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, 2004
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"
156 #include "hard-reg-set.h"
159 #include "insn-config.h"
161 #include "basic-block.h"
163 #include "function.h"
172 /* Propagate flow information through back edges and thus enable PRE's
173 moving loop invariant calculations out of loops.
175 Originally this tended to create worse overall code, but several
176 improvements during the development of PRE seem to have made following
177 back edges generally a win.
179 Note much of the loop invariant code motion done here would normally
180 be done by loop.c, which has more heuristics for when to move invariants
181 out of loops. At some point we might need to move some of those
182 heuristics into gcse.c. */
184 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
185 are a superset of those done by GCSE.
187 We perform the following steps:
189 1) Compute basic block information.
191 2) Compute table of places where registers are set.
193 3) Perform copy/constant propagation.
195 4) Perform global cse using lazy code motion if not optimizing
196 for size, or code hoisting if we are.
198 5) Perform another pass of copy/constant propagation.
200 Two passes of copy/constant propagation are done because the first one
201 enables more GCSE and the second one helps to clean up the copies that
202 GCSE creates. This is needed more for PRE than for Classic because Classic
203 GCSE will try to use an existing register containing the common
204 subexpression rather than create a new one. This is harder to do for PRE
205 because of the code motion (which Classic GCSE doesn't do).
207 Expressions we are interested in GCSE-ing are of the form
208 (set (pseudo-reg) (expression)).
209 Function want_to_gcse_p says what these are.
211 PRE handles moving invariant expressions out of loops (by treating them as
212 partially redundant).
214 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
215 assignment) based GVN (global value numbering). L. T. Simpson's paper
216 (Rice University) on value numbering is a useful reference for this.
218 **********************
220 We used to support multiple passes but there are diminishing returns in
221 doing so. The first pass usually makes 90% of the changes that are doable.
222 A second pass can make a few more changes made possible by the first pass.
223 Experiments show any further passes don't make enough changes to justify
226 A study of spec92 using an unlimited number of passes:
227 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
228 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
229 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
231 It was found doing copy propagation between each pass enables further
234 PRE is quite expensive in complicated functions because the DFA can take
235 a while to converge. Hence we only perform one pass. The parameter
236 max-gcse-passes can be modified if one wants to experiment.
238 **********************
240 The steps for PRE are:
242 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
244 2) Perform the data flow analysis for PRE.
246 3) Delete the redundant instructions
248 4) Insert the required copies [if any] that make the partially
249 redundant instructions fully redundant.
251 5) For other reaching expressions, insert an instruction to copy the value
252 to a newly created pseudo that will reach the redundant instruction.
254 The deletion is done first so that when we do insertions we
255 know which pseudo reg to use.
257 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
258 argue it is not. The number of iterations for the algorithm to converge
259 is typically 2-4 so I don't view it as that expensive (relatively speaking).
261 PRE GCSE depends heavily on the second CSE pass to clean up the copies
262 we create. To make an expression reach the place where it's redundant,
263 the result of the expression is copied to a new register, and the redundant
264 expression is deleted by replacing it with this new register. Classic GCSE
265 doesn't have this problem as much as it computes the reaching defs of
266 each register in each block and thus can try to use an existing register.
268 **********************
270 A fair bit of simplicity is created by creating small functions for simple
271 tasks, even when the function is only called in one place. This may
272 measurably slow things down [or may not] by creating more function call
273 overhead than is necessary. The source is laid out so that it's trivial
274 to make the affected functions inline so that one can measure what speed
275 up, if any, can be achieved, and maybe later when things settle things can
278 Help stamp out big monolithic functions! */
280 /* GCSE global vars. */
283 static FILE *gcse_file
;
285 /* Note whether or not we should run jump optimization after gcse. We
286 want to do this for two cases.
288 * If we changed any jumps via cprop.
290 * If we added any labels via edge splitting. */
291 static int run_jump_opt_after_gcse
;
293 /* Bitmaps are normally not included in debugging dumps.
294 However it's useful to be able to print them from GDB.
295 We could create special functions for this, but it's simpler to
296 just allow passing stderr to the dump_foo fns. Since stderr can
297 be a macro, we store a copy here. */
298 static FILE *debug_stderr
;
300 /* An obstack for our working variables. */
301 static struct obstack gcse_obstack
;
303 struct reg_use
{rtx reg_rtx
; };
305 /* Hash table of expressions. */
309 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
311 /* Index in the available expression bitmaps. */
313 /* Next entry with the same hash. */
314 struct expr
*next_same_hash
;
315 /* List of anticipatable occurrences in basic blocks in the function.
316 An "anticipatable occurrence" is one that is the first occurrence in the
317 basic block, the operands are not modified in the basic block prior
318 to the occurrence and the output is not used between the start of
319 the block and the occurrence. */
320 struct occr
*antic_occr
;
321 /* List of available occurrence in basic blocks in the function.
322 An "available occurrence" is one that is the last occurrence in the
323 basic block and the operands are not modified by following statements in
324 the basic block [including this insn]. */
325 struct occr
*avail_occr
;
326 /* Non-null if the computation is PRE redundant.
327 The value is the newly created pseudo-reg to record a copy of the
328 expression in all the places that reach the redundant copy. */
332 /* Occurrence of an expression.
333 There is one per basic block. If a pattern appears more than once the
334 last appearance is used [or first for anticipatable expressions]. */
338 /* Next occurrence of this expression. */
340 /* The insn that computes the expression. */
342 /* Nonzero if this [anticipatable] occurrence has been deleted. */
344 /* Nonzero if this [available] occurrence has been copied to
346 /* ??? This is mutually exclusive with deleted_p, so they could share
351 /* Expression and copy propagation hash tables.
352 Each hash table is an array of buckets.
353 ??? It is known that if it were an array of entries, structure elements
354 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
355 not clear whether in the final analysis a sufficient amount of memory would
356 be saved as the size of the available expression bitmaps would be larger
357 [one could build a mapping table without holes afterwards though].
358 Someday I'll perform the computation and figure it out. */
363 This is an array of `expr_hash_table_size' elements. */
366 /* Size of the hash table, in elements. */
369 /* Number of hash table elements. */
370 unsigned int n_elems
;
372 /* Whether the table is expression of copy propagation one. */
376 /* Expression hash table. */
377 static struct hash_table expr_hash_table
;
379 /* Copy propagation hash table. */
380 static struct hash_table set_hash_table
;
382 /* Mapping of uids to cuids.
383 Only real insns get cuids. */
384 static int *uid_cuid
;
386 /* Highest UID in UID_CUID. */
389 /* Get the cuid of an insn. */
390 #ifdef ENABLE_CHECKING
391 #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
393 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
396 /* Number of cuids. */
399 /* Mapping of cuids to insns. */
400 static rtx
*cuid_insn
;
402 /* Get insn from cuid. */
403 #define CUID_INSN(CUID) (cuid_insn[CUID])
405 /* Maximum register number in function prior to doing gcse + 1.
406 Registers created during this pass have regno >= max_gcse_regno.
407 This is named with "gcse" to not collide with global of same name. */
408 static unsigned int max_gcse_regno
;
410 /* Table of registers that are modified.
412 For each register, each element is a list of places where the pseudo-reg
415 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
416 requires knowledge of which blocks kill which regs [and thus could use
417 a bitmap instead of the lists `reg_set_table' uses].
419 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
420 num-regs) [however perhaps it may be useful to keep the data as is]. One
421 advantage of recording things this way is that `reg_set_table' is fairly
422 sparse with respect to pseudo regs but for hard regs could be fairly dense
423 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
424 up functions like compute_transp since in the case of pseudo-regs we only
425 need to iterate over the number of times a pseudo-reg is set, not over the
426 number of basic blocks [clearly there is a bit of a slow down in the cases
427 where a pseudo is set more than once in a block, however it is believed
428 that the net effect is to speed things up]. This isn't done for hard-regs
429 because recording call-clobbered hard-regs in `reg_set_table' at each
430 function call can consume a fair bit of memory, and iterating over
431 hard-regs stored this way in compute_transp will be more expensive. */
433 typedef struct reg_set
435 /* The next setting of this register. */
436 struct reg_set
*next
;
437 /* The insn where it was set. */
441 static reg_set
**reg_set_table
;
443 /* Size of `reg_set_table'.
444 The table starts out at max_gcse_regno + slop, and is enlarged as
446 static int reg_set_table_size
;
448 /* Amount to grow `reg_set_table' by when it's full. */
449 #define REG_SET_TABLE_SLOP 100
451 /* This is a list of expressions which are MEMs and will be used by load
453 Load motion tracks MEMs which aren't killed by
454 anything except itself. (ie, loads and stores to a single location).
455 We can then allow movement of these MEM refs with a little special
456 allowance. (all stores copy the same value to the reaching reg used
457 for the loads). This means all values used to store into memory must have
458 no side effects so we can re-issue the setter value.
459 Store Motion uses this structure as an expression table to track stores
460 which look interesting, and might be moveable towards the exit block. */
464 struct expr
* expr
; /* Gcse expression reference for LM. */
465 rtx pattern
; /* Pattern of this mem. */
466 rtx pattern_regs
; /* List of registers mentioned by the mem. */
467 rtx loads
; /* INSN list of loads seen. */
468 rtx stores
; /* INSN list of stores seen. */
469 struct ls_expr
* next
; /* Next in the list. */
470 int invalid
; /* Invalid for some reason. */
471 int index
; /* If it maps to a bitmap index. */
472 unsigned int hash_index
; /* Index when in a hash table. */
473 rtx reaching_reg
; /* Register to use when re-writing. */
476 /* Array of implicit set patterns indexed by basic block index. */
477 static rtx
*implicit_sets
;
479 /* Head of the list of load/store memory refs. */
480 static struct ls_expr
* pre_ldst_mems
= NULL
;
482 /* Bitmap containing one bit for each register in the program.
483 Used when performing GCSE to track which registers have been set since
484 the start of the basic block. */
485 static regset reg_set_bitmap
;
487 /* For each block, a bitmap of registers set in the block.
488 This is used by compute_transp.
489 It is computed during hash table computation and not by compute_sets
490 as it includes registers added since the last pass (or between cprop and
491 gcse) and it's currently not easy to realloc sbitmap vectors. */
492 static sbitmap
*reg_set_in_block
;
494 /* Array, indexed by basic block number for a list of insns which modify
495 memory within that block. */
496 static rtx
* modify_mem_list
;
497 bitmap modify_mem_list_set
;
499 /* This array parallels modify_mem_list, but is kept canonicalized. */
500 static rtx
* canon_modify_mem_list
;
501 bitmap canon_modify_mem_list_set
;
502 /* Various variables for statistics gathering. */
504 /* Memory used in a pass.
505 This isn't intended to be absolutely precise. Its intent is only
506 to keep an eye on memory usage. */
507 static int bytes_used
;
509 /* GCSE substitutions made. */
510 static int gcse_subst_count
;
511 /* Number of copy instructions created. */
512 static int gcse_create_count
;
513 /* Number of constants propagated. */
514 static int const_prop_count
;
515 /* Number of copys propagated. */
516 static int copy_prop_count
;
518 /* For available exprs */
519 static sbitmap
*ae_kill
, *ae_gen
;
521 /* Objects of this type are passed around by the null-pointer check
523 struct null_pointer_info
525 /* The basic block being processed. */
526 basic_block current_block
;
527 /* The first register to be handled in this pass. */
528 unsigned int min_reg
;
529 /* One greater than the last register to be handled in this pass. */
530 unsigned int max_reg
;
531 sbitmap
*nonnull_local
;
532 sbitmap
*nonnull_killed
;
535 static void compute_can_copy (void);
536 static void *gmalloc (size_t) ATTRIBUTE_MALLOC
;
537 static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC
;
538 static void *grealloc (void *, size_t);
539 static void *gcse_alloc (unsigned long);
540 static void alloc_gcse_mem (rtx
);
541 static void free_gcse_mem (void);
542 static void alloc_reg_set_mem (int);
543 static void free_reg_set_mem (void);
544 static void record_one_set (int, rtx
);
545 static void replace_one_set (int, rtx
, rtx
);
546 static void record_set_info (rtx
, rtx
, void *);
547 static void compute_sets (rtx
);
548 static void hash_scan_insn (rtx
, struct hash_table
*, int);
549 static void hash_scan_set (rtx
, rtx
, struct hash_table
*);
550 static void hash_scan_clobber (rtx
, rtx
, struct hash_table
*);
551 static void hash_scan_call (rtx
, rtx
, struct hash_table
*);
552 static int want_to_gcse_p (rtx
);
553 static bool can_assign_to_reg_p (rtx
);
554 static bool gcse_constant_p (rtx
);
555 static int oprs_unchanged_p (rtx
, rtx
, int);
556 static int oprs_anticipatable_p (rtx
, rtx
);
557 static int oprs_available_p (rtx
, rtx
);
558 static void insert_expr_in_table (rtx
, enum machine_mode
, rtx
, int, int,
559 struct hash_table
*);
560 static void insert_set_in_table (rtx
, rtx
, struct hash_table
*);
561 static unsigned int hash_expr (rtx
, enum machine_mode
, int *, int);
562 static unsigned int hash_expr_1 (rtx
, enum machine_mode
, int *);
563 static unsigned int hash_string_1 (const char *);
564 static unsigned int hash_set (int, int);
565 static int expr_equiv_p (rtx
, rtx
);
566 static void record_last_reg_set_info (rtx
, int);
567 static void record_last_mem_set_info (rtx
);
568 static void record_last_set_info (rtx
, rtx
, void *);
569 static void compute_hash_table (struct hash_table
*);
570 static void alloc_hash_table (int, struct hash_table
*, int);
571 static void free_hash_table (struct hash_table
*);
572 static void compute_hash_table_work (struct hash_table
*);
573 static void dump_hash_table (FILE *, const char *, struct hash_table
*);
574 static struct expr
*lookup_expr (rtx
, struct hash_table
*);
575 static struct expr
*lookup_set (unsigned int, struct hash_table
*);
576 static struct expr
*next_set (unsigned int, struct expr
*);
577 static void reset_opr_set_tables (void);
578 static int oprs_not_set_p (rtx
, rtx
);
579 static void mark_call (rtx
);
580 static void mark_set (rtx
, rtx
);
581 static void mark_clobber (rtx
, rtx
);
582 static void mark_oprs_set (rtx
);
583 static void alloc_cprop_mem (int, int);
584 static void free_cprop_mem (void);
585 static void compute_transp (rtx
, int, sbitmap
*, int);
586 static void compute_transpout (void);
587 static void compute_local_properties (sbitmap
*, sbitmap
*, sbitmap
*,
588 struct hash_table
*);
589 static void compute_cprop_data (void);
590 static void find_used_regs (rtx
*, void *);
591 static int try_replace_reg (rtx
, rtx
, rtx
);
592 static struct expr
*find_avail_set (int, rtx
);
593 static int cprop_jump (basic_block
, rtx
, rtx
, rtx
, rtx
);
594 static void mems_conflict_for_gcse_p (rtx
, rtx
, void *);
595 static int load_killed_in_block_p (basic_block
, int, rtx
, int);
596 static void canon_list_insert (rtx
, rtx
, void *);
597 static int cprop_insn (rtx
, int);
598 static int cprop (int);
599 static void find_implicit_sets (void);
600 static int one_cprop_pass (int, int, int);
601 static bool constprop_register (rtx
, rtx
, rtx
, int);
602 static struct expr
*find_bypass_set (int, int);
603 static bool reg_killed_on_edge (rtx
, edge
);
604 static int bypass_block (basic_block
, rtx
, rtx
);
605 static int bypass_conditional_jumps (void);
606 static void alloc_pre_mem (int, int);
607 static void free_pre_mem (void);
608 static void compute_pre_data (void);
609 static int pre_expr_reaches_here_p (basic_block
, struct expr
*,
611 static void insert_insn_end_bb (struct expr
*, basic_block
, int);
612 static void pre_insert_copy_insn (struct expr
*, rtx
);
613 static void pre_insert_copies (void);
614 static int pre_delete (void);
615 static int pre_gcse (void);
616 static int one_pre_gcse_pass (int);
617 static void add_label_notes (rtx
, rtx
);
618 static void alloc_code_hoist_mem (int, int);
619 static void free_code_hoist_mem (void);
620 static void compute_code_hoist_vbeinout (void);
621 static void compute_code_hoist_data (void);
622 static int hoist_expr_reaches_here_p (basic_block
, int, basic_block
, char *);
623 static void hoist_code (void);
624 static int one_code_hoisting_pass (void);
625 static rtx
process_insert_insn (struct expr
*);
626 static int pre_edge_insert (struct edge_list
*, struct expr
**);
627 static int pre_expr_reaches_here_p_work (basic_block
, struct expr
*,
628 basic_block
, char *);
629 static struct ls_expr
* ldst_entry (rtx
);
630 static void free_ldst_entry (struct ls_expr
*);
631 static void free_ldst_mems (void);
632 static void print_ldst_list (FILE *);
633 static struct ls_expr
* find_rtx_in_ldst (rtx
);
634 static int enumerate_ldsts (void);
635 static inline struct ls_expr
* first_ls_expr (void);
636 static inline struct ls_expr
* next_ls_expr (struct ls_expr
*);
637 static int simple_mem (rtx
);
638 static void invalidate_any_buried_refs (rtx
);
639 static void compute_ld_motion_mems (void);
640 static void trim_ld_motion_mems (void);
641 static void update_ld_motion_stores (struct expr
*);
642 static void reg_set_info (rtx
, rtx
, void *);
643 static void reg_clear_last_set (rtx
, rtx
, void *);
644 static bool store_ops_ok (rtx
, int *);
645 static rtx
extract_mentioned_regs (rtx
);
646 static rtx
extract_mentioned_regs_helper (rtx
, rtx
);
647 static void find_moveable_store (rtx
, int *, int *);
648 static int compute_store_table (void);
649 static bool load_kills_store (rtx
, rtx
, int);
650 static bool find_loads (rtx
, rtx
, int);
651 static bool store_killed_in_insn (rtx
, rtx
, rtx
, int);
652 static bool store_killed_after (rtx
, rtx
, rtx
, basic_block
, int *, rtx
*);
653 static bool store_killed_before (rtx
, rtx
, rtx
, basic_block
, int *);
654 static void build_store_vectors (void);
655 static void insert_insn_start_bb (rtx
, basic_block
);
656 static int insert_store (struct ls_expr
*, edge
);
657 static void remove_reachable_equiv_notes (basic_block
, struct ls_expr
*);
658 static void replace_store_insn (rtx
, rtx
, basic_block
, struct ls_expr
*);
659 static void delete_store (struct ls_expr
*, basic_block
);
660 static void free_store_memory (void);
661 static void store_motion (void);
662 static void free_insn_expr_list_list (rtx
*);
663 static void clear_modify_mem_tables (void);
664 static void free_modify_mem_tables (void);
665 static rtx
gcse_emit_move_after (rtx
, rtx
, rtx
);
666 static void local_cprop_find_used_regs (rtx
*, void *);
667 static bool do_local_cprop (rtx
, rtx
, int, rtx
*);
668 static bool adjust_libcall_notes (rtx
, rtx
, rtx
, rtx
*);
669 static void local_cprop_pass (int);
670 static bool is_too_expensive (const char *);
673 /* Entry point for global common subexpression elimination.
674 F is the first instruction in the function. */
677 gcse_main (rtx f
, FILE *file
)
680 /* Bytes used at start of pass. */
681 int initial_bytes_used
;
682 /* Maximum number of bytes used by a pass. */
684 /* Point to release obstack data from for each pass. */
685 char *gcse_obstack_bottom
;
687 /* We do not construct an accurate cfg in functions which call
688 setjmp, so just punt to be safe. */
689 if (current_function_calls_setjmp
)
692 /* Assume that we do not need to run jump optimizations after gcse. */
693 run_jump_opt_after_gcse
= 0;
695 /* For calling dump_foo fns from gdb. */
696 debug_stderr
= stderr
;
699 /* Identify the basic block information for this function, including
700 successors and predecessors. */
701 max_gcse_regno
= max_reg_num ();
704 dump_flow_info (file
);
706 /* Return if there's nothing to do, or it is too expensive. */
707 if (n_basic_blocks
<= 1 || is_too_expensive (_("GCSE disabled")))
710 gcc_obstack_init (&gcse_obstack
);
714 init_alias_analysis ();
715 /* Record where pseudo-registers are set. This data is kept accurate
716 during each pass. ??? We could also record hard-reg information here
717 [since it's unchanging], however it is currently done during hash table
720 It may be tempting to compute MEM set information here too, but MEM sets
721 will be subject to code motion one day and thus we need to compute
722 information about memory sets when we build the hash tables. */
724 alloc_reg_set_mem (max_gcse_regno
);
728 initial_bytes_used
= bytes_used
;
730 gcse_obstack_bottom
= gcse_alloc (1);
732 while (changed
&& pass
< MAX_GCSE_PASSES
)
736 fprintf (file
, "GCSE pass %d\n\n", pass
+ 1);
738 /* Initialize bytes_used to the space for the pred/succ lists,
739 and the reg_set_table data. */
740 bytes_used
= initial_bytes_used
;
742 /* Each pass may create new registers, so recalculate each time. */
743 max_gcse_regno
= max_reg_num ();
747 /* Don't allow constant propagation to modify jumps
749 changed
= one_cprop_pass (pass
+ 1, 0, 0);
755 changed
|= one_pre_gcse_pass (pass
+ 1);
756 /* We may have just created new basic blocks. Release and
757 recompute various things which are sized on the number of
761 free_modify_mem_tables ();
762 modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
763 canon_modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
766 alloc_reg_set_mem (max_reg_num ());
768 run_jump_opt_after_gcse
= 1;
771 if (max_pass_bytes
< bytes_used
)
772 max_pass_bytes
= bytes_used
;
774 /* Free up memory, then reallocate for code hoisting. We can
775 not re-use the existing allocated memory because the tables
776 will not have info for the insns or registers created by
777 partial redundancy elimination. */
780 /* It does not make sense to run code hoisting unless we are optimizing
781 for code size -- it rarely makes programs faster, and can make
782 them bigger if we did partial redundancy elimination (when optimizing
783 for space, we don't run the partial redundancy algorithms). */
786 max_gcse_regno
= max_reg_num ();
788 changed
|= one_code_hoisting_pass ();
791 if (max_pass_bytes
< bytes_used
)
792 max_pass_bytes
= bytes_used
;
797 fprintf (file
, "\n");
801 obstack_free (&gcse_obstack
, gcse_obstack_bottom
);
805 /* Do one last pass of copy propagation, including cprop into
806 conditional jumps. */
808 max_gcse_regno
= max_reg_num ();
810 /* This time, go ahead and allow cprop to alter jumps. */
811 one_cprop_pass (pass
+ 1, 1, 0);
816 fprintf (file
, "GCSE of %s: %d basic blocks, ",
817 current_function_name (), n_basic_blocks
);
818 fprintf (file
, "%d pass%s, %d bytes\n\n",
819 pass
, pass
> 1 ? "es" : "", max_pass_bytes
);
822 obstack_free (&gcse_obstack
, NULL
);
825 /* We are finished with alias. */
826 end_alias_analysis ();
827 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
829 if (!optimize_size
&& flag_gcse_sm
)
832 /* Record where pseudo-registers are set. */
833 return run_jump_opt_after_gcse
;
836 /* Misc. utilities. */
838 /* Nonzero for each mode that supports (set (reg) (reg)).
839 This is trivially true for integer and floating point values.
840 It may or may not be true for condition codes. */
841 static char can_copy
[(int) NUM_MACHINE_MODES
];
843 /* Compute which modes support reg/reg copy operations. */
846 compute_can_copy (void)
849 #ifndef AVOID_CCMODE_COPIES
852 memset (can_copy
, 0, NUM_MACHINE_MODES
);
855 for (i
= 0; i
< NUM_MACHINE_MODES
; i
++)
856 if (GET_MODE_CLASS (i
) == MODE_CC
)
858 #ifdef AVOID_CCMODE_COPIES
861 reg
= gen_rtx_REG ((enum machine_mode
) i
, LAST_VIRTUAL_REGISTER
+ 1);
862 insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, reg
));
863 if (recog (PATTERN (insn
), insn
, NULL
) >= 0)
873 /* Returns whether the mode supports reg/reg copy operations. */
876 can_copy_p (enum machine_mode mode
)
878 static bool can_copy_init_p
= false;
880 if (! can_copy_init_p
)
883 can_copy_init_p
= true;
886 return can_copy
[mode
] != 0;
889 /* Cover function to xmalloc to record bytes allocated. */
892 gmalloc (size_t size
)
895 return xmalloc (size
);
898 /* Cover function to xcalloc to record bytes allocated. */
901 gcalloc (size_t nelem
, size_t elsize
)
903 bytes_used
+= nelem
* elsize
;
904 return xcalloc (nelem
, elsize
);
907 /* Cover function to xrealloc.
908 We don't record the additional size since we don't know it.
909 It won't affect memory usage stats much anyway. */
912 grealloc (void *ptr
, size_t size
)
914 return xrealloc (ptr
, size
);
917 /* Cover function to obstack_alloc. */
920 gcse_alloc (unsigned long size
)
923 return obstack_alloc (&gcse_obstack
, size
);
926 /* Allocate memory for the cuid mapping array,
927 and reg/memory set tracking tables.
929 This is called at the start of each pass. */
932 alloc_gcse_mem (rtx f
)
937 /* Find the largest UID and create a mapping from UIDs to CUIDs.
