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07abdb66 | 1 | /* Global constant/copy propagation for RTL. |
2 | Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, | |
3 | 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9 | Software Foundation; either version 3, or (at your option) any later | |
10 | version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING3. If not see | |
19 | <http://www.gnu.org/licenses/>. */ | |
20 | ||
21 | #include "config.h" | |
22 | #include "system.h" | |
23 | #include "coretypes.h" | |
24 | #include "tm.h" | |
25 | #include "diagnostic-core.h" | |
26 | #include "toplev.h" | |
27 | ||
28 | #include "rtl.h" | |
29 | #include "tree.h" | |
30 | #include "tm_p.h" | |
31 | #include "regs.h" | |
32 | #include "hard-reg-set.h" | |
33 | #include "flags.h" | |
34 | #include "insn-config.h" | |
35 | #include "recog.h" | |
36 | #include "basic-block.h" | |
07abdb66 | 37 | #include "function.h" |
38 | #include "expr.h" | |
39 | #include "except.h" | |
40 | #include "params.h" | |
41 | #include "cselib.h" | |
42 | #include "intl.h" | |
43 | #include "obstack.h" | |
07abdb66 | 44 | #include "tree-pass.h" |
45 | #include "hashtab.h" | |
46 | #include "df.h" | |
47 | #include "dbgcnt.h" | |
48 | #include "target.h" | |
79f958cb | 49 | #include "cfgloop.h" |
07abdb66 | 50 | |
51 | \f | |
52 | /* An obstack for our working variables. */ | |
540960d1 | 53 | static struct obstack cprop_obstack; |
07abdb66 | 54 | |
07abdb66 | 55 | /* Occurrence of an expression. |
56 | There is one per basic block. If a pattern appears more than once the | |
57 | last appearance is used. */ | |
58 | ||
59 | struct occr | |
60 | { | |
61 | /* Next occurrence of this expression. */ | |
62 | struct occr *next; | |
63 | /* The insn that computes the expression. */ | |
64 | rtx insn; | |
65 | }; | |
66 | ||
67 | typedef struct occr *occr_t; | |
68 | DEF_VEC_P (occr_t); | |
69 | DEF_VEC_ALLOC_P (occr_t, heap); | |
70 | ||
63b7075c | 71 | /* Hash table entry for assignment expressions. */ |
202325b0 | 72 | |
73 | struct expr | |
74 | { | |
75 | /* The expression (DEST := SRC). */ | |
76 | rtx dest; | |
77 | rtx src; | |
78 | ||
79 | /* Index in the available expression bitmaps. */ | |
80 | int bitmap_index; | |
81 | /* Next entry with the same hash. */ | |
82 | struct expr *next_same_hash; | |
83 | /* List of available occurrence in basic blocks in the function. | |
84 | An "available occurrence" is one that is the last occurrence in the | |
63b7075c | 85 | basic block and whose operands are not modified by following statements |
86 | in the basic block [including this insn]. */ | |
202325b0 | 87 | struct occr *avail_occr; |
88 | }; | |
89 | ||
90 | /* Hash table for copy propagation expressions. | |
07abdb66 | 91 | Each hash table is an array of buckets. |
92 | ??? It is known that if it were an array of entries, structure elements | |
93 | `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is | |
94 | not clear whether in the final analysis a sufficient amount of memory would | |
95 | be saved as the size of the available expression bitmaps would be larger | |
96 | [one could build a mapping table without holes afterwards though]. | |
97 | Someday I'll perform the computation and figure it out. */ | |
98 | ||
99 | struct hash_table_d | |
100 | { | |
101 | /* The table itself. | |
102 | This is an array of `set_hash_table_size' elements. */ | |
103 | struct expr **table; | |
104 | ||
105 | /* Size of the hash table, in elements. */ | |
106 | unsigned int size; | |
107 | ||
108 | /* Number of hash table elements. */ | |
109 | unsigned int n_elems; | |
110 | }; | |
111 | ||
112 | /* Copy propagation hash table. */ | |
113 | static struct hash_table_d set_hash_table; | |
114 | ||
115 | /* Array of implicit set patterns indexed by basic block index. */ | |
116 | static rtx *implicit_sets; | |
117 | ||
522983c2 | 118 | /* Array of indexes of expressions for implicit set patterns indexed by basic |
119 | block index. In other words, implicit_set_indexes[i] is the bitmap_index | |
120 | of the expression whose RTX is implicit_sets[i]. */ | |
121 | static int *implicit_set_indexes; | |
122 | ||
07abdb66 | 123 | /* Bitmap containing one bit for each register in the program. |
124 | Used when performing GCSE to track which registers have been set since | |
45a41a6c | 125 | the start or end of the basic block while traversing that block. */ |
07abdb66 | 126 | static regset reg_set_bitmap; |
127 | ||
128 | /* Various variables for statistics gathering. */ | |
129 | ||
130 | /* Memory used in a pass. | |
131 | This isn't intended to be absolutely precise. Its intent is only | |
132 | to keep an eye on memory usage. */ | |
133 | static int bytes_used; | |
134 | ||
135 | /* Number of local constants propagated. */ | |
136 | static int local_const_prop_count; | |
137 | /* Number of local copies propagated. */ | |
138 | static int local_copy_prop_count; | |
139 | /* Number of global constants propagated. */ | |
140 | static int global_const_prop_count; | |
141 | /* Number of global copies propagated. */ | |
142 | static int global_copy_prop_count; | |
07abdb66 | 143 | |
540960d1 | 144 | #define GOBNEW(T) ((T *) cprop_alloc (sizeof (T))) |
145 | #define GOBNEWVAR(T, S) ((T *) cprop_alloc ((S))) | |
07abdb66 | 146 | |
147 | /* Cover function to obstack_alloc. */ | |
148 | ||
149 | static void * | |
540960d1 | 150 | cprop_alloc (unsigned long size) |
07abdb66 | 151 | { |
152 | bytes_used += size; | |
540960d1 | 153 | return obstack_alloc (&cprop_obstack, size); |
07abdb66 | 154 | } |
155 | \f | |
45a41a6c | 156 | /* Return nonzero if register X is unchanged from INSN to the end |
157 | of INSN's basic block. */ | |
07abdb66 | 158 | |
159 | static int | |
45a41a6c | 160 | reg_available_p (const_rtx x, const_rtx insn ATTRIBUTE_UNUSED) |
07abdb66 | 161 | { |
45a41a6c | 162 | return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x)); |
07abdb66 | 163 | } |
164 | ||
165 | /* Hash a set of register REGNO. | |
166 | ||
167 | Sets are hashed on the register that is set. This simplifies the PRE copy | |
168 | propagation code. | |
169 | ||
170 | ??? May need to make things more elaborate. Later, as necessary. */ | |
171 | ||
172 | static unsigned int | |
173 | hash_set (int regno, int hash_table_size) | |
174 | { | |
175 | unsigned int hash; | |
176 | ||
177 | hash = regno; | |
178 | return hash % hash_table_size; | |
179 | } | |
180 | ||
202325b0 | 181 | /* Insert assignment DEST:=SET from INSN in the hash table. |
182 | DEST is a register and SET is a register or a suitable constant. | |
183 | If the assignment is already present in the table, record it as | |
522983c2 | 184 | the last occurrence in INSN's basic block. |
185 | IMPLICIT is true if it's an implicit set, false otherwise. */ | |
07abdb66 | 186 | |
187 | static void | |
522983c2 | 188 | insert_set_in_table (rtx dest, rtx src, rtx insn, struct hash_table_d *table, |
189 | bool implicit) | |
07abdb66 | 190 | { |
202325b0 | 191 | bool found = false; |
07abdb66 | 192 | unsigned int hash; |
193 | struct expr *cur_expr, *last_expr = NULL; | |
194 | struct occr *cur_occr; | |
195 | ||
202325b0 | 196 | hash = hash_set (REGNO (dest), table->size); |
07abdb66 | 197 | |
202325b0 | 198 | for (cur_expr = table->table[hash]; cur_expr; |
199 | cur_expr = cur_expr->next_same_hash) | |
07abdb66 | 200 | { |
202325b0 | 201 | if (dest == cur_expr->dest |
202 | && src == cur_expr->src) | |
203 | { | |
204 | found = true; | |
205 | break; | |
206 | } | |
07abdb66 | 207 | last_expr = cur_expr; |
07abdb66 | 208 | } |
209 | ||
210 | if (! found) | |
211 | { | |
212 | cur_expr = GOBNEW (struct expr); | |
213 | bytes_used += sizeof (struct expr); | |
214 | if (table->table[hash] == NULL) | |
215 | /* This is the first pattern that hashed to this index. */ | |
216 | table->table[hash] = cur_expr; | |
217 | else | |
218 | /* Add EXPR to end of this hash chain. */ | |
219 | last_expr->next_same_hash = cur_expr; | |
220 | ||
221 | /* Set the fields of the expr element. | |
222 | We must copy X because it can be modified when copy propagation is | |
223 | performed on its operands. */ | |
202325b0 | 224 | cur_expr->dest = copy_rtx (dest); |
225 | cur_expr->src = copy_rtx (src); | |
07abdb66 | 226 | cur_expr->bitmap_index = table->n_elems++; |
227 | cur_expr->next_same_hash = NULL; | |
228 | cur_expr->avail_occr = NULL; | |
229 | } | |
230 | ||
231 | /* Now record the occurrence. */ | |
232 | cur_occr = cur_expr->avail_occr; | |
233 | ||
234 | if (cur_occr | |
235 | && BLOCK_FOR_INSN (cur_occr->insn) == BLOCK_FOR_INSN (insn)) | |
236 | { | |
237 | /* Found another instance of the expression in the same basic block. | |
238 | Prefer this occurrence to the currently recorded one. We want | |
239 | the last one in the block and the block is scanned from start | |
240 | to end. */ | |
241 | cur_occr->insn = insn; | |
242 | } | |
243 | else | |
244 | { | |
245 | /* First occurrence of this expression in this basic block. */ | |
246 | cur_occr = GOBNEW (struct occr); | |
247 | bytes_used += sizeof (struct occr); | |
248 | cur_occr->insn = insn; | |
