_hash_table (int n_insns, struct hash_table *table, int set_p)
2531 table->size = n_insns / 4;
2532 if (table->size < 11)
2535 /* Attempt to maintain efficient use of hash table.
2536 Making it an odd number is simplest for now.
2537 ??? Later take some measurements. */
2539 n = table->size * sizeof (struct expr *);
2540 table->table = gmalloc (n);
2541 table->set_p = set_p;
2544 /* Free things allocated by alloc_hash_table. */
2547 free_hash_table (struct hash_table *table)
2549 free (table->table);
2552 /* Compute the hash TABLE for doing copy/const propagation or
2553 expression hash table. */
2556 compute_hash_table (struct hash_table *table)
2558 /* Initialize count of number of entries in hash table. */
2560 memset (table->table, 0, table->size * sizeof (struct expr *));
2562 compute_hash_table_work (table);
2565 /* Expression tracking support. */
2567 /* Lookup pattern PAT in the expression TABLE.
2568 The result is a pointer to the table entry, or NULL if not found. */
2570 static struct expr *
2571 lookup_expr (rtx pat, struct hash_table *table)
2573 int do_not_record_p;
2574 unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p,
2578 if (do_not_record_p)
2581 expr = table->table[hash];
2583 while (expr && ! expr_equiv_p (expr->expr, pat))
2584 expr = expr->next_same_hash;
2589 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2590 table entry, or NULL if not found. */
2592 static struct expr *
2593 lookup_set (unsigned int regno, struct hash_table *table)
2595 unsigned int hash = hash_set (regno, table->size);
2598 expr = table->table[hash];
2600 while (expr && REGNO (SET_DEST (expr->expr)) != regno)
2601 expr = expr->next_same_hash;
2606 /* Return the next entry for REGNO in list EXPR. */
2608 static struct expr *
2609 next_set (unsigned int regno, struct expr *expr)
2612 expr = expr->next_same_hash;
2613 while (expr && REGNO (SET_DEST (expr->expr)) != regno);
2618 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2619 types may be mixed. */
2622 free_insn_expr_list_list (rtx *listp)
2626 for (list = *listp; list ; list = next)
2628 next = XEXP (list, 1);
2629 if (GET_CODE (list) == EXPR_LIST)
2630 free_EXPR_LIST_node (list);
2632 free_INSN_LIST_node (list);
2638 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2640 clear_modify_mem_tables (void)
2644 EXECUTE_IF_SET_IN_BITMAP
2645 (modify_mem_list_set, 0, i, free_INSN_LIST_list (modify_mem_list + i));
2646 bitmap_clear (modify_mem_list_set);
2648 EXECUTE_IF_SET_IN_BITMAP
2649 (canon_modify_mem_list_set, 0, i,
2650 free_insn_expr_list_list (canon_modify_mem_list + i));
2651 bitmap_clear (canon_modify_mem_list_set);
2654 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2657 free_modify_mem_tables (void)
2659 clear_modify_mem_tables ();
2660 free (modify_mem_list);
2661 free (canon_modify_mem_list);
2662 modify_mem_list = 0;
2663 canon_modify_mem_list = 0;
2666 /* Reset tables used to keep track of what's still available [since the
2667 start of the block]. */
2670 reset_opr_set_tables (void)
2672 /* Maintain a bitmap of which regs have been set since beginning of
2674 CLEAR_REG_SET (reg_set_bitmap);
2676 /* Also keep a record of the last instruction to modify memory.
2677 For now this is very trivial, we only record whether any memory
2678 location has been modified. */
2679 clear_modify_mem_tables ();
2682 /* Return nonzero if the operands of X are not set before INSN in
2683 INSN's basic block. */
2686 oprs_not_set_p (rtx x, rtx insn)
2695 code = GET_CODE (x);
2711 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn),
2712 INSN_CUID (insn), x, 0))
2715 return oprs_not_set_p (XEXP (x, 0), insn);
2718 return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x));
2724 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2728 /* If we are about to do the last recursive call
2729 needed at this level, change it into iteration.
2730 This function is called enough to be worth it. */
2732 return oprs_not_set_p (XEXP (x, i), insn);
2734 if (! oprs_not_set_p (XEXP (x, i), insn))
2737 else if (fmt[i] == 'E')
2738 for (j = 0; j < XVECLEN (x, i); j++)
2739 if (! oprs_not_set_p (XVECEXP (x, i, j), insn))
2746 /* Mark things set by a CALL. */
2749 mark_call (rtx insn)
2751 if (! CONST_OR_PURE_CALL_P (insn))
2752 record_last_mem_set_info (insn);
2755 /* Mark things set by a SET. */
2758 mark_set (rtx pat, rtx insn)
2760 rtx dest = SET_DEST (pat);
2762 while (GET_CODE (dest) == SUBREG
2763 || GET_CODE (dest) == ZERO_EXTRACT
2764 || GET_CODE (dest) == SIGN_EXTRACT
2765 || GET_CODE (dest) == STRICT_LOW_PART)
2766 dest = XEXP (dest, 0);
2768 if (GET_CODE (dest) == REG)
2769 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (dest));
2770 else if (GET_CODE (dest) == MEM)
2771 record_last_mem_set_info (insn);
2773 if (GET_CODE (SET_SRC (pat)) == CALL)
2777 /* Record things set by a CLOBBER. */
2780 mark_clobber (rtx pat, rtx insn)
2782 rtx clob = XEXP (pat, 0);
2784 while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART)
2785 clob = XEXP (clob, 0);
2787 if (GET_CODE (clob) == REG)
2788 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (clob));
2790 record_last_mem_set_info (insn);
2793 /* Record things set by INSN.
2794 This data is used by oprs_not_set_p. */
2797 mark_oprs_set (rtx insn)
2799 rtx pat = PATTERN (insn);
2802 if (GET_CODE (pat) == SET)
2803 mark_set (pat, insn);
2804 else if (GET_CODE (pat) == PARALLEL)
2805 for (i = 0; i < XVECLEN (pat, 0); i++)
2807 rtx x = XVECEXP (pat, 0, i);
2809 if (GET_CODE (x) == SET)
2811 else if (GET_CODE (x) == CLOBBER)
2812 mark_clobber (x, insn);
2813 else if (GET_CODE (x) == CALL)
2817 else if (GET_CODE (pat) == CLOBBER)
2818 mark_clobber (pat, insn);
2819 else if (GET_CODE (pat) == CALL)
2824 /* Classic GCSE reaching definition support. */
2826 /* Allocate reaching def variables. */
2829 alloc_rd_mem (int n_blocks, int n_insns)
2831 rd_kill = sbitmap_vector_alloc (n_blocks, n_insns);
2832 sbitmap_vector_zero (rd_kill, n_blocks);
2834 rd_gen = sbitmap_vector_alloc (n_blocks, n_insns);
2835 sbitmap_vector_zero (rd_gen, n_blocks);
2837 reaching_defs = sbitmap_vector_alloc (n_blocks, n_insns);
2838 sbitmap_vector_zero (reaching_defs, n_blocks);
2840 rd_out = sbitmap_vector_alloc (n_blocks, n_insns);
2841 sbitmap_vector_zero (rd_out, n_blocks);
2844 /* Free reaching def variables. */
2849 sbitmap_vector_free (rd_kill);
2850 sbitmap_vector_free (rd_gen);
2851 sbitmap_vector_free (reaching_defs);
2852 sbitmap_vector_free (rd_out);
2855 /* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
2858 handle_rd_kill_set (rtx insn, int regno, basic_block bb)
2860 struct reg_set *this_reg;
2862 for (this_reg = reg_set_table[regno]; this_reg; this_reg = this_reg ->next)
2863 if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn))
2864 SET_BIT (rd_kill[bb->index], INSN_CUID (this_reg->insn));
2867 /* Compute the set of kill's for reaching definitions. */
2870 compute_kill_rd (void)
2878 For each set bit in `gen' of the block (i.e each insn which
2879 generates a definition in the block)
2880 Call the reg set by the insn corresponding to that bit regx
2881 Look at the linked list starting at reg_set_table[regx]
2882 For each setting of regx in the linked list, which is not in
2884 Set the bit in `kill' corresponding to that insn. */
2886 for (cuid = 0; cuid < max_cuid; cuid++)
2887 if (TEST_BIT (rd_gen[bb->index], cuid))
2889 rtx insn = CUID_INSN (cuid);
2890 rtx pat = PATTERN (insn);
2892 if (GET_CODE (insn) == CALL_INSN)
2894 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2895 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2896 handle_rd_kill_set (insn, regno, bb);
2899 if (GET_CODE (pat) == PARALLEL)
2901 for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
2903 enum rtx_code code = GET_CODE (XVECEXP (pat, 0, i));
2905 if ((code == SET || code == CLOBBER)
2906 && GET_CODE (XEXP (XVECEXP (pat, 0, i), 0)) == REG)
2907 handle_rd_kill_set (insn,
2908 REGNO (XEXP (XVECEXP (pat, 0, i), 0)),
2912 else if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == REG)
2913 /* Each setting of this register outside of this block
2914 must be marked in the set of kills in this block. */
2915 handle_rd_kill_set (insn, REGNO (SET_DEST (pat)), bb);
2919 /* Compute the reaching definitions as in
2920 Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
2921 Chapter 10. It is the same algorithm as used for computing available
2922 expressions but applied to the gens and kills of reaching definitions. */
2927 int changed, passes;
2931 sbitmap_copy (rd_out[bb->index] /*dst*/, rd_gen[bb->index] /*src*/);
2940 sbitmap_union_of_preds (reaching_defs[bb->index], rd_out, bb->index);
2941 changed |= sbitmap_union_of_diff_cg (rd_out[bb->index], rd_gen[bb->index],
2942 reaching_defs[bb->index], rd_kill[bb->index]);
2948 fprintf (gcse_file, "reaching def computation: %d passes\n", passes);
2951 /* Classic GCSE available expression support. */
2953 /* Allocate memory for available expression computation. */
2956 alloc_avail_expr_mem (int n_blocks, int n_exprs)
2958 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
2959 sbitmap_vector_zero (ae_kill, n_blocks);
2961 ae_gen = sbitmap_vector_alloc (n_blocks, n_exprs);
2962 sbitmap_vector_zero (ae_gen, n_blocks);
2964 ae_in = sbitmap_vector_alloc (n_blocks, n_exprs);
2965 sbitmap_vector_zero (ae_in, n_blocks);
2967 ae_out = sbitmap_vector_alloc (n_blocks, n_exprs);
2968 sbitmap_vector_zero (ae_out, n_blocks);
2972 free_avail_expr_mem (void)
2974 sbitmap_vector_free (ae_kill);
2975 sbitmap_vector_free (ae_gen);
2976 sbitmap_vector_free (ae_in);
2977 sbitmap_vector_free (ae_out);
2980 /* Compute the set of available expressions generated in each basic block. */
2983 compute_ae_gen (struct hash_table *expr_hash_table)
2989 /* For each recorded occurrence of each expression, set ae_gen[bb][expr].
2990 This is all we have to do because an expression is not recorded if it
2991 is not available, and the only expressions we want to work with are the
2992 ones that are recorded. */
2993 for (i = 0; i < expr_hash_table->size; i++)
2994 for (expr = expr_hash_table->table[i]; expr != 0; expr = expr->next_same_hash)
2995 for (occr = expr->avail_occr; occr != 0; occr = occr->next)
2996 SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index);
2999 /* Return nonzero if expression X is killed in BB. */
3002 expr_killed_p (rtx x, basic_block bb)
3011 code = GET_CODE (x);
3015 return TEST_BIT (reg_set_in_block[bb->index], REGNO (x));
3018 if (load_killed_in_block_p (bb, get_max_uid () + 1, x, 0))
3021 return expr_killed_p (XEXP (x, 0), bb);
3039 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3043 /* If we are about to do the last recursive call
3044 needed at this level, change it into iteration.
3045 This function is called enough to be worth it. */
3047 return expr_killed_p (XEXP (x, i), bb);
3048 else if (expr_killed_p (XEXP (x, i), bb))
3051 else if (fmt[i] == 'E')
3052 for (j = 0; j < XVECLEN (x, i); j++)
3053 if (expr_killed_p (XVECEXP (x, i, j), bb))
3060 /* Compute the set of available expressions killed in each basic block. */
3063 compute_ae_kill (sbitmap *ae_gen, sbitmap *ae_kill,
3064 struct hash_table *expr_hash_table)
3071 for (i = 0; i < expr_hash_table->size; i++)
3072 for (expr = expr_hash_table->table[i]; expr; expr = expr->next_same_hash)
3074 /* Skip EXPR if generated in this block. */
3075 if (TEST_BIT (ae_gen[bb->index], expr->bitmap_index))
3078 if (expr_killed_p (expr->expr, bb))
3079 SET_BIT (ae_kill[bb->index], expr->bitmap_index);
3083 /* Actually perform the Classic GCSE optimizations. */
3085 /* Return nonzero if occurrence OCCR of expression EXPR reaches block BB.
3087 CHECK_SELF_LOOP is nonzero if we should consider a block reaching itself
3088 as a positive reach. We want to do this when there are two computations
3089 of the expression in the block.
3091 VISITED is a pointer to a working buffer for tracking which BB's have
3092 been visited. It is NULL for the top-level call.
3094 We treat reaching expressions that go through blocks containing the same
3095 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3096 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3097 2 as not reaching. The intent is to improve the probability of finding
3098 only one reaching expression and to reduce register lifetimes by picking
3099 the closest such expression. */
3102 expr_reaches_here_p_work (struct occr *occr, struct expr *expr,
3103 basic_block bb, int check_self_loop, char *visited)
3107 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
3109 basic_block pred_bb = pred->src;
3111 if (visited[pred_bb->index])
3112 /* This predecessor has already been visited. Nothing to do. */
3114 else if (pred_bb == bb)
3116 /* BB loops on itself. */
3118 && TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index)
3119 && BLOCK_NUM (occr->insn) == pred_bb->index)
3122 visited[pred_bb->index] = 1;
3125 /* Ignore this predecessor if it kills the expression. */
3126 else if (TEST_BIT (ae_kill[pred_bb->index], expr->bitmap_index))
3127 visited[pred_bb->index] = 1;
3129 /* Does this predecessor generate this expression? */
3130 else if (TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index))
3132 /* Is this the occurrence we're looking for?
3133 Note that there's only one generating occurrence per block
3134 so we just need to check the block number. */
3135 if (BLOCK_NUM (occr->insn) == pred_bb->index)
3138 visited[pred_bb->index] = 1;
3141 /* Neither gen nor kill. */
3144 visited[pred_bb->index] = 1;
3145 if (expr_reaches_here_p_work (occr, expr, pred_bb, check_self_loop,
3152 /* All paths have been checked. */
3156 /* This wrapper for expr_reaches_here_p_work() is to ensure that any
3157 memory allocated for that function is returned. */
3160 expr_reaches_here_p (struct occr *occr, struct expr *expr, basic_block bb,
3161 int check_self_loop)
3164 char *visited = xcalloc (last_basic_block, 1);
3166 rval = expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited);
3172 /* Return the instruction that computes EXPR that reaches INSN's basic block.
3173 If there is more than one such instruction, return NULL.
3175 Called only by handle_avail_expr. */
3178 computing_insn (struct expr *expr, rtx insn)
3180 basic_block bb = BLOCK_FOR_INSN (insn);
3182 if (expr->avail_occr->next == NULL)
3184 if (BLOCK_FOR_INSN (expr->avail_occr->insn) == bb)
3185 /* The available expression is actually itself
3186 (i.e. a loop in the flow graph) so do nothing. */
3189 /* (FIXME) Case that we found a pattern that was created by
3190 a substitution that took place. */
3191 return expr->avail_occr->insn;
3195 /* Pattern is computed more than once.
3196 Search backwards from this insn to see how many of these
3197 computations actually reach this insn. */
3199 rtx insn_computes_expr = NULL;
3202 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
3204 if (BLOCK_FOR_INSN (occr->insn) == bb)
3206 /* The expression is generated in this block.
3207 The only time we care about this is when the expression
3208 is generated later in the block [and thus there's a loop].
3209 We let the normal cse pass handle the other cases. */
3210 if (INSN_CUID (insn) < INSN_CUID (occr->insn)
3211 && expr_reaches_here_p (occr, expr, bb, 1))
3217 insn_computes_expr = occr->insn;
3220 else if (expr_reaches_here_p (occr, expr, bb, 0))
3226 insn_computes_expr = occr->insn;
3230 if (insn_computes_expr == NULL)
3233 return insn_computes_expr;
3237 /* Return nonzero if the definition in DEF_INSN can reach INSN.
