1 | /* Global constant/copy propagation for RTL. |
2 | Copyright (C) 1997-2023 Free Software Foundation, Inc. |
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 |
8 | Software Foundation; either version 3, or (at your option) any later |
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 |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ |
19 | |
20 | #include "config.h" |
21 | #include "system.h" |
22 | #include "coretypes.h" |
23 | #include "backend.h" |
24 | #include "rtl.h" |
25 | #include "rtlanal.h" |
26 | #include "cfghooks.h" |
27 | #include "df.h" |
28 | #include "insn-config.h" |
29 | #include "memmodel.h" |
30 | #include "emit-rtl.h" |
31 | #include "recog.h" |
32 | #include "diagnostic-core.h" |
33 | #include "toplev.h" |
34 | #include "cfgrtl.h" |
35 | #include "cfganal.h" |
36 | #include "lcm.h" |
37 | #include "cfgcleanup.h" |
38 | #include "cselib.h" |
39 | #include "intl.h" |
40 | #include "tree-pass.h" |
41 | #include "dbgcnt.h" |
42 | #include "cfgloop.h" |
43 | #include "gcse.h" |
44 | |
45 | |
46 | /* An obstack for our working variables. */ |
47 | static struct obstack cprop_obstack; |
48 | |
49 | /* Occurrence of an expression. |
50 | There is one per basic block. If a pattern appears more than once the |
51 | last appearance is used. */ |
52 | |
53 | struct cprop_occr |
54 | { |
55 | /* Next occurrence of this expression. */ |
56 | struct cprop_occr *next; |
57 | /* The insn that computes the expression. */ |
58 | rtx_insn *insn; |
59 | }; |
60 | |
61 | /* Hash table entry for assignment expressions. */ |
62 | |
63 | struct cprop_expr |
64 | { |
65 | /* The expression (DEST := SRC). */ |
66 | rtx dest; |
67 | rtx src; |
68 | |
69 | /* Index in the available expression bitmaps. */ |
70 | int bitmap_index; |
71 | /* Next entry with the same hash. */ |
72 | struct cprop_expr *next_same_hash; |
73 | /* List of available occurrence in basic blocks in the function. |
74 | An "available occurrence" is one that is the last occurrence in the |
75 | basic block and whose operands are not modified by following statements |
76 | in the basic block [including this insn]. */ |
77 | struct cprop_occr *avail_occr; |
78 | }; |
79 | |
80 | /* Hash table for copy propagation expressions. |
81 | Each hash table is an array of buckets. |
82 | ??? It is known that if it were an array of entries, structure elements |
83 | `next_same_hash' and `bitmap_index' wouldn't be necessary. However, it is |
84 | not clear whether in the final analysis a sufficient amount of memory would |
85 | be saved as the size of the available expression bitmaps would be larger |
86 | [one could build a mapping table without holes afterwards though]. |
87 | Someday I'll perform the computation and figure it out. */ |
88 | |
89 | struct hash_table_d |
90 | { |
91 | /* The table itself. |
92 | This is an array of `set_hash_table_size' elements. */ |
93 | struct cprop_expr **table; |
94 | |
95 | /* Size of the hash table, in elements. */ |
96 | unsigned int size; |
97 | |
98 | /* Number of hash table elements. */ |
99 | unsigned int n_elems; |
100 | }; |
101 | |
102 | /* Copy propagation hash table. */ |
103 | static struct hash_table_d set_hash_table; |
104 | |
105 | /* Array of implicit set patterns indexed by basic block index. */ |
106 | static rtx *implicit_sets; |
107 | |
108 | /* Array of indexes of expressions for implicit set patterns indexed by basic |
109 | block index. In other words, implicit_set_indexes[i] is the bitmap_index |
110 | of the expression whose RTX is implicit_sets[i]. */ |
111 | static int *implicit_set_indexes; |
112 | |
113 | /* Bitmap containing one bit for each register in the program. |
114 | Used when performing GCSE to track which registers have been set since |
115 | the start or end of the basic block while traversing that block. */ |
116 | static regset reg_set_bitmap; |
117 | |
118 | /* Various variables for statistics gathering. */ |
119 | |
120 | /* Memory used in a pass. |
121 | This isn't intended to be absolutely precise. Its intent is only |
122 | to keep an eye on memory usage. */ |
123 | static int bytes_used; |
124 | |
125 | /* Number of local constants propagated. */ |
126 | static int local_const_prop_count; |
127 | /* Number of local copies propagated. */ |
128 | static int local_copy_prop_count; |
129 | /* Number of global constants propagated. */ |
130 | static int global_const_prop_count; |
131 | /* Number of global copies propagated. */ |
132 | static int global_copy_prop_count; |
133 | |
134 | #define GOBNEW(T) ((T *) cprop_alloc (sizeof (T))) |
135 | #define GOBNEWVAR(T, S) ((T *) cprop_alloc ((S))) |
136 | |
137 | /* Cover function to obstack_alloc. */ |
138 | |
139 | static void * |
140 | cprop_alloc (unsigned long size) |
