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"
169 /* Propagate flow information through back edges and thus enable PRE's
170 moving loop invariant calculations out of loops.
172 Originally this tended to create worse overall code, but several
173 improvements during the development of PRE seem to have made following
174 back edges generally a win.
176 Note much of the loop invariant code motion done here would normally
177 be done by loop.c, which has more heuristics for when to move invariants
178 out of loops. At some point we might need to move some of those
179 heuristics into gcse.c. */
181 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
182 are a superset of those done by GCSE.
184 We perform the following steps:
186 1) Compute basic block information.
188 2) Compute table of places where registers are set.
190 3) Perform copy/constant propagation.
192 4) Perform global cse.
194 5) Perform another pass of copy/constant propagation.
196 Two passes of copy/constant propagation are done because the first one
197 enables more GCSE and the second one helps to clean up the copies that
198 GCSE creates. This is needed more for PRE than for Classic because Classic
199 GCSE will try to use an existing register containing the common
200 subexpression rather than create a new one. This is harder to do for PRE
201 because of the code motion (which Classic GCSE doesn't do).
203 Expressions we are interested in GCSE-ing are of the form
204 (set (pseudo-reg) (expression)).
205 Function want_to_gcse_p says what these are.
207 PRE handles moving invariant expressions out of loops (by treating them as
208 partially redundant).
210 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
211 assignment) based GVN (global value numbering). L. T. Simpson's paper
212 (Rice University) on value numbering is a useful reference for this.
214 **********************
216 We used to support multiple passes but there are diminishing returns in
217 doing so. The first pass usually makes 90% of the changes that are doable.
218 A second pass can make a few more changes made possible by the first pass.
219 Experiments show any further passes don't make enough changes to justify
222 A study of spec92 using an unlimited number of passes:
223 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
224 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
225 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
227 It was found doing copy propagation between each pass enables further
230 PRE is quite expensive in complicated functions because the DFA can take
231 awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can
232 be modified if one wants to experiment.
234 **********************
236 The steps for PRE are:
238 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
240 2) Perform the data flow analysis for PRE.
242 3) Delete the redundant instructions
244 4) Insert the required copies [if any] that make the partially
245 redundant instructions fully redundant.
247 5) For other reaching expressions, insert an instruction to copy the value
248 to a newly created pseudo that will reach the redundant instruction.
250 The deletion is done first so that when we do insertions we
251 know which pseudo reg to use.
253 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
254 argue it is not. The number of iterations for the algorithm to converge
255 is typically 2-4 so I don't view it as that expensive (relatively speaking).
257 PRE GCSE depends heavily on the second CSE pass to clean up the copies
258 we create. To make an expression reach the place where it's redundant,
259 the result of the expression is copied to a new register, and the redundant
260 expression is deleted by replacing it with this new register. Classic GCSE
261 doesn't have this problem as much as it computes the reaching defs of
262 each register in each block and thus can try to use an existing register.
264 **********************
266 A fair bit of simplicity is created by creating small functions for simple
267 tasks, even when the function is only called in one place. This may
268 measurably slow things down [or may not] by creating more function call
269 overhead than is necessary. The source is laid out so that it's trivial
270 to make the affected functions inline so that one can measure what speed
271 up, if any, can be achieved, and maybe later when things settle things can
274 Help stamp out big monolithic functions! */
276 /* GCSE global vars. */
279 static FILE *gcse_file
;
281 /* Note whether or not we should run jump optimization after gcse. We
282 want to do this for two cases.
284 * If we changed any jumps via cprop.
286 * If we added any labels via edge splitting. */
288 static int run_jump_opt_after_gcse
;
290 /* Bitmaps are normally not included in debugging dumps.
291 However it's useful to be able to print them from GDB.
292 We could create special functions for this, but it's simpler to
293 just allow passing stderr to the dump_foo fns. Since stderr can
294 be a macro, we store a copy here. */
295 static FILE *debug_stderr
;
297 /* An obstack for our working variables. */
298 static struct obstack gcse_obstack
;
300 /* Non-zero for each mode that supports (set (reg) (reg)).
301 This is trivially true for integer and floating point values.
302 It may or may not be true for condition codes. */
303 static char can_copy_p
[(int) NUM_MACHINE_MODES
];
305 /* Non-zero if can_copy_p has been initialized. */
306 static int can_copy_init_p
;
308 struct reg_use
{rtx reg_rtx
; };
310 /* Hash table of expressions. */
314 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
316 /* Index in the available expression bitmaps. */
318 /* Next entry with the same hash. */
319 struct expr
*next_same_hash
;
320 /* List of anticipatable occurrences in basic blocks in the function.
321 An "anticipatable occurrence" is one that is the first occurrence in the
322 basic block, the operands are not modified in the basic block prior
323 to the occurrence and the output is not used between the start of
324 the block and the occurrence. */
325 struct occr
*antic_occr
;
326 /* List of available occurrence in basic blocks in the function.
327 An "available occurrence" is one that is the last occurrence in the
328 basic block and the operands are not modified by following statements in
329 the basic block [including this insn]. */
330 struct occr
*avail_occr
;
331 /* Non-null if the computation is PRE redundant.
332 The value is the newly created pseudo-reg to record a copy of the
333 expression in all the places that reach the redundant copy. */
337 /* Occurrence of an expression.
338 There is one per basic block. If a pattern appears more than once the
339 last appearance is used [or first for anticipatable expressions]. */
343 /* Next occurrence of this expression. */
345 /* The insn that computes the expression. */
347 /* Non-zero if this [anticipatable] occurrence has been deleted. */
349 /* Non-zero if this [available] occurrence has been copied to
351 /* ??? This is mutually exclusive with deleted_p, so they could share
356 /* Expression and copy propagation hash tables.
357 Each hash table is an array of buckets.
358 ??? It is known that if it were an array of entries, structure elements
359 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
360 not clear whether in the final analysis a sufficient amount of memory would
361 be saved as the size of the available expression bitmaps would be larger
362 [one could build a mapping table without holes afterwards though].
363 Someday I'll perform the computation and figure it out. */
365 /* Total size of the expression hash table, in elements. */
366 static unsigned int expr_hash_table_size
;
369 This is an array of `expr_hash_table_size' elements. */
370 static struct expr
**expr_hash_table
;
372 /* Total size of the copy propagation hash table, in elements. */
373 static unsigned int set_hash_table_size
;
376 This is an array of `set_hash_table_size' elements. */
377 static struct expr
**set_hash_table
;
379 /* Mapping of uids to cuids.
380 Only real insns get cuids. */
381 static int *uid_cuid
;
383 /* Highest UID in UID_CUID. */
386 /* Get the cuid of an insn. */
387 #ifdef ENABLE_CHECKING
388 #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
390 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
393 /* Number of cuids. */
396 /* Mapping of cuids to insns. */
397 static rtx
*cuid_insn
;
399 /* Get insn from cuid. */
400 #define CUID_INSN(CUID) (cuid_insn[CUID])
402 /* Maximum register number in function prior to doing gcse + 1.
403 Registers created during this pass have regno >= max_gcse_regno.
404 This is named with "gcse" to not collide with global of same name. */
405 static unsigned int max_gcse_regno
;
407 /* Maximum number of cse-able expressions found. */
410 /* Maximum number of assignments for copy propagation found. */
413 /* Table of registers that are modified.
415 For each register, each element is a list of places where the pseudo-reg
418 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
419 requires knowledge of which blocks kill which regs [and thus could use
420 a bitmap instead of the lists `reg_set_table' uses].
422 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
423 num-regs) [however perhaps it may be useful to keep the data as is]. One
424 advantage of recording things this way is that `reg_set_table' is fairly
425 sparse with respect to pseudo regs but for hard regs could be fairly dense
426 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
427 up functions like compute_transp since in the case of pseudo-regs we only
428 need to iterate over the number of times a pseudo-reg is set, not over the
429 number of basic blocks [clearly there is a bit of a slow down in the cases
430 where a pseudo is set more than once in a block, however it is believed
431 that the net effect is to speed things up]. This isn't done for hard-regs
432 because recording call-clobbered hard-regs in `reg_set_table' at each
433 function call can consume a fair bit of memory, and iterating over
434 hard-regs stored this way in compute_transp will be more expensive. */
436 typedef struct reg_set
438 /* The next setting of this register. */
439 struct reg_set
*next
;
440 /* The insn where it was set. */
444 static reg_set
**reg_set_table
;
446 /* Size of `reg_set_table'.
447 The table starts out at max_gcse_regno + slop, and is enlarged as
449 static int reg_set_table_size
;
451 /* Amount to grow `reg_set_table' by when it's full. */
452 #define REG_SET_TABLE_SLOP 100
454 /* This is a list of expressions which are MEMs and will be used by load
456 Load motion tracks MEMs which aren't killed by
457 anything except itself. (ie, loads and stores to a single location).
458 We can then allow movement of these MEM refs with a little special
459 allowance. (all stores copy the same value to the reaching reg used
460 for the loads). This means all values used to store into memory must have
461 no side effects so we can re-issue the setter value.
462 Store Motion uses this structure as an expression table to track stores
463 which look interesting, and might be moveable towards the exit block. */
467 struct expr
* expr
; /* Gcse expression reference for LM. */
468 rtx pattern
; /* Pattern of this mem. */
469 rtx loads
; /* INSN list of loads seen. */
470 rtx stores
; /* INSN list of stores seen. */
471 struct ls_expr
* next
; /* Next in the list. */
472 int invalid
; /* Invalid for some reason. */
473 int index
; /* If it maps to a bitmap index. */
474 int hash_index
; /* Index when in a hash table. */
475 rtx reaching_reg
; /* Register to use when re-writing. */
478 /* Head of the list of load/store memory refs. */
479 static struct ls_expr
* pre_ldst_mems
= NULL
;
481 /* Bitmap containing one bit for each register in the program.
482 Used when performing GCSE to track which registers have been set since
483 the start of the basic block. */
484 static regset reg_set_bitmap
;
486 /* For each block, a bitmap of registers set in the block.
487 This is used by expr_killed_p and compute_transp.
488 It is computed during hash table computation and not by compute_sets
489 as it includes registers added since the last pass (or between cprop and
490 gcse) and it's currently not easy to realloc sbitmap vectors. */
491 static sbitmap
*reg_set_in_block
;
493 /* Array, indexed by basic block number for a list of insns which modify
494 memory within that block. */
495 static rtx
* modify_mem_list
;
496 bitmap modify_mem_list_set
;
498 /* This array parallels modify_mem_list, but is kept canonicalized. */
499 static rtx
* canon_modify_mem_list
;
500 bitmap canon_modify_mem_list_set
;
501 /* Various variables for statistics gathering. */
503 /* Memory used in a pass.
504 This isn't intended to be absolutely precise. Its intent is only
505 to keep an eye on memory usage. */
506 static int bytes_used
;
508 /* GCSE substitutions made. */
509 static int gcse_subst_count
;
510 /* Number of copy instructions created. */
511 static int gcse_create_count
;
512 /* Number of constants propagated. */
513 static int const_prop_count
;
514 /* Number of copys propagated. */
515 static int copy_prop_count
;
517 /* These variables are used by classic GCSE.
518 Normally they'd be defined a bit later, but `rd_gen' needs to
519 be declared sooner. */
521 /* Each block has a bitmap of each type.
522 The length of each blocks bitmap is:
524 max_cuid - for reaching definitions
525 n_exprs - for available expressions
527 Thus we view the bitmaps as 2 dimensional arrays. i.e.
528 rd_kill[block_num][cuid_num]
529 ae_kill[block_num][expr_num] */
531 /* For reaching defs */
532 static sbitmap
*rd_kill
, *rd_gen
, *reaching_defs
, *rd_out
;
534 /* for available exprs */
535 static sbitmap
*ae_kill
, *ae_gen
, *ae_in
, *ae_out
;
537 /* Objects of this type are passed around by the null-pointer check
539 struct null_pointer_info
541 /* The basic block being processed. */
542 basic_block current_block
;
543 /* The first register to be handled in this pass. */
544 unsigned int min_reg
;
545 /* One greater than the last register to be handled in this pass. */
546 unsigned int max_reg
;
547 sbitmap
*nonnull_local
;
548 sbitmap
*nonnull_killed
;
551 static void compute_can_copy
PARAMS ((void));
552 static char *gmalloc
PARAMS ((unsigned int));
553 static char *grealloc
PARAMS ((char *, unsigned int));
554 static char *gcse_alloc
PARAMS ((unsigned long));
555 static void alloc_gcse_mem
PARAMS ((rtx
));
556 static void free_gcse_mem
PARAMS ((void));
557 static void alloc_reg_set_mem
PARAMS ((int));
558 static void free_reg_set_mem
PARAMS ((void));
559 static int get_bitmap_width
PARAMS ((int, int, int));
560 static void record_one_set
PARAMS ((int, rtx
));
561 static void record_set_info
PARAMS ((rtx
, rtx
, void *));
562 static void compute_sets
PARAMS ((rtx
));
563 static void hash_scan_insn
PARAMS ((rtx
, int, int));
564 static void hash_scan_set
PARAMS ((rtx
, rtx
, int));
565 static void hash_scan_clobber
PARAMS ((rtx
, rtx
));
566 static void hash_scan_call
PARAMS ((rtx
, rtx
));
567 static int want_to_gcse_p
PARAMS ((rtx
));
568 static int oprs_unchanged_p
PARAMS ((rtx
, rtx
, int));
569 static int oprs_anticipatable_p
PARAMS ((rtx
, rtx
));
570 static int oprs_available_p
PARAMS ((rtx
, rtx
));
571 static void insert_expr_in_table
PARAMS ((rtx
, enum machine_mode
, rtx
,
573 static void insert_set_in_table
PARAMS ((rtx
, rtx
));
574 static unsigned int hash_expr
PARAMS ((rtx
, enum machine_mode
, int *, int));
575 static unsigned int hash_expr_1
PARAMS ((rtx
, enum machine_mode
, int *));
576 static unsigned int hash_string_1
PARAMS ((const char *));
577 static unsigned int hash_set
PARAMS ((int, int));
578 static int expr_equiv_p
PARAMS ((rtx
, rtx
));
579 static void record_last_reg_set_info
PARAMS ((rtx
, int));
580 static void record_last_mem_set_info
PARAMS ((rtx
));
581 static void record_last_set_info
PARAMS ((rtx
, rtx
, void *));
582 static void compute_hash_table
PARAMS ((int));
583 static void alloc_set_hash_table
PARAMS ((int));
584 static void free_set_hash_table
PARAMS ((void));
585 static void compute_set_hash_table
PARAMS ((void));
586 static void alloc_expr_hash_table
PARAMS ((unsigned int));
587 static void free_expr_hash_table
PARAMS ((void));
588 static void compute_expr_hash_table
PARAMS ((void));
589 static void dump_hash_table
PARAMS ((FILE *, const char *, struct expr
**,
591 static struct expr
*lookup_expr
PARAMS ((rtx
));
592 static struct expr
*lookup_set
PARAMS ((unsigned int, rtx
));
593 static struct expr
*next_set
PARAMS ((unsigned int, struct expr
*));
594 static void reset_opr_set_tables
PARAMS ((void));
595 static int oprs_not_set_p
PARAMS ((rtx
, rtx
));
596 static void mark_call
PARAMS ((rtx
));
597 static void mark_set
PARAMS ((rtx
, rtx
));
598 static void mark_clobber
PARAMS ((rtx
, rtx
));
599 static void mark_oprs_set
PARAMS ((rtx
));
600 static void alloc_cprop_mem
PARAMS ((int, int));
601 static void free_cprop_mem
PARAMS ((void));
602 static void compute_transp
PARAMS ((rtx
, int, sbitmap
*, int));
603 static void compute_transpout
PARAMS ((void));
604 static void compute_local_properties
PARAMS ((sbitmap
*, sbitmap
*, sbitmap
*,
606 static void compute_cprop_data
PARAMS ((void));
607 static void find_used_regs
PARAMS ((rtx
*, void *));
608 static int try_replace_reg
PARAMS ((rtx
, rtx
, rtx
));
609 static struct expr
*find_avail_set
PARAMS ((int, rtx
));
610 static int cprop_jump
PARAMS ((basic_block
, rtx
, rtx
, rtx
, rtx
));
611 static void mems_conflict_for_gcse_p
PARAMS ((rtx
, rtx
, void *));
612 static int load_killed_in_block_p
PARAMS ((basic_block
, int, rtx
, int));
613 static void canon_list_insert
PARAMS ((rtx
, rtx
, void *));
614 static int cprop_insn
PARAMS ((rtx
, int));
615 static int cprop
PARAMS ((int));
616 static int one_cprop_pass
PARAMS ((int, int));
617 static bool constprop_register
PARAMS ((rtx
, rtx
, rtx
, int));
618 static struct expr
*find_bypass_set
PARAMS ((int, int));
619 static int bypass_block
PARAMS ((basic_block
, rtx
, rtx
));
620 static int bypass_conditional_jumps
PARAMS ((void));
621 static void alloc_pre_mem
PARAMS ((int, int));
622 static void free_pre_mem
PARAMS ((void));
623 static void compute_pre_data
PARAMS ((void));
624 static int pre_expr_reaches_here_p
PARAMS ((basic_block
, struct expr
*,
626 static void insert_insn_end_bb
PARAMS ((struct expr
*, basic_block
, int));
627 static void pre_insert_copy_insn
PARAMS ((struct expr
*, rtx
));
628 static void pre_insert_copies
PARAMS ((void));
629 static int pre_delete
PARAMS ((void));
630 static int pre_gcse
PARAMS ((void));
631 static int one_pre_gcse_pass
PARAMS ((int));
632 static void add_label_notes
PARAMS ((rtx
, rtx
));
633 static void alloc_code_hoist_mem
PARAMS ((int, int));
634 static void free_code_hoist_mem
PARAMS ((void));
635 static void compute_code_hoist_vbeinout
PARAMS ((void));
636 static void compute_code_hoist_data
PARAMS ((void));
637 static int hoist_expr_reaches_here_p
PARAMS ((basic_block
, int, basic_block
,
639 static void hoist_code
PARAMS ((void));
640 static int one_code_hoisting_pass
PARAMS ((void));
641 static void alloc_rd_mem
PARAMS ((int, int));
642 static void free_rd_mem
PARAMS ((void));
643 static void handle_rd_kill_set
PARAMS ((rtx
, int, basic_block
));
644 static void compute_kill_rd
PARAMS ((void));
645 static void compute_rd
PARAMS ((void));
646 static void alloc_avail_expr_mem
PARAMS ((int, int));
647 static void free_avail_expr_mem
PARAMS ((void));
648 static void compute_ae_gen
PARAMS ((void));
649 static int expr_killed_p
PARAMS ((rtx
, basic_block
));
650 static void compute_ae_kill
PARAMS ((sbitmap
*, sbitmap
*));
651 static int expr_reaches_here_p
PARAMS ((struct occr
*, struct expr
*,
653 static rtx computing_insn
PARAMS ((struct expr
*, rtx
));
654 static int def_reaches_here_p
PARAMS ((rtx
, rtx
));
655 static int can_disregard_other_sets
PARAMS ((struct reg_set
**, rtx
, int));
656 static int handle_avail_expr
PARAMS ((rtx
, struct expr
*));
657 static int classic_gcse
PARAMS ((void));
658 static int one_classic_gcse_pass
PARAMS ((int));
659 static void invalidate_nonnull_info
PARAMS ((rtx
, rtx
, void *));
660 static int delete_null_pointer_checks_1
PARAMS ((unsigned int *,
661 sbitmap
*, sbitmap
*,
662 struct null_pointer_info
*));
663 static rtx process_insert_insn
PARAMS ((struct expr
*));
664 static int pre_edge_insert
PARAMS ((struct edge_list
*, struct expr
**));
665 static int expr_reaches_here_p_work
PARAMS ((struct occr
*, struct expr
*,
666 basic_block
, int, char *));
667 static int pre_expr_reaches_here_p_work
PARAMS ((basic_block
, struct expr
*,
668 basic_block
, char *));
669 static struct ls_expr
* ldst_entry
PARAMS ((rtx
));
670 static void free_ldst_entry
PARAMS ((struct ls_expr
*));
671 static void free_ldst_mems
PARAMS ((void));
672 static void print_ldst_list
PARAMS ((FILE *));
673 static struct ls_expr
* find_rtx_in_ldst
PARAMS ((rtx
));
674 static int enumerate_ldsts
PARAMS ((void));
675 static inline struct ls_expr
* first_ls_expr
PARAMS ((void));
676 static inline struct ls_expr
* next_ls_expr
PARAMS ((struct ls_expr
*));
677 static int simple_mem
PARAMS ((rtx
));
678 static void invalidate_any_buried_refs
PARAMS ((rtx
));
679 static void compute_ld_motion_mems
PARAMS ((void));
680 static void trim_ld_motion_mems
PARAMS ((void));
681 static void update_ld_motion_stores
PARAMS ((struct expr
*));
682 static void reg_set_info
PARAMS ((rtx
, rtx
, void *));
683 static int store_ops_ok
PARAMS ((rtx
, basic_block
));
684 static void find_moveable_store
PARAMS ((rtx
));
685 static int compute_store_table
PARAMS ((void));
686 static int load_kills_store
PARAMS ((rtx
, rtx
));
687 static int find_loads
PARAMS ((rtx
, rtx
));
688 static int store_killed_in_insn
PARAMS ((rtx
, rtx
));
689 static int store_killed_after
PARAMS ((rtx
, rtx
, basic_block
));
690 static int store_killed_before
PARAMS ((rtx
, rtx
, basic_block
));
691 static void build_store_vectors
PARAMS ((void));
692 static void insert_insn_start_bb
PARAMS ((rtx
, basic_block
));
693 static int insert_store
PARAMS ((struct ls_expr
*, edge
));
694 static void replace_store_insn
PARAMS ((rtx
, rtx
, basic_block
));
695 static void delete_store
PARAMS ((struct ls_expr
*,
697 static void free_store_memory
PARAMS ((void));
698 static void store_motion
PARAMS ((void));
699 static void free_insn_expr_list_list
PARAMS ((rtx
*));
700 static void clear_modify_mem_tables
PARAMS ((void));
701 static void free_modify_mem_tables
PARAMS ((void));
702 static rtx gcse_emit_move_after
PARAMS ((rtx
, rtx
, rtx
));
703 static bool do_local_cprop
PARAMS ((rtx
, rtx
, int));
704 static void local_cprop_pass
PARAMS ((int));
706 /* Entry point for global common subexpression elimination.
