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"
173 /* Propagate flow information through back edges and thus enable PRE's
174 moving loop invariant calculations out of loops.
176 Originally this tended to create worse overall code, but several
177 improvements during the development of PRE seem to have made following
178 back edges generally a win.
180 Note much of the loop invariant code motion done here would normally
181 be done by loop.c, which has more heuristics for when to move invariants
182 out of loops. At some point we might need to move some of those
183 heuristics into gcse.c. */
185 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
186 are a superset of those done by GCSE.
188 We perform the following steps:
190 1) Compute basic block information.
192 2) Compute table of places where registers are set.
194 3) Perform copy/constant propagation.
196 4) Perform global cse using lazy code motion if not optimizing
197 for size, or code hoisting if we are.
199 5) Perform another pass of copy/constant propagation.
201 Two passes of copy/constant propagation are done because the first one
202 enables more GCSE and the second one helps to clean up the copies that
203 GCSE creates. This is needed more for PRE than for Classic because Classic
204 GCSE will try to use an existing register containing the common
205 subexpression rather than create a new one. This is harder to do for PRE
206 because of the code motion (which Classic GCSE doesn't do).
208 Expressions we are interested in GCSE-ing are of the form
209 (set (pseudo-reg) (expression)).
210 Function want_to_gcse_p says what these are.
212 PRE handles moving invariant expressions out of loops (by treating them as
213 partially redundant).
215 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
216 assignment) based GVN (global value numbering). L. T. Simpson's paper
217 (Rice University) on value numbering is a useful reference for this.
219 **********************
221 We used to support multiple passes but there are diminishing returns in
222 doing so. The first pass usually makes 90% of the changes that are doable.
223 A second pass can make a few more changes made possible by the first pass.
224 Experiments show any further passes don't make enough changes to justify
227 A study of spec92 using an unlimited number of passes:
228 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
229 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
230 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
232 It was found doing copy propagation between each pass enables further
235 PRE is quite expensive in complicated functions because the DFA can take
236 a while to converge. Hence we only perform one pass. The parameter
237 max-gcse-passes can be modified if one wants to experiment.
239 **********************
241 The steps for PRE are:
243 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
245 2) Perform the data flow analysis for PRE.
247 3) Delete the redundant instructions
249 4) Insert the required copies [if any] that make the partially
250 redundant instructions fully redundant.
252 5) For other reaching expressions, insert an instruction to copy the value
253 to a newly created pseudo that will reach the redundant instruction.
255 The deletion is done first so that when we do insertions we
256 know which pseudo reg to use.
258 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
259 argue it is not. The number of iterations for the algorithm to converge
260 is typically 2-4 so I don't view it as that expensive (relatively speaking).
262 PRE GCSE depends heavily on the second CSE pass to clean up the copies
263 we create. To make an expression reach the place where it's redundant,
264 the result of the expression is copied to a new register, and the redundant
265 expression is deleted by replacing it with this new register. Classic GCSE
266 doesn't have this problem as much as it computes the reaching defs of
267 each register in each block and thus can try to use an existing register.
269 **********************
271 A fair bit of simplicity is created by creating small functions for simple
272 tasks, even when the function is only called in one place. This may
273 measurably slow things down [or may not] by creating more function call
274 overhead than is necessary. The source is laid out so that it's trivial
275 to make the affected functions inline so that one can measure what speed
276 up, if any, can be achieved, and maybe later when things settle things can
279 Help stamp out big monolithic functions! */
281 /* GCSE global vars. */
284 static FILE *gcse_file
;
286 /* Note whether or not we should run jump optimization after gcse. We
287 want to do this for two cases.
289 * If we changed any jumps via cprop.
291 * If we added any labels via edge splitting. */
292 static int run_jump_opt_after_gcse
;
294 /* Bitmaps are normally not included in debugging dumps.
295 However it's useful to be able to print them from GDB.
296 We could create special functions for this, but it's simpler to
297 just allow passing stderr to the dump_foo fns. Since stderr can
298 be a macro, we store a copy here. */
299 static FILE *debug_stderr
;
301 /* An obstack for our working variables. */
302 static struct obstack gcse_obstack
;
304 struct reg_use
{rtx reg_rtx
; };
306 /* Hash table of expressions. */
310 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
312 /* Index in the available expression bitmaps. */
314 /* Next entry with the same hash. */
315 struct expr
*next_same_hash
;
316 /* List of anticipatable occurrences in basic blocks in the function.
317 An "anticipatable occurrence" is one that is the first occurrence in the
318 basic block, the operands are not modified in the basic block prior
319 to the occurrence and the output is not used between the start of
320 the block and the occurrence. */
321 struct occr
*antic_occr
;
322 /* List of available occurrence in basic blocks in the function.
323 An "available occurrence" is one that is the last occurrence in the
324 basic block and the operands are not modified by following statements in
325 the basic block [including this insn]. */
326 struct occr
*avail_occr
;
327 /* Non-null if the computation is PRE redundant.
328 The value is the newly created pseudo-reg to record a copy of the
329 expression in all the places that reach the redundant copy. */
333 /* Occurrence of an expression.
334 There is one per basic block. If a pattern appears more than once the
335 last appearance is used [or first for anticipatable expressions]. */
339 /* Next occurrence of this expression. */
341 /* The insn that computes the expression. */
343 /* Nonzero if this [anticipatable] occurrence has been deleted. */
345 /* Nonzero if this [available] occurrence has been copied to
347 /* ??? This is mutually exclusive with deleted_p, so they could share
352 /* Expression and copy propagation hash tables.
353 Each hash table is an array of buckets.
354 ??? It is known that if it were an array of entries, structure elements
355 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
356 not clear whether in the final analysis a sufficient amount of memory would
357 be saved as the size of the available expression bitmaps would be larger
358 [one could build a mapping table without holes afterwards though].
359 Someday I'll perform the computation and figure it out. */
364 This is an array of `expr_hash_table_size' elements. */
367 /* Size of the hash table, in elements. */
370 /* Number of hash table elements. */
371 unsigned int n_elems
;
373 /* Whether the table is expression of copy propagation one. */
377 /* Expression hash table. */
378 static struct hash_table expr_hash_table
;
380 /* Copy propagation hash table. */
381 static struct hash_table set_hash_table
;
383 /* Mapping of uids to cuids.
384 Only real insns get cuids. */
385 static int *uid_cuid
;
387 /* Highest UID in UID_CUID. */
390 /* Get the cuid of an insn. */
391 #ifdef ENABLE_CHECKING
392 #define INSN_CUID(INSN) \
393 (gcc_assert (INSN_UID (INSN) <= max_uid), uid_cuid[INSN_UID (INSN)])
395 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
398 /* Number of cuids. */
401 /* Mapping of cuids to insns. */
402 static rtx
*cuid_insn
;
404 /* Get insn from cuid. */
405 #define CUID_INSN(CUID) (cuid_insn[CUID])
407 /* Maximum register number in function prior to doing gcse + 1.
408 Registers created during this pass have regno >= max_gcse_regno.
409 This is named with "gcse" to not collide with global of same name. */
410 static unsigned int max_gcse_regno
;
412 /* Table of registers that are modified.
414 For each register, each element is a list of places where the pseudo-reg
417 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
418 requires knowledge of which blocks kill which regs [and thus could use
419 a bitmap instead of the lists `reg_set_table' uses].
421 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
422 num-regs) [however perhaps it may be useful to keep the data as is]. One
423 advantage of recording things this way is that `reg_set_table' is fairly
424 sparse with respect to pseudo regs but for hard regs could be fairly dense
425 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
426 up functions like compute_transp since in the case of pseudo-regs we only
427 need to iterate over the number of times a pseudo-reg is set, not over the
428 number of basic blocks [clearly there is a bit of a slow down in the cases
429 where a pseudo is set more than once in a block, however it is believed
430 that the net effect is to speed things up]. This isn't done for hard-regs
431 because recording call-clobbered hard-regs in `reg_set_table' at each
432 function call can consume a fair bit of memory, and iterating over
433 hard-regs stored this way in compute_transp will be more expensive. */
435 typedef struct reg_set
437 /* The next setting of this register. */
438 struct reg_set
*next
;
439 /* The insn where it was set. */
443 static reg_set
**reg_set_table
;
445 /* Size of `reg_set_table'.
446 The table starts out at max_gcse_regno + slop, and is enlarged as
448 static int reg_set_table_size
;
450 /* Amount to grow `reg_set_table' by when it's full. */
451 #define REG_SET_TABLE_SLOP 100
453 /* This is a list of expressions which are MEMs and will be used by load
455 Load motion tracks MEMs which aren't killed by
456 anything except itself. (i.e., loads and stores to a single location).
457 We can then allow movement of these MEM refs with a little special
458 allowance. (all stores copy the same value to the reaching reg used
459 for the loads). This means all values used to store into memory must have
460 no side effects so we can re-issue the setter value.
461 Store Motion uses this structure as an expression table to track stores
462 which look interesting, and might be moveable towards the exit block. */
466 struct expr
* expr
; /* Gcse expression reference for LM. */
467 rtx pattern
; /* Pattern of this mem. */
468 rtx pattern_regs
; /* List of registers mentioned by the mem. */
469 rtx loads
; /* INSN list of loads seen. */
470 rtx stores
; /* INSN list of stores seen. */
471 struct ls_expr
* next
; /* Next in the list. */
472 int invalid
; /* Invalid for some reason. */
473 int index
; /* If it maps to a bitmap index. */
474 unsigned int hash_index
; /* Index when in a hash table. */
475 rtx reaching_reg
; /* Register to use when re-writing. */
478 /* Array of implicit set patterns indexed by basic block index. */
479 static rtx
*implicit_sets
;
481 /* Head of the list of load/store memory refs. */
482 static struct ls_expr
* pre_ldst_mems
= NULL
;
484 /* Bitmap containing one bit for each register in the program.
485 Used when performing GCSE to track which registers have been set since
486 the start of the basic block. */
487 static regset reg_set_bitmap
;
489 /* For each block, a bitmap of registers set in the block.
490 This is used by compute_transp.
491 It is computed during hash table computation and not by compute_sets
492 as it includes registers added since the last pass (or between cprop and
493 gcse) and it's currently not easy to realloc sbitmap vectors. */
494 static sbitmap
*reg_set_in_block
;
496 /* Array, indexed by basic block number for a list of insns which modify
497 memory within that block. */
498 static rtx
* modify_mem_list
;
499 static bitmap modify_mem_list_set
;
501 /* This array parallels modify_mem_list, but is kept canonicalized. */
502 static rtx
* canon_modify_mem_list
;
503 static bitmap canon_modify_mem_list_set
;
505 /* Various variables for statistics gathering. */
507 /* Memory used in a pass.
508 This isn't intended to be absolutely precise. Its intent is only
509 to keep an eye on memory usage. */
510 static int bytes_used
;
512 /* GCSE substitutions made. */
513 static int gcse_subst_count
;
514 /* Number of copy instructions created. */
515 static int gcse_create_count
;
516 /* Number of local constants propagated. */
517 static int local_const_prop_count
;
518 /* Number of local copys propagated. */
519 static int local_copy_prop_count
;
520 /* Number of global constants propagated. */
521 static int global_const_prop_count
;
522 /* Number of global copys propagated. */
523 static int global_copy_prop_count
;
525 /* For available exprs */
526 static sbitmap
*ae_kill
, *ae_gen
;
528 /* Objects of this type are passed around by the null-pointer check
530 struct null_pointer_info
532 /* The basic block being processed. */
533 basic_block current_block
;
534 /* The first register to be handled in this pass. */
535 unsigned int min_reg
;
536 /* One greater than the last register to be handled in this pass. */
537 unsigned int max_reg
;
538 sbitmap
*nonnull_local
;
539 sbitmap
*nonnull_killed
;
542 static void compute_can_copy (void);
543 static void *gmalloc (size_t) ATTRIBUTE_MALLOC
;
544 static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC
;
545 static void *grealloc (void *, size_t);
546 static void *gcse_alloc (unsigned long);
547 static void alloc_gcse_mem (rtx
);
548 static void free_gcse_mem (void);
549 static void alloc_reg_set_mem (int);
550 static void free_reg_set_mem (void);
551 static void record_one_set (int, rtx
);
552 static void replace_one_set (int, rtx
, rtx
);
553 static void record_set_info (rtx
, rtx
, void *);
554 static void compute_sets (rtx
);
555 static void hash_scan_insn (rtx
, struct hash_table
*, int);
556 static void hash_scan_set (rtx
, rtx
, struct hash_table
*);
557 static void hash_scan_clobber (rtx
, rtx
, struct hash_table
*);
558 static void hash_scan_call (rtx
, rtx
, struct hash_table
*);
559 static int want_to_gcse_p (rtx
);
560 static bool can_assign_to_reg_p (rtx
);
561 static bool gcse_constant_p (rtx
);
562 static int oprs_unchanged_p (rtx
, rtx
, int);
563 static int oprs_anticipatable_p (rtx
, rtx
);
564 static int oprs_available_p (rtx
, rtx
);
565 static void insert_expr_in_table (rtx
, enum machine_mode
, rtx
, int, int,
566 struct hash_table
*);
567 static void insert_set_in_table (rtx
, rtx
, struct hash_table
*);
568 static unsigned int hash_expr (rtx
, enum machine_mode
, int *, int);
569 static unsigned int hash_set (int, int);
570 static int expr_equiv_p (rtx
, rtx
);
571 static void record_last_reg_set_info (rtx
, int);
572 static void record_last_mem_set_info (rtx
);
573 static void record_last_set_info (rtx
, rtx
, void *);
574 static void compute_hash_table (struct hash_table
*);
575 static void alloc_hash_table (int, struct hash_table
*, int);
576 static void free_hash_table (struct hash_table
*);
577 static void compute_hash_table_work (struct hash_table
*);
578 static void dump_hash_table (FILE *, const char *, struct hash_table
*);
579 static struct expr
*lookup_set (unsigned int, struct hash_table
*);
580 static struct expr
*next_set (unsigned int, struct expr
*);
581 static void reset_opr_set_tables (void);
582 static int oprs_not_set_p (rtx
, rtx
);
583 static void mark_call (rtx
);
584 static void mark_set (rtx
, rtx
);
585 static void mark_clobber (rtx
, rtx
);
586 static void mark_oprs_set (rtx
);
587 static void alloc_cprop_mem (int, int);
588 static void free_cprop_mem (void);
589 static void compute_transp (rtx
, int, sbitmap
*, int);
590 static void compute_transpout (void);
591 static void compute_local_properties (sbitmap
*, sbitmap
*, sbitmap
*,
592 struct hash_table
*);
593 static void compute_cprop_data (void);
594 static void find_used_regs (rtx
*, void *);
595 static int try_replace_reg (rtx
, rtx
, rtx
);
596 static struct expr
*find_avail_set (int, rtx
);
597 static int cprop_jump (basic_block
, rtx
, rtx
, rtx
, rtx
);
598 static void mems_conflict_for_gcse_p (rtx
, rtx
, void *);
599 static int load_killed_in_block_p (basic_block
, int, rtx
, int);
600 static void canon_list_insert (rtx
, rtx
, void *);
601 static int cprop_insn (rtx
, int);
602 static int cprop (int);
603 static void find_implicit_sets (void);
604 static int one_cprop_pass (int, int, int);
605 static bool constprop_register (rtx
, rtx
, rtx
, int);
606 static struct expr
*find_bypass_set (int, int);
607 static bool reg_killed_on_edge (rtx
, edge
);
608 static int bypass_block (basic_block
, rtx
, rtx
);
609 static int bypass_conditional_jumps (void);
610 static void alloc_pre_mem (int, int);
611 static void free_pre_mem (void);
612 static void compute_pre_data (void);
613 static int pre_expr_reaches_here_p (basic_block
, struct expr
*,
615 static void insert_insn_end_bb (struct expr
*, basic_block
, int);
616 static void pre_insert_copy_insn (struct expr
*, rtx
);
617 static void pre_insert_copies (void);
618 static int pre_delete (void);
619 static int pre_gcse (void);
620 static int one_pre_gcse_pass (int);
621 static void add_label_notes (rtx
, rtx
);
622 static void alloc_code_hoist_mem (int, int);
623 static void free_code_hoist_mem (void);
624 static void compute_code_hoist_vbeinout (void);
625 static void compute_code_hoist_data (void);
626 static int hoist_expr_reaches_here_p (basic_block
, int, basic_block
, char *);
627 static void hoist_code (void);
628 static int one_code_hoisting_pass (void);
629 static rtx
process_insert_insn (struct expr
*);
630 static int pre_edge_insert (struct edge_list
*, struct expr
**);
631 static int pre_expr_reaches_here_p_work (basic_block
, struct expr
*,
632 basic_block
, char *);
633 static struct ls_expr
* ldst_entry (rtx
);
634 static void free_ldst_entry (struct ls_expr
*);
635 static void free_ldst_mems (void);
636 static void print_ldst_list (FILE *);
637 static struct ls_expr
* find_rtx_in_ldst (rtx
);
638 static int enumerate_ldsts (void);
639 static inline struct ls_expr
* first_ls_expr (void);
640 static inline struct ls_expr
* next_ls_expr (struct ls_expr
*);
641 static int simple_mem (rtx
);
642 static void invalidate_any_buried_refs (rtx
);
643 static void compute_ld_motion_mems (void);
644 static void trim_ld_motion_mems (void);
645 static void update_ld_motion_stores (struct expr
*);
646 static void reg_set_info (rtx
, rtx
, void *);
647 static void reg_clear_last_set (rtx
, rtx
, void *);
648 static bool store_ops_ok (rtx
, int *);
649 static rtx
extract_mentioned_regs (rtx
);
650 static rtx
extract_mentioned_regs_helper (rtx
, rtx
);
651 static void find_moveable_store (rtx
, int *, int *);
652 static int compute_store_table (void);
653 static bool load_kills_store (rtx
, rtx
, int);
654 static bool find_loads (rtx
, rtx
, int);
655 static bool store_killed_in_insn (rtx
, rtx
, rtx
, int);
656 static bool store_killed_after (rtx
, rtx
, rtx
, basic_block
, int *, rtx
*);
657 static bool store_killed_before (rtx
, rtx
, rtx
, basic_block
, int *);
658 static void build_store_vectors (void);
659 static void insert_insn_start_bb (rtx
, basic_block
);
660 static int insert_store (struct ls_expr
*, edge
);
661 static void remove_reachable_equiv_notes (basic_block
, struct ls_expr
*);
662 static void replace_store_insn (rtx
, rtx
, basic_block
, struct ls_expr
*);
663 static void delete_store (struct ls_expr
*, basic_block
);
664 static void free_store_memory (void);
665 static void store_motion (void);
666 static void free_insn_expr_list_list (rtx
*);
667 static void clear_modify_mem_tables (void);
668 static void free_modify_mem_tables (void);
669 static rtx
gcse_emit_move_after (rtx
, rtx
, rtx
);
670 static void local_cprop_find_used_regs (rtx
*, void *);
671 static bool do_local_cprop (rtx
, rtx
, int, rtx
*);
672 static bool adjust_libcall_notes (rtx
, rtx
, rtx
, rtx
*);
673 static void local_cprop_pass (int);
674 static bool is_too_expensive (const char *);
677 /* Entry point for global common subexpression elimination.
678 F is the first instruction in the function. */
681 gcse_main (rtx f
, FILE *file
)
684 /* Bytes used at start of pass. */
685 int initial_bytes_used
;
686 /* Maximum number of bytes used by a pass. */
688 /* Point to release obstack data from for each pass. */
689 char *gcse_obstack_bottom
;
691 /* We do not construct an accurate cfg in functions which call
692 setjmp, so just punt to be safe. */
693 if (current_function_calls_setjmp
)
696 /* Assume that we do not need to run jump optimizations after gcse. */
697 run_jump_opt_after_gcse
= 0;
699 /* For calling dump_foo fns from gdb. */
700 debug_stderr
= stderr
;
703 /* Identify the basic block information for this function, including
704 successors and predecessors. */
705 max_gcse_regno
= max_reg_num ();
708 dump_flow_info (file
);
710 /* Return if there's nothing to do, or it is too expensive. */
711 if (n_basic_blocks
<= 1 || is_too_expensive (_("GCSE disabled")))
714 gcc_obstack_init (&gcse_obstack
);
718 init_alias_analysis ();
719 /* Record where pseudo-registers are set. This data is kept accurate
720 during each pass. ??? We could also record hard-reg information here
721 [since it's unchanging], however it is currently done during hash table
724 It may be tempting to compute MEM set information here too, but MEM sets
725 will be subject to code motion one day and thus we need to compute
726 information about memory sets when we build the hash tables. */
728 alloc_reg_set_mem (max_gcse_regno
);
732 initial_bytes_used
= bytes_used
;
734 gcse_obstack_bottom
= gcse_alloc (1);
736 while (changed
&& pass
< MAX_GCSE_PASSES
)
740 fprintf (file
, "GCSE pass %d\n\n", pass
+ 1);
742 /* Initialize bytes_used to the space for the pred/succ lists,
743 and the reg_set_table data. */
744 bytes_used
= initial_bytes_used
;
746 /* Each pass may create new registers, so recalculate each time. */
747 max_gcse_regno
= max_reg_num ();
751 /* Don't allow constant propagation to modify jumps
753 timevar_push (TV_CPROP1
);
754 changed
= one_cprop_pass (pass
+ 1, 0, 0);
755 timevar_pop (TV_CPROP1
);
761 timevar_push (TV_PRE
);
762 changed
|= one_pre_gcse_pass (pass
+ 1);
763 /* We may have just created new basic blocks. Release and
764 recompute various things which are sized on the number of
768 free_modify_mem_tables ();
769 modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
770 canon_modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
773 alloc_reg_set_mem (max_reg_num ());
775 run_jump_opt_after_gcse
= 1;
776 timevar_pop (TV_PRE
);
779 if (max_pass_bytes
< bytes_used
)
780 max_pass_bytes
= bytes_used
;
782 /* Free up memory, then reallocate for code hoisting. We can
783 not re-use the existing allocated memory because the tables
784 will not have info for the insns or registers created by
785 partial redundancy elimination. */
788 /* It does not make sense to run code hoisting unless we are optimizing
789 for code size -- it rarely makes programs faster, and can make
790 them bigger if we did partial redundancy elimination (when optimizing
791 for space, we don't run the partial redundancy algorithms). */
794 timevar_push (TV_HOIST
);
795 max_gcse_regno
= max_reg_num ();
797 changed
|= one_code_hoisting_pass ();
800 if (max_pass_bytes
< bytes_used
)
801 max_pass_bytes
= bytes_used
;
802 timevar_pop (TV_HOIST
);
807 fprintf (file
, "\n");
811 obstack_free (&gcse_obstack
, gcse_obstack_bottom
);
815 /* Do one last pass of copy propagation, including cprop into
816 conditional jumps. */
818 max_gcse_regno
= max_reg_num ();
820 /* This time, go ahead and allow cprop to alter jumps. */
821 timevar_push (TV_CPROP2
);
822 one_cprop_pass (pass
+ 1, 1, 0);
823 timevar_pop (TV_CPROP2
);
828 fprintf (file
, "GCSE of %s: %d basic blocks, ",
829 current_function_name (), n_basic_blocks
);
830 fprintf (file
, "%d pass%s, %d bytes\n\n",
831 pass
, pass
> 1 ? "es" : "", max_pass_bytes
);
834 obstack_free (&gcse_obstack
, NULL
);
837 /* We are finished with alias. */
838 end_alias_analysis ();
839 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
841 if (!optimize_size
&& flag_gcse_sm
)
843 timevar_push (TV_LSM
);
845 timevar_pop (TV_LSM
);
848 /* Record where pseudo-registers are set. */
849 return run_jump_opt_after_gcse
;
852 /* Misc. utilities. */
854 /* Nonzero for each mode that supports (set (reg) (reg)).
