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 /* Maximum register number in function prior to doing gcse + 1.
384 Registers created during this pass have regno >= max_gcse_regno.
385 This is named with "gcse" to not collide with global of same name. */
386 static unsigned int max_gcse_regno
;
388 /* Table of registers that are modified.
390 For each register, each element is a list of places where the pseudo-reg
393 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
394 requires knowledge of which blocks kill which regs [and thus could use
395 a bitmap instead of the lists `reg_set_table' uses].
397 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
398 num-regs) [however perhaps it may be useful to keep the data as is]. One
399 advantage of recording things this way is that `reg_set_table' is fairly
400 sparse with respect to pseudo regs but for hard regs could be fairly dense
401 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
402 up functions like compute_transp since in the case of pseudo-regs we only
403 need to iterate over the number of times a pseudo-reg is set, not over the
404 number of basic blocks [clearly there is a bit of a slow down in the cases
405 where a pseudo is set more than once in a block, however it is believed
406 that the net effect is to speed things up]. This isn't done for hard-regs
407 because recording call-clobbered hard-regs in `reg_set_table' at each
408 function call can consume a fair bit of memory, and iterating over
409 hard-regs stored this way in compute_transp will be more expensive. */
411 typedef struct reg_set
413 /* The next setting of this register. */
414 struct reg_set
*next
;
415 /* The index of the block where it was set. */
419 static reg_set
**reg_set_table
;
421 /* Size of `reg_set_table'.
422 The table starts out at max_gcse_regno + slop, and is enlarged as
424 static int reg_set_table_size
;
426 /* Amount to grow `reg_set_table' by when it's full. */
427 #define REG_SET_TABLE_SLOP 100
429 /* This is a list of expressions which are MEMs and will be used by load
431 Load motion tracks MEMs which aren't killed by
432 anything except itself. (i.e., loads and stores to a single location).
433 We can then allow movement of these MEM refs with a little special
434 allowance. (all stores copy the same value to the reaching reg used
435 for the loads). This means all values used to store into memory must have
436 no side effects so we can re-issue the setter value.
437 Store Motion uses this structure as an expression table to track stores
438 which look interesting, and might be moveable towards the exit block. */
442 struct expr
* expr
; /* Gcse expression reference for LM. */
443 rtx pattern
; /* Pattern of this mem. */
444 rtx pattern_regs
; /* List of registers mentioned by the mem. */
445 rtx loads
; /* INSN list of loads seen. */
446 rtx stores
; /* INSN list of stores seen. */
447 struct ls_expr
* next
; /* Next in the list. */
448 int invalid
; /* Invalid for some reason. */
449 int index
; /* If it maps to a bitmap index. */
450 unsigned int hash_index
; /* Index when in a hash table. */
451 rtx reaching_reg
; /* Register to use when re-writing. */
454 /* Array of implicit set patterns indexed by basic block index. */
455 static rtx
*implicit_sets
;
457 /* Head of the list of load/store memory refs. */
458 static struct ls_expr
* pre_ldst_mems
= NULL
;
460 /* Hashtable for the load/store memory refs. */
461 static htab_t pre_ldst_table
= NULL
;
463 /* Bitmap containing one bit for each register in the program.
464 Used when performing GCSE to track which registers have been set since
465 the start of the basic block. */
466 static regset reg_set_bitmap
;
468 /* For each block, a bitmap of registers set in the block.
469 This is used by compute_transp.
470 It is computed during hash table computation and not by compute_sets
471 as it includes registers added since the last pass (or between cprop and
472 gcse) and it's currently not easy to realloc sbitmap vectors. */
473 static sbitmap
*reg_set_in_block
;
475 /* Array, indexed by basic block number for a list of insns which modify
476 memory within that block. */
477 static rtx
* modify_mem_list
;
478 static bitmap modify_mem_list_set
;
480 /* This array parallels modify_mem_list, but is kept canonicalized. */
481 static rtx
* canon_modify_mem_list
;
483 /* Bitmap indexed by block numbers to record which blocks contain
485 static bitmap blocks_with_calls
;
487 /* Various variables for statistics gathering. */
489 /* Memory used in a pass.
490 This isn't intended to be absolutely precise. Its intent is only
491 to keep an eye on memory usage. */
492 static int bytes_used
;
494 /* GCSE substitutions made. */
495 static int gcse_subst_count
;
496 /* Number of copy instructions created. */
497 static int gcse_create_count
;
498 /* Number of local constants propagated. */
499 static int local_const_prop_count
;
500 /* Number of local copies propagated. */
501 static int local_copy_prop_count
;
502 /* Number of global constants propagated. */
503 static int global_const_prop_count
;
504 /* Number of global copies propagated. */
505 static int global_copy_prop_count
;
507 /* For available exprs */
508 static sbitmap
*ae_kill
, *ae_gen
;
510 static void compute_can_copy (void);
511 static void *gmalloc (size_t) ATTRIBUTE_MALLOC
;
512 static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC
;
513 static void *grealloc (void *, size_t);
514 static void *gcse_alloc (unsigned long);
515 static void alloc_gcse_mem (void);
516 static void free_gcse_mem (void);
517 static void alloc_reg_set_mem (int);
518 static void free_reg_set_mem (void);
519 static void record_one_set (int, rtx
);
520 static void record_set_info (rtx
, const_rtx
, void *);
521 static void compute_sets (void);
522 static void hash_scan_insn (rtx
, struct hash_table
*, int);
523 static void hash_scan_set (rtx
, rtx
, struct hash_table
*);
524 static void hash_scan_clobber (rtx
, rtx
, struct hash_table
*);
525 static void hash_scan_call (rtx
, rtx
, struct hash_table
*);
526 static int want_to_gcse_p (rtx
);
527 static bool can_assign_to_reg_p (rtx
);
528 static bool gcse_constant_p (const_rtx
);
529 static int oprs_unchanged_p (const_rtx
, const_rtx
, int);
530 static int oprs_anticipatable_p (const_rtx
, const_rtx
);
531 static int oprs_available_p (const_rtx
, const_rtx
);
532 static void insert_expr_in_table (rtx
, enum machine_mode
, rtx
, int, int,
533 struct hash_table
*);
534 static void insert_set_in_table (rtx
, rtx
, struct hash_table
*);
535 static unsigned int hash_expr (const_rtx
, enum machine_mode
, int *, int);
536 static unsigned int hash_set (int, int);
537 static int expr_equiv_p (const_rtx
, const_rtx
);
538 static void record_last_reg_set_info (rtx
, int);
539 static void record_last_mem_set_info (rtx
);
540 static void record_last_set_info (rtx
, const_rtx
, void *);
541 static void compute_hash_table (struct hash_table
*);
542 static void alloc_hash_table (int, struct hash_table
*, int);
543 static void free_hash_table (struct hash_table
*);
544 static void compute_hash_table_work (struct hash_table
*);
545 static void dump_hash_table (FILE *, const char *, struct hash_table
*);
546 static struct expr
*lookup_set (unsigned int, struct hash_table
*);
547 static struct expr
*next_set (unsigned int, struct expr
*);
548 static void reset_opr_set_tables (void);
549 static int oprs_not_set_p (const_rtx
, const_rtx
);
550 static void mark_call (rtx
);
551 static void mark_set (rtx
, rtx
);
552 static void mark_clobber (rtx
, rtx
);
553 static void mark_oprs_set (rtx
);
554 static void alloc_cprop_mem (int, int);
555 static void free_cprop_mem (void);
556 static void compute_transp (const_rtx
, int, sbitmap
*, int);
557 static void compute_transpout (void);
558 static void compute_local_properties (sbitmap
*, sbitmap
*, sbitmap
*,
559 struct hash_table
*);
560 static void compute_cprop_data (void);
561 static void find_used_regs (rtx
*, void *);
562 static int try_replace_reg (rtx
, rtx
, rtx
);
563 static struct expr
*find_avail_set (int, rtx
);
564 static int cprop_jump (basic_block
, rtx
, rtx
, rtx
, rtx
);
565 static void mems_conflict_for_gcse_p (rtx
, const_rtx
, void *);
566 static int load_killed_in_block_p (const_basic_block
, int, const_rtx
, int);
567 static void canon_list_insert (rtx
, const_rtx
, void *);
568 static int cprop_insn (rtx
, int);
569 static int cprop (int);
570 static void find_implicit_sets (void);
571 static int one_cprop_pass (int, bool, bool);
572 static bool constprop_register (rtx
, rtx
, rtx
, bool);
573 static struct expr
*find_bypass_set (int, int);
574 static bool reg_killed_on_edge (const_rtx
, const_edge
);
575 static int bypass_block (basic_block
, rtx
, rtx
);
576 static int bypass_conditional_jumps (void);
577 static void alloc_pre_mem (int, int);
578 static void free_pre_mem (void);
579 static void compute_pre_data (void);
580 static int pre_expr_reaches_here_p (basic_block
, struct expr
*,
582 static void insert_insn_end_basic_block (struct expr
*, basic_block
, int);
583 static void pre_insert_copy_insn (struct expr
*, rtx
);
584 static void pre_insert_copies (void);
585 static int pre_delete (void);
586 static int pre_gcse (void);
587 static int one_pre_gcse_pass (int);
588 static void add_label_notes (rtx
, rtx
);
589 static void alloc_code_hoist_mem (int, int);
590 static void free_code_hoist_mem (void);
591 static void compute_code_hoist_vbeinout (void);
592 static void compute_code_hoist_data (void);
593 static int hoist_expr_reaches_here_p (basic_block
, int, basic_block
, char *);
594 static void hoist_code (void);
595 static int one_code_hoisting_pass (void);
596 static rtx
process_insert_insn (struct expr
*);
597 static int pre_edge_insert (struct edge_list
*, struct expr
**);
598 static int pre_expr_reaches_here_p_work (basic_block
, struct expr
*,
599 basic_block
, char *);
600 static struct ls_expr
* ldst_entry (rtx
);
601 static void free_ldst_entry (struct ls_expr
*);
602 static void free_ldst_mems (void);
603 static void print_ldst_list (FILE *);
604 static struct ls_expr
* find_rtx_in_ldst (rtx
);
605 static int enumerate_ldsts (void);
606 static inline struct ls_expr
* first_ls_expr (void);
607 static inline struct ls_expr
* next_ls_expr (struct ls_expr
*);
608 static int simple_mem (const_rtx
);
609 static void invalidate_any_buried_refs (rtx
);
610 static void compute_ld_motion_mems (void);
611 static void trim_ld_motion_mems (void);
612 static void update_ld_motion_stores (struct expr
*);
613 static void reg_set_info (rtx
, const_rtx
, void *);
614 static void reg_clear_last_set (rtx
, const_rtx
, void *);
615 static bool store_ops_ok (const_rtx
, int *);
616 static rtx
extract_mentioned_regs (rtx
);
617 static rtx
extract_mentioned_regs_helper (rtx
, rtx
);
618 static void find_moveable_store (rtx
, int *, int *);
619 static int compute_store_table (void);
620 static bool load_kills_store (const_rtx
, const_rtx
, int);
621 static bool find_loads (const_rtx
, const_rtx
, int);
622 static bool store_killed_in_insn (const_rtx
, const_rtx
, const_rtx
, int);
623 static bool store_killed_after (const_rtx
, const_rtx
, const_rtx
, const_basic_block
, int *, rtx
*);
624 static bool store_killed_before (const_rtx
, const_rtx
, const_rtx
, const_basic_block
, int *);
625 static void build_store_vectors (void);
626 static void insert_insn_start_basic_block (rtx
, basic_block
);
627 static int insert_store (struct ls_expr
*, edge
);
628 static void remove_reachable_equiv_notes (basic_block
, struct ls_expr
*);
629 static void replace_store_insn (rtx
, rtx
, basic_block
, struct ls_expr
*);
630 static void delete_store (struct ls_expr
*, basic_block
);
631 static void free_store_memory (void);
632 static void store_motion (void);
633 static void free_insn_expr_list_list (rtx
*);
634 static void clear_modify_mem_tables (void);
635 static void free_modify_mem_tables (void);
636 static rtx
gcse_emit_move_after (rtx
, rtx
, rtx
);
637 static void local_cprop_find_used_regs (rtx
*, void *);
638 static bool do_local_cprop (rtx
, rtx
, bool, rtx
*);
639 static bool adjust_libcall_notes (rtx
, rtx
, rtx
, rtx
*);
640 static void local_cprop_pass (bool);
641 static bool is_too_expensive (const char *);
644 /* Entry point for global common subexpression elimination.
645 F is the first instruction in the function. Return nonzero if a
649 gcse_main (rtx f ATTRIBUTE_UNUSED
)
652 /* Bytes used at start of pass. */
653 int initial_bytes_used
;
654 /* Maximum number of bytes used by a pass. */
656 /* Point to release obstack data from for each pass. */
657 char *gcse_obstack_bottom
;
659 /* We do not construct an accurate cfg in functions which call
660 setjmp, so just punt to be safe. */
661 if (current_function_calls_setjmp
)
664 /* Assume that we do not need to run jump optimizations after gcse. */
665 run_jump_opt_after_gcse
= 0;
667 /* Identify the basic block information for this function, including
668 successors and predecessors. */
669 max_gcse_regno
= max_reg_num ();
671 df_note_add_problem ();
675 dump_flow_info (dump_file
, dump_flags
);
677 /* Return if there's nothing to do, or it is too expensive. */
678 if (n_basic_blocks
<= NUM_FIXED_BLOCKS
+ 1
679 || is_too_expensive (_("GCSE disabled")))
682 gcc_obstack_init (&gcse_obstack
);
686 init_alias_analysis ();
687 /* Record where pseudo-registers are set. This data is kept accurate
688 during each pass. ??? We could also record hard-reg information here
689 [since it's unchanging], however it is currently done during hash table
692 It may be tempting to compute MEM set information here too, but MEM sets
693 will be subject to code motion one day and thus we need to compute
694 information about memory sets when we build the hash tables. */
696 alloc_reg_set_mem (max_gcse_regno
);
700 initial_bytes_used
= bytes_used
;
702 gcse_obstack_bottom
= gcse_alloc (1);
704 while (changed
&& pass
< MAX_GCSE_PASSES
)
708 fprintf (dump_file
, "GCSE pass %d\n\n", pass
+ 1);
710 /* Initialize bytes_used to the space for the pred/succ lists,
711 and the reg_set_table data. */
712 bytes_used
= initial_bytes_used
;
714 /* Each pass may create new registers, so recalculate each time. */
715 max_gcse_regno
= max_reg_num ();
719 /* Don't allow constant propagation to modify jumps
721 timevar_push (TV_CPROP1
);
722 changed
= one_cprop_pass (pass
+ 1, false, false);
723 timevar_pop (TV_CPROP1
);
729 timevar_push (TV_PRE
);
730 changed
|= one_pre_gcse_pass (pass
+ 1);
731 /* We may have just created new basic blocks. Release and
732 recompute various things which are sized on the number of
736 free_modify_mem_tables ();
737 modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
738 canon_modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
741 alloc_reg_set_mem (max_reg_num ());
743 run_jump_opt_after_gcse
= 1;
744 timevar_pop (TV_PRE
);
747 if (max_pass_bytes
< bytes_used
)
748 max_pass_bytes
= bytes_used
;
750 /* Free up memory, then reallocate for code hoisting. We can
751 not re-use the existing allocated memory because the tables
752 will not have info for the insns or registers created by
753 partial redundancy elimination. */
756 /* It does not make sense to run code hoisting unless we are optimizing
757 for code size -- it rarely makes programs faster, and can make
758 them bigger if we did partial redundancy elimination (when optimizing
759 for space, we don't run the partial redundancy algorithms). */
762 timevar_push (TV_HOIST
);
763 max_gcse_regno
= max_reg_num ();
765 changed
|= one_code_hoisting_pass ();
768 if (max_pass_bytes
< bytes_used
)
769 max_pass_bytes
= bytes_used
;
770 timevar_pop (TV_HOIST
);
775 fprintf (dump_file
, "\n");
779 obstack_free (&gcse_obstack
, gcse_obstack_bottom
);
783 /* Do one last pass of copy propagation, including cprop into
784 conditional jumps. */
786 max_gcse_regno
= max_reg_num ();
788 /* This time, go ahead and allow cprop to alter jumps. */
789 timevar_push (TV_CPROP2
);
790 one_cprop_pass (pass
+ 1, true, true);
791 timevar_pop (TV_CPROP2
);
796 fprintf (dump_file
, "GCSE of %s: %d basic blocks, ",
797 current_function_name (), n_basic_blocks
);
798 fprintf (dump_file
, "%d pass%s, %d bytes\n\n",
799 pass
, pass
> 1 ? "es" : "", max_pass_bytes
);
802 obstack_free (&gcse_obstack
, NULL
);
805 /* We are finished with alias. */
806 end_alias_analysis ();
808 if (!optimize_size
&& flag_gcse_sm
)
810 timevar_push (TV_LSM
);
812 timevar_pop (TV_LSM
);
815 /* Record where pseudo-registers are set. */
816 return run_jump_opt_after_gcse
;
819 /* Misc. utilities. */
821 /* Nonzero for each mode that supports (set (reg) (reg)).
822 This is trivially true for integer and floating point values.
823 It may or may not be true for condition codes. */
824 static char can_copy
[(int) NUM_MACHINE_MODES
];
826 /* Compute which modes support reg/reg copy operations. */
829 compute_can_copy (void)
832 #ifndef AVOID_CCMODE_COPIES
835 memset (can_copy
, 0, NUM_MACHINE_MODES
);
838 for (i
= 0; i
< NUM_MACHINE_MODES
; i
++)
839 if (GET_MODE_CLASS (i
) == MODE_CC
)
841 #ifdef AVOID_CCMODE_COPIES
844 reg
= gen_rtx_REG ((enum machine_mode
) i
, LAST_VIRTUAL_REGISTER
+ 1);
845 insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, reg
));
846 if (recog (PATTERN (insn
), insn
, NULL
) >= 0)
856 /* Returns whether the mode supports reg/reg copy operations. */
859 can_copy_p (enum machine_mode mode
)
861 static bool can_copy_init_p
= false;
863 if (! can_copy_init_p
)
866 can_copy_init_p
= true;
869 return can_copy
[mode
] != 0;
872 /* Cover function to xmalloc to record bytes allocated. */
875 gmalloc (size_t size
)
878 return xmalloc (size
);
881 /* Cover function to xcalloc to record bytes allocated. */
884 gcalloc (size_t nelem
, size_t elsize
)
886 bytes_used
+= nelem
* elsize
;
887 return xcalloc (nelem
, elsize
);
890 /* Cover function to xrealloc.
891 We don't record the additional size since we don't know it.
892 It won't affect memory usage stats much anyway. */
895 grealloc (void *ptr
, size_t size
)
897 return xrealloc (ptr
, size
);
900 /* Cover function to obstack_alloc. */
903 gcse_alloc (unsigned long size
)
906 return obstack_alloc (&gcse_obstack
, size
);
909 /* Allocate memory for the cuid mapping array,
910 and reg/memory set tracking tables.
912 This is called at the start of each pass. */
915 alloc_gcse_mem (void)
921 /* Find the largest UID and create a mapping from UIDs to CUIDs.
922 CUIDs are like UIDs except they increase monotonically, have no gaps,
923 and only apply to real insns.
924 (Actually, there are gaps, for insn that are not inside a basic block.
