1 /* Global common subexpression elimination/Partial redundancy elimination
2 and global constant/copy propagation for GNU compiler.
3 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
24 - reordering of memory allocation and freeing to be more space efficient
25 - do rough calc of how many regs are needed in each block, and a rough
26 calc of how many regs are available in each class and use that to
27 throttle back the code in cases where RTX_COST is minimal.
28 - a store to the same address as a load does not kill the load if the
29 source of the store is also the destination of the load. Handling this
30 allows more load motion, particularly out of loops.
31 - ability to realloc sbitmap vectors would allow one initial computation
32 of reg_set_in_block with only subsequent additions, rather than
33 recomputing it for each pass
37 /* References searched while implementing this.
39 Compilers Principles, Techniques and Tools
43 Global Optimization by Suppression of Partial Redundancies
45 communications of the acm, Vol. 22, Num. 2, Feb. 1979
47 A Portable Machine-Independent Global Optimizer - Design and Measurements
49 Stanford Ph.D. thesis, Dec. 1983
51 A Fast Algorithm for Code Movement Optimization
53 SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988
55 A Solution to a Problem with Morel and Renvoise's
56 Global Optimization by Suppression of Partial Redundancies
57 K-H Drechsler, M.P. Stadel
58 ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988
60 Practical Adaptation of the Global Optimization
61 Algorithm of Morel and Renvoise
63 ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991
65 Efficiently Computing Static Single Assignment Form and the Control
67 R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck
68 ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991
71 J. Knoop, O. Ruthing, B. Steffen
72 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
74 What's In a Region? Or Computing Control Dependence Regions in Near-Linear
75 Time for Reducible Flow Control
77 ACM Letters on Programming Languages and Systems,
78 Vol. 2, Num. 1-4, Mar-Dec 1993
80 An Efficient Representation for Sparse Sets
81 Preston Briggs, Linda Torczon
82 ACM Letters on Programming Languages and Systems,
83 Vol. 2, Num. 1-4, Mar-Dec 1993
85 A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion
86 K-H Drechsler, M.P. Stadel
87 ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993
89 Partial Dead Code Elimination
90 J. Knoop, O. Ruthing, B. Steffen
91 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
93 Effective Partial Redundancy Elimination
94 P. Briggs, K.D. Cooper
95 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
97 The Program Structure Tree: Computing Control Regions in Linear Time
98 R. Johnson, D. Pearson, K. Pingali
99 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
101 Optimal Code Motion: Theory and Practice
102 J. Knoop, O. Ruthing, B. Steffen
103 ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994
105 The power of assignment motion
106 J. Knoop, O. Ruthing, B. Steffen
107 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
109 Global code motion / global value numbering
111 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
113 Value Driven Redundancy Elimination
115 Rice University Ph.D. thesis, Apr. 1996
119 Massively Scalar Compiler Project, Rice University, Sep. 1996
121 High Performance Compilers for Parallel Computing
125 Advanced Compiler Design and Implementation
127 Morgan Kaufmann, 1997
129 Building an Optimizing Compiler
133 People wishing to speed up the code here should read:
134 Elimination Algorithms for Data Flow Analysis
135 B.G. Ryder, M.C. Paull
136 ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986
138 How to Analyze Large Programs Efficiently and Informatively
139 D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck
140 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
142 People wishing to do something different can find various possibilities
143 in the above papers and elsewhere.
148 #include "coretypes.h"
155 #include "hard-reg-set.h"
158 #include "insn-config.h"
160 #include "basic-block.h"
162 #include "function.h"
171 /* Propagate flow information through back edges and thus enable PRE's
172 moving loop invariant calculations out of loops.
174 Originally this tended to create worse overall code, but several
175 improvements during the development of PRE seem to have made following
176 back edges generally a win.
178 Note much of the loop invariant code motion done here would normally
179 be done by loop.c, which has more heuristics for when to move invariants
180 out of loops. At some point we might need to move some of those
181 heuristics into gcse.c. */
183 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
184 are a superset of those done by GCSE.
186 We perform the following steps:
188 1) Compute basic block information.
190 2) Compute table of places where registers are set.
192 3) Perform copy/constant propagation.
194 4) Perform global cse.
196 5) Perform another pass of copy/constant propagation.
198 Two passes of copy/constant propagation are done because the first one
199 enables more GCSE and the second one helps to clean up the copies that
200 GCSE creates. This is needed more for PRE than for Classic because Classic
201 GCSE will try to use an existing register containing the common
202 subexpression rather than create a new one. This is harder to do for PRE
203 because of the code motion (which Classic GCSE doesn't do).
205 Expressions we are interested in GCSE-ing are of the form
206 (set (pseudo-reg) (expression)).
207 Function want_to_gcse_p says what these are.
209 PRE handles moving invariant expressions out of loops (by treating them as
210 partially redundant).
212 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
213 assignment) based GVN (global value numbering). L. T. Simpson's paper
214 (Rice University) on value numbering is a useful reference for this.
216 **********************
218 We used to support multiple passes but there are diminishing returns in
219 doing so. The first pass usually makes 90% of the changes that are doable.
220 A second pass can make a few more changes made possible by the first pass.
221 Experiments show any further passes don't make enough changes to justify
224 A study of spec92 using an unlimited number of passes:
225 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
226 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
227 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
229 It was found doing copy propagation between each pass enables further
232 PRE is quite expensive in complicated functions because the DFA can take
233 awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can
234 be modified if one wants to experiment.
236 **********************
238 The steps for PRE are:
240 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
242 2) Perform the data flow analysis for PRE.
244 3) Delete the redundant instructions
246 4) Insert the required copies [if any] that make the partially
247 redundant instructions fully redundant.
249 5) For other reaching expressions, insert an instruction to copy the value
250 to a newly created pseudo that will reach the redundant instruction.
252 The deletion is done first so that when we do insertions we
253 know which pseudo reg to use.
255 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
256 argue it is not. The number of iterations for the algorithm to converge
257 is typically 2-4 so I don't view it as that expensive (relatively speaking).
259 PRE GCSE depends heavily on the second CSE pass to clean up the copies
260 we create. To make an expression reach the place where it's redundant,
261 the result of the expression is copied to a new register, and the redundant
262 expression is deleted by replacing it with this new register. Classic GCSE
263 doesn't have this problem as much as it computes the reaching defs of
264 each register in each block and thus can try to use an existing register.
266 **********************
268 A fair bit of simplicity is created by creating small functions for simple
269 tasks, even when the function is only called in one place. This may
270 measurably slow things down [or may not] by creating more function call
271 overhead than is necessary. The source is laid out so that it's trivial
272 to make the affected functions inline so that one can measure what speed
273 up, if any, can be achieved, and maybe later when things settle things can
276 Help stamp out big monolithic functions! */
278 /* GCSE global vars. */
281 static FILE *gcse_file
;
283 /* Note whether or not we should run jump optimization after gcse. We
284 want to do this for two cases.
286 * If we changed any jumps via cprop.
288 * If we added any labels via edge splitting. */
290 static int run_jump_opt_after_gcse
;
292 /* Bitmaps are normally not included in debugging dumps.
293 However it's useful to be able to print them from GDB.
294 We could create special functions for this, but it's simpler to
295 just allow passing stderr to the dump_foo fns. Since stderr can
296 be a macro, we store a copy here. */
297 static FILE *debug_stderr
;
299 /* An obstack for our working variables. */
300 static struct obstack gcse_obstack
;
302 struct reg_use
{rtx reg_rtx
; };
304 /* Hash table of expressions. */
308 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
310 /* Index in the available expression bitmaps. */
312 /* Next entry with the same hash. */
313 struct expr
*next_same_hash
;
314 /* List of anticipatable occurrences in basic blocks in the function.
315 An "anticipatable occurrence" is one that is the first occurrence in the
316 basic block, the operands are not modified in the basic block prior
317 to the occurrence and the output is not used between the start of
318 the block and the occurrence. */
319 struct occr
*antic_occr
;
320 /* List of available occurrence in basic blocks in the function.
321 An "available occurrence" is one that is the last occurrence in the
322 basic block and the operands are not modified by following statements in
323 the basic block [including this insn]. */
324 struct occr
*avail_occr
;
325 /* Non-null if the computation is PRE redundant.
326 The value is the newly created pseudo-reg to record a copy of the
327 expression in all the places that reach the redundant copy. */
331 /* Occurrence of an expression.
332 There is one per basic block. If a pattern appears more than once the
333 last appearance is used [or first for anticipatable expressions]. */
337 /* Next occurrence of this expression. */
339 /* The insn that computes the expression. */
341 /* Nonzero if this [anticipatable] occurrence has been deleted. */
343 /* Nonzero if this [available] occurrence has been copied to
345 /* ??? This is mutually exclusive with deleted_p, so they could share
350 /* Expression and copy propagation hash tables.
351 Each hash table is an array of buckets.
352 ??? It is known that if it were an array of entries, structure elements
353 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
354 not clear whether in the final analysis a sufficient amount of memory would
355 be saved as the size of the available expression bitmaps would be larger
356 [one could build a mapping table without holes afterwards though].
357 Someday I'll perform the computation and figure it out. */
362 This is an array of `expr_hash_table_size' elements. */
365 /* Size of the hash table, in elements. */
368 /* Number of hash table elements. */
369 unsigned int n_elems
;
371 /* Whether the table is expression of copy propagation one. */
375 /* Expression hash table. */
376 static struct hash_table expr_hash_table
;
378 /* Copy propagation hash table. */
379 static struct hash_table set_hash_table
;
381 /* Mapping of uids to cuids.
382 Only real insns get cuids. */
383 static int *uid_cuid
;
385 /* Highest UID in UID_CUID. */
388 /* Get the cuid of an insn. */
389 #ifdef ENABLE_CHECKING
390 #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
392 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
395 /* Number of cuids. */
398 /* Mapping of cuids to insns. */
399 static rtx
*cuid_insn
;
401 /* Get insn from cuid. */
402 #define CUID_INSN(CUID) (cuid_insn[CUID])
404 /* Maximum register number in function prior to doing gcse + 1.
405 Registers created during this pass have regno >= max_gcse_regno.
406 This is named with "gcse" to not collide with global of same name. */
407 static unsigned int max_gcse_regno
;
409 /* Table of registers that are modified.
411 For each register, each element is a list of places where the pseudo-reg
414 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
415 requires knowledge of which blocks kill which regs [and thus could use
416 a bitmap instead of the lists `reg_set_table' uses].
418 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
419 num-regs) [however perhaps it may be useful to keep the data as is]. One
420 advantage of recording things this way is that `reg_set_table' is fairly
421 sparse with respect to pseudo regs but for hard regs could be fairly dense
422 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
423 up functions like compute_transp since in the case of pseudo-regs we only
424 need to iterate over the number of times a pseudo-reg is set, not over the
425 number of basic blocks [clearly there is a bit of a slow down in the cases
426 where a pseudo is set more than once in a block, however it is believed
427 that the net effect is to speed things up]. This isn't done for hard-regs
428 because recording call-clobbered hard-regs in `reg_set_table' at each
429 function call can consume a fair bit of memory, and iterating over
430 hard-regs stored this way in compute_transp will be more expensive. */
432 typedef struct reg_set
434 /* The next setting of this register. */
435 struct reg_set
*next
;
436 /* The insn where it was set. */
440 static reg_set
**reg_set_table
;
442 /* Size of `reg_set_table'.
443 The table starts out at max_gcse_regno + slop, and is enlarged as
445 static int reg_set_table_size
;
447 /* Amount to grow `reg_set_table' by when it's full. */
448 #define REG_SET_TABLE_SLOP 100
450 /* This is a list of expressions which are MEMs and will be used by load
452 Load motion tracks MEMs which aren't killed by
453 anything except itself. (ie, loads and stores to a single location).
454 We can then allow movement of these MEM refs with a little special
455 allowance. (all stores copy the same value to the reaching reg used
456 for the loads). This means all values used to store into memory must have
457 no side effects so we can re-issue the setter value.
458 Store Motion uses this structure as an expression table to track stores
459 which look interesting, and might be moveable towards the exit block. */
463 struct expr
* expr
; /* Gcse expression reference for LM. */
464 rtx pattern
; /* Pattern of this mem. */
465 rtx pattern_regs
; /* List of registers mentioned by the mem. */
466 rtx loads
; /* INSN list of loads seen. */
467 rtx stores
; /* INSN list of stores seen. */
468 struct ls_expr
* next
; /* Next in the list. */
469 int invalid
; /* Invalid for some reason. */
470 int index
; /* If it maps to a bitmap index. */
471 int hash_index
; /* Index when in a hash table. */
472 rtx reaching_reg
; /* Register to use when re-writing. */
475 /* Array of implicit set patterns indexed by basic block index. */
476 static rtx
*implicit_sets
;
478 /* Head of the list of load/store memory refs. */
479 static struct ls_expr
* pre_ldst_mems
= NULL
;
481 /* Bitmap containing one bit for each register in the program.
482 Used when performing GCSE to track which registers have been set since
483 the start of the basic block. */
484 static regset reg_set_bitmap
;
486 /* For each block, a bitmap of registers set in the block.
487 This is used by expr_killed_p and compute_transp.
488 It is computed during hash table computation and not by compute_sets
489 as it includes registers added since the last pass (or between cprop and
490 gcse) and it's currently not easy to realloc sbitmap vectors. */
491 static sbitmap
*reg_set_in_block
;
493 /* Array, indexed by basic block number for a list of insns which modify
494 memory within that block. */
495 static rtx
* modify_mem_list
;
496 bitmap modify_mem_list_set
;
498 /* This array parallels modify_mem_list, but is kept canonicalized. */
499 static rtx
* canon_modify_mem_list
;
500 bitmap canon_modify_mem_list_set
;
501 /* Various variables for statistics gathering. */
503 /* Memory used in a pass.
504 This isn't intended to be absolutely precise. Its intent is only
505 to keep an eye on memory usage. */
506 static int bytes_used
;
508 /* GCSE substitutions made. */
509 static int gcse_subst_count
;
510 /* Number of copy instructions created. */
511 static int gcse_create_count
;
512 /* Number of constants propagated. */
513 static int const_prop_count
;
514 /* Number of copys propagated. */
515 static int copy_prop_count
;
517 /* These variables are used by classic GCSE.
518 Normally they'd be defined a bit later, but `rd_gen' needs to
519 be declared sooner. */
521 /* Each block has a bitmap of each type.
522 The length of each blocks bitmap is:
524 max_cuid - for reaching definitions
525 n_exprs - for available expressions
527 Thus we view the bitmaps as 2 dimensional arrays. i.e.
528 rd_kill[block_num][cuid_num]
529 ae_kill[block_num][expr_num] */
531 /* For reaching defs */
532 static sbitmap
*rd_kill
, *rd_gen
, *reaching_defs
, *rd_out
;
534 /* for available exprs */
535 static sbitmap
*ae_kill
, *ae_gen
, *ae_in
, *ae_out
;
537 /* Objects of this type are passed around by the null-pointer check
539 struct null_pointer_info
541 /* The basic block being processed. */
542 basic_block current_block
;
543 /* The first register to be handled in this pass. */
544 unsigned int min_reg
;
545 /* One greater than the last register to be handled in this pass. */
546 unsigned int max_reg
;
547 sbitmap
*nonnull_local
;
548 sbitmap
*nonnull_killed
;
551 static void compute_can_copy
PARAMS ((void));
552 static char *gmalloc
PARAMS ((unsigned int));
553 static char *grealloc
PARAMS ((char *, unsigned int));
554 static char *gcse_alloc
PARAMS ((unsigned long));
555 static void alloc_gcse_mem
PARAMS ((rtx
));
556 static void free_gcse_mem
PARAMS ((void));
557 static void alloc_reg_set_mem
PARAMS ((int));
558 static void free_reg_set_mem
PARAMS ((void));
559 static int get_bitmap_width
PARAMS ((int, int, int));
560 static void record_one_set
PARAMS ((int, rtx
));
561 static void record_set_info
PARAMS ((rtx
, rtx
, void *));
562 static void compute_sets
PARAMS ((rtx
));
563 static void hash_scan_insn
PARAMS ((rtx
, struct hash_table
*, int));
564 static void hash_scan_set
PARAMS ((rtx
, rtx
, struct hash_table
*));
565 static void hash_scan_clobber
PARAMS ((rtx
, rtx
, struct hash_table
*));
566 static void hash_scan_call
PARAMS ((rtx
, rtx
, struct hash_table
*));
567 static int want_to_gcse_p
PARAMS ((rtx
));
568 static bool gcse_constant_p
PARAMS ((rtx
));
569 static int oprs_unchanged_p
PARAMS ((rtx
, rtx
, int));
570 static int oprs_anticipatable_p
PARAMS ((rtx
, rtx
));
571 static int oprs_available_p
PARAMS ((rtx
, rtx
));
572 static void insert_expr_in_table
PARAMS ((rtx
, enum machine_mode
, rtx
,
573 int, int, struct hash_table
*));
574 static void insert_set_in_table
PARAMS ((rtx
, rtx
, struct hash_table
*));
575 static unsigned int hash_expr
PARAMS ((rtx
, enum machine_mode
, int *, int));
576 static unsigned int hash_expr_1
PARAMS ((rtx
, enum machine_mode
, int *));
577 static unsigned int hash_string_1
PARAMS ((const char *));
578 static unsigned int hash_set
PARAMS ((int, int));
579 static int expr_equiv_p
PARAMS ((rtx
, rtx
));
580 static void record_last_reg_set_info
PARAMS ((rtx
, int));
581 static void record_last_mem_set_info
PARAMS ((rtx
));
582 static void record_last_set_info
PARAMS ((rtx
, rtx
, void *));
583 static void compute_hash_table
PARAMS ((struct hash_table
*));
584 static void alloc_hash_table
PARAMS ((int, struct hash_table
*, int));
585 static void free_hash_table
PARAMS ((struct hash_table
*));
586 static void compute_hash_table_work
PARAMS ((struct hash_table
*));
587 static void dump_hash_table
PARAMS ((FILE *, const char *,
588 struct hash_table
*));
589 static struct expr
*lookup_expr
PARAMS ((rtx
, struct hash_table
*));
590 static struct expr
*lookup_set
PARAMS ((unsigned int, struct hash_table
*));
591 static struct expr
*next_set
PARAMS ((unsigned int, struct expr
*));
592 static void reset_opr_set_tables
PARAMS ((void));
593 static int oprs_not_set_p
PARAMS ((rtx
, rtx
));
594 static void mark_call
PARAMS ((rtx
));
595 static void mark_set
PARAMS ((rtx
, rtx
));
596 static void mark_clobber
PARAMS ((rtx
, rtx
));
597 static void mark_oprs_set
PARAMS ((rtx
));
598 static void alloc_cprop_mem
PARAMS ((int, int));
599 static void free_cprop_mem
PARAMS ((void));
600 static void compute_transp
PARAMS ((rtx
, int, sbitmap
*, int));
601 static void compute_transpout
PARAMS ((void));
602 static void compute_local_properties
PARAMS ((sbitmap
*, sbitmap
*, sbitmap
*,
603 struct hash_table
*));
604 static void compute_cprop_data
PARAMS ((void));
605 static void find_used_regs
PARAMS ((rtx
*, void *));
606 static int try_replace_reg
PARAMS ((rtx
, rtx
, rtx
));
607 static struct expr
*find_avail_set
PARAMS ((int, rtx
));
608 static int cprop_jump
PARAMS ((basic_block
, rtx
, rtx
, rtx
, rtx
));
609 static void mems_conflict_for_gcse_p
PARAMS ((rtx
, rtx
, void *));
610 static int load_killed_in_block_p
PARAMS ((basic_block
, int, rtx
, int));
611 static void canon_list_insert
PARAMS ((rtx
, rtx
, void *));
612 static int cprop_insn
PARAMS ((rtx
, int));
613 static int cprop
PARAMS ((int));
614 static void find_implicit_sets
PARAMS ((void));
615 static int one_cprop_pass
PARAMS ((int, int, int));
616 static bool constprop_register
PARAMS ((rtx
, rtx
, rtx
, int));
617 static struct expr
*find_bypass_set
PARAMS ((int, int));
618 static bool reg_killed_on_edge
PARAMS ((rtx
, edge
));
619 static int bypass_block
PARAMS ((basic_block
, rtx
, rtx
));
620 static int bypass_conditional_jumps
PARAMS ((void));
621 static void alloc_pre_mem
PARAMS ((int, int));
622 static void free_pre_mem
PARAMS ((void));
623 static void compute_pre_data
PARAMS ((void));
624 static int pre_expr_reaches_here_p
PARAMS ((basic_block
, struct expr
*,
626 static void insert_insn_end_bb
PARAMS ((struct expr
*, basic_block
, int));
627 static void pre_insert_copy_insn
PARAMS ((struct expr
*, rtx
));
628 static void pre_insert_copies
PARAMS ((void));
629 static int pre_delete
PARAMS ((void));
630 static int pre_gcse
PARAMS ((void));
631 static int one_pre_gcse_pass
PARAMS ((int));
632 static void add_label_notes
PARAMS ((rtx
, rtx
));
633 static void alloc_code_hoist_mem
PARAMS ((int, int));
634 static void free_code_hoist_mem
PARAMS ((void));
635 static void compute_code_hoist_vbeinout
PARAMS ((void));
636 static void compute_code_hoist_data
PARAMS ((void));
637 static int hoist_expr_reaches_here_p
PARAMS ((basic_block
, int, basic_block
,
639 static void hoist_code
PARAMS ((void));
640 static int one_code_hoisting_pass
PARAMS ((void));
641 static void alloc_rd_mem
PARAMS ((int, int));
642 static void free_rd_mem
PARAMS ((void));
643 static void handle_rd_kill_set
PARAMS ((rtx
, int, basic_block
));
644 static void compute_kill_rd
PARAMS ((void));
645 static void compute_rd
PARAMS ((void));
646 static void alloc_avail_expr_mem
PARAMS ((int, int));
647 static void free_avail_expr_mem
PARAMS ((void));
648 static void compute_ae_gen
PARAMS ((struct hash_table
*));
649 static int expr_killed_p
PARAMS ((rtx
, basic_block
));
650 static void compute_ae_kill
PARAMS ((sbitmap
*, sbitmap
*, struct hash_table
*));
651 static int expr_reaches_here_p
PARAMS ((struct occr
*, struct expr
*,
653 static rtx computing_insn
PARAMS ((struct expr
*, rtx
));
654 static int def_reaches_here_p
PARAMS ((rtx
, rtx
));
655 static int can_disregard_other_sets
PARAMS ((struct reg_set
**, rtx
, int));
656 static int handle_avail_expr
PARAMS ((rtx
, struct expr
*));
657 static int classic_gcse
PARAMS ((void));
658 static int one_classic_gcse_pass
PARAMS ((int));
659 static void invalidate_nonnull_info
PARAMS ((rtx
, rtx
, void *));
660 static int delete_null_pointer_checks_1
PARAMS ((unsigned int *,
661 sbitmap
*, sbitmap
*,
662 struct null_pointer_info
*));
663 static rtx process_insert_insn
PARAMS ((struct expr
*));
664 static int pre_edge_insert
PARAMS ((struct edge_list
*, struct expr
**));
665 static int expr_reaches_here_p_work
PARAMS ((struct occr
*, struct expr
*,
666 basic_block
, int, char *));
667 static int pre_expr_reaches_here_p_work
PARAMS ((basic_block
, struct expr
*,
668 basic_block
, char *));
669 static struct ls_expr
* ldst_entry
PARAMS ((rtx
));
670 static void free_ldst_entry
PARAMS ((struct ls_expr
*));
671 static void free_ldst_mems
PARAMS ((void));
672 static void print_ldst_list
PARAMS ((FILE *));
673 static struct ls_expr
* find_rtx_in_ldst
PARAMS ((rtx
));
674 static int enumerate_ldsts
PARAMS ((void));
675 static inline struct ls_expr
* first_ls_expr
PARAMS ((void));
676 static inline struct ls_expr
* next_ls_expr
PARAMS ((struct ls_expr
*));
677 static int simple_mem
PARAMS ((rtx
));
678 static void invalidate_any_buried_refs
PARAMS ((rtx
));
679 static void compute_ld_motion_mems
PARAMS ((void));
680 static void trim_ld_motion_mems
PARAMS ((void));
681 static void update_ld_motion_stores
PARAMS ((struct expr
*));
682 static void reg_set_info
PARAMS ((rtx
, rtx
, void *));
683 static bool store_ops_ok
PARAMS ((rtx
, int *));
684 static rtx extract_mentioned_regs
PARAMS ((rtx
));
685 static rtx extract_mentioned_regs_helper
PARAMS ((rtx
, rtx
));
686 static void find_moveable_store
PARAMS ((rtx
, int *, int *));
687 static int compute_store_table
PARAMS ((void));
688 static bool load_kills_store
PARAMS ((rtx
, rtx
));
689 static bool find_loads
PARAMS ((rtx
, rtx
));
690 static bool store_killed_in_insn
PARAMS ((rtx
, rtx
, rtx
));
691 static bool store_killed_after
PARAMS ((rtx
, rtx
, rtx
, basic_block
,
693 static bool store_killed_before
PARAMS ((rtx
, rtx
, rtx
, basic_block
,
695 static void build_store_vectors
PARAMS ((void));
696 static void insert_insn_start_bb
PARAMS ((rtx
, basic_block
));
697 static int insert_store
PARAMS ((struct ls_expr
*, edge
));
698 static void replace_store_insn
PARAMS ((rtx
, rtx
, basic_block
));
699 static void delete_store
PARAMS ((struct ls_expr
*,
701 static void free_store_memory
PARAMS ((void));
702 static void store_motion
PARAMS ((void));
703 static void free_insn_expr_list_list
PARAMS ((rtx
*));
704 static void clear_modify_mem_tables
PARAMS ((void));
705 static void free_modify_mem_tables
PARAMS ((void));
706 static rtx gcse_emit_move_after
PARAMS ((rtx
, rtx
, rtx
));
707 static void local_cprop_find_used_regs
PARAMS ((rtx
*, void *));
708 static bool do_local_cprop
PARAMS ((rtx
, rtx
, int, rtx
*));
709 static bool adjust_libcall_notes
PARAMS ((rtx
, rtx
, rtx
, rtx
*));
710 static void local_cprop_pass
PARAMS ((int));
712 /* Entry point for global common subexpression elimination.
