1 /* Global common subexpression elimination/Partial redundancy elimination
2 and global constant/copy propagation for GNU compiler.
3 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
24 - reordering of memory allocation and freeing to be more space efficient
25 - do rough calc of how many regs are needed in each block, and a rough
26 calc of how many regs are available in each class and use that to
27 throttle back the code in cases where RTX_COST is minimal.
28 - a store to the same address as a load does not kill the load if the
29 source of the store is also the destination of the load. Handling this
30 allows more load motion, particularly out of loops.
31 - ability to realloc sbitmap vectors would allow one initial computation
32 of reg_set_in_block with only subsequent additions, rather than
33 recomputing it for each pass
37 /* References searched while implementing this.
39 Compilers Principles, Techniques and Tools
43 Global Optimization by Suppression of Partial Redundancies
45 communications of the acm, Vol. 22, Num. 2, Feb. 1979
47 A Portable Machine-Independent Global Optimizer - Design and Measurements
49 Stanford Ph.D. thesis, Dec. 1983
51 A Fast Algorithm for Code Movement Optimization
53 SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988
55 A Solution to a Problem with Morel and Renvoise's
56 Global Optimization by Suppression of Partial Redundancies
57 K-H Drechsler, M.P. Stadel
58 ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988
60 Practical Adaptation of the Global Optimization
61 Algorithm of Morel and Renvoise
63 ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991
65 Efficiently Computing Static Single Assignment Form and the Control
67 R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck
68 ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991
71 J. Knoop, O. Ruthing, B. Steffen
72 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
74 What's In a Region? Or Computing Control Dependence Regions in Near-Linear
75 Time for Reducible Flow Control
77 ACM Letters on Programming Languages and Systems,
78 Vol. 2, Num. 1-4, Mar-Dec 1993
80 An Efficient Representation for Sparse Sets
81 Preston Briggs, Linda Torczon
82 ACM Letters on Programming Languages and Systems,
83 Vol. 2, Num. 1-4, Mar-Dec 1993
85 A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion
86 K-H Drechsler, M.P. Stadel
87 ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993
89 Partial Dead Code Elimination
90 J. Knoop, O. Ruthing, B. Steffen
91 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
93 Effective Partial Redundancy Elimination
94 P. Briggs, K.D. Cooper
95 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
97 The Program Structure Tree: Computing Control Regions in Linear Time
98 R. Johnson, D. Pearson, K. Pingali
99 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
101 Optimal Code Motion: Theory and Practice
102 J. Knoop, O. Ruthing, B. Steffen
103 ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994
105 The power of assignment motion
106 J. Knoop, O. Ruthing, B. Steffen
107 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
109 Global code motion / global value numbering
111 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
113 Value Driven Redundancy Elimination
115 Rice University Ph.D. thesis, Apr. 1996
119 Massively Scalar Compiler Project, Rice University, Sep. 1996
121 High Performance Compilers for Parallel Computing
125 Advanced Compiler Design and Implementation
127 Morgan Kaufmann, 1997
129 Building an Optimizing Compiler
133 People wishing to speed up the code here should read:
134 Elimination Algorithms for Data Flow Analysis
135 B.G. Ryder, M.C. Paull
136 ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986
138 How to Analyze Large Programs Efficiently and Informatively
139 D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck
140 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
142 People wishing to do something different can find various possibilities
143 in the above papers and elsewhere.
148 #include "coretypes.h"
155 #include "hard-reg-set.h"
158 #include "insn-config.h"
160 #include "basic-block.h"
162 #include "function.h"
171 /* Propagate flow information through back edges and thus enable PRE's
172 moving loop invariant calculations out of loops.
174 Originally this tended to create worse overall code, but several
175 improvements during the development of PRE seem to have made following
176 back edges generally a win.
178 Note much of the loop invariant code motion done here would normally
179 be done by loop.c, which has more heuristics for when to move invariants
180 out of loops. At some point we might need to move some of those
181 heuristics into gcse.c. */
183 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
184 are a superset of those done by GCSE.
186 We perform the following steps:
188 1) Compute basic block information.
190 2) Compute table of places where registers are set.
192 3) Perform copy/constant propagation.
194 4) Perform global cse.
196 5) Perform another pass of copy/constant propagation.
198 Two passes of copy/constant propagation are done because the first one
199 enables more GCSE and the second one helps to clean up the copies that
200 GCSE creates. This is needed more for PRE than for Classic because Classic
201 GCSE will try to use an existing register containing the common
202 subexpression rather than create a new one. This is harder to do for PRE
203 because of the code motion (which Classic GCSE doesn't do).
205 Expressions we are interested in GCSE-ing are of the form
206 (set (pseudo-reg) (expression)).
207 Function want_to_gcse_p says what these are.
209 PRE handles moving invariant expressions out of loops (by treating them as
210 partially redundant).
212 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
213 assignment) based GVN (global value numbering). L. T. Simpson's paper
214 (Rice University) on value numbering is a useful reference for this.
216 **********************
218 We used to support multiple passes but there are diminishing returns in
219 doing so. The first pass usually makes 90% of the changes that are doable.
220 A second pass can make a few more changes made possible by the first pass.
221 Experiments show any further passes don't make enough changes to justify
224 A study of spec92 using an unlimited number of passes:
225 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
226 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
227 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
229 It was found doing copy propagation between each pass enables further
232 PRE is quite expensive in complicated functions because the DFA can take
233 awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can
234 be modified if one wants to experiment.
236 **********************
238 The steps for PRE are:
240 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
242 2) Perform the data flow analysis for PRE.
244 3) Delete the redundant instructions
246 4) Insert the required copies [if any] that make the partially
247 redundant instructions fully redundant.
249 5) For other reaching expressions, insert an instruction to copy the value
250 to a newly created pseudo that will reach the redundant instruction.
252 The deletion is done first so that when we do insertions we
253 know which pseudo reg to use.
255 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
256 argue it is not. The number of iterations for the algorithm to converge
257 is typically 2-4 so I don't view it as that expensive (relatively speaking).
259 PRE GCSE depends heavily on the second CSE pass to clean up the copies
260 we create. To make an expression reach the place where it's redundant,
261 the result of the expression is copied to a new register, and the redundant
262 expression is deleted by replacing it with this new register. Classic GCSE
263 doesn't have this problem as much as it computes the reaching defs of
264 each register in each block and thus can try to use an existing register.
266 **********************
268 A fair bit of simplicity is created by creating small functions for simple
269 tasks, even when the function is only called in one place. This may
270 measurably slow things down [or may not] by creating more function call
271 overhead than is necessary. The source is laid out so that it's trivial
272 to make the affected functions inline so that one can measure what speed
273 up, if any, can be achieved, and maybe later when things settle things can
276 Help stamp out big monolithic functions! */
278 /* GCSE global vars. */
281 static FILE *gcse_file
;
283 /* Note whether or not we should run jump optimization after gcse. We
284 want to do this for two cases.
286 * If we changed any jumps via cprop.
288 * If we added any labels via edge splitting. */
290 static int run_jump_opt_after_gcse
;
292 /* Bitmaps are normally not included in debugging dumps.
293 However it's useful to be able to print them from GDB.
294 We could create special functions for this, but it's simpler to
295 just allow passing stderr to the dump_foo fns. Since stderr can
296 be a macro, we store a copy here. */
297 static FILE *debug_stderr
;
299 /* An obstack for our working variables. */
300 static struct obstack gcse_obstack
;
302 struct reg_use
{rtx reg_rtx
; };
304 /* Hash table of expressions. */
308 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
310 /* Index in the available expression bitmaps. */
312 /* Next entry with the same hash. */
313 struct expr
*next_same_hash
;
314 /* List of anticipatable occurrences in basic blocks in the function.
315 An "anticipatable occurrence" is one that is the first occurrence in the
316 basic block, the operands are not modified in the basic block prior
317 to the occurrence and the output is not used between the start of
318 the block and the occurrence. */
319 struct occr
*antic_occr
;
320 /* List of available occurrence in basic blocks in the function.
321 An "available occurrence" is one that is the last occurrence in the
322 basic block and the operands are not modified by following statements in
323 the basic block [including this insn]. */
324 struct occr
*avail_occr
;
325 /* Non-null if the computation is PRE redundant.
326 The value is the newly created pseudo-reg to record a copy of the
327 expression in all the places that reach the redundant copy. */
331 /* Occurrence of an expression.
332 There is one per basic block. If a pattern appears more than once the
333 last appearance is used [or first for anticipatable expressions]. */
337 /* Next occurrence of this expression. */
339 /* The insn that computes the expression. */
341 /* Nonzero if this [anticipatable] occurrence has been deleted. */
343 /* Nonzero if this [available] occurrence has been copied to
345 /* ??? This is mutually exclusive with deleted_p, so they could share
350 /* Expression and copy propagation hash tables.
351 Each hash table is an array of buckets.
352 ??? It is known that if it were an array of entries, structure elements
353 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
354 not clear whether in the final analysis a sufficient amount of memory would
355 be saved as the size of the available expression bitmaps would be larger
356 [one could build a mapping table without holes afterwards though].
357 Someday I'll perform the computation and figure it out. */
362 This is an array of `expr_hash_table_size' elements. */
365 /* Size of the hash table, in elements. */
368 /* Number of hash table elements. */
369 unsigned int n_elems
;
371 /* Whether the table is expression of copy propagation one. */
375 /* Expression hash table. */
376 static struct hash_table expr_hash_table
;
378 /* Copy propagation hash table. */
379 static struct hash_table set_hash_table
;
381 /* Mapping of uids to cuids.
382 Only real insns get cuids. */
383 static int *uid_cuid
;
385 /* Highest UID in UID_CUID. */
388 /* Get the cuid of an insn. */
389 #ifdef ENABLE_CHECKING
390 #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
392 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
395 /* Number of cuids. */
398 /* Mapping of cuids to insns. */
399 static rtx
*cuid_insn
;
401 /* Get insn from cuid. */
402 #define CUID_INSN(CUID) (cuid_insn[CUID])
404 /* Maximum register number in function prior to doing gcse + 1.
405 Registers created during this pass have regno >= max_gcse_regno.
406 This is named with "gcse" to not collide with global of same name. */
407 static unsigned int max_gcse_regno
;
409 /* Table of registers that are modified.
411 For each register, each element is a list of places where the pseudo-reg
414 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
415 requires knowledge of which blocks kill which regs [and thus could use
416 a bitmap instead of the lists `reg_set_table' uses].
418 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
419 num-regs) [however perhaps it may be useful to keep the data as is]. One
420 advantage of recording things this way is that `reg_set_table' is fairly
421 sparse with respect to pseudo regs but for hard regs could be fairly dense
422 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
423 up functions like compute_transp since in the case of pseudo-regs we only
424 need to iterate over the number of times a pseudo-reg is set, not over the
425 number of basic blocks [clearly there is a bit of a slow down in the cases
426 where a pseudo is set more than once in a block, however it is believed
427 that the net effect is to speed things up]. This isn't done for hard-regs
428 because recording call-clobbered hard-regs in `reg_set_table' at each
429 function call can consume a fair bit of memory, and iterating over
430 hard-regs stored this way in compute_transp will be more expensive. */
432 typedef struct reg_set
434 /* The next setting of this register. */
435 struct reg_set
*next
;
436 /* The insn where it was set. */
440 static reg_set
**reg_set_table
;
442 /* Size of `reg_set_table'.
443 The table starts out at max_gcse_regno + slop, and is enlarged as
445 static int reg_set_table_size
;
447 /* Amount to grow `reg_set_table' by when it's full. */
448 #define REG_SET_TABLE_SLOP 100
450 /* This is a list of expressions which are MEMs and will be used by load
452 Load motion tracks MEMs which aren't killed by
453 anything except itself. (ie, loads and stores to a single location).
454 We can then allow movement of these MEM refs with a little special
455 allowance. (all stores copy the same value to the reaching reg used
456 for the loads). This means all values used to store into memory must have
457 no side effects so we can re-issue the setter value.
458 Store Motion uses this structure as an expression table to track stores
459 which look interesting, and might be moveable towards the exit block. */
463 struct expr
* expr
; /* Gcse expression reference for LM. */
464 rtx pattern
; /* Pattern of this mem. */
465 rtx pattern_regs
; /* List of registers mentioned by the mem. */
466 rtx loads
; /* INSN list of loads seen. */
467 rtx stores
; /* INSN list of stores seen. */
468 struct ls_expr
* next
; /* Next in the list. */
469 int invalid
; /* Invalid for some reason. */
470 int index
; /* If it maps to a bitmap index. */
471 int hash_index
; /* Index when in a hash table. */
472 rtx reaching_reg
; /* Register to use when re-writing. */
475 /* Array of implicit set patterns indexed by basic block index. */
476 static rtx
*implicit_sets
;
478 /* Head of the list of load/store memory refs. */
479 static struct ls_expr
* pre_ldst_mems
= NULL
;
481 /* Bitmap containing one bit for each register in the program.
482 Used when performing GCSE to track which registers have been set since
483 the start of the basic block. */
484 static regset reg_set_bitmap
;
486 /* For each block, a bitmap of registers set in the block.
487 This is used by expr_killed_p and compute_transp.
488 It is computed during hash table computation and not by compute_sets
489 as it includes registers added since the last pass (or between cprop and
490 gcse) and it's currently not easy to realloc sbitmap vectors. */
491 static sbitmap
*reg_set_in_block
;
493 /* Array, indexed by basic block number for a list of insns which modify
494 memory within that block. */
495 static rtx
* modify_mem_list
;
496 bitmap modify_mem_list_set
;
498 /* This array parallels modify_mem_list, but is kept canonicalized. */
499 static rtx
* canon_modify_mem_list
;
500 bitmap canon_modify_mem_list_set
;
501 /* Various variables for statistics gathering. */
503 /* Memory used in a pass.
504 This isn't intended to be absolutely precise. Its intent is only
505 to keep an eye on memory usage. */
506 static int bytes_used
;
508 /* GCSE substitutions made. */
509 static int gcse_subst_count
;
510 /* Number of copy instructions created. */
511 static int gcse_create_count
;
512 /* Number of constants propagated. */
513 static int const_prop_count
;
514 /* Number of copys propagated. */
515 static int copy_prop_count
;
517 /* These variables are used by classic GCSE.
518 Normally they'd be defined a bit later, but `rd_gen' needs to
519 be declared sooner. */
521 /* Each block has a bitmap of each type.
522 The length of each blocks bitmap is:
524 max_cuid - for reaching definitions
525 n_exprs - for available expressions
527 Thus we view the bitmaps as 2 dimensional arrays. i.e.
528 rd_kill[block_num][cuid_num]
529 ae_kill[block_num][expr_num] */
531 /* For reaching defs */
532 static sbitmap
*rd_kill
, *rd_gen
, *reaching_defs
, *rd_out
;
534 /* for available exprs */
535 static sbitmap
*ae_kill
, *ae_gen
, *ae_in
, *ae_out
;
537 /* Objects of this type are passed around by the null-pointer check
539 struct null_pointer_info
541 /* The basic block being processed. */
542 basic_block current_block
;
543 /* The first register to be handled in this pass. */
544 unsigned int min_reg
;
545 /* One greater than the last register to be handled in this pass. */
546 unsigned int max_reg
;
547 sbitmap
*nonnull_local
;
548 sbitmap
*nonnull_killed
;
551 static void compute_can_copy (void);
552 static void *gmalloc (size_t) ATTRIBUTE_MALLOC
;
553 static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC
;
554 static void *grealloc (void *, size_t);
555 static void *gcse_alloc (unsigned long);
556 static void alloc_gcse_mem (rtx
);
557 static void free_gcse_mem (void);
558 static void alloc_reg_set_mem (int);
559 static void free_reg_set_mem (void);
560 static int get_bitmap_width (int, int, int);
561 static void record_one_set (int, rtx
);
562 static void replace_one_set (int, rtx
, rtx
);
563 static void record_set_info (rtx
, rtx
, void *);
564 static void compute_sets (rtx
);
565 static void hash_scan_insn (rtx
, struct hash_table
*, int);
566 static void hash_scan_set (rtx
, rtx
, struct hash_table
*);
567 static void hash_scan_clobber (rtx
, rtx
, struct hash_table
*);
568 static void hash_scan_call (rtx
, rtx
, struct hash_table
*);
569 static int want_to_gcse_p (rtx
);
570 static bool gcse_constant_p (rtx
);
571 static int oprs_unchanged_p (rtx
, rtx
, int);
572 static int oprs_anticipatable_p (rtx
, rtx
);
573 static int oprs_available_p (rtx
, rtx
);
574 static void insert_expr_in_table (rtx
, enum machine_mode
, rtx
, int, int,
575 struct hash_table
*);
576 static void insert_set_in_table (rtx
, rtx
, struct hash_table
*);
577 static unsigned int hash_expr (rtx
, enum machine_mode
, int *, int);
578 static unsigned int hash_expr_1 (rtx
, enum machine_mode
, int *);
579 static unsigned int hash_string_1 (const char *);
580 static unsigned int hash_set (int, int);
581 static int expr_equiv_p (rtx
, rtx
);
582 static void record_last_reg_set_info (rtx
, int);
583 static void record_last_mem_set_info (rtx
);
584 static void record_last_set_info (rtx
, rtx
, void *);
585 static void compute_hash_table (struct hash_table
*);
586 static void alloc_hash_table (int, struct hash_table
*, int);
587 static void free_hash_table (struct hash_table
*);
588 static void compute_hash_table_work (struct hash_table
*);
589 static void dump_hash_table (FILE *, const char *, struct hash_table
*);
590 static struct expr
*lookup_expr (rtx
, struct hash_table
*);
591 static struct expr
*lookup_set (unsigned int, struct hash_table
*);
592 static struct expr
*next_set (unsigned int, struct expr
*);
593 static void reset_opr_set_tables (void);
594 static int oprs_not_set_p (rtx
, rtx
);
595 static void mark_call (rtx
);
596 static void mark_set (rtx
, rtx
);
597 static void mark_clobber (rtx
, rtx
);
598 static void mark_oprs_set (rtx
);
599 static void alloc_cprop_mem (int, int);
600 static void free_cprop_mem (void);
601 static void compute_transp (rtx
, int, sbitmap
*, int);
602 static void compute_transpout (void);
603 static void compute_local_properties (sbitmap
*, sbitmap
*, sbitmap
*,
604 struct hash_table
*);
605 static void compute_cprop_data (void);
606 static void find_used_regs (rtx
*, void *);
607 static int try_replace_reg (rtx
, rtx
, rtx
);
608 static struct expr
*find_avail_set (int, rtx
);
609 static int cprop_jump (basic_block
, rtx
, rtx
, rtx
, rtx
);
610 static void mems_conflict_for_gcse_p (rtx
, rtx
, void *);
611 static int load_killed_in_block_p (basic_block
, int, rtx
, int);
612 static void canon_list_insert (rtx
, rtx
, void *);
613 static int cprop_insn (rtx
, int);
614 static int cprop (int);
615 static void find_implicit_sets (void);
616 static int one_cprop_pass (int, int, int);
617 static bool constprop_register (rtx
, rtx
, rtx
, int);
618 static struct expr
*find_bypass_set (int, int);
619 static bool reg_killed_on_edge (rtx
, edge
);
620 static int bypass_block (basic_block
, rtx
, rtx
);
621 static int bypass_conditional_jumps (void);
622 static void alloc_pre_mem (int, int);
623 static void free_pre_mem (void);
624 static void compute_pre_data (void);
625 static int pre_expr_reaches_here_p (basic_block
, struct expr
*,
627 static void insert_insn_end_bb (struct expr
*, basic_block
, int);
628 static void pre_insert_copy_insn (struct expr
*, rtx
);
629 static void pre_insert_copies (void);
630 static int pre_delete (void);
631 static int pre_gcse (void);
632 static int one_pre_gcse_pass (int);
633 static void add_label_notes (rtx
, rtx
);
634 static void alloc_code_hoist_mem (int, int);
635 static void free_code_hoist_mem (void);
636 static void compute_code_hoist_vbeinout (void);
637 static void compute_code_hoist_data (void);
638 static int hoist_expr_reaches_here_p (basic_block
, int, basic_block
, char *);
639 static void hoist_code (void);
640 static int one_code_hoisting_pass (void);
641 static void alloc_rd_mem (int, int);
642 static void free_rd_mem (void);
643 static void handle_rd_kill_set (rtx
, int, basic_block
);
644 static void compute_kill_rd (void);
645 static void compute_rd (void);
646 static void alloc_avail_expr_mem (int, int);
647 static void free_avail_expr_mem (void);
648 static void compute_ae_gen (struct hash_table
*);
649 static int expr_killed_p (rtx
, basic_block
);
650 static void compute_ae_kill (sbitmap
*, sbitmap
*, struct hash_table
*);
651 static int expr_reaches_here_p (struct occr
*, struct expr
*, basic_block
,
653 static rtx
computing_insn (struct expr
*, rtx
);
654 static int def_reaches_here_p (rtx
, rtx
);
655 static int can_disregard_other_sets (struct reg_set
**, rtx
, int);
656 static int handle_avail_expr (rtx
, struct expr
*);
657 static int classic_gcse (void);
658 static int one_classic_gcse_pass (int);
659 static void invalidate_nonnull_info (rtx
, rtx
, void *);
660 static int delete_null_pointer_checks_1 (unsigned int *, sbitmap
*, sbitmap
*,
661 struct null_pointer_info
*);
662 static rtx
process_insert_insn (struct expr
*);
663 static int pre_edge_insert (struct edge_list
*, struct expr
**);
664 static int expr_reaches_here_p_work (struct occr
*, struct expr
*,
665 basic_block
, int, char *);
666 static int pre_expr_reaches_here_p_work (basic_block
, struct expr
*,
667 basic_block
, char *);
668 static struct ls_expr
* ldst_entry (rtx
);
669 static void free_ldst_entry (struct ls_expr
*);
670 static void free_ldst_mems (void);
671 static void print_ldst_list (FILE *);
672 static struct ls_expr
* find_rtx_in_ldst (rtx
);
673 static int enumerate_ldsts (void);
674 static inline struct ls_expr
* first_ls_expr (void);
675 static inline struct ls_expr
* next_ls_expr (struct ls_expr
*);
676 static int simple_mem (rtx
);
677 static void invalidate_any_buried_refs (rtx
);
678 static void compute_ld_motion_mems (void);
679 static void trim_ld_motion_mems (void);
680 static void update_ld_motion_stores (struct expr
*);
681 static void reg_set_info (rtx
, rtx
, void *);
682 static bool store_ops_ok (rtx
, int *);
683 static rtx
extract_mentioned_regs (rtx
);
684 static rtx
extract_mentioned_regs_helper (rtx
, rtx
);
685 static void find_moveable_store (rtx
, int *, int *);
686 static int compute_store_table (void);
687 static bool load_kills_store (rtx
, rtx
, int);
688 static bool find_loads (rtx
, rtx
, int);
689 static bool store_killed_in_insn (rtx
, rtx
, rtx
, int);
690 static bool store_killed_after (rtx
, rtx
, rtx
, basic_block
, int *, rtx
*);
691 static bool store_killed_before (rtx
, rtx
, rtx
, basic_block
, int *);
692 static void build_store_vectors (void);
693 static void insert_insn_start_bb (rtx
, basic_block
);
694 static int insert_store (struct ls_expr
*, edge
);
695 static void remove_reachable_equiv_notes (basic_block
, struct ls_expr
*);
696 static void replace_store_insn (rtx
, rtx
, basic_block
, struct ls_expr
*);
697 static void delete_store (struct ls_expr
*, basic_block
);
698 static void free_store_memory (void);
699 static void store_motion (void);
700 static void free_insn_expr_list_list (rtx
*);
701 static void clear_modify_mem_tables (void);
702 static void free_modify_mem_tables (void);
703 static rtx
gcse_emit_move_after (rtx
, rtx
, rtx
);
704 static void local_cprop_find_used_regs (rtx
*, void *);
705 static bool do_local_cprop (rtx
, rtx
, int, rtx
*);
706 static bool adjust_libcall_notes (rtx
, rtx
, rtx
, rtx
*);
707 static void local_cprop_pass (int);
708 static bool is_too_expensive (const char *);
711 /* Entry point for global common subexpression elimination.
712 F is the first instruction in the function. */
715 gcse_main (rtx f
, FILE *file
)
718 /* Bytes used at start of pass. */
719 int initial_bytes_used
;
720 /* Maximum number of bytes used by a pass. */
722 /* Point to release obstack data from for each pass. */
723 char *gcse_obstack_bottom
;
725 /* We do not construct an accurate cfg in functions which call
726 setjmp, so just punt to be safe. */
727 if (current_function_calls_setjmp
)
730 /* Assume that we do not need to run jump optimizations after gcse. */
731 run_jump_opt_after_gcse
= 0;
733 /* For calling dump_foo fns from gdb. */
734 debug_stderr
= stderr
;
737 /* Identify the basic block information for this function, including
738 successors and predecessors. */
739 max_gcse_regno
= max_reg_num ();
742 dump_flow_info (file
);
744 /* Return if there's nothing to do, or it is too expensive. */
745 if (n_basic_blocks
<= 1 || is_too_expensive (_("GCSE disabled")))
748 gcc_obstack_init (&gcse_obstack
);
752 init_alias_analysis ();
753 /* Record where pseudo-registers are set. This data is kept accurate
754 during each pass. ??? We could also record hard-reg information here
755 [since it's unchanging], however it is currently done during hash table
758 It may be tempting to compute MEM set information here too, but MEM sets
759 will be subject to code motion one day and thus we need to compute
760 information about memory sets when we build the hash tables. */
762 alloc_reg_set_mem (max_gcse_regno
);
766 initial_bytes_used
= bytes_used
;
768 gcse_obstack_bottom
= gcse_alloc (1);
770 while (changed
&& pass
< MAX_GCSE_PASSES
)
774 fprintf (file
, "GCSE pass %d\n\n", pass
+ 1);
776 /* Initialize bytes_used to the space for the pred/succ lists,
777 and the reg_set_table data. */
778 bytes_used
= initial_bytes_used
;
780 /* Each pass may create new registers, so recalculate each time. */
781 max_gcse_regno
= max_reg_num ();
785 /* Don't allow constant propagation to modify jumps
787 changed
= one_cprop_pass (pass
+ 1, 0, 0);
790 changed
|= one_classic_gcse_pass (pass
+ 1);
793 changed
|= one_pre_gcse_pass (pass
+ 1);
794 /* We may have just created new basic blocks. Release and
795 recompute various things which are sized on the number of
799 free_modify_mem_tables ();
800 modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
801 canon_modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
804 alloc_reg_set_mem (max_reg_num ());
806 run_jump_opt_after_gcse
= 1;
809 if (max_pass_bytes
< bytes_used
)
810 max_pass_bytes
= bytes_used
;
812 /* Free up memory, then reallocate for code hoisting. We can
813 not re-use the existing allocated memory because the tables
814 will not have info for the insns or registers created by
815 partial redundancy elimination. */
818 /* It does not make sense to run code hoisting unless we optimizing
819 for code size -- it rarely makes programs faster, and can make
820 them bigger if we did partial redundancy elimination (when optimizing
821 for space, we use a classic gcse algorithm instead of partial
822 redundancy algorithms). */
825 max_gcse_regno
= max_reg_num ();
827 changed
|= one_code_hoisting_pass ();
830 if (max_pass_bytes
< bytes_used
)
831 max_pass_bytes
= bytes_used
;
836 fprintf (file
, "\n");
840 obstack_free (&gcse_obstack
, gcse_obstack_bottom
);
844 /* Do one last pass of copy propagation, including cprop into
845 conditional jumps. */
847 max_gcse_regno
= max_reg_num ();
849 /* This time, go ahead and allow cprop to alter jumps. */
850 one_cprop_pass (pass
+ 1, 1, 0);
855 fprintf (file
, "GCSE of %s: %d basic blocks, ",
856 current_function_name
, n_basic_blocks
);
857 fprintf (file
, "%d pass%s, %d bytes\n\n",
858 pass
, pass
> 1 ? "es" : "", max_pass_bytes
);
861 obstack_free (&gcse_obstack
, NULL
);
863 /* We are finished with alias. */
864 end_alias_analysis ();
865 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
867 if (!optimize_size
&& flag_gcse_sm
)
870 /* Record where pseudo-registers are set. */
871 return run_jump_opt_after_gcse
;
874 /* Misc. utilities. */
876 /* Nonzero for each mode that supports (set (reg) (reg)).
