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 2006, 2007 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 3, 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 COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
23 - reordering of memory allocation and freeing to be more space efficient
24 - do rough calc of how many regs are needed in each block, and a rough
25 calc of how many regs are available in each class and use that to
26 throttle back the code in cases where RTX_COST is minimal.
27 - a store to the same address as a load does not kill the load if the
28 source of the store is also the destination of the load. Handling this
29 allows more load motion, particularly out of loops.
30 - ability to realloc sbitmap vectors would allow one initial computation
31 of reg_set_in_block with only subsequent additions, rather than
32 recomputing it for each pass
36 /* References searched while implementing this.
38 Compilers Principles, Techniques and Tools
42 Global Optimization by Suppression of Partial Redundancies
44 communications of the acm, Vol. 22, Num. 2, Feb. 1979
46 A Portable Machine-Independent Global Optimizer - Design and Measurements
48 Stanford Ph.D. thesis, Dec. 1983
50 A Fast Algorithm for Code Movement Optimization
52 SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988
54 A Solution to a Problem with Morel and Renvoise's
55 Global Optimization by Suppression of Partial Redundancies
56 K-H Drechsler, M.P. Stadel
57 ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988
59 Practical Adaptation of the Global Optimization
60 Algorithm of Morel and Renvoise
62 ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991
64 Efficiently Computing Static Single Assignment Form and the Control
66 R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck
67 ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991
70 J. Knoop, O. Ruthing, B. Steffen
71 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
73 What's In a Region? Or Computing Control Dependence Regions in Near-Linear
74 Time for Reducible Flow Control
76 ACM Letters on Programming Languages and Systems,
77 Vol. 2, Num. 1-4, Mar-Dec 1993
79 An Efficient Representation for Sparse Sets
80 Preston Briggs, Linda Torczon
81 ACM Letters on Programming Languages and Systems,
82 Vol. 2, Num. 1-4, Mar-Dec 1993
84 A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion
85 K-H Drechsler, M.P. Stadel
86 ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993
88 Partial Dead Code Elimination
89 J. Knoop, O. Ruthing, B. Steffen
90 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
92 Effective Partial Redundancy Elimination
93 P. Briggs, K.D. Cooper
94 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
96 The Program Structure Tree: Computing Control Regions in Linear Time
97 R. Johnson, D. Pearson, K. Pingali
98 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
100 Optimal Code Motion: Theory and Practice
101 J. Knoop, O. Ruthing, B. Steffen
102 ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994
104 The power of assignment motion
105 J. Knoop, O. Ruthing, B. Steffen
106 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
108 Global code motion / global value numbering
110 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
112 Value Driven Redundancy Elimination
114 Rice University Ph.D. thesis, Apr. 1996
118 Massively Scalar Compiler Project, Rice University, Sep. 1996
120 High Performance Compilers for Parallel Computing
124 Advanced Compiler Design and Implementation
126 Morgan Kaufmann, 1997
128 Building an Optimizing Compiler
132 People wishing to speed up the code here should read:
133 Elimination Algorithms for Data Flow Analysis
134 B.G. Ryder, M.C. Paull
135 ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986
137 How to Analyze Large Programs Efficiently and Informatively
138 D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck
139 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
141 People wishing to do something different can find various possibilities
142 in the above papers and elsewhere.
147 #include "coretypes.h"
155 #include "hard-reg-set.h"
158 #include "insn-config.h"
160 #include "basic-block.h"
162 #include "function.h"
171 #include "tree-pass.h"
176 /* Propagate flow information through back edges and thus enable PRE's
177 moving loop invariant calculations out of loops.
179 Originally this tended to create worse overall code, but several
180 improvements during the development of PRE seem to have made following
181 back edges generally a win.
183 Note much of the loop invariant code motion done here would normally
184 be done by loop.c, which has more heuristics for when to move invariants
185 out of loops. At some point we might need to move some of those
186 heuristics into gcse.c. */
188 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
189 are a superset of those done by GCSE.
191 We perform the following steps:
193 1) Compute basic block information.
195 2) Compute table of places where registers are set.
197 3) Perform copy/constant propagation.
199 4) Perform global cse using lazy code motion if not optimizing
200 for size, or code hoisting if we are.
202 5) Perform another pass of copy/constant propagation.
204 Two passes of copy/constant propagation are done because the first one
205 enables more GCSE and the second one helps to clean up the copies that
206 GCSE creates. This is needed more for PRE than for Classic because Classic
207 GCSE will try to use an existing register containing the common
208 subexpression rather than create a new one. This is harder to do for PRE
209 because of the code motion (which Classic GCSE doesn't do).
211 Expressions we are interested in GCSE-ing are of the form
212 (set (pseudo-reg) (expression)).
213 Function want_to_gcse_p says what these are.
215 PRE handles moving invariant expressions out of loops (by treating them as
216 partially redundant).
218 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
219 assignment) based GVN (global value numbering). L. T. Simpson's paper
220 (Rice University) on value numbering is a useful reference for this.
222 **********************
224 We used to support multiple passes but there are diminishing returns in
225 doing so. The first pass usually makes 90% of the changes that are doable.
226 A second pass can make a few more changes made possible by the first pass.
227 Experiments show any further passes don't make enough changes to justify
230 A study of spec92 using an unlimited number of passes:
231 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
232 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
233 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
235 It was found doing copy propagation between each pass enables further
238 PRE is quite expensive in complicated functions because the DFA can take
239 a while to converge. Hence we only perform one pass. The parameter
240 max-gcse-passes can be modified if one wants to experiment.
242 **********************
244 The steps for PRE are:
246 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
248 2) Perform the data flow analysis for PRE.
250 3) Delete the redundant instructions
252 4) Insert the required copies [if any] that make the partially
253 redundant instructions fully redundant.
255 5) For other reaching expressions, insert an instruction to copy the value
256 to a newly created pseudo that will reach the redundant instruction.
258 The deletion is done first so that when we do insertions we
259 know which pseudo reg to use.
261 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
262 argue it is not. The number of iterations for the algorithm to converge
263 is typically 2-4 so I don't view it as that expensive (relatively speaking).
265 PRE GCSE depends heavily on the second CSE pass to clean up the copies
266 we create. To make an expression reach the place where it's redundant,
267 the result of the expression is copied to a new register, and the redundant
268 expression is deleted by replacing it with this new register. Classic GCSE
269 doesn't have this problem as much as it computes the reaching defs of
270 each register in each block and thus can try to use an existing
273 /* GCSE global vars. */
275 /* Note whether or not we should run jump optimization after gcse. We
276 want to do this for two cases.
278 * If we changed any jumps via cprop.
280 * If we added any labels via edge splitting. */
281 static int run_jump_opt_after_gcse;
283 /* An obstack for our working variables. */
284 static struct obstack gcse_obstack;
286 struct reg_use {rtx reg_rtx; };
288 /* Hash table of expressions. */
292 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
294 /* Index in the available expression bitmaps. */
296 /* Next entry with the same hash. */
297 struct expr *next_same_hash;
298 /* List of anticipatable occurrences in basic blocks in the function.
299 An "anticipatable occurrence" is one that is the first occurrence in the
300 basic block, the operands are not modified in the basic block prior
301 to the occurrence and the output is not used between the start of
302 the block and the occurrence. */
303 struct occr *antic_occr;
304 /* List of available occurrence in basic blocks in the function.
305 An "available occurrence" is one that is the last occurrence in the
306 basic block and the operands are not modified by following statements in
307 the basic block [including this insn]. */
308 struct occr *avail_occr;
309 /* Non-null if the computation is PRE redundant.
310 The value is the newly created pseudo-reg to record a copy of the
311 expression in all the places that reach the redundant copy. */
315 /* Occurrence of an expression.
316 There is one per basic block. If a pattern appears more than once the
317 last appearance is used [or first for anticipatable expressions]. */
321 /* Next occurrence of this expression. */
323 /* The insn that computes the expression. */
325 /* Nonzero if this [anticipatable] occurrence has been deleted. */
327 /* Nonzero if this [available] occurrence has been copied to
329 /* ??? This is mutually exclusive with deleted_p, so they could share
334 /* Expression and copy propagation hash tables.
335 Each hash table is an array of buckets.
336 ??? It is known that if it were an array of entries, structure elements
337 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
338 not clear whether in the final analysis a sufficient amount of memory would
339 be saved as the size of the available expression bitmaps would be larger
340 [one could build a mapping table without holes afterwards though].
341 Someday I'll perform the computation and figure it out. */
346 This is an array of `expr_hash_table_size' elements. */
349 /* Size of the hash table, in elements. */
352 /* Number of hash table elements. */
353 unsigned int n_elems;
355 /* Whether the table is expression of copy propagation one. */
359 /* Expression hash table. */
360 static struct hash_table expr_hash_table;
362 /* Copy propagation hash table. */
363 static struct hash_table set_hash_table;
365 /* Mapping of uids to cuids.
366 Only real insns get cuids. */
367 static int *uid_cuid;
369 /* Highest UID in UID_CUID. */
372 /* Get the cuid of an insn. */
373 #ifdef ENABLE_CHECKING
374 #define INSN_CUID(INSN) \
375 (gcc_assert (INSN_UID (INSN) <= max_uid), uid_cuid[INSN_UID (INSN)])
377 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
380 /* Number of cuids. */
383 /* Mapping of cuids to insns. */
384 static rtx *cuid_insn;
386 /* Get insn from cuid. */
387 #define CUID_INSN(CUID) (cuid_insn[CUID])
389 /* Maximum register number in function prior to doing gcse + 1.
390 Registers created during this pass have regno >= max_gcse_regno.
391 This is named with "gcse" to not collide with global of same name. */
392 static unsigned int max_gcse_regno;
394 /* Table of registers that are modified.
396 For each register, each element is a list of places where the pseudo-reg
399 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
400 requires knowledge of which blocks kill which regs [and thus could use
401 a bitmap instead of the lists `reg_set_table' uses].
403 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
404 num-regs) [however perhaps it may be useful to keep the data as is]. One
405 advantage of recording things this way is that `reg_set_table' is fairly
406 sparse with respect to pseudo regs but for hard regs could be fairly dense
407 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
408 up functions like compute_transp since in the case of pseudo-regs we only
409 need to iterate over the number of times a pseudo-reg is set, not over the
410 number of basic blocks [clearly there is a bit of a slow down in the cases
411 where a pseudo is set more than once in a block, however it is believed
412 that the net effect is to speed things up]. This isn't done for hard-regs
413 because recording call-clobbered hard-regs in `reg_set_table' at each
414 function call can consume a fair bit of memory, and iterating over
415 hard-regs stored this way in compute_transp will be more expensive. */
417 typedef struct reg_set
419 /* The next setting of this register. */
420 struct reg_set *next;
421 /* The index of the block where it was set. */
425 static reg_set **reg_set_table;
427 /* Size of `reg_set_table'.
428 The table starts out at max_gcse_regno + slop, and is enlarged as
430 static int reg_set_table_size;
432 /* Amount to grow `reg_set_table' by when it's full. */
433 #define REG_SET_TABLE_SLOP 100
435 /* This is a list of expressions which are MEMs and will be used by load
437 Load motion tracks MEMs which aren't killed by
438 anything except itself. (i.e., loads and stores to a single location).
439 We can then allow movement of these MEM refs with a little special
440 allowance. (all stores copy the same value to the reaching reg used
441 for the loads). This means all values used to store into memory must have
442 no side effects so we can re-issue the setter value.
443 Store Motion uses this structure as an expression table to track stores
444 which look interesting, and might be moveable towards the exit block. */
448 struct expr * expr; /* Gcse expression reference for LM. */
449 rtx pattern; /* Pattern of this mem. */
450 rtx pattern_regs; /* List of registers mentioned by the mem. */
451 rtx loads; /* INSN list of loads seen. */
452 rtx stores; /* INSN list of stores seen. */
453 struct ls_expr * next; /* Next in the list. */
454 int invalid; /* Invalid for some reason. */
455 int index; /* If it maps to a bitmap index. */
456 unsigned int hash_index; /* Index when in a hash table. */
457 rtx reaching_reg; /* Register to use when re-writing. */
460 /* Array of implicit set patterns indexed by basic block index. */
461 static rtx *implicit_sets;
463 /* Head of the list of load/store memory refs. */
464 static struct ls_expr * pre_ldst_mems = NULL;
466 /* Hashtable for the load/store memory refs. */
467 static htab_t pre_ldst_table = NULL;
469 /* Bitmap containing one bit for each register in the program.
470 Used when performing GCSE to track which registers have been set since
471 the start of the basic block. */
472 static regset reg_set_bitmap;
474 /* For each block, a bitmap of registers set in the block.
475 This is used by compute_transp.
476 It is computed during hash table computation and not by compute_sets
477 as it includes registers added since the last pass (or between cprop and
478 gcse) and it's currently not easy to realloc sbitmap vectors. */
479 static sbitmap *reg_set_in_block;
481 /* Array, indexed by basic block number for a list of insns which modify
482 memory within that block. */
483 static rtx * modify_mem_list;
484 static bitmap modify_mem_list_set;
486 /* This array parallels modify_mem_list, but is kept canonicalized. */
487 static rtx * canon_modify_mem_list;
489 /* Bitmap indexed by block numbers to record which blocks contain
491 static bitmap blocks_with_calls;
493 /* Various variables for statistics gathering. */
495 /* Memory used in a pass.
496 This isn't intended to be absolutely precise. Its intent is only
497 to keep an eye on memory usage. */
498 static int bytes_used;
500 /* GCSE substitutions made. */
501 static int gcse_subst_count;
502 /* Number of copy instructions created. */
503 static int gcse_create_count;
504 /* Number of local constants propagated. */
505 static int local_const_prop_count;
506 /* Number of local copies propagated. */
507 static int local_copy_prop_count;
508 /* Number of global constants propagated. */
509 static int global_const_prop_count;
510 /* Number of global copies propagated. */
511 static int global_copy_prop_count;
513 /* For available exprs */
514 static sbitmap *ae_kill, *ae_gen;
516 static void compute_can_copy (void);
517 static void *gmalloc (size_t) ATTRIBUTE_MALLOC;
518 static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC;
519 static void *grealloc (void *, size_t);
520 static void *gcse_alloc (unsigned long);
521 static void alloc_gcse_mem (void);
522 static void free_gcse_mem (void);
523 static void alloc_reg_set_mem (int);
524 static void free_reg_set_mem (void);
525 static void record_one_set (int, rtx);
526 static void record_set_info (rtx, const_rtx, void *);
527 static void compute_sets (void);
528 static void hash_scan_insn (rtx, struct hash_table *, int);
529 static void hash_scan_set (rtx, rtx, struct hash_table *);
530 static void hash_scan_clobber (rtx, rtx, struct hash_table *);
531 static void hash_scan_call (rtx, rtx, struct hash_table *);
532 static int want_to_gcse_p (rtx);
533 static bool can_assign_to_reg_p (rtx);
534 static bool gcse_constant_p (const_rtx);
535 static int oprs_unchanged_p (const_rtx, const_rtx, int);
536 static int oprs_anticipatable_p (const_rtx, const_rtx);
537 static int oprs_available_p (const_rtx, const_rtx);
538 static void insert_expr_in_table (rtx, enum machine_mode, rtx, int, int,
539 struct hash_table *);
540 static void insert_set_in_table (rtx, rtx, struct hash_table *);
541 static unsigned int hash_expr (const_rtx, enum machine_mode, int *, int);
542 static unsigned int hash_set (int, int);
543 static int expr_equiv_p (const_rtx, const_rtx);
544 static void record_last_reg_set_info (rtx, int);
545 static void record_last_mem_set_info (rtx);
546 static void record_last_set_info (rtx, const_rtx, void *);
547 static void compute_hash_table (struct hash_table *);
548 static void alloc_hash_table (int, struct hash_table *, int);
549 static void free_hash_table (struct hash_table *);
550 static void compute_hash_table_work (struct hash_table *);
551 static void dump_hash_table (FILE *, const char *, struct hash_table *);
552 static struct expr *lookup_set (unsigned int, struct hash_table *);
553 static struct expr *next_set (unsigned int, struct expr *);
554 static void reset_opr_set_tables (void);
555 static int oprs_not_set_p (const_rtx, const_rtx);
556 static void mark_call (rtx);
557 static void mark_set (rtx, rtx);
558 static void mark_clobber (rtx, rtx);
559 static void mark_oprs_set (rtx);
560 static void alloc_cprop_mem (int, int);
561 static void free_cprop_mem (void);
562 static void compute_transp (const_rtx, int, sbitmap *, int);
563 static void compute_transpout (void);
564 static void compute_local_properties (sbitmap *, sbitmap *, sbitmap *,
565 struct hash_table *);
566 static void compute_cprop_data (void);
567 static void find_used_regs (rtx *, void *);
568 static int try_replace_reg (rtx, rtx, rtx);
569 static struct expr *find_avail_set (int, rtx);
570 static int cprop_jump (basic_block, rtx, rtx, rtx, rtx);
571 static void mems_conflict_for_gcse_p (rtx, const_rtx, void *);
572 static int load_killed_in_block_p (const_basic_block, int, const_rtx, int);
573 static void canon_list_insert (rtx, const_rtx, void *);
574 static int cprop_insn (rtx, int);
575 static int cprop (int);
576 static void find_implicit_sets (void);
577 static int one_cprop_pass (int, bool, bool);
578 static bool constprop_register (rtx, rtx, rtx, bool);
579 static struct expr *find_bypass_set (int, int);
580 static bool reg_killed_on_edge (const_rtx, const_edge);
581 static int bypass_block (basic_block, rtx, rtx);
582 static int bypass_conditional_jumps (void);
583 static void alloc_pre_mem (int, int);
584 static void free_pre_mem (void);
585 static void compute_pre_data (void);
586 static int pre_expr_reaches_here_p (basic_block, struct expr *,
588 static void insert_insn_end_basic_block (struct expr *, basic_block, int);
589 static void pre_insert_copy_insn (struct expr *, rtx);
590 static void pre_insert_copies (void);
591 static int pre_delete (void);
592 static int pre_gcse (void);
593 static int one_pre_gcse_pass (int);
594 static void add_label_notes (rtx, rtx);
595 static void alloc_code_hoist_mem (int, int);
596 static void free_code_hoist_mem (void);
597 static void compute_code_hoist_vbeinout (void);
598 static void compute_code_hoist_data (void);
599 static int hoist_expr_reaches_here_p (basic_block, int, basic_block, char *);
600 static void hoist_code (void);
601 static int one_code_hoisting_pass (void);
602 static rtx process_insert_insn (struct expr *);
603 static int pre_edge_insert (struct edge_list *, struct expr **);
604 static int pre_expr_reaches_here_p_work (basic_block, struct expr *,
605 basic_block, char *);
606 static struct ls_expr * ldst_entry (rtx);
607 static void free_ldst_entry (struct ls_expr *);
608 static void free_ldst_mems (void);
609 static void print_ldst_list (FILE *);
610 static struct ls_expr * find_rtx_in_ldst (rtx);
611 static int enumerate_ldsts (void);
612 static inline struct ls_expr * first_ls_expr (void);
613 static inline struct ls_expr * next_ls_expr (struct ls_expr *);
614 static int simple_mem (const_rtx);
615 static void invalidate_any_buried_refs (rtx);
616 static void compute_ld_motion_mems (void);
617 static void trim_ld_motion_mems (void);
618 static void update_ld_motion_stores (struct expr *);
619 static void reg_set_info (rtx, const_rtx, void *);
620 static void reg_clear_last_set (rtx, const_rtx, void *);
621 static bool store_ops_ok (const_rtx, int *);
622 static rtx extract_mentioned_regs (rtx);
623 static rtx extract_mentioned_regs_helper (rtx, rtx);
624 static void find_moveable_store (rtx, int *, int *);
625 static int compute_store_table (void);
626 static bool load_kills_store (const_rtx, const_rtx, int);
627 static bool find_loads (const_rtx, const_rtx, int);
628 static bool store_killed_in_insn (const_rtx, const_rtx, const_rtx, int);
629 static bool store_killed_after (const_rtx, const_rtx, const_rtx, const_basic_block, int *, rtx *);
630 static bool store_killed_before (const_rtx, const_rtx, const_rtx, const_basic_block, int *);
631 static void build_store_vectors (void);
632 static void insert_insn_start_basic_block (rtx, basic_block);
633 static int insert_store (struct ls_expr *, edge);
634 static void remove_reachable_equiv_notes (basic_block, struct ls_expr *);
635 static void replace_store_insn (rtx, rtx, basic_block, struct ls_expr *);
636 static void delete_store (struct ls_expr *, basic_block);
637 static void free_store_memory (void);
638 static void store_motion (void);
639 static void free_insn_expr_list_list (rtx *);
640 static void clear_modify_mem_tables (void);
641 static void free_modify_mem_tables (void);
642 static rtx gcse_emit_move_after (rtx, rtx, rtx);
643 static void local_cprop_find_used_regs (rtx *, void *);
644 static bool do_local_cprop (rtx, rtx, bool, rtx*);
645 static bool adjust_libcall_notes (rtx, rtx, rtx, rtx*);
646 static void local_cprop_pass (bool);
647 static bool is_too_expensive (const char *);
650 /* Entry point for global common subexpression elimination.
