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78d140c9 | 1 | /* Post reload partially redundant load elimination |
711789cc | 2 | Copyright (C) 2004-2013 Free Software Foundation, Inc. |
78d140c9 | 3 | |
4 | This file is part of GCC. | |
5 | ||
6 | GCC is free software; you can redistribute it and/or modify it under | |
7 | the terms of the GNU General Public License as published by the Free | |
8c4c00c1 | 8 | Software Foundation; either version 3, or (at your option) any later |
78d140c9 | 9 | version. |
10 | ||
11 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 | for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
8c4c00c1 | 17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
78d140c9 | 19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
23 | #include "tm.h" | |
0b205f4c | 24 | #include "diagnostic-core.h" |
78d140c9 | 25 | |
d9dd21a8 | 26 | #include "hash-table.h" |
78d140c9 | 27 | #include "rtl.h" |
28 | #include "tree.h" | |
29 | #include "tm_p.h" | |
30 | #include "regs.h" | |
31 | #include "hard-reg-set.h" | |
32 | #include "flags.h" | |
78d140c9 | 33 | #include "insn-config.h" |
34 | #include "recog.h" | |
35 | #include "basic-block.h" | |
78d140c9 | 36 | #include "function.h" |
37 | #include "expr.h" | |
38 | #include "except.h" | |
39 | #include "intl.h" | |
40 | #include "obstack.h" | |
41 | #include "hashtab.h" | |
42 | #include "params.h" | |
5ee7391d | 43 | #include "target.h" |
77fce4cd | 44 | #include "tree-pass.h" |
3072d30e | 45 | #include "dbgcnt.h" |
78d140c9 | 46 | |
47 | /* The following code implements gcse after reload, the purpose of this | |
48 | pass is to cleanup redundant loads generated by reload and other | |
49 | optimizations that come after gcse. It searches for simple inter-block | |
50 | redundancies and tries to eliminate them by adding moves and loads | |
51 | in cold places. | |
52 | ||
53 | Perform partially redundant load elimination, try to eliminate redundant | |
54 | loads created by the reload pass. We try to look for full or partial | |
55 | redundant loads fed by one or more loads/stores in predecessor BBs, | |
56 | and try adding loads to make them fully redundant. We also check if | |
57 | it's worth adding loads to be able to delete the redundant load. | |
58 | ||
59 | Algorithm: | |
60 | 1. Build available expressions hash table: | |
61 | For each load/store instruction, if the loaded/stored memory didn't | |
62 | change until the end of the basic block add this memory expression to | |
63 | the hash table. | |
64 | 2. Perform Redundancy elimination: | |
65 | For each load instruction do the following: | |
66 | perform partial redundancy elimination, check if it's worth adding | |
67 | loads to make the load fully redundant. If so add loads and | |
68 | register copies and delete the load. | |
69 | 3. Delete instructions made redundant in step 2. | |
70 | ||
71 | Future enhancement: | |
72 | If the loaded register is used/defined between load and some store, | |
73 | look for some other free register between load and all its stores, | |
74 | and replace the load with a copy from this register to the loaded | |
75 | register. | |
76 | */ | |
77 | \f | |
78 | ||
79 | /* Keep statistics of this pass. */ | |
80 | static struct | |
81 | { | |
82 | int moves_inserted; | |
83 | int copies_inserted; | |
84 | int insns_deleted; | |
85 | } stats; | |
86 | ||
87 | /* We need to keep a hash table of expressions. The table entries are of | |
88 | type 'struct expr', and for each expression there is a single linked | |
91275768 | 89 | list of occurrences. */ |
78d140c9 | 90 | |
78d140c9 | 91 | /* Expression elements in the hash table. */ |
92 | struct expr | |
93 | { | |
94 | /* The expression (SET_SRC for expressions, PATTERN for assignments). */ | |
95 | rtx expr; | |
96 | ||
97 | /* The same hash for this entry. */ | |
98 | hashval_t hash; | |
99 | ||
100 | /* List of available occurrence in basic blocks in the function. */ | |
101 | struct occr *avail_occr; | |
102 | }; | |
103 | ||
d9dd21a8 | 104 | /* Hashtable helpers. */ |
105 | ||
106 | struct expr_hasher : typed_noop_remove <expr> | |
107 | { | |
108 | typedef expr value_type; | |
109 | typedef expr compare_type; | |
110 | static inline hashval_t hash (const value_type *); | |
111 | static inline bool equal (const value_type *, const compare_type *); | |
112 | }; | |
113 | ||
114 | ||
115 | /* Hash expression X. | |
116 | DO_NOT_RECORD_P is a boolean indicating if a volatile operand is found | |
117 | or if the expression contains something we don't want to insert in the | |
118 | table. */ | |
119 | ||
120 | static hashval_t | |
121 | hash_expr (rtx x, int *do_not_record_p) | |
122 | { | |
123 | *do_not_record_p = 0; | |
124 | return hash_rtx (x, GET_MODE (x), do_not_record_p, | |
125 | NULL, /*have_reg_qty=*/false); | |
126 | } | |
127 | ||
128 | /* Callback for hashtab. | |
129 | Return the hash value for expression EXP. We don't actually hash | |
130 | here, we just return the cached hash value. */ | |
131 | ||
132 | inline hashval_t | |
133 | expr_hasher::hash (const value_type *exp) | |
134 | { | |
135 | return exp->hash; | |
136 | } | |
137 | ||
138 | /* Callback for hashtab. | |
139 | Return nonzero if exp1 is equivalent to exp2. */ | |
140 | ||
141 | inline bool | |
142 | expr_hasher::equal (const value_type *exp1, const compare_type *exp2) | |
143 | { | |
144 | int equiv_p = exp_equiv_p (exp1->expr, exp2->expr, 0, true); | |
145 | ||
146 | gcc_assert (!equiv_p || exp1->hash == exp2->hash); | |
147 | return equiv_p; | |
148 | } | |
149 | ||
150 | /* The table itself. */ | |
151 | static hash_table <expr_hasher> expr_table; | |
152 | \f | |
153 | ||
78d140c9 | 154 | static struct obstack expr_obstack; |
155 | ||
156 | /* Occurrence of an expression. | |
91275768 | 157 | There is at most one occurrence per basic block. If a pattern appears |
78d140c9 | 158 | more than once, the last appearance is used. */ |
159 | ||
160 | struct occr | |
161 | { | |
162 | /* Next occurrence of this expression. */ | |
163 | struct occr *next; | |
164 | /* The insn that computes the expression. */ | |
165 | rtx insn; | |
166 | /* Nonzero if this [anticipatable] occurrence has been deleted. */ | |
167 | char deleted_p; | |
168 | }; | |
169 | ||
170 | static struct obstack occr_obstack; | |
171 | ||
