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78d140c9 | 1 | /* Post reload partially redundant load elimination |
f1717362 | 2 | Copyright (C) 2004-2016 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" | |
9ef16211 | 23 | #include "backend.h" |
7c29e30e | 24 | #include "target.h" |
9ef16211 | 25 | #include "rtl.h" |
7c29e30e | 26 | #include "tree.h" |
27 | #include "predict.h" | |
9ef16211 | 28 | #include "df.h" |
7c29e30e | 29 | #include "tm_p.h" |
7c29e30e | 30 | #include "insn-config.h" |
7c29e30e | 31 | #include "emit-rtl.h" |
32 | #include "recog.h" | |
78d140c9 | 33 | |
94ea8568 | 34 | #include "cfgrtl.h" |
886c1262 | 35 | #include "profile.h" |
78d140c9 | 36 | #include "expr.h" |
78d140c9 | 37 | #include "params.h" |
77fce4cd | 38 | #include "tree-pass.h" |
3072d30e | 39 | #include "dbgcnt.h" |
d2ac64b1 | 40 | #include "gcse-common.h" |
78d140c9 | 41 | |
42 | /* The following code implements gcse after reload, the purpose of this | |
43 | pass is to cleanup redundant loads generated by reload and other | |
44 | optimizations that come after gcse. It searches for simple inter-block | |
45 | redundancies and tries to eliminate them by adding moves and loads | |
46 | in cold places. | |
47 | ||
48 | Perform partially redundant load elimination, try to eliminate redundant | |
49 | loads created by the reload pass. We try to look for full or partial | |
50 | redundant loads fed by one or more loads/stores in predecessor BBs, | |
51 | and try adding loads to make them fully redundant. We also check if | |
52 | it's worth adding loads to be able to delete the redundant load. | |
53 | ||
54 | Algorithm: | |
55 | 1. Build available expressions hash table: | |
56 | For each load/store instruction, if the loaded/stored memory didn't | |
57 | change until the end of the basic block add this memory expression to | |
58 | the hash table. | |
59 | 2. Perform Redundancy elimination: | |
60 | For each load instruction do the following: | |
61 | perform partial redundancy elimination, check if it's worth adding | |
62 | loads to make the load fully redundant. If so add loads and | |
63 | register copies and delete the load. | |
64 | 3. Delete instructions made redundant in step 2. | |
65 | ||
66 | Future enhancement: | |
67 | If the loaded register is used/defined between load and some store, | |
68 | look for some other free register between load and all its stores, | |
69 | and replace the load with a copy from this register to the loaded | |
70 | register. | |
71 | */ | |
72 | \f | |
73 | ||
74 | /* Keep statistics of this pass. */ | |
75 | static struct | |
76 | { | |
77 | int moves_inserted; | |
78 | int copies_inserted; | |
79 | int insns_deleted; | |
80 | } stats; | |
81 | ||
82 | /* We need to keep a hash table of expressions. The table entries are of | |
83 | type 'struct expr', and for each expression there is a single linked | |
91275768 | 84 | list of occurrences. */ |
78d140c9 | 85 | |
78d140c9 | 86 | /* Expression elements in the hash table. */ |
87 | struct expr | |
88 | { | |
89 | /* The expression (SET_SRC for expressions, PATTERN for assignments). */ | |
90 | rtx expr; | |
91 | ||
92 | /* The same hash for this entry. */ | |
93 | hashval_t hash; | |
94 | ||
d2ac64b1 | 95 | /* Index in the transparent bitmaps. */ |
96 | unsigned int bitmap_index; | |
97 | ||
78d140c9 | 98 | /* List of available occurrence in basic blocks in the function. */ |
99 | struct occr *avail_occr; | |
100 | }; | |
101 | ||
d9dd21a8 | 102 | /* Hashtable helpers. */ |
103 | ||
770ff93b | 104 | struct expr_hasher : nofree_ptr_hash <expr> |
d9dd21a8 | 105 | { |
9969c043 | 106 | static inline hashval_t hash (const expr *); |
107 | static inline bool equal (const expr *, const expr *); | |
d9dd21a8 | 108 | }; |
109 | ||
110 | ||
111 | /* Hash expression X. | |
112 | DO_NOT_RECORD_P is a boolean indicating if a volatile operand is found | |
113 | or if the expression contains something we don't want to insert in the | |
114 | table. */ | |
115 | ||
116 | static hashval_t | |
117 | hash_expr (rtx x, int *do_not_record_p) | |
118 | { | |
119 | *do_not_record_p = 0; | |
120 | return hash_rtx (x, GET_MODE (x), do_not_record_p, | |
121 | NULL, /*have_reg_qty=*/false); | |
122 | } | |
123 | ||
124 | /* Callback for hashtab. | |
125 | Return the hash value for expression EXP. We don't actually hash | |
126 | here, we just return the cached hash value. */ | |
127 | ||
128 | inline hashval_t | |
9969c043 | 129 | expr_hasher::hash (const expr *exp) |
d9dd21a8 | 130 | { |
131 | return exp->hash; | |
132 | } | |
133 | ||
134 | /* Callback for hashtab. | |
135 | Return nonzero if exp1 is equivalent to exp2. */ | |
136 | ||
137 | inline bool | |
9969c043 | 138 | expr_hasher::equal (const expr *exp1, const expr *exp2) |
d9dd21a8 | 139 | { |
140 | int equiv_p = exp_equiv_p (exp1->expr, exp2->expr, 0, true); | |
141 | ||
142 | gcc_assert (!equiv_p || exp1->hash == exp2->hash); | |
143 | return equiv_p; | |
144 | } | |
145 | ||
146 | /* The table itself. */ | |
c1f445d2 | 147 | static hash_table<expr_hasher> *expr_table; |
d9dd21a8 | 148 | \f |
149 | ||
78d140c9 | 150 | static struct obstack expr_obstack; |
151 | ||
152 | /* Occurrence of an expression. | |
91275768 | 153 | There is at most one occurrence per basic block. If a pattern appears |
78d140c9 | 154 | more than once, the last appearance is used. */ |
155 | ||
156 | struct occr | |
157 | { | |
158 | /* Next occurrence of this expression. */ | |
159 | struct occr *next; | |
160 | /* The insn that computes the expression. */ | |
cdace3a0 | 161 | rtx_insn *insn; |
78d140c9 | 162 | /* Nonzero if this [anticipatable] occurrence has been deleted. */ |
163 | char deleted_p; | |
164 | }; | |
165 | ||
166 | static struct obstack occr_obstack; | |
167 | ||
168 | /* The following structure holds the information about the occurrences of | |
169 | the redundant instructions. */ | |
170 | struct unoccr | |
171 | { | |
172 | struct unoccr *next; | |
173 | edge pred; | |
cdace3a0 | 174 | rtx_insn *insn; |
78d140c9 | 175 | }; |
176 | ||
177 | static struct obstack unoccr_obstack; | |
178 | ||
179 | /* Array where each element is the CUID if the insn that last set the hard | |
180 | register with the number of the element, since the start of the current | |
d447762f | 181 | basic block. |
182 | ||
183 | This array is used during the building of the hash table (step 1) to | |
184 | determine if a reg is killed before the end of a basic block. | |
185 | ||
186 | It is also used when eliminating partial redundancies (step 2) to see | |
187 | if a reg was modified since the start of a basic block. */ | |
78d140c9 | 188 | static int *reg_avail_info; |
189 | ||
190 | /* A list of insns that may modify memory within the current basic block. */ | |
191 | struct modifies_mem | |
192 | { | |
cdace3a0 | 193 | rtx_insn *insn; |
78d140c9 | 194 | struct modifies_mem *next; |