651 F is the first instruction in the function. Return nonzero if a
655 gcse_main (rtx f ATTRIBUTE_UNUSED)
658 /* Bytes used at start of pass. */
659 int initial_bytes_used;
660 /* Maximum number of bytes used by a pass. */
662 /* Point to release obstack data from for each pass. */
663 char *gcse_obstack_bottom;
665 /* We do not construct an accurate cfg in functions which call
666 setjmp, so just punt to be safe. */
667 if (current_function_calls_setjmp)
670 /* Assume that we do not need to run jump optimizations after gcse. */
671 run_jump_opt_after_gcse = 0;
673 /* Identify the basic block information for this function, including
674 successors and predecessors. */
675 max_gcse_regno = max_reg_num ();
677 df_note_add_problem ();
681 dump_flow_info (dump_file, dump_flags);
683 /* Return if there's nothing to do, or it is too expensive. */
684 if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1
685 || is_too_expensive (_("GCSE disabled")))
688 gcc_obstack_init (&gcse_obstack);
692 init_alias_analysis ();
693 /* Record where pseudo-registers are set. This data is kept accurate
694 during each pass. ??? We could also record hard-reg information here
695 [since it's unchanging], however it is currently done during hash table
698 It may be tempting to compute MEM set information here too, but MEM sets
699 will be subject to code motion one day and thus we need to compute
700 information about memory sets when we build the hash tables. */
702 alloc_reg_set_mem (max_gcse_regno);
706 initial_bytes_used = bytes_used;
708 gcse_obstack_bottom = gcse_alloc (1);
710 while (changed && pass < MAX_GCSE_PASSES)
714 fprintf (dump_file, "GCSE pass %d\n\n", pass + 1);
716 /* Initialize bytes_used to the space for the pred/succ lists,
717 and the reg_set_table data. */
718 bytes_used = initial_bytes_used;
720 /* Each pass may create new registers, so recalculate each time. */
721 max_gcse_regno = max_reg_num ();
725 /* Don't allow constant propagation to modify jumps
727 timevar_push (TV_CPROP1);
728 changed = one_cprop_pass (pass + 1, false, false);
729 timevar_pop (TV_CPROP1);
735 timevar_push (TV_PRE);
736 changed |= one_pre_gcse_pass (pass + 1);
737 /* We may have just created new basic blocks. Release and
738 recompute various things which are sized on the number of
742 free_modify_mem_tables ();
743 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
744 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
747 alloc_reg_set_mem (max_reg_num ());
749 run_jump_opt_after_gcse = 1;
750 timevar_pop (TV_PRE);
753 if (max_pass_bytes < bytes_used)
754 max_pass_bytes = bytes_used;
756 /* Free up memory, then reallocate for code hoisting. We can
757 not re-use the existing allocated memory because the tables
758 will not have info for the insns or registers created by
759 partial redundancy elimination. */
762 /* It does not make sense to run code hoisting unless we are optimizing
763 for code size -- it rarely makes programs faster, and can make
764 them bigger if we did partial redundancy elimination (when optimizing
765 for space, we don't run the partial redundancy algorithms). */
768 timevar_push (TV_HOIST);
769 max_gcse_regno = max_reg_num ();
771 changed |= one_code_hoisting_pass ();
774 if (max_pass_bytes < bytes_used)
775 max_pass_bytes = bytes_used;
776 timevar_pop (TV_HOIST);
781 fprintf (dump_file, "\n");
785 obstack_free (&gcse_obstack, gcse_obstack_bottom);
789 /* Do one last pass of copy propagation, including cprop into
790 conditional jumps. */
792 max_gcse_regno = max_reg_num ();
794 /* This time, go ahead and allow cprop to alter jumps. */
795 timevar_push (TV_CPROP2);
796 one_cprop_pass (pass + 1, true, true);
797 timevar_pop (TV_CPROP2);
802 fprintf (dump_file, "GCSE of %s: %d basic blocks, ",
803 current_function_name (), n_basic_blocks);
804 fprintf (dump_file, "%d pass%s, %d bytes\n\n",
805 pass, pass > 1 ? "es" : "", max_pass_bytes);
808 obstack_free (&gcse_obstack, NULL);
811 /* We are finished with alias. */
812 end_alias_analysis ();
814 if (!optimize_size && flag_gcse_sm)
816 timevar_push (TV_LSM);
818 timevar_pop (TV_LSM);
821 /* Record where pseudo-registers are set. */
822 return run_jump_opt_after_gcse;
825 /* Misc. utilities. */
827 /* Nonzero for each mode that supports (set (reg) (reg)).
828 This is trivially true for integer and floating point values.
829 It may or may not be true for condition codes. */
830 static char can_copy[(int) NUM_MACHINE_MODES];
832 /* Compute which modes support reg/reg copy operations. */
835 compute_can_copy (void)
838 #ifndef AVOID_CCMODE_COPIES
841 memset (can_copy, 0, NUM_MACHINE_MODES);
844 for (i = 0; i < NUM_MACHINE_MODES; i++)
845 if (GET_MODE_CLASS (i) == MODE_CC)
847 #ifdef AVOID_CCMODE_COPIES
850 reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1);
851 insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
852 if (recog (PATTERN (insn), insn, NULL) >= 0)
862 /* Returns whether the mode supports reg/reg copy operations. */
865 can_copy_p (enum machine_mode mode)
867 static bool can_copy_init_p = false;
869 if (! can_copy_init_p)
872 can_copy_init_p = true;
875 return can_copy[mode] != 0;
878 /* Cover function to xmalloc to record bytes allocated. */
881 gmalloc (size_t size)
884 return xmalloc (size);
887 /* Cover function to xcalloc to record bytes allocated. */
890 gcalloc (size_t nelem, size_t elsize)
892 bytes_used += nelem * elsize;
893 return xcalloc (nelem, elsize);
896 /* Cover function to xrealloc.
897 We don't record the additional size since we don't know it.
898 It won't affect memory usage stats much anyway. */
901 grealloc (void *ptr, size_t size)
903 return xrealloc (ptr, size);
906 /* Cover function to obstack_alloc. */
909 gcse_alloc (unsigned long size)
912 return obstack_alloc (&gcse_obstack, size);
915 /* Allocate memory for the cuid mapping array,
916 and reg/memory set tracking tables.
918 This is called at the start of each pass. */
921 alloc_gcse_mem (void)
927 /* Find the largest UID and create a mapping from UIDs to CUIDs.
928 CUIDs are like UIDs except they increase monotonically, have no gaps,
929 and only apply to real insns.
930 (Actually, there are gaps, for insn that are not inside a basic block.
931 but we should never see those anyway, so this is OK.) */
933 max_uid = get_max_uid ();
934 uid_cuid = gcalloc (max_uid + 1, sizeof (int));
937 FOR_BB_INSNS (bb, insn)
940 uid_cuid[INSN_UID (insn)] = i++;
942 uid_cuid[INSN_UID (insn)] = i;
945 /* Create a table mapping cuids to insns. */
948 cuid_insn = gcalloc (max_cuid + 1, sizeof (rtx));
951 FOR_BB_INSNS (bb, insn)
953 CUID_INSN (i++) = insn;
955 /* Allocate vars to track sets of regs. */
956 reg_set_bitmap = BITMAP_ALLOC (NULL);
958 /* Allocate vars to track sets of regs, memory per block. */
959 reg_set_in_block = sbitmap_vector_alloc (last_basic_block, max_gcse_regno);
960 /* Allocate array to keep a list of insns which modify memory in each
962 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
963 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
964 modify_mem_list_set = BITMAP_ALLOC (NULL);
965 blocks_with_calls = BITMAP_ALLOC (NULL);
968 /* Free memory allocated by alloc_gcse_mem. */
976 BITMAP_FREE (reg_set_bitmap);
978 sbitmap_vector_free (reg_set_in_block);
979 free_modify_mem_tables ();
980 BITMAP_FREE (modify_mem_list_set);
981 BITMAP_FREE (blocks_with_calls);
984 /* Compute the local properties of each recorded expression.
986 Local properties are those that are defined by the block, irrespective of
989 An expression is transparent in a block if its operands are not modified
992 An expression is computed (locally available) in a block if it is computed
993 at least once and expression would contain the same value if the
994 computation was moved to the end of the block.
996 An expression is locally anticipatable in a block if it is computed at
997 least once and expression would contain the same value if the computation
998 was moved to the beginning of the block.
1000 We call this routine for cprop, pre and code hoisting. They all compute
1001 basically the same information and thus can easily share this code.
1003 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1004 properties. If NULL, then it is not necessary to compute or record that
1005 particular property.
1007 TABLE controls which hash table to look at. If it is set hash table,
1008 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1012 compute_local_properties (sbitmap *transp, sbitmap *comp, sbitmap *antloc,
1013 struct hash_table *table)
1017 /* Initialize any bitmaps that were passed in. */
1021 sbitmap_vector_zero (transp, last_basic_block);
1023 sbitmap_vector_ones (transp, last_basic_block);
1027 sbitmap_vector_zero (comp, last_basic_block);
1029 sbitmap_vector_zero (antloc, last_basic_block);
1031 for (i = 0; i < table->size; i++)
1035 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
1037 int indx = expr->bitmap_index;
1040 /* The expression is transparent in this block if it is not killed.
1041 We start by assuming all are transparent [none are killed], and
1042 then reset the bits for those that are. */
1044 compute_transp (expr->expr, indx, transp, table->set_p);
1046 /* The occurrences recorded in antic_occr are exactly those that
1047 we want to set to nonzero in ANTLOC. */
1049 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
1051 SET_BIT (antloc[BLOCK_NUM (occr->insn)], indx);
1053 /* While we're scanning the table, this is a good place to
1055 occr->deleted_p = 0;
1058 /* The occurrences recorded in avail_occr are exactly those that
1059 we want to set to nonzero in COMP. */
1061 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
1063 SET_BIT (comp[BLOCK_NUM (occr->insn)], indx);
1065 /* While we're scanning the table, this is a good place to
1070 /* While we're scanning the table, this is a good place to
1072 expr->reaching_reg = 0;
1077 /* Register set information.
1079 `reg_set_table' records where each register is set or otherwise
1082 static struct obstack reg_set_obstack;
1085 alloc_reg_set_mem (int n_regs)
1087 reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
1088 reg_set_table = gcalloc (reg_set_table_size, sizeof (struct reg_set *));
1090 gcc_obstack_init (®_set_obstack);
1094 free_reg_set_mem (void)
1096 free (reg_set_table);
1097 obstack_free (®_set_obstack, NULL);
1100 /* Record REGNO in the reg_set table. */
1103 record_one_set (int regno, rtx insn)
1105 /* Allocate a new reg_set element and link it onto the list. */
1106 struct reg_set *new_reg_info;
1108 /* If the table isn't big enough, enlarge it. */
1109 if (regno >= reg_set_table_size)
1111 int new_size = regno + REG_SET_TABLE_SLOP;
1113 reg_set_table = grealloc (reg_set_table,
1114 new_size * sizeof (struct reg_set *));
1115 memset (reg_set_table + reg_set_table_size, 0,
1116 (new_size - reg_set_table_size) * sizeof (struct reg_set *));
1117 reg_set_table_size = new_size;
1120 new_reg_info = obstack_alloc (®_set_obstack, sizeof (struct reg_set));
1121 bytes_used += sizeof (struct reg_set);
1122 new_reg_info->bb_index = BLOCK_NUM (insn);
1123 new_reg_info->next = reg_set_table[regno];
1124 reg_set_table[regno] = new_reg_info;
1127 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1128 an insn. The DATA is really the instruction in which the SET is
1132 record_set_info (rtx dest, const_rtx setter ATTRIBUTE_UNUSED, void *data)
1134 rtx record_set_insn = (rtx) data;
1136 if (REG_P (dest) && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
1137 record_one_set (REGNO (dest), record_set_insn);
1140 /* Scan the function and record each set of each pseudo-register.
1142 This is called once, at the start of the gcse pass. See the comments for
1143 `reg_set_table' for further documentation. */
1152 FOR_BB_INSNS (bb, insn)
1154 note_stores (PATTERN (insn), record_set_info, insn);
1157 /* Hash table support. */
1159 struct reg_avail_info
1161 basic_block last_bb;
1166 static struct reg_avail_info *reg_avail_info;
1167 static basic_block current_bb;
1170 /* See whether X, the source of a set, is something we want to consider for
1174 want_to_gcse_p (rtx x)
1177 /* On register stack architectures, don't GCSE constants from the
1178 constant pool, as the benefits are often swamped by the overhead
1179 of shuffling the register stack between basic blocks. */
1180 if (IS_STACK_MODE (GET_MODE (x)))
1181 x = avoid_constant_pool_reference (x);
1184 switch (GET_CODE (x))
1196 return can_assign_to_reg_p (x);
1200 /* Used internally by can_assign_to_reg_p. */
1202 static GTY(()) rtx test_insn;
1204 /* Return true if we can assign X to a pseudo register. */
1207 can_assign_to_reg_p (rtx x)
1209 int num_clobbers = 0;
1212 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1213 if (general_operand (x, GET_MODE (x)))
1215 else if (GET_MODE (x) == VOIDmode)
1218 /* Otherwise, check if we can make a valid insn from it. First initialize
1219 our test insn if we haven't already. */
1223 = make_insn_raw (gen_rtx_SET (VOIDmode,
1224 gen_rtx_REG (word_mode,
1225 FIRST_PSEUDO_REGISTER * 2),
1227 NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0;
1230 /* Now make an insn like the one we would make when GCSE'ing and see if
1232 PUT_MODE (SET_DEST (PATTERN (test_insn)), GET_MODE (x));
1233 SET_SRC (PATTERN (test_insn)) = x;
1234 return ((icode = recog (PATTERN (test_insn), test_insn, &num_clobbers)) >= 0
1235 && (num_clobbers == 0 || ! added_clobbers_hard_reg_p (icode)));
1238 /* Return nonzero if the operands of expression X are unchanged from the
1239 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1240 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1243 oprs_unchanged_p (const_rtx x, const_rtx insn, int avail_p)
1252 code = GET_CODE (x);
1257 struct reg_avail_info *info = ®_avail_info[REGNO (x)];
1259 if (info->last_bb != current_bb)
1262 return info->last_set < INSN_CUID (insn);
1264 return info->first_set >= INSN_CUID (insn);
1268 if (load_killed_in_block_p (current_bb, INSN_CUID (insn),
1272 return oprs_unchanged_p (XEXP (x, 0), insn, avail_p);
1299 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1303 /* If we are about to do the last recursive call needed at this
1304 level, change it into iteration. This function is called enough
1307 return oprs_unchanged_p (XEXP (x, i), insn, avail_p);
1309 else if (! oprs_unchanged_p (XEXP (x, i), insn, avail_p))
1312 else if (fmt[i] == 'E')
1313 for (j = 0; j < XVECLEN (x, i); j++)
1314 if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p))
1321 /* Used for communication between mems_conflict_for_gcse_p and
1322 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1323 conflict between two memory references. */
1324 static int gcse_mems_conflict_p;
1326 /* Used for communication between mems_conflict_for_gcse_p and
1327 load_killed_in_block_p. A memory reference for a load instruction,
1328 mems_conflict_for_gcse_p will see if a memory store conflicts with
1329 this memory load. */
1330 static const_rtx gcse_mem_operand;
1332 /* DEST is the output of an instruction. If it is a memory reference, and
1333 possibly conflicts with the load found in gcse_mem_operand, then set
1334 gcse_mems_conflict_p to a nonzero value. */
1337 mems_conflict_for_gcse_p (rtx dest, const_rtx setter ATTRIBUTE_UNUSED,
1338 void *data ATTRIBUTE_UNUSED)
1340 while (GET_CODE (dest) == SUBREG
1341 || GET_CODE (dest) == ZERO_EXTRACT
1342 || GET_CODE (dest) == STRICT_LOW_PART)
1343 dest = XEXP (dest, 0);
1345 /* If DEST is not a MEM, then it will not conflict with the load. Note
1346 that function calls are assumed to clobber memory, but are handled
1351 /* If we are setting a MEM in our list of specially recognized MEMs,
1352 don't mark as killed this time. */
1354 if (expr_equiv_p (dest, gcse_mem_operand) && pre_ldst_mems != NULL)
1356 if (!find_rtx_in_ldst (dest))
1357 gcse_mems_conflict_p = 1;
1361 if (true_dependence (dest, GET_MODE (dest), gcse_mem_operand,
1363 gcse_mems_conflict_p = 1;
1366 /* Return nonzero if the expression in X (a memory reference) is killed
1367 in block BB before or after the insn with the CUID in UID_LIMIT.
1368 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1371 To check the entire block, set UID_LIMIT to max_uid + 1 and
1375 load_killed_in_block_p (const_basic_block bb, int uid_limit, const_rtx x, int avail_p)
1377 rtx list_entry = modify_mem_list[bb->index];
1379 /* If this is a readonly then we aren't going to be changing it. */
1380 if (MEM_READONLY_P (x))
1386 /* Ignore entries in the list that do not apply. */
1388 && INSN_CUID (XEXP (list_entry, 0)) < uid_limit)
1390 && INSN_CUID (XEXP (list_entry, 0)) > uid_limit))
1392 list_entry = XEXP (list_entry, 1);
1396 setter = XEXP (list_entry, 0);
1398 /* If SETTER is a call everything is clobbered. Note that calls
1399 to pure functions are never put on the list, so we need not
1400 worry about them. */
1401 if (CALL_P (setter))
1404 /* SETTER must be an INSN of some kind that sets memory. Call
1405 note_stores to examine each hunk of memory that is modified.
1407 The note_stores interface is pretty limited, so we have to
1408 communicate via global variables. Yuk. */
1409 gcse_mem_operand = x;
1410 gcse_mems_conflict_p = 0;
1411 note_stores (PATTERN (setter), mems_conflict_for_gcse_p, NULL);
1412 if (gcse_mems_conflict_p)
1414 list_entry = XEXP (list_entry, 1);
1419 /* Return nonzero if the operands of expression X are unchanged from
1420 the start of INSN's basic block up to but not including INSN. */
1423 oprs_anticipatable_p (const_rtx x, const_rtx insn)
1425 return oprs_unchanged_p (x, insn, 0);
1428 /* Return nonzero if the operands of expression X are unchanged from
1429 INSN to the end of INSN's basic block. */
1432 oprs_available_p (const_rtx x, const_rtx insn)
1434 return oprs_unchanged_p (x, insn, 1);
1437 /* Hash expression X.
1439 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1440 indicating if a volatile operand is found or if the expression contains
1441 something we don't want to insert in the table. HASH_TABLE_SIZE is
1442 the current size of the hash table to be probed. */
1445 hash_expr (const_rtx x, enum machine_mode mode, int *do_not_record_p,
1446 int hash_table_size)
1450 *do_not_record_p = 0;
1452 hash = hash_rtx (x, mode, do_not_record_p,
1453 NULL, /*have_reg_qty=*/false);
1454 return hash % hash_table_size;
1457 /* Hash a set of register REGNO.
1459 Sets are hashed on the register that is set. This simplifies the PRE copy
1462 ??? May need to make things more elaborate. Later, as necessary. */
1465 hash_set (int regno, int hash_table_size)
1470 return hash % hash_table_size;
1473 /* Return nonzero if exp1 is equivalent to exp2. */
1476 expr_equiv_p (const_rtx x, const_rtx y)
1478 return exp_equiv_p (x, y, 0, true);
1481 /* Insert expression X in INSN in the hash TABLE.
1482 If it is already present, record it as the last occurrence in INSN's
1485 MODE is the mode of the value X is being stored into.
1486 It is only used if X is a CONST_INT.
1488 ANTIC_P is nonzero if X is an anticipatable expression.
1489 AVAIL_P is nonzero if X is an available expression. */
1492 insert_expr_in_table (rtx x, enum machine_mode mode, rtx insn, int antic_p,
1493 int avail_p, struct hash_table *table)
1495 int found, do_not_record_p;
1497 struct expr *cur_expr, *last_expr = NULL;
1498 struct occr *antic_occr, *avail_occr;
1500 hash = hash_expr (x, mode, &do_not_record_p, table->size);
1502 /* Do not insert expression in table if it contains volatile operands,
1503 or if hash_expr determines the expression is something we don't want
1504 to or can't handle. */
1505 if (do_not_record_p)
1508 cur_expr = table->table[hash];
1511 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
1513 /* If the expression isn't found, save a pointer to the end of
1515 last_expr = cur_expr;
1516 cur_expr = cur_expr->next_same_hash;
1521 cur_expr = gcse_alloc (sizeof (struct expr));
1522 bytes_used += sizeof (struct expr);
1523 if (table->table[hash] == NULL)
1524 /* This is the first pattern that hashed to this index. */
1525 table->table[hash] = cur_expr;
1527 /* Add EXPR to end of this hash chain. */
1528 last_expr->next_same_hash = cur_expr;
1530 /* Set the fields of the expr element. */
1532 cur_expr->bitmap_index = table->n_elems++;
1533 cur_expr->next_same_hash = NULL;
1534 cur_expr->antic_occr = NULL;
1535 cur_expr->avail_occr = NULL;
1538 /* Now record the occurrence(s). */
1541 antic_occr = cur_expr->antic_occr;
1543 if (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn))
1547 /* Found another instance of the expression in the same basic block.
1548 Prefer the currently recorded one. We want the first one in the
1549 block and the block is scanned from start to end. */
1550 ; /* nothing to do */
1553 /* First occurrence of this expression in this basic block. */
1554 antic_occr = gcse_alloc (sizeof (struct occr));
1555 bytes_used += sizeof (struct occr);
1556 antic_occr->insn = insn;
1557 antic_occr->next = cur_expr->antic_occr;
1558 antic_occr->deleted_p = 0;
1559 cur_expr->antic_occr = antic_occr;
1565 avail_occr = cur_expr->avail_occr;
1567 if (avail_occr && BLOCK_NUM (avail_occr->insn) == BLOCK_NUM (insn))
1569 /* Found another instance of the expression in the same basic block.
1570 Prefer this occurrence to the currently recorded one. We want
1571 the last one in the block and the block is scanned from start
1573 avail_occr->insn = insn;
1577 /* First occurrence of this expression in this basic block. */
1578 avail_occr = gcse_alloc (sizeof (struct occr));
1579 bytes_used += sizeof (struct occr);
1580 avail_occr->insn = insn;
1581 avail_occr->next = cur_expr->avail_occr;
1582 avail_occr->deleted_p = 0;
1583 cur_expr->avail_occr = avail_occr;
1588 /* Insert pattern X in INSN in the hash table.