877 This is trivially true for integer and floating point values.
878 It may or may not be true for condition codes. */
879 static char can_copy
[(int) NUM_MACHINE_MODES
];
881 /* Compute which modes support reg/reg copy operations. */
884 compute_can_copy (void)
887 #ifndef AVOID_CCMODE_COPIES
890 memset (can_copy
, 0, NUM_MACHINE_MODES
);
893 for (i
= 0; i
< NUM_MACHINE_MODES
; i
++)
894 if (GET_MODE_CLASS (i
) == MODE_CC
)
896 #ifdef AVOID_CCMODE_COPIES
899 reg
= gen_rtx_REG ((enum machine_mode
) i
, LAST_VIRTUAL_REGISTER
+ 1);
900 insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, reg
));
901 if (recog (PATTERN (insn
), insn
, NULL
) >= 0)
911 /* Returns whether the mode supports reg/reg copy operations. */
914 can_copy_p (enum machine_mode mode
)
916 static bool can_copy_init_p
= false;
918 if (! can_copy_init_p
)
921 can_copy_init_p
= true;
924 return can_copy
[mode
] != 0;
927 /* Cover function to xmalloc to record bytes allocated. */
930 gmalloc (size_t size
)
933 return xmalloc (size
);
936 /* Cover function to xcalloc to record bytes allocated. */
939 gcalloc (size_t nelem
, size_t elsize
)
941 bytes_used
+= nelem
* elsize
;
942 return xcalloc (nelem
, elsize
);
945 /* Cover function to xrealloc.
946 We don't record the additional size since we don't know it.
947 It won't affect memory usage stats much anyway. */
950 grealloc (void *ptr
, size_t size
)
952 return xrealloc (ptr
, size
);
955 /* Cover function to obstack_alloc. */
958 gcse_alloc (unsigned long size
)
961 return obstack_alloc (&gcse_obstack
, size
);
964 /* Allocate memory for the cuid mapping array,
965 and reg/memory set tracking tables.
967 This is called at the start of each pass. */
970 alloc_gcse_mem (rtx f
)
975 /* Find the largest UID and create a mapping from UIDs to CUIDs.
976 CUIDs are like UIDs except they increase monotonically, have no gaps,
977 and only apply to real insns. */
979 max_uid
= get_max_uid ();
980 uid_cuid
= gcalloc (max_uid
+ 1, sizeof (int));
981 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
984 uid_cuid
[INSN_UID (insn
)] = i
++;
986 uid_cuid
[INSN_UID (insn
)] = i
;
989 /* Create a table mapping cuids to insns. */
992 cuid_insn
= gcalloc (max_cuid
+ 1, sizeof (rtx
));
993 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
995 CUID_INSN (i
++) = insn
;
997 /* Allocate vars to track sets of regs. */
998 reg_set_bitmap
= BITMAP_XMALLOC ();
1000 /* Allocate vars to track sets of regs, memory per block. */
1001 reg_set_in_block
= sbitmap_vector_alloc (last_basic_block
, max_gcse_regno
);
1002 /* Allocate array to keep a list of insns which modify memory in each
1004 modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
1005 canon_modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
1006 modify_mem_list_set
= BITMAP_XMALLOC ();
1007 canon_modify_mem_list_set
= BITMAP_XMALLOC ();
1010 /* Free memory allocated by alloc_gcse_mem. */
1013 free_gcse_mem (void)
1018 BITMAP_XFREE (reg_set_bitmap
);
1020 sbitmap_vector_free (reg_set_in_block
);
1021 free_modify_mem_tables ();
1022 BITMAP_XFREE (modify_mem_list_set
);
1023 BITMAP_XFREE (canon_modify_mem_list_set
);
1026 /* Many of the global optimization algorithms work by solving dataflow
1027 equations for various expressions. Initially, some local value is
1028 computed for each expression in each block. Then, the values across the
1029 various blocks are combined (by following flow graph edges) to arrive at
1030 global values. Conceptually, each set of equations is independent. We
1031 may therefore solve all the equations in parallel, solve them one at a
1032 time, or pick any intermediate approach.
1034 When you're going to need N two-dimensional bitmaps, each X (say, the
1035 number of blocks) by Y (say, the number of expressions), call this
1036 function. It's not important what X and Y represent; only that Y
1037 correspond to the things that can be done in parallel. This function will
1038 return an appropriate chunking factor C; you should solve C sets of
1039 equations in parallel. By going through this function, we can easily
1040 trade space against time; by solving fewer equations in parallel we use
1044 get_bitmap_width (int n
, int x
, int y
)
1046 /* It's not really worth figuring out *exactly* how much memory will
1047 be used by a particular choice. The important thing is to get
1048 something approximately right. */
1049 size_t max_bitmap_memory
= 10 * 1024 * 1024;
1051 /* The number of bytes we'd use for a single column of minimum
1053 size_t column_size
= n
* x
* sizeof (SBITMAP_ELT_TYPE
);
1055 /* Often, it's reasonable just to solve all the equations in
1057 if (column_size
* SBITMAP_SET_SIZE (y
) <= max_bitmap_memory
)
1060 /* Otherwise, pick the largest width we can, without going over the
1062 return SBITMAP_ELT_BITS
* ((max_bitmap_memory
+ column_size
- 1)
1066 /* Compute the local properties of each recorded expression.
1068 Local properties are those that are defined by the block, irrespective of
1071 An expression is transparent in a block if its operands are not modified
1074 An expression is computed (locally available) in a block if it is computed
1075 at least once and expression would contain the same value if the
1076 computation was moved to the end of the block.
1078 An expression is locally anticipatable in a block if it is computed at
1079 least once and expression would contain the same value if the computation
1080 was moved to the beginning of the block.
1082 We call this routine for cprop, pre and code hoisting. They all compute
1083 basically the same information and thus can easily share this code.
1085 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1086 properties. If NULL, then it is not necessary to compute or record that
1087 particular property.
1089 TABLE controls which hash table to look at. If it is set hash table,
1090 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1094 compute_local_properties (sbitmap
*transp
, sbitmap
*comp
, sbitmap
*antloc
, struct hash_table
*table
)
1098 /* Initialize any bitmaps that were passed in. */
1102 sbitmap_vector_zero (transp
, last_basic_block
);
1104 sbitmap_vector_ones (transp
, last_basic_block
);
1108 sbitmap_vector_zero (comp
, last_basic_block
);
1110 sbitmap_vector_zero (antloc
, last_basic_block
);
1112 for (i
= 0; i
< table
->size
; i
++)
1116 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1118 int indx
= expr
->bitmap_index
;
1121 /* The expression is transparent in this block if it is not killed.
1122 We start by assuming all are transparent [none are killed], and
1123 then reset the bits for those that are. */
1125 compute_transp (expr
->expr
, indx
, transp
, table
->set_p
);
1127 /* The occurrences recorded in antic_occr are exactly those that
1128 we want to set to nonzero in ANTLOC. */
1130 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
1132 SET_BIT (antloc
[BLOCK_NUM (occr
->insn
)], indx
);
1134 /* While we're scanning the table, this is a good place to
1136 occr
->deleted_p
= 0;
1139 /* The occurrences recorded in avail_occr are exactly those that
1140 we want to set to nonzero in COMP. */
1142 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
1144 SET_BIT (comp
[BLOCK_NUM (occr
->insn
)], indx
);
1146 /* While we're scanning the table, this is a good place to
1151 /* While we're scanning the table, this is a good place to
1153 expr
->reaching_reg
= 0;
1158 /* Register set information.
1160 `reg_set_table' records where each register is set or otherwise
1163 static struct obstack reg_set_obstack
;
1166 alloc_reg_set_mem (int n_regs
)
1168 reg_set_table_size
= n_regs
+ REG_SET_TABLE_SLOP
;
1169 reg_set_table
= gcalloc (reg_set_table_size
, sizeof (struct reg_set
*));
1171 gcc_obstack_init (®_set_obstack
);
1175 free_reg_set_mem (void)
1177 free (reg_set_table
);
1178 obstack_free (®_set_obstack
, NULL
);
1181 /* An OLD_INSN that used to set REGNO was replaced by NEW_INSN.
1182 Update the corresponding `reg_set_table' entry accordingly.
1183 We assume that NEW_INSN is not already recorded in reg_set_table[regno]. */
1186 replace_one_set (int regno
, rtx old_insn
, rtx new_insn
)
1188 struct reg_set
*reg_info
;
1189 if (regno
>= reg_set_table_size
)
1191 for (reg_info
= reg_set_table
[regno
]; reg_info
; reg_info
= reg_info
->next
)
1192 if (reg_info
->insn
== old_insn
)
1194 reg_info
->insn
= new_insn
;
1199 /* Record REGNO in the reg_set table. */
1202 record_one_set (int regno
, rtx insn
)
1204 /* Allocate a new reg_set element and link it onto the list. */
1205 struct reg_set
*new_reg_info
;
1207 /* If the table isn't big enough, enlarge it. */
1208 if (regno
>= reg_set_table_size
)
1210 int new_size
= regno
+ REG_SET_TABLE_SLOP
;
1212 reg_set_table
= grealloc (reg_set_table
,
1213 new_size
* sizeof (struct reg_set
*));
1214 memset (reg_set_table
+ reg_set_table_size
, 0,
1215 (new_size
- reg_set_table_size
) * sizeof (struct reg_set
*));
1216 reg_set_table_size
= new_size
;
1219 new_reg_info
= obstack_alloc (®_set_obstack
, sizeof (struct reg_set
));
1220 bytes_used
+= sizeof (struct reg_set
);
1221 new_reg_info
->insn
= insn
;
1222 new_reg_info
->next
= reg_set_table
[regno
];
1223 reg_set_table
[regno
] = new_reg_info
;
1226 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1227 an insn. The DATA is really the instruction in which the SET is
1231 record_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
, void *data
)
1233 rtx record_set_insn
= (rtx
) data
;
1235 if (GET_CODE (dest
) == REG
&& REGNO (dest
) >= FIRST_PSEUDO_REGISTER
)
1236 record_one_set (REGNO (dest
), record_set_insn
);
1239 /* Scan the function and record each set of each pseudo-register.
1241 This is called once, at the start of the gcse pass. See the comments for
1242 `reg_set_table' for further documentation. */
1245 compute_sets (rtx f
)
1249 for (insn
= f
; insn
!= 0; insn
= NEXT_INSN (insn
))
1251 note_stores (PATTERN (insn
), record_set_info
, insn
);
1254 /* Hash table support. */
1256 struct reg_avail_info
1258 basic_block last_bb
;
1263 static struct reg_avail_info
*reg_avail_info
;
1264 static basic_block current_bb
;
1267 /* See whether X, the source of a set, is something we want to consider for
1270 static GTY(()) rtx test_insn
;
1272 want_to_gcse_p (rtx x
)
1274 int num_clobbers
= 0;
1277 switch (GET_CODE (x
))
1285 case CONSTANT_P_RTX
:
1292 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1293 if (general_operand (x
, GET_MODE (x
)))
1295 else if (GET_MODE (x
) == VOIDmode
)
1298 /* Otherwise, check if we can make a valid insn from it. First initialize
1299 our test insn if we haven't already. */
1303 = make_insn_raw (gen_rtx_SET (VOIDmode
,
1304 gen_rtx_REG (word_mode
,
1305 FIRST_PSEUDO_REGISTER
* 2),
1307 NEXT_INSN (test_insn
) = PREV_INSN (test_insn
) = 0;
1310 /* Now make an insn like the one we would make when GCSE'ing and see if
1312 PUT_MODE (SET_DEST (PATTERN (test_insn
)), GET_MODE (x
));
1313 SET_SRC (PATTERN (test_insn
)) = x
;
1314 return ((icode
= recog (PATTERN (test_insn
), test_insn
, &num_clobbers
)) >= 0
1315 && (num_clobbers
== 0 || ! added_clobbers_hard_reg_p (icode
)));
1318 /* Return nonzero if the operands of expression X are unchanged from the
1319 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1320 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1323 oprs_unchanged_p (rtx x
, rtx insn
, int avail_p
)
1332 code
= GET_CODE (x
);
1337 struct reg_avail_info
*info
= ®_avail_info
[REGNO (x
)];
1339 if (info
->last_bb
!= current_bb
)
1342 return info
->last_set
< INSN_CUID (insn
);
1344 return info
->first_set
>= INSN_CUID (insn
);
1348 if (load_killed_in_block_p (current_bb
, INSN_CUID (insn
),
1352 return oprs_unchanged_p (XEXP (x
, 0), insn
, avail_p
);
1378 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1382 /* If we are about to do the last recursive call needed at this
1383 level, change it into iteration. This function is called enough
1386 return oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
);
1388 else if (! oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
))
1391 else if (fmt
[i
] == 'E')
1392 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1393 if (! oprs_unchanged_p (XVECEXP (x
, i
, j
), insn
, avail_p
))
1400 /* Used for communication between mems_conflict_for_gcse_p and
1401 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1402 conflict between two memory references. */
1403 static int gcse_mems_conflict_p
;
1405 /* Used for communication between mems_conflict_for_gcse_p and
1406 load_killed_in_block_p. A memory reference for a load instruction,
1407 mems_conflict_for_gcse_p will see if a memory store conflicts with
1408 this memory load. */
1409 static rtx gcse_mem_operand
;
1411 /* DEST is the output of an instruction. If it is a memory reference, and
1412 possibly conflicts with the load found in gcse_mem_operand, then set
1413 gcse_mems_conflict_p to a nonzero value. */
1416 mems_conflict_for_gcse_p (rtx dest
, rtx setter ATTRIBUTE_UNUSED
,
1417 void *data ATTRIBUTE_UNUSED
)
1419 while (GET_CODE (dest
) == SUBREG
1420 || GET_CODE (dest
) == ZERO_EXTRACT
1421 || GET_CODE (dest
) == SIGN_EXTRACT
1422 || GET_CODE (dest
) == STRICT_LOW_PART
)
1423 dest
= XEXP (dest
, 0);
1425 /* If DEST is not a MEM, then it will not conflict with the load. Note
1426 that function calls are assumed to clobber memory, but are handled
1428 if (GET_CODE (dest
) != MEM
)
1431 /* If we are setting a MEM in our list of specially recognized MEMs,
1432 don't mark as killed this time. */
1434 if (expr_equiv_p (dest
, gcse_mem_operand
) && pre_ldst_mems
!= NULL
)
1436 if (!find_rtx_in_ldst (dest
))
1437 gcse_mems_conflict_p
= 1;
1441 if (true_dependence (dest
, GET_MODE (dest
), gcse_mem_operand
,
1443 gcse_mems_conflict_p
= 1;
1446 /* Return nonzero if the expression in X (a memory reference) is killed
1447 in block BB before or after the insn with the CUID in UID_LIMIT.
1448 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1451 To check the entire block, set UID_LIMIT to max_uid + 1 and
1455 load_killed_in_block_p (basic_block bb
, int uid_limit
, rtx x
, int avail_p
)
1457 rtx list_entry
= modify_mem_list
[bb
->index
];
1461 /* Ignore entries in the list that do not apply. */
1463 && INSN_CUID (XEXP (list_entry
, 0)) < uid_limit
)
1465 && INSN_CUID (XEXP (list_entry
, 0)) > uid_limit
))
1467 list_entry
= XEXP (list_entry
, 1);
1471 setter
= XEXP (list_entry
, 0);
1473 /* If SETTER is a call everything is clobbered. Note that calls
1474 to pure functions are never put on the list, so we need not
1475 worry about them. */
1476 if (GET_CODE (setter
) == CALL_INSN
)
1479 /* SETTER must be an INSN of some kind that sets memory. Call
1480 note_stores to examine each hunk of memory that is modified.
1482 The note_stores interface is pretty limited, so we have to
1483 communicate via global variables. Yuk. */
1484 gcse_mem_operand
= x
;
1485 gcse_mems_conflict_p
= 0;
1486 note_stores (PATTERN (setter
), mems_conflict_for_gcse_p
, NULL
);
1487 if (gcse_mems_conflict_p
)
1489 list_entry
= XEXP (list_entry
, 1);
1494 /* Return nonzero if the operands of expression X are unchanged from
1495 the start of INSN's basic block up to but not including INSN. */
1498 oprs_anticipatable_p (rtx x
, rtx insn
)
1500 return oprs_unchanged_p (x
, insn
, 0);
1503 /* Return nonzero if the operands of expression X are unchanged from
1504 INSN to the end of INSN's basic block. */
1507 oprs_available_p (rtx x
, rtx insn
)
1509 return oprs_unchanged_p (x
, insn
, 1);
1512 /* Hash expression X.
1514 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1515 indicating if a volatile operand is found or if the expression contains
1516 something we don't want to insert in the table.
1518 ??? One might want to merge this with canon_hash. Later. */
1521 hash_expr (rtx x
, enum machine_mode mode
, int *do_not_record_p
, int hash_table_size
)
1525 *do_not_record_p
= 0;
1527 hash
= hash_expr_1 (x
, mode
, do_not_record_p
);
1528 return hash
% hash_table_size
;
1531 /* Hash a string. Just add its bytes up. */
1533 static inline unsigned
1534 hash_string_1 (const char *ps
)
1537 const unsigned char *p
= (const unsigned char *) ps
;
1546 /* Subroutine of hash_expr to do the actual work. */
1549 hash_expr_1 (rtx x
, enum machine_mode mode
, int *do_not_record_p
)
1556 /* Used to turn recursion into iteration. We can't rely on GCC's
1557 tail-recursion elimination since we need to keep accumulating values
1564 code
= GET_CODE (x
);
1568 hash
+= ((unsigned int) REG
<< 7) + REGNO (x
);
1572 hash
+= (((unsigned int) CONST_INT
<< 7) + (unsigned int) mode
1573 + (unsigned int) INTVAL (x
));
1577 /* This is like the general case, except that it only counts
1578 the integers representing the constant. */
1579 hash
+= (unsigned int) code
+ (unsigned int) GET_MODE (x
);
1580 if (GET_MODE (x
) != VOIDmode
)
1581 for (i
= 2; i
< GET_RTX_LENGTH (CONST_DOUBLE
); i
++)
1582 hash
+= (unsigned int) XWINT (x
, i
);
1584 hash
+= ((unsigned int) CONST_DOUBLE_LOW (x
)
1585 + (unsigned int) CONST_DOUBLE_HIGH (x
));
1593 units
= CONST_VECTOR_NUNITS (x
);
1595 for (i
= 0; i
< units
; ++i
)
1597 elt
= CONST_VECTOR_ELT (x
, i
);
1598 hash
+= hash_expr_1 (elt
, GET_MODE (elt
), do_not_record_p
);
1604 /* Assume there is only one rtx object for any given label. */
1606 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1607 differences and differences between each stage's debugging dumps. */
1608 hash
+= (((unsigned int) LABEL_REF
<< 7)
1609 + CODE_LABEL_NUMBER (XEXP (x
, 0)));
1614 /* Don't hash on the symbol's address to avoid bootstrap differences.
1615 Different hash values may cause expressions to be recorded in
1616 different orders and thus different registers to be used in the
1617 final assembler. This also avoids differences in the dump files
1618 between various stages. */
1620 const unsigned char *p
= (const unsigned char *) XSTR (x
, 0);
1623 h
+= (h
<< 7) + *p
++; /* ??? revisit */
1625 hash
+= ((unsigned int) SYMBOL_REF
<< 7) + h
;
1630 if (MEM_VOLATILE_P (x
))
1632 *do_not_record_p
= 1;
1636 hash
+= (unsigned int) MEM
;
1637 /* We used alias set for hashing, but this is not good, since the alias
1638 set may differ in -fprofile-arcs and -fbranch-probabilities compilation
1639 causing the profiles to fail to match. */
1650 case UNSPEC_VOLATILE
:
1651 *do_not_record_p
= 1;
1655 if (MEM_VOLATILE_P (x
))
1657 *do_not_record_p
= 1;
1662 /* We don't want to take the filename and line into account. */
1663 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
)
1664 + hash_string_1 (ASM_OPERANDS_TEMPLATE (x
))
1665 + hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
))
1666 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x
);
1668 if (ASM_OPERANDS_INPUT_LENGTH (x
))
1670 for (i
= 1; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
1672 hash
+= (hash_expr_1 (ASM_OPERANDS_INPUT (x
, i
),
1673 GET_MODE (ASM_OPERANDS_INPUT (x
, i
)),
1675 + hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT
1679 hash
+= hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x
, 0));
1680 x
= ASM_OPERANDS_INPUT (x
, 0);
1681 mode
= GET_MODE (x
);
1691 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
);
1692 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1696 /* If we are about to do the last recursive call
1697 needed at this level, change it into iteration.
1698 This function is called enough to be worth it. */
1705 hash
+= hash_expr_1 (XEXP (x
, i
), 0, do_not_record_p
);
1706 if (*do_not_record_p
)
1710 else if (fmt
[i
] == 'E')
1711 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1713 hash
+= hash_expr_1 (XVECEXP (x
, i
, j
), 0, do_not_record_p
);
1714 if (*do_not_record_p
)
1718 else if (fmt
[i
] == 's')
1719 hash
+= hash_string_1 (XSTR (x
, i
));
1720 else if (fmt
[i
] == 'i')
1721 hash
+= (unsigned int) XINT (x
, i
);
1729 /* Hash a set of register REGNO.
1731 Sets are hashed on the register that is set. This simplifies the PRE copy
1734 ??? May need to make things more elaborate. Later, as necessary. */
1737 hash_set (int regno
, int hash_table_size
)
1742 return hash
% hash_table_size
;
1745 /* Return nonzero if exp1 is equivalent to exp2.
1746 ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
1749 expr_equiv_p (rtx x
, rtx y
)
1758 if (x
== 0 || y
== 0)
1761 code
= GET_CODE (x
);
1762 if (code
!= GET_CODE (y
))
1765 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
1766 if (GET_MODE (x
) != GET_MODE (y
))
1777 return XEXP (x
, 0) == XEXP (y
, 0);
1780 return XSTR (x
, 0) == XSTR (y
, 0);
1783 return REGNO (x
) == REGNO (y
);
1786 /* Can't merge two expressions in different alias sets, since we can
1787 decide that the expression is transparent in a block when it isn't,
1788 due to it being set with the different alias set. */
1789 if (MEM_ALIAS_SET (x
) != MEM_ALIAS_SET (y
))
1792 /* A volatile mem should not be considered equivalent to any other. */
1793 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
1797 /* For commutative operations, check both orders. */
1805 return ((expr_equiv_p (XEXP (x
, 0), XEXP (y
, 0))
1806 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 1)))
1807 || (expr_equiv_p (XEXP (x
, 0), XEXP (y
, 1))
1808 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 0))));
1811 /* We don't use the generic code below because we want to
1812 disregard filename and line numbers. */
1814 /* A volatile asm isn't equivalent to any other. */
1815 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
1818 if (GET_MODE (x
) != GET_MODE (y
)
1819 || strcmp (ASM_OPERANDS_TEMPLATE (x
), ASM_OPERANDS_TEMPLATE (y
))
1820 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
),
1821 ASM_OPERANDS_OUTPUT_CONSTRAINT (y
))
1822 || ASM_OPERANDS_OUTPUT_IDX (x
) != ASM_OPERANDS_OUTPUT_IDX (y
)
1823 || ASM_OPERANDS_INPUT_LENGTH (x
) != ASM_OPERANDS_INPUT_LENGTH (y
))
1826 if (ASM_OPERANDS_INPUT_LENGTH (x
))
1828 for (i
= ASM_OPERANDS_INPUT_LENGTH (x
) - 1; i
>= 0; i
--)
1829 if (! expr_equiv_p (ASM_OPERANDS_INPUT (x
, i
),
1830 ASM_OPERANDS_INPUT (y
, i
))
1831 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x
, i
),
1832 ASM_OPERANDS_INPUT_CONSTRAINT (y
, i
)))
1842 /* Compare the elements. If any pair of corresponding elements
1843 fail to match, return 0 for the whole thing. */
1845 fmt
= GET_RTX_FORMAT (code
);
1846 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1851 if (! expr_equiv_p (XEXP (x
, i
), XEXP (y
, i
)))
1856 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1858 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1859 if (! expr_equiv_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
1864 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1869 if (XINT (x
, i
) != XINT (y
, i
))
1874 if (XWINT (x
, i
) != XWINT (y
, i
))
1889 /* Insert expression X in INSN in the hash TABLE.
1890 If it is already present, record it as the last occurrence in INSN's
1893 MODE is the mode of the value X is being stored into.
1894 It is only used if X is a CONST_INT.
1896 ANTIC_P is nonzero if X is an anticipatable expression.
1897 AVAIL_P is nonzero if X is an available expression. */
1900 insert_expr_in_table (rtx x
, enum machine_mode mode
, rtx insn
, int antic_p
,
1901 int avail_p
, struct hash_table
*table
)
1903 int found
, do_not_record_p
;
1905 struct expr
*cur_expr
, *last_expr
= NULL
;
1906 struct occr
*antic_occr
, *avail_occr
;
1907 struct occr
*last_occr
= NULL
;
1909 hash
= hash_expr (x
, mode
, &do_not_record_p
, table
->size
);
1911 /* Do not insert expression in table if it contains volatile operands,
1912 or if hash_expr determines the expression is something we don't want
1913 to or can't handle. */
1914 if (do_not_record_p
)
1917 cur_expr
= table
->table
[hash
];
1920 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1922 /* If the expression isn't found, save a pointer to the end of
1924 last_expr
= cur_expr
;
1925 cur_expr
= cur_expr
->next_same_hash
;
1930 cur_expr
= gcse_alloc (sizeof (struct expr
));
1931 bytes_used
+= sizeof (struct expr
);
1932 if (table
->table
[hash
] == NULL
)
1933 /* This is the first pattern that hashed to this index. */
1934 table
->table
[hash
] = cur_expr
;
1936 /* Add EXPR to end of this hash chain. */
1937 last_expr
->next_same_hash
= cur_expr
;
1939 /* Set the fields of the expr element. */
1941 cur_expr
->bitmap_index
= table
->n_elems
++;
1942 cur_expr
->next_same_hash
= NULL
;
1943 cur_expr
->antic_occr
= NULL
;
1944 cur_expr
->avail_occr
= NULL
;
1947 /* Now record the occurrence(s). */
1950 antic_occr
= cur_expr
->antic_occr
;
1952 /* Search for another occurrence in the same basic block. */
1953 while (antic_occr
&& BLOCK_NUM (antic_occr
->insn
) != BLOCK_NUM (insn
))
1955 /* If an occurrence isn't found, save a pointer to the end of
1957 last_occr
= antic_occr
;
1958 antic_occr
= antic_occr
->next
;
1962 /* Found another instance of the expression in the same basic block.