3238 Only called by can_disregard_other_sets. */
3241 def_reaches_here_p (rtx insn, rtx def_insn)
3245 if (TEST_BIT (reaching_defs[BLOCK_NUM (insn)], INSN_CUID (def_insn)))
3248 if (BLOCK_NUM (insn) == BLOCK_NUM (def_insn))
3250 if (INSN_CUID (def_insn) < INSN_CUID (insn))
3252 if (GET_CODE (PATTERN (def_insn)) == PARALLEL)
3254 else if (GET_CODE (PATTERN (def_insn)) == CLOBBER)
3255 reg = XEXP (PATTERN (def_insn), 0);
3256 else if (GET_CODE (PATTERN (def_insn)) == SET)
3257 reg = SET_DEST (PATTERN (def_insn));
3261 return ! reg_set_between_p (reg, NEXT_INSN (def_insn), insn);
3270 /* Return nonzero if *ADDR_THIS_REG can only have one value at INSN. The
3271 value returned is the number of definitions that reach INSN. Returning a
3272 value of zero means that [maybe] more than one definition reaches INSN and
3273 the caller can't perform whatever optimization it is trying. i.e. it is
3274 always safe to return zero. */
3277 can_disregard_other_sets (struct reg_set **addr_this_reg, rtx insn, int for_combine)
3279 int number_of_reaching_defs = 0;
3280 struct reg_set *this_reg;
3282 for (this_reg = *addr_this_reg; this_reg != 0; this_reg = this_reg->next)
3283 if (def_reaches_here_p (insn, this_reg->insn))
3285 number_of_reaching_defs++;
3286 /* Ignore parallels for now. */
3287 if (GET_CODE (PATTERN (this_reg->insn)) == PARALLEL)
3291 && (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER
3292 || ! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
3293 SET_SRC (PATTERN (insn)))))
3294 /* A setting of the reg to a different value reaches INSN. */
3297 if (number_of_reaching_defs > 1)
3299 /* If in this setting the value the register is being set to is
3300 equal to the previous value the register was set to and this
3301 setting reaches the insn we are trying to do the substitution
3302 on then we are ok. */
3303 if (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER)
3305 else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
3306 SET_SRC (PATTERN (insn))))
3310 *addr_this_reg = this_reg;
3313 return number_of_reaching_defs;
3316 /* Expression computed by insn is available and the substitution is legal,
3317 so try to perform the substitution.
3319 The result is nonzero if any changes were made. */
3322 handle_avail_expr (rtx insn, struct expr *expr)
3324 rtx pat, insn_computes_expr, expr_set;
3326 struct reg_set *this_reg;
3327 int found_setting, use_src;
3330 /* We only handle the case where one computation of the expression
3331 reaches this instruction. */
3332 insn_computes_expr = computing_insn (expr, insn);
3333 if (insn_computes_expr == NULL)
3335 expr_set = single_set (insn_computes_expr);
3342 /* At this point we know only one computation of EXPR outside of this
3343 block reaches this insn. Now try to find a register that the
3344 expression is computed into. */
3345 if (GET_CODE (SET_SRC (expr_set)) == REG)
3347 /* This is the case when the available expression that reaches
3348 here has already been handled as an available expression. */
3349 unsigned int regnum_for_replacing
3350 = REGNO (SET_SRC (expr_set));
3352 /* If the register was created by GCSE we can't use `reg_set_table',
3353 however we know it's set only once. */
3354 if (regnum_for_replacing >= max_gcse_regno
3355 /* If the register the expression is computed into is set only once,
3356 or only one set reaches this insn, we can use it. */
3357 || (((this_reg = reg_set_table[regnum_for_replacing]),
3358 this_reg->next == NULL)
3359 || can_disregard_other_sets (&this_reg, insn, 0)))
3368 unsigned int regnum_for_replacing
3369 = REGNO (SET_DEST (expr_set));
3371 /* This shouldn't happen. */
3372 if (regnum_for_replacing >= max_gcse_regno)
3375 this_reg = reg_set_table[regnum_for_replacing];
3377 /* If the register the expression is computed into is set only once,
3378 or only one set reaches this insn, use it. */
3379 if (this_reg->next == NULL
3380 || can_disregard_other_sets (&this_reg, insn, 0))
3386 pat = PATTERN (insn);
3388 to = SET_SRC (expr_set);
3390 to = SET_DEST (expr_set);
3391 changed = validate_change (insn, &SET_SRC (pat), to, 0);
3393 /* We should be able to ignore the return code from validate_change but
3394 to play it safe we check. */
3398 if (gcse_file != NULL)
3400 fprintf (gcse_file, "GCSE: Replacing the source in insn %d with",
3402 fprintf (gcse_file, " reg %d %s insn %d\n",
3403 REGNO (to), use_src ? "from" : "set in",
3404 INSN_UID (insn_computes_expr));
3409 /* The register that the expr is computed into is set more than once. */
3410 else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
3412 /* Insert an insn after insnx that copies the reg set in insnx
3413 into a new pseudo register call this new register REGN.
3414 From insnb until end of basic block or until REGB is set
3415 replace all uses of REGB with REGN. */
3418 to = gen_reg_rtx (GET_MODE (SET_DEST (expr_set)));
3420 /* Generate the new insn. */
3421 /* ??? If the change fails, we return 0, even though we created
3422 an insn. I think this is ok. */
3424 = emit_insn_after (gen_rtx_SET (VOIDmode, to,
3425 SET_DEST (expr_set)),
3426 insn_computes_expr);
3428 /* Keep register set table up to date. */
3429 record_one_set (REGNO (to), new_insn);
3431 gcse_create_count++;
3432 if (gcse_file != NULL)
3434 fprintf (gcse_file, "GCSE: Creating insn %d to copy value of reg %d",
3435 INSN_UID (NEXT_INSN (insn_computes_expr)),
3436 REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr)))));
3437 fprintf (gcse_file, ", computed in insn %d,\n",
3438 INSN_UID (insn_computes_expr));
3439 fprintf (gcse_file, " into newly allocated reg %d\n",
3443 pat = PATTERN (insn);
3445 /* Do register replacement for INSN. */
3446 changed = validate_change (insn, &SET_SRC (pat),
3448 (NEXT_INSN (insn_computes_expr))),
3451 /* We should be able to ignore the return code from validate_change but
3452 to play it safe we check. */
3456 if (gcse_file != NULL)
3459 "GCSE: Replacing the source in insn %d with reg %d ",
3461 REGNO (SET_DEST (PATTERN (NEXT_INSN
3462 (insn_computes_expr)))));
3463 fprintf (gcse_file, "set in insn %d\n",
3464 INSN_UID (insn_computes_expr));
3472 /* Perform classic GCSE. This is called by one_classic_gcse_pass after all
3473 the dataflow analysis has been done.
3475 The result is nonzero if a change was made. */
3484 /* Note we start at block 1. */
3486 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
3490 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
3492 /* Reset tables used to keep track of what's still valid [since the
3493 start of the block]. */
3494 reset_opr_set_tables ();
3496 for (insn = bb->head;
3497 insn != NULL && insn != NEXT_INSN (bb->end);
3498 insn = NEXT_INSN (insn))
3500 /* Is insn of form (set (pseudo-reg) ...)? */
3501 if (GET_CODE (insn) == INSN
3502 && GET_CODE (PATTERN (insn)) == SET
3503 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
3504 && REGNO (SET_DEST (PATTERN (insn))) >= FIRST_PSEUDO_REGISTER)
3506 rtx pat = PATTERN (insn);
3507 rtx src = SET_SRC (pat);
3510 if (want_to_gcse_p (src)
3511 /* Is the expression recorded? */
3512 && ((expr = lookup_expr (src, &expr_hash_table)) != NULL)
3513 /* Is the expression available [at the start of the
3515 && TEST_BIT (ae_in[bb->index], expr->bitmap_index)
3516 /* Are the operands unchanged since the start of the
3518 && oprs_not_set_p (src, insn))
3519 changed |= handle_avail_expr (insn, expr);
3522 /* Keep track of everything modified by this insn. */
3523 /* ??? Need to be careful w.r.t. mods done to INSN. */
3525 mark_oprs_set (insn);
3532 /* Top level routine to perform one classic GCSE pass.
3534 Return nonzero if a change was made. */
3537 one_classic_gcse_pass (int pass)
3541 gcse_subst_count = 0;
3542 gcse_create_count = 0;
3544 alloc_hash_table (max_cuid, &expr_hash_table, 0);
3545 alloc_rd_mem (last_basic_block, max_cuid);
3546 compute_hash_table (&expr_hash_table);
3548 dump_hash_table (gcse_file, "Expression", &expr_hash_table);
3550 if (expr_hash_table.n_elems > 0)
3554 alloc_avail_expr_mem (last_basic_block, expr_hash_table.n_elems);
3555 compute_ae_gen (&expr_hash_table);
3556 compute_ae_kill (ae_gen, ae_kill, &expr_hash_table);
3557 compute_available (ae_gen, ae_kill, ae_out, ae_in);
3558 changed = classic_gcse ();
3559 free_avail_expr_mem ();
3563 free_hash_table (&expr_hash_table);
3567 fprintf (gcse_file, "\n");
3568 fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
3569 current_function_name, pass, bytes_used, gcse_subst_count);
3570 fprintf (gcse_file, "%d insns created\n", gcse_create_count);
3576 /* Compute copy/constant propagation working variables. */
3578 /* Local properties of assignments. */
3579 static sbitmap *cprop_pavloc;
3580 static sbitmap *cprop_absaltered;
3582 /* Global properties of assignments (computed from the local properties). */
3583 static sbitmap *cprop_avin;
3584 static sbitmap *cprop_avout;
3586 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
3587 basic blocks. N_SETS is the number of sets. */
3590 alloc_cprop_mem (int n_blocks, int n_sets)
3592 cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
3593 cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
3595 cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
3596 cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
3599 /* Free vars used by copy/const propagation. */
3602 free_cprop_mem (void)
3604 sbitmap_vector_free (cprop_pavloc);
3605 sbitmap_vector_free (cprop_absaltered);
3606 sbitmap_vector_free (cprop_avin);
3607 sbitmap_vector_free (cprop_avout);
3610 /* For each block, compute whether X is transparent. X is either an
3611 expression or an assignment [though we don't care which, for this context
3612 an assignment is treated as an expression]. For each block where an
3613 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
3617 compute_transp (rtx x, int indx, sbitmap *bmap, int set_p)
3625 /* repeat is used to turn tail-recursion into iteration since GCC
3626 can't do it when there's no return value. */
3632 code = GET_CODE (x);
3638 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
3641 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
3642 SET_BIT (bmap[bb->index], indx);
3646 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
3647 SET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
3652 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
3655 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
3656 RESET_BIT (bmap[bb->index], indx);
3660 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
3661 RESET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
3670 rtx list_entry = canon_modify_mem_list[bb->index];
3674 rtx dest, dest_addr;
3676 if (GET_CODE (XEXP (list_entry, 0)) == CALL_INSN)
3679 SET_BIT (bmap[bb->index], indx);
3681 RESET_BIT (bmap[bb->index], indx);
3684 /* LIST_ENTRY must be an INSN of some kind that sets memory.
3685 Examine each hunk of memory that is modified. */
3687 dest = XEXP (list_entry, 0);
3688 list_entry = XEXP (list_entry, 1);
3689 dest_addr = XEXP (list_entry, 0);
3691 if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
3692 x, rtx_addr_varies_p))
3695 SET_BIT (bmap[bb->index], indx);
3697 RESET_BIT (bmap[bb->index], indx);
3700 list_entry = XEXP (list_entry, 1);
3723 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3727 /* If we are about to do the last recursive call
3728 needed at this level, change it into iteration.
3729 This function is called enough to be worth it. */
3736 compute_transp (XEXP (x, i), indx, bmap, set_p);
3738 else if (fmt[i] == 'E')
3739 for (j = 0; j < XVECLEN (x, i); j++)
3740 compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
3744 /* Top level routine to do the dataflow analysis needed by copy/const
3748 compute_cprop_data (void)
3750 compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, &set_hash_table);
3751 compute_available (cprop_pavloc, cprop_absaltered,
3752 cprop_avout, cprop_avin);
3755 /* Copy/constant propagation. */
3757 /* Maximum number of register uses in an insn that we handle. */
3760 /* Table of uses found in an insn.
3761 Allocated statically to avoid alloc/free complexity and overhead. */
3762 static struct reg_use reg_use_table[MAX_USES];
3764 /* Index into `reg_use_table' while building it. */
3765 static int reg_use_count;
3767 /* Set up a list of register numbers used in INSN. The found uses are stored
3768 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
3769 and contains the number of uses in the table upon exit.
3771 ??? If a register appears multiple times we will record it multiple times.
3772 This doesn't hurt anything but it will slow things down. */
3775 find_used_regs (rtx *xptr, void *data ATTRIBUTE_UNUSED)
3782 /* repeat is used to turn tail-recursion into iteration since GCC
3783 can't do it when there's no return value. */
3788 code = GET_CODE (x);
3791 if (reg_use_count == MAX_USES)
3794 reg_use_table[reg_use_count].reg_rtx = x;
3798 /* Recursively scan the operands of this expression. */
3800 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3804 /* If we are about to do the last recursive call
3805 needed at this level, change it into iteration.
3806 This function is called enough to be worth it. */
3813 find_used_regs (&XEXP (x, i), data);
3815 else if (fmt[i] == 'E')
3816 for (j = 0; j < XVECLEN (x, i); j++)
3817 find_used_regs (&XVECEXP (x, i, j), data);
3821 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
3822 Returns nonzero is successful. */
3825 try_replace_reg (rtx from, rtx to, rtx insn)
3827 rtx note = find_reg_equal_equiv_note (insn);
3830 rtx set = single_set (insn);
3832 validate_replace_src_group (from, to, insn);
3833 if (num_changes_pending () && apply_change_group ())
3836 /* Try to simplify SET_SRC if we have substituted a constant. */
3837 if (success && set && CONSTANT_P (to))
3839 src = simplify_rtx (SET_SRC (set));
3842 validate_change (insn, &SET_SRC (set), src, 0);
3845 /* If there is already a NOTE, update the expression in it with our
3848 XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to);
3850 if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
3852 /* If above failed and this is a single set, try to simplify the source of
3853 the set given our substitution. We could perhaps try this for multiple
3854 SETs, but it probably won't buy us anything. */
3855 src = simplify_replace_rtx (SET_SRC (set), from, to);
3857 if (!rtx_equal_p (src, SET_SRC (set))
3858 && validate_change (insn, &SET_SRC (set), src, 0))
3861 /* If we've failed to do replacement, have a single SET, don't already
3862 have a note, and have no special SET, add a REG_EQUAL note to not
3863 lose information. */
3864 if (!success && note == 0 && set != 0
3865 && GET_CODE (XEXP (set, 0)) != ZERO_EXTRACT
3866 && GET_CODE (XEXP (set, 0)) != SIGN_EXTRACT)
3867 note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
3870 /* REG_EQUAL may get simplified into register.
3871 We don't allow that. Remove that note. This code ought
3872 not to happen, because previous code ought to synthesize
3873 reg-reg move, but be on the safe side. */
3874 if (note && REG_P (XEXP (note, 0)))
3875 remove_note (insn, note);
3880 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
3881 NULL no such set is found. */
3883 static struct expr *
3884 find_avail_set (int regno, rtx insn)
3886 /* SET1 contains the last set found that can be returned to the caller for
3887 use in a substitution. */
3888 struct expr *set1 = 0;
3890 /* Loops are not possible here. To get a loop we would need two sets
3891 available at the start of the block containing INSN. ie we would
3892 need two sets like this available at the start of the block:
3894 (set (reg X) (reg Y))
3895 (set (reg Y) (reg X))
3897 This can not happen since the set of (reg Y) would have killed the
3898 set of (reg X) making it unavailable at the start of this block. */
3902 struct expr *set = lookup_set (regno, &set_hash_table);
3904 /* Find a set that is available at the start of the block
3905 which contains INSN. */
3908 if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
3910 set = next_set (regno, set);
3913 /* If no available set was found we've reached the end of the
3914 (possibly empty) copy chain. */
3918 if (GET_CODE (set->expr) != SET)
3921 src = SET_SRC (set->expr);
3923 /* We know the set is available.
