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 /* Nonzero for each mode that supports (set (reg) (reg)).
303 This is trivially true for integer and floating point values.
304 It may or may not be true for condition codes. */
305 static char can_copy_p
[(int) NUM_MACHINE_MODES
];
307 /* Nonzero if can_copy_p has been initialized. */
308 static int can_copy_init_p
;
310 struct reg_use
{rtx reg_rtx
; };
312 /* Hash table of expressions. */
316 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
318 /* Index in the available expression bitmaps. */
320 /* Next entry with the same hash. */
321 struct expr
*next_same_hash
;
322 /* List of anticipatable occurrences in basic blocks in the function.
323 An "anticipatable occurrence" is one that is the first occurrence in the
324 basic block, the operands are not modified in the basic block prior
325 to the occurrence and the output is not used between the start of
326 the block and the occurrence. */
327 struct occr
*antic_occr
;
328 /* List of available occurrence in basic blocks in the function.
329 An "available occurrence" is one that is the last occurrence in the
330 basic block and the operands are not modified by following statements in
331 the basic block [including this insn]. */
332 struct occr
*avail_occr
;
333 /* Non-null if the computation is PRE redundant.
334 The value is the newly created pseudo-reg to record a copy of the
335 expression in all the places that reach the redundant copy. */
339 /* Occurrence of an expression.
340 There is one per basic block. If a pattern appears more than once the
341 last appearance is used [or first for anticipatable expressions]. */
345 /* Next occurrence of this expression. */
347 /* The insn that computes the expression. */
349 /* Nonzero if this [anticipatable] occurrence has been deleted. */
351 /* Nonzero if this [available] occurrence has been copied to
353 /* ??? This is mutually exclusive with deleted_p, so they could share
358 /* Expression and copy propagation hash tables.
359 Each hash table is an array of buckets.
360 ??? It is known that if it were an array of entries, structure elements
361 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
362 not clear whether in the final analysis a sufficient amount of memory would
363 be saved as the size of the available expression bitmaps would be larger
364 [one could build a mapping table without holes afterwards though].
365 Someday I'll perform the computation and figure it out. */
370 This is an array of `expr_hash_table_size' elements. */
373 /* Size of the hash table, in elements. */
376 /* Number of hash table elements. */
377 unsigned int n_elems
;
379 /* Whether the table is expression of copy propagation one. */
383 /* Expression hash table. */
384 static struct hash_table expr_hash_table
;
386 /* Copy propagation hash table. */
387 static struct hash_table set_hash_table
;
389 /* Mapping of uids to cuids.
390 Only real insns get cuids. */
391 static int *uid_cuid
;
393 /* Highest UID in UID_CUID. */
396 /* Get the cuid of an insn. */
397 #ifdef ENABLE_CHECKING
398 #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
400 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
403 /* Number of cuids. */
406 /* Mapping of cuids to insns. */
407 static rtx
*cuid_insn
;
409 /* Get insn from cuid. */
410 #define CUID_INSN(CUID) (cuid_insn[CUID])
412 /* Maximum register number in function prior to doing gcse + 1.
413 Registers created during this pass have regno >= max_gcse_regno.
414 This is named with "gcse" to not collide with global of same name. */
415 static unsigned int max_gcse_regno
;
417 /* Table of registers that are modified.
419 For each register, each element is a list of places where the pseudo-reg
422 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
423 requires knowledge of which blocks kill which regs [and thus could use
424 a bitmap instead of the lists `reg_set_table' uses].
426 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
427 num-regs) [however perhaps it may be useful to keep the data as is]. One
428 advantage of recording things this way is that `reg_set_table' is fairly
429 sparse with respect to pseudo regs but for hard regs could be fairly dense
430 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
431 up functions like compute_transp since in the case of pseudo-regs we only
432 need to iterate over the number of times a pseudo-reg is set, not over the
433 number of basic blocks [clearly there is a bit of a slow down in the cases
434 where a pseudo is set more than once in a block, however it is believed
435 that the net effect is to speed things up]. This isn't done for hard-regs
436 because recording call-clobbered hard-regs in `reg_set_table' at each
437 function call can consume a fair bit of memory, and iterating over
438 hard-regs stored this way in compute_transp will be more expensive. */
440 typedef struct reg_set
442 /* The next setting of this register. */
443 struct reg_set
*next
;
444 /* The insn where it was set. */
448 static reg_set
**reg_set_table
;
450 /* Size of `reg_set_table'.
451 The table starts out at max_gcse_regno + slop, and is enlarged as
453 static int reg_set_table_size
;
455 /* Amount to grow `reg_set_table' by when it's full. */
456 #define REG_SET_TABLE_SLOP 100
458 /* This is a list of expressions which are MEMs and will be used by load
460 Load motion tracks MEMs which aren't killed by
461 anything except itself. (ie, loads and stores to a single location).
462 We can then allow movement of these MEM refs with a little special
463 allowance. (all stores copy the same value to the reaching reg used
464 for the loads). This means all values used to store into memory must have
465 no side effects so we can re-issue the setter value.
466 Store Motion uses this structure as an expression table to track stores
467 which look interesting, and might be moveable towards the exit block. */
471 struct expr
* expr
; /* Gcse expression reference for LM. */
472 rtx pattern
; /* Pattern of this mem. */
473 rtx loads
; /* INSN list of loads seen. */
474 rtx stores
; /* INSN list of stores seen. */
475 struct ls_expr
* next
; /* Next in the list. */
476 int invalid
; /* Invalid for some reason. */
477 int index
; /* If it maps to a bitmap index. */
478 int hash_index
; /* Index when in a hash table. */
479 rtx reaching_reg
; /* Register to use when re-writing. */
482 /* Array of implicit set patterns indexed by basic block index. */
483 static rtx
*implicit_sets
;
485 /* Head of the list of load/store memory refs. */
486 static struct ls_expr
* pre_ldst_mems
= NULL
;
488 /* Bitmap containing one bit for each register in the program.
489 Used when performing GCSE to track which registers have been set since
490 the start of the basic block. */
491 static regset reg_set_bitmap
;
493 /* For each block, a bitmap of registers set in the block.
494 This is used by expr_killed_p and compute_transp.
495 It is computed during hash table computation and not by compute_sets
496 as it includes registers added since the last pass (or between cprop and
497 gcse) and it's currently not easy to realloc sbitmap vectors. */
498 static sbitmap
*reg_set_in_block
;
500 /* Array, indexed by basic block number for a list of insns which modify
501 memory within that block. */
502 static rtx
* modify_mem_list
;
503 bitmap modify_mem_list_set
;
505 /* This array parallels modify_mem_list, but is kept canonicalized. */
506 static rtx
* canon_modify_mem_list
;
507 bitmap canon_modify_mem_list_set
;
508 /* Various variables for statistics gathering. */
510 /* Memory used in a pass.
511 This isn't intended to be absolutely precise. Its intent is only
512 to keep an eye on memory usage. */
513 static int bytes_used
;
515 /* GCSE substitutions made. */
516 static int gcse_subst_count
;
517 /* Number of copy instructions created. */
518 static int gcse_create_count
;
519 /* Number of constants propagated. */
520 static int const_prop_count
;
521 /* Number of copys propagated. */
522 static int copy_prop_count
;
524 /* These variables are used by classic GCSE.
525 Normally they'd be defined a bit later, but `rd_gen' needs to
526 be declared sooner. */
528 /* Each block has a bitmap of each type.
529 The length of each blocks bitmap is:
531 max_cuid - for reaching definitions
532 n_exprs - for available expressions
534 Thus we view the bitmaps as 2 dimensional arrays. i.e.
535 rd_kill[block_num][cuid_num]
536 ae_kill[block_num][expr_num] */
538 /* For reaching defs */
539 static sbitmap
*rd_kill
, *rd_gen
, *reaching_defs
, *rd_out
;
541 /* for available exprs */
542 static sbitmap
*ae_kill
, *ae_gen
, *ae_in
, *ae_out
;
544 /* Objects of this type are passed around by the null-pointer check
546 struct null_pointer_info
548 /* The basic block being processed. */
549 basic_block current_block
;
550 /* The first register to be handled in this pass. */
551 unsigned int min_reg
;
552 /* One greater than the last register to be handled in this pass. */
553 unsigned int max_reg
;
554 sbitmap
*nonnull_local
;
555 sbitmap
*nonnull_killed
;
558 static void compute_can_copy
PARAMS ((void));
559 static char *gmalloc
PARAMS ((unsigned int));
560 static char *grealloc
PARAMS ((char *, unsigned int));
561 static char *gcse_alloc
PARAMS ((unsigned long));
562 static void alloc_gcse_mem
PARAMS ((rtx
));
563 static void free_gcse_mem
PARAMS ((void));
564 static void alloc_reg_set_mem
PARAMS ((int));
565 static void free_reg_set_mem
PARAMS ((void));
566 static int get_bitmap_width
PARAMS ((int, int, int));
567 static void record_one_set
PARAMS ((int, rtx
));
568 static void record_set_info
PARAMS ((rtx
, rtx
, void *));
569 static void compute_sets
PARAMS ((rtx
));
570 static void hash_scan_insn
PARAMS ((rtx
, struct hash_table
*, int));
571 static void hash_scan_set
PARAMS ((rtx
, rtx
, struct hash_table
*));
572 static void hash_scan_clobber
PARAMS ((rtx
, rtx
, struct hash_table
*));
573 static void hash_scan_call
PARAMS ((rtx
, rtx
, struct hash_table
*));
574 static int want_to_gcse_p
PARAMS ((rtx
));
575 static int oprs_unchanged_p
PARAMS ((rtx
, rtx
, int));
576 static int oprs_anticipatable_p
PARAMS ((rtx
, rtx
));
577 static int oprs_available_p
PARAMS ((rtx
, rtx
));
578 static void insert_expr_in_table
PARAMS ((rtx
, enum machine_mode
, rtx
,
579 int, int, struct hash_table
*));
580 static void insert_set_in_table
PARAMS ((rtx
, rtx
, struct hash_table
*));
581 static unsigned int hash_expr
PARAMS ((rtx
, enum machine_mode
, int *, int));
582 static unsigned int hash_expr_1
PARAMS ((rtx
, enum machine_mode
, int *));
583 static unsigned int hash_string_1
PARAMS ((const char *));
584 static unsigned int hash_set
PARAMS ((int, int));
585 static int expr_equiv_p
PARAMS ((rtx
, rtx
));
586 static void record_last_reg_set_info
PARAMS ((rtx
, int));
587 static void record_last_mem_set_info
PARAMS ((rtx
));
588 static void record_last_set_info
PARAMS ((rtx
, rtx
, void *));
589 static void compute_hash_table
PARAMS ((struct hash_table
*));
590 static void alloc_hash_table
PARAMS ((int, struct hash_table
*, int));
591 static void free_hash_table
PARAMS ((struct hash_table
*));
592 static void compute_hash_table_work
PARAMS ((struct hash_table
*));
593 static void dump_hash_table
PARAMS ((FILE *, const char *,
594 struct hash_table
*));
595 static struct expr
*lookup_expr
PARAMS ((rtx
, struct hash_table
*));
596 static struct expr
*lookup_set
PARAMS ((unsigned int, struct hash_table
*));
597 static struct expr
*next_set
PARAMS ((unsigned int, struct expr
*));
598 static void reset_opr_set_tables
PARAMS ((void));
599 static int oprs_not_set_p
PARAMS ((rtx
, rtx
));
600 static void mark_call
PARAMS ((rtx
));
601 static void mark_set
PARAMS ((rtx
, rtx
));
602 static void mark_clobber
PARAMS ((rtx
, rtx
));
603 static void mark_oprs_set
PARAMS ((rtx
));
604 static void alloc_cprop_mem
PARAMS ((int, int));
605 static void free_cprop_mem
PARAMS ((void));
606 static void compute_transp
PARAMS ((rtx
, int, sbitmap
*, int));
607 static void compute_transpout
PARAMS ((void));
608 static void compute_local_properties
PARAMS ((sbitmap
*, sbitmap
*, sbitmap
*,
609 struct hash_table
*));
610 static void compute_cprop_data
PARAMS ((void));
611 static void find_used_regs
PARAMS ((rtx
*, void *));
612 static int try_replace_reg
PARAMS ((rtx
, rtx
, rtx
));
613 static struct expr
*find_avail_set
PARAMS ((int, rtx
));
614 static int cprop_jump
PARAMS ((basic_block
, rtx
, rtx
, rtx
, rtx
));
615 static void mems_conflict_for_gcse_p
PARAMS ((rtx
, rtx
, void *));
616 static int load_killed_in_block_p
PARAMS ((basic_block
, int, rtx
, int));
617 static void canon_list_insert
PARAMS ((rtx
, rtx
, void *));
618 static int cprop_insn
PARAMS ((rtx
, int));
619 static int cprop
PARAMS ((int));
620 static rtx fis_get_condition
PARAMS ((rtx
));
621 static void find_implicit_sets
PARAMS ((void));
622 static int one_cprop_pass
PARAMS ((int, int, int));
623 static bool constprop_register
PARAMS ((rtx
, rtx
, rtx
, int));
624 static struct expr
*find_bypass_set
PARAMS ((int, int));
625 static int bypass_block
PARAMS ((basic_block
, rtx
, rtx
));
626 static int bypass_conditional_jumps
PARAMS ((void));
627 static void alloc_pre_mem
PARAMS ((int, int));
628 static void free_pre_mem
PARAMS ((void));
629 static void compute_pre_data
PARAMS ((void));
630 static int pre_expr_reaches_here_p
PARAMS ((basic_block
, struct expr
*,
632 static void insert_insn_end_bb
PARAMS ((struct expr
*, basic_block
, int));
633 static void pre_insert_copy_insn
PARAMS ((struct expr
*, rtx
));
634 static void pre_insert_copies
PARAMS ((void));
635 static int pre_delete
PARAMS ((void));
636 static int pre_gcse
PARAMS ((void));
637 static int one_pre_gcse_pass
PARAMS ((int));
638 static void add_label_notes
PARAMS ((rtx
, rtx
));
639 static void alloc_code_hoist_mem
PARAMS ((int, int));
640 static void free_code_hoist_mem
PARAMS ((void));
641 static void compute_code_hoist_vbeinout
PARAMS ((void));
642 static void compute_code_hoist_data
PARAMS ((void));
643 static int hoist_expr_reaches_here_p
PARAMS ((basic_block
, int, basic_block
,
645 static void hoist_code
PARAMS ((void));
646 static int one_code_hoisting_pass
PARAMS ((void));
647 static void alloc_rd_mem
PARAMS ((int, int));
648 static void free_rd_mem
PARAMS ((void));
649 static void handle_rd_kill_set
PARAMS ((rtx
, int, basic_block
));
650 static void compute_kill_rd
PARAMS ((void));
651 static void compute_rd
PARAMS ((void));
652 static void alloc_avail_expr_mem
PARAMS ((int, int));
653 static void free_avail_expr_mem
PARAMS ((void));
654 static void compute_ae_gen
PARAMS ((struct hash_table
*));
655 static int expr_killed_p
PARAMS ((rtx
, basic_block
));
656 static void compute_ae_kill
PARAMS ((sbitmap
*, sbitmap
*, struct hash_table
*));
657 static int expr_reaches_here_p
PARAMS ((struct occr
*, struct expr
*,
659 static rtx computing_insn
PARAMS ((struct expr
*, rtx
));
660 static int def_reaches_here_p
PARAMS ((rtx
, rtx
));
661 static int can_disregard_other_sets
PARAMS ((struct reg_set
**, rtx
, int));
662 static int handle_avail_expr
PARAMS ((rtx
, struct expr
*));
663 static int classic_gcse
PARAMS ((void));
664 static int one_classic_gcse_pass
PARAMS ((int));
665 static void invalidate_nonnull_info
PARAMS ((rtx
, rtx
, void *));
666 static int delete_null_pointer_checks_1
PARAMS ((unsigned int *,
667 sbitmap
*, sbitmap
*,
668 struct null_pointer_info
*));
669 static rtx process_insert_insn
PARAMS ((struct expr
*));
670 static int pre_edge_insert
PARAMS ((struct edge_list
*, struct expr
**));
671 static int expr_reaches_here_p_work
PARAMS ((struct occr
*, struct expr
*,
672 basic_block
, int, char *));
673 static int pre_expr_reaches_here_p_work
PARAMS ((basic_block
, struct expr
*,
674 basic_block
, char *));
675 static struct ls_expr
* ldst_entry
PARAMS ((rtx
));
676 static void free_ldst_entry
PARAMS ((struct ls_expr
*));
677 static void free_ldst_mems
PARAMS ((void));
678 static void print_ldst_list
PARAMS ((FILE *));
679 static struct ls_expr
* find_rtx_in_ldst
PARAMS ((rtx
));
680 static int enumerate_ldsts
PARAMS ((void));
681 static inline struct ls_expr
* first_ls_expr
PARAMS ((void));
682 static inline struct ls_expr
* next_ls_expr
PARAMS ((struct ls_expr
*));
683 static int simple_mem
PARAMS ((rtx
));
684 static void invalidate_any_buried_refs
PARAMS ((rtx
));
685 static void compute_ld_motion_mems
PARAMS ((void));
686 static void trim_ld_motion_mems
PARAMS ((void));
687 static void update_ld_motion_stores
PARAMS ((struct expr
*));
688 static void reg_set_info
PARAMS ((rtx
, rtx
, void *));
689 static int store_ops_ok
PARAMS ((rtx
, basic_block
));
690 static void find_moveable_store
PARAMS ((rtx
));
691 static int compute_store_table
PARAMS ((void));
692 static int load_kills_store
PARAMS ((rtx
, rtx
));
693 static int find_loads
PARAMS ((rtx
, rtx
));
694 static int store_killed_in_insn
PARAMS ((rtx
, rtx
));
695 static int store_killed_after
PARAMS ((rtx
, rtx
, basic_block
));
696 static int store_killed_before
PARAMS ((rtx
, rtx
, basic_block
));
697 static void build_store_vectors
PARAMS ((void));
698 static void insert_insn_start_bb
PARAMS ((rtx
, basic_block
));
699 static int insert_store
PARAMS ((struct ls_expr
*, edge
));
700 static void replace_store_insn
PARAMS ((rtx
, rtx
, basic_block
));
701 static void delete_store
PARAMS ((struct ls_expr
*,
703 static void free_store_memory
PARAMS ((void));
704 static void store_motion
PARAMS ((void));
705 static void free_insn_expr_list_list
PARAMS ((rtx
*));
706 static void clear_modify_mem_tables
PARAMS ((void));
707 static void free_modify_mem_tables
PARAMS ((void));
708 static rtx gcse_emit_move_after
PARAMS ((rtx
, rtx
, rtx
));
709 static void local_cprop_find_used_regs
PARAMS ((rtx
*, void *));
710 static bool do_local_cprop
PARAMS ((rtx
, rtx
, int, rtx
*));
711 static bool adjust_libcall_notes
PARAMS ((rtx
, rtx
, rtx
, rtx
*));
712 static void local_cprop_pass
PARAMS ((int));
714 /* Entry point for global common subexpression elimination.
715 F is the first instruction in the function. */
723 /* Bytes used at start of pass. */
724 int initial_bytes_used
;
725 /* Maximum number of bytes used by a pass. */
727 /* Point to release obstack data from for each pass. */
728 char *gcse_obstack_bottom
;
730 /* We do not construct an accurate cfg in functions which call
731 setjmp, so just punt to be safe. */
732 if (current_function_calls_setjmp
)
735 /* Assume that we do not need to run jump optimizations after gcse. */
736 run_jump_opt_after_gcse
= 0;
738 /* For calling dump_foo fns from gdb. */
739 debug_stderr
= stderr
;
742 /* Identify the basic block information for this function, including
743 successors and predecessors. */
744 max_gcse_regno
= max_reg_num ();
747 dump_flow_info (file
);
749 /* Return if there's nothing to do. */
750 if (n_basic_blocks
<= 1)
753 /* Trying to perform global optimizations on flow graphs which have
754 a high connectivity will take a long time and is unlikely to be
757 In normal circumstances a cfg should have about twice as many edges
758 as blocks. But we do not want to punish small functions which have
759 a couple switch statements. So we require a relatively large number
760 of basic blocks and the ratio of edges to blocks to be high. */
761 if (n_basic_blocks
> 1000 && n_edges
/ n_basic_blocks
>= 20)
763 if (warn_disabled_optimization
)
764 warning ("GCSE disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
765 n_basic_blocks
, n_edges
/ n_basic_blocks
);
769 /* If allocating memory for the cprop bitmap would take up too much
770 storage it's better just to disable the optimization. */
772 * SBITMAP_SET_SIZE (max_gcse_regno
)
773 * sizeof (SBITMAP_ELT_TYPE
)) > MAX_GCSE_MEMORY
)
775 if (warn_disabled_optimization
)
776 warning ("GCSE disabled: %d basic blocks and %d registers",
777 n_basic_blocks
, max_gcse_regno
);
782 /* See what modes support reg/reg copy operations. */
783 if (! can_copy_init_p
)
789 gcc_obstack_init (&gcse_obstack
);
793 init_alias_analysis ();
794 /* Record where pseudo-registers are set. This data is kept accurate
795 during each pass. ??? We could also record hard-reg information here
796 [since it's unchanging], however it is currently done during hash table
799 It may be tempting to compute MEM set information here too, but MEM sets
800 will be subject to code motion one day and thus we need to compute
801 information about memory sets when we build the hash tables. */
803 alloc_reg_set_mem (max_gcse_regno
);
807 initial_bytes_used
= bytes_used
;
809 gcse_obstack_bottom
= gcse_alloc (1);
811 while (changed
&& pass
< MAX_GCSE_PASSES
)
815 fprintf (file
, "GCSE pass %d\n\n", pass
+ 1);
817 /* Initialize bytes_used to the space for the pred/succ lists,
818 and the reg_set_table data. */
819 bytes_used
= initial_bytes_used
;
821 /* Each pass may create new registers, so recalculate each time. */
822 max_gcse_regno
= max_reg_num ();
826 /* Don't allow constant propagation to modify jumps
828 changed
= one_cprop_pass (pass
+ 1, 0, 0);
831 changed
|= one_classic_gcse_pass (pass
+ 1);
834 changed
|= one_pre_gcse_pass (pass
+ 1);
835 /* We may have just created new basic blocks. Release and
836 recompute various things which are sized on the number of
840 free_modify_mem_tables ();
842 = (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
843 canon_modify_mem_list
844 = (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
845 memset ((char *) modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
846 memset ((char *) canon_modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
849 alloc_reg_set_mem (max_reg_num ());
851 run_jump_opt_after_gcse
= 1;
854 if (max_pass_bytes
< bytes_used
)
855 max_pass_bytes
= bytes_used
;
857 /* Free up memory, then reallocate for code hoisting. We can
858 not re-use the existing allocated memory because the tables
859 will not have info for the insns or registers created by
860 partial redundancy elimination. */
863 /* It does not make sense to run code hoisting unless we optimizing
864 for code size -- it rarely makes programs faster, and can make
865 them bigger if we did partial redundancy elimination (when optimizing
866 for space, we use a classic gcse algorithm instead of partial
867 redundancy algorithms). */
870 max_gcse_regno
= max_reg_num ();
872 changed
|= one_code_hoisting_pass ();
875 if (max_pass_bytes
< bytes_used
)
876 max_pass_bytes
= bytes_used
;
881 fprintf (file
, "\n");
885 obstack_free (&gcse_obstack
, gcse_obstack_bottom
);
889 /* Do one last pass of copy propagation, including cprop into
890 conditional jumps. */
892 max_gcse_regno
= max_reg_num ();
894 /* This time, go ahead and allow cprop to alter jumps. */
895 one_cprop_pass (pass
+ 1, 1, 0);
900 fprintf (file
, "GCSE of %s: %d basic blocks, ",
901 current_function_name
, n_basic_blocks
);
902 fprintf (file
, "%d pass%s, %d bytes\n\n",
903 pass
, pass
> 1 ? "es" : "", max_pass_bytes
);
906 obstack_free (&gcse_obstack
, NULL
);
908 /* We are finished with alias. */
909 end_alias_analysis ();
910 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
912 /* Store motion disabled until it is fixed. */
913 if (0 && !optimize_size
&& flag_gcse_sm
)
915 /* Record where pseudo-registers are set. */
916 return run_jump_opt_after_gcse
;
919 /* Misc. utilities. */
921 /* Compute which modes support reg/reg copy operations. */
927 #ifndef AVOID_CCMODE_COPIES
930 memset (can_copy_p
, 0, NUM_MACHINE_MODES
);
933 for (i
= 0; i
< NUM_MACHINE_MODES
; i
++)
934 if (GET_MODE_CLASS (i
) == MODE_CC
)
936 #ifdef AVOID_CCMODE_COPIES
939 reg
= gen_rtx_REG ((enum machine_mode
) i
, LAST_VIRTUAL_REGISTER
+ 1);
940 insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, reg
));
941 if (recog (PATTERN (insn
), insn
, NULL
) >= 0)
951 /* Cover function to xmalloc to record bytes allocated. */
958 return xmalloc (size
);
961 /* Cover function to xrealloc.
