* dbxout.c (current_file): Also wrap inside DBX_DEBUGGING_INFO ||
[official-gcc.git] / gcc / gcse.c
blob3e09f02252bb9bb7168219f14186fea4f228a5cb
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
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
11 version.
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
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
21 02111-1307, USA. */
23 /* TODO
24 - reordering of memory allocation and freeing to be more space efficient
25 - do rough calc of how many regs are needed in each block, and a rough
26 calc of how many regs are available in each class and use that to
27 throttle back the code in cases where RTX_COST is minimal.
28 - a store to the same address as a load does not kill the load if the
29 source of the store is also the destination of the load. Handling this
30 allows more load motion, particularly out of loops.
31 - ability to realloc sbitmap vectors would allow one initial computation
32 of reg_set_in_block with only subsequent additions, rather than
33 recomputing it for each pass
37 /* References searched while implementing this.
39 Compilers Principles, Techniques and Tools
40 Aho, Sethi, Ullman
41 Addison-Wesley, 1988
43 Global Optimization by Suppression of Partial Redundancies
44 E. Morel, C. Renvoise
45 communications of the acm, Vol. 22, Num. 2, Feb. 1979
47 A Portable Machine-Independent Global Optimizer - Design and Measurements
48 Frederick Chow
49 Stanford Ph.D. thesis, Dec. 1983
51 A Fast Algorithm for Code Movement Optimization
52 D.M. Dhamdhere
53 SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988
55 A Solution to a Problem with Morel and Renvoise's
56 Global Optimization by Suppression of Partial Redundancies
57 K-H Drechsler, M.P. Stadel
58 ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988
60 Practical Adaptation of the Global Optimization
61 Algorithm of Morel and Renvoise
62 D.M. Dhamdhere
63 ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991
65 Efficiently Computing Static Single Assignment Form and the Control
66 Dependence Graph
67 R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck
68 ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991
70 Lazy Code Motion
71 J. Knoop, O. Ruthing, B. Steffen
72 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
74 What's In a Region? Or Computing Control Dependence Regions in Near-Linear
75 Time for Reducible Flow Control
76 Thomas Ball
77 ACM Letters on Programming Languages and Systems,
78 Vol. 2, Num. 1-4, Mar-Dec 1993
80 An Efficient Representation for Sparse Sets
81 Preston Briggs, Linda Torczon
82 ACM Letters on Programming Languages and Systems,
83 Vol. 2, Num. 1-4, Mar-Dec 1993
85 A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion
86 K-H Drechsler, M.P. Stadel
87 ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993
89 Partial Dead Code Elimination
90 J. Knoop, O. Ruthing, B. Steffen
91 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
93 Effective Partial Redundancy Elimination
94 P. Briggs, K.D. Cooper
95 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
97 The Program Structure Tree: Computing Control Regions in Linear Time
98 R. Johnson, D. Pearson, K. Pingali
99 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
101 Optimal Code Motion: Theory and Practice
102 J. Knoop, O. Ruthing, B. Steffen
103 ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994
105 The power of assignment motion
106 J. Knoop, O. Ruthing, B. Steffen
107 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
109 Global code motion / global value numbering
110 C. Click
111 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
113 Value Driven Redundancy Elimination
114 L.T. Simpson
115 Rice University Ph.D. thesis, Apr. 1996
117 Value Numbering
118 L.T. Simpson
119 Massively Scalar Compiler Project, Rice University, Sep. 1996
121 High Performance Compilers for Parallel Computing
122 Michael Wolfe
123 Addison-Wesley, 1996
125 Advanced Compiler Design and Implementation
126 Steven Muchnick
127 Morgan Kaufmann, 1997
129 Building an Optimizing Compiler
130 Robert Morgan
131 Digital Press, 1998
133 People wishing to speed up the code here should read:
134 Elimination Algorithms for Data Flow Analysis
135 B.G. Ryder, M.C. Paull
136 ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986
138 How to Analyze Large Programs Efficiently and Informatively
139 D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck
140 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
142 People wishing to do something different can find various possibilities
143 in the above papers and elsewhere.
146 #include "config.h"
147 #include "system.h"
148 #include "coretypes.h"
149 #include "tm.h"
150 #include "toplev.h"
152 #include "rtl.h"
153 #include "tm_p.h"
154 #include "regs.h"
155 #include "hard-reg-set.h"
156 #include "flags.h"
157 #include "real.h"
158 #include "insn-config.h"
159 #include "recog.h"
160 #include "basic-block.h"
161 #include "output.h"
162 #include "function.h"
163 #include "expr.h"
164 #include "except.h"
165 #include "ggc.h"
166 #include "params.h"
167 #include "cselib.h"
168 #include "intl.h"
169 #include "obstack.h"
171 /* Propagate flow information through back edges and thus enable PRE's
172 moving loop invariant calculations out of loops.
174 Originally this tended to create worse overall code, but several
175 improvements during the development of PRE seem to have made following
176 back edges generally a win.
178 Note much of the loop invariant code motion done here would normally
179 be done by loop.c, which has more heuristics for when to move invariants
180 out of loops. At some point we might need to move some of those
181 heuristics into gcse.c. */
183 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
184 are a superset of those done by GCSE.
186 We perform the following steps:
188 1) Compute basic block information.
190 2) Compute table of places where registers are set.
192 3) Perform copy/constant propagation.
194 4) Perform global cse.
196 5) Perform another pass of copy/constant propagation.
198 Two passes of copy/constant propagation are done because the first one
199 enables more GCSE and the second one helps to clean up the copies that
200 GCSE creates. This is needed more for PRE than for Classic because Classic
201 GCSE will try to use an existing register containing the common
202 subexpression rather than create a new one. This is harder to do for PRE
203 because of the code motion (which Classic GCSE doesn't do).
205 Expressions we are interested in GCSE-ing are of the form
206 (set (pseudo-reg) (expression)).
207 Function want_to_gcse_p says what these are.
209 PRE handles moving invariant expressions out of loops (by treating them as
210 partially redundant).
212 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
213 assignment) based GVN (global value numbering). L. T. Simpson's paper
214 (Rice University) on value numbering is a useful reference for this.
216 **********************
218 We used to support multiple passes but there are diminishing returns in
219 doing so. The first pass usually makes 90% of the changes that are doable.
220 A second pass can make a few more changes made possible by the first pass.
221 Experiments show any further passes don't make enough changes to justify
222 the expense.
224 A study of spec92 using an unlimited number of passes:
225 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
226 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
227 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
229 It was found doing copy propagation between each pass enables further
230 substitutions.
232 PRE is quite expensive in complicated functions because the DFA can take
233 awhile to converge. Hence we only perform one pass. The parameter max-gcse-passes can
234 be modified if one wants to experiment.
236 **********************
238 The steps for PRE are:
240 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
242 2) Perform the data flow analysis for PRE.
244 3) Delete the redundant instructions
246 4) Insert the required copies [if any] that make the partially
247 redundant instructions fully redundant.
249 5) For other reaching expressions, insert an instruction to copy the value
250 to a newly created pseudo that will reach the redundant instruction.
252 The deletion is done first so that when we do insertions we
253 know which pseudo reg to use.
255 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
256 argue it is not. The number of iterations for the algorithm to converge
257 is typically 2-4 so I don't view it as that expensive (relatively speaking).
259 PRE GCSE depends heavily on the second CSE pass to clean up the copies
260 we create. To make an expression reach the place where it's redundant,
261 the result of the expression is copied to a new register, and the redundant
262 expression is deleted by replacing it with this new register. Classic GCSE
263 doesn't have this problem as much as it computes the reaching defs of
264 each register in each block and thus can try to use an existing register.
266 **********************
268 A fair bit of simplicity is created by creating small functions for simple
269 tasks, even when the function is only called in one place. This may
270 measurably slow things down [or may not] by creating more function call
271 overhead than is necessary. The source is laid out so that it's trivial
272 to make the affected functions inline so that one can measure what speed
273 up, if any, can be achieved, and maybe later when things settle things can
274 be rearranged.
276 Help stamp out big monolithic functions! */
278 /* GCSE global vars. */
280 /* -dG dump file. */
281 static FILE *gcse_file;
283 /* Note whether or not we should run jump optimization after gcse. We
284 want to do this for two cases.
286 * If we changed any jumps via cprop.
288 * If we added any labels via edge splitting. */
290 static int run_jump_opt_after_gcse;
292 /* Bitmaps are normally not included in debugging dumps.
293 However it's useful to be able to print them from GDB.
294 We could create special functions for this, but it's simpler to
295 just allow passing stderr to the dump_foo fns. Since stderr can
296 be a macro, we store a copy here. */
297 static FILE *debug_stderr;
299 /* An obstack for our working variables. */
300 static struct obstack gcse_obstack;
302 struct reg_use {rtx reg_rtx; };
304 /* Hash table of expressions. */
306 struct expr
308 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
309 rtx expr;
310 /* Index in the available expression bitmaps. */
311 int bitmap_index;
312 /* Next entry with the same hash. */
313 struct expr *next_same_hash;
314 /* List of anticipatable occurrences in basic blocks in the function.
315 An "anticipatable occurrence" is one that is the first occurrence in the
316 basic block, the operands are not modified in the basic block prior
317 to the occurrence and the output is not used between the start of
318 the block and the occurrence. */
319 struct occr *antic_occr;
320 /* List of available occurrence in basic blocks in the function.
321 An "available occurrence" is one that is the last occurrence in the
322 basic block and the operands are not modified by following statements in
323 the basic block [including this insn]. */
324 struct occr *avail_occr;
325 /* Non-null if the computation is PRE redundant.
326 The value is the newly created pseudo-reg to record a copy of the
327 expression in all the places that reach the redundant copy. */
328 rtx reaching_reg;
331 /* Occurrence of an expression.
332 There is one per basic block. If a pattern appears more than once the
333 last appearance is used [or first for anticipatable expressions]. */
335 struct occr
337 /* Next occurrence of this expression. */
338 struct occr *next;
339 /* The insn that computes the expression. */
340 rtx insn;
341 /* Nonzero if this [anticipatable] occurrence has been deleted. */
342 char deleted_p;
343 /* Nonzero if this [available] occurrence has been copied to
344 reaching_reg. */
345 /* ??? This is mutually exclusive with deleted_p, so they could share
346 the same byte. */
347 char copied_p;
350 /* Expression and copy propagation hash tables.
351 Each hash table is an array of buckets.
352 ??? It is known that if it were an array of entries, structure elements
353 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
354 not clear whether in the final analysis a sufficient amount of memory would
355 be saved as the size of the available expression bitmaps would be larger
356 [one could build a mapping table without holes afterwards though].
357 Someday I'll perform the computation and figure it out. */
359 struct hash_table
361 /* The table itself.
362 This is an array of `expr_hash_table_size' elements. */
363 struct expr **table;
365 /* Size of the hash table, in elements. */
366 unsigned int size;
368 /* Number of hash table elements. */
369 unsigned int n_elems;
371 /* Whether the table is expression of copy propagation one. */
372 int set_p;
375 /* Expression hash table. */
376 static struct hash_table expr_hash_table;
378 /* Copy propagation hash table. */
379 static struct hash_table set_hash_table;
381 /* Mapping of uids to cuids.
382 Only real insns get cuids. */
383 static int *uid_cuid;
385 /* Highest UID in UID_CUID. */
386 static int max_uid;
388 /* Get the cuid of an insn. */
389 #ifdef ENABLE_CHECKING
390 #define INSN_CUID(INSN) (INSN_UID (INSN) > max_uid ? (abort (), 0) : uid_cuid[INSN_UID (INSN)])
391 #else
392 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
393 #endif
395 /* Number of cuids. */
396 static int max_cuid;
398 /* Mapping of cuids to insns. */
399 static rtx *cuid_insn;
401 /* Get insn from cuid. */
402 #define CUID_INSN(CUID) (cuid_insn[CUID])
404 /* Maximum register number in function prior to doing gcse + 1.
405 Registers created during this pass have regno >= max_gcse_regno.
406 This is named with "gcse" to not collide with global of same name. */
407 static unsigned int max_gcse_regno;
409 /* Table of registers that are modified.
411 For each register, each element is a list of places where the pseudo-reg
412 is set.
414 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
415 requires knowledge of which blocks kill which regs [and thus could use
416 a bitmap instead of the lists `reg_set_table' uses].
418 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
419 num-regs) [however perhaps it may be useful to keep the data as is]. One
420 advantage of recording things this way is that `reg_set_table' is fairly
421 sparse with respect to pseudo regs but for hard regs could be fairly dense
422 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
423 up functions like compute_transp since in the case of pseudo-regs we only
424 need to iterate over the number of times a pseudo-reg is set, not over the
425 number of basic blocks [clearly there is a bit of a slow down in the cases
426 where a pseudo is set more than once in a block, however it is believed
427 that the net effect is to speed things up]. This isn't done for hard-regs
428 because recording call-clobbered hard-regs in `reg_set_table' at each
429 function call can consume a fair bit of memory, and iterating over
430 hard-regs stored this way in compute_transp will be more expensive. */
432 typedef struct reg_set
434 /* The next setting of this register. */
435 struct reg_set *next;
436 /* The insn where it was set. */
437 rtx insn;
438 } reg_set;
440 static reg_set **reg_set_table;
442 /* Size of `reg_set_table'.
443 The table starts out at max_gcse_regno + slop, and is enlarged as
444 necessary. */
445 static int reg_set_table_size;
447 /* Amount to grow `reg_set_table' by when it's full. */
448 #define REG_SET_TABLE_SLOP 100
450 /* This is a list of expressions which are MEMs and will be used by load
451 or store motion.
452 Load motion tracks MEMs which aren't killed by
453 anything except itself. (ie, loads and stores to a single location).
454 We can then allow movement of these MEM refs with a little special
455 allowance. (all stores copy the same value to the reaching reg used
456 for the loads). This means all values used to store into memory must have
457 no side effects so we can re-issue the setter value.
458 Store Motion uses this structure as an expression table to track stores
459 which look interesting, and might be moveable towards the exit block. */
461 struct ls_expr
463 struct expr * expr; /* Gcse expression reference for LM. */
464 rtx pattern; /* Pattern of this mem. */
465 rtx pattern_regs; /* List of registers mentioned by the mem. */
466 rtx loads; /* INSN list of loads seen. */
467 rtx stores; /* INSN list of stores seen. */
468 struct ls_expr * next; /* Next in the list. */
469 int invalid; /* Invalid for some reason. */
470 int index; /* If it maps to a bitmap index. */
471 int hash_index; /* Index when in a hash table. */
472 rtx reaching_reg; /* Register to use when re-writing. */
475 /* Array of implicit set patterns indexed by basic block index. */
476 static rtx *implicit_sets;
478 /* Head of the list of load/store memory refs. */
479 static struct ls_expr * pre_ldst_mems = NULL;
481 /* Bitmap containing one bit for each register in the program.
482 Used when performing GCSE to track which registers have been set since
483 the start of the basic block. */
484 static regset reg_set_bitmap;
486 /* For each block, a bitmap of registers set in the block.
487 This is used by expr_killed_p and compute_transp.
488 It is computed during hash table computation and not by compute_sets
489 as it includes registers added since the last pass (or between cprop and
490 gcse) and it's currently not easy to realloc sbitmap vectors. */
491 static sbitmap *reg_set_in_block;
493 /* Array, indexed by basic block number for a list of insns which modify
494 memory within that block. */
495 static rtx * modify_mem_list;
496 bitmap modify_mem_list_set;
498 /* This array parallels modify_mem_list, but is kept canonicalized. */
499 static rtx * canon_modify_mem_list;
500 bitmap canon_modify_mem_list_set;
501 /* Various variables for statistics gathering. */
503 /* Memory used in a pass.
504 This isn't intended to be absolutely precise. Its intent is only
505 to keep an eye on memory usage. */
506 static int bytes_used;
508 /* GCSE substitutions made. */
509 static int gcse_subst_count;
510 /* Number of copy instructions created. */
511 static int gcse_create_count;
512 /* Number of constants propagated. */
513 static int const_prop_count;
514 /* Number of copys propagated. */
515 static int copy_prop_count;
517 /* These variables are used by classic GCSE.
518 Normally they'd be defined a bit later, but `rd_gen' needs to
519 be declared sooner. */
521 /* Each block has a bitmap of each type.
522 The length of each blocks bitmap is:
524 max_cuid - for reaching definitions
525 n_exprs - for available expressions
527 Thus we view the bitmaps as 2 dimensional arrays. i.e.
528 rd_kill[block_num][cuid_num]
529 ae_kill[block_num][expr_num] */
531 /* For reaching defs */
532 static sbitmap *rd_kill, *rd_gen, *reaching_defs, *rd_out;
534 /* for available exprs */
535 static sbitmap *ae_kill, *ae_gen, *ae_in, *ae_out;
537 /* Objects of this type are passed around by the null-pointer check
538 removal routines. */
539 struct null_pointer_info
541 /* The basic block being processed. */
542 basic_block current_block;
543 /* The first register to be handled in this pass. */
544 unsigned int min_reg;
545 /* One greater than the last register to be handled in this pass. */
546 unsigned int max_reg;
547 sbitmap *nonnull_local;
548 sbitmap *nonnull_killed;
551 static void compute_can_copy (void);
552 static void *gmalloc (size_t) ATTRIBUTE_MALLOC;
553 static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC;
554 static void *grealloc (void *, size_t);
555 static void *gcse_alloc (unsigned long);
556 static void alloc_gcse_mem (rtx);
557 static void free_gcse_mem (void);
558 static void alloc_reg_set_mem (int);
559 static void free_reg_set_mem (void);
560 static int get_bitmap_width (int, int, int);
561 static void record_one_set (int, rtx);
562 static void replace_one_set (int, rtx, rtx);
563 static void record_set_info (rtx, rtx, void *);
564 static void compute_sets (rtx);
565 static void hash_scan_insn (rtx, struct hash_table *, int);
566 static void hash_scan_set (rtx, rtx, struct hash_table *);
567 static void hash_scan_clobber (rtx, rtx, struct hash_table *);
568 static void hash_scan_call (rtx, rtx, struct hash_table *);
569 static int want_to_gcse_p (rtx);
570 static bool gcse_constant_p (rtx);
571 static int oprs_unchanged_p (rtx, rtx, int);
572 static int oprs_anticipatable_p (rtx, rtx);
573 static int oprs_available_p (rtx, rtx);
574 static void insert_expr_in_table (rtx, enum machine_mode, rtx, int, int,
575 struct hash_table *);
576 static void insert_set_in_table (rtx, rtx, struct hash_table *);
577 static unsigned int hash_expr (rtx, enum machine_mode, int *, int);
578 static unsigned int hash_expr_1 (rtx, enum machine_mode, int *);
579 static unsigned int hash_string_1 (const char *);
580 static unsigned int hash_set (int, int);
581 static int expr_equiv_p (rtx, rtx);
582 static void record_last_reg_set_info (rtx, int);
583 static void record_last_mem_set_info (rtx);
584 static void record_last_set_info (rtx, rtx, void *);
585 static void compute_hash_table (struct hash_table *);
586 static void alloc_hash_table (int, struct hash_table *, int);
587 static void free_hash_table (struct hash_table *);
588 static void compute_hash_table_work (struct hash_table *);
589 static void dump_hash_table (FILE *, const char *, struct hash_table *);
590 static struct expr *lookup_expr (rtx, struct hash_table *);
591 static struct expr *lookup_set (unsigned int, struct hash_table *);
592 static struct expr *next_set (unsigned int, struct expr *);
593 static void reset_opr_set_tables (void);
594 static int oprs_not_set_p (rtx, rtx);
595 static void mark_call (rtx);
596 static void mark_set (rtx, rtx);
597 static void mark_clobber (rtx, rtx);
598 static void mark_oprs_set (rtx);
599 static void alloc_cprop_mem (int, int);
600 static void free_cprop_mem (void);
601 static void compute_transp (rtx, int, sbitmap *, int);
602 static void compute_transpout (void);
603 static void compute_local_properties (sbitmap *, sbitmap *, sbitmap *,
604 struct hash_table *);
605 static void compute_cprop_data (void);
606 static void find_used_regs (rtx *, void *);
607 static int try_replace_reg (rtx, rtx, rtx);
608 static struct expr *find_avail_set (int, rtx);
609 static int cprop_jump (basic_block, rtx, rtx, rtx, rtx);
610 static void mems_conflict_for_gcse_p (rtx, rtx, void *);
611 static int load_killed_in_block_p (basic_block, int, rtx, int);
612 static void canon_list_insert (rtx, rtx, void *);
613 static int cprop_insn (rtx, int);
614 static int cprop (int);
615 static void find_implicit_sets (void);
616 static int one_cprop_pass (int, int, int);
617 static bool constprop_register (rtx, rtx, rtx, int);
618 static struct expr *find_bypass_set (int, int);
619 static bool reg_killed_on_edge (rtx, edge);
620 static int bypass_block (basic_block, rtx, rtx);
621 static int bypass_conditional_jumps (void);
622 static void alloc_pre_mem (int, int);
623 static void free_pre_mem (void);
624 static void compute_pre_data (void);
625 static int pre_expr_reaches_here_p (basic_block, struct expr *,
626 basic_block);
627 static void insert_insn_end_bb (struct expr *, basic_block, int);
628 static void pre_insert_copy_insn (struct expr *, rtx);
629 static void pre_insert_copies (void);
630 static int pre_delete (void);
631 static int pre_gcse (void);
632 static int one_pre_gcse_pass (int);
633 static void add_label_notes (rtx, rtx);
634 static void alloc_code_hoist_mem (int, int);
635 static void free_code_hoist_mem (void);
636 static void compute_code_hoist_vbeinout (void);
637 static void compute_code_hoist_data (void);
638 static int hoist_expr_reaches_here_p (basic_block, int, basic_block, char *);
639 static void hoist_code (void);
640 static int one_code_hoisting_pass (void);
641 static void alloc_rd_mem (int, int);
642 static void free_rd_mem (void);
643 static void handle_rd_kill_set (rtx, int, basic_block);
644 static void compute_kill_rd (void);
645 static void compute_rd (void);
646 static void alloc_avail_expr_mem (int, int);
647 static void free_avail_expr_mem (void);
648 static void compute_ae_gen (struct hash_table *);
649 static int expr_killed_p (rtx, basic_block);
650 static void compute_ae_kill (sbitmap *, sbitmap *, struct hash_table *);
651 static int expr_reaches_here_p (struct occr *, struct expr *, basic_block,
652 int);
653 static rtx computing_insn (struct expr *, rtx);
654 static int def_reaches_here_p (rtx, rtx);
655 static int can_disregard_other_sets (struct reg_set **, rtx, int);
656 static int handle_avail_expr (rtx, struct expr *);
657 static int classic_gcse (void);
658 static int one_classic_gcse_pass (int);
659 static void invalidate_nonnull_info (rtx, rtx, void *);
660 static int delete_null_pointer_checks_1 (unsigned int *, sbitmap *, sbitmap *,
661 struct null_pointer_info *);
662 static rtx process_insert_insn (struct expr *);
663 static int pre_edge_insert (struct edge_list *, struct expr **);
664 static int expr_reaches_here_p_work (struct occr *, struct expr *,
665 basic_block, int, char *);
666 static int pre_expr_reaches_here_p_work (basic_block, struct expr *,
667 basic_block, char *);
668 static struct ls_expr * ldst_entry (rtx);
669 static void free_ldst_entry (struct ls_expr *);
670 static void free_ldst_mems (void);
671 static void print_ldst_list (FILE *);
672 static struct ls_expr * find_rtx_in_ldst (rtx);
673 static int enumerate_ldsts (void);
674 static inline struct ls_expr * first_ls_expr (void);
675 static inline struct ls_expr * next_ls_expr (struct ls_expr *);
676 static int simple_mem (rtx);
677 static void invalidate_any_buried_refs (rtx);
678 static void compute_ld_motion_mems (void);
679 static void trim_ld_motion_mems (void);
680 static void update_ld_motion_stores (struct expr *);
681 static void reg_set_info (rtx, rtx, void *);
682 static bool store_ops_ok (rtx, int *);
683 static rtx extract_mentioned_regs (rtx);
684 static rtx extract_mentioned_regs_helper (rtx, rtx);
685 static void find_moveable_store (rtx, int *, int *);
686 static int compute_store_table (void);
687 static bool load_kills_store (rtx, rtx, int);
688 static bool find_loads (rtx, rtx, int);
689 static bool store_killed_in_insn (rtx, rtx, rtx, int);
690 static bool store_killed_after (rtx, rtx, rtx, basic_block, int *, rtx *);
691 static bool store_killed_before (rtx, rtx, rtx, basic_block, int *);
692 static void build_store_vectors (void);
693 static void insert_insn_start_bb (rtx, basic_block);
694 static int insert_store (struct ls_expr *, edge);
695 static void remove_reachable_equiv_notes (basic_block, struct ls_expr *);
696 static void replace_store_insn (rtx, rtx, basic_block, struct ls_expr *);
697 static void delete_store (struct ls_expr *, basic_block);
698 static void free_store_memory (void);
699 static void store_motion (void);
700 static void free_insn_expr_list_list (rtx *);
701 static void clear_modify_mem_tables (void);
702 static void free_modify_mem_tables (void);
703 static rtx gcse_emit_move_after (rtx, rtx, rtx);
704 static void local_cprop_find_used_regs (rtx *, void *);
705 static bool do_local_cprop (rtx, rtx, int, rtx*);
706 static bool adjust_libcall_notes (rtx, rtx, rtx, rtx*);
707 static void local_cprop_pass (int);
708 static bool is_too_expensive (const char *);
711 /* Entry point for global common subexpression elimination.
712 F is the first instruction in the function. */
715 gcse_main (rtx f, FILE *file)
717 int changed, pass;
718 /* Bytes used at start of pass. */
719 int initial_bytes_used;
720 /* Maximum number of bytes used by a pass. */
721 int max_pass_bytes;
722 /* Point to release obstack data from for each pass. */
723 char *gcse_obstack_bottom;
725 /* We do not construct an accurate cfg in functions which call
726 setjmp, so just punt to be safe. */
727 if (current_function_calls_setjmp)
728 return 0;
730 /* Assume that we do not need to run jump optimizations after gcse. */
731 run_jump_opt_after_gcse = 0;
733 /* For calling dump_foo fns from gdb. */
734 debug_stderr = stderr;
735 gcse_file = file;
737 /* Identify the basic block information for this function, including
738 successors and predecessors. */
739 max_gcse_regno = max_reg_num ();
741 if (file)
742 dump_flow_info (file);
744 /* Return if there's nothing to do, or it is too expensive. */
745 if (n_basic_blocks <= 1 || is_too_expensive (_("GCSE disabled")))
746 return 0;
748 gcc_obstack_init (&gcse_obstack);
749 bytes_used = 0;
751 /* We need alias. */
752 init_alias_analysis ();
753 /* Record where pseudo-registers are set. This data is kept accurate
754 during each pass. ??? We could also record hard-reg information here
755 [since it's unchanging], however it is currently done during hash table
756 computation.
758 It may be tempting to compute MEM set information here too, but MEM sets
759 will be subject to code motion one day and thus we need to compute
760 information about memory sets when we build the hash tables. */
762 alloc_reg_set_mem (max_gcse_regno);
763 compute_sets (f);
765 pass = 0;
766 initial_bytes_used = bytes_used;
767 max_pass_bytes = 0;
768 gcse_obstack_bottom = gcse_alloc (1);
769 changed = 1;
770 while (changed && pass < MAX_GCSE_PASSES)
772 changed = 0;
773 if (file)
774 fprintf (file, "GCSE pass %d\n\n", pass + 1);
776 /* Initialize bytes_used to the space for the pred/succ lists,
777 and the reg_set_table data. */
778 bytes_used = initial_bytes_used;
780 /* Each pass may create new registers, so recalculate each time. */
781 max_gcse_regno = max_reg_num ();
783 alloc_gcse_mem (f);
785 /* Don't allow constant propagation to modify jumps
786 during this pass. */
787 changed = one_cprop_pass (pass + 1, 0, 0);
789 if (optimize_size)
790 changed |= one_classic_gcse_pass (pass + 1);
791 else
793 changed |= one_pre_gcse_pass (pass + 1);
794 /* We may have just created new basic blocks. Release and
795 recompute various things which are sized on the number of
796 basic blocks. */
797 if (changed)
799 free_modify_mem_tables ();
800 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
801 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
803 free_reg_set_mem ();
804 alloc_reg_set_mem (max_reg_num ());
805 compute_sets (f);
806 run_jump_opt_after_gcse = 1;
809 if (max_pass_bytes < bytes_used)
810 max_pass_bytes = bytes_used;
812 /* Free up memory, then reallocate for code hoisting. We can
813 not re-use the existing allocated memory because the tables
814 will not have info for the insns or registers created by
815 partial redundancy elimination. */
816 free_gcse_mem ();
818 /* It does not make sense to run code hoisting unless we optimizing
819 for code size -- it rarely makes programs faster, and can make
820 them bigger if we did partial redundancy elimination (when optimizing
821 for space, we use a classic gcse algorithm instead of partial
822 redundancy algorithms). */
823 if (optimize_size)
825 max_gcse_regno = max_reg_num ();
826 alloc_gcse_mem (f);
827 changed |= one_code_hoisting_pass ();
828 free_gcse_mem ();
830 if (max_pass_bytes < bytes_used)
831 max_pass_bytes = bytes_used;
834 if (file)
836 fprintf (file, "\n");
837 fflush (file);
840 obstack_free (&gcse_obstack, gcse_obstack_bottom);
841 pass++;
844 /* Do one last pass of copy propagation, including cprop into
845 conditional jumps. */
847 max_gcse_regno = max_reg_num ();
848 alloc_gcse_mem (f);
849 /* This time, go ahead and allow cprop to alter jumps. */
850 one_cprop_pass (pass + 1, 1, 0);
851 free_gcse_mem ();
853 if (file)
855 fprintf (file, "GCSE of %s: %d basic blocks, ",
856 current_function_name, n_basic_blocks);
857 fprintf (file, "%d pass%s, %d bytes\n\n",
858 pass, pass > 1 ? "es" : "", max_pass_bytes);
861 obstack_free (&gcse_obstack, NULL);
862 free_reg_set_mem ();
863 /* We are finished with alias. */
864 end_alias_analysis ();
865 allocate_reg_info (max_reg_num (), FALSE, FALSE);
867 if (!optimize_size && flag_gcse_sm)
868 store_motion ();
870 /* Record where pseudo-registers are set. */
871 return run_jump_opt_after_gcse;
874 /* Misc. utilities. */
876 /* Nonzero for each mode that supports (set (reg) (reg)).
