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, 51 Franklin Street, Fifth Floor, Boston, MA
24 - reordering of memory allocation and freeing to be more space efficient
25 - do rough calc of how many regs are needed in each block, and a rough
26 calc of how many regs are available in each class and use that to
27 throttle back the code in cases where RTX_COST is minimal.
28 - a store to the same address as a load does not kill the load if the
29 source of the store is also the destination of the load. Handling this
30 allows more load motion, particularly out of loops.
31 - ability to realloc sbitmap vectors would allow one initial computation
32 of reg_set_in_block with only subsequent additions, rather than
33 recomputing it for each pass
37 /* References searched while implementing this.
39 Compilers Principles, Techniques and Tools
43 Global Optimization by Suppression of Partial Redundancies
45 communications of the acm, Vol. 22, Num. 2, Feb. 1979
47 A Portable Machine-Independent Global Optimizer - Design and Measurements
49 Stanford Ph.D. thesis, Dec. 1983
51 A Fast Algorithm for Code Movement Optimization
53 SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988
55 A Solution to a Problem with Morel and Renvoise's
56 Global Optimization by Suppression of Partial Redundancies
57 K-H Drechsler, M.P. Stadel
58 ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988
60 Practical Adaptation of the Global Optimization
61 Algorithm of Morel and Renvoise
63 ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991
65 Efficiently Computing Static Single Assignment Form and the Control
67 R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck
68 ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991
71 J. Knoop, O. Ruthing, B. Steffen
72 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
74 What's In a Region? Or Computing Control Dependence Regions in Near-Linear
75 Time for Reducible Flow Control
77 ACM Letters on Programming Languages and Systems,
78 Vol. 2, Num. 1-4, Mar-Dec 1993
80 An Efficient Representation for Sparse Sets
81 Preston Briggs, Linda Torczon
82 ACM Letters on Programming Languages and Systems,
83 Vol. 2, Num. 1-4, Mar-Dec 1993
85 A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion
86 K-H Drechsler, M.P. Stadel
87 ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993
89 Partial Dead Code Elimination
90 J. Knoop, O. Ruthing, B. Steffen
91 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
93 Effective Partial Redundancy Elimination
94 P. Briggs, K.D. Cooper
95 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
97 The Program Structure Tree: Computing Control Regions in Linear Time
98 R. Johnson, D. Pearson, K. Pingali
99 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
101 Optimal Code Motion: Theory and Practice
102 J. Knoop, O. Ruthing, B. Steffen
103 ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994
105 The power of assignment motion
106 J. Knoop, O. Ruthing, B. Steffen
107 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
109 Global code motion / global value numbering
111 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
113 Value Driven Redundancy Elimination
115 Rice University Ph.D. thesis, Apr. 1996
119 Massively Scalar Compiler Project, Rice University, Sep. 1996
121 High Performance Compilers for Parallel Computing
125 Advanced Compiler Design and Implementation
127 Morgan Kaufmann, 1997
129 Building an Optimizing Compiler
133 People wishing to speed up the code here should read:
134 Elimination Algorithms for Data Flow Analysis
135 B.G. Ryder, M.C. Paull
136 ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986
138 How to Analyze Large Programs Efficiently and Informatively
139 D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck
140 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
142 People wishing to do something different can find various possibilities
143 in the above papers and elsewhere.
148 #include "coretypes.h"
156 #include "hard-reg-set.h"
159 #include "insn-config.h"
161 #include "basic-block.h"
163 #include "function.h"
172 #include "tree-pass.h"
175 /* Propagate flow information through back edges and thus enable PRE's
176 moving loop invariant calculations out of loops.
178 Originally this tended to create worse overall code, but several
179 improvements during the development of PRE seem to have made following
180 back edges generally a win.
182 Note much of the loop invariant code motion done here would normally
183 be done by loop.c, which has more heuristics for when to move invariants
184 out of loops. At some point we might need to move some of those
185 heuristics into gcse.c. */
187 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
188 are a superset of those done by GCSE.
190 We perform the following steps:
192 1) Compute basic block information.
194 2) Compute table of places where registers are set.
196 3) Perform copy/constant propagation.
198 4) Perform global cse using lazy code motion if not optimizing
199 for size, or code hoisting if we are.
201 5) Perform another pass of copy/constant propagation.
203 Two passes of copy/constant propagation are done because the first one
204 enables more GCSE and the second one helps to clean up the copies that
205 GCSE creates. This is needed more for PRE than for Classic because Classic
206 GCSE will try to use an existing register containing the common
207 subexpression rather than create a new one. This is harder to do for PRE
208 because of the code motion (which Classic GCSE doesn't do).
210 Expressions we are interested in GCSE-ing are of the form
211 (set (pseudo-reg) (expression)).
212 Function want_to_gcse_p says what these are.
214 PRE handles moving invariant expressions out of loops (by treating them as
215 partially redundant).
217 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
218 assignment) based GVN (global value numbering). L. T. Simpson's paper
219 (Rice University) on value numbering is a useful reference for this.
221 **********************
223 We used to support multiple passes but there are diminishing returns in
224 doing so. The first pass usually makes 90% of the changes that are doable.
225 A second pass can make a few more changes made possible by the first pass.
226 Experiments show any further passes don't make enough changes to justify
229 A study of spec92 using an unlimited number of passes:
230 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
231 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
232 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
234 It was found doing copy propagation between each pass enables further
237 PRE is quite expensive in complicated functions because the DFA can take
238 a while to converge. Hence we only perform one pass. The parameter
239 max-gcse-passes can be modified if one wants to experiment.
241 **********************
243 The steps for PRE are:
245 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
247 2) Perform the data flow analysis for PRE.
249 3) Delete the redundant instructions
251 4) Insert the required copies [if any] that make the partially
252 redundant instructions fully redundant.
254 5) For other reaching expressions, insert an instruction to copy the value
255 to a newly created pseudo that will reach the redundant instruction.
257 The deletion is done first so that when we do insertions we
258 know which pseudo reg to use.
260 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
261 argue it is not. The number of iterations for the algorithm to converge
262 is typically 2-4 so I don't view it as that expensive (relatively speaking).
264 PRE GCSE depends heavily on the second CSE pass to clean up the copies
265 we create. To make an expression reach the place where it's redundant,
266 the result of the expression is copied to a new register, and the redundant
267 expression is deleted by replacing it with this new register. Classic GCSE
268 doesn't have this problem as much as it computes the reaching defs of
269 each register in each block and thus can try to use an existing
272 /* GCSE global vars. */
274 /* Note whether or not we should run jump optimization after gcse. We
275 want to do this for two cases.
277 * If we changed any jumps via cprop.
279 * If we added any labels via edge splitting. */
280 static int run_jump_opt_after_gcse;
282 /* An obstack for our working variables. */
283 static struct obstack gcse_obstack;
285 struct reg_use {rtx reg_rtx; };
287 /* Hash table of expressions. */
291 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
293 /* Index in the available expression bitmaps. */
295 /* Next entry with the same hash. */
296 struct expr *next_same_hash;
297 /* List of anticipatable occurrences in basic blocks in the function.
298 An "anticipatable occurrence" is one that is the first occurrence in the
299 basic block, the operands are not modified in the basic block prior
300 to the occurrence and the output is not used between the start of
301 the block and the occurrence. */
302 struct occr *antic_occr;
303 /* List of available occurrence in basic blocks in the function.
304 An "available occurrence" is one that is the last occurrence in the
305 basic block and the operands are not modified by following statements in
306 the basic block [including this insn]. */
307 struct occr *avail_occr;
308 /* Non-null if the computation is PRE redundant.
309 The value is the newly created pseudo-reg to record a copy of the
310 expression in all the places that reach the redundant copy. */
314 /* Occurrence of an expression.
315 There is one per basic block. If a pattern appears more than once the
316 last appearance is used [or first for anticipatable expressions]. */
320 /* Next occurrence of this expression. */
322 /* The insn that computes the expression. */
324 /* Nonzero if this [anticipatable] occurrence has been deleted. */
326 /* Nonzero if this [available] occurrence has been copied to
328 /* ??? This is mutually exclusive with deleted_p, so they could share
333 /* Expression and copy propagation hash tables.
334 Each hash table is an array of buckets.
335 ??? It is known that if it were an array of entries, structure elements
336 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
337 not clear whether in the final analysis a sufficient amount of memory would
338 be saved as the size of the available expression bitmaps would be larger
339 [one could build a mapping table without holes afterwards though].
340 Someday I'll perform the computation and figure it out. */
345 This is an array of `expr_hash_table_size' elements. */
348 /* Size of the hash table, in elements. */
351 /* Number of hash table elements. */
352 unsigned int n_elems;
354 /* Whether the table is expression of copy propagation one. */
358 /* Expression hash table. */
359 static struct hash_table expr_hash_table;
361 /* Copy propagation hash table. */
362 static struct hash_table set_hash_table;
364 /* Mapping of uids to cuids.
365 Only real insns get cuids. */
366 static int *uid_cuid;
368 /* Highest UID in UID_CUID. */
371 /* Get the cuid of an insn. */
372 #ifdef ENABLE_CHECKING
373 #define INSN_CUID(INSN) \
374 (gcc_assert (INSN_UID (INSN) <= max_uid), uid_cuid[INSN_UID (INSN)])
376 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
379 /* Number of cuids. */
382 /* Mapping of cuids to insns. */
383 static rtx *cuid_insn;
385 /* Get insn from cuid. */
386 #define CUID_INSN(CUID) (cuid_insn[CUID])
388 /* Maximum register number in function prior to doing gcse + 1.
389 Registers created during this pass have regno >= max_gcse_regno.
390 This is named with "gcse" to not collide with global of same name. */
391 static unsigned int max_gcse_regno;
393 /* Table of registers that are modified.
395 For each register, each element is a list of places where the pseudo-reg
398 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
399 requires knowledge of which blocks kill which regs [and thus could use
400 a bitmap instead of the lists `reg_set_table' uses].
402 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
403 num-regs) [however perhaps it may be useful to keep the data as is]. One
404 advantage of recording things this way is that `reg_set_table' is fairly
405 sparse with respect to pseudo regs but for hard regs could be fairly dense
406 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
407 up functions like compute_transp since in the case of pseudo-regs we only
408 need to iterate over the number of times a pseudo-reg is set, not over the
409 number of basic blocks [clearly there is a bit of a slow down in the cases
410 where a pseudo is set more than once in a block, however it is believed
411 that the net effect is to speed things up]. This isn't done for hard-regs
412 because recording call-clobbered hard-regs in `reg_set_table' at each
413 function call can consume a fair bit of memory, and iterating over
414 hard-regs stored this way in compute_transp will be more expensive. */
416 typedef struct reg_set
418 /* The next setting of this register. */
419 struct reg_set *next;
420 /* The index of the block where it was set. */
424 static reg_set **reg_set_table;
426 /* Size of `reg_set_table'.
427 The table starts out at max_gcse_regno + slop, and is enlarged as
429 static int reg_set_table_size;
431 /* Amount to grow `reg_set_table' by when it's full. */
432 #define REG_SET_TABLE_SLOP 100
434 /* This is a list of expressions which are MEMs and will be used by load
436 Load motion tracks MEMs which aren't killed by
437 anything except itself. (i.e., loads and stores to a single location).
438 We can then allow movement of these MEM refs with a little special
439 allowance. (all stores copy the same value to the reaching reg used
440 for the loads). This means all values used to store into memory must have
441 no side effects so we can re-issue the setter value.
442 Store Motion uses this structure as an expression table to track stores
443 which look interesting, and might be moveable towards the exit block. */
447 struct expr * expr; /* Gcse expression reference for LM. */
448 rtx pattern; /* Pattern of this mem. */
449 rtx pattern_regs; /* List of registers mentioned by the mem. */
450 rtx loads; /* INSN list of loads seen. */
451 rtx stores; /* INSN list of stores seen. */
452 struct ls_expr * next; /* Next in the list. */
453 int invalid; /* Invalid for some reason. */
454 int index; /* If it maps to a bitmap index. */
455 unsigned int hash_index; /* Index when in a hash table. */
456 rtx reaching_reg; /* Register to use when re-writing. */
459 /* Array of implicit set patterns indexed by basic block index. */
460 static rtx *implicit_sets;
462 /* Head of the list of load/store memory refs. */
463 static struct ls_expr * pre_ldst_mems = NULL;
465 /* Hashtable for the load/store memory refs. */
466 static htab_t pre_ldst_table = NULL;
468 /* Bitmap containing one bit for each register in the program.
469 Used when performing GCSE to track which registers have been set since
470 the start of the basic block. */
471 static regset reg_set_bitmap;
473 /* For each block, a bitmap of registers set in the block.
474 This is used by compute_transp.
475 It is computed during hash table computation and not by compute_sets
476 as it includes registers added since the last pass (or between cprop and
477 gcse) and it's currently not easy to realloc sbitmap vectors. */
478 static sbitmap *reg_set_in_block;
480 /* Array, indexed by basic block number for a list of insns which modify
481 memory within that block. */
482 static rtx * modify_mem_list;
483 static bitmap modify_mem_list_set;
485 /* This array parallels modify_mem_list, but is kept canonicalized. */
486 static rtx * canon_modify_mem_list;
488 /* Bitmap indexed by block numbers to record which blocks contain
490 static bitmap blocks_with_calls;
492 /* Various variables for statistics gathering. */
494 /* Memory used in a pass.
495 This isn't intended to be absolutely precise. Its intent is only
496 to keep an eye on memory usage. */
497 static int bytes_used;
499 /* GCSE substitutions made. */
500 static int gcse_subst_count;
501 /* Number of copy instructions created. */
502 static int gcse_create_count;
503 /* Number of local constants propagated. */
504 static int local_const_prop_count;
505 /* Number of local copies propagated. */
506 static int local_copy_prop_count;
507 /* Number of global constants propagated. */
508 static int global_const_prop_count;
509 /* Number of global copies propagated. */
510 static int global_copy_prop_count;
512 /* For available exprs */
513 static sbitmap *ae_kill, *ae_gen;
515 static void compute_can_copy (void);
516 static void *gmalloc (size_t) ATTRIBUTE_MALLOC;
517 static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC;
518 static void *grealloc (void *, size_t);
519 static void *gcse_alloc (unsigned long);
520 static void alloc_gcse_mem (void);
521 static void free_gcse_mem (void);
522 static void alloc_reg_set_mem (int);
523 static void free_reg_set_mem (void);
524 static void record_one_set (int, rtx);
525 static void record_set_info (rtx, rtx, void *);
526 static void compute_sets (void);
527 static void hash_scan_insn (rtx, struct hash_table *, int);
528 static void hash_scan_set (rtx, rtx, struct hash_table *);
529 static void hash_scan_clobber (rtx, rtx, struct hash_table *);
530 static void hash_scan_call (rtx, rtx, struct hash_table *);
531 static int want_to_gcse_p (rtx);
532 static bool can_assign_to_reg_p (rtx);
533 static bool gcse_constant_p (rtx);
534 static int oprs_unchanged_p (rtx, rtx, int);
535 static int oprs_anticipatable_p (rtx, rtx);
536 static int oprs_available_p (rtx, rtx);
537 static void insert_expr_in_table (rtx, enum machine_mode, rtx, int, int,
538 struct hash_table *);
539 static void insert_set_in_table (rtx, rtx, struct hash_table *);
540 static unsigned int hash_expr (rtx, enum machine_mode, int *, int);
541 static unsigned int hash_set (int, int);
542 static int expr_equiv_p (rtx, rtx);
543 static void record_last_reg_set_info (rtx, int);
544 static void record_last_mem_set_info (rtx);
545 static void record_last_set_info (rtx, rtx, void *);
546 static void compute_hash_table (struct hash_table *);
547 static void alloc_hash_table (int, struct hash_table *, int);
548 static void free_hash_table (struct hash_table *);
549 static void compute_hash_table_work (struct hash_table *);
550 static void dump_hash_table (FILE *, const char *, struct hash_table *);
551 static struct expr *lookup_set (unsigned int, struct hash_table *);
552 static struct expr *next_set (unsigned int, struct expr *);
553 static void reset_opr_set_tables (void);
554 static int oprs_not_set_p (rtx, rtx);
555 static void mark_call (rtx);
556 static void mark_set (rtx, rtx);
557 static void mark_clobber (rtx, rtx);
558 static void mark_oprs_set (rtx);
559 static void alloc_cprop_mem (int, int);
560 static void free_cprop_mem (void);
561 static void compute_transp (rtx, int, sbitmap *, int);
562 static void compute_transpout (void);
563 static void compute_local_properties (sbitmap *, sbitmap *, sbitmap *,
564 struct hash_table *);
565 static void compute_cprop_data (void);
566 static void find_used_regs (rtx *, void *);
567 static int try_replace_reg (rtx, rtx, rtx);
568 static struct expr *find_avail_set (int, rtx);
569 static int cprop_jump (basic_block, rtx, rtx, rtx, rtx);
570 static void mems_conflict_for_gcse_p (rtx, rtx, void *);
571 static int load_killed_in_block_p (basic_block, int, rtx, int);
572 static void canon_list_insert (rtx, rtx, void *);
573 static int cprop_insn (rtx, int);
574 static int cprop (int);
575 static void find_implicit_sets (void);
576 static int one_cprop_pass (int, bool, bool);
577 static bool constprop_register (rtx, rtx, rtx, bool);
578 static struct expr *find_bypass_set (int, int);
579 static bool reg_killed_on_edge (rtx, edge);
580 static int bypass_block (basic_block, rtx, rtx);
581 static int bypass_conditional_jumps (void);
582 static void alloc_pre_mem (int, int);
583 static void free_pre_mem (void);
584 static void compute_pre_data (void);
585 static int pre_expr_reaches_here_p (basic_block, struct expr *,
587 static void insert_insn_end_bb (struct expr *, basic_block, int);
588 static void pre_insert_copy_insn (struct expr *, rtx);
589 static void pre_insert_copies (void);
590 static int pre_delete (void);
591 static int pre_gcse (void);
592 static int one_pre_gcse_pass (int);
593 static void add_label_notes (rtx, rtx);
594 static void alloc_code_hoist_mem (int, int);
595 static void free_code_hoist_mem (void);
596 static void compute_code_hoist_vbeinout (void);
597 static void compute_code_hoist_data (void);
598 static int hoist_expr_reaches_here_p (basic_block, int, basic_block, char *);
599 static void hoist_code (void);
600 static int one_code_hoisting_pass (void);
601 static rtx process_insert_insn (struct expr *);
602 static int pre_edge_insert (struct edge_list *, struct expr **);
603 static int pre_expr_reaches_here_p_work (basic_block, struct expr *,
604 basic_block, char *);
605 static struct ls_expr * ldst_entry (rtx);
606 static void free_ldst_entry (struct ls_expr *);
607 static void free_ldst_mems (void);
608 static void print_ldst_list (FILE *);
609 static struct ls_expr * find_rtx_in_ldst (rtx);
610 static int enumerate_ldsts (void);
611 static inline struct ls_expr * first_ls_expr (void);
612 static inline struct ls_expr * next_ls_expr (struct ls_expr *);
613 static int simple_mem (rtx);
614 static void invalidate_any_buried_refs (rtx);
615 static void compute_ld_motion_mems (void);
616 static void trim_ld_motion_mems (void);
617 static void update_ld_motion_stores (struct expr *);
618 static void reg_set_info (rtx, rtx, void *);
619 static void reg_clear_last_set (rtx, rtx, void *);
620 static bool store_ops_ok (rtx, int *);
621 static rtx extract_mentioned_regs (rtx);
622 static rtx extract_mentioned_regs_helper (rtx, rtx);
623 static void find_moveable_store (rtx, int *, int *);
624 static int compute_store_table (void);
625 static bool load_kills_store (rtx, rtx, int);
626 static bool find_loads (rtx, rtx, int);
627 static bool store_killed_in_insn (rtx, rtx, rtx, int);
628 static bool store_killed_after (rtx, rtx, rtx, basic_block, int *, rtx *);
629 static bool store_killed_before (rtx, rtx, rtx, basic_block, int *);
630 static void build_store_vectors (void);
631 static void insert_insn_start_bb (rtx, basic_block);
632 static int insert_store (struct ls_expr *, edge);
633 static void remove_reachable_equiv_notes (basic_block, struct ls_expr *);
634 static void replace_store_insn (rtx, rtx, basic_block, struct ls_expr *);
635 static void delete_store (struct ls_expr *, basic_block);
636 static void free_store_memory (void);
637 static void store_motion (void);
638 static void free_insn_expr_list_list (rtx *);
639 static void clear_modify_mem_tables (void);
640 static void free_modify_mem_tables (void);
641 static rtx gcse_emit_move_after (rtx, rtx, rtx);
642 static void local_cprop_find_used_regs (rtx *, void *);
643 static bool do_local_cprop (rtx, rtx, bool, rtx*);
644 static bool adjust_libcall_notes (rtx, rtx, rtx, rtx*);
645 static void local_cprop_pass (bool);
646 static bool is_too_expensive (const char *);
649 /* Entry point for global common subexpression elimination.
