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, 2005
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 static void compute_can_copy (void);
529 static void *gmalloc (size_t) ATTRIBUTE_MALLOC
;
530 static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC
;
531 static void *grealloc (void *, size_t);
532 static void *gcse_alloc (unsigned long);
533 static void alloc_gcse_mem (rtx
);
534 static void free_gcse_mem (void);
535 static void alloc_reg_set_mem (int);
536 static void free_reg_set_mem (void);
537 static void record_one_set (int, rtx
);
538 static void replace_one_set (int, rtx
, rtx
);
539 static void record_set_info (rtx
, rtx
, void *);
540 static void compute_sets (rtx
);
541 static void hash_scan_insn (rtx
, struct hash_table
*, int);
542 static void hash_scan_set (rtx
, rtx
, struct hash_table
*);
543 static void hash_scan_clobber (rtx
, rtx
, struct hash_table
*);
544 static void hash_scan_call (rtx
, rtx
, struct hash_table
*);
545 static int want_to_gcse_p (rtx
);
546 static bool can_assign_to_reg_p (rtx
);
547 static bool gcse_constant_p (rtx
);
548 static int oprs_unchanged_p (rtx
, rtx
, int);
549 static int oprs_anticipatable_p (rtx
, rtx
);
550 static int oprs_available_p (rtx
, rtx
);
551 static void insert_expr_in_table (rtx
, enum machine_mode
, rtx
, int, int,
552 struct hash_table
*);
553 static void insert_set_in_table (rtx
, rtx
, struct hash_table
*);
554 static unsigned int hash_expr (rtx
, enum machine_mode
, int *, int);
555 static unsigned int hash_set (int, int);
556 static int expr_equiv_p (rtx
, rtx
);
557 static void record_last_reg_set_info (rtx
, int);
558 static void record_last_mem_set_info (rtx
);
559 static void record_last_set_info (rtx
, rtx
, void *);
560 static void compute_hash_table (struct hash_table
*);
561 static void alloc_hash_table (int, struct hash_table
*, int);
562 static void free_hash_table (struct hash_table
*);
563 static void compute_hash_table_work (struct hash_table
*);
564 static void dump_hash_table (FILE *, const char *, struct hash_table
*);
565 static struct expr
*lookup_set (unsigned int, struct hash_table
*);
566 static struct expr
*next_set (unsigned int, struct expr
*);
567 static void reset_opr_set_tables (void);
568 static int oprs_not_set_p (rtx
, rtx
);
569 static void mark_call (rtx
);
570 static void mark_set (rtx
, rtx
);
571 static void mark_clobber (rtx
, rtx
);
572 static void mark_oprs_set (rtx
);
573 static void alloc_cprop_mem (int, int);
574 static void free_cprop_mem (void);
575 static void compute_transp (rtx
, int, sbitmap
*, int);
576 static void compute_transpout (void);
577 static void compute_local_properties (sbitmap
*, sbitmap
*, sbitmap
*,
578 struct hash_table
*);
579 static void compute_cprop_data (void);
580 static void find_used_regs (rtx
*, void *);
581 static int try_replace_reg (rtx
, rtx
, rtx
);
582 static struct expr
*find_avail_set (int, rtx
);
583 static int cprop_jump (basic_block
, rtx
, rtx
, rtx
, rtx
);
584 static void mems_conflict_for_gcse_p (rtx
, rtx
, void *);
585 static int load_killed_in_block_p (basic_block
, int, rtx
, int);
586 static void canon_list_insert (rtx
, rtx
, void *);
587 static int cprop_insn (rtx
, int);
588 static int cprop (int);
589 static void find_implicit_sets (void);
590 static int one_cprop_pass (int, int, int);
591 static bool constprop_register (rtx
, rtx
, rtx
, int);
592 static struct expr
*find_bypass_set (int, int);
593 static bool reg_killed_on_edge (rtx
, edge
);
594 static int bypass_block (basic_block
, rtx
, rtx
);
595 static int bypass_conditional_jumps (void);
596 static void alloc_pre_mem (int, int);
597 static void free_pre_mem (void);
598 static void compute_pre_data (void);
599 static int pre_expr_reaches_here_p (basic_block
, struct expr
*,
601 static void insert_insn_end_bb (struct expr
*, basic_block
, int);
602 static void pre_insert_copy_insn (struct expr
*, rtx
);
603 static void pre_insert_copies (void);
604 static int pre_delete (void);
605 static int pre_gcse (void);
606 static int one_pre_gcse_pass (int);
607 static void add_label_notes (rtx
, rtx
);
608 static void alloc_code_hoist_mem (int, int);
609 static void free_code_hoist_mem (void);
610 static void compute_code_hoist_vbeinout (void);
611 static void compute_code_hoist_data (void);
612 static int hoist_expr_reaches_here_p (basic_block
, int, basic_block
, char *);
613 static void hoist_code (void);
614 static int one_code_hoisting_pass (void);
615 static rtx
process_insert_insn (struct expr
*);
616 static int pre_edge_insert (struct edge_list
*, struct expr
**);
617 static int pre_expr_reaches_here_p_work (basic_block
, struct expr
*,
618 basic_block
, char *);
619 static struct ls_expr
* ldst_entry (rtx
);
620 static void free_ldst_entry (struct ls_expr
*);
621 static void free_ldst_mems (void);
622 static void print_ldst_list (FILE *);
623 static struct ls_expr
* find_rtx_in_ldst (rtx
);
624 static int enumerate_ldsts (void);
625 static inline struct ls_expr
* first_ls_expr (void);
626 static inline struct ls_expr
* next_ls_expr (struct ls_expr
*);
627 static int simple_mem (rtx
);
628 static void invalidate_any_buried_refs (rtx
);
629 static void compute_ld_motion_mems (void);
630 static void trim_ld_motion_mems (void);
631 static void update_ld_motion_stores (struct expr
*);
632 static void reg_set_info (rtx
, rtx
, void *);
633 static void reg_clear_last_set (rtx
, rtx
, void *);
634 static bool store_ops_ok (rtx
, int *);
635 static rtx
extract_mentioned_regs (rtx
);
636 static rtx
extract_mentioned_regs_helper (rtx
, rtx
);
637 static void find_moveable_store (rtx
, int *, int *);
638 static int compute_store_table (void);
639 static bool load_kills_store (rtx
, rtx
, int);
640 static bool find_loads (rtx
, rtx
, int);
641 static bool store_killed_in_insn (rtx
, rtx
, rtx
, int);
642 static bool store_killed_after (rtx
, rtx
, rtx
, basic_block
, int *, rtx
*);
643 static bool store_killed_before (rtx
, rtx
, rtx
, basic_block
, int *);
644 static void build_store_vectors (void);
645 static void insert_insn_start_bb (rtx
, basic_block
);
646 static int insert_store (struct ls_expr
*, edge
);
647 static void remove_reachable_equiv_notes (basic_block
, struct ls_expr
*);
648 static void replace_store_insn (rtx
, rtx
, basic_block
, struct ls_expr
*);
649 static void delete_store (struct ls_expr
*, basic_block
);
650 static void free_store_memory (void);
651 static void store_motion (void);
652 static void free_insn_expr_list_list (rtx
*);
653 static void clear_modify_mem_tables (void);
654 static void free_modify_mem_tables (void);
655 static rtx
gcse_emit_move_after (rtx
, rtx
, rtx
);
656 static void local_cprop_find_used_regs (rtx
*, void *);
657 static bool do_local_cprop (rtx
, rtx
, int, rtx
*);
658 static bool adjust_libcall_notes (rtx
, rtx
, rtx
, rtx
*);
659 static void local_cprop_pass (int);
660 static bool is_too_expensive (const char *);
663 /* Entry point for global common subexpression elimination.
664 F is the first instruction in the function. Return nonzero if a
668 gcse_main (rtx f
, FILE *file
)
671 /* Bytes used at start of pass. */
672 int initial_bytes_used
;
673 /* Maximum number of bytes used by a pass. */
675 /* Point to release obstack data from for each pass. */
676 char *gcse_obstack_bottom
;
678 /* We do not construct an accurate cfg in functions which call
679 setjmp, so just punt to be safe. */
680 if (current_function_calls_setjmp
)
683 /* Assume that we do not need to run jump optimizations after gcse. */
684 run_jump_opt_after_gcse
= 0;
686 /* For calling dump_foo fns from gdb. */
687 debug_stderr
= stderr
;
690 /* Identify the basic block information for this function, including
691 successors and predecessors. */
692 max_gcse_regno
= max_reg_num ();
695 dump_flow_info (file
);
697 /* Return if there's nothing to do, or it is too expensive. */
698 if (n_basic_blocks
<= 1 || is_too_expensive (_("GCSE disabled")))
701 gcc_obstack_init (&gcse_obstack
);
705 init_alias_analysis ();
706 /* Record where pseudo-registers are set. This data is kept accurate
707 during each pass. ??? We could also record hard-reg information here
708 [since it's unchanging], however it is currently done during hash table
711 It may be tempting to compute MEM set information here too, but MEM sets
712 will be subject to code motion one day and thus we need to compute
713 information about memory sets when we build the hash tables. */
715 alloc_reg_set_mem (max_gcse_regno
);
719 initial_bytes_used
= bytes_used
;
721 gcse_obstack_bottom
= gcse_alloc (1);
723 while (changed
&& pass
< MAX_GCSE_PASSES
)
727 fprintf (file
, "GCSE pass %d\n\n", pass
+ 1);
729 /* Initialize bytes_used to the space for the pred/succ lists,
730 and the reg_set_table data. */
731 bytes_used
= initial_bytes_used
;
733 /* Each pass may create new registers, so recalculate each time. */
734 max_gcse_regno
= max_reg_num ();
738 /* Don't allow constant propagation to modify jumps
740 timevar_push (TV_CPROP1
);
741 changed
= one_cprop_pass (pass
+ 1, 0, 0);
742 timevar_pop (TV_CPROP1
);
748 timevar_push (TV_PRE
);
749 changed
|= one_pre_gcse_pass (pass
+ 1);
750 /* We may have just created new basic blocks. Release and
751 recompute various things which are sized on the number of
755 free_modify_mem_tables ();
756 modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
757 canon_modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
760 alloc_reg_set_mem (max_reg_num ());
762 run_jump_opt_after_gcse
= 1;
763 timevar_pop (TV_PRE
);
766 if (max_pass_bytes
< bytes_used
)
767 max_pass_bytes
= bytes_used
;
769 /* Free up memory, then reallocate for code hoisting. We can
770 not re-use the existing allocated memory because the tables
771 will not have info for the insns or registers created by
772 partial redundancy elimination. */
775 /* It does not make sense to run code hoisting unless we are optimizing
776 for code size -- it rarely makes programs faster, and can make
777 them bigger if we did partial redundancy elimination (when optimizing
778 for space, we don't run the partial redundancy algorithms). */
781 timevar_push (TV_HOIST
);
782 max_gcse_regno
= max_reg_num ();
784 changed
|= one_code_hoisting_pass ();
787 if (max_pass_bytes
< bytes_used
)
788 max_pass_bytes
= bytes_used
;
789 timevar_pop (TV_HOIST
);
794 fprintf (file
, "\n");
798 obstack_free (&gcse_obstack
, gcse_obstack_bottom
);
802 /* Do one last pass of copy propagation, including cprop into
803 conditional jumps. */
805 max_gcse_regno
= max_reg_num ();
807 /* This time, go ahead and allow cprop to alter jumps. */
808 timevar_push (TV_CPROP2
);
809 one_cprop_pass (pass
+ 1, 1, 0);
810 timevar_pop (TV_CPROP2
);
815 fprintf (file
, "GCSE of %s: %d basic blocks, ",
816 current_function_name (), n_basic_blocks
);
817 fprintf (file
, "%d pass%s, %d bytes\n\n",
818 pass
, pass
> 1 ? "es" : "", max_pass_bytes
);
821 obstack_free (&gcse_obstack
, NULL
);
824 /* We are finished with alias. */
825 end_alias_analysis ();
826 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
828 if (!optimize_size
&& flag_gcse_sm
)
830 timevar_push (TV_LSM
);
832 timevar_pop (TV_LSM
);
835 /* Record where pseudo-registers are set. */
836 return run_jump_opt_after_gcse
;
839 /* Misc. utilities. */
841 /* Nonzero for each mode that supports (set (reg) (reg)).
842 This is trivially true for integer and floating point values.
843 It may or may not be true for condition codes. */
844 static char can_copy
[(int) NUM_MACHINE_MODES
];
846 /* Compute which modes support reg/reg copy operations. */
849 compute_can_copy (void)
852 #ifndef AVOID_CCMODE_COPIES
855 memset (can_copy
, 0, NUM_MACHINE_MODES
);
858 for (i
= 0; i
< NUM_MACHINE_MODES
; i
++)
859 if (GET_MODE_CLASS (i
) == MODE_CC
)
861 #ifdef AVOID_CCMODE_COPIES
864 reg
= gen_rtx_REG ((enum machine_mode
) i
, LAST_VIRTUAL_REGISTER
+ 1);
865 insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, reg
));
866 if (recog (PATTERN (insn
), insn
, NULL
) >= 0)
876 /* Returns whether the mode supports reg/reg copy operations. */
879 can_copy_p (enum machine_mode mode
)
881 static bool can_copy_init_p
= false;
883 if (! can_copy_init_p
)
886 can_copy_init_p
= true;
889 return can_copy
[mode
] != 0;
892 /* Cover function to xmalloc to record bytes allocated. */
895 gmalloc (size_t size
)
898 return xmalloc (size
);
901 /* Cover function to xcalloc to record bytes allocated. */
904 gcalloc (size_t nelem
, size_t elsize
)
906 bytes_used
+= nelem
* elsize
;
907 return xcalloc (nelem
, elsize
);
910 /* Cover function to xrealloc.
911 We don't record the additional size since we don't know it.
912 It won't affect memory usage stats much anyway. */
915 grealloc (void *ptr
, size_t size
)
917 return xrealloc (ptr
, size
);
920 /* Cover function to obstack_alloc. */
923 gcse_alloc (unsigned long size
)
926 return obstack_alloc (&gcse_obstack
, size
);
929 /* Allocate memory for the cuid mapping array,
930 and reg/memory set tracking tables.
932 This is called at the start of each pass. */
935 alloc_gcse_mem (rtx f
)
940 /* Find the largest UID and create a mapping from UIDs to CUIDs.
941 CUIDs are like UIDs except they increase monotonically, have no gaps,
942 and only apply to real insns. */
944 max_uid
= get_max_uid ();
945 uid_cuid
= gcalloc (max_uid
+ 1, sizeof (int));
946 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
949 uid_cuid
[INSN_UID (insn
)] = i
++;
951 uid_cuid
[INSN_UID (insn
)] = i
;
954 /* Create a table mapping cuids to insns. */
957 cuid_insn
= gcalloc (max_cuid
+ 1, sizeof (rtx
));
958 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
960 CUID_INSN (i
++) = insn
;
962 /* Allocate vars to track sets of regs. */
963 reg_set_bitmap
= BITMAP_XMALLOC ();
965 /* Allocate vars to track sets of regs, memory per block. */
966 reg_set_in_block
= sbitmap_vector_alloc (last_basic_block
, max_gcse_regno
);
967 /* Allocate array to keep a list of insns which modify memory in each
969 modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
970 canon_modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
971 modify_mem_list_set
= BITMAP_XMALLOC ();
972 canon_modify_mem_list_set
= BITMAP_XMALLOC ();
975 /* Free memory allocated by alloc_gcse_mem. */
983 BITMAP_XFREE (reg_set_bitmap
);
985 sbitmap_vector_free (reg_set_in_block
);
986 free_modify_mem_tables ();
987 BITMAP_XFREE (modify_mem_list_set
);
988 BITMAP_XFREE (canon_modify_mem_list_set
);
991 /* Compute the local properties of each recorded expression.
993 Local properties are those that are defined by the block, irrespective of
996 An expression is transparent in a block if its operands are not modified
999 An expression is computed (locally available) in a block if it is computed
1000 at least once and expression would contain the same value if the
1001 computation was moved to the end of the block.
1003 An expression is locally anticipatable in a block if it is computed at
1004 least once and expression would contain the same value if the computation
1005 was moved to the beginning of the block.
1007 We call this routine for cprop, pre and code hoisting. They all compute
1008 basically the same information and thus can easily share this code.
1010 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1011 properties. If NULL, then it is not necessary to compute or record that
1012 particular property.
1014 TABLE controls which hash table to look at. If it is set hash table,
1015 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1019 compute_local_properties (sbitmap
*transp
, sbitmap
*comp
, sbitmap
*antloc
,
1020 struct hash_table
*table
)
1024 /* Initialize any bitmaps that were passed in. */
1028 sbitmap_vector_zero (transp
, last_basic_block
);
1030 sbitmap_vector_ones (transp
, last_basic_block
);
1034 sbitmap_vector_zero (comp
, last_basic_block
);
1036 sbitmap_vector_zero (antloc
, last_basic_block
);
1038 for (i
= 0; i
< table
->size
; i
++)
1042 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1044 int indx
= expr
->bitmap_index
;
1047 /* The expression is transparent in this block if it is not killed.
1048 We start by assuming all are transparent [none are killed], and
1049 then reset the bits for those that are. */
1051 compute_transp (expr
->expr
, indx
, transp
, table
->set_p
);
1053 /* The occurrences recorded in antic_occr are exactly those that
1054 we want to set to nonzero in ANTLOC. */
1056 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
1058 SET_BIT (antloc
[BLOCK_NUM (occr
->insn
)], indx
);
1060 /* While we're scanning the table, this is a good place to
1062 occr
->deleted_p
= 0;
1065 /* The occurrences recorded in avail_occr are exactly those that
1066 we want to set to nonzero in COMP. */
1068 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
1070 SET_BIT (comp
[BLOCK_NUM (occr
->insn
)], indx
);
1072 /* While we're scanning the table, this is a good place to
1077 /* While we're scanning the table, this is a good place to
1079 expr
->reaching_reg
= 0;
1084 /* Register set information.
1086 `reg_set_table' records where each register is set or otherwise
1089 static struct obstack reg_set_obstack
;
1092 alloc_reg_set_mem (int n_regs
)
1094 reg_set_table_size
= n_regs
+ REG_SET_TABLE_SLOP
;
1095 reg_set_table
= gcalloc (reg_set_table_size
, sizeof (struct reg_set
*));
1097 gcc_obstack_init (®_set_obstack
);
1101 free_reg_set_mem (void)
1103 free (reg_set_table
);
1104 obstack_free (®_set_obstack
, NULL
);
1107 /* An OLD_INSN that used to set REGNO was replaced by NEW_INSN.
1108 Update the corresponding `reg_set_table' entry accordingly.
1109 We assume that NEW_INSN is not already recorded in reg_set_table[regno]. */
1112 replace_one_set (int regno
, rtx old_insn
, rtx new_insn
)
1114 struct reg_set
*reg_info
;
1115 if (regno
>= reg_set_table_size
)
1117 for (reg_info
= reg_set_table
[regno
]; reg_info
; reg_info
= reg_info
->next
)
1118 if (reg_info
->insn
== old_insn
)
1120 reg_info
->insn
= new_insn
;
1125 /* Record REGNO in the reg_set table. */
1128 record_one_set (int regno
, rtx insn
)
1130 /* Allocate a new reg_set element and link it onto the list. */
1131 struct reg_set
*new_reg_info
;
1133 /* If the table isn't big enough, enlarge it. */
1134 if (regno
>= reg_set_table_size
)
1136 int new_size
= regno
+ REG_SET_TABLE_SLOP
;
1138 reg_set_table
= grealloc (reg_set_table
,
1139 new_size
* sizeof (struct reg_set
*));
1140 memset (reg_set_table
+ reg_set_table_size
, 0,
1141 (new_size
- reg_set_table_size
) * sizeof (struct reg_set
*));
1142 reg_set_table_size
= new_size
;
1145 new_reg_info
= obstack_alloc (®_set_obstack
, sizeof (struct reg_set
));
1146 bytes_used
+= sizeof (struct reg_set
);
1147 new_reg_info
->insn
= insn
;
1148 new_reg_info
->next
= reg_set_table
[regno
];
1149 reg_set_table
[regno
] = new_reg_info
;
1152 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1153 an insn. The DATA is really the instruction in which the SET is
1157 record_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
, void *data
)
1159 rtx record_set_insn
= (rtx
) data
;
1161 if (REG_P (dest
) && REGNO (dest
) >= FIRST_PSEUDO_REGISTER
)
1162 record_one_set (REGNO (dest
), record_set_insn
);
1165 /* Scan the function and record each set of each pseudo-register.