713 F is the first instruction in the function. */
721 /* Bytes used at start of pass. */
722 int initial_bytes_used
;
723 /* Maximum number of bytes used by a pass. */
725 /* Point to release obstack data from for each pass. */
726 char *gcse_obstack_bottom
;
728 /* We do not construct an accurate cfg in functions which call
729 setjmp, so just punt to be safe. */
730 if (current_function_calls_setjmp
)
733 /* Assume that we do not need to run jump optimizations after gcse. */
734 run_jump_opt_after_gcse
= 0;
736 /* For calling dump_foo fns from gdb. */
737 debug_stderr
= stderr
;
740 /* Identify the basic block information for this function, including
741 successors and predecessors. */
742 max_gcse_regno
= max_reg_num ();
745 dump_flow_info (file
);
747 /* Return if there's nothing to do. */
748 if (n_basic_blocks
<= 1)
751 /* Trying to perform global optimizations on flow graphs which have
752 a high connectivity will take a long time and is unlikely to be
755 In normal circumstances a cfg should have about twice as many edges
756 as blocks. But we do not want to punish small functions which have
757 a couple switch statements. So we require a relatively large number
758 of basic blocks and the ratio of edges to blocks to be high. */
759 if (n_basic_blocks
> 1000 && n_edges
/ n_basic_blocks
>= 20)
761 if (warn_disabled_optimization
)
762 warning ("GCSE disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
763 n_basic_blocks
, n_edges
/ n_basic_blocks
);
767 /* If allocating memory for the cprop bitmap would take up too much
768 storage it's better just to disable the optimization. */
770 * SBITMAP_SET_SIZE (max_gcse_regno
)
771 * sizeof (SBITMAP_ELT_TYPE
)) > MAX_GCSE_MEMORY
)
773 if (warn_disabled_optimization
)
774 warning ("GCSE disabled: %d basic blocks and %d registers",
775 n_basic_blocks
, max_gcse_regno
);
780 gcc_obstack_init (&gcse_obstack
);
784 init_alias_analysis ();
785 /* Record where pseudo-registers are set. This data is kept accurate
786 during each pass. ??? We could also record hard-reg information here
787 [since it's unchanging], however it is currently done during hash table
790 It may be tempting to compute MEM set information here too, but MEM sets
791 will be subject to code motion one day and thus we need to compute
792 information about memory sets when we build the hash tables. */
794 alloc_reg_set_mem (max_gcse_regno
);
798 initial_bytes_used
= bytes_used
;
800 gcse_obstack_bottom
= gcse_alloc (1);
802 while (changed
&& pass
< MAX_GCSE_PASSES
)
806 fprintf (file
, "GCSE pass %d\n\n", pass
+ 1);
808 /* Initialize bytes_used to the space for the pred/succ lists,
809 and the reg_set_table data. */
810 bytes_used
= initial_bytes_used
;
812 /* Each pass may create new registers, so recalculate each time. */
813 max_gcse_regno
= max_reg_num ();
817 /* Don't allow constant propagation to modify jumps
819 changed
= one_cprop_pass (pass
+ 1, 0, 0);
822 changed
|= one_classic_gcse_pass (pass
+ 1);
825 changed
|= one_pre_gcse_pass (pass
+ 1);
826 /* We may have just created new basic blocks. Release and
827 recompute various things which are sized on the number of
831 free_modify_mem_tables ();
833 = (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
834 canon_modify_mem_list
835 = (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
836 memset ((char *) modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
837 memset ((char *) canon_modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
840 alloc_reg_set_mem (max_reg_num ());
842 run_jump_opt_after_gcse
= 1;
845 if (max_pass_bytes
< bytes_used
)
846 max_pass_bytes
= bytes_used
;
848 /* Free up memory, then reallocate for code hoisting. We can
849 not re-use the existing allocated memory because the tables
850 will not have info for the insns or registers created by
851 partial redundancy elimination. */
854 /* It does not make sense to run code hoisting unless we optimizing
855 for code size -- it rarely makes programs faster, and can make
856 them bigger if we did partial redundancy elimination (when optimizing
857 for space, we use a classic gcse algorithm instead of partial
858 redundancy algorithms). */
861 max_gcse_regno
= max_reg_num ();
863 changed
|= one_code_hoisting_pass ();
866 if (max_pass_bytes
< bytes_used
)
867 max_pass_bytes
= bytes_used
;
872 fprintf (file
, "\n");
876 obstack_free (&gcse_obstack
, gcse_obstack_bottom
);
880 /* Do one last pass of copy propagation, including cprop into
881 conditional jumps. */
883 max_gcse_regno
= max_reg_num ();
885 /* This time, go ahead and allow cprop to alter jumps. */
886 one_cprop_pass (pass
+ 1, 1, 0);
891 fprintf (file
, "GCSE of %s: %d basic blocks, ",
892 current_function_name
, n_basic_blocks
);
893 fprintf (file
, "%d pass%s, %d bytes\n\n",
894 pass
, pass
> 1 ? "es" : "", max_pass_bytes
);
897 obstack_free (&gcse_obstack
, NULL
);
899 /* We are finished with alias. */
900 end_alias_analysis ();
901 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
903 if (!optimize_size
&& flag_gcse_sm
)
906 /* Record where pseudo-registers are set. */
907 return run_jump_opt_after_gcse
;
910 /* Misc. utilities. */
912 /* Nonzero for each mode that supports (set (reg) (reg)).
913 This is trivially true for integer and floating point values.
914 It may or may not be true for condition codes. */
915 static char can_copy
[(int) NUM_MACHINE_MODES
];
917 /* Compute which modes support reg/reg copy operations. */
923 #ifndef AVOID_CCMODE_COPIES
926 memset (can_copy
, 0, NUM_MACHINE_MODES
);
929 for (i
= 0; i
< NUM_MACHINE_MODES
; i
++)
930 if (GET_MODE_CLASS (i
) == MODE_CC
)
932 #ifdef AVOID_CCMODE_COPIES
935 reg
= gen_rtx_REG ((enum machine_mode
) i
, LAST_VIRTUAL_REGISTER
+ 1);
936 insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, reg
));
937 if (recog (PATTERN (insn
), insn
, NULL
) >= 0)
947 /* Returns whether the mode supports reg/reg copy operations. */
951 enum machine_mode mode
;
953 static bool can_copy_init_p
= false;
955 if (! can_copy_init_p
)
958 can_copy_init_p
= true;
961 return can_copy
[mode
] != 0;
964 /* Cover function to xmalloc to record bytes allocated. */
971 return xmalloc (size
);
974 /* Cover function to xrealloc.
975 We don't record the additional size since we don't know it.
976 It won't affect memory usage stats much anyway. */
983 return xrealloc (ptr
, size
);
986 /* Cover function to obstack_alloc. */
993 return (char *) obstack_alloc (&gcse_obstack
, size
);
996 /* Allocate memory for the cuid mapping array,
997 and reg/memory set tracking tables.
999 This is called at the start of each pass. */
1008 /* Find the largest UID and create a mapping from UIDs to CUIDs.
1009 CUIDs are like UIDs except they increase monotonically, have no gaps,
1010 and only apply to real insns. */
1012 max_uid
= get_max_uid ();
1013 n
= (max_uid
+ 1) * sizeof (int);
1014 uid_cuid
= (int *) gmalloc (n
);
1015 memset ((char *) uid_cuid
, 0, n
);
1016 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
1019 uid_cuid
[INSN_UID (insn
)] = i
++;
1021 uid_cuid
[INSN_UID (insn
)] = i
;
1024 /* Create a table mapping cuids to insns. */
1027 n
= (max_cuid
+ 1) * sizeof (rtx
);
1028 cuid_insn
= (rtx
*) gmalloc (n
);
1029 memset ((char *) cuid_insn
, 0, n
);
1030 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
1032 CUID_INSN (i
++) = insn
;
1034 /* Allocate vars to track sets of regs. */
1035 reg_set_bitmap
= BITMAP_XMALLOC ();
1037 /* Allocate vars to track sets of regs, memory per block. */
1038 reg_set_in_block
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
,
1040 /* Allocate array to keep a list of insns which modify memory in each
1042 modify_mem_list
= (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
1043 canon_modify_mem_list
= (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
1044 memset ((char *) modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
1045 memset ((char *) canon_modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
1046 modify_mem_list_set
= BITMAP_XMALLOC ();
1047 canon_modify_mem_list_set
= BITMAP_XMALLOC ();
1050 /* Free memory allocated by alloc_gcse_mem. */
1058 BITMAP_XFREE (reg_set_bitmap
);
1060 sbitmap_vector_free (reg_set_in_block
);
1061 free_modify_mem_tables ();
1062 BITMAP_XFREE (modify_mem_list_set
);
1063 BITMAP_XFREE (canon_modify_mem_list_set
);
1066 /* Many of the global optimization algorithms work by solving dataflow
1067 equations for various expressions. Initially, some local value is
1068 computed for each expression in each block. Then, the values across the
1069 various blocks are combined (by following flow graph edges) to arrive at
1070 global values. Conceptually, each set of equations is independent. We
1071 may therefore solve all the equations in parallel, solve them one at a
1072 time, or pick any intermediate approach.
1074 When you're going to need N two-dimensional bitmaps, each X (say, the
1075 number of blocks) by Y (say, the number of expressions), call this
1076 function. It's not important what X and Y represent; only that Y
1077 correspond to the things that can be done in parallel. This function will
1078 return an appropriate chunking factor C; you should solve C sets of
1079 equations in parallel. By going through this function, we can easily
1080 trade space against time; by solving fewer equations in parallel we use
1084 get_bitmap_width (n
, x
, y
)
1089 /* It's not really worth figuring out *exactly* how much memory will
1090 be used by a particular choice. The important thing is to get
1091 something approximately right. */
1092 size_t max_bitmap_memory
= 10 * 1024 * 1024;
1094 /* The number of bytes we'd use for a single column of minimum
1096 size_t column_size
= n
* x
* sizeof (SBITMAP_ELT_TYPE
);
1098 /* Often, it's reasonable just to solve all the equations in
1100 if (column_size
* SBITMAP_SET_SIZE (y
) <= max_bitmap_memory
)
1103 /* Otherwise, pick the largest width we can, without going over the
1105 return SBITMAP_ELT_BITS
* ((max_bitmap_memory
+ column_size
- 1)
1109 /* Compute the local properties of each recorded expression.
1111 Local properties are those that are defined by the block, irrespective of
1114 An expression is transparent in a block if its operands are not modified
1117 An expression is computed (locally available) in a block if it is computed
1118 at least once and expression would contain the same value if the
1119 computation was moved to the end of the block.
1121 An expression is locally anticipatable in a block if it is computed at
1122 least once and expression would contain the same value if the computation
1123 was moved to the beginning of the block.
1125 We call this routine for cprop, pre and code hoisting. They all compute
1126 basically the same information and thus can easily share this code.
1128 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1129 properties. If NULL, then it is not necessary to compute or record that
1130 particular property.
1132 TABLE controls which hash table to look at. If it is set hash table,
1133 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1137 compute_local_properties (transp
, comp
, antloc
, table
)
1141 struct hash_table
*table
;
1145 /* Initialize any bitmaps that were passed in. */
1149 sbitmap_vector_zero (transp
, last_basic_block
);
1151 sbitmap_vector_ones (transp
, last_basic_block
);
1155 sbitmap_vector_zero (comp
, last_basic_block
);
1157 sbitmap_vector_zero (antloc
, last_basic_block
);
1159 for (i
= 0; i
< table
->size
; i
++)
1163 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1165 int indx
= expr
->bitmap_index
;
1168 /* The expression is transparent in this block if it is not killed.
1169 We start by assuming all are transparent [none are killed], and
1170 then reset the bits for those that are. */
1172 compute_transp (expr
->expr
, indx
, transp
, table
->set_p
);
1174 /* The occurrences recorded in antic_occr are exactly those that
1175 we want to set to nonzero in ANTLOC. */
1177 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
1179 SET_BIT (antloc
[BLOCK_NUM (occr
->insn
)], indx
);
1181 /* While we're scanning the table, this is a good place to
1183 occr
->deleted_p
= 0;
1186 /* The occurrences recorded in avail_occr are exactly those that
1187 we want to set to nonzero in COMP. */
1189 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
1191 SET_BIT (comp
[BLOCK_NUM (occr
->insn
)], indx
);
1193 /* While we're scanning the table, this is a good place to
1198 /* While we're scanning the table, this is a good place to
1200 expr
->reaching_reg
= 0;
1205 /* Register set information.
1207 `reg_set_table' records where each register is set or otherwise
1210 static struct obstack reg_set_obstack
;
1213 alloc_reg_set_mem (n_regs
)
1218 reg_set_table_size
= n_regs
+ REG_SET_TABLE_SLOP
;
1219 n
= reg_set_table_size
* sizeof (struct reg_set
*);
1220 reg_set_table
= (struct reg_set
**) gmalloc (n
);
1221 memset ((char *) reg_set_table
, 0, n
);
1223 gcc_obstack_init (®_set_obstack
);
1229 free (reg_set_table
);
1230 obstack_free (®_set_obstack
, NULL
);
1233 /* Record REGNO in the reg_set table. */
1236 record_one_set (regno
, insn
)
1240 /* Allocate a new reg_set element and link it onto the list. */
1241 struct reg_set
*new_reg_info
;
1243 /* If the table isn't big enough, enlarge it. */
1244 if (regno
>= reg_set_table_size
)
1246 int new_size
= regno
+ REG_SET_TABLE_SLOP
;
1249 = (struct reg_set
**) grealloc ((char *) reg_set_table
,
1250 new_size
* sizeof (struct reg_set
*));
1251 memset ((char *) (reg_set_table
+ reg_set_table_size
), 0,
1252 (new_size
- reg_set_table_size
) * sizeof (struct reg_set
*));
1253 reg_set_table_size
= new_size
;
1256 new_reg_info
= (struct reg_set
*) obstack_alloc (®_set_obstack
,
1257 sizeof (struct reg_set
));
1258 bytes_used
+= sizeof (struct reg_set
);
1259 new_reg_info
->insn
= insn
;
1260 new_reg_info
->next
= reg_set_table
[regno
];
1261 reg_set_table
[regno
] = new_reg_info
;
1264 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1265 an insn. The DATA is really the instruction in which the SET is
1269 record_set_info (dest
, setter
, data
)
1270 rtx dest
, setter ATTRIBUTE_UNUSED
;
1273 rtx record_set_insn
= (rtx
) data
;
1275 if (GET_CODE (dest
) == REG
&& REGNO (dest
) >= FIRST_PSEUDO_REGISTER
)
1276 record_one_set (REGNO (dest
), record_set_insn
);
1279 /* Scan the function and record each set of each pseudo-register.
1281 This is called once, at the start of the gcse pass. See the comments for
1282 `reg_set_table' for further documentation. */
1290 for (insn
= f
; insn
!= 0; insn
= NEXT_INSN (insn
))
1292 note_stores (PATTERN (insn
), record_set_info
, insn
);
1295 /* Hash table support. */
1297 struct reg_avail_info
1299 basic_block last_bb
;
1304 static struct reg_avail_info
*reg_avail_info
;
1305 static basic_block current_bb
;
1308 /* See whether X, the source of a set, is something we want to consider for
1311 static GTY(()) rtx test_insn
;
1316 int num_clobbers
= 0;
1319 switch (GET_CODE (x
))
1327 case CONSTANT_P_RTX
:
1334 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1335 if (general_operand (x
, GET_MODE (x
)))
1337 else if (GET_MODE (x
) == VOIDmode
)
1340 /* Otherwise, check if we can make a valid insn from it. First initialize
1341 our test insn if we haven't already. */
1345 = make_insn_raw (gen_rtx_SET (VOIDmode
,
1346 gen_rtx_REG (word_mode
,
1347 FIRST_PSEUDO_REGISTER
* 2),
1349 NEXT_INSN (test_insn
) = PREV_INSN (test_insn
) = 0;
1352 /* Now make an insn like the one we would make when GCSE'ing and see if
1354 PUT_MODE (SET_DEST (PATTERN (test_insn
)), GET_MODE (x
));
1355 SET_SRC (PATTERN (test_insn
)) = x
;
1356 return ((icode
= recog (PATTERN (test_insn
), test_insn
, &num_clobbers
)) >= 0
1357 && (num_clobbers
== 0 || ! added_clobbers_hard_reg_p (icode
)));
1360 /* Return nonzero if the operands of expression X are unchanged from the
1361 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1362 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1365 oprs_unchanged_p (x
, insn
, avail_p
)
1376 code
= GET_CODE (x
);
1381 struct reg_avail_info
*info
= ®_avail_info
[REGNO (x
)];
1383 if (info
->last_bb
!= current_bb
)
1386 return info
->last_set
< INSN_CUID (insn
);
1388 return info
->first_set
>= INSN_CUID (insn
);
1392 if (load_killed_in_block_p (current_bb
, INSN_CUID (insn
),
1396 return oprs_unchanged_p (XEXP (x
, 0), insn
, avail_p
);
1422 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1426 /* If we are about to do the last recursive call needed at this
1427 level, change it into iteration. This function is called enough
1430 return oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
);
1432 else if (! oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
))
1435 else if (fmt
[i
] == 'E')
1436 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1437 if (! oprs_unchanged_p (XVECEXP (x
, i
, j
), insn
, avail_p
))
1444 /* Used for communication between mems_conflict_for_gcse_p and
1445 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1446 conflict between two memory references. */
1447 static int gcse_mems_conflict_p
;
1449 /* Used for communication between mems_conflict_for_gcse_p and
1450 load_killed_in_block_p. A memory reference for a load instruction,
1451 mems_conflict_for_gcse_p will see if a memory store conflicts with
1452 this memory load. */
1453 static rtx gcse_mem_operand
;
1455 /* DEST is the output of an instruction. If it is a memory reference, and
1456 possibly conflicts with the load found in gcse_mem_operand, then set
1457 gcse_mems_conflict_p to a nonzero value. */
1460 mems_conflict_for_gcse_p (dest
, setter
, data
)
1461 rtx dest
, setter ATTRIBUTE_UNUSED
;
1462 void *data ATTRIBUTE_UNUSED
;
1464 while (GET_CODE (dest
) == SUBREG
1465 || GET_CODE (dest
) == ZERO_EXTRACT
1466 || GET_CODE (dest
) == SIGN_EXTRACT
1467 || GET_CODE (dest
) == STRICT_LOW_PART
)
1468 dest
= XEXP (dest
, 0);
1470 /* If DEST is not a MEM, then it will not conflict with the load. Note
1471 that function calls are assumed to clobber memory, but are handled
1473 if (GET_CODE (dest
) != MEM
)
1476 /* If we are setting a MEM in our list of specially recognized MEMs,
1477 don't mark as killed this time. */
1479 if (expr_equiv_p (dest
, gcse_mem_operand
) && pre_ldst_mems
!= NULL
)
1481 if (!find_rtx_in_ldst (dest
))
1482 gcse_mems_conflict_p
= 1;
1486 if (true_dependence (dest
, GET_MODE (dest
), gcse_mem_operand
,
1488 gcse_mems_conflict_p
= 1;
1491 /* Return nonzero if the expression in X (a memory reference) is killed
1492 in block BB before or after the insn with the CUID in UID_LIMIT.
1493 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1496 To check the entire block, set UID_LIMIT to max_uid + 1 and
1500 load_killed_in_block_p (bb
, uid_limit
, x
, avail_p
)
1506 rtx list_entry
= modify_mem_list
[bb
->index
];
1510 /* Ignore entries in the list that do not apply. */
1512 && INSN_CUID (XEXP (list_entry
, 0)) < uid_limit
)
1514 && INSN_CUID (XEXP (list_entry
, 0)) > uid_limit
))
1516 list_entry
= XEXP (list_entry
, 1);
1520 setter
= XEXP (list_entry
, 0);
1522 /* If SETTER is a call everything is clobbered. Note that calls
1523 to pure functions are never put on the list, so we need not
1524 worry about them. */
1525 if (GET_CODE (setter
) == CALL_INSN
)
1528 /* SETTER must be an INSN of some kind that sets memory. Call
1529 note_stores to examine each hunk of memory that is modified.
1531 The note_stores interface is pretty limited, so we have to
1532 communicate via global variables. Yuk. */
1533 gcse_mem_operand
= x
;
1534 gcse_mems_conflict_p
= 0;
1535 note_stores (PATTERN (setter
), mems_conflict_for_gcse_p
, NULL
);
1536 if (gcse_mems_conflict_p
)
1538 list_entry
= XEXP (list_entry
, 1);
1543 /* Return nonzero if the operands of expression X are unchanged from
1544 the start of INSN's basic block up to but not including INSN. */
1547 oprs_anticipatable_p (x
, insn
)
1550 return oprs_unchanged_p (x
, insn
, 0);
1553 /* Return nonzero if the operands of expression X are unchanged from
1554 INSN to the end of INSN's basic block. */
1557 oprs_available_p (x
, insn
)
1560 return oprs_unchanged_p (x
, insn
, 1);
1563 /* Hash expression X.
1565 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1566 indicating if a volatile operand is found or if the expression contains
1567 something we don't want to insert in the table.
1569 ??? One might want to merge this with canon_hash. Later. */
1572 hash_expr (x
, mode
, do_not_record_p
, hash_table_size
)
1574 enum machine_mode mode
;
1575 int *do_not_record_p
;
1576 int hash_table_size
;
1580 *do_not_record_p
= 0;
1582 hash
= hash_expr_1 (x
, mode
, do_not_record_p
);
1583 return hash
% hash_table_size
;
1586 /* Hash a string. Just add its bytes up. */
1588 static inline unsigned
1593 const unsigned char *p
= (const unsigned char *) ps
;
1602 /* Subroutine of hash_expr to do the actual work. */
1605 hash_expr_1 (x
, mode
, do_not_record_p
)
1607 enum machine_mode mode
;
1608 int *do_not_record_p
;
1615 /* Used to turn recursion into iteration. We can't rely on GCC's
1616 tail-recursion elimination since we need to keep accumulating values
1623 code
= GET_CODE (x
);
1627 hash
+= ((unsigned int) REG
<< 7) + REGNO (x
);
1631 hash
+= (((unsigned int) CONST_INT
<< 7) + (unsigned int) mode
1632 + (unsigned int) INTVAL (x
));
1636 /* This is like the general case, except that it only counts
1637 the integers representing the constant. */
1638 hash
+= (unsigned int) code
+ (unsigned int) GET_MODE (x
);
1639 if (GET_MODE (x
) != VOIDmode
)
1640 for (i
= 2; i
< GET_RTX_LENGTH (CONST_DOUBLE
); i
++)
1641 hash
+= (unsigned int) XWINT (x
, i
);
1643 hash
+= ((unsigned int) CONST_DOUBLE_LOW (x
)
1644 + (unsigned int) CONST_DOUBLE_HIGH (x
));
1652 units
= CONST_VECTOR_NUNITS (x
);
1654 for (i
= 0; i
< units
; ++i
)
1656 elt
= CONST_VECTOR_ELT (x
, i
);
1657 hash
+= hash_expr_1 (elt
, GET_MODE (elt
), do_not_record_p
);
1663 /* Assume there is only one rtx object for any given label. */
1665 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1666 differences and differences between each stage's debugging dumps. */
1667 hash
+= (((unsigned int) LABEL_REF
<< 7)
1668 + CODE_LABEL_NUMBER (XEXP (x
, 0)));
1673 /* Don't hash on the symbol's address to avoid bootstrap differences.
1674 Different hash values may cause expressions to be recorded in
1675 different orders and thus different registers to be used in the
1676 final assembler. This also avoids differences in the dump files
1677 between various stages. */
1679 const unsigned char *p
= (const unsigned char *) XSTR (x
, 0);
1682 h
+= (h
<< 7) + *p
++; /* ??? revisit */
1684 hash
+= ((unsigned int) SYMBOL_REF
<< 7) + h
;
1689 if (MEM_VOLATILE_P (x
))
1691 *do_not_record_p
= 1;
1695 hash
+= (unsigned int) MEM
;
1696 /* We used alias set for hashing, but this is not good, since the alias
1697 set may differ in -fprofile-arcs and -fbranch-probabilities compilation
1698 causing the profiles to fail to match. */
1709 case UNSPEC_VOLATILE
:
1710 *do_not_record_p
= 1;
1714 if (MEM_VOLATILE_P (x
))
1716 *do_not_record_p
= 1;
1721 /* We don't want to take the filename and line into account. */
1722 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
)
1723 + hash_string_1 (ASM_OPERANDS_TEMPLATE (x
))
1724 + hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
))
1725 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x
);
1727 if (ASM_OPERANDS_INPUT_LENGTH (x
))
1729 for (i
= 1; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
1731 hash
+= (hash_expr_1 (ASM_OPERANDS_INPUT (x
, i
),
1732 GET_MODE (ASM_OPERANDS_INPUT (x
, i
)),
1734 + hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT
1738 hash
+= hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x
, 0));
1739 x
= ASM_OPERANDS_INPUT (x
, 0);
1740 mode
= GET_MODE (x
);
1750 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
);
1751 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1755 /* If we are about to do the last recursive call
1756 needed at this level, change it into iteration.
1757 This function is called enough to be worth it. */
1764 hash
+= hash_expr_1 (XEXP (x
, i
), 0, do_not_record_p
);
1765 if (*do_not_record_p
)
1769 else if (fmt
[i
] == 'E')
1770 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1772 hash
+= hash_expr_1 (XVECEXP (x
, i
, j
), 0, do_not_record_p
);
1773 if (*do_not_record_p
)
1777 else if (fmt
[i
] == 's')
1778 hash
+= hash_string_1 (XSTR (x
, i
));
1779 else if (fmt
[i
] == 'i')
1780 hash
+= (unsigned int) XINT (x
, i
);
1788 /* Hash a set of register REGNO.
1790 Sets are hashed on the register that is set. This simplifies the PRE copy
1793 ??? May need to make things more elaborate. Later, as necessary. */
1796 hash_set (regno
, hash_table_size
)
1798 int hash_table_size
;
1803 return hash
% hash_table_size
;
1806 /* Return nonzero if exp1 is equivalent to exp2.
1807 ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
1820 if (x
== 0 || y
== 0)
1823 code
= GET_CODE (x
);
1824 if (code
!= GET_CODE (y
))
1827 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
1828 if (GET_MODE (x
) != GET_MODE (y
))
1839 return XEXP (x
, 0) == XEXP (y
, 0);
1842 return XSTR (x
, 0) == XSTR (y
, 0);
1845 return REGNO (x
) == REGNO (y
);
1848 /* Can't merge two expressions in different alias sets, since we can
1849 decide that the expression is transparent in a block when it isn't,
1850 due to it being set with the different alias set. */
1851 if (MEM_ALIAS_SET (x
) != MEM_ALIAS_SET (y
))
1855 /* For commutative operations, check both orders. */
1863 return ((expr_equiv_p (XEXP (x
, 0), XEXP (y
, 0))
1864 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 1)))
1865 || (expr_equiv_p (XEXP (x
, 0), XEXP (y
, 1))
1866 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 0))));
1869 /* We don't use the generic code below because we want to
1870 disregard filename and line numbers. */
1872 /* A volatile asm isn't equivalent to any other. */
1873 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
1876 if (GET_MODE (x
) != GET_MODE (y
)
1877 || strcmp (ASM_OPERANDS_TEMPLATE (x
), ASM_OPERANDS_TEMPLATE (y
))
1878 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
),
1879 ASM_OPERANDS_OUTPUT_CONSTRAINT (y
))
1880 || ASM_OPERANDS_OUTPUT_IDX (x
) != ASM_OPERANDS_OUTPUT_IDX (y
)
1881 || ASM_OPERANDS_INPUT_LENGTH (x
) != ASM_OPERANDS_INPUT_LENGTH (y
))
1884 if (ASM_OPERANDS_INPUT_LENGTH (x
))
1886 for (i
= ASM_OPERANDS_INPUT_LENGTH (x
) - 1; i
>= 0; i
--)
1887 if (! expr_equiv_p (ASM_OPERANDS_INPUT (x
, i
),
1888 ASM_OPERANDS_INPUT (y
, i
))
1889 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x
, i
),
1890 ASM_OPERANDS_INPUT_CONSTRAINT (y
, i
)))
1900 /* Compare the elements. If any pair of corresponding elements
1901 fail to match, return 0 for the whole thing. */
1903 fmt
= GET_RTX_FORMAT (code
);
1904 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1909 if (! expr_equiv_p (XEXP (x
, i
), XEXP (y
, i
)))
1914 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1916 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1917 if (! expr_equiv_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
1922 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1927 if (XINT (x
, i
) != XINT (y
, i
))
1932 if (XWINT (x
, i
) != XWINT (y
, i
))
1947 /* Insert expression X in INSN in the hash TABLE.