1963 Prefer the currently recorded one. We want the first one in the
1964 block and the block is scanned from start to end. */
1965 ; /* nothing to do */
1968 /* First occurrence of this expression in this basic block. */
1969 antic_occr
= gcse_alloc (sizeof (struct occr
));
1970 bytes_used
+= sizeof (struct occr
);
1971 /* First occurrence of this expression in any block? */
1972 if (cur_expr
->antic_occr
== NULL
)
1973 cur_expr
->antic_occr
= antic_occr
;
1975 last_occr
->next
= antic_occr
;
1977 antic_occr
->insn
= insn
;
1978 antic_occr
->next
= NULL
;
1984 avail_occr
= cur_expr
->avail_occr
;
1986 /* Search for another occurrence in the same basic block. */
1987 while (avail_occr
&& BLOCK_NUM (avail_occr
->insn
) != BLOCK_NUM (insn
))
1989 /* If an occurrence isn't found, save a pointer to the end of
1991 last_occr
= avail_occr
;
1992 avail_occr
= avail_occr
->next
;
1996 /* Found another instance of the expression in the same basic block.
1997 Prefer this occurrence to the currently recorded one. We want
1998 the last one in the block and the block is scanned from start
2000 avail_occr
->insn
= insn
;
2003 /* First occurrence of this expression in this basic block. */
2004 avail_occr
= gcse_alloc (sizeof (struct occr
));
2005 bytes_used
+= sizeof (struct occr
);
2007 /* First occurrence of this expression in any block? */
2008 if (cur_expr
->avail_occr
== NULL
)
2009 cur_expr
->avail_occr
= avail_occr
;
2011 last_occr
->next
= avail_occr
;
2013 avail_occr
->insn
= insn
;
2014 avail_occr
->next
= NULL
;
2019 /* Insert pattern X in INSN in the hash table.
2020 X is a SET of a reg to either another reg or a constant.
2021 If it is already present, record it as the last occurrence in INSN's
2025 insert_set_in_table (rtx x
, rtx insn
, struct hash_table
*table
)
2029 struct expr
*cur_expr
, *last_expr
= NULL
;
2030 struct occr
*cur_occr
, *last_occr
= NULL
;
2032 if (GET_CODE (x
) != SET
2033 || GET_CODE (SET_DEST (x
)) != REG
)
2036 hash
= hash_set (REGNO (SET_DEST (x
)), table
->size
);
2038 cur_expr
= table
->table
[hash
];
2041 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
2043 /* If the expression isn't found, save a pointer to the end of
2045 last_expr
= cur_expr
;
2046 cur_expr
= cur_expr
->next_same_hash
;
2051 cur_expr
= gcse_alloc (sizeof (struct expr
));
2052 bytes_used
+= sizeof (struct expr
);
2053 if (table
->table
[hash
] == NULL
)
2054 /* This is the first pattern that hashed to this index. */
2055 table
->table
[hash
] = cur_expr
;
2057 /* Add EXPR to end of this hash chain. */
2058 last_expr
->next_same_hash
= cur_expr
;
2060 /* Set the fields of the expr element.
2061 We must copy X because it can be modified when copy propagation is
2062 performed on its operands. */
2063 cur_expr
->expr
= copy_rtx (x
);
2064 cur_expr
->bitmap_index
= table
->n_elems
++;
2065 cur_expr
->next_same_hash
= NULL
;
2066 cur_expr
->antic_occr
= NULL
;
2067 cur_expr
->avail_occr
= NULL
;
2070 /* Now record the occurrence. */
2071 cur_occr
= cur_expr
->avail_occr
;
2073 /* Search for another occurrence in the same basic block. */
2074 while (cur_occr
&& BLOCK_NUM (cur_occr
->insn
) != BLOCK_NUM (insn
))
2076 /* If an occurrence isn't found, save a pointer to the end of
2078 last_occr
= cur_occr
;
2079 cur_occr
= cur_occr
->next
;
2083 /* Found another instance of the expression in the same basic block.
2084 Prefer this occurrence to the currently recorded one. We want the
2085 last one in the block and the block is scanned from start to end. */
2086 cur_occr
->insn
= insn
;
2089 /* First occurrence of this expression in this basic block. */
2090 cur_occr
= gcse_alloc (sizeof (struct occr
));
2091 bytes_used
+= sizeof (struct occr
);
2093 /* First occurrence of this expression in any block? */
2094 if (cur_expr
->avail_occr
== NULL
)
2095 cur_expr
->avail_occr
= cur_occr
;
2097 last_occr
->next
= cur_occr
;
2099 cur_occr
->insn
= insn
;
2100 cur_occr
->next
= NULL
;
2104 /* Determine whether the rtx X should be treated as a constant for
2105 the purposes of GCSE's constant propagation. */
2108 gcse_constant_p (rtx x
)
2110 /* Consider a COMPARE of two integers constant. */
2111 if (GET_CODE (x
) == COMPARE
2112 && GET_CODE (XEXP (x
, 0)) == CONST_INT
2113 && GET_CODE (XEXP (x
, 1)) == CONST_INT
)
2117 /* Consider a COMPARE of the same registers is a constant
2118 if they are not floating point registers. */
2119 if (GET_CODE(x
) == COMPARE
2120 && GET_CODE (XEXP (x
, 0)) == REG
2121 && GET_CODE (XEXP (x
, 1)) == REG
2122 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (x
, 1))
2123 && ! FLOAT_MODE_P (GET_MODE (XEXP (x
, 0)))
2124 && ! FLOAT_MODE_P (GET_MODE (XEXP (x
, 1))))
2127 if (GET_CODE (x
) == CONSTANT_P_RTX
)
2130 return CONSTANT_P (x
);
2133 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
2137 hash_scan_set (rtx pat
, rtx insn
, struct hash_table
*table
)
2139 rtx src
= SET_SRC (pat
);
2140 rtx dest
= SET_DEST (pat
);
2143 if (GET_CODE (src
) == CALL
)
2144 hash_scan_call (src
, insn
, table
);
2146 else if (GET_CODE (dest
) == REG
)
2148 unsigned int regno
= REGNO (dest
);
2151 /* If this is a single set and we are doing constant propagation,
2152 see if a REG_NOTE shows this equivalent to a constant. */
2153 if (table
->set_p
&& (note
= find_reg_equal_equiv_note (insn
)) != 0
2154 && gcse_constant_p (XEXP (note
, 0)))
2155 src
= XEXP (note
, 0), pat
= gen_rtx_SET (VOIDmode
, dest
, src
);
2157 /* Only record sets of pseudo-regs in the hash table. */
2159 && regno
>= FIRST_PSEUDO_REGISTER
2160 /* Don't GCSE something if we can't do a reg/reg copy. */
2161 && can_copy_p (GET_MODE (dest
))
2162 /* GCSE commonly inserts instruction after the insn. We can't
2163 do that easily for EH_REGION notes so disable GCSE on these
2165 && !find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
2166 /* Is SET_SRC something we want to gcse? */
2167 && want_to_gcse_p (src
)
2168 /* Don't CSE a nop. */
2169 && ! set_noop_p (pat
)
2170 /* Don't GCSE if it has attached REG_EQUIV note.
2171 At this point this only function parameters should have
2172 REG_EQUIV notes and if the argument slot is used somewhere
2173 explicitly, it means address of parameter has been taken,
2174 so we should not extend the lifetime of the pseudo. */
2175 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
2176 || GET_CODE (XEXP (note
, 0)) != MEM
))
2178 /* An expression is not anticipatable if its operands are
2179 modified before this insn or if this is not the only SET in
2181 int antic_p
= oprs_anticipatable_p (src
, insn
) && single_set (insn
);
2182 /* An expression is not available if its operands are
2183 subsequently modified, including this insn. It's also not
2184 available if this is a branch, because we can't insert
2185 a set after the branch. */
2186 int avail_p
= (oprs_available_p (src
, insn
)
2187 && ! JUMP_P (insn
));
2189 insert_expr_in_table (src
, GET_MODE (dest
), insn
, antic_p
, avail_p
, table
);
2192 /* Record sets for constant/copy propagation. */
2193 else if (table
->set_p
2194 && regno
>= FIRST_PSEUDO_REGISTER
2195 && ((GET_CODE (src
) == REG
2196 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
2197 && can_copy_p (GET_MODE (dest
))
2198 && REGNO (src
) != regno
)
2199 || gcse_constant_p (src
))
2200 /* A copy is not available if its src or dest is subsequently
2201 modified. Here we want to search from INSN+1 on, but
2202 oprs_available_p searches from INSN on. */
2203 && (insn
== BLOCK_END (BLOCK_NUM (insn
))
2204 || ((tmp
= next_nonnote_insn (insn
)) != NULL_RTX
2205 && oprs_available_p (pat
, tmp
))))
2206 insert_set_in_table (pat
, insn
, table
);
2211 hash_scan_clobber (rtx x ATTRIBUTE_UNUSED
, rtx insn ATTRIBUTE_UNUSED
,
2212 struct hash_table
*table ATTRIBUTE_UNUSED
)
2214 /* Currently nothing to do. */
2218 hash_scan_call (rtx x ATTRIBUTE_UNUSED
, rtx insn ATTRIBUTE_UNUSED
,
2219 struct hash_table
*table ATTRIBUTE_UNUSED
)
2221 /* Currently nothing to do. */
2224 /* Process INSN and add hash table entries as appropriate.
2226 Only available expressions that set a single pseudo-reg are recorded.
2228 Single sets in a PARALLEL could be handled, but it's an extra complication
2229 that isn't dealt with right now. The trick is handling the CLOBBERs that
2230 are also in the PARALLEL. Later.
2232 If SET_P is nonzero, this is for the assignment hash table,
2233 otherwise it is for the expression hash table.
2234 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
2235 not record any expressions. */
2238 hash_scan_insn (rtx insn
, struct hash_table
*table
, int in_libcall_block
)
2240 rtx pat
= PATTERN (insn
);
2243 if (in_libcall_block
)
2246 /* Pick out the sets of INSN and for other forms of instructions record
2247 what's been modified. */
2249 if (GET_CODE (pat
) == SET
)
2250 hash_scan_set (pat
, insn
, table
);
2251 else if (GET_CODE (pat
) == PARALLEL
)
2252 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2254 rtx x
= XVECEXP (pat
, 0, i
);
2256 if (GET_CODE (x
) == SET
)
2257 hash_scan_set (x
, insn
, table
);
2258 else if (GET_CODE (x
) == CLOBBER
)
2259 hash_scan_clobber (x
, insn
, table
);
2260 else if (GET_CODE (x
) == CALL
)
2261 hash_scan_call (x
, insn
, table
);
2264 else if (GET_CODE (pat
) == CLOBBER
)
2265 hash_scan_clobber (pat
, insn
, table
);
2266 else if (GET_CODE (pat
) == CALL
)
2267 hash_scan_call (pat
, insn
, table
);
2271 dump_hash_table (FILE *file
, const char *name
, struct hash_table
*table
)
2274 /* Flattened out table, so it's printed in proper order. */
2275 struct expr
**flat_table
;
2276 unsigned int *hash_val
;
2279 flat_table
= xcalloc (table
->n_elems
, sizeof (struct expr
*));
2280 hash_val
= xmalloc (table
->n_elems
* sizeof (unsigned int));
2282 for (i
= 0; i
< (int) table
->size
; i
++)
2283 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
2285 flat_table
[expr
->bitmap_index
] = expr
;
2286 hash_val
[expr
->bitmap_index
] = i
;
2289 fprintf (file
, "%s hash table (%d buckets, %d entries)\n",
2290 name
, table
->size
, table
->n_elems
);
2292 for (i
= 0; i
< (int) table
->n_elems
; i
++)
2293 if (flat_table
[i
] != 0)
2295 expr
= flat_table
[i
];
2296 fprintf (file
, "Index %d (hash value %d)\n ",
2297 expr
->bitmap_index
, hash_val
[i
]);
2298 print_rtl (file
, expr
->expr
);
2299 fprintf (file
, "\n");
2302 fprintf (file
, "\n");
2308 /* Record register first/last/block set information for REGNO in INSN.
2310 first_set records the first place in the block where the register
2311 is set and is used to compute "anticipatability".
2313 last_set records the last place in the block where the register
2314 is set and is used to compute "availability".
2316 last_bb records the block for which first_set and last_set are
2317 valid, as a quick test to invalidate them.
2319 reg_set_in_block records whether the register is set in the block
2320 and is used to compute "transparency". */
2323 record_last_reg_set_info (rtx insn
, int regno
)
2325 struct reg_avail_info
*info
= ®_avail_info
[regno
];
2326 int cuid
= INSN_CUID (insn
);
2328 info
->last_set
= cuid
;
2329 if (info
->last_bb
!= current_bb
)
2331 info
->last_bb
= current_bb
;
2332 info
->first_set
= cuid
;
2333 SET_BIT (reg_set_in_block
[current_bb
->index
], regno
);
2338 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
2339 Note we store a pair of elements in the list, so they have to be
2340 taken off pairwise. */
2343 canon_list_insert (rtx dest ATTRIBUTE_UNUSED
, rtx unused1 ATTRIBUTE_UNUSED
,
2346 rtx dest_addr
, insn
;
2349 while (GET_CODE (dest
) == SUBREG
2350 || GET_CODE (dest
) == ZERO_EXTRACT
2351 || GET_CODE (dest
) == SIGN_EXTRACT
2352 || GET_CODE (dest
) == STRICT_LOW_PART
)
2353 dest
= XEXP (dest
, 0);
2355 /* If DEST is not a MEM, then it will not conflict with a load. Note
2356 that function calls are assumed to clobber memory, but are handled
2359 if (GET_CODE (dest
) != MEM
)
2362 dest_addr
= get_addr (XEXP (dest
, 0));
2363 dest_addr
= canon_rtx (dest_addr
);
2364 insn
= (rtx
) v_insn
;
2365 bb
= BLOCK_NUM (insn
);
2367 canon_modify_mem_list
[bb
] =
2368 alloc_EXPR_LIST (VOIDmode
, dest_addr
, canon_modify_mem_list
[bb
]);
2369 canon_modify_mem_list
[bb
] =
2370 alloc_EXPR_LIST (VOIDmode
, dest
, canon_modify_mem_list
[bb
]);
2371 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2374 /* Record memory modification information for INSN. We do not actually care
2375 about the memory location(s) that are set, or even how they are set (consider
2376 a CALL_INSN). We merely need to record which insns modify memory. */
2379 record_last_mem_set_info (rtx insn
)
2381 int bb
= BLOCK_NUM (insn
);
2383 /* load_killed_in_block_p will handle the case of calls clobbering
2385 modify_mem_list
[bb
] = alloc_INSN_LIST (insn
, modify_mem_list
[bb
]);
2386 bitmap_set_bit (modify_mem_list_set
, bb
);
2388 if (GET_CODE (insn
) == CALL_INSN
)
2390 /* Note that traversals of this loop (other than for free-ing)
2391 will break after encountering a CALL_INSN. So, there's no
2392 need to insert a pair of items, as canon_list_insert does. */
2393 canon_modify_mem_list
[bb
] =
2394 alloc_INSN_LIST (insn
, canon_modify_mem_list
[bb
]);
2395 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2398 note_stores (PATTERN (insn
), canon_list_insert
, (void*) insn
);
2401 /* Called from compute_hash_table via note_stores to handle one
2402 SET or CLOBBER in an insn. DATA is really the instruction in which
2403 the SET is taking place. */
2406 record_last_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
, void *data
)
2408 rtx last_set_insn
= (rtx
) data
;
2410 if (GET_CODE (dest
) == SUBREG
)
2411 dest
= SUBREG_REG (dest
);
2413 if (GET_CODE (dest
) == REG
)
2414 record_last_reg_set_info (last_set_insn
, REGNO (dest
));
2415 else if (GET_CODE (dest
) == MEM
2416 /* Ignore pushes, they clobber nothing. */
2417 && ! push_operand (dest
, GET_MODE (dest
)))
2418 record_last_mem_set_info (last_set_insn
);
2421 /* Top level function to create an expression or assignment hash table.
2423 Expression entries are placed in the hash table if
2424 - they are of the form (set (pseudo-reg) src),
2425 - src is something we want to perform GCSE on,
2426 - none of the operands are subsequently modified in the block
2428 Assignment entries are placed in the hash table if
2429 - they are of the form (set (pseudo-reg) src),
2430 - src is something we want to perform const/copy propagation on,
2431 - none of the operands or target are subsequently modified in the block
2433 Currently src must be a pseudo-reg or a const_int.
2435 TABLE is the table computed. */
2438 compute_hash_table_work (struct hash_table
*table
)
2442 /* While we compute the hash table we also compute a bit array of which
2443 registers are set in which blocks.
2444 ??? This isn't needed during const/copy propagation, but it's cheap to
2446 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
2448 /* re-Cache any INSN_LIST nodes we have allocated. */
2449 clear_modify_mem_tables ();
2450 /* Some working arrays used to track first and last set in each block. */
2451 reg_avail_info
= gmalloc (max_gcse_regno
* sizeof (struct reg_avail_info
));
2453 for (i
= 0; i
< max_gcse_regno
; ++i
)
2454 reg_avail_info
[i
].last_bb
= NULL
;
2456 FOR_EACH_BB (current_bb
)
2460 int in_libcall_block
;
2462 /* First pass over the instructions records information used to
2463 determine when registers and memory are first and last set.
2464 ??? hard-reg reg_set_in_block computation
2465 could be moved to compute_sets since they currently don't change. */
2467 for (insn
= current_bb
->head
;
2468 insn
&& insn
!= NEXT_INSN (current_bb
->end
);
2469 insn
= NEXT_INSN (insn
))
2471 if (! INSN_P (insn
))
2474 if (GET_CODE (insn
) == CALL_INSN
)
2476 bool clobbers_all
= false;
2477 #ifdef NON_SAVING_SETJMP
2478 if (NON_SAVING_SETJMP
2479 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
2480 clobbers_all
= true;
2483 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2485 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2486 record_last_reg_set_info (insn
, regno
);
2491 note_stores (PATTERN (insn
), record_last_set_info
, insn
);
2494 /* Insert implicit sets in the hash table. */
2496 && implicit_sets
[current_bb
->index
] != NULL_RTX
)
2497 hash_scan_set (implicit_sets
[current_bb
->index
],
2498 current_bb
->head
, table
);
2500 /* The next pass builds the hash table. */
2502 for (insn
= current_bb
->head
, in_libcall_block
= 0;
2503 insn
&& insn
!= NEXT_INSN (current_bb
->end
);
2504 insn
= NEXT_INSN (insn
))
2507 if (find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2508 in_libcall_block
= 1;
2509 else if (table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2510 in_libcall_block
= 0;
2511 hash_scan_insn (insn
, table
, in_libcall_block
);
2512 if (!table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2513 in_libcall_block
= 0;
2517 free (reg_avail_info
);
2518 reg_avail_info
= NULL
;
2521 /* Allocate space for the set/expr hash TABLE.
2522 N_INSNS is the number of instructions in the function.
2523 It is used to determine the number of buckets to use.
2524 SET_P determines whether set or expression table will
2528 alloc_hash_table (int n_insns
, struct hash_table
*table
, int set_p
)
2532 table
->size
= n_insns
/ 4;
2533 if (table
->size
< 11)
2536 /* Attempt to maintain efficient use of hash table.
2537 Making it an odd number is simplest for now.
2538 ??? Later take some measurements. */
2540 n
= table
->size
* sizeof (struct expr
*);
2541 table
->table
= gmalloc (n
);
2542 table
->set_p
= set_p
;
2545 /* Free things allocated by alloc_hash_table. */
2548 free_hash_table (struct hash_table
*table
)
2550 free (table
->table
);
2553 /* Compute the hash TABLE for doing copy/const propagation or
2554 expression hash table. */
2557 compute_hash_table (struct hash_table
*table
)
2559 /* Initialize count of number of entries in hash table. */
2561 memset (table
->table
, 0, table
->size
* sizeof (struct expr
*));
2563 compute_hash_table_work (table
);
2566 /* Expression tracking support. */
2568 /* Lookup pattern PAT in the expression TABLE.
2569 The result is a pointer to the table entry, or NULL if not found. */
2571 static struct expr
*
2572 lookup_expr (rtx pat
, struct hash_table
*table
)
2574 int do_not_record_p
;
2575 unsigned int hash
= hash_expr (pat
, GET_MODE (pat
), &do_not_record_p
,
2579 if (do_not_record_p
)
2582 expr
= table
->table
[hash
];
2584 while (expr
&& ! expr_equiv_p (expr
->expr
, pat
))
2585 expr
= expr
->next_same_hash
;
2590 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2591 table entry, or NULL if not found. */
2593 static struct expr
*
2594 lookup_set (unsigned int regno
, struct hash_table
*table
)
2596 unsigned int hash
= hash_set (regno
, table
->size
);
2599 expr
= table
->table
[hash
];
2601 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
)
2602 expr
= expr
->next_same_hash
;
2607 /* Return the next entry for REGNO in list EXPR. */
2609 static struct expr
*
2610 next_set (unsigned int regno
, struct expr
*expr
)
2613 expr
= expr
->next_same_hash
;
2614 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
);
2619 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2620 types may be mixed. */
2623 free_insn_expr_list_list (rtx
*listp
)
2627 for (list
= *listp
; list
; list
= next
)
2629 next
= XEXP (list
, 1);
2630 if (GET_CODE (list
) == EXPR_LIST
)
2631 free_EXPR_LIST_node (list
);
2633 free_INSN_LIST_node (list
);
2639 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2641 clear_modify_mem_tables (void)
2645 EXECUTE_IF_SET_IN_BITMAP
2646 (modify_mem_list_set
, 0, i
, free_INSN_LIST_list (modify_mem_list
+ i
));
2647 bitmap_clear (modify_mem_list_set
);
2649 EXECUTE_IF_SET_IN_BITMAP
2650 (canon_modify_mem_list_set
, 0, i
,
2651 free_insn_expr_list_list (canon_modify_mem_list
+ i
));
2652 bitmap_clear (canon_modify_mem_list_set
);
2655 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2658 free_modify_mem_tables (void)
2660 clear_modify_mem_tables ();
2661 free (modify_mem_list
);
2662 free (canon_modify_mem_list
);
2663 modify_mem_list
= 0;
2664 canon_modify_mem_list
= 0;
2667 /* Reset tables used to keep track of what's still available [since the
2668 start of the block]. */
2671 reset_opr_set_tables (void)
2673 /* Maintain a bitmap of which regs have been set since beginning of
2675 CLEAR_REG_SET (reg_set_bitmap
);
2677 /* Also keep a record of the last instruction to modify memory.
2678 For now this is very trivial, we only record whether any memory
2679 location has been modified. */
2680 clear_modify_mem_tables ();
2683 /* Return nonzero if the operands of X are not set before INSN in
2684 INSN's basic block. */
2687 oprs_not_set_p (rtx x
, rtx insn
)
2696 code
= GET_CODE (x
);
2712 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn
),
2713 INSN_CUID (insn
), x
, 0))
2716 return oprs_not_set_p (XEXP (x
, 0), insn
);
2719 return ! REGNO_REG_SET_P (reg_set_bitmap
, REGNO (x
));
2725 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2729 /* If we are about to do the last recursive call
2730 needed at this level, change it into iteration.
2731 This function is called enough to be worth it. */
2733 return oprs_not_set_p (XEXP (x
, i
), insn
);
2735 if (! oprs_not_set_p (XEXP (x
, i
), insn
))
2738 else if (fmt
[i
] == 'E')
2739 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2740 if (! oprs_not_set_p (XVECEXP (x
, i
, j
), insn
))
2747 /* Mark things set by a CALL. */
2750 mark_call (rtx insn
)
2752 if (! CONST_OR_PURE_CALL_P (insn
))
2753 record_last_mem_set_info (insn
);
2756 /* Mark things set by a SET. */
2759 mark_set (rtx pat
, rtx insn
)
2761 rtx dest
= SET_DEST (pat
);
2763 while (GET_CODE (dest
) == SUBREG
2764 || GET_CODE (dest
) == ZERO_EXTRACT
2765 || GET_CODE (dest
) == SIGN_EXTRACT
2766 || GET_CODE (dest
) == STRICT_LOW_PART
)
2767 dest
= XEXP (dest
, 0);
2769 if (GET_CODE (dest
) == REG
)
2770 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (dest
));
2771 else if (GET_CODE (dest
) == MEM
)
2772 record_last_mem_set_info (insn
);
2774 if (GET_CODE (SET_SRC (pat
)) == CALL
)
2778 /* Record things set by a CLOBBER. */
2781 mark_clobber (rtx pat
, rtx insn
)
2783 rtx clob
= XEXP (pat
, 0);
2785 while (GET_CODE (clob
) == SUBREG
|| GET_CODE (clob
) == STRICT_LOW_PART
)
2786 clob
= XEXP (clob
, 0);
2788 if (GET_CODE (clob
) == REG
)
2789 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (clob
));
2791 record_last_mem_set_info (insn
);
2794 /* Record things set by INSN.