938 CUIDs are like UIDs except they increase monotonically, have no gaps,
939 and only apply to real insns. */
941 max_uid
= get_max_uid ();
942 uid_cuid
= gcalloc (max_uid
+ 1, sizeof (int));
943 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
946 uid_cuid
[INSN_UID (insn
)] = i
++;
948 uid_cuid
[INSN_UID (insn
)] = i
;
951 /* Create a table mapping cuids to insns. */
954 cuid_insn
= gcalloc (max_cuid
+ 1, sizeof (rtx
));
955 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
957 CUID_INSN (i
++) = insn
;
959 /* Allocate vars to track sets of regs. */
960 reg_set_bitmap
= BITMAP_XMALLOC ();
962 /* Allocate vars to track sets of regs, memory per block. */
963 reg_set_in_block
= sbitmap_vector_alloc (last_basic_block
, max_gcse_regno
);
964 /* Allocate array to keep a list of insns which modify memory in each
966 modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
967 canon_modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
968 modify_mem_list_set
= BITMAP_XMALLOC ();
969 canon_modify_mem_list_set
= BITMAP_XMALLOC ();
972 /* Free memory allocated by alloc_gcse_mem. */
980 BITMAP_XFREE (reg_set_bitmap
);
982 sbitmap_vector_free (reg_set_in_block
);
983 free_modify_mem_tables ();
984 BITMAP_XFREE (modify_mem_list_set
);
985 BITMAP_XFREE (canon_modify_mem_list_set
);
988 /* Compute the local properties of each recorded expression.
990 Local properties are those that are defined by the block, irrespective of
993 An expression is transparent in a block if its operands are not modified
996 An expression is computed (locally available) in a block if it is computed
997 at least once and expression would contain the same value if the
998 computation was moved to the end of the block.
1000 An expression is locally anticipatable in a block if it is computed at
1001 least once and expression would contain the same value if the computation
1002 was moved to the beginning of the block.
1004 We call this routine for cprop, pre and code hoisting. They all compute
1005 basically the same information and thus can easily share this code.
1007 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1008 properties. If NULL, then it is not necessary to compute or record that
1009 particular property.
1011 TABLE controls which hash table to look at. If it is set hash table,
1012 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1016 compute_local_properties (sbitmap
*transp
, sbitmap
*comp
, sbitmap
*antloc
,
1017 struct hash_table
*table
)
1021 /* Initialize any bitmaps that were passed in. */
1025 sbitmap_vector_zero (transp
, last_basic_block
);
1027 sbitmap_vector_ones (transp
, last_basic_block
);
1031 sbitmap_vector_zero (comp
, last_basic_block
);
1033 sbitmap_vector_zero (antloc
, last_basic_block
);
1035 for (i
= 0; i
< table
->size
; i
++)
1039 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1041 int indx
= expr
->bitmap_index
;
1044 /* The expression is transparent in this block if it is not killed.
1045 We start by assuming all are transparent [none are killed], and
1046 then reset the bits for those that are. */
1048 compute_transp (expr
->expr
, indx
, transp
, table
->set_p
);
1050 /* The occurrences recorded in antic_occr are exactly those that
1051 we want to set to nonzero in ANTLOC. */
1053 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
1055 SET_BIT (antloc
[BLOCK_NUM (occr
->insn
)], indx
);
1057 /* While we're scanning the table, this is a good place to
1059 occr
->deleted_p
= 0;
1062 /* The occurrences recorded in avail_occr are exactly those that
1063 we want to set to nonzero in COMP. */
1065 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
1067 SET_BIT (comp
[BLOCK_NUM (occr
->insn
)], indx
);
1069 /* While we're scanning the table, this is a good place to
1074 /* While we're scanning the table, this is a good place to
1076 expr
->reaching_reg
= 0;
1081 /* Register set information.
1083 `reg_set_table' records where each register is set or otherwise
1086 static struct obstack reg_set_obstack
;
1089 alloc_reg_set_mem (int n_regs
)
1091 reg_set_table_size
= n_regs
+ REG_SET_TABLE_SLOP
;
1092 reg_set_table
= gcalloc (reg_set_table_size
, sizeof (struct reg_set
*));
1094 gcc_obstack_init (®_set_obstack
);
1098 free_reg_set_mem (void)
1100 free (reg_set_table
);
1101 obstack_free (®_set_obstack
, NULL
);
1104 /* An OLD_INSN that used to set REGNO was replaced by NEW_INSN.
1105 Update the corresponding `reg_set_table' entry accordingly.
1106 We assume that NEW_INSN is not already recorded in reg_set_table[regno]. */
1109 replace_one_set (int regno
, rtx old_insn
, rtx new_insn
)
1111 struct reg_set
*reg_info
;
1112 if (regno
>= reg_set_table_size
)
1114 for (reg_info
= reg_set_table
[regno
]; reg_info
; reg_info
= reg_info
->next
)
1115 if (reg_info
->insn
== old_insn
)
1117 reg_info
->insn
= new_insn
;
1122 /* Record REGNO in the reg_set table. */
1125 record_one_set (int regno
, rtx insn
)
1127 /* Allocate a new reg_set element and link it onto the list. */
1128 struct reg_set
*new_reg_info
;
1130 /* If the table isn't big enough, enlarge it. */
1131 if (regno
>= reg_set_table_size
)
1133 int new_size
= regno
+ REG_SET_TABLE_SLOP
;
1135 reg_set_table
= grealloc (reg_set_table
,
1136 new_size
* sizeof (struct reg_set
*));
1137 memset (reg_set_table
+ reg_set_table_size
, 0,
1138 (new_size
- reg_set_table_size
) * sizeof (struct reg_set
*));
1139 reg_set_table_size
= new_size
;
1142 new_reg_info
= obstack_alloc (®_set_obstack
, sizeof (struct reg_set
));
1143 bytes_used
+= sizeof (struct reg_set
);
1144 new_reg_info
->insn
= insn
;
1145 new_reg_info
->next
= reg_set_table
[regno
];
1146 reg_set_table
[regno
] = new_reg_info
;
1149 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1150 an insn. The DATA is really the instruction in which the SET is
1154 record_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
, void *data
)
1156 rtx record_set_insn
= (rtx
) data
;
1158 if (REG_P (dest
) && REGNO (dest
) >= FIRST_PSEUDO_REGISTER
)
1159 record_one_set (REGNO (dest
), record_set_insn
);
1162 /* Scan the function and record each set of each pseudo-register.
1164 This is called once, at the start of the gcse pass. See the comments for
1165 `reg_set_table' for further documentation. */
1168 compute_sets (rtx f
)
1172 for (insn
= f
; insn
!= 0; insn
= NEXT_INSN (insn
))
1174 note_stores (PATTERN (insn
), record_set_info
, insn
);
1177 /* Hash table support. */
1179 struct reg_avail_info
1181 basic_block last_bb
;
1186 static struct reg_avail_info
*reg_avail_info
;
1187 static basic_block current_bb
;
1190 /* See whether X, the source of a set, is something we want to consider for
1194 want_to_gcse_p (rtx x
)
1196 switch (GET_CODE (x
))
1207 return can_assign_to_reg_p (x
);
1211 /* Used internally by can_assign_to_reg_p. */
1213 static GTY(()) rtx test_insn
;
1215 /* Return true if we can assign X to a pseudo register. */
1218 can_assign_to_reg_p (rtx x
)
1220 int num_clobbers
= 0;
1223 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1224 if (general_operand (x
, GET_MODE (x
)))
1226 else if (GET_MODE (x
) == VOIDmode
)
1229 /* Otherwise, check if we can make a valid insn from it. First initialize
1230 our test insn if we haven't already. */
1234 = make_insn_raw (gen_rtx_SET (VOIDmode
,
1235 gen_rtx_REG (word_mode
,
1236 FIRST_PSEUDO_REGISTER
* 2),
1238 NEXT_INSN (test_insn
) = PREV_INSN (test_insn
) = 0;
1241 /* Now make an insn like the one we would make when GCSE'ing and see if
1243 PUT_MODE (SET_DEST (PATTERN (test_insn
)), GET_MODE (x
));
1244 SET_SRC (PATTERN (test_insn
)) = x
;
1245 return ((icode
= recog (PATTERN (test_insn
), test_insn
, &num_clobbers
)) >= 0
1246 && (num_clobbers
== 0 || ! added_clobbers_hard_reg_p (icode
)));
1249 /* Return nonzero if the operands of expression X are unchanged from the
1250 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1251 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1254 oprs_unchanged_p (rtx x
, rtx insn
, int avail_p
)
1263 code
= GET_CODE (x
);
1268 struct reg_avail_info
*info
= ®_avail_info
[REGNO (x
)];
1270 if (info
->last_bb
!= current_bb
)
1273 return info
->last_set
< INSN_CUID (insn
);
1275 return info
->first_set
>= INSN_CUID (insn
);
1279 if (load_killed_in_block_p (current_bb
, INSN_CUID (insn
),
1283 return oprs_unchanged_p (XEXP (x
, 0), insn
, avail_p
);
1309 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1313 /* If we are about to do the last recursive call needed at this
1314 level, change it into iteration. This function is called enough
1317 return oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
);
1319 else if (! oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
))
1322 else if (fmt
[i
] == 'E')
1323 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1324 if (! oprs_unchanged_p (XVECEXP (x
, i
, j
), insn
, avail_p
))
1331 /* Used for communication between mems_conflict_for_gcse_p and
1332 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1333 conflict between two memory references. */
1334 static int gcse_mems_conflict_p
;
1336 /* Used for communication between mems_conflict_for_gcse_p and
1337 load_killed_in_block_p. A memory reference for a load instruction,
1338 mems_conflict_for_gcse_p will see if a memory store conflicts with
1339 this memory load. */
1340 static rtx gcse_mem_operand
;
1342 /* DEST is the output of an instruction. If it is a memory reference, and
1343 possibly conflicts with the load found in gcse_mem_operand, then set
1344 gcse_mems_conflict_p to a nonzero value. */
1347 mems_conflict_for_gcse_p (rtx dest
, rtx setter ATTRIBUTE_UNUSED
,
1348 void *data ATTRIBUTE_UNUSED
)
1350 while (GET_CODE (dest
) == SUBREG
1351 || GET_CODE (dest
) == ZERO_EXTRACT
1352 || GET_CODE (dest
) == SIGN_EXTRACT
1353 || GET_CODE (dest
) == STRICT_LOW_PART
)
1354 dest
= XEXP (dest
, 0);
1356 /* If DEST is not a MEM, then it will not conflict with the load. Note
1357 that function calls are assumed to clobber memory, but are handled
1362 /* If we are setting a MEM in our list of specially recognized MEMs,
1363 don't mark as killed this time. */
1365 if (expr_equiv_p (dest
, gcse_mem_operand
) && pre_ldst_mems
!= NULL
)
1367 if (!find_rtx_in_ldst (dest
))
1368 gcse_mems_conflict_p
= 1;
1372 if (true_dependence (dest
, GET_MODE (dest
), gcse_mem_operand
,
1374 gcse_mems_conflict_p
= 1;
1377 /* Return nonzero if the expression in X (a memory reference) is killed
1378 in block BB before or after the insn with the CUID in UID_LIMIT.
1379 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1382 To check the entire block, set UID_LIMIT to max_uid + 1 and
1386 load_killed_in_block_p (basic_block bb
, int uid_limit
, rtx x
, int avail_p
)
1388 rtx list_entry
= modify_mem_list
[bb
->index
];
1392 /* Ignore entries in the list that do not apply. */
1394 && INSN_CUID (XEXP (list_entry
, 0)) < uid_limit
)
1396 && INSN_CUID (XEXP (list_entry
, 0)) > uid_limit
))
1398 list_entry
= XEXP (list_entry
, 1);
1402 setter
= XEXP (list_entry
, 0);
1404 /* If SETTER is a call everything is clobbered. Note that calls
1405 to pure functions are never put on the list, so we need not
1406 worry about them. */
1407 if (CALL_P (setter
))
1410 /* SETTER must be an INSN of some kind that sets memory. Call
1411 note_stores to examine each hunk of memory that is modified.
1413 The note_stores interface is pretty limited, so we have to
1414 communicate via global variables. Yuk. */
1415 gcse_mem_operand
= x
;
1416 gcse_mems_conflict_p
= 0;
1417 note_stores (PATTERN (setter
), mems_conflict_for_gcse_p
, NULL
);
1418 if (gcse_mems_conflict_p
)
1420 list_entry
= XEXP (list_entry
, 1);
1425 /* Return nonzero if the operands of expression X are unchanged from
1426 the start of INSN's basic block up to but not including INSN. */
1429 oprs_anticipatable_p (rtx x
, rtx insn
)
1431 return oprs_unchanged_p (x
, insn
, 0);
1434 /* Return nonzero if the operands of expression X are unchanged from
1435 INSN to the end of INSN's basic block. */
1438 oprs_available_p (rtx x
, rtx insn
)
1440 return oprs_unchanged_p (x
, insn
, 1);
1443 /* Hash expression X.
1445 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1446 indicating if a volatile operand is found or if the expression contains
1447 something we don't want to insert in the table. HASH_TABLE_SIZE is
1448 the current size of the hash table to be probed.
1450 ??? One might want to merge this with canon_hash. Later. */
1453 hash_expr (rtx x
, enum machine_mode mode
, int *do_not_record_p
,
1454 int hash_table_size
)
1458 *do_not_record_p
= 0;
1460 hash
= hash_expr_1 (x
, mode
, do_not_record_p
);
1461 return hash
% hash_table_size
;
1464 /* Hash a string. Just add its bytes up. */
1466 static inline unsigned
1467 hash_string_1 (const char *ps
)
1470 const unsigned char *p
= (const unsigned char *) ps
;
1479 /* Subroutine of hash_expr to do the actual work. */
1482 hash_expr_1 (rtx x
, enum machine_mode mode
, int *do_not_record_p
)
1492 /* Used to turn recursion into iteration. We can't rely on GCC's
1493 tail-recursion elimination since we need to keep accumulating values
1497 code
= GET_CODE (x
);
1501 hash
+= ((unsigned int) REG
<< 7) + REGNO (x
);
1505 hash
+= (((unsigned int) CONST_INT
<< 7) + (unsigned int) mode
1506 + (unsigned int) INTVAL (x
));
1510 /* This is like the general case, except that it only counts
1511 the integers representing the constant. */
1512 hash
+= (unsigned int) code
+ (unsigned int) GET_MODE (x
);
1513 if (GET_MODE (x
) != VOIDmode
)
1514 for (i
= 2; i
< GET_RTX_LENGTH (CONST_DOUBLE
); i
++)
1515 hash
+= (unsigned int) XWINT (x
, i
);
1517 hash
+= ((unsigned int) CONST_DOUBLE_LOW (x
)
1518 + (unsigned int) CONST_DOUBLE_HIGH (x
));
1526 units
= CONST_VECTOR_NUNITS (x
);
1528 for (i
= 0; i
< units
; ++i
)
1530 elt
= CONST_VECTOR_ELT (x
, i
);
1531 hash
+= hash_expr_1 (elt
, GET_MODE (elt
), do_not_record_p
);
1537 /* Assume there is only one rtx object for any given label. */
1539 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1540 differences and differences between each stage's debugging dumps. */
1541 hash
+= (((unsigned int) LABEL_REF
<< 7)
1542 + CODE_LABEL_NUMBER (XEXP (x
, 0)));
1547 /* Don't hash on the symbol's address to avoid bootstrap differences.
1548 Different hash values may cause expressions to be recorded in
1549 different orders and thus different registers to be used in the
1550 final assembler. This also avoids differences in the dump files
1551 between various stages. */
1553 const unsigned char *p
= (const unsigned char *) XSTR (x
, 0);
1556 h
+= (h
<< 7) + *p
++; /* ??? revisit */
1558 hash
+= ((unsigned int) SYMBOL_REF
<< 7) + h
;
1563 if (MEM_VOLATILE_P (x
))
1565 *do_not_record_p
= 1;
1569 hash
+= (unsigned int) MEM
;
1570 /* We used alias set for hashing, but this is not good, since the alias
1571 set may differ in -fprofile-arcs and -fbranch-probabilities compilation
1572 causing the profiles to fail to match. */
1583 case UNSPEC_VOLATILE
:
1584 *do_not_record_p
= 1;
1588 if (MEM_VOLATILE_P (x
))
1590 *do_not_record_p
= 1;
1595 /* We don't want to take the filename and line into account. */
1596 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
)
1597 + hash_string_1 (ASM_OPERANDS_TEMPLATE (x
))
1598 + hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
))
1599 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x
);
1601 if (ASM_OPERANDS_INPUT_LENGTH (x
))
1603 for (i
= 1; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
1605 hash
+= (hash_expr_1 (ASM_OPERANDS_INPUT (x
, i
),
1606 GET_MODE (ASM_OPERANDS_INPUT (x
, i
)),
1608 + hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT
1612 hash
+= hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x
, 0));
1613 x
= ASM_OPERANDS_INPUT (x
, 0);
1614 mode
= GET_MODE (x
);
1624 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
);
1625 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1629 /* If we are about to do the last recursive call
1630 needed at this level, change it into iteration.
1631 This function is called enough to be worth it. */
1638 hash
+= hash_expr_1 (XEXP (x
, i
), 0, do_not_record_p
);
1639 if (*do_not_record_p
)
1643 else if (fmt
[i
] == 'E')
1644 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1646 hash
+= hash_expr_1 (XVECEXP (x
, i
, j
), 0, do_not_record_p
);
1647 if (*do_not_record_p
)
1651 else if (fmt
[i
] == 's')
1652 hash
+= hash_string_1 (XSTR (x
, i
));
1653 else if (fmt
[i
] == 'i')
1654 hash
+= (unsigned int) XINT (x
, i
);
1662 /* Hash a set of register REGNO.
1664 Sets are hashed on the register that is set. This simplifies the PRE copy
1667 ??? May need to make things more elaborate. Later, as necessary. */
1670 hash_set (int regno
, int hash_table_size
)
1675 return hash
% hash_table_size
;
1678 /* Return nonzero if exp1 is equivalent to exp2.
1679 ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
1682 expr_equiv_p (rtx x
, rtx y
)
1691 if (x
== 0 || y
== 0)
1694 code
= GET_CODE (x
);
1695 if (code
!= GET_CODE (y
))
1698 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
1699 if (GET_MODE (x
) != GET_MODE (y
))
1710 return XEXP (x
, 0) == XEXP (y
, 0);
1713 return XSTR (x
, 0) == XSTR (y
, 0);
1716 return REGNO (x
) == REGNO (y
);
1719 /* Can't merge two expressions in different alias sets, since we can
1720 decide that the expression is transparent in a block when it isn't,
1721 due to it being set with the different alias set. */
1722 if (MEM_ALIAS_SET (x
) != MEM_ALIAS_SET (y
))
1725 /* A volatile mem should not be considered equivalent to any other. */
1726 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
1730 /* For commutative operations, check both orders. */
1738 return ((expr_equiv_p (XEXP (x
, 0), XEXP (y
, 0))
1739 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 1)))
1740 || (expr_equiv_p (XEXP (x
, 0), XEXP (y
, 1))
1741 && expr_equiv_p (XEXP (x
, 1), XEXP (y
, 0))));
1744 /* We don't use the generic code below because we want to
1745 disregard filename and line numbers. */
1747 /* A volatile asm isn't equivalent to any other. */
1748 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
1751 if (GET_MODE (x
) != GET_MODE (y
)
1752 || strcmp (ASM_OPERANDS_TEMPLATE (x
), ASM_OPERANDS_TEMPLATE (y
))
1753 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
),
1754 ASM_OPERANDS_OUTPUT_CONSTRAINT (y
))
1755 || ASM_OPERANDS_OUTPUT_IDX (x
) != ASM_OPERANDS_OUTPUT_IDX (y
)
1756 || ASM_OPERANDS_INPUT_LENGTH (x
) != ASM_OPERANDS_INPUT_LENGTH (y
))
1759 if (ASM_OPERANDS_INPUT_LENGTH (x
))
1761 for (i
= ASM_OPERANDS_INPUT_LENGTH (x
) - 1; i
>= 0; i
--)
1762 if (! expr_equiv_p (ASM_OPERANDS_INPUT (x
, i
),
1763 ASM_OPERANDS_INPUT (y
, i
))
1764 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x
, i
),
1765 ASM_OPERANDS_INPUT_CONSTRAINT (y
, i
)))
1775 /* Compare the elements. If any pair of corresponding elements
1776 fail to match, return 0 for the whole thing. */
1778 fmt
= GET_RTX_FORMAT (code
);
1779 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1784 if (! expr_equiv_p (XEXP (x
, i
), XEXP (y
, i
)))
1789 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
1791 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1792 if (! expr_equiv_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
)))
1797 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
1802 if (XINT (x
, i
) != XINT (y
, i
))
1807 if (XWINT (x
, i
) != XWINT (y
, i
))
1822 /* Insert expression X in INSN in the hash TABLE.
1823 If it is already present, record it as the last occurrence in INSN's
1826 MODE is the mode of the value X is being stored into.
1827 It is only used if X is a CONST_INT.
1829 ANTIC_P is nonzero if X is an anticipatable expression.
1830 AVAIL_P is nonzero if X is an available expression. */
1833 insert_expr_in_table (rtx x
, enum machine_mode mode
, rtx insn
, int antic_p
,
1834 int avail_p
, struct hash_table
*table
)
1836 int found
, do_not_record_p
;
1838 struct expr
*cur_expr
, *last_expr
= NULL
;
1839 struct occr
*antic_occr
, *avail_occr
;
1840 struct occr
*last_occr
= NULL
;
1842 hash
= hash_expr (x
, mode
, &do_not_record_p
, table
->size
);
1844 /* Do not insert expression in table if it contains volatile operands,
1845 or if hash_expr determines the expression is something we don't want
1846 to or can't handle. */
1847 if (do_not_record_p
)
1850 cur_expr
= table
->table
[hash
];
1853 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1855 /* If the expression isn't found, save a pointer to the end of
1857 last_expr
= cur_expr
;
1858 cur_expr
= cur_expr
->next_same_hash
;
1863 cur_expr
= gcse_alloc (sizeof (struct expr
));
1864 bytes_used
+= sizeof (struct expr
);
1865 if (table
->table
[hash
] == NULL
)
1866 /* This is the first pattern that hashed to this index. */
1867 table
->table
[hash
] = cur_expr
;
1869 /* Add EXPR to end of this hash chain. */
1870 last_expr
->next_same_hash
= cur_expr
;
1872 /* Set the fields of the expr element. */
1874 cur_expr
->bitmap_index
= table
->n_elems
++;
1875 cur_expr
->next_same_hash
= NULL
;
1876 cur_expr
->antic_occr
= NULL
;
1877 cur_expr
->avail_occr
= NULL
;
1880 /* Now record the occurrence(s). */
1883 antic_occr
= cur_expr
->antic_occr
;
1885 /* Search for another occurrence in the same basic block. */
1886 while (antic_occr
&& BLOCK_NUM (antic_occr
->insn
) != BLOCK_NUM (insn
))
1888 /* If an occurrence isn't found, save a pointer to the end of
1890 last_occr
= antic_occr
;
1891 antic_occr
= antic_occr
->next
;
1895 /* Found another instance of the expression in the same basic block.
1896 Prefer the currently recorded one. We want the first one in the
1897 block and the block is scanned from start to end. */
1898 ; /* nothing to do */
1901 /* First occurrence of this expression in this basic block. */
1902 antic_occr
= gcse_alloc (sizeof (struct occr
));
1903 bytes_used
+= sizeof (struct occr
);
1904 /* First occurrence of this expression in any block? */
1905 if (cur_expr
->antic_occr
== NULL
)
1906 cur_expr
->antic_occr
= antic_occr
;
1908 last_occr
->next
= antic_occr
;
1910 antic_occr
->insn
= insn
;
1911 antic_occr
->next
= NULL
;
1912 antic_occr
->deleted_p
= 0;
1918 avail_occr
= cur_expr
->avail_occr
;
1920 /* Search for another occurrence in the same basic block. */
1921 while (avail_occr
&& BLOCK_NUM (avail_occr
->insn
) != BLOCK_NUM (insn
))
1923 /* If an occurrence isn't found, save a pointer to the end of
1925 last_occr
= avail_occr
;
1926 avail_occr
= avail_occr
->next
;
1930 /* Found another instance of the expression in the same basic block.
1931 Prefer this occurrence to the currently recorded one. We want
1932 the last one in the block and the block is scanned from start
1934 avail_occr
->insn
= insn
;
1937 /* First occurrence of this expression in this basic block. */
1938 avail_occr
= gcse_alloc (sizeof (struct occr
));
1939 bytes_used
+= sizeof (struct occr
);
1941 /* First occurrence of this expression in any block? */
1942 if (cur_expr
->avail_occr
== NULL
)
1943 cur_expr
->avail_occr
= avail_occr
;
1945 last_occr
->next
= avail_occr
;
1947 avail_occr
->insn
= insn
;
1948 avail_occr
->next
= NULL
;
1949 avail_occr
->deleted_p
= 0;
1954 /* Insert pattern X in INSN in the hash table.
1955 X is a SET of a reg to either another reg or a constant.
1956 If it is already present, record it as the last occurrence in INSN's
1960 insert_set_in_table (rtx x
, rtx insn
, struct hash_table
*table
)
1964 struct expr
*cur_expr
, *last_expr
= NULL
;
1965 struct occr
*cur_occr
, *last_occr
= NULL
;
1967 if (GET_CODE (x
) != SET
1968 || ! REG_P (SET_DEST (x
)))
1971 hash
= hash_set (REGNO (SET_DEST (x
)), table
->size
);
1973 cur_expr
= table
->table
[hash
];
1976 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1978 /* If the expression isn't found, save a pointer to the end of
1980 last_expr
= cur_expr
;
1981 cur_expr
= cur_expr
->next_same_hash
;
1986 cur_expr
= gcse_alloc (sizeof (struct expr
));
1987 bytes_used
+= sizeof (struct expr
);
1988 if (table
->table
[hash
] == NULL
)
1989 /* This is the first pattern that hashed to this index. */
1990 table
->table
[hash
] = cur_expr
;
1992 /* Add EXPR to end of this hash chain. */
1993 last_expr
->next_same_hash
= cur_expr
;
1995 /* Set the fields of the expr element.