962 We don't record the additional size since we don't know it.
963 It won't affect memory usage stats much anyway. */
970 return xrealloc (ptr
, size
);
973 /* Cover function to obstack_alloc. */
980 return (char *) obstack_alloc (&gcse_obstack
, size
);
983 /* Allocate memory for the cuid mapping array,
984 and reg/memory set tracking tables.
986 This is called at the start of each pass. */
995 /* Find the largest UID and create a mapping from UIDs to CUIDs.
996 CUIDs are like UIDs except they increase monotonically, have no gaps,
997 and only apply to real insns. */
999 max_uid
= get_max_uid ();
1000 n
= (max_uid
+ 1) * sizeof (int);
1001 uid_cuid
= (int *) gmalloc (n
);
1002 memset ((char *) uid_cuid
, 0, n
);
1003 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
1006 uid_cuid
[INSN_UID (insn
)] = i
++;
1008 uid_cuid
[INSN_UID (insn
)] = i
;
1011 /* Create a table mapping cuids to insns. */
1014 n
= (max_cuid
+ 1) * sizeof (rtx
);
1015 cuid_insn
= (rtx
*) gmalloc (n
);
1016 memset ((char *) cuid_insn
, 0, n
);
1017 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
1019 CUID_INSN (i
++) = insn
;
1021 /* Allocate vars to track sets of regs. */
1022 reg_set_bitmap
= BITMAP_XMALLOC ();
1024 /* Allocate vars to track sets of regs, memory per block. */
1025 reg_set_in_block
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
,
1027 /* Allocate array to keep a list of insns which modify memory in each
1029 modify_mem_list
= (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
1030 canon_modify_mem_list
= (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
1031 memset ((char *) modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
1032 memset ((char *) canon_modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
1033 modify_mem_list_set
= BITMAP_XMALLOC ();
1034 canon_modify_mem_list_set
= BITMAP_XMALLOC ();
1037 /* Free memory allocated by alloc_gcse_mem. */
1045 BITMAP_XFREE (reg_set_bitmap
);
1047 sbitmap_vector_free (reg_set_in_block
);
1048 free_modify_mem_tables ();
1049 BITMAP_XFREE (modify_mem_list_set
);
1050 BITMAP_XFREE (canon_modify_mem_list_set
);
1053 /* Many of the global optimization algorithms work by solving dataflow
1054 equations for various expressions. Initially, some local value is
1055 computed for each expression in each block. Then, the values across the
1056 various blocks are combined (by following flow graph edges) to arrive at
1057 global values. Conceptually, each set of equations is independent. We
1058 may therefore solve all the equations in parallel, solve them one at a
1059 time, or pick any intermediate approach.
1061 When you're going to need N two-dimensional bitmaps, each X (say, the
1062 number of blocks) by Y (say, the number of expressions), call this
1063 function. It's not important what X and Y represent; only that Y
1064 correspond to the things that can be done in parallel. This function will
1065 return an appropriate chunking factor C; you should solve C sets of
1066 equations in parallel. By going through this function, we can easily
1067 trade space against time; by solving fewer equations in parallel we use
1071 get_bitmap_width (n
, x
, y
)
1076 /* It's not really worth figuring out *exactly* how much memory will
1077 be used by a particular choice. The important thing is to get
1078 something approximately right. */
1079 size_t max_bitmap_memory
= 10 * 1024 * 1024;
1081 /* The number of bytes we'd use for a single column of minimum
1083 size_t column_size
= n
* x
* sizeof (SBITMAP_ELT_TYPE
);
1085 /* Often, it's reasonable just to solve all the equations in
1087 if (column_size
* SBITMAP_SET_SIZE (y
) <= max_bitmap_memory
)
1090 /* Otherwise, pick the largest width we can, without going over the
1092 return SBITMAP_ELT_BITS
* ((max_bitmap_memory
+ column_size
- 1)
1096 /* Compute the local properties of each recorded expression.
1098 Local properties are those that are defined by the block, irrespective of
1101 An expression is transparent in a block if its operands are not modified
1104 An expression is computed (locally available) in a block if it is computed
1105 at least once and expression would contain the same value if the
1106 computation was moved to the end of the block.
1108 An expression is locally anticipatable in a block if it is computed at
1109 least once and expression would contain the same value if the computation
1110 was moved to the beginning of the block.
1112 We call this routine for cprop, pre and code hoisting. They all compute
1113 basically the same information and thus can easily share this code.
1115 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1116 properties. If NULL, then it is not necessary to compute or record that
1117 particular property.
1119 TABLE controls which hash table to look at. If it is set hash table,
1120 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1124 compute_local_properties (transp
, comp
, antloc
, table
)
1128 struct hash_table
*table
;
1132 /* Initialize any bitmaps that were passed in. */
1136 sbitmap_vector_zero (transp
, last_basic_block
);
1138 sbitmap_vector_ones (transp
, last_basic_block
);
1142 sbitmap_vector_zero (comp
, last_basic_block
);
1144 sbitmap_vector_zero (antloc
, last_basic_block
);
1146 for (i
= 0; i
< table
->size
; i
++)
1150 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1152 int indx
= expr
->bitmap_index
;
1155 /* The expression is transparent in this block if it is not killed.
1156 We start by assuming all are transparent [none are killed], and
1157 then reset the bits for those that are. */
1159 compute_transp (expr
->expr
, indx
, transp
, table
->set_p
);
1161 /* The occurrences recorded in antic_occr are exactly those that
1162 we want to set to nonzero in ANTLOC. */
1164 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
1166 SET_BIT (antloc
[BLOCK_NUM (occr
->insn
)], indx
);
1168 /* While we're scanning the table, this is a good place to
1170 occr
->deleted_p
= 0;
1173 /* The occurrences recorded in avail_occr are exactly those that
1174 we want to set to nonzero in COMP. */
1176 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
1178 SET_BIT (comp
[BLOCK_NUM (occr
->insn
)], indx
);
1180 /* While we're scanning the table, this is a good place to
1185 /* While we're scanning the table, this is a good place to
1187 expr
->reaching_reg
= 0;
1192 /* Register set information.
1194 `reg_set_table' records where each register is set or otherwise
1197 static struct obstack reg_set_obstack
;
1200 alloc_reg_set_mem (n_regs
)
1205 reg_set_table_size
= n_regs
+ REG_SET_TABLE_SLOP
;
1206 n
= reg_set_table_size
* sizeof (struct reg_set
*);
1207 reg_set_table
= (struct reg_set
**) gmalloc (n
);
1208 memset ((char *) reg_set_table
, 0, n
);
1210 gcc_obstack_init (®_set_obstack
);
1216 free (reg_set_table
);
1217 obstack_free (®_set_obstack
, NULL
);
1220 /* Record REGNO in the reg_set table. */
1223 record_one_set (regno
, insn
)
1227 /* Allocate a new reg_set element and link it onto the list. */
1228 struct reg_set
*new_reg_info
;
1230 /* If the table isn't big enough, enlarge it. */
1231 if (regno
>= reg_set_table_size
)
1233 int new_size
= regno
+ REG_SET_TABLE_SLOP
;
1236 = (struct reg_set
**) grealloc ((char *) reg_set_table
,
1237 new_size
* sizeof (struct reg_set
*));
1238 memset ((char *) (reg_set_table
+ reg_set_table_size
), 0,
1239 (new_size
- reg_set_table_size
) * sizeof (struct reg_set
*));
1240 reg_set_table_size
= new_size
;
1243 new_reg_info
= (struct reg_set
*) obstack_alloc (®_set_obstack
,
1244 sizeof (struct reg_set
));
1245 bytes_used
+= sizeof (struct reg_set
);
1246 new_reg_info
->insn
= insn
;
1247 new_reg_info
->next
= reg_set_table
[regno
];
1248 reg_set_table
[regno
] = new_reg_info
;
1251 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1252 an insn. The DATA is really the instruction in which the SET is
1256 record_set_info (dest
, setter
, data
)
1257 rtx dest
, setter ATTRIBUTE_UNUSED
;
1260 rtx record_set_insn
= (rtx
) data
;
1262 if (GET_CODE (dest
) == REG
&& REGNO (dest
) >= FIRST_PSEUDO_REGISTER
)
1263 record_one_set (REGNO (dest
), record_set_insn
);
1266 /* Scan the function and record each set of each pseudo-register.
1268 This is called once, at the start of the gcse pass. See the comments for
1269 `reg_set_table' for further documentation. */
1277 for (insn
= f
; insn
!= 0; insn
= NEXT_INSN (insn
))
1279 note_stores (PATTERN (insn
), record_set_info
, insn
);
1282 /* Hash table support. */
1284 struct reg_avail_info
1286 basic_block last_bb
;
1291 static struct reg_avail_info
*reg_avail_info
;
1292 static basic_block current_bb
;
1295 /* See whether X, the source of a set, is something we want to consider for
1298 static GTY(()) rtx test_insn
;
1303 int num_clobbers
= 0;
1306 switch (GET_CODE (x
))
1314 case CONSTANT_P_RTX
:
1321 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1322 if (general_operand (x
, GET_MODE (x
)))
1324 else if (GET_MODE (x
) == VOIDmode
)
1327 /* Otherwise, check if we can make a valid insn from it. First initialize
1328 our test insn if we haven't already. */
1332 = make_insn_raw (gen_rtx_SET (VOIDmode
,
1333 gen_rtx_REG (word_mode
,
1334 FIRST_PSEUDO_REGISTER
* 2),
1336 NEXT_INSN (test_insn
) = PREV_INSN (test_insn
) = 0;
1339 /* Now make an insn like the one we would make when GCSE'ing and see if
1341 PUT_MODE (SET_DEST (PATTERN (test_insn
)), GET_MODE (x
));
1342 SET_SRC (PATTERN (test_insn
)) = x
;
1343 return ((icode
= recog (PATTERN (test_insn
), test_insn
, &num_clobbers
)) >= 0
1344 && (num_clobbers
== 0 || ! added_clobbers_hard_reg_p (icode
)));
1347 /* Return nonzero if the operands of expression X are unchanged from the
1348 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1349 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1352 oprs_unchanged_p (x
, insn
, avail_p
)
1363 code
= GET_CODE (x
);
1368 struct reg_avail_info
*info
= ®_avail_info
[REGNO (x
)];
1370 if (info
->last_bb
!= current_bb
)
1373 return info
->last_set
< INSN_CUID (insn
);
1375 return info
->first_set
>= INSN_CUID (insn
);
1379 if (load_killed_in_block_p (current_bb
, INSN_CUID (insn
),
1383 return oprs_unchanged_p (XEXP (x
, 0), insn
, avail_p
);
1409 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1413 /* If we are about to do the last recursive call needed at this
1414 level, change it into iteration. This function is called enough
1417 return oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
);
1419 else if (! oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
))
1422 else if (fmt
[i
] == 'E')
1423 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1424 if (! oprs_unchanged_p (XVECEXP (x
, i
, j
), insn
, avail_p
))
1431 /* Used for communication between mems_conflict_for_gcse_p and
1432 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1433 conflict between two memory references. */
1434 static int gcse_mems_conflict_p
;
1436 /* Used for communication between mems_conflict_for_gcse_p and
1437 load_killed_in_block_p. A memory reference for a load instruction,
1438 mems_conflict_for_gcse_p will see if a memory store conflicts with
1439 this memory load. */
1440 static rtx gcse_mem_operand
;
1442 /* DEST is the output of an instruction. If it is a memory reference, and
1443 possibly conflicts with the load found in gcse_mem_operand, then set
1444 gcse_mems_conflict_p to a nonzero value. */
1447 mems_conflict_for_gcse_p (dest
, setter
, data
)
1448 rtx dest
, setter ATTRIBUTE_UNUSED
;
1449 void *data ATTRIBUTE_UNUSED
;
1451 while (GET_CODE (dest
) == SUBREG
1452 || GET_CODE (dest
) == ZERO_EXTRACT
1453 || GET_CODE (dest
) == SIGN_EXTRACT
1454 || GET_CODE (dest
) == STRICT_LOW_PART
)
1455 dest
= XEXP (dest
, 0);
1457 /* If DEST is not a MEM, then it will not conflict with the load. Note
1458 that function calls are assumed to clobber memory, but are handled
1460 if (GET_CODE (dest
) != MEM
)
1463 /* If we are setting a MEM in our list of specially recognized MEMs,
1464 don't mark as killed this time. */
1466 if (dest
== gcse_mem_operand
&& pre_ldst_mems
!= NULL
)
1468 if (!find_rtx_in_ldst (dest
))
1469 gcse_mems_conflict_p
= 1;
1473 if (true_dependence (dest
, GET_MODE (dest
), gcse_mem_operand
,
1475 gcse_mems_conflict_p
= 1;
1478 /* Return nonzero if the expression in X (a memory reference) is killed
1479 in block BB before or after the insn with the CUID in UID_LIMIT.
1480 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1483 To check the entire block, set UID_LIMIT to max_uid + 1 and
1487 load_killed_in_block_p (bb
, uid_limit
, x
, avail_p
)
1493 rtx list_entry
= modify_mem_list
[bb
->index
];
1497 /* Ignore entries in the list that do not apply. */
1499 && INSN_CUID (XEXP (list_entry
, 0)) < uid_limit
)
1501 && INSN_CUID (XEXP (list_entry
, 0)) > uid_limit
))
1503 list_entry
= XEXP (list_entry
, 1);
1507 setter
= XEXP (list_entry
, 0);
1509 /* If SETTER is a call everything is clobbered. Note that calls
1510 to pure functions are never put on the list, so we need not
1511 worry about them. */
1512 if (GET_CODE (setter
) == CALL_INSN
)
1515 /* SETTER must be an INSN of some kind that sets memory. Call
1516 note_stores to examine each hunk of memory that is modified.
1518 The note_stores interface is pretty limited, so we have to
1519 communicate via global variables. Yuk. */
1520 gcse_mem_operand
= x
;
1521 gcse_mems_conflict_p
= 0;
1522 note_stores (PATTERN (setter
), mems_conflict_for_gcse_p
, NULL
);
1523 if (gcse_mems_conflict_p
)
1525 list_entry
= XEXP (list_entry
, 1);
1530 /* Return nonzero if the operands of expression X are unchanged from
1531 the start of INSN's basic block up to but not including INSN. */
1534 oprs_anticipatable_p (x
, insn
)
1537 return oprs_unchanged_p (x
, insn
, 0);
1540 /* Return nonzero if the operands of expression X are unchanged from
1541 INSN to the end of INSN's basic block. */
1544 oprs_available_p (x
, insn
)
1547 return oprs_unchanged_p (x
, insn
, 1);
1550 /* Hash expression X.
1552 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1553 indicating if a volatile operand is found or if the expression contains
1554 something we don't want to insert in the table.
1556 ??? One might want to merge this with canon_hash. Later. */
1559 hash_expr (x
, mode
, do_not_record_p
, hash_table_size
)
1561 enum machine_mode mode
;
1562 int *do_not_record_p
;
1563 int hash_table_size
;
1567 *do_not_record_p
= 0;
1569 hash
= hash_expr_1 (x
, mode
, do_not_record_p
);
1570 return hash
% hash_table_size
;
1573 /* Hash a string. Just add its bytes up. */
1575 static inline unsigned
1580 const unsigned char *p
= (const unsigned char *) ps
;
1589 /* Subroutine of hash_expr to do the actual work. */
1592 hash_expr_1 (x
, mode
, do_not_record_p
)
1594 enum machine_mode mode
;
1595 int *do_not_record_p
;
1602 /* Used to turn recursion into iteration. We can't rely on GCC's
1603 tail-recursion elimination since we need to keep accumulating values
1610 code
= GET_CODE (x
);
1614 hash
+= ((unsigned int) REG
<< 7) + REGNO (x
);
1618 hash
+= (((unsigned int) CONST_INT
<< 7) + (unsigned int) mode
1619 + (unsigned int) INTVAL (x
));
1623 /* This is like the general case, except that it only counts
1624 the integers representing the constant. */
1625 hash
+= (unsigned int) code
+ (unsigned int) GET_MODE (x
);
1626 if (GET_MODE (x
) != VOIDmode
)
1627 for (i
= 2; i
< GET_RTX_LENGTH (CONST_DOUBLE
); i
++)
1628 hash
+= (unsigned int) XWINT (x
, i
);
1630 hash
+= ((unsigned int) CONST_DOUBLE_LOW (x
)
1631 + (unsigned int) CONST_DOUBLE_HIGH (x
));
1639 units
= CONST_VECTOR_NUNITS (x
);
1641 for (i
= 0; i
< units
; ++i
)
1643 elt
= CONST_VECTOR_ELT (x
, i
);
1644 hash
+= hash_expr_1 (elt
, GET_MODE (elt
), do_not_record_p
);
1650 /* Assume there is only one rtx object for any given label. */
1652 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1653 differences and differences between each stage's debugging dumps. */
1654 hash
+= (((unsigned int) LABEL_REF
<< 7)
1655 + CODE_LABEL_NUMBER (XEXP (x
, 0)));
1660 /* Don't hash on the symbol's address to avoid bootstrap differences.
1661 Different hash values may cause expressions to be recorded in
1662 different orders and thus different registers to be used in the
1663 final assembler. This also avoids differences in the dump files
1664 between various stages. */
1666 const unsigned char *p
= (const unsigned char *) XSTR (x
, 0);
1669 h
+= (h
<< 7) + *p
++; /* ??? revisit */
1671 hash
+= ((unsigned int) SYMBOL_REF
<< 7) + h
;
1676 if (MEM_VOLATILE_P (x
))
1678 *do_not_record_p
= 1;
1682 hash
+= (unsigned int) MEM
;
1683 /* We used alias set for hashing, but this is not good, since the alias
1684 set may differ in -fprofile-arcs and -fbranch-probabilities compilation
1685 causing the profiles to fail to match. */
1696 case UNSPEC_VOLATILE
:
1697 *do_not_record_p
= 1;
1701 if (MEM_VOLATILE_P (x
))
1703 *do_not_record_p
= 1;
1708 /* We don't want to take the filename and line into account. */
1709 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
)
1710 + hash_string_1 (ASM_OPERANDS_TEMPLATE (x
))
1711 + hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
))
1712 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x
);
1714 if (ASM_OPERANDS_INPUT_LENGTH (x
))
1716 for (i
= 1; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
1718 hash
+= (hash_expr_1 (ASM_OPERANDS_INPUT (x
, i
),
1719 GET_MODE (ASM_OPERANDS_INPUT (x
, i
)),
1721 + hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT
1725 hash
+= hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x
, 0));
1726 x
= ASM_OPERANDS_INPUT (x
, 0);
1727 mode
= GET_MODE (x
);
1737 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
);
1738 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1742 /* If we are about to do the last recursive call
1743 needed at this level, change it into iteration.
1744 This function is called enough to be worth it. */
1751 hash
+= hash_expr_1 (XEXP (x
, i
), 0, do_not_record_p
);
1752 if (*do_not_record_p
)
1756 else if (fmt
[i
] == 'E')
1757 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1759 hash
+= hash_expr_1 (XVECEXP (x
, i
, j
), 0, do_not_record_p
);
1760 if (*do_not_record_p
)
1764 else if (fmt
[i
] == 's')
1765 hash
+= hash_string_1 (XSTR (x
, i
));
1766 else if (fmt
[i
] == 'i')
1767 hash
+= (unsigned int) XINT (x
, i
);
1775 /* Hash a set of register REGNO.
1777 Sets are hashed on the register that is set. This simplifies the PRE copy
1780 ??? May need to make things more elaborate. Later, as necessary. */
1783 hash_set (regno
, hash_table_size
)
1785 int hash_table_size
;
1790 return hash
% hash_table_size
;
1793 /* Return nonzero if exp1 is equivalent to exp2.
1794 ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
1807 if (x
== 0 || y
== 0)
1810 code
= GET_CODE (x
);
1811 if (code
!= GET_CODE (y
))
1814 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
1815 if (GET_MODE (x
) != GET_MODE (y
))
1825 return INTVAL (x
) == INTVAL (y
);
1828 return XEXP (x
, 0) == XEXP (y
, 0);
1831 return XSTR (x
, 0) == XSTR (y
, 0);
1834 return REGNO (x
) == REGNO (y
);
1837 /* Can't merge two expressions in different alias sets, since we can
1838 decide that the expression is transparent in a block when it isn't,
1839 due to it being set with the different alias set. */
1840 if (MEM_ALIAS_SET (x
) != MEM_ALIAS_SET (y
))
1844 /* For commutative operations, check both orders. */
1852 return ((expr_equiv_p (XEXP (x
, 0), XEXP (y
, 0))
1853 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 1)))
1854 || (expr_equiv_p (XEXP (x
, 0), XEXP (y
, 1))
1855 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 0))));
1858 /* We don't use the generic code below because we want to
1859 disregard filename and line numbers. */
1861 /* A volatile asm isn't equivalent to any other. */
1862 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
1865 if (GET_MODE (x
) != GET_MODE (y
)
1866 || strcmp (ASM_OPERANDS_TEMPLATE (x
), ASM_OPERANDS_TEMPLATE (y
))
1867 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
),
1868 ASM_OPERANDS_OUTPUT_CONSTRAINT (y
))
1869 || ASM_OPERANDS_OUTPUT_IDX (x
) != ASM_OPERANDS_OUTPUT_IDX (y
)
1870 || ASM_OPERANDS_INPUT_LENGTH (x
) != ASM_OPERANDS_INPUT_LENGTH (y
))
1873 if (ASM_OPERANDS_INPUT_LENGTH (x
))
1875 for (i
= ASM_OPERANDS_INPUT_LENGTH (x
) - 1; i
>= 0; i
--)
1876 if (! expr_equiv_p (ASM_OPERANDS_INPUT (x
, i
),
1877 ASM_OPERANDS_INPUT (y
, i
))
1878 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x
, i
),
1879 ASM_OPERANDS_INPUT_CONSTRAINT (y
, i
)))
1889 /* Compare the elements. If any pair of corresponding elements
1890 fail to match, return 0 for the whole thing. */
1892 fmt
= GET_RTX_FORMAT (code
);
1893 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1898 if (! expr_equiv_p (XEXP (x
, i
), XEXP (y
, i
)))
1903 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1905 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1906 if (! expr_equiv_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
1911 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1916 if (XINT (x
, i
) != XINT (y
, i
))
1921 if (XWINT (x
, i
) != XWINT (y
, i
))
1936 /* Insert expression X in INSN in the hash TABLE.
1937 If it is already present, record it as the last occurrence in INSN's
1940 MODE is the mode of the value X is being stored into.
1941 It is only used if X is a CONST_INT.
1943 ANTIC_P is nonzero if X is an anticipatable expression.
1944 AVAIL_P is nonzero if X is an available expression. */
1947 insert_expr_in_table (x
, mode
, insn
, antic_p
, avail_p
, table
)
1949 enum machine_mode mode
;
1951 int antic_p
, avail_p
;
1952 struct hash_table
*table
;
1954 int found
, do_not_record_p
;
1956 struct expr
*cur_expr
, *last_expr
= NULL
;
1957 struct occr
*antic_occr
, *avail_occr
;
1958 struct occr
*last_occr
= NULL
;
1960 hash
= hash_expr (x
, mode
, &do_not_record_p
, table
->size
);
1962 /* Do not insert expression in table if it contains volatile operands,
1963 or if hash_expr determines the expression is something we don't want
1964 to or can't handle. */
1965 if (do_not_record_p
)
1968 cur_expr
= table
->table
[hash
];
1971 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1973 /* If the expression isn't found, save a pointer to the end of
1975 last_expr
= cur_expr
;
1976 cur_expr
= cur_expr
->next_same_hash
;
1981 cur_expr
= (struct expr
*) gcse_alloc (sizeof (struct expr
));
1982 bytes_used
+= sizeof (struct expr
);
1983 if (table
->table
[hash
] == NULL
)
1984 /* This is the first pattern that hashed to this index. */
1985 table
->table
[hash
] = cur_expr
;
1987 /* Add EXPR to end of this hash chain. */
1988 last_expr
->next_same_hash
= cur_expr
;
1990 /* Set the fields of the expr element. */
1992 cur_expr
->bitmap_index
= table
->n_elems
++;
1993 cur_expr
->next_same_hash
= NULL
;
1994 cur_expr
->antic_occr
= NULL
;
1995 cur_expr
->avail_occr
= NULL
;
1998 /* Now record the occurrence(s). */
2001 antic_occr
= cur_expr
->antic_occr
;
2003 /* Search for another occurrence in the same basic block. */
2004 while (antic_occr
&& BLOCK_NUM (antic_occr
->insn
) != BLOCK_NUM (insn
))
2006 /* If an occurrence isn't found, save a pointer to the end of
2008 last_occr
= antic_occr
;
2009 antic_occr
= antic_occr
->next
;
2013 /* Found another instance of the expression in the same basic block.