2795 This data is used by oprs_not_set_p. */
2798 mark_oprs_set (rtx insn
)
2800 rtx pat
= PATTERN (insn
);
2803 if (GET_CODE (pat
) == SET
)
2804 mark_set (pat
, insn
);
2805 else if (GET_CODE (pat
) == PARALLEL
)
2806 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2808 rtx x
= XVECEXP (pat
, 0, i
);
2810 if (GET_CODE (x
) == SET
)
2812 else if (GET_CODE (x
) == CLOBBER
)
2813 mark_clobber (x
, insn
);
2814 else if (GET_CODE (x
) == CALL
)
2818 else if (GET_CODE (pat
) == CLOBBER
)
2819 mark_clobber (pat
, insn
);
2820 else if (GET_CODE (pat
) == CALL
)
2825 /* Classic GCSE reaching definition support. */
2827 /* Allocate reaching def variables. */
2830 alloc_rd_mem (int n_blocks
, int n_insns
)
2832 rd_kill
= sbitmap_vector_alloc (n_blocks
, n_insns
);
2833 sbitmap_vector_zero (rd_kill
, n_blocks
);
2835 rd_gen
= sbitmap_vector_alloc (n_blocks
, n_insns
);
2836 sbitmap_vector_zero (rd_gen
, n_blocks
);
2838 reaching_defs
= sbitmap_vector_alloc (n_blocks
, n_insns
);
2839 sbitmap_vector_zero (reaching_defs
, n_blocks
);
2841 rd_out
= sbitmap_vector_alloc (n_blocks
, n_insns
);
2842 sbitmap_vector_zero (rd_out
, n_blocks
);
2845 /* Free reaching def variables. */
2850 sbitmap_vector_free (rd_kill
);
2851 sbitmap_vector_free (rd_gen
);
2852 sbitmap_vector_free (reaching_defs
);
2853 sbitmap_vector_free (rd_out
);
2856 /* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
2859 handle_rd_kill_set (rtx insn
, int regno
, basic_block bb
)
2861 struct reg_set
*this_reg
;
2863 for (this_reg
= reg_set_table
[regno
]; this_reg
; this_reg
= this_reg
->next
)
2864 if (BLOCK_NUM (this_reg
->insn
) != BLOCK_NUM (insn
))
2865 SET_BIT (rd_kill
[bb
->index
], INSN_CUID (this_reg
->insn
));
2868 /* Compute the set of kill's for reaching definitions. */
2871 compute_kill_rd (void)
2879 For each set bit in `gen' of the block (i.e each insn which
2880 generates a definition in the block)
2881 Call the reg set by the insn corresponding to that bit regx
2882 Look at the linked list starting at reg_set_table[regx]
2883 For each setting of regx in the linked list, which is not in
2885 Set the bit in `kill' corresponding to that insn. */
2887 for (cuid
= 0; cuid
< max_cuid
; cuid
++)
2888 if (TEST_BIT (rd_gen
[bb
->index
], cuid
))
2890 rtx insn
= CUID_INSN (cuid
);
2891 rtx pat
= PATTERN (insn
);
2893 if (GET_CODE (insn
) == CALL_INSN
)
2895 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2896 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2897 handle_rd_kill_set (insn
, regno
, bb
);
2900 if (GET_CODE (pat
) == PARALLEL
)
2902 for (i
= XVECLEN (pat
, 0) - 1; i
>= 0; i
--)
2904 enum rtx_code code
= GET_CODE (XVECEXP (pat
, 0, i
));
2906 if ((code
== SET
|| code
== CLOBBER
)
2907 && GET_CODE (XEXP (XVECEXP (pat
, 0, i
), 0)) == REG
)
2908 handle_rd_kill_set (insn
,
2909 REGNO (XEXP (XVECEXP (pat
, 0, i
), 0)),
2913 else if (GET_CODE (pat
) == SET
&& GET_CODE (SET_DEST (pat
)) == REG
)
2914 /* Each setting of this register outside of this block
2915 must be marked in the set of kills in this block. */
2916 handle_rd_kill_set (insn
, REGNO (SET_DEST (pat
)), bb
);
2920 /* Compute the reaching definitions as in
2921 Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
2922 Chapter 10. It is the same algorithm as used for computing available
2923 expressions but applied to the gens and kills of reaching definitions. */
2928 int changed
, passes
;
2932 sbitmap_copy (rd_out
[bb
->index
] /*dst*/, rd_gen
[bb
->index
] /*src*/);
2941 sbitmap_union_of_preds (reaching_defs
[bb
->index
], rd_out
, bb
->index
);
2942 changed
|= sbitmap_union_of_diff_cg (rd_out
[bb
->index
], rd_gen
[bb
->index
],
2943 reaching_defs
[bb
->index
], rd_kill
[bb
->index
]);
2949 fprintf (gcse_file
, "reaching def computation: %d passes\n", passes
);
2952 /* Classic GCSE available expression support. */
2954 /* Allocate memory for available expression computation. */
2957 alloc_avail_expr_mem (int n_blocks
, int n_exprs
)
2959 ae_kill
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
2960 sbitmap_vector_zero (ae_kill
, n_blocks
);
2962 ae_gen
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
2963 sbitmap_vector_zero (ae_gen
, n_blocks
);
2965 ae_in
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
2966 sbitmap_vector_zero (ae_in
, n_blocks
);
2968 ae_out
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
2969 sbitmap_vector_zero (ae_out
, n_blocks
);
2973 free_avail_expr_mem (void)
2975 sbitmap_vector_free (ae_kill
);
2976 sbitmap_vector_free (ae_gen
);
2977 sbitmap_vector_free (ae_in
);
2978 sbitmap_vector_free (ae_out
);
2981 /* Compute the set of available expressions generated in each basic block. */
2984 compute_ae_gen (struct hash_table
*expr_hash_table
)
2990 /* For each recorded occurrence of each expression, set ae_gen[bb][expr].
2991 This is all we have to do because an expression is not recorded if it
2992 is not available, and the only expressions we want to work with are the
2993 ones that are recorded. */
2994 for (i
= 0; i
< expr_hash_table
->size
; i
++)
2995 for (expr
= expr_hash_table
->table
[i
]; expr
!= 0; expr
= expr
->next_same_hash
)
2996 for (occr
= expr
->avail_occr
; occr
!= 0; occr
= occr
->next
)
2997 SET_BIT (ae_gen
[BLOCK_NUM (occr
->insn
)], expr
->bitmap_index
);
3000 /* Return nonzero if expression X is killed in BB. */
3003 expr_killed_p (rtx x
, basic_block bb
)
3012 code
= GET_CODE (x
);
3016 return TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
));
3019 if (load_killed_in_block_p (bb
, get_max_uid () + 1, x
, 0))
3022 return expr_killed_p (XEXP (x
, 0), bb
);
3040 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3044 /* If we are about to do the last recursive call
3045 needed at this level, change it into iteration.
3046 This function is called enough to be worth it. */
3048 return expr_killed_p (XEXP (x
, i
), bb
);
3049 else if (expr_killed_p (XEXP (x
, i
), bb
))
3052 else if (fmt
[i
] == 'E')
3053 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3054 if (expr_killed_p (XVECEXP (x
, i
, j
), bb
))
3061 /* Compute the set of available expressions killed in each basic block. */
3064 compute_ae_kill (sbitmap
*ae_gen
, sbitmap
*ae_kill
,
3065 struct hash_table
*expr_hash_table
)
3072 for (i
= 0; i
< expr_hash_table
->size
; i
++)
3073 for (expr
= expr_hash_table
->table
[i
]; expr
; expr
= expr
->next_same_hash
)
3075 /* Skip EXPR if generated in this block. */
3076 if (TEST_BIT (ae_gen
[bb
->index
], expr
->bitmap_index
))
3079 if (expr_killed_p (expr
->expr
, bb
))
3080 SET_BIT (ae_kill
[bb
->index
], expr
->bitmap_index
);
3084 /* Actually perform the Classic GCSE optimizations. */
3086 /* Return nonzero if occurrence OCCR of expression EXPR reaches block BB.
3088 CHECK_SELF_LOOP is nonzero if we should consider a block reaching itself
3089 as a positive reach. We want to do this when there are two computations
3090 of the expression in the block.
3092 VISITED is a pointer to a working buffer for tracking which BB's have
3093 been visited. It is NULL for the top-level call.
3095 We treat reaching expressions that go through blocks containing the same
3096 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3097 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3098 2 as not reaching. The intent is to improve the probability of finding
3099 only one reaching expression and to reduce register lifetimes by picking
3100 the closest such expression. */
3103 expr_reaches_here_p_work (struct occr
*occr
, struct expr
*expr
,
3104 basic_block bb
, int check_self_loop
, char *visited
)
3108 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
3110 basic_block pred_bb
= pred
->src
;
3112 if (visited
[pred_bb
->index
])
3113 /* This predecessor has already been visited. Nothing to do. */
3115 else if (pred_bb
== bb
)
3117 /* BB loops on itself. */
3119 && TEST_BIT (ae_gen
[pred_bb
->index
], expr
->bitmap_index
)
3120 && BLOCK_NUM (occr
->insn
) == pred_bb
->index
)
3123 visited
[pred_bb
->index
] = 1;
3126 /* Ignore this predecessor if it kills the expression. */
3127 else if (TEST_BIT (ae_kill
[pred_bb
->index
], expr
->bitmap_index
))
3128 visited
[pred_bb
->index
] = 1;
3130 /* Does this predecessor generate this expression? */
3131 else if (TEST_BIT (ae_gen
[pred_bb
->index
], expr
->bitmap_index
))
3133 /* Is this the occurrence we're looking for?
3134 Note that there's only one generating occurrence per block
3135 so we just need to check the block number. */
3136 if (BLOCK_NUM (occr
->insn
) == pred_bb
->index
)
3139 visited
[pred_bb
->index
] = 1;
3142 /* Neither gen nor kill. */
3145 visited
[pred_bb
->index
] = 1;
3146 if (expr_reaches_here_p_work (occr
, expr
, pred_bb
, check_self_loop
,
3153 /* All paths have been checked. */
3157 /* This wrapper for expr_reaches_here_p_work() is to ensure that any
3158 memory allocated for that function is returned. */
3161 expr_reaches_here_p (struct occr
*occr
, struct expr
*expr
, basic_block bb
,
3162 int check_self_loop
)
3165 char *visited
= xcalloc (last_basic_block
, 1);
3167 rval
= expr_reaches_here_p_work (occr
, expr
, bb
, check_self_loop
, visited
);
3173 /* Return the instruction that computes EXPR that reaches INSN's basic block.
3174 If there is more than one such instruction, return NULL.
3176 Called only by handle_avail_expr. */
3179 computing_insn (struct expr
*expr
, rtx insn
)
3181 basic_block bb
= BLOCK_FOR_INSN (insn
);
3183 if (expr
->avail_occr
->next
== NULL
)
3185 if (BLOCK_FOR_INSN (expr
->avail_occr
->insn
) == bb
)
3186 /* The available expression is actually itself
3187 (i.e. a loop in the flow graph) so do nothing. */
3190 /* (FIXME) Case that we found a pattern that was created by
3191 a substitution that took place. */
3192 return expr
->avail_occr
->insn
;
3196 /* Pattern is computed more than once.
3197 Search backwards from this insn to see how many of these
3198 computations actually reach this insn. */
3200 rtx insn_computes_expr
= NULL
;
3203 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
3205 if (BLOCK_FOR_INSN (occr
->insn
) == bb
)
3207 /* The expression is generated in this block.
3208 The only time we care about this is when the expression
3209 is generated later in the block [and thus there's a loop].
3210 We let the normal cse pass handle the other cases. */
3211 if (INSN_CUID (insn
) < INSN_CUID (occr
->insn
)
3212 && expr_reaches_here_p (occr
, expr
, bb
, 1))
3218 insn_computes_expr
= occr
->insn
;
3221 else if (expr_reaches_here_p (occr
, expr
, bb
, 0))
3227 insn_computes_expr
= occr
->insn
;
3231 if (insn_computes_expr
== NULL
)
3234 return insn_computes_expr
;
3238 /* Return nonzero if the definition in DEF_INSN can reach INSN.
3239 Only called by can_disregard_other_sets. */
3242 def_reaches_here_p (rtx insn
, rtx def_insn
)
3246 if (TEST_BIT (reaching_defs
[BLOCK_NUM (insn
)], INSN_CUID (def_insn
)))
3249 if (BLOCK_NUM (insn
) == BLOCK_NUM (def_insn
))
3251 if (INSN_CUID (def_insn
) < INSN_CUID (insn
))
3253 if (GET_CODE (PATTERN (def_insn
)) == PARALLEL
)
3255 else if (GET_CODE (PATTERN (def_insn
)) == CLOBBER
)
3256 reg
= XEXP (PATTERN (def_insn
), 0);
3257 else if (GET_CODE (PATTERN (def_insn
)) == SET
)
3258 reg
= SET_DEST (PATTERN (def_insn
));
3262 return ! reg_set_between_p (reg
, NEXT_INSN (def_insn
), insn
);
3271 /* Return nonzero if *ADDR_THIS_REG can only have one value at INSN. The
3272 value returned is the number of definitions that reach INSN. Returning a
3273 value of zero means that [maybe] more than one definition reaches INSN and
3274 the caller can't perform whatever optimization it is trying. i.e. it is
3275 always safe to return zero. */
3278 can_disregard_other_sets (struct reg_set
**addr_this_reg
, rtx insn
, int for_combine
)
3280 int number_of_reaching_defs
= 0;
3281 struct reg_set
*this_reg
;
3283 for (this_reg
= *addr_this_reg
; this_reg
!= 0; this_reg
= this_reg
->next
)
3284 if (def_reaches_here_p (insn
, this_reg
->insn
))
3286 number_of_reaching_defs
++;
3287 /* Ignore parallels for now. */
3288 if (GET_CODE (PATTERN (this_reg
->insn
)) == PARALLEL
)
3292 && (GET_CODE (PATTERN (this_reg
->insn
)) == CLOBBER
3293 || ! rtx_equal_p (SET_SRC (PATTERN (this_reg
->insn
)),
3294 SET_SRC (PATTERN (insn
)))))
3295 /* A setting of the reg to a different value reaches INSN. */
3298 if (number_of_reaching_defs
> 1)
3300 /* If in this setting the value the register is being set to is
3301 equal to the previous value the register was set to and this
3302 setting reaches the insn we are trying to do the substitution
3303 on then we are ok. */
3304 if (GET_CODE (PATTERN (this_reg
->insn
)) == CLOBBER
)
3306 else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg
->insn
)),
3307 SET_SRC (PATTERN (insn
))))
3311 *addr_this_reg
= this_reg
;
3314 return number_of_reaching_defs
;
3317 /* Expression computed by insn is available and the substitution is legal,
3318 so try to perform the substitution.
3320 The result is nonzero if any changes were made. */
3323 handle_avail_expr (rtx insn
, struct expr
*expr
)
3325 rtx pat
, insn_computes_expr
, expr_set
;
3327 struct reg_set
*this_reg
;
3328 int found_setting
, use_src
;
3331 /* We only handle the case where one computation of the expression
3332 reaches this instruction. */
3333 insn_computes_expr
= computing_insn (expr
, insn
);
3334 if (insn_computes_expr
== NULL
)
3336 expr_set
= single_set (insn_computes_expr
);
3343 /* At this point we know only one computation of EXPR outside of this
3344 block reaches this insn. Now try to find a register that the
3345 expression is computed into. */
3346 if (GET_CODE (SET_SRC (expr_set
)) == REG
)
3348 /* This is the case when the available expression that reaches
3349 here has already been handled as an available expression. */
3350 unsigned int regnum_for_replacing
3351 = REGNO (SET_SRC (expr_set
));
3353 /* If the register was created by GCSE we can't use `reg_set_table',
3354 however we know it's set only once. */
3355 if (regnum_for_replacing
>= max_gcse_regno
3356 /* If the register the expression is computed into is set only once,
3357 or only one set reaches this insn, we can use it. */
3358 || (((this_reg
= reg_set_table
[regnum_for_replacing
]),
3359 this_reg
->next
== NULL
)
3360 || can_disregard_other_sets (&this_reg
, insn
, 0)))
3369 unsigned int regnum_for_replacing
3370 = REGNO (SET_DEST (expr_set
));
3372 /* This shouldn't happen. */
3373 if (regnum_for_replacing
>= max_gcse_regno
)
3376 this_reg
= reg_set_table
[regnum_for_replacing
];
3378 /* If the register the expression is computed into is set only once,
3379 or only one set reaches this insn, use it. */
3380 if (this_reg
->next
== NULL
3381 || can_disregard_other_sets (&this_reg
, insn
, 0))
3387 pat
= PATTERN (insn
);
3389 to
= SET_SRC (expr_set
);
3391 to
= SET_DEST (expr_set
);
3392 changed
= validate_change (insn
, &SET_SRC (pat
), to
, 0);
3394 /* We should be able to ignore the return code from validate_change but
3395 to play it safe we check. */
3399 if (gcse_file
!= NULL
)
3401 fprintf (gcse_file
, "GCSE: Replacing the source in insn %d with",
3403 fprintf (gcse_file
, " reg %d %s insn %d\n",
3404 REGNO (to
), use_src
? "from" : "set in",
3405 INSN_UID (insn_computes_expr
));
3410 /* The register that the expr is computed into is set more than once. */
3411 else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
3413 /* Insert an insn after insnx that copies the reg set in insnx
3414 into a new pseudo register call this new register REGN.
3415 From insnb until end of basic block or until REGB is set
3416 replace all uses of REGB with REGN. */
3419 to
= gen_reg_rtx (GET_MODE (SET_DEST (expr_set
)));
3421 /* Generate the new insn. */
3422 /* ??? If the change fails, we return 0, even though we created
3423 an insn. I think this is ok. */
3425 = emit_insn_after (gen_rtx_SET (VOIDmode
, to
,
3426 SET_DEST (expr_set
)),
3427 insn_computes_expr
);
3429 /* Keep register set table up to date. */
3430 record_one_set (REGNO (to
), new_insn
);
3432 gcse_create_count
++;
3433 if (gcse_file
!= NULL
)
3435 fprintf (gcse_file
, "GCSE: Creating insn %d to copy value of reg %d",
3436 INSN_UID (NEXT_INSN (insn_computes_expr
)),
3437 REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr
)))));
3438 fprintf (gcse_file
, ", computed in insn %d,\n",
3439 INSN_UID (insn_computes_expr
));
3440 fprintf (gcse_file
, " into newly allocated reg %d\n",
3444 pat
= PATTERN (insn
);
3446 /* Do register replacement for INSN. */
3447 changed
= validate_change (insn
, &SET_SRC (pat
),
3449 (NEXT_INSN (insn_computes_expr
))),
3452 /* We should be able to ignore the return code from validate_change but
3453 to play it safe we check. */
3457 if (gcse_file
!= NULL
)
3460 "GCSE: Replacing the source in insn %d with reg %d ",
3462 REGNO (SET_DEST (PATTERN (NEXT_INSN
3463 (insn_computes_expr
)))));
3464 fprintf (gcse_file
, "set in insn %d\n",
3465 INSN_UID (insn_computes_expr
));
3473 /* Perform classic GCSE. This is called by one_classic_gcse_pass after all
3474 the dataflow analysis has been done.
3476 The result is nonzero if a change was made. */
3485 /* Note we start at block 1. */
3487 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3491 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
3493 /* Reset tables used to keep track of what's still valid [since the
3494 start of the block]. */
3495 reset_opr_set_tables ();
3497 for (insn
= bb
->head
;
3498 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
3499 insn
= NEXT_INSN (insn
))
3501 /* Is insn of form (set (pseudo-reg) ...)? */
3502 if (GET_CODE (insn
) == INSN
3503 && GET_CODE (PATTERN (insn
)) == SET
3504 && GET_CODE (SET_DEST (PATTERN (insn
))) == REG
3505 && REGNO (SET_DEST (PATTERN (insn
))) >= FIRST_PSEUDO_REGISTER
)
3507 rtx pat
= PATTERN (insn
);
3508 rtx src
= SET_SRC (pat
);
3511 if (want_to_gcse_p (src
)
3512 /* Is the expression recorded? */
3513 && ((expr
= lookup_expr (src
, &expr_hash_table
)) != NULL
)
3514 /* Is the expression available [at the start of the
3516 && TEST_BIT (ae_in
[bb
->index
], expr
->bitmap_index
)
3517 /* Are the operands unchanged since the start of the
3519 && oprs_not_set_p (src
, insn
))
3520 changed
|= handle_avail_expr (insn
, expr
);
3523 /* Keep track of everything modified by this insn. */
3524 /* ??? Need to be careful w.r.t. mods done to INSN. */
3526 mark_oprs_set (insn
);
3533 /* Top level routine to perform one classic GCSE pass.
3535 Return nonzero if a change was made. */
3538 one_classic_gcse_pass (int pass
)
3542 gcse_subst_count
= 0;
3543 gcse_create_count
= 0;
3545 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
3546 alloc_rd_mem (last_basic_block
, max_cuid
);
3547 compute_hash_table (&expr_hash_table
);
3549 dump_hash_table (gcse_file
, "Expression", &expr_hash_table
);
3551 if (expr_hash_table
.n_elems
> 0)
3555 alloc_avail_expr_mem (last_basic_block
, expr_hash_table
.n_elems
);
3556 compute_ae_gen (&expr_hash_table
);
3557 compute_ae_kill (ae_gen
, ae_kill
, &expr_hash_table
);
3558 compute_available (ae_gen
, ae_kill
, ae_out
, ae_in
);
3559 changed
= classic_gcse ();
3560 free_avail_expr_mem ();
3564 free_hash_table (&expr_hash_table
);
3568 fprintf (gcse_file
, "\n");
3569 fprintf (gcse_file
, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
3570 current_function_name
, pass
, bytes_used
, gcse_subst_count
);
3571 fprintf (gcse_file
, "%d insns created\n", gcse_create_count
);
3577 /* Compute copy/constant propagation working variables. */
3579 /* Local properties of assignments. */
3580 static sbitmap
*cprop_pavloc
;
3581 static sbitmap
*cprop_absaltered
;
3583 /* Global properties of assignments (computed from the local properties). */
3584 static sbitmap
*cprop_avin
;
3585 static sbitmap
*cprop_avout
;
3587 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
3588 basic blocks. N_SETS is the number of sets. */
3591 alloc_cprop_mem (int n_blocks
, int n_sets
)
3593 cprop_pavloc
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3594 cprop_absaltered
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3596 cprop_avin
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3597 cprop_avout
= sbitmap_vector_alloc (n_blocks
, n_sets
);
3600 /* Free vars used by copy/const propagation. */
3603 free_cprop_mem (void)
3605 sbitmap_vector_free (cprop_pavloc
);
3606 sbitmap_vector_free (cprop_absaltered
);
3607 sbitmap_vector_free (cprop_avin
);
3608 sbitmap_vector_free (cprop_avout
);
3611 /* For each block, compute whether X is transparent. X is either an
3612 expression or an assignment [though we don't care which, for this context
3613 an assignment is treated as an expression]. For each block where an
3614 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
3618 compute_transp (rtx x
, int indx
, sbitmap
*bmap
, int set_p
)
3626 /* repeat is used to turn tail-recursion into iteration since GCC
3627 can't do it when there's no return value. */
3633 code
= GET_CODE (x
);
3639 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
3642 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
3643 SET_BIT (bmap
[bb
->index
], indx
);
3647 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
3648 SET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
3653 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
3656 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
3657 RESET_BIT (bmap
[bb
->index
], indx
);
3661 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
3662 RESET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
3671 rtx list_entry
= canon_modify_mem_list
[bb
->index
];
3675 rtx dest
, dest_addr
;
3677 if (GET_CODE (XEXP (list_entry
, 0)) == CALL_INSN
)
3680 SET_BIT (bmap
[bb
->index
], indx
);
3682 RESET_BIT (bmap
[bb
->index
], indx
);
3685 /* LIST_ENTRY must be an INSN of some kind that sets memory.
3686 Examine each hunk of memory that is modified. */
3688 dest
= XEXP (list_entry
, 0);
3689 list_entry
= XEXP (list_entry
, 1);
3690 dest_addr
= XEXP (list_entry
, 0);
3692 if (canon_true_dependence (dest
, GET_MODE (dest
), dest_addr
,
3693 x
, rtx_addr_varies_p
))
3696 SET_BIT (bmap
[bb
->index
], indx
);
3698 RESET_BIT (bmap
[bb
->index
], indx
);
3701 list_entry
= XEXP (list_entry
, 1);
3724 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3728 /* If we are about to do the last recursive call
3729 needed at this level, change it into iteration.
3730 This function is called enough to be worth it. */
3737 compute_transp (XEXP (x
, i
), indx
, bmap
, set_p
);
3739 else if (fmt
[i
] == 'E')
3740 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3741 compute_transp (XVECEXP (x
, i
, j
), indx
, bmap
, set_p
);
3745 /* Top level routine to do the dataflow analysis needed by copy/const
3749 compute_cprop_data (void)
3751 compute_local_properties (cprop_absaltered
, cprop_pavloc
, NULL
, &set_hash_table
);
3752 compute_available (cprop_pavloc
, cprop_absaltered
,
3753 cprop_avout
, cprop_avin
);
3756 /* Copy/constant propagation. */
3758 /* Maximum number of register uses in an insn that we handle. */
3761 /* Table of uses found in an insn.
3762 Allocated statically to avoid alloc/free complexity and overhead. */
3763 static struct reg_use reg_use_table
[MAX_USES
];
3765 /* Index into `reg_use_table' while building it. */
3766 static int reg_use_count
;
3768 /* Set up a list of register numbers used in INSN. The found uses are stored
3769 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
3770 and contains the number of uses in the table upon exit.
3772 ??? If a register appears multiple times we will record it multiple times.
3773 This doesn't hurt anything but it will slow things down. */
3776 find_used_regs (rtx
*xptr
, void *data ATTRIBUTE_UNUSED
)
3783 /* repeat is used to turn tail-recursion into iteration since GCC
3784 can't do it when there's no return value. */
3789 code
= GET_CODE (x
);
3792 if (reg_use_count
== MAX_USES
)
3795 reg_use_table
[reg_use_count
].reg_rtx
= x
;
3799 /* Recursively scan the operands of this expression. */
3801 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3805 /* If we are about to do the last recursive call
3806 needed at this level, change it into iteration.
3807 This function is called enough to be worth it. */
3814 find_used_regs (&XEXP (x
, i
), data
);
3816 else if (fmt
[i
] == 'E')
3817 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3818 find_used_regs (&XVECEXP (x
, i
, j
), data
);
3822 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
3823 Returns nonzero is successful. */
3826 try_replace_reg (rtx from
, rtx to
, rtx insn
)
3828 rtx note
= find_reg_equal_equiv_note (insn
);
3831 rtx set
= single_set (insn
);
3833 validate_replace_src_group (from
, to
, insn
);
3834 if (num_changes_pending () && apply_change_group ())
3837 /* Try to simplify SET_SRC if we have substituted a constant. */
3838 if (success
&& set
&& CONSTANT_P (to
))
3840 src
= simplify_rtx (SET_SRC (set
));
3843 validate_change (insn
, &SET_SRC (set
), src
, 0);
3846 /* If there is already a NOTE, update the expression in it with our
3849 XEXP (note
, 0) = simplify_replace_rtx (XEXP (note
, 0), from
, to
);
3851 if (!success
&& set
&& reg_mentioned_p (from
, SET_SRC (set
)))
3853 /* If above failed and this is a single set, try to simplify the source of
3854 the set given our substitution. We could perhaps try this for multiple
3855 SETs, but it probably won't buy us anything. */
3856 src
= simplify_replace_rtx (SET_SRC (set
), from
, to
);
3858 if (!rtx_equal_p (src
, SET_SRC (set
))
3859 && validate_change (insn
, &SET_SRC (set
), src
, 0))
3862 /* If we've failed to do replacement, have a single SET, don't already
3863 have a note, and have no special SET, add a REG_EQUAL note to not
3864 lose information. */
3865 if (!success
&& note
== 0 && set
!= 0
3866 && GET_CODE (XEXP (set
, 0)) != ZERO_EXTRACT
3867 && GET_CODE (XEXP (set
, 0)) != SIGN_EXTRACT
)
3868 note
= set_unique_reg_note (insn
, REG_EQUAL
, copy_rtx (src
));
3871 /* REG_EQUAL may get simplified into register.
3872 We don't allow that. Remove that note. This code ought
3873 not to happen, because previous code ought to synthesize
3874 reg-reg move, but be on the safe side. */
3875 if (note
&& REG_P (XEXP (note
, 0)))
3876 remove_note (insn
, note
);
3881 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
3882 NULL no such set is found. */
3884 static struct expr
*
3885 find_avail_set (int regno
, rtx insn
)
3887 /* SET1 contains the last set found that can be returned to the caller for
3888 use in a substitution. */
3889 struct expr
*set1
= 0;
3891 /* Loops are not possible here. To get a loop we would need two sets
3892 available at the start of the block containing INSN. ie we would
3893 need two sets like this available at the start of the block:
3895 (set (reg X) (reg Y))
3896 (set (reg Y) (reg X))
3898 This can not happen since the set of (reg Y) would have killed the
3899 set of (reg X) making it unavailable at the start of this block. */
3903 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
3905 /* Find a set that is available at the start of the block
3906 which contains INSN. */
3909 if (TEST_BIT (cprop_avin
[BLOCK_NUM (insn
)], set
->bitmap_index
))
3911 set
= next_set (regno
, set
);
3914 /* If no available set was found we've reached the end of the
3915 (possibly empty) copy chain. */
3919 if (GET_CODE (set
->expr
) != SET
)
3922 src
= SET_SRC (set
->expr
);
3924 /* We know the set is available.
3925 Now check that SRC is ANTLOC (i.e. none of the source operands
3926 have changed since the start of the block).