650 F is the first instruction in the function. Return nonzero if a
654 gcse_main (rtx f ATTRIBUTE_UNUSED)
657 /* Bytes used at start of pass. */
658 int initial_bytes_used;
659 /* Maximum number of bytes used by a pass. */
661 /* Point to release obstack data from for each pass. */
662 char *gcse_obstack_bottom;
664 /* We do not construct an accurate cfg in functions which call
665 setjmp, so just punt to be safe. */
666 if (current_function_calls_setjmp)
669 /* Assume that we do not need to run jump optimizations after gcse. */
670 run_jump_opt_after_gcse = 0;
672 /* Identify the basic block information for this function, including
673 successors and predecessors. */
674 max_gcse_regno = max_reg_num ();
677 dump_flow_info (dump_file, dump_flags);
679 /* Return if there's nothing to do, or it is too expensive. */
680 if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1
681 || is_too_expensive (_("GCSE disabled")))
684 gcc_obstack_init (&gcse_obstack);
688 init_alias_analysis ();
689 /* Record where pseudo-registers are set. This data is kept accurate
690 during each pass. ??? We could also record hard-reg information here
691 [since it's unchanging], however it is currently done during hash table
694 It may be tempting to compute MEM set information here too, but MEM sets
695 will be subject to code motion one day and thus we need to compute
696 information about memory sets when we build the hash tables. */
698 alloc_reg_set_mem (max_gcse_regno);
702 initial_bytes_used = bytes_used;
704 gcse_obstack_bottom = gcse_alloc (1);
706 while (changed && pass < MAX_GCSE_PASSES)
710 fprintf (dump_file, "GCSE pass %d\n\n", pass + 1);
712 /* Initialize bytes_used to the space for the pred/succ lists,
713 and the reg_set_table data. */
714 bytes_used = initial_bytes_used;
716 /* Each pass may create new registers, so recalculate each time. */
717 max_gcse_regno = max_reg_num ();
721 /* Don't allow constant propagation to modify jumps
723 timevar_push (TV_CPROP1);
724 changed = one_cprop_pass (pass + 1, false, false);
725 timevar_pop (TV_CPROP1);
731 timevar_push (TV_PRE);
732 changed |= one_pre_gcse_pass (pass + 1);
733 /* We may have just created new basic blocks. Release and
734 recompute various things which are sized on the number of
738 free_modify_mem_tables ();
739 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
740 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
743 alloc_reg_set_mem (max_reg_num ());
745 run_jump_opt_after_gcse = 1;
746 timevar_pop (TV_PRE);
749 if (max_pass_bytes < bytes_used)
750 max_pass_bytes = bytes_used;
752 /* Free up memory, then reallocate for code hoisting. We can
753 not re-use the existing allocated memory because the tables
754 will not have info for the insns or registers created by
755 partial redundancy elimination. */
758 /* It does not make sense to run code hoisting unless we are optimizing
759 for code size -- it rarely makes programs faster, and can make
760 them bigger if we did partial redundancy elimination (when optimizing
761 for space, we don't run the partial redundancy algorithms). */
764 timevar_push (TV_HOIST);
765 max_gcse_regno = max_reg_num ();
767 changed |= one_code_hoisting_pass ();
770 if (max_pass_bytes < bytes_used)
771 max_pass_bytes = bytes_used;
772 timevar_pop (TV_HOIST);
777 fprintf (dump_file, "\n");
781 obstack_free (&gcse_obstack, gcse_obstack_bottom);
785 /* Do one last pass of copy propagation, including cprop into
786 conditional jumps. */
788 max_gcse_regno = max_reg_num ();
790 /* This time, go ahead and allow cprop to alter jumps. */
791 timevar_push (TV_CPROP2);
792 one_cprop_pass (pass + 1, true, false);
793 timevar_pop (TV_CPROP2);
798 fprintf (dump_file, "GCSE of %s: %d basic blocks, ",
799 current_function_name (), n_basic_blocks);
800 fprintf (dump_file, "%d pass%s, %d bytes\n\n",
801 pass, pass > 1 ? "es" : "", max_pass_bytes);
804 obstack_free (&gcse_obstack, NULL);
807 /* We are finished with alias. */
808 end_alias_analysis ();
809 allocate_reg_info (max_reg_num (), FALSE, FALSE);
811 if (!optimize_size && flag_gcse_sm)
813 timevar_push (TV_LSM);
815 timevar_pop (TV_LSM);
818 /* Record where pseudo-registers are set. */
819 return run_jump_opt_after_gcse;
822 /* Misc. utilities. */
824 /* Nonzero for each mode that supports (set (reg) (reg)).
825 This is trivially true for integer and floating point values.
826 It may or may not be true for condition codes. */
827 static char can_copy[(int) NUM_MACHINE_MODES];
829 /* Compute which modes support reg/reg copy operations. */
832 compute_can_copy (void)
835 #ifndef AVOID_CCMODE_COPIES
838 memset (can_copy, 0, NUM_MACHINE_MODES);
841 for (i = 0; i < NUM_MACHINE_MODES; i++)
842 if (GET_MODE_CLASS (i) == MODE_CC)
844 #ifdef AVOID_CCMODE_COPIES
847 reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1);
848 insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
849 if (recog (PATTERN (insn), insn, NULL) >= 0)
859 /* Returns whether the mode supports reg/reg copy operations. */
862 can_copy_p (enum machine_mode mode)
864 static bool can_copy_init_p = false;
866 if (! can_copy_init_p)
869 can_copy_init_p = true;
872 return can_copy[mode] != 0;
875 /* Cover function to xmalloc to record bytes allocated. */
878 gmalloc (size_t size)
881 return xmalloc (size);
884 /* Cover function to xcalloc to record bytes allocated. */
887 gcalloc (size_t nelem, size_t elsize)
889 bytes_used += nelem * elsize;
890 return xcalloc (nelem, elsize);
893 /* Cover function to xrealloc.
894 We don't record the additional size since we don't know it.
895 It won't affect memory usage stats much anyway. */
898 grealloc (void *ptr, size_t size)
900 return xrealloc (ptr, size);
903 /* Cover function to obstack_alloc. */
906 gcse_alloc (unsigned long size)
909 return obstack_alloc (&gcse_obstack, size);
912 /* Allocate memory for the cuid mapping array,
913 and reg/memory set tracking tables.
915 This is called at the start of each pass. */
918 alloc_gcse_mem (void)
924 /* Find the largest UID and create a mapping from UIDs to CUIDs.
925 CUIDs are like UIDs except they increase monotonically, have no gaps,
926 and only apply to real insns.
927 (Actually, there are gaps, for insn that are not inside a basic block.
928 but we should never see those anyway, so this is OK.) */
930 max_uid = get_max_uid ();
931 uid_cuid = gcalloc (max_uid + 1, sizeof (int));
934 FOR_BB_INSNS (bb, insn)
937 uid_cuid[INSN_UID (insn)] = i++;
939 uid_cuid[INSN_UID (insn)] = i;
942 /* Create a table mapping cuids to insns. */
945 cuid_insn = gcalloc (max_cuid + 1, sizeof (rtx));
948 FOR_BB_INSNS (bb, insn)
950 CUID_INSN (i++) = insn;
952 /* Allocate vars to track sets of regs. */
953 reg_set_bitmap = BITMAP_ALLOC (NULL);
955 /* Allocate vars to track sets of regs, memory per block. */
956 reg_set_in_block = sbitmap_vector_alloc (last_basic_block, max_gcse_regno);
957 /* Allocate array to keep a list of insns which modify memory in each
959 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
960 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
961 modify_mem_list_set = BITMAP_ALLOC (NULL);
962 blocks_with_calls = BITMAP_ALLOC (NULL);
965 /* Free memory allocated by alloc_gcse_mem. */
973 BITMAP_FREE (reg_set_bitmap);
975 sbitmap_vector_free (reg_set_in_block);
976 free_modify_mem_tables ();
977 BITMAP_FREE (modify_mem_list_set);
978 BITMAP_FREE (blocks_with_calls);
981 /* Compute the local properties of each recorded expression.
983 Local properties are those that are defined by the block, irrespective of
986 An expression is transparent in a block if its operands are not modified
989 An expression is computed (locally available) in a block if it is computed
990 at least once and expression would contain the same value if the
991 computation was moved to the end of the block.
993 An expression is locally anticipatable in a block if it is computed at
994 least once and expression would contain the same value if the computation
995 was moved to the beginning of the block.
997 We call this routine for cprop, pre and code hoisting. They all compute
998 basically the same information and thus can easily share this code.
1000 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1001 properties. If NULL, then it is not necessary to compute or record that
1002 particular property.
1004 TABLE controls which hash table to look at. If it is set hash table,
1005 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1009 compute_local_properties (sbitmap *transp, sbitmap *comp, sbitmap *antloc,
1010 struct hash_table *table)
1014 /* Initialize any bitmaps that were passed in. */
1018 sbitmap_vector_zero (transp, last_basic_block);
1020 sbitmap_vector_ones (transp, last_basic_block);
1024 sbitmap_vector_zero (comp, last_basic_block);
1026 sbitmap_vector_zero (antloc, last_basic_block);
1028 for (i = 0; i < table->size; i++)
1032 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
1034 int indx = expr->bitmap_index;
1037 /* The expression is transparent in this block if it is not killed.
1038 We start by assuming all are transparent [none are killed], and
1039 then reset the bits for those that are. */
1041 compute_transp (expr->expr, indx, transp, table->set_p);
1043 /* The occurrences recorded in antic_occr are exactly those that
1044 we want to set to nonzero in ANTLOC. */
1046 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
1048 SET_BIT (antloc[BLOCK_NUM (occr->insn)], indx);
1050 /* While we're scanning the table, this is a good place to
1052 occr->deleted_p = 0;
1055 /* The occurrences recorded in avail_occr are exactly those that
1056 we want to set to nonzero in COMP. */
1058 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
1060 SET_BIT (comp[BLOCK_NUM (occr->insn)], indx);
1062 /* While we're scanning the table, this is a good place to
1067 /* While we're scanning the table, this is a good place to
1069 expr->reaching_reg = 0;
1074 /* Register set information.
1076 `reg_set_table' records where each register is set or otherwise
1079 static struct obstack reg_set_obstack;
1082 alloc_reg_set_mem (int n_regs)
1084 reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
1085 reg_set_table = gcalloc (reg_set_table_size, sizeof (struct reg_set *));
1087 gcc_obstack_init (®_set_obstack);
1091 free_reg_set_mem (void)
1093 free (reg_set_table);
1094 obstack_free (®_set_obstack, NULL);
1097 /* Record REGNO in the reg_set table. */
1100 record_one_set (int regno, rtx insn)
1102 /* Allocate a new reg_set element and link it onto the list. */
1103 struct reg_set *new_reg_info;
1105 /* If the table isn't big enough, enlarge it. */
1106 if (regno >= reg_set_table_size)
1108 int new_size = regno + REG_SET_TABLE_SLOP;
1110 reg_set_table = grealloc (reg_set_table,
1111 new_size * sizeof (struct reg_set *));
1112 memset (reg_set_table + reg_set_table_size, 0,
1113 (new_size - reg_set_table_size) * sizeof (struct reg_set *));
1114 reg_set_table_size = new_size;
1117 new_reg_info = obstack_alloc (®_set_obstack, sizeof (struct reg_set));
1118 bytes_used += sizeof (struct reg_set);
1119 new_reg_info->bb_index = BLOCK_NUM (insn);
1120 new_reg_info->next = reg_set_table[regno];
1121 reg_set_table[regno] = new_reg_info;
1124 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1125 an insn. The DATA is really the instruction in which the SET is
1129 record_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
1131 rtx record_set_insn = (rtx) data;
1133 if (REG_P (dest) && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
1134 record_one_set (REGNO (dest), record_set_insn);
1137 /* Scan the function and record each set of each pseudo-register.
1139 This is called once, at the start of the gcse pass. See the comments for
1140 `reg_set_table' for further documentation. */
1149 FOR_BB_INSNS (bb, insn)
1151 note_stores (PATTERN (insn), record_set_info, insn);
1154 /* Hash table support. */
1156 struct reg_avail_info
1158 basic_block last_bb;
1163 static struct reg_avail_info *reg_avail_info;
1164 static basic_block current_bb;
1167 /* See whether X, the source of a set, is something we want to consider for
1171 want_to_gcse_p (rtx x)
1173 switch (GET_CODE (x))
1184 return can_assign_to_reg_p (x);
1188 /* Used internally by can_assign_to_reg_p. */
1190 static GTY(()) rtx test_insn;
1192 /* Return true if we can assign X to a pseudo register. */
1195 can_assign_to_reg_p (rtx x)
1197 int num_clobbers = 0;
1200 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1201 if (general_operand (x, GET_MODE (x)))
1203 else if (GET_MODE (x) == VOIDmode)
1206 /* Otherwise, check if we can make a valid insn from it. First initialize
1207 our test insn if we haven't already. */
1211 = make_insn_raw (gen_rtx_SET (VOIDmode,
1212 gen_rtx_REG (word_mode,
1213 FIRST_PSEUDO_REGISTER * 2),
1215 NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0;
1218 /* Now make an insn like the one we would make when GCSE'ing and see if
1220 PUT_MODE (SET_DEST (PATTERN (test_insn)), GET_MODE (x));
1221 SET_SRC (PATTERN (test_insn)) = x;
1222 return ((icode = recog (PATTERN (test_insn), test_insn, &num_clobbers)) >= 0
1223 && (num_clobbers == 0 || ! added_clobbers_hard_reg_p (icode)));
1226 /* Return nonzero if the operands of expression X are unchanged from the
1227 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1228 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1231 oprs_unchanged_p (rtx x, rtx insn, int avail_p)
1240 code = GET_CODE (x);
1245 struct reg_avail_info *info = ®_avail_info[REGNO (x)];
1247 if (info->last_bb != current_bb)
1250 return info->last_set < INSN_CUID (insn);
1252 return info->first_set >= INSN_CUID (insn);
1256 if (load_killed_in_block_p (current_bb, INSN_CUID (insn),
1260 return oprs_unchanged_p (XEXP (x, 0), insn, avail_p);
1286 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1290 /* If we are about to do the last recursive call needed at this
1291 level, change it into iteration. This function is called enough
1294 return oprs_unchanged_p (XEXP (x, i), insn, avail_p);
1296 else if (! oprs_unchanged_p (XEXP (x, i), insn, avail_p))
1299 else if (fmt[i] == 'E')
1300 for (j = 0; j < XVECLEN (x, i); j++)
1301 if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p))
1308 /* Used for communication between mems_conflict_for_gcse_p and
1309 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1310 conflict between two memory references. */
1311 static int gcse_mems_conflict_p;
1313 /* Used for communication between mems_conflict_for_gcse_p and
1314 load_killed_in_block_p. A memory reference for a load instruction,
1315 mems_conflict_for_gcse_p will see if a memory store conflicts with
1316 this memory load. */
1317 static rtx gcse_mem_operand;
1319 /* DEST is the output of an instruction. If it is a memory reference, and
1320 possibly conflicts with the load found in gcse_mem_operand, then set
1321 gcse_mems_conflict_p to a nonzero value. */
1324 mems_conflict_for_gcse_p (rtx dest, rtx setter ATTRIBUTE_UNUSED,
1325 void *data ATTRIBUTE_UNUSED)
1327 while (GET_CODE (dest) == SUBREG
1328 || GET_CODE (dest) == ZERO_EXTRACT
1329 || GET_CODE (dest) == STRICT_LOW_PART)
1330 dest = XEXP (dest, 0);
1332 /* If DEST is not a MEM, then it will not conflict with the load. Note
1333 that function calls are assumed to clobber memory, but are handled
1338 /* If we are setting a MEM in our list of specially recognized MEMs,
1339 don't mark as killed this time. */
1341 if (expr_equiv_p (dest, gcse_mem_operand) && pre_ldst_mems != NULL)
1343 if (!find_rtx_in_ldst (dest))
1344 gcse_mems_conflict_p = 1;
1348 if (true_dependence (dest, GET_MODE (dest), gcse_mem_operand,
1350 gcse_mems_conflict_p = 1;
1353 /* Return nonzero if the expression in X (a memory reference) is killed
1354 in block BB before or after the insn with the CUID in UID_LIMIT.
1355 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1358 To check the entire block, set UID_LIMIT to max_uid + 1 and
1362 load_killed_in_block_p (basic_block bb, int uid_limit, rtx x, int avail_p)
1364 rtx list_entry = modify_mem_list[bb->index];
1366 /* If this is a readonly then we aren't going to be changing it. */
1367 if (MEM_READONLY_P (x))
1373 /* Ignore entries in the list that do not apply. */
1375 && INSN_CUID (XEXP (list_entry, 0)) < uid_limit)
1377 && INSN_CUID (XEXP (list_entry, 0)) > uid_limit))
1379 list_entry = XEXP (list_entry, 1);
1383 setter = XEXP (list_entry, 0);
1385 /* If SETTER is a call everything is clobbered. Note that calls
1386 to pure functions are never put on the list, so we need not
1387 worry about them. */
1388 if (CALL_P (setter))
1391 /* SETTER must be an INSN of some kind that sets memory. Call
1392 note_stores to examine each hunk of memory that is modified.
1394 The note_stores interface is pretty limited, so we have to
1395 communicate via global variables. Yuk. */
1396 gcse_mem_operand = x;
1397 gcse_mems_conflict_p = 0;
1398 note_stores (PATTERN (setter), mems_conflict_for_gcse_p, NULL);
1399 if (gcse_mems_conflict_p)
1401 list_entry = XEXP (list_entry, 1);
1406 /* Return nonzero if the operands of expression X are unchanged from
1407 the start of INSN's basic block up to but not including INSN. */
1410 oprs_anticipatable_p (rtx x, rtx insn)
1412 return oprs_unchanged_p (x, insn, 0);
1415 /* Return nonzero if the operands of expression X are unchanged from
1416 INSN to the end of INSN's basic block. */
1419 oprs_available_p (rtx x, rtx insn)
1421 return oprs_unchanged_p (x, insn, 1);
1424 /* Hash expression X.
1426 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1427 indicating if a volatile operand is found or if the expression contains
1428 something we don't want to insert in the table. HASH_TABLE_SIZE is
1429 the current size of the hash table to be probed. */
1432 hash_expr (rtx x, enum machine_mode mode, int *do_not_record_p,
1433 int hash_table_size)
1437 *do_not_record_p = 0;
1439 hash = hash_rtx (x, mode, do_not_record_p,
1440 NULL, /*have_reg_qty=*/false);
1441 return hash % hash_table_size;
1444 /* Hash a set of register REGNO.
1446 Sets are hashed on the register that is set. This simplifies the PRE copy
1449 ??? May need to make things more elaborate. Later, as necessary. */
1452 hash_set (int regno, int hash_table_size)
1457 return hash % hash_table_size;
1460 /* Return nonzero if exp1 is equivalent to exp2. */
1463 expr_equiv_p (rtx x, rtx y)
1465 return exp_equiv_p (x, y, 0, true);
1468 /* Insert expression X in INSN in the hash TABLE.
1469 If it is already present, record it as the last occurrence in INSN's
1472 MODE is the mode of the value X is being stored into.
1473 It is only used if X is a CONST_INT.
1475 ANTIC_P is nonzero if X is an anticipatable expression.
1476 AVAIL_P is nonzero if X is an available expression. */
1479 insert_expr_in_table (rtx x, enum machine_mode mode, rtx insn, int antic_p,
1480 int avail_p, struct hash_table *table)
1482 int found, do_not_record_p;
1484 struct expr *cur_expr, *last_expr = NULL;
1485 struct occr *antic_occr, *avail_occr;
1487 hash = hash_expr (x, mode, &do_not_record_p, table->size);
1489 /* Do not insert expression in table if it contains volatile operands,
1490 or if hash_expr determines the expression is something we don't want
1491 to or can't handle. */
1492 if (do_not_record_p)
1495 cur_expr = table->table[hash];
1498 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
1500 /* If the expression isn't found, save a pointer to the end of
1502 last_expr = cur_expr;
1503 cur_expr = cur_expr->next_same_hash;
1508 cur_expr = gcse_alloc (sizeof (struct expr));
1509 bytes_used += sizeof (struct expr);
1510 if (table->table[hash] == NULL)
1511 /* This is the first pattern that hashed to this index. */
1512 table->table[hash] = cur_expr;
1514 /* Add EXPR to end of this hash chain. */
1515 last_expr->next_same_hash = cur_expr;
1517 /* Set the fields of the expr element. */
1519 cur_expr->bitmap_index = table->n_elems++;
1520 cur_expr->next_same_hash = NULL;
1521 cur_expr->antic_occr = NULL;
1522 cur_expr->avail_occr = NULL;
1525 /* Now record the occurrence(s). */
1528 antic_occr = cur_expr->antic_occr;
1530 if (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn))
1534 /* Found another instance of the expression in the same basic block.
1535 Prefer the currently recorded one. We want the first one in the
1536 block and the block is scanned from start to end. */
1537 ; /* nothing to do */
1540 /* First occurrence of this expression in this basic block. */
1541 antic_occr = gcse_alloc (sizeof (struct occr));
1542 bytes_used += sizeof (struct occr);
1543 antic_occr->insn = insn;
1544 antic_occr->next = cur_expr->antic_occr;
1545 antic_occr->deleted_p = 0;
1546 cur_expr->antic_occr = antic_occr;
1552 avail_occr = cur_expr->avail_occr;
1554 if (avail_occr && BLOCK_NUM (avail_occr->insn) == BLOCK_NUM (insn))
1556 /* Found another instance of the expression in the same basic block.
1557 Prefer this occurrence to the currently recorded one. We want
1558 the last one in the block and the block is scanned from start
1560 avail_occr->insn = insn;
1564 /* First occurrence of this expression in this basic block. */
1565 avail_occr = gcse_alloc (sizeof (struct occr));
1566 bytes_used += sizeof (struct occr);
1567 avail_occr->insn = insn;
1568 avail_occr->next = cur_expr->avail_occr;
1569 avail_occr->deleted_p = 0;
1570 cur_expr->avail_occr = avail_occr;
1575 /* Insert pattern X in INSN in the hash table.