1948 If it is already present, record it as the last occurrence in INSN's
1951 MODE is the mode of the value X is being stored into.
1952 It is only used if X is a CONST_INT.
1954 ANTIC_P is nonzero if X is an anticipatable expression.
1955 AVAIL_P is nonzero if X is an available expression. */
1958 insert_expr_in_table (x
, mode
, insn
, antic_p
, avail_p
, table
)
1960 enum machine_mode mode
;
1962 int antic_p
, avail_p
;
1963 struct hash_table
*table
;
1965 int found
, do_not_record_p
;
1967 struct expr
*cur_expr
, *last_expr
= NULL
;
1968 struct occr
*antic_occr
, *avail_occr
;
1969 struct occr
*last_occr
= NULL
;
1971 hash
= hash_expr (x
, mode
, &do_not_record_p
, table
->size
);
1973 /* Do not insert expression in table if it contains volatile operands,
1974 or if hash_expr determines the expression is something we don't want
1975 to or can't handle. */
1976 if (do_not_record_p
)
1979 cur_expr
= table
->table
[hash
];
1982 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1984 /* If the expression isn't found, save a pointer to the end of
1986 last_expr
= cur_expr
;
1987 cur_expr
= cur_expr
->next_same_hash
;
1992 cur_expr
= (struct expr
*) gcse_alloc (sizeof (struct expr
));
1993 bytes_used
+= sizeof (struct expr
);
1994 if (table
->table
[hash
] == NULL
)
1995 /* This is the first pattern that hashed to this index. */
1996 table
->table
[hash
] = cur_expr
;
1998 /* Add EXPR to end of this hash chain. */
1999 last_expr
->next_same_hash
= cur_expr
;
2001 /* Set the fields of the expr element. */
2003 cur_expr
->bitmap_index
= table
->n_elems
++;
2004 cur_expr
->next_same_hash
= NULL
;
2005 cur_expr
->antic_occr
= NULL
;
2006 cur_expr
->avail_occr
= NULL
;
2009 /* Now record the occurrence(s). */
2012 antic_occr
= cur_expr
->antic_occr
;
2014 /* Search for another occurrence in the same basic block. */
2015 while (antic_occr
&& BLOCK_NUM (antic_occr
->insn
) != BLOCK_NUM (insn
))
2017 /* If an occurrence isn't found, save a pointer to the end of
2019 last_occr
= antic_occr
;
2020 antic_occr
= antic_occr
->next
;
2024 /* Found another instance of the expression in the same basic block.
2025 Prefer the currently recorded one. We want the first one in the
2026 block and the block is scanned from start to end. */
2027 ; /* nothing to do */
2030 /* First occurrence of this expression in this basic block. */
2031 antic_occr
= (struct occr
*) gcse_alloc (sizeof (struct occr
));
2032 bytes_used
+= sizeof (struct occr
);
2033 /* First occurrence of this expression in any block? */
2034 if (cur_expr
->antic_occr
== NULL
)
2035 cur_expr
->antic_occr
= antic_occr
;
2037 last_occr
->next
= antic_occr
;
2039 antic_occr
->insn
= insn
;
2040 antic_occr
->next
= NULL
;
2046 avail_occr
= cur_expr
->avail_occr
;
2048 /* Search for another occurrence in the same basic block. */
2049 while (avail_occr
&& BLOCK_NUM (avail_occr
->insn
) != BLOCK_NUM (insn
))
2051 /* If an occurrence isn't found, save a pointer to the end of
2053 last_occr
= avail_occr
;
2054 avail_occr
= avail_occr
->next
;
2058 /* Found another instance of the expression in the same basic block.
2059 Prefer this occurrence to the currently recorded one. We want
2060 the last one in the block and the block is scanned from start
2062 avail_occr
->insn
= insn
;
2065 /* First occurrence of this expression in this basic block. */
2066 avail_occr
= (struct occr
*) gcse_alloc (sizeof (struct occr
));
2067 bytes_used
+= sizeof (struct occr
);
2069 /* First occurrence of this expression in any block? */
2070 if (cur_expr
->avail_occr
== NULL
)
2071 cur_expr
->avail_occr
= avail_occr
;
2073 last_occr
->next
= avail_occr
;
2075 avail_occr
->insn
= insn
;
2076 avail_occr
->next
= NULL
;
2081 /* Insert pattern X in INSN in the hash table.
2082 X is a SET of a reg to either another reg or a constant.
2083 If it is already present, record it as the last occurrence in INSN's
2087 insert_set_in_table (x
, insn
, table
)
2090 struct hash_table
*table
;
2094 struct expr
*cur_expr
, *last_expr
= NULL
;
2095 struct occr
*cur_occr
, *last_occr
= NULL
;
2097 if (GET_CODE (x
) != SET
2098 || GET_CODE (SET_DEST (x
)) != REG
)
2101 hash
= hash_set (REGNO (SET_DEST (x
)), table
->size
);
2103 cur_expr
= table
->table
[hash
];
2106 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
2108 /* If the expression isn't found, save a pointer to the end of
2110 last_expr
= cur_expr
;
2111 cur_expr
= cur_expr
->next_same_hash
;
2116 cur_expr
= (struct expr
*) gcse_alloc (sizeof (struct expr
));
2117 bytes_used
+= sizeof (struct expr
);
2118 if (table
->table
[hash
] == NULL
)
2119 /* This is the first pattern that hashed to this index. */
2120 table
->table
[hash
] = cur_expr
;
2122 /* Add EXPR to end of this hash chain. */
2123 last_expr
->next_same_hash
= cur_expr
;
2125 /* Set the fields of the expr element.
2126 We must copy X because it can be modified when copy propagation is
2127 performed on its operands. */
2128 cur_expr
->expr
= copy_rtx (x
);
2129 cur_expr
->bitmap_index
= table
->n_elems
++;
2130 cur_expr
->next_same_hash
= NULL
;
2131 cur_expr
->antic_occr
= NULL
;
2132 cur_expr
->avail_occr
= NULL
;
2135 /* Now record the occurrence. */
2136 cur_occr
= cur_expr
->avail_occr
;
2138 /* Search for another occurrence in the same basic block. */
2139 while (cur_occr
&& BLOCK_NUM (cur_occr
->insn
) != BLOCK_NUM (insn
))
2141 /* If an occurrence isn't found, save a pointer to the end of
2143 last_occr
= cur_occr
;
2144 cur_occr
= cur_occr
->next
;
2148 /* Found another instance of the expression in the same basic block.
2149 Prefer this occurrence to the currently recorded one. We want the
2150 last one in the block and the block is scanned from start to end. */
2151 cur_occr
->insn
= insn
;
2154 /* First occurrence of this expression in this basic block. */
2155 cur_occr
= (struct occr
*) gcse_alloc (sizeof (struct occr
));
2156 bytes_used
+= sizeof (struct occr
);
2158 /* First occurrence of this expression in any block? */
2159 if (cur_expr
->avail_occr
== NULL
)
2160 cur_expr
->avail_occr
= cur_occr
;
2162 last_occr
->next
= cur_occr
;
2164 cur_occr
->insn
= insn
;
2165 cur_occr
->next
= NULL
;
2169 /* Determine whether the rtx X should be treated as a constant for
2170 the purposes of GCSE's constant propagation. */
2176 /* Consider a COMPARE of two integers constant. */
2177 if (GET_CODE (x
) == COMPARE
2178 && GET_CODE (XEXP (x
, 0)) == CONST_INT
2179 && GET_CODE (XEXP (x
, 1)) == CONST_INT
)
2182 if (GET_CODE (x
) == CONSTANT_P_RTX
)
2185 return CONSTANT_P (x
);
2188 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
2192 hash_scan_set (pat
, insn
, table
)
2194 struct hash_table
*table
;
2196 rtx src
= SET_SRC (pat
);
2197 rtx dest
= SET_DEST (pat
);
2200 if (GET_CODE (src
) == CALL
)
2201 hash_scan_call (src
, insn
, table
);
2203 else if (GET_CODE (dest
) == REG
)
2205 unsigned int regno
= REGNO (dest
);
2208 /* If this is a single set and we are doing constant propagation,
2209 see if a REG_NOTE shows this equivalent to a constant. */
2210 if (table
->set_p
&& (note
= find_reg_equal_equiv_note (insn
)) != 0
2211 && gcse_constant_p (XEXP (note
, 0)))
2212 src
= XEXP (note
, 0), pat
= gen_rtx_SET (VOIDmode
, dest
, src
);
2214 /* Only record sets of pseudo-regs in the hash table. */
2216 && regno
>= FIRST_PSEUDO_REGISTER
2217 /* Don't GCSE something if we can't do a reg/reg copy. */
2218 && can_copy_p (GET_MODE (dest
))
2219 /* GCSE commonly inserts instruction after the insn. We can't
2220 do that easily for EH_REGION notes so disable GCSE on these
2222 && !find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
2223 /* Is SET_SRC something we want to gcse? */
2224 && want_to_gcse_p (src
)
2225 /* Don't CSE a nop. */
2226 && ! set_noop_p (pat
)
2227 /* Don't GCSE if it has attached REG_EQUIV note.
2228 At this point this only function parameters should have
2229 REG_EQUIV notes and if the argument slot is used somewhere
2230 explicitly, it means address of parameter has been taken,
2231 so we should not extend the lifetime of the pseudo. */
2232 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
2233 || GET_CODE (XEXP (note
, 0)) != MEM
))
2235 /* An expression is not anticipatable if its operands are
2236 modified before this insn or if this is not the only SET in
2238 int antic_p
= oprs_anticipatable_p (src
, insn
) && single_set (insn
);
2239 /* An expression is not available if its operands are
2240 subsequently modified, including this insn. It's also not
2241 available if this is a branch, because we can't insert
2242 a set after the branch. */
2243 int avail_p
= (oprs_available_p (src
, insn
)
2244 && ! JUMP_P (insn
));
2246 insert_expr_in_table (src
, GET_MODE (dest
), insn
, antic_p
, avail_p
, table
);
2249 /* Record sets for constant/copy propagation. */
2250 else if (table
->set_p
2251 && regno
>= FIRST_PSEUDO_REGISTER
2252 && ((GET_CODE (src
) == REG
2253 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
2254 && can_copy_p (GET_MODE (dest
))
2255 && REGNO (src
) != regno
)
2256 || gcse_constant_p (src
))
2257 /* A copy is not available if its src or dest is subsequently
2258 modified. Here we want to search from INSN+1 on, but
2259 oprs_available_p searches from INSN on. */
2260 && (insn
== BLOCK_END (BLOCK_NUM (insn
))
2261 || ((tmp
= next_nonnote_insn (insn
)) != NULL_RTX
2262 && oprs_available_p (pat
, tmp
))))
2263 insert_set_in_table (pat
, insn
, table
);
2268 hash_scan_clobber (x
, insn
, table
)
2269 rtx x ATTRIBUTE_UNUSED
, insn ATTRIBUTE_UNUSED
;
2270 struct hash_table
*table ATTRIBUTE_UNUSED
;
2272 /* Currently nothing to do. */
2276 hash_scan_call (x
, insn
, table
)
2277 rtx x ATTRIBUTE_UNUSED
, insn ATTRIBUTE_UNUSED
;
2278 struct hash_table
*table ATTRIBUTE_UNUSED
;
2280 /* Currently nothing to do. */
2283 /* Process INSN and add hash table entries as appropriate.
2285 Only available expressions that set a single pseudo-reg are recorded.
2287 Single sets in a PARALLEL could be handled, but it's an extra complication
2288 that isn't dealt with right now. The trick is handling the CLOBBERs that
2289 are also in the PARALLEL. Later.
2291 If SET_P is nonzero, this is for the assignment hash table,
2292 otherwise it is for the expression hash table.
2293 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
2294 not record any expressions. */
2297 hash_scan_insn (insn
, table
, in_libcall_block
)
2299 struct hash_table
*table
;
2300 int in_libcall_block
;
2302 rtx pat
= PATTERN (insn
);
2305 if (in_libcall_block
)
2308 /* Pick out the sets of INSN and for other forms of instructions record
2309 what's been modified. */
2311 if (GET_CODE (pat
) == SET
)
2312 hash_scan_set (pat
, insn
, table
);
2313 else if (GET_CODE (pat
) == PARALLEL
)
2314 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2316 rtx x
= XVECEXP (pat
, 0, i
);
2318 if (GET_CODE (x
) == SET
)
2319 hash_scan_set (x
, insn
, table
);
2320 else if (GET_CODE (x
) == CLOBBER
)
2321 hash_scan_clobber (x
, insn
, table
);
2322 else if (GET_CODE (x
) == CALL
)
2323 hash_scan_call (x
, insn
, table
);
2326 else if (GET_CODE (pat
) == CLOBBER
)
2327 hash_scan_clobber (pat
, insn
, table
);
2328 else if (GET_CODE (pat
) == CALL
)
2329 hash_scan_call (pat
, insn
, table
);
2333 dump_hash_table (file
, name
, table
)
2336 struct hash_table
*table
;
2339 /* Flattened out table, so it's printed in proper order. */
2340 struct expr
**flat_table
;
2341 unsigned int *hash_val
;
2345 = (struct expr
**) xcalloc (table
->n_elems
, sizeof (struct expr
*));
2346 hash_val
= (unsigned int *) xmalloc (table
->n_elems
* sizeof (unsigned int));
2348 for (i
= 0; i
< (int) table
->size
; i
++)
2349 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
2351 flat_table
[expr
->bitmap_index
] = expr
;
2352 hash_val
[expr
->bitmap_index
] = i
;
2355 fprintf (file
, "%s hash table (%d buckets, %d entries)\n",
2356 name
, table
->size
, table
->n_elems
);
2358 for (i
= 0; i
< (int) table
->n_elems
; i
++)
2359 if (flat_table
[i
] != 0)
2361 expr
= flat_table
[i
];
2362 fprintf (file
, "Index %d (hash value %d)\n ",
2363 expr
->bitmap_index
, hash_val
[i
]);
2364 print_rtl (file
, expr
->expr
);
2365 fprintf (file
, "\n");
2368 fprintf (file
, "\n");
2374 /* Record register first/last/block set information for REGNO in INSN.
2376 first_set records the first place in the block where the register
2377 is set and is used to compute "anticipatability".
2379 last_set records the last place in the block where the register
2380 is set and is used to compute "availability".
2382 last_bb records the block for which first_set and last_set are
2383 valid, as a quick test to invalidate them.
2385 reg_set_in_block records whether the register is set in the block
2386 and is used to compute "transparency". */
2389 record_last_reg_set_info (insn
, regno
)
2393 struct reg_avail_info
*info
= ®_avail_info
[regno
];
2394 int cuid
= INSN_CUID (insn
);
2396 info
->last_set
= cuid
;
2397 if (info
->last_bb
!= current_bb
)
2399 info
->last_bb
= current_bb
;
2400 info
->first_set
= cuid
;
2401 SET_BIT (reg_set_in_block
[current_bb
->index
], regno
);
2406 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
2407 Note we store a pair of elements in the list, so they have to be
2408 taken off pairwise. */
2411 canon_list_insert (dest
, unused1
, v_insn
)
2412 rtx dest ATTRIBUTE_UNUSED
;
2413 rtx unused1 ATTRIBUTE_UNUSED
;
2416 rtx dest_addr
, insn
;
2419 while (GET_CODE (dest
) == SUBREG
2420 || GET_CODE (dest
) == ZERO_EXTRACT
2421 || GET_CODE (dest
) == SIGN_EXTRACT
2422 || GET_CODE (dest
) == STRICT_LOW_PART
)
2423 dest
= XEXP (dest
, 0);
2425 /* If DEST is not a MEM, then it will not conflict with a load. Note
2426 that function calls are assumed to clobber memory, but are handled
2429 if (GET_CODE (dest
) != MEM
)
2432 dest_addr
= get_addr (XEXP (dest
, 0));
2433 dest_addr
= canon_rtx (dest_addr
);
2434 insn
= (rtx
) v_insn
;
2435 bb
= BLOCK_NUM (insn
);
2437 canon_modify_mem_list
[bb
] =
2438 alloc_EXPR_LIST (VOIDmode
, dest_addr
, canon_modify_mem_list
[bb
]);
2439 canon_modify_mem_list
[bb
] =
2440 alloc_EXPR_LIST (VOIDmode
, dest
, canon_modify_mem_list
[bb
]);
2441 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2444 /* Record memory modification information for INSN. We do not actually care
2445 about the memory location(s) that are set, or even how they are set (consider
2446 a CALL_INSN). We merely need to record which insns modify memory. */
2449 record_last_mem_set_info (insn
)
2452 int bb
= BLOCK_NUM (insn
);
2454 /* load_killed_in_block_p will handle the case of calls clobbering
2456 modify_mem_list
[bb
] = alloc_INSN_LIST (insn
, modify_mem_list
[bb
]);
2457 bitmap_set_bit (modify_mem_list_set
, bb
);
2459 if (GET_CODE (insn
) == CALL_INSN
)
2461 /* Note that traversals of this loop (other than for free-ing)
2462 will break after encountering a CALL_INSN. So, there's no
2463 need to insert a pair of items, as canon_list_insert does. */
2464 canon_modify_mem_list
[bb
] =
2465 alloc_INSN_LIST (insn
, canon_modify_mem_list
[bb
]);
2466 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2469 note_stores (PATTERN (insn
), canon_list_insert
, (void*) insn
);
2472 /* Called from compute_hash_table via note_stores to handle one
2473 SET or CLOBBER in an insn. DATA is really the instruction in which
2474 the SET is taking place. */
2477 record_last_set_info (dest
, setter
, data
)
2478 rtx dest
, setter ATTRIBUTE_UNUSED
;
2481 rtx last_set_insn
= (rtx
) data
;
2483 if (GET_CODE (dest
) == SUBREG
)
2484 dest
= SUBREG_REG (dest
);
2486 if (GET_CODE (dest
) == REG
)
2487 record_last_reg_set_info (last_set_insn
, REGNO (dest
));
2488 else if (GET_CODE (dest
) == MEM
2489 /* Ignore pushes, they clobber nothing. */
2490 && ! push_operand (dest
, GET_MODE (dest
)))
2491 record_last_mem_set_info (last_set_insn
);
2494 /* Top level function to create an expression or assignment hash table.
2496 Expression entries are placed in the hash table if
2497 - they are of the form (set (pseudo-reg) src),
2498 - src is something we want to perform GCSE on,
2499 - none of the operands are subsequently modified in the block
2501 Assignment entries are placed in the hash table if
2502 - they are of the form (set (pseudo-reg) src),
2503 - src is something we want to perform const/copy propagation on,
2504 - none of the operands or target are subsequently modified in the block
2506 Currently src must be a pseudo-reg or a const_int.
2508 TABLE is the table computed. */
2511 compute_hash_table_work (table
)
2512 struct hash_table
*table
;
2516 /* While we compute the hash table we also compute a bit array of which
2517 registers are set in which blocks.
2518 ??? This isn't needed during const/copy propagation, but it's cheap to
2520 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
2522 /* re-Cache any INSN_LIST nodes we have allocated. */
2523 clear_modify_mem_tables ();
2524 /* Some working arrays used to track first and last set in each block. */
2525 reg_avail_info
= (struct reg_avail_info
*)
2526 gmalloc (max_gcse_regno
* sizeof (struct reg_avail_info
));
2528 for (i
= 0; i
< max_gcse_regno
; ++i
)
2529 reg_avail_info
[i
].last_bb
= NULL
;
2531 FOR_EACH_BB (current_bb
)
2535 int in_libcall_block
;
2537 /* First pass over the instructions records information used to
2538 determine when registers and memory are first and last set.
2539 ??? hard-reg reg_set_in_block computation
2540 could be moved to compute_sets since they currently don't change. */
2542 for (insn
= current_bb
->head
;
2543 insn
&& insn
!= NEXT_INSN (current_bb
->end
);
2544 insn
= NEXT_INSN (insn
))
2546 if (! INSN_P (insn
))
2549 if (GET_CODE (insn
) == CALL_INSN
)
2551 bool clobbers_all
= false;
2552 #ifdef NON_SAVING_SETJMP
2553 if (NON_SAVING_SETJMP
2554 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
2555 clobbers_all
= true;
2558 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2560 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2561 record_last_reg_set_info (insn
, regno
);
2566 note_stores (PATTERN (insn
), record_last_set_info
, insn
);
2569 /* Insert implicit sets in the hash table. */
2571 && implicit_sets
[current_bb
->index
] != NULL_RTX
)
2572 hash_scan_set (implicit_sets
[current_bb
->index
],
2573 current_bb
->head
, table
);
2575 /* The next pass builds the hash table. */
2577 for (insn
= current_bb
->head
, in_libcall_block
= 0;
2578 insn
&& insn
!= NEXT_INSN (current_bb
->end
);
2579 insn
= NEXT_INSN (insn
))
2582 if (find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2583 in_libcall_block
= 1;
2584 else if (table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2585 in_libcall_block
= 0;
2586 hash_scan_insn (insn
, table
, in_libcall_block
);
2587 if (!table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2588 in_libcall_block
= 0;
2592 free (reg_avail_info
);
2593 reg_avail_info
= NULL
;
2596 /* Allocate space for the set/expr hash TABLE.
2597 N_INSNS is the number of instructions in the function.
2598 It is used to determine the number of buckets to use.
2599 SET_P determines whether set or expression table will
2603 alloc_hash_table (n_insns
, table
, set_p
)
2605 struct hash_table
*table
;
2610 table
->size
= n_insns
/ 4;
2611 if (table
->size
< 11)
2614 /* Attempt to maintain efficient use of hash table.
2615 Making it an odd number is simplest for now.
2616 ??? Later take some measurements. */
2618 n
= table
->size
* sizeof (struct expr
*);
2619 table
->table
= (struct expr
**) gmalloc (n
);
2620 table
->set_p
= set_p
;
2623 /* Free things allocated by alloc_hash_table. */
2626 free_hash_table (table
)
2627 struct hash_table
*table
;
2629 free (table
->table
);
2632 /* Compute the hash TABLE for doing copy/const propagation or
2633 expression hash table. */
2636 compute_hash_table (table
)
2637 struct hash_table
*table
;
2639 /* Initialize count of number of entries in hash table. */
2641 memset ((char *) table
->table
, 0,
2642 table
->size
* sizeof (struct expr
*));
2644 compute_hash_table_work (table
);
2647 /* Expression tracking support. */
2649 /* Lookup pattern PAT in the expression TABLE.
2650 The result is a pointer to the table entry, or NULL if not found. */
2652 static struct expr
*
2653 lookup_expr (pat
, table
)
2655 struct hash_table
*table
;
2657 int do_not_record_p
;
2658 unsigned int hash
= hash_expr (pat
, GET_MODE (pat
), &do_not_record_p
,
2662 if (do_not_record_p
)
2665 expr
= table
->table
[hash
];
2667 while (expr
&& ! expr_equiv_p (expr
->expr
, pat
))
2668 expr
= expr
->next_same_hash
;
2673 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2674 table entry, or NULL if not found. */
2676 static struct expr
*
2677 lookup_set (regno
, table
)
2679 struct hash_table
*table
;
2681 unsigned int hash
= hash_set (regno
, table
->size
);
2684 expr
= table
->table
[hash
];
2686 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
)
2687 expr
= expr
->next_same_hash
;
2692 /* Return the next entry for REGNO in list EXPR. */
2694 static struct expr
*
2695 next_set (regno
, expr
)
2700 expr
= expr
->next_same_hash
;
2701 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
);
2706 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2707 types may be mixed. */
2710 free_insn_expr_list_list (listp
)
2715 for (list
= *listp
; list
; list
= next
)
2717 next
= XEXP (list
, 1);
2718 if (GET_CODE (list
) == EXPR_LIST
)
2719 free_EXPR_LIST_node (list
);
2721 free_INSN_LIST_node (list
);
2727 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2729 clear_modify_mem_tables ()
2733 EXECUTE_IF_SET_IN_BITMAP
2734 (modify_mem_list_set
, 0, i
, free_INSN_LIST_list (modify_mem_list
+ i
));
2735 bitmap_clear (modify_mem_list_set
);
2737 EXECUTE_IF_SET_IN_BITMAP
2738 (canon_modify_mem_list_set
, 0, i
,
2739 free_insn_expr_list_list (canon_modify_mem_list
+ i
));
2740 bitmap_clear (canon_modify_mem_list_set
);
2743 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2746 free_modify_mem_tables ()
2748 clear_modify_mem_tables ();
2749 free (modify_mem_list
);
2750 free (canon_modify_mem_list
);
2751 modify_mem_list
= 0;
2752 canon_modify_mem_list
= 0;
2755 /* Reset tables used to keep track of what's still available [since the
2756 start of the block]. */
2759 reset_opr_set_tables ()
2761 /* Maintain a bitmap of which regs have been set since beginning of
2763 CLEAR_REG_SET (reg_set_bitmap
);
2765 /* Also keep a record of the last instruction to modify memory.
2766 For now this is very trivial, we only record whether any memory
2767 location has been modified. */
2768 clear_modify_mem_tables ();
2771 /* Return nonzero if the operands of X are not set before INSN in
2772 INSN's basic block. */
2775 oprs_not_set_p (x
, insn
)
2785 code
= GET_CODE (x
);
2801 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn
),
2802 INSN_CUID (insn
), x
, 0))
2805 return oprs_not_set_p (XEXP (x
, 0), insn
);
2808 return ! REGNO_REG_SET_P (reg_set_bitmap
, REGNO (x
));
2814 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2818 /* If we are about to do the last recursive call
2819 needed at this level, change it into iteration.
