Daily bump.
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1 /* Global common subexpression elimination/Partial redundancy elimination
2 and global constant/copy propagation for GNU compiler.
3 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
4 2006, 2007 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
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 COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /* TODO
23 - reordering of memory allocation and freeing to be more space efficient
24 - do rough calc of how many regs are needed in each block, and a rough
25 calc of how many regs are available in each class and use that to
26 throttle back the code in cases where RTX_COST is minimal.
27 - a store to the same address as a load does not kill the load if the
28 source of the store is also the destination of the load. Handling this
29 allows more load motion, particularly out of loops.
30 - ability to realloc sbitmap vectors would allow one initial computation
31 of reg_set_in_block with only subsequent additions, rather than
32 recomputing it for each pass
36 /* References searched while implementing this.
38 Compilers Principles, Techniques and Tools
39 Aho, Sethi, Ullman
40 Addison-Wesley, 1988
42 Global Optimization by Suppression of Partial Redundancies
43 E. Morel, C. Renvoise
44 communications of the acm, Vol. 22, Num. 2, Feb. 1979
46 A Portable Machine-Independent Global Optimizer - Design and Measurements
47 Frederick Chow
48 Stanford Ph.D. thesis, Dec. 1983
50 A Fast Algorithm for Code Movement Optimization
51 D.M. Dhamdhere
52 SIGPLAN Notices, Vol. 23, Num. 10, Oct. 1988
54 A Solution to a Problem with Morel and Renvoise's
55 Global Optimization by Suppression of Partial Redundancies
56 K-H Drechsler, M.P. Stadel
57 ACM TOPLAS, Vol. 10, Num. 4, Oct. 1988
59 Practical Adaptation of the Global Optimization
60 Algorithm of Morel and Renvoise
61 D.M. Dhamdhere
62 ACM TOPLAS, Vol. 13, Num. 2. Apr. 1991
64 Efficiently Computing Static Single Assignment Form and the Control
65 Dependence Graph
66 R. Cytron, J. Ferrante, B.K. Rosen, M.N. Wegman, and F.K. Zadeck
67 ACM TOPLAS, Vol. 13, Num. 4, Oct. 1991
69 Lazy Code Motion
70 J. Knoop, O. Ruthing, B. Steffen
71 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
73 What's In a Region? Or Computing Control Dependence Regions in Near-Linear
74 Time for Reducible Flow Control
75 Thomas Ball
76 ACM Letters on Programming Languages and Systems,
77 Vol. 2, Num. 1-4, Mar-Dec 1993
79 An Efficient Representation for Sparse Sets
80 Preston Briggs, Linda Torczon
81 ACM Letters on Programming Languages and Systems,
82 Vol. 2, Num. 1-4, Mar-Dec 1993
84 A Variation of Knoop, Ruthing, and Steffen's Lazy Code Motion
85 K-H Drechsler, M.P. Stadel
86 ACM SIGPLAN Notices, Vol. 28, Num. 5, May 1993
88 Partial Dead Code Elimination
89 J. Knoop, O. Ruthing, B. Steffen
90 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
92 Effective Partial Redundancy Elimination
93 P. Briggs, K.D. Cooper
94 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
96 The Program Structure Tree: Computing Control Regions in Linear Time
97 R. Johnson, D. Pearson, K. Pingali
98 ACM SIGPLAN Notices, Vol. 29, Num. 6, Jun. 1994
100 Optimal Code Motion: Theory and Practice
101 J. Knoop, O. Ruthing, B. Steffen
102 ACM TOPLAS, Vol. 16, Num. 4, Jul. 1994
104 The power of assignment motion
105 J. Knoop, O. Ruthing, B. Steffen
106 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
108 Global code motion / global value numbering
109 C. Click
110 ACM SIGPLAN Notices Vol. 30, Num. 6, Jun. 1995, '95 Conference on PLDI
112 Value Driven Redundancy Elimination
113 L.T. Simpson
114 Rice University Ph.D. thesis, Apr. 1996
116 Value Numbering
117 L.T. Simpson
118 Massively Scalar Compiler Project, Rice University, Sep. 1996
120 High Performance Compilers for Parallel Computing
121 Michael Wolfe
122 Addison-Wesley, 1996
124 Advanced Compiler Design and Implementation
125 Steven Muchnick
126 Morgan Kaufmann, 1997
128 Building an Optimizing Compiler
129 Robert Morgan
130 Digital Press, 1998
132 People wishing to speed up the code here should read:
133 Elimination Algorithms for Data Flow Analysis
134 B.G. Ryder, M.C. Paull
135 ACM Computing Surveys, Vol. 18, Num. 3, Sep. 1986
137 How to Analyze Large Programs Efficiently and Informatively
138 D.M. Dhamdhere, B.K. Rosen, F.K. Zadeck
139 ACM SIGPLAN Notices Vol. 27, Num. 7, Jul. 1992, '92 Conference on PLDI
141 People wishing to do something different can find various possibilities
142 in the above papers and elsewhere.
145 #include "config.h"
146 #include "system.h"
147 #include "coretypes.h"
148 #include "tm.h"
149 #include "toplev.h"
151 #include "rtl.h"
152 #include "tree.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"
170 #include "timevar.h"
171 #include "tree-pass.h"
172 #include "hashtab.h"
173 #include "df.h"
174 #include "dbgcnt.h"
176 /* Propagate flow information through back edges and thus enable PRE's
177 moving loop invariant calculations out of loops.
179 Originally this tended to create worse overall code, but several
180 improvements during the development of PRE seem to have made following
181 back edges generally a win.
183 Note much of the loop invariant code motion done here would normally
184 be done by loop.c, which has more heuristics for when to move invariants
185 out of loops. At some point we might need to move some of those
186 heuristics into gcse.c. */
188 /* We support GCSE via Partial Redundancy Elimination. PRE optimizations
189 are a superset of those done by GCSE.
191 We perform the following steps:
193 1) Compute basic block information.
195 2) Compute table of places where registers are set.
197 3) Perform copy/constant propagation.
199 4) Perform global cse using lazy code motion if not optimizing
200 for size, or code hoisting if we are.
202 5) Perform another pass of copy/constant propagation.
204 Two passes of copy/constant propagation are done because the first one
205 enables more GCSE and the second one helps to clean up the copies that
206 GCSE creates. This is needed more for PRE than for Classic because Classic
207 GCSE will try to use an existing register containing the common
208 subexpression rather than create a new one. This is harder to do for PRE
209 because of the code motion (which Classic GCSE doesn't do).
211 Expressions we are interested in GCSE-ing are of the form
212 (set (pseudo-reg) (expression)).
213 Function want_to_gcse_p says what these are.
215 PRE handles moving invariant expressions out of loops (by treating them as
216 partially redundant).
218 Eventually it would be nice to replace cse.c/gcse.c with SSA (static single
219 assignment) based GVN (global value numbering). L. T. Simpson's paper
220 (Rice University) on value numbering is a useful reference for this.
222 **********************
224 We used to support multiple passes but there are diminishing returns in
225 doing so. The first pass usually makes 90% of the changes that are doable.
226 A second pass can make a few more changes made possible by the first pass.
227 Experiments show any further passes don't make enough changes to justify
228 the expense.
230 A study of spec92 using an unlimited number of passes:
231 [1 pass] = 1208 substitutions, [2] = 577, [3] = 202, [4] = 192, [5] = 83,
232 [6] = 34, [7] = 17, [8] = 9, [9] = 4, [10] = 4, [11] = 2,
233 [12] = 2, [13] = 1, [15] = 1, [16] = 2, [41] = 1
235 It was found doing copy propagation between each pass enables further
236 substitutions.
238 PRE is quite expensive in complicated functions because the DFA can take
239 a while to converge. Hence we only perform one pass. The parameter
240 max-gcse-passes can be modified if one wants to experiment.
242 **********************
244 The steps for PRE are:
246 1) Build the hash table of expressions we wish to GCSE (expr_hash_table).
248 2) Perform the data flow analysis for PRE.
250 3) Delete the redundant instructions
252 4) Insert the required copies [if any] that make the partially
253 redundant instructions fully redundant.
255 5) For other reaching expressions, insert an instruction to copy the value
256 to a newly created pseudo that will reach the redundant instruction.
258 The deletion is done first so that when we do insertions we
259 know which pseudo reg to use.
261 Various papers have argued that PRE DFA is expensive (O(n^2)) and others
262 argue it is not. The number of iterations for the algorithm to converge
263 is typically 2-4 so I don't view it as that expensive (relatively speaking).
265 PRE GCSE depends heavily on the second CSE pass to clean up the copies
266 we create. To make an expression reach the place where it's redundant,
267 the result of the expression is copied to a new register, and the redundant
268 expression is deleted by replacing it with this new register. Classic GCSE
269 doesn't have this problem as much as it computes the reaching defs of
270 each register in each block and thus can try to use an existing
271 register. */
273 /* GCSE global vars. */
275 /* Note whether or not we should run jump optimization after gcse. We
276 want to do this for two cases.
278 * If we changed any jumps via cprop.
280 * If we added any labels via edge splitting. */
281 static int run_jump_opt_after_gcse;
283 /* An obstack for our working variables. */
284 static struct obstack gcse_obstack;
286 struct reg_use {rtx reg_rtx; };
288 /* Hash table of expressions. */
290 struct expr
292 /* The expression (SET_SRC for expressions, PATTERN for assignments). */
293 rtx expr;
294 /* Index in the available expression bitmaps. */
295 int bitmap_index;
296 /* Next entry with the same hash. */
297 struct expr *next_same_hash;
298 /* List of anticipatable occurrences in basic blocks in the function.
299 An "anticipatable occurrence" is one that is the first occurrence in the
300 basic block, the operands are not modified in the basic block prior
301 to the occurrence and the output is not used between the start of
302 the block and the occurrence. */
303 struct occr *antic_occr;
304 /* List of available occurrence in basic blocks in the function.
305 An "available occurrence" is one that is the last occurrence in the
306 basic block and the operands are not modified by following statements in
307 the basic block [including this insn]. */
308 struct occr *avail_occr;
309 /* Non-null if the computation is PRE redundant.
310 The value is the newly created pseudo-reg to record a copy of the
311 expression in all the places that reach the redundant copy. */
312 rtx reaching_reg;
315 /* Occurrence of an expression.
316 There is one per basic block. If a pattern appears more than once the
317 last appearance is used [or first for anticipatable expressions]. */
319 struct occr
321 /* Next occurrence of this expression. */
322 struct occr *next;
323 /* The insn that computes the expression. */
324 rtx insn;
325 /* Nonzero if this [anticipatable] occurrence has been deleted. */
326 char deleted_p;
327 /* Nonzero if this [available] occurrence has been copied to
328 reaching_reg. */
329 /* ??? This is mutually exclusive with deleted_p, so they could share
330 the same byte. */
331 char copied_p;
334 /* Expression and copy propagation hash tables.
335 Each hash table is an array of buckets.
336 ??? It is known that if it were an array of entries, structure elements
337 `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is
338 not clear whether in the final analysis a sufficient amount of memory would
339 be saved as the size of the available expression bitmaps would be larger
340 [one could build a mapping table without holes afterwards though].
341 Someday I'll perform the computation and figure it out. */
343 struct hash_table
345 /* The table itself.
346 This is an array of `expr_hash_table_size' elements. */
347 struct expr **table;
349 /* Size of the hash table, in elements. */
350 unsigned int size;
352 /* Number of hash table elements. */
353 unsigned int n_elems;
355 /* Whether the table is expression of copy propagation one. */
356 int set_p;
359 /* Expression hash table. */
360 static struct hash_table expr_hash_table;
362 /* Copy propagation hash table. */
363 static struct hash_table set_hash_table;
365 /* Mapping of uids to cuids.
366 Only real insns get cuids. */
367 static int *uid_cuid;
369 /* Highest UID in UID_CUID. */
370 static int max_uid;
372 /* Get the cuid of an insn. */
373 #ifdef ENABLE_CHECKING
374 #define INSN_CUID(INSN) \
375 (gcc_assert (INSN_UID (INSN) <= max_uid), uid_cuid[INSN_UID (INSN)])
376 #else
377 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
378 #endif
380 /* Number of cuids. */
381 static int max_cuid;
383 /* Maximum register number in function prior to doing gcse + 1.
384 Registers created during this pass have regno >= max_gcse_regno.
385 This is named with "gcse" to not collide with global of same name. */
386 static unsigned int max_gcse_regno;
388 /* Table of registers that are modified.
390 For each register, each element is a list of places where the pseudo-reg
391 is set.
393 For simplicity, GCSE is done on sets of pseudo-regs only. PRE GCSE only
394 requires knowledge of which blocks kill which regs [and thus could use
395 a bitmap instead of the lists `reg_set_table' uses].
397 `reg_set_table' and could be turned into an array of bitmaps (num-bbs x
398 num-regs) [however perhaps it may be useful to keep the data as is]. One
399 advantage of recording things this way is that `reg_set_table' is fairly
400 sparse with respect to pseudo regs but for hard regs could be fairly dense
401 [relatively speaking]. And recording sets of pseudo-regs in lists speeds
402 up functions like compute_transp since in the case of pseudo-regs we only
403 need to iterate over the number of times a pseudo-reg is set, not over the
404 number of basic blocks [clearly there is a bit of a slow down in the cases
405 where a pseudo is set more than once in a block, however it is believed
406 that the net effect is to speed things up]. This isn't done for hard-regs
407 because recording call-clobbered hard-regs in `reg_set_table' at each
408 function call can consume a fair bit of memory, and iterating over
409 hard-regs stored this way in compute_transp will be more expensive. */
411 typedef struct reg_set
413 /* The next setting of this register. */
414 struct reg_set *next;
415 /* The index of the block where it was set. */
416 int bb_index;
417 } reg_set;
419 static reg_set **reg_set_table;
421 /* Size of `reg_set_table'.
422 The table starts out at max_gcse_regno + slop, and is enlarged as
423 necessary. */
424 static int reg_set_table_size;
426 /* Amount to grow `reg_set_table' by when it's full. */
427 #define REG_SET_TABLE_SLOP 100
429 /* This is a list of expressions which are MEMs and will be used by load
430 or store motion.
431 Load motion tracks MEMs which aren't killed by
432 anything except itself. (i.e., loads and stores to a single location).
433 We can then allow movement of these MEM refs with a little special
434 allowance. (all stores copy the same value to the reaching reg used
435 for the loads). This means all values used to store into memory must have
436 no side effects so we can re-issue the setter value.
437 Store Motion uses this structure as an expression table to track stores
438 which look interesting, and might be moveable towards the exit block. */
440 struct ls_expr
442 struct expr * expr; /* Gcse expression reference for LM. */
443 rtx pattern; /* Pattern of this mem. */
444 rtx pattern_regs; /* List of registers mentioned by the mem. */
445 rtx loads; /* INSN list of loads seen. */
446 rtx stores; /* INSN list of stores seen. */
447 struct ls_expr * next; /* Next in the list. */
448 int invalid; /* Invalid for some reason. */
449 int index; /* If it maps to a bitmap index. */
450 unsigned int hash_index; /* Index when in a hash table. */
451 rtx reaching_reg; /* Register to use when re-writing. */
454 /* Array of implicit set patterns indexed by basic block index. */
455 static rtx *implicit_sets;
457 /* Head of the list of load/store memory refs. */
458 static struct ls_expr * pre_ldst_mems = NULL;
460 /* Hashtable for the load/store memory refs. */
461 static htab_t pre_ldst_table = NULL;
463 /* Bitmap containing one bit for each register in the program.
464 Used when performing GCSE to track which registers have been set since
465 the start of the basic block. */
466 static regset reg_set_bitmap;
468 /* For each block, a bitmap of registers set in the block.
469 This is used by compute_transp.
470 It is computed during hash table computation and not by compute_sets
471 as it includes registers added since the last pass (or between cprop and
472 gcse) and it's currently not easy to realloc sbitmap vectors. */
473 static sbitmap *reg_set_in_block;
475 /* Array, indexed by basic block number for a list of insns which modify
476 memory within that block. */
477 static rtx * modify_mem_list;
478 static bitmap modify_mem_list_set;
480 /* This array parallels modify_mem_list, but is kept canonicalized. */
481 static rtx * canon_modify_mem_list;
483 /* Bitmap indexed by block numbers to record which blocks contain
484 function calls. */
485 static bitmap blocks_with_calls;
487 /* Various variables for statistics gathering. */
489 /* Memory used in a pass.
490 This isn't intended to be absolutely precise. Its intent is only
491 to keep an eye on memory usage. */
492 static int bytes_used;
494 /* GCSE substitutions made. */
495 static int gcse_subst_count;
496 /* Number of copy instructions created. */
497 static int gcse_create_count;
498 /* Number of local constants propagated. */
499 static int local_const_prop_count;
500 /* Number of local copies propagated. */
501 static int local_copy_prop_count;
502 /* Number of global constants propagated. */
503 static int global_const_prop_count;
504 /* Number of global copies propagated. */
505 static int global_copy_prop_count;
507 /* For available exprs */
508 static sbitmap *ae_kill, *ae_gen;
510 static void compute_can_copy (void);
511 static void *gmalloc (size_t) ATTRIBUTE_MALLOC;
512 static void *gcalloc (size_t, size_t) ATTRIBUTE_MALLOC;
513 static void *grealloc (void *, size_t);
514 static void *gcse_alloc (unsigned long);
515 static void alloc_gcse_mem (void);
516 static void free_gcse_mem (void);
517 static void alloc_reg_set_mem (int);
518 static void free_reg_set_mem (void);
519 static void record_one_set (int, rtx);
520 static void record_set_info (rtx, const_rtx, void *);
521 static void compute_sets (void);
522 static void hash_scan_insn (rtx, struct hash_table *, int);
523 static void hash_scan_set (rtx, rtx, struct hash_table *);
524 static void hash_scan_clobber (rtx, rtx, struct hash_table *);
525 static void hash_scan_call (rtx, rtx, struct hash_table *);
526 static int want_to_gcse_p (rtx);
527 static bool can_assign_to_reg_p (rtx);
528 static bool gcse_constant_p (const_rtx);
529 static int oprs_unchanged_p (const_rtx, const_rtx, int);
530 static int oprs_anticipatable_p (const_rtx, const_rtx);
531 static int oprs_available_p (const_rtx, const_rtx);
532 static void insert_expr_in_table (rtx, enum machine_mode, rtx, int, int,
533 struct hash_table *);
534 static void insert_set_in_table (rtx, rtx, struct hash_table *);
535 static unsigned int hash_expr (const_rtx, enum machine_mode, int *, int);
536 static unsigned int hash_set (int, int);
537 static int expr_equiv_p (const_rtx, const_rtx);
538 static void record_last_reg_set_info (rtx, int);
539 static void record_last_mem_set_info (rtx);
540 static void record_last_set_info (rtx, const_rtx, void *);
541 static void compute_hash_table (struct hash_table *);
542 static void alloc_hash_table (int, struct hash_table *, int);
543 static void free_hash_table (struct hash_table *);
544 static void compute_hash_table_work (struct hash_table *);
545 static void dump_hash_table (FILE *, const char *, struct hash_table *);
546 static struct expr *lookup_set (unsigned int, struct hash_table *);
547 static struct expr *next_set (unsigned int, struct expr *);
548 static void reset_opr_set_tables (void);
549 static int oprs_not_set_p (const_rtx, const_rtx);
550 static void mark_call (rtx);
551 static void mark_set (rtx, rtx);
552 static void mark_clobber (rtx, rtx);
553 static void mark_oprs_set (rtx);
554 static void alloc_cprop_mem (int, int);
555 static void free_cprop_mem (void);
556 static void compute_transp (const_rtx, int, sbitmap *, int);
557 static void compute_transpout (void);
558 static void compute_local_properties (sbitmap *, sbitmap *, sbitmap *,
559 struct hash_table *);
560 static void compute_cprop_data (void);
561 static void find_used_regs (rtx *, void *);
562 static int try_replace_reg (rtx, rtx, rtx);
563 static struct expr *find_avail_set (int, rtx);
564 static int cprop_jump (basic_block, rtx, rtx, rtx, rtx);
565 static void mems_conflict_for_gcse_p (rtx, const_rtx, void *);
566 static int load_killed_in_block_p (const_basic_block, int, const_rtx, int);
567 static void canon_list_insert (rtx, const_rtx, void *);
568 static int cprop_insn (rtx, int);
569 static int cprop (int);
570 static void find_implicit_sets (void);
571 static int one_cprop_pass (int, bool, bool);
572 static bool constprop_register (rtx, rtx, rtx, bool);
573 static struct expr *find_bypass_set (int, int);
574 static bool reg_killed_on_edge (const_rtx, const_edge);
575 static int bypass_block (basic_block, rtx, rtx);
576 static int bypass_conditional_jumps (void);
577 static void alloc_pre_mem (int, int);
578 static void free_pre_mem (void);
579 static void compute_pre_data (void);
580 static int pre_expr_reaches_here_p (basic_block, struct expr *,
581 basic_block);
582 static void insert_insn_end_basic_block (struct expr *, basic_block, int);
583 static void pre_insert_copy_insn (struct expr *, rtx);
584 static void pre_insert_copies (void);
585 static int pre_delete (void);
586 static int pre_gcse (void);
587 static int one_pre_gcse_pass (int);
588 static void add_label_notes (rtx, rtx);
589 static void alloc_code_hoist_mem (int, int);
590 static void free_code_hoist_mem (void);
591 static void compute_code_hoist_vbeinout (void);
592 static void compute_code_hoist_data (void);
593 static int hoist_expr_reaches_here_p (basic_block, int, basic_block, char *);
594 static void hoist_code (void);
595 static int one_code_hoisting_pass (void);
596 static rtx process_insert_insn (struct expr *);
597 static int pre_edge_insert (struct edge_list *, struct expr **);
598 static int pre_expr_reaches_here_p_work (basic_block, struct expr *,
599 basic_block, char *);
600 static struct ls_expr * ldst_entry (rtx);
601 static void free_ldst_entry (struct ls_expr *);
602 static void free_ldst_mems (void);
603 static void print_ldst_list (FILE *);
604 static struct ls_expr * find_rtx_in_ldst (rtx);
605 static int enumerate_ldsts (void);
606 static inline struct ls_expr * first_ls_expr (void);
607 static inline struct ls_expr * next_ls_expr (struct ls_expr *);
608 static int simple_mem (const_rtx);
609 static void invalidate_any_buried_refs (rtx);
610 static void compute_ld_motion_mems (void);
611 static void trim_ld_motion_mems (void);
612 static void update_ld_motion_stores (struct expr *);
613 static void reg_set_info (rtx, const_rtx, void *);
614 static void reg_clear_last_set (rtx, const_rtx, void *);
615 static bool store_ops_ok (const_rtx, int *);
616 static rtx extract_mentioned_regs (rtx);
617 static rtx extract_mentioned_regs_helper (rtx, rtx);
618 static void find_moveable_store (rtx, int *, int *);
619 static int compute_store_table (void);
620 static bool load_kills_store (const_rtx, const_rtx, int);
621 static bool find_loads (const_rtx, const_rtx, int);
622 static bool store_killed_in_insn (const_rtx, const_rtx, const_rtx, int);
623 static bool store_killed_after (const_rtx, const_rtx, const_rtx, const_basic_block, int *, rtx *);
624 static bool store_killed_before (const_rtx, const_rtx, const_rtx, const_basic_block, int *);
625 static void build_store_vectors (void);
626 static void insert_insn_start_basic_block (rtx, basic_block);
627 static int insert_store (struct ls_expr *, edge);
628 static void remove_reachable_equiv_notes (basic_block, struct ls_expr *);
629 static void replace_store_insn (rtx, rtx, basic_block, struct ls_expr *);
630 static void delete_store (struct ls_expr *, basic_block);
631 static void free_store_memory (void);
632 static void store_motion (void);
633 static void free_insn_expr_list_list (rtx *);
634 static void clear_modify_mem_tables (void);
635 static void free_modify_mem_tables (void);
636 static rtx gcse_emit_move_after (rtx, rtx, rtx);
637 static void local_cprop_find_used_regs (rtx *, void *);
638 static bool do_local_cprop (rtx, rtx, bool, rtx*);
639 static bool adjust_libcall_notes (rtx, rtx, rtx, rtx*);
640 static void local_cprop_pass (bool);
641 static bool is_too_expensive (const char *);
644 /* Entry point for global common subexpression elimination.
645 F is the first instruction in the function. Return nonzero if a
646 change is mode. */
648 static int
649 gcse_main (rtx f ATTRIBUTE_UNUSED)
651 int changed, pass;
652 /* Bytes used at start of pass. */
653 int initial_bytes_used;
654 /* Maximum number of bytes used by a pass. */
655 int max_pass_bytes;
656 /* Point to release obstack data from for each pass. */
657 char *gcse_obstack_bottom;
659 /* We do not construct an accurate cfg in functions which call
660 setjmp, so just punt to be safe. */
661 if (current_function_calls_setjmp)
662 return 0;
664 /* Assume that we do not need to run jump optimizations after gcse. */
665 run_jump_opt_after_gcse = 0;
667 /* Identify the basic block information for this function, including
668 successors and predecessors. */
669 max_gcse_regno = max_reg_num ();
671 df_note_add_problem ();
672 df_analyze ();
674 if (dump_file)
675 dump_flow_info (dump_file, dump_flags);
677 /* Return if there's nothing to do, or it is too expensive. */
678 if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1
679 || is_too_expensive (_("GCSE disabled")))
680 return 0;
682 gcc_obstack_init (&gcse_obstack);
683 bytes_used = 0;
685 /* We need alias. */
686 init_alias_analysis ();
687 /* Record where pseudo-registers are set. This data is kept accurate
688 during each pass. ??? We could also record hard-reg information here
689 [since it's unchanging], however it is currently done during hash table
690 computation.