172 | /* The following structure holds the information about the occurrences of | |
173 | the redundant instructions. */ | |
174 | struct unoccr | |
175 | { | |
176 | struct unoccr *next; | |
177 | edge pred; | |
178 | rtx insn; | |
179 | }; | |
180 | ||
181 | static struct obstack unoccr_obstack; | |
182 | ||
183 | /* Array where each element is the CUID if the insn that last set the hard | |
184 | register with the number of the element, since the start of the current | |
d447762f | 185 | basic block. |
186 | ||
187 | This array is used during the building of the hash table (step 1) to | |
188 | determine if a reg is killed before the end of a basic block. | |
189 | ||
190 | It is also used when eliminating partial redundancies (step 2) to see | |
191 | if a reg was modified since the start of a basic block. */ | |
78d140c9 | 192 | static int *reg_avail_info; |
193 | ||
194 | /* A list of insns that may modify memory within the current basic block. */ | |
195 | struct modifies_mem | |
196 | { | |
197 | rtx insn; | |
198 | struct modifies_mem *next; | |
199 | }; | |
200 | static struct modifies_mem *modifies_mem_list; | |
201 | ||
202 | /* The modifies_mem structs also go on an obstack, only this obstack is | |
203 | freed each time after completing the analysis or transformations on | |
204 | a basic block. So we allocate a dummy modifies_mem_obstack_bottom | |
205 | object on the obstack to keep track of the bottom of the obstack. */ | |
206 | static struct obstack modifies_mem_obstack; | |
207 | static struct modifies_mem *modifies_mem_obstack_bottom; | |
208 | ||
209 | /* Mapping of insn UIDs to CUIDs. | |
210 | CUIDs are like UIDs except they increase monotonically in each basic | |
211 | block, have no gaps, and only apply to real insns. */ | |
212 | static int *uid_cuid; | |
213 | #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)]) | |
214 | \f | |
215 | ||
216 | /* Helpers for memory allocation/freeing. */ | |
217 | static void alloc_mem (void); | |
218 | static void free_mem (void); | |
219 | ||
220 | /* Support for hash table construction and transformations. */ | |
221 | static bool oprs_unchanged_p (rtx, rtx, bool); | |
ce53880e | 222 | static void record_last_reg_set_info (rtx, rtx); |
223 | static void record_last_reg_set_info_regno (rtx, int); | |
78d140c9 | 224 | static void record_last_mem_set_info (rtx); |
81a410b1 | 225 | static void record_last_set_info (rtx, const_rtx, void *); |
d447762f | 226 | static void record_opr_changes (rtx); |
78d140c9 | 227 | |
81a410b1 | 228 | static void find_mem_conflicts (rtx, const_rtx, void *); |
78d140c9 | 229 | static int load_killed_in_block_p (int, rtx, bool); |
230 | static void reset_opr_set_tables (void); | |
231 | ||
232 | /* Hash table support. */ | |
233 | static hashval_t hash_expr (rtx, int *); | |
78d140c9 | 234 | static void insert_expr_in_table (rtx, rtx); |
235 | static struct expr *lookup_expr_in_table (rtx); | |
78d140c9 | 236 | static void dump_hash_table (FILE *); |
237 | ||
238 | /* Helpers for eliminate_partially_redundant_load. */ | |
239 | static bool reg_killed_on_edge (rtx, edge); | |
240 | static bool reg_used_on_edge (rtx, edge); | |
241 | ||
78d140c9 | 242 | static rtx get_avail_load_store_reg (rtx); |
243 | ||
244 | static bool bb_has_well_behaved_predecessors (basic_block); | |
245 | static struct occr* get_bb_avail_insn (basic_block, struct occr *); | |
246 | static void hash_scan_set (rtx); | |
247 | static void compute_hash_table (void); | |
248 | ||
249 | /* The work horses of this pass. */ | |
250 | static void eliminate_partially_redundant_load (basic_block, | |
251 | rtx, | |
252 | struct expr *); | |
253 | static void eliminate_partially_redundant_loads (void); | |
254 | \f | |
255 | ||
256 | /* Allocate memory for the CUID mapping array and register/memory | |
257 | tracking tables. */ | |
258 | ||
259 | static void | |
260 | alloc_mem (void) | |
261 | { | |
262 | int i; | |
263 | basic_block bb; | |
264 | rtx insn; | |
265 | ||
266 | /* Find the largest UID and create a mapping from UIDs to CUIDs. */ | |
4c36ffe6 | 267 | uid_cuid = XCNEWVEC (int, get_max_uid () + 1); |
1539153f | 268 | i = 1; |
fc00614f | 269 | FOR_EACH_BB_FN (bb, cfun) |
78d140c9 | 270 | FOR_BB_INSNS (bb, insn) |
271 | { | |
272 | if (INSN_P (insn)) | |
273 | uid_cuid[INSN_UID (insn)] = i++; | |
274 | else | |
275 | uid_cuid[INSN_UID (insn)] = i; | |
276 | } | |
277 | ||
278 | /* Allocate the available expressions hash table. We don't want to | |
279 | make the hash table too small, but unnecessarily making it too large | |
280 | also doesn't help. The i/4 is a gcse.c relic, and seems like a | |
281 | reasonable choice. */ | |
d9dd21a8 | 282 | expr_table.create (MAX (i / 4, 13)); |
78d140c9 | 283 | |
284 | /* We allocate everything on obstacks because we often can roll back | |
285 | the whole obstack to some point. Freeing obstacks is very fast. */ | |
286 | gcc_obstack_init (&expr_obstack); | |
287 | gcc_obstack_init (&occr_obstack); | |
288 | gcc_obstack_init (&unoccr_obstack); | |
289 | gcc_obstack_init (&modifies_mem_obstack); | |
290 | ||
291 | /* Working array used to track the last set for each register | |
292 | in the current block. */ | |
293 | reg_avail_info = (int *) xmalloc (FIRST_PSEUDO_REGISTER * sizeof (int)); | |
294 | ||
295 | /* Put a dummy modifies_mem object on the modifies_mem_obstack, so we | |
296 | can roll it back in reset_opr_set_tables. */ | |
297 | modifies_mem_obstack_bottom = | |
298 | (struct modifies_mem *) obstack_alloc (&modifies_mem_obstack, | |
299 | sizeof (struct modifies_mem)); | |
300 | } | |
301 | ||
302 | /* Free memory allocated by alloc_mem. */ | |
303 | ||
304 | static void | |
305 | free_mem (void) | |
306 | { | |
307 | free (uid_cuid); | |
308 | ||
d9dd21a8 | 309 | expr_table.dispose (); |
78d140c9 | 310 | |
311 | obstack_free (&expr_obstack, NULL); | |
312 | obstack_free (&occr_obstack, NULL); | |
313 | obstack_free (&unoccr_obstack, NULL); | |
314 | obstack_free (&modifies_mem_obstack, NULL); | |
315 | ||
316 | free (reg_avail_info); | |
317 | } | |
318 | \f | |
319 | ||
78d140c9 | 320 | /* Insert expression X in INSN in the hash TABLE. |
321 | If it is already present, record it as the last occurrence in INSN's | |
322 | basic block. */ | |
323 | ||
324 | static void | |
325 | insert_expr_in_table (rtx x, rtx insn) | |