1576 X is a SET of a reg to either another reg or a constant.
1577 If it is already present, record it as the last occurrence in INSN's
1581 insert_set_in_table (rtx x, rtx insn, struct hash_table *table)
1585 struct expr *cur_expr, *last_expr = NULL;
1586 struct occr *cur_occr;
1588 gcc_assert (GET_CODE (x) == SET && REG_P (SET_DEST (x)));
1590 hash = hash_set (REGNO (SET_DEST (x)), table->size);
1592 cur_expr = table->table[hash];
1595 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
1597 /* If the expression isn't found, save a pointer to the end of
1599 last_expr = cur_expr;
1600 cur_expr = cur_expr->next_same_hash;
1605 cur_expr = gcse_alloc (sizeof (struct expr));
1606 bytes_used += sizeof (struct expr);
1607 if (table->table[hash] == NULL)
1608 /* This is the first pattern that hashed to this index. */
1609 table->table[hash] = cur_expr;
1611 /* Add EXPR to end of this hash chain. */
1612 last_expr->next_same_hash = cur_expr;
1614 /* Set the fields of the expr element.
1615 We must copy X because it can be modified when copy propagation is
1616 performed on its operands. */
1617 cur_expr->expr = copy_rtx (x);
1618 cur_expr->bitmap_index = table->n_elems++;
1619 cur_expr->next_same_hash = NULL;
1620 cur_expr->antic_occr = NULL;
1621 cur_expr->avail_occr = NULL;
1624 /* Now record the occurrence. */
1625 cur_occr = cur_expr->avail_occr;
1627 if (cur_occr && BLOCK_NUM (cur_occr->insn) == BLOCK_NUM (insn))
1629 /* Found another instance of the expression in the same basic block.
1630 Prefer this occurrence to the currently recorded one. We want
1631 the last one in the block and the block is scanned from start
1633 cur_occr->insn = insn;
1637 /* First occurrence of this expression in this basic block. */
1638 cur_occr = gcse_alloc (sizeof (struct occr));
1639 bytes_used += sizeof (struct occr);
1641 cur_occr->insn = insn;
1642 cur_occr->next = cur_expr->avail_occr;
1643 cur_occr->deleted_p = 0;
1644 cur_expr->avail_occr = cur_occr;
1648 /* Determine whether the rtx X should be treated as a constant for
1649 the purposes of GCSE's constant propagation. */
1652 gcse_constant_p (rtx x)
1654 /* Consider a COMPARE of two integers constant. */
1655 if (GET_CODE (x) == COMPARE
1656 && GET_CODE (XEXP (x, 0)) == CONST_INT
1657 && GET_CODE (XEXP (x, 1)) == CONST_INT)
1660 /* Consider a COMPARE of the same registers is a constant
1661 if they are not floating point registers. */
1662 if (GET_CODE(x) == COMPARE
1663 && REG_P (XEXP (x, 0)) && REG_P (XEXP (x, 1))
1664 && REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 1))
1665 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 0)))
1666 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 1))))
1669 return CONSTANT_P (x);
1672 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
1676 hash_scan_set (rtx pat, rtx insn, struct hash_table *table)
1678 rtx src = SET_SRC (pat);
1679 rtx dest = SET_DEST (pat);
1682 if (GET_CODE (src) == CALL)
1683 hash_scan_call (src, insn, table);
1685 else if (REG_P (dest))
1687 unsigned int regno = REGNO (dest);
1690 /* See if a REG_NOTE shows this equivalent to a simpler expression.
1691 This allows us to do a single GCSE pass and still eliminate
1692 redundant constants, addresses or other expressions that are
1693 constructed with multiple instructions. */
1694 note = find_reg_equal_equiv_note (insn);
1697 ? gcse_constant_p (XEXP (note, 0))
1698 : want_to_gcse_p (XEXP (note, 0))))
1699 src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src);
1701 /* Only record sets of pseudo-regs in the hash table. */
1703 && regno >= FIRST_PSEUDO_REGISTER
1704 /* Don't GCSE something if we can't do a reg/reg copy. */
1705 && can_copy_p (GET_MODE (dest))
1706 /* GCSE commonly inserts instruction after the insn. We can't
1707 do that easily for EH_REGION notes so disable GCSE on these
1709 && !find_reg_note (insn, REG_EH_REGION, NULL_RTX)
1710 /* Is SET_SRC something we want to gcse? */
1711 && want_to_gcse_p (src)
1712 /* Don't CSE a nop. */
1713 && ! set_noop_p (pat)
1714 /* Don't GCSE if it has attached REG_EQUIV note.
1715 At this point this only function parameters should have
1716 REG_EQUIV notes and if the argument slot is used somewhere
1717 explicitly, it means address of parameter has been taken,
1718 so we should not extend the lifetime of the pseudo. */
1719 && (note == NULL_RTX || ! MEM_P (XEXP (note, 0))))
1721 /* An expression is not anticipatable if its operands are
1722 modified before this insn or if this is not the only SET in
1724 int antic_p = oprs_anticipatable_p (src, insn) && single_set (insn);
1725 /* An expression is not available if its operands are
1726 subsequently modified, including this insn. It's also not
1727 available if this is a branch, because we can't insert
1728 a set after the branch. */
1729 int avail_p = (oprs_available_p (src, insn)
1730 && ! JUMP_P (insn));
1732 insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p, table);
1735 /* Record sets for constant/copy propagation. */
1736 else if (table->set_p
1737 && regno >= FIRST_PSEUDO_REGISTER
1739 && REGNO (src) >= FIRST_PSEUDO_REGISTER
1740 && can_copy_p (GET_MODE (dest))
1741 && REGNO (src) != regno)
1742 || gcse_constant_p (src))
1743 /* A copy is not available if its src or dest is subsequently
1744 modified. Here we want to search from INSN+1 on, but
1745 oprs_available_p searches from INSN on. */
1746 && (insn == BB_END (BLOCK_FOR_INSN (insn))
1747 || ((tmp = next_nonnote_insn (insn)) != NULL_RTX
1748 && oprs_available_p (pat, tmp))))
1749 insert_set_in_table (pat, insn, table);
1751 /* In case of store we want to consider the memory value as available in
1752 the REG stored in that memory. This makes it possible to remove
1753 redundant loads from due to stores to the same location. */
1754 else if (flag_gcse_las && REG_P (src) && MEM_P (dest))
1756 unsigned int regno = REGNO (src);
1758 /* Do not do this for constant/copy propagation. */
1760 /* Only record sets of pseudo-regs in the hash table. */
1761 && regno >= FIRST_PSEUDO_REGISTER
1762 /* Don't GCSE something if we can't do a reg/reg copy. */
1763 && can_copy_p (GET_MODE (src))
1764 /* GCSE commonly inserts instruction after the insn. We can't
1765 do that easily for EH_REGION notes so disable GCSE on these
1767 && ! find_reg_note (insn, REG_EH_REGION, NULL_RTX)
1768 /* Is SET_DEST something we want to gcse? */
1769 && want_to_gcse_p (dest)
1770 /* Don't CSE a nop. */
1771 && ! set_noop_p (pat)
1772 /* Don't GCSE if it has attached REG_EQUIV note.
1773 At this point this only function parameters should have
1774 REG_EQUIV notes and if the argument slot is used somewhere
1775 explicitly, it means address of parameter has been taken,
1776 so we should not extend the lifetime of the pseudo. */
1777 && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
1778 || ! MEM_P (XEXP (note, 0))))
1780 /* Stores are never anticipatable. */
1782 /* An expression is not available if its operands are
1783 subsequently modified, including this insn. It's also not
1784 available if this is a branch, because we can't insert
1785 a set after the branch. */
1786 int avail_p = oprs_available_p (dest, insn)
1789 /* Record the memory expression (DEST) in the hash table. */
1790 insert_expr_in_table (dest, GET_MODE (dest), insn,
1791 antic_p, avail_p, table);
1797 hash_scan_clobber (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
1798 struct hash_table *table ATTRIBUTE_UNUSED)
1800 /* Currently nothing to do. */
1804 hash_scan_call (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
1805 struct hash_table *table ATTRIBUTE_UNUSED)
1807 /* Currently nothing to do. */
1810 /* Process INSN and add hash table entries as appropriate.
1812 Only available expressions that set a single pseudo-reg are recorded.
1814 Single sets in a PARALLEL could be handled, but it's an extra complication
1815 that isn't dealt with right now. The trick is handling the CLOBBERs that
1816 are also in the PARALLEL. Later.
1818 If SET_P is nonzero, this is for the assignment hash table,
1819 otherwise it is for the expression hash table.
1820 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
1821 not record any expressions. */
1824 hash_scan_insn (rtx insn, struct hash_table *table, int in_libcall_block)
1826 rtx pat = PATTERN (insn);
1829 if (in_libcall_block)
1832 /* Pick out the sets of INSN and for other forms of instructions record
1833 what's been modified. */
1835 if (GET_CODE (pat) == SET)
1836 hash_scan_set (pat, insn, table);
1837 else if (GET_CODE (pat) == PARALLEL)
1838 for (i = 0; i < XVECLEN (pat, 0); i++)
1840 rtx x = XVECEXP (pat, 0, i);
1842 if (GET_CODE (x) == SET)
1843 hash_scan_set (x, insn, table);
1844 else if (GET_CODE (x) == CLOBBER)
1845 hash_scan_clobber (x, insn, table);
1846 else if (GET_CODE (x) == CALL)
1847 hash_scan_call (x, insn, table);
1850 else if (GET_CODE (pat) == CLOBBER)
1851 hash_scan_clobber (pat, insn, table);
1852 else if (GET_CODE (pat) == CALL)
1853 hash_scan_call (pat, insn, table);
1857 dump_hash_table (FILE *file, const char *name, struct hash_table *table)
1860 /* Flattened out table, so it's printed in proper order. */
1861 struct expr **flat_table;
1862 unsigned int *hash_val;
1865 flat_table = xcalloc (table->n_elems, sizeof (struct expr *));
1866 hash_val = xmalloc (table->n_elems * sizeof (unsigned int));
1868 for (i = 0; i < (int) table->size; i++)
1869 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
1871 flat_table[expr->bitmap_index] = expr;
1872 hash_val[expr->bitmap_index] = i;
1875 fprintf (file, "%s hash table (%d buckets, %d entries)\n",
1876 name, table->size, table->n_elems);
1878 for (i = 0; i < (int) table->n_elems; i++)
1879 if (flat_table[i] != 0)
1881 expr = flat_table[i];
1882 fprintf (file, "Index %d (hash value %d)\n ",
1883 expr->bitmap_index, hash_val[i]);
1884 print_rtl (file, expr->expr);
1885 fprintf (file, "\n");
1888 fprintf (file, "\n");
1894 /* Record register first/last/block set information for REGNO in INSN.
1896 first_set records the first place in the block where the register
1897 is set and is used to compute "anticipatability".
1899 last_set records the last place in the block where the register
1900 is set and is used to compute "availability".
1902 last_bb records the block for which first_set and last_set are
1903 valid, as a quick test to invalidate them.
1905 reg_set_in_block records whether the register is set in the block
1906 and is used to compute "transparency". */
1909 record_last_reg_set_info (rtx insn, int regno)
1911 struct reg_avail_info *info = ®_avail_info[regno];
1912 int cuid = INSN_CUID (insn);
1914 info->last_set = cuid;
1915 if (info->last_bb != current_bb)
1917 info->last_bb = current_bb;
1918 info->first_set = cuid;
1919 SET_BIT (reg_set_in_block[current_bb->index], regno);
1924 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
1925 Note we store a pair of elements in the list, so they have to be
1926 taken off pairwise. */
1929 canon_list_insert (rtx dest ATTRIBUTE_UNUSED, rtx unused1 ATTRIBUTE_UNUSED,
1932 rtx dest_addr, insn;
1935 while (GET_CODE (dest) == SUBREG
1936 || GET_CODE (dest) == ZERO_EXTRACT
1937 || GET_CODE (dest) == STRICT_LOW_PART)
1938 dest = XEXP (dest, 0);
1940 /* If DEST is not a MEM, then it will not conflict with a load. Note
1941 that function calls are assumed to clobber memory, but are handled
1947 dest_addr = get_addr (XEXP (dest, 0));
1948 dest_addr = canon_rtx (dest_addr);
1949 insn = (rtx) v_insn;
1950 bb = BLOCK_NUM (insn);
1952 canon_modify_mem_list[bb] =
1953 alloc_EXPR_LIST (VOIDmode, dest_addr, canon_modify_mem_list[bb]);
1954 canon_modify_mem_list[bb] =
1955 alloc_EXPR_LIST (VOIDmode, dest, canon_modify_mem_list[bb]);
1958 /* Record memory modification information for INSN. We do not actually care
1959 about the memory location(s) that are set, or even how they are set (consider
1960 a CALL_INSN). We merely need to record which insns modify memory. */
1963 record_last_mem_set_info (rtx insn)
1965 int bb = BLOCK_NUM (insn);
1967 /* load_killed_in_block_p will handle the case of calls clobbering
1969 modify_mem_list[bb] = alloc_INSN_LIST (insn, modify_mem_list[bb]);
1970 bitmap_set_bit (modify_mem_list_set, bb);
1974 /* Note that traversals of this loop (other than for free-ing)
1975 will break after encountering a CALL_INSN. So, there's no
1976 need to insert a pair of items, as canon_list_insert does. */
1977 canon_modify_mem_list[bb] =
1978 alloc_INSN_LIST (insn, canon_modify_mem_list[bb]);
1979 bitmap_set_bit (blocks_with_calls, bb);
1982 note_stores (PATTERN (insn), canon_list_insert, (void*) insn);
1985 /* Called from compute_hash_table via note_stores to handle one
1986 SET or CLOBBER in an insn. DATA is really the instruction in which
1987 the SET is taking place. */
1990 record_last_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
1992 rtx last_set_insn = (rtx) data;
1994 if (GET_CODE (dest) == SUBREG)
1995 dest = SUBREG_REG (dest);
1998 record_last_reg_set_info (last_set_insn, REGNO (dest));
1999 else if (MEM_P (dest)
2000 /* Ignore pushes, they clobber nothing. */
2001 && ! push_operand (dest, GET_MODE (dest)))
2002 record_last_mem_set_info (last_set_insn);
2005 /* Top level function to create an expression or assignment hash table.
2007 Expression entries are placed in the hash table if
2008 - they are of the form (set (pseudo-reg) src),
2009 - src is something we want to perform GCSE on,
2010 - none of the operands are subsequently modified in the block
2012 Assignment entries are placed in the hash table if
2013 - they are of the form (set (pseudo-reg) src),
2014 - src is something we want to perform const/copy propagation on,
2015 - none of the operands or target are subsequently modified in the block
2017 Currently src must be a pseudo-reg or a const_int.
2019 TABLE is the table computed. */
2022 compute_hash_table_work (struct hash_table *table)
2026 /* While we compute the hash table we also compute a bit array of which
2027 registers are set in which blocks.
2028 ??? This isn't needed during const/copy propagation, but it's cheap to
2030 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
2032 /* re-Cache any INSN_LIST nodes we have allocated. */
2033 clear_modify_mem_tables ();
2034 /* Some working arrays used to track first and last set in each block. */
2035 reg_avail_info = gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
2037 for (i = 0; i < max_gcse_regno; ++i)
2038 reg_avail_info[i].last_bb = NULL;
2040 FOR_EACH_BB (current_bb)
2044 int in_libcall_block;
2046 /* First pass over the instructions records information used to
2047 determine when registers and memory are first and last set.
2048 ??? hard-reg reg_set_in_block computation
2049 could be moved to compute_sets since they currently don't change. */
2051 FOR_BB_INSNS (current_bb, insn)
2053 if (! INSN_P (insn))
2058 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2059 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2060 record_last_reg_set_info (insn, regno);
2065 note_stores (PATTERN (insn), record_last_set_info, insn);
2068 /* Insert implicit sets in the hash table. */
2070 && implicit_sets[current_bb->index] != NULL_RTX)
2071 hash_scan_set (implicit_sets[current_bb->index],
2072 BB_HEAD (current_bb), table);
2074 /* The next pass builds the hash table. */
2075 in_libcall_block = 0;
2076 FOR_BB_INSNS (current_bb, insn)
2079 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2080 in_libcall_block = 1;
2081 else if (table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2082 in_libcall_block = 0;
2083 hash_scan_insn (insn, table, in_libcall_block);
2084 if (!table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2085 in_libcall_block = 0;
2089 free (reg_avail_info);
2090 reg_avail_info = NULL;
2093 /* Allocate space for the set/expr hash TABLE.
2094 N_INSNS is the number of instructions in the function.
2095 It is used to determine the number of buckets to use.
2096 SET_P determines whether set or expression table will
2100 alloc_hash_table (int n_insns, struct hash_table *table, int set_p)
2104 table->size = n_insns / 4;
2105 if (table->size < 11)
2108 /* Attempt to maintain efficient use of hash table.
2109 Making it an odd number is simplest for now.
2110 ??? Later take some measurements. */
2112 n = table->size * sizeof (struct expr *);
2113 table->table = gmalloc (n);
2114 table->set_p = set_p;
2117 /* Free things allocated by alloc_hash_table. */
2120 free_hash_table (struct hash_table *table)
2122 free (table->table);
2125 /* Compute the hash TABLE for doing copy/const propagation or
2126 expression hash table. */
2129 compute_hash_table (struct hash_table *table)
2131 /* Initialize count of number of entries in hash table. */
2133 memset (table->table, 0, table->size * sizeof (struct expr *));
2135 compute_hash_table_work (table);
2138 /* Expression tracking support. */
2140 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2141 table entry, or NULL if not found. */
2143 static struct expr *
2144 lookup_set (unsigned int regno, struct hash_table *table)
2146 unsigned int hash = hash_set (regno, table->size);
2149 expr = table->table[hash];
2151 while (expr && REGNO (SET_DEST (expr->expr)) != regno)
2152 expr = expr->next_same_hash;
2157 /* Return the next entry for REGNO in list EXPR. */
2159 static struct expr *
2160 next_set (unsigned int regno, struct expr *expr)
2163 expr = expr->next_same_hash;
2164 while (expr && REGNO (SET_DEST (expr->expr)) != regno);
2169 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2170 types may be mixed. */
2173 free_insn_expr_list_list (rtx *listp)
2177 for (list = *listp; list ; list = next)
2179 next = XEXP (list, 1);
2180 if (GET_CODE (list) == EXPR_LIST)
2181 free_EXPR_LIST_node (list);
2183 free_INSN_LIST_node (list);
2189 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2191 clear_modify_mem_tables (void)
2196 EXECUTE_IF_SET_IN_BITMAP (modify_mem_list_set, 0, i, bi)
2198 free_INSN_LIST_list (modify_mem_list + i);
2199 free_insn_expr_list_list (canon_modify_mem_list + i);
2201 bitmap_clear (modify_mem_list_set);
2202 bitmap_clear (blocks_with_calls);
2205 /* Release memory used by modify_mem_list_set. */
2208 free_modify_mem_tables (void)
2210 clear_modify_mem_tables ();
2211 free (modify_mem_list);
2212 free (canon_modify_mem_list);
2213 modify_mem_list = 0;
2214 canon_modify_mem_list = 0;
2217 /* Reset tables used to keep track of what's still available [since the
2218 start of the block]. */
2221 reset_opr_set_tables (void)
2223 /* Maintain a bitmap of which regs have been set since beginning of
2225 CLEAR_REG_SET (reg_set_bitmap);
2227 /* Also keep a record of the last instruction to modify memory.
2228 For now this is very trivial, we only record whether any memory
2229 location has been modified. */
2230 clear_modify_mem_tables ();
2233 /* Return nonzero if the operands of X are not set before INSN in
2234 INSN's basic block. */
2237 oprs_not_set_p (rtx x, rtx insn)
2246 code = GET_CODE (x);
2262 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn),
2263 INSN_CUID (insn), x, 0))
2266 return oprs_not_set_p (XEXP (x, 0), insn);
2269 return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x));
2275 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2279 /* If we are about to do the last recursive call
2280 needed at this level, change it into iteration.
2281 This function is called enough to be worth it. */
2283 return oprs_not_set_p (XEXP (x, i), insn);
2285 if (! oprs_not_set_p (XEXP (x, i), insn))
2288 else if (fmt[i] == 'E')
2289 for (j = 0; j < XVECLEN (x, i); j++)
2290 if (! oprs_not_set_p (XVECEXP (x, i, j), insn))
2297 /* Mark things set by a CALL. */
2300 mark_call (rtx insn)
2302 if (! CONST_OR_PURE_CALL_P (insn))
2303 record_last_mem_set_info (insn);
2306 /* Mark things set by a SET. */
2309 mark_set (rtx pat, rtx insn)
2311 rtx dest = SET_DEST (pat);
2313 while (GET_CODE (dest) == SUBREG
2314 || GET_CODE (dest) == ZERO_EXTRACT
2315 || GET_CODE (dest) == STRICT_LOW_PART)
2316 dest = XEXP (dest, 0);
2319 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (dest));
2320 else if (MEM_P (dest))
2321 record_last_mem_set_info (insn);
2323 if (GET_CODE (SET_SRC (pat)) == CALL)
2327 /* Record things set by a CLOBBER. */
2330 mark_clobber (rtx pat, rtx insn)
2332 rtx clob = XEXP (pat, 0);
2334 while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART)
2335 clob = XEXP (clob, 0);
2338 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (clob));
2340 record_last_mem_set_info (insn);
2343 /* Record things set by INSN.