2014 Prefer the currently recorded one. We want the first one in the
2015 block and the block is scanned from start to end. */
2016 ; /* nothing to do */
2019 /* First occurrence of this expression in this basic block. */
2020 antic_occr
= (struct occr
*) gcse_alloc (sizeof (struct occr
));
2021 bytes_used
+= sizeof (struct occr
);
2022 /* First occurrence of this expression in any block? */
2023 if (cur_expr
->antic_occr
== NULL
)
2024 cur_expr
->antic_occr
= antic_occr
;
2026 last_occr
->next
= antic_occr
;
2028 antic_occr
->insn
= insn
;
2029 antic_occr
->next
= NULL
;
2035 avail_occr
= cur_expr
->avail_occr
;
2037 /* Search for another occurrence in the same basic block. */
2038 while (avail_occr
&& BLOCK_NUM (avail_occr
->insn
) != BLOCK_NUM (insn
))
2040 /* If an occurrence isn't found, save a pointer to the end of
2042 last_occr
= avail_occr
;
2043 avail_occr
= avail_occr
->next
;
2047 /* Found another instance of the expression in the same basic block.
2048 Prefer this occurrence to the currently recorded one. We want
2049 the last one in the block and the block is scanned from start
2051 avail_occr
->insn
= insn
;
2054 /* First occurrence of this expression in this basic block. */
2055 avail_occr
= (struct occr
*) gcse_alloc (sizeof (struct occr
));
2056 bytes_used
+= sizeof (struct occr
);
2058 /* First occurrence of this expression in any block? */
2059 if (cur_expr
->avail_occr
== NULL
)
2060 cur_expr
->avail_occr
= avail_occr
;
2062 last_occr
->next
= avail_occr
;
2064 avail_occr
->insn
= insn
;
2065 avail_occr
->next
= NULL
;
2070 /* Insert pattern X in INSN in the hash table.
2071 X is a SET of a reg to either another reg or a constant.
2072 If it is already present, record it as the last occurrence in INSN's
2076 insert_set_in_table (x
, insn
, table
)
2079 struct hash_table
*table
;
2083 struct expr
*cur_expr
, *last_expr
= NULL
;
2084 struct occr
*cur_occr
, *last_occr
= NULL
;
2086 if (GET_CODE (x
) != SET
2087 || GET_CODE (SET_DEST (x
)) != REG
)
2090 hash
= hash_set (REGNO (SET_DEST (x
)), table
->size
);
2092 cur_expr
= table
->table
[hash
];
2095 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
2097 /* If the expression isn't found, save a pointer to the end of
2099 last_expr
= cur_expr
;
2100 cur_expr
= cur_expr
->next_same_hash
;
2105 cur_expr
= (struct expr
*) gcse_alloc (sizeof (struct expr
));
2106 bytes_used
+= sizeof (struct expr
);
2107 if (table
->table
[hash
] == NULL
)
2108 /* This is the first pattern that hashed to this index. */
2109 table
->table
[hash
] = cur_expr
;
2111 /* Add EXPR to end of this hash chain. */
2112 last_expr
->next_same_hash
= cur_expr
;
2114 /* Set the fields of the expr element.
2115 We must copy X because it can be modified when copy propagation is
2116 performed on its operands. */
2117 cur_expr
->expr
= copy_rtx (x
);
2118 cur_expr
->bitmap_index
= table
->n_elems
++;
2119 cur_expr
->next_same_hash
= NULL
;
2120 cur_expr
->antic_occr
= NULL
;
2121 cur_expr
->avail_occr
= NULL
;
2124 /* Now record the occurrence. */
2125 cur_occr
= cur_expr
->avail_occr
;
2127 /* Search for another occurrence in the same basic block. */
2128 while (cur_occr
&& BLOCK_NUM (cur_occr
->insn
) != BLOCK_NUM (insn
))
2130 /* If an occurrence isn't found, save a pointer to the end of
2132 last_occr
= cur_occr
;
2133 cur_occr
= cur_occr
->next
;
2137 /* Found another instance of the expression in the same basic block.
2138 Prefer this occurrence to the currently recorded one. We want the
2139 last one in the block and the block is scanned from start to end. */
2140 cur_occr
->insn
= insn
;
2143 /* First occurrence of this expression in this basic block. */
2144 cur_occr
= (struct occr
*) gcse_alloc (sizeof (struct occr
));
2145 bytes_used
+= sizeof (struct occr
);
2147 /* First occurrence of this expression in any block? */
2148 if (cur_expr
->avail_occr
== NULL
)
2149 cur_expr
->avail_occr
= cur_occr
;
2151 last_occr
->next
= cur_occr
;
2153 cur_occr
->insn
= insn
;
2154 cur_occr
->next
= NULL
;
2158 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
2162 hash_scan_set (pat
, insn
, table
)
2164 struct hash_table
*table
;
2166 rtx src
= SET_SRC (pat
);
2167 rtx dest
= SET_DEST (pat
);
2170 if (GET_CODE (src
) == CALL
)
2171 hash_scan_call (src
, insn
, table
);
2173 else if (GET_CODE (dest
) == REG
)
2175 unsigned int regno
= REGNO (dest
);
2178 /* If this is a single set and we are doing constant propagation,
2179 see if a REG_NOTE shows this equivalent to a constant. */
2180 if (table
->set_p
&& (note
= find_reg_equal_equiv_note (insn
)) != 0
2181 && CONSTANT_P (XEXP (note
, 0)))
2182 src
= XEXP (note
, 0), pat
= gen_rtx_SET (VOIDmode
, dest
, src
);
2184 /* Only record sets of pseudo-regs in the hash table. */
2186 && regno
>= FIRST_PSEUDO_REGISTER
2187 /* Don't GCSE something if we can't do a reg/reg copy. */
2188 && can_copy_p
[GET_MODE (dest
)]
2189 /* GCSE commonly inserts instruction after the insn. We can't
2190 do that easily for EH_REGION notes so disable GCSE on these
2192 && !find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
2193 /* Is SET_SRC something we want to gcse? */
2194 && want_to_gcse_p (src
)
2195 /* Don't CSE a nop. */
2196 && ! set_noop_p (pat
)
2197 /* Don't GCSE if it has attached REG_EQUIV note.
2198 At this point this only function parameters should have
2199 REG_EQUIV notes and if the argument slot is used somewhere
2200 explicitly, it means address of parameter has been taken,
2201 so we should not extend the lifetime of the pseudo. */
2202 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
2203 || GET_CODE (XEXP (note
, 0)) != MEM
))
2205 /* An expression is not anticipatable if its operands are
2206 modified before this insn or if this is not the only SET in
2208 int antic_p
= oprs_anticipatable_p (src
, insn
) && single_set (insn
);
2209 /* An expression is not available if its operands are
2210 subsequently modified, including this insn. It's also not
2211 available if this is a branch, because we can't insert
2212 a set after the branch. */
2213 int avail_p
= (oprs_available_p (src
, insn
)
2214 && ! JUMP_P (insn
));
2216 insert_expr_in_table (src
, GET_MODE (dest
), insn
, antic_p
, avail_p
, table
);
2219 /* Record sets for constant/copy propagation. */
2220 else if (table
->set_p
2221 && regno
>= FIRST_PSEUDO_REGISTER
2222 && ((GET_CODE (src
) == REG
2223 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
2224 && can_copy_p
[GET_MODE (dest
)]
2225 && REGNO (src
) != regno
)
2226 || (CONSTANT_P (src
)
2227 && GET_CODE (src
) != CONSTANT_P_RTX
))
2228 /* A copy is not available if its src or dest is subsequently
2229 modified. Here we want to search from INSN+1 on, but
2230 oprs_available_p searches from INSN on. */
2231 && (insn
== BLOCK_END (BLOCK_NUM (insn
))
2232 || ((tmp
= next_nonnote_insn (insn
)) != NULL_RTX
2233 && oprs_available_p (pat
, tmp
))))
2234 insert_set_in_table (pat
, insn
, table
);
2239 hash_scan_clobber (x
, insn
, table
)
2240 rtx x ATTRIBUTE_UNUSED
, insn ATTRIBUTE_UNUSED
;
2241 struct hash_table
*table ATTRIBUTE_UNUSED
;
2243 /* Currently nothing to do. */
2247 hash_scan_call (x
, insn
, table
)
2248 rtx x ATTRIBUTE_UNUSED
, insn ATTRIBUTE_UNUSED
;
2249 struct hash_table
*table ATTRIBUTE_UNUSED
;
2251 /* Currently nothing to do. */
2254 /* Process INSN and add hash table entries as appropriate.
2256 Only available expressions that set a single pseudo-reg are recorded.
2258 Single sets in a PARALLEL could be handled, but it's an extra complication
2259 that isn't dealt with right now. The trick is handling the CLOBBERs that
2260 are also in the PARALLEL. Later.
2262 If SET_P is nonzero, this is for the assignment hash table,
2263 otherwise it is for the expression hash table.
2264 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
2265 not record any expressions. */
2268 hash_scan_insn (insn
, table
, in_libcall_block
)
2270 struct hash_table
*table
;
2271 int in_libcall_block
;
2273 rtx pat
= PATTERN (insn
);
2276 if (in_libcall_block
)
2279 /* Pick out the sets of INSN and for other forms of instructions record
2280 what's been modified. */
2282 if (GET_CODE (pat
) == SET
)
2283 hash_scan_set (pat
, insn
, table
);
2284 else if (GET_CODE (pat
) == PARALLEL
)
2285 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2287 rtx x
= XVECEXP (pat
, 0, i
);
2289 if (GET_CODE (x
) == SET
)
2290 hash_scan_set (x
, insn
, table
);
2291 else if (GET_CODE (x
) == CLOBBER
)
2292 hash_scan_clobber (x
, insn
, table
);
2293 else if (GET_CODE (x
) == CALL
)
2294 hash_scan_call (x
, insn
, table
);
2297 else if (GET_CODE (pat
) == CLOBBER
)
2298 hash_scan_clobber (pat
, insn
, table
);
2299 else if (GET_CODE (pat
) == CALL
)
2300 hash_scan_call (pat
, insn
, table
);
2304 dump_hash_table (file
, name
, table
)
2307 struct hash_table
*table
;
2310 /* Flattened out table, so it's printed in proper order. */
2311 struct expr
**flat_table
;
2312 unsigned int *hash_val
;
2316 = (struct expr
**) xcalloc (table
->n_elems
, sizeof (struct expr
*));
2317 hash_val
= (unsigned int *) xmalloc (table
->n_elems
* sizeof (unsigned int));
2319 for (i
= 0; i
< (int) table
->size
; i
++)
2320 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
2322 flat_table
[expr
->bitmap_index
] = expr
;
2323 hash_val
[expr
->bitmap_index
] = i
;
2326 fprintf (file
, "%s hash table (%d buckets, %d entries)\n",
2327 name
, table
->size
, table
->n_elems
);
2329 for (i
= 0; i
< (int) table
->n_elems
; i
++)
2330 if (flat_table
[i
] != 0)
2332 expr
= flat_table
[i
];
2333 fprintf (file
, "Index %d (hash value %d)\n ",
2334 expr
->bitmap_index
, hash_val
[i
]);
2335 print_rtl (file
, expr
->expr
);
2336 fprintf (file
, "\n");
2339 fprintf (file
, "\n");
2345 /* Record register first/last/block set information for REGNO in INSN.
2347 first_set records the first place in the block where the register
2348 is set and is used to compute "anticipatability".
2350 last_set records the last place in the block where the register
2351 is set and is used to compute "availability".
2353 last_bb records the block for which first_set and last_set are
2354 valid, as a quick test to invalidate them.
2356 reg_set_in_block records whether the register is set in the block
2357 and is used to compute "transparency". */
2360 record_last_reg_set_info (insn
, regno
)
2364 struct reg_avail_info
*info
= ®_avail_info
[regno
];
2365 int cuid
= INSN_CUID (insn
);
2367 info
->last_set
= cuid
;
2368 if (info
->last_bb
!= current_bb
)
2370 info
->last_bb
= current_bb
;
2371 info
->first_set
= cuid
;
2372 SET_BIT (reg_set_in_block
[current_bb
->index
], regno
);
2377 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
2378 Note we store a pair of elements in the list, so they have to be
2379 taken off pairwise. */
2382 canon_list_insert (dest
, unused1
, v_insn
)
2383 rtx dest ATTRIBUTE_UNUSED
;
2384 rtx unused1 ATTRIBUTE_UNUSED
;
2387 rtx dest_addr
, insn
;
2390 while (GET_CODE (dest
) == SUBREG
2391 || GET_CODE (dest
) == ZERO_EXTRACT
2392 || GET_CODE (dest
) == SIGN_EXTRACT
2393 || GET_CODE (dest
) == STRICT_LOW_PART
)
2394 dest
= XEXP (dest
, 0);
2396 /* If DEST is not a MEM, then it will not conflict with a load. Note
2397 that function calls are assumed to clobber memory, but are handled
2400 if (GET_CODE (dest
) != MEM
)
2403 dest_addr
= get_addr (XEXP (dest
, 0));
2404 dest_addr
= canon_rtx (dest_addr
);
2405 insn
= (rtx
) v_insn
;
2406 bb
= BLOCK_NUM (insn
);
2408 canon_modify_mem_list
[bb
] =
2409 alloc_EXPR_LIST (VOIDmode
, dest_addr
, canon_modify_mem_list
[bb
]);
2410 canon_modify_mem_list
[bb
] =
2411 alloc_EXPR_LIST (VOIDmode
, dest
, canon_modify_mem_list
[bb
]);
2412 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2415 /* Record memory modification information for INSN. We do not actually care
2416 about the memory location(s) that are set, or even how they are set (consider
2417 a CALL_INSN). We merely need to record which insns modify memory. */
2420 record_last_mem_set_info (insn
)
2423 int bb
= BLOCK_NUM (insn
);
2425 /* load_killed_in_block_p will handle the case of calls clobbering
2427 modify_mem_list
[bb
] = alloc_INSN_LIST (insn
, modify_mem_list
[bb
]);
2428 bitmap_set_bit (modify_mem_list_set
, bb
);
2430 if (GET_CODE (insn
) == CALL_INSN
)
2432 /* Note that traversals of this loop (other than for free-ing)
2433 will break after encountering a CALL_INSN. So, there's no
2434 need to insert a pair of items, as canon_list_insert does. */
2435 canon_modify_mem_list
[bb
] =
2436 alloc_INSN_LIST (insn
, canon_modify_mem_list
[bb
]);
2437 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2440 note_stores (PATTERN (insn
), canon_list_insert
, (void*) insn
);
2443 /* Called from compute_hash_table via note_stores to handle one
2444 SET or CLOBBER in an insn. DATA is really the instruction in which
2445 the SET is taking place. */
2448 record_last_set_info (dest
, setter
, data
)
2449 rtx dest
, setter ATTRIBUTE_UNUSED
;
2452 rtx last_set_insn
= (rtx
) data
;
2454 if (GET_CODE (dest
) == SUBREG
)
2455 dest
= SUBREG_REG (dest
);
2457 if (GET_CODE (dest
) == REG
)
2458 record_last_reg_set_info (last_set_insn
, REGNO (dest
));
2459 else if (GET_CODE (dest
) == MEM
2460 /* Ignore pushes, they clobber nothing. */
2461 && ! push_operand (dest
, GET_MODE (dest
)))
2462 record_last_mem_set_info (last_set_insn
);
2465 /* Top level function to create an expression or assignment hash table.
2467 Expression entries are placed in the hash table if
2468 - they are of the form (set (pseudo-reg) src),
2469 - src is something we want to perform GCSE on,
2470 - none of the operands are subsequently modified in the block
2472 Assignment entries are placed in the hash table if
2473 - they are of the form (set (pseudo-reg) src),
2474 - src is something we want to perform const/copy propagation on,
2475 - none of the operands or target are subsequently modified in the block
2477 Currently src must be a pseudo-reg or a const_int.
2479 TABLE is the table computed. */
2482 compute_hash_table_work (table
)
2483 struct hash_table
*table
;
2487 /* While we compute the hash table we also compute a bit array of which
2488 registers are set in which blocks.
2489 ??? This isn't needed during const/copy propagation, but it's cheap to
2491 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
2493 /* re-Cache any INSN_LIST nodes we have allocated. */
2494 clear_modify_mem_tables ();
2495 /* Some working arrays used to track first and last set in each block. */
2496 reg_avail_info
= (struct reg_avail_info
*)
2497 gmalloc (max_gcse_regno
* sizeof (struct reg_avail_info
));
2499 for (i
= 0; i
< max_gcse_regno
; ++i
)
2500 reg_avail_info
[i
].last_bb
= NULL
;
2502 FOR_EACH_BB (current_bb
)
2506 int in_libcall_block
;
2508 /* First pass over the instructions records information used to
2509 determine when registers and memory are first and last set.
2510 ??? hard-reg reg_set_in_block computation
2511 could be moved to compute_sets since they currently don't change. */
2513 for (insn
= current_bb
->head
;
2514 insn
&& insn
!= NEXT_INSN (current_bb
->end
);
2515 insn
= NEXT_INSN (insn
))
2517 if (! INSN_P (insn
))
2520 if (GET_CODE (insn
) == CALL_INSN
)
2522 bool clobbers_all
= false;
2523 #ifdef NON_SAVING_SETJMP
2524 if (NON_SAVING_SETJMP
2525 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
2526 clobbers_all
= true;
2529 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2531 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2532 record_last_reg_set_info (insn
, regno
);
2537 note_stores (PATTERN (insn
), record_last_set_info
, insn
);
2540 /* Insert implicit sets in the hash table. */
2542 && implicit_sets
[current_bb
->index
] != NULL_RTX
)
2543 hash_scan_set (implicit_sets
[current_bb
->index
],
2544 current_bb
->head
, table
);
2546 /* The next pass builds the hash table. */
2548 for (insn
= current_bb
->head
, in_libcall_block
= 0;
2549 insn
&& insn
!= NEXT_INSN (current_bb
->end
);
2550 insn
= NEXT_INSN (insn
))
2553 if (find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2554 in_libcall_block
= 1;
2555 else if (table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2556 in_libcall_block
= 0;
2557 hash_scan_insn (insn
, table
, in_libcall_block
);
2558 if (!table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2559 in_libcall_block
= 0;
2563 free (reg_avail_info
);
2564 reg_avail_info
= NULL
;
2567 /* Allocate space for the set/expr hash TABLE.
2568 N_INSNS is the number of instructions in the function.
2569 It is used to determine the number of buckets to use.
2570 SET_P determines whether set or expression table will
2574 alloc_hash_table (n_insns
, table
, set_p
)
2576 struct hash_table
*table
;
2581 table
->size
= n_insns
/ 4;
2582 if (table
->size
< 11)
2585 /* Attempt to maintain efficient use of hash table.
2586 Making it an odd number is simplest for now.
2587 ??? Later take some measurements. */
2589 n
= table
->size
* sizeof (struct expr
*);
2590 table
->table
= (struct expr
**) gmalloc (n
);
2591 table
->set_p
= set_p
;
2594 /* Free things allocated by alloc_hash_table. */
2597 free_hash_table (table
)
2598 struct hash_table
*table
;
2600 free (table
->table
);
2603 /* Compute the hash TABLE for doing copy/const propagation or
2604 expression hash table. */
2607 compute_hash_table (table
)
2608 struct hash_table
*table
;
2610 /* Initialize count of number of entries in hash table. */
2612 memset ((char *) table
->table
, 0,
2613 table
->size
* sizeof (struct expr
*));
2615 compute_hash_table_work (table
);
2618 /* Expression tracking support. */
2620 /* Lookup pattern PAT in the expression TABLE.
2621 The result is a pointer to the table entry, or NULL if not found. */
2623 static struct expr
*
2624 lookup_expr (pat
, table
)
2626 struct hash_table
*table
;
2628 int do_not_record_p
;
2629 unsigned int hash
= hash_expr (pat
, GET_MODE (pat
), &do_not_record_p
,
2633 if (do_not_record_p
)
2636 expr
= table
->table
[hash
];
2638 while (expr
&& ! expr_equiv_p (expr
->expr
, pat
))
2639 expr
= expr
->next_same_hash
;
2644 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2645 table entry, or NULL if not found. */
2647 static struct expr
*
2648 lookup_set (regno
, table
)
2650 struct hash_table
*table
;
2652 unsigned int hash
= hash_set (regno
, table
->size
);
2655 expr
= table
->table
[hash
];
2657 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
)
2658 expr
= expr
->next_same_hash
;
2663 /* Return the next entry for REGNO in list EXPR. */
2665 static struct expr
*
2666 next_set (regno
, expr
)
2671 expr
= expr
->next_same_hash
;
2672 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
);
2677 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2678 types may be mixed. */
2681 free_insn_expr_list_list (listp
)
2686 for (list
= *listp
; list
; list
= next
)
2688 next
= XEXP (list
, 1);
2689 if (GET_CODE (list
) == EXPR_LIST
)
2690 free_EXPR_LIST_node (list
);
2692 free_INSN_LIST_node (list
);
2698 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2700 clear_modify_mem_tables ()
2704 EXECUTE_IF_SET_IN_BITMAP
2705 (modify_mem_list_set
, 0, i
, free_INSN_LIST_list (modify_mem_list
+ i
));
2706 bitmap_clear (modify_mem_list_set
);
2708 EXECUTE_IF_SET_IN_BITMAP
2709 (canon_modify_mem_list_set
, 0, i
,
2710 free_insn_expr_list_list (canon_modify_mem_list
+ i
));
2711 bitmap_clear (canon_modify_mem_list_set
);
2714 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2717 free_modify_mem_tables ()
2719 clear_modify_mem_tables ();
2720 free (modify_mem_list
);
2721 free (canon_modify_mem_list
);
2722 modify_mem_list
= 0;
2723 canon_modify_mem_list
= 0;
2726 /* Reset tables used to keep track of what's still available [since the
2727 start of the block]. */
2730 reset_opr_set_tables ()
2732 /* Maintain a bitmap of which regs have been set since beginning of
2734 CLEAR_REG_SET (reg_set_bitmap
);
2736 /* Also keep a record of the last instruction to modify memory.
2737 For now this is very trivial, we only record whether any memory
2738 location has been modified. */
2739 clear_modify_mem_tables ();
2742 /* Return nonzero if the operands of X are not set before INSN in
2743 INSN's basic block. */
2746 oprs_not_set_p (x
, insn
)
2756 code
= GET_CODE (x
);
2772 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn
),
2773 INSN_CUID (insn
), x
, 0))
2776 return oprs_not_set_p (XEXP (x
, 0), insn
);
2779 return ! REGNO_REG_SET_P (reg_set_bitmap
, REGNO (x
));
2785 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2789 /* If we are about to do the last recursive call
2790 needed at this level, change it into iteration.
2791 This function is called enough to be worth it. */
2793 return oprs_not_set_p (XEXP (x
, i
), insn
);
2795 if (! oprs_not_set_p (XEXP (x
, i
), insn
))
2798 else if (fmt
[i
] == 'E')
2799 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2800 if (! oprs_not_set_p (XVECEXP (x
, i
, j
), insn
))
2807 /* Mark things set by a CALL. */
2813 if (! CONST_OR_PURE_CALL_P (insn
))
2814 record_last_mem_set_info (insn
);
2817 /* Mark things set by a SET. */
2820 mark_set (pat
, insn
)
2823 rtx dest
= SET_DEST (pat
);
2825 while (GET_CODE (dest
) == SUBREG
2826 || GET_CODE (dest
) == ZERO_EXTRACT
2827 || GET_CODE (dest
) == SIGN_EXTRACT
2828 || GET_CODE (dest
) == STRICT_LOW_PART
)
2829 dest
= XEXP (dest
, 0);
2831 if (GET_CODE (dest
) == REG
)
2832 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (dest
));
2833 else if (GET_CODE (dest
) == MEM
)
2834 record_last_mem_set_info (insn
);
2836 if (GET_CODE (SET_SRC (pat
)) == CALL
)
2840 /* Record things set by a CLOBBER. */
2843 mark_clobber (pat
, insn
)
2846 rtx clob
= XEXP (pat
, 0);
2848 while (GET_CODE (clob
) == SUBREG
|| GET_CODE (clob
) == STRICT_LOW_PART
)
2849 clob
= XEXP (clob
, 0);
2851 if (GET_CODE (clob
) == REG
)
2852 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (clob
));
2854 record_last_mem_set_info (insn
);
2857 /* Record things set by INSN.