877 This is trivially true for integer and floating point values.
878 It may or may not be true for condition codes. */
879 static char can_copy[(int) NUM_MACHINE_MODES];
881 /* Compute which modes support reg/reg copy operations. */
883 static void
884 compute_can_copy (void)
886 int i;
887 #ifndef AVOID_CCMODE_COPIES
888 rtx reg, insn;
889 #endif
890 memset (can_copy, 0, NUM_MACHINE_MODES);
892 start_sequence ();
893 for (i = 0; i < NUM_MACHINE_MODES; i++)
894 if (GET_MODE_CLASS (i) == MODE_CC)
896 #ifdef AVOID_CCMODE_COPIES
897 can_copy[i] = 0;
898 #else
899 reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1);
900 insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
901 if (recog (PATTERN (insn), insn, NULL) >= 0)
902 can_copy[i] = 1;
903 #endif
905 else
906 can_copy[i] = 1;
908 end_sequence ();
911 /* Returns whether the mode supports reg/reg copy operations. */
913 bool
914 can_copy_p (enum machine_mode mode)
916 static bool can_copy_init_p = false;
918 if (! can_copy_init_p)
920 compute_can_copy ();
921 can_copy_init_p = true;
924 return can_copy[mode] != 0;
927 /* Cover function to xmalloc to record bytes allocated. */
929 static void *
930 gmalloc (size_t size)
932 bytes_used += size;
933 return xmalloc (size);
936 /* Cover function to xcalloc to record bytes allocated. */
938 static void *
939 gcalloc (size_t nelem, size_t elsize)
941 bytes_used += nelem * elsize;
942 return xcalloc (nelem, elsize);
945 /* Cover function to xrealloc.
946 We don't record the additional size since we don't know it.
947 It won't affect memory usage stats much anyway. */
949 static void *
950 grealloc (void *ptr, size_t size)
952 return xrealloc (ptr, size);
955 /* Cover function to obstack_alloc. */
957 static void *
958 gcse_alloc (unsigned long size)
960 bytes_used += size;
961 return obstack_alloc (&gcse_obstack, size);
964 /* Allocate memory for the cuid mapping array,
965 and reg/memory set tracking tables.
967 This is called at the start of each pass. */
969 static void
970 alloc_gcse_mem (rtx f)
972 int i;
973 rtx insn;
975 /* Find the largest UID and create a mapping from UIDs to CUIDs.
976 CUIDs are like UIDs except they increase monotonically, have no gaps,
977 and only apply to real insns. */
979 max_uid = get_max_uid ();
980 uid_cuid = gcalloc (max_uid + 1, sizeof (int));
981 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
983 if (INSN_P (insn))
984 uid_cuid[INSN_UID (insn)] = i++;
985 else
986 uid_cuid[INSN_UID (insn)] = i;
989 /* Create a table mapping cuids to insns. */
991 max_cuid = i;
992 cuid_insn = gcalloc (max_cuid + 1, sizeof (rtx));
993 for (insn = f, i = 0; insn; insn = NEXT_INSN (insn))
994 if (INSN_P (insn))
995 CUID_INSN (i++) = insn;
997 /* Allocate vars to track sets of regs. */
998 reg_set_bitmap = BITMAP_XMALLOC ();
1000 /* Allocate vars to track sets of regs, memory per block. */
1001 reg_set_in_block = sbitmap_vector_alloc (last_basic_block, max_gcse_regno);
1002 /* Allocate array to keep a list of insns which modify memory in each
1003 basic block. */
1004 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
1005 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
1006 modify_mem_list_set = BITMAP_XMALLOC ();
1007 canon_modify_mem_list_set = BITMAP_XMALLOC ();
1010 /* Free memory allocated by alloc_gcse_mem. */
1012 static void
1013 free_gcse_mem (void)
1015 free (uid_cuid);
1016 free (cuid_insn);
1018 BITMAP_XFREE (reg_set_bitmap);
1020 sbitmap_vector_free (reg_set_in_block);
1021 free_modify_mem_tables ();
1022 BITMAP_XFREE (modify_mem_list_set);
1023 BITMAP_XFREE (canon_modify_mem_list_set);
1026 /* Many of the global optimization algorithms work by solving dataflow
1027 equations for various expressions. Initially, some local value is
1028 computed for each expression in each block. Then, the values across the
1029 various blocks are combined (by following flow graph edges) to arrive at
1030 global values. Conceptually, each set of equations is independent. We
1031 may therefore solve all the equations in parallel, solve them one at a
1032 time, or pick any intermediate approach.
1034 When you're going to need N two-dimensional bitmaps, each X (say, the
1035 number of blocks) by Y (say, the number of expressions), call this
1036 function. It's not important what X and Y represent; only that Y
1037 correspond to the things that can be done in parallel. This function will
1038 return an appropriate chunking factor C; you should solve C sets of
1039 equations in parallel. By going through this function, we can easily
1040 trade space against time; by solving fewer equations in parallel we use
1041 less space. */
1043 static int
1044 get_bitmap_width (int n, int x, int y)
1046 /* It's not really worth figuring out *exactly* how much memory will
1047 be used by a particular choice. The important thing is to get
1048 something approximately right. */
1049 size_t max_bitmap_memory = 10 * 1024 * 1024;
1051 /* The number of bytes we'd use for a single column of minimum
1052 width. */
1053 size_t column_size = n * x * sizeof (SBITMAP_ELT_TYPE);
1055 /* Often, it's reasonable just to solve all the equations in
1056 parallel. */
1057 if (column_size * SBITMAP_SET_SIZE (y) <= max_bitmap_memory)
1058 return y;
1060 /* Otherwise, pick the largest width we can, without going over the
1061 limit. */
1062 return SBITMAP_ELT_BITS * ((max_bitmap_memory + column_size - 1)
1063 / column_size);
1066 /* Compute the local properties of each recorded expression.
1068 Local properties are those that are defined by the block, irrespective of
1069 other blocks.
1071 An expression is transparent in a block if its operands are not modified
1072 in the block.
1074 An expression is computed (locally available) in a block if it is computed
1075 at least once and expression would contain the same value if the
1076 computation was moved to the end of the block.
1078 An expression is locally anticipatable in a block if it is computed at
1079 least once and expression would contain the same value if the computation
1080 was moved to the beginning of the block.
1082 We call this routine for cprop, pre and code hoisting. They all compute
1083 basically the same information and thus can easily share this code.
1085 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
1086 properties. If NULL, then it is not necessary to compute or record that
1087 particular property.
1089 TABLE controls which hash table to look at. If it is set hash table,
1090 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
1091 ABSALTERED. */
1093 static void
1094 compute_local_properties (sbitmap *transp, sbitmap *comp, sbitmap *antloc, struct hash_table *table)
1096 unsigned int i;
1098 /* Initialize any bitmaps that were passed in. */
1099 if (transp)
1101 if (table->set_p)
1102 sbitmap_vector_zero (transp, last_basic_block);
1103 else
1104 sbitmap_vector_ones (transp, last_basic_block);
1107 if (comp)
1108 sbitmap_vector_zero (comp, last_basic_block);
1109 if (antloc)
1110 sbitmap_vector_zero (antloc, last_basic_block);
1112 for (i = 0; i < table->size; i++)
1114 struct expr *expr;
1116 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
1118 int indx = expr->bitmap_index;
1119 struct occr *occr;
1121 /* The expression is transparent in this block if it is not killed.
1122 We start by assuming all are transparent [none are killed], and
1123 then reset the bits for those that are. */
1124 if (transp)
1125 compute_transp (expr->expr, indx, transp, table->set_p);
1127 /* The occurrences recorded in antic_occr are exactly those that
1128 we want to set to nonzero in ANTLOC. */
1129 if (antloc)
1130 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
1132 SET_BIT (antloc[BLOCK_NUM (occr->insn)], indx);
1134 /* While we're scanning the table, this is a good place to
1135 initialize this. */
1136 occr->deleted_p = 0;
1139 /* The occurrences recorded in avail_occr are exactly those that
1140 we want to set to nonzero in COMP. */
1141 if (comp)
1142 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
1144 SET_BIT (comp[BLOCK_NUM (occr->insn)], indx);
1146 /* While we're scanning the table, this is a good place to
1147 initialize this. */
1148 occr->copied_p = 0;
1151 /* While we're scanning the table, this is a good place to
1152 initialize this. */
1153 expr->reaching_reg = 0;
1158 /* Register set information.
1160 `reg_set_table' records where each register is set or otherwise
1161 modified. */
1163 static struct obstack reg_set_obstack;
1165 static void
1166 alloc_reg_set_mem (int n_regs)
1168 reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
1169 reg_set_table = gcalloc (reg_set_table_size, sizeof (struct reg_set *));
1171 gcc_obstack_init (&reg_set_obstack);
1174 static void
1175 free_reg_set_mem (void)
1177 free (reg_set_table);
1178 obstack_free (&reg_set_obstack, NULL);
1181 /* An OLD_INSN that used to set REGNO was replaced by NEW_INSN.
1182 Update the corresponding `reg_set_table' entry accordingly.
1183 We assume that NEW_INSN is not already recorded in reg_set_table[regno]. */
1185 static void
1186 replace_one_set (int regno, rtx old_insn, rtx new_insn)
1188 struct reg_set *reg_info;
1189 if (regno >= reg_set_table_size)
1190 return;
1191 for (reg_info = reg_set_table[regno]; reg_info; reg_info = reg_info->next)
1192 if (reg_info->insn == old_insn)
1194 reg_info->insn = new_insn;
1195 break;
1199 /* Record REGNO in the reg_set table. */
1201 static void
1202 record_one_set (int regno, rtx insn)
1204 /* Allocate a new reg_set element and link it onto the list. */
1205 struct reg_set *new_reg_info;
1207 /* If the table isn't big enough, enlarge it. */
1208 if (regno >= reg_set_table_size)
1210 int new_size = regno + REG_SET_TABLE_SLOP;
1212 reg_set_table = grealloc (reg_set_table,
1213 new_size * sizeof (struct reg_set *));
1214 memset (reg_set_table + reg_set_table_size, 0,
1215 (new_size - reg_set_table_size) * sizeof (struct reg_set *));
1216 reg_set_table_size = new_size;
1219 new_reg_info = obstack_alloc (&reg_set_obstack, sizeof (struct reg_set));
1220 bytes_used += sizeof (struct reg_set);
1221 new_reg_info->insn = insn;
1222 new_reg_info->next = reg_set_table[regno];
1223 reg_set_table[regno] = new_reg_info;
1226 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1227 an insn. The DATA is really the instruction in which the SET is
1228 occurring. */
1230 static void
1231 record_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
1233 rtx record_set_insn = (rtx) data;
1235 if (GET_CODE (dest) == REG && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
1236 record_one_set (REGNO (dest), record_set_insn);
1239 /* Scan the function and record each set of each pseudo-register.
1241 This is called once, at the start of the gcse pass. See the comments for
1242 `reg_set_table' for further documentation. */
1244 static void
1245 compute_sets (rtx f)
1247 rtx insn;
1249 for (insn = f; insn != 0; insn = NEXT_INSN (insn))
1250 if (INSN_P (insn))
1251 note_stores (PATTERN (insn), record_set_info, insn);
1254 /* Hash table support. */
1256 struct reg_avail_info
1258 basic_block last_bb;
1259 int first_set;
1260 int last_set;
1263 static struct reg_avail_info *reg_avail_info;
1264 static basic_block current_bb;
1267 /* See whether X, the source of a set, is something we want to consider for
1268 GCSE. */
1270 static GTY(()) rtx test_insn;
1271 static int
1272 want_to_gcse_p (rtx x)
1274 int num_clobbers = 0;
1275 int icode;
1277 switch (GET_CODE (x))
1279 case REG:
1280 case SUBREG:
1281 case CONST_INT:
1282 case CONST_DOUBLE:
1283 case CONST_VECTOR:
1284 case CALL:
1285 case CONSTANT_P_RTX:
1286 return 0;
1288 default:
1289 break;
1292 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1293 if (general_operand (x, GET_MODE (x)))
1294 return 1;
1295 else if (GET_MODE (x) == VOIDmode)
1296 return 0;
1298 /* Otherwise, check if we can make a valid insn from it. First initialize
1299 our test insn if we haven't already. */
1300 if (test_insn == 0)
1302 test_insn
1303 = make_insn_raw (gen_rtx_SET (VOIDmode,
1304 gen_rtx_REG (word_mode,
1305 FIRST_PSEUDO_REGISTER * 2),
1306 const0_rtx));
1307 NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0;
1310 /* Now make an insn like the one we would make when GCSE'ing and see if
1311 valid. */
1312 PUT_MODE (SET_DEST (PATTERN (test_insn)), GET_MODE (x));
1313 SET_SRC (PATTERN (test_insn)) = x;
1314 return ((icode = recog (PATTERN (test_insn), test_insn, &num_clobbers)) >= 0
1315 && (num_clobbers == 0 || ! added_clobbers_hard_reg_p (icode)));
1318 /* Return nonzero if the operands of expression X are unchanged from the
1319 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1320 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1322 static int
1323 oprs_unchanged_p (rtx x, rtx insn, int avail_p)
1325 int i, j;
1326 enum rtx_code code;
1327 const char *fmt;
1329 if (x == 0)
1330 return 1;
1332 code = GET_CODE (x);
1333 switch (code)
1335 case REG:
1337 struct reg_avail_info *info = &reg_avail_info[REGNO (x)];
1339 if (info->last_bb != current_bb)
1340 return 1;
1341 if (avail_p)
1342 return info->last_set < INSN_CUID (insn);
1343 else
1344 return info->first_set >= INSN_CUID (insn);
1347 case MEM:
1348 if (load_killed_in_block_p (current_bb, INSN_CUID (insn),
1349 x, avail_p))
1350 return 0;
1351 else
1352 return oprs_unchanged_p (XEXP (x, 0), insn, avail_p);
1354 case PRE_DEC:
1355 case PRE_INC:
1356 case POST_DEC:
1357 case POST_INC:
1358 case PRE_MODIFY:
1359 case POST_MODIFY:
1360 return 0;
1362 case PC:
1363 case CC0: /*FIXME*/
1364 case CONST:
1365 case CONST_INT:
1366 case CONST_DOUBLE:
1367 case CONST_VECTOR:
1368 case SYMBOL_REF:
1369 case LABEL_REF:
1370 case ADDR_VEC:
1371 case ADDR_DIFF_VEC:
1372 return 1;
1374 default:
1375 break;
1378 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1380 if (fmt[i] == 'e')
1382 /* If we are about to do the last recursive call needed at this
1383 level, change it into iteration. This function is called enough
1384 to be worth it. */
1385 if (i == 0)
1386 return oprs_unchanged_p (XEXP (x, i), insn, avail_p);
1388 else if (! oprs_unchanged_p (XEXP (x, i), insn, avail_p))
1389 return 0;
1391 else if (fmt[i] == 'E')
1392 for (j = 0; j < XVECLEN (x, i); j++)
1393 if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p))
1394 return 0;
1397 return 1;
1400 /* Used for communication between mems_conflict_for_gcse_p and
1401 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1402 conflict between two memory references. */
1403 static int gcse_mems_conflict_p;
1405 /* Used for communication between mems_conflict_for_gcse_p and
1406 load_killed_in_block_p. A memory reference for a load instruction,
1407 mems_conflict_for_gcse_p will see if a memory store conflicts with
1408 this memory load. */
1409 static rtx gcse_mem_operand;
1411 /* DEST is the output of an instruction. If it is a memory reference, and
1412 possibly conflicts with the load found in gcse_mem_operand, then set
1413 gcse_mems_conflict_p to a nonzero value. */
1415 static void
1416 mems_conflict_for_gcse_p (rtx dest, rtx setter ATTRIBUTE_UNUSED,
1417 void *data ATTRIBUTE_UNUSED)
1419 while (GET_CODE (dest) == SUBREG
1420 || GET_CODE (dest) == ZERO_EXTRACT
1421 || GET_CODE (dest) == SIGN_EXTRACT
1422 || GET_CODE (dest) == STRICT_LOW_PART)
1423 dest = XEXP (dest, 0);
1425 /* If DEST is not a MEM, then it will not conflict with the load. Note
1426 that function calls are assumed to clobber memory, but are handled
1427 elsewhere. */
1428 if (GET_CODE (dest) != MEM)
1429 return;
1431 /* If we are setting a MEM in our list of specially recognized MEMs,
1432 don't mark as killed this time. */
1434 if (expr_equiv_p (dest, gcse_mem_operand) && pre_ldst_mems != NULL)
1436 if (!find_rtx_in_ldst (dest))
1437 gcse_mems_conflict_p = 1;
1438 return;
1441 if (true_dependence (dest, GET_MODE (dest), gcse_mem_operand,
1442 rtx_addr_varies_p))
1443 gcse_mems_conflict_p = 1;
1446 /* Return nonzero if the expression in X (a memory reference) is killed
1447 in block BB before or after the insn with the CUID in UID_LIMIT.
1448 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1449 before UID_LIMIT.
1451 To check the entire block, set UID_LIMIT to max_uid + 1 and
1452 AVAIL_P to 0. */
1454 static int
1455 load_killed_in_block_p (basic_block bb, int uid_limit, rtx x, int avail_p)
1457 rtx list_entry = modify_mem_list[bb->index];
1458 while (list_entry)
1460 rtx setter;
1461 /* Ignore entries in the list that do not apply. */
1462 if ((avail_p
1463 && INSN_CUID (XEXP (list_entry, 0)) < uid_limit)
1464 || (! avail_p
1465 && INSN_CUID (XEXP (list_entry, 0)) > uid_limit))
1467 list_entry = XEXP (list_entry, 1);
1468 continue;
1471 setter = XEXP (list_entry, 0);
1473 /* If SETTER is a call everything is clobbered. Note that calls
1474 to pure functions are never put on the list, so we need not
1475 worry about them. */
1476 if (GET_CODE (setter) == CALL_INSN)
1477 return 1;
1479 /* SETTER must be an INSN of some kind that sets memory. Call
1480 note_stores to examine each hunk of memory that is modified.
1482 The note_stores interface is pretty limited, so we have to
1483 communicate via global variables. Yuk. */
1484 gcse_mem_operand = x;
1485 gcse_mems_conflict_p = 0;
1486 note_stores (PATTERN (setter), mems_conflict_for_gcse_p, NULL);
1487 if (gcse_mems_conflict_p)
1488 return 1;
1489 list_entry = XEXP (list_entry, 1);
1491 return 0;
1494 /* Return nonzero if the operands of expression X are unchanged from
1495 the start of INSN's basic block up to but not including INSN. */
1497 static int
1498 oprs_anticipatable_p (rtx x, rtx insn)
1500 return oprs_unchanged_p (x, insn, 0);
1503 /* Return nonzero if the operands of expression X are unchanged from
1504 INSN to the end of INSN's basic block. */
1506 static int
1507 oprs_available_p (rtx x, rtx insn)
1509 return oprs_unchanged_p (x, insn, 1);
1512 /* Hash expression X.
1514 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1515 indicating if a volatile operand is found or if the expression contains
1516 something we don't want to insert in the table.
1518 ??? One might want to merge this with canon_hash. Later. */
1520 static unsigned int
1521 hash_expr (rtx x, enum machine_mode mode, int *do_not_record_p, int hash_table_size)
1523 unsigned int hash;
1525 *do_not_record_p = 0;
1527 hash = hash_expr_1 (x, mode, do_not_record_p);
1528 return hash % hash_table_size;
1531 /* Hash a string. Just add its bytes up. */
1533 static inline unsigned
1534 hash_string_1 (const char *ps)
1536 unsigned hash = 0;
1537 const unsigned char *p = (const unsigned char *) ps;
1539 if (p)
1540 while (*p)
1541 hash += *p++;
1543 return hash;
1546 /* Subroutine of hash_expr to do the actual work. */
1548 static unsigned int
1549 hash_expr_1 (rtx x, enum machine_mode mode, int *do_not_record_p)
1551 int i, j;
1552 unsigned hash = 0;
1553 enum rtx_code code;
1554 const char *fmt;
1556 /* Used to turn recursion into iteration. We can't rely on GCC's
1557 tail-recursion elimination since we need to keep accumulating values
1558 in HASH. */
1560 if (x == 0)
1561 return hash;
1563 repeat:
1564 code = GET_CODE (x);
1565 switch (code)
1567 case REG:
1568 hash += ((unsigned int) REG << 7) + REGNO (x);
1569 return hash;
1571 case CONST_INT:
1572 hash += (((unsigned int) CONST_INT << 7) + (unsigned int) mode
1573 + (unsigned int) INTVAL (x));
1574 return hash;
1576 case CONST_DOUBLE:
1577 /* This is like the general case, except that it only counts
1578 the integers representing the constant. */
1579 hash += (unsigned int) code + (unsigned int) GET_MODE (x);
1580 if (GET_MODE (x) != VOIDmode)
1581 for (i = 2; i < GET_RTX_LENGTH (CONST_DOUBLE); i++)
1582 hash += (unsigned int) XWINT (x, i);
1583 else
1584 hash += ((unsigned int) CONST_DOUBLE_LOW (x)
1585 + (unsigned int) CONST_DOUBLE_HIGH (x));
1586 return hash;
1588 case CONST_VECTOR:
1590 int units;
1591 rtx elt;
1593 units = CONST_VECTOR_NUNITS (x);
1595 for (i = 0; i < units; ++i)
1597 elt = CONST_VECTOR_ELT (x, i);
1598 hash += hash_expr_1 (elt, GET_MODE (elt), do_not_record_p);
1601 return hash;
1604 /* Assume there is only one rtx object for any given label. */
1605 case LABEL_REF:
1606 /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
1607 differences and differences between each stage's debugging dumps. */
1608 hash += (((unsigned int) LABEL_REF << 7)
1609 + CODE_LABEL_NUMBER (XEXP (x, 0)));
1610 return hash;
1612 case SYMBOL_REF:
1614 /* Don't hash on the symbol's address to avoid bootstrap differences.
1615 Different hash values may cause expressions to be recorded in
1616 different orders and thus different registers to be used in the
1617 final assembler. This also avoids differences in the dump files
1618 between various stages. */
1619 unsigned int h = 0;
1620 const unsigned char *p = (const unsigned char *) XSTR (x, 0);
1622 while (*p)
1623 h += (h << 7) + *p++; /* ??? revisit */
1625 hash += ((unsigned int) SYMBOL_REF << 7) + h;
1626 return hash;
1629 case MEM:
1630 if (MEM_VOLATILE_P (x))
1632 *do_not_record_p = 1;
1633 return 0;
1636 hash += (unsigned int) MEM;
1637 /* We used alias set for hashing, but this is not good, since the alias
1638 set may differ in -fprofile-arcs and -fbranch-probabilities compilation
1639 causing the profiles to fail to match. */
1640 x = XEXP (x, 0);
1641 goto repeat;
1643 case PRE_DEC:
1644 case PRE_INC:
1645 case POST_DEC:
1646 case POST_INC:
1647 case PC:
1648 case CC0:
1649 case CALL:
1650 case UNSPEC_VOLATILE:
1651 *do_not_record_p = 1;
1652 return 0;
1654 case ASM_OPERANDS:
1655 if (MEM_VOLATILE_P (x))
1657 *do_not_record_p = 1;
1658 return 0;
1660 else
1662 /* We don't want to take the filename and line into account. */
1663 hash += (unsigned) code + (unsigned) GET_MODE (x)
1664 + hash_string_1 (ASM_OPERANDS_TEMPLATE (x))
1665 + hash_string_1 (ASM_OPERANDS_OUTPUT_CONSTRAINT (x))
1666 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x);
1668 if (ASM_OPERANDS_INPUT_LENGTH (x))
1670 for (i = 1; i < ASM_OPERANDS_INPUT_LENGTH (x); i++)
1672 hash += (hash_expr_1 (ASM_OPERANDS_INPUT (x, i),
1673 GET_MODE (ASM_OPERANDS_INPUT (x, i)),
1674 do_not_record_p)
1675 + hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT
1676 (x, i)));
1679 hash += hash_string_1 (ASM_OPERANDS_INPUT_CONSTRAINT (x, 0));
1680 x = ASM_OPERANDS_INPUT (x, 0);
1681 mode = GET_MODE (x);
1682 goto repeat;
1684 return hash;
1687 default:
1688 break;
1691 hash += (unsigned) code + (unsigned) GET_MODE (x);
1692 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1694 if (fmt[i] == 'e')
1696 /* If we are about to do the last recursive call
1697 needed at this level, change it into iteration.
1698 This function is called enough to be worth it. */
1699 if (i == 0)
1701 x = XEXP (x, i);
1702 goto repeat;
1705 hash += hash_expr_1 (XEXP (x, i), 0, do_not_record_p);
1706 if (*do_not_record_p)
1707 return 0;
1710 else if (fmt[i] == 'E')
1711 for (j = 0; j < XVECLEN (x, i); j++)
1713 hash += hash_expr_1 (XVECEXP (x, i, j), 0, do_not_record_p);
1714 if (*do_not_record_p)
1715 return 0;
1718 else if (fmt[i] == 's')
1719 hash += hash_string_1 (XSTR (x, i));
1720 else if (fmt[i] == 'i')
1721 hash += (unsigned int) XINT (x, i);
1722 else
1723 abort ();
1726 return hash;
1729 /* Hash a set of register REGNO.
1731 Sets are hashed on the register that is set. This simplifies the PRE copy
1732 propagation code.
1734 ??? May need to make things more elaborate. Later, as necessary. */
1736 static unsigned int
1737 hash_set (int regno, int hash_table_size)
1739 unsigned int hash;
1741 hash = regno;
1742 return hash % hash_table_size;
1745 /* Return nonzero if exp1 is equivalent to exp2.
1746 ??? Borrowed from cse.c. Might want to remerge with cse.c. Later. */
1748 static int
1749 expr_equiv_p (rtx x, rtx y)
1751 int i, j;
1752 enum rtx_code code;
1753 const char *fmt;
1755 if (x == y)
1756 return 1;
1758 if (x == 0 || y == 0)
1759 return 0;
1761 code = GET_CODE (x);
1762 if (code != GET_CODE (y))
1763 return 0;
1765 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
1766 if (GET_MODE (x) != GET_MODE (y))
1767 return 0;
1769 switch (code)
1771 case PC:
1772 case CC0:
1773 case CONST_INT:
1774 return 0;
1776 case LABEL_REF:
1777 return XEXP (x, 0) == XEXP (y, 0);
1779 case SYMBOL_REF:
1780 return XSTR (x, 0) == XSTR (y, 0);
1782 case REG:
1783 return REGNO (x) == REGNO (y);
1785 case MEM:
1786 /* Can't merge two expressions in different alias sets, since we can
1787 decide that the expression is transparent in a block when it isn't,
1788 due to it being set with the different alias set. */
1789 if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
1790 return 0;
1792 /* A volatile mem should not be considered equivalent to any other. */
1793 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
1794 return 0;
1795 break;
1797 /* For commutative operations, check both orders. */
1798 case PLUS:
1799 case MULT:
1800 case AND:
1801 case IOR:
1802 case XOR:
1803 case NE:
1804 case EQ:
1805 return ((expr_equiv_p (XEXP (x, 0), XEXP (y, 0))
1806 && expr_equiv_p (XEXP (x, 1), XEXP (y, 1)))
1807 || (expr_equiv_p (XEXP (x, 0), XEXP (y, 1))
1808 && expr_equiv_p (XEXP (x, 1), XEXP (y, 0))));
1810 case ASM_OPERANDS:
1811 /* We don't use the generic code below because we want to
1812 disregard filename and line numbers. */
1814 /* A volatile asm isn't equivalent to any other. */
1815 if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y))
1816 return 0;
1818 if (GET_MODE (x) != GET_MODE (y)
1819 || strcmp (ASM_OPERANDS_TEMPLATE (x), ASM_OPERANDS_TEMPLATE (y))
1820 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x),
1821 ASM_OPERANDS_OUTPUT_CONSTRAINT (y))
1822 || ASM_OPERANDS_OUTPUT_IDX (x) != ASM_OPERANDS_OUTPUT_IDX (y)
1823 || ASM_OPERANDS_INPUT_LENGTH (x) != ASM_OPERANDS_INPUT_LENGTH (y))
1824 return 0;
1826 if (ASM_OPERANDS_INPUT_LENGTH (x))
1828 for (i = ASM_OPERANDS_INPUT_LENGTH (x) - 1; i >= 0; i--)
1829 if (! expr_equiv_p (ASM_OPERANDS_INPUT (x, i),
1830 ASM_OPERANDS_INPUT (y, i))
1831 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x, i),
1832 ASM_OPERANDS_INPUT_CONSTRAINT (y, i)))
1833 return 0;
1836 return 1;
1838 default:
1839 break;
1842 /* Compare the elements. If any pair of corresponding elements
1843 fail to match, return 0 for the whole thing. */
1845 fmt = GET_RTX_FORMAT (code);
1846 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
1848 switch (fmt[i])
1850 case 'e':
1851 if (! expr_equiv_p (XEXP (x, i), XEXP (y, i)))
1852 return 0;
1853 break;
1855 case 'E':
1856 if (XVECLEN (x, i) != XVECLEN (y, i))
1857 return 0;
1858 for (j = 0; j < XVECLEN (x, i); j++)
1859 if (! expr_equiv_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
1860 return 0;
1861 break;
1863 case 's':
1864 if (strcmp (XSTR (x, i), XSTR (y, i)))
1865 return 0;
1866 break;
1868 case 'i':
1869 if (XINT (x, i) != XINT (y, i))
1870 return 0;
1871 break;
1873 case 'w':
1874 if (XWINT (x, i) != XWINT (y, i))
1875 return 0;
1876 break;
1878 case '0':
1879 break;
1881 default:
1882 abort ();
1886 return 1;
1889 /* Insert expression X in INSN in the hash TABLE.
1890 If it is already present, record it as the last occurrence in INSN's
1891 basic block.
1893 MODE is the mode of the value X is being stored into.
1894 It is only used if X is a CONST_INT.
1896 ANTIC_P is nonzero if X is an anticipatable expression.
1897 AVAIL_P is nonzero if X is an available expression. */
1899 static void
1900 insert_expr_in_table (rtx x, enum machine_mode mode, rtx insn, int antic_p,
1901 int avail_p, struct hash_table *table)
1903 int found, do_not_record_p;
1904 unsigned int hash;
1905 struct expr *cur_expr, *last_expr = NULL;
1906 struct occr *antic_occr, *avail_occr;
1907 struct occr *last_occr = NULL;
1909 hash = hash_expr (x, mode, &do_not_record_p, table->size);
1911 /* Do not insert expression in table if it contains volatile operands,
1912 or if hash_expr determines the expression is something we don't want
1913 to or can't handle. */
1914 if (do_not_record_p)
1915 return;
1917 cur_expr = table->table[hash];
1918 found = 0;
1920 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
1922 /* If the expression isn't found, save a pointer to the end of
1923 the list. */
1924 last_expr = cur_expr;
1925 cur_expr = cur_expr->next_same_hash;
1928 if (! found)
1930 cur_expr = gcse_alloc (sizeof (struct expr));
1931 bytes_used += sizeof (struct expr);
1932 if (table->table[hash] == NULL)
1933 /* This is the first pattern that hashed to this index. */
1934 table->table[hash] = cur_expr;
1935 else
1936 /* Add EXPR to end of this hash chain. */
1937 last_expr->next_same_hash = cur_expr;
1939 /* Set the fields of the expr element. */
1940 cur_expr->expr = x;
1941 cur_expr->bitmap_index = table->n_elems++;
1942 cur_expr->next_same_hash = NULL;
1943 cur_expr->antic_occr = NULL;
1944 cur_expr->avail_occr = NULL;
1947 /* Now record the occurrence(s). */
1948 if (antic_p)
1950 antic_occr = cur_expr->antic_occr;
1952 /* Search for another occurrence in the same basic block. */
1953 while (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn))
1955 /* If an occurrence isn't found, save a pointer to the end of
1956 the list. */
1957 last_occr = antic_occr;
1958 antic_occr = antic_occr->next;
1961 if (antic_occr)
1962 /* Found another instance of the expression in the same basic block.