1167 This is called once, at the start of the gcse pass. See the comments for
1168 `reg_set_table' for further documentation. */
1171 compute_sets (rtx f
)
1175 for (insn
= f
; insn
!= 0; insn
= NEXT_INSN (insn
))
1177 note_stores (PATTERN (insn
), record_set_info
, insn
);
1180 /* Hash table support. */
1182 struct reg_avail_info
1184 basic_block last_bb
;
1189 static struct reg_avail_info
*reg_avail_info
;
1190 static basic_block current_bb
;
1193 /* See whether X, the source of a set, is something we want to consider for
1197 want_to_gcse_p (rtx x
)
1199 switch (GET_CODE (x
))
1210 return can_assign_to_reg_p (x
);
1214 /* Used internally by can_assign_to_reg_p. */
1216 static GTY(()) rtx test_insn
;
1218 /* Return true if we can assign X to a pseudo register. */
1221 can_assign_to_reg_p (rtx x
)
1223 int num_clobbers
= 0;
1226 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1227 if (general_operand (x
, GET_MODE (x
)))
1229 else if (GET_MODE (x
) == VOIDmode
)
1232 /* Otherwise, check if we can make a valid insn from it. First initialize
1233 our test insn if we haven't already. */
1237 = make_insn_raw (gen_rtx_SET (VOIDmode
,
1238 gen_rtx_REG (word_mode
,
1239 FIRST_PSEUDO_REGISTER
* 2),
1241 NEXT_INSN (test_insn
) = PREV_INSN (test_insn
) = 0;
1244 /* Now make an insn like the one we would make when GCSE'ing and see if
1246 PUT_MODE (SET_DEST (PATTERN (test_insn
)), GET_MODE (x
));
1247 SET_SRC (PATTERN (test_insn
)) = x
;
1248 return ((icode
= recog (PATTERN (test_insn
), test_insn
, &num_clobbers
)) >= 0
1249 && (num_clobbers
== 0 || ! added_clobbers_hard_reg_p (icode
)));
1252 /* Return nonzero if the operands of expression X are unchanged from the
1253 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1254 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1257 oprs_unchanged_p (rtx x
, rtx insn
, int avail_p
)
1266 code
= GET_CODE (x
);
1271 struct reg_avail_info
*info
= ®_avail_info
[REGNO (x
)];
1273 if (info
->last_bb
!= current_bb
)
1276 return info
->last_set
< INSN_CUID (insn
);
1278 return info
->first_set
>= INSN_CUID (insn
);
1282 if (load_killed_in_block_p (current_bb
, INSN_CUID (insn
),
1286 return oprs_unchanged_p (XEXP (x
, 0), insn
, avail_p
);
1312 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1316 /* If we are about to do the last recursive call needed at this
1317 level, change it into iteration. This function is called enough
1320 return oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
);
1322 else if (! oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
))
1325 else if (fmt
[i
] == 'E')
1326 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1327 if (! oprs_unchanged_p (XVECEXP (x
, i
, j
), insn
, avail_p
))
1334 /* Used for communication between mems_conflict_for_gcse_p and
1335 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1336 conflict between two memory references. */
1337 static int gcse_mems_conflict_p
;
1339 /* Used for communication between mems_conflict_for_gcse_p and
1340 load_killed_in_block_p. A memory reference for a load instruction,
1341 mems_conflict_for_gcse_p will see if a memory store conflicts with
1342 this memory load. */
1343 static rtx gcse_mem_operand
;
1345 /* DEST is the output of an instruction. If it is a memory reference, and
1346 possibly conflicts with the load found in gcse_mem_operand, then set
1347 gcse_mems_conflict_p to a nonzero value. */
1350 mems_conflict_for_gcse_p (rtx dest
, rtx setter ATTRIBUTE_UNUSED
,
1351 void *data ATTRIBUTE_UNUSED
)
1353 while (GET_CODE (dest
) == SUBREG
1354 || GET_CODE (dest
) == ZERO_EXTRACT
1355 || GET_CODE (dest
) == STRICT_LOW_PART
)
1356 dest
= XEXP (dest
, 0);
1358 /* If DEST is not a MEM, then it will not conflict with the load. Note
1359 that function calls are assumed to clobber memory, but are handled
1364 /* If we are setting a MEM in our list of specially recognized MEMs,
1365 don't mark as killed this time. */
1367 if (expr_equiv_p (dest
, gcse_mem_operand
) && pre_ldst_mems
!= NULL
)
1369 if (!find_rtx_in_ldst (dest
))
1370 gcse_mems_conflict_p
= 1;
1374 if (true_dependence (dest
, GET_MODE (dest
), gcse_mem_operand
,
1376 gcse_mems_conflict_p
= 1;
1379 /* Return nonzero if the expression in X (a memory reference) is killed
1380 in block BB before or after the insn with the CUID in UID_LIMIT.
1381 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1384 To check the entire block, set UID_LIMIT to max_uid + 1 and
1388 load_killed_in_block_p (basic_block bb
, int uid_limit
, rtx x
, int avail_p
)
1390 rtx list_entry
= modify_mem_list
[bb
->index
];
1394 /* Ignore entries in the list that do not apply. */
1396 && INSN_CUID (XEXP (list_entry
, 0)) < uid_limit
)
1398 && INSN_CUID (XEXP (list_entry
, 0)) > uid_limit
))
1400 list_entry
= XEXP (list_entry
, 1);
1404 setter
= XEXP (list_entry
, 0);
1406 /* If SETTER is a call everything is clobbered. Note that calls
1407 to pure functions are never put on the list, so we need not
1408 worry about them. */
1409 if (CALL_P (setter
))
1412 /* SETTER must be an INSN of some kind that sets memory. Call
1413 note_stores to examine each hunk of memory that is modified.
1415 The note_stores interface is pretty limited, so we have to
1416 communicate via global variables. Yuk. */
1417 gcse_mem_operand
= x
;
1418 gcse_mems_conflict_p
= 0;
1419 note_stores (PATTERN (setter
), mems_conflict_for_gcse_p
, NULL
);
1420 if (gcse_mems_conflict_p
)
1422 list_entry
= XEXP (list_entry
, 1);
1427 /* Return nonzero if the operands of expression X are unchanged from
1428 the start of INSN's basic block up to but not including INSN. */
1431 oprs_anticipatable_p (rtx x
, rtx insn
)
1433 return oprs_unchanged_p (x
, insn
, 0);
1436 /* Return nonzero if the operands of expression X are unchanged from
1437 INSN to the end of INSN's basic block. */
1440 oprs_available_p (rtx x
, rtx insn
)
1442 return oprs_unchanged_p (x
, insn
, 1);
1445 /* Hash expression X.
1447 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1448 indicating if a volatile operand is found or if the expression contains
1449 something we don't want to insert in the table. HASH_TABLE_SIZE is
1450 the current size of the hash table to be probed. */
1453 hash_expr (rtx x
, enum machine_mode mode
, int *do_not_record_p
,
1454 int hash_table_size
)
1458 *do_not_record_p
= 0;
1460 hash
= hash_rtx (x
, mode
, do_not_record_p
,
1461 NULL
, /*have_reg_qty=*/false);
1462 return hash
% hash_table_size
;
1465 /* Hash a set of register REGNO.
1467 Sets are hashed on the register that is set. This simplifies the PRE copy
1470 ??? May need to make things more elaborate. Later, as necessary. */
1473 hash_set (int regno
, int hash_table_size
)
1478 return hash
% hash_table_size
;
1481 /* Return nonzero if exp1 is equivalent to exp2. */
1484 expr_equiv_p (rtx x
, rtx y
)
1486 return exp_equiv_p (x
, y
, 0, true);
1489 /* Insert expression X in INSN in the hash TABLE.
1490 If it is already present, record it as the last occurrence in INSN's
1493 MODE is the mode of the value X is being stored into.
1494 It is only used if X is a CONST_INT.
1496 ANTIC_P is nonzero if X is an anticipatable expression.
1497 AVAIL_P is nonzero if X is an available expression. */
1500 insert_expr_in_table (rtx x
, enum machine_mode mode
, rtx insn
, int antic_p
,
1501 int avail_p
, struct hash_table
*table
)
1503 int found
, do_not_record_p
;
1505 struct expr
*cur_expr
, *last_expr
= NULL
;
1506 struct occr
*antic_occr
, *avail_occr
;
1508 hash
= hash_expr (x
, mode
, &do_not_record_p
, table
->size
);
1510 /* Do not insert expression in table if it contains volatile operands,
1511 or if hash_expr determines the expression is something we don't want
1512 to or can't handle. */
1513 if (do_not_record_p
)
1516 cur_expr
= table
->table
[hash
];
1519 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1521 /* If the expression isn't found, save a pointer to the end of
1523 last_expr
= cur_expr
;
1524 cur_expr
= cur_expr
->next_same_hash
;
1529 cur_expr
= gcse_alloc (sizeof (struct expr
));
1530 bytes_used
+= sizeof (struct expr
);
1531 if (table
->table
[hash
] == NULL
)
1532 /* This is the first pattern that hashed to this index. */
1533 table
->table
[hash
] = cur_expr
;
1535 /* Add EXPR to end of this hash chain. */
1536 last_expr
->next_same_hash
= cur_expr
;
1538 /* Set the fields of the expr element. */
1540 cur_expr
->bitmap_index
= table
->n_elems
++;
1541 cur_expr
->next_same_hash
= NULL
;
1542 cur_expr
->antic_occr
= NULL
;
1543 cur_expr
->avail_occr
= NULL
;
1546 /* Now record the occurrence(s). */
1549 antic_occr
= cur_expr
->antic_occr
;
1551 if (antic_occr
&& BLOCK_NUM (antic_occr
->insn
) != BLOCK_NUM (insn
))
1555 /* Found another instance of the expression in the same basic block.
1556 Prefer the currently recorded one. We want the first one in the
1557 block and the block is scanned from start to end. */
1558 ; /* nothing to do */
1561 /* First occurrence of this expression in this basic block. */
1562 antic_occr
= gcse_alloc (sizeof (struct occr
));
1563 bytes_used
+= sizeof (struct occr
);
1564 antic_occr
->insn
= insn
;
1565 antic_occr
->next
= cur_expr
->antic_occr
;
1566 antic_occr
->deleted_p
= 0;
1567 cur_expr
->antic_occr
= antic_occr
;
1573 avail_occr
= cur_expr
->avail_occr
;
1575 if (avail_occr
&& BLOCK_NUM (avail_occr
->insn
) == BLOCK_NUM (insn
))
1577 /* Found another instance of the expression in the same basic block.
1578 Prefer this occurrence to the currently recorded one. We want
1579 the last one in the block and the block is scanned from start
1581 avail_occr
->insn
= insn
;
1585 /* First occurrence of this expression in this basic block. */
1586 avail_occr
= gcse_alloc (sizeof (struct occr
));
1587 bytes_used
+= sizeof (struct occr
);
1588 avail_occr
->insn
= insn
;
1589 avail_occr
->next
= cur_expr
->avail_occr
;
1590 avail_occr
->deleted_p
= 0;
1591 cur_expr
->avail_occr
= avail_occr
;
1596 /* Insert pattern X in INSN in the hash table.
1597 X is a SET of a reg to either another reg or a constant.
1598 If it is already present, record it as the last occurrence in INSN's
1602 insert_set_in_table (rtx x
, rtx insn
, struct hash_table
*table
)
1606 struct expr
*cur_expr
, *last_expr
= NULL
;
1607 struct occr
*cur_occr
;
1609 gcc_assert (GET_CODE (x
) == SET
&& REG_P (SET_DEST (x
)));
1611 hash
= hash_set (REGNO (SET_DEST (x
)), table
->size
);
1613 cur_expr
= table
->table
[hash
];
1616 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1618 /* If the expression isn't found, save a pointer to the end of
1620 last_expr
= cur_expr
;
1621 cur_expr
= cur_expr
->next_same_hash
;
1626 cur_expr
= gcse_alloc (sizeof (struct expr
));
1627 bytes_used
+= sizeof (struct expr
);
1628 if (table
->table
[hash
] == NULL
)
1629 /* This is the first pattern that hashed to this index. */
1630 table
->table
[hash
] = cur_expr
;
1632 /* Add EXPR to end of this hash chain. */
1633 last_expr
->next_same_hash
= cur_expr
;
1635 /* Set the fields of the expr element.
1636 We must copy X because it can be modified when copy propagation is
1637 performed on its operands. */
1638 cur_expr
->expr
= copy_rtx (x
);
1639 cur_expr
->bitmap_index
= table
->n_elems
++;
1640 cur_expr
->next_same_hash
= NULL
;
1641 cur_expr
->antic_occr
= NULL
;
1642 cur_expr
->avail_occr
= NULL
;
1645 /* Now record the occurrence. */
1646 cur_occr
= cur_expr
->avail_occr
;
1648 if (cur_occr
&& BLOCK_NUM (cur_occr
->insn
) == BLOCK_NUM (insn
))
1650 /* Found another instance of the expression in the same basic block.
1651 Prefer this occurrence to the currently recorded one. We want
1652 the last one in the block and the block is scanned from start
1654 cur_occr
->insn
= insn
;
1658 /* First occurrence of this expression in this basic block. */
1659 cur_occr
= gcse_alloc (sizeof (struct occr
));
1660 bytes_used
+= sizeof (struct occr
);
1662 cur_occr
->insn
= insn
;
1663 cur_occr
->next
= cur_expr
->avail_occr
;
1664 cur_occr
->deleted_p
= 0;
1665 cur_expr
->avail_occr
= cur_occr
;
1669 /* Determine whether the rtx X should be treated as a constant for
1670 the purposes of GCSE's constant propagation. */
1673 gcse_constant_p (rtx x
)
1675 /* Consider a COMPARE of two integers constant. */
1676 if (GET_CODE (x
) == COMPARE
1677 && GET_CODE (XEXP (x
, 0)) == CONST_INT
1678 && GET_CODE (XEXP (x
, 1)) == CONST_INT
)
1681 /* Consider a COMPARE of the same registers is a constant
1682 if they are not floating point registers. */
1683 if (GET_CODE(x
) == COMPARE
1684 && REG_P (XEXP (x
, 0)) && REG_P (XEXP (x
, 1))
1685 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (x
, 1))
1686 && ! FLOAT_MODE_P (GET_MODE (XEXP (x
, 0)))
1687 && ! FLOAT_MODE_P (GET_MODE (XEXP (x
, 1))))
1690 return CONSTANT_P (x
);
1693 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
1697 hash_scan_set (rtx pat
, rtx insn
, struct hash_table
*table
)
1699 rtx src
= SET_SRC (pat
);
1700 rtx dest
= SET_DEST (pat
);
1703 if (GET_CODE (src
) == CALL
)
1704 hash_scan_call (src
, insn
, table
);
1706 else if (REG_P (dest
))
1708 unsigned int regno
= REGNO (dest
);
1711 /* If this is a single set and we are doing constant propagation,
1712 see if a REG_NOTE shows this equivalent to a constant. */
1713 if (table
->set_p
&& (note
= find_reg_equal_equiv_note (insn
)) != 0
1714 && gcse_constant_p (XEXP (note
, 0)))
1715 src
= XEXP (note
, 0), pat
= gen_rtx_SET (VOIDmode
, dest
, src
);
1717 /* Only record sets of pseudo-regs in the hash table. */
1719 && regno
>= FIRST_PSEUDO_REGISTER
1720 /* Don't GCSE something if we can't do a reg/reg copy. */
1721 && can_copy_p (GET_MODE (dest
))
1722 /* GCSE commonly inserts instruction after the insn. We can't
1723 do that easily for EH_REGION notes so disable GCSE on these
1725 && !find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
1726 /* Is SET_SRC something we want to gcse? */
1727 && want_to_gcse_p (src
)
1728 /* Don't CSE a nop. */
1729 && ! set_noop_p (pat
)
1730 /* Don't GCSE if it has attached REG_EQUIV note.
1731 At this point this only function parameters should have
1732 REG_EQUIV notes and if the argument slot is used somewhere
1733 explicitly, it means address of parameter has been taken,
1734 so we should not extend the lifetime of the pseudo. */
1735 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
1736 || ! MEM_P (XEXP (note
, 0))))
1738 /* An expression is not anticipatable if its operands are
1739 modified before this insn or if this is not the only SET in
1741 int antic_p
= oprs_anticipatable_p (src
, insn
) && single_set (insn
);
1742 /* An expression is not available if its operands are
1743 subsequently modified, including this insn. It's also not
1744 available if this is a branch, because we can't insert
1745 a set after the branch. */
1746 int avail_p
= (oprs_available_p (src
, insn
)
1747 && ! JUMP_P (insn
));
1749 insert_expr_in_table (src
, GET_MODE (dest
), insn
, antic_p
, avail_p
, table
);
1752 /* Record sets for constant/copy propagation. */
1753 else if (table
->set_p
1754 && regno
>= FIRST_PSEUDO_REGISTER
1756 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
1757 && can_copy_p (GET_MODE (dest
))
1758 && REGNO (src
) != regno
)
1759 || gcse_constant_p (src
))
1760 /* A copy is not available if its src or dest is subsequently
1761 modified. Here we want to search from INSN+1 on, but
1762 oprs_available_p searches from INSN on. */
1763 && (insn
== BB_END (BLOCK_FOR_INSN (insn
))
1764 || ((tmp
= next_nonnote_insn (insn
)) != NULL_RTX
1765 && oprs_available_p (pat
, tmp
))))
1766 insert_set_in_table (pat
, insn
, table
);
1768 /* In case of store we want to consider the memory value as available in
1769 the REG stored in that memory. This makes it possible to remove
1770 redundant loads from due to stores to the same location. */
1771 else if (flag_gcse_las
&& REG_P (src
) && MEM_P (dest
))
1773 unsigned int regno
= REGNO (src
);
1775 /* Do not do this for constant/copy propagation. */
1777 /* Only record sets of pseudo-regs in the hash table. */
1778 && regno
>= FIRST_PSEUDO_REGISTER
1779 /* Don't GCSE something if we can't do a reg/reg copy. */
1780 && can_copy_p (GET_MODE (src
))
1781 /* GCSE commonly inserts instruction after the insn. We can't
1782 do that easily for EH_REGION notes so disable GCSE on these
1784 && ! find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
1785 /* Is SET_DEST something we want to gcse? */
1786 && want_to_gcse_p (dest
)
1787 /* Don't CSE a nop. */
1788 && ! set_noop_p (pat
)
1789 /* Don't GCSE if it has attached REG_EQUIV note.
1790 At this point this only function parameters should have
1791 REG_EQUIV notes and if the argument slot is used somewhere
1792 explicitly, it means address of parameter has been taken,
1793 so we should not extend the lifetime of the pseudo. */
1794 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
1795 || ! MEM_P (XEXP (note
, 0))))
1797 /* Stores are never anticipatable. */
1799 /* An expression is not available if its operands are
1800 subsequently modified, including this insn. It's also not
1801 available if this is a branch, because we can't insert
1802 a set after the branch. */
1803 int avail_p
= oprs_available_p (dest
, insn
)
1806 /* Record the memory expression (DEST) in the hash table. */
1807 insert_expr_in_table (dest
, GET_MODE (dest
), insn
,
1808 antic_p
, avail_p
, table
);
1814 hash_scan_clobber (rtx x ATTRIBUTE_UNUSED
, rtx insn ATTRIBUTE_UNUSED
,
1815 struct hash_table
*table ATTRIBUTE_UNUSED
)
1817 /* Currently nothing to do. */
1821 hash_scan_call (rtx x ATTRIBUTE_UNUSED
, rtx insn ATTRIBUTE_UNUSED
,
1822 struct hash_table
*table ATTRIBUTE_UNUSED
)
1824 /* Currently nothing to do. */
1827 /* Process INSN and add hash table entries as appropriate.
1829 Only available expressions that set a single pseudo-reg are recorded.
1831 Single sets in a PARALLEL could be handled, but it's an extra complication
1832 that isn't dealt with right now. The trick is handling the CLOBBERs that
1833 are also in the PARALLEL. Later.
1835 If SET_P is nonzero, this is for the assignment hash table,
1836 otherwise it is for the expression hash table.
1837 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
1838 not record any expressions. */
1841 hash_scan_insn (rtx insn
, struct hash_table
*table
, int in_libcall_block
)
1843 rtx pat
= PATTERN (insn
);
1846 if (in_libcall_block
)
1849 /* Pick out the sets of INSN and for other forms of instructions record
1850 what's been modified. */
1852 if (GET_CODE (pat
) == SET
)
1853 hash_scan_set (pat
, insn
, table
);
1854 else if (GET_CODE (pat
) == PARALLEL
)
1855 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
1857 rtx x
= XVECEXP (pat
, 0, i
);
1859 if (GET_CODE (x
) == SET
)
1860 hash_scan_set (x
, insn
, table
);
1861 else if (GET_CODE (x
) == CLOBBER
)
1862 hash_scan_clobber (x
, insn
, table
);
1863 else if (GET_CODE (x
) == CALL
)
1864 hash_scan_call (x
, insn
, table
);
1867 else if (GET_CODE (pat
) == CLOBBER
)
1868 hash_scan_clobber (pat
, insn
, table
);
1869 else if (GET_CODE (pat
) == CALL
)
1870 hash_scan_call (pat
, insn
, table
);
1874 dump_hash_table (FILE *file
, const char *name
, struct hash_table
*table
)
1877 /* Flattened out table, so it's printed in proper order. */
1878 struct expr
**flat_table
;
1879 unsigned int *hash_val
;
1882 flat_table
= xcalloc (table
->n_elems
, sizeof (struct expr
*));
1883 hash_val
= xmalloc (table
->n_elems
* sizeof (unsigned int));
1885 for (i
= 0; i
< (int) table
->size
; i
++)
1886 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1888 flat_table
[expr
->bitmap_index
] = expr
;
1889 hash_val
[expr
->bitmap_index
] = i
;
1892 fprintf (file
, "%s hash table (%d buckets, %d entries)\n",
1893 name
, table
->size
, table
->n_elems
);
1895 for (i
= 0; i
< (int) table
->n_elems
; i
++)
1896 if (flat_table
[i
] != 0)
1898 expr
= flat_table
[i
];
1899 fprintf (file
, "Index %d (hash value %d)\n ",
1900 expr
->bitmap_index
, hash_val
[i
]);
1901 print_rtl (file
, expr
->expr
);
1902 fprintf (file
, "\n");
1905 fprintf (file
, "\n");
1911 /* Record register first/last/block set information for REGNO in INSN.