2858 This data is used by oprs_not_set_p. */
2861 mark_oprs_set (insn
)
2864 rtx pat
= PATTERN (insn
);
2867 if (GET_CODE (pat
) == SET
)
2868 mark_set (pat
, insn
);
2869 else if (GET_CODE (pat
) == PARALLEL
)
2870 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2872 rtx x
= XVECEXP (pat
, 0, i
);
2874 if (GET_CODE (x
) == SET
)
2876 else if (GET_CODE (x
) == CLOBBER
)
2877 mark_clobber (x
, insn
);
2878 else if (GET_CODE (x
) == CALL
)
2882 else if (GET_CODE (pat
) == CLOBBER
)
2883 mark_clobber (pat
, insn
);
2884 else if (GET_CODE (pat
) == CALL
)
2889 /* Classic GCSE reaching definition support. */
2891 /* Allocate reaching def variables. */
2894 alloc_rd_mem (n_blocks
, n_insns
)
2895 int n_blocks
, n_insns
;
2897 rd_kill
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2898 sbitmap_vector_zero (rd_kill
, n_blocks
);
2900 rd_gen
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2901 sbitmap_vector_zero (rd_gen
, n_blocks
);
2903 reaching_defs
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2904 sbitmap_vector_zero (reaching_defs
, n_blocks
);
2906 rd_out
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2907 sbitmap_vector_zero (rd_out
, n_blocks
);
2910 /* Free reaching def variables. */
2915 sbitmap_vector_free (rd_kill
);
2916 sbitmap_vector_free (rd_gen
);
2917 sbitmap_vector_free (reaching_defs
);
2918 sbitmap_vector_free (rd_out
);
2921 /* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
2924 handle_rd_kill_set (insn
, regno
, bb
)
2929 struct reg_set
*this_reg
;
2931 for (this_reg
= reg_set_table
[regno
]; this_reg
; this_reg
= this_reg
->next
)
2932 if (BLOCK_NUM (this_reg
->insn
) != BLOCK_NUM (insn
))
2933 SET_BIT (rd_kill
[bb
->index
], INSN_CUID (this_reg
->insn
));
2936 /* Compute the set of kill's for reaching definitions. */
2947 For each set bit in `gen' of the block (i.e each insn which
2948 generates a definition in the block)
2949 Call the reg set by the insn corresponding to that bit regx
2950 Look at the linked list starting at reg_set_table[regx]
2951 For each setting of regx in the linked list, which is not in
2953 Set the bit in `kill' corresponding to that insn. */
2955 for (cuid
= 0; cuid
< max_cuid
; cuid
++)
2956 if (TEST_BIT (rd_gen
[bb
->index
], cuid
))
2958 rtx insn
= CUID_INSN (cuid
);
2959 rtx pat
= PATTERN (insn
);
2961 if (GET_CODE (insn
) == CALL_INSN
)
2963 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2964 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2965 handle_rd_kill_set (insn
, regno
, bb
);
2968 if (GET_CODE (pat
) == PARALLEL
)
2970 for (i
= XVECLEN (pat
, 0) - 1; i
>= 0; i
--)
2972 enum rtx_code code
= GET_CODE (XVECEXP (pat
, 0, i
));
2974 if ((code
== SET
|| code
== CLOBBER
)
2975 && GET_CODE (XEXP (XVECEXP (pat
, 0, i
), 0)) == REG
)
2976 handle_rd_kill_set (insn
,
2977 REGNO (XEXP (XVECEXP (pat
, 0, i
), 0)),
2981 else if (GET_CODE (pat
) == SET
&& GET_CODE (SET_DEST (pat
)) == REG
)
2982 /* Each setting of this register outside of this block
2983 must be marked in the set of kills in this block. */
2984 handle_rd_kill_set (insn
, REGNO (SET_DEST (pat
)), bb
);
2988 /* Compute the reaching definitions as in
2989 Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
2990 Chapter 10. It is the same algorithm as used for computing available
2991 expressions but applied to the gens and kills of reaching definitions. */
2996 int changed
, passes
;
3000 sbitmap_copy (rd_out
[bb
->index
] /*dst*/, rd_gen
[bb
->index
] /*src*/);
3009 sbitmap_union_of_preds (reaching_defs
[bb
->index
], rd_out
, bb
->index
);
3010 changed
|= sbitmap_union_of_diff_cg (rd_out
[bb
->index
], rd_gen
[bb
->index
],
3011 reaching_defs
[bb
->index
], rd_kill
[bb
->index
]);
3017 fprintf (gcse_file
, "reaching def computation: %d passes\n", passes
);
3020 /* Classic GCSE available expression support. */
3022 /* Allocate memory for available expression computation. */
3025 alloc_avail_expr_mem (n_blocks
, n_exprs
)
3026 int n_blocks
, n_exprs
;
3028 ae_kill
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3029 sbitmap_vector_zero (ae_kill
, n_blocks
);
3031 ae_gen
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3032 sbitmap_vector_zero (ae_gen
, n_blocks
);
3034 ae_in
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3035 sbitmap_vector_zero (ae_in
, n_blocks
);
3037 ae_out
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3038 sbitmap_vector_zero (ae_out
, n_blocks
);
3042 free_avail_expr_mem ()
3044 sbitmap_vector_free (ae_kill
);
3045 sbitmap_vector_free (ae_gen
);
3046 sbitmap_vector_free (ae_in
);
3047 sbitmap_vector_free (ae_out
);
3050 /* Compute the set of available expressions generated in each basic block. */
3053 compute_ae_gen (expr_hash_table
)
3054 struct hash_table
*expr_hash_table
;
3060 /* For each recorded occurrence of each expression, set ae_gen[bb][expr].
3061 This is all we have to do because an expression is not recorded if it
3062 is not available, and the only expressions we want to work with are the
3063 ones that are recorded. */
3064 for (i
= 0; i
< expr_hash_table
->size
; i
++)
3065 for (expr
= expr_hash_table
->table
[i
]; expr
!= 0; expr
= expr
->next_same_hash
)
3066 for (occr
= expr
->avail_occr
; occr
!= 0; occr
= occr
->next
)
3067 SET_BIT (ae_gen
[BLOCK_NUM (occr
->insn
)], expr
->bitmap_index
);
3070 /* Return nonzero if expression X is killed in BB. */
3073 expr_killed_p (x
, bb
)
3084 code
= GET_CODE (x
);
3088 return TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
));
3091 if (load_killed_in_block_p (bb
, get_max_uid () + 1, x
, 0))
3094 return expr_killed_p (XEXP (x
, 0), bb
);
3112 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3116 /* If we are about to do the last recursive call
3117 needed at this level, change it into iteration.
3118 This function is called enough to be worth it. */
3120 return expr_killed_p (XEXP (x
, i
), bb
);
3121 else if (expr_killed_p (XEXP (x
, i
), bb
))
3124 else if (fmt
[i
] == 'E')
3125 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3126 if (expr_killed_p (XVECEXP (x
, i
, j
), bb
))
3133 /* Compute the set of available expressions killed in each basic block. */
3136 compute_ae_kill (ae_gen
, ae_kill
, expr_hash_table
)
3137 sbitmap
*ae_gen
, *ae_kill
;
3138 struct hash_table
*expr_hash_table
;
3145 for (i
= 0; i
< expr_hash_table
->size
; i
++)
3146 for (expr
= expr_hash_table
->table
[i
]; expr
; expr
= expr
->next_same_hash
)
3148 /* Skip EXPR if generated in this block. */
3149 if (TEST_BIT (ae_gen
[bb
->index
], expr
->bitmap_index
))
3152 if (expr_killed_p (expr
->expr
, bb
))
3153 SET_BIT (ae_kill
[bb
->index
], expr
->bitmap_index
);
3157 /* Actually perform the Classic GCSE optimizations. */
3159 /* Return nonzero if occurrence OCCR of expression EXPR reaches block BB.
3161 CHECK_SELF_LOOP is nonzero if we should consider a block reaching itself
3162 as a positive reach. We want to do this when there are two computations
3163 of the expression in the block.
3165 VISITED is a pointer to a working buffer for tracking which BB's have
3166 been visited. It is NULL for the top-level call.
3168 We treat reaching expressions that go through blocks containing the same
3169 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3170 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3171 2 as not reaching. The intent is to improve the probability of finding
3172 only one reaching expression and to reduce register lifetimes by picking
3173 the closest such expression. */
3176 expr_reaches_here_p_work (occr
, expr
, bb
, check_self_loop
, visited
)
3180 int check_self_loop
;
3185 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
3187 basic_block pred_bb
= pred
->src
;
3189 if (visited
[pred_bb
->index
])
3190 /* This predecessor has already been visited. Nothing to do. */
3192 else if (pred_bb
== bb
)
3194 /* BB loops on itself. */
3196 && TEST_BIT (ae_gen
[pred_bb
->index
], expr
->bitmap_index
)
3197 && BLOCK_NUM (occr
->insn
) == pred_bb
->index
)
3200 visited
[pred_bb
->index
] = 1;
3203 /* Ignore this predecessor if it kills the expression. */
3204 else if (TEST_BIT (ae_kill
[pred_bb
->index
], expr
->bitmap_index
))
3205 visited
[pred_bb
->index
] = 1;
3207 /* Does this predecessor generate this expression? */
3208 else if (TEST_BIT (ae_gen
[pred_bb
->index
], expr
->bitmap_index
))
3210 /* Is this the occurrence we're looking for?
3211 Note that there's only one generating occurrence per block
3212 so we just need to check the block number. */
3213 if (BLOCK_NUM (occr
->insn
) == pred_bb
->index
)
3216 visited
[pred_bb
->index
] = 1;
3219 /* Neither gen nor kill. */
3222 visited
[pred_bb
->index
] = 1;
3223 if (expr_reaches_here_p_work (occr
, expr
, pred_bb
, check_self_loop
,
3230 /* All paths have been checked. */
3234 /* This wrapper for expr_reaches_here_p_work() is to ensure that any
3235 memory allocated for that function is returned. */
3238 expr_reaches_here_p (occr
, expr
, bb
, check_self_loop
)
3242 int check_self_loop
;
3245 char *visited
= (char *) xcalloc (last_basic_block
, 1);
3247 rval
= expr_reaches_here_p_work (occr
, expr
, bb
, check_self_loop
, visited
);
3253 /* Return the instruction that computes EXPR that reaches INSN's basic block.
3254 If there is more than one such instruction, return NULL.
3256 Called only by handle_avail_expr. */
3259 computing_insn (expr
, insn
)
3263 basic_block bb
= BLOCK_FOR_INSN (insn
);
3265 if (expr
->avail_occr
->next
== NULL
)
3267 if (BLOCK_FOR_INSN (expr
->avail_occr
->insn
) == bb
)
3268 /* The available expression is actually itself
3269 (i.e. a loop in the flow graph) so do nothing. */
3272 /* (FIXME) Case that we found a pattern that was created by
3273 a substitution that took place. */
3274 return expr
->avail_occr
->insn
;
3278 /* Pattern is computed more than once.
3279 Search backwards from this insn to see how many of these
3280 computations actually reach this insn. */
3282 rtx insn_computes_expr
= NULL
;
3285 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
3287 if (BLOCK_FOR_INSN (occr
->insn
) == bb
)
3289 /* The expression is generated in this block.
3290 The only time we care about this is when the expression
3291 is generated later in the block [and thus there's a loop].
3292 We let the normal cse pass handle the other cases. */
3293 if (INSN_CUID (insn
) < INSN_CUID (occr
->insn
)
3294 && expr_reaches_here_p (occr
, expr
, bb
, 1))
3300 insn_computes_expr
= occr
->insn
;
3303 else if (expr_reaches_here_p (occr
, expr
, bb
, 0))
3309 insn_computes_expr
= occr
->insn
;
3313 if (insn_computes_expr
== NULL
)
3316 return insn_computes_expr
;
3320 /* Return nonzero if the definition in DEF_INSN can reach INSN.
3321 Only called by can_disregard_other_sets. */
3324 def_reaches_here_p (insn
, def_insn
)
3329 if (TEST_BIT (reaching_defs
[BLOCK_NUM (insn
)], INSN_CUID (def_insn
)))
3332 if (BLOCK_NUM (insn
) == BLOCK_NUM (def_insn
))
3334 if (INSN_CUID (def_insn
) < INSN_CUID (insn
))
3336 if (GET_CODE (PATTERN (def_insn
)) == PARALLEL
)
3338 else if (GET_CODE (PATTERN (def_insn
)) == CLOBBER
)
3339 reg
= XEXP (PATTERN (def_insn
), 0);
3340 else if (GET_CODE (PATTERN (def_insn
)) == SET
)
3341 reg
= SET_DEST (PATTERN (def_insn
));
3345 return ! reg_set_between_p (reg
, NEXT_INSN (def_insn
), insn
);
3354 /* Return nonzero if *ADDR_THIS_REG can only have one value at INSN. The
3355 value returned is the number of definitions that reach INSN. Returning a
3356 value of zero means that [maybe] more than one definition reaches INSN and
3357 the caller can't perform whatever optimization it is trying. i.e. it is
3358 always safe to return zero. */
3361 can_disregard_other_sets (addr_this_reg
, insn
, for_combine
)
3362 struct reg_set
**addr_this_reg
;
3366 int number_of_reaching_defs
= 0;
3367 struct reg_set
*this_reg
;
3369 for (this_reg
= *addr_this_reg
; this_reg
!= 0; this_reg
= this_reg
->next
)
3370 if (def_reaches_here_p (insn
, this_reg
->insn
))
3372 number_of_reaching_defs
++;
3373 /* Ignore parallels for now. */
3374 if (GET_CODE (PATTERN (this_reg
->insn
)) == PARALLEL
)
3378 && (GET_CODE (PATTERN (this_reg
->insn
)) == CLOBBER
3379 || ! rtx_equal_p (SET_SRC (PATTERN (this_reg
->insn
)),
3380 SET_SRC (PATTERN (insn
)))))
3381 /* A setting of the reg to a different value reaches INSN. */
3384 if (number_of_reaching_defs
> 1)
3386 /* If in this setting the value the register is being set to is
3387 equal to the previous value the register was set to and this
3388 setting reaches the insn we are trying to do the substitution
3389 on then we are ok. */
3390 if (GET_CODE (PATTERN (this_reg
->insn
)) == CLOBBER
)
3392 else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg
->insn
)),
3393 SET_SRC (PATTERN (insn
))))
3397 *addr_this_reg
= this_reg
;
3400 return number_of_reaching_defs
;
3403 /* Expression computed by insn is available and the substitution is legal,
3404 so try to perform the substitution.
3406 The result is nonzero if any changes were made. */
3409 handle_avail_expr (insn
, expr
)
3413 rtx pat
, insn_computes_expr
, expr_set
;
3415 struct reg_set
*this_reg
;
3416 int found_setting
, use_src
;
3419 /* We only handle the case where one computation of the expression
3420 reaches this instruction. */
3421 insn_computes_expr
= computing_insn (expr
, insn
);
3422 if (insn_computes_expr
== NULL
)
3424 expr_set
= single_set (insn_computes_expr
);
3431 /* At this point we know only one computation of EXPR outside of this
3432 block reaches this insn. Now try to find a register that the
3433 expression is computed into. */
3434 if (GET_CODE (SET_SRC (expr_set
)) == REG
)
3436 /* This is the case when the available expression that reaches
3437 here has already been handled as an available expression. */
3438 unsigned int regnum_for_replacing
3439 = REGNO (SET_SRC (expr_set
));
3441 /* If the register was created by GCSE we can't use `reg_set_table',
3442 however we know it's set only once. */
3443 if (regnum_for_replacing
>= max_gcse_regno
3444 /* If the register the expression is computed into is set only once,
3445 or only one set reaches this insn, we can use it. */
3446 || (((this_reg
= reg_set_table
[regnum_for_replacing
]),
3447 this_reg
->next
== NULL
)
3448 || can_disregard_other_sets (&this_reg
, insn
, 0)))
3457 unsigned int regnum_for_replacing
3458 = REGNO (SET_DEST (expr_set
));
3460 /* This shouldn't happen. */
3461 if (regnum_for_replacing
>= max_gcse_regno
)
3464 this_reg
= reg_set_table
[regnum_for_replacing
];
3466 /* If the register the expression is computed into is set only once,
3467 or only one set reaches this insn, use it. */
3468 if (this_reg
->next
== NULL
3469 || can_disregard_other_sets (&this_reg
, insn
, 0))
3475 pat
= PATTERN (insn
);
3477 to
= SET_SRC (expr_set
);
3479 to
= SET_DEST (expr_set
);
3480 changed
= validate_change (insn
, &SET_SRC (pat
), to
, 0);
3482 /* We should be able to ignore the return code from validate_change but
3483 to play it safe we check. */
3487 if (gcse_file
!= NULL
)
3489 fprintf (gcse_file
, "GCSE: Replacing the source in insn %d with",
3491 fprintf (gcse_file
, " reg %d %s insn %d\n",
3492 REGNO (to
), use_src
? "from" : "set in",
3493 INSN_UID (insn_computes_expr
));
3498 /* The register that the expr is computed into is set more than once. */
3499 else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
3501 /* Insert an insn after insnx that copies the reg set in insnx
3502 into a new pseudo register call this new register REGN.
3503 From insnb until end of basic block or until REGB is set
3504 replace all uses of REGB with REGN. */
3507 to
= gen_reg_rtx (GET_MODE (SET_DEST (expr_set
)));
3509 /* Generate the new insn. */
3510 /* ??? If the change fails, we return 0, even though we created
3511 an insn. I think this is ok. */
3513 = emit_insn_after (gen_rtx_SET (VOIDmode
, to
,
3514 SET_DEST (expr_set
)),
3515 insn_computes_expr
);
3517 /* Keep register set table up to date. */
3518 record_one_set (REGNO (to
), new_insn
);
3520 gcse_create_count
++;
3521 if (gcse_file
!= NULL
)
3523 fprintf (gcse_file
, "GCSE: Creating insn %d to copy value of reg %d",
3524 INSN_UID (NEXT_INSN (insn_computes_expr
)),
3525 REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr
)))));
3526 fprintf (gcse_file
, ", computed in insn %d,\n",
3527 INSN_UID (insn_computes_expr
));
3528 fprintf (gcse_file
, " into newly allocated reg %d\n",
3532 pat
= PATTERN (insn
);
3534 /* Do register replacement for INSN. */
3535 changed
= validate_change (insn
, &SET_SRC (pat
),
3537 (NEXT_INSN (insn_computes_expr
))),
3540 /* We should be able to ignore the return code from validate_change but
3541 to play it safe we check. */
3545 if (gcse_file
!= NULL
)
3548 "GCSE: Replacing the source in insn %d with reg %d ",
3550 REGNO (SET_DEST (PATTERN (NEXT_INSN
3551 (insn_computes_expr
)))));
3552 fprintf (gcse_file
, "set in insn %d\n",
3553 INSN_UID (insn_computes_expr
));
3561 /* Perform classic GCSE. This is called by one_classic_gcse_pass after all
3562 the dataflow analysis has been done.
3564 The result is nonzero if a change was made. */
3573 /* Note we start at block 1. */
3575 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3579 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
3581 /* Reset tables used to keep track of what's still valid [since the
3582 start of the block]. */
3583 reset_opr_set_tables ();
3585 for (insn
= bb
->head
;
3586 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
3587 insn
= NEXT_INSN (insn
))
3589 /* Is insn of form (set (pseudo-reg) ...)? */
3590 if (GET_CODE (insn
) == INSN
3591 && GET_CODE (PATTERN (insn
)) == SET
3592 && GET_CODE (SET_DEST (PATTERN (insn
))) == REG
3593 && REGNO (SET_DEST (PATTERN (insn
))) >= FIRST_PSEUDO_REGISTER
)
3595 rtx pat
= PATTERN (insn
);
3596 rtx src
= SET_SRC (pat
);
3599 if (want_to_gcse_p (src
)
3600 /* Is the expression recorded? */
3601 && ((expr
= lookup_expr (src
, &expr_hash_table
)) != NULL
)
3602 /* Is the expression available [at the start of the
3604 && TEST_BIT (ae_in
[bb
->index
], expr
->bitmap_index
)
3605 /* Are the operands unchanged since the start of the
3607 && oprs_not_set_p (src
, insn
))
3608 changed
|= handle_avail_expr (insn
, expr
);
3611 /* Keep track of everything modified by this insn. */
3612 /* ??? Need to be careful w.r.t. mods done to INSN. */
3614 mark_oprs_set (insn
);
3621 /* Top level routine to perform one classic GCSE pass.
3623 Return nonzero if a change was made. */
3626 one_classic_gcse_pass (pass
)
3631 gcse_subst_count
= 0;
3632 gcse_create_count
= 0;
3634 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
3635 alloc_rd_mem (last_basic_block
, max_cuid
);
3636 compute_hash_table (&expr_hash_table
);
3638 dump_hash_table (gcse_file
, "Expression", &expr_hash_table
);
3640 if (expr_hash_table
.n_elems
> 0)
3644 alloc_avail_expr_mem (last_basic_block
, expr_hash_table
.n_elems
);
3645 compute_ae_gen (&expr_hash_table
);
3646 compute_ae_kill (ae_gen
, ae_kill
, &expr_hash_table
);
3647 compute_available (ae_gen
, ae_kill
, ae_out
, ae_in
);
3648 changed
= classic_gcse ();
3649 free_avail_expr_mem ();
3653 free_hash_table (&expr_hash_table
);
3657 fprintf (gcse_file
, "\n");
3658 fprintf (gcse_file
, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
3659 current_function_name
, pass
, bytes_used
, gcse_subst_count
);
3660 fprintf (gcse_file
, "%d insns created\n", gcse_create_count
);
3666 /* Compute copy/constant propagation working variables. */
3668 /* Local properties of assignments. */
3669 static sbitmap
*cprop_pavloc
;
3670 static sbitmap
*cprop_absaltered
;
3672 /* Global properties of assignments (computed from the local properties). */
3673 static sbitmap
*cprop_avin
;
3674 static sbitmap
*cprop_avout
;
3676 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
3677 basic blocks. N_SETS is the number of sets. */
3680 alloc_cprop_mem (n_blocks
, n_sets
)
3681 int n_blocks
, n_sets
;
3683 cprop_pavloc
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3684 cprop_absaltered
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3686 cprop_avin
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3687 cprop_avout
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3690 /* Free vars used by copy/const propagation. */
3695 sbitmap_vector_free (cprop_pavloc
);
3696 sbitmap_vector_free (cprop_absaltered
);
3697 sbitmap_vector_free (cprop_avin
);
3698 sbitmap_vector_free (cprop_avout
);
3701 /* For each block, compute whether X is transparent. X is either an
3702 expression or an assignment [though we don't care which, for this context
3703 an assignment is treated as an expression]. For each block where an
3704 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
3708 compute_transp (x
, indx
, bmap
, set_p
)
3720 /* repeat is used to turn tail-recursion into iteration since GCC
3721 can't do it when there's no return value. */
3727 code
= GET_CODE (x
);
3733 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
3736 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
3737 SET_BIT (bmap
[bb
->index
], indx
);
3741 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
3742 SET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
3747 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
3750 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
3751 RESET_BIT (bmap
[bb
->index
], indx
);
3755 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
3756 RESET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
3765 rtx list_entry
= canon_modify_mem_list
[bb
->index
];
3769 rtx dest
, dest_addr
;
3771 if (GET_CODE (XEXP (list_entry
, 0)) == CALL_INSN
)
3774 SET_BIT (bmap
[bb
->index
], indx
);
3776 RESET_BIT (bmap
[bb
->index
], indx
);
3779 /* LIST_ENTRY must be an INSN of some kind that sets memory.
3780 Examine each hunk of memory that is modified. */
3782 dest
= XEXP (list_entry
, 0);
3783 list_entry
= XEXP (list_entry
, 1);
3784 dest_addr
= XEXP (list_entry
, 0);
3786 if (canon_true_dependence (dest
, GET_MODE (dest
), dest_addr
,
3787 x
, rtx_addr_varies_p
))
3790 SET_BIT (bmap
[bb
->index
], indx
);
3792 RESET_BIT (bmap
[bb
->index
], indx
);
3795 list_entry
= XEXP (list_entry
, 1);
3818 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3822 /* If we are about to do the last recursive call
3823 needed at this level, change it into iteration.
3824 This function is called enough to be worth it. */
3831 compute_transp (XEXP (x
, i
), indx
, bmap
, set_p
);
3833 else if (fmt
[i
] == 'E')
3834 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3835 compute_transp (XVECEXP (x
, i
, j
), indx
, bmap
, set_p
);
3839 /* Top level routine to do the dataflow analysis needed by copy/const
3843 compute_cprop_data ()
3845 compute_local_properties (cprop_absaltered
, cprop_pavloc
, NULL
, &set_hash_table
);
3846 compute_available (cprop_pavloc
, cprop_absaltered
,
3847 cprop_avout
, cprop_avin
);
3850 /* Copy/constant propagation. */
3852 /* Maximum number of register uses in an insn that we handle. */
3855 /* Table of uses found in an insn.
3856 Allocated statically to avoid alloc/free complexity and overhead. */
3857 static struct reg_use reg_use_table
[MAX_USES
];
3859 /* Index into `reg_use_table' while building it. */
3860 static int reg_use_count
;
3862 /* Set up a list of register numbers used in INSN. The found uses are stored
3863 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
3864 and contains the number of uses in the table upon exit.