855 This is trivially true for integer and floating point values.
856 It may or may not be true for condition codes. */
857 static char can_copy
[(int) NUM_MACHINE_MODES
];
859 /* Compute which modes support reg/reg copy operations. */
862 compute_can_copy (void)
865 #ifndef AVOID_CCMODE_COPIES
868 memset (can_copy
, 0, NUM_MACHINE_MODES
);
871 for (i
= 0; i
< NUM_MACHINE_MODES
; i
++)
872 if (GET_MODE_CLASS (i
) == MODE_CC
)
874 #ifdef AVOID_CCMODE_COPIES
877 reg
= gen_rtx_REG ((enum machine_mode
) i
, LAST_VIRTUAL_REGISTER
+ 1);
878 insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, reg
));
879 if (recog (PATTERN (insn
), insn
, NULL
) >= 0)
889 /* Returns whether the mode supports reg/reg copy operations. */
892 can_copy_p (enum machine_mode mode
)
894 static bool can_copy_init_p
= false;
896 if (! can_copy_init_p
)
899 can_copy_init_p
= true;
902 return can_copy
[mode
] != 0;
905 /* Cover function to xmalloc to record bytes allocated. */
908 gmalloc (size_t size
)
911 return xmalloc (size
);
914 /* Cover function to xcalloc to record bytes allocated. */
917 gcalloc (size_t nelem
, size_t elsize
)
919 bytes_used
+= nelem
* elsize
;
920 return xcalloc (nelem
, elsize
);
923 /* Cover function to xrealloc.
924 We don't record the additional size since we don't know it.
925 It won't affect memory usage stats much anyway. */
928 grealloc (void *ptr
, size_t size
)
930 return xrealloc (ptr
, size
);
933 /* Cover function to obstack_alloc. */
936 gcse_alloc (unsigned long size
)
939 return obstack_alloc (&gcse_obstack
, size
);
942 /* Allocate memory for the cuid mapping array,
943 and reg/memory set tracking tables.
945 This is called at the start of each pass. */
948 alloc_gcse_mem (rtx f
)
953 /* Find the largest UID and create a mapping from UIDs to CUIDs.
954 CUIDs are like UIDs except they increase monotonically, have no gaps,
955 and only apply to real insns. */
957 max_uid
= get_max_uid ();
958 uid_cuid
= gcalloc (max_uid
+ 1, sizeof (int));
959 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
962 uid_cuid
[INSN_UID (insn
)] = i
++;
964 uid_cuid
[INSN_UID (insn
)] = i
;
967 /* Create a table mapping cuids to insns. */
970 cuid_insn
= gcalloc (max_cuid
+ 1, sizeof (rtx
));
971 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
973 CUID_INSN (i
++) = insn
;
975 /* Allocate vars to track sets of regs. */
976 reg_set_bitmap
= BITMAP_XMALLOC ();
978 /* Allocate vars to track sets of regs, memory per block. */
979 reg_set_in_block
= sbitmap_vector_alloc (last_basic_block
, max_gcse_regno
);
980 /* Allocate array to keep a list of insns which modify memory in each
982 modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
983 canon_modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
984 modify_mem_list_set
= BITMAP_XMALLOC ();
985 canon_modify_mem_list_set
= BITMAP_XMALLOC ();
988 /* Free memory allocated by alloc_gcse_mem. */
996 BITMAP_XFREE (reg_set_bitmap
);
998 sbitmap_vector_free (reg_set_in_block
);
999 free_modify_mem_tables ();
1000 BITMAP_XFREE (modify_mem_list_set
);
1001 BITMAP_XFREE (canon_modify_mem_list_set
);
1004 /* Compute the local properties of each recorded expression.
1006 Local properties are those that are defined by the block, irrespective of
1009 An expression is transparent in a block if its operands are not modified
1012 An expression is computed (locally available) in a block if it is computed
1013 at least once and expression would contain the same value if the
1014 computation was moved to the end of the block.
1016 An expression is locally anticipatable in a block if it is computed at
1017 least once and expression would contain the same value if the computation
1018 was moved to the beginning of the block.
1020 We call this routine for cprop, pre and code hoisting. They all compute
1021 basically the same information and thus can easily share this code.
1023 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1024 properties. If NULL, then it is not necessary to compute or record that
1025 particular property.
1027 TABLE controls which hash table to look at. If it is set hash table,
1028 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1032 compute_local_properties (sbitmap
*transp
, sbitmap
*comp
, sbitmap
*antloc
,
1033 struct hash_table
*table
)
1037 /* Initialize any bitmaps that were passed in. */
1041 sbitmap_vector_zero (transp
, last_basic_block
);
1043 sbitmap_vector_ones (transp
, last_basic_block
);
1047 sbitmap_vector_zero (comp
, last_basic_block
);
1049 sbitmap_vector_zero (antloc
, last_basic_block
);
1051 for (i
= 0; i
< table
->size
; i
++)
1055 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1057 int indx
= expr
->bitmap_index
;
1060 /* The expression is transparent in this block if it is not killed.
1061 We start by assuming all are transparent [none are killed], and
1062 then reset the bits for those that are. */
1064 compute_transp (expr
->expr
, indx
, transp
, table
->set_p
);
1066 /* The occurrences recorded in antic_occr are exactly those that
1067 we want to set to nonzero in ANTLOC. */
1069 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
1071 SET_BIT (antloc
[BLOCK_NUM (occr
->insn
)], indx
);
1073 /* While we're scanning the table, this is a good place to
1075 occr
->deleted_p
= 0;
1078 /* The occurrences recorded in avail_occr are exactly those that
1079 we want to set to nonzero in COMP. */
1081 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
1083 SET_BIT (comp
[BLOCK_NUM (occr
->insn
)], indx
);
1085 /* While we're scanning the table, this is a good place to
1090 /* While we're scanning the table, this is a good place to
1092 expr
->reaching_reg
= 0;
1097 /* Register set information.
1099 `reg_set_table' records where each register is set or otherwise
1102 static struct obstack reg_set_obstack
;
1105 alloc_reg_set_mem (int n_regs
)
1107 reg_set_table_size
= n_regs
+ REG_SET_TABLE_SLOP
;
1108 reg_set_table
= gcalloc (reg_set_table_size
, sizeof (struct reg_set
*));
1110 gcc_obstack_init (®_set_obstack
);
1114 free_reg_set_mem (void)
1116 free (reg_set_table
);
1117 obstack_free (®_set_obstack
, NULL
);
1120 /* An OLD_INSN that used to set REGNO was replaced by NEW_INSN.
1121 Update the corresponding `reg_set_table' entry accordingly.
1122 We assume that NEW_INSN is not already recorded in reg_set_table[regno]. */
1125 replace_one_set (int regno
, rtx old_insn
, rtx new_insn
)
1127 struct reg_set
*reg_info
;
1128 if (regno
>= reg_set_table_size
)
1130 for (reg_info
= reg_set_table
[regno
]; reg_info
; reg_info
= reg_info
->next
)
1131 if (reg_info
->insn
== old_insn
)
1133 reg_info
->insn
= new_insn
;
1138 /* Record REGNO in the reg_set table. */
1141 record_one_set (int regno
, rtx insn
)
1143 /* Allocate a new reg_set element and link it onto the list. */
1144 struct reg_set
*new_reg_info
;
1146 /* If the table isn't big enough, enlarge it. */
1147 if (regno
>= reg_set_table_size
)
1149 int new_size
= regno
+ REG_SET_TABLE_SLOP
;
1151 reg_set_table
= grealloc (reg_set_table
,
1152 new_size
* sizeof (struct reg_set
*));
1153 memset (reg_set_table
+ reg_set_table_size
, 0,
1154 (new_size
- reg_set_table_size
) * sizeof (struct reg_set
*));
1155 reg_set_table_size
= new_size
;
1158 new_reg_info
= obstack_alloc (®_set_obstack
, sizeof (struct reg_set
));
1159 bytes_used
+= sizeof (struct reg_set
);
1160 new_reg_info
->insn
= insn
;
1161 new_reg_info
->next
= reg_set_table
[regno
];
1162 reg_set_table
[regno
] = new_reg_info
;
1165 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1166 an insn. The DATA is really the instruction in which the SET is
1170 record_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
, void *data
)
1172 rtx record_set_insn
= (rtx
) data
;
1174 if (REG_P (dest
) && REGNO (dest
) >= FIRST_PSEUDO_REGISTER
)
1175 record_one_set (REGNO (dest
), record_set_insn
);
1178 /* Scan the function and record each set of each pseudo-register.
1180 This is called once, at the start of the gcse pass. See the comments for
1181 `reg_set_table' for further documentation. */
1184 compute_sets (rtx f
)
1188 for (insn
= f
; insn
!= 0; insn
= NEXT_INSN (insn
))
1190 note_stores (PATTERN (insn
), record_set_info
, insn
);
1193 /* Hash table support. */
1195 struct reg_avail_info
1197 basic_block last_bb
;
1202 static struct reg_avail_info
*reg_avail_info
;
1203 static basic_block current_bb
;
1206 /* See whether X, the source of a set, is something we want to consider for
1210 want_to_gcse_p (rtx x
)
1212 switch (GET_CODE (x
))
1223 return can_assign_to_reg_p (x
);
1227 /* Used internally by can_assign_to_reg_p. */
1229 static GTY(()) rtx test_insn
;
1231 /* Return true if we can assign X to a pseudo register. */
1234 can_assign_to_reg_p (rtx x
)
1236 int num_clobbers
= 0;
1239 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1240 if (general_operand (x
, GET_MODE (x
)))
1242 else if (GET_MODE (x
) == VOIDmode
)
1245 /* Otherwise, check if we can make a valid insn from it. First initialize
1246 our test insn if we haven't already. */
1250 = make_insn_raw (gen_rtx_SET (VOIDmode
,
1251 gen_rtx_REG (word_mode
,
1252 FIRST_PSEUDO_REGISTER
* 2),
1254 NEXT_INSN (test_insn
) = PREV_INSN (test_insn
) = 0;
1257 /* Now make an insn like the one we would make when GCSE'ing and see if
1259 PUT_MODE (SET_DEST (PATTERN (test_insn
)), GET_MODE (x
));
1260 SET_SRC (PATTERN (test_insn
)) = x
;
1261 return ((icode
= recog (PATTERN (test_insn
), test_insn
, &num_clobbers
)) >= 0
1262 && (num_clobbers
== 0 || ! added_clobbers_hard_reg_p (icode
)));
1265 /* Return nonzero if the operands of expression X are unchanged from the
1266 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1267 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1270 oprs_unchanged_p (rtx x
, rtx insn
, int avail_p
)
1279 code
= GET_CODE (x
);
1284 struct reg_avail_info
*info
= ®_avail_info
[REGNO (x
)];
1286 if (info
->last_bb
!= current_bb
)
1289 return info
->last_set
< INSN_CUID (insn
);
1291 return info
->first_set
>= INSN_CUID (insn
);
1295 if (load_killed_in_block_p (current_bb
, INSN_CUID (insn
),
1299 return oprs_unchanged_p (XEXP (x
, 0), insn
, avail_p
);
1325 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1329 /* If we are about to do the last recursive call needed at this
1330 level, change it into iteration. This function is called enough
1333 return oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
);
1335 else if (! oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
))
1338 else if (fmt
[i
] == 'E')
1339 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1340 if (! oprs_unchanged_p (XVECEXP (x
, i
, j
), insn
, avail_p
))
1347 /* Used for communication between mems_conflict_for_gcse_p and
1348 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1349 conflict between two memory references. */
1350 static int gcse_mems_conflict_p
;
1352 /* Used for communication between mems_conflict_for_gcse_p and
1353 load_killed_in_block_p. A memory reference for a load instruction,
1354 mems_conflict_for_gcse_p will see if a memory store conflicts with
1355 this memory load. */
1356 static rtx gcse_mem_operand
;
1358 /* DEST is the output of an instruction. If it is a memory reference, and
1359 possibly conflicts with the load found in gcse_mem_operand, then set
1360 gcse_mems_conflict_p to a nonzero value. */
1363 mems_conflict_for_gcse_p (rtx dest
, rtx setter ATTRIBUTE_UNUSED
,
1364 void *data ATTRIBUTE_UNUSED
)
1366 while (GET_CODE (dest
) == SUBREG
1367 || GET_CODE (dest
) == ZERO_EXTRACT
1368 || GET_CODE (dest
) == SIGN_EXTRACT
1369 || GET_CODE (dest
) == STRICT_LOW_PART
)
1370 dest
= XEXP (dest
, 0);
1372 /* If DEST is not a MEM, then it will not conflict with the load. Note
1373 that function calls are assumed to clobber memory, but are handled
1378 /* If we are setting a MEM in our list of specially recognized MEMs,
1379 don't mark as killed this time. */
1381 if (expr_equiv_p (dest
, gcse_mem_operand
) && pre_ldst_mems
!= NULL
)
1383 if (!find_rtx_in_ldst (dest
))
1384 gcse_mems_conflict_p
= 1;
1388 if (true_dependence (dest
, GET_MODE (dest
), gcse_mem_operand
,
1390 gcse_mems_conflict_p
= 1;
1393 /* Return nonzero if the expression in X (a memory reference) is killed
1394 in block BB before or after the insn with the CUID in UID_LIMIT.
1395 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1398 To check the entire block, set UID_LIMIT to max_uid + 1 and
1402 load_killed_in_block_p (basic_block bb
, int uid_limit
, rtx x
, int avail_p
)
1404 rtx list_entry
= modify_mem_list
[bb
->index
];
1408 /* Ignore entries in the list that do not apply. */
1410 && INSN_CUID (XEXP (list_entry
, 0)) < uid_limit
)
1412 && INSN_CUID (XEXP (list_entry
, 0)) > uid_limit
))
1414 list_entry
= XEXP (list_entry
, 1);
1418 setter
= XEXP (list_entry
, 0);
1420 /* If SETTER is a call everything is clobbered. Note that calls
1421 to pure functions are never put on the list, so we need not
1422 worry about them. */
1423 if (CALL_P (setter
))
1426 /* SETTER must be an INSN of some kind that sets memory. Call
1427 note_stores to examine each hunk of memory that is modified.
1429 The note_stores interface is pretty limited, so we have to
1430 communicate via global variables. Yuk. */
1431 gcse_mem_operand
= x
;
1432 gcse_mems_conflict_p
= 0;
1433 note_stores (PATTERN (setter
), mems_conflict_for_gcse_p
, NULL
);
1434 if (gcse_mems_conflict_p
)
1436 list_entry
= XEXP (list_entry
, 1);
1441 /* Return nonzero if the operands of expression X are unchanged from
1442 the start of INSN's basic block up to but not including INSN. */
1445 oprs_anticipatable_p (rtx x
, rtx insn
)
1447 return oprs_unchanged_p (x
, insn
, 0);
1450 /* Return nonzero if the operands of expression X are unchanged from
1451 INSN to the end of INSN's basic block. */
1454 oprs_available_p (rtx x
, rtx insn
)
1456 return oprs_unchanged_p (x
, insn
, 1);
1459 /* Hash expression X.
1461 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1462 indicating if a volatile operand is found or if the expression contains
1463 something we don't want to insert in the table. HASH_TABLE_SIZE is
1464 the current size of the hash table to be probed. */
1467 hash_expr (rtx x
, enum machine_mode mode
, int *do_not_record_p
,
1468 int hash_table_size
)
1472 *do_not_record_p
= 0;
1474 hash
= hash_rtx (x
, mode
, do_not_record_p
,
1475 NULL
, /*have_reg_qty=*/false);
1476 return hash
% hash_table_size
;
1479 /* Hash a set of register REGNO.
1481 Sets are hashed on the register that is set. This simplifies the PRE copy
1484 ??? May need to make things more elaborate. Later, as necessary. */
1487 hash_set (int regno
, int hash_table_size
)
1492 return hash
% hash_table_size
;
1495 /* Return nonzero if exp1 is equivalent to exp2. */
1498 expr_equiv_p (rtx x
, rtx y
)
1500 return exp_equiv_p (x
, y
, 0, true);
1503 /* Insert expression X in INSN in the hash TABLE.
1504 If it is already present, record it as the last occurrence in INSN's
1507 MODE is the mode of the value X is being stored into.
1508 It is only used if X is a CONST_INT.
1510 ANTIC_P is nonzero if X is an anticipatable expression.
1511 AVAIL_P is nonzero if X is an available expression. */
1514 insert_expr_in_table (rtx x
, enum machine_mode mode
, rtx insn
, int antic_p
,
1515 int avail_p
, struct hash_table
*table
)
1517 int found
, do_not_record_p
;
1519 struct expr
*cur_expr
, *last_expr
= NULL
;
1520 struct occr
*antic_occr
, *avail_occr
;
1521 struct occr
*last_occr
= NULL
;
1523 hash
= hash_expr (x
, mode
, &do_not_record_p
, table
->size
);
1525 /* Do not insert expression in table if it contains volatile operands,
1526 or if hash_expr determines the expression is something we don't want
1527 to or can't handle. */
1528 if (do_not_record_p
)
1531 cur_expr
= table
->table
[hash
];
1534 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1536 /* If the expression isn't found, save a pointer to the end of
1538 last_expr
= cur_expr
;
1539 cur_expr
= cur_expr
->next_same_hash
;
1544 cur_expr
= gcse_alloc (sizeof (struct expr
));
1545 bytes_used
+= sizeof (struct expr
);
1546 if (table
->table
[hash
] == NULL
)
1547 /* This is the first pattern that hashed to this index. */
1548 table
->table
[hash
] = cur_expr
;
1550 /* Add EXPR to end of this hash chain. */
1551 last_expr
->next_same_hash
= cur_expr
;
1553 /* Set the fields of the expr element. */
1555 cur_expr
->bitmap_index
= table
->n_elems
++;
1556 cur_expr
->next_same_hash
= NULL
;
1557 cur_expr
->antic_occr
= NULL
;
1558 cur_expr
->avail_occr
= NULL
;
1561 /* Now record the occurrence(s). */
1564 antic_occr
= cur_expr
->antic_occr
;
1566 /* Search for another occurrence in the same basic block. */
1567 while (antic_occr
&& BLOCK_NUM (antic_occr
->insn
) != BLOCK_NUM (insn
))
1569 /* If an occurrence isn't found, save a pointer to the end of
1571 last_occr
= antic_occr
;
1572 antic_occr
= antic_occr
->next
;
1576 /* Found another instance of the expression in the same basic block.
1577 Prefer the currently recorded one. We want the first one in the
1578 block and the block is scanned from start to end. */
1579 ; /* nothing to do */
1582 /* First occurrence of this expression in this basic block. */
1583 antic_occr
= gcse_alloc (sizeof (struct occr
));
1584 bytes_used
+= sizeof (struct occr
);
1585 /* First occurrence of this expression in any block? */
1586 if (cur_expr
->antic_occr
== NULL
)
1587 cur_expr
->antic_occr
= antic_occr
;
1589 last_occr
->next
= antic_occr
;
1591 antic_occr
->insn
= insn
;
1592 antic_occr
->next
= NULL
;
1593 antic_occr
->deleted_p
= 0;
1599 avail_occr
= cur_expr
->avail_occr
;
1601 /* Search for another occurrence in the same basic block. */
1602 while (avail_occr
&& BLOCK_NUM (avail_occr
->insn
) != BLOCK_NUM (insn
))
1604 /* If an occurrence isn't found, save a pointer to the end of
1606 last_occr
= avail_occr
;
1607 avail_occr
= avail_occr
->next
;
1611 /* Found another instance of the expression in the same basic block.
1612 Prefer this occurrence to the currently recorded one. We want
1613 the last one in the block and the block is scanned from start
1615 avail_occr
->insn
= insn
;
1618 /* First occurrence of this expression in this basic block. */
1619 avail_occr
= gcse_alloc (sizeof (struct occr
));
1620 bytes_used
+= sizeof (struct occr
);
1622 /* First occurrence of this expression in any block? */
1623 if (cur_expr
->avail_occr
== NULL
)
1624 cur_expr
->avail_occr
= avail_occr
;
1626 last_occr
->next
= avail_occr
;
1628 avail_occr
->insn
= insn
;
1629 avail_occr
->next
= NULL
;
1630 avail_occr
->deleted_p
= 0;
1635 /* Insert pattern X in INSN in the hash table.
1636 X is a SET of a reg to either another reg or a constant.
1637 If it is already present, record it as the last occurrence in INSN's
1641 insert_set_in_table (rtx x
, rtx insn
, struct hash_table
*table
)
1645 struct expr
*cur_expr
, *last_expr
= NULL
;
1646 struct occr
*cur_occr
, *last_occr
= NULL
;
1648 gcc_assert (GET_CODE (x
) == SET
&& REG_P (SET_DEST (x
)));
1650 hash
= hash_set (REGNO (SET_DEST (x
)), table
->size
);
1652 cur_expr
= table
->table
[hash
];
1655 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1657 /* If the expression isn't found, save a pointer to the end of
1659 last_expr
= cur_expr
;
1660 cur_expr
= cur_expr
->next_same_hash
;
1665 cur_expr
= gcse_alloc (sizeof (struct expr
));
1666 bytes_used
+= sizeof (struct expr
);
1667 if (table
->table
[hash
] == NULL
)
1668 /* This is the first pattern that hashed to this index. */
1669 table
->table
[hash
] = cur_expr
;
1671 /* Add EXPR to end of this hash chain. */
1672 last_expr
->next_same_hash
= cur_expr
;
1674 /* Set the fields of the expr element.