195 | }; | |
196 | static struct modifies_mem *modifies_mem_list; | |
197 | ||
198 | /* The modifies_mem structs also go on an obstack, only this obstack is | |
199 | freed each time after completing the analysis or transformations on | |
200 | a basic block. So we allocate a dummy modifies_mem_obstack_bottom | |
201 | object on the obstack to keep track of the bottom of the obstack. */ | |
202 | static struct obstack modifies_mem_obstack; | |
203 | static struct modifies_mem *modifies_mem_obstack_bottom; | |
204 | ||
205 | /* Mapping of insn UIDs to CUIDs. | |
206 | CUIDs are like UIDs except they increase monotonically in each basic | |
207 | block, have no gaps, and only apply to real insns. */ | |
208 | static int *uid_cuid; | |
209 | #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)]) | |
d2ac64b1 | 210 | |
211 | /* Bitmap of blocks which have memory stores. */ | |
212 | static bitmap modify_mem_list_set; | |
213 | ||
214 | /* Bitmap of blocks which have calls. */ | |
215 | static bitmap blocks_with_calls; | |
216 | ||
217 | /* Vector indexed by block # with a list of all the insns that | |
218 | modify memory within the block. */ | |
219 | static vec<rtx_insn *> *modify_mem_list; | |
220 | ||
221 | /* Vector indexed by block # with a canonicalized list of insns | |
222 | that modify memory in the block. */ | |
223 | static vec<modify_pair> *canon_modify_mem_list; | |
224 | ||
225 | /* Vector of simple bitmaps indexed by block number. Each component sbitmap | |
226 | indicates which expressions are transparent through the block. */ | |
227 | static sbitmap *transp; | |
78d140c9 | 228 | \f |
229 | ||
230 | /* Helpers for memory allocation/freeing. */ | |
231 | static void alloc_mem (void); | |
232 | static void free_mem (void); | |
233 | ||
234 | /* Support for hash table construction and transformations. */ | |
cdace3a0 | 235 | static bool oprs_unchanged_p (rtx, rtx_insn *, bool); |
236 | static void record_last_reg_set_info (rtx_insn *, rtx); | |
237 | static void record_last_reg_set_info_regno (rtx_insn *, int); | |
238 | static void record_last_mem_set_info (rtx_insn *); | |
81a410b1 | 239 | static void record_last_set_info (rtx, const_rtx, void *); |
cdace3a0 | 240 | static void record_opr_changes (rtx_insn *); |
78d140c9 | 241 | |
81a410b1 | 242 | static void find_mem_conflicts (rtx, const_rtx, void *); |
78d140c9 | 243 | static int load_killed_in_block_p (int, rtx, bool); |
244 | static void reset_opr_set_tables (void); | |
245 | ||
246 | /* Hash table support. */ | |
247 | static hashval_t hash_expr (rtx, int *); | |
cdace3a0 | 248 | static void insert_expr_in_table (rtx, rtx_insn *); |
78d140c9 | 249 | static struct expr *lookup_expr_in_table (rtx); |
78d140c9 | 250 | static void dump_hash_table (FILE *); |
251 | ||
252 | /* Helpers for eliminate_partially_redundant_load. */ | |
253 | static bool reg_killed_on_edge (rtx, edge); | |
254 | static bool reg_used_on_edge (rtx, edge); | |
255 | ||
cdace3a0 | 256 | static rtx get_avail_load_store_reg (rtx_insn *); |
78d140c9 | 257 | |
258 | static bool bb_has_well_behaved_predecessors (basic_block); | |
d2ac64b1 | 259 | static struct occr* get_bb_avail_insn (basic_block, struct occr *, int); |
cdace3a0 | 260 | static void hash_scan_set (rtx_insn *); |
78d140c9 | 261 | static void compute_hash_table (void); |
262 | ||
263 | /* The work horses of this pass. */ | |
264 | static void eliminate_partially_redundant_load (basic_block, | |
cdace3a0 | 265 | rtx_insn *, |
78d140c9 | 266 | struct expr *); |
267 | static void eliminate_partially_redundant_loads (void); | |
268 | \f | |
269 | ||
270 | /* Allocate memory for the CUID mapping array and register/memory | |
271 | tracking tables. */ | |
272 | ||
273 | static void | |
274 | alloc_mem (void) | |
275 | { | |
276 | int i; | |
277 | basic_block bb; | |
cdace3a0 | 278 | rtx_insn *insn; |
78d140c9 | 279 | |
280 | /* Find the largest UID and create a mapping from UIDs to CUIDs. */ | |
4c36ffe6 | 281 | uid_cuid = XCNEWVEC (int, get_max_uid () + 1); |
1539153f | 282 | i = 1; |
fc00614f | 283 | FOR_EACH_BB_FN (bb, cfun) |
78d140c9 | 284 | FOR_BB_INSNS (bb, insn) |
285 | { | |
286 | if (INSN_P (insn)) | |
287 | uid_cuid[INSN_UID (insn)] = i++; | |
288 | else | |
289 | uid_cuid[INSN_UID (insn)] = i; | |
290 | } | |
291 | ||
292 | /* Allocate the available expressions hash table. We don't want to | |
293 | make the hash table too small, but unnecessarily making it too large | |
294 | also doesn't help. The i/4 is a gcse.c relic, and seems like a | |
295 | reasonable choice. */ | |
c1f445d2 | 296 | expr_table = new hash_table<expr_hasher> (MAX (i / 4, 13)); |
78d140c9 | 297 | |
298 | /* We allocate everything on obstacks because we often can roll back | |
299 | the whole obstack to some point. Freeing obstacks is very fast. */ | |
300 | gcc_obstack_init (&expr_obstack); | |
301 | gcc_obstack_init (&occr_obstack); | |
302 | gcc_obstack_init (&unoccr_obstack); | |
303 | gcc_obstack_init (&modifies_mem_obstack); | |
304 | ||
305 | /* Working array used to track the last set for each register | |
306 | in the current block. */ | |
307 | reg_avail_info = (int *) xmalloc (FIRST_PSEUDO_REGISTER * sizeof (int)); | |
308 | ||
309 | /* Put a dummy modifies_mem object on the modifies_mem_obstack, so we | |
310 | can roll it back in reset_opr_set_tables. */ | |
311 | modifies_mem_obstack_bottom = | |
312 | (struct modifies_mem *) obstack_alloc (&modifies_mem_obstack, | |
313 | sizeof (struct modifies_mem)); | |
d2ac64b1 | 314 | |
315 | blocks_with_calls = BITMAP_ALLOC (NULL); | |
316 | modify_mem_list_set = BITMAP_ALLOC (NULL); | |
317 | ||
318 | modify_mem_list = (vec_rtx_heap *) xcalloc (last_basic_block_for_fn (cfun), | |
319 | sizeof (vec_rtx_heap)); | |
320 | canon_modify_mem_list | |
321 | = (vec_modify_pair_heap *) xcalloc (last_basic_block_for_fn (cfun), | |
322 | sizeof (vec_modify_pair_heap)); | |
78d140c9 | 323 | } |
324 | ||
325 | /* Free memory allocated by alloc_mem. */ | |
326 | ||
327 | static void | |
328 | free_mem (void) | |
329 | { | |
330 | free (uid_cuid); | |
331 | ||
c1f445d2 | 332 | delete expr_table; |
333 | expr_table = NULL; | |
78d140c9 | 334 | |
335 | obstack_free (&expr_obstack, NULL); | |
336 | obstack_free (&occr_obstack, NULL); | |
337 | obstack_free (&unoccr_obstack, NULL); | |
338 | obstack_free (&modifies_mem_obstack, NULL); | |
339 | ||
d2ac64b1 | 340 | unsigned i; |
341 | bitmap_iterator bi; | |
342 | EXECUTE_IF_SET_IN_BITMAP (modify_mem_list_set, 0, i, bi) | |
343 | { | |
344 | modify_mem_list[i].release (); | |
345 | canon_modify_mem_list[i].release (); | |
346 | } | |
347 | ||
348 | BITMAP_FREE (blocks_with_calls); | |
349 | BITMAP_FREE (modify_mem_list_set); | |
78d140c9 | 350 | free (reg_avail_info); |
c45ca67d | 351 | free (modify_mem_list); |
352 | free (canon_modify_mem_list); | |
78d140c9 | 353 | } |
354 | \f | |