326 | { | |
327 | int do_not_record_p; | |
328 | hashval_t hash; | |
329 | struct expr *cur_expr, **slot; | |
330 | struct occr *avail_occr, *last_occr = NULL; | |
331 | ||
332 | hash = hash_expr (x, &do_not_record_p); | |
333 | ||
334 | /* Do not insert expression in the table if it contains volatile operands, | |
335 | or if hash_expr determines the expression is something we don't want | |
336 | to or can't handle. */ | |
337 | if (do_not_record_p) | |
338 | return; | |
339 | ||
340 | /* We anticipate that redundant expressions are rare, so for convenience | |
341 | allocate a new hash table element here already and set its fields. | |
342 | If we don't do this, we need a hack with a static struct expr. Anyway, | |
343 | obstack_free is really fast and one more obstack_alloc doesn't hurt if | |
344 | we're going to see more expressions later on. */ | |
345 | cur_expr = (struct expr *) obstack_alloc (&expr_obstack, | |
346 | sizeof (struct expr)); | |
347 | cur_expr->expr = x; | |
348 | cur_expr->hash = hash; | |
349 | cur_expr->avail_occr = NULL; | |
350 | ||
d9dd21a8 | 351 | slot = expr_table.find_slot_with_hash (cur_expr, hash, INSERT); |
48e1416a | 352 | |
78d140c9 | 353 | if (! (*slot)) |
354 | /* The expression isn't found, so insert it. */ | |
355 | *slot = cur_expr; | |
356 | else | |
357 | { | |
358 | /* The expression is already in the table, so roll back the | |
359 | obstack and use the existing table entry. */ | |
360 | obstack_free (&expr_obstack, cur_expr); | |
361 | cur_expr = *slot; | |
362 | } | |
363 | ||
364 | /* Search for another occurrence in the same basic block. */ | |
365 | avail_occr = cur_expr->avail_occr; | |
90bd219d | 366 | while (avail_occr |
367 | && BLOCK_FOR_INSN (avail_occr->insn) != BLOCK_FOR_INSN (insn)) | |
78d140c9 | 368 | { |
369 | /* If an occurrence isn't found, save a pointer to the end of | |
370 | the list. */ | |
371 | last_occr = avail_occr; | |
372 | avail_occr = avail_occr->next; | |
373 | } | |
374 | ||
375 | if (avail_occr) | |
376 | /* Found another instance of the expression in the same basic block. | |
377 | Prefer this occurrence to the currently recorded one. We want | |
378 | the last one in the block and the block is scanned from start | |
379 | to end. */ | |
380 | avail_occr->insn = insn; | |
381 | else | |
382 | { | |
383 | /* First occurrence of this expression in this basic block. */ | |
384 | avail_occr = (struct occr *) obstack_alloc (&occr_obstack, | |
385 | sizeof (struct occr)); | |
386 | ||
387 | /* First occurrence of this expression in any block? */ | |
388 | if (cur_expr->avail_occr == NULL) | |
389 | cur_expr->avail_occr = avail_occr; | |
390 | else | |
391 | last_occr->next = avail_occr; | |
392 | ||
393 | avail_occr->insn = insn; | |
394 | avail_occr->next = NULL; | |
395 | avail_occr->deleted_p = 0; | |
396 | } | |
397 | } | |
398 | \f | |
399 | ||
400 | /* Lookup pattern PAT in the expression hash table. | |
401 | The result is a pointer to the table entry, or NULL if not found. */ | |
402 | ||
403 | static struct expr * | |
404 | lookup_expr_in_table (rtx pat) | |
405 | { | |
406 | int do_not_record_p; | |
407 | struct expr **slot, *tmp_expr; | |
408 | hashval_t hash = hash_expr (pat, &do_not_record_p); | |
409 | ||
410 | if (do_not_record_p) | |
411 | return NULL; | |
412 | ||
413 | tmp_expr = (struct expr *) obstack_alloc (&expr_obstack, | |
414 | sizeof (struct expr)); | |
415 | tmp_expr->expr = pat; | |
416 | tmp_expr->hash = hash; | |
417 | tmp_expr->avail_occr = NULL; | |
418 | ||
d9dd21a8 | 419 | slot = expr_table.find_slot_with_hash (tmp_expr, hash, INSERT); |
78d140c9 | 420 | obstack_free (&expr_obstack, tmp_expr); |
421 | ||
422 | if (!slot) | |
423 | return NULL; | |
424 | else | |
425 | return (*slot); | |
426 | } | |
427 | \f | |
428 | ||
91275768 | 429 | /* Dump all expressions and occurrences that are currently in the |
78d140c9 | 430 | expression hash table to FILE. */ |
431 | ||
432 | /* This helper is called via htab_traverse. */ | |
d9dd21a8 | 433 | int |
434 | dump_expr_hash_table_entry (expr **slot, FILE *file) | |
78d140c9 | 435 | { |
d9dd21a8 | 436 | struct expr *exprs = *slot; |
78d140c9 | 437 | struct occr *occr; |
438 | ||
439 | fprintf (file, "expr: "); | |
d9dd21a8 | 440 | print_rtl (file, exprs->expr); |
441 | fprintf (file,"\nhashcode: %u\n", exprs->hash); | |
4133d091 | 442 | fprintf (file,"list of occurrences:\n"); |
d9dd21a8 | 443 | occr = exprs->avail_occr; |
78d140c9 | 444 | while (occr) |
445 | { | |
446 | rtx insn = occr->insn; | |
447 | print_rtl_single (file, insn); | |
448 | fprintf (file, "\n"); | |
449 | occr = occr->next; | |
450 | } | |
451 | fprintf (file, "\n"); | |
452 | return 1; | |
453 | } | |
454 | ||
455 | static void | |
456 | dump_hash_table (FILE *file) | |
457 | { | |
458 | fprintf (file, "\n\nexpression hash table\n"); | |
459 | fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n", | |
d9dd21a8 | 460 | (long) expr_table.size (), |
461 | (long) expr_table.elements (), | |
462 | expr_table.collisions ()); | |
463 | if (expr_table.elements () > 0) | |
78d140c9 | 464 | { |
465 | fprintf (file, "\n\ntable entries:\n"); | |
d9dd21a8 | 466 | expr_table.traverse <FILE *, dump_expr_hash_table_entry> (file); |
78d140c9 | 467 | } |
468 | fprintf (file, "\n"); | |
469 | } | |
470 | \f | |
20128b13 | 471 | /* Return true if register X is recorded as being set by an instruction |
472 | whose CUID is greater than the one given. */ | |
473 | ||
474 | static bool | |
475 | reg_changed_after_insn_p (rtx x, int cuid) | |
476 | { | |
477 | unsigned int regno, end_regno; | |
478 | ||
479 | regno = REGNO (x); | |
480 | end_regno = END_HARD_REGNO (x); | |
481 | do | |
482 | if (reg_avail_info[regno] > cuid) | |
483 | return true; | |
484 | while (++regno < end_regno); | |
485 | return false; | |
486 | } | |
78d140c9 | 487 | |
d447762f | 488 | /* Return nonzero if the operands of expression X are unchanged |
489 | 1) from the start of INSN's basic block up to but not including INSN | |
490 | if AFTER_INSN is false, or | |
491 | 2) from INSN to the end of INSN's basic block if AFTER_INSN is true. */ | |
78d140c9 | 492 | |
493 | static bool | |
494 | oprs_unchanged_p (rtx x, rtx insn, bool after_insn) | |
495 | { | |
496 | int i, j; | |
497 | enum rtx_code code; | |