707 F is the first instruction in the function. */
715 /* Bytes used at start of pass. */
716 int initial_bytes_used
;
717 /* Maximum number of bytes used by a pass. */
719 /* Point to release obstack data from for each pass. */
720 char *gcse_obstack_bottom
;
722 /* Insertion of instructions on edges can create new basic blocks; we
723 need the original basic block count so that we can properly deallocate
724 arrays sized on the number of basic blocks originally in the cfg. */
726 /* We do not construct an accurate cfg in functions which call
727 setjmp, so just punt to be safe. */
728 if (current_function_calls_setjmp
)
731 /* Assume that we do not need to run jump optimizations after gcse. */
732 run_jump_opt_after_gcse
= 0;
734 /* For calling dump_foo fns from gdb. */
735 debug_stderr
= stderr
;
738 /* Identify the basic block information for this function, including
739 successors and predecessors. */
740 max_gcse_regno
= max_reg_num ();
743 dump_flow_info (file
);
745 orig_bb_count
= n_basic_blocks
;
746 /* Return if there's nothing to do. */
747 if (n_basic_blocks
<= 1)
750 /* Trying to perform global optimizations on flow graphs which have
751 a high connectivity will take a long time and is unlikely to be
754 In normal circumstances a cfg should have about twice as many edges
755 as blocks. But we do not want to punish small functions which have
756 a couple switch statements. So we require a relatively large number
757 of basic blocks and the ratio of edges to blocks to be high. */
758 if (n_basic_blocks
> 1000 && n_edges
/ n_basic_blocks
>= 20)
760 if (warn_disabled_optimization
)
761 warning ("GCSE disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
762 n_basic_blocks
, n_edges
/ n_basic_blocks
);
766 /* If allocating memory for the cprop bitmap would take up too much
767 storage it's better just to disable the optimization. */
769 * SBITMAP_SET_SIZE (max_gcse_regno
)
770 * sizeof (SBITMAP_ELT_TYPE
)) > MAX_GCSE_MEMORY
)
772 if (warn_disabled_optimization
)
773 warning ("GCSE disabled: %d basic blocks and %d registers",
774 n_basic_blocks
, max_gcse_regno
);
779 /* See what modes support reg/reg copy operations. */
780 if (! can_copy_init_p
)
786 gcc_obstack_init (&gcse_obstack
);
790 init_alias_analysis ();
791 /* Record where pseudo-registers are set. This data is kept accurate
792 during each pass. ??? We could also record hard-reg information here
793 [since it's unchanging], however it is currently done during hash table
796 It may be tempting to compute MEM set information here too, but MEM sets
797 will be subject to code motion one day and thus we need to compute
798 information about memory sets when we build the hash tables. */
800 alloc_reg_set_mem (max_gcse_regno
);
804 initial_bytes_used
= bytes_used
;
806 gcse_obstack_bottom
= gcse_alloc (1);
808 while (changed
&& pass
< MAX_GCSE_PASSES
)
812 fprintf (file
, "GCSE pass %d\n\n", pass
+ 1);
814 /* Initialize bytes_used to the space for the pred/succ lists,
815 and the reg_set_table data. */
816 bytes_used
= initial_bytes_used
;
818 /* Each pass may create new registers, so recalculate each time. */
819 max_gcse_regno
= max_reg_num ();
823 /* Don't allow constant propagation to modify jumps
825 changed
= one_cprop_pass (pass
+ 1, 0);
828 changed
|= one_classic_gcse_pass (pass
+ 1);
831 changed
|= one_pre_gcse_pass (pass
+ 1);
832 /* We may have just created new basic blocks. Release and
833 recompute various things which are sized on the number of
837 free_modify_mem_tables ();
839 = (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
840 canon_modify_mem_list
841 = (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
842 memset ((char *) modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
843 memset ((char *) canon_modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
844 orig_bb_count
= n_basic_blocks
;
847 alloc_reg_set_mem (max_reg_num ());
849 run_jump_opt_after_gcse
= 1;
852 if (max_pass_bytes
< bytes_used
)
853 max_pass_bytes
= bytes_used
;
855 /* Free up memory, then reallocate for code hoisting. We can
856 not re-use the existing allocated memory because the tables
857 will not have info for the insns or registers created by
858 partial redundancy elimination. */
861 /* It does not make sense to run code hoisting unless we optimizing
862 for code size -- it rarely makes programs faster, and can make
863 them bigger if we did partial redundancy elimination (when optimizing
864 for space, we use a classic gcse algorithm instead of partial
865 redundancy algorithms). */
868 max_gcse_regno
= max_reg_num ();
870 changed
|= one_code_hoisting_pass ();
873 if (max_pass_bytes
< bytes_used
)
874 max_pass_bytes
= bytes_used
;
879 fprintf (file
, "\n");
883 obstack_free (&gcse_obstack
, gcse_obstack_bottom
);
887 /* Do one last pass of copy propagation, including cprop into
888 conditional jumps. */
890 max_gcse_regno
= max_reg_num ();
892 /* This time, go ahead and allow cprop to alter jumps. */
893 one_cprop_pass (pass
+ 1, 1);
898 fprintf (file
, "GCSE of %s: %d basic blocks, ",
899 current_function_name
, n_basic_blocks
);
900 fprintf (file
, "%d pass%s, %d bytes\n\n",
901 pass
, pass
> 1 ? "es" : "", max_pass_bytes
);
904 obstack_free (&gcse_obstack
, NULL
);
906 /* We are finished with alias. */
907 end_alias_analysis ();
908 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
910 /* Store motion disabled until it is fixed. */
911 if (0 && !optimize_size
&& flag_gcse_sm
)
913 /* Record where pseudo-registers are set. */
914 return run_jump_opt_after_gcse
;
917 /* Misc. utilities. */
919 /* Compute which modes support reg/reg copy operations. */
925 #ifndef AVOID_CCMODE_COPIES
928 memset (can_copy_p
, 0, NUM_MACHINE_MODES
);
931 for (i
= 0; i
< NUM_MACHINE_MODES
; i
++)
932 if (GET_MODE_CLASS (i
) == MODE_CC
)
934 #ifdef AVOID_CCMODE_COPIES
937 reg
= gen_rtx_REG ((enum machine_mode
) i
, LAST_VIRTUAL_REGISTER
+ 1);
938 insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, reg
));
939 if (recog (PATTERN (insn
), insn
, NULL
) >= 0)
949 /* Cover function to xmalloc to record bytes allocated. */
956 return xmalloc (size
);
959 /* Cover function to xrealloc.
960 We don't record the additional size since we don't know it.
961 It won't affect memory usage stats much anyway. */
968 return xrealloc (ptr
, size
);
971 /* Cover function to obstack_alloc. */
978 return (char *) obstack_alloc (&gcse_obstack
, size
);
981 /* Allocate memory for the cuid mapping array,
982 and reg/memory set tracking tables.
984 This is called at the start of each pass. */
993 /* Find the largest UID and create a mapping from UIDs to CUIDs.
994 CUIDs are like UIDs except they increase monotonically, have no gaps,
995 and only apply to real insns. */
997 max_uid
= get_max_uid ();
998 n
= (max_uid
+ 1) * sizeof (int);
999 uid_cuid
= (int *) gmalloc (n
);
1000 memset ((char *) uid_cuid
, 0, n
);
1001 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
1004 uid_cuid
[INSN_UID (insn
)] = i
++;
1006 uid_cuid
[INSN_UID (insn
)] = i
;
1009 /* Create a table mapping cuids to insns. */
1012 n
= (max_cuid
+ 1) * sizeof (rtx
);
1013 cuid_insn
= (rtx
*) gmalloc (n
);
1014 memset ((char *) cuid_insn
, 0, n
);
1015 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
1017 CUID_INSN (i
++) = insn
;
1019 /* Allocate vars to track sets of regs. */
1020 reg_set_bitmap
= BITMAP_XMALLOC ();
1022 /* Allocate vars to track sets of regs, memory per block. */
1023 reg_set_in_block
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
,
1025 /* Allocate array to keep a list of insns which modify memory in each
1027 modify_mem_list
= (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
1028 canon_modify_mem_list
= (rtx
*) gmalloc (last_basic_block
* sizeof (rtx
));
1029 memset ((char *) modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
1030 memset ((char *) canon_modify_mem_list
, 0, last_basic_block
* sizeof (rtx
));
1031 modify_mem_list_set
= BITMAP_XMALLOC ();
1032 canon_modify_mem_list_set
= BITMAP_XMALLOC ();
1035 /* Free memory allocated by alloc_gcse_mem. */
1043 BITMAP_XFREE (reg_set_bitmap
);
1045 sbitmap_vector_free (reg_set_in_block
);
1046 free_modify_mem_tables ();
1047 BITMAP_XFREE (modify_mem_list_set
);
1048 BITMAP_XFREE (canon_modify_mem_list_set
);
1051 /* Many of the global optimization algorithms work by solving dataflow
1052 equations for various expressions. Initially, some local value is
1053 computed for each expression in each block. Then, the values across the
1054 various blocks are combined (by following flow graph edges) to arrive at
1055 global values. Conceptually, each set of equations is independent. We
1056 may therefore solve all the equations in parallel, solve them one at a
1057 time, or pick any intermediate approach.
1059 When you're going to need N two-dimensional bitmaps, each X (say, the
1060 number of blocks) by Y (say, the number of expressions), call this
1061 function. It's not important what X and Y represent; only that Y
1062 correspond to the things that can be done in parallel. This function will
1063 return an appropriate chunking factor C; you should solve C sets of
1064 equations in parallel. By going through this function, we can easily
1065 trade space against time; by solving fewer equations in parallel we use
1069 get_bitmap_width (n
, x
, y
)
1074 /* It's not really worth figuring out *exactly* how much memory will
1075 be used by a particular choice. The important thing is to get
1076 something approximately right. */
1077 size_t max_bitmap_memory
= 10 * 1024 * 1024;
1079 /* The number of bytes we'd use for a single column of minimum
1081 size_t column_size
= n
* x
* sizeof (SBITMAP_ELT_TYPE
);
1083 /* Often, it's reasonable just to solve all the equations in
1085 if (column_size
* SBITMAP_SET_SIZE (y
) <= max_bitmap_memory
)
1088 /* Otherwise, pick the largest width we can, without going over the
1090 return SBITMAP_ELT_BITS
* ((max_bitmap_memory
+ column_size
- 1)
1094 /* Compute the local properties of each recorded expression.
1096 Local properties are those that are defined by the block, irrespective of
1099 An expression is transparent in a block if its operands are not modified
1102 An expression is computed (locally available) in a block if it is computed
1103 at least once and expression would contain the same value if the
1104 computation was moved to the end of the block.
1106 An expression is locally anticipatable in a block if it is computed at
1107 least once and expression would contain the same value if the computation
1108 was moved to the beginning of the block.
1110 We call this routine for cprop, pre and code hoisting. They all compute
1111 basically the same information and thus can easily share this code.
1113 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1114 properties. If NULL, then it is not necessary to compute or record that
1115 particular property.
1117 SETP controls which hash table to look at. If zero, this routine looks at
1118 the expr hash table; if nonzero this routine looks at the set hash table.
1119 Additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1123 compute_local_properties (transp
, comp
, antloc
, setp
)
1129 unsigned int i
, hash_table_size
;
1130 struct expr
**hash_table
;
1132 /* Initialize any bitmaps that were passed in. */
1136 sbitmap_vector_zero (transp
, last_basic_block
);
1138 sbitmap_vector_ones (transp
, last_basic_block
);
1142 sbitmap_vector_zero (comp
, last_basic_block
);
1144 sbitmap_vector_zero (antloc
, last_basic_block
);
1146 /* We use the same code for cprop, pre and hoisting. For cprop
1147 we care about the set hash table, for pre and hoisting we
1148 care about the expr hash table. */
1149 hash_table_size
= setp
? set_hash_table_size
: expr_hash_table_size
;
1150 hash_table
= setp
? set_hash_table
: expr_hash_table
;
1152 for (i
= 0; i
< hash_table_size
; i
++)
1156 for (expr
= hash_table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1158 int indx
= expr
->bitmap_index
;
1161 /* The expression is transparent in this block if it is not killed.
1162 We start by assuming all are transparent [none are killed], and
1163 then reset the bits for those that are. */
1165 compute_transp (expr
->expr
, indx
, transp
, setp
);
1167 /* The occurrences recorded in antic_occr are exactly those that
1168 we want to set to non-zero in ANTLOC. */
1170 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
1172 SET_BIT (antloc
[BLOCK_NUM (occr
->insn
)], indx
);
1174 /* While we're scanning the table, this is a good place to
1176 occr
->deleted_p
= 0;
1179 /* The occurrences recorded in avail_occr are exactly those that
1180 we want to set to non-zero in COMP. */
1182 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
1184 SET_BIT (comp
[BLOCK_NUM (occr
->insn
)], indx
);
1186 /* While we're scanning the table, this is a good place to
1191 /* While we're scanning the table, this is a good place to
1193 expr
->reaching_reg
= 0;
1198 /* Register set information.
1200 `reg_set_table' records where each register is set or otherwise
1203 static struct obstack reg_set_obstack
;
1206 alloc_reg_set_mem (n_regs
)
1211 reg_set_table_size
= n_regs
+ REG_SET_TABLE_SLOP
;
1212 n
= reg_set_table_size
* sizeof (struct reg_set
*);
1213 reg_set_table
= (struct reg_set
**) gmalloc (n
);
1214 memset ((char *) reg_set_table
, 0, n
);
1216 gcc_obstack_init (®_set_obstack
);
1222 free (reg_set_table
);
1223 obstack_free (®_set_obstack
, NULL
);
1226 /* Record REGNO in the reg_set table. */
1229 record_one_set (regno
, insn
)
1233 /* Allocate a new reg_set element and link it onto the list. */
1234 struct reg_set
*new_reg_info
;
1236 /* If the table isn't big enough, enlarge it. */
1237 if (regno
>= reg_set_table_size
)
1239 int new_size
= regno
+ REG_SET_TABLE_SLOP
;
1242 = (struct reg_set
**) grealloc ((char *) reg_set_table
,
1243 new_size
* sizeof (struct reg_set
*));
1244 memset ((char *) (reg_set_table
+ reg_set_table_size
), 0,
1245 (new_size
- reg_set_table_size
) * sizeof (struct reg_set
*));
1246 reg_set_table_size
= new_size
;
1249 new_reg_info
= (struct reg_set
*) obstack_alloc (®_set_obstack
,
1250 sizeof (struct reg_set
));
1251 bytes_used
+= sizeof (struct reg_set
);
1252 new_reg_info
->insn
= insn
;
1253 new_reg_info
->next
= reg_set_table
[regno
];
1254 reg_set_table
[regno
] = new_reg_info
;
1257 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1258 an insn. The DATA is really the instruction in which the SET is
1262 record_set_info (dest
, setter
, data
)
1263 rtx dest
, setter ATTRIBUTE_UNUSED
;
1266 rtx record_set_insn
= (rtx
) data
;
1268 if (GET_CODE (dest
) == REG
&& REGNO (dest
) >= FIRST_PSEUDO_REGISTER
)
1269 record_one_set (REGNO (dest
), record_set_insn
);
1272 /* Scan the function and record each set of each pseudo-register.
1274 This is called once, at the start of the gcse pass. See the comments for
1275 `reg_set_table' for further documenation. */
1283 for (insn
= f
; insn
!= 0; insn
= NEXT_INSN (insn
))
1285 note_stores (PATTERN (insn
), record_set_info
, insn
);
1288 /* Hash table support. */
1290 struct reg_avail_info
1292 basic_block last_bb
;
1297 static struct reg_avail_info
*reg_avail_info
;
1298 static basic_block current_bb
;
1301 /* See whether X, the source of a set, is something we want to consider for
1304 static GTY(()) rtx test_insn
;
1309 int num_clobbers
= 0;
1312 switch (GET_CODE (x
))
1326 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1327 if (general_operand (x
, GET_MODE (x
)))
1329 else if (GET_MODE (x
) == VOIDmode
)
1332 /* Otherwise, check if we can make a valid insn from it. First initialize
1333 our test insn if we haven't already. */
1337 = make_insn_raw (gen_rtx_SET (VOIDmode
,
1338 gen_rtx_REG (word_mode
,
1339 FIRST_PSEUDO_REGISTER
* 2),
1341 NEXT_INSN (test_insn
) = PREV_INSN (test_insn
) = 0;
1344 /* Now make an insn like the one we would make when GCSE'ing and see if
1346 PUT_MODE (SET_DEST (PATTERN (test_insn
)), GET_MODE (x
));
1347 SET_SRC (PATTERN (test_insn
)) = x
;
1348 return ((icode
= recog (PATTERN (test_insn
), test_insn
, &num_clobbers
)) >= 0
1349 && (num_clobbers
== 0 || ! added_clobbers_hard_reg_p (icode
)));
1352 /* Return non-zero if the operands of expression X are unchanged from the
1353 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1354 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1357 oprs_unchanged_p (x
, insn
, avail_p
)
1368 code
= GET_CODE (x
);
1373 struct reg_avail_info
*info
= ®_avail_info
[REGNO (x
)];
1375 if (info
->last_bb
!= current_bb
)
1378 return info
->last_set
< INSN_CUID (insn
);
1380 return info
->first_set
>= INSN_CUID (insn
);
1384 if (load_killed_in_block_p (current_bb
, INSN_CUID (insn
),
1388 return oprs_unchanged_p (XEXP (x
, 0), insn
, avail_p
);
1414 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1418 /* If we are about to do the last recursive call needed at this
1419 level, change it into iteration. This function is called enough
1422 return oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
);
1424 else if (! oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
))
1427 else if (fmt
[i
] == 'E')
1428 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1429 if (! oprs_unchanged_p (XVECEXP (x
, i
, j
), insn
, avail_p
))
1436 /* Used for communication between mems_conflict_for_gcse_p and
1437 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1438 conflict between two memory references. */
1439 static int gcse_mems_conflict_p
;
1441 /* Used for communication between mems_conflict_for_gcse_p and
1442 load_killed_in_block_p. A memory reference for a load instruction,
1443 mems_conflict_for_gcse_p will see if a memory store conflicts with
1444 this memory load. */
1445 static rtx gcse_mem_operand
;
1447 /* DEST is the output of an instruction. If it is a memory reference, and
1448 possibly conflicts with the load found in gcse_mem_operand, then set
1449 gcse_mems_conflict_p to a nonzero value. */
1452 mems_conflict_for_gcse_p (dest
, setter
, data
)
1453 rtx dest
, setter ATTRIBUTE_UNUSED
;
1454 void *data ATTRIBUTE_UNUSED
;
1456 while (GET_CODE (dest
) == SUBREG
1457 || GET_CODE (dest
) == ZERO_EXTRACT
1458 || GET_CODE (dest
) == SIGN_EXTRACT
1459 || GET_CODE (dest
) == STRICT_LOW_PART
)
1460 dest
= XEXP (dest
, 0);
1462 /* If DEST is not a MEM, then it will not conflict with the load. Note
1463 that function calls are assumed to clobber memory, but are handled
1465 if (GET_CODE (dest
) != MEM
)
1468 /* If we are setting a MEM in our list of specially recognized MEMs,
1469 don't mark as killed this time. */
1471 if (dest
== gcse_mem_operand
&& pre_ldst_mems
!= NULL
)
1473 if (!find_rtx_in_ldst (dest
))
1474 gcse_mems_conflict_p
= 1;
1478 if (true_dependence (dest
, GET_MODE (dest
), gcse_mem_operand
,
1480 gcse_mems_conflict_p
= 1;
1483 /* Return nonzero if the expression in X (a memory reference) is killed
1484 in block BB before or after the insn with the CUID in UID_LIMIT.
1485 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1488 To check the entire block, set UID_LIMIT to max_uid + 1 and
1492 load_killed_in_block_p (bb
, uid_limit
, x
, avail_p
)
1498 rtx list_entry
= modify_mem_list
[bb
->index
];
1502 /* Ignore entries in the list that do not apply. */
1504 && INSN_CUID (XEXP (list_entry
, 0)) < uid_limit
)
1506 && INSN_CUID (XEXP (list_entry
, 0)) > uid_limit
))
1508 list_entry
= XEXP (list_entry
, 1);
1512 setter
= XEXP (list_entry
, 0);
1514 /* If SETTER is a call everything is clobbered. Note that calls
1515 to pure functions are never put on the list, so we need not
1516 worry about them. */
1517 if (GET_CODE (setter
) == CALL_INSN
)
1520 /* SETTER must be an INSN of some kind that sets memory. Call
1521 note_stores to examine each hunk of memory that is modified.
1523 The note_stores interface is pretty limited, so we have to
1524 communicate via global variables. Yuk. */
1525 gcse_mem_operand
= x
;
1526 gcse_mems_conflict_p
= 0;
1527 note_stores (PATTERN (setter
), mems_conflict_for_gcse_p
, NULL
);
1528 if (gcse_mems_conflict_p
)
1530 list_entry
= XEXP (list_entry
, 1);
1535 /* Return non-zero if the operands of expression X are unchanged from
1536 the start of INSN's basic block up to but not including INSN. */
1539 oprs_anticipatable_p (x
, insn
)
1542 return oprs_unchanged_p (x
, insn
, 0);
1545 /* Return non-zero if the operands of expression X are unchanged from
1546 INSN to the end of INSN's basic block. */
1549 oprs_available_p (x
, insn
)
1552 return oprs_unchanged_p (x
, insn
, 1);
1555 /* Hash expression X.
1557 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1558 indicating if a volatile operand is found or if the expression contains
1559 something we don't want to insert in the table.
1561 ??? One might want to merge this with canon_hash. Later. */
1564 hash_expr (x
, mode
, do_not_record_p
, hash_table_size
)
1566 enum machine_mode mode
;
1567 int *do_not_record_p
;
1568 int hash_table_size
;
1572 *do_not_record_p
= 0;
1574 hash
= hash_expr_1 (x
, mode
, do_not_record_p
);
1575 return hash
% hash_table_size
;
1578 /* Hash a string. Just add its bytes up. */
1580 static inline unsigned
1585 const unsigned char *p
= (const unsigned char *) ps
;
1594 /* Subroutine of hash_expr to do the actual work. */
1597 hash_expr_1 (x
, mode
, do_not_record_p
)
1599 enum machine_mode mode
;
1600 int *do_not_record_p
;
1607 /* Used to turn recursion into iteration. We can't rely on GCC's
1608 tail-recursion eliminatio since we need to keep accumulating values
1615 code
= GET_CODE (x
);
1619 hash
+= ((unsigned int) REG
<< 7) + REGNO (x
);
1623 hash
+= (((unsigned int) CONST_INT
<< 7) + (unsigned int) mode
1624 + (unsigned int) INTVAL (x
));
1628 /* This is like the general case, except that it only counts
1629 the integers representing the constant. */
1630 hash
+= (unsigned int) code
+ (unsigned int) GET_MODE (x
);
1631 if (GET_MODE (x
) != VOIDmode
)
1632 for (i
= 2; i
< GET_RTX_LENGTH (CONST_DOUBLE
); i
++)
1633 hash
+= (unsigned int) XWINT (x
, i
);
1635 hash
+= ((unsigned int) CONST_DOUBLE_LOW (x
)
1636 + (unsigned int) CONST_DOUBLE_HIGH (x
));
1644 units
= CONST_VECTOR_NUNITS (x
);
1646 for (i
= 0; i
< units
; ++i
)
1648 elt
= CONST_VECTOR_ELT (x
, i
);
1649 hash
+= hash_expr_1 (elt
, GET_MODE (elt
), do_not_record_p
);
1655 /* Assume there is only one rtx object for any given label. */
1657 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1658 differences and differences between each stage's debugging dumps. */
1659 hash
+= (((unsigned int) LABEL_REF
<< 7)
1660 + CODE_LABEL_NUMBER (XEXP (x
, 0)));
1665 /* Don't hash on the symbol's address to avoid bootstrap differences.
1666 Different hash values may cause expressions to be recorded in
1667 different orders and thus different registers to be used in the
1668 final assembler. This also avoids differences in the dump files
1669 between various stages. */
1671 const unsigned char *p
= (const unsigned char *) XSTR (x
, 0);
1674 h
+= (h
<< 7) + *p
++; /* ??? revisit */
1676 hash
+= ((unsigned int) SYMBOL_REF
<< 7) + h
;
1681 if (MEM_VOLATILE_P (x
))
1683 *do_not_record_p
= 1;
1687 hash
+= (unsigned int) MEM
;
1688 /* We used alias set for hashing, but this is not good, since the alias
1689 set may differ in -fprofile-arcs and -fbranch-probabilities compilation
1690 causing the profiles to fail to match. */
1701 case UNSPEC_VOLATILE
:
1702 *do_not_record_p
= 1;
1706 if (MEM_VOLATILE_P (x
))
1708 *do_not_record_p
= 1;
1713 /* We don't want to take the filename and line into account. */
1714 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
)
1715 + hash_string_1 (ASM_OPERANDS_TEMPLATE (x
))
1716 + hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
))
1717 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x
);
1719 if (ASM_OPERANDS_INPUT_LENGTH (x
))
1721 for (i
= 1; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
1723 hash
+= (hash_expr_1 (ASM_OPERANDS_INPUT (x
, i
),
1724 GET_MODE (ASM_OPERANDS_INPUT (x
, i
)),
1726 + hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT
1730 hash
+= hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x
, 0));
1731 x
= ASM_OPERANDS_INPUT (x
, 0);
1732 mode
= GET_MODE (x
);
1742 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
);
1743 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1747 /* If we are about to do the last recursive call
1748 needed at this level, change it into iteration.
1749 This function is called enough to be worth it. */
1756 hash
+= hash_expr_1 (XEXP (x
, i
), 0, do_not_record_p
);
1757 if (*do_not_record_p
)
1761 else if (fmt
[i
] == 'E')
1762 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1764 hash
+= hash_expr_1 (XVECEXP (x
, i
, j
), 0, do_not_record_p
);
1765 if (*do_not_record_p
)
1769 else if (fmt
[i
] == 's')
1770 hash
+= hash_string_1 (XSTR (x
, i
));
1771 else if (fmt
[i
] == 'i')
1772 hash
+= (unsigned int) XINT (x
, i
);
1780 /* Hash a set of register REGNO.