249 | cur_occr->next = cur_expr->avail_occr; | |
250 | cur_expr->avail_occr = cur_occr; | |
251 | } | |
522983c2 | 252 | |
253 | /* Record bitmap_index of the implicit set in implicit_set_indexes. */ | |
254 | if (implicit) | |
255 | implicit_set_indexes[BLOCK_FOR_INSN(insn)->index] = cur_expr->bitmap_index; | |
07abdb66 | 256 | } |
257 | ||
45a41a6c | 258 | /* Determine whether the rtx X should be treated as a constant for CPROP. |
259 | Since X might be inserted more than once we have to take care that it | |
260 | is sharable. */ | |
07abdb66 | 261 | |
262 | static bool | |
540960d1 | 263 | cprop_constant_p (const_rtx x) |
07abdb66 | 264 | { |
07abdb66 | 265 | return CONSTANT_P (x) && (GET_CODE (x) != CONST || shared_const_p (x)); |
266 | } | |
267 | ||
522983c2 | 268 | /* Scan SET present in INSN and add an entry to the hash TABLE. |
269 | IMPLICIT is true if it's an implicit set, false otherwise. */ | |
07abdb66 | 270 | |
271 | static void | |
522983c2 | 272 | hash_scan_set (rtx set, rtx insn, struct hash_table_d *table, bool implicit) |
07abdb66 | 273 | { |
63b7075c | 274 | rtx src = SET_SRC (set); |
275 | rtx dest = SET_DEST (set); | |
07abdb66 | 276 | |
45a41a6c | 277 | if (REG_P (dest) |
278 | && ! HARD_REGISTER_P (dest) | |
279 | && reg_available_p (dest, insn) | |
280 | && can_copy_p (GET_MODE (dest))) | |
07abdb66 | 281 | { |
07abdb66 | 282 | /* See if a REG_EQUAL note shows this equivalent to a simpler expression. |
283 | ||
45a41a6c | 284 | This allows us to do a single CPROP pass and still eliminate |
07abdb66 | 285 | redundant constants, addresses or other expressions that are |
286 | constructed with multiple instructions. | |
287 | ||
288 | However, keep the original SRC if INSN is a simple reg-reg move. In | |
289 | In this case, there will almost always be a REG_EQUAL note on the | |
290 | insn that sets SRC. By recording the REG_EQUAL value here as SRC | |
45a41a6c | 291 | for INSN, we miss copy propagation opportunities. |
07abdb66 | 292 | |
293 | Note that this does not impede profitable constant propagations. We | |
202325b0 | 294 | "look through" reg-reg sets in lookup_set. */ |
45a41a6c | 295 | rtx note = find_reg_equal_equiv_note (insn); |
07abdb66 | 296 | if (note != 0 |
297 | && REG_NOTE_KIND (note) == REG_EQUAL | |
298 | && !REG_P (src) | |
540960d1 | 299 | && cprop_constant_p (XEXP (note, 0))) |
63b7075c | 300 | src = XEXP (note, 0), set = gen_rtx_SET (VOIDmode, dest, src); |
07abdb66 | 301 | |
302 | /* Record sets for constant/copy propagation. */ | |
45a41a6c | 303 | if ((REG_P (src) |
304 | && src != dest | |
305 | && ! HARD_REGISTER_P (src) | |
306 | && reg_available_p (src, insn)) | |
540960d1 | 307 | || cprop_constant_p (src)) |
522983c2 | 308 | insert_set_in_table (dest, src, insn, table, implicit); |
07abdb66 | 309 | } |
310 | } | |
311 | ||
63b7075c | 312 | /* Process INSN and add hash table entries as appropriate. */ |
07abdb66 | 313 | |
314 | static void | |
315 | hash_scan_insn (rtx insn, struct hash_table_d *table) | |
316 | { | |
317 | rtx pat = PATTERN (insn); | |
318 | int i; | |
319 | ||
320 | /* Pick out the sets of INSN and for other forms of instructions record | |
321 | what's been modified. */ | |
322 | ||
323 | if (GET_CODE (pat) == SET) | |
522983c2 | 324 | hash_scan_set (pat, insn, table, false); |
07abdb66 | 325 | else if (GET_CODE (pat) == PARALLEL) |
326 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
327 | { | |
328 | rtx x = XVECEXP (pat, 0, i); | |
329 | ||
330 | if (GET_CODE (x) == SET) | |
522983c2 | 331 | hash_scan_set (x, insn, table, false); |
07abdb66 | 332 | } |
333 | } | |
334 | ||
63b7075c | 335 | /* Dump the hash table TABLE to file FILE under the name NAME. */ |
336 | ||
07abdb66 | 337 | static void |
338 | dump_hash_table (FILE *file, const char *name, struct hash_table_d *table) | |
339 | { | |
340 | int i; | |
341 | /* Flattened out table, so it's printed in proper order. */ | |
342 | struct expr **flat_table; | |
343 | unsigned int *hash_val; | |
344 | struct expr *expr; | |
345 | ||
346 | flat_table = XCNEWVEC (struct expr *, table->n_elems); | |
347 | hash_val = XNEWVEC (unsigned int, table->n_elems); | |
348 | ||
349 | for (i = 0; i < (int) table->size; i++) | |
350 | for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash) | |
351 | { | |
352 | flat_table[expr->bitmap_index] = expr; | |
353 | hash_val[expr->bitmap_index] = i; | |
354 | } | |
355 | ||
356 | fprintf (file, "%s hash table (%d buckets, %d entries)\n", | |
357 | name, table->size, table->n_elems); | |
358 | ||
359 | for (i = 0; i < (int) table->n_elems; i++) | |
360 | if (flat_table[i] != 0) | |
361 | { | |
362 | expr = flat_table[i]; | |
363 | fprintf (file, "Index %d (hash value %d)\n ", | |
364 | expr->bitmap_index, hash_val[i]); | |
202325b0 | 365 | print_rtl (file, expr->dest); |
366 | fprintf (file, " := "); | |
367 | print_rtl (file, expr->src); | |
07abdb66 | 368 | fprintf (file, "\n"); |
369 | } | |
370 | ||
371 | fprintf (file, "\n"); | |
372 | ||
373 | free (flat_table); | |
374 | free (hash_val); | |
375 | } | |
376 | ||
45a41a6c | 377 | /* Record as unavailable all registers that are DEF operands of INSN. */ |
63b7075c | 378 | |
07abdb66 | 379 | static void |
45a41a6c | 380 | make_set_regs_unavailable (rtx insn) |
07abdb66 | 381 | { |
45a41a6c | 382 | struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn); |
383 | df_ref *def_rec; | |
07abdb66 | 384 | |
45a41a6c | 385 | for (def_rec = DF_INSN_INFO_DEFS (insn_info); *def_rec; def_rec++) |
386 | SET_REGNO_REG_SET (reg_set_bitmap, DF_REF_REGNO (*def_rec)); | |
07abdb66 | 387 | } |
388 | ||
63b7075c | 389 | /* Top level function to create an assignment hash table. |
07abdb66 | 390 | |
391 | Assignment entries are placed in the hash table if | |
392 | - they are of the form (set (pseudo-reg) src), | |
393 | - src is something we want to perform const/copy propagation on, | |
394 | - none of the operands or target are subsequently modified in the block | |
395 | ||
396 | Currently src must be a pseudo-reg or a const_int. | |
397 | ||
398 | TABLE is the table computed. */ | |
399 | ||
400 | static void | |
401 | compute_hash_table_work (struct hash_table_d *table) | |
402 | { | |
45a41a6c | 403 | basic_block bb; |
07abdb66 | 404 | |
540960d1 | 405 | /* Allocate vars to track sets of regs. */ |
406 | reg_set_bitmap = ALLOC_REG_SET (NULL); | |
407 | ||
45a41a6c | 408 | FOR_EACH_BB (bb) |
07abdb66 | 409 | { |
410 | rtx insn; | |
07abdb66 | 411 | |
45a41a6c | 412 | /* Reset tables used to keep track of what's not yet invalid [since |
413 | the end of the block]. */ | |
414 | CLEAR_REG_SET (reg_set_bitmap); | |
415 | ||
416 | /* Go over all insns from the last to the first. This is convenient | |
417 | for tracking available registers, i.e. not set between INSN and | |
418 | the end of the basic block BB. */ | |
419 | FOR_BB_INSNS_REVERSE (bb, insn) | |
420 | { | |
421 | /* Only real insns are interesting. */ | |
07abdb66 | 422 | if (!NONDEBUG_INSN_P (insn)) |
423 | continue; | |
424 | ||
45a41a6c | 425 | /* Record interesting sets from INSN in the hash table. */ |
426 | hash_scan_insn (insn, table); | |
07abdb66 | 427 | |
45a41a6c | 428 | /* Any registers set in INSN will make SETs above it not AVAIL. */ |
429 | make_set_regs_unavailable (insn); | |
07abdb66 | 430 | } |
431 | ||
45a41a6c | 432 | /* Insert implicit sets in the hash table, pretending they appear as |
433 | insns at the head of the basic block. */ | |
434 | if (implicit_sets[bb->index] != NULL_RTX) | |
522983c2 | 435 | hash_scan_set (implicit_sets[bb->index], BB_HEAD (bb), table, true); |
07abdb66 | 436 | } |
540960d1 | 437 | |
438 | FREE_REG_SET (reg_set_bitmap); | |
07abdb66 | 439 | } |
440 | ||
441 | /* Allocate space for the set/expr hash TABLE. | |
442 | It is used to determine the number of buckets to use. */ | |
443 | ||
444 | static void | |
445 | alloc_hash_table (struct hash_table_d *table) | |
446 | { | |
447 | int n; | |
448 | ||
449 | n = get_max_insn_count (); | |
450 | ||
451 | table->size = n / 4; | |
452 | if (table->size < 11) | |
453 | table->size = 11; | |
454 | ||
455 | /* Attempt to maintain efficient use of hash table. | |
456 | Making it an odd number is simplest for now. | |
457 | ??? Later take some measurements. */ | |
458 | table->size |= 1; | |
459 | n = table->size * sizeof (struct expr *); | |
540960d1 | 460 | table->table = XNEWVAR (struct expr *, n); |
07abdb66 | 461 | } |
462 | ||
463 | /* Free things allocated by alloc_hash_table. */ | |
464 | ||
465 | static void | |
466 | free_hash_table (struct hash_table_d *table) | |
467 | { | |
468 | free (table->table); | |
469 | } | |
470 | ||
471 | /* Compute the hash TABLE for doing copy/const propagation or | |
472 | expression hash table. */ | |
473 | ||
474 | static void | |
475 | compute_hash_table (struct hash_table_d *table) | |
476 | { | |
477 | /* Initialize count of number of entries in hash table. */ | |
478 | table->n_elems = 0; | |
479 | memset (table->table, 0, table->size * sizeof (struct expr *)); | |
480 | ||
481 | compute_hash_table_work (table); | |
482 | } | |
483 | \f | |