2344 This data is used by oprs_not_set_p. */
2347 mark_oprs_set (rtx insn)
2349 rtx pat = PATTERN (insn);
2352 if (GET_CODE (pat) == SET)
2353 mark_set (pat, insn);
2354 else if (GET_CODE (pat) == PARALLEL)
2355 for (i = 0; i < XVECLEN (pat, 0); i++)
2357 rtx x = XVECEXP (pat, 0, i);
2359 if (GET_CODE (x) == SET)
2361 else if (GET_CODE (x) == CLOBBER)
2362 mark_clobber (x, insn);
2363 else if (GET_CODE (x) == CALL)
2367 else if (GET_CODE (pat) == CLOBBER)
2368 mark_clobber (pat, insn);
2369 else if (GET_CODE (pat) == CALL)
2374 /* Compute copy/constant propagation working variables. */
2376 /* Local properties of assignments. */
2377 static sbitmap *cprop_pavloc;
2378 static sbitmap *cprop_absaltered;
2380 /* Global properties of assignments (computed from the local properties). */
2381 static sbitmap *cprop_avin;
2382 static sbitmap *cprop_avout;
2384 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
2385 basic blocks. N_SETS is the number of sets. */
2388 alloc_cprop_mem (int n_blocks, int n_sets)
2390 cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
2391 cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
2393 cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
2394 cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
2397 /* Free vars used by copy/const propagation. */
2400 free_cprop_mem (void)
2402 sbitmap_vector_free (cprop_pavloc);
2403 sbitmap_vector_free (cprop_absaltered);
2404 sbitmap_vector_free (cprop_avin);
2405 sbitmap_vector_free (cprop_avout);
2408 /* For each block, compute whether X is transparent. X is either an
2409 expression or an assignment [though we don't care which, for this context
2410 an assignment is treated as an expression]. For each block where an
2411 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
2415 compute_transp (rtx x, int indx, sbitmap *bmap, int set_p)
2423 /* repeat is used to turn tail-recursion into iteration since GCC
2424 can't do it when there's no return value. */
2430 code = GET_CODE (x);
2436 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
2439 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
2440 SET_BIT (bmap[bb->index], indx);
2444 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
2445 SET_BIT (bmap[r->bb_index], indx);
2450 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
2453 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
2454 RESET_BIT (bmap[bb->index], indx);
2458 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
2459 RESET_BIT (bmap[r->bb_index], indx);
2466 if (! MEM_READONLY_P (x))
2471 /* First handle all the blocks with calls. We don't need to
2472 do any list walking for them. */
2473 EXECUTE_IF_SET_IN_BITMAP (blocks_with_calls, 0, bb_index, bi)
2476 SET_BIT (bmap[bb_index], indx);
2478 RESET_BIT (bmap[bb_index], indx);
2481 /* Now iterate over the blocks which have memory modifications
2482 but which do not have any calls. */
2483 EXECUTE_IF_AND_COMPL_IN_BITMAP (modify_mem_list_set,
2487 rtx list_entry = canon_modify_mem_list[bb_index];
2491 rtx dest, dest_addr;
2493 /* LIST_ENTRY must be an INSN of some kind that sets memory.
2494 Examine each hunk of memory that is modified. */
2496 dest = XEXP (list_entry, 0);
2497 list_entry = XEXP (list_entry, 1);
2498 dest_addr = XEXP (list_entry, 0);
2500 if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
2501 x, rtx_addr_varies_p))
2504 SET_BIT (bmap[bb_index], indx);
2506 RESET_BIT (bmap[bb_index], indx);
2509 list_entry = XEXP (list_entry, 1);
2533 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2537 /* If we are about to do the last recursive call
2538 needed at this level, change it into iteration.
2539 This function is called enough to be worth it. */
2546 compute_transp (XEXP (x, i), indx, bmap, set_p);
2548 else if (fmt[i] == 'E')
2549 for (j = 0; j < XVECLEN (x, i); j++)
2550 compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
2554 /* Top level routine to do the dataflow analysis needed by copy/const
2558 compute_cprop_data (void)
2560 compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, &set_hash_table);
2561 compute_available (cprop_pavloc, cprop_absaltered,
2562 cprop_avout, cprop_avin);
2565 /* Copy/constant propagation. */
2567 /* Maximum number of register uses in an insn that we handle. */
2570 /* Table of uses found in an insn.
2571 Allocated statically to avoid alloc/free complexity and overhead. */
2572 static struct reg_use reg_use_table[MAX_USES];
2574 /* Index into `reg_use_table' while building it. */
2575 static int reg_use_count;
2577 /* Set up a list of register numbers used in INSN. The found uses are stored
2578 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
2579 and contains the number of uses in the table upon exit.
2581 ??? If a register appears multiple times we will record it multiple times.
2582 This doesn't hurt anything but it will slow things down. */
2585 find_used_regs (rtx *xptr, void *data ATTRIBUTE_UNUSED)
2592 /* repeat is used to turn tail-recursion into iteration since GCC
2593 can't do it when there's no return value. */
2598 code = GET_CODE (x);
2601 if (reg_use_count == MAX_USES)
2604 reg_use_table[reg_use_count].reg_rtx = x;
2608 /* Recursively scan the operands of this expression. */
2610 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2614 /* If we are about to do the last recursive call
2615 needed at this level, change it into iteration.
2616 This function is called enough to be worth it. */
2623 find_used_regs (&XEXP (x, i), data);
2625 else if (fmt[i] == 'E')
2626 for (j = 0; j < XVECLEN (x, i); j++)
2627 find_used_regs (&XVECEXP (x, i, j), data);
2631 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
2632 Returns nonzero is successful. */
2635 try_replace_reg (rtx from, rtx to, rtx insn)
2637 rtx note = find_reg_equal_equiv_note (insn);
2640 rtx set = single_set (insn);
2642 validate_replace_src_group (from, to, insn);
2643 if (num_changes_pending () && apply_change_group ())
2646 /* Try to simplify SET_SRC if we have substituted a constant. */
2647 if (success && set && CONSTANT_P (to))
2649 src = simplify_rtx (SET_SRC (set));
2652 validate_change (insn, &SET_SRC (set), src, 0);
2655 /* If there is already a NOTE, update the expression in it with our
2658 XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to);
2660 if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
2662 /* If above failed and this is a single set, try to simplify the source of
2663 the set given our substitution. We could perhaps try this for multiple
2664 SETs, but it probably won't buy us anything. */
2665 src = simplify_replace_rtx (SET_SRC (set), from, to);
2667 if (!rtx_equal_p (src, SET_SRC (set))
2668 && validate_change (insn, &SET_SRC (set), src, 0))
2671 /* If we've failed to do replacement, have a single SET, don't already
2672 have a note, and have no special SET, add a REG_EQUAL note to not
2673 lose information. */
2674 if (!success && note == 0 && set != 0
2675 && GET_CODE (SET_DEST (set)) != ZERO_EXTRACT
2676 && GET_CODE (SET_DEST (set)) != STRICT_LOW_PART)
2677 note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
2680 /* REG_EQUAL may get simplified into register.
2681 We don't allow that. Remove that note. This code ought
2682 not to happen, because previous code ought to synthesize
2683 reg-reg move, but be on the safe side. */
2684 if (note && REG_P (XEXP (note, 0)))
2685 remove_note (insn, note);
2690 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
2691 NULL no such set is found. */
2693 static struct expr *
2694 find_avail_set (int regno, rtx insn)
2696 /* SET1 contains the last set found that can be returned to the caller for
2697 use in a substitution. */
2698 struct expr *set1 = 0;
2700 /* Loops are not possible here. To get a loop we would need two sets
2701 available at the start of the block containing INSN. i.e. we would
2702 need two sets like this available at the start of the block:
2704 (set (reg X) (reg Y))
2705 (set (reg Y) (reg X))
2707 This can not happen since the set of (reg Y) would have killed the
2708 set of (reg X) making it unavailable at the start of this block. */
2712 struct expr *set = lookup_set (regno, &set_hash_table);
2714 /* Find a set that is available at the start of the block
2715 which contains INSN. */
2718 if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
2720 set = next_set (regno, set);
2723 /* If no available set was found we've reached the end of the
2724 (possibly empty) copy chain. */
2728 gcc_assert (GET_CODE (set->expr) == SET);
2730 src = SET_SRC (set->expr);
2732 /* We know the set is available.
2733 Now check that SRC is ANTLOC (i.e. none of the source operands
2734 have changed since the start of the block).
2736 If the source operand changed, we may still use it for the next
2737 iteration of this loop, but we may not use it for substitutions. */
2739 if (gcse_constant_p (src) || oprs_not_set_p (src, insn))
2742 /* If the source of the set is anything except a register, then
2743 we have reached the end of the copy chain. */
2747 /* Follow the copy chain, i.e. start another iteration of the loop
2748 and see if we have an available copy into SRC. */
2749 regno = REGNO (src);
2752 /* SET1 holds the last set that was available and anticipatable at
2757 /* Subroutine of cprop_insn that tries to propagate constants into
2758 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
2759 it is the instruction that immediately precedes JUMP, and must be a
2760 single SET of a register. FROM is what we will try to replace,
2761 SRC is the constant we will try to substitute for it. Returns nonzero
2762 if a change was made. */
2765 cprop_jump (basic_block bb, rtx setcc, rtx jump, rtx from, rtx src)
2767 rtx new, set_src, note_src;
2768 rtx set = pc_set (jump);
2769 rtx note = find_reg_equal_equiv_note (jump);
2773 note_src = XEXP (note, 0);
2774 if (GET_CODE (note_src) == EXPR_LIST)
2775 note_src = NULL_RTX;
2777 else note_src = NULL_RTX;
2779 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
2780 set_src = note_src ? note_src : SET_SRC (set);
2782 /* First substitute the SETCC condition into the JUMP instruction,
2783 then substitute that given values into this expanded JUMP. */
2784 if (setcc != NULL_RTX
2785 && !modified_between_p (from, setcc, jump)
2786 && !modified_between_p (src, setcc, jump))
2789 rtx setcc_set = single_set (setcc);
2790 rtx setcc_note = find_reg_equal_equiv_note (setcc);
2791 setcc_src = (setcc_note && GET_CODE (XEXP (setcc_note, 0)) != EXPR_LIST)
2792 ? XEXP (setcc_note, 0) : SET_SRC (setcc_set);
2793 set_src = simplify_replace_rtx (set_src, SET_DEST (setcc_set),
2799 new = simplify_replace_rtx (set_src, from, src);
2801 /* If no simplification can be made, then try the next register. */
2802 if (rtx_equal_p (new, SET_SRC (set)))
2805 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
2810 /* Ensure the value computed inside the jump insn to be equivalent
2811 to one computed by setcc. */
2812 if (setcc && modified_in_p (new, setcc))
2814 if (! validate_change (jump, &SET_SRC (set), new, 0))
2816 /* When (some) constants are not valid in a comparison, and there
2817 are two registers to be replaced by constants before the entire
2818 comparison can be folded into a constant, we need to keep
2819 intermediate information in REG_EQUAL notes. For targets with
2820 separate compare insns, such notes are added by try_replace_reg.
2821 When we have a combined compare-and-branch instruction, however,
2822 we need to attach a note to the branch itself to make this
2823 optimization work. */
2825 if (!rtx_equal_p (new, note_src))
2826 set_unique_reg_note (jump, REG_EQUAL, copy_rtx (new));
2830 /* Remove REG_EQUAL note after simplification. */
2832 remove_note (jump, note);
2834 /* If this has turned into an unconditional jump,
2835 then put a barrier after it so that the unreachable
2836 code will be deleted. */
2837 if (GET_CODE (SET_SRC (set)) == LABEL_REF)
2838 emit_barrier_after (jump);
2842 /* Delete the cc0 setter. */
2843 if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
2844 delete_insn (setcc);
2847 run_jump_opt_after_gcse = 1;
2849 global_const_prop_count++;
2850 if (dump_file != NULL)
2853 "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
2854 REGNO (from), INSN_UID (jump));
2855 print_rtl (dump_file, src);
2856 fprintf (dump_file, "\n");
2858 purge_dead_edges (bb);
2864 constprop_register (rtx insn, rtx from, rtx to, bool alter_jumps)
2868 /* Check for reg or cc0 setting instructions followed by
2869 conditional branch instructions first. */
2871 && (sset = single_set (insn)) != NULL
2873 && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
2875 rtx dest = SET_DEST (sset);
2876 if ((REG_P (dest) || CC0_P (dest))
2877 && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to))
2881 /* Handle normal insns next. */
2882 if (NONJUMP_INSN_P (insn)
2883 && try_replace_reg (from, to, insn))
2886 /* Try to propagate a CONST_INT into a conditional jump.
2887 We're pretty specific about what we will handle in this
2888 code, we can extend this as necessary over time.
2890 Right now the insn in question must look like
2891 (set (pc) (if_then_else ...)) */
2892 else if (alter_jumps && any_condjump_p (insn) && onlyjump_p (insn))
2893 return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to);
2897 /* Perform constant and copy propagation on INSN.
2898 The result is nonzero if a change was made. */
2901 cprop_insn (rtx insn, int alter_jumps)
2903 struct reg_use *reg_used;
2911 note_uses (&PATTERN (insn), find_used_regs, NULL);
2913 note = find_reg_equal_equiv_note (insn);
2915 /* We may win even when propagating constants into notes. */
2917 find_used_regs (&XEXP (note, 0), NULL);
2919 for (reg_used = ®_use_table[0]; reg_use_count > 0;
2920 reg_used++, reg_use_count--)
2922 unsigned int regno = REGNO (reg_used->reg_rtx);
2926 /* Ignore registers created by GCSE.
2927 We do this because ... */
2928 if (regno >= max_gcse_regno)
2931 /* If the register has already been set in this block, there's
2932 nothing we can do. */
2933 if (! oprs_not_set_p (reg_used->reg_rtx, insn))
2936 /* Find an assignment that sets reg_used and is available
2937 at the start of the block. */
2938 set = find_avail_set (regno, insn);
2943 /* ??? We might be able to handle PARALLELs. Later. */
2944 gcc_assert (GET_CODE (pat) == SET);
2946 src = SET_SRC (pat);
2948 /* Constant propagation. */
2949 if (gcse_constant_p (src))
2951 if (constprop_register (insn, reg_used->reg_rtx, src, alter_jumps))
2954 global_const_prop_count++;
2955 if (dump_file != NULL)
2957 fprintf (dump_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
2958 fprintf (dump_file, "insn %d with constant ", INSN_UID (insn));
2959 print_rtl (dump_file, src);
2960 fprintf (dump_file, "\n");
2962 if (INSN_DELETED_P (insn))
2966 else if (REG_P (src)
2967 && REGNO (src) >= FIRST_PSEUDO_REGISTER
2968 && REGNO (src) != regno)
2970 if (try_replace_reg (reg_used->reg_rtx, src, insn))
2973 global_copy_prop_count++;
2974 if (dump_file != NULL)
2976 fprintf (dump_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
2977 regno, INSN_UID (insn));
2978 fprintf (dump_file, " with reg %d\n", REGNO (src));
2981 /* The original insn setting reg_used may or may not now be
2982 deletable. We leave the deletion to flow. */
2983 /* FIXME: If it turns out that the insn isn't deletable,
2984 then we may have unnecessarily extended register lifetimes
2985 and made things worse. */
2993 /* Like find_used_regs, but avoid recording uses that appear in
2994 input-output contexts such as zero_extract or pre_dec. This
2995 restricts the cases we consider to those for which local cprop
2996 can legitimately make replacements. */
2999 local_cprop_find_used_regs (rtx *xptr, void *data)
3006 switch (GET_CODE (x))
3010 case STRICT_LOW_PART:
3019 /* Can only legitimately appear this early in the context of
3020 stack pushes for function arguments, but handle all of the
3021 codes nonetheless. */
3025 /* Setting a subreg of a register larger than word_mode leaves
3026 the non-written words unchanged. */
3027 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
3035 find_used_regs (xptr, data);
3038 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3039 their REG_EQUAL notes need updating. */
3042 do_local_cprop (rtx x, rtx insn, bool alter_jumps, rtx *libcall_sp)
3044 rtx newreg = NULL, newcnst = NULL;
3046 /* Rule out USE instructions and ASM statements as we don't want to
3047 change the hard registers mentioned. */
3049 && (REGNO (x) >= FIRST_PSEUDO_REGISTER
3050 || (GET_CODE (PATTERN (insn)) != USE
3051 && asm_noperands (PATTERN (insn)) < 0)))
3053 cselib_val *val = cselib_lookup (x, GET_MODE (x), 0);
3054 struct elt_loc_list *l;
3058 for (l = val->locs; l; l = l->next)
3060 rtx this_rtx = l->loc;
3063 /* Don't CSE non-constant values out of libcall blocks. */
3064 if (l->in_libcall && ! CONSTANT_P (this_rtx))
3067 if (gcse_constant_p (this_rtx))
3069 if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
3070 /* Don't copy propagate if it has attached REG_EQUIV note.
3071 At this point this only function parameters should have
3072 REG_EQUIV notes and if the argument slot is used somewhere
3073 explicitly, it means address of parameter has been taken,
3074 so we should not extend the lifetime of the pseudo. */
3075 && (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX))
3076 || ! MEM_P (XEXP (note, 0))))
3079 if (newcnst && constprop_register (insn, x, newcnst, alter_jumps))
3081 /* If we find a case where we can't fix the retval REG_EQUAL notes
3082 match the new register, we either have to abandon this replacement
3083 or fix delete_trivially_dead_insns to preserve the setting insn,
3084 or make it delete the REG_EUAQL note, and fix up all passes that
3085 require the REG_EQUAL note there. */
3088 adjusted = adjust_libcall_notes (x, newcnst, insn, libcall_sp);
3089 gcc_assert (adjusted);
3091 if (dump_file != NULL)
3093 fprintf (dump_file, "LOCAL CONST-PROP: Replacing reg %d in ",
3095 fprintf (dump_file, "insn %d with constant ",
3097 print_rtl (dump_file, newcnst);
3098 fprintf (dump_file, "\n");
3100 local_const_prop_count++;
3103 else if (newreg && newreg != x && try_replace_reg (x, newreg, insn))
3105 adjust_libcall_notes (x, newreg, insn, libcall_sp);
3106 if (dump_file != NULL)
3109 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
3110 REGNO (x), INSN_UID (insn));
3111 fprintf (dump_file, " with reg %d\n", REGNO (newreg));
3113 local_copy_prop_count++;
3120 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3121 their REG_EQUAL notes need updating to reflect that OLDREG has been
3122 replaced with NEWVAL in INSN. Return true if all substitutions could
3125 adjust_libcall_notes (rtx oldreg, rtx newval, rtx insn, rtx *libcall_sp)
3129 while ((end = *libcall_sp++))
3131 rtx note = find_reg_equal_equiv_note (end);
3138 if (reg_set_between_p (newval, PREV_INSN (insn), end))
3142 note = find_reg_equal_equiv_note (end);
3145 if (reg_mentioned_p (newval, XEXP (note, 0)))
3148 while ((end = *libcall_sp++));
3152 XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), oldreg, newval);
3158 #define MAX_NESTED_LIBCALLS 9
3160 /* Do local const/copy propagation (i.e. within each basic block).
3161 If ALTER_JUMPS is true, allow propagating into jump insns, which
3162 could modify the CFG. */
3165 local_cprop_pass (bool alter_jumps)
3169 struct reg_use *reg_used;
3170 rtx libcall_stack[MAX_NESTED_LIBCALLS + 1], *libcall_sp;
3171 bool changed = false;
3173 cselib_init (false);
3174 libcall_sp = &libcall_stack[MAX_NESTED_LIBCALLS];
3178 FOR_BB_INSNS (bb, insn)
3182 rtx note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
3186 gcc_assert (libcall_sp != libcall_stack);
3187 *--libcall_sp = XEXP (note, 0);
3189 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
3192 note = find_reg_equal_equiv_note (insn);
3196 note_uses (&PATTERN (insn), local_cprop_find_used_regs,
3199 local_cprop_find_used_regs (&XEXP (note, 0), NULL);
3201 for (reg_used = ®_use_table[0]; reg_use_count > 0;
3202 reg_used++, reg_use_count--)
3203 if (do_local_cprop (reg_used->reg_rtx, insn, alter_jumps,
3209 if (INSN_DELETED_P (insn))
3212 while (reg_use_count);
3214 cselib_process_insn (insn);
3217 /* Forget everything at the end of a basic block. Make sure we are
3218 not inside a libcall, they should never cross basic blocks. */
3219 cselib_clear_table ();
3220 gcc_assert (libcall_sp == &libcall_stack[MAX_NESTED_LIBCALLS]);
3225 /* Global analysis may get into infinite loops for unreachable blocks. */
3226 if (changed && alter_jumps)
3228 delete_unreachable_blocks ();
3229 free_reg_set_mem ();
3230 alloc_reg_set_mem (max_reg_num ());
3235 /* Forward propagate copies. This includes copies and constants. Return
3236 nonzero if a change was made. */
3239 cprop (int alter_jumps)
3245 /* Note we start at block 1. */
3246 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
3248 if (dump_file != NULL)
3249 fprintf (dump_file, "\n");
3254 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
3256 /* Reset tables used to keep track of what's still valid [since the
3257 start of the block]. */
3258 reset_opr_set_tables ();
3260 FOR_BB_INSNS (bb, insn)
3263 changed |= cprop_insn (insn, alter_jumps);
3265 /* Keep track of everything modified by this insn. */
3266 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
3267 call mark_oprs_set if we turned the insn into a NOTE. */
3268 if (! NOTE_P (insn))
3269 mark_oprs_set (insn);
3273 if (dump_file != NULL)
3274 fprintf (dump_file, "\n");
3279 /* Similar to get_condition, only the resulting condition must be
3280 valid at JUMP, instead of at EARLIEST.
3282 This differs from noce_get_condition in ifcvt.c in that we prefer not to
3283 settle for the condition variable in the jump instruction being integral.