1782 Sets are hashed on the register that is set. This simplifies the PRE copy
1785 ??? May need to make things more elaborate. Later, as necessary. */
1788 hash_set (regno
, hash_table_size
)
1790 int hash_table_size
;
1795 return hash
% hash_table_size
;
1798 /* Return non-zero if exp1 is equivalent to exp2.
1799 ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
1812 if (x
== 0 || y
== 0)
1815 code
= GET_CODE (x
);
1816 if (code
!= GET_CODE (y
))
1819 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
1820 if (GET_MODE (x
) != GET_MODE (y
))
1830 return INTVAL (x
) == INTVAL (y
);
1833 return XEXP (x
, 0) == XEXP (y
, 0);
1836 return XSTR (x
, 0) == XSTR (y
, 0);
1839 return REGNO (x
) == REGNO (y
);
1842 /* Can't merge two expressions in different alias sets, since we can
1843 decide that the expression is transparent in a block when it isn't,
1844 due to it being set with the different alias set. */
1845 if (MEM_ALIAS_SET (x
) != MEM_ALIAS_SET (y
))
1849 /* For commutative operations, check both orders. */
1857 return ((expr_equiv_p (XEXP (x
, 0), XEXP (y
, 0))
1858 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 1)))
1859 || (expr_equiv_p (XEXP (x
, 0), XEXP (y
, 1))
1860 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 0))));
1863 /* We don't use the generic code below because we want to
1864 disregard filename and line numbers. */
1866 /* A volatile asm isn't equivalent to any other. */
1867 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
1870 if (GET_MODE (x
) != GET_MODE (y
)
1871 || strcmp (ASM_OPERANDS_TEMPLATE (x
), ASM_OPERANDS_TEMPLATE (y
))
1872 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
),
1873 ASM_OPERANDS_OUTPUT_CONSTRAINT (y
))
1874 || ASM_OPERANDS_OUTPUT_IDX (x
) != ASM_OPERANDS_OUTPUT_IDX (y
)
1875 || ASM_OPERANDS_INPUT_LENGTH (x
) != ASM_OPERANDS_INPUT_LENGTH (y
))
1878 if (ASM_OPERANDS_INPUT_LENGTH (x
))
1880 for (i
= ASM_OPERANDS_INPUT_LENGTH (x
) - 1; i
>= 0; i
--)
1881 if (! expr_equiv_p (ASM_OPERANDS_INPUT (x
, i
),
1882 ASM_OPERANDS_INPUT (y
, i
))
1883 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x
, i
),
1884 ASM_OPERANDS_INPUT_CONSTRAINT (y
, i
)))
1894 /* Compare the elements. If any pair of corresponding elements
1895 fail to match, return 0 for the whole thing. */
1897 fmt
= GET_RTX_FORMAT (code
);
1898 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1903 if (! expr_equiv_p (XEXP (x
, i
), XEXP (y
, i
)))
1908 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1910 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1911 if (! expr_equiv_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
1916 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1921 if (XINT (x
, i
) != XINT (y
, i
))
1926 if (XWINT (x
, i
) != XWINT (y
, i
))
1941 /* Insert expression X in INSN in the hash table.
1942 If it is already present, record it as the last occurrence in INSN's
1945 MODE is the mode of the value X is being stored into.
1946 It is only used if X is a CONST_INT.
1948 ANTIC_P is non-zero if X is an anticipatable expression.
1949 AVAIL_P is non-zero if X is an available expression. */
1952 insert_expr_in_table (x
, mode
, insn
, antic_p
, avail_p
)
1954 enum machine_mode mode
;
1956 int antic_p
, avail_p
;
1958 int found
, do_not_record_p
;
1960 struct expr
*cur_expr
, *last_expr
= NULL
;
1961 struct occr
*antic_occr
, *avail_occr
;
1962 struct occr
*last_occr
= NULL
;
1964 hash
= hash_expr (x
, mode
, &do_not_record_p
, expr_hash_table_size
);
1966 /* Do not insert expression in table if it contains volatile operands,
1967 or if hash_expr determines the expression is something we don't want
1968 to or can't handle. */
1969 if (do_not_record_p
)
1972 cur_expr
= expr_hash_table
[hash
];
1975 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1977 /* If the expression isn't found, save a pointer to the end of
1979 last_expr
= cur_expr
;
1980 cur_expr
= cur_expr
->next_same_hash
;
1985 cur_expr
= (struct expr
*) gcse_alloc (sizeof (struct expr
));
1986 bytes_used
+= sizeof (struct expr
);
1987 if (expr_hash_table
[hash
] == NULL
)
1988 /* This is the first pattern that hashed to this index. */
1989 expr_hash_table
[hash
] = cur_expr
;
1991 /* Add EXPR to end of this hash chain. */
1992 last_expr
->next_same_hash
= cur_expr
;
1994 /* Set the fields of the expr element. */
1996 cur_expr
->bitmap_index
= n_exprs
++;
1997 cur_expr
->next_same_hash
= NULL
;
1998 cur_expr
->antic_occr
= NULL
;
1999 cur_expr
->avail_occr
= NULL
;
2002 /* Now record the occurrence(s). */
2005 antic_occr
= cur_expr
->antic_occr
;
2007 /* Search for another occurrence in the same basic block. */
2008 while (antic_occr
&& BLOCK_NUM (antic_occr
->insn
) != BLOCK_NUM (insn
))
2010 /* If an occurrence isn't found, save a pointer to the end of
2012 last_occr
= antic_occr
;
2013 antic_occr
= antic_occr
->next
;
2017 /* Found another instance of the expression in the same basic block.
2018 Prefer the currently recorded one. We want the first one in the
2019 block and the block is scanned from start to end. */
2020 ; /* nothing to do */
2023 /* First occurrence of this expression in this basic block. */
2024 antic_occr
= (struct occr
*) gcse_alloc (sizeof (struct occr
));
2025 bytes_used
+= sizeof (struct occr
);
2026 /* First occurrence of this expression in any block? */
2027 if (cur_expr
->antic_occr
== NULL
)
2028 cur_expr
->antic_occr
= antic_occr
;
2030 last_occr
->next
= antic_occr
;
2032 antic_occr
->insn
= insn
;
2033 antic_occr
->next
= NULL
;
2039 avail_occr
= cur_expr
->avail_occr
;
2041 /* Search for another occurrence in the same basic block. */
2042 while (avail_occr
&& BLOCK_NUM (avail_occr
->insn
) != BLOCK_NUM (insn
))
2044 /* If an occurrence isn't found, save a pointer to the end of
2046 last_occr
= avail_occr
;
2047 avail_occr
= avail_occr
->next
;
2051 /* Found another instance of the expression in the same basic block.
2052 Prefer this occurrence to the currently recorded one. We want
2053 the last one in the block and the block is scanned from start
2055 avail_occr
->insn
= insn
;
2058 /* First occurrence of this expression in this basic block. */
2059 avail_occr
= (struct occr
*) gcse_alloc (sizeof (struct occr
));
2060 bytes_used
+= sizeof (struct occr
);
2062 /* First occurrence of this expression in any block? */
2063 if (cur_expr
->avail_occr
== NULL
)
2064 cur_expr
->avail_occr
= avail_occr
;
2066 last_occr
->next
= avail_occr
;
2068 avail_occr
->insn
= insn
;
2069 avail_occr
->next
= NULL
;
2074 /* Insert pattern X in INSN in the hash table.
2075 X is a SET of a reg to either another reg or a constant.
2076 If it is already present, record it as the last occurrence in INSN's
2080 insert_set_in_table (x
, insn
)
2086 struct expr
*cur_expr
, *last_expr
= NULL
;
2087 struct occr
*cur_occr
, *last_occr
= NULL
;
2089 if (GET_CODE (x
) != SET
2090 || GET_CODE (SET_DEST (x
)) != REG
)
2093 hash
= hash_set (REGNO (SET_DEST (x
)), set_hash_table_size
);
2095 cur_expr
= set_hash_table
[hash
];
2098 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
2100 /* If the expression isn't found, save a pointer to the end of
2102 last_expr
= cur_expr
;
2103 cur_expr
= cur_expr
->next_same_hash
;
2108 cur_expr
= (struct expr
*) gcse_alloc (sizeof (struct expr
));
2109 bytes_used
+= sizeof (struct expr
);
2110 if (set_hash_table
[hash
] == NULL
)
2111 /* This is the first pattern that hashed to this index. */
2112 set_hash_table
[hash
] = cur_expr
;
2114 /* Add EXPR to end of this hash chain. */
2115 last_expr
->next_same_hash
= cur_expr
;
2117 /* Set the fields of the expr element.
2118 We must copy X because it can be modified when copy propagation is
2119 performed on its operands. */
2120 cur_expr
->expr
= copy_rtx (x
);
2121 cur_expr
->bitmap_index
= n_sets
++;
2122 cur_expr
->next_same_hash
= NULL
;
2123 cur_expr
->antic_occr
= NULL
;
2124 cur_expr
->avail_occr
= NULL
;
2127 /* Now record the occurrence. */
2128 cur_occr
= cur_expr
->avail_occr
;
2130 /* Search for another occurrence in the same basic block. */
2131 while (cur_occr
&& BLOCK_NUM (cur_occr
->insn
) != BLOCK_NUM (insn
))
2133 /* If an occurrence isn't found, save a pointer to the end of
2135 last_occr
= cur_occr
;
2136 cur_occr
= cur_occr
->next
;
2140 /* Found another instance of the expression in the same basic block.
2141 Prefer this occurrence to the currently recorded one. We want the
2142 last one in the block and the block is scanned from start to end. */
2143 cur_occr
->insn
= insn
;
2146 /* First occurrence of this expression in this basic block. */
2147 cur_occr
= (struct occr
*) gcse_alloc (sizeof (struct occr
));
2148 bytes_used
+= sizeof (struct occr
);
2150 /* First occurrence of this expression in any block? */
2151 if (cur_expr
->avail_occr
== NULL
)
2152 cur_expr
->avail_occr
= cur_occr
;
2154 last_occr
->next
= cur_occr
;
2156 cur_occr
->insn
= insn
;
2157 cur_occr
->next
= NULL
;
2161 /* Scan pattern PAT of INSN and add an entry to the hash table. If SET_P is
2162 non-zero, this is for the assignment hash table, otherwise it is for the
2163 expression hash table. */
2166 hash_scan_set (pat
, insn
, set_p
)
2170 rtx src
= SET_SRC (pat
);
2171 rtx dest
= SET_DEST (pat
);
2174 if (GET_CODE (src
) == CALL
)
2175 hash_scan_call (src
, insn
);
2177 else if (GET_CODE (dest
) == REG
)
2179 unsigned int regno
= REGNO (dest
);
2182 /* If this is a single set and we are doing constant propagation,
2183 see if a REG_NOTE shows this equivalent to a constant. */
2184 if (set_p
&& (note
= find_reg_equal_equiv_note (insn
)) != 0
2185 && CONSTANT_P (XEXP (note
, 0)))
2186 src
= XEXP (note
, 0), pat
= gen_rtx_SET (VOIDmode
, dest
, src
);
2188 /* Only record sets of pseudo-regs in the hash table. */
2190 && regno
>= FIRST_PSEUDO_REGISTER
2191 /* Don't GCSE something if we can't do a reg/reg copy. */
2192 && can_copy_p
[GET_MODE (dest
)]
2193 /* GCSE commonly inserts instruction after the insn. We can't
2194 do that easily for EH_REGION notes so disable GCSE on these
2196 && !find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
2197 /* Is SET_SRC something we want to gcse? */
2198 && want_to_gcse_p (src
)
2199 /* Don't CSE a nop. */
2200 && ! set_noop_p (pat
)
2201 /* Don't GCSE if it has attached REG_EQUIV note.
2202 At this point this only function parameters should have
2203 REG_EQUIV notes and if the argument slot is used somewhere
2204 explicitly, it means address of parameter has been taken,
2205 so we should not extend the lifetime of the pseudo. */
2206 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
2207 || GET_CODE (XEXP (note
, 0)) != MEM
))
2209 /* An expression is not anticipatable if its operands are
2210 modified before this insn or if this is not the only SET in
2212 int antic_p
= oprs_anticipatable_p (src
, insn
) && single_set (insn
);
2213 /* An expression is not available if its operands are
2214 subsequently modified, including this insn. It's also not
2215 available if this is a branch, because we can't insert
2216 a set after the branch. */
2217 int avail_p
= (oprs_available_p (src
, insn
)
2218 && ! JUMP_P (insn
));
2220 insert_expr_in_table (src
, GET_MODE (dest
), insn
, antic_p
, avail_p
);
2223 /* Record sets for constant/copy propagation. */
2225 && regno
>= FIRST_PSEUDO_REGISTER
2226 && ((GET_CODE (src
) == REG
2227 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
2228 && can_copy_p
[GET_MODE (dest
)]
2229 && REGNO (src
) != regno
)
2230 || CONSTANT_P (src
))
2231 /* A copy is not available if its src or dest is subsequently
2232 modified. Here we want to search from INSN+1 on, but
2233 oprs_available_p searches from INSN on. */
2234 && (insn
== BLOCK_END (BLOCK_NUM (insn
))
2235 || ((tmp
= next_nonnote_insn (insn
)) != NULL_RTX
2236 && oprs_available_p (pat
, tmp
))))
2237 insert_set_in_table (pat
, insn
);
2242 hash_scan_clobber (x
, insn
)
2243 rtx x ATTRIBUTE_UNUSED
, insn ATTRIBUTE_UNUSED
;
2245 /* Currently nothing to do. */
2249 hash_scan_call (x
, insn
)
2250 rtx x ATTRIBUTE_UNUSED
, insn ATTRIBUTE_UNUSED
;
2252 /* Currently nothing to do. */
2255 /* Process INSN and add hash table entries as appropriate.
2257 Only available expressions that set a single pseudo-reg are recorded.
2259 Single sets in a PARALLEL could be handled, but it's an extra complication
2260 that isn't dealt with right now. The trick is handling the CLOBBERs that
2261 are also in the PARALLEL. Later.
2263 If SET_P is non-zero, this is for the assignment hash table,
2264 otherwise it is for the expression hash table.
2265 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
2266 not record any expressions. */
2269 hash_scan_insn (insn
, set_p
, in_libcall_block
)
2272 int in_libcall_block
;
2274 rtx pat
= PATTERN (insn
);
2277 if (in_libcall_block
)
2280 /* Pick out the sets of INSN and for other forms of instructions record
2281 what's been modified. */
2283 if (GET_CODE (pat
) == SET
)
2284 hash_scan_set (pat
, insn
, set_p
);
2285 else if (GET_CODE (pat
) == PARALLEL
)
2286 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2288 rtx x
= XVECEXP (pat
, 0, i
);
2290 if (GET_CODE (x
) == SET
)
2291 hash_scan_set (x
, insn
, set_p
);
2292 else if (GET_CODE (x
) == CLOBBER
)
2293 hash_scan_clobber (x
, insn
);
2294 else if (GET_CODE (x
) == CALL
)
2295 hash_scan_call (x
, insn
);
2298 else if (GET_CODE (pat
) == CLOBBER
)
2299 hash_scan_clobber (pat
, insn
);
2300 else if (GET_CODE (pat
) == CALL
)
2301 hash_scan_call (pat
, insn
);
2305 dump_hash_table (file
, name
, table
, table_size
, total_size
)
2308 struct expr
**table
;
2309 int table_size
, total_size
;
2312 /* Flattened out table, so it's printed in proper order. */
2313 struct expr
**flat_table
;
2314 unsigned int *hash_val
;
2318 = (struct expr
**) xcalloc (total_size
, sizeof (struct expr
*));
2319 hash_val
= (unsigned int *) xmalloc (total_size
* sizeof (unsigned int));
2321 for (i
= 0; i
< table_size
; i
++)
2322 for (expr
= table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
2324 flat_table
[expr
->bitmap_index
] = expr
;
2325 hash_val
[expr
->bitmap_index
] = i
;
2328 fprintf (file
, "%s hash table (%d buckets, %d entries)\n",
2329 name
, table_size
, total_size
);
2331 for (i
= 0; i
< total_size
; i
++)
2332 if (flat_table
[i
] != 0)
2334 expr
= flat_table
[i
];
2335 fprintf (file
, "Index %d (hash value %d)\n ",
2336 expr
->bitmap_index
, hash_val
[i
]);
2337 print_rtl (file
, expr
->expr
);
2338 fprintf (file
, "\n");
2341 fprintf (file
, "\n");
2347 /* Record register first/last/block set information for REGNO in INSN.
2349 first_set records the first place in the block where the register
2350 is set and is used to compute "anticipatability".
2352 last_set records the last place in the block where the register
2353 is set and is used to compute "availability".
2355 last_bb records the block for which first_set and last_set are
2356 valid, as a quick test to invalidate them.
2358 reg_set_in_block records whether the register is set in the block
2359 and is used to compute "transparency". */
2362 record_last_reg_set_info (insn
, regno
)
2366 struct reg_avail_info
*info
= ®_avail_info
[regno
];
2367 int cuid
= INSN_CUID (insn
);
2369 info
->last_set
= cuid
;
2370 if (info
->last_bb
!= current_bb
)
2372 info
->last_bb
= current_bb
;
2373 info
->first_set
= cuid
;
2374 SET_BIT (reg_set_in_block
[current_bb
->index
], regno
);
2379 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
2380 Note we store a pair of elements in the list, so they have to be
2381 taken off pairwise. */
2384 canon_list_insert (dest
, unused1
, v_insn
)
2385 rtx dest ATTRIBUTE_UNUSED
;
2386 rtx unused1 ATTRIBUTE_UNUSED
;
2389 rtx dest_addr
, insn
;
2392 while (GET_CODE (dest
) == SUBREG
2393 || GET_CODE (dest
) == ZERO_EXTRACT
2394 || GET_CODE (dest
) == SIGN_EXTRACT
2395 || GET_CODE (dest
) == STRICT_LOW_PART
)
2396 dest
= XEXP (dest
, 0);
2398 /* If DEST is not a MEM, then it will not conflict with a load. Note
2399 that function calls are assumed to clobber memory, but are handled
2402 if (GET_CODE (dest
) != MEM
)
2405 dest_addr
= get_addr (XEXP (dest
, 0));
2406 dest_addr
= canon_rtx (dest_addr
);
2407 insn
= (rtx
) v_insn
;
2408 bb
= BLOCK_NUM (insn
);
2410 canon_modify_mem_list
[bb
] =
2411 alloc_EXPR_LIST (VOIDmode
, dest_addr
, canon_modify_mem_list
[bb
]);
2412 canon_modify_mem_list
[bb
] =
2413 alloc_EXPR_LIST (VOIDmode
, dest
, canon_modify_mem_list
[bb
]);
2414 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2417 /* Record memory modification information for INSN. We do not actually care
2418 about the memory location(s) that are set, or even how they are set (consider
2419 a CALL_INSN). We merely need to record which insns modify memory. */
2422 record_last_mem_set_info (insn
)
2425 int bb
= BLOCK_NUM (insn
);
2427 /* load_killed_in_block_p will handle the case of calls clobbering
2429 modify_mem_list
[bb
] = alloc_INSN_LIST (insn
, modify_mem_list
[bb
]);
2430 bitmap_set_bit (modify_mem_list_set
, bb
);
2432 if (GET_CODE (insn
) == CALL_INSN
)
2434 /* Note that traversals of this loop (other than for free-ing)
2435 will break after encountering a CALL_INSN. So, there's no
2436 need to insert a pair of items, as canon_list_insert does. */
2437 canon_modify_mem_list
[bb
] =
2438 alloc_INSN_LIST (insn
, canon_modify_mem_list
[bb
]);
2439 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2442 note_stores (PATTERN (insn
), canon_list_insert
, (void*) insn
);
2445 /* Called from compute_hash_table via note_stores to handle one
2446 SET or CLOBBER in an insn. DATA is really the instruction in which
2447 the SET is taking place. */
2450 record_last_set_info (dest
, setter
, data
)
2451 rtx dest
, setter ATTRIBUTE_UNUSED
;
2454 rtx last_set_insn
= (rtx
) data
;
2456 if (GET_CODE (dest
) == SUBREG
)
2457 dest
= SUBREG_REG (dest
);
2459 if (GET_CODE (dest
) == REG
)
2460 record_last_reg_set_info (last_set_insn
, REGNO (dest
));
2461 else if (GET_CODE (dest
) == MEM
2462 /* Ignore pushes, they clobber nothing. */
2463 && ! push_operand (dest
, GET_MODE (dest
)))
2464 record_last_mem_set_info (last_set_insn
);
2467 /* Top level function to create an expression or assignment hash table.
2469 Expression entries are placed in the hash table if
2470 - they are of the form (set (pseudo-reg) src),
2471 - src is something we want to perform GCSE on,
2472 - none of the operands are subsequently modified in the block
2474 Assignment entries are placed in the hash table if
2475 - they are of the form (set (pseudo-reg) src),
2476 - src is something we want to perform const/copy propagation on,
2477 - none of the operands or target are subsequently modified in the block
2479 Currently src must be a pseudo-reg or a const_int.
2481 F is the first insn.
2482 SET_P is non-zero for computing the assignment hash table. */
2485 compute_hash_table (set_p
)
2490 /* While we compute the hash table we also compute a bit array of which
2491 registers are set in which blocks.
2492 ??? This isn't needed during const/copy propagation, but it's cheap to
2494 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
2496 /* re-Cache any INSN_LIST nodes we have allocated. */
2497 clear_modify_mem_tables ();
2498 /* Some working arrays used to track first and last set in each block. */
2499 reg_avail_info
= (struct reg_avail_info
*)
2500 gmalloc (max_gcse_regno
* sizeof (struct reg_avail_info
));
2502 for (i
= 0; i
< max_gcse_regno
; ++i
)
2503 reg_avail_info
[i
].last_bb
= NULL
;
2505 FOR_EACH_BB (current_bb
)
2509 int in_libcall_block
;
2511 /* First pass over the instructions records information used to
2512 determine when registers and memory are first and last set.
2513 ??? hard-reg reg_set_in_block computation
2514 could be moved to compute_sets since they currently don't change. */
2516 for (insn
= current_bb
->head
;
2517 insn
&& insn
!= NEXT_INSN (current_bb
->end
);
2518 insn
= NEXT_INSN (insn
))
2520 if (! INSN_P (insn
))
2523 if (GET_CODE (insn
) == CALL_INSN
)
2525 bool clobbers_all
= false;
2526 #ifdef NON_SAVING_SETJMP
2527 if (NON_SAVING_SETJMP
2528 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
2529 clobbers_all
= true;
2532 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2534 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2535 record_last_reg_set_info (insn
, regno
);
2540 note_stores (PATTERN (insn
), record_last_set_info
, insn
);
2543 /* The next pass builds the hash table. */
2545 for (insn
= current_bb
->head
, in_libcall_block
= 0;
2546 insn
&& insn
!= NEXT_INSN (current_bb
->end
);
2547 insn
= NEXT_INSN (insn
))
2550 if (find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2551 in_libcall_block
= 1;
2552 else if (set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2553 in_libcall_block
= 0;
2554 hash_scan_insn (insn
, set_p
, in_libcall_block
);
2555 if (!set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2556 in_libcall_block
= 0;
2560 free (reg_avail_info
);
2561 reg_avail_info
= NULL
;
2564 /* Allocate space for the set hash table.
2565 N_INSNS is the number of instructions in the function.
2566 It is used to determine the number of buckets to use. */
2569 alloc_set_hash_table (n_insns
)
2574 set_hash_table_size
= n_insns
/ 4;
2575 if (set_hash_table_size
< 11)
2576 set_hash_table_size
= 11;
2578 /* Attempt to maintain efficient use of hash table.