1996 We must copy X because it can be modified when copy propagation is
1997 performed on its operands. */
1998 cur_expr
->expr
= copy_rtx (x
);
1999 cur_expr
->bitmap_index
= table
->n_elems
++;
2000 cur_expr
->next_same_hash
= NULL
;
2001 cur_expr
->antic_occr
= NULL
;
2002 cur_expr
->avail_occr
= NULL
;
2005 /* Now record the occurrence. */
2006 cur_occr
= cur_expr
->avail_occr
;
2008 /* Search for another occurrence in the same basic block. */
2009 while (cur_occr
&& BLOCK_NUM (cur_occr
->insn
) != BLOCK_NUM (insn
))
2011 /* If an occurrence isn't found, save a pointer to the end of
2013 last_occr
= cur_occr
;
2014 cur_occr
= cur_occr
->next
;
2018 /* Found another instance of the expression in the same basic block.
2019 Prefer this occurrence to the currently recorded one. We want the
2020 last one in the block and the block is scanned from start to end. */
2021 cur_occr
->insn
= insn
;
2024 /* First occurrence of this expression in this basic block. */
2025 cur_occr
= gcse_alloc (sizeof (struct occr
));
2026 bytes_used
+= sizeof (struct occr
);
2028 /* First occurrence of this expression in any block? */
2029 if (cur_expr
->avail_occr
== NULL
)
2030 cur_expr
->avail_occr
= cur_occr
;
2032 last_occr
->next
= cur_occr
;
2034 cur_occr
->insn
= insn
;
2035 cur_occr
->next
= NULL
;
2036 cur_occr
->deleted_p
= 0;
2040 /* Determine whether the rtx X should be treated as a constant for
2041 the purposes of GCSE's constant propagation. */
2044 gcse_constant_p (rtx x
)
2046 /* Consider a COMPARE of two integers constant. */
2047 if (GET_CODE (x
) == COMPARE
2048 && GET_CODE (XEXP (x
, 0)) == CONST_INT
2049 && GET_CODE (XEXP (x
, 1)) == CONST_INT
)
2052 /* Consider a COMPARE of the same registers is a constant
2053 if they are not floating point registers. */
2054 if (GET_CODE(x
) == COMPARE
2055 && REG_P (XEXP (x
, 0)) && REG_P (XEXP (x
, 1))
2056 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (x
, 1))
2057 && ! FLOAT_MODE_P (GET_MODE (XEXP (x
, 0)))
2058 && ! FLOAT_MODE_P (GET_MODE (XEXP (x
, 1))))
2061 return CONSTANT_P (x
);
2064 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
2068 hash_scan_set (rtx pat
, rtx insn
, struct hash_table
*table
)
2070 rtx src
= SET_SRC (pat
);
2071 rtx dest
= SET_DEST (pat
);
2074 if (GET_CODE (src
) == CALL
)
2075 hash_scan_call (src
, insn
, table
);
2077 else if (REG_P (dest
))
2079 unsigned int regno
= REGNO (dest
);
2082 /* If this is a single set and we are doing constant propagation,
2083 see if a REG_NOTE shows this equivalent to a constant. */
2084 if (table
->set_p
&& (note
= find_reg_equal_equiv_note (insn
)) != 0
2085 && gcse_constant_p (XEXP (note
, 0)))
2086 src
= XEXP (note
, 0), pat
= gen_rtx_SET (VOIDmode
, dest
, src
);
2088 /* Only record sets of pseudo-regs in the hash table. */
2090 && regno
>= FIRST_PSEUDO_REGISTER
2091 /* Don't GCSE something if we can't do a reg/reg copy. */
2092 && can_copy_p (GET_MODE (dest
))
2093 /* GCSE commonly inserts instruction after the insn. We can't
2094 do that easily for EH_REGION notes so disable GCSE on these
2096 && !find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
2097 /* Is SET_SRC something we want to gcse? */
2098 && want_to_gcse_p (src
)
2099 /* Don't CSE a nop. */
2100 && ! set_noop_p (pat
)
2101 /* Don't GCSE if it has attached REG_EQUIV note.
2102 At this point this only function parameters should have
2103 REG_EQUIV notes and if the argument slot is used somewhere
2104 explicitly, it means address of parameter has been taken,
2105 so we should not extend the lifetime of the pseudo. */
2106 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
2107 || ! MEM_P (XEXP (note
, 0))))
2109 /* An expression is not anticipatable if its operands are
2110 modified before this insn or if this is not the only SET in
2112 int antic_p
= oprs_anticipatable_p (src
, insn
) && single_set (insn
);
2113 /* An expression is not available if its operands are
2114 subsequently modified, including this insn. It's also not
2115 available if this is a branch, because we can't insert
2116 a set after the branch. */
2117 int avail_p
= (oprs_available_p (src
, insn
)
2118 && ! JUMP_P (insn
));
2120 insert_expr_in_table (src
, GET_MODE (dest
), insn
, antic_p
, avail_p
, table
);
2123 /* Record sets for constant/copy propagation. */
2124 else if (table
->set_p
2125 && regno
>= FIRST_PSEUDO_REGISTER
2127 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
2128 && can_copy_p (GET_MODE (dest
))
2129 && REGNO (src
) != regno
)
2130 || gcse_constant_p (src
))
2131 /* A copy is not available if its src or dest is subsequently
2132 modified. Here we want to search from INSN+1 on, but
2133 oprs_available_p searches from INSN on. */
2134 && (insn
== BB_END (BLOCK_FOR_INSN (insn
))
2135 || ((tmp
= next_nonnote_insn (insn
)) != NULL_RTX
2136 && oprs_available_p (pat
, tmp
))))
2137 insert_set_in_table (pat
, insn
, table
);
2139 /* In case of store we want to consider the memory value as available in
2140 the REG stored in that memory. This makes it possible to remove
2141 redundant loads from due to stores to the same location. */
2142 else if (flag_gcse_las
&& REG_P (src
) && MEM_P (dest
))
2144 unsigned int regno
= REGNO (src
);
2146 /* Do not do this for constant/copy propagation. */
2148 /* Only record sets of pseudo-regs in the hash table. */
2149 && regno
>= FIRST_PSEUDO_REGISTER
2150 /* Don't GCSE something if we can't do a reg/reg copy. */
2151 && can_copy_p (GET_MODE (src
))
2152 /* GCSE commonly inserts instruction after the insn. We can't
2153 do that easily for EH_REGION notes so disable GCSE on these
2155 && ! find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
2156 /* Is SET_DEST something we want to gcse? */
2157 && want_to_gcse_p (dest
)
2158 /* Don't CSE a nop. */
2159 && ! set_noop_p (pat
)
2160 /* Don't GCSE if it has attached REG_EQUIV note.
2161 At this point this only function parameters should have
2162 REG_EQUIV notes and if the argument slot is used somewhere
2163 explicitly, it means address of parameter has been taken,
2164 so we should not extend the lifetime of the pseudo. */
2165 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
2166 || ! MEM_P (XEXP (note
, 0))))
2168 /* Stores are never anticipatable. */
2170 /* An expression is not available if its operands are
2171 subsequently modified, including this insn. It's also not
2172 available if this is a branch, because we can't insert
2173 a set after the branch. */
2174 int avail_p
= oprs_available_p (dest
, insn
)
2177 /* Record the memory expression (DEST) in the hash table. */
2178 insert_expr_in_table (dest
, GET_MODE (dest
), insn
,
2179 antic_p
, avail_p
, table
);
2185 hash_scan_clobber (rtx x ATTRIBUTE_UNUSED
, rtx insn ATTRIBUTE_UNUSED
,
2186 struct hash_table
*table ATTRIBUTE_UNUSED
)
2188 /* Currently nothing to do. */
2192 hash_scan_call (rtx x ATTRIBUTE_UNUSED
, rtx insn ATTRIBUTE_UNUSED
,
2193 struct hash_table
*table ATTRIBUTE_UNUSED
)
2195 /* Currently nothing to do. */
2198 /* Process INSN and add hash table entries as appropriate.
2200 Only available expressions that set a single pseudo-reg are recorded.
2202 Single sets in a PARALLEL could be handled, but it's an extra complication
2203 that isn't dealt with right now. The trick is handling the CLOBBERs that
2204 are also in the PARALLEL. Later.
2206 If SET_P is nonzero, this is for the assignment hash table,
2207 otherwise it is for the expression hash table.
2208 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
2209 not record any expressions. */
2212 hash_scan_insn (rtx insn
, struct hash_table
*table
, int in_libcall_block
)
2214 rtx pat
= PATTERN (insn
);
2217 if (in_libcall_block
)
2220 /* Pick out the sets of INSN and for other forms of instructions record
2221 what's been modified. */
2223 if (GET_CODE (pat
) == SET
)
2224 hash_scan_set (pat
, insn
, table
);
2225 else if (GET_CODE (pat
) == PARALLEL
)
2226 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2228 rtx x
= XVECEXP (pat
, 0, i
);
2230 if (GET_CODE (x
) == SET
)
2231 hash_scan_set (x
, insn
, table
);
2232 else if (GET_CODE (x
) == CLOBBER
)
2233 hash_scan_clobber (x
, insn
, table
);
2234 else if (GET_CODE (x
) == CALL
)
2235 hash_scan_call (x
, insn
, table
);
2238 else if (GET_CODE (pat
) == CLOBBER
)
2239 hash_scan_clobber (pat
, insn
, table
);
2240 else if (GET_CODE (pat
) == CALL
)
2241 hash_scan_call (pat
, insn
, table
);
2245 dump_hash_table (FILE *file
, const char *name
, struct hash_table
*table
)
2248 /* Flattened out table, so it's printed in proper order. */
2249 struct expr
**flat_table
;
2250 unsigned int *hash_val
;
2253 flat_table
= xcalloc (table
->n_elems
, sizeof (struct expr
*));
2254 hash_val
= xmalloc (table
->n_elems
* sizeof (unsigned int));
2256 for (i
= 0; i
< (int) table
->size
; i
++)
2257 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
2259 flat_table
[expr
->bitmap_index
] = expr
;
2260 hash_val
[expr
->bitmap_index
] = i
;
2263 fprintf (file
, "%s hash table (%d buckets, %d entries)\n",
2264 name
, table
->size
, table
->n_elems
);
2266 for (i
= 0; i
< (int) table
->n_elems
; i
++)
2267 if (flat_table
[i
] != 0)
2269 expr
= flat_table
[i
];
2270 fprintf (file
, "Index %d (hash value %d)\n ",
2271 expr
->bitmap_index
, hash_val
[i
]);
2272 print_rtl (file
, expr
->expr
);
2273 fprintf (file
, "\n");
2276 fprintf (file
, "\n");
2282 /* Record register first/last/block set information for REGNO in INSN.
2284 first_set records the first place in the block where the register
2285 is set and is used to compute "anticipatability".
2287 last_set records the last place in the block where the register
2288 is set and is used to compute "availability".
2290 last_bb records the block for which first_set and last_set are
2291 valid, as a quick test to invalidate them.
2293 reg_set_in_block records whether the register is set in the block
2294 and is used to compute "transparency". */
2297 record_last_reg_set_info (rtx insn
, int regno
)
2299 struct reg_avail_info
*info
= ®_avail_info
[regno
];
2300 int cuid
= INSN_CUID (insn
);
2302 info
->last_set
= cuid
;
2303 if (info
->last_bb
!= current_bb
)
2305 info
->last_bb
= current_bb
;
2306 info
->first_set
= cuid
;
2307 SET_BIT (reg_set_in_block
[current_bb
->index
], regno
);
2312 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
2313 Note we store a pair of elements in the list, so they have to be
2314 taken off pairwise. */
2317 canon_list_insert (rtx dest ATTRIBUTE_UNUSED
, rtx unused1 ATTRIBUTE_UNUSED
,
2320 rtx dest_addr
, insn
;
2323 while (GET_CODE (dest
) == SUBREG
2324 || GET_CODE (dest
) == ZERO_EXTRACT
2325 || GET_CODE (dest
) == SIGN_EXTRACT
2326 || GET_CODE (dest
) == STRICT_LOW_PART
)
2327 dest
= XEXP (dest
, 0);
2329 /* If DEST is not a MEM, then it will not conflict with a load. Note
2330 that function calls are assumed to clobber memory, but are handled
2336 dest_addr
= get_addr (XEXP (dest
, 0));
2337 dest_addr
= canon_rtx (dest_addr
);
2338 insn
= (rtx
) v_insn
;
2339 bb
= BLOCK_NUM (insn
);
2341 canon_modify_mem_list
[bb
] =
2342 alloc_EXPR_LIST (VOIDmode
, dest_addr
, canon_modify_mem_list
[bb
]);
2343 canon_modify_mem_list
[bb
] =
2344 alloc_EXPR_LIST (VOIDmode
, dest
, canon_modify_mem_list
[bb
]);
2345 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2348 /* Record memory modification information for INSN. We do not actually care
2349 about the memory location(s) that are set, or even how they are set (consider
2350 a CALL_INSN). We merely need to record which insns modify memory. */
2353 record_last_mem_set_info (rtx insn
)
2355 int bb
= BLOCK_NUM (insn
);
2357 /* load_killed_in_block_p will handle the case of calls clobbering
2359 modify_mem_list
[bb
] = alloc_INSN_LIST (insn
, modify_mem_list
[bb
]);
2360 bitmap_set_bit (modify_mem_list_set
, bb
);
2364 /* Note that traversals of this loop (other than for free-ing)
2365 will break after encountering a CALL_INSN. So, there's no
2366 need to insert a pair of items, as canon_list_insert does. */
2367 canon_modify_mem_list
[bb
] =
2368 alloc_INSN_LIST (insn
, canon_modify_mem_list
[bb
]);
2369 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2372 note_stores (PATTERN (insn
), canon_list_insert
, (void*) insn
);
2375 /* Called from compute_hash_table via note_stores to handle one
2376 SET or CLOBBER in an insn. DATA is really the instruction in which
2377 the SET is taking place. */
2380 record_last_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
, void *data
)
2382 rtx last_set_insn
= (rtx
) data
;
2384 if (GET_CODE (dest
) == SUBREG
)
2385 dest
= SUBREG_REG (dest
);
2388 record_last_reg_set_info (last_set_insn
, REGNO (dest
));
2389 else if (MEM_P (dest
)
2390 /* Ignore pushes, they clobber nothing. */
2391 && ! push_operand (dest
, GET_MODE (dest
)))
2392 record_last_mem_set_info (last_set_insn
);
2395 /* Top level function to create an expression or assignment hash table.
2397 Expression entries are placed in the hash table if
2398 - they are of the form (set (pseudo-reg) src),
2399 - src is something we want to perform GCSE on,
2400 - none of the operands are subsequently modified in the block
2402 Assignment entries are placed in the hash table if
2403 - they are of the form (set (pseudo-reg) src),
2404 - src is something we want to perform const/copy propagation on,
2405 - none of the operands or target are subsequently modified in the block
2407 Currently src must be a pseudo-reg or a const_int.
2409 TABLE is the table computed. */
2412 compute_hash_table_work (struct hash_table
*table
)
2416 /* While we compute the hash table we also compute a bit array of which
2417 registers are set in which blocks.
2418 ??? This isn't needed during const/copy propagation, but it's cheap to
2420 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
2422 /* re-Cache any INSN_LIST nodes we have allocated. */
2423 clear_modify_mem_tables ();
2424 /* Some working arrays used to track first and last set in each block. */
2425 reg_avail_info
= gmalloc (max_gcse_regno
* sizeof (struct reg_avail_info
));
2427 for (i
= 0; i
< max_gcse_regno
; ++i
)
2428 reg_avail_info
[i
].last_bb
= NULL
;
2430 FOR_EACH_BB (current_bb
)
2434 int in_libcall_block
;
2436 /* First pass over the instructions records information used to
2437 determine when registers and memory are first and last set.
2438 ??? hard-reg reg_set_in_block computation
2439 could be moved to compute_sets since they currently don't change. */
2441 for (insn
= BB_HEAD (current_bb
);
2442 insn
&& insn
!= NEXT_INSN (BB_END (current_bb
));
2443 insn
= NEXT_INSN (insn
))
2445 if (! INSN_P (insn
))
2450 bool clobbers_all
= false;
2451 #ifdef NON_SAVING_SETJMP
2452 if (NON_SAVING_SETJMP
2453 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
2454 clobbers_all
= true;
2457 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2459 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2460 record_last_reg_set_info (insn
, regno
);
2465 note_stores (PATTERN (insn
), record_last_set_info
, insn
);
2468 /* Insert implicit sets in the hash table. */
2470 && implicit_sets
[current_bb
->index
] != NULL_RTX
)
2471 hash_scan_set (implicit_sets
[current_bb
->index
],
2472 BB_HEAD (current_bb
), table
);
2474 /* The next pass builds the hash table. */
2476 for (insn
= BB_HEAD (current_bb
), in_libcall_block
= 0;
2477 insn
&& insn
!= NEXT_INSN (BB_END (current_bb
));
2478 insn
= NEXT_INSN (insn
))
2481 if (find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2482 in_libcall_block
= 1;
2483 else if (table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2484 in_libcall_block
= 0;
2485 hash_scan_insn (insn
, table
, in_libcall_block
);
2486 if (!table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2487 in_libcall_block
= 0;
2491 free (reg_avail_info
);
2492 reg_avail_info
= NULL
;
2495 /* Allocate space for the set/expr hash TABLE.
2496 N_INSNS is the number of instructions in the function.
2497 It is used to determine the number of buckets to use.
2498 SET_P determines whether set or expression table will
2502 alloc_hash_table (int n_insns
, struct hash_table
*table
, int set_p
)
2506 table
->size
= n_insns
/ 4;
2507 if (table
->size
< 11)
2510 /* Attempt to maintain efficient use of hash table.
2511 Making it an odd number is simplest for now.
2512 ??? Later take some measurements. */
2514 n
= table
->size
* sizeof (struct expr
*);
2515 table
->table
= gmalloc (n
);
2516 table
->set_p
= set_p
;
2519 /* Free things allocated by alloc_hash_table. */
2522 free_hash_table (struct hash_table
*table
)
2524 free (table
->table
);
2527 /* Compute the hash TABLE for doing copy/const propagation or
2528 expression hash table. */
2531 compute_hash_table (struct hash_table
*table
)
2533 /* Initialize count of number of entries in hash table. */
2535 memset (table
->table
, 0, table
->size
* sizeof (struct expr
*));
2537 compute_hash_table_work (table
);
2540 /* Expression tracking support. */
2542 /* Lookup pattern PAT in the expression TABLE.
2543 The result is a pointer to the table entry, or NULL if not found. */
2545 static struct expr
*
2546 lookup_expr (rtx pat
, struct hash_table
*table
)
2548 int do_not_record_p
;
2549 unsigned int hash
= hash_expr (pat
, GET_MODE (pat
), &do_not_record_p
,
2553 if (do_not_record_p
)
2556 expr
= table
->table
[hash
];
2558 while (expr
&& ! expr_equiv_p (expr
->expr
, pat
))
2559 expr
= expr
->next_same_hash
;
2564 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2565 table entry, or NULL if not found. */
2567 static struct expr
*
2568 lookup_set (unsigned int regno
, struct hash_table
*table
)
2570 unsigned int hash
= hash_set (regno
, table
->size
);
2573 expr
= table
->table
[hash
];
2575 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
)
2576 expr
= expr
->next_same_hash
;
2581 /* Return the next entry for REGNO in list EXPR. */
2583 static struct expr
*
2584 next_set (unsigned int regno
, struct expr
*expr
)
2587 expr
= expr
->next_same_hash
;
2588 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
);
2593 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2594 types may be mixed. */
2597 free_insn_expr_list_list (rtx
*listp
)
2601 for (list
= *listp
; list
; list
= next
)
2603 next
= XEXP (list
, 1);
2604 if (GET_CODE (list
) == EXPR_LIST
)
2605 free_EXPR_LIST_node (list
);
2607 free_INSN_LIST_node (list
);
2613 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2615 clear_modify_mem_tables (void)
2619 EXECUTE_IF_SET_IN_BITMAP
2620 (modify_mem_list_set
, 0, i
, free_INSN_LIST_list (modify_mem_list
+ i
));
2621 bitmap_clear (modify_mem_list_set
);
2623 EXECUTE_IF_SET_IN_BITMAP
2624 (canon_modify_mem_list_set
, 0, i
,
2625 free_insn_expr_list_list (canon_modify_mem_list
+ i
));
2626 bitmap_clear (canon_modify_mem_list_set
);
2629 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2632 free_modify_mem_tables (void)
2634 clear_modify_mem_tables ();
2635 free (modify_mem_list
);
2636 free (canon_modify_mem_list
);
2637 modify_mem_list
= 0;
2638 canon_modify_mem_list
= 0;
2641 /* Reset tables used to keep track of what's still available [since the
2642 start of the block]. */
2645 reset_opr_set_tables (void)
2647 /* Maintain a bitmap of which regs have been set since beginning of
2649 CLEAR_REG_SET (reg_set_bitmap
);
2651 /* Also keep a record of the last instruction to modify memory.
2652 For now this is very trivial, we only record whether any memory
2653 location has been modified. */
2654 clear_modify_mem_tables ();
2657 /* Return nonzero if the operands of X are not set before INSN in
2658 INSN's basic block. */
2661 oprs_not_set_p (rtx x
, rtx insn
)
2670 code
= GET_CODE (x
);
2686 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn
),
2687 INSN_CUID (insn
), x
, 0))
2690 return oprs_not_set_p (XEXP (x
, 0), insn
);
2693 return ! REGNO_REG_SET_P (reg_set_bitmap
, REGNO (x
));
2699 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2703 /* If we are about to do the last recursive call
2704 needed at this level, change it into iteration.
2705 This function is called enough to be worth it. */
2707 return oprs_not_set_p (XEXP (x
, i
), insn
);
2709 if (! oprs_not_set_p (XEXP (x
, i
), insn
))
2712 else if (fmt
[i
] == 'E')
2713 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2714 if (! oprs_not_set_p (XVECEXP (x
, i
, j
), insn
))
2721 /* Mark things set by a CALL. */
2724 mark_call (rtx insn
)
2726 if (! CONST_OR_PURE_CALL_P (insn
))
2727 record_last_mem_set_info (insn
);
2730 /* Mark things set by a SET. */
2733 mark_set (rtx pat
, rtx insn
)
2735 rtx dest
= SET_DEST (pat
);
2737 while (GET_CODE (dest
) == SUBREG
2738 || GET_CODE (dest
) == ZERO_EXTRACT
2739 || GET_CODE (dest
) == SIGN_EXTRACT
2740 || GET_CODE (dest
) == STRICT_LOW_PART
)
2741 dest
= XEXP (dest
, 0);
2744 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (dest
));
2745 else if (MEM_P (dest
))
2746 record_last_mem_set_info (insn
);
2748 if (GET_CODE (SET_SRC (pat
)) == CALL
)
2752 /* Record things set by a CLOBBER. */
2755 mark_clobber (rtx pat
, rtx insn
)
2757 rtx clob
= XEXP (pat
, 0);
2759 while (GET_CODE (clob
) == SUBREG
|| GET_CODE (clob
) == STRICT_LOW_PART
)
2760 clob
= XEXP (clob
, 0);
2763 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (clob
));
2765 record_last_mem_set_info (insn
);
2768 /* Record things set by INSN.
2769 This data is used by oprs_not_set_p. */
2772 mark_oprs_set (rtx insn
)
2774 rtx pat
= PATTERN (insn
);
2777 if (GET_CODE (pat
) == SET
)
2778 mark_set (pat
, insn
);
2779 else if (GET_CODE (pat
) == PARALLEL
)
2780 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2782 rtx x
= XVECEXP (pat
, 0, i
);
2784 if (GET_CODE (x
) == SET
)
2786 else if (GET_CODE (x
) == CLOBBER
)
2787 mark_clobber (x
, insn
);
2788 else if (GET_CODE (x
) == CALL
)
2792 else if (GET_CODE (pat
) == CLOBBER
)
2793 mark_clobber (pat
, insn
);
2794 else if (GET_CODE (pat
) == CALL
)
2799 /* Compute copy/constant propagation working variables. */
2801 /* Local properties of assignments. */
2802 static sbitmap
*cprop_pavloc
;
2803 static sbitmap
*cprop_absaltered
;
2805 /* Global properties of assignments (computed from the local properties). */
2806 static sbitmap
*cprop_avin
;
2807 static sbitmap
*cprop_avout
;
2809 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
2810 basic blocks. N_SETS is the number of sets. */
2813 alloc_cprop_mem (int n_blocks
, int n_sets
)
2815 cprop_pavloc
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2816 cprop_absaltered
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2818 cprop_avin
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2819 cprop_avout
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2822 /* Free vars used by copy/const propagation. */
2825 free_cprop_mem (void)
2827 sbitmap_vector_free (cprop_pavloc
);
2828 sbitmap_vector_free (cprop_absaltered
);
2829 sbitmap_vector_free (cprop_avin
);
2830 sbitmap_vector_free (cprop_avout
);
2833 /* For each block, compute whether X is transparent. X is either an
2834 expression or an assignment [though we don't care which, for this context
2835 an assignment is treated as an expression]. For each block where an
2836 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
2840 compute_transp (rtx x
, int indx
, sbitmap
*bmap
, int set_p
)
2848 /* repeat is used to turn tail-recursion into iteration since GCC
2849 can't do it when there's no return value. */
2855 code
= GET_CODE (x
);
2861 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
2864 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
2865 SET_BIT (bmap
[bb
->index
], indx
);
2869 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
2870 SET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
2875 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
2878 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
2879 RESET_BIT (bmap
[bb
->index
], indx
);
2883 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
2884 RESET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
2893 rtx list_entry
= canon_modify_mem_list
[bb
->index
];
2897 rtx dest
, dest_addr
;
2899 if (CALL_P (XEXP (list_entry
, 0)))
2902 SET_BIT (bmap
[bb
->index
], indx
);
2904 RESET_BIT (bmap
[bb
->index
], indx
);
2907 /* LIST_ENTRY must be an INSN of some kind that sets memory.