3928 If the source operand changed, we may still use it for the next
3929 iteration of this loop, but we may not use it for substitutions. */
3931 if (gcse_constant_p (src
) || oprs_not_set_p (src
, insn
))
3934 /* If the source of the set is anything except a register, then
3935 we have reached the end of the copy chain. */
3936 if (GET_CODE (src
) != REG
)
3939 /* Follow the copy chain, ie start another iteration of the loop
3940 and see if we have an available copy into SRC. */
3941 regno
= REGNO (src
);
3944 /* SET1 holds the last set that was available and anticipatable at
3949 /* Subroutine of cprop_insn that tries to propagate constants into
3950 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
3951 it is the instruction that immediately precedes JUMP, and must be a
3952 single SET of a register. FROM is what we will try to replace,
3953 SRC is the constant we will try to substitute for it. Returns nonzero
3954 if a change was made. */
3957 cprop_jump (basic_block bb
, rtx setcc
, rtx jump
, rtx from
, rtx src
)
3959 rtx
new, set_src
, note_src
;
3960 rtx set
= pc_set (jump
);
3961 rtx note
= find_reg_equal_equiv_note (jump
);
3965 note_src
= XEXP (note
, 0);
3966 if (GET_CODE (note_src
) == EXPR_LIST
)
3967 note_src
= NULL_RTX
;
3969 else note_src
= NULL_RTX
;
3971 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
3972 set_src
= note_src
? note_src
: SET_SRC (set
);
3974 /* First substitute the SETCC condition into the JUMP instruction,
3975 then substitute that given values into this expanded JUMP. */
3976 if (setcc
!= NULL_RTX
3977 && !modified_between_p (from
, setcc
, jump
)
3978 && !modified_between_p (src
, setcc
, jump
))
3981 rtx setcc_set
= single_set (setcc
);
3982 rtx setcc_note
= find_reg_equal_equiv_note (setcc
);
3983 setcc_src
= (setcc_note
&& GET_CODE (XEXP (setcc_note
, 0)) != EXPR_LIST
)
3984 ? XEXP (setcc_note
, 0) : SET_SRC (setcc_set
);
3985 set_src
= simplify_replace_rtx (set_src
, SET_DEST (setcc_set
),
3991 new = simplify_replace_rtx (set_src
, from
, src
);
3993 /* If no simplification can be made, then try the next register. */
3994 if (rtx_equal_p (new, SET_SRC (set
)))
3997 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
4002 /* Ensure the value computed inside the jump insn to be equivalent
4003 to one computed by setcc. */
4004 if (setcc
&& modified_in_p (new, setcc
))
4006 if (! validate_change (jump
, &SET_SRC (set
), new, 0))
4008 /* When (some) constants are not valid in a comparison, and there
4009 are two registers to be replaced by constants before the entire
4010 comparison can be folded into a constant, we need to keep
4011 intermediate information in REG_EQUAL notes. For targets with
4012 separate compare insns, such notes are added by try_replace_reg.
4013 When we have a combined compare-and-branch instruction, however,
4014 we need to attach a note to the branch itself to make this
4015 optimization work. */
4017 if (!rtx_equal_p (new, note_src
))
4018 set_unique_reg_note (jump
, REG_EQUAL
, copy_rtx (new));
4022 /* Remove REG_EQUAL note after simplification. */
4024 remove_note (jump
, note
);
4026 /* If this has turned into an unconditional jump,
4027 then put a barrier after it so that the unreachable
4028 code will be deleted. */
4029 if (GET_CODE (SET_SRC (set
)) == LABEL_REF
)
4030 emit_barrier_after (jump
);
4034 /* Delete the cc0 setter. */
4035 if (setcc
!= NULL
&& CC0_P (SET_DEST (single_set (setcc
))))
4036 delete_insn (setcc
);
4039 run_jump_opt_after_gcse
= 1;
4042 if (gcse_file
!= NULL
)
4045 "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
4046 REGNO (from
), INSN_UID (jump
));
4047 print_rtl (gcse_file
, src
);
4048 fprintf (gcse_file
, "\n");
4050 purge_dead_edges (bb
);
4056 constprop_register (rtx insn
, rtx from
, rtx to
, int alter_jumps
)
4060 /* Check for reg or cc0 setting instructions followed by
4061 conditional branch instructions first. */
4063 && (sset
= single_set (insn
)) != NULL
4065 && any_condjump_p (NEXT_INSN (insn
)) && onlyjump_p (NEXT_INSN (insn
)))
4067 rtx dest
= SET_DEST (sset
);
4068 if ((REG_P (dest
) || CC0_P (dest
))
4069 && cprop_jump (BLOCK_FOR_INSN (insn
), insn
, NEXT_INSN (insn
), from
, to
))
4073 /* Handle normal insns next. */
4074 if (GET_CODE (insn
) == INSN
4075 && try_replace_reg (from
, to
, insn
))
4078 /* Try to propagate a CONST_INT into a conditional jump.
4079 We're pretty specific about what we will handle in this
4080 code, we can extend this as necessary over time.
4082 Right now the insn in question must look like
4083 (set (pc) (if_then_else ...)) */
4084 else if (alter_jumps
&& any_condjump_p (insn
) && onlyjump_p (insn
))
4085 return cprop_jump (BLOCK_FOR_INSN (insn
), NULL
, insn
, from
, to
);
4089 /* Perform constant and copy propagation on INSN.
4090 The result is nonzero if a change was made. */
4093 cprop_insn (rtx insn
, int alter_jumps
)
4095 struct reg_use
*reg_used
;
4103 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4105 note
= find_reg_equal_equiv_note (insn
);
4107 /* We may win even when propagating constants into notes. */
4109 find_used_regs (&XEXP (note
, 0), NULL
);
4111 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
4112 reg_used
++, reg_use_count
--)
4114 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
4118 /* Ignore registers created by GCSE.
4119 We do this because ... */
4120 if (regno
>= max_gcse_regno
)
4123 /* If the register has already been set in this block, there's
4124 nothing we can do. */
4125 if (! oprs_not_set_p (reg_used
->reg_rtx
, insn
))
4128 /* Find an assignment that sets reg_used and is available
4129 at the start of the block. */
4130 set
= find_avail_set (regno
, insn
);
4135 /* ??? We might be able to handle PARALLELs. Later. */
4136 if (GET_CODE (pat
) != SET
)
4139 src
= SET_SRC (pat
);
4141 /* Constant propagation. */
4142 if (gcse_constant_p (src
))
4144 if (constprop_register (insn
, reg_used
->reg_rtx
, src
, alter_jumps
))
4148 if (gcse_file
!= NULL
)
4150 fprintf (gcse_file
, "GLOBAL CONST-PROP: Replacing reg %d in ", regno
);
4151 fprintf (gcse_file
, "insn %d with constant ", INSN_UID (insn
));
4152 print_rtl (gcse_file
, src
);
4153 fprintf (gcse_file
, "\n");
4155 if (INSN_DELETED_P (insn
))
4159 else if (GET_CODE (src
) == REG
4160 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
4161 && REGNO (src
) != regno
)
4163 if (try_replace_reg (reg_used
->reg_rtx
, src
, insn
))
4167 if (gcse_file
!= NULL
)
4169 fprintf (gcse_file
, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
4170 regno
, INSN_UID (insn
));
4171 fprintf (gcse_file
, " with reg %d\n", REGNO (src
));
4174 /* The original insn setting reg_used may or may not now be
4175 deletable. We leave the deletion to flow. */
4176 /* FIXME: If it turns out that the insn isn't deletable,
4177 then we may have unnecessarily extended register lifetimes
4178 and made things worse. */
4186 /* Like find_used_regs, but avoid recording uses that appear in
4187 input-output contexts such as zero_extract or pre_dec. This
4188 restricts the cases we consider to those for which local cprop
4189 can legitimately make replacements. */
4192 local_cprop_find_used_regs (rtx
*xptr
, void *data
)
4199 switch (GET_CODE (x
))
4203 case STRICT_LOW_PART
:
4212 /* Can only legitimately appear this early in the context of
4213 stack pushes for function arguments, but handle all of the
4214 codes nonetheless. */
4218 /* Setting a subreg of a register larger than word_mode leaves
4219 the non-written words unchanged. */
4220 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x
))) > BITS_PER_WORD
)
4228 find_used_regs (xptr
, data
);
4231 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4232 their REG_EQUAL notes need updating. */
4235 do_local_cprop (rtx x
, rtx insn
, int alter_jumps
, rtx
*libcall_sp
)
4237 rtx newreg
= NULL
, newcnst
= NULL
;
4239 /* Rule out USE instructions and ASM statements as we don't want to
4240 change the hard registers mentioned. */
4241 if (GET_CODE (x
) == REG
4242 && (REGNO (x
) >= FIRST_PSEUDO_REGISTER
4243 || (GET_CODE (PATTERN (insn
)) != USE
4244 && asm_noperands (PATTERN (insn
)) < 0)))
4246 cselib_val
*val
= cselib_lookup (x
, GET_MODE (x
), 0);
4247 struct elt_loc_list
*l
;
4251 for (l
= val
->locs
; l
; l
= l
->next
)
4253 rtx this_rtx
= l
->loc
;
4259 if (gcse_constant_p (this_rtx
))
4261 if (REG_P (this_rtx
) && REGNO (this_rtx
) >= FIRST_PSEUDO_REGISTER
4262 /* Don't copy propagate if it has attached REG_EQUIV note.
4263 At this point this only function parameters should have
4264 REG_EQUIV notes and if the argument slot is used somewhere
4265 explicitly, it means address of parameter has been taken,
4266 so we should not extend the lifetime of the pseudo. */
4267 && (!(note
= find_reg_note (l
->setting_insn
, REG_EQUIV
, NULL_RTX
))
4268 || GET_CODE (XEXP (note
, 0)) != MEM
))
4271 if (newcnst
&& constprop_register (insn
, x
, newcnst
, alter_jumps
))
4273 /* If we find a case where we can't fix the retval REG_EQUAL notes
4274 match the new register, we either have to abandon this replacement
4275 or fix delete_trivially_dead_insns to preserve the setting insn,
4276 or make it delete the REG_EUAQL note, and fix up all passes that
4277 require the REG_EQUAL note there. */
4278 if (!adjust_libcall_notes (x
, newcnst
, insn
, libcall_sp
))
4280 if (gcse_file
!= NULL
)
4282 fprintf (gcse_file
, "LOCAL CONST-PROP: Replacing reg %d in ",
4284 fprintf (gcse_file
, "insn %d with constant ",
4286 print_rtl (gcse_file
, newcnst
);
4287 fprintf (gcse_file
, "\n");
4292 else if (newreg
&& newreg
!= x
&& try_replace_reg (x
, newreg
, insn
))
4294 adjust_libcall_notes (x
, newreg
, insn
, libcall_sp
);
4295 if (gcse_file
!= NULL
)
4298 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
4299 REGNO (x
), INSN_UID (insn
));
4300 fprintf (gcse_file
, " with reg %d\n", REGNO (newreg
));
4309 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4310 their REG_EQUAL notes need updating to reflect that OLDREG has been
4311 replaced with NEWVAL in INSN. Return true if all substitutions could
4314 adjust_libcall_notes (rtx oldreg
, rtx newval
, rtx insn
, rtx
*libcall_sp
)
4318 while ((end
= *libcall_sp
++))
4320 rtx note
= find_reg_equal_equiv_note (end
);
4327 if (reg_set_between_p (newval
, PREV_INSN (insn
), end
))
4331 note
= find_reg_equal_equiv_note (end
);
4334 if (reg_mentioned_p (newval
, XEXP (note
, 0)))
4337 while ((end
= *libcall_sp
++));
4341 XEXP (note
, 0) = replace_rtx (XEXP (note
, 0), oldreg
, newval
);
4347 #define MAX_NESTED_LIBCALLS 9
4350 local_cprop_pass (int alter_jumps
)
4353 struct reg_use
*reg_used
;
4354 rtx libcall_stack
[MAX_NESTED_LIBCALLS
+ 1], *libcall_sp
;
4355 bool changed
= false;
4358 libcall_sp
= &libcall_stack
[MAX_NESTED_LIBCALLS
];
4360 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
4364 rtx note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
4368 if (libcall_sp
== libcall_stack
)
4370 *--libcall_sp
= XEXP (note
, 0);
4372 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
4375 note
= find_reg_equal_equiv_note (insn
);
4379 note_uses (&PATTERN (insn
), local_cprop_find_used_regs
, NULL
);
4381 local_cprop_find_used_regs (&XEXP (note
, 0), NULL
);
4383 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
4384 reg_used
++, reg_use_count
--)
4385 if (do_local_cprop (reg_used
->reg_rtx
, insn
, alter_jumps
,
4391 if (INSN_DELETED_P (insn
))
4394 while (reg_use_count
);
4396 cselib_process_insn (insn
);
4399 /* Global analysis may get into infinite loops for unreachable blocks. */
4400 if (changed
&& alter_jumps
)
4402 delete_unreachable_blocks ();
4403 free_reg_set_mem ();
4404 alloc_reg_set_mem (max_reg_num ());
4405 compute_sets (get_insns ());
4409 /* Forward propagate copies. This includes copies and constants. Return
4410 nonzero if a change was made. */
4413 cprop (int alter_jumps
)
4419 /* Note we start at block 1. */
4420 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
4422 if (gcse_file
!= NULL
)
4423 fprintf (gcse_file
, "\n");
4428 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
4430 /* Reset tables used to keep track of what's still valid [since the
4431 start of the block]. */
4432 reset_opr_set_tables ();
4434 for (insn
= bb
->head
;
4435 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
4436 insn
= NEXT_INSN (insn
))
4439 changed
|= cprop_insn (insn
, alter_jumps
);
4441 /* Keep track of everything modified by this insn. */
4442 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
4443 call mark_oprs_set if we turned the insn into a NOTE. */
4444 if (GET_CODE (insn
) != NOTE
)
4445 mark_oprs_set (insn
);
4449 if (gcse_file
!= NULL
)
4450 fprintf (gcse_file
, "\n");
4455 /* Similar to get_condition, only the resulting condition must be
4456 valid at JUMP, instead of at EARLIEST.
4458 This differs from noce_get_condition in ifcvt.c in that we prefer not to
4459 settle for the condition variable in the jump instruction being integral.
4460 We prefer to be able to record the value of a user variable, rather than
4461 the value of a temporary used in a condition. This could be solved by
4462 recording the value of *every* register scaned by canonicalize_condition,
4463 but this would require some code reorganization. */
4466 fis_get_condition (rtx jump
)
4468 rtx cond
, set
, tmp
, insn
, earliest
;
4471 if (! any_condjump_p (jump
))
4474 set
= pc_set (jump
);
4475 cond
= XEXP (SET_SRC (set
), 0);
4477 /* If this branches to JUMP_LABEL when the condition is false,
4478 reverse the condition. */
4479 reverse
= (GET_CODE (XEXP (SET_SRC (set
), 2)) == LABEL_REF
4480 && XEXP (XEXP (SET_SRC (set
), 2), 0) == JUMP_LABEL (jump
));
4482 /* Use canonicalize_condition to do the dirty work of manipulating
4483 MODE_CC values and COMPARE rtx codes. */
4484 tmp
= canonicalize_condition (jump
, cond
, reverse
, &earliest
, NULL_RTX
,
4489 /* Verify that the given condition is valid at JUMP by virtue of not
4490 having been modified since EARLIEST. */
4491 for (insn
= earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
4492 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
4497 /* The condition was modified. See if we can get a partial result
4498 that doesn't follow all the reversals. Perhaps combine can fold
4499 them together later. */
4500 tmp
= XEXP (tmp
, 0);
4501 if (!REG_P (tmp
) || GET_MODE_CLASS (GET_MODE (tmp
)) != MODE_INT
)
4503 tmp
= canonicalize_condition (jump
, cond
, reverse
, &earliest
, tmp
,
4508 /* For sanity's sake, re-validate the new result. */
4509 for (insn
= earliest
; insn
!= jump
; insn
= NEXT_INSN (insn
))
4510 if (INSN_P (insn
) && modified_in_p (tmp
, insn
))
4516 /* Find the implicit sets of a function. An "implicit set" is a constraint
4517 on the value of a variable, implied by a conditional jump. For example,
4518 following "if (x == 2)", the then branch may be optimized as though the
4519 conditional performed an "explicit set", in this example, "x = 2". This
4520 function records the set patterns that are implicit at the start of each
4524 find_implicit_sets (void)
4526 basic_block bb
, dest
;
4532 /* Check for more than one successor. */
4533 if (bb
->succ
&& bb
->succ
->succ_next
)
4535 cond
= fis_get_condition (bb
->end
);
4538 && (GET_CODE (cond
) == EQ
|| GET_CODE (cond
) == NE
)
4539 && GET_CODE (XEXP (cond
, 0)) == REG
4540 && REGNO (XEXP (cond
, 0)) >= FIRST_PSEUDO_REGISTER
4541 && gcse_constant_p (XEXP (cond
, 1)))
4543 dest
= GET_CODE (cond
) == EQ
? BRANCH_EDGE (bb
)->dest
4544 : FALLTHRU_EDGE (bb
)->dest
;
4546 if (dest
&& ! dest
->pred
->pred_next
4547 && dest
!= EXIT_BLOCK_PTR
)
4549 new = gen_rtx_SET (VOIDmode
, XEXP (cond
, 0),
4551 implicit_sets
[dest
->index
] = new;
4554 fprintf(gcse_file
, "Implicit set of reg %d in ",
4555 REGNO (XEXP (cond
, 0)));
4556 fprintf(gcse_file
, "basic block %d\n", dest
->index
);
4564 fprintf (gcse_file
, "Found %d implicit sets\n", count
);
4567 /* Perform one copy/constant propagation pass.
4568 PASS is the pass count. If CPROP_JUMPS is true, perform constant
4569 propagation into conditional jumps. If BYPASS_JUMPS is true,
4570 perform conditional jump bypassing optimizations. */
4573 one_cprop_pass (int pass
, int cprop_jumps
, int bypass_jumps
)
4577 const_prop_count
= 0;
4578 copy_prop_count
= 0;
4580 local_cprop_pass (cprop_jumps
);
4582 /* Determine implicit sets. */
4583 implicit_sets
= xcalloc (last_basic_block
, sizeof (rtx
));
4584 find_implicit_sets ();
4586 alloc_hash_table (max_cuid
, &set_hash_table
, 1);
4587 compute_hash_table (&set_hash_table
);
4589 /* Free implicit_sets before peak usage. */
4590 free (implicit_sets
);
4591 implicit_sets
= NULL
;
4594 dump_hash_table (gcse_file
, "SET", &set_hash_table
);
4595 if (set_hash_table
.n_elems
> 0)
4597 alloc_cprop_mem (last_basic_block
, set_hash_table
.n_elems
);
4598 compute_cprop_data ();
4599 changed
= cprop (cprop_jumps
);
4601 changed
|= bypass_conditional_jumps ();
4605 free_hash_table (&set_hash_table
);
4609 fprintf (gcse_file
, "CPROP of %s, pass %d: %d bytes needed, ",
4610 current_function_name
, pass
, bytes_used
);
4611 fprintf (gcse_file
, "%d const props, %d copy props\n\n",
4612 const_prop_count
, copy_prop_count
);
4614 /* Global analysis may get into infinite loops for unreachable blocks. */
4615 if (changed
&& cprop_jumps
)
4616 delete_unreachable_blocks ();
4621 /* Bypass conditional jumps. */
4623 /* The value of last_basic_block at the beginning of the jump_bypass
4624 pass. The use of redirect_edge_and_branch_force may introduce new
4625 basic blocks, but the data flow analysis is only valid for basic
4626 block indices less than bypass_last_basic_block. */
4628 static int bypass_last_basic_block
;
4630 /* Find a set of REGNO to a constant that is available at the end of basic
4631 block BB. Returns NULL if no such set is found. Based heavily upon
4634 static struct expr
*
4635 find_bypass_set (int regno
, int bb
)
4637 struct expr
*result
= 0;
4642 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
4646 if (TEST_BIT (cprop_avout
[bb
], set
->bitmap_index
))
4648 set
= next_set (regno
, set
);
4654 if (GET_CODE (set
->expr
) != SET
)
4657 src
= SET_SRC (set
->expr
);
4658 if (gcse_constant_p (src
))
4661 if (GET_CODE (src
) != REG
)
4664 regno
= REGNO (src
);
4670 /* Subroutine of bypass_block that checks whether a pseudo is killed by
4671 any of the instructions inserted on an edge. Jump bypassing places
4672 condition code setters on CFG edges using insert_insn_on_edge. This
4673 function is required to check that our data flow analysis is still
4674 valid prior to commit_edge_insertions. */
4677 reg_killed_on_edge (rtx reg
, edge e
)
4681 for (insn
= e
->insns
; insn
; insn
= NEXT_INSN (insn
))
4682 if (INSN_P (insn
) && reg_set_p (reg
, insn
))
4688 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
4689 basic block BB which has more than one predecessor. If not NULL, SETCC
4690 is the first instruction of BB, which is immediately followed by JUMP_INSN
4691 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
4692 Returns nonzero if a change was made.
4694 During the jump bypassing pass, we may place copies of SETCC instructions
4695 on CFG edges. The following routine must be careful to pay attention to
4696 these inserted insns when performing its transformations. */
4699 bypass_block (basic_block bb
, rtx setcc
, rtx jump
)
4702 edge e
, enext
, edest
;
4704 int may_be_loop_header
;
4706 insn
= (setcc
!= NULL
) ? setcc
: jump
;
4708 /* Determine set of register uses in INSN. */
4710 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
4711 note
= find_reg_equal_equiv_note (insn
);
4713 find_used_regs (&XEXP (note
, 0), NULL
);
4715 may_be_loop_header
= false;
4716 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
4717 if (e
->flags
& EDGE_DFS_BACK
)
4719 may_be_loop_header
= true;
4724 for (e
= bb
->pred
; e
; e
= enext
)
4726 enext
= e
->pred_next
;
4727 if (e
->flags
& EDGE_COMPLEX
)
4730 /* We can't redirect edges from new basic blocks. */
4731 if (e
->src
->index
>= bypass_last_basic_block
)
4734 /* The irreducible loops created by redirecting of edges entering the
4735 loop from outside would decrease effectiveness of some of the following
4736 optimizations, so prevent this. */
4737 if (may_be_loop_header
4738 && !(e
->flags
& EDGE_DFS_BACK
))
4741 for (i
= 0; i
< reg_use_count
; i
++)
4743 struct reg_use
*reg_used
= ®_use_table
[i
];
4744 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
4745 basic_block dest
, old_dest
;
4749 if (regno
>= max_gcse_regno
)
4752 set
= find_bypass_set (regno
, e
->src
->index
);
4757 /* Check the data flow is valid after edge insertions. */
4758 if (e
->insns
&& reg_killed_on_edge (reg_used
->reg_rtx
, e
))
4761 src
= SET_SRC (pc_set (jump
));
4764 src
= simplify_replace_rtx (src
,
4765 SET_DEST (PATTERN (setcc
)),
4766 SET_SRC (PATTERN (setcc
)));
4768 new = simplify_replace_rtx (src
, reg_used
->reg_rtx
,
4769 SET_SRC (set
->expr
));
4771 /* Jump bypassing may have already placed instructions on
4772 edges of the CFG. We can't bypass an outgoing edge that
4773 has instructions associated with it, as these insns won't
4774 get executed if the incoming edge is redirected. */
4778 edest
= FALLTHRU_EDGE (bb
);
4779 dest
= edest
->insns
? NULL
: edest
->dest
;
4781 else if (GET_CODE (new) == LABEL_REF
)
4783 dest
= BLOCK_FOR_INSN (XEXP (new, 0));
4784 /* Don't bypass edges containing instructions. */
4785 for (edest
= bb
->succ
; edest
; edest
= edest
->succ_next
)
4786 if (edest
->dest
== dest
&& edest
->insns
)
4798 && dest
!= EXIT_BLOCK_PTR
)
4800 redirect_edge_and_branch_force (e
, dest
);
4802 /* Copy the register setter to the redirected edge.
4803 Don't copy CC0 setters, as CC0 is dead after jump. */
4806 rtx pat
= PATTERN (setcc
);
4807 if (!CC0_P (SET_DEST (pat
)))
4808 insert_insn_on_edge (copy_insn (pat
), e
);
4811 if (gcse_file
!= NULL
)
4813 fprintf (gcse_file
, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
4814 regno
, INSN_UID (jump
));
4815 print_rtl (gcse_file
, SET_SRC (set
->expr
));
4816 fprintf (gcse_file
, "\nBypass edge from %d->%d to %d\n",
4817 e
->src
->index
, old_dest
->index
, dest
->index
);
4827 /* Find basic blocks with more than one predecessor that only contain a
4828 single conditional jump. If the result of the comparison is known at
4829 compile-time from any incoming edge, redirect that edge to the
4830 appropriate target. Returns nonzero if a change was made.
4832 This function is now mis-named, because we also handle indirect jumps. */
4835 bypass_conditional_jumps (void)
4843 /* Note we start at block 1. */
4844 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
4847 bypass_last_basic_block
= last_basic_block
;
4848 mark_dfs_back_edges ();
4851 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
,
4852 EXIT_BLOCK_PTR
, next_bb
)
4854 /* Check for more than one predecessor. */
4855 if (bb
->pred
&& bb
->pred
->pred_next
)
4858 for (insn
= bb
->head
;
4859 insn
!= NULL
&& insn
!= NEXT_INSN (bb
->end
);
4860 insn
= NEXT_INSN (insn
))
4861 if (GET_CODE (insn
) == INSN
)
4865 if (GET_CODE (PATTERN (insn
)) != SET
)
4868 dest
= SET_DEST (PATTERN (insn
));
4869 if (REG_P (dest
) || CC0_P (dest
))
4874 else if (GET_CODE (insn
) == JUMP_INSN
)
4876 if ((any_condjump_p (insn
) || computed_jump_p (insn
))
4877 && onlyjump_p (insn
))
4878 changed
|= bypass_block (bb
, setcc
, insn
);
4881 else if (INSN_P (insn
))
4886 /* If we bypassed any register setting insns, we inserted a
4887 copy on the redirected edge. These need to be committed. */
4889 commit_edge_insertions();
4894 /* Compute PRE+LCM working variables. */
4896 /* Local properties of expressions. */
4897 /* Nonzero for expressions that are transparent in the block. */
4898 static sbitmap
*transp
;
4900 /* Nonzero for expressions that are transparent at the end of the block.