2579 Making it an odd number is simplest for now.
2580 ??? Later take some measurements. */
2581 set_hash_table_size
|= 1;
2582 n
= set_hash_table_size
* sizeof (struct expr
*);
2583 set_hash_table
= (struct expr
**) gmalloc (n
);
2586 /* Free things allocated by alloc_set_hash_table. */
2589 free_set_hash_table ()
2591 free (set_hash_table
);
2594 /* Compute the hash table for doing copy/const propagation. */
2597 compute_set_hash_table ()
2599 /* Initialize count of number of entries in hash table. */
2601 memset ((char *) set_hash_table
, 0,
2602 set_hash_table_size
* sizeof (struct expr
*));
2604 compute_hash_table (1);
2607 /* Allocate space for the expression hash table.
2608 N_INSNS is the number of instructions in the function.
2609 It is used to determine the number of buckets to use. */
2612 alloc_expr_hash_table (n_insns
)
2613 unsigned int n_insns
;
2617 expr_hash_table_size
= n_insns
/ 2;
2618 /* Make sure the amount is usable. */
2619 if (expr_hash_table_size
< 11)
2620 expr_hash_table_size
= 11;
2622 /* Attempt to maintain efficient use of hash table.
2623 Making it an odd number is simplest for now.
2624 ??? Later take some measurements. */
2625 expr_hash_table_size
|= 1;
2626 n
= expr_hash_table_size
* sizeof (struct expr
*);
2627 expr_hash_table
= (struct expr
**) gmalloc (n
);
2630 /* Free things allocated by alloc_expr_hash_table. */
2633 free_expr_hash_table ()
2635 free (expr_hash_table
);
2638 /* Compute the hash table for doing GCSE. */
2641 compute_expr_hash_table ()
2643 /* Initialize count of number of entries in hash table. */
2645 memset ((char *) expr_hash_table
, 0,
2646 expr_hash_table_size
* sizeof (struct expr
*));
2648 compute_hash_table (0);
2651 /* Expression tracking support. */
2653 /* Lookup pattern PAT in the expression table.
2654 The result is a pointer to the table entry, or NULL if not found. */
2656 static struct expr
*
2660 int do_not_record_p
;
2661 unsigned int hash
= hash_expr (pat
, GET_MODE (pat
), &do_not_record_p
,
2662 expr_hash_table_size
);
2665 if (do_not_record_p
)
2668 expr
= expr_hash_table
[hash
];
2670 while (expr
&& ! expr_equiv_p (expr
->expr
, pat
))
2671 expr
= expr
->next_same_hash
;
2676 /* Lookup REGNO in the set table. If PAT is non-NULL look for the entry that
2677 matches it, otherwise return the first entry for REGNO. The result is a
2678 pointer to the table entry, or NULL if not found. */
2680 static struct expr
*
2681 lookup_set (regno
, pat
)
2685 unsigned int hash
= hash_set (regno
, set_hash_table_size
);
2688 expr
= set_hash_table
[hash
];
2692 while (expr
&& ! expr_equiv_p (expr
->expr
, pat
))
2693 expr
= expr
->next_same_hash
;
2697 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
)
2698 expr
= expr
->next_same_hash
;
2704 /* Return the next entry for REGNO in list EXPR. */
2706 static struct expr
*
2707 next_set (regno
, expr
)
2712 expr
= expr
->next_same_hash
;
2713 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
);
2718 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2719 types may be mixed. */
2722 free_insn_expr_list_list (listp
)
2727 for (list
= *listp
; list
; list
= next
)
2729 next
= XEXP (list
, 1);
2730 if (GET_CODE (list
) == EXPR_LIST
)
2731 free_EXPR_LIST_node (list
);
2733 free_INSN_LIST_node (list
);
2739 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2741 clear_modify_mem_tables ()
2745 EXECUTE_IF_SET_IN_BITMAP
2746 (modify_mem_list_set
, 0, i
, free_INSN_LIST_list (modify_mem_list
+ i
));
2747 bitmap_clear (modify_mem_list_set
);
2749 EXECUTE_IF_SET_IN_BITMAP
2750 (canon_modify_mem_list_set
, 0, i
,
2751 free_insn_expr_list_list (canon_modify_mem_list
+ i
));
2752 bitmap_clear (canon_modify_mem_list_set
);
2755 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2758 free_modify_mem_tables ()
2760 clear_modify_mem_tables ();
2761 free (modify_mem_list
);
2762 free (canon_modify_mem_list
);
2763 modify_mem_list
= 0;
2764 canon_modify_mem_list
= 0;
2767 /* Reset tables used to keep track of what's still available [since the
2768 start of the block]. */
2771 reset_opr_set_tables ()
2773 /* Maintain a bitmap of which regs have been set since beginning of
2775 CLEAR_REG_SET (reg_set_bitmap
);
2777 /* Also keep a record of the last instruction to modify memory.
2778 For now this is very trivial, we only record whether any memory
2779 location has been modified. */
2780 clear_modify_mem_tables ();
2783 /* Return non-zero if the operands of X are not set before INSN in
2784 INSN's basic block. */
2787 oprs_not_set_p (x
, insn
)
2797 code
= GET_CODE (x
);
2813 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn
),
2814 INSN_CUID (insn
), x
, 0))
2817 return oprs_not_set_p (XEXP (x
, 0), insn
);
2820 return ! REGNO_REG_SET_P (reg_set_bitmap
, REGNO (x
));
2826 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2830 /* If we are about to do the last recursive call
2831 needed at this level, change it into iteration.
2832 This function is called enough to be worth it. */
2834 return oprs_not_set_p (XEXP (x
, i
), insn
);
2836 if (! oprs_not_set_p (XEXP (x
, i
), insn
))
2839 else if (fmt
[i
] == 'E')
2840 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2841 if (! oprs_not_set_p (XVECEXP (x
, i
, j
), insn
))
2848 /* Mark things set by a CALL. */
2854 if (! CONST_OR_PURE_CALL_P (insn
))
2855 record_last_mem_set_info (insn
);
2858 /* Mark things set by a SET. */
2861 mark_set (pat
, insn
)
2864 rtx dest
= SET_DEST (pat
);
2866 while (GET_CODE (dest
) == SUBREG
2867 || GET_CODE (dest
) == ZERO_EXTRACT
2868 || GET_CODE (dest
) == SIGN_EXTRACT
2869 || GET_CODE (dest
) == STRICT_LOW_PART
)
2870 dest
= XEXP (dest
, 0);
2872 if (GET_CODE (dest
) == REG
)
2873 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (dest
));
2874 else if (GET_CODE (dest
) == MEM
)
2875 record_last_mem_set_info (insn
);
2877 if (GET_CODE (SET_SRC (pat
)) == CALL
)
2881 /* Record things set by a CLOBBER. */
2884 mark_clobber (pat
, insn
)
2887 rtx clob
= XEXP (pat
, 0);
2889 while (GET_CODE (clob
) == SUBREG
|| GET_CODE (clob
) == STRICT_LOW_PART
)
2890 clob
= XEXP (clob
, 0);
2892 if (GET_CODE (clob
) == REG
)
2893 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (clob
));
2895 record_last_mem_set_info (insn
);
2898 /* Record things set by INSN.
2899 This data is used by oprs_not_set_p. */
2902 mark_oprs_set (insn
)
2905 rtx pat
= PATTERN (insn
);
2908 if (GET_CODE (pat
) == SET
)
2909 mark_set (pat
, insn
);
2910 else if (GET_CODE (pat
) == PARALLEL
)
2911 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2913 rtx x
= XVECEXP (pat
, 0, i
);
2915 if (GET_CODE (x
) == SET
)
2917 else if (GET_CODE (x
) == CLOBBER
)
2918 mark_clobber (x
, insn
);
2919 else if (GET_CODE (x
) == CALL
)
2923 else if (GET_CODE (pat
) == CLOBBER
)
2924 mark_clobber (pat
, insn
);
2925 else if (GET_CODE (pat
) == CALL
)
2930 /* Classic GCSE reaching definition support. */
2932 /* Allocate reaching def variables. */
2935 alloc_rd_mem (n_blocks
, n_insns
)
2936 int n_blocks
, n_insns
;
2938 rd_kill
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2939 sbitmap_vector_zero (rd_kill
, n_blocks
);
2941 rd_gen
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2942 sbitmap_vector_zero (rd_gen
, n_blocks
);
2944 reaching_defs
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2945 sbitmap_vector_zero (reaching_defs
, n_blocks
);
2947 rd_out
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_insns
);
2948 sbitmap_vector_zero (rd_out
, n_blocks
);
2951 /* Free reaching def variables. */
2956 sbitmap_vector_free (rd_kill
);
2957 sbitmap_vector_free (rd_gen
);
2958 sbitmap_vector_free (reaching_defs
);
2959 sbitmap_vector_free (rd_out
);
2962 /* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
2965 handle_rd_kill_set (insn
, regno
, bb
)
2970 struct reg_set
*this_reg
;
2972 for (this_reg
= reg_set_table
[regno
]; this_reg
; this_reg
= this_reg
->next
)
2973 if (BLOCK_NUM (this_reg
->insn
) != BLOCK_NUM (insn
))
2974 SET_BIT (rd_kill
[bb
->index
], INSN_CUID (this_reg
->insn
));
2977 /* Compute the set of kill's for reaching definitions. */
2988 For each set bit in `gen' of the block (i.e each insn which
2989 generates a definition in the block)
2990 Call the reg set by the insn corresponding to that bit regx
2991 Look at the linked list starting at reg_set_table[regx]
2992 For each setting of regx in the linked list, which is not in
2994 Set the bit in `kill' corresponding to that insn. */
2996 for (cuid
= 0; cuid
< max_cuid
; cuid
++)
2997 if (TEST_BIT (rd_gen
[bb
->index
], cuid
))
2999 rtx insn
= CUID_INSN (cuid
);
3000 rtx pat
= PATTERN (insn
);
3002 if (GET_CODE (insn
) == CALL_INSN
)
3004 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
3005 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
3006 handle_rd_kill_set (insn
, regno
, bb
);
3009 if (GET_CODE (pat
) == PARALLEL
)
3011 for (i
= XVECLEN (pat
, 0) - 1; i
>= 0; i
--)
3013 enum rtx_code code
= GET_CODE (XVECEXP (pat
, 0, i
));
3015 if ((code
== SET
|| code
== CLOBBER
)
3016 && GET_CODE (XEXP (XVECEXP (pat
, 0, i
), 0)) == REG
)
3017 handle_rd_kill_set (insn
,
3018 REGNO (XEXP (XVECEXP (pat
, 0, i
), 0)),
3022 else if (GET_CODE (pat
) == SET
&& GET_CODE (SET_DEST (pat
)) == REG
)
3023 /* Each setting of this register outside of this block
3024 must be marked in the set of kills in this block. */
3025 handle_rd_kill_set (insn
, REGNO (SET_DEST (pat
)), bb
);
3029 /* Compute the reaching definitions as in
3030 Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
3031 Chapter 10. It is the same algorithm as used for computing available
3032 expressions but applied to the gens and kills of reaching definitions. */
3037 int changed
, passes
;
3041 sbitmap_copy (rd_out
[bb
->index
] /*dst*/, rd_gen
[bb
->index
] /*src*/);
3050 sbitmap_union_of_preds (reaching_defs
[bb
->index
], rd_out
, bb
->index
);
3051 changed
|= sbitmap_union_of_diff_cg (rd_out
[bb
->index
], rd_gen
[bb
->index
],
3052 reaching_defs
[bb
->index
], rd_kill
[bb
->index
]);
3058 fprintf (gcse_file
, "reaching def computation: %d passes\n", passes
);
3061 /* Classic GCSE available expression support. */
3063 /* Allocate memory for available expression computation. */
3066 alloc_avail_expr_mem (n_blocks
, n_exprs
)
3067 int n_blocks
, n_exprs
;
3069 ae_kill
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3070 sbitmap_vector_zero (ae_kill
, n_blocks
);
3072 ae_gen
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3073 sbitmap_vector_zero (ae_gen
, n_blocks
);
3075 ae_in
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3076 sbitmap_vector_zero (ae_in
, n_blocks
);
3078 ae_out
= (sbitmap
*) sbitmap_vector_alloc (n_blocks
, n_exprs
);
3079 sbitmap_vector_zero (ae_out
, n_blocks
);
3083 free_avail_expr_mem ()
3085 sbitmap_vector_free (ae_kill
);
3086 sbitmap_vector_free (ae_gen
);
3087 sbitmap_vector_free (ae_in
);
3088 sbitmap_vector_free (ae_out
);
3091 /* Compute the set of available expressions generated in each basic block. */
3100 /* For each recorded occurrence of each expression, set ae_gen[bb][expr].
3101 This is all we have to do because an expression is not recorded if it
3102 is not available, and the only expressions we want to work with are the
3103 ones that are recorded. */
3104 for (i
= 0; i
< expr_hash_table_size
; i
++)
3105 for (expr
= expr_hash_table
[i
]; expr
!= 0; expr
= expr
->next_same_hash
)
3106 for (occr
= expr
->avail_occr
; occr
!= 0; occr
= occr
->next
)
3107 SET_BIT (ae_gen
[BLOCK_NUM (occr
->insn
)], expr
->bitmap_index
);
3110 /* Return non-zero if expression X is killed in BB. */
3113 expr_killed_p (x
, bb
)
3124 code
= GET_CODE (x
);
3128 return TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
));
3131 if (load_killed_in_block_p (bb
, get_max_uid () + 1, x
, 0))
3134 return expr_killed_p (XEXP (x
, 0), bb
);
3152 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3156 /* If we are about to do the last recursive call
3157 needed at this level, change it into iteration.
3158 This function is called enough to be worth it. */
3160 return expr_killed_p (XEXP (x
, i
), bb
);
3161 else if (expr_killed_p (XEXP (x
, i
), bb
))
3164 else if (fmt
[i
] == 'E')
3165 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3166 if (expr_killed_p (XVECEXP (x
, i
, j
), bb
))
3173 /* Compute the set of available expressions killed in each basic block. */
3176 compute_ae_kill (ae_gen
, ae_kill
)
3177 sbitmap
*ae_gen
, *ae_kill
;
3184 for (i
= 0; i
< expr_hash_table_size
; i
++)
3185 for (expr
= expr_hash_table
[i
]; expr
; expr
= expr
->next_same_hash
)
3187 /* Skip EXPR if generated in this block. */
3188 if (TEST_BIT (ae_gen
[bb
->index
], expr
->bitmap_index
))
3191 if (expr_killed_p (expr
->expr
, bb
))
3192 SET_BIT (ae_kill
[bb
->index
], expr
->bitmap_index
);
3196 /* Actually perform the Classic GCSE optimizations. */
3198 /* Return non-zero if occurrence OCCR of expression EXPR reaches block BB.
3200 CHECK_SELF_LOOP is non-zero if we should consider a block reaching itself
3201 as a positive reach. We want to do this when there are two computations
3202 of the expression in the block.
3204 VISITED is a pointer to a working buffer for tracking which BB's have
3205 been visited. It is NULL for the top-level call.
3207 We treat reaching expressions that go through blocks containing the same
3208 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3209 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3210 2 as not reaching. The intent is to improve the probability of finding
3211 only one reaching expression and to reduce register lifetimes by picking
3212 the closest such expression. */
3215 expr_reaches_here_p_work (occr
, expr
, bb
, check_self_loop
, visited
)
3219 int check_self_loop
;
3224 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
3226 basic_block pred_bb
= pred
->src
;
3228 if (visited
[pred_bb
->index
])
3229 /* This predecessor has already been visited. Nothing to do. */
3231 else if (pred_bb
== bb
)
3233 /* BB loops on itself. */
3235 && TEST_BIT (ae_gen
[pred_bb
->index
], expr
->bitmap_index
)
3236 && BLOCK_NUM (occr
->insn
) == pred_bb
->index
)
3239 visited
[pred_bb
->index
] = 1;
3242 /* Ignore this predecessor if it kills the expression. */
3243 else if (TEST_BIT (ae_kill
[pred_bb
->index
], expr
->bitmap_index
))
3244 visited
[pred_bb
->index
] = 1;
3246 /* Does this predecessor generate this expression? */
3247 else if (TEST_BIT (ae_gen
[pred_bb
->index
], expr
->bitmap_index
))
3249 /* Is this the occurrence we're looking for?
3250 Note that there's only one generating occurrence per block
3251 so we just need to check the block number. */
3252 if (BLOCK_NUM (occr
->insn
) == pred_bb
->index
)
3255 visited
[pred_bb
->index
] = 1;
3258 /* Neither gen nor kill. */
3261 visited
[pred_bb
->index
] = 1;
3262 if (expr_reaches_here_p_work (occr
, expr
, pred_bb
, check_self_loop
,
3269 /* All paths have been checked. */
3273 /* This wrapper for expr_reaches_here_p_work() is to ensure that any
3274 memory allocated for that function is returned. */
3277 expr_reaches_here_p (occr
, expr
, bb
, check_self_loop
)
3281 int check_self_loop
;
3284 char *visited
= (char *) xcalloc (last_basic_block
, 1);
3286 rval
= expr_reaches_here_p_work (occr
, expr
, bb
, check_self_loop
, visited
);
3292 /* Return the instruction that computes EXPR that reaches INSN's basic block.
3293 If there is more than one such instruction, return NULL.
3295 Called only by handle_avail_expr. */
3298 computing_insn (expr
, insn
)
3302 basic_block bb
= BLOCK_FOR_INSN (insn
);
3304 if (expr
->avail_occr
->next
== NULL
)
3306 if (BLOCK_FOR_INSN (expr
->avail_occr
->insn
) == bb
)
3307 /* The available expression is actually itself
3308 (i.e. a loop in the flow graph) so do nothing. */
3311 /* (FIXME) Case that we found a pattern that was created by
3312 a substitution that took place. */
3313 return expr
->avail_occr
->insn
;
3317 /* Pattern is computed more than once.
3318 Search backwards from this insn to see how many of these
3319 computations actually reach this insn. */
3321 rtx insn_computes_expr
= NULL
;
3324 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
3326 if (BLOCK_FOR_INSN (occr
->insn
) == bb
)
3328 /* The expression is generated in this block.
3329 The only time we care about this is when the expression
3330 is generated later in the block [and thus there's a loop].
3331 We let the normal cse pass handle the other cases. */
3332 if (INSN_CUID (insn
) < INSN_CUID (occr
->insn
)
3333 && expr_reaches_here_p (occr
, expr
, bb
, 1))
3339 insn_computes_expr
= occr
->insn
;
3342 else if (expr_reaches_here_p (occr
, expr
, bb
, 0))
3348 insn_computes_expr
= occr
->insn
;
3352 if (insn_computes_expr
== NULL
)
3355 return insn_computes_expr
;
3359 /* Return non-zero if the definition in DEF_INSN can reach INSN.
3360 Only called by can_disregard_other_sets. */
3363 def_reaches_here_p (insn
, def_insn
)
3368 if (TEST_BIT (reaching_defs
[BLOCK_NUM (insn
)], INSN_CUID (def_insn
)))
3371 if (BLOCK_NUM (insn
) == BLOCK_NUM (def_insn
))
3373 if (INSN_CUID (def_insn
) < INSN_CUID (insn
))
3375 if (GET_CODE (PATTERN (def_insn
)) == PARALLEL
)
3377 else if (GET_CODE (PATTERN (def_insn
)) == CLOBBER
)
3378 reg
= XEXP (PATTERN (def_insn
), 0);
3379 else if (GET_CODE (PATTERN (def_insn
)) == SET
)
3380 reg
= SET_DEST (PATTERN (def_insn
));
3384 return ! reg_set_between_p (reg
, NEXT_INSN (def_insn
), insn
);
3393 /* Return non-zero if *ADDR_THIS_REG can only have one value at INSN. The
3394 value returned is the number of definitions that reach INSN. Returning a
3395 value of zero means that [maybe] more than one definition reaches INSN and
3396 the caller can't perform whatever optimization it is trying. i.e. it is
3397 always safe to return zero. */
3400 can_disregard_other_sets (addr_this_reg
, insn
, for_combine
)
3401 struct reg_set
**addr_this_reg
;
3405 int number_of_reaching_defs
= 0;
3406 struct reg_set
*this_reg
;
3408 for (this_reg
= *addr_this_reg
; this_reg
!= 0; this_reg
= this_reg
->next
)
3409 if (def_reaches_here_p (insn
, this_reg
->insn
))
3411 number_of_reaching_defs
++;
3412 /* Ignore parallels for now. */
3413 if (GET_CODE (PATTERN (this_reg
->insn
)) == PARALLEL
)
3417 && (GET_CODE (PATTERN (this_reg
->insn
)) == CLOBBER
3418 || ! rtx_equal_p (SET_SRC (PATTERN (this_reg
->insn
)),
3419 SET_SRC (PATTERN (insn
)))))
3420 /* A setting of the reg to a different value reaches INSN. */
3423 if (number_of_reaching_defs
> 1)
3425 /* If in this setting the value the register is being set to is
3426 equal to the previous value the register was set to and this
3427 setting reaches the insn we are trying to do the substitution
3428 on then we are ok. */
3429 if (GET_CODE (PATTERN (this_reg
->insn
)) == CLOBBER
)
3431 else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg
->insn
)),
3432 SET_SRC (PATTERN (insn
))))
3436 *addr_this_reg
= this_reg
;
3439 return number_of_reaching_defs
;
3442 /* Expression computed by insn is available and the substitution is legal,
3443 so try to perform the substitution.
3445 The result is non-zero if any changes were made. */
3448 handle_avail_expr (insn
, expr
)
3452 rtx pat
, insn_computes_expr
, expr_set
;
3454 struct reg_set
*this_reg
;
3455 int found_setting
, use_src
;
3458 /* We only handle the case where one computation of the expression
3459 reaches this instruction. */
3460 insn_computes_expr
= computing_insn (expr
, insn
);
3461 if (insn_computes_expr
== NULL
)
3463 expr_set
= single_set (insn_computes_expr
);
3470 /* At this point we know only one computation of EXPR outside of this
3471 block reaches this insn. Now try to find a register that the
3472 expression is computed into. */
3473 if (GET_CODE (SET_SRC (expr_set
)) == REG
)
3475 /* This is the case when the available expression that reaches
3476 here has already been handled as an available expression. */
3477 unsigned int regnum_for_replacing
3478 = REGNO (SET_SRC (expr_set
));
3480 /* If the register was created by GCSE we can't use `reg_set_table',
3481 however we know it's set only once. */
3482 if (regnum_for_replacing
>= max_gcse_regno
3483 /* If the register the expression is computed into is set only once,
3484 or only one set reaches this insn, we can use it. */
3485 || (((this_reg
= reg_set_table
[regnum_for_replacing
]),
3486 this_reg
->next
== NULL
)
3487 || can_disregard_other_sets (&this_reg
, insn
, 0)))
3496 unsigned int regnum_for_replacing
3497 = REGNO (SET_DEST (expr_set
));
3499 /* This shouldn't happen. */
3500 if (regnum_for_replacing
>= max_gcse_regno
)
3503 this_reg
= reg_set_table
[regnum_for_replacing
];
3505 /* If the register the expression is computed into is set only once,
3506 or only one set reaches this insn, use it. */
3507 if (this_reg
->next
== NULL
3508 || can_disregard_other_sets (&this_reg
, insn
, 0))
3514 pat
= PATTERN (insn
);
3516 to
= SET_SRC (expr_set
);
3518 to
= SET_DEST (expr_set
);
3519 changed
= validate_change (insn
, &SET_SRC (pat
), to
, 0);
3521 /* We should be able to ignore the return code from validate_change but
3522 to play it safe we check. */
3526 if (gcse_file
!= NULL
)
3528 fprintf (gcse_file
, "GCSE: Replacing the source in insn %d with",
3530 fprintf (gcse_file
, " reg %d %s insn %d\n",
3531 REGNO (to
), use_src
? "from" : "set in",
3532 INSN_UID (insn_computes_expr
));
3537 /* The register that the expr is computed into is set more than once. */
3538 else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
3540 /* Insert an insn after insnx that copies the reg set in insnx
3541 into a new pseudo register call this new register REGN.