355 | ||
78d140c9 | 356 | /* Insert expression X in INSN in the hash TABLE. |
357 | If it is already present, record it as the last occurrence in INSN's | |
358 | basic block. */ | |
359 | ||
360 | static void | |
cdace3a0 | 361 | insert_expr_in_table (rtx x, rtx_insn *insn) |
78d140c9 | 362 | { |
363 | int do_not_record_p; | |
364 | hashval_t hash; | |
365 | struct expr *cur_expr, **slot; | |
366 | struct occr *avail_occr, *last_occr = NULL; | |
367 | ||
368 | hash = hash_expr (x, &do_not_record_p); | |
369 | ||
370 | /* Do not insert expression in the table if it contains volatile operands, | |
371 | or if hash_expr determines the expression is something we don't want | |
372 | to or can't handle. */ | |
373 | if (do_not_record_p) | |
374 | return; | |
375 | ||
376 | /* We anticipate that redundant expressions are rare, so for convenience | |
377 | allocate a new hash table element here already and set its fields. | |
378 | If we don't do this, we need a hack with a static struct expr. Anyway, | |
379 | obstack_free is really fast and one more obstack_alloc doesn't hurt if | |
380 | we're going to see more expressions later on. */ | |
381 | cur_expr = (struct expr *) obstack_alloc (&expr_obstack, | |
382 | sizeof (struct expr)); | |
383 | cur_expr->expr = x; | |
384 | cur_expr->hash = hash; | |
385 | cur_expr->avail_occr = NULL; | |
386 | ||
c1f445d2 | 387 | slot = expr_table->find_slot_with_hash (cur_expr, hash, INSERT); |
48e1416a | 388 | |
78d140c9 | 389 | if (! (*slot)) |
d2ac64b1 | 390 | { |
391 | /* The expression isn't found, so insert it. */ | |
392 | *slot = cur_expr; | |
393 | ||
394 | /* Anytime we add an entry to the table, record the index | |
395 | of the new entry. The bitmap index starts counting | |
396 | at zero. */ | |
397 | cur_expr->bitmap_index = expr_table->elements () - 1; | |
398 | } | |
78d140c9 | 399 | else |
400 | { | |
401 | /* The expression is already in the table, so roll back the | |
402 | obstack and use the existing table entry. */ | |
403 | obstack_free (&expr_obstack, cur_expr); | |
404 | cur_expr = *slot; | |
405 | } | |
406 | ||
407 | /* Search for another occurrence in the same basic block. */ | |
408 | avail_occr = cur_expr->avail_occr; | |
90bd219d | 409 | while (avail_occr |
410 | && BLOCK_FOR_INSN (avail_occr->insn) != BLOCK_FOR_INSN (insn)) | |
78d140c9 | 411 | { |
412 | /* If an occurrence isn't found, save a pointer to the end of | |
413 | the list. */ | |
414 | last_occr = avail_occr; | |
415 | avail_occr = avail_occr->next; | |
416 | } | |
417 | ||
418 | if (avail_occr) | |
419 | /* Found another instance of the expression in the same basic block. | |
420 | Prefer this occurrence to the currently recorded one. We want | |
421 | the last one in the block and the block is scanned from start | |
422 | to end. */ | |
423 | avail_occr->insn = insn; | |
424 | else | |
425 | { | |
426 | /* First occurrence of this expression in this basic block. */ | |
427 | avail_occr = (struct occr *) obstack_alloc (&occr_obstack, | |
428 | sizeof (struct occr)); | |
429 | ||
430 | /* First occurrence of this expression in any block? */ | |
431 | if (cur_expr->avail_occr == NULL) | |
432 | cur_expr->avail_occr = avail_occr; | |
433 | else | |
434 | last_occr->next = avail_occr; | |
435 | ||
436 | avail_occr->insn = insn; | |
437 | avail_occr->next = NULL; | |
438 | avail_occr->deleted_p = 0; | |
439 | } | |
440 | } | |
441 | \f | |
442 | ||
443 | /* Lookup pattern PAT in the expression hash table. | |
444 | The result is a pointer to the table entry, or NULL if not found. */ | |
445 | ||
446 | static struct expr * | |
447 | lookup_expr_in_table (rtx pat) | |
448 | { | |
449 | int do_not_record_p; | |
450 | struct expr **slot, *tmp_expr; | |
451 | hashval_t hash = hash_expr (pat, &do_not_record_p); | |
452 | ||
453 | if (do_not_record_p) | |
454 | return NULL; | |
455 | ||
456 | tmp_expr = (struct expr *) obstack_alloc (&expr_obstack, | |
457 | sizeof (struct expr)); | |
458 | tmp_expr->expr = pat; | |
459 | tmp_expr->hash = hash; | |
460 | tmp_expr->avail_occr = NULL; | |
461 | ||
c1f445d2 | 462 | slot = expr_table->find_slot_with_hash (tmp_expr, hash, INSERT); |
78d140c9 | 463 | obstack_free (&expr_obstack, tmp_expr); |
464 | ||
465 | if (!slot) | |
466 | return NULL; | |
467 | else | |
468 | return (*slot); | |
469 | } | |
470 | \f | |
471 | ||
91275768 | 472 | /* Dump all expressions and occurrences that are currently in the |
78d140c9 | 473 | expression hash table to FILE. */ |
474 | ||
475 | /* This helper is called via htab_traverse. */ | |
d9dd21a8 | 476 | int |
477 | dump_expr_hash_table_entry (expr **slot, FILE *file) | |
78d140c9 | 478 | { |
d9dd21a8 | 479 | struct expr *exprs = *slot; |
78d140c9 | 480 | struct occr *occr; |
481 | ||
482 | fprintf (file, "expr: "); | |
d9dd21a8 | 483 | print_rtl (file, exprs->expr); |
484 | fprintf (file,"\nhashcode: %u\n", exprs->hash); | |
4133d091 | 485 | fprintf (file,"list of occurrences:\n"); |
d9dd21a8 | 486 | occr = exprs->avail_occr; |
78d140c9 | 487 | while (occr) |
488 | { | |
cdace3a0 | 489 | rtx_insn *insn = occr->insn; |
78d140c9 | 490 | print_rtl_single (file, insn); |
491 | fprintf (file, "\n"); | |
492 | occr = occr->next; | |
493 | } | |
494 | fprintf (file, "\n"); | |
495 | return 1; | |
496 | } | |
497 | ||
498 | static void | |
499 | dump_hash_table (FILE *file) | |
500 | { | |
501 | fprintf (file, "\n\nexpression hash table\n"); | |
502 | fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n", | |
c1f445d2 | 503 | (long) expr_table->size (), |
504 | (long) expr_table->elements (), | |
505 | expr_table->collisions ()); | |
506 | if (expr_table->elements () > 0) | |
78d140c9 | 507 | { |
508 | fprintf (file, "\n\ntable entries:\n"); | |
c1f445d2 | 509 | expr_table->traverse <FILE *, dump_expr_hash_table_entry> (file); |
78d140c9 | 510 | } |
511 | fprintf (file, "\n"); | |
512 | } | |
513 | \f | |
20128b13 | 514 | /* Return true if register X is recorded as being set by an instruction |
515 | whose CUID is greater than the one given. */ | |
516 | ||
517 | static bool | |
518 | reg_changed_after_insn_p (rtx x, int cuid) | |
519 | { | |
520 | unsigned int regno, end_regno; | |
521 | ||
522 | regno = REGNO (x); | |
788bed51 | 523 | end_regno = END_REGNO (x); |
20128b13 | 524 | do |
525 | if (reg_avail_info[regno] > cuid) | |
526 | return true; | |
527 | while (++regno < end_regno); | |
528 | return false; | |
529 | } | |
78d140c9 | 530 | |
d447762f | 531 | /* Return nonzero if the operands of expression X are unchanged |
532 | 1) from the start of INSN's basic block up to but not including INSN | |
533 | if AFTER_INSN is false, or | |
534 | 2) from INSN to the end of INSN's basic block if AFTER_INSN is true. */ | |
78d140c9 | 535 | |
536 | static bool | |
cdace3a0 | 537 | oprs_unchanged_p (rtx x, rtx_insn *insn, bool after_insn) |
78d140c9 | 538 | { |
539 | int i, j; | |