4901 This is only zero for expressions killed by abnormal critical edge
4902 created by a calls. */
4903 static sbitmap
*transpout
;
4905 /* Nonzero for expressions that are computed (available) in the block. */
4906 static sbitmap
*comp
;
4908 /* Nonzero for expressions that are locally anticipatable in the block. */
4909 static sbitmap
*antloc
;
4911 /* Nonzero for expressions where this block is an optimal computation
4913 static sbitmap
*pre_optimal
;
4915 /* Nonzero for expressions which are redundant in a particular block. */
4916 static sbitmap
*pre_redundant
;
4918 /* Nonzero for expressions which should be inserted on a specific edge. */
4919 static sbitmap
*pre_insert_map
;
4921 /* Nonzero for expressions which should be deleted in a specific block. */
4922 static sbitmap
*pre_delete_map
;
4924 /* Contains the edge_list returned by pre_edge_lcm. */
4925 static struct edge_list
*edge_list
;
4927 /* Redundant insns. */
4928 static sbitmap pre_redundant_insns
;
4930 /* Allocate vars used for PRE analysis. */
4933 alloc_pre_mem (int n_blocks
, int n_exprs
)
4935 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4936 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4937 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4940 pre_redundant
= NULL
;
4941 pre_insert_map
= NULL
;
4942 pre_delete_map
= NULL
;
4945 ae_kill
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4947 /* pre_insert and pre_delete are allocated later. */
4950 /* Free vars used for PRE analysis. */
4955 sbitmap_vector_free (transp
);
4956 sbitmap_vector_free (comp
);
4958 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
4961 sbitmap_vector_free (pre_optimal
);
4963 sbitmap_vector_free (pre_redundant
);
4965 sbitmap_vector_free (pre_insert_map
);
4967 sbitmap_vector_free (pre_delete_map
);
4969 sbitmap_vector_free (ae_in
);
4971 sbitmap_vector_free (ae_out
);
4973 transp
= comp
= NULL
;
4974 pre_optimal
= pre_redundant
= pre_insert_map
= pre_delete_map
= NULL
;
4975 ae_in
= ae_out
= NULL
;
4978 /* Top level routine to do the dataflow analysis needed by PRE. */
4981 compute_pre_data (void)
4983 sbitmap trapping_expr
;
4987 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
4988 sbitmap_vector_zero (ae_kill
, last_basic_block
);
4990 /* Collect expressions which might trap. */
4991 trapping_expr
= sbitmap_alloc (expr_hash_table
.n_elems
);
4992 sbitmap_zero (trapping_expr
);
4993 for (ui
= 0; ui
< expr_hash_table
.size
; ui
++)
4996 for (e
= expr_hash_table
.table
[ui
]; e
!= NULL
; e
= e
->next_same_hash
)
4997 if (may_trap_p (e
->expr
))
4998 SET_BIT (trapping_expr
, e
->bitmap_index
);
5001 /* Compute ae_kill for each basic block using:
5005 This is significantly faster than compute_ae_kill. */
5011 /* If the current block is the destination of an abnormal edge, we
5012 kill all trapping expressions because we won't be able to properly
5013 place the instruction on the edge. So make them neither
5014 anticipatable nor transparent. This is fairly conservative. */
5015 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
5016 if (e
->flags
& EDGE_ABNORMAL
)
5018 sbitmap_difference (antloc
[bb
->index
], antloc
[bb
->index
], trapping_expr
);
5019 sbitmap_difference (transp
[bb
->index
], transp
[bb
->index
], trapping_expr
);
5023 sbitmap_a_or_b (ae_kill
[bb
->index
], transp
[bb
->index
], comp
[bb
->index
]);
5024 sbitmap_not (ae_kill
[bb
->index
], ae_kill
[bb
->index
]);
5027 edge_list
= pre_edge_lcm (gcse_file
, expr_hash_table
.n_elems
, transp
, comp
, antloc
,
5028 ae_kill
, &pre_insert_map
, &pre_delete_map
);
5029 sbitmap_vector_free (antloc
);
5031 sbitmap_vector_free (ae_kill
);
5033 sbitmap_free (trapping_expr
);
5038 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
5041 VISITED is a pointer to a working buffer for tracking which BB's have
5042 been visited. It is NULL for the top-level call.
5044 We treat reaching expressions that go through blocks containing the same
5045 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
5046 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
5047 2 as not reaching. The intent is to improve the probability of finding
5048 only one reaching expression and to reduce register lifetimes by picking
5049 the closest such expression. */
5052 pre_expr_reaches_here_p_work (basic_block occr_bb
, struct expr
*expr
, basic_block bb
, char *visited
)
5056 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
5058 basic_block pred_bb
= pred
->src
;
5060 if (pred
->src
== ENTRY_BLOCK_PTR
5061 /* Has predecessor has already been visited? */
5062 || visited
[pred_bb
->index
])
5063 ;/* Nothing to do. */
5065 /* Does this predecessor generate this expression? */
5066 else if (TEST_BIT (comp
[pred_bb
->index
], expr
->bitmap_index
))
5068 /* Is this the occurrence we're looking for?
5069 Note that there's only one generating occurrence per block
5070 so we just need to check the block number. */
5071 if (occr_bb
== pred_bb
)
5074 visited
[pred_bb
->index
] = 1;
5076 /* Ignore this predecessor if it kills the expression. */
5077 else if (! TEST_BIT (transp
[pred_bb
->index
], expr
->bitmap_index
))
5078 visited
[pred_bb
->index
] = 1;
5080 /* Neither gen nor kill. */
5083 visited
[pred_bb
->index
] = 1;
5084 if (pre_expr_reaches_here_p_work (occr_bb
, expr
, pred_bb
, visited
))
5089 /* All paths have been checked. */
5093 /* The wrapper for pre_expr_reaches_here_work that ensures that any
5094 memory allocated for that function is returned. */
5097 pre_expr_reaches_here_p (basic_block occr_bb
, struct expr
*expr
, basic_block bb
)
5100 char *visited
= xcalloc (last_basic_block
, 1);
5102 rval
= pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
);
5109 /* Given an expr, generate RTL which we can insert at the end of a BB,
5110 or on an edge. Set the block number of any insns generated to
5114 process_insert_insn (struct expr
*expr
)
5116 rtx reg
= expr
->reaching_reg
;
5117 rtx exp
= copy_rtx (expr
->expr
);
5122 /* If the expression is something that's an operand, like a constant,
5123 just copy it to a register. */
5124 if (general_operand (exp
, GET_MODE (reg
)))
5125 emit_move_insn (reg
, exp
);
5127 /* Otherwise, make a new insn to compute this expression and make sure the
5128 insn will be recognized (this also adds any needed CLOBBERs). Copy the
5129 expression to make sure we don't have any sharing issues. */
5130 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode
, reg
, exp
))))
5139 /* Add EXPR to the end of basic block BB.
5141 This is used by both the PRE and code hoisting.
5143 For PRE, we want to verify that the expr is either transparent
5144 or locally anticipatable in the target block. This check makes
5145 no sense for code hoisting. */
5148 insert_insn_end_bb (struct expr
*expr
, basic_block bb
, int pre
)
5152 rtx reg
= expr
->reaching_reg
;
5153 int regno
= REGNO (reg
);
5156 pat
= process_insert_insn (expr
);
5157 if (pat
== NULL_RTX
|| ! INSN_P (pat
))
5161 while (NEXT_INSN (pat_end
) != NULL_RTX
)
5162 pat_end
= NEXT_INSN (pat_end
);
5164 /* If the last insn is a jump, insert EXPR in front [taking care to
5165 handle cc0, etc. properly]. Similarly we need to care trapping
5166 instructions in presence of non-call exceptions. */
5168 if (GET_CODE (insn
) == JUMP_INSN
5169 || (GET_CODE (insn
) == INSN
5170 && (bb
->succ
->succ_next
|| (bb
->succ
->flags
& EDGE_ABNORMAL
))))
5175 /* It should always be the case that we can put these instructions
5176 anywhere in the basic block with performing PRE optimizations.
5178 if (GET_CODE (insn
) == INSN
&& pre
5179 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
5180 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
5183 /* If this is a jump table, then we can't insert stuff here. Since
5184 we know the previous real insn must be the tablejump, we insert
5185 the new instruction just before the tablejump. */
5186 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
5187 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
5188 insn
= prev_real_insn (insn
);
5191 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
5192 if cc0 isn't set. */
5193 note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
5195 insn
= XEXP (note
, 0);
5198 rtx maybe_cc0_setter
= prev_nonnote_insn (insn
);
5199 if (maybe_cc0_setter
5200 && INSN_P (maybe_cc0_setter
)
5201 && sets_cc0_p (PATTERN (maybe_cc0_setter
)))
5202 insn
= maybe_cc0_setter
;
5205 /* FIXME: What if something in cc0/jump uses value set in new insn? */
5206 new_insn
= emit_insn_before (pat
, insn
);
5209 /* Likewise if the last insn is a call, as will happen in the presence
5210 of exception handling. */
5211 else if (GET_CODE (insn
) == CALL_INSN
5212 && (bb
->succ
->succ_next
|| (bb
->succ
->flags
& EDGE_ABNORMAL
)))
5214 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
5215 we search backward and place the instructions before the first
5216 parameter is loaded. Do this for everyone for consistency and a
5217 presumption that we'll get better code elsewhere as well.
5219 It should always be the case that we can put these instructions
5220 anywhere in the basic block with performing PRE optimizations.
5224 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
5225 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
5228 /* Since different machines initialize their parameter registers
5229 in different orders, assume nothing. Collect the set of all
5230 parameter registers. */
5231 insn
= find_first_parameter_load (insn
, bb
->head
);
5233 /* If we found all the parameter loads, then we want to insert
5234 before the first parameter load.
5236 If we did not find all the parameter loads, then we might have
5237 stopped on the head of the block, which could be a CODE_LABEL.
5238 If we inserted before the CODE_LABEL, then we would be putting
5239 the insn in the wrong basic block. In that case, put the insn
5240 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
5241 while (GET_CODE (insn
) == CODE_LABEL
5242 || NOTE_INSN_BASIC_BLOCK_P (insn
))
5243 insn
= NEXT_INSN (insn
);
5245 new_insn
= emit_insn_before (pat
, insn
);
5248 new_insn
= emit_insn_after (pat
, insn
);
5254 add_label_notes (PATTERN (pat
), new_insn
);
5255 note_stores (PATTERN (pat
), record_set_info
, pat
);
5259 pat
= NEXT_INSN (pat
);
5262 gcse_create_count
++;
5266 fprintf (gcse_file
, "PRE/HOIST: end of bb %d, insn %d, ",
5267 bb
->index
, INSN_UID (new_insn
));
5268 fprintf (gcse_file
, "copying expression %d to reg %d\n",
5269 expr
->bitmap_index
, regno
);
5273 /* Insert partially redundant expressions on edges in the CFG to make
5274 the expressions fully redundant. */
5277 pre_edge_insert (struct edge_list
*edge_list
, struct expr
**index_map
)
5279 int e
, i
, j
, num_edges
, set_size
, did_insert
= 0;
5282 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
5283 if it reaches any of the deleted expressions. */
5285 set_size
= pre_insert_map
[0]->size
;
5286 num_edges
= NUM_EDGES (edge_list
);
5287 inserted
= sbitmap_vector_alloc (num_edges
, expr_hash_table
.n_elems
);
5288 sbitmap_vector_zero (inserted
, num_edges
);
5290 for (e
= 0; e
< num_edges
; e
++)
5293 basic_block bb
= INDEX_EDGE_PRED_BB (edge_list
, e
);
5295 for (i
= indx
= 0; i
< set_size
; i
++, indx
+= SBITMAP_ELT_BITS
)
5297 SBITMAP_ELT_TYPE insert
= pre_insert_map
[e
]->elms
[i
];
5299 for (j
= indx
; insert
&& j
< (int) expr_hash_table
.n_elems
; j
++, insert
>>= 1)
5300 if ((insert
& 1) != 0 && index_map
[j
]->reaching_reg
!= NULL_RTX
)
5302 struct expr
*expr
= index_map
[j
];
5305 /* Now look at each deleted occurrence of this expression. */
5306 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5308 if (! occr
->deleted_p
)
5311 /* Insert this expression on this edge if if it would
5312 reach the deleted occurrence in BB. */
5313 if (!TEST_BIT (inserted
[e
], j
))
5316 edge eg
= INDEX_EDGE (edge_list
, e
);
5318 /* We can't insert anything on an abnormal and
5319 critical edge, so we insert the insn at the end of
5320 the previous block. There are several alternatives
5321 detailed in Morgans book P277 (sec 10.5) for
5322 handling this situation. This one is easiest for
5325 if ((eg
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
5326 insert_insn_end_bb (index_map
[j
], bb
, 0);
5329 insn
= process_insert_insn (index_map
[j
]);
5330 insert_insn_on_edge (insn
, eg
);
5335 fprintf (gcse_file
, "PRE/HOIST: edge (%d,%d), ",
5337 INDEX_EDGE_SUCC_BB (edge_list
, e
)->index
);
5338 fprintf (gcse_file
, "copy expression %d\n",
5339 expr
->bitmap_index
);
5342 update_ld_motion_stores (expr
);
5343 SET_BIT (inserted
[e
], j
);
5345 gcse_create_count
++;
5352 sbitmap_vector_free (inserted
);
5356 /* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
5357 Given "old_reg <- expr" (INSN), instead of adding after it
5358 reaching_reg <- old_reg
5359 it's better to do the following:
5360 reaching_reg <- expr
5361 old_reg <- reaching_reg
5362 because this way copy propagation can discover additional PRE
5363 opportunuties. But if this fails, we try the old way. */
5366 pre_insert_copy_insn (struct expr
*expr
, rtx insn
)
5368 rtx reg
= expr
->reaching_reg
;
5369 int regno
= REGNO (reg
);
5370 int indx
= expr
->bitmap_index
;
5371 rtx pat
= PATTERN (insn
);
5376 /* This block matches the logic in hash_scan_insn. */
5377 if (GET_CODE (pat
) == SET
)
5379 else if (GET_CODE (pat
) == PARALLEL
)
5381 /* Search through the parallel looking for the set whose
5382 source was the expression that we're interested in. */
5384 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
5386 rtx x
= XVECEXP (pat
, 0, i
);
5387 if (GET_CODE (x
) == SET
5388 && expr_equiv_p (SET_SRC (x
), expr
->expr
))
5398 old_reg
= SET_DEST (set
);
5400 /* Check if we can modify the set destination in the original insn. */
5401 if (validate_change (insn
, &SET_DEST (set
), reg
, 0))
5403 new_insn
= gen_move_insn (old_reg
, reg
);
5404 new_insn
= emit_insn_after (new_insn
, insn
);
5406 /* Keep register set table up to date. */
5407 replace_one_set (REGNO (old_reg
), insn
, new_insn
);
5408 record_one_set (regno
, insn
);
5412 new_insn
= gen_move_insn (reg
, old_reg
);
5413 new_insn
= emit_insn_after (new_insn
, insn
);
5415 /* Keep register set table up to date. */
5416 record_one_set (regno
, new_insn
);
5419 gcse_create_count
++;
5423 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
5424 BLOCK_NUM (insn
), INSN_UID (new_insn
), indx
,
5425 INSN_UID (insn
), regno
);
5426 update_ld_motion_stores (expr
);
5429 /* Copy available expressions that reach the redundant expression
5430 to `reaching_reg'. */
5433 pre_insert_copies (void)
5440 /* For each available expression in the table, copy the result to
5441 `reaching_reg' if the expression reaches a deleted one.
5443 ??? The current algorithm is rather brute force.
5444 Need to do some profiling. */
5446 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5447 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5449 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
5450 we don't want to insert a copy here because the expression may not
5451 really be redundant. So only insert an insn if the expression was
5452 deleted. This test also avoids further processing if the
5453 expression wasn't deleted anywhere. */
5454 if (expr
->reaching_reg
== NULL
)
5457 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5459 if (! occr
->deleted_p
)
5462 for (avail
= expr
->avail_occr
; avail
!= NULL
; avail
= avail
->next
)
5464 rtx insn
= avail
->insn
;
5466 /* No need to handle this one if handled already. */
5467 if (avail
->copied_p
)
5470 /* Don't handle this one if it's a redundant one. */
5471 if (TEST_BIT (pre_redundant_insns
, INSN_CUID (insn
)))
5474 /* Or if the expression doesn't reach the deleted one. */
5475 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail
->insn
),
5477 BLOCK_FOR_INSN (occr
->insn
)))
5480 /* Copy the result of avail to reaching_reg. */
5481 pre_insert_copy_insn (expr
, insn
);
5482 avail
->copied_p
= 1;
5488 /* Emit move from SRC to DEST noting the equivalence with expression computed
5491 gcse_emit_move_after (rtx src
, rtx dest
, rtx insn
)
5494 rtx set
= single_set (insn
), set2
;
5498 /* This should never fail since we're creating a reg->reg copy
5499 we've verified to be valid. */
5501 new = emit_insn_after (gen_move_insn (dest
, src
), insn
);
5503 /* Note the equivalence for local CSE pass. */
5504 set2
= single_set (new);
5505 if (!set2
|| !rtx_equal_p (SET_DEST (set2
), dest
))
5507 if ((note
= find_reg_equal_equiv_note (insn
)))
5508 eqv
= XEXP (note
, 0);
5510 eqv
= SET_SRC (set
);
5512 set_unique_reg_note (new, REG_EQUAL
, copy_insn_1 (eqv
));
5517 /* Delete redundant computations.
5518 Deletion is done by changing the insn to copy the `reaching_reg' of
5519 the expression into the result of the SET. It is left to later passes
5520 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
5522 Returns nonzero if a change is made. */
5533 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5534 for (expr
= expr_hash_table
.table
[i
];
5536 expr
= expr
->next_same_hash
)
5538 int indx
= expr
->bitmap_index
;
5540 /* We only need to search antic_occr since we require
5543 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
5545 rtx insn
= occr
->insn
;
5547 basic_block bb
= BLOCK_FOR_INSN (insn
);
5549 /* We only delete insns that have a single_set. */
5550 if (TEST_BIT (pre_delete_map
[bb
->index
], indx
)
5551 && (set
= single_set (insn
)) != 0)
5553 /* Create a pseudo-reg to store the result of reaching
5554 expressions into. Get the mode for the new pseudo from
5555 the mode of the original destination pseudo. */
5556 if (expr
->reaching_reg
== NULL
)
5558 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
5560 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
5562 occr
->deleted_p
= 1;
5563 SET_BIT (pre_redundant_insns
, INSN_CUID (insn
));
5570 "PRE: redundant insn %d (expression %d) in ",
5571 INSN_UID (insn
), indx
);
5572 fprintf (gcse_file
, "bb %d, reaching reg is %d\n",
5573 bb
->index
, REGNO (expr
->reaching_reg
));
5582 /* Perform GCSE optimizations using PRE.
5583 This is called by one_pre_gcse_pass after all the dataflow analysis
5586 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
5587 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
5588 Compiler Design and Implementation.
5590 ??? A new pseudo reg is created to hold the reaching expression. The nice
5591 thing about the classical approach is that it would try to use an existing
5592 reg. If the register can't be adequately optimized [i.e. we introduce
5593 reload problems], one could add a pass here to propagate the new register
5596 ??? We don't handle single sets in PARALLELs because we're [currently] not
5597 able to copy the rest of the parallel when we insert copies to create full
5598 redundancies from partial redundancies. However, there's no reason why we
5599 can't handle PARALLELs in the cases where there are no partial
5606 int did_insert
, changed
;
5607 struct expr
**index_map
;
5610 /* Compute a mapping from expression number (`bitmap_index') to
5611 hash table entry. */
5613 index_map
= xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
5614 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5615 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5616 index_map
[expr
->bitmap_index
] = expr
;
5618 /* Reset bitmap used to track which insns are redundant. */
5619 pre_redundant_insns
= sbitmap_alloc (max_cuid
);
5620 sbitmap_zero (pre_redundant_insns
);
5622 /* Delete the redundant insns first so that
5623 - we know what register to use for the new insns and for the other
5624 ones with reaching expressions
5625 - we know which insns are redundant when we go to create copies */
5627 changed
= pre_delete ();
5629 did_insert
= pre_edge_insert (edge_list
, index_map
);
5631 /* In other places with reaching expressions, copy the expression to the
5632 specially allocated pseudo-reg that reaches the redundant expr. */
5633 pre_insert_copies ();
5636 commit_edge_insertions ();
5641 sbitmap_free (pre_redundant_insns
);
5645 /* Top level routine to perform one PRE GCSE pass.
5647 Return nonzero if a change was made. */
5650 one_pre_gcse_pass (int pass
)
5654 gcse_subst_count
= 0;
5655 gcse_create_count
= 0;
5657 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
5658 add_noreturn_fake_exit_edges ();
5660 compute_ld_motion_mems ();
5662 compute_hash_table (&expr_hash_table
);
5663 trim_ld_motion_mems ();
5665 dump_hash_table (gcse_file
, "Expression", &expr_hash_table
);
5667 if (expr_hash_table
.n_elems
> 0)
5669 alloc_pre_mem (last_basic_block
, expr_hash_table
.n_elems
);
5670 compute_pre_data ();
5671 changed
|= pre_gcse ();
5672 free_edge_list (edge_list
);
5677 remove_fake_edges ();
5678 free_hash_table (&expr_hash_table
);
5682 fprintf (gcse_file
, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
5683 current_function_name
, pass
, bytes_used
);
5684 fprintf (gcse_file
, "%d substs, %d insns created\n",
5685 gcse_subst_count
, gcse_create_count
);
5691 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
5692 If notes are added to an insn which references a CODE_LABEL, the
5693 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
5694 because the following loop optimization pass requires them. */
5696 /* ??? This is very similar to the loop.c add_label_notes function. We
5697 could probably share code here. */
5699 /* ??? If there was a jump optimization pass after gcse and before loop,
5700 then we would not need to do this here, because jump would add the
5701 necessary REG_LABEL notes. */
5704 add_label_notes (rtx x
, rtx insn
)
5706 enum rtx_code code
= GET_CODE (x
);
5710 if (code
== LABEL_REF
&& !LABEL_REF_NONLOCAL_P (x
))
5712 /* This code used to ignore labels that referred to dispatch tables to
5713 avoid flow generating (slightly) worse code.
5715 We no longer ignore such label references (see LABEL_REF handling in
5716 mark_jump_label for additional information). */
5718 REG_NOTES (insn
) = gen_rtx_INSN_LIST (REG_LABEL
, XEXP (x
, 0),
5720 if (LABEL_P (XEXP (x
, 0)))
5721 LABEL_NUSES (XEXP (x
, 0))++;
5725 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
5728 add_label_notes (XEXP (x
, i
), insn
);
5729 else if (fmt
[i
] == 'E')
5730 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5731 add_label_notes (XVECEXP (x
, i
, j
), insn
);
5735 /* Compute transparent outgoing information for each block.
5737 An expression is transparent to an edge unless it is killed by
5738 the edge itself. This can only happen with abnormal control flow,
5739 when the edge is traversed through a call. This happens with
5740 non-local labels and exceptions.
5742 This would not be necessary if we split the edge. While this is
5743 normally impossible for abnormal critical edges, with some effort
5744 it should be possible with exception handling, since we still have
5745 control over which handler should be invoked. But due to increased
5746 EH table sizes, this may not be worthwhile. */
5749 compute_transpout (void)
5755 sbitmap_vector_ones (transpout
, last_basic_block
);
5759 /* Note that flow inserted a nop a the end of basic blocks that
5760 end in call instructions for reasons other than abnormal
5762 if (GET_CODE (bb
->end
) != CALL_INSN
)
5765 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5766 for (expr
= expr_hash_table
.table
[i
]; expr
; expr
= expr
->next_same_hash
)
5767 if (GET_CODE (expr
->expr
) == MEM
)
5769 if (GET_CODE (XEXP (expr
->expr
, 0)) == SYMBOL_REF
5770 && CONSTANT_POOL_ADDRESS_P (XEXP (expr
->expr
, 0)))
5773 /* ??? Optimally, we would use interprocedural alias
5774 analysis to determine if this mem is actually killed
5776 RESET_BIT (transpout
[bb
->index
], expr
->bitmap_index
);
5781 /* Removal of useless null pointer checks */
5783 /* Called via note_stores. X is set by SETTER. If X is a register we must
5784 invalidate nonnull_local and set nonnull_killed. DATA is really a
5785 `null_pointer_info *'.
5787 We ignore hard registers. */
5790 invalidate_nonnull_info (rtx x
, rtx setter ATTRIBUTE_UNUSED
, void *data
)
5793 struct null_pointer_info
*npi
= (struct null_pointer_info
*) data
;
5795 while (GET_CODE (x
) == SUBREG
)
5798 /* Ignore anything that is not a register or is a hard register. */
5799 if (GET_CODE (x
) != REG
5800 || REGNO (x
) < npi
->min_reg
5801 || REGNO (x
) >= npi
->max_reg
)
5804 regno
= REGNO (x
) - npi
->min_reg
;
5806 RESET_BIT (npi
->nonnull_local
[npi
->current_block
->index
], regno
);
5807 SET_BIT (npi
->nonnull_killed
[npi
->current_block
->index
], regno
);
5810 /* Do null-pointer check elimination for the registers indicated in
5811 NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
5812 they are not our responsibility to free. */
5815 delete_null_pointer_checks_1 (unsigned int *block_reg
, sbitmap
*nonnull_avin
,
5816 sbitmap
*nonnull_avout
,
5817 struct null_pointer_info
*npi
)
5819 basic_block bb
, current_block
;
5820 sbitmap
*nonnull_local
= npi
->nonnull_local
;
5821 sbitmap
*nonnull_killed
= npi
->nonnull_killed
;
5822 int something_changed
= 0;
5824 /* Compute local properties, nonnull and killed. A register will have
5825 the nonnull property if at the end of the current block its value is
5826 known to be nonnull. The killed property indicates that somewhere in
5827 the block any information we had about the register is killed.
5829 Note that a register can have both properties in a single block. That
5830 indicates that it's killed, then later in the block a new value is
5832 sbitmap_vector_zero (nonnull_local
, last_basic_block
);
5833 sbitmap_vector_zero (nonnull_killed
, last_basic_block
);
5835 FOR_EACH_BB (current_block
)
5837 rtx insn
, stop_insn
;
5839 /* Set the current block for invalidate_nonnull_info. */
5840 npi
->current_block
= current_block
;
5842 /* Scan each insn in the basic block looking for memory references and
5844 stop_insn
= NEXT_INSN (current_block
->end
);
5845 for (insn
= current_block
->head
;
5847 insn
= NEXT_INSN (insn
))
5852 /* Ignore anything that is not a normal insn. */
5853 if (! INSN_P (insn
))
5856 /* Basically ignore anything that is not a simple SET. We do have
5857 to make sure to invalidate nonnull_local and set nonnull_killed
5858 for such insns though. */
5859 set
= single_set (insn
);
5862 note_stores (PATTERN (insn
), invalidate_nonnull_info
, npi
);
5866 /* See if we've got a usable memory load. We handle it first
5867 in case it uses its address register as a dest (which kills
5868 the nonnull property). */
5869 if (GET_CODE (SET_SRC (set
)) == MEM
5870 && GET_CODE ((reg
= XEXP (SET_SRC (set
), 0))) == REG
5871 && REGNO (reg
) >= npi
->min_reg
5872 && REGNO (reg
) < npi
->max_reg
)
5873 SET_BIT (nonnull_local
[current_block
->index
],
5874 REGNO (reg
) - npi
->min_reg
);
5876 /* Now invalidate stuff clobbered by this insn. */
5877 note_stores (PATTERN (insn
), invalidate_nonnull_info
, npi
);
5879 /* And handle stores, we do these last since any sets in INSN can
5880 not kill the nonnull property if it is derived from a MEM
5881 appearing in a SET_DEST. */
5882 if (GET_CODE (SET_DEST (set
)) == MEM
5883 && GET_CODE ((reg
= XEXP (SET_DEST (set
), 0))) == REG
5884 && REGNO (reg
) >= npi
->min_reg
5885 && REGNO (reg
) < npi
->max_reg
)
5886 SET_BIT (nonnull_local
[current_block
->index
],
5887 REGNO (reg
) - npi
->min_reg
);
5891 /* Now compute global properties based on the local properties. This
5892 is a classic global availability algorithm. */
5893 compute_available (nonnull_local
, nonnull_killed
,
5894 nonnull_avout
, nonnull_avin
);
5896 /* Now look at each bb and see if it ends with a compare of a value
5900 rtx last_insn
= bb
->end
;
5901 rtx condition
, earliest
;
5902 int compare_and_branch
;
5904 /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
5905 since BLOCK_REG[BB] is zero if this block did not end with a
5906 comparison against zero, this condition works. */
5907 if (block_reg
[bb
->index
] < npi
->min_reg
5908 || block_reg
[bb
->index
] >= npi
->max_reg
)
5911 /* LAST_INSN is a conditional jump. Get its condition. */
5912 condition
= get_condition (last_insn
, &earliest
, false);
5914 /* If we can't determine the condition then skip. */
5918 /* Is the register known to have a nonzero value? */
5919 if (!TEST_BIT (nonnull_avout
[bb
->index
], block_reg
[bb
->index
] - npi
->min_reg
))
5922 /* Try to compute whether the compare/branch at the loop end is one or
5923 two instructions. */
5924 if (earliest
== last_insn
)
5925 compare_and_branch
= 1;
5926 else if (earliest
== prev_nonnote_insn (last_insn
))
5927 compare_and_branch
= 2;
5931 /* We know the register in this comparison is nonnull at exit from
5932 this block. We can optimize this comparison. */
5933 if (GET_CODE (condition
) == NE
)
5937 new_jump
= emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn
)),
5939 JUMP_LABEL (new_jump
) = JUMP_LABEL (last_insn
);
5940 LABEL_NUSES (JUMP_LABEL (new_jump
))++;
5941 emit_barrier_after (new_jump
);
5944 something_changed
= 1;
5945 delete_insn (last_insn
);
5946 if (compare_and_branch
== 2)
5947 delete_insn (earliest
);
5948 purge_dead_edges (bb
);
5950 /* Don't check this block again. (Note that BLOCK_END is
5951 invalid here; we deleted the last instruction in the
5953 block_reg
[bb
->index
] = 0;
5956 return something_changed
;
5959 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
5962 This is conceptually similar to global constant/copy propagation and
5963 classic global CSE (it even uses the same dataflow equations as cprop).