692 It may be tempting to compute MEM set information here too, but MEM sets
693 will be subject to code motion one day and thus we need to compute
694 information about memory sets when we build the hash tables. */
696 alloc_reg_set_mem (max_gcse_regno);
697 compute_sets ();
699 pass = 0;
700 initial_bytes_used = bytes_used;
701 max_pass_bytes = 0;
702 gcse_obstack_bottom = gcse_alloc (1);
703 changed = 1;
704 while (changed && pass < MAX_GCSE_PASSES)
706 changed = 0;
707 if (dump_file)
708 fprintf (dump_file, "GCSE pass %d\n\n", pass + 1);
710 /* Initialize bytes_used to the space for the pred/succ lists,
711 and the reg_set_table data. */
712 bytes_used = initial_bytes_used;
714 /* Each pass may create new registers, so recalculate each time. */
715 max_gcse_regno = max_reg_num ();
717 alloc_gcse_mem ();
719 /* Don't allow constant propagation to modify jumps
720 during this pass. */
721 timevar_push (TV_CPROP1);
722 changed = one_cprop_pass (pass + 1, false, false);
723 timevar_pop (TV_CPROP1);
725 if (optimize_size)
726 /* Do nothing. */ ;
727 else
729 timevar_push (TV_PRE);
730 changed |= one_pre_gcse_pass (pass + 1);
731 /* We may have just created new basic blocks. Release and
732 recompute various things which are sized on the number of
733 basic blocks. */
734 if (changed)
736 free_modify_mem_tables ();
737 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
738 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
740 free_reg_set_mem ();
741 alloc_reg_set_mem (max_reg_num ());
742 compute_sets ();
743 run_jump_opt_after_gcse = 1;
744 timevar_pop (TV_PRE);
747 if (max_pass_bytes < bytes_used)
748 max_pass_bytes = bytes_used;
750 /* Free up memory, then reallocate for code hoisting. We can
751 not re-use the existing allocated memory because the tables
752 will not have info for the insns or registers created by
753 partial redundancy elimination. */
754 free_gcse_mem ();
756 /* It does not make sense to run code hoisting unless we are optimizing
757 for code size -- it rarely makes programs faster, and can make
758 them bigger if we did partial redundancy elimination (when optimizing
759 for space, we don't run the partial redundancy algorithms). */
760 if (optimize_size)
762 timevar_push (TV_HOIST);
763 max_gcse_regno = max_reg_num ();
764 alloc_gcse_mem ();
765 changed |= one_code_hoisting_pass ();
766 free_gcse_mem ();
768 if (max_pass_bytes < bytes_used)
769 max_pass_bytes = bytes_used;
770 timevar_pop (TV_HOIST);
773 if (dump_file)
775 fprintf (dump_file, "\n");
776 fflush (dump_file);
779 obstack_free (&gcse_obstack, gcse_obstack_bottom);
780 pass++;
783 /* Do one last pass of copy propagation, including cprop into
784 conditional jumps. */
786 max_gcse_regno = max_reg_num ();
787 alloc_gcse_mem ();
788 /* This time, go ahead and allow cprop to alter jumps. */
789 timevar_push (TV_CPROP2);
790 one_cprop_pass (pass + 1, true, true);
791 timevar_pop (TV_CPROP2);
792 free_gcse_mem ();
794 if (dump_file)
796 fprintf (dump_file, "GCSE of %s: %d basic blocks, ",
797 current_function_name (), n_basic_blocks);
798 fprintf (dump_file, "%d pass%s, %d bytes\n\n",
799 pass, pass > 1 ? "es" : "", max_pass_bytes);
802 obstack_free (&gcse_obstack, NULL);
803 free_reg_set_mem ();
805 /* We are finished with alias. */
806 end_alias_analysis ();
808 if (!optimize_size && flag_gcse_sm)
810 timevar_push (TV_LSM);
811 store_motion ();
812 timevar_pop (TV_LSM);
815 /* Record where pseudo-registers are set. */
816 return run_jump_opt_after_gcse;
819 /* Misc. utilities. */
821 /* Nonzero for each mode that supports (set (reg) (reg)).
822 This is trivially true for integer and floating point values.
823 It may or may not be true for condition codes. */
824 static char can_copy[(int) NUM_MACHINE_MODES];
826 /* Compute which modes support reg/reg copy operations. */
828 static void
829 compute_can_copy (void)
831 int i;
832 #ifndef AVOID_CCMODE_COPIES
833 rtx reg, insn;
834 #endif
835 memset (can_copy, 0, NUM_MACHINE_MODES);
837 start_sequence ();
838 for (i = 0; i < NUM_MACHINE_MODES; i++)
839 if (GET_MODE_CLASS (i) == MODE_CC)
841 #ifdef AVOID_CCMODE_COPIES
842 can_copy[i] = 0;
843 #else
844 reg = gen_rtx_REG ((enum machine_mode) i, LAST_VIRTUAL_REGISTER + 1);
845 insn = emit_insn (gen_rtx_SET (VOIDmode, reg, reg));
846 if (recog (PATTERN (insn), insn, NULL) >= 0)
847 can_copy[i] = 1;
848 #endif
850 else
851 can_copy[i] = 1;
853 end_sequence ();
856 /* Returns whether the mode supports reg/reg copy operations. */
858 bool
859 can_copy_p (enum machine_mode mode)
861 static bool can_copy_init_p = false;
863 if (! can_copy_init_p)
865 compute_can_copy ();
866 can_copy_init_p = true;
869 return can_copy[mode] != 0;
872 /* Cover function to xmalloc to record bytes allocated. */
874 static void *
875 gmalloc (size_t size)
877 bytes_used += size;
878 return xmalloc (size);
881 /* Cover function to xcalloc to record bytes allocated. */
883 static void *
884 gcalloc (size_t nelem, size_t elsize)
886 bytes_used += nelem * elsize;
887 return xcalloc (nelem, elsize);
890 /* Cover function to xrealloc.
891 We don't record the additional size since we don't know it.
892 It won't affect memory usage stats much anyway. */
894 static void *
895 grealloc (void *ptr, size_t size)
897 return xrealloc (ptr, size);
900 /* Cover function to obstack_alloc. */
902 static void *
903 gcse_alloc (unsigned long size)
905 bytes_used += size;
906 return obstack_alloc (&gcse_obstack, size);
909 /* Allocate memory for the cuid mapping array,
910 and reg/memory set tracking tables.
912 This is called at the start of each pass. */
914 static void
915 alloc_gcse_mem (void)
917 int i;
918 basic_block bb;
919 rtx insn;
921 /* Find the largest UID and create a mapping from UIDs to CUIDs.
922 CUIDs are like UIDs except they increase monotonically, have no gaps,
923 and only apply to real insns.
924 (Actually, there are gaps, for insn that are not inside a basic block.
925 but we should never see those anyway, so this is OK.) */
927 max_uid = get_max_uid ();
928 uid_cuid = gcalloc (max_uid + 1, sizeof (int));
929 i = 0;
930 FOR_EACH_BB (bb)
931 FOR_BB_INSNS (bb, insn)
933 if (INSN_P (insn))
934 uid_cuid[INSN_UID (insn)] = i++;
935 else
936 uid_cuid[INSN_UID (insn)] = i;
939 max_cuid = i;
941 /* Allocate vars to track sets of regs. */
942 reg_set_bitmap = BITMAP_ALLOC (NULL);
944 /* Allocate vars to track sets of regs, memory per block. */
945 reg_set_in_block = sbitmap_vector_alloc (last_basic_block, max_gcse_regno);
946 /* Allocate array to keep a list of insns which modify memory in each
947 basic block. */
948 modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
949 canon_modify_mem_list = gcalloc (last_basic_block, sizeof (rtx));
950 modify_mem_list_set = BITMAP_ALLOC (NULL);
951 blocks_with_calls = BITMAP_ALLOC (NULL);
954 /* Free memory allocated by alloc_gcse_mem. */
956 static void
957 free_gcse_mem (void)
959 free (uid_cuid);
961 BITMAP_FREE (reg_set_bitmap);
963 sbitmap_vector_free (reg_set_in_block);
964 free_modify_mem_tables ();
965 BITMAP_FREE (modify_mem_list_set);
966 BITMAP_FREE (blocks_with_calls);
969 /* Compute the local properties of each recorded expression.
971 Local properties are those that are defined by the block, irrespective of
972 other blocks.
974 An expression is transparent in a block if its operands are not modified
975 in the block.
977 An expression is computed (locally available) in a block if it is computed
978 at least once and expression would contain the same value if the
979 computation was moved to the end of the block.
981 An expression is locally anticipatable in a block if it is computed at
982 least once and expression would contain the same value if the computation
983 was moved to the beginning of the block.
985 We call this routine for cprop, pre and code hoisting. They all compute
986 basically the same information and thus can easily share this code.
988 TRANSP, COMP, and ANTLOC are destination sbitmaps for recording local
989 properties. If NULL, then it is not necessary to compute or record that
990 particular property.
992 TABLE controls which hash table to look at. If it is set hash table,
993 additionally, TRANSP is computed as ~TRANSP, since this is really cprop's
994 ABSALTERED. */
996 static void
997 compute_local_properties (sbitmap *transp, sbitmap *comp, sbitmap *antloc,
998 struct hash_table *table)
1000 unsigned int i;
1002 /* Initialize any bitmaps that were passed in. */
1003 if (transp)
1005 if (table->set_p)
1006 sbitmap_vector_zero (transp, last_basic_block);
1007 else
1008 sbitmap_vector_ones (transp, last_basic_block);
1011 if (comp)
1012 sbitmap_vector_zero (comp, last_basic_block);
1013 if (antloc)
1014 sbitmap_vector_zero (antloc, last_basic_block);
1016 for (i = 0; i < table->size; i++)
1018 struct expr *expr;
1020 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
1022 int indx = expr->bitmap_index;
1023 struct occr *occr;
1025 /* The expression is transparent in this block if it is not killed.
1026 We start by assuming all are transparent [none are killed], and
1027 then reset the bits for those that are. */
1028 if (transp)
1029 compute_transp (expr->expr, indx, transp, table->set_p);
1031 /* The occurrences recorded in antic_occr are exactly those that
1032 we want to set to nonzero in ANTLOC. */
1033 if (antloc)
1034 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
1036 SET_BIT (antloc[BLOCK_NUM (occr->insn)], indx);
1038 /* While we're scanning the table, this is a good place to
1039 initialize this. */
1040 occr->deleted_p = 0;
1043 /* The occurrences recorded in avail_occr are exactly those that
1044 we want to set to nonzero in COMP. */
1045 if (comp)
1046 for (occr = expr->avail_occr; occr != NULL; occr = occr->next)
1048 SET_BIT (comp[BLOCK_NUM (occr->insn)], indx);
1050 /* While we're scanning the table, this is a good place to
1051 initialize this. */
1052 occr->copied_p = 0;
1055 /* While we're scanning the table, this is a good place to
1056 initialize this. */
1057 expr->reaching_reg = 0;
1062 /* Register set information.
1064 `reg_set_table' records where each register is set or otherwise
1065 modified. */
1067 static struct obstack reg_set_obstack;
1069 static void
1070 alloc_reg_set_mem (int n_regs)
1072 reg_set_table_size = n_regs + REG_SET_TABLE_SLOP;
1073 reg_set_table = gcalloc (reg_set_table_size, sizeof (struct reg_set *));
1075 gcc_obstack_init (&reg_set_obstack);
1078 static void
1079 free_reg_set_mem (void)
1081 free (reg_set_table);
1082 obstack_free (&reg_set_obstack, NULL);
1085 /* Record REGNO in the reg_set table. */
1087 static void
1088 record_one_set (int regno, rtx insn)
1090 /* Allocate a new reg_set element and link it onto the list. */
1091 struct reg_set *new_reg_info;
1093 /* If the table isn't big enough, enlarge it. */
1094 if (regno >= reg_set_table_size)
1096 int new_size = regno + REG_SET_TABLE_SLOP;
1098 reg_set_table = grealloc (reg_set_table,
1099 new_size * sizeof (struct reg_set *));
1100 memset (reg_set_table + reg_set_table_size, 0,
1101 (new_size - reg_set_table_size) * sizeof (struct reg_set *));
1102 reg_set_table_size = new_size;
1105 new_reg_info = obstack_alloc (&reg_set_obstack, sizeof (struct reg_set));
1106 bytes_used += sizeof (struct reg_set);
1107 new_reg_info->bb_index = BLOCK_NUM (insn);
1108 new_reg_info->next = reg_set_table[regno];
1109 reg_set_table[regno] = new_reg_info;
1112 /* Called from compute_sets via note_stores to handle one SET or CLOBBER in
1113 an insn. The DATA is really the instruction in which the SET is
1114 occurring. */
1116 static void
1117 record_set_info (rtx dest, const_rtx setter ATTRIBUTE_UNUSED, void *data)
1119 rtx record_set_insn = (rtx) data;
1121 if (REG_P (dest) && REGNO (dest) >= FIRST_PSEUDO_REGISTER)
1122 record_one_set (REGNO (dest), record_set_insn);
1125 /* Scan the function and record each set of each pseudo-register.
1127 This is called once, at the start of the gcse pass. See the comments for
1128 `reg_set_table' for further documentation. */
1130 static void
1131 compute_sets (void)
1133 basic_block bb;
1134 rtx insn;
1136 FOR_EACH_BB (bb)
1137 FOR_BB_INSNS (bb, insn)
1138 if (INSN_P (insn))
1139 note_stores (PATTERN (insn), record_set_info, insn);
1142 /* Hash table support. */
1144 struct reg_avail_info
1146 basic_block last_bb;
1147 int first_set;
1148 int last_set;
1151 static struct reg_avail_info *reg_avail_info;
1152 static basic_block current_bb;
1155 /* See whether X, the source of a set, is something we want to consider for
1156 GCSE. */
1158 static int
1159 want_to_gcse_p (rtx x)
1161 #ifdef STACK_REGS
1162 /* On register stack architectures, don't GCSE constants from the
1163 constant pool, as the benefits are often swamped by the overhead
1164 of shuffling the register stack between basic blocks. */
1165 if (IS_STACK_MODE (GET_MODE (x)))
1166 x = avoid_constant_pool_reference (x);
1167 #endif
1169 switch (GET_CODE (x))
1171 case REG:
1172 case SUBREG:
1173 case CONST_INT:
1174 case CONST_DOUBLE:
1175 case CONST_FIXED:
1176 case CONST_VECTOR:
1177 case CALL:
1178 return 0;
1180 default:
1181 return can_assign_to_reg_p (x);
1185 /* Used internally by can_assign_to_reg_p. */
1187 static GTY(()) rtx test_insn;
1189 /* Return true if we can assign X to a pseudo register. */
1191 static bool
1192 can_assign_to_reg_p (rtx x)
1194 int num_clobbers = 0;
1195 int icode;
1197 /* If this is a valid operand, we are OK. If it's VOIDmode, we aren't. */
1198 if (general_operand (x, GET_MODE (x)))
1199 return 1;
1200 else if (GET_MODE (x) == VOIDmode)
1201 return 0;
1203 /* Otherwise, check if we can make a valid insn from it. First initialize
1204 our test insn if we haven't already. */
1205 if (test_insn == 0)
1207 test_insn
1208 = make_insn_raw (gen_rtx_SET (VOIDmode,
1209 gen_rtx_REG (word_mode,
1210 FIRST_PSEUDO_REGISTER * 2),
1211 const0_rtx));
1212 NEXT_INSN (test_insn) = PREV_INSN (test_insn) = 0;
1215 /* Now make an insn like the one we would make when GCSE'ing and see if
1216 valid. */
1217 PUT_MODE (SET_DEST (PATTERN (test_insn)), GET_MODE (x));
1218 SET_SRC (PATTERN (test_insn)) = x;
1219 return ((icode = recog (PATTERN (test_insn), test_insn, &num_clobbers)) >= 0
1220 && (num_clobbers == 0 || ! added_clobbers_hard_reg_p (icode)));
1223 /* Return nonzero if the operands of expression X are unchanged from the
1224 start of INSN's basic block up to but not including INSN (if AVAIL_P == 0),
1225 or from INSN to the end of INSN's basic block (if AVAIL_P != 0). */
1227 static int
1228 oprs_unchanged_p (const_rtx x, const_rtx insn, int avail_p)
1230 int i, j;
1231 enum rtx_code code;
1232 const char *fmt;
1234 if (x == 0)
1235 return 1;
1237 code = GET_CODE (x);
1238 switch (code)
1240 case REG:
1242 struct reg_avail_info *info = &reg_avail_info[REGNO (x)];
1244 if (info->last_bb != current_bb)
1245 return 1;
1246 if (avail_p)
1247 return info->last_set < INSN_CUID (insn);
1248 else
1249 return info->first_set >= INSN_CUID (insn);
1252 case MEM:
1253 if (load_killed_in_block_p (current_bb, INSN_CUID (insn),
1254 x, avail_p))
1255 return 0;
1256 else
1257 return oprs_unchanged_p (XEXP (x, 0), insn, avail_p);
1259 case PRE_DEC:
1260 case PRE_INC:
1261 case POST_DEC:
1262 case POST_INC:
1263 case PRE_MODIFY:
1264 case POST_MODIFY:
1265 return 0;
1267 case PC:
1268 case CC0: /*FIXME*/
1269 case CONST:
1270 case CONST_INT:
1271 case CONST_DOUBLE:
1272 case CONST_FIXED:
1273 case CONST_VECTOR:
1274 case SYMBOL_REF:
1275 case LABEL_REF:
1276 case ADDR_VEC:
1277 case ADDR_DIFF_VEC:
1278 return 1;
1280 default:
1281 break;
1284 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
1286 if (fmt[i] == 'e')
1288 /* If we are about to do the last recursive call needed at this
1289 level, change it into iteration. This function is called enough
1290 to be worth it. */
1291 if (i == 0)
1292 return oprs_unchanged_p (XEXP (x, i), insn, avail_p);
1294 else if (! oprs_unchanged_p (XEXP (x, i), insn, avail_p))
1295 return 0;
1297 else if (fmt[i] == 'E')
1298 for (j = 0; j < XVECLEN (x, i); j++)
1299 if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, avail_p))
1300 return 0;
1303 return 1;
1306 /* Used for communication between mems_conflict_for_gcse_p and
1307 load_killed_in_block_p. Nonzero if mems_conflict_for_gcse_p finds a
1308 conflict between two memory references. */
1309 static int gcse_mems_conflict_p;
1311 /* Used for communication between mems_conflict_for_gcse_p and
1312 load_killed_in_block_p. A memory reference for a load instruction,
1313 mems_conflict_for_gcse_p will see if a memory store conflicts with
1314 this memory load. */
1315 static const_rtx gcse_mem_operand;
1317 /* DEST is the output of an instruction. If it is a memory reference, and
1318 possibly conflicts with the load found in gcse_mem_operand, then set
1319 gcse_mems_conflict_p to a nonzero value. */
1321 static void
1322 mems_conflict_for_gcse_p (rtx dest, const_rtx setter ATTRIBUTE_UNUSED,
1323 void *data ATTRIBUTE_UNUSED)
1325 while (GET_CODE (dest) == SUBREG
1326 || GET_CODE (dest) == ZERO_EXTRACT
1327 || GET_CODE (dest) == STRICT_LOW_PART)
1328 dest = XEXP (dest, 0);
1330 /* If DEST is not a MEM, then it will not conflict with the load. Note
1331 that function calls are assumed to clobber memory, but are handled
1332 elsewhere. */
1333 if (! MEM_P (dest))
1334 return;
1336 /* If we are setting a MEM in our list of specially recognized MEMs,
1337 don't mark as killed this time. */
1339 if (expr_equiv_p (dest, gcse_mem_operand) && pre_ldst_mems != NULL)
1341 if (!find_rtx_in_ldst (dest))
1342 gcse_mems_conflict_p = 1;
1343 return;
1346 if (true_dependence (dest, GET_MODE (dest), gcse_mem_operand,
1347 rtx_addr_varies_p))
1348 gcse_mems_conflict_p = 1;
1351 /* Return nonzero if the expression in X (a memory reference) is killed
1352 in block BB before or after the insn with the CUID in UID_LIMIT.
1353 AVAIL_P is nonzero for kills after UID_LIMIT, and zero for kills
1354 before UID_LIMIT.
1356 To check the entire block, set UID_LIMIT to max_uid + 1 and
1357 AVAIL_P to 0. */
1359 static int
1360 load_killed_in_block_p (const_basic_block bb, int uid_limit, const_rtx x, int avail_p)
1362 rtx list_entry = modify_mem_list[bb->index];
1364 /* If this is a readonly then we aren't going to be changing it. */
1365 if (MEM_READONLY_P (x))
1366 return 0;
1368 while (list_entry)
1370 rtx setter;
1371 /* Ignore entries in the list that do not apply. */
1372 if ((avail_p
1373 && INSN_CUID (XEXP (list_entry, 0)) < uid_limit)
1374 || (! avail_p
1375 && INSN_CUID (XEXP (list_entry, 0)) > uid_limit))
1377 list_entry = XEXP (list_entry, 1);
1378 continue;
1381 setter = XEXP (list_entry, 0);
1383 /* If SETTER is a call everything is clobbered. Note that calls
1384 to pure functions are never put on the list, so we need not
1385 worry about them. */
1386 if (CALL_P (setter))
1387 return 1;
1389 /* SETTER must be an INSN of some kind that sets memory. Call
1390 note_stores to examine each hunk of memory that is modified.
1392 The note_stores interface is pretty limited, so we have to
1393 communicate via global variables. Yuk. */
1394 gcse_mem_operand = x;
1395 gcse_mems_conflict_p = 0;
1396 note_stores (PATTERN (setter), mems_conflict_for_gcse_p, NULL);
1397 if (gcse_mems_conflict_p)
1398 return 1;
1399 list_entry = XEXP (list_entry, 1);
1401 return 0;
1404 /* Return nonzero if the operands of expression X are unchanged from
1405 the start of INSN's basic block up to but not including INSN. */
1407 static int
1408 oprs_anticipatable_p (const_rtx x, const_rtx insn)
1410 return oprs_unchanged_p (x, insn, 0);
1413 /* Return nonzero if the operands of expression X are unchanged from
1414 INSN to the end of INSN's basic block. */
1416 static int
1417 oprs_available_p (const_rtx x, const_rtx insn)
1419 return oprs_unchanged_p (x, insn, 1);
1422 /* Hash expression X.
1424 MODE is only used if X is a CONST_INT. DO_NOT_RECORD_P is a boolean
1425 indicating if a volatile operand is found or if the expression contains
1426 something we don't want to insert in the table. HASH_TABLE_SIZE is
1427 the current size of the hash table to be probed. */
1429 static unsigned int
1430 hash_expr (const_rtx x, enum machine_mode mode, int *do_not_record_p,
1431 int hash_table_size)
1433 unsigned int hash;
1435 *do_not_record_p = 0;
1437 hash = hash_rtx (x, mode, do_not_record_p,
1438 NULL, /*have_reg_qty=*/false);
1439 return hash % hash_table_size;
1442 /* Hash a set of register REGNO.
1444 Sets are hashed on the register that is set. This simplifies the PRE copy
1445 propagation code.
1447 ??? May need to make things more elaborate. Later, as necessary. */
1449 static unsigned int
1450 hash_set (int regno, int hash_table_size)
1452 unsigned int hash;
1454 hash = regno;
1455 return hash % hash_table_size;
1458 /* Return nonzero if exp1 is equivalent to exp2. */
1460 static int
1461 expr_equiv_p (const_rtx x, const_rtx y)
1463 return exp_equiv_p (x, y, 0, true);
1466 /* Insert expression X in INSN in the hash TABLE.
1467 If it is already present, record it as the last occurrence in INSN's
1468 basic block.
1470 MODE is the mode of the value X is being stored into.
1471 It is only used if X is a CONST_INT.
1473 ANTIC_P is nonzero if X is an anticipatable expression.
1474 AVAIL_P is nonzero if X is an available expression. */
1476 static void
1477 insert_expr_in_table (rtx x, enum machine_mode mode, rtx insn, int antic_p,
1478 int avail_p, struct hash_table *table)
1480 int found, do_not_record_p;
1481 unsigned int hash;
1482 struct expr *cur_expr, *last_expr = NULL;
1483 struct occr *antic_occr, *avail_occr;
1485 hash = hash_expr (x, mode, &do_not_record_p, table->size);
1487 /* Do not insert expression in table if it contains volatile operands,
1488 or if hash_expr determines the expression is something we don't want
1489 to or can't handle. */
1490 if (do_not_record_p)
1491 return;
1493 cur_expr = table->table[hash];
1494 found = 0;
1496 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
1498 /* If the expression isn't found, save a pointer to the end of
1499 the list. */
1500 last_expr = cur_expr;
1501 cur_expr = cur_expr->next_same_hash;
1504 if (! found)
1506 cur_expr = gcse_alloc (sizeof (struct expr));
1507 bytes_used += sizeof (struct expr);
1508 if (table->table[hash] == NULL)
1509 /* This is the first pattern that hashed to this index. */
1510 table->table[hash] = cur_expr;
1511 else
1512 /* Add EXPR to end of this hash chain. */
1513 last_expr->next_same_hash = cur_expr;
1515 /* Set the fields of the expr element. */
1516 cur_expr->expr = x;
1517 cur_expr->bitmap_index = table->n_elems++;
1518 cur_expr->next_same_hash = NULL;
1519 cur_expr->antic_occr = NULL;
1520 cur_expr->avail_occr = NULL;
1523 /* Now record the occurrence(s). */
1524 if (antic_p)
1526 antic_occr = cur_expr->antic_occr;
1528 if (antic_occr && BLOCK_NUM (antic_occr->insn) != BLOCK_NUM (insn))
1529 antic_occr = NULL;
1531 if (antic_occr)
1532 /* Found another instance of the expression in the same basic block.
1533 Prefer the currently recorded one. We want the first one in the
1534 block and the block is scanned from start to end. */
1535 ; /* nothing to do */
1536 else
1538 /* First occurrence of this expression in this basic block. */
1539 antic_occr = gcse_alloc (sizeof (struct occr));
1540 bytes_used += sizeof (struct occr);
1541 antic_occr->insn = insn;
1542 antic_occr->next = cur_expr->antic_occr;
1543 antic_occr->deleted_p = 0;
1544 cur_expr->antic_occr = antic_occr;
1548 if (avail_p)
1550 avail_occr = cur_expr->avail_occr;
1552 if (avail_occr && BLOCK_NUM (avail_occr->insn) == BLOCK_NUM (insn))
1554 /* Found another instance of the expression in the same basic block.
1555 Prefer this occurrence to the currently recorded one. We want
1556 the last one in the block and the block is scanned from start
1557 to end. */
1558 avail_occr->insn = insn;
1560 else
1562 /* First occurrence of this expression in this basic block. */
1563 avail_occr = gcse_alloc (sizeof (struct occr));
1564 bytes_used += sizeof (struct occr);
1565 avail_occr->insn = insn;
1566 avail_occr->next = cur_expr->avail_occr;
1567 avail_occr->deleted_p = 0;
1568 cur_expr->avail_occr = avail_occr;
1573 /* Insert pattern X in INSN in the hash table.
1574 X is a SET of a reg to either another reg or a constant.
1575 If it is already present, record it as the last occurrence in INSN's
1576 basic block. */
1578 static void
1579 insert_set_in_table (rtx x, rtx insn, struct hash_table *table)
1581 int found;
1582 unsigned int hash;
1583 struct expr *cur_expr, *last_expr = NULL;
1584 struct occr *cur_occr;
1586 gcc_assert (GET_CODE (x) == SET && REG_P (SET_DEST (x)));
1588 hash = hash_set (REGNO (SET_DEST (x)), table->size);
1590 cur_expr = table->table[hash];
1591 found = 0;
1593 while (cur_expr && 0 == (found = expr_equiv_p (cur_expr->expr, x)))
1595 /* If the expression isn't found, save a pointer to the end of
1596 the list. */
1597 last_expr = cur_expr;
1598 cur_expr = cur_expr->next_same_hash;
1601 if (! found)
1603 cur_expr = gcse_alloc (sizeof (struct expr));
1604 bytes_used += sizeof (struct expr);
1605 if (table->table[hash] == NULL)
1606 /* This is the first pattern that hashed to this index. */
1607 table->table[hash] = cur_expr;
1608 else
1609 /* Add EXPR to end of this hash chain. */
1610 last_expr->next_same_hash = cur_expr;
1612 /* Set the fields of the expr element.