3284 We prefer to be able to record the value of a user variable, rather than
3285 the value of a temporary used in a condition. This could be solved by
3286 recording the value of *every* register scanned by canonicalize_condition,
3287 but this would require some code reorganization. */
3290 fis_get_condition (rtx jump)
3292 return get_condition (jump, NULL, false, true);
3295 /* Check the comparison COND to see if we can safely form an implicit set from
3296 it. COND is either an EQ or NE comparison. */
3299 implicit_set_cond_p (rtx cond)
3301 enum machine_mode mode = GET_MODE (XEXP (cond, 0));
3302 rtx cst = XEXP (cond, 1);
3304 /* We can't perform this optimization if either operand might be or might
3305 contain a signed zero. */
3306 if (HONOR_SIGNED_ZEROS (mode))
3308 /* It is sufficient to check if CST is or contains a zero. We must
3309 handle float, complex, and vector. If any subpart is a zero, then
3310 the optimization can't be performed. */
3311 /* ??? The complex and vector checks are not implemented yet. We just
3312 always return zero for them. */
3313 if (GET_CODE (cst) == CONST_DOUBLE)
3316 REAL_VALUE_FROM_CONST_DOUBLE (d, cst);
3317 if (REAL_VALUES_EQUAL (d, dconst0))
3324 return gcse_constant_p (cst);
3327 /* Find the implicit sets of a function. An "implicit set" is a constraint
3328 on the value of a variable, implied by a conditional jump. For example,
3329 following "if (x == 2)", the then branch may be optimized as though the
3330 conditional performed an "explicit set", in this example, "x = 2". This
3331 function records the set patterns that are implicit at the start of each
3335 find_implicit_sets (void)
3337 basic_block bb, dest;
3343 /* Check for more than one successor. */
3344 if (EDGE_COUNT (bb->succs) > 1)
3346 cond = fis_get_condition (BB_END (bb));
3349 && (GET_CODE (cond) == EQ || GET_CODE (cond) == NE)
3350 && REG_P (XEXP (cond, 0))
3351 && REGNO (XEXP (cond, 0)) >= FIRST_PSEUDO_REGISTER
3352 && implicit_set_cond_p (cond))
3354 dest = GET_CODE (cond) == EQ ? BRANCH_EDGE (bb)->dest
3355 : FALLTHRU_EDGE (bb)->dest;
3357 if (dest && single_pred_p (dest)
3358 && dest != EXIT_BLOCK_PTR)
3360 new = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
3362 implicit_sets[dest->index] = new;
3365 fprintf(dump_file, "Implicit set of reg %d in ",
3366 REGNO (XEXP (cond, 0)));
3367 fprintf(dump_file, "basic block %d\n", dest->index);
3375 fprintf (dump_file, "Found %d implicit sets\n", count);
3378 /* Perform one copy/constant propagation pass.
3379 PASS is the pass count. If CPROP_JUMPS is true, perform constant
3380 propagation into conditional jumps. If BYPASS_JUMPS is true,
3381 perform conditional jump bypassing optimizations. */
3384 one_cprop_pass (int pass, bool cprop_jumps, bool bypass_jumps)
3388 global_const_prop_count = local_const_prop_count = 0;
3389 global_copy_prop_count = local_copy_prop_count = 0;
3391 local_cprop_pass (cprop_jumps);
3393 /* Determine implicit sets. */
3394 implicit_sets = XCNEWVEC (rtx, last_basic_block);
3395 find_implicit_sets ();
3397 alloc_hash_table (max_cuid, &set_hash_table, 1);
3398 compute_hash_table (&set_hash_table);
3400 /* Free implicit_sets before peak usage. */
3401 free (implicit_sets);
3402 implicit_sets = NULL;
3405 dump_hash_table (dump_file, "SET", &set_hash_table);
3406 if (set_hash_table.n_elems > 0)
3408 alloc_cprop_mem (last_basic_block, set_hash_table.n_elems);
3409 compute_cprop_data ();
3410 changed = cprop (cprop_jumps);
3412 changed |= bypass_conditional_jumps ();
3416 free_hash_table (&set_hash_table);
3420 fprintf (dump_file, "CPROP of %s, pass %d: %d bytes needed, ",
3421 current_function_name (), pass, bytes_used);
3422 fprintf (dump_file, "%d local const props, %d local copy props, ",
3423 local_const_prop_count, local_copy_prop_count);
3424 fprintf (dump_file, "%d global const props, %d global copy props\n\n",
3425 global_const_prop_count, global_copy_prop_count);
3427 /* Global analysis may get into infinite loops for unreachable blocks. */
3428 if (changed && cprop_jumps)
3429 delete_unreachable_blocks ();
3434 /* Bypass conditional jumps. */
3436 /* The value of last_basic_block at the beginning of the jump_bypass
3437 pass. The use of redirect_edge_and_branch_force may introduce new
3438 basic blocks, but the data flow analysis is only valid for basic
3439 block indices less than bypass_last_basic_block. */
3441 static int bypass_last_basic_block;
3443 /* Find a set of REGNO to a constant that is available at the end of basic
3444 block BB. Returns NULL if no such set is found. Based heavily upon
3447 static struct expr *
3448 find_bypass_set (int regno, int bb)
3450 struct expr *result = 0;
3455 struct expr *set = lookup_set (regno, &set_hash_table);
3459 if (TEST_BIT (cprop_avout[bb], set->bitmap_index))
3461 set = next_set (regno, set);
3467 gcc_assert (GET_CODE (set->expr) == SET);
3469 src = SET_SRC (set->expr);
3470 if (gcse_constant_p (src))
3476 regno = REGNO (src);
3482 /* Subroutine of bypass_block that checks whether a pseudo is killed by
3483 any of the instructions inserted on an edge. Jump bypassing places
3484 condition code setters on CFG edges using insert_insn_on_edge. This
3485 function is required to check that our data flow analysis is still
3486 valid prior to commit_edge_insertions. */
3489 reg_killed_on_edge (rtx reg, edge e)
3493 for (insn = e->insns.r; insn; insn = NEXT_INSN (insn))
3494 if (INSN_P (insn) && reg_set_p (reg, insn))
3500 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
3501 basic block BB which has more than one predecessor. If not NULL, SETCC
3502 is the first instruction of BB, which is immediately followed by JUMP_INSN
3503 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
3504 Returns nonzero if a change was made.
3506 During the jump bypassing pass, we may place copies of SETCC instructions
3507 on CFG edges. The following routine must be careful to pay attention to
3508 these inserted insns when performing its transformations. */
3511 bypass_block (basic_block bb, rtx setcc, rtx jump)
3516 int may_be_loop_header;
3520 insn = (setcc != NULL) ? setcc : jump;
3522 /* Determine set of register uses in INSN. */
3524 note_uses (&PATTERN (insn), find_used_regs, NULL);
3525 note = find_reg_equal_equiv_note (insn);
3527 find_used_regs (&XEXP (note, 0), NULL);
3529 may_be_loop_header = false;
3530 FOR_EACH_EDGE (e, ei, bb->preds)
3531 if (e->flags & EDGE_DFS_BACK)
3533 may_be_loop_header = true;
3538 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
3542 if (e->flags & EDGE_COMPLEX)
3548 /* We can't redirect edges from new basic blocks. */
3549 if (e->src->index >= bypass_last_basic_block)
3555 /* The irreducible loops created by redirecting of edges entering the
3556 loop from outside would decrease effectiveness of some of the following
3557 optimizations, so prevent this. */
3558 if (may_be_loop_header
3559 && !(e->flags & EDGE_DFS_BACK))
3565 for (i = 0; i < reg_use_count; i++)
3567 struct reg_use *reg_used = ®_use_table[i];
3568 unsigned int regno = REGNO (reg_used->reg_rtx);
3569 basic_block dest, old_dest;
3573 if (regno >= max_gcse_regno)
3576 set = find_bypass_set (regno, e->src->index);
3581 /* Check the data flow is valid after edge insertions. */
3582 if (e->insns.r && reg_killed_on_edge (reg_used->reg_rtx, e))
3585 src = SET_SRC (pc_set (jump));
3588 src = simplify_replace_rtx (src,
3589 SET_DEST (PATTERN (setcc)),
3590 SET_SRC (PATTERN (setcc)));
3592 new = simplify_replace_rtx (src, reg_used->reg_rtx,
3593 SET_SRC (set->expr));
3595 /* Jump bypassing may have already placed instructions on
3596 edges of the CFG. We can't bypass an outgoing edge that
3597 has instructions associated with it, as these insns won't
3598 get executed if the incoming edge is redirected. */
3602 edest = FALLTHRU_EDGE (bb);
3603 dest = edest->insns.r ? NULL : edest->dest;
3605 else if (GET_CODE (new) == LABEL_REF)
3607 dest = BLOCK_FOR_INSN (XEXP (new, 0));
3608 /* Don't bypass edges containing instructions. */
3609 edest = find_edge (bb, dest);
3610 if (edest && edest->insns.r)
3616 /* Avoid unification of the edge with other edges from original
3617 branch. We would end up emitting the instruction on "both"
3620 if (dest && setcc && !CC0_P (SET_DEST (PATTERN (setcc)))
3621 && find_edge (e->src, dest))
3627 && dest != EXIT_BLOCK_PTR)
3629 redirect_edge_and_branch_force (e, dest);
3631 /* Copy the register setter to the redirected edge.
3632 Don't copy CC0 setters, as CC0 is dead after jump. */
3635 rtx pat = PATTERN (setcc);
3636 if (!CC0_P (SET_DEST (pat)))
3637 insert_insn_on_edge (copy_insn (pat), e);
3640 if (dump_file != NULL)
3642 fprintf (dump_file, "JUMP-BYPASS: Proved reg %d "
3643 "in jump_insn %d equals constant ",
3644 regno, INSN_UID (jump));
3645 print_rtl (dump_file, SET_SRC (set->expr));
3646 fprintf (dump_file, "\nBypass edge from %d->%d to %d\n",
3647 e->src->index, old_dest->index, dest->index);
3660 /* Find basic blocks with more than one predecessor that only contain a
3661 single conditional jump. If the result of the comparison is known at
3662 compile-time from any incoming edge, redirect that edge to the
3663 appropriate target. Returns nonzero if a change was made.
3665 This function is now mis-named, because we also handle indirect jumps. */
3668 bypass_conditional_jumps (void)
3676 /* Note we start at block 1. */
3677 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
3680 bypass_last_basic_block = last_basic_block;
3681 mark_dfs_back_edges ();
3684 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb,
3685 EXIT_BLOCK_PTR, next_bb)
3687 /* Check for more than one predecessor. */
3688 if (!single_pred_p (bb))
3691 FOR_BB_INSNS (bb, insn)
3692 if (NONJUMP_INSN_P (insn))
3696 if (GET_CODE (PATTERN (insn)) != SET)
3699 dest = SET_DEST (PATTERN (insn));
3700 if (REG_P (dest) || CC0_P (dest))
3705 else if (JUMP_P (insn))
3707 if ((any_condjump_p (insn) || computed_jump_p (insn))
3708 && onlyjump_p (insn))
3709 changed |= bypass_block (bb, setcc, insn);
3712 else if (INSN_P (insn))
3717 /* If we bypassed any register setting insns, we inserted a
3718 copy on the redirected edge. These need to be committed. */
3720 commit_edge_insertions();
3725 /* Compute PRE+LCM working variables. */
3727 /* Local properties of expressions. */
3728 /* Nonzero for expressions that are transparent in the block. */
3729 static sbitmap *transp;
3731 /* Nonzero for expressions that are transparent at the end of the block.
3732 This is only zero for expressions killed by abnormal critical edge
3733 created by a calls. */
3734 static sbitmap *transpout;
3736 /* Nonzero for expressions that are computed (available) in the block. */
3737 static sbitmap *comp;
3739 /* Nonzero for expressions that are locally anticipatable in the block. */
3740 static sbitmap *antloc;
3742 /* Nonzero for expressions where this block is an optimal computation
3744 static sbitmap *pre_optimal;
3746 /* Nonzero for expressions which are redundant in a particular block. */
3747 static sbitmap *pre_redundant;
3749 /* Nonzero for expressions which should be inserted on a specific edge. */
3750 static sbitmap *pre_insert_map;
3752 /* Nonzero for expressions which should be deleted in a specific block. */
3753 static sbitmap *pre_delete_map;
3755 /* Contains the edge_list returned by pre_edge_lcm. */
3756 static struct edge_list *edge_list;
3758 /* Redundant insns. */
3759 static sbitmap pre_redundant_insns;
3761 /* Allocate vars used for PRE analysis. */
3764 alloc_pre_mem (int n_blocks, int n_exprs)
3766 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
3767 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
3768 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
3771 pre_redundant = NULL;
3772 pre_insert_map = NULL;
3773 pre_delete_map = NULL;
3774 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
3776 /* pre_insert and pre_delete are allocated later. */
3779 /* Free vars used for PRE analysis. */
3784 sbitmap_vector_free (transp);
3785 sbitmap_vector_free (comp);
3787 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
3790 sbitmap_vector_free (pre_optimal);
3792 sbitmap_vector_free (pre_redundant);
3794 sbitmap_vector_free (pre_insert_map);
3796 sbitmap_vector_free (pre_delete_map);
3798 transp = comp = NULL;
3799 pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
3802 /* Top level routine to do the dataflow analysis needed by PRE. */
3805 compute_pre_data (void)
3807 sbitmap trapping_expr;
3811 compute_local_properties (transp, comp, antloc, &expr_hash_table);
3812 sbitmap_vector_zero (ae_kill, last_basic_block);
3814 /* Collect expressions which might trap. */
3815 trapping_expr = sbitmap_alloc (expr_hash_table.n_elems);
3816 sbitmap_zero (trapping_expr);
3817 for (ui = 0; ui < expr_hash_table.size; ui++)
3820 for (e = expr_hash_table.table[ui]; e != NULL; e = e->next_same_hash)
3821 if (may_trap_p (e->expr))
3822 SET_BIT (trapping_expr, e->bitmap_index);
3825 /* Compute ae_kill for each basic block using:
3835 /* If the current block is the destination of an abnormal edge, we
3836 kill all trapping expressions because we won't be able to properly
3837 place the instruction on the edge. So make them neither
3838 anticipatable nor transparent. This is fairly conservative. */
3839 FOR_EACH_EDGE (e, ei, bb->preds)
3840 if (e->flags & EDGE_ABNORMAL)
3842 sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr);
3843 sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr);
3847 sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]);
3848 sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]);
3851 edge_list = pre_edge_lcm (expr_hash_table.n_elems, transp, comp, antloc,
3852 ae_kill, &pre_insert_map, &pre_delete_map);
3853 sbitmap_vector_free (antloc);
3855 sbitmap_vector_free (ae_kill);
3857 sbitmap_free (trapping_expr);
3862 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
3865 VISITED is a pointer to a working buffer for tracking which BB's have
3866 been visited. It is NULL for the top-level call.
3868 We treat reaching expressions that go through blocks containing the same
3869 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3870 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3871 2 as not reaching. The intent is to improve the probability of finding
3872 only one reaching expression and to reduce register lifetimes by picking
3873 the closest such expression. */
3876 pre_expr_reaches_here_p_work (basic_block occr_bb, struct expr *expr, basic_block bb, char *visited)
3881 FOR_EACH_EDGE (pred, ei, bb->preds)
3883 basic_block pred_bb = pred->src;
3885 if (pred->src == ENTRY_BLOCK_PTR
3886 /* Has predecessor has already been visited? */
3887 || visited[pred_bb->index])
3888 ;/* Nothing to do. */
3890 /* Does this predecessor generate this expression? */
3891 else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
3893 /* Is this the occurrence we're looking for?
3894 Note that there's only one generating occurrence per block
3895 so we just need to check the block number. */
3896 if (occr_bb == pred_bb)
3899 visited[pred_bb->index] = 1;
3901 /* Ignore this predecessor if it kills the expression. */
3902 else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
3903 visited[pred_bb->index] = 1;
3905 /* Neither gen nor kill. */
3908 visited[pred_bb->index] = 1;
3909 if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
3914 /* All paths have been checked. */
3918 /* The wrapper for pre_expr_reaches_here_work that ensures that any
3919 memory allocated for that function is returned. */
3922 pre_expr_reaches_here_p (basic_block occr_bb, struct expr *expr, basic_block bb)
3925 char *visited = XCNEWVEC (char, last_basic_block);
3927 rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited);
3934 /* Given an expr, generate RTL which we can insert at the end of a BB,
3935 or on an edge. Set the block number of any insns generated to
3939 process_insert_insn (struct expr *expr)
3941 rtx reg = expr->reaching_reg;
3942 rtx exp = copy_rtx (expr->expr);
3947 /* If the expression is something that's an operand, like a constant,
3948 just copy it to a register. */
3949 if (general_operand (exp, GET_MODE (reg)))
3950 emit_move_insn (reg, exp);
3952 /* Otherwise, make a new insn to compute this expression and make sure the
3953 insn will be recognized (this also adds any needed CLOBBERs). Copy the
3954 expression to make sure we don't have any sharing issues. */
3957 rtx insn = emit_insn (gen_rtx_SET (VOIDmode, reg, exp));
3959 if (insn_invalid_p (insn))
3970 /* Add EXPR to the end of basic block BB.
3972 This is used by both the PRE and code hoisting.
3974 For PRE, we want to verify that the expr is either transparent
3975 or locally anticipatable in the target block. This check makes
3976 no sense for code hoisting. */
3979 insert_insn_end_bb (struct expr *expr, basic_block bb, int pre)
3981 rtx insn = BB_END (bb);
3983 rtx reg = expr->reaching_reg;
3984 int regno = REGNO (reg);
3987 pat = process_insert_insn (expr);
3988 gcc_assert (pat && INSN_P (pat));
3991 while (NEXT_INSN (pat_end) != NULL_RTX)
3992 pat_end = NEXT_INSN (pat_end);
3994 /* If the last insn is a jump, insert EXPR in front [taking care to
3995 handle cc0, etc. properly]. Similarly we need to care trapping
3996 instructions in presence of non-call exceptions. */
3999 || (NONJUMP_INSN_P (insn)
4000 && (!single_succ_p (bb)
4001 || single_succ_edge (bb)->flags & EDGE_ABNORMAL)))
4006 /* It should always be the case that we can put these instructions
4007 anywhere in the basic block with performing PRE optimizations.
4009 gcc_assert (!NONJUMP_INSN_P (insn) || !pre
4010 || TEST_BIT (antloc[bb->index], expr->bitmap_index)
4011 || TEST_BIT (transp[bb->index], expr->bitmap_index));
4013 /* If this is a jump table, then we can't insert stuff here. Since
4014 we know the previous real insn must be the tablejump, we insert
4015 the new instruction just before the tablejump. */
4016 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
4017 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
4018 insn = prev_real_insn (insn);
4021 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4022 if cc0 isn't set. */
4023 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
4025 insn = XEXP (note, 0);
4028 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
4029 if (maybe_cc0_setter
4030 && INSN_P (maybe_cc0_setter)
4031 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
4032 insn = maybe_cc0_setter;
4035 /* FIXME: What if something in cc0/jump uses value set in new insn? */
4036 new_insn = emit_insn_before_noloc (pat, insn);
4039 /* Likewise if the last insn is a call, as will happen in the presence
4040 of exception handling. */
4041 else if (CALL_P (insn)
4042 && (!single_succ_p (bb)
4043 || single_succ_edge (bb)->flags & EDGE_ABNORMAL))
4045 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
4046 we search backward and place the instructions before the first
4047 parameter is loaded. Do this for everyone for consistency and a
4048 presumption that we'll get better code elsewhere as well.
4050 It should always be the case that we can put these instructions
4051 anywhere in the basic block with performing PRE optimizations.
4055 || TEST_BIT (antloc[bb->index], expr->bitmap_index)
4056 || TEST_BIT (transp[bb->index], expr->bitmap_index));
4058 /* Since different machines initialize their parameter registers
4059 in different orders, assume nothing. Collect the set of all
4060 parameter registers. */
4061 insn = find_first_parameter_load (insn, BB_HEAD (bb));
4063 /* If we found all the parameter loads, then we want to insert
4064 before the first parameter load.
4066 If we did not find all the parameter loads, then we might have
4067 stopped on the head of the block, which could be a CODE_LABEL.
