1 /* Global common subexpression elimination/Partial redundancy elimination
2 and global constant/copy propagation for GNU compiler.
3 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
24 - reordering of memory allocation and freeing to be more space efficient
25 - do rough calc of how many regs are needed in each block, and a rough
26 calc of how many regs are available in each class and use that to
27 throttle back the code in cases where RTX_COST is minimal.
28 - a store to the same address as a load does not kill the load if the
29 source of the store is also the destination of the load. Handling this
30 allows more load motion, particularly out of loops.
31 - ability to realloc sbitmap vectors would allow one initial computation
32 of reg_set_in_block with only subsequent additions, rather than
33 recomputing it for each pass
37 /* References searched while implementing this.
39 Compilers Principles, Techniques and Tools
43 Global Optimization by Suppression of Partial Redundancies
45 communications of the acm, Vol. 22, Num. 2, Feb. 1979
47 A Portable Machine-Independent Global Optimizer - Design and Measurements
49 Stanford Ph.D. thesis, Dec. 1983
51 A Fast Algorithm for Code Movement Optimization
53 SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988
55 A Solution to a Problem with Morel and Renvoise's
56 Global Optimization by Suppression of Partial Redundancies
57 K-H Drechsler, M.P. Stadel
58 ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988
60 Practical Adaptation of the Global Optimization
61 Algorithm of Morel and Renvoise
63 ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991
65 Efficiently Computing Static Single Assignment Form and the Control
67 R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck
68 ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991
71 J. Knoop, O. Ruthing, B. Steffen
72 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
74 What's In a Region? Or Computing Control Dependence Regions in Near-Linear
75 Time for Reducible Flow Control
77 ACM Letters on Programming Languages and Systems,
78 Vol. 2, Num. 1-4, Mar-Dec 1993
80 An Efficient Representation for Sparse Sets
81 Preston Briggs, Linda Torczon
82 ACM Letters on Programming Languages and Systems,
83 Vol. 2, Num. 1-4, Mar-Dec 1993
85 A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion
86 K-H Drechsler, M.P. Stadel
87 ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993
89 Partial Dead Code Elimination
90 J. Knoop, O. Ruthing, B. Steffen
91 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
93 Effective Partial Redundancy Elimination
94 P. Briggs, K.D. Cooper
95 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
97 The Program Structure Tree: Computing Control Regions in Linear Time
98 R. Johnson, D. Pearson, K. Pingali
99 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
101 Optimal Code Motion: Theory and Practice
102 J. Knoop, O. Ruthing, B. Steffen
103 ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994
105 The power of assignment motion
106 J. Knoop, O. Ruthing, B. Steffen
107 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
109 Global code motion / global value numbering
111 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
113 Value Driven Redundancy Elimination
115 Rice University Ph.D. thesis, Apr. 1996
119 Massively Scalar Compiler Project, Rice University, Sep. 1996
121 High Performance Compilers for Parallel Computing
125 Advanced Compiler Design and Implementation
127 Morgan Kaufmann, 1997
129 Building an Optimizing Compiler
133 People wishing to speed up the code here should read:
134 Elimination Algorithms for Data Flow Analysis
135 B.G. Ryder, M.C. Paull
136 ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986
138 How to Analyze Large Programs Efficiently and Informatively
139 D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck
140 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
142 People wishing to do something different can find various possibilities
143 in the above papers and elsewhere.
153 #include "hard-reg-set.h"
156 #include "insn-config.h"
158 #include "basic-block.h"
160 #include "function.h"
168 #define obstack_chunk_alloc gmalloc
169 #define obstack_chunk_free free
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. */
182 #define FOLLOW_BACK_EDGES 1
184 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
185 are a superset of those done by GCSE.
187 We perform the following steps:
189 1) Compute basic block information.
191 2) Compute table of places where registers are set.
193 3) Perform copy/constant propagation.
195 4) Perform global cse.
197 5) Perform another pass of copy/constant propagation.
199 Two passes of copy/constant propagation are done because the first one
200 enables more GCSE and the second one helps to clean up the copies that
201 GCSE creates. This is needed more for PRE than for Classic because Classic
202 GCSE will try to use an existing register containing the common
203 subexpression rather than create a new one. This is harder to do for PRE
204 because of the code motion (which Classic GCSE doesn't do).
206 Expressions we are interested in GCSE-ing are of the form
207 (set (pseudo-reg) (expression)).
208 Function want_to_gcse_p says what these are.
210 PRE handles moving invariant expressions out of loops (by treating them as
211 partially redundant).
213 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
214 assignment) based GVN (global value numbering). L. T. Simpson's paper
215 (Rice University) on value numbering is a useful reference for this.
217 **********************
219 We used to support multiple passes but there are diminishing returns in
220 doing so. The first pass usually makes 90% of the changes that are doable.
221 A second pass can make a few more changes made possible by the first pass.
222 Experiments show any further passes don't make enough changes to justify
225 A study of spec92 using an unlimited number of passes:
226 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
227 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
228 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
230 It was found doing copy propagation between each pass enables further
233 PRE is quite expensive in complicated functions because the DFA can take
234 awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can
235 be modified if one wants to experiment.
237 **********************
239 The steps for PRE are:
241 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
243 2) Perform the data flow analysis for PRE.
245 3) Delete the redundant instructions
247 4) Insert the required copies [if any] that make the partially
248 redundant instructions fully redundant.
250 5) For other reaching expressions, insert an instruction to copy the value
251 to a newly created pseudo that will reach the redundant instruction.
253 The deletion is done first so that when we do insertions we
254 know which pseudo reg to use.
256 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
257 argue it is not. The number of iterations for the algorithm to converge
258 is typically 2-4 so I don't view it as that expensive (relatively speaking).
260 PRE GCSE depends heavily on the second CSE pass to clean up the copies
261 we create. To make an expression reach the place where it's redundant,
262 the result of the expression is copied to a new register, and the redundant
263 expression is deleted by replacing it with this new register. Classic GCSE
264 doesn't have this problem as much as it computes the reaching defs of
265 each register in each block and thus can try to use an existing register.
267 **********************
269 A fair bit of simplicity is created by creating small functions for simple
270 tasks, even when the function is only called in one place. This may
271 measurably slow things down [or may not] by creating more function call
272 overhead than is necessary. The source is laid out so that it's trivial
273 to make the affected functions inline so that one can measure what speed
274 up, if any, can be achieved, and maybe later when things settle things can
277 Help stamp out big monolithic functions! */
279 /* GCSE global vars. */
282 static FILE *gcse_file
;
284 /* Note whether or not we should run jump optimization after gcse. We
285 want to do this for two cases.
287 * If we changed any jumps via cprop.
289 * If we added any labels via edge splitting. */
291 static int run_jump_opt_after_gcse
;
293 /* Bitmaps are normally not included in debugging dumps.
294 However it's useful to be able to print them from GDB.
295 We could create special functions for this, but it's simpler to
296 just allow passing stderr to the dump_foo fns. Since stderr can
297 be a macro, we store a copy here. */
298 static FILE *debug_stderr
;
300 /* An obstack for our working variables. */
301 static struct obstack gcse_obstack
;
303 /* Non-zero for each mode that supports (set (reg) (reg)).
304 This is trivially true for integer and floating point values.
305 It may or may not be true for condition codes. */
306 static char can_copy_p
[(int) NUM_MACHINE_MODES
];
308 /* Non-zero if can_copy_p has been initialized. */
309 static int can_copy_init_p
;
311 struct reg_use
{rtx reg_rtx
; };
313 /* Hash table of expressions. */
317 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
319 /* Index in the available expression bitmaps. */
321 /* Next entry with the same hash. */
322 struct expr
*next_same_hash
;
323 /* List of anticipatable occurrences in basic blocks in the function.
324 An "anticipatable occurrence" is one that is the first occurrence in the
325 basic block, the operands are not modified in the basic block prior
326 to the occurrence and the output is not used between the start of
327 the block and the occurrence. */
328 struct occr
*antic_occr
;
329 /* List of available occurrence in basic blocks in the function.
330 An "available occurrence" is one that is the last occurrence in the
331 basic block and the operands are not modified by following statements in
332 the basic block [including this insn]. */
333 struct occr
*avail_occr
;
334 /* Non-null if the computation is PRE redundant.
335 The value is the newly created pseudo-reg to record a copy of the
336 expression in all the places that reach the redundant copy. */
340 /* Occurrence of an expression.
341 There is one per basic block. If a pattern appears more than once the
342 last appearance is used [or first for anticipatable expressions]. */
346 /* Next occurrence of this expression. */
348 /* The insn that computes the expression. */
350 /* Non-zero if this [anticipatable] occurrence has been deleted. */
352 /* Non-zero if this [available] occurrence has been copied to
354 /* ??? This is mutually exclusive with deleted_p, so they could share
359 /* Expression and copy propagation hash tables.
360 Each hash table is an array of buckets.
361 ??? It is known that if it were an array of entries, structure elements
362 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
363 not clear whether in the final analysis a sufficient amount of memory would
364 be saved as the size of the available expression bitmaps would be larger
365 [one could build a mapping table without holes afterwards though].
366 Someday I'll perform the computation and figure it out. */
368 /* Total size of the expression hash table, in elements. */
369 static unsigned int expr_hash_table_size
;
372 This is an array of `expr_hash_table_size' elements. */
373 static struct expr
**expr_hash_table
;
375 /* Total size of the copy propagation hash table, in elements. */
376 static unsigned int set_hash_table_size
;
379 This is an array of `set_hash_table_size' elements. */
380 static struct expr
**set_hash_table
;
382 /* Mapping of uids to cuids.
383 Only real insns get cuids. */
384 static int *uid_cuid
;
386 /* Highest UID in UID_CUID. */
389 /* Get the cuid of an insn. */
390 #ifdef ENABLE_CHECKING
391 #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
393 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
396 /* Number of cuids. */
399 /* Mapping of cuids to insns. */
400 static rtx
*cuid_insn
;
402 /* Get insn from cuid. */
403 #define CUID_INSN(CUID) (cuid_insn[CUID])
405 /* Maximum register number in function prior to doing gcse + 1.
406 Registers created during this pass have regno >= max_gcse_regno.
407 This is named with "gcse" to not collide with global of same name. */
408 static unsigned int max_gcse_regno
;
410 /* Maximum number of cse-able expressions found. */
413 /* Maximum number of assignments for copy propagation found. */
416 /* Table of registers that are modified.
418 For each register, each element is a list of places where the pseudo-reg
421 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
422 requires knowledge of which blocks kill which regs [and thus could use
423 a bitmap instead of the lists `reg_set_table' uses].
425 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
426 num-regs) [however perhaps it may be useful to keep the data as is]. One
427 advantage of recording things this way is that `reg_set_table' is fairly
428 sparse with respect to pseudo regs but for hard regs could be fairly dense
429 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
430 up functions like compute_transp since in the case of pseudo-regs we only
431 need to iterate over the number of times a pseudo-reg is set, not over the
432 number of basic blocks [clearly there is a bit of a slow down in the cases
433 where a pseudo is set more than once in a block, however it is believed
434 that the net effect is to speed things up]. This isn't done for hard-regs
435 because recording call-clobbered hard-regs in `reg_set_table' at each
436 function call can consume a fair bit of memory, and iterating over
437 hard-regs stored this way in compute_transp will be more expensive. */
439 typedef struct reg_set
441 /* The next setting of this register. */
442 struct reg_set
*next
;
443 /* The insn where it was set. */
447 static reg_set
**reg_set_table
;
449 /* Size of `reg_set_table'.
450 The table starts out at max_gcse_regno + slop, and is enlarged as
452 static int reg_set_table_size
;
454 /* Amount to grow `reg_set_table' by when it's full. */
455 #define REG_SET_TABLE_SLOP 100
457 /* This is a list of expressions which are MEMs and will be used by load
459 Load motion tracks MEMs which aren't killed by
460 anything except itself. (ie, loads and stores to a single location).
461 We can then allow movement of these MEM refs with a little special
462 allowance. (all stores copy the same value to the reaching reg used
463 for the loads). This means all values used to store into memory must have
464 no side effects so we can re-issue the setter value.
465 Store Motion uses this structure as an expression table to track stores
466 which look interesting, and might be moveable towards the exit block. */
470 struct expr
* expr
; /* Gcse expression reference for LM. */
471 rtx pattern
; /* Pattern of this mem. */
472 rtx loads
; /* INSN list of loads seen. */
473 rtx stores
; /* INSN list of stores seen. */
474 struct ls_expr
* next
; /* Next in the list. */
475 int invalid
; /* Invalid for some reason. */
476 int index
; /* If it maps to a bitmap index. */
477 int hash_index
; /* Index when in a hash table. */
478 rtx reaching_reg
; /* Register to use when re-writing. */
481 /* Head of the list of load/store memory refs. */
482 static struct ls_expr
* pre_ldst_mems
= NULL
;
484 /* Bitmap containing one bit for each register in the program.
485 Used when performing GCSE to track which registers have been set since
486 the start of the basic block. */
487 static regset reg_set_bitmap
;
489 /* For each block, a bitmap of registers set in the block.
490 This is used by expr_killed_p and compute_transp.
491 It is computed during hash table computation and not by compute_sets
492 as it includes registers added since the last pass (or between cprop and
493 gcse) and it's currently not easy to realloc sbitmap vectors. */
494 static sbitmap
*reg_set_in_block
;
496 /* Array, indexed by basic block number for a list of insns which modify
497 memory within that block. */
498 static rtx
* modify_mem_list
;
499 bitmap modify_mem_list_set
;
501 /* This array parallels modify_mem_list, but is kept canonicalized. */
502 static rtx
* canon_modify_mem_list
;
503 bitmap canon_modify_mem_list_set
;
504 /* Various variables for statistics gathering. */
506 /* Memory used in a pass.
507 This isn't intended to be absolutely precise. Its intent is only
508 to keep an eye on memory usage. */
509 static int bytes_used
;
511 /* GCSE substitutions made. */
512 static int gcse_subst_count
;
513 /* Number of copy instructions created. */
514 static int gcse_create_count
;
515 /* Number of constants propagated. */
516 static int const_prop_count
;
517 /* Number of copys propagated. */
518 static int copy_prop_count
;
520 /* These variables are used by classic GCSE.
521 Normally they'd be defined a bit later, but `rd_gen' needs to
522 be declared sooner. */
524 /* Each block has a bitmap of each type.
525 The length of each blocks bitmap is:
527 max_cuid - for reaching definitions
528 n_exprs - for available expressions
530 Thus we view the bitmaps as 2 dimensional arrays. i.e.
531 rd_kill[block_num][cuid_num]
532 ae_kill[block_num][expr_num] */
534 /* For reaching defs */
535 static sbitmap
*rd_kill
, *rd_gen
, *reaching_defs
, *rd_out
;
537 /* for available exprs */
538 static sbitmap
*ae_kill
, *ae_gen
, *ae_in
, *ae_out
;
540 /* Objects of this type are passed around by the null-pointer check
542 struct null_pointer_info
544 /* The basic block being processed. */
545 basic_block current_block
;
546 /* The first register to be handled in this pass. */
547 unsigned int min_reg
;
548 /* One greater than the last register to be handled in this pass. */
549 unsigned int max_reg
;
550 sbitmap
*nonnull_local
;
551 sbitmap
*nonnull_killed
;
554 static void compute_can_copy
PARAMS ((void));
555 static char *gmalloc
PARAMS ((unsigned int));
556 static char *grealloc
PARAMS ((char *, unsigned int));
557 static char *gcse_alloc
PARAMS ((unsigned long));
558 static void alloc_gcse_mem
PARAMS ((rtx
));
559 static void free_gcse_mem
PARAMS ((void));
560 static void alloc_reg_set_mem
PARAMS ((int));
561 static void free_reg_set_mem
PARAMS ((void));
562 static int get_bitmap_width
PARAMS ((int, int, int));
563 static void record_one_set
PARAMS ((int, rtx
));
564 static void record_set_info
PARAMS ((rtx
, rtx
, void *));
565 static void compute_sets
PARAMS ((rtx
));
566 static void hash_scan_insn
PARAMS ((rtx
, int, int));
567 static void hash_scan_set
PARAMS ((rtx
, rtx
, int));
568 static void hash_scan_clobber
PARAMS ((rtx
, rtx
));
569 static void hash_scan_call
PARAMS ((rtx
, rtx
));
570 static int want_to_gcse_p
PARAMS ((rtx
));
571 static int oprs_unchanged_p
PARAMS ((rtx
, rtx
, int));
572 static int oprs_anticipatable_p
PARAMS ((rtx
, rtx
));
573 static int oprs_available_p
PARAMS ((rtx
, rtx
));
574 static void insert_expr_in_table
PARAMS ((rtx
, enum machine_mode
, rtx
,
576 static void insert_set_in_table
PARAMS ((rtx
, rtx
));
577 static unsigned int hash_expr
PARAMS ((rtx
, enum machine_mode
, int *, int));
578 static unsigned int hash_expr_1
PARAMS ((rtx
, enum machine_mode
, int *));
579 static unsigned int hash_string_1
PARAMS ((const char *));
580 static unsigned int hash_set
PARAMS ((int, int));
581 static int expr_equiv_p
PARAMS ((rtx
, rtx
));
582 static void record_last_reg_set_info
PARAMS ((rtx
, int));
583 static void record_last_mem_set_info
PARAMS ((rtx
));
584 static void record_last_set_info
PARAMS ((rtx
, rtx
, void *));
585 static void compute_hash_table
PARAMS ((int));
586 static void alloc_set_hash_table
PARAMS ((int));
587 static void free_set_hash_table
PARAMS ((void));
588 static void compute_set_hash_table
PARAMS ((void));
589 static void alloc_expr_hash_table
PARAMS ((unsigned int));
590 static void free_expr_hash_table
PARAMS ((void));
591 static void compute_expr_hash_table
PARAMS ((void));
592 static void dump_hash_table
PARAMS ((FILE *, const char *, struct expr
**,
594 static struct expr
*lookup_expr
PARAMS ((rtx
));
595 static struct expr
*lookup_set
PARAMS ((unsigned int, rtx
));
596 static struct expr
*next_set
PARAMS ((unsigned int, struct expr
*));
597 static void reset_opr_set_tables
PARAMS ((void));
598 static int oprs_not_set_p
PARAMS ((rtx
, rtx
));
599 static void mark_call
PARAMS ((rtx
));
600 static void mark_set
PARAMS ((rtx
, rtx
));
601 static void mark_clobber
PARAMS ((rtx
, rtx
));
602 static void mark_oprs_set
PARAMS ((rtx
));
603 static void alloc_cprop_mem
PARAMS ((int, int));
604 static void free_cprop_mem
PARAMS ((void));
605 static void compute_transp
PARAMS ((rtx
, int, sbitmap
*, int));
606 static void compute_transpout
PARAMS ((void));
607 static void compute_local_properties
PARAMS ((sbitmap
*, sbitmap
*, sbitmap
*,
609 static void compute_cprop_data
PARAMS ((void));
610 static void find_used_regs
PARAMS ((rtx
*, void *));
611 static int try_replace_reg
PARAMS ((rtx
, rtx
, rtx
));
612 static struct expr
*find_avail_set
PARAMS ((int, rtx
));
613 static int cprop_jump
PARAMS ((basic_block
, rtx
, rtx
, rtx
, rtx
));
614 static void mems_conflict_for_gcse_p
PARAMS ((rtx
, rtx
, void *));
615 static int load_killed_in_block_p
PARAMS ((basic_block
, int, rtx
, int));
616 static void canon_list_insert
PARAMS ((rtx
, rtx
, void *));
617 static int cprop_insn
PARAMS ((rtx
, int));
618 static int cprop
PARAMS ((int));
619 static int one_cprop_pass
PARAMS ((int, int));
620 static bool constprop_register
PARAMS ((rtx
, rtx
, rtx
, int));
621 static struct expr
*find_bypass_set
PARAMS ((int, int));
622 static int bypass_block
PARAMS ((basic_block
, rtx
, rtx
));
623 static int bypass_conditional_jumps
PARAMS ((void));
624 static void alloc_pre_mem
PARAMS ((int, int));
625 static void free_pre_mem
PARAMS ((void));
626 static void compute_pre_data
PARAMS ((void));
627 static int pre_expr_reaches_here_p
PARAMS ((basic_block
, struct expr
*,
629 static void insert_insn_end_bb
PARAMS ((struct expr
*, basic_block
, int));
630 static void pre_insert_copy_insn
PARAMS ((struct expr
*, rtx
));
631 static void pre_insert_copies
PARAMS ((void));
632 static int pre_delete
PARAMS ((void));
633 static int pre_gcse
PARAMS ((void));
634 static int one_pre_gcse_pass
PARAMS ((int));
635 static void add_label_notes
PARAMS ((rtx
, rtx
));
636 static void alloc_code_hoist_mem
PARAMS ((int, int));
637 static void free_code_hoist_mem
PARAMS ((void));
638 static void compute_code_hoist_vbeinout
PARAMS ((void));
639 static void compute_code_hoist_data
PARAMS ((void));
640 static int hoist_expr_reaches_here_p
PARAMS ((basic_block
, int, basic_block
,
642 static void hoist_code
PARAMS ((void));
643 static int one_code_hoisting_pass
PARAMS ((void));
644 static void alloc_rd_mem
PARAMS ((int, int));
645 static void free_rd_mem
PARAMS ((void));
646 static void handle_rd_kill_set
PARAMS ((rtx
, int, basic_block
));
647 static void compute_kill_rd
PARAMS ((void));
648 static void compute_rd
PARAMS ((void));
649 static void alloc_avail_expr_mem
PARAMS ((int, int));
650 static void free_avail_expr_mem
PARAMS ((void));
651 static void compute_ae_gen
PARAMS ((void));
652 static int expr_killed_p
PARAMS ((rtx
, basic_block
));
653 static void compute_ae_kill
PARAMS ((sbitmap
*, sbitmap
*));
654 static int expr_reaches_here_p
PARAMS ((struct occr
*, struct expr
*,
656 static rtx computing_insn
PARAMS ((struct expr
*, rtx
));
657 static int def_reaches_here_p
PARAMS ((rtx
, rtx
));
658 static int can_disregard_other_sets
PARAMS ((struct reg_set
**, rtx
, int));
659 static int handle_avail_expr
PARAMS ((rtx
, struct expr
*));
660 static int classic_gcse
PARAMS ((void));
661 static int one_classic_gcse_pass
PARAMS ((int));
662 static void invalidate_nonnull_info
PARAMS ((rtx
, rtx
, void *));
663 static int delete_null_pointer_checks_1
PARAMS ((unsigned int *,
664 sbitmap
*, sbitmap
*,
665 struct null_pointer_info
*));
666 static rtx process_insert_insn
PARAMS ((struct expr
*));
667 static int pre_edge_insert
PARAMS ((struct edge_list
*, struct expr
**));
668 static int expr_reaches_here_p_work
PARAMS ((struct occr
*, struct expr
*,
669 basic_block
, int, char *));
670 static int pre_expr_reaches_here_p_work
PARAMS ((basic_block
, struct expr
*,
671 basic_block
, char *));
672 static struct ls_expr
* ldst_entry
PARAMS ((rtx
));
673 static void free_ldst_entry
PARAMS ((struct ls_expr
*));
674 static void free_ldst_mems
PARAMS ((void));
675 static void print_ldst_list
PARAMS ((FILE *));
676 static struct ls_expr
* find_rtx_in_ldst
PARAMS ((rtx
));
677 static int enumerate_ldsts
PARAMS ((void));
678 static inline struct ls_expr
* first_ls_expr
PARAMS ((void));
679 static inline struct ls_expr
* next_ls_expr
PARAMS ((struct ls_expr
*));
680 static int simple_mem
PARAMS ((rtx
));
681 static void invalidate_any_buried_refs
PARAMS ((rtx
));
682 static void compute_ld_motion_mems
PARAMS ((void));
683 static void trim_ld_motion_mems
PARAMS ((void));
684 static void update_ld_motion_stores
PARAMS ((struct expr
*));
685 static void reg_set_info
PARAMS ((rtx
, rtx
, void *));
686 static int store_ops_ok
PARAMS ((rtx
, basic_block
));
687 static void find_moveable_store
PARAMS ((rtx
));
688 static int compute_store_table
PARAMS ((void));
689 static int load_kills_store
PARAMS ((rtx
, rtx
));
690 static int find_loads
PARAMS ((rtx
, rtx
));
691 static int store_killed_in_insn
PARAMS ((rtx
, rtx
));
692 static int store_killed_after
PARAMS ((rtx
, rtx
, basic_block
));
693 static int store_killed_before
PARAMS ((rtx
, rtx
, basic_block
));
694 static void build_store_vectors
PARAMS ((void));
695 static void insert_insn_start_bb
PARAMS ((rtx
, basic_block
));
696 static int insert_store
PARAMS ((struct ls_expr
*, edge
));
697 static void replace_store_insn
PARAMS ((rtx
, rtx
, basic_block
));
698 static void delete_store
PARAMS ((struct ls_expr
*,
700 static void free_store_memory
PARAMS ((void));
701 static void store_motion
PARAMS ((void));
702 static void free_insn_expr_list_list
PARAMS ((rtx
*));
703 static void clear_modify_mem_tables
PARAMS ((void));
704 static void free_modify_mem_tables
PARAMS ((void));
705 static rtx gcse_emit_move_after
PARAMS ((rtx
, rtx
, rtx
));
706 static bool do_local_cprop
PARAMS ((rtx
, rtx
, int));
707 static void local_cprop_pass
PARAMS ((int));
709 /* Entry point for global common subexpression elimination.