1613 We must copy X because it can be modified when copy propagation is
1614 performed on its operands. */
1615 cur_expr->expr = copy_rtx (x);
1616 cur_expr->bitmap_index = table->n_elems++;
1617 cur_expr->next_same_hash = NULL;
1618 cur_expr->antic_occr = NULL;
1619 cur_expr->avail_occr = NULL;
1622 /* Now record the occurrence. */
1623 cur_occr = cur_expr->avail_occr;
1625 if (cur_occr && BLOCK_NUM (cur_occr->insn) == BLOCK_NUM (insn))
1627 /* Found another instance of the expression in the same basic block.
1628 Prefer this occurrence to the currently recorded one. We want
1629 the last one in the block and the block is scanned from start
1630 to end. */
1631 cur_occr->insn = insn;
1633 else
1635 /* First occurrence of this expression in this basic block. */
1636 cur_occr = gcse_alloc (sizeof (struct occr));
1637 bytes_used += sizeof (struct occr);
1639 cur_occr->insn = insn;
1640 cur_occr->next = cur_expr->avail_occr;
1641 cur_occr->deleted_p = 0;
1642 cur_expr->avail_occr = cur_occr;
1646 /* Determine whether the rtx X should be treated as a constant for
1647 the purposes of GCSE's constant propagation. */
1649 static bool
1650 gcse_constant_p (const_rtx x)
1652 /* Consider a COMPARE of two integers constant. */
1653 if (GET_CODE (x) == COMPARE
1654 && GET_CODE (XEXP (x, 0)) == CONST_INT
1655 && GET_CODE (XEXP (x, 1)) == CONST_INT)
1656 return true;
1658 /* Consider a COMPARE of the same registers is a constant
1659 if they are not floating point registers. */
1660 if (GET_CODE(x) == COMPARE
1661 && REG_P (XEXP (x, 0)) && REG_P (XEXP (x, 1))
1662 && REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 1))
1663 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 0)))
1664 && ! FLOAT_MODE_P (GET_MODE (XEXP (x, 1))))
1665 return true;
1667 return CONSTANT_P (x);
1670 /* Scan pattern PAT of INSN and add an entry to the hash TABLE (set or
1671 expression one). */
1673 static void
1674 hash_scan_set (rtx pat, rtx insn, struct hash_table *table)
1676 rtx src = SET_SRC (pat);
1677 rtx dest = SET_DEST (pat);
1678 rtx note;
1680 if (GET_CODE (src) == CALL)
1681 hash_scan_call (src, insn, table);
1683 else if (REG_P (dest))
1685 unsigned int regno = REGNO (dest);
1686 rtx tmp;
1688 /* See if a REG_NOTE shows this equivalent to a simpler expression.
1689 This allows us to do a single GCSE pass and still eliminate
1690 redundant constants, addresses or other expressions that are
1691 constructed with multiple instructions. */
1692 note = find_reg_equal_equiv_note (insn);
1693 if (note != 0
1694 && (table->set_p
1695 ? gcse_constant_p (XEXP (note, 0))
1696 : want_to_gcse_p (XEXP (note, 0))))
1697 src = XEXP (note, 0), pat = gen_rtx_SET (VOIDmode, dest, src);
1699 /* Only record sets of pseudo-regs in the hash table. */
1700 if (! table->set_p
1701 && regno >= FIRST_PSEUDO_REGISTER
1702 /* Don't GCSE something if we can't do a reg/reg copy. */
1703 && can_copy_p (GET_MODE (dest))
1704 /* GCSE commonly inserts instruction after the insn. We can't
1705 do that easily for EH_REGION notes so disable GCSE on these
1706 for now. */
1707 && !find_reg_note (insn, REG_EH_REGION, NULL_RTX)
1708 /* Is SET_SRC something we want to gcse? */
1709 && want_to_gcse_p (src)
1710 /* Don't CSE a nop. */
1711 && ! set_noop_p (pat)
1712 /* Don't GCSE if it has attached REG_EQUIV note.
1713 At this point this only function parameters should have
1714 REG_EQUIV notes and if the argument slot is used somewhere
1715 explicitly, it means address of parameter has been taken,
1716 so we should not extend the lifetime of the pseudo. */
1717 && (note == NULL_RTX || ! MEM_P (XEXP (note, 0))))
1719 /* An expression is not anticipatable if its operands are
1720 modified before this insn or if this is not the only SET in
1721 this insn. The latter condition does not have to mean that
1722 SRC itself is not anticipatable, but we just will not be
1723 able to handle code motion of insns with multiple sets. */
1724 int antic_p = oprs_anticipatable_p (src, insn)
1725 && !multiple_sets (insn);
1726 /* An expression is not available if its operands are
1727 subsequently modified, including this insn. It's also not
1728 available if this is a branch, because we can't insert
1729 a set after the branch. */
1730 int avail_p = (oprs_available_p (src, insn)
1731 && ! JUMP_P (insn));
1733 insert_expr_in_table (src, GET_MODE (dest), insn, antic_p, avail_p, table);
1736 /* Record sets for constant/copy propagation. */
1737 else if (table->set_p
1738 && regno >= FIRST_PSEUDO_REGISTER
1739 && ((REG_P (src)
1740 && REGNO (src) >= FIRST_PSEUDO_REGISTER
1741 && can_copy_p (GET_MODE (dest))
1742 && REGNO (src) != regno)
1743 || gcse_constant_p (src))
1744 /* A copy is not available if its src or dest is subsequently
1745 modified. Here we want to search from INSN+1 on, but
1746 oprs_available_p searches from INSN on. */
1747 && (insn == BB_END (BLOCK_FOR_INSN (insn))
1748 || (tmp = next_nonnote_insn (insn)) == NULL_RTX
1749 || BLOCK_FOR_INSN (tmp) != BLOCK_FOR_INSN (insn)
1750 || oprs_available_p (pat, tmp)))
1751 insert_set_in_table (pat, insn, table);
1753 /* In case of store we want to consider the memory value as available in
1754 the REG stored in that memory. This makes it possible to remove
1755 redundant loads from due to stores to the same location. */
1756 else if (flag_gcse_las && REG_P (src) && MEM_P (dest))
1758 unsigned int regno = REGNO (src);
1760 /* Do not do this for constant/copy propagation. */
1761 if (! table->set_p
1762 /* Only record sets of pseudo-regs in the hash table. */
1763 && regno >= FIRST_PSEUDO_REGISTER
1764 /* Don't GCSE something if we can't do a reg/reg copy. */
1765 && can_copy_p (GET_MODE (src))
1766 /* GCSE commonly inserts instruction after the insn. We can't
1767 do that easily for EH_REGION notes so disable GCSE on these
1768 for now. */
1769 && ! find_reg_note (insn, REG_EH_REGION, NULL_RTX)
1770 /* Is SET_DEST something we want to gcse? */
1771 && want_to_gcse_p (dest)
1772 /* Don't CSE a nop. */
1773 && ! set_noop_p (pat)
1774 /* Don't GCSE if it has attached REG_EQUIV note.
1775 At this point this only function parameters should have
1776 REG_EQUIV notes and if the argument slot is used somewhere
1777 explicitly, it means address of parameter has been taken,
1778 so we should not extend the lifetime of the pseudo. */
1779 && ((note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) == 0
1780 || ! MEM_P (XEXP (note, 0))))
1782 /* Stores are never anticipatable. */
1783 int antic_p = 0;
1784 /* An expression is not available if its operands are
1785 subsequently modified, including this insn. It's also not
1786 available if this is a branch, because we can't insert
1787 a set after the branch. */
1788 int avail_p = oprs_available_p (dest, insn)
1789 && ! JUMP_P (insn);
1791 /* Record the memory expression (DEST) in the hash table. */
1792 insert_expr_in_table (dest, GET_MODE (dest), insn,
1793 antic_p, avail_p, table);
1798 static void
1799 hash_scan_clobber (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
1800 struct hash_table *table ATTRIBUTE_UNUSED)
1802 /* Currently nothing to do. */
1805 static void
1806 hash_scan_call (rtx x ATTRIBUTE_UNUSED, rtx insn ATTRIBUTE_UNUSED,
1807 struct hash_table *table ATTRIBUTE_UNUSED)
1809 /* Currently nothing to do. */
1812 /* Process INSN and add hash table entries as appropriate.
1814 Only available expressions that set a single pseudo-reg are recorded.
1816 Single sets in a PARALLEL could be handled, but it's an extra complication
1817 that isn't dealt with right now. The trick is handling the CLOBBERs that
1818 are also in the PARALLEL. Later.
1820 If SET_P is nonzero, this is for the assignment hash table,
1821 otherwise it is for the expression hash table.
1822 If IN_LIBCALL_BLOCK nonzero, we are in a libcall block, and should
1823 not record any expressions. */
1825 static void
1826 hash_scan_insn (rtx insn, struct hash_table *table, int in_libcall_block)
1828 rtx pat = PATTERN (insn);
1829 int i;
1831 if (in_libcall_block)
1832 return;
1834 /* Pick out the sets of INSN and for other forms of instructions record
1835 what's been modified. */
1837 if (GET_CODE (pat) == SET)
1838 hash_scan_set (pat, insn, table);
1839 else if (GET_CODE (pat) == PARALLEL)
1840 for (i = 0; i < XVECLEN (pat, 0); i++)
1842 rtx x = XVECEXP (pat, 0, i);
1844 if (GET_CODE (x) == SET)
1845 hash_scan_set (x, insn, table);
1846 else if (GET_CODE (x) == CLOBBER)
1847 hash_scan_clobber (x, insn, table);
1848 else if (GET_CODE (x) == CALL)
1849 hash_scan_call (x, insn, table);
1852 else if (GET_CODE (pat) == CLOBBER)
1853 hash_scan_clobber (pat, insn, table);
1854 else if (GET_CODE (pat) == CALL)
1855 hash_scan_call (pat, insn, table);
1858 static void
1859 dump_hash_table (FILE *file, const char *name, struct hash_table *table)
1861 int i;
1862 /* Flattened out table, so it's printed in proper order. */
1863 struct expr **flat_table;
1864 unsigned int *hash_val;
1865 struct expr *expr;
1867 flat_table = xcalloc (table->n_elems, sizeof (struct expr *));
1868 hash_val = xmalloc (table->n_elems * sizeof (unsigned int));
1870 for (i = 0; i < (int) table->size; i++)
1871 for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash)
1873 flat_table[expr->bitmap_index] = expr;
1874 hash_val[expr->bitmap_index] = i;
1877 fprintf (file, "%s hash table (%d buckets, %d entries)\n",
1878 name, table->size, table->n_elems);
1880 for (i = 0; i < (int) table->n_elems; i++)
1881 if (flat_table[i] != 0)
1883 expr = flat_table[i];
1884 fprintf (file, "Index %d (hash value %d)\n ",
1885 expr->bitmap_index, hash_val[i]);
1886 print_rtl (file, expr->expr);
1887 fprintf (file, "\n");
1890 fprintf (file, "\n");
1892 free (flat_table);
1893 free (hash_val);
1896 /* Record register first/last/block set information for REGNO in INSN.
1898 first_set records the first place in the block where the register
1899 is set and is used to compute "anticipatability".
1901 last_set records the last place in the block where the register
1902 is set and is used to compute "availability".
1904 last_bb records the block for which first_set and last_set are
1905 valid, as a quick test to invalidate them.
1907 reg_set_in_block records whether the register is set in the block
1908 and is used to compute "transparency". */
1910 static void
1911 record_last_reg_set_info (rtx insn, int regno)
1913 struct reg_avail_info *info = &reg_avail_info[regno];
1914 int cuid = INSN_CUID (insn);
1916 info->last_set = cuid;
1917 if (info->last_bb != current_bb)
1919 info->last_bb = current_bb;
1920 info->first_set = cuid;
1921 SET_BIT (reg_set_in_block[current_bb->index], regno);
1926 /* Record all of the canonicalized MEMs of record_last_mem_set_info's insn.
1927 Note we store a pair of elements in the list, so they have to be
1928 taken off pairwise. */
1930 static void
1931 canon_list_insert (rtx dest ATTRIBUTE_UNUSED, const_rtx unused1 ATTRIBUTE_UNUSED,
1932 void * v_insn)
1934 rtx dest_addr, insn;
1935 int bb;
1937 while (GET_CODE (dest) == SUBREG
1938 || GET_CODE (dest) == ZERO_EXTRACT
1939 || GET_CODE (dest) == STRICT_LOW_PART)
1940 dest = XEXP (dest, 0);
1942 /* If DEST is not a MEM, then it will not conflict with a load. Note
1943 that function calls are assumed to clobber memory, but are handled
1944 elsewhere. */
1946 if (! MEM_P (dest))
1947 return;
1949 dest_addr = get_addr (XEXP (dest, 0));
1950 dest_addr = canon_rtx (dest_addr);
1951 insn = (rtx) v_insn;
1952 bb = BLOCK_NUM (insn);
1954 canon_modify_mem_list[bb] =
1955 alloc_EXPR_LIST (VOIDmode, dest_addr, canon_modify_mem_list[bb]);
1956 canon_modify_mem_list[bb] =
1957 alloc_EXPR_LIST (VOIDmode, dest, canon_modify_mem_list[bb]);
1960 /* Record memory modification information for INSN. We do not actually care
1961 about the memory location(s) that are set, or even how they are set (consider
1962 a CALL_INSN). We merely need to record which insns modify memory. */
1964 static void
1965 record_last_mem_set_info (rtx insn)
1967 int bb = BLOCK_NUM (insn);
1969 /* load_killed_in_block_p will handle the case of calls clobbering
1970 everything. */
1971 modify_mem_list[bb] = alloc_INSN_LIST (insn, modify_mem_list[bb]);
1972 bitmap_set_bit (modify_mem_list_set, bb);
1974 if (CALL_P (insn))
1976 /* Note that traversals of this loop (other than for free-ing)
1977 will break after encountering a CALL_INSN. So, there's no
1978 need to insert a pair of items, as canon_list_insert does. */
1979 canon_modify_mem_list[bb] =
1980 alloc_INSN_LIST (insn, canon_modify_mem_list[bb]);
1981 bitmap_set_bit (blocks_with_calls, bb);
1983 else
1984 note_stores (PATTERN (insn), canon_list_insert, (void*) insn);
1987 /* Called from compute_hash_table via note_stores to handle one
1988 SET or CLOBBER in an insn. DATA is really the instruction in which
1989 the SET is taking place. */
1991 static void
1992 record_last_set_info (rtx dest, const_rtx setter ATTRIBUTE_UNUSED, void *data)
1994 rtx last_set_insn = (rtx) data;
1996 if (GET_CODE (dest) == SUBREG)
1997 dest = SUBREG_REG (dest);
1999 if (REG_P (dest))
2000 record_last_reg_set_info (last_set_insn, REGNO (dest));
2001 else if (MEM_P (dest)
2002 /* Ignore pushes, they clobber nothing. */
2003 && ! push_operand (dest, GET_MODE (dest)))
2004 record_last_mem_set_info (last_set_insn);
2007 /* Top level function to create an expression or assignment hash table.
2009 Expression entries are placed in the hash table if
2010 - they are of the form (set (pseudo-reg) src),
2011 - src is something we want to perform GCSE on,
2012 - none of the operands are subsequently modified in the block
2014 Assignment entries are placed in the hash table if
2015 - they are of the form (set (pseudo-reg) src),
2016 - src is something we want to perform const/copy propagation on,
2017 - none of the operands or target are subsequently modified in the block
2019 Currently src must be a pseudo-reg or a const_int.
2021 TABLE is the table computed. */
2023 static void
2024 compute_hash_table_work (struct hash_table *table)
2026 unsigned int i;
2028 /* While we compute the hash table we also compute a bit array of which
2029 registers are set in which blocks.
2030 ??? This isn't needed during const/copy propagation, but it's cheap to
2031 compute. Later. */
2032 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
2034 /* re-Cache any INSN_LIST nodes we have allocated. */
2035 clear_modify_mem_tables ();
2036 /* Some working arrays used to track first and last set in each block. */
2037 reg_avail_info = gmalloc (max_gcse_regno * sizeof (struct reg_avail_info));
2039 for (i = 0; i < max_gcse_regno; ++i)
2040 reg_avail_info[i].last_bb = NULL;
2042 FOR_EACH_BB (current_bb)
2044 rtx insn;
2045 unsigned int regno;
2046 int in_libcall_block;
2048 /* First pass over the instructions records information used to
2049 determine when registers and memory are first and last set.
2050 ??? hard-reg reg_set_in_block computation
2051 could be moved to compute_sets since they currently don't change. */
2053 FOR_BB_INSNS (current_bb, insn)
2055 if (! INSN_P (insn))
2056 continue;
2058 if (CALL_P (insn))
2060 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
2061 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
2062 record_last_reg_set_info (insn, regno);
2064 mark_call (insn);
2067 note_stores (PATTERN (insn), record_last_set_info, insn);
2070 /* Insert implicit sets in the hash table. */
2071 if (table->set_p
2072 && implicit_sets[current_bb->index] != NULL_RTX)
2073 hash_scan_set (implicit_sets[current_bb->index],
2074 BB_HEAD (current_bb), table);
2076 /* The next pass builds the hash table. */
2077 in_libcall_block = 0;
2078 FOR_BB_INSNS (current_bb, insn)
2079 if (INSN_P (insn))
2081 if (find_reg_note (insn, REG_LIBCALL, NULL_RTX))
2082 in_libcall_block = 1;
2083 else if (table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2084 in_libcall_block = 0;
2085 hash_scan_insn (insn, table, in_libcall_block);
2086 if (!table->set_p && find_reg_note (insn, REG_RETVAL, NULL_RTX))
2087 in_libcall_block = 0;
2091 free (reg_avail_info);
2092 reg_avail_info = NULL;
2095 /* Allocate space for the set/expr hash TABLE.
2096 N_INSNS is the number of instructions in the function.
2097 It is used to determine the number of buckets to use.
2098 SET_P determines whether set or expression table will
2099 be created. */
2101 static void
2102 alloc_hash_table (int n_insns, struct hash_table *table, int set_p)
2104 int n;
2106 table->size = n_insns / 4;
2107 if (table->size < 11)
2108 table->size = 11;
2110 /* Attempt to maintain efficient use of hash table.
2111 Making it an odd number is simplest for now.
2112 ??? Later take some measurements. */
2113 table->size |= 1;
2114 n = table->size * sizeof (struct expr *);
2115 table->table = gmalloc (n);
2116 table->set_p = set_p;
2119 /* Free things allocated by alloc_hash_table. */
2121 static void
2122 free_hash_table (struct hash_table *table)
2124 free (table->table);
2127 /* Compute the hash TABLE for doing copy/const propagation or
2128 expression hash table. */
2130 static void
2131 compute_hash_table (struct hash_table *table)
2133 /* Initialize count of number of entries in hash table. */
2134 table->n_elems = 0;
2135 memset (table->table, 0, table->size * sizeof (struct expr *));
2137 compute_hash_table_work (table);
2140 /* Expression tracking support. */
2142 /* Lookup REGNO in the set TABLE. The result is a pointer to the
2143 table entry, or NULL if not found. */
2145 static struct expr *
2146 lookup_set (unsigned int regno, struct hash_table *table)
2148 unsigned int hash = hash_set (regno, table->size);
2149 struct expr *expr;
2151 expr = table->table[hash];
2153 while (expr && REGNO (SET_DEST (expr->expr)) != regno)
2154 expr = expr->next_same_hash;
2156 return expr;
2159 /* Return the next entry for REGNO in list EXPR. */
2161 static struct expr *
2162 next_set (unsigned int regno, struct expr *expr)
2165 expr = expr->next_same_hash;
2166 while (expr && REGNO (SET_DEST (expr->expr)) != regno);
2168 return expr;
2171 /* Like free_INSN_LIST_list or free_EXPR_LIST_list, except that the node
2172 types may be mixed. */
2174 static void
2175 free_insn_expr_list_list (rtx *listp)
2177 rtx list, next;
2179 for (list = *listp; list ; list = next)
2181 next = XEXP (list, 1);
2182 if (GET_CODE (list) == EXPR_LIST)
2183 free_EXPR_LIST_node (list);
2184 else
2185 free_INSN_LIST_node (list);
2188 *listp = NULL;
2191 /* Clear canon_modify_mem_list and modify_mem_list tables. */
2192 static void
2193 clear_modify_mem_tables (void)
2195 unsigned i;
2196 bitmap_iterator bi;
2198 EXECUTE_IF_SET_IN_BITMAP (modify_mem_list_set, 0, i, bi)
2200 free_INSN_LIST_list (modify_mem_list + i);
2201 free_insn_expr_list_list (canon_modify_mem_list + i);
2203 bitmap_clear (modify_mem_list_set);
2204 bitmap_clear (blocks_with_calls);
2207 /* Release memory used by modify_mem_list_set. */
2209 static void
2210 free_modify_mem_tables (void)
2212 clear_modify_mem_tables ();
2213 free (modify_mem_list);
2214 free (canon_modify_mem_list);
2215 modify_mem_list = 0;
2216 canon_modify_mem_list = 0;
2219 /* Reset tables used to keep track of what's still available [since the
2220 start of the block]. */
2222 static void
2223 reset_opr_set_tables (void)
2225 /* Maintain a bitmap of which regs have been set since beginning of
2226 the block. */
2227 CLEAR_REG_SET (reg_set_bitmap);
2229 /* Also keep a record of the last instruction to modify memory.
2230 For now this is very trivial, we only record whether any memory
2231 location has been modified. */
2232 clear_modify_mem_tables ();
2235 /* Return nonzero if the operands of X are not set before INSN in
2236 INSN's basic block. */
2238 static int
2239 oprs_not_set_p (const_rtx x, const_rtx insn)
2241 int i, j;
2242 enum rtx_code code;
2243 const char *fmt;
2245 if (x == 0)
2246 return 1;
2248 code = GET_CODE (x);
2249 switch (code)
2251 case PC:
2252 case CC0:
2253 case CONST:
2254 case CONST_INT:
2255 case CONST_DOUBLE:
2256 case CONST_FIXED:
2257 case CONST_VECTOR:
2258 case SYMBOL_REF:
2259 case LABEL_REF:
2260 case ADDR_VEC:
2261 case ADDR_DIFF_VEC:
2262 return 1;
2264 case MEM:
2265 if (load_killed_in_block_p (BLOCK_FOR_INSN (insn),
2266 INSN_CUID (insn), x, 0))
2267 return 0;
2268 else
2269 return oprs_not_set_p (XEXP (x, 0), insn);
2271 case REG:
2272 return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x));
2274 default:
2275 break;
2278 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2280 if (fmt[i] == 'e')
2282 /* If we are about to do the last recursive call
2283 needed at this level, change it into iteration.
2284 This function is called enough to be worth it. */
2285 if (i == 0)
2286 return oprs_not_set_p (XEXP (x, i), insn);
2288 if (! oprs_not_set_p (XEXP (x, i), insn))
2289 return 0;
2291 else if (fmt[i] == 'E')
2292 for (j = 0; j < XVECLEN (x, i); j++)
2293 if (! oprs_not_set_p (XVECEXP (x, i, j), insn))
2294 return 0;
2297 return 1;
2300 /* Mark things set by a CALL. */
2302 static void
2303 mark_call (rtx insn)
2305 if (! CONST_OR_PURE_CALL_P (insn))
2306 record_last_mem_set_info (insn);
2309 /* Mark things set by a SET. */
2311 static void
2312 mark_set (rtx pat, rtx insn)
2314 rtx dest = SET_DEST (pat);
2316 while (GET_CODE (dest) == SUBREG
2317 || GET_CODE (dest) == ZERO_EXTRACT
2318 || GET_CODE (dest) == STRICT_LOW_PART)
2319 dest = XEXP (dest, 0);
2321 if (REG_P (dest))
2322 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (dest));
2323 else if (MEM_P (dest))
2324 record_last_mem_set_info (insn);
2326 if (GET_CODE (SET_SRC (pat)) == CALL)
2327 mark_call (insn);
2330 /* Record things set by a CLOBBER. */
2332 static void
2333 mark_clobber (rtx pat, rtx insn)
2335 rtx clob = XEXP (pat, 0);
2337 while (GET_CODE (clob) == SUBREG || GET_CODE (clob) == STRICT_LOW_PART)
2338 clob = XEXP (clob, 0);
2340 if (REG_P (clob))
2341 SET_REGNO_REG_SET (reg_set_bitmap, REGNO (clob));
2342 else
2343 record_last_mem_set_info (insn);
2346 /* Record things set by INSN.
2347 This data is used by oprs_not_set_p. */
2349 static void
2350 mark_oprs_set (rtx insn)
2352 rtx pat = PATTERN (insn);
2353 int i;
2355 if (GET_CODE (pat) == SET)
2356 mark_set (pat, insn);
2357 else if (GET_CODE (pat) == PARALLEL)
2358 for (i = 0; i < XVECLEN (pat, 0); i++)
2360 rtx x = XVECEXP (pat, 0, i);
2362 if (GET_CODE (x) == SET)
2363 mark_set (x, insn);
2364 else if (GET_CODE (x) == CLOBBER)
2365 mark_clobber (x, insn);
2366 else if (GET_CODE (x) == CALL)
2367 mark_call (insn);
2370 else if (GET_CODE (pat) == CLOBBER)
2371 mark_clobber (pat, insn);
2372 else if (GET_CODE (pat) == CALL)
2373 mark_call (insn);
2377 /* Compute copy/constant propagation working variables. */
2379 /* Local properties of assignments. */
2380 static sbitmap *cprop_pavloc;
2381 static sbitmap *cprop_absaltered;
2383 /* Global properties of assignments (computed from the local properties). */
2384 static sbitmap *cprop_avin;
2385 static sbitmap *cprop_avout;
2387 /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of
2388 basic blocks. N_SETS is the number of sets. */
2390 static void
2391 alloc_cprop_mem (int n_blocks, int n_sets)
2393 cprop_pavloc = sbitmap_vector_alloc (n_blocks, n_sets);
2394 cprop_absaltered = sbitmap_vector_alloc (n_blocks, n_sets);
2396 cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets);
2397 cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets);
2400 /* Free vars used by copy/const propagation. */
2402 static void
2403 free_cprop_mem (void)
2405 sbitmap_vector_free (cprop_pavloc);
2406 sbitmap_vector_free (cprop_absaltered);
2407 sbitmap_vector_free (cprop_avin);
2408 sbitmap_vector_free (cprop_avout);
2411 /* For each block, compute whether X is transparent. X is either an
2412 expression or an assignment [though we don't care which, for this context
2413 an assignment is treated as an expression]. For each block where an
2414 element of X is modified, set (SET_P == 1) or reset (SET_P == 0) the INDX
2415 bit in BMAP. */
2417 static void
2418 compute_transp (const_rtx x, int indx, sbitmap *bmap, int set_p)
2420 int i, j;
2421 basic_block bb;
2422 enum rtx_code code;
2423 reg_set *r;
2424 const char *fmt;
2426 /* repeat is used to turn tail-recursion into iteration since GCC
2427 can't do it when there's no return value. */
2428 repeat:
2430 if (x == 0)
2431 return;
2433 code = GET_CODE (x);
2434 switch (code)
2436 case REG:
2437 if (set_p)
2439 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
2441 FOR_EACH_BB (bb)
2442 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
2443 SET_BIT (bmap[bb->index], indx);
2445 else
2447 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
2448 SET_BIT (bmap[r->bb_index], indx);
2451 else
2453 if (REGNO (x) < FIRST_PSEUDO_REGISTER)
2455 FOR_EACH_BB (bb)
2456 if (TEST_BIT (reg_set_in_block[bb->index], REGNO (x)))
2457 RESET_BIT (bmap[bb->index], indx);
2459 else
2461 for (r = reg_set_table[REGNO (x)]; r != NULL; r = r->next)
2462 RESET_BIT (bmap[r->bb_index], indx);
2466 return;
2468 case MEM:
2469 if (! MEM_READONLY_P (x))
2471 bitmap_iterator bi;
2472 unsigned bb_index;
2474 /* First handle all the blocks with calls. We don't need to
2475 do any list walking for them. */
2476 EXECUTE_IF_SET_IN_BITMAP (blocks_with_calls, 0, bb_index, bi)
2478 if (set_p)
2479 SET_BIT (bmap[bb_index], indx);
2480 else
2481 RESET_BIT (bmap[bb_index], indx);
2484 /* Now iterate over the blocks which have memory modifications
2485 but which do not have any calls. */
2486 EXECUTE_IF_AND_COMPL_IN_BITMAP (modify_mem_list_set,
2487 blocks_with_calls,
2488 0, bb_index, bi)
2490 rtx list_entry = canon_modify_mem_list[bb_index];
2492 while (list_entry)
2494 rtx dest, dest_addr;
2496 /* LIST_ENTRY must be an INSN of some kind that sets memory.