141 | { |
142 | bytes_used += size; |
143 | return obstack_alloc (&cprop_obstack, size); |
144 | } |
145 | |
146 | /* Return true if register X is unchanged from INSN to the end |
147 | of INSN's basic block. */ |
148 | |
149 | static bool |
150 | reg_available_p (const_rtx x, const rtx_insn *insn ATTRIBUTE_UNUSED) |
151 | { |
152 | return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x)); |
153 | } |
154 | |
155 | /* Hash a set of register REGNO. |
156 | |
157 | Sets are hashed on the register that is set. This simplifies the PRE copy |
158 | propagation code. |
159 | |
160 | ??? May need to make things more elaborate. Later, as necessary. */ |
161 | |
162 | static unsigned int |
163 | hash_mod (int regno, int hash_table_size) |
164 | { |
165 | return (unsigned) regno % hash_table_size; |
166 | } |
167 | |
168 | /* Insert assignment DEST:=SET from INSN in the hash table. |
169 | DEST is a register and SET is a register or a suitable constant. |
170 | If the assignment is already present in the table, record it as |
171 | the last occurrence in INSN's basic block. |
172 | IMPLICIT is true if it's an implicit set, false otherwise. */ |
173 | |
174 | static void |
175 | insert_set_in_table (rtx dest, rtx src, rtx_insn *insn, |
176 | struct hash_table_d *table, bool implicit) |
177 | { |
178 | bool found = false; |
179 | unsigned int hash; |
180 | struct cprop_expr *cur_expr, *last_expr = NULL; |
181 | struct cprop_occr *cur_occr; |
182 | |
183 | hash = hash_mod (REGNO (dest), hash_table_size: table->size); |
184 | |
185 | for (cur_expr = table->table[hash]; cur_expr; |
186 | cur_expr = cur_expr->next_same_hash) |
187 | { |
188 | if (dest == cur_expr->dest |
189 | && src == cur_expr->src) |
190 | { |
191 | found = true; |
192 | break; |
193 | } |
194 | last_expr = cur_expr; |
195 | } |
196 | |
197 | if (! found) |
198 | { |
199 | cur_expr = GOBNEW (struct cprop_expr); |
200 | bytes_used += sizeof (struct cprop_expr); |
201 | if (table->table[hash] == NULL) |
202 | /* This is the first pattern that hashed to this index. */ |
203 | table->table[hash] = cur_expr; |
204 | else |
205 | /* Add EXPR to end of this hash chain. */ |
206 | last_expr->next_same_hash = cur_expr; |
207 | |
208 | /* Set the fields of the expr element. |
209 | We must copy X because it can be modified when copy propagation is |
210 | performed on its operands. */ |
211 | cur_expr->dest = copy_rtx (dest); |
212 | cur_expr->src = copy_rtx (src); |
213 | cur_expr->bitmap_index = table->n_elems++; |
214 | cur_expr->next_same_hash = NULL; |
215 | cur_expr->avail_occr = NULL; |
216 | } |
217 | |
218 | /* Now record the occurrence. */ |
219 | cur_occr = cur_expr->avail_occr; |
220 | |
221 | if (cur_occr |
222 | && BLOCK_FOR_INSN (insn: cur_occr->insn) == BLOCK_FOR_INSN (insn)) |
223 | { |
224 | /* Found another instance of the expression in the same basic block. |
225 | Prefer this occurrence to the currently recorded one. We want |
226 | the last one in the block and the block is scanned from start |
227 | to end. */ |
228 | cur_occr->insn = insn; |
229 | } |
230 | else |
231 | { |
232 | /* First occurrence of this expression in this basic block. */ |
233 | cur_occr = GOBNEW (struct cprop_occr); |
234 | bytes_used += sizeof (struct cprop_occr); |
235 | cur_occr->insn = insn; |
236 | cur_occr->next = cur_expr->avail_occr; |
237 | cur_expr->avail_occr = cur_occr; |
238 | } |
239 | |
240 | /* Record bitmap_index of the implicit set in implicit_set_indexes. */ |
241 | if (implicit) |
242 | implicit_set_indexes[BLOCK_FOR_INSN (insn)->index] |
243 | = cur_expr->bitmap_index; |
244 | } |
245 | |
246 | /* Determine whether the rtx X should be treated as a constant for CPROP. |
247 | Since X might be inserted more than once we have to take care that it |
248 | is sharable. */ |
249 | |
250 | static bool |
251 | cprop_constant_p (const_rtx x) |
252 | { |
253 | return CONSTANT_P (x) && (GET_CODE (x) != CONST || shared_const_p (x)); |
254 | } |
255 | |
256 | /* Determine whether the rtx X should be treated as a register that can |
257 | be propagated. Any pseudo-register is fine. */ |
258 | |
259 | static bool |
260 | cprop_reg_p (const_rtx x) |
261 | { |
262 | return REG_P (x) && !HARD_REGISTER_P (x); |
263 | } |
264 | |
265 | /* Scan SET present in INSN and add an entry to the hash TABLE. |
266 | IMPLICIT is true if it's an implicit set, false otherwise. */ |
267 | |
268 | static void |
269 | hash_scan_set (rtx set, rtx_insn *insn, struct hash_table_d *table, |
270 | bool implicit) |
271 | { |
272 | rtx src = SET_SRC (set); |
273 | rtx dest = SET_DEST (set); |
274 | |
275 | if (cprop_reg_p (x: dest) |
276 | && reg_available_p (x: dest, insn) |
277 | && can_copy_p (GET_MODE (dest))) |