1913 first_set records the first place in the block where the register
1914 is set and is used to compute "anticipatability".
1916 last_set records the last place in the block where the register
1917 is set and is used to compute "availability".
1919 last_bb records the block for which first_set and last_set are
1920 valid, as a quick test to invalidate them.
1922 reg_set_in_block records whether the register is set in the block
1923 and is used to compute "transparency". */
1926 record_last_reg_set_info (rtx insn
, int regno
)
1928 struct reg_avail_info
*info
= ®_avail_info
[regno
];
1929 int cuid
= INSN_CUID (insn
);
1931 info
->last_set
= cuid
;
1932 if (info
->last_bb
!= current_bb
)
1934 info
->last_bb
= current_bb
;
1935 info
->first_set
= cuid
;
1936 SET_BIT (reg_set_in_block
[current_bb
->index
], regno
);
1941 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
1942 Note we store a pair of elements in the list, so they have to be
1943 taken off pairwise. */
1946 canon_list_insert (rtx dest ATTRIBUTE_UNUSED
, rtx unused1 ATTRIBUTE_UNUSED
,
1949 rtx dest_addr
, insn
;
1952 while (GET_CODE (dest
) == SUBREG
1953 || GET_CODE (dest
) == ZERO_EXTRACT
1954 || GET_CODE (dest
) == STRICT_LOW_PART
)
1955 dest
= XEXP (dest
, 0);
1957 /* If DEST is not a MEM, then it will not conflict with a load. Note
1958 that function calls are assumed to clobber memory, but are handled
1964 dest_addr
= get_addr (XEXP (dest
, 0));
1965 dest_addr
= canon_rtx (dest_addr
);
1966 insn
= (rtx
) v_insn
;
1967 bb
= BLOCK_NUM (insn
);
1969 canon_modify_mem_list
[bb
] =
1970 alloc_EXPR_LIST (VOIDmode
, dest_addr
, canon_modify_mem_list
[bb
]);
1971 canon_modify_mem_list
[bb
] =
1972 alloc_EXPR_LIST (VOIDmode
, dest
, canon_modify_mem_list
[bb
]);
1973 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
1976 /* Record memory modification information for INSN. We do not actually care
1977 about the memory location(s) that are set, or even how they are set (consider
1978 a CALL_INSN). We merely need to record which insns modify memory. */
1981 record_last_mem_set_info (rtx insn
)
1983 int bb
= BLOCK_NUM (insn
);
1985 /* load_killed_in_block_p will handle the case of calls clobbering
1987 modify_mem_list
[bb
] = alloc_INSN_LIST (insn
, modify_mem_list
[bb
]);
1988 bitmap_set_bit (modify_mem_list_set
, bb
);
1992 /* Note that traversals of this loop (other than for free-ing)
1993 will break after encountering a CALL_INSN. So, there's no
1994 need to insert a pair of items, as canon_list_insert does. */
1995 canon_modify_mem_list
[bb
] =
1996 alloc_INSN_LIST (insn
, canon_modify_mem_list
[bb
]);
1997 bitmap_set_bit (canon_modify_mem_list_set
, bb
);
2000 note_stores (PATTERN (insn
), canon_list_insert
, (void*) insn
);
2003 /* Called from compute_hash_table via note_stores to handle one
2004 SET or CLOBBER in an insn. DATA is really the instruction in which
2005 the SET is taking place. */
2008 record_last_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
, void *data
)
2010 rtx last_set_insn
= (rtx
) data
;
2012 if (GET_CODE (dest
) == SUBREG
)
2013 dest
= SUBREG_REG (dest
);
2016 record_last_reg_set_info (last_set_insn
, REGNO (dest
));
2017 else if (MEM_P (dest
)
2018 /* Ignore pushes, they clobber nothing. */
2019 && ! push_operand (dest
, GET_MODE (dest
)))
2020 record_last_mem_set_info (last_set_insn
);
2023 /* Top level function to create an expression or assignment hash table.
2025 Expression entries are placed in the hash table if
2026 - they are of the form (set (pseudo-reg) src),
2027 - src is something we want to perform GCSE on,
2028 - none of the operands are subsequently modified in the block
2030 Assignment entries are placed in the hash table if
2031 - they are of the form (set (pseudo-reg) src),
2032 - src is something we want to perform const/copy propagation on,
2033 - none of the operands or target are subsequently modified in the block
2035 Currently src must be a pseudo-reg or a const_int.
2037 TABLE is the table computed. */
2040 compute_hash_table_work (struct hash_table
*table
)
2044 /* While we compute the hash table we also compute a bit array of which
2045 registers are set in which blocks.
2046 ??? This isn't needed during const/copy propagation, but it's cheap to
2048 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
2050 /* re-Cache any INSN_LIST nodes we have allocated. */
2051 clear_modify_mem_tables ();
2052 /* Some working arrays used to track first and last set in each block. */
2053 reg_avail_info
= gmalloc (max_gcse_regno
* sizeof (struct reg_avail_info
));
2055 for (i
= 0; i
< max_gcse_regno
; ++i
)
2056 reg_avail_info
[i
].last_bb
= NULL
;
2058 FOR_EACH_BB (current_bb
)
2062 int in_libcall_block
;
2064 /* First pass over the instructions records information used to
2065 determine when registers and memory are first and last set.
2066 ??? hard-reg reg_set_in_block computation
2067 could be moved to compute_sets since they currently don't change. */
2069 for (insn
= BB_HEAD (current_bb
);
2070 insn
&& insn
!= NEXT_INSN (BB_END (current_bb
));
2071 insn
= NEXT_INSN (insn
))
2073 if (! INSN_P (insn
))
2078 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2079 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2080 record_last_reg_set_info (insn
, regno
);
2085 note_stores (PATTERN (insn
), record_last_set_info
, insn
);
2088 /* Insert implicit sets in the hash table. */
2090 && implicit_sets
[current_bb
->index
] != NULL_RTX
)
2091 hash_scan_set (implicit_sets
[current_bb
->index
],
2092 BB_HEAD (current_bb
), table
);
2094 /* The next pass builds the hash table. */
2096 for (insn
= BB_HEAD (current_bb
), in_libcall_block
= 0;
2097 insn
&& insn
!= NEXT_INSN (BB_END (current_bb
));
2098 insn
= NEXT_INSN (insn
))
2101 if (find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2102 in_libcall_block
= 1;
2103 else if (table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2104 in_libcall_block
= 0;
2105 hash_scan_insn (insn
, table
, in_libcall_block
);
2106 if (!table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2107 in_libcall_block
= 0;
2111 free (reg_avail_info
);
2112 reg_avail_info
= NULL
;
2115 /* Allocate space for the set/expr hash TABLE.
2116 N_INSNS is the number of instructions in the function.
2117 It is used to determine the number of buckets to use.
2118 SET_P determines whether set or expression table will
2122 alloc_hash_table (int n_insns
, struct hash_table
*table
, int set_p
)
2126 table
->size
= n_insns
/ 4;
2127 if (table
->size
< 11)
2130 /* Attempt to maintain efficient use of hash table.
2131 Making it an odd number is simplest for now.
2132 ??? Later take some measurements. */
2134 n
= table
->size
* sizeof (struct expr
*);
2135 table
->table
= gmalloc (n
);
2136 table
->set_p
= set_p
;
2139 /* Free things allocated by alloc_hash_table. */
2142 free_hash_table (struct hash_table
*table
)
2144 free (table
->table
);
2147 /* Compute the hash TABLE for doing copy/const propagation or
2148 expression hash table. */
2151 compute_hash_table (struct hash_table
*table
)
2153 /* Initialize count of number of entries in hash table. */
2155 memset (table
->table
, 0, table
->size
* sizeof (struct expr
*));
2157 compute_hash_table_work (table
);
2160 /* Expression tracking support. */
2162 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2163 table entry, or NULL if not found. */
2165 static struct expr
*
2166 lookup_set (unsigned int regno
, struct hash_table
*table
)
2168 unsigned int hash
= hash_set (regno
, table
->size
);
2171 expr
= table
->table
[hash
];
2173 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
)
2174 expr
= expr
->next_same_hash
;
2179 /* Return the next entry for REGNO in list EXPR. */
2181 static struct expr
*
2182 next_set (unsigned int regno
, struct expr
*expr
)
2185 expr
= expr
->next_same_hash
;
2186 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
);
2191 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2192 types may be mixed. */
2195 free_insn_expr_list_list (rtx
*listp
)
2199 for (list
= *listp
; list
; list
= next
)
2201 next
= XEXP (list
, 1);
2202 if (GET_CODE (list
) == EXPR_LIST
)
2203 free_EXPR_LIST_node (list
);
2205 free_INSN_LIST_node (list
);
2211 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2213 clear_modify_mem_tables (void)
2218 EXECUTE_IF_SET_IN_BITMAP (modify_mem_list_set
, 0, i
, bi
)
2220 free_INSN_LIST_list (modify_mem_list
+ i
);
2222 bitmap_clear (modify_mem_list_set
);
2224 EXECUTE_IF_SET_IN_BITMAP (canon_modify_mem_list_set
, 0, i
, bi
)
2226 free_insn_expr_list_list (canon_modify_mem_list
+ i
);
2228 bitmap_clear (canon_modify_mem_list_set
);
2231 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2234 free_modify_mem_tables (void)
2236 clear_modify_mem_tables ();
2237 free (modify_mem_list
);
2238 free (canon_modify_mem_list
);
2239 modify_mem_list
= 0;
2240 canon_modify_mem_list
= 0;
2243 /* Reset tables used to keep track of what's still available [since the
2244 start of the block]. */
2247 reset_opr_set_tables (void)
2249 /* Maintain a bitmap of which regs have been set since beginning of
2251 CLEAR_REG_SET (reg_set_bitmap
);
2253 /* Also keep a record of the last instruction to modify memory.
2254 For now this is very trivial, we only record whether any memory
2255 location has been modified. */
2256 clear_modify_mem_tables ();
2259 /* Return nonzero if the operands of X are not set before INSN in
2260 INSN's basic block. */
2263 oprs_not_set_p (rtx x
, rtx insn
)
2272 code
= GET_CODE (x
);
2288 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn
),
2289 INSN_CUID (insn
), x
, 0))
2292 return oprs_not_set_p (XEXP (x
, 0), insn
);
2295 return ! REGNO_REG_SET_P (reg_set_bitmap
, REGNO (x
));
2301 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2305 /* If we are about to do the last recursive call
2306 needed at this level, change it into iteration.
2307 This function is called enough to be worth it. */
2309 return oprs_not_set_p (XEXP (x
, i
), insn
);
2311 if (! oprs_not_set_p (XEXP (x
, i
), insn
))
2314 else if (fmt
[i
] == 'E')
2315 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2316 if (! oprs_not_set_p (XVECEXP (x
, i
, j
), insn
))
2323 /* Mark things set by a CALL. */
2326 mark_call (rtx insn
)
2328 if (! CONST_OR_PURE_CALL_P (insn
))
2329 record_last_mem_set_info (insn
);
2332 /* Mark things set by a SET. */
2335 mark_set (rtx pat
, rtx insn
)
2337 rtx dest
= SET_DEST (pat
);
2339 while (GET_CODE (dest
) == SUBREG
2340 || GET_CODE (dest
) == ZERO_EXTRACT
2341 || GET_CODE (dest
) == STRICT_LOW_PART
)
2342 dest
= XEXP (dest
, 0);
2345 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (dest
));
2346 else if (MEM_P (dest
))
2347 record_last_mem_set_info (insn
);
2349 if (GET_CODE (SET_SRC (pat
)) == CALL
)
2353 /* Record things set by a CLOBBER. */
2356 mark_clobber (rtx pat
, rtx insn
)
2358 rtx clob
= XEXP (pat
, 0);
2360 while (GET_CODE (clob
) == SUBREG
|| GET_CODE (clob
) == STRICT_LOW_PART
)
2361 clob
= XEXP (clob
, 0);
2364 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (clob
));
2366 record_last_mem_set_info (insn
);
2369 /* Record things set by INSN.
2370 This data is used by oprs_not_set_p. */
2373 mark_oprs_set (rtx insn
)
2375 rtx pat
= PATTERN (insn
);
2378 if (GET_CODE (pat
) == SET
)
2379 mark_set (pat
, insn
);
2380 else if (GET_CODE (pat
) == PARALLEL
)
2381 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2383 rtx x
= XVECEXP (pat
, 0, i
);
2385 if (GET_CODE (x
) == SET
)
2387 else if (GET_CODE (x
) == CLOBBER
)
2388 mark_clobber (x
, insn
);
2389 else if (GET_CODE (x
) == CALL
)
2393 else if (GET_CODE (pat
) == CLOBBER
)
2394 mark_clobber (pat
, insn
);
2395 else if (GET_CODE (pat
) == CALL
)
2400 /* Compute copy/constant propagation working variables. */
2402 /* Local properties of assignments. */
2403 static sbitmap
*cprop_pavloc
;
2404 static sbitmap
*cprop_absaltered
;
2406 /* Global properties of assignments (computed from the local properties). */
2407 static sbitmap
*cprop_avin
;
2408 static sbitmap
*cprop_avout
;
2410 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
2411 basic blocks. N_SETS is the number of sets. */
2414 alloc_cprop_mem (int n_blocks
, int n_sets
)
2416 cprop_pavloc
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2417 cprop_absaltered
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2419 cprop_avin
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2420 cprop_avout
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2423 /* Free vars used by copy/const propagation. */
2426 free_cprop_mem (void)
2428 sbitmap_vector_free (cprop_pavloc
);
2429 sbitmap_vector_free (cprop_absaltered
);
2430 sbitmap_vector_free (cprop_avin
);
2431 sbitmap_vector_free (cprop_avout
);
2434 /* For each block, compute whether X is transparent. X is either an
2435 expression or an assignment [though we don't care which, for this context
2436 an assignment is treated as an expression]. For each block where an
2437 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
2441 compute_transp (rtx x
, int indx
, sbitmap
*bmap
, int set_p
)
2449 /* repeat is used to turn tail-recursion into iteration since GCC
2450 can't do it when there's no return value. */
2456 code
= GET_CODE (x
);
2462 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
2465 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
2466 SET_BIT (bmap
[bb
->index
], indx
);
2470 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
2471 SET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
2476 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
2479 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
2480 RESET_BIT (bmap
[bb
->index
], indx
);
2484 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
2485 RESET_BIT (bmap
[BLOCK_NUM (r
->insn
)], indx
);
2494 rtx list_entry
= canon_modify_mem_list
[bb
->index
];
2498 rtx dest
, dest_addr
;
2500 if (CALL_P (XEXP (list_entry
, 0)))
2503 SET_BIT (bmap
[bb
->index
], indx
);
2505 RESET_BIT (bmap
[bb
->index
], indx
);
2508 /* LIST_ENTRY must be an INSN of some kind that sets memory.
2509 Examine each hunk of memory that is modified. */
2511 dest
= XEXP (list_entry
, 0);
2512 list_entry
= XEXP (list_entry
, 1);
2513 dest_addr
= XEXP (list_entry
, 0);
2515 if (canon_true_dependence (dest
, GET_MODE (dest
), dest_addr
,
2516 x
, rtx_addr_varies_p
))
2519 SET_BIT (bmap
[bb
->index
], indx
);
2521 RESET_BIT (bmap
[bb
->index
], indx
);
2524 list_entry
= XEXP (list_entry
, 1);
2547 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2551 /* If we are about to do the last recursive call
2552 needed at this level, change it into iteration.
2553 This function is called enough to be worth it. */
2560 compute_transp (XEXP (x
, i
), indx
, bmap
, set_p
);
2562 else if (fmt
[i
] == 'E')
2563 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2564 compute_transp (XVECEXP (x
, i
, j
), indx
, bmap
, set_p
);
2568 /* Top level routine to do the dataflow analysis needed by copy/const
2572 compute_cprop_data (void)
2574 compute_local_properties (cprop_absaltered
, cprop_pavloc
, NULL
, &set_hash_table
);
2575 compute_available (cprop_pavloc
, cprop_absaltered
,
2576 cprop_avout
, cprop_avin
);
2579 /* Copy/constant propagation. */
2581 /* Maximum number of register uses in an insn that we handle. */
2584 /* Table of uses found in an insn.
2585 Allocated statically to avoid alloc/free complexity and overhead. */
2586 static struct reg_use reg_use_table
[MAX_USES
];
2588 /* Index into `reg_use_table' while building it. */
2589 static int reg_use_count
;
2591 /* Set up a list of register numbers used in INSN. The found uses are stored
2592 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
2593 and contains the number of uses in the table upon exit.
2595 ??? If a register appears multiple times we will record it multiple times.
2596 This doesn't hurt anything but it will slow things down. */
2599 find_used_regs (rtx
*xptr
, void *data ATTRIBUTE_UNUSED
)
2606 /* repeat is used to turn tail-recursion into iteration since GCC
2607 can't do it when there's no return value. */
2612 code
= GET_CODE (x
);
2615 if (reg_use_count
== MAX_USES
)
2618 reg_use_table
[reg_use_count
].reg_rtx
= x
;
2622 /* Recursively scan the operands of this expression. */
2624 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2628 /* If we are about to do the last recursive call
2629 needed at this level, change it into iteration.
2630 This function is called enough to be worth it. */
2637 find_used_regs (&XEXP (x
, i
), data
);
2639 else if (fmt
[i
] == 'E')
2640 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2641 find_used_regs (&XVECEXP (x
, i
, j
), data
);
2645 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
2646 Returns nonzero is successful. */
2649 try_replace_reg (rtx from
, rtx to
, rtx insn
)
2651 rtx note
= find_reg_equal_equiv_note (insn
);
2654 rtx set
= single_set (insn
);
2656 validate_replace_src_group (from
, to
, insn
);
2657 if (num_changes_pending () && apply_change_group ())
2660 /* Try to simplify SET_SRC if we have substituted a constant. */
2661 if (success
&& set
&& CONSTANT_P (to
))
2663 src
= simplify_rtx (SET_SRC (set
));
2666 validate_change (insn
, &SET_SRC (set
), src
, 0);
2669 /* If there is already a NOTE, update the expression in it with our
2672 XEXP (note
, 0) = simplify_replace_rtx (XEXP (note
, 0), from
, to
);
2674 if (!success
&& set
&& reg_mentioned_p (from
, SET_SRC (set
)))
2676 /* If above failed and this is a single set, try to simplify the source of
2677 the set given our substitution. We could perhaps try this for multiple
2678 SETs, but it probably won't buy us anything. */
2679 src
= simplify_replace_rtx (SET_SRC (set
), from
, to
);
2681 if (!rtx_equal_p (src
, SET_SRC (set
))
2682 && validate_change (insn
, &SET_SRC (set
), src
, 0))
2685 /* If we've failed to do replacement, have a single SET, don't already
2686 have a note, and have no special SET, add a REG_EQUAL note to not
2687 lose information. */
2688 if (!success
&& note
== 0 && set
!= 0
2689 && GET_CODE (SET_DEST (set
)) != ZERO_EXTRACT
)
2690 note
= set_unique_reg_note (insn
, REG_EQUAL
, copy_rtx (src
));
2693 /* REG_EQUAL may get simplified into register.
2694 We don't allow that. Remove that note. This code ought
2695 not to happen, because previous code ought to synthesize
2696 reg-reg move, but be on the safe side. */
2697 if (note
&& REG_P (XEXP (note
, 0)))
2698 remove_note (insn
, note
);
2703 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
2704 NULL no such set is found. */
2706 static struct expr
*
2707 find_avail_set (int regno
, rtx insn
)
2709 /* SET1 contains the last set found that can be returned to the caller for
2710 use in a substitution. */
2711 struct expr
*set1
= 0;
2713 /* Loops are not possible here. To get a loop we would need two sets
2714 available at the start of the block containing INSN. i.e. we would
2715 need two sets like this available at the start of the block:
2717 (set (reg X) (reg Y))
2718 (set (reg Y) (reg X))
2720 This can not happen since the set of (reg Y) would have killed the
2721 set of (reg X) making it unavailable at the start of this block. */
2725 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
2727 /* Find a set that is available at the start of the block
2728 which contains INSN. */
2731 if (TEST_BIT (cprop_avin
[BLOCK_NUM (insn
)], set
->bitmap_index
))
2733 set
= next_set (regno
, set
);
2736 /* If no available set was found we've reached the end of the
2737 (possibly empty) copy chain. */
2741 gcc_assert (GET_CODE (set
->expr
) == SET
);
2743 src
= SET_SRC (set
->expr
);
2745 /* We know the set is available.