925 but we should never see those anyway, so this is OK.) */
927 max_uid
= get_max_uid ();
928 uid_cuid
= gcalloc (max_uid
+ 1, sizeof (int));
931 FOR_BB_INSNS (bb
, insn
)
934 uid_cuid
[INSN_UID (insn
)] = i
++;
936 uid_cuid
[INSN_UID (insn
)] = i
;
941 /* Allocate vars to track sets of regs. */
942 reg_set_bitmap
= BITMAP_ALLOC (NULL
);
944 /* Allocate vars to track sets of regs, memory per block. */
945 reg_set_in_block
= sbitmap_vector_alloc (last_basic_block
, max_gcse_regno
);
946 /* Allocate array to keep a list of insns which modify memory in each
948 modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
949 canon_modify_mem_list
= gcalloc (last_basic_block
, sizeof (rtx
));
950 modify_mem_list_set
= BITMAP_ALLOC (NULL
);
951 blocks_with_calls
= BITMAP_ALLOC (NULL
);
954 /* Free memory allocated by alloc_gcse_mem. */
961 BITMAP_FREE (reg_set_bitmap
);
963 sbitmap_vector_free (reg_set_in_block
);
964 free_modify_mem_tables ();
965 BITMAP_FREE (modify_mem_list_set
);
966 BITMAP_FREE (blocks_with_calls
);
969 /* Compute the local properties of each recorded expression.
971 Local properties are those that are defined by the block, irrespective of
974 An expression is transparent in a block if its operands are not modified
977 An expression is computed (locally available) in a block if it is computed
978 at least once and expression would contain the same value if the
979 computation was moved to the end of the block.
981 An expression is locally anticipatable in a block if it is computed at
982 least once and expression would contain the same value if the computation
983 was moved to the beginning of the block.
985 We call this routine for cprop, pre and code hoisting. They all compute
986 basically the same information and thus can easily share this code.
988 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
989 properties. If NULL, then it is not necessary to compute or record that
992 TABLE controls which hash table to look at. If it is set hash table,
993 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
997 compute_local_properties (sbitmap
*transp
, sbitmap
*comp
, sbitmap
*antloc
,
998 struct hash_table
*table
)
1002 /* Initialize any bitmaps that were passed in. */
1006 sbitmap_vector_zero (transp
, last_basic_block
);
1008 sbitmap_vector_ones (transp
, last_basic_block
);
1012 sbitmap_vector_zero (comp
, last_basic_block
);
1014 sbitmap_vector_zero (antloc
, last_basic_block
);
1016 for (i
= 0; i
< table
->size
; i
++)
1020 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1022 int indx
= expr
->bitmap_index
;
1025 /* The expression is transparent in this block if it is not killed.
1026 We start by assuming all are transparent [none are killed], and
1027 then reset the bits for those that are. */
1029 compute_transp (expr
->expr
, indx
, transp
, table
->set_p
);
1031 /* The occurrences recorded in antic_occr are exactly those that
1032 we want to set to nonzero in ANTLOC. */
1034 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
1036 SET_BIT (antloc
[BLOCK_NUM (occr
->insn
)], indx
);
1038 /* While we're scanning the table, this is a good place to
1040 occr
->deleted_p
= 0;
1043 /* The occurrences recorded in avail_occr are exactly those that
1044 we want to set to nonzero in COMP. */
1046 for (occr
= expr
->avail_occr
; occr
!= NULL
; occr
= occr
->next
)
1048 SET_BIT (comp
[BLOCK_NUM (occr
->insn
)], indx
);
1050 /* While we're scanning the table, this is a good place to
1055 /* While we're scanning the table, this is a good place to
1057 expr
->reaching_reg
= 0;
1062 /* Register set information.
1064 `reg_set_table' records where each register is set or otherwise
1067 static struct obstack reg_set_obstack
;
1070 alloc_reg_set_mem (int n_regs
)
1072 reg_set_table_size
= n_regs
+ REG_SET_TABLE_SLOP
;
1073 reg_set_table
= gcalloc (reg_set_table_size
, sizeof (struct reg_set
*));
1075 gcc_obstack_init (®_set_obstack
);
1079 free_reg_set_mem (void)
1081 free (reg_set_table
);
1082 obstack_free (®_set_obstack
, NULL
);
1085 /* Record REGNO in the reg_set table. */
1088 record_one_set (int regno
, rtx insn
)
1090 /* Allocate a new reg_set element and link it onto the list. */
1091 struct reg_set
*new_reg_info
;
1093 /* If the table isn't big enough, enlarge it. */
1094 if (regno
>= reg_set_table_size
)
1096 int new_size
= regno
+ REG_SET_TABLE_SLOP
;
1098 reg_set_table
= grealloc (reg_set_table
,
1099 new_size
* sizeof (struct reg_set
*));
1100 memset (reg_set_table
+ reg_set_table_size
, 0,
1101 (new_size
- reg_set_table_size
) * sizeof (struct reg_set
*));
1102 reg_set_table_size
= new_size
;
1105 new_reg_info
= obstack_alloc (®_set_obstack
, sizeof (struct reg_set
));
1106 bytes_used
+= sizeof (struct reg_set
);
1107 new_reg_info
->bb_index
= BLOCK_NUM (insn
);
1108 new_reg_info
->next
= reg_set_table
[regno
];
1109 reg_set_table
[regno
] = new_reg_info
;
1112 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1113 an insn. The DATA is really the instruction in which the SET is
1117 record_set_info (rtx dest
, const_rtx setter ATTRIBUTE_UNUSED
, void *data
)
1119 rtx record_set_insn
= (rtx
) data
;
1121 if (REG_P (dest
) && REGNO (dest
) >= FIRST_PSEUDO_REGISTER
)
1122 record_one_set (REGNO (dest
), record_set_insn
);
1125 /* Scan the function and record each set of each pseudo-register.
1127 This is called once, at the start of the gcse pass. See the comments for
1128 `reg_set_table' for further documentation. */
1137 FOR_BB_INSNS (bb
, insn
)
1139 note_stores (PATTERN (insn
), record_set_info
, insn
);
1142 /* Hash table support. */
1144 struct reg_avail_info
1146 basic_block last_bb
;
1151 static struct reg_avail_info
*reg_avail_info
;
1152 static basic_block current_bb
;
1155 /* See whether X, the source of a set, is something we want to consider for
1159 want_to_gcse_p (rtx x
)
1162 /* On register stack architectures, don't GCSE constants from the
1163 constant pool, as the benefits are often swamped by the overhead
1164 of shuffling the register stack between basic blocks. */
1165 if (IS_STACK_MODE (GET_MODE (x
)))
1166 x
= avoid_constant_pool_reference (x
);
1169 switch (GET_CODE (x
))
1181 return can_assign_to_reg_p (x
);
1185 /* Used internally by can_assign_to_reg_p. */
1187 static GTY(()) rtx test_insn
;
1189 /* Return true if we can assign X to a pseudo register. */
1192 can_assign_to_reg_p (rtx x
)
1194 int num_clobbers
= 0;
1197 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1198 if (general_operand (x
, GET_MODE (x
)))
1200 else if (GET_MODE (x
) == VOIDmode
)
1203 /* Otherwise, check if we can make a valid insn from it. First initialize
1204 our test insn if we haven't already. */
1208 = make_insn_raw (gen_rtx_SET (VOIDmode
,
1209 gen_rtx_REG (word_mode
,
1210 FIRST_PSEUDO_REGISTER
* 2),
1212 NEXT_INSN (test_insn
) = PREV_INSN (test_insn
) = 0;
1215 /* Now make an insn like the one we would make when GCSE'ing and see if
1217 PUT_MODE (SET_DEST (PATTERN (test_insn
)), GET_MODE (x
));
1218 SET_SRC (PATTERN (test_insn
)) = x
;
1219 return ((icode
= recog (PATTERN (test_insn
), test_insn
, &num_clobbers
)) >= 0
1220 && (num_clobbers
== 0 || ! added_clobbers_hard_reg_p (icode
)));
1223 /* Return nonzero if the operands of expression X are unchanged from the
1224 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1225 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1228 oprs_unchanged_p (const_rtx x
, const_rtx insn
, int avail_p
)
1237 code
= GET_CODE (x
);
1242 struct reg_avail_info
*info
= ®_avail_info
[REGNO (x
)];
1244 if (info
->last_bb
!= current_bb
)
1247 return info
->last_set
< INSN_CUID (insn
);
1249 return info
->first_set
>= INSN_CUID (insn
);
1253 if (load_killed_in_block_p (current_bb
, INSN_CUID (insn
),
1257 return oprs_unchanged_p (XEXP (x
, 0), insn
, avail_p
);
1284 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
1288 /* If we are about to do the last recursive call needed at this
1289 level, change it into iteration. This function is called enough
1292 return oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
);
1294 else if (! oprs_unchanged_p (XEXP (x
, i
), insn
, avail_p
))
1297 else if (fmt
[i
] == 'E')
1298 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1299 if (! oprs_unchanged_p (XVECEXP (x
, i
, j
), insn
, avail_p
))
1306 /* Used for communication between mems_conflict_for_gcse_p and
1307 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1308 conflict between two memory references. */
1309 static int gcse_mems_conflict_p
;
1311 /* Used for communication between mems_conflict_for_gcse_p and
1312 load_killed_in_block_p. A memory reference for a load instruction,
1313 mems_conflict_for_gcse_p will see if a memory store conflicts with
1314 this memory load. */
1315 static const_rtx gcse_mem_operand
;
1317 /* DEST is the output of an instruction. If it is a memory reference, and
1318 possibly conflicts with the load found in gcse_mem_operand, then set
1319 gcse_mems_conflict_p to a nonzero value. */
1322 mems_conflict_for_gcse_p (rtx dest
, const_rtx setter ATTRIBUTE_UNUSED
,
1323 void *data ATTRIBUTE_UNUSED
)
1325 while (GET_CODE (dest
) == SUBREG
1326 || GET_CODE (dest
) == ZERO_EXTRACT
1327 || GET_CODE (dest
) == STRICT_LOW_PART
)
1328 dest
= XEXP (dest
, 0);
1330 /* If DEST is not a MEM, then it will not conflict with the load. Note
1331 that function calls are assumed to clobber memory, but are handled
1336 /* If we are setting a MEM in our list of specially recognized MEMs,
1337 don't mark as killed this time. */
1339 if (expr_equiv_p (dest
, gcse_mem_operand
) && pre_ldst_mems
!= NULL
)
1341 if (!find_rtx_in_ldst (dest
))
1342 gcse_mems_conflict_p
= 1;
1346 if (true_dependence (dest
, GET_MODE (dest
), gcse_mem_operand
,
1348 gcse_mems_conflict_p
= 1;
1351 /* Return nonzero if the expression in X (a memory reference) is killed
1352 in block BB before or after the insn with the CUID in UID_LIMIT.
1353 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1356 To check the entire block, set UID_LIMIT to max_uid + 1 and
1360 load_killed_in_block_p (const_basic_block bb
, int uid_limit
, const_rtx x
, int avail_p
)
1362 rtx list_entry
= modify_mem_list
[bb
->index
];
1364 /* If this is a readonly then we aren't going to be changing it. */
1365 if (MEM_READONLY_P (x
))
1371 /* Ignore entries in the list that do not apply. */
1373 && INSN_CUID (XEXP (list_entry
, 0)) < uid_limit
)
1375 && INSN_CUID (XEXP (list_entry
, 0)) > uid_limit
))
1377 list_entry
= XEXP (list_entry
, 1);
1381 setter
= XEXP (list_entry
, 0);
1383 /* If SETTER is a call everything is clobbered. Note that calls
1384 to pure functions are never put on the list, so we need not
1385 worry about them. */
1386 if (CALL_P (setter
))
1389 /* SETTER must be an INSN of some kind that sets memory. Call
1390 note_stores to examine each hunk of memory that is modified.
1392 The note_stores interface is pretty limited, so we have to
1393 communicate via global variables. Yuk. */
1394 gcse_mem_operand
= x
;
1395 gcse_mems_conflict_p
= 0;
1396 note_stores (PATTERN (setter
), mems_conflict_for_gcse_p
, NULL
);
1397 if (gcse_mems_conflict_p
)
1399 list_entry
= XEXP (list_entry
, 1);
1404 /* Return nonzero if the operands of expression X are unchanged from
1405 the start of INSN's basic block up to but not including INSN. */
1408 oprs_anticipatable_p (const_rtx x
, const_rtx insn
)
1410 return oprs_unchanged_p (x
, insn
, 0);
1413 /* Return nonzero if the operands of expression X are unchanged from
1414 INSN to the end of INSN's basic block. */
1417 oprs_available_p (const_rtx x
, const_rtx insn
)
1419 return oprs_unchanged_p (x
, insn
, 1);
1422 /* Hash expression X.
1424 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1425 indicating if a volatile operand is found or if the expression contains
1426 something we don't want to insert in the table. HASH_TABLE_SIZE is
1427 the current size of the hash table to be probed. */
1430 hash_expr (const_rtx x
, enum machine_mode mode
, int *do_not_record_p
,
1431 int hash_table_size
)
1435 *do_not_record_p
= 0;
1437 hash
= hash_rtx (x
, mode
, do_not_record_p
,
1438 NULL
, /*have_reg_qty=*/false);
1439 return hash
% hash_table_size
;
1442 /* Hash a set of register REGNO.
1444 Sets are hashed on the register that is set. This simplifies the PRE copy
1447 ??? May need to make things more elaborate. Later, as necessary. */
1450 hash_set (int regno
, int hash_table_size
)
1455 return hash
% hash_table_size
;
1458 /* Return nonzero if exp1 is equivalent to exp2. */
1461 expr_equiv_p (const_rtx x
, const_rtx y
)
1463 return exp_equiv_p (x
, y
, 0, true);
1466 /* Insert expression X in INSN in the hash TABLE.
1467 If it is already present, record it as the last occurrence in INSN's
1470 MODE is the mode of the value X is being stored into.
1471 It is only used if X is a CONST_INT.
1473 ANTIC_P is nonzero if X is an anticipatable expression.
1474 AVAIL_P is nonzero if X is an available expression. */
1477 insert_expr_in_table (rtx x
, enum machine_mode mode
, rtx insn
, int antic_p
,
1478 int avail_p
, struct hash_table
*table
)
1480 int found
, do_not_record_p
;
1482 struct expr
*cur_expr
, *last_expr
= NULL
;
1483 struct occr
*antic_occr
, *avail_occr
;
1485 hash
= hash_expr (x
, mode
, &do_not_record_p
, table
->size
);
1487 /* Do not insert expression in table if it contains volatile operands,
1488 or if hash_expr determines the expression is something we don't want
1489 to or can't handle. */
1490 if (do_not_record_p
)
1493 cur_expr
= table
->table
[hash
];
1496 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1498 /* If the expression isn't found, save a pointer to the end of
1500 last_expr
= cur_expr
;
1501 cur_expr
= cur_expr
->next_same_hash
;
1506 cur_expr
= gcse_alloc (sizeof (struct expr
));
1507 bytes_used
+= sizeof (struct expr
);
1508 if (table
->table
[hash
] == NULL
)
1509 /* This is the first pattern that hashed to this index. */
1510 table
->table
[hash
] = cur_expr
;
1512 /* Add EXPR to end of this hash chain. */
1513 last_expr
->next_same_hash
= cur_expr
;
1515 /* Set the fields of the expr element. */
1517 cur_expr
->bitmap_index
= table
->n_elems
++;
1518 cur_expr
->next_same_hash
= NULL
;
1519 cur_expr
->antic_occr
= NULL
;
1520 cur_expr
->avail_occr
= NULL
;
1523 /* Now record the occurrence(s). */
1526 antic_occr
= cur_expr
->antic_occr
;
1528 if (antic_occr
&& BLOCK_NUM (antic_occr
->insn
) != BLOCK_NUM (insn
))
1532 /* Found another instance of the expression in the same basic block.
1533 Prefer the currently recorded one. We want the first one in the
1534 block and the block is scanned from start to end. */
1535 ; /* nothing to do */
1538 /* First occurrence of this expression in this basic block. */
1539 antic_occr
= gcse_alloc (sizeof (struct occr
));
1540 bytes_used
+= sizeof (struct occr
);
1541 antic_occr
->insn
= insn
;
1542 antic_occr
->next
= cur_expr
->antic_occr
;
1543 antic_occr
->deleted_p
= 0;
1544 cur_expr
->antic_occr
= antic_occr
;
1550 avail_occr
= cur_expr
->avail_occr
;
1552 if (avail_occr
&& BLOCK_NUM (avail_occr
->insn
) == BLOCK_NUM (insn
))
1554 /* Found another instance of the expression in the same basic block.
1555 Prefer this occurrence to the currently recorded one. We want
1556 the last one in the block and the block is scanned from start
1558 avail_occr
->insn
= insn
;
1562 /* First occurrence of this expression in this basic block. */
1563 avail_occr
= gcse_alloc (sizeof (struct occr
));
1564 bytes_used
+= sizeof (struct occr
);
1565 avail_occr
->insn
= insn
;
1566 avail_occr
->next
= cur_expr
->avail_occr
;
1567 avail_occr
->deleted_p
= 0;
1568 cur_expr
->avail_occr
= avail_occr
;
1573 /* Insert pattern X in INSN in the hash table.
1574 X is a SET of a reg to either another reg or a constant.
1575 If it is already present, record it as the last occurrence in INSN's
1579 insert_set_in_table (rtx x
, rtx insn
, struct hash_table
*table
)
1583 struct expr
*cur_expr
, *last_expr
= NULL
;
1584 struct occr
*cur_occr
;
1586 gcc_assert (GET_CODE (x
) == SET
&& REG_P (SET_DEST (x
)));
1588 hash
= hash_set (REGNO (SET_DEST (x
)), table
->size
);
1590 cur_expr
= table
->table
[hash
];
1593 while (cur_expr
&& 0 == (found
= expr_equiv_p (cur_expr
->expr
, x
)))
1595 /* If the expression isn't found, save a pointer to the end of
1597 last_expr
= cur_expr
;
1598 cur_expr
= cur_expr
->next_same_hash
;
1603 cur_expr
= gcse_alloc (sizeof (struct expr
));
1604 bytes_used
+= sizeof (struct expr
);
1605 if (table
->table
[hash
] == NULL
)
1606 /* This is the first pattern that hashed to this index. */
1607 table
->table
[hash
] = cur_expr
;
1609 /* Add EXPR to end of this hash chain. */
1610 last_expr
->next_same_hash
= cur_expr
;
1612 /* Set the fields of the expr element.
1613 We must copy X because it can be modified when copy propagation is
1614 performed on its operands. */
1615 cur_expr
->expr
= copy_rtx (x
);
1616 cur_expr
->bitmap_index
= table
->n_elems
++;
1617 cur_expr
->next_same_hash
= NULL
;
1618 cur_expr
->antic_occr
= NULL
;
1619 cur_expr
->avail_occr
= NULL
;
1622 /* Now record the occurrence. */
1623 cur_occr
= cur_expr
->avail_occr
;
1625 if (cur_occr
&& BLOCK_NUM (cur_occr
->insn
) == BLOCK_NUM (insn
))
1627 /* Found another instance of the expression in the same basic block.