1589 X is a SET of a reg to either another reg or a constant.
1590 If it is already present, record it as the last occurrence in INSN's
1594 insert_set_in_table (rtx x, rtx insn, struct hash_table *table)
1598 struct expr *cur_expr, *last_expr = NULL;
1599 struct occr *cur_occr;
1601 gcc_assert (GET_CODE (x) == SET && REG_P (SET_DEST (x)));
1603 hash = hash_set (REGNO (SET_DEST (x)), table->size);
1605 cur_expr = table->table[hash];
1608 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
1610 /* If the expression isn't found, save a pointer to the end of
1612 last_expr = cur_expr;
1613 cur_expr = cur_expr->next_same_hash;
1618 cur_expr = gcse_alloc (sizeof (struct expr));
1619 bytes_used += sizeof (struct expr);
1620 if (table->table[hash] == NULL)
1621 /* This is the first pattern that hashed to this index. */
1622 table->table[hash] = cur_expr;
1624 /* Add EXPR to end of this hash chain. */
1625 last_expr->next_same_hash = cur_expr;
1627 /* Set the fields of the expr element.
1628 We must copy X because it can be modified when copy propagation is
1629 performed on its operands. */
1630 cur_expr->expr = copy_rtx (x);
1631 cur_expr->bitmap_index = table->n_elems++;
1632 cur_expr->next_same_hash = NULL;
1633 cur_expr->antic_occr = NULL;
1634 cur_expr->avail_occr = NULL;
1637 /* Now record the occurrence. */
1638 cur_occr = cur_expr->avail_occr;
1640 if (cur_occr && BLOCK_NUM (cur_occr->insn) == BLOCK_NUM (insn))
1642 /* Found another instance of the expression in the same basic block.
1643 Prefer this occurrence to the currently recorded one. We want
1644 the last one in the block and the block is scanned from start
1646 cur_occr->insn = insn;
1650 /* First occurrence of this expression in this basic block. */
1651 cur_occr = gcse_alloc (sizeof (struct occr));
1652 bytes_used += sizeof (struct occr);
1654 cur_occr->insn = insn;
1655 cur_occr->next = cur_expr->avail_occr;
1656 cur_occr->deleted_p = 0;
1657 cur_expr->avail_occr = cur_occr;
1661 /* Determine whether the rtx X should be treated as a constant for
1662 the purposes of GCSE's constant propagation. */
1665 gcse_constant_p (const_rtx x)
1667 /* Consider a COMPARE of two integers constant. */
1668 if (GET_CODE (x) == COMPARE
1669 && GET_CODE (XEXP (x, 0)) == CONST_INT
1670 && GET_CODE (XEXP (x, 1)) == CONST_INT)
1673 /* Consider a COMPARE of the same registers is a constant
1674 if they are not floating point registers. */
1675 if (GET_CODE(x) == COMPARE
1676 && REG_P (XEXP (x, 0)) && REG_P (XEXP (x, 1))
1677 && REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 1))
1678 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 0)))
1679 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 1))))
1682 return CONSTANT_P (x);
1685 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
1689 hash_scan_set (rtx pat, rtx insn, struct hash_table *table)
1691 rtx src = SET_SRC (pat);
1692 rtx dest = SET_DEST (pat);
1695 if (GET_CODE (src) == CALL)
1696 hash_scan_call (src, insn, table);
1698 else if (REG_P (dest))
1700 unsigned int regno = REGNO (dest);
1703 /* See if a REG_NOTE shows this equivalent to a simpler expression.
1704 This allows us to do a single GCSE pass and still eliminate
1705 redundant constants, addresses or other expressions that are
1706 constructed with multiple instructions. */
1707 note = find_reg_equal_equiv_note (insn);
1710 ? gcse_constant_p (XEXP (note, 0))
1711 : want_to_gcse_p (XEXP (note, 0))))
1712 src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src);
1714 /* Only record sets of pseudo-regs in the hash table. */
1716 && regno >= FIRST_PSEUDO_REGISTER
1717 /* Don't GCSE something if we can't do a reg/reg copy. */
1718 && can_copy_p (GET_MODE (dest))
1719 /* GCSE commonly inserts instruction after the insn. We can't
1720 do that easily for EH_REGION notes so disable GCSE on these
1722 && !find_reg_note (insn, REG_EH_REGION, NULL_RTX)
1723 /* Is SET_SRC something we want to gcse? */
1724 && want_to_gcse_p (src)
1725 /* Don't CSE a nop. */
1726 && ! set_noop_p (pat)
1727 /* Don't GCSE if it has attached REG_EQUIV note.
1728 At this point this only function parameters should have
1729 REG_EQUIV notes and if the argument slot is used somewhere
1730 explicitly, it means address of parameter has been taken,
1731 so we should not extend the lifetime of the pseudo. */
1732 && (note == NULL_RTX || ! MEM_P (XEXP (note, 0))))
1734 /* An expression is not anticipatable if its operands are
1735 modified before this insn or if this is not the only SET in
1736 this insn. The latter condition does not have to mean that
1737 SRC itself is not anticipatable, but we just will not be
1738 able to handle code motion of insns with multiple sets. */
1739 int antic_p = oprs_anticipatable_p (src, insn)
1740 && !multiple_sets (insn);
1741 /* An expression is not available if its operands are
1742 subsequently modified, including this insn. It's also not
1743 available if this is a branch, because we can't insert
1744 a set after the branch. */
1745 int avail_p = (oprs_available_p (src, insn)
1746 && ! JUMP_P (insn));
1748 insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p, table);
1751 /* Record sets for constant/copy propagation. */
1752 else if (table->set_p
1753 && regno >= FIRST_PSEUDO_REGISTER
1755 && REGNO (src) >= FIRST_PSEUDO_REGISTER
1756 && can_copy_p (GET_MODE (dest))
1757 && REGNO (src) != regno)
1758 || gcse_constant_p (src))
1759 /* A copy is not available if its src or dest is subsequently
1760 modified. Here we want to search from INSN+1 on, but
1761 oprs_available_p searches from INSN on. */
1762 && (insn == BB_END (BLOCK_FOR_INSN (insn))
1763 || (tmp = next_nonnote_insn (insn)) == NULL_RTX
1764 || BLOCK_FOR_INSN (tmp) != BLOCK_FOR_INSN (insn)
1765 || oprs_available_p (pat, tmp)))
1766 insert_set_in_table (pat, insn, table);
1768 /* In case of store we want to consider the memory value as available in
1769 the REG stored in that memory. This makes it possible to remove
1770 redundant loads from due to stores to the same location. */
1771 else if (flag_gcse_las && REG_P (src) && MEM_P (dest))
1773 unsigned int regno = REGNO (src);
1775 /* Do not do this for constant/copy propagation. */
1777 /* Only record sets of pseudo-regs in the hash table. */
1778 && regno >= FIRST_PSEUDO_REGISTER
1779 /* Don't GCSE something if we can't do a reg/reg copy. */
1780 && can_copy_p (GET_MODE (src))
1781 /* GCSE commonly inserts instruction after the insn. We can't
1782 do that easily for EH_REGION notes so disable GCSE on these
1784 && ! find_reg_note (insn, REG_EH_REGION, NULL_RTX)
1785 /* Is SET_DEST something we want to gcse? */
1786 && want_to_gcse_p (dest)
1787 /* Don't CSE a nop. */
1788 && ! set_noop_p (pat)
1789 /* Don't GCSE if it has attached REG_EQUIV note.
1790 At this point this only function parameters should have
1791 REG_EQUIV notes and if the argument slot is used somewhere
1792 explicitly, it means address of parameter has been taken,
1793 so we should not extend the lifetime of the pseudo. */
1794 && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
1795 || ! MEM_P (XEXP (note, 0))))
1797 /* Stores are never anticipatable. */
1799 /* An expression is not available if its operands are
1800 subsequently modified, including this insn. It's also not
1801 available if this is a branch, because we can't insert
1802 a set after the branch. */
1803 int avail_p = oprs_available_p (dest, insn)
1806 /* Record the memory expression (DEST) in the hash table. */
1807 insert_expr_in_table (dest, GET_MODE (dest), insn,
1808 antic_p, avail_p, table);
1814 hash_scan_clobber (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
1815 struct hash_table *table ATTRIBUTE_UNUSED)
1817 /* Currently nothing to do. */
1821 hash_scan_call (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
1822 struct hash_table *table ATTRIBUTE_UNUSED)
1824 /* Currently nothing to do. */
1827 /* Process INSN and add hash table entries as appropriate.
1829 Only available expressions that set a single pseudo-reg are recorded.
1831 Single sets in a PARALLEL could be handled, but it's an extra complication
1832 that isn't dealt with right now. The trick is handling the CLOBBERs that
1833 are also in the PARALLEL. Later.
1835 If SET_P is nonzero, this is for the assignment hash table,
1836 otherwise it is for the expression hash table.
1837 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
1838 not record any expressions. */
1841 hash_scan_insn (rtx insn, struct hash_table *table, int in_libcall_block)
1843 rtx pat = PATTERN (insn);
1846 if (in_libcall_block)
1849 /* Pick out the sets of INSN and for other forms of instructions record
1850 what's been modified. */
1852 if (GET_CODE (pat) == SET)
1853 hash_scan_set (pat, insn, table);
1854 else if (GET_CODE (pat) == PARALLEL)
1855 for (i = 0; i < XVECLEN (pat, 0); i++)
1857 rtx x = XVECEXP (pat, 0, i);
1859 if (GET_CODE (x) == SET)
1860 hash_scan_set (x, insn, table);
1861 else if (GET_CODE (x) == CLOBBER)
1862 hash_scan_clobber (x, insn, table);
1863 else if (GET_CODE (x) == CALL)
1864 hash_scan_call (x, insn, table);
1867 else if (GET_CODE (pat) == CLOBBER)
1868 hash_scan_clobber (pat, insn, table);
1869 else if (GET_CODE (pat) == CALL)
1870 hash_scan_call (pat, insn, table);
1874 dump_hash_table (FILE *file, const char *name, struct hash_table *table)
1877 /* Flattened out table, so it's printed in proper order. */
1878 struct expr **flat_table;
1879 unsigned int *hash_val;
1882 flat_table = xcalloc (table->n_elems, sizeof (struct expr *));
1883 hash_val = xmalloc (table->n_elems * sizeof (unsigned int));
1885 for (i = 0; i < (int) table->size; i++)
1886 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
1888 flat_table[expr->bitmap_index] = expr;
1889 hash_val[expr->bitmap_index] = i;
1892 fprintf (file, "%s hash table (%d buckets, %d entries)\n",
1893 name, table->size, table->n_elems);
1895 for (i = 0; i < (int) table->n_elems; i++)
1896 if (flat_table[i] != 0)
1898 expr = flat_table[i];
1899 fprintf (file, "Index %d (hash value %d)\n ",
1900 expr->bitmap_index, hash_val[i]);
1901 print_rtl (file, expr->expr);
1902 fprintf (file, "\n");
1905 fprintf (file, "\n");
1911 /* Record register first/last/block set information for REGNO in INSN.
1913 first_set records the first place in the block where the register
1914 is set and is used to compute "anticipatability".
1916 last_set records the last place in the block where the register
1917 is set and is used to compute "availability".
1919 last_bb records the block for which first_set and last_set are
1920 valid, as a quick test to invalidate them.
1922 reg_set_in_block records whether the register is set in the block
1923 and is used to compute "transparency". */
1926 record_last_reg_set_info (rtx insn, int regno)
1928 struct reg_avail_info *info = ®_avail_info[regno];
1929 int cuid = INSN_CUID (insn);
1931 info->last_set = cuid;
1932 if (info->last_bb != current_bb)
1934 info->last_bb = current_bb;
1935 info->first_set = cuid;
1936 SET_BIT (reg_set_in_block[current_bb->index], regno);
1941 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
1942 Note we store a pair of elements in the list, so they have to be
1943 taken off pairwise. */
1946 canon_list_insert (rtx dest ATTRIBUTE_UNUSED, const_rtx unused1 ATTRIBUTE_UNUSED,
1949 rtx dest_addr, insn;
1952 while (GET_CODE (dest) == SUBREG
1953 || GET_CODE (dest) == ZERO_EXTRACT
1954 || GET_CODE (dest) == STRICT_LOW_PART)
1955 dest = XEXP (dest, 0);
1957 /* If DEST is not a MEM, then it will not conflict with a load. Note
1958 that function calls are assumed to clobber memory, but are handled
1964 dest_addr = get_addr (XEXP (dest, 0));
1965 dest_addr = canon_rtx (dest_addr);
1966 insn = (rtx) v_insn;
1967 bb = BLOCK_NUM (insn);
1969 canon_modify_mem_list[bb] =
1970 alloc_EXPR_LIST (VOIDmode, dest_addr, canon_modify_mem_list[bb]);
1971 canon_modify_mem_list[bb] =
1972 alloc_EXPR_LIST (VOIDmode, dest, canon_modify_mem_list[bb]);
1975 /* Record memory modification information for INSN. We do not actually care
1976 about the memory location(s) that are set, or even how they are set (consider
1977 a CALL_INSN). We merely need to record which insns modify memory. */
1980 record_last_mem_set_info (rtx insn)
1982 int bb = BLOCK_NUM (insn);
1984 /* load_killed_in_block_p will handle the case of calls clobbering
1986 modify_mem_list[bb] = alloc_INSN_LIST (insn, modify_mem_list[bb]);
1987 bitmap_set_bit (modify_mem_list_set, bb);
1991 /* Note that traversals of this loop (other than for free-ing)
1992 will break after encountering a CALL_INSN. So, there's no
1993 need to insert a pair of items, as canon_list_insert does. */
1994 canon_modify_mem_list[bb] =
1995 alloc_INSN_LIST (insn, canon_modify_mem_list[bb]);
1996 bitmap_set_bit (blocks_with_calls, bb);
1999 note_stores (PATTERN (insn), canon_list_insert, (void*) insn);
2002 /* Called from compute_hash_table via note_stores to handle one
2003 SET or CLOBBER in an insn. DATA is really the instruction in which
2004 the SET is taking place. */
2007 record_last_set_info (rtx dest, const_rtx setter ATTRIBUTE_UNUSED, void *data)
2009 rtx last_set_insn = (rtx) data;
2011 if (GET_CODE (dest) == SUBREG)
2012 dest = SUBREG_REG (dest);
2015 record_last_reg_set_info (last_set_insn, REGNO (dest));
2016 else if (MEM_P (dest)
2017 /* Ignore pushes, they clobber nothing. */
2018 && ! push_operand (dest, GET_MODE (dest)))
2019 record_last_mem_set_info (last_set_insn);
2022 /* Top level function to create an expression or assignment hash table.
2024 Expression entries are placed in the hash table if
2025 - they are of the form (set (pseudo-reg) src),
2026 - src is something we want to perform GCSE on,
2027 - none of the operands are subsequently modified in the block
2029 Assignment entries are placed in the hash table if
2030 - they are of the form (set (pseudo-reg) src),
2031 - src is something we want to perform const/copy propagation on,
2032 - none of the operands or target are subsequently modified in the block
2034 Currently src must be a pseudo-reg or a const_int.
2036 TABLE is the table computed. */
2039 compute_hash_table_work (struct hash_table *table)
2043 /* While we compute the hash table we also compute a bit array of which
2044 registers are set in which blocks.
2045 ??? This isn't needed during const/copy propagation, but it's cheap to
2047 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
2049 /* re-Cache any INSN_LIST nodes we have allocated. */
2050 clear_modify_mem_tables ();
2051 /* Some working arrays used to track first and last set in each block. */
2052 reg_avail_info = gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
2054 for (i = 0; i < max_gcse_regno; ++i)
2055 reg_avail_info[i].last_bb = NULL;
2057 FOR_EACH_BB (current_bb)
2061 int in_libcall_block;
2063 /* First pass over the instructions records information used to
2064 determine when registers and memory are first and last set.
2065 ??? hard-reg reg_set_in_block computation
2066 could be moved to compute_sets since they currently don't change. */
2068 FOR_BB_INSNS (current_bb, insn)
2070 if (! INSN_P (insn))
2075 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2076 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2077 record_last_reg_set_info (insn, regno);
2082 note_stores (PATTERN (insn), record_last_set_info, insn);
2085 /* Insert implicit sets in the hash table. */
2087 && implicit_sets[current_bb->index] != NULL_RTX)
2088 hash_scan_set (implicit_sets[current_bb->index],
2089 BB_HEAD (current_bb), table);
2091 /* The next pass builds the hash table. */
2092 in_libcall_block = 0;
2093 FOR_BB_INSNS (current_bb, insn)
2096 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2097 in_libcall_block = 1;
2098 else if (table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2099 in_libcall_block = 0;
2100 hash_scan_insn (insn, table, in_libcall_block);
2101 if (!table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2102 in_libcall_block = 0;
2106 free (reg_avail_info);
2107 reg_avail_info = NULL;
2110 /* Allocate space for the set/expr hash TABLE.
2111 N_INSNS is the number of instructions in the function.
2112 It is used to determine the number of buckets to use.
2113 SET_P determines whether set or expression table will
2117 alloc_hash_table (int n_insns, struct hash_table *table, int set_p)
2121 table->size = n_insns / 4;
2122 if (table->size < 11)
2125 /* Attempt to maintain efficient use of hash table.
2126 Making it an odd number is simplest for now.
2127 ??? Later take some measurements. */
2129 n = table->size * sizeof (struct expr *);
2130 table->table = gmalloc (n);
2131 table->set_p = set_p;
2134 /* Free things allocated by alloc_hash_table. */
2137 free_hash_table (struct hash_table *table)
2139 free (table->table);
2142 /* Compute the hash TABLE for doing copy/const propagation or
2143 expression hash table. */
2146 compute_hash_table (struct hash_table *table)
2148 /* Initialize count of number of entries in hash table. */
2150 memset (table->table, 0, table->size * sizeof (struct expr *));
2152 compute_hash_table_work (table);
2155 /* Expression tracking support. */
2157 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2158 table entry, or NULL if not found. */
2160 static struct expr *
2161 lookup_set (unsigned int regno, struct hash_table *table)
2163 unsigned int hash = hash_set (regno, table->size);
2166 expr = table->table[hash];
2168 while (expr && REGNO (SET_DEST (expr->expr)) != regno)
2169 expr = expr->next_same_hash;
2174 /* Return the next entry for REGNO in list EXPR. */
2176 static struct expr *
2177 next_set (unsigned int regno, struct expr *expr)
2180 expr = expr->next_same_hash;
2181 while (expr && REGNO (SET_DEST (expr->expr)) != regno);
2186 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2187 types may be mixed. */
2190 free_insn_expr_list_list (rtx *listp)
2194 for (list = *listp; list ; list = next)
2196 next = XEXP (list, 1);
2197 if (GET_CODE (list) == EXPR_LIST)
2198 free_EXPR_LIST_node (list);
2200 free_INSN_LIST_node (list);
2206 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2208 clear_modify_mem_tables (void)
2213 EXECUTE_IF_SET_IN_BITMAP (modify_mem_list_set, 0, i, bi)
2215 free_INSN_LIST_list (modify_mem_list + i);
2216 free_insn_expr_list_list (canon_modify_mem_list + i);
2218 bitmap_clear (modify_mem_list_set);
2219 bitmap_clear (blocks_with_calls);
2222 /* Release memory used by modify_mem_list_set. */
2225 free_modify_mem_tables (void)
2227 clear_modify_mem_tables ();
2228 free (modify_mem_list);
2229 free (canon_modify_mem_list);
2230 modify_mem_list = 0;
2231 canon_modify_mem_list = 0;
2234 /* Reset tables used to keep track of what's still available [since the
2235 start of the block]. */
2238 reset_opr_set_tables (void)
2240 /* Maintain a bitmap of which regs have been set since beginning of
2242 CLEAR_REG_SET (reg_set_bitmap);
2244 /* Also keep a record of the last instruction to modify memory.
2245 For now this is very trivial, we only record whether any memory
2246 location has been modified. */
2247 clear_modify_mem_tables ();
2250 /* Return nonzero if the operands of X are not set before INSN in
2251 INSN's basic block. */
2254 oprs_not_set_p (const_rtx x, const_rtx insn)
2263 code = GET_CODE (x);
2280 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn),
2281 INSN_CUID (insn), x, 0))
2284 return oprs_not_set_p (XEXP (x, 0), insn);
2287 return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x));
2293 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2297 /* If we are about to do the last recursive call
2298 needed at this level, change it into iteration.
2299 This function is called enough to be worth it. */
2301 return oprs_not_set_p (XEXP (x, i), insn);
2303 if (! oprs_not_set_p (XEXP (x, i), insn))
2306 else if (fmt[i] == 'E')
2307 for (j = 0; j < XVECLEN (x, i); j++)
2308 if (! oprs_not_set_p (XVECEXP (x, i, j), insn))
2315 /* Mark things set by a CALL. */
2318 mark_call (rtx insn)
2320 if (! CONST_OR_PURE_CALL_P (insn))
2321 record_last_mem_set_info (insn);
2324 /* Mark things set by a SET. */
2327 mark_set (rtx pat, rtx insn)
2329 rtx dest = SET_DEST (pat);
2331 while (GET_CODE (dest) == SUBREG
2332 || GET_CODE (dest) == ZERO_EXTRACT
2333 || GET_CODE (dest) == STRICT_LOW_PART)
2334 dest = XEXP (dest, 0);
2337 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (dest));
2338 else if (MEM_P (dest))
2339 record_last_mem_set_info (insn);
2341 if (GET_CODE (SET_SRC (pat)) == CALL)
2345 /* Record things set by a CLOBBER. */
2348 mark_clobber (rtx pat, rtx insn)
2350 rtx clob = XEXP (pat, 0);
2352 while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART)
2353 clob = XEXP (clob, 0);
2356 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (clob));
2358 record_last_mem_set_info (insn);
2361 /* Record things set by INSN.