2746 Now check that SRC is ANTLOC (i.e. none of the source operands
2747 have changed since the start of the block).
2749 If the source operand changed, we may still use it for the next
2750 iteration of this loop, but we may not use it for substitutions. */
2752 if (gcse_constant_p (src
) || oprs_not_set_p (src
, insn
))
2755 /* If the source of the set is anything except a register, then
2756 we have reached the end of the copy chain. */
2760 /* Follow the copy chain, i.e. start another iteration of the loop
2761 and see if we have an available copy into SRC. */
2762 regno
= REGNO (src
);
2765 /* SET1 holds the last set that was available and anticipatable at
2770 /* Subroutine of cprop_insn that tries to propagate constants into
2771 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
2772 it is the instruction that immediately precedes JUMP, and must be a
2773 single SET of a register. FROM is what we will try to replace,
2774 SRC is the constant we will try to substitute for it. Returns nonzero
2775 if a change was made. */
2778 cprop_jump (basic_block bb
, rtx setcc
, rtx jump
, rtx from
, rtx src
)
2780 rtx
new, set_src
, note_src
;
2781 rtx set
= pc_set (jump
);
2782 rtx note
= find_reg_equal_equiv_note (jump
);
2786 note_src
= XEXP (note
, 0);
2787 if (GET_CODE (note_src
) == EXPR_LIST
)
2788 note_src
= NULL_RTX
;
2790 else note_src
= NULL_RTX
;
2792 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
2793 set_src
= note_src
? note_src
: SET_SRC (set
);
2795 /* First substitute the SETCC condition into the JUMP instruction,
2796 then substitute that given values into this expanded JUMP. */
2797 if (setcc
!= NULL_RTX
2798 && !modified_between_p (from
, setcc
, jump
)
2799 && !modified_between_p (src
, setcc
, jump
))
2802 rtx setcc_set
= single_set (setcc
);
2803 rtx setcc_note
= find_reg_equal_equiv_note (setcc
);
2804 setcc_src
= (setcc_note
&& GET_CODE (XEXP (setcc_note
, 0)) != EXPR_LIST
)
2805 ? XEXP (setcc_note
, 0) : SET_SRC (setcc_set
);
2806 set_src
= simplify_replace_rtx (set_src
, SET_DEST (setcc_set
),
2812 new = simplify_replace_rtx (set_src
, from
, src
);
2814 /* If no simplification can be made, then try the next register. */
2815 if (rtx_equal_p (new, SET_SRC (set
)))
2818 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
2823 /* Ensure the value computed inside the jump insn to be equivalent
2824 to one computed by setcc. */
2825 if (setcc
&& modified_in_p (new, setcc
))
2827 if (! validate_change (jump
, &SET_SRC (set
), new, 0))
2829 /* When (some) constants are not valid in a comparison, and there
2830 are two registers to be replaced by constants before the entire
2831 comparison can be folded into a constant, we need to keep
2832 intermediate information in REG_EQUAL notes. For targets with
2833 separate compare insns, such notes are added by try_replace_reg.
2834 When we have a combined compare-and-branch instruction, however,
2835 we need to attach a note to the branch itself to make this
2836 optimization work. */
2838 if (!rtx_equal_p (new, note_src
))
2839 set_unique_reg_note (jump
, REG_EQUAL
, copy_rtx (new));
2843 /* Remove REG_EQUAL note after simplification. */
2845 remove_note (jump
, note
);
2847 /* If this has turned into an unconditional jump,
2848 then put a barrier after it so that the unreachable
2849 code will be deleted. */
2850 if (GET_CODE (SET_SRC (set
)) == LABEL_REF
)
2851 emit_barrier_after (jump
);
2855 /* Delete the cc0 setter. */
2856 if (setcc
!= NULL
&& CC0_P (SET_DEST (single_set (setcc
))))
2857 delete_insn (setcc
);
2860 run_jump_opt_after_gcse
= 1;
2862 global_const_prop_count
++;
2863 if (gcse_file
!= NULL
)
2866 "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
2867 REGNO (from
), INSN_UID (jump
));
2868 print_rtl (gcse_file
, src
);
2869 fprintf (gcse_file
, "\n");
2871 purge_dead_edges (bb
);
2877 constprop_register (rtx insn
, rtx from
, rtx to
, int alter_jumps
)
2881 /* Check for reg or cc0 setting instructions followed by
2882 conditional branch instructions first. */
2884 && (sset
= single_set (insn
)) != NULL
2886 && any_condjump_p (NEXT_INSN (insn
)) && onlyjump_p (NEXT_INSN (insn
)))
2888 rtx dest
= SET_DEST (sset
);
2889 if ((REG_P (dest
) || CC0_P (dest
))
2890 && cprop_jump (BLOCK_FOR_INSN (insn
), insn
, NEXT_INSN (insn
), from
, to
))
2894 /* Handle normal insns next. */
2895 if (NONJUMP_INSN_P (insn
)
2896 && try_replace_reg (from
, to
, insn
))
2899 /* Try to propagate a CONST_INT into a conditional jump.
2900 We're pretty specific about what we will handle in this
2901 code, we can extend this as necessary over time.
2903 Right now the insn in question must look like
2904 (set (pc) (if_then_else ...)) */
2905 else if (alter_jumps
&& any_condjump_p (insn
) && onlyjump_p (insn
))
2906 return cprop_jump (BLOCK_FOR_INSN (insn
), NULL
, insn
, from
, to
);
2910 /* Perform constant and copy propagation on INSN.
2911 The result is nonzero if a change was made. */
2914 cprop_insn (rtx insn
, int alter_jumps
)
2916 struct reg_use
*reg_used
;
2924 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
2926 note
= find_reg_equal_equiv_note (insn
);
2928 /* We may win even when propagating constants into notes. */
2930 find_used_regs (&XEXP (note
, 0), NULL
);
2932 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
2933 reg_used
++, reg_use_count
--)
2935 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
2939 /* Ignore registers created by GCSE.
2940 We do this because ... */
2941 if (regno
>= max_gcse_regno
)
2944 /* If the register has already been set in this block, there's
2945 nothing we can do. */
2946 if (! oprs_not_set_p (reg_used
->reg_rtx
, insn
))
2949 /* Find an assignment that sets reg_used and is available
2950 at the start of the block. */
2951 set
= find_avail_set (regno
, insn
);
2956 /* ??? We might be able to handle PARALLELs. Later. */
2957 gcc_assert (GET_CODE (pat
) == SET
);
2959 src
= SET_SRC (pat
);
2961 /* Constant propagation. */
2962 if (gcse_constant_p (src
))
2964 if (constprop_register (insn
, reg_used
->reg_rtx
, src
, alter_jumps
))
2967 global_const_prop_count
++;
2968 if (gcse_file
!= NULL
)
2970 fprintf (gcse_file
, "GLOBAL CONST-PROP: Replacing reg %d in ", regno
);
2971 fprintf (gcse_file
, "insn %d with constant ", INSN_UID (insn
));
2972 print_rtl (gcse_file
, src
);
2973 fprintf (gcse_file
, "\n");
2975 if (INSN_DELETED_P (insn
))
2979 else if (REG_P (src
)
2980 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
2981 && REGNO (src
) != regno
)
2983 if (try_replace_reg (reg_used
->reg_rtx
, src
, insn
))
2986 global_copy_prop_count
++;
2987 if (gcse_file
!= NULL
)
2989 fprintf (gcse_file
, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
2990 regno
, INSN_UID (insn
));
2991 fprintf (gcse_file
, " with reg %d\n", REGNO (src
));
2994 /* The original insn setting reg_used may or may not now be
2995 deletable. We leave the deletion to flow. */
2996 /* FIXME: If it turns out that the insn isn't deletable,
2997 then we may have unnecessarily extended register lifetimes
2998 and made things worse. */
3006 /* Like find_used_regs, but avoid recording uses that appear in
3007 input-output contexts such as zero_extract or pre_dec. This
3008 restricts the cases we consider to those for which local cprop
3009 can legitimately make replacements. */
3012 local_cprop_find_used_regs (rtx
*xptr
, void *data
)
3019 switch (GET_CODE (x
))
3023 case STRICT_LOW_PART
:
3032 /* Can only legitimately appear this early in the context of
3033 stack pushes for function arguments, but handle all of the
3034 codes nonetheless. */
3038 /* Setting a subreg of a register larger than word_mode leaves
3039 the non-written words unchanged. */
3040 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x
))) > BITS_PER_WORD
)
3048 find_used_regs (xptr
, data
);
3051 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3052 their REG_EQUAL notes need updating. */
3055 do_local_cprop (rtx x
, rtx insn
, int alter_jumps
, rtx
*libcall_sp
)
3057 rtx newreg
= NULL
, newcnst
= NULL
;
3059 /* Rule out USE instructions and ASM statements as we don't want to
3060 change the hard registers mentioned. */
3062 && (REGNO (x
) >= FIRST_PSEUDO_REGISTER
3063 || (GET_CODE (PATTERN (insn
)) != USE
3064 && asm_noperands (PATTERN (insn
)) < 0)))
3066 cselib_val
*val
= cselib_lookup (x
, GET_MODE (x
), 0);
3067 struct elt_loc_list
*l
;
3071 for (l
= val
->locs
; l
; l
= l
->next
)
3073 rtx this_rtx
= l
->loc
;
3076 /* Don't CSE non-constant values out of libcall blocks. */
3077 if (l
->in_libcall
&& ! CONSTANT_P (this_rtx
))
3080 if (gcse_constant_p (this_rtx
))
3082 if (REG_P (this_rtx
) && REGNO (this_rtx
) >= FIRST_PSEUDO_REGISTER
3083 /* Don't copy propagate if it has attached REG_EQUIV note.
3084 At this point this only function parameters should have
3085 REG_EQUIV notes and if the argument slot is used somewhere
3086 explicitly, it means address of parameter has been taken,
3087 so we should not extend the lifetime of the pseudo. */
3088 && (!(note
= find_reg_note (l
->setting_insn
, REG_EQUIV
, NULL_RTX
))
3089 || ! MEM_P (XEXP (note
, 0))))
3092 if (newcnst
&& constprop_register (insn
, x
, newcnst
, alter_jumps
))
3094 /* If we find a case where we can't fix the retval REG_EQUAL notes
3095 match the new register, we either have to abandon this replacement
3096 or fix delete_trivially_dead_insns to preserve the setting insn,
3097 or make it delete the REG_EUAQL note, and fix up all passes that
3098 require the REG_EQUAL note there. */
3101 adjusted
= adjust_libcall_notes (x
, newcnst
, insn
, libcall_sp
);
3102 gcc_assert (adjusted
);
3104 if (gcse_file
!= NULL
)
3106 fprintf (gcse_file
, "LOCAL CONST-PROP: Replacing reg %d in ",
3108 fprintf (gcse_file
, "insn %d with constant ",
3110 print_rtl (gcse_file
, newcnst
);
3111 fprintf (gcse_file
, "\n");
3113 local_const_prop_count
++;
3116 else if (newreg
&& newreg
!= x
&& try_replace_reg (x
, newreg
, insn
))
3118 adjust_libcall_notes (x
, newreg
, insn
, libcall_sp
);
3119 if (gcse_file
!= NULL
)
3122 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
3123 REGNO (x
), INSN_UID (insn
));
3124 fprintf (gcse_file
, " with reg %d\n", REGNO (newreg
));
3126 local_copy_prop_count
++;
3133 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3134 their REG_EQUAL notes need updating to reflect that OLDREG has been
3135 replaced with NEWVAL in INSN. Return true if all substitutions could
3138 adjust_libcall_notes (rtx oldreg
, rtx newval
, rtx insn
, rtx
*libcall_sp
)
3142 while ((end
= *libcall_sp
++))
3144 rtx note
= find_reg_equal_equiv_note (end
);
3151 if (reg_set_between_p (newval
, PREV_INSN (insn
), end
))
3155 note
= find_reg_equal_equiv_note (end
);
3158 if (reg_mentioned_p (newval
, XEXP (note
, 0)))
3161 while ((end
= *libcall_sp
++));
3165 XEXP (note
, 0) = simplify_replace_rtx (XEXP (note
, 0), oldreg
, newval
);
3171 #define MAX_NESTED_LIBCALLS 9
3174 local_cprop_pass (int alter_jumps
)
3177 struct reg_use
*reg_used
;
3178 rtx libcall_stack
[MAX_NESTED_LIBCALLS
+ 1], *libcall_sp
;
3179 bool changed
= false;
3181 cselib_init (false);
3182 libcall_sp
= &libcall_stack
[MAX_NESTED_LIBCALLS
];
3184 for (insn
= get_insns (); insn
; insn
= NEXT_INSN (insn
))
3188 rtx note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
3192 gcc_assert (libcall_sp
!= libcall_stack
);
3193 *--libcall_sp
= XEXP (note
, 0);
3195 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
3198 note
= find_reg_equal_equiv_note (insn
);
3202 note_uses (&PATTERN (insn
), local_cprop_find_used_regs
, NULL
);
3204 local_cprop_find_used_regs (&XEXP (note
, 0), NULL
);
3206 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
3207 reg_used
++, reg_use_count
--)
3208 if (do_local_cprop (reg_used
->reg_rtx
, insn
, alter_jumps
,
3214 if (INSN_DELETED_P (insn
))
3217 while (reg_use_count
);
3219 cselib_process_insn (insn
);
3222 /* Global analysis may get into infinite loops for unreachable blocks. */
3223 if (changed
&& alter_jumps
)
3225 delete_unreachable_blocks ();
3226 free_reg_set_mem ();
3227 alloc_reg_set_mem (max_reg_num ());
3228 compute_sets (get_insns ());
3232 /* Forward propagate copies. This includes copies and constants. Return
3233 nonzero if a change was made. */
3236 cprop (int alter_jumps
)
3242 /* Note we start at block 1. */
3243 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3245 if (gcse_file
!= NULL
)
3246 fprintf (gcse_file
, "\n");
3251 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
3253 /* Reset tables used to keep track of what's still valid [since the
3254 start of the block]. */
3255 reset_opr_set_tables ();
3257 for (insn
= BB_HEAD (bb
);
3258 insn
!= NULL
&& insn
!= NEXT_INSN (BB_END (bb
));
3259 insn
= NEXT_INSN (insn
))
3262 changed
|= cprop_insn (insn
, alter_jumps
);
3264 /* Keep track of everything modified by this insn. */
3265 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
3266 call mark_oprs_set if we turned the insn into a NOTE. */
3267 if (! NOTE_P (insn
))
3268 mark_oprs_set (insn
);
3272 if (gcse_file
!= NULL
)
3273 fprintf (gcse_file
, "\n");
3278 /* Similar to get_condition, only the resulting condition must be
3279 valid at JUMP, instead of at EARLIEST.
3281 This differs from noce_get_condition in ifcvt.c in that we prefer not to
3282 settle for the condition variable in the jump instruction being integral.
3283 We prefer to be able to record the value of a user variable, rather than
3284 the value of a temporary used in a condition. This could be solved by
3285 recording the value of *every* register scaned by canonicalize_condition,
3286 but this would require some code reorganization. */
3289 fis_get_condition (rtx jump
)
3291 return get_condition (jump
, NULL
, false, true);
3294 /* Check the comparison COND to see if we can safely form an implicit set from
3295 it. COND is either an EQ or NE comparison. */
3298 implicit_set_cond_p (rtx cond
)
3300 enum machine_mode mode
= GET_MODE (XEXP (cond
, 0));
3301 rtx cst
= XEXP (cond
, 1);
3303 /* We can't perform this optimization if either operand might be or might
3304 contain a signed zero. */
3305 if (HONOR_SIGNED_ZEROS (mode
))
3307 /* It is sufficient to check if CST is or contains a zero. We must
3308 handle float, complex, and vector. If any subpart is a zero, then
3309 the optimization can't be performed. */
3310 /* ??? The complex and vector checks are not implemented yet. We just
3311 always return zero for them. */
3312 if (GET_CODE (cst
) == CONST_DOUBLE
)
3315 REAL_VALUE_FROM_CONST_DOUBLE (d
, cst
);
3316 if (REAL_VALUES_EQUAL (d
, dconst0
))
3323 return gcse_constant_p (cst
);
3326 /* Find the implicit sets of a function. An "implicit set" is a constraint
3327 on the value of a variable, implied by a conditional jump. For example,
3328 following "if (x == 2)", the then branch may be optimized as though the
3329 conditional performed an "explicit set", in this example, "x = 2". This
3330 function records the set patterns that are implicit at the start of each
3334 find_implicit_sets (void)
3336 basic_block bb
, dest
;
3342 /* Check for more than one successor. */
3343 if (EDGE_COUNT (bb
->succs
) > 1)
3345 cond
= fis_get_condition (BB_END (bb
));
3348 && (GET_CODE (cond
) == EQ
|| GET_CODE (cond
) == NE
)
3349 && REG_P (XEXP (cond
, 0))
3350 && REGNO (XEXP (cond
, 0)) >= FIRST_PSEUDO_REGISTER
3351 && implicit_set_cond_p (cond
))
3353 dest
= GET_CODE (cond
) == EQ
? BRANCH_EDGE (bb
)->dest
3354 : FALLTHRU_EDGE (bb
)->dest
;
3356 if (dest
&& EDGE_COUNT (dest
->preds
) == 1
3357 && dest
!= EXIT_BLOCK_PTR
)
3359 new = gen_rtx_SET (VOIDmode
, XEXP (cond
, 0),
3361 implicit_sets
[dest
->index
] = new;
3364 fprintf(gcse_file
, "Implicit set of reg %d in ",
3365 REGNO (XEXP (cond
, 0)));
3366 fprintf(gcse_file
, "basic block %d\n", dest
->index
);
3374 fprintf (gcse_file
, "Found %d implicit sets\n", count
);
3377 /* Perform one copy/constant propagation pass.