1628 Prefer this occurrence to the currently recorded one. We want
1629 the last one in the block and the block is scanned from start
1631 cur_occr
->insn
= insn
;
1635 /* First occurrence of this expression in this basic block. */
1636 cur_occr
= gcse_alloc (sizeof (struct occr
));
1637 bytes_used
+= sizeof (struct occr
);
1639 cur_occr
->insn
= insn
;
1640 cur_occr
->next
= cur_expr
->avail_occr
;
1641 cur_occr
->deleted_p
= 0;
1642 cur_expr
->avail_occr
= cur_occr
;
1646 /* Determine whether the rtx X should be treated as a constant for
1647 the purposes of GCSE's constant propagation. */
1650 gcse_constant_p (const_rtx x
)
1652 /* Consider a COMPARE of two integers constant. */
1653 if (GET_CODE (x
) == COMPARE
1654 && GET_CODE (XEXP (x
, 0)) == CONST_INT
1655 && GET_CODE (XEXP (x
, 1)) == CONST_INT
)
1658 /* Consider a COMPARE of the same registers is a constant
1659 if they are not floating point registers. */
1660 if (GET_CODE(x
) == COMPARE
1661 && REG_P (XEXP (x
, 0)) && REG_P (XEXP (x
, 1))
1662 && REGNO (XEXP (x
, 0)) == REGNO (XEXP (x
, 1))
1663 && ! FLOAT_MODE_P (GET_MODE (XEXP (x
, 0)))
1664 && ! FLOAT_MODE_P (GET_MODE (XEXP (x
, 1))))
1667 return CONSTANT_P (x
);
1670 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
1674 hash_scan_set (rtx pat
, rtx insn
, struct hash_table
*table
)
1676 rtx src
= SET_SRC (pat
);
1677 rtx dest
= SET_DEST (pat
);
1680 if (GET_CODE (src
) == CALL
)
1681 hash_scan_call (src
, insn
, table
);
1683 else if (REG_P (dest
))
1685 unsigned int regno
= REGNO (dest
);
1688 /* See if a REG_NOTE shows this equivalent to a simpler expression.
1689 This allows us to do a single GCSE pass and still eliminate
1690 redundant constants, addresses or other expressions that are
1691 constructed with multiple instructions. */
1692 note
= find_reg_equal_equiv_note (insn
);
1695 ? gcse_constant_p (XEXP (note
, 0))
1696 : want_to_gcse_p (XEXP (note
, 0))))
1697 src
= XEXP (note
, 0), pat
= gen_rtx_SET (VOIDmode
, dest
, src
);
1699 /* Only record sets of pseudo-regs in the hash table. */
1701 && regno
>= FIRST_PSEUDO_REGISTER
1702 /* Don't GCSE something if we can't do a reg/reg copy. */
1703 && can_copy_p (GET_MODE (dest
))
1704 /* GCSE commonly inserts instruction after the insn. We can't
1705 do that easily for EH_REGION notes so disable GCSE on these
1707 && !find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
1708 /* Is SET_SRC something we want to gcse? */
1709 && want_to_gcse_p (src
)
1710 /* Don't CSE a nop. */
1711 && ! set_noop_p (pat
)
1712 /* Don't GCSE if it has attached REG_EQUIV note.
1713 At this point this only function parameters should have
1714 REG_EQUIV notes and if the argument slot is used somewhere
1715 explicitly, it means address of parameter has been taken,
1716 so we should not extend the lifetime of the pseudo. */
1717 && (note
== NULL_RTX
|| ! MEM_P (XEXP (note
, 0))))
1719 /* An expression is not anticipatable if its operands are
1720 modified before this insn or if this is not the only SET in
1721 this insn. The latter condition does not have to mean that
1722 SRC itself is not anticipatable, but we just will not be
1723 able to handle code motion of insns with multiple sets. */
1724 int antic_p
= oprs_anticipatable_p (src
, insn
)
1725 && !multiple_sets (insn
);
1726 /* An expression is not available if its operands are
1727 subsequently modified, including this insn. It's also not
1728 available if this is a branch, because we can't insert
1729 a set after the branch. */
1730 int avail_p
= (oprs_available_p (src
, insn
)
1731 && ! JUMP_P (insn
));
1733 insert_expr_in_table (src
, GET_MODE (dest
), insn
, antic_p
, avail_p
, table
);
1736 /* Record sets for constant/copy propagation. */
1737 else if (table
->set_p
1738 && regno
>= FIRST_PSEUDO_REGISTER
1740 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
1741 && can_copy_p (GET_MODE (dest
))
1742 && REGNO (src
) != regno
)
1743 || gcse_constant_p (src
))
1744 /* A copy is not available if its src or dest is subsequently
1745 modified. Here we want to search from INSN+1 on, but
1746 oprs_available_p searches from INSN on. */
1747 && (insn
== BB_END (BLOCK_FOR_INSN (insn
))
1748 || (tmp
= next_nonnote_insn (insn
)) == NULL_RTX
1749 || BLOCK_FOR_INSN (tmp
) != BLOCK_FOR_INSN (insn
)
1750 || oprs_available_p (pat
, tmp
)))
1751 insert_set_in_table (pat
, insn
, table
);
1753 /* In case of store we want to consider the memory value as available in
1754 the REG stored in that memory. This makes it possible to remove
1755 redundant loads from due to stores to the same location. */
1756 else if (flag_gcse_las
&& REG_P (src
) && MEM_P (dest
))
1758 unsigned int regno
= REGNO (src
);
1760 /* Do not do this for constant/copy propagation. */
1762 /* Only record sets of pseudo-regs in the hash table. */
1763 && regno
>= FIRST_PSEUDO_REGISTER
1764 /* Don't GCSE something if we can't do a reg/reg copy. */
1765 && can_copy_p (GET_MODE (src
))
1766 /* GCSE commonly inserts instruction after the insn. We can't
1767 do that easily for EH_REGION notes so disable GCSE on these
1769 && ! find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
)
1770 /* Is SET_DEST something we want to gcse? */
1771 && want_to_gcse_p (dest
)
1772 /* Don't CSE a nop. */
1773 && ! set_noop_p (pat
)
1774 /* Don't GCSE if it has attached REG_EQUIV note.
1775 At this point this only function parameters should have
1776 REG_EQUIV notes and if the argument slot is used somewhere
1777 explicitly, it means address of parameter has been taken,
1778 so we should not extend the lifetime of the pseudo. */
1779 && ((note
= find_reg_note (insn
, REG_EQUIV
, NULL_RTX
)) == 0
1780 || ! MEM_P (XEXP (note
, 0))))
1782 /* Stores are never anticipatable. */
1784 /* An expression is not available if its operands are
1785 subsequently modified, including this insn. It's also not
1786 available if this is a branch, because we can't insert
1787 a set after the branch. */
1788 int avail_p
= oprs_available_p (dest
, insn
)
1791 /* Record the memory expression (DEST) in the hash table. */
1792 insert_expr_in_table (dest
, GET_MODE (dest
), insn
,
1793 antic_p
, avail_p
, table
);
1799 hash_scan_clobber (rtx x ATTRIBUTE_UNUSED
, rtx insn ATTRIBUTE_UNUSED
,
1800 struct hash_table
*table ATTRIBUTE_UNUSED
)
1802 /* Currently nothing to do. */
1806 hash_scan_call (rtx x ATTRIBUTE_UNUSED
, rtx insn ATTRIBUTE_UNUSED
,
1807 struct hash_table
*table ATTRIBUTE_UNUSED
)
1809 /* Currently nothing to do. */
1812 /* Process INSN and add hash table entries as appropriate.
1814 Only available expressions that set a single pseudo-reg are recorded.
1816 Single sets in a PARALLEL could be handled, but it's an extra complication
1817 that isn't dealt with right now. The trick is handling the CLOBBERs that
1818 are also in the PARALLEL. Later.
1820 If SET_P is nonzero, this is for the assignment hash table,
1821 otherwise it is for the expression hash table.
1822 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
1823 not record any expressions. */
1826 hash_scan_insn (rtx insn
, struct hash_table
*table
, int in_libcall_block
)
1828 rtx pat
= PATTERN (insn
);
1831 if (in_libcall_block
)
1834 /* Pick out the sets of INSN and for other forms of instructions record
1835 what's been modified. */
1837 if (GET_CODE (pat
) == SET
)
1838 hash_scan_set (pat
, insn
, table
);
1839 else if (GET_CODE (pat
) == PARALLEL
)
1840 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
1842 rtx x
= XVECEXP (pat
, 0, i
);
1844 if (GET_CODE (x
) == SET
)
1845 hash_scan_set (x
, insn
, table
);
1846 else if (GET_CODE (x
) == CLOBBER
)
1847 hash_scan_clobber (x
, insn
, table
);
1848 else if (GET_CODE (x
) == CALL
)
1849 hash_scan_call (x
, insn
, table
);
1852 else if (GET_CODE (pat
) == CLOBBER
)
1853 hash_scan_clobber (pat
, insn
, table
);
1854 else if (GET_CODE (pat
) == CALL
)
1855 hash_scan_call (pat
, insn
, table
);
1859 dump_hash_table (FILE *file
, const char *name
, struct hash_table
*table
)
1862 /* Flattened out table, so it's printed in proper order. */
1863 struct expr
**flat_table
;
1864 unsigned int *hash_val
;
1867 flat_table
= xcalloc (table
->n_elems
, sizeof (struct expr
*));
1868 hash_val
= xmalloc (table
->n_elems
* sizeof (unsigned int));
1870 for (i
= 0; i
< (int) table
->size
; i
++)
1871 for (expr
= table
->table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
1873 flat_table
[expr
->bitmap_index
] = expr
;
1874 hash_val
[expr
->bitmap_index
] = i
;
1877 fprintf (file
, "%s hash table (%d buckets, %d entries)\n",
1878 name
, table
->size
, table
->n_elems
);
1880 for (i
= 0; i
< (int) table
->n_elems
; i
++)
1881 if (flat_table
[i
] != 0)
1883 expr
= flat_table
[i
];
1884 fprintf (file
, "Index %d (hash value %d)\n ",
1885 expr
->bitmap_index
, hash_val
[i
]);
1886 print_rtl (file
, expr
->expr
);
1887 fprintf (file
, "\n");
1890 fprintf (file
, "\n");
1896 /* Record register first/last/block set information for REGNO in INSN.
1898 first_set records the first place in the block where the register
1899 is set and is used to compute "anticipatability".
1901 last_set records the last place in the block where the register
1902 is set and is used to compute "availability".
1904 last_bb records the block for which first_set and last_set are
1905 valid, as a quick test to invalidate them.
1907 reg_set_in_block records whether the register is set in the block
1908 and is used to compute "transparency". */
1911 record_last_reg_set_info (rtx insn
, int regno
)
1913 struct reg_avail_info
*info
= ®_avail_info
[regno
];
1914 int cuid
= INSN_CUID (insn
);
1916 info
->last_set
= cuid
;
1917 if (info
->last_bb
!= current_bb
)
1919 info
->last_bb
= current_bb
;
1920 info
->first_set
= cuid
;
1921 SET_BIT (reg_set_in_block
[current_bb
->index
], regno
);
1926 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
1927 Note we store a pair of elements in the list, so they have to be
1928 taken off pairwise. */
1931 canon_list_insert (rtx dest ATTRIBUTE_UNUSED
, const_rtx unused1 ATTRIBUTE_UNUSED
,
1934 rtx dest_addr
, insn
;
1937 while (GET_CODE (dest
) == SUBREG
1938 || GET_CODE (dest
) == ZERO_EXTRACT
1939 || GET_CODE (dest
) == STRICT_LOW_PART
)
1940 dest
= XEXP (dest
, 0);
1942 /* If DEST is not a MEM, then it will not conflict with a load. Note
1943 that function calls are assumed to clobber memory, but are handled
1949 dest_addr
= get_addr (XEXP (dest
, 0));
1950 dest_addr
= canon_rtx (dest_addr
);
1951 insn
= (rtx
) v_insn
;
1952 bb
= BLOCK_NUM (insn
);
1954 canon_modify_mem_list
[bb
] =
1955 alloc_EXPR_LIST (VOIDmode
, dest_addr
, canon_modify_mem_list
[bb
]);
1956 canon_modify_mem_list
[bb
] =
1957 alloc_EXPR_LIST (VOIDmode
, dest
, canon_modify_mem_list
[bb
]);
1960 /* Record memory modification information for INSN. We do not actually care
1961 about the memory location(s) that are set, or even how they are set (consider
1962 a CALL_INSN). We merely need to record which insns modify memory. */
1965 record_last_mem_set_info (rtx insn
)
1967 int bb
= BLOCK_NUM (insn
);
1969 /* load_killed_in_block_p will handle the case of calls clobbering
1971 modify_mem_list
[bb
] = alloc_INSN_LIST (insn
, modify_mem_list
[bb
]);
1972 bitmap_set_bit (modify_mem_list_set
, bb
);
1976 /* Note that traversals of this loop (other than for free-ing)
1977 will break after encountering a CALL_INSN. So, there's no
1978 need to insert a pair of items, as canon_list_insert does. */
1979 canon_modify_mem_list
[bb
] =
1980 alloc_INSN_LIST (insn
, canon_modify_mem_list
[bb
]);
1981 bitmap_set_bit (blocks_with_calls
, bb
);
1984 note_stores (PATTERN (insn
), canon_list_insert
, (void*) insn
);
1987 /* Called from compute_hash_table via note_stores to handle one
1988 SET or CLOBBER in an insn. DATA is really the instruction in which
1989 the SET is taking place. */
1992 record_last_set_info (rtx dest
, const_rtx setter ATTRIBUTE_UNUSED
, void *data
)
1994 rtx last_set_insn
= (rtx
) data
;
1996 if (GET_CODE (dest
) == SUBREG
)
1997 dest
= SUBREG_REG (dest
);
2000 record_last_reg_set_info (last_set_insn
, REGNO (dest
));
2001 else if (MEM_P (dest
)
2002 /* Ignore pushes, they clobber nothing. */
2003 && ! push_operand (dest
, GET_MODE (dest
)))
2004 record_last_mem_set_info (last_set_insn
);
2007 /* Top level function to create an expression or assignment hash table.
2009 Expression entries are placed in the hash table if
2010 - they are of the form (set (pseudo-reg) src),
2011 - src is something we want to perform GCSE on,
2012 - none of the operands are subsequently modified in the block
2014 Assignment entries are placed in the hash table if
2015 - they are of the form (set (pseudo-reg) src),
2016 - src is something we want to perform const/copy propagation on,
2017 - none of the operands or target are subsequently modified in the block
2019 Currently src must be a pseudo-reg or a const_int.
2021 TABLE is the table computed. */
2024 compute_hash_table_work (struct hash_table
*table
)
2028 /* While we compute the hash table we also compute a bit array of which
2029 registers are set in which blocks.
2030 ??? This isn't needed during const/copy propagation, but it's cheap to
2032 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
2034 /* re-Cache any INSN_LIST nodes we have allocated. */
2035 clear_modify_mem_tables ();
2036 /* Some working arrays used to track first and last set in each block. */
2037 reg_avail_info
= gmalloc (max_gcse_regno
* sizeof (struct reg_avail_info
));
2039 for (i
= 0; i
< max_gcse_regno
; ++i
)
2040 reg_avail_info
[i
].last_bb
= NULL
;
2042 FOR_EACH_BB (current_bb
)
2046 int in_libcall_block
;
2048 /* First pass over the instructions records information used to
2049 determine when registers and memory are first and last set.
2050 ??? hard-reg reg_set_in_block computation
2051 could be moved to compute_sets since they currently don't change. */
2053 FOR_BB_INSNS (current_bb
, insn
)
2055 if (! INSN_P (insn
))
2060 HARD_REG_SET clobbered_regs
;
2062 get_call_invalidated_used_regs (insn
, &clobbered_regs
, true);
2063 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2064 if (TEST_HARD_REG_BIT (clobbered_regs
, regno
))
2065 record_last_reg_set_info (insn
, regno
);
2070 note_stores (PATTERN (insn
), record_last_set_info
, insn
);
2073 /* Insert implicit sets in the hash table. */
2075 && implicit_sets
[current_bb
->index
] != NULL_RTX
)
2076 hash_scan_set (implicit_sets
[current_bb
->index
],
2077 BB_HEAD (current_bb
), table
);
2079 /* The next pass builds the hash table. */
2080 in_libcall_block
= 0;
2081 FOR_BB_INSNS (current_bb
, insn
)
2084 if (find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
2085 in_libcall_block
= 1;
2086 else if (table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2087 in_libcall_block
= 0;
2088 hash_scan_insn (insn
, table
, in_libcall_block
);
2089 if (!table
->set_p
&& find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
2090 in_libcall_block
= 0;
2094 free (reg_avail_info
);
2095 reg_avail_info
= NULL
;
2098 /* Allocate space for the set/expr hash TABLE.
2099 N_INSNS is the number of instructions in the function.
2100 It is used to determine the number of buckets to use.
2101 SET_P determines whether set or expression table will
2105 alloc_hash_table (int n_insns
, struct hash_table
*table
, int set_p
)
2109 table
->size
= n_insns
/ 4;
2110 if (table
->size
< 11)
2113 /* Attempt to maintain efficient use of hash table.
2114 Making it an odd number is simplest for now.
2115 ??? Later take some measurements. */
2117 n
= table
->size
* sizeof (struct expr
*);
2118 table
->table
= gmalloc (n
);
2119 table
->set_p
= set_p
;
2122 /* Free things allocated by alloc_hash_table. */
2125 free_hash_table (struct hash_table
*table
)
2127 free (table
->table
);
2130 /* Compute the hash TABLE for doing copy/const propagation or
2131 expression hash table. */
2134 compute_hash_table (struct hash_table
*table
)
2136 /* Initialize count of number of entries in hash table. */
2138 memset (table
->table
, 0, table
->size
* sizeof (struct expr
*));
2140 compute_hash_table_work (table
);
2143 /* Expression tracking support. */
2145 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2146 table entry, or NULL if not found. */
2148 static struct expr
*
2149 lookup_set (unsigned int regno
, struct hash_table
*table
)
2151 unsigned int hash
= hash_set (regno
, table
->size
);
2154 expr
= table
->table
[hash
];
2156 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
)
2157 expr
= expr
->next_same_hash
;
2162 /* Return the next entry for REGNO in list EXPR. */
2164 static struct expr
*
2165 next_set (unsigned int regno
, struct expr
*expr
)
2168 expr
= expr
->next_same_hash
;
2169 while (expr
&& REGNO (SET_DEST (expr
->expr
)) != regno
);
2174 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2175 types may be mixed. */
2178 free_insn_expr_list_list (rtx
*listp
)
2182 for (list
= *listp
; list
; list
= next
)
2184 next
= XEXP (list
, 1);
2185 if (GET_CODE (list
) == EXPR_LIST
)
2186 free_EXPR_LIST_node (list
);
2188 free_INSN_LIST_node (list
);
2194 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2196 clear_modify_mem_tables (void)
2201 EXECUTE_IF_SET_IN_BITMAP (modify_mem_list_set
, 0, i
, bi
)
2203 free_INSN_LIST_list (modify_mem_list
+ i
);
2204 free_insn_expr_list_list (canon_modify_mem_list
+ i
);
2206 bitmap_clear (modify_mem_list_set
);
2207 bitmap_clear (blocks_with_calls
);
2210 /* Release memory used by modify_mem_list_set. */
2213 free_modify_mem_tables (void)
2215 clear_modify_mem_tables ();
2216 free (modify_mem_list
);
2217 free (canon_modify_mem_list
);
2218 modify_mem_list
= 0;
2219 canon_modify_mem_list
= 0;
2222 /* Reset tables used to keep track of what's still available [since the
2223 start of the block]. */
2226 reset_opr_set_tables (void)
2228 /* Maintain a bitmap of which regs have been set since beginning of
2230 CLEAR_REG_SET (reg_set_bitmap
);
2232 /* Also keep a record of the last instruction to modify memory.
2233 For now this is very trivial, we only record whether any memory
2234 location has been modified. */
2235 clear_modify_mem_tables ();
2238 /* Return nonzero if the operands of X are not set before INSN in
2239 INSN's basic block. */
2242 oprs_not_set_p (const_rtx x
, const_rtx insn
)
2251 code
= GET_CODE (x
);
2268 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn
),
2269 INSN_CUID (insn
), x
, 0))
2272 return oprs_not_set_p (XEXP (x
, 0), insn
);
2275 return ! REGNO_REG_SET_P (reg_set_bitmap
, REGNO (x
));
2281 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2285 /* If we are about to do the last recursive call
2286 needed at this level, change it into iteration.