3866 ??? If a register appears multiple times we will record it multiple times.
3867 This doesn't hurt anything but it will slow things down. */
3870 find_used_regs (xptr
, data
)
3872 void *data ATTRIBUTE_UNUSED
;
3879 /* repeat is used to turn tail-recursion into iteration since GCC
3880 can't do it when there's no return value. */
3885 code
= GET_CODE (x
);
3888 if (reg_use_count
== MAX_USES
)
3891 reg_use_table
[reg_use_count
].reg_rtx
= x
;
3895 /* Recursively scan the operands of this expression. */
3897 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3901 /* If we are about to do the last recursive call
3902 needed at this level, change it into iteration.
3903 This function is called enough to be worth it. */
3910 find_used_regs (&XEXP (x
, i
), data
);
3912 else if (fmt
[i
] == 'E')
3913 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3914 find_used_regs (&XVECEXP (x
, i
, j
), data
);
3918 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
3919 Returns nonzero is successful. */
3922 try_replace_reg (from
, to
, insn
)
3925 rtx note
= find_reg_equal_equiv_note (insn
);
3928 rtx set
= single_set (insn
);
3930 validate_replace_src_group (from
, to
, insn
);
3931 if (num_changes_pending () && apply_change_group ())
3934 if (!success
&& set
&& reg_mentioned_p (from
, SET_SRC (set
)))
3936 /* If above failed and this is a single set, try to simplify the source of
3937 the set given our substitution. We could perhaps try this for multiple
3938 SETs, but it probably won't buy us anything. */
3939 src
= simplify_replace_rtx (SET_SRC (set
), from
, to
);
3941 if (!rtx_equal_p (src
, SET_SRC (set
))
3942 && validate_change (insn
, &SET_SRC (set
), src
, 0))
3945 /* If we've failed to do replacement, have a single SET, and don't already
3946 have a note, add a REG_EQUAL note to not lose information. */
3947 if (!success
&& note
== 0 && set
!= 0)
3948 note
= set_unique_reg_note (insn
, REG_EQUAL
, copy_rtx (src
));
3951 /* If there is already a NOTE, update the expression in it with our
3954 XEXP (note
, 0) = simplify_replace_rtx (XEXP (note
, 0), from
, to
);
3956 /* REG_EQUAL may get simplified into register.
3957 We don't allow that. Remove that note. This code ought
3958 not to happen, because previous code ought to synthesize
3959 reg-reg move, but be on the safe side. */
3960 if (note
&& REG_P (XEXP (note
, 0)))
3961 remove_note (insn
, note
);
3966 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
3967 NULL no such set is found. */
3969 static struct expr
*
3970 find_avail_set (regno
, insn
)
3974 /* SET1 contains the last set found that can be returned to the caller for
3975 use in a substitution. */
3976 struct expr
*set1
= 0;
3978 /* Loops are not possible here. To get a loop we would need two sets
3979 available at the start of the block containing INSN. ie we would
3980 need two sets like this available at the start of the block:
3982 (set (reg X) (reg Y))
3983 (set (reg Y) (reg X))
3985 This can not happen since the set of (reg Y) would have killed the
3986 set of (reg X) making it unavailable at the start of this block. */
3990 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
3992 /* Find a set that is available at the start of the block
3993 which contains INSN. */
3996 if (TEST_BIT (cprop_avin
[BLOCK_NUM (insn
)], set
->bitmap_index
))
3998 set
= next_set (regno
, set
);
4001 /* If no available set was found we've reached the end of the
4002 (possibly empty) copy chain. */
4006 if (GET_CODE (set
->expr
) != SET
)
4009 src
= SET_SRC (set
->expr
);
4011 /* We know the set is available.
4012 Now check that SRC is ANTLOC (i.e. none of the source operands
4013 have changed since the start of the block).
4015 If the source operand changed, we may still use it for the next
4016 iteration of this loop, but we may not use it for substitutions. */
4018 if (CONSTANT_P (src
) || oprs_not_set_p (src
, insn
))
4021 /* If the source of the set is anything except a register, then
4022 we have reached the end of the copy chain. */
4023 if (GET_CODE (src
) != REG
)
4026 /* Follow the copy chain, ie start another iteration of the loop
4027 and see if we have an available copy into SRC. */
4028 regno
= REGNO (src
);
4031 /* SET1 holds the last set that was available and anticipatable at
4036 /* Subroutine of cprop_insn that tries to propagate constants into
4037 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
4038 it is the instruction that immediately precedes JUMP, and must be a
4039 single SET of a register. FROM is what we will try to replace,
4040 SRC is the constant we will try to substitute for it. Returns nonzero
4041 if a change was made. */
4044 cprop_jump (bb
, setcc
, jump
, from
, src
)
4052 rtx set
= pc_set (jump
);
4054 /* First substitute in the INSN condition as the SET_SRC of the JUMP,
4055 then substitute that given values in this expanded JUMP. */
4057 && !modified_between_p (from
, setcc
, jump
)
4058 && !modified_between_p (src
, setcc
, jump
))
4060 rtx setcc_set
= single_set (setcc
);
4061 rtx note
= find_reg_equal_equiv_note (setcc
);
4062 /* Use REG_EQUAL note if available. */
4063 rtx setcc_set_src
= (note
== 0) ? SET_SRC (setcc_set
) : XEXP (note
, 0);
4065 new_set
= simplify_replace_rtx (SET_SRC (set
),
4066 SET_DEST (setcc_set
),
4072 /* If NEW_SET is simplified down to either a label or a no-op, we
4073 don't have to replace FROM with SRC, but we still have to either
4074 turn JUMP to an unconditional branch or remove the no-op. This
4075 can happen if JUMP is simplified using the REG_EQUAL note in
4077 if (GET_CODE (new_set
) == LABEL_REF
|| new_set
== pc_rtx
)
4081 new = simplify_replace_rtx (new_set
, from
, src
);
4083 /* If no simplification can be made, then try the next
4085 if (rtx_equal_p (new, new_set
) || rtx_equal_p (new, SET_SRC (set
)))
4089 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
4094 /* Ensure the value computed inside the jump insn to be equivalent
4095 to one computed by setcc. */
4097 && modified_in_p (new, setcc
))
4099 if (! validate_change (jump
, &SET_SRC (set
), new, 0))
4102 /* If this has turned into an unconditional jump,
4103 then put a barrier after it so that the unreachable
4104 code will be deleted. */
4105 if (GET_CODE (SET_SRC (set
)) == LABEL_REF
)
4106 emit_barrier_after (jump
);
4110 /* Delete the cc0 setter. */
4111 if (setcc
!= NULL
&& CC0_P (SET_DEST (single_set (setcc
))))
4112 delete_insn (setcc
);
4115 run_jump_opt_after_gcse
= 1;
4118 if (gcse_file
!= NULL
)
4121 "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
4122 REGNO (from
), INSN_UID (jump
));
4123 print_rtl (gcse_file
, src
);
4124 fprintf (gcse_file
, "\n");
4126 purge_dead_edges (bb
);
4132 constprop_register (insn
, from
, to
, alter_jumps
)
4140 /* Check for reg or cc0 setting instructions followed by
4141 conditional branch instructions first. */
4143 && (sset
= single_set (insn
)) != NULL
4145 && any_condjump_p (NEXT_INSN (insn
)) && onlyjump_p (NEXT_INSN (insn
)))
4147 rtx dest
= SET_DEST (sset
);
4148 if ((REG_P (dest
) || CC0_P (dest
))
4149 && cprop_jump (BLOCK_FOR_INSN (insn
), insn
, NEXT_INSN (insn
), from
, to
))
4153 /* Handle normal insns next. */
4154 if (GET_CODE (insn
) == INSN
4155 && try_replace_reg (from
, to
, insn
))
4158 /* Try to propagate a CONST_INT into a conditional jump.
4159 We're pretty specific about what we will handle in this
4160 code, we can extend this as necessary over time.
4162 Right now the insn in question must look like
4163 (set (pc) (if_then_else ...)) */
4164 else if (alter_jumps
&& any_condjump_p (insn
) && onlyjump_p (insn
))
4165 return cprop_jump (BLOCK_FOR_INSN (insn
), NULL
, insn
, from
, to
);
4169 /* Perform constant and copy propagation on INSN.
4170 The result is nonzero if a change was made. */
4173 cprop_insn (insn
, alter_jumps
)
4177 struct reg_use
*reg_used
;
4185 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4187 note
= find_reg_equal_equiv_note (insn
);
4189 /* We may win even when propagating constants into notes. */
4191 find_used_regs (&XEXP (note
, 0), NULL
);
4193 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
4194 reg_used
++, reg_use_count
--)
4196 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
4200 /* Ignore registers created by GCSE.
4201 We do this because ... */
4202 if (regno
>= max_gcse_regno
)
4205 /* If the register has already been set in this block, there's
4206 nothing we can do. */
4207 if (! oprs_not_set_p (reg_used
->reg_rtx
, insn
))
4210 /* Find an assignment that sets reg_used and is available
4211 at the start of the block. */
4212 set
= find_avail_set (regno
, insn
);
4217 /* ??? We might be able to handle PARALLELs. Later. */
4218 if (GET_CODE (pat
) != SET
)
4221 src
= SET_SRC (pat
);
4223 /* Constant propagation. */
4224 if (CONSTANT_P (src
))
4226 if (constprop_register (insn
, reg_used
->reg_rtx
, src
, alter_jumps
))
4230 if (gcse_file
!= NULL
)
4232 fprintf (gcse_file
, "GLOBAL CONST-PROP: Replacing reg %d in ", regno
);
4233 fprintf (gcse_file
, "insn %d with constant ", INSN_UID (insn
));
4234 print_rtl (gcse_file
, src
);
4235 fprintf (gcse_file
, "\n");
4239 else if (GET_CODE (src
) == REG
4240 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
4241 && REGNO (src
) != regno
)
4243 if (try_replace_reg (reg_used
->reg_rtx
, src
, insn
))
4247 if (gcse_file
!= NULL
)
4249 fprintf (gcse_file
, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
4250 regno
, INSN_UID (insn
));
4251 fprintf (gcse_file
, " with reg %d\n", REGNO (src
));
4254 /* The original insn setting reg_used may or may not now be
4255 deletable. We leave the deletion to flow. */
4256 /* FIXME: If it turns out that the insn isn't deletable,
4257 then we may have unnecessarily extended register lifetimes
4258 and made things worse. */
4266 /* Like find_used_regs, but avoid recording uses that appear in
4267 input-output contexts such as zero_extract or pre_dec. This
4268 restricts the cases we consider to those for which local cprop
4269 can legitimately make replacements. */
4272 local_cprop_find_used_regs (xptr
, data
)
4281 switch (GET_CODE (x
))
4285 case STRICT_LOW_PART
:
4294 /* Can only legitimately appear this early in the context of
4295 stack pushes for function arguments, but handle all of the
4296 codes nonetheless. */
4300 /* Setting a subreg of a register larger than word_mode leaves
4301 the non-written words unchanged. */
4302 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x
))) > BITS_PER_WORD
)
4310 find_used_regs (xptr
, data
);
4313 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4314 their REG_EQUAL notes need updating. */
4317 do_local_cprop (x
, insn
, alter_jumps
, libcall_sp
)
4323 rtx newreg
= NULL
, newcnst
= NULL
;
4325 /* Rule out USE instructions and ASM statements as we don't want to
4326 change the hard registers mentioned. */
4327 if (GET_CODE (x
) == REG
4328 && (REGNO (x
) >= FIRST_PSEUDO_REGISTER
4329 || (GET_CODE (PATTERN (insn
)) != USE
4330 && asm_noperands (PATTERN (insn
)) < 0)))
4332 cselib_val
*val
= cselib_lookup (x
, GET_MODE (x
), 0);
4333 struct elt_loc_list
*l
;
4337 for (l
= val
->locs
; l
; l
= l
->next
)
4339 rtx this_rtx
= l
->loc
;
4345 if (CONSTANT_P (this_rtx
)
4346 && GET_CODE (this_rtx
) != CONSTANT_P_RTX
)
4348 if (REG_P (this_rtx
) && REGNO (this_rtx
) >= FIRST_PSEUDO_REGISTER
4349 /* Don't copy propagate if it has attached REG_EQUIV note.
4350 At this point this only function parameters should have
4351 REG_EQUIV notes and if the argument slot is used somewhere
4352 explicitly, it means address of parameter has been taken,
4353 so we should not extend the lifetime of the pseudo. */
4354 && (!(note
= find_reg_note (l
->setting_insn
, REG_EQUIV
, NULL_RTX
))
4355 || GET_CODE (XEXP (note
, 0)) != MEM
))
4358 if (newcnst
&& constprop_register (insn
, x
, newcnst
, alter_jumps
))
4360 /* If we find a case where we can't fix the retval REG_EQUAL notes
4361 match the new register, we either have to abandon this replacement
4362 or fix delete_trivially_dead_insns to preserve the setting insn,
4363 or make it delete the REG_EUAQL note, and fix up all passes that
4364 require the REG_EQUAL note there. */
4365 if (!adjust_libcall_notes (x
, newcnst
, insn
, libcall_sp
))
4367 if (gcse_file
!= NULL
)
4369 fprintf (gcse_file
, "LOCAL CONST-PROP: Replacing reg %d in ",
4371 fprintf (gcse_file
, "insn %d with constant ",
4373 print_rtl (gcse_file
, newcnst
);
4374 fprintf (gcse_file
, "\n");
4379 else if (newreg
&& newreg
!= x
&& try_replace_reg (x
, newreg
, insn
))
4381 adjust_libcall_notes (x
, newreg
, insn
, libcall_sp
);
4382 if (gcse_file
!= NULL
)
4385 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
4386 REGNO (x
), INSN_UID (insn
));
4387 fprintf (gcse_file
, " with reg %d\n", REGNO (newreg
));
4396 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4397 their REG_EQUAL notes need updating to reflect that OLDREG has been
4398 replaced with NEWVAL in INSN. Return true if all substitutions could
4401 adjust_libcall_notes (oldreg
, newval
, insn
, libcall_sp
)
4402 rtx oldreg
, newval
, insn
, *libcall_sp
;
4406 while ((end
= *libcall_sp
++))
4408 rtx note
= find_reg_equal_equiv_note (end
);
4415 if (reg_set_between_p (newval
, PREV_INSN (insn
), end
))
4419 note
= find_reg_equal_equiv_note (end
);
4422 if (reg_mentioned_p (newval
, XEXP (note
, 0)))
4425 while ((end
= *libcall_sp
++));
4429 XEXP (note
, 0) = replace_rtx (XEXP (note
, 0), oldreg
, newval
);
4435 #define MAX_NESTED_LIBCALLS 9
4438 local_cprop_pass (alter_jumps
)
4442 struct reg_use
*reg_used
;
4443 rtx libcall_stack
[MAX_NESTED_LIBCALLS
+ 1], *libcall_sp
;
4444 bool changed
= false;
4447 libcall_sp
= &libcall_stack
[MAX_NESTED_LIBCALLS
];
4449 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4453 rtx note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
4457 if (libcall_sp
== libcall_stack
)
4459 *--libcall_sp
= XEXP (note
, 0);
4461 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
4464 note
= find_reg_equal_equiv_note (insn
);
4468 note_uses (&PATTERN (insn
), local_cprop_find_used_regs
, NULL
);
4470 local_cprop_find_used_regs (&XEXP (note
, 0), NULL
);
4472 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
4473 reg_used
++, reg_use_count
--)
4474 if (do_local_cprop (reg_used
->reg_rtx
, insn
, alter_jumps
,
4481 while (reg_use_count
);
4483 cselib_process_insn (insn
);
4486 /* Global analysis may get into infinite loops for unreachable blocks. */
4487 if (changed
&& alter_jumps
)
4489 delete_unreachable_blocks ();
4490 free_reg_set_mem ();
4491 alloc_reg_set_mem (max_reg_num ());
4492 compute_sets (get_insns ());
4496 /* Forward propagate copies. This includes copies and constants. Return
4497 nonzero if a change was made. */
4507 /* Note we start at block 1. */
4508 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
4510 if (gcse_file
!= NULL
)
4511 fprintf (gcse_file
, "\n");
4516 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
4518 /* Reset tables used to keep track of what's still valid [since the
4519 start of the block]. */
4520 reset_opr_set_tables ();
4522 for (insn
= bb
->head
;
4523 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
4524 insn
= NEXT_INSN (insn
))
4527 changed
|= cprop_insn (insn
, alter_jumps
);
4529 /* Keep track of everything modified by this insn. */
4530 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
4531 call mark_oprs_set if we turned the insn into a NOTE. */
4532 if (GET_CODE (insn
) != NOTE
)
4533 mark_oprs_set (insn
);
4537 if (gcse_file
!= NULL
)
4538 fprintf (gcse_file
, "\n");
4543 /* Similar to get_condition, only the resulting condition must be
4544 valid at JUMP, instead of at EARLIEST.
4546 This differs from noce_get_condition in ifcvt.c in that we prefer not to
4547 settle for the condition variable in the jump instruction being integral.
4548 We prefer to be able to record the value of a user variable, rather than
4549 the value of a temporary used in a condition. This could be solved by
4550 recording the value of *every* register scaned by canonicalize_condition,
4551 but this would require some code reorganization. */
4554 fis_get_condition (jump
)
4557 rtx cond
, set
, tmp
, insn
, earliest
;
4560 if (! any_condjump_p (jump
))
4563 set
= pc_set (jump
);
4564 cond
= XEXP (SET_SRC (set
), 0);
4566 /* If this branches to JUMP_LABEL when the condition is false,
4567 reverse the condition. */
4568 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
4569 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
4571 /* Use canonicalize_condition to do the dirty work of manipulating
4572 MODE_CC values and COMPARE rtx codes. */
4573 tmp
= canonicalize_condition (jump
, cond
, reverse
, &earliest
, NULL_RTX
);
4577 /* Verify that the given condition is valid at JUMP by virtue of not
4578 having been modified since EARLIEST. */
4579 for (insn
= earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
4580 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
4585 /* The condition was modified. See if we can get a partial result
4586 that doesn't follow all the reversals. Perhaps combine can fold
4587 them together later. */
4588 tmp
= XEXP (tmp
, 0);
4589 if (!REG_P (tmp
) || GET_MODE_CLASS (GET_MODE (tmp
)) != MODE_INT
)
4591 tmp
= canonicalize_condition (jump
, cond
, reverse
, &earliest
, tmp
);
4595 /* For sanity's sake, re-validate the new result. */
4596 for (insn
= earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
4597 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
4603 /* Find the implicit sets of a function. An "implicit set" is a constraint
4604 on the value of a variable, implied by a conditional jump. For example,
4605 following "if (x == 2)", the then branch may be optimized as though the
4606 conditional performed an "explicit set", in this example, "x = 2". This
4607 function records the set patterns that are implicit at the start of each
4611 find_implicit_sets ()
4613 basic_block bb
, dest
;
4619 /* Check for more than one sucessor. */
4620 if (bb
->succ
&& bb
->succ
->succ_next
)
4622 cond
= fis_get_condition (bb
->end
);
4625 && (GET_CODE (cond
) == EQ
|| GET_CODE (cond
) == NE
)
4626 && GET_CODE (XEXP (cond
, 0)) == REG
4627 && REGNO (XEXP (cond
, 0)) >= FIRST_PSEUDO_REGISTER
4628 && CONSTANT_P (XEXP (cond
, 1)))
4630 dest
= GET_CODE (cond
) == EQ
? BRANCH_EDGE (bb
)->dest
4631 : FALLTHRU_EDGE (bb
)->dest
;
4633 if (dest
&& ! dest
->pred
->pred_next
4634 && dest
!= EXIT_BLOCK_PTR
)
4636 new = gen_rtx_SET (VOIDmode
, XEXP (cond
, 0),
4638 implicit_sets
[dest
->index
] = new;
4641 fprintf(gcse_file
, "Implicit set of reg %d in ",
4642 REGNO (XEXP (cond
, 0)));
4643 fprintf(gcse_file
, "basic block %d\n", dest
->index
);
4651 fprintf (gcse_file
, "Found %d implicit sets\n", count
);
4654 /* Perform one copy/constant propagation pass.
4655 PASS is the pass count. If CPROP_JUMPS is true, perform constant
4656 propagation into conditional jumps. If BYPASS_JUMPS is true,
4657 perform conditional jump bypassing optimizations. */
4660 one_cprop_pass (pass
, cprop_jumps
, bypass_jumps
)
4667 const_prop_count
= 0;
4668 copy_prop_count
= 0;
4670 local_cprop_pass (cprop_jumps
);
4672 /* Determine implicit sets. */
4673 implicit_sets
= (rtx
*) xcalloc (last_basic_block
, sizeof (rtx
));
4674 find_implicit_sets ();
4676 alloc_hash_table (max_cuid
, &set_hash_table
, 1);
4677 compute_hash_table (&set_hash_table
);
4679 /* Free implicit_sets before peak usage. */
4680 free (implicit_sets
);
4681 implicit_sets
= NULL
;
4684 dump_hash_table (gcse_file
, "SET", &set_hash_table
);
4685 if (set_hash_table
.n_elems
> 0)
4687 alloc_cprop_mem (last_basic_block
, set_hash_table
.n_elems
);
4688 compute_cprop_data ();
4689 changed
= cprop (cprop_jumps
);
4691 changed
|= bypass_conditional_jumps ();
4695 free_hash_table (&set_hash_table
);
4699 fprintf (gcse_file
, "CPROP of %s, pass %d: %d bytes needed, ",
4700 current_function_name
, pass
, bytes_used
);
4701 fprintf (gcse_file
, "%d const props, %d copy props\n\n",
4702 const_prop_count
, copy_prop_count
);
4704 /* Global analysis may get into infinite loops for unreachable blocks. */
4705 if (changed
&& cprop_jumps
)
4706 delete_unreachable_blocks ();
4711 /* Bypass conditional jumps. */
4713 /* The value of last_basic_block at the beginning of the jump_bypass
4714 pass. The use of redirect_edge_and_branch_force may introduce new
4715 basic blocks, but the data flow analysis is only valid for basic
4716 block indices less than bypass_last_basic_block. */
4718 static int bypass_last_basic_block
;
4720 /* Find a set of REGNO to a constant that is available at the end of basic
4721 block BB. Returns NULL if no such set is found. Based heavily upon
4724 static struct expr
*
4725 find_bypass_set (regno
, bb
)
4729 struct expr
*result
= 0;
4734 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
4738 if (TEST_BIT (cprop_avout
[bb
], set
->bitmap_index
))
4740 set
= next_set (regno
, set
);
4746 if (GET_CODE (set
->expr
) != SET
)
4749 src
= SET_SRC (set
->expr
);
4750 if (CONSTANT_P (src
))
4753 if (GET_CODE (src
) != REG
)
4756 regno
= REGNO (src
);
4762 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
4763 basic block BB which has more than one predecessor. If not NULL, SETCC
4764 is the first instruction of BB, which is immediately followed by JUMP_INSN
4765 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
4766 Returns nonzero if a change was made. */
4769 bypass_block (bb
, setcc
, jump
)
4777 insn
= (setcc
!= NULL
) ? setcc
: jump
;
4779 /* Determine set of register uses in INSN. */
4781 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4782 note
= find_reg_equal_equiv_note (insn
);
4784 find_used_regs (&XEXP (note
, 0), NULL
);
4787 for (e
= bb
->pred
; e
; e
= enext
)
4789 enext
= e
->pred_next
;
4790 if (e
->flags
& EDGE_COMPLEX
)
4793 /* We can't redirect edges from new basic blocks. */
4794 if (e
->src
->index
>= bypass_last_basic_block
)
4797 for (i
= 0; i
< reg_use_count
; i
++)
4799 struct reg_use
*reg_used
= ®_use_table
[i
];
4800 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
4801 basic_block dest
, old_dest
;
4805 if (regno
>= max_gcse_regno
)
4808 set
= find_bypass_set (regno
, e
->src
->index
);
4813 src
= SET_SRC (pc_set (jump
));
4816 src
= simplify_replace_rtx (src
,
4817 SET_DEST (PATTERN (setcc
)),
4818 SET_SRC (PATTERN (setcc
)));
4820 new = simplify_replace_rtx (src
, reg_used
->reg_rtx
,
4821 SET_SRC (set
->expr
));
4824 dest
= FALLTHRU_EDGE (bb
)->dest
;
4825 else if (GET_CODE (new) == LABEL_REF
)
4826 dest
= BLOCK_FOR_INSN (XEXP (new, 0));
4833 && dest
!= EXIT_BLOCK_PTR
)
4835 redirect_edge_and_branch_force (e
, dest
);
4837 /* Copy the register setter to the redirected edge.