2362 This data is used by oprs_not_set_p. */
2365 mark_oprs_set (rtx insn)
2367 rtx pat = PATTERN (insn);
2370 if (GET_CODE (pat) == SET)
2371 mark_set (pat, insn);
2372 else if (GET_CODE (pat) == PARALLEL)
2373 for (i = 0; i < XVECLEN (pat, 0); i++)
2375 rtx x = XVECEXP (pat, 0, i);
2377 if (GET_CODE (x) == SET)
2379 else if (GET_CODE (x) == CLOBBER)
2380 mark_clobber (x, insn);
2381 else if (GET_CODE (x) == CALL)
2385 else if (GET_CODE (pat) == CLOBBER)
2386 mark_clobber (pat, insn);
2387 else if (GET_CODE (pat) == CALL)
2392 /* Compute copy/constant propagation working variables. */
2394 /* Local properties of assignments. */
2395 static sbitmap *cprop_pavloc;
2396 static sbitmap *cprop_absaltered;
2398 /* Global properties of assignments (computed from the local properties). */
2399 static sbitmap *cprop_avin;
2400 static sbitmap *cprop_avout;
2402 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
2403 basic blocks. N_SETS is the number of sets. */
2406 alloc_cprop_mem (int n_blocks, int n_sets)
2408 cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
2409 cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
2411 cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
2412 cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
2415 /* Free vars used by copy/const propagation. */
2418 free_cprop_mem (void)
2420 sbitmap_vector_free (cprop_pavloc);
2421 sbitmap_vector_free (cprop_absaltered);
2422 sbitmap_vector_free (cprop_avin);
2423 sbitmap_vector_free (cprop_avout);
2426 /* For each block, compute whether X is transparent. X is either an
2427 expression or an assignment [though we don't care which, for this context
2428 an assignment is treated as an expression]. For each block where an
2429 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
2433 compute_transp (const_rtx x, int indx, sbitmap *bmap, int set_p)
2441 /* repeat is used to turn tail-recursion into iteration since GCC
2442 can't do it when there's no return value. */
2448 code = GET_CODE (x);
2454 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
2457 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
2458 SET_BIT (bmap[bb->index], indx);
2462 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
2463 SET_BIT (bmap[r->bb_index], indx);
2468 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
2471 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
2472 RESET_BIT (bmap[bb->index], indx);
2476 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
2477 RESET_BIT (bmap[r->bb_index], indx);
2484 if (! MEM_READONLY_P (x))
2489 /* First handle all the blocks with calls. We don't need to
2490 do any list walking for them. */
2491 EXECUTE_IF_SET_IN_BITMAP (blocks_with_calls, 0, bb_index, bi)
2494 SET_BIT (bmap[bb_index], indx);
2496 RESET_BIT (bmap[bb_index], indx);
2499 /* Now iterate over the blocks which have memory modifications
2500 but which do not have any calls. */
2501 EXECUTE_IF_AND_COMPL_IN_BITMAP (modify_mem_list_set,
2505 rtx list_entry = canon_modify_mem_list[bb_index];
2509 rtx dest, dest_addr;
2511 /* LIST_ENTRY must be an INSN of some kind that sets memory.
2512 Examine each hunk of memory that is modified. */
2514 dest = XEXP (list_entry, 0);
2515 list_entry = XEXP (list_entry, 1);
2516 dest_addr = XEXP (list_entry, 0);
2518 if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
2519 x, rtx_addr_varies_p))
2522 SET_BIT (bmap[bb_index], indx);
2524 RESET_BIT (bmap[bb_index], indx);
2527 list_entry = XEXP (list_entry, 1);
2552 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2556 /* If we are about to do the last recursive call
2557 needed at this level, change it into iteration.
2558 This function is called enough to be worth it. */
2565 compute_transp (XEXP (x, i), indx, bmap, set_p);
2567 else if (fmt[i] == 'E')
2568 for (j = 0; j < XVECLEN (x, i); j++)
2569 compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
2573 /* Top level routine to do the dataflow analysis needed by copy/const
2577 compute_cprop_data (void)
2579 compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, &set_hash_table);
2580 compute_available (cprop_pavloc, cprop_absaltered,
2581 cprop_avout, cprop_avin);
2584 /* Copy/constant propagation. */
2586 /* Maximum number of register uses in an insn that we handle. */
2589 /* Table of uses found in an insn.
2590 Allocated statically to avoid alloc/free complexity and overhead. */
2591 static struct reg_use reg_use_table[MAX_USES];
2593 /* Index into `reg_use_table' while building it. */
2594 static int reg_use_count;
2596 /* Set up a list of register numbers used in INSN. The found uses are stored
2597 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
2598 and contains the number of uses in the table upon exit.
2600 ??? If a register appears multiple times we will record it multiple times.
2601 This doesn't hurt anything but it will slow things down. */
2604 find_used_regs (rtx *xptr, void *data ATTRIBUTE_UNUSED)
2611 /* repeat is used to turn tail-recursion into iteration since GCC
2612 can't do it when there's no return value. */
2617 code = GET_CODE (x);
2620 if (reg_use_count == MAX_USES)
2623 reg_use_table[reg_use_count].reg_rtx = x;
2627 /* Recursively scan the operands of this expression. */
2629 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2633 /* If we are about to do the last recursive call
2634 needed at this level, change it into iteration.
2635 This function is called enough to be worth it. */
2642 find_used_regs (&XEXP (x, i), data);
2644 else if (fmt[i] == 'E')
2645 for (j = 0; j < XVECLEN (x, i); j++)
2646 find_used_regs (&XVECEXP (x, i, j), data);
2650 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
2651 Returns nonzero is successful. */
2654 try_replace_reg (rtx from, rtx to, rtx insn)
2656 rtx note = find_reg_equal_equiv_note (insn);
2659 rtx set = single_set (insn);
2661 /* Usually we substitute easy stuff, so we won't copy everything.
2662 We however need to take care to not duplicate non-trivial CONST
2666 validate_replace_src_group (from, to, insn);
2667 if (num_changes_pending () && apply_change_group ())
2670 /* Try to simplify SET_SRC if we have substituted a constant. */
2671 if (success && set && CONSTANT_P (to))
2673 src = simplify_rtx (SET_SRC (set));
2676 validate_change (insn, &SET_SRC (set), src, 0);
2679 /* If there is already a REG_EQUAL note, update the expression in it
2680 with our replacement. */
2681 if (note != 0 && REG_NOTE_KIND (note) == REG_EQUAL)
2682 set_unique_reg_note (insn, REG_EQUAL,
2683 simplify_replace_rtx (XEXP (note, 0), from, to));
2684 if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
2686 /* If above failed and this is a single set, try to simplify the source of
2687 the set given our substitution. We could perhaps try this for multiple
2688 SETs, but it probably won't buy us anything. */
2689 src = simplify_replace_rtx (SET_SRC (set), from, to);
2691 if (!rtx_equal_p (src, SET_SRC (set))
2692 && validate_change (insn, &SET_SRC (set), src, 0))
2695 /* If we've failed to do replacement, have a single SET, don't already
2696 have a note, and have no special SET, add a REG_EQUAL note to not
2697 lose information. */
2698 if (!success && note == 0 && set != 0
2699 && GET_CODE (SET_DEST (set)) != ZERO_EXTRACT
2700 && GET_CODE (SET_DEST (set)) != STRICT_LOW_PART)
2701 note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
2704 /* REG_EQUAL may get simplified into register.
2705 We don't allow that. Remove that note. This code ought
2706 not to happen, because previous code ought to synthesize
2707 reg-reg move, but be on the safe side. */
2708 if (note && REG_NOTE_KIND (note) == REG_EQUAL && REG_P (XEXP (note, 0)))
2709 remove_note (insn, note);
2714 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
2715 NULL no such set is found. */
2717 static struct expr *
2718 find_avail_set (int regno, rtx insn)
2720 /* SET1 contains the last set found that can be returned to the caller for
2721 use in a substitution. */
2722 struct expr *set1 = 0;
2724 /* Loops are not possible here. To get a loop we would need two sets
2725 available at the start of the block containing INSN. i.e. we would
2726 need two sets like this available at the start of the block:
2728 (set (reg X) (reg Y))
2729 (set (reg Y) (reg X))
2731 This can not happen since the set of (reg Y) would have killed the
2732 set of (reg X) making it unavailable at the start of this block. */
2736 struct expr *set = lookup_set (regno, &set_hash_table);
2738 /* Find a set that is available at the start of the block
2739 which contains INSN. */
2742 if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
2744 set = next_set (regno, set);
2747 /* If no available set was found we've reached the end of the
2748 (possibly empty) copy chain. */
2752 gcc_assert (GET_CODE (set->expr) == SET);
2754 src = SET_SRC (set->expr);
2756 /* We know the set is available.
2757 Now check that SRC is ANTLOC (i.e. none of the source operands
2758 have changed since the start of the block).
2760 If the source operand changed, we may still use it for the next
2761 iteration of this loop, but we may not use it for substitutions. */
2763 if (gcse_constant_p (src) || oprs_not_set_p (src, insn))
2766 /* If the source of the set is anything except a register, then
2767 we have reached the end of the copy chain. */
2771 /* Follow the copy chain, i.e. start another iteration of the loop
2772 and see if we have an available copy into SRC. */
2773 regno = REGNO (src);
2776 /* SET1 holds the last set that was available and anticipatable at
2781 /* Subroutine of cprop_insn that tries to propagate constants into
2782 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
2783 it is the instruction that immediately precedes JUMP, and must be a
2784 single SET of a register. FROM is what we will try to replace,
2785 SRC is the constant we will try to substitute for it. Returns nonzero
2786 if a change was made. */
2789 cprop_jump (basic_block bb, rtx setcc, rtx jump, rtx from, rtx src)
2791 rtx new, set_src, note_src;
2792 rtx set = pc_set (jump);
2793 rtx note = find_reg_equal_equiv_note (jump);
2797 note_src = XEXP (note, 0);
2798 if (GET_CODE (note_src) == EXPR_LIST)
2799 note_src = NULL_RTX;
2801 else note_src = NULL_RTX;
2803 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
2804 set_src = note_src ? note_src : SET_SRC (set);
2806 /* First substitute the SETCC condition into the JUMP instruction,
2807 then substitute that given values into this expanded JUMP. */
2808 if (setcc != NULL_RTX
2809 && !modified_between_p (from, setcc, jump)
2810 && !modified_between_p (src, setcc, jump))
2813 rtx setcc_set = single_set (setcc);
2814 rtx setcc_note = find_reg_equal_equiv_note (setcc);
2815 setcc_src = (setcc_note && GET_CODE (XEXP (setcc_note, 0)) != EXPR_LIST)
2816 ? XEXP (setcc_note, 0) : SET_SRC (setcc_set);
2817 set_src = simplify_replace_rtx (set_src, SET_DEST (setcc_set),
2823 new = simplify_replace_rtx (set_src, from, src);
2825 /* If no simplification can be made, then try the next register. */
2826 if (rtx_equal_p (new, SET_SRC (set)))
2829 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
2834 /* Ensure the value computed inside the jump insn to be equivalent
2835 to one computed by setcc. */
2836 if (setcc && modified_in_p (new, setcc))
2838 if (! validate_change (jump, &SET_SRC (set), new, 0))
2840 /* When (some) constants are not valid in a comparison, and there
2841 are two registers to be replaced by constants before the entire
2842 comparison can be folded into a constant, we need to keep
2843 intermediate information in REG_EQUAL notes. For targets with
2844 separate compare insns, such notes are added by try_replace_reg.
2845 When we have a combined compare-and-branch instruction, however,
2846 we need to attach a note to the branch itself to make this
2847 optimization work. */
2849 if (!rtx_equal_p (new, note_src))
2850 set_unique_reg_note (jump, REG_EQUAL, copy_rtx (new));
2854 /* Remove REG_EQUAL note after simplification. */
2856 remove_note (jump, note);
2860 /* Delete the cc0 setter. */
2861 if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
2862 delete_insn (setcc);
2865 run_jump_opt_after_gcse = 1;
2867 global_const_prop_count++;
2868 if (dump_file != NULL)
2871 "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
2872 REGNO (from), INSN_UID (jump));
2873 print_rtl (dump_file, src);
2874 fprintf (dump_file, "\n");
2876 purge_dead_edges (bb);
2878 /* If a conditional jump has been changed into unconditional jump, remove
2879 the jump and make the edge fallthru - this is always called in
2881 if (new != pc_rtx && simplejump_p (jump))
2886 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ei_next (&ei))
2887 if (e->dest != EXIT_BLOCK_PTR
2888 && BB_HEAD (e->dest) == JUMP_LABEL (jump))
2890 e->flags |= EDGE_FALLTHRU;
2900 constprop_register (rtx insn, rtx from, rtx to, bool alter_jumps)
2904 /* Check for reg or cc0 setting instructions followed by
2905 conditional branch instructions first. */
2907 && (sset = single_set (insn)) != NULL
2909 && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
2911 rtx dest = SET_DEST (sset);
2912 if ((REG_P (dest) || CC0_P (dest))
2913 && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to))
2917 /* Handle normal insns next. */
2918 if (NONJUMP_INSN_P (insn)
2919 && try_replace_reg (from, to, insn))
2922 /* Try to propagate a CONST_INT into a conditional jump.
2923 We're pretty specific about what we will handle in this
2924 code, we can extend this as necessary over time.
2926 Right now the insn in question must look like
2927 (set (pc) (if_then_else ...)) */
2928 else if (alter_jumps && any_condjump_p (insn) && onlyjump_p (insn))
2929 return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to);
2933 /* Perform constant and copy propagation on INSN.
2934 The result is nonzero if a change was made. */
2937 cprop_insn (rtx insn, int alter_jumps)
2939 struct reg_use *reg_used;
2947 note_uses (&PATTERN (insn), find_used_regs, NULL);
2949 note = find_reg_equal_equiv_note (insn);
2951 /* We may win even when propagating constants into notes. */
2953 find_used_regs (&XEXP (note, 0), NULL);
2955 for (reg_used = ®_use_table[0]; reg_use_count > 0;
2956 reg_used++, reg_use_count--)
2958 unsigned int regno = REGNO (reg_used->reg_rtx);
2962 /* Ignore registers created by GCSE.
2963 We do this because ... */
2964 if (regno >= max_gcse_regno)
2967 /* If the register has already been set in this block, there's
2968 nothing we can do. */
2969 if (! oprs_not_set_p (reg_used->reg_rtx, insn))
2972 /* Find an assignment that sets reg_used and is available
2973 at the start of the block. */
2974 set = find_avail_set (regno, insn);
2979 /* ??? We might be able to handle PARALLELs. Later. */
2980 gcc_assert (GET_CODE (pat) == SET);
2982 src = SET_SRC (pat);
2984 /* Constant propagation. */
2985 if (gcse_constant_p (src))
2987 if (constprop_register (insn, reg_used->reg_rtx, src, alter_jumps))
2990 global_const_prop_count++;
2991 if (dump_file != NULL)
2993 fprintf (dump_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
2994 fprintf (dump_file, "insn %d with constant ", INSN_UID (insn));
2995 print_rtl (dump_file, src);
2996 fprintf (dump_file, "\n");
2998 if (INSN_DELETED_P (insn))
3002 else if (REG_P (src)
3003 && REGNO (src) >= FIRST_PSEUDO_REGISTER
3004 && REGNO (src) != regno)
3006 if (try_replace_reg (reg_used->reg_rtx, src, insn))
3009 global_copy_prop_count++;
3010 if (dump_file != NULL)
3012 fprintf (dump_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
3013 regno, INSN_UID (insn));
3014 fprintf (dump_file, " with reg %d\n", REGNO (src));
3017 /* The original insn setting reg_used may or may not now be
3018 deletable. We leave the deletion to flow. */
3019 /* FIXME: If it turns out that the insn isn't deletable,
3020 then we may have unnecessarily extended register lifetimes
3021 and made things worse. */
3029 /* Like find_used_regs, but avoid recording uses that appear in
3030 input-output contexts such as zero_extract or pre_dec. This
3031 restricts the cases we consider to those for which local cprop
3032 can legitimately make replacements. */
3035 local_cprop_find_used_regs (rtx *xptr, void *data)
3042 switch (GET_CODE (x))
3046 case STRICT_LOW_PART:
3055 /* Can only legitimately appear this early in the context of
3056 stack pushes for function arguments, but handle all of the
3057 codes nonetheless. */
3061 /* Setting a subreg of a register larger than word_mode leaves
3062 the non-written words unchanged. */
3063 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
3071 find_used_regs (xptr, data);
3074 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3075 their REG_EQUAL notes need updating. */
3078 do_local_cprop (rtx x, rtx insn, bool alter_jumps, rtx *libcall_sp)
3080 rtx newreg = NULL, newcnst = NULL;
3082 /* Rule out USE instructions and ASM statements as we don't want to
3083 change the hard registers mentioned. */
3085 && (REGNO (x) >= FIRST_PSEUDO_REGISTER
3086 || (GET_CODE (PATTERN (insn)) != USE
3087 && asm_noperands (PATTERN (insn)) < 0)))
3089 cselib_val *val = cselib_lookup (x, GET_MODE (x), 0);
3090 struct elt_loc_list *l;
3094 for (l = val->locs; l; l = l->next)
3096 rtx this_rtx = l->loc;
3099 /* Don't CSE non-constant values out of libcall blocks. */
3100 if (l->in_libcall && ! CONSTANT_P (this_rtx))
3103 if (gcse_constant_p (this_rtx))
3105 if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
3106 /* Don't copy propagate if it has attached REG_EQUIV note.
3107 At this point this only function parameters should have
3108 REG_EQUIV notes and if the argument slot is used somewhere
3109 explicitly, it means address of parameter has been taken,
3110 so we should not extend the lifetime of the pseudo. */
3111 && (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX))
3112 || ! MEM_P (XEXP (note, 0))))
3115 if (newcnst && constprop_register (insn, x, newcnst, alter_jumps))
3117 /* If we find a case where we can't fix the retval REG_EQUAL notes
3118 match the new register, we either have to abandon this replacement
3119 or fix delete_trivially_dead_insns to preserve the setting insn,
3120 or make it delete the REG_EQUAL note, and fix up all passes that
3121 require the REG_EQUAL note there. */
3124 adjusted = adjust_libcall_notes (x, newcnst, insn, libcall_sp);
3125 gcc_assert (adjusted);
3127 if (dump_file != NULL)
3129 fprintf (dump_file, "LOCAL CONST-PROP: Replacing reg %d in ",
3131 fprintf (dump_file, "insn %d with constant ",
3133 print_rtl (dump_file, newcnst);
3134 fprintf (dump_file, "\n");
3136 local_const_prop_count++;
3139 else if (newreg && newreg != x && try_replace_reg (x, newreg, insn))
3141 adjust_libcall_notes (x, newreg, insn, libcall_sp);
3142 if (dump_file != NULL)
3145 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
3146 REGNO (x), INSN_UID (insn));
3147 fprintf (dump_file, " with reg %d\n", REGNO (newreg));
3149 local_copy_prop_count++;
3156 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3157 their REG_EQUAL notes need updating to reflect that OLDREG has been
3158 replaced with NEWVAL in INSN. Return true if all substitutions could
3161 adjust_libcall_notes (rtx oldreg, rtx newval, rtx insn, rtx *libcall_sp)
3165 while ((end = *libcall_sp++))
3167 rtx note = find_reg_equal_equiv_note (end);
3174 if (reg_set_between_p (newval, PREV_INSN (insn), end))
3178 note = find_reg_equal_equiv_note (end);
3181 if (reg_mentioned_p (newval, XEXP (note, 0)))
3184 while ((end = *libcall_sp++));
3188 XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), oldreg, newval);
3189 df_notes_rescan (end);
3195 #define MAX_NESTED_LIBCALLS 9
3197 /* Do local const/copy propagation (i.e. within each basic block).
3198 If ALTER_JUMPS is true, allow propagating into jump insns, which
3199 could modify the CFG. */
3202 local_cprop_pass (bool alter_jumps)
3206 struct reg_use *reg_used;
3207 rtx libcall_stack[MAX_NESTED_LIBCALLS + 1], *libcall_sp;
3208 bool changed = false;
3210 cselib_init (false);
3211 libcall_sp = &libcall_stack[MAX_NESTED_LIBCALLS];
3215 FOR_BB_INSNS (bb, insn)
3219 rtx note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
3223 gcc_assert (libcall_sp != libcall_stack);
3224 *--libcall_sp = XEXP (note, 0);
3226 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
3229 note = find_reg_equal_equiv_note (insn);
3233 note_uses (&PATTERN (insn), local_cprop_find_used_regs,
3236 local_cprop_find_used_regs (&XEXP (note, 0), NULL);
3238 for (reg_used = ®_use_table[0]; reg_use_count > 0;
3239 reg_used++, reg_use_count--)
3241 if (do_local_cprop (reg_used->reg_rtx, insn, alter_jumps,
3248 if (INSN_DELETED_P (insn))
3251 while (reg_use_count);
3253 cselib_process_insn (insn);
3256 /* Forget everything at the end of a basic block. Make sure we are
3257 not inside a libcall, they should never cross basic blocks. */
3258 cselib_clear_table ();
3259 gcc_assert (libcall_sp == &libcall_stack[MAX_NESTED_LIBCALLS]);
3264 /* Global analysis may get into infinite loops for unreachable blocks. */
3265 if (changed && alter_jumps)
3267 delete_unreachable_blocks ();
3268 free_reg_set_mem ();
3269 alloc_reg_set_mem (max_reg_num ());
3274 /* Forward propagate copies. This includes copies and constants. Return
3275 nonzero if a change was made. */
3278 cprop (int alter_jumps)
3284 /* Note we start at block 1. */
3285 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
3287 if (dump_file != NULL)
3288 fprintf (dump_file, "\n");
3293 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
3295 /* Reset tables used to keep track of what's still valid [since the
3296 start of the block]. */
3297 reset_opr_set_tables ();
3299 FOR_BB_INSNS (bb, insn)
3302 changed |= cprop_insn (insn, alter_jumps);
3304 /* Keep track of everything modified by this insn. */
3305 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
3306 call mark_oprs_set if we turned the insn into a NOTE. */
3307 if (! NOTE_P (insn))
3308 mark_oprs_set (insn);
3312 if (dump_file != NULL)
3313 fprintf (dump_file, "\n");
3318 /* Similar to get_condition, only the resulting condition must be
3319 valid at JUMP, instead of at EARLIEST.