484 | /* Expression tracking support. */ | |
485 | ||
486 | /* Lookup REGNO in the set TABLE. The result is a pointer to the | |
487 | table entry, or NULL if not found. */ | |
488 | ||
489 | static struct expr * | |
490 | lookup_set (unsigned int regno, struct hash_table_d *table) | |
491 | { | |
492 | unsigned int hash = hash_set (regno, table->size); | |
493 | struct expr *expr; | |
494 | ||
495 | expr = table->table[hash]; | |
496 | ||
202325b0 | 497 | while (expr && REGNO (expr->dest) != regno) |
07abdb66 | 498 | expr = expr->next_same_hash; |
499 | ||
500 | return expr; | |
501 | } | |
502 | ||
503 | /* Return the next entry for REGNO in list EXPR. */ | |
504 | ||
505 | static struct expr * | |
506 | next_set (unsigned int regno, struct expr *expr) | |
507 | { | |
508 | do | |
509 | expr = expr->next_same_hash; | |
202325b0 | 510 | while (expr && REGNO (expr->dest) != regno); |
07abdb66 | 511 | |
512 | return expr; | |
513 | } | |
514 | ||
515 | /* Reset tables used to keep track of what's still available [since the | |
516 | start of the block]. */ | |
517 | ||
518 | static void | |
519 | reset_opr_set_tables (void) | |
520 | { | |
521 | /* Maintain a bitmap of which regs have been set since beginning of | |
522 | the block. */ | |
523 | CLEAR_REG_SET (reg_set_bitmap); | |
524 | } | |
525 | ||
c8a32de3 | 526 | /* Return nonzero if the register X has not been set yet [since the |
527 | start of the basic block containing INSN]. */ | |
07abdb66 | 528 | |
529 | static int | |
c8a32de3 | 530 | reg_not_set_p (const_rtx x, const_rtx insn ATTRIBUTE_UNUSED) |
07abdb66 | 531 | { |
c8a32de3 | 532 | return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x)); |
07abdb66 | 533 | } |
534 | ||
535 | /* Record things set by INSN. | |
c8a32de3 | 536 | This data is used by reg_not_set_p. */ |
07abdb66 | 537 | |
538 | static void | |
539 | mark_oprs_set (rtx insn) | |
540 | { | |
c8a32de3 | 541 | struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn); |
542 | df_ref *def_rec; | |
07abdb66 | 543 | |
c8a32de3 | 544 | for (def_rec = DF_INSN_INFO_DEFS (insn_info); *def_rec; def_rec++) |
545 | SET_REGNO_REG_SET (reg_set_bitmap, DF_REF_REGNO (*def_rec)); | |
07abdb66 | 546 | } |
07abdb66 | 547 | \f |
548 | /* Compute copy/constant propagation working variables. */ | |
549 | ||
550 | /* Local properties of assignments. */ | |
63b7075c | 551 | static sbitmap *cprop_avloc; |
552 | static sbitmap *cprop_kill; | |
07abdb66 | 553 | |
554 | /* Global properties of assignments (computed from the local properties). */ | |
555 | static sbitmap *cprop_avin; | |
556 | static sbitmap *cprop_avout; | |
557 | ||
558 | /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of | |
559 | basic blocks. N_SETS is the number of sets. */ | |
560 | ||
561 | static void | |
562 | alloc_cprop_mem (int n_blocks, int n_sets) | |
563 | { | |
63b7075c | 564 | cprop_avloc = sbitmap_vector_alloc (n_blocks, n_sets); |
565 | cprop_kill = sbitmap_vector_alloc (n_blocks, n_sets); | |
07abdb66 | 566 | |
567 | cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets); | |
568 | cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets); | |
569 | } | |
570 | ||
571 | /* Free vars used by copy/const propagation. */ | |
572 | ||
573 | static void | |
574 | free_cprop_mem (void) | |
575 | { | |
63b7075c | 576 | sbitmap_vector_free (cprop_avloc); |
577 | sbitmap_vector_free (cprop_kill); | |
07abdb66 | 578 | sbitmap_vector_free (cprop_avin); |
579 | sbitmap_vector_free (cprop_avout); | |
580 | } | |
581 | ||
07abdb66 | 582 | /* Compute the local properties of each recorded expression. |
583 | ||
584 | Local properties are those that are defined by the block, irrespective of | |
585 | other blocks. | |
586 | ||
63b7075c | 587 | An expression is killed in a block if its operands, either DEST or SRC, are |
588 | modified in the block. | |
07abdb66 | 589 | |
590 | An expression is computed (locally available) in a block if it is computed | |
591 | at least once and expression would contain the same value if the | |
592 | computation was moved to the end of the block. | |
593 | ||
63b7075c | 594 | KILL and COMP are destination sbitmaps for recording local properties. */ |
07abdb66 | 595 | |
596 | static void | |
63b7075c | 597 | compute_local_properties (sbitmap *kill, sbitmap *comp, |
07abdb66 | 598 | struct hash_table_d *table) |
599 | { | |
600 | unsigned int i; | |
601 | ||
202325b0 | 602 | /* Initialize the bitmaps that were passed in. */ |
53c5d9d4 | 603 | bitmap_vector_clear (kill, last_basic_block); |
604 | bitmap_vector_clear (comp, last_basic_block); | |
07abdb66 | 605 | |
606 | for (i = 0; i < table->size; i++) | |
607 | { | |
608 | struct expr *expr; | |
609 | ||
610 | for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash) | |
611 | { | |
612 | int indx = expr->bitmap_index; | |
202325b0 | 613 | df_ref def; |
07abdb66 | 614 | struct occr *occr; |
615 | ||
63b7075c | 616 | /* For each definition of the destination pseudo-reg, the expression |
617 | is killed in the block where the definition is. */ | |
202325b0 | 618 | for (def = DF_REG_DEF_CHAIN (REGNO (expr->dest)); |
619 | def; def = DF_REF_NEXT_REG (def)) | |
63b7075c | 620 | SET_BIT (kill[DF_REF_BB (def)->index], indx); |
621 | ||
622 | /* If the source is a pseudo-reg, for each definition of the source, | |
623 | the expression is killed in the block where the definition is. */ | |
202325b0 | 624 | if (REG_P (expr->src)) |
625 | for (def = DF_REG_DEF_CHAIN (REGNO (expr->src)); | |
626 | def; def = DF_REF_NEXT_REG (def)) | |
63b7075c | 627 | SET_BIT (kill[DF_REF_BB (def)->index], indx); |
07abdb66 | 628 | |
629 | /* The occurrences recorded in avail_occr are exactly those that | |
63b7075c | 630 | are locally available in the block where they are. */ |
202325b0 | 631 | for (occr = expr->avail_occr; occr != NULL; occr = occr->next) |
632 | { | |
633 | SET_BIT (comp[BLOCK_FOR_INSN (occr->insn)->index], indx); | |
634 | } | |
07abdb66 | 635 | } |
636 | } | |
637 | } | |
638 | \f | |
639 | /* Hash table support. */ | |
640 | ||
641 | /* Top level routine to do the dataflow analysis needed by copy/const | |
642 | propagation. */ | |
643 | ||
644 | static void | |
645 | compute_cprop_data (void) | |
646 | { | |
522983c2 | 647 | basic_block bb; |
648 | ||
63b7075c | 649 | compute_local_properties (cprop_kill, cprop_avloc, &set_hash_table); |
650 | compute_available (cprop_avloc, cprop_kill, cprop_avout, cprop_avin); | |
522983c2 | 651 | |
652 | /* Merge implicit sets into CPROP_AVIN. They are always available at the | |
653 | entry of their basic block. We need to do this because 1) implicit sets | |
654 | aren't recorded for the local pass so they cannot be propagated within | |
655 | their basic block by this pass and 2) the global pass would otherwise | |
656 | propagate them only in the successors of their basic block. */ | |
657 | FOR_EACH_BB (bb) | |
658 | { | |
659 | int index = implicit_set_indexes[bb->index]; | |
660 | if (index != -1) | |
661 | SET_BIT (cprop_avin[bb->index], index); | |
662 | } | |
07abdb66 | 663 | } |
664 | \f | |
665 | /* Copy/constant propagation. */ | |
666 | ||
667 | /* Maximum number of register uses in an insn that we handle. */ | |
668 | #define MAX_USES 8 | |
669 | ||
748fd717 | 670 | /* Table of uses (registers, both hard and pseudo) found in an insn. |
07abdb66 | 671 | Allocated statically to avoid alloc/free complexity and overhead. */ |
748fd717 | 672 | static rtx reg_use_table[MAX_USES]; |
07abdb66 | 673 | |
674 | /* Index into `reg_use_table' while building it. */ | |
748fd717 | 675 | static unsigned reg_use_count; |
07abdb66 | 676 | |
677 | /* Set up a list of register numbers used in INSN. The found uses are stored | |
678 | in `reg_use_table'. `reg_use_count' is initialized to zero before entry, | |
679 | and contains the number of uses in the table upon exit. | |
680 | ||
681 | ??? If a register appears multiple times we will record it multiple times. | |
682 | This doesn't hurt anything but it will slow things down. */ | |
683 | ||
684 | static void | |
685 | find_used_regs (rtx *xptr, void *data ATTRIBUTE_UNUSED) | |
686 | { | |
687 | int i, j; | |
688 | enum rtx_code code; | |
689 | const char *fmt; | |
690 | rtx x = *xptr; | |
691 | ||
692 | /* repeat is used to turn tail-recursion into iteration since GCC | |
693 | can't do it when there's no return value. */ | |
694 | repeat: | |
695 | if (x == 0) | |
696 | return; | |
697 | ||
698 | code = GET_CODE (x); | |
699 | if (REG_P (x)) | |
700 | { | |
701 | if (reg_use_count == MAX_USES) | |
702 | return; | |
703 | ||
748fd717 | 704 | reg_use_table[reg_use_count] = x; |
07abdb66 | 705 | reg_use_count++; |
706 | } | |
707 | ||
708 | /* Recursively scan the operands of this expression. */ | |
709 | ||
710 | for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--) | |
711 | { | |
712 | if (fmt[i] == 'e') | |
713 | { | |
714 | /* If we are about to do the last recursive call | |
715 | needed at this level, change it into iteration. | |
716 | This function is called enough to be worth it. */ | |
717 | if (i == 0) | |
718 | { | |
719 | x = XEXP (x, 0); | |