3378 PASS is the pass count. If CPROP_JUMPS is true, perform constant
3379 propagation into conditional jumps. If BYPASS_JUMPS is true,
3380 perform conditional jump bypassing optimizations. */
3383 one_cprop_pass (int pass
, int cprop_jumps
, int bypass_jumps
)
3387 global_const_prop_count
= local_const_prop_count
= 0;
3388 global_copy_prop_count
= local_copy_prop_count
= 0;
3390 local_cprop_pass (cprop_jumps
);
3392 /* Determine implicit sets. */
3393 implicit_sets
= xcalloc (last_basic_block
, sizeof (rtx
));
3394 find_implicit_sets ();
3396 alloc_hash_table (max_cuid
, &set_hash_table
, 1);
3397 compute_hash_table (&set_hash_table
);
3399 /* Free implicit_sets before peak usage. */
3400 free (implicit_sets
);
3401 implicit_sets
= NULL
;
3404 dump_hash_table (gcse_file
, "SET", &set_hash_table
);
3405 if (set_hash_table
.n_elems
> 0)
3407 alloc_cprop_mem (last_basic_block
, set_hash_table
.n_elems
);
3408 compute_cprop_data ();
3409 changed
= cprop (cprop_jumps
);
3411 changed
|= bypass_conditional_jumps ();
3415 free_hash_table (&set_hash_table
);
3419 fprintf (gcse_file
, "CPROP of %s, pass %d: %d bytes needed, ",
3420 current_function_name (), pass
, bytes_used
);
3421 fprintf (gcse_file
, "%d local const props, %d local copy props\n\n",
3422 local_const_prop_count
, local_copy_prop_count
);
3423 fprintf (gcse_file
, "%d global const props, %d global copy props\n\n",
3424 global_const_prop_count
, global_copy_prop_count
);
3426 /* Global analysis may get into infinite loops for unreachable blocks. */
3427 if (changed
&& cprop_jumps
)
3428 delete_unreachable_blocks ();
3433 /* Bypass conditional jumps. */
3435 /* The value of last_basic_block at the beginning of the jump_bypass
3436 pass. The use of redirect_edge_and_branch_force may introduce new
3437 basic blocks, but the data flow analysis is only valid for basic
3438 block indices less than bypass_last_basic_block. */
3440 static int bypass_last_basic_block
;
3442 /* Find a set of REGNO to a constant that is available at the end of basic
3443 block BB. Returns NULL if no such set is found. Based heavily upon
3446 static struct expr
*
3447 find_bypass_set (int regno
, int bb
)
3449 struct expr
*result
= 0;
3454 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
3458 if (TEST_BIT (cprop_avout
[bb
], set
->bitmap_index
))
3460 set
= next_set (regno
, set
);
3466 gcc_assert (GET_CODE (set
->expr
) == SET
);
3468 src
= SET_SRC (set
->expr
);
3469 if (gcse_constant_p (src
))
3475 regno
= REGNO (src
);
3481 /* Subroutine of bypass_block that checks whether a pseudo is killed by
3482 any of the instructions inserted on an edge. Jump bypassing places
3483 condition code setters on CFG edges using insert_insn_on_edge. This
3484 function is required to check that our data flow analysis is still
3485 valid prior to commit_edge_insertions. */
3488 reg_killed_on_edge (rtx reg
, edge e
)
3492 for (insn
= e
->insns
.r
; insn
; insn
= NEXT_INSN (insn
))
3493 if (INSN_P (insn
) && reg_set_p (reg
, insn
))
3499 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
3500 basic block BB which has more than one predecessor. If not NULL, SETCC
3501 is the first instruction of BB, which is immediately followed by JUMP_INSN
3502 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
3503 Returns nonzero if a change was made.
3505 During the jump bypassing pass, we may place copies of SETCC instructions
3506 on CFG edges. The following routine must be careful to pay attention to
3507 these inserted insns when performing its transformations. */
3510 bypass_block (basic_block bb
, rtx setcc
, rtx jump
)
3515 int may_be_loop_header
;
3519 insn
= (setcc
!= NULL
) ? setcc
: jump
;
3521 /* Determine set of register uses in INSN. */
3523 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
3524 note
= find_reg_equal_equiv_note (insn
);
3526 find_used_regs (&XEXP (note
, 0), NULL
);
3528 may_be_loop_header
= false;
3529 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3530 if (e
->flags
& EDGE_DFS_BACK
)
3532 may_be_loop_header
= true;
3537 for (ei
= ei_start (bb
->preds
); (e
= ei_safe_edge (ei
)); )
3541 if (e
->flags
& EDGE_COMPLEX
)
3547 /* We can't redirect edges from new basic blocks. */
3548 if (e
->src
->index
>= bypass_last_basic_block
)
3554 /* The irreducible loops created by redirecting of edges entering the
3555 loop from outside would decrease effectiveness of some of the following
3556 optimizations, so prevent this. */
3557 if (may_be_loop_header
3558 && !(e
->flags
& EDGE_DFS_BACK
))
3564 for (i
= 0; i
< reg_use_count
; i
++)
3566 struct reg_use
*reg_used
= ®_use_table
[i
];
3567 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
3568 basic_block dest
, old_dest
;
3572 if (regno
>= max_gcse_regno
)
3575 set
= find_bypass_set (regno
, e
->src
->index
);
3580 /* Check the data flow is valid after edge insertions. */
3581 if (e
->insns
.r
&& reg_killed_on_edge (reg_used
->reg_rtx
, e
))
3584 src
= SET_SRC (pc_set (jump
));
3587 src
= simplify_replace_rtx (src
,
3588 SET_DEST (PATTERN (setcc
)),
3589 SET_SRC (PATTERN (setcc
)));
3591 new = simplify_replace_rtx (src
, reg_used
->reg_rtx
,
3592 SET_SRC (set
->expr
));
3594 /* Jump bypassing may have already placed instructions on
3595 edges of the CFG. We can't bypass an outgoing edge that
3596 has instructions associated with it, as these insns won't
3597 get executed if the incoming edge is redirected. */
3601 edest
= FALLTHRU_EDGE (bb
);
3602 dest
= edest
->insns
.r
? NULL
: edest
->dest
;
3604 else if (GET_CODE (new) == LABEL_REF
)
3608 dest
= BLOCK_FOR_INSN (XEXP (new, 0));
3609 /* Don't bypass edges containing instructions. */
3610 FOR_EACH_EDGE (edest
, ei2
, bb
->succs
)
3611 if (edest
->dest
== dest
&& edest
->insns
.r
)
3620 /* Avoid unification of the edge with other edges from original
3621 branch. We would end up emitting the instruction on "both"
3624 if (dest
&& setcc
&& !CC0_P (SET_DEST (PATTERN (setcc
))))
3629 FOR_EACH_EDGE (e2
, ei2
, e
->src
->succs
)
3630 if (e2
->dest
== dest
)
3640 && dest
!= EXIT_BLOCK_PTR
)
3642 redirect_edge_and_branch_force (e
, dest
);
3644 /* Copy the register setter to the redirected edge.
3645 Don't copy CC0 setters, as CC0 is dead after jump. */
3648 rtx pat
= PATTERN (setcc
);
3649 if (!CC0_P (SET_DEST (pat
)))
3650 insert_insn_on_edge (copy_insn (pat
), e
);
3653 if (gcse_file
!= NULL
)
3655 fprintf (gcse_file
, "JUMP-BYPASS: Proved reg %d "
3656 "in jump_insn %d equals constant ",
3657 regno
, INSN_UID (jump
));
3658 print_rtl (gcse_file
, SET_SRC (set
->expr
));
3659 fprintf (gcse_file
, "\nBypass edge from %d->%d to %d\n",
3660 e
->src
->index
, old_dest
->index
, dest
->index
);
3673 /* Find basic blocks with more than one predecessor that only contain a
3674 single conditional jump. If the result of the comparison is known at
3675 compile-time from any incoming edge, redirect that edge to the
3676 appropriate target. Returns nonzero if a change was made.
3678 This function is now mis-named, because we also handle indirect jumps. */
3681 bypass_conditional_jumps (void)
3689 /* Note we start at block 1. */
3690 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3693 bypass_last_basic_block
= last_basic_block
;
3694 mark_dfs_back_edges ();
3697 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
,
3698 EXIT_BLOCK_PTR
, next_bb
)
3700 /* Check for more than one predecessor. */
3701 if (EDGE_COUNT (bb
->preds
) > 1)
3704 for (insn
= BB_HEAD (bb
);
3705 insn
!= NULL
&& insn
!= NEXT_INSN (BB_END (bb
));
3706 insn
= NEXT_INSN (insn
))
3707 if (NONJUMP_INSN_P (insn
))
3711 if (GET_CODE (PATTERN (insn
)) != SET
)
3714 dest
= SET_DEST (PATTERN (insn
));
3715 if (REG_P (dest
) || CC0_P (dest
))
3720 else if (JUMP_P (insn
))
3722 if ((any_condjump_p (insn
) || computed_jump_p (insn
))
3723 && onlyjump_p (insn
))
3724 changed
|= bypass_block (bb
, setcc
, insn
);
3727 else if (INSN_P (insn
))
3732 /* If we bypassed any register setting insns, we inserted a
3733 copy on the redirected edge. These need to be committed. */
3735 commit_edge_insertions();
3740 /* Compute PRE+LCM working variables. */
3742 /* Local properties of expressions. */
3743 /* Nonzero for expressions that are transparent in the block. */
3744 static sbitmap
*transp
;
3746 /* Nonzero for expressions that are transparent at the end of the block.
3747 This is only zero for expressions killed by abnormal critical edge
3748 created by a calls. */
3749 static sbitmap
*transpout
;
3751 /* Nonzero for expressions that are computed (available) in the block. */
3752 static sbitmap
*comp
;
3754 /* Nonzero for expressions that are locally anticipatable in the block. */
3755 static sbitmap
*antloc
;
3757 /* Nonzero for expressions where this block is an optimal computation
3759 static sbitmap
*pre_optimal
;
3761 /* Nonzero for expressions which are redundant in a particular block. */
3762 static sbitmap
*pre_redundant
;
3764 /* Nonzero for expressions which should be inserted on a specific edge. */
3765 static sbitmap
*pre_insert_map
;
3767 /* Nonzero for expressions which should be deleted in a specific block. */
3768 static sbitmap
*pre_delete_map
;
3770 /* Contains the edge_list returned by pre_edge_lcm. */
3771 static struct edge_list
*edge_list
;
3773 /* Redundant insns. */
3774 static sbitmap pre_redundant_insns
;
3776 /* Allocate vars used for PRE analysis. */
3779 alloc_pre_mem (int n_blocks
, int n_exprs
)
3781 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3782 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3783 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3786 pre_redundant
= NULL
;
3787 pre_insert_map
= NULL
;
3788 pre_delete_map
= NULL
;
3789 ae_kill
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3791 /* pre_insert and pre_delete are allocated later. */
3794 /* Free vars used for PRE analysis. */
3799 sbitmap_vector_free (transp
);
3800 sbitmap_vector_free (comp
);
3802 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
3805 sbitmap_vector_free (pre_optimal
);
3807 sbitmap_vector_free (pre_redundant
);
3809 sbitmap_vector_free (pre_insert_map
);
3811 sbitmap_vector_free (pre_delete_map
);
3813 transp
= comp
= NULL
;
3814 pre_optimal
= pre_redundant
= pre_insert_map
= pre_delete_map
= NULL
;
3817 /* Top level routine to do the dataflow analysis needed by PRE. */
3820 compute_pre_data (void)
3822 sbitmap trapping_expr
;
3826 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
3827 sbitmap_vector_zero (ae_kill
, last_basic_block
);
3829 /* Collect expressions which might trap. */
3830 trapping_expr
= sbitmap_alloc (expr_hash_table
.n_elems
);
3831 sbitmap_zero (trapping_expr
);
3832 for (ui
= 0; ui
< expr_hash_table
.size
; ui
++)
3835 for (e
= expr_hash_table
.table
[ui
]; e
!= NULL
; e
= e
->next_same_hash
)
3836 if (may_trap_p (e
->expr
))
3837 SET_BIT (trapping_expr
, e
->bitmap_index
);
3840 /* Compute ae_kill for each basic block using:
3850 /* If the current block is the destination of an abnormal edge, we
3851 kill all trapping expressions because we won't be able to properly
3852 place the instruction on the edge. So make them neither
3853 anticipatable nor transparent. This is fairly conservative. */
3854 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3855 if (e
->flags
& EDGE_ABNORMAL
)
3857 sbitmap_difference (antloc
[bb
->index
], antloc
[bb
->index
], trapping_expr
);
3858 sbitmap_difference (transp
[bb
->index
], transp
[bb
->index
], trapping_expr
);
3862 sbitmap_a_or_b (ae_kill
[bb
->index
], transp
[bb
->index
], comp
[bb
->index
]);
3863 sbitmap_not (ae_kill
[bb
->index
], ae_kill
[bb
->index
]);
3866 edge_list
= pre_edge_lcm (gcse_file
, expr_hash_table
.n_elems
, transp
, comp
, antloc
,
3867 ae_kill
, &pre_insert_map
, &pre_delete_map
);
3868 sbitmap_vector_free (antloc
);
3870 sbitmap_vector_free (ae_kill
);
3872 sbitmap_free (trapping_expr
);
3877 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
3880 VISITED is a pointer to a working buffer for tracking which BB's have
3881 been visited. It is NULL for the top-level call.
3883 We treat reaching expressions that go through blocks containing the same
3884 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3885 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3886 2 as not reaching. The intent is to improve the probability of finding
3887 only one reaching expression and to reduce register lifetimes by picking
3888 the closest such expression. */
3891 pre_expr_reaches_here_p_work (basic_block occr_bb
, struct expr
*expr
, basic_block bb
, char *visited
)
3896 FOR_EACH_EDGE (pred
, ei
, bb
->preds
)
3898 basic_block pred_bb
= pred
->src
;
3900 if (pred
->src
== ENTRY_BLOCK_PTR
3901 /* Has predecessor has already been visited? */
3902 || visited
[pred_bb
->index
])
3903 ;/* Nothing to do. */
3905 /* Does this predecessor generate this expression? */
3906 else if (TEST_BIT (comp
[pred_bb
->index
], expr
->bitmap_index
))
3908 /* Is this the occurrence we're looking for?
3909 Note that there's only one generating occurrence per block
3910 so we just need to check the block number. */
3911 if (occr_bb
== pred_bb
)
3914 visited
[pred_bb
->index
] = 1;
3916 /* Ignore this predecessor if it kills the expression. */
3917 else if (! TEST_BIT (transp
[pred_bb
->index
], expr
->bitmap_index
))
3918 visited
[pred_bb
->index
] = 1;
3920 /* Neither gen nor kill. */
3923 visited
[pred_bb
->index
] = 1;
3924 if (pre_expr_reaches_here_p_work (occr_bb
, expr
, pred_bb
, visited
))
3929 /* All paths have been checked. */
3933 /* The wrapper for pre_expr_reaches_here_work that ensures that any
3934 memory allocated for that function is returned. */
3937 pre_expr_reaches_here_p (basic_block occr_bb
, struct expr
*expr
, basic_block bb
)
3940 char *visited
= xcalloc (last_basic_block
, 1);
3942 rval
= pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
);
3949 /* Given an expr, generate RTL which we can insert at the end of a BB,
3950 or on an edge. Set the block number of any insns generated to
3954 process_insert_insn (struct expr
*expr
)
3956 rtx reg
= expr
->reaching_reg
;
3957 rtx exp
= copy_rtx (expr
->expr
);
3962 /* If the expression is something that's an operand, like a constant,
3963 just copy it to a register. */
3964 if (general_operand (exp
, GET_MODE (reg
)))
3965 emit_move_insn (reg
, exp
);
3967 /* Otherwise, make a new insn to compute this expression and make sure the
3968 insn will be recognized (this also adds any needed CLOBBERs). Copy the
3969 expression to make sure we don't have any sharing issues. */
3972 rtx insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, exp
));
3974 if (insn_invalid_p (insn
))
3985 /* Add EXPR to the end of basic block BB.
3987 This is used by both the PRE and code hoisting.
3989 For PRE, we want to verify that the expr is either transparent
3990 or locally anticipatable in the target block. This check makes
3991 no sense for code hoisting. */
3994 insert_insn_end_bb (struct expr
*expr
, basic_block bb
, int pre
)
3996 rtx insn
= BB_END (bb
);
3998 rtx reg
= expr
->reaching_reg
;
3999 int regno
= REGNO (reg
);
4002 pat
= process_insert_insn (expr
);
4003 gcc_assert (pat
&& INSN_P (pat
));
4006 while (NEXT_INSN (pat_end
) != NULL_RTX
)
4007 pat_end
= NEXT_INSN (pat_end
);
4009 /* If the last insn is a jump, insert EXPR in front [taking care to
4010 handle cc0, etc. properly]. Similarly we need to care trapping
4011 instructions in presence of non-call exceptions. */
4014 || (NONJUMP_INSN_P (insn
)
4015 && (EDGE_COUNT (bb
->succs
) > 1
4016 || EDGE_SUCC (bb
, 0)->flags
& EDGE_ABNORMAL
)))
4021 /* It should always be the case that we can put these instructions
4022 anywhere in the basic block with performing PRE optimizations.
4024 gcc_assert (!NONJUMP_INSN_P (insn
) || !pre
4025 || TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
4026 || TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
));
4028 /* If this is a jump table, then we can't insert stuff here. Since
4029 we know the previous real insn must be the tablejump, we insert
4030 the new instruction just before the tablejump. */
4031 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
4032 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
4033 insn
= prev_real_insn (insn
);
4036 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4037 if cc0 isn't set. */
4038 note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
4040 insn
= XEXP (note
, 0);
4043 rtx maybe_cc0_setter
= prev_nonnote_insn (insn
);
4044 if (maybe_cc0_setter
4045 && INSN_P (maybe_cc0_setter
)
4046 && sets_cc0_p (PATTERN (maybe_cc0_setter
)))
4047 insn
= maybe_cc0_setter
;
4050 /* FIXME: What if something in cc0/jump uses value set in new insn? */
4051 new_insn
= emit_insn_before_noloc (pat
, insn
);
4054 /* Likewise if the last insn is a call, as will happen in the presence
4055 of exception handling. */
4056 else if (CALL_P (insn
)
4057 && (EDGE_COUNT (bb
->succs
) > 1 || EDGE_SUCC (bb
, 0)->flags
& EDGE_ABNORMAL
))
4059 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
4060 we search backward and place the instructions before the first
4061 parameter is loaded. Do this for everyone for consistency and a
4062 presumption that we'll get better code elsewhere as well.
4064 It should always be the case that we can put these instructions
4065 anywhere in the basic block with performing PRE optimizations.
4069 || TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
4070 || TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
));
4072 /* Since different machines initialize their parameter registers
4073 in different orders, assume nothing. Collect the set of all
4074 parameter registers. */
4075 insn
= find_first_parameter_load (insn
, BB_HEAD (bb
));
4077 /* If we found all the parameter loads, then we want to insert
4078 before the first parameter load.
4080 If we did not find all the parameter loads, then we might have
4081 stopped on the head of the block, which could be a CODE_LABEL.
4082 If we inserted before the CODE_LABEL, then we would be putting
4083 the insn in the wrong basic block. In that case, put the insn
4084 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
4085 while (LABEL_P (insn
)
4086 || NOTE_INSN_BASIC_BLOCK_P (insn
))
4087 insn
= NEXT_INSN (insn
);
4089 new_insn
= emit_insn_before_noloc (pat
, insn
);
4092 new_insn
= emit_insn_after_noloc (pat
, insn
);
4098 add_label_notes (PATTERN (pat
), new_insn
);
4099 note_stores (PATTERN (pat
), record_set_info
, pat
);
4103 pat
= NEXT_INSN (pat
);
4106 gcse_create_count
++;
4110 fprintf (gcse_file
, "PRE/HOIST: end of bb %d, insn %d, ",
4111 bb
->index
, INSN_UID (new_insn
));
4112 fprintf (gcse_file
, "copying expression %d to reg %d\n",
4113 expr
->bitmap_index
, regno
);
4117 /* Insert partially redundant expressions on edges in the CFG to make
4118 the expressions fully redundant. */
4121 pre_edge_insert (struct edge_list
*edge_list
, struct expr
**index_map
)
4123 int e
, i
, j
, num_edges
, set_size
, did_insert
= 0;
4126 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
4127 if it reaches any of the deleted expressions. */
4129 set_size
= pre_insert_map
[0]->size
;
4130 num_edges
= NUM_EDGES (edge_list
);
4131 inserted
= sbitmap_vector_alloc (num_edges
, expr_hash_table
.n_elems
);
4132 sbitmap_vector_zero (inserted
, num_edges
);
4134 for (e
= 0; e
< num_edges
; e
++)
4137 basic_block bb
= INDEX_EDGE_PRED_BB (edge_list
, e
);
4139 for (i
= indx
= 0; i
< set_size
; i
++, indx
+= SBITMAP_ELT_BITS
)
4141 SBITMAP_ELT_TYPE insert
= pre_insert_map
[e
]->elms
[i
];
4143 for (j
= indx
; insert
&& j
< (int) expr_hash_table
.n_elems
; j
++, insert
>>= 1)
4144 if ((insert
& 1) != 0 && index_map
[j
]->reaching_reg
!= NULL_RTX
)
4146 struct expr
*expr
= index_map
[j
];
4149 /* Now look at each deleted occurrence of this expression. */
4150 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4152 if (! occr
->deleted_p
)
4155 /* Insert this expression on this edge if if it would
4156 reach the deleted occurrence in BB. */
4157 if (!TEST_BIT (inserted
[e
], j
))
4160 edge eg
= INDEX_EDGE (edge_list
, e
);
4162 /* We can't insert anything on an abnormal and
4163 critical edge, so we insert the insn at the end of
4164 the previous block. There are several alternatives
4165 detailed in Morgans book P277 (sec 10.5) for
4166 handling this situation. This one is easiest for
4169 if (eg
->flags
& EDGE_ABNORMAL
)
4170 insert_insn_end_bb (index_map
[j
], bb
, 0);
4173 insn
= process_insert_insn (index_map
[j
]);
4174 insert_insn_on_edge (insn
, eg
);
4179 fprintf (gcse_file
, "PRE/HOIST: edge (%d,%d), ",
4181 INDEX_EDGE_SUCC_BB (edge_list
, e
)->index
);
4182 fprintf (gcse_file
, "copy expression %d\n",
4183 expr
->bitmap_index
);
4186 update_ld_motion_stores (expr
);
4187 SET_BIT (inserted
[e
], j
);
4189 gcse_create_count
++;
4196 sbitmap_vector_free (inserted
);
4200 /* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
4201 Given "old_reg <- expr" (INSN), instead of adding after it
4202 reaching_reg <- old_reg
4203 it's better to do the following:
4204 reaching_reg <- expr
4205 old_reg <- reaching_reg
4206 because this way copy propagation can discover additional PRE
4207 opportunities. But if this fails, we try the old way.