710 F is the first instruction in the function. */
718 /* Bytes used at start of pass. */
719 int initial_bytes_used
;
720 /* Maximum number of bytes used by a pass. */
722 /* Point to release obstack data from for each pass. */
723 char *gcse_obstack_bottom
;
725 /* Insertion of instructions on edges can create new basic blocks; we
726 need the original basic block count so that we can properly deallocate
727 arrays sized on the number of basic blocks originally in the cfg. */
729 /* We do not construct an accurate cfg in functions which call
730 setjmp, so just punt to be safe. */
731 if (current_function_calls_setjmp
)
734 /* Assume that we do not need to run jump optimizations after gcse. */
735 run_jump_opt_after_gcse
= 0;
737 /* For calling dump_foo fns from gdb. */
738 debug_stderr
= stderr
;
741 /* Identify the basic block information for this function, including
742 successors and predecessors. */
743 max_gcse_regno
= max_reg_num ();
746 dump_flow_info (file
);
748 orig_bb_count
= n_basic_blocks
;
749 /* Return if there's nothing to do. */
750 if (n_basic_blocks
<= 1)
753 /* Trying to perform global optimizations on flow graphs which have
754 a high connectivity will take a long time and is unlikely to be
757 In normal circumstances a cfg should have about twice as many edges
758 as blocks. But we do not want to punish small functions which have
759 a couple switch statements. So we require a relatively large number
760 of basic blocks and the ratio of edges to blocks to be high. */
761 if (n_basic_blocks
> 1000 && n_edges
/ n_basic_blocks
>= 20)
763 if (warn_disabled_optimization
)
764 warning ("GCSE disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
765 n_basic_blocks
, n_edges
/ n_basic_blocks
);
769 /* If allocating memory for the cprop bitmap would take up too much
770 storage it's better just to disable the optimization. */
772 * SBITMAP_SET_SIZE (max_gcse_regno
)
773 * sizeof (SBITMAP_ELT_TYPE
)) > MAX_GCSE_MEMORY
)
775 if (warn_disabled_optimization
)
776 warning ("GCSE disabled: %d basic blocks and %d registers",
777 n_basic_blocks
, max_gcse_regno
);
782 /* See what modes support reg/reg copy operations. */
783 if (! can_copy_init_p
)
789 gcc_obstack_init (&gcse_obstack
);
793 init_alias_analysis ();
794 /* Record where pseudo-registers are set. This data is kept accurate
795 during each pass. ??? We could also record hard-reg information here
796 [since it's unchanging], however it is currently done during hash table
799 It may be tempting to compute MEM set information here too, but MEM sets
800 will be subject to code motion one day and thus we need to compute
801 information about memory sets when we build the hash tables. */
803 alloc_reg_set_mem (max_gcse_regno
);
807 initial_bytes_used
= bytes_used
;
809 gcse_obstack_bottom
= gcse_alloc (1);
811 while (changed
&& pass
< MAX_GCSE_PASSES
)
815 fprintf (file
, "GCSE pass %d\n\n", pass
+ 1);
817 /* Initialize bytes_used to the space for the pred/succ lists,
818 and the reg_set_table data. */
819 bytes_used
= initial_bytes_used
;
821 /* Each pass may create new registers, so recalculate each time. */
822 max_gcse_regno
= max_reg_num ();
826 /* Don't allow constant propagation to modify jumps
828 changed
= one_cprop_pass (pass
+ 1, 0);
831 changed
|= one_classic_gcse_pass (pass
+ 1);
834 changed
|= one_pre_gcse_pass (pass
+ 1);
835 /* We may have just created new basic blocks. Release and
836 recompute various things which are sized on the number of
840 free_modify_mem_tables ();
842 = (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
843 canon_modify_mem_list
844 = (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
845 memset ((char *) modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
846 memset ((char *) canon_modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
847 orig_bb_count
= n_basic_blocks
;
850 alloc_reg_set_mem (max_reg_num ());
852 run_jump_opt_after_gcse
= 1;
855 if (max_pass_bytes
< bytes_used
)
856 max_pass_bytes
= bytes_used
;
858 /* Free up memory, then reallocate for code hoisting. We can
859 not re-use the existing allocated memory because the tables
860 will not have info for the insns or registers created by
861 partial redundancy elimination. */
864 /* It does not make sense to run code hoisting unless we optimizing
865 for code size -- it rarely makes programs faster, and can make
866 them bigger if we did partial redundancy elimination (when optimizing
867 for space, we use a classic gcse algorithm instead of partial
868 redundancy algorithms). */
871 max_gcse_regno
= max_reg_num ();
873 changed
|= one_code_hoisting_pass ();
876 if (max_pass_bytes
< bytes_used
)
877 max_pass_bytes
= bytes_used
;
882 fprintf (file
, "\n");
886 obstack_free (&gcse_obstack
, gcse_obstack_bottom
);
890 /* Do one last pass of copy propagation, including cprop into
891 conditional jumps. */
893 max_gcse_regno
= max_reg_num ();
895 /* This time, go ahead and allow cprop to alter jumps. */
896 one_cprop_pass (pass
+ 1, 1);
901 fprintf (file
, "GCSE of %s: %d basic blocks, ",
902 current_function_name
, n_basic_blocks
);
903 fprintf (file
, "%d pass%s, %d bytes\n\n",
904 pass
, pass
> 1 ? "es" : "", max_pass_bytes
);
907 obstack_free (&gcse_obstack
, NULL
);
909 /* We are finished with alias. */
910 end_alias_analysis ();
911 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
913 /* Store motion disabled until it is fixed. */
914 if (0 && !optimize_size
&& flag_gcse_sm
)
916 /* Record where pseudo-registers are set. */
917 return run_jump_opt_after_gcse
;
920 /* Misc. utilities. */
922 /* Compute which modes support reg/reg copy operations. */
928 #ifndef AVOID_CCMODE_COPIES
931 memset (can_copy_p
, 0, NUM_MACHINE_MODES
);
934 for (i
= 0; i
< NUM_MACHINE_MODES
; i
++)
935 if (GET_MODE_CLASS (i
) == MODE_CC
)
937 #ifdef AVOID_CCMODE_COPIES
940 reg
= gen_rtx_REG ((enum machine_mode
) i
, LAST_VIRTUAL_REGISTER
+ 1);
941 insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, reg
));
942 if (recog (PATTERN (insn
), insn
, NULL
) >= 0)
952 /* Cover function to xmalloc to record bytes allocated. */
959 return xmalloc (size
);
962 /* Cover function to xrealloc.
963 We don't record the additional size since we don't know it.
964 It won't affect memory usage stats much anyway. */
971 return xrealloc (ptr
, size
);
974 /* Cover function to obstack_alloc.
975 We don't need to record the bytes allocated here since
976 obstack_chunk_alloc is set to gmalloc. */
982 return (char *) obstack_alloc (&gcse_obstack
, size
);
985 /* Allocate memory for the cuid mapping array,
986 and reg/memory set tracking tables.
988 This is called at the start of each pass. */
997 /* Find the largest UID and create a mapping from UIDs to CUIDs.
998 CUIDs are like UIDs except they increase monotonically, have no gaps,
999 and only apply to real insns. */
1001 max_uid
= get_max_uid ();
1002 n
= (max_uid
+ 1) * sizeof (int);
1003 uid_cuid
= (int *) gmalloc (n
);
1004 memset ((char *) uid_cuid
, 0, n
);
1005 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
1008 uid_cuid
[INSN_UID (insn
)] = i
++;
1010 uid_cuid
[INSN_UID (insn
)] = i
;
1013 /* Create a table mapping cuids to insns. */
1016 n
= (max_cuid
+ 1) * sizeof (rtx
);
1017 cuid_insn
= (rtx
*) gmalloc (n
);
1018 memset ((char *) cuid_insn
, 0, n
);
1019 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
1021 CUID_INSN (i
++) = insn
;
1023 /* Allocate vars to track sets of regs. */
1024 reg_set_bitmap
= BITMAP_XMALLOC ();
1026 /* Allocate vars to track sets of regs, memory per block. */
1027 reg_set_in_block
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
,
1029 /* Allocate array to keep a list of insns which modify memory in each
1031 modify_mem_list
= (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
1032 canon_modify_mem_list
= (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
1033 memset ((char *) modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
1034 memset ((char *) canon_modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
1035 modify_mem_list_set
= BITMAP_XMALLOC ();
1036 canon_modify_mem_list_set
= BITMAP_XMALLOC ();
1039 /* Free memory allocated by alloc_gcse_mem. */
1047 BITMAP_XFREE (reg_set_bitmap
);
1049 sbitmap_vector_free (reg_set_in_block
);
1050 free_modify_mem_tables ();
1051 BITMAP_XFREE (modify_mem_list_set
);
1052 BITMAP_XFREE (canon_modify_mem_list_set
);
1055 /* Many of the global optimization algorithms work by solving dataflow
1056 equations for various expressions. Initially, some local value is
1057 computed for each expression in each block. Then, the values across the
1058 various blocks are combined (by following flow graph edges) to arrive at
1059 global values. Conceptually, each set of equations is independent. We
1060 may therefore solve all the equations in parallel, solve them one at a
1061 time, or pick any intermediate approach.
1063 When you're going to need N two-dimensional bitmaps, each X (say, the
1064 number of blocks) by Y (say, the number of expressions), call this
1065 function. It's not important what X and Y represent; only that Y
1066 correspond to the things that can be done in parallel. This function will
1067 return an appropriate chunking factor C; you should solve C sets of
1068 equations in parallel. By going through this function, we can easily
1069 trade space against time; by solving fewer equations in parallel we use
1073 get_bitmap_width (n
, x
, y
)
1078 /* It's not really worth figuring out *exactly* how much memory will
1079 be used by a particular choice. The important thing is to get
1080 something approximately right. */
1081 size_t max_bitmap_memory
= 10 * 1024 * 1024;
1083 /* The number of bytes we'd use for a single column of minimum
1085 size_t column_size
= n
* x
* sizeof (SBITMAP_ELT_TYPE
);
1087 /* Often, it's reasonable just to solve all the equations in
1089 if (column_size
* SBITMAP_SET_SIZE (y
) <= max_bitmap_memory
)
1092 /* Otherwise, pick the largest width we can, without going over the
1094 return SBITMAP_ELT_BITS
* ((max_bitmap_memory
+ column_size
- 1)
1098 /* Compute the local properties of each recorded expression.
1100 Local properties are those that are defined by the block, irrespective of
1103 An expression is transparent in a block if its operands are not modified
1106 An expression is computed (locally available) in a block if it is computed
1107 at least once and expression would contain the same value if the
1108 computation was moved to the end of the block.
1110 An expression is locally anticipatable in a block if it is computed at
1111 least once and expression would contain the same value if the computation
1112 was moved to the beginning of the block.
1114 We call this routine for cprop, pre and code hoisting. They all compute
1115 basically the same information and thus can easily share this code.
1117 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1118 properties. If NULL, then it is not necessary to compute or record that
1119 particular property.
1121 SETP controls which hash table to look at. If zero, this routine looks at
1122 the expr hash table; if nonzero this routine looks at the set hash table.
1123 Additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1127 compute_local_properties (transp
, comp
, antloc
, setp
)
1133 unsigned int i
, hash_table_size
;
1134 struct expr
**hash_table
;
1136 /* Initialize any bitmaps that were passed in. */
1140 sbitmap_vector_zero (transp
, last_basic_block
);
1142 sbitmap_vector_ones (transp
, last_basic_block
);
1146 sbitmap_vector_zero (comp
, last_basic_block
);
1148 sbitmap_vector_zero (antloc
, last_basic_block
);
1150 /* We use the same code for cprop, pre and hoisting. For cprop
1151 we care about the set hash table, for pre and hoisting we
1152 care about the expr hash table. */
1153 hash_table_size
= setp
? set_hash_table_size
: expr_hash_table_size
;
1154 hash_table
= setp
? set_hash_table
: expr_hash_table
;
1156 for (i
= 0; i
< hash_table_size
; i
++)
1160 for (expr
= hash_table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1162 int indx
= expr
->bitmap_index
;
1165 /* The expression is transparent in this block if it is not killed.
1166 We start by assuming all are transparent [none are killed], and
1167 then reset the bits for those that are. */
1169 compute_transp (expr
->expr
, indx
, transp
, setp
);
1171 /* The occurrences recorded in antic_occr are exactly those that
1172 we want to set to non-zero in ANTLOC. */
1174 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
1176 SET_BIT (antloc
[BLOCK_NUM (occr
->insn
)], indx
);
1178 /* While we're scanning the table, this is a good place to
1180 occr
->deleted_p
= 0;
1183 /* The occurrences recorded in avail_occr are exactly those that
1184 we want to set to non-zero in COMP. */
1186 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
1188 SET_BIT (comp
[BLOCK_NUM (occr
->insn
)], indx
);
1190 /* While we're scanning the table, this is a good place to
1195 /* While we're scanning the table, this is a good place to
1197 expr
->reaching_reg
= 0;
1202 /* Register set information.
1204 `reg_set_table' records where each register is set or otherwise
1207 static struct obstack reg_set_obstack
;
1210 alloc_reg_set_mem (n_regs
)
1215 reg_set_table_size
= n_regs
+ REG_SET_TABLE_SLOP
;
1216 n
= reg_set_table_size
* sizeof (struct reg_set
*);
1217 reg_set_table
= (struct reg_set
**) gmalloc (n
);
1218 memset ((char *) reg_set_table
, 0, n
);
1220 gcc_obstack_init (®_set_obstack
);
1226 free (reg_set_table
);
1227 obstack_free (®_set_obstack
, NULL
);
1230 /* Record REGNO in the reg_set table. */
1233 record_one_set (regno
, insn
)
1237 /* Allocate a new reg_set element and link it onto the list. */
1238 struct reg_set
*new_reg_info
;
1240 /* If the table isn't big enough, enlarge it. */
1241 if (regno
>= reg_set_table_size
)
1243 int new_size
= regno
+ REG_SET_TABLE_SLOP
;
1246 = (struct reg_set
**) grealloc ((char *) reg_set_table
,
1247 new_size
* sizeof (struct reg_set
*));
1248 memset ((char *) (reg_set_table
+ reg_set_table_size
), 0,
1249 (new_size
- reg_set_table_size
) * sizeof (struct reg_set
*));
1250 reg_set_table_size
= new_size
;
1253 new_reg_info
= (struct reg_set
*) obstack_alloc (®_set_obstack
,
1254 sizeof (struct reg_set
));
1255 bytes_used
+= sizeof (struct reg_set
);
1256 new_reg_info
->insn
= insn
;
1257 new_reg_info
->next
= reg_set_table
[regno
];
1258 reg_set_table
[regno
] = new_reg_info
;
1261 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1262 an insn. The DATA is really the instruction in which the SET is
1266 record_set_info (dest
, setter
, data
)
1267 rtx dest
, setter ATTRIBUTE_UNUSED
;
1270 rtx record_set_insn
= (rtx
) data
;
1272 if (GET_CODE (dest
) == REG
&& REGNO (dest
) >= FIRST_PSEUDO_REGISTER
)
1273 record_one_set (REGNO (dest
), record_set_insn
);
1276 /* Scan the function and record each set of each pseudo-register.
1278 This is called once, at the start of the gcse pass. See the comments for
1279 `reg_set_table' for further documenation. */
1287 for (insn
= f
; insn
!= 0; insn
= NEXT_INSN (insn
))
1289 note_stores (PATTERN (insn
), record_set_info
, insn
);
1292 /* Hash table support. */
1294 /* For each register, the cuid of the first/last insn in the block
1295 that set it, or -1 if not set. */
1296 #define NEVER_SET -1
1298 struct reg_avail_info
1300 basic_block last_bb
;
1305 static struct reg_avail_info
*reg_avail_info
;
1306 static basic_block current_bb
;
1309 /* See whether X, the source of a set, is something we want to consider for
1312 static GTY(()) rtx test_insn
;
1317 int num_clobbers
= 0;
1320 switch (GET_CODE (x
))
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 non-zero 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 (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 non-zero 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 non-zero 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 eliminatio 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 non-zero 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
))
1838 return INTVAL (x
) == INTVAL (y
);
1841 return XEXP (x
, 0) == XEXP (y
, 0);
1844 return XSTR (x
, 0) == XSTR (y
, 0);
1847 return REGNO (x
) == REGNO (y
);
1850 /* Can't merge two expressions in different alias sets, since we can
1851 decide that the expression is transparent in a block when it isn't,
1852 due to it being set with the different alias set. */
1853 if (MEM_ALIAS_SET (x
) != MEM_ALIAS_SET (y
))
1857 /* For commutative operations, check both orders. */
1865 return ((expr_equiv_p (XEXP (x
, 0), XEXP (y
, 0))
1866 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 1)))
1867 || (expr_equiv_p (XEXP (x
, 0), XEXP (y
, 1))
1868 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 0))));
1871 /* We don't use the generic code below because we want to
1872 disregard filename and line numbers. */
1874 /* A volatile asm isn't equivalent to any other. */
1875 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
1878 if (GET_MODE (x
) != GET_MODE (y
)
1879 || strcmp (ASM_OPERANDS_TEMPLATE (x
), ASM_OPERANDS_TEMPLATE (y
))
1880 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
),
1881 ASM_OPERANDS_OUTPUT_CONSTRAINT (y
))
1882 || ASM_OPERANDS_OUTPUT_IDX (x
) != ASM_OPERANDS_OUTPUT_IDX (y
)
1883 || ASM_OPERANDS_INPUT_LENGTH (x
) != ASM_OPERANDS_INPUT_LENGTH (y
))
1886 if (ASM_OPERANDS_INPUT_LENGTH (x
))
1888 for (i
= ASM_OPERANDS_INPUT_LENGTH (x
) - 1; i
>= 0; i
--)
1889 if (! expr_equiv_p (ASM_OPERANDS_INPUT (x
, i
),
1890 ASM_OPERANDS_INPUT (y
, i
))
1891 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x
, i
),
1892 ASM_OPERANDS_INPUT_CONSTRAINT (y
, i
)))
1902 /* Compare the elements. If any pair of corresponding elements
1903 fail to match, return 0 for the whole thing. */
1905 fmt
= GET_RTX_FORMAT (code
);
1906 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1911 if (! expr_equiv_p (XEXP (x
, i
), XEXP (y
, i
)))
1916 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1918 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1919 if (! expr_equiv_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
1924 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1929 if (XINT (x
, i
) != XINT (y
, i
))
1934 if (XWINT (x
, i
) != XWINT (y
, i
))
1949 /* Insert expression X in INSN in the hash table.
1950 If it is already present, record it as the last occurrence in INSN's
1953 MODE is the mode of the value X is being stored into.
1954 It is only used if X is a CONST_INT.
1956 ANTIC_P is non-zero if X is an anticipatable expression.
1957 AVAIL_P is non-zero if X is an available expression. */
1960 insert_expr_in_table (x
, mode
, insn
, antic_p
, avail_p
)
1962 enum machine_mode mode
;
1964 int antic_p
, avail_p
;
1966 int found
, do_not_record_p
;
1968 struct expr
*cur_expr
, *last_expr
= NULL
;
1969 struct occr
*antic_occr
, *avail_occr
;
1970 struct occr
*last_occr
= NULL
;
1972 hash
= hash_expr (x
, mode
, &do_not_record_p
, expr_hash_table_size
);
1974 /* Do not insert expression in table if it contains volatile operands,
1975 or if hash_expr determines the expression is something we don't want
1976 to or can't handle. */
1977 if (do_not_record_p
)
1980 cur_expr
= expr_hash_table
[hash
];
1983 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1985 /* If the expression isn't found, save a pointer to the end of
1987 last_expr
= cur_expr
;
1988 cur_expr
= cur_expr
->next_same_hash
;
1993 cur_expr
= (struct expr
*) gcse_alloc (sizeof (struct expr
));
1994 bytes_used
+= sizeof (struct expr
);
1995 if (expr_hash_table
[hash
] == NULL
)
1996 /* This is the first pattern that hashed to this index. */
1997 expr_hash_table
[hash
] = cur_expr
;
1999 /* Add EXPR to end of this hash chain. */
2000 last_expr
->next_same_hash
= cur_expr
;
2002 /* Set the fields of the expr element. */
2004 cur_expr
->bitmap_index
= n_exprs
++;
2005 cur_expr
->next_same_hash
= NULL
;
2006 cur_expr
->antic_occr
= NULL
;
2007 cur_expr
->avail_occr
= NULL
;
2010 /* Now record the occurrence(s). */
2013 antic_occr
= cur_expr
->antic_occr
;
2015 /* Search for another occurrence in the same basic block. */
2016 while (antic_occr
&& BLOCK_NUM (antic_occr
->insn
) != BLOCK_NUM (insn
))
2018 /* If an occurrence isn't found, save a pointer to the end of
2020 last_occr
= antic_occr
;
2021 antic_occr
= antic_occr
->next
;
2025 /* Found another instance of the expression in the same basic block.