3321 This differs from noce_get_condition in ifcvt.c in that we prefer not to
3322 settle for the condition variable in the jump instruction being integral.
3323 We prefer to be able to record the value of a user variable, rather than
3324 the value of a temporary used in a condition. This could be solved by
3325 recording the value of *every* register scanned by canonicalize_condition,
3326 but this would require some code reorganization. */
3329 fis_get_condition (rtx jump)
3331 return get_condition (jump, NULL, false, true);
3334 /* Check the comparison COND to see if we can safely form an implicit set from
3335 it. COND is either an EQ or NE comparison. */
3338 implicit_set_cond_p (const_rtx cond)
3340 const enum machine_mode mode = GET_MODE (XEXP (cond, 0));
3341 const_rtx cst = XEXP (cond, 1);
3343 /* We can't perform this optimization if either operand might be or might
3344 contain a signed zero. */
3345 if (HONOR_SIGNED_ZEROS (mode))
3347 /* It is sufficient to check if CST is or contains a zero. We must
3348 handle float, complex, and vector. If any subpart is a zero, then
3349 the optimization can't be performed. */
3350 /* ??? The complex and vector checks are not implemented yet. We just
3351 always return zero for them. */
3352 if (GET_CODE (cst) == CONST_DOUBLE)
3355 REAL_VALUE_FROM_CONST_DOUBLE (d, cst);
3356 if (REAL_VALUES_EQUAL (d, dconst0))
3363 return gcse_constant_p (cst);
3366 /* Find the implicit sets of a function. An "implicit set" is a constraint
3367 on the value of a variable, implied by a conditional jump. For example,
3368 following "if (x == 2)", the then branch may be optimized as though the
3369 conditional performed an "explicit set", in this example, "x = 2". This
3370 function records the set patterns that are implicit at the start of each
3374 find_implicit_sets (void)
3376 basic_block bb, dest;
3382 /* Check for more than one successor. */
3383 if (EDGE_COUNT (bb->succs) > 1)
3385 cond = fis_get_condition (BB_END (bb));
3388 && (GET_CODE (cond) == EQ || GET_CODE (cond) == NE)
3389 && REG_P (XEXP (cond, 0))
3390 && REGNO (XEXP (cond, 0)) >= FIRST_PSEUDO_REGISTER
3391 && implicit_set_cond_p (cond))
3393 dest = GET_CODE (cond) == EQ ? BRANCH_EDGE (bb)->dest
3394 : FALLTHRU_EDGE (bb)->dest;
3396 if (dest && single_pred_p (dest)
3397 && dest != EXIT_BLOCK_PTR)
3399 new = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
3401 implicit_sets[dest->index] = new;
3404 fprintf(dump_file, "Implicit set of reg %d in ",
3405 REGNO (XEXP (cond, 0)));
3406 fprintf(dump_file, "basic block %d\n", dest->index);
3414 fprintf (dump_file, "Found %d implicit sets\n", count);
3417 /* Perform one copy/constant propagation pass.
3418 PASS is the pass count. If CPROP_JUMPS is true, perform constant
3419 propagation into conditional jumps. If BYPASS_JUMPS is true,
3420 perform conditional jump bypassing optimizations. */
3423 one_cprop_pass (int pass, bool cprop_jumps, bool bypass_jumps)
3427 global_const_prop_count = local_const_prop_count = 0;
3428 global_copy_prop_count = local_copy_prop_count = 0;
3431 local_cprop_pass (cprop_jumps);
3433 /* Determine implicit sets. */
3434 implicit_sets = XCNEWVEC (rtx, last_basic_block);
3435 find_implicit_sets ();
3437 alloc_hash_table (max_cuid, &set_hash_table, 1);
3438 compute_hash_table (&set_hash_table);
3440 /* Free implicit_sets before peak usage. */
3441 free (implicit_sets);
3442 implicit_sets = NULL;
3445 dump_hash_table (dump_file, "SET", &set_hash_table);
3446 if (set_hash_table.n_elems > 0)
3448 alloc_cprop_mem (last_basic_block, set_hash_table.n_elems);
3449 compute_cprop_data ();
3450 changed = cprop (cprop_jumps);
3452 changed |= bypass_conditional_jumps ();
3456 free_hash_table (&set_hash_table);
3460 fprintf (dump_file, "CPROP of %s, pass %d: %d bytes needed, ",
3461 current_function_name (), pass, bytes_used);
3462 fprintf (dump_file, "%d local const props, %d local copy props, ",
3463 local_const_prop_count, local_copy_prop_count);
3464 fprintf (dump_file, "%d global const props, %d global copy props\n\n",
3465 global_const_prop_count, global_copy_prop_count);
3467 /* Global analysis may get into infinite loops for unreachable blocks. */
3468 if (changed && cprop_jumps)
3469 delete_unreachable_blocks ();
3474 /* Bypass conditional jumps. */
3476 /* The value of last_basic_block at the beginning of the jump_bypass
3477 pass. The use of redirect_edge_and_branch_force may introduce new
3478 basic blocks, but the data flow analysis is only valid for basic
3479 block indices less than bypass_last_basic_block. */
3481 static int bypass_last_basic_block;
3483 /* Find a set of REGNO to a constant that is available at the end of basic
3484 block BB. Returns NULL if no such set is found. Based heavily upon
3487 static struct expr *
3488 find_bypass_set (int regno, int bb)
3490 struct expr *result = 0;
3495 struct expr *set = lookup_set (regno, &set_hash_table);
3499 if (TEST_BIT (cprop_avout[bb], set->bitmap_index))
3501 set = next_set (regno, set);
3507 gcc_assert (GET_CODE (set->expr) == SET);
3509 src = SET_SRC (set->expr);
3510 if (gcse_constant_p (src))
3516 regno = REGNO (src);
3522 /* Subroutine of bypass_block that checks whether a pseudo is killed by
3523 any of the instructions inserted on an edge. Jump bypassing places
3524 condition code setters on CFG edges using insert_insn_on_edge. This
3525 function is required to check that our data flow analysis is still
3526 valid prior to commit_edge_insertions. */
3529 reg_killed_on_edge (const_rtx reg, const_edge e)
3533 for (insn = e->insns.r; insn; insn = NEXT_INSN (insn))
3534 if (INSN_P (insn) && reg_set_p (reg, insn))
3540 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
3541 basic block BB which has more than one predecessor. If not NULL, SETCC
3542 is the first instruction of BB, which is immediately followed by JUMP_INSN
3543 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
3544 Returns nonzero if a change was made.
3546 During the jump bypassing pass, we may place copies of SETCC instructions
3547 on CFG edges. The following routine must be careful to pay attention to
3548 these inserted insns when performing its transformations. */
3551 bypass_block (basic_block bb, rtx setcc, rtx jump)
3556 int may_be_loop_header;
3560 insn = (setcc != NULL) ? setcc : jump;
3562 /* Determine set of register uses in INSN. */
3564 note_uses (&PATTERN (insn), find_used_regs, NULL);
3565 note = find_reg_equal_equiv_note (insn);
3567 find_used_regs (&XEXP (note, 0), NULL);
3569 may_be_loop_header = false;
3570 FOR_EACH_EDGE (e, ei, bb->preds)
3571 if (e->flags & EDGE_DFS_BACK)
3573 may_be_loop_header = true;
3578 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
3582 if (e->flags & EDGE_COMPLEX)
3588 /* We can't redirect edges from new basic blocks. */
3589 if (e->src->index >= bypass_last_basic_block)
3595 /* The irreducible loops created by redirecting of edges entering the
3596 loop from outside would decrease effectiveness of some of the following
3597 optimizations, so prevent this. */
3598 if (may_be_loop_header
3599 && !(e->flags & EDGE_DFS_BACK))
3605 for (i = 0; i < reg_use_count; i++)
3607 struct reg_use *reg_used = ®_use_table[i];
3608 unsigned int regno = REGNO (reg_used->reg_rtx);
3609 basic_block dest, old_dest;
3613 if (regno >= max_gcse_regno)
3616 set = find_bypass_set (regno, e->src->index);
3621 /* Check the data flow is valid after edge insertions. */
3622 if (e->insns.r && reg_killed_on_edge (reg_used->reg_rtx, e))
3625 src = SET_SRC (pc_set (jump));
3628 src = simplify_replace_rtx (src,
3629 SET_DEST (PATTERN (setcc)),
3630 SET_SRC (PATTERN (setcc)));
3632 new = simplify_replace_rtx (src, reg_used->reg_rtx,
3633 SET_SRC (set->expr));
3635 /* Jump bypassing may have already placed instructions on
3636 edges of the CFG. We can't bypass an outgoing edge that
3637 has instructions associated with it, as these insns won't
3638 get executed if the incoming edge is redirected. */
3642 edest = FALLTHRU_EDGE (bb);
3643 dest = edest->insns.r ? NULL : edest->dest;
3645 else if (GET_CODE (new) == LABEL_REF)
3647 dest = BLOCK_FOR_INSN (XEXP (new, 0));
3648 /* Don't bypass edges containing instructions. */
3649 edest = find_edge (bb, dest);
3650 if (edest && edest->insns.r)
3656 /* Avoid unification of the edge with other edges from original
3657 branch. We would end up emitting the instruction on "both"
3660 if (dest && setcc && !CC0_P (SET_DEST (PATTERN (setcc)))
3661 && find_edge (e->src, dest))
3667 && dest != EXIT_BLOCK_PTR)
3669 redirect_edge_and_branch_force (e, dest);
3671 /* Copy the register setter to the redirected edge.
3672 Don't copy CC0 setters, as CC0 is dead after jump. */
3675 rtx pat = PATTERN (setcc);
3676 if (!CC0_P (SET_DEST (pat)))
3677 insert_insn_on_edge (copy_insn (pat), e);
3680 if (dump_file != NULL)
3682 fprintf (dump_file, "JUMP-BYPASS: Proved reg %d "
3683 "in jump_insn %d equals constant ",
3684 regno, INSN_UID (jump));
3685 print_rtl (dump_file, SET_SRC (set->expr));
3686 fprintf (dump_file, "\nBypass edge from %d->%d to %d\n",
3687 e->src->index, old_dest->index, dest->index);
3700 /* Find basic blocks with more than one predecessor that only contain a
3701 single conditional jump. If the result of the comparison is known at
3702 compile-time from any incoming edge, redirect that edge to the
3703 appropriate target. Returns nonzero if a change was made.
3705 This function is now mis-named, because we also handle indirect jumps. */
3708 bypass_conditional_jumps (void)
3716 /* Note we start at block 1. */
3717 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
3720 bypass_last_basic_block = last_basic_block;
3721 mark_dfs_back_edges ();
3724 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb,
3725 EXIT_BLOCK_PTR, next_bb)
3727 /* Check for more than one predecessor. */
3728 if (!single_pred_p (bb))
3731 FOR_BB_INSNS (bb, insn)
3732 if (NONJUMP_INSN_P (insn))
3736 if (GET_CODE (PATTERN (insn)) != SET)
3739 dest = SET_DEST (PATTERN (insn));
3740 if (REG_P (dest) || CC0_P (dest))
3745 else if (JUMP_P (insn))
3747 if ((any_condjump_p (insn) || computed_jump_p (insn))
3748 && onlyjump_p (insn))
3749 changed |= bypass_block (bb, setcc, insn);
3752 else if (INSN_P (insn))
3757 /* If we bypassed any register setting insns, we inserted a
3758 copy on the redirected edge. These need to be committed. */
3760 commit_edge_insertions ();
3765 /* Compute PRE+LCM working variables. */
3767 /* Local properties of expressions. */
3768 /* Nonzero for expressions that are transparent in the block. */
3769 static sbitmap *transp;
3771 /* Nonzero for expressions that are transparent at the end of the block.
3772 This is only zero for expressions killed by abnormal critical edge
3773 created by a calls. */
3774 static sbitmap *transpout;
3776 /* Nonzero for expressions that are computed (available) in the block. */
3777 static sbitmap *comp;
3779 /* Nonzero for expressions that are locally anticipatable in the block. */
3780 static sbitmap *antloc;
3782 /* Nonzero for expressions where this block is an optimal computation
3784 static sbitmap *pre_optimal;
3786 /* Nonzero for expressions which are redundant in a particular block. */
3787 static sbitmap *pre_redundant;
3789 /* Nonzero for expressions which should be inserted on a specific edge. */
3790 static sbitmap *pre_insert_map;
3792 /* Nonzero for expressions which should be deleted in a specific block. */
3793 static sbitmap *pre_delete_map;
3795 /* Contains the edge_list returned by pre_edge_lcm. */
3796 static struct edge_list *edge_list;
3798 /* Redundant insns. */
3799 static sbitmap pre_redundant_insns;
3801 /* Allocate vars used for PRE analysis. */
3804 alloc_pre_mem (int n_blocks, int n_exprs)
3806 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
3807 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
3808 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
3811 pre_redundant = NULL;
3812 pre_insert_map = NULL;
3813 pre_delete_map = NULL;
3814 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
3816 /* pre_insert and pre_delete are allocated later. */
3819 /* Free vars used for PRE analysis. */
3824 sbitmap_vector_free (transp);
3825 sbitmap_vector_free (comp);
3827 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
3830 sbitmap_vector_free (pre_optimal);
3832 sbitmap_vector_free (pre_redundant);
3834 sbitmap_vector_free (pre_insert_map);
3836 sbitmap_vector_free (pre_delete_map);
3838 transp = comp = NULL;
3839 pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
3842 /* Top level routine to do the dataflow analysis needed by PRE. */
3845 compute_pre_data (void)
3847 sbitmap trapping_expr;
3851 compute_local_properties (transp, comp, antloc, &expr_hash_table);
3852 sbitmap_vector_zero (ae_kill, last_basic_block);
3854 /* Collect expressions which might trap. */
3855 trapping_expr = sbitmap_alloc (expr_hash_table.n_elems);
3856 sbitmap_zero (trapping_expr);
3857 for (ui = 0; ui < expr_hash_table.size; ui++)
3860 for (e = expr_hash_table.table[ui]; e != NULL; e = e->next_same_hash)
3861 if (may_trap_p (e->expr))
3862 SET_BIT (trapping_expr, e->bitmap_index);
3865 /* Compute ae_kill for each basic block using:
3875 /* If the current block is the destination of an abnormal edge, we
3876 kill all trapping expressions because we won't be able to properly
3877 place the instruction on the edge. So make them neither
3878 anticipatable nor transparent. This is fairly conservative. */
3879 FOR_EACH_EDGE (e, ei, bb->preds)
3880 if (e->flags & EDGE_ABNORMAL)
3882 sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr);
3883 sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr);
3887 sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]);
3888 sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]);
3891 edge_list = pre_edge_lcm (expr_hash_table.n_elems, transp, comp, antloc,
3892 ae_kill, &pre_insert_map, &pre_delete_map);
3893 sbitmap_vector_free (antloc);
3895 sbitmap_vector_free (ae_kill);
3897 sbitmap_free (trapping_expr);
3902 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
3905 VISITED is a pointer to a working buffer for tracking which BB's have
3906 been visited. It is NULL for the top-level call.
3908 We treat reaching expressions that go through blocks containing the same
3909 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3910 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3911 2 as not reaching. The intent is to improve the probability of finding
3912 only one reaching expression and to reduce register lifetimes by picking
3913 the closest such expression. */
3916 pre_expr_reaches_here_p_work (basic_block occr_bb, struct expr *expr, basic_block bb, char *visited)
3921 FOR_EACH_EDGE (pred, ei, bb->preds)
3923 basic_block pred_bb = pred->src;
3925 if (pred->src == ENTRY_BLOCK_PTR
3926 /* Has predecessor has already been visited? */
3927 || visited[pred_bb->index])
3928 ;/* Nothing to do. */
3930 /* Does this predecessor generate this expression? */
3931 else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
3933 /* Is this the occurrence we're looking for?
3934 Note that there's only one generating occurrence per block
3935 so we just need to check the block number. */
3936 if (occr_bb == pred_bb)
3939 visited[pred_bb->index] = 1;
3941 /* Ignore this predecessor if it kills the expression. */
3942 else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
3943 visited[pred_bb->index] = 1;
3945 /* Neither gen nor kill. */
3948 visited[pred_bb->index] = 1;
3949 if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
3954 /* All paths have been checked. */
3958 /* The wrapper for pre_expr_reaches_here_work that ensures that any
3959 memory allocated for that function is returned. */
3962 pre_expr_reaches_here_p (basic_block occr_bb, struct expr *expr, basic_block bb)
3965 char *visited = XCNEWVEC (char, last_basic_block);
3967 rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited);
3974 /* Given an expr, generate RTL which we can insert at the end of a BB,
3975 or on an edge. Set the block number of any insns generated to
3979 process_insert_insn (struct expr *expr)
3981 rtx reg = expr->reaching_reg;
3982 rtx exp = copy_rtx (expr->expr);
3987 /* If the expression is something that's an operand, like a constant,
3988 just copy it to a register. */
3989 if (general_operand (exp, GET_MODE (reg)))
3990 emit_move_insn (reg, exp);
3992 /* Otherwise, make a new insn to compute this expression and make sure the
3993 insn will be recognized (this also adds any needed CLOBBERs). Copy the
3994 expression to make sure we don't have any sharing issues. */
3997 rtx insn = emit_insn (gen_rtx_SET (VOIDmode, reg, exp));
3999 if (insn_invalid_p (insn))
4010 /* Add EXPR to the end of basic block BB.
4012 This is used by both the PRE and code hoisting.
4014 For PRE, we want to verify that the expr is either transparent
4015 or locally anticipatable in the target block. This check makes
4016 no sense for code hoisting. */
4019 insert_insn_end_basic_block (struct expr *expr, basic_block bb, int pre)
4021 rtx insn = BB_END (bb);
4023 rtx reg = expr->reaching_reg;
4024 int regno = REGNO (reg);
4027 pat = process_insert_insn (expr);
4028 gcc_assert (pat && INSN_P (pat));
4031 while (NEXT_INSN (pat_end) != NULL_RTX)
4032 pat_end = NEXT_INSN (pat_end);
4034 /* If the last insn is a jump, insert EXPR in front [taking care to
4035 handle cc0, etc. properly]. Similarly we need to care trapping
4036 instructions in presence of non-call exceptions. */
4039 || (NONJUMP_INSN_P (insn)
4040 && (!single_succ_p (bb)
4041 || single_succ_edge (bb)->flags & EDGE_ABNORMAL)))
4046 /* It should always be the case that we can put these instructions
4047 anywhere in the basic block with performing PRE optimizations.
4049 gcc_assert (!NONJUMP_INSN_P (insn) || !pre
4050 || TEST_BIT (antloc[bb->index], expr->bitmap_index)
4051 || TEST_BIT (transp[bb->index], expr->bitmap_index));
4053 /* If this is a jump table, then we can't insert stuff here. Since
4054 we know the previous real insn must be the tablejump, we insert
4055 the new instruction just before the tablejump. */
4056 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
4057 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
4058 insn = prev_real_insn (insn);
4061 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4062 if cc0 isn't set. */
4063 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
4065 insn = XEXP (note, 0);
4068 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
4069 if (maybe_cc0_setter
4070 && INSN_P (maybe_cc0_setter)
4071 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
4072 insn = maybe_cc0_setter;
4075 /* FIXME: What if something in cc0/jump uses value set in new insn? */
4076 new_insn = emit_insn_before_noloc (pat, insn, bb);
4079 /* Likewise if the last insn is a call, as will happen in the presence
4080 of exception handling. */
4081 else if (CALL_P (insn)
4082 && (!single_succ_p (bb)
4083 || single_succ_edge (bb)->flags & EDGE_ABNORMAL))
4085 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
4086 we search backward and place the instructions before the first
4087 parameter is loaded. Do this for everyone for consistency and a
4088 presumption that we'll get better code elsewhere as well.
4090 It should always be the case that we can put these instructions
4091 anywhere in the basic block with performing PRE optimizations.
4095 || TEST_BIT (antloc[bb->index], expr->bitmap_index)
4096 || TEST_BIT (transp[bb->index], expr->bitmap_index));
4098 /* Since different machines initialize their parameter registers
4099 in different orders, assume nothing. Collect the set of all
4100 parameter registers. */
4101 insn = find_first_parameter_load (insn, BB_HEAD (bb));
4103 /* If we found all the parameter loads, then we want to insert
4104 before the first parameter load.
4106 If we did not find all the parameter loads, then we might have
4107 stopped on the head of the block, which could be a CODE_LABEL.