278 | { |
279 | /* See if a REG_EQUAL note shows this equivalent to a simpler expression. |
280 | |
281 | This allows us to do a single CPROP pass and still eliminate |
282 | redundant constants, addresses or other expressions that are |
283 | constructed with multiple instructions. |
284 | |
285 | However, keep the original SRC if INSN is a simple reg-reg move. In |
286 | In this case, there will almost always be a REG_EQUAL note on the |
287 | insn that sets SRC. By recording the REG_EQUAL value here as SRC |
288 | for INSN, we miss copy propagation opportunities. |
289 | |
290 | Note that this does not impede profitable constant propagations. We |
291 | "look through" reg-reg sets in lookup_set. */ |
292 | rtx note = find_reg_equal_equiv_note (insn); |
293 | if (note != 0 |
294 | && REG_NOTE_KIND (note) == REG_EQUAL |
295 | && !REG_P (src) |
296 | && cprop_constant_p (XEXP (note, 0))) |
297 | src = XEXP (note, 0), set = gen_rtx_SET (dest, src); |
298 | |
299 | /* Record sets for constant/copy propagation. */ |
300 | if ((cprop_reg_p (x: src) |
301 | && src != dest |
302 | && reg_available_p (x: src, insn)) |
303 | || cprop_constant_p (x: src)) |
304 | insert_set_in_table (dest, src, insn, table, implicit); |
305 | } |
306 | } |
307 | |
308 | /* Process INSN and add hash table entries as appropriate. */ |
309 | |
310 | static void |
311 | hash_scan_insn (rtx_insn *insn, struct hash_table_d *table) |
312 | { |
313 | rtx pat = PATTERN (insn); |
314 | int i; |
315 | |
316 | /* Pick out the sets of INSN and for other forms of instructions record |
317 | what's been modified. */ |
318 | |
319 | if (GET_CODE (pat) == SET) |
320 | hash_scan_set (set: pat, insn, table, implicit: false); |
321 | else if (GET_CODE (pat) == PARALLEL) |
322 | for (i = 0; i < XVECLEN (pat, 0); i++) |
323 | { |
324 | rtx x = XVECEXP (pat, 0, i); |
325 | |
326 | if (GET_CODE (x) == SET) |
327 | hash_scan_set (set: x, insn, table, implicit: false); |
328 | } |
329 | } |
330 | |
331 | /* Dump the hash table TABLE to file FILE under the name NAME. */ |
332 | |
333 | static void |
334 | dump_hash_table (FILE *file, const char *name, struct hash_table_d *table) |
335 | { |
336 | int i; |
337 | /* Flattened out table, so it's printed in proper order. */ |
338 | struct cprop_expr **flat_table; |
339 | unsigned int *hash_val; |
340 | struct cprop_expr *expr; |
341 | |
342 | flat_table = XCNEWVEC (struct cprop_expr *, table->n_elems); |
343 | hash_val = XNEWVEC (unsigned int, table->n_elems); |
344 | |
345 | for (i = 0; i < (int) table->size; i++) |
346 | for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash) |
347 | { |
348 | flat_table[expr->bitmap_index] = expr; |
349 | hash_val[expr->bitmap_index] = i; |
350 | } |
351 | |
352 | fprintf (stream: file, format: "%s hash table (%d buckets, %d entries)\n" , |
353 | name, table->size, table->n_elems); |
354 | |
355 | for (i = 0; i < (int) table->n_elems; i++) |
356 | if (flat_table[i] != 0) |
357 | { |
358 | expr = flat_table[i]; |
359 | fprintf (stream: file, format: "Index %d (hash value %d)\n " , |
360 | expr->bitmap_index, hash_val[i]); |
361 | print_rtl (file, expr->dest); |
362 | fprintf (stream: file, format: " := " ); |
363 | print_rtl (file, expr->src); |
364 | fprintf (stream: file, format: "\n" ); |
365 | } |
366 | |
367 | fprintf (stream: file, format: "\n" ); |
368 | |
369 | free (ptr: flat_table); |
370 | free (ptr: hash_val); |
371 | } |
372 | |
373 | /* Record as unavailable all registers that are DEF operands of INSN. */ |
374 | |
375 | static void |
376 | make_set_regs_unavailable (rtx_insn *insn) |
377 | { |
378 | df_ref def; |
379 | |
380 | FOR_EACH_INSN_DEF (def, insn) |
381 | SET_REGNO_REG_SET (reg_set_bitmap, DF_REF_REGNO (def)); |
382 | } |
383 | |
384 | /* Top level function to create an assignment hash table. |
385 | |
386 | Assignment entries are placed in the hash table if |
387 | - they are of the form (set (pseudo-reg) src), |
388 | - src is something we want to perform const/copy propagation on, |
389 | - none of the operands or target are subsequently modified in the block |
390 | |
391 | Currently src must be a pseudo-reg or a const_int. |
392 | |
393 | TABLE is the table computed. */ |
394 | |
395 | static void |
396 | compute_hash_table_work (struct hash_table_d *table) |
397 | { |
398 | basic_block bb; |
399 | |
400 | /* Allocate vars to track sets of regs. */ |
401 | reg_set_bitmap = ALLOC_REG_SET (NULL); |
402 | |
403 | FOR_EACH_BB_FN (bb, cfun) |
404 | { |
405 | rtx_insn *insn; |
406 | |
407 | /* Reset tables used to keep track of what's not yet invalid [since |
408 | the end of the block]. */ |
409 | CLEAR_REG_SET (reg_set_bitmap); |
410 | |
411 | /* Go over all insns from the last to the first. This is convenient |