2497 Examine each hunk of memory that is modified. */
2499 dest = XEXP (list_entry, 0);
2500 list_entry = XEXP (list_entry, 1);
2501 dest_addr = XEXP (list_entry, 0);
2503 if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
2504 x, rtx_addr_varies_p))
2506 if (set_p)
2507 SET_BIT (bmap[bb_index], indx);
2508 else
2509 RESET_BIT (bmap[bb_index], indx);
2510 break;
2512 list_entry = XEXP (list_entry, 1);
2517 x = XEXP (x, 0);
2518 goto repeat;
2520 case PC:
2521 case CC0: /*FIXME*/
2522 case CONST:
2523 case CONST_INT:
2524 case CONST_DOUBLE:
2525 case CONST_FIXED:
2526 case CONST_VECTOR:
2527 case SYMBOL_REF:
2528 case LABEL_REF:
2529 case ADDR_VEC:
2530 case ADDR_DIFF_VEC:
2531 return;
2533 default:
2534 break;
2537 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2539 if (fmt[i] == 'e')
2541 /* If we are about to do the last recursive call
2542 needed at this level, change it into iteration.
2543 This function is called enough to be worth it. */
2544 if (i == 0)
2546 x = XEXP (x, i);
2547 goto repeat;
2550 compute_transp (XEXP (x, i), indx, bmap, set_p);
2552 else if (fmt[i] == 'E')
2553 for (j = 0; j < XVECLEN (x, i); j++)
2554 compute_transp (XVECEXP (x, i, j), indx, bmap, set_p);
2558 /* Top level routine to do the dataflow analysis needed by copy/const
2559 propagation. */
2561 static void
2562 compute_cprop_data (void)
2564 compute_local_properties (cprop_absaltered, cprop_pavloc, NULL, &set_hash_table);
2565 compute_available (cprop_pavloc, cprop_absaltered,
2566 cprop_avout, cprop_avin);
2569 /* Copy/constant propagation. */
2571 /* Maximum number of register uses in an insn that we handle. */
2572 #define MAX_USES 8
2574 /* Table of uses found in an insn.
2575 Allocated statically to avoid alloc/free complexity and overhead. */
2576 static struct reg_use reg_use_table[MAX_USES];
2578 /* Index into `reg_use_table' while building it. */
2579 static int reg_use_count;
2581 /* Set up a list of register numbers used in INSN. The found uses are stored
2582 in `reg_use_table'. `reg_use_count' is initialized to zero before entry,
2583 and contains the number of uses in the table upon exit.
2585 ??? If a register appears multiple times we will record it multiple times.
2586 This doesn't hurt anything but it will slow things down. */
2588 static void
2589 find_used_regs (rtx *xptr, void *data ATTRIBUTE_UNUSED)
2591 int i, j;
2592 enum rtx_code code;
2593 const char *fmt;
2594 rtx x = *xptr;
2596 /* repeat is used to turn tail-recursion into iteration since GCC
2597 can't do it when there's no return value. */
2598 repeat:
2599 if (x == 0)
2600 return;
2602 code = GET_CODE (x);
2603 if (REG_P (x))
2605 if (reg_use_count == MAX_USES)
2606 return;
2608 reg_use_table[reg_use_count].reg_rtx = x;
2609 reg_use_count++;
2612 /* Recursively scan the operands of this expression. */
2614 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
2616 if (fmt[i] == 'e')
2618 /* If we are about to do the last recursive call
2619 needed at this level, change it into iteration.
2620 This function is called enough to be worth it. */
2621 if (i == 0)
2623 x = XEXP (x, 0);
2624 goto repeat;
2627 find_used_regs (&XEXP (x, i), data);
2629 else if (fmt[i] == 'E')
2630 for (j = 0; j < XVECLEN (x, i); j++)
2631 find_used_regs (&XVECEXP (x, i, j), data);
2635 /* Try to replace all non-SET_DEST occurrences of FROM in INSN with TO.
2636 Returns nonzero is successful. */
2638 static int
2639 try_replace_reg (rtx from, rtx to, rtx insn)
2641 rtx note = find_reg_equal_equiv_note (insn);
2642 rtx src = 0;
2643 int success = 0;
2644 rtx set = single_set (insn);
2646 /* Usually we substitute easy stuff, so we won't copy everything.
2647 We however need to take care to not duplicate non-trivial CONST
2648 expressions. */
2649 to = copy_rtx (to);
2651 validate_replace_src_group (from, to, insn);
2652 if (num_changes_pending () && apply_change_group ())
2653 success = 1;
2655 /* Try to simplify SET_SRC if we have substituted a constant. */
2656 if (success && set && CONSTANT_P (to))
2658 src = simplify_rtx (SET_SRC (set));
2660 if (src)
2661 validate_change (insn, &SET_SRC (set), src, 0);
2664 /* If there is already a REG_EQUAL note, update the expression in it
2665 with our replacement. */
2666 if (note != 0 && REG_NOTE_KIND (note) == REG_EQUAL)
2667 set_unique_reg_note (insn, REG_EQUAL,
2668 simplify_replace_rtx (XEXP (note, 0), from,
2669 copy_rtx (to)));
2670 if (!success && set && reg_mentioned_p (from, SET_SRC (set)))
2672 /* If above failed and this is a single set, try to simplify the source of
2673 the set given our substitution. We could perhaps try this for multiple
2674 SETs, but it probably won't buy us anything. */
2675 src = simplify_replace_rtx (SET_SRC (set), from, to);
2677 if (!rtx_equal_p (src, SET_SRC (set))
2678 && validate_change (insn, &SET_SRC (set), src, 0))
2679 success = 1;
2681 /* If we've failed to do replacement, have a single SET, don't already
2682 have a note, and have no special SET, add a REG_EQUAL note to not
2683 lose information. */
2684 if (!success && note == 0 && set != 0
2685 && GET_CODE (SET_DEST (set)) != ZERO_EXTRACT
2686 && GET_CODE (SET_DEST (set)) != STRICT_LOW_PART)
2687 note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src));
2690 /* REG_EQUAL may get simplified into register.
2691 We don't allow that. Remove that note. This code ought
2692 not to happen, because previous code ought to synthesize
2693 reg-reg move, but be on the safe side. */
2694 if (note && REG_NOTE_KIND (note) == REG_EQUAL && REG_P (XEXP (note, 0)))
2695 remove_note (insn, note);
2697 return success;
2700 /* Find a set of REGNOs that are available on entry to INSN's block. Returns
2701 NULL no such set is found. */
2703 static struct expr *
2704 find_avail_set (int regno, rtx insn)
2706 /* SET1 contains the last set found that can be returned to the caller for
2707 use in a substitution. */
2708 struct expr *set1 = 0;
2710 /* Loops are not possible here. To get a loop we would need two sets
2711 available at the start of the block containing INSN. i.e. we would
2712 need two sets like this available at the start of the block:
2714 (set (reg X) (reg Y))
2715 (set (reg Y) (reg X))
2717 This can not happen since the set of (reg Y) would have killed the
2718 set of (reg X) making it unavailable at the start of this block. */
2719 while (1)
2721 rtx src;
2722 struct expr *set = lookup_set (regno, &set_hash_table);
2724 /* Find a set that is available at the start of the block
2725 which contains INSN. */
2726 while (set)
2728 if (TEST_BIT (cprop_avin[BLOCK_NUM (insn)], set->bitmap_index))
2729 break;
2730 set = next_set (regno, set);
2733 /* If no available set was found we've reached the end of the
2734 (possibly empty) copy chain. */
2735 if (set == 0)
2736 break;
2738 gcc_assert (GET_CODE (set->expr) == SET);
2740 src = SET_SRC (set->expr);
2742 /* We know the set is available.
2743 Now check that SRC is ANTLOC (i.e. none of the source operands
2744 have changed since the start of the block).
2746 If the source operand changed, we may still use it for the next
2747 iteration of this loop, but we may not use it for substitutions. */
2749 if (gcse_constant_p (src) || oprs_not_set_p (src, insn))
2750 set1 = set;
2752 /* If the source of the set is anything except a register, then
2753 we have reached the end of the copy chain. */
2754 if (! REG_P (src))
2755 break;
2757 /* Follow the copy chain, i.e. start another iteration of the loop
2758 and see if we have an available copy into SRC. */
2759 regno = REGNO (src);
2762 /* SET1 holds the last set that was available and anticipatable at
2763 INSN. */
2764 return set1;
2767 /* Subroutine of cprop_insn that tries to propagate constants into
2768 JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL
2769 it is the instruction that immediately precedes JUMP, and must be a
2770 single SET of a register. FROM is what we will try to replace,
2771 SRC is the constant we will try to substitute for it. Returns nonzero
2772 if a change was made. */
2774 static int
2775 cprop_jump (basic_block bb, rtx setcc, rtx jump, rtx from, rtx src)
2777 rtx new, set_src, note_src;
2778 rtx set = pc_set (jump);
2779 rtx note = find_reg_equal_equiv_note (jump);
2781 if (note)
2783 note_src = XEXP (note, 0);
2784 if (GET_CODE (note_src) == EXPR_LIST)
2785 note_src = NULL_RTX;
2787 else note_src = NULL_RTX;
2789 /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */
2790 set_src = note_src ? note_src : SET_SRC (set);
2792 /* First substitute the SETCC condition into the JUMP instruction,
2793 then substitute that given values into this expanded JUMP. */
2794 if (setcc != NULL_RTX
2795 && !modified_between_p (from, setcc, jump)
2796 && !modified_between_p (src, setcc, jump))
2798 rtx setcc_src;
2799 rtx setcc_set = single_set (setcc);
2800 rtx setcc_note = find_reg_equal_equiv_note (setcc);
2801 setcc_src = (setcc_note && GET_CODE (XEXP (setcc_note, 0)) != EXPR_LIST)
2802 ? XEXP (setcc_note, 0) : SET_SRC (setcc_set);
2803 set_src = simplify_replace_rtx (set_src, SET_DEST (setcc_set),
2804 setcc_src);
2806 else
2807 setcc = NULL_RTX;
2809 new = simplify_replace_rtx (set_src, from, src);
2811 /* If no simplification can be made, then try the next register. */
2812 if (rtx_equal_p (new, SET_SRC (set)))
2813 return 0;
2815 /* If this is now a no-op delete it, otherwise this must be a valid insn. */
2816 if (new == pc_rtx)
2817 delete_insn (jump);
2818 else
2820 /* Ensure the value computed inside the jump insn to be equivalent
2821 to one computed by setcc. */
2822 if (setcc && modified_in_p (new, setcc))
2823 return 0;
2824 if (! validate_change (jump, &SET_SRC (set), new, 0))
2826 /* When (some) constants are not valid in a comparison, and there
2827 are two registers to be replaced by constants before the entire
2828 comparison can be folded into a constant, we need to keep
2829 intermediate information in REG_EQUAL notes. For targets with
2830 separate compare insns, such notes are added by try_replace_reg.
2831 When we have a combined compare-and-branch instruction, however,
2832 we need to attach a note to the branch itself to make this
2833 optimization work. */
2835 if (!rtx_equal_p (new, note_src))
2836 set_unique_reg_note (jump, REG_EQUAL, copy_rtx (new));
2837 return 0;
2840 /* Remove REG_EQUAL note after simplification. */
2841 if (note_src)
2842 remove_note (jump, note);
2845 #ifdef HAVE_cc0
2846 /* Delete the cc0 setter. */
2847 if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc))))
2848 delete_insn (setcc);
2849 #endif
2851 run_jump_opt_after_gcse = 1;
2853 global_const_prop_count++;
2854 if (dump_file != NULL)
2856 fprintf (dump_file,
2857 "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with constant ",
2858 REGNO (from), INSN_UID (jump));
2859 print_rtl (dump_file, src);
2860 fprintf (dump_file, "\n");
2862 purge_dead_edges (bb);
2864 /* If a conditional jump has been changed into unconditional jump, remove
2865 the jump and make the edge fallthru - this is always called in
2866 cfglayout mode. */
2867 if (new != pc_rtx && simplejump_p (jump))
2869 edge e;
2870 edge_iterator ei;
2872 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ei_next (&ei))
2873 if (e->dest != EXIT_BLOCK_PTR
2874 && BB_HEAD (e->dest) == JUMP_LABEL (jump))
2876 e->flags |= EDGE_FALLTHRU;
2877 break;
2879 delete_insn (jump);
2882 return 1;
2885 static bool
2886 constprop_register (rtx insn, rtx from, rtx to, bool alter_jumps)
2888 rtx sset;
2890 /* Check for reg or cc0 setting instructions followed by
2891 conditional branch instructions first. */
2892 if (alter_jumps
2893 && (sset = single_set (insn)) != NULL
2894 && NEXT_INSN (insn)
2895 && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn)))
2897 rtx dest = SET_DEST (sset);
2898 if ((REG_P (dest) || CC0_P (dest))
2899 && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), from, to))
2900 return 1;
2903 /* Handle normal insns next. */
2904 if (NONJUMP_INSN_P (insn)
2905 && try_replace_reg (from, to, insn))
2906 return 1;
2908 /* Try to propagate a CONST_INT into a conditional jump.
2909 We're pretty specific about what we will handle in this
2910 code, we can extend this as necessary over time.
2912 Right now the insn in question must look like
2913 (set (pc) (if_then_else ...)) */
2914 else if (alter_jumps && any_condjump_p (insn) && onlyjump_p (insn))
2915 return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, to);
2916 return 0;
2919 /* Perform constant and copy propagation on INSN.
2920 The result is nonzero if a change was made. */
2922 static int
2923 cprop_insn (rtx insn, int alter_jumps)
2925 struct reg_use *reg_used;
2926 int changed = 0;
2927 rtx note;
2929 if (!INSN_P (insn))
2930 return 0;
2932 reg_use_count = 0;
2933 note_uses (&PATTERN (insn), find_used_regs, NULL);
2935 note = find_reg_equal_equiv_note (insn);
2937 /* We may win even when propagating constants into notes. */
2938 if (note)
2939 find_used_regs (&XEXP (note, 0), NULL);
2941 for (reg_used = &reg_use_table[0]; reg_use_count > 0;
2942 reg_used++, reg_use_count--)
2944 unsigned int regno = REGNO (reg_used->reg_rtx);
2945 rtx pat, src;
2946 struct expr *set;
2948 /* Ignore registers created by GCSE.
2949 We do this because ... */
2950 if (regno >= max_gcse_regno)
2951 continue;
2953 /* If the register has already been set in this block, there's
2954 nothing we can do. */
2955 if (! oprs_not_set_p (reg_used->reg_rtx, insn))
2956 continue;
2958 /* Find an assignment that sets reg_used and is available
2959 at the start of the block. */
2960 set = find_avail_set (regno, insn);
2961 if (! set)
2962 continue;
2964 pat = set->expr;
2965 /* ??? We might be able to handle PARALLELs. Later. */
2966 gcc_assert (GET_CODE (pat) == SET);
2968 src = SET_SRC (pat);
2970 /* Constant propagation. */
2971 if (gcse_constant_p (src))
2973 if (constprop_register (insn, reg_used->reg_rtx, src, alter_jumps))
2975 changed = 1;
2976 global_const_prop_count++;
2977 if (dump_file != NULL)
2979 fprintf (dump_file, "GLOBAL CONST-PROP: Replacing reg %d in ", regno);
2980 fprintf (dump_file, "insn %d with constant ", INSN_UID (insn));
2981 print_rtl (dump_file, src);
2982 fprintf (dump_file, "\n");
2984 if (INSN_DELETED_P (insn))
2985 return 1;
2988 else if (REG_P (src)
2989 && REGNO (src) >= FIRST_PSEUDO_REGISTER
2990 && REGNO (src) != regno)
2992 if (try_replace_reg (reg_used->reg_rtx, src, insn))
2994 changed = 1;
2995 global_copy_prop_count++;
2996 if (dump_file != NULL)
2998 fprintf (dump_file, "GLOBAL COPY-PROP: Replacing reg %d in insn %d",
2999 regno, INSN_UID (insn));
3000 fprintf (dump_file, " with reg %d\n", REGNO (src));
3003 /* The original insn setting reg_used may or may not now be
3004 deletable. We leave the deletion to flow. */
3005 /* FIXME: If it turns out that the insn isn't deletable,
3006 then we may have unnecessarily extended register lifetimes
3007 and made things worse. */
3012 return changed;
3015 /* Like find_used_regs, but avoid recording uses that appear in
3016 input-output contexts such as zero_extract or pre_dec. This
3017 restricts the cases we consider to those for which local cprop
3018 can legitimately make replacements. */
3020 static void
3021 local_cprop_find_used_regs (rtx *xptr, void *data)
3023 rtx x = *xptr;
3025 if (x == 0)
3026 return;
3028 switch (GET_CODE (x))
3030 case ZERO_EXTRACT:
3031 case SIGN_EXTRACT:
3032 case STRICT_LOW_PART:
3033 return;
3035 case PRE_DEC:
3036 case PRE_INC:
3037 case POST_DEC:
3038 case POST_INC:
3039 case PRE_MODIFY:
3040 case POST_MODIFY:
3041 /* Can only legitimately appear this early in the context of
3042 stack pushes for function arguments, but handle all of the
3043 codes nonetheless. */
3044 return;
3046 case SUBREG:
3047 /* Setting a subreg of a register larger than word_mode leaves
3048 the non-written words unchanged. */
3049 if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD)
3050 return;
3051 break;
3053 default:
3054 break;
3057 find_used_regs (xptr, data);
3060 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3061 their REG_EQUAL notes need updating. */
3063 static bool
3064 do_local_cprop (rtx x, rtx insn, bool alter_jumps, rtx *libcall_sp)
3066 rtx newreg = NULL, newcnst = NULL;
3068 /* Rule out USE instructions and ASM statements as we don't want to
3069 change the hard registers mentioned. */
3070 if (REG_P (x)
3071 && (REGNO (x) >= FIRST_PSEUDO_REGISTER
3072 || (GET_CODE (PATTERN (insn)) != USE
3073 && asm_noperands (PATTERN (insn)) < 0)))
3075 cselib_val *val = cselib_lookup (x, GET_MODE (x), 0);
3076 struct elt_loc_list *l;
3078 if (!val)
3079 return false;
3080 for (l = val->locs; l; l = l->next)
3082 rtx this_rtx = l->loc;
3083 rtx note;
3085 /* Don't CSE non-constant values out of libcall blocks. */
3086 if (l->in_libcall && ! CONSTANT_P (this_rtx))
3087 continue;
3089 if (gcse_constant_p (this_rtx))
3090 newcnst = this_rtx;
3091 if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER
3092 /* Don't copy propagate if it has attached REG_EQUIV note.
3093 At this point this only function parameters should have
3094 REG_EQUIV notes and if the argument slot is used somewhere
3095 explicitly, it means address of parameter has been taken,
3096 so we should not extend the lifetime of the pseudo. */
3097 && (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX))
3098 || ! MEM_P (XEXP (note, 0))))
3099 newreg = this_rtx;
3101 if (newcnst && constprop_register (insn, x, newcnst, alter_jumps))
3103 /* If we find a case where we can't fix the retval REG_EQUAL notes
3104 match the new register, we either have to abandon this replacement
3105 or fix delete_trivially_dead_insns to preserve the setting insn,
3106 or make it delete the REG_EQUAL note, and fix up all passes that
3107 require the REG_EQUAL note there. */
3108 bool adjusted;
3110 adjusted = adjust_libcall_notes (x, newcnst, insn, libcall_sp);
3111 gcc_assert (adjusted);
3113 if (dump_file != NULL)
3115 fprintf (dump_file, "LOCAL CONST-PROP: Replacing reg %d in ",
3116 REGNO (x));
3117 fprintf (dump_file, "insn %d with constant ",
3118 INSN_UID (insn));
3119 print_rtl (dump_file, newcnst);
3120 fprintf (dump_file, "\n");
3122 local_const_prop_count++;
3123 return true;
3125 else if (newreg && newreg != x && try_replace_reg (x, newreg, insn))
3127 adjust_libcall_notes (x, newreg, insn, libcall_sp);
3128 if (dump_file != NULL)
3130 fprintf (dump_file,
3131 "LOCAL COPY-PROP: Replacing reg %d in insn %d",
3132 REGNO (x), INSN_UID (insn));
3133 fprintf (dump_file, " with reg %d\n", REGNO (newreg));
3135 local_copy_prop_count++;
3136 return true;
3139 return false;
3142 /* LIBCALL_SP is a zero-terminated array of insns at the end of a libcall;
3143 their REG_EQUAL notes need updating to reflect that OLDREG has been
3144 replaced with NEWVAL in INSN. Return true if all substitutions could
3145 be made. */
3146 static bool
3147 adjust_libcall_notes (rtx oldreg, rtx newval, rtx insn, rtx *libcall_sp)
3149 rtx end;
3151 while ((end = *libcall_sp++))
3153 rtx note = find_reg_equal_equiv_note (end);
3155 if (! note)
3156 continue;
3158 if (REG_P (newval))
3160 if (reg_set_between_p (newval, PREV_INSN (insn), end))
3164 note = find_reg_equal_equiv_note (end);
3165 if (! note)
3166 continue;
3167 if (reg_mentioned_p (newval, XEXP (note, 0)))
3168 return false;
3170 while ((end = *libcall_sp++));
3171 return true;
3174 XEXP (note, 0) = simplify_replace_rtx (XEXP (note, 0), oldreg, newval);
3175 df_notes_rescan (end);
3176 insn = end;
3178 return true;
3181 #define MAX_NESTED_LIBCALLS 9
3183 /* Do local const/copy propagation (i.e. within each basic block).
3184 If ALTER_JUMPS is true, allow propagating into jump insns, which
3185 could modify the CFG. */
3187 static void
3188 local_cprop_pass (bool alter_jumps)
3190 basic_block bb;
3191 rtx insn;
3192 struct reg_use *reg_used;
3193 rtx libcall_stack[MAX_NESTED_LIBCALLS + 1], *libcall_sp;
3194 bool changed = false;
3196 cselib_init (false);
3197 libcall_sp = &libcall_stack[MAX_NESTED_LIBCALLS];
3198 *libcall_sp = 0;
3199 FOR_EACH_BB (bb)
3201 FOR_BB_INSNS (bb, insn)
3203 if (INSN_P (insn))
3205 rtx note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
3207 if (note)
3209 gcc_assert (libcall_sp != libcall_stack);
3210 *--libcall_sp = XEXP (note, 0);
3212 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
3213 if (note)
3214 libcall_sp++;
3215 note = find_reg_equal_equiv_note (insn);
3218 reg_use_count = 0;
3219 note_uses (&PATTERN (insn), local_cprop_find_used_regs,
3220 NULL);
3221 if (note)
3222 local_cprop_find_used_regs (&XEXP (note, 0), NULL);
3224 for (reg_used = &reg_use_table[0]; reg_use_count > 0;
3225 reg_used++, reg_use_count--)
3227 if (do_local_cprop (reg_used->reg_rtx, insn, alter_jumps,
3228 libcall_sp))
3230 changed = true;
3231 break;
3234 if (INSN_DELETED_P (insn))
3235 break;
3237 while (reg_use_count);
3239 cselib_process_insn (insn);
3242 /* Forget everything at the end of a basic block. Make sure we are
3243 not inside a libcall, they should never cross basic blocks. */
3244 cselib_clear_table ();
3245 gcc_assert (libcall_sp == &libcall_stack[MAX_NESTED_LIBCALLS]);
3248 cselib_finish ();
3250 /* Global analysis may get into infinite loops for unreachable blocks. */
3251 if (changed && alter_jumps)
3253 delete_unreachable_blocks ();
3254 free_reg_set_mem ();
3255 alloc_reg_set_mem (max_reg_num ());
3256 compute_sets ();
3260 /* Forward propagate copies. This includes copies and constants. Return
3261 nonzero if a change was made. */
3263 static int
3264 cprop (int alter_jumps)
3266 int changed;
3267 basic_block bb;
3268 rtx insn;
3270 /* Note we start at block 1. */
3271 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
3273 if (dump_file != NULL)
3274 fprintf (dump_file, "\n");
3275 return 0;
3278 changed = 0;
3279 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, next_bb)
3281 /* Reset tables used to keep track of what's still valid [since the
3282 start of the block]. */
3283 reset_opr_set_tables ();
3285 FOR_BB_INSNS (bb, insn)
3286 if (INSN_P (insn))
3288 changed |= cprop_insn (insn, alter_jumps);
3290 /* Keep track of everything modified by this insn. */
3291 /* ??? Need to be careful w.r.t. mods done to INSN. Don't
3292 call mark_oprs_set if we turned the insn into a NOTE. */
3293 if (! NOTE_P (insn))
3294 mark_oprs_set (insn);
3298 if (dump_file != NULL)
3299 fprintf (dump_file, "\n");
3301 return changed;
3304 /* Similar to get_condition, only the resulting condition must be
3305 valid at JUMP, instead of at EARLIEST.
3307 This differs from noce_get_condition in ifcvt.c in that we prefer not to
3308 settle for the condition variable in the jump instruction being integral.