498 | const char *fmt; | |
499 | ||
500 | if (x == 0) | |
501 | return 1; | |
502 | ||
503 | code = GET_CODE (x); | |
504 | switch (code) | |
505 | { | |
506 | case REG: | |
78d140c9 | 507 | /* We are called after register allocation. */ |
876760f6 | 508 | gcc_assert (REGNO (x) < FIRST_PSEUDO_REGISTER); |
78d140c9 | 509 | if (after_insn) |
20128b13 | 510 | return !reg_changed_after_insn_p (x, INSN_CUID (insn) - 1); |
78d140c9 | 511 | else |
20128b13 | 512 | return !reg_changed_after_insn_p (x, 0); |
78d140c9 | 513 | |
514 | case MEM: | |
515 | if (load_killed_in_block_p (INSN_CUID (insn), x, after_insn)) | |
516 | return 0; | |
517 | else | |
518 | return oprs_unchanged_p (XEXP (x, 0), insn, after_insn); | |
519 | ||
520 | case PC: | |
521 | case CC0: /*FIXME*/ | |
522 | case CONST: | |
0349edce | 523 | CASE_CONST_ANY: |
78d140c9 | 524 | case SYMBOL_REF: |
525 | case LABEL_REF: | |
526 | case ADDR_VEC: | |
527 | case ADDR_DIFF_VEC: | |
528 | return 1; | |
529 | ||
530 | case PRE_DEC: | |
531 | case PRE_INC: | |
532 | case POST_DEC: | |
533 | case POST_INC: | |
534 | case PRE_MODIFY: | |
535 | case POST_MODIFY: | |
536 | if (after_insn) | |
537 | return 0; | |
538 | break; | |
539 | ||
540 | default: | |
541 | break; | |
542 | } | |
543 | ||
544 | for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--) | |
545 | { | |
546 | if (fmt[i] == 'e') | |
547 | { | |
548 | if (! oprs_unchanged_p (XEXP (x, i), insn, after_insn)) | |
549 | return 0; | |
550 | } | |
551 | else if (fmt[i] == 'E') | |
552 | for (j = 0; j < XVECLEN (x, i); j++) | |
553 | if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, after_insn)) | |
554 | return 0; | |
555 | } | |
556 | ||
557 | return 1; | |
558 | } | |
559 | \f | |
560 | ||
561 | /* Used for communication between find_mem_conflicts and | |
562 | load_killed_in_block_p. Nonzero if find_mem_conflicts finds a | |
563 | conflict between two memory references. | |
564 | This is a bit of a hack to work around the limitations of note_stores. */ | |
565 | static int mems_conflict_p; | |
566 | ||
567 | /* DEST is the output of an instruction. If it is a memory reference, and | |
568 | possibly conflicts with the load found in DATA, then set mems_conflict_p | |
569 | to a nonzero value. */ | |
570 | ||
571 | static void | |
81a410b1 | 572 | find_mem_conflicts (rtx dest, const_rtx setter ATTRIBUTE_UNUSED, |
78d140c9 | 573 | void *data) |
574 | { | |
575 | rtx mem_op = (rtx) data; | |
576 | ||
577 | while (GET_CODE (dest) == SUBREG | |
578 | || GET_CODE (dest) == ZERO_EXTRACT | |
78d140c9 | 579 | || GET_CODE (dest) == STRICT_LOW_PART) |
580 | dest = XEXP (dest, 0); | |
581 | ||
582 | /* If DEST is not a MEM, then it will not conflict with the load. Note | |
583 | that function calls are assumed to clobber memory, but are handled | |
584 | elsewhere. */ | |
585 | if (! MEM_P (dest)) | |
586 | return; | |
587 | ||
376a287d | 588 | if (true_dependence (dest, GET_MODE (dest), mem_op)) |
78d140c9 | 589 | mems_conflict_p = 1; |
590 | } | |
591 | \f | |
592 | ||
593 | /* Return nonzero if the expression in X (a memory reference) is killed | |
d447762f | 594 | in the current basic block before (if AFTER_INSN is false) or after |
595 | (if AFTER_INSN is true) the insn with the CUID in UID_LIMIT. | |
596 | ||
597 | This function assumes that the modifies_mem table is flushed when | |
598 | the hash table construction or redundancy elimination phases start | |
599 | processing a new basic block. */ | |
78d140c9 | 600 | |
601 | static int | |
602 | load_killed_in_block_p (int uid_limit, rtx x, bool after_insn) | |
603 | { | |
604 | struct modifies_mem *list_entry = modifies_mem_list; | |
605 | ||
606 | while (list_entry) | |
607 | { | |
608 | rtx setter = list_entry->insn; | |
609 | ||
610 | /* Ignore entries in the list that do not apply. */ | |
611 | if ((after_insn | |
612 | && INSN_CUID (setter) < uid_limit) | |
613 | || (! after_insn | |
614 | && INSN_CUID (setter) > uid_limit)) | |
615 | { | |
616 | list_entry = list_entry->next; | |
617 | continue; | |
618 | } | |
619 | ||
620 | /* If SETTER is a call everything is clobbered. Note that calls | |
621 | to pure functions are never put on the list, so we need not | |
622 | worry about them. */ | |
623 | if (CALL_P (setter)) | |
624 | return 1; | |
625 | ||
626 | /* SETTER must be an insn of some kind that sets memory. Call | |
627 | note_stores to examine each hunk of memory that is modified. | |
628 | It will set mems_conflict_p to nonzero if there may be a | |
629 | conflict between X and SETTER. */ | |
630 | mems_conflict_p = 0; | |
631 | note_stores (PATTERN (setter), find_mem_conflicts, x); | |
632 | if (mems_conflict_p) | |
633 | return 1; | |
634 | ||
635 | list_entry = list_entry->next; | |
636 | } | |
637 | return 0; | |
638 | } | |
639 | \f | |
640 | ||
641 | /* Record register first/last/block set information for REGNO in INSN. */ | |
642 | ||
d447762f | 643 | static inline void |
ce53880e | 644 | record_last_reg_set_info (rtx insn, rtx reg) |
645 | { | |
646 | unsigned int regno, end_regno; | |
647 | ||
648 | regno = REGNO (reg); | |
649 | end_regno = END_HARD_REGNO (reg); | |
650 | do | |
651 | reg_avail_info[regno] = INSN_CUID (insn); | |
652 | while (++regno < end_regno); | |
653 | } | |
654 | ||
655 | static inline void | |
656 | record_last_reg_set_info_regno (rtx insn, int regno) | |
78d140c9 | 657 | { |
658 | reg_avail_info[regno] = INSN_CUID (insn); | |
659 | } | |
660 | ||
661 | ||
662 | /* Record memory modification information for INSN. We do not actually care | |
663 | about the memory location(s) that are set, or even how they are set (consider | |
664 | a CALL_INSN). We merely need to record which insns modify memory. */ | |
665 | ||
666 | static void | |
667 | record_last_mem_set_info (rtx insn) | |
668 | { | |
669 | struct modifies_mem *list_entry; | |
670 | ||
671 | list_entry = (struct modifies_mem *) obstack_alloc (&modifies_mem_obstack, | |
672 | sizeof (struct modifies_mem)); | |
673 | list_entry->insn = insn; | |
674 | list_entry->next = modifies_mem_list; | |
675 | modifies_mem_list = list_entry; | |
676 | } | |
677 | ||
678 | /* Called from compute_hash_table via note_stores to handle one | |
679 | SET or CLOBBER in an insn. DATA is really the instruction in which | |
680 | the SET is taking place. */ | |
681 | ||