2820 This function is called enough to be worth it. */
2822 return oprs_not_set_p (XEXP (x
, i
), insn
);
2824 if (! oprs_not_set_p (XEXP (x
, i
), insn
))
2827 else if (fmt
[i
] == 'E')
2828 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2829 if (! oprs_not_set_p (XVECEXP (x
, i
, j
), insn
))
2836 /* Mark things set by a CALL. */
2842 if (! CONST_OR_PURE_CALL_P (insn
))
2843 record_last_mem_set_info (insn
);
2846 /* Mark things set by a SET. */
2849 mark_set (pat
, insn
)
2852 rtx dest
= SET_DEST (pat
);
2854 while (GET_CODE (dest
) == SUBREG
2855 || GET_CODE (dest
) == ZERO_EXTRACT
2856 || GET_CODE (dest
) == SIGN_EXTRACT
2857 || GET_CODE (dest
) == STRICT_LOW_PART
)
2858 dest
= XEXP (dest
, 0);
2860 if (GET_CODE (dest
) == REG
)
2861 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (dest
));
2862 else if (GET_CODE (dest
) == MEM
)
2863 record_last_mem_set_info (insn
);
2865 if (GET_CODE (SET_SRC (pat
)) == CALL
)
2869 /* Record things set by a CLOBBER. */
2872 mark_clobber (pat
, insn
)
2875 rtx clob
= XEXP (pat
, 0);
2877 while (GET_CODE (clob
) == SUBREG
|| GET_CODE (clob
) == STRICT_LOW_PART
)
2878 clob
= XEXP (clob
, 0);
2880 if (GET_CODE (clob
) == REG
)
2881 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (clob
));
2883 record_last_mem_set_info (insn
);
2886 /* Record things set by INSN.
2887 This data is used by oprs_not_set_p. */
2890 mark_oprs_set (insn
)
2893 rtx pat
= PATTERN (insn
);
2896 if (GET_CODE (pat
) == SET
)
2897 mark_set (pat
, insn
);
2898 else if (GET_CODE (pat
) == PARALLEL
)
2899 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2901 rtx x
= XVECEXP (pat
, 0, i
);
2903 if (GET_CODE (x
) == SET
)
2905 else if (GET_CODE (x
) == CLOBBER
)
2906 mark_clobber (x
, insn
);
2907 else if (GET_CODE (x
) == CALL
)
2911 else if (GET_CODE (pat
) == CLOBBER
)
2912 mark_clobber (pat
, insn
);
2913 else if (GET_CODE (pat
) == CALL
)
2918 /* Classic GCSE reaching definition support. */
2920 /* Allocate reaching def variables. */
2923 alloc_rd_mem (n_blocks
, n_insns
)
2924 int n_blocks
, n_insns
;
2926 rd_kill
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2927 sbitmap_vector_zero (rd_kill
, n_blocks
);
2929 rd_gen
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2930 sbitmap_vector_zero (rd_gen
, n_blocks
);
2932 reaching_defs
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2933 sbitmap_vector_zero (reaching_defs
, n_blocks
);
2935 rd_out
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2936 sbitmap_vector_zero (rd_out
, n_blocks
);
2939 /* Free reaching def variables. */
2944 sbitmap_vector_free (rd_kill
);
2945 sbitmap_vector_free (rd_gen
);
2946 sbitmap_vector_free (reaching_defs
);
2947 sbitmap_vector_free (rd_out
);
2950 /* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
2953 handle_rd_kill_set (insn
, regno
, bb
)
2958 struct reg_set
*this_reg
;
2960 for (this_reg
= reg_set_table
[regno
]; this_reg
; this_reg
= this_reg
->next
)
2961 if (BLOCK_NUM (this_reg
->insn
) != BLOCK_NUM (insn
))
2962 SET_BIT (rd_kill
[bb
->index
], INSN_CUID (this_reg
->insn
));
2965 /* Compute the set of kill's for reaching definitions. */
2976 For each set bit in `gen' of the block (i.e each insn which
2977 generates a definition in the block)
2978 Call the reg set by the insn corresponding to that bit regx
2979 Look at the linked list starting at reg_set_table[regx]
2980 For each setting of regx in the linked list, which is not in
2982 Set the bit in `kill' corresponding to that insn. */
2984 for (cuid
= 0; cuid
< max_cuid
; cuid
++)
2985 if (TEST_BIT (rd_gen
[bb
->index
], cuid
))
2987 rtx insn
= CUID_INSN (cuid
);
2988 rtx pat
= PATTERN (insn
);
2990 if (GET_CODE (insn
) == CALL_INSN
)
2992 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2993 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2994 handle_rd_kill_set (insn
, regno
, bb
);
2997 if (GET_CODE (pat
) == PARALLEL
)
2999 for (i
= XVECLEN (pat
, 0) - 1; i
>= 0; i
--)
3001 enum rtx_code code
= GET_CODE (XVECEXP (pat
, 0, i
));
3003 if ((code
== SET
|| code
== CLOBBER
)
3004 && GET_CODE (XEXP (XVECEXP (pat
, 0, i
), 0)) == REG
)
3005 handle_rd_kill_set (insn
,
3006 REGNO (XEXP (XVECEXP (pat
, 0, i
), 0)),
3010 else if (GET_CODE (pat
) == SET
&& GET_CODE (SET_DEST (pat
)) == REG
)
3011 /* Each setting of this register outside of this block
3012 must be marked in the set of kills in this block. */
3013 handle_rd_kill_set (insn
, REGNO (SET_DEST (pat
)), bb
);
3017 /* Compute the reaching definitions as in
3018 Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
3019 Chapter 10. It is the same algorithm as used for computing available
3020 expressions but applied to the gens and kills of reaching definitions. */
3025 int changed
, passes
;
3029 sbitmap_copy (rd_out
[bb
->index
] /*dst*/, rd_gen
[bb
->index
] /*src*/);
3038 sbitmap_union_of_preds (reaching_defs
[bb
->index
], rd_out
, bb
->index
);
3039 changed
|= sbitmap_union_of_diff_cg (rd_out
[bb
->index
], rd_gen
[bb
->index
],
3040 reaching_defs
[bb
->index
], rd_kill
[bb
->index
]);
3046 fprintf (gcse_file
, "reaching def computation: %d passes\n", passes
);
3049 /* Classic GCSE available expression support. */
3051 /* Allocate memory for available expression computation. */
3054 alloc_avail_expr_mem (n_blocks
, n_exprs
)
3055 int n_blocks
, n_exprs
;
3057 ae_kill
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3058 sbitmap_vector_zero (ae_kill
, n_blocks
);
3060 ae_gen
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3061 sbitmap_vector_zero (ae_gen
, n_blocks
);
3063 ae_in
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3064 sbitmap_vector_zero (ae_in
, n_blocks
);
3066 ae_out
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3067 sbitmap_vector_zero (ae_out
, n_blocks
);
3071 free_avail_expr_mem ()
3073 sbitmap_vector_free (ae_kill
);
3074 sbitmap_vector_free (ae_gen
);
3075 sbitmap_vector_free (ae_in
);
3076 sbitmap_vector_free (ae_out
);
3079 /* Compute the set of available expressions generated in each basic block. */
3082 compute_ae_gen (expr_hash_table
)
3083 struct hash_table
*expr_hash_table
;
3089 /* For each recorded occurrence of each expression, set ae_gen[bb][expr].
3090 This is all we have to do because an expression is not recorded if it
3091 is not available, and the only expressions we want to work with are the
3092 ones that are recorded. */
3093 for (i
= 0; i
< expr_hash_table
->size
; i
++)
3094 for (expr
= expr_hash_table
->table
[i
]; expr
!= 0; expr
= expr
->next_same_hash
)
3095 for (occr
= expr
->avail_occr
; occr
!= 0; occr
= occr
->next
)
3096 SET_BIT (ae_gen
[BLOCK_NUM (occr
->insn
)], expr
->bitmap_index
);
3099 /* Return nonzero if expression X is killed in BB. */
3102 expr_killed_p (x
, bb
)
3113 code
= GET_CODE (x
);
3117 return TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
));
3120 if (load_killed_in_block_p (bb
, get_max_uid () + 1, x
, 0))
3123 return expr_killed_p (XEXP (x
, 0), bb
);
3141 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3145 /* If we are about to do the last recursive call
3146 needed at this level, change it into iteration.
3147 This function is called enough to be worth it. */
3149 return expr_killed_p (XEXP (x
, i
), bb
);
3150 else if (expr_killed_p (XEXP (x
, i
), bb
))
3153 else if (fmt
[i
] == 'E')
3154 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3155 if (expr_killed_p (XVECEXP (x
, i
, j
), bb
))
3162 /* Compute the set of available expressions killed in each basic block. */
3165 compute_ae_kill (ae_gen
, ae_kill
, expr_hash_table
)
3166 sbitmap
*ae_gen
, *ae_kill
;
3167 struct hash_table
*expr_hash_table
;
3174 for (i
= 0; i
< expr_hash_table
->size
; i
++)
3175 for (expr
= expr_hash_table
->table
[i
]; expr
; expr
= expr
->next_same_hash
)
3177 /* Skip EXPR if generated in this block. */
3178 if (TEST_BIT (ae_gen
[bb
->index
], expr
->bitmap_index
))
3181 if (expr_killed_p (expr
->expr
, bb
))
3182 SET_BIT (ae_kill
[bb
->index
], expr
->bitmap_index
);
3186 /* Actually perform the Classic GCSE optimizations. */
3188 /* Return nonzero if occurrence OCCR of expression EXPR reaches block BB.
3190 CHECK_SELF_LOOP is nonzero if we should consider a block reaching itself
3191 as a positive reach. We want to do this when there are two computations
3192 of the expression in the block.
3194 VISITED is a pointer to a working buffer for tracking which BB's have
3195 been visited. It is NULL for the top-level call.
3197 We treat reaching expressions that go through blocks containing the same
3198 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3199 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3200 2 as not reaching. The intent is to improve the probability of finding
3201 only one reaching expression and to reduce register lifetimes by picking
3202 the closest such expression. */
3205 expr_reaches_here_p_work (occr
, expr
, bb
, check_self_loop
, visited
)
3209 int check_self_loop
;
3214 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
3216 basic_block pred_bb
= pred
->src
;
3218 if (visited
[pred_bb
->index
])
3219 /* This predecessor has already been visited. Nothing to do. */
3221 else if (pred_bb
== bb
)
3223 /* BB loops on itself. */
3225 && TEST_BIT (ae_gen
[pred_bb
->index
], expr
->bitmap_index
)
3226 && BLOCK_NUM (occr
->insn
) == pred_bb
->index
)
3229 visited
[pred_bb
->index
] = 1;
3232 /* Ignore this predecessor if it kills the expression. */
3233 else if (TEST_BIT (ae_kill
[pred_bb
->index
], expr
->bitmap_index
))
3234 visited
[pred_bb
->index
] = 1;
3236 /* Does this predecessor generate this expression? */
3237 else if (TEST_BIT (ae_gen
[pred_bb
->index
], expr
->bitmap_index
))
3239 /* Is this the occurrence we're looking for?
3240 Note that there's only one generating occurrence per block
3241 so we just need to check the block number. */
3242 if (BLOCK_NUM (occr
->insn
) == pred_bb
->index
)
3245 visited
[pred_bb
->index
] = 1;
3248 /* Neither gen nor kill. */
3251 visited
[pred_bb
->index
] = 1;
3252 if (expr_reaches_here_p_work (occr
, expr
, pred_bb
, check_self_loop
,
3259 /* All paths have been checked. */
3263 /* This wrapper for expr_reaches_here_p_work() is to ensure that any
3264 memory allocated for that function is returned. */
3267 expr_reaches_here_p (occr
, expr
, bb
, check_self_loop
)
3271 int check_self_loop
;
3274 char *visited
= (char *) xcalloc (last_basic_block
, 1);
3276 rval
= expr_reaches_here_p_work (occr
, expr
, bb
, check_self_loop
, visited
);
3282 /* Return the instruction that computes EXPR that reaches INSN's basic block.
3283 If there is more than one such instruction, return NULL.
3285 Called only by handle_avail_expr. */
3288 computing_insn (expr
, insn
)
3292 basic_block bb
= BLOCK_FOR_INSN (insn
);
3294 if (expr
->avail_occr
->next
== NULL
)
3296 if (BLOCK_FOR_INSN (expr
->avail_occr
->insn
) == bb
)
3297 /* The available expression is actually itself
3298 (i.e. a loop in the flow graph) so do nothing. */
3301 /* (FIXME) Case that we found a pattern that was created by
3302 a substitution that took place. */
3303 return expr
->avail_occr
->insn
;
3307 /* Pattern is computed more than once.
3308 Search backwards from this insn to see how many of these
3309 computations actually reach this insn. */
3311 rtx insn_computes_expr
= NULL
;
3314 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
3316 if (BLOCK_FOR_INSN (occr
->insn
) == bb
)
3318 /* The expression is generated in this block.
3319 The only time we care about this is when the expression
3320 is generated later in the block [and thus there's a loop].
3321 We let the normal cse pass handle the other cases. */
3322 if (INSN_CUID (insn
) < INSN_CUID (occr
->insn
)
3323 && expr_reaches_here_p (occr
, expr
, bb
, 1))
3329 insn_computes_expr
= occr
->insn
;
3332 else if (expr_reaches_here_p (occr
, expr
, bb
, 0))
3338 insn_computes_expr
= occr
->insn
;
3342 if (insn_computes_expr
== NULL
)
3345 return insn_computes_expr
;
3349 /* Return nonzero if the definition in DEF_INSN can reach INSN.
3350 Only called by can_disregard_other_sets. */
3353 def_reaches_here_p (insn
, def_insn
)
3358 if (TEST_BIT (reaching_defs
[BLOCK_NUM (insn
)], INSN_CUID (def_insn
)))
3361 if (BLOCK_NUM (insn
) == BLOCK_NUM (def_insn
))
3363 if (INSN_CUID (def_insn
) < INSN_CUID (insn
))
3365 if (GET_CODE (PATTERN (def_insn
)) == PARALLEL
)
3367 else if (GET_CODE (PATTERN (def_insn
)) == CLOBBER
)
3368 reg
= XEXP (PATTERN (def_insn
), 0);
3369 else if (GET_CODE (PATTERN (def_insn
)) == SET
)
3370 reg
= SET_DEST (PATTERN (def_insn
));
3374 return ! reg_set_between_p (reg
, NEXT_INSN (def_insn
), insn
);
3383 /* Return nonzero if *ADDR_THIS_REG can only have one value at INSN. The
3384 value returned is the number of definitions that reach INSN. Returning a
3385 value of zero means that [maybe] more than one definition reaches INSN and
3386 the caller can't perform whatever optimization it is trying. i.e. it is
3387 always safe to return zero. */
3390 can_disregard_other_sets (addr_this_reg
, insn
, for_combine
)
3391 struct reg_set
**addr_this_reg
;
3395 int number_of_reaching_defs
= 0;
3396 struct reg_set
*this_reg
;
3398 for (this_reg
= *addr_this_reg
; this_reg
!= 0; this_reg
= this_reg
->next
)
3399 if (def_reaches_here_p (insn
, this_reg
->insn
))
3401 number_of_reaching_defs
++;
3402 /* Ignore parallels for now. */
3403 if (GET_CODE (PATTERN (this_reg
->insn
)) == PARALLEL
)
3407 && (GET_CODE (PATTERN (this_reg
->insn
)) == CLOBBER
3408 || ! rtx_equal_p (SET_SRC (PATTERN (this_reg
->insn
)),
3409 SET_SRC (PATTERN (insn
)))))
3410 /* A setting of the reg to a different value reaches INSN. */
3413 if (number_of_reaching_defs
> 1)
3415 /* If in this setting the value the register is being set to is
3416 equal to the previous value the register was set to and this
3417 setting reaches the insn we are trying to do the substitution
3418 on then we are ok. */
3419 if (GET_CODE (PATTERN (this_reg
->insn
)) == CLOBBER
)
3421 else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg
->insn
)),
3422 SET_SRC (PATTERN (insn
))))
3426 *addr_this_reg
= this_reg
;
3429 return number_of_reaching_defs
;
3432 /* Expression computed by insn is available and the substitution is legal,
3433 so try to perform the substitution.
3435 The result is nonzero if any changes were made. */
3438 handle_avail_expr (insn
, expr
)
3442 rtx pat
, insn_computes_expr
, expr_set
;
3444 struct reg_set
*this_reg
;
3445 int found_setting
, use_src
;
3448 /* We only handle the case where one computation of the expression
3449 reaches this instruction. */
3450 insn_computes_expr
= computing_insn (expr
, insn
);
3451 if (insn_computes_expr
== NULL
)
3453 expr_set
= single_set (insn_computes_expr
);
3460 /* At this point we know only one computation of EXPR outside of this
3461 block reaches this insn. Now try to find a register that the
3462 expression is computed into. */
3463 if (GET_CODE (SET_SRC (expr_set
)) == REG
)
3465 /* This is the case when the available expression that reaches
3466 here has already been handled as an available expression. */
3467 unsigned int regnum_for_replacing
3468 = REGNO (SET_SRC (expr_set
));
3470 /* If the register was created by GCSE we can't use `reg_set_table',
3471 however we know it's set only once. */
3472 if (regnum_for_replacing
>= max_gcse_regno
3473 /* If the register the expression is computed into is set only once,
3474 or only one set reaches this insn, we can use it. */
3475 || (((this_reg
= reg_set_table
[regnum_for_replacing
]),
3476 this_reg
->next
== NULL
)
3477 || can_disregard_other_sets (&this_reg
, insn
, 0)))
3486 unsigned int regnum_for_replacing
3487 = REGNO (SET_DEST (expr_set
));
3489 /* This shouldn't happen. */
3490 if (regnum_for_replacing
>= max_gcse_regno
)
3493 this_reg
= reg_set_table
[regnum_for_replacing
];
3495 /* If the register the expression is computed into is set only once,
3496 or only one set reaches this insn, use it. */
3497 if (this_reg
->next
== NULL
3498 || can_disregard_other_sets (&this_reg
, insn
, 0))
3504 pat
= PATTERN (insn
);
3506 to
= SET_SRC (expr_set
);
3508 to
= SET_DEST (expr_set
);
3509 changed
= validate_change (insn
, &SET_SRC (pat
), to
, 0);
3511 /* We should be able to ignore the return code from validate_change but
3512 to play it safe we check. */
3516 if (gcse_file
!= NULL
)
3518 fprintf (gcse_file
, "GCSE: Replacing the source in insn %d with",
3520 fprintf (gcse_file
, " reg %d %s insn %d\n",
3521 REGNO (to
), use_src
? "from" : "set in",
3522 INSN_UID (insn_computes_expr
));
3527 /* The register that the expr is computed into is set more than once. */
3528 else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
3530 /* Insert an insn after insnx that copies the reg set in insnx
3531 into a new pseudo register call this new register REGN.
3532 From insnb until end of basic block or until REGB is set
3533 replace all uses of REGB with REGN. */
3536 to
= gen_reg_rtx (GET_MODE (SET_DEST (expr_set
)));
3538 /* Generate the new insn. */
3539 /* ??? If the change fails, we return 0, even though we created
3540 an insn. I think this is ok. */
3542 = emit_insn_after (gen_rtx_SET (VOIDmode
, to
,
3543 SET_DEST (expr_set
)),
3544 insn_computes_expr
);
3546 /* Keep register set table up to date. */
3547 record_one_set (REGNO (to
), new_insn
);
3549 gcse_create_count
++;
3550 if (gcse_file
!= NULL
)
3552 fprintf (gcse_file
, "GCSE: Creating insn %d to copy value of reg %d",
3553 INSN_UID (NEXT_INSN (insn_computes_expr
)),
3554 REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr
)))));
3555 fprintf (gcse_file
, ", computed in insn %d,\n",
3556 INSN_UID (insn_computes_expr
));
3557 fprintf (gcse_file
, " into newly allocated reg %d\n",
3561 pat
= PATTERN (insn
);
3563 /* Do register replacement for INSN. */
3564 changed
= validate_change (insn
, &SET_SRC (pat
),
3566 (NEXT_INSN (insn_computes_expr
))),
3569 /* We should be able to ignore the return code from validate_change but
3570 to play it safe we check. */
3574 if (gcse_file
!= NULL
)
3577 "GCSE: Replacing the source in insn %d with reg %d ",
3579 REGNO (SET_DEST (PATTERN (NEXT_INSN
3580 (insn_computes_expr
)))));
3581 fprintf (gcse_file
, "set in insn %d\n",
3582 INSN_UID (insn_computes_expr
));
3590 /* Perform classic GCSE. This is called by one_classic_gcse_pass after all
3591 the dataflow analysis has been done.
3593 The result is nonzero if a change was made. */
3602 /* Note we start at block 1. */
3604 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3608 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
3610 /* Reset tables used to keep track of what's still valid [since the
3611 start of the block]. */
3612 reset_opr_set_tables ();
3614 for (insn
= bb
->head
;
3615 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
3616 insn
= NEXT_INSN (insn
))
3618 /* Is insn of form (set (pseudo-reg) ...)? */
3619 if (GET_CODE (insn
) == INSN
3620 && GET_CODE (PATTERN (insn
)) == SET
3621 && GET_CODE (SET_DEST (PATTERN (insn
))) == REG
3622 && REGNO (SET_DEST (PATTERN (insn
))) >= FIRST_PSEUDO_REGISTER
)
3624 rtx pat
= PATTERN (insn
);
3625 rtx src
= SET_SRC (pat
);
3628 if (want_to_gcse_p (src
)
3629 /* Is the expression recorded? */
3630 && ((expr
= lookup_expr (src
, &expr_hash_table
)) != NULL
)
3631 /* Is the expression available [at the start of the
3633 && TEST_BIT (ae_in
[bb
->index
], expr
->bitmap_index
)
3634 /* Are the operands unchanged since the start of the
3636 && oprs_not_set_p (src
, insn
))
3637 changed
|= handle_avail_expr (insn
, expr
);
3640 /* Keep track of everything modified by this insn. */
3641 /* ??? Need to be careful w.r.t. mods done to INSN. */
3643 mark_oprs_set (insn
);
3650 /* Top level routine to perform one classic GCSE pass.
3652 Return nonzero if a change was made. */
3655 one_classic_gcse_pass (pass
)
3660 gcse_subst_count
= 0;
3661 gcse_create_count
= 0;
3663 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
3664 alloc_rd_mem (last_basic_block
, max_cuid
);
3665 compute_hash_table (&expr_hash_table
);
3667 dump_hash_table (gcse_file
, "Expression", &expr_hash_table
);
3669 if (expr_hash_table
.n_elems
> 0)
3673 alloc_avail_expr_mem (last_basic_block
, expr_hash_table
.n_elems
);
3674 compute_ae_gen (&expr_hash_table
);
3675 compute_ae_kill (ae_gen
, ae_kill
, &expr_hash_table
);
3676 compute_available (ae_gen
, ae_kill
, ae_out
, ae_in
);
3677 changed
= classic_gcse ();
3678 free_avail_expr_mem ();
3682 free_hash_table (&expr_hash_table
);
3686 fprintf (gcse_file
, "\n");
3687 fprintf (gcse_file
, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
3688 current_function_name
, pass
, bytes_used
, gcse_subst_count
);
3689 fprintf (gcse_file
, "%d insns created\n", gcse_create_count
);
3695 /* Compute copy/constant propagation working variables. */
3697 /* Local properties of assignments. */
3698 static sbitmap
*cprop_pavloc
;
3699 static sbitmap
*cprop_absaltered
;
3701 /* Global properties of assignments (computed from the local properties). */
3702 static sbitmap
*cprop_avin
;
3703 static sbitmap
*cprop_avout
;
3705 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
3706 basic blocks. N_SETS is the number of sets. */
3709 alloc_cprop_mem (n_blocks
, n_sets
)
3710 int n_blocks
, n_sets
;
3712 cprop_pavloc
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3713 cprop_absaltered
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3715 cprop_avin
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3716 cprop_avout
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3719 /* Free vars used by copy/const propagation. */
3724 sbitmap_vector_free (cprop_pavloc
);
3725 sbitmap_vector_free (cprop_absaltered
);
3726 sbitmap_vector_free (cprop_avin
);
3727 sbitmap_vector_free (cprop_avout
);
3730 /* For each block, compute whether X is transparent. X is either an
3731 expression or an assignment [though we don't care which, for this context
3732 an assignment is treated as an expression]. For each block where an
3733 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
3737 compute_transp (x
, indx
, bmap
, set_p
)
3749 /* repeat is used to turn tail-recursion into iteration since GCC
3750 can't do it when there's no return value. */
3756 code
= GET_CODE (x
);
3762 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
3765 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
3766 SET_BIT (bmap
[bb
->index
], indx
);
3770 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
3771 SET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
3776 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
3779 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
3780 RESET_BIT (bmap
[bb
->index
], indx
);
3784 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
3785 RESET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
3794 rtx list_entry
= canon_modify_mem_list
[bb
->index
];
3798 rtx dest
, dest_addr
;
3800 if (GET_CODE (XEXP (list_entry
, 0)) == CALL_INSN
)
3803 SET_BIT (bmap
[bb
->index
], indx
);
3805 RESET_BIT (bmap
[bb
->index
], indx
);
3808 /* LIST_ENTRY must be an INSN of some kind that sets memory.
3809 Examine each hunk of memory that is modified. */
3811 dest
= XEXP (list_entry
, 0);
3812 list_entry
= XEXP (list_entry
, 1);
3813 dest_addr
= XEXP (list_entry
, 0);
3815 if (canon_true_dependence (dest
, GET_MODE (dest
), dest_addr
,
3816 x
, rtx_addr_varies_p
))
3819 SET_BIT (bmap
[bb
->index
], indx
);
3821 RESET_BIT (bmap
[bb
->index
], indx
);
3824 list_entry
= XEXP (list_entry
, 1);
3847 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3851 /* If we are about to do the last recursive call
3852 needed at this level, change it into iteration.
3853 This function is called enough to be worth it. */
3860 compute_transp (XEXP (x
, i
), indx
, bmap
, set_p
);
3862 else if (fmt
[i
] == 'E')
3863 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3864 compute_transp (XVECEXP (x
, i
, j
), indx
, bmap
, set_p
);
3868 /* Top level routine to do the dataflow analysis needed by copy/const
3872 compute_cprop_data ()
3874 compute_local_properties (cprop_absaltered
, cprop_pavloc
, NULL
, &set_hash_table
);
3875 compute_available (cprop_pavloc
, cprop_absaltered
,
3876 cprop_avout
, cprop_avin
);
3879 /* Copy/constant propagation. */
3881 /* Maximum number of register uses in an insn that we handle. */
3884 /* Table of uses found in an insn.
3885 Allocated statically to avoid alloc/free complexity and overhead. */
3886 static struct reg_use reg_use_table
[MAX_USES
];
3888 /* Index into `reg_use_table' while building it. */
3889 static int reg_use_count
;
3891 /* Set up a list of register numbers used in INSN. The found uses are stored
3892 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
3893 and contains the number of uses in the table upon exit.
3895 ??? If a register appears multiple times we will record it multiple times.