2026 Prefer the currently recorded one. We want the first one in the
2027 block and the block is scanned from start to end. */
2028 ; /* nothing to do */
2031 /* First occurrence of this expression in this basic block. */
2032 antic_occr
= (struct occr
*) gcse_alloc (sizeof (struct occr
));
2033 bytes_used
+= sizeof (struct occr
);
2034 /* First occurrence of this expression in any block? */
2035 if (cur_expr
->antic_occr
== NULL
)
2036 cur_expr
->antic_occr
= antic_occr
;
2038 last_occr
->next
= antic_occr
;
2040 antic_occr
->insn
= insn
;
2041 antic_occr
->next
= NULL
;
2047 avail_occr
= cur_expr
->avail_occr
;
2049 /* Search for another occurrence in the same basic block. */
2050 while (avail_occr
&& BLOCK_NUM (avail_occr
->insn
) != BLOCK_NUM (insn
))
2052 /* If an occurrence isn't found, save a pointer to the end of
2054 last_occr
= avail_occr
;
2055 avail_occr
= avail_occr
->next
;
2059 /* Found another instance of the expression in the same basic block.
2060 Prefer this occurrence to the currently recorded one. We want
2061 the last one in the block and the block is scanned from start
2063 avail_occr
->insn
= insn
;
2066 /* First occurrence of this expression in this basic block. */
2067 avail_occr
= (struct occr
*) gcse_alloc (sizeof (struct occr
));
2068 bytes_used
+= sizeof (struct occr
);
2070 /* First occurrence of this expression in any block? */
2071 if (cur_expr
->avail_occr
== NULL
)
2072 cur_expr
->avail_occr
= avail_occr
;
2074 last_occr
->next
= avail_occr
;
2076 avail_occr
->insn
= insn
;
2077 avail_occr
->next
= NULL
;
2082 /* Insert pattern X in INSN in the hash table.
2083 X is a SET of a reg to either another reg or a constant.
2084 If it is already present, record it as the last occurrence in INSN's
2088 insert_set_in_table (x
, insn
)
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
)), set_hash_table_size
);
2103 cur_expr
= set_hash_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 (set_hash_table
[hash
] == NULL
)
2119 /* This is the first pattern that hashed to this index. */
2120 set_hash_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
= n_sets
++;
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 /* Scan pattern PAT of INSN and add an entry to the hash table. If SET_P is
2170 non-zero, this is for the assignment hash table, otherwise it is for the
2171 expression hash table. */
2174 hash_scan_set (pat
, insn
, set_p
)
2178 rtx src
= SET_SRC (pat
);
2179 rtx dest
= SET_DEST (pat
);
2182 if (GET_CODE (src
) == CALL
)
2183 hash_scan_call (src
, insn
);
2185 else if (GET_CODE (dest
) == REG
)
2187 unsigned int regno
= REGNO (dest
);
2190 /* If this is a single set and we are doing constant propagation,
2191 see if a REG_NOTE shows this equivalent to a constant. */
2192 if (set_p
&& (note
= find_reg_equal_equiv_note (insn
)) != 0
2193 && CONSTANT_P (XEXP (note
, 0)))
2194 src
= XEXP (note
, 0), pat
= gen_rtx_SET (VOIDmode
, dest
, src
);
2196 /* Only record sets of pseudo-regs in the hash table. */
2198 && regno
>= FIRST_PSEUDO_REGISTER
2199 /* Don't GCSE something if we can't do a reg/reg copy. */
2200 && can_copy_p
[GET_MODE (dest
)]
2201 /* GCSE commonly inserts instruction after the insn. We can't
2202 do that easily for EH_REGION notes so disable GCSE on these
2204 && !find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
2205 /* Is SET_SRC something we want to gcse? */
2206 && want_to_gcse_p (src
)
2207 /* Don't CSE a nop. */
2208 && ! set_noop_p (pat
)
2209 /* Don't GCSE if it has attached REG_EQUIV note.
2210 At this point this only function parameters should have
2211 REG_EQUIV notes and if the argument slot is used somewhere
2212 explicitly, it means address of parameter has been taken,
2213 so we should not extend the lifetime of the pseudo. */
2214 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
2215 || GET_CODE (XEXP (note
, 0)) != MEM
))
2217 /* An expression is not anticipatable if its operands are
2218 modified before this insn or if this is not the only SET in
2220 int antic_p
= oprs_anticipatable_p (src
, insn
) && single_set (insn
);
2221 /* An expression is not available if its operands are
2222 subsequently modified, including this insn. It's also not
2223 available if this is a branch, because we can't insert
2224 a set after the branch. */
2225 int avail_p
= (oprs_available_p (src
, insn
)
2226 && ! JUMP_P (insn
));
2228 insert_expr_in_table (src
, GET_MODE (dest
), insn
, antic_p
, avail_p
);
2231 /* Record sets for constant/copy propagation. */
2233 && regno
>= FIRST_PSEUDO_REGISTER
2234 && ((GET_CODE (src
) == REG
2235 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
2236 && can_copy_p
[GET_MODE (dest
)]
2237 && REGNO (src
) != regno
)
2238 || CONSTANT_P (src
))
2239 /* A copy is not available if its src or dest is subsequently
2240 modified. Here we want to search from INSN+1 on, but
2241 oprs_available_p searches from INSN on. */
2242 && (insn
== BLOCK_END (BLOCK_NUM (insn
))
2243 || ((tmp
= next_nonnote_insn (insn
)) != NULL_RTX
2244 && oprs_available_p (pat
, tmp
))))
2245 insert_set_in_table (pat
, insn
);
2250 hash_scan_clobber (x
, insn
)
2251 rtx x ATTRIBUTE_UNUSED
, insn ATTRIBUTE_UNUSED
;
2253 /* Currently nothing to do. */
2257 hash_scan_call (x
, insn
)
2258 rtx x ATTRIBUTE_UNUSED
, insn ATTRIBUTE_UNUSED
;
2260 /* Currently nothing to do. */
2263 /* Process INSN and add hash table entries as appropriate.
2265 Only available expressions that set a single pseudo-reg are recorded.
2267 Single sets in a PARALLEL could be handled, but it's an extra complication
2268 that isn't dealt with right now. The trick is handling the CLOBBERs that
2269 are also in the PARALLEL. Later.
2271 If SET_P is non-zero, this is for the assignment hash table,
2272 otherwise it is for the expression hash table.
2273 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
2274 not record any expressions. */
2277 hash_scan_insn (insn
, set_p
, in_libcall_block
)
2280 int in_libcall_block
;
2282 rtx pat
= PATTERN (insn
);
2285 if (in_libcall_block
)
2288 /* Pick out the sets of INSN and for other forms of instructions record
2289 what's been modified. */
2291 if (GET_CODE (pat
) == SET
)
2292 hash_scan_set (pat
, insn
, set_p
);
2293 else if (GET_CODE (pat
) == PARALLEL
)
2294 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2296 rtx x
= XVECEXP (pat
, 0, i
);
2298 if (GET_CODE (x
) == SET
)
2299 hash_scan_set (x
, insn
, set_p
);
2300 else if (GET_CODE (x
) == CLOBBER
)
2301 hash_scan_clobber (x
, insn
);
2302 else if (GET_CODE (x
) == CALL
)
2303 hash_scan_call (x
, insn
);
2306 else if (GET_CODE (pat
) == CLOBBER
)
2307 hash_scan_clobber (pat
, insn
);
2308 else if (GET_CODE (pat
) == CALL
)
2309 hash_scan_call (pat
, insn
);
2313 dump_hash_table (file
, name
, table
, table_size
, total_size
)
2316 struct expr
**table
;
2317 int table_size
, total_size
;
2320 /* Flattened out table, so it's printed in proper order. */
2321 struct expr
**flat_table
;
2322 unsigned int *hash_val
;
2326 = (struct expr
**) xcalloc (total_size
, sizeof (struct expr
*));
2327 hash_val
= (unsigned int *) xmalloc (total_size
* sizeof (unsigned int));
2329 for (i
= 0; i
< table_size
; i
++)
2330 for (expr
= table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
2332 flat_table
[expr
->bitmap_index
] = expr
;
2333 hash_val
[expr
->bitmap_index
] = i
;
2336 fprintf (file
, "%s hash table (%d buckets, %d entries)\n",
2337 name
, table_size
, total_size
);
2339 for (i
= 0; i
< total_size
; i
++)
2340 if (flat_table
[i
] != 0)
2342 expr
= flat_table
[i
];
2343 fprintf (file
, "Index %d (hash value %d)\n ",
2344 expr
->bitmap_index
, hash_val
[i
]);
2345 print_rtl (file
, expr
->expr
);
2346 fprintf (file
, "\n");
2349 fprintf (file
, "\n");
2355 /* Record register first/last/block set information for REGNO in INSN.
2357 first_set records the first place in the block where the register
2358 is set and is used to compute "anticipatability".
2360 last_set records the last place in the block where the register
2361 is set and is used to compute "availability".
2363 last_bb records the block for which first_set and last_set are
2364 valid, as a quick test to invalidate them.
2366 reg_set_in_block records whether the register is set in the block
2367 and is used to compute "transparency". */
2370 record_last_reg_set_info (insn
, regno
)
2374 struct reg_avail_info
*info
= ®_avail_info
[regno
];
2375 int cuid
= INSN_CUID (insn
);
2377 info
->last_set
= cuid
;
2378 if (info
->last_bb
!= current_bb
)
2380 info
->last_bb
= current_bb
;
2381 info
->first_set
= cuid
;
2382 SET_BIT (reg_set_in_block
[current_bb
->index
], regno
);
2387 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
2388 Note we store a pair of elements in the list, so they have to be
2389 taken off pairwise. */
2392 canon_list_insert (dest
, unused1
, v_insn
)
2393 rtx dest ATTRIBUTE_UNUSED
;
2394 rtx unused1 ATTRIBUTE_UNUSED
;
2397 rtx dest_addr
, insn
;
2400 while (GET_CODE (dest
) == SUBREG
2401 || GET_CODE (dest
) == ZERO_EXTRACT
2402 || GET_CODE (dest
) == SIGN_EXTRACT
2403 || GET_CODE (dest
) == STRICT_LOW_PART
)
2404 dest
= XEXP (dest
, 0);
2406 /* If DEST is not a MEM, then it will not conflict with a load. Note
2407 that function calls are assumed to clobber memory, but are handled
2410 if (GET_CODE (dest
) != MEM
)
2413 dest_addr
= get_addr (XEXP (dest
, 0));
2414 dest_addr
= canon_rtx (dest_addr
);
2415 insn
= (rtx
) v_insn
;
2416 bb
= BLOCK_NUM (insn
);
2418 canon_modify_mem_list
[bb
] =
2419 alloc_EXPR_LIST (VOIDmode
, dest_addr
, canon_modify_mem_list
[bb
]);
2420 canon_modify_mem_list
[bb
] =
2421 alloc_EXPR_LIST (VOIDmode
, dest
, canon_modify_mem_list
[bb
]);
2422 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2425 /* Record memory modification information for INSN. We do not actually care
2426 about the memory location(s) that are set, or even how they are set (consider
2427 a CALL_INSN). We merely need to record which insns modify memory. */
2430 record_last_mem_set_info (insn
)
2433 int bb
= BLOCK_NUM (insn
);
2435 /* load_killed_in_block_p will handle the case of calls clobbering
2437 modify_mem_list
[bb
] = alloc_INSN_LIST (insn
, modify_mem_list
[bb
]);
2438 bitmap_set_bit (modify_mem_list_set
, bb
);
2440 if (GET_CODE (insn
) == CALL_INSN
)
2442 /* Note that traversals of this loop (other than for free-ing)
2443 will break after encountering a CALL_INSN. So, there's no
2444 need to insert a pair of items, as canon_list_insert does. */
2445 canon_modify_mem_list
[bb
] =
2446 alloc_INSN_LIST (insn
, canon_modify_mem_list
[bb
]);
2447 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2450 note_stores (PATTERN (insn
), canon_list_insert
, (void*) insn
);
2453 /* Called from compute_hash_table via note_stores to handle one
2454 SET or CLOBBER in an insn. DATA is really the instruction in which
2455 the SET is taking place. */
2458 record_last_set_info (dest
, setter
, data
)
2459 rtx dest
, setter ATTRIBUTE_UNUSED
;
2462 rtx last_set_insn
= (rtx
) data
;
2464 if (GET_CODE (dest
) == SUBREG
)
2465 dest
= SUBREG_REG (dest
);
2467 if (GET_CODE (dest
) == REG
)
2468 record_last_reg_set_info (last_set_insn
, REGNO (dest
));
2469 else if (GET_CODE (dest
) == MEM
2470 /* Ignore pushes, they clobber nothing. */
2471 && ! push_operand (dest
, GET_MODE (dest
)))
2472 record_last_mem_set_info (last_set_insn
);
2475 /* Top level function to create an expression or assignment hash table.
2477 Expression entries are placed in the hash table if
2478 - they are of the form (set (pseudo-reg) src),
2479 - src is something we want to perform GCSE on,
2480 - none of the operands are subsequently modified in the block
2482 Assignment entries are placed in the hash table if
2483 - they are of the form (set (pseudo-reg) src),
2484 - src is something we want to perform const/copy propagation on,
2485 - none of the operands or target are subsequently modified in the block
2487 Currently src must be a pseudo-reg or a const_int.
2489 F is the first insn.
2490 SET_P is non-zero for computing the assignment hash table. */
2493 compute_hash_table (set_p
)
2498 /* While we compute the hash table we also compute a bit array of which
2499 registers are set in which blocks.
2500 ??? This isn't needed during const/copy propagation, but it's cheap to
2502 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
2504 /* re-Cache any INSN_LIST nodes we have allocated. */
2505 clear_modify_mem_tables ();
2506 /* Some working arrays used to track first and last set in each block. */
2507 reg_avail_info
= (struct reg_avail_info
*)
2508 gmalloc (max_gcse_regno
* sizeof (struct reg_avail_info
));
2510 for (i
= 0; i
< max_gcse_regno
; ++i
)
2511 reg_avail_info
[i
].last_bb
= NULL
;
2513 FOR_EACH_BB (current_bb
)
2517 int in_libcall_block
;
2519 /* First pass over the instructions records information used to
2520 determine when registers and memory are first and last set.
2521 ??? hard-reg reg_set_in_block computation
2522 could be moved to compute_sets since they currently don't change. */
2524 for (insn
= current_bb
->head
;
2525 insn
&& insn
!= NEXT_INSN (current_bb
->end
);
2526 insn
= NEXT_INSN (insn
))
2528 if (! INSN_P (insn
))
2531 if (GET_CODE (insn
) == CALL_INSN
)
2533 bool clobbers_all
= false;
2534 #ifdef NON_SAVING_SETJMP
2535 if (NON_SAVING_SETJMP
2536 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
2537 clobbers_all
= true;
2540 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2542 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2543 record_last_reg_set_info (insn
, regno
);
2548 note_stores (PATTERN (insn
), record_last_set_info
, insn
);
2551 /* The next pass builds the hash table. */
2553 for (insn
= current_bb
->head
, in_libcall_block
= 0;
2554 insn
&& insn
!= NEXT_INSN (current_bb
->end
);
2555 insn
= NEXT_INSN (insn
))
2558 if (find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2559 in_libcall_block
= 1;
2560 else if (set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2561 in_libcall_block
= 0;
2562 hash_scan_insn (insn
, set_p
, in_libcall_block
);
2563 if (!set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2564 in_libcall_block
= 0;
2568 free (reg_avail_info
);
2569 reg_avail_info
= NULL
;
2572 /* Allocate space for the set hash table.
2573 N_INSNS is the number of instructions in the function.
2574 It is used to determine the number of buckets to use. */
2577 alloc_set_hash_table (n_insns
)
2582 set_hash_table_size
= n_insns
/ 4;
2583 if (set_hash_table_size
< 11)
2584 set_hash_table_size
= 11;
2586 /* Attempt to maintain efficient use of hash table.
2587 Making it an odd number is simplest for now.
2588 ??? Later take some measurements. */
2589 set_hash_table_size
|= 1;
2590 n
= set_hash_table_size
* sizeof (struct expr
*);
2591 set_hash_table
= (struct expr
**) gmalloc (n
);
2594 /* Free things allocated by alloc_set_hash_table. */
2597 free_set_hash_table ()
2599 free (set_hash_table
);
2602 /* Compute the hash table for doing copy/const propagation. */
2605 compute_set_hash_table ()
2607 /* Initialize count of number of entries in hash table. */
2609 memset ((char *) set_hash_table
, 0,
2610 set_hash_table_size
* sizeof (struct expr
*));
2612 compute_hash_table (1);
2615 /* Allocate space for the expression hash table.
2616 N_INSNS is the number of instructions in the function.
2617 It is used to determine the number of buckets to use. */
2620 alloc_expr_hash_table (n_insns
)
2621 unsigned int n_insns
;
2625 expr_hash_table_size
= n_insns
/ 2;
2626 /* Make sure the amount is usable. */
2627 if (expr_hash_table_size
< 11)
2628 expr_hash_table_size
= 11;
2630 /* Attempt to maintain efficient use of hash table.
2631 Making it an odd number is simplest for now.
2632 ??? Later take some measurements. */
2633 expr_hash_table_size
|= 1;
2634 n
= expr_hash_table_size
* sizeof (struct expr
*);
2635 expr_hash_table
= (struct expr
**) gmalloc (n
);
2638 /* Free things allocated by alloc_expr_hash_table. */
2641 free_expr_hash_table ()
2643 free (expr_hash_table
);
2646 /* Compute the hash table for doing GCSE. */
2649 compute_expr_hash_table ()
2651 /* Initialize count of number of entries in hash table. */
2653 memset ((char *) expr_hash_table
, 0,
2654 expr_hash_table_size
* sizeof (struct expr
*));
2656 compute_hash_table (0);
2659 /* Expression tracking support. */
2661 /* Lookup pattern PAT in the expression table.
2662 The result is a pointer to the table entry, or NULL if not found. */
2664 static struct expr
*
2668 int do_not_record_p
;
2669 unsigned int hash
= hash_expr (pat
, GET_MODE (pat
), &do_not_record_p
,
2670 expr_hash_table_size
);
2673 if (do_not_record_p
)
2676 expr
= expr_hash_table
[hash
];
2678 while (expr
&& ! expr_equiv_p (expr
->expr
, pat
))
2679 expr
= expr
->next_same_hash
;
2684 /* Lookup REGNO in the set table. If PAT is non-NULL look for the entry that
2685 matches it, otherwise return the first entry for REGNO. The result is a
2686 pointer to the table entry, or NULL if not found. */
2688 static struct expr
*
2689 lookup_set (regno
, pat
)
2693 unsigned int hash
= hash_set (regno
, set_hash_table_size
);
2696 expr
= set_hash_table
[hash
];
2700 while (expr
&& ! expr_equiv_p (expr
->expr
, pat
))
2701 expr
= expr
->next_same_hash
;
2705 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
)
2706 expr
= expr
->next_same_hash
;
2712 /* Return the next entry for REGNO in list EXPR. */
2714 static struct expr
*
2715 next_set (regno
, expr
)
2720 expr
= expr
->next_same_hash
;
2721 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
);
2726 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2727 types may be mixed. */
2730 free_insn_expr_list_list (listp
)
2735 for (list
= *listp
; list
; list
= next
)
2737 next
= XEXP (list
, 1);
2738 if (GET_CODE (list
) == EXPR_LIST
)
2739 free_EXPR_LIST_node (list
);
2741 free_INSN_LIST_node (list
);
2747 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2749 clear_modify_mem_tables ()
2753 EXECUTE_IF_SET_IN_BITMAP
2754 (modify_mem_list_set
, 0, i
, free_INSN_LIST_list (modify_mem_list
+ i
));
2755 bitmap_clear (modify_mem_list_set
);
2757 EXECUTE_IF_SET_IN_BITMAP
2758 (canon_modify_mem_list_set
, 0, i
,
2759 free_insn_expr_list_list (canon_modify_mem_list
+ i
));
2760 bitmap_clear (canon_modify_mem_list_set
);
2763 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2766 free_modify_mem_tables ()
2768 clear_modify_mem_tables ();
2769 free (modify_mem_list
);
2770 free (canon_modify_mem_list
);
2771 modify_mem_list
= 0;
2772 canon_modify_mem_list
= 0;
2775 /* Reset tables used to keep track of what's still available [since the
2776 start of the block]. */
2779 reset_opr_set_tables ()
2781 /* Maintain a bitmap of which regs have been set since beginning of
2783 CLEAR_REG_SET (reg_set_bitmap
);
2785 /* Also keep a record of the last instruction to modify memory.
2786 For now this is very trivial, we only record whether any memory
2787 location has been modified. */
2788 clear_modify_mem_tables ();
2791 /* Return non-zero if the operands of X are not set before INSN in
2792 INSN's basic block. */
2795 oprs_not_set_p (x
, insn
)
2805 code
= GET_CODE (x
);
2821 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn
),
2822 INSN_CUID (insn
), x
, 0))
2825 return oprs_not_set_p (XEXP (x
, 0), insn
);
2828 return ! REGNO_REG_SET_P (reg_set_bitmap
, REGNO (x
));
2834 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2838 /* If we are about to do the last recursive call
2839 needed at this level, change it into iteration.
2840 This function is called enough to be worth it. */
2842 return oprs_not_set_p (XEXP (x
, i
), insn
);
2844 if (! oprs_not_set_p (XEXP (x
, i
), insn
))
2847 else if (fmt
[i
] == 'E')
2848 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2849 if (! oprs_not_set_p (XVECEXP (x
, i
, j
), insn
))
2856 /* Mark things set by a CALL. */
2862 if (! CONST_OR_PURE_CALL_P (insn
))
2863 record_last_mem_set_info (insn
);
2866 /* Mark things set by a SET. */
2869 mark_set (pat
, insn
)
2872 rtx dest
= SET_DEST (pat
);
2874 while (GET_CODE (dest
) == SUBREG
2875 || GET_CODE (dest
) == ZERO_EXTRACT
2876 || GET_CODE (dest
) == SIGN_EXTRACT
2877 || GET_CODE (dest
) == STRICT_LOW_PART
)
2878 dest
= XEXP (dest
, 0);
2880 if (GET_CODE (dest
) == REG
)
2881 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (dest
));
2882 else if (GET_CODE (dest
) == MEM
)
2883 record_last_mem_set_info (insn
);
2885 if (GET_CODE (SET_SRC (pat
)) == CALL
)
2889 /* Record things set by a CLOBBER. */
2892 mark_clobber (pat
, insn
)
2895 rtx clob
= XEXP (pat
, 0);
2897 while (GET_CODE (clob
) == SUBREG
|| GET_CODE (clob
) == STRICT_LOW_PART
)
2898 clob
= XEXP (clob
, 0);
2900 if (GET_CODE (clob
) == REG
)
2901 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (clob
));
2903 record_last_mem_set_info (insn
);
2906 /* Record things set by INSN.