682 | static void | |
81a410b1 | 683 | record_last_set_info (rtx dest, const_rtx setter ATTRIBUTE_UNUSED, void *data) |
78d140c9 | 684 | { |
685 | rtx last_set_insn = (rtx) data; | |
686 | ||
687 | if (GET_CODE (dest) == SUBREG) | |
688 | dest = SUBREG_REG (dest); | |
689 | ||
690 | if (REG_P (dest)) | |
ce53880e | 691 | record_last_reg_set_info (last_set_insn, dest); |
5630a23e | 692 | else if (MEM_P (dest)) |
693 | { | |
694 | /* Ignore pushes, they don't clobber memory. They may still | |
695 | clobber the stack pointer though. Some targets do argument | |
696 | pushes without adding REG_INC notes. See e.g. PR25196, | |
697 | where a pushsi2 on i386 doesn't have REG_INC notes. Note | |
698 | such changes here too. */ | |
699 | if (! push_operand (dest, GET_MODE (dest))) | |
700 | record_last_mem_set_info (last_set_insn); | |
701 | else | |
ce53880e | 702 | record_last_reg_set_info_regno (last_set_insn, STACK_POINTER_REGNUM); |
5630a23e | 703 | } |
78d140c9 | 704 | } |
d447762f | 705 | |
78d140c9 | 706 | |
707 | /* Reset tables used to keep track of what's still available since the | |
708 | start of the block. */ | |
709 | ||
710 | static void | |
711 | reset_opr_set_tables (void) | |
712 | { | |
713 | memset (reg_avail_info, 0, FIRST_PSEUDO_REGISTER * sizeof (int)); | |
714 | obstack_free (&modifies_mem_obstack, modifies_mem_obstack_bottom); | |
715 | modifies_mem_list = NULL; | |
716 | } | |
d447762f | 717 | \f |
78d140c9 | 718 | |
719 | /* Record things set by INSN. | |
720 | This data is used by oprs_unchanged_p. */ | |
721 | ||
722 | static void | |
d447762f | 723 | record_opr_changes (rtx insn) |
78d140c9 | 724 | { |
d447762f | 725 | rtx note; |
78d140c9 | 726 | |
d447762f | 727 | /* Find all stores and record them. */ |
728 | note_stores (PATTERN (insn), record_last_set_info, insn); | |
78d140c9 | 729 | |
d447762f | 730 | /* Also record autoincremented REGs for this insn as changed. */ |
731 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) | |
732 | if (REG_NOTE_KIND (note) == REG_INC) | |
ce53880e | 733 | record_last_reg_set_info (insn, XEXP (note, 0)); |
78d140c9 | 734 | |
d447762f | 735 | /* Finally, if this is a call, record all call clobbers. */ |
736 | if (CALL_P (insn)) | |
737 | { | |
ce53880e | 738 | unsigned int regno; |
20128b13 | 739 | rtx link, x; |
24ec6636 | 740 | hard_reg_set_iterator hrsi; |
741 | EXECUTE_IF_SET_IN_HARD_REG_SET (regs_invalidated_by_call, 0, regno, hrsi) | |
742 | record_last_reg_set_info_regno (insn, regno); | |
78d140c9 | 743 | |
20128b13 | 744 | for (link = CALL_INSN_FUNCTION_USAGE (insn); link; link = XEXP (link, 1)) |
745 | if (GET_CODE (XEXP (link, 0)) == CLOBBER) | |
746 | { | |
747 | x = XEXP (XEXP (link, 0), 0); | |
748 | if (REG_P (x)) | |
749 | { | |
750 | gcc_assert (HARD_REGISTER_P (x)); | |
ce53880e | 751 | record_last_reg_set_info (insn, x); |
20128b13 | 752 | } |
753 | } | |
754 | ||
9c2a0c05 | 755 | if (! RTL_CONST_OR_PURE_CALL_P (insn)) |
d447762f | 756 | record_last_mem_set_info (insn); |
757 | } | |
78d140c9 | 758 | } |
759 | \f | |
760 | ||
761 | /* Scan the pattern of INSN and add an entry to the hash TABLE. | |
762 | After reload we are interested in loads/stores only. */ | |
763 | ||
764 | static void | |
765 | hash_scan_set (rtx insn) | |
766 | { | |
767 | rtx pat = PATTERN (insn); | |
768 | rtx src = SET_SRC (pat); | |
769 | rtx dest = SET_DEST (pat); | |
770 | ||
771 | /* We are only interested in loads and stores. */ | |
772 | if (! MEM_P (src) && ! MEM_P (dest)) | |
773 | return; | |
774 | ||
775 | /* Don't mess with jumps and nops. */ | |
776 | if (JUMP_P (insn) || set_noop_p (pat)) | |
777 | return; | |
778 | ||
78d140c9 | 779 | if (REG_P (dest)) |
780 | { | |
d447762f | 781 | if (/* Don't CSE something if we can't do a reg/reg copy. */ |
78d140c9 | 782 | can_copy_p (GET_MODE (dest)) |
783 | /* Is SET_SRC something we want to gcse? */ | |
784 | && general_operand (src, GET_MODE (src)) | |
868e8f12 | 785 | #ifdef STACK_REGS |
786 | /* Never consider insns touching the register stack. It may | |
787 | create situations that reg-stack cannot handle (e.g. a stack | |
788 | register live across an abnormal edge). */ | |
789 | && (REGNO (dest) < FIRST_STACK_REG || REGNO (dest) > LAST_STACK_REG) | |
790 | #endif | |
78d140c9 | 791 | /* An expression is not available if its operands are |
792 | subsequently modified, including this insn. */ | |
793 | && oprs_unchanged_p (src, insn, true)) | |
794 | { | |
795 | insert_expr_in_table (src, insn); | |
796 | } | |
797 | } | |
798 | else if (REG_P (src)) | |
799 | { | |
800 | /* Only record sets of pseudo-regs in the hash table. */ | |
d447762f | 801 | if (/* Don't CSE something if we can't do a reg/reg copy. */ |
78d140c9 | 802 | can_copy_p (GET_MODE (src)) |
803 | /* Is SET_DEST something we want to gcse? */ | |
804 | && general_operand (dest, GET_MODE (dest)) | |
868e8f12 | 805 | #ifdef STACK_REGS |
806 | /* As above for STACK_REGS. */ | |
807 | && (REGNO (src) < FIRST_STACK_REG || REGNO (src) > LAST_STACK_REG) | |
808 | #endif | |
78d140c9 | 809 | && ! (flag_float_store && FLOAT_MODE_P (GET_MODE (dest))) |
810 | /* Check if the memory expression is killed after insn. */ | |
811 | && ! load_killed_in_block_p (INSN_CUID (insn) + 1, dest, true) | |
812 | && oprs_unchanged_p (XEXP (dest, 0), insn, true)) | |
813 | { | |
814 | insert_expr_in_table (dest, insn); | |
815 | } | |
816 | } | |
817 | } | |
818 | \f | |
d447762f | 819 | |
78d140c9 | 820 | /* Create hash table of memory expressions available at end of basic |
d447762f | 821 | blocks. Basically you should think of this hash table as the |
822 | representation of AVAIL_OUT. This is the set of expressions that | |
823 | is generated in a basic block and not killed before the end of the | |
824 | same basic block. Notice that this is really a local computation. */ | |
78d140c9 | 825 | |
826 | static void | |
827 | compute_hash_table (void) | |
828 | { | |
829 | basic_block bb; | |
830 | ||
fc00614f | 831 | FOR_EACH_BB_FN (bb, cfun) |
78d140c9 | 832 | { |
833 | rtx insn; | |
78d140c9 | 834 | |
835 | /* First pass over the instructions records information used to | |
d447762f | 836 | determine when registers and memory are last set. |
837 | Since we compute a "local" AVAIL_OUT, reset the tables that | |
838 | help us keep track of what has been modified since the start | |