3309 We prefer to be able to record the value of a user variable, rather than
3310 the value of a temporary used in a condition. This could be solved by
3311 recording the value of *every* register scanned by canonicalize_condition,
3312 but this would require some code reorganization. */
3315 fis_get_condition (rtx jump)
3317 return get_condition (jump, NULL, false, true);
3320 /* Check the comparison COND to see if we can safely form an implicit set from
3321 it. COND is either an EQ or NE comparison. */
3323 static bool
3324 implicit_set_cond_p (const_rtx cond)
3326 const enum machine_mode mode = GET_MODE (XEXP (cond, 0));
3327 const_rtx cst = XEXP (cond, 1);
3329 /* We can't perform this optimization if either operand might be or might
3330 contain a signed zero. */
3331 if (HONOR_SIGNED_ZEROS (mode))
3333 /* It is sufficient to check if CST is or contains a zero. We must
3334 handle float, complex, and vector. If any subpart is a zero, then
3335 the optimization can't be performed. */
3336 /* ??? The complex and vector checks are not implemented yet. We just
3337 always return zero for them. */
3338 if (GET_CODE (cst) == CONST_DOUBLE)
3340 REAL_VALUE_TYPE d;
3341 REAL_VALUE_FROM_CONST_DOUBLE (d, cst);
3342 if (REAL_VALUES_EQUAL (d, dconst0))
3343 return 0;
3345 else
3346 return 0;
3349 return gcse_constant_p (cst);
3352 /* Find the implicit sets of a function. An "implicit set" is a constraint
3353 on the value of a variable, implied by a conditional jump. For example,
3354 following "if (x == 2)", the then branch may be optimized as though the
3355 conditional performed an "explicit set", in this example, "x = 2". This
3356 function records the set patterns that are implicit at the start of each
3357 basic block. */
3359 static void
3360 find_implicit_sets (void)
3362 basic_block bb, dest;
3363 unsigned int count;
3364 rtx cond, new;
3366 count = 0;
3367 FOR_EACH_BB (bb)
3368 /* Check for more than one successor. */
3369 if (EDGE_COUNT (bb->succs) > 1)
3371 cond = fis_get_condition (BB_END (bb));
3373 if (cond
3374 && (GET_CODE (cond) == EQ || GET_CODE (cond) == NE)
3375 && REG_P (XEXP (cond, 0))
3376 && REGNO (XEXP (cond, 0)) >= FIRST_PSEUDO_REGISTER
3377 && implicit_set_cond_p (cond))
3379 dest = GET_CODE (cond) == EQ ? BRANCH_EDGE (bb)->dest
3380 : FALLTHRU_EDGE (bb)->dest;
3382 if (dest && single_pred_p (dest)
3383 && dest != EXIT_BLOCK_PTR)
3385 new = gen_rtx_SET (VOIDmode, XEXP (cond, 0),
3386 XEXP (cond, 1));
3387 implicit_sets[dest->index] = new;
3388 if (dump_file)
3390 fprintf(dump_file, "Implicit set of reg %d in ",
3391 REGNO (XEXP (cond, 0)));
3392 fprintf(dump_file, "basic block %d\n", dest->index);
3394 count++;
3399 if (dump_file)
3400 fprintf (dump_file, "Found %d implicit sets\n", count);
3403 /* Perform one copy/constant propagation pass.
3404 PASS is the pass count. If CPROP_JUMPS is true, perform constant
3405 propagation into conditional jumps. If BYPASS_JUMPS is true,
3406 perform conditional jump bypassing optimizations. */
3408 static int
3409 one_cprop_pass (int pass, bool cprop_jumps, bool bypass_jumps)
3411 int changed = 0;
3413 global_const_prop_count = local_const_prop_count = 0;
3414 global_copy_prop_count = local_copy_prop_count = 0;
3416 if (cprop_jumps)
3417 local_cprop_pass (cprop_jumps);
3419 /* Determine implicit sets. */
3420 implicit_sets = XCNEWVEC (rtx, last_basic_block);
3421 find_implicit_sets ();
3423 alloc_hash_table (max_cuid, &set_hash_table, 1);
3424 compute_hash_table (&set_hash_table);
3426 /* Free implicit_sets before peak usage. */
3427 free (implicit_sets);
3428 implicit_sets = NULL;
3430 if (dump_file)
3431 dump_hash_table (dump_file, "SET", &set_hash_table);
3432 if (set_hash_table.n_elems > 0)
3434 alloc_cprop_mem (last_basic_block, set_hash_table.n_elems);
3435 compute_cprop_data ();
3436 changed = cprop (cprop_jumps);
3437 if (bypass_jumps)
3438 changed |= bypass_conditional_jumps ();
3439 free_cprop_mem ();
3442 free_hash_table (&set_hash_table);
3444 if (dump_file)
3446 fprintf (dump_file, "CPROP of %s, pass %d: %d bytes needed, ",
3447 current_function_name (), pass, bytes_used);
3448 fprintf (dump_file, "%d local const props, %d local copy props, ",
3449 local_const_prop_count, local_copy_prop_count);
3450 fprintf (dump_file, "%d global const props, %d global copy props\n\n",
3451 global_const_prop_count, global_copy_prop_count);
3453 /* Global analysis may get into infinite loops for unreachable blocks. */
3454 if (changed && cprop_jumps)
3455 delete_unreachable_blocks ();
3457 return changed;
3460 /* Bypass conditional jumps. */
3462 /* The value of last_basic_block at the beginning of the jump_bypass
3463 pass. The use of redirect_edge_and_branch_force may introduce new
3464 basic blocks, but the data flow analysis is only valid for basic
3465 block indices less than bypass_last_basic_block. */
3467 static int bypass_last_basic_block;
3469 /* Find a set of REGNO to a constant that is available at the end of basic
3470 block BB. Returns NULL if no such set is found. Based heavily upon
3471 find_avail_set. */
3473 static struct expr *
3474 find_bypass_set (int regno, int bb)
3476 struct expr *result = 0;
3478 for (;;)
3480 rtx src;
3481 struct expr *set = lookup_set (regno, &set_hash_table);
3483 while (set)
3485 if (TEST_BIT (cprop_avout[bb], set->bitmap_index))
3486 break;
3487 set = next_set (regno, set);
3490 if (set == 0)
3491 break;
3493 gcc_assert (GET_CODE (set->expr) == SET);
3495 src = SET_SRC (set->expr);
3496 if (gcse_constant_p (src))
3497 result = set;
3499 if (! REG_P (src))
3500 break;
3502 regno = REGNO (src);
3504 return result;
3508 /* Subroutine of bypass_block that checks whether a pseudo is killed by
3509 any of the instructions inserted on an edge. Jump bypassing places
3510 condition code setters on CFG edges using insert_insn_on_edge. This
3511 function is required to check that our data flow analysis is still
3512 valid prior to commit_edge_insertions. */
3514 static bool
3515 reg_killed_on_edge (const_rtx reg, const_edge e)
3517 rtx insn;
3519 for (insn = e->insns.r; insn; insn = NEXT_INSN (insn))
3520 if (INSN_P (insn) && reg_set_p (reg, insn))
3521 return true;
3523 return false;
3526 /* Subroutine of bypass_conditional_jumps that attempts to bypass the given
3527 basic block BB which has more than one predecessor. If not NULL, SETCC
3528 is the first instruction of BB, which is immediately followed by JUMP_INSN
3529 JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB.
3530 Returns nonzero if a change was made.
3532 During the jump bypassing pass, we may place copies of SETCC instructions
3533 on CFG edges. The following routine must be careful to pay attention to
3534 these inserted insns when performing its transformations. */
3536 static int
3537 bypass_block (basic_block bb, rtx setcc, rtx jump)
3539 rtx insn, note;
3540 edge e, edest;
3541 int i, change;
3542 int may_be_loop_header;
3543 unsigned removed_p;
3544 edge_iterator ei;
3546 insn = (setcc != NULL) ? setcc : jump;
3548 /* Determine set of register uses in INSN. */
3549 reg_use_count = 0;
3550 note_uses (&PATTERN (insn), find_used_regs, NULL);
3551 note = find_reg_equal_equiv_note (insn);
3552 if (note)
3553 find_used_regs (&XEXP (note, 0), NULL);
3555 may_be_loop_header = false;
3556 FOR_EACH_EDGE (e, ei, bb->preds)
3557 if (e->flags & EDGE_DFS_BACK)
3559 may_be_loop_header = true;
3560 break;
3563 change = 0;
3564 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
3566 removed_p = 0;
3568 if (e->flags & EDGE_COMPLEX)
3570 ei_next (&ei);
3571 continue;
3574 /* We can't redirect edges from new basic blocks. */
3575 if (e->src->index >= bypass_last_basic_block)
3577 ei_next (&ei);
3578 continue;
3581 /* The irreducible loops created by redirecting of edges entering the
3582 loop from outside would decrease effectiveness of some of the following
3583 optimizations, so prevent this. */
3584 if (may_be_loop_header
3585 && !(e->flags & EDGE_DFS_BACK))
3587 ei_next (&ei);
3588 continue;
3591 for (i = 0; i < reg_use_count; i++)
3593 struct reg_use *reg_used = &reg_use_table[i];
3594 unsigned int regno = REGNO (reg_used->reg_rtx);
3595 basic_block dest, old_dest;
3596 struct expr *set;
3597 rtx src, new;
3599 if (regno >= max_gcse_regno)
3600 continue;
3602 set = find_bypass_set (regno, e->src->index);
3604 if (! set)
3605 continue;
3607 /* Check the data flow is valid after edge insertions. */
3608 if (e->insns.r && reg_killed_on_edge (reg_used->reg_rtx, e))
3609 continue;
3611 src = SET_SRC (pc_set (jump));
3613 if (setcc != NULL)
3614 src = simplify_replace_rtx (src,
3615 SET_DEST (PATTERN (setcc)),
3616 SET_SRC (PATTERN (setcc)));
3618 new = simplify_replace_rtx (src, reg_used->reg_rtx,
3619 SET_SRC (set->expr));
3621 /* Jump bypassing may have already placed instructions on
3622 edges of the CFG. We can't bypass an outgoing edge that
3623 has instructions associated with it, as these insns won't
3624 get executed if the incoming edge is redirected. */
3626 if (new == pc_rtx)
3628 edest = FALLTHRU_EDGE (bb);
3629 dest = edest->insns.r ? NULL : edest->dest;
3631 else if (GET_CODE (new) == LABEL_REF)
3633 dest = BLOCK_FOR_INSN (XEXP (new, 0));
3634 /* Don't bypass edges containing instructions. */
3635 edest = find_edge (bb, dest);
3636 if (edest && edest->insns.r)
3637 dest = NULL;
3639 else
3640 dest = NULL;
3642 /* Avoid unification of the edge with other edges from original
3643 branch. We would end up emitting the instruction on "both"
3644 edges. */
3646 if (dest && setcc && !CC0_P (SET_DEST (PATTERN (setcc)))
3647 && find_edge (e->src, dest))
3648 dest = NULL;
3650 old_dest = e->dest;
3651 if (dest != NULL
3652 && dest != old_dest
3653 && dest != EXIT_BLOCK_PTR)
3655 redirect_edge_and_branch_force (e, dest);
3657 /* Copy the register setter to the redirected edge.
3658 Don't copy CC0 setters, as CC0 is dead after jump. */
3659 if (setcc)
3661 rtx pat = PATTERN (setcc);
3662 if (!CC0_P (SET_DEST (pat)))
3663 insert_insn_on_edge (copy_insn (pat), e);
3666 if (dump_file != NULL)
3668 fprintf (dump_file, "JUMP-BYPASS: Proved reg %d "
3669 "in jump_insn %d equals constant ",
3670 regno, INSN_UID (jump));
3671 print_rtl (dump_file, SET_SRC (set->expr));
3672 fprintf (dump_file, "\nBypass edge from %d->%d to %d\n",
3673 e->src->index, old_dest->index, dest->index);
3675 change = 1;
3676 removed_p = 1;
3677 break;
3680 if (!removed_p)
3681 ei_next (&ei);
3683 return change;
3686 /* Find basic blocks with more than one predecessor that only contain a
3687 single conditional jump. If the result of the comparison is known at
3688 compile-time from any incoming edge, redirect that edge to the
3689 appropriate target. Returns nonzero if a change was made.
3691 This function is now mis-named, because we also handle indirect jumps. */
3693 static int
3694 bypass_conditional_jumps (void)
3696 basic_block bb;
3697 int changed;
3698 rtx setcc;
3699 rtx insn;
3700 rtx dest;
3702 /* Note we start at block 1. */
3703 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
3704 return 0;
3706 bypass_last_basic_block = last_basic_block;
3707 mark_dfs_back_edges ();
3709 changed = 0;
3710 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb,
3711 EXIT_BLOCK_PTR, next_bb)
3713 /* Check for more than one predecessor. */
3714 if (!single_pred_p (bb))
3716 setcc = NULL_RTX;
3717 FOR_BB_INSNS (bb, insn)
3718 if (NONJUMP_INSN_P (insn))
3720 if (setcc)
3721 break;
3722 if (GET_CODE (PATTERN (insn)) != SET)
3723 break;
3725 dest = SET_DEST (PATTERN (insn));
3726 if (REG_P (dest) || CC0_P (dest))
3727 setcc = insn;
3728 else
3729 break;
3731 else if (JUMP_P (insn))
3733 if ((any_condjump_p (insn) || computed_jump_p (insn))
3734 && onlyjump_p (insn))
3735 changed |= bypass_block (bb, setcc, insn);
3736 break;
3738 else if (INSN_P (insn))
3739 break;
3743 /* If we bypassed any register setting insns, we inserted a
3744 copy on the redirected edge. These need to be committed. */
3745 if (changed)
3746 commit_edge_insertions ();
3748 return changed;
3751 /* Compute PRE+LCM working variables. */
3753 /* Local properties of expressions. */
3754 /* Nonzero for expressions that are transparent in the block. */
3755 static sbitmap *transp;
3757 /* Nonzero for expressions that are transparent at the end of the block.
3758 This is only zero for expressions killed by abnormal critical edge
3759 created by a calls. */
3760 static sbitmap *transpout;
3762 /* Nonzero for expressions that are computed (available) in the block. */
3763 static sbitmap *comp;
3765 /* Nonzero for expressions that are locally anticipatable in the block. */
3766 static sbitmap *antloc;
3768 /* Nonzero for expressions where this block is an optimal computation
3769 point. */
3770 static sbitmap *pre_optimal;
3772 /* Nonzero for expressions which are redundant in a particular block. */
3773 static sbitmap *pre_redundant;
3775 /* Nonzero for expressions which should be inserted on a specific edge. */
3776 static sbitmap *pre_insert_map;
3778 /* Nonzero for expressions which should be deleted in a specific block. */
3779 static sbitmap *pre_delete_map;
3781 /* Contains the edge_list returned by pre_edge_lcm. */
3782 static struct edge_list *edge_list;
3784 /* Redundant insns. */
3785 static sbitmap pre_redundant_insns;
3787 /* Allocate vars used for PRE analysis. */
3789 static void
3790 alloc_pre_mem (int n_blocks, int n_exprs)
3792 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
3793 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
3794 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
3796 pre_optimal = NULL;
3797 pre_redundant = NULL;
3798 pre_insert_map = NULL;
3799 pre_delete_map = NULL;
3800 ae_kill = sbitmap_vector_alloc (n_blocks, n_exprs);
3802 /* pre_insert and pre_delete are allocated later. */
3805 /* Free vars used for PRE analysis. */
3807 static void
3808 free_pre_mem (void)
3810 sbitmap_vector_free (transp);
3811 sbitmap_vector_free (comp);
3813 /* ANTLOC and AE_KILL are freed just after pre_lcm finishes. */
3815 if (pre_optimal)
3816 sbitmap_vector_free (pre_optimal);
3817 if (pre_redundant)
3818 sbitmap_vector_free (pre_redundant);
3819 if (pre_insert_map)
3820 sbitmap_vector_free (pre_insert_map);
3821 if (pre_delete_map)
3822 sbitmap_vector_free (pre_delete_map);
3824 transp = comp = NULL;
3825 pre_optimal = pre_redundant = pre_insert_map = pre_delete_map = NULL;
3828 /* Top level routine to do the dataflow analysis needed by PRE. */
3830 static void
3831 compute_pre_data (void)
3833 sbitmap trapping_expr;
3834 basic_block bb;
3835 unsigned int ui;
3837 compute_local_properties (transp, comp, antloc, &expr_hash_table);
3838 sbitmap_vector_zero (ae_kill, last_basic_block);
3840 /* Collect expressions which might trap. */
3841 trapping_expr = sbitmap_alloc (expr_hash_table.n_elems);
3842 sbitmap_zero (trapping_expr);
3843 for (ui = 0; ui < expr_hash_table.size; ui++)
3845 struct expr *e;
3846 for (e = expr_hash_table.table[ui]; e != NULL; e = e->next_same_hash)
3847 if (may_trap_p (e->expr))
3848 SET_BIT (trapping_expr, e->bitmap_index);
3851 /* Compute ae_kill for each basic block using:
3853 ~(TRANSP | COMP)
3856 FOR_EACH_BB (bb)
3858 edge e;
3859 edge_iterator ei;
3861 /* If the current block is the destination of an abnormal edge, we
3862 kill all trapping expressions because we won't be able to properly
3863 place the instruction on the edge. So make them neither
3864 anticipatable nor transparent. This is fairly conservative. */
3865 FOR_EACH_EDGE (e, ei, bb->preds)
3866 if (e->flags & EDGE_ABNORMAL)
3868 sbitmap_difference (antloc[bb->index], antloc[bb->index], trapping_expr);
3869 sbitmap_difference (transp[bb->index], transp[bb->index], trapping_expr);
3870 break;
3873 sbitmap_a_or_b (ae_kill[bb->index], transp[bb->index], comp[bb->index]);
3874 sbitmap_not (ae_kill[bb->index], ae_kill[bb->index]);
3877 edge_list = pre_edge_lcm (expr_hash_table.n_elems, transp, comp, antloc,
3878 ae_kill, &pre_insert_map, &pre_delete_map);
3879 sbitmap_vector_free (antloc);
3880 antloc = NULL;
3881 sbitmap_vector_free (ae_kill);
3882 ae_kill = NULL;
3883 sbitmap_free (trapping_expr);
3886 /* PRE utilities */
3888 /* Return nonzero if an occurrence of expression EXPR in OCCR_BB would reach
3889 block BB.
3891 VISITED is a pointer to a working buffer for tracking which BB's have
3892 been visited. It is NULL for the top-level call.
3894 We treat reaching expressions that go through blocks containing the same
3895 reaching expression as "not reaching". E.g. if EXPR is generated in blocks
3896 2 and 3, INSN is in block 4, and 2->3->4, we treat the expression in block
3897 2 as not reaching. The intent is to improve the probability of finding
3898 only one reaching expression and to reduce register lifetimes by picking
3899 the closest such expression. */
3901 static int
3902 pre_expr_reaches_here_p_work (basic_block occr_bb, struct expr *expr, basic_block bb, char *visited)
3904 edge pred;
3905 edge_iterator ei;
3907 FOR_EACH_EDGE (pred, ei, bb->preds)
3909 basic_block pred_bb = pred->src;
3911 if (pred->src == ENTRY_BLOCK_PTR
3912 /* Has predecessor has already been visited? */
3913 || visited[pred_bb->index])
3914 ;/* Nothing to do. */
3916 /* Does this predecessor generate this expression? */
3917 else if (TEST_BIT (comp[pred_bb->index], expr->bitmap_index))
3919 /* Is this the occurrence we're looking for?
3920 Note that there's only one generating occurrence per block
3921 so we just need to check the block number. */
3922 if (occr_bb == pred_bb)
3923 return 1;
3925 visited[pred_bb->index] = 1;
3927 /* Ignore this predecessor if it kills the expression. */
3928 else if (! TEST_BIT (transp[pred_bb->index], expr->bitmap_index))
3929 visited[pred_bb->index] = 1;
3931 /* Neither gen nor kill. */
3932 else
3934 visited[pred_bb->index] = 1;
3935 if (pre_expr_reaches_here_p_work (occr_bb, expr, pred_bb, visited))
3936 return 1;
3940 /* All paths have been checked. */
3941 return 0;
3944 /* The wrapper for pre_expr_reaches_here_work that ensures that any
3945 memory allocated for that function is returned. */
3947 static int
3948 pre_expr_reaches_here_p (basic_block occr_bb, struct expr *expr, basic_block bb)
3950 int rval;
3951 char *visited = XCNEWVEC (char, last_basic_block);
3953 rval = pre_expr_reaches_here_p_work (occr_bb, expr, bb, visited);
3955 free (visited);
3956 return rval;
3960 /* Given an expr, generate RTL which we can insert at the end of a BB,
3961 or on an edge. Set the block number of any insns generated to
3962 the value of BB. */
3964 static rtx
3965 process_insert_insn (struct expr *expr)
3967 rtx reg = expr->reaching_reg;
3968 rtx exp = copy_rtx (expr->expr);
3969 rtx pat;
3971 start_sequence ();
3973 /* If the expression is something that's an operand, like a constant,
3974 just copy it to a register. */
3975 if (general_operand (exp, GET_MODE (reg)))
3976 emit_move_insn (reg, exp);
3978 /* Otherwise, make a new insn to compute this expression and make sure the
3979 insn will be recognized (this also adds any needed CLOBBERs). Copy the
3980 expression to make sure we don't have any sharing issues. */
3981 else
3983 rtx insn = emit_insn (gen_rtx_SET (VOIDmode, reg, exp));
3985 if (insn_invalid_p (insn))
3986 gcc_unreachable ();
3990 pat = get_insns ();
3991 end_sequence ();
3993 return pat;
3996 /* Add EXPR to the end of basic block BB.
3998 This is used by both the PRE and code hoisting.
4000 For PRE, we want to verify that the expr is either transparent
4001 or locally anticipatable in the target block. This check makes
4002 no sense for code hoisting. */
4004 static void
4005 insert_insn_end_basic_block (struct expr *expr, basic_block bb, int pre)
4007 rtx insn = BB_END (bb);
4008 rtx new_insn;
4009 rtx reg = expr->reaching_reg;
4010 int regno = REGNO (reg);
4011 rtx pat, pat_end;
4013 pat = process_insert_insn (expr);
4014 gcc_assert (pat && INSN_P (pat));
4016 pat_end = pat;
4017 while (NEXT_INSN (pat_end) != NULL_RTX)
4018 pat_end = NEXT_INSN (pat_end);
4020 /* If the last insn is a jump, insert EXPR in front [taking care to
4021 handle cc0, etc. properly]. Similarly we need to care trapping
4022 instructions in presence of non-call exceptions. */
4024 if (JUMP_P (insn)
4025 || (NONJUMP_INSN_P (insn)
4026 && (!single_succ_p (bb)
4027 || single_succ_edge (bb)->flags & EDGE_ABNORMAL)))
4029 #ifdef HAVE_cc0
4030 rtx note;
4031 #endif
4032 /* It should always be the case that we can put these instructions
4033 anywhere in the basic block with performing PRE optimizations.
4034 Check this. */
4035 gcc_assert (!NONJUMP_INSN_P (insn) || !pre
4036 || TEST_BIT (antloc[bb->index], expr->bitmap_index)
4037 || TEST_BIT (transp[bb->index], expr->bitmap_index));
4039 /* If this is a jump table, then we can't insert stuff here. Since
4040 we know the previous real insn must be the tablejump, we insert
4041 the new instruction just before the tablejump. */
4042 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
4043 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
4044 insn = prev_real_insn (insn);
4046 #ifdef HAVE_cc0
4047 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
4048 if cc0 isn't set. */
4049 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
4050 if (note)
4051 insn = XEXP (note, 0);
4052 else
4054 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
4055 if (maybe_cc0_setter
4056 && INSN_P (maybe_cc0_setter)
4057 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
4058 insn = maybe_cc0_setter;
4060 #endif
4061 /* FIXME: What if something in cc0/jump uses value set in new insn? */
4062 new_insn = emit_insn_before_noloc (pat, insn, bb);
4065 /* Likewise if the last insn is a call, as will happen in the presence
4066 of exception handling. */
4067 else if (CALL_P (insn)
4068 && (!single_succ_p (bb)
4069 || single_succ_edge (bb)->flags & EDGE_ABNORMAL))
4071 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
4072 we search backward and place the instructions before the first
4073 parameter is loaded. Do this for everyone for consistency and a
4074 presumption that we'll get better code elsewhere as well.
4076 It should always be the case that we can put these instructions
4077 anywhere in the basic block with performing PRE optimizations.
4078 Check this. */
4080 gcc_assert (!pre
4081 || TEST_BIT (antloc[bb->index], expr->bitmap_index)
4082 || TEST_BIT (transp[bb->index], expr->bitmap_index));
4084 /* Since different machines initialize their parameter registers
4085 in different orders, assume nothing. Collect the set of all
4086 parameter registers. */
4087 insn = find_first_parameter_load (insn, BB_HEAD (bb));
4089 /* If we found all the parameter loads, then we want to insert
4090 before the first parameter load.
4092 If we did not find all the parameter loads, then we might have
4093 stopped on the head of the block, which could be a CODE_LABEL.
4094 If we inserted before the CODE_LABEL, then we would be putting
4095 the insn in the wrong basic block. In that case, put the insn
4096 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
4097 while (LABEL_P (insn)
4098 || NOTE_INSN_BASIC_BLOCK_P (insn))
4099 insn = NEXT_INSN (insn);
4101 new_insn = emit_insn_before_noloc (pat, insn, bb);
4103 else
4104 new_insn = emit_insn_after_noloc (pat, insn, bb);
4106 while (1)
4108 if (INSN_P (pat))
4110 add_label_notes (PATTERN (pat), new_insn);
4111 note_stores (PATTERN (pat), record_set_info, pat);
4113 if (pat == pat_end)
4114 break;
4115 pat = NEXT_INSN (pat);
4118 gcse_create_count++;
4120 if (dump_file)
4122 fprintf (dump_file, "PRE/HOIST: end of bb %d, insn %d, ",
4123 bb->index, INSN_UID (new_insn));
4124 fprintf (dump_file, "copying expression %d to reg %d\n",
4125 expr->bitmap_index, regno);
4129 /* Insert partially redundant expressions on edges in the CFG to make
4130 the expressions fully redundant. */
4132 static int
4133 pre_edge_insert (struct edge_list *edge_list, struct expr **index_map)
4135 int e, i, j, num_edges, set_size, did_insert = 0;
4136 sbitmap *inserted;
4138 /* Where PRE_INSERT_MAP is nonzero, we add the expression on that edge
4139 if it reaches any of the deleted expressions. */
4141 set_size = pre_insert_map[0]->size;
4142 num_edges = NUM_EDGES (edge_list);
4143 inserted = sbitmap_vector_alloc (num_edges, expr_hash_table.n_elems);
4144 sbitmap_vector_zero (inserted, num_edges);
4146 for (e = 0; e < num_edges; e++)
4148 int indx;
4149 basic_block bb = INDEX_EDGE_PRED_BB (edge_list, e);
4151 for (i = indx = 0; i < set_size; i++, indx += SBITMAP_ELT_BITS)
4153 SBITMAP_ELT_TYPE insert = pre_insert_map[e]->elms[i];
4155 for (j = indx; insert && j < (int) expr_hash_table.n_elems; j++, insert >>= 1)
4156 if ((insert & 1) != 0 && index_map[j]->reaching_reg != NULL_RTX)
4158 struct expr *expr = index_map[j];
4159 struct occr *occr;
4161 /* Now look at each deleted occurrence of this expression. */
4162 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4164 if (! occr->deleted_p)
4165 continue;
4167 /* Insert this expression on this edge if it would
4168 reach the deleted occurrence in BB. */
4169 if (!TEST_BIT (inserted[e], j))
4171 rtx insn;
4172 edge eg = INDEX_EDGE (edge_list, e);
4174 /* We can't insert anything on an abnormal and
4175 critical edge, so we insert the insn at the end of
4176 the previous block. There are several alternatives
4177 detailed in Morgans book P277 (sec 10.5) for
4178 handling this situation. This one is easiest for
4179 now. */
4181 if (eg->flags & EDGE_ABNORMAL)
4182 insert_insn_end_basic_block (index_map[j], bb, 0);
4183 else
4185 insn = process_insert_insn (index_map[j]);
4186 insert_insn_on_edge (insn, eg);
4189 if (dump_file)
4191 fprintf (dump_file, "PRE/HOIST: edge (%d,%d), ",
4192 bb->index,
4193 INDEX_EDGE_SUCC_BB (edge_list, e)->index);
4194 fprintf (dump_file, "copy expression %d\n",
4195 expr->bitmap_index);
4198 update_ld_motion_stores (expr);
4199 SET_BIT (inserted[e], j);
4200 did_insert = 1;
4201 gcse_create_count++;
4208 sbitmap_vector_free (inserted);
4209 return did_insert;
4212 /* Copy the result of EXPR->EXPR generated by INSN to EXPR->REACHING_REG.