3896 This doesn't hurt anything but it will slow things down. */
3899 find_used_regs (xptr
, data
)
3901 void *data ATTRIBUTE_UNUSED
;
3908 /* repeat is used to turn tail-recursion into iteration since GCC
3909 can't do it when there's no return value. */
3914 code
= GET_CODE (x
);
3917 if (reg_use_count
== MAX_USES
)
3920 reg_use_table
[reg_use_count
].reg_rtx
= x
;
3924 /* Recursively scan the operands of this expression. */
3926 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3930 /* If we are about to do the last recursive call
3931 needed at this level, change it into iteration.
3932 This function is called enough to be worth it. */
3939 find_used_regs (&XEXP (x
, i
), data
);
3941 else if (fmt
[i
] == 'E')
3942 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3943 find_used_regs (&XVECEXP (x
, i
, j
), data
);
3947 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
3948 Returns nonzero is successful. */
3951 try_replace_reg (from
, to
, insn
)
3954 rtx note
= find_reg_equal_equiv_note (insn
);
3957 rtx set
= single_set (insn
);
3959 validate_replace_src_group (from
, to
, insn
);
3960 if (num_changes_pending () && apply_change_group ())
3963 /* Try to simplify SET_SRC if we have substituted a constant. */
3964 if (success
&& set
&& CONSTANT_P (to
))
3966 src
= simplify_rtx (SET_SRC (set
));
3969 validate_change (insn
, &SET_SRC (set
), src
, 0);
3972 if (!success
&& set
&& reg_mentioned_p (from
, SET_SRC (set
)))
3974 /* If above failed and this is a single set, try to simplify the source of
3975 the set given our substitution. We could perhaps try this for multiple
3976 SETs, but it probably won't buy us anything. */
3977 src
= simplify_replace_rtx (SET_SRC (set
), from
, to
);
3979 if (!rtx_equal_p (src
, SET_SRC (set
))
3980 && validate_change (insn
, &SET_SRC (set
), src
, 0))
3983 /* If we've failed to do replacement, have a single SET, and don't already
3984 have a note, add a REG_EQUAL note to not lose information. */
3985 if (!success
&& note
== 0 && set
!= 0)
3986 note
= set_unique_reg_note (insn
, REG_EQUAL
, copy_rtx (src
));
3989 /* If there is already a NOTE, update the expression in it with our
3992 XEXP (note
, 0) = simplify_replace_rtx (XEXP (note
, 0), from
, to
);
3994 /* REG_EQUAL may get simplified into register.
3995 We don't allow that. Remove that note. This code ought
3996 not to happen, because previous code ought to synthesize
3997 reg-reg move, but be on the safe side. */
3998 if (note
&& REG_P (XEXP (note
, 0)))
3999 remove_note (insn
, note
);
4004 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
4005 NULL no such set is found. */
4007 static struct expr
*
4008 find_avail_set (regno
, insn
)
4012 /* SET1 contains the last set found that can be returned to the caller for
4013 use in a substitution. */
4014 struct expr
*set1
= 0;
4016 /* Loops are not possible here. To get a loop we would need two sets
4017 available at the start of the block containing INSN. ie we would
4018 need two sets like this available at the start of the block:
4020 (set (reg X) (reg Y))
4021 (set (reg Y) (reg X))
4023 This can not happen since the set of (reg Y) would have killed the
4024 set of (reg X) making it unavailable at the start of this block. */
4028 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
4030 /* Find a set that is available at the start of the block
4031 which contains INSN. */
4034 if (TEST_BIT (cprop_avin
[BLOCK_NUM (insn
)], set
->bitmap_index
))
4036 set
= next_set (regno
, set
);
4039 /* If no available set was found we've reached the end of the
4040 (possibly empty) copy chain. */
4044 if (GET_CODE (set
->expr
) != SET
)
4047 src
= SET_SRC (set
->expr
);
4049 /* We know the set is available.
4050 Now check that SRC is ANTLOC (i.e. none of the source operands
4051 have changed since the start of the block).
4053 If the source operand changed, we may still use it for the next
4054 iteration of this loop, but we may not use it for substitutions. */
4056 if (gcse_constant_p (src
) || oprs_not_set_p (src
, insn
))
4059 /* If the source of the set is anything except a register, then
4060 we have reached the end of the copy chain. */
4061 if (GET_CODE (src
) != REG
)
4064 /* Follow the copy chain, ie start another iteration of the loop
4065 and see if we have an available copy into SRC. */
4066 regno
= REGNO (src
);
4069 /* SET1 holds the last set that was available and anticipatable at
4074 /* Subroutine of cprop_insn that tries to propagate constants into
4075 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
4076 it is the instruction that immediately precedes JUMP, and must be a
4077 single SET of a register. FROM is what we will try to replace,
4078 SRC is the constant we will try to substitute for it. Returns nonzero
4079 if a change was made. */
4082 cprop_jump (bb
, setcc
, jump
, from
, src
)
4089 rtx
new, set_src
, note_src
;
4090 rtx set
= pc_set (jump
);
4091 rtx note
= find_reg_equal_equiv_note (jump
);
4095 note_src
= XEXP (note
, 0);
4096 if (GET_CODE (note_src
) == EXPR_LIST
)
4097 note_src
= NULL_RTX
;
4099 else note_src
= NULL_RTX
;
4101 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
4102 set_src
= note_src
? note_src
: SET_SRC (set
);
4104 /* First substitute the SETCC condition into the JUMP instruction,
4105 then substitute that given values into this expanded JUMP. */
4106 if (setcc
!= NULL_RTX
4107 && !modified_between_p (from
, setcc
, jump
)
4108 && !modified_between_p (src
, setcc
, jump
))
4111 rtx setcc_set
= single_set (setcc
);
4112 rtx setcc_note
= find_reg_equal_equiv_note (setcc
);
4113 setcc_src
= (setcc_note
&& GET_CODE (XEXP (setcc_note
, 0)) != EXPR_LIST
)
4114 ? XEXP (setcc_note
, 0) : SET_SRC (setcc_set
);
4115 set_src
= simplify_replace_rtx (set_src
, SET_DEST (setcc_set
),
4121 new = simplify_replace_rtx (set_src
, from
, src
);
4123 /* If no simplification can be made, then try the next register. */
4124 if (rtx_equal_p (new, SET_SRC (set
)))
4127 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
4132 /* Ensure the value computed inside the jump insn to be equivalent
4133 to one computed by setcc. */
4134 if (setcc
&& modified_in_p (new, setcc
))
4136 if (! validate_change (jump
, &SET_SRC (set
), new, 0))
4138 /* When (some) constants are not valid in a comparison, and there
4139 are two registers to be replaced by constants before the entire
4140 comparison can be folded into a constant, we need to keep
4141 intermediate information in REG_EQUAL notes. For targets with
4142 separate compare insns, such notes are added by try_replace_reg.
4143 When we have a combined compare-and-branch instruction, however,
4144 we need to attach a note to the branch itself to make this
4145 optimization work. */
4147 if (!rtx_equal_p (new, note_src
))
4148 set_unique_reg_note (jump
, REG_EQUAL
, copy_rtx (new));
4152 /* Remove REG_EQUAL note after simplification. */
4154 remove_note (jump
, note
);
4156 /* If this has turned into an unconditional jump,
4157 then put a barrier after it so that the unreachable
4158 code will be deleted. */
4159 if (GET_CODE (SET_SRC (set
)) == LABEL_REF
)
4160 emit_barrier_after (jump
);
4164 /* Delete the cc0 setter. */
4165 if (setcc
!= NULL
&& CC0_P (SET_DEST (single_set (setcc
))))
4166 delete_insn (setcc
);
4169 run_jump_opt_after_gcse
= 1;
4172 if (gcse_file
!= NULL
)
4175 "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
4176 REGNO (from
), INSN_UID (jump
));
4177 print_rtl (gcse_file
, src
);
4178 fprintf (gcse_file
, "\n");
4180 purge_dead_edges (bb
);
4186 constprop_register (insn
, from
, to
, alter_jumps
)
4194 /* Check for reg or cc0 setting instructions followed by
4195 conditional branch instructions first. */
4197 && (sset
= single_set (insn
)) != NULL
4199 && any_condjump_p (NEXT_INSN (insn
)) && onlyjump_p (NEXT_INSN (insn
)))
4201 rtx dest
= SET_DEST (sset
);
4202 if ((REG_P (dest
) || CC0_P (dest
))
4203 && cprop_jump (BLOCK_FOR_INSN (insn
), insn
, NEXT_INSN (insn
), from
, to
))
4207 /* Handle normal insns next. */
4208 if (GET_CODE (insn
) == INSN
4209 && try_replace_reg (from
, to
, insn
))
4212 /* Try to propagate a CONST_INT into a conditional jump.
4213 We're pretty specific about what we will handle in this
4214 code, we can extend this as necessary over time.
4216 Right now the insn in question must look like
4217 (set (pc) (if_then_else ...)) */
4218 else if (alter_jumps
&& any_condjump_p (insn
) && onlyjump_p (insn
))
4219 return cprop_jump (BLOCK_FOR_INSN (insn
), NULL
, insn
, from
, to
);
4223 /* Perform constant and copy propagation on INSN.
4224 The result is nonzero if a change was made. */
4227 cprop_insn (insn
, alter_jumps
)
4231 struct reg_use
*reg_used
;
4239 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4241 note
= find_reg_equal_equiv_note (insn
);
4243 /* We may win even when propagating constants into notes. */
4245 find_used_regs (&XEXP (note
, 0), NULL
);
4247 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
4248 reg_used
++, reg_use_count
--)
4250 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
4254 /* Ignore registers created by GCSE.
4255 We do this because ... */
4256 if (regno
>= max_gcse_regno
)
4259 /* If the register has already been set in this block, there's
4260 nothing we can do. */
4261 if (! oprs_not_set_p (reg_used
->reg_rtx
, insn
))
4264 /* Find an assignment that sets reg_used and is available
4265 at the start of the block. */
4266 set
= find_avail_set (regno
, insn
);
4271 /* ??? We might be able to handle PARALLELs. Later. */
4272 if (GET_CODE (pat
) != SET
)
4275 src
= SET_SRC (pat
);
4277 /* Constant propagation. */
4278 if (gcse_constant_p (src
))
4280 if (constprop_register (insn
, reg_used
->reg_rtx
, src
, alter_jumps
))
4284 if (gcse_file
!= NULL
)
4286 fprintf (gcse_file
, "GLOBAL CONST-PROP: Replacing reg %d in ", regno
);
4287 fprintf (gcse_file
, "insn %d with constant ", INSN_UID (insn
));
4288 print_rtl (gcse_file
, src
);
4289 fprintf (gcse_file
, "\n");
4291 if (INSN_DELETED_P (insn
))
4295 else if (GET_CODE (src
) == REG
4296 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
4297 && REGNO (src
) != regno
)
4299 if (try_replace_reg (reg_used
->reg_rtx
, src
, insn
))
4303 if (gcse_file
!= NULL
)
4305 fprintf (gcse_file
, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
4306 regno
, INSN_UID (insn
));
4307 fprintf (gcse_file
, " with reg %d\n", REGNO (src
));
4310 /* The original insn setting reg_used may or may not now be
4311 deletable. We leave the deletion to flow. */
4312 /* FIXME: If it turns out that the insn isn't deletable,
4313 then we may have unnecessarily extended register lifetimes
4314 and made things worse. */
4322 /* Like find_used_regs, but avoid recording uses that appear in
4323 input-output contexts such as zero_extract or pre_dec. This
4324 restricts the cases we consider to those for which local cprop
4325 can legitimately make replacements. */
4328 local_cprop_find_used_regs (xptr
, data
)
4337 switch (GET_CODE (x
))
4341 case STRICT_LOW_PART
:
4350 /* Can only legitimately appear this early in the context of
4351 stack pushes for function arguments, but handle all of the
4352 codes nonetheless. */
4356 /* Setting a subreg of a register larger than word_mode leaves
4357 the non-written words unchanged. */
4358 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x
))) > BITS_PER_WORD
)
4366 find_used_regs (xptr
, data
);
4369 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4370 their REG_EQUAL notes need updating. */
4373 do_local_cprop (x
, insn
, alter_jumps
, libcall_sp
)
4379 rtx newreg
= NULL
, newcnst
= NULL
;
4381 /* Rule out USE instructions and ASM statements as we don't want to
4382 change the hard registers mentioned. */
4383 if (GET_CODE (x
) == REG
4384 && (REGNO (x
) >= FIRST_PSEUDO_REGISTER
4385 || (GET_CODE (PATTERN (insn
)) != USE
4386 && asm_noperands (PATTERN (insn
)) < 0)))
4388 cselib_val
*val
= cselib_lookup (x
, GET_MODE (x
), 0);
4389 struct elt_loc_list
*l
;
4393 for (l
= val
->locs
; l
; l
= l
->next
)
4395 rtx this_rtx
= l
->loc
;
4401 if (gcse_constant_p (this_rtx
))
4403 if (REG_P (this_rtx
) && REGNO (this_rtx
) >= FIRST_PSEUDO_REGISTER
4404 /* Don't copy propagate if it has attached REG_EQUIV note.
4405 At this point this only function parameters should have
4406 REG_EQUIV notes and if the argument slot is used somewhere
4407 explicitly, it means address of parameter has been taken,
4408 so we should not extend the lifetime of the pseudo. */
4409 && (!(note
= find_reg_note (l
->setting_insn
, REG_EQUIV
, NULL_RTX
))
4410 || GET_CODE (XEXP (note
, 0)) != MEM
))
4413 if (newcnst
&& constprop_register (insn
, x
, newcnst
, alter_jumps
))
4415 /* If we find a case where we can't fix the retval REG_EQUAL notes
4416 match the new register, we either have to abandon this replacement
4417 or fix delete_trivially_dead_insns to preserve the setting insn,
4418 or make it delete the REG_EUAQL note, and fix up all passes that
4419 require the REG_EQUAL note there. */
4420 if (!adjust_libcall_notes (x
, newcnst
, insn
, libcall_sp
))
4422 if (gcse_file
!= NULL
)
4424 fprintf (gcse_file
, "LOCAL CONST-PROP: Replacing reg %d in ",
4426 fprintf (gcse_file
, "insn %d with constant ",
4428 print_rtl (gcse_file
, newcnst
);
4429 fprintf (gcse_file
, "\n");
4434 else if (newreg
&& newreg
!= x
&& try_replace_reg (x
, newreg
, insn
))
4436 adjust_libcall_notes (x
, newreg
, insn
, libcall_sp
);
4437 if (gcse_file
!= NULL
)
4440 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
4441 REGNO (x
), INSN_UID (insn
));
4442 fprintf (gcse_file
, " with reg %d\n", REGNO (newreg
));
4451 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4452 their REG_EQUAL notes need updating to reflect that OLDREG has been
4453 replaced with NEWVAL in INSN. Return true if all substitutions could
4456 adjust_libcall_notes (oldreg
, newval
, insn
, libcall_sp
)
4457 rtx oldreg
, newval
, insn
, *libcall_sp
;
4461 while ((end
= *libcall_sp
++))
4463 rtx note
= find_reg_equal_equiv_note (end
);
4470 if (reg_set_between_p (newval
, PREV_INSN (insn
), end
))
4474 note
= find_reg_equal_equiv_note (end
);
4477 if (reg_mentioned_p (newval
, XEXP (note
, 0)))
4480 while ((end
= *libcall_sp
++));
4484 XEXP (note
, 0) = replace_rtx (XEXP (note
, 0), oldreg
, newval
);
4490 #define MAX_NESTED_LIBCALLS 9
4493 local_cprop_pass (alter_jumps
)
4497 struct reg_use
*reg_used
;
4498 rtx libcall_stack
[MAX_NESTED_LIBCALLS
+ 1], *libcall_sp
;
4499 bool changed
= false;
4502 libcall_sp
= &libcall_stack
[MAX_NESTED_LIBCALLS
];
4504 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4508 rtx note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
4512 if (libcall_sp
== libcall_stack
)
4514 *--libcall_sp
= XEXP (note
, 0);
4516 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
4519 note
= find_reg_equal_equiv_note (insn
);
4523 note_uses (&PATTERN (insn
), local_cprop_find_used_regs
, NULL
);
4525 local_cprop_find_used_regs (&XEXP (note
, 0), NULL
);
4527 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
4528 reg_used
++, reg_use_count
--)
4529 if (do_local_cprop (reg_used
->reg_rtx
, insn
, alter_jumps
,
4535 if (INSN_DELETED_P (insn
))
4538 while (reg_use_count
);
4540 cselib_process_insn (insn
);
4543 /* Global analysis may get into infinite loops for unreachable blocks. */
4544 if (changed
&& alter_jumps
)
4546 delete_unreachable_blocks ();
4547 free_reg_set_mem ();
4548 alloc_reg_set_mem (max_reg_num ());
4549 compute_sets (get_insns ());
4553 /* Forward propagate copies. This includes copies and constants. Return
4554 nonzero if a change was made. */
4564 /* Note we start at block 1. */
4565 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
4567 if (gcse_file
!= NULL
)
4568 fprintf (gcse_file
, "\n");
4573 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
4575 /* Reset tables used to keep track of what's still valid [since the
4576 start of the block]. */
4577 reset_opr_set_tables ();
4579 for (insn
= bb
->head
;
4580 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
4581 insn
= NEXT_INSN (insn
))
4584 changed
|= cprop_insn (insn
, alter_jumps
);
4586 /* Keep track of everything modified by this insn. */
4587 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
4588 call mark_oprs_set if we turned the insn into a NOTE. */
4589 if (GET_CODE (insn
) != NOTE
)
4590 mark_oprs_set (insn
);
4594 if (gcse_file
!= NULL
)
4595 fprintf (gcse_file
, "\n");
4600 /* Similar to get_condition, only the resulting condition must be
4601 valid at JUMP, instead of at EARLIEST.
4603 This differs from noce_get_condition in ifcvt.c in that we prefer not to
4604 settle for the condition variable in the jump instruction being integral.
4605 We prefer to be able to record the value of a user variable, rather than
4606 the value of a temporary used in a condition. This could be solved by
4607 recording the value of *every* register scaned by canonicalize_condition,
4608 but this would require some code reorganization. */
4611 fis_get_condition (jump
)
4614 rtx cond
, set
, tmp
, insn
, earliest
;
4617 if (! any_condjump_p (jump
))
4620 set
= pc_set (jump
);
4621 cond
= XEXP (SET_SRC (set
), 0);
4623 /* If this branches to JUMP_LABEL when the condition is false,
4624 reverse the condition. */
4625 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
4626 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
4628 /* Use canonicalize_condition to do the dirty work of manipulating
4629 MODE_CC values and COMPARE rtx codes. */
4630 tmp
= canonicalize_condition (jump
, cond
, reverse
, &earliest
, NULL_RTX
);
4634 /* Verify that the given condition is valid at JUMP by virtue of not
4635 having been modified since EARLIEST. */
4636 for (insn
= earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
4637 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
4642 /* The condition was modified. See if we can get a partial result
4643 that doesn't follow all the reversals. Perhaps combine can fold
4644 them together later. */
4645 tmp
= XEXP (tmp
, 0);
4646 if (!REG_P (tmp
) || GET_MODE_CLASS (GET_MODE (tmp
)) != MODE_INT
)
4648 tmp
= canonicalize_condition (jump
, cond
, reverse
, &earliest
, tmp
);
4652 /* For sanity's sake, re-validate the new result. */
4653 for (insn
= earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
4654 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
4660 /* Find the implicit sets of a function. An "implicit set" is a constraint
4661 on the value of a variable, implied by a conditional jump. For example,
4662 following "if (x == 2)", the then branch may be optimized as though the
4663 conditional performed an "explicit set", in this example, "x = 2". This
4664 function records the set patterns that are implicit at the start of each
4668 find_implicit_sets ()
4670 basic_block bb
, dest
;
4676 /* Check for more than one sucessor. */
4677 if (bb
->succ
&& bb
->succ
->succ_next
)
4679 cond
= fis_get_condition (bb
->end
);
4682 && (GET_CODE (cond
) == EQ
|| GET_CODE (cond
) == NE
)
4683 && GET_CODE (XEXP (cond
, 0)) == REG
4684 && REGNO (XEXP (cond
, 0)) >= FIRST_PSEUDO_REGISTER
4685 && gcse_constant_p (XEXP (cond
, 1)))
4687 dest
= GET_CODE (cond
) == EQ
? BRANCH_EDGE (bb
)->dest
4688 : FALLTHRU_EDGE (bb
)->dest
;
4690 if (dest
&& ! dest
->pred
->pred_next
4691 && dest
!= EXIT_BLOCK_PTR
)
4693 new = gen_rtx_SET (VOIDmode
, XEXP (cond
, 0),
4695 implicit_sets
[dest
->index
] = new;
4698 fprintf(gcse_file
, "Implicit set of reg %d in ",
4699 REGNO (XEXP (cond
, 0)));
4700 fprintf(gcse_file
, "basic block %d\n", dest
->index
);
4708 fprintf (gcse_file
, "Found %d implicit sets\n", count
);
4711 /* Perform one copy/constant propagation pass.
4712 PASS is the pass count. If CPROP_JUMPS is true, perform constant
4713 propagation into conditional jumps. If BYPASS_JUMPS is true,
4714 perform conditional jump bypassing optimizations. */
4717 one_cprop_pass (pass
, cprop_jumps
, bypass_jumps
)
4724 const_prop_count
= 0;
4725 copy_prop_count
= 0;
4727 local_cprop_pass (cprop_jumps
);
4729 /* Determine implicit sets. */
4730 implicit_sets
= (rtx
*) xcalloc (last_basic_block
, sizeof (rtx
));
4731 find_implicit_sets ();
4733 alloc_hash_table (max_cuid
, &set_hash_table
, 1);
4734 compute_hash_table (&set_hash_table
);
4736 /* Free implicit_sets before peak usage. */
4737 free (implicit_sets
);
4738 implicit_sets
= NULL
;
4741 dump_hash_table (gcse_file
, "SET", &set_hash_table
);
4742 if (set_hash_table
.n_elems
> 0)
4744 alloc_cprop_mem (last_basic_block
, set_hash_table
.n_elems
);
4745 compute_cprop_data ();
4746 changed
= cprop (cprop_jumps
);
4748 changed
|= bypass_conditional_jumps ();
4752 free_hash_table (&set_hash_table
);
4756 fprintf (gcse_file
, "CPROP of %s, pass %d: %d bytes needed, ",
4757 current_function_name
, pass
, bytes_used
);
4758 fprintf (gcse_file
, "%d const props, %d copy props\n\n",
4759 const_prop_count
, copy_prop_count
);
4761 /* Global analysis may get into infinite loops for unreachable blocks. */
4762 if (changed
&& cprop_jumps
)
4763 delete_unreachable_blocks ();
4768 /* Bypass conditional jumps. */
4770 /* The value of last_basic_block at the beginning of the jump_bypass
4771 pass. The use of redirect_edge_and_branch_force may introduce new
4772 basic blocks, but the data flow analysis is only valid for basic
4773 block indices less than bypass_last_basic_block. */
4775 static int bypass_last_basic_block
;
4777 /* Find a set of REGNO to a constant that is available at the end of basic
4778 block BB. Returns NULL if no such set is found. Based heavily upon
4781 static struct expr
*
4782 find_bypass_set (regno
, bb
)
4786 struct expr
*result
= 0;
4791 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
4795 if (TEST_BIT (cprop_avout
[bb
], set
->bitmap_index
))
4797 set
= next_set (regno
, set
);
4803 if (GET_CODE (set
->expr
) != SET
)
4806 src
= SET_SRC (set
->expr
);
4807 if (gcse_constant_p (src
))
4810 if (GET_CODE (src
) != REG
)
4813 regno
= REGNO (src
);
4819 /* Subroutine of bypass_block that checks whether a pseudo is killed by
4820 any of the instructions inserted on an edge. Jump bypassing places
4821 condition code setters on CFG edges using insert_insn_on_edge. This
4822 function is required to check that our data flow analysis is still
4823 valid prior to commit_edge_insertions. */
4826 reg_killed_on_edge (reg
, e
)
4832 for (insn
= e
->insns
; insn
; insn
= NEXT_INSN (insn
))
4833 if (INSN_P (insn
) && reg_set_p (reg
, insn
))
4839 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
4840 basic block BB which has more than one predecessor. If not NULL, SETCC
4841 is the first instruction of BB, which is immediately followed by JUMP_INSN
4842 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
4843 Returns nonzero if a change was made.
4845 During the jump bypassing pass, we may place copies of SETCC instructions
4846 on CFG edges. The following routine must be careful to pay attention to
4847 these inserted insns when performing its transformations. */
4850 bypass_block (bb
, setcc
, jump
)
4855 edge e
, enext
, edest
;
4857 int may_be_loop_header
;
4859 insn
= (setcc
!= NULL
) ? setcc
: jump
;
4861 /* Determine set of register uses in INSN. */
4863 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4864 note
= find_reg_equal_equiv_note (insn
);
4866 find_used_regs (&XEXP (note
, 0), NULL
);
4868 may_be_loop_header
= false;
4869 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
4870 if (e
->flags
& EDGE_DFS_BACK
)
4872 may_be_loop_header
= true;
4877 for (e
= bb
->pred
; e
; e
= enext
)
4879 enext
= e
->pred_next
;
4880 if (e
->flags
& EDGE_COMPLEX
)
4883 /* We can't redirect edges from new basic blocks. */
4884 if (e
->src
->index
>= bypass_last_basic_block
)
4887 /* The irreducible loops created by redirecting of edges entering the
4888 loop from outside would decrease effectiveness of some of the following
4889 optimizations, so prevent this. */
4890 if (may_be_loop_header
4891 && !(e
->flags
& EDGE_DFS_BACK
))
4894 for (i
= 0; i
< reg_use_count
; i
++)
4896 struct reg_use
*reg_used
= ®_use_table
[i
];
4897 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
4898 basic_block dest
, old_dest
;
4902 if (regno
>= max_gcse_regno
)
4905 set
= find_bypass_set (regno
, e
->src
->index
);
4910 /* Check the data flow is valid after edge insertions. */
4911 if (e
->insns
&& reg_killed_on_edge (reg_used
->reg_rtx
, e
))
4914 src
= SET_SRC (pc_set (jump
));
4917 src
= simplify_replace_rtx (src
,
4918 SET_DEST (PATTERN (setcc
)),
4919 SET_SRC (PATTERN (setcc
)));
4921 new = simplify_replace_rtx (src
, reg_used
->reg_rtx
,
4922 SET_SRC (set
->expr
));
4924 /* Jump bypassing may have already placed instructions on
4925 edges of the CFG. We can't bypass an outgoing edge that
4926 has instructions associated with it, as these insns won't
4927 get executed if the incoming edge is redirected. */
4931 edest
= FALLTHRU_EDGE (bb
);
4932 dest
= edest
->insns
? NULL
: edest
->dest
;
4934 else if (GET_CODE (new) == LABEL_REF
)
4936 dest
= BLOCK_FOR_INSN (XEXP (new, 0));
4937 /* Don't bypass edges containing instructions. */
4938 for (edest
= bb
->succ
; edest
; edest
= edest
->succ_next
)
4939 if (edest
->dest
== dest
&& edest
->insns
)
4951 && dest
!= EXIT_BLOCK_PTR
)
4953 redirect_edge_and_branch_force (e
, dest
);
4955 /* Copy the register setter to the redirected edge.