839 | of the block. */ | |
840 | reset_opr_set_tables (); | |
78d140c9 | 841 | FOR_BB_INSNS (bb, insn) |
842 | { | |
d447762f | 843 | if (INSN_P (insn)) |
844 | record_opr_changes (insn); | |
845 | } | |
78d140c9 | 846 | |
d447762f | 847 | /* The next pass actually builds the hash table. */ |
78d140c9 | 848 | FOR_BB_INSNS (bb, insn) |
849 | if (INSN_P (insn) && GET_CODE (PATTERN (insn)) == SET) | |
850 | hash_scan_set (insn); | |
851 | } | |
852 | } | |
853 | \f | |
854 | ||
855 | /* Check if register REG is killed in any insn waiting to be inserted on | |
856 | edge E. This function is required to check that our data flow analysis | |
857 | is still valid prior to commit_edge_insertions. */ | |
858 | ||
859 | static bool | |
860 | reg_killed_on_edge (rtx reg, edge e) | |
861 | { | |
862 | rtx insn; | |
863 | ||
864 | for (insn = e->insns.r; insn; insn = NEXT_INSN (insn)) | |
865 | if (INSN_P (insn) && reg_set_p (reg, insn)) | |
866 | return true; | |
867 | ||
868 | return false; | |
869 | } | |
870 | ||
871 | /* Similar to above - check if register REG is used in any insn waiting | |
872 | to be inserted on edge E. | |
873 | Assumes no such insn can be a CALL_INSN; if so call reg_used_between_p | |
874 | with PREV(insn),NEXT(insn) instead of calling reg_overlap_mentioned_p. */ | |
875 | ||
876 | static bool | |
877 | reg_used_on_edge (rtx reg, edge e) | |
878 | { | |
879 | rtx insn; | |
880 | ||
881 | for (insn = e->insns.r; insn; insn = NEXT_INSN (insn)) | |
882 | if (INSN_P (insn) && reg_overlap_mentioned_p (reg, PATTERN (insn))) | |
883 | return true; | |
884 | ||
885 | return false; | |
886 | } | |
887 | \f | |
78d140c9 | 888 | /* Return the loaded/stored register of a load/store instruction. */ |
889 | ||
890 | static rtx | |
891 | get_avail_load_store_reg (rtx insn) | |
892 | { | |
876760f6 | 893 | if (REG_P (SET_DEST (PATTERN (insn)))) |
894 | /* A load. */ | |
9af5ce0c | 895 | return SET_DEST (PATTERN (insn)); |
876760f6 | 896 | else |
897 | { | |
898 | /* A store. */ | |
899 | gcc_assert (REG_P (SET_SRC (PATTERN (insn)))); | |
900 | return SET_SRC (PATTERN (insn)); | |
901 | } | |
78d140c9 | 902 | } |
903 | ||
904 | /* Return nonzero if the predecessors of BB are "well behaved". */ | |
905 | ||
906 | static bool | |
907 | bb_has_well_behaved_predecessors (basic_block bb) | |
908 | { | |
909 | edge pred; | |
cd665a06 | 910 | edge_iterator ei; |
78d140c9 | 911 | |
4c43a998 | 912 | if (EDGE_COUNT (bb->preds) == 0) |
78d140c9 | 913 | return false; |
914 | ||
cd665a06 | 915 | FOR_EACH_EDGE (pred, ei, bb->preds) |
78d140c9 | 916 | { |
917 | if ((pred->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (pred)) | |
918 | return false; | |
919 | ||
4c43a998 | 920 | if ((pred->flags & EDGE_ABNORMAL_CALL) && cfun->has_nonlocal_label) |
921 | return false; | |
922 | ||
91f71fa3 | 923 | if (tablejump_p (BB_END (pred->src), NULL, NULL)) |
78d140c9 | 924 | return false; |
925 | } | |
926 | return true; | |
927 | } | |
928 | ||
929 | ||
930 | /* Search for the occurrences of expression in BB. */ | |
931 | ||
932 | static struct occr* | |
933 | get_bb_avail_insn (basic_block bb, struct occr *occr) | |
934 | { | |
935 | for (; occr != NULL; occr = occr->next) | |
936 | if (BLOCK_FOR_INSN (occr->insn) == bb) | |
937 | return occr; | |
938 | return NULL; | |
939 | } | |
940 | ||
941 | ||
942 | /* This handles the case where several stores feed a partially redundant | |
943 | load. It checks if the redundancy elimination is possible and if it's | |
d447762f | 944 | worth it. |
945 | ||
946 | Redundancy elimination is possible if, | |
947 | 1) None of the operands of an insn have been modified since the start | |
948 | of the current basic block. | |
949 | 2) In any predecessor of the current basic block, the same expression | |
950 | is generated. | |
951 | ||
952 | See the function body for the heuristics that determine if eliminating | |
953 | a redundancy is also worth doing, assuming it is possible. */ | |
78d140c9 | 954 | |
955 | static void | |
956 | eliminate_partially_redundant_load (basic_block bb, rtx insn, | |
957 | struct expr *expr) | |
958 | { | |
959 | edge pred; | |
960 | rtx avail_insn = NULL_RTX; | |
961 | rtx avail_reg; | |
962 | rtx dest, pat; | |
963 | struct occr *a_occr; | |
964 | struct unoccr *occr, *avail_occrs = NULL; | |
965 | struct unoccr *unoccr, *unavail_occrs = NULL, *rollback_unoccr = NULL; | |
966 | int npred_ok = 0; | |
967 | gcov_type ok_count = 0; /* Redundant load execution count. */ | |
968 | gcov_type critical_count = 0; /* Execution count of critical edges. */ | |
cd665a06 | 969 | edge_iterator ei; |
b0596095 | 970 | bool critical_edge_split = false; |
78d140c9 | 971 | |
972 | /* The execution count of the loads to be added to make the | |
973 | load fully redundant. */ | |
974 | gcov_type not_ok_count = 0; | |
975 | basic_block pred_bb; | |
976 | ||
977 | pat = PATTERN (insn); | |
978 | dest = SET_DEST (pat); | |
979 | ||
980 | /* Check that the loaded register is not used, set, or killed from the | |
981 | beginning of the block. */ | |
20128b13 | 982 | if (reg_changed_after_insn_p (dest, 0) |
983 | || reg_used_between_p (dest, PREV_INSN (BB_HEAD (bb)), insn)) | |
78d140c9 | 984 | return; |
985 | ||
986 | /* Check potential for replacing load with copy for predecessors. */ | |
cd665a06 | 987 | FOR_EACH_EDGE (pred, ei, bb->preds) |
78d140c9 | 988 | { |
989 | rtx next_pred_bb_end; | |
990 | ||
991 | avail_insn = NULL_RTX; | |
b0596095 | 992 | avail_reg = NULL_RTX; |
78d140c9 | 993 | pred_bb = pred->src; |
994 | next_pred_bb_end = NEXT_INSN (BB_END (pred_bb)); | |
995 | for (a_occr = get_bb_avail_insn (pred_bb, expr->avail_occr); a_occr; | |
996 | a_occr = get_bb_avail_insn (pred_bb, a_occr->next)) | |
997 | { | |
998 | /* Check if the loaded register is not used. */ | |
999 | avail_insn = a_occr->insn; | |
876760f6 | 1000 | avail_reg = get_avail_load_store_reg (avail_insn); |
1001 | gcc_assert (avail_reg); | |
48e1416a | 1002 | |
78d140c9 | 1003 | /* Make sure we can generate a move from register avail_reg to |
1004 | dest. */ | |
1005 | extract_insn (gen_move_insn (copy_rtx (dest), | |
1006 | copy_rtx (avail_reg))); | |
1007 | if (! constrain_operands (1) | |
1008 | || reg_killed_on_edge (avail_reg, pred) | |
1009 | || reg_used_on_edge (dest, pred)) | |