1963 Prefer the currently recorded one. We want the first one in the
1964 block and the block is scanned from start to end. */
1965 ; /* nothing to do */
1966 else
1968 /* First occurrence of this expression in this basic block. */
1969 antic_occr = gcse_alloc (sizeof (struct occr));
1970 bytes_used += sizeof (struct occr);
1971 /* First occurrence of this expression in any block? */
1972 if (cur_expr->antic_occr == NULL)
1973 cur_expr->antic_occr = antic_occr;
1974 else
1975 last_occr->next = antic_occr;
1977 antic_occr->insn = insn;
1978 antic_occr->next = NULL;
1982 if (avail_p)
1984 avail_occr = cur_expr->avail_occr;
1986 /* Search for another occurrence in the same basic block. */
1987 while (avail_occr && BLOCK_NUM (avail_occr->insn) != BLOCK_NUM (insn))
1989 /* If an occurrence isn't found, save a pointer to the end of
1990 the list. */
1991 last_occr = avail_occr;
1992 avail_occr = avail_occr->next;
1995 if (avail_occr)
1996 /* Found another instance of the expression in the same basic block.
1997 Prefer this occurrence to the currently recorded one. We want
1998 the last one in the block and the block is scanned from start
1999 to end. */
2000 avail_occr->insn = insn;
2001 else
2003 /* First occurrence of this expression in this basic block. */
2004 avail_occr = gcse_alloc (sizeof (struct occr));
2005 bytes_used += sizeof (struct occr);
2007 /* First occurrence of this expression in any block? */
2008 if (cur_expr->avail_occr == NULL)
2009 cur_expr->avail_occr = avail_occr;
2010 else
2011 last_occr->next = avail_occr;
2013 avail_occr->insn = insn;
2014 avail_occr->next = NULL;
2019 /* Insert pattern X in INSN in the hash table.
2020 X is a SET of a reg to either another reg or a constant.
2021 If it is already present, record it as the last occurrence in INSN's
2022 basic block. */
2024 static void
2025 insert_set_in_table (rtx x, rtx insn, struct hash_table *table)
2027 int found;
2028 unsigned int hash;
2029 struct expr *cur_expr, *last_expr = NULL;
2030 struct occr *cur_occr, *last_occr = NULL;
2032 if (GET_CODE (x) != SET
2033 || GET_CODE (SET_DEST (x)) != REG)
2034 abort ();
2036 hash = hash_set (REGNO (SET_DEST (x)), table->size);
2038 cur_expr = table->table[hash];
2039 found = 0;
2041 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
2043 /* If the expression isn't found, save a pointer to the end of
2044 the list. */
2045 last_expr = cur_expr;
2046 cur_expr = cur_expr->next_same_hash;
2049 if (! found)
2051 cur_expr = gcse_alloc (sizeof (struct expr));
2052 bytes_used += sizeof (struct expr);
2053 if (table->table[hash] == NULL)
2054 /* This is the first pattern that hashed to this index. */
2055 table->table[hash] = cur_expr;
2056 else
2057 /* Add EXPR to end of this hash chain. */
2058 last_expr->next_same_hash = cur_expr;
2060 /* Set the fields of the expr element.
2061 We must copy X because it can be modified when copy propagation is
2062 performed on its operands. */
2063 cur_expr->expr = copy_rtx (x);
2064 cur_expr->bitmap_index = table->n_elems++;
2065 cur_expr->next_same_hash = NULL;
2066 cur_expr->antic_occr = NULL;
2067 cur_expr->avail_occr = NULL;
2070 /* Now record the occurrence. */
2071 cur_occr = cur_expr->avail_occr;
2073 /* Search for another occurrence in the same basic block. */
2074 while (cur_occr && BLOCK_NUM (cur_occr->insn) != BLOCK_NUM (insn))
2076 /* If an occurrence isn't found, save a pointer to the end of
2077 the list. */
2078 last_occr = cur_occr;
2079 cur_occr = cur_occr->next;
2082 if (cur_occr)
2083 /* Found another instance of the expression in the same basic block.
2084 Prefer this occurrence to the currently recorded one. We want the
2085 last one in the block and the block is scanned from start to end. */
2086 cur_occr->insn = insn;
2087 else
2089 /* First occurrence of this expression in this basic block. */
2090 cur_occr = gcse_alloc (sizeof (struct occr));
2091 bytes_used += sizeof (struct occr);
2093 /* First occurrence of this expression in any block? */
2094 if (cur_expr->avail_occr == NULL)
2095 cur_expr->avail_occr = cur_occr;
2096 else
2097 last_occr->next = cur_occr;
2099 cur_occr->insn = insn;
2100 cur_occr->next = NULL;
2104 /* Determine whether the rtx X should be treated as a constant for
2105 the purposes of GCSE's constant propagation. */
2107 static bool
2108 gcse_constant_p (rtx x)
2110 /* Consider a COMPARE of two integers constant. */
2111 if (GET_CODE (x) == COMPARE
2112 && GET_CODE (XEXP (x, 0)) == CONST_INT
2113 && GET_CODE (XEXP (x, 1)) == CONST_INT)
2114 return true;
2117 /* Consider a COMPARE of the same registers is a constant
2118 if they are not floating point registers. */
2119 if (GET_CODE(x) == COMPARE
2120 && GET_CODE (XEXP (x, 0)) == REG
2121 && GET_CODE (XEXP (x, 1)) == REG
2122 && REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 1))
2123 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 0)))
2124 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 1))))
2125 return true;
2127 if (GET_CODE (x) == CONSTANT_P_RTX)
2128 return false;
2130 return CONSTANT_P (x);
2133 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
2134 expression one). */
2136 static void
2137 hash_scan_set (rtx pat, rtx insn, struct hash_table *table)
2139 rtx src = SET_SRC (pat);
2140 rtx dest = SET_DEST (pat);
2141 rtx note;
2143 if (GET_CODE (src) == CALL)
2144 hash_scan_call (src, insn, table);
2146 else if (GET_CODE (dest) == REG)
2148 unsigned int regno = REGNO (dest);
2149 rtx tmp;
2151 /* If this is a single set and we are doing constant propagation,
2152 see if a REG_NOTE shows this equivalent to a constant. */
2153 if (table->set_p && (note = find_reg_equal_equiv_note (insn)) != 0
2154 && gcse_constant_p (XEXP (note, 0)))
2155 src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src);
2157 /* Only record sets of pseudo-regs in the hash table. */
2158 if (! table->set_p
2159 && regno >= FIRST_PSEUDO_REGISTER
2160 /* Don't GCSE something if we can't do a reg/reg copy. */
2161 && can_copy_p (GET_MODE (dest))
2162 /* GCSE commonly inserts instruction after the insn. We can't
2163 do that easily for EH_REGION notes so disable GCSE on these
2164 for now. */
2165 && !find_reg_note (insn, REG_EH_REGION, NULL_RTX)
2166 /* Is SET_SRC something we want to gcse? */
2167 && want_to_gcse_p (src)
2168 /* Don't CSE a nop. */
2169 && ! set_noop_p (pat)
2170 /* Don't GCSE if it has attached REG_EQUIV note.
2171 At this point this only function parameters should have
2172 REG_EQUIV notes and if the argument slot is used somewhere
2173 explicitly, it means address of parameter has been taken,
2174 so we should not extend the lifetime of the pseudo. */
2175 && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
2176 || GET_CODE (XEXP (note, 0)) != MEM))
2178 /* An expression is not anticipatable if its operands are
2179 modified before this insn or if this is not the only SET in
2180 this insn. */
2181 int antic_p = oprs_anticipatable_p (src, insn) && single_set (insn);
2182 /* An expression is not available if its operands are
2183 subsequently modified, including this insn. It's also not
2184 available if this is a branch, because we can't insert
2185 a set after the branch. */
2186 int avail_p = (oprs_available_p (src, insn)
2187 && ! JUMP_P (insn));
2189 insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p, table);
2192 /* Record sets for constant/copy propagation. */
2193 else if (table->set_p
2194 && regno >= FIRST_PSEUDO_REGISTER
2195 && ((GET_CODE (src) == REG
2196 && REGNO (src) >= FIRST_PSEUDO_REGISTER
2197 && can_copy_p (GET_MODE (dest))
2198 && REGNO (src) != regno)
2199 || gcse_constant_p (src))
2200 /* A copy is not available if its src or dest is subsequently
2201 modified. Here we want to search from INSN+1 on, but
2202 oprs_available_p searches from INSN on. */
2203 && (insn == BLOCK_END (BLOCK_NUM (insn))
2204 || ((tmp = next_nonnote_insn (insn)) != NULL_RTX
2205 && oprs_available_p (pat, tmp))))
2206 insert_set_in_table (pat, insn, table);
2208 /* In case of store we want to consider the memory value as avaiable in
2209 the REG stored in that memory. This makes it possible to remove
2210 redundant loads from due to stores to the same location. */
2211 else if (flag_gcse_las && GET_CODE (src) == REG && GET_CODE (dest) == MEM)
2213 unsigned int regno = REGNO (src);
2215 /* Do not do this for constant/copy propagation. */
2216 if (! table->set_p
2217 /* Only record sets of pseudo-regs in the hash table. */
2218 && regno >= FIRST_PSEUDO_REGISTER
2219 /* Don't GCSE something if we can't do a reg/reg copy. */
2220 && can_copy_p (GET_MODE (src))
2221 /* GCSE commonly inserts instruction after the insn. We can't
2222 do that easily for EH_REGION notes so disable GCSE on these
2223 for now. */
2224 && ! find_reg_note (insn, REG_EH_REGION, NULL_RTX)
2225 /* Is SET_DEST something we want to gcse? */
2226 && want_to_gcse_p (dest)
2227 /* Don't CSE a nop. */
2228 && ! set_noop_p (pat)
2229 /* Don't GCSE if it has attached REG_EQUIV note.
2230 At this point this only function parameters should have
2231 REG_EQUIV notes and if the argument slot is used somewhere
2232 explicitly, it means address of parameter has been taken,
2233 so we should not extend the lifetime of the pseudo. */
2234 && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
2235 || GET_CODE (XEXP (note, 0)) != MEM))
2237 /* Stores are never anticipatable. */
2238 int antic_p = 0;
2239 /* An expression is not available if its operands are
2240 subsequently modified, including this insn. It's also not
2241 available if this is a branch, because we can't insert
2242 a set after the branch. */
2243 int avail_p = oprs_available_p (dest, insn)
2244 && ! JUMP_P (insn);
2246 /* Record the memory expression (DEST) in the hash table. */
2247 insert_expr_in_table (dest, GET_MODE (dest), insn,
2248 antic_p, avail_p, table);
2253 static void
2254 hash_scan_clobber (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
2255 struct hash_table *table ATTRIBUTE_UNUSED)
2257 /* Currently nothing to do. */
2260 static void
2261 hash_scan_call (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
2262 struct hash_table *table ATTRIBUTE_UNUSED)
2264 /* Currently nothing to do. */
2267 /* Process INSN and add hash table entries as appropriate.
2269 Only available expressions that set a single pseudo-reg are recorded.
2271 Single sets in a PARALLEL could be handled, but it's an extra complication
2272 that isn't dealt with right now. The trick is handling the CLOBBERs that
2273 are also in the PARALLEL. Later.
2275 If SET_P is nonzero, this is for the assignment hash table,
2276 otherwise it is for the expression hash table.
2277 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
2278 not record any expressions. */
2280 static void
2281 hash_scan_insn (rtx insn, struct hash_table *table, int in_libcall_block)
2283 rtx pat = PATTERN (insn);
2284 int i;
2286 if (in_libcall_block)
2287 return;
2289 /* Pick out the sets of INSN and for other forms of instructions record
2290 what's been modified. */
2292 if (GET_CODE (pat) == SET)
2293 hash_scan_set (pat, insn, table);
2294 else if (GET_CODE (pat) == PARALLEL)
2295 for (i = 0; i < XVECLEN (pat, 0); i++)
2297 rtx x = XVECEXP (pat, 0, i);
2299 if (GET_CODE (x) == SET)
2300 hash_scan_set (x, insn, table);
2301 else if (GET_CODE (x) == CLOBBER)
2302 hash_scan_clobber (x, insn, table);
2303 else if (GET_CODE (x) == CALL)
2304 hash_scan_call (x, insn, table);
2307 else if (GET_CODE (pat) == CLOBBER)
2308 hash_scan_clobber (pat, insn, table);
2309 else if (GET_CODE (pat) == CALL)
2310 hash_scan_call (pat, insn, table);
2313 static void
2314 dump_hash_table (FILE *file, const char *name, struct hash_table *table)
2316 int i;
2317 /* Flattened out table, so it's printed in proper order. */
2318 struct expr **flat_table;
2319 unsigned int *hash_val;
2320 struct expr *expr;
2322 flat_table = xcalloc (table->n_elems, sizeof (struct expr *));
2323 hash_val = xmalloc (table->n_elems * sizeof (unsigned int));
2325 for (i = 0; i < (int) table->size; i++)
2326 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
2328 flat_table[expr->bitmap_index] = expr;
2329 hash_val[expr->bitmap_index] = i;
2332 fprintf (file, "%s hash table (%d buckets, %d entries)\n",
2333 name, table->size, table->n_elems);
2335 for (i = 0; i < (int) table->n_elems; i++)
2336 if (flat_table[i] != 0)
2338 expr = flat_table[i];
2339 fprintf (file, "Index %d (hash value %d)\n ",
2340 expr->bitmap_index, hash_val[i]);
2341 print_rtl (file, expr->expr);
2342 fprintf (file, "\n");
2345 fprintf (file, "\n");
2347 free (flat_table);
2348 free (hash_val);
2351 /* Record register first/last/block set information for REGNO in INSN.
2353 first_set records the first place in the block where the register
2354 is set and is used to compute "anticipatability".
2356 last_set records the last place in the block where the register
2357 is set and is used to compute "availability".
2359 last_bb records the block for which first_set and last_set are
2360 valid, as a quick test to invalidate them.
2362 reg_set_in_block records whether the register is set in the block
2363 and is used to compute "transparency". */
2365 static void
2366 record_last_reg_set_info (rtx insn, int regno)
2368 struct reg_avail_info *info = &reg_avail_info[regno];
2369 int cuid = INSN_CUID (insn);
2371 info->last_set = cuid;
2372 if (info->last_bb != current_bb)
2374 info->last_bb = current_bb;
2375 info->first_set = cuid;
2376 SET_BIT (reg_set_in_block[current_bb->index], regno);
2381 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
2382 Note we store a pair of elements in the list, so they have to be
2383 taken off pairwise. */
2385 static void
2386 canon_list_insert (rtx dest ATTRIBUTE_UNUSED, rtx unused1 ATTRIBUTE_UNUSED,
2387 void * v_insn)
2389 rtx dest_addr, insn;
2390 int bb;
2392 while (GET_CODE (dest) == SUBREG
2393 || GET_CODE (dest) == ZERO_EXTRACT
2394 || GET_CODE (dest) == SIGN_EXTRACT
2395 || GET_CODE (dest) == STRICT_LOW_PART)
2396 dest = XEXP (dest, 0);
2398 /* If DEST is not a MEM, then it will not conflict with a load. Note
2399 that function calls are assumed to clobber memory, but are handled
2400 elsewhere. */
2402 if (GET_CODE (dest) != MEM)
2403 return;
2405 dest_addr = get_addr (XEXP (dest, 0));
2406 dest_addr = canon_rtx (dest_addr);
2407 insn = (rtx) v_insn;
2408 bb = BLOCK_NUM (insn);
2410 canon_modify_mem_list[bb] =
2411 alloc_EXPR_LIST (VOIDmode, dest_addr, canon_modify_mem_list[bb]);
2412 canon_modify_mem_list[bb] =
2413 alloc_EXPR_LIST (VOIDmode, dest, canon_modify_mem_list[bb]);
2414 bitmap_set_bit (canon_modify_mem_list_set, bb);
2417 /* Record memory modification information for INSN. We do not actually care
2418 about the memory location(s) that are set, or even how they are set (consider
2419 a CALL_INSN). We merely need to record which insns modify memory. */
2421 static void
2422 record_last_mem_set_info (rtx insn)
2424 int bb = BLOCK_NUM (insn);
2426 /* load_killed_in_block_p will handle the case of calls clobbering
2427 everything. */
2428 modify_mem_list[bb] = alloc_INSN_LIST (insn, modify_mem_list[bb]);
2429 bitmap_set_bit (modify_mem_list_set, bb);
2431 if (GET_CODE (insn) == CALL_INSN)
2433 /* Note that traversals of this loop (other than for free-ing)
2434 will break after encountering a CALL_INSN. So, there's no
2435 need to insert a pair of items, as canon_list_insert does. */
2436 canon_modify_mem_list[bb] =
2437 alloc_INSN_LIST (insn, canon_modify_mem_list[bb]);
2438 bitmap_set_bit (canon_modify_mem_list_set, bb);
2440 else
2441 note_stores (PATTERN (insn), canon_list_insert, (void*) insn);
2444 /* Called from compute_hash_table via note_stores to handle one
2445 SET or CLOBBER in an insn. DATA is really the instruction in which
2446 the SET is taking place. */
2448 static void
2449 record_last_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED, void *data)
2451 rtx last_set_insn = (rtx) data;
2453 if (GET_CODE (dest) == SUBREG)
2454 dest = SUBREG_REG (dest);
2456 if (GET_CODE (dest) == REG)
2457 record_last_reg_set_info (last_set_insn, REGNO (dest));
2458 else if (GET_CODE (dest) == MEM
2459 /* Ignore pushes, they clobber nothing. */
2460 && ! push_operand (dest, GET_MODE (dest)))
2461 record_last_mem_set_info (last_set_insn);
2464 /* Top level function to create an expression or assignment hash table.
2466 Expression entries are placed in the hash table if
2467 - they are of the form (set (pseudo-reg) src),
2468 - src is something we want to perform GCSE on,
2469 - none of the operands are subsequently modified in the block
2471 Assignment entries are placed in the hash table if
2472 - they are of the form (set (pseudo-reg) src),
2473 - src is something we want to perform const/copy propagation on,
2474 - none of the operands or target are subsequently modified in the block
2476 Currently src must be a pseudo-reg or a const_int.
2478 TABLE is the table computed. */
2480 static void
2481 compute_hash_table_work (struct hash_table *table)
2483 unsigned int i;
2485 /* While we compute the hash table we also compute a bit array of which
2486 registers are set in which blocks.
2487 ??? This isn't needed during const/copy propagation, but it's cheap to
2488 compute. Later. */
2489 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
2491 /* re-Cache any INSN_LIST nodes we have allocated. */
2492 clear_modify_mem_tables ();
2493 /* Some working arrays used to track first and last set in each block. */
2494 reg_avail_info = gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
2496 for (i = 0; i < max_gcse_regno; ++i)
2497 reg_avail_info[i].last_bb = NULL;
2499 FOR_EACH_BB (current_bb)
2501 rtx insn;
2502 unsigned int regno;
2503 int in_libcall_block;
2505 /* First pass over the instructions records information used to
2506 determine when registers and memory are first and last set.
2507 ??? hard-reg reg_set_in_block computation
2508 could be moved to compute_sets since they currently don't change. */
2510 for (insn = current_bb->head;
2511 insn && insn != NEXT_INSN (current_bb->end);
2512 insn = NEXT_INSN (insn))
2514 if (! INSN_P (insn))
2515 continue;
2517 if (GET_CODE (insn) == CALL_INSN)
2519 bool clobbers_all = false;
2520 #ifdef NON_SAVING_SETJMP
2521 if (NON_SAVING_SETJMP
2522 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
2523 clobbers_all = true;
2524 #endif
2526 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2527 if (clobbers_all
2528 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2529 record_last_reg_set_info (insn, regno);
2531 mark_call (insn);
2534 note_stores (PATTERN (insn), record_last_set_info, insn);
2537 /* Insert implicit sets in the hash table. */
2538 if (table->set_p
2539 && implicit_sets[current_bb->index] != NULL_RTX)
2540 hash_scan_set (implicit_sets[current_bb->index],
2541 current_bb->head, table);
2543 /* The next pass builds the hash table. */
2545 for (insn = current_bb->head, in_libcall_block = 0;
2546 insn && insn != NEXT_INSN (current_bb->end);
2547 insn = NEXT_INSN (insn))
2548 if (INSN_P (insn))
2550 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2551 in_libcall_block = 1;
2552 else if (table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2553 in_libcall_block = 0;
2554 hash_scan_insn (insn, table, in_libcall_block);
2555 if (!table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2556 in_libcall_block = 0;
2560 free (reg_avail_info);
2561 reg_avail_info = NULL;
2564 /* Allocate space for the set/expr hash TABLE.
2565 N_INSNS is the number of instructions in the function.
2566 It is used to determine the number of buckets to use.
2567 SET_P determines whether set or expression table will
2568 be created. */
2570 static void
2571 alloc_hash_table (int n_insns, struct hash_table *table, int set_p)
2573 int n;
2575 table->size = n_insns / 4;
2576 if (table->size < 11)
2577 table->size = 11;
2579 /* Attempt to maintain efficient use of hash table.
2580 Making it an odd number is simplest for now.
2581 ??? Later take some measurements. */
2582 table->size |= 1;
2583 n = table->size * sizeof (struct expr *);
2584 table->table = gmalloc (n);
2585 table->set_p = set_p;
2588 /* Free things allocated by alloc_hash_table. */
2590 static void
2591 free_hash_table (struct hash_table *table)
2593 free (table->table);
2596 /* Compute the hash TABLE for doing copy/const propagation or
2597 expression hash table. */
2599 static void
2600 compute_hash_table (struct hash_table *table)
2602 /* Initialize count of number of entries in hash table. */
2603 table->n_elems = 0;
2604 memset (table->table, 0, table->size * sizeof (struct expr *));
2606 compute_hash_table_work (table);
2609 /* Expression tracking support. */
2611 /* Lookup pattern PAT in the expression TABLE.
2612 The result is a pointer to the table entry, or NULL if not found. */
2614 static struct expr *
2615 lookup_expr (rtx pat, struct hash_table *table)
2617 int do_not_record_p;
2618 unsigned int hash = hash_expr (pat, GET_MODE (pat), &do_not_record_p,
2619 table->size);
2620 struct expr *expr;
2622 if (do_not_record_p)
2623 return NULL;
2625 expr = table->table[hash];
2627 while (expr && ! expr_equiv_p (expr->expr, pat))
2628 expr = expr->next_same_hash;
2630 return expr;
2633 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2634 table entry, or NULL if not found. */
2636 static struct expr *
2637 lookup_set (unsigned int regno, struct hash_table *table)
2639 unsigned int hash = hash_set (regno, table->size);
2640 struct expr *expr;
2642 expr = table->table[hash];
2644 while (expr && REGNO (SET_DEST (expr->expr)) != regno)
2645 expr = expr->next_same_hash;
2647 return expr;
2650 /* Return the next entry for REGNO in list EXPR. */
2652 static struct expr *
2653 next_set (unsigned int regno, struct expr *expr)
2656 expr = expr->next_same_hash;
2657 while (expr && REGNO (SET_DEST (expr->expr)) != regno);
2659 return expr;
2662 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2663 types may be mixed. */
2665 static void
2666 free_insn_expr_list_list (rtx *listp)
2668 rtx list, next;
2670 for (list = *listp; list ; list = next)
2672 next = XEXP (list, 1);
2673 if (GET_CODE (list) == EXPR_LIST)
2674 free_EXPR_LIST_node (list);
2675 else
2676 free_INSN_LIST_node (list);
2679 *listp = NULL;
2682 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2683 static void
2684 clear_modify_mem_tables (void)
2686 int i;
2688 EXECUTE_IF_SET_IN_BITMAP
2689 (modify_mem_list_set, 0, i, free_INSN_LIST_list (modify_mem_list + i));
2690 bitmap_clear (modify_mem_list_set);
2692 EXECUTE_IF_SET_IN_BITMAP
2693 (canon_modify_mem_list_set, 0, i,
2694 free_insn_expr_list_list (canon_modify_mem_list + i));
2695 bitmap_clear (canon_modify_mem_list_set);
2698 /* Release memory used by modify_mem_list_set and canon_modify_mem_list_set. */
2700 static void
2701 free_modify_mem_tables (void)
2703 clear_modify_mem_tables ();
2704 free (modify_mem_list);
2705 free (canon_modify_mem_list);
2706 modify_mem_list = 0;
2707 canon_modify_mem_list = 0;
2710 /* Reset tables used to keep track of what's still available [since the
2711 start of the block]. */
2713 static void
2714 reset_opr_set_tables (void)
2716 /* Maintain a bitmap of which regs have been set since beginning of
2717 the block. */
2718 CLEAR_REG_SET (reg_set_bitmap);
2720 /* Also keep a record of the last instruction to modify memory.
2721 For now this is very trivial, we only record whether any memory
2722 location has been modified. */
2723 clear_modify_mem_tables ();
2726 /* Return nonzero if the operands of X are not set before INSN in
2727 INSN's basic block. */
2729 static int
2730 oprs_not_set_p (rtx x, rtx insn)
2732 int i, j;
2733 enum rtx_code code;
2734 const char *fmt;
2736 if (x == 0)
2737 return 1;
2739 code = GET_CODE (x);
2740 switch (code)
2742 case PC:
2743 case CC0:
2744 case CONST:
2745 case CONST_INT:
2746 case CONST_DOUBLE:
2747 case CONST_VECTOR:
2748 case SYMBOL_REF:
2749 case LABEL_REF:
2750 case ADDR_VEC:
2751 case ADDR_DIFF_VEC:
2752 return 1;
2754 case MEM:
2755 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn),
2756 INSN_CUID (insn), x, 0))
2757 return 0;
2758 else
2759 return oprs_not_set_p (XEXP (x, 0), insn);
2761 case REG:
2762 return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x));
2764 default:
2765 break;
2768 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2770 if (fmt[i] == 'e')
2772 /* If we are about to do the last recursive call
2773 needed at this level, change it into iteration.
2774 This function is called enough to be worth it. */
2775 if (i == 0)
2776 return oprs_not_set_p (XEXP (x, i), insn);
2778 if (! oprs_not_set_p (XEXP (x, i), insn))
2779 return 0;
2781 else if (fmt[i] == 'E')
2782 for (j = 0; j < XVECLEN (x, i); j++)
2783 if (! oprs_not_set_p (XVECEXP (x, i, j), insn))
2784 return 0;
2787 return 1;
2790 /* Mark things set by a CALL. */
2792 static void
2793 mark_call (rtx insn)
2795 if (! CONST_OR_PURE_CALL_P (insn))
2796 record_last_mem_set_info (insn);
2799 /* Mark things set by a SET. */
2801 static void
2802 mark_set (rtx pat, rtx insn)
2804 rtx dest = SET_DEST (pat);
2806 while (GET_CODE (dest) == SUBREG
2807 || GET_CODE (dest) == ZERO_EXTRACT
2808 || GET_CODE (dest) == SIGN_EXTRACT
2809 || GET_CODE (dest) == STRICT_LOW_PART)
2810 dest = XEXP (dest, 0);
2812 if (GET_CODE (dest) == REG)
2813 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (dest));
2814 else if (GET_CODE (dest) == MEM)
2815 record_last_mem_set_info (insn);
2817 if (GET_CODE (SET_SRC (pat)) == CALL)
2818 mark_call (insn);
2821 /* Record things set by a CLOBBER. */
2823 static void
2824 mark_clobber (rtx pat, rtx insn)
2826 rtx clob = XEXP (pat, 0);
2828 while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART)
2829 clob = XEXP (clob, 0);
2831 if (GET_CODE (clob) == REG)
2832 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (clob));
2833 else
2834 record_last_mem_set_info (insn);
2837 /* Record things set by INSN.