412 | for tracking available registers, i.e. not set between INSN and |
413 | the end of the basic block BB. */ |
414 | FOR_BB_INSNS_REVERSE (bb, insn) |
415 | { |
416 | /* Only real insns are interesting. */ |
417 | if (!NONDEBUG_INSN_P (insn)) |
418 | continue; |
419 | |
420 | /* Record interesting sets from INSN in the hash table. */ |
421 | hash_scan_insn (insn, table); |
422 | |
423 | /* Any registers set in INSN will make SETs above it not AVAIL. */ |
424 | make_set_regs_unavailable (insn); |
425 | } |
426 | |
427 | /* Insert implicit sets in the hash table, pretending they appear as |
428 | insns at the head of the basic block. */ |
429 | if (implicit_sets[bb->index] != NULL_RTX) |
430 | hash_scan_set (set: implicit_sets[bb->index], BB_HEAD (bb), table, implicit: true); |
431 | } |
432 | |
433 | FREE_REG_SET (reg_set_bitmap); |
434 | } |
435 | |
436 | /* Allocate space for the set/expr hash TABLE. |
437 | It is used to determine the number of buckets to use. */ |
438 | |
439 | static void |
440 | alloc_hash_table (struct hash_table_d *table) |
441 | { |
442 | int n; |
443 | |
444 | n = get_max_insn_count (); |
445 | |
446 | table->size = n / 4; |
447 | if (table->size < 11) |
448 | table->size = 11; |
449 | |
450 | /* Attempt to maintain efficient use of hash table. |
451 | Making it an odd number is simplest for now. |
452 | ??? Later take some measurements. */ |
453 | table->size |= 1; |
454 | n = table->size * sizeof (struct cprop_expr *); |
455 | table->table = XNEWVAR (struct cprop_expr *, n); |
456 | } |
457 | |
458 | /* Free things allocated by alloc_hash_table. */ |
459 | |
460 | static void |
461 | free_hash_table (struct hash_table_d *table) |
462 | { |
463 | free (ptr: table->table); |
464 | } |
465 | |
466 | /* Compute the hash TABLE for doing copy/const propagation or |
467 | expression hash table. */ |
468 | |
469 | static void |
470 | compute_hash_table (struct hash_table_d *table) |
471 | { |
472 | /* Initialize count of number of entries in hash table. */ |
473 | table->n_elems = 0; |
474 | memset (s: table->table, c: 0, n: table->size * sizeof (struct cprop_expr *)); |
475 | |
476 | compute_hash_table_work (table); |
477 | } |
478 | |
479 | /* Expression tracking support. */ |
480 | |
481 | /* Lookup REGNO in the set TABLE. The result is a pointer to the |
482 | table entry, or NULL if not found. */ |
483 | |
484 | static struct cprop_expr * |
485 | lookup_set (unsigned int regno, struct hash_table_d *table) |
486 | { |
487 | unsigned int hash = hash_mod (regno, hash_table_size: table->size); |
488 | struct cprop_expr *expr; |
489 | |
490 | expr = table->table[hash]; |
491 | |
492 | while (expr && REGNO (expr->dest) != regno) |
493 | expr = expr->next_same_hash; |
494 | |
495 | return expr; |
496 | } |
497 | |
498 | /* Return the next entry for REGNO in list EXPR. */ |
499 | |
500 | static struct cprop_expr * |
501 | next_set (unsigned int regno, struct cprop_expr *expr) |
502 | { |
503 | do |
504 | expr = expr->next_same_hash; |
505 | while (expr && REGNO (expr->dest) != regno); |
506 | |
507 | return expr; |
508 | } |
509 | |
510 | /* Reset tables used to keep track of what's still available [since the |
511 | start of the block]. */ |
512 | |
513 | static void |
514 | reset_opr_set_tables (void) |
515 | { |
516 | /* Maintain a bitmap of which regs have been set since beginning of |
517 | the block. */ |
518 | CLEAR_REG_SET (reg_set_bitmap); |
519 | } |
520 | |
521 | /* Return true if the register X has not been set yet [since the |
522 | start of the basic block containing INSN]. */ |
523 | |
524 | static bool |
525 | reg_not_set_p (const_rtx x, const rtx_insn *insn ATTRIBUTE_UNUSED) |
526 | { |
527 | return ! REGNO_REG_SET_P (reg_set_bitmap, REGNO (x)); |
528 | } |
529 | |
530 | /* Record things set by INSN. |
531 | This data is used by reg_not_set_p. */ |
532 | |
533 | static void |
534 | mark_oprs_set (rtx_insn *insn) |
535 | { |
536 | df_ref def; |
537 | |
538 | FOR_EACH_INSN_DEF (def, insn) |
539 | SET_REGNO_REG_SET (reg_set_bitmap, DF_REF_REGNO (def)); |
540 | } |
541 | |
542 | /* Compute copy/constant propagation working variables. */ |
543 | |
544 | /* Local properties of assignments. */ |
545 | static sbitmap *cprop_avloc; |
546 | static sbitmap *cprop_kill; |
547 | |
548 | /* Global properties of assignments (computed from the local properties). */ |
549 | static sbitmap *cprop_avin; |
550 | static sbitmap *cprop_avout; |
551 | |
552 | /* Allocate vars used for copy/const propagation. N_BLOCKS is the number of |
553 | basic blocks. N_SETS is the number of sets. */ |
554 | |
555 | static void |
556 | alloc_cprop_mem (int n_blocks, int n_sets) |
557 | { |