4108 If we inserted before the CODE_LABEL, then we would be putting
4109 the insn in the wrong basic block. In that case, put the insn
4110 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
4111 while (LABEL_P (insn)
4112 || NOTE_INSN_BASIC_BLOCK_P (insn))
4113 insn = NEXT_INSN (insn);
4115 new_insn = emit_insn_before_noloc (pat, insn, bb);
4118 new_insn = emit_insn_after_noloc (pat, insn, bb);
4124 add_label_notes (PATTERN (pat), new_insn);
4125 note_stores (PATTERN (pat), record_set_info, pat);
4129 pat = NEXT_INSN (pat);
4132 gcse_create_count++;
4136 fprintf (dump_file, "PRE/HOIST: end of bb %d, insn %d, ",
4137 bb->index, INSN_UID (new_insn));
4138 fprintf (dump_file, "copying expression %d to reg %d\n",
4139 expr->bitmap_index, regno);
4143 /* Insert partially redundant expressions on edges in the CFG to make
4144 the expressions fully redundant. */
4147 pre_edge_insert (struct edge_list *edge_list, struct expr **index_map)
4149 int e, i, j, num_edges, set_size, did_insert = 0;
4152 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
4153 if it reaches any of the deleted expressions. */
4155 set_size = pre_insert_map[0]->size;
4156 num_edges = NUM_EDGES (edge_list);
4157 inserted = sbitmap_vector_alloc (num_edges, expr_hash_table.n_elems);
4158 sbitmap_vector_zero (inserted, num_edges);
4160 for (e = 0; e < num_edges; e++)
4163 basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
4165 for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
4167 SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
4169 for (j = indx; insert && j < (int) expr_hash_table.n_elems; j++, insert >>= 1)
4170 if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
4172 struct expr *expr = index_map[j];
4175 /* Now look at each deleted occurrence of this expression. */
4176 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4178 if (! occr->deleted_p)
4181 /* Insert this expression on this edge if it would
4182 reach the deleted occurrence in BB. */
4183 if (!TEST_BIT (inserted[e], j))
4186 edge eg = INDEX_EDGE (edge_list, e);
4188 /* We can't insert anything on an abnormal and
4189 critical edge, so we insert the insn at the end of
4190 the previous block. There are several alternatives
4191 detailed in Morgans book P277 (sec 10.5) for
4192 handling this situation. This one is easiest for
4195 if (eg->flags & EDGE_ABNORMAL)
4196 insert_insn_end_basic_block (index_map[j], bb, 0);
4199 insn = process_insert_insn (index_map[j]);
4200 insert_insn_on_edge (insn, eg);
4205 fprintf (dump_file, "PRE/HOIST: edge (%d,%d), ",
4207 INDEX_EDGE_SUCC_BB (edge_list, e)->index);
4208 fprintf (dump_file, "copy expression %d\n",
4209 expr->bitmap_index);
4212 update_ld_motion_stores (expr);
4213 SET_BIT (inserted[e], j);
4215 gcse_create_count++;
4222 sbitmap_vector_free (inserted);
4226 /* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
4227 Given "old_reg <- expr" (INSN), instead of adding after it
4228 reaching_reg <- old_reg
4229 it's better to do the following:
4230 reaching_reg <- expr
4231 old_reg <- reaching_reg
4232 because this way copy propagation can discover additional PRE
4233 opportunities. But if this fails, we try the old way.
4234 When "expr" is a store, i.e.
4235 given "MEM <- old_reg", instead of adding after it
4236 reaching_reg <- old_reg
4237 it's better to add it before as follows:
4238 reaching_reg <- old_reg
4239 MEM <- reaching_reg. */
4242 pre_insert_copy_insn (struct expr *expr, rtx insn)
4244 rtx reg = expr->reaching_reg;
4245 int regno = REGNO (reg);
4246 int indx = expr->bitmap_index;
4247 rtx pat = PATTERN (insn);
4248 rtx set, first_set, new_insn;
4252 /* This block matches the logic in hash_scan_insn. */
4253 switch (GET_CODE (pat))
4260 /* Search through the parallel looking for the set whose
4261 source was the expression that we're interested in. */
4262 first_set = NULL_RTX;
4264 for (i = 0; i < XVECLEN (pat, 0); i++)
4266 rtx x = XVECEXP (pat, 0, i);
4267 if (GET_CODE (x) == SET)
4269 /* If the source was a REG_EQUAL or REG_EQUIV note, we
4270 may not find an equivalent expression, but in this
4271 case the PARALLEL will have a single set. */
4272 if (first_set == NULL_RTX)
4274 if (expr_equiv_p (SET_SRC (x), expr->expr))
4282 gcc_assert (first_set);
4283 if (set == NULL_RTX)
4291 if (REG_P (SET_DEST (set)))
4293 old_reg = SET_DEST (set);
4294 /* Check if we can modify the set destination in the original insn. */
4295 if (validate_change (insn, &SET_DEST (set), reg, 0))
4297 new_insn = gen_move_insn (old_reg, reg);
4298 new_insn = emit_insn_after (new_insn, insn);
4300 /* Keep register set table up to date. */
4301 record_one_set (regno, insn);
4305 new_insn = gen_move_insn (reg, old_reg);
4306 new_insn = emit_insn_after (new_insn, insn);
4308 /* Keep register set table up to date. */
4309 record_one_set (regno, new_insn);
4312 else /* This is possible only in case of a store to memory. */
4314 old_reg = SET_SRC (set);
4315 new_insn = gen_move_insn (reg, old_reg);
4317 /* Check if we can modify the set source in the original insn. */
4318 if (validate_change (insn, &SET_SRC (set), reg, 0))
4319 new_insn = emit_insn_before (new_insn, insn);
4321 new_insn = emit_insn_after (new_insn, insn);
4323 /* Keep register set table up to date. */
4324 record_one_set (regno, new_insn);
4327 gcse_create_count++;
4331 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
4332 BLOCK_NUM (insn), INSN_UID (new_insn), indx,
4333 INSN_UID (insn), regno);
4336 /* Copy available expressions that reach the redundant expression
4337 to `reaching_reg'. */
4340 pre_insert_copies (void)
4342 unsigned int i, added_copy;
4347 /* For each available expression in the table, copy the result to
4348 `reaching_reg' if the expression reaches a deleted one.
4350 ??? The current algorithm is rather brute force.
4351 Need to do some profiling. */
4353 for (i = 0; i < expr_hash_table.size; i++)
4354 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
4356 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
4357 we don't want to insert a copy here because the expression may not
4358 really be redundant. So only insert an insn if the expression was
4359 deleted. This test also avoids further processing if the
4360 expression wasn't deleted anywhere. */
4361 if (expr->reaching_reg == NULL)
4364 /* Set when we add a copy for that expression. */
4367 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4369 if (! occr->deleted_p)
4372 for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
4374 rtx insn = avail->insn;
4376 /* No need to handle this one if handled already. */
4377 if (avail->copied_p)
4380 /* Don't handle this one if it's a redundant one. */
4381 if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
4384 /* Or if the expression doesn't reach the deleted one. */
4385 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
4387 BLOCK_FOR_INSN (occr->insn)))
4392 /* Copy the result of avail to reaching_reg. */
4393 pre_insert_copy_insn (expr, insn);
4394 avail->copied_p = 1;
4399 update_ld_motion_stores (expr);
4403 /* Emit move from SRC to DEST noting the equivalence with expression computed
4406 gcse_emit_move_after (rtx src, rtx dest, rtx insn)
4409 rtx set = single_set (insn), set2;
4413 /* This should never fail since we're creating a reg->reg copy
4414 we've verified to be valid. */
4416 new = emit_insn_after (gen_move_insn (dest, src), insn);
4418 /* Note the equivalence for local CSE pass. */
4419 set2 = single_set (new);
4420 if (!set2 || !rtx_equal_p (SET_DEST (set2), dest))
4422 if ((note = find_reg_equal_equiv_note (insn)))
4423 eqv = XEXP (note, 0);
4425 eqv = SET_SRC (set);
4427 set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (eqv));
4432 /* Delete redundant computations.
4433 Deletion is done by changing the insn to copy the `reaching_reg' of
4434 the expression into the result of the SET. It is left to later passes
4435 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
4437 Returns nonzero if a change is made. */
4448 for (i = 0; i < expr_hash_table.size; i++)
4449 for (expr = expr_hash_table.table[i];
4451 expr = expr->next_same_hash)
4453 int indx = expr->bitmap_index;
4455 /* We only need to search antic_occr since we require
4458 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4460 rtx insn = occr->insn;
4462 basic_block bb = BLOCK_FOR_INSN (insn);
4464 /* We only delete insns that have a single_set. */
4465 if (TEST_BIT (pre_delete_map[bb->index], indx)
4466 && (set = single_set (insn)) != 0
4467 && dbg_cnt (pre_insn))
4469 /* Create a pseudo-reg to store the result of reaching
4470 expressions into. Get the mode for the new pseudo from
4471 the mode of the original destination pseudo. */
4472 if (expr->reaching_reg == NULL)
4474 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
4476 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
4478 occr->deleted_p = 1;
4479 SET_BIT (pre_redundant_insns, INSN_CUID (insn));
4486 "PRE: redundant insn %d (expression %d) in ",
4487 INSN_UID (insn), indx);
4488 fprintf (dump_file, "bb %d, reaching reg is %d\n",
4489 bb->index, REGNO (expr->reaching_reg));
4498 /* Perform GCSE optimizations using PRE.
4499 This is called by one_pre_gcse_pass after all the dataflow analysis
4502 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
4503 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
4504 Compiler Design and Implementation.
4506 ??? A new pseudo reg is created to hold the reaching expression. The nice
4507 thing about the classical approach is that it would try to use an existing
4508 reg. If the register can't be adequately optimized [i.e. we introduce
4509 reload problems], one could add a pass here to propagate the new register
4512 ??? We don't handle single sets in PARALLELs because we're [currently] not
4513 able to copy the rest of the parallel when we insert copies to create full
4514 redundancies from partial redundancies. However, there's no reason why we
4515 can't handle PARALLELs in the cases where there are no partial
4522 int did_insert, changed;
4523 struct expr **index_map;
4526 /* Compute a mapping from expression number (`bitmap_index') to
4527 hash table entry. */
4529 index_map = XCNEWVEC (struct expr *, expr_hash_table.n_elems);
4530 for (i = 0; i < expr_hash_table.size; i++)
4531 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
4532 index_map[expr->bitmap_index] = expr;
4534 /* Reset bitmap used to track which insns are redundant. */
4535 pre_redundant_insns = sbitmap_alloc (max_cuid);
4536 sbitmap_zero (pre_redundant_insns);
4538 /* Delete the redundant insns first so that
4539 - we know what register to use for the new insns and for the other
4540 ones with reaching expressions
4541 - we know which insns are redundant when we go to create copies */
4543 changed = pre_delete ();
4544 did_insert = pre_edge_insert (edge_list, index_map);
4546 /* In other places with reaching expressions, copy the expression to the
4547 specially allocated pseudo-reg that reaches the redundant expr. */
4548 pre_insert_copies ();
4551 commit_edge_insertions ();
4556 sbitmap_free (pre_redundant_insns);
4560 /* Top level routine to perform one PRE GCSE pass.
4562 Return nonzero if a change was made. */
4565 one_pre_gcse_pass (int pass)
4569 gcse_subst_count = 0;
4570 gcse_create_count = 0;
4572 alloc_hash_table (max_cuid, &expr_hash_table, 0);
4573 add_noreturn_fake_exit_edges ();
4575 compute_ld_motion_mems ();
4577 compute_hash_table (&expr_hash_table);
4578 trim_ld_motion_mems ();
4580 dump_hash_table (dump_file, "Expression", &expr_hash_table);
4582 if (expr_hash_table.n_elems > 0)
4584 alloc_pre_mem (last_basic_block, expr_hash_table.n_elems);
4585 compute_pre_data ();
4586 changed |= pre_gcse ();
4587 free_edge_list (edge_list);
4592 remove_fake_exit_edges ();
4593 free_hash_table (&expr_hash_table);
4597 fprintf (dump_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
4598 current_function_name (), pass, bytes_used);
4599 fprintf (dump_file, "%d substs, %d insns created\n",
4600 gcse_subst_count, gcse_create_count);
4606 /* If X contains any LABEL_REF's, add REG_LABEL_OPERAND notes for them
4607 to INSN. If such notes are added to an insn which references a
4608 CODE_LABEL, the LABEL_NUSES count is incremented. We have to add
4609 that note, because the following loop optimization pass requires
4612 /* ??? If there was a jump optimization pass after gcse and before loop,
4613 then we would not need to do this here, because jump would add the
4614 necessary REG_LABEL_OPERAND and REG_LABEL_TARGET notes. */
4617 add_label_notes (rtx x, rtx insn)
4619 enum rtx_code code = GET_CODE (x);
4623 if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
4625 /* This code used to ignore labels that referred to dispatch tables to
4626 avoid flow generating (slightly) worse code.
4628 We no longer ignore such label references (see LABEL_REF handling in
4629 mark_jump_label for additional information). */
4631 if (reg_mentioned_p (XEXP (x, 0), insn))
4633 /* There's no reason for current users to emit jump-insns
4634 with such a LABEL_REF, so we don't have to handle
4635 REG_LABEL_TARGET notes. */
4636 gcc_assert (!JUMP_P (insn));
4638 = gen_rtx_INSN_LIST (REG_LABEL_OPERAND, XEXP (x, 0),
4640 if (LABEL_P (XEXP (x, 0)))
4641 LABEL_NUSES (XEXP (x, 0))++;
4646 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
4649 add_label_notes (XEXP (x, i), insn);
4650 else if (fmt[i] == 'E')
4651 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4652 add_label_notes (XVECEXP (x, i, j), insn);
4656 /* Compute transparent outgoing information for each block.
4658 An expression is transparent to an edge unless it is killed by
4659 the edge itself. This can only happen with abnormal control flow,
4660 when the edge is traversed through a call. This happens with
4661 non-local labels and exceptions.
4663 This would not be necessary if we split the edge. While this is
4664 normally impossible for abnormal critical edges, with some effort
4665 it should be possible with exception handling, since we still have
4666 control over which handler should be invoked. But due to increased
4667 EH table sizes, this may not be worthwhile. */
4670 compute_transpout (void)
4676 sbitmap_vector_ones (transpout, last_basic_block);
4680 /* Note that flow inserted a nop a the end of basic blocks that
4681 end in call instructions for reasons other than abnormal
4683 if (! CALL_P (BB_END (bb)))
4686 for (i = 0; i < expr_hash_table.size; i++)
4687 for (expr = expr_hash_table.table[i]; expr ; expr = expr->next_same_hash)
4688 if (MEM_P (expr->expr))
4690 if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
4691 && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
4694 /* ??? Optimally, we would use interprocedural alias
4695 analysis to determine if this mem is actually killed
4697 RESET_BIT (transpout[bb->index], expr->bitmap_index);
4702 /* Code Hoisting variables and subroutines. */
4704 /* Very busy expressions. */
4705 static sbitmap *hoist_vbein;
4706 static sbitmap *hoist_vbeout;
4708 /* Hoistable expressions. */
4709 static sbitmap *hoist_exprs;
4711 /* ??? We could compute post dominators and run this algorithm in
4712 reverse to perform tail merging, doing so would probably be
4713 more effective than the tail merging code in jump.c.
4715 It's unclear if tail merging could be run in parallel with
4716 code hoisting. It would be nice. */
4718 /* Allocate vars used for code hoisting analysis. */
4721 alloc_code_hoist_mem (int n_blocks, int n_exprs)
4723 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
4724 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
4725 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
4727 hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
4728 hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
4729 hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
4730 transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
4733 /* Free vars used for code hoisting analysis. */
4736 free_code_hoist_mem (void)
4738 sbitmap_vector_free (antloc);
4739 sbitmap_vector_free (transp);
4740 sbitmap_vector_free (comp);
4742 sbitmap_vector_free (hoist_vbein);
4743 sbitmap_vector_free (hoist_vbeout);
4744 sbitmap_vector_free (hoist_exprs);
4745 sbitmap_vector_free (transpout);
4747 free_dominance_info (CDI_DOMINATORS);
4750 /* Compute the very busy expressions at entry/exit from each block.
4752 An expression is very busy if all paths from a given point
4753 compute the expression. */
4756 compute_code_hoist_vbeinout (void)
4758 int changed, passes;
4761 sbitmap_vector_zero (hoist_vbeout, last_basic_block);
4762 sbitmap_vector_zero (hoist_vbein, last_basic_block);
4771 /* We scan the blocks in the reverse order to speed up
4773 FOR_EACH_BB_REVERSE (bb)
4775 changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index], antloc[bb->index],
4776 hoist_vbeout[bb->index], transp[bb->index]);
4777 if (bb->next_bb != EXIT_BLOCK_PTR)
4778 sbitmap_intersection_of_succs (hoist_vbeout[bb->index], hoist_vbein, bb->index);
4785 fprintf (dump_file, "hoisting vbeinout computation: %d passes\n", passes);
4788 /* Top level routine to do the dataflow analysis needed by code hoisting. */
4791 compute_code_hoist_data (void)
4793 compute_local_properties (transp, comp, antloc, &expr_hash_table);
4794 compute_transpout ();
4795 compute_code_hoist_vbeinout ();
4796 calculate_dominance_info (CDI_DOMINATORS);
4798 fprintf (dump_file, "\n");
4801 /* Determine if the expression identified by EXPR_INDEX would
4802 reach BB unimpared if it was placed at the end of EXPR_BB.
4804 It's unclear exactly what Muchnick meant by "unimpared". It seems
4805 to me that the expression must either be computed or transparent in
4806 *every* block in the path(s) from EXPR_BB to BB. Any other definition
4807 would allow the expression to be hoisted out of loops, even if
4808 the expression wasn't a loop invariant.
4810 Contrast this to reachability for PRE where an expression is
4811 considered reachable if *any* path reaches instead of *all*
4815 hoist_expr_reaches_here_p (basic_block expr_bb, int expr_index, basic_block bb, char *visited)
4819 int visited_allocated_locally = 0;
4822 if (visited == NULL)
4824 visited_allocated_locally = 1;
4825 visited = XCNEWVEC (char, last_basic_block);
4828 FOR_EACH_EDGE (pred, ei, bb->preds)
4830 basic_block pred_bb = pred->src;
4832 if (pred->src == ENTRY_BLOCK_PTR)
4834 else if (pred_bb == expr_bb)
4836 else if (visited[pred_bb->index])
4839 /* Does this predecessor generate this expression? */
4840 else if (TEST_BIT (comp[pred_bb->index], expr_index))
4842 else if (! TEST_BIT (transp[pred_bb->index], expr_index))
4848 visited[pred_bb->index] = 1;
4849 if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
4854 if (visited_allocated_locally)
4857 return (pred == NULL);
4860 /* Actually perform code hoisting. */
4865 basic_block bb, dominated;
4866 VEC (basic_block, heap) *domby;
4868 struct expr **index_map;
4871 sbitmap_vector_zero (hoist_exprs, last_basic_block);
4873 /* Compute a mapping from expression number (`bitmap_index') to
4874 hash table entry. */
4876 index_map = XCNEWVEC (struct expr *, expr_hash_table.n_elems);
4877 for (i = 0; i < expr_hash_table.size; i++)
4878 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
4879 index_map[expr->bitmap_index] = expr;
4881 /* Walk over each basic block looking for potentially hoistable
4882 expressions, nothing gets hoisted from the entry block. */
4886 int insn_inserted_p;
4888 domby = get_dominated_by (CDI_DOMINATORS, bb);
4889 /* Examine each expression that is very busy at the exit of this
4890 block. These are the potentially hoistable expressions. */
4891 for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++)
4895 if (TEST_BIT (hoist_vbeout[bb->index], i)
4896 && TEST_BIT (transpout[bb->index], i))
4898 /* We've found a potentially hoistable expression, now
4899 we look at every block BB dominates to see if it
4900 computes the expression. */
4901 for (j = 0; VEC_iterate (basic_block, domby, j, dominated); j++)
4903 /* Ignore self dominance. */
4904 if (bb == dominated)
4906 /* We've found a dominated block, now see if it computes
4907 the busy expression and whether or not moving that
4908 expression to the "beginning" of that block is safe. */
4909 if (!TEST_BIT (antloc[dominated->index], i))
4912 /* Note if the expression would reach the dominated block
4913 unimpared if it was placed at the end of BB.
4915 Keep track of how many times this expression is hoistable
4916 from a dominated block into BB. */
4917 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
4921 /* If we found more than one hoistable occurrence of this
4922 expression, then note it in the bitmap of expressions to
4923 hoist. It makes no sense to hoist things which are computed
4924 in only one BB, and doing so tends to pessimize register
4925 allocation. One could increase this value to try harder
4926 to avoid any possible code expansion due to register
4927 allocation issues; however experiments have shown that
4928 the vast majority of hoistable expressions are only movable
4929 from two successors, so raising this threshold is likely
4930 to nullify any benefit we get from code hoisting. */
4933 SET_BIT (hoist_exprs[bb->index], i);
4938 /* If we found nothing to hoist, then quit now. */
4941 VEC_free (basic_block, heap, domby);
4945 /* Loop over all the hoistable expressions. */
4946 for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++)
4948 /* We want to insert the expression into BB only once, so
4949 note when we've inserted it. */
4950 insn_inserted_p = 0;
4952 /* These tests should be the same as the tests above. */
4953 if (TEST_BIT (hoist_exprs[bb->index], i))
4955 /* We've found a potentially hoistable expression, now
4956 we look at every block BB dominates to see if it
4957 computes the expression. */
4958 for (j = 0; VEC_iterate (basic_block, domby, j, dominated); j++)
4960 /* Ignore self dominance. */
4961 if (bb == dominated)
4964 /* We've found a dominated block, now see if it computes
4965 the busy expression and whether or not moving that
4966 expression to the "beginning" of that block is safe. */
4967 if (!TEST_BIT (antloc[dominated->index], i))
4970 /* The expression is computed in the dominated block and
4971 it would be safe to compute it at the start of the
4972 dominated block. Now we have to determine if the
4973 expression would reach the dominated block if it was
4974 placed at the end of BB. */
4975 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
4977 struct expr *expr = index_map[i];
4978 struct occr *occr = expr->antic_occr;
4982 /* Find the right occurrence of this expression. */
4983 while (BLOCK_FOR_INSN (occr->insn) != dominated && occr)
4988 set = single_set (insn);
4991 /* Create a pseudo-reg to store the result of reaching
4992 expressions into. Get the mode for the new pseudo
4993 from the mode of the original destination pseudo. */
4994 if (expr->reaching_reg == NULL)
4996 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
4998 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
5000 occr->deleted_p = 1;
5001 if (!insn_inserted_p)
5003 insert_insn_end_basic_block (index_map[i], bb, 0);
5004 insn_inserted_p = 1;
5010 VEC_free (basic_block, heap, domby);
5016 /* Top level routine to perform one code hoisting (aka unification) pass
5018 Return nonzero if a change was made. */
5021 one_code_hoisting_pass (void)
5025 alloc_hash_table (max_cuid, &expr_hash_table, 0);
5026 compute_hash_table (&expr_hash_table);
5028 dump_hash_table (dump_file, "Code Hosting Expressions", &expr_hash_table);
5030 if (expr_hash_table.n_elems > 0)
5032 alloc_code_hoist_mem (last_basic_block, expr_hash_table.n_elems);
5033 compute_code_hoist_data ();
5035 free_code_hoist_mem ();
5038 free_hash_table (&expr_hash_table);
5043 /* Here we provide the things required to do store motion towards
5044 the exit. In order for this to be effective, gcse also needed to
5045 be taught how to move a load when it is kill only by a store to itself.