2287 This function is called enough to be worth it. */
2289 return oprs_not_set_p (XEXP (x
, i
), insn
);
2291 if (! oprs_not_set_p (XEXP (x
, i
), insn
))
2294 else if (fmt
[i
] == 'E')
2295 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2296 if (! oprs_not_set_p (XVECEXP (x
, i
, j
), insn
))
2303 /* Mark things set by a CALL. */
2306 mark_call (rtx insn
)
2308 if (! CONST_OR_PURE_CALL_P (insn
))
2309 record_last_mem_set_info (insn
);
2312 /* Mark things set by a SET. */
2315 mark_set (rtx pat
, rtx insn
)
2317 rtx dest
= SET_DEST (pat
);
2319 while (GET_CODE (dest
) == SUBREG
2320 || GET_CODE (dest
) == ZERO_EXTRACT
2321 || GET_CODE (dest
) == STRICT_LOW_PART
)
2322 dest
= XEXP (dest
, 0);
2325 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (dest
));
2326 else if (MEM_P (dest
))
2327 record_last_mem_set_info (insn
);
2329 if (GET_CODE (SET_SRC (pat
)) == CALL
)
2333 /* Record things set by a CLOBBER. */
2336 mark_clobber (rtx pat
, rtx insn
)
2338 rtx clob
= XEXP (pat
, 0);
2340 while (GET_CODE (clob
) == SUBREG
|| GET_CODE (clob
) == STRICT_LOW_PART
)
2341 clob
= XEXP (clob
, 0);
2344 SET_REGNO_REG_SET (reg_set_bitmap
, REGNO (clob
));
2346 record_last_mem_set_info (insn
);
2349 /* Record things set by INSN.
2350 This data is used by oprs_not_set_p. */
2353 mark_oprs_set (rtx insn
)
2355 rtx pat
= PATTERN (insn
);
2358 if (GET_CODE (pat
) == SET
)
2359 mark_set (pat
, insn
);
2360 else if (GET_CODE (pat
) == PARALLEL
)
2361 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
2363 rtx x
= XVECEXP (pat
, 0, i
);
2365 if (GET_CODE (x
) == SET
)
2367 else if (GET_CODE (x
) == CLOBBER
)
2368 mark_clobber (x
, insn
);
2369 else if (GET_CODE (x
) == CALL
)
2373 else if (GET_CODE (pat
) == CLOBBER
)
2374 mark_clobber (pat
, insn
);
2375 else if (GET_CODE (pat
) == CALL
)
2380 /* Compute copy/constant propagation working variables. */
2382 /* Local properties of assignments. */
2383 static sbitmap
*cprop_pavloc
;
2384 static sbitmap
*cprop_absaltered
;
2386 /* Global properties of assignments (computed from the local properties). */
2387 static sbitmap
*cprop_avin
;
2388 static sbitmap
*cprop_avout
;
2390 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
2391 basic blocks. N_SETS is the number of sets. */
2394 alloc_cprop_mem (int n_blocks
, int n_sets
)
2396 cprop_pavloc
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2397 cprop_absaltered
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2399 cprop_avin
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2400 cprop_avout
= sbitmap_vector_alloc (n_blocks
, n_sets
);
2403 /* Free vars used by copy/const propagation. */
2406 free_cprop_mem (void)
2408 sbitmap_vector_free (cprop_pavloc
);
2409 sbitmap_vector_free (cprop_absaltered
);
2410 sbitmap_vector_free (cprop_avin
);
2411 sbitmap_vector_free (cprop_avout
);
2414 /* For each block, compute whether X is transparent. X is either an
2415 expression or an assignment [though we don't care which, for this context
2416 an assignment is treated as an expression]. For each block where an
2417 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
2421 compute_transp (const_rtx x
, int indx
, sbitmap
*bmap
, int set_p
)
2429 /* repeat is used to turn tail-recursion into iteration since GCC
2430 can't do it when there's no return value. */
2436 code
= GET_CODE (x
);
2442 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
2445 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
2446 SET_BIT (bmap
[bb
->index
], indx
);
2450 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
2451 SET_BIT (bmap
[r
->bb_index
], indx
);
2456 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
)
2459 if (TEST_BIT (reg_set_in_block
[bb
->index
], REGNO (x
)))
2460 RESET_BIT (bmap
[bb
->index
], indx
);
2464 for (r
= reg_set_table
[REGNO (x
)]; r
!= NULL
; r
= r
->next
)
2465 RESET_BIT (bmap
[r
->bb_index
], indx
);
2472 if (! MEM_READONLY_P (x
))
2477 /* First handle all the blocks with calls. We don't need to
2478 do any list walking for them. */
2479 EXECUTE_IF_SET_IN_BITMAP (blocks_with_calls
, 0, bb_index
, bi
)
2482 SET_BIT (bmap
[bb_index
], indx
);
2484 RESET_BIT (bmap
[bb_index
], indx
);
2487 /* Now iterate over the blocks which have memory modifications
2488 but which do not have any calls. */
2489 EXECUTE_IF_AND_COMPL_IN_BITMAP (modify_mem_list_set
,
2493 rtx list_entry
= canon_modify_mem_list
[bb_index
];
2497 rtx dest
, dest_addr
;
2499 /* LIST_ENTRY must be an INSN of some kind that sets memory.
2500 Examine each hunk of memory that is modified. */
2502 dest
= XEXP (list_entry
, 0);
2503 list_entry
= XEXP (list_entry
, 1);
2504 dest_addr
= XEXP (list_entry
, 0);
2506 if (canon_true_dependence (dest
, GET_MODE (dest
), dest_addr
,
2507 x
, rtx_addr_varies_p
))
2510 SET_BIT (bmap
[bb_index
], indx
);
2512 RESET_BIT (bmap
[bb_index
], indx
);
2515 list_entry
= XEXP (list_entry
, 1);
2540 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2544 /* If we are about to do the last recursive call
2545 needed at this level, change it into iteration.
2546 This function is called enough to be worth it. */
2553 compute_transp (XEXP (x
, i
), indx
, bmap
, set_p
);
2555 else if (fmt
[i
] == 'E')
2556 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2557 compute_transp (XVECEXP (x
, i
, j
), indx
, bmap
, set_p
);
2561 /* Top level routine to do the dataflow analysis needed by copy/const
2565 compute_cprop_data (void)
2567 compute_local_properties (cprop_absaltered
, cprop_pavloc
, NULL
, &set_hash_table
);
2568 compute_available (cprop_pavloc
, cprop_absaltered
,
2569 cprop_avout
, cprop_avin
);
2572 /* Copy/constant propagation. */
2574 /* Maximum number of register uses in an insn that we handle. */
2577 /* Table of uses found in an insn.
2578 Allocated statically to avoid alloc/free complexity and overhead. */
2579 static struct reg_use reg_use_table
[MAX_USES
];
2581 /* Index into `reg_use_table' while building it. */
2582 static int reg_use_count
;
2584 /* Set up a list of register numbers used in INSN. The found uses are stored
2585 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
2586 and contains the number of uses in the table upon exit.
2588 ??? If a register appears multiple times we will record it multiple times.
2589 This doesn't hurt anything but it will slow things down. */
2592 find_used_regs (rtx
*xptr
, void *data ATTRIBUTE_UNUSED
)
2599 /* repeat is used to turn tail-recursion into iteration since GCC
2600 can't do it when there's no return value. */
2605 code
= GET_CODE (x
);
2608 if (reg_use_count
== MAX_USES
)
2611 reg_use_table
[reg_use_count
].reg_rtx
= x
;
2615 /* Recursively scan the operands of this expression. */
2617 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
2621 /* If we are about to do the last recursive call
2622 needed at this level, change it into iteration.
2623 This function is called enough to be worth it. */
2630 find_used_regs (&XEXP (x
, i
), data
);
2632 else if (fmt
[i
] == 'E')
2633 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2634 find_used_regs (&XVECEXP (x
, i
, j
), data
);
2638 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
2639 Returns nonzero is successful. */
2642 try_replace_reg (rtx from
, rtx to
, rtx insn
)
2644 rtx note
= find_reg_equal_equiv_note (insn
);
2647 rtx set
= single_set (insn
);
2649 /* Usually we substitute easy stuff, so we won't copy everything.
2650 We however need to take care to not duplicate non-trivial CONST
2654 validate_replace_src_group (from
, to
, insn
);
2655 if (num_changes_pending () && apply_change_group ())
2658 /* Try to simplify SET_SRC if we have substituted a constant. */
2659 if (success
&& set
&& CONSTANT_P (to
))
2661 src
= simplify_rtx (SET_SRC (set
));
2664 validate_change (insn
, &SET_SRC (set
), src
, 0);
2667 /* If there is already a REG_EQUAL note, update the expression in it
2668 with our replacement. */
2669 if (note
!= 0 && REG_NOTE_KIND (note
) == REG_EQUAL
)
2670 set_unique_reg_note (insn
, REG_EQUAL
,
2671 simplify_replace_rtx (XEXP (note
, 0), from
,
2673 if (!success
&& set
&& reg_mentioned_p (from
, SET_SRC (set
)))
2675 /* If above failed and this is a single set, try to simplify the source of
2676 the set given our substitution. We could perhaps try this for multiple
2677 SETs, but it probably won't buy us anything. */
2678 src
= simplify_replace_rtx (SET_SRC (set
), from
, to
);
2680 if (!rtx_equal_p (src
, SET_SRC (set
))
2681 && validate_change (insn
, &SET_SRC (set
), src
, 0))
2684 /* If we've failed to do replacement, have a single SET, don't already
2685 have a note, and have no special SET, add a REG_EQUAL note to not
2686 lose information. */
2687 if (!success
&& note
== 0 && set
!= 0
2688 && GET_CODE (SET_DEST (set
)) != ZERO_EXTRACT
2689 && GET_CODE (SET_DEST (set
)) != STRICT_LOW_PART
)
2690 note
= set_unique_reg_note (insn
, REG_EQUAL
, copy_rtx (src
));
2693 /* REG_EQUAL may get simplified into register.
2694 We don't allow that. Remove that note. This code ought
2695 not to happen, because previous code ought to synthesize
2696 reg-reg move, but be on the safe side. */
2697 if (note
&& REG_NOTE_KIND (note
) == REG_EQUAL
&& REG_P (XEXP (note
, 0)))
2698 remove_note (insn
, note
);
2703 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
2704 NULL no such set is found. */
2706 static struct expr
*
2707 find_avail_set (int regno
, rtx insn
)
2709 /* SET1 contains the last set found that can be returned to the caller for
2710 use in a substitution. */
2711 struct expr
*set1
= 0;
2713 /* Loops are not possible here. To get a loop we would need two sets
2714 available at the start of the block containing INSN. i.e. we would
2715 need two sets like this available at the start of the block:
2717 (set (reg X) (reg Y))
2718 (set (reg Y) (reg X))
2720 This can not happen since the set of (reg Y) would have killed the
2721 set of (reg X) making it unavailable at the start of this block. */
2725 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
2727 /* Find a set that is available at the start of the block
2728 which contains INSN. */
2731 if (TEST_BIT (cprop_avin
[BLOCK_NUM (insn
)], set
->bitmap_index
))
2733 set
= next_set (regno
, set
);
2736 /* If no available set was found we've reached the end of the
2737 (possibly empty) copy chain. */
2741 gcc_assert (GET_CODE (set
->expr
) == SET
);
2743 src
= SET_SRC (set
->expr
);
2745 /* We know the set is available.
2746 Now check that SRC is ANTLOC (i.e. none of the source operands
2747 have changed since the start of the block).
2749 If the source operand changed, we may still use it for the next
2750 iteration of this loop, but we may not use it for substitutions. */
2752 if (gcse_constant_p (src
) || oprs_not_set_p (src
, insn
))
2755 /* If the source of the set is anything except a register, then
2756 we have reached the end of the copy chain. */
2760 /* Follow the copy chain, i.e. start another iteration of the loop
2761 and see if we have an available copy into SRC. */
2762 regno
= REGNO (src
);
2765 /* SET1 holds the last set that was available and anticipatable at
2770 /* Subroutine of cprop_insn that tries to propagate constants into
2771 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
2772 it is the instruction that immediately precedes JUMP, and must be a
2773 single SET of a register. FROM is what we will try to replace,
2774 SRC is the constant we will try to substitute for it. Returns nonzero
2775 if a change was made. */
2778 cprop_jump (basic_block bb
, rtx setcc
, rtx jump
, rtx from
, rtx src
)
2780 rtx
new, set_src
, note_src
;
2781 rtx set
= pc_set (jump
);
2782 rtx note
= find_reg_equal_equiv_note (jump
);
2786 note_src
= XEXP (note
, 0);
2787 if (GET_CODE (note_src
) == EXPR_LIST
)
2788 note_src
= NULL_RTX
;
2790 else note_src
= NULL_RTX
;
2792 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
2793 set_src
= note_src
? note_src
: SET_SRC (set
);
2795 /* First substitute the SETCC condition into the JUMP instruction,
2796 then substitute that given values into this expanded JUMP. */
2797 if (setcc
!= NULL_RTX
2798 && !modified_between_p (from
, setcc
, jump
)
2799 && !modified_between_p (src
, setcc
, jump
))
2802 rtx setcc_set
= single_set (setcc
);
2803 rtx setcc_note
= find_reg_equal_equiv_note (setcc
);
2804 setcc_src
= (setcc_note
&& GET_CODE (XEXP (setcc_note
, 0)) != EXPR_LIST
)
2805 ? XEXP (setcc_note
, 0) : SET_SRC (setcc_set
);
2806 set_src
= simplify_replace_rtx (set_src
, SET_DEST (setcc_set
),
2812 new = simplify_replace_rtx (set_src
, from
, src
);
2814 /* If no simplification can be made, then try the next register. */
2815 if (rtx_equal_p (new, SET_SRC (set
)))
2818 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
2823 /* Ensure the value computed inside the jump insn to be equivalent
2824 to one computed by setcc. */
2825 if (setcc
&& modified_in_p (new, setcc
))
2827 if (! validate_unshare_change (jump
, &SET_SRC (set
), new, 0))
2829 /* When (some) constants are not valid in a comparison, and there
2830 are two registers to be replaced by constants before the entire
2831 comparison can be folded into a constant, we need to keep
2832 intermediate information in REG_EQUAL notes. For targets with
2833 separate compare insns, such notes are added by try_replace_reg.
2834 When we have a combined compare-and-branch instruction, however,
2835 we need to attach a note to the branch itself to make this
2836 optimization work. */
2838 if (!rtx_equal_p (new, note_src
))
2839 set_unique_reg_note (jump
, REG_EQUAL
, copy_rtx (new));
2843 /* Remove REG_EQUAL note after simplification. */
2845 remove_note (jump
, note
);
2849 /* Delete the cc0 setter. */
2850 if (setcc
!= NULL
&& CC0_P (SET_DEST (single_set (setcc
))))
2851 delete_insn (setcc
);
2854 run_jump_opt_after_gcse
= 1;
2856 global_const_prop_count
++;
2857 if (dump_file
!= NULL
)
2860 "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
2861 REGNO (from
), INSN_UID (jump
));
2862 print_rtl (dump_file
, src
);
2863 fprintf (dump_file
, "\n");
2865 purge_dead_edges (bb
);
2867 /* If a conditional jump has been changed into unconditional jump, remove
2868 the jump and make the edge fallthru - this is always called in
2870 if (new != pc_rtx
&& simplejump_p (jump
))
2875 for (ei
= ei_start (bb
->succs
); (e
= ei_safe_edge (ei
)); ei_next (&ei
))
2876 if (e
->dest
!= EXIT_BLOCK_PTR
2877 && BB_HEAD (e
->dest
) == JUMP_LABEL (jump
))
2879 e
->flags
|= EDGE_FALLTHRU
;
2889 constprop_register (rtx insn
, rtx from
, rtx to
, bool alter_jumps
)
2893 /* Check for reg or cc0 setting instructions followed by
2894 conditional branch instructions first. */
2896 && (sset
= single_set (insn
)) != NULL
2898 && any_condjump_p (NEXT_INSN (insn
)) && onlyjump_p (NEXT_INSN (insn
)))
2900 rtx dest
= SET_DEST (sset
);
2901 if ((REG_P (dest
) || CC0_P (dest
))
2902 && cprop_jump (BLOCK_FOR_INSN (insn
), insn
, NEXT_INSN (insn
), from
, to
))
2906 /* Handle normal insns next. */
2907 if (NONJUMP_INSN_P (insn
)
2908 && try_replace_reg (from
, to
, insn
))
2911 /* Try to propagate a CONST_INT into a conditional jump.
2912 We're pretty specific about what we will handle in this
2913 code, we can extend this as necessary over time.
2915 Right now the insn in question must look like
2916 (set (pc) (if_then_else ...)) */
2917 else if (alter_jumps
&& any_condjump_p (insn
) && onlyjump_p (insn
))
2918 return cprop_jump (BLOCK_FOR_INSN (insn
), NULL
, insn
, from
, to
);
2922 /* Perform constant and copy propagation on INSN.
2923 The result is nonzero if a change was made. */
2926 cprop_insn (rtx insn
, int alter_jumps
)
2928 struct reg_use
*reg_used
;
2936 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
2938 note
= find_reg_equal_equiv_note (insn
);
2940 /* We may win even when propagating constants into notes. */
2942 find_used_regs (&XEXP (note
, 0), NULL
);
2944 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
2945 reg_used
++, reg_use_count
--)
2947 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
2951 /* Ignore registers created by GCSE.
2952 We do this because ... */
2953 if (regno
>= max_gcse_regno
)
2956 /* If the register has already been set in this block, there's
2957 nothing we can do. */
2958 if (! oprs_not_set_p (reg_used
->reg_rtx
, insn
))
2961 /* Find an assignment that sets reg_used and is available
2962 at the start of the block. */
2963 set
= find_avail_set (regno
, insn
);
2968 /* ??? We might be able to handle PARALLELs. Later. */
2969 gcc_assert (GET_CODE (pat
) == SET
);
2971 src
= SET_SRC (pat
);
2973 /* Constant propagation. */
2974 if (gcse_constant_p (src
))
2976 if (constprop_register (insn
, reg_used
->reg_rtx
, src
, alter_jumps
))
2979 global_const_prop_count
++;
2980 if (dump_file
!= NULL
)
2982 fprintf (dump_file
, "GLOBAL CONST-PROP: Replacing reg %d in ", regno
);
2983 fprintf (dump_file
, "insn %d with constant ", INSN_UID (insn
));
2984 print_rtl (dump_file
, src
);
2985 fprintf (dump_file
, "\n");
2987 if (INSN_DELETED_P (insn
))
2991 else if (REG_P (src
)
2992 && REGNO (src
) >= FIRST_PSEUDO_REGISTER
2993 && REGNO (src
) != regno
)
2995 if (try_replace_reg (reg_used
->reg_rtx
, src
, insn
))
2998 global_copy_prop_count
++;
2999 if (dump_file
!= NULL
)
3001 fprintf (dump_file
, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
3002 regno
, INSN_UID (insn
));
3003 fprintf (dump_file
, " with reg %d\n", REGNO (src
));
3006 /* The original insn setting reg_used may or may not now be
3007 deletable. We leave the deletion to flow. */
3008 /* FIXME: If it turns out that the insn isn't deletable,
3009 then we may have unnecessarily extended register lifetimes
3010 and made things worse. */
3018 /* Like find_used_regs, but avoid recording uses that appear in
3019 input-output contexts such as zero_extract or pre_dec. This
3020 restricts the cases we consider to those for which local cprop
3021 can legitimately make replacements. */
3024 local_cprop_find_used_regs (rtx
*xptr
, void *data
)
3031 switch (GET_CODE (x
))
3035 case STRICT_LOW_PART
:
3044 /* Can only legitimately appear this early in the context of
3045 stack pushes for function arguments, but handle all of the
3046 codes nonetheless. */
3050 /* Setting a subreg of a register larger than word_mode leaves
3051 the non-written words unchanged. */
3052 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x
))) > BITS_PER_WORD
)
3060 find_used_regs (xptr
, data
);
3063 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3064 their REG_EQUAL notes need updating. */
3067 do_local_cprop (rtx x
, rtx insn
, bool alter_jumps
, rtx
*libcall_sp
)
3069 rtx newreg
= NULL
, newcnst
= NULL
;
3071 /* Rule out USE instructions and ASM statements as we don't want to
3072 change the hard registers mentioned. */
3074 && (REGNO (x
) >= FIRST_PSEUDO_REGISTER
3075 || (GET_CODE (PATTERN (insn
)) != USE
3076 && asm_noperands (PATTERN (insn
)) < 0)))
3078 cselib_val
*val
= cselib_lookup (x
, GET_MODE (x
), 0);
3079 struct elt_loc_list
*l
;
3083 for (l
= val
->locs
; l
; l
= l
->next
)
3085 rtx this_rtx
= l
->loc
;
3088 /* Don't CSE non-constant values out of libcall blocks. */
3089 if (l
->in_libcall
&& ! CONSTANT_P (this_rtx
))
3092 if (gcse_constant_p (this_rtx
))
3094 if (REG_P (this_rtx
) && REGNO (this_rtx
) >= FIRST_PSEUDO_REGISTER
3095 /* Don't copy propagate if it has attached REG_EQUIV note.