2838 This data is used by oprs_not_set_p. */
2840 static void
2841 mark_oprs_set (rtx insn)
2843 rtx pat = PATTERN (insn);
2844 int i;
2846 if (GET_CODE (pat) == SET)
2847 mark_set (pat, insn);
2848 else if (GET_CODE (pat) == PARALLEL)
2849 for (i = 0; i < XVECLEN (pat, 0); i++)
2851 rtx x = XVECEXP (pat, 0, i);
2853 if (GET_CODE (x) == SET)
2854 mark_set (x, insn);
2855 else if (GET_CODE (x) == CLOBBER)
2856 mark_clobber (x, insn);
2857 else if (GET_CODE (x) == CALL)
2858 mark_call (insn);
2861 else if (GET_CODE (pat) == CLOBBER)
2862 mark_clobber (pat, insn);
2863 else if (GET_CODE (pat) == CALL)
2864 mark_call (insn);
2868 /* Classic GCSE reaching definition support. */
2870 /* Allocate reaching def variables. */
2872 static void
2873 alloc_rd_mem (int n_blocks, int n_insns)
2875 rd_kill = sbitmap_vector_alloc (n_blocks, n_insns);
2876 sbitmap_vector_zero (rd_kill, n_blocks);
2878 rd_gen = sbitmap_vector_alloc (n_blocks, n_insns);
2879 sbitmap_vector_zero (rd_gen, n_blocks);
2881 reaching_defs = sbitmap_vector_alloc (n_blocks, n_insns);
2882 sbitmap_vector_zero (reaching_defs, n_blocks);
2884 rd_out = sbitmap_vector_alloc (n_blocks, n_insns);
2885 sbitmap_vector_zero (rd_out, n_blocks);
2888 /* Free reaching def variables. */
2890 static void
2891 free_rd_mem (void)
2893 sbitmap_vector_free (rd_kill);
2894 sbitmap_vector_free (rd_gen);
2895 sbitmap_vector_free (reaching_defs);
2896 sbitmap_vector_free (rd_out);
2899 /* Add INSN to the kills of BB. REGNO, set in BB, is killed by INSN. */
2901 static void
2902 handle_rd_kill_set (rtx insn, int regno, basic_block bb)
2904 struct reg_set *this_reg;
2906 for (this_reg = reg_set_table[regno]; this_reg; this_reg = this_reg ->next)
2907 if (BLOCK_NUM (this_reg->insn) != BLOCK_NUM (insn))
2908 SET_BIT (rd_kill[bb->index], INSN_CUID (this_reg->insn));
2911 /* Compute the set of kill's for reaching definitions. */
2913 static void
2914 compute_kill_rd (void)
2916 int cuid;
2917 unsigned int regno;
2918 int i;
2919 basic_block bb;
2921 /* For each block
2922 For each set bit in `gen' of the block (i.e each insn which
2923 generates a definition in the block)
2924 Call the reg set by the insn corresponding to that bit regx
2925 Look at the linked list starting at reg_set_table[regx]
2926 For each setting of regx in the linked list, which is not in
2927 this block
2928 Set the bit in `kill' corresponding to that insn. */
2929 FOR_EACH_BB (bb)
2930 for (cuid = 0; cuid < max_cuid; cuid++)
2931 if (TEST_BIT (rd_gen[bb->index], cuid))
2933 rtx insn = CUID_INSN (cuid);
2934 rtx pat = PATTERN (insn);
2936 if (GET_CODE (insn) == CALL_INSN)
2938 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2939 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2940 handle_rd_kill_set (insn, regno, bb);
2943 if (GET_CODE (pat) == PARALLEL)
2945 for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
2947 enum rtx_code code = GET_CODE (XVECEXP (pat, 0, i));
2949 if ((code == SET || code == CLOBBER)
2950 && GET_CODE (XEXP (XVECEXP (pat, 0, i), 0)) == REG)
2951 handle_rd_kill_set (insn,
2952 REGNO (XEXP (XVECEXP (pat, 0, i), 0)),
2953 bb);
2956 else if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == REG)
2957 /* Each setting of this register outside of this block
2958 must be marked in the set of kills in this block. */
2959 handle_rd_kill_set (insn, REGNO (SET_DEST (pat)), bb);
2963 /* Compute the reaching definitions as in
2964 Compilers Principles, Techniques, and Tools. Aho, Sethi, Ullman,
2965 Chapter 10. It is the same algorithm as used for computing available
2966 expressions but applied to the gens and kills of reaching definitions. */
2968 static void
2969 compute_rd (void)
2971 int changed, passes;
2972 basic_block bb;
2974 FOR_EACH_BB (bb)
2975 sbitmap_copy (rd_out[bb->index] /*dst*/, rd_gen[bb->index] /*src*/);
2977 passes = 0;
2978 changed = 1;
2979 while (changed)
2981 changed = 0;
2982 FOR_EACH_BB (bb)
2984 sbitmap_union_of_preds (reaching_defs[bb->index], rd_out, bb->index);
2985 changed |= sbitmap_union_of_diff_cg (rd_out[bb->index], rd_gen[bb->index],
2986 reaching_defs[bb->index], rd_kill[bb->index]);
2988 passes++;
2991 if (gcse_file)
2992 fprintf (gcse_file, "reaching def computation: %d passes\n", passes);
2995 /* Classic GCSE available expression support. */
2997 /* Allocate memory for available expression computation. */
2999 static void
3000 alloc_avail_expr_mem (int n_blocks, int n_exprs)
3002 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
3003 sbitmap_vector_zero (ae_kill, n_blocks);
3005 ae_gen = sbitmap_vector_alloc (n_blocks, n_exprs);
3006 sbitmap_vector_zero (ae_gen, n_blocks);
3008 ae_in = sbitmap_vector_alloc (n_blocks, n_exprs);
3009 sbitmap_vector_zero (ae_in, n_blocks);
3011 ae_out = sbitmap_vector_alloc (n_blocks, n_exprs);
3012 sbitmap_vector_zero (ae_out, n_blocks);
3015 static void
3016 free_avail_expr_mem (void)
3018 sbitmap_vector_free (ae_kill);
3019 sbitmap_vector_free (ae_gen);
3020 sbitmap_vector_free (ae_in);
3021 sbitmap_vector_free (ae_out);
3024 /* Compute the set of available expressions generated in each basic block. */
3026 static void
3027 compute_ae_gen (struct hash_table *expr_hash_table)
3029 unsigned int i;
3030 struct expr *expr;
3031 struct occr *occr;
3033 /* For each recorded occurrence of each expression, set ae_gen[bb][expr].
3034 This is all we have to do because an expression is not recorded if it
3035 is not available, and the only expressions we want to work with are the
3036 ones that are recorded. */
3037 for (i = 0; i < expr_hash_table->size; i++)
3038 for (expr = expr_hash_table->table[i]; expr != 0; expr = expr->next_same_hash)
3039 for (occr = expr->avail_occr; occr != 0; occr = occr->next)
3040 SET_BIT (ae_gen[BLOCK_NUM (occr->insn)], expr->bitmap_index);
3043 /* Return nonzero if expression X is killed in BB. */
3045 static int
3046 expr_killed_p (rtx x, basic_block bb)
3048 int i, j;
3049 enum rtx_code code;
3050 const char *fmt;
3052 if (x == 0)
3053 return 1;
3055 code = GET_CODE (x);
3056 switch (code)
3058 case REG:
3059 return TEST_BIT (reg_set_in_block[bb->index], REGNO (x));
3061 case MEM:
3062 if (load_killed_in_block_p (bb, get_max_uid () + 1, x, 0))
3063 return 1;
3064 else
3065 return expr_killed_p (XEXP (x, 0), bb);
3067 case PC:
3068 case CC0: /*FIXME*/
3069 case CONST:
3070 case CONST_INT:
3071 case CONST_DOUBLE:
3072 case CONST_VECTOR:
3073 case SYMBOL_REF:
3074 case LABEL_REF:
3075 case ADDR_VEC:
3076 case ADDR_DIFF_VEC:
3077 return 0;
3079 default:
3080 break;
3083 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3085 if (fmt[i] == 'e')
3087 /* If we are about to do the last recursive call
3088 needed at this level, change it into iteration.
3089 This function is called enough to be worth it. */
3090 if (i == 0)
3091 return expr_killed_p (XEXP (x, i), bb);
3092 else if (expr_killed_p (XEXP (x, i), bb))
3093 return 1;
3095 else if (fmt[i] == 'E')
3096 for (j = 0; j < XVECLEN (x, i); j++)
3097 if (expr_killed_p (XVECEXP (x, i, j), bb))
3098 return 1;
3101 return 0;
3104 /* Compute the set of available expressions killed in each basic block. */
3106 static void
3107 compute_ae_kill (sbitmap *ae_gen, sbitmap *ae_kill,
3108 struct hash_table *expr_hash_table)
3110 basic_block bb;
3111 unsigned int i;
3112 struct expr *expr;
3114 FOR_EACH_BB (bb)
3115 for (i = 0; i < expr_hash_table->size; i++)
3116 for (expr = expr_hash_table->table[i]; expr; expr = expr->next_same_hash)
3118 /* Skip EXPR if generated in this block. */
3119 if (TEST_BIT (ae_gen[bb->index], expr->bitmap_index))
3120 continue;
3122 if (expr_killed_p (expr->expr, bb))
3123 SET_BIT (ae_kill[bb->index], expr->bitmap_index);
3127 /* Actually perform the Classic GCSE optimizations. */
3129 /* Return nonzero if occurrence OCCR of expression EXPR reaches block BB.
3131 CHECK_SELF_LOOP is nonzero if we should consider a block reaching itself
3132 as a positive reach. We want to do this when there are two computations
3133 of the expression in the block.
3135 VISITED is a pointer to a working buffer for tracking which BB's have
3136 been visited. It is NULL for the top-level call.
3138 We treat reaching expressions that go through blocks containing the same
3139 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3140 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3141 2 as not reaching. The intent is to improve the probability of finding
3142 only one reaching expression and to reduce register lifetimes by picking
3143 the closest such expression. */
3145 static int
3146 expr_reaches_here_p_work (struct occr *occr, struct expr *expr,
3147 basic_block bb, int check_self_loop, char *visited)
3149 edge pred;
3151 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
3153 basic_block pred_bb = pred->src;
3155 if (visited[pred_bb->index])
3156 /* This predecessor has already been visited. Nothing to do. */
3158 else if (pred_bb == bb)
3160 /* BB loops on itself. */
3161 if (check_self_loop
3162 && TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index)
3163 && BLOCK_NUM (occr->insn) == pred_bb->index)
3164 return 1;
3166 visited[pred_bb->index] = 1;
3169 /* Ignore this predecessor if it kills the expression. */
3170 else if (TEST_BIT (ae_kill[pred_bb->index], expr->bitmap_index))
3171 visited[pred_bb->index] = 1;
3173 /* Does this predecessor generate this expression? */
3174 else if (TEST_BIT (ae_gen[pred_bb->index], expr->bitmap_index))
3176 /* Is this the occurrence we're looking for?
3177 Note that there's only one generating occurrence per block
3178 so we just need to check the block number. */
3179 if (BLOCK_NUM (occr->insn) == pred_bb->index)
3180 return 1;
3182 visited[pred_bb->index] = 1;
3185 /* Neither gen nor kill. */
3186 else
3188 visited[pred_bb->index] = 1;
3189 if (expr_reaches_here_p_work (occr, expr, pred_bb, check_self_loop,
3190 visited))
3192 return 1;
3196 /* All paths have been checked. */
3197 return 0;
3200 /* This wrapper for expr_reaches_here_p_work() is to ensure that any
3201 memory allocated for that function is returned. */
3203 static int
3204 expr_reaches_here_p (struct occr *occr, struct expr *expr, basic_block bb,
3205 int check_self_loop)
3207 int rval;
3208 char *visited = xcalloc (last_basic_block, 1);
3210 rval = expr_reaches_here_p_work (occr, expr, bb, check_self_loop, visited);
3212 free (visited);
3213 return rval;
3216 /* Return the instruction that computes EXPR that reaches INSN's basic block.
3217 If there is more than one such instruction, return NULL.
3219 Called only by handle_avail_expr. */
3221 static rtx
3222 computing_insn (struct expr *expr, rtx insn)
3224 basic_block bb = BLOCK_FOR_INSN (insn);
3226 if (expr->avail_occr->next == NULL)
3228 if (BLOCK_FOR_INSN (expr->avail_occr->insn) == bb)
3229 /* The available expression is actually itself
3230 (i.e. a loop in the flow graph) so do nothing. */
3231 return NULL;
3233 /* (FIXME) Case that we found a pattern that was created by
3234 a substitution that took place. */
3235 return expr->avail_occr->insn;
3237 else
3239 /* Pattern is computed more than once.
3240 Search backwards from this insn to see how many of these
3241 computations actually reach this insn. */
3242 struct occr *occr;
3243 rtx insn_computes_expr = NULL;
3244 int can_reach = 0;
3246 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
3248 if (BLOCK_FOR_INSN (occr->insn) == bb)
3250 /* The expression is generated in this block.
3251 The only time we care about this is when the expression
3252 is generated later in the block [and thus there's a loop].
3253 We let the normal cse pass handle the other cases. */
3254 if (INSN_CUID (insn) < INSN_CUID (occr->insn)
3255 && expr_reaches_here_p (occr, expr, bb, 1))
3257 can_reach++;
3258 if (can_reach > 1)
3259 return NULL;
3261 insn_computes_expr = occr->insn;
3264 else if (expr_reaches_here_p (occr, expr, bb, 0))
3266 can_reach++;
3267 if (can_reach > 1)
3268 return NULL;
3270 insn_computes_expr = occr->insn;
3274 if (insn_computes_expr == NULL)
3275 abort ();
3277 return insn_computes_expr;
3281 /* Return nonzero if the definition in DEF_INSN can reach INSN.
3282 Only called by can_disregard_other_sets. */
3284 static int
3285 def_reaches_here_p (rtx insn, rtx def_insn)
3287 rtx reg;
3289 if (TEST_BIT (reaching_defs[BLOCK_NUM (insn)], INSN_CUID (def_insn)))
3290 return 1;
3292 if (BLOCK_NUM (insn) == BLOCK_NUM (def_insn))
3294 if (INSN_CUID (def_insn) < INSN_CUID (insn))
3296 if (GET_CODE (PATTERN (def_insn)) == PARALLEL)
3297 return 1;
3298 else if (GET_CODE (PATTERN (def_insn)) == CLOBBER)
3299 reg = XEXP (PATTERN (def_insn), 0);
3300 else if (GET_CODE (PATTERN (def_insn)) == SET)
3301 reg = SET_DEST (PATTERN (def_insn));
3302 else
3303 abort ();
3305 return ! reg_set_between_p (reg, NEXT_INSN (def_insn), insn);
3307 else
3308 return 0;
3311 return 0;
3314 /* Return nonzero if *ADDR_THIS_REG can only have one value at INSN. The
3315 value returned is the number of definitions that reach INSN. Returning a
3316 value of zero means that [maybe] more than one definition reaches INSN and
3317 the caller can't perform whatever optimization it is trying. i.e. it is
3318 always safe to return zero. */
3320 static int
3321 can_disregard_other_sets (struct reg_set **addr_this_reg, rtx insn, int for_combine)
3323 int number_of_reaching_defs = 0;
3324 struct reg_set *this_reg;
3326 for (this_reg = *addr_this_reg; this_reg != 0; this_reg = this_reg->next)
3327 if (def_reaches_here_p (insn, this_reg->insn))
3329 number_of_reaching_defs++;
3330 /* Ignore parallels for now. */
3331 if (GET_CODE (PATTERN (this_reg->insn)) == PARALLEL)
3332 return 0;
3334 if (!for_combine
3335 && (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER
3336 || ! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
3337 SET_SRC (PATTERN (insn)))))
3338 /* A setting of the reg to a different value reaches INSN. */
3339 return 0;
3341 if (number_of_reaching_defs > 1)
3343 /* If in this setting the value the register is being set to is
3344 equal to the previous value the register was set to and this
3345 setting reaches the insn we are trying to do the substitution
3346 on then we are ok. */
3347 if (GET_CODE (PATTERN (this_reg->insn)) == CLOBBER)
3348 return 0;
3349 else if (! rtx_equal_p (SET_SRC (PATTERN (this_reg->insn)),
3350 SET_SRC (PATTERN (insn))))
3351 return 0;
3354 *addr_this_reg = this_reg;
3357 return number_of_reaching_defs;
3360 /* Expression computed by insn is available and the substitution is legal,
3361 so try to perform the substitution.
3363 The result is nonzero if any changes were made. */
3365 static int
3366 handle_avail_expr (rtx insn, struct expr *expr)
3368 rtx pat, insn_computes_expr, expr_set;
3369 rtx to;
3370 struct reg_set *this_reg;
3371 int found_setting, use_src;
3372 int changed = 0;
3374 /* We only handle the case where one computation of the expression
3375 reaches this instruction. */
3376 insn_computes_expr = computing_insn (expr, insn);
3377 if (insn_computes_expr == NULL)
3378 return 0;
3379 expr_set = single_set (insn_computes_expr);
3380 if (!expr_set)
3381 abort ();
3383 found_setting = 0;
3384 use_src = 0;
3386 /* At this point we know only one computation of EXPR outside of this
3387 block reaches this insn. Now try to find a register that the
3388 expression is computed into. */
3389 if (GET_CODE (SET_SRC (expr_set)) == REG)
3391 /* This is the case when the available expression that reaches
3392 here has already been handled as an available expression. */
3393 unsigned int regnum_for_replacing
3394 = REGNO (SET_SRC (expr_set));
3396 /* If the register was created by GCSE we can't use `reg_set_table',
3397 however we know it's set only once. */
3398 if (regnum_for_replacing >= max_gcse_regno
3399 /* If the register the expression is computed into is set only once,
3400 or only one set reaches this insn, we can use it. */
3401 || (((this_reg = reg_set_table[regnum_for_replacing]),
3402 this_reg->next == NULL)
3403 || can_disregard_other_sets (&this_reg, insn, 0)))
3405 use_src = 1;
3406 found_setting = 1;
3410 if (!found_setting)
3412 unsigned int regnum_for_replacing
3413 = REGNO (SET_DEST (expr_set));
3415 /* This shouldn't happen. */
3416 if (regnum_for_replacing >= max_gcse_regno)
3417 abort ();
3419 this_reg = reg_set_table[regnum_for_replacing];
3421 /* If the register the expression is computed into is set only once,
3422 or only one set reaches this insn, use it. */
3423 if (this_reg->next == NULL
3424 || can_disregard_other_sets (&this_reg, insn, 0))
3425 found_setting = 1;
3428 if (found_setting)
3430 pat = PATTERN (insn);
3431 if (use_src)
3432 to = SET_SRC (expr_set);
3433 else
3434 to = SET_DEST (expr_set);
3435 changed = validate_change (insn, &SET_SRC (pat), to, 0);
3437 /* We should be able to ignore the return code from validate_change but
3438 to play it safe we check. */
3439 if (changed)
3441 gcse_subst_count++;
3442 if (gcse_file != NULL)
3444 fprintf (gcse_file, "GCSE: Replacing the source in insn %d with",
3445 INSN_UID (insn));
3446 fprintf (gcse_file, " reg %d %s insn %d\n",
3447 REGNO (to), use_src ? "from" : "set in",
3448 INSN_UID (insn_computes_expr));
3453 /* The register that the expr is computed into is set more than once. */
3454 else if (1 /*expensive_op(this_pattrn->op) && do_expensive_gcse)*/)
3456 /* Insert an insn after insnx that copies the reg set in insnx
3457 into a new pseudo register call this new register REGN.
3458 From insnb until end of basic block or until REGB is set
3459 replace all uses of REGB with REGN. */
3460 rtx new_insn;
3462 to = gen_reg_rtx (GET_MODE (SET_DEST (expr_set)));
3464 /* Generate the new insn. */
3465 /* ??? If the change fails, we return 0, even though we created
3466 an insn. I think this is ok. */
3467 new_insn
3468 = emit_insn_after (gen_rtx_SET (VOIDmode, to,
3469 SET_DEST (expr_set)),
3470 insn_computes_expr);
3472 /* Keep register set table up to date. */
3473 record_one_set (REGNO (to), new_insn);
3475 gcse_create_count++;
3476 if (gcse_file != NULL)
3478 fprintf (gcse_file, "GCSE: Creating insn %d to copy value of reg %d",
3479 INSN_UID (NEXT_INSN (insn_computes_expr)),
3480 REGNO (SET_SRC (PATTERN (NEXT_INSN (insn_computes_expr)))));
3481 fprintf (gcse_file, ", computed in insn %d,\n",
3482 INSN_UID (insn_computes_expr));
3483 fprintf (gcse_file, " into newly allocated reg %d\n",
3484 REGNO (to));
3487 pat = PATTERN (insn);
3489 /* Do register replacement for INSN. */
3490 changed = validate_change (insn, &SET_SRC (pat),
3491 SET_DEST (PATTERN
3492 (NEXT_INSN (insn_computes_expr))),
3495 /* We should be able to ignore the return code from validate_change but
3496 to play it safe we check. */
3497 if (changed)
3499 gcse_subst_count++;
3500 if (gcse_file != NULL)
3502 fprintf (gcse_file,
3503 "GCSE: Replacing the source in insn %d with reg %d ",
3504 INSN_UID (insn),
3505 REGNO (SET_DEST (PATTERN (NEXT_INSN
3506 (insn_computes_expr)))));
3507 fprintf (gcse_file, "set in insn %d\n",
3508 INSN_UID (insn_computes_expr));
3513 return changed;
3516 /* Perform classic GCSE. This is called by one_classic_gcse_pass after all
3517 the dataflow analysis has been done.
3519 The result is nonzero if a change was made. */
3521 static int
3522 classic_gcse (void)
3524 int changed;
3525 rtx insn;
3526 basic_block bb;
3528 /* Note we start at block 1. */
3530 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
3531 return 0;
3533 changed = 0;
3534 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
3536 /* Reset tables used to keep track of what's still valid [since the
3537 start of the block]. */
3538 reset_opr_set_tables ();
3540 for (insn = bb->head;
3541 insn != NULL && insn != NEXT_INSN (bb->end);
3542 insn = NEXT_INSN (insn))
3544 /* Is insn of form (set (pseudo-reg) ...)? */
3545 if (GET_CODE (insn) == INSN
3546 && GET_CODE (PATTERN (insn)) == SET
3547 && GET_CODE (SET_DEST (PATTERN (insn))) == REG
3548 && REGNO (SET_DEST (PATTERN (insn))) >= FIRST_PSEUDO_REGISTER)
3550 rtx pat = PATTERN (insn);
3551 rtx src = SET_SRC (pat);
3552 struct expr *expr;
3554 if (want_to_gcse_p (src)
3555 /* Is the expression recorded? */
3556 && ((expr = lookup_expr (src, &expr_hash_table)) != NULL)
3557 /* Is the expression available [at the start of the
3558 block]? */
3559 && TEST_BIT (ae_in[bb->index], expr->bitmap_index)
3560 /* Are the operands unchanged since the start of the
3561 block? */
3562 && oprs_not_set_p (src, insn))
3563 changed |= handle_avail_expr (insn, expr);
3566 /* Keep track of everything modified by this insn. */
3567 /* ??? Need to be careful w.r.t. mods done to INSN. */
3568 if (INSN_P (insn))
3569 mark_oprs_set (insn);
3573 return changed;
3576 /* Top level routine to perform one classic GCSE pass.
3578 Return nonzero if a change was made. */
3580 static int
3581 one_classic_gcse_pass (int pass)
3583 int changed = 0;
3585 gcse_subst_count = 0;
3586 gcse_create_count = 0;
3588 alloc_hash_table (max_cuid, &expr_hash_table, 0);
3589 alloc_rd_mem (last_basic_block, max_cuid);
3590 compute_hash_table (&expr_hash_table);
3591 if (gcse_file)
3592 dump_hash_table (gcse_file, "Expression", &expr_hash_table);
3594 if (expr_hash_table.n_elems > 0)
3596 compute_kill_rd ();
3597 compute_rd ();
3598 alloc_avail_expr_mem (last_basic_block, expr_hash_table.n_elems);
3599 compute_ae_gen (&expr_hash_table);
3600 compute_ae_kill (ae_gen, ae_kill, &expr_hash_table);
3601 compute_available (ae_gen, ae_kill, ae_out, ae_in);
3602 changed = classic_gcse ();
3603 free_avail_expr_mem ();
3606 free_rd_mem ();
3607 free_hash_table (&expr_hash_table);
3609 if (gcse_file)
3611 fprintf (gcse_file, "\n");
3612 fprintf (gcse_file, "GCSE of %s, pass %d: %d bytes needed, %d substs,",
3613 current_function_name, pass, bytes_used, gcse_subst_count);
3614 fprintf (gcse_file, "%d insns created\n", gcse_create_count);
3617 return changed;
3620 /* Compute copy/constant propagation working variables. */
3622 /* Local properties of assignments. */
3623 static sbitmap *cprop_pavloc;
3624 static sbitmap *cprop_absaltered;
3626 /* Global properties of assignments (computed from the local properties). */
3627 static sbitmap *cprop_avin;
3628 static sbitmap *cprop_avout;
3630 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
3631 basic blocks. N_SETS is the number of sets. */
3633 static void
3634 alloc_cprop_mem (int n_blocks, int n_sets)
3636 cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
3637 cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
3639 cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
3640 cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
3643 /* Free vars used by copy/const propagation. */
3645 static void
3646 free_cprop_mem (void)
3648 sbitmap_vector_free (cprop_pavloc);
3649 sbitmap_vector_free (cprop_absaltered);
3650 sbitmap_vector_free (cprop_avin);
3651 sbitmap_vector_free (cprop_avout);
3654 /* For each block, compute whether X is transparent. X is either an
3655 expression or an assignment [though we don't care which, for this context
3656 an assignment is treated as an expression]. For each block where an
3657 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
3658 bit in BMAP. */
3660 static void
3661 compute_transp (rtx x, int indx, sbitmap *bmap, int set_p)
3663 int i, j;
3664 basic_block bb;
3665 enum rtx_code code;
3666 reg_set *r;
3667 const char *fmt;
3669 /* repeat is used to turn tail-recursion into iteration since GCC
3670 can't do it when there's no return value. */
3671 repeat:
3673 if (x == 0)
3674 return;
3676 code = GET_CODE (x);
3677 switch (code)
3679 case REG:
3680 if (set_p)
3682 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
3684 FOR_EACH_BB (bb)
3685 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
3686 SET_BIT (bmap[bb->index], indx);
3688 else
3690 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
3691 SET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
3694 else
3696 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
3698 FOR_EACH_BB (bb)
3699 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
3700 RESET_BIT (bmap[bb->index], indx);
3702 else
3704 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
3705 RESET_BIT (bmap[BLOCK_NUM (r->insn)], indx);
3709 return;
3711 case MEM:
3712 FOR_EACH_BB (bb)
3714 rtx list_entry = canon_modify_mem_list[bb->index];
3716 while (list_entry)
3718 rtx dest, dest_addr;
3720 if (GET_CODE (XEXP (list_entry, 0)) == CALL_INSN)
3722 if (set_p)
3723 SET_BIT (bmap[bb->index], indx);
3724 else
3725 RESET_BIT (bmap[bb->index], indx);
3726 break;
3728 /* LIST_ENTRY must be an INSN of some kind that sets memory.
3729 Examine each hunk of memory that is modified. */
3731 dest = XEXP (list_entry, 0);
3732 list_entry = XEXP (list_entry, 1);
3733 dest_addr = XEXP (list_entry, 0);
3735 if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
3736 x, rtx_addr_varies_p))
3738 if (set_p)
3739 SET_BIT (bmap[bb->index], indx);
3740 else
3741 RESET_BIT (bmap[bb->index], indx);
3742 break;
3744 list_entry = XEXP (list_entry, 1);
3748 x = XEXP (x, 0);
3749 goto repeat;
3751 case PC:
3752 case CC0: /*FIXME*/
3753 case CONST:
3754 case CONST_INT:
3755 case CONST_DOUBLE:
3756 case CONST_VECTOR:
3757 case SYMBOL_REF:
3758 case LABEL_REF:
3759 case ADDR_VEC:
3760 case ADDR_DIFF_VEC:
3761 return;
3763 default:
3764 break;
3767 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3769 if (fmt[i] == 'e')
3771 /* If we are about to do the last recursive call
3772 needed at this level, change it into iteration.
3773 This function is called enough to be worth it. */
3774 if (i == 0)
3776 x = XEXP (x, i);
3777 goto repeat;
3780 compute_transp (XEXP (x, i), indx, bmap, set_p);
3782 else if (fmt[i] == 'E')
3783 for (j = 0; j < XVECLEN (x, i); j++)
3784 compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
3788 /* Top level routine to do the dataflow analysis needed by copy/const
3789 propagation. */
3791 static void
3792 compute_cprop_data (void)
3794 compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, &set_hash_table);
3795 compute_available (cprop_pavloc, cprop_absaltered,
3796 cprop_avout, cprop_avin);
3799 /* Copy/constant propagation. */
3801 /* Maximum number of register uses in an insn that we handle. */
3802 #define MAX_USES 8
3804 /* Table of uses found in an insn.
3805 Allocated statically to avoid alloc/free complexity and overhead. */
3806 static struct reg_use reg_use_table[MAX_USES];
3808 /* Index into `reg_use_table' while building it. */
3809 static int reg_use_count;
3811 /* Set up a list of register numbers used in INSN. The found uses are stored
3812 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
3813 and contains the number of uses in the table upon exit.
3815 ??? If a register appears multiple times we will record it multiple times.
3816 This doesn't hurt anything but it will slow things down. */
3818 static void
3819 find_used_regs (rtx *xptr, void *data ATTRIBUTE_UNUSED)
3821 int i, j;
3822 enum rtx_code code;
3823 const char *fmt;
3824 rtx x = *xptr;
3826 /* repeat is used to turn tail-recursion into iteration since GCC
3827 can't do it when there's no return value. */
3828 repeat:
3829 if (x == 0)
3830 return;
3832 code = GET_CODE (x);
3833 if (REG_P (x))
3835 if (reg_use_count == MAX_USES)
3836 return;
3838 reg_use_table[reg_use_count].reg_rtx = x;
3839 reg_use_count++;
3842 /* Recursively scan the operands of this expression. */
3844 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
3846 if (fmt[i] == 'e')
3848 /* If we are about to do the last recursive call
3849 needed at this level, change it into iteration.
3850 This function is called enough to be worth it. */
3851 if (i == 0)
3853 x = XEXP (x, 0);
3854 goto repeat;
3857 find_used_regs (&XEXP (x, i), data);
3859 else if (fmt[i] == 'E')
3860 for (j = 0; j < XVECLEN (x, i); j++)
3861 find_used_regs (&XVECEXP (x, i, j), data);
3865 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
3866 Returns nonzero is successful. */
3868 static int
3869 try_replace_reg (rtx from, rtx to, rtx insn)
3871 rtx note = find_reg_equal_equiv_note (insn);
3872 rtx src = 0;
3873 int success = 0;
3874 rtx set = single_set (insn);
3876 validate_replace_src_group (from, to, insn);
3877 if (num_changes_pending () && apply_change_group ())
3878 success = 1;
3880 /* Try to simplify SET_SRC if we have substituted a constant. */
3881 if (success && set && CONSTANT_P (to))
3883 src = simplify_rtx (SET_SRC (set));
3885 if (src)
3886 validate_change (insn, &SET_SRC (set), src, 0);
3889 /* If there is already a NOTE, update the expression in it with our
3890 replacement. */
3891 if (note != 0)
3892 XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), from, to);
3894 if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
3896 /* If above failed and this is a single set, try to simplify the source of
3897 the set given our substitution. We could perhaps try this for multiple
3898 SETs, but it probably won't buy us anything. */
3899 src = simplify_replace_rtx (SET_SRC (set), from, to);
3901 if (!rtx_equal_p (src, SET_SRC (set))
3902 && validate_change (insn, &SET_SRC (set), src, 0))
3903 success = 1;
3905 /* If we've failed to do replacement, have a single SET, don't already
3906 have a note, and have no special SET, add a REG_EQUAL note to not
3907 lose information. */
3908 if (!success && note == 0 && set != 0
3909 && GET_CODE (XEXP (set, 0)) != ZERO_EXTRACT
3910 && GET_CODE (XEXP (set, 0)) != SIGN_EXTRACT)
3911 note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
3914 /* REG_EQUAL may get simplified into register.