720 | goto repeat; | |
721 | } | |
722 | ||
723 | find_used_regs (&XEXP (x, i), data); | |
724 | } | |
725 | else if (fmt[i] == 'E') | |
726 | for (j = 0; j < XVECLEN (x, i); j++) | |
727 | find_used_regs (&XVECEXP (x, i, j), data); | |
728 | } | |
729 | } | |
730 | ||
a1981f91 | 731 | /* Try to replace all uses of FROM in INSN with TO. |
732 | Return nonzero if successful. */ | |
07abdb66 | 733 | |
734 | static int | |
735 | try_replace_reg (rtx from, rtx to, rtx insn) | |
736 | { | |
737 | rtx note = find_reg_equal_equiv_note (insn); | |
738 | rtx src = 0; | |
739 | int success = 0; | |
740 | rtx set = single_set (insn); | |
741 | ||
742 | /* Usually we substitute easy stuff, so we won't copy everything. | |
743 | We however need to take care to not duplicate non-trivial CONST | |
744 | expressions. */ | |
745 | to = copy_rtx (to); | |
746 | ||
747 | validate_replace_src_group (from, to, insn); | |
748 | if (num_changes_pending () && apply_change_group ()) | |
749 | success = 1; | |
750 | ||
751 | /* Try to simplify SET_SRC if we have substituted a constant. */ | |
752 | if (success && set && CONSTANT_P (to)) | |
753 | { | |
754 | src = simplify_rtx (SET_SRC (set)); | |
755 | ||
756 | if (src) | |
757 | validate_change (insn, &SET_SRC (set), src, 0); | |
758 | } | |
759 | ||
760 | /* If there is already a REG_EQUAL note, update the expression in it | |
761 | with our replacement. */ | |
762 | if (note != 0 && REG_NOTE_KIND (note) == REG_EQUAL) | |
763 | set_unique_reg_note (insn, REG_EQUAL, | |
764 | simplify_replace_rtx (XEXP (note, 0), from, to)); | |
765 | if (!success && set && reg_mentioned_p (from, SET_SRC (set))) | |
766 | { | |
63b7075c | 767 | /* If above failed and this is a single set, try to simplify the source |
768 | of the set given our substitution. We could perhaps try this for | |
769 | multiple SETs, but it probably won't buy us anything. */ | |
07abdb66 | 770 | src = simplify_replace_rtx (SET_SRC (set), from, to); |
771 | ||
772 | if (!rtx_equal_p (src, SET_SRC (set)) | |
773 | && validate_change (insn, &SET_SRC (set), src, 0)) | |
774 | success = 1; | |
775 | ||
776 | /* If we've failed perform the replacement, have a single SET to | |
777 | a REG destination and don't yet have a note, add a REG_EQUAL note | |
778 | to not lose information. */ | |
779 | if (!success && note == 0 && set != 0 && REG_P (SET_DEST (set))) | |
780 | note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src)); | |
781 | } | |
782 | ||
a1981f91 | 783 | if (set && MEM_P (SET_DEST (set)) && reg_mentioned_p (from, SET_DEST (set))) |
784 | { | |
785 | /* Registers can also appear as uses in SET_DEST if it is a MEM. | |
786 | We could perhaps try this for multiple SETs, but it probably | |
787 | won't buy us anything. */ | |
788 | rtx dest = simplify_replace_rtx (SET_DEST (set), from, to); | |
63b7075c | 789 | |
a1981f91 | 790 | if (!rtx_equal_p (dest, SET_DEST (set)) |
791 | && validate_change (insn, &SET_DEST (set), dest, 0)) | |
792 | success = 1; | |
793 | } | |
794 | ||
07abdb66 | 795 | /* REG_EQUAL may get simplified into register. |
796 | We don't allow that. Remove that note. This code ought | |
797 | not to happen, because previous code ought to synthesize | |
798 | reg-reg move, but be on the safe side. */ | |
799 | if (note && REG_NOTE_KIND (note) == REG_EQUAL && REG_P (XEXP (note, 0))) | |
800 | remove_note (insn, note); | |
801 | ||
802 | return success; | |
803 | } | |
804 | ||
63b7075c | 805 | /* Find a set of REGNOs that are available on entry to INSN's block. Return |
07abdb66 | 806 | NULL no such set is found. */ |
807 | ||
808 | static struct expr * | |
809 | find_avail_set (int regno, rtx insn) | |
810 | { | |
811 | /* SET1 contains the last set found that can be returned to the caller for | |
812 | use in a substitution. */ | |
813 | struct expr *set1 = 0; | |
814 | ||
815 | /* Loops are not possible here. To get a loop we would need two sets | |
816 | available at the start of the block containing INSN. i.e. we would | |
817 | need two sets like this available at the start of the block: | |
818 | ||
819 | (set (reg X) (reg Y)) | |
820 | (set (reg Y) (reg X)) | |
821 | ||
822 | This can not happen since the set of (reg Y) would have killed the | |
823 | set of (reg X) making it unavailable at the start of this block. */ | |
824 | while (1) | |
825 | { | |
826 | rtx src; | |
827 | struct expr *set = lookup_set (regno, &set_hash_table); | |
828 | ||
829 | /* Find a set that is available at the start of the block | |
830 | which contains INSN. */ | |
831 | while (set) | |
832 | { | |
833 | if (TEST_BIT (cprop_avin[BLOCK_FOR_INSN (insn)->index], | |
834 | set->bitmap_index)) | |
835 | break; | |
836 | set = next_set (regno, set); | |
837 | } | |
838 | ||
839 | /* If no available set was found we've reached the end of the | |
840 | (possibly empty) copy chain. */ | |
841 | if (set == 0) | |
842 | break; | |
843 | ||
202325b0 | 844 | src = set->src; |
07abdb66 | 845 | |
846 | /* We know the set is available. | |
847 | Now check that SRC is locally anticipatable (i.e. none of the | |
848 | source operands have changed since the start of the block). | |
849 | ||
850 | If the source operand changed, we may still use it for the next | |
851 | iteration of this loop, but we may not use it for substitutions. */ | |
852 | ||
540960d1 | 853 | if (cprop_constant_p (src) || reg_not_set_p (src, insn)) |
07abdb66 | 854 | set1 = set; |
855 | ||
856 | /* If the source of the set is anything except a register, then | |
857 | we have reached the end of the copy chain. */ | |
858 | if (! REG_P (src)) | |
859 | break; | |
860 | ||
861 | /* Follow the copy chain, i.e. start another iteration of the loop | |
862 | and see if we have an available copy into SRC. */ | |
863 | regno = REGNO (src); | |
864 | } | |
865 | ||
866 | /* SET1 holds the last set that was available and anticipatable at | |
867 | INSN. */ | |
868 | return set1; | |
869 | } | |
870 | ||
871 | /* Subroutine of cprop_insn that tries to propagate constants into | |
872 | JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL | |
873 | it is the instruction that immediately precedes JUMP, and must be a | |
874 | single SET of a register. FROM is what we will try to replace, | |
63b7075c | 875 | SRC is the constant we will try to substitute for it. Return nonzero |
07abdb66 | 876 | if a change was made. */ |
877 | ||
878 | static int | |
879 | cprop_jump (basic_block bb, rtx setcc, rtx jump, rtx from, rtx src) | |
880 | { | |
881 | rtx new_rtx, set_src, note_src; | |
882 | rtx set = pc_set (jump); | |
883 | rtx note = find_reg_equal_equiv_note (jump); | |
884 | ||
885 | if (note) | |
886 | { | |
887 | note_src = XEXP (note, 0); | |
888 | if (GET_CODE (note_src) == EXPR_LIST) | |
889 | note_src = NULL_RTX; | |
890 | } | |
891 | else note_src = NULL_RTX; | |
892 | ||
893 | /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */ | |
894 | set_src = note_src ? note_src : SET_SRC (set); | |
895 | ||
896 | /* First substitute the SETCC condition into the JUMP instruction, | |
897 | then substitute that given values into this expanded JUMP. */ | |
898 | if (setcc != NULL_RTX | |
899 | && !modified_between_p (from, setcc, jump) | |
900 | && !modified_between_p (src, setcc, jump)) | |
901 | { | |
902 | rtx setcc_src; | |
903 | rtx setcc_set = single_set (setcc); | |
904 | rtx setcc_note = find_reg_equal_equiv_note (setcc); | |
905 | setcc_src = (setcc_note && GET_CODE (XEXP (setcc_note, 0)) != EXPR_LIST) | |
906 | ? XEXP (setcc_note, 0) : SET_SRC (setcc_set); | |
907 | set_src = simplify_replace_rtx (set_src, SET_DEST (setcc_set), | |
908 | setcc_src); | |
909 | } | |
910 | else | |
911 | setcc = NULL_RTX; | |
912 | ||
913 | new_rtx = simplify_replace_rtx (set_src, from, src); | |
914 | ||
915 | /* If no simplification can be made, then try the next register. */ | |
916 | if (rtx_equal_p (new_rtx, SET_SRC (set))) | |
917 | return 0; | |
918 | ||
919 | /* If this is now a no-op delete it, otherwise this must be a valid insn. */ | |
920 | if (new_rtx == pc_rtx) | |
921 | delete_insn (jump); | |
922 | else | |
923 | { | |
924 | /* Ensure the value computed inside the jump insn to be equivalent | |
925 | to one computed by setcc. */ | |
926 | if (setcc && modified_in_p (new_rtx, setcc)) | |
927 | return 0; | |
928 | if (! validate_unshare_change (jump, &SET_SRC (set), new_rtx, 0)) | |
929 | { | |
930 | /* When (some) constants are not valid in a comparison, and there | |
931 | are two registers to be replaced by constants before the entire | |
932 | comparison can be folded into a constant, we need to keep | |
933 | intermediate information in REG_EQUAL notes. For targets with | |
934 | separate compare insns, such notes are added by try_replace_reg. | |
935 | When we have a combined compare-and-branch instruction, however, | |
936 | we need to attach a note to the branch itself to make this | |
937 | optimization work. */ | |
938 | ||
939 | if (!rtx_equal_p (new_rtx, note_src)) | |
940 | set_unique_reg_note (jump, REG_EQUAL, copy_rtx (new_rtx)); | |
941 | return 0; | |
942 | } | |
943 | ||