4838 Don't copy CC0 setters, as CC0 is dead after jump. */
4841 rtx pat
= PATTERN (setcc
);
4842 if (!CC0_P (SET_DEST (pat
)))
4843 insert_insn_on_edge (copy_insn (pat
), e
);
4846 if (gcse_file
!= NULL
)
4848 fprintf (gcse_file
, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
4849 regno
, INSN_UID (jump
));
4850 print_rtl (gcse_file
, SET_SRC (set
->expr
));
4851 fprintf (gcse_file
, "\nBypass edge from %d->%d to %d\n",
4852 e
->src
->index
, old_dest
->index
, dest
->index
);
4862 /* Find basic blocks with more than one predecessor that only contain a
4863 single conditional jump. If the result of the comparison is known at
4864 compile-time from any incoming edge, redirect that edge to the
4865 appropriate target. Returns nonzero if a change was made.
4867 This function is now mis-named, because we also handle indirect jumps. */
4870 bypass_conditional_jumps ()
4878 /* Note we start at block 1. */
4879 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
4882 bypass_last_basic_block
= last_basic_block
;
4885 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
,
4886 EXIT_BLOCK_PTR
, next_bb
)
4888 /* Check for more than one predecessor. */
4889 if (bb
->pred
&& bb
->pred
->pred_next
)
4892 for (insn
= bb
->head
;
4893 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
4894 insn
= NEXT_INSN (insn
))
4895 if (GET_CODE (insn
) == INSN
)
4899 if (GET_CODE (PATTERN (insn
)) != SET
)
4902 dest
= SET_DEST (PATTERN (insn
));
4903 if (REG_P (dest
) || CC0_P (dest
))
4908 else if (GET_CODE (insn
) == JUMP_INSN
)
4910 if ((any_condjump_p (insn
) || computed_jump_p (insn
))
4911 && onlyjump_p (insn
))
4912 changed
|= bypass_block (bb
, setcc
, insn
);
4915 else if (INSN_P (insn
))
4920 /* If we bypassed any register setting insns, we inserted a
4921 copy on the redirected edge. These need to be committed. */
4923 commit_edge_insertions();
4928 /* Compute PRE+LCM working variables. */
4930 /* Local properties of expressions. */
4931 /* Nonzero for expressions that are transparent in the block. */
4932 static sbitmap
*transp
;
4934 /* Nonzero for expressions that are transparent at the end of the block.
4935 This is only zero for expressions killed by abnormal critical edge
4936 created by a calls. */
4937 static sbitmap
*transpout
;
4939 /* Nonzero for expressions that are computed (available) in the block. */
4940 static sbitmap
*comp
;
4942 /* Nonzero for expressions that are locally anticipatable in the block. */
4943 static sbitmap
*antloc
;
4945 /* Nonzero for expressions where this block is an optimal computation
4947 static sbitmap
*pre_optimal
;
4949 /* Nonzero for expressions which are redundant in a particular block. */
4950 static sbitmap
*pre_redundant
;
4952 /* Nonzero for expressions which should be inserted on a specific edge. */
4953 static sbitmap
*pre_insert_map
;
4955 /* Nonzero for expressions which should be deleted in a specific block. */
4956 static sbitmap
*pre_delete_map
;
4958 /* Contains the edge_list returned by pre_edge_lcm. */
4959 static struct edge_list
*edge_list
;
4961 /* Redundant insns. */
4962 static sbitmap pre_redundant_insns
;
4964 /* Allocate vars used for PRE analysis. */
4967 alloc_pre_mem (n_blocks
, n_exprs
)
4968 int n_blocks
, n_exprs
;
4970 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4971 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4972 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4975 pre_redundant
= NULL
;
4976 pre_insert_map
= NULL
;
4977 pre_delete_map
= NULL
;
4980 ae_kill
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4982 /* pre_insert and pre_delete are allocated later. */
4985 /* Free vars used for PRE analysis. */
4990 sbitmap_vector_free (transp
);
4991 sbitmap_vector_free (comp
);
4993 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
4996 sbitmap_vector_free (pre_optimal
);
4998 sbitmap_vector_free (pre_redundant
);
5000 sbitmap_vector_free (pre_insert_map
);
5002 sbitmap_vector_free (pre_delete_map
);
5004 sbitmap_vector_free (ae_in
);
5006 sbitmap_vector_free (ae_out
);
5008 transp
= comp
= NULL
;
5009 pre_optimal
= pre_redundant
= pre_insert_map
= pre_delete_map
= NULL
;
5010 ae_in
= ae_out
= NULL
;
5013 /* Top level routine to do the dataflow analysis needed by PRE. */
5018 sbitmap trapping_expr
;
5022 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
5023 sbitmap_vector_zero (ae_kill
, last_basic_block
);
5025 /* Collect expressions which might trap. */
5026 trapping_expr
= sbitmap_alloc (expr_hash_table
.n_elems
);
5027 sbitmap_zero (trapping_expr
);
5028 for (ui
= 0; ui
< expr_hash_table
.size
; ui
++)
5031 for (e
= expr_hash_table
.table
[ui
]; e
!= NULL
; e
= e
->next_same_hash
)
5032 if (may_trap_p (e
->expr
))
5033 SET_BIT (trapping_expr
, e
->bitmap_index
);
5036 /* Compute ae_kill for each basic block using:
5040 This is significantly faster than compute_ae_kill. */
5046 /* If the current block is the destination of an abnormal edge, we
5047 kill all trapping expressions because we won't be able to properly
5048 place the instruction on the edge. So make them neither
5049 anticipatable nor transparent. This is fairly conservative. */
5050 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
5051 if (e
->flags
& EDGE_ABNORMAL
)
5053 sbitmap_difference (antloc
[bb
->index
], antloc
[bb
->index
], trapping_expr
);
5054 sbitmap_difference (transp
[bb
->index
], transp
[bb
->index
], trapping_expr
);
5058 sbitmap_a_or_b (ae_kill
[bb
->index
], transp
[bb
->index
], comp
[bb
->index
]);
5059 sbitmap_not (ae_kill
[bb
->index
], ae_kill
[bb
->index
]);
5062 edge_list
= pre_edge_lcm (gcse_file
, expr_hash_table
.n_elems
, transp
, comp
, antloc
,
5063 ae_kill
, &pre_insert_map
, &pre_delete_map
);
5064 sbitmap_vector_free (antloc
);
5066 sbitmap_vector_free (ae_kill
);
5068 sbitmap_free (trapping_expr
);
5073 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
5076 VISITED is a pointer to a working buffer for tracking which BB's have
5077 been visited. It is NULL for the top-level call.
5079 We treat reaching expressions that go through blocks containing the same
5080 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
5081 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
5082 2 as not reaching. The intent is to improve the probability of finding
5083 only one reaching expression and to reduce register lifetimes by picking
5084 the closest such expression. */
5087 pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
)
5088 basic_block occr_bb
;
5095 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
5097 basic_block pred_bb
= pred
->src
;
5099 if (pred
->src
== ENTRY_BLOCK_PTR
5100 /* Has predecessor has already been visited? */
5101 || visited
[pred_bb
->index
])
5102 ;/* Nothing to do. */
5104 /* Does this predecessor generate this expression? */
5105 else if (TEST_BIT (comp
[pred_bb
->index
], expr
->bitmap_index
))
5107 /* Is this the occurrence we're looking for?
5108 Note that there's only one generating occurrence per block
5109 so we just need to check the block number. */
5110 if (occr_bb
== pred_bb
)
5113 visited
[pred_bb
->index
] = 1;
5115 /* Ignore this predecessor if it kills the expression. */
5116 else if (! TEST_BIT (transp
[pred_bb
->index
], expr
->bitmap_index
))
5117 visited
[pred_bb
->index
] = 1;
5119 /* Neither gen nor kill. */
5122 visited
[pred_bb
->index
] = 1;
5123 if (pre_expr_reaches_here_p_work (occr_bb
, expr
, pred_bb
, visited
))
5128 /* All paths have been checked. */
5132 /* The wrapper for pre_expr_reaches_here_work that ensures that any
5133 memory allocated for that function is returned. */
5136 pre_expr_reaches_here_p (occr_bb
, expr
, bb
)
5137 basic_block occr_bb
;
5142 char *visited
= (char *) xcalloc (last_basic_block
, 1);
5144 rval
= pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
);
5151 /* Given an expr, generate RTL which we can insert at the end of a BB,
5152 or on an edge. Set the block number of any insns generated to
5156 process_insert_insn (expr
)
5159 rtx reg
= expr
->reaching_reg
;
5160 rtx exp
= copy_rtx (expr
->expr
);
5165 /* If the expression is something that's an operand, like a constant,
5166 just copy it to a register. */
5167 if (general_operand (exp
, GET_MODE (reg
)))
5168 emit_move_insn (reg
, exp
);
5170 /* Otherwise, make a new insn to compute this expression and make sure the
5171 insn will be recognized (this also adds any needed CLOBBERs). Copy the
5172 expression to make sure we don't have any sharing issues. */
5173 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode
, reg
, exp
))))
5182 /* Add EXPR to the end of basic block BB.
5184 This is used by both the PRE and code hoisting.
5186 For PRE, we want to verify that the expr is either transparent
5187 or locally anticipatable in the target block. This check makes
5188 no sense for code hoisting. */
5191 insert_insn_end_bb (expr
, bb
, pre
)
5198 rtx reg
= expr
->reaching_reg
;
5199 int regno
= REGNO (reg
);
5202 pat
= process_insert_insn (expr
);
5203 if (pat
== NULL_RTX
|| ! INSN_P (pat
))
5207 while (NEXT_INSN (pat_end
) != NULL_RTX
)
5208 pat_end
= NEXT_INSN (pat_end
);
5210 /* If the last insn is a jump, insert EXPR in front [taking care to
5211 handle cc0, etc. properly]. Similary we need to care trapping
5212 instructions in presence of non-call exceptions. */
5214 if (GET_CODE (insn
) == JUMP_INSN
5215 || (GET_CODE (insn
) == INSN
5216 && (bb
->succ
->succ_next
|| (bb
->succ
->flags
& EDGE_ABNORMAL
))))
5221 /* It should always be the case that we can put these instructions
5222 anywhere in the basic block with performing PRE optimizations.
5224 if (GET_CODE (insn
) == INSN
&& pre
5225 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
5226 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
5229 /* If this is a jump table, then we can't insert stuff here. Since
5230 we know the previous real insn must be the tablejump, we insert
5231 the new instruction just before the tablejump. */
5232 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
5233 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
5234 insn
= prev_real_insn (insn
);
5237 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
5238 if cc0 isn't set. */
5239 note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
5241 insn
= XEXP (note
, 0);
5244 rtx maybe_cc0_setter
= prev_nonnote_insn (insn
);
5245 if (maybe_cc0_setter
5246 && INSN_P (maybe_cc0_setter
)
5247 && sets_cc0_p (PATTERN (maybe_cc0_setter
)))
5248 insn
= maybe_cc0_setter
;
5251 /* FIXME: What if something in cc0/jump uses value set in new insn? */
5252 new_insn
= emit_insn_before (pat
, insn
);
5255 /* Likewise if the last insn is a call, as will happen in the presence
5256 of exception handling. */
5257 else if (GET_CODE (insn
) == CALL_INSN
5258 && (bb
->succ
->succ_next
|| (bb
->succ
->flags
& EDGE_ABNORMAL
)))
5260 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
5261 we search backward and place the instructions before the first
5262 parameter is loaded. Do this for everyone for consistency and a
5263 presumption that we'll get better code elsewhere as well.
5265 It should always be the case that we can put these instructions
5266 anywhere in the basic block with performing PRE optimizations.
5270 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
5271 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
5274 /* Since different machines initialize their parameter registers
5275 in different orders, assume nothing. Collect the set of all
5276 parameter registers. */
5277 insn
= find_first_parameter_load (insn
, bb
->head
);
5279 /* If we found all the parameter loads, then we want to insert
5280 before the first parameter load.
5282 If we did not find all the parameter loads, then we might have
5283 stopped on the head of the block, which could be a CODE_LABEL.
5284 If we inserted before the CODE_LABEL, then we would be putting
5285 the insn in the wrong basic block. In that case, put the insn
5286 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
5287 while (GET_CODE (insn
) == CODE_LABEL
5288 || NOTE_INSN_BASIC_BLOCK_P (insn
))
5289 insn
= NEXT_INSN (insn
);
5291 new_insn
= emit_insn_before (pat
, insn
);
5294 new_insn
= emit_insn_after (pat
, insn
);
5300 add_label_notes (PATTERN (pat
), new_insn
);
5301 note_stores (PATTERN (pat
), record_set_info
, pat
);
5305 pat
= NEXT_INSN (pat
);
5308 gcse_create_count
++;
5312 fprintf (gcse_file
, "PRE/HOIST: end of bb %d, insn %d, ",
5313 bb
->index
, INSN_UID (new_insn
));
5314 fprintf (gcse_file
, "copying expression %d to reg %d\n",
5315 expr
->bitmap_index
, regno
);
5319 /* Insert partially redundant expressions on edges in the CFG to make
5320 the expressions fully redundant. */
5323 pre_edge_insert (edge_list
, index_map
)
5324 struct edge_list
*edge_list
;
5325 struct expr
**index_map
;
5327 int e
, i
, j
, num_edges
, set_size
, did_insert
= 0;
5330 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
5331 if it reaches any of the deleted expressions. */
5333 set_size
= pre_insert_map
[0]->size
;
5334 num_edges
= NUM_EDGES (edge_list
);
5335 inserted
= sbitmap_vector_alloc (num_edges
, expr_hash_table
.n_elems
);
5336 sbitmap_vector_zero (inserted
, num_edges
);
5338 for (e
= 0; e
< num_edges
; e
++)
5341 basic_block bb
= INDEX_EDGE_PRED_BB (edge_list
, e
);
5343 for (i
= indx
= 0; i
< set_size
; i
++, indx
+= SBITMAP_ELT_BITS
)
5345 SBITMAP_ELT_TYPE insert
= pre_insert_map
[e
]->elms
[i
];
5347 for (j
= indx
; insert
&& j
< (int) expr_hash_table
.n_elems
; j
++, insert
>>= 1)
5348 if ((insert
& 1) != 0 && index_map
[j
]->reaching_reg
!= NULL_RTX
)
5350 struct expr
*expr
= index_map
[j
];
5353 /* Now look at each deleted occurrence of this expression. */
5354 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5356 if (! occr
->deleted_p
)
5359 /* Insert this expression on this edge if if it would
5360 reach the deleted occurrence in BB. */
5361 if (!TEST_BIT (inserted
[e
], j
))
5364 edge eg
= INDEX_EDGE (edge_list
, e
);
5366 /* We can't insert anything on an abnormal and
5367 critical edge, so we insert the insn at the end of
5368 the previous block. There are several alternatives
5369 detailed in Morgans book P277 (sec 10.5) for
5370 handling this situation. This one is easiest for
5373 if ((eg
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
5374 insert_insn_end_bb (index_map
[j
], bb
, 0);
5377 insn
= process_insert_insn (index_map
[j
]);
5378 insert_insn_on_edge (insn
, eg
);
5383 fprintf (gcse_file
, "PRE/HOIST: edge (%d,%d), ",
5385 INDEX_EDGE_SUCC_BB (edge_list
, e
)->index
);
5386 fprintf (gcse_file
, "copy expression %d\n",
5387 expr
->bitmap_index
);
5390 update_ld_motion_stores (expr
);
5391 SET_BIT (inserted
[e
], j
);
5393 gcse_create_count
++;
5400 sbitmap_vector_free (inserted
);
5404 /* Copy the result of INSN to REG. INDX is the expression number. */
5407 pre_insert_copy_insn (expr
, insn
)
5411 rtx reg
= expr
->reaching_reg
;
5412 int regno
= REGNO (reg
);
5413 int indx
= expr
->bitmap_index
;
5414 rtx set
= single_set (insn
);
5420 new_insn
= emit_insn_after (gen_move_insn (reg
, SET_DEST (set
)), insn
);
5422 /* Keep register set table up to date. */
5423 record_one_set (regno
, new_insn
);
5425 gcse_create_count
++;
5429 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
5430 BLOCK_NUM (insn
), INSN_UID (new_insn
), indx
,
5431 INSN_UID (insn
), regno
);
5432 update_ld_motion_stores (expr
);
5435 /* Copy available expressions that reach the redundant expression
5436 to `reaching_reg'. */
5439 pre_insert_copies ()
5446 /* For each available expression in the table, copy the result to
5447 `reaching_reg' if the expression reaches a deleted one.
5449 ??? The current algorithm is rather brute force.
5450 Need to do some profiling. */
5452 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5453 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5455 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
5456 we don't want to insert a copy here because the expression may not
5457 really be redundant. So only insert an insn if the expression was
5458 deleted. This test also avoids further processing if the
5459 expression wasn't deleted anywhere. */
5460 if (expr
->reaching_reg
== NULL
)
5463 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5465 if (! occr
->deleted_p
)
5468 for (avail
= expr
->avail_occr
; avail
!= NULL
; avail
= avail
->next
)
5470 rtx insn
= avail
->insn
;
5472 /* No need to handle this one if handled already. */
5473 if (avail
->copied_p
)
5476 /* Don't handle this one if it's a redundant one. */
5477 if (TEST_BIT (pre_redundant_insns
, INSN_CUID (insn
)))
5480 /* Or if the expression doesn't reach the deleted one. */
5481 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail
->insn
),
5483 BLOCK_FOR_INSN (occr
->insn
)))
5486 /* Copy the result of avail to reaching_reg. */
5487 pre_insert_copy_insn (expr
, insn
);
5488 avail
->copied_p
= 1;
5494 /* Emit move from SRC to DEST noting the equivalence with expression computed
5497 gcse_emit_move_after (src
, dest
, insn
)
5498 rtx src
, dest
, insn
;
5501 rtx set
= single_set (insn
), set2
;
5505 /* This should never fail since we're creating a reg->reg copy
5506 we've verified to be valid. */
5508 new = emit_insn_after (gen_move_insn (dest
, src
), insn
);
5510 /* Note the equivalence for local CSE pass. */
5511 set2
= single_set (new);
5512 if (!set2
|| !rtx_equal_p (SET_DEST (set2
), dest
))
5514 if ((note
= find_reg_equal_equiv_note (insn
)))
5515 eqv
= XEXP (note
, 0);
5517 eqv
= SET_SRC (set
);
5519 set_unique_reg_note (new, REG_EQUAL
, copy_insn_1 (eqv
));
5524 /* Delete redundant computations.
5525 Deletion is done by changing the insn to copy the `reaching_reg' of
5526 the expression into the result of the SET. It is left to later passes
5527 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
5529 Returns nonzero if a change is made. */
5540 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5541 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5543 int indx
= expr
->bitmap_index
;
5545 /* We only need to search antic_occr since we require
5548 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5550 rtx insn
= occr
->insn
;
5552 basic_block bb
= BLOCK_FOR_INSN (insn
);
5554 if (TEST_BIT (pre_delete_map
[bb
->index
], indx
))
5556 set
= single_set (insn
);
5560 /* Create a pseudo-reg to store the result of reaching
5561 expressions into. Get the mode for the new pseudo from
5562 the mode of the original destination pseudo. */
5563 if (expr
->reaching_reg
== NULL
)
5565 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
5567 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
5569 occr
->deleted_p
= 1;
5570 SET_BIT (pre_redundant_insns
, INSN_CUID (insn
));
5577 "PRE: redundant insn %d (expression %d) in ",
5578 INSN_UID (insn
), indx
);
5579 fprintf (gcse_file
, "bb %d, reaching reg is %d\n",
5580 bb
->index
, REGNO (expr
->reaching_reg
));
5589 /* Perform GCSE optimizations using PRE.
5590 This is called by one_pre_gcse_pass after all the dataflow analysis
5593 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
5594 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
5595 Compiler Design and Implementation.
5597 ??? A new pseudo reg is created to hold the reaching expression. The nice
5598 thing about the classical approach is that it would try to use an existing
5599 reg. If the register can't be adequately optimized [i.e. we introduce
5600 reload problems], one could add a pass here to propagate the new register
5603 ??? We don't handle single sets in PARALLELs because we're [currently] not
5604 able to copy the rest of the parallel when we insert copies to create full
5605 redundancies from partial redundancies. However, there's no reason why we
5606 can't handle PARALLELs in the cases where there are no partial
5613 int did_insert
, changed
;
5614 struct expr
**index_map
;
5617 /* Compute a mapping from expression number (`bitmap_index') to
5618 hash table entry. */
5620 index_map
= (struct expr
**) xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
5621 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5622 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5623 index_map
[expr
->bitmap_index
] = expr
;
5625 /* Reset bitmap used to track which insns are redundant. */
5626 pre_redundant_insns
= sbitmap_alloc (max_cuid
);
5627 sbitmap_zero (pre_redundant_insns
);
5629 /* Delete the redundant insns first so that
5630 - we know what register to use for the new insns and for the other
5631 ones with reaching expressions
5632 - we know which insns are redundant when we go to create copies */
5634 changed
= pre_delete ();
5636 did_insert
= pre_edge_insert (edge_list
, index_map
);
5638 /* In other places with reaching expressions, copy the expression to the
5639 specially allocated pseudo-reg that reaches the redundant expr. */
5640 pre_insert_copies ();
5643 commit_edge_insertions ();
5648 sbitmap_free (pre_redundant_insns
);
5652 /* Top level routine to perform one PRE GCSE pass.
5654 Return nonzero if a change was made. */
5657 one_pre_gcse_pass (pass
)
5662 gcse_subst_count
= 0;
5663 gcse_create_count
= 0;
5665 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
5666 add_noreturn_fake_exit_edges ();
5668 compute_ld_motion_mems ();
5670 compute_hash_table (&expr_hash_table
);
5671 trim_ld_motion_mems ();
5673 dump_hash_table (gcse_file
, "Expression", &expr_hash_table
);
5675 if (expr_hash_table
.n_elems
> 0)
5677 alloc_pre_mem (last_basic_block
, expr_hash_table
.n_elems
);
5678 compute_pre_data ();
5679 changed
|= pre_gcse ();
5680 free_edge_list (edge_list
);
5685 remove_fake_edges ();
5686 free_hash_table (&expr_hash_table
);
5690 fprintf (gcse_file
, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
5691 current_function_name
, pass
, bytes_used
);
5692 fprintf (gcse_file
, "%d substs, %d insns created\n",
5693 gcse_subst_count
, gcse_create_count
);
5699 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
5700 If notes are added to an insn which references a CODE_LABEL, the
5701 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
5702 because the following loop optimization pass requires them. */
5704 /* ??? This is very similar to the loop.c add_label_notes function. We
5705 could probably share code here. */
5707 /* ??? If there was a jump optimization pass after gcse and before loop,
5708 then we would not need to do this here, because jump would add the
5709 necessary REG_LABEL notes. */
5712 add_label_notes (x
, insn
)
5716 enum rtx_code code
= GET_CODE (x
);
5720 if (code
== LABEL_REF
&& !LABEL_REF_NONLOCAL_P (x
))
5722 /* This code used to ignore labels that referred to dispatch tables to
5723 avoid flow generating (slighly) worse code.
5725 We no longer ignore such label references (see LABEL_REF handling in
5726 mark_jump_label for additional information). */
5728 REG_NOTES (insn
) = gen_rtx_INSN_LIST (REG_LABEL
, XEXP (x
, 0),
5730 if (LABEL_P (XEXP (x
, 0)))
5731 LABEL_NUSES (XEXP (x
, 0))++;
5735 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
5738 add_label_notes (XEXP (x
, i
), insn
);
5739 else if (fmt
[i
] == 'E')
5740 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5741 add_label_notes (XVECEXP (x
, i
, j
), insn
);
5745 /* Compute transparent outgoing information for each block.
5747 An expression is transparent to an edge unless it is killed by
5748 the edge itself. This can only happen with abnormal control flow,
5749 when the edge is traversed through a call. This happens with
5750 non-local labels and exceptions.
5752 This would not be necessary if we split the edge. While this is
5753 normally impossible for abnormal critical edges, with some effort
5754 it should be possible with exception handling, since we still have
5755 control over which handler should be invoked. But due to increased
5756 EH table sizes, this may not be worthwhile. */
5759 compute_transpout ()
5765 sbitmap_vector_ones (transpout
, last_basic_block
);
5769 /* Note that flow inserted a nop a the end of basic blocks that
5770 end in call instructions for reasons other than abnormal
5772 if (GET_CODE (bb
->end
) != CALL_INSN
)
5775 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5776 for (expr
= expr_hash_table
.table
[i
]; expr
; expr
= expr
->next_same_hash
)
5777 if (GET_CODE (expr
->expr
) == MEM
)
5779 if (GET_CODE (XEXP (expr
->expr
, 0)) == SYMBOL_REF
5780 && CONSTANT_POOL_ADDRESS_P (XEXP (expr
->expr
, 0)))
5783 /* ??? Optimally, we would use interprocedural alias
5784 analysis to determine if this mem is actually killed
5786 RESET_BIT (transpout
[bb
->index
], expr
->bitmap_index
);
5791 /* Removal of useless null pointer checks */
5793 /* Called via note_stores. X is set by SETTER. If X is a register we must
5794 invalidate nonnull_local and set nonnull_killed. DATA is really a
5795 `null_pointer_info *'.