1675 We must copy X because it can be modified when copy propagation is
1676 performed on its operands. */
1677 cur_expr
->expr
= copy_rtx (x
);
1678 cur_expr
->bitmap_index
= table
->n_elems
++;
1679 cur_expr
->next_same_hash
= NULL
;
1680 cur_expr
->antic_occr
= NULL
;
1681 cur_expr
->avail_occr
= NULL
;
1684 /* Now record the occurrence. */
1685 cur_occr
= cur_expr
->avail_occr
;
1687 /* Search for another occurrence in the same basic block. */
1688 while (cur_occr
&& BLOCK_NUM (cur_occr
->insn
) != BLOCK_NUM (insn
))
1690 /* If an occurrence isn't found, save a pointer to the end of
1692 last_occr
= cur_occr
;
1693 cur_occr
= cur_occr
->next
;
1697 /* Found another instance of the expression in the same basic block.
1698 Prefer this occurrence to the currently recorded one. We want the
1699 last one in the block and the block is scanned from start to end. */
1700 cur_occr
->insn
= insn
;
1703 /* First occurrence of this expression in this basic block. */
1704 cur_occr
= gcse_alloc (sizeof (struct occr
));
1705 bytes_used
+= sizeof (struct occr
);
1707 /* First occurrence of this expression in any block? */
1708 if (cur_expr
->avail_occr
== NULL
)
1709 cur_expr
->avail_occr
= cur_occr
;
1711 last_occr
->next
= cur_occr
;
1713 cur_occr
->insn
= insn
;
1714 cur_occr
->next
= NULL
;
1715 cur_occr
->deleted_p
= 0;
1719 /* Determine whether the rtx X should be treated as a constant for
1720 the purposes of GCSE's constant propagation. */
1723 gcse_constant_p (rtx x
)
1725 /* Consider a COMPARE of two integers constant. */
1726 if (GET_CODE (x
) == COMPARE
1727 && GET_CODE (XEXP (x
, 0)) == CONST_INT
1728 && GET_CODE (XEXP (x
, 1)) == CONST_INT
)
1731 /* Consider a COMPARE of the same registers is a constant
1732 if they are not floating point registers. */
1733 if (GET_CODE(x
) == COMPARE
1734 && REG_P (XEXP (x
, 0)) && REG_P (XEXP (x
, 1))
1735 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (x
, 1))
1736 && ! FLOAT_MODE_P (GET_MODE (XEXP (x
, 0)))
1737 && ! FLOAT_MODE_P (GET_MODE (XEXP (x
, 1))))
1740 return CONSTANT_P (x
);
1743 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
1747 hash_scan_set (rtx pat
, rtx insn
, struct hash_table
*table
)
1749 rtx src
= SET_SRC (pat
);
1750 rtx dest
= SET_DEST (pat
);
1753 if (GET_CODE (src
) == CALL
)
1754 hash_scan_call (src
, insn
, table
);
1756 else if (REG_P (dest
))
1758 unsigned int regno
= REGNO (dest
);
1761 /* If this is a single set and we are doing constant propagation,
1762 see if a REG_NOTE shows this equivalent to a constant. */
1763 if (table
->set_p
&& (note
= find_reg_equal_equiv_note (insn
)) != 0
1764 && gcse_constant_p (XEXP (note
, 0)))
1765 src
= XEXP (note
, 0), pat
= gen_rtx_SET (VOIDmode
, dest
, src
);
1767 /* Only record sets of pseudo-regs in the hash table. */
1769 && regno
>= FIRST_PSEUDO_REGISTER
1770 /* Don't GCSE something if we can't do a reg/reg copy. */
1771 && can_copy_p (GET_MODE (dest
))
1772 /* GCSE commonly inserts instruction after the insn. We can't
1773 do that easily for EH_REGION notes so disable GCSE on these
1775 && !find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
1776 /* Is SET_SRC something we want to gcse? */
1777 && want_to_gcse_p (src
)
1778 /* Don't CSE a nop. */
1779 && ! set_noop_p (pat
)
1780 /* Don't GCSE if it has attached REG_EQUIV note.
1781 At this point this only function parameters should have
1782 REG_EQUIV notes and if the argument slot is used somewhere
1783 explicitly, it means address of parameter has been taken,
1784 so we should not extend the lifetime of the pseudo. */
1785 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
1786 || ! MEM_P (XEXP (note
, 0))))
1788 /* An expression is not anticipatable if its operands are
1789 modified before this insn or if this is not the only SET in
1791 int antic_p
= oprs_anticipatable_p (src
, insn
) && single_set (insn
);
1792 /* An expression is not available if its operands are
1793 subsequently modified, including this insn. It's also not
1794 available if this is a branch, because we can't insert
1795 a set after the branch. */
1796 int avail_p
= (oprs_available_p (src
, insn
)
1797 && ! JUMP_P (insn
));
1799 insert_expr_in_table (src
, GET_MODE (dest
), insn
, antic_p
, avail_p
, table
);
1802 /* Record sets for constant/copy propagation. */
1803 else if (table
->set_p
1804 && regno
>= FIRST_PSEUDO_REGISTER
1806 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
1807 && can_copy_p (GET_MODE (dest
))
1808 && REGNO (src
) != regno
)
1809 || gcse_constant_p (src
))
1810 /* A copy is not available if its src or dest is subsequently
1811 modified. Here we want to search from INSN+1 on, but
1812 oprs_available_p searches from INSN on. */
1813 && (insn
== BB_END (BLOCK_FOR_INSN (insn
))
1814 || ((tmp
= next_nonnote_insn (insn
)) != NULL_RTX
1815 && oprs_available_p (pat
, tmp
))))
1816 insert_set_in_table (pat
, insn
, table
);
1818 /* In case of store we want to consider the memory value as available in
1819 the REG stored in that memory. This makes it possible to remove
1820 redundant loads from due to stores to the same location. */
1821 else if (flag_gcse_las
&& REG_P (src
) && MEM_P (dest
))
1823 unsigned int regno
= REGNO (src
);
1825 /* Do not do this for constant/copy propagation. */
1827 /* Only record sets of pseudo-regs in the hash table. */
1828 && regno
>= FIRST_PSEUDO_REGISTER
1829 /* Don't GCSE something if we can't do a reg/reg copy. */
1830 && can_copy_p (GET_MODE (src
))
1831 /* GCSE commonly inserts instruction after the insn. We can't
1832 do that easily for EH_REGION notes so disable GCSE on these
1834 && ! find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
1835 /* Is SET_DEST something we want to gcse? */
1836 && want_to_gcse_p (dest
)
1837 /* Don't CSE a nop. */
1838 && ! set_noop_p (pat
)
1839 /* Don't GCSE if it has attached REG_EQUIV note.
1840 At this point this only function parameters should have
1841 REG_EQUIV notes and if the argument slot is used somewhere
1842 explicitly, it means address of parameter has been taken,
1843 so we should not extend the lifetime of the pseudo. */
1844 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
1845 || ! MEM_P (XEXP (note
, 0))))
1847 /* Stores are never anticipatable. */
1849 /* An expression is not available if its operands are
1850 subsequently modified, including this insn. It's also not
1851 available if this is a branch, because we can't insert
1852 a set after the branch. */
1853 int avail_p
= oprs_available_p (dest
, insn
)
1856 /* Record the memory expression (DEST) in the hash table. */
1857 insert_expr_in_table (dest
, GET_MODE (dest
), insn
,
1858 antic_p
, avail_p
, table
);
1864 hash_scan_clobber (rtx x ATTRIBUTE_UNUSED
, rtx insn ATTRIBUTE_UNUSED
,
1865 struct hash_table
*table ATTRIBUTE_UNUSED
)
1867 /* Currently nothing to do. */
1871 hash_scan_call (rtx x ATTRIBUTE_UNUSED
, rtx insn ATTRIBUTE_UNUSED
,
1872 struct hash_table
*table ATTRIBUTE_UNUSED
)
1874 /* Currently nothing to do. */
1877 /* Process INSN and add hash table entries as appropriate.
1879 Only available expressions that set a single pseudo-reg are recorded.
1881 Single sets in a PARALLEL could be handled, but it's an extra complication
1882 that isn't dealt with right now. The trick is handling the CLOBBERs that
1883 are also in the PARALLEL. Later.
1885 If SET_P is nonzero, this is for the assignment hash table,
1886 otherwise it is for the expression hash table.
1887 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
1888 not record any expressions. */
1891 hash_scan_insn (rtx insn
, struct hash_table
*table
, int in_libcall_block
)
1893 rtx pat
= PATTERN (insn
);
1896 if (in_libcall_block
)
1899 /* Pick out the sets of INSN and for other forms of instructions record
1900 what's been modified. */
1902 if (GET_CODE (pat
) == SET
)
1903 hash_scan_set (pat
, insn
, table
);
1904 else if (GET_CODE (pat
) == PARALLEL
)
1905 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
1907 rtx x
= XVECEXP (pat
, 0, i
);
1909 if (GET_CODE (x
) == SET
)
1910 hash_scan_set (x
, insn
, table
);
1911 else if (GET_CODE (x
) == CLOBBER
)
1912 hash_scan_clobber (x
, insn
, table
);
1913 else if (GET_CODE (x
) == CALL
)
1914 hash_scan_call (x
, insn
, table
);
1917 else if (GET_CODE (pat
) == CLOBBER
)
1918 hash_scan_clobber (pat
, insn
, table
);
1919 else if (GET_CODE (pat
) == CALL
)
1920 hash_scan_call (pat
, insn
, table
);
1924 dump_hash_table (FILE *file
, const char *name
, struct hash_table
*table
)
1927 /* Flattened out table, so it's printed in proper order. */
1928 struct expr
**flat_table
;
1929 unsigned int *hash_val
;
1932 flat_table
= xcalloc (table
->n_elems
, sizeof (struct expr
*));
1933 hash_val
= xmalloc (table
->n_elems
* sizeof (unsigned int));
1935 for (i
= 0; i
< (int) table
->size
; i
++)
1936 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1938 flat_table
[expr
->bitmap_index
] = expr
;
1939 hash_val
[expr
->bitmap_index
] = i
;
1942 fprintf (file
, "%s hash table (%d buckets, %d entries)\n",
1943 name
, table
->size
, table
->n_elems
);
1945 for (i
= 0; i
< (int) table
->n_elems
; i
++)
1946 if (flat_table
[i
] != 0)
1948 expr
= flat_table
[i
];
1949 fprintf (file
, "Index %d (hash value %d)\n ",
1950 expr
->bitmap_index
, hash_val
[i
]);
1951 print_rtl (file
, expr
->expr
);
1952 fprintf (file
, "\n");
1955 fprintf (file
, "\n");
1961 /* Record register first/last/block set information for REGNO in INSN.
1963 first_set records the first place in the block where the register
1964 is set and is used to compute "anticipatability".
1966 last_set records the last place in the block where the register
1967 is set and is used to compute "availability".
1969 last_bb records the block for which first_set and last_set are
1970 valid, as a quick test to invalidate them.
1972 reg_set_in_block records whether the register is set in the block
1973 and is used to compute "transparency". */
1976 record_last_reg_set_info (rtx insn
, int regno
)
1978 struct reg_avail_info
*info
= ®_avail_info
[regno
];
1979 int cuid
= INSN_CUID (insn
);
1981 info
->last_set
= cuid
;
1982 if (info
->last_bb
!= current_bb
)
1984 info
->last_bb
= current_bb
;
1985 info
->first_set
= cuid
;
1986 SET_BIT (reg_set_in_block
[current_bb
->index
], regno
);
1991 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
1992 Note we store a pair of elements in the list, so they have to be
1993 taken off pairwise. */
1996 canon_list_insert (rtx dest ATTRIBUTE_UNUSED
, rtx unused1 ATTRIBUTE_UNUSED
,
1999 rtx dest_addr
, insn
;
2002 while (GET_CODE (dest
) == SUBREG
2003 || GET_CODE (dest
) == ZERO_EXTRACT
2004 || GET_CODE (dest
) == SIGN_EXTRACT
2005 || GET_CODE (dest
) == STRICT_LOW_PART
)
2006 dest
= XEXP (dest
, 0);
2008 /* If DEST is not a MEM, then it will not conflict with a load. Note
2009 that function calls are assumed to clobber memory, but are handled
2015 dest_addr
= get_addr (XEXP (dest
, 0));
2016 dest_addr
= canon_rtx (dest_addr
);
2017 insn
= (rtx
) v_insn
;
2018 bb
= BLOCK_NUM (insn
);
2020 canon_modify_mem_list
[bb
] =
2021 alloc_EXPR_LIST (VOIDmode
, dest_addr
, canon_modify_mem_list
[bb
]);
2022 canon_modify_mem_list
[bb
] =
2023 alloc_EXPR_LIST (VOIDmode
, dest
, canon_modify_mem_list
[bb
]);
2024 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2027 /* Record memory modification information for INSN. We do not actually care
2028 about the memory location(s) that are set, or even how they are set (consider
2029 a CALL_INSN). We merely need to record which insns modify memory. */
2032 record_last_mem_set_info (rtx insn
)
2034 int bb
= BLOCK_NUM (insn
);
2036 /* load_killed_in_block_p will handle the case of calls clobbering
2038 modify_mem_list
[bb
] = alloc_INSN_LIST (insn
, modify_mem_list
[bb
]);
2039 bitmap_set_bit (modify_mem_list_set
, bb
);
2043 /* Note that traversals of this loop (other than for free-ing)
2044 will break after encountering a CALL_INSN. So, there's no
2045 need to insert a pair of items, as canon_list_insert does. */
2046 canon_modify_mem_list
[bb
] =
2047 alloc_INSN_LIST (insn
, canon_modify_mem_list
[bb
]);
2048 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2051 note_stores (PATTERN (insn
), canon_list_insert
, (void*) insn
);
2054 /* Called from compute_hash_table via note_stores to handle one
2055 SET or CLOBBER in an insn. DATA is really the instruction in which
2056 the SET is taking place. */
2059 record_last_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
, void *data
)
2061 rtx last_set_insn
= (rtx
) data
;
2063 if (GET_CODE (dest
) == SUBREG
)
2064 dest
= SUBREG_REG (dest
);
2067 record_last_reg_set_info (last_set_insn
, REGNO (dest
));
2068 else if (MEM_P (dest
)
2069 /* Ignore pushes, they clobber nothing. */
2070 && ! push_operand (dest
, GET_MODE (dest
)))
2071 record_last_mem_set_info (last_set_insn
);
2074 /* Top level function to create an expression or assignment hash table.
2076 Expression entries are placed in the hash table if
2077 - they are of the form (set (pseudo-reg) src),
2078 - src is something we want to perform GCSE on,
2079 - none of the operands are subsequently modified in the block
2081 Assignment entries are placed in the hash table if
2082 - they are of the form (set (pseudo-reg) src),
2083 - src is something we want to perform const/copy propagation on,
2084 - none of the operands or target are subsequently modified in the block
2086 Currently src must be a pseudo-reg or a const_int.
2088 TABLE is the table computed. */
2091 compute_hash_table_work (struct hash_table
*table
)
2095 /* While we compute the hash table we also compute a bit array of which
2096 registers are set in which blocks.
2097 ??? This isn't needed during const/copy propagation, but it's cheap to
2099 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
2101 /* re-Cache any INSN_LIST nodes we have allocated. */
2102 clear_modify_mem_tables ();
2103 /* Some working arrays used to track first and last set in each block. */
2104 reg_avail_info
= gmalloc (max_gcse_regno
* sizeof (struct reg_avail_info
));
2106 for (i
= 0; i
< max_gcse_regno
; ++i
)
2107 reg_avail_info
[i
].last_bb
= NULL
;
2109 FOR_EACH_BB (current_bb
)
2113 int in_libcall_block
;
2115 /* First pass over the instructions records information used to
2116 determine when registers and memory are first and last set.
2117 ??? hard-reg reg_set_in_block computation
2118 could be moved to compute_sets since they currently don't change. */
2120 for (insn
= BB_HEAD (current_bb
);
2121 insn
&& insn
!= NEXT_INSN (BB_END (current_bb
));
2122 insn
= NEXT_INSN (insn
))
2124 if (! INSN_P (insn
))
2129 bool clobbers_all
= false;
2130 #ifdef NON_SAVING_SETJMP
2131 if (NON_SAVING_SETJMP
2132 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
2133 clobbers_all
= true;
2136 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2138 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2139 record_last_reg_set_info (insn
, regno
);
2144 note_stores (PATTERN (insn
), record_last_set_info
, insn
);
2147 /* Insert implicit sets in the hash table. */
2149 && implicit_sets
[current_bb
->index
] != NULL_RTX
)
2150 hash_scan_set (implicit_sets
[current_bb
->index
],
2151 BB_HEAD (current_bb
), table
);
2153 /* The next pass builds the hash table. */
2155 for (insn
= BB_HEAD (current_bb
), in_libcall_block
= 0;
2156 insn
&& insn
!= NEXT_INSN (BB_END (current_bb
));
2157 insn
= NEXT_INSN (insn
))
2160 if (find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2161 in_libcall_block
= 1;
2162 else if (table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2163 in_libcall_block
= 0;
2164 hash_scan_insn (insn
, table
, in_libcall_block
);
2165 if (!table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2166 in_libcall_block
= 0;
2170 free (reg_avail_info
);
2171 reg_avail_info
= NULL
;
2174 /* Allocate space for the set/expr hash TABLE.
2175 N_INSNS is the number of instructions in the function.
2176 It is used to determine the number of buckets to use.
2177 SET_P determines whether set or expression table will
2181 alloc_hash_table (int n_insns
, struct hash_table
*table
, int set_p
)
2185 table
->size
= n_insns
/ 4;
2186 if (table
->size
< 11)
2189 /* Attempt to maintain efficient use of hash table.
2190 Making it an odd number is simplest for now.
2191 ??? Later take some measurements. */
2193 n
= table
->size
* sizeof (struct expr
*);
2194 table
->table
= gmalloc (n
);
2195 table
->set_p
= set_p
;
2198 /* Free things allocated by alloc_hash_table. */
2201 free_hash_table (struct hash_table
*table
)
2203 free (table
->table
);
2206 /* Compute the hash TABLE for doing copy/const propagation or
2207 expression hash table. */
2210 compute_hash_table (struct hash_table
*table
)
2212 /* Initialize count of number of entries in hash table. */
2214 memset (table
->table
, 0, table
->size
* sizeof (struct expr
*));
2216 compute_hash_table_work (table
);
2219 /* Expression tracking support. */
2221 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2222 table entry, or NULL if not found. */
2224 static struct expr
*
2225 lookup_set (unsigned int regno
, struct hash_table
*table
)
2227 unsigned int hash
= hash_set (regno
, table
->size
);
2230 expr
= table
->table
[hash
];
2232 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
)
2233 expr
= expr
->next_same_hash
;
2238 /* Return the next entry for REGNO in list EXPR. */
2240 static struct expr
*
2241 next_set (unsigned int regno
, struct expr
*expr
)
2244 expr
= expr
->next_same_hash
;
2245 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
);
2250 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2251 types may be mixed. */
2254 free_insn_expr_list_list (rtx
*listp
)
2258 for (list
= *listp
; list
; list
= next
)
2260 next
= XEXP (list
, 1);
2261 if (GET_CODE (list
) == EXPR_LIST
)
2262 free_EXPR_LIST_node (list
);
2264 free_INSN_LIST_node (list
);
2270 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2272 clear_modify_mem_tables (void)
2277 EXECUTE_IF_SET_IN_BITMAP (modify_mem_list_set
, 0, i
, bi
)
2279 free_INSN_LIST_list (modify_mem_list
+ i
);
2281 bitmap_clear (modify_mem_list_set
);
2283 EXECUTE_IF_SET_IN_BITMAP (canon_modify_mem_list_set
, 0, i
, bi
)
2285 free_insn_expr_list_list (canon_modify_mem_list
+ i
);
2287 bitmap_clear (canon_modify_mem_list_set
);
2290 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2293 free_modify_mem_tables (void)
2295 clear_modify_mem_tables ();
2296 free (modify_mem_list
);
2297 free (canon_modify_mem_list
);
2298 modify_mem_list
= 0;
2299 canon_modify_mem_list
= 0;
2302 /* Reset tables used to keep track of what's still available [since the
2303 start of the block]. */
2306 reset_opr_set_tables (void)
2308 /* Maintain a bitmap of which regs have been set since beginning of
2310 CLEAR_REG_SET (reg_set_bitmap
);
2312 /* Also keep a record of the last instruction to modify memory.
2313 For now this is very trivial, we only record whether any memory
2314 location has been modified. */
2315 clear_modify_mem_tables ();
2318 /* Return nonzero if the operands of X are not set before INSN in
2319 INSN's basic block. */
2322 oprs_not_set_p (rtx x
, rtx insn
)
2331 code
= GET_CODE (x
);
2347 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn
),
2348 INSN_CUID (insn
), x
, 0))
2351 return oprs_not_set_p (XEXP (x
, 0), insn
);
2354 return ! REGNO_REG_SET_P (reg_set_bitmap
, REGNO (x
));
2360 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2364 /* If we are about to do the last recursive call
2365 needed at this level, change it into iteration.
2366 This function is called enough to be worth it. */
2368 return oprs_not_set_p (XEXP (x
, i
), insn
);
2370 if (! oprs_not_set_p (XEXP (x
, i
), insn
))
2373 else if (fmt
[i
] == 'E')
2374 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2375 if (! oprs_not_set_p (XVECEXP (x
, i
, j
), insn
))
2382 /* Mark things set by a CALL. */
2385 mark_call (rtx insn
)
2387 if (! CONST_OR_PURE_CALL_P (insn
))
2388 record_last_mem_set_info (insn
);
2391 /* Mark things set by a SET. */
2394 mark_set (rtx pat
, rtx insn
)
2396 rtx dest
= SET_DEST (pat
);
2398 while (GET_CODE (dest
) == SUBREG
2399 || GET_CODE (dest
) == ZERO_EXTRACT
2400 || GET_CODE (dest
) == SIGN_EXTRACT
2401 || GET_CODE (dest
) == STRICT_LOW_PART
)
2402 dest
= XEXP (dest
, 0);
2405 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (dest
));
2406 else if (MEM_P (dest
))
2407 record_last_mem_set_info (insn
);
2409 if (GET_CODE (SET_SRC (pat
)) == CALL
)
2413 /* Record things set by a CLOBBER. */
2416 mark_clobber (rtx pat
, rtx insn
)
2418 rtx clob
= XEXP (pat
, 0);
2420 while (GET_CODE (clob
) == SUBREG
|| GET_CODE (clob
) == STRICT_LOW_PART
)
2421 clob
= XEXP (clob
, 0);
2424 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (clob
));
2426 record_last_mem_set_info (insn
);
2429 /* Record things set by INSN.