3924 Now check that SRC is ANTLOC (i.e. none of the source operands
3925 have changed since the start of the block).
3927 If the source operand changed, we may still use it for the next
3928 iteration of this loop, but we may not use it for substitutions. */
3930 if (gcse_constant_p (src) || oprs_not_set_p (src, insn))
3933 /* If the source of the set is anything except a register, then
3934 we have reached the end of the copy chain. */
3935 if (GET_CODE (src) != REG)
3938 /* Follow the copy chain, ie start another iteration of the loop
3939 and see if we have an available copy into SRC. */
3940 regno = REGNO (src);
3943 /* SET1 holds the last set that was available and anticipatable at
3948 /* Subroutine of cprop_insn that tries to propagate constants into
3949 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
3950 it is the instruction that immediately precedes JUMP, and must be a
3951 single SET of a register. FROM is what we will try to replace,
3952 SRC is the constant we will try to substitute for it. Returns nonzero
3953 if a change was made. */
3956 cprop_jump (basic_block bb, rtx setcc, rtx jump, rtx from, rtx src)
3958 rtx new, set_src, note_src;
3959 rtx set = pc_set (jump);
3960 rtx note = find_reg_equal_equiv_note (jump);
3964 note_src = XEXP (note, 0);
3965 if (GET_CODE (note_src) == EXPR_LIST)
3966 note_src = NULL_RTX;
3968 else note_src = NULL_RTX;
3970 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
3971 set_src = note_src ? note_src : SET_SRC (set);
3973 /* First substitute the SETCC condition into the JUMP instruction,
3974 then substitute that given values into this expanded JUMP. */
3975 if (setcc != NULL_RTX
3976 && !modified_between_p (from, setcc, jump)
3977 && !modified_between_p (src, setcc, jump))
3980 rtx setcc_set = single_set (setcc);
3981 rtx setcc_note = find_reg_equal_equiv_note (setcc);
3982 setcc_src = (setcc_note && GET_CODE (XEXP (setcc_note, 0)) != EXPR_LIST)
3983 ? XEXP (setcc_note, 0) : SET_SRC (setcc_set);
3984 set_src = simplify_replace_rtx (set_src, SET_DEST (setcc_set),
3990 new = simplify_replace_rtx (set_src, from, src);
3992 /* If no simplification can be made, then try the next register. */
3993 if (rtx_equal_p (new, SET_SRC (set)))
3996 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
4001 /* Ensure the value computed inside the jump insn to be equivalent
4002 to one computed by setcc. */
4003 if (setcc && modified_in_p (new, setcc))
4005 if (! validate_change (jump, &SET_SRC (set), new, 0))
4007 /* When (some) constants are not valid in a comparison, and there
4008 are two registers to be replaced by constants before the entire
4009 comparison can be folded into a constant, we need to keep
4010 intermediate information in REG_EQUAL notes. For targets with
4011 separate compare insns, such notes are added by try_replace_reg.
4012 When we have a combined compare-and-branch instruction, however,
4013 we need to attach a note to the branch itself to make this
4014 optimization work. */
4016 if (!rtx_equal_p (new, note_src))
4017 set_unique_reg_note (jump, REG_EQUAL, copy_rtx (new));
4021 /* Remove REG_EQUAL note after simplification. */
4023 remove_note (jump, note);
4025 /* If this has turned into an unconditional jump,
4026 then put a barrier after it so that the unreachable
4027 code will be deleted. */
4028 if (GET_CODE (SET_SRC (set)) == LABEL_REF)
4029 emit_barrier_after (jump);
4033 /* Delete the cc0 setter. */
4034 if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
4035 delete_insn (setcc);
4038 run_jump_opt_after_gcse = 1;
4041 if (gcse_file != NULL)
4044 "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
4045 REGNO (from), INSN_UID (jump));
4046 print_rtl (gcse_file, src);
4047 fprintf (gcse_file, "\n");
4049 purge_dead_edges (bb);
4055 constprop_register (rtx insn, rtx from, rtx to, int alter_jumps)
4059 /* Check for reg or cc0 setting instructions followed by
4060 conditional branch instructions first. */
4062 && (sset = single_set (insn)) != NULL
4064 && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
4066 rtx dest = SET_DEST (sset);
4067 if ((REG_P (dest) || CC0_P (dest))
4068 && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to))
4072 /* Handle normal insns next. */
4073 if (GET_CODE (insn) == INSN
4074 && try_replace_reg (from, to, insn))
4077 /* Try to propagate a CONST_INT into a conditional jump.
4078 We're pretty specific about what we will handle in this
4079 code, we can extend this as necessary over time.
4081 Right now the insn in question must look like
4082 (set (pc) (if_then_else ...)) */
4083 else if (alter_jumps && any_condjump_p (insn) && onlyjump_p (insn))
4084 return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to);
4088 /* Perform constant and copy propagation on INSN.
4089 The result is nonzero if a change was made. */
4092 cprop_insn (rtx insn, int alter_jumps)
4094 struct reg_use *reg_used;
4102 note_uses (&PATTERN (insn), find_used_regs, NULL);
4104 note = find_reg_equal_equiv_note (insn);
4106 /* We may win even when propagating constants into notes. */
4108 find_used_regs (&XEXP (note, 0), NULL);
4110 for (reg_used = ®_use_table[0]; reg_use_count > 0;
4111 reg_used++, reg_use_count--)
4113 unsigned int regno = REGNO (reg_used->reg_rtx);
4117 /* Ignore registers created by GCSE.
4118 We do this because ... */
4119 if (regno >= max_gcse_regno)
4122 /* If the register has already been set in this block, there's
4123 nothing we can do. */
4124 if (! oprs_not_set_p (reg_used->reg_rtx, insn))
4127 /* Find an assignment that sets reg_used and is available
4128 at the start of the block. */
4129 set = find_avail_set (regno, insn);
4134 /* ??? We might be able to handle PARALLELs. Later. */
4135 if (GET_CODE (pat) != SET)
4138 src = SET_SRC (pat);
4140 /* Constant propagation. */
4141 if (gcse_constant_p (src))
4143 if (constprop_register (insn, reg_used->reg_rtx, src, alter_jumps))
4147 if (gcse_file != NULL)
4149 fprintf (gcse_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
4150 fprintf (gcse_file, "insn %d with constant ", INSN_UID (insn));
4151 print_rtl (gcse_file, src);
4152 fprintf (gcse_file, "\n");
4154 if (INSN_DELETED_P (insn))
4158 else if (GET_CODE (src) == REG
4159 && REGNO (src) >= FIRST_PSEUDO_REGISTER
4160 && REGNO (src) != regno)
4162 if (try_replace_reg (reg_used->reg_rtx, src, insn))
4166 if (gcse_file != NULL)
4168 fprintf (gcse_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
4169 regno, INSN_UID (insn));
4170 fprintf (gcse_file, " with reg %d\n", REGNO (src));
4173 /* The original insn setting reg_used may or may not now be
4174 deletable. We leave the deletion to flow. */
4175 /* FIXME: If it turns out that the insn isn't deletable,
4176 then we may have unnecessarily extended register lifetimes
4177 and made things worse. */
4185 /* Like find_used_regs, but avoid recording uses that appear in
4186 input-output contexts such as zero_extract or pre_dec. This
4187 restricts the cases we consider to those for which local cprop
4188 can legitimately make replacements. */
4191 local_cprop_find_used_regs (rtx *xptr, void *data)
4198 switch (GET_CODE (x))
4202 case STRICT_LOW_PART:
4211 /* Can only legitimately appear this early in the context of
4212 stack pushes for function arguments, but handle all of the
4213 codes nonetheless. */
4217 /* Setting a subreg of a register larger than word_mode leaves
4218 the non-written words unchanged. */
4219 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
4227 find_used_regs (xptr, data);
4230 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4231 their REG_EQUAL notes need updating. */
4234 do_local_cprop (rtx x, rtx insn, int alter_jumps, rtx *libcall_sp)
4236 rtx newreg = NULL, newcnst = NULL;
4238 /* Rule out USE instructions and ASM statements as we don't want to
4239 change the hard registers mentioned. */
4240 if (GET_CODE (x) == REG
4241 && (REGNO (x) >= FIRST_PSEUDO_REGISTER
4242 || (GET_CODE (PATTERN (insn)) != USE
4243 && asm_noperands (PATTERN (insn)) < 0)))
4245 cselib_val *val = cselib_lookup (x, GET_MODE (x), 0);
4246 struct elt_loc_list *l;
4250 for (l = val->locs; l; l = l->next)
4252 rtx this_rtx = l->loc;
4258 if (gcse_constant_p (this_rtx))
4260 if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
4261 /* Don't copy propagate if it has attached REG_EQUIV note.
4262 At this point this only function parameters should have
4263 REG_EQUIV notes and if the argument slot is used somewhere
4264 explicitly, it means address of parameter has been taken,
4265 so we should not extend the lifetime of the pseudo. */
4266 && (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX))
4267 || GET_CODE (XEXP (note, 0)) != MEM))
4270 if (newcnst && constprop_register (insn, x, newcnst, alter_jumps))
4272 /* If we find a case where we can't fix the retval REG_EQUAL notes
4273 match the new register, we either have to abandon this replacement
4274 or fix delete_trivially_dead_insns to preserve the setting insn,
4275 or make it delete the REG_EUAQL note, and fix up all passes that
4276 require the REG_EQUAL note there. */
4277 if (!adjust_libcall_notes (x, newcnst, insn, libcall_sp))
4279 if (gcse_file != NULL)
4281 fprintf (gcse_file, "LOCAL CONST-PROP: Replacing reg %d in ",
4283 fprintf (gcse_file, "insn %d with constant ",
4285 print_rtl (gcse_file, newcnst);
4286 fprintf (gcse_file, "\n");
4291 else if (newreg && newreg != x && try_replace_reg (x, newreg, insn))
4293 adjust_libcall_notes (x, newreg, insn, libcall_sp);
4294 if (gcse_file != NULL)
4297 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
4298 REGNO (x), INSN_UID (insn));
4299 fprintf (gcse_file, " with reg %d\n", REGNO (newreg));
4308 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4309 their REG_EQUAL notes need updating to reflect that OLDREG has been
4310 replaced with NEWVAL in INSN. Return true if all substitutions could
4313 adjust_libcall_notes (rtx oldreg, rtx newval, rtx insn, rtx *libcall_sp)
4317 while ((end = *libcall_sp++))
4319 rtx note = find_reg_equal_equiv_note (end);
4326 if (reg_set_between_p (newval, PREV_INSN (insn), end))
4330 note = find_reg_equal_equiv_note (end);
4333 if (reg_mentioned_p (newval, XEXP (note, 0)))
4336 while ((end = *libcall_sp++));
4340 XEXP (note, 0) = replace_rtx (XEXP (note, 0), oldreg, newval);
4346 #define MAX_NESTED_LIBCALLS 9
4349 local_cprop_pass (int alter_jumps)
4352 struct reg_use *reg_used;
4353 rtx libcall_stack[MAX_NESTED_LIBCALLS + 1], *libcall_sp;
4354 bool changed = false;
4357 libcall_sp = &libcall_stack[MAX_NESTED_LIBCALLS];
4359 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4363 rtx note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
4367 if (libcall_sp == libcall_stack)
4369 *--libcall_sp = XEXP (note, 0);
4371 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
4374 note = find_reg_equal_equiv_note (insn);
4378 note_uses (&PATTERN (insn), local_cprop_find_used_regs, NULL);
4380 local_cprop_find_used_regs (&XEXP (note, 0), NULL);
4382 for (reg_used = ®_use_table[0]; reg_use_count > 0;
4383 reg_used++, reg_use_count--)
4384 if (do_local_cprop (reg_used->reg_rtx, insn, alter_jumps,
4390 if (INSN_DELETED_P (insn))
4393 while (reg_use_count);
4395 cselib_process_insn (insn);
4398 /* Global analysis may get into infinite loops for unreachable blocks. */
4399 if (changed && alter_jumps)
4401 delete_unreachable_blocks ();
4402 free_reg_set_mem ();
4403 alloc_reg_set_mem (max_reg_num ());
4404 compute_sets (get_insns ());
4408 /* Forward propagate copies. This includes copies and constants. Return
4409 nonzero if a change was made. */
4412 cprop (int alter_jumps)
4418 /* Note we start at block 1. */
4419 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
4421 if (gcse_file != NULL)
4422 fprintf (gcse_file, "\n");
4427 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
4429 /* Reset tables used to keep track of what's still valid [since the
4430 start of the block]. */
4431 reset_opr_set_tables ();
4433 for (insn = bb->head;
4434 insn != NULL && insn != NEXT_INSN (bb->end);
4435 insn = NEXT_INSN (insn))
4438 changed |= cprop_insn (insn, alter_jumps);
4440 /* Keep track of everything modified by this insn. */
4441 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
4442 call mark_oprs_set if we turned the insn into a NOTE. */
4443 if (GET_CODE (insn) != NOTE)
4444 mark_oprs_set (insn);
4448 if (gcse_file != NULL)
4449 fprintf (gcse_file, "\n");
4454 /* Similar to get_condition, only the resulting condition must be
4455 valid at JUMP, instead of at EARLIEST.
4457 This differs from noce_get_condition in ifcvt.c in that we prefer not to
4458 settle for the condition variable in the jump instruction being integral.
4459 We prefer to be able to record the value of a user variable, rather than
4460 the value of a temporary used in a condition. This could be solved by
4461 recording the value of *every* register scaned by canonicalize_condition,
4462 but this would require some code reorganization. */
4465 fis_get_condition (rtx jump)
4467 rtx cond, set, tmp, insn, earliest;
4470 if (! any_condjump_p (jump))
4473 set = pc_set (jump);
4474 cond = XEXP (SET_SRC (set), 0);
4476 /* If this branches to JUMP_LABEL when the condition is false,
4477 reverse the condition. */
4478 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
4479 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
4481 /* Use canonicalize_condition to do the dirty work of manipulating
4482 MODE_CC values and COMPARE rtx codes. */
4483 tmp = canonicalize_condition (jump, cond, reverse, &earliest, NULL_RTX,
4488 /* Verify that the given condition is valid at JUMP by virtue of not
4489 having been modified since EARLIEST. */
4490 for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
4491 if (INSN_P (insn) && modified_in_p (tmp, insn))
4496 /* The condition was modified. See if we can get a partial result
4497 that doesn't follow all the reversals. Perhaps combine can fold
4498 them together later. */
4499 tmp = XEXP (tmp, 0);
4500 if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
4502 tmp = canonicalize_condition (jump, cond, reverse, &earliest, tmp,
4507 /* For sanity's sake, re-validate the new result. */
4508 for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
4509 if (INSN_P (insn) && modified_in_p (tmp, insn))
4515 /* Find the implicit sets of a function. An "implicit set" is a constraint
4516 on the value of a variable, implied by a conditional jump. For example,
4517 following "if (x == 2)", the then branch may be optimized as though the
4518 conditional performed an "explicit set", in this example, "x = 2". This
4519 function records the set patterns that are implicit at the start of each
4523 find_implicit_sets (void)
4525 basic_block bb, dest;
4531 /* Check for more than one successor. */
4532 if (bb->succ && bb->succ->succ_next)
4534 cond = fis_get_condition (bb->end);
4537 && (GET_CODE (cond) == EQ || GET_CODE (cond) == NE)
4538 && GET_CODE (XEXP (cond, 0)) == REG
4539 && REGNO (XEXP (cond, 0)) >= FIRST_PSEUDO_REGISTER
4540 && gcse_constant_p (XEXP (cond, 1)))
4542 dest = GET_CODE (cond) == EQ ? BRANCH_EDGE (bb)->dest
4543 : FALLTHRU_EDGE (bb)->dest;
4545 if (dest && ! dest->pred->pred_next
4546 && dest != EXIT_BLOCK_PTR)
4548 new = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
4550 implicit_sets[dest->index] = new;
4553 fprintf(gcse_file, "Implicit set of reg %d in ",
4554 REGNO (XEXP (cond, 0)));
4555 fprintf(gcse_file, "basic block %d\n", dest->index);
4563 fprintf (gcse_file, "Found %d implicit sets\n", count);
4566 /* Perform one copy/constant propagation pass.