3096 At this point this only function parameters should have
3097 REG_EQUIV notes and if the argument slot is used somewhere
3098 explicitly, it means address of parameter has been taken,
3099 so we should not extend the lifetime of the pseudo. */
3100 && (!(note
= find_reg_note (l
->setting_insn
, REG_EQUIV
, NULL_RTX
))
3101 || ! MEM_P (XEXP (note
, 0))))
3104 if (newcnst
&& constprop_register (insn
, x
, newcnst
, alter_jumps
))
3106 /* If we find a case where we can't fix the retval REG_EQUAL notes
3107 match the new register, we either have to abandon this replacement
3108 or fix delete_trivially_dead_insns to preserve the setting insn,
3109 or make it delete the REG_EQUAL note, and fix up all passes that
3110 require the REG_EQUAL note there. */
3113 adjusted
= adjust_libcall_notes (x
, newcnst
, insn
, libcall_sp
);
3114 gcc_assert (adjusted
);
3116 if (dump_file
!= NULL
)
3118 fprintf (dump_file
, "LOCAL CONST-PROP: Replacing reg %d in ",
3120 fprintf (dump_file
, "insn %d with constant ",
3122 print_rtl (dump_file
, newcnst
);
3123 fprintf (dump_file
, "\n");
3125 local_const_prop_count
++;
3128 else if (newreg
&& newreg
!= x
&& try_replace_reg (x
, newreg
, insn
))
3130 adjust_libcall_notes (x
, newreg
, insn
, libcall_sp
);
3131 if (dump_file
!= NULL
)
3134 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
3135 REGNO (x
), INSN_UID (insn
));
3136 fprintf (dump_file
, " with reg %d\n", REGNO (newreg
));
3138 local_copy_prop_count
++;
3145 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3146 their REG_EQUAL notes need updating to reflect that OLDREG has been
3147 replaced with NEWVAL in INSN. Return true if all substitutions could
3150 adjust_libcall_notes (rtx oldreg
, rtx newval
, rtx insn
, rtx
*libcall_sp
)
3154 while ((end
= *libcall_sp
++))
3156 rtx note
= find_reg_equal_equiv_note (end
);
3163 if (reg_set_between_p (newval
, PREV_INSN (insn
), end
))
3167 note
= find_reg_equal_equiv_note (end
);
3170 if (reg_mentioned_p (newval
, XEXP (note
, 0)))
3173 while ((end
= *libcall_sp
++));
3177 XEXP (note
, 0) = simplify_replace_rtx (XEXP (note
, 0), oldreg
, newval
);
3178 df_notes_rescan (end
);
3184 #define MAX_NESTED_LIBCALLS 9
3186 /* Do local const/copy propagation (i.e. within each basic block).
3187 If ALTER_JUMPS is true, allow propagating into jump insns, which
3188 could modify the CFG. */
3191 local_cprop_pass (bool alter_jumps
)
3195 struct reg_use
*reg_used
;
3196 rtx libcall_stack
[MAX_NESTED_LIBCALLS
+ 1], *libcall_sp
;
3197 bool changed
= false;
3199 cselib_init (false);
3200 libcall_sp
= &libcall_stack
[MAX_NESTED_LIBCALLS
];
3204 FOR_BB_INSNS (bb
, insn
)
3208 rtx note
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
);
3212 gcc_assert (libcall_sp
!= libcall_stack
);
3213 *--libcall_sp
= XEXP (note
, 0);
3215 note
= find_reg_note (insn
, REG_RETVAL
, NULL_RTX
);
3218 note
= find_reg_equal_equiv_note (insn
);
3222 note_uses (&PATTERN (insn
), local_cprop_find_used_regs
,
3225 local_cprop_find_used_regs (&XEXP (note
, 0), NULL
);
3227 for (reg_used
= ®_use_table
[0]; reg_use_count
> 0;
3228 reg_used
++, reg_use_count
--)
3230 if (do_local_cprop (reg_used
->reg_rtx
, insn
, alter_jumps
,
3237 if (INSN_DELETED_P (insn
))
3240 while (reg_use_count
);
3242 cselib_process_insn (insn
);
3245 /* Forget everything at the end of a basic block. Make sure we are
3246 not inside a libcall, they should never cross basic blocks. */
3247 cselib_clear_table ();
3248 gcc_assert (libcall_sp
== &libcall_stack
[MAX_NESTED_LIBCALLS
]);
3253 /* Global analysis may get into infinite loops for unreachable blocks. */
3254 if (changed
&& alter_jumps
)
3256 delete_unreachable_blocks ();
3257 free_reg_set_mem ();
3258 alloc_reg_set_mem (max_reg_num ());
3263 /* Forward propagate copies. This includes copies and constants. Return
3264 nonzero if a change was made. */
3267 cprop (int alter_jumps
)
3273 /* Note we start at block 1. */
3274 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3276 if (dump_file
!= NULL
)
3277 fprintf (dump_file
, "\n");
3282 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
, EXIT_BLOCK_PTR
, next_bb
)
3284 /* Reset tables used to keep track of what's still valid [since the
3285 start of the block]. */
3286 reset_opr_set_tables ();
3288 FOR_BB_INSNS (bb
, insn
)
3291 changed
|= cprop_insn (insn
, alter_jumps
);
3293 /* Keep track of everything modified by this insn. */
3294 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
3295 call mark_oprs_set if we turned the insn into a NOTE. */
3296 if (! NOTE_P (insn
))
3297 mark_oprs_set (insn
);
3301 if (dump_file
!= NULL
)
3302 fprintf (dump_file
, "\n");
3307 /* Similar to get_condition, only the resulting condition must be
3308 valid at JUMP, instead of at EARLIEST.
3310 This differs from noce_get_condition in ifcvt.c in that we prefer not to
3311 settle for the condition variable in the jump instruction being integral.
3312 We prefer to be able to record the value of a user variable, rather than
3313 the value of a temporary used in a condition. This could be solved by
3314 recording the value of *every* register scanned by canonicalize_condition,
3315 but this would require some code reorganization. */
3318 fis_get_condition (rtx jump
)
3320 return get_condition (jump
, NULL
, false, true);
3323 /* Check the comparison COND to see if we can safely form an implicit set from
3324 it. COND is either an EQ or NE comparison. */
3327 implicit_set_cond_p (const_rtx cond
)
3329 const enum machine_mode mode
= GET_MODE (XEXP (cond
, 0));
3330 const_rtx cst
= XEXP (cond
, 1);
3332 /* We can't perform this optimization if either operand might be or might
3333 contain a signed zero. */
3334 if (HONOR_SIGNED_ZEROS (mode
))
3336 /* It is sufficient to check if CST is or contains a zero. We must
3337 handle float, complex, and vector. If any subpart is a zero, then
3338 the optimization can't be performed. */
3339 /* ??? The complex and vector checks are not implemented yet. We just
3340 always return zero for them. */
3341 if (GET_CODE (cst
) == CONST_DOUBLE
)
3344 REAL_VALUE_FROM_CONST_DOUBLE (d
, cst
);
3345 if (REAL_VALUES_EQUAL (d
, dconst0
))
3352 return gcse_constant_p (cst
);
3355 /* Find the implicit sets of a function. An "implicit set" is a constraint
3356 on the value of a variable, implied by a conditional jump. For example,
3357 following "if (x == 2)", the then branch may be optimized as though the
3358 conditional performed an "explicit set", in this example, "x = 2". This
3359 function records the set patterns that are implicit at the start of each
3363 find_implicit_sets (void)
3365 basic_block bb
, dest
;
3371 /* Check for more than one successor. */
3372 if (EDGE_COUNT (bb
->succs
) > 1)
3374 cond
= fis_get_condition (BB_END (bb
));
3377 && (GET_CODE (cond
) == EQ
|| GET_CODE (cond
) == NE
)
3378 && REG_P (XEXP (cond
, 0))
3379 && REGNO (XEXP (cond
, 0)) >= FIRST_PSEUDO_REGISTER
3380 && implicit_set_cond_p (cond
))
3382 dest
= GET_CODE (cond
) == EQ
? BRANCH_EDGE (bb
)->dest
3383 : FALLTHRU_EDGE (bb
)->dest
;
3385 if (dest
&& single_pred_p (dest
)
3386 && dest
!= EXIT_BLOCK_PTR
)
3388 new = gen_rtx_SET (VOIDmode
, XEXP (cond
, 0),
3390 implicit_sets
[dest
->index
] = new;
3393 fprintf(dump_file
, "Implicit set of reg %d in ",
3394 REGNO (XEXP (cond
, 0)));
3395 fprintf(dump_file
, "basic block %d\n", dest
->index
);
3403 fprintf (dump_file
, "Found %d implicit sets\n", count
);
3406 /* Perform one copy/constant propagation pass.
3407 PASS is the pass count. If CPROP_JUMPS is true, perform constant
3408 propagation into conditional jumps. If BYPASS_JUMPS is true,
3409 perform conditional jump bypassing optimizations. */
3412 one_cprop_pass (int pass
, bool cprop_jumps
, bool bypass_jumps
)
3416 global_const_prop_count
= local_const_prop_count
= 0;
3417 global_copy_prop_count
= local_copy_prop_count
= 0;
3420 local_cprop_pass (cprop_jumps
);
3422 /* Determine implicit sets. */
3423 implicit_sets
= XCNEWVEC (rtx
, last_basic_block
);
3424 find_implicit_sets ();
3426 alloc_hash_table (max_cuid
, &set_hash_table
, 1);
3427 compute_hash_table (&set_hash_table
);
3429 /* Free implicit_sets before peak usage. */
3430 free (implicit_sets
);
3431 implicit_sets
= NULL
;
3434 dump_hash_table (dump_file
, "SET", &set_hash_table
);
3435 if (set_hash_table
.n_elems
> 0)
3437 alloc_cprop_mem (last_basic_block
, set_hash_table
.n_elems
);
3438 compute_cprop_data ();
3439 changed
= cprop (cprop_jumps
);
3441 changed
|= bypass_conditional_jumps ();
3445 free_hash_table (&set_hash_table
);
3449 fprintf (dump_file
, "CPROP of %s, pass %d: %d bytes needed, ",
3450 current_function_name (), pass
, bytes_used
);
3451 fprintf (dump_file
, "%d local const props, %d local copy props, ",
3452 local_const_prop_count
, local_copy_prop_count
);
3453 fprintf (dump_file
, "%d global const props, %d global copy props\n\n",
3454 global_const_prop_count
, global_copy_prop_count
);
3456 /* Global analysis may get into infinite loops for unreachable blocks. */
3457 if (changed
&& cprop_jumps
)
3458 delete_unreachable_blocks ();
3463 /* Bypass conditional jumps. */
3465 /* The value of last_basic_block at the beginning of the jump_bypass
3466 pass. The use of redirect_edge_and_branch_force may introduce new
3467 basic blocks, but the data flow analysis is only valid for basic
3468 block indices less than bypass_last_basic_block. */
3470 static int bypass_last_basic_block
;
3472 /* Find a set of REGNO to a constant that is available at the end of basic
3473 block BB. Returns NULL if no such set is found. Based heavily upon
3476 static struct expr
*
3477 find_bypass_set (int regno
, int bb
)
3479 struct expr
*result
= 0;
3484 struct expr
*set
= lookup_set (regno
, &set_hash_table
);
3488 if (TEST_BIT (cprop_avout
[bb
], set
->bitmap_index
))
3490 set
= next_set (regno
, set
);
3496 gcc_assert (GET_CODE (set
->expr
) == SET
);
3498 src
= SET_SRC (set
->expr
);
3499 if (gcse_constant_p (src
))
3505 regno
= REGNO (src
);
3511 /* Subroutine of bypass_block that checks whether a pseudo is killed by
3512 any of the instructions inserted on an edge. Jump bypassing places
3513 condition code setters on CFG edges using insert_insn_on_edge. This
3514 function is required to check that our data flow analysis is still
3515 valid prior to commit_edge_insertions. */
3518 reg_killed_on_edge (const_rtx reg
, const_edge e
)
3522 for (insn
= e
->insns
.r
; insn
; insn
= NEXT_INSN (insn
))
3523 if (INSN_P (insn
) && reg_set_p (reg
, insn
))
3529 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
3530 basic block BB which has more than one predecessor. If not NULL, SETCC
3531 is the first instruction of BB, which is immediately followed by JUMP_INSN
3532 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
3533 Returns nonzero if a change was made.
3535 During the jump bypassing pass, we may place copies of SETCC instructions
3536 on CFG edges. The following routine must be careful to pay attention to
3537 these inserted insns when performing its transformations. */
3540 bypass_block (basic_block bb
, rtx setcc
, rtx jump
)
3545 int may_be_loop_header
;
3549 insn
= (setcc
!= NULL
) ? setcc
: jump
;
3551 /* Determine set of register uses in INSN. */
3553 note_uses (&PATTERN (insn
), find_used_regs
, NULL
);
3554 note
= find_reg_equal_equiv_note (insn
);
3556 find_used_regs (&XEXP (note
, 0), NULL
);
3558 may_be_loop_header
= false;
3559 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3560 if (e
->flags
& EDGE_DFS_BACK
)
3562 may_be_loop_header
= true;
3567 for (ei
= ei_start (bb
->preds
); (e
= ei_safe_edge (ei
)); )
3571 if (e
->flags
& EDGE_COMPLEX
)
3577 /* We can't redirect edges from new basic blocks. */
3578 if (e
->src
->index
>= bypass_last_basic_block
)
3584 /* The irreducible loops created by redirecting of edges entering the
3585 loop from outside would decrease effectiveness of some of the following
3586 optimizations, so prevent this. */
3587 if (may_be_loop_header
3588 && !(e
->flags
& EDGE_DFS_BACK
))
3594 for (i
= 0; i
< reg_use_count
; i
++)
3596 struct reg_use
*reg_used
= ®_use_table
[i
];
3597 unsigned int regno
= REGNO (reg_used
->reg_rtx
);
3598 basic_block dest
, old_dest
;
3602 if (regno
>= max_gcse_regno
)
3605 set
= find_bypass_set (regno
, e
->src
->index
);
3610 /* Check the data flow is valid after edge insertions. */
3611 if (e
->insns
.r
&& reg_killed_on_edge (reg_used
->reg_rtx
, e
))
3614 src
= SET_SRC (pc_set (jump
));
3617 src
= simplify_replace_rtx (src
,
3618 SET_DEST (PATTERN (setcc
)),
3619 SET_SRC (PATTERN (setcc
)));
3621 new = simplify_replace_rtx (src
, reg_used
->reg_rtx
,
3622 SET_SRC (set
->expr
));
3624 /* Jump bypassing may have already placed instructions on
3625 edges of the CFG. We can't bypass an outgoing edge that
3626 has instructions associated with it, as these insns won't
3627 get executed if the incoming edge is redirected. */
3631 edest
= FALLTHRU_EDGE (bb
);
3632 dest
= edest
->insns
.r
? NULL
: edest
->dest
;
3634 else if (GET_CODE (new) == LABEL_REF
)
3636 dest
= BLOCK_FOR_INSN (XEXP (new, 0));
3637 /* Don't bypass edges containing instructions. */
3638 edest
= find_edge (bb
, dest
);
3639 if (edest
&& edest
->insns
.r
)
3645 /* Avoid unification of the edge with other edges from original
3646 branch. We would end up emitting the instruction on "both"
3649 if (dest
&& setcc
&& !CC0_P (SET_DEST (PATTERN (setcc
)))
3650 && find_edge (e
->src
, dest
))
3656 && dest
!= EXIT_BLOCK_PTR
)
3658 redirect_edge_and_branch_force (e
, dest
);
3660 /* Copy the register setter to the redirected edge.
3661 Don't copy CC0 setters, as CC0 is dead after jump. */
3664 rtx pat
= PATTERN (setcc
);
3665 if (!CC0_P (SET_DEST (pat
)))
3666 insert_insn_on_edge (copy_insn (pat
), e
);
3669 if (dump_file
!= NULL
)
3671 fprintf (dump_file
, "JUMP-BYPASS: Proved reg %d "
3672 "in jump_insn %d equals constant ",
3673 regno
, INSN_UID (jump
));
3674 print_rtl (dump_file
, SET_SRC (set
->expr
));
3675 fprintf (dump_file
, "\nBypass edge from %d->%d to %d\n",
3676 e
->src
->index
, old_dest
->index
, dest
->index
);
3689 /* Find basic blocks with more than one predecessor that only contain a
3690 single conditional jump. If the result of the comparison is known at
3691 compile-time from any incoming edge, redirect that edge to the
3692 appropriate target. Returns nonzero if a change was made.
3694 This function is now mis-named, because we also handle indirect jumps. */
3697 bypass_conditional_jumps (void)
3705 /* Note we start at block 1. */
3706 if (ENTRY_BLOCK_PTR
->next_bb
== EXIT_BLOCK_PTR
)
3709 bypass_last_basic_block
= last_basic_block
;
3710 mark_dfs_back_edges ();
3713 FOR_BB_BETWEEN (bb
, ENTRY_BLOCK_PTR
->next_bb
->next_bb
,
3714 EXIT_BLOCK_PTR
, next_bb
)
3716 /* Check for more than one predecessor. */
3717 if (!single_pred_p (bb
))
3720 FOR_BB_INSNS (bb
, insn
)
3721 if (NONJUMP_INSN_P (insn
))
3725 if (GET_CODE (PATTERN (insn
)) != SET
)
3728 dest
= SET_DEST (PATTERN (insn
));
3729 if (REG_P (dest
) || CC0_P (dest
))
3734 else if (JUMP_P (insn
))
3736 if ((any_condjump_p (insn
) || computed_jump_p (insn
))
3737 && onlyjump_p (insn
))
3738 changed
|= bypass_block (bb
, setcc
, insn
);
3741 else if (INSN_P (insn
))
3746 /* If we bypassed any register setting insns, we inserted a
3747 copy on the redirected edge. These need to be committed. */
3749 commit_edge_insertions ();
3754 /* Compute PRE+LCM working variables. */
3756 /* Local properties of expressions. */
3757 /* Nonzero for expressions that are transparent in the block. */
3758 static sbitmap
*transp
;
3760 /* Nonzero for expressions that are transparent at the end of the block.