2908 Examine each hunk of memory that is modified. */
2910 dest
= XEXP (list_entry
, 0);
2911 list_entry
= XEXP (list_entry
, 1);
2912 dest_addr
= XEXP (list_entry
, 0);
2914 if (canon_true_dependence (dest
, GET_MODE (dest
), dest_addr
,
2915 x
, rtx_addr_varies_p
))
2918 SET_BIT (bmap
[bb
->index
], indx
);
2920 RESET_BIT (bmap
[bb
->index
], indx
);
2923 list_entry
= XEXP (list_entry
, 1);
2946 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2950 /* If we are about to do the last recursive call
2951 needed at this level, change it into iteration.
2952 This function is called enough to be worth it. */
2959 compute_transp (XEXP (x
, i
), indx
, bmap
, set_p
);
2961 else if (fmt
[i
] == 'E')
2962 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2963 compute_transp (XVECEXP (x
, i
, j
), indx
, bmap
, set_p
);
2967 /* Top level routine to do the dataflow analysis needed by copy/const
2971 compute_cprop_data (void)
2973 compute_local_properties (cprop_absaltered
, cprop_pavloc
, NULL
, &set_hash_table
);
2974 compute_available (cprop_pavloc
, cprop_absaltered
,
2975 cprop_avout
, cprop_avin
);
2978 /* Copy/constant propagation. */
2980 /* Maximum number of register uses in an insn that we handle. */
2983 /* Table of uses found in an insn.
2984 Allocated statically to avoid alloc/free complexity and overhead. */
2985 static struct reg_use reg_use_table
[MAX_USES
];
2987 /* Index into `reg_use_table' while building it. */
2988 static int reg_use_count
;
2990 /* Set up a list of register numbers used in INSN. The found uses are stored
2991 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
2992 and contains the number of uses in the table upon exit.
2994 ??? If a register appears multiple times we will record it multiple times.
2995 This doesn't hurt anything but it will slow things down. */
2998 find_used_regs (rtx
*xptr
, void *data ATTRIBUTE_UNUSED
)
3005 /* repeat is used to turn tail-recursion into iteration since GCC
3006 can't do it when there's no return value. */
3011 code
= GET_CODE (x
);
3014 if (reg_use_count
== MAX_USES
)
3017 reg_use_table
[reg_use_count
].reg_rtx
= x
;
3021 /* Recursively scan the operands of this expression. */
3023 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
3027 /* If we are about to do the last recursive call
3028 needed at this level, change it into iteration.
3029 This function is called enough to be worth it. */
3036 find_used_regs (&XEXP (x
, i
), data
);
3038 else if (fmt
[i
] == 'E')
3039 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
3040 find_used_regs (&XVECEXP (x
, i
, j
), data
);
3044 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
3045 Returns nonzero is successful. */
3048 try_replace_reg (rtx from
, rtx to
, rtx insn
)
3050 rtx note
= find_reg_equal_equiv_note (insn
);
3053 rtx set
= single_set (insn
);
3055 validate_replace_src_group (from
, to
, insn
);
3056 if (num_changes_pending () && apply_change_group ())
3059 /* Try to simplify SET_SRC if we have substituted a constant. */
3060 if (success
&& set
&& CONSTANT_P (to
))
3062 src
= simplify_rtx (SET_SRC (set
));
3065 validate_change (insn
, &SET_SRC (set
), src
, 0);
3068 /* If there is already a NOTE, update the expression in it with our
3071 XEXP (note
, 0) = simplify_replace_rtx (XEXP (note
, 0), from
, to
);
3073 if (!success
&& set
&& reg_mentioned_p (from
, SET_SRC (set
)))
3075 /* If above failed and this is a single set, try to simplify the source of
3076 the set given our substitution. We could perhaps try this for multiple
3077 SETs, but it probably won't buy us anything. */
3078 src
= simplify_replace_rtx (SET_SRC (set
), from
, to
);
3080 if (!rtx_equal_p (src
, SET_SRC (set
))
3081 && validate_change (insn
, &SET_SRC (set
), src
, 0))
3084 /* If we've failed to do replacement, have a single SET, don't already
3085 have a note, and have no special SET, add a REG_EQUAL note to not
3086 lose information. */
3087 if (!success
&& note
== 0 && set
!= 0
3088 && GET_CODE (XEXP (set
, 0)) != ZERO_EXTRACT
3089 && GET_CODE (XEXP (set
, 0)) != SIGN_EXTRACT
)
3090 note
= set_unique_reg_note (insn
, REG_EQUAL
, copy_rtx (src
));
3093 /* REG_EQUAL may get simplified into register.
3094 We don't allow that. Remove that note. This code ought
3095 not to happen, because previous code ought to synthesize
3096 reg-reg move, but be on the safe side. */
3097 if (note
&& REG_P (XEXP (note
, 0)))
3098 remove_note (insn
, note
);
3103 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
3104 NULL no such set is found. */
3106 static struct expr
*
3107 find_avail_set (int regno
, rtx insn
)
3109 /* SET1 contains the last set found that can be returned to the caller for
3110 use in a substitution. */
3111 struct expr
*set1
= 0;
3113 /* Loops are not possible here. To get a loop we would need two sets
3114 available at the start of the block containing INSN. ie we would
3115 need two sets like this available at the start of the block:
3117 (set (reg X) (reg Y))
3118 (set (reg Y) (reg X))
3120 This can not happen since the set of (reg Y) would have killed the
3121 set of (reg X) making it unavailable at the start of this block. */
3125 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
3127 /* Find a set that is available at the start of the block
3128 which contains INSN. */
3131 if (TEST_BIT (cprop_avin
[BLOCK_NUM (insn
)], set
->bitmap_index
))
3133 set
= next_set (regno
, set
);
3136 /* If no available set was found we've reached the end of the
3137 (possibly empty) copy chain. */
3141 if (GET_CODE (set
->expr
) != SET
)
3144 src
= SET_SRC (set
->expr
);
3146 /* We know the set is available.
3147 Now check that SRC is ANTLOC (i.e. none of the source operands
3148 have changed since the start of the block).
3150 If the source operand changed, we may still use it for the next
3151 iteration of this loop, but we may not use it for substitutions. */
3153 if (gcse_constant_p (src
) || oprs_not_set_p (src
, insn
))
3156 /* If the source of the set is anything except a register, then
3157 we have reached the end of the copy chain. */
3161 /* Follow the copy chain, ie start another iteration of the loop
3162 and see if we have an available copy into SRC. */
3163 regno
= REGNO (src
);
3166 /* SET1 holds the last set that was available and anticipatable at
3171 /* Subroutine of cprop_insn that tries to propagate constants into
3172 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
3173 it is the instruction that immediately precedes JUMP, and must be a
3174 single SET of a register. FROM is what we will try to replace,
3175 SRC is the constant we will try to substitute for it. Returns nonzero
3176 if a change was made. */
3179 cprop_jump (basic_block bb
, rtx setcc
, rtx jump
, rtx from
, rtx src
)
3181 rtx
new, set_src
, note_src
;
3182 rtx set
= pc_set (jump
);
3183 rtx note
= find_reg_equal_equiv_note (jump
);
3187 note_src
= XEXP (note
, 0);
3188 if (GET_CODE (note_src
) == EXPR_LIST
)
3189 note_src
= NULL_RTX
;
3191 else note_src
= NULL_RTX
;
3193 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
3194 set_src
= note_src
? note_src
: SET_SRC (set
);
3196 /* First substitute the SETCC condition into the JUMP instruction,
3197 then substitute that given values into this expanded JUMP. */
3198 if (setcc
!= NULL_RTX
3199 && !modified_between_p (from
, setcc
, jump
)
3200 && !modified_between_p (src
, setcc
, jump
))
3203 rtx setcc_set
= single_set (setcc
);
3204 rtx setcc_note
= find_reg_equal_equiv_note (setcc
);
3205 setcc_src
= (setcc_note
&& GET_CODE (XEXP (setcc_note
, 0)) != EXPR_LIST
)
3206 ? XEXP (setcc_note
, 0) : SET_SRC (setcc_set
);
3207 set_src
= simplify_replace_rtx (set_src
, SET_DEST (setcc_set
),
3213 new = simplify_replace_rtx (set_src
, from
, src
);
3215 /* If no simplification can be made, then try the next register. */
3216 if (rtx_equal_p (new, SET_SRC (set
)))
3219 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
3224 /* Ensure the value computed inside the jump insn to be equivalent
3225 to one computed by setcc. */
3226 if (setcc
&& modified_in_p (new, setcc
))
3228 if (! validate_change (jump
, &SET_SRC (set
), new, 0))
3230 /* When (some) constants are not valid in a comparison, and there
3231 are two registers to be replaced by constants before the entire
3232 comparison can be folded into a constant, we need to keep
3233 intermediate information in REG_EQUAL notes. For targets with
3234 separate compare insns, such notes are added by try_replace_reg.
3235 When we have a combined compare-and-branch instruction, however,
3236 we need to attach a note to the branch itself to make this
3237 optimization work. */
3239 if (!rtx_equal_p (new, note_src
))
3240 set_unique_reg_note (jump
, REG_EQUAL
, copy_rtx (new));
3244 /* Remove REG_EQUAL note after simplification. */
3246 remove_note (jump
, note
);
3248 /* If this has turned into an unconditional jump,
3249 then put a barrier after it so that the unreachable
3250 code will be deleted. */
3251 if (GET_CODE (SET_SRC (set
)) == LABEL_REF
)
3252 emit_barrier_after (jump
);
3256 /* Delete the cc0 setter. */
3257 if (setcc
!= NULL
&& CC0_P (SET_DEST (single_set (setcc
))))
3258 delete_insn (setcc
);
3261 run_jump_opt_after_gcse
= 1;
3264 if (gcse_file
!= NULL
)
3267 "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
3268 REGNO (from
), INSN_UID (jump
));
3269 print_rtl (gcse_file
, src
);
3270 fprintf (gcse_file
, "\n");
3272 purge_dead_edges (bb
);
3278 constprop_register (rtx insn
, rtx from
, rtx to
, int alter_jumps
)
3282 /* Check for reg or cc0 setting instructions followed by
3283 conditional branch instructions first. */
3285 && (sset
= single_set (insn
)) != NULL
3287 && any_condjump_p (NEXT_INSN (insn
)) && onlyjump_p (NEXT_INSN (insn
)))
3289 rtx dest
= SET_DEST (sset
);
3290 if ((REG_P (dest
) || CC0_P (dest
))
3291 && cprop_jump (BLOCK_FOR_INSN (insn
), insn
, NEXT_INSN (insn
), from
, to
))
3295 /* Handle normal insns next. */
3296 if (NONJUMP_INSN_P (insn
)
3297 && try_replace_reg (from
, to
, insn
))
3300 /* Try to propagate a CONST_INT into a conditional jump.
3301 We're pretty specific about what we will handle in this
3302 code, we can extend this as necessary over time.
3304 Right now the insn in question must look like
3305 (set (pc) (if_then_else ...)) */
3306 else if (alter_jumps
&& any_condjump_p (insn
) && onlyjump_p (insn
))
3307 return cprop_jump (BLOCK_FOR_INSN (insn
), NULL
, insn
, from
, to
);
3311 /* Perform constant and copy propagation on INSN.
3312 The result is nonzero if a change was made. */
3315 cprop_insn (rtx insn
, int alter_jumps
)
3317 struct reg_use
*reg_used
;
3325 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
3327 note
= find_reg_equal_equiv_note (insn
);
3329 /* We may win even when propagating constants into notes. */
3331 find_used_regs (&XEXP (note
, 0), NULL
);
3333 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
3334 reg_used
++, reg_use_count
--)
3336 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
3340 /* Ignore registers created by GCSE.
3341 We do this because ... */
3342 if (regno
>= max_gcse_regno
)
3345 /* If the register has already been set in this block, there's
3346 nothing we can do. */
3347 if (! oprs_not_set_p (reg_used
->reg_rtx
, insn
))
3350 /* Find an assignment that sets reg_used and is available
3351 at the start of the block. */
3352 set
= find_avail_set (regno
, insn
);
3357 /* ??? We might be able to handle PARALLELs. Later. */
3358 if (GET_CODE (pat
) != SET
)
3361 src
= SET_SRC (pat
);
3363 /* Constant propagation. */
3364 if (gcse_constant_p (src
))
3366 if (constprop_register (insn
, reg_used
->reg_rtx
, src
, alter_jumps
))
3370 if (gcse_file
!= NULL
)
3372 fprintf (gcse_file
, "GLOBAL CONST-PROP: Replacing reg %d in ", regno
);
3373 fprintf (gcse_file
, "insn %d with constant ", INSN_UID (insn
));
3374 print_rtl (gcse_file
, src
);
3375 fprintf (gcse_file
, "\n");
3377 if (INSN_DELETED_P (insn
))
3381 else if (REG_P (src
)
3382 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
3383 && REGNO (src
) != regno
)
3385 if (try_replace_reg (reg_used
->reg_rtx
, src
, insn
))
3389 if (gcse_file
!= NULL
)
3391 fprintf (gcse_file
, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
3392 regno
, INSN_UID (insn
));
3393 fprintf (gcse_file
, " with reg %d\n", REGNO (src
));
3396 /* The original insn setting reg_used may or may not now be
3397 deletable. We leave the deletion to flow. */
3398 /* FIXME: If it turns out that the insn isn't deletable,
3399 then we may have unnecessarily extended register lifetimes
3400 and made things worse. */
3408 /* Like find_used_regs, but avoid recording uses that appear in
3409 input-output contexts such as zero_extract or pre_dec. This
3410 restricts the cases we consider to those for which local cprop
3411 can legitimately make replacements. */
3414 local_cprop_find_used_regs (rtx
*xptr
, void *data
)
3421 switch (GET_CODE (x
))
3425 case STRICT_LOW_PART
:
3434 /* Can only legitimately appear this early in the context of
3435 stack pushes for function arguments, but handle all of the
3436 codes nonetheless. */
3440 /* Setting a subreg of a register larger than word_mode leaves
3441 the non-written words unchanged. */
3442 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x
))) > BITS_PER_WORD
)
3450 find_used_regs (xptr
, data
);
3453 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3454 their REG_EQUAL notes need updating. */
3457 do_local_cprop (rtx x
, rtx insn
, int alter_jumps
, rtx
*libcall_sp
)
3459 rtx newreg
= NULL
, newcnst
= NULL
;
3461 /* Rule out USE instructions and ASM statements as we don't want to
3462 change the hard registers mentioned. */
3464 && (REGNO (x
) >= FIRST_PSEUDO_REGISTER
3465 || (GET_CODE (PATTERN (insn
)) != USE
3466 && asm_noperands (PATTERN (insn
)) < 0)))
3468 cselib_val
*val
= cselib_lookup (x
, GET_MODE (x
), 0);
3469 struct elt_loc_list
*l
;
3473 for (l
= val
->locs
; l
; l
= l
->next
)
3475 rtx this_rtx
= l
->loc
;
3481 if (gcse_constant_p (this_rtx
))
3483 if (REG_P (this_rtx
) && REGNO (this_rtx
) >= FIRST_PSEUDO_REGISTER
3484 /* Don't copy propagate if it has attached REG_EQUIV note.
3485 At this point this only function parameters should have
3486 REG_EQUIV notes and if the argument slot is used somewhere
3487 explicitly, it means address of parameter has been taken,
3488 so we should not extend the lifetime of the pseudo. */
3489 && (!(note
= find_reg_note (l
->setting_insn
, REG_EQUIV
, NULL_RTX
))
3490 || ! MEM_P (XEXP (note
, 0))))
3493 if (newcnst
&& constprop_register (insn
, x
, newcnst
, alter_jumps
))
3495 /* If we find a case where we can't fix the retval REG_EQUAL notes
3496 match the new register, we either have to abandon this replacement
3497 or fix delete_trivially_dead_insns to preserve the setting insn,
3498 or make it delete the REG_EUAQL note, and fix up all passes that
3499 require the REG_EQUAL note there. */
3500 if (!adjust_libcall_notes (x
, newcnst
, insn
, libcall_sp
))
3502 if (gcse_file
!= NULL
)
3504 fprintf (gcse_file
, "LOCAL CONST-PROP: Replacing reg %d in ",
3506 fprintf (gcse_file
, "insn %d with constant ",
3508 print_rtl (gcse_file
, newcnst
);
3509 fprintf (gcse_file
, "\n");
3514 else if (newreg
&& newreg
!= x
&& try_replace_reg (x
, newreg
, insn
))
3516 adjust_libcall_notes (x
, newreg
, insn
, libcall_sp
);
3517 if (gcse_file
!= NULL
)
3520 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
3521 REGNO (x
), INSN_UID (insn
));
3522 fprintf (gcse_file
, " with reg %d\n", REGNO (newreg
));
3531 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3532 their REG_EQUAL notes need updating to reflect that OLDREG has been
3533 replaced with NEWVAL in INSN. Return true if all substitutions could
3536 adjust_libcall_notes (rtx oldreg
, rtx newval
, rtx insn
, rtx
*libcall_sp
)
3540 while ((end
= *libcall_sp
++))
3542 rtx note
= find_reg_equal_equiv_note (end
);
3549 if (reg_set_between_p (newval
, PREV_INSN (insn
), end
))
3553 note
= find_reg_equal_equiv_note (end
);
3556 if (reg_mentioned_p (newval
, XEXP (note
, 0)))
3559 while ((end
= *libcall_sp
++));
3563 XEXP (note
, 0) = replace_rtx (XEXP (note
, 0), oldreg
, newval
);
3569 #define MAX_NESTED_LIBCALLS 9
3572 local_cprop_pass (int alter_jumps
)
3575 struct reg_use
*reg_used
;
3576 rtx libcall_stack
[MAX_NESTED_LIBCALLS
+ 1], *libcall_sp
;
3577 bool changed
= false;
3579 cselib_init (false);
3580 libcall_sp
= &libcall_stack
[MAX_NESTED_LIBCALLS
];
3582 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
3586 rtx note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
3590 if (libcall_sp
== libcall_stack
)
3592 *--libcall_sp
= XEXP (note
, 0);
3594 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
3597 note
= find_reg_equal_equiv_note (insn
);
3601 note_uses (&PATTERN (insn
), local_cprop_find_used_regs
, NULL
);
3603 local_cprop_find_used_regs (&XEXP (note
, 0), NULL
);
3605 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
3606 reg_used
++, reg_use_count
--)
3607 if (do_local_cprop (reg_used
->reg_rtx
, insn
, alter_jumps
,
3613 if (INSN_DELETED_P (insn
))
3616 while (reg_use_count
);
3618 cselib_process_insn (insn
);
3621 /* Global analysis may get into infinite loops for unreachable blocks. */
3622 if (changed
&& alter_jumps
)
3624 delete_unreachable_blocks ();
3625 free_reg_set_mem ();
3626 alloc_reg_set_mem (max_reg_num ());
3627 compute_sets (get_insns ());
3631 /* Forward propagate copies. This includes copies and constants. Return
3632 nonzero if a change was made. */
3635 cprop (int alter_jumps
)
3641 /* Note we start at block 1. */
3642 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3644 if (gcse_file
!= NULL
)
3645 fprintf (gcse_file
, "\n");
3650 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
3652 /* Reset tables used to keep track of what's still valid [since the
3653 start of the block]. */
3654 reset_opr_set_tables ();
3656 for (insn
= BB_HEAD (bb
);
3657 insn
!= NULL
&& insn
!= NEXT_INSN (BB_END (bb
));
3658 insn
= NEXT_INSN (insn
))
3661 changed
|= cprop_insn (insn
, alter_jumps
);
3663 /* Keep track of everything modified by this insn. */
3664 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
3665 call mark_oprs_set if we turned the insn into a NOTE. */
3666 if (! NOTE_P (insn
))
3667 mark_oprs_set (insn
);
3671 if (gcse_file
!= NULL
)
3672 fprintf (gcse_file
, "\n");
3677 /* Similar to get_condition, only the resulting condition must be
3678 valid at JUMP, instead of at EARLIEST.
3680 This differs from noce_get_condition in ifcvt.c in that we prefer not to
3681 settle for the condition variable in the jump instruction being integral.
3682 We prefer to be able to record the value of a user variable, rather than
3683 the value of a temporary used in a condition. This could be solved by
3684 recording the value of *every* register scaned by canonicalize_condition,
3685 but this would require some code reorganization. */
3688 fis_get_condition (rtx jump
)
3690 return get_condition (jump
, NULL
, false, true);
3693 /* Check the comparison COND to see if we can safely form an implicit set from
3694 it. COND is either an EQ or NE comparison. */
3697 implicit_set_cond_p (rtx cond
)
3699 enum machine_mode mode
= GET_MODE (XEXP (cond
, 0));
3700 rtx cst
= XEXP (cond
, 1);
3702 /* We can't perform this optimization if either operand might be or might
3703 contain a signed zero. */
3704 if (HONOR_SIGNED_ZEROS (mode
))
3706 /* It is sufficient to check if CST is or contains a zero. We must
3707 handle float, complex, and vector. If any subpart is a zero, then
3708 the optimization can't be performed. */
3709 /* ??? The complex and vector checks are not implemented yet. We just
3710 always return zero for them. */
3711 if (GET_CODE (cst
) == CONST_DOUBLE
)
3714 REAL_VALUE_FROM_CONST_DOUBLE (d
, cst
);
3715 if (REAL_VALUES_EQUAL (d
, dconst0
))
3722 return gcse_constant_p (cst
);
3725 /* Find the implicit sets of a function. An "implicit set" is a constraint
3726 on the value of a variable, implied by a conditional jump. For example,
3727 following "if (x == 2)", the then branch may be optimized as though the
3728 conditional performed an "explicit set", in this example, "x = 2". This
3729 function records the set patterns that are implicit at the start of each
3733 find_implicit_sets (void)
3735 basic_block bb
, dest
;
3741 /* Check for more than one successor. */
3742 if (EDGE_COUNT (bb
->succs
) > 1)
3744 cond
= fis_get_condition (BB_END (bb
));
3747 && (GET_CODE (cond
) == EQ
|| GET_CODE (cond
) == NE
)
3748 && REG_P (XEXP (cond
, 0))
3749 && REGNO (XEXP (cond
, 0)) >= FIRST_PSEUDO_REGISTER
3750 && implicit_set_cond_p (cond
))
3752 dest
= GET_CODE (cond
) == EQ
? BRANCH_EDGE (bb
)->dest
3753 : FALLTHRU_EDGE (bb
)->dest
;
3755 if (dest
&& EDGE_COUNT (dest
->preds
) == 1
3756 && dest
!= EXIT_BLOCK_PTR
)
3758 new = gen_rtx_SET (VOIDmode
, XEXP (cond
, 0),
3760 implicit_sets
[dest
->index
] = new;
3763 fprintf(gcse_file
, "Implicit set of reg %d in ",
3764 REGNO (XEXP (cond
, 0)));
3765 fprintf(gcse_file
, "basic block %d\n", dest
->index
);
3773 fprintf (gcse_file
, "Found %d implicit sets\n", count
);
3776 /* Perform one copy/constant propagation pass.