3915 We don't allow that. Remove that note. This code ought
3916 not to happen, because previous code ought to synthesize
3917 reg-reg move, but be on the safe side. */
3918 if (note && REG_P (XEXP (note, 0)))
3919 remove_note (insn, note);
3921 return success;
3924 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
3925 NULL no such set is found. */
3927 static struct expr *
3928 find_avail_set (int regno, rtx insn)
3930 /* SET1 contains the last set found that can be returned to the caller for
3931 use in a substitution. */
3932 struct expr *set1 = 0;
3934 /* Loops are not possible here. To get a loop we would need two sets
3935 available at the start of the block containing INSN. ie we would
3936 need two sets like this available at the start of the block:
3938 (set (reg X) (reg Y))
3939 (set (reg Y) (reg X))
3941 This can not happen since the set of (reg Y) would have killed the
3942 set of (reg X) making it unavailable at the start of this block. */
3943 while (1)
3945 rtx src;
3946 struct expr *set = lookup_set (regno, &set_hash_table);
3948 /* Find a set that is available at the start of the block
3949 which contains INSN. */
3950 while (set)
3952 if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
3953 break;
3954 set = next_set (regno, set);
3957 /* If no available set was found we've reached the end of the
3958 (possibly empty) copy chain. */
3959 if (set == 0)
3960 break;
3962 if (GET_CODE (set->expr) != SET)
3963 abort ();
3965 src = SET_SRC (set->expr);
3967 /* We know the set is available.
3968 Now check that SRC is ANTLOC (i.e. none of the source operands
3969 have changed since the start of the block).
3971 If the source operand changed, we may still use it for the next
3972 iteration of this loop, but we may not use it for substitutions. */
3974 if (gcse_constant_p (src) || oprs_not_set_p (src, insn))
3975 set1 = set;
3977 /* If the source of the set is anything except a register, then
3978 we have reached the end of the copy chain. */
3979 if (GET_CODE (src) != REG)
3980 break;
3982 /* Follow the copy chain, ie start another iteration of the loop
3983 and see if we have an available copy into SRC. */
3984 regno = REGNO (src);
3987 /* SET1 holds the last set that was available and anticipatable at
3988 INSN. */
3989 return set1;
3992 /* Subroutine of cprop_insn that tries to propagate constants into
3993 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
3994 it is the instruction that immediately precedes JUMP, and must be a
3995 single SET of a register. FROM is what we will try to replace,
3996 SRC is the constant we will try to substitute for it. Returns nonzero
3997 if a change was made. */
3999 static int
4000 cprop_jump (basic_block bb, rtx setcc, rtx jump, rtx from, rtx src)
4002 rtx new, set_src, note_src;
4003 rtx set = pc_set (jump);
4004 rtx note = find_reg_equal_equiv_note (jump);
4006 if (note)
4008 note_src = XEXP (note, 0);
4009 if (GET_CODE (note_src) == EXPR_LIST)
4010 note_src = NULL_RTX;
4012 else note_src = NULL_RTX;
4014 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
4015 set_src = note_src ? note_src : SET_SRC (set);
4017 /* First substitute the SETCC condition into the JUMP instruction,
4018 then substitute that given values into this expanded JUMP. */
4019 if (setcc != NULL_RTX
4020 && !modified_between_p (from, setcc, jump)
4021 && !modified_between_p (src, setcc, jump))
4023 rtx setcc_src;
4024 rtx setcc_set = single_set (setcc);
4025 rtx setcc_note = find_reg_equal_equiv_note (setcc);
4026 setcc_src = (setcc_note && GET_CODE (XEXP (setcc_note, 0)) != EXPR_LIST)
4027 ? XEXP (setcc_note, 0) : SET_SRC (setcc_set);
4028 set_src = simplify_replace_rtx (set_src, SET_DEST (setcc_set),
4029 setcc_src);
4031 else
4032 setcc = NULL_RTX;
4034 new = simplify_replace_rtx (set_src, from, src);
4036 /* If no simplification can be made, then try the next register. */
4037 if (rtx_equal_p (new, SET_SRC (set)))
4038 return 0;
4040 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
4041 if (new == pc_rtx)
4042 delete_insn (jump);
4043 else
4045 /* Ensure the value computed inside the jump insn to be equivalent
4046 to one computed by setcc. */
4047 if (setcc && modified_in_p (new, setcc))
4048 return 0;
4049 if (! validate_change (jump, &SET_SRC (set), new, 0))
4051 /* When (some) constants are not valid in a comparison, and there
4052 are two registers to be replaced by constants before the entire
4053 comparison can be folded into a constant, we need to keep
4054 intermediate information in REG_EQUAL notes. For targets with
4055 separate compare insns, such notes are added by try_replace_reg.
4056 When we have a combined compare-and-branch instruction, however,
4057 we need to attach a note to the branch itself to make this
4058 optimization work. */
4060 if (!rtx_equal_p (new, note_src))
4061 set_unique_reg_note (jump, REG_EQUAL, copy_rtx (new));
4062 return 0;
4065 /* Remove REG_EQUAL note after simplification. */
4066 if (note_src)
4067 remove_note (jump, note);
4069 /* If this has turned into an unconditional jump,
4070 then put a barrier after it so that the unreachable
4071 code will be deleted. */
4072 if (GET_CODE (SET_SRC (set)) == LABEL_REF)
4073 emit_barrier_after (jump);
4076 #ifdef HAVE_cc0
4077 /* Delete the cc0 setter. */
4078 if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
4079 delete_insn (setcc);
4080 #endif
4082 run_jump_opt_after_gcse = 1;
4084 const_prop_count++;
4085 if (gcse_file != NULL)
4087 fprintf (gcse_file,
4088 "CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
4089 REGNO (from), INSN_UID (jump));
4090 print_rtl (gcse_file, src);
4091 fprintf (gcse_file, "\n");
4093 purge_dead_edges (bb);
4095 return 1;
4098 static bool
4099 constprop_register (rtx insn, rtx from, rtx to, int alter_jumps)
4101 rtx sset;
4103 /* Check for reg or cc0 setting instructions followed by
4104 conditional branch instructions first. */
4105 if (alter_jumps
4106 && (sset = single_set (insn)) != NULL
4107 && NEXT_INSN (insn)
4108 && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
4110 rtx dest = SET_DEST (sset);
4111 if ((REG_P (dest) || CC0_P (dest))
4112 && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to))
4113 return 1;
4116 /* Handle normal insns next. */
4117 if (GET_CODE (insn) == INSN
4118 && try_replace_reg (from, to, insn))
4119 return 1;
4121 /* Try to propagate a CONST_INT into a conditional jump.
4122 We're pretty specific about what we will handle in this
4123 code, we can extend this as necessary over time.
4125 Right now the insn in question must look like
4126 (set (pc) (if_then_else ...)) */
4127 else if (alter_jumps && any_condjump_p (insn) && onlyjump_p (insn))
4128 return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to);
4129 return 0;
4132 /* Perform constant and copy propagation on INSN.
4133 The result is nonzero if a change was made. */
4135 static int
4136 cprop_insn (rtx insn, int alter_jumps)
4138 struct reg_use *reg_used;
4139 int changed = 0;
4140 rtx note;
4142 if (!INSN_P (insn))
4143 return 0;
4145 reg_use_count = 0;
4146 note_uses (&PATTERN (insn), find_used_regs, NULL);
4148 note = find_reg_equal_equiv_note (insn);
4150 /* We may win even when propagating constants into notes. */
4151 if (note)
4152 find_used_regs (&XEXP (note, 0), NULL);
4154 for (reg_used = &reg_use_table[0]; reg_use_count > 0;
4155 reg_used++, reg_use_count--)
4157 unsigned int regno = REGNO (reg_used->reg_rtx);
4158 rtx pat, src;
4159 struct expr *set;
4161 /* Ignore registers created by GCSE.
4162 We do this because ... */
4163 if (regno >= max_gcse_regno)
4164 continue;
4166 /* If the register has already been set in this block, there's
4167 nothing we can do. */
4168 if (! oprs_not_set_p (reg_used->reg_rtx, insn))
4169 continue;
4171 /* Find an assignment that sets reg_used and is available
4172 at the start of the block. */
4173 set = find_avail_set (regno, insn);
4174 if (! set)
4175 continue;
4177 pat = set->expr;
4178 /* ??? We might be able to handle PARALLELs. Later. */
4179 if (GET_CODE (pat) != SET)
4180 abort ();
4182 src = SET_SRC (pat);
4184 /* Constant propagation. */
4185 if (gcse_constant_p (src))
4187 if (constprop_register (insn, reg_used->reg_rtx, src, alter_jumps))
4189 changed = 1;
4190 const_prop_count++;
4191 if (gcse_file != NULL)
4193 fprintf (gcse_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
4194 fprintf (gcse_file, "insn %d with constant ", INSN_UID (insn));
4195 print_rtl (gcse_file, src);
4196 fprintf (gcse_file, "\n");
4198 if (INSN_DELETED_P (insn))
4199 return 1;
4202 else if (GET_CODE (src) == REG
4203 && REGNO (src) >= FIRST_PSEUDO_REGISTER
4204 && REGNO (src) != regno)
4206 if (try_replace_reg (reg_used->reg_rtx, src, insn))
4208 changed = 1;
4209 copy_prop_count++;
4210 if (gcse_file != NULL)
4212 fprintf (gcse_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
4213 regno, INSN_UID (insn));
4214 fprintf (gcse_file, " with reg %d\n", REGNO (src));
4217 /* The original insn setting reg_used may or may not now be
4218 deletable. We leave the deletion to flow. */
4219 /* FIXME: If it turns out that the insn isn't deletable,
4220 then we may have unnecessarily extended register lifetimes
4221 and made things worse. */
4226 return changed;
4229 /* Like find_used_regs, but avoid recording uses that appear in
4230 input-output contexts such as zero_extract or pre_dec. This
4231 restricts the cases we consider to those for which local cprop
4232 can legitimately make replacements. */
4234 static void
4235 local_cprop_find_used_regs (rtx *xptr, void *data)
4237 rtx x = *xptr;
4239 if (x == 0)
4240 return;
4242 switch (GET_CODE (x))
4244 case ZERO_EXTRACT:
4245 case SIGN_EXTRACT:
4246 case STRICT_LOW_PART:
4247 return;
4249 case PRE_DEC:
4250 case PRE_INC:
4251 case POST_DEC:
4252 case POST_INC:
4253 case PRE_MODIFY:
4254 case POST_MODIFY:
4255 /* Can only legitimately appear this early in the context of
4256 stack pushes for function arguments, but handle all of the
4257 codes nonetheless. */
4258 return;
4260 case SUBREG:
4261 /* Setting a subreg of a register larger than word_mode leaves
4262 the non-written words unchanged. */
4263 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
4264 return;
4265 break;
4267 default:
4268 break;
4271 find_used_regs (xptr, data);
4274 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4275 their REG_EQUAL notes need updating. */
4277 static bool
4278 do_local_cprop (rtx x, rtx insn, int alter_jumps, rtx *libcall_sp)
4280 rtx newreg = NULL, newcnst = NULL;
4282 /* Rule out USE instructions and ASM statements as we don't want to
4283 change the hard registers mentioned. */
4284 if (GET_CODE (x) == REG
4285 && (REGNO (x) >= FIRST_PSEUDO_REGISTER
4286 || (GET_CODE (PATTERN (insn)) != USE
4287 && asm_noperands (PATTERN (insn)) < 0)))
4289 cselib_val *val = cselib_lookup (x, GET_MODE (x), 0);
4290 struct elt_loc_list *l;
4292 if (!val)
4293 return false;
4294 for (l = val->locs; l; l = l->next)
4296 rtx this_rtx = l->loc;
4297 rtx note;
4299 if (l->in_libcall)
4300 continue;
4302 if (gcse_constant_p (this_rtx))
4303 newcnst = this_rtx;
4304 if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
4305 /* Don't copy propagate if it has attached REG_EQUIV note.
4306 At this point this only function parameters should have
4307 REG_EQUIV notes and if the argument slot is used somewhere
4308 explicitly, it means address of parameter has been taken,
4309 so we should not extend the lifetime of the pseudo. */
4310 && (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX))
4311 || GET_CODE (XEXP (note, 0)) != MEM))
4312 newreg = this_rtx;
4314 if (newcnst && constprop_register (insn, x, newcnst, alter_jumps))
4316 /* If we find a case where we can't fix the retval REG_EQUAL notes
4317 match the new register, we either have to abandon this replacement
4318 or fix delete_trivially_dead_insns to preserve the setting insn,
4319 or make it delete the REG_EUAQL note, and fix up all passes that
4320 require the REG_EQUAL note there. */
4321 if (!adjust_libcall_notes (x, newcnst, insn, libcall_sp))
4322 abort ();
4323 if (gcse_file != NULL)
4325 fprintf (gcse_file, "LOCAL CONST-PROP: Replacing reg %d in ",
4326 REGNO (x));
4327 fprintf (gcse_file, "insn %d with constant ",
4328 INSN_UID (insn));
4329 print_rtl (gcse_file, newcnst);
4330 fprintf (gcse_file, "\n");
4332 const_prop_count++;
4333 return true;
4335 else if (newreg && newreg != x && try_replace_reg (x, newreg, insn))
4337 adjust_libcall_notes (x, newreg, insn, libcall_sp);
4338 if (gcse_file != NULL)
4340 fprintf (gcse_file,
4341 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
4342 REGNO (x), INSN_UID (insn));
4343 fprintf (gcse_file, " with reg %d\n", REGNO (newreg));
4345 copy_prop_count++;
4346 return true;
4349 return false;
4352 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
4353 their REG_EQUAL notes need updating to reflect that OLDREG has been
4354 replaced with NEWVAL in INSN. Return true if all substitutions could
4355 be made. */
4356 static bool
4357 adjust_libcall_notes (rtx oldreg, rtx newval, rtx insn, rtx *libcall_sp)
4359 rtx end;
4361 while ((end = *libcall_sp++))
4363 rtx note = find_reg_equal_equiv_note (end);
4365 if (! note)
4366 continue;
4368 if (REG_P (newval))
4370 if (reg_set_between_p (newval, PREV_INSN (insn), end))
4374 note = find_reg_equal_equiv_note (end);
4375 if (! note)
4376 continue;
4377 if (reg_mentioned_p (newval, XEXP (note, 0)))
4378 return false;
4380 while ((end = *libcall_sp++));
4381 return true;
4384 XEXP (note, 0) = replace_rtx (XEXP (note, 0), oldreg, newval);
4385 insn = end;
4387 return true;
4390 #define MAX_NESTED_LIBCALLS 9
4392 static void
4393 local_cprop_pass (int alter_jumps)
4395 rtx insn;
4396 struct reg_use *reg_used;
4397 rtx libcall_stack[MAX_NESTED_LIBCALLS + 1], *libcall_sp;
4398 bool changed = false;
4400 cselib_init ();
4401 libcall_sp = &libcall_stack[MAX_NESTED_LIBCALLS];
4402 *libcall_sp = 0;
4403 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
4405 if (INSN_P (insn))
4407 rtx note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
4409 if (note)
4411 if (libcall_sp == libcall_stack)
4412 abort ();
4413 *--libcall_sp = XEXP (note, 0);
4415 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
4416 if (note)
4417 libcall_sp++;
4418 note = find_reg_equal_equiv_note (insn);
4421 reg_use_count = 0;
4422 note_uses (&PATTERN (insn), local_cprop_find_used_regs, NULL);
4423 if (note)
4424 local_cprop_find_used_regs (&XEXP (note, 0), NULL);
4426 for (reg_used = &reg_use_table[0]; reg_use_count > 0;
4427 reg_used++, reg_use_count--)
4428 if (do_local_cprop (reg_used->reg_rtx, insn, alter_jumps,
4429 libcall_sp))
4431 changed = true;
4432 break;
4434 if (INSN_DELETED_P (insn))
4435 break;
4437 while (reg_use_count);
4439 cselib_process_insn (insn);
4441 cselib_finish ();
4442 /* Global analysis may get into infinite loops for unreachable blocks. */
4443 if (changed && alter_jumps)
4445 delete_unreachable_blocks ();
4446 free_reg_set_mem ();
4447 alloc_reg_set_mem (max_reg_num ());
4448 compute_sets (get_insns ());
4452 /* Forward propagate copies. This includes copies and constants. Return
4453 nonzero if a change was made. */
4455 static int
4456 cprop (int alter_jumps)
4458 int changed;
4459 basic_block bb;
4460 rtx insn;
4462 /* Note we start at block 1. */
4463 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
4465 if (gcse_file != NULL)
4466 fprintf (gcse_file, "\n");
4467 return 0;
4470 changed = 0;
4471 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
4473 /* Reset tables used to keep track of what's still valid [since the
4474 start of the block]. */
4475 reset_opr_set_tables ();
4477 for (insn = bb->head;
4478 insn != NULL && insn != NEXT_INSN (bb->end);
4479 insn = NEXT_INSN (insn))
4480 if (INSN_P (insn))
4482 changed |= cprop_insn (insn, alter_jumps);
4484 /* Keep track of everything modified by this insn. */
4485 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
4486 call mark_oprs_set if we turned the insn into a NOTE. */
4487 if (GET_CODE (insn) != NOTE)
4488 mark_oprs_set (insn);
4492 if (gcse_file != NULL)
4493 fprintf (gcse_file, "\n");
4495 return changed;
4498 /* Similar to get_condition, only the resulting condition must be
4499 valid at JUMP, instead of at EARLIEST.
4501 This differs from noce_get_condition in ifcvt.c in that we prefer not to
4502 settle for the condition variable in the jump instruction being integral.
4503 We prefer to be able to record the value of a user variable, rather than
4504 the value of a temporary used in a condition. This could be solved by
4505 recording the value of *every* register scaned by canonicalize_condition,
4506 but this would require some code reorganization. */
4509 fis_get_condition (rtx jump)
4511 rtx cond, set, tmp, insn, earliest;
4512 bool reverse;
4514 if (! any_condjump_p (jump))
4515 return NULL_RTX;
4517 set = pc_set (jump);
4518 cond = XEXP (SET_SRC (set), 0);
4520 /* If this branches to JUMP_LABEL when the condition is false,
4521 reverse the condition. */
4522 reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
4523 && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
4525 /* Use canonicalize_condition to do the dirty work of manipulating
4526 MODE_CC values and COMPARE rtx codes. */
4527 tmp = canonicalize_condition (jump, cond, reverse, &earliest, NULL_RTX,
4528 false);
4529 if (!tmp)
4530 return NULL_RTX;
4532 /* Verify that the given condition is valid at JUMP by virtue of not
4533 having been modified since EARLIEST. */
4534 for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
4535 if (INSN_P (insn) && modified_in_p (tmp, insn))
4536 break;
4537 if (insn == jump)
4538 return tmp;
4540 /* The condition was modified. See if we can get a partial result
4541 that doesn't follow all the reversals. Perhaps combine can fold
4542 them together later. */
4543 tmp = XEXP (tmp, 0);
4544 if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
4545 return NULL_RTX;
4546 tmp = canonicalize_condition (jump, cond, reverse, &earliest, tmp,
4547 false);
4548 if (!tmp)
4549 return NULL_RTX;
4551 /* For sanity's sake, re-validate the new result. */
4552 for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
4553 if (INSN_P (insn) && modified_in_p (tmp, insn))
4554 return NULL_RTX;
4556 return tmp;
4559 /* Find the implicit sets of a function. An "implicit set" is a constraint
4560 on the value of a variable, implied by a conditional jump. For example,
4561 following "if (x == 2)", the then branch may be optimized as though the
4562 conditional performed an "explicit set", in this example, "x = 2". This
4563 function records the set patterns that are implicit at the start of each
4564 basic block. */
4566 static void
4567 find_implicit_sets (void)
4569 basic_block bb, dest;
4570 unsigned int count;
4571 rtx cond, new;
4573 count = 0;
4574 FOR_EACH_BB (bb)
4575 /* Check for more than one successor. */
4576 if (bb->succ && bb->succ->succ_next)
4578 cond = fis_get_condition (bb->end);
4580 if (cond
4581 && (GET_CODE (cond) == EQ || GET_CODE (cond) == NE)
4582 && GET_CODE (XEXP (cond, 0)) == REG
4583 && REGNO (XEXP (cond, 0)) >= FIRST_PSEUDO_REGISTER
4584 && gcse_constant_p (XEXP (cond, 1)))
4586 dest = GET_CODE (cond) == EQ ? BRANCH_EDGE (bb)->dest
4587 : FALLTHRU_EDGE (bb)->dest;
4589 if (dest && ! dest->pred->pred_next
4590 && dest != EXIT_BLOCK_PTR)
4592 new = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
4593 XEXP (cond, 1));
4594 implicit_sets[dest->index] = new;
4595 if (gcse_file)
4597 fprintf(gcse_file, "Implicit set of reg %d in ",
4598 REGNO (XEXP (cond, 0)));
4599 fprintf(gcse_file, "basic block %d\n", dest->index);
4601 count++;
4606 if (gcse_file)
4607 fprintf (gcse_file, "Found %d implicit sets\n", count);
4610 /* Perform one copy/constant propagation pass.
4611 PASS is the pass count. If CPROP_JUMPS is true, perform constant
4612 propagation into conditional jumps. If BYPASS_JUMPS is true,
4613 perform conditional jump bypassing optimizations. */
4615 static int
4616 one_cprop_pass (int pass, int cprop_jumps, int bypass_jumps)
4618 int changed = 0;
4620 const_prop_count = 0;
4621 copy_prop_count = 0;
4623 local_cprop_pass (cprop_jumps);
4625 /* Determine implicit sets. */
4626 implicit_sets = xcalloc (last_basic_block, sizeof (rtx));
4627 find_implicit_sets ();
4629 alloc_hash_table (max_cuid, &set_hash_table, 1);
4630 compute_hash_table (&set_hash_table);
4632 /* Free implicit_sets before peak usage. */
4633 free (implicit_sets);
4634 implicit_sets = NULL;
4636 if (gcse_file)
4637 dump_hash_table (gcse_file, "SET", &set_hash_table);
4638 if (set_hash_table.n_elems > 0)
4640 alloc_cprop_mem (last_basic_block, set_hash_table.n_elems);
4641 compute_cprop_data ();
4642 changed = cprop (cprop_jumps);
4643 if (bypass_jumps)
4644 changed |= bypass_conditional_jumps ();
4645 free_cprop_mem ();
4648 free_hash_table (&set_hash_table);
4650 if (gcse_file)
4652 fprintf (gcse_file, "CPROP of %s, pass %d: %d bytes needed, ",
4653 current_function_name, pass, bytes_used);
4654 fprintf (gcse_file, "%d const props, %d copy props\n\n",
4655 const_prop_count, copy_prop_count);
4657 /* Global analysis may get into infinite loops for unreachable blocks. */
4658 if (changed && cprop_jumps)
4659 delete_unreachable_blocks ();
4661 return changed;
4664 /* Bypass conditional jumps. */
4666 /* The value of last_basic_block at the beginning of the jump_bypass
4667 pass. The use of redirect_edge_and_branch_force may introduce new
4668 basic blocks, but the data flow analysis is only valid for basic
4669 block indices less than bypass_last_basic_block. */
4671 static int bypass_last_basic_block;
4673 /* Find a set of REGNO to a constant that is available at the end of basic
4674 block BB. Returns NULL if no such set is found. Based heavily upon
4675 find_avail_set. */
4677 static struct expr *
4678 find_bypass_set (int regno, int bb)
4680 struct expr *result = 0;
4682 for (;;)
4684 rtx src;
4685 struct expr *set = lookup_set (regno, &set_hash_table);
4687 while (set)
4689 if (TEST_BIT (cprop_avout[bb], set->bitmap_index))
4690 break;
4691 set = next_set (regno, set);
4694 if (set == 0)
4695 break;
4697 if (GET_CODE (set->expr) != SET)
4698 abort ();
4700 src = SET_SRC (set->expr);
4701 if (gcse_constant_p (src))
4702 result = set;
4704 if (GET_CODE (src) != REG)
4705 break;
4707 regno = REGNO (src);
4709 return result;
4713 /* Subroutine of bypass_block that checks whether a pseudo is killed by
4714 any of the instructions inserted on an edge. Jump bypassing places
4715 condition code setters on CFG edges using insert_insn_on_edge. This
4716 function is required to check that our data flow analysis is still
4717 valid prior to commit_edge_insertions. */
4719 static bool
4720 reg_killed_on_edge (rtx reg, edge e)
4722 rtx insn;
4724 for (insn = e->insns; insn; insn = NEXT_INSN (insn))
4725 if (INSN_P (insn) && reg_set_p (reg, insn))
4726 return true;
4728 return false;
4731 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
4732 basic block BB which has more than one predecessor. If not NULL, SETCC
4733 is the first instruction of BB, which is immediately followed by JUMP_INSN
4734 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
4735 Returns nonzero if a change was made.
4737 During the jump bypassing pass, we may place copies of SETCC instructions
4738 on CFG edges. The following routine must be careful to pay attention to
4739 these inserted insns when performing its transformations. */
4741 static int
4742 bypass_block (basic_block bb, rtx setcc, rtx jump)
4744 rtx insn, note;
4745 edge e, enext, edest;
4746 int i, change;
4747 int may_be_loop_header;
4749 insn = (setcc != NULL) ? setcc : jump;
4751 /* Determine set of register uses in INSN. */
4752 reg_use_count = 0;
4753 note_uses (&PATTERN (insn), find_used_regs, NULL);
4754 note = find_reg_equal_equiv_note (insn);
4755 if (note)
4756 find_used_regs (&XEXP (note, 0), NULL);
4758 may_be_loop_header = false;
4759 for (e = bb->pred; e; e = e->pred_next)
4760 if (e->flags & EDGE_DFS_BACK)
4762 may_be_loop_header = true;
4763 break;
4766 change = 0;
4767 for (e = bb->pred; e; e = enext)
4769 enext = e->pred_next;
4770 if (e->flags & EDGE_COMPLEX)
4771 continue;
4773 /* We can't redirect edges from new basic blocks. */
4774 if (e->src->index >= bypass_last_basic_block)
4775 continue;
4777 /* The irreducible loops created by redirecting of edges entering the
4778 loop from outside would decrease effectiveness of some of the following
4779 optimizations, so prevent this. */
4780 if (may_be_loop_header
4781 && !(e->flags & EDGE_DFS_BACK))
4782 continue;
4784 for (i = 0; i < reg_use_count; i++)
4786 struct reg_use *reg_used = &reg_use_table[i];
4787 unsigned int regno = REGNO (reg_used->reg_rtx);
4788 basic_block dest, old_dest;
4789 struct expr *set;
4790 rtx src, new;
4792 if (regno >= max_gcse_regno)
4793 continue;
4795 set = find_bypass_set (regno, e->src->index);
4797 if (! set)
4798 continue;
4800 /* Check the data flow is valid after edge insertions. */
4801 if (e->insns && reg_killed_on_edge (reg_used->reg_rtx, e))
4802 continue;
4804 src = SET_SRC (pc_set (jump));
4806 if (setcc != NULL)
4807 src = simplify_replace_rtx (src,
4808 SET_DEST (PATTERN (setcc)),
4809 SET_SRC (PATTERN (setcc)));
4811 new = simplify_replace_rtx (src, reg_used->reg_rtx,
4812 SET_SRC (set->expr));
4814 /* Jump bypassing may have already placed instructions on
4815 edges of the CFG. We can't bypass an outgoing edge that
4816 has instructions associated with it, as these insns won't
4817 get executed if the incoming edge is redirected. */
4819 if (new == pc_rtx)
4821 edest = FALLTHRU_EDGE (bb);
4822 dest = edest->insns ? NULL : edest->dest;
4824 else if (GET_CODE (new) == LABEL_REF)
4826 dest = BLOCK_FOR_INSN (XEXP (new, 0));
4827 /* Don't bypass edges containing instructions. */
4828 for (edest = bb->succ; edest; edest = edest->succ_next)
4829 if (edest->dest == dest && edest->insns)
4831 dest = NULL;
4832 break;
4835 else
4836 dest = NULL;
4838 old_dest = e->dest;
4839 if (dest != NULL
4840 && dest != old_dest
4841 && dest != EXIT_BLOCK_PTR)
4843 redirect_edge_and_branch_force (e, dest);
4845 /* Copy the register setter to the redirected edge.
4846 Don't copy CC0 setters, as CC0 is dead after jump. */
4847 if (setcc)
4849 rtx pat = PATTERN (setcc);
4850 if (!CC0_P (SET_DEST (pat)))
4851 insert_insn_on_edge (copy_insn (pat), e);
4854 if (gcse_file != NULL)
4856 fprintf (gcse_file, "JUMP-BYPASS: Proved reg %d in jump_insn %d equals constant ",
4857 regno, INSN_UID (jump));
4858 print_rtl (gcse_file, SET_SRC (set->expr));
4859 fprintf (gcse_file, "\nBypass edge from %d->%d to %d\n",
4860 e->src->index, old_dest->index, dest->index);
4862 change = 1;
4863 break;
4867 return change;
4870 /* Find basic blocks with more than one predecessor that only contain a
4871 single conditional jump. If the result of the comparison is known at
4872 compile-time from any incoming edge, redirect that edge to the
4873 appropriate target. Returns nonzero if a change was made.
4875 This function is now mis-named, because we also handle indirect jumps. */
4877 static int
4878 bypass_conditional_jumps (void)
4880 basic_block bb;
4881 int changed;
4882 rtx setcc;
4883 rtx insn;
4884 rtx dest;
4886 /* Note we start at block 1. */
4887 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
4888 return 0;
4890 bypass_last_basic_block = last_basic_block;
4891 mark_dfs_back_edges ();
4893 changed = 0;
4894 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb,
4895 EXIT_BLOCK_PTR, next_bb)
4897 /* Check for more than one predecessor. */
4898 if (bb->pred && bb->pred->pred_next)
4900 setcc = NULL_RTX;
4901 for (insn = bb->head;
4902 insn != NULL && insn != NEXT_INSN (bb->end);
4903 insn = NEXT_INSN (insn))
4904 if (GET_CODE (insn) == INSN)
4906 if (setcc)
4907 break;
4908 if (GET_CODE (PATTERN (insn)) != SET)
4909 break;
4911 dest = SET_DEST (PATTERN (insn));
4912 if (REG_P (dest) || CC0_P (dest))
4913 setcc = insn;
4914 else
4915 break;
4917 else if (GET_CODE (insn) == JUMP_INSN)
4919 if ((any_condjump_p (insn) || computed_jump_p (insn))
4920 && onlyjump_p (insn))
4921 changed |= bypass_block (bb, setcc, insn);
4922 break;
4924 else if (INSN_P (insn))
4925 break;
4929 /* If we bypassed any register setting insns, we inserted a
4930 copy on the redirected edge. These need to be committed. */
4931 if (changed)
4932 commit_edge_insertions();
4934 return changed;
4937 /* Compute PRE+LCM working variables. */
4939 /* Local properties of expressions. */
4940 /* Nonzero for expressions that are transparent in the block. */
4941 static sbitmap *transp;
4943 /* Nonzero for expressions that are transparent at the end of the block.