5050 void foo(float scale)
5052 for (i=0; i<10; i++)
5056 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
5057 the load out since its live around the loop, and stored at the bottom
5060 The 'Load Motion' referred to and implemented in this file is
5061 an enhancement to gcse which when using edge based lcm, recognizes
5062 this situation and allows gcse to move the load out of the loop.
5064 Once gcse has hoisted the load, store motion can then push this
5065 load towards the exit, and we end up with no loads or stores of 'i'
5069 pre_ldst_expr_hash (const void *p)
5071 int do_not_record_p = 0;
5072 const struct ls_expr *x = p;
5073 return hash_rtx (x->pattern, GET_MODE (x->pattern), &do_not_record_p, NULL, false);
5077 pre_ldst_expr_eq (const void *p1, const void *p2)
5079 const struct ls_expr *ptr1 = p1, *ptr2 = p2;
5080 return expr_equiv_p (ptr1->pattern, ptr2->pattern);
5083 /* This will search the ldst list for a matching expression. If it
5084 doesn't find one, we create one and initialize it. */
5086 static struct ls_expr *
5089 int do_not_record_p = 0;
5090 struct ls_expr * ptr;
5095 hash = hash_rtx (x, GET_MODE (x), &do_not_record_p,
5096 NULL, /*have_reg_qty=*/false);
5099 slot = htab_find_slot_with_hash (pre_ldst_table, &e, hash, INSERT);
5101 return (struct ls_expr *)*slot;
5103 ptr = XNEW (struct ls_expr);
5105 ptr->next = pre_ldst_mems;
5108 ptr->pattern_regs = NULL_RTX;
5109 ptr->loads = NULL_RTX;
5110 ptr->stores = NULL_RTX;
5111 ptr->reaching_reg = NULL_RTX;
5114 ptr->hash_index = hash;
5115 pre_ldst_mems = ptr;
5121 /* Free up an individual ldst entry. */
5124 free_ldst_entry (struct ls_expr * ptr)
5126 free_INSN_LIST_list (& ptr->loads);
5127 free_INSN_LIST_list (& ptr->stores);
5132 /* Free up all memory associated with the ldst list. */
5135 free_ldst_mems (void)
5138 htab_delete (pre_ldst_table);
5139 pre_ldst_table = NULL;
5141 while (pre_ldst_mems)
5143 struct ls_expr * tmp = pre_ldst_mems;
5145 pre_ldst_mems = pre_ldst_mems->next;
5147 free_ldst_entry (tmp);
5150 pre_ldst_mems = NULL;
5153 /* Dump debugging info about the ldst list. */
5156 print_ldst_list (FILE * file)
5158 struct ls_expr * ptr;
5160 fprintf (file, "LDST list: \n");
5162 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
5164 fprintf (file, " Pattern (%3d): ", ptr->index);
5166 print_rtl (file, ptr->pattern);
5168 fprintf (file, "\n Loads : ");
5171 print_rtl (file, ptr->loads);
5173 fprintf (file, "(nil)");
5175 fprintf (file, "\n Stores : ");
5178 print_rtl (file, ptr->stores);
5180 fprintf (file, "(nil)");
5182 fprintf (file, "\n\n");
5185 fprintf (file, "\n");
5188 /* Returns 1 if X is in the list of ldst only expressions. */
5190 static struct ls_expr *
5191 find_rtx_in_ldst (rtx x)
5195 if (!pre_ldst_table)
5198 slot = htab_find_slot (pre_ldst_table, &e, NO_INSERT);
5199 if (!slot || ((struct ls_expr *)*slot)->invalid)
5204 /* Assign each element of the list of mems a monotonically increasing value. */
5207 enumerate_ldsts (void)
5209 struct ls_expr * ptr;
5212 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
5218 /* Return first item in the list. */
5220 static inline struct ls_expr *
5221 first_ls_expr (void)
5223 return pre_ldst_mems;
5226 /* Return the next item in the list after the specified one. */
5228 static inline struct ls_expr *
5229 next_ls_expr (struct ls_expr * ptr)
5234 /* Load Motion for loads which only kill themselves. */
5236 /* Return true if x is a simple MEM operation, with no registers or
5237 side effects. These are the types of loads we consider for the
5238 ld_motion list, otherwise we let the usual aliasing take care of it. */
5241 simple_mem (const_rtx x)
5246 if (MEM_VOLATILE_P (x))
5249 if (GET_MODE (x) == BLKmode)
5252 /* If we are handling exceptions, we must be careful with memory references
5253 that may trap. If we are not, the behavior is undefined, so we may just
5255 if (flag_non_call_exceptions && may_trap_p (x))
5258 if (side_effects_p (x))
5261 /* Do not consider function arguments passed on stack. */
5262 if (reg_mentioned_p (stack_pointer_rtx, x))
5265 if (flag_float_store && FLOAT_MODE_P (GET_MODE (x)))
5271 /* Make sure there isn't a buried reference in this pattern anywhere.
5272 If there is, invalidate the entry for it since we're not capable
5273 of fixing it up just yet.. We have to be sure we know about ALL
5274 loads since the aliasing code will allow all entries in the
5275 ld_motion list to not-alias itself. If we miss a load, we will get
5276 the wrong value since gcse might common it and we won't know to
5280 invalidate_any_buried_refs (rtx x)
5284 struct ls_expr * ptr;
5286 /* Invalidate it in the list. */
5287 if (MEM_P (x) && simple_mem (x))
5289 ptr = ldst_entry (x);
5293 /* Recursively process the insn. */
5294 fmt = GET_RTX_FORMAT (GET_CODE (x));
5296 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
5299 invalidate_any_buried_refs (XEXP (x, i));
5300 else if (fmt[i] == 'E')
5301 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5302 invalidate_any_buried_refs (XVECEXP (x, i, j));
5306 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
5307 being defined as MEM loads and stores to symbols, with no side effects
5308 and no registers in the expression. For a MEM destination, we also
5309 check that the insn is still valid if we replace the destination with a
5310 REG, as is done in update_ld_motion_stores. If there are any uses/defs
5311 which don't match this criteria, they are invalidated and trimmed out
5315 compute_ld_motion_mems (void)
5317 struct ls_expr * ptr;
5321 pre_ldst_mems = NULL;
5322 pre_ldst_table = htab_create (13, pre_ldst_expr_hash,
5323 pre_ldst_expr_eq, NULL);
5327 FOR_BB_INSNS (bb, insn)
5331 if (GET_CODE (PATTERN (insn)) == SET)
5333 rtx src = SET_SRC (PATTERN (insn));
5334 rtx dest = SET_DEST (PATTERN (insn));
5336 /* Check for a simple LOAD... */
5337 if (MEM_P (src) && simple_mem (src))
5339 ptr = ldst_entry (src);
5341 ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
5347 /* Make sure there isn't a buried load somewhere. */
5348 invalidate_any_buried_refs (src);
5351 /* Check for stores. Don't worry about aliased ones, they
5352 will block any movement we might do later. We only care
5353 about this exact pattern since those are the only
5354 circumstance that we will ignore the aliasing info. */
5355 if (MEM_P (dest) && simple_mem (dest))
5357 ptr = ldst_entry (dest);
5360 && GET_CODE (src) != ASM_OPERANDS
5361 /* Check for REG manually since want_to_gcse_p
5362 returns 0 for all REGs. */
5363 && can_assign_to_reg_p (src))
5364 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
5370 invalidate_any_buried_refs (PATTERN (insn));
5376 /* Remove any references that have been either invalidated or are not in the
5377 expression list for pre gcse. */
5380 trim_ld_motion_mems (void)
5382 struct ls_expr * * last = & pre_ldst_mems;
5383 struct ls_expr * ptr = pre_ldst_mems;
5389 /* Delete if entry has been made invalid. */
5392 /* Delete if we cannot find this mem in the expression list. */
5393 unsigned int hash = ptr->hash_index % expr_hash_table.size;
5395 for (expr = expr_hash_table.table[hash];
5397 expr = expr->next_same_hash)
5398 if (expr_equiv_p (expr->expr, ptr->pattern))
5402 expr = (struct expr *) 0;
5406 /* Set the expression field if we are keeping it. */
5414 htab_remove_elt_with_hash (pre_ldst_table, ptr, ptr->hash_index);
5415 free_ldst_entry (ptr);
5420 /* Show the world what we've found. */
5421 if (dump_file && pre_ldst_mems != NULL)
5422 print_ldst_list (dump_file);
5425 /* This routine will take an expression which we are replacing with
5426 a reaching register, and update any stores that are needed if
5427 that expression is in the ld_motion list. Stores are updated by
5428 copying their SRC to the reaching register, and then storing
5429 the reaching register into the store location. These keeps the
5430 correct value in the reaching register for the loads. */
5433 update_ld_motion_stores (struct expr * expr)
5435 struct ls_expr * mem_ptr;
5437 if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
5439 /* We can try to find just the REACHED stores, but is shouldn't
5440 matter to set the reaching reg everywhere... some might be
5441 dead and should be eliminated later. */
5443 /* We replace (set mem expr) with (set reg expr) (set mem reg)
5444 where reg is the reaching reg used in the load. We checked in
5445 compute_ld_motion_mems that we can replace (set mem expr) with
5446 (set reg expr) in that insn. */
5447 rtx list = mem_ptr->stores;
5449 for ( ; list != NULL_RTX; list = XEXP (list, 1))
5451 rtx insn = XEXP (list, 0);
5452 rtx pat = PATTERN (insn);
5453 rtx src = SET_SRC (pat);
5454 rtx reg = expr->reaching_reg;
5457 /* If we've already copied it, continue. */
5458 if (expr->reaching_reg == src)
5463 fprintf (dump_file, "PRE: store updated with reaching reg ");
5464 print_rtl (dump_file, expr->reaching_reg);
5465 fprintf (dump_file, ":\n ");
5466 print_inline_rtx (dump_file, insn, 8);
5467 fprintf (dump_file, "\n");
5470 copy = gen_move_insn ( reg, copy_rtx (SET_SRC (pat)));
5471 new = emit_insn_before (copy, insn);
5472 record_one_set (REGNO (reg), new);
5473 SET_SRC (pat) = reg;
5474 df_insn_rescan (insn);
5476 /* un-recognize this pattern since it's probably different now. */
5477 INSN_CODE (insn) = -1;
5478 gcse_create_count++;
5483 /* Store motion code. */
5485 #define ANTIC_STORE_LIST(x) ((x)->loads)
5486 #define AVAIL_STORE_LIST(x) ((x)->stores)
5487 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
5489 /* This is used to communicate the target bitvector we want to use in the
5490 reg_set_info routine when called via the note_stores mechanism. */
5491 static int * regvec;
5493 /* And current insn, for the same routine. */
5494 static rtx compute_store_table_current_insn;
5496 /* Used in computing the reverse edge graph bit vectors. */
5497 static sbitmap * st_antloc;
5499 /* Global holding the number of store expressions we are dealing with. */
5500 static int num_stores;
5502 /* Checks to set if we need to mark a register set. Called from
5506 reg_set_info (rtx dest, const_rtx setter ATTRIBUTE_UNUSED,
5509 sbitmap bb_reg = data;
5511 if (GET_CODE (dest) == SUBREG)
5512 dest = SUBREG_REG (dest);
5516 regvec[REGNO (dest)] = INSN_UID (compute_store_table_current_insn);
5518 SET_BIT (bb_reg, REGNO (dest));
5522 /* Clear any mark that says that this insn sets dest. Called from
5526 reg_clear_last_set (rtx dest, const_rtx setter ATTRIBUTE_UNUSED,
5529 int *dead_vec = data;
5531 if (GET_CODE (dest) == SUBREG)
5532 dest = SUBREG_REG (dest);
5535 dead_vec[REGNO (dest)] == INSN_UID (compute_store_table_current_insn))
5536 dead_vec[REGNO (dest)] = 0;
5539 /* Return zero if some of the registers in list X are killed
5540 due to set of registers in bitmap REGS_SET. */
5543 store_ops_ok (const_rtx x, int *regs_set)
5547 for (; x; x = XEXP (x, 1))
5550 if (regs_set[REGNO(reg)])
5557 /* Returns a list of registers mentioned in X. */
5559 extract_mentioned_regs (rtx x)
5561 return extract_mentioned_regs_helper (x, NULL_RTX);
5564 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
5567 extract_mentioned_regs_helper (rtx x, rtx accum)
5573 /* Repeat is used to turn tail-recursion into iteration. */
5579 code = GET_CODE (x);
5583 return alloc_EXPR_LIST (0, x, accum);
5595 /* We do not run this function with arguments having side effects. */
5615 i = GET_RTX_LENGTH (code) - 1;
5616 fmt = GET_RTX_FORMAT (code);
5622 rtx tem = XEXP (x, i);
5624 /* If we are about to do the last recursive call
5625 needed at this level, change it into iteration. */
5632 accum = extract_mentioned_regs_helper (tem, accum);
5634 else if (fmt[i] == 'E')
5638 for (j = 0; j < XVECLEN (x, i); j++)
5639 accum = extract_mentioned_regs_helper (XVECEXP (x, i, j), accum);
5646 /* Determine whether INSN is MEM store pattern that we will consider moving.
5647 REGS_SET_BEFORE is bitmap of registers set before (and including) the
5648 current insn, REGS_SET_AFTER is bitmap of registers set after (and
5649 including) the insn in this basic block. We must be passing through BB from
5650 head to end, as we are using this fact to speed things up.
5652 The results are stored this way:
5654 -- the first anticipatable expression is added into ANTIC_STORE_LIST
5655 -- if the processed expression is not anticipatable, NULL_RTX is added
5656 there instead, so that we can use it as indicator that no further
5657 expression of this type may be anticipatable
5658 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
5659 consequently, all of them but this head are dead and may be deleted.
5660 -- if the expression is not available, the insn due to that it fails to be
5661 available is stored in reaching_reg.
5663 The things are complicated a bit by fact that there already may be stores
5664 to the same MEM from other blocks; also caller must take care of the
5665 necessary cleanup of the temporary markers after end of the basic block.
5669 find_moveable_store (rtx insn, int *regs_set_before, int *regs_set_after)
5671 struct ls_expr * ptr;
5673 int check_anticipatable, check_available;
5674 basic_block bb = BLOCK_FOR_INSN (insn);
5676 set = single_set (insn);
5680 dest = SET_DEST (set);
5682 if (! MEM_P (dest) || MEM_VOLATILE_P (dest)
5683 || GET_MODE (dest) == BLKmode)
5686 if (side_effects_p (dest))
5689 /* If we are handling exceptions, we must be careful with memory references
5690 that may trap. If we are not, the behavior is undefined, so we may just
5692 if (flag_non_call_exceptions && may_trap_p (dest))
5695 /* Even if the destination cannot trap, the source may. In this case we'd
5696 need to handle updating the REG_EH_REGION note. */
5697 if (find_reg_note (insn, REG_EH_REGION, NULL_RTX))
5700 /* Make sure that the SET_SRC of this store insns can be assigned to
5701 a register, or we will fail later on in replace_store_insn, which
5702 assumes that we can do this. But sometimes the target machine has
5703 oddities like MEM read-modify-write instruction. See for example
5705 if (!can_assign_to_reg_p (SET_SRC (set)))
5708 ptr = ldst_entry (dest);
5709 if (!ptr->pattern_regs)
5710 ptr->pattern_regs = extract_mentioned_regs (dest);
5712 /* Do not check for anticipatability if we either found one anticipatable
5713 store already, or tested for one and found out that it was killed. */
5714 check_anticipatable = 0;
5715 if (!ANTIC_STORE_LIST (ptr))
5716 check_anticipatable = 1;
5719 tmp = XEXP (ANTIC_STORE_LIST (ptr), 0);
5721 && BLOCK_FOR_INSN (tmp) != bb)
5722 check_anticipatable = 1;
5724 if (check_anticipatable)
5726 if (store_killed_before (dest, ptr->pattern_regs, insn, bb, regs_set_before))
5730 ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (tmp,
5731 ANTIC_STORE_LIST (ptr));
5734 /* It is not necessary to check whether store is available if we did
5735 it successfully before; if we failed before, do not bother to check
5736 until we reach the insn that caused us to fail. */
5737 check_available = 0;
5738 if (!AVAIL_STORE_LIST (ptr))
5739 check_available = 1;
5742 tmp = XEXP (AVAIL_STORE_LIST (ptr), 0);
5743 if (BLOCK_FOR_INSN (tmp) != bb)
5744 check_available = 1;
5746 if (check_available)
5748 /* Check that we have already reached the insn at that the check
5749 failed last time. */
5750 if (LAST_AVAIL_CHECK_FAILURE (ptr))
5752 for (tmp = BB_END (bb);
5753 tmp != insn && tmp != LAST_AVAIL_CHECK_FAILURE (ptr);
5754 tmp = PREV_INSN (tmp))
5757 check_available = 0;
5760 check_available = store_killed_after (dest, ptr->pattern_regs, insn,
5762 &LAST_AVAIL_CHECK_FAILURE (ptr));
5764 if (!check_available)
5765 AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn, AVAIL_STORE_LIST (ptr));
5768 /* Find available and anticipatable stores. */
5771 compute_store_table (void)
5777 int *last_set_in, *already_set;
5778 struct ls_expr * ptr, **prev_next_ptr_ptr;
5780 max_gcse_regno = max_reg_num ();
5782 reg_set_in_block = sbitmap_vector_alloc (last_basic_block,
5784 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
5786 pre_ldst_table = htab_create (13, pre_ldst_expr_hash,
5787 pre_ldst_expr_eq, NULL);
5788 last_set_in = XCNEWVEC (int, max_gcse_regno);
5789 already_set = XNEWVEC (int, max_gcse_regno);
5791 /* Find all the stores we care about. */
5794 /* First compute the registers set in this block. */
5795 regvec = last_set_in;
5797 FOR_BB_INSNS (bb, insn)
5799 if (! INSN_P (insn))
5804 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
5805 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
5807 last_set_in[regno] = INSN_UID (insn);
5808 SET_BIT (reg_set_in_block[bb->index], regno);
5812 pat = PATTERN (insn);
5813 compute_store_table_current_insn = insn;
5814 note_stores (pat, reg_set_info, reg_set_in_block[bb->index]);
5817 /* Now find the stores. */
5818 memset (already_set, 0, sizeof (int) * max_gcse_regno);
5819 regvec = already_set;
5820 FOR_BB_INSNS (bb, insn)
5822 if (! INSN_P (insn))
5827 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
5828 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
5829 already_set[regno] = 1;
5832 pat = PATTERN (insn);
5833 note_stores (pat, reg_set_info, NULL);
5835 /* Now that we've marked regs, look for stores. */
5836 find_moveable_store (insn, already_set, last_set_in);
5838 /* Unmark regs that are no longer set. */
5839 compute_store_table_current_insn = insn;
5840 note_stores (pat, reg_clear_last_set, last_set_in);
5843 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
5844 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno)
5845 && last_set_in[regno] == INSN_UID (insn))
5846 last_set_in[regno] = 0;
5850 #ifdef ENABLE_CHECKING
5851 /* last_set_in should now be all-zero. */
5852 for (regno = 0; regno < max_gcse_regno; regno++)
5853 gcc_assert (!last_set_in[regno]);
5856 /* Clear temporary marks. */
5857 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
5859 LAST_AVAIL_CHECK_FAILURE(ptr) = NULL_RTX;
5860 if (ANTIC_STORE_LIST (ptr)
5861 && (tmp = XEXP (ANTIC_STORE_LIST (ptr), 0)) == NULL_RTX)
5862 ANTIC_STORE_LIST (ptr) = XEXP (ANTIC_STORE_LIST (ptr), 1);
5866 /* Remove the stores that are not available anywhere, as there will
5867 be no opportunity to optimize them. */
5868 for (ptr = pre_ldst_mems, prev_next_ptr_ptr = &pre_ldst_mems;
5870 ptr = *prev_next_ptr_ptr)
5872 if (!AVAIL_STORE_LIST (ptr))
5874 *prev_next_ptr_ptr = ptr->next;
5875 htab_remove_elt_with_hash (pre_ldst_table, ptr, ptr->hash_index);
5876 free_ldst_entry (ptr);
5879 prev_next_ptr_ptr = &ptr->next;
5882 ret = enumerate_ldsts ();
5886 fprintf (dump_file, "ST_avail and ST_antic (shown under loads..)\n");
5887 print_ldst_list (dump_file);
5895 /* Check to see if the load X is aliased with STORE_PATTERN.
5896 AFTER is true if we are checking the case when STORE_PATTERN occurs
5900 load_kills_store (const_rtx x, const_rtx store_pattern, int after)
5903 return anti_dependence (x, store_pattern);
5905 return true_dependence (store_pattern, GET_MODE (store_pattern), x,
5909 /* Go through the entire insn X, looking for any loads which might alias
5910 STORE_PATTERN. Return true if found.
5911 AFTER is true if we are checking the case when STORE_PATTERN occurs
5912 after the insn X. */
5915 find_loads (const_rtx x, const_rtx store_pattern, int after)
5924 if (GET_CODE (x) == SET)
5929 if (load_kills_store (x, store_pattern, after))
5933 /* Recursively process the insn. */
5934 fmt = GET_RTX_FORMAT (GET_CODE (x));
5936 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
5939 ret |= find_loads (XEXP (x, i), store_pattern, after);
5940 else if (fmt[i] == 'E')
5941 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5942 ret |= find_loads (XVECEXP (x, i, j), store_pattern, after);
5948 store_killed_in_pat (const_rtx x, const_rtx pat, int after)
5950 if (GET_CODE (pat) == SET)
5952 rtx dest = SET_DEST (pat);
5954 if (GET_CODE (dest) == ZERO_EXTRACT)
5955 dest = XEXP (dest, 0);
5957 /* Check for memory stores to aliased objects. */
5959 && !expr_equiv_p (dest, x))
5963 if (output_dependence (dest, x))
5968 if (output_dependence (x, dest))
5974 if (find_loads (pat, x, after))
5980 /* Check if INSN kills the store pattern X (is aliased with it).