3777 PASS is the pass count. If CPROP_JUMPS is true, perform constant
3778 propagation into conditional jumps. If BYPASS_JUMPS is true,
3779 perform conditional jump bypassing optimizations. */
3782 one_cprop_pass (int pass
, int cprop_jumps
, int bypass_jumps
)
3786 const_prop_count
= 0;
3787 copy_prop_count
= 0;
3789 local_cprop_pass (cprop_jumps
);
3791 /* Determine implicit sets. */
3792 implicit_sets
= xcalloc (last_basic_block
, sizeof (rtx
));
3793 find_implicit_sets ();
3795 alloc_hash_table (max_cuid
, &set_hash_table
, 1);
3796 compute_hash_table (&set_hash_table
);
3798 /* Free implicit_sets before peak usage. */
3799 free (implicit_sets
);
3800 implicit_sets
= NULL
;
3803 dump_hash_table (gcse_file
, "SET", &set_hash_table
);
3804 if (set_hash_table
.n_elems
> 0)
3806 alloc_cprop_mem (last_basic_block
, set_hash_table
.n_elems
);
3807 compute_cprop_data ();
3808 changed
= cprop (cprop_jumps
);
3810 changed
|= bypass_conditional_jumps ();
3814 free_hash_table (&set_hash_table
);
3818 fprintf (gcse_file
, "CPROP of %s, pass %d: %d bytes needed, ",
3819 current_function_name (), pass
, bytes_used
);
3820 fprintf (gcse_file
, "%d const props, %d copy props\n\n",
3821 const_prop_count
, copy_prop_count
);
3823 /* Global analysis may get into infinite loops for unreachable blocks. */
3824 if (changed
&& cprop_jumps
)
3825 delete_unreachable_blocks ();
3830 /* Bypass conditional jumps. */
3832 /* The value of last_basic_block at the beginning of the jump_bypass
3833 pass. The use of redirect_edge_and_branch_force may introduce new
3834 basic blocks, but the data flow analysis is only valid for basic
3835 block indices less than bypass_last_basic_block. */
3837 static int bypass_last_basic_block
;
3839 /* Find a set of REGNO to a constant that is available at the end of basic
3840 block BB. Returns NULL if no such set is found. Based heavily upon
3843 static struct expr
*
3844 find_bypass_set (int regno
, int bb
)
3846 struct expr
*result
= 0;
3851 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
3855 if (TEST_BIT (cprop_avout
[bb
], set
->bitmap_index
))
3857 set
= next_set (regno
, set
);
3863 if (GET_CODE (set
->expr
) != SET
)
3866 src
= SET_SRC (set
->expr
);
3867 if (gcse_constant_p (src
))
3873 regno
= REGNO (src
);
3879 /* Subroutine of bypass_block that checks whether a pseudo is killed by
3880 any of the instructions inserted on an edge. Jump bypassing places
3881 condition code setters on CFG edges using insert_insn_on_edge. This
3882 function is required to check that our data flow analysis is still
3883 valid prior to commit_edge_insertions. */
3886 reg_killed_on_edge (rtx reg
, edge e
)
3890 for (insn
= e
->insns
.r
; insn
; insn
= NEXT_INSN (insn
))
3891 if (INSN_P (insn
) && reg_set_p (reg
, insn
))
3897 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
3898 basic block BB which has more than one predecessor. If not NULL, SETCC
3899 is the first instruction of BB, which is immediately followed by JUMP_INSN
3900 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
3901 Returns nonzero if a change was made.
3903 During the jump bypassing pass, we may place copies of SETCC instructions
3904 on CFG edges. The following routine must be careful to pay attention to
3905 these inserted insns when performing its transformations. */
3908 bypass_block (basic_block bb
, rtx setcc
, rtx jump
)
3913 int may_be_loop_header
;
3915 insn
= (setcc
!= NULL
) ? setcc
: jump
;
3917 /* Determine set of register uses in INSN. */
3919 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
3920 note
= find_reg_equal_equiv_note (insn
);
3922 find_used_regs (&XEXP (note
, 0), NULL
);
3924 may_be_loop_header
= false;
3926 FOR_EACH_EDGE (e
, bb
->preds
)
3928 if (e
->flags
& EDGE_DFS_BACK
)
3930 may_be_loop_header
= true;
3937 FOR_EACH_EDGE (e
, bb
->preds
)
3939 if (e
->flags
& EDGE_COMPLEX
)
3942 /* We can't redirect edges from new basic blocks. */
3943 if (e
->src
->index
>= bypass_last_basic_block
)
3946 /* The irreducible loops created by redirecting of edges entering the
3947 loop from outside would decrease effectiveness of some of the following
3948 optimizations, so prevent this. */
3949 if (may_be_loop_header
3950 && !(e
->flags
& EDGE_DFS_BACK
))
3953 for (i
= 0; i
< reg_use_count
; i
++)
3955 struct reg_use
*reg_used
= ®_use_table
[i
];
3956 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
3957 basic_block dest
, old_dest
;
3961 if (regno
>= max_gcse_regno
)
3964 set
= find_bypass_set (regno
, e
->src
->index
);
3969 /* Check the data flow is valid after edge insertions. */
3970 if (e
->insns
.r
&& reg_killed_on_edge (reg_used
->reg_rtx
, e
))
3973 src
= SET_SRC (pc_set (jump
));
3976 src
= simplify_replace_rtx (src
,
3977 SET_DEST (PATTERN (setcc
)),
3978 SET_SRC (PATTERN (setcc
)));
3980 new = simplify_replace_rtx (src
, reg_used
->reg_rtx
,
3981 SET_SRC (set
->expr
));
3983 /* Jump bypassing may have already placed instructions on
3984 edges of the CFG. We can't bypass an outgoing edge that
3985 has instructions associated with it, as these insns won't
3986 get executed if the incoming edge is redirected. */
3990 edest
= FALLTHRU_EDGE (bb
);
3991 dest
= edest
->insns
.r
? NULL
: edest
->dest
;
3993 else if (GET_CODE (new) == LABEL_REF
)
3995 dest
= BLOCK_FOR_INSN (XEXP (new, 0));
3996 /* Don't bypass edges containing instructions. */
3997 FOR_EACH_EDGE (edest
, bb
->succs
)
3999 if (edest
->dest
== dest
&& edest
->insns
.r
)
4010 /* Avoid unification of the edge with other edges from original
4011 branch. We would end up emitting the instruction on "both"
4014 if (dest
&& setcc
&& !CC0_P (SET_DEST (PATTERN (setcc
))))
4017 FOR_EACH_EDGE (e2
, e
->src
->succs
)
4019 if (e2
->dest
== dest
)
4031 && dest
!= EXIT_BLOCK_PTR
)
4033 redirect_edge_and_branch_force (e
, dest
);
4035 /* Copy the register setter to the redirected edge.
4036 Don't copy CC0 setters, as CC0 is dead after jump. */
4039 rtx pat
= PATTERN (setcc
);
4040 if (!CC0_P (SET_DEST (pat
)))
4041 insert_insn_on_edge (copy_insn (pat
), e
);
4044 if (gcse_file
!= NULL
)
4046 fprintf (gcse_file
, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
4047 regno
, INSN_UID (jump
));
4048 print_rtl (gcse_file
, SET_SRC (set
->expr
));
4049 fprintf (gcse_file
, "\nBypass edge from %d->%d to %d\n",
4050 e
->src
->index
, old_dest
->index
, dest
->index
);
4061 /* Find basic blocks with more than one predecessor that only contain a
4062 single conditional jump. If the result of the comparison is known at
4063 compile-time from any incoming edge, redirect that edge to the
4064 appropriate target. Returns nonzero if a change was made.
4066 This function is now mis-named, because we also handle indirect jumps. */
4069 bypass_conditional_jumps (void)
4077 /* Note we start at block 1. */
4078 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
4081 bypass_last_basic_block
= last_basic_block
;
4082 mark_dfs_back_edges ();
4085 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
,
4086 EXIT_BLOCK_PTR
, next_bb
)
4088 /* Check for more than one predecessor. */
4089 if (EDGE_COUNT (bb
->preds
) > 1)
4092 for (insn
= BB_HEAD (bb
);
4093 insn
!= NULL
&& insn
!= NEXT_INSN (BB_END (bb
));
4094 insn
= NEXT_INSN (insn
))
4095 if (NONJUMP_INSN_P (insn
))
4099 if (GET_CODE (PATTERN (insn
)) != SET
)
4102 dest
= SET_DEST (PATTERN (insn
));
4103 if (REG_P (dest
) || CC0_P (dest
))
4108 else if (JUMP_P (insn
))
4110 if ((any_condjump_p (insn
) || computed_jump_p (insn
))
4111 && onlyjump_p (insn
))
4112 changed
|= bypass_block (bb
, setcc
, insn
);
4115 else if (INSN_P (insn
))
4120 /* If we bypassed any register setting insns, we inserted a
4121 copy on the redirected edge. These need to be committed. */
4123 commit_edge_insertions();
4128 /* Compute PRE+LCM working variables. */
4130 /* Local properties of expressions. */
4131 /* Nonzero for expressions that are transparent in the block. */
4132 static sbitmap
*transp
;
4134 /* Nonzero for expressions that are transparent at the end of the block.
4135 This is only zero for expressions killed by abnormal critical edge
4136 created by a calls. */
4137 static sbitmap
*transpout
;
4139 /* Nonzero for expressions that are computed (available) in the block. */
4140 static sbitmap
*comp
;
4142 /* Nonzero for expressions that are locally anticipatable in the block. */
4143 static sbitmap
*antloc
;
4145 /* Nonzero for expressions where this block is an optimal computation
4147 static sbitmap
*pre_optimal
;
4149 /* Nonzero for expressions which are redundant in a particular block. */
4150 static sbitmap
*pre_redundant
;
4152 /* Nonzero for expressions which should be inserted on a specific edge. */
4153 static sbitmap
*pre_insert_map
;
4155 /* Nonzero for expressions which should be deleted in a specific block. */
4156 static sbitmap
*pre_delete_map
;
4158 /* Contains the edge_list returned by pre_edge_lcm. */
4159 static struct edge_list
*edge_list
;
4161 /* Redundant insns. */
4162 static sbitmap pre_redundant_insns
;
4164 /* Allocate vars used for PRE analysis. */
4167 alloc_pre_mem (int n_blocks
, int n_exprs
)
4169 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4170 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4171 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4174 pre_redundant
= NULL
;
4175 pre_insert_map
= NULL
;
4176 pre_delete_map
= NULL
;
4177 ae_kill
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4179 /* pre_insert and pre_delete are allocated later. */
4182 /* Free vars used for PRE analysis. */
4187 sbitmap_vector_free (transp
);
4188 sbitmap_vector_free (comp
);
4190 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
4193 sbitmap_vector_free (pre_optimal
);
4195 sbitmap_vector_free (pre_redundant
);
4197 sbitmap_vector_free (pre_insert_map
);
4199 sbitmap_vector_free (pre_delete_map
);
4201 transp
= comp
= NULL
;
4202 pre_optimal
= pre_redundant
= pre_insert_map
= pre_delete_map
= NULL
;
4205 /* Top level routine to do the dataflow analysis needed by PRE. */
4208 compute_pre_data (void)
4210 sbitmap trapping_expr
;
4214 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
4215 sbitmap_vector_zero (ae_kill
, last_basic_block
);
4217 /* Collect expressions which might trap. */
4218 trapping_expr
= sbitmap_alloc (expr_hash_table
.n_elems
);
4219 sbitmap_zero (trapping_expr
);
4220 for (ui
= 0; ui
< expr_hash_table
.size
; ui
++)
4223 for (e
= expr_hash_table
.table
[ui
]; e
!= NULL
; e
= e
->next_same_hash
)
4224 if (may_trap_p (e
->expr
))
4225 SET_BIT (trapping_expr
, e
->bitmap_index
);
4228 /* Compute ae_kill for each basic block using:
4237 /* If the current block is the destination of an abnormal edge, we
4238 kill all trapping expressions because we won't be able to properly
4239 place the instruction on the edge. So make them neither
4240 anticipatable nor transparent. This is fairly conservative. */
4241 FOR_EACH_EDGE (e
, bb
->preds
)
4243 if (e
->flags
& EDGE_ABNORMAL
)
4245 sbitmap_difference (antloc
[bb
->index
], antloc
[bb
->index
], trapping_expr
);
4246 sbitmap_difference (transp
[bb
->index
], transp
[bb
->index
], trapping_expr
);
4252 sbitmap_a_or_b (ae_kill
[bb
->index
], transp
[bb
->index
], comp
[bb
->index
]);
4253 sbitmap_not (ae_kill
[bb
->index
], ae_kill
[bb
->index
]);
4256 edge_list
= pre_edge_lcm (gcse_file
, expr_hash_table
.n_elems
, transp
, comp
, antloc
,
4257 ae_kill
, &pre_insert_map
, &pre_delete_map
);
4258 sbitmap_vector_free (antloc
);
4260 sbitmap_vector_free (ae_kill
);
4262 sbitmap_free (trapping_expr
);
4267 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
4270 VISITED is a pointer to a working buffer for tracking which BB's have
4271 been visited. It is NULL for the top-level call.
4273 We treat reaching expressions that go through blocks containing the same
4274 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
4275 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
4276 2 as not reaching. The intent is to improve the probability of finding
4277 only one reaching expression and to reduce register lifetimes by picking
4278 the closest such expression. */
4281 pre_expr_reaches_here_p_work (basic_block occr_bb
, struct expr
*expr
, basic_block bb
, char *visited
)
4285 FOR_EACH_EDGE (pred
, bb
->preds
)
4287 basic_block pred_bb
= pred
->src
;
4289 if (pred
->src
== ENTRY_BLOCK_PTR
4290 /* Has predecessor has already been visited? */
4291 || visited
[pred_bb
->index
])
4292 ;/* Nothing to do. */
4294 /* Does this predecessor generate this expression? */
4295 else if (TEST_BIT (comp
[pred_bb
->index
], expr
->bitmap_index
))
4297 /* Is this the occurrence we're looking for?
4298 Note that there's only one generating occurrence per block
4299 so we just need to check the block number. */
4300 if (occr_bb
== pred_bb
)
4303 visited
[pred_bb
->index
] = 1;
4305 /* Ignore this predecessor if it kills the expression. */
4306 else if (! TEST_BIT (transp
[pred_bb
->index
], expr
->bitmap_index
))
4307 visited
[pred_bb
->index
] = 1;
4309 /* Neither gen nor kill. */
4312 visited
[pred_bb
->index
] = 1;
4313 if (pre_expr_reaches_here_p_work (occr_bb
, expr
, pred_bb
, visited
))
4319 /* All paths have been checked. */
4323 /* The wrapper for pre_expr_reaches_here_work that ensures that any
4324 memory allocated for that function is returned. */
4327 pre_expr_reaches_here_p (basic_block occr_bb
, struct expr
*expr
, basic_block bb
)
4330 char *visited
= xcalloc (last_basic_block
, 1);
4332 rval
= pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
);
4339 /* Given an expr, generate RTL which we can insert at the end of a BB,
4340 or on an edge. Set the block number of any insns generated to
4344 process_insert_insn (struct expr
*expr
)
4346 rtx reg
= expr
->reaching_reg
;
4347 rtx exp
= copy_rtx (expr
->expr
);
4352 /* If the expression is something that's an operand, like a constant,
4353 just copy it to a register. */
4354 if (general_operand (exp
, GET_MODE (reg
)))
4355 emit_move_insn (reg
, exp
);
4357 /* Otherwise, make a new insn to compute this expression and make sure the
4358 insn will be recognized (this also adds any needed CLOBBERs). Copy the
4359 expression to make sure we don't have any sharing issues. */
4360 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode
, reg
, exp
))))
4369 /* Add EXPR to the end of basic block BB.
4371 This is used by both the PRE and code hoisting.
4373 For PRE, we want to verify that the expr is either transparent
4374 or locally anticipatable in the target block. This check makes
4375 no sense for code hoisting. */
4378 insert_insn_end_bb (struct expr
*expr
, basic_block bb
, int pre
)
4380 rtx insn
= BB_END (bb
);
4382 rtx reg
= expr
->reaching_reg
;
4383 int regno
= REGNO (reg
);
4386 pat
= process_insert_insn (expr
);
4387 if (pat
== NULL_RTX
|| ! INSN_P (pat
))
4391 while (NEXT_INSN (pat_end
) != NULL_RTX
)
4392 pat_end
= NEXT_INSN (pat_end
);
4394 /* If the last insn is a jump, insert EXPR in front [taking care to
4395 handle cc0, etc. properly]. Similarly we need to care trapping
4396 instructions in presence of non-call exceptions. */
4399 || (NONJUMP_INSN_P (insn
)
4400 && (EDGE_COUNT (bb
->succs
) > 1
4401 || EDGE_SUCC (bb
, 0)->flags
& EDGE_ABNORMAL
)))
4406 /* It should always be the case that we can put these instructions
4407 anywhere in the basic block with performing PRE optimizations.
4409 if (NONJUMP_INSN_P (insn
) && pre
4410 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
4411 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
4414 /* If this is a jump table, then we can't insert stuff here. Since
4415 we know the previous real insn must be the tablejump, we insert
4416 the new instruction just before the tablejump. */
4417 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
4418 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
4419 insn
= prev_real_insn (insn
);
4422 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4423 if cc0 isn't set. */
4424 note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
4426 insn
= XEXP (note
, 0);
4429 rtx maybe_cc0_setter
= prev_nonnote_insn (insn
);
4430 if (maybe_cc0_setter
4431 && INSN_P (maybe_cc0_setter
)
4432 && sets_cc0_p (PATTERN (maybe_cc0_setter
)))
4433 insn
= maybe_cc0_setter
;
4436 /* FIXME: What if something in cc0/jump uses value set in new insn? */
4437 new_insn
= emit_insn_before (pat
, insn
);
4440 /* Likewise if the last insn is a call, as will happen in the presence
4441 of exception handling. */
4442 else if (CALL_P (insn
)
4443 && (EDGE_COUNT (bb
->succs
) > 1 || EDGE_SUCC (bb
, 0)->flags
& EDGE_ABNORMAL
))
4445 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
4446 we search backward and place the instructions before the first
4447 parameter is loaded. Do this for everyone for consistency and a
4448 presumption that we'll get better code elsewhere as well.
4450 It should always be the case that we can put these instructions
4451 anywhere in the basic block with performing PRE optimizations.
4455 && !TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
4456 && !TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
))
4459 /* Since different machines initialize their parameter registers
4460 in different orders, assume nothing. Collect the set of all
4461 parameter registers. */
4462 insn
= find_first_parameter_load (insn
, BB_HEAD (bb
));
4464 /* If we found all the parameter loads, then we want to insert
4465 before the first parameter load.
4467 If we did not find all the parameter loads, then we might have
4468 stopped on the head of the block, which could be a CODE_LABEL.
4469 If we inserted before the CODE_LABEL, then we would be putting
4470 the insn in the wrong basic block. In that case, put the insn
4471 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
4472 while (LABEL_P (insn
)
4473 || NOTE_INSN_BASIC_BLOCK_P (insn
))
4474 insn
= NEXT_INSN (insn
);
4476 new_insn
= emit_insn_before (pat
, insn
);
4479 new_insn
= emit_insn_after (pat
, insn
);
4485 add_label_notes (PATTERN (pat
), new_insn
);
4486 note_stores (PATTERN (pat
), record_set_info
, pat
);
4490 pat
= NEXT_INSN (pat
);
4493 gcse_create_count
++;
4497 fprintf (gcse_file
, "PRE/HOIST: end of bb %d, insn %d, ",
4498 bb
->index
, INSN_UID (new_insn
));
4499 fprintf (gcse_file
, "copying expression %d to reg %d\n",
4500 expr
->bitmap_index
, regno
);
4504 /* Insert partially redundant expressions on edges in the CFG to make
4505 the expressions fully redundant. */
4508 pre_edge_insert (struct edge_list
*edge_list
, struct expr
**index_map
)
4510 int e
, i
, j
, num_edges
, set_size
, did_insert
= 0;
4513 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
4514 if it reaches any of the deleted expressions. */
4516 set_size
= pre_insert_map
[0]->size
;
4517 num_edges
= NUM_EDGES (edge_list
);
4518 inserted
= sbitmap_vector_alloc (num_edges
, expr_hash_table
.n_elems
);
4519 sbitmap_vector_zero (inserted
, num_edges
);
4521 for (e
= 0; e
< num_edges
; e
++)
4524 basic_block bb
= INDEX_EDGE_PRED_BB (edge_list
, e
);
4526 for (i
= indx
= 0; i
< set_size
; i
++, indx
+= SBITMAP_ELT_BITS
)
4528 SBITMAP_ELT_TYPE insert
= pre_insert_map
[e
]->elms
[i
];
4530 for (j
= indx
; insert
&& j
< (int) expr_hash_table
.n_elems
; j
++, insert
>>= 1)
4531 if ((insert
& 1) != 0 && index_map
[j
]->reaching_reg
!= NULL_RTX
)
4533 struct expr
*expr
= index_map
[j
];
4536 /* Now look at each deleted occurrence of this expression. */
4537 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4539 if (! occr
->deleted_p
)
4542 /* Insert this expression on this edge if if it would
4543 reach the deleted occurrence in BB. */
4544 if (!TEST_BIT (inserted
[e
], j
))
4547 edge eg
= INDEX_EDGE (edge_list
, e
);
4549 /* We can't insert anything on an abnormal and
4550 critical edge, so we insert the insn at the end of
4551 the previous block. There are several alternatives
4552 detailed in Morgans book P277 (sec 10.5) for
4553 handling this situation. This one is easiest for
4556 if ((eg
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
4557 insert_insn_end_bb (index_map
[j
], bb
, 0);
4560 insn
= process_insert_insn (index_map
[j
]);
4561 insert_insn_on_edge (insn
, eg
);
4566 fprintf (gcse_file
, "PRE/HOIST: edge (%d,%d), ",
4568 INDEX_EDGE_SUCC_BB (edge_list
, e
)->index
);
4569 fprintf (gcse_file
, "copy expression %d\n",
4570 expr
->bitmap_index
);
4573 update_ld_motion_stores (expr
);
4574 SET_BIT (inserted
[e
], j
);
4576 gcse_create_count
++;
4583 sbitmap_vector_free (inserted
);
4587 /* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
4588 Given "old_reg <- expr" (INSN), instead of adding after it
4589 reaching_reg <- old_reg
4590 it's better to do the following:
4591 reaching_reg <- expr
4592 old_reg <- reaching_reg
4593 because this way copy propagation can discover additional PRE
4594 opportunities. But if this fails, we try the old way.
4595 When "expr" is a store, i.e.
4596 given "MEM <- old_reg", instead of adding after it
4597 reaching_reg <- old_reg
4598 it's better to add it before as follows:
4599 reaching_reg <- old_reg
4600 MEM <- reaching_reg. */
4603 pre_insert_copy_insn (struct expr
*expr
, rtx insn
)
4605 rtx reg
= expr
->reaching_reg
;
4606 int regno
= REGNO (reg
);
4607 int indx
= expr
->bitmap_index
;
4608 rtx pat
= PATTERN (insn
);
4613 /* This block matches the logic in hash_scan_insn. */
4614 if (GET_CODE (pat
) == SET
)
4616 else if (GET_CODE (pat
) == PARALLEL
)
4618 /* Search through the parallel looking for the set whose
4619 source was the expression that we're interested in. */
4621 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
4623 rtx x
= XVECEXP (pat
, 0, i
);
4624 if (GET_CODE (x
) == SET
4625 && expr_equiv_p (SET_SRC (x
), expr
->expr
))
4635 if (REG_P (SET_DEST (set
)))
4637 old_reg
= SET_DEST (set
);
4638 /* Check if we can modify the set destination in the original insn. */
4639 if (validate_change (insn
, &SET_DEST (set
), reg
, 0))
4641 new_insn
= gen_move_insn (old_reg
, reg
);
4642 new_insn
= emit_insn_after (new_insn
, insn
);
4644 /* Keep register set table up to date. */
4645 replace_one_set (REGNO (old_reg
), insn
, new_insn
);
4646 record_one_set (regno
, insn
);
4650 new_insn
= gen_move_insn (reg
, old_reg
);
4651 new_insn
= emit_insn_after (new_insn
, insn
);
4653 /* Keep register set table up to date. */
4654 record_one_set (regno
, new_insn
);
4657 else /* This is possible only in case of a store to memory. */
4659 old_reg
= SET_SRC (set
);
4660 new_insn
= gen_move_insn (reg
, old_reg
);
4662 /* Check if we can modify the set source in the original insn. */
4663 if (validate_change (insn
, &SET_SRC (set
), reg
, 0))
4664 new_insn
= emit_insn_before (new_insn
, insn
);
4666 new_insn
= emit_insn_after (new_insn
, insn
);
4668 /* Keep register set table up to date. */
4669 record_one_set (regno
, new_insn
);
4672 gcse_create_count
++;
4676 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
4677 BLOCK_NUM (insn
), INSN_UID (new_insn
), indx
,
4678 INSN_UID (insn
), regno
);
4681 /* Copy available expressions that reach the redundant expression
4682 to `reaching_reg'. */
4685 pre_insert_copies (void)
4687 unsigned int i
, added_copy
;
4692 /* For each available expression in the table, copy the result to
4693 `reaching_reg' if the expression reaches a deleted one.
4695 ??? The current algorithm is rather brute force.
4696 Need to do some profiling. */
4698 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4699 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
4701 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
4702 we don't want to insert a copy here because the expression may not
4703 really be redundant. So only insert an insn if the expression was
4704 deleted. This test also avoids further processing if the
4705 expression wasn't deleted anywhere. */
4706 if (expr
->reaching_reg
== NULL
)
4709 /* Set when we add a copy for that expression. */
4712 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4714 if (! occr
->deleted_p
)
4717 for (avail
= expr
->avail_occr
; avail
!= NULL
; avail
= avail
->next
)
4719 rtx insn
= avail
->insn
;
4721 /* No need to handle this one if handled already. */
4722 if (avail
->copied_p
)
4725 /* Don't handle this one if it's a redundant one. */
4726 if (TEST_BIT (pre_redundant_insns
, INSN_CUID (insn
)))
4729 /* Or if the expression doesn't reach the deleted one. */
4730 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail
->insn
),
4732 BLOCK_FOR_INSN (occr
->insn
)))
4737 /* Copy the result of avail to reaching_reg. */
4738 pre_insert_copy_insn (expr
, insn
);
4739 avail
->copied_p
= 1;
4744 update_ld_motion_stores (expr
);
4748 /* Emit move from SRC to DEST noting the equivalence with expression computed
4751 gcse_emit_move_after (rtx src
, rtx dest
, rtx insn
)
4754 rtx set
= single_set (insn
), set2
;
4758 /* This should never fail since we're creating a reg->reg copy
4759 we've verified to be valid. */
4761 new = emit_insn_after (gen_move_insn (dest
, src
), insn
);
4763 /* Note the equivalence for local CSE pass. */
4764 set2
= single_set (new);
4765 if (!set2
|| !rtx_equal_p (SET_DEST (set2
), dest
))
4767 if ((note
= find_reg_equal_equiv_note (insn
)))
4768 eqv
= XEXP (note
, 0);
4770 eqv
= SET_SRC (set
);
4772 set_unique_reg_note (new, REG_EQUAL
, copy_insn_1 (eqv
));
4777 /* Delete redundant computations.