5797 We ignore hard registers. */
5800 invalidate_nonnull_info (x
, setter
, data
)
5802 rtx setter ATTRIBUTE_UNUSED
;
5806 struct null_pointer_info
*npi
= (struct null_pointer_info
*) data
;
5808 while (GET_CODE (x
) == SUBREG
)
5811 /* Ignore anything that is not a register or is a hard register. */
5812 if (GET_CODE (x
) != REG
5813 || REGNO (x
) < npi
->min_reg
5814 || REGNO (x
) >= npi
->max_reg
)
5817 regno
= REGNO (x
) - npi
->min_reg
;
5819 RESET_BIT (npi
->nonnull_local
[npi
->current_block
->index
], regno
);
5820 SET_BIT (npi
->nonnull_killed
[npi
->current_block
->index
], regno
);
5823 /* Do null-pointer check elimination for the registers indicated in
5824 NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
5825 they are not our responsibility to free. */
5828 delete_null_pointer_checks_1 (block_reg
, nonnull_avin
,
5830 unsigned int *block_reg
;
5831 sbitmap
*nonnull_avin
;
5832 sbitmap
*nonnull_avout
;
5833 struct null_pointer_info
*npi
;
5835 basic_block bb
, current_block
;
5836 sbitmap
*nonnull_local
= npi
->nonnull_local
;
5837 sbitmap
*nonnull_killed
= npi
->nonnull_killed
;
5838 int something_changed
= 0;
5840 /* Compute local properties, nonnull and killed. A register will have
5841 the nonnull property if at the end of the current block its value is
5842 known to be nonnull. The killed property indicates that somewhere in
5843 the block any information we had about the register is killed.
5845 Note that a register can have both properties in a single block. That
5846 indicates that it's killed, then later in the block a new value is
5848 sbitmap_vector_zero (nonnull_local
, last_basic_block
);
5849 sbitmap_vector_zero (nonnull_killed
, last_basic_block
);
5851 FOR_EACH_BB (current_block
)
5853 rtx insn
, stop_insn
;
5855 /* Set the current block for invalidate_nonnull_info. */
5856 npi
->current_block
= current_block
;
5858 /* Scan each insn in the basic block looking for memory references and
5860 stop_insn
= NEXT_INSN (current_block
->end
);
5861 for (insn
= current_block
->head
;
5863 insn
= NEXT_INSN (insn
))
5868 /* Ignore anything that is not a normal insn. */
5869 if (! INSN_P (insn
))
5872 /* Basically ignore anything that is not a simple SET. We do have
5873 to make sure to invalidate nonnull_local and set nonnull_killed
5874 for such insns though. */
5875 set
= single_set (insn
);
5878 note_stores (PATTERN (insn
), invalidate_nonnull_info
, npi
);
5882 /* See if we've got a usable memory load. We handle it first
5883 in case it uses its address register as a dest (which kills
5884 the nonnull property). */
5885 if (GET_CODE (SET_SRC (set
)) == MEM
5886 && GET_CODE ((reg
= XEXP (SET_SRC (set
), 0))) == REG
5887 && REGNO (reg
) >= npi
->min_reg
5888 && REGNO (reg
) < npi
->max_reg
)
5889 SET_BIT (nonnull_local
[current_block
->index
],
5890 REGNO (reg
) - npi
->min_reg
);
5892 /* Now invalidate stuff clobbered by this insn. */
5893 note_stores (PATTERN (insn
), invalidate_nonnull_info
, npi
);
5895 /* And handle stores, we do these last since any sets in INSN can
5896 not kill the nonnull property if it is derived from a MEM
5897 appearing in a SET_DEST. */
5898 if (GET_CODE (SET_DEST (set
)) == MEM
5899 && GET_CODE ((reg
= XEXP (SET_DEST (set
), 0))) == REG
5900 && REGNO (reg
) >= npi
->min_reg
5901 && REGNO (reg
) < npi
->max_reg
)
5902 SET_BIT (nonnull_local
[current_block
->index
],
5903 REGNO (reg
) - npi
->min_reg
);
5907 /* Now compute global properties based on the local properties. This
5908 is a classic global availability algorithm. */
5909 compute_available (nonnull_local
, nonnull_killed
,
5910 nonnull_avout
, nonnull_avin
);
5912 /* Now look at each bb and see if it ends with a compare of a value
5916 rtx last_insn
= bb
->end
;
5917 rtx condition
, earliest
;
5918 int compare_and_branch
;
5920 /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
5921 since BLOCK_REG[BB] is zero if this block did not end with a
5922 comparison against zero, this condition works. */
5923 if (block_reg
[bb
->index
] < npi
->min_reg
5924 || block_reg
[bb
->index
] >= npi
->max_reg
)
5927 /* LAST_INSN is a conditional jump. Get its condition. */
5928 condition
= get_condition (last_insn
, &earliest
);
5930 /* If we can't determine the condition then skip. */
5934 /* Is the register known to have a nonzero value? */
5935 if (!TEST_BIT (nonnull_avout
[bb
->index
], block_reg
[bb
->index
] - npi
->min_reg
))
5938 /* Try to compute whether the compare/branch at the loop end is one or
5939 two instructions. */
5940 if (earliest
== last_insn
)
5941 compare_and_branch
= 1;
5942 else if (earliest
== prev_nonnote_insn (last_insn
))
5943 compare_and_branch
= 2;
5947 /* We know the register in this comparison is nonnull at exit from
5948 this block. We can optimize this comparison. */
5949 if (GET_CODE (condition
) == NE
)
5953 new_jump
= emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn
)),
5955 JUMP_LABEL (new_jump
) = JUMP_LABEL (last_insn
);
5956 LABEL_NUSES (JUMP_LABEL (new_jump
))++;
5957 emit_barrier_after (new_jump
);
5960 something_changed
= 1;
5961 delete_insn (last_insn
);
5962 if (compare_and_branch
== 2)
5963 delete_insn (earliest
);
5964 purge_dead_edges (bb
);
5966 /* Don't check this block again. (Note that BLOCK_END is
5967 invalid here; we deleted the last instruction in the
5969 block_reg
[bb
->index
] = 0;
5972 return something_changed
;
5975 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
5978 This is conceptually similar to global constant/copy propagation and
5979 classic global CSE (it even uses the same dataflow equations as cprop).
5981 If a register is used as memory address with the form (mem (reg)), then we
5982 know that REG can not be zero at that point in the program. Any instruction
5983 which sets REG "kills" this property.
5985 So, if every path leading to a conditional branch has an available memory
5986 reference of that form, then we know the register can not have the value
5987 zero at the conditional branch.
5989 So we merely need to compute the local properties and propagate that data
5990 around the cfg, then optimize where possible.
5992 We run this pass two times. Once before CSE, then again after CSE. This
5993 has proven to be the most profitable approach. It is rare for new
5994 optimization opportunities of this nature to appear after the first CSE
5997 This could probably be integrated with global cprop with a little work. */
6000 delete_null_pointer_checks (f
)
6001 rtx f ATTRIBUTE_UNUSED
;
6003 sbitmap
*nonnull_avin
, *nonnull_avout
;
6004 unsigned int *block_reg
;
6009 struct null_pointer_info npi
;
6010 int something_changed
= 0;
6012 /* If we have only a single block, then there's nothing to do. */
6013 if (n_basic_blocks
<= 1)
6016 /* Trying to perform global optimizations on flow graphs which have
6017 a high connectivity will take a long time and is unlikely to be
6018 particularly useful.
6020 In normal circumstances a cfg should have about twice as many edges
6021 as blocks. But we do not want to punish small functions which have
6022 a couple switch statements. So we require a relatively large number
6023 of basic blocks and the ratio of edges to blocks to be high. */
6024 if (n_basic_blocks
> 1000 && n_edges
/ n_basic_blocks
>= 20)
6027 /* We need four bitmaps, each with a bit for each register in each
6029 max_reg
= max_reg_num ();
6030 regs_per_pass
= get_bitmap_width (4, last_basic_block
, max_reg
);
6032 /* Allocate bitmaps to hold local and global properties. */
6033 npi
.nonnull_local
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6034 npi
.nonnull_killed
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6035 nonnull_avin
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6036 nonnull_avout
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6038 /* Go through the basic blocks, seeing whether or not each block
6039 ends with a conditional branch whose condition is a comparison
6040 against zero. Record the register compared in BLOCK_REG. */
6041 block_reg
= (unsigned int *) xcalloc (last_basic_block
, sizeof (int));
6044 rtx last_insn
= bb
->end
;
6045 rtx condition
, earliest
, reg
;
6047 /* We only want conditional branches. */
6048 if (GET_CODE (last_insn
) != JUMP_INSN
6049 || !any_condjump_p (last_insn
)
6050 || !onlyjump_p (last_insn
))
6053 /* LAST_INSN is a conditional jump. Get its condition. */
6054 condition
= get_condition (last_insn
, &earliest
);
6056 /* If we were unable to get the condition, or it is not an equality
6057 comparison against zero then there's nothing we can do. */
6059 || (GET_CODE (condition
) != NE
&& GET_CODE (condition
) != EQ
)
6060 || GET_CODE (XEXP (condition
, 1)) != CONST_INT
6061 || (XEXP (condition
, 1)
6062 != CONST0_RTX (GET_MODE (XEXP (condition
, 0)))))
6065 /* We must be checking a register against zero. */
6066 reg
= XEXP (condition
, 0);
6067 if (GET_CODE (reg
) != REG
)
6070 block_reg
[bb
->index
] = REGNO (reg
);
6073 /* Go through the algorithm for each block of registers. */
6074 for (reg
= FIRST_PSEUDO_REGISTER
; reg
< max_reg
; reg
+= regs_per_pass
)
6077 npi
.max_reg
= MIN (reg
+ regs_per_pass
, max_reg
);
6078 something_changed
|= delete_null_pointer_checks_1 (block_reg
,
6084 /* Free the table of registers compared at the end of every block. */
6088 sbitmap_vector_free (npi
.nonnull_local
);
6089 sbitmap_vector_free (npi
.nonnull_killed
);
6090 sbitmap_vector_free (nonnull_avin
);
6091 sbitmap_vector_free (nonnull_avout
);
6093 return something_changed
;
6096 /* Code Hoisting variables and subroutines. */
6098 /* Very busy expressions. */
6099 static sbitmap
*hoist_vbein
;
6100 static sbitmap
*hoist_vbeout
;
6102 /* Hoistable expressions. */
6103 static sbitmap
*hoist_exprs
;
6105 /* Dominator bitmaps. */
6106 dominance_info dominators
;
6108 /* ??? We could compute post dominators and run this algorithm in
6109 reverse to perform tail merging, doing so would probably be
6110 more effective than the tail merging code in jump.c.
6112 It's unclear if tail merging could be run in parallel with
6113 code hoisting. It would be nice. */
6115 /* Allocate vars used for code hoisting analysis. */
6118 alloc_code_hoist_mem (n_blocks
, n_exprs
)
6119 int n_blocks
, n_exprs
;
6121 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6122 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6123 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6125 hoist_vbein
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6126 hoist_vbeout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6127 hoist_exprs
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6128 transpout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6131 /* Free vars used for code hoisting analysis. */
6134 free_code_hoist_mem ()
6136 sbitmap_vector_free (antloc
);
6137 sbitmap_vector_free (transp
);
6138 sbitmap_vector_free (comp
);
6140 sbitmap_vector_free (hoist_vbein
);
6141 sbitmap_vector_free (hoist_vbeout
);
6142 sbitmap_vector_free (hoist_exprs
);
6143 sbitmap_vector_free (transpout
);
6145 free_dominance_info (dominators
);
6148 /* Compute the very busy expressions at entry/exit from each block.
6150 An expression is very busy if all paths from a given point
6151 compute the expression. */
6154 compute_code_hoist_vbeinout ()
6156 int changed
, passes
;
6159 sbitmap_vector_zero (hoist_vbeout
, last_basic_block
);
6160 sbitmap_vector_zero (hoist_vbein
, last_basic_block
);
6169 /* We scan the blocks in the reverse order to speed up
6171 FOR_EACH_BB_REVERSE (bb
)
6173 changed
|= sbitmap_a_or_b_and_c_cg (hoist_vbein
[bb
->index
], antloc
[bb
->index
],
6174 hoist_vbeout
[bb
->index
], transp
[bb
->index
]);
6175 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
6176 sbitmap_intersection_of_succs (hoist_vbeout
[bb
->index
], hoist_vbein
, bb
->index
);
6183 fprintf (gcse_file
, "hoisting vbeinout computation: %d passes\n", passes
);
6186 /* Top level routine to do the dataflow analysis needed by code hoisting. */
6189 compute_code_hoist_data ()
6191 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
6192 compute_transpout ();
6193 compute_code_hoist_vbeinout ();
6194 dominators
= calculate_dominance_info (CDI_DOMINATORS
);
6196 fprintf (gcse_file
, "\n");
6199 /* Determine if the expression identified by EXPR_INDEX would
6200 reach BB unimpared if it was placed at the end of EXPR_BB.
6202 It's unclear exactly what Muchnick meant by "unimpared". It seems
6203 to me that the expression must either be computed or transparent in
6204 *every* block in the path(s) from EXPR_BB to BB. Any other definition
6205 would allow the expression to be hoisted out of loops, even if
6206 the expression wasn't a loop invariant.
6208 Contrast this to reachability for PRE where an expression is
6209 considered reachable if *any* path reaches instead of *all*
6213 hoist_expr_reaches_here_p (expr_bb
, expr_index
, bb
, visited
)
6214 basic_block expr_bb
;
6220 int visited_allocated_locally
= 0;
6223 if (visited
== NULL
)
6225 visited_allocated_locally
= 1;
6226 visited
= xcalloc (last_basic_block
, 1);
6229 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
6231 basic_block pred_bb
= pred
->src
;
6233 if (pred
->src
== ENTRY_BLOCK_PTR
)
6235 else if (pred_bb
== expr_bb
)
6237 else if (visited
[pred_bb
->index
])
6240 /* Does this predecessor generate this expression? */
6241 else if (TEST_BIT (comp
[pred_bb
->index
], expr_index
))
6243 else if (! TEST_BIT (transp
[pred_bb
->index
], expr_index
))
6249 visited
[pred_bb
->index
] = 1;
6250 if (! hoist_expr_reaches_here_p (expr_bb
, expr_index
,
6255 if (visited_allocated_locally
)
6258 return (pred
== NULL
);
6261 /* Actually perform code hoisting. */
6266 basic_block bb
, dominated
;
6268 unsigned int domby_len
;
6270 struct expr
**index_map
;
6273 sbitmap_vector_zero (hoist_exprs
, last_basic_block
);
6275 /* Compute a mapping from expression number (`bitmap_index') to
6276 hash table entry. */
6278 index_map
= (struct expr
**) xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
6279 for (i
= 0; i
< expr_hash_table
.size
; i
++)
6280 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
6281 index_map
[expr
->bitmap_index
] = expr
;
6283 /* Walk over each basic block looking for potentially hoistable
6284 expressions, nothing gets hoisted from the entry block. */
6288 int insn_inserted_p
;
6290 domby_len
= get_dominated_by (dominators
, bb
, &domby
);
6291 /* Examine each expression that is very busy at the exit of this
6292 block. These are the potentially hoistable expressions. */
6293 for (i
= 0; i
< hoist_vbeout
[bb
->index
]->n_bits
; i
++)
6297 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
)
6298 && TEST_BIT (transpout
[bb
->index
], i
))
6300 /* We've found a potentially hoistable expression, now
6301 we look at every block BB dominates to see if it
6302 computes the expression. */
6303 for (j
= 0; j
< domby_len
; j
++)
6305 dominated
= domby
[j
];
6306 /* Ignore self dominance. */
6307 if (bb
== dominated
)
6309 /* We've found a dominated block, now see if it computes
6310 the busy expression and whether or not moving that
6311 expression to the "beginning" of that block is safe. */
6312 if (!TEST_BIT (antloc
[dominated
->index
], i
))
6315 /* Note if the expression would reach the dominated block
6316 unimpared if it was placed at the end of BB.
6318 Keep track of how many times this expression is hoistable
6319 from a dominated block into BB. */
6320 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
6324 /* If we found more than one hoistable occurrence of this
6325 expression, then note it in the bitmap of expressions to
6326 hoist. It makes no sense to hoist things which are computed
6327 in only one BB, and doing so tends to pessimize register
6328 allocation. One could increase this value to try harder
6329 to avoid any possible code expansion due to register
6330 allocation issues; however experiments have shown that
6331 the vast majority of hoistable expressions are only movable
6332 from two successors, so raising this threshhold is likely
6333 to nullify any benefit we get from code hoisting. */
6336 SET_BIT (hoist_exprs
[bb
->index
], i
);
6341 /* If we found nothing to hoist, then quit now. */
6348 /* Loop over all the hoistable expressions. */
6349 for (i
= 0; i
< hoist_exprs
[bb
->index
]->n_bits
; i
++)
6351 /* We want to insert the expression into BB only once, so
6352 note when we've inserted it. */
6353 insn_inserted_p
= 0;
6355 /* These tests should be the same as the tests above. */
6356 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
))
6358 /* We've found a potentially hoistable expression, now
6359 we look at every block BB dominates to see if it
6360 computes the expression. */
6361 for (j
= 0; j
< domby_len
; j
++)
6363 dominated
= domby
[j
];
6364 /* Ignore self dominance. */
6365 if (bb
== dominated
)
6368 /* We've found a dominated block, now see if it computes
6369 the busy expression and whether or not moving that
6370 expression to the "beginning" of that block is safe. */
6371 if (!TEST_BIT (antloc
[dominated
->index
], i
))
6374 /* The expression is computed in the dominated block and
6375 it would be safe to compute it at the start of the
6376 dominated block. Now we have to determine if the
6377 expression would reach the dominated block if it was
6378 placed at the end of BB. */
6379 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
6381 struct expr
*expr
= index_map
[i
];
6382 struct occr
*occr
= expr
->antic_occr
;
6386 /* Find the right occurrence of this expression. */
6387 while (BLOCK_FOR_INSN (occr
->insn
) != dominated
&& occr
)
6390 /* Should never happen. */
6396 set
= single_set (insn
);
6400 /* Create a pseudo-reg to store the result of reaching
6401 expressions into. Get the mode for the new pseudo
6402 from the mode of the original destination pseudo. */
6403 if (expr
->reaching_reg
== NULL
)
6405 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
6407 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
6409 occr
->deleted_p
= 1;
6410 if (!insn_inserted_p
)
6412 insert_insn_end_bb (index_map
[i
], bb
, 0);
6413 insn_inserted_p
= 1;
6425 /* Top level routine to perform one code hoisting (aka unification) pass
6427 Return nonzero if a change was made. */
6430 one_code_hoisting_pass ()
6434 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
6435 compute_hash_table (&expr_hash_table
);
6437 dump_hash_table (gcse_file
, "Code Hosting Expressions", &expr_hash_table
);
6439 if (expr_hash_table
.n_elems
> 0)
6441 alloc_code_hoist_mem (last_basic_block
, expr_hash_table
.n_elems
);
6442 compute_code_hoist_data ();
6444 free_code_hoist_mem ();
6447 free_hash_table (&expr_hash_table
);
6452 /* Here we provide the things required to do store motion towards
6453 the exit. In order for this to be effective, gcse also needed to
6454 be taught how to move a load when it is kill only by a store to itself.
6459 void foo(float scale)
6461 for (i=0; i<10; i++)
6465 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
6466 the load out since its live around the loop, and stored at the bottom
6469 The 'Load Motion' referred to and implemented in this file is
6470 an enhancement to gcse which when using edge based lcm, recognizes
6471 this situation and allows gcse to move the load out of the loop.
6473 Once gcse has hoisted the load, store motion can then push this
6474 load towards the exit, and we end up with no loads or stores of 'i'
6477 /* This will search the ldst list for a matching expression. If it
6478 doesn't find one, we create one and initialize it. */
6480 static struct ls_expr
*
6484 struct ls_expr
* ptr
;
6486 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6487 if (expr_equiv_p (ptr
->pattern
, x
))
6492 ptr
= (struct ls_expr
*) xmalloc (sizeof (struct ls_expr
));
6494 ptr
->next
= pre_ldst_mems
;
6497 ptr
->loads
= NULL_RTX
;
6498 ptr
->stores
= NULL_RTX
;
6499 ptr
->reaching_reg
= NULL_RTX
;
6502 ptr
->hash_index
= 0;
6503 pre_ldst_mems
= ptr
;
6509 /* Free up an individual ldst entry. */
6512 free_ldst_entry (ptr
)
6513 struct ls_expr
* ptr
;
6515 free_INSN_LIST_list (& ptr
->loads
);
6516 free_INSN_LIST_list (& ptr
->stores
);
6521 /* Free up all memory associated with the ldst list. */
6526 while (pre_ldst_mems
)
6528 struct ls_expr
* tmp
= pre_ldst_mems
;
6530 pre_ldst_mems
= pre_ldst_mems
->next
;
6532 free_ldst_entry (tmp
);
6535 pre_ldst_mems
= NULL
;
6538 /* Dump debugging info about the ldst list. */
6541 print_ldst_list (file
)
6544 struct ls_expr
* ptr
;
6546 fprintf (file
, "LDST list: \n");
6548 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6550 fprintf (file
, " Pattern (%3d): ", ptr
->index
);
6552 print_rtl (file
, ptr
->pattern
);
6554 fprintf (file
, "\n Loads : ");
6557 print_rtl (file
, ptr
->loads
);
6559 fprintf (file
, "(nil)");
6561 fprintf (file
, "\n Stores : ");
6564 print_rtl (file
, ptr
->stores
);
6566 fprintf (file
, "(nil)");
6568 fprintf (file
, "\n\n");
6571 fprintf (file
, "\n");
6574 /* Returns 1 if X is in the list of ldst only expressions. */
6576 static struct ls_expr
*
6577 find_rtx_in_ldst (x
)
6580 struct ls_expr
* ptr
;
6582 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
6583 if (expr_equiv_p (ptr
->pattern
, x
) && ! ptr
->invalid
)
6589 /* Assign each element of the list of mems a monotonically increasing value. */
6594 struct ls_expr
* ptr
;
6597 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
6603 /* Return first item in the list. */
6605 static inline struct ls_expr
*
6608 return pre_ldst_mems
;
6611 /* Return the next item in ther list after the specified one. */
6613 static inline struct ls_expr
*
6615 struct ls_expr
* ptr
;
6620 /* Load Motion for loads which only kill themselves. */
6622 /* Return true if x is a simple MEM operation, with no registers or
6623 side effects. These are the types of loads we consider for the
6624 ld_motion list, otherwise we let the usual aliasing take care of it. */
6630 if (GET_CODE (x
) != MEM
)
6633 if (MEM_VOLATILE_P (x
))
6636 if (GET_MODE (x
) == BLKmode
)
6639 if (!rtx_varies_p (XEXP (x
, 0), 0))
6645 /* Make sure there isn't a buried reference in this pattern anywhere.