5981 AFTER is true if we are checking the case when store X occurs
5982 after the insn. Return true if it does. */
5985 store_killed_in_insn (const_rtx x, const_rtx x_regs, const_rtx insn, int after)
5987 const_rtx reg, base, note, pat;
5994 /* A normal or pure call might read from pattern,
5995 but a const call will not. */
5996 if (! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn))
5999 /* But even a const call reads its parameters. Check whether the
6000 base of some of registers used in mem is stack pointer. */
6001 for (reg = x_regs; reg; reg = XEXP (reg, 1))
6003 base = find_base_term (XEXP (reg, 0));
6005 || (GET_CODE (base) == ADDRESS
6006 && GET_MODE (base) == Pmode
6007 && XEXP (base, 0) == stack_pointer_rtx))
6014 pat = PATTERN (insn);
6015 if (GET_CODE (pat) == SET)
6017 if (store_killed_in_pat (x, pat, after))
6020 else if (GET_CODE (pat) == PARALLEL)
6024 for (i = 0; i < XVECLEN (pat, 0); i++)
6025 if (store_killed_in_pat (x, XVECEXP (pat, 0, i), after))
6028 else if (find_loads (PATTERN (insn), x, after))
6031 /* If this insn has a REG_EQUAL or REG_EQUIV note referencing a memory
6032 location aliased with X, then this insn kills X. */
6033 note = find_reg_equal_equiv_note (insn);
6036 note = XEXP (note, 0);
6038 /* However, if the note represents a must alias rather than a may
6039 alias relationship, then it does not kill X. */
6040 if (expr_equiv_p (note, x))
6043 /* See if there are any aliased loads in the note. */
6044 return find_loads (note, x, after);
6047 /* Returns true if the expression X is loaded or clobbered on or after INSN
6048 within basic block BB. REGS_SET_AFTER is bitmap of registers set in
6049 or after the insn. X_REGS is list of registers mentioned in X. If the store
6050 is killed, return the last insn in that it occurs in FAIL_INSN. */
6053 store_killed_after (const_rtx x, const_rtx x_regs, const_rtx insn, const_basic_block bb,
6054 int *regs_set_after, rtx *fail_insn)
6056 rtx last = BB_END (bb), act;
6058 if (!store_ops_ok (x_regs, regs_set_after))
6060 /* We do not know where it will happen. */
6062 *fail_insn = NULL_RTX;
6066 /* Scan from the end, so that fail_insn is determined correctly. */
6067 for (act = last; act != PREV_INSN (insn); act = PREV_INSN (act))
6068 if (store_killed_in_insn (x, x_regs, act, false))
6078 /* Returns true if the expression X is loaded or clobbered on or before INSN
6079 within basic block BB. X_REGS is list of registers mentioned in X.
6080 REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
6082 store_killed_before (const_rtx x, const_rtx x_regs, const_rtx insn, const_basic_block bb,
6083 int *regs_set_before)
6085 rtx first = BB_HEAD (bb);
6087 if (!store_ops_ok (x_regs, regs_set_before))
6090 for ( ; insn != PREV_INSN (first); insn = PREV_INSN (insn))
6091 if (store_killed_in_insn (x, x_regs, insn, true))
6097 /* Fill in available, anticipatable, transparent and kill vectors in
6098 STORE_DATA, based on lists of available and anticipatable stores. */
6100 build_store_vectors (void)
6103 int *regs_set_in_block;
6105 struct ls_expr * ptr;
6108 /* Build the gen_vector. This is any store in the table which is not killed
6109 by aliasing later in its block. */
6110 ae_gen = sbitmap_vector_alloc (last_basic_block, num_stores);
6111 sbitmap_vector_zero (ae_gen, last_basic_block);
6113 st_antloc = sbitmap_vector_alloc (last_basic_block, num_stores);
6114 sbitmap_vector_zero (st_antloc, last_basic_block);
6116 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6118 for (st = AVAIL_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
6120 insn = XEXP (st, 0);
6121 bb = BLOCK_FOR_INSN (insn);
6123 /* If we've already seen an available expression in this block,
6124 we can delete this one (It occurs earlier in the block). We'll
6125 copy the SRC expression to an unused register in case there
6126 are any side effects. */
6127 if (TEST_BIT (ae_gen[bb->index], ptr->index))
6129 rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
6131 fprintf (dump_file, "Removing redundant store:\n");
6132 replace_store_insn (r, XEXP (st, 0), bb, ptr);
6135 SET_BIT (ae_gen[bb->index], ptr->index);
6138 for (st = ANTIC_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
6140 insn = XEXP (st, 0);
6141 bb = BLOCK_FOR_INSN (insn);
6142 SET_BIT (st_antloc[bb->index], ptr->index);
6146 ae_kill = sbitmap_vector_alloc (last_basic_block, num_stores);
6147 sbitmap_vector_zero (ae_kill, last_basic_block);
6149 transp = sbitmap_vector_alloc (last_basic_block, num_stores);
6150 sbitmap_vector_zero (transp, last_basic_block);
6151 regs_set_in_block = XNEWVEC (int, max_gcse_regno);
6155 for (regno = 0; regno < max_gcse_regno; regno++)
6156 regs_set_in_block[regno] = TEST_BIT (reg_set_in_block[bb->index], regno);
6158 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6160 if (store_killed_after (ptr->pattern, ptr->pattern_regs, BB_HEAD (bb),
6161 bb, regs_set_in_block, NULL))
6163 /* It should not be necessary to consider the expression
6164 killed if it is both anticipatable and available. */
6165 if (!TEST_BIT (st_antloc[bb->index], ptr->index)
6166 || !TEST_BIT (ae_gen[bb->index], ptr->index))
6167 SET_BIT (ae_kill[bb->index], ptr->index);
6170 SET_BIT (transp[bb->index], ptr->index);
6174 free (regs_set_in_block);
6178 dump_sbitmap_vector (dump_file, "st_antloc", "", st_antloc, last_basic_block);
6179 dump_sbitmap_vector (dump_file, "st_kill", "", ae_kill, last_basic_block);
6180 dump_sbitmap_vector (dump_file, "Transpt", "", transp, last_basic_block);
6181 dump_sbitmap_vector (dump_file, "st_avloc", "", ae_gen, last_basic_block);
6185 /* Insert an instruction at the beginning of a basic block, and update
6186 the BB_HEAD if needed. */
6189 insert_insn_start_basic_block (rtx insn, basic_block bb)
6191 /* Insert at start of successor block. */
6192 rtx prev = PREV_INSN (BB_HEAD (bb));
6193 rtx before = BB_HEAD (bb);
6196 if (! LABEL_P (before)
6197 && !NOTE_INSN_BASIC_BLOCK_P (before))
6200 if (prev == BB_END (bb))
6202 before = NEXT_INSN (before);
6205 insn = emit_insn_after_noloc (insn, prev, bb);
6209 fprintf (dump_file, "STORE_MOTION insert store at start of BB %d:\n",
6211 print_inline_rtx (dump_file, insn, 6);
6212 fprintf (dump_file, "\n");
6216 /* This routine will insert a store on an edge. EXPR is the ldst entry for
6217 the memory reference, and E is the edge to insert it on. Returns nonzero
6218 if an edge insertion was performed. */
6221 insert_store (struct ls_expr * expr, edge e)
6228 /* We did all the deleted before this insert, so if we didn't delete a
6229 store, then we haven't set the reaching reg yet either. */
6230 if (expr->reaching_reg == NULL_RTX)
6233 if (e->flags & EDGE_FAKE)
6236 reg = expr->reaching_reg;
6237 insn = gen_move_insn (copy_rtx (expr->pattern), reg);
6239 /* If we are inserting this expression on ALL predecessor edges of a BB,
6240 insert it at the start of the BB, and reset the insert bits on the other
6241 edges so we don't try to insert it on the other edges. */
6243 FOR_EACH_EDGE (tmp, ei, e->dest->preds)
6244 if (!(tmp->flags & EDGE_FAKE))
6246 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
6248 gcc_assert (index != EDGE_INDEX_NO_EDGE);
6249 if (! TEST_BIT (pre_insert_map[index], expr->index))
6253 /* If tmp is NULL, we found an insertion on every edge, blank the
6254 insertion vector for these edges, and insert at the start of the BB. */
6255 if (!tmp && bb != EXIT_BLOCK_PTR)
6257 FOR_EACH_EDGE (tmp, ei, e->dest->preds)
6259 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
6260 RESET_BIT (pre_insert_map[index], expr->index);
6262 insert_insn_start_basic_block (insn, bb);
6266 /* We can't put stores in the front of blocks pointed to by abnormal
6267 edges since that may put a store where one didn't used to be. */
6268 gcc_assert (!(e->flags & EDGE_ABNORMAL));
6270 insert_insn_on_edge (insn, e);
6274 fprintf (dump_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
6275 e->src->index, e->dest->index);
6276 print_inline_rtx (dump_file, insn, 6);
6277 fprintf (dump_file, "\n");
6283 /* Remove any REG_EQUAL or REG_EQUIV notes containing a reference to the
6284 memory location in SMEXPR set in basic block BB.
6286 This could be rather expensive. */
6289 remove_reachable_equiv_notes (basic_block bb, struct ls_expr *smexpr)
6291 edge_iterator *stack, ei;
6294 sbitmap visited = sbitmap_alloc (last_basic_block);
6295 rtx last, insn, note;
6296 rtx mem = smexpr->pattern;
6298 stack = XNEWVEC (edge_iterator, n_basic_blocks);
6300 ei = ei_start (bb->succs);
6302 sbitmap_zero (visited);
6304 act = (EDGE_COUNT (ei_container (ei)) > 0 ? EDGE_I (ei_container (ei), 0) : NULL);
6312 sbitmap_free (visited);
6315 act = ei_edge (stack[--sp]);
6319 if (bb == EXIT_BLOCK_PTR
6320 || TEST_BIT (visited, bb->index))
6324 act = (! ei_end_p (ei)) ? ei_edge (ei) : NULL;
6327 SET_BIT (visited, bb->index);
6329 if (TEST_BIT (st_antloc[bb->index], smexpr->index))
6331 for (last = ANTIC_STORE_LIST (smexpr);
6332 BLOCK_FOR_INSN (XEXP (last, 0)) != bb;
6333 last = XEXP (last, 1))
6335 last = XEXP (last, 0);
6338 last = NEXT_INSN (BB_END (bb));
6340 for (insn = BB_HEAD (bb); insn != last; insn = NEXT_INSN (insn))
6343 note = find_reg_equal_equiv_note (insn);
6344 if (!note || !expr_equiv_p (XEXP (note, 0), mem))
6348 fprintf (dump_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6350 remove_note (insn, note);
6355 act = (! ei_end_p (ei)) ? ei_edge (ei) : NULL;
6357 if (EDGE_COUNT (bb->succs) > 0)
6361 ei = ei_start (bb->succs);
6362 act = (EDGE_COUNT (ei_container (ei)) > 0 ? EDGE_I (ei_container (ei), 0) : NULL);
6367 /* This routine will replace a store with a SET to a specified register. */
6370 replace_store_insn (rtx reg, rtx del, basic_block bb, struct ls_expr *smexpr)
6372 rtx insn, mem, note, set, ptr, pair;
6374 mem = smexpr->pattern;
6375 insn = gen_move_insn (reg, SET_SRC (single_set (del)));
6377 for (ptr = ANTIC_STORE_LIST (smexpr); ptr; ptr = XEXP (ptr, 1))
6378 if (XEXP (ptr, 0) == del)
6380 XEXP (ptr, 0) = insn;
6384 /* Move the notes from the deleted insn to its replacement, and patch
6385 up the LIBCALL notes. */
6386 REG_NOTES (insn) = REG_NOTES (del);
6388 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
6391 pair = XEXP (note, 0);
6392 note = find_reg_note (pair, REG_LIBCALL, NULL_RTX);
6393 XEXP (note, 0) = insn;
6395 note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
6398 pair = XEXP (note, 0);
6399 note = find_reg_note (pair, REG_RETVAL, NULL_RTX);
6400 XEXP (note, 0) = insn;
6403 /* Emit the insn AFTER all the notes are transferred.
6404 This is cheaper since we avoid df rescanning for the note change. */
6405 insn = emit_insn_after (insn, del);
6410 "STORE_MOTION delete insn in BB %d:\n ", bb->index);
6411 print_inline_rtx (dump_file, del, 6);
6412 fprintf (dump_file, "\nSTORE MOTION replaced with insn:\n ");
6413 print_inline_rtx (dump_file, insn, 6);
6414 fprintf (dump_file, "\n");
6419 /* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
6420 they are no longer accurate provided that they are reached by this
6421 definition, so drop them. */
6422 for (; insn != NEXT_INSN (BB_END (bb)); insn = NEXT_INSN (insn))
6425 set = single_set (insn);
6428 if (expr_equiv_p (SET_DEST (set), mem))
6430 note = find_reg_equal_equiv_note (insn);
6431 if (!note || !expr_equiv_p (XEXP (note, 0), mem))
6435 fprintf (dump_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6437 remove_note (insn, note);
6439 remove_reachable_equiv_notes (bb, smexpr);
6443 /* Delete a store, but copy the value that would have been stored into
6444 the reaching_reg for later storing. */
6447 delete_store (struct ls_expr * expr, basic_block bb)
6451 if (expr->reaching_reg == NULL_RTX)
6452 expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
6454 reg = expr->reaching_reg;
6456 for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
6459 if (BLOCK_FOR_INSN (del) == bb)
6461 /* We know there is only one since we deleted redundant
6462 ones during the available computation. */
6463 replace_store_insn (reg, del, bb, expr);
6469 /* Free memory used by store motion. */
6472 free_store_memory (void)
6477 sbitmap_vector_free (ae_gen);
6479 sbitmap_vector_free (ae_kill);
6481 sbitmap_vector_free (transp);
6483 sbitmap_vector_free (st_antloc);
6485 sbitmap_vector_free (pre_insert_map);
6487 sbitmap_vector_free (pre_delete_map);
6488 if (reg_set_in_block)
6489 sbitmap_vector_free (reg_set_in_block);
6491 ae_gen = ae_kill = transp = st_antloc = NULL;
6492 pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
6495 /* Perform store motion. Much like gcse, except we move expressions the
6496 other way by looking at the flowgraph in reverse. */
6503 struct ls_expr * ptr;
6504 int update_flow = 0;
6508 fprintf (dump_file, "before store motion\n");
6509 print_rtl (dump_file, get_insns ());
6512 init_alias_analysis ();
6514 /* Find all the available and anticipatable stores. */
6515 num_stores = compute_store_table ();
6516 if (num_stores == 0)
6518 htab_delete (pre_ldst_table);
6519 pre_ldst_table = NULL;
6520 sbitmap_vector_free (reg_set_in_block);
6521 end_alias_analysis ();
6525 /* Now compute kill & transp vectors. */
6526 build_store_vectors ();
6527 add_noreturn_fake_exit_edges ();
6528 connect_infinite_loops_to_exit ();
6530 edge_list = pre_edge_rev_lcm (num_stores, transp, ae_gen,
6531 st_antloc, ae_kill, &pre_insert_map,
6534 /* Now we want to insert the new stores which are going to be needed. */
6535 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6537 /* If any of the edges we have above are abnormal, we can't move this
6539 for (x = NUM_EDGES (edge_list) - 1; x >= 0; x--)
6540 if (TEST_BIT (pre_insert_map[x], ptr->index)
6541 && (INDEX_EDGE (edge_list, x)->flags & EDGE_ABNORMAL))
6546 if (dump_file != NULL)
6548 "Can't replace store %d: abnormal edge from %d to %d\n",
6549 ptr->index, INDEX_EDGE (edge_list, x)->src->index,
6550 INDEX_EDGE (edge_list, x)->dest->index);
6554 /* Now we want to insert the new stores which are going to be needed. */
6557 if (TEST_BIT (pre_delete_map[bb->index], ptr->index))
6558 delete_store (ptr, bb);
6560 for (x = 0; x < NUM_EDGES (edge_list); x++)
6561 if (TEST_BIT (pre_insert_map[x], ptr->index))
6562 update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
6566 commit_edge_insertions ();
6568 free_store_memory ();
6569 free_edge_list (edge_list);
6570 remove_fake_exit_edges ();
6571 end_alias_analysis ();
6575 /* Entry point for jump bypassing optimization pass. */
6582 /* We do not construct an accurate cfg in functions which call
6583 setjmp, so just punt to be safe. */
6584 if (current_function_calls_setjmp)
6587 /* Identify the basic block information for this function, including
6588 successors and predecessors. */
6589 max_gcse_regno = max_reg_num ();
6592 dump_flow_info (dump_file, dump_flags);
6594 /* Return if there's nothing to do, or it is too expensive. */
6595 if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1
6596 || is_too_expensive (_ ("jump bypassing disabled")))
6599 gcc_obstack_init (&gcse_obstack);
6602 /* We need alias. */
6603 init_alias_analysis ();
6605 /* Record where pseudo-registers are set. This data is kept accurate
6606 during each pass. ??? We could also record hard-reg information here
6607 [since it's unchanging], however it is currently done during hash table
6610 It may be tempting to compute MEM set information here too, but MEM sets
6611 will be subject to code motion one day and thus we need to compute
6612 information about memory sets when we build the hash tables. */
6614 alloc_reg_set_mem (max_gcse_regno);
6617 max_gcse_regno = max_reg_num ();
6619 changed = one_cprop_pass (MAX_GCSE_PASSES + 2, true, true);
6624 fprintf (dump_file, "BYPASS of %s: %d basic blocks, ",
6625 current_function_name (), n_basic_blocks);
6626 fprintf (dump_file, "%d bytes\n\n", bytes_used);
6629 obstack_free (&gcse_obstack, NULL);
6630 free_reg_set_mem ();
6632 /* We are finished with alias. */
6633 end_alias_analysis ();
6638 /* Return true if the graph is too expensive to optimize. PASS is the
6639 optimization about to be performed. */
6642 is_too_expensive (const char *pass)
6644 /* Trying to perform global optimizations on flow graphs which have
6645 a high connectivity will take a long time and is unlikely to be
6646 particularly useful.
6648 In normal circumstances a cfg should have about twice as many
6649 edges as blocks. But we do not want to punish small functions
6650 which have a couple switch statements. Rather than simply
6651 threshold the number of blocks, uses something with a more
6652 graceful degradation. */
6653 if (n_edges > 20000 + n_basic_blocks * 4)
6655 warning (OPT_Wdisabled_optimization,
6656 "%s: %d basic blocks and %d edges/basic block",
6657 pass, n_basic_blocks, n_edges / n_basic_blocks);
6662 /* If allocating memory for the cprop bitmap would take up too much
6663 storage it's better just to disable the optimization. */
6665 * SBITMAP_SET_SIZE (max_reg_num ())
6666 * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
6668 warning (OPT_Wdisabled_optimization,
6669 "%s: %d basic blocks and %d registers",
6670 pass, n_basic_blocks, max_reg_num ());
6679 gate_handle_jump_bypass (void)
6681 return optimize > 0 && flag_gcse;
6684 /* Perform jump bypassing and control flow optimizations. */
6686 rest_of_handle_jump_bypass (void)
6688 delete_unreachable_blocks ();
6689 if (bypass_jumps ())
6691 delete_trivially_dead_insns (get_insns (), max_reg_num ());
6692 rebuild_jump_labels (get_insns ());
6698 struct tree_opt_pass pass_jump_bypass =
6700 "bypass", /* name */
6701 gate_handle_jump_bypass, /* gate */
6702 rest_of_handle_jump_bypass, /* execute */
6705 0, /* static_pass_number */
6706 TV_BYPASS, /* tv_id */
6707 0, /* properties_required */
6708 0, /* properties_provided */
6709 0, /* properties_destroyed */
6710 0, /* todo_flags_start */
6712 TODO_ggc_collect | TODO_verify_flow, /* todo_flags_finish */
6718 gate_handle_gcse (void)
6720 return optimize > 0 && flag_gcse;
6725 rest_of_handle_gcse (void)
6727 int save_csb, save_cfj;
6729 tem = gcse_main (get_insns ());
6730 delete_trivially_dead_insns (get_insns (), max_reg_num ());
6731 rebuild_jump_labels (get_insns ());
6732 save_csb = flag_cse_skip_blocks;
6733 save_cfj = flag_cse_follow_jumps;
6734 flag_cse_skip_blocks = flag_cse_follow_jumps = 0;
6736 /* If -fexpensive-optimizations, re-run CSE to clean up things done
6738 if (flag_expensive_optimizations)
6740 timevar_push (TV_CSE);
6741 tem2 = cse_main (get_insns (), max_reg_num ());
6742 df_finish_pass (false);
6743 purge_all_dead_edges ();
6744 delete_trivially_dead_insns (get_insns (), max_reg_num ());
6745 timevar_pop (TV_CSE);
6746 cse_not_expected = !flag_rerun_cse_after_loop;
6749 /* If gcse or cse altered any jumps, rerun jump optimizations to clean
6753 timevar_push (TV_JUMP);
6754 rebuild_jump_labels (get_insns ());
6756 timevar_pop (TV_JUMP);
6759 flag_cse_skip_blocks = save_csb;
6760 flag_cse_follow_jumps = save_cfj;
6764 struct tree_opt_pass pass_gcse =
6767 gate_handle_gcse, /* gate */
6768 rest_of_handle_gcse, /* execute */
6771 0, /* static_pass_number */
6772 TV_GCSE, /* tv_id */
6773 0, /* properties_required */
6774 0, /* properties_provided */
6775 0, /* properties_destroyed */
6776 0, /* todo_flags_start */
6777 TODO_df_finish | TODO_verify_rtl_sharing |
6779 TODO_verify_flow | TODO_ggc_collect, /* todo_flags_finish */
6784 #include "gt-gcse.h"