2907 This data is used by oprs_not_set_p. */
2910 mark_oprs_set (insn
)
2913 rtx pat
= PATTERN (insn
);
2916 if (GET_CODE (pat
) == SET
)
2917 mark_set (pat
, insn
);
2918 else if (GET_CODE (pat
) == PARALLEL
)
2919 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2921 rtx x
= XVECEXP (pat
, 0, i
);
2923 if (GET_CODE (x
) == SET
)
2925 else if (GET_CODE (x
) == CLOBBER
)
2926 mark_clobber (x
, insn
);
2927 else if (GET_CODE (x
) == CALL
)
2931 else if (GET_CODE (pat
) == CLOBBER
)
2932 mark_clobber (pat
, insn
);
2933 else if (GET_CODE (pat
) == CALL
)
2938 /* Classic GCSE reaching definition support. */
2940 /* Allocate reaching def variables. */
2943 alloc_rd_mem (n_blocks
, n_insns
)
2944 int n_blocks
, n_insns
;
2946 rd_kill
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2947 sbitmap_vector_zero (rd_kill
, n_blocks
);
2949 rd_gen
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2950 sbitmap_vector_zero (rd_gen
, n_blocks
);
2952 reaching_defs
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2953 sbitmap_vector_zero (reaching_defs
, n_blocks
);
2955 rd_out
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2956 sbitmap_vector_zero (rd_out
, n_blocks
);
2959 /* Free reaching def variables. */
2964 sbitmap_vector_free (rd_kill
);
2965 sbitmap_vector_free (rd_gen
);
2966 sbitmap_vector_free (reaching_defs
);
2967 sbitmap_vector_free (rd_out
);
2970 /* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
2973 handle_rd_kill_set (insn
, regno
, bb
)
2978 struct reg_set
*this_reg
;
2980 for (this_reg
= reg_set_table
[regno
]; this_reg
; this_reg
= this_reg
->next
)
2981 if (BLOCK_NUM (this_reg
->insn
) != BLOCK_NUM (insn
))
2982 SET_BIT (rd_kill
[bb
->index
], INSN_CUID (this_reg
->insn
));
2985 /* Compute the set of kill's for reaching definitions. */
2996 For each set bit in `gen' of the block (i.e each insn which
2997 generates a definition in the block)
2998 Call the reg set by the insn corresponding to that bit regx
2999 Look at the linked list starting at reg_set_table[regx]
3000 For each setting of regx in the linked list, which is not in
3002 Set the bit in `kill' corresponding to that insn. */
3004 for (cuid
= 0; cuid
< max_cuid
; cuid
++)
3005 if (TEST_BIT (rd_gen
[bb
->index
], cuid
))
3007 rtx insn
= CUID_INSN (cuid
);
3008 rtx pat
= PATTERN (insn
);
3010 if (GET_CODE (insn
) == CALL_INSN
)
3012 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
3013 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
3014 handle_rd_kill_set (insn
, regno
, bb
);
3017 if (GET_CODE (pat
) == PARALLEL
)
3019 for (i
= XVECLEN (pat
, 0) - 1; i
>= 0; i
--)
3021 enum rtx_code code
= GET_CODE (XVECEXP (pat
, 0, i
));
3023 if ((code
== SET
|| code
== CLOBBER
)
3024 && GET_CODE (XEXP (XVECEXP (pat
, 0, i
), 0)) == REG
)
3025 handle_rd_kill_set (insn
,
3026 REGNO (XEXP (XVECEXP (pat
, 0, i
), 0)),
3030 else if (GET_CODE (pat
) == SET
&& GET_CODE (SET_DEST (pat
)) == REG
)
3031 /* Each setting of this register outside of this block
3032 must be marked in the set of kills in this block. */
3033 handle_rd_kill_set (insn
, REGNO (SET_DEST (pat
)), bb
);
3037 /* Compute the reaching definitions as in
3038 Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
3039 Chapter 10. It is the same algorithm as used for computing available
3040 expressions but applied to the gens and kills of reaching definitions. */
3045 int changed
, passes
;
3049 sbitmap_copy (rd_out
[bb
->index
] /*dst*/, rd_gen
[bb
->index
] /*src*/);
3058 sbitmap_union_of_preds (reaching_defs
[bb
->index
], rd_out
, bb
->index
);
3059 changed
|= sbitmap_union_of_diff_cg (rd_out
[bb
->index
], rd_gen
[bb
->index
],
3060 reaching_defs
[bb
->index
], rd_kill
[bb
->index
]);
3066 fprintf (gcse_file
, "reaching def computation: %d passes\n", passes
);
3069 /* Classic GCSE available expression support. */
3071 /* Allocate memory for available expression computation. */
3074 alloc_avail_expr_mem (n_blocks
, n_exprs
)
3075 int n_blocks
, n_exprs
;
3077 ae_kill
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3078 sbitmap_vector_zero (ae_kill
, n_blocks
);
3080 ae_gen
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3081 sbitmap_vector_zero (ae_gen
, n_blocks
);
3083 ae_in
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3084 sbitmap_vector_zero (ae_in
, n_blocks
);
3086 ae_out
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3087 sbitmap_vector_zero (ae_out
, n_blocks
);
3091 free_avail_expr_mem ()
3093 sbitmap_vector_free (ae_kill
);
3094 sbitmap_vector_free (ae_gen
);
3095 sbitmap_vector_free (ae_in
);
3096 sbitmap_vector_free (ae_out
);
3099 /* Compute the set of available expressions generated in each basic block. */
3108 /* For each recorded occurrence of each expression, set ae_gen[bb][expr].
3109 This is all we have to do because an expression is not recorded if it
3110 is not available, and the only expressions we want to work with are the
3111 ones that are recorded. */
3112 for (i
= 0; i
< expr_hash_table_size
; i
++)
3113 for (expr
= expr_hash_table
[i
]; expr
!= 0; expr
= expr
->next_same_hash
)
3114 for (occr
= expr
->avail_occr
; occr
!= 0; occr
= occr
->next
)
3115 SET_BIT (ae_gen
[BLOCK_NUM (occr
->insn
)], expr
->bitmap_index
);
3118 /* Return non-zero if expression X is killed in BB. */
3121 expr_killed_p (x
, bb
)
3132 code
= GET_CODE (x
);
3136 return TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
));
3139 if (load_killed_in_block_p (bb
, get_max_uid () + 1, x
, 0))
3142 return expr_killed_p (XEXP (x
, 0), bb
);
3160 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3164 /* If we are about to do the last recursive call
3165 needed at this level, change it into iteration.
3166 This function is called enough to be worth it. */
3168 return expr_killed_p (XEXP (x
, i
), bb
);
3169 else if (expr_killed_p (XEXP (x
, i
), bb
))
3172 else if (fmt
[i
] == 'E')
3173 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3174 if (expr_killed_p (XVECEXP (x
, i
, j
), bb
))
3181 /* Compute the set of available expressions killed in each basic block. */
3184 compute_ae_kill (ae_gen
, ae_kill
)
3185 sbitmap
*ae_gen
, *ae_kill
;
3192 for (i
= 0; i
< expr_hash_table_size
; i
++)
3193 for (expr
= expr_hash_table
[i
]; expr
; expr
= expr
->next_same_hash
)
3195 /* Skip EXPR if generated in this block. */
3196 if (TEST_BIT (ae_gen
[bb
->index
], expr
->bitmap_index
))
3199 if (expr_killed_p (expr
->expr
, bb
))
3200 SET_BIT (ae_kill
[bb
->index
], expr
->bitmap_index
);
3204 /* Actually perform the Classic GCSE optimizations. */
3206 /* Return non-zero if occurrence OCCR of expression EXPR reaches block BB.
3208 CHECK_SELF_LOOP is non-zero if we should consider a block reaching itself
3209 as a positive reach. We want to do this when there are two computations
3210 of the expression in the block.
3212 VISITED is a pointer to a working buffer for tracking which BB's have
3213 been visited. It is NULL for the top-level call.
3215 We treat reaching expressions that go through blocks containing the same
3216 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3217 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3218 2 as not reaching. The intent is to improve the probability of finding
3219 only one reaching expression and to reduce register lifetimes by picking
3220 the closest such expression. */
3223 expr_reaches_here_p_work (occr
, expr
, bb
, check_self_loop
, visited
)
3227 int check_self_loop
;
3232 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
3234 basic_block pred_bb
= pred
->src
;
3236 if (visited
[pred_bb
->index
])
3237 /* This predecessor has already been visited. Nothing to do. */
3239 else if (pred_bb
== bb
)
3241 /* BB loops on itself. */
3243 && TEST_BIT (ae_gen
[pred_bb
->index
], expr
->bitmap_index
)
3244 && BLOCK_NUM (occr
->insn
) == pred_bb
->index
)
3247 visited
[pred_bb
->index
] = 1;
3250 /* Ignore this predecessor if it kills the expression. */
3251 else if (TEST_BIT (ae_kill
[pred_bb
->index
], expr
->bitmap_index
))
3252 visited
[pred_bb
->index
] = 1;
3254 /* Does this predecessor generate this expression? */
3255 else if (TEST_BIT (ae_gen
[pred_bb
->index
], expr
->bitmap_index
))
3257 /* Is this the occurrence we're looking for?
3258 Note that there's only one generating occurrence per block
3259 so we just need to check the block number. */
3260 if (BLOCK_NUM (occr
->insn
) == pred_bb
->index
)
3263 visited
[pred_bb
->index
] = 1;
3266 /* Neither gen nor kill. */
3269 visited
[pred_bb
->index
] = 1;
3270 if (expr_reaches_here_p_work (occr
, expr
, pred_bb
, check_self_loop
,
3277 /* All paths have been checked. */
3281 /* This wrapper for expr_reaches_here_p_work() is to ensure that any
3282 memory allocated for that function is returned. */
3285 expr_reaches_here_p (occr
, expr
, bb
, check_self_loop
)
3289 int check_self_loop
;
3292 char *visited
= (char *) xcalloc (last_basic_block
, 1);
3294 rval
= expr_reaches_here_p_work (occr
, expr
, bb
, check_self_loop
, visited
);
3300 /* Return the instruction that computes EXPR that reaches INSN's basic block.
3301 If there is more than one such instruction, return NULL.
3303 Called only by handle_avail_expr. */
3306 computing_insn (expr
, insn
)
3310 basic_block bb
= BLOCK_FOR_INSN (insn
);
3312 if (expr
->avail_occr
->next
== NULL
)
3314 if (BLOCK_FOR_INSN (expr
->avail_occr
->insn
) == bb
)
3315 /* The available expression is actually itself
3316 (i.e. a loop in the flow graph) so do nothing. */
3319 /* (FIXME) Case that we found a pattern that was created by
3320 a substitution that took place. */
3321 return expr
->avail_occr
->insn
;
3325 /* Pattern is computed more than once.
3326 Search backwards from this insn to see how many of these
3327 computations actually reach this insn. */
3329 rtx insn_computes_expr
= NULL
;
3332 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
3334 if (BLOCK_FOR_INSN (occr
->insn
) == bb
)
3336 /* The expression is generated in this block.
3337 The only time we care about this is when the expression
3338 is generated later in the block [and thus there's a loop].
3339 We let the normal cse pass handle the other cases. */
3340 if (INSN_CUID (insn
) < INSN_CUID (occr
->insn
)
3341 && expr_reaches_here_p (occr
, expr
, bb
, 1))
3347 insn_computes_expr
= occr
->insn
;
3350 else if (expr_reaches_here_p (occr
, expr
, bb
, 0))
3356 insn_computes_expr
= occr
->insn
;
3360 if (insn_computes_expr
== NULL
)
3363 return insn_computes_expr
;
3367 /* Return non-zero if the definition in DEF_INSN can reach INSN.
3368 Only called by can_disregard_other_sets. */
3371 def_reaches_here_p (insn
, def_insn
)
3376 if (TEST_BIT (reaching_defs
[BLOCK_NUM (insn
)], INSN_CUID (def_insn
)))
3379 if (BLOCK_NUM (insn
) == BLOCK_NUM (def_insn
))
3381 if (INSN_CUID (def_insn
) < INSN_CUID (insn
))
3383 if (GET_CODE (PATTERN (def_insn
)) == PARALLEL
)
3385 else if (GET_CODE (PATTERN (def_insn
)) == CLOBBER
)
3386 reg
= XEXP (PATTERN (def_insn
), 0);
3387 else if (GET_CODE (PATTERN (def_insn
)) == SET
)
3388 reg
= SET_DEST (PATTERN (def_insn
));
3392 return ! reg_set_between_p (reg
, NEXT_INSN (def_insn
), insn
);
3401 /* Return non-zero if *ADDR_THIS_REG can only have one value at INSN. The
3402 value returned is the number of definitions that reach INSN. Returning a
3403 value of zero means that [maybe] more than one definition reaches INSN and
3404 the caller can't perform whatever optimization it is trying. i.e. it is
3405 always safe to return zero. */
3408 can_disregard_other_sets (addr_this_reg
, insn
, for_combine
)
3409 struct reg_set
**addr_this_reg
;
3413 int number_of_reaching_defs
= 0;
3414 struct reg_set
*this_reg
;
3416 for (this_reg
= *addr_this_reg
; this_reg
!= 0; this_reg
= this_reg
->next
)
3417 if (def_reaches_here_p (insn
, this_reg
->insn
))
3419 number_of_reaching_defs
++;
3420 /* Ignore parallels for now. */
3421 if (GET_CODE (PATTERN (this_reg
->insn
)) == PARALLEL
)
3425 && (GET_CODE (PATTERN (this_reg
->insn
)) == CLOBBER
3426 || ! rtx_equal_p (SET_SRC (PATTERN (this_reg
->insn
)),
3427 SET_SRC (PATTERN (insn
)))))
3428 /* A setting of the reg to a different value reaches INSN. */
3431 if (number_of_reaching_defs
> 1)
3433 /* If in this setting the value the register is being set to is
3434 equal to the previous value the register was set to and this
3435 setting reaches the insn we are trying to do the substitution
3436 on then we are ok. */
3437 if (GET_CODE (PATTERN (this_reg
->insn
)) == CLOBBER
)
3439 else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg
->insn
)),
3440 SET_SRC (PATTERN (insn
))))
3444 *addr_this_reg
= this_reg
;
3447 return number_of_reaching_defs
;
3450 /* Expression computed by insn is available and the substitution is legal,
3451 so try to perform the substitution.
3453 The result is non-zero if any changes were made. */
3456 handle_avail_expr (insn
, expr
)
3460 rtx pat
, insn_computes_expr
, expr_set
;
3462 struct reg_set
*this_reg
;
3463 int found_setting
, use_src
;
3466 /* We only handle the case where one computation of the expression
3467 reaches this instruction. */
3468 insn_computes_expr
= computing_insn (expr
, insn
);
3469 if (insn_computes_expr
== NULL
)
3471 expr_set
= single_set (insn_computes_expr
);
3478 /* At this point we know only one computation of EXPR outside of this
3479 block reaches this insn. Now try to find a register that the
3480 expression is computed into. */
3481 if (GET_CODE (SET_SRC (expr_set
)) == REG
)
3483 /* This is the case when the available expression that reaches
3484 here has already been handled as an available expression. */
3485 unsigned int regnum_for_replacing
3486 = REGNO (SET_SRC (expr_set
));
3488 /* If the register was created by GCSE we can't use `reg_set_table',
3489 however we know it's set only once. */
3490 if (regnum_for_replacing
>= max_gcse_regno
3491 /* If the register the expression is computed into is set only once,
3492 or only one set reaches this insn, we can use it. */
3493 || (((this_reg
= reg_set_table
[regnum_for_replacing
]),
3494 this_reg
->next
== NULL
)
3495 || can_disregard_other_sets (&this_reg
, insn
, 0)))
3504 unsigned int regnum_for_replacing
3505 = REGNO (SET_DEST (expr_set
));
3507 /* This shouldn't happen. */
3508 if (regnum_for_replacing
>= max_gcse_regno
)
3511 this_reg
= reg_set_table
[regnum_for_replacing
];
3513 /* If the register the expression is computed into is set only once,
3514 or only one set reaches this insn, use it. */
3515 if (this_reg
->next
== NULL
3516 || can_disregard_other_sets (&this_reg
, insn
, 0))
3522 pat
= PATTERN (insn
);
3524 to
= SET_SRC (expr_set
);
3526 to
= SET_DEST (expr_set
);
3527 changed
= validate_change (insn
, &SET_SRC (pat
), to
, 0);
3529 /* We should be able to ignore the return code from validate_change but
3530 to play it safe we check. */
3534 if (gcse_file
!= NULL
)
3536 fprintf (gcse_file
, "GCSE: Replacing the source in insn %d with",
3538 fprintf (gcse_file
, " reg %d %s insn %d\n",
3539 REGNO (to
), use_src
? "from" : "set in",
3540 INSN_UID (insn_computes_expr
));
3545 /* The register that the expr is computed into is set more than once. */
3546 else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
3548 /* Insert an insn after insnx that copies the reg set in insnx
3549 into a new pseudo register call this new register REGN.
3550 From insnb until end of basic block or until REGB is set
3551 replace all uses of REGB with REGN. */
3554 to
= gen_reg_rtx (GET_MODE (SET_DEST (expr_set
)));
3556 /* Generate the new insn. */
3557 /* ??? If the change fails, we return 0, even though we created
3558 an insn. I think this is ok. */
3560 = emit_insn_after (gen_rtx_SET (VOIDmode
, to
,
3561 SET_DEST (expr_set
)),
3562 insn_computes_expr
);
3564 /* Keep register set table up to date. */
3565 record_one_set (REGNO (to
), new_insn
);
3567 gcse_create_count
++;
3568 if (gcse_file
!= NULL
)
3570 fprintf (gcse_file
, "GCSE: Creating insn %d to copy value of reg %d",
3571 INSN_UID (NEXT_INSN (insn_computes_expr
)),
3572 REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr
)))));
3573 fprintf (gcse_file
, ", computed in insn %d,\n",
3574 INSN_UID (insn_computes_expr
));
3575 fprintf (gcse_file
, " into newly allocated reg %d\n",
3579 pat
= PATTERN (insn
);
3581 /* Do register replacement for INSN. */
3582 changed
= validate_change (insn
, &SET_SRC (pat
),
3584 (NEXT_INSN (insn_computes_expr
))),
3587 /* We should be able to ignore the return code from validate_change but
3588 to play it safe we check. */
3592 if (gcse_file
!= NULL
)
3595 "GCSE: Replacing the source in insn %d with reg %d ",
3597 REGNO (SET_DEST (PATTERN (NEXT_INSN
3598 (insn_computes_expr
)))));
3599 fprintf (gcse_file
, "set in insn %d\n",
3600 INSN_UID (insn_computes_expr
));
3608 /* Perform classic GCSE. This is called by one_classic_gcse_pass after all
3609 the dataflow analysis has been done.
3611 The result is non-zero if a change was made. */
3620 /* Note we start at block 1. */
3622 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3626 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
3628 /* Reset tables used to keep track of what's still valid [since the
3629 start of the block]. */
3630 reset_opr_set_tables ();
3632 for (insn
= bb
->head
;
3633 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
3634 insn
= NEXT_INSN (insn
))
3636 /* Is insn of form (set (pseudo-reg) ...)? */
3637 if (GET_CODE (insn
) == INSN
3638 && GET_CODE (PATTERN (insn
)) == SET
3639 && GET_CODE (SET_DEST (PATTERN (insn
))) == REG
3640 && REGNO (SET_DEST (PATTERN (insn
))) >= FIRST_PSEUDO_REGISTER
)
3642 rtx pat
= PATTERN (insn
);
3643 rtx src
= SET_SRC (pat
);
3646 if (want_to_gcse_p (src
)
3647 /* Is the expression recorded? */
3648 && ((expr
= lookup_expr (src
)) != NULL
)
3649 /* Is the expression available [at the start of the
3651 && TEST_BIT (ae_in
[bb
->index
], expr
->bitmap_index
)
3652 /* Are the operands unchanged since the start of the
3654 && oprs_not_set_p (src
, insn
))
3655 changed
|= handle_avail_expr (insn
, expr
);
3658 /* Keep track of everything modified by this insn. */
3659 /* ??? Need to be careful w.r.t. mods done to INSN. */
3661 mark_oprs_set (insn
);
3668 /* Top level routine to perform one classic GCSE pass.
3670 Return non-zero if a change was made. */
3673 one_classic_gcse_pass (pass
)
3678 gcse_subst_count
= 0;
3679 gcse_create_count
= 0;
3681 alloc_expr_hash_table (max_cuid
);
3682 alloc_rd_mem (last_basic_block
, max_cuid
);
3683 compute_expr_hash_table ();
3685 dump_hash_table (gcse_file
, "Expression", expr_hash_table
,
3686 expr_hash_table_size
, n_exprs
);
3692 alloc_avail_expr_mem (last_basic_block
, n_exprs
);
3694 compute_ae_kill (ae_gen
, ae_kill
);
3695 compute_available (ae_gen
, ae_kill
, ae_out
, ae_in
);
3696 changed
= classic_gcse ();
3697 free_avail_expr_mem ();
3701 free_expr_hash_table ();
3705 fprintf (gcse_file
, "\n");
3706 fprintf (gcse_file
, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
3707 current_function_name
, pass
, bytes_used
, gcse_subst_count
);
3708 fprintf (gcse_file
, "%d insns created\n", gcse_create_count
);
3714 /* Compute copy/constant propagation working variables. */
3716 /* Local properties of assignments. */
3717 static sbitmap
*cprop_pavloc
;
3718 static sbitmap
*cprop_absaltered
;
3720 /* Global properties of assignments (computed from the local properties). */
3721 static sbitmap
*cprop_avin
;
3722 static sbitmap
*cprop_avout
;
3724 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
3725 basic blocks. N_SETS is the number of sets. */
3728 alloc_cprop_mem (n_blocks
, n_sets
)
3729 int n_blocks
, n_sets
;
3731 cprop_pavloc
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3732 cprop_absaltered
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3734 cprop_avin
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3735 cprop_avout
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3738 /* Free vars used by copy/const propagation. */
3743 sbitmap_vector_free (cprop_pavloc
);
3744 sbitmap_vector_free (cprop_absaltered
);
3745 sbitmap_vector_free (cprop_avin
);
3746 sbitmap_vector_free (cprop_avout
);
3749 /* For each block, compute whether X is transparent. X is either an
3750 expression or an assignment [though we don't care which, for this context
3751 an assignment is treated as an expression]. For each block where an
3752 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
3756 compute_transp (x
, indx
, bmap
, set_p
)
3768 /* repeat is used to turn tail-recursion into iteration since GCC
3769 can't do it when there's no return value. */
3775 code
= GET_CODE (x
);
3781 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
3784 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
3785 SET_BIT (bmap
[bb
->index
], indx
);
3789 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
3790 SET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
3795 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
3798 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
3799 RESET_BIT (bmap
[bb
->index
], indx
);
3803 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
3804 RESET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
3813 rtx list_entry
= canon_modify_mem_list
[bb
->index
];
3817 rtx dest
, dest_addr
;
3819 if (GET_CODE (XEXP (list_entry
, 0)) == CALL_INSN
)
3822 SET_BIT (bmap
[bb
->index
], indx
);
3824 RESET_BIT (bmap
[bb
->index
], indx
);
3827 /* LIST_ENTRY must be an INSN of some kind that sets memory.