3542 From insnb until end of basic block or until REGB is set
3543 replace all uses of REGB with REGN. */
3546 to
= gen_reg_rtx (GET_MODE (SET_DEST (expr_set
)));
3548 /* Generate the new insn. */
3549 /* ??? If the change fails, we return 0, even though we created
3550 an insn. I think this is ok. */
3552 = emit_insn_after (gen_rtx_SET (VOIDmode
, to
,
3553 SET_DEST (expr_set
)),
3554 insn_computes_expr
);
3556 /* Keep register set table up to date. */
3557 record_one_set (REGNO (to
), new_insn
);
3559 gcse_create_count
++;
3560 if (gcse_file
!= NULL
)
3562 fprintf (gcse_file
, "GCSE: Creating insn %d to copy value of reg %d",
3563 INSN_UID (NEXT_INSN (insn_computes_expr
)),
3564 REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr
)))));
3565 fprintf (gcse_file
, ", computed in insn %d,\n",
3566 INSN_UID (insn_computes_expr
));
3567 fprintf (gcse_file
, " into newly allocated reg %d\n",
3571 pat
= PATTERN (insn
);
3573 /* Do register replacement for INSN. */
3574 changed
= validate_change (insn
, &SET_SRC (pat
),
3576 (NEXT_INSN (insn_computes_expr
))),
3579 /* We should be able to ignore the return code from validate_change but
3580 to play it safe we check. */
3584 if (gcse_file
!= NULL
)
3587 "GCSE: Replacing the source in insn %d with reg %d ",
3589 REGNO (SET_DEST (PATTERN (NEXT_INSN
3590 (insn_computes_expr
)))));
3591 fprintf (gcse_file
, "set in insn %d\n",
3592 INSN_UID (insn_computes_expr
));
3600 /* Perform classic GCSE. This is called by one_classic_gcse_pass after all
3601 the dataflow analysis has been done.
3603 The result is non-zero if a change was made. */
3612 /* Note we start at block 1. */
3614 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3618 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
3620 /* Reset tables used to keep track of what's still valid [since the
3621 start of the block]. */
3622 reset_opr_set_tables ();
3624 for (insn
= bb
->head
;
3625 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
3626 insn
= NEXT_INSN (insn
))
3628 /* Is insn of form (set (pseudo-reg) ...)? */
3629 if (GET_CODE (insn
) == INSN
3630 && GET_CODE (PATTERN (insn
)) == SET
3631 && GET_CODE (SET_DEST (PATTERN (insn
))) == REG
3632 && REGNO (SET_DEST (PATTERN (insn
))) >= FIRST_PSEUDO_REGISTER
)
3634 rtx pat
= PATTERN (insn
);
3635 rtx src
= SET_SRC (pat
);
3638 if (want_to_gcse_p (src
)
3639 /* Is the expression recorded? */
3640 && ((expr
= lookup_expr (src
)) != NULL
)
3641 /* Is the expression available [at the start of the
3643 && TEST_BIT (ae_in
[bb
->index
], expr
->bitmap_index
)
3644 /* Are the operands unchanged since the start of the
3646 && oprs_not_set_p (src
, insn
))
3647 changed
|= handle_avail_expr (insn
, expr
);
3650 /* Keep track of everything modified by this insn. */
3651 /* ??? Need to be careful w.r.t. mods done to INSN. */
3653 mark_oprs_set (insn
);
3660 /* Top level routine to perform one classic GCSE pass.
3662 Return non-zero if a change was made. */
3665 one_classic_gcse_pass (pass
)
3670 gcse_subst_count
= 0;
3671 gcse_create_count
= 0;
3673 alloc_expr_hash_table (max_cuid
);
3674 alloc_rd_mem (last_basic_block
, max_cuid
);
3675 compute_expr_hash_table ();
3677 dump_hash_table (gcse_file
, "Expression", expr_hash_table
,
3678 expr_hash_table_size
, n_exprs
);
3684 alloc_avail_expr_mem (last_basic_block
, n_exprs
);
3686 compute_ae_kill (ae_gen
, ae_kill
);
3687 compute_available (ae_gen
, ae_kill
, ae_out
, ae_in
);
3688 changed
= classic_gcse ();
3689 free_avail_expr_mem ();
3693 free_expr_hash_table ();
3697 fprintf (gcse_file
, "\n");
3698 fprintf (gcse_file
, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
3699 current_function_name
, pass
, bytes_used
, gcse_subst_count
);
3700 fprintf (gcse_file
, "%d insns created\n", gcse_create_count
);
3706 /* Compute copy/constant propagation working variables. */
3708 /* Local properties of assignments. */
3709 static sbitmap
*cprop_pavloc
;
3710 static sbitmap
*cprop_absaltered
;
3712 /* Global properties of assignments (computed from the local properties). */
3713 static sbitmap
*cprop_avin
;
3714 static sbitmap
*cprop_avout
;
3716 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
3717 basic blocks. N_SETS is the number of sets. */
3720 alloc_cprop_mem (n_blocks
, n_sets
)
3721 int n_blocks
, n_sets
;
3723 cprop_pavloc
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3724 cprop_absaltered
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3726 cprop_avin
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3727 cprop_avout
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3730 /* Free vars used by copy/const propagation. */
3735 sbitmap_vector_free (cprop_pavloc
);
3736 sbitmap_vector_free (cprop_absaltered
);
3737 sbitmap_vector_free (cprop_avin
);
3738 sbitmap_vector_free (cprop_avout
);
3741 /* For each block, compute whether X is transparent. X is either an
3742 expression or an assignment [though we don't care which, for this context
3743 an assignment is treated as an expression]. For each block where an
3744 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
3748 compute_transp (x
, indx
, bmap
, set_p
)
3760 /* repeat is used to turn tail-recursion into iteration since GCC
3761 can't do it when there's no return value. */
3767 code
= GET_CODE (x
);
3773 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
3776 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
3777 SET_BIT (bmap
[bb
->index
], indx
);
3781 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
3782 SET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
3787 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
3790 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
3791 RESET_BIT (bmap
[bb
->index
], indx
);
3795 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
3796 RESET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
3805 rtx list_entry
= canon_modify_mem_list
[bb
->index
];
3809 rtx dest
, dest_addr
;
3811 if (GET_CODE (XEXP (list_entry
, 0)) == CALL_INSN
)
3814 SET_BIT (bmap
[bb
->index
], indx
);
3816 RESET_BIT (bmap
[bb
->index
], indx
);
3819 /* LIST_ENTRY must be an INSN of some kind that sets memory.
3820 Examine each hunk of memory that is modified. */
3822 dest
= XEXP (list_entry
, 0);
3823 list_entry
= XEXP (list_entry
, 1);
3824 dest_addr
= XEXP (list_entry
, 0);
3826 if (canon_true_dependence (dest
, GET_MODE (dest
), dest_addr
,
3827 x
, rtx_addr_varies_p
))
3830 SET_BIT (bmap
[bb
->index
], indx
);
3832 RESET_BIT (bmap
[bb
->index
], indx
);
3835 list_entry
= XEXP (list_entry
, 1);
3858 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3862 /* If we are about to do the last recursive call
3863 needed at this level, change it into iteration.
3864 This function is called enough to be worth it. */
3871 compute_transp (XEXP (x
, i
), indx
, bmap
, set_p
);
3873 else if (fmt
[i
] == 'E')
3874 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3875 compute_transp (XVECEXP (x
, i
, j
), indx
, bmap
, set_p
);
3879 /* Top level routine to do the dataflow analysis needed by copy/const
3883 compute_cprop_data ()
3885 compute_local_properties (cprop_absaltered
, cprop_pavloc
, NULL
, 1);
3886 compute_available (cprop_pavloc
, cprop_absaltered
,
3887 cprop_avout
, cprop_avin
);
3890 /* Copy/constant propagation. */
3892 /* Maximum number of register uses in an insn that we handle. */
3895 /* Table of uses found in an insn.
3896 Allocated statically to avoid alloc/free complexity and overhead. */
3897 static struct reg_use reg_use_table
[MAX_USES
];
3899 /* Index into `reg_use_table' while building it. */
3900 static int reg_use_count
;
3902 /* Set up a list of register numbers used in INSN. The found uses are stored
3903 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
3904 and contains the number of uses in the table upon exit.
3906 ??? If a register appears multiple times we will record it multiple times.
3907 This doesn't hurt anything but it will slow things down. */
3910 find_used_regs (xptr
, data
)
3912 void *data ATTRIBUTE_UNUSED
;
3919 /* repeat is used to turn tail-recursion into iteration since GCC
3920 can't do it when there's no return value. */
3925 code
= GET_CODE (x
);
3928 if (reg_use_count
== MAX_USES
)
3931 reg_use_table
[reg_use_count
].reg_rtx
= x
;
3935 /* Recursively scan the operands of this expression. */
3937 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3941 /* If we are about to do the last recursive call
3942 needed at this level, change it into iteration.
3943 This function is called enough to be worth it. */
3950 find_used_regs (&XEXP (x
, i
), data
);
3952 else if (fmt
[i
] == 'E')
3953 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3954 find_used_regs (&XVECEXP (x
, i
, j
), data
);
3958 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
3959 Returns non-zero is successful. */
3962 try_replace_reg (from
, to
, insn
)
3965 rtx note
= find_reg_equal_equiv_note (insn
);
3968 rtx set
= single_set (insn
);
3970 validate_replace_src_group (from
, to
, insn
);
3971 if (num_changes_pending () && apply_change_group ())
3974 if (!success
&& set
&& reg_mentioned_p (from
, SET_SRC (set
)))
3976 /* If above failed and this is a single set, try to simplify the source of
3977 the set given our substitution. We could perhaps try this for multiple
3978 SETs, but it probably won't buy us anything. */
3979 src
= simplify_replace_rtx (SET_SRC (set
), from
, to
);
3981 if (!rtx_equal_p (src
, SET_SRC (set
))
3982 && validate_change (insn
, &SET_SRC (set
), src
, 0))
3985 /* If we've failed to do replacement, have a single SET, and don't already
3986 have a note, add a REG_EQUAL note to not lose information. */
3987 if (!success
&& note
== 0 && set
!= 0)
3988 note
= set_unique_reg_note (insn
, REG_EQUAL
, copy_rtx (src
));
3991 /* If there is already a NOTE, update the expression in it with our
3994 XEXP (note
, 0) = simplify_replace_rtx (XEXP (note
, 0), from
, to
);
3996 /* REG_EQUAL may get simplified into register.
3997 We don't allow that. Remove that note. This code ought
3998 not to hapen, because previous code ought to syntetize
3999 reg-reg move, but be on the safe side. */
4000 if (note
&& REG_P (XEXP (note
, 0)))
4001 remove_note (insn
, note
);
4006 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
4007 NULL no such set is found. */
4009 static struct expr
*
4010 find_avail_set (regno
, insn
)
4014 /* SET1 contains the last set found that can be returned to the caller for
4015 use in a substitution. */
4016 struct expr
*set1
= 0;
4018 /* Loops are not possible here. To get a loop we would need two sets
4019 available at the start of the block containing INSN. ie we would
4020 need two sets like this available at the start of the block:
4022 (set (reg X) (reg Y))
4023 (set (reg Y) (reg X))
4025 This can not happen since the set of (reg Y) would have killed the
4026 set of (reg X) making it unavailable at the start of this block. */
4030 struct expr
*set
= lookup_set (regno
, NULL_RTX
);
4032 /* Find a set that is available at the start of the block
4033 which contains INSN. */
4036 if (TEST_BIT (cprop_avin
[BLOCK_NUM (insn
)], set
->bitmap_index
))
4038 set
= next_set (regno
, set
);
4041 /* If no available set was found we've reached the end of the
4042 (possibly empty) copy chain. */
4046 if (GET_CODE (set
->expr
) != SET
)
4049 src
= SET_SRC (set
->expr
);
4051 /* We know the set is available.
4052 Now check that SRC is ANTLOC (i.e. none of the source operands
4053 have changed since the start of the block).
4055 If the source operand changed, we may still use it for the next
4056 iteration of this loop, but we may not use it for substitutions. */
4058 if (CONSTANT_P (src
) || oprs_not_set_p (src
, insn
))
4061 /* If the source of the set is anything except a register, then
4062 we have reached the end of the copy chain. */
4063 if (GET_CODE (src
) != REG
)
4066 /* Follow the copy chain, ie start another iteration of the loop
4067 and see if we have an available copy into SRC. */
4068 regno
= REGNO (src
);
4071 /* SET1 holds the last set that was available and anticipatable at
4076 /* Subroutine of cprop_insn that tries to propagate constants into
4077 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
4078 it is the instruction that immediately preceeds JUMP, and must be a
4079 single SET of a register. FROM is what we will try to replace,
4080 SRC is the constant we will try to substitute for it. Returns nonzero
4081 if a change was made. */
4084 cprop_jump (bb
, setcc
, jump
, from
, src
)
4092 rtx set
= pc_set (jump
);
4094 /* First substitute in the INSN condition as the SET_SRC of the JUMP,
4095 then substitute that given values in this expanded JUMP. */
4098 rtx setcc_set
= single_set (setcc
);
4099 new_set
= simplify_replace_rtx (SET_SRC (set
),
4100 SET_DEST (setcc_set
),
4101 SET_SRC (setcc_set
));
4106 new = simplify_replace_rtx (new_set
, from
, src
);
4108 /* If no simplification can be made, then try the next
4110 if (rtx_equal_p (new, new_set
))
4113 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
4118 if (! validate_change (jump
, &SET_SRC (set
), new, 0))
4121 /* If this has turned into an unconditional jump,
4122 then put a barrier after it so that the unreachable
4123 code will be deleted. */
4124 if (GET_CODE (SET_SRC (set
)) == LABEL_REF
)
4125 emit_barrier_after (jump
);
4129 /* Delete the cc0 setter. */
4130 if (setcc
!= NULL
&& CC0_P (SET_DEST (single_set (setcc
))))
4131 delete_insn (setcc
);
4134 run_jump_opt_after_gcse
= 1;
4137 if (gcse_file
!= NULL
)
4140 "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
4141 REGNO (from
), INSN_UID (jump
));
4142 print_rtl (gcse_file
, src
);
4143 fprintf (gcse_file
, "\n");
4145 purge_dead_edges (bb
);
4151 constprop_register (insn
, from
, to
, alter_jumps
)
4159 /* Check for reg or cc0 setting instructions followed by
4160 conditional branch instructions first. */
4162 && (sset
= single_set (insn
)) != NULL
4163 && any_condjump_p (NEXT_INSN (insn
)) && onlyjump_p (NEXT_INSN (insn
)))
4165 rtx dest
= SET_DEST (sset
);
4166 if ((REG_P (dest
) || CC0_P (dest
))
4167 && cprop_jump (BLOCK_FOR_INSN (insn
), insn
, NEXT_INSN (insn
), from
, to
))
4171 /* Handle normal insns next. */
4172 if (GET_CODE (insn
) == INSN
4173 && try_replace_reg (from
, to
, insn
))
4176 /* Try to propagate a CONST_INT into a conditional jump.
4177 We're pretty specific about what we will handle in this
4178 code, we can extend this as necessary over time.
4180 Right now the insn in question must look like
4181 (set (pc) (if_then_else ...)) */
4182 else if (alter_jumps
&& any_condjump_p (insn
) && onlyjump_p (insn
))
4183 return cprop_jump (BLOCK_FOR_INSN (insn
), NULL
, insn
, from
, to
);
4187 /* Perform constant and copy propagation on INSN.
4188 The result is non-zero if a change was made. */
4191 cprop_insn (insn
, alter_jumps
)
4195 struct reg_use
*reg_used
;
4203 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4205 note
= find_reg_equal_equiv_note (insn
);
4207 /* We may win even when propagating constants into notes. */
4209 find_used_regs (&XEXP (note
, 0), NULL
);
4211 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
4212 reg_used
++, reg_use_count
--)
4214 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
4218 /* Ignore registers created by GCSE.
4219 We do this because ... */
4220 if (regno
>= max_gcse_regno
)
4223 /* If the register has already been set in this block, there's
4224 nothing we can do. */
4225 if (! oprs_not_set_p (reg_used
->reg_rtx
, insn
))
4228 /* Find an assignment that sets reg_used and is available
4229 at the start of the block. */
4230 set
= find_avail_set (regno
, insn
);
4235 /* ??? We might be able to handle PARALLELs. Later. */
4236 if (GET_CODE (pat
) != SET
)
4239 src
= SET_SRC (pat
);
4241 /* Constant propagation. */
4242 if (CONSTANT_P (src
))
4244 if (constprop_register (insn
, reg_used
->reg_rtx
, src
, alter_jumps
))
4248 if (gcse_file
!= NULL
)
4250 fprintf (gcse_file
, "GLOBAL CONST-PROP: Replacing reg %d in ", regno
);
4251 fprintf (gcse_file
, "insn %d with constant ", INSN_UID (insn
));
4252 print_rtl (gcse_file
, src
);
4253 fprintf (gcse_file
, "\n");
4257 else if (GET_CODE (src
) == REG
4258 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
4259 && REGNO (src
) != regno
)
4261 if (try_replace_reg (reg_used
->reg_rtx
, src
, insn
))
4265 if (gcse_file
!= NULL
)
4267 fprintf (gcse_file
, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
4268 regno
, INSN_UID (insn
));
4269 fprintf (gcse_file
, " with reg %d\n", REGNO (src
));
4272 /* The original insn setting reg_used may or may not now be
4273 deletable. We leave the deletion to flow. */
4274 /* FIXME: If it turns out that the insn isn't deletable,
4275 then we may have unnecessarily extended register lifetimes
4276 and made things worse. */
4285 do_local_cprop (x
, insn
, alter_jumps
)
4290 rtx newreg
= NULL
, newcnst
= NULL
;
4292 /* Rule out USE instructions and ASM statements as we don't want to change the hard
4293 registers mentioned. */
4294 if (GET_CODE (x
) == REG
4295 && (REGNO (x
) >= FIRST_PSEUDO_REGISTER
4296 || (GET_CODE (PATTERN (insn
)) != USE
&& asm_noperands (PATTERN (insn
)) < 0)))
4298 cselib_val
*val
= cselib_lookup (x
, GET_MODE (x
), 0);
4299 struct elt_loc_list
*l
;
4303 for (l
= val
->locs
; l
; l
= l
->next
)
4305 rtx this_rtx
= l
->loc
;
4308 if (CONSTANT_P (this_rtx
))
4310 if (REG_P (this_rtx
) && REGNO (this_rtx
) >= FIRST_PSEUDO_REGISTER
4311 /* Don't copy propagate if it has attached REG_EQUIV note.
4312 At this point this only function parameters should have
4313 REG_EQUIV notes and if the argument slot is used somewhere
4314 explicitly, it means address of parameter has been taken,
4315 so we should not extend the lifetime of the pseudo. */
4316 && (!(note
= find_reg_note (l
->setting_insn
, REG_EQUIV
, NULL_RTX
))
4317 || GET_CODE (XEXP (note
, 0)) != MEM
))
4320 if (newcnst
&& constprop_register (insn
, x
, newcnst
, alter_jumps
))
4322 if (gcse_file
!= NULL
)
4324 fprintf (gcse_file
, "LOCAL CONST-PROP: Replacing reg %d in ",
4326 fprintf (gcse_file
, "insn %d with constant ",
4328 print_rtl (gcse_file
, newcnst
);
4329 fprintf (gcse_file
, "\n");
4334 else if (newreg
&& newreg
!= x
&& try_replace_reg (x
, newreg
, insn
))
4336 if (gcse_file
!= NULL
)
4339 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
4340 REGNO (x
), INSN_UID (insn
));
4341 fprintf (gcse_file
, " with reg %d\n", REGNO (newreg
));
4351 local_cprop_pass (alter_jumps
)
4355 struct reg_use
*reg_used
;
4358 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4362 rtx note
= find_reg_equal_equiv_note (insn
);
4367 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4369 find_used_regs (&XEXP (note
, 0), NULL
);
4371 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
4372 reg_used
++, reg_use_count
--)
4373 if (do_local_cprop (reg_used
->reg_rtx
, insn
, alter_jumps
))
4376 while (reg_use_count
);
4378 cselib_process_insn (insn
);
4383 /* Forward propagate copies. This includes copies and constants. Return
4384 non-zero if a change was made. */
4394 /* Note we start at block 1. */
4395 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
4397 if (gcse_file
!= NULL
)
4398 fprintf (gcse_file
, "\n");
4403 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
4405 /* Reset tables used to keep track of what's still valid [since the
4406 start of the block]. */
4407 reset_opr_set_tables ();
4409 for (insn
= bb
->head
;
4410 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
4411 insn
= NEXT_INSN (insn
))
4414 changed
|= cprop_insn (insn
, alter_jumps
);
4416 /* Keep track of everything modified by this insn. */
4417 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
4418 call mark_oprs_set if we turned the insn into a NOTE. */
4419 if (GET_CODE (insn
) != NOTE
)
4420 mark_oprs_set (insn
);
4424 if (gcse_file
!= NULL
)
4425 fprintf (gcse_file
, "\n");
4430 /* Perform one copy/constant propagation pass.
4431 F is the first insn in the function.
4432 PASS is the pass count. */
4435 one_cprop_pass (pass
, alter_jumps
)
4441 const_prop_count
= 0;
4442 copy_prop_count
= 0;
4444 local_cprop_pass (alter_jumps
);
4446 alloc_set_hash_table (max_cuid
);
4447 compute_set_hash_table ();
4449 dump_hash_table (gcse_file
, "SET", set_hash_table
, set_hash_table_size
,
4453 alloc_cprop_mem (last_basic_block
, n_sets
);
4454 compute_cprop_data ();
4455 changed
= cprop (alter_jumps
);
4457 changed
|= bypass_conditional_jumps ();
4461 free_set_hash_table ();
4465 fprintf (gcse_file
, "CPROP of %s, pass %d: %d bytes needed, ",
4466 current_function_name
, pass
, bytes_used
);
4467 fprintf (gcse_file
, "%d const props, %d copy props\n\n",
4468 const_prop_count
, copy_prop_count
);
4474 /* Bypass conditional jumps. */
4476 /* Find a set of REGNO to a constant that is available at the end of basic
4477 block BB. Returns NULL if no such set is found. Based heavily upon
4480 static struct expr
*
4481 find_bypass_set (regno
, bb
)
4485 struct expr
*result
= 0;
4490 struct expr
*set
= lookup_set (regno
, NULL_RTX
);
4494 if (TEST_BIT (cprop_avout
[bb
], set
->bitmap_index
))
4496 set
= next_set (regno
, set
);
4502 if (GET_CODE (set
->expr
) != SET
)
4505 src
= SET_SRC (set
->expr
);
4506 if (CONSTANT_P (src
))
4509 if (GET_CODE (src
) != REG
)
4512 regno
= REGNO (src
);
4518 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
4519 basic block BB which has more than one predecessor. If not NULL, SETCC
4520 is the first instruction of BB, which is immediately followed by JUMP_INSN
4521 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
4522 Returns nonzero if a change was made. */
4525 bypass_block (bb
, setcc
, jump
)
4533 insn
= (setcc
!= NULL
) ? setcc
: jump
;
4535 /* Determine set of register uses in INSN. */
4537 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4538 note
= find_reg_equal_equiv_note (insn
);
4540 find_used_regs (&XEXP (note
, 0), NULL
);
4543 for (e
= bb
->pred
; e
; e
= enext
)
4545 enext
= e
->pred_next
;
4546 for (i
= 0; i
< reg_use_count
; i
++)
4548 struct reg_use
*reg_used
= ®_use_table
[i
];
4549 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
4550 basic_block dest
, old_dest
;
4554 if (regno
>= max_gcse_regno
)
4557 set
= find_bypass_set (regno
, e
->src
->index
);
4562 src
= SET_SRC (pc_set (jump
));
4565 src
= simplify_replace_rtx (src
,
4566 SET_DEST (PATTERN (setcc
)),
4567 SET_SRC (PATTERN (setcc
)));
4569 new = simplify_replace_rtx (src
, reg_used
->reg_rtx
,
4570 SET_SRC (set
->expr
));
4573 dest
= FALLTHRU_EDGE (bb
)->dest
;
4574 else if (GET_CODE (new) == LABEL_REF
)
4575 dest
= BRANCH_EDGE (bb
)->dest
;
4579 /* Once basic block indices are stable, we should be able
4580 to use redirect_edge_and_branch_force instead. */
4582 if (dest
!= NULL
&& dest
!= old_dest
4583 && redirect_edge_and_branch (e
, dest
))
4585 /* Copy the register setter to the redirected edge.