4944 This is only zero for expressions killed by abnormal critical edge
4945 created by a calls. */
4946 static sbitmap *transpout;
4948 /* Nonzero for expressions that are computed (available) in the block. */
4949 static sbitmap *comp;
4951 /* Nonzero for expressions that are locally anticipatable in the block. */
4952 static sbitmap *antloc;
4954 /* Nonzero for expressions where this block is an optimal computation
4955 point. */
4956 static sbitmap *pre_optimal;
4958 /* Nonzero for expressions which are redundant in a particular block. */
4959 static sbitmap *pre_redundant;
4961 /* Nonzero for expressions which should be inserted on a specific edge. */
4962 static sbitmap *pre_insert_map;
4964 /* Nonzero for expressions which should be deleted in a specific block. */
4965 static sbitmap *pre_delete_map;
4967 /* Contains the edge_list returned by pre_edge_lcm. */
4968 static struct edge_list *edge_list;
4970 /* Redundant insns. */
4971 static sbitmap pre_redundant_insns;
4973 /* Allocate vars used for PRE analysis. */
4975 static void
4976 alloc_pre_mem (int n_blocks, int n_exprs)
4978 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
4979 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
4980 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
4982 pre_optimal = NULL;
4983 pre_redundant = NULL;
4984 pre_insert_map = NULL;
4985 pre_delete_map = NULL;
4986 ae_in = NULL;
4987 ae_out = NULL;
4988 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
4990 /* pre_insert and pre_delete are allocated later. */
4993 /* Free vars used for PRE analysis. */
4995 static void
4996 free_pre_mem (void)
4998 sbitmap_vector_free (transp);
4999 sbitmap_vector_free (comp);
5001 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
5003 if (pre_optimal)
5004 sbitmap_vector_free (pre_optimal);
5005 if (pre_redundant)
5006 sbitmap_vector_free (pre_redundant);
5007 if (pre_insert_map)
5008 sbitmap_vector_free (pre_insert_map);
5009 if (pre_delete_map)
5010 sbitmap_vector_free (pre_delete_map);
5011 if (ae_in)
5012 sbitmap_vector_free (ae_in);
5013 if (ae_out)
5014 sbitmap_vector_free (ae_out);
5016 transp = comp = NULL;
5017 pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
5018 ae_in = ae_out = NULL;
5021 /* Top level routine to do the dataflow analysis needed by PRE. */
5023 static void
5024 compute_pre_data (void)
5026 sbitmap trapping_expr;
5027 basic_block bb;
5028 unsigned int ui;
5030 compute_local_properties (transp, comp, antloc, &expr_hash_table);
5031 sbitmap_vector_zero (ae_kill, last_basic_block);
5033 /* Collect expressions which might trap. */
5034 trapping_expr = sbitmap_alloc (expr_hash_table.n_elems);
5035 sbitmap_zero (trapping_expr);
5036 for (ui = 0; ui < expr_hash_table.size; ui++)
5038 struct expr *e;
5039 for (e = expr_hash_table.table[ui]; e != NULL; e = e->next_same_hash)
5040 if (may_trap_p (e->expr))
5041 SET_BIT (trapping_expr, e->bitmap_index);
5044 /* Compute ae_kill for each basic block using:
5046 ~(TRANSP | COMP)
5048 This is significantly faster than compute_ae_kill. */
5050 FOR_EACH_BB (bb)
5052 edge e;
5054 /* If the current block is the destination of an abnormal edge, we
5055 kill all trapping expressions because we won't be able to properly
5056 place the instruction on the edge. So make them neither
5057 anticipatable nor transparent. This is fairly conservative. */
5058 for (e = bb->pred; e ; e = e->pred_next)
5059 if (e->flags & EDGE_ABNORMAL)
5061 sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr);
5062 sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr);
5063 break;
5066 sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]);
5067 sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]);
5070 edge_list = pre_edge_lcm (gcse_file, expr_hash_table.n_elems, transp, comp, antloc,
5071 ae_kill, &pre_insert_map, &pre_delete_map);
5072 sbitmap_vector_free (antloc);
5073 antloc = NULL;
5074 sbitmap_vector_free (ae_kill);
5075 ae_kill = NULL;
5076 sbitmap_free (trapping_expr);
5079 /* PRE utilities */
5081 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
5082 block BB.
5084 VISITED is a pointer to a working buffer for tracking which BB's have
5085 been visited. It is NULL for the top-level call.
5087 We treat reaching expressions that go through blocks containing the same
5088 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
5089 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
5090 2 as not reaching. The intent is to improve the probability of finding
5091 only one reaching expression and to reduce register lifetimes by picking
5092 the closest such expression. */
5094 static int
5095 pre_expr_reaches_here_p_work (basic_block occr_bb, struct expr *expr, basic_block bb, char *visited)
5097 edge pred;
5099 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
5101 basic_block pred_bb = pred->src;
5103 if (pred->src == ENTRY_BLOCK_PTR
5104 /* Has predecessor has already been visited? */
5105 || visited[pred_bb->index])
5106 ;/* Nothing to do. */
5108 /* Does this predecessor generate this expression? */
5109 else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
5111 /* Is this the occurrence we're looking for?
5112 Note that there's only one generating occurrence per block
5113 so we just need to check the block number. */
5114 if (occr_bb == pred_bb)
5115 return 1;
5117 visited[pred_bb->index] = 1;
5119 /* Ignore this predecessor if it kills the expression. */
5120 else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
5121 visited[pred_bb->index] = 1;
5123 /* Neither gen nor kill. */
5124 else
5126 visited[pred_bb->index] = 1;
5127 if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
5128 return 1;
5132 /* All paths have been checked. */
5133 return 0;
5136 /* The wrapper for pre_expr_reaches_here_work that ensures that any
5137 memory allocated for that function is returned. */
5139 static int
5140 pre_expr_reaches_here_p (basic_block occr_bb, struct expr *expr, basic_block bb)
5142 int rval;
5143 char *visited = xcalloc (last_basic_block, 1);
5145 rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited);
5147 free (visited);
5148 return rval;
5152 /* Given an expr, generate RTL which we can insert at the end of a BB,
5153 or on an edge. Set the block number of any insns generated to
5154 the value of BB. */
5156 static rtx
5157 process_insert_insn (struct expr *expr)
5159 rtx reg = expr->reaching_reg;
5160 rtx exp = copy_rtx (expr->expr);
5161 rtx pat;
5163 start_sequence ();
5165 /* If the expression is something that's an operand, like a constant,
5166 just copy it to a register. */
5167 if (general_operand (exp, GET_MODE (reg)))
5168 emit_move_insn (reg, exp);
5170 /* Otherwise, make a new insn to compute this expression and make sure the
5171 insn will be recognized (this also adds any needed CLOBBERs). Copy the
5172 expression to make sure we don't have any sharing issues. */
5173 else if (insn_invalid_p (emit_insn (gen_rtx_SET (VOIDmode, reg, exp))))
5174 abort ();
5176 pat = get_insns ();
5177 end_sequence ();
5179 return pat;
5182 /* Add EXPR to the end of basic block BB.
5184 This is used by both the PRE and code hoisting.
5186 For PRE, we want to verify that the expr is either transparent
5187 or locally anticipatable in the target block. This check makes
5188 no sense for code hoisting. */
5190 static void
5191 insert_insn_end_bb (struct expr *expr, basic_block bb, int pre)
5193 rtx insn = bb->end;
5194 rtx new_insn;
5195 rtx reg = expr->reaching_reg;
5196 int regno = REGNO (reg);
5197 rtx pat, pat_end;
5199 pat = process_insert_insn (expr);
5200 if (pat == NULL_RTX || ! INSN_P (pat))
5201 abort ();
5203 pat_end = pat;
5204 while (NEXT_INSN (pat_end) != NULL_RTX)
5205 pat_end = NEXT_INSN (pat_end);
5207 /* If the last insn is a jump, insert EXPR in front [taking care to
5208 handle cc0, etc. properly]. Similarly we need to care trapping
5209 instructions in presence of non-call exceptions. */
5211 if (GET_CODE (insn) == JUMP_INSN
5212 || (GET_CODE (insn) == INSN
5213 && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL))))
5215 #ifdef HAVE_cc0
5216 rtx note;
5217 #endif
5218 /* It should always be the case that we can put these instructions
5219 anywhere in the basic block with performing PRE optimizations.
5220 Check this. */
5221 if (GET_CODE (insn) == INSN && pre
5222 && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
5223 && !TEST_BIT (transp[bb->index], expr->bitmap_index))
5224 abort ();
5226 /* If this is a jump table, then we can't insert stuff here. Since
5227 we know the previous real insn must be the tablejump, we insert
5228 the new instruction just before the tablejump. */
5229 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
5230 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
5231 insn = prev_real_insn (insn);
5233 #ifdef HAVE_cc0
5234 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
5235 if cc0 isn't set. */
5236 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
5237 if (note)
5238 insn = XEXP (note, 0);
5239 else
5241 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
5242 if (maybe_cc0_setter
5243 && INSN_P (maybe_cc0_setter)
5244 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
5245 insn = maybe_cc0_setter;
5247 #endif
5248 /* FIXME: What if something in cc0/jump uses value set in new insn? */
5249 new_insn = emit_insn_before (pat, insn);
5252 /* Likewise if the last insn is a call, as will happen in the presence
5253 of exception handling. */
5254 else if (GET_CODE (insn) == CALL_INSN
5255 && (bb->succ->succ_next || (bb->succ->flags & EDGE_ABNORMAL)))
5257 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
5258 we search backward and place the instructions before the first
5259 parameter is loaded. Do this for everyone for consistency and a
5260 presumption that we'll get better code elsewhere as well.
5262 It should always be the case that we can put these instructions
5263 anywhere in the basic block with performing PRE optimizations.
5264 Check this. */
5266 if (pre
5267 && !TEST_BIT (antloc[bb->index], expr->bitmap_index)
5268 && !TEST_BIT (transp[bb->index], expr->bitmap_index))
5269 abort ();
5271 /* Since different machines initialize their parameter registers
5272 in different orders, assume nothing. Collect the set of all
5273 parameter registers. */
5274 insn = find_first_parameter_load (insn, bb->head);
5276 /* If we found all the parameter loads, then we want to insert
5277 before the first parameter load.
5279 If we did not find all the parameter loads, then we might have
5280 stopped on the head of the block, which could be a CODE_LABEL.
5281 If we inserted before the CODE_LABEL, then we would be putting
5282 the insn in the wrong basic block. In that case, put the insn
5283 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
5284 while (GET_CODE (insn) == CODE_LABEL
5285 || NOTE_INSN_BASIC_BLOCK_P (insn))
5286 insn = NEXT_INSN (insn);
5288 new_insn = emit_insn_before (pat, insn);
5290 else
5291 new_insn = emit_insn_after (pat, insn);
5293 while (1)
5295 if (INSN_P (pat))
5297 add_label_notes (PATTERN (pat), new_insn);
5298 note_stores (PATTERN (pat), record_set_info, pat);
5300 if (pat == pat_end)
5301 break;
5302 pat = NEXT_INSN (pat);
5305 gcse_create_count++;
5307 if (gcse_file)
5309 fprintf (gcse_file, "PRE/HOIST: end of bb %d, insn %d, ",
5310 bb->index, INSN_UID (new_insn));
5311 fprintf (gcse_file, "copying expression %d to reg %d\n",
5312 expr->bitmap_index, regno);
5316 /* Insert partially redundant expressions on edges in the CFG to make
5317 the expressions fully redundant. */
5319 static int
5320 pre_edge_insert (struct edge_list *edge_list, struct expr **index_map)
5322 int e, i, j, num_edges, set_size, did_insert = 0;
5323 sbitmap *inserted;
5325 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
5326 if it reaches any of the deleted expressions. */
5328 set_size = pre_insert_map[0]->size;
5329 num_edges = NUM_EDGES (edge_list);
5330 inserted = sbitmap_vector_alloc (num_edges, expr_hash_table.n_elems);
5331 sbitmap_vector_zero (inserted, num_edges);
5333 for (e = 0; e < num_edges; e++)
5335 int indx;
5336 basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
5338 for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
5340 SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
5342 for (j = indx; insert && j < (int) expr_hash_table.n_elems; j++, insert >>= 1)
5343 if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
5345 struct expr *expr = index_map[j];
5346 struct occr *occr;
5348 /* Now look at each deleted occurrence of this expression. */
5349 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5351 if (! occr->deleted_p)
5352 continue;
5354 /* Insert this expression on this edge if if it would
5355 reach the deleted occurrence in BB. */
5356 if (!TEST_BIT (inserted[e], j))
5358 rtx insn;
5359 edge eg = INDEX_EDGE (edge_list, e);
5361 /* We can't insert anything on an abnormal and
5362 critical edge, so we insert the insn at the end of
5363 the previous block. There are several alternatives
5364 detailed in Morgans book P277 (sec 10.5) for
5365 handling this situation. This one is easiest for
5366 now. */
5368 if ((eg->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
5369 insert_insn_end_bb (index_map[j], bb, 0);
5370 else
5372 insn = process_insert_insn (index_map[j]);
5373 insert_insn_on_edge (insn, eg);
5376 if (gcse_file)
5378 fprintf (gcse_file, "PRE/HOIST: edge (%d,%d), ",
5379 bb->index,
5380 INDEX_EDGE_SUCC_BB (edge_list, e)->index);
5381 fprintf (gcse_file, "copy expression %d\n",
5382 expr->bitmap_index);
5385 update_ld_motion_stores (expr);
5386 SET_BIT (inserted[e], j);
5387 did_insert = 1;
5388 gcse_create_count++;
5395 sbitmap_vector_free (inserted);
5396 return did_insert;
5399 /* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
5400 Given "old_reg <- expr" (INSN), instead of adding after it
5401 reaching_reg <- old_reg
5402 it's better to do the following:
5403 reaching_reg <- expr
5404 old_reg <- reaching_reg
5405 because this way copy propagation can discover additional PRE
5406 opportunities. But if this fails, we try the old way.
5407 When "expr" is a store, i.e.
5408 given "MEM <- old_reg", instead of adding after it
5409 reaching_reg <- old_reg
5410 it's better to add it before as follows:
5411 reaching_reg <- old_reg
5412 MEM <- reaching_reg. */
5414 static void
5415 pre_insert_copy_insn (struct expr *expr, rtx insn)
5417 rtx reg = expr->reaching_reg;
5418 int regno = REGNO (reg);
5419 int indx = expr->bitmap_index;
5420 rtx pat = PATTERN (insn);
5421 rtx set, new_insn;
5422 rtx old_reg;
5423 int i;
5425 /* This block matches the logic in hash_scan_insn. */
5426 if (GET_CODE (pat) == SET)
5427 set = pat;
5428 else if (GET_CODE (pat) == PARALLEL)
5430 /* Search through the parallel looking for the set whose
5431 source was the expression that we're interested in. */
5432 set = NULL_RTX;
5433 for (i = 0; i < XVECLEN (pat, 0); i++)
5435 rtx x = XVECEXP (pat, 0, i);
5436 if (GET_CODE (x) == SET
5437 && expr_equiv_p (SET_SRC (x), expr->expr))
5439 set = x;
5440 break;
5444 else
5445 abort ();
5447 if (GET_CODE (SET_DEST (set)) == REG)
5449 old_reg = SET_DEST (set);
5450 /* Check if we can modify the set destination in the original insn. */
5451 if (validate_change (insn, &SET_DEST (set), reg, 0))
5453 new_insn = gen_move_insn (old_reg, reg);
5454 new_insn = emit_insn_after (new_insn, insn);
5456 /* Keep register set table up to date. */
5457 replace_one_set (REGNO (old_reg), insn, new_insn);
5458 record_one_set (regno, insn);
5460 else
5462 new_insn = gen_move_insn (reg, old_reg);
5463 new_insn = emit_insn_after (new_insn, insn);
5465 /* Keep register set table up to date. */
5466 record_one_set (regno, new_insn);
5469 else /* This is possible only in case of a store to memory. */
5471 old_reg = SET_SRC (set);
5472 new_insn = gen_move_insn (reg, old_reg);
5474 /* Check if we can modify the set source in the original insn. */
5475 if (validate_change (insn, &SET_SRC (set), reg, 0))
5476 new_insn = emit_insn_before (new_insn, insn);
5477 else
5478 new_insn = emit_insn_after (new_insn, insn);
5480 /* Keep register set table up to date. */
5481 record_one_set (regno, new_insn);
5484 gcse_create_count++;
5486 if (gcse_file)
5487 fprintf (gcse_file,
5488 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
5489 BLOCK_NUM (insn), INSN_UID (new_insn), indx,
5490 INSN_UID (insn), regno);
5493 /* Copy available expressions that reach the redundant expression
5494 to `reaching_reg'. */
5496 static void
5497 pre_insert_copies (void)
5499 unsigned int i, added_copy;
5500 struct expr *expr;
5501 struct occr *occr;
5502 struct occr *avail;
5504 /* For each available expression in the table, copy the result to
5505 `reaching_reg' if the expression reaches a deleted one.
5507 ??? The current algorithm is rather brute force.
5508 Need to do some profiling. */
5510 for (i = 0; i < expr_hash_table.size; i++)
5511 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
5513 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
5514 we don't want to insert a copy here because the expression may not
5515 really be redundant. So only insert an insn if the expression was
5516 deleted. This test also avoids further processing if the
5517 expression wasn't deleted anywhere. */
5518 if (expr->reaching_reg == NULL)
5519 continue;
5521 /* Set when we add a copy for that expression. */
5522 added_copy = 0;
5524 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5526 if (! occr->deleted_p)
5527 continue;
5529 for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
5531 rtx insn = avail->insn;
5533 /* No need to handle this one if handled already. */
5534 if (avail->copied_p)
5535 continue;
5537 /* Don't handle this one if it's a redundant one. */
5538 if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
5539 continue;
5541 /* Or if the expression doesn't reach the deleted one. */
5542 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
5543 expr,
5544 BLOCK_FOR_INSN (occr->insn)))
5545 continue;
5547 added_copy = 1;
5549 /* Copy the result of avail to reaching_reg. */
5550 pre_insert_copy_insn (expr, insn);
5551 avail->copied_p = 1;
5555 if (added_copy)
5556 update_ld_motion_stores (expr);
5560 /* Emit move from SRC to DEST noting the equivalence with expression computed
5561 in INSN. */
5562 static rtx
5563 gcse_emit_move_after (rtx src, rtx dest, rtx insn)
5565 rtx new;
5566 rtx set = single_set (insn), set2;
5567 rtx note;
5568 rtx eqv;
5570 /* This should never fail since we're creating a reg->reg copy
5571 we've verified to be valid. */
5573 new = emit_insn_after (gen_move_insn (dest, src), insn);
5575 /* Note the equivalence for local CSE pass. */
5576 set2 = single_set (new);
5577 if (!set2 || !rtx_equal_p (SET_DEST (set2), dest))
5578 return new;
5579 if ((note = find_reg_equal_equiv_note (insn)))
5580 eqv = XEXP (note, 0);
5581 else
5582 eqv = SET_SRC (set);
5584 set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (eqv));
5586 return new;
5589 /* Delete redundant computations.
5590 Deletion is done by changing the insn to copy the `reaching_reg' of
5591 the expression into the result of the SET. It is left to later passes
5592 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
5594 Returns nonzero if a change is made. */
5596 static int
5597 pre_delete (void)
5599 unsigned int i;
5600 int changed;
5601 struct expr *expr;
5602 struct occr *occr;
5604 changed = 0;
5605 for (i = 0; i < expr_hash_table.size; i++)
5606 for (expr = expr_hash_table.table[i];
5607 expr != NULL;
5608 expr = expr->next_same_hash)
5610 int indx = expr->bitmap_index;
5612 /* We only need to search antic_occr since we require
5613 ANTLOC != 0. */
5615 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
5617 rtx insn = occr->insn;
5618 rtx set;
5619 basic_block bb = BLOCK_FOR_INSN (insn);
5621 /* We only delete insns that have a single_set. */
5622 if (TEST_BIT (pre_delete_map[bb->index], indx)
5623 && (set = single_set (insn)) != 0)
5625 /* Create a pseudo-reg to store the result of reaching
5626 expressions into. Get the mode for the new pseudo from
5627 the mode of the original destination pseudo. */
5628 if (expr->reaching_reg == NULL)
5629 expr->reaching_reg
5630 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
5632 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
5633 delete_insn (insn);
5634 occr->deleted_p = 1;
5635 SET_BIT (pre_redundant_insns, INSN_CUID (insn));
5636 changed = 1;
5637 gcse_subst_count++;
5639 if (gcse_file)
5641 fprintf (gcse_file,
5642 "PRE: redundant insn %d (expression %d) in ",
5643 INSN_UID (insn), indx);
5644 fprintf (gcse_file, "bb %d, reaching reg is %d\n",
5645 bb->index, REGNO (expr->reaching_reg));
5651 return changed;
5654 /* Perform GCSE optimizations using PRE.
5655 This is called by one_pre_gcse_pass after all the dataflow analysis
5656 has been done.
5658 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
5659 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
5660 Compiler Design and Implementation.
5662 ??? A new pseudo reg is created to hold the reaching expression. The nice
5663 thing about the classical approach is that it would try to use an existing
5664 reg. If the register can't be adequately optimized [i.e. we introduce
5665 reload problems], one could add a pass here to propagate the new register
5666 through the block.
5668 ??? We don't handle single sets in PARALLELs because we're [currently] not
5669 able to copy the rest of the parallel when we insert copies to create full
5670 redundancies from partial redundancies. However, there's no reason why we
5671 can't handle PARALLELs in the cases where there are no partial
5672 redundancies. */
5674 static int
5675 pre_gcse (void)
5677 unsigned int i;
5678 int did_insert, changed;
5679 struct expr **index_map;
5680 struct expr *expr;
5682 /* Compute a mapping from expression number (`bitmap_index') to
5683 hash table entry. */
5685 index_map = xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
5686 for (i = 0; i < expr_hash_table.size; i++)
5687 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
5688 index_map[expr->bitmap_index] = expr;
5690 /* Reset bitmap used to track which insns are redundant. */
5691 pre_redundant_insns = sbitmap_alloc (max_cuid);
5692 sbitmap_zero (pre_redundant_insns);
5694 /* Delete the redundant insns first so that
5695 - we know what register to use for the new insns and for the other
5696 ones with reaching expressions
5697 - we know which insns are redundant when we go to create copies */
5699 changed = pre_delete ();
5701 did_insert = pre_edge_insert (edge_list, index_map);
5703 /* In other places with reaching expressions, copy the expression to the
5704 specially allocated pseudo-reg that reaches the redundant expr. */
5705 pre_insert_copies ();
5706 if (did_insert)
5708 commit_edge_insertions ();
5709 changed = 1;
5712 free (index_map);
5713 sbitmap_free (pre_redundant_insns);
5714 return changed;
5717 /* Top level routine to perform one PRE GCSE pass.
5719 Return nonzero if a change was made. */
5721 static int
5722 one_pre_gcse_pass (int pass)
5724 int changed = 0;
5726 gcse_subst_count = 0;
5727 gcse_create_count = 0;
5729 alloc_hash_table (max_cuid, &expr_hash_table, 0);
5730 add_noreturn_fake_exit_edges ();
5731 if (flag_gcse_lm)
5732 compute_ld_motion_mems ();
5734 compute_hash_table (&expr_hash_table);
5735 trim_ld_motion_mems ();
5736 if (gcse_file)
5737 dump_hash_table (gcse_file, "Expression", &expr_hash_table);
5739 if (expr_hash_table.n_elems > 0)
5741 alloc_pre_mem (last_basic_block, expr_hash_table.n_elems);
5742 compute_pre_data ();
5743 changed |= pre_gcse ();
5744 free_edge_list (edge_list);
5745 free_pre_mem ();
5748 free_ldst_mems ();
5749 remove_fake_edges ();
5750 free_hash_table (&expr_hash_table);
5752 if (gcse_file)
5754 fprintf (gcse_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
5755 current_function_name, pass, bytes_used);
5756 fprintf (gcse_file, "%d substs, %d insns created\n",
5757 gcse_subst_count, gcse_create_count);
5760 return changed;
5763 /* If X contains any LABEL_REF's, add REG_LABEL notes for them to INSN.
5764 If notes are added to an insn which references a CODE_LABEL, the
5765 LABEL_NUSES count is incremented. We have to add REG_LABEL notes,
5766 because the following loop optimization pass requires them. */
5768 /* ??? This is very similar to the loop.c add_label_notes function. We
5769 could probably share code here. */
5771 /* ??? If there was a jump optimization pass after gcse and before loop,
5772 then we would not need to do this here, because jump would add the
5773 necessary REG_LABEL notes. */
5775 static void
5776 add_label_notes (rtx x, rtx insn)
5778 enum rtx_code code = GET_CODE (x);
5779 int i, j;
5780 const char *fmt;
5782 if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
5784 /* This code used to ignore labels that referred to dispatch tables to
5785 avoid flow generating (slightly) worse code.
5787 We no longer ignore such label references (see LABEL_REF handling in
5788 mark_jump_label for additional information). */
5790 REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, XEXP (x, 0),
5791 REG_NOTES (insn));
5792 if (LABEL_P (XEXP (x, 0)))
5793 LABEL_NUSES (XEXP (x, 0))++;
5794 return;
5797 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
5799 if (fmt[i] == 'e')
5800 add_label_notes (XEXP (x, i), insn);
5801 else if (fmt[i] == 'E')
5802 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5803 add_label_notes (XVECEXP (x, i, j), insn);
5807 /* Compute transparent outgoing information for each block.
5809 An expression is transparent to an edge unless it is killed by
5810 the edge itself. This can only happen with abnormal control flow,
5811 when the edge is traversed through a call. This happens with
5812 non-local labels and exceptions.
5814 This would not be necessary if we split the edge. While this is
5815 normally impossible for abnormal critical edges, with some effort
5816 it should be possible with exception handling, since we still have
5817 control over which handler should be invoked. But due to increased
5818 EH table sizes, this may not be worthwhile. */
5820 static void
5821 compute_transpout (void)
5823 basic_block bb;
5824 unsigned int i;
5825 struct expr *expr;
5827 sbitmap_vector_ones (transpout, last_basic_block);
5829 FOR_EACH_BB (bb)
5831 /* Note that flow inserted a nop a the end of basic blocks that
5832 end in call instructions for reasons other than abnormal
5833 control flow. */
5834 if (GET_CODE (bb->end) != CALL_INSN)
5835 continue;
5837 for (i = 0; i < expr_hash_table.size; i++)
5838 for (expr = expr_hash_table.table[i]; expr ; expr = expr->next_same_hash)
5839 if (GET_CODE (expr->expr) == MEM)
5841 if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
5842 && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
5843 continue;
5845 /* ??? Optimally, we would use interprocedural alias
5846 analysis to determine if this mem is actually killed
5847 by this call. */
5848 RESET_BIT (transpout[bb->index], expr->bitmap_index);
5853 /* Removal of useless null pointer checks */
5855 /* Called via note_stores. X is set by SETTER. If X is a register we must
5856 invalidate nonnull_local and set nonnull_killed. DATA is really a
5857 `null_pointer_info *'.
5859 We ignore hard registers. */
5861 static void
5862 invalidate_nonnull_info (rtx x, rtx setter ATTRIBUTE_UNUSED, void *data)
5864 unsigned int regno;
5865 struct null_pointer_info *npi = (struct null_pointer_info *) data;
5867 while (GET_CODE (x) == SUBREG)
5868 x = SUBREG_REG (x);
5870 /* Ignore anything that is not a register or is a hard register. */
5871 if (GET_CODE (x) != REG
5872 || REGNO (x) < npi->min_reg
5873 || REGNO (x) >= npi->max_reg)
5874 return;
5876 regno = REGNO (x) - npi->min_reg;
5878 RESET_BIT (npi->nonnull_local[npi->current_block->index], regno);
5879 SET_BIT (npi->nonnull_killed[npi->current_block->index], regno);
5882 /* Do null-pointer check elimination for the registers indicated in
5883 NPI. NONNULL_AVIN and NONNULL_AVOUT are pre-allocated sbitmaps;
5884 they are not our responsibility to free. */
5886 static int
5887 delete_null_pointer_checks_1 (unsigned int *block_reg, sbitmap *nonnull_avin,
5888 sbitmap *nonnull_avout,
5889 struct null_pointer_info *npi)
5891 basic_block bb, current_block;
5892 sbitmap *nonnull_local = npi->nonnull_local;
5893 sbitmap *nonnull_killed = npi->nonnull_killed;
5894 int something_changed = 0;
5896 /* Compute local properties, nonnull and killed. A register will have
5897 the nonnull property if at the end of the current block its value is
5898 known to be nonnull. The killed property indicates that somewhere in
5899 the block any information we had about the register is killed.