944 | /* Remove REG_EQUAL note after simplification. */ | |
945 | if (note_src) | |
946 | remove_note (jump, note); | |
947 | } | |
948 | ||
949 | #ifdef HAVE_cc0 | |
950 | /* Delete the cc0 setter. */ | |
951 | if (setcc != NULL && CC0_P (SET_DEST (single_set (setcc)))) | |
952 | delete_insn (setcc); | |
953 | #endif | |
954 | ||
955 | global_const_prop_count++; | |
956 | if (dump_file != NULL) | |
957 | { | |
958 | fprintf (dump_file, | |
63b7075c | 959 | "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with" |
960 | "constant ", REGNO (from), INSN_UID (jump)); | |
07abdb66 | 961 | print_rtl (dump_file, src); |
962 | fprintf (dump_file, "\n"); | |
963 | } | |
964 | purge_dead_edges (bb); | |
965 | ||
966 | /* If a conditional jump has been changed into unconditional jump, remove | |
967 | the jump and make the edge fallthru - this is always called in | |
968 | cfglayout mode. */ | |
969 | if (new_rtx != pc_rtx && simplejump_p (jump)) | |
970 | { | |
971 | edge e; | |
972 | edge_iterator ei; | |
973 | ||
c8a32de3 | 974 | FOR_EACH_EDGE (e, ei, bb->succs) |
07abdb66 | 975 | if (e->dest != EXIT_BLOCK_PTR |
976 | && BB_HEAD (e->dest) == JUMP_LABEL (jump)) | |
977 | { | |
978 | e->flags |= EDGE_FALLTHRU; | |
979 | break; | |
980 | } | |
981 | delete_insn (jump); | |
982 | } | |
983 | ||
984 | return 1; | |
985 | } | |
986 | ||
63b7075c | 987 | /* Subroutine of cprop_insn that tries to propagate constants. FROM is what |
988 | we will try to replace, SRC is the constant we will try to substitute for | |
989 | it and INSN is the instruction where this will be happening. */ | |
990 | ||
991 | static int | |
992 | constprop_register (rtx from, rtx src, rtx insn) | |
07abdb66 | 993 | { |
994 | rtx sset; | |
995 | ||
996 | /* Check for reg or cc0 setting instructions followed by | |
997 | conditional branch instructions first. */ | |
998 | if ((sset = single_set (insn)) != NULL | |
999 | && NEXT_INSN (insn) | |
1000 | && any_condjump_p (NEXT_INSN (insn)) && onlyjump_p (NEXT_INSN (insn))) | |
1001 | { | |
1002 | rtx dest = SET_DEST (sset); | |
1003 | if ((REG_P (dest) || CC0_P (dest)) | |
63b7075c | 1004 | && cprop_jump (BLOCK_FOR_INSN (insn), insn, NEXT_INSN (insn), |
1005 | from, src)) | |
07abdb66 | 1006 | return 1; |
1007 | } | |
1008 | ||
1009 | /* Handle normal insns next. */ | |
63b7075c | 1010 | if (NONJUMP_INSN_P (insn) && try_replace_reg (from, src, insn)) |
07abdb66 | 1011 | return 1; |
1012 | ||
1013 | /* Try to propagate a CONST_INT into a conditional jump. | |
1014 | We're pretty specific about what we will handle in this | |
1015 | code, we can extend this as necessary over time. | |
1016 | ||
1017 | Right now the insn in question must look like | |
1018 | (set (pc) (if_then_else ...)) */ | |
1019 | else if (any_condjump_p (insn) && onlyjump_p (insn)) | |
63b7075c | 1020 | return cprop_jump (BLOCK_FOR_INSN (insn), NULL, insn, from, src); |
07abdb66 | 1021 | return 0; |
1022 | } | |
1023 | ||
1024 | /* Perform constant and copy propagation on INSN. | |
63b7075c | 1025 | Return nonzero if a change was made. */ |
07abdb66 | 1026 | |
1027 | static int | |
1028 | cprop_insn (rtx insn) | |
1029 | { | |
748fd717 | 1030 | unsigned i; |
1031 | int changed = 0, changed_this_round; | |
07abdb66 | 1032 | rtx note; |
1033 | ||
748fd717 | 1034 | retry: |
1035 | changed_this_round = 0; | |
07abdb66 | 1036 | reg_use_count = 0; |
1037 | note_uses (&PATTERN (insn), find_used_regs, NULL); | |
1038 | ||
07abdb66 | 1039 | /* We may win even when propagating constants into notes. */ |
202325b0 | 1040 | note = find_reg_equal_equiv_note (insn); |
07abdb66 | 1041 | if (note) |
1042 | find_used_regs (&XEXP (note, 0), NULL); | |
1043 | ||
748fd717 | 1044 | for (i = 0; i < reg_use_count; i++) |
07abdb66 | 1045 | { |
748fd717 | 1046 | rtx reg_used = reg_use_table[i]; |
1047 | unsigned int regno = REGNO (reg_used); | |
202325b0 | 1048 | rtx src; |
07abdb66 | 1049 | struct expr *set; |
1050 | ||
1051 | /* If the register has already been set in this block, there's | |
1052 | nothing we can do. */ | |
748fd717 | 1053 | if (! reg_not_set_p (reg_used, insn)) |
07abdb66 | 1054 | continue; |
1055 | ||
1056 | /* Find an assignment that sets reg_used and is available | |
1057 | at the start of the block. */ | |
1058 | set = find_avail_set (regno, insn); | |
1059 | if (! set) | |
1060 | continue; | |
1061 | ||
202325b0 | 1062 | src = set->src; |
07abdb66 | 1063 | |
1064 | /* Constant propagation. */ | |
540960d1 | 1065 | if (cprop_constant_p (src)) |
07abdb66 | 1066 | { |
63b7075c | 1067 | if (constprop_register (reg_used, src, insn)) |
07abdb66 | 1068 | { |
748fd717 | 1069 | changed_this_round = changed = 1; |
07abdb66 | 1070 | global_const_prop_count++; |
1071 | if (dump_file != NULL) | |
1072 | { | |
63b7075c | 1073 | fprintf (dump_file, |
1074 | "GLOBAL CONST-PROP: Replacing reg %d in ", regno); | |
1075 | fprintf (dump_file, "insn %d with constant ", | |
1076 | INSN_UID (insn)); | |
07abdb66 | 1077 | print_rtl (dump_file, src); |
1078 | fprintf (dump_file, "\n"); | |
1079 | } | |
1080 | if (INSN_DELETED_P (insn)) | |
1081 | return 1; | |
1082 | } | |
1083 | } | |
1084 | else if (REG_P (src) | |
1085 | && REGNO (src) >= FIRST_PSEUDO_REGISTER | |
1086 | && REGNO (src) != regno) | |
1087 | { | |
748fd717 | 1088 | if (try_replace_reg (reg_used, src, insn)) |
07abdb66 | 1089 | { |
748fd717 | 1090 | changed_this_round = changed = 1; |
07abdb66 | 1091 | global_copy_prop_count++; |
1092 | if (dump_file != NULL) | |
1093 | { | |
63b7075c | 1094 | fprintf (dump_file, |
1095 | "GLOBAL COPY-PROP: Replacing reg %d in insn %d", | |
07abdb66 | 1096 | regno, INSN_UID (insn)); |
1097 | fprintf (dump_file, " with reg %d\n", REGNO (src)); | |
1098 | } | |
1099 | ||
1100 | /* The original insn setting reg_used may or may not now be | |
202325b0 | 1101 | deletable. We leave the deletion to DCE. */ |
07abdb66 | 1102 | /* FIXME: If it turns out that the insn isn't deletable, |
1103 | then we may have unnecessarily extended register lifetimes | |
1104 | and made things worse. */ | |
1105 | } | |
1106 | } | |
748fd717 | 1107 | |
1108 | /* If try_replace_reg simplified the insn, the regs found | |
1109 | by find_used_regs may not be valid anymore. Start over. */ | |
1110 | if (changed_this_round) | |
1111 | goto retry; | |
07abdb66 | 1112 | } |
1113 | ||
1114 | if (changed && DEBUG_INSN_P (insn)) | |
1115 | return 0; | |
1116 | ||
1117 | return changed; | |
1118 | } | |
1119 | ||
1120 | /* Like find_used_regs, but avoid recording uses that appear in | |
1121 | input-output contexts such as zero_extract or pre_dec. This | |
1122 | restricts the cases we consider to those for which local cprop | |
1123 | can legitimately make replacements. */ | |
1124 | ||
1125 | static void | |
1126 | local_cprop_find_used_regs (rtx *xptr, void *data) | |
1127 | { | |
1128 | rtx x = *xptr; | |
1129 | ||
1130 | if (x == 0) | |
1131 | return; | |
1132 | ||
1133 | switch (GET_CODE (x)) | |
1134 | { | |
1135 | case ZERO_EXTRACT: | |
1136 | case SIGN_EXTRACT: | |
1137 | case STRICT_LOW_PART: | |
1138 | return; | |
1139 | ||
1140 | case PRE_DEC: | |
1141 | case PRE_INC: | |
1142 | case POST_DEC: | |
1143 | case POST_INC: | |
1144 | case PRE_MODIFY: | |
1145 | case POST_MODIFY: | |
1146 | /* Can only legitimately appear this early in the context of | |
1147 | stack pushes for function arguments, but handle all of the | |
1148 | codes nonetheless. */ | |
1149 | return; | |
1150 | ||
1151 | case SUBREG: | |
1152 | /* Setting a subreg of a register larger than word_mode leaves | |
1153 | the non-written words unchanged. */ | |
1154 | if (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x))) > BITS_PER_WORD) | |
1155 | return; | |
1156 | break; | |
1157 | ||
1158 | default: | |
1159 | break; | |
1160 | } | |
1161 | ||
1162 | find_used_regs (xptr, data); | |
1163 | } | |
1164 | ||
1165 | /* Try to perform local const/copy propagation on X in INSN. */ | |
1166 | ||
1167 | static bool | |
1168 | do_local_cprop (rtx x, rtx insn) | |
1169 | { | |
1170 | rtx newreg = NULL, newcnst = NULL; | |
1171 | ||
1172 | /* Rule out USE instructions and ASM statements as we don't want to | |
1173 | change the hard registers mentioned. */ | |
1174 | if (REG_P (x) | |
1175 | && (REGNO (x) >= FIRST_PSEUDO_REGISTER | |
1176 | || (GET_CODE (PATTERN (insn)) != USE | |
1177 | && asm_noperands (PATTERN (insn)) < 0))) | |
1178 | { | |
1179 | cselib_val *val = cselib_lookup (x, GET_MODE (x), 0, VOIDmode); | |
1180 | struct elt_loc_list *l; | |
1181 | ||
1182 | if (!val) | |
1183 | return false; | |
1184 | for (l = val->locs; l; l = l->next) | |
1185 | { | |
1186 | rtx this_rtx = l->loc; | |
1187 | rtx note; | |
1188 | ||
540960d1 | 1189 | if (cprop_constant_p (this_rtx)) |
07abdb66 | 1190 | newcnst = this_rtx; |
1191 | if (REG_P (this_rtx) && REGNO (this_rtx) >= FIRST_PSEUDO_REGISTER | |
1192 | /* Don't copy propagate if it has attached REG_EQUIV note. | |
1193 | At this point this only function parameters should have | |
1194 | REG_EQUIV notes and if the argument slot is used somewhere | |
1195 | explicitly, it means address of parameter has been taken, | |