4208 When "expr" is a store, i.e.
4209 given "MEM <- old_reg", instead of adding after it
4210 reaching_reg <- old_reg
4211 it's better to add it before as follows:
4212 reaching_reg <- old_reg
4213 MEM <- reaching_reg. */
4216 pre_insert_copy_insn (struct expr
*expr
, rtx insn
)
4218 rtx reg
= expr
->reaching_reg
;
4219 int regno
= REGNO (reg
);
4220 int indx
= expr
->bitmap_index
;
4221 rtx pat
= PATTERN (insn
);
4226 /* This block matches the logic in hash_scan_insn. */
4227 switch (GET_CODE (pat
))
4234 /* Search through the parallel looking for the set whose
4235 source was the expression that we're interested in. */
4237 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
4239 rtx x
= XVECEXP (pat
, 0, i
);
4240 if (GET_CODE (x
) == SET
4241 && expr_equiv_p (SET_SRC (x
), expr
->expr
))
4253 if (REG_P (SET_DEST (set
)))
4255 old_reg
= SET_DEST (set
);
4256 /* Check if we can modify the set destination in the original insn. */
4257 if (validate_change (insn
, &SET_DEST (set
), reg
, 0))
4259 new_insn
= gen_move_insn (old_reg
, reg
);
4260 new_insn
= emit_insn_after (new_insn
, insn
);
4262 /* Keep register set table up to date. */
4263 replace_one_set (REGNO (old_reg
), insn
, new_insn
);
4264 record_one_set (regno
, insn
);
4268 new_insn
= gen_move_insn (reg
, old_reg
);
4269 new_insn
= emit_insn_after (new_insn
, insn
);
4271 /* Keep register set table up to date. */
4272 record_one_set (regno
, new_insn
);
4275 else /* This is possible only in case of a store to memory. */
4277 old_reg
= SET_SRC (set
);
4278 new_insn
= gen_move_insn (reg
, old_reg
);
4280 /* Check if we can modify the set source in the original insn. */
4281 if (validate_change (insn
, &SET_SRC (set
), reg
, 0))
4282 new_insn
= emit_insn_before (new_insn
, insn
);
4284 new_insn
= emit_insn_after (new_insn
, insn
);
4286 /* Keep register set table up to date. */
4287 record_one_set (regno
, new_insn
);
4290 gcse_create_count
++;
4294 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
4295 BLOCK_NUM (insn
), INSN_UID (new_insn
), indx
,
4296 INSN_UID (insn
), regno
);
4299 /* Copy available expressions that reach the redundant expression
4300 to `reaching_reg'. */
4303 pre_insert_copies (void)
4305 unsigned int i
, added_copy
;
4310 /* For each available expression in the table, copy the result to
4311 `reaching_reg' if the expression reaches a deleted one.
4313 ??? The current algorithm is rather brute force.
4314 Need to do some profiling. */
4316 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4317 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
4319 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
4320 we don't want to insert a copy here because the expression may not
4321 really be redundant. So only insert an insn if the expression was
4322 deleted. This test also avoids further processing if the
4323 expression wasn't deleted anywhere. */
4324 if (expr
->reaching_reg
== NULL
)
4327 /* Set when we add a copy for that expression. */
4330 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4332 if (! occr
->deleted_p
)
4335 for (avail
= expr
->avail_occr
; avail
!= NULL
; avail
= avail
->next
)
4337 rtx insn
= avail
->insn
;
4339 /* No need to handle this one if handled already. */
4340 if (avail
->copied_p
)
4343 /* Don't handle this one if it's a redundant one. */
4344 if (TEST_BIT (pre_redundant_insns
, INSN_CUID (insn
)))
4347 /* Or if the expression doesn't reach the deleted one. */
4348 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail
->insn
),
4350 BLOCK_FOR_INSN (occr
->insn
)))
4355 /* Copy the result of avail to reaching_reg. */
4356 pre_insert_copy_insn (expr
, insn
);
4357 avail
->copied_p
= 1;
4362 update_ld_motion_stores (expr
);
4366 /* Emit move from SRC to DEST noting the equivalence with expression computed
4369 gcse_emit_move_after (rtx src
, rtx dest
, rtx insn
)
4372 rtx set
= single_set (insn
), set2
;
4376 /* This should never fail since we're creating a reg->reg copy
4377 we've verified to be valid. */
4379 new = emit_insn_after (gen_move_insn (dest
, src
), insn
);
4381 /* Note the equivalence for local CSE pass. */
4382 set2
= single_set (new);
4383 if (!set2
|| !rtx_equal_p (SET_DEST (set2
), dest
))
4385 if ((note
= find_reg_equal_equiv_note (insn
)))
4386 eqv
= XEXP (note
, 0);
4388 eqv
= SET_SRC (set
);
4390 set_unique_reg_note (new, REG_EQUAL
, copy_insn_1 (eqv
));
4395 /* Delete redundant computations.
4396 Deletion is done by changing the insn to copy the `reaching_reg' of
4397 the expression into the result of the SET. It is left to later passes
4398 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
4400 Returns nonzero if a change is made. */
4411 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4412 for (expr
= expr_hash_table
.table
[i
];
4414 expr
= expr
->next_same_hash
)
4416 int indx
= expr
->bitmap_index
;
4418 /* We only need to search antic_occr since we require
4421 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4423 rtx insn
= occr
->insn
;
4425 basic_block bb
= BLOCK_FOR_INSN (insn
);
4427 /* We only delete insns that have a single_set. */
4428 if (TEST_BIT (pre_delete_map
[bb
->index
], indx
)
4429 && (set
= single_set (insn
)) != 0)
4431 /* Create a pseudo-reg to store the result of reaching
4432 expressions into. Get the mode for the new pseudo from
4433 the mode of the original destination pseudo. */
4434 if (expr
->reaching_reg
== NULL
)
4436 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
4438 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
4440 occr
->deleted_p
= 1;
4441 SET_BIT (pre_redundant_insns
, INSN_CUID (insn
));
4448 "PRE: redundant insn %d (expression %d) in ",
4449 INSN_UID (insn
), indx
);
4450 fprintf (gcse_file
, "bb %d, reaching reg is %d\n",
4451 bb
->index
, REGNO (expr
->reaching_reg
));
4460 /* Perform GCSE optimizations using PRE.
4461 This is called by one_pre_gcse_pass after all the dataflow analysis
4464 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
4465 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
4466 Compiler Design and Implementation.
4468 ??? A new pseudo reg is created to hold the reaching expression. The nice
4469 thing about the classical approach is that it would try to use an existing
4470 reg. If the register can't be adequately optimized [i.e. we introduce
4471 reload problems], one could add a pass here to propagate the new register
4474 ??? We don't handle single sets in PARALLELs because we're [currently] not
4475 able to copy the rest of the parallel when we insert copies to create full
4476 redundancies from partial redundancies. However, there's no reason why we
4477 can't handle PARALLELs in the cases where there are no partial
4484 int did_insert
, changed
;
4485 struct expr
**index_map
;
4488 /* Compute a mapping from expression number (`bitmap_index') to
4489 hash table entry. */
4491 index_map
= xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
4492 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4493 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
4494 index_map
[expr
->bitmap_index
] = expr
;
4496 /* Reset bitmap used to track which insns are redundant. */
4497 pre_redundant_insns
= sbitmap_alloc (max_cuid
);
4498 sbitmap_zero (pre_redundant_insns
);
4500 /* Delete the redundant insns first so that
4501 - we know what register to use for the new insns and for the other
4502 ones with reaching expressions
4503 - we know which insns are redundant when we go to create copies */
4505 changed
= pre_delete ();
4507 did_insert
= pre_edge_insert (edge_list
, index_map
);
4509 /* In other places with reaching expressions, copy the expression to the
4510 specially allocated pseudo-reg that reaches the redundant expr. */
4511 pre_insert_copies ();
4514 commit_edge_insertions ();
4519 sbitmap_free (pre_redundant_insns
);
4523 /* Top level routine to perform one PRE GCSE pass.
4525 Return nonzero if a change was made. */
4528 one_pre_gcse_pass (int pass
)
4532 gcse_subst_count
= 0;
4533 gcse_create_count
= 0;
4535 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
4536 add_noreturn_fake_exit_edges ();
4538 compute_ld_motion_mems ();
4540 compute_hash_table (&expr_hash_table
);
4541 trim_ld_motion_mems ();
4543 dump_hash_table (gcse_file
, "Expression", &expr_hash_table
);
4545 if (expr_hash_table
.n_elems
> 0)
4547 alloc_pre_mem (last_basic_block
, expr_hash_table
.n_elems
);
4548 compute_pre_data ();
4549 changed
|= pre_gcse ();
4550 free_edge_list (edge_list
);
4555 remove_fake_exit_edges ();
4556 free_hash_table (&expr_hash_table
);
4560 fprintf (gcse_file
, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
4561 current_function_name (), pass
, bytes_used
);
4562 fprintf (gcse_file
, "%d substs, %d insns created\n",
4563 gcse_subst_count
, gcse_create_count
);
4569 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
4570 If notes are added to an insn which references a CODE_LABEL, the
4571 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
4572 because the following loop optimization pass requires them. */
4574 /* ??? This is very similar to the loop.c add_label_notes function. We
4575 could probably share code here. */
4577 /* ??? If there was a jump optimization pass after gcse and before loop,
4578 then we would not need to do this here, because jump would add the
4579 necessary REG_LABEL notes. */
4582 add_label_notes (rtx x
, rtx insn
)
4584 enum rtx_code code
= GET_CODE (x
);
4588 if (code
== LABEL_REF
&& !LABEL_REF_NONLOCAL_P (x
))
4590 /* This code used to ignore labels that referred to dispatch tables to
4591 avoid flow generating (slightly) worse code.
4593 We no longer ignore such label references (see LABEL_REF handling in
4594 mark_jump_label for additional information). */
4596 REG_NOTES (insn
) = gen_rtx_INSN_LIST (REG_LABEL
, XEXP (x
, 0),
4598 if (LABEL_P (XEXP (x
, 0)))
4599 LABEL_NUSES (XEXP (x
, 0))++;
4603 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
4606 add_label_notes (XEXP (x
, i
), insn
);
4607 else if (fmt
[i
] == 'E')
4608 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4609 add_label_notes (XVECEXP (x
, i
, j
), insn
);
4613 /* Compute transparent outgoing information for each block.
4615 An expression is transparent to an edge unless it is killed by
4616 the edge itself. This can only happen with abnormal control flow,
4617 when the edge is traversed through a call. This happens with
4618 non-local labels and exceptions.
4620 This would not be necessary if we split the edge. While this is
4621 normally impossible for abnormal critical edges, with some effort
4622 it should be possible with exception handling, since we still have
4623 control over which handler should be invoked. But due to increased
4624 EH table sizes, this may not be worthwhile. */
4627 compute_transpout (void)
4633 sbitmap_vector_ones (transpout
, last_basic_block
);
4637 /* Note that flow inserted a nop a the end of basic blocks that
4638 end in call instructions for reasons other than abnormal
4640 if (! CALL_P (BB_END (bb
)))
4643 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4644 for (expr
= expr_hash_table
.table
[i
]; expr
; expr
= expr
->next_same_hash
)
4645 if (MEM_P (expr
->expr
))
4647 if (GET_CODE (XEXP (expr
->expr
, 0)) == SYMBOL_REF
4648 && CONSTANT_POOL_ADDRESS_P (XEXP (expr
->expr
, 0)))
4651 /* ??? Optimally, we would use interprocedural alias
4652 analysis to determine if this mem is actually killed
4654 RESET_BIT (transpout
[bb
->index
], expr
->bitmap_index
);
4659 /* Code Hoisting variables and subroutines. */
4661 /* Very busy expressions. */
4662 static sbitmap
*hoist_vbein
;
4663 static sbitmap
*hoist_vbeout
;
4665 /* Hoistable expressions. */
4666 static sbitmap
*hoist_exprs
;
4668 /* ??? We could compute post dominators and run this algorithm in
4669 reverse to perform tail merging, doing so would probably be
4670 more effective than the tail merging code in jump.c.
4672 It's unclear if tail merging could be run in parallel with
4673 code hoisting. It would be nice. */
4675 /* Allocate vars used for code hoisting analysis. */
4678 alloc_code_hoist_mem (int n_blocks
, int n_exprs
)
4680 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4681 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4682 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4684 hoist_vbein
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4685 hoist_vbeout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4686 hoist_exprs
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4687 transpout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4690 /* Free vars used for code hoisting analysis. */
4693 free_code_hoist_mem (void)
4695 sbitmap_vector_free (antloc
);
4696 sbitmap_vector_free (transp
);
4697 sbitmap_vector_free (comp
);
4699 sbitmap_vector_free (hoist_vbein
);
4700 sbitmap_vector_free (hoist_vbeout
);
4701 sbitmap_vector_free (hoist_exprs
);
4702 sbitmap_vector_free (transpout
);
4704 free_dominance_info (CDI_DOMINATORS
);
4707 /* Compute the very busy expressions at entry/exit from each block.
4709 An expression is very busy if all paths from a given point
4710 compute the expression. */
4713 compute_code_hoist_vbeinout (void)
4715 int changed
, passes
;
4718 sbitmap_vector_zero (hoist_vbeout
, last_basic_block
);
4719 sbitmap_vector_zero (hoist_vbein
, last_basic_block
);
4728 /* We scan the blocks in the reverse order to speed up
4730 FOR_EACH_BB_REVERSE (bb
)
4732 changed
|= sbitmap_a_or_b_and_c_cg (hoist_vbein
[bb
->index
], antloc
[bb
->index
],
4733 hoist_vbeout
[bb
->index
], transp
[bb
->index
]);
4734 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
4735 sbitmap_intersection_of_succs (hoist_vbeout
[bb
->index
], hoist_vbein
, bb
->index
);
4742 fprintf (gcse_file
, "hoisting vbeinout computation: %d passes\n", passes
);
4745 /* Top level routine to do the dataflow analysis needed by code hoisting. */
4748 compute_code_hoist_data (void)
4750 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
4751 compute_transpout ();
4752 compute_code_hoist_vbeinout ();
4753 calculate_dominance_info (CDI_DOMINATORS
);
4755 fprintf (gcse_file
, "\n");
4758 /* Determine if the expression identified by EXPR_INDEX would
4759 reach BB unimpared if it was placed at the end of EXPR_BB.
4761 It's unclear exactly what Muchnick meant by "unimpared". It seems
4762 to me that the expression must either be computed or transparent in
4763 *every* block in the path(s) from EXPR_BB to BB. Any other definition
4764 would allow the expression to be hoisted out of loops, even if
4765 the expression wasn't a loop invariant.
4767 Contrast this to reachability for PRE where an expression is
4768 considered reachable if *any* path reaches instead of *all*
4772 hoist_expr_reaches_here_p (basic_block expr_bb
, int expr_index
, basic_block bb
, char *visited
)
4776 int visited_allocated_locally
= 0;
4779 if (visited
== NULL
)
4781 visited_allocated_locally
= 1;
4782 visited
= xcalloc (last_basic_block
, 1);
4785 FOR_EACH_EDGE (pred
, ei
, bb
->preds
)
4787 basic_block pred_bb
= pred
->src
;
4789 if (pred
->src
== ENTRY_BLOCK_PTR
)
4791 else if (pred_bb
== expr_bb
)
4793 else if (visited
[pred_bb
->index
])
4796 /* Does this predecessor generate this expression? */
4797 else if (TEST_BIT (comp
[pred_bb
->index
], expr_index
))
4799 else if (! TEST_BIT (transp
[pred_bb
->index
], expr_index
))
4805 visited
[pred_bb
->index
] = 1;
4806 if (! hoist_expr_reaches_here_p (expr_bb
, expr_index
,
4811 if (visited_allocated_locally
)
4814 return (pred
== NULL
);
4817 /* Actually perform code hoisting. */
4822 basic_block bb
, dominated
;
4824 unsigned int domby_len
;
4826 struct expr
**index_map
;
4829 sbitmap_vector_zero (hoist_exprs
, last_basic_block
);
4831 /* Compute a mapping from expression number (`bitmap_index') to
4832 hash table entry. */
4834 index_map
= xcalloc (expr_hash_table
.n_elems
, sizeof (struct expr
*));
4835 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4836 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
4837 index_map
[expr
->bitmap_index
] = expr
;
4839 /* Walk over each basic block looking for potentially hoistable
4840 expressions, nothing gets hoisted from the entry block. */
4844 int insn_inserted_p
;
4846 domby_len
= get_dominated_by (CDI_DOMINATORS
, bb
, &domby
);
4847 /* Examine each expression that is very busy at the exit of this
4848 block. These are the potentially hoistable expressions. */
4849 for (i
= 0; i
< hoist_vbeout
[bb
->index
]->n_bits
; i
++)
4853 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
)
4854 && TEST_BIT (transpout
[bb
->index
], i
))
4856 /* We've found a potentially hoistable expression, now
4857 we look at every block BB dominates to see if it
4858 computes the expression. */
4859 for (j
= 0; j
< domby_len
; j
++)
4861 dominated
= domby
[j
];
4862 /* Ignore self dominance. */
4863 if (bb
== dominated
)
4865 /* We've found a dominated block, now see if it computes
4866 the busy expression and whether or not moving that
4867 expression to the "beginning" of that block is safe. */
4868 if (!TEST_BIT (antloc
[dominated
->index
], i
))
4871 /* Note if the expression would reach the dominated block
4872 unimpared if it was placed at the end of BB.
4874 Keep track of how many times this expression is hoistable
4875 from a dominated block into BB. */
4876 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
4880 /* If we found more than one hoistable occurrence of this
4881 expression, then note it in the bitmap of expressions to
4882 hoist. It makes no sense to hoist things which are computed
4883 in only one BB, and doing so tends to pessimize register
4884 allocation. One could increase this value to try harder
4885 to avoid any possible code expansion due to register
4886 allocation issues; however experiments have shown that
4887 the vast majority of hoistable expressions are only movable
4888 from two successors, so raising this threshold is likely
4889 to nullify any benefit we get from code hoisting. */
4892 SET_BIT (hoist_exprs
[bb
->index
], i
);
4897 /* If we found nothing to hoist, then quit now. */
4904 /* Loop over all the hoistable expressions. */
4905 for (i
= 0; i
< hoist_exprs
[bb
->index
]->n_bits
; i
++)
4907 /* We want to insert the expression into BB only once, so
4908 note when we've inserted it. */
4909 insn_inserted_p
= 0;
4911 /* These tests should be the same as the tests above. */
4912 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
))
4914 /* We've found a potentially hoistable expression, now
4915 we look at every block BB dominates to see if it
4916 computes the expression. */
4917 for (j
= 0; j
< domby_len
; j
++)
4919 dominated
= domby
[j
];
4920 /* Ignore self dominance. */
4921 if (bb
== dominated
)
4924 /* We've found a dominated block, now see if it computes
4925 the busy expression and whether or not moving that
4926 expression to the "beginning" of that block is safe. */
4927 if (!TEST_BIT (antloc
[dominated
->index
], i
))
4930 /* The expression is computed in the dominated block and
4931 it would be safe to compute it at the start of the
4932 dominated block. Now we have to determine if the
4933 expression would reach the dominated block if it was
4934 placed at the end of BB. */
4935 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
4937 struct expr
*expr
= index_map
[i
];
4938 struct occr
*occr
= expr
->antic_occr
;
4942 /* Find the right occurrence of this expression. */
4943 while (BLOCK_FOR_INSN (occr
->insn
) != dominated
&& occr
)
4948 set
= single_set (insn
);
4951 /* Create a pseudo-reg to store the result of reaching
4952 expressions into. Get the mode for the new pseudo
4953 from the mode of the original destination pseudo. */
4954 if (expr
->reaching_reg
== NULL
)
4956 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
4958 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
4960 occr
->deleted_p
= 1;
4961 if (!insn_inserted_p
)
4963 insert_insn_end_bb (index_map
[i
], bb
, 0);
4964 insn_inserted_p
= 1;
4976 /* Top level routine to perform one code hoisting (aka unification) pass
4978 Return nonzero if a change was made. */
4981 one_code_hoisting_pass (void)
4985 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
4986 compute_hash_table (&expr_hash_table
);
4988 dump_hash_table (gcse_file
, "Code Hosting Expressions", &expr_hash_table
);
4990 if (expr_hash_table
.n_elems
> 0)
4992 alloc_code_hoist_mem (last_basic_block
, expr_hash_table
.n_elems
);
4993 compute_code_hoist_data ();
4995 free_code_hoist_mem ();
4998 free_hash_table (&expr_hash_table
);
5003 /* Here we provide the things required to do store motion towards
5004 the exit. In order for this to be effective, gcse also needed to
5005 be taught how to move a load when it is kill only by a store to itself.
5010 void foo(float scale)
5012 for (i=0; i<10; i++)
5016 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
5017 the load out since its live around the loop, and stored at the bottom
5020 The 'Load Motion' referred to and implemented in this file is
5021 an enhancement to gcse which when using edge based lcm, recognizes
5022 this situation and allows gcse to move the load out of the loop.