2430 This data is used by oprs_not_set_p. */
2433 mark_oprs_set (rtx insn
)
2435 rtx pat
= PATTERN (insn
);
2438 if (GET_CODE (pat
) == SET
)
2439 mark_set (pat
, insn
);
2440 else if (GET_CODE (pat
) == PARALLEL
)
2441 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2443 rtx x
= XVECEXP (pat
, 0, i
);
2445 if (GET_CODE (x
) == SET
)
2447 else if (GET_CODE (x
) == CLOBBER
)
2448 mark_clobber (x
, insn
);
2449 else if (GET_CODE (x
) == CALL
)
2453 else if (GET_CODE (pat
) == CLOBBER
)
2454 mark_clobber (pat
, insn
);
2455 else if (GET_CODE (pat
) == CALL
)
2460 /* Compute copy/constant propagation working variables. */
2462 /* Local properties of assignments. */
2463 static sbitmap
*cprop_pavloc
;
2464 static sbitmap
*cprop_absaltered
;
2466 /* Global properties of assignments (computed from the local properties). */
2467 static sbitmap
*cprop_avin
;
2468 static sbitmap
*cprop_avout
;
2470 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
2471 basic blocks. N_SETS is the number of sets. */
2474 alloc_cprop_mem (int n_blocks
, int n_sets
)
2476 cprop_pavloc
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2477 cprop_absaltered
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2479 cprop_avin
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2480 cprop_avout
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2483 /* Free vars used by copy/const propagation. */
2486 free_cprop_mem (void)
2488 sbitmap_vector_free (cprop_pavloc
);
2489 sbitmap_vector_free (cprop_absaltered
);
2490 sbitmap_vector_free (cprop_avin
);
2491 sbitmap_vector_free (cprop_avout
);
2494 /* For each block, compute whether X is transparent. X is either an
2495 expression or an assignment [though we don't care which, for this context
2496 an assignment is treated as an expression]. For each block where an
2497 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
2501 compute_transp (rtx x
, int indx
, sbitmap
*bmap
, int set_p
)
2509 /* repeat is used to turn tail-recursion into iteration since GCC
2510 can't do it when there's no return value. */
2516 code
= GET_CODE (x
);
2522 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
2525 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
2526 SET_BIT (bmap
[bb
->index
], indx
);
2530 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
2531 SET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
2536 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
2539 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
2540 RESET_BIT (bmap
[bb
->index
], indx
);
2544 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
2545 RESET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
2554 rtx list_entry
= canon_modify_mem_list
[bb
->index
];
2558 rtx dest
, dest_addr
;
2560 if (CALL_P (XEXP (list_entry
, 0)))
2563 SET_BIT (bmap
[bb
->index
], indx
);
2565 RESET_BIT (bmap
[bb
->index
], indx
);
2568 /* LIST_ENTRY must be an INSN of some kind that sets memory.
2569 Examine each hunk of memory that is modified. */
2571 dest
= XEXP (list_entry
, 0);
2572 list_entry
= XEXP (list_entry
, 1);
2573 dest_addr
= XEXP (list_entry
, 0);
2575 if (canon_true_dependence (dest
, GET_MODE (dest
), dest_addr
,
2576 x
, rtx_addr_varies_p
))
2579 SET_BIT (bmap
[bb
->index
], indx
);
2581 RESET_BIT (bmap
[bb
->index
], indx
);
2584 list_entry
= XEXP (list_entry
, 1);
2607 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2611 /* If we are about to do the last recursive call
2612 needed at this level, change it into iteration.
2613 This function is called enough to be worth it. */
2620 compute_transp (XEXP (x
, i
), indx
, bmap
, set_p
);
2622 else if (fmt
[i
] == 'E')
2623 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2624 compute_transp (XVECEXP (x
, i
, j
), indx
, bmap
, set_p
);
2628 /* Top level routine to do the dataflow analysis needed by copy/const
2632 compute_cprop_data (void)
2634 compute_local_properties (cprop_absaltered
, cprop_pavloc
, NULL
, &set_hash_table
);
2635 compute_available (cprop_pavloc
, cprop_absaltered
,
2636 cprop_avout
, cprop_avin
);
2639 /* Copy/constant propagation. */
2641 /* Maximum number of register uses in an insn that we handle. */
2644 /* Table of uses found in an insn.
2645 Allocated statically to avoid alloc/free complexity and overhead. */
2646 static struct reg_use reg_use_table
[MAX_USES
];
2648 /* Index into `reg_use_table' while building it. */
2649 static int reg_use_count
;
2651 /* Set up a list of register numbers used in INSN. The found uses are stored
2652 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
2653 and contains the number of uses in the table upon exit.
2655 ??? If a register appears multiple times we will record it multiple times.
2656 This doesn't hurt anything but it will slow things down. */
2659 find_used_regs (rtx
*xptr
, void *data ATTRIBUTE_UNUSED
)
2666 /* repeat is used to turn tail-recursion into iteration since GCC
2667 can't do it when there's no return value. */
2672 code
= GET_CODE (x
);
2675 if (reg_use_count
== MAX_USES
)
2678 reg_use_table
[reg_use_count
].reg_rtx
= x
;
2682 /* Recursively scan the operands of this expression. */
2684 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2688 /* If we are about to do the last recursive call
2689 needed at this level, change it into iteration.
2690 This function is called enough to be worth it. */
2697 find_used_regs (&XEXP (x
, i
), data
);
2699 else if (fmt
[i
] == 'E')
2700 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2701 find_used_regs (&XVECEXP (x
, i
, j
), data
);
2705 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
2706 Returns nonzero is successful. */
2709 try_replace_reg (rtx from
, rtx to
, rtx insn
)
2711 rtx note
= find_reg_equal_equiv_note (insn
);
2714 rtx set
= single_set (insn
);
2716 validate_replace_src_group (from
, to
, insn
);
2717 if (num_changes_pending () && apply_change_group ())
2720 /* Try to simplify SET_SRC if we have substituted a constant. */
2721 if (success
&& set
&& CONSTANT_P (to
))
2723 src
= simplify_rtx (SET_SRC (set
));
2726 validate_change (insn
, &SET_SRC (set
), src
, 0);
2729 /* If there is already a NOTE, update the expression in it with our
2732 XEXP (note
, 0) = simplify_replace_rtx (XEXP (note
, 0), from
, to
);
2734 if (!success
&& set
&& reg_mentioned_p (from
, SET_SRC (set
)))
2736 /* If above failed and this is a single set, try to simplify the source of
2737 the set given our substitution. We could perhaps try this for multiple
2738 SETs, but it probably won't buy us anything. */
2739 src
= simplify_replace_rtx (SET_SRC (set
), from
, to
);
2741 if (!rtx_equal_p (src
, SET_SRC (set
))
2742 && validate_change (insn
, &SET_SRC (set
), src
, 0))
2745 /* If we've failed to do replacement, have a single SET, don't already
2746 have a note, and have no special SET, add a REG_EQUAL note to not
2747 lose information. */
2748 if (!success
&& note
== 0 && set
!= 0
2749 && GET_CODE (XEXP (set
, 0)) != ZERO_EXTRACT
2750 && GET_CODE (XEXP (set
, 0)) != SIGN_EXTRACT
)
2751 note
= set_unique_reg_note (insn
, REG_EQUAL
, copy_rtx (src
));
2754 /* REG_EQUAL may get simplified into register.
2755 We don't allow that. Remove that note. This code ought
2756 not to happen, because previous code ought to synthesize
2757 reg-reg move, but be on the safe side. */
2758 if (note
&& REG_P (XEXP (note
, 0)))
2759 remove_note (insn
, note
);
2764 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
2765 NULL no such set is found. */
2767 static struct expr
*
2768 find_avail_set (int regno
, rtx insn
)
2770 /* SET1 contains the last set found that can be returned to the caller for
2771 use in a substitution. */
2772 struct expr
*set1
= 0;
2774 /* Loops are not possible here. To get a loop we would need two sets
2775 available at the start of the block containing INSN. i.e. we would
2776 need two sets like this available at the start of the block:
2778 (set (reg X) (reg Y))
2779 (set (reg Y) (reg X))
2781 This can not happen since the set of (reg Y) would have killed the
2782 set of (reg X) making it unavailable at the start of this block. */
2786 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
2788 /* Find a set that is available at the start of the block
2789 which contains INSN. */
2792 if (TEST_BIT (cprop_avin
[BLOCK_NUM (insn
)], set
->bitmap_index
))
2794 set
= next_set (regno
, set
);
2797 /* If no available set was found we've reached the end of the
2798 (possibly empty) copy chain. */
2802 gcc_assert (GET_CODE (set
->expr
) == SET
);
2804 src
= SET_SRC (set
->expr
);
2806 /* We know the set is available.
2807 Now check that SRC is ANTLOC (i.e. none of the source operands
2808 have changed since the start of the block).
2810 If the source operand changed, we may still use it for the next
2811 iteration of this loop, but we may not use it for substitutions. */
2813 if (gcse_constant_p (src
) || oprs_not_set_p (src
, insn
))
2816 /* If the source of the set is anything except a register, then
2817 we have reached the end of the copy chain. */
2821 /* Follow the copy chain, i.e. start another iteration of the loop
2822 and see if we have an available copy into SRC. */
2823 regno
= REGNO (src
);
2826 /* SET1 holds the last set that was available and anticipatable at
2831 /* Subroutine of cprop_insn that tries to propagate constants into
2832 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
2833 it is the instruction that immediately precedes JUMP, and must be a
2834 single SET of a register. FROM is what we will try to replace,
2835 SRC is the constant we will try to substitute for it. Returns nonzero
2836 if a change was made. */
2839 cprop_jump (basic_block bb
, rtx setcc
, rtx jump
, rtx from
, rtx src
)
2841 rtx
new, set_src
, note_src
;
2842 rtx set
= pc_set (jump
);
2843 rtx note
= find_reg_equal_equiv_note (jump
);
2847 note_src
= XEXP (note
, 0);
2848 if (GET_CODE (note_src
) == EXPR_LIST
)
2849 note_src
= NULL_RTX
;
2851 else note_src
= NULL_RTX
;
2853 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
2854 set_src
= note_src
? note_src
: SET_SRC (set
);
2856 /* First substitute the SETCC condition into the JUMP instruction,
2857 then substitute that given values into this expanded JUMP. */
2858 if (setcc
!= NULL_RTX
2859 && !modified_between_p (from
, setcc
, jump
)
2860 && !modified_between_p (src
, setcc
, jump
))
2863 rtx setcc_set
= single_set (setcc
);
2864 rtx setcc_note
= find_reg_equal_equiv_note (setcc
);
2865 setcc_src
= (setcc_note
&& GET_CODE (XEXP (setcc_note
, 0)) != EXPR_LIST
)
2866 ? XEXP (setcc_note
, 0) : SET_SRC (setcc_set
);
2867 set_src
= simplify_replace_rtx (set_src
, SET_DEST (setcc_set
),
2873 new = simplify_replace_rtx (set_src
, from
, src
);
2875 /* If no simplification can be made, then try the next register. */
2876 if (rtx_equal_p (new, SET_SRC (set
)))
2879 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
2884 /* Ensure the value computed inside the jump insn to be equivalent
2885 to one computed by setcc. */
2886 if (setcc
&& modified_in_p (new, setcc
))
2888 if (! validate_change (jump
, &SET_SRC (set
), new, 0))
2890 /* When (some) constants are not valid in a comparison, and there
2891 are two registers to be replaced by constants before the entire
2892 comparison can be folded into a constant, we need to keep
2893 intermediate information in REG_EQUAL notes. For targets with
2894 separate compare insns, such notes are added by try_replace_reg.
2895 When we have a combined compare-and-branch instruction, however,
2896 we need to attach a note to the branch itself to make this
2897 optimization work. */
2899 if (!rtx_equal_p (new, note_src
))
2900 set_unique_reg_note (jump
, REG_EQUAL
, copy_rtx (new));
2904 /* Remove REG_EQUAL note after simplification. */
2906 remove_note (jump
, note
);
2908 /* If this has turned into an unconditional jump,
2909 then put a barrier after it so that the unreachable
2910 code will be deleted. */
2911 if (GET_CODE (SET_SRC (set
)) == LABEL_REF
)
2912 emit_barrier_after (jump
);
2916 /* Delete the cc0 setter. */
2917 if (setcc
!= NULL
&& CC0_P (SET_DEST (single_set (setcc
))))
2918 delete_insn (setcc
);
2921 run_jump_opt_after_gcse
= 1;
2923 global_const_prop_count
++;
2924 if (gcse_file
!= NULL
)
2927 "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
2928 REGNO (from
), INSN_UID (jump
));
2929 print_rtl (gcse_file
, src
);
2930 fprintf (gcse_file
, "\n");
2932 purge_dead_edges (bb
);
2938 constprop_register (rtx insn
, rtx from
, rtx to
, int alter_jumps
)
2942 /* Check for reg or cc0 setting instructions followed by
2943 conditional branch instructions first. */
2945 && (sset
= single_set (insn
)) != NULL
2947 && any_condjump_p (NEXT_INSN (insn
)) && onlyjump_p (NEXT_INSN (insn
)))
2949 rtx dest
= SET_DEST (sset
);
2950 if ((REG_P (dest
) || CC0_P (dest
))
2951 && cprop_jump (BLOCK_FOR_INSN (insn
), insn
, NEXT_INSN (insn
), from
, to
))
2955 /* Handle normal insns next. */
2956 if (NONJUMP_INSN_P (insn
)
2957 && try_replace_reg (from
, to
, insn
))
2960 /* Try to propagate a CONST_INT into a conditional jump.
2961 We're pretty specific about what we will handle in this
2962 code, we can extend this as necessary over time.
2964 Right now the insn in question must look like
2965 (set (pc) (if_then_else ...)) */
2966 else if (alter_jumps
&& any_condjump_p (insn
) && onlyjump_p (insn
))
2967 return cprop_jump (BLOCK_FOR_INSN (insn
), NULL
, insn
, from
, to
);
2971 /* Perform constant and copy propagation on INSN.
2972 The result is nonzero if a change was made. */
2975 cprop_insn (rtx insn
, int alter_jumps
)
2977 struct reg_use
*reg_used
;
2985 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
2987 note
= find_reg_equal_equiv_note (insn
);
2989 /* We may win even when propagating constants into notes. */
2991 find_used_regs (&XEXP (note
, 0), NULL
);
2993 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
2994 reg_used
++, reg_use_count
--)
2996 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
3000 /* Ignore registers created by GCSE.
3001 We do this because ... */
3002 if (regno
>= max_gcse_regno
)
3005 /* If the register has already been set in this block, there's
3006 nothing we can do. */
3007 if (! oprs_not_set_p (reg_used
->reg_rtx
, insn
))
3010 /* Find an assignment that sets reg_used and is available
3011 at the start of the block. */
3012 set
= find_avail_set (regno
, insn
);
3017 /* ??? We might be able to handle PARALLELs. Later. */
3018 gcc_assert (GET_CODE (pat
) == SET
);
3020 src
= SET_SRC (pat
);
3022 /* Constant propagation. */
3023 if (gcse_constant_p (src
))
3025 if (constprop_register (insn
, reg_used
->reg_rtx
, src
, alter_jumps
))
3028 global_const_prop_count
++;
3029 if (gcse_file
!= NULL
)
3031 fprintf (gcse_file
, "GLOBAL CONST-PROP: Replacing reg %d in ", regno
);
3032 fprintf (gcse_file
, "insn %d with constant ", INSN_UID (insn
));
3033 print_rtl (gcse_file
, src
);
3034 fprintf (gcse_file
, "\n");
3036 if (INSN_DELETED_P (insn
))
3040 else if (REG_P (src
)
3041 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
3042 && REGNO (src
) != regno
)
3044 if (try_replace_reg (reg_used
->reg_rtx
, src
, insn
))
3047 global_copy_prop_count
++;
3048 if (gcse_file
!= NULL
)
3050 fprintf (gcse_file
, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
3051 regno
, INSN_UID (insn
));
3052 fprintf (gcse_file
, " with reg %d\n", REGNO (src
));
3055 /* The original insn setting reg_used may or may not now be
3056 deletable. We leave the deletion to flow. */
3057 /* FIXME: If it turns out that the insn isn't deletable,
3058 then we may have unnecessarily extended register lifetimes
3059 and made things worse. */
3067 /* Like find_used_regs, but avoid recording uses that appear in
3068 input-output contexts such as zero_extract or pre_dec. This
3069 restricts the cases we consider to those for which local cprop
3070 can legitimately make replacements. */
3073 local_cprop_find_used_regs (rtx
*xptr
, void *data
)
3080 switch (GET_CODE (x
))
3084 case STRICT_LOW_PART
:
3093 /* Can only legitimately appear this early in the context of
3094 stack pushes for function arguments, but handle all of the
3095 codes nonetheless. */
3099 /* Setting a subreg of a register larger than word_mode leaves
3100 the non-written words unchanged. */
3101 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x
))) > BITS_PER_WORD
)
3109 find_used_regs (xptr
, data
);
3112 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3113 their REG_EQUAL notes need updating. */
3116 do_local_cprop (rtx x
, rtx insn
, int alter_jumps
, rtx
*libcall_sp
)
3118 rtx newreg
= NULL
, newcnst
= NULL
;
3120 /* Rule out USE instructions and ASM statements as we don't want to
3121 change the hard registers mentioned. */
3123 && (REGNO (x
) >= FIRST_PSEUDO_REGISTER
3124 || (GET_CODE (PATTERN (insn
)) != USE
3125 && asm_noperands (PATTERN (insn
)) < 0)))
3127 cselib_val
*val
= cselib_lookup (x
, GET_MODE (x
), 0);
3128 struct elt_loc_list
*l
;
3132 for (l
= val
->locs
; l
; l
= l
->next
)
3134 rtx this_rtx
= l
->loc
;
3140 if (gcse_constant_p (this_rtx
))
3142 if (REG_P (this_rtx
) && REGNO (this_rtx
) >= FIRST_PSEUDO_REGISTER
3143 /* Don't copy propagate if it has attached REG_EQUIV note.
3144 At this point this only function parameters should have
3145 REG_EQUIV notes and if the argument slot is used somewhere
3146 explicitly, it means address of parameter has been taken,
3147 so we should not extend the lifetime of the pseudo. */
3148 && (!(note
= find_reg_note (l
->setting_insn
, REG_EQUIV
, NULL_RTX
))
3149 || ! MEM_P (XEXP (note
, 0))))
3152 if (newcnst
&& constprop_register (insn
, x
, newcnst
, alter_jumps
))
3154 /* If we find a case where we can't fix the retval REG_EQUAL notes
3155 match the new register, we either have to abandon this replacement
3156 or fix delete_trivially_dead_insns to preserve the setting insn,
3157 or make it delete the REG_EUAQL note, and fix up all passes that
3158 require the REG_EQUAL note there. */
3161 adjusted
= adjust_libcall_notes (x
, newcnst
, insn
, libcall_sp
);
3162 gcc_assert (adjusted
);
3164 if (gcse_file
!= NULL
)
3166 fprintf (gcse_file
, "LOCAL CONST-PROP: Replacing reg %d in ",
3168 fprintf (gcse_file
, "insn %d with constant ",
3170 print_rtl (gcse_file
, newcnst
);
3171 fprintf (gcse_file
, "\n");
3173 local_const_prop_count
++;
3176 else if (newreg
&& newreg
!= x
&& try_replace_reg (x
, newreg
, insn
))
3178 adjust_libcall_notes (x
, newreg
, insn
, libcall_sp
);
3179 if (gcse_file
!= NULL
)
3182 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
3183 REGNO (x
), INSN_UID (insn
));
3184 fprintf (gcse_file
, " with reg %d\n", REGNO (newreg
));
3186 local_copy_prop_count
++;
3193 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3194 their REG_EQUAL notes need updating to reflect that OLDREG has been
3195 replaced with NEWVAL in INSN. Return true if all substitutions could
3198 adjust_libcall_notes (rtx oldreg
, rtx newval
, rtx insn
, rtx
*libcall_sp
)
3202 while ((end
= *libcall_sp
++))
3204 rtx note
= find_reg_equal_equiv_note (end
);
3211 if (reg_set_between_p (newval
, PREV_INSN (insn
), end
))
3215 note
= find_reg_equal_equiv_note (end
);
3218 if (reg_mentioned_p (newval
, XEXP (note
, 0)))
3221 while ((end
= *libcall_sp
++));
3225 XEXP (note
, 0) = replace_rtx (XEXP (note
, 0), oldreg
, newval
);
3231 #define MAX_NESTED_LIBCALLS 9
3234 local_cprop_pass (int alter_jumps
)
3237 struct reg_use
*reg_used
;
3238 rtx libcall_stack
[MAX_NESTED_LIBCALLS
+ 1], *libcall_sp
;
3239 bool changed
= false;
3241 cselib_init (false);
3242 libcall_sp
= &libcall_stack
[MAX_NESTED_LIBCALLS
];
3244 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
3248 rtx note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
3252 gcc_assert (libcall_sp
!= libcall_stack
);
3253 *--libcall_sp
= XEXP (note
, 0);
3255 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
3258 note
= find_reg_equal_equiv_note (insn
);
3262 note_uses (&PATTERN (insn
), local_cprop_find_used_regs
, NULL
);
3264 local_cprop_find_used_regs (&XEXP (note
, 0), NULL
);
3266 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
3267 reg_used
++, reg_use_count
--)
3268 if (do_local_cprop (reg_used
->reg_rtx
, insn
, alter_jumps
,
3274 if (INSN_DELETED_P (insn
))
3277 while (reg_use_count
);
3279 cselib_process_insn (insn
);
3282 /* Global analysis may get into infinite loops for unreachable blocks. */
3283 if (changed
&& alter_jumps
)
3285 delete_unreachable_blocks ();
3286 free_reg_set_mem ();
3287 alloc_reg_set_mem (max_reg_num ());
3288 compute_sets (get_insns ());
3292 /* Forward propagate copies. This includes copies and constants. Return
3293 nonzero if a change was made. */
3296 cprop (int alter_jumps
)
3302 /* Note we start at block 1. */
3303 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3305 if (gcse_file
!= NULL
)
3306 fprintf (gcse_file
, "\n");
3311 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
3313 /* Reset tables used to keep track of what's still valid [since the
3314 start of the block]. */
3315 reset_opr_set_tables ();
3317 for (insn
= BB_HEAD (bb
);
3318 insn
!= NULL
&& insn
!= NEXT_INSN (BB_END (bb
));
3319 insn
= NEXT_INSN (insn
))
3322 changed
|= cprop_insn (insn
, alter_jumps
);
3324 /* Keep track of everything modified by this insn. */
3325 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
3326 call mark_oprs_set if we turned the insn into a NOTE. */
3327 if (! NOTE_P (insn
))
3328 mark_oprs_set (insn
);
3332 if (gcse_file
!= NULL
)
3333 fprintf (gcse_file
, "\n");
3338 /* Similar to get_condition, only the resulting condition must be
3339 valid at JUMP, instead of at EARLIEST.