558 | cprop_avloc = sbitmap_vector_alloc (n_blocks, n_sets); |
559 | cprop_kill = sbitmap_vector_alloc (n_blocks, n_sets); |
560 | |
561 | cprop_avin = sbitmap_vector_alloc (n_blocks, n_sets); |
562 | cprop_avout = sbitmap_vector_alloc (n_blocks, n_sets); |
563 | } |
564 | |
565 | /* Free vars used by copy/const propagation. */ |
566 | |
567 | static void |
568 | free_cprop_mem (void) |
569 | { |
570 | sbitmap_vector_free (vec: cprop_avloc); |
571 | sbitmap_vector_free (vec: cprop_kill); |
572 | sbitmap_vector_free (vec: cprop_avin); |
573 | sbitmap_vector_free (vec: cprop_avout); |
574 | } |
575 | |
576 | /* Compute the local properties of each recorded expression. |
577 | |
578 | Local properties are those that are defined by the block, irrespective of |
579 | other blocks. |
580 | |
581 | An expression is killed in a block if its operands, either DEST or SRC, are |
582 | modified in the block. |
583 | |
584 | An expression is computed (locally available) in a block if it is computed |
585 | at least once and expression would contain the same value if the |
586 | computation was moved to the end of the block. |
587 | |
588 | KILL and COMP are destination sbitmaps for recording local properties. */ |
589 | |
590 | static void |
591 | compute_local_properties (sbitmap *kill, sbitmap *comp, |
592 | struct hash_table_d *table) |
593 | { |
594 | unsigned int i; |
595 | |
596 | /* Initialize the bitmaps that were passed in. */ |
597 | bitmap_vector_clear (kill, last_basic_block_for_fn (cfun)); |
598 | bitmap_vector_clear (comp, last_basic_block_for_fn (cfun)); |
599 | |
600 | for (i = 0; i < table->size; i++) |
601 | { |
602 | struct cprop_expr *expr; |
603 | |
604 | for (expr = table->table[i]; expr != NULL; expr = expr->next_same_hash) |
605 | { |
606 | int indx = expr->bitmap_index; |
607 | df_ref def; |
608 | struct cprop_occr *occr; |
609 | |
610 | /* For each definition of the destination pseudo-reg, the expression |
611 | is killed in the block where the definition is. */ |
612 | for (def = DF_REG_DEF_CHAIN (REGNO (expr->dest)); |
613 | def; def = DF_REF_NEXT_REG (def)) |
614 | bitmap_set_bit (map: kill[DF_REF_BB (def)->index], bitno: indx); |
615 | |
616 | /* If the source is a pseudo-reg, for each definition of the source, |
617 | the expression is killed in the block where the definition is. */ |
618 | if (REG_P (expr->src)) |
619 | for (def = DF_REG_DEF_CHAIN (REGNO (expr->src)); |
620 | def; def = DF_REF_NEXT_REG (def)) |
621 | bitmap_set_bit (map: kill[DF_REF_BB (def)->index], bitno: indx); |
622 | |
623 | /* The occurrences recorded in avail_occr are exactly those that |
624 | are locally available in the block where they are. */ |
625 | for (occr = expr->avail_occr; occr != NULL; occr = occr->next) |
626 | { |
627 | bitmap_set_bit (map: comp[BLOCK_FOR_INSN (insn: occr->insn)->index], bitno: indx); |
628 | } |
629 | } |
630 | } |
631 | } |
632 | |
633 | /* Hash table support. */ |
634 | |
635 | /* Top level routine to do the dataflow analysis needed by copy/const |
636 | propagation. */ |
637 | |
638 | static void |
639 | compute_cprop_data (void) |
640 | { |
641 | basic_block bb; |
642 | |
643 | compute_local_properties (kill: cprop_kill, comp: cprop_avloc, table: &set_hash_table); |
644 | compute_available (cprop_avloc, cprop_kill, cprop_avout, cprop_avin); |
645 | |
646 | /* Merge implicit sets into CPROP_AVIN. They are always available at the |
647 | entry of their basic block. We need to do this because 1) implicit sets |
648 | aren't recorded for the local pass so they cannot be propagated within |
649 | their basic block by this pass and 2) the global pass would otherwise |
650 | propagate them only in the successors of their basic block. */ |
651 | FOR_EACH_BB_FN (bb, cfun) |
652 | { |
653 | int index = implicit_set_indexes[bb->index]; |
654 | if (index != -1) |
655 | bitmap_set_bit (map: cprop_avin[bb->index], bitno: index); |
656 | } |
657 | } |
658 | |
659 | /* Copy/constant propagation. */ |
660 | |
661 | /* Maximum number of register uses in an insn that we handle. */ |
662 | #define MAX_USES 8 |
663 | |
664 | /* Table of uses (registers, both hard and pseudo) found in an insn. |
665 | Allocated statically to avoid alloc/free complexity and overhead. */ |
666 | static rtx reg_use_table[MAX_USES]; |
667 | |
668 | /* Index into `reg_use_table' while building it. */ |
669 | static unsigned reg_use_count; |
670 | |
671 | /* Set up a list of register numbers used in INSN. The found uses are stored |
672 | in `reg_use_table'. `reg_use_count' is initialized to zero before entry, |
673 | and contains the number of uses in the table upon exit. |
674 | |
675 | ??? If a register appears multiple times we will record it multiple times. |