5024 Once gcse has hoisted the load, store motion can then push this
5025 load towards the exit, and we end up with no loads or stores of 'i'
5028 /* This will search the ldst list for a matching expression. If it
5029 doesn't find one, we create one and initialize it. */
5031 static struct ls_expr
*
5034 int do_not_record_p
= 0;
5035 struct ls_expr
* ptr
;
5038 hash
= hash_rtx (x
, GET_MODE (x
), &do_not_record_p
,
5039 NULL
, /*have_reg_qty=*/false);
5041 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
5042 if (ptr
->hash_index
== hash
&& expr_equiv_p (ptr
->pattern
, x
))
5045 ptr
= xmalloc (sizeof (struct ls_expr
));
5047 ptr
->next
= pre_ldst_mems
;
5050 ptr
->pattern_regs
= NULL_RTX
;
5051 ptr
->loads
= NULL_RTX
;
5052 ptr
->stores
= NULL_RTX
;
5053 ptr
->reaching_reg
= NULL_RTX
;
5056 ptr
->hash_index
= hash
;
5057 pre_ldst_mems
= ptr
;
5062 /* Free up an individual ldst entry. */
5065 free_ldst_entry (struct ls_expr
* ptr
)
5067 free_INSN_LIST_list (& ptr
->loads
);
5068 free_INSN_LIST_list (& ptr
->stores
);
5073 /* Free up all memory associated with the ldst list. */
5076 free_ldst_mems (void)
5078 while (pre_ldst_mems
)
5080 struct ls_expr
* tmp
= pre_ldst_mems
;
5082 pre_ldst_mems
= pre_ldst_mems
->next
;
5084 free_ldst_entry (tmp
);
5087 pre_ldst_mems
= NULL
;
5090 /* Dump debugging info about the ldst list. */
5093 print_ldst_list (FILE * file
)
5095 struct ls_expr
* ptr
;
5097 fprintf (file
, "LDST list: \n");
5099 for (ptr
= first_ls_expr(); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
5101 fprintf (file
, " Pattern (%3d): ", ptr
->index
);
5103 print_rtl (file
, ptr
->pattern
);
5105 fprintf (file
, "\n Loads : ");
5108 print_rtl (file
, ptr
->loads
);
5110 fprintf (file
, "(nil)");
5112 fprintf (file
, "\n Stores : ");
5115 print_rtl (file
, ptr
->stores
);
5117 fprintf (file
, "(nil)");
5119 fprintf (file
, "\n\n");
5122 fprintf (file
, "\n");
5125 /* Returns 1 if X is in the list of ldst only expressions. */
5127 static struct ls_expr
*
5128 find_rtx_in_ldst (rtx x
)
5130 struct ls_expr
* ptr
;
5132 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
5133 if (expr_equiv_p (ptr
->pattern
, x
) && ! ptr
->invalid
)
5139 /* Assign each element of the list of mems a monotonically increasing value. */
5142 enumerate_ldsts (void)
5144 struct ls_expr
* ptr
;
5147 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
5153 /* Return first item in the list. */
5155 static inline struct ls_expr
*
5156 first_ls_expr (void)
5158 return pre_ldst_mems
;
5161 /* Return the next item in the list after the specified one. */
5163 static inline struct ls_expr
*
5164 next_ls_expr (struct ls_expr
* ptr
)
5169 /* Load Motion for loads which only kill themselves. */
5171 /* Return true if x is a simple MEM operation, with no registers or
5172 side effects. These are the types of loads we consider for the
5173 ld_motion list, otherwise we let the usual aliasing take care of it. */
5181 if (MEM_VOLATILE_P (x
))
5184 if (GET_MODE (x
) == BLKmode
)
5187 /* If we are handling exceptions, we must be careful with memory references
5188 that may trap. If we are not, the behavior is undefined, so we may just
5190 if (flag_non_call_exceptions
&& may_trap_p (x
))
5193 if (side_effects_p (x
))
5196 /* Do not consider function arguments passed on stack. */
5197 if (reg_mentioned_p (stack_pointer_rtx
, x
))
5200 if (flag_float_store
&& FLOAT_MODE_P (GET_MODE (x
)))
5206 /* Make sure there isn't a buried reference in this pattern anywhere.
5207 If there is, invalidate the entry for it since we're not capable
5208 of fixing it up just yet.. We have to be sure we know about ALL
5209 loads since the aliasing code will allow all entries in the
5210 ld_motion list to not-alias itself. If we miss a load, we will get
5211 the wrong value since gcse might common it and we won't know to
5215 invalidate_any_buried_refs (rtx x
)
5219 struct ls_expr
* ptr
;
5221 /* Invalidate it in the list. */
5222 if (MEM_P (x
) && simple_mem (x
))
5224 ptr
= ldst_entry (x
);
5228 /* Recursively process the insn. */
5229 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
5231 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0; i
--)
5234 invalidate_any_buried_refs (XEXP (x
, i
));
5235 else if (fmt
[i
] == 'E')
5236 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5237 invalidate_any_buried_refs (XVECEXP (x
, i
, j
));
5241 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
5242 being defined as MEM loads and stores to symbols, with no side effects
5243 and no registers in the expression. For a MEM destination, we also
5244 check that the insn is still valid if we replace the destination with a
5245 REG, as is done in update_ld_motion_stores. If there are any uses/defs
5246 which don't match this criteria, they are invalidated and trimmed out
5250 compute_ld_motion_mems (void)
5252 struct ls_expr
* ptr
;
5256 pre_ldst_mems
= NULL
;
5260 for (insn
= BB_HEAD (bb
);
5261 insn
&& insn
!= NEXT_INSN (BB_END (bb
));
5262 insn
= NEXT_INSN (insn
))
5266 if (GET_CODE (PATTERN (insn
)) == SET
)
5268 rtx src
= SET_SRC (PATTERN (insn
));
5269 rtx dest
= SET_DEST (PATTERN (insn
));
5271 /* Check for a simple LOAD... */
5272 if (MEM_P (src
) && simple_mem (src
))
5274 ptr
= ldst_entry (src
);
5276 ptr
->loads
= alloc_INSN_LIST (insn
, ptr
->loads
);
5282 /* Make sure there isn't a buried load somewhere. */
5283 invalidate_any_buried_refs (src
);
5286 /* Check for stores. Don't worry about aliased ones, they
5287 will block any movement we might do later. We only care
5288 about this exact pattern since those are the only
5289 circumstance that we will ignore the aliasing info. */
5290 if (MEM_P (dest
) && simple_mem (dest
))
5292 ptr
= ldst_entry (dest
);
5295 && GET_CODE (src
) != ASM_OPERANDS
5296 /* Check for REG manually since want_to_gcse_p
5297 returns 0 for all REGs. */
5298 && can_assign_to_reg_p (src
))
5299 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
5305 invalidate_any_buried_refs (PATTERN (insn
));
5311 /* Remove any references that have been either invalidated or are not in the
5312 expression list for pre gcse. */
5315 trim_ld_motion_mems (void)
5317 struct ls_expr
* * last
= & pre_ldst_mems
;
5318 struct ls_expr
* ptr
= pre_ldst_mems
;
5324 /* Delete if entry has been made invalid. */
5327 /* Delete if we cannot find this mem in the expression list. */
5328 unsigned int hash
= ptr
->hash_index
% expr_hash_table
.size
;
5330 for (expr
= expr_hash_table
.table
[hash
];
5332 expr
= expr
->next_same_hash
)
5333 if (expr_equiv_p (expr
->expr
, ptr
->pattern
))
5337 expr
= (struct expr
*) 0;
5341 /* Set the expression field if we are keeping it. */
5349 free_ldst_entry (ptr
);
5354 /* Show the world what we've found. */
5355 if (gcse_file
&& pre_ldst_mems
!= NULL
)
5356 print_ldst_list (gcse_file
);
5359 /* This routine will take an expression which we are replacing with
5360 a reaching register, and update any stores that are needed if
5361 that expression is in the ld_motion list. Stores are updated by
5362 copying their SRC to the reaching register, and then storing
5363 the reaching register into the store location. These keeps the
5364 correct value in the reaching register for the loads. */
5367 update_ld_motion_stores (struct expr
* expr
)
5369 struct ls_expr
* mem_ptr
;
5371 if ((mem_ptr
= find_rtx_in_ldst (expr
->expr
)))
5373 /* We can try to find just the REACHED stores, but is shouldn't
5374 matter to set the reaching reg everywhere... some might be
5375 dead and should be eliminated later. */
5377 /* We replace (set mem expr) with (set reg expr) (set mem reg)
5378 where reg is the reaching reg used in the load. We checked in
5379 compute_ld_motion_mems that we can replace (set mem expr) with
5380 (set reg expr) in that insn. */
5381 rtx list
= mem_ptr
->stores
;
5383 for ( ; list
!= NULL_RTX
; list
= XEXP (list
, 1))
5385 rtx insn
= XEXP (list
, 0);
5386 rtx pat
= PATTERN (insn
);
5387 rtx src
= SET_SRC (pat
);
5388 rtx reg
= expr
->reaching_reg
;
5391 /* If we've already copied it, continue. */
5392 if (expr
->reaching_reg
== src
)
5397 fprintf (gcse_file
, "PRE: store updated with reaching reg ");
5398 print_rtl (gcse_file
, expr
->reaching_reg
);
5399 fprintf (gcse_file
, ":\n ");
5400 print_inline_rtx (gcse_file
, insn
, 8);
5401 fprintf (gcse_file
, "\n");
5404 copy
= gen_move_insn ( reg
, copy_rtx (SET_SRC (pat
)));
5405 new = emit_insn_before (copy
, insn
);
5406 record_one_set (REGNO (reg
), new);
5407 SET_SRC (pat
) = reg
;
5409 /* un-recognize this pattern since it's probably different now. */
5410 INSN_CODE (insn
) = -1;
5411 gcse_create_count
++;
5416 /* Store motion code. */
5418 #define ANTIC_STORE_LIST(x) ((x)->loads)
5419 #define AVAIL_STORE_LIST(x) ((x)->stores)
5420 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
5422 /* This is used to communicate the target bitvector we want to use in the
5423 reg_set_info routine when called via the note_stores mechanism. */
5424 static int * regvec
;
5426 /* And current insn, for the same routine. */
5427 static rtx compute_store_table_current_insn
;
5429 /* Used in computing the reverse edge graph bit vectors. */
5430 static sbitmap
* st_antloc
;
5432 /* Global holding the number of store expressions we are dealing with. */
5433 static int num_stores
;
5435 /* Checks to set if we need to mark a register set. Called from
5439 reg_set_info (rtx dest
, rtx setter ATTRIBUTE_UNUSED
,
5442 sbitmap bb_reg
= data
;
5444 if (GET_CODE (dest
) == SUBREG
)
5445 dest
= SUBREG_REG (dest
);
5449 regvec
[REGNO (dest
)] = INSN_UID (compute_store_table_current_insn
);
5451 SET_BIT (bb_reg
, REGNO (dest
));
5455 /* Clear any mark that says that this insn sets dest. Called from
5459 reg_clear_last_set (rtx dest
, rtx setter ATTRIBUTE_UNUSED
,
5462 int *dead_vec
= data
;
5464 if (GET_CODE (dest
) == SUBREG
)
5465 dest
= SUBREG_REG (dest
);
5468 dead_vec
[REGNO (dest
)] == INSN_UID (compute_store_table_current_insn
))
5469 dead_vec
[REGNO (dest
)] = 0;
5472 /* Return zero if some of the registers in list X are killed
5473 due to set of registers in bitmap REGS_SET. */
5476 store_ops_ok (rtx x
, int *regs_set
)
5480 for (; x
; x
= XEXP (x
, 1))
5483 if (regs_set
[REGNO(reg
)])
5490 /* Returns a list of registers mentioned in X. */
5492 extract_mentioned_regs (rtx x
)
5494 return extract_mentioned_regs_helper (x
, NULL_RTX
);
5497 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
5500 extract_mentioned_regs_helper (rtx x
, rtx accum
)
5506 /* Repeat is used to turn tail-recursion into iteration. */
5512 code
= GET_CODE (x
);
5516 return alloc_EXPR_LIST (0, x
, accum
);
5526 /* We do not run this function with arguments having side effects. */
5545 i
= GET_RTX_LENGTH (code
) - 1;
5546 fmt
= GET_RTX_FORMAT (code
);
5552 rtx tem
= XEXP (x
, i
);
5554 /* If we are about to do the last recursive call
5555 needed at this level, change it into iteration. */
5562 accum
= extract_mentioned_regs_helper (tem
, accum
);
5564 else if (fmt
[i
] == 'E')
5568 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
5569 accum
= extract_mentioned_regs_helper (XVECEXP (x
, i
, j
), accum
);
5576 /* Determine whether INSN is MEM store pattern that we will consider moving.
5577 REGS_SET_BEFORE is bitmap of registers set before (and including) the
5578 current insn, REGS_SET_AFTER is bitmap of registers set after (and
5579 including) the insn in this basic block. We must be passing through BB from
5580 head to end, as we are using this fact to speed things up.
5582 The results are stored this way:
5584 -- the first anticipatable expression is added into ANTIC_STORE_LIST
5585 -- if the processed expression is not anticipatable, NULL_RTX is added
5586 there instead, so that we can use it as indicator that no further
5587 expression of this type may be anticipatable
5588 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
5589 consequently, all of them but this head are dead and may be deleted.
5590 -- if the expression is not available, the insn due to that it fails to be
5591 available is stored in reaching_reg.
5593 The things are complicated a bit by fact that there already may be stores
5594 to the same MEM from other blocks; also caller must take care of the
5595 necessary cleanup of the temporary markers after end of the basic block.
5599 find_moveable_store (rtx insn
, int *regs_set_before
, int *regs_set_after
)
5601 struct ls_expr
* ptr
;
5603 int check_anticipatable
, check_available
;
5604 basic_block bb
= BLOCK_FOR_INSN (insn
);
5606 set
= single_set (insn
);
5610 dest
= SET_DEST (set
);
5612 if (! MEM_P (dest
) || MEM_VOLATILE_P (dest
)
5613 || GET_MODE (dest
) == BLKmode
)
5616 if (side_effects_p (dest
))
5619 /* If we are handling exceptions, we must be careful with memory references
5620 that may trap. If we are not, the behavior is undefined, so we may just
5622 if (flag_non_call_exceptions
&& may_trap_p (dest
))
5625 /* Even if the destination cannot trap, the source may. In this case we'd
5626 need to handle updating the REG_EH_REGION note. */
5627 if (find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
))
5630 ptr
= ldst_entry (dest
);
5631 if (!ptr
->pattern_regs
)
5632 ptr
->pattern_regs
= extract_mentioned_regs (dest
);
5634 /* Do not check for anticipatability if we either found one anticipatable
5635 store already, or tested for one and found out that it was killed. */
5636 check_anticipatable
= 0;
5637 if (!ANTIC_STORE_LIST (ptr
))
5638 check_anticipatable
= 1;
5641 tmp
= XEXP (ANTIC_STORE_LIST (ptr
), 0);
5643 && BLOCK_FOR_INSN (tmp
) != bb
)
5644 check_anticipatable
= 1;
5646 if (check_anticipatable
)
5648 if (store_killed_before (dest
, ptr
->pattern_regs
, insn
, bb
, regs_set_before
))
5652 ANTIC_STORE_LIST (ptr
) = alloc_INSN_LIST (tmp
,
5653 ANTIC_STORE_LIST (ptr
));
5656 /* It is not necessary to check whether store is available if we did
5657 it successfully before; if we failed before, do not bother to check
5658 until we reach the insn that caused us to fail. */
5659 check_available
= 0;
5660 if (!AVAIL_STORE_LIST (ptr
))
5661 check_available
= 1;
5664 tmp
= XEXP (AVAIL_STORE_LIST (ptr
), 0);
5665 if (BLOCK_FOR_INSN (tmp
) != bb
)
5666 check_available
= 1;
5668 if (check_available
)
5670 /* Check that we have already reached the insn at that the check
5671 failed last time. */
5672 if (LAST_AVAIL_CHECK_FAILURE (ptr
))
5674 for (tmp
= BB_END (bb
);
5675 tmp
!= insn
&& tmp
!= LAST_AVAIL_CHECK_FAILURE (ptr
);
5676 tmp
= PREV_INSN (tmp
))
5679 check_available
= 0;
5682 check_available
= store_killed_after (dest
, ptr
->pattern_regs
, insn
,
5684 &LAST_AVAIL_CHECK_FAILURE (ptr
));
5686 if (!check_available
)
5687 AVAIL_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
, AVAIL_STORE_LIST (ptr
));
5690 /* Find available and anticipatable stores. */
5693 compute_store_table (void)
5699 int *last_set_in
, *already_set
;
5700 struct ls_expr
* ptr
, **prev_next_ptr_ptr
;
5702 max_gcse_regno
= max_reg_num ();
5704 reg_set_in_block
= sbitmap_vector_alloc (last_basic_block
,
5706 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
5708 last_set_in
= xcalloc (max_gcse_regno
, sizeof (int));
5709 already_set
= xmalloc (sizeof (int) * max_gcse_regno
);
5711 /* Find all the stores we care about. */
5714 /* First compute the registers set in this block. */
5715 regvec
= last_set_in
;
5717 for (insn
= BB_HEAD (bb
);
5718 insn
!= NEXT_INSN (BB_END (bb
));
5719 insn
= NEXT_INSN (insn
))
5721 if (! INSN_P (insn
))
5726 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
5727 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
5729 last_set_in
[regno
] = INSN_UID (insn
);
5730 SET_BIT (reg_set_in_block
[bb
->index
], regno
);
5734 pat
= PATTERN (insn
);
5735 compute_store_table_current_insn
= insn
;
5736 note_stores (pat
, reg_set_info
, reg_set_in_block
[bb
->index
]);
5739 /* Now find the stores. */
5740 memset (already_set
, 0, sizeof (int) * max_gcse_regno
);
5741 regvec
= already_set
;
5742 for (insn
= BB_HEAD (bb
);
5743 insn
!= NEXT_INSN (BB_END (bb
));
5744 insn
= NEXT_INSN (insn
))
5746 if (! INSN_P (insn
))
5751 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
5752 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
5753 already_set
[regno
] = 1;
5756 pat
= PATTERN (insn
);
5757 note_stores (pat
, reg_set_info
, NULL
);
5759 /* Now that we've marked regs, look for stores. */
5760 find_moveable_store (insn
, already_set
, last_set_in
);
5762 /* Unmark regs that are no longer set. */
5763 compute_store_table_current_insn
= insn
;
5764 note_stores (pat
, reg_clear_last_set
, last_set_in
);
5767 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
5768 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
)
5769 && last_set_in
[regno
] == INSN_UID (insn
))
5770 last_set_in
[regno
] = 0;
5774 #ifdef ENABLE_CHECKING
5775 /* last_set_in should now be all-zero. */
5776 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
5777 gcc_assert (!last_set_in
[regno
]);
5780 /* Clear temporary marks. */
5781 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
5783 LAST_AVAIL_CHECK_FAILURE(ptr
) = NULL_RTX
;
5784 if (ANTIC_STORE_LIST (ptr
)
5785 && (tmp
= XEXP (ANTIC_STORE_LIST (ptr
), 0)) == NULL_RTX
)
5786 ANTIC_STORE_LIST (ptr
) = XEXP (ANTIC_STORE_LIST (ptr
), 1);
5790 /* Remove the stores that are not available anywhere, as there will
5791 be no opportunity to optimize them. */
5792 for (ptr
= pre_ldst_mems
, prev_next_ptr_ptr
= &pre_ldst_mems
;
5794 ptr
= *prev_next_ptr_ptr
)
5796 if (!AVAIL_STORE_LIST (ptr
))
5798 *prev_next_ptr_ptr
= ptr
->next
;
5799 free_ldst_entry (ptr
);
5802 prev_next_ptr_ptr
= &ptr
->next
;
5805 ret
= enumerate_ldsts ();
5809 fprintf (gcse_file
, "ST_avail and ST_antic (shown under loads..)\n");
5810 print_ldst_list (gcse_file
);
5818 /* Check to see if the load X is aliased with STORE_PATTERN.
5819 AFTER is true if we are checking the case when STORE_PATTERN occurs
5823 load_kills_store (rtx x
, rtx store_pattern
, int after
)
5826 return anti_dependence (x
, store_pattern
);
5828 return true_dependence (store_pattern
, GET_MODE (store_pattern
), x
,
5832 /* Go through the entire insn X, looking for any loads which might alias
5833 STORE_PATTERN. Return true if found.
5834 AFTER is true if we are checking the case when STORE_PATTERN occurs
5835 after the insn X. */
5838 find_loads (rtx x
, rtx store_pattern
, int after
)
5847 if (GET_CODE (x
) == SET
)
5852 if (load_kills_store (x
, store_pattern
, after
))
5856 /* Recursively process the insn. */
5857 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
5859 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0 && !ret
; i
--)
5862 ret
|= find_loads (XEXP (x
, i
), store_pattern
, after
);
5863 else if (fmt
[i
] == 'E')
5864 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5865 ret
|= find_loads (XVECEXP (x
, i
, j
), store_pattern
, after
);
5870 /* Check if INSN kills the store pattern X (is aliased with it).