5965 If a register is used as memory address with the form (mem (reg)), then we
5966 know that REG can not be zero at that point in the program. Any instruction
5967 which sets REG "kills" this property.
5969 So, if every path leading to a conditional branch has an available memory
5970 reference of that form, then we know the register can not have the value
5971 zero at the conditional branch.
5973 So we merely need to compute the local properties and propagate that data
5974 around the cfg, then optimize where possible.
5976 We run this pass two times. Once before CSE, then again after CSE. This
5977 has proven to be the most profitable approach. It is rare for new
5978 optimization opportunities of this nature to appear after the first CSE
5981 This could probably be integrated with global cprop with a little work. */
5984 delete_null_pointer_checks (rtx f ATTRIBUTE_UNUSED
)
5986 sbitmap
*nonnull_avin
, *nonnull_avout
;
5987 unsigned int *block_reg
;
5991 int max_reg
= max_reg_num ();
5992 struct null_pointer_info npi
;
5993 int something_changed
= 0;
5995 /* If we have only a single block, or it is too expensive, give up. */
5996 if (n_basic_blocks
<= 1
5997 || is_too_expensive (_ ("NULL pointer checks disabled")))
6000 /* We need four bitmaps, each with a bit for each register in each
6002 regs_per_pass
= get_bitmap_width (4, last_basic_block
, max_reg
);
6004 /* Allocate bitmaps to hold local and global properties. */
6005 npi
.nonnull_local
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6006 npi
.nonnull_killed
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6007 nonnull_avin
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6008 nonnull_avout
= sbitmap_vector_alloc (last_basic_block
, regs_per_pass
);
6010 /* Go through the basic blocks, seeing whether or not each block
6011 ends with a conditional branch whose condition is a comparison
6012 against zero. Record the register compared in BLOCK_REG. */
6013 block_reg
= xcalloc (last_basic_block
, sizeof (int));
6016 rtx last_insn
= bb
->end
;
6017 rtx condition
, earliest
, reg
;
6019 /* We only want conditional branches. */
6020 if (GET_CODE (last_insn
) != JUMP_INSN
6021 || !any_condjump_p (last_insn
)
6022 || !onlyjump_p (last_insn
))
6025 /* LAST_INSN is a conditional jump. Get its condition. */
6026 condition
= get_condition (last_insn
, &earliest
, false);
6028 /* If we were unable to get the condition, or it is not an equality
6029 comparison against zero then there's nothing we can do. */
6031 || (GET_CODE (condition
) != NE
&& GET_CODE (condition
) != EQ
)
6032 || GET_CODE (XEXP (condition
, 1)) != CONST_INT
6033 || (XEXP (condition
, 1)
6034 != CONST0_RTX (GET_MODE (XEXP (condition
, 0)))))
6037 /* We must be checking a register against zero. */
6038 reg
= XEXP (condition
, 0);
6039 if (GET_CODE (reg
) != REG
)
6042 block_reg
[bb
->index
] = REGNO (reg
);
6045 /* Go through the algorithm for each block of registers. */
6046 for (reg
= FIRST_PSEUDO_REGISTER
; reg
< max_reg
; reg
+= regs_per_pass
)
6049 npi
.max_reg
= MIN (reg
+ regs_per_pass
, max_reg
);
6050 something_changed
|= delete_null_pointer_checks_1 (block_reg
,
6056 /* Free the table of registers compared at the end of every block. */
6060 sbitmap_vector_free (npi
.nonnull_local
);
6061 sbitmap_vector_free (npi
.nonnull_killed
);
6062 sbitmap_vector_free (nonnull_avin
);
6063 sbitmap_vector_free (nonnull_avout
);
6065 return something_changed
;
6068 /* Code Hoisting variables and subroutines. */
6070 /* Very busy expressions. */
6071 static sbitmap
*hoist_vbein
;
6072 static sbitmap
*hoist_vbeout
;
6074 /* Hoistable expressions. */
6075 static sbitmap
*hoist_exprs
;
6077 /* Dominator bitmaps. */
6078 dominance_info dominators
;
6080 /* ??? We could compute post dominators and run this algorithm in
6081 reverse to perform tail merging, doing so would probably be
6082 more effective than the tail merging code in jump.c.
6084 It's unclear if tail merging could be run in parallel with
6085 code hoisting. It would be nice. */
6087 /* Allocate vars used for code hoisting analysis. */
6090 alloc_code_hoist_mem (int n_blocks
, int n_exprs
)
6092 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6093 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6094 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6096 hoist_vbein
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6097 hoist_vbeout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6098 hoist_exprs
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6099 transpout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
6102 /* Free vars used for code hoisting analysis. */
6105 free_code_hoist_mem (void)
6107 sbitmap_vector_free (antloc
);
6108 sbitmap_vector_free (transp
);
6109 sbitmap_vector_free (comp
);
6111 sbitmap_vector_free (hoist_vbein
);
6112 sbitmap_vector_free (hoist_vbeout
);
6113 sbitmap_vector_free (hoist_exprs
);
6114 sbitmap_vector_free (transpout
);
6116 free_dominance_info (dominators
);
6119 /* Compute the very busy expressions at entry/exit from each block.
6121 An expression is very busy if all paths from a given point
6122 compute the expression. */
6125 compute_code_hoist_vbeinout (void)
6127 int changed
, passes
;
6130 sbitmap_vector_zero (hoist_vbeout
, last_basic_block
);
6131 sbitmap_vector_zero (hoist_vbein
, last_basic_block
);
6140 /* We scan the blocks in the reverse order to speed up
6142 FOR_EACH_BB_REVERSE (bb
)
6144 changed
|= sbitmap_a_or_b_and_c_cg (hoist_vbein
[bb
->index
], antloc
[bb
->index
],
6145 hoist_vbeout
[bb
->index
], transp
[bb
->index
]);
6146 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
6147 sbitmap_intersection_of_succs (hoist_vbeout
[bb
->index
], hoist_vbein
, bb
->index
);
6154 fprintf (gcse_file
, "hoisting vbeinout computation: %d passes\n", passes
);
6157 /* Top level routine to do the dataflow analysis needed by code hoisting. */
6160 compute_code_hoist_data (void)
6162 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
6163 compute_transpout ();
6164 compute_code_hoist_vbeinout ();
6165 dominators
= calculate_dominance_info (CDI_DOMINATORS
);
6167 fprintf (gcse_file
, "\n");
6170 /* Determine if the expression identified by EXPR_INDEX would
6171 reach BB unimpared if it was placed at the end of EXPR_BB.
6173 It's unclear exactly what Muchnick meant by "unimpared". It seems
6174 to me that the expression must either be computed or transparent in
6175 *every* block in the path(s) from EXPR_BB to BB. Any other definition
6176 would allow the expression to be hoisted out of loops, even if
6177 the expression wasn't a loop invariant.
6179 Contrast this to reachability for PRE where an expression is
6180 considered reachable if *any* path reaches instead of *all*
6184 hoist_expr_reaches_here_p (basic_block expr_bb
, int expr_index
, basic_block bb
, char *visited
)
6187 int visited_allocated_locally
= 0;
6190 if (visited
== NULL
)
6192 visited_allocated_locally
= 1;
6193 visited
= xcalloc (last_basic_block
, 1);
6196 for (pred
= bb
->pred
; pred
!= NULL
; pred
= pred
->pred_next
)
6198 basic_block pred_bb
= pred
->src
;
6200 if (pred
->src
== ENTRY_BLOCK_PTR
)
6202 else if (pred_bb
== expr_bb
)
6204 else if (visited
[pred_bb
->index
])
6207 /* Does this predecessor generate this expression? */
6208 else if (TEST_BIT (comp
[pred_bb
->index
], expr_index
))
6210 else if (! TEST_BIT (transp
[pred_bb
->index
], expr_index
))
6216 visited
[pred_bb
->index
] = 1;
6217 if (! hoist_expr_reaches_here_p (expr_bb
, expr_index
,
6222 if (visited_allocated_locally
)
6225 return (pred
== NULL
);
6228 /* Actually perform code hoisting. */
6233 basic_block bb
, dominated
;
6235 unsigned int domby_len
;
6237 struct expr
**index_map
;
6240 sbitmap_vector_zero (hoist_exprs
, last_basic_block
);
6242 /* Compute a mapping from expression number (`bitmap_index') to
6243 hash table entry. */
6245 index_map
= xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
6246 for (i
= 0; i
< expr_hash_table
.size
; i
++)
6247 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
6248 index_map
[expr
->bitmap_index
] = expr
;
6250 /* Walk over each basic block looking for potentially hoistable
6251 expressions, nothing gets hoisted from the entry block. */
6255 int insn_inserted_p
;
6257 domby_len
= get_dominated_by (dominators
, bb
, &domby
);
6258 /* Examine each expression that is very busy at the exit of this
6259 block. These are the potentially hoistable expressions. */
6260 for (i
= 0; i
< hoist_vbeout
[bb
->index
]->n_bits
; i
++)
6264 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
)
6265 && TEST_BIT (transpout
[bb
->index
], i
))
6267 /* We've found a potentially hoistable expression, now
6268 we look at every block BB dominates to see if it
6269 computes the expression. */
6270 for (j
= 0; j
< domby_len
; j
++)
6272 dominated
= domby
[j
];
6273 /* Ignore self dominance. */
6274 if (bb
== dominated
)
6276 /* We've found a dominated block, now see if it computes
6277 the busy expression and whether or not moving that
6278 expression to the "beginning" of that block is safe. */
6279 if (!TEST_BIT (antloc
[dominated
->index
], i
))
6282 /* Note if the expression would reach the dominated block
6283 unimpared if it was placed at the end of BB.
6285 Keep track of how many times this expression is hoistable
6286 from a dominated block into BB. */
6287 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
6291 /* If we found more than one hoistable occurrence of this
6292 expression, then note it in the bitmap of expressions to
6293 hoist. It makes no sense to hoist things which are computed
6294 in only one BB, and doing so tends to pessimize register
6295 allocation. One could increase this value to try harder
6296 to avoid any possible code expansion due to register
6297 allocation issues; however experiments have shown that
6298 the vast majority of hoistable expressions are only movable
6299 from two successors, so raising this threshold is likely
6300 to nullify any benefit we get from code hoisting. */
6303 SET_BIT (hoist_exprs
[bb
->index
], i
);
6308 /* If we found nothing to hoist, then quit now. */
6315 /* Loop over all the hoistable expressions. */
6316 for (i
= 0; i
< hoist_exprs
[bb
->index
]->n_bits
; i
++)
6318 /* We want to insert the expression into BB only once, so
6319 note when we've inserted it. */
6320 insn_inserted_p
= 0;
6322 /* These tests should be the same as the tests above. */
6323 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
))
6325 /* We've found a potentially hoistable expression, now
6326 we look at every block BB dominates to see if it
6327 computes the expression. */
6328 for (j
= 0; j
< domby_len
; j
++)
6330 dominated
= domby
[j
];
6331 /* Ignore self dominance. */
6332 if (bb
== dominated
)
6335 /* We've found a dominated block, now see if it computes
6336 the busy expression and whether or not moving that
6337 expression to the "beginning" of that block is safe. */
6338 if (!TEST_BIT (antloc
[dominated
->index
], i
))
6341 /* The expression is computed in the dominated block and
6342 it would be safe to compute it at the start of the
6343 dominated block. Now we have to determine if the
6344 expression would reach the dominated block if it was
6345 placed at the end of BB. */
6346 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
6348 struct expr
*expr
= index_map
[i
];
6349 struct occr
*occr
= expr
->antic_occr
;
6353 /* Find the right occurrence of this expression. */
6354 while (BLOCK_FOR_INSN (occr
->insn
) != dominated
&& occr
)
6357 /* Should never happen. */
6363 set
= single_set (insn
);
6367 /* Create a pseudo-reg to store the result of reaching
6368 expressions into. Get the mode for the new pseudo
6369 from the mode of the original destination pseudo. */
6370 if (expr
->reaching_reg
== NULL
)
6372 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
6374 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
6376 occr
->deleted_p
= 1;
6377 if (!insn_inserted_p
)
6379 insert_insn_end_bb (index_map
[i
], bb
, 0);
6380 insn_inserted_p
= 1;
6392 /* Top level routine to perform one code hoisting (aka unification) pass
6394 Return nonzero if a change was made. */
6397 one_code_hoisting_pass (void)
6401 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
6402 compute_hash_table (&expr_hash_table
);
6404 dump_hash_table (gcse_file
, "Code Hosting Expressions", &expr_hash_table
);
6406 if (expr_hash_table
.n_elems
> 0)
6408 alloc_code_hoist_mem (last_basic_block
, expr_hash_table
.n_elems
);
6409 compute_code_hoist_data ();
6411 free_code_hoist_mem ();
6414 free_hash_table (&expr_hash_table
);
6419 /* Here we provide the things required to do store motion towards
6420 the exit. In order for this to be effective, gcse also needed to
6421 be taught how to move a load when it is kill only by a store to itself.
6426 void foo(float scale)
6428 for (i=0; i<10; i++)
6432 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
6433 the load out since its live around the loop, and stored at the bottom
6436 The 'Load Motion' referred to and implemented in this file is
6437 an enhancement to gcse which when using edge based lcm, recognizes
6438 this situation and allows gcse to move the load out of the loop.
6440 Once gcse has hoisted the load, store motion can then push this
6441 load towards the exit, and we end up with no loads or stores of 'i'
6444 /* This will search the ldst list for a matching expression. If it
6445 doesn't find one, we create one and initialize it. */
6447 static struct ls_expr
*
6450 struct ls_expr
* ptr
;
6452 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6453 if (expr_equiv_p (ptr
->pattern
, x
))
6458 ptr
= xmalloc (sizeof (struct ls_expr
));
6460 ptr
->next
= pre_ldst_mems
;
6463 ptr
->pattern_regs
= NULL_RTX
;
6464 ptr
->loads
= NULL_RTX
;
6465 ptr
->stores
= NULL_RTX
;
6466 ptr
->reaching_reg
= NULL_RTX
;
6469 ptr
->hash_index
= 0;
6470 pre_ldst_mems
= ptr
;
6476 /* Free up an individual ldst entry. */
6479 free_ldst_entry (struct ls_expr
* ptr
)
6481 free_INSN_LIST_list (& ptr
->loads
);
6482 free_INSN_LIST_list (& ptr
->stores
);
6487 /* Free up all memory associated with the ldst list. */
6490 free_ldst_mems (void)
6492 while (pre_ldst_mems
)
6494 struct ls_expr
* tmp
= pre_ldst_mems
;
6496 pre_ldst_mems
= pre_ldst_mems
->next
;
6498 free_ldst_entry (tmp
);
6501 pre_ldst_mems
= NULL
;
6504 /* Dump debugging info about the ldst list. */
6507 print_ldst_list (FILE * file
)
6509 struct ls_expr
* ptr
;
6511 fprintf (file
, "LDST list: \n");
6513 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6515 fprintf (file
, " Pattern (%3d): ", ptr
->index
);
6517 print_rtl (file
, ptr
->pattern
);
6519 fprintf (file
, "\n Loads : ");
6522 print_rtl (file
, ptr
->loads
);
6524 fprintf (file
, "(nil)");
6526 fprintf (file
, "\n Stores : ");
6529 print_rtl (file
, ptr
->stores
);
6531 fprintf (file
, "(nil)");
6533 fprintf (file
, "\n\n");
6536 fprintf (file
, "\n");
6539 /* Returns 1 if X is in the list of ldst only expressions. */
6541 static struct ls_expr
*
6542 find_rtx_in_ldst (rtx x
)
6544 struct ls_expr
* ptr
;
6546 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
6547 if (expr_equiv_p (ptr
->pattern
, x
) && ! ptr
->invalid
)
6553 /* Assign each element of the list of mems a monotonically increasing value. */
6556 enumerate_ldsts (void)
6558 struct ls_expr
* ptr
;
6561 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
6567 /* Return first item in the list. */
6569 static inline struct ls_expr
*
6570 first_ls_expr (void)
6572 return pre_ldst_mems
;
6575 /* Return the next item in the list after the specified one. */
6577 static inline struct ls_expr
*
6578 next_ls_expr (struct ls_expr
* ptr
)
6583 /* Load Motion for loads which only kill themselves. */
6585 /* Return true if x is a simple MEM operation, with no registers or
6586 side effects. These are the types of loads we consider for the
6587 ld_motion list, otherwise we let the usual aliasing take care of it. */
6592 if (GET_CODE (x
) != MEM
)
6595 if (MEM_VOLATILE_P (x
))
6598 if (GET_MODE (x
) == BLKmode
)
6601 /* If we are handling exceptions, we must be careful with memory references
6602 that may trap. If we are not, the behavior is undefined, so we may just
6604 if (flag_non_call_exceptions
&& may_trap_p (x
))
6607 if (side_effects_p (x
))
6610 /* Do not consider function arguments passed on stack. */
6611 if (reg_mentioned_p (stack_pointer_rtx
, x
))
6614 if (flag_float_store
&& FLOAT_MODE_P (GET_MODE (x
)))
6620 /* Make sure there isn't a buried reference in this pattern anywhere.
6621 If there is, invalidate the entry for it since we're not capable
6622 of fixing it up just yet.. We have to be sure we know about ALL
6623 loads since the aliasing code will allow all entries in the
6624 ld_motion list to not-alias itself. If we miss a load, we will get
6625 the wrong value since gcse might common it and we won't know to
6629 invalidate_any_buried_refs (rtx x
)
6633 struct ls_expr
* ptr
;
6635 /* Invalidate it in the list. */
6636 if (GET_CODE (x
) == MEM
&& simple_mem (x
))
6638 ptr
= ldst_entry (x
);
6642 /* Recursively process the insn. */
6643 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
6645 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0; i
--)
6648 invalidate_any_buried_refs (XEXP (x
, i
));
6649 else if (fmt
[i
] == 'E')
6650 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
6651 invalidate_any_buried_refs (XVECEXP (x
, i
, j
));
6655 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
6656 being defined as MEM loads and stores to symbols, with no side effects
6657 and no registers in the expression. For a MEM destination, we also
6658 check that the insn is still valid if we replace the destination with a
6659 REG, as is done in update_ld_motion_stores. If there are any uses/defs
6660 which don't match this criteria, they are invalidated and trimmed out
6664 compute_ld_motion_mems (void)
6666 struct ls_expr
* ptr
;
6670 pre_ldst_mems
= NULL
;
6674 for (insn
= bb
->head
;
6675 insn
&& insn
!= NEXT_INSN (bb
->end
);
6676 insn
= NEXT_INSN (insn
))
6680 if (GET_CODE (PATTERN (insn
)) == SET
)
6682 rtx src
= SET_SRC (PATTERN (insn
));
6683 rtx dest
= SET_DEST (PATTERN (insn
));
6685 /* Check for a simple LOAD... */
6686 if (GET_CODE (src
) == MEM
&& simple_mem (src
))
6688 ptr
= ldst_entry (src
);
6689 if (GET_CODE (dest
) == REG
)
6690 ptr
->loads
= alloc_INSN_LIST (insn
, ptr
->loads
);
6696 /* Make sure there isn't a buried load somewhere. */
6697 invalidate_any_buried_refs (src
);
6700 /* Check for stores. Don't worry about aliased ones, they
6701 will block any movement we might do later. We only care
6702 about this exact pattern since those are the only
6703 circumstance that we will ignore the aliasing info. */
6704 if (GET_CODE (dest
) == MEM
&& simple_mem (dest
))
6706 ptr
= ldst_entry (dest
);
6708 if (GET_CODE (src
) != MEM
6709 && GET_CODE (src
) != ASM_OPERANDS
6710 /* Check for REG manually since want_to_gcse_p
6711 returns 0 for all REGs. */
6712 && (REG_P (src
) || want_to_gcse_p (src
)))
6713 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
6719 invalidate_any_buried_refs (PATTERN (insn
));
6725 /* Remove any references that have been either invalidated or are not in the
6726 expression list for pre gcse. */
6729 trim_ld_motion_mems (void)
6731 struct ls_expr
* last
= NULL
;
6732 struct ls_expr
* ptr
= first_ls_expr ();
6736 int del
= ptr
->invalid
;
6737 struct expr
* expr
= NULL
;
6739 /* Delete if entry has been made invalid. */
6745 /* Delete if we cannot find this mem in the expression list. */
6746 for (i
= 0; i
< expr_hash_table
.size
&& del
; i
++)
6748 for (expr
= expr_hash_table
.table
[i
];
6750 expr
= expr
->next_same_hash
)
6751 if (expr_equiv_p (expr
->expr
, ptr
->pattern
))
6763 last
->next
= ptr
->next
;
6764 free_ldst_entry (ptr
);
6769 pre_ldst_mems
= pre_ldst_mems
->next
;
6770 free_ldst_entry (ptr
);
6771 ptr
= pre_ldst_mems
;
6776 /* Set the expression field if we are keeping it. */
6783 /* Show the world what we've found. */
6784 if (gcse_file
&& pre_ldst_mems
!= NULL
)
6785 print_ldst_list (gcse_file
);
6788 /* This routine will take an expression which we are replacing with
6789 a reaching register, and update any stores that are needed if
6790 that expression is in the ld_motion list. Stores are updated by
6791 copying their SRC to the reaching register, and then storing
6792 the reaching register into the store location. These keeps the
6793 correct value in the reaching register for the loads. */
6796 update_ld_motion_stores (struct expr
* expr
)
6798 struct ls_expr
* mem_ptr
;
6800 if ((mem_ptr
= find_rtx_in_ldst (expr
->expr
)))
6802 /* We can try to find just the REACHED stores, but is shouldn't
6803 matter to set the reaching reg everywhere... some might be
6804 dead and should be eliminated later. */
6806 /* We replace (set mem expr) with (set reg expr) (set mem reg)
6807 where reg is the reaching reg used in the load. We checked in
6808 compute_ld_motion_mems that we can replace (set mem expr) with
6809 (set reg expr) in that insn. */
6810 rtx list
= mem_ptr
->stores
;
6812 for ( ; list
!= NULL_RTX
; list
= XEXP (list
, 1))
6814 rtx insn
= XEXP (list
, 0);
6815 rtx pat
= PATTERN (insn
);
6816 rtx src
= SET_SRC (pat
);
6817 rtx reg
= expr
->reaching_reg
;
6820 /* If we've already copied it, continue. */
6821 if (expr
->reaching_reg
== src
)
6826 fprintf (gcse_file
, "PRE: store updated with reaching reg ");
6827 print_rtl (gcse_file
, expr
->reaching_reg
);
6828 fprintf (gcse_file
, ":\n ");
6829 print_inline_rtx (gcse_file
, insn
, 8);
6830 fprintf (gcse_file
, "\n");
6833 copy
= gen_move_insn ( reg
, copy_rtx (SET_SRC (pat
)));
6834 new = emit_insn_before (copy
, insn
);
6835 record_one_set (REGNO (reg
), new);
6836 SET_SRC (pat
) = reg
;
6838 /* un-recognize this pattern since it's probably different now. */
6839 INSN_CODE (insn
) = -1;
6840 gcse_create_count
++;
6845 /* Store motion code. */
6847 #define ANTIC_STORE_LIST(x) ((x)->loads)
6848 #define AVAIL_STORE_LIST(x) ((x)->stores)
6849 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
6851 /* This is used to communicate the target bitvector we want to use in the
6852 reg_set_info routine when called via the note_stores mechanism. */
6853 static int * regvec
;
6855 /* And current insn, for the same routine. */
6856 static rtx compute_store_table_current_insn
;
6858 /* Used in computing the reverse edge graph bit vectors. */
6859 static sbitmap
* st_antloc
;
6861 /* Global holding the number of store expressions we are dealing with. */
6862 static int num_stores
;
6864 /* Checks to set if we need to mark a register set. Called from note_stores. */
6867 reg_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
,
6868 void *data ATTRIBUTE_UNUSED
)
6870 if (GET_CODE (dest
) == SUBREG
)
6871 dest
= SUBREG_REG (dest
);
6873 if (GET_CODE (dest
) == REG
)
6874 regvec
[REGNO (dest
)] = INSN_UID (compute_store_table_current_insn
);
6877 /* Return zero if some of the registers in list X are killed
6878 due to set of registers in bitmap REGS_SET. */
6881 store_ops_ok (rtx x
, int *regs_set
)
6885 for (; x
; x
= XEXP (x
, 1))
6888 if (regs_set
[REGNO(reg
)])
6895 /* Returns a list of registers mentioned in X. */
6897 extract_mentioned_regs (rtx x
)
6899 return extract_mentioned_regs_helper (x
, NULL_RTX
);
6902 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
6905 extract_mentioned_regs_helper (rtx x
, rtx accum
)
6911 /* Repeat is used to turn tail-recursion into iteration. */
6917 code
= GET_CODE (x
);
6921 return alloc_EXPR_LIST (0, x
, accum
);
6931 /* We do not run this function with arguments having side effects. */
6950 i
= GET_RTX_LENGTH (code
) - 1;
6951 fmt
= GET_RTX_FORMAT (code
);
6957 rtx tem
= XEXP (x
, i
);
6959 /* If we are about to do the last recursive call
6960 needed at this level, change it into iteration. */
6967 accum
= extract_mentioned_regs_helper (tem
, accum
);
6969 else if (fmt
[i
] == 'E')
6973 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
6974 accum
= extract_mentioned_regs_helper (XVECEXP (x
, i
, j
), accum
);
6981 /* Determine whether INSN is MEM store pattern that we will consider moving.
6982 REGS_SET_BEFORE is bitmap of registers set before (and including) the
6983 current insn, REGS_SET_AFTER is bitmap of registers set after (and
6984 including) the insn in this basic block. We must be passing through BB from
6985 head to end, as we are using this fact to speed things up.