4956 Don't copy CC0 setters, as CC0 is dead after jump. */
4959 rtx pat
= PATTERN (setcc
);
4960 if (!CC0_P (SET_DEST (pat
)))
4961 insert_insn_on_edge (copy_insn (pat
), e
);
4964 if (gcse_file
!= NULL
)
4966 fprintf (gcse_file
, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
4967 regno
, INSN_UID (jump
));
4968 print_rtl (gcse_file
, SET_SRC (set
->expr
));
4969 fprintf (gcse_file
, "\nBypass edge from %d->%d to %d\n",
4970 e
->src
->index
, old_dest
->index
, dest
->index
);
4980 /* Find basic blocks with more than one predecessor that only contain a
4981 single conditional jump. If the result of the comparison is known at
4982 compile-time from any incoming edge, redirect that edge to the
4983 appropriate target. Returns nonzero if a change was made.
4985 This function is now mis-named, because we also handle indirect jumps. */
4988 bypass_conditional_jumps ()
4996 /* Note we start at block 1. */
4997 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
5000 bypass_last_basic_block
= last_basic_block
;
5001 mark_dfs_back_edges ();
5004 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
,
5005 EXIT_BLOCK_PTR
, next_bb
)
5007 /* Check for more than one predecessor. */
5008 if (bb
->pred
&& bb
->pred
->pred_next
)
5011 for (insn
= bb
->head
;
5012 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
5013 insn
= NEXT_INSN (insn
))
5014 if (GET_CODE (insn
) == INSN
)
5018 if (GET_CODE (PATTERN (insn
)) != SET
)
5021 dest
= SET_DEST (PATTERN (insn
));
5022 if (REG_P (dest
) || CC0_P (dest
))
5027 else if (GET_CODE (insn
) == JUMP_INSN
)
5029 if ((any_condjump_p (insn
) || computed_jump_p (insn
))
5030 && onlyjump_p (insn
))
5031 changed
|= bypass_block (bb
, setcc
, insn
);
5034 else if (INSN_P (insn
))
5039 /* If we bypassed any register setting insns, we inserted a
5040 copy on the redirected edge. These need to be committed. */
5042 commit_edge_insertions();
5047 /* Compute PRE+LCM working variables. */
5049 /* Local properties of expressions. */
5050 /* Nonzero for expressions that are transparent in the block. */
5051 static sbitmap
*transp
;
5053 /* Nonzero for expressions that are transparent at the end of the block.
5054 This is only zero for expressions killed by abnormal critical edge
5055 created by a calls. */
5056 static sbitmap
*transpout
;
5058 /* Nonzero for expressions that are computed (available) in the block. */
5059 static sbitmap
*comp
;
5061 /* Nonzero for expressions that are locally anticipatable in the block. */
5062 static sbitmap
*antloc
;
5064 /* Nonzero for expressions where this block is an optimal computation
5066 static sbitmap
*pre_optimal
;
5068 /* Nonzero for expressions which are redundant in a particular block. */
5069 static sbitmap
*pre_redundant
;
5071 /* Nonzero for expressions which should be inserted on a specific edge. */
5072 static sbitmap
*pre_insert_map
;
5074 /* Nonzero for expressions which should be deleted in a specific block. */
5075 static sbitmap
*pre_delete_map
;
5077 /* Contains the edge_list returned by pre_edge_lcm. */
5078 static struct edge_list
*edge_list
;
5080 /* Redundant insns. */
5081 static sbitmap pre_redundant_insns
;
5083 /* Allocate vars used for PRE analysis. */
5086 alloc_pre_mem (n_blocks
, n_exprs
)
5087 int n_blocks
, n_exprs
;
5089 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5090 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5091 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5094 pre_redundant
= NULL
;
5095 pre_insert_map
= NULL
;
5096 pre_delete_map
= NULL
;
5099 ae_kill
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5101 /* pre_insert and pre_delete are allocated later. */
5104 /* Free vars used for PRE analysis. */
5109 sbitmap_vector_free (transp
);
5110 sbitmap_vector_free (comp
);
5112 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
5115 sbitmap_vector_free (pre_optimal
);
5117 sbitmap_vector_free (pre_redundant
);
5119 sbitmap_vector_free (pre_insert_map
);
5121 sbitmap_vector_free (pre_delete_map
);
5123 sbitmap_vector_free (ae_in
);
5125 sbitmap_vector_free (ae_out
);
5127 transp
= comp
= NULL
;
5128 pre_optimal
= pre_redundant
= pre_insert_map
= pre_delete_map
= NULL
;
5129 ae_in
= ae_out
= NULL
;
5132 /* Top level routine to do the dataflow analysis needed by PRE. */
5137 sbitmap trapping_expr
;
5141 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
5142 sbitmap_vector_zero (ae_kill
, last_basic_block
);
5144 /* Collect expressions which might trap. */
5145 trapping_expr
= sbitmap_alloc (expr_hash_table
.n_elems
);
5146 sbitmap_zero (trapping_expr
);
5147 for (ui
= 0; ui
< expr_hash_table
.size
; ui
++)
5150 for (e
= expr_hash_table
.table
[ui
]; e
!= NULL
; e
= e
->next_same_hash
)
5151 if (may_trap_p (e
->expr
))
5152 SET_BIT (trapping_expr
, e
->bitmap_index
);
5155 /* Compute ae_kill for each basic block using:
5159 This is significantly faster than compute_ae_kill. */
5165 /* If the current block is the destination of an abnormal edge, we
5166 kill all trapping expressions because we won't be able to properly
5167 place the instruction on the edge. So make them neither
5168 anticipatable nor transparent. This is fairly conservative. */
5169 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
5170 if (e
->flags
& EDGE_ABNORMAL
)
5172 sbitmap_difference (antloc
[bb
->index
], antloc
[bb
->index
], trapping_expr
);
5173 sbitmap_difference (transp
[bb
->index
], transp
[bb
->index
], trapping_expr
);
5177 sbitmap_a_or_b (ae_kill
[bb
->index
], transp
[bb
->index
], comp
[bb
->index
]);
5178 sbitmap_not (ae_kill
[bb
->index
], ae_kill
[bb
->index
]);
5181 edge_list
= pre_edge_lcm (gcse_file
, expr_hash_table
.n_elems
, transp
, comp
, antloc
,
5182 ae_kill
, &pre_insert_map
, &pre_delete_map
);
5183 sbitmap_vector_free (antloc
);
5185 sbitmap_vector_free (ae_kill
);
5187 sbitmap_free (trapping_expr
);
5192 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
5195 VISITED is a pointer to a working buffer for tracking which BB's have
5196 been visited. It is NULL for the top-level call.
5198 We treat reaching expressions that go through blocks containing the same
5199 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
5200 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
5201 2 as not reaching. The intent is to improve the probability of finding
5202 only one reaching expression and to reduce register lifetimes by picking
5203 the closest such expression. */
5206 pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
)
5207 basic_block occr_bb
;
5214 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
5216 basic_block pred_bb
= pred
->src
;
5218 if (pred
->src
== ENTRY_BLOCK_PTR
5219 /* Has predecessor has already been visited? */
5220 || visited
[pred_bb
->index
])
5221 ;/* Nothing to do. */
5223 /* Does this predecessor generate this expression? */
5224 else if (TEST_BIT (comp
[pred_bb
->index
], expr
->bitmap_index
))
5226 /* Is this the occurrence we're looking for?
5227 Note that there's only one generating occurrence per block
5228 so we just need to check the block number. */
5229 if (occr_bb
== pred_bb
)
5232 visited
[pred_bb
->index
] = 1;
5234 /* Ignore this predecessor if it kills the expression. */
5235 else if (! TEST_BIT (transp
[pred_bb
->index
], expr
->bitmap_index
))
5236 visited
[pred_bb
->index
] = 1;
5238 /* Neither gen nor kill. */
5241 visited
[pred_bb
->index
] = 1;
5242 if (pre_expr_reaches_here_p_work (occr_bb
, expr
, pred_bb
, visited
))
5247 /* All paths have been checked. */
5251 /* The wrapper for pre_expr_reaches_here_work that ensures that any
5252 memory allocated for that function is returned. */
5255 pre_expr_reaches_here_p (occr_bb
, expr
, bb
)
5256 basic_block occr_bb
;
5261 char *visited
= (char *) xcalloc (last_basic_block
, 1);
5263 rval
= pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
);
5270 /* Given an expr, generate RTL which we can insert at the end of a BB,
5271 or on an edge. Set the block number of any insns generated to
5275 process_insert_insn (expr
)
5278 rtx reg
= expr
->reaching_reg
;
5279 rtx exp
= copy_rtx (expr
->expr
);
5284 /* If the expression is something that's an operand, like a constant,
5285 just copy it to a register. */
5286 if (general_operand (exp
, GET_MODE (reg
)))
5287 emit_move_insn (reg
, exp
);
5289 /* Otherwise, make a new insn to compute this expression and make sure the
5290 insn will be recognized (this also adds any needed CLOBBERs). Copy the
5291 expression to make sure we don't have any sharing issues. */
5292 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode
, reg
, exp
))))
5301 /* Add EXPR to the end of basic block BB.
5303 This is used by both the PRE and code hoisting.
5305 For PRE, we want to verify that the expr is either transparent
5306 or locally anticipatable in the target block. This check makes
5307 no sense for code hoisting. */
5310 insert_insn_end_bb (expr
, bb
, pre
)
5317 rtx reg
= expr
->reaching_reg
;
5318 int regno
= REGNO (reg
);
5321 pat
= process_insert_insn (expr
);
5322 if (pat
== NULL_RTX
|| ! INSN_P (pat
))
5326 while (NEXT_INSN (pat_end
) != NULL_RTX
)
5327 pat_end
= NEXT_INSN (pat_end
);
5329 /* If the last insn is a jump, insert EXPR in front [taking care to
5330 handle cc0, etc. properly]. Similary we need to care trapping
5331 instructions in presence of non-call exceptions. */
5333 if (GET_CODE (insn
) == JUMP_INSN
5334 || (GET_CODE (insn
) == INSN
5335 && (bb
->succ
->succ_next
|| (bb
->succ
->flags
& EDGE_ABNORMAL
))))
5340 /* It should always be the case that we can put these instructions
5341 anywhere in the basic block with performing PRE optimizations.
5343 if (GET_CODE (insn
) == INSN
&& pre
5344 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
5345 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
5348 /* If this is a jump table, then we can't insert stuff here. Since
5349 we know the previous real insn must be the tablejump, we insert
5350 the new instruction just before the tablejump. */
5351 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
5352 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
5353 insn
= prev_real_insn (insn
);
5356 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
5357 if cc0 isn't set. */
5358 note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
5360 insn
= XEXP (note
, 0);
5363 rtx maybe_cc0_setter
= prev_nonnote_insn (insn
);
5364 if (maybe_cc0_setter
5365 && INSN_P (maybe_cc0_setter
)
5366 && sets_cc0_p (PATTERN (maybe_cc0_setter
)))
5367 insn
= maybe_cc0_setter
;
5370 /* FIXME: What if something in cc0/jump uses value set in new insn? */
5371 new_insn
= emit_insn_before (pat
, insn
);
5374 /* Likewise if the last insn is a call, as will happen in the presence
5375 of exception handling. */
5376 else if (GET_CODE (insn
) == CALL_INSN
5377 && (bb
->succ
->succ_next
|| (bb
->succ
->flags
& EDGE_ABNORMAL
)))
5379 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
5380 we search backward and place the instructions before the first
5381 parameter is loaded. Do this for everyone for consistency and a
5382 presumption that we'll get better code elsewhere as well.
5384 It should always be the case that we can put these instructions
5385 anywhere in the basic block with performing PRE optimizations.
5389 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
5390 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
5393 /* Since different machines initialize their parameter registers
5394 in different orders, assume nothing. Collect the set of all
5395 parameter registers. */
5396 insn
= find_first_parameter_load (insn
, bb
->head
);
5398 /* If we found all the parameter loads, then we want to insert
5399 before the first parameter load.
5401 If we did not find all the parameter loads, then we might have
5402 stopped on the head of the block, which could be a CODE_LABEL.
5403 If we inserted before the CODE_LABEL, then we would be putting
5404 the insn in the wrong basic block. In that case, put the insn
5405 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
5406 while (GET_CODE (insn
) == CODE_LABEL
5407 || NOTE_INSN_BASIC_BLOCK_P (insn
))
5408 insn
= NEXT_INSN (insn
);
5410 new_insn
= emit_insn_before (pat
, insn
);
5413 new_insn
= emit_insn_after (pat
, insn
);
5419 add_label_notes (PATTERN (pat
), new_insn
);
5420 note_stores (PATTERN (pat
), record_set_info
, pat
);
5424 pat
= NEXT_INSN (pat
);
5427 gcse_create_count
++;
5431 fprintf (gcse_file
, "PRE/HOIST: end of bb %d, insn %d, ",
5432 bb
->index
, INSN_UID (new_insn
));
5433 fprintf (gcse_file
, "copying expression %d to reg %d\n",
5434 expr
->bitmap_index
, regno
);
5438 /* Insert partially redundant expressions on edges in the CFG to make
5439 the expressions fully redundant. */
5442 pre_edge_insert (edge_list
, index_map
)
5443 struct edge_list
*edge_list
;
5444 struct expr
**index_map
;
5446 int e
, i
, j
, num_edges
, set_size
, did_insert
= 0;
5449 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
5450 if it reaches any of the deleted expressions. */
5452 set_size
= pre_insert_map
[0]->size
;
5453 num_edges
= NUM_EDGES (edge_list
);
5454 inserted
= sbitmap_vector_alloc (num_edges
, expr_hash_table
.n_elems
);
5455 sbitmap_vector_zero (inserted
, num_edges
);
5457 for (e
= 0; e
< num_edges
; e
++)
5460 basic_block bb
= INDEX_EDGE_PRED_BB (edge_list
, e
);
5462 for (i
= indx
= 0; i
< set_size
; i
++, indx
+= SBITMAP_ELT_BITS
)
5464 SBITMAP_ELT_TYPE insert
= pre_insert_map
[e
]->elms
[i
];
5466 for (j
= indx
; insert
&& j
< (int) expr_hash_table
.n_elems
; j
++, insert
>>= 1)
5467 if ((insert
& 1) != 0 && index_map
[j
]->reaching_reg
!= NULL_RTX
)
5469 struct expr
*expr
= index_map
[j
];
5472 /* Now look at each deleted occurrence of this expression. */
5473 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5475 if (! occr
->deleted_p
)
5478 /* Insert this expression on this edge if if it would
5479 reach the deleted occurrence in BB. */
5480 if (!TEST_BIT (inserted
[e
], j
))
5483 edge eg
= INDEX_EDGE (edge_list
, e
);
5485 /* We can't insert anything on an abnormal and
5486 critical edge, so we insert the insn at the end of
5487 the previous block. There are several alternatives
5488 detailed in Morgans book P277 (sec 10.5) for
5489 handling this situation. This one is easiest for
5492 if ((eg
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
5493 insert_insn_end_bb (index_map
[j
], bb
, 0);
5496 insn
= process_insert_insn (index_map
[j
]);
5497 insert_insn_on_edge (insn
, eg
);
5502 fprintf (gcse_file
, "PRE/HOIST: edge (%d,%d), ",
5504 INDEX_EDGE_SUCC_BB (edge_list
, e
)->index
);
5505 fprintf (gcse_file
, "copy expression %d\n",
5506 expr
->bitmap_index
);
5509 update_ld_motion_stores (expr
);
5510 SET_BIT (inserted
[e
], j
);
5512 gcse_create_count
++;
5519 sbitmap_vector_free (inserted
);
5523 /* Copy the result of INSN to REG. INDX is the expression number. */
5526 pre_insert_copy_insn (expr
, insn
)
5530 rtx reg
= expr
->reaching_reg
;
5531 int regno
= REGNO (reg
);
5532 int indx
= expr
->bitmap_index
;
5533 rtx set
= single_set (insn
);
5539 new_insn
= emit_insn_after (gen_move_insn (reg
, copy_rtx (SET_DEST (set
))), insn
);
5541 /* Keep register set table up to date. */
5542 record_one_set (regno
, new_insn
);
5544 gcse_create_count
++;
5548 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
5549 BLOCK_NUM (insn
), INSN_UID (new_insn
), indx
,
5550 INSN_UID (insn
), regno
);
5551 update_ld_motion_stores (expr
);
5554 /* Copy available expressions that reach the redundant expression
5555 to `reaching_reg'. */
5558 pre_insert_copies ()
5565 /* For each available expression in the table, copy the result to
5566 `reaching_reg' if the expression reaches a deleted one.
5568 ??? The current algorithm is rather brute force.
5569 Need to do some profiling. */
5571 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5572 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5574 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
5575 we don't want to insert a copy here because the expression may not
5576 really be redundant. So only insert an insn if the expression was
5577 deleted. This test also avoids further processing if the
5578 expression wasn't deleted anywhere. */
5579 if (expr
->reaching_reg
== NULL
)
5582 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5584 if (! occr
->deleted_p
)
5587 for (avail
= expr
->avail_occr
; avail
!= NULL
; avail
= avail
->next
)
5589 rtx insn
= avail
->insn
;
5591 /* No need to handle this one if handled already. */
5592 if (avail
->copied_p
)
5595 /* Don't handle this one if it's a redundant one. */
5596 if (TEST_BIT (pre_redundant_insns
, INSN_CUID (insn
)))
5599 /* Or if the expression doesn't reach the deleted one. */
5600 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail
->insn
),
5602 BLOCK_FOR_INSN (occr
->insn
)))
5605 /* Copy the result of avail to reaching_reg. */
5606 pre_insert_copy_insn (expr
, insn
);
5607 avail
->copied_p
= 1;
5613 /* Emit move from SRC to DEST noting the equivalence with expression computed
5616 gcse_emit_move_after (src
, dest
, insn
)
5617 rtx src
, dest
, insn
;
5620 rtx set
= single_set (insn
), set2
;
5624 /* This should never fail since we're creating a reg->reg copy
5625 we've verified to be valid. */
5627 new = emit_insn_after (gen_move_insn (dest
, src
), insn
);
5629 /* Note the equivalence for local CSE pass. */
5630 set2
= single_set (new);
5631 if (!set2
|| !rtx_equal_p (SET_DEST (set2
), dest
))
5633 if ((note
= find_reg_equal_equiv_note (insn
)))
5634 eqv
= XEXP (note
, 0);
5636 eqv
= SET_SRC (set
);
5638 set_unique_reg_note (new, REG_EQUAL
, copy_insn_1 (eqv
));
5643 /* Delete redundant computations.
5644 Deletion is done by changing the insn to copy the `reaching_reg' of
5645 the expression into the result of the SET. It is left to later passes
5646 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
5648 Returns nonzero if a change is made. */
5659 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5660 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5662 int indx
= expr
->bitmap_index
;
5664 /* We only need to search antic_occr since we require
5667 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5669 rtx insn
= occr
->insn
;
5671 basic_block bb
= BLOCK_FOR_INSN (insn
);
5673 if (TEST_BIT (pre_delete_map
[bb
->index
], indx
))
5675 set
= single_set (insn
);
5679 /* Create a pseudo-reg to store the result of reaching
5680 expressions into. Get the mode for the new pseudo from
5681 the mode of the original destination pseudo. */
5682 if (expr
->reaching_reg
== NULL
)
5684 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
5686 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
5688 occr
->deleted_p
= 1;
5689 SET_BIT (pre_redundant_insns
, INSN_CUID (insn
));
5696 "PRE: redundant insn %d (expression %d) in ",
5697 INSN_UID (insn
), indx
);
5698 fprintf (gcse_file
, "bb %d, reaching reg is %d\n",
5699 bb
->index
, REGNO (expr
->reaching_reg
));
5708 /* Perform GCSE optimizations using PRE.
5709 This is called by one_pre_gcse_pass after all the dataflow analysis
5712 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
5713 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
5714 Compiler Design and Implementation.
5716 ??? A new pseudo reg is created to hold the reaching expression. The nice
5717 thing about the classical approach is that it would try to use an existing
5718 reg. If the register can't be adequately optimized [i.e. we introduce
5719 reload problems], one could add a pass here to propagate the new register
5722 ??? We don't handle single sets in PARALLELs because we're [currently] not
5723 able to copy the rest of the parallel when we insert copies to create full
5724 redundancies from partial redundancies. However, there's no reason why we
5725 can't handle PARALLELs in the cases where there are no partial
5732 int did_insert
, changed
;
5733 struct expr
**index_map
;
5736 /* Compute a mapping from expression number (`bitmap_index') to
5737 hash table entry. */
5739 index_map
= (struct expr
**) xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
5740 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5741 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5742 index_map
[expr
->bitmap_index
] = expr
;
5744 /* Reset bitmap used to track which insns are redundant. */
5745 pre_redundant_insns
= sbitmap_alloc (max_cuid
);
5746 sbitmap_zero (pre_redundant_insns
);
5748 /* Delete the redundant insns first so that
5749 - we know what register to use for the new insns and for the other
5750 ones with reaching expressions
5751 - we know which insns are redundant when we go to create copies */
5753 changed
= pre_delete ();
5755 did_insert
= pre_edge_insert (edge_list
, index_map
);
5757 /* In other places with reaching expressions, copy the expression to the
5758 specially allocated pseudo-reg that reaches the redundant expr. */
5759 pre_insert_copies ();
5762 commit_edge_insertions ();
5767 sbitmap_free (pre_redundant_insns
);
5771 /* Top level routine to perform one PRE GCSE pass.
5773 Return nonzero if a change was made. */
5776 one_pre_gcse_pass (pass
)
5781 gcse_subst_count
= 0;
5782 gcse_create_count
= 0;
5784 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
5785 add_noreturn_fake_exit_edges ();
5787 compute_ld_motion_mems ();
5789 compute_hash_table (&expr_hash_table
);
5790 trim_ld_motion_mems ();
5792 dump_hash_table (gcse_file
, "Expression", &expr_hash_table
);
5794 if (expr_hash_table
.n_elems
> 0)
5796 alloc_pre_mem (last_basic_block
, expr_hash_table
.n_elems
);
5797 compute_pre_data ();
5798 changed
|= pre_gcse ();
5799 free_edge_list (edge_list
);
5804 remove_fake_edges ();
5805 free_hash_table (&expr_hash_table
);
5809 fprintf (gcse_file
, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
5810 current_function_name
, pass
, bytes_used
);
5811 fprintf (gcse_file
, "%d substs, %d insns created\n",
5812 gcse_subst_count
, gcse_create_count
);
5818 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
5819 If notes are added to an insn which references a CODE_LABEL, the
5820 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
5821 because the following loop optimization pass requires them. */
5823 /* ??? This is very similar to the loop.c add_label_notes function. We
5824 could probably share code here. */
5826 /* ??? If there was a jump optimization pass after gcse and before loop,
5827 then we would not need to do this here, because jump would add the
5828 necessary REG_LABEL notes. */
5831 add_label_notes (x
, insn
)
5835 enum rtx_code code
= GET_CODE (x
);
5839 if (code
== LABEL_REF
&& !LABEL_REF_NONLOCAL_P (x
))
5841 /* This code used to ignore labels that referred to dispatch tables to
5842 avoid flow generating (slightly) worse code.
5844 We no longer ignore such label references (see LABEL_REF handling in
5845 mark_jump_label for additional information). */
5847 REG_NOTES (insn
) = gen_rtx_INSN_LIST (REG_LABEL
, XEXP (x
, 0),
5849 if (LABEL_P (XEXP (x
, 0)))
5850 LABEL_NUSES (XEXP (x
, 0))++;
5854 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
5857 add_label_notes (XEXP (x
, i
), insn
);
5858 else if (fmt
[i
] == 'E')
5859 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5860 add_label_notes (XVECEXP (x
, i
, j
), insn
);
5864 /* Compute transparent outgoing information for each block.
5866 An expression is transparent to an edge unless it is killed by
5867 the edge itself. This can only happen with abnormal control flow,
5868 when the edge is traversed through a call. This happens with
5869 non-local labels and exceptions.
5871 This would not be necessary if we split the edge. While this is
5872 normally impossible for abnormal critical edges, with some effort
5873 it should be possible with exception handling, since we still have
5874 control over which handler should be invoked. But due to increased
5875 EH table sizes, this may not be worthwhile. */
5878 compute_transpout ()
5884 sbitmap_vector_ones (transpout
, last_basic_block
);
5888 /* Note that flow inserted a nop a the end of basic blocks that
5889 end in call instructions for reasons other than abnormal
5891 if (GET_CODE (bb
->end
) != CALL_INSN
)
5894 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5895 for (expr
= expr_hash_table
.table
[i
]; expr
; expr
= expr
->next_same_hash
)
5896 if (GET_CODE (expr
->expr
) == MEM
)
5898 if (GET_CODE (XEXP (expr
->expr
, 0)) == SYMBOL_REF
5899 && CONSTANT_POOL_ADDRESS_P (XEXP (expr
->expr
, 0)))
5902 /* ??? Optimally, we would use interprocedural alias
5903 analysis to determine if this mem is actually killed
5905 RESET_BIT (transpout
[bb
->index
], expr
->bitmap_index
);
5910 /* Removal of useless null pointer checks */
5912 /* Called via note_stores. X is set by SETTER. If X is a register we must
5913 invalidate nonnull_local and set nonnull_killed. DATA is really a
5914 `null_pointer_info *'.
5916 We ignore hard registers. */
5919 invalidate_nonnull_info (x
, setter
, data
)
5921 rtx setter ATTRIBUTE_UNUSED
;
5925 struct null_pointer_info
*npi
= (struct null_pointer_info
*) data
;
5927 while (GET_CODE (x
) == SUBREG
)
5930 /* Ignore anything that is not a register or is a hard register. */
5931 if (GET_CODE (x
) != REG
5932 || REGNO (x
) < npi
->min_reg
5933 || REGNO (x
) >= npi
->max_reg
)
5936 regno
= REGNO (x
) - npi
->min_reg
;
5938 RESET_BIT (npi
->nonnull_local
[npi
->current_block
->index
], regno
);
5939 SET_BIT (npi
->nonnull_killed
[npi
->current_block
->index
], regno
);
5942 /* Do null-pointer check elimination for the registers indicated in
5943 NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
5944 they are not our responsibility to free. */
5947 delete_null_pointer_checks_1 (block_reg
, nonnull_avin
,
5949 unsigned int *block_reg
;
5950 sbitmap
*nonnull_avin
;
5951 sbitmap
*nonnull_avout
;
5952 struct null_pointer_info
*npi
;
5954 basic_block bb
, current_block
;
5955 sbitmap
*nonnull_local
= npi
->nonnull_local
;
5956 sbitmap
*nonnull_killed
= npi
->nonnull_killed
;
5957 int something_changed
= 0;
5959 /* Compute local properties, nonnull and killed. A register will have
5960 the nonnull property if at the end of the current block its value is
5961 known to be nonnull. The killed property indicates that somewhere in
5962 the block any information we had about the register is killed.