676 | This doesn't hurt anything but it will slow things down. */ |
677 | |
678 | static void |
679 | find_used_regs (rtx *xptr, void *data ATTRIBUTE_UNUSED) |
680 | { |
681 | int i, j; |
682 | enum rtx_code code; |
683 | const char *fmt; |
684 | rtx x = *xptr; |
685 | |
686 | /* repeat is used to turn tail-recursion into iteration since GCC |
687 | can't do it when there's no return value. */ |
688 | repeat: |
689 | if (x == 0) |
690 | return; |
691 | |
692 | code = GET_CODE (x); |
693 | if (REG_P (x)) |
694 | { |
695 | if (reg_use_count == MAX_USES) |
696 | return; |
697 | |
698 | reg_use_table[reg_use_count] = x; |
699 | reg_use_count++; |
700 | } |
701 | |
702 | /* Recursively scan the operands of this expression. */ |
703 | |
704 | for (i = GET_RTX_LENGTH (code) - 1, fmt = GET_RTX_FORMAT (code); i >= 0; i--) |
705 | { |
706 | if (fmt[i] == 'e') |
707 | { |
708 | /* If we are about to do the last recursive call |
709 | needed at this level, change it into iteration. |
710 | This function is called enough to be worth it. */ |
711 | if (i == 0) |
712 | { |
713 | x = XEXP (x, 0); |
714 | goto repeat; |
715 | } |
716 | |
717 | find_used_regs (xptr: &XEXP (x, i), data); |
718 | } |
719 | else if (fmt[i] == 'E') |
720 | for (j = 0; j < XVECLEN (x, i); j++) |
721 | find_used_regs (xptr: &XVECEXP (x, i, j), data); |
722 | } |
723 | } |
724 | |
725 | /* Try to replace all uses of FROM in INSN with TO. |
726 | Return true if successful. */ |
727 | |
728 | static bool |
729 | try_replace_reg (rtx from, rtx to, rtx_insn *insn) |
730 | { |
731 | rtx note = find_reg_equal_equiv_note (insn); |
732 | rtx src = 0; |
733 | bool success = false; |
734 | rtx set = single_set (insn); |
735 | |
736 | bool check_rtx_costs = true; |
737 | bool speed = optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn)); |
738 | int old_cost = set ? set_rtx_cost (x: set, speed_p: speed) : 0; |
739 | |
740 | if (!set |
741 | || CONSTANT_P (SET_SRC (set)) |
742 | || (note != 0 |
743 | && REG_NOTE_KIND (note) == REG_EQUAL |
744 | && (GET_CODE (XEXP (note, 0)) == CONST |
745 | || CONSTANT_P (XEXP (note, 0))))) |
746 | check_rtx_costs = false; |
747 | |
748 | /* Usually we substitute easy stuff, so we won't copy everything. |
749 | We however need to take care to not duplicate non-trivial CONST |
750 | expressions. */ |
751 | to = copy_rtx (to); |
752 | |
753 | validate_replace_src_group (from, to, insn); |
754 | |
755 | /* If TO is a constant, check the cost of the set after propagation |
756 | to the cost of the set before the propagation. If the cost is |
757 | higher, then do not replace FROM with TO. */ |
758 | |
759 | if (check_rtx_costs |
760 | && CONSTANT_P (to) |
761 | && set_rtx_cost (x: set, speed_p: speed) > old_cost) |
762 | { |
763 | cancel_changes (0); |
764 | return false; |
765 | } |
766 | |
767 | |
768 | if (num_changes_pending () && apply_change_group ()) |
769 | success = true; |
770 | |
771 | /* Try to simplify SET_SRC if we have substituted a constant. */ |
772 | if (success && set && CONSTANT_P (to)) |
773 | { |
774 | src = simplify_rtx (SET_SRC (set)); |
775 | |
776 | if (src) |
777 | validate_change (insn, &SET_SRC (set), src, 0); |
778 | } |
779 | |
780 | /* If there is already a REG_EQUAL note, update the expression in it |
781 | with our replacement. */ |
782 | if (note != 0 && REG_NOTE_KIND (note) == REG_EQUAL) |
783 | set_unique_reg_note (insn, REG_EQUAL, |
784 | simplify_replace_rtx (XEXP (note, 0), from, to)); |
785 | if (!success && set && reg_mentioned_p (from, SET_SRC (set))) |
786 | { |
787 | /* If above failed and this is a single set, try to simplify the source |
788 | of the set given our substitution. We could perhaps try this for |
789 | multiple SETs, but it probably won't buy us anything. */ |
790 | src = simplify_replace_rtx (SET_SRC (set), from, to); |
791 | |
792 | if (!rtx_equal_p (src, SET_SRC (set)) |
793 | && validate_change (insn, &SET_SRC (set), src, 0)) |
794 | success = true; |
795 | |
796 | /* If we've failed perform the replacement, have a single SET to |
797 | a REG destination and don't yet have a note, add a REG_EQUAL note |
798 | to not lose information. */ |
799 | if (!success && note == 0 && set != 0 && REG_P (SET_DEST (set)) |
800 | && !contains_paradoxical_subreg_p (SET_SRC (set))) |
801 | note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (src)); |
802 | } |
803 | |
804 | if (set && MEM_P (SET_DEST (set)) && reg_mentioned_p (from, SET_DEST (set))) |
805 | { |
806 | /* Registers can also appear as uses in SET_DEST if it is a MEM. |
807 | We could perhaps try this for multiple SETs, but it probably |
808 | won't buy us anything. */ |
809 | rtx dest = simplify_replace_rtx (SET_DEST (set), from, to); |
810 | |
811 | if (!rtx_equal_p (dest, SET_DEST (set)) |