6987 The results are stored this way:
6989 -- the first anticipatable expression is added into ANTIC_STORE_LIST
6990 -- if the processed expression is not anticipatable, NULL_RTX is added
6991 there instead, so that we can use it as indicator that no further
6992 expression of this type may be anticipatable
6993 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
6994 consequently, all of them but this head are dead and may be deleted.
6995 -- if the expression is not available, the insn due to that it fails to be
6996 available is stored in reaching_reg.
6998 The things are complicated a bit by fact that there already may be stores
6999 to the same MEM from other blocks; also caller must take care of the
7000 necessary cleanup of the temporary markers after end of the basic block.
7004 find_moveable_store (rtx insn
, int *regs_set_before
, int *regs_set_after
)
7006 struct ls_expr
* ptr
;
7008 int check_anticipatable
, check_available
;
7009 basic_block bb
= BLOCK_FOR_INSN (insn
);
7011 set
= single_set (insn
);
7015 dest
= SET_DEST (set
);
7017 if (GET_CODE (dest
) != MEM
|| MEM_VOLATILE_P (dest
)
7018 || GET_MODE (dest
) == BLKmode
)
7021 if (side_effects_p (dest
))
7024 /* If we are handling exceptions, we must be careful with memory references
7025 that may trap. If we are not, the behavior is undefined, so we may just
7027 if (flag_non_call_exceptions
&& may_trap_p (dest
))
7030 ptr
= ldst_entry (dest
);
7031 if (!ptr
->pattern_regs
)
7032 ptr
->pattern_regs
= extract_mentioned_regs (dest
);
7034 /* Do not check for anticipatability if we either found one anticipatable
7035 store already, or tested for one and found out that it was killed. */
7036 check_anticipatable
= 0;
7037 if (!ANTIC_STORE_LIST (ptr
))
7038 check_anticipatable
= 1;
7041 tmp
= XEXP (ANTIC_STORE_LIST (ptr
), 0);
7043 && BLOCK_FOR_INSN (tmp
) != bb
)
7044 check_anticipatable
= 1;
7046 if (check_anticipatable
)
7048 if (store_killed_before (dest
, ptr
->pattern_regs
, insn
, bb
, regs_set_before
))
7052 ANTIC_STORE_LIST (ptr
) = alloc_INSN_LIST (tmp
,
7053 ANTIC_STORE_LIST (ptr
));
7056 /* It is not necessary to check whether store is available if we did
7057 it successfully before; if we failed before, do not bother to check
7058 until we reach the insn that caused us to fail. */
7059 check_available
= 0;
7060 if (!AVAIL_STORE_LIST (ptr
))
7061 check_available
= 1;
7064 tmp
= XEXP (AVAIL_STORE_LIST (ptr
), 0);
7065 if (BLOCK_FOR_INSN (tmp
) != bb
)
7066 check_available
= 1;
7068 if (check_available
)
7070 /* Check that we have already reached the insn at that the check
7071 failed last time. */
7072 if (LAST_AVAIL_CHECK_FAILURE (ptr
))
7075 tmp
!= insn
&& tmp
!= LAST_AVAIL_CHECK_FAILURE (ptr
);
7076 tmp
= PREV_INSN (tmp
))
7079 check_available
= 0;
7082 check_available
= store_killed_after (dest
, ptr
->pattern_regs
, insn
,
7084 &LAST_AVAIL_CHECK_FAILURE (ptr
));
7086 if (!check_available
)
7087 AVAIL_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
, AVAIL_STORE_LIST (ptr
));
7090 /* Find available and anticipatable stores. */
7093 compute_store_table (void)
7099 int *last_set_in
, *already_set
;
7100 struct ls_expr
* ptr
, **prev_next_ptr_ptr
;
7102 max_gcse_regno
= max_reg_num ();
7104 reg_set_in_block
= sbitmap_vector_alloc (last_basic_block
,
7106 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
7108 last_set_in
= xmalloc (sizeof (int) * max_gcse_regno
);
7109 already_set
= xmalloc (sizeof (int) * max_gcse_regno
);
7111 /* Find all the stores we care about. */
7114 /* First compute the registers set in this block. */
7115 memset (last_set_in
, 0, sizeof (int) * max_gcse_regno
);
7116 regvec
= last_set_in
;
7118 for (insn
= bb
->head
;
7119 insn
!= NEXT_INSN (bb
->end
);
7120 insn
= NEXT_INSN (insn
))
7122 if (! INSN_P (insn
))
7125 if (GET_CODE (insn
) == CALL_INSN
)
7127 bool clobbers_all
= false;
7128 #ifdef NON_SAVING_SETJMP
7129 if (NON_SAVING_SETJMP
7130 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
7131 clobbers_all
= true;
7134 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
7136 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
7137 last_set_in
[regno
] = INSN_UID (insn
);
7140 pat
= PATTERN (insn
);
7141 compute_store_table_current_insn
= insn
;
7142 note_stores (pat
, reg_set_info
, NULL
);
7145 /* Record the set registers. */
7146 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
7147 if (last_set_in
[regno
])
7148 SET_BIT (reg_set_in_block
[bb
->index
], regno
);
7150 /* Now find the stores. */
7151 memset (already_set
, 0, sizeof (int) * max_gcse_regno
);
7152 regvec
= already_set
;
7153 for (insn
= bb
->head
;
7154 insn
!= NEXT_INSN (bb
->end
);
7155 insn
= NEXT_INSN (insn
))
7157 if (! INSN_P (insn
))
7160 if (GET_CODE (insn
) == CALL_INSN
)
7162 bool clobbers_all
= false;
7163 #ifdef NON_SAVING_SETJMP
7164 if (NON_SAVING_SETJMP
7165 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
7166 clobbers_all
= true;
7169 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
7171 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
7172 already_set
[regno
] = 1;
7175 pat
= PATTERN (insn
);
7176 note_stores (pat
, reg_set_info
, NULL
);
7178 /* Now that we've marked regs, look for stores. */
7179 find_moveable_store (insn
, already_set
, last_set_in
);
7181 /* Unmark regs that are no longer set. */
7182 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
7183 if (last_set_in
[regno
] == INSN_UID (insn
))
7184 last_set_in
[regno
] = 0;
7187 /* Clear temporary marks. */
7188 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7190 LAST_AVAIL_CHECK_FAILURE(ptr
) = NULL_RTX
;
7191 if (ANTIC_STORE_LIST (ptr
)
7192 && (tmp
= XEXP (ANTIC_STORE_LIST (ptr
), 0)) == NULL_RTX
)
7193 ANTIC_STORE_LIST (ptr
) = XEXP (ANTIC_STORE_LIST (ptr
), 1);
7197 /* Remove the stores that are not available anywhere, as there will
7198 be no opportunity to optimize them. */
7199 for (ptr
= pre_ldst_mems
, prev_next_ptr_ptr
= &pre_ldst_mems
;
7201 ptr
= *prev_next_ptr_ptr
)
7203 if (!AVAIL_STORE_LIST (ptr
))
7205 *prev_next_ptr_ptr
= ptr
->next
;
7206 free_ldst_entry (ptr
);
7209 prev_next_ptr_ptr
= &ptr
->next
;
7212 ret
= enumerate_ldsts ();
7216 fprintf (gcse_file
, "ST_avail and ST_antic (shown under loads..)\n");
7217 print_ldst_list (gcse_file
);
7225 /* Check to see if the load X is aliased with STORE_PATTERN.
7226 AFTER is true if we are checking the case when STORE_PATTERN occurs
7230 load_kills_store (rtx x
, rtx store_pattern
, int after
)
7233 return anti_dependence (x
, store_pattern
);
7235 return true_dependence (store_pattern
, GET_MODE (store_pattern
), x
,
7239 /* Go through the entire insn X, looking for any loads which might alias
7240 STORE_PATTERN. Return true if found.
7241 AFTER is true if we are checking the case when STORE_PATTERN occurs
7242 after the insn X. */
7245 find_loads (rtx x
, rtx store_pattern
, int after
)
7254 if (GET_CODE (x
) == SET
)
7257 if (GET_CODE (x
) == MEM
)
7259 if (load_kills_store (x
, store_pattern
, after
))
7263 /* Recursively process the insn. */
7264 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
7266 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0 && !ret
; i
--)
7269 ret
|= find_loads (XEXP (x
, i
), store_pattern
, after
);
7270 else if (fmt
[i
] == 'E')
7271 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
7272 ret
|= find_loads (XVECEXP (x
, i
, j
), store_pattern
, after
);
7277 /* Check if INSN kills the store pattern X (is aliased with it).
7278 AFTER is true if we are checking the case when store X occurs
7279 after the insn. Return true if it it does. */
7282 store_killed_in_insn (rtx x
, rtx x_regs
, rtx insn
, int after
)
7284 rtx reg
, base
, note
;
7289 if (GET_CODE (insn
) == CALL_INSN
)
7291 /* A normal or pure call might read from pattern,
7292 but a const call will not. */
7293 if (! CONST_OR_PURE_CALL_P (insn
) || pure_call_p (insn
))
7296 /* But even a const call reads its parameters. Check whether the
7297 base of some of registers used in mem is stack pointer. */
7298 for (reg
= x_regs
; reg
; reg
= XEXP (reg
, 1))
7300 base
= find_base_term (XEXP (reg
, 0));
7302 || (GET_CODE (base
) == ADDRESS
7303 && GET_MODE (base
) == Pmode
7304 && XEXP (base
, 0) == stack_pointer_rtx
))
7311 if (GET_CODE (PATTERN (insn
)) == SET
)
7313 rtx pat
= PATTERN (insn
);
7314 rtx dest
= SET_DEST (pat
);
7316 if (GET_CODE (dest
) == SIGN_EXTRACT
7317 || GET_CODE (dest
) == ZERO_EXTRACT
)
7318 dest
= XEXP (dest
, 0);
7320 /* Check for memory stores to aliased objects. */
7321 if (GET_CODE (dest
) == MEM
7322 && !expr_equiv_p (dest
, x
))
7326 if (output_dependence (dest
, x
))
7331 if (output_dependence (x
, dest
))
7335 if (find_loads (SET_SRC (pat
), x
, after
))
7338 else if (find_loads (PATTERN (insn
), x
, after
))
7341 /* If this insn has a REG_EQUAL or REG_EQUIV note referencing a memory
7342 location aliased with X, then this insn kills X. */
7343 note
= find_reg_equal_equiv_note (insn
);
7346 note
= XEXP (note
, 0);
7348 /* However, if the note represents a must alias rather than a may
7349 alias relationship, then it does not kill X. */
7350 if (expr_equiv_p (note
, x
))
7353 /* See if there are any aliased loads in the note. */
7354 return find_loads (note
, x
, after
);
7357 /* Returns true if the expression X is loaded or clobbered on or after INSN
7358 within basic block BB. REGS_SET_AFTER is bitmap of registers set in
7359 or after the insn. X_REGS is list of registers mentioned in X. If the store
7360 is killed, return the last insn in that it occurs in FAIL_INSN. */
7363 store_killed_after (rtx x
, rtx x_regs
, rtx insn
, basic_block bb
,
7364 int *regs_set_after
, rtx
*fail_insn
)
7366 rtx last
= bb
->end
, act
;
7368 if (!store_ops_ok (x_regs
, regs_set_after
))
7370 /* We do not know where it will happen. */
7372 *fail_insn
= NULL_RTX
;
7376 /* Scan from the end, so that fail_insn is determined correctly. */
7377 for (act
= last
; act
!= PREV_INSN (insn
); act
= PREV_INSN (act
))
7378 if (store_killed_in_insn (x
, x_regs
, act
, false))
7388 /* Returns true if the expression X is loaded or clobbered on or before INSN
7389 within basic block BB. X_REGS is list of registers mentioned in X.
7390 REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
7392 store_killed_before (rtx x
, rtx x_regs
, rtx insn
, basic_block bb
,
7393 int *regs_set_before
)
7395 rtx first
= bb
->head
;
7397 if (!store_ops_ok (x_regs
, regs_set_before
))
7400 for ( ; insn
!= PREV_INSN (first
); insn
= PREV_INSN (insn
))
7401 if (store_killed_in_insn (x
, x_regs
, insn
, true))
7407 /* Fill in available, anticipatable, transparent and kill vectors in
7408 STORE_DATA, based on lists of available and anticipatable stores. */
7410 build_store_vectors (void)
7413 int *regs_set_in_block
;
7415 struct ls_expr
* ptr
;
7418 /* Build the gen_vector. This is any store in the table which is not killed
7419 by aliasing later in its block. */
7420 ae_gen
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
7421 sbitmap_vector_zero (ae_gen
, last_basic_block
);
7423 st_antloc
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
7424 sbitmap_vector_zero (st_antloc
, last_basic_block
);
7426 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7428 for (st
= AVAIL_STORE_LIST (ptr
); st
!= NULL
; st
= XEXP (st
, 1))
7430 insn
= XEXP (st
, 0);
7431 bb
= BLOCK_FOR_INSN (insn
);
7433 /* If we've already seen an available expression in this block,
7434 we can delete this one (It occurs earlier in the block). We'll
7435 copy the SRC expression to an unused register in case there
7436 are any side effects. */
7437 if (TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
7439 rtx r
= gen_reg_rtx (GET_MODE (ptr
->pattern
));
7441 fprintf (gcse_file
, "Removing redundant store:\n");
7442 replace_store_insn (r
, XEXP (st
, 0), bb
, ptr
);
7445 SET_BIT (ae_gen
[bb
->index
], ptr
->index
);
7448 for (st
= ANTIC_STORE_LIST (ptr
); st
!= NULL
; st
= XEXP (st
, 1))
7450 insn
= XEXP (st
, 0);
7451 bb
= BLOCK_FOR_INSN (insn
);
7452 SET_BIT (st_antloc
[bb
->index
], ptr
->index
);
7456 ae_kill
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
7457 sbitmap_vector_zero (ae_kill
, last_basic_block
);
7459 transp
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
7460 sbitmap_vector_zero (transp
, last_basic_block
);
7461 regs_set_in_block
= xmalloc (sizeof (int) * max_gcse_regno
);
7465 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
7466 regs_set_in_block
[regno
] = TEST_BIT (reg_set_in_block
[bb
->index
], regno
);
7468 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7470 if (store_killed_after (ptr
->pattern
, ptr
->pattern_regs
, bb
->head
,
7471 bb
, regs_set_in_block
, NULL
))
7473 /* It should not be necessary to consider the expression
7474 killed if it is both anticipatable and available. */
7475 if (!TEST_BIT (st_antloc
[bb
->index
], ptr
->index
)
7476 || !TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
7477 SET_BIT (ae_kill
[bb
->index
], ptr
->index
);
7480 SET_BIT (transp
[bb
->index
], ptr
->index
);
7484 free (regs_set_in_block
);
7488 dump_sbitmap_vector (gcse_file
, "st_antloc", "", st_antloc
, last_basic_block
);
7489 dump_sbitmap_vector (gcse_file
, "st_kill", "", ae_kill
, last_basic_block
);
7490 dump_sbitmap_vector (gcse_file
, "Transpt", "", transp
, last_basic_block
);
7491 dump_sbitmap_vector (gcse_file
, "st_avloc", "", ae_gen
, last_basic_block
);
7495 /* Insert an instruction at the beginning of a basic block, and update
7496 the BLOCK_HEAD if needed. */
7499 insert_insn_start_bb (rtx insn
, basic_block bb
)
7501 /* Insert at start of successor block. */
7502 rtx prev
= PREV_INSN (bb
->head
);
7503 rtx before
= bb
->head
;
7506 if (GET_CODE (before
) != CODE_LABEL
7507 && (GET_CODE (before
) != NOTE
7508 || NOTE_LINE_NUMBER (before
) != NOTE_INSN_BASIC_BLOCK
))
7511 if (prev
== bb
->end
)
7513 before
= NEXT_INSN (before
);
7516 insn
= emit_insn_after (insn
, prev
);
7520 fprintf (gcse_file
, "STORE_MOTION insert store at start of BB %d:\n",
7522 print_inline_rtx (gcse_file
, insn
, 6);
7523 fprintf (gcse_file
, "\n");
7527 /* This routine will insert a store on an edge. EXPR is the ldst entry for
7528 the memory reference, and E is the edge to insert it on. Returns nonzero
7529 if an edge insertion was performed. */
7532 insert_store (struct ls_expr
* expr
, edge e
)
7538 /* We did all the deleted before this insert, so if we didn't delete a
7539 store, then we haven't set the reaching reg yet either. */
7540 if (expr
->reaching_reg
== NULL_RTX
)
7543 if (e
->flags
& EDGE_FAKE
)
7546 reg
= expr
->reaching_reg
;
7547 insn
= gen_move_insn (copy_rtx (expr
->pattern
), reg
);
7549 /* If we are inserting this expression on ALL predecessor edges of a BB,
7550 insert it at the start of the BB, and reset the insert bits on the other
7551 edges so we don't try to insert it on the other edges. */
7553 for (tmp
= e
->dest
->pred
; tmp
; tmp
= tmp
->pred_next
)
7554 if (!(tmp
->flags
& EDGE_FAKE
))
7556 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
7557 if (index
== EDGE_INDEX_NO_EDGE
)
7559 if (! TEST_BIT (pre_insert_map
[index
], expr
->index
))
7563 /* If tmp is NULL, we found an insertion on every edge, blank the
7564 insertion vector for these edges, and insert at the start of the BB. */
7565 if (!tmp
&& bb
!= EXIT_BLOCK_PTR
)
7567 for (tmp
= e
->dest
->pred
; tmp
; tmp
= tmp
->pred_next
)
7569 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
7570 RESET_BIT (pre_insert_map
[index
], expr
->index
);
7572 insert_insn_start_bb (insn
, bb
);
7576 /* We can't insert on this edge, so we'll insert at the head of the
7577 successors block. See Morgan, sec 10.5. */
7578 if ((e
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
7580 insert_insn_start_bb (insn
, bb
);
7584 insert_insn_on_edge (insn
, e
);
7588 fprintf (gcse_file
, "STORE_MOTION insert insn on edge (%d, %d):\n",
7589 e
->src
->index
, e
->dest
->index
);
7590 print_inline_rtx (gcse_file
, insn
, 6);
7591 fprintf (gcse_file
, "\n");
7597 /* Remove any REG_EQUAL or REG_EQUIV notes containing a reference to the
7598 memory location in SMEXPR set in basic block BB.
7600 This could be rather expensive. */
7603 remove_reachable_equiv_notes (basic_block bb
, struct ls_expr
*smexpr
)
7605 edge
*stack
= xmalloc (sizeof (edge
) * n_basic_blocks
), act
;
7606 sbitmap visited
= sbitmap_alloc (last_basic_block
);
7608 rtx last
, insn
, note
;
7609 rtx mem
= smexpr
->pattern
;
7611 sbitmap_zero (visited
);
7621 sbitmap_free (visited
);
7624 act
= stack
[--stack_top
];
7628 if (bb
== EXIT_BLOCK_PTR
7629 || TEST_BIT (visited
, bb
->index
)
7630 || TEST_BIT (ae_kill
[bb
->index
], smexpr
->index
))
7632 act
= act
->succ_next
;
7635 SET_BIT (visited
, bb
->index
);
7637 if (TEST_BIT (st_antloc
[bb
->index
], smexpr
->index
))
7639 for (last
= ANTIC_STORE_LIST (smexpr
);
7640 BLOCK_FOR_INSN (XEXP (last
, 0)) != bb
;
7641 last
= XEXP (last
, 1))
7643 last
= XEXP (last
, 0);
7646 last
= NEXT_INSN (bb
->end
);
7648 for (insn
= bb
->head
; insn
!= last
; insn
= NEXT_INSN (insn
))
7651 note
= find_reg_equal_equiv_note (insn
);
7652 if (!note
|| !expr_equiv_p (XEXP (note
, 0), mem
))
7656 fprintf (gcse_file
, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
7658 remove_note (insn
, note
);
7660 act
= act
->succ_next
;
7664 stack
[stack_top
++] = act
;
7670 /* This routine will replace a store with a SET to a specified register. */
7673 replace_store_insn (rtx reg
, rtx del
, basic_block bb
, struct ls_expr
*smexpr
)
7675 rtx insn
, mem
, note
, set
, ptr
;
7677 mem
= smexpr
->pattern
;
7678 insn
= gen_move_insn (reg
, SET_SRC (single_set (del
)));
7679 insn
= emit_insn_after (insn
, del
);
7684 "STORE_MOTION delete insn in BB %d:\n ", bb
->index
);
7685 print_inline_rtx (gcse_file
, del
, 6);
7686 fprintf (gcse_file
, "\nSTORE MOTION replaced with insn:\n ");
7687 print_inline_rtx (gcse_file
, insn
, 6);
7688 fprintf (gcse_file
, "\n");
7691 for (ptr
= ANTIC_STORE_LIST (smexpr
); ptr
; ptr
= XEXP (ptr
, 1))
7692 if (XEXP (ptr
, 0) == del
)
7694 XEXP (ptr
, 0) = insn
;
7699 /* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
7700 they are no longer accurate provided that they are reached by this
7701 definition, so drop them. */
7702 for (; insn
!= NEXT_INSN (bb
->end
); insn
= NEXT_INSN (insn
))
7705 set
= single_set (insn
);
7708 if (expr_equiv_p (SET_DEST (set
), mem
))
7710 note
= find_reg_equal_equiv_note (insn
);
7711 if (!note
|| !expr_equiv_p (XEXP (note
, 0), mem
))
7715 fprintf (gcse_file
, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
7717 remove_note (insn
, note
);
7719 remove_reachable_equiv_notes (bb
, smexpr
);
7723 /* Delete a store, but copy the value that would have been stored into
7724 the reaching_reg for later storing. */
7727 delete_store (struct ls_expr
* expr
, basic_block bb
)
7731 if (expr
->reaching_reg
== NULL_RTX
)
7732 expr
->reaching_reg
= gen_reg_rtx (GET_MODE (expr
->pattern
));
7734 reg
= expr
->reaching_reg
;
7736 for (i
= AVAIL_STORE_LIST (expr
); i
; i
= XEXP (i
, 1))
7739 if (BLOCK_FOR_INSN (del
) == bb
)
7741 /* We know there is only one since we deleted redundant
7742 ones during the available computation. */
7743 replace_store_insn (reg
, del
, bb
, expr
);
7749 /* Free memory used by store motion. */
7752 free_store_memory (void)
7757 sbitmap_vector_free (ae_gen
);
7759 sbitmap_vector_free (ae_kill
);
7761 sbitmap_vector_free (transp
);
7763 sbitmap_vector_free (st_antloc
);
7765 sbitmap_vector_free (pre_insert_map
);
7767 sbitmap_vector_free (pre_delete_map
);
7768 if (reg_set_in_block
)
7769 sbitmap_vector_free (reg_set_in_block
);
7771 ae_gen
= ae_kill
= transp
= st_antloc
= NULL
;
7772 pre_insert_map
= pre_delete_map
= reg_set_in_block
= NULL
;
7775 /* Perform store motion. Much like gcse, except we move expressions the
7776 other way by looking at the flowgraph in reverse. */
7783 struct ls_expr
* ptr
;
7784 int update_flow
= 0;
7788 fprintf (gcse_file
, "before store motion\n");
7789 print_rtl (gcse_file
, get_insns ());
7792 init_alias_analysis ();
7794 /* Find all the available and anticipatable stores. */
7795 num_stores
= compute_store_table ();
7796 if (num_stores
== 0)
7798 sbitmap_vector_free (reg_set_in_block
);
7799 end_alias_analysis ();
7803 /* Now compute kill & transp vectors. */
7804 build_store_vectors ();
7805 add_noreturn_fake_exit_edges ();
7806 connect_infinite_loops_to_exit ();
7808 edge_list
= pre_edge_rev_lcm (gcse_file
, num_stores
, transp
, ae_gen
,
7809 st_antloc
, ae_kill
, &pre_insert_map
,
7812 /* Now we want to insert the new stores which are going to be needed. */
7813 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
7816 if (TEST_BIT (pre_delete_map
[bb
->index
], ptr
->index
))
7817 delete_store (ptr
, bb
);
7819 for (x
= 0; x
< NUM_EDGES (edge_list
); x
++)
7820 if (TEST_BIT (pre_insert_map
[x
], ptr
->index
))
7821 update_flow
|= insert_store (ptr
, INDEX_EDGE (edge_list
, x
));
7825 commit_edge_insertions ();
7827 free_store_memory ();
7828 free_edge_list (edge_list
);
7829 remove_fake_edges ();
7830 end_alias_analysis ();
7834 /* Entry point for jump bypassing optimization pass. */
7837 bypass_jumps (FILE *file
)
7841 /* We do not construct an accurate cfg in functions which call
7842 setjmp, so just punt to be safe. */
7843 if (current_function_calls_setjmp
)
7846 /* For calling dump_foo fns from gdb. */
7847 debug_stderr
= stderr
;
7850 /* Identify the basic block information for this function, including
7851 successors and predecessors. */
7852 max_gcse_regno
= max_reg_num ();
7855 dump_flow_info (file
);
7857 /* Return if there's nothing to do, or it is too expensive */
7858 if (n_basic_blocks
<= 1 || is_too_expensive (_ ("jump bypassing disabled")))
7861 gcc_obstack_init (&gcse_obstack
);
7864 /* We need alias. */
7865 init_alias_analysis ();
7867 /* Record where pseudo-registers are set. This data is kept accurate
7868 during each pass. ??? We could also record hard-reg information here
7869 [since it's unchanging], however it is currently done during hash table
7872 It may be tempting to compute MEM set information here too, but MEM sets
7873 will be subject to code motion one day and thus we need to compute
7874 information about memory sets when we build the hash tables. */
7876 alloc_reg_set_mem (max_gcse_regno
);
7877 compute_sets (get_insns ());
7879 max_gcse_regno
= max_reg_num ();
7880 alloc_gcse_mem (get_insns ());
7881 changed
= one_cprop_pass (1, 1, 1);
7886 fprintf (file
, "BYPASS of %s: %d basic blocks, ",
7887 current_function_name
, n_basic_blocks
);
7888 fprintf (file
, "%d bytes\n\n", bytes_used
);
7891 obstack_free (&gcse_obstack
, NULL
);
7892 free_reg_set_mem ();
7894 /* We are finished with alias. */
7895 end_alias_analysis ();
7896 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
7901 /* Return true if the graph is too expensive to optimize. PASS is the
7902 optimization about to be performed. */
7905 is_too_expensive (const char *pass
)
7907 /* Trying to perform global optimizations on flow graphs which have
7908 a high connectivity will take a long time and is unlikely to be
7909 particularly useful.
7911 In normal circumstances a cfg should have about twice as many
7912 edges as blocks. But we do not want to punish small functions
7913 which have a couple switch statements. Rather than simply
7914 threshold the number of blocks, uses something with a more
7915 graceful degradation. */
7916 if (n_edges
> 20000 + n_basic_blocks
* 4)
7918 if (warn_disabled_optimization
)
7919 warning ("%s: %d basic blocks and %d edges/basic block",
7920 pass
, n_basic_blocks
, n_edges
/ n_basic_blocks
);
7925 /* If allocating memory for the cprop bitmap would take up too much
7926 storage it's better just to disable the optimization. */
7928 * SBITMAP_SET_SIZE (max_reg_num ())
7929 * sizeof (SBITMAP_ELT_TYPE
)) > MAX_GCSE_MEMORY
)
7931 if (warn_disabled_optimization
)
7932 warning ("%s: %d basic blocks and %d registers",
7933 pass
, n_basic_blocks
, max_reg_num ());
7941 #include "gt-gcse.h"