4778 Deletion is done by changing the insn to copy the `reaching_reg' of
4779 the expression into the result of the SET. It is left to later passes
4780 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
4782 Returns nonzero if a change is made. */
4793 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4794 for (expr
= expr_hash_table
.table
[i
];
4796 expr
= expr
->next_same_hash
)
4798 int indx
= expr
->bitmap_index
;
4800 /* We only need to search antic_occr since we require
4803 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4805 rtx insn
= occr
->insn
;
4807 basic_block bb
= BLOCK_FOR_INSN (insn
);
4809 /* We only delete insns that have a single_set. */
4810 if (TEST_BIT (pre_delete_map
[bb
->index
], indx
)
4811 && (set
= single_set (insn
)) != 0)
4813 /* Create a pseudo-reg to store the result of reaching
4814 expressions into. Get the mode for the new pseudo from
4815 the mode of the original destination pseudo. */
4816 if (expr
->reaching_reg
== NULL
)
4818 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
4820 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
4822 occr
->deleted_p
= 1;
4823 SET_BIT (pre_redundant_insns
, INSN_CUID (insn
));
4830 "PRE: redundant insn %d (expression %d) in ",
4831 INSN_UID (insn
), indx
);
4832 fprintf (gcse_file
, "bb %d, reaching reg is %d\n",
4833 bb
->index
, REGNO (expr
->reaching_reg
));
4842 /* Perform GCSE optimizations using PRE.
4843 This is called by one_pre_gcse_pass after all the dataflow analysis
4846 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
4847 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
4848 Compiler Design and Implementation.
4850 ??? A new pseudo reg is created to hold the reaching expression. The nice
4851 thing about the classical approach is that it would try to use an existing
4852 reg. If the register can't be adequately optimized [i.e. we introduce
4853 reload problems], one could add a pass here to propagate the new register
4856 ??? We don't handle single sets in PARALLELs because we're [currently] not
4857 able to copy the rest of the parallel when we insert copies to create full
4858 redundancies from partial redundancies. However, there's no reason why we
4859 can't handle PARALLELs in the cases where there are no partial
4866 int did_insert
, changed
;
4867 struct expr
**index_map
;
4870 /* Compute a mapping from expression number (`bitmap_index') to
4871 hash table entry. */
4873 index_map
= xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
4874 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4875 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
4876 index_map
[expr
->bitmap_index
] = expr
;
4878 /* Reset bitmap used to track which insns are redundant. */
4879 pre_redundant_insns
= sbitmap_alloc (max_cuid
);
4880 sbitmap_zero (pre_redundant_insns
);
4882 /* Delete the redundant insns first so that
4883 - we know what register to use for the new insns and for the other
4884 ones with reaching expressions
4885 - we know which insns are redundant when we go to create copies */
4887 changed
= pre_delete ();
4889 did_insert
= pre_edge_insert (edge_list
, index_map
);
4891 /* In other places with reaching expressions, copy the expression to the
4892 specially allocated pseudo-reg that reaches the redundant expr. */
4893 pre_insert_copies ();
4896 commit_edge_insertions ();
4901 sbitmap_free (pre_redundant_insns
);
4905 /* Top level routine to perform one PRE GCSE pass.
4907 Return nonzero if a change was made. */
4910 one_pre_gcse_pass (int pass
)
4914 gcse_subst_count
= 0;
4915 gcse_create_count
= 0;
4917 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
4918 add_noreturn_fake_exit_edges ();
4920 compute_ld_motion_mems ();
4922 compute_hash_table (&expr_hash_table
);
4923 trim_ld_motion_mems ();
4925 dump_hash_table (gcse_file
, "Expression", &expr_hash_table
);
4927 if (expr_hash_table
.n_elems
> 0)
4929 alloc_pre_mem (last_basic_block
, expr_hash_table
.n_elems
);
4930 compute_pre_data ();
4931 changed
|= pre_gcse ();
4932 free_edge_list (edge_list
);
4937 remove_fake_exit_edges ();
4938 free_hash_table (&expr_hash_table
);
4942 fprintf (gcse_file
, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
4943 current_function_name (), pass
, bytes_used
);
4944 fprintf (gcse_file
, "%d substs, %d insns created\n",
4945 gcse_subst_count
, gcse_create_count
);
4951 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
4952 If notes are added to an insn which references a CODE_LABEL, the
4953 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
4954 because the following loop optimization pass requires them. */
4956 /* ??? This is very similar to the loop.c add_label_notes function. We
4957 could probably share code here. */
4959 /* ??? If there was a jump optimization pass after gcse and before loop,
4960 then we would not need to do this here, because jump would add the
4961 necessary REG_LABEL notes. */
4964 add_label_notes (rtx x
, rtx insn
)
4966 enum rtx_code code
= GET_CODE (x
);
4970 if (code
== LABEL_REF
&& !LABEL_REF_NONLOCAL_P (x
))
4972 /* This code used to ignore labels that referred to dispatch tables to
4973 avoid flow generating (slightly) worse code.
4975 We no longer ignore such label references (see LABEL_REF handling in
4976 mark_jump_label for additional information). */
4978 REG_NOTES (insn
) = gen_rtx_INSN_LIST (REG_LABEL
, XEXP (x
, 0),
4980 if (LABEL_P (XEXP (x
, 0)))
4981 LABEL_NUSES (XEXP (x
, 0))++;
4985 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
4988 add_label_notes (XEXP (x
, i
), insn
);
4989 else if (fmt
[i
] == 'E')
4990 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4991 add_label_notes (XVECEXP (x
, i
, j
), insn
);
4995 /* Compute transparent outgoing information for each block.
4997 An expression is transparent to an edge unless it is killed by
4998 the edge itself. This can only happen with abnormal control flow,
4999 when the edge is traversed through a call. This happens with
5000 non-local labels and exceptions.
5002 This would not be necessary if we split the edge. While this is
5003 normally impossible for abnormal critical edges, with some effort
5004 it should be possible with exception handling, since we still have
5005 control over which handler should be invoked. But due to increased
5006 EH table sizes, this may not be worthwhile. */
5009 compute_transpout (void)
5015 sbitmap_vector_ones (transpout
, last_basic_block
);
5019 /* Note that flow inserted a nop a the end of basic blocks that
5020 end in call instructions for reasons other than abnormal
5022 if (! CALL_P (BB_END (bb
)))
5025 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5026 for (expr
= expr_hash_table
.table
[i
]; expr
; expr
= expr
->next_same_hash
)
5027 if (MEM_P (expr
->expr
))
5029 if (GET_CODE (XEXP (expr
->expr
, 0)) == SYMBOL_REF
5030 && CONSTANT_POOL_ADDRESS_P (XEXP (expr
->expr
, 0)))
5033 /* ??? Optimally, we would use interprocedural alias
5034 analysis to determine if this mem is actually killed
5036 RESET_BIT (transpout
[bb
->index
], expr
->bitmap_index
);
5041 /* Code Hoisting variables and subroutines. */
5043 /* Very busy expressions. */
5044 static sbitmap
*hoist_vbein
;
5045 static sbitmap
*hoist_vbeout
;
5047 /* Hoistable expressions. */
5048 static sbitmap
*hoist_exprs
;
5050 /* ??? We could compute post dominators and run this algorithm in
5051 reverse to perform tail merging, doing so would probably be
5052 more effective than the tail merging code in jump.c.
5054 It's unclear if tail merging could be run in parallel with
5055 code hoisting. It would be nice. */
5057 /* Allocate vars used for code hoisting analysis. */
5060 alloc_code_hoist_mem (int n_blocks
, int n_exprs
)
5062 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5063 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5064 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5066 hoist_vbein
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5067 hoist_vbeout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5068 hoist_exprs
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5069 transpout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
5072 /* Free vars used for code hoisting analysis. */
5075 free_code_hoist_mem (void)
5077 sbitmap_vector_free (antloc
);
5078 sbitmap_vector_free (transp
);
5079 sbitmap_vector_free (comp
);
5081 sbitmap_vector_free (hoist_vbein
);
5082 sbitmap_vector_free (hoist_vbeout
);
5083 sbitmap_vector_free (hoist_exprs
);
5084 sbitmap_vector_free (transpout
);
5086 free_dominance_info (CDI_DOMINATORS
);
5089 /* Compute the very busy expressions at entry/exit from each block.
5091 An expression is very busy if all paths from a given point
5092 compute the expression. */
5095 compute_code_hoist_vbeinout (void)
5097 int changed
, passes
;
5100 sbitmap_vector_zero (hoist_vbeout
, last_basic_block
);
5101 sbitmap_vector_zero (hoist_vbein
, last_basic_block
);
5110 /* We scan the blocks in the reverse order to speed up
5112 FOR_EACH_BB_REVERSE (bb
)
5114 changed
|= sbitmap_a_or_b_and_c_cg (hoist_vbein
[bb
->index
], antloc
[bb
->index
],
5115 hoist_vbeout
[bb
->index
], transp
[bb
->index
]);
5116 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
5117 sbitmap_intersection_of_succs (hoist_vbeout
[bb
->index
], hoist_vbein
, bb
->index
);
5124 fprintf (gcse_file
, "hoisting vbeinout computation: %d passes\n", passes
);
5127 /* Top level routine to do the dataflow analysis needed by code hoisting. */
5130 compute_code_hoist_data (void)
5132 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
5133 compute_transpout ();
5134 compute_code_hoist_vbeinout ();
5135 calculate_dominance_info (CDI_DOMINATORS
);
5137 fprintf (gcse_file
, "\n");
5140 /* Determine if the expression identified by EXPR_INDEX would
5141 reach BB unimpared if it was placed at the end of EXPR_BB.
5143 It's unclear exactly what Muchnick meant by "unimpared". It seems
5144 to me that the expression must either be computed or transparent in
5145 *every* block in the path(s) from EXPR_BB to BB. Any other definition
5146 would allow the expression to be hoisted out of loops, even if
5147 the expression wasn't a loop invariant.
5149 Contrast this to reachability for PRE where an expression is
5150 considered reachable if *any* path reaches instead of *all*
5154 hoist_expr_reaches_here_p (basic_block expr_bb
, int expr_index
, basic_block bb
, char *visited
)
5157 int visited_allocated_locally
= 0;
5159 if (visited
== NULL
)
5161 visited_allocated_locally
= 1;
5162 visited
= xcalloc (last_basic_block
, 1);
5165 FOR_EACH_EDGE (pred
, bb
->preds
)
5167 basic_block pred_bb
= pred
->src
;
5169 if (pred
->src
== ENTRY_BLOCK_PTR
)
5171 else if (pred_bb
== expr_bb
)
5173 else if (visited
[pred_bb
->index
])
5176 /* Does this predecessor generate this expression? */
5177 else if (TEST_BIT (comp
[pred_bb
->index
], expr_index
))
5179 else if (! TEST_BIT (transp
[pred_bb
->index
], expr_index
))
5185 visited
[pred_bb
->index
] = 1;
5186 if (! hoist_expr_reaches_here_p (expr_bb
, expr_index
,
5192 if (visited_allocated_locally
)
5195 return (pred
== NULL
);
5198 /* Actually perform code hoisting. */
5203 basic_block bb
, dominated
;
5205 unsigned int domby_len
;
5207 struct expr
**index_map
;
5210 sbitmap_vector_zero (hoist_exprs
, last_basic_block
);
5212 /* Compute a mapping from expression number (`bitmap_index') to
5213 hash table entry. */
5215 index_map
= xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
5216 for (i
= 0; i
< expr_hash_table
.size
; i
++)
5217 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
5218 index_map
[expr
->bitmap_index
] = expr
;
5220 /* Walk over each basic block looking for potentially hoistable
5221 expressions, nothing gets hoisted from the entry block. */
5225 int insn_inserted_p
;
5227 domby_len
= get_dominated_by (CDI_DOMINATORS
, bb
, &domby
);
5228 /* Examine each expression that is very busy at the exit of this
5229 block. These are the potentially hoistable expressions. */
5230 for (i
= 0; i
< hoist_vbeout
[bb
->index
]->n_bits
; i
++)
5234 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
)
5235 && TEST_BIT (transpout
[bb
->index
], i
))
5237 /* We've found a potentially hoistable expression, now
5238 we look at every block BB dominates to see if it
5239 computes the expression. */
5240 for (j
= 0; j
< domby_len
; j
++)
5242 dominated
= domby
[j
];
5243 /* Ignore self dominance. */
5244 if (bb
== dominated
)
5246 /* We've found a dominated block, now see if it computes
5247 the busy expression and whether or not moving that
5248 expression to the "beginning" of that block is safe. */
5249 if (!TEST_BIT (antloc
[dominated
->index
], i
))
5252 /* Note if the expression would reach the dominated block
5253 unimpared if it was placed at the end of BB.
5255 Keep track of how many times this expression is hoistable
5256 from a dominated block into BB. */
5257 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
5261 /* If we found more than one hoistable occurrence of this
5262 expression, then note it in the bitmap of expressions to
5263 hoist. It makes no sense to hoist things which are computed
5264 in only one BB, and doing so tends to pessimize register
5265 allocation. One could increase this value to try harder
5266 to avoid any possible code expansion due to register
5267 allocation issues; however experiments have shown that
5268 the vast majority of hoistable expressions are only movable
5269 from two successors, so raising this threshold is likely
5270 to nullify any benefit we get from code hoisting. */
5273 SET_BIT (hoist_exprs
[bb
->index
], i
);
5278 /* If we found nothing to hoist, then quit now. */
5285 /* Loop over all the hoistable expressions. */
5286 for (i
= 0; i
< hoist_exprs
[bb
->index
]->n_bits
; i
++)
5288 /* We want to insert the expression into BB only once, so
5289 note when we've inserted it. */
5290 insn_inserted_p
= 0;
5292 /* These tests should be the same as the tests above. */
5293 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
))
5295 /* We've found a potentially hoistable expression, now
5296 we look at every block BB dominates to see if it
5297 computes the expression. */
5298 for (j
= 0; j
< domby_len
; j
++)
5300 dominated
= domby
[j
];
5301 /* Ignore self dominance. */
5302 if (bb
== dominated
)
5305 /* We've found a dominated block, now see if it computes
5306 the busy expression and whether or not moving that
5307 expression to the "beginning" of that block is safe. */
5308 if (!TEST_BIT (antloc
[dominated
->index
], i
))
5311 /* The expression is computed in the dominated block and
5312 it would be safe to compute it at the start of the
5313 dominated block. Now we have to determine if the
5314 expression would reach the dominated block if it was
5315 placed at the end of BB. */
5316 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
5318 struct expr
*expr
= index_map
[i
];
5319 struct occr
*occr
= expr
->antic_occr
;
5323 /* Find the right occurrence of this expression. */
5324 while (BLOCK_FOR_INSN (occr
->insn
) != dominated
&& occr
)
5327 /* Should never happen. */
5333 set
= single_set (insn
);
5337 /* Create a pseudo-reg to store the result of reaching
5338 expressions into. Get the mode for the new pseudo
5339 from the mode of the original destination pseudo. */
5340 if (expr
->reaching_reg
== NULL
)
5342 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
5344 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
5346 occr
->deleted_p
= 1;
5347 if (!insn_inserted_p
)
5349 insert_insn_end_bb (index_map
[i
], bb
, 0);
5350 insn_inserted_p
= 1;
5362 /* Top level routine to perform one code hoisting (aka unification) pass
5364 Return nonzero if a change was made. */
5367 one_code_hoisting_pass (void)
5371 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
5372 compute_hash_table (&expr_hash_table
);
5374 dump_hash_table (gcse_file
, "Code Hosting Expressions", &expr_hash_table
);
5376 if (expr_hash_table
.n_elems
> 0)
5378 alloc_code_hoist_mem (last_basic_block
, expr_hash_table
.n_elems
);
5379 compute_code_hoist_data ();
5381 free_code_hoist_mem ();
5384 free_hash_table (&expr_hash_table
);
5389 /* Here we provide the things required to do store motion towards
5390 the exit. In order for this to be effective, gcse also needed to
5391 be taught how to move a load when it is kill only by a store to itself.
5396 void foo(float scale)
5398 for (i=0; i<10; i++)
5402 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
5403 the load out since its live around the loop, and stored at the bottom
5406 The 'Load Motion' referred to and implemented in this file is
5407 an enhancement to gcse which when using edge based lcm, recognizes
5408 this situation and allows gcse to move the load out of the loop.
5410 Once gcse has hoisted the load, store motion can then push this
5411 load towards the exit, and we end up with no loads or stores of 'i'
5414 /* This will search the ldst list for a matching expression. If it
5415 doesn't find one, we create one and initialize it. */
5417 static struct ls_expr
*
5420 int do_not_record_p
= 0;
5421 struct ls_expr
* ptr
;
5424 hash
= hash_expr_1 (x
, GET_MODE (x
), & do_not_record_p
);
5426 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
5427 if (ptr
->hash_index
== hash
&& expr_equiv_p (ptr
->pattern
, x
))
5430 ptr
= xmalloc (sizeof (struct ls_expr
));
5432 ptr
->next
= pre_ldst_mems
;
5435 ptr
->pattern_regs
= NULL_RTX
;
5436 ptr
->loads
= NULL_RTX
;
5437 ptr
->stores
= NULL_RTX
;
5438 ptr
->reaching_reg
= NULL_RTX
;
5441 ptr
->hash_index
= hash
;
5442 pre_ldst_mems
= ptr
;
5447 /* Free up an individual ldst entry. */
5450 free_ldst_entry (struct ls_expr
* ptr
)
5452 free_INSN_LIST_list (& ptr
->loads
);
5453 free_INSN_LIST_list (& ptr
->stores
);
5458 /* Free up all memory associated with the ldst list. */
5461 free_ldst_mems (void)
5463 while (pre_ldst_mems
)
5465 struct ls_expr
* tmp
= pre_ldst_mems
;
5467 pre_ldst_mems
= pre_ldst_mems
->next
;
5469 free_ldst_entry (tmp
);
5472 pre_ldst_mems
= NULL
;
5475 /* Dump debugging info about the ldst list. */
5478 print_ldst_list (FILE * file
)
5480 struct ls_expr
* ptr
;
5482 fprintf (file
, "LDST list: \n");
5484 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
5486 fprintf (file
, " Pattern (%3d): ", ptr
->index
);
5488 print_rtl (file
, ptr
->pattern
);
5490 fprintf (file
, "\n Loads : ");
5493 print_rtl (file
, ptr
->loads
);
5495 fprintf (file
, "(nil)");
5497 fprintf (file
, "\n Stores : ");
5500 print_rtl (file
, ptr
->stores
);
5502 fprintf (file
, "(nil)");
5504 fprintf (file
, "\n\n");
5507 fprintf (file
, "\n");
5510 /* Returns 1 if X is in the list of ldst only expressions. */
5512 static struct ls_expr
*
5513 find_rtx_in_ldst (rtx x
)
5515 struct ls_expr
* ptr
;
5517 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
5518 if (expr_equiv_p (ptr
->pattern
, x
) && ! ptr
->invalid
)
5524 /* Assign each element of the list of mems a monotonically increasing value. */
5527 enumerate_ldsts (void)
5529 struct ls_expr
* ptr
;
5532 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
5538 /* Return first item in the list. */
5540 static inline struct ls_expr
*
5541 first_ls_expr (void)
5543 return pre_ldst_mems
;
5546 /* Return the next item in the list after the specified one. */
5548 static inline struct ls_expr
*
5549 next_ls_expr (struct ls_expr
* ptr
)
5554 /* Load Motion for loads which only kill themselves. */
5556 /* Return true if x is a simple MEM operation, with no registers or
5557 side effects. These are the types of loads we consider for the
5558 ld_motion list, otherwise we let the usual aliasing take care of it. */
5566 if (MEM_VOLATILE_P (x
))
5569 if (GET_MODE (x
) == BLKmode
)
5572 /* If we are handling exceptions, we must be careful with memory references
5573 that may trap. If we are not, the behavior is undefined, so we may just
5575 if (flag_non_call_exceptions
&& may_trap_p (x
))
5578 if (side_effects_p (x
))
5581 /* Do not consider function arguments passed on stack. */
5582 if (reg_mentioned_p (stack_pointer_rtx
, x
))
5585 if (flag_float_store
&& FLOAT_MODE_P (GET_MODE (x
)))
5591 /* Make sure there isn't a buried reference in this pattern anywhere.
5592 If there is, invalidate the entry for it since we're not capable
5593 of fixing it up just yet.. We have to be sure we know about ALL
5594 loads since the aliasing code will allow all entries in the
5595 ld_motion list to not-alias itself. If we miss a load, we will get
5596 the wrong value since gcse might common it and we won't know to
5600 invalidate_any_buried_refs (rtx x
)
5604 struct ls_expr
* ptr
;
5606 /* Invalidate it in the list. */
5607 if (MEM_P (x
) && simple_mem (x
))
5609 ptr
= ldst_entry (x
);
5613 /* Recursively process the insn. */
5614 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
5616 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0; i
--)
5619 invalidate_any_buried_refs (XEXP (x
, i
));
5620 else if (fmt
[i
] == 'E')
5621 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5622 invalidate_any_buried_refs (XVECEXP (x
, i
, j
));
5626 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
5627 being defined as MEM loads and stores to symbols, with no side effects
5628 and no registers in the expression. For a MEM destination, we also
5629 check that the insn is still valid if we replace the destination with a
5630 REG, as is done in update_ld_motion_stores. If there are any uses/defs
5631 which don't match this criteria, they are invalidated and trimmed out
5635 compute_ld_motion_mems (void)
5637 struct ls_expr
* ptr
;
5641 pre_ldst_mems
= NULL
;
5645 for (insn
= BB_HEAD (bb
);
5646 insn
&& insn
!= NEXT_INSN (BB_END (bb
));
5647 insn
= NEXT_INSN (insn
))
5651 if (GET_CODE (PATTERN (insn
)) == SET
)
5653 rtx src
= SET_SRC (PATTERN (insn
));
5654 rtx dest
= SET_DEST (PATTERN (insn
));
5656 /* Check for a simple LOAD... */
5657 if (MEM_P (src
) && simple_mem (src
))
5659 ptr
= ldst_entry (src
);
5661 ptr
->loads
= alloc_INSN_LIST (insn
, ptr
->loads
);
5667 /* Make sure there isn't a buried load somewhere. */
5668 invalidate_any_buried_refs (src
);
5671 /* Check for stores. Don't worry about aliased ones, they
5672 will block any movement we might do later. We only care
5673 about this exact pattern since those are the only
5674 circumstance that we will ignore the aliasing info. */
5675 if (MEM_P (dest
) && simple_mem (dest
))
5677 ptr
= ldst_entry (dest
);
5680 && GET_CODE (src
) != ASM_OPERANDS
5681 /* Check for REG manually since want_to_gcse_p
5682 returns 0 for all REGs. */
5683 && can_assign_to_reg_p (src
))
5684 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
5690 invalidate_any_buried_refs (PATTERN (insn
));
5696 /* Remove any references that have been either invalidated or are not in the
5697 expression list for pre gcse. */
5700 trim_ld_motion_mems (void)
5702 struct ls_expr
* * last
= & pre_ldst_mems
;
5703 struct ls_expr
* ptr
= pre_ldst_mems
;
5709 /* Delete if entry has been made invalid. */
5712 /* Delete if we cannot find this mem in the expression list. */
5713 unsigned int hash
= ptr
->hash_index
% expr_hash_table
.size
;
5715 for (expr
= expr_hash_table
.table
[hash
];
5717 expr
= expr
->next_same_hash
)
5718 if (expr_equiv_p (expr
->expr
, ptr
->pattern
))
5722 expr
= (struct expr
*) 0;
5726 /* Set the expression field if we are keeping it. */
5734 free_ldst_entry (ptr
);
5739 /* Show the world what we've found. */
5740 if (gcse_file
&& pre_ldst_mems
!= NULL
)
5741 print_ldst_list (gcse_file
);
5744 /* This routine will take an expression which we are replacing with
5745 a reaching register, and update any stores that are needed if
5746 that expression is in the ld_motion list. Stores are updated by
5747 copying their SRC to the reaching register, and then storing
5748 the reaching register into the store location. These keeps the
5749 correct value in the reaching register for the loads. */
5752 update_ld_motion_stores (struct expr
* expr
)
5754 struct ls_expr
* mem_ptr
;
5756 if ((mem_ptr
= find_rtx_in_ldst (expr
->expr
)))
5758 /* We can try to find just the REACHED stores, but is shouldn't
5759 matter to set the reaching reg everywhere... some might be
5760 dead and should be eliminated later. */
5762 /* We replace (set mem expr) with (set reg expr) (set mem reg)
5763 where reg is the reaching reg used in the load. We checked in
5764 compute_ld_motion_mems that we can replace (set mem expr) with
5765 (set reg expr) in that insn. */
5766 rtx list
= mem_ptr
->stores
;
5768 for ( ; list
!= NULL_RTX
; list
= XEXP (list
, 1))
5770 rtx insn
= XEXP (list
, 0);
5771 rtx pat
= PATTERN (insn
);
5772 rtx src
= SET_SRC (pat
);
5773 rtx reg
= expr
->reaching_reg
;
5776 /* If we've already copied it, continue. */
5777 if (expr
->reaching_reg
== src
)
5782 fprintf (gcse_file
, "PRE: store updated with reaching reg ");
5783 print_rtl (gcse_file
, expr
->reaching_reg
);
5784 fprintf (gcse_file
, ":\n ");
5785 print_inline_rtx (gcse_file
, insn
, 8);
5786 fprintf (gcse_file
, "\n");
5789 copy
= gen_move_insn ( reg
, copy_rtx (SET_SRC (pat
)));
5790 new = emit_insn_before (copy
, insn
);
5791 record_one_set (REGNO (reg
), new);
5792 SET_SRC (pat
) = reg
;
5794 /* un-recognize this pattern since it's probably different now. */
5795 INSN_CODE (insn
) = -1;
5796 gcse_create_count
++;
5801 /* Store motion code. */
5803 #define ANTIC_STORE_LIST(x) ((x)->loads)
5804 #define AVAIL_STORE_LIST(x) ((x)->stores)
5805 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
5807 /* This is used to communicate the target bitvector we want to use in the
5808 reg_set_info routine when called via the note_stores mechanism. */
5809 static int * regvec
;
5811 /* And current insn, for the same routine. */
5812 static rtx compute_store_table_current_insn
;
5814 /* Used in computing the reverse edge graph bit vectors. */
5815 static sbitmap
* st_antloc
;
5817 /* Global holding the number of store expressions we are dealing with. */
5818 static int num_stores
;
5820 /* Checks to set if we need to mark a register set. Called from
5824 reg_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
,
5827 sbitmap bb_reg
= data
;
5829 if (GET_CODE (dest
) == SUBREG
)
5830 dest
= SUBREG_REG (dest
);
5834 regvec
[REGNO (dest
)] = INSN_UID (compute_store_table_current_insn
);
5836 SET_BIT (bb_reg
, REGNO (dest
));
5840 /* Clear any mark that says that this insn sets dest. Called from
5844 reg_clear_last_set (rtx dest
, rtx setter ATTRIBUTE_UNUSED
,
5847 int *dead_vec
= data
;
5849 if (GET_CODE (dest
) == SUBREG
)
5850 dest
= SUBREG_REG (dest
);
5853 dead_vec
[REGNO (dest
)] == INSN_UID (compute_store_table_current_insn
))
5854 dead_vec
[REGNO (dest
)] = 0;
5857 /* Return zero if some of the registers in list X are killed
5858 due to set of registers in bitmap REGS_SET. */
5861 store_ops_ok (rtx x
, int *regs_set
)
5865 for (; x
; x
= XEXP (x
, 1))
5868 if (regs_set
[REGNO(reg
)])
5875 /* Returns a list of registers mentioned in X. */
5877 extract_mentioned_regs (rtx x
)
5879 return extract_mentioned_regs_helper (x
, NULL_RTX
);
5882 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
5885 extract_mentioned_regs_helper (rtx x
, rtx accum
)
5891 /* Repeat is used to turn tail-recursion into iteration. */
5897 code
= GET_CODE (x
);
5901 return alloc_EXPR_LIST (0, x
, accum
);
5911 /* We do not run this function with arguments having side effects. */
5930 i
= GET_RTX_LENGTH (code
) - 1;
5931 fmt
= GET_RTX_FORMAT (code
);
5937 rtx tem
= XEXP (x
, i
);
5939 /* If we are about to do the last recursive call
5940 needed at this level, change it into iteration. */
5947 accum
= extract_mentioned_regs_helper (tem
, accum
);
5949 else if (fmt
[i
] == 'E')
5953 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
5954 accum
= extract_mentioned_regs_helper (XVECEXP (x
, i
, j
), accum
);
5961 /* Determine whether INSN is MEM store pattern that we will consider moving.