4586 Don't copy CC0 setters, as CC0 is dead after jump. */
4589 rtx pat
= PATTERN (setcc
);
4590 if (!CC0_P (SET_DEST (pat
)))
4591 insert_insn_on_edge (copy_insn (pat
), e
);
4594 if (gcse_file
!= NULL
)
4596 fprintf (gcse_file
, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
4597 regno
, INSN_UID (jump
));
4598 print_rtl (gcse_file
, SET_SRC (set
->expr
));
4599 fprintf (gcse_file
, "\nBypass edge from %d->%d to %d\n",
4600 e
->src
->index
, old_dest
->index
, dest
->index
);
4610 /* Find basic blocks with more than one predecessor that only contain a
4611 single conditional jump. If the result of the comparison is known at
4612 compile-time from any incoming edge, redirect that edge to the
4613 appropriate target. Returns nonzero if a change was made. */
4616 bypass_conditional_jumps ()
4624 /* Note we start at block 1. */
4625 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
4629 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
,
4630 EXIT_BLOCK_PTR
, next_bb
)
4632 /* Check for more than one predecessor. */
4633 if (bb
->pred
&& bb
->pred
->pred_next
)
4636 for (insn
= bb
->head
;
4637 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
4638 insn
= NEXT_INSN (insn
))
4639 if (GET_CODE (insn
) == INSN
)
4643 if (GET_CODE (PATTERN (insn
)) != SET
)
4646 dest
= SET_DEST (PATTERN (insn
));
4647 if (REG_P (dest
) || CC0_P (dest
))
4652 else if (GET_CODE (insn
) == JUMP_INSN
)
4654 if (any_condjump_p (insn
) && onlyjump_p (insn
))
4655 changed
|= bypass_block (bb
, setcc
, insn
);
4658 else if (INSN_P (insn
))
4663 /* If we bypassed any register setting insns, we inserted a
4664 copy on the redirected edge. These need to be commited. */
4666 commit_edge_insertions();
4671 /* Compute PRE+LCM working variables. */
4673 /* Local properties of expressions. */
4674 /* Nonzero for expressions that are transparent in the block. */
4675 static sbitmap
*transp
;
4677 /* Nonzero for expressions that are transparent at the end of the block.
4678 This is only zero for expressions killed by abnormal critical edge
4679 created by a calls. */
4680 static sbitmap
*transpout
;
4682 /* Nonzero for expressions that are computed (available) in the block. */
4683 static sbitmap
*comp
;
4685 /* Nonzero for expressions that are locally anticipatable in the block. */
4686 static sbitmap
*antloc
;
4688 /* Nonzero for expressions where this block is an optimal computation
4690 static sbitmap
*pre_optimal
;
4692 /* Nonzero for expressions which are redundant in a particular block. */
4693 static sbitmap
*pre_redundant
;
4695 /* Nonzero for expressions which should be inserted on a specific edge. */
4696 static sbitmap
*pre_insert_map
;
4698 /* Nonzero for expressions which should be deleted in a specific block. */
4699 static sbitmap
*pre_delete_map
;
4701 /* Contains the edge_list returned by pre_edge_lcm. */
4702 static struct edge_list
*edge_list
;
4704 /* Redundant insns. */
4705 static sbitmap pre_redundant_insns
;
4707 /* Allocate vars used for PRE analysis. */
4710 alloc_pre_mem (n_blocks
, n_exprs
)
4711 int n_blocks
, n_exprs
;
4713 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4714 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4715 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4718 pre_redundant
= NULL
;
4719 pre_insert_map
= NULL
;
4720 pre_delete_map
= NULL
;
4723 ae_kill
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4725 /* pre_insert and pre_delete are allocated later. */
4728 /* Free vars used for PRE analysis. */
4733 sbitmap_vector_free (transp
);
4734 sbitmap_vector_free (comp
);
4736 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
4739 sbitmap_vector_free (pre_optimal
);
4741 sbitmap_vector_free (pre_redundant
);
4743 sbitmap_vector_free (pre_insert_map
);
4745 sbitmap_vector_free (pre_delete_map
);
4747 sbitmap_vector_free (ae_in
);
4749 sbitmap_vector_free (ae_out
);
4751 transp
= comp
= NULL
;
4752 pre_optimal
= pre_redundant
= pre_insert_map
= pre_delete_map
= NULL
;
4753 ae_in
= ae_out
= NULL
;
4756 /* Top level routine to do the dataflow analysis needed by PRE. */
4761 sbitmap trapping_expr
;
4765 compute_local_properties (transp
, comp
, antloc
, 0);
4766 sbitmap_vector_zero (ae_kill
, last_basic_block
);
4768 /* Collect expressions which might trap. */
4769 trapping_expr
= sbitmap_alloc (n_exprs
);
4770 sbitmap_zero (trapping_expr
);
4771 for (ui
= 0; ui
< expr_hash_table_size
; ui
++)
4774 for (e
= expr_hash_table
[ui
]; e
!= NULL
; e
= e
->next_same_hash
)
4775 if (may_trap_p (e
->expr
))
4776 SET_BIT (trapping_expr
, e
->bitmap_index
);
4779 /* Compute ae_kill for each basic block using:
4783 This is significantly faster than compute_ae_kill. */
4789 /* If the current block is the destination of an abnormal edge, we
4790 kill all trapping expressions because we won't be able to properly
4791 place the instruction on the edge. So make them neither
4792 anticipatable nor transparent. This is fairly conservative. */
4793 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
4794 if (e
->flags
& EDGE_ABNORMAL
)
4796 sbitmap_difference (antloc
[bb
->index
], antloc
[bb
->index
], trapping_expr
);
4797 sbitmap_difference (transp
[bb
->index
], transp
[bb
->index
], trapping_expr
);
4801 sbitmap_a_or_b (ae_kill
[bb
->index
], transp
[bb
->index
], comp
[bb
->index
]);
4802 sbitmap_not (ae_kill
[bb
->index
], ae_kill
[bb
->index
]);
4805 edge_list
= pre_edge_lcm (gcse_file
, n_exprs
, transp
, comp
, antloc
,
4806 ae_kill
, &pre_insert_map
, &pre_delete_map
);
4807 sbitmap_vector_free (antloc
);
4809 sbitmap_vector_free (ae_kill
);
4811 sbitmap_free (trapping_expr
);
4816 /* Return non-zero if an occurrence of expression EXPR in OCCR_BB would reach
4819 VISITED is a pointer to a working buffer for tracking which BB's have
4820 been visited. It is NULL for the top-level call.
4822 We treat reaching expressions that go through blocks containing the same
4823 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
4824 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
4825 2 as not reaching. The intent is to improve the probability of finding
4826 only one reaching expression and to reduce register lifetimes by picking
4827 the closest such expression. */
4830 pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
)
4831 basic_block occr_bb
;
4838 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
4840 basic_block pred_bb
= pred
->src
;
4842 if (pred
->src
== ENTRY_BLOCK_PTR
4843 /* Has predecessor has already been visited? */
4844 || visited
[pred_bb
->index
])
4845 ;/* Nothing to do. */
4847 /* Does this predecessor generate this expression? */
4848 else if (TEST_BIT (comp
[pred_bb
->index
], expr
->bitmap_index
))
4850 /* Is this the occurrence we're looking for?
4851 Note that there's only one generating occurrence per block
4852 so we just need to check the block number. */
4853 if (occr_bb
== pred_bb
)
4856 visited
[pred_bb
->index
] = 1;
4858 /* Ignore this predecessor if it kills the expression. */
4859 else if (! TEST_BIT (transp
[pred_bb
->index
], expr
->bitmap_index
))
4860 visited
[pred_bb
->index
] = 1;
4862 /* Neither gen nor kill. */
4865 visited
[pred_bb
->index
] = 1;
4866 if (pre_expr_reaches_here_p_work (occr_bb
, expr
, pred_bb
, visited
))
4871 /* All paths have been checked. */
4875 /* The wrapper for pre_expr_reaches_here_work that ensures that any
4876 memory allocated for that function is returned. */
4879 pre_expr_reaches_here_p (occr_bb
, expr
, bb
)
4880 basic_block occr_bb
;
4885 char *visited
= (char *) xcalloc (last_basic_block
, 1);
4887 rval
= pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
);
4894 /* Given an expr, generate RTL which we can insert at the end of a BB,
4895 or on an edge. Set the block number of any insns generated to
4899 process_insert_insn (expr
)
4902 rtx reg
= expr
->reaching_reg
;
4903 rtx exp
= copy_rtx (expr
->expr
);
4908 /* If the expression is something that's an operand, like a constant,
4909 just copy it to a register. */
4910 if (general_operand (exp
, GET_MODE (reg
)))
4911 emit_move_insn (reg
, exp
);
4913 /* Otherwise, make a new insn to compute this expression and make sure the
4914 insn will be recognized (this also adds any needed CLOBBERs). Copy the
4915 expression to make sure we don't have any sharing issues. */
4916 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode
, reg
, exp
))))
4925 /* Add EXPR to the end of basic block BB.
4927 This is used by both the PRE and code hoisting.
4929 For PRE, we want to verify that the expr is either transparent
4930 or locally anticipatable in the target block. This check makes
4931 no sense for code hoisting. */
4934 insert_insn_end_bb (expr
, bb
, pre
)
4941 rtx reg
= expr
->reaching_reg
;
4942 int regno
= REGNO (reg
);
4945 pat
= process_insert_insn (expr
);
4946 if (pat
== NULL_RTX
|| ! INSN_P (pat
))
4950 while (NEXT_INSN (pat_end
) != NULL_RTX
)
4951 pat_end
= NEXT_INSN (pat_end
);
4953 /* If the last insn is a jump, insert EXPR in front [taking care to
4954 handle cc0, etc. properly]. Similary we need to care trapping
4955 instructions in presence of non-call exceptions. */
4957 if (GET_CODE (insn
) == JUMP_INSN
4958 || (GET_CODE (insn
) == INSN
4959 && (bb
->succ
->succ_next
|| (bb
->succ
->flags
& EDGE_ABNORMAL
))))
4964 /* It should always be the case that we can put these instructions
4965 anywhere in the basic block with performing PRE optimizations.
4967 if (GET_CODE (insn
) == INSN
&& pre
4968 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
4969 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
4972 /* If this is a jump table, then we can't insert stuff here. Since
4973 we know the previous real insn must be the tablejump, we insert
4974 the new instruction just before the tablejump. */
4975 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
4976 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
4977 insn
= prev_real_insn (insn
);
4980 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4981 if cc0 isn't set. */
4982 note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
4984 insn
= XEXP (note
, 0);
4987 rtx maybe_cc0_setter
= prev_nonnote_insn (insn
);
4988 if (maybe_cc0_setter
4989 && INSN_P (maybe_cc0_setter
)
4990 && sets_cc0_p (PATTERN (maybe_cc0_setter
)))
4991 insn
= maybe_cc0_setter
;
4994 /* FIXME: What if something in cc0/jump uses value set in new insn? */
4995 new_insn
= emit_insn_before (pat
, insn
);
4998 /* Likewise if the last insn is a call, as will happen in the presence
4999 of exception handling. */
5000 else if (GET_CODE (insn
) == CALL_INSN
5001 && (bb
->succ
->succ_next
|| (bb
->succ
->flags
& EDGE_ABNORMAL
)))
5003 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
5004 we search backward and place the instructions before the first
5005 parameter is loaded. Do this for everyone for consistency and a
5006 presumtion that we'll get better code elsewhere as well.
5008 It should always be the case that we can put these instructions
5009 anywhere in the basic block with performing PRE optimizations.
5013 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
5014 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
5017 /* Since different machines initialize their parameter registers
5018 in different orders, assume nothing. Collect the set of all
5019 parameter registers. */
5020 insn
= find_first_parameter_load (insn
, bb
->head
);
5022 /* If we found all the parameter loads, then we want to insert
5023 before the first parameter load.
5025 If we did not find all the parameter loads, then we might have
5026 stopped on the head of the block, which could be a CODE_LABEL.
5027 If we inserted before the CODE_LABEL, then we would be putting
5028 the insn in the wrong basic block. In that case, put the insn
5029 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
5030 while (GET_CODE (insn
) == CODE_LABEL
5031 || NOTE_INSN_BASIC_BLOCK_P (insn
))
5032 insn
= NEXT_INSN (insn
);
5034 new_insn
= emit_insn_before (pat
, insn
);
5037 new_insn
= emit_insn_after (pat
, insn
);
5043 add_label_notes (PATTERN (pat
), new_insn
);
5044 note_stores (PATTERN (pat
), record_set_info
, pat
);
5048 pat
= NEXT_INSN (pat
);
5051 gcse_create_count
++;
5055 fprintf (gcse_file
, "PRE/HOIST: end of bb %d, insn %d, ",
5056 bb
->index
, INSN_UID (new_insn
));
5057 fprintf (gcse_file
, "copying expression %d to reg %d\n",
5058 expr
->bitmap_index
, regno
);
5062 /* Insert partially redundant expressions on edges in the CFG to make
5063 the expressions fully redundant. */
5066 pre_edge_insert (edge_list
, index_map
)
5067 struct edge_list
*edge_list
;
5068 struct expr
**index_map
;
5070 int e
, i
, j
, num_edges
, set_size
, did_insert
= 0;
5073 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
5074 if it reaches any of the deleted expressions. */
5076 set_size
= pre_insert_map
[0]->size
;
5077 num_edges
= NUM_EDGES (edge_list
);
5078 inserted
= sbitmap_vector_alloc (num_edges
, n_exprs
);
5079 sbitmap_vector_zero (inserted
, num_edges
);
5081 for (e
= 0; e
< num_edges
; e
++)
5084 basic_block bb
= INDEX_EDGE_PRED_BB (edge_list
, e
);
5086 for (i
= indx
= 0; i
< set_size
; i
++, indx
+= SBITMAP_ELT_BITS
)
5088 SBITMAP_ELT_TYPE insert
= pre_insert_map
[e
]->elms
[i
];
5090 for (j
= indx
; insert
&& j
< n_exprs
; j
++, insert
>>= 1)
5091 if ((insert
& 1) != 0 && index_map
[j
]->reaching_reg
!= NULL_RTX
)
5093 struct expr
*expr
= index_map
[j
];
5096 /* Now look at each deleted occurrence of this expression. */
5097 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5099 if (! occr
->deleted_p
)
5102 /* Insert this expression on this edge if if it would
5103 reach the deleted occurrence in BB. */
5104 if (!TEST_BIT (inserted
[e
], j
))
5107 edge eg
= INDEX_EDGE (edge_list
, e
);
5109 /* We can't insert anything on an abnormal and
5110 critical edge, so we insert the insn at the end of
5111 the previous block. There are several alternatives
5112 detailed in Morgans book P277 (sec 10.5) for
5113 handling this situation. This one is easiest for
5116 if ((eg
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
5117 insert_insn_end_bb (index_map
[j
], bb
, 0);
5120 insn
= process_insert_insn (index_map
[j
]);
5121 insert_insn_on_edge (insn
, eg
);
5126 fprintf (gcse_file
, "PRE/HOIST: edge (%d,%d), ",
5128 INDEX_EDGE_SUCC_BB (edge_list
, e
)->index
);
5129 fprintf (gcse_file
, "copy expression %d\n",
5130 expr
->bitmap_index
);
5133 update_ld_motion_stores (expr
);
5134 SET_BIT (inserted
[e
], j
);
5136 gcse_create_count
++;
5143 sbitmap_vector_free (inserted
);
5147 /* Copy the result of INSN to REG. INDX is the expression number. */
5150 pre_insert_copy_insn (expr
, insn
)
5154 rtx reg
= expr
->reaching_reg
;
5155 int regno
= REGNO (reg
);
5156 int indx
= expr
->bitmap_index
;
5157 rtx set
= single_set (insn
);
5163 new_insn
= emit_insn_after (gen_move_insn (reg
, SET_DEST (set
)), insn
);
5165 /* Keep register set table up to date. */
5166 record_one_set (regno
, new_insn
);
5168 gcse_create_count
++;
5172 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
5173 BLOCK_NUM (insn
), INSN_UID (new_insn
), indx
,
5174 INSN_UID (insn
), regno
);
5175 update_ld_motion_stores (expr
);
5178 /* Copy available expressions that reach the redundant expression
5179 to `reaching_reg'. */
5182 pre_insert_copies ()
5189 /* For each available expression in the table, copy the result to
5190 `reaching_reg' if the expression reaches a deleted one.
5192 ??? The current algorithm is rather brute force.
5193 Need to do some profiling. */
5195 for (i
= 0; i
< expr_hash_table_size
; i
++)
5196 for (expr
= expr_hash_table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5198 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
5199 we don't want to insert a copy here because the expression may not
5200 really be redundant. So only insert an insn if the expression was
5201 deleted. This test also avoids further processing if the
5202 expression wasn't deleted anywhere. */
5203 if (expr
->reaching_reg
== NULL
)
5206 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5208 if (! occr
->deleted_p
)
5211 for (avail
= expr
->avail_occr
; avail
!= NULL
; avail
= avail
->next
)
5213 rtx insn
= avail
->insn
;
5215 /* No need to handle this one if handled already. */
5216 if (avail
->copied_p
)
5219 /* Don't handle this one if it's a redundant one. */
5220 if (TEST_BIT (pre_redundant_insns
, INSN_CUID (insn
)))
5223 /* Or if the expression doesn't reach the deleted one. */
5224 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail
->insn
),
5226 BLOCK_FOR_INSN (occr
->insn
)))
5229 /* Copy the result of avail to reaching_reg. */
5230 pre_insert_copy_insn (expr
, insn
);
5231 avail
->copied_p
= 1;
5237 /* Emit move from SRC to DEST noting the equivalence with expression computed
5240 gcse_emit_move_after (src
, dest
, insn
)
5241 rtx src
, dest
, insn
;
5244 rtx set
= single_set (insn
), set2
;
5248 /* This should never fail since we're creating a reg->reg copy
5249 we've verified to be valid. */
5251 new = emit_insn_after (gen_move_insn (dest
, src
), insn
);
5253 /* Note the equivalence for local CSE pass. */
5254 set2
= single_set (new);
5255 if (!set2
|| !rtx_equal_p (SET_DEST (set2
), dest
))
5257 if ((note
= find_reg_equal_equiv_note (insn
)))
5258 eqv
= XEXP (note
, 0);
5260 eqv
= SET_SRC (set
);
5262 set_unique_reg_note (new, REG_EQUAL
, copy_insn_1 (src
));
5267 /* Delete redundant computations.
5268 Deletion is done by changing the insn to copy the `reaching_reg' of
5269 the expression into the result of the SET. It is left to later passes
5270 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
5272 Returns non-zero if a change is made. */
5283 for (i
= 0; i
< expr_hash_table_size
; i
++)
5284 for (expr
= expr_hash_table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5286 int indx
= expr
->bitmap_index
;
5288 /* We only need to search antic_occr since we require
5291 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5293 rtx insn
= occr
->insn
;
5295 basic_block bb
= BLOCK_FOR_INSN (insn
);
5297 if (TEST_BIT (pre_delete_map
[bb
->index
], indx
))
5299 set
= single_set (insn
);
5303 /* Create a pseudo-reg to store the result of reaching
5304 expressions into. Get the mode for the new pseudo from
5305 the mode of the original destination pseudo. */
5306 if (expr
->reaching_reg
== NULL
)
5308 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
5310 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
5312 occr
->deleted_p
= 1;
5313 SET_BIT (pre_redundant_insns
, INSN_CUID (insn
));
5320 "PRE: redundant insn %d (expression %d) in ",
5321 INSN_UID (insn
), indx
);
5322 fprintf (gcse_file
, "bb %d, reaching reg is %d\n",
5323 bb
->index
, REGNO (expr
->reaching_reg
));
5332 /* Perform GCSE optimizations using PRE.
5333 This is called by one_pre_gcse_pass after all the dataflow analysis
5336 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
5337 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
5338 Compiler Design and Implementation.
5340 ??? A new pseudo reg is created to hold the reaching expression. The nice
5341 thing about the classical approach is that it would try to use an existing
5342 reg. If the register can't be adequately optimized [i.e. we introduce
5343 reload problems], one could add a pass here to propagate the new register
5346 ??? We don't handle single sets in PARALLELs because we're [currently] not
5347 able to copy the rest of the parallel when we insert copies to create full
5348 redundancies from partial redundancies. However, there's no reason why we
5349 can't handle PARALLELs in the cases where there are no partial
5356 int did_insert
, changed
;
5357 struct expr
**index_map
;
5360 /* Compute a mapping from expression number (`bitmap_index') to
5361 hash table entry. */
5363 index_map
= (struct expr
**) xcalloc (n_exprs
, sizeof (struct expr
*));
5364 for (i
= 0; i
< expr_hash_table_size
; i
++)
5365 for (expr
= expr_hash_table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5366 index_map
[expr
->bitmap_index
] = expr
;
5368 /* Reset bitmap used to track which insns are redundant. */
5369 pre_redundant_insns
= sbitmap_alloc (max_cuid
);
5370 sbitmap_zero (pre_redundant_insns
);
5372 /* Delete the redundant insns first so that
5373 - we know what register to use for the new insns and for the other
5374 ones with reaching expressions
5375 - we know which insns are redundant when we go to create copies */
5377 changed
= pre_delete ();
5379 did_insert
= pre_edge_insert (edge_list
, index_map
);
5381 /* In other places with reaching expressions, copy the expression to the
5382 specially allocated pseudo-reg that reaches the redundant expr. */
5383 pre_insert_copies ();
5386 commit_edge_insertions ();
5391 sbitmap_free (pre_redundant_insns
);
5395 /* Top level routine to perform one PRE GCSE pass.
5397 Return non-zero if a change was made. */
5400 one_pre_gcse_pass (pass
)
5405 gcse_subst_count
= 0;
5406 gcse_create_count
= 0;
5408 alloc_expr_hash_table (max_cuid
);
5409 add_noreturn_fake_exit_edges ();
5411 compute_ld_motion_mems ();
5413 compute_expr_hash_table ();
5414 trim_ld_motion_mems ();
5416 dump_hash_table (gcse_file
, "Expression", expr_hash_table
,
5417 expr_hash_table_size
, n_exprs
);
5421 alloc_pre_mem (last_basic_block
, n_exprs
);
5422 compute_pre_data ();
5423 changed
|= pre_gcse ();
5424 free_edge_list (edge_list
);
5429 remove_fake_edges ();
5430 free_expr_hash_table ();
5434 fprintf (gcse_file
, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
5435 current_function_name
, pass
, bytes_used
);
5436 fprintf (gcse_file
, "%d substs, %d insns created\n",
5437 gcse_subst_count
, gcse_create_count
);
5443 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
5444 If notes are added to an insn which references a CODE_LABEL, the
5445 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
5446 because the following loop optimization pass requires them. */
5448 /* ??? This is very similar to the loop.c add_label_notes function. We
5449 could probably share code here. */
5451 /* ??? If there was a jump optimization pass after gcse and before loop,
5452 then we would not need to do this here, because jump would add the
5453 necessary REG_LABEL notes. */
5456 add_label_notes (x
, insn
)
5460 enum rtx_code code
= GET_CODE (x
);
5464 if (code
== LABEL_REF
&& !LABEL_REF_NONLOCAL_P (x
))
5466 /* This code used to ignore labels that referred to dispatch tables to
5467 avoid flow generating (slighly) worse code.
5469 We no longer ignore such label references (see LABEL_REF handling in
5470 mark_jump_label for additional information). */
5472 REG_NOTES (insn
) = gen_rtx_INSN_LIST (REG_LABEL
, XEXP (x
, 0),
5474 if (LABEL_P (XEXP (x
, 0)))
5475 LABEL_NUSES (XEXP (x
, 0))++;
5479 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
5482 add_label_notes (XEXP (x
, i
), insn
);
5483 else if (fmt
[i
] == 'E')
5484 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5485 add_label_notes (XVECEXP (x
, i
, j
), insn
);
5489 /* Compute transparent outgoing information for each block.
5491 An expression is transparent to an edge unless it is killed by
5492 the edge itself. This can only happen with abnormal control flow,
5493 when the edge is traversed through a call. This happens with
5494 non-local labels and exceptions.