5964 Note that a register can have both properties in a single block. That
5965 indicates that it's killed, then later in the block a new value is
5967 sbitmap_vector_zero (nonnull_local
, last_basic_block
);
5968 sbitmap_vector_zero (nonnull_killed
, last_basic_block
);
5970 FOR_EACH_BB (current_block
)
5972 rtx insn
, stop_insn
;
5974 /* Set the current block for invalidate_nonnull_info. */
5975 npi
->current_block
= current_block
;
5977 /* Scan each insn in the basic block looking for memory references and
5979 stop_insn
= NEXT_INSN (current_block
->end
);
5980 for (insn
= current_block
->head
;
5982 insn
= NEXT_INSN (insn
))
5987 /* Ignore anything that is not a normal insn. */
5988 if (! INSN_P (insn
))
5991 /* Basically ignore anything that is not a simple SET. We do have
5992 to make sure to invalidate nonnull_local and set nonnull_killed
5993 for such insns though. */
5994 set
= single_set (insn
);
5997 note_stores (PATTERN (insn
), invalidate_nonnull_info
, npi
);
6001 /* See if we've got a usable memory load. We handle it first
6002 in case it uses its address register as a dest (which kills
6003 the nonnull property). */
6004 if (GET_CODE (SET_SRC (set
)) == MEM
6005 && GET_CODE ((reg
= XEXP (SET_SRC (set
), 0))) == REG
6006 && REGNO (reg
) >= npi
->min_reg
6007 && REGNO (reg
) < npi
->max_reg
)
6008 SET_BIT (nonnull_local
[current_block
->index
],
6009 REGNO (reg
) - npi
->min_reg
);
6011 /* Now invalidate stuff clobbered by this insn. */
6012 note_stores (PATTERN (insn
), invalidate_nonnull_info
, npi
);
6014 /* And handle stores, we do these last since any sets in INSN can
6015 not kill the nonnull property if it is derived from a MEM
6016 appearing in a SET_DEST. */
6017 if (GET_CODE (SET_DEST (set
)) == MEM
6018 && GET_CODE ((reg
= XEXP (SET_DEST (set
), 0))) == REG
6019 && REGNO (reg
) >= npi
->min_reg
6020 && REGNO (reg
) < npi
->max_reg
)
6021 SET_BIT (nonnull_local
[current_block
->index
],
6022 REGNO (reg
) - npi
->min_reg
);
6026 /* Now compute global properties based on the local properties. This
6027 is a classic global availability algorithm. */
6028 compute_available (nonnull_local
, nonnull_killed
,
6029 nonnull_avout
, nonnull_avin
);
6031 /* Now look at each bb and see if it ends with a compare of a value
6035 rtx last_insn
= bb
->end
;
6036 rtx condition
, earliest
;
6037 int compare_and_branch
;
6039 /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
6040 since BLOCK_REG[BB] is zero if this block did not end with a
6041 comparison against zero, this condition works. */
6042 if (block_reg
[bb
->index
] < npi
->min_reg
6043 || block_reg
[bb
->index
] >= npi
->max_reg
)
6046 /* LAST_INSN is a conditional jump. Get its condition. */
6047 condition
= get_condition (last_insn
, &earliest
);
6049 /* If we can't determine the condition then skip. */
6053 /* Is the register known to have a nonzero value? */
6054 if (!TEST_BIT (nonnull_avout
[bb
->index
], block_reg
[bb
->index
] - npi
->min_reg
))
6057 /* Try to compute whether the compare/branch at the loop end is one or
6058 two instructions. */
6059 if (earliest
== last_insn
)
6060 compare_and_branch
= 1;
6061 else if (earliest
== prev_nonnote_insn (last_insn
))
6062 compare_and_branch
= 2;
6066 /* We know the register in this comparison is nonnull at exit from
6067 this block. We can optimize this comparison. */
6068 if (GET_CODE (condition
) == NE
)
6072 new_jump
= emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn
)),
6074 JUMP_LABEL (new_jump
) = JUMP_LABEL (last_insn
);
6075 LABEL_NUSES (JUMP_LABEL (new_jump
))++;
6076 emit_barrier_after (new_jump
);
6079 something_changed
= 1;
6080 delete_insn (last_insn
);
6081 if (compare_and_branch
== 2)
6082 delete_insn (earliest
);
6083 purge_dead_edges (bb
);
6085 /* Don't check this block again. (Note that BLOCK_END is
6086 invalid here; we deleted the last instruction in the
6088 block_reg
[bb
->index
] = 0;
6091 return something_changed
;
6094 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
6097 This is conceptually similar to global constant/copy propagation and
6098 classic global CSE (it even uses the same dataflow equations as cprop).
6100 If a register is used as memory address with the form (mem (reg)), then we
6101 know that REG can not be zero at that point in the program. Any instruction
6102 which sets REG "kills" this property.
6104 So, if every path leading to a conditional branch has an available memory
6105 reference of that form, then we know the register can not have the value
6106 zero at the conditional branch.
6108 So we merely need to compute the local properties and propagate that data
6109 around the cfg, then optimize where possible.
6111 We run this pass two times. Once before CSE, then again after CSE. This
6112 has proven to be the most profitable approach. It is rare for new
6113 optimization opportunities of this nature to appear after the first CSE
6116 This could probably be integrated with global cprop with a little work. */
6119 delete_null_pointer_checks (f
)
6120 rtx f ATTRIBUTE_UNUSED
;
6122 sbitmap
*nonnull_avin
, *nonnull_avout
;
6123 unsigned int *block_reg
;
6128 struct null_pointer_info npi
;
6129 int something_changed
= 0;
6131 /* If we have only a single block, then there's nothing to do. */
6132 if (n_basic_blocks
<= 1)
6135 /* Trying to perform global optimizations on flow graphs which have
6136 a high connectivity will take a long time and is unlikely to be
6137 particularly useful.
6139 In normal circumstances a cfg should have about twice as many edges
6140 as blocks. But we do not want to punish small functions which have
6141 a couple switch statements. So we require a relatively large number
6142 of basic blocks and the ratio of edges to blocks to be high. */
6143 if (n_basic_blocks
> 1000 && n_edges
/ n_basic_blocks
>= 20)
6146 /* We need four bitmaps, each with a bit for each register in each
6148 max_reg
= max_reg_num ();
6149 regs_per_pass
= get_bitmap_width (4, last_basic_block
, max_reg
);
6151 /* Allocate bitmaps to hold local and global properties. */
6152 npi
.nonnull_local
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6153 npi
.nonnull_killed
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6154 nonnull_avin
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6155 nonnull_avout
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6157 /* Go through the basic blocks, seeing whether or not each block
6158 ends with a conditional branch whose condition is a comparison
6159 against zero. Record the register compared in BLOCK_REG. */
6160 block_reg
= (unsigned int *) xcalloc (last_basic_block
, sizeof (int));
6163 rtx last_insn
= bb
->end
;
6164 rtx condition
, earliest
, reg
;
6166 /* We only want conditional branches. */
6167 if (GET_CODE (last_insn
) != JUMP_INSN
6168 || !any_condjump_p (last_insn
)
6169 || !onlyjump_p (last_insn
))
6172 /* LAST_INSN is a conditional jump. Get its condition. */
6173 condition
= get_condition (last_insn
, &earliest
);
6175 /* If we were unable to get the condition, or it is not an equality
6176 comparison against zero then there's nothing we can do. */
6178 || (GET_CODE (condition
) != NE
&& GET_CODE (condition
) != EQ
)
6179 || GET_CODE (XEXP (condition
, 1)) != CONST_INT
6180 || (XEXP (condition
, 1)
6181 != CONST0_RTX (GET_MODE (XEXP (condition
, 0)))))
6184 /* We must be checking a register against zero. */
6185 reg
= XEXP (condition
, 0);
6186 if (GET_CODE (reg
) != REG
)
6189 block_reg
[bb
->index
] = REGNO (reg
);
6192 /* Go through the algorithm for each block of registers. */
6193 for (reg
= FIRST_PSEUDO_REGISTER
; reg
< max_reg
; reg
+= regs_per_pass
)
6196 npi
.max_reg
= MIN (reg
+ regs_per_pass
, max_reg
);
6197 something_changed
|= delete_null_pointer_checks_1 (block_reg
,
6203 /* Free the table of registers compared at the end of every block. */
6207 sbitmap_vector_free (npi
.nonnull_local
);
6208 sbitmap_vector_free (npi
.nonnull_killed
);
6209 sbitmap_vector_free (nonnull_avin
);
6210 sbitmap_vector_free (nonnull_avout
);
6212 return something_changed
;
6215 /* Code Hoisting variables and subroutines. */
6217 /* Very busy expressions. */
6218 static sbitmap
*hoist_vbein
;
6219 static sbitmap
*hoist_vbeout
;
6221 /* Hoistable expressions. */
6222 static sbitmap
*hoist_exprs
;
6224 /* Dominator bitmaps. */
6225 dominance_info dominators
;
6227 /* ??? We could compute post dominators and run this algorithm in
6228 reverse to perform tail merging, doing so would probably be
6229 more effective than the tail merging code in jump.c.
6231 It's unclear if tail merging could be run in parallel with
6232 code hoisting. It would be nice. */
6234 /* Allocate vars used for code hoisting analysis. */
6237 alloc_code_hoist_mem (n_blocks
, n_exprs
)
6238 int n_blocks
, n_exprs
;
6240 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6241 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6242 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6244 hoist_vbein
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6245 hoist_vbeout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6246 hoist_exprs
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6247 transpout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6250 /* Free vars used for code hoisting analysis. */
6253 free_code_hoist_mem ()
6255 sbitmap_vector_free (antloc
);
6256 sbitmap_vector_free (transp
);
6257 sbitmap_vector_free (comp
);
6259 sbitmap_vector_free (hoist_vbein
);
6260 sbitmap_vector_free (hoist_vbeout
);
6261 sbitmap_vector_free (hoist_exprs
);
6262 sbitmap_vector_free (transpout
);
6264 free_dominance_info (dominators
);
6267 /* Compute the very busy expressions at entry/exit from each block.
6269 An expression is very busy if all paths from a given point
6270 compute the expression. */
6273 compute_code_hoist_vbeinout ()
6275 int changed
, passes
;
6278 sbitmap_vector_zero (hoist_vbeout
, last_basic_block
);
6279 sbitmap_vector_zero (hoist_vbein
, last_basic_block
);
6288 /* We scan the blocks in the reverse order to speed up
6290 FOR_EACH_BB_REVERSE (bb
)
6292 changed
|= sbitmap_a_or_b_and_c_cg (hoist_vbein
[bb
->index
], antloc
[bb
->index
],
6293 hoist_vbeout
[bb
->index
], transp
[bb
->index
]);
6294 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
6295 sbitmap_intersection_of_succs (hoist_vbeout
[bb
->index
], hoist_vbein
, bb
->index
);
6302 fprintf (gcse_file
, "hoisting vbeinout computation: %d passes\n", passes
);
6305 /* Top level routine to do the dataflow analysis needed by code hoisting. */
6308 compute_code_hoist_data ()
6310 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
6311 compute_transpout ();
6312 compute_code_hoist_vbeinout ();
6313 dominators
= calculate_dominance_info (CDI_DOMINATORS
);
6315 fprintf (gcse_file
, "\n");
6318 /* Determine if the expression identified by EXPR_INDEX would
6319 reach BB unimpared if it was placed at the end of EXPR_BB.
6321 It's unclear exactly what Muchnick meant by "unimpared". It seems
6322 to me that the expression must either be computed or transparent in
6323 *every* block in the path(s) from EXPR_BB to BB. Any other definition
6324 would allow the expression to be hoisted out of loops, even if
6325 the expression wasn't a loop invariant.
6327 Contrast this to reachability for PRE where an expression is
6328 considered reachable if *any* path reaches instead of *all*
6332 hoist_expr_reaches_here_p (expr_bb
, expr_index
, bb
, visited
)
6333 basic_block expr_bb
;
6339 int visited_allocated_locally
= 0;
6342 if (visited
== NULL
)
6344 visited_allocated_locally
= 1;
6345 visited
= xcalloc (last_basic_block
, 1);
6348 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
6350 basic_block pred_bb
= pred
->src
;
6352 if (pred
->src
== ENTRY_BLOCK_PTR
)
6354 else if (pred_bb
== expr_bb
)
6356 else if (visited
[pred_bb
->index
])
6359 /* Does this predecessor generate this expression? */
6360 else if (TEST_BIT (comp
[pred_bb
->index
], expr_index
))
6362 else if (! TEST_BIT (transp
[pred_bb
->index
], expr_index
))
6368 visited
[pred_bb
->index
] = 1;
6369 if (! hoist_expr_reaches_here_p (expr_bb
, expr_index
,
6374 if (visited_allocated_locally
)
6377 return (pred
== NULL
);
6380 /* Actually perform code hoisting. */
6385 basic_block bb
, dominated
;
6387 unsigned int domby_len
;
6389 struct expr
**index_map
;
6392 sbitmap_vector_zero (hoist_exprs
, last_basic_block
);
6394 /* Compute a mapping from expression number (`bitmap_index') to
6395 hash table entry. */
6397 index_map
= (struct expr
**) xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
6398 for (i
= 0; i
< expr_hash_table
.size
; i
++)
6399 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
6400 index_map
[expr
->bitmap_index
] = expr
;
6402 /* Walk over each basic block looking for potentially hoistable
6403 expressions, nothing gets hoisted from the entry block. */
6407 int insn_inserted_p
;
6409 domby_len
= get_dominated_by (dominators
, bb
, &domby
);
6410 /* Examine each expression that is very busy at the exit of this
6411 block. These are the potentially hoistable expressions. */
6412 for (i
= 0; i
< hoist_vbeout
[bb
->index
]->n_bits
; i
++)
6416 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
)
6417 && TEST_BIT (transpout
[bb
->index
], i
))
6419 /* We've found a potentially hoistable expression, now
6420 we look at every block BB dominates to see if it
6421 computes the expression. */
6422 for (j
= 0; j
< domby_len
; j
++)
6424 dominated
= domby
[j
];
6425 /* Ignore self dominance. */
6426 if (bb
== dominated
)
6428 /* We've found a dominated block, now see if it computes
6429 the busy expression and whether or not moving that
6430 expression to the "beginning" of that block is safe. */
6431 if (!TEST_BIT (antloc
[dominated
->index
], i
))
6434 /* Note if the expression would reach the dominated block
6435 unimpared if it was placed at the end of BB.
6437 Keep track of how many times this expression is hoistable
6438 from a dominated block into BB. */
6439 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
6443 /* If we found more than one hoistable occurrence of this
6444 expression, then note it in the bitmap of expressions to
6445 hoist. It makes no sense to hoist things which are computed
6446 in only one BB, and doing so tends to pessimize register
6447 allocation. One could increase this value to try harder
6448 to avoid any possible code expansion due to register
6449 allocation issues; however experiments have shown that
6450 the vast majority of hoistable expressions are only movable
6451 from two successors, so raising this threshold is likely
6452 to nullify any benefit we get from code hoisting. */
6455 SET_BIT (hoist_exprs
[bb
->index
], i
);
6460 /* If we found nothing to hoist, then quit now. */
6467 /* Loop over all the hoistable expressions. */
6468 for (i
= 0; i
< hoist_exprs
[bb
->index
]->n_bits
; i
++)
6470 /* We want to insert the expression into BB only once, so
6471 note when we've inserted it. */
6472 insn_inserted_p
= 0;
6474 /* These tests should be the same as the tests above. */
6475 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
))
6477 /* We've found a potentially hoistable expression, now
6478 we look at every block BB dominates to see if it
6479 computes the expression. */
6480 for (j
= 0; j
< domby_len
; j
++)
6482 dominated
= domby
[j
];
6483 /* Ignore self dominance. */
6484 if (bb
== dominated
)
6487 /* We've found a dominated block, now see if it computes
6488 the busy expression and whether or not moving that
6489 expression to the "beginning" of that block is safe. */
6490 if (!TEST_BIT (antloc
[dominated
->index
], i
))
6493 /* The expression is computed in the dominated block and
6494 it would be safe to compute it at the start of the
6495 dominated block. Now we have to determine if the
6496 expression would reach the dominated block if it was
6497 placed at the end of BB. */
6498 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
6500 struct expr
*expr
= index_map
[i
];
6501 struct occr
*occr
= expr
->antic_occr
;
6505 /* Find the right occurrence of this expression. */
6506 while (BLOCK_FOR_INSN (occr
->insn
) != dominated
&& occr
)
6509 /* Should never happen. */
6515 set
= single_set (insn
);
6519 /* Create a pseudo-reg to store the result of reaching
6520 expressions into. Get the mode for the new pseudo
6521 from the mode of the original destination pseudo. */
6522 if (expr
->reaching_reg
== NULL
)
6524 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
6526 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
6528 occr
->deleted_p
= 1;
6529 if (!insn_inserted_p
)
6531 insert_insn_end_bb (index_map
[i
], bb
, 0);
6532 insn_inserted_p
= 1;
6544 /* Top level routine to perform one code hoisting (aka unification) pass
6546 Return nonzero if a change was made. */
6549 one_code_hoisting_pass ()
6553 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
6554 compute_hash_table (&expr_hash_table
);
6556 dump_hash_table (gcse_file
, "Code Hosting Expressions", &expr_hash_table
);
6558 if (expr_hash_table
.n_elems
> 0)
6560 alloc_code_hoist_mem (last_basic_block
, expr_hash_table
.n_elems
);
6561 compute_code_hoist_data ();
6563 free_code_hoist_mem ();
6566 free_hash_table (&expr_hash_table
);
6571 /* Here we provide the things required to do store motion towards
6572 the exit. In order for this to be effective, gcse also needed to
6573 be taught how to move a load when it is kill only by a store to itself.
6578 void foo(float scale)
6580 for (i=0; i<10; i++)
6584 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
6585 the load out since its live around the loop, and stored at the bottom
6588 The 'Load Motion' referred to and implemented in this file is
6589 an enhancement to gcse which when using edge based lcm, recognizes
6590 this situation and allows gcse to move the load out of the loop.
6592 Once gcse has hoisted the load, store motion can then push this
6593 load towards the exit, and we end up with no loads or stores of 'i'
6596 /* This will search the ldst list for a matching expression. If it
6597 doesn't find one, we create one and initialize it. */
6599 static struct ls_expr
*
6603 struct ls_expr
* ptr
;
6605 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6606 if (expr_equiv_p (ptr
->pattern
, x
))
6611 ptr
= (struct ls_expr
*) xmalloc (sizeof (struct ls_expr
));
6613 ptr
->next
= pre_ldst_mems
;
6616 ptr
->pattern_regs
= NULL_RTX
;
6617 ptr
->loads
= NULL_RTX
;
6618 ptr
->stores
= NULL_RTX
;
6619 ptr
->reaching_reg
= NULL_RTX
;
6622 ptr
->hash_index
= 0;
6623 pre_ldst_mems
= ptr
;
6629 /* Free up an individual ldst entry. */
6632 free_ldst_entry (ptr
)
6633 struct ls_expr
* ptr
;
6635 free_INSN_LIST_list (& ptr
->loads
);
6636 free_INSN_LIST_list (& ptr
->stores
);
6641 /* Free up all memory associated with the ldst list. */
6646 while (pre_ldst_mems
)
6648 struct ls_expr
* tmp
= pre_ldst_mems
;
6650 pre_ldst_mems
= pre_ldst_mems
->next
;
6652 free_ldst_entry (tmp
);
6655 pre_ldst_mems
= NULL
;
6658 /* Dump debugging info about the ldst list. */
6661 print_ldst_list (file
)
6664 struct ls_expr
* ptr
;
6666 fprintf (file
, "LDST list: \n");
6668 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6670 fprintf (file
, " Pattern (%3d): ", ptr
->index
);
6672 print_rtl (file
, ptr
->pattern
);
6674 fprintf (file
, "\n Loads : ");
6677 print_rtl (file
, ptr
->loads
);
6679 fprintf (file
, "(nil)");
6681 fprintf (file
, "\n Stores : ");
6684 print_rtl (file
, ptr
->stores
);
6686 fprintf (file
, "(nil)");
6688 fprintf (file
, "\n\n");
6691 fprintf (file
, "\n");
6694 /* Returns 1 if X is in the list of ldst only expressions. */
6696 static struct ls_expr
*
6697 find_rtx_in_ldst (x
)
6700 struct ls_expr
* ptr
;
6702 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
6703 if (expr_equiv_p (ptr
->pattern
, x
) && ! ptr
->invalid
)
6709 /* Assign each element of the list of mems a monotonically increasing value. */
6714 struct ls_expr
* ptr
;
6717 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
6723 /* Return first item in the list. */
6725 static inline struct ls_expr
*
6728 return pre_ldst_mems
;
6731 /* Return the next item in the list after the specified one. */
6733 static inline struct ls_expr
*
6735 struct ls_expr
* ptr
;
6740 /* Load Motion for loads which only kill themselves. */
6742 /* Return true if x is a simple MEM operation, with no registers or
6743 side effects. These are the types of loads we consider for the
6744 ld_motion list, otherwise we let the usual aliasing take care of it. */
6750 if (GET_CODE (x
) != MEM
)
6753 if (MEM_VOLATILE_P (x
))
6756 if (GET_MODE (x
) == BLKmode
)
6759 /* If we are handling exceptions, we must be careful with memory references
6760 that may trap. If we are not, the behavior is undefined, so we may just
6762 if (flag_non_call_exceptions
&& may_trap_p (x
))
6765 if (side_effects_p (x
))
6768 /* Do not consider function arguments passed on stack. */
6769 if (reg_mentioned_p (stack_pointer_rtx
, x
))
6772 if (flag_float_store
&& FLOAT_MODE_P (GET_MODE (x
)))
6778 /* Make sure there isn't a buried reference in this pattern anywhere.
6779 If there is, invalidate the entry for it since we're not capable
6780 of fixing it up just yet.. We have to be sure we know about ALL
6781 loads since the aliasing code will allow all entries in the
6782 ld_motion list to not-alias itself. If we miss a load, we will get
6783 the wrong value since gcse might common it and we won't know to
6787 invalidate_any_buried_refs (x
)
6792 struct ls_expr
* ptr
;
6794 /* Invalidate it in the list. */
6795 if (GET_CODE (x
) == MEM
&& simple_mem (x
))
6797 ptr
= ldst_entry (x
);
6801 /* Recursively process the insn. */
6802 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
6804 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0; i
--)
6807 invalidate_any_buried_refs (XEXP (x
, i
));
6808 else if (fmt
[i
] == 'E')
6809 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
6810 invalidate_any_buried_refs (XVECEXP (x
, i
, j
));
6814 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
6815 being defined as MEM loads and stores to symbols, with no side effects
6816 and no registers in the expression. For a MEM destination, we also
6817 check that the insn is still valid if we replace the destination with a
6818 REG, as is done in update_ld_motion_stores. If there are any uses/defs
6819 which don't match this criteria, they are invalidated and trimmed out
6823 compute_ld_motion_mems ()
6825 struct ls_expr
* ptr
;
6829 pre_ldst_mems
= NULL
;
6833 for (insn
= bb
->head
;
6834 insn
&& insn
!= NEXT_INSN (bb
->end
);
6835 insn
= NEXT_INSN (insn
))
6839 if (GET_CODE (PATTERN (insn
)) == SET
)
6841 rtx src
= SET_SRC (PATTERN (insn
));
6842 rtx dest
= SET_DEST (PATTERN (insn
));
6844 /* Check for a simple LOAD... */
6845 if (GET_CODE (src
) == MEM
&& simple_mem (src
))
6847 ptr
= ldst_entry (src
);
6848 if (GET_CODE (dest
) == REG
)
6849 ptr
->loads
= alloc_INSN_LIST (insn
, ptr
->loads
);
6855 /* Make sure there isn't a buried load somewhere. */
6856 invalidate_any_buried_refs (src
);
6859 /* Check for stores. Don't worry about aliased ones, they
6860 will block any movement we might do later. We only care
6861 about this exact pattern since those are the only
6862 circumstance that we will ignore the aliasing info. */
6863 if (GET_CODE (dest
) == MEM
&& simple_mem (dest
))
6865 ptr
= ldst_entry (dest
);
6867 if (GET_CODE (src
) != MEM
6868 && GET_CODE (src
) != ASM_OPERANDS
6869 /* Check for REG manually since want_to_gcse_p
6870 returns 0 for all REGs. */
6871 && (REG_P (src
) || want_to_gcse_p (src
)))
6872 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
6878 invalidate_any_buried_refs (PATTERN (insn
));
6884 /* Remove any references that have been either invalidated or are not in the
6885 expression list for pre gcse. */
6888 trim_ld_motion_mems ()
6890 struct ls_expr
* last
= NULL
;
6891 struct ls_expr
* ptr
= first_ls_expr ();
6895 int del
= ptr
->invalid
;
6896 struct expr
* expr
= NULL
;
6898 /* Delete if entry has been made invalid. */
6904 /* Delete if we cannot find this mem in the expression list. */
6905 for (i
= 0; i
< expr_hash_table
.size
&& del
; i
++)
6907 for (expr
= expr_hash_table
.table
[i
];
6909 expr
= expr
->next_same_hash
)
6910 if (expr_equiv_p (expr
->expr
, ptr
->pattern
))
6922 last
->next
= ptr
->next
;
6923 free_ldst_entry (ptr
);
6928 pre_ldst_mems
= pre_ldst_mems
->next
;
6929 free_ldst_entry (ptr
);
6930 ptr
= pre_ldst_mems
;
6935 /* Set the expression field if we are keeping it. */
6942 /* Show the world what we've found. */
6943 if (gcse_file
&& pre_ldst_mems
!= NULL
)
6944 print_ldst_list (gcse_file
);
6947 /* This routine will take an expression which we are replacing with
6948 a reaching register, and update any stores that are needed if
6949 that expression is in the ld_motion list. Stores are updated by
6950 copying their SRC to the reaching register, and then storeing
6951 the reaching register into the store location. These keeps the
6952 correct value in the reaching register for the loads. */
6955 update_ld_motion_stores (expr
)
6958 struct ls_expr
* mem_ptr
;
6960 if ((mem_ptr
= find_rtx_in_ldst (expr
->expr
)))
6962 /* We can try to find just the REACHED stores, but is shouldn't
6963 matter to set the reaching reg everywhere... some might be
6964 dead and should be eliminated later. */
6966 /* We replace (set mem expr) with (set reg expr) (set mem reg)
6967 where reg is the reaching reg used in the load. We checked in
6968 compute_ld_motion_mems that we can replace (set mem expr) with
6969 (set reg expr) in that insn. */
6970 rtx list
= mem_ptr
->stores
;
6972 for ( ; list
!= NULL_RTX
; list
= XEXP (list
, 1))
6974 rtx insn
= XEXP (list
, 0);
6975 rtx pat
= PATTERN (insn
);
6976 rtx src
= SET_SRC (pat
);
6977 rtx reg
= expr
->reaching_reg
;
6980 /* If we've already copied it, continue. */
6981 if (expr
->reaching_reg
== src
)
6986 fprintf (gcse_file
, "PRE: store updated with reaching reg ");
6987 print_rtl (gcse_file
, expr
->reaching_reg
);
6988 fprintf (gcse_file
, ":\n ");
6989 print_inline_rtx (gcse_file
, insn
, 8);
6990 fprintf (gcse_file
, "\n");
6993 copy
= gen_move_insn ( reg
, copy_rtx (SET_SRC (pat
)));
6994 new = emit_insn_before (copy
, insn
);
6995 record_one_set (REGNO (reg
), new);
6996 SET_SRC (pat
) = reg
;
6998 /* un-recognize this pattern since it's probably different now. */
6999 INSN_CODE (insn
) = -1;
7000 gcse_create_count
++;
7005 /* Store motion code. */
7007 #define ANTIC_STORE_LIST(x) ((x)->loads)
7008 #define AVAIL_STORE_LIST(x) ((x)->stores)
7009 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
7011 /* This is used to communicate the target bitvector we want to use in the
7012 reg_set_info routine when called via the note_stores mechanism. */
7013 static int * regvec
;
7015 /* And current insn, for the same routine. */
7016 static rtx compute_store_table_current_insn
;
7018 /* Used in computing the reverse edge graph bit vectors. */
7019 static sbitmap
* st_antloc
;
7021 /* Global holding the number of store expressions we are dealing with. */
7022 static int num_stores
;
7024 /* Checks to set if we need to mark a register set. Called from note_stores. */
7027 reg_set_info (dest
, setter
, data
)
7028 rtx dest
, setter ATTRIBUTE_UNUSED
;
7029 void * data ATTRIBUTE_UNUSED
;
7031 if (GET_CODE (dest
) == SUBREG
)
7032 dest
= SUBREG_REG (dest
);
7034 if (GET_CODE (dest
) == REG
)
7035 regvec
[REGNO (dest
)] = INSN_UID (compute_store_table_current_insn
);
7038 /* Return zero if some of the registers in list X are killed
7039 due to set of registers in bitmap REGS_SET. */
7042 store_ops_ok (x
, regs_set
)
7048 for (; x
; x
= XEXP (x
, 1))
7051 if (regs_set
[REGNO(reg
)])
7058 /* Returns a list of registers mentioned in X. */
7060 extract_mentioned_regs (x
)
7063 return extract_mentioned_regs_helper (x
, NULL_RTX
);
7066 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
7069 extract_mentioned_regs_helper (x
, accum
)
7077 /* Repeat is used to turn tail-recursion into iteration. */
7083 code
= GET_CODE (x
);
7087 return alloc_EXPR_LIST (0, x
, accum
);
7097 /* We do not run this function with arguments having side effects. */
7116 i
= GET_RTX_LENGTH (code
) - 1;
7117 fmt
= GET_RTX_FORMAT (code
);
7123 rtx tem
= XEXP (x
, i
);
7125 /* If we are about to do the last recursive call
7126 needed at this level, change it into iteration. */
7133 accum
= extract_mentioned_regs_helper (tem
, accum
);
7135 else if (fmt
[i
] == 'E')
7139 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
7140 accum
= extract_mentioned_regs_helper (XVECEXP (x
, i
, j
), accum
);
7147 /* Determine whether INSN is MEM store pattern that we will consider moving.