812 | && validate_change (insn, &SET_DEST (set), dest, 0)) |
813 | success = true; |
814 | } |
815 | |
816 | /* REG_EQUAL may get simplified into register. |
817 | We don't allow that. Remove that note. This code ought |
818 | not to happen, because previous code ought to synthesize |
819 | reg-reg move, but be on the safe side. */ |
820 | if (note && REG_NOTE_KIND (note) == REG_EQUAL && REG_P (XEXP (note, 0))) |
821 | remove_note (insn, note); |
822 | |
823 | return success; |
824 | } |
825 | |
826 | /* Find a set of REGNOs that are available on entry to INSN's block. If found, |
827 | SET_RET[0] will be assigned a set with a register source and SET_RET[1] a |
828 | set with a constant source. If not found the corresponding entry is set to |
829 | NULL. */ |
830 | |
831 | static void |
832 | find_avail_set (int regno, rtx_insn *insn, struct cprop_expr *set_ret[2]) |
833 | { |
834 | set_ret[0] = set_ret[1] = NULL; |
835 | |
836 | /* Loops are not possible here. To get a loop we would need two sets |
837 | available at the start of the block containing INSN. i.e. we would |
838 | need two sets like this available at the start of the block: |
839 | |
840 | (set (reg X) (reg Y)) |
841 | (set (reg Y) (reg X)) |
842 | |
843 | This cannot happen since the set of (reg Y) would have killed the |
844 | set of (reg X) making it unavailable at the start of this block. */ |
845 | while (1) |
846 | { |
847 | rtx src; |
848 | struct cprop_expr *set = lookup_set (regno, table: &set_hash_table); |
849 | |
850 | /* Find a set that is available at the start of the block |
851 | which contains INSN. */ |
852 | while (set) |
853 | { |
854 | if (bitmap_bit_p (map: cprop_avin[BLOCK_FOR_INSN (insn)->index], |
855 | bitno: set->bitmap_index)) |
856 | break; |
857 | set = next_set (regno, expr: set); |
858 | } |
859 | |
860 | /* If no available set was found we've reached the end of the |
861 | (possibly empty) copy chain. */ |
862 | if (set == 0) |
863 | break; |
864 | |
865 | src = set->src; |
866 | |
867 | /* We know the set is available. |
868 | Now check that SRC is locally anticipatable (i.e. none of the |
869 | source operands have changed since the start of the block). |
870 | |
871 | If the source operand changed, we may still use it for the next |
872 | iteration of this loop, but we may not use it for substitutions. */ |
873 | |
874 | if (cprop_constant_p (x: src)) |
875 | set_ret[1] = set; |
876 | else if (reg_not_set_p (x: src, insn)) |
877 | set_ret[0] = set; |
878 | |
879 | /* If the source of the set is anything except a register, then |
880 | we have reached the end of the copy chain. */ |
881 | if (! REG_P (src)) |
882 | break; |
883 | |
884 | /* Follow the copy chain, i.e. start another iteration of the loop |
885 | and see if we have an available copy into SRC. */ |
886 | regno = REGNO (src); |
887 | } |
888 | } |
889 | |
890 | /* Subroutine of cprop_insn that tries to propagate constants into |
891 | JUMP_INSNS. JUMP must be a conditional jump. If SETCC is non-NULL |
892 | it is the instruction that immediately precedes JUMP, and must be a |
893 | single SET of a register. FROM is what we will try to replace, |
894 | SRC is the constant we will try to substitute for it. Return true |
895 | if a change was made. */ |
896 | |
897 | static bool |
898 | cprop_jump (basic_block bb, rtx_insn *setcc, rtx_insn *jump, rtx from, rtx src) |
899 | { |
900 | rtx new_rtx, set_src, note_src; |
901 | rtx set = pc_set (jump); |
902 | rtx note = find_reg_equal_equiv_note (jump); |
903 | |
904 | if (note) |
905 | { |
906 | note_src = XEXP (note, 0); |
907 | if (GET_CODE (note_src) == EXPR_LIST) |
908 | note_src = NULL_RTX; |
909 | } |
910 | else note_src = NULL_RTX; |
911 | |
912 | /* Prefer REG_EQUAL notes except those containing EXPR_LISTs. */ |
913 | set_src = note_src ? note_src : SET_SRC (set); |
914 | |
915 | /* First substitute the SETCC condition into the JUMP instruction, |
916 | then substitute that given values into this expanded JUMP. */ |
917 | if (setcc != NULL_RTX |
918 | && !modified_between_p (from, setcc, jump) |
919 | && !modified_between_p (src, setcc, jump)) |
920 | { |
921 | rtx setcc_src; |
922 | rtx setcc_set = single_set (insn: setcc); |
923 | rtx setcc_note = find_reg_equal_equiv_note (setcc); |
924 | setcc_src = (setcc_note && GET_CODE (XEXP (setcc_note, 0)) != EXPR_LIST) |
925 | ? XEXP (setcc_note, 0) : SET_SRC (setcc_set); |
926 | set_src = simplify_replace_rtx (set_src, SET_DEST (setcc_set), |
927 | setcc_src); |
928 | } |
929 | else |
930 | setcc = NULL; |
931 | |
932 | new_rtx = simplify_replace_rtx (set_src, from, src); |
933 | |
934 | /* If no simplification can be made, then try the next register. */ |
935 | if (rtx_equal_p (new_rtx, SET_SRC (set))) |