6646 If there is, invalidate the entry for it since we're not capable
6647 of fixing it up just yet.. We have to be sure we know about ALL
6648 loads since the aliasing code will allow all entries in the
6649 ld_motion list to not-alias itself. If we miss a load, we will get
6650 the wrong value since gcse might common it and we won't know to
6654 invalidate_any_buried_refs (x
)
6659 struct ls_expr
* ptr
;
6661 /* Invalidate it in the list. */
6662 if (GET_CODE (x
) == MEM
&& simple_mem (x
))
6664 ptr
= ldst_entry (x
);
6668 /* Recursively process the insn. */
6669 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
6671 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0; i
--)
6674 invalidate_any_buried_refs (XEXP (x
, i
));
6675 else if (fmt
[i
] == 'E')
6676 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
6677 invalidate_any_buried_refs (XVECEXP (x
, i
, j
));
6681 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
6682 being defined as MEM loads and stores to symbols, with no
6683 side effects and no registers in the expression. If there are any
6684 uses/defs which don't match this criteria, it is invalidated and
6685 trimmed out later. */
6688 compute_ld_motion_mems ()
6690 struct ls_expr
* ptr
;
6694 pre_ldst_mems
= NULL
;
6698 for (insn
= bb
->head
;
6699 insn
&& insn
!= NEXT_INSN (bb
->end
);
6700 insn
= NEXT_INSN (insn
))
6702 if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i')
6704 if (GET_CODE (PATTERN (insn
)) == SET
)
6706 rtx src
= SET_SRC (PATTERN (insn
));
6707 rtx dest
= SET_DEST (PATTERN (insn
));
6709 /* Check for a simple LOAD... */
6710 if (GET_CODE (src
) == MEM
&& simple_mem (src
))
6712 ptr
= ldst_entry (src
);
6713 if (GET_CODE (dest
) == REG
)
6714 ptr
->loads
= alloc_INSN_LIST (insn
, ptr
->loads
);
6720 /* Make sure there isn't a buried load somewhere. */
6721 invalidate_any_buried_refs (src
);
6724 /* Check for stores. Don't worry about aliased ones, they
6725 will block any movement we might do later. We only care
6726 about this exact pattern since those are the only
6727 circumstance that we will ignore the aliasing info. */
6728 if (GET_CODE (dest
) == MEM
&& simple_mem (dest
))
6730 ptr
= ldst_entry (dest
);
6732 if (GET_CODE (src
) != MEM
6733 && GET_CODE (src
) != ASM_OPERANDS
)
6734 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
6740 invalidate_any_buried_refs (PATTERN (insn
));
6746 /* Remove any references that have been either invalidated or are not in the
6747 expression list for pre gcse. */
6750 trim_ld_motion_mems ()
6752 struct ls_expr
* last
= NULL
;
6753 struct ls_expr
* ptr
= first_ls_expr ();
6757 int del
= ptr
->invalid
;
6758 struct expr
* expr
= NULL
;
6760 /* Delete if entry has been made invalid. */
6766 /* Delete if we cannot find this mem in the expression list. */
6767 for (i
= 0; i
< expr_hash_table
.size
&& del
; i
++)
6769 for (expr
= expr_hash_table
.table
[i
];
6771 expr
= expr
->next_same_hash
)
6772 if (expr_equiv_p (expr
->expr
, ptr
->pattern
))
6784 last
->next
= ptr
->next
;
6785 free_ldst_entry (ptr
);
6790 pre_ldst_mems
= pre_ldst_mems
->next
;
6791 free_ldst_entry (ptr
);
6792 ptr
= pre_ldst_mems
;
6797 /* Set the expression field if we are keeping it. */
6804 /* Show the world what we've found. */
6805 if (gcse_file
&& pre_ldst_mems
!= NULL
)
6806 print_ldst_list (gcse_file
);
6809 /* This routine will take an expression which we are replacing with
6810 a reaching register, and update any stores that are needed if
6811 that expression is in the ld_motion list. Stores are updated by
6812 copying their SRC to the reaching register, and then storeing
6813 the reaching register into the store location. These keeps the
6814 correct value in the reaching register for the loads. */
6817 update_ld_motion_stores (expr
)
6820 struct ls_expr
* mem_ptr
;
6822 if ((mem_ptr
= find_rtx_in_ldst (expr
->expr
)))
6824 /* We can try to find just the REACHED stores, but is shouldn't
6825 matter to set the reaching reg everywhere... some might be
6826 dead and should be eliminated later. */
6828 /* We replace SET mem = expr with
6830 SET mem = reg , where reg is the
6831 reaching reg used in the load. */
6832 rtx list
= mem_ptr
->stores
;
6834 for ( ; list
!= NULL_RTX
; list
= XEXP (list
, 1))
6836 rtx insn
= XEXP (list
, 0);
6837 rtx pat
= PATTERN (insn
);
6838 rtx src
= SET_SRC (pat
);
6839 rtx reg
= expr
->reaching_reg
;
6842 /* If we've already copied it, continue. */
6843 if (expr
->reaching_reg
== src
)
6848 fprintf (gcse_file
, "PRE: store updated with reaching reg ");
6849 print_rtl (gcse_file
, expr
->reaching_reg
);
6850 fprintf (gcse_file
, ":\n ");
6851 print_inline_rtx (gcse_file
, insn
, 8);
6852 fprintf (gcse_file
, "\n");
6855 copy
= gen_move_insn ( reg
, SET_SRC (pat
));
6856 new = emit_insn_before (copy
, insn
);
6857 record_one_set (REGNO (reg
), new);
6858 SET_SRC (pat
) = reg
;
6860 /* un-recognize this pattern since it's probably different now. */
6861 INSN_CODE (insn
) = -1;
6862 gcse_create_count
++;
6867 /* Store motion code. */
6869 /* This is used to communicate the target bitvector we want to use in the
6870 reg_set_info routine when called via the note_stores mechanism. */
6871 static sbitmap
* regvec
;
6873 /* Used in computing the reverse edge graph bit vectors. */
6874 static sbitmap
* st_antloc
;
6876 /* Global holding the number of store expressions we are dealing with. */
6877 static int num_stores
;
6879 /* Checks to set if we need to mark a register set. Called from note_stores. */
6882 reg_set_info (dest
, setter
, data
)
6883 rtx dest
, setter ATTRIBUTE_UNUSED
;
6884 void * data ATTRIBUTE_UNUSED
;
6886 if (GET_CODE (dest
) == SUBREG
)
6887 dest
= SUBREG_REG (dest
);
6889 if (GET_CODE (dest
) == REG
)
6890 SET_BIT (*regvec
, REGNO (dest
));
6893 /* Return nonzero if the register operands of expression X are killed
6894 anywhere in basic block BB. */
6897 store_ops_ok (x
, bb
)
6905 /* Repeat is used to turn tail-recursion into iteration. */
6911 code
= GET_CODE (x
);
6915 /* If a reg has changed after us in this
6916 block, the operand has been killed. */
6917 return TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
));
6945 i
= GET_RTX_LENGTH (code
) - 1;
6946 fmt
= GET_RTX_FORMAT (code
);
6952 rtx tem
= XEXP (x
, i
);
6954 /* If we are about to do the last recursive call
6955 needed at this level, change it into iteration.
6956 This function is called enough to be worth it. */
6963 if (! store_ops_ok (tem
, bb
))
6966 else if (fmt
[i
] == 'E')
6970 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
6972 if (! store_ops_ok (XVECEXP (x
, i
, j
), bb
))
6981 /* Determine whether insn is MEM store pattern that we will consider moving. */
6984 find_moveable_store (insn
)
6987 struct ls_expr
* ptr
;
6988 rtx dest
= PATTERN (insn
);
6990 if (GET_CODE (dest
) != SET
6991 || GET_CODE (SET_SRC (dest
)) == ASM_OPERANDS
)
6994 dest
= SET_DEST (dest
);
6996 if (GET_CODE (dest
) != MEM
|| MEM_VOLATILE_P (dest
)
6997 || GET_MODE (dest
) == BLKmode
)
7000 if (GET_CODE (XEXP (dest
, 0)) != SYMBOL_REF
)
7003 if (rtx_varies_p (XEXP (dest
, 0), 0))
7006 ptr
= ldst_entry (dest
);
7007 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
7010 /* Perform store motion. Much like gcse, except we move expressions the
7011 other way by looking at the flowgraph in reverse. */
7014 compute_store_table ()
7021 max_gcse_regno
= max_reg_num ();
7023 reg_set_in_block
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
,
7025 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
7028 /* Find all the stores we care about. */
7031 regvec
= & (reg_set_in_block
[bb
->index
]);
7032 for (insn
= bb
->end
;
7033 insn
&& insn
!= PREV_INSN (bb
->end
);
7034 insn
= PREV_INSN (insn
))
7036 /* Ignore anything that is not a normal insn. */
7037 if (! INSN_P (insn
))
7040 if (GET_CODE (insn
) == CALL_INSN
)
7042 bool clobbers_all
= false;
7043 #ifdef NON_SAVING_SETJMP
7044 if (NON_SAVING_SETJMP
7045 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
7046 clobbers_all
= true;
7049 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
7051 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
7052 SET_BIT (reg_set_in_block
[bb
->index
], regno
);
7055 pat
= PATTERN (insn
);
7056 note_stores (pat
, reg_set_info
, NULL
);
7058 /* Now that we've marked regs, look for stores. */
7059 if (GET_CODE (pat
) == SET
)
7060 find_moveable_store (insn
);
7064 ret
= enumerate_ldsts ();
7068 fprintf (gcse_file
, "Store Motion Expressions.\n");
7069 print_ldst_list (gcse_file
);
7075 /* Check to see if the load X is aliased with STORE_PATTERN. */
7078 load_kills_store (x
, store_pattern
)
7079 rtx x
, store_pattern
;
7081 if (true_dependence (x
, GET_MODE (x
), store_pattern
, rtx_addr_varies_p
))
7086 /* Go through the entire insn X, looking for any loads which might alias
7087 STORE_PATTERN. Return 1 if found. */
7090 find_loads (x
, store_pattern
)
7091 rtx x
, store_pattern
;
7100 if (GET_CODE (x
) == SET
)
7103 if (GET_CODE (x
) == MEM
)
7105 if (load_kills_store (x
, store_pattern
))
7109 /* Recursively process the insn. */
7110 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
7112 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0 && !ret
; i
--)
7115 ret
|= find_loads (XEXP (x
, i
), store_pattern
);
7116 else if (fmt
[i
] == 'E')
7117 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
7118 ret
|= find_loads (XVECEXP (x
, i
, j
), store_pattern
);
7123 /* Check if INSN kills the store pattern X (is aliased with it).
7124 Return 1 if it it does. */
7127 store_killed_in_insn (x
, insn
)
7130 if (GET_RTX_CLASS (GET_CODE (insn
)) != 'i')
7133 if (GET_CODE (insn
) == CALL_INSN
)
7135 /* A normal or pure call might read from pattern,
7136 but a const call will not. */
7137 return ! CONST_OR_PURE_CALL_P (insn
) || pure_call_p (insn
);
7140 if (GET_CODE (PATTERN (insn
)) == SET
)
7142 rtx pat
= PATTERN (insn
);
7143 /* Check for memory stores to aliased objects. */
7144 if (GET_CODE (SET_DEST (pat
)) == MEM
&& !expr_equiv_p (SET_DEST (pat
), x
))
7145 /* pretend its a load and check for aliasing. */
7146 if (find_loads (SET_DEST (pat
), x
))
7148 return find_loads (SET_SRC (pat
), x
);
7151 return find_loads (PATTERN (insn
), x
);
7154 /* Returns 1 if the expression X is loaded or clobbered on or after INSN
7155 within basic block BB. */
7158 store_killed_after (x
, insn
, bb
)
7167 /* Check if the register operands of the store are OK in this block.
7168 Note that if registers are changed ANYWHERE in the block, we'll
7169 decide we can't move it, regardless of whether it changed above
7170 or below the store. This could be improved by checking the register
7171 operands while looking for aliasing in each insn. */
7172 if (!store_ops_ok (XEXP (x
, 0), bb
))
7175 for ( ; insn
&& insn
!= NEXT_INSN (last
); insn
= NEXT_INSN (insn
))
7176 if (store_killed_in_insn (x
, insn
))
7182 /* Returns 1 if the expression X is loaded or clobbered on or before INSN
7183 within basic block BB. */
7185 store_killed_before (x
, insn
, bb
)
7189 rtx first
= bb
->head
;
7192 return store_killed_in_insn (x
, insn
);
7194 /* Check if the register operands of the store are OK in this block.
7195 Note that if registers are changed ANYWHERE in the block, we'll
7196 decide we can't move it, regardless of whether it changed above
7197 or below the store. This could be improved by checking the register
7198 operands while looking for aliasing in each insn. */
7199 if (!store_ops_ok (XEXP (x
, 0), bb
))
7202 for ( ; insn
&& insn
!= PREV_INSN (first
); insn
= PREV_INSN (insn
))
7203 if (store_killed_in_insn (x
, insn
))
7209 #define ANTIC_STORE_LIST(x) ((x)->loads)
7210 #define AVAIL_STORE_LIST(x) ((x)->stores)
7212 /* Given the table of available store insns at the end of blocks,
7213 determine which ones are not killed by aliasing, and generate
7214 the appropriate vectors for gen and killed. */
7216 build_store_vectors ()
7220 struct ls_expr
* ptr
;
7222 /* Build the gen_vector. This is any store in the table which is not killed
7223 by aliasing later in its block. */
7224 ae_gen
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7225 sbitmap_vector_zero (ae_gen
, last_basic_block
);
7227 st_antloc
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7228 sbitmap_vector_zero (st_antloc
, last_basic_block
);
7230 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7232 /* Put all the stores into either the antic list, or the avail list,
7234 rtx store_list
= ptr
->stores
;
7235 ptr
->stores
= NULL_RTX
;
7237 for (st
= store_list
; st
!= NULL
; st
= XEXP (st
, 1))
7239 insn
= XEXP (st
, 0);
7240 bb
= BLOCK_FOR_INSN (insn
);
7242 if (!store_killed_after (ptr
->pattern
, insn
, bb
))
7244 /* If we've already seen an available expression in this block,
7245 we can delete the one we saw already (It occurs earlier in
7246 the block), and replace it with this one). We'll copy the
7247 old SRC expression to an unused register in case there
7248 are any side effects. */
7249 if (TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
7251 /* Find previous store. */
7253 for (st
= AVAIL_STORE_LIST (ptr
); st
; st
= XEXP (st
, 1))
7254 if (BLOCK_FOR_INSN (XEXP (st
, 0)) == bb
)
7258 rtx r
= gen_reg_rtx (GET_MODE (ptr
->pattern
));
7260 fprintf (gcse_file
, "Removing redundant store:\n");
7261 replace_store_insn (r
, XEXP (st
, 0), bb
);
7262 XEXP (st
, 0) = insn
;
7266 SET_BIT (ae_gen
[bb
->index
], ptr
->index
);
7267 AVAIL_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
,
7268 AVAIL_STORE_LIST (ptr
));
7271 if (!store_killed_before (ptr
->pattern
, insn
, bb
))
7273 SET_BIT (st_antloc
[BLOCK_NUM (insn
)], ptr
->index
);
7274 ANTIC_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
,
7275 ANTIC_STORE_LIST (ptr
));
7279 /* Free the original list of store insns. */
7280 free_INSN_LIST_list (&store_list
);
7283 ae_kill
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7284 sbitmap_vector_zero (ae_kill
, last_basic_block
);
7286 transp
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7287 sbitmap_vector_zero (transp
, last_basic_block
);
7289 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7292 if (store_killed_after (ptr
->pattern
, b
->head
, b
))
7294 /* The anticipatable expression is not killed if it's gen'd. */
7296 We leave this check out for now. If we have a code sequence
7297 in a block which looks like:
7301 We should flag this as having an ANTIC expression, NOT
7302 transparent, NOT killed, and AVAIL.
7303 Unfortunately, since we haven't re-written all loads to
7304 use the reaching reg, we'll end up doing an incorrect
7305 Load in the middle here if we push the store down. It happens in
7306 gcc.c-torture/execute/960311-1.c with -O3
7307 If we always kill it in this case, we'll sometimes do
7308 unnecessary work, but it shouldn't actually hurt anything.
7309 if (!TEST_BIT (ae_gen[b], ptr->index)). */
7310 SET_BIT (ae_kill
[b
->index
], ptr
->index
);
7313 SET_BIT (transp
[b
->index
], ptr
->index
);
7316 /* Any block with no exits calls some non-returning function, so
7317 we better mark the store killed here, or we might not store to
7318 it at all. If we knew it was abort, we wouldn't have to store,
7319 but we don't know that for sure. */
7322 fprintf (gcse_file
, "ST_avail and ST_antic (shown under loads..)\n");
7323 print_ldst_list (gcse_file
);
7324 dump_sbitmap_vector (gcse_file
, "st_antloc", "", st_antloc
, last_basic_block
);
7325 dump_sbitmap_vector (gcse_file
, "st_kill", "", ae_kill
, last_basic_block
);
7326 dump_sbitmap_vector (gcse_file
, "Transpt", "", transp
, last_basic_block
);
7327 dump_sbitmap_vector (gcse_file
, "st_avloc", "", ae_gen
, last_basic_block
);
7331 /* Insert an instruction at the beginning of a basic block, and update
7332 the BLOCK_HEAD if needed. */
7335 insert_insn_start_bb (insn
, bb
)
7339 /* Insert at start of successor block. */
7340 rtx prev
= PREV_INSN (bb
->head
);
7341 rtx before
= bb
->head
;
7344 if (GET_CODE (before
) != CODE_LABEL
7345 && (GET_CODE (before
) != NOTE
7346 || NOTE_LINE_NUMBER (before
) != NOTE_INSN_BASIC_BLOCK
))
7349 if (prev
== bb
->end
)
7351 before
= NEXT_INSN (before
);
7354 insn
= emit_insn_after (insn
, prev
);
7358 fprintf (gcse_file
, "STORE_MOTION insert store at start of BB %d:\n",
7360 print_inline_rtx (gcse_file
, insn
, 6);
7361 fprintf (gcse_file
, "\n");
7365 /* This routine will insert a store on an edge. EXPR is the ldst entry for
7366 the memory reference, and E is the edge to insert it on. Returns nonzero
7367 if an edge insertion was performed. */
7370 insert_store (expr
, e
)
7371 struct ls_expr
* expr
;
7378 /* We did all the deleted before this insert, so if we didn't delete a
7379 store, then we haven't set the reaching reg yet either. */
7380 if (expr
->reaching_reg
== NULL_RTX
)
7383 reg
= expr
->reaching_reg
;
7384 insn
= gen_move_insn (expr
->pattern
, reg
);
7386 /* If we are inserting this expression on ALL predecessor edges of a BB,
7387 insert it at the start of the BB, and reset the insert bits on the other
7388 edges so we don't try to insert it on the other edges. */
7390 for (tmp
= e
->dest
->pred
; tmp
; tmp
= tmp
->pred_next
)
7392 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
7393 if (index
== EDGE_INDEX_NO_EDGE
)
7395 if (! TEST_BIT (pre_insert_map
[index
], expr
->index
))
7399 /* If tmp is NULL, we found an insertion on every edge, blank the
7400 insertion vector for these edges, and insert at the start of the BB. */
7401 if (!tmp
&& bb
!= EXIT_BLOCK_PTR
)
7403 for (tmp
= e
->dest
->pred
; tmp
; tmp
= tmp
->pred_next
)
7405 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
7406 RESET_BIT (pre_insert_map
[index
], expr
->index
);
7408 insert_insn_start_bb (insn
, bb
);
7412 /* We can't insert on this edge, so we'll insert at the head of the
7413 successors block. See Morgan, sec 10.5. */
7414 if ((e
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
7416 insert_insn_start_bb (insn
, bb
);
7420 insert_insn_on_edge (insn
, e
);
7424 fprintf (gcse_file
, "STORE_MOTION insert insn on edge (%d, %d):\n",
7425 e
->src
->index
, e
->dest
->index
);
7426 print_inline_rtx (gcse_file
, insn
, 6);
7427 fprintf (gcse_file
, "\n");
7433 /* This routine will replace a store with a SET to a specified register. */
7436 replace_store_insn (reg
, del
, bb
)
7442 insn
= gen_move_insn (reg
, SET_SRC (PATTERN (del
)));
7443 insn
= emit_insn_after (insn
, del
);
7448 "STORE_MOTION delete insn in BB %d:\n ", bb
->index
);
7449 print_inline_rtx (gcse_file
, del
, 6);
7450 fprintf (gcse_file
, "\nSTORE MOTION replaced with insn:\n ");
7451 print_inline_rtx (gcse_file
, insn
, 6);
7452 fprintf (gcse_file
, "\n");
7459 /* Delete a store, but copy the value that would have been stored into
7460 the reaching_reg for later storing. */
7463 delete_store (expr
, bb
)
7464 struct ls_expr
* expr
;
7469 if (expr
->reaching_reg
== NULL_RTX
)
7470 expr
->reaching_reg
= gen_reg_rtx (GET_MODE (expr
->pattern
));
7473 /* If there is more than 1 store, the earlier ones will be dead,
7474 but it doesn't hurt to replace them here. */
7475 reg
= expr
->reaching_reg
;
7477 for (i
= AVAIL_STORE_LIST (expr
); i
; i
= XEXP (i
, 1))
7480 if (BLOCK_FOR_INSN (del
) == bb
)
7482 /* We know there is only one since we deleted redundant
7483 ones during the available computation. */
7484 replace_store_insn (reg
, del
, bb
);
7490 /* Free memory used by store motion. */
7493 free_store_memory ()
7498 sbitmap_vector_free (ae_gen
);
7500 sbitmap_vector_free (ae_kill
);
7502 sbitmap_vector_free (transp
);
7504 sbitmap_vector_free (st_antloc
);
7506 sbitmap_vector_free (pre_insert_map
);
7508 sbitmap_vector_free (pre_delete_map
);
7509 if (reg_set_in_block
)
7510 sbitmap_vector_free (reg_set_in_block
);
7512 ae_gen
= ae_kill
= transp
= st_antloc
= NULL
;
7513 pre_insert_map
= pre_delete_map
= reg_set_in_block
= NULL
;
7516 /* Perform store motion. Much like gcse, except we move expressions the
7517 other way by looking at the flowgraph in reverse. */
7524 struct ls_expr
* ptr
;
7525 int update_flow
= 0;
7529 fprintf (gcse_file
, "before store motion\n");
7530 print_rtl (gcse_file
, get_insns ());
7534 init_alias_analysis ();
7536 /* Find all the stores that are live to the end of their block. */
7537 num_stores
= compute_store_table ();
7538 if (num_stores
== 0)
7540 sbitmap_vector_free (reg_set_in_block
);
7541 end_alias_analysis ();
7545 /* Now compute whats actually available to move. */
7546 add_noreturn_fake_exit_edges ();
7547 build_store_vectors ();
7549 edge_list
= pre_edge_rev_lcm (gcse_file
, num_stores
, transp
, ae_gen
,
7550 st_antloc
, ae_kill
, &pre_insert_map
,
7553 /* Now we want to insert the new stores which are going to be needed. */
7554 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7557 if (TEST_BIT (pre_delete_map
[bb
->index
], ptr
->index
))
7558 delete_store (ptr
, bb
);
7560 for (x
= 0; x
< NUM_EDGES (edge_list
); x
++)
7561 if (TEST_BIT (pre_insert_map
[x
], ptr
->index
))
7562 update_flow
|= insert_store (ptr
, INDEX_EDGE (edge_list
, x
));
7566 commit_edge_insertions ();
7568 free_store_memory ();
7569 free_edge_list (edge_list
);
7570 remove_fake_edges ();
7571 end_alias_analysis ();
7575 /* Entry point for jump bypassing optimization pass. */
7583 /* We do not construct an accurate cfg in functions which call
7584 setjmp, so just punt to be safe. */
7585 if (current_function_calls_setjmp
)
7588 /* For calling dump_foo fns from gdb. */
7589 debug_stderr
= stderr
;
7592 /* Identify the basic block information for this function, including
7593 successors and predecessors. */
7594 max_gcse_regno
= max_reg_num ();
7597 dump_flow_info (file
);
7599 /* Return if there's nothing to do. */
7600 if (n_basic_blocks
<= 1)
7603 /* Trying to perform global optimizations on flow graphs which have
7604 a high connectivity will take a long time and is unlikely to be
7605 particularly useful.
7607 In normal circumstances a cfg should have about twice as many edges
7608 as blocks. But we do not want to punish small functions which have
7609 a couple switch statements. So we require a relatively large number
7610 of basic blocks and the ratio of edges to blocks to be high. */
7611 if (n_basic_blocks
> 1000 && n_edges
/ n_basic_blocks
>= 20)
7613 if (warn_disabled_optimization
)
7614 warning ("BYPASS disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
7615 n_basic_blocks
, n_edges
/ n_basic_blocks
);
7619 /* If allocating memory for the cprop bitmap would take up too much
7620 storage it's better just to disable the optimization. */
7622 * SBITMAP_SET_SIZE (max_gcse_regno
)
7623 * sizeof (SBITMAP_ELT_TYPE
)) > MAX_GCSE_MEMORY
)
7625 if (warn_disabled_optimization
)
7626 warning ("GCSE disabled: %d basic blocks and %d registers",
7627 n_basic_blocks
, max_gcse_regno
);
7632 /* See what modes support reg/reg copy operations. */
7633 if (! can_copy_init_p
)
7635 compute_can_copy ();
7636 can_copy_init_p
= 1;
7639 gcc_obstack_init (&gcse_obstack
);
7642 /* We need alias. */
7643 init_alias_analysis ();
7645 /* Record where pseudo-registers are set. This data is kept accurate
7646 during each pass. ??? We could also record hard-reg information here
7647 [since it's unchanging], however it is currently done during hash table
7650 It may be tempting to compute MEM set information here too, but MEM sets
7651 will be subject to code motion one day and thus we need to compute
7652 information about memory sets when we build the hash tables. */
7654 alloc_reg_set_mem (max_gcse_regno
);
7655 compute_sets (get_insns ());
7657 max_gcse_regno
= max_reg_num ();
7658 alloc_gcse_mem (get_insns ());
7659 changed
= one_cprop_pass (1, 1, 1);
7664 fprintf (file
, "BYPASS of %s: %d basic blocks, ",
7665 current_function_name
, n_basic_blocks
);
7666 fprintf (file
, "%d bytes\n\n", bytes_used
);
7669 obstack_free (&gcse_obstack
, NULL
);
7670 free_reg_set_mem ();
7672 /* We are finished with alias. */
7673 end_alias_analysis ();
7674 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
7679 #include "gt-gcse.h"