1010 | { | |
1011 | avail_insn = NULL; | |
1012 | continue; | |
1013 | } | |
20128b13 | 1014 | if (!reg_set_between_p (avail_reg, avail_insn, next_pred_bb_end)) |
78d140c9 | 1015 | /* AVAIL_INSN remains non-null. */ |
1016 | break; | |
1017 | else | |
1018 | avail_insn = NULL; | |
1019 | } | |
1020 | ||
1021 | if (EDGE_CRITICAL_P (pred)) | |
1022 | critical_count += pred->count; | |
1023 | ||
1024 | if (avail_insn != NULL_RTX) | |
1025 | { | |
1026 | npred_ok++; | |
1027 | ok_count += pred->count; | |
b0596095 | 1028 | if (! set_noop_p (PATTERN (gen_move_insn (copy_rtx (dest), |
1029 | copy_rtx (avail_reg))))) | |
1030 | { | |
1031 | /* Check if there is going to be a split. */ | |
1032 | if (EDGE_CRITICAL_P (pred)) | |
1033 | critical_edge_split = true; | |
1034 | } | |
1035 | else /* Its a dead move no need to generate. */ | |
1036 | continue; | |
78d140c9 | 1037 | occr = (struct unoccr *) obstack_alloc (&unoccr_obstack, |
beab9d47 | 1038 | sizeof (struct unoccr)); |
78d140c9 | 1039 | occr->insn = avail_insn; |
1040 | occr->pred = pred; | |
1041 | occr->next = avail_occrs; | |
1042 | avail_occrs = occr; | |
1043 | if (! rollback_unoccr) | |
1044 | rollback_unoccr = occr; | |
1045 | } | |
1046 | else | |
1047 | { | |
7063afc3 | 1048 | /* Adding a load on a critical edge will cause a split. */ |
b0596095 | 1049 | if (EDGE_CRITICAL_P (pred)) |
1050 | critical_edge_split = true; | |
78d140c9 | 1051 | not_ok_count += pred->count; |
1052 | unoccr = (struct unoccr *) obstack_alloc (&unoccr_obstack, | |
1053 | sizeof (struct unoccr)); | |
1054 | unoccr->insn = NULL_RTX; | |
1055 | unoccr->pred = pred; | |
1056 | unoccr->next = unavail_occrs; | |
1057 | unavail_occrs = unoccr; | |
1058 | if (! rollback_unoccr) | |
1059 | rollback_unoccr = unoccr; | |
1060 | } | |
1061 | } | |
1062 | ||
1063 | if (/* No load can be replaced by copy. */ | |
1064 | npred_ok == 0 | |
48e1416a | 1065 | /* Prevent exploding the code. */ |
0bfd8d5c | 1066 | || (optimize_bb_for_size_p (bb) && npred_ok > 1) |
48e1416a | 1067 | /* If we don't have profile information we cannot tell if splitting |
b0596095 | 1068 | a critical edge is profitable or not so don't do it. */ |
1069 | || ((! profile_info || ! flag_branch_probabilities | |
1070 | || targetm.cannot_modify_jumps_p ()) | |
1071 | && critical_edge_split)) | |
78d140c9 | 1072 | goto cleanup; |
1073 | ||
1074 | /* Check if it's worth applying the partial redundancy elimination. */ | |
1075 | if (ok_count < GCSE_AFTER_RELOAD_PARTIAL_FRACTION * not_ok_count) | |
1076 | goto cleanup; | |
1077 | if (ok_count < GCSE_AFTER_RELOAD_CRITICAL_FRACTION * critical_count) | |
1078 | goto cleanup; | |
1079 | ||
1080 | /* Generate moves to the loaded register from where | |
1081 | the memory is available. */ | |
1082 | for (occr = avail_occrs; occr; occr = occr->next) | |
1083 | { | |
1084 | avail_insn = occr->insn; | |
1085 | pred = occr->pred; | |
1086 | /* Set avail_reg to be the register having the value of the | |
1087 | memory. */ | |
1088 | avail_reg = get_avail_load_store_reg (avail_insn); | |
876760f6 | 1089 | gcc_assert (avail_reg); |
78d140c9 | 1090 | |
1091 | insert_insn_on_edge (gen_move_insn (copy_rtx (dest), | |
1092 | copy_rtx (avail_reg)), | |
1093 | pred); | |
1094 | stats.moves_inserted++; | |
1095 | ||
1096 | if (dump_file) | |
1097 | fprintf (dump_file, | |
1098 | "generating move from %d to %d on edge from %d to %d\n", | |
1099 | REGNO (avail_reg), | |
1100 | REGNO (dest), | |
1101 | pred->src->index, | |
1102 | pred->dest->index); | |
1103 | } | |
1104 | ||
1105 | /* Regenerate loads where the memory is unavailable. */ | |
1106 | for (unoccr = unavail_occrs; unoccr; unoccr = unoccr->next) | |
1107 | { | |
1108 | pred = unoccr->pred; | |
1109 | insert_insn_on_edge (copy_insn (PATTERN (insn)), pred); | |
1110 | stats.copies_inserted++; | |
1111 | ||
1112 | if (dump_file) | |
1113 | { | |
1114 | fprintf (dump_file, | |
1115 | "generating on edge from %d to %d a copy of load: ", | |
1116 | pred->src->index, | |
1117 | pred->dest->index); | |
1118 | print_rtl (dump_file, PATTERN (insn)); | |
1119 | fprintf (dump_file, "\n"); | |
1120 | } | |
1121 | } | |
1122 | ||
1123 | /* Delete the insn if it is not available in this block and mark it | |
1124 | for deletion if it is available. If insn is available it may help | |
1125 | discover additional redundancies, so mark it for later deletion. */ | |
1126 | for (a_occr = get_bb_avail_insn (bb, expr->avail_occr); | |
1127 | a_occr && (a_occr->insn != insn); | |
3c802a1e | 1128 | a_occr = get_bb_avail_insn (bb, a_occr->next)) |
1129 | ; | |
78d140c9 | 1130 | |
1131 | if (!a_occr) | |
b0596095 | 1132 | { |
1133 | stats.insns_deleted++; | |
1134 | ||
1135 | if (dump_file) | |
1136 | { | |
1137 | fprintf (dump_file, "deleting insn:\n"); | |
1138 | print_rtl_single (dump_file, insn); | |
1139 | fprintf (dump_file, "\n"); | |
1140 | } | |
1141 | delete_insn (insn); | |
1142 | } | |
78d140c9 | 1143 | else |
1144 | a_occr->deleted_p = 1; | |
1145 | ||
1146 | cleanup: | |
1147 | if (rollback_unoccr) | |
1148 | obstack_free (&unoccr_obstack, rollback_unoccr); | |
1149 | } | |
1150 | ||
1151 | /* Performing the redundancy elimination as described before. */ | |
1152 | ||
1153 | static void | |
1154 | eliminate_partially_redundant_loads (void) | |
1155 | { | |
1156 | rtx insn; | |
1157 | basic_block bb; | |
1158 | ||
1159 | /* Note we start at block 1. */ | |
1160 | ||
34154e27 | 1161 | if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
78d140c9 | 1162 | return; |
1163 | ||
1164 | FOR_BB_BETWEEN (bb, | |
34154e27 | 1165 | ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb->next_bb, |
1166 | EXIT_BLOCK_PTR_FOR_FN (cfun), | |
78d140c9 | 1167 | next_bb) |
1168 | { | |
d447762f | 1169 | /* Don't try anything on basic blocks with strange predecessors. */ |
78d140c9 | 1170 | if (! bb_has_well_behaved_predecessors (bb)) |
1171 | continue; | |
1172 | ||
d447762f | 1173 | /* Do not try anything on cold basic blocks. */ |
f29b326e | 1174 | if (optimize_bb_for_size_p (bb)) |
78d140c9 | 1175 | continue; |
1176 | ||
d447762f | 1177 | /* Reset the table of things changed since the start of the current |
1178 | basic block. */ | |
78d140c9 | 1179 | reset_opr_set_tables (); |
1180 | ||
d447762f | 1181 | /* Look at all insns in the current basic block and see if there are |