5871 AFTER is true if we are checking the case when store X occurs
5872 after the insn. Return true if it it does. */
5875 store_killed_in_insn (rtx x
, rtx x_regs
, rtx insn
, int after
)
5877 rtx reg
, base
, note
;
5884 /* A normal or pure call might read from pattern,
5885 but a const call will not. */
5886 if (! CONST_OR_PURE_CALL_P (insn
) || pure_call_p (insn
))
5889 /* But even a const call reads its parameters. Check whether the
5890 base of some of registers used in mem is stack pointer. */
5891 for (reg
= x_regs
; reg
; reg
= XEXP (reg
, 1))
5893 base
= find_base_term (XEXP (reg
, 0));
5895 || (GET_CODE (base
) == ADDRESS
5896 && GET_MODE (base
) == Pmode
5897 && XEXP (base
, 0) == stack_pointer_rtx
))
5904 if (GET_CODE (PATTERN (insn
)) == SET
)
5906 rtx pat
= PATTERN (insn
);
5907 rtx dest
= SET_DEST (pat
);
5909 if (GET_CODE (dest
) == ZERO_EXTRACT
)
5910 dest
= XEXP (dest
, 0);
5912 /* Check for memory stores to aliased objects. */
5914 && !expr_equiv_p (dest
, x
))
5918 if (output_dependence (dest
, x
))
5923 if (output_dependence (x
, dest
))
5927 if (find_loads (SET_SRC (pat
), x
, after
))
5930 else if (find_loads (PATTERN (insn
), x
, after
))
5933 /* If this insn has a REG_EQUAL or REG_EQUIV note referencing a memory
5934 location aliased with X, then this insn kills X. */
5935 note
= find_reg_equal_equiv_note (insn
);
5938 note
= XEXP (note
, 0);
5940 /* However, if the note represents a must alias rather than a may
5941 alias relationship, then it does not kill X. */
5942 if (expr_equiv_p (note
, x
))
5945 /* See if there are any aliased loads in the note. */
5946 return find_loads (note
, x
, after
);
5949 /* Returns true if the expression X is loaded or clobbered on or after INSN
5950 within basic block BB. REGS_SET_AFTER is bitmap of registers set in
5951 or after the insn. X_REGS is list of registers mentioned in X. If the store
5952 is killed, return the last insn in that it occurs in FAIL_INSN. */
5955 store_killed_after (rtx x
, rtx x_regs
, rtx insn
, basic_block bb
,
5956 int *regs_set_after
, rtx
*fail_insn
)
5958 rtx last
= BB_END (bb
), act
;
5960 if (!store_ops_ok (x_regs
, regs_set_after
))
5962 /* We do not know where it will happen. */
5964 *fail_insn
= NULL_RTX
;
5968 /* Scan from the end, so that fail_insn is determined correctly. */
5969 for (act
= last
; act
!= PREV_INSN (insn
); act
= PREV_INSN (act
))
5970 if (store_killed_in_insn (x
, x_regs
, act
, false))
5980 /* Returns true if the expression X is loaded or clobbered on or before INSN
5981 within basic block BB. X_REGS is list of registers mentioned in X.
5982 REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
5984 store_killed_before (rtx x
, rtx x_regs
, rtx insn
, basic_block bb
,
5985 int *regs_set_before
)
5987 rtx first
= BB_HEAD (bb
);
5989 if (!store_ops_ok (x_regs
, regs_set_before
))
5992 for ( ; insn
!= PREV_INSN (first
); insn
= PREV_INSN (insn
))
5993 if (store_killed_in_insn (x
, x_regs
, insn
, true))
5999 /* Fill in available, anticipatable, transparent and kill vectors in
6000 STORE_DATA, based on lists of available and anticipatable stores. */
6002 build_store_vectors (void)
6005 int *regs_set_in_block
;
6007 struct ls_expr
* ptr
;
6010 /* Build the gen_vector. This is any store in the table which is not killed
6011 by aliasing later in its block. */
6012 ae_gen
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6013 sbitmap_vector_zero (ae_gen
, last_basic_block
);
6015 st_antloc
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6016 sbitmap_vector_zero (st_antloc
, last_basic_block
);
6018 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6020 for (st
= AVAIL_STORE_LIST (ptr
); st
!= NULL
; st
= XEXP (st
, 1))
6022 insn
= XEXP (st
, 0);
6023 bb
= BLOCK_FOR_INSN (insn
);
6025 /* If we've already seen an available expression in this block,
6026 we can delete this one (It occurs earlier in the block). We'll
6027 copy the SRC expression to an unused register in case there
6028 are any side effects. */
6029 if (TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
6031 rtx r
= gen_reg_rtx (GET_MODE (ptr
->pattern
));
6033 fprintf (gcse_file
, "Removing redundant store:\n");
6034 replace_store_insn (r
, XEXP (st
, 0), bb
, ptr
);
6037 SET_BIT (ae_gen
[bb
->index
], ptr
->index
);
6040 for (st
= ANTIC_STORE_LIST (ptr
); st
!= NULL
; st
= XEXP (st
, 1))
6042 insn
= XEXP (st
, 0);
6043 bb
= BLOCK_FOR_INSN (insn
);
6044 SET_BIT (st_antloc
[bb
->index
], ptr
->index
);
6048 ae_kill
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6049 sbitmap_vector_zero (ae_kill
, last_basic_block
);
6051 transp
= sbitmap_vector_alloc (last_basic_block
, num_stores
);
6052 sbitmap_vector_zero (transp
, last_basic_block
);
6053 regs_set_in_block
= xmalloc (sizeof (int) * max_gcse_regno
);
6057 for (regno
= 0; regno
< max_gcse_regno
; regno
++)
6058 regs_set_in_block
[regno
] = TEST_BIT (reg_set_in_block
[bb
->index
], regno
);
6060 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6062 if (store_killed_after (ptr
->pattern
, ptr
->pattern_regs
, BB_HEAD (bb
),
6063 bb
, regs_set_in_block
, NULL
))
6065 /* It should not be necessary to consider the expression
6066 killed if it is both anticipatable and available. */
6067 if (!TEST_BIT (st_antloc
[bb
->index
], ptr
->index
)
6068 || !TEST_BIT (ae_gen
[bb
->index
], ptr
->index
))
6069 SET_BIT (ae_kill
[bb
->index
], ptr
->index
);
6072 SET_BIT (transp
[bb
->index
], ptr
->index
);
6076 free (regs_set_in_block
);
6080 dump_sbitmap_vector (gcse_file
, "st_antloc", "", st_antloc
, last_basic_block
);
6081 dump_sbitmap_vector (gcse_file
, "st_kill", "", ae_kill
, last_basic_block
);
6082 dump_sbitmap_vector (gcse_file
, "Transpt", "", transp
, last_basic_block
);
6083 dump_sbitmap_vector (gcse_file
, "st_avloc", "", ae_gen
, last_basic_block
);
6087 /* Insert an instruction at the beginning of a basic block, and update
6088 the BB_HEAD if needed. */
6091 insert_insn_start_bb (rtx insn
, basic_block bb
)
6093 /* Insert at start of successor block. */
6094 rtx prev
= PREV_INSN (BB_HEAD (bb
));
6095 rtx before
= BB_HEAD (bb
);
6098 if (! LABEL_P (before
)
6099 && (! NOTE_P (before
)
6100 || NOTE_LINE_NUMBER (before
) != NOTE_INSN_BASIC_BLOCK
))
6103 if (prev
== BB_END (bb
))
6105 before
= NEXT_INSN (before
);
6108 insn
= emit_insn_after_noloc (insn
, prev
);
6112 fprintf (gcse_file
, "STORE_MOTION insert store at start of BB %d:\n",
6114 print_inline_rtx (gcse_file
, insn
, 6);
6115 fprintf (gcse_file
, "\n");
6119 /* This routine will insert a store on an edge. EXPR is the ldst entry for
6120 the memory reference, and E is the edge to insert it on. Returns nonzero
6121 if an edge insertion was performed. */
6124 insert_store (struct ls_expr
* expr
, edge e
)
6131 /* We did all the deleted before this insert, so if we didn't delete a
6132 store, then we haven't set the reaching reg yet either. */
6133 if (expr
->reaching_reg
== NULL_RTX
)
6136 if (e
->flags
& EDGE_FAKE
)
6139 reg
= expr
->reaching_reg
;
6140 insn
= gen_move_insn (copy_rtx (expr
->pattern
), reg
);
6142 /* If we are inserting this expression on ALL predecessor edges of a BB,
6143 insert it at the start of the BB, and reset the insert bits on the other
6144 edges so we don't try to insert it on the other edges. */
6146 FOR_EACH_EDGE (tmp
, ei
, e
->dest
->preds
)
6147 if (!(tmp
->flags
& EDGE_FAKE
))
6149 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
6151 gcc_assert (index
!= EDGE_INDEX_NO_EDGE
);
6152 if (! TEST_BIT (pre_insert_map
[index
], expr
->index
))
6156 /* If tmp is NULL, we found an insertion on every edge, blank the
6157 insertion vector for these edges, and insert at the start of the BB. */
6158 if (!tmp
&& bb
!= EXIT_BLOCK_PTR
)
6160 FOR_EACH_EDGE (tmp
, ei
, e
->dest
->preds
)
6162 int index
= EDGE_INDEX (edge_list
, tmp
->src
, tmp
->dest
);
6163 RESET_BIT (pre_insert_map
[index
], expr
->index
);
6165 insert_insn_start_bb (insn
, bb
);
6169 /* We can't put stores in the front of blocks pointed to by abnormal
6170 edges since that may put a store where one didn't used to be. */
6171 gcc_assert (!(e
->flags
& EDGE_ABNORMAL
));
6173 insert_insn_on_edge (insn
, e
);
6177 fprintf (gcse_file
, "STORE_MOTION insert insn on edge (%d, %d):\n",
6178 e
->src
->index
, e
->dest
->index
);
6179 print_inline_rtx (gcse_file
, insn
, 6);
6180 fprintf (gcse_file
, "\n");
6186 /* Remove any REG_EQUAL or REG_EQUIV notes containing a reference to the
6187 memory location in SMEXPR set in basic block BB.
6189 This could be rather expensive. */
6192 remove_reachable_equiv_notes (basic_block bb
, struct ls_expr
*smexpr
)
6194 edge_iterator
*stack
, ei
;
6197 sbitmap visited
= sbitmap_alloc (last_basic_block
);
6198 rtx last
, insn
, note
;
6199 rtx mem
= smexpr
->pattern
;
6201 stack
= xmalloc (sizeof (edge_iterator
) * n_basic_blocks
);
6203 ei
= ei_start (bb
->succs
);
6205 sbitmap_zero (visited
);
6207 act
= (EDGE_COUNT (ei_container (ei
)) > 0 ? EDGE_I (ei_container (ei
), 0) : NULL
);
6215 sbitmap_free (visited
);
6218 act
= ei_edge (stack
[--sp
]);
6222 if (bb
== EXIT_BLOCK_PTR
6223 || TEST_BIT (visited
, bb
->index
))
6227 act
= (! ei_end_p (ei
)) ? ei_edge (ei
) : NULL
;
6230 SET_BIT (visited
, bb
->index
);
6232 if (TEST_BIT (st_antloc
[bb
->index
], smexpr
->index
))
6234 for (last
= ANTIC_STORE_LIST (smexpr
);
6235 BLOCK_FOR_INSN (XEXP (last
, 0)) != bb
;
6236 last
= XEXP (last
, 1))
6238 last
= XEXP (last
, 0);
6241 last
= NEXT_INSN (BB_END (bb
));
6243 for (insn
= BB_HEAD (bb
); insn
!= last
; insn
= NEXT_INSN (insn
))
6246 note
= find_reg_equal_equiv_note (insn
);
6247 if (!note
|| !expr_equiv_p (XEXP (note
, 0), mem
))
6251 fprintf (gcse_file
, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6253 remove_note (insn
, note
);
6258 act
= (! ei_end_p (ei
)) ? ei_edge (ei
) : NULL
;
6260 if (EDGE_COUNT (bb
->succs
) > 0)
6264 ei
= ei_start (bb
->succs
);
6265 act
= (EDGE_COUNT (ei_container (ei
)) > 0 ? EDGE_I (ei_container (ei
), 0) : NULL
);
6270 /* This routine will replace a store with a SET to a specified register. */
6273 replace_store_insn (rtx reg
, rtx del
, basic_block bb
, struct ls_expr
*smexpr
)
6275 rtx insn
, mem
, note
, set
, ptr
, pair
;
6277 mem
= smexpr
->pattern
;
6278 insn
= gen_move_insn (reg
, SET_SRC (single_set (del
)));
6279 insn
= emit_insn_after (insn
, del
);
6284 "STORE_MOTION delete insn in BB %d:\n ", bb
->index
);
6285 print_inline_rtx (gcse_file
, del
, 6);
6286 fprintf (gcse_file
, "\nSTORE MOTION replaced with insn:\n ");
6287 print_inline_rtx (gcse_file
, insn
, 6);
6288 fprintf (gcse_file
, "\n");
6291 for (ptr
= ANTIC_STORE_LIST (smexpr
); ptr
; ptr
= XEXP (ptr
, 1))
6292 if (XEXP (ptr
, 0) == del
)
6294 XEXP (ptr
, 0) = insn
;
6298 /* Move the notes from the deleted insn to its replacement, and patch
6299 up the LIBCALL notes. */
6300 REG_NOTES (insn
) = REG_NOTES (del
);
6302 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
6305 pair
= XEXP (note
, 0);
6306 note
= find_reg_note (pair
, REG_LIBCALL
, NULL_RTX
);
6307 XEXP (note
, 0) = insn
;
6309 note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
6312 pair
= XEXP (note
, 0);
6313 note
= find_reg_note (pair
, REG_RETVAL
, NULL_RTX
);
6314 XEXP (note
, 0) = insn
;
6319 /* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
6320 they are no longer accurate provided that they are reached by this
6321 definition, so drop them. */
6322 for (; insn
!= NEXT_INSN (BB_END (bb
)); insn
= NEXT_INSN (insn
))
6325 set
= single_set (insn
);
6328 if (expr_equiv_p (SET_DEST (set
), mem
))
6330 note
= find_reg_equal_equiv_note (insn
);
6331 if (!note
|| !expr_equiv_p (XEXP (note
, 0), mem
))
6335 fprintf (gcse_file
, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6337 remove_note (insn
, note
);
6339 remove_reachable_equiv_notes (bb
, smexpr
);
6343 /* Delete a store, but copy the value that would have been stored into
6344 the reaching_reg for later storing. */
6347 delete_store (struct ls_expr
* expr
, basic_block bb
)
6351 if (expr
->reaching_reg
== NULL_RTX
)
6352 expr
->reaching_reg
= gen_reg_rtx (GET_MODE (expr
->pattern
));
6354 reg
= expr
->reaching_reg
;
6356 for (i
= AVAIL_STORE_LIST (expr
); i
; i
= XEXP (i
, 1))
6359 if (BLOCK_FOR_INSN (del
) == bb
)
6361 /* We know there is only one since we deleted redundant
6362 ones during the available computation. */
6363 replace_store_insn (reg
, del
, bb
, expr
);
6369 /* Free memory used by store motion. */
6372 free_store_memory (void)
6377 sbitmap_vector_free (ae_gen
);
6379 sbitmap_vector_free (ae_kill
);
6381 sbitmap_vector_free (transp
);
6383 sbitmap_vector_free (st_antloc
);
6385 sbitmap_vector_free (pre_insert_map
);
6387 sbitmap_vector_free (pre_delete_map
);
6388 if (reg_set_in_block
)
6389 sbitmap_vector_free (reg_set_in_block
);
6391 ae_gen
= ae_kill
= transp
= st_antloc
= NULL
;
6392 pre_insert_map
= pre_delete_map
= reg_set_in_block
= NULL
;
6395 /* Perform store motion. Much like gcse, except we move expressions the
6396 other way by looking at the flowgraph in reverse. */
6403 struct ls_expr
* ptr
;
6404 int update_flow
= 0;
6408 fprintf (gcse_file
, "before store motion\n");
6409 print_rtl (gcse_file
, get_insns ());
6412 init_alias_analysis ();
6414 /* Find all the available and anticipatable stores. */
6415 num_stores
= compute_store_table ();
6416 if (num_stores
== 0)
6418 sbitmap_vector_free (reg_set_in_block
);
6419 end_alias_analysis ();
6423 /* Now compute kill & transp vectors. */
6424 build_store_vectors ();
6425 add_noreturn_fake_exit_edges ();
6426 connect_infinite_loops_to_exit ();
6428 edge_list
= pre_edge_rev_lcm (gcse_file
, num_stores
, transp
, ae_gen
,
6429 st_antloc
, ae_kill
, &pre_insert_map
,
6432 /* Now we want to insert the new stores which are going to be needed. */
6433 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
6435 /* If any of the edges we have above are abnormal, we can't move this
6437 for (x
= NUM_EDGES (edge_list
) - 1; x
>= 0; x
--)
6438 if (TEST_BIT (pre_insert_map
[x
], ptr
->index
)
6439 && (INDEX_EDGE (edge_list
, x
)->flags
& EDGE_ABNORMAL
))
6444 if (gcse_file
!= NULL
)
6446 "Can't replace store %d: abnormal edge from %d to %d\n",
6447 ptr
->index
, INDEX_EDGE (edge_list
, x
)->src
->index
,
6448 INDEX_EDGE (edge_list
, x
)->dest
->index
);
6452 /* Now we want to insert the new stores which are going to be needed. */
6455 if (TEST_BIT (pre_delete_map
[bb
->index
], ptr
->index
))
6456 delete_store (ptr
, bb
);
6458 for (x
= 0; x
< NUM_EDGES (edge_list
); x
++)
6459 if (TEST_BIT (pre_insert_map
[x
], ptr
->index
))
6460 update_flow
|= insert_store (ptr
, INDEX_EDGE (edge_list
, x
));
6464 commit_edge_insertions ();
6466 free_store_memory ();
6467 free_edge_list (edge_list
);
6468 remove_fake_exit_edges ();
6469 end_alias_analysis ();
6473 /* Entry point for jump bypassing optimization pass. */
6476 bypass_jumps (FILE *file
)
6480 /* We do not construct an accurate cfg in functions which call
6481 setjmp, so just punt to be safe. */
6482 if (current_function_calls_setjmp
)
6485 /* For calling dump_foo fns from gdb. */
6486 debug_stderr
= stderr
;
6489 /* Identify the basic block information for this function, including
6490 successors and predecessors. */
6491 max_gcse_regno
= max_reg_num ();
6494 dump_flow_info (file
);
6496 /* Return if there's nothing to do, or it is too expensive. */
6497 if (n_basic_blocks
<= 1 || is_too_expensive (_ ("jump bypassing disabled")))
6500 gcc_obstack_init (&gcse_obstack
);
6503 /* We need alias. */
6504 init_alias_analysis ();
6506 /* Record where pseudo-registers are set. This data is kept accurate
6507 during each pass. ??? We could also record hard-reg information here
6508 [since it's unchanging], however it is currently done during hash table
6511 It may be tempting to compute MEM set information here too, but MEM sets
6512 will be subject to code motion one day and thus we need to compute
6513 information about memory sets when we build the hash tables. */
6515 alloc_reg_set_mem (max_gcse_regno
);
6516 compute_sets (get_insns ());
6518 max_gcse_regno
= max_reg_num ();
6519 alloc_gcse_mem (get_insns ());
6520 changed
= one_cprop_pass (MAX_GCSE_PASSES
+ 2, 1, 1);
6525 fprintf (file
, "BYPASS of %s: %d basic blocks, ",
6526 current_function_name (), n_basic_blocks
);
6527 fprintf (file
, "%d bytes\n\n", bytes_used
);
6530 obstack_free (&gcse_obstack
, NULL
);
6531 free_reg_set_mem ();
6533 /* We are finished with alias. */
6534 end_alias_analysis ();
6535 allocate_reg_info (max_reg_num (), FALSE
, FALSE
);
6540 /* Return true if the graph is too expensive to optimize. PASS is the
6541 optimization about to be performed. */
6544 is_too_expensive (const char *pass
)
6546 /* Trying to perform global optimizations on flow graphs which have
6547 a high connectivity will take a long time and is unlikely to be
6548 particularly useful.
6550 In normal circumstances a cfg should have about twice as many
6551 edges as blocks. But we do not want to punish small functions
6552 which have a couple switch statements. Rather than simply
6553 threshold the number of blocks, uses something with a more
6554 graceful degradation. */
6555 if (n_edges
> 20000 + n_basic_blocks
* 4)
6557 if (warn_disabled_optimization
)
6558 warning ("%s: %d basic blocks and %d edges/basic block",
6559 pass
, n_basic_blocks
, n_edges
/ n_basic_blocks
);
6564 /* If allocating memory for the cprop bitmap would take up too much
6565 storage it's better just to disable the optimization. */
6567 * SBITMAP_SET_SIZE (max_reg_num ())
6568 * sizeof (SBITMAP_ELT_TYPE
)) > MAX_GCSE_MEMORY
)
6570 if (warn_disabled_optimization
)
6571 warning ("%s: %d basic blocks and %d registers",
6572 pass
, n_basic_blocks
, max_reg_num ());
6580 #include "gt-gcse.h"