5901 Note that a register can have both properties in a single block. That
5902 indicates that it's killed, then later in the block a new value is
5903 computed. */
5904 sbitmap_vector_zero (nonnull_local, last_basic_block);
5905 sbitmap_vector_zero (nonnull_killed, last_basic_block);
5907 FOR_EACH_BB (current_block)
5909 rtx insn, stop_insn;
5911 /* Set the current block for invalidate_nonnull_info. */
5912 npi->current_block = current_block;
5914 /* Scan each insn in the basic block looking for memory references and
5915 register sets. */
5916 stop_insn = NEXT_INSN (current_block->end);
5917 for (insn = current_block->head;
5918 insn != stop_insn;
5919 insn = NEXT_INSN (insn))
5921 rtx set;
5922 rtx reg;
5924 /* Ignore anything that is not a normal insn. */
5925 if (! INSN_P (insn))
5926 continue;
5928 /* Basically ignore anything that is not a simple SET. We do have
5929 to make sure to invalidate nonnull_local and set nonnull_killed
5930 for such insns though. */
5931 set = single_set (insn);
5932 if (!set)
5934 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5935 continue;
5938 /* See if we've got a usable memory load. We handle it first
5939 in case it uses its address register as a dest (which kills
5940 the nonnull property). */
5941 if (GET_CODE (SET_SRC (set)) == MEM
5942 && GET_CODE ((reg = XEXP (SET_SRC (set), 0))) == REG
5943 && REGNO (reg) >= npi->min_reg
5944 && REGNO (reg) < npi->max_reg)
5945 SET_BIT (nonnull_local[current_block->index],
5946 REGNO (reg) - npi->min_reg);
5948 /* Now invalidate stuff clobbered by this insn. */
5949 note_stores (PATTERN (insn), invalidate_nonnull_info, npi);
5951 /* And handle stores, we do these last since any sets in INSN can
5952 not kill the nonnull property if it is derived from a MEM
5953 appearing in a SET_DEST. */
5954 if (GET_CODE (SET_DEST (set)) == MEM
5955 && GET_CODE ((reg = XEXP (SET_DEST (set), 0))) == REG
5956 && REGNO (reg) >= npi->min_reg
5957 && REGNO (reg) < npi->max_reg)
5958 SET_BIT (nonnull_local[current_block->index],
5959 REGNO (reg) - npi->min_reg);
5963 /* Now compute global properties based on the local properties. This
5964 is a classic global availability algorithm. */
5965 compute_available (nonnull_local, nonnull_killed,
5966 nonnull_avout, nonnull_avin);
5968 /* Now look at each bb and see if it ends with a compare of a value
5969 against zero. */
5970 FOR_EACH_BB (bb)
5972 rtx last_insn = bb->end;
5973 rtx condition, earliest;
5974 int compare_and_branch;
5976 /* Since MIN_REG is always at least FIRST_PSEUDO_REGISTER, and
5977 since BLOCK_REG[BB] is zero if this block did not end with a
5978 comparison against zero, this condition works. */
5979 if (block_reg[bb->index] < npi->min_reg
5980 || block_reg[bb->index] >= npi->max_reg)
5981 continue;
5983 /* LAST_INSN is a conditional jump. Get its condition. */
5984 condition = get_condition (last_insn, &earliest, false);
5986 /* If we can't determine the condition then skip. */
5987 if (! condition)
5988 continue;
5990 /* Is the register known to have a nonzero value? */
5991 if (!TEST_BIT (nonnull_avout[bb->index], block_reg[bb->index] - npi->min_reg))
5992 continue;
5994 /* Try to compute whether the compare/branch at the loop end is one or
5995 two instructions. */
5996 if (earliest == last_insn)
5997 compare_and_branch = 1;
5998 else if (earliest == prev_nonnote_insn (last_insn))
5999 compare_and_branch = 2;
6000 else
6001 continue;
6003 /* We know the register in this comparison is nonnull at exit from
6004 this block. We can optimize this comparison. */
6005 if (GET_CODE (condition) == NE)
6007 rtx new_jump;
6009 new_jump = emit_jump_insn_after (gen_jump (JUMP_LABEL (last_insn)),
6010 last_insn);
6011 JUMP_LABEL (new_jump) = JUMP_LABEL (last_insn);
6012 LABEL_NUSES (JUMP_LABEL (new_jump))++;
6013 emit_barrier_after (new_jump);
6016 something_changed = 1;
6017 delete_insn (last_insn);
6018 if (compare_and_branch == 2)
6019 delete_insn (earliest);
6020 purge_dead_edges (bb);
6022 /* Don't check this block again. (Note that BLOCK_END is
6023 invalid here; we deleted the last instruction in the
6024 block.) */
6025 block_reg[bb->index] = 0;
6028 return something_changed;
6031 /* Find EQ/NE comparisons against zero which can be (indirectly) evaluated
6032 at compile time.
6034 This is conceptually similar to global constant/copy propagation and
6035 classic global CSE (it even uses the same dataflow equations as cprop).
6037 If a register is used as memory address with the form (mem (reg)), then we
6038 know that REG can not be zero at that point in the program. Any instruction
6039 which sets REG "kills" this property.
6041 So, if every path leading to a conditional branch has an available memory
6042 reference of that form, then we know the register can not have the value
6043 zero at the conditional branch.
6045 So we merely need to compute the local properties and propagate that data
6046 around the cfg, then optimize where possible.
6048 We run this pass two times. Once before CSE, then again after CSE. This
6049 has proven to be the most profitable approach. It is rare for new
6050 optimization opportunities of this nature to appear after the first CSE
6051 pass.
6053 This could probably be integrated with global cprop with a little work. */
6056 delete_null_pointer_checks (rtx f ATTRIBUTE_UNUSED)
6058 sbitmap *nonnull_avin, *nonnull_avout;
6059 unsigned int *block_reg;
6060 basic_block bb;
6061 int reg;
6062 int regs_per_pass;
6063 int max_reg = max_reg_num ();
6064 struct null_pointer_info npi;
6065 int something_changed = 0;
6067 /* If we have only a single block, or it is too expensive, give up. */
6068 if (n_basic_blocks <= 1
6069 || is_too_expensive (_ ("NULL pointer checks disabled")))
6070 return 0;
6072 /* We need four bitmaps, each with a bit for each register in each
6073 basic block. */
6074 regs_per_pass = get_bitmap_width (4, last_basic_block, max_reg);
6076 /* Allocate bitmaps to hold local and global properties. */
6077 npi.nonnull_local = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
6078 npi.nonnull_killed = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
6079 nonnull_avin = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
6080 nonnull_avout = sbitmap_vector_alloc (last_basic_block, regs_per_pass);
6082 /* Go through the basic blocks, seeing whether or not each block
6083 ends with a conditional branch whose condition is a comparison
6084 against zero. Record the register compared in BLOCK_REG. */
6085 block_reg = xcalloc (last_basic_block, sizeof (int));
6086 FOR_EACH_BB (bb)
6088 rtx last_insn = bb->end;
6089 rtx condition, earliest, reg;
6091 /* We only want conditional branches. */
6092 if (GET_CODE (last_insn) != JUMP_INSN
6093 || !any_condjump_p (last_insn)
6094 || !onlyjump_p (last_insn))
6095 continue;
6097 /* LAST_INSN is a conditional jump. Get its condition. */
6098 condition = get_condition (last_insn, &earliest, false);
6100 /* If we were unable to get the condition, or it is not an equality
6101 comparison against zero then there's nothing we can do. */
6102 if (!condition
6103 || (GET_CODE (condition) != NE && GET_CODE (condition) != EQ)
6104 || GET_CODE (XEXP (condition, 1)) != CONST_INT
6105 || (XEXP (condition, 1)
6106 != CONST0_RTX (GET_MODE (XEXP (condition, 0)))))
6107 continue;
6109 /* We must be checking a register against zero. */
6110 reg = XEXP (condition, 0);
6111 if (GET_CODE (reg) != REG)
6112 continue;
6114 block_reg[bb->index] = REGNO (reg);
6117 /* Go through the algorithm for each block of registers. */
6118 for (reg = FIRST_PSEUDO_REGISTER; reg < max_reg; reg += regs_per_pass)
6120 npi.min_reg = reg;
6121 npi.max_reg = MIN (reg + regs_per_pass, max_reg);
6122 something_changed |= delete_null_pointer_checks_1 (block_reg,
6123 nonnull_avin,
6124 nonnull_avout,
6125 &npi);
6128 /* Free the table of registers compared at the end of every block. */
6129 free (block_reg);
6131 /* Free bitmaps. */
6132 sbitmap_vector_free (npi.nonnull_local);
6133 sbitmap_vector_free (npi.nonnull_killed);
6134 sbitmap_vector_free (nonnull_avin);
6135 sbitmap_vector_free (nonnull_avout);
6137 return something_changed;
6140 /* Code Hoisting variables and subroutines. */
6142 /* Very busy expressions. */
6143 static sbitmap *hoist_vbein;
6144 static sbitmap *hoist_vbeout;
6146 /* Hoistable expressions. */
6147 static sbitmap *hoist_exprs;
6149 /* Dominator bitmaps. */
6150 dominance_info dominators;
6152 /* ??? We could compute post dominators and run this algorithm in
6153 reverse to perform tail merging, doing so would probably be
6154 more effective than the tail merging code in jump.c.
6156 It's unclear if tail merging could be run in parallel with
6157 code hoisting. It would be nice. */
6159 /* Allocate vars used for code hoisting analysis. */
6161 static void
6162 alloc_code_hoist_mem (int n_blocks, int n_exprs)
6164 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
6165 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
6166 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
6168 hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
6169 hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
6170 hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
6171 transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
6174 /* Free vars used for code hoisting analysis. */
6176 static void
6177 free_code_hoist_mem (void)
6179 sbitmap_vector_free (antloc);
6180 sbitmap_vector_free (transp);
6181 sbitmap_vector_free (comp);
6183 sbitmap_vector_free (hoist_vbein);
6184 sbitmap_vector_free (hoist_vbeout);
6185 sbitmap_vector_free (hoist_exprs);
6186 sbitmap_vector_free (transpout);
6188 free_dominance_info (dominators);
6191 /* Compute the very busy expressions at entry/exit from each block.
6193 An expression is very busy if all paths from a given point
6194 compute the expression. */
6196 static void
6197 compute_code_hoist_vbeinout (void)
6199 int changed, passes;
6200 basic_block bb;
6202 sbitmap_vector_zero (hoist_vbeout, last_basic_block);
6203 sbitmap_vector_zero (hoist_vbein, last_basic_block);
6205 passes = 0;
6206 changed = 1;
6208 while (changed)
6210 changed = 0;
6212 /* We scan the blocks in the reverse order to speed up
6213 the convergence. */
6214 FOR_EACH_BB_REVERSE (bb)
6216 changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index], antloc[bb->index],
6217 hoist_vbeout[bb->index], transp[bb->index]);
6218 if (bb->next_bb != EXIT_BLOCK_PTR)
6219 sbitmap_intersection_of_succs (hoist_vbeout[bb->index], hoist_vbein, bb->index);
6222 passes++;
6225 if (gcse_file)
6226 fprintf (gcse_file, "hoisting vbeinout computation: %d passes\n", passes);
6229 /* Top level routine to do the dataflow analysis needed by code hoisting. */
6231 static void
6232 compute_code_hoist_data (void)
6234 compute_local_properties (transp, comp, antloc, &expr_hash_table);
6235 compute_transpout ();
6236 compute_code_hoist_vbeinout ();
6237 dominators = calculate_dominance_info (CDI_DOMINATORS);
6238 if (gcse_file)
6239 fprintf (gcse_file, "\n");
6242 /* Determine if the expression identified by EXPR_INDEX would
6243 reach BB unimpared if it was placed at the end of EXPR_BB.
6245 It's unclear exactly what Muchnick meant by "unimpared". It seems
6246 to me that the expression must either be computed or transparent in
6247 *every* block in the path(s) from EXPR_BB to BB. Any other definition
6248 would allow the expression to be hoisted out of loops, even if
6249 the expression wasn't a loop invariant.
6251 Contrast this to reachability for PRE where an expression is
6252 considered reachable if *any* path reaches instead of *all*
6253 paths. */
6255 static int
6256 hoist_expr_reaches_here_p (basic_block expr_bb, int expr_index, basic_block bb, char *visited)
6258 edge pred;
6259 int visited_allocated_locally = 0;
6262 if (visited == NULL)
6264 visited_allocated_locally = 1;
6265 visited = xcalloc (last_basic_block, 1);
6268 for (pred = bb->pred; pred != NULL; pred = pred->pred_next)
6270 basic_block pred_bb = pred->src;
6272 if (pred->src == ENTRY_BLOCK_PTR)
6273 break;
6274 else if (pred_bb == expr_bb)
6275 continue;
6276 else if (visited[pred_bb->index])
6277 continue;
6279 /* Does this predecessor generate this expression? */
6280 else if (TEST_BIT (comp[pred_bb->index], expr_index))
6281 break;
6282 else if (! TEST_BIT (transp[pred_bb->index], expr_index))
6283 break;
6285 /* Not killed. */
6286 else
6288 visited[pred_bb->index] = 1;
6289 if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
6290 pred_bb, visited))
6291 break;
6294 if (visited_allocated_locally)
6295 free (visited);
6297 return (pred == NULL);
6300 /* Actually perform code hoisting. */
6302 static void
6303 hoist_code (void)
6305 basic_block bb, dominated;
6306 basic_block *domby;
6307 unsigned int domby_len;
6308 unsigned int i,j;
6309 struct expr **index_map;
6310 struct expr *expr;
6312 sbitmap_vector_zero (hoist_exprs, last_basic_block);
6314 /* Compute a mapping from expression number (`bitmap_index') to
6315 hash table entry. */
6317 index_map = xcalloc (expr_hash_table.n_elems, sizeof (struct expr *));
6318 for (i = 0; i < expr_hash_table.size; i++)
6319 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
6320 index_map[expr->bitmap_index] = expr;
6322 /* Walk over each basic block looking for potentially hoistable
6323 expressions, nothing gets hoisted from the entry block. */
6324 FOR_EACH_BB (bb)
6326 int found = 0;
6327 int insn_inserted_p;
6329 domby_len = get_dominated_by (dominators, bb, &domby);
6330 /* Examine each expression that is very busy at the exit of this
6331 block. These are the potentially hoistable expressions. */
6332 for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++)
6334 int hoistable = 0;
6336 if (TEST_BIT (hoist_vbeout[bb->index], i)
6337 && TEST_BIT (transpout[bb->index], i))
6339 /* We've found a potentially hoistable expression, now
6340 we look at every block BB dominates to see if it
6341 computes the expression. */
6342 for (j = 0; j < domby_len; j++)
6344 dominated = domby[j];
6345 /* Ignore self dominance. */
6346 if (bb == dominated)
6347 continue;
6348 /* We've found a dominated block, now see if it computes
6349 the busy expression and whether or not moving that
6350 expression to the "beginning" of that block is safe. */
6351 if (!TEST_BIT (antloc[dominated->index], i))
6352 continue;
6354 /* Note if the expression would reach the dominated block
6355 unimpared if it was placed at the end of BB.
6357 Keep track of how many times this expression is hoistable
6358 from a dominated block into BB. */
6359 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
6360 hoistable++;
6363 /* If we found more than one hoistable occurrence of this
6364 expression, then note it in the bitmap of expressions to
6365 hoist. It makes no sense to hoist things which are computed
6366 in only one BB, and doing so tends to pessimize register
6367 allocation. One could increase this value to try harder
6368 to avoid any possible code expansion due to register
6369 allocation issues; however experiments have shown that
6370 the vast majority of hoistable expressions are only movable
6371 from two successors, so raising this threshold is likely
6372 to nullify any benefit we get from code hoisting. */
6373 if (hoistable > 1)
6375 SET_BIT (hoist_exprs[bb->index], i);
6376 found = 1;
6380 /* If we found nothing to hoist, then quit now. */
6381 if (! found)
6383 free (domby);
6384 continue;
6387 /* Loop over all the hoistable expressions. */
6388 for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++)
6390 /* We want to insert the expression into BB only once, so
6391 note when we've inserted it. */
6392 insn_inserted_p = 0;
6394 /* These tests should be the same as the tests above. */
6395 if (TEST_BIT (hoist_vbeout[bb->index], i))
6397 /* We've found a potentially hoistable expression, now
6398 we look at every block BB dominates to see if it
6399 computes the expression. */
6400 for (j = 0; j < domby_len; j++)
6402 dominated = domby[j];
6403 /* Ignore self dominance. */
6404 if (bb == dominated)
6405 continue;
6407 /* We've found a dominated block, now see if it computes
6408 the busy expression and whether or not moving that
6409 expression to the "beginning" of that block is safe. */
6410 if (!TEST_BIT (antloc[dominated->index], i))
6411 continue;
6413 /* The expression is computed in the dominated block and
6414 it would be safe to compute it at the start of the
6415 dominated block. Now we have to determine if the
6416 expression would reach the dominated block if it was
6417 placed at the end of BB. */
6418 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
6420 struct expr *expr = index_map[i];
6421 struct occr *occr = expr->antic_occr;
6422 rtx insn;
6423 rtx set;
6425 /* Find the right occurrence of this expression. */
6426 while (BLOCK_FOR_INSN (occr->insn) != dominated && occr)
6427 occr = occr->next;
6429 /* Should never happen. */
6430 if (!occr)
6431 abort ();
6433 insn = occr->insn;
6435 set = single_set (insn);
6436 if (! set)
6437 abort ();
6439 /* Create a pseudo-reg to store the result of reaching
6440 expressions into. Get the mode for the new pseudo
6441 from the mode of the original destination pseudo. */
6442 if (expr->reaching_reg == NULL)
6443 expr->reaching_reg
6444 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
6446 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
6447 delete_insn (insn);
6448 occr->deleted_p = 1;
6449 if (!insn_inserted_p)
6451 insert_insn_end_bb (index_map[i], bb, 0);
6452 insn_inserted_p = 1;
6458 free (domby);
6461 free (index_map);
6464 /* Top level routine to perform one code hoisting (aka unification) pass
6466 Return nonzero if a change was made. */
6468 static int
6469 one_code_hoisting_pass (void)
6471 int changed = 0;
6473 alloc_hash_table (max_cuid, &expr_hash_table, 0);
6474 compute_hash_table (&expr_hash_table);
6475 if (gcse_file)
6476 dump_hash_table (gcse_file, "Code Hosting Expressions", &expr_hash_table);
6478 if (expr_hash_table.n_elems > 0)
6480 alloc_code_hoist_mem (last_basic_block, expr_hash_table.n_elems);
6481 compute_code_hoist_data ();
6482 hoist_code ();
6483 free_code_hoist_mem ();
6486 free_hash_table (&expr_hash_table);
6488 return changed;
6491 /* Here we provide the things required to do store motion towards
6492 the exit. In order for this to be effective, gcse also needed to
6493 be taught how to move a load when it is kill only by a store to itself.
6495 int i;
6496 float a[10];
6498 void foo(float scale)
6500 for (i=0; i<10; i++)
6501 a[i] *= scale;
6504 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
6505 the load out since its live around the loop, and stored at the bottom
6506 of the loop.
6508 The 'Load Motion' referred to and implemented in this file is
6509 an enhancement to gcse which when using edge based lcm, recognizes
6510 this situation and allows gcse to move the load out of the loop.
6512 Once gcse has hoisted the load, store motion can then push this
6513 load towards the exit, and we end up with no loads or stores of 'i'
6514 in the loop. */
6516 /* This will search the ldst list for a matching expression. If it
6517 doesn't find one, we create one and initialize it. */
6519 static struct ls_expr *
6520 ldst_entry (rtx x)
6522 struct ls_expr * ptr;
6524 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
6525 if (expr_equiv_p (ptr->pattern, x))
6526 break;
6528 if (!ptr)
6530 ptr = xmalloc (sizeof (struct ls_expr));
6532 ptr->next = pre_ldst_mems;
6533 ptr->expr = NULL;
6534 ptr->pattern = x;
6535 ptr->pattern_regs = NULL_RTX;
6536 ptr->loads = NULL_RTX;
6537 ptr->stores = NULL_RTX;
6538 ptr->reaching_reg = NULL_RTX;
6539 ptr->invalid = 0;
6540 ptr->index = 0;
6541 ptr->hash_index = 0;
6542 pre_ldst_mems = ptr;
6545 return ptr;
6548 /* Free up an individual ldst entry. */
6550 static void
6551 free_ldst_entry (struct ls_expr * ptr)
6553 free_INSN_LIST_list (& ptr->loads);
6554 free_INSN_LIST_list (& ptr->stores);
6556 free (ptr);
6559 /* Free up all memory associated with the ldst list. */
6561 static void
6562 free_ldst_mems (void)
6564 while (pre_ldst_mems)
6566 struct ls_expr * tmp = pre_ldst_mems;
6568 pre_ldst_mems = pre_ldst_mems->next;
6570 free_ldst_entry (tmp);
6573 pre_ldst_mems = NULL;
6576 /* Dump debugging info about the ldst list. */
6578 static void
6579 print_ldst_list (FILE * file)
6581 struct ls_expr * ptr;
6583 fprintf (file, "LDST list: \n");
6585 for (ptr = first_ls_expr(); ptr != NULL; ptr = next_ls_expr (ptr))
6587 fprintf (file, " Pattern (%3d): ", ptr->index);
6589 print_rtl (file, ptr->pattern);
6591 fprintf (file, "\n Loads : ");
6593 if (ptr->loads)
6594 print_rtl (file, ptr->loads);
6595 else
6596 fprintf (file, "(nil)");
6598 fprintf (file, "\n Stores : ");
6600 if (ptr->stores)
6601 print_rtl (file, ptr->stores);
6602 else
6603 fprintf (file, "(nil)");
6605 fprintf (file, "\n\n");
6608 fprintf (file, "\n");
6611 /* Returns 1 if X is in the list of ldst only expressions. */
6613 static struct ls_expr *
6614 find_rtx_in_ldst (rtx x)
6616 struct ls_expr * ptr;
6618 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6619 if (expr_equiv_p (ptr->pattern, x) && ! ptr->invalid)
6620 return ptr;
6622 return NULL;
6625 /* Assign each element of the list of mems a monotonically increasing value. */
6627 static int
6628 enumerate_ldsts (void)
6630 struct ls_expr * ptr;
6631 int n = 0;
6633 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
6634 ptr->index = n++;
6636 return n;
6639 /* Return first item in the list. */
6641 static inline struct ls_expr *
6642 first_ls_expr (void)
6644 return pre_ldst_mems;
6647 /* Return the next item in the list after the specified one. */
6649 static inline struct ls_expr *
6650 next_ls_expr (struct ls_expr * ptr)
6652 return ptr->next;
6655 /* Load Motion for loads which only kill themselves. */
6657 /* Return true if x is a simple MEM operation, with no registers or
6658 side effects. These are the types of loads we consider for the
6659 ld_motion list, otherwise we let the usual aliasing take care of it. */
6661 static int
6662 simple_mem (rtx x)
6664 if (GET_CODE (x) != MEM)
6665 return 0;
6667 if (MEM_VOLATILE_P (x))
6668 return 0;
6670 if (GET_MODE (x) == BLKmode)
6671 return 0;
6673 /* If we are handling exceptions, we must be careful with memory references
6674 that may trap. If we are not, the behavior is undefined, so we may just
6675 continue. */
6676 if (flag_non_call_exceptions && may_trap_p (x))
6677 return 0;
6679 if (side_effects_p (x))
6680 return 0;
6682 /* Do not consider function arguments passed on stack. */
6683 if (reg_mentioned_p (stack_pointer_rtx, x))
6684 return 0;
6686 if (flag_float_store && FLOAT_MODE_P (GET_MODE (x)))
6687 return 0;
6689 return 1;
6692 /* Make sure there isn't a buried reference in this pattern anywhere.
6693 If there is, invalidate the entry for it since we're not capable
6694 of fixing it up just yet.. We have to be sure we know about ALL
6695 loads since the aliasing code will allow all entries in the
6696 ld_motion list to not-alias itself. If we miss a load, we will get
6697 the wrong value since gcse might common it and we won't know to
6698 fix it up. */
6700 static void
6701 invalidate_any_buried_refs (rtx x)
6703 const char * fmt;
6704 int i, j;
6705 struct ls_expr * ptr;
6707 /* Invalidate it in the list. */
6708 if (GET_CODE (x) == MEM && simple_mem (x))
6710 ptr = ldst_entry (x);
6711 ptr->invalid = 1;
6714 /* Recursively process the insn. */
6715 fmt = GET_RTX_FORMAT (GET_CODE (x));
6717 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
6719 if (fmt[i] == 'e')
6720 invalidate_any_buried_refs (XEXP (x, i));
6721 else if (fmt[i] == 'E')
6722 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
6723 invalidate_any_buried_refs (XVECEXP (x, i, j));
6727 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
6728 being defined as MEM loads and stores to symbols, with no side effects
6729 and no registers in the expression. For a MEM destination, we also
6730 check that the insn is still valid if we replace the destination with a
6731 REG, as is done in update_ld_motion_stores. If there are any uses/defs
6732 which don't match this criteria, they are invalidated and trimmed out
6733 later. */
6735 static void
6736 compute_ld_motion_mems (void)
6738 struct ls_expr * ptr;
6739 basic_block bb;
6740 rtx insn;
6742 pre_ldst_mems = NULL;
6744 FOR_EACH_BB (bb)
6746 for (insn = bb->head;
6747 insn && insn != NEXT_INSN (bb->end);
6748 insn = NEXT_INSN (insn))
6750 if (INSN_P (insn))
6752 if (GET_CODE (PATTERN (insn)) == SET)
6754 rtx src = SET_SRC (PATTERN (insn));
6755 rtx dest = SET_DEST (PATTERN (insn));
6757 /* Check for a simple LOAD... */
6758 if (GET_CODE (src) == MEM && simple_mem (src))
6760 ptr = ldst_entry (src);
6761 if (GET_CODE (dest) == REG)
6762 ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
6763 else
6764 ptr->invalid = 1;
6766 else
6768 /* Make sure there isn't a buried load somewhere. */
6769 invalidate_any_buried_refs (src);
6772 /* Check for stores. Don't worry about aliased ones, they
6773 will block any movement we might do later. We only care
6774 about this exact pattern since those are the only
6775 circumstance that we will ignore the aliasing info. */
6776 if (GET_CODE (dest) == MEM && simple_mem (dest))
6778 ptr = ldst_entry (dest);
6780 if (GET_CODE (src) != MEM
6781 && GET_CODE (src) != ASM_OPERANDS
6782 /* Check for REG manually since want_to_gcse_p
6783 returns 0 for all REGs. */
6784 && (REG_P (src) || want_to_gcse_p (src)))
6785 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
6786 else
6787 ptr->invalid = 1;
6790 else
6791 invalidate_any_buried_refs (PATTERN (insn));
6797 /* Remove any references that have been either invalidated or are not in the
6798 expression list for pre gcse. */
6800 static void
6801 trim_ld_motion_mems (void)
6803 struct ls_expr * last = NULL;
6804 struct ls_expr * ptr = first_ls_expr ();
6806 while (ptr != NULL)
6808 int del = ptr->invalid;
6809 struct expr * expr = NULL;
6811 /* Delete if entry has been made invalid. */
6812 if (!del)
6814 unsigned int i;
6816 del = 1;
6817 /* Delete if we cannot find this mem in the expression list. */
6818 for (i = 0; i < expr_hash_table.size && del; i++)
6820 for (expr = expr_hash_table.table[i];
6821 expr != NULL;
6822 expr = expr->next_same_hash)
6823 if (expr_equiv_p (expr->expr, ptr->pattern))
6825 del = 0;
6826 break;
6831 if (del)
6833 if (last != NULL)
6835 last->next = ptr->next;
6836 free_ldst_entry (ptr);
6837 ptr = last->next;
6839 else
6841 pre_ldst_mems = pre_ldst_mems->next;
6842 free_ldst_entry (ptr);
6843 ptr = pre_ldst_mems;
6846 else
6848 /* Set the expression field if we are keeping it. */
6849 last = ptr;
6850 ptr->expr = expr;
6851 ptr = ptr->next;
6855 /* Show the world what we've found. */
6856 if (gcse_file && pre_ldst_mems != NULL)
6857 print_ldst_list (gcse_file);
6860 /* This routine will take an expression which we are replacing with
6861 a reaching register, and update any stores that are needed if
6862 that expression is in the ld_motion list. Stores are updated by
6863 copying their SRC to the reaching register, and then storing
6864 the reaching register into the store location. These keeps the
6865 correct value in the reaching register for the loads. */
6867 static void
6868 update_ld_motion_stores (struct expr * expr)
6870 struct ls_expr * mem_ptr;
6872 if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
6874 /* We can try to find just the REACHED stores, but is shouldn't
6875 matter to set the reaching reg everywhere... some might be
6876 dead and should be eliminated later. */
6878 /* We replace (set mem expr) with (set reg expr) (set mem reg)
6879 where reg is the reaching reg used in the load. We checked in
6880 compute_ld_motion_mems that we can replace (set mem expr) with
6881 (set reg expr) in that insn. */
6882 rtx list = mem_ptr->stores;
6884 for ( ; list != NULL_RTX; list = XEXP (list, 1))
6886 rtx insn = XEXP (list, 0);
6887 rtx pat = PATTERN (insn);
6888 rtx src = SET_SRC (pat);
6889 rtx reg = expr->reaching_reg;
6890 rtx copy, new;
6892 /* If we've already copied it, continue. */
6893 if (expr->reaching_reg == src)
6894 continue;
6896 if (gcse_file)
6898 fprintf (gcse_file, "PRE: store updated with reaching reg ");
6899 print_rtl (gcse_file, expr->reaching_reg);
6900 fprintf (gcse_file, ":\n ");
6901 print_inline_rtx (gcse_file, insn, 8);
6902 fprintf (gcse_file, "\n");
6905 copy = gen_move_insn ( reg, copy_rtx (SET_SRC (pat)));
6906 new = emit_insn_before (copy, insn);
6907 record_one_set (REGNO (reg), new);
6908 SET_SRC (pat) = reg;
6910 /* un-recognize this pattern since it's probably different now. */
6911 INSN_CODE (insn) = -1;
6912 gcse_create_count++;
6917 /* Store motion code. */
6919 #define ANTIC_STORE_LIST(x) ((x)->loads)
6920 #define AVAIL_STORE_LIST(x) ((x)->stores)
6921 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
6923 /* This is used to communicate the target bitvector we want to use in the
6924 reg_set_info routine when called via the note_stores mechanism. */
6925 static int * regvec;
6927 /* And current insn, for the same routine. */
6928 static rtx compute_store_table_current_insn;
6930 /* Used in computing the reverse edge graph bit vectors. */
6931 static sbitmap * st_antloc;
6933 /* Global holding the number of store expressions we are dealing with. */
6934 static int num_stores;
6936 /* Checks to set if we need to mark a register set. Called from note_stores. */
6938 static void
6939 reg_set_info (rtx dest, rtx setter ATTRIBUTE_UNUSED,
6940 void *data ATTRIBUTE_UNUSED)
6942 if (GET_CODE (dest) == SUBREG)
6943 dest = SUBREG_REG (dest);
6945 if (GET_CODE (dest) == REG)
6946 regvec[REGNO (dest)] = INSN_UID (compute_store_table_current_insn);
6949 /* Return zero if some of the registers in list X are killed
6950 due to set of registers in bitmap REGS_SET. */
6952 static bool
6953 store_ops_ok (rtx x, int *regs_set)
6955 rtx reg;
6957 for (; x; x = XEXP (x, 1))
6959 reg = XEXP (x, 0);
6960 if (regs_set[REGNO(reg)])
6961 return false;
6964 return true;
6967 /* Returns a list of registers mentioned in X. */
6968 static rtx
6969 extract_mentioned_regs (rtx x)
6971 return extract_mentioned_regs_helper (x, NULL_RTX);
6974 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
6975 registers. */
6976 static rtx
6977 extract_mentioned_regs_helper (rtx x, rtx accum)
6979 int i;
6980 enum rtx_code code;
6981 const char * fmt;
6983 /* Repeat is used to turn tail-recursion into iteration. */
6984 repeat:
6986 if (x == 0)
6987 return accum;
6989 code = GET_CODE (x);
6990 switch (code)
6992 case REG:
6993 return alloc_EXPR_LIST (0, x, accum);
6995 case MEM:
6996 x = XEXP (x, 0);
6997 goto repeat;
6999 case PRE_DEC:
7000 case PRE_INC:
7001 case POST_DEC:
7002 case POST_INC:
7003 /* We do not run this function with arguments having side effects. */
7004 abort ();
7006 case PC:
7007 case CC0: /*FIXME*/
7008 case CONST:
7009 case CONST_INT:
7010 case CONST_DOUBLE:
7011 case CONST_VECTOR:
7012 case SYMBOL_REF:
7013 case LABEL_REF:
7014 case ADDR_VEC:
7015 case ADDR_DIFF_VEC:
7016 return accum;
7018 default:
7019 break;
7022 i = GET_RTX_LENGTH (code) - 1;
7023 fmt = GET_RTX_FORMAT (code);
7025 for (; i >= 0; i--)
7027 if (fmt[i] == 'e')
7029 rtx tem = XEXP (x, i);
7031 /* If we are about to do the last recursive call
7032 needed at this level, change it into iteration. */
7033 if (i == 0)
7035 x = tem;
7036 goto repeat;
7039 accum = extract_mentioned_regs_helper (tem, accum);
7041 else if (fmt[i] == 'E')
7043 int j;
7045 for (j = 0; j < XVECLEN (x, i); j++)
7046 accum = extract_mentioned_regs_helper (XVECEXP (x, i, j), accum);
7050 return accum;
7053 /* Determine whether INSN is MEM store pattern that we will consider moving.