4567 PASS is the pass count. If CPROP_JUMPS is true, perform constant
4568 propagation into conditional jumps. If BYPASS_JUMPS is true,
4569 perform conditional jump bypassing optimizations. */
4572 one_cprop_pass (int pass, int cprop_jumps, int bypass_jumps)
4576 const_prop_count = 0;
4577 copy_prop_count = 0;
4579 local_cprop_pass (cprop_jumps);
4581 /* Determine implicit sets. */
4582 implicit_sets = xcalloc (last_basic_block, sizeof (rtx));
4583 find_implicit_sets ();
4585 alloc_hash_table (max_cuid, &set_hash_table, 1);
4586 compute_hash_table (&set_hash_table);
4588 /* Free implicit_sets before peak usage. */
4589 free (implicit_sets);
4590 implicit_sets = NULL;
4593 dump_hash_table (gcse_file, "SET", &set_hash_table);
4594 if (set_hash_table.n_elems > 0)
4596 alloc_cprop_mem (last_basic_block, set_hash_table.n_elems);
4597 compute_cprop_data ();
4598 changed = cprop (cprop_jumps);
4600 changed |= bypass_conditional_jumps ();
4604 free_hash_table (&set_hash_table);
4608 fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, ",
4609 current_function_name, pass, bytes_used);
4610 fprintf (gcse_file, "%d const props, %d copy props\n\n",
4611 const_prop_count, copy_prop_count);
4613 /* Global analysis may get into infinite loops for unreachable blocks. */
4614 if (changed && cprop_jumps)
4615 delete_unreachable_blocks ();
4620 /* Bypass conditional jumps. */
4622 /* The value of last_basic_block at the beginning of the jump_bypass
4623 pass. The use of redirect_edge_and_branch_force may introduce new
4624 basic blocks, but the data flow analysis is only valid for basic
4625 block indices less than bypass_last_basic_block. */
4627 static int bypass_last_basic_block;
4629 /* Find a set of REGNO to a constant that is available at the end of basic
4630 block BB. Returns NULL if no such set is found. Based heavily upon
4633 static struct expr *
4634 find_bypass_set (int regno, int bb)
4636 struct expr *result = 0;
4641 struct expr *set = lookup_set (regno, &set_hash_table);
4645 if (TEST_BIT (cprop_avout[bb], set->bitmap_index))
4647 set = next_set (regno, set);
4653 if (GET_CODE (set->expr) != SET)
4656 src = SET_SRC (set->expr);
4657 if (gcse_constant_p (src))
4660 if (GET_CODE (src) != REG)
4663 regno = REGNO (src);
4669 /* Subroutine of bypass_block that checks whether a pseudo is killed by
4670 any of the instructions inserted on an edge. Jump bypassing places
4671 condition code setters on CFG edges using insert_insn_on_edge. This
4672 function is required to check that our data flow analysis is still
4673 valid prior to commit_edge_insertions. */
4676 reg_killed_on_edge (rtx reg, edge e)
4680 for (insn = e->insns; insn; insn = NEXT_INSN (insn))
4681 if (INSN_P (insn) && reg_set_p (reg, insn))
4687 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
4688 basic block BB which has more than one predecessor. If not NULL, SETCC
4689 is the first instruction of BB, which is immediately followed by JUMP_INSN
4690 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
4691 Returns nonzero if a change was made.
4693 During the jump bypassing pass, we may place copies of SETCC instructions
4694 on CFG edges. The following routine must be careful to pay attention to
4695 these inserted insns when performing its transformations. */
4698 bypass_block (basic_block bb, rtx setcc, rtx jump)
4701 edge e, enext, edest;
4703 int may_be_loop_header;
4705 insn = (setcc != NULL) ? setcc : jump;
4707 /* Determine set of register uses in INSN. */
4709 note_uses (&PATTERN (insn), find_used_regs, NULL);
4710 note = find_reg_equal_equiv_note (insn);
4712 find_used_regs (&XEXP (note, 0), NULL);
4714 may_be_loop_header = false;
4715 for (e = bb->pred; e; e = e->pred_next)
4716 if (e->flags & EDGE_DFS_BACK)
4718 may_be_loop_header = true;
4723 for (e = bb->pred; e; e = enext)
4725 enext = e->pred_next;
4726 if (e->flags & EDGE_COMPLEX)
4729 /* We can't redirect edges from new basic blocks. */
4730 if (e->src->index >= bypass_last_basic_block)
4733 /* The irreducible loops created by redirecting of edges entering the
4734 loop from outside would decrease effectiveness of some of the following
4735 optimizations, so prevent this. */
4736 if (may_be_loop_header
4737 && !(e->flags & EDGE_DFS_BACK))
4740 for (i = 0; i < reg_use_count; i++)
4742 struct reg_use *reg_used = ®_use_table[i];
4743 unsigned int regno = REGNO (reg_used->reg_rtx);
4744 basic_block dest, old_dest;
4748 if (regno >= max_gcse_regno)
4751 set = find_bypass_set (regno, e->src->index);
4756 /* Check the data flow is valid after edge insertions. */
4757 if (e->insns && reg_killed_on_edge (reg_used->reg_rtx, e))
4760 src = SET_SRC (pc_set (jump));
4763 src = simplify_replace_rtx (src,
4764 SET_DEST (PATTERN (setcc)),
4765 SET_SRC (PATTERN (setcc)));
4767 new = simplify_replace_rtx (src, reg_used->reg_rtx,
4768 SET_SRC (set->expr));
4770 /* Jump bypassing may have already placed instructions on
4771 edges of the CFG. We can't bypass an outgoing edge that
4772 has instructions associated with it, as these insns won't
4773 get executed if the incoming edge is redirected. */
4777 edest = FALLTHRU_EDGE (bb);
4778 dest = edest->insns ? NULL : edest->dest;
4780 else if (GET_CODE (new) == LABEL_REF)
4782 dest = BLOCK_FOR_INSN (XEXP (new, 0));
4783 /* Don't bypass edges containing instructions. */
4784 for (edest = bb->succ; edest; edest = edest->succ_next)
4785 if (edest->dest == dest && edest->insns)
4797 && dest != EXIT_BLOCK_PTR)
4799 redirect_edge_and_branch_force (e, dest);
4801 /* Copy the register setter to the redirected edge.
4802 Don't copy CC0 setters, as CC0 is dead after jump. */
4805 rtx pat = PATTERN (setcc);
4806 if (!CC0_P (SET_DEST (pat)))
4807 insert_insn_on_edge (copy_insn (pat), e);
4810 if (gcse_file != NULL)
4812 fprintf (gcse_file, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
4813 regno, INSN_UID (jump));
4814 print_rtl (gcse_file, SET_SRC (set->expr));
4815 fprintf (gcse_file, "\nBypass edge from %d->%d to %d\n",
4816 e->src->index, old_dest->index, dest->index);
4826 /* Find basic blocks with more than one predecessor that only contain a
4827 single conditional jump. If the result of the comparison is known at
4828 compile-time from any incoming edge, redirect that edge to the
4829 appropriate target. Returns nonzero if a change was made.
4831 This function is now mis-named, because we also handle indirect jumps. */
4834 bypass_conditional_jumps (void)
4842 /* Note we start at block 1. */
4843 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
4846 bypass_last_basic_block = last_basic_block;
4847 mark_dfs_back_edges ();
4850 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb,
4851 EXIT_BLOCK_PTR, next_bb)
4853 /* Check for more than one predecessor. */
4854 if (bb->pred && bb->pred->pred_next)
4857 for (insn = bb->head;
4858 insn != NULL && insn != NEXT_INSN (bb->end);
4859 insn = NEXT_INSN (insn))
4860 if (GET_CODE (insn) == INSN)
4864 if (GET_CODE (PATTERN (insn)) != SET)
4867 dest = SET_DEST (PATTERN (insn));
4868 if (REG_P (dest) || CC0_P (dest))
4873 else if (GET_CODE (insn) == JUMP_INSN)
4875 if ((any_condjump_p (insn) || computed_jump_p (insn))
4876 && onlyjump_p (insn))
4877 changed |= bypass_block (bb, setcc, insn);
4880 else if (INSN_P (insn))
4885 /* If we bypassed any register setting insns, we inserted a
4886 copy on the redirected edge. These need to be committed. */
4888 commit_edge_insertions();
4893 /* Compute PRE+LCM working variables. */
4895 /* Local properties of expressions. */
4896 /* Nonzero for expressions that are transparent in the block. */
4897 static sbitmap *transp;
4899 /* Nonzero for expressions that are transparent at the end of the block.
4900 This is only zero for expressions killed by abnormal critical edge
4901 created by a calls. */
4902 static sbitmap *transpout;
4904 /* Nonzero for expressions that are computed (available) in the block. */
4905 static sbitmap *comp;
4907 /* Nonzero for expressions that are locally anticipatable in the block. */
4908 static sbitmap *antloc;
4910 /* Nonzero for expressions where this block is an optimal computation
4912 static sbitmap *pre_optimal;
4914 /* Nonzero for expressions which are redundant in a particular block. */
4915 static sbitmap *pre_redundant;
4917 /* Nonzero for expressions which should be inserted on a specific edge. */
4918 static sbitmap *pre_insert_map;
4920 /* Nonzero for expressions which should be deleted in a specific block. */
4921 static sbitmap *pre_delete_map;
4923 /* Contains the edge_list returned by pre_edge_lcm. */
4924 static struct edge_list *edge_list;
4926 /* Redundant insns. */
4927 static sbitmap pre_redundant_insns;
4929 /* Allocate vars used for PRE analysis. */
4932 alloc_pre_mem (int n_blocks, int n_exprs)
4934 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
4935 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
4936 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
4939 pre_redundant = NULL;
4940 pre_insert_map = NULL;
4941 pre_delete_map = NULL;
4944 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
4946 /* pre_insert and pre_delete are allocated later. */
4949 /* Free vars used for PRE analysis. */
4954 sbitmap_vector_free (transp);
4955 sbitmap_vector_free (comp);
4957 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
4960 sbitmap_vector_free (pre_optimal);
4962 sbitmap_vector_free (pre_redundant);
4964 sbitmap_vector_free (pre_insert_map);
4966 sbitmap_vector_free (pre_delete_map);
4968 sbitmap_vector_free (ae_in);
4970 sbitmap_vector_free (ae_out);
4972 transp = comp = NULL;
4973 pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
4974 ae_in = ae_out = NULL;
4977 /* Top level routine to do the dataflow analysis needed by PRE. */
4980 compute_pre_data (void)
4982 sbitmap trapping_expr;
4986 compute_local_properties (transp, comp, antloc, &expr_hash_table);
4987 sbitmap_vector_zero (ae_kill, last_basic_block);
4989 /* Collect expressions which might trap. */
4990 trapping_expr = sbitmap_alloc (expr_hash_table.n_elems);
4991 sbitmap_zero (trapping_expr);
4992 for (ui = 0; ui < expr_hash_table.size; ui++)
4995 for (e = expr_hash_table.table[ui]; e != NULL; e = e->next_same_hash)
4996 if (may_trap_p (e->expr))
4997 SET_BIT (trapping_expr, e->bitmap_index);
5000 /* Compute ae_kill for each basic block using:
5004 This is significantly faster than compute_ae_kill. */
5010 /* If the current block is the destination of an abnormal edge, we
5011 kill all trapping expressions because we won't be able to properly
5012 place the instruction on the edge. So make them neither
5013 anticipatable nor transparent. This is fairly conservative. */
5014 for (e = bb->pred; e ; e = e->pred_next)
5015 if (e->flags & EDGE_ABNORMAL)
5017 sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr);
5018 sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr);
5022 sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]);
5023 sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]);
5026 edge_list = pre_edge_lcm (gcse_file, expr_hash_table.n_elems, transp, comp, antloc,
5027 ae_kill, &pre_insert_map, &pre_delete_map);
5028 sbitmap_vector_free (antloc);
5030 sbitmap_vector_free (ae_kill);
5032 sbitmap_free (trapping_expr);
5037 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
5040 VISITED is a pointer to a working buffer for tracking which BB's have
5041 been visited. It is NULL for the top-level call.
5043 We treat reaching expressions that go through blocks containing the same
5044 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
5045 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
5046 2 as not reaching. The intent is to improve the probability of finding
5047 only one reaching expression and to reduce register lifetimes by picking
5048 the closest such expression. */
5051 pre_expr_reaches_here_p_work (basic_block occr_bb, struct expr *expr, basic_block bb, char *visited)
5055 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
5057 basic_block pred_bb = pred->src;
5059 if (pred->src == ENTRY_BLOCK_PTR
5060 /* Has predecessor has already been visited? */
5061 || visited[pred_bb->index])
5062 ;/* Nothing to do. */
5064 /* Does this predecessor generate this expression? */
5065 else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
5067 /* Is this the occurrence we're looking for?
5068 Note that there's only one generating occurrence per block
5069 so we just need to check the block number. */
5070 if (occr_bb == pred_bb)
5073 visited[pred_bb->index] = 1;
5075 /* Ignore this predecessor if it kills the expression. */
5076 else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
5077 visited[pred_bb->index] = 1;
5079 /* Neither gen nor kill. */
5082 visited[pred_bb->index] = 1;
5083 if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
5088 /* All paths have been checked. */
5092 /* The wrapper for pre_expr_reaches_here_work that ensures that any
5093 memory allocated for that function is returned. */
5096 pre_expr_reaches_here_p (basic_block occr_bb, struct expr *expr, basic_block bb)
5099 char *visited = xcalloc (last_basic_block, 1);
5101 rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited);
5108 /* Given an expr, generate RTL which we can insert at the end of a BB,
5109 or on an edge. Set the block number of any insns generated to
5113 process_insert_insn (struct expr *expr)
5115 rtx reg = expr->reaching_reg;
5116 rtx exp = copy_rtx (expr->expr);
5121 /* If the expression is something that's an operand, like a constant,
5122 just copy it to a register. */
5123 if (general_operand (exp, GET_MODE (reg)))
5124 emit_move_insn (reg, exp);
5126 /* Otherwise, make a new insn to compute this expression and make sure the
5127 insn will be recognized (this also adds any needed CLOBBERs). Copy the
5128 expression to make sure we don't have any sharing issues. */
5129 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode, reg, exp))))
5138 /* Add EXPR to the end of basic block BB.
5140 This is used by both the PRE and code hoisting.
5142 For PRE, we want to verify that the expr is either transparent
5143 or locally anticipatable in the target block. This check makes
5144 no sense for code hoisting. */
5147 insert_insn_end_bb (struct expr *expr, basic_block bb, int pre)
5151 rtx reg = expr->reaching_reg;
5152 int regno = REGNO (reg);
5155 pat = process_insert_insn (expr);
5156 if (pat == NULL_RTX || ! INSN_P (pat))
5160 while (NEXT_INSN (pat_end) != NULL_RTX)
5161 pat_end = NEXT_INSN (pat_end);
5163 /* If the last insn is a jump, insert EXPR in front [taking care to
5164 handle cc0, etc. properly]. Similarly we need to care trapping
5165 instructions in presence of non-call exceptions. */
5167 if (GET_CODE (insn) == JUMP_INSN
5168 || (GET_CODE (insn) == INSN
5169 && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL))))
5174 /* It should always be the case that we can put these instructions
5175 anywhere in the basic block with performing PRE optimizations.
5177 if (GET_CODE (insn) == INSN && pre
5178 && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
5179 && !TEST_BIT (transp[bb->index], expr->bitmap_index))
5182 /* If this is a jump table, then we can't insert stuff here. Since
5183 we know the previous real insn must be the tablejump, we insert
5184 the new instruction just before the tablejump. */
5185 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
5186 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
5187 insn = prev_real_insn (insn);
5190 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
5191 if cc0 isn't set. */
5192 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
5194 insn = XEXP (note, 0);
5197 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
5198 if (maybe_cc0_setter
5199 && INSN_P (maybe_cc0_setter)
5200 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
5201 insn = maybe_cc0_setter;
5204 /* FIXME: What if something in cc0/jump uses value set in new insn? */
5205 new_insn = emit_insn_before (pat, insn);
5208 /* Likewise if the last insn is a call, as will happen in the presence
5209 of exception handling. */
5210 else if (GET_CODE (insn) == CALL_INSN
5211 && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL)))
5213 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
5214 we search backward and place the instructions before the first
5215 parameter is loaded. Do this for everyone for consistency and a
5216 presumption that we'll get better code elsewhere as well.