540 | enum rtx_code code; | |
541 | const char *fmt; | |
542 | ||
543 | if (x == 0) | |
544 | return 1; | |
545 | ||
546 | code = GET_CODE (x); | |
547 | switch (code) | |
548 | { | |
549 | case REG: | |
78d140c9 | 550 | /* We are called after register allocation. */ |
876760f6 | 551 | gcc_assert (REGNO (x) < FIRST_PSEUDO_REGISTER); |
78d140c9 | 552 | if (after_insn) |
20128b13 | 553 | return !reg_changed_after_insn_p (x, INSN_CUID (insn) - 1); |
78d140c9 | 554 | else |
20128b13 | 555 | return !reg_changed_after_insn_p (x, 0); |
78d140c9 | 556 | |
557 | case MEM: | |
558 | if (load_killed_in_block_p (INSN_CUID (insn), x, after_insn)) | |
559 | return 0; | |
560 | else | |
561 | return oprs_unchanged_p (XEXP (x, 0), insn, after_insn); | |
562 | ||
563 | case PC: | |
564 | case CC0: /*FIXME*/ | |
565 | case CONST: | |
0349edce | 566 | CASE_CONST_ANY: |
78d140c9 | 567 | case SYMBOL_REF: |
568 | case LABEL_REF: | |
569 | case ADDR_VEC: | |
570 | case ADDR_DIFF_VEC: | |
571 | return 1; | |
572 | ||
573 | case PRE_DEC: | |
574 | case PRE_INC: | |
575 | case POST_DEC: | |
576 | case POST_INC: | |
577 | case PRE_MODIFY: | |
578 | case POST_MODIFY: | |
579 | if (after_insn) | |
580 | return 0; | |
581 | break; | |
582 | ||
583 | default: | |
584 | break; | |
585 | } | |
586 | ||
587 | for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--) | |
588 | { | |
589 | if (fmt[i] == 'e') | |
590 | { | |
591 | if (! oprs_unchanged_p (XEXP (x, i), insn, after_insn)) | |
592 | return 0; | |
593 | } | |
594 | else if (fmt[i] == 'E') | |
595 | for (j = 0; j < XVECLEN (x, i); j++) | |
596 | if (! oprs_unchanged_p (XVECEXP (x, i, j), insn, after_insn)) | |
597 | return 0; | |
598 | } | |
599 | ||
600 | return 1; | |
601 | } | |
602 | \f | |
603 | ||
604 | /* Used for communication between find_mem_conflicts and | |
605 | load_killed_in_block_p. Nonzero if find_mem_conflicts finds a | |
606 | conflict between two memory references. | |
607 | This is a bit of a hack to work around the limitations of note_stores. */ | |
608 | static int mems_conflict_p; | |
609 | ||
610 | /* DEST is the output of an instruction. If it is a memory reference, and | |
611 | possibly conflicts with the load found in DATA, then set mems_conflict_p | |
612 | to a nonzero value. */ | |
613 | ||
614 | static void | |
81a410b1 | 615 | find_mem_conflicts (rtx dest, const_rtx setter ATTRIBUTE_UNUSED, |
78d140c9 | 616 | void *data) |
617 | { | |
618 | rtx mem_op = (rtx) data; | |
619 | ||
620 | while (GET_CODE (dest) == SUBREG | |
621 | || GET_CODE (dest) == ZERO_EXTRACT | |
78d140c9 | 622 | || GET_CODE (dest) == STRICT_LOW_PART) |
623 | dest = XEXP (dest, 0); | |
624 | ||
625 | /* If DEST is not a MEM, then it will not conflict with the load. Note | |
626 | that function calls are assumed to clobber memory, but are handled | |
627 | elsewhere. */ | |
628 | if (! MEM_P (dest)) | |
629 | return; | |
630 | ||
376a287d | 631 | if (true_dependence (dest, GET_MODE (dest), mem_op)) |
78d140c9 | 632 | mems_conflict_p = 1; |
633 | } | |
634 | \f | |
635 | ||
636 | /* Return nonzero if the expression in X (a memory reference) is killed | |
d447762f | 637 | in the current basic block before (if AFTER_INSN is false) or after |
638 | (if AFTER_INSN is true) the insn with the CUID in UID_LIMIT. | |
639 | ||
640 | This function assumes that the modifies_mem table is flushed when | |
641 | the hash table construction or redundancy elimination phases start | |
642 | processing a new basic block. */ | |
78d140c9 | 643 | |
644 | static int | |
645 | load_killed_in_block_p (int uid_limit, rtx x, bool after_insn) | |
646 | { | |
647 | struct modifies_mem *list_entry = modifies_mem_list; | |
648 | ||
649 | while (list_entry) | |
650 | { | |
cdace3a0 | 651 | rtx_insn *setter = list_entry->insn; |
78d140c9 | 652 | |
653 | /* Ignore entries in the list that do not apply. */ | |
654 | if ((after_insn | |
655 | && INSN_CUID (setter) < uid_limit) | |
656 | || (! after_insn | |
657 | && INSN_CUID (setter) > uid_limit)) | |
658 | { | |
659 | list_entry = list_entry->next; | |
660 | continue; | |
661 | } | |
662 | ||
663 | /* If SETTER is a call everything is clobbered. Note that calls | |
664 | to pure functions are never put on the list, so we need not | |
665 | worry about them. */ | |
666 | if (CALL_P (setter)) | |
667 | return 1; | |
668 | ||
669 | /* SETTER must be an insn of some kind that sets memory. Call | |
670 | note_stores to examine each hunk of memory that is modified. | |
671 | It will set mems_conflict_p to nonzero if there may be a | |
672 | conflict between X and SETTER. */ | |
673 | mems_conflict_p = 0; | |
674 | note_stores (PATTERN (setter), find_mem_conflicts, x); | |
675 | if (mems_conflict_p) | |
676 | return 1; | |
677 | ||
678 | list_entry = list_entry->next; | |
679 | } | |
680 | return 0; | |
681 | } | |
682 | \f | |
683 | ||
684 | /* Record register first/last/block set information for REGNO in INSN. */ | |
685 | ||
d447762f | 686 | static inline void |
cdace3a0 | 687 | record_last_reg_set_info (rtx_insn *insn, rtx reg) |
ce53880e | 688 | { |
689 | unsigned int regno, end_regno; | |
690 | ||
691 | regno = REGNO (reg); | |
788bed51 | 692 | end_regno = END_REGNO (reg); |
ce53880e | 693 | do |
694 | reg_avail_info[regno] = INSN_CUID (insn); | |
695 | while (++regno < end_regno); | |
696 | } | |
697 | ||
698 | static inline void | |
cdace3a0 | 699 | record_last_reg_set_info_regno (rtx_insn *insn, int regno) |
78d140c9 | 700 | { |
701 | reg_avail_info[regno] = INSN_CUID (insn); | |
702 | } | |
703 | ||
704 | ||
705 | /* Record memory modification information for INSN. We do not actually care | |
706 | about the memory location(s) that are set, or even how they are set (consider | |
707 | a CALL_INSN). We merely need to record which insns modify memory. */ | |
708 | ||
709 | static void | |
cdace3a0 | 710 | record_last_mem_set_info (rtx_insn *insn) |
78d140c9 | 711 | { |
712 | struct modifies_mem *list_entry; | |
713 | ||
714 | list_entry = (struct modifies_mem *) obstack_alloc (&modifies_mem_obstack, | |
715 | sizeof (struct modifies_mem)); | |
716 | list_entry->insn = insn; | |
717 | list_entry->next = modifies_mem_list; | |
718 | modifies_mem_list = list_entry; | |
d2ac64b1 | 719 | |
720 | record_last_mem_set_info_common (insn, modify_mem_list, | |
721 | canon_modify_mem_list, | |
722 | modify_mem_list_set, | |
723 | blocks_with_calls); | |
78d140c9 | 724 | } |
725 | ||
726 | /* Called from compute_hash_table via note_stores to handle one | |
727 | SET or CLOBBER in an insn. DATA is really the instruction in which | |
728 | the SET is taking place. */ | |
729 | ||
730 | static void | |
81a410b1 | 731 | record_last_set_info (rtx dest, const_rtx setter ATTRIBUTE_UNUSED, void *data) |
78d140c9 | 732 | { |
cdace3a0 | 733 | rtx_insn *last_set_insn = (rtx_insn *) data; |
78d140c9 | 734 | |
735 | if (GET_CODE (dest) == SUBREG) | |