4068 If we inserted before the CODE_LABEL, then we would be putting
4069 the insn in the wrong basic block. In that case, put the insn
4070 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
4071 while (LABEL_P (insn)
4072 || NOTE_INSN_BASIC_BLOCK_P (insn))
4073 insn = NEXT_INSN (insn);
4075 new_insn = emit_insn_before_noloc (pat, insn);
4078 new_insn = emit_insn_after_noloc (pat, insn);
4084 add_label_notes (PATTERN (pat), new_insn);
4085 note_stores (PATTERN (pat), record_set_info, pat);
4089 pat = NEXT_INSN (pat);
4092 gcse_create_count++;
4096 fprintf (dump_file, "PRE/HOIST: end of bb %d, insn %d, ",
4097 bb->index, INSN_UID (new_insn));
4098 fprintf (dump_file, "copying expression %d to reg %d\n",
4099 expr->bitmap_index, regno);
4103 /* Insert partially redundant expressions on edges in the CFG to make
4104 the expressions fully redundant. */
4107 pre_edge_insert (struct edge_list *edge_list, struct expr **index_map)
4109 int e, i, j, num_edges, set_size, did_insert = 0;
4112 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
4113 if it reaches any of the deleted expressions. */
4115 set_size = pre_insert_map[0]->size;
4116 num_edges = NUM_EDGES (edge_list);
4117 inserted = sbitmap_vector_alloc (num_edges, expr_hash_table.n_elems);
4118 sbitmap_vector_zero (inserted, num_edges);
4120 for (e = 0; e < num_edges; e++)
4123 basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
4125 for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
4127 SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
4129 for (j = indx; insert && j < (int) expr_hash_table.n_elems; j++, insert >>= 1)
4130 if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
4132 struct expr *expr = index_map[j];
4135 /* Now look at each deleted occurrence of this expression. */
4136 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4138 if (! occr->deleted_p)
4141 /* Insert this expression on this edge if it would
4142 reach the deleted occurrence in BB. */
4143 if (!TEST_BIT (inserted[e], j))
4146 edge eg = INDEX_EDGE (edge_list, e);
4148 /* We can't insert anything on an abnormal and
4149 critical edge, so we insert the insn at the end of
4150 the previous block. There are several alternatives
4151 detailed in Morgans book P277 (sec 10.5) for
4152 handling this situation. This one is easiest for
4155 if (eg->flags & EDGE_ABNORMAL)
4156 insert_insn_end_bb (index_map[j], bb, 0);
4159 insn = process_insert_insn (index_map[j]);
4160 insert_insn_on_edge (insn, eg);
4165 fprintf (dump_file, "PRE/HOIST: edge (%d,%d), ",
4167 INDEX_EDGE_SUCC_BB (edge_list, e)->index);
4168 fprintf (dump_file, "copy expression %d\n",
4169 expr->bitmap_index);
4172 update_ld_motion_stores (expr);
4173 SET_BIT (inserted[e], j);
4175 gcse_create_count++;
4182 sbitmap_vector_free (inserted);
4186 /* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
4187 Given "old_reg <- expr" (INSN), instead of adding after it
4188 reaching_reg <- old_reg
4189 it's better to do the following:
4190 reaching_reg <- expr
4191 old_reg <- reaching_reg
4192 because this way copy propagation can discover additional PRE
4193 opportunities. But if this fails, we try the old way.
4194 When "expr" is a store, i.e.
4195 given "MEM <- old_reg", instead of adding after it
4196 reaching_reg <- old_reg
4197 it's better to add it before as follows:
4198 reaching_reg <- old_reg
4199 MEM <- reaching_reg. */
4202 pre_insert_copy_insn (struct expr *expr, rtx insn)
4204 rtx reg = expr->reaching_reg;
4205 int regno = REGNO (reg);
4206 int indx = expr->bitmap_index;
4207 rtx pat = PATTERN (insn);
4208 rtx set, first_set, new_insn;
4212 /* This block matches the logic in hash_scan_insn. */
4213 switch (GET_CODE (pat))
4220 /* Search through the parallel looking for the set whose
4221 source was the expression that we're interested in. */
4222 first_set = NULL_RTX;
4224 for (i = 0; i < XVECLEN (pat, 0); i++)
4226 rtx x = XVECEXP (pat, 0, i);
4227 if (GET_CODE (x) == SET)
4229 /* If the source was a REG_EQUAL or REG_EQUIV note, we
4230 may not find an equivalent expression, but in this
4231 case the PARALLEL will have a single set. */
4232 if (first_set == NULL_RTX)
4234 if (expr_equiv_p (SET_SRC (x), expr->expr))
4242 gcc_assert (first_set);
4243 if (set == NULL_RTX)
4251 if (REG_P (SET_DEST (set)))
4253 old_reg = SET_DEST (set);
4254 /* Check if we can modify the set destination in the original insn. */
4255 if (validate_change (insn, &SET_DEST (set), reg, 0))
4257 new_insn = gen_move_insn (old_reg, reg);
4258 new_insn = emit_insn_after (new_insn, insn);
4260 /* Keep register set table up to date. */
4261 record_one_set (regno, insn);
4265 new_insn = gen_move_insn (reg, old_reg);
4266 new_insn = emit_insn_after (new_insn, insn);
4268 /* Keep register set table up to date. */
4269 record_one_set (regno, new_insn);
4272 else /* This is possible only in case of a store to memory. */
4274 old_reg = SET_SRC (set);
4275 new_insn = gen_move_insn (reg, old_reg);
4277 /* Check if we can modify the set source in the original insn. */
4278 if (validate_change (insn, &SET_SRC (set), reg, 0))
4279 new_insn = emit_insn_before (new_insn, insn);
4281 new_insn = emit_insn_after (new_insn, insn);
4283 /* Keep register set table up to date. */
4284 record_one_set (regno, new_insn);
4287 gcse_create_count++;
4291 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
4292 BLOCK_NUM (insn), INSN_UID (new_insn), indx,
4293 INSN_UID (insn), regno);
4296 /* Copy available expressions that reach the redundant expression
4297 to `reaching_reg'. */
4300 pre_insert_copies (void)
4302 unsigned int i, added_copy;
4307 /* For each available expression in the table, copy the result to
4308 `reaching_reg' if the expression reaches a deleted one.
4310 ??? The current algorithm is rather brute force.
4311 Need to do some profiling. */
4313 for (i = 0; i < expr_hash_table.size; i++)
4314 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
4316 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
4317 we don't want to insert a copy here because the expression may not
4318 really be redundant. So only insert an insn if the expression was
4319 deleted. This test also avoids further processing if the
4320 expression wasn't deleted anywhere. */
4321 if (expr->reaching_reg == NULL)
4324 /* Set when we add a copy for that expression. */
4327 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4329 if (! occr->deleted_p)
4332 for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
4334 rtx insn = avail->insn;
4336 /* No need to handle this one if handled already. */
4337 if (avail->copied_p)
4340 /* Don't handle this one if it's a redundant one. */
4341 if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
4344 /* Or if the expression doesn't reach the deleted one. */
4345 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
4347 BLOCK_FOR_INSN (occr->insn)))
4352 /* Copy the result of avail to reaching_reg. */
4353 pre_insert_copy_insn (expr, insn);
4354 avail->copied_p = 1;
4359 update_ld_motion_stores (expr);
4363 /* Emit move from SRC to DEST noting the equivalence with expression computed
4366 gcse_emit_move_after (rtx src, rtx dest, rtx insn)
4369 rtx set = single_set (insn), set2;
4373 /* This should never fail since we're creating a reg->reg copy
4374 we've verified to be valid. */
4376 new = emit_insn_after (gen_move_insn (dest, src), insn);
4378 /* Note the equivalence for local CSE pass. */
4379 set2 = single_set (new);
4380 if (!set2 || !rtx_equal_p (SET_DEST (set2), dest))
4382 if ((note = find_reg_equal_equiv_note (insn)))
4383 eqv = XEXP (note, 0);
4385 eqv = SET_SRC (set);
4387 set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (eqv));
4392 /* Delete redundant computations.
4393 Deletion is done by changing the insn to copy the `reaching_reg' of
4394 the expression into the result of the SET. It is left to later passes
4395 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
4397 Returns nonzero if a change is made. */
4408 for (i = 0; i < expr_hash_table.size; i++)
4409 for (expr = expr_hash_table.table[i];
4411 expr = expr->next_same_hash)
4413 int indx = expr->bitmap_index;
4415 /* We only need to search antic_occr since we require
4418 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4420 rtx insn = occr->insn;
4422 basic_block bb = BLOCK_FOR_INSN (insn);
4424 /* We only delete insns that have a single_set. */
4425 if (TEST_BIT (pre_delete_map[bb->index], indx)
4426 && (set = single_set (insn)) != 0)
4428 /* Create a pseudo-reg to store the result of reaching
4429 expressions into. Get the mode for the new pseudo from
4430 the mode of the original destination pseudo. */
4431 if (expr->reaching_reg == NULL)
4433 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
4435 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
4437 occr->deleted_p = 1;
4438 SET_BIT (pre_redundant_insns, INSN_CUID (insn));
4445 "PRE: redundant insn %d (expression %d) in ",
4446 INSN_UID (insn), indx);
4447 fprintf (dump_file, "bb %d, reaching reg is %d\n",
4448 bb->index, REGNO (expr->reaching_reg));
4457 /* Perform GCSE optimizations using PRE.
4458 This is called by one_pre_gcse_pass after all the dataflow analysis
4461 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
4462 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
4463 Compiler Design and Implementation.
4465 ??? A new pseudo reg is created to hold the reaching expression. The nice
4466 thing about the classical approach is that it would try to use an existing
4467 reg. If the register can't be adequately optimized [i.e. we introduce
4468 reload problems], one could add a pass here to propagate the new register
4471 ??? We don't handle single sets in PARALLELs because we're [currently] not
4472 able to copy the rest of the parallel when we insert copies to create full
4473 redundancies from partial redundancies. However, there's no reason why we
4474 can't handle PARALLELs in the cases where there are no partial
4481 int did_insert, changed;
4482 struct expr **index_map;
4485 /* Compute a mapping from expression number (`bitmap_index') to
4486 hash table entry. */
4488 index_map = XCNEWVEC (struct expr *, expr_hash_table.n_elems);
4489 for (i = 0; i < expr_hash_table.size; i++)
4490 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
4491 index_map[expr->bitmap_index] = expr;
4493 /* Reset bitmap used to track which insns are redundant. */
4494 pre_redundant_insns = sbitmap_alloc (max_cuid);
4495 sbitmap_zero (pre_redundant_insns);
4497 /* Delete the redundant insns first so that
4498 - we know what register to use for the new insns and for the other
4499 ones with reaching expressions
4500 - we know which insns are redundant when we go to create copies */
4502 changed = pre_delete ();
4504 did_insert = pre_edge_insert (edge_list, index_map);
4506 /* In other places with reaching expressions, copy the expression to the
4507 specially allocated pseudo-reg that reaches the redundant expr. */
4508 pre_insert_copies ();
4511 commit_edge_insertions ();
4516 sbitmap_free (pre_redundant_insns);
4520 /* Top level routine to perform one PRE GCSE pass.
4522 Return nonzero if a change was made. */
4525 one_pre_gcse_pass (int pass)
4529 gcse_subst_count = 0;
4530 gcse_create_count = 0;
4532 alloc_hash_table (max_cuid, &expr_hash_table, 0);
4533 add_noreturn_fake_exit_edges ();
4535 compute_ld_motion_mems ();
4537 compute_hash_table (&expr_hash_table);
4538 trim_ld_motion_mems ();
4540 dump_hash_table (dump_file, "Expression", &expr_hash_table);
4542 if (expr_hash_table.n_elems > 0)
4544 alloc_pre_mem (last_basic_block, expr_hash_table.n_elems);
4545 compute_pre_data ();
4546 changed |= pre_gcse ();
4547 free_edge_list (edge_list);
4552 remove_fake_exit_edges ();
4553 free_hash_table (&expr_hash_table);
4557 fprintf (dump_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
4558 current_function_name (), pass, bytes_used);
4559 fprintf (dump_file, "%d substs, %d insns created\n",
4560 gcse_subst_count, gcse_create_count);
4566 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
4567 If notes are added to an insn which references a CODE_LABEL, the
4568 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
4569 because the following loop optimization pass requires them. */
4571 /* ??? This is very similar to the loop.c add_label_notes function. We
4572 could probably share code here. */
4574 /* ??? If there was a jump optimization pass after gcse and before loop,
4575 then we would not need to do this here, because jump would add the
4576 necessary REG_LABEL notes. */
4579 add_label_notes (rtx x, rtx insn)
4581 enum rtx_code code = GET_CODE (x);
4585 if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
4587 /* This code used to ignore labels that referred to dispatch tables to
4588 avoid flow generating (slightly) worse code.
4590 We no longer ignore such label references (see LABEL_REF handling in
4591 mark_jump_label for additional information). */
4593 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0),
4595 if (LABEL_P (XEXP (x, 0)))
4596 LABEL_NUSES (XEXP (x, 0))++;
4600 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
4603 add_label_notes (XEXP (x, i), insn);
4604 else if (fmt[i] == 'E')
4605 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4606 add_label_notes (XVECEXP (x, i, j), insn);
4610 /* Compute transparent outgoing information for each block.
4612 An expression is transparent to an edge unless it is killed by
4613 the edge itself. This can only happen with abnormal control flow,
4614 when the edge is traversed through a call. This happens with
4615 non-local labels and exceptions.
4617 This would not be necessary if we split the edge. While this is
4618 normally impossible for abnormal critical edges, with some effort
4619 it should be possible with exception handling, since we still have
4620 control over which handler should be invoked. But due to increased
4621 EH table sizes, this may not be worthwhile. */
4624 compute_transpout (void)
4630 sbitmap_vector_ones (transpout, last_basic_block);
4634 /* Note that flow inserted a nop a the end of basic blocks that
4635 end in call instructions for reasons other than abnormal
4637 if (! CALL_P (BB_END (bb)))
4640 for (i = 0; i < expr_hash_table.size; i++)
4641 for (expr = expr_hash_table.table[i]; expr ; expr = expr->next_same_hash)
4642 if (MEM_P (expr->expr))
4644 if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
4645 && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
4648 /* ??? Optimally, we would use interprocedural alias
4649 analysis to determine if this mem is actually killed
4651 RESET_BIT (transpout[bb->index], expr->bitmap_index);
4656 /* Code Hoisting variables and subroutines. */
4658 /* Very busy expressions. */
4659 static sbitmap *hoist_vbein;
4660 static sbitmap *hoist_vbeout;
4662 /* Hoistable expressions. */
4663 static sbitmap *hoist_exprs;
4665 /* ??? We could compute post dominators and run this algorithm in
4666 reverse to perform tail merging, doing so would probably be
4667 more effective than the tail merging code in jump.c.
4669 It's unclear if tail merging could be run in parallel with
4670 code hoisting. It would be nice. */
4672 /* Allocate vars used for code hoisting analysis. */
4675 alloc_code_hoist_mem (int n_blocks, int n_exprs)
4677 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
4678 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
4679 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
4681 hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
4682 hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
4683 hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
4684 transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
4687 /* Free vars used for code hoisting analysis. */
4690 free_code_hoist_mem (void)
4692 sbitmap_vector_free (antloc);
4693 sbitmap_vector_free (transp);
4694 sbitmap_vector_free (comp);
4696 sbitmap_vector_free (hoist_vbein);
4697 sbitmap_vector_free (hoist_vbeout);
4698 sbitmap_vector_free (hoist_exprs);
4699 sbitmap_vector_free (transpout);
4701 free_dominance_info (CDI_DOMINATORS);
4704 /* Compute the very busy expressions at entry/exit from each block.
4706 An expression is very busy if all paths from a given point
4707 compute the expression. */
4710 compute_code_hoist_vbeinout (void)
4712 int changed, passes;
4715 sbitmap_vector_zero (hoist_vbeout, last_basic_block);
4716 sbitmap_vector_zero (hoist_vbein, last_basic_block);
4725 /* We scan the blocks in the reverse order to speed up
4727 FOR_EACH_BB_REVERSE (bb)
4729 changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index], antloc[bb->index],
4730 hoist_vbeout[bb->index], transp[bb->index]);
4731 if (bb->next_bb != EXIT_BLOCK_PTR)
4732 sbitmap_intersection_of_succs (hoist_vbeout[bb->index], hoist_vbein, bb->index);
4739 fprintf (dump_file, "hoisting vbeinout computation: %d passes\n", passes);
4742 /* Top level routine to do the dataflow analysis needed by code hoisting. */
4745 compute_code_hoist_data (void)
4747 compute_local_properties (transp, comp, antloc, &expr_hash_table);
4748 compute_transpout ();
4749 compute_code_hoist_vbeinout ();
4750 calculate_dominance_info (CDI_DOMINATORS);
4752 fprintf (dump_file, "\n");
4755 /* Determine if the expression identified by EXPR_INDEX would
4756 reach BB unimpared if it was placed at the end of EXPR_BB.
4758 It's unclear exactly what Muchnick meant by "unimpared". It seems
4759 to me that the expression must either be computed or transparent in
4760 *every* block in the path(s) from EXPR_BB to BB. Any other definition
4761 would allow the expression to be hoisted out of loops, even if
4762 the expression wasn't a loop invariant.
4764 Contrast this to reachability for PRE where an expression is
4765 considered reachable if *any* path reaches instead of *all*
4769 hoist_expr_reaches_here_p (basic_block expr_bb, int expr_index, basic_block bb, char *visited)
4773 int visited_allocated_locally = 0;
4776 if (visited == NULL)
4778 visited_allocated_locally = 1;
4779 visited = XCNEWVEC (char, last_basic_block);
4782 FOR_EACH_EDGE (pred, ei, bb->preds)
4784 basic_block pred_bb = pred->src;
4786 if (pred->src == ENTRY_BLOCK_PTR)
4788 else if (pred_bb == expr_bb)
4790 else if (visited[pred_bb->index])
4793 /* Does this predecessor generate this expression? */
4794 else if (TEST_BIT (comp[pred_bb->index], expr_index))
4796 else if (! TEST_BIT (transp[pred_bb->index], expr_index))
4802 visited[pred_bb->index] = 1;
4803 if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
4808 if (visited_allocated_locally)
4811 return (pred == NULL);
4814 /* Actually perform code hoisting. */
4819 basic_block bb, dominated;
4821 unsigned int domby_len;
4823 struct expr **index_map;
4826 sbitmap_vector_zero (hoist_exprs, last_basic_block);
4828 /* Compute a mapping from expression number (`bitmap_index') to
4829 hash table entry. */
4831 index_map = XCNEWVEC (struct expr *, expr_hash_table.n_elems);
4832 for (i = 0; i < expr_hash_table.size; i++)
4833 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
4834 index_map[expr->bitmap_index] = expr;
4836 /* Walk over each basic block looking for potentially hoistable
4837 expressions, nothing gets hoisted from the entry block. */
4841 int insn_inserted_p;
4843 domby_len = get_dominated_by (CDI_DOMINATORS, bb, &domby);
4844 /* Examine each expression that is very busy at the exit of this
4845 block. These are the potentially hoistable expressions. */
4846 for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++)
4850 if (TEST_BIT (hoist_vbeout[bb->index], i)
4851 && TEST_BIT (transpout[bb->index], i))
4853 /* We've found a potentially hoistable expression, now
4854 we look at every block BB dominates to see if it
4855 computes the expression. */
4856 for (j = 0; j < domby_len; j++)
4858 dominated = domby[j];
4859 /* Ignore self dominance. */
4860 if (bb == dominated)
4862 /* We've found a dominated block, now see if it computes
4863 the busy expression and whether or not moving that
4864 expression to the "beginning" of that block is safe. */
4865 if (!TEST_BIT (antloc[dominated->index], i))
4868 /* Note if the expression would reach the dominated block
4869 unimpared if it was placed at the end of BB.
4871 Keep track of how many times this expression is hoistable
4872 from a dominated block into BB. */
4873 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
4877 /* If we found more than one hoistable occurrence of this
4878 expression, then note it in the bitmap of expressions to
4879 hoist. It makes no sense to hoist things which are computed
4880 in only one BB, and doing so tends to pessimize register
4881 allocation. One could increase this value to try harder
4882 to avoid any possible code expansion due to register
4883 allocation issues; however experiments have shown that
4884 the vast majority of hoistable expressions are only movable
4885 from two successors, so raising this threshold is likely
4886 to nullify any benefit we get from code hoisting. */
4889 SET_BIT (hoist_exprs[bb->index], i);
4894 /* If we found nothing to hoist, then quit now. */
4901 /* Loop over all the hoistable expressions. */
4902 for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++)
4904 /* We want to insert the expression into BB only once, so
4905 note when we've inserted it. */
4906 insn_inserted_p = 0;
4908 /* These tests should be the same as the tests above. */
4909 if (TEST_BIT (hoist_exprs[bb->index], i))
4911 /* We've found a potentially hoistable expression, now
4912 we look at every block BB dominates to see if it
4913 computes the expression. */
4914 for (j = 0; j < domby_len; j++)
4916 dominated = domby[j];
4917 /* Ignore self dominance. */
4918 if (bb == dominated)
4921 /* We've found a dominated block, now see if it computes
4922 the busy expression and whether or not moving that
4923 expression to the "beginning" of that block is safe. */
4924 if (!TEST_BIT (antloc[dominated->index], i))
4927 /* The expression is computed in the dominated block and
4928 it would be safe to compute it at the start of the
4929 dominated block. Now we have to determine if the
4930 expression would reach the dominated block if it was
4931 placed at the end of BB. */
4932 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
4934 struct expr *expr = index_map[i];
4935 struct occr *occr = expr->antic_occr;
4939 /* Find the right occurrence of this expression. */
4940 while (BLOCK_FOR_INSN (occr->insn) != dominated && occr)
4945 set = single_set (insn);
4948 /* Create a pseudo-reg to store the result of reaching
4949 expressions into. Get the mode for the new pseudo
4950 from the mode of the original destination pseudo. */
4951 if (expr->reaching_reg == NULL)
4953 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
4955 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
4957 occr->deleted_p = 1;
4958 if (!insn_inserted_p)
4960 insert_insn_end_bb (index_map[i], bb, 0);
4961 insn_inserted_p = 1;
4973 /* Top level routine to perform one code hoisting (aka unification) pass
4975 Return nonzero if a change was made. */
4978 one_code_hoisting_pass (void)
4982 alloc_hash_table (max_cuid, &expr_hash_table, 0);
4983 compute_hash_table (&expr_hash_table);
4985 dump_hash_table (dump_file, "Code Hosting Expressions", &expr_hash_table);
4987 if (expr_hash_table.n_elems > 0)
4989 alloc_code_hoist_mem (last_basic_block, expr_hash_table.n_elems);
4990 compute_code_hoist_data ();
4992 free_code_hoist_mem ();
4995 free_hash_table (&expr_hash_table);
5000 /* Here we provide the things required to do store motion towards
5001 the exit. In order for this to be effective, gcse also needed to
5002 be taught how to move a load when it is kill only by a store to itself.