7054 REGS_SET_BEFORE is bitmap of registers set before (and including) the
7055 current insn, REGS_SET_AFTER is bitmap of registers set after (and
7056 including) the insn in this basic block. We must be passing through BB from
7057 head to end, as we are using this fact to speed things up.
7059 The results are stored this way:
7061 -- the first anticipatable expression is added into ANTIC_STORE_LIST
7062 -- if the processed expression is not anticipatable, NULL_RTX is added
7063 there instead, so that we can use it as indicator that no further
7064 expression of this type may be anticipatable
7065 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
7066 consequently, all of them but this head are dead and may be deleted.
7067 -- if the expression is not available, the insn due to that it fails to be
7068 available is stored in reaching_reg.
7070 The things are complicated a bit by fact that there already may be stores
7071 to the same MEM from other blocks; also caller must take care of the
7072 necessary cleanup of the temporary markers after end of the basic block.
7075 static void
7076 find_moveable_store (rtx insn, int *regs_set_before, int *regs_set_after)
7078 struct ls_expr * ptr;
7079 rtx dest, set, tmp;
7080 int check_anticipatable, check_available;
7081 basic_block bb = BLOCK_FOR_INSN (insn);
7083 set = single_set (insn);
7084 if (!set)
7085 return;
7087 dest = SET_DEST (set);
7089 if (GET_CODE (dest) != MEM || MEM_VOLATILE_P (dest)
7090 || GET_MODE (dest) == BLKmode)
7091 return;
7093 if (side_effects_p (dest))
7094 return;
7096 /* If we are handling exceptions, we must be careful with memory references
7097 that may trap. If we are not, the behavior is undefined, so we may just
7098 continue. */
7099 if (flag_non_call_exceptions && may_trap_p (dest))
7100 return;
7102 ptr = ldst_entry (dest);
7103 if (!ptr->pattern_regs)
7104 ptr->pattern_regs = extract_mentioned_regs (dest);
7106 /* Do not check for anticipatability if we either found one anticipatable
7107 store already, or tested for one and found out that it was killed. */
7108 check_anticipatable = 0;
7109 if (!ANTIC_STORE_LIST (ptr))
7110 check_anticipatable = 1;
7111 else
7113 tmp = XEXP (ANTIC_STORE_LIST (ptr), 0);
7114 if (tmp != NULL_RTX
7115 && BLOCK_FOR_INSN (tmp) != bb)
7116 check_anticipatable = 1;
7118 if (check_anticipatable)
7120 if (store_killed_before (dest, ptr->pattern_regs, insn, bb, regs_set_before))
7121 tmp = NULL_RTX;
7122 else
7123 tmp = insn;
7124 ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (tmp,
7125 ANTIC_STORE_LIST (ptr));
7128 /* It is not necessary to check whether store is available if we did
7129 it successfully before; if we failed before, do not bother to check
7130 until we reach the insn that caused us to fail. */
7131 check_available = 0;
7132 if (!AVAIL_STORE_LIST (ptr))
7133 check_available = 1;
7134 else
7136 tmp = XEXP (AVAIL_STORE_LIST (ptr), 0);
7137 if (BLOCK_FOR_INSN (tmp) != bb)
7138 check_available = 1;
7140 if (check_available)
7142 /* Check that we have already reached the insn at that the check
7143 failed last time. */
7144 if (LAST_AVAIL_CHECK_FAILURE (ptr))
7146 for (tmp = bb->end;
7147 tmp != insn && tmp != LAST_AVAIL_CHECK_FAILURE (ptr);
7148 tmp = PREV_INSN (tmp))
7149 continue;
7150 if (tmp == insn)
7151 check_available = 0;
7153 else
7154 check_available = store_killed_after (dest, ptr->pattern_regs, insn,
7155 bb, regs_set_after,
7156 &LAST_AVAIL_CHECK_FAILURE (ptr));
7158 if (!check_available)
7159 AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn, AVAIL_STORE_LIST (ptr));
7162 /* Find available and anticipatable stores. */
7164 static int
7165 compute_store_table (void)
7167 int ret;
7168 basic_block bb;
7169 unsigned regno;
7170 rtx insn, pat, tmp;
7171 int *last_set_in, *already_set;
7172 struct ls_expr * ptr, **prev_next_ptr_ptr;
7174 max_gcse_regno = max_reg_num ();
7176 reg_set_in_block = sbitmap_vector_alloc (last_basic_block,
7177 max_gcse_regno);
7178 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
7179 pre_ldst_mems = 0;
7180 last_set_in = xmalloc (sizeof (int) * max_gcse_regno);
7181 already_set = xmalloc (sizeof (int) * max_gcse_regno);
7183 /* Find all the stores we care about. */
7184 FOR_EACH_BB (bb)
7186 /* First compute the registers set in this block. */
7187 memset (last_set_in, 0, sizeof (int) * max_gcse_regno);
7188 regvec = last_set_in;
7190 for (insn = bb->head;
7191 insn != NEXT_INSN (bb->end);
7192 insn = NEXT_INSN (insn))
7194 if (! INSN_P (insn))
7195 continue;
7197 if (GET_CODE (insn) == CALL_INSN)
7199 bool clobbers_all = false;
7200 #ifdef NON_SAVING_SETJMP
7201 if (NON_SAVING_SETJMP
7202 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
7203 clobbers_all = true;
7204 #endif
7206 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
7207 if (clobbers_all
7208 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
7209 last_set_in[regno] = INSN_UID (insn);
7212 pat = PATTERN (insn);
7213 compute_store_table_current_insn = insn;
7214 note_stores (pat, reg_set_info, NULL);
7217 /* Record the set registers. */
7218 for (regno = 0; regno < max_gcse_regno; regno++)
7219 if (last_set_in[regno])
7220 SET_BIT (reg_set_in_block[bb->index], regno);
7222 /* Now find the stores. */
7223 memset (already_set, 0, sizeof (int) * max_gcse_regno);
7224 regvec = already_set;
7225 for (insn = bb->head;
7226 insn != NEXT_INSN (bb->end);
7227 insn = NEXT_INSN (insn))
7229 if (! INSN_P (insn))
7230 continue;
7232 if (GET_CODE (insn) == CALL_INSN)
7234 bool clobbers_all = false;
7235 #ifdef NON_SAVING_SETJMP
7236 if (NON_SAVING_SETJMP
7237 && find_reg_note (insn, REG_SETJMP, NULL_RTX))
7238 clobbers_all = true;
7239 #endif
7241 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
7242 if (clobbers_all
7243 || TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
7244 already_set[regno] = 1;
7247 pat = PATTERN (insn);
7248 note_stores (pat, reg_set_info, NULL);
7250 /* Now that we've marked regs, look for stores. */
7251 find_moveable_store (insn, already_set, last_set_in);
7253 /* Unmark regs that are no longer set. */
7254 for (regno = 0; regno < max_gcse_regno; regno++)
7255 if (last_set_in[regno] == INSN_UID (insn))
7256 last_set_in[regno] = 0;
7259 /* Clear temporary marks. */
7260 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7262 LAST_AVAIL_CHECK_FAILURE(ptr) = NULL_RTX;
7263 if (ANTIC_STORE_LIST (ptr)
7264 && (tmp = XEXP (ANTIC_STORE_LIST (ptr), 0)) == NULL_RTX)
7265 ANTIC_STORE_LIST (ptr) = XEXP (ANTIC_STORE_LIST (ptr), 1);
7269 /* Remove the stores that are not available anywhere, as there will
7270 be no opportunity to optimize them. */
7271 for (ptr = pre_ldst_mems, prev_next_ptr_ptr = &pre_ldst_mems;
7272 ptr != NULL;
7273 ptr = *prev_next_ptr_ptr)
7275 if (!AVAIL_STORE_LIST (ptr))
7277 *prev_next_ptr_ptr = ptr->next;
7278 free_ldst_entry (ptr);
7280 else
7281 prev_next_ptr_ptr = &ptr->next;
7284 ret = enumerate_ldsts ();
7286 if (gcse_file)
7288 fprintf (gcse_file, "ST_avail and ST_antic (shown under loads..)\n");
7289 print_ldst_list (gcse_file);
7292 free (last_set_in);
7293 free (already_set);
7294 return ret;
7297 /* Check to see if the load X is aliased with STORE_PATTERN.
7298 AFTER is true if we are checking the case when STORE_PATTERN occurs
7299 after the X. */
7301 static bool
7302 load_kills_store (rtx x, rtx store_pattern, int after)
7304 if (after)
7305 return anti_dependence (x, store_pattern);
7306 else
7307 return true_dependence (store_pattern, GET_MODE (store_pattern), x,
7308 rtx_addr_varies_p);
7311 /* Go through the entire insn X, looking for any loads which might alias
7312 STORE_PATTERN. Return true if found.
7313 AFTER is true if we are checking the case when STORE_PATTERN occurs
7314 after the insn X. */
7316 static bool
7317 find_loads (rtx x, rtx store_pattern, int after)
7319 const char * fmt;
7320 int i, j;
7321 int ret = false;
7323 if (!x)
7324 return false;
7326 if (GET_CODE (x) == SET)
7327 x = SET_SRC (x);
7329 if (GET_CODE (x) == MEM)
7331 if (load_kills_store (x, store_pattern, after))
7332 return true;
7335 /* Recursively process the insn. */
7336 fmt = GET_RTX_FORMAT (GET_CODE (x));
7338 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
7340 if (fmt[i] == 'e')
7341 ret |= find_loads (XEXP (x, i), store_pattern, after);
7342 else if (fmt[i] == 'E')
7343 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
7344 ret |= find_loads (XVECEXP (x, i, j), store_pattern, after);
7346 return ret;
7349 /* Check if INSN kills the store pattern X (is aliased with it).
7350 AFTER is true if we are checking the case when store X occurs
7351 after the insn. Return true if it it does. */
7353 static bool
7354 store_killed_in_insn (rtx x, rtx x_regs, rtx insn, int after)
7356 rtx reg, base, note;
7358 if (!INSN_P (insn))
7359 return false;
7361 if (GET_CODE (insn) == CALL_INSN)
7363 /* A normal or pure call might read from pattern,
7364 but a const call will not. */
7365 if (! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn))
7366 return true;
7368 /* But even a const call reads its parameters. Check whether the
7369 base of some of registers used in mem is stack pointer. */
7370 for (reg = x_regs; reg; reg = XEXP (reg, 1))
7372 base = find_base_term (XEXP (reg, 0));
7373 if (!base
7374 || (GET_CODE (base) == ADDRESS
7375 && GET_MODE (base) == Pmode
7376 && XEXP (base, 0) == stack_pointer_rtx))
7377 return true;
7380 return false;
7383 if (GET_CODE (PATTERN (insn)) == SET)
7385 rtx pat = PATTERN (insn);
7386 rtx dest = SET_DEST (pat);
7388 if (GET_CODE (dest) == SIGN_EXTRACT
7389 || GET_CODE (dest) == ZERO_EXTRACT)
7390 dest = XEXP (dest, 0);
7392 /* Check for memory stores to aliased objects. */
7393 if (GET_CODE (dest) == MEM
7394 && !expr_equiv_p (dest, x))
7396 if (after)
7398 if (output_dependence (dest, x))
7399 return true;
7401 else
7403 if (output_dependence (x, dest))
7404 return true;
7407 if (find_loads (SET_SRC (pat), x, after))
7408 return true;
7410 else if (find_loads (PATTERN (insn), x, after))
7411 return true;
7413 /* If this insn has a REG_EQUAL or REG_EQUIV note referencing a memory
7414 location aliased with X, then this insn kills X. */
7415 note = find_reg_equal_equiv_note (insn);
7416 if (! note)
7417 return false;
7418 note = XEXP (note, 0);
7420 /* However, if the note represents a must alias rather than a may
7421 alias relationship, then it does not kill X. */
7422 if (expr_equiv_p (note, x))
7423 return false;
7425 /* See if there are any aliased loads in the note. */
7426 return find_loads (note, x, after);
7429 /* Returns true if the expression X is loaded or clobbered on or after INSN
7430 within basic block BB. REGS_SET_AFTER is bitmap of registers set in
7431 or after the insn. X_REGS is list of registers mentioned in X. If the store
7432 is killed, return the last insn in that it occurs in FAIL_INSN. */
7434 static bool
7435 store_killed_after (rtx x, rtx x_regs, rtx insn, basic_block bb,
7436 int *regs_set_after, rtx *fail_insn)
7438 rtx last = bb->end, act;
7440 if (!store_ops_ok (x_regs, regs_set_after))
7442 /* We do not know where it will happen. */
7443 if (fail_insn)
7444 *fail_insn = NULL_RTX;
7445 return true;
7448 /* Scan from the end, so that fail_insn is determined correctly. */
7449 for (act = last; act != PREV_INSN (insn); act = PREV_INSN (act))
7450 if (store_killed_in_insn (x, x_regs, act, false))
7452 if (fail_insn)
7453 *fail_insn = act;
7454 return true;
7457 return false;
7460 /* Returns true if the expression X is loaded or clobbered on or before INSN
7461 within basic block BB. X_REGS is list of registers mentioned in X.
7462 REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
7463 static bool
7464 store_killed_before (rtx x, rtx x_regs, rtx insn, basic_block bb,
7465 int *regs_set_before)
7467 rtx first = bb->head;
7469 if (!store_ops_ok (x_regs, regs_set_before))
7470 return true;
7472 for ( ; insn != PREV_INSN (first); insn = PREV_INSN (insn))
7473 if (store_killed_in_insn (x, x_regs, insn, true))
7474 return true;
7476 return false;
7479 /* Fill in available, anticipatable, transparent and kill vectors in
7480 STORE_DATA, based on lists of available and anticipatable stores. */
7481 static void
7482 build_store_vectors (void)
7484 basic_block bb;
7485 int *regs_set_in_block;
7486 rtx insn, st;
7487 struct ls_expr * ptr;
7488 unsigned regno;
7490 /* Build the gen_vector. This is any store in the table which is not killed
7491 by aliasing later in its block. */
7492 ae_gen = sbitmap_vector_alloc (last_basic_block, num_stores);
7493 sbitmap_vector_zero (ae_gen, last_basic_block);
7495 st_antloc = sbitmap_vector_alloc (last_basic_block, num_stores);
7496 sbitmap_vector_zero (st_antloc, last_basic_block);
7498 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7500 for (st = AVAIL_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
7502 insn = XEXP (st, 0);
7503 bb = BLOCK_FOR_INSN (insn);
7505 /* If we've already seen an available expression in this block,
7506 we can delete this one (It occurs earlier in the block). We'll
7507 copy the SRC expression to an unused register in case there
7508 are any side effects. */
7509 if (TEST_BIT (ae_gen[bb->index], ptr->index))
7511 rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
7512 if (gcse_file)
7513 fprintf (gcse_file, "Removing redundant store:\n");
7514 replace_store_insn (r, XEXP (st, 0), bb, ptr);
7515 continue;
7517 SET_BIT (ae_gen[bb->index], ptr->index);
7520 for (st = ANTIC_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
7522 insn = XEXP (st, 0);
7523 bb = BLOCK_FOR_INSN (insn);
7524 SET_BIT (st_antloc[bb->index], ptr->index);
7528 ae_kill = sbitmap_vector_alloc (last_basic_block, num_stores);
7529 sbitmap_vector_zero (ae_kill, last_basic_block);
7531 transp = sbitmap_vector_alloc (last_basic_block, num_stores);
7532 sbitmap_vector_zero (transp, last_basic_block);
7533 regs_set_in_block = xmalloc (sizeof (int) * max_gcse_regno);
7535 FOR_EACH_BB (bb)
7537 for (regno = 0; regno < max_gcse_regno; regno++)
7538 regs_set_in_block[regno] = TEST_BIT (reg_set_in_block[bb->index], regno);
7540 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7542 if (store_killed_after (ptr->pattern, ptr->pattern_regs, bb->head,
7543 bb, regs_set_in_block, NULL))
7545 /* It should not be necessary to consider the expression
7546 killed if it is both anticipatable and available. */
7547 if (!TEST_BIT (st_antloc[bb->index], ptr->index)
7548 || !TEST_BIT (ae_gen[bb->index], ptr->index))
7549 SET_BIT (ae_kill[bb->index], ptr->index);
7551 else
7552 SET_BIT (transp[bb->index], ptr->index);
7556 free (regs_set_in_block);
7558 if (gcse_file)
7560 dump_sbitmap_vector (gcse_file, "st_antloc", "", st_antloc, last_basic_block);
7561 dump_sbitmap_vector (gcse_file, "st_kill", "", ae_kill, last_basic_block);
7562 dump_sbitmap_vector (gcse_file, "Transpt", "", transp, last_basic_block);
7563 dump_sbitmap_vector (gcse_file, "st_avloc", "", ae_gen, last_basic_block);
7567 /* Insert an instruction at the beginning of a basic block, and update
7568 the BLOCK_HEAD if needed. */
7570 static void
7571 insert_insn_start_bb (rtx insn, basic_block bb)
7573 /* Insert at start of successor block. */
7574 rtx prev = PREV_INSN (bb->head);
7575 rtx before = bb->head;
7576 while (before != 0)
7578 if (GET_CODE (before) != CODE_LABEL
7579 && (GET_CODE (before) != NOTE
7580 || NOTE_LINE_NUMBER (before) != NOTE_INSN_BASIC_BLOCK))
7581 break;
7582 prev = before;
7583 if (prev == bb->end)
7584 break;
7585 before = NEXT_INSN (before);
7588 insn = emit_insn_after (insn, prev);
7590 if (gcse_file)
7592 fprintf (gcse_file, "STORE_MOTION insert store at start of BB %d:\n",
7593 bb->index);
7594 print_inline_rtx (gcse_file, insn, 6);
7595 fprintf (gcse_file, "\n");
7599 /* This routine will insert a store on an edge. EXPR is the ldst entry for
7600 the memory reference, and E is the edge to insert it on. Returns nonzero
7601 if an edge insertion was performed. */
7603 static int
7604 insert_store (struct ls_expr * expr, edge e)
7606 rtx reg, insn;
7607 basic_block bb;
7608 edge tmp;
7610 /* We did all the deleted before this insert, so if we didn't delete a
7611 store, then we haven't set the reaching reg yet either. */
7612 if (expr->reaching_reg == NULL_RTX)
7613 return 0;
7615 if (e->flags & EDGE_FAKE)
7616 return 0;
7618 reg = expr->reaching_reg;
7619 insn = gen_move_insn (copy_rtx (expr->pattern), reg);
7621 /* If we are inserting this expression on ALL predecessor edges of a BB,
7622 insert it at the start of the BB, and reset the insert bits on the other
7623 edges so we don't try to insert it on the other edges. */
7624 bb = e->dest;
7625 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
7626 if (!(tmp->flags & EDGE_FAKE))
7628 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
7629 if (index == EDGE_INDEX_NO_EDGE)
7630 abort ();
7631 if (! TEST_BIT (pre_insert_map[index], expr->index))
7632 break;
7635 /* If tmp is NULL, we found an insertion on every edge, blank the
7636 insertion vector for these edges, and insert at the start of the BB. */
7637 if (!tmp && bb != EXIT_BLOCK_PTR)
7639 for (tmp = e->dest->pred; tmp ; tmp = tmp->pred_next)
7641 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
7642 RESET_BIT (pre_insert_map[index], expr->index);
7644 insert_insn_start_bb (insn, bb);
7645 return 0;
7648 /* We can't insert on this edge, so we'll insert at the head of the
7649 successors block. See Morgan, sec 10.5. */
7650 if ((e->flags & EDGE_ABNORMAL) == EDGE_ABNORMAL)
7652 insert_insn_start_bb (insn, bb);
7653 return 0;
7656 insert_insn_on_edge (insn, e);
7658 if (gcse_file)
7660 fprintf (gcse_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
7661 e->src->index, e->dest->index);
7662 print_inline_rtx (gcse_file, insn, 6);
7663 fprintf (gcse_file, "\n");
7666 return 1;
7669 /* Remove any REG_EQUAL or REG_EQUIV notes containing a reference to the
7670 memory location in SMEXPR set in basic block BB.
7672 This could be rather expensive. */
7674 static void
7675 remove_reachable_equiv_notes (basic_block bb, struct ls_expr *smexpr)
7677 edge *stack = xmalloc (sizeof (edge) * n_basic_blocks), act;
7678 sbitmap visited = sbitmap_alloc (last_basic_block);
7679 int stack_top = 0;
7680 rtx last, insn, note;
7681 rtx mem = smexpr->pattern;
7683 sbitmap_zero (visited);
7684 act = bb->succ;
7686 while (1)
7688 if (!act)
7690 if (!stack_top)
7692 free (stack);
7693 sbitmap_free (visited);
7694 return;
7696 act = stack[--stack_top];
7698 bb = act->dest;
7700 if (bb == EXIT_BLOCK_PTR
7701 || TEST_BIT (visited, bb->index)
7702 || TEST_BIT (ae_kill[bb->index], smexpr->index))
7704 act = act->succ_next;
7705 continue;
7707 SET_BIT (visited, bb->index);
7709 if (TEST_BIT (st_antloc[bb->index], smexpr->index))
7711 for (last = ANTIC_STORE_LIST (smexpr);
7712 BLOCK_FOR_INSN (XEXP (last, 0)) != bb;
7713 last = XEXP (last, 1))
7714 continue;
7715 last = XEXP (last, 0);
7717 else
7718 last = NEXT_INSN (bb->end);
7720 for (insn = bb->head; insn != last; insn = NEXT_INSN (insn))
7721 if (INSN_P (insn))
7723 note = find_reg_equal_equiv_note (insn);
7724 if (!note || !expr_equiv_p (XEXP (note, 0), mem))
7725 continue;
7727 if (gcse_file)
7728 fprintf (gcse_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
7729 INSN_UID (insn));
7730 remove_note (insn, note);
7732 act = act->succ_next;
7733 if (bb->succ)
7735 if (act)
7736 stack[stack_top++] = act;
7737 act = bb->succ;
7742 /* This routine will replace a store with a SET to a specified register. */
7744 static void
7745 replace_store_insn (rtx reg, rtx del, basic_block bb, struct ls_expr *smexpr)
7747 rtx insn, mem, note, set, ptr;
7749 mem = smexpr->pattern;
7750 insn = gen_move_insn (reg, SET_SRC (single_set (del)));
7751 insn = emit_insn_after (insn, del);
7753 if (gcse_file)
7755 fprintf (gcse_file,
7756 "STORE_MOTION delete insn in BB %d:\n ", bb->index);
7757 print_inline_rtx (gcse_file, del, 6);
7758 fprintf (gcse_file, "\nSTORE MOTION replaced with insn:\n ");
7759 print_inline_rtx (gcse_file, insn, 6);
7760 fprintf (gcse_file, "\n");
7763 for (ptr = ANTIC_STORE_LIST (smexpr); ptr; ptr = XEXP (ptr, 1))
7764 if (XEXP (ptr, 0) == del)
7766 XEXP (ptr, 0) = insn;
7767 break;
7769 delete_insn (del);
7771 /* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
7772 they are no longer accurate provided that they are reached by this
7773 definition, so drop them. */
7774 for (; insn != NEXT_INSN (bb->end); insn = NEXT_INSN (insn))
7775 if (INSN_P (insn))
7777 set = single_set (insn);
7778 if (!set)
7779 continue;
7780 if (expr_equiv_p (SET_DEST (set), mem))
7781 return;
7782 note = find_reg_equal_equiv_note (insn);
7783 if (!note || !expr_equiv_p (XEXP (note, 0), mem))
7784 continue;
7786 if (gcse_file)
7787 fprintf (gcse_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
7788 INSN_UID (insn));
7789 remove_note (insn, note);
7791 remove_reachable_equiv_notes (bb, smexpr);
7795 /* Delete a store, but copy the value that would have been stored into
7796 the reaching_reg for later storing. */
7798 static void
7799 delete_store (struct ls_expr * expr, basic_block bb)
7801 rtx reg, i, del;
7803 if (expr->reaching_reg == NULL_RTX)
7804 expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
7806 reg = expr->reaching_reg;
7808 for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
7810 del = XEXP (i, 0);
7811 if (BLOCK_FOR_INSN (del) == bb)
7813 /* We know there is only one since we deleted redundant
7814 ones during the available computation. */
7815 replace_store_insn (reg, del, bb, expr);
7816 break;
7821 /* Free memory used by store motion. */
7823 static void
7824 free_store_memory (void)
7826 free_ldst_mems ();
7828 if (ae_gen)
7829 sbitmap_vector_free (ae_gen);
7830 if (ae_kill)
7831 sbitmap_vector_free (ae_kill);
7832 if (transp)
7833 sbitmap_vector_free (transp);
7834 if (st_antloc)
7835 sbitmap_vector_free (st_antloc);
7836 if (pre_insert_map)
7837 sbitmap_vector_free (pre_insert_map);
7838 if (pre_delete_map)
7839 sbitmap_vector_free (pre_delete_map);
7840 if (reg_set_in_block)
7841 sbitmap_vector_free (reg_set_in_block);
7843 ae_gen = ae_kill = transp = st_antloc = NULL;
7844 pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
7847 /* Perform store motion. Much like gcse, except we move expressions the
7848 other way by looking at the flowgraph in reverse. */
7850 static void
7851 store_motion (void)
7853 basic_block bb;
7854 int x;
7855 struct ls_expr * ptr;
7856 int update_flow = 0;
7858 if (gcse_file)
7860 fprintf (gcse_file, "before store motion\n");
7861 print_rtl (gcse_file, get_insns ());
7864 init_alias_analysis ();
7866 /* Find all the available and anticipatable stores. */
7867 num_stores = compute_store_table ();
7868 if (num_stores == 0)
7870 sbitmap_vector_free (reg_set_in_block);
7871 end_alias_analysis ();
7872 return;
7875 /* Now compute kill & transp vectors. */
7876 build_store_vectors ();
7877 add_noreturn_fake_exit_edges ();
7878 connect_infinite_loops_to_exit ();
7880 edge_list = pre_edge_rev_lcm (gcse_file, num_stores, transp, ae_gen,
7881 st_antloc, ae_kill, &pre_insert_map,
7882 &pre_delete_map);
7884 /* Now we want to insert the new stores which are going to be needed. */
7885 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
7887 FOR_EACH_BB (bb)
7888 if (TEST_BIT (pre_delete_map[bb->index], ptr->index))
7889 delete_store (ptr, bb);
7891 for (x = 0; x < NUM_EDGES (edge_list); x++)
7892 if (TEST_BIT (pre_insert_map[x], ptr->index))
7893 update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
7896 if (update_flow)
7897 commit_edge_insertions ();
7899 free_store_memory ();
7900 free_edge_list (edge_list);
7901 remove_fake_edges ();
7902 end_alias_analysis ();
7906 /* Entry point for jump bypassing optimization pass. */
7909 bypass_jumps (FILE *file)
7911 int changed;
7913 /* We do not construct an accurate cfg in functions which call
7914 setjmp, so just punt to be safe. */
7915 if (current_function_calls_setjmp)
7916 return 0;
7918 /* For calling dump_foo fns from gdb. */
7919 debug_stderr = stderr;
7920 gcse_file = file;
7922 /* Identify the basic block information for this function, including
7923 successors and predecessors. */
7924 max_gcse_regno = max_reg_num ();
7926 if (file)
7927 dump_flow_info (file);
7929 /* Return if there's nothing to do, or it is too expensive */
7930 if (n_basic_blocks <= 1 || is_too_expensive (_ ("jump bypassing disabled")))
7931 return 0;
7933 gcc_obstack_init (&gcse_obstack);
7934 bytes_used = 0;
7936 /* We need alias. */
7937 init_alias_analysis ();
7939 /* Record where pseudo-registers are set. This data is kept accurate
7940 during each pass. ??? We could also record hard-reg information here
7941 [since it's unchanging], however it is currently done during hash table
7942 computation.
7944 It may be tempting to compute MEM set information here too, but MEM sets
7945 will be subject to code motion one day and thus we need to compute
7946 information about memory sets when we build the hash tables. */
7948 alloc_reg_set_mem (max_gcse_regno);
7949 compute_sets (get_insns ());
7951 max_gcse_regno = max_reg_num ();
7952 alloc_gcse_mem (get_insns ());
7953 changed = one_cprop_pass (1, 1, 1);
7954 free_gcse_mem ();
7956 if (file)
7958 fprintf (file, "BYPASS of %s: %d basic blocks, ",
7959 current_function_name, n_basic_blocks);
7960 fprintf (file, "%d bytes\n\n", bytes_used);
7963 obstack_free (&gcse_obstack, NULL);
7964 free_reg_set_mem ();
7966 /* We are finished with alias. */
7967 end_alias_analysis ();
7968 allocate_reg_info (max_reg_num (), FALSE, FALSE);
7970 return changed;
7973 /* Return true if the graph is too expensive to optimize. PASS is the
7974 optimization about to be performed. */
7976 static bool
7977 is_too_expensive (const char *pass)
7979 /* Trying to perform global optimizations on flow graphs which have
7980 a high connectivity will take a long time and is unlikely to be
7981 particularly useful.
7983 In normal circumstances a cfg should have about twice as many
7984 edges as blocks. But we do not want to punish small functions
7985 which have a couple switch statements. Rather than simply
7986 threshold the number of blocks, uses something with a more
7987 graceful degradation. */
7988 if (n_edges > 20000 + n_basic_blocks * 4)
7990 if (warn_disabled_optimization)
7991 warning ("%s: %d basic blocks and %d edges/basic block",
7992 pass, n_basic_blocks, n_edges / n_basic_blocks);
7994 return true;
7997 /* If allocating memory for the cprop bitmap would take up too much
7998 storage it's better just to disable the optimization. */
7999 if ((n_basic_blocks
8000 * SBITMAP_SET_SIZE (max_reg_num ())
8001 * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
8003 if (warn_disabled_optimization)
8004 warning ("%s: %d basic blocks and %d registers",
8005 pass, n_basic_blocks, max_reg_num ());
8007 return true;
8010 return false;
8013 #include "gt-gcse.h"