4213 Given "old_reg <- expr" (INSN), instead of adding after it
4214 reaching_reg <- old_reg
4215 it's better to do the following:
4216 reaching_reg <- expr
4217 old_reg <- reaching_reg
4218 because this way copy propagation can discover additional PRE
4219 opportunities. But if this fails, we try the old way.
4220 When "expr" is a store, i.e.
4221 given "MEM <- old_reg", instead of adding after it
4222 reaching_reg <- old_reg
4223 it's better to add it before as follows:
4224 reaching_reg <- old_reg
4225 MEM <- reaching_reg. */
4227 static void
4228 pre_insert_copy_insn (struct expr *expr, rtx insn)
4230 rtx reg = expr->reaching_reg;
4231 int regno = REGNO (reg);
4232 int indx = expr->bitmap_index;
4233 rtx pat = PATTERN (insn);
4234 rtx set, first_set, new_insn;
4235 rtx old_reg;
4236 int i;
4238 /* This block matches the logic in hash_scan_insn. */
4239 switch (GET_CODE (pat))
4241 case SET:
4242 set = pat;
4243 break;
4245 case PARALLEL:
4246 /* Search through the parallel looking for the set whose
4247 source was the expression that we're interested in. */
4248 first_set = NULL_RTX;
4249 set = NULL_RTX;
4250 for (i = 0; i < XVECLEN (pat, 0); i++)
4252 rtx x = XVECEXP (pat, 0, i);
4253 if (GET_CODE (x) == SET)
4255 /* If the source was a REG_EQUAL or REG_EQUIV note, we
4256 may not find an equivalent expression, but in this
4257 case the PARALLEL will have a single set. */
4258 if (first_set == NULL_RTX)
4259 first_set = x;
4260 if (expr_equiv_p (SET_SRC (x), expr->expr))
4262 set = x;
4263 break;
4268 gcc_assert (first_set);
4269 if (set == NULL_RTX)
4270 set = first_set;
4271 break;
4273 default:
4274 gcc_unreachable ();
4277 if (REG_P (SET_DEST (set)))
4279 old_reg = SET_DEST (set);
4280 /* Check if we can modify the set destination in the original insn. */
4281 if (validate_change (insn, &SET_DEST (set), reg, 0))
4283 new_insn = gen_move_insn (old_reg, reg);
4284 new_insn = emit_insn_after (new_insn, insn);
4286 /* Keep register set table up to date. */
4287 record_one_set (regno, insn);
4289 else
4291 new_insn = gen_move_insn (reg, old_reg);
4292 new_insn = emit_insn_after (new_insn, insn);
4294 /* Keep register set table up to date. */
4295 record_one_set (regno, new_insn);
4298 else /* This is possible only in case of a store to memory. */
4300 old_reg = SET_SRC (set);
4301 new_insn = gen_move_insn (reg, old_reg);
4303 /* Check if we can modify the set source in the original insn. */
4304 if (validate_change (insn, &SET_SRC (set), reg, 0))
4305 new_insn = emit_insn_before (new_insn, insn);
4306 else
4307 new_insn = emit_insn_after (new_insn, insn);
4309 /* Keep register set table up to date. */
4310 record_one_set (regno, new_insn);
4313 gcse_create_count++;
4315 if (dump_file)
4316 fprintf (dump_file,
4317 "PRE: bb %d, insn %d, copy expression %d in insn %d to reg %d\n",
4318 BLOCK_NUM (insn), INSN_UID (new_insn), indx,
4319 INSN_UID (insn), regno);
4322 /* Copy available expressions that reach the redundant expression
4323 to `reaching_reg'. */
4325 static void
4326 pre_insert_copies (void)
4328 unsigned int i, added_copy;
4329 struct expr *expr;
4330 struct occr *occr;
4331 struct occr *avail;
4333 /* For each available expression in the table, copy the result to
4334 `reaching_reg' if the expression reaches a deleted one.
4336 ??? The current algorithm is rather brute force.
4337 Need to do some profiling. */
4339 for (i = 0; i < expr_hash_table.size; i++)
4340 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
4342 /* If the basic block isn't reachable, PPOUT will be TRUE. However,
4343 we don't want to insert a copy here because the expression may not
4344 really be redundant. So only insert an insn if the expression was
4345 deleted. This test also avoids further processing if the
4346 expression wasn't deleted anywhere. */
4347 if (expr->reaching_reg == NULL)
4348 continue;
4350 /* Set when we add a copy for that expression. */
4351 added_copy = 0;
4353 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4355 if (! occr->deleted_p)
4356 continue;
4358 for (avail = expr->avail_occr; avail != NULL; avail = avail->next)
4360 rtx insn = avail->insn;
4362 /* No need to handle this one if handled already. */
4363 if (avail->copied_p)
4364 continue;
4366 /* Don't handle this one if it's a redundant one. */
4367 if (TEST_BIT (pre_redundant_insns, INSN_CUID (insn)))
4368 continue;
4370 /* Or if the expression doesn't reach the deleted one. */
4371 if (! pre_expr_reaches_here_p (BLOCK_FOR_INSN (avail->insn),
4372 expr,
4373 BLOCK_FOR_INSN (occr->insn)))
4374 continue;
4376 added_copy = 1;
4378 /* Copy the result of avail to reaching_reg. */
4379 pre_insert_copy_insn (expr, insn);
4380 avail->copied_p = 1;
4384 if (added_copy)
4385 update_ld_motion_stores (expr);
4389 /* Emit move from SRC to DEST noting the equivalence with expression computed
4390 in INSN. */
4391 static rtx
4392 gcse_emit_move_after (rtx src, rtx dest, rtx insn)
4394 rtx new;
4395 rtx set = single_set (insn), set2;
4396 rtx note;
4397 rtx eqv;
4399 /* This should never fail since we're creating a reg->reg copy
4400 we've verified to be valid. */
4402 new = emit_insn_after (gen_move_insn (dest, src), insn);
4404 /* Note the equivalence for local CSE pass. */
4405 set2 = single_set (new);
4406 if (!set2 || !rtx_equal_p (SET_DEST (set2), dest))
4407 return new;
4408 if ((note = find_reg_equal_equiv_note (insn)))
4409 eqv = XEXP (note, 0);
4410 else
4411 eqv = SET_SRC (set);
4413 set_unique_reg_note (new, REG_EQUAL, copy_insn_1 (eqv));
4415 return new;
4418 /* Delete redundant computations.
4419 Deletion is done by changing the insn to copy the `reaching_reg' of
4420 the expression into the result of the SET. It is left to later passes
4421 (cprop, cse2, flow, combine, regmove) to propagate the copy or eliminate it.
4423 Returns nonzero if a change is made. */
4425 static int
4426 pre_delete (void)
4428 unsigned int i;
4429 int changed;
4430 struct expr *expr;
4431 struct occr *occr;
4433 changed = 0;
4434 for (i = 0; i < expr_hash_table.size; i++)
4435 for (expr = expr_hash_table.table[i];
4436 expr != NULL;
4437 expr = expr->next_same_hash)
4439 int indx = expr->bitmap_index;
4441 /* We only need to search antic_occr since we require
4442 ANTLOC != 0. */
4444 for (occr = expr->antic_occr; occr != NULL; occr = occr->next)
4446 rtx insn = occr->insn;
4447 rtx set;
4448 basic_block bb = BLOCK_FOR_INSN (insn);
4450 /* We only delete insns that have a single_set. */
4451 if (TEST_BIT (pre_delete_map[bb->index], indx)
4452 && (set = single_set (insn)) != 0
4453 && dbg_cnt (pre_insn))
4455 /* Create a pseudo-reg to store the result of reaching
4456 expressions into. Get the mode for the new pseudo from
4457 the mode of the original destination pseudo. */
4458 if (expr->reaching_reg == NULL)
4459 expr->reaching_reg
4460 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
4462 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
4463 delete_insn (insn);
4464 occr->deleted_p = 1;
4465 SET_BIT (pre_redundant_insns, INSN_CUID (insn));
4466 changed = 1;
4467 gcse_subst_count++;
4469 if (dump_file)
4471 fprintf (dump_file,
4472 "PRE: redundant insn %d (expression %d) in ",
4473 INSN_UID (insn), indx);
4474 fprintf (dump_file, "bb %d, reaching reg is %d\n",
4475 bb->index, REGNO (expr->reaching_reg));
4481 return changed;
4484 /* Perform GCSE optimizations using PRE.
4485 This is called by one_pre_gcse_pass after all the dataflow analysis
4486 has been done.
4488 This is based on the original Morel-Renvoise paper Fred Chow's thesis, and
4489 lazy code motion from Knoop, Ruthing and Steffen as described in Advanced
4490 Compiler Design and Implementation.
4492 ??? A new pseudo reg is created to hold the reaching expression. The nice
4493 thing about the classical approach is that it would try to use an existing
4494 reg. If the register can't be adequately optimized [i.e. we introduce
4495 reload problems], one could add a pass here to propagate the new register
4496 through the block.
4498 ??? We don't handle single sets in PARALLELs because we're [currently] not
4499 able to copy the rest of the parallel when we insert copies to create full
4500 redundancies from partial redundancies. However, there's no reason why we
4501 can't handle PARALLELs in the cases where there are no partial
4502 redundancies. */
4504 static int
4505 pre_gcse (void)
4507 unsigned int i;
4508 int did_insert, changed;
4509 struct expr **index_map;
4510 struct expr *expr;
4512 /* Compute a mapping from expression number (`bitmap_index') to
4513 hash table entry. */
4515 index_map = XCNEWVEC (struct expr *, expr_hash_table.n_elems);
4516 for (i = 0; i < expr_hash_table.size; i++)
4517 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
4518 index_map[expr->bitmap_index] = expr;
4520 /* Reset bitmap used to track which insns are redundant. */
4521 pre_redundant_insns = sbitmap_alloc (max_cuid);
4522 sbitmap_zero (pre_redundant_insns);
4524 /* Delete the redundant insns first so that
4525 - we know what register to use for the new insns and for the other
4526 ones with reaching expressions
4527 - we know which insns are redundant when we go to create copies */
4529 changed = pre_delete ();
4530 did_insert = pre_edge_insert (edge_list, index_map);
4532 /* In other places with reaching expressions, copy the expression to the
4533 specially allocated pseudo-reg that reaches the redundant expr. */
4534 pre_insert_copies ();
4535 if (did_insert)
4537 commit_edge_insertions ();
4538 changed = 1;
4541 free (index_map);
4542 sbitmap_free (pre_redundant_insns);
4543 return changed;
4546 /* Top level routine to perform one PRE GCSE pass.
4548 Return nonzero if a change was made. */
4550 static int
4551 one_pre_gcse_pass (int pass)
4553 int changed = 0;
4555 gcse_subst_count = 0;
4556 gcse_create_count = 0;
4558 alloc_hash_table (max_cuid, &expr_hash_table, 0);
4559 add_noreturn_fake_exit_edges ();
4560 if (flag_gcse_lm)
4561 compute_ld_motion_mems ();
4563 compute_hash_table (&expr_hash_table);
4564 trim_ld_motion_mems ();
4565 if (dump_file)
4566 dump_hash_table (dump_file, "Expression", &expr_hash_table);
4568 if (expr_hash_table.n_elems > 0)
4570 alloc_pre_mem (last_basic_block, expr_hash_table.n_elems);
4571 compute_pre_data ();
4572 changed |= pre_gcse ();
4573 free_edge_list (edge_list);
4574 free_pre_mem ();
4577 free_ldst_mems ();
4578 remove_fake_exit_edges ();
4579 free_hash_table (&expr_hash_table);
4581 if (dump_file)
4583 fprintf (dump_file, "\nPRE GCSE of %s, pass %d: %d bytes needed, ",
4584 current_function_name (), pass, bytes_used);
4585 fprintf (dump_file, "%d substs, %d insns created\n",
4586 gcse_subst_count, gcse_create_count);
4589 return changed;
4592 /* If X contains any LABEL_REF's, add REG_LABEL_OPERAND notes for them
4593 to INSN. If such notes are added to an insn which references a
4594 CODE_LABEL, the LABEL_NUSES count is incremented. We have to add
4595 that note, because the following loop optimization pass requires
4596 them. */
4598 /* ??? If there was a jump optimization pass after gcse and before loop,
4599 then we would not need to do this here, because jump would add the
4600 necessary REG_LABEL_OPERAND and REG_LABEL_TARGET notes. */
4602 static void
4603 add_label_notes (rtx x, rtx insn)
4605 enum rtx_code code = GET_CODE (x);
4606 int i, j;
4607 const char *fmt;
4609 if (code == LABEL_REF && !LABEL_REF_NONLOCAL_P (x))
4611 /* This code used to ignore labels that referred to dispatch tables to
4612 avoid flow generating (slightly) worse code.
4614 We no longer ignore such label references (see LABEL_REF handling in
4615 mark_jump_label for additional information). */
4617 if (reg_mentioned_p (XEXP (x, 0), insn))
4619 /* There's no reason for current users to emit jump-insns
4620 with such a LABEL_REF, so we don't have to handle
4621 REG_LABEL_TARGET notes. */
4622 gcc_assert (!JUMP_P (insn));
4623 REG_NOTES (insn)
4624 = gen_rtx_INSN_LIST (REG_LABEL_OPERAND, XEXP (x, 0),
4625 REG_NOTES (insn));
4626 if (LABEL_P (XEXP (x, 0)))
4627 LABEL_NUSES (XEXP (x, 0))++;
4629 return;
4632 for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--)
4634 if (fmt[i] == 'e')
4635 add_label_notes (XEXP (x, i), insn);
4636 else if (fmt[i] == 'E')
4637 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
4638 add_label_notes (XVECEXP (x, i, j), insn);
4642 /* Compute transparent outgoing information for each block.
4644 An expression is transparent to an edge unless it is killed by
4645 the edge itself. This can only happen with abnormal control flow,
4646 when the edge is traversed through a call. This happens with
4647 non-local labels and exceptions.
4649 This would not be necessary if we split the edge. While this is
4650 normally impossible for abnormal critical edges, with some effort
4651 it should be possible with exception handling, since we still have
4652 control over which handler should be invoked. But due to increased
4653 EH table sizes, this may not be worthwhile. */
4655 static void
4656 compute_transpout (void)
4658 basic_block bb;
4659 unsigned int i;
4660 struct expr *expr;
4662 sbitmap_vector_ones (transpout, last_basic_block);
4664 FOR_EACH_BB (bb)
4666 /* Note that flow inserted a nop a the end of basic blocks that
4667 end in call instructions for reasons other than abnormal
4668 control flow. */
4669 if (! CALL_P (BB_END (bb)))
4670 continue;
4672 for (i = 0; i < expr_hash_table.size; i++)
4673 for (expr = expr_hash_table.table[i]; expr ; expr = expr->next_same_hash)
4674 if (MEM_P (expr->expr))
4676 if (GET_CODE (XEXP (expr->expr, 0)) == SYMBOL_REF
4677 && CONSTANT_POOL_ADDRESS_P (XEXP (expr->expr, 0)))
4678 continue;
4680 /* ??? Optimally, we would use interprocedural alias
4681 analysis to determine if this mem is actually killed
4682 by this call. */
4683 RESET_BIT (transpout[bb->index], expr->bitmap_index);
4688 /* Code Hoisting variables and subroutines. */
4690 /* Very busy expressions. */
4691 static sbitmap *hoist_vbein;
4692 static sbitmap *hoist_vbeout;
4694 /* Hoistable expressions. */
4695 static sbitmap *hoist_exprs;
4697 /* ??? We could compute post dominators and run this algorithm in
4698 reverse to perform tail merging, doing so would probably be
4699 more effective than the tail merging code in jump.c.
4701 It's unclear if tail merging could be run in parallel with
4702 code hoisting. It would be nice. */
4704 /* Allocate vars used for code hoisting analysis. */
4706 static void
4707 alloc_code_hoist_mem (int n_blocks, int n_exprs)
4709 antloc = sbitmap_vector_alloc (n_blocks, n_exprs);
4710 transp = sbitmap_vector_alloc (n_blocks, n_exprs);
4711 comp = sbitmap_vector_alloc (n_blocks, n_exprs);
4713 hoist_vbein = sbitmap_vector_alloc (n_blocks, n_exprs);
4714 hoist_vbeout = sbitmap_vector_alloc (n_blocks, n_exprs);
4715 hoist_exprs = sbitmap_vector_alloc (n_blocks, n_exprs);
4716 transpout = sbitmap_vector_alloc (n_blocks, n_exprs);
4719 /* Free vars used for code hoisting analysis. */
4721 static void
4722 free_code_hoist_mem (void)
4724 sbitmap_vector_free (antloc);
4725 sbitmap_vector_free (transp);
4726 sbitmap_vector_free (comp);
4728 sbitmap_vector_free (hoist_vbein);
4729 sbitmap_vector_free (hoist_vbeout);
4730 sbitmap_vector_free (hoist_exprs);
4731 sbitmap_vector_free (transpout);
4733 free_dominance_info (CDI_DOMINATORS);
4736 /* Compute the very busy expressions at entry/exit from each block.
4738 An expression is very busy if all paths from a given point
4739 compute the expression. */
4741 static void
4742 compute_code_hoist_vbeinout (void)
4744 int changed, passes;
4745 basic_block bb;
4747 sbitmap_vector_zero (hoist_vbeout, last_basic_block);
4748 sbitmap_vector_zero (hoist_vbein, last_basic_block);
4750 passes = 0;
4751 changed = 1;
4753 while (changed)
4755 changed = 0;
4757 /* We scan the blocks in the reverse order to speed up
4758 the convergence. */
4759 FOR_EACH_BB_REVERSE (bb)
4761 if (bb->next_bb != EXIT_BLOCK_PTR)
4762 sbitmap_intersection_of_succs (hoist_vbeout[bb->index],
4763 hoist_vbein, bb->index);
4765 changed |= sbitmap_a_or_b_and_c_cg (hoist_vbein[bb->index],
4766 antloc[bb->index],
4767 hoist_vbeout[bb->index],
4768 transp[bb->index]);
4771 passes++;
4774 if (dump_file)
4775 fprintf (dump_file, "hoisting vbeinout computation: %d passes\n", passes);
4778 /* Top level routine to do the dataflow analysis needed by code hoisting. */
4780 static void
4781 compute_code_hoist_data (void)
4783 compute_local_properties (transp, comp, antloc, &expr_hash_table);
4784 compute_transpout ();
4785 compute_code_hoist_vbeinout ();
4786 calculate_dominance_info (CDI_DOMINATORS);
4787 if (dump_file)
4788 fprintf (dump_file, "\n");
4791 /* Determine if the expression identified by EXPR_INDEX would
4792 reach BB unimpared if it was placed at the end of EXPR_BB.
4794 It's unclear exactly what Muchnick meant by "unimpared". It seems
4795 to me that the expression must either be computed or transparent in
4796 *every* block in the path(s) from EXPR_BB to BB. Any other definition
4797 would allow the expression to be hoisted out of loops, even if
4798 the expression wasn't a loop invariant.
4800 Contrast this to reachability for PRE where an expression is
4801 considered reachable if *any* path reaches instead of *all*
4802 paths. */
4804 static int
4805 hoist_expr_reaches_here_p (basic_block expr_bb, int expr_index, basic_block bb, char *visited)
4807 edge pred;
4808 edge_iterator ei;
4809 int visited_allocated_locally = 0;
4812 if (visited == NULL)
4814 visited_allocated_locally = 1;
4815 visited = XCNEWVEC (char, last_basic_block);
4818 FOR_EACH_EDGE (pred, ei, bb->preds)
4820 basic_block pred_bb = pred->src;
4822 if (pred->src == ENTRY_BLOCK_PTR)
4823 break;
4824 else if (pred_bb == expr_bb)
4825 continue;
4826 else if (visited[pred_bb->index])
4827 continue;
4829 /* Does this predecessor generate this expression? */
4830 else if (TEST_BIT (comp[pred_bb->index], expr_index))
4831 break;
4832 else if (! TEST_BIT (transp[pred_bb->index], expr_index))
4833 break;
4835 /* Not killed. */
4836 else
4838 visited[pred_bb->index] = 1;
4839 if (! hoist_expr_reaches_here_p (expr_bb, expr_index,
4840 pred_bb, visited))
4841 break;
4844 if (visited_allocated_locally)
4845 free (visited);
4847 return (pred == NULL);
4850 /* Actually perform code hoisting. */
4852 static void
4853 hoist_code (void)
4855 basic_block bb, dominated;
4856 VEC (basic_block, heap) *domby;
4857 unsigned int i,j;
4858 struct expr **index_map;
4859 struct expr *expr;
4861 sbitmap_vector_zero (hoist_exprs, last_basic_block);
4863 /* Compute a mapping from expression number (`bitmap_index') to
4864 hash table entry. */
4866 index_map = XCNEWVEC (struct expr *, expr_hash_table.n_elems);
4867 for (i = 0; i < expr_hash_table.size; i++)
4868 for (expr = expr_hash_table.table[i]; expr != NULL; expr = expr->next_same_hash)
4869 index_map[expr->bitmap_index] = expr;
4871 /* Walk over each basic block looking for potentially hoistable
4872 expressions, nothing gets hoisted from the entry block. */
4873 FOR_EACH_BB (bb)
4875 int found = 0;
4876 int insn_inserted_p;
4878 domby = get_dominated_by (CDI_DOMINATORS, bb);
4879 /* Examine each expression that is very busy at the exit of this
4880 block. These are the potentially hoistable expressions. */
4881 for (i = 0; i < hoist_vbeout[bb->index]->n_bits; i++)
4883 int hoistable = 0;
4885 if (TEST_BIT (hoist_vbeout[bb->index], i)
4886 && TEST_BIT (transpout[bb->index], i))
4888 /* We've found a potentially hoistable expression, now
4889 we look at every block BB dominates to see if it
4890 computes the expression. */
4891 for (j = 0; VEC_iterate (basic_block, domby, j, dominated); j++)
4893 /* Ignore self dominance. */
4894 if (bb == dominated)
4895 continue;
4896 /* We've found a dominated block, now see if it computes
4897 the busy expression and whether or not moving that
4898 expression to the "beginning" of that block is safe. */
4899 if (!TEST_BIT (antloc[dominated->index], i))
4900 continue;
4902 /* Note if the expression would reach the dominated block
4903 unimpared if it was placed at the end of BB.
4905 Keep track of how many times this expression is hoistable
4906 from a dominated block into BB. */
4907 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
4908 hoistable++;
4911 /* If we found more than one hoistable occurrence of this
4912 expression, then note it in the bitmap of expressions to
4913 hoist. It makes no sense to hoist things which are computed
4914 in only one BB, and doing so tends to pessimize register
4915 allocation. One could increase this value to try harder
4916 to avoid any possible code expansion due to register
4917 allocation issues; however experiments have shown that
4918 the vast majority of hoistable expressions are only movable
4919 from two successors, so raising this threshold is likely
4920 to nullify any benefit we get from code hoisting. */
4921 if (hoistable > 1)
4923 SET_BIT (hoist_exprs[bb->index], i);
4924 found = 1;
4928 /* If we found nothing to hoist, then quit now. */
4929 if (! found)
4931 VEC_free (basic_block, heap, domby);
4932 continue;
4935 /* Loop over all the hoistable expressions. */
4936 for (i = 0; i < hoist_exprs[bb->index]->n_bits; i++)
4938 /* We want to insert the expression into BB only once, so
4939 note when we've inserted it. */
4940 insn_inserted_p = 0;
4942 /* These tests should be the same as the tests above. */
4943 if (TEST_BIT (hoist_exprs[bb->index], i))
4945 /* We've found a potentially hoistable expression, now
4946 we look at every block BB dominates to see if it
4947 computes the expression. */
4948 for (j = 0; VEC_iterate (basic_block, domby, j, dominated); j++)
4950 /* Ignore self dominance. */
4951 if (bb == dominated)
4952 continue;
4954 /* We've found a dominated block, now see if it computes
4955 the busy expression and whether or not moving that
4956 expression to the "beginning" of that block is safe. */
4957 if (!TEST_BIT (antloc[dominated->index], i))
4958 continue;
4960 /* The expression is computed in the dominated block and
4961 it would be safe to compute it at the start of the
4962 dominated block. Now we have to determine if the
4963 expression would reach the dominated block if it was
4964 placed at the end of BB. */
4965 if (hoist_expr_reaches_here_p (bb, i, dominated, NULL))
4967 struct expr *expr = index_map[i];
4968 struct occr *occr = expr->antic_occr;
4969 rtx insn;
4970 rtx set;
4972 /* Find the right occurrence of this expression. */
4973 while (BLOCK_FOR_INSN (occr->insn) != dominated && occr)
4974 occr = occr->next;
4976 gcc_assert (occr);
4977 insn = occr->insn;
4978 set = single_set (insn);
4979 gcc_assert (set);
4981 /* Create a pseudo-reg to store the result of reaching
4982 expressions into. Get the mode for the new pseudo
4983 from the mode of the original destination pseudo. */
4984 if (expr->reaching_reg == NULL)
4985 expr->reaching_reg
4986 = gen_reg_rtx (GET_MODE (SET_DEST (set)));
4988 gcse_emit_move_after (expr->reaching_reg, SET_DEST (set), insn);
4989 delete_insn (insn);
4990 occr->deleted_p = 1;
4991 if (!insn_inserted_p)
4993 insert_insn_end_basic_block (index_map[i], bb, 0);
4994 insn_inserted_p = 1;
5000 VEC_free (basic_block, heap, domby);
5003 free (index_map);
5006 /* Top level routine to perform one code hoisting (aka unification) pass
5008 Return nonzero if a change was made. */
5010 static int
5011 one_code_hoisting_pass (void)
5013 int changed = 0;
5015 alloc_hash_table (max_cuid, &expr_hash_table, 0);
5016 compute_hash_table (&expr_hash_table);
5017 if (dump_file)
5018 dump_hash_table (dump_file, "Code Hosting Expressions", &expr_hash_table);
5020 if (expr_hash_table.n_elems > 0)
5022 alloc_code_hoist_mem (last_basic_block, expr_hash_table.n_elems);
5023 compute_code_hoist_data ();
5024 hoist_code ();
5025 free_code_hoist_mem ();
5028 free_hash_table (&expr_hash_table);
5030 return changed;
5033 /* Here we provide the things required to do store motion towards
5034 the exit. In order for this to be effective, gcse also needed to
5035 be taught how to move a load when it is kill only by a store to itself.
5037 int i;
5038 float a[10];
5040 void foo(float scale)
5042 for (i=0; i<10; i++)
5043 a[i] *= scale;
5046 'i' is both loaded and stored to in the loop. Normally, gcse cannot move
5047 the load out since its live around the loop, and stored at the bottom
5048 of the loop.