3828 Examine each hunk of memory that is modified. */
3830 dest
= XEXP (list_entry
, 0);
3831 list_entry
= XEXP (list_entry
, 1);
3832 dest_addr
= XEXP (list_entry
, 0);
3834 if (canon_true_dependence (dest
, GET_MODE (dest
), dest_addr
,
3835 x
, rtx_addr_varies_p
))
3838 SET_BIT (bmap
[bb
->index
], indx
);
3840 RESET_BIT (bmap
[bb
->index
], indx
);
3843 list_entry
= XEXP (list_entry
, 1);
3866 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3870 /* If we are about to do the last recursive call
3871 needed at this level, change it into iteration.
3872 This function is called enough to be worth it. */
3879 compute_transp (XEXP (x
, i
), indx
, bmap
, set_p
);
3881 else if (fmt
[i
] == 'E')
3882 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3883 compute_transp (XVECEXP (x
, i
, j
), indx
, bmap
, set_p
);
3887 /* Top level routine to do the dataflow analysis needed by copy/const
3891 compute_cprop_data ()
3893 compute_local_properties (cprop_absaltered
, cprop_pavloc
, NULL
, 1);
3894 compute_available (cprop_pavloc
, cprop_absaltered
,
3895 cprop_avout
, cprop_avin
);
3898 /* Copy/constant propagation. */
3900 /* Maximum number of register uses in an insn that we handle. */
3903 /* Table of uses found in an insn.
3904 Allocated statically to avoid alloc/free complexity and overhead. */
3905 static struct reg_use reg_use_table
[MAX_USES
];
3907 /* Index into `reg_use_table' while building it. */
3908 static int reg_use_count
;
3910 /* Set up a list of register numbers used in INSN. The found uses are stored
3911 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
3912 and contains the number of uses in the table upon exit.
3914 ??? If a register appears multiple times we will record it multiple times.
3915 This doesn't hurt anything but it will slow things down. */
3918 find_used_regs (xptr
, data
)
3920 void *data ATTRIBUTE_UNUSED
;
3927 /* repeat is used to turn tail-recursion into iteration since GCC
3928 can't do it when there's no return value. */
3933 code
= GET_CODE (x
);
3936 if (reg_use_count
== MAX_USES
)
3939 reg_use_table
[reg_use_count
].reg_rtx
= x
;
3943 /* Recursively scan the operands of this expression. */
3945 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3949 /* If we are about to do the last recursive call
3950 needed at this level, change it into iteration.
3951 This function is called enough to be worth it. */
3958 find_used_regs (&XEXP (x
, i
), data
);
3960 else if (fmt
[i
] == 'E')
3961 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3962 find_used_regs (&XVECEXP (x
, i
, j
), data
);
3966 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
3967 Returns non-zero is successful. */
3970 try_replace_reg (from
, to
, insn
)
3973 rtx note
= find_reg_equal_equiv_note (insn
);
3976 rtx set
= single_set (insn
);
3978 if (reg_mentioned_p (from
, PATTERN (insn
)))
3980 success
= validate_replace_src (from
, to
, insn
);
3983 if (!success
&& set
&& reg_mentioned_p (from
, SET_SRC (set
)))
3985 /* If above failed and this is a single set, try to simplify the source of
3986 the set given our substitution. We could perhaps try this for multiple
3987 SETs, but it probably won't buy us anything. */
3988 src
= simplify_replace_rtx (SET_SRC (set
), from
, to
);
3990 if (!rtx_equal_p (src
, SET_SRC (set
))
3991 && validate_change (insn
, &SET_SRC (set
), src
, 0))
3994 /* If we've failed to do replacement, have a single SET, and don't already
3995 have a note, add a REG_EQUAL note to not lose information. */
3996 if (!success
&& note
== 0 && set
!= 0)
3997 note
= set_unique_reg_note (insn
, REG_EQUAL
, copy_rtx (src
));
4000 /* If there is already a NOTE, update the expression in it with our
4003 XEXP (note
, 0) = simplify_replace_rtx (XEXP (note
, 0), from
, to
);
4005 /* REG_EQUAL may get simplified into register.
4006 We don't allow that. Remove that note. This code ought
4007 not to hapen, because previous code ought to syntetize
4008 reg-reg move, but be on the safe side. */
4009 if (note
&& REG_P (XEXP (note
, 0)))
4010 remove_note (insn
, note
);
4015 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
4016 NULL no such set is found. */
4018 static struct expr
*
4019 find_avail_set (regno
, insn
)
4023 /* SET1 contains the last set found that can be returned to the caller for
4024 use in a substitution. */
4025 struct expr
*set1
= 0;
4027 /* Loops are not possible here. To get a loop we would need two sets
4028 available at the start of the block containing INSN. ie we would
4029 need two sets like this available at the start of the block:
4031 (set (reg X) (reg Y))
4032 (set (reg Y) (reg X))
4034 This can not happen since the set of (reg Y) would have killed the
4035 set of (reg X) making it unavailable at the start of this block. */
4039 struct expr
*set
= lookup_set (regno
, NULL_RTX
);
4041 /* Find a set that is available at the start of the block
4042 which contains INSN. */
4045 if (TEST_BIT (cprop_avin
[BLOCK_NUM (insn
)], set
->bitmap_index
))
4047 set
= next_set (regno
, set
);
4050 /* If no available set was found we've reached the end of the
4051 (possibly empty) copy chain. */
4055 if (GET_CODE (set
->expr
) != SET
)
4058 src
= SET_SRC (set
->expr
);
4060 /* We know the set is available.
4061 Now check that SRC is ANTLOC (i.e. none of the source operands
4062 have changed since the start of the block).
4064 If the source operand changed, we may still use it for the next
4065 iteration of this loop, but we may not use it for substitutions. */
4067 if (CONSTANT_P (src
) || oprs_not_set_p (src
, insn
))
4070 /* If the source of the set is anything except a register, then
4071 we have reached the end of the copy chain. */
4072 if (GET_CODE (src
) != REG
)
4075 /* Follow the copy chain, ie start another iteration of the loop
4076 and see if we have an available copy into SRC. */
4077 regno
= REGNO (src
);
4080 /* SET1 holds the last set that was available and anticipatable at
4085 /* Subroutine of cprop_insn that tries to propagate constants into
4086 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
4087 it is the instruction that immediately preceeds JUMP, and must be a
4088 single SET of a register. FROM is what we will try to replace,
4089 SRC is the constant we will try to substitute for it. Returns nonzero
4090 if a change was made. */
4093 cprop_jump (bb
, setcc
, jump
, from
, src
)
4101 rtx set
= pc_set (jump
);
4103 /* First substitute in the INSN condition as the SET_SRC of the JUMP,
4104 then substitute that given values in this expanded JUMP. */
4107 rtx setcc_set
= single_set (setcc
);
4108 new_set
= simplify_replace_rtx (SET_SRC (set
),
4109 SET_DEST (setcc_set
),
4110 SET_SRC (setcc_set
));
4115 new = simplify_replace_rtx (new_set
, from
, src
);
4117 /* If no simplification can be made, then try the next
4119 if (rtx_equal_p (new, new_set
))
4122 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
4127 if (! validate_change (jump
, &SET_SRC (set
), new, 0))
4130 /* If this has turned into an unconditional jump,
4131 then put a barrier after it so that the unreachable
4132 code will be deleted. */
4133 if (GET_CODE (SET_SRC (set
)) == LABEL_REF
)
4134 emit_barrier_after (jump
);
4138 /* Delete the cc0 setter. */
4139 if (setcc
!= NULL
&& CC0_P (SET_DEST (single_set (setcc
))))
4140 delete_insn (setcc
);
4143 run_jump_opt_after_gcse
= 1;
4146 if (gcse_file
!= NULL
)
4149 "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
4150 REGNO (from
), INSN_UID (jump
));
4151 print_rtl (gcse_file
, src
);
4152 fprintf (gcse_file
, "\n");
4154 purge_dead_edges (bb
);
4160 constprop_register (insn
, from
, to
, alter_jumps
)
4168 /* Check for reg or cc0 setting instructions followed by
4169 conditional branch instructions first. */
4171 && (sset
= single_set (insn
)) != NULL
4172 && any_condjump_p (NEXT_INSN (insn
)) && onlyjump_p (NEXT_INSN (insn
)))
4174 rtx dest
= SET_DEST (sset
);
4175 if ((REG_P (dest
) || CC0_P (dest
))
4176 && cprop_jump (BLOCK_FOR_INSN (insn
), insn
, NEXT_INSN (insn
), from
, to
))
4180 /* Handle normal insns next. */
4181 if (GET_CODE (insn
) == INSN
4182 && try_replace_reg (from
, to
, insn
))
4185 /* Try to propagate a CONST_INT into a conditional jump.
4186 We're pretty specific about what we will handle in this
4187 code, we can extend this as necessary over time.
4189 Right now the insn in question must look like
4190 (set (pc) (if_then_else ...)) */
4191 else if (alter_jumps
&& any_condjump_p (insn
) && onlyjump_p (insn
))
4192 return cprop_jump (BLOCK_FOR_INSN (insn
), NULL
, insn
, from
, to
);
4196 /* Perform constant and copy propagation on INSN.
4197 The result is non-zero if a change was made. */
4200 cprop_insn (insn
, alter_jumps
)
4204 struct reg_use
*reg_used
;
4212 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4214 note
= find_reg_equal_equiv_note (insn
);
4216 /* We may win even when propagating constants into notes. */
4218 find_used_regs (&XEXP (note
, 0), NULL
);
4220 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
4221 reg_used
++, reg_use_count
--)
4223 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
4227 /* Ignore registers created by GCSE.
4228 We do this because ... */
4229 if (regno
>= max_gcse_regno
)
4232 /* If the register has already been set in this block, there's
4233 nothing we can do. */
4234 if (! oprs_not_set_p (reg_used
->reg_rtx
, insn
))
4237 /* Find an assignment that sets reg_used and is available
4238 at the start of the block. */
4239 set
= find_avail_set (regno
, insn
);
4244 /* ??? We might be able to handle PARALLELs. Later. */
4245 if (GET_CODE (pat
) != SET
)
4248 src
= SET_SRC (pat
);
4250 /* Constant propagation. */
4251 if (CONSTANT_P (src
))
4253 if (constprop_register (insn
, reg_used
->reg_rtx
, src
, alter_jumps
))
4257 if (gcse_file
!= NULL
)
4259 fprintf (gcse_file
, "GLOBAL CONST-PROP: Replacing reg %d in ", regno
);
4260 fprintf (gcse_file
, "insn %d with constant ", INSN_UID (insn
));
4261 print_rtl (gcse_file
, src
);
4262 fprintf (gcse_file
, "\n");
4266 else if (GET_CODE (src
) == REG
4267 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
4268 && REGNO (src
) != regno
)
4270 if (try_replace_reg (reg_used
->reg_rtx
, src
, insn
))
4274 if (gcse_file
!= NULL
)
4276 fprintf (gcse_file
, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
4277 regno
, INSN_UID (insn
));
4278 fprintf (gcse_file
, " with reg %d\n", REGNO (src
));
4281 /* The original insn setting reg_used may or may not now be
4282 deletable. We leave the deletion to flow. */
4283 /* FIXME: If it turns out that the insn isn't deletable,
4284 then we may have unnecessarily extended register lifetimes
4285 and made things worse. */
4294 do_local_cprop (x
, insn
, alter_jumps
)
4299 rtx newreg
= NULL
, newcnst
= NULL
;
4301 /* Rule out USE instructions and ASM statements as we don't want to change the hard
4302 registers mentioned. */
4303 if (GET_CODE (x
) == REG
4304 && (REGNO (x
) >= FIRST_PSEUDO_REGISTER
4305 || (GET_CODE (PATTERN (insn
)) != USE
&& asm_noperands (PATTERN (insn
)) < 0)))
4307 cselib_val
*val
= cselib_lookup (x
, GET_MODE (x
), 0);
4308 struct elt_loc_list
*l
;
4312 for (l
= val
->locs
; l
; l
= l
->next
)
4314 rtx this_rtx
= l
->loc
;
4317 if (CONSTANT_P (this_rtx
))
4319 if (REG_P (this_rtx
) && REGNO (this_rtx
) >= FIRST_PSEUDO_REGISTER
4320 /* Don't copy propagate if it has attached REG_EQUIV note.
4321 At this point this only function parameters should have
4322 REG_EQUIV notes and if the argument slot is used somewhere
4323 explicitly, it means address of parameter has been taken,
4324 so we should not extend the lifetime of the pseudo. */
4325 && (!(note
= find_reg_note (l
->setting_insn
, REG_EQUIV
, NULL_RTX
))
4326 || GET_CODE (XEXP (note
, 0)) != MEM
))
4329 if (newcnst
&& constprop_register (insn
, x
, newcnst
, alter_jumps
))
4331 if (gcse_file
!= NULL
)
4333 fprintf (gcse_file
, "LOCAL CONST-PROP: Replacing reg %d in ",
4335 fprintf (gcse_file
, "insn %d with constant ",
4337 print_rtl (gcse_file
, newcnst
);
4338 fprintf (gcse_file
, "\n");
4343 else if (newreg
&& newreg
!= x
&& try_replace_reg (x
, newreg
, insn
))
4345 if (gcse_file
!= NULL
)
4348 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
4349 REGNO (x
), INSN_UID (insn
));
4350 fprintf (gcse_file
, " with reg %d\n", REGNO (newreg
));
4360 local_cprop_pass (alter_jumps
)
4364 struct reg_use
*reg_used
;
4367 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4371 rtx note
= find_reg_equal_equiv_note (insn
);
4376 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4378 find_used_regs (&XEXP (note
, 0), NULL
);
4380 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
4381 reg_used
++, reg_use_count
--)
4382 if (do_local_cprop (reg_used
->reg_rtx
, insn
, alter_jumps
))
4385 while (reg_use_count
);
4387 cselib_process_insn (insn
);
4392 /* Forward propagate copies. This includes copies and constants. Return
4393 non-zero if a change was made. */
4403 /* Note we start at block 1. */
4404 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
4406 if (gcse_file
!= NULL
)
4407 fprintf (gcse_file
, "\n");
4412 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
4414 /* Reset tables used to keep track of what's still valid [since the
4415 start of the block]. */
4416 reset_opr_set_tables ();
4418 for (insn
= bb
->head
;
4419 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
4420 insn
= NEXT_INSN (insn
))
4423 changed
|= cprop_insn (insn
, alter_jumps
);
4425 /* Keep track of everything modified by this insn. */
4426 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
4427 call mark_oprs_set if we turned the insn into a NOTE. */
4428 if (GET_CODE (insn
) != NOTE
)
4429 mark_oprs_set (insn
);
4433 if (gcse_file
!= NULL
)
4434 fprintf (gcse_file
, "\n");
4439 /* Perform one copy/constant propagation pass.
4440 F is the first insn in the function.
4441 PASS is the pass count. */
4444 one_cprop_pass (pass
, alter_jumps
)
4450 const_prop_count
= 0;
4451 copy_prop_count
= 0;
4453 local_cprop_pass (alter_jumps
);
4455 alloc_set_hash_table (max_cuid
);
4456 compute_set_hash_table ();
4458 dump_hash_table (gcse_file
, "SET", set_hash_table
, set_hash_table_size
,
4462 alloc_cprop_mem (last_basic_block
, n_sets
);
4463 compute_cprop_data ();
4464 changed
= cprop (alter_jumps
);
4466 changed
|= bypass_conditional_jumps ();
4470 free_set_hash_table ();
4474 fprintf (gcse_file
, "CPROP of %s, pass %d: %d bytes needed, ",
4475 current_function_name
, pass
, bytes_used
);
4476 fprintf (gcse_file
, "%d const props, %d copy props\n\n",
4477 const_prop_count
, copy_prop_count
);
4483 /* Bypass conditional jumps. */
4485 /* Find a set of REGNO to a constant that is available at the end of basic
4486 block BB. Returns NULL if no such set is found. Based heavily upon
4489 static struct expr
*
4490 find_bypass_set (regno
, bb
)
4494 struct expr
*result
= 0;
4499 struct expr
*set
= lookup_set (regno
, NULL_RTX
);
4503 if (TEST_BIT (cprop_avout
[bb
], set
->bitmap_index
))
4505 set
= next_set (regno
, set
);
4511 if (GET_CODE (set
->expr
) != SET
)
4514 src
= SET_SRC (set
->expr
);
4515 if (CONSTANT_P (src
))
4518 if (GET_CODE (src
) != REG
)
4521 regno
= REGNO (src
);
4527 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
4528 basic block BB which has more than one predecessor. If not NULL, SETCC
4529 is the first instruction of BB, which is immediately followed by JUMP_INSN
4530 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
4531 Returns nonzero if a change was made. */
4534 bypass_block (bb
, setcc
, jump
)
4542 insn
= (setcc
!= NULL
) ? setcc
: jump
;
4544 /* Determine set of register uses in INSN. */
4546 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4547 note
= find_reg_equal_equiv_note (insn
);
4549 find_used_regs (&XEXP (note
, 0), NULL
);
4552 for (e
= bb
->pred
; e
; e
= enext
)
4554 enext
= e
->pred_next
;
4555 for (i
= 0; i
< reg_use_count
; i
++)
4557 struct reg_use
*reg_used
= ®_use_table
[i
];
4558 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
4559 basic_block dest
, old_dest
;
4563 if (regno
>= max_gcse_regno
)
4566 set
= find_bypass_set (regno
, e
->src
->index
);
4571 src
= SET_SRC (pc_set (jump
));
4574 src
= simplify_replace_rtx (src
,
4575 SET_DEST (PATTERN (setcc
)),
4576 SET_SRC (PATTERN (setcc
)));
4578 new = simplify_replace_rtx (src
, reg_used
->reg_rtx
,
4579 SET_SRC (set
->expr
));
4582 dest
= FALLTHRU_EDGE (bb
)->dest
;
4583 else if (GET_CODE (new) == LABEL_REF
)
4584 dest
= BRANCH_EDGE (bb
)->dest
;
4588 /* Once basic block indices are stable, we should be able
4589 to use redirect_edge_and_branch_force instead. */
4591 if (dest
!= NULL
&& dest
!= old_dest
4592 && redirect_edge_and_branch (e
, dest
))
4594 /* Copy the register setter to the redirected edge.
4595 Don't copy CC0 setters, as CC0 is dead after jump. */
4598 rtx pat
= PATTERN (setcc
);
4599 if (!CC0_P (SET_DEST (pat
)))
4600 insert_insn_on_edge (copy_insn (pat
), e
);
4603 if (gcse_file
!= NULL
)
4605 fprintf (gcse_file
, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
4606 regno
, INSN_UID (jump
));
4607 print_rtl (gcse_file
, SET_SRC (set
->expr
));
4608 fprintf (gcse_file
, "\nBypass edge from %d->%d to %d\n",
4609 e
->src
->index
, old_dest
->index
, dest
->index
);
4619 /* Find basic blocks with more than one predecessor that only contain a
4620 single conditional jump. If the result of the comparison is known at
4621 compile-time from any incoming edge, redirect that edge to the
4622 appropriate target. Returns nonzero if a change was made. */
4625 bypass_conditional_jumps ()
4633 /* Note we start at block 1. */
4634 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
4638 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
,
4639 EXIT_BLOCK_PTR
, next_bb
)
4641 /* Check for more than one predecessor. */
4642 if (bb
->pred
&& bb
->pred
->pred_next
)
4645 for (insn
= bb
->head
;
4646 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
4647 insn
= NEXT_INSN (insn
))
4648 if (GET_CODE (insn
) == INSN
)
4652 if (GET_CODE (PATTERN (insn
)) != SET
)
4655 dest
= SET_DEST (PATTERN (insn
));
4656 if (REG_P (dest
) || CC0_P (dest
))
4661 else if (GET_CODE (insn
) == JUMP_INSN
)
4663 if (any_condjump_p (insn
) && onlyjump_p (insn
))
4664 changed
|= bypass_block (bb
, setcc
, insn
);
4667 else if (INSN_P (insn
))
4672 /* If we bypassed any register setting insns, we inserted a
4673 copy on the redirected edge. These need to be commited. */
4675 commit_edge_insertions();
4680 /* Compute PRE+LCM working variables. */
4682 /* Local properties of expressions. */
4683 /* Nonzero for expressions that are transparent in the block. */
4684 static sbitmap
*transp
;
4686 /* Nonzero for expressions that are transparent at the end of the block.