736 | dest = SUBREG_REG (dest); | |
737 | ||
738 | if (REG_P (dest)) | |
ce53880e | 739 | record_last_reg_set_info (last_set_insn, dest); |
5630a23e | 740 | else if (MEM_P (dest)) |
741 | { | |
742 | /* Ignore pushes, they don't clobber memory. They may still | |
743 | clobber the stack pointer though. Some targets do argument | |
744 | pushes without adding REG_INC notes. See e.g. PR25196, | |
745 | where a pushsi2 on i386 doesn't have REG_INC notes. Note | |
746 | such changes here too. */ | |
747 | if (! push_operand (dest, GET_MODE (dest))) | |
748 | record_last_mem_set_info (last_set_insn); | |
749 | else | |
ce53880e | 750 | record_last_reg_set_info_regno (last_set_insn, STACK_POINTER_REGNUM); |
5630a23e | 751 | } |
78d140c9 | 752 | } |
d447762f | 753 | |
78d140c9 | 754 | |
755 | /* Reset tables used to keep track of what's still available since the | |
756 | start of the block. */ | |
757 | ||
758 | static void | |
759 | reset_opr_set_tables (void) | |
760 | { | |
761 | memset (reg_avail_info, 0, FIRST_PSEUDO_REGISTER * sizeof (int)); | |
762 | obstack_free (&modifies_mem_obstack, modifies_mem_obstack_bottom); | |
763 | modifies_mem_list = NULL; | |
764 | } | |
d447762f | 765 | \f |
78d140c9 | 766 | |
767 | /* Record things set by INSN. | |
768 | This data is used by oprs_unchanged_p. */ | |
769 | ||
770 | static void | |
cdace3a0 | 771 | record_opr_changes (rtx_insn *insn) |
78d140c9 | 772 | { |
d447762f | 773 | rtx note; |
78d140c9 | 774 | |
d447762f | 775 | /* Find all stores and record them. */ |
776 | note_stores (PATTERN (insn), record_last_set_info, insn); | |
78d140c9 | 777 | |
d447762f | 778 | /* Also record autoincremented REGs for this insn as changed. */ |
779 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) | |
780 | if (REG_NOTE_KIND (note) == REG_INC) | |
ce53880e | 781 | record_last_reg_set_info (insn, XEXP (note, 0)); |
78d140c9 | 782 | |
d447762f | 783 | /* Finally, if this is a call, record all call clobbers. */ |
784 | if (CALL_P (insn)) | |
785 | { | |
ce53880e | 786 | unsigned int regno; |
20128b13 | 787 | rtx link, x; |
24ec6636 | 788 | hard_reg_set_iterator hrsi; |
789 | EXECUTE_IF_SET_IN_HARD_REG_SET (regs_invalidated_by_call, 0, regno, hrsi) | |
790 | record_last_reg_set_info_regno (insn, regno); | |
78d140c9 | 791 | |
20128b13 | 792 | for (link = CALL_INSN_FUNCTION_USAGE (insn); link; link = XEXP (link, 1)) |
793 | if (GET_CODE (XEXP (link, 0)) == CLOBBER) | |
794 | { | |
795 | x = XEXP (XEXP (link, 0), 0); | |
796 | if (REG_P (x)) | |
797 | { | |
798 | gcc_assert (HARD_REGISTER_P (x)); | |
ce53880e | 799 | record_last_reg_set_info (insn, x); |
20128b13 | 800 | } |
801 | } | |
802 | ||
9c2a0c05 | 803 | if (! RTL_CONST_OR_PURE_CALL_P (insn)) |
d447762f | 804 | record_last_mem_set_info (insn); |
805 | } | |
78d140c9 | 806 | } |
807 | \f | |
808 | ||
809 | /* Scan the pattern of INSN and add an entry to the hash TABLE. | |
810 | After reload we are interested in loads/stores only. */ | |
811 | ||
812 | static void | |
cdace3a0 | 813 | hash_scan_set (rtx_insn *insn) |
78d140c9 | 814 | { |
815 | rtx pat = PATTERN (insn); | |
816 | rtx src = SET_SRC (pat); | |
817 | rtx dest = SET_DEST (pat); | |
818 | ||
819 | /* We are only interested in loads and stores. */ | |
820 | if (! MEM_P (src) && ! MEM_P (dest)) | |
821 | return; | |
822 | ||
823 | /* Don't mess with jumps and nops. */ | |
824 | if (JUMP_P (insn) || set_noop_p (pat)) | |
825 | return; | |
826 | ||
78d140c9 | 827 | if (REG_P (dest)) |
828 | { | |
d447762f | 829 | if (/* Don't CSE something if we can't do a reg/reg copy. */ |
78d140c9 | 830 | can_copy_p (GET_MODE (dest)) |
831 | /* Is SET_SRC something we want to gcse? */ | |
832 | && general_operand (src, GET_MODE (src)) | |
868e8f12 | 833 | #ifdef STACK_REGS |
834 | /* Never consider insns touching the register stack. It may | |
835 | create situations that reg-stack cannot handle (e.g. a stack | |
836 | register live across an abnormal edge). */ | |
837 | && (REGNO (dest) < FIRST_STACK_REG || REGNO (dest) > LAST_STACK_REG) | |
838 | #endif | |
78d140c9 | 839 | /* An expression is not available if its operands are |
840 | subsequently modified, including this insn. */ | |
841 | && oprs_unchanged_p (src, insn, true)) | |
842 | { | |
843 | insert_expr_in_table (src, insn); | |
844 | } | |
845 | } | |
846 | else if (REG_P (src)) | |
847 | { | |
848 | /* Only record sets of pseudo-regs in the hash table. */ | |
d447762f | 849 | if (/* Don't CSE something if we can't do a reg/reg copy. */ |
78d140c9 | 850 | can_copy_p (GET_MODE (src)) |
851 | /* Is SET_DEST something we want to gcse? */ | |
852 | && general_operand (dest, GET_MODE (dest)) | |
868e8f12 | 853 | #ifdef STACK_REGS |
854 | /* As above for STACK_REGS. */ | |
855 | && (REGNO (src) < FIRST_STACK_REG || REGNO (src) > LAST_STACK_REG) | |
856 | #endif | |
78d140c9 | 857 | && ! (flag_float_store && FLOAT_MODE_P (GET_MODE (dest))) |
858 | /* Check if the memory expression is killed after insn. */ | |
859 | && ! load_killed_in_block_p (INSN_CUID (insn) + 1, dest, true) | |
860 | && oprs_unchanged_p (XEXP (dest, 0), insn, true)) | |
861 | { | |
862 | insert_expr_in_table (dest, insn); | |
863 | } | |
864 | } | |
865 | } | |
866 | \f | |
d447762f | 867 | |
78d140c9 | 868 | /* Create hash table of memory expressions available at end of basic |
d447762f | 869 | blocks. Basically you should think of this hash table as the |
870 | representation of AVAIL_OUT. This is the set of expressions that | |
871 | is generated in a basic block and not killed before the end of the | |
872 | same basic block. Notice that this is really a local computation. */ | |
78d140c9 | 873 | |
874 | static void | |
875 | compute_hash_table (void) | |
876 | { | |
877 | basic_block bb; | |
878 | ||
fc00614f | 879 | FOR_EACH_BB_FN (bb, cfun) |
78d140c9 | 880 | { |
cdace3a0 | 881 | rtx_insn *insn; |
78d140c9 | 882 | |
883 | /* First pass over the instructions records information used to | |
d447762f | 884 | determine when registers and memory are last set. |
885 | Since we compute a "local" AVAIL_OUT, reset the tables that | |
886 | help us keep track of what has been modified since the start | |
887 | of the block. */ | |
888 | reset_opr_set_tables (); | |
78d140c9 | 889 | FOR_BB_INSNS (bb, insn) |
890 | { | |
d447762f | 891 | if (INSN_P (insn)) |
892 | record_opr_changes (insn); | |
893 | } | |
78d140c9 | 894 | |
d447762f | 895 | /* The next pass actually builds the hash table. */ |
78d140c9 | 896 | FOR_BB_INSNS (bb, insn) |
897 | if (INSN_P (insn) && GET_CODE (PATTERN (insn)) == SET) | |
898 | hash_scan_set (insn); | |
899 | } | |
900 | } | |
901 | \f | |
902 | ||
903 | /* Check if register REG is killed in any insn waiting to be inserted on | |
904 | edge E. This function is required to check that our data flow analysis | |
905 | is still valid prior to commit_edge_insertions. */ | |