5050 The 'Load Motion' referred to and implemented in this file is
5051 an enhancement to gcse which when using edge based lcm, recognizes
5052 this situation and allows gcse to move the load out of the loop.
5054 Once gcse has hoisted the load, store motion can then push this
5055 load towards the exit, and we end up with no loads or stores of 'i'
5056 in the loop. */
5058 static hashval_t
5059 pre_ldst_expr_hash (const void *p)
5061 int do_not_record_p = 0;
5062 const struct ls_expr *x = p;
5063 return hash_rtx (x->pattern, GET_MODE (x->pattern), &do_not_record_p, NULL, false);
5066 static int
5067 pre_ldst_expr_eq (const void *p1, const void *p2)
5069 const struct ls_expr *ptr1 = p1, *ptr2 = p2;
5070 return expr_equiv_p (ptr1->pattern, ptr2->pattern);
5073 /* This will search the ldst list for a matching expression. If it
5074 doesn't find one, we create one and initialize it. */
5076 static struct ls_expr *
5077 ldst_entry (rtx x)
5079 int do_not_record_p = 0;
5080 struct ls_expr * ptr;
5081 unsigned int hash;
5082 void **slot;
5083 struct ls_expr e;
5085 hash = hash_rtx (x, GET_MODE (x), &do_not_record_p,
5086 NULL, /*have_reg_qty=*/false);
5088 e.pattern = x;
5089 slot = htab_find_slot_with_hash (pre_ldst_table, &e, hash, INSERT);
5090 if (*slot)
5091 return (struct ls_expr *)*slot;
5093 ptr = XNEW (struct ls_expr);
5095 ptr->next = pre_ldst_mems;
5096 ptr->expr = NULL;
5097 ptr->pattern = x;
5098 ptr->pattern_regs = NULL_RTX;
5099 ptr->loads = NULL_RTX;
5100 ptr->stores = NULL_RTX;
5101 ptr->reaching_reg = NULL_RTX;
5102 ptr->invalid = 0;
5103 ptr->index = 0;
5104 ptr->hash_index = hash;
5105 pre_ldst_mems = ptr;
5106 *slot = ptr;
5108 return ptr;
5111 /* Free up an individual ldst entry. */
5113 static void
5114 free_ldst_entry (struct ls_expr * ptr)
5116 free_INSN_LIST_list (& ptr->loads);
5117 free_INSN_LIST_list (& ptr->stores);
5119 free (ptr);
5122 /* Free up all memory associated with the ldst list. */
5124 static void
5125 free_ldst_mems (void)
5127 if (pre_ldst_table)
5128 htab_delete (pre_ldst_table);
5129 pre_ldst_table = NULL;
5131 while (pre_ldst_mems)
5133 struct ls_expr * tmp = pre_ldst_mems;
5135 pre_ldst_mems = pre_ldst_mems->next;
5137 free_ldst_entry (tmp);
5140 pre_ldst_mems = NULL;
5143 /* Dump debugging info about the ldst list. */
5145 static void
5146 print_ldst_list (FILE * file)
5148 struct ls_expr * ptr;
5150 fprintf (file, "LDST list: \n");
5152 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
5154 fprintf (file, " Pattern (%3d): ", ptr->index);
5156 print_rtl (file, ptr->pattern);
5158 fprintf (file, "\n Loads : ");
5160 if (ptr->loads)
5161 print_rtl (file, ptr->loads);
5162 else
5163 fprintf (file, "(nil)");
5165 fprintf (file, "\n Stores : ");
5167 if (ptr->stores)
5168 print_rtl (file, ptr->stores);
5169 else
5170 fprintf (file, "(nil)");
5172 fprintf (file, "\n\n");
5175 fprintf (file, "\n");
5178 /* Returns 1 if X is in the list of ldst only expressions. */
5180 static struct ls_expr *
5181 find_rtx_in_ldst (rtx x)
5183 struct ls_expr e;
5184 void **slot;
5185 if (!pre_ldst_table)
5186 return NULL;
5187 e.pattern = x;
5188 slot = htab_find_slot (pre_ldst_table, &e, NO_INSERT);
5189 if (!slot || ((struct ls_expr *)*slot)->invalid)
5190 return NULL;
5191 return *slot;
5194 /* Assign each element of the list of mems a monotonically increasing value. */
5196 static int
5197 enumerate_ldsts (void)
5199 struct ls_expr * ptr;
5200 int n = 0;
5202 for (ptr = pre_ldst_mems; ptr != NULL; ptr = ptr->next)
5203 ptr->index = n++;
5205 return n;
5208 /* Return first item in the list. */
5210 static inline struct ls_expr *
5211 first_ls_expr (void)
5213 return pre_ldst_mems;
5216 /* Return the next item in the list after the specified one. */
5218 static inline struct ls_expr *
5219 next_ls_expr (struct ls_expr * ptr)
5221 return ptr->next;
5224 /* Load Motion for loads which only kill themselves. */
5226 /* Return true if x is a simple MEM operation, with no registers or
5227 side effects. These are the types of loads we consider for the
5228 ld_motion list, otherwise we let the usual aliasing take care of it. */
5230 static int
5231 simple_mem (const_rtx x)
5233 if (! MEM_P (x))
5234 return 0;
5236 if (MEM_VOLATILE_P (x))
5237 return 0;
5239 if (GET_MODE (x) == BLKmode)
5240 return 0;
5242 /* If we are handling exceptions, we must be careful with memory references
5243 that may trap. If we are not, the behavior is undefined, so we may just
5244 continue. */
5245 if (flag_non_call_exceptions && may_trap_p (x))
5246 return 0;
5248 if (side_effects_p (x))
5249 return 0;
5251 /* Do not consider function arguments passed on stack. */
5252 if (reg_mentioned_p (stack_pointer_rtx, x))
5253 return 0;
5255 if (flag_float_store && FLOAT_MODE_P (GET_MODE (x)))
5256 return 0;
5258 return 1;
5261 /* Make sure there isn't a buried reference in this pattern anywhere.
5262 If there is, invalidate the entry for it since we're not capable
5263 of fixing it up just yet.. We have to be sure we know about ALL
5264 loads since the aliasing code will allow all entries in the
5265 ld_motion list to not-alias itself. If we miss a load, we will get
5266 the wrong value since gcse might common it and we won't know to
5267 fix it up. */
5269 static void
5270 invalidate_any_buried_refs (rtx x)
5272 const char * fmt;
5273 int i, j;
5274 struct ls_expr * ptr;
5276 /* Invalidate it in the list. */
5277 if (MEM_P (x) && simple_mem (x))
5279 ptr = ldst_entry (x);
5280 ptr->invalid = 1;
5283 /* Recursively process the insn. */
5284 fmt = GET_RTX_FORMAT (GET_CODE (x));
5286 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0; i--)
5288 if (fmt[i] == 'e')
5289 invalidate_any_buried_refs (XEXP (x, i));
5290 else if (fmt[i] == 'E')
5291 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5292 invalidate_any_buried_refs (XVECEXP (x, i, j));
5296 /* Find all the 'simple' MEMs which are used in LOADs and STORES. Simple
5297 being defined as MEM loads and stores to symbols, with no side effects
5298 and no registers in the expression. For a MEM destination, we also
5299 check that the insn is still valid if we replace the destination with a
5300 REG, as is done in update_ld_motion_stores. If there are any uses/defs
5301 which don't match this criteria, they are invalidated and trimmed out
5302 later. */
5304 static void
5305 compute_ld_motion_mems (void)
5307 struct ls_expr * ptr;
5308 basic_block bb;
5309 rtx insn;
5311 pre_ldst_mems = NULL;
5312 pre_ldst_table = htab_create (13, pre_ldst_expr_hash,
5313 pre_ldst_expr_eq, NULL);
5315 FOR_EACH_BB (bb)
5317 FOR_BB_INSNS (bb, insn)
5319 if (INSN_P (insn))
5321 if (GET_CODE (PATTERN (insn)) == SET)
5323 rtx src = SET_SRC (PATTERN (insn));
5324 rtx dest = SET_DEST (PATTERN (insn));
5326 /* Check for a simple LOAD... */
5327 if (MEM_P (src) && simple_mem (src))
5329 ptr = ldst_entry (src);
5330 if (REG_P (dest))
5331 ptr->loads = alloc_INSN_LIST (insn, ptr->loads);
5332 else
5333 ptr->invalid = 1;
5335 else
5337 /* Make sure there isn't a buried load somewhere. */
5338 invalidate_any_buried_refs (src);
5341 /* Check for stores. Don't worry about aliased ones, they
5342 will block any movement we might do later. We only care
5343 about this exact pattern since those are the only
5344 circumstance that we will ignore the aliasing info. */
5345 if (MEM_P (dest) && simple_mem (dest))
5347 ptr = ldst_entry (dest);
5349 if (! MEM_P (src)
5350 && GET_CODE (src) != ASM_OPERANDS
5351 /* Check for REG manually since want_to_gcse_p
5352 returns 0 for all REGs. */
5353 && can_assign_to_reg_p (src))
5354 ptr->stores = alloc_INSN_LIST (insn, ptr->stores);
5355 else
5356 ptr->invalid = 1;
5359 else
5360 invalidate_any_buried_refs (PATTERN (insn));
5366 /* Remove any references that have been either invalidated or are not in the
5367 expression list for pre gcse. */
5369 static void
5370 trim_ld_motion_mems (void)
5372 struct ls_expr * * last = & pre_ldst_mems;
5373 struct ls_expr * ptr = pre_ldst_mems;
5375 while (ptr != NULL)
5377 struct expr * expr;
5379 /* Delete if entry has been made invalid. */
5380 if (! ptr->invalid)
5382 /* Delete if we cannot find this mem in the expression list. */
5383 unsigned int hash = ptr->hash_index % expr_hash_table.size;
5385 for (expr = expr_hash_table.table[hash];
5386 expr != NULL;
5387 expr = expr->next_same_hash)
5388 if (expr_equiv_p (expr->expr, ptr->pattern))
5389 break;
5391 else
5392 expr = (struct expr *) 0;
5394 if (expr)
5396 /* Set the expression field if we are keeping it. */
5397 ptr->expr = expr;
5398 last = & ptr->next;
5399 ptr = ptr->next;
5401 else
5403 *last = ptr->next;
5404 htab_remove_elt_with_hash (pre_ldst_table, ptr, ptr->hash_index);
5405 free_ldst_entry (ptr);
5406 ptr = * last;
5410 /* Show the world what we've found. */
5411 if (dump_file && pre_ldst_mems != NULL)
5412 print_ldst_list (dump_file);
5415 /* This routine will take an expression which we are replacing with
5416 a reaching register, and update any stores that are needed if
5417 that expression is in the ld_motion list. Stores are updated by
5418 copying their SRC to the reaching register, and then storing
5419 the reaching register into the store location. These keeps the
5420 correct value in the reaching register for the loads. */
5422 static void
5423 update_ld_motion_stores (struct expr * expr)
5425 struct ls_expr * mem_ptr;
5427 if ((mem_ptr = find_rtx_in_ldst (expr->expr)))
5429 /* We can try to find just the REACHED stores, but is shouldn't
5430 matter to set the reaching reg everywhere... some might be
5431 dead and should be eliminated later. */
5433 /* We replace (set mem expr) with (set reg expr) (set mem reg)
5434 where reg is the reaching reg used in the load. We checked in
5435 compute_ld_motion_mems that we can replace (set mem expr) with
5436 (set reg expr) in that insn. */
5437 rtx list = mem_ptr->stores;
5439 for ( ; list != NULL_RTX; list = XEXP (list, 1))
5441 rtx insn = XEXP (list, 0);
5442 rtx pat = PATTERN (insn);
5443 rtx src = SET_SRC (pat);
5444 rtx reg = expr->reaching_reg;
5445 rtx copy, new;
5447 /* If we've already copied it, continue. */
5448 if (expr->reaching_reg == src)
5449 continue;
5451 if (dump_file)
5453 fprintf (dump_file, "PRE: store updated with reaching reg ");
5454 print_rtl (dump_file, expr->reaching_reg);
5455 fprintf (dump_file, ":\n ");
5456 print_inline_rtx (dump_file, insn, 8);
5457 fprintf (dump_file, "\n");
5460 copy = gen_move_insn ( reg, copy_rtx (SET_SRC (pat)));
5461 new = emit_insn_before (copy, insn);
5462 record_one_set (REGNO (reg), new);
5463 SET_SRC (pat) = reg;
5464 df_insn_rescan (insn);
5466 /* un-recognize this pattern since it's probably different now. */
5467 INSN_CODE (insn) = -1;
5468 gcse_create_count++;
5473 /* Store motion code. */
5475 #define ANTIC_STORE_LIST(x) ((x)->loads)
5476 #define AVAIL_STORE_LIST(x) ((x)->stores)
5477 #define LAST_AVAIL_CHECK_FAILURE(x) ((x)->reaching_reg)
5479 /* This is used to communicate the target bitvector we want to use in the
5480 reg_set_info routine when called via the note_stores mechanism. */
5481 static int * regvec;
5483 /* And current insn, for the same routine. */
5484 static rtx compute_store_table_current_insn;
5486 /* Used in computing the reverse edge graph bit vectors. */
5487 static sbitmap * st_antloc;
5489 /* Global holding the number of store expressions we are dealing with. */
5490 static int num_stores;
5492 /* Checks to set if we need to mark a register set. Called from
5493 note_stores. */
5495 static void
5496 reg_set_info (rtx dest, const_rtx setter ATTRIBUTE_UNUSED,
5497 void *data)
5499 sbitmap bb_reg = data;
5501 if (GET_CODE (dest) == SUBREG)
5502 dest = SUBREG_REG (dest);
5504 if (REG_P (dest))
5506 regvec[REGNO (dest)] = INSN_UID (compute_store_table_current_insn);
5507 if (bb_reg)
5508 SET_BIT (bb_reg, REGNO (dest));
5512 /* Clear any mark that says that this insn sets dest. Called from
5513 note_stores. */
5515 static void
5516 reg_clear_last_set (rtx dest, const_rtx setter ATTRIBUTE_UNUSED,
5517 void *data)
5519 int *dead_vec = data;
5521 if (GET_CODE (dest) == SUBREG)
5522 dest = SUBREG_REG (dest);
5524 if (REG_P (dest) &&
5525 dead_vec[REGNO (dest)] == INSN_UID (compute_store_table_current_insn))
5526 dead_vec[REGNO (dest)] = 0;
5529 /* Return zero if some of the registers in list X are killed
5530 due to set of registers in bitmap REGS_SET. */
5532 static bool
5533 store_ops_ok (const_rtx x, int *regs_set)
5535 const_rtx reg;
5537 for (; x; x = XEXP (x, 1))
5539 reg = XEXP (x, 0);
5540 if (regs_set[REGNO(reg)])
5541 return false;
5544 return true;
5547 /* Returns a list of registers mentioned in X. */
5548 static rtx
5549 extract_mentioned_regs (rtx x)
5551 return extract_mentioned_regs_helper (x, NULL_RTX);
5554 /* Helper for extract_mentioned_regs; ACCUM is used to accumulate used
5555 registers. */
5556 static rtx
5557 extract_mentioned_regs_helper (rtx x, rtx accum)
5559 int i;
5560 enum rtx_code code;
5561 const char * fmt;
5563 /* Repeat is used to turn tail-recursion into iteration. */
5564 repeat:
5566 if (x == 0)
5567 return accum;
5569 code = GET_CODE (x);
5570 switch (code)
5572 case REG:
5573 return alloc_EXPR_LIST (0, x, accum);
5575 case MEM:
5576 x = XEXP (x, 0);
5577 goto repeat;
5579 case PRE_DEC:
5580 case PRE_INC:
5581 case PRE_MODIFY:
5582 case POST_DEC:
5583 case POST_INC:
5584 case POST_MODIFY:
5585 /* We do not run this function with arguments having side effects. */
5586 gcc_unreachable ();
5588 case PC:
5589 case CC0: /*FIXME*/
5590 case CONST:
5591 case CONST_INT:
5592 case CONST_DOUBLE:
5593 case CONST_FIXED:
5594 case CONST_VECTOR:
5595 case SYMBOL_REF:
5596 case LABEL_REF:
5597 case ADDR_VEC:
5598 case ADDR_DIFF_VEC:
5599 return accum;
5601 default:
5602 break;
5605 i = GET_RTX_LENGTH (code) - 1;
5606 fmt = GET_RTX_FORMAT (code);
5608 for (; i >= 0; i--)
5610 if (fmt[i] == 'e')
5612 rtx tem = XEXP (x, i);
5614 /* If we are about to do the last recursive call
5615 needed at this level, change it into iteration. */
5616 if (i == 0)
5618 x = tem;
5619 goto repeat;
5622 accum = extract_mentioned_regs_helper (tem, accum);
5624 else if (fmt[i] == 'E')
5626 int j;
5628 for (j = 0; j < XVECLEN (x, i); j++)
5629 accum = extract_mentioned_regs_helper (XVECEXP (x, i, j), accum);
5633 return accum;
5636 /* Determine whether INSN is MEM store pattern that we will consider moving.
5637 REGS_SET_BEFORE is bitmap of registers set before (and including) the
5638 current insn, REGS_SET_AFTER is bitmap of registers set after (and
5639 including) the insn in this basic block. We must be passing through BB from
5640 head to end, as we are using this fact to speed things up.
5642 The results are stored this way:
5644 -- the first anticipatable expression is added into ANTIC_STORE_LIST
5645 -- if the processed expression is not anticipatable, NULL_RTX is added
5646 there instead, so that we can use it as indicator that no further
5647 expression of this type may be anticipatable
5648 -- if the expression is available, it is added as head of AVAIL_STORE_LIST;
5649 consequently, all of them but this head are dead and may be deleted.
5650 -- if the expression is not available, the insn due to that it fails to be
5651 available is stored in reaching_reg.
5653 The things are complicated a bit by fact that there already may be stores
5654 to the same MEM from other blocks; also caller must take care of the
5655 necessary cleanup of the temporary markers after end of the basic block.
5658 static void
5659 find_moveable_store (rtx insn, int *regs_set_before, int *regs_set_after)
5661 struct ls_expr * ptr;
5662 rtx dest, set, tmp;
5663 int check_anticipatable, check_available;
5664 basic_block bb = BLOCK_FOR_INSN (insn);
5666 set = single_set (insn);
5667 if (!set)
5668 return;
5670 dest = SET_DEST (set);
5672 if (! MEM_P (dest) || MEM_VOLATILE_P (dest)
5673 || GET_MODE (dest) == BLKmode)
5674 return;
5676 if (side_effects_p (dest))
5677 return;
5679 /* If we are handling exceptions, we must be careful with memory references
5680 that may trap. If we are not, the behavior is undefined, so we may just
5681 continue. */
5682 if (flag_non_call_exceptions && may_trap_p (dest))
5683 return;
5685 /* Even if the destination cannot trap, the source may. In this case we'd
5686 need to handle updating the REG_EH_REGION note. */
5687 if (find_reg_note (insn, REG_EH_REGION, NULL_RTX))
5688 return;
5690 /* Make sure that the SET_SRC of this store insns can be assigned to
5691 a register, or we will fail later on in replace_store_insn, which
5692 assumes that we can do this. But sometimes the target machine has
5693 oddities like MEM read-modify-write instruction. See for example
5694 PR24257. */
5695 if (!can_assign_to_reg_p (SET_SRC (set)))
5696 return;
5698 ptr = ldst_entry (dest);
5699 if (!ptr->pattern_regs)
5700 ptr->pattern_regs = extract_mentioned_regs (dest);
5702 /* Do not check for anticipatability if we either found one anticipatable
5703 store already, or tested for one and found out that it was killed. */
5704 check_anticipatable = 0;
5705 if (!ANTIC_STORE_LIST (ptr))
5706 check_anticipatable = 1;
5707 else
5709 tmp = XEXP (ANTIC_STORE_LIST (ptr), 0);
5710 if (tmp != NULL_RTX
5711 && BLOCK_FOR_INSN (tmp) != bb)
5712 check_anticipatable = 1;
5714 if (check_anticipatable)
5716 if (store_killed_before (dest, ptr->pattern_regs, insn, bb, regs_set_before))
5717 tmp = NULL_RTX;
5718 else
5719 tmp = insn;
5720 ANTIC_STORE_LIST (ptr) = alloc_INSN_LIST (tmp,
5721 ANTIC_STORE_LIST (ptr));
5724 /* It is not necessary to check whether store is available if we did
5725 it successfully before; if we failed before, do not bother to check
5726 until we reach the insn that caused us to fail. */
5727 check_available = 0;
5728 if (!AVAIL_STORE_LIST (ptr))
5729 check_available = 1;
5730 else
5732 tmp = XEXP (AVAIL_STORE_LIST (ptr), 0);
5733 if (BLOCK_FOR_INSN (tmp) != bb)
5734 check_available = 1;
5736 if (check_available)
5738 /* Check that we have already reached the insn at that the check
5739 failed last time. */
5740 if (LAST_AVAIL_CHECK_FAILURE (ptr))
5742 for (tmp = BB_END (bb);
5743 tmp != insn && tmp != LAST_AVAIL_CHECK_FAILURE (ptr);
5744 tmp = PREV_INSN (tmp))
5745 continue;
5746 if (tmp == insn)
5747 check_available = 0;
5749 else
5750 check_available = store_killed_after (dest, ptr->pattern_regs, insn,
5751 bb, regs_set_after,
5752 &LAST_AVAIL_CHECK_FAILURE (ptr));
5754 if (!check_available)
5755 AVAIL_STORE_LIST (ptr) = alloc_INSN_LIST (insn, AVAIL_STORE_LIST (ptr));
5758 /* Find available and anticipatable stores. */
5760 static int
5761 compute_store_table (void)
5763 int ret;
5764 basic_block bb;
5765 unsigned regno;
5766 rtx insn, pat, tmp;
5767 int *last_set_in, *already_set;
5768 struct ls_expr * ptr, **prev_next_ptr_ptr;
5770 max_gcse_regno = max_reg_num ();
5772 reg_set_in_block = sbitmap_vector_alloc (last_basic_block,
5773 max_gcse_regno);
5774 sbitmap_vector_zero (reg_set_in_block, last_basic_block);
5775 pre_ldst_mems = 0;
5776 pre_ldst_table = htab_create (13, pre_ldst_expr_hash,
5777 pre_ldst_expr_eq, NULL);
5778 last_set_in = XCNEWVEC (int, max_gcse_regno);
5779 already_set = XNEWVEC (int, max_gcse_regno);
5781 /* Find all the stores we care about. */
5782 FOR_EACH_BB (bb)
5784 /* First compute the registers set in this block. */
5785 regvec = last_set_in;
5787 FOR_BB_INSNS (bb, insn)
5789 if (! INSN_P (insn))
5790 continue;
5792 if (CALL_P (insn))
5794 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
5795 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
5797 last_set_in[regno] = INSN_UID (insn);
5798 SET_BIT (reg_set_in_block[bb->index], regno);
5802 pat = PATTERN (insn);
5803 compute_store_table_current_insn = insn;
5804 note_stores (pat, reg_set_info, reg_set_in_block[bb->index]);
5807 /* Now find the stores. */
5808 memset (already_set, 0, sizeof (int) * max_gcse_regno);
5809 regvec = already_set;
5810 FOR_BB_INSNS (bb, insn)
5812 if (! INSN_P (insn))
5813 continue;
5815 if (CALL_P (insn))
5817 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
5818 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno))
5819 already_set[regno] = 1;
5822 pat = PATTERN (insn);
5823 note_stores (pat, reg_set_info, NULL);
5825 /* Now that we've marked regs, look for stores. */
5826 find_moveable_store (insn, already_set, last_set_in);
5828 /* Unmark regs that are no longer set. */
5829 compute_store_table_current_insn = insn;
5830 note_stores (pat, reg_clear_last_set, last_set_in);
5831 if (CALL_P (insn))
5833 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
5834 if (TEST_HARD_REG_BIT (regs_invalidated_by_call, regno)
5835 && last_set_in[regno] == INSN_UID (insn))
5836 last_set_in[regno] = 0;
5840 #ifdef ENABLE_CHECKING
5841 /* last_set_in should now be all-zero. */
5842 for (regno = 0; regno < max_gcse_regno; regno++)
5843 gcc_assert (!last_set_in[regno]);
5844 #endif
5846 /* Clear temporary marks. */
5847 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
5849 LAST_AVAIL_CHECK_FAILURE(ptr) = NULL_RTX;
5850 if (ANTIC_STORE_LIST (ptr)
5851 && (tmp = XEXP (ANTIC_STORE_LIST (ptr), 0)) == NULL_RTX)
5852 ANTIC_STORE_LIST (ptr) = XEXP (ANTIC_STORE_LIST (ptr), 1);
5856 /* Remove the stores that are not available anywhere, as there will
5857 be no opportunity to optimize them. */
5858 for (ptr = pre_ldst_mems, prev_next_ptr_ptr = &pre_ldst_mems;
5859 ptr != NULL;
5860 ptr = *prev_next_ptr_ptr)
5862 if (!AVAIL_STORE_LIST (ptr))
5864 *prev_next_ptr_ptr = ptr->next;
5865 htab_remove_elt_with_hash (pre_ldst_table, ptr, ptr->hash_index);
5866 free_ldst_entry (ptr);
5868 else
5869 prev_next_ptr_ptr = &ptr->next;
5872 ret = enumerate_ldsts ();
5874 if (dump_file)
5876 fprintf (dump_file, "ST_avail and ST_antic (shown under loads..)\n");
5877 print_ldst_list (dump_file);
5880 free (last_set_in);
5881 free (already_set);
5882 return ret;
5885 /* Check to see if the load X is aliased with STORE_PATTERN.
5886 AFTER is true if we are checking the case when STORE_PATTERN occurs
5887 after the X. */
5889 static bool
5890 load_kills_store (const_rtx x, const_rtx store_pattern, int after)
5892 if (after)
5893 return anti_dependence (x, store_pattern);
5894 else
5895 return true_dependence (store_pattern, GET_MODE (store_pattern), x,
5896 rtx_addr_varies_p);
5899 /* Go through the entire insn X, looking for any loads which might alias
5900 STORE_PATTERN. Return true if found.
5901 AFTER is true if we are checking the case when STORE_PATTERN occurs
5902 after the insn X. */
5904 static bool
5905 find_loads (const_rtx x, const_rtx store_pattern, int after)
5907 const char * fmt;
5908 int i, j;
5909 int ret = false;
5911 if (!x)
5912 return false;
5914 if (GET_CODE (x) == SET)
5915 x = SET_SRC (x);
5917 if (MEM_P (x))
5919 if (load_kills_store (x, store_pattern, after))
5920 return true;
5923 /* Recursively process the insn. */
5924 fmt = GET_RTX_FORMAT (GET_CODE (x));
5926 for (i = GET_RTX_LENGTH (GET_CODE (x)) - 1; i >= 0 && !ret; i--)
5928 if (fmt[i] == 'e')
5929 ret |= find_loads (XEXP (x, i), store_pattern, after);
5930 else if (fmt[i] == 'E')
5931 for (j = XVECLEN (x, i) - 1; j >= 0; j--)
5932 ret |= find_loads (XVECEXP (x, i, j), store_pattern, after);
5934 return ret;
5937 static inline bool
5938 store_killed_in_pat (const_rtx x, const_rtx pat, int after)
5940 if (GET_CODE (pat) == SET)
5942 rtx dest = SET_DEST (pat);
5944 if (GET_CODE (dest) == ZERO_EXTRACT)
5945 dest = XEXP (dest, 0);
5947 /* Check for memory stores to aliased objects. */
5948 if (MEM_P (dest)
5949 && !expr_equiv_p (dest, x))
5951 if (after)
5953 if (output_dependence (dest, x))
5954 return true;
5956 else
5958 if (output_dependence (x, dest))
5959 return true;
5964 if (find_loads (pat, x, after))
5965 return true;
5967 return false;
5970 /* Check if INSN kills the store pattern X (is aliased with it).