3341 This differs from noce_get_condition in ifcvt.c in that we prefer not to
3342 settle for the condition variable in the jump instruction being integral.
3343 We prefer to be able to record the value of a user variable, rather than
3344 the value of a temporary used in a condition. This could be solved by
3345 recording the value of *every* register scaned by canonicalize_condition,
3346 but this would require some code reorganization. */
3349 fis_get_condition (rtx jump
)
3351 return get_condition (jump
, NULL
, false, true);
3354 /* Check the comparison COND to see if we can safely form an implicit set from
3355 it. COND is either an EQ or NE comparison. */
3358 implicit_set_cond_p (rtx cond
)
3360 enum machine_mode mode
= GET_MODE (XEXP (cond
, 0));
3361 rtx cst
= XEXP (cond
, 1);
3363 /* We can't perform this optimization if either operand might be or might
3364 contain a signed zero. */
3365 if (HONOR_SIGNED_ZEROS (mode
))
3367 /* It is sufficient to check if CST is or contains a zero. We must
3368 handle float, complex, and vector. If any subpart is a zero, then
3369 the optimization can't be performed. */
3370 /* ??? The complex and vector checks are not implemented yet. We just
3371 always return zero for them. */
3372 if (GET_CODE (cst
) == CONST_DOUBLE
)
3375 REAL_VALUE_FROM_CONST_DOUBLE (d
, cst
);
3376 if (REAL_VALUES_EQUAL (d
, dconst0
))
3383 return gcse_constant_p (cst
);
3386 /* Find the implicit sets of a function. An "implicit set" is a constraint
3387 on the value of a variable, implied by a conditional jump. For example,
3388 following "if (x == 2)", the then branch may be optimized as though the
3389 conditional performed an "explicit set", in this example, "x = 2". This
3390 function records the set patterns that are implicit at the start of each
3394 find_implicit_sets (void)
3396 basic_block bb
, dest
;
3402 /* Check for more than one successor. */
3403 if (EDGE_COUNT (bb
->succs
) > 1)
3405 cond
= fis_get_condition (BB_END (bb
));
3408 && (GET_CODE (cond
) == EQ
|| GET_CODE (cond
) == NE
)
3409 && REG_P (XEXP (cond
, 0))
3410 && REGNO (XEXP (cond
, 0)) >= FIRST_PSEUDO_REGISTER
3411 && implicit_set_cond_p (cond
))
3413 dest
= GET_CODE (cond
) == EQ
? BRANCH_EDGE (bb
)->dest
3414 : FALLTHRU_EDGE (bb
)->dest
;
3416 if (dest
&& EDGE_COUNT (dest
->preds
) == 1
3417 && dest
!= EXIT_BLOCK_PTR
)
3419 new = gen_rtx_SET (VOIDmode
, XEXP (cond
, 0),
3421 implicit_sets
[dest
->index
] = new;
3424 fprintf(gcse_file
, "Implicit set of reg %d in ",
3425 REGNO (XEXP (cond
, 0)));
3426 fprintf(gcse_file
, "basic block %d\n", dest
->index
);
3434 fprintf (gcse_file
, "Found %d implicit sets\n", count
);
3437 /* Perform one copy/constant propagation pass.
3438 PASS is the pass count. If CPROP_JUMPS is true, perform constant
3439 propagation into conditional jumps. If BYPASS_JUMPS is true,
3440 perform conditional jump bypassing optimizations. */
3443 one_cprop_pass (int pass
, int cprop_jumps
, int bypass_jumps
)
3447 global_const_prop_count
= local_const_prop_count
= 0;
3448 global_copy_prop_count
= local_copy_prop_count
= 0;
3450 local_cprop_pass (cprop_jumps
);
3452 /* Determine implicit sets. */
3453 implicit_sets
= xcalloc (last_basic_block
, sizeof (rtx
));
3454 find_implicit_sets ();
3456 alloc_hash_table (max_cuid
, &set_hash_table
, 1);
3457 compute_hash_table (&set_hash_table
);
3459 /* Free implicit_sets before peak usage. */
3460 free (implicit_sets
);
3461 implicit_sets
= NULL
;
3464 dump_hash_table (gcse_file
, "SET", &set_hash_table
);
3465 if (set_hash_table
.n_elems
> 0)
3467 alloc_cprop_mem (last_basic_block
, set_hash_table
.n_elems
);
3468 compute_cprop_data ();
3469 changed
= cprop (cprop_jumps
);
3471 changed
|= bypass_conditional_jumps ();
3475 free_hash_table (&set_hash_table
);
3479 fprintf (gcse_file
, "CPROP of %s, pass %d: %d bytes needed, ",
3480 current_function_name (), pass
, bytes_used
);
3481 fprintf (gcse_file
, "%d local const props, %d local copy props\n\n",
3482 local_const_prop_count
, local_copy_prop_count
);
3483 fprintf (gcse_file
, "%d global const props, %d global copy props\n\n",
3484 global_const_prop_count
, global_copy_prop_count
);
3486 /* Global analysis may get into infinite loops for unreachable blocks. */
3487 if (changed
&& cprop_jumps
)
3488 delete_unreachable_blocks ();
3493 /* Bypass conditional jumps. */
3495 /* The value of last_basic_block at the beginning of the jump_bypass
3496 pass. The use of redirect_edge_and_branch_force may introduce new
3497 basic blocks, but the data flow analysis is only valid for basic
3498 block indices less than bypass_last_basic_block. */
3500 static int bypass_last_basic_block
;
3502 /* Find a set of REGNO to a constant that is available at the end of basic
3503 block BB. Returns NULL if no such set is found. Based heavily upon
3506 static struct expr
*
3507 find_bypass_set (int regno
, int bb
)
3509 struct expr
*result
= 0;
3514 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
3518 if (TEST_BIT (cprop_avout
[bb
], set
->bitmap_index
))
3520 set
= next_set (regno
, set
);
3526 gcc_assert (GET_CODE (set
->expr
) == SET
);
3528 src
= SET_SRC (set
->expr
);
3529 if (gcse_constant_p (src
))
3535 regno
= REGNO (src
);
3541 /* Subroutine of bypass_block that checks whether a pseudo is killed by
3542 any of the instructions inserted on an edge. Jump bypassing places
3543 condition code setters on CFG edges using insert_insn_on_edge. This
3544 function is required to check that our data flow analysis is still
3545 valid prior to commit_edge_insertions. */
3548 reg_killed_on_edge (rtx reg
, edge e
)
3552 for (insn
= e
->insns
.r
; insn
; insn
= NEXT_INSN (insn
))
3553 if (INSN_P (insn
) && reg_set_p (reg
, insn
))
3559 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
3560 basic block BB which has more than one predecessor. If not NULL, SETCC
3561 is the first instruction of BB, which is immediately followed by JUMP_INSN
3562 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
3563 Returns nonzero if a change was made.
3565 During the jump bypassing pass, we may place copies of SETCC instructions
3566 on CFG edges. The following routine must be careful to pay attention to
3567 these inserted insns when performing its transformations. */
3570 bypass_block (basic_block bb
, rtx setcc
, rtx jump
)
3575 int may_be_loop_header
;
3579 insn
= (setcc
!= NULL
) ? setcc
: jump
;
3581 /* Determine set of register uses in INSN. */
3583 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
3584 note
= find_reg_equal_equiv_note (insn
);
3586 find_used_regs (&XEXP (note
, 0), NULL
);
3588 may_be_loop_header
= false;
3589 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3590 if (e
->flags
& EDGE_DFS_BACK
)
3592 may_be_loop_header
= true;
3597 for (ei
= ei_start (bb
->preds
); (e
= ei_safe_edge (ei
)); )
3601 if (e
->flags
& EDGE_COMPLEX
)
3607 /* We can't redirect edges from new basic blocks. */
3608 if (e
->src
->index
>= bypass_last_basic_block
)
3614 /* The irreducible loops created by redirecting of edges entering the
3615 loop from outside would decrease effectiveness of some of the following
3616 optimizations, so prevent this. */
3617 if (may_be_loop_header
3618 && !(e
->flags
& EDGE_DFS_BACK
))
3624 for (i
= 0; i
< reg_use_count
; i
++)
3626 struct reg_use
*reg_used
= ®_use_table
[i
];
3627 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
3628 basic_block dest
, old_dest
;
3632 if (regno
>= max_gcse_regno
)
3635 set
= find_bypass_set (regno
, e
->src
->index
);
3640 /* Check the data flow is valid after edge insertions. */
3641 if (e
->insns
.r
&& reg_killed_on_edge (reg_used
->reg_rtx
, e
))
3644 src
= SET_SRC (pc_set (jump
));
3647 src
= simplify_replace_rtx (src
,
3648 SET_DEST (PATTERN (setcc
)),
3649 SET_SRC (PATTERN (setcc
)));
3651 new = simplify_replace_rtx (src
, reg_used
->reg_rtx
,
3652 SET_SRC (set
->expr
));
3654 /* Jump bypassing may have already placed instructions on
3655 edges of the CFG. We can't bypass an outgoing edge that
3656 has instructions associated with it, as these insns won't
3657 get executed if the incoming edge is redirected. */
3661 edest
= FALLTHRU_EDGE (bb
);
3662 dest
= edest
->insns
.r
? NULL
: edest
->dest
;
3664 else if (GET_CODE (new) == LABEL_REF
)
3668 dest
= BLOCK_FOR_INSN (XEXP (new, 0));
3669 /* Don't bypass edges containing instructions. */
3670 FOR_EACH_EDGE (edest
, ei2
, bb
->succs
)
3671 if (edest
->dest
== dest
&& edest
->insns
.r
)
3680 /* Avoid unification of the edge with other edges from original
3681 branch. We would end up emitting the instruction on "both"
3684 if (dest
&& setcc
&& !CC0_P (SET_DEST (PATTERN (setcc
))))
3689 FOR_EACH_EDGE (e2
, ei2
, e
->src
->succs
)
3690 if (e2
->dest
== dest
)
3700 && dest
!= EXIT_BLOCK_PTR
)
3702 redirect_edge_and_branch_force (e
, dest
);
3704 /* Copy the register setter to the redirected edge.
3705 Don't copy CC0 setters, as CC0 is dead after jump. */
3708 rtx pat
= PATTERN (setcc
);
3709 if (!CC0_P (SET_DEST (pat
)))
3710 insert_insn_on_edge (copy_insn (pat
), e
);
3713 if (gcse_file
!= NULL
)
3715 fprintf (gcse_file
, "JUMP-BYPASS: Proved reg %d "
3716 "in jump_insn %d equals constant ",
3717 regno
, INSN_UID (jump
));
3718 print_rtl (gcse_file
, SET_SRC (set
->expr
));
3719 fprintf (gcse_file
, "\nBypass edge from %d->%d to %d\n",
3720 e
->src
->index
, old_dest
->index
, dest
->index
);
3733 /* Find basic blocks with more than one predecessor that only contain a
3734 single conditional jump. If the result of the comparison is known at
3735 compile-time from any incoming edge, redirect that edge to the
3736 appropriate target. Returns nonzero if a change was made.
3738 This function is now mis-named, because we also handle indirect jumps. */
3741 bypass_conditional_jumps (void)
3749 /* Note we start at block 1. */
3750 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3753 bypass_last_basic_block
= last_basic_block
;
3754 mark_dfs_back_edges ();
3757 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
,
3758 EXIT_BLOCK_PTR
, next_bb
)
3760 /* Check for more than one predecessor. */
3761 if (EDGE_COUNT (bb
->preds
) > 1)
3764 for (insn
= BB_HEAD (bb
);
3765 insn
!= NULL
&& insn
!= NEXT_INSN (BB_END (bb
));
3766 insn
= NEXT_INSN (insn
))
3767 if (NONJUMP_INSN_P (insn
))
3771 if (GET_CODE (PATTERN (insn
)) != SET
)
3774 dest
= SET_DEST (PATTERN (insn
));
3775 if (REG_P (dest
) || CC0_P (dest
))
3780 else if (JUMP_P (insn
))
3782 if ((any_condjump_p (insn
) || computed_jump_p (insn
))
3783 && onlyjump_p (insn
))
3784 changed
|= bypass_block (bb
, setcc
, insn
);
3787 else if (INSN_P (insn
))
3792 /* If we bypassed any register setting insns, we inserted a
3793 copy on the redirected edge. These need to be committed. */
3795 commit_edge_insertions();
3800 /* Compute PRE+LCM working variables. */
3802 /* Local properties of expressions. */
3803 /* Nonzero for expressions that are transparent in the block. */
3804 static sbitmap
*transp
;
3806 /* Nonzero for expressions that are transparent at the end of the block.
3807 This is only zero for expressions killed by abnormal critical edge
3808 created by a calls. */
3809 static sbitmap
*transpout
;
3811 /* Nonzero for expressions that are computed (available) in the block. */
3812 static sbitmap
*comp
;
3814 /* Nonzero for expressions that are locally anticipatable in the block. */
3815 static sbitmap
*antloc
;
3817 /* Nonzero for expressions where this block is an optimal computation
3819 static sbitmap
*pre_optimal
;
3821 /* Nonzero for expressions which are redundant in a particular block. */
3822 static sbitmap
*pre_redundant
;
3824 /* Nonzero for expressions which should be inserted on a specific edge. */
3825 static sbitmap
*pre_insert_map
;
3827 /* Nonzero for expressions which should be deleted in a specific block. */
3828 static sbitmap
*pre_delete_map
;
3830 /* Contains the edge_list returned by pre_edge_lcm. */
3831 static struct edge_list
*edge_list
;
3833 /* Redundant insns. */
3834 static sbitmap pre_redundant_insns
;
3836 /* Allocate vars used for PRE analysis. */
3839 alloc_pre_mem (int n_blocks
, int n_exprs
)
3841 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3842 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3843 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3846 pre_redundant
= NULL
;
3847 pre_insert_map
= NULL
;
3848 pre_delete_map
= NULL
;
3849 ae_kill
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3851 /* pre_insert and pre_delete are allocated later. */
3854 /* Free vars used for PRE analysis. */
3859 sbitmap_vector_free (transp
);
3860 sbitmap_vector_free (comp
);
3862 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
3865 sbitmap_vector_free (pre_optimal
);
3867 sbitmap_vector_free (pre_redundant
);
3869 sbitmap_vector_free (pre_insert_map
);
3871 sbitmap_vector_free (pre_delete_map
);
3873 transp
= comp
= NULL
;
3874 pre_optimal
= pre_redundant
= pre_insert_map
= pre_delete_map
= NULL
;
3877 /* Top level routine to do the dataflow analysis needed by PRE. */
3880 compute_pre_data (void)
3882 sbitmap trapping_expr
;
3886 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
3887 sbitmap_vector_zero (ae_kill
, last_basic_block
);
3889 /* Collect expressions which might trap. */
3890 trapping_expr
= sbitmap_alloc (expr_hash_table
.n_elems
);
3891 sbitmap_zero (trapping_expr
);
3892 for (ui
= 0; ui
< expr_hash_table
.size
; ui
++)
3895 for (e
= expr_hash_table
.table
[ui
]; e
!= NULL
; e
= e
->next_same_hash
)
3896 if (may_trap_p (e
->expr
))
3897 SET_BIT (trapping_expr
, e
->bitmap_index
);
3900 /* Compute ae_kill for each basic block using:
3910 /* If the current block is the destination of an abnormal edge, we
3911 kill all trapping expressions because we won't be able to properly
3912 place the instruction on the edge. So make them neither
3913 anticipatable nor transparent. This is fairly conservative. */
3914 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3915 if (e
->flags
& EDGE_ABNORMAL
)
3917 sbitmap_difference (antloc
[bb
->index
], antloc
[bb
->index
], trapping_expr
);
3918 sbitmap_difference (transp
[bb
->index
], transp
[bb
->index
], trapping_expr
);
3922 sbitmap_a_or_b (ae_kill
[bb
->index
], transp
[bb
->index
], comp
[bb
->index
]);
3923 sbitmap_not (ae_kill
[bb
->index
], ae_kill
[bb
->index
]);
3926 edge_list
= pre_edge_lcm (gcse_file
, expr_hash_table
.n_elems
, transp
, comp
, antloc
,
3927 ae_kill
, &pre_insert_map
, &pre_delete_map
);
3928 sbitmap_vector_free (antloc
);
3930 sbitmap_vector_free (ae_kill
);
3932 sbitmap_free (trapping_expr
);
3937 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
3940 VISITED is a pointer to a working buffer for tracking which BB's have
3941 been visited. It is NULL for the top-level call.
3943 We treat reaching expressions that go through blocks containing the same
3944 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3945 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3946 2 as not reaching. The intent is to improve the probability of finding
3947 only one reaching expression and to reduce register lifetimes by picking
3948 the closest such expression. */
3951 pre_expr_reaches_here_p_work (basic_block occr_bb
, struct expr
*expr
, basic_block bb
, char *visited
)
3956 FOR_EACH_EDGE (pred
, ei
, bb
->preds
)
3958 basic_block pred_bb
= pred
->src
;
3960 if (pred
->src
== ENTRY_BLOCK_PTR
3961 /* Has predecessor has already been visited? */
3962 || visited
[pred_bb
->index
])
3963 ;/* Nothing to do. */
3965 /* Does this predecessor generate this expression? */
3966 else if (TEST_BIT (comp
[pred_bb
->index
], expr
->bitmap_index
))
3968 /* Is this the occurrence we're looking for?
3969 Note that there's only one generating occurrence per block
3970 so we just need to check the block number. */
3971 if (occr_bb
== pred_bb
)
3974 visited
[pred_bb
->index
] = 1;
3976 /* Ignore this predecessor if it kills the expression. */
3977 else if (! TEST_BIT (transp
[pred_bb
->index
], expr
->bitmap_index
))
3978 visited
[pred_bb
->index
] = 1;
3980 /* Neither gen nor kill. */
3983 visited
[pred_bb
->index
] = 1;
3984 if (pre_expr_reaches_here_p_work (occr_bb
, expr
, pred_bb
, visited
))
3989 /* All paths have been checked. */
3993 /* The wrapper for pre_expr_reaches_here_work that ensures that any
3994 memory allocated for that function is returned. */
3997 pre_expr_reaches_here_p (basic_block occr_bb
, struct expr
*expr
, basic_block bb
)
4000 char *visited
= xcalloc (last_basic_block
, 1);
4002 rval
= pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
);
4009 /* Given an expr, generate RTL which we can insert at the end of a BB,
4010 or on an edge. Set the block number of any insns generated to
4014 process_insert_insn (struct expr
*expr
)
4016 rtx reg
= expr
->reaching_reg
;
4017 rtx exp
= copy_rtx (expr
->expr
);
4022 /* If the expression is something that's an operand, like a constant,
4023 just copy it to a register. */
4024 if (general_operand (exp
, GET_MODE (reg
)))
4025 emit_move_insn (reg
, exp
);
4027 /* Otherwise, make a new insn to compute this expression and make sure the
4028 insn will be recognized (this also adds any needed CLOBBERs). Copy the
4029 expression to make sure we don't have any sharing issues. */
4032 rtx insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, exp
));
4034 if (insn_invalid_p (insn
))
4045 /* Add EXPR to the end of basic block BB.
4047 This is used by both the PRE and code hoisting.
4049 For PRE, we want to verify that the expr is either transparent
4050 or locally anticipatable in the target block. This check makes
4051 no sense for code hoisting. */
4054 insert_insn_end_bb (struct expr
*expr
, basic_block bb
, int pre
)
4056 rtx insn
= BB_END (bb
);
4058 rtx reg
= expr
->reaching_reg
;
4059 int regno
= REGNO (reg
);
4062 pat
= process_insert_insn (expr
);
4063 gcc_assert (pat
&& INSN_P (pat
));
4066 while (NEXT_INSN (pat_end
) != NULL_RTX
)
4067 pat_end
= NEXT_INSN (pat_end
);
4069 /* If the last insn is a jump, insert EXPR in front [taking care to
4070 handle cc0, etc. properly]. Similarly we need to care trapping
4071 instructions in presence of non-call exceptions. */
4074 || (NONJUMP_INSN_P (insn
)
4075 && (EDGE_COUNT (bb
->succs
) > 1
4076 || EDGE_SUCC (bb
, 0)->flags
& EDGE_ABNORMAL
)))
4081 /* It should always be the case that we can put these instructions
4082 anywhere in the basic block with performing PRE optimizations.
4084 gcc_assert (!NONJUMP_INSN_P (insn
) || !pre
4085 || TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
4086 || TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
));
4088 /* If this is a jump table, then we can't insert stuff here. Since
4089 we know the previous real insn must be the tablejump, we insert
4090 the new instruction just before the tablejump. */
4091 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
4092 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
4093 insn
= prev_real_insn (insn
);
4096 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4097 if cc0 isn't set. */
4098 note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
4100 insn
= XEXP (note
, 0);
4103 rtx maybe_cc0_setter
= prev_nonnote_insn (insn
);
4104 if (maybe_cc0_setter
4105 && INSN_P (maybe_cc0_setter
)
4106 && sets_cc0_p (PATTERN (maybe_cc0_setter
)))
4107 insn
= maybe_cc0_setter
;
4110 /* FIXME: What if something in cc0/jump uses value set in new insn? */
4111 new_insn
= emit_insn_before (pat
, insn
);
4114 /* Likewise if the last insn is a call, as will happen in the presence
4115 of exception handling. */
4116 else if (CALL_P (insn
)
4117 && (EDGE_COUNT (bb
->succs
) > 1 || EDGE_SUCC (bb
, 0)->flags
& EDGE_ABNORMAL
))
4119 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
4120 we search backward and place the instructions before the first
4121 parameter is loaded. Do this for everyone for consistency and a
4122 presumption that we'll get better code elsewhere as well.