5218 It should always be the case that we can put these instructions
5219 anywhere in the basic block with performing PRE optimizations.
5223 && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
5224 && !TEST_BIT (transp[bb->index], expr->bitmap_index))
5227 /* Since different machines initialize their parameter registers
5228 in different orders, assume nothing. Collect the set of all
5229 parameter registers. */
5230 insn = find_first_parameter_load (insn, bb->head);
5232 /* If we found all the parameter loads, then we want to insert
5233 before the first parameter load.
5235 If we did not find all the parameter loads, then we might have
5236 stopped on the head of the block, which could be a CODE_LABEL.
5237 If we inserted before the CODE_LABEL, then we would be putting
5238 the insn in the wrong basic block. In that case, put the insn
5239 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
5240 while (GET_CODE (insn) == CODE_LABEL
5241 || NOTE_INSN_BASIC_BLOCK_P (insn))
5242 insn = NEXT_INSN (insn);
5244 new_insn = emit_insn_before (pat, insn);
5247 new_insn = emit_insn_after (pat, insn);
5253 add_label_notes (PATTERN (pat), new_insn);
5254 note_stores (PATTERN (pat), record_set_info, pat);
5258 pat = NEXT_INSN (pat);
5261 gcse_create_count++;
5265 fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, ",
5266 bb->index, INSN_UID (new_insn));
5267 fprintf (gcse_file, "copying expression %d to reg %d\n",
5268 expr->bitmap_index, regno);
5272 /* Insert partially redundant expressions on edges in the CFG to make
5273 the expressions fully redundant. */
5276 pre_edge_insert (struct edge_list *edge_list, struct expr **index_map)
5278 int e, i, j, num_edges, set_size, did_insert = 0;
5281 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
5282 if it reaches any of the deleted expressions. */
5284 set_size = pre_insert_map[0]->size;
5285 num_edges = NUM_EDGES (edge_list);
5286 inserted = sbitmap_vector_alloc (num_edges, expr_hash_table.n_elems);
5287 sbitmap_vector_zero (inserted, num_edges);
5289 for (e = 0; e < num_edges; e++)
5292 basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
5294 for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
5296 SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
5298 for (j = indx; insert && j < (int) expr_hash_table.n_elems; j++, insert >>= 1)
5299 if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
5301 struct expr *expr = index_map[j];
5304 /* Now look at each deleted occurrence of this expression. */
5305 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5307 if (! occr->deleted_p)
5310 /* Insert this expression on this edge if if it would
5311 reach the deleted occurrence in BB. */
5312 if (!TEST_BIT (inserted[e], j))
5315 edge eg = INDEX_EDGE (edge_list, e);
5317 /* We can't insert anything on an abnormal and
5318 critical edge, so we insert the insn at the end of
5319 the previous block. There are several alternatives
5320 detailed in Morgans book P277 (sec 10.5) for
5321 handling this situation. This one is easiest for
5324 if ((eg->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
5325 insert_insn_end_bb (index_map[j], bb, 0);
5328 insn = process_insert_insn (index_map[j]);
5329 insert_insn_on_edge (insn, eg);
5334 fprintf (gcse_file, "PRE/HOIST: edge (%d,%d), ",
5336 INDEX_EDGE_SUCC_BB (edge_list, e)->index);
5337 fprintf (gcse_file, "copy expression %d\n",
5338 expr->bitmap_index);
5341 update_ld_motion_stores (expr);
5342 SET_BIT (inserted[e], j);
5344 gcse_create_count++;
5351 sbitmap_vector_free (inserted);
5355 /* Copy the result of INSN to REG. INDX is the expression number.
5356 Given "old_reg <- expr" (INSN), instead of adding after it
5357 reaching_reg <- old_reg
5358 it's better to do the following:
5359 reaching_reg <- expr
5360 old_reg <- reaching_reg
5361 because this way copy propagation can discover additional PRE
5365 pre_insert_copy_insn (struct expr *expr, rtx insn)
5367 rtx reg = expr->reaching_reg;
5368 int regno = REGNO (reg);
5369 int indx = expr->bitmap_index;
5370 rtx set = single_set (insn);
5378 old_reg = SET_DEST (set);
5379 new_insn = emit_insn_after (gen_move_insn (old_reg,
5382 new_set = single_set (new_insn);
5386 SET_DEST (set) = reg;
5388 /* Keep register set table up to date. */
5389 replace_one_set (REGNO (old_reg), insn, new_insn);
5390 record_one_set (regno, insn);
5392 gcse_create_count++;
5396 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
5397 BLOCK_NUM (insn), INSN_UID (new_insn), indx,
5398 INSN_UID (insn), regno);
5399 update_ld_motion_stores (expr);
5402 /* Copy available expressions that reach the redundant expression
5403 to `reaching_reg'. */
5406 pre_insert_copies (void)
5413 /* For each available expression in the table, copy the result to
5414 `reaching_reg' if the expression reaches a deleted one.
5416 ??? The current algorithm is rather brute force.
5417 Need to do some profiling. */
5419 for (i = 0; i < expr_hash_table.size; i++)
5420 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
5422 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
5423 we don't want to insert a copy here because the expression may not
5424 really be redundant. So only insert an insn if the expression was
5425 deleted. This test also avoids further processing if the
5426 expression wasn't deleted anywhere. */
5427 if (expr->reaching_reg == NULL)
5430 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5432 if (! occr->deleted_p)
5435 for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
5437 rtx insn = avail->insn;
5439 /* No need to handle this one if handled already. */
5440 if (avail->copied_p)
5443 /* Don't handle this one if it's a redundant one. */
5444 if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
5447 /* Or if the expression doesn't reach the deleted one. */
5448 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
5450 BLOCK_FOR_INSN (occr->insn)))
5453 /* Copy the result of avail to reaching_reg. */
5454 pre_insert_copy_insn (expr, insn);
5455 avail->copied_p = 1;
5461 /* Emit move from SRC to DEST noting the equivalence with expression computed
5464 gcse_emit_move_after (rtx src, rtx dest, rtx insn)
5467 rtx set = single_set (insn), set2;
5471 /* This should never fail since we're creating a reg->reg copy
5472 we've verified to be valid. */
5474 new = emit_insn_after (gen_move_insn (dest, src), insn);
5476 /* Note the equivalence for local CSE pass. */
5477 set2 = single_set (new);
5478 if (!set2 || !rtx_equal_p (SET_DEST (set2), dest))
5480 if ((note = find_reg_equal_equiv_note (insn)))
5481 eqv = XEXP (note, 0);
5483 eqv = SET_SRC (set);
5485 set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (eqv));
5490 /* Delete redundant computations.
5491 Deletion is done by changing the insn to copy the `reaching_reg' of
5492 the expression into the result of the SET. It is left to later passes
5493 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
5495 Returns nonzero if a change is made. */
5506 for (i = 0; i < expr_hash_table.size; i++)
5507 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
5509 int indx = expr->bitmap_index;
5511 /* We only need to search antic_occr since we require
5514 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5516 rtx insn = occr->insn;
5518 basic_block bb = BLOCK_FOR_INSN (insn);
5520 if (TEST_BIT (pre_delete_map[bb->index], indx))
5522 set = single_set (insn);
5526 /* Create a pseudo-reg to store the result of reaching
5527 expressions into. Get the mode for the new pseudo from
5528 the mode of the original destination pseudo. */
5529 if (expr->reaching_reg == NULL)
5531 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
5533 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
5535 occr->deleted_p = 1;
5536 SET_BIT (pre_redundant_insns, INSN_CUID (insn));
5543 "PRE: redundant insn %d (expression %d) in ",
5544 INSN_UID (insn), indx);
5545 fprintf (gcse_file, "bb %d, reaching reg is %d\n",
5546 bb->index, REGNO (expr->reaching_reg));
5555 /* Perform GCSE optimizations using PRE.
5556 This is called by one_pre_gcse_pass after all the dataflow analysis
5559 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
5560 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
5561 Compiler Design and Implementation.
5563 ??? A new pseudo reg is created to hold the reaching expression. The nice
5564 thing about the classical approach is that it would try to use an existing
5565 reg. If the register can't be adequately optimized [i.e. we introduce
5566 reload problems], one could add a pass here to propagate the new register
5569 ??? We don't handle single sets in PARALLELs because we're [currently] not
5570 able to copy the rest of the parallel when we insert copies to create full
5571 redundancies from partial redundancies. However, there's no reason why we
5572 can't handle PARALLELs in the cases where there are no partial
5579 int did_insert, changed;
5580 struct expr **index_map;
5583 /* Compute a mapping from expression number (`bitmap_index') to
5584 hash table entry. */
5586 index_map = xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
5587 for (i = 0; i < expr_hash_table.size; i++)
5588 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
5589 index_map[expr->bitmap_index] = expr;
5591 /* Reset bitmap used to track which insns are redundant. */
5592 pre_redundant_insns = sbitmap_alloc (max_cuid);
5593 sbitmap_zero (pre_redundant_insns);
5595 /* Delete the redundant insns first so that
5596 - we know what register to use for the new insns and for the other
5597 ones with reaching expressions
5598 - we know which insns are redundant when we go to create copies */
5600 changed = pre_delete ();
5602 did_insert = pre_edge_insert (edge_list, index_map);
5604 /* In other places with reaching expressions, copy the expression to the
5605 specially allocated pseudo-reg that reaches the redundant expr. */
5606 pre_insert_copies ();
5609 commit_edge_insertions ();
5614 sbitmap_free (pre_redundant_insns);
5618 /* Top level routine to perform one PRE GCSE pass.
5620 Return nonzero if a change was made. */
5623 one_pre_gcse_pass (int pass)
5627 gcse_subst_count = 0;
5628 gcse_create_count = 0;
5630 alloc_hash_table (max_cuid, &expr_hash_table, 0);
5631 add_noreturn_fake_exit_edges ();
5633 compute_ld_motion_mems ();
5635 compute_hash_table (&expr_hash_table);
5636 trim_ld_motion_mems ();
5638 dump_hash_table (gcse_file, "Expression", &expr_hash_table);
5640 if (expr_hash_table.n_elems > 0)
5642 alloc_pre_mem (last_basic_block, expr_hash_table.n_elems);
5643 compute_pre_data ();
5644 changed |= pre_gcse ();
5645 free_edge_list (edge_list);
5650 remove_fake_edges ();
5651 free_hash_table (&expr_hash_table);
5655 fprintf (gcse_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
5656 current_function_name, pass, bytes_used);
5657 fprintf (gcse_file, "%d substs, %d insns created\n",
5658 gcse_subst_count, gcse_create_count);
5664 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
5665 If notes are added to an insn which references a CODE_LABEL, the
5666 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
5667 because the following loop optimization pass requires them. */
5669 /* ??? This is very similar to the loop.c add_label_notes function. We
5670 could probably share code here. */
5672 /* ??? If there was a jump optimization pass after gcse and before loop,
5673 then we would not need to do this here, because jump would add the
5674 necessary REG_LABEL notes. */
5677 add_label_notes (rtx x, rtx insn)
5679 enum rtx_code code = GET_CODE (x);
5683 if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
5685 /* This code used to ignore labels that referred to dispatch tables to
5686 avoid flow generating (slightly) worse code.
5688 We no longer ignore such label references (see LABEL_REF handling in
5689 mark_jump_label for additional information). */
5691 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0),
5693 if (LABEL_P (XEXP (x, 0)))
5694 LABEL_NUSES (XEXP (x, 0))++;
5698 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
5701 add_label_notes (XEXP (x, i), insn);
5702 else if (fmt[i] == 'E')
5703 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5704 add_label_notes (XVECEXP (x, i, j), insn);
5708 /* Compute transparent outgoing information for each block.
5710 An expression is transparent to an edge unless it is killed by
5711 the edge itself. This can only happen with abnormal control flow,
5712 when the edge is traversed through a call. This happens with
5713 non-local labels and exceptions.
5715 This would not be necessary if we split the edge. While this is
5716 normally impossible for abnormal critical edges, with some effort
5717 it should be possible with exception handling, since we still have
5718 control over which handler should be invoked. But due to increased
5719 EH table sizes, this may not be worthwhile. */
5722 compute_transpout (void)
5728 sbitmap_vector_ones (transpout, last_basic_block);
5732 /* Note that flow inserted a nop a the end of basic blocks that
5733 end in call instructions for reasons other than abnormal
5735 if (GET_CODE (bb->end) != CALL_INSN)
5738 for (i = 0; i < expr_hash_table.size; i++)
5739 for (expr = expr_hash_table.table[i]; expr ; expr = expr->next_same_hash)
5740 if (GET_CODE (expr->expr) == MEM)
5742 if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
5743 && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
5746 /* ??? Optimally, we would use interprocedural alias
5747 analysis to determine if this mem is actually killed
5749 RESET_BIT (transpout[bb->index], expr->bitmap_index);
5754 /* Removal of useless null pointer checks */
5756 /* Called via note_stores. X is set by SETTER. If X is a register we must
5757 invalidate nonnull_local and set nonnull_killed. DATA is really a
5758 `null_pointer_info *'.
5760 We ignore hard registers. */
5763 invalidate_nonnull_info (rtx x, rtx setter ATTRIBUTE_UNUSED, void *data)
5766 struct null_pointer_info *npi = (struct null_pointer_info *) data;
5768 while (GET_CODE (x) == SUBREG)
5771 /* Ignore anything that is not a register or is a hard register. */
5772 if (GET_CODE (x) != REG
5773 || REGNO (x) < npi->min_reg
5774 || REGNO (x) >= npi->max_reg)
5777 regno = REGNO (x) - npi->min_reg;
5779 RESET_BIT (npi->nonnull_local[npi->current_block->index], regno);
5780 SET_BIT (npi->nonnull_killed[npi->current_block->index], regno);
5783 /* Do null-pointer check elimination for the registers indicated in
5784 NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
5785 they are not our responsibility to free. */
5788 delete_null_pointer_checks_1 (unsigned int *block_reg, sbitmap *nonnull_avin,
5789 sbitmap *nonnull_avout,
5790 struct null_pointer_info *npi)
5792 basic_block bb, current_block;
5793 sbitmap *nonnull_local = npi->nonnull_local;
5794 sbitmap *nonnull_killed = npi->nonnull_killed;
5795 int something_changed = 0;
5797 /* Compute local properties, nonnull and killed. A register will have
5798 the nonnull property if at the end of the current block its value is
5799 known to be nonnull. The killed property indicates that somewhere in
5800 the block any information we had about the register is killed.