4687 This is only zero for expressions killed by abnormal critical edge
4688 created by a calls. */
4689 static sbitmap
*transpout
;
4691 /* Nonzero for expressions that are computed (available) in the block. */
4692 static sbitmap
*comp
;
4694 /* Nonzero for expressions that are locally anticipatable in the block. */
4695 static sbitmap
*antloc
;
4697 /* Nonzero for expressions where this block is an optimal computation
4699 static sbitmap
*pre_optimal
;
4701 /* Nonzero for expressions which are redundant in a particular block. */
4702 static sbitmap
*pre_redundant
;
4704 /* Nonzero for expressions which should be inserted on a specific edge. */
4705 static sbitmap
*pre_insert_map
;
4707 /* Nonzero for expressions which should be deleted in a specific block. */
4708 static sbitmap
*pre_delete_map
;
4710 /* Contains the edge_list returned by pre_edge_lcm. */
4711 static struct edge_list
*edge_list
;
4713 /* Redundant insns. */
4714 static sbitmap pre_redundant_insns
;
4716 /* Allocate vars used for PRE analysis. */
4719 alloc_pre_mem (n_blocks
, n_exprs
)
4720 int n_blocks
, n_exprs
;
4722 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4723 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4724 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4727 pre_redundant
= NULL
;
4728 pre_insert_map
= NULL
;
4729 pre_delete_map
= NULL
;
4732 ae_kill
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4734 /* pre_insert and pre_delete are allocated later. */
4737 /* Free vars used for PRE analysis. */
4742 sbitmap_vector_free (transp
);
4743 sbitmap_vector_free (comp
);
4745 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
4748 sbitmap_vector_free (pre_optimal
);
4750 sbitmap_vector_free (pre_redundant
);
4752 sbitmap_vector_free (pre_insert_map
);
4754 sbitmap_vector_free (pre_delete_map
);
4756 sbitmap_vector_free (ae_in
);
4758 sbitmap_vector_free (ae_out
);
4760 transp
= comp
= NULL
;
4761 pre_optimal
= pre_redundant
= pre_insert_map
= pre_delete_map
= NULL
;
4762 ae_in
= ae_out
= NULL
;
4765 /* Top level routine to do the dataflow analysis needed by PRE. */
4770 sbitmap trapping_expr
;
4774 compute_local_properties (transp
, comp
, antloc
, 0);
4775 sbitmap_vector_zero (ae_kill
, last_basic_block
);
4777 /* Collect expressions which might trap. */
4778 trapping_expr
= sbitmap_alloc (n_exprs
);
4779 sbitmap_zero (trapping_expr
);
4780 for (ui
= 0; ui
< expr_hash_table_size
; ui
++)
4783 for (e
= expr_hash_table
[ui
]; e
!= NULL
; e
= e
->next_same_hash
)
4784 if (may_trap_p (e
->expr
))
4785 SET_BIT (trapping_expr
, e
->bitmap_index
);
4788 /* Compute ae_kill for each basic block using:
4792 This is significantly faster than compute_ae_kill. */
4798 /* If the current block is the destination of an abnormal edge, we
4799 kill all trapping expressions because we won't be able to properly
4800 place the instruction on the edge. So make them neither
4801 anticipatable nor transparent. This is fairly conservative. */
4802 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
4803 if (e
->flags
& EDGE_ABNORMAL
)
4805 sbitmap_difference (antloc
[bb
->index
], antloc
[bb
->index
], trapping_expr
);
4806 sbitmap_difference (transp
[bb
->index
], transp
[bb
->index
], trapping_expr
);
4810 sbitmap_a_or_b (ae_kill
[bb
->index
], transp
[bb
->index
], comp
[bb
->index
]);
4811 sbitmap_not (ae_kill
[bb
->index
], ae_kill
[bb
->index
]);
4814 edge_list
= pre_edge_lcm (gcse_file
, n_exprs
, transp
, comp
, antloc
,
4815 ae_kill
, &pre_insert_map
, &pre_delete_map
);
4816 sbitmap_vector_free (antloc
);
4818 sbitmap_vector_free (ae_kill
);
4820 sbitmap_free (trapping_expr
);
4825 /* Return non-zero if an occurrence of expression EXPR in OCCR_BB would reach
4828 VISITED is a pointer to a working buffer for tracking which BB's have
4829 been visited. It is NULL for the top-level call.
4831 We treat reaching expressions that go through blocks containing the same
4832 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
4833 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
4834 2 as not reaching. The intent is to improve the probability of finding
4835 only one reaching expression and to reduce register lifetimes by picking
4836 the closest such expression. */
4839 pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
)
4840 basic_block occr_bb
;
4847 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
4849 basic_block pred_bb
= pred
->src
;
4851 if (pred
->src
== ENTRY_BLOCK_PTR
4852 /* Has predecessor has already been visited? */
4853 || visited
[pred_bb
->index
])
4854 ;/* Nothing to do. */
4856 /* Does this predecessor generate this expression? */
4857 else if (TEST_BIT (comp
[pred_bb
->index
], expr
->bitmap_index
))
4859 /* Is this the occurrence we're looking for?
4860 Note that there's only one generating occurrence per block
4861 so we just need to check the block number. */
4862 if (occr_bb
== pred_bb
)
4865 visited
[pred_bb
->index
] = 1;
4867 /* Ignore this predecessor if it kills the expression. */
4868 else if (! TEST_BIT (transp
[pred_bb
->index
], expr
->bitmap_index
))
4869 visited
[pred_bb
->index
] = 1;
4871 /* Neither gen nor kill. */
4874 visited
[pred_bb
->index
] = 1;
4875 if (pre_expr_reaches_here_p_work (occr_bb
, expr
, pred_bb
, visited
))
4880 /* All paths have been checked. */
4884 /* The wrapper for pre_expr_reaches_here_work that ensures that any
4885 memory allocated for that function is returned. */
4888 pre_expr_reaches_here_p (occr_bb
, expr
, bb
)
4889 basic_block occr_bb
;
4894 char *visited
= (char *) xcalloc (last_basic_block
, 1);
4896 rval
= pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
);
4903 /* Given an expr, generate RTL which we can insert at the end of a BB,
4904 or on an edge. Set the block number of any insns generated to
4908 process_insert_insn (expr
)
4911 rtx reg
= expr
->reaching_reg
;
4912 rtx exp
= copy_rtx (expr
->expr
);
4917 /* If the expression is something that's an operand, like a constant,
4918 just copy it to a register. */
4919 if (general_operand (exp
, GET_MODE (reg
)))
4920 emit_move_insn (reg
, exp
);
4922 /* Otherwise, make a new insn to compute this expression and make sure the
4923 insn will be recognized (this also adds any needed CLOBBERs). Copy the
4924 expression to make sure we don't have any sharing issues. */
4925 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode
, reg
, exp
))))
4934 /* Add EXPR to the end of basic block BB.
4936 This is used by both the PRE and code hoisting.
4938 For PRE, we want to verify that the expr is either transparent
4939 or locally anticipatable in the target block. This check makes
4940 no sense for code hoisting. */
4943 insert_insn_end_bb (expr
, bb
, pre
)
4950 rtx reg
= expr
->reaching_reg
;
4951 int regno
= REGNO (reg
);
4954 pat
= process_insert_insn (expr
);
4955 if (pat
== NULL_RTX
|| ! INSN_P (pat
))
4959 while (NEXT_INSN (pat_end
) != NULL_RTX
)
4960 pat_end
= NEXT_INSN (pat_end
);
4962 /* If the last insn is a jump, insert EXPR in front [taking care to
4963 handle cc0, etc. properly]. Similary we need to care trapping
4964 instructions in presence of non-call exceptions. */
4966 if (GET_CODE (insn
) == JUMP_INSN
4967 || (GET_CODE (insn
) == INSN
4968 && (bb
->succ
->succ_next
|| (bb
->succ
->flags
& EDGE_ABNORMAL
))))
4973 /* It should always be the case that we can put these instructions
4974 anywhere in the basic block with performing PRE optimizations.
4976 if (GET_CODE (insn
) == INSN
&& pre
4977 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
4978 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
4981 /* If this is a jump table, then we can't insert stuff here. Since
4982 we know the previous real insn must be the tablejump, we insert
4983 the new instruction just before the tablejump. */
4984 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
4985 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
4986 insn
= prev_real_insn (insn
);
4989 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4990 if cc0 isn't set. */
4991 note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
4993 insn
= XEXP (note
, 0);
4996 rtx maybe_cc0_setter
= prev_nonnote_insn (insn
);
4997 if (maybe_cc0_setter
4998 && INSN_P (maybe_cc0_setter
)
4999 && sets_cc0_p (PATTERN (maybe_cc0_setter
)))
5000 insn
= maybe_cc0_setter
;
5003 /* FIXME: What if something in cc0/jump uses value set in new insn? */
5004 new_insn
= emit_insn_before (pat
, insn
);
5007 /* Likewise if the last insn is a call, as will happen in the presence
5008 of exception handling. */
5009 else if (GET_CODE (insn
) == CALL_INSN
5010 && (bb
->succ
->succ_next
|| (bb
->succ
->flags
& EDGE_ABNORMAL
)))
5012 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
5013 we search backward and place the instructions before the first
5014 parameter is loaded. Do this for everyone for consistency and a
5015 presumtion that we'll get better code elsewhere as well.
5017 It should always be the case that we can put these instructions
5018 anywhere in the basic block with performing PRE optimizations.
5022 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
5023 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
5026 /* Since different machines initialize their parameter registers
5027 in different orders, assume nothing. Collect the set of all
5028 parameter registers. */
5029 insn
= find_first_parameter_load (insn
, bb
->head
);
5031 /* If we found all the parameter loads, then we want to insert
5032 before the first parameter load.
5034 If we did not find all the parameter loads, then we might have
5035 stopped on the head of the block, which could be a CODE_LABEL.
5036 If we inserted before the CODE_LABEL, then we would be putting
5037 the insn in the wrong basic block. In that case, put the insn
5038 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
5039 while (GET_CODE (insn
) == CODE_LABEL
5040 || NOTE_INSN_BASIC_BLOCK_P (insn
))
5041 insn
= NEXT_INSN (insn
);
5043 new_insn
= emit_insn_before (pat
, insn
);
5046 new_insn
= emit_insn_after (pat
, insn
);
5052 add_label_notes (PATTERN (pat
), new_insn
);
5053 note_stores (PATTERN (pat
), record_set_info
, pat
);
5057 pat
= NEXT_INSN (pat
);
5060 gcse_create_count
++;
5064 fprintf (gcse_file
, "PRE/HOIST: end of bb %d, insn %d, ",
5065 bb
->index
, INSN_UID (new_insn
));
5066 fprintf (gcse_file
, "copying expression %d to reg %d\n",
5067 expr
->bitmap_index
, regno
);
5071 /* Insert partially redundant expressions on edges in the CFG to make
5072 the expressions fully redundant. */
5075 pre_edge_insert (edge_list
, index_map
)
5076 struct edge_list
*edge_list
;
5077 struct expr
**index_map
;
5079 int e
, i
, j
, num_edges
, set_size
, did_insert
= 0;
5082 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
5083 if it reaches any of the deleted expressions. */
5085 set_size
= pre_insert_map
[0]->size
;
5086 num_edges
= NUM_EDGES (edge_list
);
5087 inserted
= sbitmap_vector_alloc (num_edges
, n_exprs
);
5088 sbitmap_vector_zero (inserted
, num_edges
);
5090 for (e
= 0; e
< num_edges
; e
++)
5093 basic_block bb
= INDEX_EDGE_PRED_BB (edge_list
, e
);
5095 for (i
= indx
= 0; i
< set_size
; i
++, indx
+= SBITMAP_ELT_BITS
)
5097 SBITMAP_ELT_TYPE insert
= pre_insert_map
[e
]->elms
[i
];
5099 for (j
= indx
; insert
&& j
< n_exprs
; j
++, insert
>>= 1)
5100 if ((insert
& 1) != 0 && index_map
[j
]->reaching_reg
!= NULL_RTX
)
5102 struct expr
*expr
= index_map
[j
];
5105 /* Now look at each deleted occurrence of this expression. */
5106 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5108 if (! occr
->deleted_p
)
5111 /* Insert this expression on this edge if if it would
5112 reach the deleted occurrence in BB. */
5113 if (!TEST_BIT (inserted
[e
], j
))
5116 edge eg
= INDEX_EDGE (edge_list
, e
);
5118 /* We can't insert anything on an abnormal and
5119 critical edge, so we insert the insn at the end of
5120 the previous block. There are several alternatives
5121 detailed in Morgans book P277 (sec 10.5) for
5122 handling this situation. This one is easiest for
5125 if ((eg
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
5126 insert_insn_end_bb (index_map
[j
], bb
, 0);
5129 insn
= process_insert_insn (index_map
[j
]);
5130 insert_insn_on_edge (insn
, eg
);
5135 fprintf (gcse_file
, "PRE/HOIST: edge (%d,%d), ",
5137 INDEX_EDGE_SUCC_BB (edge_list
, e
)->index
);
5138 fprintf (gcse_file
, "copy expression %d\n",
5139 expr
->bitmap_index
);
5142 update_ld_motion_stores (expr
);
5143 SET_BIT (inserted
[e
], j
);
5145 gcse_create_count
++;
5152 sbitmap_vector_free (inserted
);
5156 /* Copy the result of INSN to REG. INDX is the expression number. */
5159 pre_insert_copy_insn (expr
, insn
)
5163 rtx reg
= expr
->reaching_reg
;
5164 int regno
= REGNO (reg
);
5165 int indx
= expr
->bitmap_index
;
5166 rtx set
= single_set (insn
);
5172 new_insn
= emit_insn_after (gen_move_insn (reg
, SET_DEST (set
)), insn
);
5174 /* Keep register set table up to date. */
5175 record_one_set (regno
, new_insn
);
5177 gcse_create_count
++;
5181 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
5182 BLOCK_NUM (insn
), INSN_UID (new_insn
), indx
,
5183 INSN_UID (insn
), regno
);
5184 update_ld_motion_stores (expr
);
5187 /* Copy available expressions that reach the redundant expression
5188 to `reaching_reg'. */
5191 pre_insert_copies ()
5198 /* For each available expression in the table, copy the result to
5199 `reaching_reg' if the expression reaches a deleted one.
5201 ??? The current algorithm is rather brute force.
5202 Need to do some profiling. */
5204 for (i
= 0; i
< expr_hash_table_size
; i
++)
5205 for (expr
= expr_hash_table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5207 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
5208 we don't want to insert a copy here because the expression may not
5209 really be redundant. So only insert an insn if the expression was
5210 deleted. This test also avoids further processing if the
5211 expression wasn't deleted anywhere. */
5212 if (expr
->reaching_reg
== NULL
)
5215 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5217 if (! occr
->deleted_p
)
5220 for (avail
= expr
->avail_occr
; avail
!= NULL
; avail
= avail
->next
)
5222 rtx insn
= avail
->insn
;
5224 /* No need to handle this one if handled already. */
5225 if (avail
->copied_p
)
5228 /* Don't handle this one if it's a redundant one. */
5229 if (TEST_BIT (pre_redundant_insns
, INSN_CUID (insn
)))
5232 /* Or if the expression doesn't reach the deleted one. */
5233 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail
->insn
),
5235 BLOCK_FOR_INSN (occr
->insn
)))
5238 /* Copy the result of avail to reaching_reg. */
5239 pre_insert_copy_insn (expr
, insn
);
5240 avail
->copied_p
= 1;
5246 /* Emit move from SRC to DEST noting the equivalence with expression computed
5249 gcse_emit_move_after (src
, dest
, insn
)
5250 rtx src
, dest
, insn
;
5253 rtx set
= single_set (insn
), set2
;
5257 /* This should never fail since we're creating a reg->reg copy
5258 we've verified to be valid. */
5260 new = emit_insn_after (gen_move_insn (dest
, src
), insn
);
5262 /* Note the equivalence for local CSE pass. */
5263 set2
= single_set (new);
5264 if (!set2
|| !rtx_equal_p (SET_DEST (set2
), dest
))
5266 if ((note
= find_reg_equal_equiv_note (insn
)))
5267 eqv
= XEXP (note
, 0);
5269 eqv
= SET_SRC (set
);
5271 set_unique_reg_note (new, REG_EQUAL
, copy_insn_1 (src
));
5276 /* Delete redundant computations.
5277 Deletion is done by changing the insn to copy the `reaching_reg' of
5278 the expression into the result of the SET. It is left to later passes
5279 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
5281 Returns non-zero if a change is made. */
5292 for (i
= 0; i
< expr_hash_table_size
; i
++)
5293 for (expr
= expr_hash_table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5295 int indx
= expr
->bitmap_index
;
5297 /* We only need to search antic_occr since we require
5300 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5302 rtx insn
= occr
->insn
;
5304 basic_block bb
= BLOCK_FOR_INSN (insn
);
5306 if (TEST_BIT (pre_delete_map
[bb
->index
], indx
))
5308 set
= single_set (insn
);
5312 /* Create a pseudo-reg to store the result of reaching
5313 expressions into. Get the mode for the new pseudo from
5314 the mode of the original destination pseudo. */
5315 if (expr
->reaching_reg
== NULL
)
5317 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
5319 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
5321 occr
->deleted_p
= 1;
5322 SET_BIT (pre_redundant_insns
, INSN_CUID (insn
));
5329 "PRE: redundant insn %d (expression %d) in ",
5330 INSN_UID (insn
), indx
);
5331 fprintf (gcse_file
, "bb %d, reaching reg is %d\n",
5332 bb
->index
, REGNO (expr
->reaching_reg
));
5341 /* Perform GCSE optimizations using PRE.
5342 This is called by one_pre_gcse_pass after all the dataflow analysis
5345 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
5346 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
5347 Compiler Design and Implementation.
5349 ??? A new pseudo reg is created to hold the reaching expression. The nice
5350 thing about the classical approach is that it would try to use an existing
5351 reg. If the register can't be adequately optimized [i.e. we introduce
5352 reload problems], one could add a pass here to propagate the new register
5355 ??? We don't handle single sets in PARALLELs because we're [currently] not
5356 able to copy the rest of the parallel when we insert copies to create full
5357 redundancies from partial redundancies. However, there's no reason why we
5358 can't handle PARALLELs in the cases where there are no partial
5365 int did_insert
, changed
;
5366 struct expr
**index_map
;
5369 /* Compute a mapping from expression number (`bitmap_index') to
5370 hash table entry. */
5372 index_map
= (struct expr
**) xcalloc (n_exprs
, sizeof (struct expr
*));
5373 for (i
= 0; i
< expr_hash_table_size
; i
++)
5374 for (expr
= expr_hash_table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5375 index_map
[expr
->bitmap_index
] = expr
;
5377 /* Reset bitmap used to track which insns are redundant. */
5378 pre_redundant_insns
= sbitmap_alloc (max_cuid
);
5379 sbitmap_zero (pre_redundant_insns
);
5381 /* Delete the redundant insns first so that
5382 - we know what register to use for the new insns and for the other
5383 ones with reaching expressions
5384 - we know which insns are redundant when we go to create copies */
5386 changed
= pre_delete ();
5388 did_insert
= pre_edge_insert (edge_list
, index_map
);
5390 /* In other places with reaching expressions, copy the expression to the
5391 specially allocated pseudo-reg that reaches the redundant expr. */
5392 pre_insert_copies ();
5395 commit_edge_insertions ();
5400 sbitmap_free (pre_redundant_insns
);
5404 /* Top level routine to perform one PRE GCSE pass.
5406 Return non-zero if a change was made. */
5409 one_pre_gcse_pass (pass
)
5414 gcse_subst_count
= 0;
5415 gcse_create_count
= 0;
5417 alloc_expr_hash_table (max_cuid
);
5418 add_noreturn_fake_exit_edges ();
5420 compute_ld_motion_mems ();
5422 compute_expr_hash_table ();
5423 trim_ld_motion_mems ();
5425 dump_hash_table (gcse_file
, "Expression", expr_hash_table
,
5426 expr_hash_table_size
, n_exprs
);
5430 alloc_pre_mem (last_basic_block
, n_exprs
);
5431 compute_pre_data ();
5432 changed
|= pre_gcse ();
5433 free_edge_list (edge_list
);
5438 remove_fake_edges ();
5439 free_expr_hash_table ();
5443 fprintf (gcse_file
, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
5444 current_function_name
, pass
, bytes_used
);
5445 fprintf (gcse_file
, "%d substs, %d insns created\n",
5446 gcse_subst_count
, gcse_create_count
);
5452 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
5453 If notes are added to an insn which references a CODE_LABEL, the
5454 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
5455 because the following loop optimization pass requires them. */
5457 /* ??? This is very similar to the loop.c add_label_notes function. We
5458 could probably share code here. */
5460 /* ??? If there was a jump optimization pass after gcse and before loop,
5461 then we would not need to do this here, because jump would add the
5462 necessary REG_LABEL notes. */
5465 add_label_notes (x
, insn
)
5469 enum rtx_code code
= GET_CODE (x
);
5473 if (code
== LABEL_REF
&& !LABEL_REF_NONLOCAL_P (x
))
5475 /* This code used to ignore labels that referred to dispatch tables to
5476 avoid flow generating (slighly) worse code.
5478 We no longer ignore such label references (see LABEL_REF handling in
5479 mark_jump_label for additional information). */
5481 REG_NOTES (insn
) = gen_rtx_INSN_LIST (REG_LABEL
, XEXP (x
, 0),
5483 if (LABEL_P (XEXP (x
, 0)))
5484 LABEL_NUSES (XEXP (x
, 0))++;
5488 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
5491 add_label_notes (XEXP (x
, i
), insn
);
5492 else if (fmt
[i
] == 'E')
5493 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5494 add_label_notes (XVECEXP (x
, i
, j
), insn
);
5498 /* Compute transparent outgoing information for each block.
5500 An expression is transparent to an edge unless it is killed by
5501 the edge itself. This can only happen with abnormal control flow,
5502 when the edge is traversed through a call. This happens with
5503 non-local labels and exceptions.
5505 This would not be necessary if we split the edge. While this is
5506 normally impossible for abnormal critical edges, with some effort
5507 it should be possible with exception handling, since we still have
5508 control over which handler should be invoked. But due to increased
5509 EH table sizes, this may not be worthwhile. */
5512 compute_transpout ()
5518 sbitmap_vector_ones (transpout
, last_basic_block
);
5522 /* Note that flow inserted a nop a the end of basic blocks that
5523 end in call instructions for reasons other than abnormal
5525 if (GET_CODE (bb
->end
) != CALL_INSN
)
5528 for (i
= 0; i
< expr_hash_table_size
; i
++)
5529 for (expr
= expr_hash_table
[i
]; expr
; expr
= expr
->next_same_hash
)
5530 if (GET_CODE (expr
->expr
) == MEM
)
5532 if (GET_CODE (XEXP (expr
->expr
, 0)) == SYMBOL_REF
5533 && CONSTANT_POOL_ADDRESS_P (XEXP (expr
->expr
, 0)))
5536 /* ??? Optimally, we would use interprocedural alias
5537 analysis to determine if this mem is actually killed
5539 RESET_BIT (transpout
[bb
->index
], expr
->bitmap_index
);
5544 /* Removal of useless null pointer checks */
5546 /* Called via note_stores. X is set by SETTER. If X is a register we must
5547 invalidate nonnull_local and set nonnull_killed. DATA is really a
5548 `null_pointer_info *'.
5550 We ignore hard registers. */
5553 invalidate_nonnull_info (x
, setter
, data
)
5555 rtx setter ATTRIBUTE_UNUSED
;
5559 struct null_pointer_info
*npi
= (struct null_pointer_info
*) data
;
5561 while (GET_CODE (x
) == SUBREG
)
5564 /* Ignore anything that is not a register or is a hard register. */
5565 if (GET_CODE (x
) != REG
5566 || REGNO (x
) < npi
->min_reg
5567 || REGNO (x
) >= npi
->max_reg
)
5570 regno
= REGNO (x
) - npi
->min_reg
;
5572 RESET_BIT (npi
->nonnull_local
[npi
->current_block
->index
], regno
);
5573 SET_BIT (npi
->nonnull_killed
[npi
->current_block
->index
], regno
);
5576 /* Do null-pointer check elimination for the registers indicated in
5577 NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
5578 they are not our responsibility to free. */
5581 delete_null_pointer_checks_1 (block_reg
, nonnull_avin
,
5583 unsigned int *block_reg
;
5584 sbitmap
*nonnull_avin
;
5585 sbitmap
*nonnull_avout
;
5586 struct null_pointer_info
*npi
;
5588 basic_block bb
, current_block
;
5589 sbitmap
*nonnull_local
= npi
->nonnull_local
;
5590 sbitmap
*nonnull_killed
= npi
->nonnull_killed
;
5591 int something_changed
= 0;
5593 /* Compute local properties, nonnull and killed. A register will have
5594 the nonnull property if at the end of the current block its value is
5595 known to be nonnull. The killed property indicates that somewhere in
5596 the block any information we had about the register is killed.