1196 | so we should not extend the lifetime of the pseudo. */ | |
1197 | && (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX)) | |
1198 | || ! MEM_P (XEXP (note, 0)))) | |
1199 | newreg = this_rtx; | |
1200 | } | |
63b7075c | 1201 | if (newcnst && constprop_register (x, newcnst, insn)) |
07abdb66 | 1202 | { |
1203 | if (dump_file != NULL) | |
1204 | { | |
1205 | fprintf (dump_file, "LOCAL CONST-PROP: Replacing reg %d in ", | |
1206 | REGNO (x)); | |
1207 | fprintf (dump_file, "insn %d with constant ", | |
1208 | INSN_UID (insn)); | |
1209 | print_rtl (dump_file, newcnst); | |
1210 | fprintf (dump_file, "\n"); | |
1211 | } | |
1212 | local_const_prop_count++; | |
1213 | return true; | |
1214 | } | |
1215 | else if (newreg && newreg != x && try_replace_reg (x, newreg, insn)) | |
1216 | { | |
1217 | if (dump_file != NULL) | |
1218 | { | |
1219 | fprintf (dump_file, | |
1220 | "LOCAL COPY-PROP: Replacing reg %d in insn %d", | |
1221 | REGNO (x), INSN_UID (insn)); | |
1222 | fprintf (dump_file, " with reg %d\n", REGNO (newreg)); | |
1223 | } | |
1224 | local_copy_prop_count++; | |
1225 | return true; | |
1226 | } | |
1227 | } | |
1228 | return false; | |
1229 | } | |
1230 | ||
1231 | /* Do local const/copy propagation (i.e. within each basic block). */ | |
1232 | ||
1233 | static int | |
1234 | local_cprop_pass (void) | |
1235 | { | |
1236 | basic_block bb; | |
1237 | rtx insn; | |
07abdb66 | 1238 | bool changed = false; |
748fd717 | 1239 | unsigned i; |
07abdb66 | 1240 | |
1241 | cselib_init (0); | |
1242 | FOR_EACH_BB (bb) | |
1243 | { | |
1244 | FOR_BB_INSNS (bb, insn) | |
1245 | { | |
1246 | if (INSN_P (insn)) | |
1247 | { | |
1248 | rtx note = find_reg_equal_equiv_note (insn); | |
1249 | do | |
1250 | { | |
1251 | reg_use_count = 0; | |
1252 | note_uses (&PATTERN (insn), local_cprop_find_used_regs, | |
1253 | NULL); | |
1254 | if (note) | |
1255 | local_cprop_find_used_regs (&XEXP (note, 0), NULL); | |
1256 | ||
748fd717 | 1257 | for (i = 0; i < reg_use_count; i++) |
07abdb66 | 1258 | { |
748fd717 | 1259 | if (do_local_cprop (reg_use_table[i], insn)) |
07abdb66 | 1260 | { |
4446c883 | 1261 | if (!DEBUG_INSN_P (insn)) |
1262 | changed = true; | |
07abdb66 | 1263 | break; |
1264 | } | |
1265 | } | |
1266 | if (INSN_DELETED_P (insn)) | |
1267 | break; | |
1268 | } | |
748fd717 | 1269 | while (i < reg_use_count); |
07abdb66 | 1270 | } |
1271 | cselib_process_insn (insn); | |
1272 | } | |
1273 | ||
1274 | /* Forget everything at the end of a basic block. */ | |
1275 | cselib_clear_table (); | |
1276 | } | |
1277 | ||
1278 | cselib_finish (); | |
1279 | ||
1280 | return changed; | |
1281 | } | |
1282 | ||
1283 | /* Similar to get_condition, only the resulting condition must be | |
1284 | valid at JUMP, instead of at EARLIEST. | |
1285 | ||
1286 | This differs from noce_get_condition in ifcvt.c in that we prefer not to | |
1287 | settle for the condition variable in the jump instruction being integral. | |
1288 | We prefer to be able to record the value of a user variable, rather than | |
1289 | the value of a temporary used in a condition. This could be solved by | |
1290 | recording the value of *every* register scanned by canonicalize_condition, | |
1291 | but this would require some code reorganization. */ | |
1292 | ||
1293 | rtx | |
1294 | fis_get_condition (rtx jump) | |
1295 | { | |
1296 | return get_condition (jump, NULL, false, true); | |
1297 | } | |
1298 | ||
971ce6d5 | 1299 | /* Check the comparison COND to see if we can safely form an implicit |
1300 | set from it. */ | |
07abdb66 | 1301 | |
1302 | static bool | |
1303 | implicit_set_cond_p (const_rtx cond) | |
1304 | { | |
971ce6d5 | 1305 | enum machine_mode mode; |
1306 | rtx cst; | |
1307 | ||
1308 | /* COND must be either an EQ or NE comparison. */ | |
1309 | if (GET_CODE (cond) != EQ && GET_CODE (cond) != NE) | |
1310 | return false; | |
1311 | ||
1312 | /* The first operand of COND must be a pseudo-reg. */ | |
1313 | if (! REG_P (XEXP (cond, 0)) | |
1314 | || HARD_REGISTER_P (XEXP (cond, 0))) | |
1315 | return false; | |
1316 | ||
1317 | /* The second operand of COND must be a suitable constant. */ | |
1318 | mode = GET_MODE (XEXP (cond, 0)); | |
1319 | cst = XEXP (cond, 1); | |
07abdb66 | 1320 | |
1321 | /* We can't perform this optimization if either operand might be or might | |
1322 | contain a signed zero. */ | |
1323 | if (HONOR_SIGNED_ZEROS (mode)) | |
1324 | { | |
1325 | /* It is sufficient to check if CST is or contains a zero. We must | |
1326 | handle float, complex, and vector. If any subpart is a zero, then | |
1327 | the optimization can't be performed. */ | |
1328 | /* ??? The complex and vector checks are not implemented yet. We just | |
1329 | always return zero for them. */ | |
78f1962f | 1330 | if (CONST_DOUBLE_AS_FLOAT_P (cst)) |
07abdb66 | 1331 | { |
1332 | REAL_VALUE_TYPE d; | |
1333 | REAL_VALUE_FROM_CONST_DOUBLE (d, cst); | |
1334 | if (REAL_VALUES_EQUAL (d, dconst0)) | |
1335 | return 0; | |
1336 | } | |
1337 | else | |
1338 | return 0; | |
1339 | } | |
1340 | ||
540960d1 | 1341 | return cprop_constant_p (cst); |
07abdb66 | 1342 | } |
1343 | ||
1344 | /* Find the implicit sets of a function. An "implicit set" is a constraint | |
1345 | on the value of a variable, implied by a conditional jump. For example, | |
1346 | following "if (x == 2)", the then branch may be optimized as though the | |
1347 | conditional performed an "explicit set", in this example, "x = 2". This | |
1348 | function records the set patterns that are implicit at the start of each | |
1349 | basic block. | |
1350 | ||
971ce6d5 | 1351 | If an implicit set is found but the set is implicit on a critical edge, |
1352 | this critical edge is split. | |
07abdb66 | 1353 | |
971ce6d5 | 1354 | Return true if the CFG was modified, false otherwise. */ |
1355 | ||
1356 | static bool | |
07abdb66 | 1357 | find_implicit_sets (void) |
1358 | { | |
1359 | basic_block bb, dest; | |
07abdb66 | 1360 | rtx cond, new_rtx; |
971ce6d5 | 1361 | unsigned int count = 0; |
1362 | bool edges_split = false; | |
1363 | size_t implicit_sets_size = last_basic_block + 10; | |
1364 | ||
1365 | implicit_sets = XCNEWVEC (rtx, implicit_sets_size); | |
07abdb66 | 1366 | |
07abdb66 | 1367 | FOR_EACH_BB (bb) |
971ce6d5 | 1368 | { |
1369 | /* Check for more than one successor. */ | |
2f7c1e7a | 1370 | if (EDGE_COUNT (bb->succs) <= 1) |
971ce6d5 | 1371 | continue; |
07abdb66 | 1372 | |
971ce6d5 | 1373 | cond = fis_get_condition (BB_END (bb)); |
07abdb66 | 1374 | |
971ce6d5 | 1375 | /* If no condition is found or if it isn't of a suitable form, |
1376 | ignore it. */ | |
1377 | if (! cond || ! implicit_set_cond_p (cond)) | |
1378 | continue; | |
1379 | ||
1380 | dest = GET_CODE (cond) == EQ | |
1381 | ? BRANCH_EDGE (bb)->dest : FALLTHRU_EDGE (bb)->dest; | |
1382 | ||
1383 | /* If DEST doesn't go anywhere, ignore it. */ | |
1384 | if (! dest || dest == EXIT_BLOCK_PTR) | |
1385 | continue; | |
1386 | ||
1387 | /* We have found a suitable implicit set. Try to record it now as | |
1388 | a SET in DEST. If DEST has more than one predecessor, the edge | |
1389 | between BB and DEST is a critical edge and we must split it, | |
1390 | because we can only record one implicit set per DEST basic block. */ | |
1391 | if (! single_pred_p (dest)) | |
1392 | { | |
1393 | dest = split_edge (find_edge (bb, dest)); | |
1394 | edges_split = true; | |
1395 | } | |
1396 | ||
1397 | if (implicit_sets_size <= (size_t) dest->index) | |
1398 | { | |
1399 | size_t old_implicit_sets_size = implicit_sets_size; | |
1400 | implicit_sets_size *= 2; | |
1401 | implicit_sets = XRESIZEVEC (rtx, implicit_sets, implicit_sets_size); | |
1402 | memset (implicit_sets + old_implicit_sets_size, 0, | |
1403 | (implicit_sets_size - old_implicit_sets_size) * sizeof (rtx)); | |
07abdb66 | 1404 | } |
1405 | ||
971ce6d5 | 1406 | new_rtx = gen_rtx_SET (VOIDmode, XEXP (cond, 0), |
1407 | XEXP (cond, 1)); | |
1408 | implicit_sets[dest->index] = new_rtx; | |
1409 | if (dump_file) | |
1410 | { | |
1411 | fprintf(dump_file, "Implicit set of reg %d in ", | |
1412 | REGNO (XEXP (cond, 0))); | |
1413 | fprintf(dump_file, "basic block %d\n", dest->index); | |
1414 | } | |
1415 | count++; | |
1416 | } | |
1417 | ||
07abdb66 | 1418 | if (dump_file) |
1419 | fprintf (dump_file, "Found %d implicit sets\n", count); | |
971ce6d5 | 1420 | |
1421 | /* Confess our sins. */ | |
1422 | return edges_split; | |
07abdb66 | 1423 | } |
1424 | ||
1425 | /* Bypass conditional jumps. */ | |
1426 | ||
1427 | /* The value of last_basic_block at the beginning of the jump_bypass | |
1428 | pass. The use of redirect_edge_and_branch_force may introduce new | |
1429 | basic blocks, but the data flow analysis is only valid for basic | |
1430 | block indices less than bypass_last_basic_block. */ | |
1431 | ||
1432 | static int bypass_last_basic_block; | |
1433 | ||
1434 | /* Find a set of REGNO to a constant that is available at the end of basic | |
63b7075c | 1435 | block BB. Return NULL if no such set is found. Based heavily upon |
07abdb66 | 1436 | find_avail_set. */ |
1437 | ||
1438 | static struct expr * | |