5802 Note that a register can have both properties in a single block. That
5803 indicates that it's killed, then later in the block a new value is
5805 sbitmap_vector_zero (nonnull_local, last_basic_block);
5806 sbitmap_vector_zero (nonnull_killed, last_basic_block);
5808 FOR_EACH_BB (current_block)
5810 rtx insn, stop_insn;
5812 /* Set the current block for invalidate_nonnull_info. */
5813 npi->current_block = current_block;
5815 /* Scan each insn in the basic block looking for memory references and
5817 stop_insn = NEXT_INSN (current_block->end);
5818 for (insn = current_block->head;
5820 insn = NEXT_INSN (insn))
5825 /* Ignore anything that is not a normal insn. */
5826 if (! INSN_P (insn))
5829 /* Basically ignore anything that is not a simple SET. We do have
5830 to make sure to invalidate nonnull_local and set nonnull_killed
5831 for such insns though. */
5832 set = single_set (insn);
5835 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5839 /* See if we've got a usable memory load. We handle it first
5840 in case it uses its address register as a dest (which kills
5841 the nonnull property). */
5842 if (GET_CODE (SET_SRC (set)) == MEM
5843 && GET_CODE ((reg = XEXP (SET_SRC (set), 0))) == REG
5844 && REGNO (reg) >= npi->min_reg
5845 && REGNO (reg) < npi->max_reg)
5846 SET_BIT (nonnull_local[current_block->index],
5847 REGNO (reg) - npi->min_reg);
5849 /* Now invalidate stuff clobbered by this insn. */
5850 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5852 /* And handle stores, we do these last since any sets in INSN can
5853 not kill the nonnull property if it is derived from a MEM
5854 appearing in a SET_DEST. */
5855 if (GET_CODE (SET_DEST (set)) == MEM
5856 && GET_CODE ((reg = XEXP (SET_DEST (set), 0))) == REG
5857 && REGNO (reg) >= npi->min_reg
5858 && REGNO (reg) < npi->max_reg)
5859 SET_BIT (nonnull_local[current_block->index],
5860 REGNO (reg) - npi->min_reg);
5864 /* Now compute global properties based on the local properties. This
5865 is a classic global availability algorithm. */
5866 compute_available (nonnull_local, nonnull_killed,
5867 nonnull_avout, nonnull_avin);
5869 /* Now look at each bb and see if it ends with a compare of a value
5873 rtx last_insn = bb->end;
5874 rtx condition, earliest;
5875 int compare_and_branch;
5877 /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
5878 since BLOCK_REG[BB] is zero if this block did not end with a
5879 comparison against zero, this condition works. */
5880 if (block_reg[bb->index] < npi->min_reg
5881 || block_reg[bb->index] >= npi->max_reg)
5884 /* LAST_INSN is a conditional jump. Get its condition. */
5885 condition = get_condition (last_insn, &earliest, false);
5887 /* If we can't determine the condition then skip. */
5891 /* Is the register known to have a nonzero value? */
5892 if (!TEST_BIT (nonnull_avout[bb->index], block_reg[bb->index] - npi->min_reg))
5895 /* Try to compute whether the compare/branch at the loop end is one or
5896 two instructions. */
5897 if (earliest == last_insn)
5898 compare_and_branch = 1;
5899 else if (earliest == prev_nonnote_insn (last_insn))
5900 compare_and_branch = 2;
5904 /* We know the register in this comparison is nonnull at exit from
5905 this block. We can optimize this comparison. */
5906 if (GET_CODE (condition) == NE)
5910 new_jump = emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn)),
5912 JUMP_LABEL (new_jump) = JUMP_LABEL (last_insn);
5913 LABEL_NUSES (JUMP_LABEL (new_jump))++;
5914 emit_barrier_after (new_jump);
5917 something_changed = 1;
5918 delete_insn (last_insn);
5919 if (compare_and_branch == 2)
5920 delete_insn (earliest);
5921 purge_dead_edges (bb);
5923 /* Don't check this block again. (Note that BLOCK_END is
5924 invalid here; we deleted the last instruction in the
5926 block_reg[bb->index] = 0;
5929 return something_changed;
5932 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
5935 This is conceptually similar to global constant/copy propagation and
5936 classic global CSE (it even uses the same dataflow equations as cprop).
5938 If a register is used as memory address with the form (mem (reg)), then we
5939 know that REG can not be zero at that point in the program. Any instruction
5940 which sets REG "kills" this property.
5942 So, if every path leading to a conditional branch has an available memory
5943 reference of that form, then we know the register can not have the value
5944 zero at the conditional branch.
5946 So we merely need to compute the local properties and propagate that data
5947 around the cfg, then optimize where possible.
5949 We run this pass two times. Once before CSE, then again after CSE. This
5950 has proven to be the most profitable approach. It is rare for new
5951 optimization opportunities of this nature to appear after the first CSE
5954 This could probably be integrated with global cprop with a little work. */
5957 delete_null_pointer_checks (rtx f ATTRIBUTE_UNUSED)
5959 sbitmap *nonnull_avin, *nonnull_avout;
5960 unsigned int *block_reg;
5964 int max_reg = max_reg_num ();
5965 struct null_pointer_info npi;
5966 int something_changed = 0;
5968 /* If we have only a single block, or it is too expensive, give up. */
5969 if (n_basic_blocks <= 1
5970 || is_too_expensive (_ ("NULL pointer checks disabled")))
5973 /* We need four bitmaps, each with a bit for each register in each
5975 regs_per_pass = get_bitmap_width (4, last_basic_block, max_reg);
5977 /* Allocate bitmaps to hold local and global properties. */
5978 npi.nonnull_local = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5979 npi.nonnull_killed = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5980 nonnull_avin = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5981 nonnull_avout = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
5983 /* Go through the basic blocks, seeing whether or not each block
5984 ends with a conditional branch whose condition is a comparison
5985 against zero. Record the register compared in BLOCK_REG. */
5986 block_reg = xcalloc (last_basic_block, sizeof (int));
5989 rtx last_insn = bb->end;
5990 rtx condition, earliest, reg;
5992 /* We only want conditional branches. */
5993 if (GET_CODE (last_insn) != JUMP_INSN
5994 || !any_condjump_p (last_insn)
5995 || !onlyjump_p (last_insn))
5998 /* LAST_INSN is a conditional jump. Get its condition. */
5999 condition = get_condition (last_insn, &earliest, false);
6001 /* If we were unable to get the condition, or it is not an equality
6002 comparison against zero then there's nothing we can do. */
6004 || (GET_CODE (condition) != NE && GET_CODE (condition) != EQ)
6005 || GET_CODE (XEXP (condition, 1)) != CONST_INT
6006 || (XEXP (condition, 1)
6007 != CONST0_RTX (GET_MODE (XEXP (condition, 0)))))
6010 /* We must be checking a register against zero. */
6011 reg = XEXP (condition, 0);
6012 if (GET_CODE (reg) != REG)
6015 block_reg[bb->index] = REGNO (reg);
6018 /* Go through the algorithm for each block of registers. */
6019 for (reg = FIRST_PSEUDO_REGISTER; reg < max_reg; reg += regs_per_pass)
6022 npi.max_reg = MIN (reg + regs_per_pass, max_reg);
6023 something_changed |= delete_null_pointer_checks_1 (block_reg,
6029 /* Free the table of registers compared at the end of every block. */
6033 sbitmap_vector_free (npi.nonnull_local);
6034 sbitmap_vector_free (npi.nonnull_killed);
6035 sbitmap_vector_free (nonnull_avin);
6036 sbitmap_vector_free (nonnull_avout);
6038 return something_changed;
6041 /* Code Hoisting variables and subroutines. */
6043 /* Very busy expressions. */
6044 static sbitmap *hoist_vbein;
6045 static sbitmap *hoist_vbeout;
6047 /* Hoistable expressions. */
6048 static sbitmap *hoist_exprs;
6050 /* Dominator bitmaps. */
6051 dominance_info dominators;
6053 /* ??? We could compute post dominators and run this algorithm in
6054 reverse to perform tail merging, doing so would probably be
6055 more effective than the tail merging code in jump.c.
6057 It's unclear if tail merging could be run in parallel with
6058 code hoisting. It would be nice. */
6060 /* Allocate vars used for code hoisting analysis. */
6063 alloc_code_hoist_mem (int n_blocks, int n_exprs)
6065 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
6066 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
6067 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
6069 hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
6070 hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
6071 hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
6072 transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
6075 /* Free vars used for code hoisting analysis. */
6078 free_code_hoist_mem (void)
6080 sbitmap_vector_free (antloc);
6081 sbitmap_vector_free (transp);
6082 sbitmap_vector_free (comp);
6084 sbitmap_vector_free (hoist_vbein);
6085 sbitmap_vector_free (hoist_vbeout);
6086 sbitmap_vector_free (hoist_exprs);
6087 sbitmap_vector_free (transpout);
6089 free_dominance_info (dominators);
6092 /* Compute the very busy expressions at entry/exit from each block.
6094 An expression is very busy if all paths from a given point
6095 compute the expression. */
6098 compute_code_hoist_vbeinout (void)
6100 int changed, passes;
6103 sbitmap_vector_zero (hoist_vbeout, last_basic_block);
6104 sbitmap_vector_zero (hoist_vbein, last_basic_block);
6113 /* We scan the blocks in the reverse order to speed up
6115 FOR_EACH_BB_REVERSE (bb)
6117 changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index], antloc[bb->index],
6118 hoist_vbeout[bb->index], transp[bb->index]);
6119 if (bb->next_bb != EXIT_BLOCK_PTR)
6120 sbitmap_intersection_of_succs (hoist_vbeout[bb->index], hoist_vbein, bb->index);
6127 fprintf (gcse_file, "hoisting vbeinout computation: %d passes\n", passes);
6130 /* Top level routine to do the dataflow analysis needed by code hoisting. */
6133 compute_code_hoist_data (void)
6135 compute_local_properties (transp, comp, antloc, &expr_hash_table);
6136 compute_transpout ();
6137 compute_code_hoist_vbeinout ();
6138 dominators = calculate_dominance_info (CDI_DOMINATORS);
6140 fprintf (gcse_file, "\n");
6143 /* Determine if the expression identified by EXPR_INDEX would
6144 reach BB unimpared if it was placed at the end of EXPR_BB.
6146 It's unclear exactly what Muchnick meant by "unimpared". It seems
6147 to me that the expression must either be computed or transparent in
6148 *every* block in the path(s) from EXPR_BB to BB. Any other definition
6149 would allow the expression to be hoisted out of loops, even if
6150 the expression wasn't a loop invariant.
6152 Contrast this to reachability for PRE where an expression is
6153 considered reachable if *any* path reaches instead of *all*
6157 hoist_expr_reaches_here_p (basic_block expr_bb, int expr_index, basic_block bb, char *visited)
6160 int visited_allocated_locally = 0;
6163 if (visited == NULL)
6165 visited_allocated_locally = 1;
6166 visited = xcalloc (last_basic_block, 1);
6169 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
6171 basic_block pred_bb = pred->src;
6173 if (pred->src == ENTRY_BLOCK_PTR)
6175 else if (pred_bb == expr_bb)
6177 else if (visited[pred_bb->index])
6180 /* Does this predecessor generate this expression? */
6181 else if (TEST_BIT (comp[pred_bb->index], expr_index))
6183 else if (! TEST_BIT (transp[pred_bb->index], expr_index))
6189 visited[pred_bb->index] = 1;
6190 if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
6195 if (visited_allocated_locally)
6198 return (pred == NULL);
6201 /* Actually perform code hoisting. */
6206 basic_block bb, dominated;
6208 unsigned int domby_len;
6210 struct expr **index_map;
6213 sbitmap_vector_zero (hoist_exprs, last_basic_block);
6215 /* Compute a mapping from expression number (`bitmap_index') to
6216 hash table entry. */
6218 index_map = xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
6219 for (i = 0; i < expr_hash_table.size; i++)
6220 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
6221 index_map[expr->bitmap_index] = expr;
6223 /* Walk over each basic block looking for potentially hoistable
6224 expressions, nothing gets hoisted from the entry block. */
6228 int insn_inserted_p;
6230 domby_len = get_dominated_by (dominators, bb, &domby);
6231 /* Examine each expression that is very busy at the exit of this
6232 block. These are the potentially hoistable expressions. */
6233 for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++)
6237 if (TEST_BIT (hoist_vbeout[bb->index], i)
6238 && TEST_BIT (transpout[bb->index], i))
6240 /* We've found a potentially hoistable expression, now
6241 we look at every block BB dominates to see if it
6242 computes the expression. */
6243 for (j = 0; j < domby_len; j++)
6245 dominated = domby[j];
6246 /* Ignore self dominance. */
6247 if (bb == dominated)
6249 /* We've found a dominated block, now see if it computes
6250 the busy expression and whether or not moving that
6251 expression to the "beginning" of that block is safe. */
6252 if (!TEST_BIT (antloc[dominated->index], i))
6255 /* Note if the expression would reach the dominated block
6256 unimpared if it was placed at the end of BB.
6258 Keep track of how many times this expression is hoistable
6259 from a dominated block into BB. */
6260 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
6264 /* If we found more than one hoistable occurrence of this
6265 expression, then note it in the bitmap of expressions to
6266 hoist. It makes no sense to hoist things which are computed
6267 in only one BB, and doing so tends to pessimize register
6268 allocation. One could increase this value to try harder
6269 to avoid any possible code expansion due to register
6270 allocation issues; however experiments have shown that
6271 the vast majority of hoistable expressions are only movable
6272 from two successors, so raising this threshold is likely
6273 to nullify any benefit we get from code hoisting. */
6276 SET_BIT (hoist_exprs[bb->index], i);
6281 /* If we found nothing to hoist, then quit now. */
6288 /* Loop over all the hoistable expressions. */
6289 for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++)
6291 /* We want to insert the expression into BB only once, so
6292 note when we've inserted it. */
6293 insn_inserted_p = 0;
6295 /* These tests should be the same as the tests above. */
6296 if (TEST_BIT (hoist_vbeout[bb->index], i))
6298 /* We've found a potentially hoistable expression, now
6299 we look at every block BB dominates to see if it
6300 computes the expression. */
6301 for (j = 0; j < domby_len; j++)
6303 dominated = domby[j];
6304 /* Ignore self dominance. */
6305 if (bb == dominated)
6308 /* We've found a dominated block, now see if it computes
6309 the busy expression and whether or not moving that
6310 expression to the "beginning" of that block is safe. */
6311 if (!TEST_BIT (antloc[dominated->index], i))
6314 /* The expression is computed in the dominated block and
6315 it would be safe to compute it at the start of the
6316 dominated block. Now we have to determine if the
6317 expression would reach the dominated block if it was
6318 placed at the end of BB. */
6319 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
6321 struct expr *expr = index_map[i];
6322 struct occr *occr = expr->antic_occr;
6326 /* Find the right occurrence of this expression. */
6327 while (BLOCK_FOR_INSN (occr->insn) != dominated && occr)
6330 /* Should never happen. */
6336 set = single_set (insn);
6340 /* Create a pseudo-reg to store the result of reaching
6341 expressions into. Get the mode for the new pseudo
6342 from the mode of the original destination pseudo. */
6343 if (expr->reaching_reg == NULL)
6345 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
6347 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
6349 occr->deleted_p = 1;
6350 if (!insn_inserted_p)
6352 insert_insn_end_bb (index_map[i], bb, 0);
6353 insn_inserted_p = 1;
6365 /* Top level routine to perform one code hoisting (aka unification) pass
6367 Return nonzero if a change was made. */
6370 one_code_hoisting_pass (void)
6374 alloc_hash_table (max_cuid, &expr_hash_table, 0);
6375 compute_hash_table (&expr_hash_table);
6377 dump_hash_table (gcse_file, "Code Hosting Expressions", &expr_hash_table);
6379 if (expr_hash_table.n_elems > 0)
6381 alloc_code_hoist_mem (last_basic_block, expr_hash_table.n_elems);
6382 compute_code_hoist_data ();
6384 free_code_hoist_mem ();
6387 free_hash_table (&expr_hash_table);
6392 /* Here we provide the things required to do store motion towards
6393 the exit. In order for this to be effective, gcse also needed to
6394 be taught how to move a load when it is kill only by a store to itself.
6399 void foo(float scale)
6401 for (i=0; i<10; i++)
6405 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
6406 the load out since its live around the loop, and stored at the bottom
6409 The 'Load Motion' referred to and implemented in this file is
6410 an enhancement to gcse which when using edge based lcm, recognizes
6411 this situation and allows gcse to move the load out of the loop.