5007 void foo(float scale)
5009 for (i=0; i<10; i++)
5013 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
5014 the load out since its live around the loop, and stored at the bottom
5017 The 'Load Motion' referred to and implemented in this file is
5018 an enhancement to gcse which when using edge based lcm, recognizes
5019 this situation and allows gcse to move the load out of the loop.
5021 Once gcse has hoisted the load, store motion can then push this
5022 load towards the exit, and we end up with no loads or stores of 'i'
5026 pre_ldst_expr_hash (const void *p)
5028 int do_not_record_p = 0;
5029 const struct ls_expr *x = p;
5030 return hash_rtx (x->pattern, GET_MODE (x->pattern), &do_not_record_p, NULL, false);
5034 pre_ldst_expr_eq (const void *p1, const void *p2)
5036 const struct ls_expr *ptr1 = p1, *ptr2 = p2;
5037 return expr_equiv_p (ptr1->pattern, ptr2->pattern);
5040 /* This will search the ldst list for a matching expression. If it
5041 doesn't find one, we create one and initialize it. */
5043 static struct ls_expr *
5046 int do_not_record_p = 0;
5047 struct ls_expr * ptr;
5052 hash = hash_rtx (x, GET_MODE (x), &do_not_record_p,
5053 NULL, /*have_reg_qty=*/false);
5056 slot = htab_find_slot_with_hash (pre_ldst_table, &e, hash, INSERT);
5058 return (struct ls_expr *)*slot;
5060 ptr = XNEW (struct ls_expr);
5062 ptr->next = pre_ldst_mems;
5065 ptr->pattern_regs = NULL_RTX;
5066 ptr->loads = NULL_RTX;
5067 ptr->stores = NULL_RTX;
5068 ptr->reaching_reg = NULL_RTX;
5071 ptr->hash_index = hash;
5072 pre_ldst_mems = ptr;
5078 /* Free up an individual ldst entry. */
5081 free_ldst_entry (struct ls_expr * ptr)
5083 free_INSN_LIST_list (& ptr->loads);
5084 free_INSN_LIST_list (& ptr->stores);
5089 /* Free up all memory associated with the ldst list. */
5092 free_ldst_mems (void)
5095 htab_delete (pre_ldst_table);
5096 pre_ldst_table = NULL;
5098 while (pre_ldst_mems)
5100 struct ls_expr * tmp = pre_ldst_mems;
5102 pre_ldst_mems = pre_ldst_mems->next;
5104 free_ldst_entry (tmp);
5107 pre_ldst_mems = NULL;
5110 /* Dump debugging info about the ldst list. */
5113 print_ldst_list (FILE * file)
5115 struct ls_expr * ptr;
5117 fprintf (file, "LDST list: \n");
5119 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
5121 fprintf (file, " Pattern (%3d): ", ptr->index);
5123 print_rtl (file, ptr->pattern);
5125 fprintf (file, "\n Loads : ");
5128 print_rtl (file, ptr->loads);
5130 fprintf (file, "(nil)");
5132 fprintf (file, "\n Stores : ");
5135 print_rtl (file, ptr->stores);
5137 fprintf (file, "(nil)");
5139 fprintf (file, "\n\n");
5142 fprintf (file, "\n");
5145 /* Returns 1 if X is in the list of ldst only expressions. */
5147 static struct ls_expr *
5148 find_rtx_in_ldst (rtx x)
5152 if (!pre_ldst_table)
5155 slot = htab_find_slot (pre_ldst_table, &e, NO_INSERT);
5156 if (!slot || ((struct ls_expr *)*slot)->invalid)
5161 /* Assign each element of the list of mems a monotonically increasing value. */
5164 enumerate_ldsts (void)
5166 struct ls_expr * ptr;
5169 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
5175 /* Return first item in the list. */
5177 static inline struct ls_expr *
5178 first_ls_expr (void)
5180 return pre_ldst_mems;
5183 /* Return the next item in the list after the specified one. */
5185 static inline struct ls_expr *
5186 next_ls_expr (struct ls_expr * ptr)
5191 /* Load Motion for loads which only kill themselves. */
5193 /* Return true if x is a simple MEM operation, with no registers or
5194 side effects. These are the types of loads we consider for the
5195 ld_motion list, otherwise we let the usual aliasing take care of it. */
5203 if (MEM_VOLATILE_P (x))
5206 if (GET_MODE (x) == BLKmode)
5209 /* If we are handling exceptions, we must be careful with memory references
5210 that may trap. If we are not, the behavior is undefined, so we may just
5212 if (flag_non_call_exceptions && may_trap_p (x))
5215 if (side_effects_p (x))
5218 /* Do not consider function arguments passed on stack. */
5219 if (reg_mentioned_p (stack_pointer_rtx, x))
5222 if (flag_float_store && FLOAT_MODE_P (GET_MODE (x)))
5228 /* Make sure there isn't a buried reference in this pattern anywhere.
5229 If there is, invalidate the entry for it since we're not capable
5230 of fixing it up just yet.. We have to be sure we know about ALL
5231 loads since the aliasing code will allow all entries in the
5232 ld_motion list to not-alias itself. If we miss a load, we will get
5233 the wrong value since gcse might common it and we won't know to
5237 invalidate_any_buried_refs (rtx x)
5241 struct ls_expr * ptr;
5243 /* Invalidate it in the list. */
5244 if (MEM_P (x) && simple_mem (x))
5246 ptr = ldst_entry (x);
5250 /* Recursively process the insn. */
5251 fmt = GET_RTX_FORMAT (GET_CODE (x));
5253 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
5256 invalidate_any_buried_refs (XEXP (x, i));
5257 else if (fmt[i] == 'E')
5258 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5259 invalidate_any_buried_refs (XVECEXP (x, i, j));
5263 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
5264 being defined as MEM loads and stores to symbols, with no side effects
5265 and no registers in the expression. For a MEM destination, we also
5266 check that the insn is still valid if we replace the destination with a
5267 REG, as is done in update_ld_motion_stores. If there are any uses/defs
5268 which don't match this criteria, they are invalidated and trimmed out
5272 compute_ld_motion_mems (void)
5274 struct ls_expr * ptr;
5278 pre_ldst_mems = NULL;
5279 pre_ldst_table = htab_create (13, pre_ldst_expr_hash,
5280 pre_ldst_expr_eq, NULL);
5284 FOR_BB_INSNS (bb, insn)
5288 if (GET_CODE (PATTERN (insn)) == SET)
5290 rtx src = SET_SRC (PATTERN (insn));
5291 rtx dest = SET_DEST (PATTERN (insn));
5293 /* Check for a simple LOAD... */
5294 if (MEM_P (src) && simple_mem (src))
5296 ptr = ldst_entry (src);
5298 ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
5304 /* Make sure there isn't a buried load somewhere. */
5305 invalidate_any_buried_refs (src);
5308 /* Check for stores. Don't worry about aliased ones, they
5309 will block any movement we might do later. We only care
5310 about this exact pattern since those are the only
5311 circumstance that we will ignore the aliasing info. */
5312 if (MEM_P (dest) && simple_mem (dest))
5314 ptr = ldst_entry (dest);
5317 && GET_CODE (src) != ASM_OPERANDS
5318 /* Check for REG manually since want_to_gcse_p
5319 returns 0 for all REGs. */
5320 && can_assign_to_reg_p (src))
5321 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
5327 invalidate_any_buried_refs (PATTERN (insn));
5333 /* Remove any references that have been either invalidated or are not in the
5334 expression list for pre gcse. */
5337 trim_ld_motion_mems (void)
5339 struct ls_expr * * last = & pre_ldst_mems;
5340 struct ls_expr * ptr = pre_ldst_mems;
5346 /* Delete if entry has been made invalid. */
5349 /* Delete if we cannot find this mem in the expression list. */
5350 unsigned int hash = ptr->hash_index % expr_hash_table.size;
5352 for (expr = expr_hash_table.table[hash];
5354 expr = expr->next_same_hash)
5355 if (expr_equiv_p (expr->expr, ptr->pattern))
5359 expr = (struct expr *) 0;
5363 /* Set the expression field if we are keeping it. */
5371 htab_remove_elt_with_hash (pre_ldst_table, ptr, ptr->hash_index);
5372 free_ldst_entry (ptr);
5377 /* Show the world what we've found. */
5378 if (dump_file && pre_ldst_mems != NULL)
5379 print_ldst_list (dump_file);
5382 /* This routine will take an expression which we are replacing with
5383 a reaching register, and update any stores that are needed if
5384 that expression is in the ld_motion list. Stores are updated by
5385 copying their SRC to the reaching register, and then storing
5386 the reaching register into the store location. These keeps the
5387 correct value in the reaching register for the loads. */
5390 update_ld_motion_stores (struct expr * expr)
5392 struct ls_expr * mem_ptr;
5394 if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
5396 /* We can try to find just the REACHED stores, but is shouldn't
5397 matter to set the reaching reg everywhere... some might be
5398 dead and should be eliminated later. */
5400 /* We replace (set mem expr) with (set reg expr) (set mem reg)
5401 where reg is the reaching reg used in the load. We checked in
5402 compute_ld_motion_mems that we can replace (set mem expr) with
5403 (set reg expr) in that insn. */
5404 rtx list = mem_ptr->stores;
5406 for ( ; list != NULL_RTX; list = XEXP (list, 1))
5408 rtx insn = XEXP (list, 0);
5409 rtx pat = PATTERN (insn);
5410 rtx src = SET_SRC (pat);
5411 rtx reg = expr->reaching_reg;
5414 /* If we've already copied it, continue. */
5415 if (expr->reaching_reg == src)
5420 fprintf (dump_file, "PRE: store updated with reaching reg ");
5421 print_rtl (dump_file, expr->reaching_reg);
5422 fprintf (dump_file, ":\n ");
5423 print_inline_rtx (dump_file, insn, 8);
5424 fprintf (dump_file, "\n");
5427 copy = gen_move_insn ( reg, copy_rtx (SET_SRC (pat)));
5428 new = emit_insn_before (copy, insn);
5429 record_one_set (REGNO (reg), new);
5430 SET_SRC (pat) = reg;
5432 /* un-recognize this pattern since it's probably different now. */
5433 INSN_CODE (insn) = -1;
5434 gcse_create_count++;
5439 /* Store motion code. */
5441 #define ANTIC_STORE_LIST(x) ((x)->loads)
5442 #define AVAIL_STORE_LIST(x) ((x)->stores)
5443 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
5445 /* This is used to communicate the target bitvector we want to use in the
5446 reg_set_info routine when called via the note_stores mechanism. */
5447 static int * regvec;
5449 /* And current insn, for the same routine. */
5450 static rtx compute_store_table_current_insn;
5452 /* Used in computing the reverse edge graph bit vectors. */
5453 static sbitmap * st_antloc;
5455 /* Global holding the number of store expressions we are dealing with. */
5456 static int num_stores;
5458 /* Checks to set if we need to mark a register set. Called from
5462 reg_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED,
5465 sbitmap bb_reg = data;
5467 if (GET_CODE (dest) == SUBREG)
5468 dest = SUBREG_REG (dest);
5472 regvec[REGNO (dest)] = INSN_UID (compute_store_table_current_insn);
5474 SET_BIT (bb_reg, REGNO (dest));
5478 /* Clear any mark that says that this insn sets dest. Called from
5482 reg_clear_last_set (rtx dest, rtx setter ATTRIBUTE_UNUSED,
5485 int *dead_vec = data;
5487 if (GET_CODE (dest) == SUBREG)
5488 dest = SUBREG_REG (dest);
5491 dead_vec[REGNO (dest)] == INSN_UID (compute_store_table_current_insn))
5492 dead_vec[REGNO (dest)] = 0;
5495 /* Return zero if some of the registers in list X are killed
5496 due to set of registers in bitmap REGS_SET. */
5499 store_ops_ok (rtx x, int *regs_set)
5503 for (; x; x = XEXP (x, 1))
5506 if (regs_set[REGNO(reg)])
5513 /* Returns a list of registers mentioned in X. */
5515 extract_mentioned_regs (rtx x)
5517 return extract_mentioned_regs_helper (x, NULL_RTX);
5520 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
5523 extract_mentioned_regs_helper (rtx x, rtx accum)
5529 /* Repeat is used to turn tail-recursion into iteration. */
5535 code = GET_CODE (x);
5539 return alloc_EXPR_LIST (0, x, accum);
5549 /* We do not run this function with arguments having side effects. */
5568 i = GET_RTX_LENGTH (code) - 1;
5569 fmt = GET_RTX_FORMAT (code);
5575 rtx tem = XEXP (x, i);
5577 /* If we are about to do the last recursive call
5578 needed at this level, change it into iteration. */
5585 accum = extract_mentioned_regs_helper (tem, accum);
5587 else if (fmt[i] == 'E')
5591 for (j = 0; j < XVECLEN (x, i); j++)
5592 accum = extract_mentioned_regs_helper (XVECEXP (x, i, j), accum);
5599 /* Determine whether INSN is MEM store pattern that we will consider moving.
5600 REGS_SET_BEFORE is bitmap of registers set before (and including) the
5601 current insn, REGS_SET_AFTER is bitmap of registers set after (and
5602 including) the insn in this basic block. We must be passing through BB from
5603 head to end, as we are using this fact to speed things up.
5605 The results are stored this way:
5607 -- the first anticipatable expression is added into ANTIC_STORE_LIST
5608 -- if the processed expression is not anticipatable, NULL_RTX is added
5609 there instead, so that we can use it as indicator that no further
5610 expression of this type may be anticipatable
5611 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
5612 consequently, all of them but this head are dead and may be deleted.
5613 -- if the expression is not available, the insn due to that it fails to be
5614 available is stored in reaching_reg.
5616 The things are complicated a bit by fact that there already may be stores
5617 to the same MEM from other blocks; also caller must take care of the
5618 necessary cleanup of the temporary markers after end of the basic block.
5622 find_moveable_store (rtx insn, int *regs_set_before, int *regs_set_after)
5624 struct ls_expr * ptr;
5626 int check_anticipatable, check_available;
5627 basic_block bb = BLOCK_FOR_INSN (insn);
5629 set = single_set (insn);
5633 dest = SET_DEST (set);
5635 if (! MEM_P (dest) || MEM_VOLATILE_P (dest)
5636 || GET_MODE (dest) == BLKmode)
5639 if (side_effects_p (dest))
5642 /* If we are handling exceptions, we must be careful with memory references
5643 that may trap. If we are not, the behavior is undefined, so we may just
5645 if (flag_non_call_exceptions && may_trap_p (dest))
5648 /* Even if the destination cannot trap, the source may. In this case we'd
5649 need to handle updating the REG_EH_REGION note. */
5650 if (find_reg_note (insn, REG_EH_REGION, NULL_RTX))
5653 /* Make sure that the SET_SRC of this store insns can be assigned to
5654 a register, or we will fail later on in replace_store_insn, which
5655 assumes that we can do this. But sometimes the target machine has
5656 oddities like MEM read-modify-write instruction. See for example
5658 if (!can_assign_to_reg_p (SET_SRC (set)))
5661 ptr = ldst_entry (dest);
5662 if (!ptr->pattern_regs)
5663 ptr->pattern_regs = extract_mentioned_regs (dest);
5665 /* Do not check for anticipatability if we either found one anticipatable
5666 store already, or tested for one and found out that it was killed. */
5667 check_anticipatable = 0;
5668 if (!ANTIC_STORE_LIST (ptr))
5669 check_anticipatable = 1;
5672 tmp = XEXP (ANTIC_STORE_LIST (ptr), 0);
5674 && BLOCK_FOR_INSN (tmp) != bb)
5675 check_anticipatable = 1;
5677 if (check_anticipatable)
5679 if (store_killed_before (dest, ptr->pattern_regs, insn, bb, regs_set_before))
5683 ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (tmp,
5684 ANTIC_STORE_LIST (ptr));
5687 /* It is not necessary to check whether store is available if we did
5688 it successfully before; if we failed before, do not bother to check
5689 until we reach the insn that caused us to fail. */
5690 check_available = 0;
5691 if (!AVAIL_STORE_LIST (ptr))
5692 check_available = 1;
5695 tmp = XEXP (AVAIL_STORE_LIST (ptr), 0);
5696 if (BLOCK_FOR_INSN (tmp) != bb)
5697 check_available = 1;
5699 if (check_available)
5701 /* Check that we have already reached the insn at that the check
5702 failed last time. */
5703 if (LAST_AVAIL_CHECK_FAILURE (ptr))
5705 for (tmp = BB_END (bb);
5706 tmp != insn && tmp != LAST_AVAIL_CHECK_FAILURE (ptr);
5707 tmp = PREV_INSN (tmp))
5710 check_available = 0;
5713 check_available = store_killed_after (dest, ptr->pattern_regs, insn,
5715 &LAST_AVAIL_CHECK_FAILURE (ptr));
5717 if (!check_available)
5718 AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn, AVAIL_STORE_LIST (ptr));
5721 /* Find available and anticipatable stores. */
5724 compute_store_table (void)
5730 int *last_set_in, *already_set;
5731 struct ls_expr * ptr, **prev_next_ptr_ptr;
5733 max_gcse_regno = max_reg_num ();
5735 reg_set_in_block = sbitmap_vector_alloc (last_basic_block,
5737 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
5739 pre_ldst_table = htab_create (13, pre_ldst_expr_hash,
5740 pre_ldst_expr_eq, NULL);
5741 last_set_in = XCNEWVEC (int, max_gcse_regno);
5742 already_set = XNEWVEC (int, max_gcse_regno);
5744 /* Find all the stores we care about. */
5747 /* First compute the registers set in this block. */
5748 regvec = last_set_in;
5750 FOR_BB_INSNS (bb, insn)
5752 if (! INSN_P (insn))
5757 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
5758 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
5760 last_set_in[regno] = INSN_UID (insn);
5761 SET_BIT (reg_set_in_block[bb->index], regno);
5765 pat = PATTERN (insn);
5766 compute_store_table_current_insn = insn;
5767 note_stores (pat, reg_set_info, reg_set_in_block[bb->index]);
5770 /* Now find the stores. */
5771 memset (already_set, 0, sizeof (int) * max_gcse_regno);
5772 regvec = already_set;
5773 FOR_BB_INSNS (bb, insn)
5775 if (! INSN_P (insn))
5780 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
5781 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
5782 already_set[regno] = 1;
5785 pat = PATTERN (insn);
5786 note_stores (pat, reg_set_info, NULL);
5788 /* Now that we've marked regs, look for stores. */
5789 find_moveable_store (insn, already_set, last_set_in);
5791 /* Unmark regs that are no longer set. */
5792 compute_store_table_current_insn = insn;
5793 note_stores (pat, reg_clear_last_set, last_set_in);
5796 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
5797 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno)
5798 && last_set_in[regno] == INSN_UID (insn))
5799 last_set_in[regno] = 0;
5803 #ifdef ENABLE_CHECKING
5804 /* last_set_in should now be all-zero. */
5805 for (regno = 0; regno < max_gcse_regno; regno++)
5806 gcc_assert (!last_set_in[regno]);
5809 /* Clear temporary marks. */
5810 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
5812 LAST_AVAIL_CHECK_FAILURE(ptr) = NULL_RTX;
5813 if (ANTIC_STORE_LIST (ptr)
5814 && (tmp = XEXP (ANTIC_STORE_LIST (ptr), 0)) == NULL_RTX)
5815 ANTIC_STORE_LIST (ptr) = XEXP (ANTIC_STORE_LIST (ptr), 1);
5819 /* Remove the stores that are not available anywhere, as there will
5820 be no opportunity to optimize them. */
5821 for (ptr = pre_ldst_mems, prev_next_ptr_ptr = &pre_ldst_mems;
5823 ptr = *prev_next_ptr_ptr)
5825 if (!AVAIL_STORE_LIST (ptr))
5827 *prev_next_ptr_ptr = ptr->next;
5828 htab_remove_elt_with_hash (pre_ldst_table, ptr, ptr->hash_index);
5829 free_ldst_entry (ptr);
5832 prev_next_ptr_ptr = &ptr->next;
5835 ret = enumerate_ldsts ();
5839 fprintf (dump_file, "ST_avail and ST_antic (shown under loads..)\n");
5840 print_ldst_list (dump_file);
5848 /* Check to see if the load X is aliased with STORE_PATTERN.
5849 AFTER is true if we are checking the case when STORE_PATTERN occurs
5853 load_kills_store (rtx x, rtx store_pattern, int after)
5856 return anti_dependence (x, store_pattern);
5858 return true_dependence (store_pattern, GET_MODE (store_pattern), x,
5862 /* Go through the entire insn X, looking for any loads which might alias
5863 STORE_PATTERN. Return true if found.
5864 AFTER is true if we are checking the case when STORE_PATTERN occurs
5865 after the insn X. */
5868 find_loads (rtx x, rtx store_pattern, int after)
5877 if (GET_CODE (x) == SET)
5882 if (load_kills_store (x, store_pattern, after))
5886 /* Recursively process the insn. */
5887 fmt = GET_RTX_FORMAT (GET_CODE (x));
5889 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
5892 ret |= find_loads (XEXP (x, i), store_pattern, after);
5893 else if (fmt[i] == 'E')
5894 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5895 ret |= find_loads (XVECEXP (x, i, j), store_pattern, after);
5900 /* Check if INSN kills the store pattern X (is aliased with it).