5962 REGS_SET_BEFORE is bitmap of registers set before (and including) the
5963 current insn, REGS_SET_AFTER is bitmap of registers set after (and
5964 including) the insn in this basic block. We must be passing through BB from
5965 head to end, as we are using this fact to speed things up.
5967 The results are stored this way:
5969 -- the first anticipatable expression is added into ANTIC_STORE_LIST
5970 -- if the processed expression is not anticipatable, NULL_RTX is added
5971 there instead, so that we can use it as indicator that no further
5972 expression of this type may be anticipatable
5973 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
5974 consequently, all of them but this head are dead and may be deleted.
5975 -- if the expression is not available, the insn due to that it fails to be
5976 available is stored in reaching_reg.
5978 The things are complicated a bit by fact that there already may be stores
5979 to the same MEM from other blocks; also caller must take care of the
5980 necessary cleanup of the temporary markers after end of the basic block.
5984 find_moveable_store (rtx insn
, int *regs_set_before
, int *regs_set_after
)
5986 struct ls_expr
* ptr
;
5988 int check_anticipatable
, check_available
;
5989 basic_block bb
= BLOCK_FOR_INSN (insn
);
5991 set
= single_set (insn
);
5995 dest
= SET_DEST (set
);
5997 if (! MEM_P (dest
) || MEM_VOLATILE_P (dest
)
5998 || GET_MODE (dest
) == BLKmode
)
6001 if (side_effects_p (dest
))
6004 /* If we are handling exceptions, we must be careful with memory references
6005 that may trap. If we are not, the behavior is undefined, so we may just
6007 if (flag_non_call_exceptions
&& may_trap_p (dest
))
6010 /* Even if the destination cannot trap, the source may. In this case we'd
6011 need to handle updating the REG_EH_REGION note. */
6012 if (find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
))
6015 ptr
= ldst_entry (dest
);
6016 if (!ptr
->pattern_regs
)
6017 ptr
->pattern_regs
= extract_mentioned_regs (dest
);
6019 /* Do not check for anticipatability if we either found one anticipatable
6020 store already, or tested for one and found out that it was killed. */
6021 check_anticipatable
= 0;
6022 if (!ANTIC_STORE_LIST (ptr
))
6023 check_anticipatable
= 1;
6026 tmp
= XEXP (ANTIC_STORE_LIST (ptr
), 0);
6028 && BLOCK_FOR_INSN (tmp
) != bb
)
6029 check_anticipatable
= 1;
6031 if (check_anticipatable
)
6033 if (store_killed_before (dest
, ptr
->pattern_regs
, insn
, bb
, regs_set_before
))
6037 ANTIC_STORE_LIST (ptr
) = alloc_INSN_LIST (tmp
,
6038 ANTIC_STORE_LIST (ptr
));
6041 /* It is not necessary to check whether store is available if we did
6042 it successfully before; if we failed before, do not bother to check
6043 until we reach the insn that caused us to fail. */
6044 check_available
= 0;
6045 if (!AVAIL_STORE_LIST (ptr
))
6046 check_available
= 1;
6049 tmp
= XEXP (AVAIL_STORE_LIST (ptr
), 0);
6050 if (BLOCK_FOR_INSN (tmp
) != bb
)
6051 check_available
= 1;
6053 if (check_available
)
6055 /* Check that we have already reached the insn at that the check
6056 failed last time. */
6057 if (LAST_AVAIL_CHECK_FAILURE (ptr
))
6059 for (tmp
= BB_END (bb
);
6060 tmp
!= insn
&& tmp
!= LAST_AVAIL_CHECK_FAILURE (ptr
);
6061 tmp
= PREV_INSN (tmp
))
6064 check_available
= 0;
6067 check_available
= store_killed_after (dest
, ptr
->pattern_regs
, insn
,
6069 &LAST_AVAIL_CHECK_FAILURE (ptr
));
6071 if (!check_available
)
6072 AVAIL_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
, AVAIL_STORE_LIST (ptr
));
6075 /* Find available and anticipatable stores. */
6078 compute_store_table (void)
6084 int *last_set_in
, *already_set
;
6085 struct ls_expr
* ptr
, **prev_next_ptr_ptr
;
6087 max_gcse_regno
= max_reg_num ();
6089 reg_set_in_block
= sbitmap_vector_alloc (last_basic_block
,
6091 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
6093 last_set_in
= xcalloc (max_gcse_regno
, sizeof (int));
6094 already_set
= xmalloc (sizeof (int) * max_gcse_regno
);
6096 /* Find all the stores we care about. */
6099 /* First compute the registers set in this block. */
6100 regvec
= last_set_in
;
6102 for (insn
= BB_HEAD (bb
);
6103 insn
!= NEXT_INSN (BB_END (bb
));
6104 insn
= NEXT_INSN (insn
))
6106 if (! INSN_P (insn
))
6111 bool clobbers_all
= false;
6112 #ifdef NON_SAVING_SETJMP
6113 if (NON_SAVING_SETJMP
6114 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
6115 clobbers_all
= true;
6118 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
6120 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
6122 last_set_in
[regno
] = INSN_UID (insn
);
6123 SET_BIT (reg_set_in_block
[bb
->index
], regno
);
6127 pat
= PATTERN (insn
);
6128 compute_store_table_current_insn
= insn
;
6129 note_stores (pat
, reg_set_info
, reg_set_in_block
[bb
->index
]);
6132 /* Now find the stores. */
6133 memset (already_set
, 0, sizeof (int) * max_gcse_regno
);
6134 regvec
= already_set
;
6135 for (insn
= BB_HEAD (bb
);
6136 insn
!= NEXT_INSN (BB_END (bb
));
6137 insn
= NEXT_INSN (insn
))
6139 if (! INSN_P (insn
))
6144 bool clobbers_all
= false;
6145 #ifdef NON_SAVING_SETJMP
6146 if (NON_SAVING_SETJMP
6147 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
6148 clobbers_all
= true;
6151 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
6153 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
6154 already_set
[regno
] = 1;
6157 pat
= PATTERN (insn
);
6158 note_stores (pat
, reg_set_info
, NULL
);
6160 /* Now that we've marked regs, look for stores. */
6161 find_moveable_store (insn
, already_set
, last_set_in
);
6163 /* Unmark regs that are no longer set. */
6164 compute_store_table_current_insn
= insn
;
6165 note_stores (pat
, reg_clear_last_set
, last_set_in
);
6168 bool clobbers_all
= false;
6169 #ifdef NON_SAVING_SETJMP
6170 if (NON_SAVING_SETJMP
6171 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
6172 clobbers_all
= true;
6175 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
6177 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
6178 && last_set_in
[regno
] == INSN_UID (insn
))
6179 last_set_in
[regno
] = 0;
6183 #ifdef ENABLE_CHECKING
6184 /* last_set_in should now be all-zero. */
6185 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
6186 if (last_set_in
[regno
] != 0)
6190 /* Clear temporary marks. */
6191 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6193 LAST_AVAIL_CHECK_FAILURE(ptr
) = NULL_RTX
;
6194 if (ANTIC_STORE_LIST (ptr
)
6195 && (tmp
= XEXP (ANTIC_STORE_LIST (ptr
), 0)) == NULL_RTX
)
6196 ANTIC_STORE_LIST (ptr
) = XEXP (ANTIC_STORE_LIST (ptr
), 1);
6200 /* Remove the stores that are not available anywhere, as there will
6201 be no opportunity to optimize them. */
6202 for (ptr
= pre_ldst_mems
, prev_next_ptr_ptr
= &pre_ldst_mems
;
6204 ptr
= *prev_next_ptr_ptr
)
6206 if (!AVAIL_STORE_LIST (ptr
))
6208 *prev_next_ptr_ptr
= ptr
->next
;
6209 free_ldst_entry (ptr
);
6212 prev_next_ptr_ptr
= &ptr
->next
;
6215 ret
= enumerate_ldsts ();
6219 fprintf (gcse_file
, "ST_avail and ST_antic (shown under loads..)\n");
6220 print_ldst_list (gcse_file
);
6228 /* Check to see if the load X is aliased with STORE_PATTERN.
6229 AFTER is true if we are checking the case when STORE_PATTERN occurs
6233 load_kills_store (rtx x
, rtx store_pattern
, int after
)
6236 return anti_dependence (x
, store_pattern
);
6238 return true_dependence (store_pattern
, GET_MODE (store_pattern
), x
,
6242 /* Go through the entire insn X, looking for any loads which might alias
6243 STORE_PATTERN. Return true if found.
6244 AFTER is true if we are checking the case when STORE_PATTERN occurs
6245 after the insn X. */
6248 find_loads (rtx x
, rtx store_pattern
, int after
)
6257 if (GET_CODE (x
) == SET
)
6262 if (load_kills_store (x
, store_pattern
, after
))
6266 /* Recursively process the insn. */
6267 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
6269 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0 && !ret
; i
--)
6272 ret
|= find_loads (XEXP (x
, i
), store_pattern
, after
);
6273 else if (fmt
[i
] == 'E')
6274 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
6275 ret
|= find_loads (XVECEXP (x
, i
, j
), store_pattern
, after
);
6280 /* Check if INSN kills the store pattern X (is aliased with it).
6281 AFTER is true if we are checking the case when store X occurs
6282 after the insn. Return true if it it does. */
6285 store_killed_in_insn (rtx x
, rtx x_regs
, rtx insn
, int after
)
6287 rtx reg
, base
, note
;
6294 /* A normal or pure call might read from pattern,
6295 but a const call will not. */
6296 if (! CONST_OR_PURE_CALL_P (insn
) || pure_call_p (insn
))
6299 /* But even a const call reads its parameters. Check whether the
6300 base of some of registers used in mem is stack pointer. */
6301 for (reg
= x_regs
; reg
; reg
= XEXP (reg
, 1))
6303 base
= find_base_term (XEXP (reg
, 0));
6305 || (GET_CODE (base
) == ADDRESS
6306 && GET_MODE (base
) == Pmode
6307 && XEXP (base
, 0) == stack_pointer_rtx
))
6314 if (GET_CODE (PATTERN (insn
)) == SET
)
6316 rtx pat
= PATTERN (insn
);
6317 rtx dest
= SET_DEST (pat
);
6319 if (GET_CODE (dest
) == SIGN_EXTRACT
6320 || GET_CODE (dest
) == ZERO_EXTRACT
)
6321 dest
= XEXP (dest
, 0);
6323 /* Check for memory stores to aliased objects. */
6325 && !expr_equiv_p (dest
, x
))
6329 if (output_dependence (dest
, x
))
6334 if (output_dependence (x
, dest
))
6338 if (find_loads (SET_SRC (pat
), x
, after
))
6341 else if (find_loads (PATTERN (insn
), x
, after
))
6344 /* If this insn has a REG_EQUAL or REG_EQUIV note referencing a memory
6345 location aliased with X, then this insn kills X. */
6346 note
= find_reg_equal_equiv_note (insn
);
6349 note
= XEXP (note
, 0);
6351 /* However, if the note represents a must alias rather than a may
6352 alias relationship, then it does not kill X. */
6353 if (expr_equiv_p (note
, x
))
6356 /* See if there are any aliased loads in the note. */
6357 return find_loads (note
, x
, after
);
6360 /* Returns true if the expression X is loaded or clobbered on or after INSN
6361 within basic block BB. REGS_SET_AFTER is bitmap of registers set in
6362 or after the insn. X_REGS is list of registers mentioned in X. If the store
6363 is killed, return the last insn in that it occurs in FAIL_INSN. */
6366 store_killed_after (rtx x
, rtx x_regs
, rtx insn
, basic_block bb
,
6367 int *regs_set_after
, rtx
*fail_insn
)
6369 rtx last
= BB_END (bb
), act
;
6371 if (!store_ops_ok (x_regs
, regs_set_after
))
6373 /* We do not know where it will happen. */
6375 *fail_insn
= NULL_RTX
;
6379 /* Scan from the end, so that fail_insn is determined correctly. */
6380 for (act
= last
; act
!= PREV_INSN (insn
); act
= PREV_INSN (act
))
6381 if (store_killed_in_insn (x
, x_regs
, act
, false))
6391 /* Returns true if the expression X is loaded or clobbered on or before INSN
6392 within basic block BB. X_REGS is list of registers mentioned in X.
6393 REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
6395 store_killed_before (rtx x
, rtx x_regs
, rtx insn
, basic_block bb
,
6396 int *regs_set_before
)
6398 rtx first
= BB_HEAD (bb
);
6400 if (!store_ops_ok (x_regs
, regs_set_before
))
6403 for ( ; insn
!= PREV_INSN (first
); insn
= PREV_INSN (insn
))
6404 if (store_killed_in_insn (x
, x_regs
, insn
, true))
6410 /* Fill in available, anticipatable, transparent and kill vectors in
6411 STORE_DATA, based on lists of available and anticipatable stores. */
6413 build_store_vectors (void)
6416 int *regs_set_in_block
;
6418 struct ls_expr
* ptr
;
6421 /* Build the gen_vector. This is any store in the table which is not killed
6422 by aliasing later in its block. */
6423 ae_gen
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6424 sbitmap_vector_zero (ae_gen
, last_basic_block
);
6426 st_antloc
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6427 sbitmap_vector_zero (st_antloc
, last_basic_block
);
6429 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6431 for (st
= AVAIL_STORE_LIST (ptr
); st
!= NULL
; st
= XEXP (st
, 1))
6433 insn
= XEXP (st
, 0);
6434 bb
= BLOCK_FOR_INSN (insn
);
6436 /* If we've already seen an available expression in this block,
6437 we can delete this one (It occurs earlier in the block). We'll
6438 copy the SRC expression to an unused register in case there
6439 are any side effects. */
6440 if (TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
6442 rtx r
= gen_reg_rtx (GET_MODE (ptr
->pattern
));
6444 fprintf (gcse_file
, "Removing redundant store:\n");
6445 replace_store_insn (r
, XEXP (st
, 0), bb
, ptr
);
6448 SET_BIT (ae_gen
[bb
->index
], ptr
->index
);
6451 for (st
= ANTIC_STORE_LIST (ptr
); st
!= NULL
; st
= XEXP (st
, 1))
6453 insn
= XEXP (st
, 0);
6454 bb
= BLOCK_FOR_INSN (insn
);
6455 SET_BIT (st_antloc
[bb
->index
], ptr
->index
);
6459 ae_kill
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6460 sbitmap_vector_zero (ae_kill
, last_basic_block
);
6462 transp
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6463 sbitmap_vector_zero (transp
, last_basic_block
);
6464 regs_set_in_block
= xmalloc (sizeof (int) * max_gcse_regno
);
6468 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
6469 regs_set_in_block
[regno
] = TEST_BIT (reg_set_in_block
[bb
->index
], regno
);
6471 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6473 if (store_killed_after (ptr
->pattern
, ptr
->pattern_regs
, BB_HEAD (bb
),
6474 bb
, regs_set_in_block
, NULL
))
6476 /* It should not be necessary to consider the expression
6477 killed if it is both anticipatable and available. */
6478 if (!TEST_BIT (st_antloc
[bb
->index
], ptr
->index
)
6479 || !TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
6480 SET_BIT (ae_kill
[bb
->index
], ptr
->index
);
6483 SET_BIT (transp
[bb
->index
], ptr
->index
);
6487 free (regs_set_in_block
);
6491 dump_sbitmap_vector (gcse_file
, "st_antloc", "", st_antloc
, last_basic_block
);
6492 dump_sbitmap_vector (gcse_file
, "st_kill", "", ae_kill
, last_basic_block
);
6493 dump_sbitmap_vector (gcse_file
, "Transpt", "", transp
, last_basic_block
);
6494 dump_sbitmap_vector (gcse_file
, "st_avloc", "", ae_gen
, last_basic_block
);
6498 /* Insert an instruction at the beginning of a basic block, and update
6499 the BB_HEAD if needed. */
6502 insert_insn_start_bb (rtx insn
, basic_block bb
)
6504 /* Insert at start of successor block. */
6505 rtx prev
= PREV_INSN (BB_HEAD (bb
));
6506 rtx before
= BB_HEAD (bb
);
6509 if (! LABEL_P (before
)
6510 && (! NOTE_P (before
)
6511 || NOTE_LINE_NUMBER (before
) != NOTE_INSN_BASIC_BLOCK
))
6514 if (prev
== BB_END (bb
))
6516 before
= NEXT_INSN (before
);
6519 insn
= emit_insn_after (insn
, prev
);
6523 fprintf (gcse_file
, "STORE_MOTION insert store at start of BB %d:\n",
6525 print_inline_rtx (gcse_file
, insn
, 6);
6526 fprintf (gcse_file
, "\n");
6530 /* This routine will insert a store on an edge. EXPR is the ldst entry for
6531 the memory reference, and E is the edge to insert it on. Returns nonzero
6532 if an edge insertion was performed. */
6535 insert_store (struct ls_expr
* expr
, edge e
)
6541 /* We did all the deleted before this insert, so if we didn't delete a
6542 store, then we haven't set the reaching reg yet either. */
6543 if (expr
->reaching_reg
== NULL_RTX
)
6546 if (e
->flags
& EDGE_FAKE
)
6549 reg
= expr
->reaching_reg
;
6550 insn
= gen_move_insn (copy_rtx (expr
->pattern
), reg
);
6552 /* If we are inserting this expression on ALL predecessor edges of a BB,
6553 insert it at the start of the BB, and reset the insert bits on the other
6554 edges so we don't try to insert it on the other edges. */
6556 FOR_EACH_EDGE (tmp
, e
->dest
->preds
)
6558 if (!(tmp
->flags
& EDGE_FAKE
))
6560 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
6561 if (index
== EDGE_INDEX_NO_EDGE
)
6563 if (! TEST_BIT (pre_insert_map
[index
], expr
->index
))
6569 /* If tmp is NULL, we found an insertion on every edge, blank the
6570 insertion vector for these edges, and insert at the start of the BB. */
6571 if (!tmp
&& bb
!= EXIT_BLOCK_PTR
)
6573 FOR_EACH_EDGE (tmp
, e
->dest
->preds
)
6575 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
6576 RESET_BIT (pre_insert_map
[index
], expr
->index
);
6579 insert_insn_start_bb (insn
, bb
);
6583 /* We can't insert on this edge, so we'll insert at the head of the
6584 successors block. See Morgan, sec 10.5. */
6585 if ((e
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
6587 insert_insn_start_bb (insn
, bb
);
6591 insert_insn_on_edge (insn
, e
);
6595 fprintf (gcse_file
, "STORE_MOTION insert insn on edge (%d, %d):\n",
6596 e
->src
->index
, e
->dest
->index
);
6597 print_inline_rtx (gcse_file
, insn
, 6);
6598 fprintf (gcse_file
, "\n");
6604 /* Remove any REG_EQUAL or REG_EQUIV notes containing a reference to the
6605 memory location in SMEXPR set in basic block BB.