1182 | any loads in it that we can record. */ | |
78d140c9 | 1183 | FOR_BB_INSNS (bb, insn) |
1184 | { | |
1185 | /* Is it a load - of the form (set (reg) (mem))? */ | |
1186 | if (NONJUMP_INSN_P (insn) | |
1187 | && GET_CODE (PATTERN (insn)) == SET | |
1188 | && REG_P (SET_DEST (PATTERN (insn))) | |
1189 | && MEM_P (SET_SRC (PATTERN (insn)))) | |
1190 | { | |
1191 | rtx pat = PATTERN (insn); | |
1192 | rtx src = SET_SRC (pat); | |
1193 | struct expr *expr; | |
1194 | ||
1195 | if (!MEM_VOLATILE_P (src) | |
1196 | && GET_MODE (src) != BLKmode | |
1197 | && general_operand (src, GET_MODE (src)) | |
1198 | /* Are the operands unchanged since the start of the | |
1199 | block? */ | |
1200 | && oprs_unchanged_p (src, insn, false) | |
cbeb677e | 1201 | && !(cfun->can_throw_non_call_exceptions && may_trap_p (src)) |
78d140c9 | 1202 | && !side_effects_p (src) |
1203 | /* Is the expression recorded? */ | |
1204 | && (expr = lookup_expr_in_table (src)) != NULL) | |
1205 | { | |
1206 | /* We now have a load (insn) and an available memory at | |
1207 | its BB start (expr). Try to remove the loads if it is | |
1208 | redundant. */ | |
1209 | eliminate_partially_redundant_load (bb, insn, expr); | |
1210 | } | |
1211 | } | |
1212 | ||
d447762f | 1213 | /* Keep track of everything modified by this insn, so that we |
1214 | know what has been modified since the start of the current | |
1215 | basic block. */ | |
78d140c9 | 1216 | if (INSN_P (insn)) |
d447762f | 1217 | record_opr_changes (insn); |
78d140c9 | 1218 | } |
1219 | } | |
1220 | ||
1221 | commit_edge_insertions (); | |
1222 | } | |
1223 | ||
1224 | /* Go over the expression hash table and delete insns that were | |
1225 | marked for later deletion. */ | |
1226 | ||
1227 | /* This helper is called via htab_traverse. */ | |
d9dd21a8 | 1228 | int |
1229 | delete_redundant_insns_1 (expr **slot, void *data ATTRIBUTE_UNUSED) | |
78d140c9 | 1230 | { |
d9dd21a8 | 1231 | struct expr *exprs = *slot; |
78d140c9 | 1232 | struct occr *occr; |
1233 | ||
d9dd21a8 | 1234 | for (occr = exprs->avail_occr; occr != NULL; occr = occr->next) |
78d140c9 | 1235 | { |
3072d30e | 1236 | if (occr->deleted_p && dbg_cnt (gcse2_delete)) |
78d140c9 | 1237 | { |
1238 | delete_insn (occr->insn); | |
1239 | stats.insns_deleted++; | |
1240 | ||
1241 | if (dump_file) | |
1242 | { | |
1243 | fprintf (dump_file, "deleting insn:\n"); | |
1244 | print_rtl_single (dump_file, occr->insn); | |
1245 | fprintf (dump_file, "\n"); | |
1246 | } | |
1247 | } | |
1248 | } | |
1249 | ||
1250 | return 1; | |
1251 | } | |
1252 | ||
1253 | static void | |
1254 | delete_redundant_insns (void) | |
1255 | { | |
d9dd21a8 | 1256 | expr_table.traverse <void *, delete_redundant_insns_1> (NULL); |
78d140c9 | 1257 | if (dump_file) |
1258 | fprintf (dump_file, "\n"); | |
1259 | } | |
1260 | ||
1261 | /* Main entry point of the GCSE after reload - clean some redundant loads | |
1262 | due to spilling. */ | |
1263 | ||
7f80955e | 1264 | static void |
78d140c9 | 1265 | gcse_after_reload_main (rtx f ATTRIBUTE_UNUSED) |
1266 | { | |
5ee7391d | 1267 | |
78d140c9 | 1268 | memset (&stats, 0, sizeof (stats)); |
1269 | ||
f0b5f617 | 1270 | /* Allocate memory for this pass. |
78d140c9 | 1271 | Also computes and initializes the insns' CUIDs. */ |
1272 | alloc_mem (); | |
1273 | ||
1274 | /* We need alias analysis. */ | |
1275 | init_alias_analysis (); | |
1276 | ||
1277 | compute_hash_table (); | |
1278 | ||
1279 | if (dump_file) | |
1280 | dump_hash_table (dump_file); | |
1281 | ||
d9dd21a8 | 1282 | if (expr_table.elements () > 0) |
78d140c9 | 1283 | { |
1284 | eliminate_partially_redundant_loads (); | |
1285 | delete_redundant_insns (); | |
1286 | ||
1287 | if (dump_file) | |
1288 | { | |
1289 | fprintf (dump_file, "GCSE AFTER RELOAD stats:\n"); | |
1290 | fprintf (dump_file, "copies inserted: %d\n", stats.copies_inserted); | |
1291 | fprintf (dump_file, "moves inserted: %d\n", stats.moves_inserted); | |
1292 | fprintf (dump_file, "insns deleted: %d\n", stats.insns_deleted); | |
1293 | fprintf (dump_file, "\n\n"); | |
1294 | } | |
30c4e60d | 1295 | |
1296 | statistics_counter_event (cfun, "copies inserted", | |
1297 | stats.copies_inserted); | |
1298 | statistics_counter_event (cfun, "moves inserted", | |
1299 | stats.moves_inserted); | |
1300 | statistics_counter_event (cfun, "insns deleted", | |
1301 | stats.insns_deleted); | |
78d140c9 | 1302 | } |
48e1416a | 1303 | |
78d140c9 | 1304 | /* We are finished with alias. */ |
1305 | end_alias_analysis (); | |
1306 | ||
1307 | free_mem (); | |
1308 | } | |
1309 | ||
77fce4cd | 1310 | \f |
1311 | static bool | |
1312 | gate_handle_gcse2 (void) | |
1313 | { | |
7baffbd3 | 1314 | return (optimize > 0 && flag_gcse_after_reload |
1315 | && optimize_function_for_speed_p (cfun)); | |
77fce4cd | 1316 | } |
1317 | ||
1318 | ||
2a1990e9 | 1319 | static unsigned int |
77fce4cd | 1320 | rest_of_handle_gcse2 (void) |
1321 | { | |
1322 | gcse_after_reload_main (get_insns ()); | |
1323 | rebuild_jump_labels (get_insns ()); | |
2a1990e9 | 1324 | return 0; |
77fce4cd | 1325 | } |
1326 | ||
cbe8bda8 | 1327 | namespace { |
1328 | ||
1329 | const pass_data pass_data_gcse2 = | |
77fce4cd | 1330 | { |
cbe8bda8 | 1331 | RTL_PASS, /* type */ |
1332 | "gcse2", /* name */ | |
1333 | OPTGROUP_NONE, /* optinfo_flags */ | |
1334 | true, /* has_gate */ | |
1335 | true, /* has_execute */ | |
1336 | TV_GCSE_AFTER_RELOAD, /* tv_id */ | |
1337 | 0, /* properties_required */ | |
1338 | 0, /* properties_provided */ | |
1339 | 0, /* properties_destroyed */ | |
1340 | 0, /* todo_flags_start */ | |
1341 | ( TODO_verify_rtl_sharing | TODO_verify_flow ), /* todo_flags_finish */ | |
77fce4cd | 1342 | }; |
cbe8bda8 | 1343 | |
1344 | class pass_gcse2 : public rtl_opt_pass | |
1345 | { | |
1346 | public: | |
9af5ce0c | 1347 | pass_gcse2 (gcc::context *ctxt) |
1348 | : rtl_opt_pass (pass_data_gcse2, ctxt) | |
cbe8bda8 | 1349 | {} |
1350 | ||
1351 | /* opt_pass methods: */ | |
1352 | bool gate () { return gate_handle_gcse2 (); } | |
1353 | unsigned int execute () { return rest_of_handle_gcse2 (); } | |
1354 | ||
1355 | }; // class pass_gcse2 | |
1356 | ||
1357 | } // anon namespace | |
1358 | ||
1359 | rtl_opt_pass * | |
1360 | make_pass_gcse2 (gcc::context *ctxt) | |
1361 | { | |
1362 | return new pass_gcse2 (ctxt); | |
1363 | } |