4124 It should always be the case that we can put these instructions
4125 anywhere in the basic block with performing PRE optimizations.
4129 || TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
4130 || TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
));
4132 /* Since different machines initialize their parameter registers
4133 in different orders, assume nothing. Collect the set of all
4134 parameter registers. */
4135 insn
= find_first_parameter_load (insn
, BB_HEAD (bb
));
4137 /* If we found all the parameter loads, then we want to insert
4138 before the first parameter load.
4140 If we did not find all the parameter loads, then we might have
4141 stopped on the head of the block, which could be a CODE_LABEL.
4142 If we inserted before the CODE_LABEL, then we would be putting
4143 the insn in the wrong basic block. In that case, put the insn
4144 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
4145 while (LABEL_P (insn
)
4146 || NOTE_INSN_BASIC_BLOCK_P (insn
))
4147 insn
= NEXT_INSN (insn
);
4149 new_insn
= emit_insn_before (pat
, insn
);
4152 new_insn
= emit_insn_after (pat
, insn
);
4158 add_label_notes (PATTERN (pat
), new_insn
);
4159 note_stores (PATTERN (pat
), record_set_info
, pat
);
4163 pat
= NEXT_INSN (pat
);
4166 gcse_create_count
++;
4170 fprintf (gcse_file
, "PRE/HOIST: end of bb %d, insn %d, ",
4171 bb
->index
, INSN_UID (new_insn
));
4172 fprintf (gcse_file
, "copying expression %d to reg %d\n",
4173 expr
->bitmap_index
, regno
);
4177 /* Insert partially redundant expressions on edges in the CFG to make
4178 the expressions fully redundant. */
4181 pre_edge_insert (struct edge_list
*edge_list
, struct expr
**index_map
)
4183 int e
, i
, j
, num_edges
, set_size
, did_insert
= 0;
4186 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
4187 if it reaches any of the deleted expressions. */
4189 set_size
= pre_insert_map
[0]->size
;
4190 num_edges
= NUM_EDGES (edge_list
);
4191 inserted
= sbitmap_vector_alloc (num_edges
, expr_hash_table
.n_elems
);
4192 sbitmap_vector_zero (inserted
, num_edges
);
4194 for (e
= 0; e
< num_edges
; e
++)
4197 basic_block bb
= INDEX_EDGE_PRED_BB (edge_list
, e
);
4199 for (i
= indx
= 0; i
< set_size
; i
++, indx
+= SBITMAP_ELT_BITS
)
4201 SBITMAP_ELT_TYPE insert
= pre_insert_map
[e
]->elms
[i
];
4203 for (j
= indx
; insert
&& j
< (int) expr_hash_table
.n_elems
; j
++, insert
>>= 1)
4204 if ((insert
& 1) != 0 && index_map
[j
]->reaching_reg
!= NULL_RTX
)
4206 struct expr
*expr
= index_map
[j
];
4209 /* Now look at each deleted occurrence of this expression. */
4210 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4212 if (! occr
->deleted_p
)
4215 /* Insert this expression on this edge if if it would
4216 reach the deleted occurrence in BB. */
4217 if (!TEST_BIT (inserted
[e
], j
))
4220 edge eg
= INDEX_EDGE (edge_list
, e
);
4222 /* We can't insert anything on an abnormal and
4223 critical edge, so we insert the insn at the end of
4224 the previous block. There are several alternatives
4225 detailed in Morgans book P277 (sec 10.5) for
4226 handling this situation. This one is easiest for
4229 if ((eg
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
4230 insert_insn_end_bb (index_map
[j
], bb
, 0);
4233 insn
= process_insert_insn (index_map
[j
]);
4234 insert_insn_on_edge (insn
, eg
);
4239 fprintf (gcse_file
, "PRE/HOIST: edge (%d,%d), ",
4241 INDEX_EDGE_SUCC_BB (edge_list
, e
)->index
);
4242 fprintf (gcse_file
, "copy expression %d\n",
4243 expr
->bitmap_index
);
4246 update_ld_motion_stores (expr
);
4247 SET_BIT (inserted
[e
], j
);
4249 gcse_create_count
++;
4256 sbitmap_vector_free (inserted
);
4260 /* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
4261 Given "old_reg <- expr" (INSN), instead of adding after it
4262 reaching_reg <- old_reg
4263 it's better to do the following:
4264 reaching_reg <- expr
4265 old_reg <- reaching_reg
4266 because this way copy propagation can discover additional PRE
4267 opportunities. But if this fails, we try the old way.
4268 When "expr" is a store, i.e.
4269 given "MEM <- old_reg", instead of adding after it
4270 reaching_reg <- old_reg
4271 it's better to add it before as follows:
4272 reaching_reg <- old_reg
4273 MEM <- reaching_reg. */
4276 pre_insert_copy_insn (struct expr
*expr
, rtx insn
)
4278 rtx reg
= expr
->reaching_reg
;
4279 int regno
= REGNO (reg
);
4280 int indx
= expr
->bitmap_index
;
4281 rtx pat
= PATTERN (insn
);
4286 /* This block matches the logic in hash_scan_insn. */
4287 switch (GET_CODE (pat
))
4294 /* Search through the parallel looking for the set whose
4295 source was the expression that we're interested in. */
4297 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
4299 rtx x
= XVECEXP (pat
, 0, i
);
4300 if (GET_CODE (x
) == SET
4301 && expr_equiv_p (SET_SRC (x
), expr
->expr
))
4313 if (REG_P (SET_DEST (set
)))
4315 old_reg
= SET_DEST (set
);
4316 /* Check if we can modify the set destination in the original insn. */
4317 if (validate_change (insn
, &SET_DEST (set
), reg
, 0))
4319 new_insn
= gen_move_insn (old_reg
, reg
);
4320 new_insn
= emit_insn_after (new_insn
, insn
);
4322 /* Keep register set table up to date. */
4323 replace_one_set (REGNO (old_reg
), insn
, new_insn
);
4324 record_one_set (regno
, insn
);
4328 new_insn
= gen_move_insn (reg
, old_reg
);
4329 new_insn
= emit_insn_after (new_insn
, insn
);
4331 /* Keep register set table up to date. */
4332 record_one_set (regno
, new_insn
);
4335 else /* This is possible only in case of a store to memory. */
4337 old_reg
= SET_SRC (set
);
4338 new_insn
= gen_move_insn (reg
, old_reg
);
4340 /* Check if we can modify the set source in the original insn. */
4341 if (validate_change (insn
, &SET_SRC (set
), reg
, 0))
4342 new_insn
= emit_insn_before (new_insn
, insn
);
4344 new_insn
= emit_insn_after (new_insn
, insn
);
4346 /* Keep register set table up to date. */
4347 record_one_set (regno
, new_insn
);
4350 gcse_create_count
++;
4354 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
4355 BLOCK_NUM (insn
), INSN_UID (new_insn
), indx
,
4356 INSN_UID (insn
), regno
);
4359 /* Copy available expressions that reach the redundant expression
4360 to `reaching_reg'. */
4363 pre_insert_copies (void)
4365 unsigned int i
, added_copy
;
4370 /* For each available expression in the table, copy the result to
4371 `reaching_reg' if the expression reaches a deleted one.
4373 ??? The current algorithm is rather brute force.
4374 Need to do some profiling. */
4376 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4377 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
4379 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
4380 we don't want to insert a copy here because the expression may not
4381 really be redundant. So only insert an insn if the expression was
4382 deleted. This test also avoids further processing if the
4383 expression wasn't deleted anywhere. */
4384 if (expr
->reaching_reg
== NULL
)
4387 /* Set when we add a copy for that expression. */
4390 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4392 if (! occr
->deleted_p
)
4395 for (avail
= expr
->avail_occr
; avail
!= NULL
; avail
= avail
->next
)
4397 rtx insn
= avail
->insn
;
4399 /* No need to handle this one if handled already. */
4400 if (avail
->copied_p
)
4403 /* Don't handle this one if it's a redundant one. */
4404 if (TEST_BIT (pre_redundant_insns
, INSN_CUID (insn
)))
4407 /* Or if the expression doesn't reach the deleted one. */
4408 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail
->insn
),
4410 BLOCK_FOR_INSN (occr
->insn
)))
4415 /* Copy the result of avail to reaching_reg. */
4416 pre_insert_copy_insn (expr
, insn
);
4417 avail
->copied_p
= 1;
4422 update_ld_motion_stores (expr
);
4426 /* Emit move from SRC to DEST noting the equivalence with expression computed
4429 gcse_emit_move_after (rtx src
, rtx dest
, rtx insn
)
4432 rtx set
= single_set (insn
), set2
;
4436 /* This should never fail since we're creating a reg->reg copy
4437 we've verified to be valid. */
4439 new = emit_insn_after (gen_move_insn (dest
, src
), insn
);
4441 /* Note the equivalence for local CSE pass. */
4442 set2
= single_set (new);
4443 if (!set2
|| !rtx_equal_p (SET_DEST (set2
), dest
))
4445 if ((note
= find_reg_equal_equiv_note (insn
)))
4446 eqv
= XEXP (note
, 0);
4448 eqv
= SET_SRC (set
);
4450 set_unique_reg_note (new, REG_EQUAL
, copy_insn_1 (eqv
));
4455 /* Delete redundant computations.
4456 Deletion is done by changing the insn to copy the `reaching_reg' of
4457 the expression into the result of the SET. It is left to later passes
4458 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
4460 Returns nonzero if a change is made. */
4471 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4472 for (expr
= expr_hash_table
.table
[i
];
4474 expr
= expr
->next_same_hash
)
4476 int indx
= expr
->bitmap_index
;
4478 /* We only need to search antic_occr since we require
4481 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4483 rtx insn
= occr
->insn
;
4485 basic_block bb
= BLOCK_FOR_INSN (insn
);
4487 /* We only delete insns that have a single_set. */
4488 if (TEST_BIT (pre_delete_map
[bb
->index
], indx
)
4489 && (set
= single_set (insn
)) != 0)
4491 /* Create a pseudo-reg to store the result of reaching
4492 expressions into. Get the mode for the new pseudo from
4493 the mode of the original destination pseudo. */
4494 if (expr
->reaching_reg
== NULL
)
4496 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
4498 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
4500 occr
->deleted_p
= 1;
4501 SET_BIT (pre_redundant_insns
, INSN_CUID (insn
));
4508 "PRE: redundant insn %d (expression %d) in ",
4509 INSN_UID (insn
), indx
);
4510 fprintf (gcse_file
, "bb %d, reaching reg is %d\n",
4511 bb
->index
, REGNO (expr
->reaching_reg
));
4520 /* Perform GCSE optimizations using PRE.
4521 This is called by one_pre_gcse_pass after all the dataflow analysis
4524 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
4525 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
4526 Compiler Design and Implementation.
4528 ??? A new pseudo reg is created to hold the reaching expression. The nice
4529 thing about the classical approach is that it would try to use an existing
4530 reg. If the register can't be adequately optimized [i.e. we introduce
4531 reload problems], one could add a pass here to propagate the new register
4534 ??? We don't handle single sets in PARALLELs because we're [currently] not
4535 able to copy the rest of the parallel when we insert copies to create full
4536 redundancies from partial redundancies. However, there's no reason why we
4537 can't handle PARALLELs in the cases where there are no partial
4544 int did_insert
, changed
;
4545 struct expr
**index_map
;
4548 /* Compute a mapping from expression number (`bitmap_index') to
4549 hash table entry. */
4551 index_map
= xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
4552 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4553 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
4554 index_map
[expr
->bitmap_index
] = expr
;
4556 /* Reset bitmap used to track which insns are redundant. */
4557 pre_redundant_insns
= sbitmap_alloc (max_cuid
);
4558 sbitmap_zero (pre_redundant_insns
);
4560 /* Delete the redundant insns first so that
4561 - we know what register to use for the new insns and for the other
4562 ones with reaching expressions
4563 - we know which insns are redundant when we go to create copies */
4565 changed
= pre_delete ();
4567 did_insert
= pre_edge_insert (edge_list
, index_map
);
4569 /* In other places with reaching expressions, copy the expression to the
4570 specially allocated pseudo-reg that reaches the redundant expr. */
4571 pre_insert_copies ();
4574 commit_edge_insertions ();
4579 sbitmap_free (pre_redundant_insns
);
4583 /* Top level routine to perform one PRE GCSE pass.
4585 Return nonzero if a change was made. */
4588 one_pre_gcse_pass (int pass
)
4592 gcse_subst_count
= 0;
4593 gcse_create_count
= 0;
4595 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
4596 add_noreturn_fake_exit_edges ();
4598 compute_ld_motion_mems ();
4600 compute_hash_table (&expr_hash_table
);
4601 trim_ld_motion_mems ();
4603 dump_hash_table (gcse_file
, "Expression", &expr_hash_table
);
4605 if (expr_hash_table
.n_elems
> 0)
4607 alloc_pre_mem (last_basic_block
, expr_hash_table
.n_elems
);
4608 compute_pre_data ();
4609 changed
|= pre_gcse ();
4610 free_edge_list (edge_list
);
4615 remove_fake_exit_edges ();
4616 free_hash_table (&expr_hash_table
);
4620 fprintf (gcse_file
, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
4621 current_function_name (), pass
, bytes_used
);
4622 fprintf (gcse_file
, "%d substs, %d insns created\n",
4623 gcse_subst_count
, gcse_create_count
);
4629 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
4630 If notes are added to an insn which references a CODE_LABEL, the
4631 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
4632 because the following loop optimization pass requires them. */
4634 /* ??? This is very similar to the loop.c add_label_notes function. We
4635 could probably share code here. */
4637 /* ??? If there was a jump optimization pass after gcse and before loop,
4638 then we would not need to do this here, because jump would add the
4639 necessary REG_LABEL notes. */
4642 add_label_notes (rtx x
, rtx insn
)
4644 enum rtx_code code
= GET_CODE (x
);
4648 if (code
== LABEL_REF
&& !LABEL_REF_NONLOCAL_P (x
))
4650 /* This code used to ignore labels that referred to dispatch tables to
4651 avoid flow generating (slightly) worse code.
4653 We no longer ignore such label references (see LABEL_REF handling in
4654 mark_jump_label for additional information). */
4656 REG_NOTES (insn
) = gen_rtx_INSN_LIST (REG_LABEL
, XEXP (x
, 0),
4658 if (LABEL_P (XEXP (x
, 0)))
4659 LABEL_NUSES (XEXP (x
, 0))++;
4663 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
4666 add_label_notes (XEXP (x
, i
), insn
);
4667 else if (fmt
[i
] == 'E')
4668 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4669 add_label_notes (XVECEXP (x
, i
, j
), insn
);
4673 /* Compute transparent outgoing information for each block.
4675 An expression is transparent to an edge unless it is killed by
4676 the edge itself. This can only happen with abnormal control flow,
4677 when the edge is traversed through a call. This happens with
4678 non-local labels and exceptions.
4680 This would not be necessary if we split the edge. While this is
4681 normally impossible for abnormal critical edges, with some effort
4682 it should be possible with exception handling, since we still have
4683 control over which handler should be invoked. But due to increased
4684 EH table sizes, this may not be worthwhile. */
4687 compute_transpout (void)
4693 sbitmap_vector_ones (transpout
, last_basic_block
);
4697 /* Note that flow inserted a nop a the end of basic blocks that
4698 end in call instructions for reasons other than abnormal
4700 if (! CALL_P (BB_END (bb
)))
4703 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4704 for (expr
= expr_hash_table
.table
[i
]; expr
; expr
= expr
->next_same_hash
)
4705 if (MEM_P (expr
->expr
))
4707 if (GET_CODE (XEXP (expr
->expr
, 0)) == SYMBOL_REF
4708 && CONSTANT_POOL_ADDRESS_P (XEXP (expr
->expr
, 0)))
4711 /* ??? Optimally, we would use interprocedural alias
4712 analysis to determine if this mem is actually killed
4714 RESET_BIT (transpout
[bb
->index
], expr
->bitmap_index
);
4719 /* Code Hoisting variables and subroutines. */
4721 /* Very busy expressions. */
4722 static sbitmap
*hoist_vbein
;
4723 static sbitmap
*hoist_vbeout
;
4725 /* Hoistable expressions. */
4726 static sbitmap
*hoist_exprs
;
4728 /* ??? We could compute post dominators and run this algorithm in
4729 reverse to perform tail merging, doing so would probably be
4730 more effective than the tail merging code in jump.c.
4732 It's unclear if tail merging could be run in parallel with
4733 code hoisting. It would be nice. */
4735 /* Allocate vars used for code hoisting analysis. */
4738 alloc_code_hoist_mem (int n_blocks
, int n_exprs
)
4740 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4741 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4742 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4744 hoist_vbein
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4745 hoist_vbeout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4746 hoist_exprs
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4747 transpout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4750 /* Free vars used for code hoisting analysis. */
4753 free_code_hoist_mem (void)
4755 sbitmap_vector_free (antloc
);
4756 sbitmap_vector_free (transp
);
4757 sbitmap_vector_free (comp
);
4759 sbitmap_vector_free (hoist_vbein
);
4760 sbitmap_vector_free (hoist_vbeout
);
4761 sbitmap_vector_free (hoist_exprs
);
4762 sbitmap_vector_free (transpout
);
4764 free_dominance_info (CDI_DOMINATORS
);
4767 /* Compute the very busy expressions at entry/exit from each block.
4769 An expression is very busy if all paths from a given point
4770 compute the expression. */
4773 compute_code_hoist_vbeinout (void)
4775 int changed
, passes
;
4778 sbitmap_vector_zero (hoist_vbeout
, last_basic_block
);
4779 sbitmap_vector_zero (hoist_vbein
, last_basic_block
);
4788 /* We scan the blocks in the reverse order to speed up
4790 FOR_EACH_BB_REVERSE (bb
)
4792 changed
|= sbitmap_a_or_b_and_c_cg (hoist_vbein
[bb
->index
], antloc
[bb
->index
],
4793 hoist_vbeout
[bb
->index
], transp
[bb
->index
]);
4794 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
4795 sbitmap_intersection_of_succs (hoist_vbeout
[bb
->index
], hoist_vbein
, bb
->index
);
4802 fprintf (gcse_file
, "hoisting vbeinout computation: %d passes\n", passes
);
4805 /* Top level routine to do the dataflow analysis needed by code hoisting. */
4808 compute_code_hoist_data (void)
4810 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
4811 compute_transpout ();
4812 compute_code_hoist_vbeinout ();
4813 calculate_dominance_info (CDI_DOMINATORS
);
4815 fprintf (gcse_file
, "\n");
4818 /* Determine if the expression identified by EXPR_INDEX would
4819 reach BB unimpared if it was placed at the end of EXPR_BB.
4821 It's unclear exactly what Muchnick meant by "unimpared". It seems
4822 to me that the expression must either be computed or transparent in
4823 *every* block in the path(s) from EXPR_BB to BB. Any other definition
4824 would allow the expression to be hoisted out of loops, even if
4825 the expression wasn't a loop invariant.
4827 Contrast this to reachability for PRE where an expression is
4828 considered reachable if *any* path reaches instead of *all*
4832 hoist_expr_reaches_here_p (basic_block expr_bb
, int expr_index
, basic_block bb
, char *visited
)
4836 int visited_allocated_locally
= 0;
4839 if (visited
== NULL
)
4841 visited_allocated_locally
= 1;
4842 visited
= xcalloc (last_basic_block
, 1);
4845 FOR_EACH_EDGE (pred
, ei
, bb
->preds
)
4847 basic_block pred_bb
= pred
->src
;
4849 if (pred
->src
== ENTRY_BLOCK_PTR
)
4851 else if (pred_bb
== expr_bb
)
4853 else if (visited
[pred_bb
->index
])
4856 /* Does this predecessor generate this expression? */
4857 else if (TEST_BIT (comp
[pred_bb
->index
], expr_index
))
4859 else if (! TEST_BIT (transp
[pred_bb
->index
], expr_index
))
4865 visited
[pred_bb
->index
] = 1;
4866 if (! hoist_expr_reaches_here_p (expr_bb
, expr_index
,
4871 if (visited_allocated_locally
)
4874 return (pred
== NULL
);
4877 /* Actually perform code hoisting. */
4882 basic_block bb
, dominated
;
4884 unsigned int domby_len
;
4886 struct expr
**index_map
;
4889 sbitmap_vector_zero (hoist_exprs
, last_basic_block
);
4891 /* Compute a mapping from expression number (`bitmap_index') to
4892 hash table entry. */
4894 index_map
= xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
4895 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4896 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
4897 index_map
[expr
->bitmap_index
] = expr
;
4899 /* Walk over each basic block looking for potentially hoistable
4900 expressions, nothing gets hoisted from the entry block. */
4904 int insn_inserted_p
;
4906 domby_len
= get_dominated_by (CDI_DOMINATORS
, bb
, &domby
);
4907 /* Examine each expression that is very busy at the exit of this
4908 block. These are the potentially hoistable expressions. */
4909 for (i
= 0; i
< hoist_vbeout
[bb
->index
]->n_bits
; i
++)
4913 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
)
4914 && TEST_BIT (transpout
[bb
->index
], i
))
4916 /* We've found a potentially hoistable expression, now
4917 we look at every block BB dominates to see if it
4918 computes the expression. */
4919 for (j
= 0; j
< domby_len
; j
++)
4921 dominated
= domby
[j
];
4922 /* Ignore self dominance. */
4923 if (bb
== dominated
)
4925 /* We've found a dominated block, now see if it computes
4926 the busy expression and whether or not moving that
4927 expression to the "beginning" of that block is safe. */
4928 if (!TEST_BIT (antloc
[dominated
->index
], i
))
4931 /* Note if the expression would reach the dominated block
4932 unimpared if it was placed at the end of BB.