1439 | find_bypass_set (int regno, int bb) | |
1440 | { | |
1441 | struct expr *result = 0; | |
1442 | ||
1443 | for (;;) | |
1444 | { | |
1445 | rtx src; | |
1446 | struct expr *set = lookup_set (regno, &set_hash_table); | |
1447 | ||
1448 | while (set) | |
1449 | { | |
1450 | if (TEST_BIT (cprop_avout[bb], set->bitmap_index)) | |
1451 | break; | |
1452 | set = next_set (regno, set); | |
1453 | } | |
1454 | ||
1455 | if (set == 0) | |
1456 | break; | |
1457 | ||
202325b0 | 1458 | src = set->src; |
540960d1 | 1459 | if (cprop_constant_p (src)) |
07abdb66 | 1460 | result = set; |
1461 | ||
1462 | if (! REG_P (src)) | |
1463 | break; | |
1464 | ||
1465 | regno = REGNO (src); | |
1466 | } | |
1467 | return result; | |
1468 | } | |
1469 | ||
07abdb66 | 1470 | /* Subroutine of bypass_block that checks whether a pseudo is killed by |
1471 | any of the instructions inserted on an edge. Jump bypassing places | |
1472 | condition code setters on CFG edges using insert_insn_on_edge. This | |
1473 | function is required to check that our data flow analysis is still | |
1474 | valid prior to commit_edge_insertions. */ | |
1475 | ||
1476 | static bool | |
1477 | reg_killed_on_edge (const_rtx reg, const_edge e) | |
1478 | { | |
1479 | rtx insn; | |
1480 | ||
1481 | for (insn = e->insns.r; insn; insn = NEXT_INSN (insn)) | |
1482 | if (INSN_P (insn) && reg_set_p (reg, insn)) | |
1483 | return true; | |
1484 | ||
1485 | return false; | |
1486 | } | |
1487 | ||
1488 | /* Subroutine of bypass_conditional_jumps that attempts to bypass the given | |
1489 | basic block BB which has more than one predecessor. If not NULL, SETCC | |
1490 | is the first instruction of BB, which is immediately followed by JUMP_INSN | |
1491 | JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB. | |
1492 | Returns nonzero if a change was made. | |
1493 | ||
1494 | During the jump bypassing pass, we may place copies of SETCC instructions | |
1495 | on CFG edges. The following routine must be careful to pay attention to | |
1496 | these inserted insns when performing its transformations. */ | |
1497 | ||
1498 | static int | |
1499 | bypass_block (basic_block bb, rtx setcc, rtx jump) | |
1500 | { | |
1501 | rtx insn, note; | |
1502 | edge e, edest; | |
748fd717 | 1503 | int change; |
07abdb66 | 1504 | int may_be_loop_header; |
1505 | unsigned removed_p; | |
748fd717 | 1506 | unsigned i; |
07abdb66 | 1507 | edge_iterator ei; |
1508 | ||
1509 | insn = (setcc != NULL) ? setcc : jump; | |
1510 | ||
1511 | /* Determine set of register uses in INSN. */ | |
1512 | reg_use_count = 0; | |
1513 | note_uses (&PATTERN (insn), find_used_regs, NULL); | |
1514 | note = find_reg_equal_equiv_note (insn); | |
1515 | if (note) | |
1516 | find_used_regs (&XEXP (note, 0), NULL); | |
1517 | ||
1518 | may_be_loop_header = false; | |
1519 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1520 | if (e->flags & EDGE_DFS_BACK) | |
1521 | { | |
1522 | may_be_loop_header = true; | |
1523 | break; | |
1524 | } | |
1525 | ||
1526 | change = 0; | |
1527 | for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); ) | |
1528 | { | |
1529 | removed_p = 0; | |
1530 | ||
1531 | if (e->flags & EDGE_COMPLEX) | |
1532 | { | |
1533 | ei_next (&ei); | |
1534 | continue; | |
1535 | } | |
1536 | ||
1537 | /* We can't redirect edges from new basic blocks. */ | |
1538 | if (e->src->index >= bypass_last_basic_block) | |
1539 | { | |
1540 | ei_next (&ei); | |
1541 | continue; | |
1542 | } | |
1543 | ||
1544 | /* The irreducible loops created by redirecting of edges entering the | |
63b7075c | 1545 | loop from outside would decrease effectiveness of some of the |
1546 | following optimizations, so prevent this. */ | |
07abdb66 | 1547 | if (may_be_loop_header |
1548 | && !(e->flags & EDGE_DFS_BACK)) | |
1549 | { | |
1550 | ei_next (&ei); | |
1551 | continue; | |
1552 | } | |
1553 | ||
1554 | for (i = 0; i < reg_use_count; i++) | |
1555 | { | |
748fd717 | 1556 | rtx reg_used = reg_use_table[i]; |
1557 | unsigned int regno = REGNO (reg_used); | |
07abdb66 | 1558 | basic_block dest, old_dest; |
1559 | struct expr *set; | |
1560 | rtx src, new_rtx; | |
1561 | ||
1562 | set = find_bypass_set (regno, e->src->index); | |
1563 | ||
1564 | if (! set) | |
1565 | continue; | |
1566 | ||
1567 | /* Check the data flow is valid after edge insertions. */ | |
748fd717 | 1568 | if (e->insns.r && reg_killed_on_edge (reg_used, e)) |
07abdb66 | 1569 | continue; |
1570 | ||
1571 | src = SET_SRC (pc_set (jump)); | |
1572 | ||
1573 | if (setcc != NULL) | |
1574 | src = simplify_replace_rtx (src, | |
1575 | SET_DEST (PATTERN (setcc)), | |
1576 | SET_SRC (PATTERN (setcc))); | |
1577 | ||
748fd717 | 1578 | new_rtx = simplify_replace_rtx (src, reg_used, set->src); |
07abdb66 | 1579 | |
1580 | /* Jump bypassing may have already placed instructions on | |
1581 | edges of the CFG. We can't bypass an outgoing edge that | |
1582 | has instructions associated with it, as these insns won't | |
1583 | get executed if the incoming edge is redirected. */ | |
07abdb66 | 1584 | if (new_rtx == pc_rtx) |
1585 | { | |
1586 | edest = FALLTHRU_EDGE (bb); | |
1587 | dest = edest->insns.r ? NULL : edest->dest; | |
1588 | } | |
1589 | else if (GET_CODE (new_rtx) == LABEL_REF) | |
1590 | { | |
1591 | dest = BLOCK_FOR_INSN (XEXP (new_rtx, 0)); | |
1592 | /* Don't bypass edges containing instructions. */ | |
1593 | edest = find_edge (bb, dest); | |
1594 | if (edest && edest->insns.r) | |
1595 | dest = NULL; | |
1596 | } | |
1597 | else | |
1598 | dest = NULL; | |
1599 | ||
1600 | /* Avoid unification of the edge with other edges from original | |
1601 | branch. We would end up emitting the instruction on "both" | |
1602 | edges. */ | |
07abdb66 | 1603 | if (dest && setcc && !CC0_P (SET_DEST (PATTERN (setcc))) |
1604 | && find_edge (e->src, dest)) | |
1605 | dest = NULL; | |
1606 | ||
1607 | old_dest = e->dest; | |
1608 | if (dest != NULL | |
1609 | && dest != old_dest | |
1610 | && dest != EXIT_BLOCK_PTR) | |
1611 | { | |
79f958cb | 1612 | if (current_loops != NULL |
1613 | && e->src->loop_father->latch == e->src) | |
1614 | { | |
1615 | /* ??? Now we are creating (or may create) a loop | |
1616 | with multiple entries. Simply mark it for | |
1617 | removal. Alternatively we could not do this | |
1618 | threading. */ | |
1619 | e->src->loop_father->header = NULL; | |
1620 | e->src->loop_father->latch = NULL; | |
1621 | } | |
1622 | ||
07abdb66 | 1623 | redirect_edge_and_branch_force (e, dest); |
1624 | ||
1625 | /* Copy the register setter to the redirected edge. | |
1626 | Don't copy CC0 setters, as CC0 is dead after jump. */ | |
1627 | if (setcc) | |
1628 | { | |
1629 | rtx pat = PATTERN (setcc); | |
1630 | if (!CC0_P (SET_DEST (pat))) | |
1631 | insert_insn_on_edge (copy_insn (pat), e); | |
1632 | } | |
1633 | ||
1634 | if (dump_file != NULL) | |
1635 | { | |
1636 | fprintf (dump_file, "JUMP-BYPASS: Proved reg %d " | |
1637 | "in jump_insn %d equals constant ", | |
1638 | regno, INSN_UID (jump)); | |
202325b0 | 1639 | print_rtl (dump_file, set->src); |
07abdb66 | 1640 | fprintf (dump_file, "\nBypass edge from %d->%d to %d\n", |
1641 | e->src->index, old_dest->index, dest->index); | |
1642 | } | |
1643 | change = 1; | |
1644 | removed_p = 1; | |
1645 | break; | |
1646 | } | |
1647 | } | |
1648 | if (!removed_p) | |
1649 | ei_next (&ei); | |
1650 | } | |
1651 | return change; | |
1652 | } | |
1653 | ||
1654 | /* Find basic blocks with more than one predecessor that only contain a | |
1655 | single conditional jump. If the result of the comparison is known at | |
1656 | compile-time from any incoming edge, redirect that edge to the | |
63b7075c | 1657 | appropriate target. Return nonzero if a change was made. |
07abdb66 | 1658 | |
1659 | This function is now mis-named, because we also handle indirect jumps. */ | |
1660 | ||
1661 | static int | |
1662 | bypass_conditional_jumps (void) | |
1663 | { | |
1664 | basic_block bb; | |
1665 | int changed; | |
1666 | rtx setcc; | |
1667 | rtx insn; | |
1668 | rtx dest; | |
1669 | ||
1670 | /* Note we start at block 1. */ | |
1671 | if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR) | |
1672 | return 0; | |
1673 | ||
1674 | bypass_last_basic_block = last_basic_block; | |
1675 | mark_dfs_back_edges (); | |
1676 | ||
1677 | changed = 0; | |
1678 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, | |
1679 | EXIT_BLOCK_PTR, next_bb) | |
1680 | { | |
1681 | /* Check for more than one predecessor. */ | |
1682 | if (!single_pred_p (bb)) | |
1683 | { | |
1684 | setcc = NULL_RTX; | |
1685 | FOR_BB_INSNS (bb, insn) | |
1686 | if (DEBUG_INSN_P (insn)) | |
1687 | continue; | |
1688 | else if (NONJUMP_INSN_P (insn)) | |
1689 | { | |
1690 | if (setcc) | |
1691 | break; | |
1692 | if (GET_CODE (PATTERN (insn)) != SET) | |
1693 | break; | |
1694 | ||
1695 | dest = SET_DEST (PATTERN (insn)); | |
1696 | if (REG_P (dest) || CC0_P (dest)) | |
1697 | setcc = insn; | |
1698 | else | |
1699 | break; | |
1700 | } | |
1701 | else if (JUMP_P (insn)) | |
1702 | { | |
1703 | if ((any_condjump_p (insn) || computed_jump_p (insn)) | |
1704 | && onlyjump_p (insn)) | |