906 | ||
907 | static bool | |
908 | reg_killed_on_edge (rtx reg, edge e) | |
909 | { | |
ae5e6486 | 910 | rtx_insn *insn; |
78d140c9 | 911 | |
912 | for (insn = e->insns.r; insn; insn = NEXT_INSN (insn)) | |
913 | if (INSN_P (insn) && reg_set_p (reg, insn)) | |
914 | return true; | |
915 | ||
916 | return false; | |
917 | } | |
918 | ||
919 | /* Similar to above - check if register REG is used in any insn waiting | |
920 | to be inserted on edge E. | |
921 | Assumes no such insn can be a CALL_INSN; if so call reg_used_between_p | |
922 | with PREV(insn),NEXT(insn) instead of calling reg_overlap_mentioned_p. */ | |
923 | ||
924 | static bool | |
925 | reg_used_on_edge (rtx reg, edge e) | |
926 | { | |
ae5e6486 | 927 | rtx_insn *insn; |
78d140c9 | 928 | |
929 | for (insn = e->insns.r; insn; insn = NEXT_INSN (insn)) | |
930 | if (INSN_P (insn) && reg_overlap_mentioned_p (reg, PATTERN (insn))) | |
931 | return true; | |
932 | ||
933 | return false; | |
934 | } | |
935 | \f | |
78d140c9 | 936 | /* Return the loaded/stored register of a load/store instruction. */ |
937 | ||
938 | static rtx | |
cdace3a0 | 939 | get_avail_load_store_reg (rtx_insn *insn) |
78d140c9 | 940 | { |
876760f6 | 941 | if (REG_P (SET_DEST (PATTERN (insn)))) |
942 | /* A load. */ | |
9af5ce0c | 943 | return SET_DEST (PATTERN (insn)); |
876760f6 | 944 | else |
945 | { | |
946 | /* A store. */ | |
947 | gcc_assert (REG_P (SET_SRC (PATTERN (insn)))); | |
948 | return SET_SRC (PATTERN (insn)); | |
949 | } | |
78d140c9 | 950 | } |
951 | ||
952 | /* Return nonzero if the predecessors of BB are "well behaved". */ | |
953 | ||
954 | static bool | |
955 | bb_has_well_behaved_predecessors (basic_block bb) | |
956 | { | |
957 | edge pred; | |
cd665a06 | 958 | edge_iterator ei; |
78d140c9 | 959 | |
4c43a998 | 960 | if (EDGE_COUNT (bb->preds) == 0) |
78d140c9 | 961 | return false; |
962 | ||
cd665a06 | 963 | FOR_EACH_EDGE (pred, ei, bb->preds) |
78d140c9 | 964 | { |
965 | if ((pred->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (pred)) | |
966 | return false; | |
967 | ||
4c43a998 | 968 | if ((pred->flags & EDGE_ABNORMAL_CALL) && cfun->has_nonlocal_label) |
969 | return false; | |
970 | ||
91f71fa3 | 971 | if (tablejump_p (BB_END (pred->src), NULL, NULL)) |
78d140c9 | 972 | return false; |
973 | } | |
974 | return true; | |
975 | } | |
976 | ||
977 | ||
978 | /* Search for the occurrences of expression in BB. */ | |
979 | ||
980 | static struct occr* | |
d2ac64b1 | 981 | get_bb_avail_insn (basic_block bb, struct occr *orig_occr, int bitmap_index) |
78d140c9 | 982 | { |
d2ac64b1 | 983 | struct occr *occr = orig_occr; |
984 | ||
78d140c9 | 985 | for (; occr != NULL; occr = occr->next) |
986 | if (BLOCK_FOR_INSN (occr->insn) == bb) | |
987 | return occr; | |
d2ac64b1 | 988 | |
989 | /* If we could not find an occurrence in BB, see if BB | |
990 | has a single predecessor with an occurrence that is | |
991 | transparent through BB. */ | |
992 | if (single_pred_p (bb) | |
993 | && bitmap_bit_p (transp[bb->index], bitmap_index) | |
994 | && (occr = get_bb_avail_insn (single_pred (bb), orig_occr, bitmap_index))) | |
995 | { | |
996 | rtx avail_reg = get_avail_load_store_reg (occr->insn); | |
997 | if (!reg_set_between_p (avail_reg, | |
998 | PREV_INSN (BB_HEAD (bb)), | |
999 | NEXT_INSN (BB_END (bb))) | |
1000 | && !reg_killed_on_edge (avail_reg, single_pred_edge (bb))) | |
1001 | return occr; | |
1002 | } | |
1003 | ||
78d140c9 | 1004 | return NULL; |
1005 | } | |
1006 | ||
1007 | ||
d2ac64b1 | 1008 | /* This helper is called via htab_traverse. */ |
1009 | int | |
1010 | compute_expr_transp (expr **slot, FILE *dump_file ATTRIBUTE_UNUSED) | |
1011 | { | |
1012 | struct expr *expr = *slot; | |
1013 | ||
1014 | compute_transp (expr->expr, expr->bitmap_index, transp, | |
1015 | blocks_with_calls, modify_mem_list_set, | |
1016 | canon_modify_mem_list); | |
1017 | return 1; | |
1018 | } | |
1019 | ||
78d140c9 | 1020 | /* This handles the case where several stores feed a partially redundant |
1021 | load. It checks if the redundancy elimination is possible and if it's | |
d447762f | 1022 | worth it. |
1023 | ||
1024 | Redundancy elimination is possible if, | |
1025 | 1) None of the operands of an insn have been modified since the start | |
1026 | of the current basic block. | |
1027 | 2) In any predecessor of the current basic block, the same expression | |
1028 | is generated. | |
1029 | ||
1030 | See the function body for the heuristics that determine if eliminating | |
1031 | a redundancy is also worth doing, assuming it is possible. */ | |
78d140c9 | 1032 | |
1033 | static void | |
cdace3a0 | 1034 | eliminate_partially_redundant_load (basic_block bb, rtx_insn *insn, |
78d140c9 | 1035 | struct expr *expr) |
1036 | { | |
1037 | edge pred; | |
cdace3a0 | 1038 | rtx_insn *avail_insn = NULL; |
78d140c9 | 1039 | rtx avail_reg; |
1040 | rtx dest, pat; | |
1041 | struct occr *a_occr; | |
1042 | struct unoccr *occr, *avail_occrs = NULL; | |
1043 | struct unoccr *unoccr, *unavail_occrs = NULL, *rollback_unoccr = NULL; | |
1044 | int npred_ok = 0; | |
1045 | gcov_type ok_count = 0; /* Redundant load execution count. */ | |
1046 | gcov_type critical_count = 0; /* Execution count of critical edges. */ | |
cd665a06 | 1047 | edge_iterator ei; |
b0596095 | 1048 | bool critical_edge_split = false; |
78d140c9 | 1049 | |
1050 | /* The execution count of the loads to be added to make the | |
1051 | load fully redundant. */ | |
1052 | gcov_type not_ok_count = 0; | |
1053 | basic_block pred_bb; | |
1054 | ||
1055 | pat = PATTERN (insn); | |
1056 | dest = SET_DEST (pat); | |
1057 | ||
1058 | /* Check that the loaded register is not used, set, or killed from the | |
1059 | beginning of the block. */ | |
20128b13 | 1060 | if (reg_changed_after_insn_p (dest, 0) |
1061 | || reg_used_between_p (dest, PREV_INSN (BB_HEAD (bb)), insn)) | |
78d140c9 | 1062 | return; |
1063 | ||
1064 | /* Check potential for replacing load with copy for predecessors. */ | |
cd665a06 | 1065 | FOR_EACH_EDGE (pred, ei, bb->preds) |
78d140c9 | 1066 | { |
cdace3a0 | 1067 | rtx_insn *next_pred_bb_end; |
78d140c9 | 1068 | |
cdace3a0 | 1069 | avail_insn = NULL; |
b0596095 | 1070 | avail_reg = NULL_RTX; |
78d140c9 | 1071 | pred_bb = pred->src; |
d2ac64b1 | 1072 | for (a_occr = get_bb_avail_insn (pred_bb, |
1073 | expr->avail_occr, | |
1074 | expr->bitmap_index); | |
1075 | a_occr; | |
1076 | a_occr = get_bb_avail_insn (pred_bb, | |
1077 | a_occr->next, | |
1078 | expr->bitmap_index)) | |
78d140c9 | 1079 | { |
1080 | /* Check if the loaded register is not used. */ | |
1081 | avail_insn = a_occr->insn; | |
876760f6 | 1082 | avail_reg = get_avail_load_store_reg (avail_insn); |
1083 | gcc_assert (avail_reg); | |
48e1416a | 1084 | |
78d140c9 | 1085 | /* Make sure we can generate a move from register avail_reg to |
1086 | dest. */ | |
f9a00e9e | 1087 | rtx_insn *move = gen_move_insn (copy_rtx (dest), |