5901 AFTER is true if we are checking the case when store X occurs
5902 after the insn. Return true if it does. */
5905 store_killed_in_insn (rtx x, rtx x_regs, rtx insn, int after)
5907 rtx reg, base, note;
5914 /* A normal or pure call might read from pattern,
5915 but a const call will not. */
5916 if (! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn))
5919 /* But even a const call reads its parameters. Check whether the
5920 base of some of registers used in mem is stack pointer. */
5921 for (reg = x_regs; reg; reg = XEXP (reg, 1))
5923 base = find_base_term (XEXP (reg, 0));
5925 || (GET_CODE (base) == ADDRESS
5926 && GET_MODE (base) == Pmode
5927 && XEXP (base, 0) == stack_pointer_rtx))
5934 if (GET_CODE (PATTERN (insn)) == SET)
5936 rtx pat = PATTERN (insn);
5937 rtx dest = SET_DEST (pat);
5939 if (GET_CODE (dest) == ZERO_EXTRACT)
5940 dest = XEXP (dest, 0);
5942 /* Check for memory stores to aliased objects. */
5944 && !expr_equiv_p (dest, x))
5948 if (output_dependence (dest, x))
5953 if (output_dependence (x, dest))
5957 if (find_loads (SET_SRC (pat), x, after))
5960 else if (find_loads (PATTERN (insn), x, after))
5963 /* If this insn has a REG_EQUAL or REG_EQUIV note referencing a memory
5964 location aliased with X, then this insn kills X. */
5965 note = find_reg_equal_equiv_note (insn);
5968 note = XEXP (note, 0);
5970 /* However, if the note represents a must alias rather than a may
5971 alias relationship, then it does not kill X. */
5972 if (expr_equiv_p (note, x))
5975 /* See if there are any aliased loads in the note. */
5976 return find_loads (note, x, after);
5979 /* Returns true if the expression X is loaded or clobbered on or after INSN
5980 within basic block BB. REGS_SET_AFTER is bitmap of registers set in
5981 or after the insn. X_REGS is list of registers mentioned in X. If the store
5982 is killed, return the last insn in that it occurs in FAIL_INSN. */
5985 store_killed_after (rtx x, rtx x_regs, rtx insn, basic_block bb,
5986 int *regs_set_after, rtx *fail_insn)
5988 rtx last = BB_END (bb), act;
5990 if (!store_ops_ok (x_regs, regs_set_after))
5992 /* We do not know where it will happen. */
5994 *fail_insn = NULL_RTX;
5998 /* Scan from the end, so that fail_insn is determined correctly. */
5999 for (act = last; act != PREV_INSN (insn); act = PREV_INSN (act))
6000 if (store_killed_in_insn (x, x_regs, act, false))
6010 /* Returns true if the expression X is loaded or clobbered on or before INSN
6011 within basic block BB. X_REGS is list of registers mentioned in X.
6012 REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
6014 store_killed_before (rtx x, rtx x_regs, rtx insn, basic_block bb,
6015 int *regs_set_before)
6017 rtx first = BB_HEAD (bb);
6019 if (!store_ops_ok (x_regs, regs_set_before))
6022 for ( ; insn != PREV_INSN (first); insn = PREV_INSN (insn))
6023 if (store_killed_in_insn (x, x_regs, insn, true))
6029 /* Fill in available, anticipatable, transparent and kill vectors in
6030 STORE_DATA, based on lists of available and anticipatable stores. */
6032 build_store_vectors (void)
6035 int *regs_set_in_block;
6037 struct ls_expr * ptr;
6040 /* Build the gen_vector. This is any store in the table which is not killed
6041 by aliasing later in its block. */
6042 ae_gen = sbitmap_vector_alloc (last_basic_block, num_stores);
6043 sbitmap_vector_zero (ae_gen, last_basic_block);
6045 st_antloc = sbitmap_vector_alloc (last_basic_block, num_stores);
6046 sbitmap_vector_zero (st_antloc, last_basic_block);
6048 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6050 for (st = AVAIL_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
6052 insn = XEXP (st, 0);
6053 bb = BLOCK_FOR_INSN (insn);
6055 /* If we've already seen an available expression in this block,
6056 we can delete this one (It occurs earlier in the block). We'll
6057 copy the SRC expression to an unused register in case there
6058 are any side effects. */
6059 if (TEST_BIT (ae_gen[bb->index], ptr->index))
6061 rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
6063 fprintf (dump_file, "Removing redundant store:\n");
6064 replace_store_insn (r, XEXP (st, 0), bb, ptr);
6067 SET_BIT (ae_gen[bb->index], ptr->index);
6070 for (st = ANTIC_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
6072 insn = XEXP (st, 0);
6073 bb = BLOCK_FOR_INSN (insn);
6074 SET_BIT (st_antloc[bb->index], ptr->index);
6078 ae_kill = sbitmap_vector_alloc (last_basic_block, num_stores);
6079 sbitmap_vector_zero (ae_kill, last_basic_block);
6081 transp = sbitmap_vector_alloc (last_basic_block, num_stores);
6082 sbitmap_vector_zero (transp, last_basic_block);
6083 regs_set_in_block = XNEWVEC (int, max_gcse_regno);
6087 for (regno = 0; regno < max_gcse_regno; regno++)
6088 regs_set_in_block[regno] = TEST_BIT (reg_set_in_block[bb->index], regno);
6090 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6092 if (store_killed_after (ptr->pattern, ptr->pattern_regs, BB_HEAD (bb),
6093 bb, regs_set_in_block, NULL))
6095 /* It should not be necessary to consider the expression
6096 killed if it is both anticipatable and available. */
6097 if (!TEST_BIT (st_antloc[bb->index], ptr->index)
6098 || !TEST_BIT (ae_gen[bb->index], ptr->index))
6099 SET_BIT (ae_kill[bb->index], ptr->index);
6102 SET_BIT (transp[bb->index], ptr->index);
6106 free (regs_set_in_block);
6110 dump_sbitmap_vector (dump_file, "st_antloc", "", st_antloc, last_basic_block);
6111 dump_sbitmap_vector (dump_file, "st_kill", "", ae_kill, last_basic_block);
6112 dump_sbitmap_vector (dump_file, "Transpt", "", transp, last_basic_block);
6113 dump_sbitmap_vector (dump_file, "st_avloc", "", ae_gen, last_basic_block);
6117 /* Insert an instruction at the beginning of a basic block, and update
6118 the BB_HEAD if needed. */
6121 insert_insn_start_bb (rtx insn, basic_block bb)
6123 /* Insert at start of successor block. */
6124 rtx prev = PREV_INSN (BB_HEAD (bb));
6125 rtx before = BB_HEAD (bb);
6128 if (! LABEL_P (before)
6129 && (! NOTE_P (before)
6130 || NOTE_LINE_NUMBER (before) != NOTE_INSN_BASIC_BLOCK))
6133 if (prev == BB_END (bb))
6135 before = NEXT_INSN (before);
6138 insn = emit_insn_after_noloc (insn, prev);
6142 fprintf (dump_file, "STORE_MOTION insert store at start of BB %d:\n",
6144 print_inline_rtx (dump_file, insn, 6);
6145 fprintf (dump_file, "\n");
6149 /* This routine will insert a store on an edge. EXPR is the ldst entry for
6150 the memory reference, and E is the edge to insert it on. Returns nonzero
6151 if an edge insertion was performed. */
6154 insert_store (struct ls_expr * expr, edge e)
6161 /* We did all the deleted before this insert, so if we didn't delete a
6162 store, then we haven't set the reaching reg yet either. */
6163 if (expr->reaching_reg == NULL_RTX)
6166 if (e->flags & EDGE_FAKE)
6169 reg = expr->reaching_reg;
6170 insn = gen_move_insn (copy_rtx (expr->pattern), reg);
6172 /* If we are inserting this expression on ALL predecessor edges of a BB,
6173 insert it at the start of the BB, and reset the insert bits on the other
6174 edges so we don't try to insert it on the other edges. */
6176 FOR_EACH_EDGE (tmp, ei, e->dest->preds)
6177 if (!(tmp->flags & EDGE_FAKE))
6179 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
6181 gcc_assert (index != EDGE_INDEX_NO_EDGE);
6182 if (! TEST_BIT (pre_insert_map[index], expr->index))
6186 /* If tmp is NULL, we found an insertion on every edge, blank the
6187 insertion vector for these edges, and insert at the start of the BB. */
6188 if (!tmp && bb != EXIT_BLOCK_PTR)
6190 FOR_EACH_EDGE (tmp, ei, e->dest->preds)
6192 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
6193 RESET_BIT (pre_insert_map[index], expr->index);
6195 insert_insn_start_bb (insn, bb);
6199 /* We can't put stores in the front of blocks pointed to by abnormal
6200 edges since that may put a store where one didn't used to be. */
6201 gcc_assert (!(e->flags & EDGE_ABNORMAL));
6203 insert_insn_on_edge (insn, e);
6207 fprintf (dump_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
6208 e->src->index, e->dest->index);
6209 print_inline_rtx (dump_file, insn, 6);
6210 fprintf (dump_file, "\n");
6216 /* Remove any REG_EQUAL or REG_EQUIV notes containing a reference to the
6217 memory location in SMEXPR set in basic block BB.
6219 This could be rather expensive. */
6222 remove_reachable_equiv_notes (basic_block bb, struct ls_expr *smexpr)
6224 edge_iterator *stack, ei;
6227 sbitmap visited = sbitmap_alloc (last_basic_block);
6228 rtx last, insn, note;
6229 rtx mem = smexpr->pattern;
6231 stack = XNEWVEC (edge_iterator, n_basic_blocks);
6233 ei = ei_start (bb->succs);
6235 sbitmap_zero (visited);
6237 act = (EDGE_COUNT (ei_container (ei)) > 0 ? EDGE_I (ei_container (ei), 0) : NULL);
6245 sbitmap_free (visited);
6248 act = ei_edge (stack[--sp]);
6252 if (bb == EXIT_BLOCK_PTR
6253 || TEST_BIT (visited, bb->index))
6257 act = (! ei_end_p (ei)) ? ei_edge (ei) : NULL;
6260 SET_BIT (visited, bb->index);
6262 if (TEST_BIT (st_antloc[bb->index], smexpr->index))
6264 for (last = ANTIC_STORE_LIST (smexpr);
6265 BLOCK_FOR_INSN (XEXP (last, 0)) != bb;
6266 last = XEXP (last, 1))
6268 last = XEXP (last, 0);
6271 last = NEXT_INSN (BB_END (bb));
6273 for (insn = BB_HEAD (bb); insn != last; insn = NEXT_INSN (insn))
6276 note = find_reg_equal_equiv_note (insn);
6277 if (!note || !expr_equiv_p (XEXP (note, 0), mem))
6281 fprintf (dump_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6283 remove_note (insn, note);
6288 act = (! ei_end_p (ei)) ? ei_edge (ei) : NULL;
6290 if (EDGE_COUNT (bb->succs) > 0)
6294 ei = ei_start (bb->succs);
6295 act = (EDGE_COUNT (ei_container (ei)) > 0 ? EDGE_I (ei_container (ei), 0) : NULL);
6300 /* This routine will replace a store with a SET to a specified register. */
6303 replace_store_insn (rtx reg, rtx del, basic_block bb, struct ls_expr *smexpr)
6305 rtx insn, mem, note, set, ptr, pair;
6307 mem = smexpr->pattern;
6308 insn = gen_move_insn (reg, SET_SRC (single_set (del)));
6309 insn = emit_insn_after (insn, del);
6314 "STORE_MOTION delete insn in BB %d:\n ", bb->index);
6315 print_inline_rtx (dump_file, del, 6);
6316 fprintf (dump_file, "\nSTORE MOTION replaced with insn:\n ");
6317 print_inline_rtx (dump_file, insn, 6);
6318 fprintf (dump_file, "\n");
6321 for (ptr = ANTIC_STORE_LIST (smexpr); ptr; ptr = XEXP (ptr, 1))
6322 if (XEXP (ptr, 0) == del)
6324 XEXP (ptr, 0) = insn;
6328 /* Move the notes from the deleted insn to its replacement, and patch
6329 up the LIBCALL notes. */
6330 REG_NOTES (insn) = REG_NOTES (del);
6332 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
6335 pair = XEXP (note, 0);
6336 note = find_reg_note (pair, REG_LIBCALL, NULL_RTX);
6337 XEXP (note, 0) = insn;
6339 note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
6342 pair = XEXP (note, 0);
6343 note = find_reg_note (pair, REG_RETVAL, NULL_RTX);
6344 XEXP (note, 0) = insn;
6349 /* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
6350 they are no longer accurate provided that they are reached by this
6351 definition, so drop them. */
6352 for (; insn != NEXT_INSN (BB_END (bb)); insn = NEXT_INSN (insn))
6355 set = single_set (insn);
6358 if (expr_equiv_p (SET_DEST (set), mem))
6360 note = find_reg_equal_equiv_note (insn);
6361 if (!note || !expr_equiv_p (XEXP (note, 0), mem))
6365 fprintf (dump_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6367 remove_note (insn, note);
6369 remove_reachable_equiv_notes (bb, smexpr);
6373 /* Delete a store, but copy the value that would have been stored into
6374 the reaching_reg for later storing. */
6377 delete_store (struct ls_expr * expr, basic_block bb)
6381 if (expr->reaching_reg == NULL_RTX)
6382 expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
6384 reg = expr->reaching_reg;
6386 for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
6389 if (BLOCK_FOR_INSN (del) == bb)
6391 /* We know there is only one since we deleted redundant
6392 ones during the available computation. */
6393 replace_store_insn (reg, del, bb, expr);
6399 /* Free memory used by store motion. */
6402 free_store_memory (void)
6407 sbitmap_vector_free (ae_gen);
6409 sbitmap_vector_free (ae_kill);
6411 sbitmap_vector_free (transp);
6413 sbitmap_vector_free (st_antloc);
6415 sbitmap_vector_free (pre_insert_map);
6417 sbitmap_vector_free (pre_delete_map);
6418 if (reg_set_in_block)
6419 sbitmap_vector_free (reg_set_in_block);
6421 ae_gen = ae_kill = transp = st_antloc = NULL;
6422 pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
6425 /* Perform store motion. Much like gcse, except we move expressions the
6426 other way by looking at the flowgraph in reverse. */
6433 struct ls_expr * ptr;
6434 int update_flow = 0;
6438 fprintf (dump_file, "before store motion\n");
6439 print_rtl (dump_file, get_insns ());
6442 init_alias_analysis ();
6444 /* Find all the available and anticipatable stores. */
6445 num_stores = compute_store_table ();
6446 if (num_stores == 0)
6448 htab_delete (pre_ldst_table);
6449 pre_ldst_table = NULL;
6450 sbitmap_vector_free (reg_set_in_block);
6451 end_alias_analysis ();
6455 /* Now compute kill & transp vectors. */
6456 build_store_vectors ();
6457 add_noreturn_fake_exit_edges ();
6458 connect_infinite_loops_to_exit ();
6460 edge_list = pre_edge_rev_lcm (num_stores, transp, ae_gen,
6461 st_antloc, ae_kill, &pre_insert_map,
6464 /* Now we want to insert the new stores which are going to be needed. */
6465 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6467 /* If any of the edges we have above are abnormal, we can't move this
6469 for (x = NUM_EDGES (edge_list) - 1; x >= 0; x--)
6470 if (TEST_BIT (pre_insert_map[x], ptr->index)
6471 && (INDEX_EDGE (edge_list, x)->flags & EDGE_ABNORMAL))
6476 if (dump_file != NULL)
6478 "Can't replace store %d: abnormal edge from %d to %d\n",
6479 ptr->index, INDEX_EDGE (edge_list, x)->src->index,
6480 INDEX_EDGE (edge_list, x)->dest->index);
6484 /* Now we want to insert the new stores which are going to be needed. */
6487 if (TEST_BIT (pre_delete_map[bb->index], ptr->index))
6488 delete_store (ptr, bb);
6490 for (x = 0; x < NUM_EDGES (edge_list); x++)
6491 if (TEST_BIT (pre_insert_map[x], ptr->index))
6492 update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
6496 commit_edge_insertions ();
6498 free_store_memory ();
6499 free_edge_list (edge_list);
6500 remove_fake_exit_edges ();
6501 end_alias_analysis ();
6505 /* Entry point for jump bypassing optimization pass. */
6512 /* We do not construct an accurate cfg in functions which call
6513 setjmp, so just punt to be safe. */
6514 if (current_function_calls_setjmp)
6517 /* Identify the basic block information for this function, including
6518 successors and predecessors. */
6519 max_gcse_regno = max_reg_num ();
6522 dump_flow_info (dump_file, dump_flags);
6524 /* Return if there's nothing to do, or it is too expensive. */
6525 if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1
6526 || is_too_expensive (_ ("jump bypassing disabled")))
6529 gcc_obstack_init (&gcse_obstack);
6532 /* We need alias. */
6533 init_alias_analysis ();
6535 /* Record where pseudo-registers are set. This data is kept accurate
6536 during each pass. ??? We could also record hard-reg information here
6537 [since it's unchanging], however it is currently done during hash table
6540 It may be tempting to compute MEM set information here too, but MEM sets
6541 will be subject to code motion one day and thus we need to compute
6542 information about memory sets when we build the hash tables. */
6544 alloc_reg_set_mem (max_gcse_regno);
6547 max_gcse_regno = max_reg_num ();
6549 changed = one_cprop_pass (MAX_GCSE_PASSES + 2, true, true);
6554 fprintf (dump_file, "BYPASS of %s: %d basic blocks, ",
6555 current_function_name (), n_basic_blocks);
6556 fprintf (dump_file, "%d bytes\n\n", bytes_used);
6559 obstack_free (&gcse_obstack, NULL);
6560 free_reg_set_mem ();
6562 /* We are finished with alias. */
6563 end_alias_analysis ();
6564 allocate_reg_info (max_reg_num (), FALSE, FALSE);
6569 /* Return true if the graph is too expensive to optimize. PASS is the
6570 optimization about to be performed. */
6573 is_too_expensive (const char *pass)
6575 /* Trying to perform global optimizations on flow graphs which have
6576 a high connectivity will take a long time and is unlikely to be
6577 particularly useful.
6579 In normal circumstances a cfg should have about twice as many
6580 edges as blocks. But we do not want to punish small functions
6581 which have a couple switch statements. Rather than simply
6582 threshold the number of blocks, uses something with a more
6583 graceful degradation. */
6584 if (n_edges > 20000 + n_basic_blocks * 4)
6586 warning (OPT_Wdisabled_optimization,
6587 "%s: %d basic blocks and %d edges/basic block",
6588 pass, n_basic_blocks, n_edges / n_basic_blocks);
6593 /* If allocating memory for the cprop bitmap would take up too much
6594 storage it's better just to disable the optimization. */
6596 * SBITMAP_SET_SIZE (max_reg_num ())
6597 * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
6599 warning (OPT_Wdisabled_optimization,
6600 "%s: %d basic blocks and %d registers",
6601 pass, n_basic_blocks, max_reg_num ());
6610 gate_handle_jump_bypass (void)
6612 return optimize > 0 && flag_gcse;
6615 /* Perform jump bypassing and control flow optimizations. */
6617 rest_of_handle_jump_bypass (void)
6619 cleanup_cfg (CLEANUP_EXPENSIVE);
6620 reg_scan (get_insns (), max_reg_num ());
6622 if (bypass_jumps ())
6624 rebuild_jump_labels (get_insns ());
6625 cleanup_cfg (CLEANUP_EXPENSIVE);
6626 delete_trivially_dead_insns (get_insns (), max_reg_num ());
6630 struct tree_opt_pass pass_jump_bypass =
6632 "bypass", /* name */
6633 gate_handle_jump_bypass, /* gate */
6634 rest_of_handle_jump_bypass, /* execute */
6637 0, /* static_pass_number */
6638 TV_BYPASS, /* tv_id */
6639 0, /* properties_required */
6640 0, /* properties_provided */
6641 0, /* properties_destroyed */
6642 0, /* todo_flags_start */
6644 TODO_ggc_collect | TODO_verify_flow, /* todo_flags_finish */
6650 gate_handle_gcse (void)
6652 return optimize > 0 && flag_gcse;
6657 rest_of_handle_gcse (void)
6659 int save_csb, save_cfj;
6662 tem = gcse_main (get_insns ());
6663 rebuild_jump_labels (get_insns ());
6664 delete_trivially_dead_insns (get_insns (), max_reg_num ());
6666 save_csb = flag_cse_skip_blocks;
6667 save_cfj = flag_cse_follow_jumps;
6668 flag_cse_skip_blocks = flag_cse_follow_jumps = 0;
6670 /* If -fexpensive-optimizations, re-run CSE to clean up things done
6672 if (flag_expensive_optimizations)
6674 timevar_push (TV_CSE);
6675 reg_scan (get_insns (), max_reg_num ());
6676 tem2 = cse_main (get_insns (), max_reg_num ());
6677 purge_all_dead_edges ();
6678 delete_trivially_dead_insns (get_insns (), max_reg_num ());
6679 timevar_pop (TV_CSE);
6680 cse_not_expected = !flag_rerun_cse_after_loop;
6683 /* If gcse or cse altered any jumps, rerun jump optimizations to clean
6687 timevar_push (TV_JUMP);
6688 rebuild_jump_labels (get_insns ());
6689 delete_dead_jumptables ();
6690 cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_PRE_LOOP);
6691 timevar_pop (TV_JUMP);
6694 flag_cse_skip_blocks = save_csb;
6695 flag_cse_follow_jumps = save_cfj;
6698 struct tree_opt_pass pass_gcse =
6701 gate_handle_gcse, /* gate */
6702 rest_of_handle_gcse, /* execute */
6705 0, /* static_pass_number */
6706 TV_GCSE, /* tv_id */
6707 0, /* properties_required */
6708 0, /* properties_provided */
6709 0, /* properties_destroyed */
6710 0, /* todo_flags_start */
6712 TODO_verify_flow | TODO_ggc_collect, /* todo_flags_finish */
6717 #include "gt-gcse.h"