6413 Once gcse has hoisted the load, store motion can then push this
6414 load towards the exit, and we end up with no loads or stores of 'i'
6417 /* This will search the ldst list for a matching expression. If it
6418 doesn't find one, we create one and initialize it. */
6420 static struct ls_expr *
6423 struct ls_expr * ptr;
6425 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
6426 if (expr_equiv_p (ptr->pattern, x))
6431 ptr = xmalloc (sizeof (struct ls_expr));
6433 ptr->next = pre_ldst_mems;
6436 ptr->pattern_regs = NULL_RTX;
6437 ptr->loads = NULL_RTX;
6438 ptr->stores = NULL_RTX;
6439 ptr->reaching_reg = NULL_RTX;
6442 ptr->hash_index = 0;
6443 pre_ldst_mems = ptr;
6449 /* Free up an individual ldst entry. */
6452 free_ldst_entry (struct ls_expr * ptr)
6454 free_INSN_LIST_list (& ptr->loads);
6455 free_INSN_LIST_list (& ptr->stores);
6460 /* Free up all memory associated with the ldst list. */
6463 free_ldst_mems (void)
6465 while (pre_ldst_mems)
6467 struct ls_expr * tmp = pre_ldst_mems;
6469 pre_ldst_mems = pre_ldst_mems->next;
6471 free_ldst_entry (tmp);
6474 pre_ldst_mems = NULL;
6477 /* Dump debugging info about the ldst list. */
6480 print_ldst_list (FILE * file)
6482 struct ls_expr * ptr;
6484 fprintf (file, "LDST list: \n");
6486 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
6488 fprintf (file, " Pattern (%3d): ", ptr->index);
6490 print_rtl (file, ptr->pattern);
6492 fprintf (file, "\n Loads : ");
6495 print_rtl (file, ptr->loads);
6497 fprintf (file, "(nil)");
6499 fprintf (file, "\n Stores : ");
6502 print_rtl (file, ptr->stores);
6504 fprintf (file, "(nil)");
6506 fprintf (file, "\n\n");
6509 fprintf (file, "\n");
6512 /* Returns 1 if X is in the list of ldst only expressions. */
6514 static struct ls_expr *
6515 find_rtx_in_ldst (rtx x)
6517 struct ls_expr * ptr;
6519 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6520 if (expr_equiv_p (ptr->pattern, x) && ! ptr->invalid)
6526 /* Assign each element of the list of mems a monotonically increasing value. */
6529 enumerate_ldsts (void)
6531 struct ls_expr * ptr;
6534 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6540 /* Return first item in the list. */
6542 static inline struct ls_expr *
6543 first_ls_expr (void)
6545 return pre_ldst_mems;
6548 /* Return the next item in the list after the specified one. */
6550 static inline struct ls_expr *
6551 next_ls_expr (struct ls_expr * ptr)
6556 /* Load Motion for loads which only kill themselves. */
6558 /* Return true if x is a simple MEM operation, with no registers or
6559 side effects. These are the types of loads we consider for the
6560 ld_motion list, otherwise we let the usual aliasing take care of it. */
6565 if (GET_CODE (x) != MEM)
6568 if (MEM_VOLATILE_P (x))
6571 if (GET_MODE (x) == BLKmode)
6574 /* If we are handling exceptions, we must be careful with memory references
6575 that may trap. If we are not, the behavior is undefined, so we may just
6577 if (flag_non_call_exceptions && may_trap_p (x))
6580 if (side_effects_p (x))
6583 /* Do not consider function arguments passed on stack. */
6584 if (reg_mentioned_p (stack_pointer_rtx, x))
6587 if (flag_float_store && FLOAT_MODE_P (GET_MODE (x)))
6593 /* Make sure there isn't a buried reference in this pattern anywhere.
6594 If there is, invalidate the entry for it since we're not capable
6595 of fixing it up just yet.. We have to be sure we know about ALL
6596 loads since the aliasing code will allow all entries in the
6597 ld_motion list to not-alias itself. If we miss a load, we will get
6598 the wrong value since gcse might common it and we won't know to
6602 invalidate_any_buried_refs (rtx x)
6606 struct ls_expr * ptr;
6608 /* Invalidate it in the list. */
6609 if (GET_CODE (x) == MEM && simple_mem (x))
6611 ptr = ldst_entry (x);
6615 /* Recursively process the insn. */
6616 fmt = GET_RTX_FORMAT (GET_CODE (x));
6618 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
6621 invalidate_any_buried_refs (XEXP (x, i));
6622 else if (fmt[i] == 'E')
6623 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6624 invalidate_any_buried_refs (XVECEXP (x, i, j));
6628 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
6629 being defined as MEM loads and stores to symbols, with no side effects
6630 and no registers in the expression. For a MEM destination, we also
6631 check that the insn is still valid if we replace the destination with a
6632 REG, as is done in update_ld_motion_stores. If there are any uses/defs
6633 which don't match this criteria, they are invalidated and trimmed out
6637 compute_ld_motion_mems (void)
6639 struct ls_expr * ptr;
6643 pre_ldst_mems = NULL;
6647 for (insn = bb->head;
6648 insn && insn != NEXT_INSN (bb->end);
6649 insn = NEXT_INSN (insn))
6653 if (GET_CODE (PATTERN (insn)) == SET)
6655 rtx src = SET_SRC (PATTERN (insn));
6656 rtx dest = SET_DEST (PATTERN (insn));
6658 /* Check for a simple LOAD... */
6659 if (GET_CODE (src) == MEM && simple_mem (src))
6661 ptr = ldst_entry (src);
6662 if (GET_CODE (dest) == REG)
6663 ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
6669 /* Make sure there isn't a buried load somewhere. */
6670 invalidate_any_buried_refs (src);
6673 /* Check for stores. Don't worry about aliased ones, they
6674 will block any movement we might do later. We only care
6675 about this exact pattern since those are the only
6676 circumstance that we will ignore the aliasing info. */
6677 if (GET_CODE (dest) == MEM && simple_mem (dest))
6679 ptr = ldst_entry (dest);
6681 if (GET_CODE (src) != MEM
6682 && GET_CODE (src) != ASM_OPERANDS
6683 /* Check for REG manually since want_to_gcse_p
6684 returns 0 for all REGs. */
6685 && (REG_P (src) || want_to_gcse_p (src)))
6686 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
6692 invalidate_any_buried_refs (PATTERN (insn));
6698 /* Remove any references that have been either invalidated or are not in the
6699 expression list for pre gcse. */
6702 trim_ld_motion_mems (void)
6704 struct ls_expr * last = NULL;
6705 struct ls_expr * ptr = first_ls_expr ();
6709 int del = ptr->invalid;
6710 struct expr * expr = NULL;
6712 /* Delete if entry has been made invalid. */
6718 /* Delete if we cannot find this mem in the expression list. */
6719 for (i = 0; i < expr_hash_table.size && del; i++)
6721 for (expr = expr_hash_table.table[i];
6723 expr = expr->next_same_hash)
6724 if (expr_equiv_p (expr->expr, ptr->pattern))
6736 last->next = ptr->next;
6737 free_ldst_entry (ptr);
6742 pre_ldst_mems = pre_ldst_mems->next;
6743 free_ldst_entry (ptr);
6744 ptr = pre_ldst_mems;
6749 /* Set the expression field if we are keeping it. */
6756 /* Show the world what we've found. */
6757 if (gcse_file && pre_ldst_mems != NULL)
6758 print_ldst_list (gcse_file);
6761 /* This routine will take an expression which we are replacing with
6762 a reaching register, and update any stores that are needed if
6763 that expression is in the ld_motion list. Stores are updated by
6764 copying their SRC to the reaching register, and then storing
6765 the reaching register into the store location. These keeps the
6766 correct value in the reaching register for the loads. */
6769 update_ld_motion_stores (struct expr * expr)
6771 struct ls_expr * mem_ptr;
6773 if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
6775 /* We can try to find just the REACHED stores, but is shouldn't
6776 matter to set the reaching reg everywhere... some might be
6777 dead and should be eliminated later. */
6779 /* We replace (set mem expr) with (set reg expr) (set mem reg)
6780 where reg is the reaching reg used in the load. We checked in
6781 compute_ld_motion_mems that we can replace (set mem expr) with
6782 (set reg expr) in that insn. */
6783 rtx list = mem_ptr->stores;
6785 for ( ; list != NULL_RTX; list = XEXP (list, 1))
6787 rtx insn = XEXP (list, 0);
6788 rtx pat = PATTERN (insn);
6789 rtx src = SET_SRC (pat);
6790 rtx reg = expr->reaching_reg;
6793 /* If we've already copied it, continue. */
6794 if (expr->reaching_reg == src)
6799 fprintf (gcse_file, "PRE: store updated with reaching reg ");
6800 print_rtl (gcse_file, expr->reaching_reg);
6801 fprintf (gcse_file, ":\n ");
6802 print_inline_rtx (gcse_file, insn, 8);
6803 fprintf (gcse_file, "\n");
6806 copy = gen_move_insn ( reg, copy_rtx (SET_SRC (pat)));
6807 new = emit_insn_before (copy, insn);
6808 record_one_set (REGNO (reg), new);
6809 SET_SRC (pat) = reg;
6811 /* un-recognize this pattern since it's probably different now. */
6812 INSN_CODE (insn) = -1;
6813 gcse_create_count++;
6818 /* Store motion code. */
6820 #define ANTIC_STORE_LIST(x) ((x)->loads)
6821 #define AVAIL_STORE_LIST(x) ((x)->stores)
6822 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
6824 /* This is used to communicate the target bitvector we want to use in the
6825 reg_set_info routine when called via the note_stores mechanism. */
6826 static int * regvec;
6828 /* And current insn, for the same routine. */
6829 static rtx compute_store_table_current_insn;
6831 /* Used in computing the reverse edge graph bit vectors. */
6832 static sbitmap * st_antloc;
6834 /* Global holding the number of store expressions we are dealing with. */
6835 static int num_stores;
6837 /* Checks to set if we need to mark a register set. Called from note_stores. */
6840 reg_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED,
6841 void *data ATTRIBUTE_UNUSED)
6843 if (GET_CODE (dest) == SUBREG)
6844 dest = SUBREG_REG (dest);
6846 if (GET_CODE (dest) == REG)
6847 regvec[REGNO (dest)] = INSN_UID (compute_store_table_current_insn);
6850 /* Return zero if some of the registers in list X are killed
6851 due to set of registers in bitmap REGS_SET. */
6854 store_ops_ok (rtx x, int *regs_set)
6858 for (; x; x = XEXP (x, 1))
6861 if (regs_set[REGNO(reg)])
6868 /* Returns a list of registers mentioned in X. */
6870 extract_mentioned_regs (rtx x)
6872 return extract_mentioned_regs_helper (x, NULL_RTX);
6875 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
6878 extract_mentioned_regs_helper (rtx x, rtx accum)
6884 /* Repeat is used to turn tail-recursion into iteration. */
6890 code = GET_CODE (x);
6894 return alloc_EXPR_LIST (0, x, accum);
6904 /* We do not run this function with arguments having side effects. */
6923 i = GET_RTX_LENGTH (code) - 1;
6924 fmt = GET_RTX_FORMAT (code);
6930 rtx tem = XEXP (x, i);
6932 /* If we are about to do the last recursive call
6933 needed at this level, change it into iteration. */
6940 accum = extract_mentioned_regs_helper (tem, accum);
6942 else if (fmt[i] == 'E')
6946 for (j = 0; j < XVECLEN (x, i); j++)
6947 accum = extract_mentioned_regs_helper (XVECEXP (x, i, j), accum);
6954 /* Determine whether INSN is MEM store pattern that we will consider moving.
6955 REGS_SET_BEFORE is bitmap of registers set before (and including) the
6956 current insn, REGS_SET_AFTER is bitmap of registers set after (and
6957 including) the insn in this basic block. We must be passing through BB from
6958 head to end, as we are using this fact to speed things up.
6960 The results are stored this way:
6962 -- the first anticipatable expression is added into ANTIC_STORE_LIST
6963 -- if the processed expression is not anticipatable, NULL_RTX is added
6964 there instead, so that we can use it as indicator that no further
6965 expression of this type may be anticipatable
6966 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
6967 consequently, all of them but this head are dead and may be deleted.
6968 -- if the expression is not available, the insn due to that it fails to be
6969 available is stored in reaching_reg.
6971 The things are complicated a bit by fact that there already may be stores
6972 to the same MEM from other blocks; also caller must take care of the
6973 necessary cleanup of the temporary markers after end of the basic block.
6977 find_moveable_store (rtx insn, int *regs_set_before, int *regs_set_after)
6979 struct ls_expr * ptr;
6981 int check_anticipatable, check_available;
6982 basic_block bb = BLOCK_FOR_INSN (insn);
6984 set = single_set (insn);
6988 dest = SET_DEST (set);
6990 if (GET_CODE (dest) != MEM || MEM_VOLATILE_P (dest)
6991 || GET_MODE (dest) == BLKmode)
6994 if (side_effects_p (dest))
6997 /* If we are handling exceptions, we must be careful with memory references
6998 that may trap. If we are not, the behavior is undefined, so we may just
7000 if (flag_non_call_exceptions && may_trap_p (dest))
7003 ptr = ldst_entry (dest);
7004 if (!ptr->pattern_regs)
7005 ptr->pattern_regs = extract_mentioned_regs (dest);
7007 /* Do not check for anticipatability if we either found one anticipatable
7008 store already, or tested for one and found out that it was killed. */
7009 check_anticipatable = 0;
7010 if (!ANTIC_STORE_LIST (ptr))
7011 check_anticipatable = 1;
7014 tmp = XEXP (ANTIC_STORE_LIST (ptr), 0);
7016 && BLOCK_FOR_INSN (tmp) != bb)
7017 check_anticipatable = 1;
7019 if (check_anticipatable)
7021 if (store_killed_before (dest, ptr->pattern_regs, insn, bb, regs_set_before))
7025 ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (tmp,
7026 ANTIC_STORE_LIST (ptr));
7029 /* It is not necessary to check whether store is available if we did
7030 it successfully before; if we failed before, do not bother to check
7031 until we reach the insn that caused us to fail. */
7032 check_available = 0;
7033 if (!AVAIL_STORE_LIST (ptr))
7034 check_available = 1;
7037 tmp = XEXP (AVAIL_STORE_LIST (ptr), 0);
7038 if (BLOCK_FOR_INSN (tmp) != bb)
7039 check_available = 1;
7041 if (check_available)
7043 /* Check that we have already reached the insn at that the check
7044 failed last time. */
7045 if (LAST_AVAIL_CHECK_FAILURE (ptr))
7048 tmp != insn && tmp != LAST_AVAIL_CHECK_FAILURE (ptr);
7049 tmp = PREV_INSN (tmp))
7052 check_available = 0;
7055 check_available = store_killed_after (dest, ptr->pattern_regs, insn,
7057 &LAST_AVAIL_CHECK_FAILURE (ptr));
7059 if (!check_available)
7060 AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn, AVAIL_STORE_LIST (ptr));
7063 /* Find available and anticipatable stores. */
7066 compute_store_table (void)
7072 int *last_set_in, *already_set;
7073 struct ls_expr * ptr, **prev_next_ptr_ptr;
7075 max_gcse_regno = max_reg_num ();
7077 reg_set_in_block = sbitmap_vector_alloc (last_basic_block,
7079 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
7081 last_set_in = xmalloc (sizeof (int) * max_gcse_regno);
7082 already_set = xmalloc (sizeof (int) * max_gcse_regno);
7084 /* Find all the stores we care about. */
7087 /* First compute the registers set in this block. */
7088 memset (last_set_in, 0, sizeof (int) * max_gcse_regno);
7089 regvec = last_set_in;
7091 for (insn = bb->head;
7092 insn != NEXT_INSN (bb->end);
7093 insn = NEXT_INSN (insn))
7095 if (! INSN_P (insn))
7098 if (GET_CODE (insn) == CALL_INSN)
7100 bool clobbers_all = false;
7101 #ifdef NON_SAVING_SETJMP
7102 if (NON_SAVING_SETJMP
7103 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
7104 clobbers_all = true;
7107 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
7109 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
7110 last_set_in[regno] = INSN_UID (insn);
7113 pat = PATTERN (insn);
7114 compute_store_table_current_insn = insn;
7115 note_stores (pat, reg_set_info, NULL);
7118 /* Record the set registers. */
7119 for (regno = 0; regno < max_gcse_regno; regno++)
7120 if (last_set_in[regno])
7121 SET_BIT (reg_set_in_block[bb->index], regno);
7123 /* Now find the stores. */
7124 memset (already_set, 0, sizeof (int) * max_gcse_regno);
7125 regvec = already_set;
7126 for (insn = bb->head;
7127 insn != NEXT_INSN (bb->end);
7128 insn = NEXT_INSN (insn))
7130 if (! INSN_P (insn))
7133 if (GET_CODE (insn) == CALL_INSN)
7135 bool clobbers_all = false;
7136 #ifdef NON_SAVING_SETJMP
7137 if (NON_SAVING_SETJMP
7138 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
7139 clobbers_all = true;
7142 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
7144 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
7145 already_set[regno] = 1;
7148 pat = PATTERN (insn);
7149 note_stores (pat, reg_set_info, NULL);
7151 /* Now that we've marked regs, look for stores. */
7152 find_moveable_store (insn, already_set, last_set_in);
7154 /* Unmark regs that are no longer set. */
7155 for (regno = 0; regno < max_gcse_regno; regno++)
7156 if (last_set_in[regno] == INSN_UID (insn))
7157 last_set_in[regno] = 0;
7160 /* Clear temporary marks. */
7161 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7163 LAST_AVAIL_CHECK_FAILURE(ptr) = NULL_RTX;
7164 if (ANTIC_STORE_LIST (ptr)
7165 && (tmp = XEXP (ANTIC_STORE_LIST (ptr), 0)) == NULL_RTX)
7166 ANTIC_STORE_LIST (ptr) = XEXP (ANTIC_STORE_LIST (ptr), 1);
7170 /* Remove the stores that are not available anywhere, as there will
7171 be no opportunity to optimize them. */
7172 for (ptr = pre_ldst_mems, prev_next_ptr_ptr = &pre_ldst_mems;
7174 ptr = *prev_next_ptr_ptr)
7176 if (!AVAIL_STORE_LIST (ptr))
7178 *prev_next_ptr_ptr = ptr->next;
7179 free_ldst_entry (ptr);
7182 prev_next_ptr_ptr = &ptr->next;
7185 ret = enumerate_ldsts ();
7189 fprintf (gcse_file, "ST_avail and ST_antic (shown under loads..)\n");
7190 print_ldst_list (gcse_file);
7198 /* Check to see if the load X is aliased with STORE_PATTERN.