1088 | copy_rtx (avail_reg)); | |
e2f730a9 | 1089 | extract_insn (move); |
1090 | if (! constrain_operands (1, get_preferred_alternatives (insn, | |
1091 | pred_bb)) | |
78d140c9 | 1092 | || reg_killed_on_edge (avail_reg, pred) |
1093 | || reg_used_on_edge (dest, pred)) | |
1094 | { | |
1095 | avail_insn = NULL; | |
1096 | continue; | |
1097 | } | |
d2ac64b1 | 1098 | next_pred_bb_end = NEXT_INSN (BB_END (BLOCK_FOR_INSN (avail_insn))); |
20128b13 | 1099 | if (!reg_set_between_p (avail_reg, avail_insn, next_pred_bb_end)) |
78d140c9 | 1100 | /* AVAIL_INSN remains non-null. */ |
1101 | break; | |
1102 | else | |
1103 | avail_insn = NULL; | |
1104 | } | |
1105 | ||
1106 | if (EDGE_CRITICAL_P (pred)) | |
1107 | critical_count += pred->count; | |
1108 | ||
1109 | if (avail_insn != NULL_RTX) | |
1110 | { | |
1111 | npred_ok++; | |
1112 | ok_count += pred->count; | |
b0596095 | 1113 | if (! set_noop_p (PATTERN (gen_move_insn (copy_rtx (dest), |
1114 | copy_rtx (avail_reg))))) | |
1115 | { | |
1116 | /* Check if there is going to be a split. */ | |
1117 | if (EDGE_CRITICAL_P (pred)) | |
1118 | critical_edge_split = true; | |
1119 | } | |
1120 | else /* Its a dead move no need to generate. */ | |
1121 | continue; | |
78d140c9 | 1122 | occr = (struct unoccr *) obstack_alloc (&unoccr_obstack, |
beab9d47 | 1123 | sizeof (struct unoccr)); |
78d140c9 | 1124 | occr->insn = avail_insn; |
1125 | occr->pred = pred; | |
1126 | occr->next = avail_occrs; | |
1127 | avail_occrs = occr; | |
1128 | if (! rollback_unoccr) | |
1129 | rollback_unoccr = occr; | |
1130 | } | |
1131 | else | |
1132 | { | |
7063afc3 | 1133 | /* Adding a load on a critical edge will cause a split. */ |
b0596095 | 1134 | if (EDGE_CRITICAL_P (pred)) |
1135 | critical_edge_split = true; | |
78d140c9 | 1136 | not_ok_count += pred->count; |
1137 | unoccr = (struct unoccr *) obstack_alloc (&unoccr_obstack, | |
1138 | sizeof (struct unoccr)); | |
cdace3a0 | 1139 | unoccr->insn = NULL; |
78d140c9 | 1140 | unoccr->pred = pred; |
1141 | unoccr->next = unavail_occrs; | |
1142 | unavail_occrs = unoccr; | |
1143 | if (! rollback_unoccr) | |
1144 | rollback_unoccr = unoccr; | |
1145 | } | |
1146 | } | |
1147 | ||
1148 | if (/* No load can be replaced by copy. */ | |
1149 | npred_ok == 0 | |
48e1416a | 1150 | /* Prevent exploding the code. */ |
0bfd8d5c | 1151 | || (optimize_bb_for_size_p (bb) && npred_ok > 1) |
48e1416a | 1152 | /* If we don't have profile information we cannot tell if splitting |
b0596095 | 1153 | a critical edge is profitable or not so don't do it. */ |
1154 | || ((! profile_info || ! flag_branch_probabilities | |
1155 | || targetm.cannot_modify_jumps_p ()) | |
1156 | && critical_edge_split)) | |
78d140c9 | 1157 | goto cleanup; |
1158 | ||
1159 | /* Check if it's worth applying the partial redundancy elimination. */ | |
1160 | if (ok_count < GCSE_AFTER_RELOAD_PARTIAL_FRACTION * not_ok_count) | |
1161 | goto cleanup; | |
1162 | if (ok_count < GCSE_AFTER_RELOAD_CRITICAL_FRACTION * critical_count) | |
1163 | goto cleanup; | |
1164 | ||
1165 | /* Generate moves to the loaded register from where | |
1166 | the memory is available. */ | |
1167 | for (occr = avail_occrs; occr; occr = occr->next) | |
1168 | { | |
1169 | avail_insn = occr->insn; | |
1170 | pred = occr->pred; | |
1171 | /* Set avail_reg to be the register having the value of the | |
1172 | memory. */ | |
1173 | avail_reg = get_avail_load_store_reg (avail_insn); | |
876760f6 | 1174 | gcc_assert (avail_reg); |
78d140c9 | 1175 | |
1176 | insert_insn_on_edge (gen_move_insn (copy_rtx (dest), | |
1177 | copy_rtx (avail_reg)), | |
1178 | pred); | |
1179 | stats.moves_inserted++; | |
1180 | ||
1181 | if (dump_file) | |
1182 | fprintf (dump_file, | |
1183 | "generating move from %d to %d on edge from %d to %d\n", | |
1184 | REGNO (avail_reg), | |
1185 | REGNO (dest), | |
1186 | pred->src->index, | |
1187 | pred->dest->index); | |
1188 | } | |
1189 | ||
1190 | /* Regenerate loads where the memory is unavailable. */ | |
1191 | for (unoccr = unavail_occrs; unoccr; unoccr = unoccr->next) | |
1192 | { | |
1193 | pred = unoccr->pred; | |
1194 | insert_insn_on_edge (copy_insn (PATTERN (insn)), pred); | |
1195 | stats.copies_inserted++; | |
1196 | ||
1197 | if (dump_file) | |
1198 | { | |
1199 | fprintf (dump_file, | |
1200 | "generating on edge from %d to %d a copy of load: ", | |
1201 | pred->src->index, | |
1202 | pred->dest->index); | |
1203 | print_rtl (dump_file, PATTERN (insn)); | |
1204 | fprintf (dump_file, "\n"); | |
1205 | } | |
1206 | } | |
1207 | ||
1208 | /* Delete the insn if it is not available in this block and mark it | |
1209 | for deletion if it is available. If insn is available it may help | |
1210 | discover additional redundancies, so mark it for later deletion. */ | |
d2ac64b1 | 1211 | for (a_occr = get_bb_avail_insn (bb, expr->avail_occr, expr->bitmap_index); |
78d140c9 | 1212 | a_occr && (a_occr->insn != insn); |
d2ac64b1 | 1213 | a_occr = get_bb_avail_insn (bb, a_occr->next, expr->bitmap_index)) |
3c802a1e | 1214 | ; |
78d140c9 | 1215 | |
1216 | if (!a_occr) | |
b0596095 | 1217 | { |
1218 | stats.insns_deleted++; | |
1219 | ||
1220 | if (dump_file) | |
1221 | { | |
1222 | fprintf (dump_file, "deleting insn:\n"); | |
1223 | print_rtl_single (dump_file, insn); | |
1224 | fprintf (dump_file, "\n"); | |
1225 | } | |
1226 | delete_insn (insn); | |
1227 | } | |
78d140c9 | 1228 | else |
1229 | a_occr->deleted_p = 1; | |
1230 | ||
1231 | cleanup: | |
1232 | if (rollback_unoccr) | |
1233 | obstack_free (&unoccr_obstack, rollback_unoccr); | |
1234 | } | |
1235 | ||
1236 | /* Performing the redundancy elimination as described before. */ | |
1237 | ||
1238 | static void | |
1239 | eliminate_partially_redundant_loads (void) | |
1240 | { | |
cdace3a0 | 1241 | rtx_insn *insn; |
78d140c9 | 1242 | basic_block bb; |
1243 | ||
1244 | /* Note we start at block 1. */ | |
1245 | ||
34154e27 | 1246 | if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
78d140c9 | 1247 | return; |
1248 | ||
1249 | FOR_BB_BETWEEN (bb, | |
34154e27 | 1250 | ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb->next_bb, |
1251 | EXIT_BLOCK_PTR_FOR_FN (cfun), | |
78d140c9 | 1252 | next_bb) |
1253 | { | |
d447762f | 1254 | /* Don't try anything on basic blocks with strange predecessors. */ |
78d140c9 | 1255 | if (! bb_has_well_behaved_predecessors (bb)) |
1256 | continue; | |
1257 | ||
d447762f | 1258 | /* Do not try anything on cold basic blocks. */ |
f29b326e | 1259 | if (optimize_bb_for_size_p (bb)) |
78d140c9 | 1260 | continue; |
1261 | ||
d447762f | 1262 | /* Reset the table of things changed since the start of the current |
1263 | basic block. */ | |
78d140c9 | 1264 | reset_opr_set_tables (); |
1265 | ||
d447762f | 1266 | /* Look at all insns in the current basic block and see if there are |
1267 | any loads in it that we can record. */ | |