5971 AFTER is true if we are checking the case when store X occurs
5972 after the insn. Return true if it does. */
5974 static bool
5975 store_killed_in_insn (const_rtx x, const_rtx x_regs, const_rtx insn, int after)
5977 const_rtx reg, base, note, pat;
5979 if (!INSN_P (insn))
5980 return false;
5982 if (CALL_P (insn))
5984 /* A normal or pure call might read from pattern,
5985 but a const call will not. */
5986 if (! CONST_OR_PURE_CALL_P (insn) || pure_call_p (insn))
5987 return true;
5989 /* But even a const call reads its parameters. Check whether the
5990 base of some of registers used in mem is stack pointer. */
5991 for (reg = x_regs; reg; reg = XEXP (reg, 1))
5993 base = find_base_term (XEXP (reg, 0));
5994 if (!base
5995 || (GET_CODE (base) == ADDRESS
5996 && GET_MODE (base) == Pmode
5997 && XEXP (base, 0) == stack_pointer_rtx))
5998 return true;
6001 return false;
6004 pat = PATTERN (insn);
6005 if (GET_CODE (pat) == SET)
6007 if (store_killed_in_pat (x, pat, after))
6008 return true;
6010 else if (GET_CODE (pat) == PARALLEL)
6012 int i;
6014 for (i = 0; i < XVECLEN (pat, 0); i++)
6015 if (store_killed_in_pat (x, XVECEXP (pat, 0, i), after))
6016 return true;
6018 else if (find_loads (PATTERN (insn), x, after))
6019 return true;
6021 /* If this insn has a REG_EQUAL or REG_EQUIV note referencing a memory
6022 location aliased with X, then this insn kills X. */
6023 note = find_reg_equal_equiv_note (insn);
6024 if (! note)
6025 return false;
6026 note = XEXP (note, 0);
6028 /* However, if the note represents a must alias rather than a may
6029 alias relationship, then it does not kill X. */
6030 if (expr_equiv_p (note, x))
6031 return false;
6033 /* See if there are any aliased loads in the note. */
6034 return find_loads (note, x, after);
6037 /* Returns true if the expression X is loaded or clobbered on or after INSN
6038 within basic block BB. REGS_SET_AFTER is bitmap of registers set in
6039 or after the insn. X_REGS is list of registers mentioned in X. If the store
6040 is killed, return the last insn in that it occurs in FAIL_INSN. */
6042 static bool
6043 store_killed_after (const_rtx x, const_rtx x_regs, const_rtx insn, const_basic_block bb,
6044 int *regs_set_after, rtx *fail_insn)
6046 rtx last = BB_END (bb), act;
6048 if (!store_ops_ok (x_regs, regs_set_after))
6050 /* We do not know where it will happen. */
6051 if (fail_insn)
6052 *fail_insn = NULL_RTX;
6053 return true;
6056 /* Scan from the end, so that fail_insn is determined correctly. */
6057 for (act = last; act != PREV_INSN (insn); act = PREV_INSN (act))
6058 if (store_killed_in_insn (x, x_regs, act, false))
6060 if (fail_insn)
6061 *fail_insn = act;
6062 return true;
6065 return false;
6068 /* Returns true if the expression X is loaded or clobbered on or before INSN
6069 within basic block BB. X_REGS is list of registers mentioned in X.
6070 REGS_SET_BEFORE is bitmap of registers set before or in this insn. */
6071 static bool
6072 store_killed_before (const_rtx x, const_rtx x_regs, const_rtx insn, const_basic_block bb,
6073 int *regs_set_before)
6075 rtx first = BB_HEAD (bb);
6077 if (!store_ops_ok (x_regs, regs_set_before))
6078 return true;
6080 for ( ; insn != PREV_INSN (first); insn = PREV_INSN (insn))
6081 if (store_killed_in_insn (x, x_regs, insn, true))
6082 return true;
6084 return false;
6087 /* Fill in available, anticipatable, transparent and kill vectors in
6088 STORE_DATA, based on lists of available and anticipatable stores. */
6089 static void
6090 build_store_vectors (void)
6092 basic_block bb;
6093 int *regs_set_in_block;
6094 rtx insn, st;
6095 struct ls_expr * ptr;
6096 unsigned regno;
6098 /* Build the gen_vector. This is any store in the table which is not killed
6099 by aliasing later in its block. */
6100 ae_gen = sbitmap_vector_alloc (last_basic_block, num_stores);
6101 sbitmap_vector_zero (ae_gen, last_basic_block);
6103 st_antloc = sbitmap_vector_alloc (last_basic_block, num_stores);
6104 sbitmap_vector_zero (st_antloc, last_basic_block);
6106 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6108 for (st = AVAIL_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
6110 insn = XEXP (st, 0);
6111 bb = BLOCK_FOR_INSN (insn);
6113 /* If we've already seen an available expression in this block,
6114 we can delete this one (It occurs earlier in the block). We'll
6115 copy the SRC expression to an unused register in case there
6116 are any side effects. */
6117 if (TEST_BIT (ae_gen[bb->index], ptr->index))
6119 rtx r = gen_reg_rtx (GET_MODE (ptr->pattern));
6120 if (dump_file)
6121 fprintf (dump_file, "Removing redundant store:\n");
6122 replace_store_insn (r, XEXP (st, 0), bb, ptr);
6123 continue;
6125 SET_BIT (ae_gen[bb->index], ptr->index);
6128 for (st = ANTIC_STORE_LIST (ptr); st != NULL; st = XEXP (st, 1))
6130 insn = XEXP (st, 0);
6131 bb = BLOCK_FOR_INSN (insn);
6132 SET_BIT (st_antloc[bb->index], ptr->index);
6136 ae_kill = sbitmap_vector_alloc (last_basic_block, num_stores);
6137 sbitmap_vector_zero (ae_kill, last_basic_block);
6139 transp = sbitmap_vector_alloc (last_basic_block, num_stores);
6140 sbitmap_vector_zero (transp, last_basic_block);
6141 regs_set_in_block = XNEWVEC (int, max_gcse_regno);
6143 FOR_EACH_BB (bb)
6145 for (regno = 0; regno < max_gcse_regno; regno++)
6146 regs_set_in_block[regno] = TEST_BIT (reg_set_in_block[bb->index], regno);
6148 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6150 if (store_killed_after (ptr->pattern, ptr->pattern_regs, BB_HEAD (bb),
6151 bb, regs_set_in_block, NULL))
6153 /* It should not be necessary to consider the expression
6154 killed if it is both anticipatable and available. */
6155 if (!TEST_BIT (st_antloc[bb->index], ptr->index)
6156 || !TEST_BIT (ae_gen[bb->index], ptr->index))
6157 SET_BIT (ae_kill[bb->index], ptr->index);
6159 else
6160 SET_BIT (transp[bb->index], ptr->index);
6164 free (regs_set_in_block);
6166 if (dump_file)
6168 dump_sbitmap_vector (dump_file, "st_antloc", "", st_antloc, last_basic_block);
6169 dump_sbitmap_vector (dump_file, "st_kill", "", ae_kill, last_basic_block);
6170 dump_sbitmap_vector (dump_file, "Transpt", "", transp, last_basic_block);
6171 dump_sbitmap_vector (dump_file, "st_avloc", "", ae_gen, last_basic_block);
6175 /* Insert an instruction at the beginning of a basic block, and update
6176 the BB_HEAD if needed. */
6178 static void
6179 insert_insn_start_basic_block (rtx insn, basic_block bb)
6181 /* Insert at start of successor block. */
6182 rtx prev = PREV_INSN (BB_HEAD (bb));
6183 rtx before = BB_HEAD (bb);
6184 while (before != 0)
6186 if (! LABEL_P (before)
6187 && !NOTE_INSN_BASIC_BLOCK_P (before))
6188 break;
6189 prev = before;
6190 if (prev == BB_END (bb))
6191 break;
6192 before = NEXT_INSN (before);
6195 insn = emit_insn_after_noloc (insn, prev, bb);
6197 if (dump_file)
6199 fprintf (dump_file, "STORE_MOTION insert store at start of BB %d:\n",
6200 bb->index);
6201 print_inline_rtx (dump_file, insn, 6);
6202 fprintf (dump_file, "\n");
6206 /* This routine will insert a store on an edge. EXPR is the ldst entry for
6207 the memory reference, and E is the edge to insert it on. Returns nonzero
6208 if an edge insertion was performed. */
6210 static int
6211 insert_store (struct ls_expr * expr, edge e)
6213 rtx reg, insn;
6214 basic_block bb;
6215 edge tmp;
6216 edge_iterator ei;
6218 /* We did all the deleted before this insert, so if we didn't delete a
6219 store, then we haven't set the reaching reg yet either. */
6220 if (expr->reaching_reg == NULL_RTX)
6221 return 0;
6223 if (e->flags & EDGE_FAKE)
6224 return 0;
6226 reg = expr->reaching_reg;
6227 insn = gen_move_insn (copy_rtx (expr->pattern), reg);
6229 /* If we are inserting this expression on ALL predecessor edges of a BB,
6230 insert it at the start of the BB, and reset the insert bits on the other
6231 edges so we don't try to insert it on the other edges. */
6232 bb = e->dest;
6233 FOR_EACH_EDGE (tmp, ei, e->dest->preds)
6234 if (!(tmp->flags & EDGE_FAKE))
6236 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
6238 gcc_assert (index != EDGE_INDEX_NO_EDGE);
6239 if (! TEST_BIT (pre_insert_map[index], expr->index))
6240 break;
6243 /* If tmp is NULL, we found an insertion on every edge, blank the
6244 insertion vector for these edges, and insert at the start of the BB. */
6245 if (!tmp && bb != EXIT_BLOCK_PTR)
6247 FOR_EACH_EDGE (tmp, ei, e->dest->preds)
6249 int index = EDGE_INDEX (edge_list, tmp->src, tmp->dest);
6250 RESET_BIT (pre_insert_map[index], expr->index);
6252 insert_insn_start_basic_block (insn, bb);
6253 return 0;
6256 /* We can't put stores in the front of blocks pointed to by abnormal
6257 edges since that may put a store where one didn't used to be. */
6258 gcc_assert (!(e->flags & EDGE_ABNORMAL));
6260 insert_insn_on_edge (insn, e);
6262 if (dump_file)
6264 fprintf (dump_file, "STORE_MOTION insert insn on edge (%d, %d):\n",
6265 e->src->index, e->dest->index);
6266 print_inline_rtx (dump_file, insn, 6);
6267 fprintf (dump_file, "\n");
6270 return 1;
6273 /* Remove any REG_EQUAL or REG_EQUIV notes containing a reference to the
6274 memory location in SMEXPR set in basic block BB.
6276 This could be rather expensive. */
6278 static void
6279 remove_reachable_equiv_notes (basic_block bb, struct ls_expr *smexpr)
6281 edge_iterator *stack, ei;
6282 int sp;
6283 edge act;
6284 sbitmap visited = sbitmap_alloc (last_basic_block);
6285 rtx last, insn, note;
6286 rtx mem = smexpr->pattern;
6288 stack = XNEWVEC (edge_iterator, n_basic_blocks);
6289 sp = 0;
6290 ei = ei_start (bb->succs);
6292 sbitmap_zero (visited);
6294 act = (EDGE_COUNT (ei_container (ei)) > 0 ? EDGE_I (ei_container (ei), 0) : NULL);
6295 while (1)
6297 if (!act)
6299 if (!sp)
6301 free (stack);
6302 sbitmap_free (visited);
6303 return;
6305 act = ei_edge (stack[--sp]);
6307 bb = act->dest;
6309 if (bb == EXIT_BLOCK_PTR
6310 || TEST_BIT (visited, bb->index))
6312 if (!ei_end_p (ei))
6313 ei_next (&ei);
6314 act = (! ei_end_p (ei)) ? ei_edge (ei) : NULL;
6315 continue;
6317 SET_BIT (visited, bb->index);
6319 if (TEST_BIT (st_antloc[bb->index], smexpr->index))
6321 for (last = ANTIC_STORE_LIST (smexpr);
6322 BLOCK_FOR_INSN (XEXP (last, 0)) != bb;
6323 last = XEXP (last, 1))
6324 continue;
6325 last = XEXP (last, 0);
6327 else
6328 last = NEXT_INSN (BB_END (bb));
6330 for (insn = BB_HEAD (bb); insn != last; insn = NEXT_INSN (insn))
6331 if (INSN_P (insn))
6333 note = find_reg_equal_equiv_note (insn);
6334 if (!note || !expr_equiv_p (XEXP (note, 0), mem))
6335 continue;
6337 if (dump_file)
6338 fprintf (dump_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6339 INSN_UID (insn));
6340 remove_note (insn, note);
6343 if (!ei_end_p (ei))
6344 ei_next (&ei);
6345 act = (! ei_end_p (ei)) ? ei_edge (ei) : NULL;
6347 if (EDGE_COUNT (bb->succs) > 0)
6349 if (act)
6350 stack[sp++] = ei;
6351 ei = ei_start (bb->succs);
6352 act = (EDGE_COUNT (ei_container (ei)) > 0 ? EDGE_I (ei_container (ei), 0) : NULL);
6357 /* This routine will replace a store with a SET to a specified register. */
6359 static void
6360 replace_store_insn (rtx reg, rtx del, basic_block bb, struct ls_expr *smexpr)
6362 rtx insn, mem, note, set, ptr, pair;
6364 mem = smexpr->pattern;
6365 insn = gen_move_insn (reg, SET_SRC (single_set (del)));
6367 for (ptr = ANTIC_STORE_LIST (smexpr); ptr; ptr = XEXP (ptr, 1))
6368 if (XEXP (ptr, 0) == del)
6370 XEXP (ptr, 0) = insn;
6371 break;
6374 /* Move the notes from the deleted insn to its replacement, and patch
6375 up the LIBCALL notes. */
6376 REG_NOTES (insn) = REG_NOTES (del);
6378 note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
6379 if (note)
6381 pair = XEXP (note, 0);
6382 note = find_reg_note (pair, REG_LIBCALL, NULL_RTX);
6383 XEXP (note, 0) = insn;
6385 note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
6386 if (note)
6388 pair = XEXP (note, 0);
6389 note = find_reg_note (pair, REG_RETVAL, NULL_RTX);
6390 XEXP (note, 0) = insn;
6393 /* Emit the insn AFTER all the notes are transferred.
6394 This is cheaper since we avoid df rescanning for the note change. */
6395 insn = emit_insn_after (insn, del);
6397 if (dump_file)
6399 fprintf (dump_file,
6400 "STORE_MOTION delete insn in BB %d:\n ", bb->index);
6401 print_inline_rtx (dump_file, del, 6);
6402 fprintf (dump_file, "\nSTORE MOTION replaced with insn:\n ");
6403 print_inline_rtx (dump_file, insn, 6);
6404 fprintf (dump_file, "\n");
6407 delete_insn (del);
6409 /* Now we must handle REG_EQUAL notes whose contents is equal to the mem;
6410 they are no longer accurate provided that they are reached by this
6411 definition, so drop them. */
6412 for (; insn != NEXT_INSN (BB_END (bb)); insn = NEXT_INSN (insn))
6413 if (INSN_P (insn))
6415 set = single_set (insn);
6416 if (!set)
6417 continue;
6418 if (expr_equiv_p (SET_DEST (set), mem))
6419 return;
6420 note = find_reg_equal_equiv_note (insn);
6421 if (!note || !expr_equiv_p (XEXP (note, 0), mem))
6422 continue;
6424 if (dump_file)
6425 fprintf (dump_file, "STORE_MOTION drop REG_EQUAL note at insn %d:\n",
6426 INSN_UID (insn));
6427 remove_note (insn, note);
6429 remove_reachable_equiv_notes (bb, smexpr);
6433 /* Delete a store, but copy the value that would have been stored into
6434 the reaching_reg for later storing. */
6436 static void
6437 delete_store (struct ls_expr * expr, basic_block bb)
6439 rtx reg, i, del;
6441 if (expr->reaching_reg == NULL_RTX)
6442 expr->reaching_reg = gen_reg_rtx (GET_MODE (expr->pattern));
6444 reg = expr->reaching_reg;
6446 for (i = AVAIL_STORE_LIST (expr); i; i = XEXP (i, 1))
6448 del = XEXP (i, 0);
6449 if (BLOCK_FOR_INSN (del) == bb)
6451 /* We know there is only one since we deleted redundant
6452 ones during the available computation. */
6453 replace_store_insn (reg, del, bb, expr);
6454 break;
6459 /* Free memory used by store motion. */
6461 static void
6462 free_store_memory (void)
6464 free_ldst_mems ();
6466 if (ae_gen)
6467 sbitmap_vector_free (ae_gen);
6468 if (ae_kill)
6469 sbitmap_vector_free (ae_kill);
6470 if (transp)
6471 sbitmap_vector_free (transp);
6472 if (st_antloc)
6473 sbitmap_vector_free (st_antloc);
6474 if (pre_insert_map)
6475 sbitmap_vector_free (pre_insert_map);
6476 if (pre_delete_map)
6477 sbitmap_vector_free (pre_delete_map);
6478 if (reg_set_in_block)
6479 sbitmap_vector_free (reg_set_in_block);
6481 ae_gen = ae_kill = transp = st_antloc = NULL;
6482 pre_insert_map = pre_delete_map = reg_set_in_block = NULL;
6485 /* Perform store motion. Much like gcse, except we move expressions the
6486 other way by looking at the flowgraph in reverse. */
6488 static void
6489 store_motion (void)
6491 basic_block bb;
6492 int x;
6493 struct ls_expr * ptr;
6494 int update_flow = 0;
6496 if (dump_file)
6498 fprintf (dump_file, "before store motion\n");
6499 print_rtl (dump_file, get_insns ());
6502 init_alias_analysis ();
6504 /* Find all the available and anticipatable stores. */
6505 num_stores = compute_store_table ();
6506 if (num_stores == 0)
6508 htab_delete (pre_ldst_table);
6509 pre_ldst_table = NULL;
6510 sbitmap_vector_free (reg_set_in_block);
6511 end_alias_analysis ();
6512 return;
6515 /* Now compute kill & transp vectors. */
6516 build_store_vectors ();
6517 add_noreturn_fake_exit_edges ();
6518 connect_infinite_loops_to_exit ();
6520 edge_list = pre_edge_rev_lcm (num_stores, transp, ae_gen,
6521 st_antloc, ae_kill, &pre_insert_map,
6522 &pre_delete_map);
6524 /* Now we want to insert the new stores which are going to be needed. */
6525 for (ptr = first_ls_expr (); ptr != NULL; ptr = next_ls_expr (ptr))
6527 /* If any of the edges we have above are abnormal, we can't move this
6528 store. */
6529 for (x = NUM_EDGES (edge_list) - 1; x >= 0; x--)
6530 if (TEST_BIT (pre_insert_map[x], ptr->index)
6531 && (INDEX_EDGE (edge_list, x)->flags & EDGE_ABNORMAL))
6532 break;
6534 if (x >= 0)
6536 if (dump_file != NULL)
6537 fprintf (dump_file,
6538 "Can't replace store %d: abnormal edge from %d to %d\n",
6539 ptr->index, INDEX_EDGE (edge_list, x)->src->index,
6540 INDEX_EDGE (edge_list, x)->dest->index);
6541 continue;
6544 /* Now we want to insert the new stores which are going to be needed. */
6546 FOR_EACH_BB (bb)
6547 if (TEST_BIT (pre_delete_map[bb->index], ptr->index))
6548 delete_store (ptr, bb);
6550 for (x = 0; x < NUM_EDGES (edge_list); x++)
6551 if (TEST_BIT (pre_insert_map[x], ptr->index))
6552 update_flow |= insert_store (ptr, INDEX_EDGE (edge_list, x));
6555 if (update_flow)
6556 commit_edge_insertions ();
6558 free_store_memory ();
6559 free_edge_list (edge_list);
6560 remove_fake_exit_edges ();
6561 end_alias_analysis ();
6565 /* Entry point for jump bypassing optimization pass. */
6567 static int
6568 bypass_jumps (void)
6570 int changed;
6572 /* We do not construct an accurate cfg in functions which call
6573 setjmp, so just punt to be safe. */
6574 if (current_function_calls_setjmp)
6575 return 0;
6577 /* Identify the basic block information for this function, including
6578 successors and predecessors. */
6579 max_gcse_regno = max_reg_num ();
6581 if (dump_file)
6582 dump_flow_info (dump_file, dump_flags);
6584 /* Return if there's nothing to do, or it is too expensive. */
6585 if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1
6586 || is_too_expensive (_ ("jump bypassing disabled")))
6587 return 0;
6589 gcc_obstack_init (&gcse_obstack);
6590 bytes_used = 0;
6592 /* We need alias. */
6593 init_alias_analysis ();
6595 /* Record where pseudo-registers are set. This data is kept accurate
6596 during each pass. ??? We could also record hard-reg information here
6597 [since it's unchanging], however it is currently done during hash table
6598 computation.
6600 It may be tempting to compute MEM set information here too, but MEM sets
6601 will be subject to code motion one day and thus we need to compute
6602 information about memory sets when we build the hash tables. */
6604 alloc_reg_set_mem (max_gcse_regno);
6605 compute_sets ();
6607 max_gcse_regno = max_reg_num ();
6608 alloc_gcse_mem ();
6609 changed = one_cprop_pass (MAX_GCSE_PASSES + 2, true, true);
6610 free_gcse_mem ();
6612 if (dump_file)
6614 fprintf (dump_file, "BYPASS of %s: %d basic blocks, ",
6615 current_function_name (), n_basic_blocks);
6616 fprintf (dump_file, "%d bytes\n\n", bytes_used);
6619 obstack_free (&gcse_obstack, NULL);
6620 free_reg_set_mem ();
6622 /* We are finished with alias. */
6623 end_alias_analysis ();
6625 return changed;
6628 /* Return true if the graph is too expensive to optimize. PASS is the
6629 optimization about to be performed. */
6631 static bool
6632 is_too_expensive (const char *pass)
6634 /* Trying to perform global optimizations on flow graphs which have
6635 a high connectivity will take a long time and is unlikely to be
6636 particularly useful.
6638 In normal circumstances a cfg should have about twice as many
6639 edges as blocks. But we do not want to punish small functions
6640 which have a couple switch statements. Rather than simply
6641 threshold the number of blocks, uses something with a more
6642 graceful degradation. */
6643 if (n_edges > 20000 + n_basic_blocks * 4)
6645 warning (OPT_Wdisabled_optimization,
6646 "%s: %d basic blocks and %d edges/basic block",
6647 pass, n_basic_blocks, n_edges / n_basic_blocks);
6649 return true;
6652 /* If allocating memory for the cprop bitmap would take up too much
6653 storage it's better just to disable the optimization. */
6654 if ((n_basic_blocks
6655 * SBITMAP_SET_SIZE (max_reg_num ())
6656 * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
6658 warning (OPT_Wdisabled_optimization,
6659 "%s: %d basic blocks and %d registers",
6660 pass, n_basic_blocks, max_reg_num ());
6662 return true;
6665 return false;
6668 static bool
6669 gate_handle_jump_bypass (void)
6671 return optimize > 0 && flag_gcse;
6674 /* Perform jump bypassing and control flow optimizations. */
6675 static unsigned int
6676 rest_of_handle_jump_bypass (void)
6678 delete_unreachable_blocks ();
6679 if (bypass_jumps ())
6681 delete_trivially_dead_insns (get_insns (), max_reg_num ());
6682 rebuild_jump_labels (get_insns ());
6683 cleanup_cfg (0);
6685 return 0;
6688 struct tree_opt_pass pass_jump_bypass =
6690 "bypass", /* name */
6691 gate_handle_jump_bypass, /* gate */
6692 rest_of_handle_jump_bypass, /* execute */
6693 NULL, /* sub */
6694 NULL, /* next */
6695 0, /* static_pass_number */
6696 TV_BYPASS, /* tv_id */
6697 0, /* properties_required */
6698 0, /* properties_provided */
6699 0, /* properties_destroyed */
6700 0, /* todo_flags_start */
6701 TODO_dump_func |
6702 TODO_ggc_collect | TODO_verify_flow, /* todo_flags_finish */
6703 'G' /* letter */
6707 static bool
6708 gate_handle_gcse (void)
6710 return optimize > 0 && flag_gcse;
6714 static unsigned int
6715 rest_of_handle_gcse (void)
6717 int save_csb, save_cfj;
6718 int tem2 = 0, tem;
6719 tem = gcse_main (get_insns ());
6720 delete_trivially_dead_insns (get_insns (), max_reg_num ());
6721 rebuild_jump_labels (get_insns ());
6722 save_csb = flag_cse_skip_blocks;
6723 save_cfj = flag_cse_follow_jumps;
6724 flag_cse_skip_blocks = flag_cse_follow_jumps = 0;
6726 /* If -fexpensive-optimizations, re-run CSE to clean up things done
6727 by gcse. */
6728 if (flag_expensive_optimizations)
6730 timevar_push (TV_CSE);
6731 tem2 = cse_main (get_insns (), max_reg_num ());
6732 df_finish_pass (false);
6733 purge_all_dead_edges ();
6734 delete_trivially_dead_insns (get_insns (), max_reg_num ());
6735 timevar_pop (TV_CSE);
6736 cse_not_expected = !flag_rerun_cse_after_loop;
6739 /* If gcse or cse altered any jumps, rerun jump optimizations to clean
6740 things up. */
6741 if (tem || tem2 == 2)
6743 timevar_push (TV_JUMP);
6744 rebuild_jump_labels (get_insns ());
6745 cleanup_cfg (0);
6746 timevar_pop (TV_JUMP);
6748 else if (tem2 == 1)
6749 cleanup_cfg (0);
6751 flag_cse_skip_blocks = save_csb;
6752 flag_cse_follow_jumps = save_cfj;
6753 return 0;
6756 struct tree_opt_pass pass_gcse =
6758 "gcse1", /* name */
6759 gate_handle_gcse, /* gate */
6760 rest_of_handle_gcse, /* execute */
6761 NULL, /* sub */
6762 NULL, /* next */
6763 0, /* static_pass_number */
6764 TV_GCSE, /* tv_id */
6765 0, /* properties_required */
6766 0, /* properties_provided */
6767 0, /* properties_destroyed */
6768 0, /* todo_flags_start */
6769 TODO_df_finish | TODO_verify_rtl_sharing |
6770 TODO_dump_func |
6771 TODO_verify_flow | TODO_ggc_collect, /* todo_flags_finish */
6772 'G' /* letter */
6776 #include "gt-gcse.h"