4934 Keep track of how many times this expression is hoistable
4935 from a dominated block into BB. */
4936 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
4940 /* If we found more than one hoistable occurrence of this
4941 expression, then note it in the bitmap of expressions to
4942 hoist. It makes no sense to hoist things which are computed
4943 in only one BB, and doing so tends to pessimize register
4944 allocation. One could increase this value to try harder
4945 to avoid any possible code expansion due to register
4946 allocation issues; however experiments have shown that
4947 the vast majority of hoistable expressions are only movable
4948 from two successors, so raising this threshold is likely
4949 to nullify any benefit we get from code hoisting. */
4952 SET_BIT (hoist_exprs
[bb
->index
], i
);
4957 /* If we found nothing to hoist, then quit now. */
4964 /* Loop over all the hoistable expressions. */
4965 for (i
= 0; i
< hoist_exprs
[bb
->index
]->n_bits
; i
++)
4967 /* We want to insert the expression into BB only once, so
4968 note when we've inserted it. */
4969 insn_inserted_p
= 0;
4971 /* These tests should be the same as the tests above. */
4972 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
))
4974 /* We've found a potentially hoistable expression, now
4975 we look at every block BB dominates to see if it
4976 computes the expression. */
4977 for (j
= 0; j
< domby_len
; j
++)
4979 dominated
= domby
[j
];
4980 /* Ignore self dominance. */
4981 if (bb
== dominated
)
4984 /* We've found a dominated block, now see if it computes
4985 the busy expression and whether or not moving that
4986 expression to the "beginning" of that block is safe. */
4987 if (!TEST_BIT (antloc
[dominated
->index
], i
))
4990 /* The expression is computed in the dominated block and
4991 it would be safe to compute it at the start of the
4992 dominated block. Now we have to determine if the
4993 expression would reach the dominated block if it was
4994 placed at the end of BB. */
4995 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
4997 struct expr
*expr
= index_map
[i
];
4998 struct occr
*occr
= expr
->antic_occr
;
5002 /* Find the right occurrence of this expression. */
5003 while (BLOCK_FOR_INSN (occr
->insn
) != dominated
&& occr
)
5008 set
= single_set (insn
);
5011 /* Create a pseudo-reg to store the result of reaching
5012 expressions into. Get the mode for the new pseudo
5013 from the mode of the original destination pseudo. */
5014 if (expr
->reaching_reg
== NULL
)
5016 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
5018 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
5020 occr
->deleted_p
= 1;
5021 if (!insn_inserted_p
)
5023 insert_insn_end_bb (index_map
[i
], bb
, 0);
5024 insn_inserted_p
= 1;
5036 /* Top level routine to perform one code hoisting (aka unification) pass
5038 Return nonzero if a change was made. */
5041 one_code_hoisting_pass (void)
5045 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
5046 compute_hash_table (&expr_hash_table
);
5048 dump_hash_table (gcse_file
, "Code Hosting Expressions", &expr_hash_table
);
5050 if (expr_hash_table
.n_elems
> 0)
5052 alloc_code_hoist_mem (last_basic_block
, expr_hash_table
.n_elems
);
5053 compute_code_hoist_data ();
5055 free_code_hoist_mem ();
5058 free_hash_table (&expr_hash_table
);
5063 /* Here we provide the things required to do store motion towards
5064 the exit. In order for this to be effective, gcse also needed to
5065 be taught how to move a load when it is kill only by a store to itself.
5070 void foo(float scale)
5072 for (i=0; i<10; i++)
5076 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
5077 the load out since its live around the loop, and stored at the bottom
5080 The 'Load Motion' referred to and implemented in this file is
5081 an enhancement to gcse which when using edge based lcm, recognizes
5082 this situation and allows gcse to move the load out of the loop.
5084 Once gcse has hoisted the load, store motion can then push this
5085 load towards the exit, and we end up with no loads or stores of 'i'
5088 /* This will search the ldst list for a matching expression. If it
5089 doesn't find one, we create one and initialize it. */
5091 static struct ls_expr
*
5094 int do_not_record_p
= 0;
5095 struct ls_expr
* ptr
;
5098 hash
= hash_rtx (x
, GET_MODE (x
), &do_not_record_p
,
5099 NULL
, /*have_reg_qty=*/false);
5101 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
5102 if (ptr
->hash_index
== hash
&& expr_equiv_p (ptr
->pattern
, x
))
5105 ptr
= xmalloc (sizeof (struct ls_expr
));
5107 ptr
->next
= pre_ldst_mems
;
5110 ptr
->pattern_regs
= NULL_RTX
;
5111 ptr
->loads
= NULL_RTX
;
5112 ptr
->stores
= NULL_RTX
;
5113 ptr
->reaching_reg
= NULL_RTX
;
5116 ptr
->hash_index
= hash
;
5117 pre_ldst_mems
= ptr
;
5122 /* Free up an individual ldst entry. */
5125 free_ldst_entry (struct ls_expr
* ptr
)
5127 free_INSN_LIST_list (& ptr
->loads
);
5128 free_INSN_LIST_list (& ptr
->stores
);
5133 /* Free up all memory associated with the ldst list. */
5136 free_ldst_mems (void)
5138 while (pre_ldst_mems
)
5140 struct ls_expr
* tmp
= pre_ldst_mems
;
5142 pre_ldst_mems
= pre_ldst_mems
->next
;
5144 free_ldst_entry (tmp
);
5147 pre_ldst_mems
= NULL
;
5150 /* Dump debugging info about the ldst list. */
5153 print_ldst_list (FILE * file
)
5155 struct ls_expr
* ptr
;
5157 fprintf (file
, "LDST list: \n");
5159 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
5161 fprintf (file
, " Pattern (%3d): ", ptr
->index
);
5163 print_rtl (file
, ptr
->pattern
);
5165 fprintf (file
, "\n Loads : ");
5168 print_rtl (file
, ptr
->loads
);
5170 fprintf (file
, "(nil)");
5172 fprintf (file
, "\n Stores : ");
5175 print_rtl (file
, ptr
->stores
);
5177 fprintf (file
, "(nil)");
5179 fprintf (file
, "\n\n");
5182 fprintf (file
, "\n");
5185 /* Returns 1 if X is in the list of ldst only expressions. */
5187 static struct ls_expr
*
5188 find_rtx_in_ldst (rtx x
)
5190 struct ls_expr
* ptr
;
5192 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
5193 if (expr_equiv_p (ptr
->pattern
, x
) && ! ptr
->invalid
)
5199 /* Assign each element of the list of mems a monotonically increasing value. */
5202 enumerate_ldsts (void)
5204 struct ls_expr
* ptr
;
5207 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
5213 /* Return first item in the list. */
5215 static inline struct ls_expr
*
5216 first_ls_expr (void)
5218 return pre_ldst_mems
;
5221 /* Return the next item in the list after the specified one. */
5223 static inline struct ls_expr
*
5224 next_ls_expr (struct ls_expr
* ptr
)
5229 /* Load Motion for loads which only kill themselves. */
5231 /* Return true if x is a simple MEM operation, with no registers or
5232 side effects. These are the types of loads we consider for the
5233 ld_motion list, otherwise we let the usual aliasing take care of it. */
5241 if (MEM_VOLATILE_P (x
))
5244 if (GET_MODE (x
) == BLKmode
)
5247 /* If we are handling exceptions, we must be careful with memory references
5248 that may trap. If we are not, the behavior is undefined, so we may just
5250 if (flag_non_call_exceptions
&& may_trap_p (x
))
5253 if (side_effects_p (x
))
5256 /* Do not consider function arguments passed on stack. */
5257 if (reg_mentioned_p (stack_pointer_rtx
, x
))
5260 if (flag_float_store
&& FLOAT_MODE_P (GET_MODE (x
)))
5266 /* Make sure there isn't a buried reference in this pattern anywhere.
5267 If there is, invalidate the entry for it since we're not capable
5268 of fixing it up just yet.. We have to be sure we know about ALL
5269 loads since the aliasing code will allow all entries in the
5270 ld_motion list to not-alias itself. If we miss a load, we will get
5271 the wrong value since gcse might common it and we won't know to
5275 invalidate_any_buried_refs (rtx x
)
5279 struct ls_expr
* ptr
;
5281 /* Invalidate it in the list. */
5282 if (MEM_P (x
) && simple_mem (x
))
5284 ptr
= ldst_entry (x
);
5288 /* Recursively process the insn. */
5289 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
5291 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0; i
--)
5294 invalidate_any_buried_refs (XEXP (x
, i
));
5295 else if (fmt
[i
] == 'E')
5296 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5297 invalidate_any_buried_refs (XVECEXP (x
, i
, j
));
5301 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
5302 being defined as MEM loads and stores to symbols, with no side effects
5303 and no registers in the expression. For a MEM destination, we also
5304 check that the insn is still valid if we replace the destination with a
5305 REG, as is done in update_ld_motion_stores. If there are any uses/defs
5306 which don't match this criteria, they are invalidated and trimmed out
5310 compute_ld_motion_mems (void)
5312 struct ls_expr
* ptr
;
5316 pre_ldst_mems
= NULL
;
5320 for (insn
= BB_HEAD (bb
);
5321 insn
&& insn
!= NEXT_INSN (BB_END (bb
));
5322 insn
= NEXT_INSN (insn
))
5326 if (GET_CODE (PATTERN (insn
)) == SET
)
5328 rtx src
= SET_SRC (PATTERN (insn
));
5329 rtx dest
= SET_DEST (PATTERN (insn
));
5331 /* Check for a simple LOAD... */
5332 if (MEM_P (src
) && simple_mem (src
))
5334 ptr
= ldst_entry (src
);
5336 ptr
->loads
= alloc_INSN_LIST (insn
, ptr
->loads
);
5342 /* Make sure there isn't a buried load somewhere. */
5343 invalidate_any_buried_refs (src
);
5346 /* Check for stores. Don't worry about aliased ones, they
5347 will block any movement we might do later. We only care
5348 about this exact pattern since those are the only
5349 circumstance that we will ignore the aliasing info. */
5350 if (MEM_P (dest
) && simple_mem (dest
))
5352 ptr
= ldst_entry (dest
);
5355 && GET_CODE (src
) != ASM_OPERANDS
5356 /* Check for REG manually since want_to_gcse_p
5357 returns 0 for all REGs. */
5358 && can_assign_to_reg_p (src
))
5359 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
5365 invalidate_any_buried_refs (PATTERN (insn
));
5371 /* Remove any references that have been either invalidated or are not in the
5372 expression list for pre gcse. */
5375 trim_ld_motion_mems (void)
5377 struct ls_expr
* * last
= & pre_ldst_mems
;
5378 struct ls_expr
* ptr
= pre_ldst_mems
;
5384 /* Delete if entry has been made invalid. */
5387 /* Delete if we cannot find this mem in the expression list. */
5388 unsigned int hash
= ptr
->hash_index
% expr_hash_table
.size
;
5390 for (expr
= expr_hash_table
.table
[hash
];
5392 expr
= expr
->next_same_hash
)
5393 if (expr_equiv_p (expr
->expr
, ptr
->pattern
))
5397 expr
= (struct expr
*) 0;
5401 /* Set the expression field if we are keeping it. */
5409 free_ldst_entry (ptr
);
5414 /* Show the world what we've found. */
5415 if (gcse_file
&& pre_ldst_mems
!= NULL
)
5416 print_ldst_list (gcse_file
);
5419 /* This routine will take an expression which we are replacing with
5420 a reaching register, and update any stores that are needed if
5421 that expression is in the ld_motion list. Stores are updated by
5422 copying their SRC to the reaching register, and then storing
5423 the reaching register into the store location. These keeps the
5424 correct value in the reaching register for the loads. */
5427 update_ld_motion_stores (struct expr
* expr
)
5429 struct ls_expr
* mem_ptr
;
5431 if ((mem_ptr
= find_rtx_in_ldst (expr
->expr
)))
5433 /* We can try to find just the REACHED stores, but is shouldn't
5434 matter to set the reaching reg everywhere... some might be
5435 dead and should be eliminated later. */
5437 /* We replace (set mem expr) with (set reg expr) (set mem reg)
5438 where reg is the reaching reg used in the load. We checked in
5439 compute_ld_motion_mems that we can replace (set mem expr) with
5440 (set reg expr) in that insn. */
5441 rtx list
= mem_ptr
->stores
;
5443 for ( ; list
!= NULL_RTX
; list
= XEXP (list
, 1))
5445 rtx insn
= XEXP (list
, 0);
5446 rtx pat
= PATTERN (insn
);
5447 rtx src
= SET_SRC (pat
);
5448 rtx reg
= expr
->reaching_reg
;
5451 /* If we've already copied it, continue. */
5452 if (expr
->reaching_reg
== src
)
5457 fprintf (gcse_file
, "PRE: store updated with reaching reg ");
5458 print_rtl (gcse_file
, expr
->reaching_reg
);
5459 fprintf (gcse_file
, ":\n ");
5460 print_inline_rtx (gcse_file
, insn
, 8);
5461 fprintf (gcse_file
, "\n");
5464 copy
= gen_move_insn ( reg
, copy_rtx (SET_SRC (pat
)));
5465 new = emit_insn_before (copy
, insn
);
5466 record_one_set (REGNO (reg
), new);
5467 SET_SRC (pat
) = reg
;
5469 /* un-recognize this pattern since it's probably different now. */
5470 INSN_CODE (insn
) = -1;
5471 gcse_create_count
++;
5476 /* Store motion code. */
5478 #define ANTIC_STORE_LIST(x) ((x)->loads)
5479 #define AVAIL_STORE_LIST(x) ((x)->stores)
5480 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
5482 /* This is used to communicate the target bitvector we want to use in the
5483 reg_set_info routine when called via the note_stores mechanism. */
5484 static int * regvec
;
5486 /* And current insn, for the same routine. */
5487 static rtx compute_store_table_current_insn
;
5489 /* Used in computing the reverse edge graph bit vectors. */
5490 static sbitmap
* st_antloc
;
5492 /* Global holding the number of store expressions we are dealing with. */
5493 static int num_stores
;
5495 /* Checks to set if we need to mark a register set. Called from
5499 reg_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
,
5502 sbitmap bb_reg
= data
;
5504 if (GET_CODE (dest
) == SUBREG
)
5505 dest
= SUBREG_REG (dest
);
5509 regvec
[REGNO (dest
)] = INSN_UID (compute_store_table_current_insn
);
5511 SET_BIT (bb_reg
, REGNO (dest
));
5515 /* Clear any mark that says that this insn sets dest. Called from
5519 reg_clear_last_set (rtx dest
, rtx setter ATTRIBUTE_UNUSED
,
5522 int *dead_vec
= data
;
5524 if (GET_CODE (dest
) == SUBREG
)
5525 dest
= SUBREG_REG (dest
);
5528 dead_vec
[REGNO (dest
)] == INSN_UID (compute_store_table_current_insn
))
5529 dead_vec
[REGNO (dest
)] = 0;
5532 /* Return zero if some of the registers in list X are killed
5533 due to set of registers in bitmap REGS_SET. */
5536 store_ops_ok (rtx x
, int *regs_set
)
5540 for (; x
; x
= XEXP (x
, 1))
5543 if (regs_set
[REGNO(reg
)])
5550 /* Returns a list of registers mentioned in X. */
5552 extract_mentioned_regs (rtx x
)
5554 return extract_mentioned_regs_helper (x
, NULL_RTX
);
5557 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
5560 extract_mentioned_regs_helper (rtx x
, rtx accum
)
5566 /* Repeat is used to turn tail-recursion into iteration. */
5572 code
= GET_CODE (x
);
5576 return alloc_EXPR_LIST (0, x
, accum
);
5586 /* We do not run this function with arguments having side effects. */
5605 i
= GET_RTX_LENGTH (code
) - 1;
5606 fmt
= GET_RTX_FORMAT (code
);
5612 rtx tem
= XEXP (x
, i
);
5614 /* If we are about to do the last recursive call
5615 needed at this level, change it into iteration. */
5622 accum
= extract_mentioned_regs_helper (tem
, accum
);
5624 else if (fmt
[i
] == 'E')
5628 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
5629 accum
= extract_mentioned_regs_helper (XVECEXP (x
, i
, j
), accum
);
5636 /* Determine whether INSN is MEM store pattern that we will consider moving.
5637 REGS_SET_BEFORE is bitmap of registers set before (and including) the
5638 current insn, REGS_SET_AFTER is bitmap of registers set after (and
5639 including) the insn in this basic block. We must be passing through BB from
5640 head to end, as we are using this fact to speed things up.
5642 The results are stored this way:
5644 -- the first anticipatable expression is added into ANTIC_STORE_LIST
5645 -- if the processed expression is not anticipatable, NULL_RTX is added
5646 there instead, so that we can use it as indicator that no further
5647 expression of this type may be anticipatable
5648 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
5649 consequently, all of them but this head are dead and may be deleted.
5650 -- if the expression is not available, the insn due to that it fails to be
5651 available is stored in reaching_reg.
5653 The things are complicated a bit by fact that there already may be stores
5654 to the same MEM from other blocks; also caller must take care of the
5655 necessary cleanup of the temporary markers after end of the basic block.
5659 find_moveable_store (rtx insn
, int *regs_set_before
, int *regs_set_after
)
5661 struct ls_expr
* ptr
;
5663 int check_anticipatable
, check_available
;
5664 basic_block bb
= BLOCK_FOR_INSN (insn
);
5666 set
= single_set (insn
);
5670 dest
= SET_DEST (set
);
5672 if (! MEM_P (dest
) || MEM_VOLATILE_P (dest
)
5673 || GET_MODE (dest
) == BLKmode
)
5676 if (side_effects_p (dest
))
5679 /* If we are handling exceptions, we must be careful with memory references
5680 that may trap. If we are not, the behavior is undefined, so we may just
5682 if (flag_non_call_exceptions
&& may_trap_p (dest
))
5685 /* Even if the destination cannot trap, the source may. In this case we'd
5686 need to handle updating the REG_EH_REGION note. */
5687 if (find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
))
5690 ptr
= ldst_entry (dest
);
5691 if (!ptr
->pattern_regs
)
5692 ptr
->pattern_regs
= extract_mentioned_regs (dest
);
5694 /* Do not check for anticipatability if we either found one anticipatable
5695 store already, or tested for one and found out that it was killed. */
5696 check_anticipatable
= 0;
5697 if (!ANTIC_STORE_LIST (ptr
))
5698 check_anticipatable
= 1;
5701 tmp
= XEXP (ANTIC_STORE_LIST (ptr
), 0);
5703 && BLOCK_FOR_INSN (tmp
) != bb
)
5704 check_anticipatable
= 1;
5706 if (check_anticipatable
)
5708 if (store_killed_before (dest
, ptr
->pattern_regs
, insn
, bb
, regs_set_before
))
5712 ANTIC_STORE_LIST (ptr
) = alloc_INSN_LIST (tmp
,
5713 ANTIC_STORE_LIST (ptr
));
5716 /* It is not necessary to check whether store is available if we did
5717 it successfully before; if we failed before, do not bother to check
5718 until we reach the insn that caused us to fail. */
5719 check_available
= 0;
5720 if (!AVAIL_STORE_LIST (ptr
))
5721 check_available
= 1;
5724 tmp
= XEXP (AVAIL_STORE_LIST (ptr
), 0);
5725 if (BLOCK_FOR_INSN (tmp
) != bb
)
5726 check_available
= 1;
5728 if (check_available
)
5730 /* Check that we have already reached the insn at that the check
5731 failed last time. */
5732 if (LAST_AVAIL_CHECK_FAILURE (ptr
))
5734 for (tmp
= BB_END (bb
);
5735 tmp
!= insn
&& tmp
!= LAST_AVAIL_CHECK_FAILURE (ptr
);
5736 tmp
= PREV_INSN (tmp
))
5739 check_available
= 0;
5742 check_available
= store_killed_after (dest
, ptr
->pattern_regs
, insn
,
5744 &LAST_AVAIL_CHECK_FAILURE (ptr
));
5746 if (!check_available
)
5747 AVAIL_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
, AVAIL_STORE_LIST (ptr
));
5750 /* Find available and anticipatable stores. */
5753 compute_store_table (void)
5759 int *last_set_in
, *already_set
;
5760 struct ls_expr
* ptr
, **prev_next_ptr_ptr
;
5762 max_gcse_regno
= max_reg_num ();
5764 reg_set_in_block
= sbitmap_vector_alloc (last_basic_block
,
5766 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
5768 last_set_in
= xcalloc (max_gcse_regno
, sizeof (int));
5769 already_set
= xmalloc (sizeof (int) * max_gcse_regno
);
5771 /* Find all the stores we care about. */
5774 /* First compute the registers set in this block. */
5775 regvec
= last_set_in
;
5777 for (insn
= BB_HEAD (bb
);
5778 insn
!= NEXT_INSN (BB_END (bb
));
5779 insn
= NEXT_INSN (insn
))
5781 if (! INSN_P (insn
))
5786 bool clobbers_all
= false;
5787 #ifdef NON_SAVING_SETJMP
5788 if (NON_SAVING_SETJMP
5789 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
5790 clobbers_all
= true;
5793 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
5795 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
5797 last_set_in
[regno
] = INSN_UID (insn
);
5798 SET_BIT (reg_set_in_block
[bb
->index
], regno
);
5802 pat
= PATTERN (insn
);
5803 compute_store_table_current_insn
= insn
;
5804 note_stores (pat
, reg_set_info
, reg_set_in_block
[bb
->index
]);
5807 /* Now find the stores. */
5808 memset (already_set
, 0, sizeof (int) * max_gcse_regno
);
5809 regvec
= already_set
;
5810 for (insn
= BB_HEAD (bb
);
5811 insn
!= NEXT_INSN (BB_END (bb
));
5812 insn
= NEXT_INSN (insn
))
5814 if (! INSN_P (insn
))
5819 bool clobbers_all
= false;
5820 #ifdef NON_SAVING_SETJMP
5821 if (NON_SAVING_SETJMP
5822 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
5823 clobbers_all
= true;
5826 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
5828 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
5829 already_set
[regno
] = 1;
5832 pat
= PATTERN (insn
);
5833 note_stores (pat
, reg_set_info
, NULL
);
5835 /* Now that we've marked regs, look for stores. */
5836 find_moveable_store (insn
, already_set
, last_set_in
);
5838 /* Unmark regs that are no longer set. */
5839 compute_store_table_current_insn
= insn
;
5840 note_stores (pat
, reg_clear_last_set
, last_set_in
);
5843 bool clobbers_all
= false;
5844 #ifdef NON_SAVING_SETJMP
5845 if (NON_SAVING_SETJMP
5846 && find_reg_note (insn
, REG_SETJMP
, NULL_RTX
))
5847 clobbers_all
= true;
5850 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
5852 || TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
5853 && last_set_in
[regno
] == INSN_UID (insn
))
5854 last_set_in
[regno
] = 0;
5858 #ifdef ENABLE_CHECKING
5859 /* last_set_in should now be all-zero. */
5860 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
5861 gcc_assert (!last_set_in
[regno
]);
5864 /* Clear temporary marks. */
5865 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
5867 LAST_AVAIL_CHECK_FAILURE(ptr
) = NULL_RTX
;
5868 if (ANTIC_STORE_LIST (ptr
)
5869 && (tmp
= XEXP (ANTIC_STORE_LIST (ptr
), 0)) == NULL_RTX
)
5870 ANTIC_STORE_LIST (ptr
) = XEXP (ANTIC_STORE_LIST (ptr
), 1);
5874 /* Remove the stores that are not available anywhere, as there will
5875 be no opportunity to optimize them. */
5876 for (ptr
= pre_ldst_mems
, prev_next_ptr_ptr
= &pre_ldst_mems
;
5878 ptr
= *prev_next_ptr_ptr
)
5880 if (!AVAIL_STORE_LIST (ptr
))
5882 *prev_next_ptr_ptr
= ptr
->next
;
5883 free_ldst_entry (ptr
);
5886 prev_next_ptr_ptr
= &ptr
->next
;
5889 ret
= enumerate_ldsts ();
5893 fprintf (gcse_file
, "ST_avail and ST_antic (shown under loads..)\n");
5894 print_ldst_list (gcse_file
);
5902 /* Check to see if the load X is aliased with STORE_PATTERN.