78d140c9 | 1268 | FOR_BB_INSNS (bb, insn) |
1269 | { | |
1270 | /* Is it a load - of the form (set (reg) (mem))? */ | |
1271 | if (NONJUMP_INSN_P (insn) | |
1272 | && GET_CODE (PATTERN (insn)) == SET | |
1273 | && REG_P (SET_DEST (PATTERN (insn))) | |
1274 | && MEM_P (SET_SRC (PATTERN (insn)))) | |
1275 | { | |
1276 | rtx pat = PATTERN (insn); | |
1277 | rtx src = SET_SRC (pat); | |
1278 | struct expr *expr; | |
1279 | ||
1280 | if (!MEM_VOLATILE_P (src) | |
1281 | && GET_MODE (src) != BLKmode | |
1282 | && general_operand (src, GET_MODE (src)) | |
1283 | /* Are the operands unchanged since the start of the | |
1284 | block? */ | |
1285 | && oprs_unchanged_p (src, insn, false) | |
cbeb677e | 1286 | && !(cfun->can_throw_non_call_exceptions && may_trap_p (src)) |
78d140c9 | 1287 | && !side_effects_p (src) |
1288 | /* Is the expression recorded? */ | |
1289 | && (expr = lookup_expr_in_table (src)) != NULL) | |
1290 | { | |
1291 | /* We now have a load (insn) and an available memory at | |
1292 | its BB start (expr). Try to remove the loads if it is | |
1293 | redundant. */ | |
1294 | eliminate_partially_redundant_load (bb, insn, expr); | |
1295 | } | |
1296 | } | |
1297 | ||
d447762f | 1298 | /* Keep track of everything modified by this insn, so that we |
1299 | know what has been modified since the start of the current | |
1300 | basic block. */ | |
78d140c9 | 1301 | if (INSN_P (insn)) |
d447762f | 1302 | record_opr_changes (insn); |
78d140c9 | 1303 | } |
1304 | } | |
1305 | ||
1306 | commit_edge_insertions (); | |
1307 | } | |
1308 | ||
1309 | /* Go over the expression hash table and delete insns that were | |
1310 | marked for later deletion. */ | |
1311 | ||
1312 | /* This helper is called via htab_traverse. */ | |
d9dd21a8 | 1313 | int |
1314 | delete_redundant_insns_1 (expr **slot, void *data ATTRIBUTE_UNUSED) | |
78d140c9 | 1315 | { |
d9dd21a8 | 1316 | struct expr *exprs = *slot; |
78d140c9 | 1317 | struct occr *occr; |
1318 | ||
d9dd21a8 | 1319 | for (occr = exprs->avail_occr; occr != NULL; occr = occr->next) |
78d140c9 | 1320 | { |
3072d30e | 1321 | if (occr->deleted_p && dbg_cnt (gcse2_delete)) |
78d140c9 | 1322 | { |
1323 | delete_insn (occr->insn); | |
1324 | stats.insns_deleted++; | |
1325 | ||
1326 | if (dump_file) | |
1327 | { | |
1328 | fprintf (dump_file, "deleting insn:\n"); | |
1329 | print_rtl_single (dump_file, occr->insn); | |
1330 | fprintf (dump_file, "\n"); | |
1331 | } | |
1332 | } | |
1333 | } | |
1334 | ||
1335 | return 1; | |
1336 | } | |
1337 | ||
1338 | static void | |
1339 | delete_redundant_insns (void) | |
1340 | { | |
c1f445d2 | 1341 | expr_table->traverse <void *, delete_redundant_insns_1> (NULL); |
78d140c9 | 1342 | if (dump_file) |
1343 | fprintf (dump_file, "\n"); | |
1344 | } | |
1345 | ||
1346 | /* Main entry point of the GCSE after reload - clean some redundant loads | |
1347 | due to spilling. */ | |
1348 | ||
7f80955e | 1349 | static void |
78d140c9 | 1350 | gcse_after_reload_main (rtx f ATTRIBUTE_UNUSED) |
1351 | { | |
5ee7391d | 1352 | |
78d140c9 | 1353 | memset (&stats, 0, sizeof (stats)); |
1354 | ||
f0b5f617 | 1355 | /* Allocate memory for this pass. |
78d140c9 | 1356 | Also computes and initializes the insns' CUIDs. */ |
1357 | alloc_mem (); | |
1358 | ||
1359 | /* We need alias analysis. */ | |
1360 | init_alias_analysis (); | |
1361 | ||
1362 | compute_hash_table (); | |
1363 | ||
1364 | if (dump_file) | |
1365 | dump_hash_table (dump_file); | |
1366 | ||
c1f445d2 | 1367 | if (expr_table->elements () > 0) |
78d140c9 | 1368 | { |
d2ac64b1 | 1369 | /* Knowing which MEMs are transparent through a block can signifiantly |
1370 | increase the number of redundant loads found. So compute transparency | |
1371 | information for each memory expression in the hash table. */ | |
1372 | df_analyze (); | |
1373 | /* This can not be part of the normal allocation routine because | |
1374 | we have to know the number of elements in the hash table. */ | |
1375 | transp = sbitmap_vector_alloc (last_basic_block_for_fn (cfun), | |
1376 | expr_table->elements ()); | |
1377 | bitmap_vector_ones (transp, last_basic_block_for_fn (cfun)); | |
1378 | expr_table->traverse <FILE *, compute_expr_transp> (dump_file); | |
78d140c9 | 1379 | eliminate_partially_redundant_loads (); |
1380 | delete_redundant_insns (); | |
d2ac64b1 | 1381 | sbitmap_vector_free (transp); |
78d140c9 | 1382 | |
1383 | if (dump_file) | |
1384 | { | |
1385 | fprintf (dump_file, "GCSE AFTER RELOAD stats:\n"); | |
1386 | fprintf (dump_file, "copies inserted: %d\n", stats.copies_inserted); | |
1387 | fprintf (dump_file, "moves inserted: %d\n", stats.moves_inserted); | |
1388 | fprintf (dump_file, "insns deleted: %d\n", stats.insns_deleted); | |
1389 | fprintf (dump_file, "\n\n"); | |
1390 | } | |
30c4e60d | 1391 | |
1392 | statistics_counter_event (cfun, "copies inserted", | |
1393 | stats.copies_inserted); | |
1394 | statistics_counter_event (cfun, "moves inserted", | |
1395 | stats.moves_inserted); | |
1396 | statistics_counter_event (cfun, "insns deleted", | |
1397 | stats.insns_deleted); | |
78d140c9 | 1398 | } |
48e1416a | 1399 | |
78d140c9 | 1400 | /* We are finished with alias. */ |
1401 | end_alias_analysis (); | |
1402 | ||
1403 | free_mem (); | |
1404 | } | |
1405 | ||
77fce4cd | 1406 | \f |
77fce4cd | 1407 | |
2a1990e9 | 1408 | static unsigned int |
77fce4cd | 1409 | rest_of_handle_gcse2 (void) |
1410 | { | |
1411 | gcse_after_reload_main (get_insns ()); | |
1412 | rebuild_jump_labels (get_insns ()); | |
2a1990e9 | 1413 | return 0; |
77fce4cd | 1414 | } |
1415 | ||
cbe8bda8 | 1416 | namespace { |
1417 | ||
1418 | const pass_data pass_data_gcse2 = | |
77fce4cd | 1419 | { |
cbe8bda8 | 1420 | RTL_PASS, /* type */ |
1421 | "gcse2", /* name */ | |
1422 | OPTGROUP_NONE, /* optinfo_flags */ | |
cbe8bda8 | 1423 | TV_GCSE_AFTER_RELOAD, /* tv_id */ |
1424 | 0, /* properties_required */ | |
1425 | 0, /* properties_provided */ | |
1426 | 0, /* properties_destroyed */ | |
1427 | 0, /* todo_flags_start */ | |
8b88439e | 1428 | 0, /* todo_flags_finish */ |
77fce4cd | 1429 | }; |
cbe8bda8 | 1430 | |
1431 | class pass_gcse2 : public rtl_opt_pass | |
1432 | { | |
1433 | public: | |
9af5ce0c | 1434 | pass_gcse2 (gcc::context *ctxt) |
1435 | : rtl_opt_pass (pass_data_gcse2, ctxt) | |
cbe8bda8 | 1436 | {} |
1437 | ||
1438 | /* opt_pass methods: */ | |
31315c24 | 1439 | virtual bool gate (function *fun) |
1440 | { | |
1441 | return (optimize > 0 && flag_gcse_after_reload | |
1442 | && optimize_function_for_speed_p (fun)); | |
1443 | } | |
1444 | ||
65b0537f | 1445 | virtual unsigned int execute (function *) { return rest_of_handle_gcse2 (); } |
cbe8bda8 | 1446 | |
1447 | }; // class pass_gcse2 | |
1448 | ||
1449 | } // anon namespace | |
1450 | ||
1451 | rtl_opt_pass * | |
1452 | make_pass_gcse2 (gcc::context *ctxt) | |
1453 | { | |
1454 | return new pass_gcse2 (ctxt); | |
1455 | } |