3761 This is only zero for expressions killed by abnormal critical edge
3762 created by a calls. */
3763 static sbitmap
*transpout
;
3765 /* Nonzero for expressions that are computed (available) in the block. */
3766 static sbitmap
*comp
;
3768 /* Nonzero for expressions that are locally anticipatable in the block. */
3769 static sbitmap
*antloc
;
3771 /* Nonzero for expressions where this block is an optimal computation
3773 static sbitmap
*pre_optimal
;
3775 /* Nonzero for expressions which are redundant in a particular block. */
3776 static sbitmap
*pre_redundant
;
3778 /* Nonzero for expressions which should be inserted on a specific edge. */
3779 static sbitmap
*pre_insert_map
;
3781 /* Nonzero for expressions which should be deleted in a specific block. */
3782 static sbitmap
*pre_delete_map
;
3784 /* Contains the edge_list returned by pre_edge_lcm. */
3785 static struct edge_list
*edge_list
;
3787 /* Redundant insns. */
3788 static sbitmap pre_redundant_insns
;
3790 /* Allocate vars used for PRE analysis. */
3793 alloc_pre_mem (int n_blocks
, int n_exprs
)
3795 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3796 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3797 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3800 pre_redundant
= NULL
;
3801 pre_insert_map
= NULL
;
3802 pre_delete_map
= NULL
;
3803 ae_kill
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
3805 /* pre_insert and pre_delete are allocated later. */
3808 /* Free vars used for PRE analysis. */
3813 sbitmap_vector_free (transp
);
3814 sbitmap_vector_free (comp
);
3816 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
3819 sbitmap_vector_free (pre_optimal
);
3821 sbitmap_vector_free (pre_redundant
);
3823 sbitmap_vector_free (pre_insert_map
);
3825 sbitmap_vector_free (pre_delete_map
);
3827 transp
= comp
= NULL
;
3828 pre_optimal
= pre_redundant
= pre_insert_map
= pre_delete_map
= NULL
;
3831 /* Top level routine to do the dataflow analysis needed by PRE. */
3834 compute_pre_data (void)
3836 sbitmap trapping_expr
;
3840 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
3841 sbitmap_vector_zero (ae_kill
, last_basic_block
);
3843 /* Collect expressions which might trap. */
3844 trapping_expr
= sbitmap_alloc (expr_hash_table
.n_elems
);
3845 sbitmap_zero (trapping_expr
);
3846 for (ui
= 0; ui
< expr_hash_table
.size
; ui
++)
3849 for (e
= expr_hash_table
.table
[ui
]; e
!= NULL
; e
= e
->next_same_hash
)
3850 if (may_trap_p (e
->expr
))
3851 SET_BIT (trapping_expr
, e
->bitmap_index
);
3854 /* Compute ae_kill for each basic block using:
3864 /* If the current block is the destination of an abnormal edge, we
3865 kill all trapping expressions because we won't be able to properly
3866 place the instruction on the edge. So make them neither
3867 anticipatable nor transparent. This is fairly conservative. */
3868 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
3869 if (e
->flags
& EDGE_ABNORMAL
)
3871 sbitmap_difference (antloc
[bb
->index
], antloc
[bb
->index
], trapping_expr
);
3872 sbitmap_difference (transp
[bb
->index
], transp
[bb
->index
], trapping_expr
);
3876 sbitmap_a_or_b (ae_kill
[bb
->index
], transp
[bb
->index
], comp
[bb
->index
]);
3877 sbitmap_not (ae_kill
[bb
->index
], ae_kill
[bb
->index
]);
3880 edge_list
= pre_edge_lcm (expr_hash_table
.n_elems
, transp
, comp
, antloc
,
3881 ae_kill
, &pre_insert_map
, &pre_delete_map
);
3882 sbitmap_vector_free (antloc
);
3884 sbitmap_vector_free (ae_kill
);
3886 sbitmap_free (trapping_expr
);
3891 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
3894 VISITED is a pointer to a working buffer for tracking which BB's have
3895 been visited. It is NULL for the top-level call.
3897 We treat reaching expressions that go through blocks containing the same
3898 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3899 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3900 2 as not reaching. The intent is to improve the probability of finding
3901 only one reaching expression and to reduce register lifetimes by picking
3902 the closest such expression. */
3905 pre_expr_reaches_here_p_work (basic_block occr_bb
, struct expr
*expr
, basic_block bb
, char *visited
)
3910 FOR_EACH_EDGE (pred
, ei
, bb
->preds
)
3912 basic_block pred_bb
= pred
->src
;
3914 if (pred
->src
== ENTRY_BLOCK_PTR
3915 /* Has predecessor has already been visited? */
3916 || visited
[pred_bb
->index
])
3917 ;/* Nothing to do. */
3919 /* Does this predecessor generate this expression? */
3920 else if (TEST_BIT (comp
[pred_bb
->index
], expr
->bitmap_index
))
3922 /* Is this the occurrence we're looking for?
3923 Note that there's only one generating occurrence per block
3924 so we just need to check the block number. */
3925 if (occr_bb
== pred_bb
)
3928 visited
[pred_bb
->index
] = 1;
3930 /* Ignore this predecessor if it kills the expression. */
3931 else if (! TEST_BIT (transp
[pred_bb
->index
], expr
->bitmap_index
))
3932 visited
[pred_bb
->index
] = 1;
3934 /* Neither gen nor kill. */
3937 visited
[pred_bb
->index
] = 1;
3938 if (pre_expr_reaches_here_p_work (occr_bb
, expr
, pred_bb
, visited
))
3943 /* All paths have been checked. */
3947 /* The wrapper for pre_expr_reaches_here_work that ensures that any
3948 memory allocated for that function is returned. */
3951 pre_expr_reaches_here_p (basic_block occr_bb
, struct expr
*expr
, basic_block bb
)
3954 char *visited
= XCNEWVEC (char, last_basic_block
);
3956 rval
= pre_expr_reaches_here_p_work (occr_bb
, expr
, bb
, visited
);
3963 /* Given an expr, generate RTL which we can insert at the end of a BB,
3964 or on an edge. Set the block number of any insns generated to
3968 process_insert_insn (struct expr
*expr
)
3970 rtx reg
= expr
->reaching_reg
;
3971 rtx exp
= copy_rtx (expr
->expr
);
3976 /* If the expression is something that's an operand, like a constant,
3977 just copy it to a register. */
3978 if (general_operand (exp
, GET_MODE (reg
)))
3979 emit_move_insn (reg
, exp
);
3981 /* Otherwise, make a new insn to compute this expression and make sure the
3982 insn will be recognized (this also adds any needed CLOBBERs). Copy the
3983 expression to make sure we don't have any sharing issues. */
3986 rtx insn
= emit_insn (gen_rtx_SET (VOIDmode
, reg
, exp
));
3988 if (insn_invalid_p (insn
))
3999 /* Add EXPR to the end of basic block BB.
4001 This is used by both the PRE and code hoisting.
4003 For PRE, we want to verify that the expr is either transparent
4004 or locally anticipatable in the target block. This check makes
4005 no sense for code hoisting. */
4008 insert_insn_end_basic_block (struct expr
*expr
, basic_block bb
, int pre
)
4010 rtx insn
= BB_END (bb
);
4012 rtx reg
= expr
->reaching_reg
;
4013 int regno
= REGNO (reg
);
4016 pat
= process_insert_insn (expr
);
4017 gcc_assert (pat
&& INSN_P (pat
));
4020 while (NEXT_INSN (pat_end
) != NULL_RTX
)
4021 pat_end
= NEXT_INSN (pat_end
);
4023 /* If the last insn is a jump, insert EXPR in front [taking care to
4024 handle cc0, etc. properly]. Similarly we need to care trapping
4025 instructions in presence of non-call exceptions. */
4028 || (NONJUMP_INSN_P (insn
)
4029 && (!single_succ_p (bb
)
4030 || single_succ_edge (bb
)->flags
& EDGE_ABNORMAL
)))
4035 /* It should always be the case that we can put these instructions
4036 anywhere in the basic block with performing PRE optimizations.
4038 gcc_assert (!NONJUMP_INSN_P (insn
) || !pre
4039 || TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
4040 || TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
));
4042 /* If this is a jump table, then we can't insert stuff here. Since
4043 we know the previous real insn must be the tablejump, we insert
4044 the new instruction just before the tablejump. */
4045 if (GET_CODE (PATTERN (insn
)) == ADDR_VEC
4046 || GET_CODE (PATTERN (insn
)) == ADDR_DIFF_VEC
)
4047 insn
= prev_real_insn (insn
);
4050 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4051 if cc0 isn't set. */
4052 note
= find_reg_note (insn
, REG_CC_SETTER
, NULL_RTX
);
4054 insn
= XEXP (note
, 0);
4057 rtx maybe_cc0_setter
= prev_nonnote_insn (insn
);
4058 if (maybe_cc0_setter
4059 && INSN_P (maybe_cc0_setter
)
4060 && sets_cc0_p (PATTERN (maybe_cc0_setter
)))
4061 insn
= maybe_cc0_setter
;
4064 /* FIXME: What if something in cc0/jump uses value set in new insn? */
4065 new_insn
= emit_insn_before_noloc (pat
, insn
, bb
);
4068 /* Likewise if the last insn is a call, as will happen in the presence
4069 of exception handling. */
4070 else if (CALL_P (insn
)
4071 && (!single_succ_p (bb
)
4072 || single_succ_edge (bb
)->flags
& EDGE_ABNORMAL
))
4074 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
4075 we search backward and place the instructions before the first
4076 parameter is loaded. Do this for everyone for consistency and a
4077 presumption that we'll get better code elsewhere as well.
4079 It should always be the case that we can put these instructions
4080 anywhere in the basic block with performing PRE optimizations.
4084 || TEST_BIT (antloc
[bb
->index
], expr
->bitmap_index
)
4085 || TEST_BIT (transp
[bb
->index
], expr
->bitmap_index
));
4087 /* Since different machines initialize their parameter registers
4088 in different orders, assume nothing. Collect the set of all
4089 parameter registers. */
4090 insn
= find_first_parameter_load (insn
, BB_HEAD (bb
));
4092 /* If we found all the parameter loads, then we want to insert
4093 before the first parameter load.
4095 If we did not find all the parameter loads, then we might have
4096 stopped on the head of the block, which could be a CODE_LABEL.
4097 If we inserted before the CODE_LABEL, then we would be putting
4098 the insn in the wrong basic block. In that case, put the insn
4099 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
4100 while (LABEL_P (insn
)
4101 || NOTE_INSN_BASIC_BLOCK_P (insn
))
4102 insn
= NEXT_INSN (insn
);
4104 new_insn
= emit_insn_before_noloc (pat
, insn
, bb
);
4107 new_insn
= emit_insn_after_noloc (pat
, insn
, bb
);
4113 add_label_notes (PATTERN (pat
), new_insn
);
4114 note_stores (PATTERN (pat
), record_set_info
, pat
);
4118 pat
= NEXT_INSN (pat
);
4121 gcse_create_count
++;
4125 fprintf (dump_file
, "PRE/HOIST: end of bb %d, insn %d, ",
4126 bb
->index
, INSN_UID (new_insn
));
4127 fprintf (dump_file
, "copying expression %d to reg %d\n",
4128 expr
->bitmap_index
, regno
);
4132 /* Insert partially redundant expressions on edges in the CFG to make
4133 the expressions fully redundant. */
4136 pre_edge_insert (struct edge_list
*edge_list
, struct expr
**index_map
)
4138 int e
, i
, j
, num_edges
, set_size
, did_insert
= 0;
4141 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
4142 if it reaches any of the deleted expressions. */
4144 set_size
= pre_insert_map
[0]->size
;
4145 num_edges
= NUM_EDGES (edge_list
);
4146 inserted
= sbitmap_vector_alloc (num_edges
, expr_hash_table
.n_elems
);
4147 sbitmap_vector_zero (inserted
, num_edges
);
4149 for (e
= 0; e
< num_edges
; e
++)
4152 basic_block bb
= INDEX_EDGE_PRED_BB (edge_list
, e
);
4154 for (i
= indx
= 0; i
< set_size
; i
++, indx
+= SBITMAP_ELT_BITS
)
4156 SBITMAP_ELT_TYPE insert
= pre_insert_map
[e
]->elms
[i
];
4158 for (j
= indx
; insert
&& j
< (int) expr_hash_table
.n_elems
; j
++, insert
>>= 1)
4159 if ((insert
& 1) != 0 && index_map
[j
]->reaching_reg
!= NULL_RTX
)
4161 struct expr
*expr
= index_map
[j
];
4164 /* Now look at each deleted occurrence of this expression. */
4165 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4167 if (! occr
->deleted_p
)
4170 /* Insert this expression on this edge if it would
4171 reach the deleted occurrence in BB. */
4172 if (!TEST_BIT (inserted
[e
], j
))
4175 edge eg
= INDEX_EDGE (edge_list
, e
);
4177 /* We can't insert anything on an abnormal and
4178 critical edge, so we insert the insn at the end of
4179 the previous block. There are several alternatives
4180 detailed in Morgans book P277 (sec 10.5) for
4181 handling this situation. This one is easiest for
4184 if (eg
->flags
& EDGE_ABNORMAL
)
4185 insert_insn_end_basic_block (index_map
[j
], bb
, 0);
4188 insn
= process_insert_insn (index_map
[j
]);
4189 insert_insn_on_edge (insn
, eg
);
4194 fprintf (dump_file
, "PRE/HOIST: edge (%d,%d), ",
4196 INDEX_EDGE_SUCC_BB (edge_list
, e
)->index
);
4197 fprintf (dump_file
, "copy expression %d\n",
4198 expr
->bitmap_index
);
4201 update_ld_motion_stores (expr
);
4202 SET_BIT (inserted
[e
], j
);
4204 gcse_create_count
++;
4211 sbitmap_vector_free (inserted
);
4215 /* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
4216 Given "old_reg <- expr" (INSN), instead of adding after it
4217 reaching_reg <- old_reg
4218 it's better to do the following:
4219 reaching_reg <- expr
4220 old_reg <- reaching_reg
4221 because this way copy propagation can discover additional PRE
4222 opportunities. But if this fails, we try the old way.
4223 When "expr" is a store, i.e.
4224 given "MEM <- old_reg", instead of adding after it
4225 reaching_reg <- old_reg
4226 it's better to add it before as follows:
4227 reaching_reg <- old_reg
4228 MEM <- reaching_reg. */
4231 pre_insert_copy_insn (struct expr
*expr
, rtx insn
)
4233 rtx reg
= expr
->reaching_reg
;
4234 int regno
= REGNO (reg
);
4235 int indx
= expr
->bitmap_index
;
4236 rtx pat
= PATTERN (insn
);
4237 rtx set
, first_set
, new_insn
;
4241 /* This block matches the logic in hash_scan_insn. */
4242 switch (GET_CODE (pat
))
4249 /* Search through the parallel looking for the set whose
4250 source was the expression that we're interested in. */
4251 first_set
= NULL_RTX
;
4253 for (i
= 0; i
< XVECLEN (pat
, 0); i
++)
4255 rtx x
= XVECEXP (pat
, 0, i
);
4256 if (GET_CODE (x
) == SET
)
4258 /* If the source was a REG_EQUAL or REG_EQUIV note, we
4259 may not find an equivalent expression, but in this
4260 case the PARALLEL will have a single set. */
4261 if (first_set
== NULL_RTX
)
4263 if (expr_equiv_p (SET_SRC (x
), expr
->expr
))
4271 gcc_assert (first_set
);
4272 if (set
== NULL_RTX
)
4280 if (REG_P (SET_DEST (set
)))
4282 old_reg
= SET_DEST (set
);
4283 /* Check if we can modify the set destination in the original insn. */
4284 if (validate_change (insn
, &SET_DEST (set
), reg
, 0))
4286 new_insn
= gen_move_insn (old_reg
, reg
);
4287 new_insn
= emit_insn_after (new_insn
, insn
);
4289 /* Keep register set table up to date. */
4290 record_one_set (regno
, insn
);
4294 new_insn
= gen_move_insn (reg
, old_reg
);
4295 new_insn
= emit_insn_after (new_insn
, insn
);
4297 /* Keep register set table up to date. */
4298 record_one_set (regno
, new_insn
);
4301 else /* This is possible only in case of a store to memory. */
4303 old_reg
= SET_SRC (set
);
4304 new_insn
= gen_move_insn (reg
, old_reg
);
4306 /* Check if we can modify the set source in the original insn. */
4307 if (validate_change (insn
, &SET_SRC (set
), reg
, 0))
4308 new_insn
= emit_insn_before (new_insn
, insn
);
4310 new_insn
= emit_insn_after (new_insn
, insn
);
4312 /* Keep register set table up to date. */
4313 record_one_set (regno
, new_insn
);
4316 gcse_create_count
++;
4320 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
4321 BLOCK_NUM (insn
), INSN_UID (new_insn
), indx
,
4322 INSN_UID (insn
), regno
);
4325 /* Copy available expressions that reach the redundant expression
4326 to `reaching_reg'. */
4329 pre_insert_copies (void)
4331 unsigned int i
, added_copy
;
4336 /* For each available expression in the table, copy the result to
4337 `reaching_reg' if the expression reaches a deleted one.
4339 ??? The current algorithm is rather brute force.
4340 Need to do some profiling. */
4342 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4343 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
4345 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
4346 we don't want to insert a copy here because the expression may not
4347 really be redundant. So only insert an insn if the expression was
4348 deleted. This test also avoids further processing if the
4349 expression wasn't deleted anywhere. */
4350 if (expr
->reaching_reg
== NULL
)
4353 /* Set when we add a copy for that expression. */
4356 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4358 if (! occr
->deleted_p
)
4361 for (avail
= expr
->avail_occr
; avail
!= NULL
; avail
= avail
->next
)
4363 rtx insn
= avail
->insn
;
4365 /* No need to handle this one if handled already. */
4366 if (avail
->copied_p
)
4369 /* Don't handle this one if it's a redundant one. */
4370 if (TEST_BIT (pre_redundant_insns
, INSN_CUID (insn
)))
4373 /* Or if the expression doesn't reach the deleted one. */
4374 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail
->insn
),
4376 BLOCK_FOR_INSN (occr
->insn
)))
4381 /* Copy the result of avail to reaching_reg. */
4382 pre_insert_copy_insn (expr
, insn
);
4383 avail
->copied_p
= 1;
4388 update_ld_motion_stores (expr
);
4392 /* Emit move from SRC to DEST noting the equivalence with expression computed
4395 gcse_emit_move_after (rtx src
, rtx dest
, rtx insn
)
4398 rtx set
= single_set (insn
), set2
;
4402 /* This should never fail since we're creating a reg->reg copy
4403 we've verified to be valid. */
4405 new = emit_insn_after (gen_move_insn (dest
, src
), insn
);
4407 /* Note the equivalence for local CSE pass. */
4408 set2
= single_set (new);
4409 if (!set2
|| !rtx_equal_p (SET_DEST (set2
), dest
))
4411 if ((note
= find_reg_equal_equiv_note (insn
)))
4412 eqv
= XEXP (note
, 0);
4414 eqv
= SET_SRC (set
);
4416 set_unique_reg_note (new, REG_EQUAL
, copy_insn_1 (eqv
));
4421 /* Delete redundant computations.