7148 REGS_SET_BEFORE is bitmap of registers set before (and including) the
7149 current insn, REGS_SET_AFTER is bitmap of registers set after (and
7150 including) the insn in this basic block. We must be passing through BB from
7151 head to end, as we are using this fact to speed things up.
7153 The results are stored this way:
7155 -- the first anticipatable expression is added into ANTIC_STORE_LIST
7156 -- if the processed expression is not anticipatable, NULL_RTX is added
7157 there instead, so that we can use it as indicator that no further
7158 expression of this type may be anticipatable
7159 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
7160 consequently, all of them but this head are dead and may be deleted.
7161 -- if the expression is not available, the insn due to that it fails to be
7162 available is stored in reaching_reg.
7164 The things are complicated a bit by fact that there already may be stores
7165 to the same MEM from other blocks; also caller must take care of the
7166 necessary cleanup of the temporary markers after end of the basic block.
7170 find_moveable_store (insn
, regs_set_before
, regs_set_after
)
7172 int *regs_set_before
;
7173 int *regs_set_after
;
7175 struct ls_expr
* ptr
;
7177 int check_anticipatable
, check_available
;
7178 basic_block bb
= BLOCK_FOR_INSN (insn
);
7180 set
= single_set (insn
);
7184 dest
= SET_DEST (set
);
7186 if (GET_CODE (dest
) != MEM
|| MEM_VOLATILE_P (dest
)
7187 || GET_MODE (dest
) == BLKmode
)
7190 if (side_effects_p (dest
))
7193 /* If we are handling exceptions, we must be careful with memory references
7194 that may trap. If we are not, the behavior is undefined, so we may just
7196 if (flag_non_call_exceptions
&& may_trap_p (dest
))
7199 ptr
= ldst_entry (dest
);
7200 if (!ptr
->pattern_regs
)
7201 ptr
->pattern_regs
= extract_mentioned_regs (dest
);
7203 /* Do not check for anticipatability if we either found one anticipatable
7204 store already, or tested for one and found out that it was killed. */
7205 check_anticipatable
= 0;
7206 if (!ANTIC_STORE_LIST (ptr
))
7207 check_anticipatable
= 1;
7210 tmp
= XEXP (ANTIC_STORE_LIST (ptr
), 0);
7212 && BLOCK_FOR_INSN (tmp
) != bb
)
7213 check_anticipatable
= 1;
7215 if (check_anticipatable
)
7217 if (store_killed_before (dest
, ptr
->pattern_regs
, insn
, bb
, regs_set_before
))
7221 ANTIC_STORE_LIST (ptr
) = alloc_INSN_LIST (tmp
,
7222 ANTIC_STORE_LIST (ptr
));
7225 /* It is not necessary to check whether store is available if we did
7226 it successfully before; if we failed before, do not bother to check
7227 until we reach the insn that caused us to fail. */
7228 check_available
= 0;
7229 if (!AVAIL_STORE_LIST (ptr
))
7230 check_available
= 1;
7233 tmp
= XEXP (AVAIL_STORE_LIST (ptr
), 0);
7234 if (BLOCK_FOR_INSN (tmp
) != bb
)
7235 check_available
= 1;
7237 if (check_available
)
7239 /* Check that we have already reached the insn at that the check
7240 failed last time. */
7241 if (LAST_AVAIL_CHECK_FAILURE (ptr
))
7244 tmp
!= insn
&& tmp
!= LAST_AVAIL_CHECK_FAILURE (ptr
);
7245 tmp
= PREV_INSN (tmp
))
7248 check_available
= 0;
7251 check_available
= store_killed_after (dest
, ptr
->pattern_regs
, insn
,
7253 &LAST_AVAIL_CHECK_FAILURE (ptr
));
7255 if (!check_available
)
7256 AVAIL_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
, AVAIL_STORE_LIST (ptr
));
7259 /* Find available and anticipatable stores. */
7262 compute_store_table ()
7268 int *last_set_in
, *already_set
;
7269 struct ls_expr
* ptr
, **prev_next_ptr_ptr
;
7271 max_gcse_regno
= max_reg_num ();
7273 reg_set_in_block
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
,
7275 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
7277 last_set_in
= xmalloc (sizeof (int) * max_gcse_regno
);
7278 already_set
= xmalloc (sizeof (int) * max_gcse_regno
);
7280 /* Find all the stores we care about. */
7283 /* First compute the registers set in this block. */
7284 memset (last_set_in
, 0, sizeof (int) * max_gcse_regno
);
7285 regvec
= last_set_in
;
7287 for (insn
= bb
->head
;
7288 insn
!= NEXT_INSN (bb
->end
);
7289 insn
= NEXT_INSN (insn
))
7291 if (! INSN_P (insn
))
7294 if (GET_CODE (insn
) == CALL_INSN
)
7296 bool clobbers_all
= false;
7297 #ifdef NON_SAVING_SETJMP
7298 if (NON_SAVING_SETJMP
7299 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
7300 clobbers_all
= true;
7303 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
7305 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
7306 last_set_in
[regno
] = INSN_UID (insn
);
7309 pat
= PATTERN (insn
);
7310 compute_store_table_current_insn
= insn
;
7311 note_stores (pat
, reg_set_info
, NULL
);
7314 /* Record the set registers. */
7315 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
7316 if (last_set_in
[regno
])
7317 SET_BIT (reg_set_in_block
[bb
->index
], regno
);
7319 /* Now find the stores. */
7320 memset (already_set
, 0, sizeof (int) * max_gcse_regno
);
7321 regvec
= already_set
;
7322 for (insn
= bb
->head
;
7323 insn
!= NEXT_INSN (bb
->end
);
7324 insn
= NEXT_INSN (insn
))
7326 if (! INSN_P (insn
))
7329 if (GET_CODE (insn
) == CALL_INSN
)
7331 bool clobbers_all
= false;
7332 #ifdef NON_SAVING_SETJMP
7333 if (NON_SAVING_SETJMP
7334 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
7335 clobbers_all
= true;
7338 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
7340 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
7341 already_set
[regno
] = 1;
7344 pat
= PATTERN (insn
);
7345 note_stores (pat
, reg_set_info
, NULL
);
7347 /* Now that we've marked regs, look for stores. */
7348 find_moveable_store (insn
, already_set
, last_set_in
);
7350 /* Unmark regs that are no longer set. */
7351 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
7352 if (last_set_in
[regno
] == INSN_UID (insn
))
7353 last_set_in
[regno
] = 0;
7356 /* Clear temporary marks. */
7357 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7359 LAST_AVAIL_CHECK_FAILURE(ptr
) = NULL_RTX
;
7360 if (ANTIC_STORE_LIST (ptr
)
7361 && (tmp
= XEXP (ANTIC_STORE_LIST (ptr
), 0)) == NULL_RTX
)
7362 ANTIC_STORE_LIST (ptr
) = XEXP (ANTIC_STORE_LIST (ptr
), 1);
7366 /* Remove the stores that are not available anywhere, as there will
7367 be no opportunity to optimize them. */
7368 for (ptr
= pre_ldst_mems
, prev_next_ptr_ptr
= &pre_ldst_mems
;
7370 ptr
= *prev_next_ptr_ptr
)
7372 if (!AVAIL_STORE_LIST (ptr
))
7374 *prev_next_ptr_ptr
= ptr
->next
;
7375 free_ldst_entry (ptr
);
7378 prev_next_ptr_ptr
= &ptr
->next
;
7381 ret
= enumerate_ldsts ();
7385 fprintf (gcse_file
, "ST_avail and ST_antic (shown under loads..)\n");
7386 print_ldst_list (gcse_file
);
7394 /* Check to see if the load X is aliased with STORE_PATTERN. */
7397 load_kills_store (x
, store_pattern
)
7398 rtx x
, store_pattern
;
7400 if (true_dependence (x
, GET_MODE (x
), store_pattern
, rtx_addr_varies_p
))
7405 /* Go through the entire insn X, looking for any loads which might alias
7406 STORE_PATTERN. Return true if found. */
7409 find_loads (x
, store_pattern
)
7410 rtx x
, store_pattern
;
7419 if (GET_CODE (x
) == SET
)
7422 if (GET_CODE (x
) == MEM
)
7424 if (load_kills_store (x
, store_pattern
))
7428 /* Recursively process the insn. */
7429 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
7431 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0 && !ret
; i
--)
7434 ret
|= find_loads (XEXP (x
, i
), store_pattern
);
7435 else if (fmt
[i
] == 'E')
7436 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
7437 ret
|= find_loads (XVECEXP (x
, i
, j
), store_pattern
);
7442 /* Check if INSN kills the store pattern X (is aliased with it).
7443 Return true if it it does. */
7446 store_killed_in_insn (x
, x_regs
, insn
)
7447 rtx x
, x_regs
, insn
;
7454 if (GET_CODE (insn
) == CALL_INSN
)
7456 /* A normal or pure call might read from pattern,
7457 but a const call will not. */
7458 if (! CONST_OR_PURE_CALL_P (insn
) || pure_call_p (insn
))
7461 /* But even a const call reads its parameters. Check whether the
7462 base of some of registers used in mem is stack pointer. */
7463 for (reg
= x_regs
; reg
; reg
= XEXP (reg
, 1))
7465 base
= find_base_term (XEXP (reg
, 0));
7467 || (GET_CODE (base
) == ADDRESS
7468 && GET_MODE (base
) == Pmode
7469 && XEXP (base
, 0) == stack_pointer_rtx
))
7476 if (GET_CODE (PATTERN (insn
)) == SET
)
7478 rtx pat
= PATTERN (insn
);
7479 /* Check for memory stores to aliased objects. */
7480 if (GET_CODE (SET_DEST (pat
)) == MEM
&& !expr_equiv_p (SET_DEST (pat
), x
))
7481 /* pretend its a load and check for aliasing. */
7482 if (find_loads (SET_DEST (pat
), x
))
7484 return find_loads (SET_SRC (pat
), x
);
7487 return find_loads (PATTERN (insn
), x
);
7490 /* Returns true if the expression X is loaded or clobbered on or after INSN
7491 within basic block BB. REGS_SET_AFTER is bitmap of registers set in
7492 or after the insn. X_REGS is list of registers mentioned in X. If the store
7493 is killed, return the last insn in that it occurs in FAIL_INSN. */
7496 store_killed_after (x
, x_regs
, insn
, bb
, regs_set_after
, fail_insn
)
7497 rtx x
, x_regs
, insn
;
7499 int *regs_set_after
;
7502 rtx last
= bb
->end
, act
;
7504 if (!store_ops_ok (x_regs
, regs_set_after
))
7506 /* We do not know where it will happen. */
7508 *fail_insn
= NULL_RTX
;
7512 /* Scan from the end, so that fail_insn is determined correctly. */
7513 for (act
= last
; act
!= PREV_INSN (insn
); act
= PREV_INSN (act
))
7514 if (store_killed_in_insn (x
, x_regs
, act
))
7524 /* Returns true if the expression X is loaded or clobbered on or before INSN
7525 within basic block BB. X_REGS is list of registers mentioned in X.
7526 REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
7528 store_killed_before (x
, x_regs
, insn
, bb
, regs_set_before
)
7529 rtx x
, x_regs
, insn
;
7531 int *regs_set_before
;
7533 rtx first
= bb
->head
;
7535 if (!store_ops_ok (x_regs
, regs_set_before
))
7538 for ( ; insn
!= PREV_INSN (first
); insn
= PREV_INSN (insn
))
7539 if (store_killed_in_insn (x
, x_regs
, insn
))
7545 /* Fill in available, anticipatable, transparent and kill vectors in
7546 STORE_DATA, based on lists of available and anticipatable stores. */
7548 build_store_vectors ()
7551 int *regs_set_in_block
;
7553 struct ls_expr
* ptr
;
7556 /* Build the gen_vector. This is any store in the table which is not killed
7557 by aliasing later in its block. */
7558 ae_gen
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7559 sbitmap_vector_zero (ae_gen
, last_basic_block
);
7561 st_antloc
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7562 sbitmap_vector_zero (st_antloc
, last_basic_block
);
7564 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7566 for (st
= AVAIL_STORE_LIST (ptr
); st
!= NULL
; st
= XEXP (st
, 1))
7568 insn
= XEXP (st
, 0);
7569 bb
= BLOCK_FOR_INSN (insn
);
7571 /* If we've already seen an available expression in this block,
7572 we can delete this one (It occurs earlier in the block). We'll
7573 copy the SRC expression to an unused register in case there
7574 are any side effects. */
7575 if (TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
7577 rtx r
= gen_reg_rtx (GET_MODE (ptr
->pattern
));
7579 fprintf (gcse_file
, "Removing redundant store:\n");
7580 replace_store_insn (r
, XEXP (st
, 0), bb
);
7583 SET_BIT (ae_gen
[bb
->index
], ptr
->index
);
7586 for (st
= ANTIC_STORE_LIST (ptr
); st
!= NULL
; st
= XEXP (st
, 1))
7588 insn
= XEXP (st
, 0);
7589 bb
= BLOCK_FOR_INSN (insn
);
7590 SET_BIT (st_antloc
[bb
->index
], ptr
->index
);
7594 ae_kill
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7595 sbitmap_vector_zero (ae_kill
, last_basic_block
);
7597 transp
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7598 sbitmap_vector_zero (transp
, last_basic_block
);
7599 regs_set_in_block
= xmalloc (sizeof (int) * max_gcse_regno
);
7603 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
7604 regs_set_in_block
[regno
] = TEST_BIT (reg_set_in_block
[bb
->index
], regno
);
7606 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7608 if (store_killed_after (ptr
->pattern
, ptr
->pattern_regs
, bb
->head
,
7609 bb
, regs_set_in_block
, NULL
))
7611 /* It should not be necessary to consider the expression
7612 killed if it is both anticipatable and available. */
7613 if (!TEST_BIT (st_antloc
[bb
->index
], ptr
->index
)
7614 || !TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
7615 SET_BIT (ae_kill
[bb
->index
], ptr
->index
);
7618 SET_BIT (transp
[bb
->index
], ptr
->index
);
7622 free (regs_set_in_block
);
7626 dump_sbitmap_vector (gcse_file
, "st_antloc", "", st_antloc
, last_basic_block
);
7627 dump_sbitmap_vector (gcse_file
, "st_kill", "", ae_kill
, last_basic_block
);
7628 dump_sbitmap_vector (gcse_file
, "Transpt", "", transp
, last_basic_block
);
7629 dump_sbitmap_vector (gcse_file
, "st_avloc", "", ae_gen
, last_basic_block
);
7633 /* Insert an instruction at the beginning of a basic block, and update
7634 the BLOCK_HEAD if needed. */
7637 insert_insn_start_bb (insn
, bb
)
7641 /* Insert at start of successor block. */
7642 rtx prev
= PREV_INSN (bb
->head
);
7643 rtx before
= bb
->head
;
7646 if (GET_CODE (before
) != CODE_LABEL
7647 && (GET_CODE (before
) != NOTE
7648 || NOTE_LINE_NUMBER (before
) != NOTE_INSN_BASIC_BLOCK
))
7651 if (prev
== bb
->end
)
7653 before
= NEXT_INSN (before
);
7656 insn
= emit_insn_after (insn
, prev
);
7660 fprintf (gcse_file
, "STORE_MOTION insert store at start of BB %d:\n",
7662 print_inline_rtx (gcse_file
, insn
, 6);
7663 fprintf (gcse_file
, "\n");
7667 /* This routine will insert a store on an edge. EXPR is the ldst entry for
7668 the memory reference, and E is the edge to insert it on. Returns nonzero
7669 if an edge insertion was performed. */
7672 insert_store (expr
, e
)
7673 struct ls_expr
* expr
;
7680 /* We did all the deleted before this insert, so if we didn't delete a
7681 store, then we haven't set the reaching reg yet either. */
7682 if (expr
->reaching_reg
== NULL_RTX
)
7685 reg
= expr
->reaching_reg
;
7686 insn
= gen_move_insn (copy_rtx (expr
->pattern
), reg
);
7688 /* If we are inserting this expression on ALL predecessor edges of a BB,
7689 insert it at the start of the BB, and reset the insert bits on the other
7690 edges so we don't try to insert it on the other edges. */
7692 for (tmp
= e
->dest
->pred
; tmp
; tmp
= tmp
->pred_next
)
7694 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
7695 if (index
== EDGE_INDEX_NO_EDGE
)
7697 if (! TEST_BIT (pre_insert_map
[index
], expr
->index
))
7701 /* If tmp is NULL, we found an insertion on every edge, blank the
7702 insertion vector for these edges, and insert at the start of the BB. */
7703 if (!tmp
&& bb
!= EXIT_BLOCK_PTR
)
7705 for (tmp
= e
->dest
->pred
; tmp
; tmp
= tmp
->pred_next
)
7707 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
7708 RESET_BIT (pre_insert_map
[index
], expr
->index
);
7710 insert_insn_start_bb (insn
, bb
);
7714 /* We can't insert on this edge, so we'll insert at the head of the
7715 successors block. See Morgan, sec 10.5. */
7716 if ((e
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
7718 insert_insn_start_bb (insn
, bb
);
7722 insert_insn_on_edge (insn
, e
);
7726 fprintf (gcse_file
, "STORE_MOTION insert insn on edge (%d, %d):\n",
7727 e
->src
->index
, e
->dest
->index
);
7728 print_inline_rtx (gcse_file
, insn
, 6);
7729 fprintf (gcse_file
, "\n");
7735 /* This routine will replace a store with a SET to a specified register. */
7738 replace_store_insn (reg
, del
, bb
)
7744 insn
= gen_move_insn (reg
, SET_SRC (single_set (del
)));
7745 insn
= emit_insn_after (insn
, del
);
7750 "STORE_MOTION delete insn in BB %d:\n ", bb
->index
);
7751 print_inline_rtx (gcse_file
, del
, 6);
7752 fprintf (gcse_file
, "\nSTORE MOTION replaced with insn:\n ");
7753 print_inline_rtx (gcse_file
, insn
, 6);
7754 fprintf (gcse_file
, "\n");
7761 /* Delete a store, but copy the value that would have been stored into
7762 the reaching_reg for later storing. */
7765 delete_store (expr
, bb
)
7766 struct ls_expr
* expr
;
7771 if (expr
->reaching_reg
== NULL_RTX
)
7772 expr
->reaching_reg
= gen_reg_rtx (GET_MODE (expr
->pattern
));
7774 reg
= expr
->reaching_reg
;
7776 for (i
= AVAIL_STORE_LIST (expr
); i
; i
= XEXP (i
, 1))
7779 if (BLOCK_FOR_INSN (del
) == bb
)
7781 /* We know there is only one since we deleted redundant
7782 ones during the available computation. */
7783 replace_store_insn (reg
, del
, bb
);
7789 /* Free memory used by store motion. */
7792 free_store_memory ()
7797 sbitmap_vector_free (ae_gen
);
7799 sbitmap_vector_free (ae_kill
);
7801 sbitmap_vector_free (transp
);
7803 sbitmap_vector_free (st_antloc
);
7805 sbitmap_vector_free (pre_insert_map
);
7807 sbitmap_vector_free (pre_delete_map
);
7808 if (reg_set_in_block
)
7809 sbitmap_vector_free (reg_set_in_block
);
7811 ae_gen
= ae_kill
= transp
= st_antloc
= NULL
;
7812 pre_insert_map
= pre_delete_map
= reg_set_in_block
= NULL
;
7815 /* Perform store motion. Much like gcse, except we move expressions the
7816 other way by looking at the flowgraph in reverse. */
7823 struct ls_expr
* ptr
;
7824 int update_flow
= 0;
7828 fprintf (gcse_file
, "before store motion\n");
7829 print_rtl (gcse_file
, get_insns ());
7832 init_alias_analysis ();
7834 /* Find all the available and anticipatable stores. */
7835 num_stores
= compute_store_table ();
7836 if (num_stores
== 0)
7838 sbitmap_vector_free (reg_set_in_block
);
7839 end_alias_analysis ();
7843 /* Now compute kill & transp vectors. */
7844 build_store_vectors ();
7845 add_noreturn_fake_exit_edges ();
7847 edge_list
= pre_edge_rev_lcm (gcse_file
, num_stores
, transp
, ae_gen
,
7848 st_antloc
, ae_kill
, &pre_insert_map
,
7851 /* Now we want to insert the new stores which are going to be needed. */
7852 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7855 if (TEST_BIT (pre_delete_map
[bb
->index
], ptr
->index
))
7856 delete_store (ptr
, bb
);
7858 for (x
= 0; x
< NUM_EDGES (edge_list
); x
++)
7859 if (TEST_BIT (pre_insert_map
[x
], ptr
->index
))
7860 update_flow
|= insert_store (ptr
, INDEX_EDGE (edge_list
, x
));
7864 commit_edge_insertions ();
7866 free_store_memory ();
7867 free_edge_list (edge_list
);
7868 remove_fake_edges ();
7869 end_alias_analysis ();
7873 /* Entry point for jump bypassing optimization pass. */
7881 /* We do not construct an accurate cfg in functions which call
7882 setjmp, so just punt to be safe. */
7883 if (current_function_calls_setjmp
)
7886 /* For calling dump_foo fns from gdb. */
7887 debug_stderr
= stderr
;
7890 /* Identify the basic block information for this function, including
7891 successors and predecessors. */
7892 max_gcse_regno
= max_reg_num ();
7895 dump_flow_info (file
);
7897 /* Return if there's nothing to do. */
7898 if (n_basic_blocks
<= 1)
7901 /* Trying to perform global optimizations on flow graphs which have
7902 a high connectivity will take a long time and is unlikely to be
7903 particularly useful.
7905 In normal circumstances a cfg should have about twice as many edges
7906 as blocks. But we do not want to punish small functions which have
7907 a couple switch statements. So we require a relatively large number
7908 of basic blocks and the ratio of edges to blocks to be high. */
7909 if (n_basic_blocks
> 1000 && n_edges
/ n_basic_blocks
>= 20)
7911 if (warn_disabled_optimization
)
7912 warning ("BYPASS disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
7913 n_basic_blocks
, n_edges
/ n_basic_blocks
);
7917 /* If allocating memory for the cprop bitmap would take up too much
7918 storage it's better just to disable the optimization. */
7920 * SBITMAP_SET_SIZE (max_gcse_regno
)
7921 * sizeof (SBITMAP_ELT_TYPE
)) > MAX_GCSE_MEMORY
)
7923 if (warn_disabled_optimization
)
7924 warning ("GCSE disabled: %d basic blocks and %d registers",
7925 n_basic_blocks
, max_gcse_regno
);
7930 gcc_obstack_init (&gcse_obstack
);
7933 /* We need alias. */
7934 init_alias_analysis ();
7936 /* Record where pseudo-registers are set. This data is kept accurate
7937 during each pass. ??? We could also record hard-reg information here
7938 [since it's unchanging], however it is currently done during hash table
7941 It may be tempting to compute MEM set information here too, but MEM sets
7942 will be subject to code motion one day and thus we need to compute
7943 information about memory sets when we build the hash tables. */
7945 alloc_reg_set_mem (max_gcse_regno
);
7946 compute_sets (get_insns ());
7948 max_gcse_regno
= max_reg_num ();
7949 alloc_gcse_mem (get_insns ());
7950 changed
= one_cprop_pass (1, 1, 1);
7955 fprintf (file
, "BYPASS of %s: %d basic blocks, ",
7956 current_function_name
, n_basic_blocks
);
7957 fprintf (file
, "%d bytes\n\n", bytes_used
);
7960 obstack_free (&gcse_obstack
, NULL
);
7961 free_reg_set_mem ();
7963 /* We are finished with alias. */
7964 end_alias_analysis ();
7965 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
7970 #include "gt-gcse.h"