5496 This would not be necessary if we split the edge. While this is
5497 normally impossible for abnormal critical edges, with some effort
5498 it should be possible with exception handling, since we still have
5499 control over which handler should be invoked. But due to increased
5500 EH table sizes, this may not be worthwhile. */
5503 compute_transpout ()
5509 sbitmap_vector_ones (transpout
, last_basic_block
);
5513 /* Note that flow inserted a nop a the end of basic blocks that
5514 end in call instructions for reasons other than abnormal
5516 if (GET_CODE (bb
->end
) != CALL_INSN
)
5519 for (i
= 0; i
< expr_hash_table_size
; i
++)
5520 for (expr
= expr_hash_table
[i
]; expr
; expr
= expr
->next_same_hash
)
5521 if (GET_CODE (expr
->expr
) == MEM
)
5523 if (GET_CODE (XEXP (expr
->expr
, 0)) == SYMBOL_REF
5524 && CONSTANT_POOL_ADDRESS_P (XEXP (expr
->expr
, 0)))
5527 /* ??? Optimally, we would use interprocedural alias
5528 analysis to determine if this mem is actually killed
5530 RESET_BIT (transpout
[bb
->index
], expr
->bitmap_index
);
5535 /* Removal of useless null pointer checks */
5537 /* Called via note_stores. X is set by SETTER. If X is a register we must
5538 invalidate nonnull_local and set nonnull_killed. DATA is really a
5539 `null_pointer_info *'.
5541 We ignore hard registers. */
5544 invalidate_nonnull_info (x
, setter
, data
)
5546 rtx setter ATTRIBUTE_UNUSED
;
5550 struct null_pointer_info
*npi
= (struct null_pointer_info
*) data
;
5552 while (GET_CODE (x
) == SUBREG
)
5555 /* Ignore anything that is not a register or is a hard register. */
5556 if (GET_CODE (x
) != REG
5557 || REGNO (x
) < npi
->min_reg
5558 || REGNO (x
) >= npi
->max_reg
)
5561 regno
= REGNO (x
) - npi
->min_reg
;
5563 RESET_BIT (npi
->nonnull_local
[npi
->current_block
->index
], regno
);
5564 SET_BIT (npi
->nonnull_killed
[npi
->current_block
->index
], regno
);
5567 /* Do null-pointer check elimination for the registers indicated in
5568 NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
5569 they are not our responsibility to free. */
5572 delete_null_pointer_checks_1 (block_reg
, nonnull_avin
,
5574 unsigned int *block_reg
;
5575 sbitmap
*nonnull_avin
;
5576 sbitmap
*nonnull_avout
;
5577 struct null_pointer_info
*npi
;
5579 basic_block bb
, current_block
;
5580 sbitmap
*nonnull_local
= npi
->nonnull_local
;
5581 sbitmap
*nonnull_killed
= npi
->nonnull_killed
;
5582 int something_changed
= 0;
5584 /* Compute local properties, nonnull and killed. A register will have
5585 the nonnull property if at the end of the current block its value is
5586 known to be nonnull. The killed property indicates that somewhere in
5587 the block any information we had about the register is killed.
5589 Note that a register can have both properties in a single block. That
5590 indicates that it's killed, then later in the block a new value is
5592 sbitmap_vector_zero (nonnull_local
, last_basic_block
);
5593 sbitmap_vector_zero (nonnull_killed
, last_basic_block
);
5595 FOR_EACH_BB (current_block
)
5597 rtx insn
, stop_insn
;
5599 /* Set the current block for invalidate_nonnull_info. */
5600 npi
->current_block
= current_block
;
5602 /* Scan each insn in the basic block looking for memory references and
5604 stop_insn
= NEXT_INSN (current_block
->end
);
5605 for (insn
= current_block
->head
;
5607 insn
= NEXT_INSN (insn
))
5612 /* Ignore anything that is not a normal insn. */
5613 if (! INSN_P (insn
))
5616 /* Basically ignore anything that is not a simple SET. We do have
5617 to make sure to invalidate nonnull_local and set nonnull_killed
5618 for such insns though. */
5619 set
= single_set (insn
);
5622 note_stores (PATTERN (insn
), invalidate_nonnull_info
, npi
);
5626 /* See if we've got a usable memory load. We handle it first
5627 in case it uses its address register as a dest (which kills
5628 the nonnull property). */
5629 if (GET_CODE (SET_SRC (set
)) == MEM
5630 && GET_CODE ((reg
= XEXP (SET_SRC (set
), 0))) == REG
5631 && REGNO (reg
) >= npi
->min_reg
5632 && REGNO (reg
) < npi
->max_reg
)
5633 SET_BIT (nonnull_local
[current_block
->index
],
5634 REGNO (reg
) - npi
->min_reg
);
5636 /* Now invalidate stuff clobbered by this insn. */
5637 note_stores (PATTERN (insn
), invalidate_nonnull_info
, npi
);
5639 /* And handle stores, we do these last since any sets in INSN can
5640 not kill the nonnull property if it is derived from a MEM
5641 appearing in a SET_DEST. */
5642 if (GET_CODE (SET_DEST (set
)) == MEM
5643 && GET_CODE ((reg
= XEXP (SET_DEST (set
), 0))) == REG
5644 && REGNO (reg
) >= npi
->min_reg
5645 && REGNO (reg
) < npi
->max_reg
)
5646 SET_BIT (nonnull_local
[current_block
->index
],
5647 REGNO (reg
) - npi
->min_reg
);
5651 /* Now compute global properties based on the local properties. This
5652 is a classic global availablity algorithm. */
5653 compute_available (nonnull_local
, nonnull_killed
,
5654 nonnull_avout
, nonnull_avin
);
5656 /* Now look at each bb and see if it ends with a compare of a value
5660 rtx last_insn
= bb
->end
;
5661 rtx condition
, earliest
;
5662 int compare_and_branch
;
5664 /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
5665 since BLOCK_REG[BB] is zero if this block did not end with a
5666 comparison against zero, this condition works. */
5667 if (block_reg
[bb
->index
] < npi
->min_reg
5668 || block_reg
[bb
->index
] >= npi
->max_reg
)
5671 /* LAST_INSN is a conditional jump. Get its condition. */
5672 condition
= get_condition (last_insn
, &earliest
);
5674 /* If we can't determine the condition then skip. */
5678 /* Is the register known to have a nonzero value? */
5679 if (!TEST_BIT (nonnull_avout
[bb
->index
], block_reg
[bb
->index
] - npi
->min_reg
))
5682 /* Try to compute whether the compare/branch at the loop end is one or
5683 two instructions. */
5684 if (earliest
== last_insn
)
5685 compare_and_branch
= 1;
5686 else if (earliest
== prev_nonnote_insn (last_insn
))
5687 compare_and_branch
= 2;
5691 /* We know the register in this comparison is nonnull at exit from
5692 this block. We can optimize this comparison. */
5693 if (GET_CODE (condition
) == NE
)
5697 new_jump
= emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn
)),
5699 JUMP_LABEL (new_jump
) = JUMP_LABEL (last_insn
);
5700 LABEL_NUSES (JUMP_LABEL (new_jump
))++;
5701 emit_barrier_after (new_jump
);
5704 something_changed
= 1;
5705 delete_insn (last_insn
);
5706 if (compare_and_branch
== 2)
5707 delete_insn (earliest
);
5708 purge_dead_edges (bb
);
5710 /* Don't check this block again. (Note that BLOCK_END is
5711 invalid here; we deleted the last instruction in the
5713 block_reg
[bb
->index
] = 0;
5716 return something_changed
;
5719 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
5722 This is conceptually similar to global constant/copy propagation and
5723 classic global CSE (it even uses the same dataflow equations as cprop).
5725 If a register is used as memory address with the form (mem (reg)), then we
5726 know that REG can not be zero at that point in the program. Any instruction
5727 which sets REG "kills" this property.
5729 So, if every path leading to a conditional branch has an available memory
5730 reference of that form, then we know the register can not have the value
5731 zero at the conditional branch.
5733 So we merely need to compute the local properies and propagate that data
5734 around the cfg, then optimize where possible.
5736 We run this pass two times. Once before CSE, then again after CSE. This
5737 has proven to be the most profitable approach. It is rare for new
5738 optimization opportunities of this nature to appear after the first CSE
5741 This could probably be integrated with global cprop with a little work. */
5744 delete_null_pointer_checks (f
)
5745 rtx f ATTRIBUTE_UNUSED
;
5747 sbitmap
*nonnull_avin
, *nonnull_avout
;
5748 unsigned int *block_reg
;
5753 struct null_pointer_info npi
;
5754 int something_changed
= 0;
5756 /* If we have only a single block, then there's nothing to do. */
5757 if (n_basic_blocks
<= 1)
5760 /* Trying to perform global optimizations on flow graphs which have
5761 a high connectivity will take a long time and is unlikely to be
5762 particularly useful.
5764 In normal circumstances a cfg should have about twice as many edges
5765 as blocks. But we do not want to punish small functions which have
5766 a couple switch statements. So we require a relatively large number
5767 of basic blocks and the ratio of edges to blocks to be high. */
5768 if (n_basic_blocks
> 1000 && n_edges
/ n_basic_blocks
>= 20)
5771 /* We need four bitmaps, each with a bit for each register in each
5773 max_reg
= max_reg_num ();
5774 regs_per_pass
= get_bitmap_width (4, last_basic_block
, max_reg
);
5776 /* Allocate bitmaps to hold local and global properties. */
5777 npi
.nonnull_local
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
5778 npi
.nonnull_killed
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
5779 nonnull_avin
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
5780 nonnull_avout
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
5782 /* Go through the basic blocks, seeing whether or not each block
5783 ends with a conditional branch whose condition is a comparison
5784 against zero. Record the register compared in BLOCK_REG. */
5785 block_reg
= (unsigned int *) xcalloc (last_basic_block
, sizeof (int));
5788 rtx last_insn
= bb
->end
;
5789 rtx condition
, earliest
, reg
;
5791 /* We only want conditional branches. */
5792 if (GET_CODE (last_insn
) != JUMP_INSN
5793 || !any_condjump_p (last_insn
)
5794 || !onlyjump_p (last_insn
))
5797 /* LAST_INSN is a conditional jump. Get its condition. */
5798 condition
= get_condition (last_insn
, &earliest
);
5800 /* If we were unable to get the condition, or it is not an equality
5801 comparison against zero then there's nothing we can do. */
5803 || (GET_CODE (condition
) != NE
&& GET_CODE (condition
) != EQ
)
5804 || GET_CODE (XEXP (condition
, 1)) != CONST_INT
5805 || (XEXP (condition
, 1)
5806 != CONST0_RTX (GET_MODE (XEXP (condition
, 0)))))
5809 /* We must be checking a register against zero. */
5810 reg
= XEXP (condition
, 0);
5811 if (GET_CODE (reg
) != REG
)
5814 block_reg
[bb
->index
] = REGNO (reg
);
5817 /* Go through the algorithm for each block of registers. */
5818 for (reg
= FIRST_PSEUDO_REGISTER
; reg
< max_reg
; reg
+= regs_per_pass
)
5821 npi
.max_reg
= MIN (reg
+ regs_per_pass
, max_reg
);
5822 something_changed
|= delete_null_pointer_checks_1 (block_reg
,
5828 /* Free the table of registers compared at the end of every block. */
5832 sbitmap_vector_free (npi
.nonnull_local
);
5833 sbitmap_vector_free (npi
.nonnull_killed
);
5834 sbitmap_vector_free (nonnull_avin
);
5835 sbitmap_vector_free (nonnull_avout
);
5837 return something_changed
;
5840 /* Code Hoisting variables and subroutines. */
5842 /* Very busy expressions. */
5843 static sbitmap
*hoist_vbein
;
5844 static sbitmap
*hoist_vbeout
;
5846 /* Hoistable expressions. */
5847 static sbitmap
*hoist_exprs
;
5849 /* Dominator bitmaps. */
5850 dominance_info dominators
;
5852 /* ??? We could compute post dominators and run this algorithm in
5853 reverse to perform tail merging, doing so would probably be
5854 more effective than the tail merging code in jump.c.
5856 It's unclear if tail merging could be run in parallel with
5857 code hoisting. It would be nice. */
5859 /* Allocate vars used for code hoisting analysis. */
5862 alloc_code_hoist_mem (n_blocks
, n_exprs
)
5863 int n_blocks
, n_exprs
;
5865 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5866 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5867 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5869 hoist_vbein
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5870 hoist_vbeout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5871 hoist_exprs
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5872 transpout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5875 /* Free vars used for code hoisting analysis. */
5878 free_code_hoist_mem ()
5880 sbitmap_vector_free (antloc
);
5881 sbitmap_vector_free (transp
);
5882 sbitmap_vector_free (comp
);
5884 sbitmap_vector_free (hoist_vbein
);
5885 sbitmap_vector_free (hoist_vbeout
);
5886 sbitmap_vector_free (hoist_exprs
);
5887 sbitmap_vector_free (transpout
);
5889 free_dominance_info (dominators
);
5892 /* Compute the very busy expressions at entry/exit from each block.
5894 An expression is very busy if all paths from a given point
5895 compute the expression. */
5898 compute_code_hoist_vbeinout ()
5900 int changed
, passes
;
5903 sbitmap_vector_zero (hoist_vbeout
, last_basic_block
);
5904 sbitmap_vector_zero (hoist_vbein
, last_basic_block
);
5913 /* We scan the blocks in the reverse order to speed up
5915 FOR_EACH_BB_REVERSE (bb
)
5917 changed
|= sbitmap_a_or_b_and_c_cg (hoist_vbein
[bb
->index
], antloc
[bb
->index
],
5918 hoist_vbeout
[bb
->index
], transp
[bb
->index
]);
5919 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
5920 sbitmap_intersection_of_succs (hoist_vbeout
[bb
->index
], hoist_vbein
, bb
->index
);
5927 fprintf (gcse_file
, "hoisting vbeinout computation: %d passes\n", passes
);
5930 /* Top level routine to do the dataflow analysis needed by code hoisting. */
5933 compute_code_hoist_data ()
5935 compute_local_properties (transp
, comp
, antloc
, 0);
5936 compute_transpout ();
5937 compute_code_hoist_vbeinout ();
5938 dominators
= calculate_dominance_info (CDI_DOMINATORS
);
5940 fprintf (gcse_file
, "\n");
5943 /* Determine if the expression identified by EXPR_INDEX would
5944 reach BB unimpared if it was placed at the end of EXPR_BB.
5946 It's unclear exactly what Muchnick meant by "unimpared". It seems
5947 to me that the expression must either be computed or transparent in
5948 *every* block in the path(s) from EXPR_BB to BB. Any other definition
5949 would allow the expression to be hoisted out of loops, even if
5950 the expression wasn't a loop invariant.
5952 Contrast this to reachability for PRE where an expression is
5953 considered reachable if *any* path reaches instead of *all*
5957 hoist_expr_reaches_here_p (expr_bb
, expr_index
, bb
, visited
)
5958 basic_block expr_bb
;
5964 int visited_allocated_locally
= 0;
5967 if (visited
== NULL
)
5969 visited_allocated_locally
= 1;
5970 visited
= xcalloc (last_basic_block
, 1);
5973 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
5975 basic_block pred_bb
= pred
->src
;
5977 if (pred
->src
== ENTRY_BLOCK_PTR
)
5979 else if (pred_bb
== expr_bb
)
5981 else if (visited
[pred_bb
->index
])
5984 /* Does this predecessor generate this expression? */
5985 else if (TEST_BIT (comp
[pred_bb
->index
], expr_index
))
5987 else if (! TEST_BIT (transp
[pred_bb
->index
], expr_index
))
5993 visited
[pred_bb
->index
] = 1;
5994 if (! hoist_expr_reaches_here_p (expr_bb
, expr_index
,
5999 if (visited_allocated_locally
)
6002 return (pred
== NULL
);
6005 /* Actually perform code hoisting. */
6010 basic_block bb
, dominated
;
6012 unsigned int domby_len
;
6014 struct expr
**index_map
;
6017 sbitmap_vector_zero (hoist_exprs
, last_basic_block
);
6019 /* Compute a mapping from expression number (`bitmap_index') to
6020 hash table entry. */
6022 index_map
= (struct expr
**) xcalloc (n_exprs
, sizeof (struct expr
*));
6023 for (i
= 0; i
< expr_hash_table_size
; i
++)
6024 for (expr
= expr_hash_table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
6025 index_map
[expr
->bitmap_index
] = expr
;
6027 /* Walk over each basic block looking for potentially hoistable
6028 expressions, nothing gets hoisted from the entry block. */
6032 int insn_inserted_p
;
6034 domby_len
= get_dominated_by (dominators
, bb
, &domby
);
6035 /* Examine each expression that is very busy at the exit of this
6036 block. These are the potentially hoistable expressions. */
6037 for (i
= 0; i
< hoist_vbeout
[bb
->index
]->n_bits
; i
++)
6041 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
)
6042 && TEST_BIT (transpout
[bb
->index
], i
))
6044 /* We've found a potentially hoistable expression, now
6045 we look at every block BB dominates to see if it
6046 computes the expression. */
6047 for (j
= 0; j
< domby_len
; j
++)
6049 dominated
= domby
[j
];
6050 /* Ignore self dominance. */
6051 if (bb
== dominated
)
6053 /* We've found a dominated block, now see if it computes
6054 the busy expression and whether or not moving that
6055 expression to the "beginning" of that block is safe. */
6056 if (!TEST_BIT (antloc
[dominated
->index
], i
))
6059 /* Note if the expression would reach the dominated block
6060 unimpared if it was placed at the end of BB.
6062 Keep track of how many times this expression is hoistable
6063 from a dominated block into BB. */
6064 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
6068 /* If we found more than one hoistable occurrence of this
6069 expression, then note it in the bitmap of expressions to
6070 hoist. It makes no sense to hoist things which are computed
6071 in only one BB, and doing so tends to pessimize register
6072 allocation. One could increase this value to try harder
6073 to avoid any possible code expansion due to register
6074 allocation issues; however experiments have shown that
6075 the vast majority of hoistable expressions are only movable
6076 from two successors, so raising this threshhold is likely
6077 to nullify any benefit we get from code hoisting. */
6080 SET_BIT (hoist_exprs
[bb
->index
], i
);
6085 /* If we found nothing to hoist, then quit now. */
6092 /* Loop over all the hoistable expressions. */
6093 for (i
= 0; i
< hoist_exprs
[bb
->index
]->n_bits
; i
++)
6095 /* We want to insert the expression into BB only once, so
6096 note when we've inserted it. */
6097 insn_inserted_p
= 0;
6099 /* These tests should be the same as the tests above. */
6100 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
))
6102 /* We've found a potentially hoistable expression, now
6103 we look at every block BB dominates to see if it
6104 computes the expression. */
6105 for (j
= 0; j
< domby_len
; j
++)
6107 dominated
= domby
[j
];
6108 /* Ignore self dominance. */
6109 if (bb
== dominated
)
6112 /* We've found a dominated block, now see if it computes
6113 the busy expression and whether or not moving that
6114 expression to the "beginning" of that block is safe. */
6115 if (!TEST_BIT (antloc
[dominated
->index
], i
))
6118 /* The expression is computed in the dominated block and
6119 it would be safe to compute it at the start of the
6120 dominated block. Now we have to determine if the
6121 expression would reach the dominated block if it was
6122 placed at the end of BB. */
6123 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
6125 struct expr
*expr
= index_map
[i
];
6126 struct occr
*occr
= expr
->antic_occr
;
6130 /* Find the right occurrence of this expression. */
6131 while (BLOCK_FOR_INSN (occr
->insn
) != dominated
&& occr
)
6134 /* Should never happen. */
6140 set
= single_set (insn
);
6144 /* Create a pseudo-reg to store the result of reaching
6145 expressions into. Get the mode for the new pseudo
6146 from the mode of the original destination pseudo. */
6147 if (expr
->reaching_reg
== NULL
)
6149 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
6151 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
6153 occr
->deleted_p
= 1;
6154 if (!insn_inserted_p
)
6156 insert_insn_end_bb (index_map
[i
], bb
, 0);
6157 insn_inserted_p
= 1;
6169 /* Top level routine to perform one code hoisting (aka unification) pass
6171 Return non-zero if a change was made. */
6174 one_code_hoisting_pass ()
6178 alloc_expr_hash_table (max_cuid
);
6179 compute_expr_hash_table ();
6181 dump_hash_table (gcse_file
, "Code Hosting Expressions", expr_hash_table
,
6182 expr_hash_table_size
, n_exprs
);
6186 alloc_code_hoist_mem (last_basic_block
, n_exprs
);
6187 compute_code_hoist_data ();
6189 free_code_hoist_mem ();
6192 free_expr_hash_table ();
6197 /* Here we provide the things required to do store motion towards
6198 the exit. In order for this to be effective, gcse also needed to
6199 be taught how to move a load when it is kill only by a store to itself.
6204 void foo(float scale)
6206 for (i=0; i<10; i++)
6210 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
6211 the load out since its live around the loop, and stored at the bottom
6214 The 'Load Motion' referred to and implemented in this file is
6215 an enhancement to gcse which when using edge based lcm, recognizes
6216 this situation and allows gcse to move the load out of the loop.
6218 Once gcse has hoisted the load, store motion can then push this
6219 load towards the exit, and we end up with no loads or stores of 'i'
6222 /* This will search the ldst list for a matching expression. If it
6223 doesn't find one, we create one and initialize it. */
6225 static struct ls_expr
*
6229 struct ls_expr
* ptr
;
6231 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6232 if (expr_equiv_p (ptr
->pattern
, x
))
6237 ptr
= (struct ls_expr
*) xmalloc (sizeof (struct ls_expr
));
6239 ptr
->next
= pre_ldst_mems
;
6242 ptr
->loads
= NULL_RTX
;
6243 ptr
->stores
= NULL_RTX
;
6244 ptr
->reaching_reg
= NULL_RTX
;
6247 ptr
->hash_index
= 0;
6248 pre_ldst_mems
= ptr
;
6254 /* Free up an individual ldst entry. */
6257 free_ldst_entry (ptr
)
6258 struct ls_expr
* ptr
;
6260 free_INSN_LIST_list (& ptr
->loads
);
6261 free_INSN_LIST_list (& ptr
->stores
);
6266 /* Free up all memory associated with the ldst list. */
6271 while (pre_ldst_mems
)
6273 struct ls_expr
* tmp
= pre_ldst_mems
;
6275 pre_ldst_mems
= pre_ldst_mems
->next
;
6277 free_ldst_entry (tmp
);
6280 pre_ldst_mems
= NULL
;
6283 /* Dump debugging info about the ldst list. */
6286 print_ldst_list (file
)
6289 struct ls_expr
* ptr
;
6291 fprintf (file
, "LDST list: \n");
6293 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6295 fprintf (file
, " Pattern (%3d): ", ptr
->index
);
6297 print_rtl (file
, ptr
->pattern
);
6299 fprintf (file
, "\n Loads : ");
6302 print_rtl (file
, ptr
->loads
);
6304 fprintf (file
, "(nil)");
6306 fprintf (file
, "\n Stores : ");
6309 print_rtl (file
, ptr
->stores
);
6311 fprintf (file
, "(nil)");
6313 fprintf (file
, "\n\n");
6316 fprintf (file
, "\n");
6319 /* Returns 1 if X is in the list of ldst only expressions. */
6321 static struct ls_expr
*
6322 find_rtx_in_ldst (x
)
6325 struct ls_expr
* ptr
;
6327 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
6328 if (expr_equiv_p (ptr
->pattern
, x
) && ! ptr
->invalid
)
6334 /* Assign each element of the list of mems a monotonically increasing value. */
6339 struct ls_expr
* ptr
;
6342 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
6348 /* Return first item in the list. */
6350 static inline struct ls_expr
*
6353 return pre_ldst_mems
;
6356 /* Return the next item in ther list after the specified one. */
6358 static inline struct ls_expr
*
6360 struct ls_expr
* ptr
;
6365 /* Load Motion for loads which only kill themselves. */
6367 /* Return true if x is a simple MEM operation, with no registers or
6368 side effects. These are the types of loads we consider for the
6369 ld_motion list, otherwise we let the usual aliasing take care of it. */
6375 if (GET_CODE (x
) != MEM
)
6378 if (MEM_VOLATILE_P (x
))
6381 if (GET_MODE (x
) == BLKmode
)
6384 if (!rtx_varies_p (XEXP (x
, 0), 0))
6390 /* Make sure there isn't a buried reference in this pattern anywhere.