5598 Note that a register can have both properties in a single block. That
5599 indicates that it's killed, then later in the block a new value is
5601 sbitmap_vector_zero (nonnull_local
, last_basic_block
);
5602 sbitmap_vector_zero (nonnull_killed
, last_basic_block
);
5604 FOR_EACH_BB (current_block
)
5606 rtx insn
, stop_insn
;
5608 /* Set the current block for invalidate_nonnull_info. */
5609 npi
->current_block
= current_block
;
5611 /* Scan each insn in the basic block looking for memory references and
5613 stop_insn
= NEXT_INSN (current_block
->end
);
5614 for (insn
= current_block
->head
;
5616 insn
= NEXT_INSN (insn
))
5621 /* Ignore anything that is not a normal insn. */
5622 if (! INSN_P (insn
))
5625 /* Basically ignore anything that is not a simple SET. We do have
5626 to make sure to invalidate nonnull_local and set nonnull_killed
5627 for such insns though. */
5628 set
= single_set (insn
);
5631 note_stores (PATTERN (insn
), invalidate_nonnull_info
, npi
);
5635 /* See if we've got a usable memory load. We handle it first
5636 in case it uses its address register as a dest (which kills
5637 the nonnull property). */
5638 if (GET_CODE (SET_SRC (set
)) == MEM
5639 && GET_CODE ((reg
= XEXP (SET_SRC (set
), 0))) == REG
5640 && REGNO (reg
) >= npi
->min_reg
5641 && REGNO (reg
) < npi
->max_reg
)
5642 SET_BIT (nonnull_local
[current_block
->index
],
5643 REGNO (reg
) - npi
->min_reg
);
5645 /* Now invalidate stuff clobbered by this insn. */
5646 note_stores (PATTERN (insn
), invalidate_nonnull_info
, npi
);
5648 /* And handle stores, we do these last since any sets in INSN can
5649 not kill the nonnull property if it is derived from a MEM
5650 appearing in a SET_DEST. */
5651 if (GET_CODE (SET_DEST (set
)) == MEM
5652 && GET_CODE ((reg
= XEXP (SET_DEST (set
), 0))) == REG
5653 && REGNO (reg
) >= npi
->min_reg
5654 && REGNO (reg
) < npi
->max_reg
)
5655 SET_BIT (nonnull_local
[current_block
->index
],
5656 REGNO (reg
) - npi
->min_reg
);
5660 /* Now compute global properties based on the local properties. This
5661 is a classic global availablity algorithm. */
5662 compute_available (nonnull_local
, nonnull_killed
,
5663 nonnull_avout
, nonnull_avin
);
5665 /* Now look at each bb and see if it ends with a compare of a value
5669 rtx last_insn
= bb
->end
;
5670 rtx condition
, earliest
;
5671 int compare_and_branch
;
5673 /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
5674 since BLOCK_REG[BB] is zero if this block did not end with a
5675 comparison against zero, this condition works. */
5676 if (block_reg
[bb
->index
] < npi
->min_reg
5677 || block_reg
[bb
->index
] >= npi
->max_reg
)
5680 /* LAST_INSN is a conditional jump. Get its condition. */
5681 condition
= get_condition (last_insn
, &earliest
);
5683 /* If we can't determine the condition then skip. */
5687 /* Is the register known to have a nonzero value? */
5688 if (!TEST_BIT (nonnull_avout
[bb
->index
], block_reg
[bb
->index
] - npi
->min_reg
))
5691 /* Try to compute whether the compare/branch at the loop end is one or
5692 two instructions. */
5693 if (earliest
== last_insn
)
5694 compare_and_branch
= 1;
5695 else if (earliest
== prev_nonnote_insn (last_insn
))
5696 compare_and_branch
= 2;
5700 /* We know the register in this comparison is nonnull at exit from
5701 this block. We can optimize this comparison. */
5702 if (GET_CODE (condition
) == NE
)
5706 new_jump
= emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn
)),
5708 JUMP_LABEL (new_jump
) = JUMP_LABEL (last_insn
);
5709 LABEL_NUSES (JUMP_LABEL (new_jump
))++;
5710 emit_barrier_after (new_jump
);
5713 something_changed
= 1;
5714 delete_insn (last_insn
);
5715 if (compare_and_branch
== 2)
5716 delete_insn (earliest
);
5717 purge_dead_edges (bb
);
5719 /* Don't check this block again. (Note that BLOCK_END is
5720 invalid here; we deleted the last instruction in the
5722 block_reg
[bb
->index
] = 0;
5725 return something_changed
;
5728 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
5731 This is conceptually similar to global constant/copy propagation and
5732 classic global CSE (it even uses the same dataflow equations as cprop).
5734 If a register is used as memory address with the form (mem (reg)), then we
5735 know that REG can not be zero at that point in the program. Any instruction
5736 which sets REG "kills" this property.
5738 So, if every path leading to a conditional branch has an available memory
5739 reference of that form, then we know the register can not have the value
5740 zero at the conditional branch.
5742 So we merely need to compute the local properies and propagate that data
5743 around the cfg, then optimize where possible.
5745 We run this pass two times. Once before CSE, then again after CSE. This
5746 has proven to be the most profitable approach. It is rare for new
5747 optimization opportunities of this nature to appear after the first CSE
5750 This could probably be integrated with global cprop with a little work. */
5753 delete_null_pointer_checks (f
)
5754 rtx f ATTRIBUTE_UNUSED
;
5756 sbitmap
*nonnull_avin
, *nonnull_avout
;
5757 unsigned int *block_reg
;
5762 struct null_pointer_info npi
;
5763 int something_changed
= 0;
5765 /* If we have only a single block, then there's nothing to do. */
5766 if (n_basic_blocks
<= 1)
5769 /* Trying to perform global optimizations on flow graphs which have
5770 a high connectivity will take a long time and is unlikely to be
5771 particularly useful.
5773 In normal circumstances a cfg should have about twice as many edges
5774 as blocks. But we do not want to punish small functions which have
5775 a couple switch statements. So we require a relatively large number
5776 of basic blocks and the ratio of edges to blocks to be high. */
5777 if (n_basic_blocks
> 1000 && n_edges
/ n_basic_blocks
>= 20)
5780 /* We need four bitmaps, each with a bit for each register in each
5782 max_reg
= max_reg_num ();
5783 regs_per_pass
= get_bitmap_width (4, last_basic_block
, max_reg
);
5785 /* Allocate bitmaps to hold local and global properties. */
5786 npi
.nonnull_local
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
5787 npi
.nonnull_killed
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
5788 nonnull_avin
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
5789 nonnull_avout
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
5791 /* Go through the basic blocks, seeing whether or not each block
5792 ends with a conditional branch whose condition is a comparison
5793 against zero. Record the register compared in BLOCK_REG. */
5794 block_reg
= (unsigned int *) xcalloc (last_basic_block
, sizeof (int));
5797 rtx last_insn
= bb
->end
;
5798 rtx condition
, earliest
, reg
;
5800 /* We only want conditional branches. */
5801 if (GET_CODE (last_insn
) != JUMP_INSN
5802 || !any_condjump_p (last_insn
)
5803 || !onlyjump_p (last_insn
))
5806 /* LAST_INSN is a conditional jump. Get its condition. */
5807 condition
= get_condition (last_insn
, &earliest
);
5809 /* If we were unable to get the condition, or it is not an equality
5810 comparison against zero then there's nothing we can do. */
5812 || (GET_CODE (condition
) != NE
&& GET_CODE (condition
) != EQ
)
5813 || GET_CODE (XEXP (condition
, 1)) != CONST_INT
5814 || (XEXP (condition
, 1)
5815 != CONST0_RTX (GET_MODE (XEXP (condition
, 0)))))
5818 /* We must be checking a register against zero. */
5819 reg
= XEXP (condition
, 0);
5820 if (GET_CODE (reg
) != REG
)
5823 block_reg
[bb
->index
] = REGNO (reg
);
5826 /* Go through the algorithm for each block of registers. */
5827 for (reg
= FIRST_PSEUDO_REGISTER
; reg
< max_reg
; reg
+= regs_per_pass
)
5830 npi
.max_reg
= MIN (reg
+ regs_per_pass
, max_reg
);
5831 something_changed
|= delete_null_pointer_checks_1 (block_reg
,
5837 /* Free the table of registers compared at the end of every block. */
5841 sbitmap_vector_free (npi
.nonnull_local
);
5842 sbitmap_vector_free (npi
.nonnull_killed
);
5843 sbitmap_vector_free (nonnull_avin
);
5844 sbitmap_vector_free (nonnull_avout
);
5846 return something_changed
;
5849 /* Code Hoisting variables and subroutines. */
5851 /* Very busy expressions. */
5852 static sbitmap
*hoist_vbein
;
5853 static sbitmap
*hoist_vbeout
;
5855 /* Hoistable expressions. */
5856 static sbitmap
*hoist_exprs
;
5858 /* Dominator bitmaps. */
5859 dominance_info dominators
;
5861 /* ??? We could compute post dominators and run this algorithm in
5862 reverse to to perform tail merging, doing so would probably be
5863 more effective than the tail merging code in jump.c.
5865 It's unclear if tail merging could be run in parallel with
5866 code hoisting. It would be nice. */
5868 /* Allocate vars used for code hoisting analysis. */
5871 alloc_code_hoist_mem (n_blocks
, n_exprs
)
5872 int n_blocks
, n_exprs
;
5874 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5875 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5876 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5878 hoist_vbein
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5879 hoist_vbeout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5880 hoist_exprs
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5881 transpout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5884 /* Free vars used for code hoisting analysis. */
5887 free_code_hoist_mem ()
5889 sbitmap_vector_free (antloc
);
5890 sbitmap_vector_free (transp
);
5891 sbitmap_vector_free (comp
);
5893 sbitmap_vector_free (hoist_vbein
);
5894 sbitmap_vector_free (hoist_vbeout
);
5895 sbitmap_vector_free (hoist_exprs
);
5896 sbitmap_vector_free (transpout
);
5898 free_dominance_info (dominators
);
5901 /* Compute the very busy expressions at entry/exit from each block.
5903 An expression is very busy if all paths from a given point
5904 compute the expression. */
5907 compute_code_hoist_vbeinout ()
5909 int changed
, passes
;
5912 sbitmap_vector_zero (hoist_vbeout
, last_basic_block
);
5913 sbitmap_vector_zero (hoist_vbein
, last_basic_block
);
5922 /* We scan the blocks in the reverse order to speed up
5924 FOR_EACH_BB_REVERSE (bb
)
5926 changed
|= sbitmap_a_or_b_and_c_cg (hoist_vbein
[bb
->index
], antloc
[bb
->index
],
5927 hoist_vbeout
[bb
->index
], transp
[bb
->index
]);
5928 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
5929 sbitmap_intersection_of_succs (hoist_vbeout
[bb
->index
], hoist_vbein
, bb
->index
);
5936 fprintf (gcse_file
, "hoisting vbeinout computation: %d passes\n", passes
);
5939 /* Top level routine to do the dataflow analysis needed by code hoisting. */
5942 compute_code_hoist_data ()
5944 compute_local_properties (transp
, comp
, antloc
, 0);
5945 compute_transpout ();
5946 compute_code_hoist_vbeinout ();
5947 dominators
= calculate_dominance_info (CDI_DOMINATORS
);
5949 fprintf (gcse_file
, "\n");
5952 /* Determine if the expression identified by EXPR_INDEX would
5953 reach BB unimpared if it was placed at the end of EXPR_BB.
5955 It's unclear exactly what Muchnick meant by "unimpared". It seems
5956 to me that the expression must either be computed or transparent in
5957 *every* block in the path(s) from EXPR_BB to BB. Any other definition
5958 would allow the expression to be hoisted out of loops, even if
5959 the expression wasn't a loop invariant.
5961 Contrast this to reachability for PRE where an expression is
5962 considered reachable if *any* path reaches instead of *all*
5966 hoist_expr_reaches_here_p (expr_bb
, expr_index
, bb
, visited
)
5967 basic_block expr_bb
;
5973 int visited_allocated_locally
= 0;
5976 if (visited
== NULL
)
5978 visited_allocated_locally
= 1;
5979 visited
= xcalloc (last_basic_block
, 1);
5982 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
5984 basic_block pred_bb
= pred
->src
;
5986 if (pred
->src
== ENTRY_BLOCK_PTR
)
5988 else if (pred_bb
== expr_bb
)
5990 else if (visited
[pred_bb
->index
])
5993 /* Does this predecessor generate this expression? */
5994 else if (TEST_BIT (comp
[pred_bb
->index
], expr_index
))
5996 else if (! TEST_BIT (transp
[pred_bb
->index
], expr_index
))
6002 visited
[pred_bb
->index
] = 1;
6003 if (! hoist_expr_reaches_here_p (expr_bb
, expr_index
,
6008 if (visited_allocated_locally
)
6011 return (pred
== NULL
);
6014 /* Actually perform code hoisting. */
6019 basic_block bb
, dominated
;
6021 unsigned int domby_len
;
6023 struct expr
**index_map
;
6026 sbitmap_vector_zero (hoist_exprs
, last_basic_block
);
6028 /* Compute a mapping from expression number (`bitmap_index') to
6029 hash table entry. */
6031 index_map
= (struct expr
**) xcalloc (n_exprs
, sizeof (struct expr
*));
6032 for (i
= 0; i
< expr_hash_table_size
; i
++)
6033 for (expr
= expr_hash_table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
6034 index_map
[expr
->bitmap_index
] = expr
;
6036 /* Walk over each basic block looking for potentially hoistable
6037 expressions, nothing gets hoisted from the entry block. */
6041 int insn_inserted_p
;
6043 domby_len
= get_dominated_by (dominators
, bb
, &domby
);
6044 /* Examine each expression that is very busy at the exit of this
6045 block. These are the potentially hoistable expressions. */
6046 for (i
= 0; i
< hoist_vbeout
[bb
->index
]->n_bits
; i
++)
6050 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
)
6051 && TEST_BIT (transpout
[bb
->index
], i
))
6053 /* We've found a potentially hoistable expression, now
6054 we look at every block BB dominates to see if it
6055 computes the expression. */
6056 for (j
= 0; j
< domby_len
; j
++)
6058 dominated
= domby
[j
];
6059 /* Ignore self dominance. */
6060 if (bb
== dominated
)
6062 /* We've found a dominated block, now see if it computes
6063 the busy expression and whether or not moving that
6064 expression to the "beginning" of that block is safe. */
6065 if (!TEST_BIT (antloc
[dominated
->index
], i
))
6068 /* Note if the expression would reach the dominated block
6069 unimpared if it was placed at the end of BB.
6071 Keep track of how many times this expression is hoistable
6072 from a dominated block into BB. */
6073 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
6077 /* If we found more than one hoistable occurrence of this
6078 expression, then note it in the bitmap of expressions to
6079 hoist. It makes no sense to hoist things which are computed
6080 in only one BB, and doing so tends to pessimize register
6081 allocation. One could increase this value to try harder
6082 to avoid any possible code expansion due to register
6083 allocation issues; however experiments have shown that
6084 the vast majority of hoistable expressions are only movable
6085 from two successors, so raising this threshhold is likely
6086 to nullify any benefit we get from code hoisting. */
6089 SET_BIT (hoist_exprs
[bb
->index
], i
);
6094 /* If we found nothing to hoist, then quit now. */
6101 /* Loop over all the hoistable expressions. */
6102 for (i
= 0; i
< hoist_exprs
[bb
->index
]->n_bits
; i
++)
6104 /* We want to insert the expression into BB only once, so
6105 note when we've inserted it. */
6106 insn_inserted_p
= 0;
6108 /* These tests should be the same as the tests above. */
6109 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
))
6111 /* We've found a potentially hoistable expression, now
6112 we look at every block BB dominates to see if it
6113 computes the expression. */
6114 for (j
= 0; j
< domby_len
; j
++)
6116 dominated
= domby
[j
];
6117 /* Ignore self dominance. */
6118 if (bb
== dominated
)
6121 /* We've found a dominated block, now see if it computes
6122 the busy expression and whether or not moving that
6123 expression to the "beginning" of that block is safe. */
6124 if (!TEST_BIT (antloc
[dominated
->index
], i
))
6127 /* The expression is computed in the dominated block and
6128 it would be safe to compute it at the start of the
6129 dominated block. Now we have to determine if the
6130 expression would reach the dominated block if it was
6131 placed at the end of BB. */
6132 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
6134 struct expr
*expr
= index_map
[i
];
6135 struct occr
*occr
= expr
->antic_occr
;
6139 /* Find the right occurrence of this expression. */
6140 while (BLOCK_FOR_INSN (occr
->insn
) != dominated
&& occr
)
6143 /* Should never happen. */
6149 set
= single_set (insn
);
6153 /* Create a pseudo-reg to store the result of reaching
6154 expressions into. Get the mode for the new pseudo
6155 from the mode of the original destination pseudo. */
6156 if (expr
->reaching_reg
== NULL
)
6158 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
6160 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
6162 occr
->deleted_p
= 1;
6163 if (!insn_inserted_p
)
6165 insert_insn_end_bb (index_map
[i
], bb
, 0);
6166 insn_inserted_p
= 1;
6178 /* Top level routine to perform one code hoisting (aka unification) pass
6180 Return non-zero if a change was made. */
6183 one_code_hoisting_pass ()
6187 alloc_expr_hash_table (max_cuid
);
6188 compute_expr_hash_table ();
6190 dump_hash_table (gcse_file
, "Code Hosting Expressions", expr_hash_table
,
6191 expr_hash_table_size
, n_exprs
);
6195 alloc_code_hoist_mem (last_basic_block
, n_exprs
);
6196 compute_code_hoist_data ();
6198 free_code_hoist_mem ();
6201 free_expr_hash_table ();
6206 /* Here we provide the things required to do store motion towards
6207 the exit. In order for this to be effective, gcse also needed to
6208 be taught how to move a load when it is kill only by a store to itself.
6213 void foo(float scale)
6215 for (i=0; i<10; i++)
6219 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
6220 the load out since its live around the loop, and stored at the bottom
6223 The 'Load Motion' referred to and implemented in this file is
6224 an enhancement to gcse which when using edge based lcm, recognizes
6225 this situation and allows gcse to move the load out of the loop.
6227 Once gcse has hoisted the load, store motion can then push this
6228 load towards the exit, and we end up with no loads or stores of 'i'
6231 /* This will search the ldst list for a matching expression. If it
6232 doesn't find one, we create one and initialize it. */
6234 static struct ls_expr
*
6238 struct ls_expr
* ptr
;
6240 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6241 if (expr_equiv_p (ptr
->pattern
, x
))
6246 ptr
= (struct ls_expr
*) xmalloc (sizeof (struct ls_expr
));
6248 ptr
->next
= pre_ldst_mems
;
6251 ptr
->loads
= NULL_RTX
;
6252 ptr
->stores
= NULL_RTX
;
6253 ptr
->reaching_reg
= NULL_RTX
;
6256 ptr
->hash_index
= 0;
6257 pre_ldst_mems
= ptr
;
6263 /* Free up an individual ldst entry. */
6266 free_ldst_entry (ptr
)
6267 struct ls_expr
* ptr
;
6269 free_INSN_LIST_list (& ptr
->loads
);
6270 free_INSN_LIST_list (& ptr
->stores
);
6275 /* Free up all memory associated with the ldst list. */
6280 while (pre_ldst_mems
)
6282 struct ls_expr
* tmp
= pre_ldst_mems
;
6284 pre_ldst_mems
= pre_ldst_mems
->next
;
6286 free_ldst_entry (tmp
);
6289 pre_ldst_mems
= NULL
;
6292 /* Dump debugging info about the ldst list. */
6295 print_ldst_list (file
)
6298 struct ls_expr
* ptr
;
6300 fprintf (file
, "LDST list: \n");
6302 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6304 fprintf (file
, " Pattern (%3d): ", ptr
->index
);
6306 print_rtl (file
, ptr
->pattern
);
6308 fprintf (file
, "\n Loads : ");
6311 print_rtl (file
, ptr
->loads
);
6313 fprintf (file
, "(nil)");
6315 fprintf (file
, "\n Stores : ");
6318 print_rtl (file
, ptr
->stores
);
6320 fprintf (file
, "(nil)");
6322 fprintf (file
, "\n\n");
6325 fprintf (file
, "\n");
6328 /* Returns 1 if X is in the list of ldst only expressions. */
6330 static struct ls_expr
*
6331 find_rtx_in_ldst (x
)
6334 struct ls_expr
* ptr
;
6336 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
6337 if (expr_equiv_p (ptr
->pattern
, x
) && ! ptr
->invalid
)
6343 /* Assign each element of the list of mems a monotonically increasing value. */
6348 struct ls_expr
* ptr
;
6351 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
6357 /* Return first item in the list. */
6359 static inline struct ls_expr
*
6362 return pre_ldst_mems
;
6365 /* Return the next item in ther list after the specified one. */
6367 static inline struct ls_expr
*
6369 struct ls_expr
* ptr
;
6374 /* Load Motion for loads which only kill themselves. */
6376 /* Return true if x is a simple MEM operation, with no registers or
6377 side effects. These are the types of loads we consider for the
6378 ld_motion list, otherwise we let the usual aliasing take care of it. */
6384 if (GET_CODE (x
) != MEM
)
6387 if (MEM_VOLATILE_P (x
))
6390 if (GET_MODE (x
) == BLKmode
)
6393 if (!rtx_varies_p (XEXP (x
, 0), 0))
6399 /* Make sure there isn't a buried reference in this pattern anywhere.