5903 AFTER is true if we are checking the case when STORE_PATTERN occurs
5907 load_kills_store (rtx x
, rtx store_pattern
, int after
)
5910 return anti_dependence (x
, store_pattern
);
5912 return true_dependence (store_pattern
, GET_MODE (store_pattern
), x
,
5916 /* Go through the entire insn X, looking for any loads which might alias
5917 STORE_PATTERN. Return true if found.
5918 AFTER is true if we are checking the case when STORE_PATTERN occurs
5919 after the insn X. */
5922 find_loads (rtx x
, rtx store_pattern
, int after
)
5931 if (GET_CODE (x
) == SET
)
5936 if (load_kills_store (x
, store_pattern
, after
))
5940 /* Recursively process the insn. */
5941 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
5943 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0 && !ret
; i
--)
5946 ret
|= find_loads (XEXP (x
, i
), store_pattern
, after
);
5947 else if (fmt
[i
] == 'E')
5948 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5949 ret
|= find_loads (XVECEXP (x
, i
, j
), store_pattern
, after
);
5954 /* Check if INSN kills the store pattern X (is aliased with it).
5955 AFTER is true if we are checking the case when store X occurs
5956 after the insn. Return true if it it does. */
5959 store_killed_in_insn (rtx x
, rtx x_regs
, rtx insn
, int after
)
5961 rtx reg
, base
, note
;
5968 /* A normal or pure call might read from pattern,
5969 but a const call will not. */
5970 if (! CONST_OR_PURE_CALL_P (insn
) || pure_call_p (insn
))
5973 /* But even a const call reads its parameters. Check whether the
5974 base of some of registers used in mem is stack pointer. */
5975 for (reg
= x_regs
; reg
; reg
= XEXP (reg
, 1))
5977 base
= find_base_term (XEXP (reg
, 0));
5979 || (GET_CODE (base
) == ADDRESS
5980 && GET_MODE (base
) == Pmode
5981 && XEXP (base
, 0) == stack_pointer_rtx
))
5988 if (GET_CODE (PATTERN (insn
)) == SET
)
5990 rtx pat
= PATTERN (insn
);
5991 rtx dest
= SET_DEST (pat
);
5993 if (GET_CODE (dest
) == SIGN_EXTRACT
5994 || GET_CODE (dest
) == ZERO_EXTRACT
)
5995 dest
= XEXP (dest
, 0);
5997 /* Check for memory stores to aliased objects. */
5999 && !expr_equiv_p (dest
, x
))
6003 if (output_dependence (dest
, x
))
6008 if (output_dependence (x
, dest
))
6012 if (find_loads (SET_SRC (pat
), x
, after
))
6015 else if (find_loads (PATTERN (insn
), x
, after
))
6018 /* If this insn has a REG_EQUAL or REG_EQUIV note referencing a memory
6019 location aliased with X, then this insn kills X. */
6020 note
= find_reg_equal_equiv_note (insn
);
6023 note
= XEXP (note
, 0);
6025 /* However, if the note represents a must alias rather than a may
6026 alias relationship, then it does not kill X. */
6027 if (expr_equiv_p (note
, x
))
6030 /* See if there are any aliased loads in the note. */
6031 return find_loads (note
, x
, after
);
6034 /* Returns true if the expression X is loaded or clobbered on or after INSN
6035 within basic block BB. REGS_SET_AFTER is bitmap of registers set in
6036 or after the insn. X_REGS is list of registers mentioned in X. If the store
6037 is killed, return the last insn in that it occurs in FAIL_INSN. */
6040 store_killed_after (rtx x
, rtx x_regs
, rtx insn
, basic_block bb
,
6041 int *regs_set_after
, rtx
*fail_insn
)
6043 rtx last
= BB_END (bb
), act
;
6045 if (!store_ops_ok (x_regs
, regs_set_after
))
6047 /* We do not know where it will happen. */
6049 *fail_insn
= NULL_RTX
;
6053 /* Scan from the end, so that fail_insn is determined correctly. */
6054 for (act
= last
; act
!= PREV_INSN (insn
); act
= PREV_INSN (act
))
6055 if (store_killed_in_insn (x
, x_regs
, act
, false))
6065 /* Returns true if the expression X is loaded or clobbered on or before INSN
6066 within basic block BB. X_REGS is list of registers mentioned in X.
6067 REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
6069 store_killed_before (rtx x
, rtx x_regs
, rtx insn
, basic_block bb
,
6070 int *regs_set_before
)
6072 rtx first
= BB_HEAD (bb
);
6074 if (!store_ops_ok (x_regs
, regs_set_before
))
6077 for ( ; insn
!= PREV_INSN (first
); insn
= PREV_INSN (insn
))
6078 if (store_killed_in_insn (x
, x_regs
, insn
, true))
6084 /* Fill in available, anticipatable, transparent and kill vectors in
6085 STORE_DATA, based on lists of available and anticipatable stores. */
6087 build_store_vectors (void)
6090 int *regs_set_in_block
;
6092 struct ls_expr
* ptr
;
6095 /* Build the gen_vector. This is any store in the table which is not killed
6096 by aliasing later in its block. */
6097 ae_gen
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6098 sbitmap_vector_zero (ae_gen
, last_basic_block
);
6100 st_antloc
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6101 sbitmap_vector_zero (st_antloc
, last_basic_block
);
6103 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6105 for (st
= AVAIL_STORE_LIST (ptr
); st
!= NULL
; st
= XEXP (st
, 1))
6107 insn
= XEXP (st
, 0);
6108 bb
= BLOCK_FOR_INSN (insn
);
6110 /* If we've already seen an available expression in this block,
6111 we can delete this one (It occurs earlier in the block). We'll
6112 copy the SRC expression to an unused register in case there
6113 are any side effects. */
6114 if (TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
6116 rtx r
= gen_reg_rtx (GET_MODE (ptr
->pattern
));
6118 fprintf (gcse_file
, "Removing redundant store:\n");
6119 replace_store_insn (r
, XEXP (st
, 0), bb
, ptr
);
6122 SET_BIT (ae_gen
[bb
->index
], ptr
->index
);
6125 for (st
= ANTIC_STORE_LIST (ptr
); st
!= NULL
; st
= XEXP (st
, 1))
6127 insn
= XEXP (st
, 0);
6128 bb
= BLOCK_FOR_INSN (insn
);
6129 SET_BIT (st_antloc
[bb
->index
], ptr
->index
);
6133 ae_kill
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6134 sbitmap_vector_zero (ae_kill
, last_basic_block
);
6136 transp
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6137 sbitmap_vector_zero (transp
, last_basic_block
);
6138 regs_set_in_block
= xmalloc (sizeof (int) * max_gcse_regno
);
6142 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
6143 regs_set_in_block
[regno
] = TEST_BIT (reg_set_in_block
[bb
->index
], regno
);
6145 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6147 if (store_killed_after (ptr
->pattern
, ptr
->pattern_regs
, BB_HEAD (bb
),
6148 bb
, regs_set_in_block
, NULL
))
6150 /* It should not be necessary to consider the expression
6151 killed if it is both anticipatable and available. */
6152 if (!TEST_BIT (st_antloc
[bb
->index
], ptr
->index
)
6153 || !TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
6154 SET_BIT (ae_kill
[bb
->index
], ptr
->index
);
6157 SET_BIT (transp
[bb
->index
], ptr
->index
);
6161 free (regs_set_in_block
);
6165 dump_sbitmap_vector (gcse_file
, "st_antloc", "", st_antloc
, last_basic_block
);
6166 dump_sbitmap_vector (gcse_file
, "st_kill", "", ae_kill
, last_basic_block
);
6167 dump_sbitmap_vector (gcse_file
, "Transpt", "", transp
, last_basic_block
);
6168 dump_sbitmap_vector (gcse_file
, "st_avloc", "", ae_gen
, last_basic_block
);
6172 /* Insert an instruction at the beginning of a basic block, and update
6173 the BB_HEAD if needed. */
6176 insert_insn_start_bb (rtx insn
, basic_block bb
)
6178 /* Insert at start of successor block. */
6179 rtx prev
= PREV_INSN (BB_HEAD (bb
));
6180 rtx before
= BB_HEAD (bb
);
6183 if (! LABEL_P (before
)
6184 && (! NOTE_P (before
)
6185 || NOTE_LINE_NUMBER (before
) != NOTE_INSN_BASIC_BLOCK
))
6188 if (prev
== BB_END (bb
))
6190 before
= NEXT_INSN (before
);
6193 insn
= emit_insn_after (insn
, prev
);
6197 fprintf (gcse_file
, "STORE_MOTION insert store at start of BB %d:\n",
6199 print_inline_rtx (gcse_file
, insn
, 6);
6200 fprintf (gcse_file
, "\n");
6204 /* This routine will insert a store on an edge. EXPR is the ldst entry for
6205 the memory reference, and E is the edge to insert it on. Returns nonzero
6206 if an edge insertion was performed. */
6209 insert_store (struct ls_expr
* expr
, edge e
)
6216 /* We did all the deleted before this insert, so if we didn't delete a
6217 store, then we haven't set the reaching reg yet either. */
6218 if (expr
->reaching_reg
== NULL_RTX
)
6221 if (e
->flags
& EDGE_FAKE
)
6224 reg
= expr
->reaching_reg
;
6225 insn
= gen_move_insn (copy_rtx (expr
->pattern
), reg
);
6227 /* If we are inserting this expression on ALL predecessor edges of a BB,
6228 insert it at the start of the BB, and reset the insert bits on the other
6229 edges so we don't try to insert it on the other edges. */
6231 FOR_EACH_EDGE (tmp
, ei
, e
->dest
->preds
)
6232 if (!(tmp
->flags
& EDGE_FAKE
))
6234 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
6236 gcc_assert (index
!= EDGE_INDEX_NO_EDGE
);
6237 if (! TEST_BIT (pre_insert_map
[index
], expr
->index
))
6241 /* If tmp is NULL, we found an insertion on every edge, blank the
6242 insertion vector for these edges, and insert at the start of the BB. */
6243 if (!tmp
&& bb
!= EXIT_BLOCK_PTR
)
6245 FOR_EACH_EDGE (tmp
, ei
, e
->dest
->preds
)
6247 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
6248 RESET_BIT (pre_insert_map
[index
], expr
->index
);
6250 insert_insn_start_bb (insn
, bb
);
6254 /* We can't insert on this edge, so we'll insert at the head of the
6255 successors block. See Morgan, sec 10.5. */
6256 if ((e
->flags
& EDGE_ABNORMAL
) == EDGE_ABNORMAL
)
6258 insert_insn_start_bb (insn
, bb
);
6262 insert_insn_on_edge (insn
, e
);
6266 fprintf (gcse_file
, "STORE_MOTION insert insn on edge (%d, %d):\n",
6267 e
->src
->index
, e
->dest
->index
);
6268 print_inline_rtx (gcse_file
, insn
, 6);
6269 fprintf (gcse_file
, "\n");
6275 /* Remove any REG_EQUAL or REG_EQUIV notes containing a reference to the
6276 memory location in SMEXPR set in basic block BB.
6278 This could be rather expensive. */
6281 remove_reachable_equiv_notes (basic_block bb
, struct ls_expr
*smexpr
)
6283 edge_iterator
*stack
, ei
;
6286 sbitmap visited
= sbitmap_alloc (last_basic_block
);
6287 rtx last
, insn
, note
;
6288 rtx mem
= smexpr
->pattern
;
6290 stack
= xmalloc (sizeof (edge_iterator
) * n_basic_blocks
);
6292 ei
= ei_start (bb
->succs
);
6294 sbitmap_zero (visited
);
6296 act
= (EDGE_COUNT (ei
.container
) > 0 ? EDGE_I (ei
.container
, 0) : NULL
);
6304 sbitmap_free (visited
);
6307 act
= ei_edge (stack
[--sp
]);
6311 if (bb
== EXIT_BLOCK_PTR
6312 || TEST_BIT (visited
, bb
->index
))
6316 act
= (! ei_end_p (ei
)) ? ei_edge (ei
) : NULL
;
6319 SET_BIT (visited
, bb
->index
);
6321 if (TEST_BIT (st_antloc
[bb
->index
], smexpr
->index
))
6323 for (last
= ANTIC_STORE_LIST (smexpr
);
6324 BLOCK_FOR_INSN (XEXP (last
, 0)) != bb
;
6325 last
= XEXP (last
, 1))
6327 last
= XEXP (last
, 0);
6330 last
= NEXT_INSN (BB_END (bb
));
6332 for (insn
= BB_HEAD (bb
); insn
!= last
; insn
= NEXT_INSN (insn
))
6335 note
= find_reg_equal_equiv_note (insn
);
6336 if (!note
|| !expr_equiv_p (XEXP (note
, 0), mem
))
6340 fprintf (gcse_file
, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6342 remove_note (insn
, note
);
6347 act
= (! ei_end_p (ei
)) ? ei_edge (ei
) : NULL
;
6349 if (EDGE_COUNT (bb
->succs
) > 0)
6353 ei
= ei_start (bb
->succs
);
6354 act
= (EDGE_COUNT (ei
.container
) > 0 ? EDGE_I (ei
.container
, 0) : NULL
);
6359 /* This routine will replace a store with a SET to a specified register. */
6362 replace_store_insn (rtx reg
, rtx del
, basic_block bb
, struct ls_expr
*smexpr
)
6364 rtx insn
, mem
, note
, set
, ptr
, pair
;
6366 mem
= smexpr
->pattern
;
6367 insn
= gen_move_insn (reg
, SET_SRC (single_set (del
)));
6368 insn
= emit_insn_after (insn
, del
);
6373 "STORE_MOTION delete insn in BB %d:\n ", bb
->index
);
6374 print_inline_rtx (gcse_file
, del
, 6);
6375 fprintf (gcse_file
, "\nSTORE MOTION replaced with insn:\n ");
6376 print_inline_rtx (gcse_file
, insn
, 6);
6377 fprintf (gcse_file
, "\n");
6380 for (ptr
= ANTIC_STORE_LIST (smexpr
); ptr
; ptr
= XEXP (ptr
, 1))
6381 if (XEXP (ptr
, 0) == del
)
6383 XEXP (ptr
, 0) = insn
;
6387 /* Move the notes from the deleted insn to its replacement, and patch
6388 up the LIBCALL notes. */
6389 REG_NOTES (insn
) = REG_NOTES (del
);
6391 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
6394 pair
= XEXP (note
, 0);
6395 note
= find_reg_note (pair
, REG_LIBCALL
, NULL_RTX
);
6396 XEXP (note
, 0) = insn
;
6398 note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
6401 pair
= XEXP (note
, 0);
6402 note
= find_reg_note (pair
, REG_RETVAL
, NULL_RTX
);
6403 XEXP (note
, 0) = insn
;
6408 /* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
6409 they are no longer accurate provided that they are reached by this
6410 definition, so drop them. */
6411 for (; insn
!= NEXT_INSN (BB_END (bb
)); insn
= NEXT_INSN (insn
))
6414 set
= single_set (insn
);
6417 if (expr_equiv_p (SET_DEST (set
), mem
))
6419 note
= find_reg_equal_equiv_note (insn
);
6420 if (!note
|| !expr_equiv_p (XEXP (note
, 0), mem
))
6424 fprintf (gcse_file
, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6426 remove_note (insn
, note
);
6428 remove_reachable_equiv_notes (bb
, smexpr
);
6432 /* Delete a store, but copy the value that would have been stored into
6433 the reaching_reg for later storing. */
6436 delete_store (struct ls_expr
* expr
, basic_block bb
)
6440 if (expr
->reaching_reg
== NULL_RTX
)
6441 expr
->reaching_reg
= gen_reg_rtx (GET_MODE (expr
->pattern
));
6443 reg
= expr
->reaching_reg
;
6445 for (i
= AVAIL_STORE_LIST (expr
); i
; i
= XEXP (i
, 1))
6448 if (BLOCK_FOR_INSN (del
) == bb
)
6450 /* We know there is only one since we deleted redundant
6451 ones during the available computation. */
6452 replace_store_insn (reg
, del
, bb
, expr
);
6458 /* Free memory used by store motion. */
6461 free_store_memory (void)
6466 sbitmap_vector_free (ae_gen
);
6468 sbitmap_vector_free (ae_kill
);
6470 sbitmap_vector_free (transp
);
6472 sbitmap_vector_free (st_antloc
);
6474 sbitmap_vector_free (pre_insert_map
);
6476 sbitmap_vector_free (pre_delete_map
);
6477 if (reg_set_in_block
)
6478 sbitmap_vector_free (reg_set_in_block
);
6480 ae_gen
= ae_kill
= transp
= st_antloc
= NULL
;
6481 pre_insert_map
= pre_delete_map
= reg_set_in_block
= NULL
;
6484 /* Perform store motion. Much like gcse, except we move expressions the
6485 other way by looking at the flowgraph in reverse. */
6492 struct ls_expr
* ptr
;
6493 int update_flow
= 0;
6497 fprintf (gcse_file
, "before store motion\n");
6498 print_rtl (gcse_file
, get_insns ());
6501 init_alias_analysis ();
6503 /* Find all the available and anticipatable stores. */
6504 num_stores
= compute_store_table ();
6505 if (num_stores
== 0)
6507 sbitmap_vector_free (reg_set_in_block
);
6508 end_alias_analysis ();
6512 /* Now compute kill & transp vectors. */
6513 build_store_vectors ();
6514 add_noreturn_fake_exit_edges ();
6515 connect_infinite_loops_to_exit ();
6517 edge_list
= pre_edge_rev_lcm (gcse_file
, num_stores
, transp
, ae_gen
,
6518 st_antloc
, ae_kill
, &pre_insert_map
,
6521 /* Now we want to insert the new stores which are going to be needed. */
6522 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6525 if (TEST_BIT (pre_delete_map
[bb
->index
], ptr
->index
))
6526 delete_store (ptr
, bb
);
6528 for (x
= 0; x
< NUM_EDGES (edge_list
); x
++)
6529 if (TEST_BIT (pre_insert_map
[x
], ptr
->index
))
6530 update_flow
|= insert_store (ptr
, INDEX_EDGE (edge_list
, x
));
6534 commit_edge_insertions ();
6536 free_store_memory ();
6537 free_edge_list (edge_list
);
6538 remove_fake_exit_edges ();
6539 end_alias_analysis ();
6543 /* Entry point for jump bypassing optimization pass. */
6546 bypass_jumps (FILE *file
)
6550 /* We do not construct an accurate cfg in functions which call
6551 setjmp, so just punt to be safe. */
6552 if (current_function_calls_setjmp
)
6555 /* For calling dump_foo fns from gdb. */
6556 debug_stderr
= stderr
;
6559 /* Identify the basic block information for this function, including
6560 successors and predecessors. */
6561 max_gcse_regno
= max_reg_num ();
6564 dump_flow_info (file
);
6566 /* Return if there's nothing to do, or it is too expensive. */
6567 if (n_basic_blocks
<= 1 || is_too_expensive (_ ("jump bypassing disabled")))
6570 gcc_obstack_init (&gcse_obstack
);
6573 /* We need alias. */
6574 init_alias_analysis ();
6576 /* Record where pseudo-registers are set. This data is kept accurate
6577 during each pass. ??? We could also record hard-reg information here
6578 [since it's unchanging], however it is currently done during hash table
6581 It may be tempting to compute MEM set information here too, but MEM sets
6582 will be subject to code motion one day and thus we need to compute
6583 information about memory sets when we build the hash tables. */
6585 alloc_reg_set_mem (max_gcse_regno
);
6586 compute_sets (get_insns ());
6588 max_gcse_regno
= max_reg_num ();
6589 alloc_gcse_mem (get_insns ());
6590 changed
= one_cprop_pass (MAX_GCSE_PASSES
+ 2, 1, 1);
6595 fprintf (file
, "BYPASS of %s: %d basic blocks, ",
6596 current_function_name (), n_basic_blocks
);
6597 fprintf (file
, "%d bytes\n\n", bytes_used
);
6600 obstack_free (&gcse_obstack
, NULL
);
6601 free_reg_set_mem ();
6603 /* We are finished with alias. */
6604 end_alias_analysis ();
6605 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
6610 /* Return true if the graph is too expensive to optimize. PASS is the
6611 optimization about to be performed. */
6614 is_too_expensive (const char *pass
)
6616 /* Trying to perform global optimizations on flow graphs which have
6617 a high connectivity will take a long time and is unlikely to be
6618 particularly useful.
6620 In normal circumstances a cfg should have about twice as many
6621 edges as blocks. But we do not want to punish small functions
6622 which have a couple switch statements. Rather than simply
6623 threshold the number of blocks, uses something with a more
6624 graceful degradation. */
6625 if (n_edges
> 20000 + n_basic_blocks
* 4)
6627 if (warn_disabled_optimization
)
6628 warning ("%s: %d basic blocks and %d edges/basic block",
6629 pass
, n_basic_blocks
, n_edges
/ n_basic_blocks
);
6634 /* If allocating memory for the cprop bitmap would take up too much
6635 storage it's better just to disable the optimization. */
6637 * SBITMAP_SET_SIZE (max_reg_num ())
6638 * sizeof (SBITMAP_ELT_TYPE
)) > MAX_GCSE_MEMORY
)
6640 if (warn_disabled_optimization
)
6641 warning ("%s: %d basic blocks and %d registers",
6642 pass
, n_basic_blocks
, max_reg_num ());
6650 #include "gt-gcse.h"