4422 Deletion is done by changing the insn to copy the `reaching_reg' of
4423 the expression into the result of the SET. It is left to later passes
4424 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
4426 Returns nonzero if a change is made. */
4437 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4438 for (expr
= expr_hash_table
.table
[i
];
4440 expr
= expr
->next_same_hash
)
4442 int indx
= expr
->bitmap_index
;
4444 /* We only need to search antic_occr since we require
4447 for (occr
= expr
->antic_occr
; occr
!= NULL
; occr
= occr
->next
)
4449 rtx insn
= occr
->insn
;
4451 basic_block bb
= BLOCK_FOR_INSN (insn
);
4453 /* We only delete insns that have a single_set. */
4454 if (TEST_BIT (pre_delete_map
[bb
->index
], indx
)
4455 && (set
= single_set (insn
)) != 0
4456 && dbg_cnt (pre_insn
))
4458 /* Create a pseudo-reg to store the result of reaching
4459 expressions into. Get the mode for the new pseudo from
4460 the mode of the original destination pseudo. */
4461 if (expr
->reaching_reg
== NULL
)
4463 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
4465 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
4467 occr
->deleted_p
= 1;
4468 SET_BIT (pre_redundant_insns
, INSN_CUID (insn
));
4475 "PRE: redundant insn %d (expression %d) in ",
4476 INSN_UID (insn
), indx
);
4477 fprintf (dump_file
, "bb %d, reaching reg is %d\n",
4478 bb
->index
, REGNO (expr
->reaching_reg
));
4487 /* Perform GCSE optimizations using PRE.
4488 This is called by one_pre_gcse_pass after all the dataflow analysis
4491 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
4492 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
4493 Compiler Design and Implementation.
4495 ??? A new pseudo reg is created to hold the reaching expression. The nice
4496 thing about the classical approach is that it would try to use an existing
4497 reg. If the register can't be adequately optimized [i.e. we introduce
4498 reload problems], one could add a pass here to propagate the new register
4501 ??? We don't handle single sets in PARALLELs because we're [currently] not
4502 able to copy the rest of the parallel when we insert copies to create full
4503 redundancies from partial redundancies. However, there's no reason why we
4504 can't handle PARALLELs in the cases where there are no partial
4511 int did_insert
, changed
;
4512 struct expr
**index_map
;
4515 /* Compute a mapping from expression number (`bitmap_index') to
4516 hash table entry. */
4518 index_map
= XCNEWVEC (struct expr
*, expr_hash_table
.n_elems
);
4519 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4520 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
4521 index_map
[expr
->bitmap_index
] = expr
;
4523 /* Reset bitmap used to track which insns are redundant. */
4524 pre_redundant_insns
= sbitmap_alloc (max_cuid
);
4525 sbitmap_zero (pre_redundant_insns
);
4527 /* Delete the redundant insns first so that
4528 - we know what register to use for the new insns and for the other
4529 ones with reaching expressions
4530 - we know which insns are redundant when we go to create copies */
4532 changed
= pre_delete ();
4533 did_insert
= pre_edge_insert (edge_list
, index_map
);
4535 /* In other places with reaching expressions, copy the expression to the
4536 specially allocated pseudo-reg that reaches the redundant expr. */
4537 pre_insert_copies ();
4540 commit_edge_insertions ();
4545 sbitmap_free (pre_redundant_insns
);
4549 /* Top level routine to perform one PRE GCSE pass.
4551 Return nonzero if a change was made. */
4554 one_pre_gcse_pass (int pass
)
4558 gcse_subst_count
= 0;
4559 gcse_create_count
= 0;
4561 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
4562 add_noreturn_fake_exit_edges ();
4564 compute_ld_motion_mems ();
4566 compute_hash_table (&expr_hash_table
);
4567 trim_ld_motion_mems ();
4569 dump_hash_table (dump_file
, "Expression", &expr_hash_table
);
4571 if (expr_hash_table
.n_elems
> 0)
4573 alloc_pre_mem (last_basic_block
, expr_hash_table
.n_elems
);
4574 compute_pre_data ();
4575 changed
|= pre_gcse ();
4576 free_edge_list (edge_list
);
4581 remove_fake_exit_edges ();
4582 free_hash_table (&expr_hash_table
);
4586 fprintf (dump_file
, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
4587 current_function_name (), pass
, bytes_used
);
4588 fprintf (dump_file
, "%d substs, %d insns created\n",
4589 gcse_subst_count
, gcse_create_count
);
4595 /* If X contains any LABEL_REF's, add REG_LABEL_OPERAND notes for them
4596 to INSN. If such notes are added to an insn which references a
4597 CODE_LABEL, the LABEL_NUSES count is incremented. We have to add
4598 that note, because the following loop optimization pass requires
4601 /* ??? If there was a jump optimization pass after gcse and before loop,
4602 then we would not need to do this here, because jump would add the
4603 necessary REG_LABEL_OPERAND and REG_LABEL_TARGET notes. */
4606 add_label_notes (rtx x
, rtx insn
)
4608 enum rtx_code code
= GET_CODE (x
);
4612 if (code
== LABEL_REF
&& !LABEL_REF_NONLOCAL_P (x
))
4614 /* This code used to ignore labels that referred to dispatch tables to
4615 avoid flow generating (slightly) worse code.
4617 We no longer ignore such label references (see LABEL_REF handling in
4618 mark_jump_label for additional information). */
4620 /* There's no reason for current users to emit jump-insns with
4621 such a LABEL_REF, so we don't have to handle REG_LABEL_TARGET
4623 gcc_assert (!JUMP_P (insn
));
4625 = gen_rtx_INSN_LIST (REG_LABEL_OPERAND
, XEXP (x
, 0),
4627 if (LABEL_P (XEXP (x
, 0)))
4628 LABEL_NUSES (XEXP (x
, 0))++;
4633 for (i
= GET_RTX_LENGTH (code
) - 1, fmt
= GET_RTX_FORMAT (code
); i
>= 0; i
--)
4636 add_label_notes (XEXP (x
, i
), insn
);
4637 else if (fmt
[i
] == 'E')
4638 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
4639 add_label_notes (XVECEXP (x
, i
, j
), insn
);
4643 /* Compute transparent outgoing information for each block.
4645 An expression is transparent to an edge unless it is killed by
4646 the edge itself. This can only happen with abnormal control flow,
4647 when the edge is traversed through a call. This happens with
4648 non-local labels and exceptions.
4650 This would not be necessary if we split the edge. While this is
4651 normally impossible for abnormal critical edges, with some effort
4652 it should be possible with exception handling, since we still have
4653 control over which handler should be invoked. But due to increased
4654 EH table sizes, this may not be worthwhile. */
4657 compute_transpout (void)
4663 sbitmap_vector_ones (transpout
, last_basic_block
);
4667 /* Note that flow inserted a nop a the end of basic blocks that
4668 end in call instructions for reasons other than abnormal
4670 if (! CALL_P (BB_END (bb
)))
4673 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4674 for (expr
= expr_hash_table
.table
[i
]; expr
; expr
= expr
->next_same_hash
)
4675 if (MEM_P (expr
->expr
))
4677 if (GET_CODE (XEXP (expr
->expr
, 0)) == SYMBOL_REF
4678 && CONSTANT_POOL_ADDRESS_P (XEXP (expr
->expr
, 0)))
4681 /* ??? Optimally, we would use interprocedural alias
4682 analysis to determine if this mem is actually killed
4684 RESET_BIT (transpout
[bb
->index
], expr
->bitmap_index
);
4689 /* Code Hoisting variables and subroutines. */
4691 /* Very busy expressions. */
4692 static sbitmap
*hoist_vbein
;
4693 static sbitmap
*hoist_vbeout
;
4695 /* Hoistable expressions. */
4696 static sbitmap
*hoist_exprs
;
4698 /* ??? We could compute post dominators and run this algorithm in
4699 reverse to perform tail merging, doing so would probably be
4700 more effective than the tail merging code in jump.c.
4702 It's unclear if tail merging could be run in parallel with
4703 code hoisting. It would be nice. */
4705 /* Allocate vars used for code hoisting analysis. */
4708 alloc_code_hoist_mem (int n_blocks
, int n_exprs
)
4710 antloc
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4711 transp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4712 comp
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4714 hoist_vbein
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4715 hoist_vbeout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4716 hoist_exprs
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4717 transpout
= sbitmap_vector_alloc (n_blocks
, n_exprs
);
4720 /* Free vars used for code hoisting analysis. */
4723 free_code_hoist_mem (void)
4725 sbitmap_vector_free (antloc
);
4726 sbitmap_vector_free (transp
);
4727 sbitmap_vector_free (comp
);
4729 sbitmap_vector_free (hoist_vbein
);
4730 sbitmap_vector_free (hoist_vbeout
);
4731 sbitmap_vector_free (hoist_exprs
);
4732 sbitmap_vector_free (transpout
);
4734 free_dominance_info (CDI_DOMINATORS
);
4737 /* Compute the very busy expressions at entry/exit from each block.
4739 An expression is very busy if all paths from a given point
4740 compute the expression. */
4743 compute_code_hoist_vbeinout (void)
4745 int changed
, passes
;
4748 sbitmap_vector_zero (hoist_vbeout
, last_basic_block
);
4749 sbitmap_vector_zero (hoist_vbein
, last_basic_block
);
4758 /* We scan the blocks in the reverse order to speed up
4760 FOR_EACH_BB_REVERSE (bb
)
4762 if (bb
->next_bb
!= EXIT_BLOCK_PTR
)
4763 sbitmap_intersection_of_succs (hoist_vbeout
[bb
->index
],
4764 hoist_vbein
, bb
->index
);
4766 changed
|= sbitmap_a_or_b_and_c_cg (hoist_vbein
[bb
->index
],
4768 hoist_vbeout
[bb
->index
],
4776 fprintf (dump_file
, "hoisting vbeinout computation: %d passes\n", passes
);
4779 /* Top level routine to do the dataflow analysis needed by code hoisting. */
4782 compute_code_hoist_data (void)
4784 compute_local_properties (transp
, comp
, antloc
, &expr_hash_table
);
4785 compute_transpout ();
4786 compute_code_hoist_vbeinout ();
4787 calculate_dominance_info (CDI_DOMINATORS
);
4789 fprintf (dump_file
, "\n");
4792 /* Determine if the expression identified by EXPR_INDEX would
4793 reach BB unimpared if it was placed at the end of EXPR_BB.
4795 It's unclear exactly what Muchnick meant by "unimpared". It seems
4796 to me that the expression must either be computed or transparent in
4797 *every* block in the path(s) from EXPR_BB to BB. Any other definition
4798 would allow the expression to be hoisted out of loops, even if
4799 the expression wasn't a loop invariant.
4801 Contrast this to reachability for PRE where an expression is
4802 considered reachable if *any* path reaches instead of *all*
4806 hoist_expr_reaches_here_p (basic_block expr_bb
, int expr_index
, basic_block bb
, char *visited
)
4810 int visited_allocated_locally
= 0;
4813 if (visited
== NULL
)
4815 visited_allocated_locally
= 1;
4816 visited
= XCNEWVEC (char, last_basic_block
);
4819 FOR_EACH_EDGE (pred
, ei
, bb
->preds
)
4821 basic_block pred_bb
= pred
->src
;
4823 if (pred
->src
== ENTRY_BLOCK_PTR
)
4825 else if (pred_bb
== expr_bb
)
4827 else if (visited
[pred_bb
->index
])
4830 /* Does this predecessor generate this expression? */
4831 else if (TEST_BIT (comp
[pred_bb
->index
], expr_index
))
4833 else if (! TEST_BIT (transp
[pred_bb
->index
], expr_index
))
4839 visited
[pred_bb
->index
] = 1;
4840 if (! hoist_expr_reaches_here_p (expr_bb
, expr_index
,
4845 if (visited_allocated_locally
)
4848 return (pred
== NULL
);
4851 /* Actually perform code hoisting. */
4856 basic_block bb
, dominated
;
4857 VEC (basic_block
, heap
) *domby
;
4859 struct expr
**index_map
;
4862 sbitmap_vector_zero (hoist_exprs
, last_basic_block
);
4864 /* Compute a mapping from expression number (`bitmap_index') to
4865 hash table entry. */
4867 index_map
= XCNEWVEC (struct expr
*, expr_hash_table
.n_elems
);
4868 for (i
= 0; i
< expr_hash_table
.size
; i
++)
4869 for (expr
= expr_hash_table
.table
[i
]; expr
!= NULL
; expr
= expr
->next_same_hash
)
4870 index_map
[expr
->bitmap_index
] = expr
;
4872 /* Walk over each basic block looking for potentially hoistable
4873 expressions, nothing gets hoisted from the entry block. */
4877 int insn_inserted_p
;
4879 domby
= get_dominated_by (CDI_DOMINATORS
, bb
);
4880 /* Examine each expression that is very busy at the exit of this
4881 block. These are the potentially hoistable expressions. */
4882 for (i
= 0; i
< hoist_vbeout
[bb
->index
]->n_bits
; i
++)
4886 if (TEST_BIT (hoist_vbeout
[bb
->index
], i
)
4887 && TEST_BIT (transpout
[bb
->index
], i
))
4889 /* We've found a potentially hoistable expression, now
4890 we look at every block BB dominates to see if it
4891 computes the expression. */
4892 for (j
= 0; VEC_iterate (basic_block
, domby
, j
, dominated
); j
++)
4894 /* Ignore self dominance. */
4895 if (bb
== dominated
)
4897 /* We've found a dominated block, now see if it computes
4898 the busy expression and whether or not moving that
4899 expression to the "beginning" of that block is safe. */
4900 if (!TEST_BIT (antloc
[dominated
->index
], i
))
4903 /* Note if the expression would reach the dominated block
4904 unimpared if it was placed at the end of BB.
4906 Keep track of how many times this expression is hoistable
4907 from a dominated block into BB. */
4908 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
4912 /* If we found more than one hoistable occurrence of this
4913 expression, then note it in the bitmap of expressions to
4914 hoist. It makes no sense to hoist things which are computed
4915 in only one BB, and doing so tends to pessimize register
4916 allocation. One could increase this value to try harder
4917 to avoid any possible code expansion due to register
4918 allocation issues; however experiments have shown that
4919 the vast majority of hoistable expressions are only movable
4920 from two successors, so raising this threshold is likely
4921 to nullify any benefit we get from code hoisting. */
4924 SET_BIT (hoist_exprs
[bb
->index
], i
);
4929 /* If we found nothing to hoist, then quit now. */
4932 VEC_free (basic_block
, heap
, domby
);
4936 /* Loop over all the hoistable expressions. */
4937 for (i
= 0; i
< hoist_exprs
[bb
->index
]->n_bits
; i
++)
4939 /* We want to insert the expression into BB only once, so
4940 note when we've inserted it. */
4941 insn_inserted_p
= 0;
4943 /* These tests should be the same as the tests above. */
4944 if (TEST_BIT (hoist_exprs
[bb
->index
], i
))
4946 /* We've found a potentially hoistable expression, now
4947 we look at every block BB dominates to see if it
4948 computes the expression. */
4949 for (j
= 0; VEC_iterate (basic_block
, domby
, j
, dominated
); j
++)
4951 /* Ignore self dominance. */
4952 if (bb
== dominated
)
4955 /* We've found a dominated block, now see if it computes
4956 the busy expression and whether or not moving that
4957 expression to the "beginning" of that block is safe. */
4958 if (!TEST_BIT (antloc
[dominated
->index
], i
))
4961 /* The expression is computed in the dominated block and
4962 it would be safe to compute it at the start of the
4963 dominated block. Now we have to determine if the
4964 expression would reach the dominated block if it was
4965 placed at the end of BB. */
4966 if (hoist_expr_reaches_here_p (bb
, i
, dominated
, NULL
))
4968 struct expr
*expr
= index_map
[i
];
4969 struct occr
*occr
= expr
->antic_occr
;
4973 /* Find the right occurrence of this expression. */
4974 while (BLOCK_FOR_INSN (occr
->insn
) != dominated
&& occr
)
4979 set
= single_set (insn
);
4982 /* Create a pseudo-reg to store the result of reaching
4983 expressions into. Get the mode for the new pseudo
4984 from the mode of the original destination pseudo. */
4985 if (expr
->reaching_reg
== NULL
)
4987 = gen_reg_rtx (GET_MODE (SET_DEST (set
)));
4989 gcse_emit_move_after (expr
->reaching_reg
, SET_DEST (set
), insn
);
4991 occr
->deleted_p
= 1;
4992 if (!insn_inserted_p
)
4994 insert_insn_end_basic_block (index_map
[i
], bb
, 0);
4995 insn_inserted_p
= 1;
5001 VEC_free (basic_block
, heap
, domby
);
5007 /* Top level routine to perform one code hoisting (aka unification) pass
5009 Return nonzero if a change was made. */
5012 one_code_hoisting_pass (void)
5016 alloc_hash_table (max_cuid
, &expr_hash_table
, 0);
5017 compute_hash_table (&expr_hash_table
);
5019 dump_hash_table (dump_file
, "Code Hosting Expressions", &expr_hash_table
);
5021 if (expr_hash_table
.n_elems
> 0)
5023 alloc_code_hoist_mem (last_basic_block
, expr_hash_table
.n_elems
);
5024 compute_code_hoist_data ();
5026 free_code_hoist_mem ();
5029 free_hash_table (&expr_hash_table
);
5034 /* Here we provide the things required to do store motion towards
5035 the exit. In order for this to be effective, gcse also needed to
5036 be taught how to move a load when it is kill only by a store to itself.
5041 void foo(float scale)
5043 for (i=0; i<10; i++)
5047 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
5048 the load out since its live around the loop, and stored at the bottom
5051 The 'Load Motion' referred to and implemented in this file is
5052 an enhancement to gcse which when using edge based lcm, recognizes
5053 this situation and allows gcse to move the load out of the loop.