6391 If there is, invalidate the entry for it since we're not capable
6392 of fixing it up just yet.. We have to be sure we know about ALL
6393 loads since the aliasing code will allow all entries in the
6394 ld_motion list to not-alias itself. If we miss a load, we will get
6395 the wrong value since gcse might common it and we won't know to
6399 invalidate_any_buried_refs (x
)
6404 struct ls_expr
* ptr
;
6406 /* Invalidate it in the list. */
6407 if (GET_CODE (x
) == MEM
&& simple_mem (x
))
6409 ptr
= ldst_entry (x
);
6413 /* Recursively process the insn. */
6414 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
6416 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0; i
--)
6419 invalidate_any_buried_refs (XEXP (x
, i
));
6420 else if (fmt
[i
] == 'E')
6421 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
6422 invalidate_any_buried_refs (XVECEXP (x
, i
, j
));
6426 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
6427 being defined as MEM loads and stores to symbols, with no
6428 side effects and no registers in the expression. If there are any
6429 uses/defs which don't match this criteria, it is invalidated and
6430 trimmed out later. */
6433 compute_ld_motion_mems ()
6435 struct ls_expr
* ptr
;
6439 pre_ldst_mems
= NULL
;
6443 for (insn
= bb
->head
;
6444 insn
&& insn
!= NEXT_INSN (bb
->end
);
6445 insn
= NEXT_INSN (insn
))
6447 if (GET_RTX_CLASS (GET_CODE (insn
)) == 'i')
6449 if (GET_CODE (PATTERN (insn
)) == SET
)
6451 rtx src
= SET_SRC (PATTERN (insn
));
6452 rtx dest
= SET_DEST (PATTERN (insn
));
6454 /* Check for a simple LOAD... */
6455 if (GET_CODE (src
) == MEM
&& simple_mem (src
))
6457 ptr
= ldst_entry (src
);
6458 if (GET_CODE (dest
) == REG
)
6459 ptr
->loads
= alloc_INSN_LIST (insn
, ptr
->loads
);
6465 /* Make sure there isn't a buried load somewhere. */
6466 invalidate_any_buried_refs (src
);
6469 /* Check for stores. Don't worry about aliased ones, they
6470 will block any movement we might do later. We only care
6471 about this exact pattern since those are the only
6472 circumstance that we will ignore the aliasing info. */
6473 if (GET_CODE (dest
) == MEM
&& simple_mem (dest
))
6475 ptr
= ldst_entry (dest
);
6477 if (GET_CODE (src
) != MEM
6478 && GET_CODE (src
) != ASM_OPERANDS
)
6479 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
6485 invalidate_any_buried_refs (PATTERN (insn
));
6491 /* Remove any references that have been either invalidated or are not in the
6492 expression list for pre gcse. */
6495 trim_ld_motion_mems ()
6497 struct ls_expr
* last
= NULL
;
6498 struct ls_expr
* ptr
= first_ls_expr ();
6502 int del
= ptr
->invalid
;
6503 struct expr
* expr
= NULL
;
6505 /* Delete if entry has been made invalid. */
6511 /* Delete if we cannot find this mem in the expression list. */
6512 for (i
= 0; i
< expr_hash_table_size
&& del
; i
++)
6514 for (expr
= expr_hash_table
[i
];
6516 expr
= expr
->next_same_hash
)
6517 if (expr_equiv_p (expr
->expr
, ptr
->pattern
))
6529 last
->next
= ptr
->next
;
6530 free_ldst_entry (ptr
);
6535 pre_ldst_mems
= pre_ldst_mems
->next
;
6536 free_ldst_entry (ptr
);
6537 ptr
= pre_ldst_mems
;
6542 /* Set the expression field if we are keeping it. */
6549 /* Show the world what we've found. */
6550 if (gcse_file
&& pre_ldst_mems
!= NULL
)
6551 print_ldst_list (gcse_file
);
6554 /* This routine will take an expression which we are replacing with
6555 a reaching register, and update any stores that are needed if
6556 that expression is in the ld_motion list. Stores are updated by
6557 copying their SRC to the reaching register, and then storeing
6558 the reaching register into the store location. These keeps the
6559 correct value in the reaching register for the loads. */
6562 update_ld_motion_stores (expr
)
6565 struct ls_expr
* mem_ptr
;
6567 if ((mem_ptr
= find_rtx_in_ldst (expr
->expr
)))
6569 /* We can try to find just the REACHED stores, but is shouldn't
6570 matter to set the reaching reg everywhere... some might be
6571 dead and should be eliminated later. */
6573 /* We replace SET mem = expr with
6575 SET mem = reg , where reg is the
6576 reaching reg used in the load. */
6577 rtx list
= mem_ptr
->stores
;
6579 for ( ; list
!= NULL_RTX
; list
= XEXP (list
, 1))
6581 rtx insn
= XEXP (list
, 0);
6582 rtx pat
= PATTERN (insn
);
6583 rtx src
= SET_SRC (pat
);
6584 rtx reg
= expr
->reaching_reg
;
6587 /* If we've already copied it, continue. */
6588 if (expr
->reaching_reg
== src
)
6593 fprintf (gcse_file
, "PRE: store updated with reaching reg ");
6594 print_rtl (gcse_file
, expr
->reaching_reg
);
6595 fprintf (gcse_file
, ":\n ");
6596 print_inline_rtx (gcse_file
, insn
, 8);
6597 fprintf (gcse_file
, "\n");
6600 copy
= gen_move_insn ( reg
, SET_SRC (pat
));
6601 new = emit_insn_before (copy
, insn
);
6602 record_one_set (REGNO (reg
), new);
6603 SET_SRC (pat
) = reg
;
6605 /* un-recognize this pattern since it's probably different now. */
6606 INSN_CODE (insn
) = -1;
6607 gcse_create_count
++;
6612 /* Store motion code. */
6614 /* This is used to communicate the target bitvector we want to use in the
6615 reg_set_info routine when called via the note_stores mechanism. */
6616 static sbitmap
* regvec
;
6618 /* Used in computing the reverse edge graph bit vectors. */
6619 static sbitmap
* st_antloc
;
6621 /* Global holding the number of store expressions we are dealing with. */
6622 static int num_stores
;
6624 /* Checks to set if we need to mark a register set. Called from note_stores. */
6627 reg_set_info (dest
, setter
, data
)
6628 rtx dest
, setter ATTRIBUTE_UNUSED
;
6629 void * data ATTRIBUTE_UNUSED
;
6631 if (GET_CODE (dest
) == SUBREG
)
6632 dest
= SUBREG_REG (dest
);
6634 if (GET_CODE (dest
) == REG
)
6635 SET_BIT (*regvec
, REGNO (dest
));
6638 /* Return non-zero if the register operands of expression X are killed
6639 anywhere in basic block BB. */
6642 store_ops_ok (x
, bb
)
6650 /* Repeat is used to turn tail-recursion into iteration. */
6656 code
= GET_CODE (x
);
6660 /* If a reg has changed after us in this
6661 block, the operand has been killed. */
6662 return TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
));
6690 i
= GET_RTX_LENGTH (code
) - 1;
6691 fmt
= GET_RTX_FORMAT (code
);
6697 rtx tem
= XEXP (x
, i
);
6699 /* If we are about to do the last recursive call
6700 needed at this level, change it into iteration.
6701 This function is called enough to be worth it. */
6708 if (! store_ops_ok (tem
, bb
))
6711 else if (fmt
[i
] == 'E')
6715 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
6717 if (! store_ops_ok (XVECEXP (x
, i
, j
), bb
))
6726 /* Determine whether insn is MEM store pattern that we will consider moving. */
6729 find_moveable_store (insn
)
6732 struct ls_expr
* ptr
;
6733 rtx dest
= PATTERN (insn
);
6735 if (GET_CODE (dest
) != SET
6736 || GET_CODE (SET_SRC (dest
)) == ASM_OPERANDS
)
6739 dest
= SET_DEST (dest
);
6741 if (GET_CODE (dest
) != MEM
|| MEM_VOLATILE_P (dest
)
6742 || GET_MODE (dest
) == BLKmode
)
6745 if (GET_CODE (XEXP (dest
, 0)) != SYMBOL_REF
)
6748 if (rtx_varies_p (XEXP (dest
, 0), 0))
6751 ptr
= ldst_entry (dest
);
6752 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
6755 /* Perform store motion. Much like gcse, except we move expressions the
6756 other way by looking at the flowgraph in reverse. */
6759 compute_store_table ()
6766 max_gcse_regno
= max_reg_num ();
6768 reg_set_in_block
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
,
6770 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
6773 /* Find all the stores we care about. */
6776 regvec
= & (reg_set_in_block
[bb
->index
]);
6777 for (insn
= bb
->end
;
6778 insn
&& insn
!= PREV_INSN (bb
->end
);
6779 insn
= PREV_INSN (insn
))
6781 /* Ignore anything that is not a normal insn. */
6782 if (! INSN_P (insn
))
6785 if (GET_CODE (insn
) == CALL_INSN
)
6787 bool clobbers_all
= false;
6788 #ifdef NON_SAVING_SETJMP
6789 if (NON_SAVING_SETJMP
6790 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
6791 clobbers_all
= true;
6794 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
6796 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
6797 SET_BIT (reg_set_in_block
[bb
->index
], regno
);
6800 pat
= PATTERN (insn
);
6801 note_stores (pat
, reg_set_info
, NULL
);
6803 /* Now that we've marked regs, look for stores. */
6804 if (GET_CODE (pat
) == SET
)
6805 find_moveable_store (insn
);
6809 ret
= enumerate_ldsts ();
6813 fprintf (gcse_file
, "Store Motion Expressions.\n");
6814 print_ldst_list (gcse_file
);
6820 /* Check to see if the load X is aliased with STORE_PATTERN. */
6823 load_kills_store (x
, store_pattern
)
6824 rtx x
, store_pattern
;
6826 if (true_dependence (x
, GET_MODE (x
), store_pattern
, rtx_addr_varies_p
))
6831 /* Go through the entire insn X, looking for any loads which might alias
6832 STORE_PATTERN. Return 1 if found. */
6835 find_loads (x
, store_pattern
)
6836 rtx x
, store_pattern
;
6845 if (GET_CODE (x
) == SET
)
6848 if (GET_CODE (x
) == MEM
)
6850 if (load_kills_store (x
, store_pattern
))
6854 /* Recursively process the insn. */
6855 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
6857 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0 && !ret
; i
--)
6860 ret
|= find_loads (XEXP (x
, i
), store_pattern
);
6861 else if (fmt
[i
] == 'E')
6862 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
6863 ret
|= find_loads (XVECEXP (x
, i
, j
), store_pattern
);
6868 /* Check if INSN kills the store pattern X (is aliased with it).
6869 Return 1 if it it does. */
6872 store_killed_in_insn (x
, insn
)
6875 if (GET_RTX_CLASS (GET_CODE (insn
)) != 'i')
6878 if (GET_CODE (insn
) == CALL_INSN
)
6880 /* A normal or pure call might read from pattern,
6881 but a const call will not. */
6882 return ! CONST_OR_PURE_CALL_P (insn
) || pure_call_p (insn
);
6885 if (GET_CODE (PATTERN (insn
)) == SET
)
6887 rtx pat
= PATTERN (insn
);
6888 /* Check for memory stores to aliased objects. */
6889 if (GET_CODE (SET_DEST (pat
)) == MEM
&& !expr_equiv_p (SET_DEST (pat
), x
))
6890 /* pretend its a load and check for aliasing. */
6891 if (find_loads (SET_DEST (pat
), x
))
6893 return find_loads (SET_SRC (pat
), x
);
6896 return find_loads (PATTERN (insn
), x
);
6899 /* Returns 1 if the expression X is loaded or clobbered on or after INSN
6900 within basic block BB. */
6903 store_killed_after (x
, insn
, bb
)
6912 /* Check if the register operands of the store are OK in this block.
6913 Note that if registers are changed ANYWHERE in the block, we'll
6914 decide we can't move it, regardless of whether it changed above
6915 or below the store. This could be improved by checking the register
6916 operands while lookinng for aliasing in each insn. */
6917 if (!store_ops_ok (XEXP (x
, 0), bb
))
6920 for ( ; insn
&& insn
!= NEXT_INSN (last
); insn
= NEXT_INSN (insn
))
6921 if (store_killed_in_insn (x
, insn
))
6927 /* Returns 1 if the expression X is loaded or clobbered on or before INSN
6928 within basic block BB. */
6930 store_killed_before (x
, insn
, bb
)
6934 rtx first
= bb
->head
;
6937 return store_killed_in_insn (x
, insn
);
6939 /* Check if the register operands of the store are OK in this block.
6940 Note that if registers are changed ANYWHERE in the block, we'll
6941 decide we can't move it, regardless of whether it changed above
6942 or below the store. This could be improved by checking the register
6943 operands while lookinng for aliasing in each insn. */
6944 if (!store_ops_ok (XEXP (x
, 0), bb
))
6947 for ( ; insn
&& insn
!= PREV_INSN (first
); insn
= PREV_INSN (insn
))
6948 if (store_killed_in_insn (x
, insn
))
6954 #define ANTIC_STORE_LIST(x) ((x)->loads)
6955 #define AVAIL_STORE_LIST(x) ((x)->stores)
6957 /* Given the table of available store insns at the end of blocks,
6958 determine which ones are not killed by aliasing, and generate
6959 the appropriate vectors for gen and killed. */
6961 build_store_vectors ()
6965 struct ls_expr
* ptr
;
6967 /* Build the gen_vector. This is any store in the table which is not killed
6968 by aliasing later in its block. */
6969 ae_gen
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
6970 sbitmap_vector_zero (ae_gen
, last_basic_block
);
6972 st_antloc
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
6973 sbitmap_vector_zero (st_antloc
, last_basic_block
);
6975 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6977 /* Put all the stores into either the antic list, or the avail list,
6979 rtx store_list
= ptr
->stores
;
6980 ptr
->stores
= NULL_RTX
;
6982 for (st
= store_list
; st
!= NULL
; st
= XEXP (st
, 1))
6984 insn
= XEXP (st
, 0);
6985 bb
= BLOCK_FOR_INSN (insn
);
6987 if (!store_killed_after (ptr
->pattern
, insn
, bb
))
6989 /* If we've already seen an availale expression in this block,
6990 we can delete the one we saw already (It occurs earlier in
6991 the block), and replace it with this one). We'll copy the
6992 old SRC expression to an unused register in case there
6993 are any side effects. */
6994 if (TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
6996 /* Find previous store. */
6998 for (st
= AVAIL_STORE_LIST (ptr
); st
; st
= XEXP (st
, 1))
6999 if (BLOCK_FOR_INSN (XEXP (st
, 0)) == bb
)
7003 rtx r
= gen_reg_rtx (GET_MODE (ptr
->pattern
));
7005 fprintf (gcse_file
, "Removing redundant store:\n");
7006 replace_store_insn (r
, XEXP (st
, 0), bb
);
7007 XEXP (st
, 0) = insn
;
7011 SET_BIT (ae_gen
[bb
->index
], ptr
->index
);
7012 AVAIL_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
,
7013 AVAIL_STORE_LIST (ptr
));
7016 if (!store_killed_before (ptr
->pattern
, insn
, bb
))
7018 SET_BIT (st_antloc
[BLOCK_NUM (insn
)], ptr
->index
);
7019 ANTIC_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
,
7020 ANTIC_STORE_LIST (ptr
));
7024 /* Free the original list of store insns. */
7025 free_INSN_LIST_list (&store_list
);
7028 ae_kill
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7029 sbitmap_vector_zero (ae_kill
, last_basic_block
);
7031 transp
= (sbitmap
*) sbitmap_vector_alloc (last_basic_block
, num_stores
);
7032 sbitmap_vector_zero (transp
, last_basic_block
);
7034 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7037 if (store_killed_after (ptr
->pattern
, b
->head
, b
))
7039 /* The anticipatable expression is not killed if it's gen'd. */
7041 We leave this check out for now. If we have a code sequence
7042 in a block which looks like:
7046 We should flag this as having an ANTIC expression, NOT
7047 transparent, NOT killed, and AVAIL.
7048 Unfortunately, since we haven't re-written all loads to
7049 use the reaching reg, we'll end up doing an incorrect
7050 Load in the middle here if we push the store down. It happens in
7051 gcc.c-torture/execute/960311-1.c with -O3
7052 If we always kill it in this case, we'll sometimes do
7053 uneccessary work, but it shouldn't actually hurt anything.
7054 if (!TEST_BIT (ae_gen[b], ptr->index)). */
7055 SET_BIT (ae_kill
[b
->index
], ptr
->index
);
7058 SET_BIT (transp
[b
->index
], ptr
->index
);
7061 /* Any block with no exits calls some non-returning function, so
7062 we better mark the store killed here, or we might not store to
7063 it at all. If we knew it was abort, we wouldn't have to store,
7064 but we don't know that for sure. */
7067 fprintf (gcse_file
, "ST_avail and ST_antic (shown under loads..)\n");
7068 print_ldst_list (gcse_file
);
7069 dump_sbitmap_vector (gcse_file
, "st_antloc", "", st_antloc
, last_basic_block
);
7070 dump_sbitmap_vector (gcse_file
, "st_kill", "", ae_kill
, last_basic_block
);
7071 dump_sbitmap_vector (gcse_file
, "Transpt", "", transp
, last_basic_block
);
7072 dump_sbitmap_vector (gcse_file
, "st_avloc", "", ae_gen
, last_basic_block
);
7076 /* Insert an instruction at the begining of a basic block, and update
7077 the BLOCK_HEAD if needed. */
7080 insert_insn_start_bb (insn
, bb
)
7084 /* Insert at start of successor block. */
7085 rtx prev
= PREV_INSN (bb
->head
);
7086 rtx before
= bb
->head
;
7089 if (GET_CODE (before
) != CODE_LABEL
7090 && (GET_CODE (before
) != NOTE
7091 || NOTE_LINE_NUMBER (before
) != NOTE_INSN_BASIC_BLOCK
))
7094 if (prev
== bb
->end
)
7096 before
= NEXT_INSN (before
);
7099 insn
= emit_insn_after (insn
, prev
);
7103 fprintf (gcse_file
, "STORE_MOTION insert store at start of BB %d:\n",
7105 print_inline_rtx (gcse_file
, insn
, 6);
7106 fprintf (gcse_file
, "\n");
7110 /* This routine will insert a store on an edge. EXPR is the ldst entry for
7111 the memory reference, and E is the edge to insert it on. Returns non-zero
7112 if an edge insertion was performed. */
7115 insert_store (expr
, e
)
7116 struct ls_expr
* expr
;
7123 /* We did all the deleted before this insert, so if we didn't delete a
7124 store, then we haven't set the reaching reg yet either. */
7125 if (expr
->reaching_reg
== NULL_RTX
)
7128 reg
= expr
->reaching_reg
;
7129 insn
= gen_move_insn (expr
->pattern
, reg
);
7131 /* If we are inserting this expression on ALL predecessor edges of a BB,
7132 insert it at the start of the BB, and reset the insert bits on the other
7133 edges so we don't try to insert it on the other edges. */
7135 for (tmp
= e
->dest
->pred
; tmp
; tmp
= tmp
->pred_next
)
7137 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
7138 if (index
== EDGE_INDEX_NO_EDGE
)
7140 if (! TEST_BIT (pre_insert_map
[index
], expr
->index
))
7144 /* If tmp is NULL, we found an insertion on every edge, blank the
7145 insertion vector for these edges, and insert at the start of the BB. */
7146 if (!tmp
&& bb
!= EXIT_BLOCK_PTR
)
7148 for (tmp
= e
->dest
->pred
; tmp
; tmp
= tmp
->pred_next
)
7150 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
7151 RESET_BIT (pre_insert_map
[index
], expr
->index
);
7153 insert_insn_start_bb (insn
, bb
);
7157 /* We can't insert on this edge, so we'll insert at the head of the
7158 successors block. See Morgan, sec 10.5. */
7159 if ((e
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
7161 insert_insn_start_bb (insn
, bb
);
7165 insert_insn_on_edge (insn
, e
);
7169 fprintf (gcse_file
, "STORE_MOTION insert insn on edge (%d, %d):\n",
7170 e
->src
->index
, e
->dest
->index
);
7171 print_inline_rtx (gcse_file
, insn
, 6);
7172 fprintf (gcse_file
, "\n");
7178 /* This routine will replace a store with a SET to a specified register. */
7181 replace_store_insn (reg
, del
, bb
)
7187 insn
= gen_move_insn (reg
, SET_SRC (PATTERN (del
)));
7188 insn
= emit_insn_after (insn
, del
);
7193 "STORE_MOTION delete insn in BB %d:\n ", bb
->index
);
7194 print_inline_rtx (gcse_file
, del
, 6);
7195 fprintf (gcse_file
, "\nSTORE MOTION replaced with insn:\n ");
7196 print_inline_rtx (gcse_file
, insn
, 6);
7197 fprintf (gcse_file
, "\n");
7204 /* Delete a store, but copy the value that would have been stored into
7205 the reaching_reg for later storing. */
7208 delete_store (expr
, bb
)
7209 struct ls_expr
* expr
;
7214 if (expr
->reaching_reg
== NULL_RTX
)
7215 expr
->reaching_reg
= gen_reg_rtx (GET_MODE (expr
->pattern
));
7218 /* If there is more than 1 store, the earlier ones will be dead,
7219 but it doesn't hurt to replace them here. */
7220 reg
= expr
->reaching_reg
;
7222 for (i
= AVAIL_STORE_LIST (expr
); i
; i
= XEXP (i
, 1))
7225 if (BLOCK_FOR_INSN (del
) == bb
)
7227 /* We know there is only one since we deleted redundant
7228 ones during the available computation. */
7229 replace_store_insn (reg
, del
, bb
);
7235 /* Free memory used by store motion. */
7238 free_store_memory ()
7243 sbitmap_vector_free (ae_gen
);
7245 sbitmap_vector_free (ae_kill
);
7247 sbitmap_vector_free (transp
);
7249 sbitmap_vector_free (st_antloc
);
7251 sbitmap_vector_free (pre_insert_map
);
7253 sbitmap_vector_free (pre_delete_map
);
7254 if (reg_set_in_block
)
7255 sbitmap_vector_free (reg_set_in_block
);
7257 ae_gen
= ae_kill
= transp
= st_antloc
= NULL
;
7258 pre_insert_map
= pre_delete_map
= reg_set_in_block
= NULL
;
7261 /* Perform store motion. Much like gcse, except we move expressions the
7262 other way by looking at the flowgraph in reverse. */
7269 struct ls_expr
* ptr
;
7270 int update_flow
= 0;
7274 fprintf (gcse_file
, "before store motion\n");
7275 print_rtl (gcse_file
, get_insns ());
7279 init_alias_analysis ();
7281 /* Find all the stores that are live to the end of their block. */
7282 num_stores
= compute_store_table ();
7283 if (num_stores
== 0)
7285 sbitmap_vector_free (reg_set_in_block
);
7286 end_alias_analysis ();
7290 /* Now compute whats actually available to move. */
7291 add_noreturn_fake_exit_edges ();
7292 build_store_vectors ();
7294 edge_list
= pre_edge_rev_lcm (gcse_file
, num_stores
, transp
, ae_gen
,
7295 st_antloc
, ae_kill
, &pre_insert_map
,
7298 /* Now we want to insert the new stores which are going to be needed. */
7299 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7302 if (TEST_BIT (pre_delete_map
[bb
->index
], ptr
->index
))
7303 delete_store (ptr
, bb
);
7305 for (x
= 0; x
< NUM_EDGES (edge_list
); x
++)
7306 if (TEST_BIT (pre_insert_map
[x
], ptr
->index
))
7307 update_flow
|= insert_store (ptr
, INDEX_EDGE (edge_list
, x
));
7311 commit_edge_insertions ();
7313 free_store_memory ();
7314 free_edge_list (edge_list
);
7315 remove_fake_edges ();
7316 end_alias_analysis ();
7319 #include "gt-gcse.h"