7199 AFTER is true if we are checking the case when STORE_PATTERN occurs
7203 load_kills_store (rtx x, rtx store_pattern, int after)
7206 return anti_dependence (x, store_pattern);
7208 return true_dependence (store_pattern, GET_MODE (store_pattern), x,
7212 /* Go through the entire insn X, looking for any loads which might alias
7213 STORE_PATTERN. Return true if found.
7214 AFTER is true if we are checking the case when STORE_PATTERN occurs
7215 after the insn X. */
7218 find_loads (rtx x, rtx store_pattern, int after)
7227 if (GET_CODE (x) == SET)
7230 if (GET_CODE (x) == MEM)
7232 if (load_kills_store (x, store_pattern, after))
7236 /* Recursively process the insn. */
7237 fmt = GET_RTX_FORMAT (GET_CODE (x));
7239 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
7242 ret |= find_loads (XEXP (x, i), store_pattern, after);
7243 else if (fmt[i] == 'E')
7244 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
7245 ret |= find_loads (XVECEXP (x, i, j), store_pattern, after);
7250 /* Check if INSN kills the store pattern X (is aliased with it).
7251 AFTER is true if we are checking the case when store X occurs
7252 after the insn. Return true if it it does. */
7255 store_killed_in_insn (rtx x, rtx x_regs, rtx insn, int after)
7262 if (GET_CODE (insn) == CALL_INSN)
7264 /* A normal or pure call might read from pattern,
7265 but a const call will not. */
7266 if (! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn))
7269 /* But even a const call reads its parameters. Check whether the
7270 base of some of registers used in mem is stack pointer. */
7271 for (reg = x_regs; reg; reg = XEXP (reg, 1))
7273 base = find_base_term (XEXP (reg, 0));
7275 || (GET_CODE (base) == ADDRESS
7276 && GET_MODE (base) == Pmode
7277 && XEXP (base, 0) == stack_pointer_rtx))
7284 if (GET_CODE (PATTERN (insn)) == SET)
7286 rtx pat = PATTERN (insn);
7287 rtx dest = SET_DEST (pat);
7289 if (GET_CODE (dest) == SIGN_EXTRACT
7290 || GET_CODE (dest) == ZERO_EXTRACT)
7291 dest = XEXP (dest, 0);
7293 /* Check for memory stores to aliased objects. */
7294 if (GET_CODE (dest) == MEM
7295 && !expr_equiv_p (dest, x))
7299 if (output_dependence (dest, x))
7304 if (output_dependence (x, dest))
7308 return find_loads (SET_SRC (pat), x, after);
7311 return find_loads (PATTERN (insn), x, after);
7314 /* Returns true if the expression X is loaded or clobbered on or after INSN
7315 within basic block BB. REGS_SET_AFTER is bitmap of registers set in
7316 or after the insn. X_REGS is list of registers mentioned in X. If the store
7317 is killed, return the last insn in that it occurs in FAIL_INSN. */
7320 store_killed_after (rtx x, rtx x_regs, rtx insn, basic_block bb,
7321 int *regs_set_after, rtx *fail_insn)
7323 rtx last = bb->end, act;
7325 if (!store_ops_ok (x_regs, regs_set_after))
7327 /* We do not know where it will happen. */
7329 *fail_insn = NULL_RTX;
7333 /* Scan from the end, so that fail_insn is determined correctly. */
7334 for (act = last; act != PREV_INSN (insn); act = PREV_INSN (act))
7335 if (store_killed_in_insn (x, x_regs, act, false))
7345 /* Returns true if the expression X is loaded or clobbered on or before INSN
7346 within basic block BB. X_REGS is list of registers mentioned in X.
7347 REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
7349 store_killed_before (rtx x, rtx x_regs, rtx insn, basic_block bb,
7350 int *regs_set_before)
7352 rtx first = bb->head;
7354 if (!store_ops_ok (x_regs, regs_set_before))
7357 for ( ; insn != PREV_INSN (first); insn = PREV_INSN (insn))
7358 if (store_killed_in_insn (x, x_regs, insn, true))
7364 /* Fill in available, anticipatable, transparent and kill vectors in
7365 STORE_DATA, based on lists of available and anticipatable stores. */
7367 build_store_vectors (void)
7370 int *regs_set_in_block;
7372 struct ls_expr * ptr;
7375 /* Build the gen_vector. This is any store in the table which is not killed
7376 by aliasing later in its block. */
7377 ae_gen = sbitmap_vector_alloc (last_basic_block, num_stores);
7378 sbitmap_vector_zero (ae_gen, last_basic_block);
7380 st_antloc = sbitmap_vector_alloc (last_basic_block, num_stores);
7381 sbitmap_vector_zero (st_antloc, last_basic_block);
7383 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7385 for (st = AVAIL_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
7387 insn = XEXP (st, 0);
7388 bb = BLOCK_FOR_INSN (insn);
7390 /* If we've already seen an available expression in this block,
7391 we can delete this one (It occurs earlier in the block). We'll
7392 copy the SRC expression to an unused register in case there
7393 are any side effects. */
7394 if (TEST_BIT (ae_gen[bb->index], ptr->index))
7396 rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
7398 fprintf (gcse_file, "Removing redundant store:\n");
7399 replace_store_insn (r, XEXP (st, 0), bb);
7402 SET_BIT (ae_gen[bb->index], ptr->index);
7405 for (st = ANTIC_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
7407 insn = XEXP (st, 0);
7408 bb = BLOCK_FOR_INSN (insn);
7409 SET_BIT (st_antloc[bb->index], ptr->index);
7413 ae_kill = sbitmap_vector_alloc (last_basic_block, num_stores);
7414 sbitmap_vector_zero (ae_kill, last_basic_block);
7416 transp = sbitmap_vector_alloc (last_basic_block, num_stores);
7417 sbitmap_vector_zero (transp, last_basic_block);
7418 regs_set_in_block = xmalloc (sizeof (int) * max_gcse_regno);
7422 for (regno = 0; regno < max_gcse_regno; regno++)
7423 regs_set_in_block[regno] = TEST_BIT (reg_set_in_block[bb->index], regno);
7425 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7427 if (store_killed_after (ptr->pattern, ptr->pattern_regs, bb->head,
7428 bb, regs_set_in_block, NULL))
7430 /* It should not be necessary to consider the expression
7431 killed if it is both anticipatable and available. */
7432 if (!TEST_BIT (st_antloc[bb->index], ptr->index)
7433 || !TEST_BIT (ae_gen[bb->index], ptr->index))
7434 SET_BIT (ae_kill[bb->index], ptr->index);
7437 SET_BIT (transp[bb->index], ptr->index);
7441 free (regs_set_in_block);
7445 dump_sbitmap_vector (gcse_file, "st_antloc", "", st_antloc, last_basic_block);
7446 dump_sbitmap_vector (gcse_file, "st_kill", "", ae_kill, last_basic_block);
7447 dump_sbitmap_vector (gcse_file, "Transpt", "", transp, last_basic_block);
7448 dump_sbitmap_vector (gcse_file, "st_avloc", "", ae_gen, last_basic_block);
7452 /* Insert an instruction at the beginning of a basic block, and update
7453 the BLOCK_HEAD if needed. */
7456 insert_insn_start_bb (rtx insn, basic_block bb)
7458 /* Insert at start of successor block. */
7459 rtx prev = PREV_INSN (bb->head);
7460 rtx before = bb->head;
7463 if (GET_CODE (before) != CODE_LABEL
7464 && (GET_CODE (before) != NOTE
7465 || NOTE_LINE_NUMBER (before) != NOTE_INSN_BASIC_BLOCK))
7468 if (prev == bb->end)
7470 before = NEXT_INSN (before);
7473 insn = emit_insn_after (insn, prev);
7477 fprintf (gcse_file, "STORE_MOTION insert store at start of BB %d:\n",
7479 print_inline_rtx (gcse_file, insn, 6);
7480 fprintf (gcse_file, "\n");
7484 /* This routine will insert a store on an edge. EXPR is the ldst entry for
7485 the memory reference, and E is the edge to insert it on. Returns nonzero
7486 if an edge insertion was performed. */
7489 insert_store (struct ls_expr * expr, edge e)
7495 /* We did all the deleted before this insert, so if we didn't delete a
7496 store, then we haven't set the reaching reg yet either. */
7497 if (expr->reaching_reg == NULL_RTX)
7500 if (e->flags & EDGE_FAKE)
7503 reg = expr->reaching_reg;
7504 insn = gen_move_insn (copy_rtx (expr->pattern), reg);
7506 /* If we are inserting this expression on ALL predecessor edges of a BB,
7507 insert it at the start of the BB, and reset the insert bits on the other
7508 edges so we don't try to insert it on the other edges. */
7510 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
7511 if (!(tmp->flags & EDGE_FAKE))
7513 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
7514 if (index == EDGE_INDEX_NO_EDGE)
7516 if (! TEST_BIT (pre_insert_map[index], expr->index))
7520 /* If tmp is NULL, we found an insertion on every edge, blank the
7521 insertion vector for these edges, and insert at the start of the BB. */
7522 if (!tmp && bb != EXIT_BLOCK_PTR)
7524 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
7526 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
7527 RESET_BIT (pre_insert_map[index], expr->index);
7529 insert_insn_start_bb (insn, bb);
7533 /* We can't insert on this edge, so we'll insert at the head of the
7534 successors block. See Morgan, sec 10.5. */
7535 if ((e->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
7537 insert_insn_start_bb (insn, bb);
7541 insert_insn_on_edge (insn, e);
7545 fprintf (gcse_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
7546 e->src->index, e->dest->index);
7547 print_inline_rtx (gcse_file, insn, 6);
7548 fprintf (gcse_file, "\n");
7554 /* This routine will replace a store with a SET to a specified register. */
7557 replace_store_insn (rtx reg, rtx del, basic_block bb)
7561 insn = gen_move_insn (reg, SET_SRC (single_set (del)));
7562 insn = emit_insn_after (insn, del);
7567 "STORE_MOTION delete insn in BB %d:\n ", bb->index);
7568 print_inline_rtx (gcse_file, del, 6);
7569 fprintf (gcse_file, "\nSTORE MOTION replaced with insn:\n ");
7570 print_inline_rtx (gcse_file, insn, 6);
7571 fprintf (gcse_file, "\n");
7578 /* Delete a store, but copy the value that would have been stored into
7579 the reaching_reg for later storing. */
7582 delete_store (struct ls_expr * expr, basic_block bb)
7586 if (expr->reaching_reg == NULL_RTX)
7587 expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
7589 reg = expr->reaching_reg;
7591 for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
7594 if (BLOCK_FOR_INSN (del) == bb)
7596 /* We know there is only one since we deleted redundant
7597 ones during the available computation. */
7598 replace_store_insn (reg, del, bb);
7604 /* Free memory used by store motion. */
7607 free_store_memory (void)
7612 sbitmap_vector_free (ae_gen);
7614 sbitmap_vector_free (ae_kill);
7616 sbitmap_vector_free (transp);
7618 sbitmap_vector_free (st_antloc);
7620 sbitmap_vector_free (pre_insert_map);
7622 sbitmap_vector_free (pre_delete_map);
7623 if (reg_set_in_block)
7624 sbitmap_vector_free (reg_set_in_block);
7626 ae_gen = ae_kill = transp = st_antloc = NULL;
7627 pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
7630 /* Perform store motion. Much like gcse, except we move expressions the
7631 other way by looking at the flowgraph in reverse. */
7638 struct ls_expr * ptr;
7639 int update_flow = 0;
7643 fprintf (gcse_file, "before store motion\n");
7644 print_rtl (gcse_file, get_insns ());
7647 init_alias_analysis ();
7649 /* Find all the available and anticipatable stores. */
7650 num_stores = compute_store_table ();
7651 if (num_stores == 0)
7653 sbitmap_vector_free (reg_set_in_block);
7654 end_alias_analysis ();
7658 /* Now compute kill & transp vectors. */
7659 build_store_vectors ();
7660 add_noreturn_fake_exit_edges ();
7661 connect_infinite_loops_to_exit ();
7663 edge_list = pre_edge_rev_lcm (gcse_file, num_stores, transp, ae_gen,
7664 st_antloc, ae_kill, &pre_insert_map,
7667 /* Now we want to insert the new stores which are going to be needed. */
7668 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7671 if (TEST_BIT (pre_delete_map[bb->index], ptr->index))
7672 delete_store (ptr, bb);
7674 for (x = 0; x < NUM_EDGES (edge_list); x++)
7675 if (TEST_BIT (pre_insert_map[x], ptr->index))
7676 update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
7680 commit_edge_insertions ();
7682 free_store_memory ();
7683 free_edge_list (edge_list);
7684 remove_fake_edges ();
7685 end_alias_analysis ();
7689 /* Entry point for jump bypassing optimization pass. */
7692 bypass_jumps (FILE *file)
7696 /* We do not construct an accurate cfg in functions which call
7697 setjmp, so just punt to be safe. */
7698 if (current_function_calls_setjmp)
7701 /* For calling dump_foo fns from gdb. */
7702 debug_stderr = stderr;
7705 /* Identify the basic block information for this function, including
7706 successors and predecessors. */
7707 max_gcse_regno = max_reg_num ();
7710 dump_flow_info (file);
7712 /* Return if there's nothing to do, or it is too expensive */
7713 if (n_basic_blocks <= 1 || is_too_expensive (_ ("jump bypassing disabled")))
7716 gcc_obstack_init (&gcse_obstack);
7719 /* We need alias. */
7720 init_alias_analysis ();
7722 /* Record where pseudo-registers are set. This data is kept accurate
7723 during each pass. ??? We could also record hard-reg information here
7724 [since it's unchanging], however it is currently done during hash table
7727 It may be tempting to compute MEM set information here too, but MEM sets
7728 will be subject to code motion one day and thus we need to compute
7729 information about memory sets when we build the hash tables. */
7731 alloc_reg_set_mem (max_gcse_regno);
7732 compute_sets (get_insns ());
7734 max_gcse_regno = max_reg_num ();
7735 alloc_gcse_mem (get_insns ());
7736 changed = one_cprop_pass (1, 1, 1);
7741 fprintf (file, "BYPASS of %s: %d basic blocks, ",
7742 current_function_name, n_basic_blocks);
7743 fprintf (file, "%d bytes\n\n", bytes_used);
7746 obstack_free (&gcse_obstack, NULL);
7747 free_reg_set_mem ();
7749 /* We are finished with alias. */
7750 end_alias_analysis ();
7751 allocate_reg_info (max_reg_num (), FALSE, FALSE);
7756 /* Return true if the graph is too expensive to optimize. PASS is the
7757 optimization about to be performed. */
7760 is_too_expensive (const char *pass)
7762 /* Trying to perform global optimizations on flow graphs which have
7763 a high connectivity will take a long time and is unlikely to be
7764 particularly useful.
7766 In normal circumstances a cfg should have about twice as many
7767 edges as blocks. But we do not want to punish small functions
7768 which have a couple switch statements. Rather than simply
7769 threshold the number of blocks, uses something with a more
7770 graceful degradation. */
7771 if (n_edges > 20000 + n_basic_blocks * 4)
7773 if (warn_disabled_optimization)
7774 warning ("%s: %d basic blocks and %d edges/basic block",
7775 pass, n_basic_blocks, n_edges / n_basic_blocks);
7780 /* If allocating memory for the cprop bitmap would take up too much
7781 storage it's better just to disable the optimization. */
7783 * SBITMAP_SET_SIZE (max_reg_num ())
7784 * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
7786 if (warn_disabled_optimization)
7787 warning ("%s: %d basic blocks and %d registers",
7788 pass, n_basic_blocks, max_reg_num ());
7796 #include "gt-gcse.h"