5055 Once gcse has hoisted the load, store motion can then push this
5056 load towards the exit, and we end up with no loads or stores of 'i'
5060 pre_ldst_expr_hash (const void *p
)
5062 int do_not_record_p
= 0;
5063 const struct ls_expr
*x
= p
;
5064 return hash_rtx (x
->pattern
, GET_MODE (x
->pattern
), &do_not_record_p
, NULL
, false);
5068 pre_ldst_expr_eq (const void *p1
, const void *p2
)
5070 const struct ls_expr
*ptr1
= p1
, *ptr2
= p2
;
5071 return expr_equiv_p (ptr1
->pattern
, ptr2
->pattern
);
5074 /* This will search the ldst list for a matching expression. If it
5075 doesn't find one, we create one and initialize it. */
5077 static struct ls_expr
*
5080 int do_not_record_p
= 0;
5081 struct ls_expr
* ptr
;
5086 hash
= hash_rtx (x
, GET_MODE (x
), &do_not_record_p
,
5087 NULL
, /*have_reg_qty=*/false);
5090 slot
= htab_find_slot_with_hash (pre_ldst_table
, &e
, hash
, INSERT
);
5092 return (struct ls_expr
*)*slot
;
5094 ptr
= XNEW (struct ls_expr
);
5096 ptr
->next
= pre_ldst_mems
;
5099 ptr
->pattern_regs
= NULL_RTX
;
5100 ptr
->loads
= NULL_RTX
;
5101 ptr
->stores
= NULL_RTX
;
5102 ptr
->reaching_reg
= NULL_RTX
;
5105 ptr
->hash_index
= hash
;
5106 pre_ldst_mems
= ptr
;
5112 /* Free up an individual ldst entry. */
5115 free_ldst_entry (struct ls_expr
* ptr
)
5117 free_INSN_LIST_list (& ptr
->loads
);
5118 free_INSN_LIST_list (& ptr
->stores
);
5123 /* Free up all memory associated with the ldst list. */
5126 free_ldst_mems (void)
5129 htab_delete (pre_ldst_table
);
5130 pre_ldst_table
= NULL
;
5132 while (pre_ldst_mems
)
5134 struct ls_expr
* tmp
= pre_ldst_mems
;
5136 pre_ldst_mems
= pre_ldst_mems
->next
;
5138 free_ldst_entry (tmp
);
5141 pre_ldst_mems
= NULL
;
5144 /* Dump debugging info about the ldst list. */
5147 print_ldst_list (FILE * file
)
5149 struct ls_expr
* ptr
;
5151 fprintf (file
, "LDST list: \n");
5153 for (ptr
= first_ls_expr (); ptr
!= NULL
; ptr
= next_ls_expr (ptr
))
5155 fprintf (file
, " Pattern (%3d): ", ptr
->index
);
5157 print_rtl (file
, ptr
->pattern
);
5159 fprintf (file
, "\n Loads : ");
5162 print_rtl (file
, ptr
->loads
);
5164 fprintf (file
, "(nil)");
5166 fprintf (file
, "\n Stores : ");
5169 print_rtl (file
, ptr
->stores
);
5171 fprintf (file
, "(nil)");
5173 fprintf (file
, "\n\n");
5176 fprintf (file
, "\n");
5179 /* Returns 1 if X is in the list of ldst only expressions. */
5181 static struct ls_expr
*
5182 find_rtx_in_ldst (rtx x
)
5186 if (!pre_ldst_table
)
5189 slot
= htab_find_slot (pre_ldst_table
, &e
, NO_INSERT
);
5190 if (!slot
|| ((struct ls_expr
*)*slot
)->invalid
)
5195 /* Assign each element of the list of mems a monotonically increasing value. */
5198 enumerate_ldsts (void)
5200 struct ls_expr
* ptr
;
5203 for (ptr
= pre_ldst_mems
; ptr
!= NULL
; ptr
= ptr
->next
)
5209 /* Return first item in the list. */
5211 static inline struct ls_expr
*
5212 first_ls_expr (void)
5214 return pre_ldst_mems
;
5217 /* Return the next item in the list after the specified one. */
5219 static inline struct ls_expr
*
5220 next_ls_expr (struct ls_expr
* ptr
)
5225 /* Load Motion for loads which only kill themselves. */
5227 /* Return true if x is a simple MEM operation, with no registers or
5228 side effects. These are the types of loads we consider for the
5229 ld_motion list, otherwise we let the usual aliasing take care of it. */
5232 simple_mem (const_rtx x
)
5237 if (MEM_VOLATILE_P (x
))
5240 if (GET_MODE (x
) == BLKmode
)
5243 /* If we are handling exceptions, we must be careful with memory references
5244 that may trap. If we are not, the behavior is undefined, so we may just
5246 if (flag_non_call_exceptions
&& may_trap_p (x
))
5249 if (side_effects_p (x
))
5252 /* Do not consider function arguments passed on stack. */
5253 if (reg_mentioned_p (stack_pointer_rtx
, x
))
5256 if (flag_float_store
&& FLOAT_MODE_P (GET_MODE (x
)))
5262 /* Make sure there isn't a buried reference in this pattern anywhere.
5263 If there is, invalidate the entry for it since we're not capable
5264 of fixing it up just yet.. We have to be sure we know about ALL
5265 loads since the aliasing code will allow all entries in the
5266 ld_motion list to not-alias itself. If we miss a load, we will get
5267 the wrong value since gcse might common it and we won't know to
5271 invalidate_any_buried_refs (rtx x
)
5275 struct ls_expr
* ptr
;
5277 /* Invalidate it in the list. */
5278 if (MEM_P (x
) && simple_mem (x
))
5280 ptr
= ldst_entry (x
);
5284 /* Recursively process the insn. */
5285 fmt
= GET_RTX_FORMAT (GET_CODE (x
));
5287 for (i
= GET_RTX_LENGTH (GET_CODE (x
)) - 1; i
>= 0; i
--)
5290 invalidate_any_buried_refs (XEXP (x
, i
));
5291 else if (fmt
[i
] == 'E')
5292 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
5293 invalidate_any_buried_refs (XVECEXP (x
, i
, j
));
5297 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
5298 being defined as MEM loads and stores to symbols, with no side effects
5299 and no registers in the expression. For a MEM destination, we also
5300 check that the insn is still valid if we replace the destination with a
5301 REG, as is done in update_ld_motion_stores. If there are any uses/defs
5302 which don't match this criteria, they are invalidated and trimmed out
5306 compute_ld_motion_mems (void)
5308 struct ls_expr
* ptr
;
5312 pre_ldst_mems
= NULL
;
5313 pre_ldst_table
= htab_create (13, pre_ldst_expr_hash
,
5314 pre_ldst_expr_eq
, NULL
);
5318 FOR_BB_INSNS (bb
, insn
)
5322 if (GET_CODE (PATTERN (insn
)) == SET
)
5324 rtx src
= SET_SRC (PATTERN (insn
));
5325 rtx dest
= SET_DEST (PATTERN (insn
));
5327 /* Check for a simple LOAD... */
5328 if (MEM_P (src
) && simple_mem (src
))
5330 ptr
= ldst_entry (src
);
5332 ptr
->loads
= alloc_INSN_LIST (insn
, ptr
->loads
);
5338 /* Make sure there isn't a buried load somewhere. */
5339 invalidate_any_buried_refs (src
);
5342 /* Check for stores. Don't worry about aliased ones, they
5343 will block any movement we might do later. We only care
5344 about this exact pattern since those are the only
5345 circumstance that we will ignore the aliasing info. */
5346 if (MEM_P (dest
) && simple_mem (dest
))
5348 ptr
= ldst_entry (dest
);
5351 && GET_CODE (src
) != ASM_OPERANDS
5352 /* Check for REG manually since want_to_gcse_p
5353 returns 0 for all REGs. */
5354 && can_assign_to_reg_p (src
))
5355 ptr
->stores
= alloc_INSN_LIST (insn
, ptr
->stores
);
5361 invalidate_any_buried_refs (PATTERN (insn
));
5367 /* Remove any references that have been either invalidated or are not in the
5368 expression list for pre gcse. */
5371 trim_ld_motion_mems (void)
5373 struct ls_expr
* * last
= & pre_ldst_mems
;
5374 struct ls_expr
* ptr
= pre_ldst_mems
;
5380 /* Delete if entry has been made invalid. */
5383 /* Delete if we cannot find this mem in the expression list. */
5384 unsigned int hash
= ptr
->hash_index
% expr_hash_table
.size
;
5386 for (expr
= expr_hash_table
.table
[hash
];
5388 expr
= expr
->next_same_hash
)
5389 if (expr_equiv_p (expr
->expr
, ptr
->pattern
))
5393 expr
= (struct expr
*) 0;
5397 /* Set the expression field if we are keeping it. */
5405 htab_remove_elt_with_hash (pre_ldst_table
, ptr
, ptr
->hash_index
);
5406 free_ldst_entry (ptr
);
5411 /* Show the world what we've found. */
5412 if (dump_file
&& pre_ldst_mems
!= NULL
)
5413 print_ldst_list (dump_file
);
5416 /* This routine will take an expression which we are replacing with
5417 a reaching register, and update any stores that are needed if
5418 that expression is in the ld_motion list. Stores are updated by
5419 copying their SRC to the reaching register, and then storing
5420 the reaching register into the store location. These keeps the
5421 correct value in the reaching register for the loads. */
5424 update_ld_motion_stores (struct expr
* expr
)
5426 struct ls_expr
* mem_ptr
;
5428 if ((mem_ptr
= find_rtx_in_ldst (expr
->expr
)))
5430 /* We can try to find just the REACHED stores, but is shouldn't
5431 matter to set the reaching reg everywhere... some might be
5432 dead and should be eliminated later. */
5434 /* We replace (set mem expr) with (set reg expr) (set mem reg)
5435 where reg is the reaching reg used in the load. We checked in
5436 compute_ld_motion_mems that we can replace (set mem expr) with
5437 (set reg expr) in that insn. */
5438 rtx list
= mem_ptr
->stores
;
5440 for ( ; list
!= NULL_RTX
; list
= XEXP (list
, 1))
5442 rtx insn
= XEXP (list
, 0);
5443 rtx pat
= PATTERN (insn
);
5444 rtx src
= SET_SRC (pat
);
5445 rtx reg
= expr
->reaching_reg
;
5448 /* If we've already copied it, continue. */
5449 if (expr
->reaching_reg
== src
)
5454 fprintf (dump_file
, "PRE: store updated with reaching reg ");
5455 print_rtl (dump_file
, expr
->reaching_reg
);
5456 fprintf (dump_file
, ":\n ");
5457 print_inline_rtx (dump_file
, insn
, 8);
5458 fprintf (dump_file
, "\n");
5461 copy
= gen_move_insn ( reg
, copy_rtx (SET_SRC (pat
)));
5462 new = emit_insn_before (copy
, insn
);
5463 record_one_set (REGNO (reg
), new);
5464 SET_SRC (pat
) = reg
;
5465 df_insn_rescan (insn
);
5467 /* un-recognize this pattern since it's probably different now. */
5468 INSN_CODE (insn
) = -1;
5469 gcse_create_count
++;
5474 /* Store motion code. */
5476 #define ANTIC_STORE_LIST(x) ((x)->loads)
5477 #define AVAIL_STORE_LIST(x) ((x)->stores)
5478 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
5480 /* This is used to communicate the target bitvector we want to use in the
5481 reg_set_info routine when called via the note_stores mechanism. */
5482 static int * regvec
;
5484 /* And current insn, for the same routine. */
5485 static rtx compute_store_table_current_insn
;
5487 /* Used in computing the reverse edge graph bit vectors. */
5488 static sbitmap
* st_antloc
;
5490 /* Global holding the number of store expressions we are dealing with. */
5491 static int num_stores
;
5493 /* Checks to set if we need to mark a register set. Called from
5497 reg_set_info (rtx dest
, const_rtx setter ATTRIBUTE_UNUSED
,
5500 sbitmap bb_reg
= data
;
5502 if (GET_CODE (dest
) == SUBREG
)
5503 dest
= SUBREG_REG (dest
);
5507 regvec
[REGNO (dest
)] = INSN_UID (compute_store_table_current_insn
);
5509 SET_BIT (bb_reg
, REGNO (dest
));
5513 /* Clear any mark that says that this insn sets dest. Called from
5517 reg_clear_last_set (rtx dest
, const_rtx setter ATTRIBUTE_UNUSED
,
5520 int *dead_vec
= data
;
5522 if (GET_CODE (dest
) == SUBREG
)
5523 dest
= SUBREG_REG (dest
);
5526 dead_vec
[REGNO (dest
)] == INSN_UID (compute_store_table_current_insn
))
5527 dead_vec
[REGNO (dest
)] = 0;
5530 /* Return zero if some of the registers in list X are killed
5531 due to set of registers in bitmap REGS_SET. */
5534 store_ops_ok (const_rtx x
, int *regs_set
)
5538 for (; x
; x
= XEXP (x
, 1))
5541 if (regs_set
[REGNO(reg
)])
5548 /* Returns a list of registers mentioned in X. */
5550 extract_mentioned_regs (rtx x
)
5552 return extract_mentioned_regs_helper (x
, NULL_RTX
);
5555 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
5558 extract_mentioned_regs_helper (rtx x
, rtx accum
)
5564 /* Repeat is used to turn tail-recursion into iteration. */
5570 code
= GET_CODE (x
);
5574 return alloc_EXPR_LIST (0, x
, accum
);
5586 /* We do not run this function with arguments having side effects. */
5606 i
= GET_RTX_LENGTH (code
) - 1;
5607 fmt
= GET_RTX_FORMAT (code
);
5613 rtx tem
= XEXP (x
, i
);
5615 /* If we are about to do the last recursive call
5616 needed at this level, change it into iteration. */
5623 accum
= extract_mentioned_regs_helper (tem
, accum
);
5625 else if (fmt
[i
] == 'E')
5629 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
5630 accum
= extract_mentioned_regs_helper (XVECEXP (x
, i
, j
), accum
);
5637 /* Determine whether INSN is MEM store pattern that we will consider moving.
5638 REGS_SET_BEFORE is bitmap of registers set before (and including) the
5639 current insn, REGS_SET_AFTER is bitmap of registers set after (and
5640 including) the insn in this basic block. We must be passing through BB from
5641 head to end, as we are using this fact to speed things up.
5643 The results are stored this way:
5645 -- the first anticipatable expression is added into ANTIC_STORE_LIST
5646 -- if the processed expression is not anticipatable, NULL_RTX is added
5647 there instead, so that we can use it as indicator that no further
5648 expression of this type may be anticipatable
5649 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
5650 consequently, all of them but this head are dead and may be deleted.
5651 -- if the expression is not available, the insn due to that it fails to be
5652 available is stored in reaching_reg.
5654 The things are complicated a bit by fact that there already may be stores
5655 to the same MEM from other blocks; also caller must take care of the
5656 necessary cleanup of the temporary markers after end of the basic block.
5660 find_moveable_store (rtx insn
, int *regs_set_before
, int *regs_set_after
)
5662 struct ls_expr
* ptr
;
5664 int check_anticipatable
, check_available
;
5665 basic_block bb
= BLOCK_FOR_INSN (insn
);
5667 set
= single_set (insn
);
5671 dest
= SET_DEST (set
);
5673 if (! MEM_P (dest
) || MEM_VOLATILE_P (dest
)
5674 || GET_MODE (dest
) == BLKmode
)
5677 if (side_effects_p (dest
))
5680 /* If we are handling exceptions, we must be careful with memory references
5681 that may trap. If we are not, the behavior is undefined, so we may just
5683 if (flag_non_call_exceptions
&& may_trap_p (dest
))
5686 /* Even if the destination cannot trap, the source may. In this case we'd
5687 need to handle updating the REG_EH_REGION note. */
5688 if (find_reg_note (insn
, REG_EH_REGION
, NULL_RTX
))
5691 /* Make sure that the SET_SRC of this store insns can be assigned to
5692 a register, or we will fail later on in replace_store_insn, which
5693 assumes that we can do this. But sometimes the target machine has
5694 oddities like MEM read-modify-write instruction. See for example
5696 if (!can_assign_to_reg_p (SET_SRC (set
)))
5699 ptr
= ldst_entry (dest
);
5700 if (!ptr
->pattern_regs
)
5701 ptr
->pattern_regs
= extract_mentioned_regs (dest
);
5703 /* Do not check for anticipatability if we either found one anticipatable
5704 store already, or tested for one and found out that it was killed. */
5705 check_anticipatable
= 0;
5706 if (!ANTIC_STORE_LIST (ptr
))
5707 check_anticipatable
= 1;
5710 tmp
= XEXP (ANTIC_STORE_LIST (ptr
), 0);
5712 && BLOCK_FOR_INSN (tmp
) != bb
)
5713 check_anticipatable
= 1;
5715 if (check_anticipatable
)
5717 if (store_killed_before (dest
, ptr
->pattern_regs
, insn
, bb
, regs_set_before
))
5721 ANTIC_STORE_LIST (ptr
) = alloc_INSN_LIST (tmp
,
5722 ANTIC_STORE_LIST (ptr
));
5725 /* It is not necessary to check whether store is available if we did
5726 it successfully before; if we failed before, do not bother to check
5727 until we reach the insn that caused us to fail. */
5728 check_available
= 0;
5729 if (!AVAIL_STORE_LIST (ptr
))
5730 check_available
= 1;
5733 tmp
= XEXP (AVAIL_STORE_LIST (ptr
), 0);
5734 if (BLOCK_FOR_INSN (tmp
) != bb
)
5735 check_available
= 1;
5737 if (check_available
)
5739 /* Check that we have already reached the insn at that the check
5740 failed last time. */
5741 if (LAST_AVAIL_CHECK_FAILURE (ptr
))
5743 for (tmp
= BB_END (bb
);
5744 tmp
!= insn
&& tmp
!= LAST_AVAIL_CHECK_FAILURE (ptr
);
5745 tmp
= PREV_INSN (tmp
))
5748 check_available
= 0;
5751 check_available
= store_killed_after (dest
, ptr
->pattern_regs
, insn
,
5753 &LAST_AVAIL_CHECK_FAILURE (ptr
));
5755 if (!check_available
)
5756 AVAIL_STORE_LIST (ptr
) = alloc_INSN_LIST (insn
, AVAIL_STORE_LIST (ptr
));
5759 /* Find available and anticipatable stores. */
5762 compute_store_table (void)
5768 int *last_set_in
, *already_set
;
5769 struct ls_expr
* ptr
, **prev_next_ptr_ptr
;
5771 max_gcse_regno
= max_reg_num ();
5773 reg_set_in_block
= sbitmap_vector_alloc (last_basic_block
,
5775 sbitmap_vector_zero (reg_set_in_block
, last_basic_block
);
5777 pre_ldst_table
= htab_create (13, pre_ldst_expr_hash
,
5778 pre_ldst_expr_eq
, NULL
);
5779 last_set_in
= XCNEWVEC (int, max_gcse_regno
);
5780 already_set
= XNEWVEC (int, max_gcse_regno
);
5782 /* Find all the stores we care about. */
5785 /* First compute the registers set in this block. */
5786 regvec
= last_set_in
;
5788 FOR_BB_INSNS (bb
, insn
)
5790 if (! INSN_P (insn
))
5795 HARD_REG_SET clobbered_regs
;
5797 get_call_invalidated_used_regs (insn
, &clobbered_regs
, true);
5798 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
5799 if (TEST_HARD_REG_BIT (clobbered_regs
, regno
))
5801 last_set_in
[regno
] = INSN_UID (insn
);
5802 SET_BIT (reg_set_in_block
[bb
->index
], regno
);
5806 pat
= PATTERN (insn
);
5807 compute_store_table_current_insn
= insn
;
5808 note_stores (pat
, reg_set_info
, reg_set_in_block
[bb
->index
]);
5811 /* Now find the stores. */
5812 memset (already_set
, 0, sizeof (int) * max_gcse_regno
);
5813 regvec
= already_set
;
5814 FOR_BB_INSNS (bb
, insn
)
5816 if (! INSN_P (insn
))
5821 HARD_REG_SET clobbered_regs
;
5823 get_call_invalidated_used_regs (insn
, &clobbered_regs
, true);
5824 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
5825 if (TEST_HARD_REG_BIT (clobbered_regs
, regno
))
5826 already_set
[regno
] = 1;
5829 pat
= PATTERN (insn
);
5830 note_stores (pat
, reg_set_info
, NULL
);
5832 /* Now that we've marked regs, look for stores. */
5833 find_moveable_store (insn
, already_set
, last_set_in
);
5835 /* Unmark regs that are no longer set. */
5836 compute_store_table_current_insn
= insn
;
5837 note_stores (pat
, reg_clear_last_set
, last_set_in
);
5840 HARD_REG_SET clobbered_regs
;
5842 get_call_invalidated_used_regs (insn
, &clobbered_regs
, true);
5843 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
5844 if (TEST_HARD_REG_BIT (clobbered_regs
, 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
6751 if (tem
|| tem2
== 2)
6753 timevar_push (TV_JUMP
);
6754 rebuild_jump_labels (get_insns ());
6756 timevar_pop (TV_JUMP
);
6761 flag_cse_skip_blocks
= save_csb
;
6762 flag_cse_follow_jumps
= save_cfj
;
6766 struct tree_opt_pass pass_gcse
=
6769 gate_handle_gcse
, /* gate */
6770 rest_of_handle_gcse
, /* execute */
6773 0, /* static_pass_number */
6774 TV_GCSE
, /* tv_id */
6775 0, /* properties_required */
6776 0, /* properties_provided */
6777 0, /* properties_destroyed */
6778 0, /* todo_flags_start */
6779 TODO_df_finish
| TODO_verify_rtl_sharing
|
6781 TODO_verify_flow
| TODO_ggc_collect
, /* todo_flags_finish */
6786 #include "gt-gcse.h"