1705 | changed |= bypass_block (bb, setcc, insn); | |
1706 | break; | |
1707 | } | |
1708 | else if (INSN_P (insn)) | |
1709 | break; | |
1710 | } | |
1711 | } | |
1712 | ||
1713 | /* If we bypassed any register setting insns, we inserted a | |
1714 | copy on the redirected edge. These need to be committed. */ | |
1715 | if (changed) | |
1716 | commit_edge_insertions (); | |
1717 | ||
1718 | return changed; | |
1719 | } | |
1720 | \f | |
63b7075c | 1721 | /* Return true if the graph is too expensive to optimize. PASS is the |
07abdb66 | 1722 | optimization about to be performed. */ |
1723 | ||
1724 | static bool | |
1725 | is_too_expensive (const char *pass) | |
1726 | { | |
1727 | /* Trying to perform global optimizations on flow graphs which have | |
1728 | a high connectivity will take a long time and is unlikely to be | |
1729 | particularly useful. | |
1730 | ||
1731 | In normal circumstances a cfg should have about twice as many | |
1732 | edges as blocks. But we do not want to punish small functions | |
1733 | which have a couple switch statements. Rather than simply | |
1734 | threshold the number of blocks, uses something with a more | |
1735 | graceful degradation. */ | |
1736 | if (n_edges > 20000 + n_basic_blocks * 4) | |
1737 | { | |
1738 | warning (OPT_Wdisabled_optimization, | |
1739 | "%s: %d basic blocks and %d edges/basic block", | |
1740 | pass, n_basic_blocks, n_edges / n_basic_blocks); | |
1741 | ||
1742 | return true; | |
1743 | } | |
1744 | ||
1745 | /* If allocating memory for the cprop bitmap would take up too much | |
1746 | storage it's better just to disable the optimization. */ | |
1747 | if ((n_basic_blocks | |
1748 | * SBITMAP_SET_SIZE (max_reg_num ()) | |
1749 | * sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY) | |
1750 | { | |
1751 | warning (OPT_Wdisabled_optimization, | |
1752 | "%s: %d basic blocks and %d registers", | |
1753 | pass, n_basic_blocks, max_reg_num ()); | |
1754 | ||
1755 | return true; | |
1756 | } | |
1757 | ||
1758 | return false; | |
1759 | } | |
07abdb66 | 1760 | \f |
1761 | /* Main function for the CPROP pass. */ | |
1762 | ||
1763 | static int | |
1764 | one_cprop_pass (void) | |
1765 | { | |
522983c2 | 1766 | int i; |
07abdb66 | 1767 | int changed = 0; |
1768 | ||
1769 | /* Return if there's nothing to do, or it is too expensive. */ | |
1770 | if (n_basic_blocks <= NUM_FIXED_BLOCKS + 1 | |
1771 | || is_too_expensive (_ ("const/copy propagation disabled"))) | |
1772 | return 0; | |
1773 | ||
1774 | global_const_prop_count = local_const_prop_count = 0; | |
1775 | global_copy_prop_count = local_copy_prop_count = 0; | |
1776 | ||
1777 | bytes_used = 0; | |
540960d1 | 1778 | gcc_obstack_init (&cprop_obstack); |
07abdb66 | 1779 | |
1780 | /* Do a local const/copy propagation pass first. The global pass | |
1781 | only handles global opportunities. | |
1782 | If the local pass changes something, remove any unreachable blocks | |
1783 | because the CPROP global dataflow analysis may get into infinite | |
1784 | loops for CFGs with unreachable blocks. | |
1785 | ||
1786 | FIXME: This local pass should not be necessary after CSE (but for | |
1787 | some reason it still is). It is also (proven) not necessary | |
1788 | to run the local pass right after FWPWOP. | |
1789 | ||
1790 | FIXME: The global analysis would not get into infinite loops if it | |
1791 | would use the DF solver (via df_simple_dataflow) instead of | |
1792 | the solver implemented in this file. */ | |
540960d1 | 1793 | changed |= local_cprop_pass (); |
1794 | if (changed) | |
971ce6d5 | 1795 | delete_unreachable_blocks (); |
1796 | ||
1797 | /* Determine implicit sets. This may change the CFG (split critical | |
1798 | edges if that exposes an implicit set). | |
1799 | Note that find_implicit_sets() does not rely on up-to-date DF caches | |
1800 | so that we do not have to re-run df_analyze() even if local CPROP | |
1801 | changed something. | |
1802 | ??? This could run earlier so that any uncovered implicit sets | |
1803 | sets could be exploited in local_cprop_pass() also. Later. */ | |
1804 | changed |= find_implicit_sets (); | |
1805 | ||
1806 | /* If local_cprop_pass() or find_implicit_sets() changed something, | |
1807 | run df_analyze() to bring all insn caches up-to-date, and to take | |
1808 | new basic blocks from edge splitting on the DF radar. | |
1809 | NB: This also runs the fast DCE pass, because execute_rtl_cprop | |
1810 | sets DF_LR_RUN_DCE. */ | |
1811 | if (changed) | |
1812 | df_analyze (); | |
07abdb66 | 1813 | |
522983c2 | 1814 | /* Initialize implicit_set_indexes array. */ |
1815 | implicit_set_indexes = XNEWVEC (int, last_basic_block); | |
1816 | for (i = 0; i < last_basic_block; i++) | |
1817 | implicit_set_indexes[i] = -1; | |
1818 | ||
07abdb66 | 1819 | alloc_hash_table (&set_hash_table); |
1820 | compute_hash_table (&set_hash_table); | |
1821 | ||
1822 | /* Free implicit_sets before peak usage. */ | |
1823 | free (implicit_sets); | |
1824 | implicit_sets = NULL; | |
1825 | ||
1826 | if (dump_file) | |
1827 | dump_hash_table (dump_file, "SET", &set_hash_table); | |
1828 | if (set_hash_table.n_elems > 0) | |
1829 | { | |
1830 | basic_block bb; | |
1831 | rtx insn; | |
1832 | ||
1833 | alloc_cprop_mem (last_basic_block, set_hash_table.n_elems); | |
1834 | compute_cprop_data (); | |
1835 | ||
522983c2 | 1836 | free (implicit_set_indexes); |
1837 | implicit_set_indexes = NULL; | |
1838 | ||
540960d1 | 1839 | /* Allocate vars to track sets of regs. */ |
1840 | reg_set_bitmap = ALLOC_REG_SET (NULL); | |
1841 | ||
63b7075c | 1842 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb->next_bb, EXIT_BLOCK_PTR, |
1843 | next_bb) | |
07abdb66 | 1844 | { |
1845 | /* Reset tables used to keep track of what's still valid [since | |
1846 | the start of the block]. */ | |
1847 | reset_opr_set_tables (); | |
1848 | ||
1849 | FOR_BB_INSNS (bb, insn) | |
1850 | if (INSN_P (insn)) | |
1851 | { | |
1852 | changed |= cprop_insn (insn); | |
1853 | ||
1854 | /* Keep track of everything modified by this insn. */ | |
1855 | /* ??? Need to be careful w.r.t. mods done to INSN. | |
1856 | Don't call mark_oprs_set if we turned the | |
72269ab0 | 1857 | insn into a NOTE, or deleted the insn. */ |
1858 | if (! NOTE_P (insn) && ! INSN_DELETED_P (insn)) | |
07abdb66 | 1859 | mark_oprs_set (insn); |
1860 | } | |
1861 | } | |
1862 | ||
1863 | changed |= bypass_conditional_jumps (); | |
540960d1 | 1864 | |
1865 | FREE_REG_SET (reg_set_bitmap); | |
07abdb66 | 1866 | free_cprop_mem (); |
1867 | } | |
522983c2 | 1868 | else |
1869 | { | |
1870 | free (implicit_set_indexes); | |
1871 | implicit_set_indexes = NULL; | |
1872 | } | |
07abdb66 | 1873 | |
1874 | free_hash_table (&set_hash_table); | |
540960d1 | 1875 | obstack_free (&cprop_obstack, NULL); |
07abdb66 | 1876 | |
1877 | if (dump_file) | |
1878 | { | |
1879 | fprintf (dump_file, "CPROP of %s, %d basic blocks, %d bytes needed, ", | |
1880 | current_function_name (), n_basic_blocks, bytes_used); | |
1881 | fprintf (dump_file, "%d local const props, %d local copy props, ", | |
1882 | local_const_prop_count, local_copy_prop_count); | |
1883 | fprintf (dump_file, "%d global const props, %d global copy props\n\n", | |
1884 | global_const_prop_count, global_copy_prop_count); | |
1885 | } | |
1886 | ||
1887 | return changed; | |
1888 | } | |
07abdb66 | 1889 | \f |
1890 | /* All the passes implemented in this file. Each pass has its | |
1891 | own gate and execute function, and at the end of the file a | |
1892 | pass definition for passes.c. | |
1893 | ||
1894 | We do not construct an accurate cfg in functions which call | |
1895 | setjmp, so none of these passes runs if the function calls | |
1896 | setjmp. | |
1897 | FIXME: Should just handle setjmp via REG_SETJMP notes. */ | |
1898 | ||
1899 | static bool | |
1900 | gate_rtl_cprop (void) | |
1901 | { | |
de2ca00d | 1902 | return optimize > 0 && flag_gcse |
1903 | && !cfun->calls_setjmp | |
1904 | && dbg_cnt (cprop); | |
07abdb66 | 1905 | } |
1906 | ||
1907 | static unsigned int | |
1908 | execute_rtl_cprop (void) | |
1909 | { | |
1910 | int changed; | |
1911 | delete_unreachable_blocks (); | |
1912 | df_set_flags (DF_LR_RUN_DCE); | |
1913 | df_analyze (); | |
1914 | changed = one_cprop_pass (); | |
1915 | flag_rerun_cse_after_global_opts |= changed; | |
1916 | if (changed) | |
ec3167d1 | 1917 | cleanup_cfg (CLEANUP_CFG_CHANGED); |
07abdb66 | 1918 | return 0; |
1919 | } | |
1920 | ||
1921 | struct rtl_opt_pass pass_rtl_cprop = | |
1922 | { | |
1923 | { | |
1924 | RTL_PASS, | |
1925 | "cprop", /* name */ | |
1926 | gate_rtl_cprop, /* gate */ | |
1927 | execute_rtl_cprop, /* execute */ | |
1928 | NULL, /* sub */ | |
1929 | NULL, /* next */ | |
1930 | 0, /* static_pass_number */ | |
1931 | TV_CPROP, /* tv_id */ | |
1932 | PROP_cfglayout, /* properties_required */ | |
1933 | 0, /* properties_provided */ | |
1934 | 0, /* properties_destroyed */ | |
1935 | 0, /* todo_flags_start */ | |
1936 | TODO_df_finish | TODO_verify_rtl_sharing | | |
07abdb66 | 1937 | TODO_verify_flow | TODO_ggc_collect /* todo_flags_finish */ |
1938 | } | |
1939 | }; |