6607 This could be rather expensive. */
6610 remove_reachable_equiv_notes (basic_block bb
, struct ls_expr
*smexpr
)
6612 edge
*stack
= xmalloc (sizeof (edge
) * n_basic_blocks
), act
;
6613 sbitmap visited
= sbitmap_alloc (last_basic_block
);
6615 rtx last
, insn
, note
;
6616 rtx mem
= smexpr
->pattern
;
6619 sbitmap_zero (visited
);
6620 act
= (EDGE_COUNT (bb
->succs
) > 0) ? EDGE_SUCC (bb
, 0) : NULL
;
6629 sbitmap_free (visited
);
6632 act
= stack
[--stack_top
];
6636 if (bb
== EXIT_BLOCK_PTR
6637 || TEST_BIT (visited
, bb
->index
))
6640 act
= (ix
>= EDGE_COUNT (bb
->succs
)) ? NULL
: EDGE_SUCC (bb
, ix
);
6643 SET_BIT (visited
, bb
->index
);
6645 if (TEST_BIT (st_antloc
[bb
->index
], smexpr
->index
))
6647 for (last
= ANTIC_STORE_LIST (smexpr
);
6648 BLOCK_FOR_INSN (XEXP (last
, 0)) != bb
;
6649 last
= XEXP (last
, 1))
6651 last
= XEXP (last
, 0);
6654 last
= NEXT_INSN (BB_END (bb
));
6656 for (insn
= BB_HEAD (bb
); insn
!= last
; insn
= NEXT_INSN (insn
))
6659 note
= find_reg_equal_equiv_note (insn
);
6660 if (!note
|| !expr_equiv_p (XEXP (note
, 0), mem
))
6664 fprintf (gcse_file
, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6666 remove_note (insn
, note
);
6669 act
= (ix
>= EDGE_COUNT (bb
->succs
)) ? NULL
: EDGE_SUCC (bb
, ix
);
6670 if (EDGE_COUNT (bb
->succs
) > 0)
6673 stack
[stack_top
++] = act
;
6675 act
= EDGE_SUCC (bb
, 0);
6680 /* This routine will replace a store with a SET to a specified register. */
6683 replace_store_insn (rtx reg
, rtx del
, basic_block bb
, struct ls_expr
*smexpr
)
6685 rtx insn
, mem
, note
, set
, ptr
;
6687 mem
= smexpr
->pattern
;
6688 insn
= gen_move_insn (reg
, SET_SRC (single_set (del
)));
6689 insn
= emit_insn_after (insn
, del
);
6694 "STORE_MOTION delete insn in BB %d:\n ", bb
->index
);
6695 print_inline_rtx (gcse_file
, del
, 6);
6696 fprintf (gcse_file
, "\nSTORE MOTION replaced with insn:\n ");
6697 print_inline_rtx (gcse_file
, insn
, 6);
6698 fprintf (gcse_file
, "\n");
6701 for (ptr
= ANTIC_STORE_LIST (smexpr
); ptr
; ptr
= XEXP (ptr
, 1))
6702 if (XEXP (ptr
, 0) == del
)
6704 XEXP (ptr
, 0) = insn
;
6709 /* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
6710 they are no longer accurate provided that they are reached by this
6711 definition, so drop them. */
6712 for (; insn
!= NEXT_INSN (BB_END (bb
)); insn
= NEXT_INSN (insn
))
6715 set
= single_set (insn
);
6718 if (expr_equiv_p (SET_DEST (set
), mem
))
6720 note
= find_reg_equal_equiv_note (insn
);
6721 if (!note
|| !expr_equiv_p (XEXP (note
, 0), mem
))
6725 fprintf (gcse_file
, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6727 remove_note (insn
, note
);
6729 remove_reachable_equiv_notes (bb
, smexpr
);
6733 /* Delete a store, but copy the value that would have been stored into
6734 the reaching_reg for later storing. */
6737 delete_store (struct ls_expr
* expr
, basic_block bb
)
6741 if (expr
->reaching_reg
== NULL_RTX
)
6742 expr
->reaching_reg
= gen_reg_rtx (GET_MODE (expr
->pattern
));
6744 reg
= expr
->reaching_reg
;
6746 for (i
= AVAIL_STORE_LIST (expr
); i
; i
= XEXP (i
, 1))
6749 if (BLOCK_FOR_INSN (del
) == bb
)
6751 /* We know there is only one since we deleted redundant
6752 ones during the available computation. */
6753 replace_store_insn (reg
, del
, bb
, expr
);
6759 /* Free memory used by store motion. */
6762 free_store_memory (void)
6767 sbitmap_vector_free (ae_gen
);
6769 sbitmap_vector_free (ae_kill
);
6771 sbitmap_vector_free (transp
);
6773 sbitmap_vector_free (st_antloc
);
6775 sbitmap_vector_free (pre_insert_map
);
6777 sbitmap_vector_free (pre_delete_map
);
6778 if (reg_set_in_block
)
6779 sbitmap_vector_free (reg_set_in_block
);
6781 ae_gen
= ae_kill
= transp
= st_antloc
= NULL
;
6782 pre_insert_map
= pre_delete_map
= reg_set_in_block
= NULL
;
6785 /* Perform store motion. Much like gcse, except we move expressions the
6786 other way by looking at the flowgraph in reverse. */
6793 struct ls_expr
* ptr
;
6794 int update_flow
= 0;
6798 fprintf (gcse_file
, "before store motion\n");
6799 print_rtl (gcse_file
, get_insns ());
6802 init_alias_analysis ();
6804 /* Find all the available and anticipatable stores. */
6805 num_stores
= compute_store_table ();
6806 if (num_stores
== 0)
6808 sbitmap_vector_free (reg_set_in_block
);
6809 end_alias_analysis ();
6813 /* Now compute kill & transp vectors. */
6814 build_store_vectors ();
6815 add_noreturn_fake_exit_edges ();
6816 connect_infinite_loops_to_exit ();
6818 edge_list
= pre_edge_rev_lcm (gcse_file
, num_stores
, transp
, ae_gen
,
6819 st_antloc
, ae_kill
, &pre_insert_map
,
6822 /* Now we want to insert the new stores which are going to be needed. */
6823 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6826 if (TEST_BIT (pre_delete_map
[bb
->index
], ptr
->index
))
6827 delete_store (ptr
, bb
);
6829 for (x
= 0; x
< NUM_EDGES (edge_list
); x
++)
6830 if (TEST_BIT (pre_insert_map
[x
], ptr
->index
))
6831 update_flow
|= insert_store (ptr
, INDEX_EDGE (edge_list
, x
));
6835 commit_edge_insertions ();
6837 free_store_memory ();
6838 free_edge_list (edge_list
);
6839 remove_fake_exit_edges ();
6840 end_alias_analysis ();
6844 /* Entry point for jump bypassing optimization pass. */
6847 bypass_jumps (FILE *file
)
6851 /* We do not construct an accurate cfg in functions which call
6852 setjmp, so just punt to be safe. */
6853 if (current_function_calls_setjmp
)
6856 /* For calling dump_foo fns from gdb. */
6857 debug_stderr
= stderr
;
6860 /* Identify the basic block information for this function, including
6861 successors and predecessors. */
6862 max_gcse_regno
= max_reg_num ();
6865 dump_flow_info (file
);
6867 /* Return if there's nothing to do, or it is too expensive. */
6868 if (n_basic_blocks
<= 1 || is_too_expensive (_ ("jump bypassing disabled")))
6871 gcc_obstack_init (&gcse_obstack
);
6874 /* We need alias. */
6875 init_alias_analysis ();
6877 /* Record where pseudo-registers are set. This data is kept accurate
6878 during each pass. ??? We could also record hard-reg information here
6879 [since it's unchanging], however it is currently done during hash table
6882 It may be tempting to compute MEM set information here too, but MEM sets
6883 will be subject to code motion one day and thus we need to compute
6884 information about memory sets when we build the hash tables. */
6886 alloc_reg_set_mem (max_gcse_regno
);
6887 compute_sets (get_insns ());
6889 max_gcse_regno
= max_reg_num ();
6890 alloc_gcse_mem (get_insns ());
6891 changed
= one_cprop_pass (1, 1, 1);
6896 fprintf (file
, "BYPASS of %s: %d basic blocks, ",
6897 current_function_name (), n_basic_blocks
);
6898 fprintf (file
, "%d bytes\n\n", bytes_used
);
6901 obstack_free (&gcse_obstack
, NULL
);
6902 free_reg_set_mem ();
6904 /* We are finished with alias. */
6905 end_alias_analysis ();
6906 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
6911 /* Return true if the graph is too expensive to optimize. PASS is the
6912 optimization about to be performed. */
6915 is_too_expensive (const char *pass
)
6917 /* Trying to perform global optimizations on flow graphs which have
6918 a high connectivity will take a long time and is unlikely to be
6919 particularly useful.
6921 In normal circumstances a cfg should have about twice as many
6922 edges as blocks. But we do not want to punish small functions
6923 which have a couple switch statements. Rather than simply
6924 threshold the number of blocks, uses something with a more
6925 graceful degradation. */
6926 if (n_edges
> 20000 + n_basic_blocks
* 4)
6928 if (warn_disabled_optimization
)
6929 warning ("%s: %d basic blocks and %d edges/basic block",
6930 pass
, n_basic_blocks
, n_edges
/ n_basic_blocks
);
6935 /* If allocating memory for the cprop bitmap would take up too much
6936 storage it's better just to disable the optimization. */
6938 * SBITMAP_SET_SIZE (max_reg_num ())
6939 * sizeof (SBITMAP_ELT_TYPE
)) > MAX_GCSE_MEMORY
)
6941 if (warn_disabled_optimization
)
6942 warning ("%s: %d basic blocks and %d registers",
6943 pass
, n_basic_blocks
, max_reg_num ());
6951 /* The following code implements gcse after reload, the purpose of this
6952 pass is to cleanup redundant loads generated by reload and other
6953 optimizations that come after gcse. It searches for simple inter-block
6954 redundancies and tries to eliminate them by adding moves and loads
6957 /* The following structure holds the information about the occurrences of
6958 the redundant instructions. */
6961 struct unoccr
*next
;
6966 static bool reg_used_on_edge (rtx
, edge
);
6967 static rtx
reg_set_between_after_reload_p (rtx
, rtx
, rtx
);
6968 static rtx
reg_used_between_after_reload_p (rtx
, rtx
, rtx
);
6969 static rtx
get_avail_load_store_reg (rtx
);
6970 static bool is_jump_table_basic_block (basic_block
);
6971 static bool bb_has_well_behaved_predecessors (basic_block
);
6972 static struct occr
* get_bb_avail_insn (basic_block
, struct occr
*);
6973 static void hash_scan_set_after_reload (rtx
, rtx
, struct hash_table
*);
6974 static void compute_hash_table_after_reload (struct hash_table
*);
6975 static void eliminate_partially_redundant_loads (basic_block
,
6978 static void gcse_after_reload (void);
6979 static struct occr
* get_bb_avail_insn (basic_block
, struct occr
*);
6980 void gcse_after_reload_main (rtx
, FILE *);
6983 /* Check if register REG is used in any insn waiting to be inserted on E.
6984 Assumes no such insn can be a CALL_INSN; if so call reg_used_between_p
6985 with PREV(insn),NEXT(insn) instead of calling
6986 reg_overlap_mentioned_p. */
6989 reg_used_on_edge (rtx reg
, edge e
)
6993 for (insn
= e
->insns
.r
; insn
; insn
= NEXT_INSN (insn
))
6994 if (INSN_P (insn
) && reg_overlap_mentioned_p (reg
, PATTERN (insn
)))
7000 /* Return the insn that sets register REG or clobbers it in between
7001 FROM_INSN and TO_INSN (exclusive of those two).
7002 Just like reg_set_between but for hard registers and not pseudos. */
7005 reg_set_between_after_reload_p (rtx reg
, rtx from_insn
, rtx to_insn
)
7012 regno
= REGNO (reg
);
7014 /* We are called after register allocation. */
7015 if (regno
>= FIRST_PSEUDO_REGISTER
)
7018 if (from_insn
== to_insn
)
7021 for (insn
= NEXT_INSN (from_insn
);
7023 insn
= NEXT_INSN (insn
))
7027 if (FIND_REG_INC_NOTE (insn
, reg
)
7029 && call_used_regs
[regno
])
7030 || find_reg_fusage (insn
, CLOBBER
, reg
))
7033 if (set_of (reg
, insn
) != NULL_RTX
)
7039 /* Return the insn that uses register REG in between FROM_INSN and TO_INSN
7040 (exclusive of those two). Similar to reg_used_between but for hard
7041 registers and not pseudos. */
7044 reg_used_between_after_reload_p (rtx reg
, rtx from_insn
, rtx to_insn
)
7051 regno
= REGNO (reg
);
7053 /* We are called after register allocation. */
7054 if (regno
>= FIRST_PSEUDO_REGISTER
)
7056 if (from_insn
== to_insn
)
7059 for (insn
= NEXT_INSN (from_insn
);
7061 insn
= NEXT_INSN (insn
))
7063 && (reg_overlap_mentioned_p (reg
, PATTERN (insn
))
7065 && call_used_regs
[regno
])
7066 || find_reg_fusage (insn
, USE
, reg
)
7067 || find_reg_fusage (insn
, CLOBBER
, reg
)))
7072 /* Return the loaded/stored register of a load/store instruction. */
7075 get_avail_load_store_reg (rtx insn
)
7077 if (REG_P (SET_DEST (PATTERN (insn
)))) /* A load. */
7078 return SET_DEST(PATTERN(insn
));
7079 if (REG_P (SET_SRC (PATTERN (insn
)))) /* A store. */
7080 return SET_SRC (PATTERN (insn
));
7084 /* Don't handle ABNORMAL edges or jump tables. */
7087 is_jump_table_basic_block (basic_block bb
)
7089 rtx insn
= BB_END (bb
);
7091 if (JUMP_TABLE_DATA_P (insn
))
7096 /* Return nonzero if the predecessors of BB are "well behaved". */
7099 bb_has_well_behaved_predecessors (basic_block bb
)
7103 if (EDGE_COUNT (bb
->preds
) == 0)
7105 FOR_EACH_EDGE (pred
, bb
->preds
)
7107 if (((pred
->flags
& EDGE_ABNORMAL
) && EDGE_CRITICAL_P (pred
))
7108 || is_jump_table_basic_block (pred
->src
))
7116 /* Search for the occurrences of expression in BB. */
7119 get_bb_avail_insn (basic_block bb
, struct occr
*occr
)
7121 for (; occr
!= NULL
; occr
= occr
->next
)
7122 if (BLOCK_FOR_INSN (occr
->insn
)->index
== bb
->index
)
7127 /* Perform partial GCSE pass after reload, try to eliminate redundant loads
7128 created by the reload pass. We try to look for a full or partial
7129 redundant loads fed by one or more loads/stores in predecessor BBs,
7130 and try adding loads to make them fully redundant. We also check if
7131 it's worth adding loads to be able to delete the redundant load.
7134 1. Build available expressions hash table:
7135 For each load/store instruction, if the loaded/stored memory didn't
7136 change until the end of the basic block add this memory expression to
7138 2. Perform Redundancy elimination:
7139 For each load instruction do the following:
7140 perform partial redundancy elimination, check if it's worth adding
7141 loads to make the load fully redundant. If so add loads and
7142 register copies and delete the load.
7145 if loaded register is used/defined between load and some store,
7146 look for some other free register between load and all its stores,
7147 and replace load with a copy from this register to the loaded
7151 /* This handles the case where several stores feed a partially redundant
7152 load. It checks if the redundancy elimination is possible and if it's
7156 eliminate_partially_redundant_loads (basic_block bb
, rtx insn
,
7160 rtx avail_insn
= NULL_RTX
;
7163 struct occr
*a_occr
;
7164 struct unoccr
*occr
, *avail_occrs
= NULL
;
7165 struct unoccr
*unoccr
, *unavail_occrs
= NULL
;
7167 gcov_type ok_count
= 0; /* Redundant load execution count. */
7168 gcov_type critical_count
= 0; /* Execution count of critical edges. */
7170 /* The execution count of the loads to be added to make the
7171 load fully redundant. */
7172 gcov_type not_ok_count
= 0;
7173 basic_block pred_bb
;
7175 pat
= PATTERN (insn
);
7176 dest
= SET_DEST (pat
);
7177 /* Check that the loaded register is not used, set, or killed from the
7178 beginning of the block. */
7179 if (reg_used_between_after_reload_p (dest
,
7180 PREV_INSN (BB_HEAD (bb
)), insn
)
7181 || reg_set_between_after_reload_p (dest
,
7182 PREV_INSN (BB_HEAD (bb
)), insn
))
7185 /* Check potential for replacing load with copy for predecessors. */
7186 FOR_EACH_EDGE (pred
, bb
->preds
)
7188 rtx next_pred_bb_end
;
7190 avail_insn
= NULL_RTX
;
7191 pred_bb
= pred
->src
;
7192 next_pred_bb_end
= NEXT_INSN (BB_END (pred_bb
));
7193 for (a_occr
= get_bb_avail_insn (pred_bb
, expr
->avail_occr
); a_occr
;
7194 a_occr
= get_bb_avail_insn (pred_bb
, a_occr
->next
))
7196 /* Check if the loaded register is not used. */
7197 avail_insn
= a_occr
->insn
;
7198 if (! (avail_reg
= get_avail_load_store_reg (avail_insn
)))
7200 /* Make sure we can generate a move from register avail_reg to
7202 extract_insn (gen_move_insn (copy_rtx (dest
),
7203 copy_rtx (avail_reg
)));
7204 if (! constrain_operands (1)
7205 || reg_killed_on_edge (avail_reg
, pred
)
7206 || reg_used_on_edge (dest
, pred
))
7211 if (! reg_set_between_after_reload_p (avail_reg
, avail_insn
,
7213 /* AVAIL_INSN remains non-null. */
7218 if (avail_insn
!= NULL_RTX
)
7221 ok_count
+= pred
->count
;
7222 if (EDGE_CRITICAL_P (pred
))
7223 critical_count
+= pred
->count
;
7224 occr
= gmalloc (sizeof (struct unoccr
));
7225 occr
->insn
= avail_insn
;
7227 occr
->next
= avail_occrs
;
7232 not_ok_count
+= pred
->count
;
7233 if (EDGE_CRITICAL_P (pred
))
7234 critical_count
+= pred
->count
;
7235 unoccr
= gmalloc (sizeof (struct unoccr
));
7236 unoccr
->insn
= NULL_RTX
;
7237 unoccr
->pred
= pred
;
7238 unoccr
->next
= unavail_occrs
;
7239 unavail_occrs
= unoccr
;
7244 if (npred_ok
== 0 /* No load can be replaced by copy. */
7245 || (optimize_size
&& npred_ok
> 1)) /* Prevent exploding the code. */
7248 /* Check if it's worth applying the partial redundancy elimination. */
7249 if (ok_count
< GCSE_AFTER_RELOAD_PARTIAL_FRACTION
* not_ok_count
)
7252 if (ok_count
< GCSE_AFTER_RELOAD_CRITICAL_FRACTION
* critical_count
)
7255 /* Generate moves to the loaded register from where
7256 the memory is available. */
7257 for (occr
= avail_occrs
; occr
; occr
= occr
->next
)
7259 avail_insn
= occr
->insn
;
7261 /* Set avail_reg to be the register having the value of the
7263 avail_reg
= get_avail_load_store_reg (avail_insn
);
7267 insert_insn_on_edge (gen_move_insn (copy_rtx (dest
),
7268 copy_rtx (avail_reg
)),
7273 "GCSE AFTER reload generating move from %d to %d on \
7274 edge from %d to %d\n",
7281 /* Regenerate loads where the memory is unavailable. */
7282 for (unoccr
= unavail_occrs
; unoccr
; unoccr
= unoccr
->next
)
7284 pred
= unoccr
->pred
;
7285 insert_insn_on_edge (copy_insn (PATTERN (insn
)), pred
);
7289 "GCSE AFTER reload: generating on edge from %d to %d\
7295 /* Delete the insn if it is not available in this block and mark it
7296 for deletion if it is available. If insn is available it may help
7297 discover additional redundancies, so mark it for later deletion.*/
7298 for (a_occr
= get_bb_avail_insn (bb
, expr
->avail_occr
);
7299 a_occr
&& (a_occr
->insn
!= insn
);
7300 a_occr
= get_bb_avail_insn (bb
, a_occr
->next
));
7305 a_occr
->deleted_p
= 1;
7309 while (unavail_occrs
)
7311 struct unoccr
*temp
= unavail_occrs
->next
;
7312 free (unavail_occrs
);
7313 unavail_occrs
= temp
;
7318 struct unoccr
*temp
= avail_occrs
->next
;
7324 /* Performing the redundancy elimination as described before. */
7327 gcse_after_reload (void)
7335 /* Note we start at block 1. */
7337 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
7341 ENTRY_BLOCK_PTR
->next_bb
->next_bb
,
7345 if (! bb_has_well_behaved_predecessors (bb
))
7348 /* Do not try this optimization on cold basic blocks. */
7349 if (probably_cold_bb_p (bb
))
7352 reset_opr_set_tables ();
7354 for (insn
= BB_HEAD (bb
);
7356 && insn
!= NEXT_INSN (BB_END (bb
));
7357 insn
= NEXT_INSN (insn
))
7359 /* Is it a load - of the form (set (reg) (mem))? */
7360 if (NONJUMP_INSN_P (insn
)
7361 && GET_CODE (PATTERN (insn
)) == SET
7362 && REG_P (SET_DEST (PATTERN (insn
)))
7363 && MEM_P (SET_SRC (PATTERN (insn
))))
7365 rtx pat
= PATTERN (insn
);
7366 rtx src
= SET_SRC (pat
);
7369 if (general_operand (src
, GET_MODE (src
))
7370 /* Is the expression recorded? */
7371 && (expr
= lookup_expr (src
, &expr_hash_table
)) != NULL
7372 /* Are the operands unchanged since the start of the
7374 && oprs_not_set_p (src
, insn
)
7375 && ! MEM_VOLATILE_P (src
)
7376 && GET_MODE (src
) != BLKmode
7377 && !(flag_non_call_exceptions
&& may_trap_p (src
))
7378 && !side_effects_p (src
))
7380 /* We now have a load (insn) and an available memory at
7381 its BB start (expr). Try to remove the loads if it is
7383 eliminate_partially_redundant_loads (bb
, insn
, expr
);
7387 /* Keep track of everything modified by this insn. */
7389 mark_oprs_set (insn
);
7393 commit_edge_insertions ();
7395 /* Go over the expression hash table and delete insns that were
7396 marked for later deletion. */
7397 for (i
= 0; i
< expr_hash_table
.size
; i
++)
7399 for (expr
= expr_hash_table
.table
[i
];
7401 expr
= expr
->next_same_hash
)
7402 for (occr
= expr
->avail_occr
; occr
; occr
= occr
->next
)
7403 if (occr
->deleted_p
)
7404 delete_insn (occr
->insn
);
7408 /* Scan pattern PAT of INSN and add an entry to the hash TABLE.
7409 After reload we are interested in loads/stores only. */
7412 hash_scan_set_after_reload (rtx pat
, rtx insn
, struct hash_table
*table
)
7414 rtx src
= SET_SRC (pat
);
7415 rtx dest
= SET_DEST (pat
);
7417 if (! MEM_P (src
) && ! MEM_P (dest
))
7422 if (/* Don't GCSE something if we can't do a reg/reg copy. */
7423 can_copy_p (GET_MODE (dest
))
7424 /* GCSE commonly inserts instruction after the insn. We can't
7425 do that easily for EH_REGION notes so disable GCSE on these
7427 && ! find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
7428 /* Is SET_SRC something we want to gcse? */
7429 && general_operand (src
, GET_MODE (src
))
7430 /* Don't CSE a nop. */
7431 && ! set_noop_p (pat
)
7434 /* An expression is not available if its operands are
7435 subsequently modified, including this insn. */
7436 if (oprs_available_p (src
, insn
))
7437 insert_expr_in_table (src
, GET_MODE (dest
), insn
, 0, 1, table
);
7440 else if (REG_P (src
))
7442 /* Only record sets of pseudo-regs in the hash table. */
7443 if (/* Don't GCSE something if we can't do a reg/reg copy. */
7444 can_copy_p (GET_MODE (src
))
7445 /* GCSE commonly inserts instruction after the insn. We can't
7446 do that easily for EH_REGION notes so disable GCSE on these
7448 && ! find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
7449 /* Is SET_DEST something we want to gcse? */
7450 && general_operand (dest
, GET_MODE (dest
))
7451 /* Don't CSE a nop. */
7452 && ! set_noop_p (pat
)
7454 && ! (flag_float_store
&& FLOAT_MODE_P (GET_MODE (dest
)))
7455 /* Check if the memory expression is killed after insn. */
7456 && ! load_killed_in_block_p (BLOCK_FOR_INSN (insn
),
7457 INSN_CUID (insn
) + 1,
7460 && oprs_unchanged_p (XEXP (dest
, 0), insn
, 1))
7462 insert_expr_in_table (dest
, GET_MODE (dest
), insn
, 0, 1, table
);
7468 /* Create hash table of memory expressions available at end of basic
7472 compute_hash_table_after_reload (struct hash_table
*table
)
7478 /* Initialize count of number of entries in hash table. */
7480 memset ((char *) table
->table
, 0,
7481 table
->size
* sizeof (struct expr
*));
7483 /* While we compute the hash table we also compute a bit array of which
7484 registers are set in which blocks. */
7485 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
7487 /* Re-cache any INSN_LIST nodes we have allocated. */
7488 clear_modify_mem_tables ();
7490 /* Some working arrays used to track first and last set in each block. */
7491 reg_avail_info
= gmalloc (max_gcse_regno
* sizeof (struct reg_avail_info
));
7493 for (i
= 0; i
< max_gcse_regno
; ++i
)
7494 reg_avail_info
[i
].last_bb
= NULL
;
7496 FOR_EACH_BB (current_bb
)
7501 /* First pass over the instructions records information used to
7502 determine when registers and memory are first and last set. */
7503 for (insn
= BB_HEAD (current_bb
);
7504 insn
&& insn
!= NEXT_INSN (BB_END (current_bb
));
7505 insn
= NEXT_INSN (insn
))
7507 if (! INSN_P (insn
))
7512 bool clobbers_all
= false;
7514 #ifdef NON_SAVING_SETJMP
7515 if (NON_SAVING_SETJMP
7516 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
7517 clobbers_all
= true;
7520 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
7522 || TEST_HARD_REG_BIT (regs_invalidated_by_call
,
7524 record_last_reg_set_info (insn
, regno
);
7529 note_stores (PATTERN (insn
), record_last_set_info
, insn
);
7531 if (GET_CODE (PATTERN (insn
)) == SET
)
7535 src
= SET_SRC (PATTERN (insn
));
7536 dest
= SET_DEST (PATTERN (insn
));
7537 if (MEM_P (src
) && auto_inc_p (XEXP (src
, 0)))
7539 regno
= REGNO (XEXP (XEXP (src
, 0), 0));
7540 record_last_reg_set_info (insn
, regno
);
7542 if (MEM_P (dest
) && auto_inc_p (XEXP (dest
, 0)))
7544 regno
= REGNO (XEXP (XEXP (dest
, 0), 0));
7545 record_last_reg_set_info (insn
, regno
);
7550 /* The next pass builds the hash table. */
7551 for (insn
= BB_HEAD (current_bb
);
7552 insn
&& insn
!= NEXT_INSN (BB_END (current_bb
));
7553 insn
= NEXT_INSN (insn
))
7554 if (INSN_P (insn
) && GET_CODE (PATTERN (insn
)) == SET
)
7555 if (! find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
7556 hash_scan_set_after_reload (PATTERN (insn
), insn
, table
);
7559 free (reg_avail_info
);
7560 reg_avail_info
= NULL
;
7564 /* Main entry point of the GCSE after reload - clean some redundant loads
7568 gcse_after_reload_main (rtx f
, FILE* file
)
7570 gcse_subst_count
= 0;
7571 gcse_create_count
= 0;
7575 gcc_obstack_init (&gcse_obstack
);
7578 /* We need alias. */
7579 init_alias_analysis ();
7581 max_gcse_regno
= max_reg_num ();
7583 alloc_reg_set_mem (max_gcse_regno
);
7585 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
7586 compute_hash_table_after_reload (&expr_hash_table
);
7589 dump_hash_table (gcse_file
, "Expression", &expr_hash_table
);
7591 if (expr_hash_table
.n_elems
> 0)
7592 gcse_after_reload ();
7594 free_hash_table (&expr_hash_table
);
7597 free_reg_set_mem ();
7599 /* We are finished with alias. */
7600 end_alias_analysis ();
7602 obstack_free (&gcse_obstack
, NULL
);
7605 #include "gt-gcse.h"