6400 If there is, invalidate the entry for it since we're not capable
6401 of fixing it up just yet.. We have to be sure we know about ALL
6402 loads since the aliasing code will allow all entries in the
6403 ld_motion list to not-alias itself. If we miss a load, we will get
6404 the wrong value since gcse might common it and we won't know to
6408 invalidate_any_buried_refs (x
)
6413 struct ls_expr
* ptr
;
6415 /* Invalidate it in the list. */
6416 if (GET_CODE (x
) == MEM
&& simple_mem (x
))
6418 ptr
= ldst_entry (x
);
6422 /* Recursively process the insn. */
6423 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
6425 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0; i
--)
6428 invalidate_any_buried_refs (XEXP (x
, i
));
6429 else if (fmt
[i
] == 'E')
6430 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
6431 invalidate_any_buried_refs (XVECEXP (x
, i
, j
));
6435 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
6436 being defined as MEM loads and stores to symbols, with no
6437 side effects and no registers in the expression. If there are any
6438 uses/defs which don't match this criteria, it is invalidated and
6439 trimmed out later. */
6442 compute_ld_motion_mems ()
6444 struct ls_expr
* ptr
;
6448 pre_ldst_mems
= NULL
;
6452 for (insn
= bb
->head
;
6453 insn
&& insn
!= NEXT_INSN (bb
->end
);
6454 insn
= NEXT_INSN (insn
))
6456 if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i')
6458 if (GET_CODE (PATTERN (insn
)) == SET
)
6460 rtx src
= SET_SRC (PATTERN (insn
));
6461 rtx dest
= SET_DEST (PATTERN (insn
));
6463 /* Check for a simple LOAD... */
6464 if (GET_CODE (src
) == MEM
&& simple_mem (src
))
6466 ptr
= ldst_entry (src
);
6467 if (GET_CODE (dest
) == REG
)
6468 ptr
->loads
= alloc_INSN_LIST (insn
, ptr
->loads
);
6474 /* Make sure there isn't a buried load somewhere. */
6475 invalidate_any_buried_refs (src
);
6478 /* Check for stores. Don't worry about aliased ones, they
6479 will block any movement we might do later. We only care
6480 about this exact pattern since those are the only
6481 circumstance that we will ignore the aliasing info. */
6482 if (GET_CODE (dest
) == MEM
&& simple_mem (dest
))
6484 ptr
= ldst_entry (dest
);
6486 if (GET_CODE (src
) != MEM
6487 && GET_CODE (src
) != ASM_OPERANDS
)
6488 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
6494 invalidate_any_buried_refs (PATTERN (insn
));
6500 /* Remove any references that have been either invalidated or are not in the
6501 expression list for pre gcse. */
6504 trim_ld_motion_mems ()
6506 struct ls_expr
* last
= NULL
;
6507 struct ls_expr
* ptr
= first_ls_expr ();
6511 int del
= ptr
->invalid
;
6512 struct expr
* expr
= NULL
;
6514 /* Delete if entry has been made invalid. */
6520 /* Delete if we cannot find this mem in the expression list. */
6521 for (i
= 0; i
< expr_hash_table_size
&& del
; i
++)
6523 for (expr
= expr_hash_table
[i
];
6525 expr
= expr
->next_same_hash
)
6526 if (expr_equiv_p (expr
->expr
, ptr
->pattern
))
6538 last
->next
= ptr
->next
;
6539 free_ldst_entry (ptr
);
6544 pre_ldst_mems
= pre_ldst_mems
->next
;
6545 free_ldst_entry (ptr
);
6546 ptr
= pre_ldst_mems
;
6551 /* Set the expression field if we are keeping it. */
6558 /* Show the world what we've found. */
6559 if (gcse_file
&& pre_ldst_mems
!= NULL
)
6560 print_ldst_list (gcse_file
);
6563 /* This routine will take an expression which we are replacing with
6564 a reaching register, and update any stores that are needed if
6565 that expression is in the ld_motion list. Stores are updated by
6566 copying their SRC to the reaching register, and then storeing
6567 the reaching register into the store location. These keeps the
6568 correct value in the reaching register for the loads. */
6571 update_ld_motion_stores (expr
)
6574 struct ls_expr
* mem_ptr
;
6576 if ((mem_ptr
= find_rtx_in_ldst (expr
->expr
)))
6578 /* We can try to find just the REACHED stores, but is shouldn't
6579 matter to set the reaching reg everywhere... some might be
6580 dead and should be eliminated later. */
6582 /* We replace SET mem = expr with
6584 SET mem = reg , where reg is the
6585 reaching reg used in the load. */
6586 rtx list
= mem_ptr
->stores
;
6588 for ( ; list
!= NULL_RTX
; list
= XEXP (list
, 1))
6590 rtx insn
= XEXP (list
, 0);
6591 rtx pat
= PATTERN (insn
);
6592 rtx src
= SET_SRC (pat
);
6593 rtx reg
= expr
->reaching_reg
;
6596 /* If we've already copied it, continue. */
6597 if (expr
->reaching_reg
== src
)
6602 fprintf (gcse_file
, "PRE: store updated with reaching reg ");
6603 print_rtl (gcse_file
, expr
->reaching_reg
);
6604 fprintf (gcse_file
, ":\n ");
6605 print_inline_rtx (gcse_file
, insn
, 8);
6606 fprintf (gcse_file
, "\n");
6609 copy
= gen_move_insn ( reg
, SET_SRC (pat
));
6610 new = emit_insn_before (copy
, insn
);
6611 record_one_set (REGNO (reg
), new);
6612 SET_SRC (pat
) = reg
;
6614 /* un-recognize this pattern since it's probably different now. */
6615 INSN_CODE (insn
) = -1;
6616 gcse_create_count
++;
6621 /* Store motion code. */
6623 /* This is used to communicate the target bitvector we want to use in the
6624 reg_set_info routine when called via the note_stores mechanism. */
6625 static sbitmap
* regvec
;
6627 /* Used in computing the reverse edge graph bit vectors. */
6628 static sbitmap
* st_antloc
;
6630 /* Global holding the number of store expressions we are dealing with. */
6631 static int num_stores
;
6633 /* Checks to set if we need to mark a register set. Called from note_stores. */
6636 reg_set_info (dest
, setter
, data
)
6637 rtx dest
, setter ATTRIBUTE_UNUSED
;
6638 void * data ATTRIBUTE_UNUSED
;
6640 if (GET_CODE (dest
) == SUBREG
)
6641 dest
= SUBREG_REG (dest
);
6643 if (GET_CODE (dest
) == REG
)
6644 SET_BIT (*regvec
, REGNO (dest
));
6647 /* Return non-zero if the register operands of expression X are killed
6648 anywhere in basic block BB. */
6651 store_ops_ok (x
, bb
)
6659 /* Repeat is used to turn tail-recursion into iteration. */
6665 code
= GET_CODE (x
);
6669 /* If a reg has changed after us in this
6670 block, the operand has been killed. */
6671 return TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
));
6699 i
= GET_RTX_LENGTH (code
) - 1;
6700 fmt
= GET_RTX_FORMAT (code
);
6706 rtx tem
= XEXP (x
, i
);
6708 /* If we are about to do the last recursive call
6709 needed at this level, change it into iteration.
6710 This function is called enough to be worth it. */
6717 if (! store_ops_ok (tem
, bb
))
6720 else if (fmt
[i
] == 'E')
6724 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
6726 if (! store_ops_ok (XVECEXP (x
, i
, j
), bb
))
6735 /* Determine whether insn is MEM store pattern that we will consider moving. */
6738 find_moveable_store (insn
)
6741 struct ls_expr
* ptr
;
6742 rtx dest
= PATTERN (insn
);
6744 if (GET_CODE (dest
) != SET
6745 || GET_CODE (SET_SRC (dest
)) == ASM_OPERANDS
)
6748 dest
= SET_DEST (dest
);
6750 if (GET_CODE (dest
) != MEM
|| MEM_VOLATILE_P (dest
)
6751 || GET_MODE (dest
) == BLKmode
)
6754 if (GET_CODE (XEXP (dest
, 0)) != SYMBOL_REF
)
6757 if (rtx_varies_p (XEXP (dest
, 0), 0))
6760 ptr
= ldst_entry (dest
);
6761 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
6764 /* Perform store motion. Much like gcse, except we move expressions the
6765 other way by looking at the flowgraph in reverse. */
6768 compute_store_table ()
6775 max_gcse_regno
= max_reg_num ();
6777 reg_set_in_block
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
,
6779 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
6782 /* Find all the stores we care about. */
6785 regvec
= & (reg_set_in_block
[bb
->index
]);
6786 for (insn
= bb
->end
;
6787 insn
&& insn
!= PREV_INSN (bb
->end
);
6788 insn
= PREV_INSN (insn
))
6790 /* Ignore anything that is not a normal insn. */
6791 if (! INSN_P (insn
))
6794 if (GET_CODE (insn
) == CALL_INSN
)
6796 bool clobbers_all
= false;
6797 #ifdef NON_SAVING_SETJMP
6798 if (NON_SAVING_SETJMP
6799 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
6800 clobbers_all
= true;
6803 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
6805 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
6806 SET_BIT (reg_set_in_block
[bb
->index
], regno
);
6809 pat
= PATTERN (insn
);
6810 note_stores (pat
, reg_set_info
, NULL
);
6812 /* Now that we've marked regs, look for stores. */
6813 if (GET_CODE (pat
) == SET
)
6814 find_moveable_store (insn
);
6818 ret
= enumerate_ldsts ();
6822 fprintf (gcse_file
, "Store Motion Expressions.\n");
6823 print_ldst_list (gcse_file
);
6829 /* Check to see if the load X is aliased with STORE_PATTERN. */
6832 load_kills_store (x
, store_pattern
)
6833 rtx x
, store_pattern
;
6835 if (true_dependence (x
, GET_MODE (x
), store_pattern
, rtx_addr_varies_p
))
6840 /* Go through the entire insn X, looking for any loads which might alias
6841 STORE_PATTERN. Return 1 if found. */
6844 find_loads (x
, store_pattern
)
6845 rtx x
, store_pattern
;
6854 if (GET_CODE (x
) == SET
)
6857 if (GET_CODE (x
) == MEM
)
6859 if (load_kills_store (x
, store_pattern
))
6863 /* Recursively process the insn. */
6864 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
6866 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0 && !ret
; i
--)
6869 ret
|= find_loads (XEXP (x
, i
), store_pattern
);
6870 else if (fmt
[i
] == 'E')
6871 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
6872 ret
|= find_loads (XVECEXP (x
, i
, j
), store_pattern
);
6877 /* Check if INSN kills the store pattern X (is aliased with it).
6878 Return 1 if it it does. */
6881 store_killed_in_insn (x
, insn
)
6884 if (GET_RTX_CLASS (GET_CODE (insn
)) != 'i')
6887 if (GET_CODE (insn
) == CALL_INSN
)
6889 /* A normal or pure call might read from pattern,
6890 but a const call will not. */
6891 return ! CONST_OR_PURE_CALL_P (insn
) || pure_call_p (insn
);
6894 if (GET_CODE (PATTERN (insn
)) == SET
)
6896 rtx pat
= PATTERN (insn
);
6897 /* Check for memory stores to aliased objects. */
6898 if (GET_CODE (SET_DEST (pat
)) == MEM
&& !expr_equiv_p (SET_DEST (pat
), x
))
6899 /* pretend its a load and check for aliasing. */
6900 if (find_loads (SET_DEST (pat
), x
))
6902 return find_loads (SET_SRC (pat
), x
);
6905 return find_loads (PATTERN (insn
), x
);
6908 /* Returns 1 if the expression X is loaded or clobbered on or after INSN
6909 within basic block BB. */
6912 store_killed_after (x
, insn
, bb
)
6921 /* Check if the register operands of the store are OK in this block.
6922 Note that if registers are changed ANYWHERE in the block, we'll
6923 decide we can't move it, regardless of whether it changed above
6924 or below the store. This could be improved by checking the register
6925 operands while lookinng for aliasing in each insn. */
6926 if (!store_ops_ok (XEXP (x
, 0), bb
))
6929 for ( ; insn
&& insn
!= NEXT_INSN (last
); insn
= NEXT_INSN (insn
))
6930 if (store_killed_in_insn (x
, insn
))
6936 /* Returns 1 if the expression X is loaded or clobbered on or before INSN
6937 within basic block BB. */
6939 store_killed_before (x
, insn
, bb
)
6943 rtx first
= bb
->head
;
6946 return store_killed_in_insn (x
, insn
);
6948 /* Check if the register operands of the store are OK in this block.
6949 Note that if registers are changed ANYWHERE in the block, we'll
6950 decide we can't move it, regardless of whether it changed above
6951 or below the store. This could be improved by checking the register
6952 operands while lookinng for aliasing in each insn. */
6953 if (!store_ops_ok (XEXP (x
, 0), bb
))
6956 for ( ; insn
&& insn
!= PREV_INSN (first
); insn
= PREV_INSN (insn
))
6957 if (store_killed_in_insn (x
, insn
))
6963 #define ANTIC_STORE_LIST(x) ((x)->loads)
6964 #define AVAIL_STORE_LIST(x) ((x)->stores)
6966 /* Given the table of available store insns at the end of blocks,
6967 determine which ones are not killed by aliasing, and generate
6968 the appropriate vectors for gen and killed. */
6970 build_store_vectors ()
6974 struct ls_expr
* ptr
;
6976 /* Build the gen_vector. This is any store in the table which is not killed
6977 by aliasing later in its block. */
6978 ae_gen
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
6979 sbitmap_vector_zero (ae_gen
, last_basic_block
);
6981 st_antloc
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
6982 sbitmap_vector_zero (st_antloc
, last_basic_block
);
6984 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6986 /* Put all the stores into either the antic list, or the avail list,
6988 rtx store_list
= ptr
->stores
;
6989 ptr
->stores
= NULL_RTX
;
6991 for (st
= store_list
; st
!= NULL
; st
= XEXP (st
, 1))
6993 insn
= XEXP (st
, 0);
6994 bb
= BLOCK_FOR_INSN (insn
);
6996 if (!store_killed_after (ptr
->pattern
, insn
, bb
))
6998 /* If we've already seen an availale expression in this block,
6999 we can delete the one we saw already (It occurs earlier in
7000 the block), and replace it with this one). We'll copy the
7001 old SRC expression to an unused register in case there
7002 are any side effects. */
7003 if (TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
7005 /* Find previous store. */
7007 for (st
= AVAIL_STORE_LIST (ptr
); st
; st
= XEXP (st
, 1))
7008 if (BLOCK_FOR_INSN (XEXP (st
, 0)) == bb
)
7012 rtx r
= gen_reg_rtx (GET_MODE (ptr
->pattern
));
7014 fprintf (gcse_file
, "Removing redundant store:\n");
7015 replace_store_insn (r
, XEXP (st
, 0), bb
);
7016 XEXP (st
, 0) = insn
;
7020 SET_BIT (ae_gen
[bb
->index
], ptr
->index
);
7021 AVAIL_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
,
7022 AVAIL_STORE_LIST (ptr
));
7025 if (!store_killed_before (ptr
->pattern
, insn
, bb
))
7027 SET_BIT (st_antloc
[BLOCK_NUM (insn
)], ptr
->index
);
7028 ANTIC_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
,
7029 ANTIC_STORE_LIST (ptr
));
7033 /* Free the original list of store insns. */
7034 free_INSN_LIST_list (&store_list
);
7037 ae_kill
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7038 sbitmap_vector_zero (ae_kill
, last_basic_block
);
7040 transp
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7041 sbitmap_vector_zero (transp
, last_basic_block
);
7043 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7046 if (store_killed_after (ptr
->pattern
, b
->head
, b
))
7048 /* The anticipatable expression is not killed if it's gen'd. */
7050 We leave this check out for now. If we have a code sequence
7051 in a block which looks like:
7055 We should flag this as having an ANTIC expression, NOT
7056 transparent, NOT killed, and AVAIL.
7057 Unfortunately, since we haven't re-written all loads to
7058 use the reaching reg, we'll end up doing an incorrect
7059 Load in the middle here if we push the store down. It happens in
7060 gcc.c-torture/execute/960311-1.c with -O3
7061 If we always kill it in this case, we'll sometimes do
7062 uneccessary work, but it shouldn't actually hurt anything.
7063 if (!TEST_BIT (ae_gen[b], ptr->index)). */
7064 SET_BIT (ae_kill
[b
->index
], ptr
->index
);
7067 SET_BIT (transp
[b
->index
], ptr
->index
);
7070 /* Any block with no exits calls some non-returning function, so
7071 we better mark the store killed here, or we might not store to
7072 it at all. If we knew it was abort, we wouldn't have to store,
7073 but we don't know that for sure. */
7076 fprintf (gcse_file
, "ST_avail and ST_antic (shown under loads..)\n");
7077 print_ldst_list (gcse_file
);
7078 dump_sbitmap_vector (gcse_file
, "st_antloc", "", st_antloc
, last_basic_block
);
7079 dump_sbitmap_vector (gcse_file
, "st_kill", "", ae_kill
, last_basic_block
);
7080 dump_sbitmap_vector (gcse_file
, "Transpt", "", transp
, last_basic_block
);
7081 dump_sbitmap_vector (gcse_file
, "st_avloc", "", ae_gen
, last_basic_block
);
7085 /* Insert an instruction at the begining of a basic block, and update
7086 the BLOCK_HEAD if needed. */
7089 insert_insn_start_bb (insn
, bb
)
7093 /* Insert at start of successor block. */
7094 rtx prev
= PREV_INSN (bb
->head
);
7095 rtx before
= bb
->head
;
7098 if (GET_CODE (before
) != CODE_LABEL
7099 && (GET_CODE (before
) != NOTE
7100 || NOTE_LINE_NUMBER (before
) != NOTE_INSN_BASIC_BLOCK
))
7103 if (prev
== bb
->end
)
7105 before
= NEXT_INSN (before
);
7108 insn
= emit_insn_after (insn
, prev
);
7112 fprintf (gcse_file
, "STORE_MOTION insert store at start of BB %d:\n",
7114 print_inline_rtx (gcse_file
, insn
, 6);
7115 fprintf (gcse_file
, "\n");
7119 /* This routine will insert a store on an edge. EXPR is the ldst entry for
7120 the memory reference, and E is the edge to insert it on. Returns non-zero
7121 if an edge insertion was performed. */
7124 insert_store (expr
, e
)
7125 struct ls_expr
* expr
;
7132 /* We did all the deleted before this insert, so if we didn't delete a
7133 store, then we haven't set the reaching reg yet either. */
7134 if (expr
->reaching_reg
== NULL_RTX
)
7137 reg
= expr
->reaching_reg
;
7138 insn
= gen_move_insn (expr
->pattern
, reg
);
7140 /* If we are inserting this expression on ALL predecessor edges of a BB,
7141 insert it at the start of the BB, and reset the insert bits on the other
7142 edges so we don't try to insert it on the other edges. */
7144 for (tmp
= e
->dest
->pred
; tmp
; tmp
= tmp
->pred_next
)
7146 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
7147 if (index
== EDGE_INDEX_NO_EDGE
)
7149 if (! TEST_BIT (pre_insert_map
[index
], expr
->index
))
7153 /* If tmp is NULL, we found an insertion on every edge, blank the
7154 insertion vector for these edges, and insert at the start of the BB. */
7155 if (!tmp
&& bb
!= EXIT_BLOCK_PTR
)
7157 for (tmp
= e
->dest
->pred
; tmp
; tmp
= tmp
->pred_next
)
7159 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
7160 RESET_BIT (pre_insert_map
[index
], expr
->index
);
7162 insert_insn_start_bb (insn
, bb
);
7166 /* We can't insert on this edge, so we'll insert at the head of the
7167 successors block. See Morgan, sec 10.5. */
7168 if ((e
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
7170 insert_insn_start_bb (insn
, bb
);
7174 insert_insn_on_edge (insn
, e
);
7178 fprintf (gcse_file
, "STORE_MOTION insert insn on edge (%d, %d):\n",
7179 e
->src
->index
, e
->dest
->index
);
7180 print_inline_rtx (gcse_file
, insn
, 6);
7181 fprintf (gcse_file
, "\n");
7187 /* This routine will replace a store with a SET to a specified register. */
7190 replace_store_insn (reg
, del
, bb
)
7196 insn
= gen_move_insn (reg
, SET_SRC (PATTERN (del
)));
7197 insn
= emit_insn_after (insn
, del
);
7202 "STORE_MOTION delete insn in BB %d:\n ", bb
->index
);
7203 print_inline_rtx (gcse_file
, del
, 6);
7204 fprintf (gcse_file
, "\nSTORE MOTION replaced with insn:\n ");
7205 print_inline_rtx (gcse_file
, insn
, 6);
7206 fprintf (gcse_file
, "\n");
7213 /* Delete a store, but copy the value that would have been stored into
7214 the reaching_reg for later storing. */
7217 delete_store (expr
, bb
)
7218 struct ls_expr
* expr
;
7223 if (expr
->reaching_reg
== NULL_RTX
)
7224 expr
->reaching_reg
= gen_reg_rtx (GET_MODE (expr
->pattern
));
7227 /* If there is more than 1 store, the earlier ones will be dead,
7228 but it doesn't hurt to replace them here. */
7229 reg
= expr
->reaching_reg
;
7231 for (i
= AVAIL_STORE_LIST (expr
); i
; i
= XEXP (i
, 1))
7234 if (BLOCK_FOR_INSN (del
) == bb
)
7236 /* We know there is only one since we deleted redundant
7237 ones during the available computation. */
7238 replace_store_insn (reg
, del
, bb
);
7244 /* Free memory used by store motion. */
7247 free_store_memory ()
7252 sbitmap_vector_free (ae_gen
);
7254 sbitmap_vector_free (ae_kill
);
7256 sbitmap_vector_free (transp
);
7258 sbitmap_vector_free (st_antloc
);
7260 sbitmap_vector_free (pre_insert_map
);
7262 sbitmap_vector_free (pre_delete_map
);
7263 if (reg_set_in_block
)
7264 sbitmap_vector_free (reg_set_in_block
);
7266 ae_gen
= ae_kill
= transp
= st_antloc
= NULL
;
7267 pre_insert_map
= pre_delete_map
= reg_set_in_block
= NULL
;
7270 /* Perform store motion. Much like gcse, except we move expressions the
7271 other way by looking at the flowgraph in reverse. */
7278 struct ls_expr
* ptr
;
7279 int update_flow
= 0;
7283 fprintf (gcse_file
, "before store motion\n");
7284 print_rtl (gcse_file
, get_insns ());
7288 init_alias_analysis ();
7290 /* Find all the stores that are live to the end of their block. */
7291 num_stores
= compute_store_table ();
7292 if (num_stores
== 0)
7294 sbitmap_vector_free (reg_set_in_block
);
7295 end_alias_analysis ();
7299 /* Now compute whats actually available to move. */
7300 add_noreturn_fake_exit_edges ();
7301 build_store_vectors ();
7303 edge_list
= pre_edge_rev_lcm (gcse_file
, num_stores
, transp
, ae_gen
,
7304 st_antloc
, ae_kill
, &pre_insert_map
,
7307 /* Now we want to insert the new stores which are going to be needed. */
7308 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7311 if (TEST_BIT (pre_delete_map
[bb
->index
], ptr
->index
))
7312 delete_store (ptr
, bb
);
7314 for (x
= 0; x
< NUM_EDGES (edge_list
); x
++)
7315 if (TEST_BIT (pre_insert_map
[x
], ptr
->index
))
7316 update_flow
|= insert_store (ptr
, INDEX_EDGE (edge_list
, x
));
7320 commit_edge_insertions ();
7322 free_store_memory ();
7323 free_edge_list (edge_list
);
7324 remove_fake_edges ();
7325 end_alias_analysis ();
7328 #include "gt-gcse.h"