936 | return false; |
937 | |
938 | /* If this is now a no-op delete it, otherwise this must be a valid insn. */ |
939 | if (new_rtx == pc_rtx) |
940 | delete_insn (jump); |
941 | else |
942 | { |
943 | /* Ensure the value computed inside the jump insn to be equivalent |
944 | to one computed by setcc. */ |
945 | if (setcc && modified_in_p (new_rtx, setcc)) |
946 | return false; |
947 | if (! validate_unshare_change (jump, &SET_SRC (set), new_rtx, 0)) |
948 | { |
949 | /* When (some) constants are not valid in a comparison, and there |
950 | are two registers to be replaced by constants before the entire |
951 | comparison can be folded into a constant, we need to keep |
952 | intermediate information in REG_EQUAL notes. For targets with |
953 | separate compare insns, such notes are added by try_replace_reg. |
954 | When we have a combined compare-and-branch instruction, however, |
955 | we need to attach a note to the branch itself to make this |
956 | optimization work. */ |
957 | |
958 | if (!rtx_equal_p (new_rtx, note_src)) |
959 | set_unique_reg_note (jump, REG_EQUAL, copy_rtx (new_rtx)); |
960 | return false; |
961 | } |
962 | |
963 | /* Remove REG_EQUAL note after simplification. */ |
964 | if (note_src) |
965 | remove_note (jump, note); |
966 | } |
967 | |
968 | global_const_prop_count++; |
969 | if (dump_file != NULL) |
970 | { |
971 | fprintf (stream: dump_file, |
972 | format: "GLOBAL CONST-PROP: Replacing reg %d in jump_insn %d with " |
973 | "constant " , REGNO (from), INSN_UID (insn: jump)); |
974 | print_rtl (dump_file, src); |
975 | fprintf (stream: dump_file, format: "\n" ); |
976 | } |
977 | purge_dead_edges (bb); |
978 | |
979 | /* If a conditional jump has been changed into unconditional jump, remove |
980 | the jump and make the edge fallthru - this is always called in |
981 | cfglayout mode. */ |
982 | if (new_rtx != pc_rtx && simplejump_p (jump)) |
983 | { |
984 | edge e; |
985 | edge_iterator ei; |
986 | |
987 | FOR_EACH_EDGE (e, ei, bb->succs) |
988 | if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) |
989 | && BB_HEAD (e->dest) == JUMP_LABEL (jump)) |
990 | { |
991 | e->flags |= EDGE_FALLTHRU; |
992 | break; |
993 | } |
994 | delete_insn (jump); |
995 | } |
996 | |
997 | return true; |
998 | } |
999 | |
1000 | /* Subroutine of cprop_insn that tries to propagate constants. FROM is what |
1001 | we will try to replace, SRC is the constant we will try to substitute for |
1002 | it and INSN is the instruction where this will be happening. */ |
1003 | |
1004 | static bool |
1005 | constprop_register (rtx from, rtx src, rtx_insn *insn) |
1006 | { |
1007 | rtx sset; |
1008 | rtx_insn *next_insn; |
1009 | |
1010 | /* Check for reg setting instructions followed by conditional branch |
1011 | instructions first. */ |
1012 | if ((sset = single_set (insn)) != NULL |
1013 | && (next_insn = next_nondebug_insn (insn)) != NULL |
1014 | && any_condjump_p (next_insn) |
1015 | && onlyjump_p (next_insn)) |
1016 | { |
1017 | rtx dest = SET_DEST (sset); |
1018 | if (REG_P (dest) |
1019 | && cprop_jump (bb: BLOCK_FOR_INSN (insn), setcc: insn, jump: next_insn, |
1020 | from, src)) |
1021 | return true; |
1022 | } |
1023 | |
1024 | /* Handle normal insns next. */ |
1025 | if (NONJUMP_INSN_P (insn) && try_replace_reg (from, to: src, insn)) |
1026 | return true; |
1027 | |
1028 | /* Try to propagate a CONST_INT into a conditional jump. |
1029 | We're pretty specific about what we will handle in this |
1030 | code, we can extend this as necessary over time. |
1031 | |
1032 | Right now the insn in question must look like |
1033 | (set (pc) (if_then_else ...)) */ |
1034 | else if (any_condjump_p (insn) && onlyjump_p (insn)) |
1035 | return cprop_jump (bb: BLOCK_FOR_INSN (insn), NULL, jump: insn, from, src); |
1036 | return false; |
1037 | } |
1038 | |
1039 | /* Perform constant and copy propagation on INSN. |
1040 | Return true if a change was made. */ |
1041 | |
1042 | static bool |
1043 | cprop_insn (rtx_insn *insn) |
1044 | { |
1045 | unsigned i; |
1046 | int changed_this_round; |
1047 | bool changed = false; |
1048 | rtx note; |
1049 | |
1050 | do |
1051 | { |
1052 | changed_this_round = 0; |
1053 | reg_use_count = 0; |
1054 | note_uses (&PATTERN (insn), find_used_regs, NULL); |
1055 | |
1056 | /* We may win even when propagating constants into notes. */ |
1057 | note = find_reg_equal_equiv_note (insn); |
1058 | if (note) |
1059 | find_used_regs (xptr: &XEXP (note, 0), NULL); |
1060 | |
1061 | for (i = 0; i < reg_use_count; i++) |
1062 | { |
1063 | rtx reg_used = reg_use_table[i]; |
1064 | unsigned int regno = REGNO (reg_used); |
1065 | rtx src_cst = NULL, src_reg = NULL; |
1066 | struct cprop_expr *set[2]; |
1067 | |
1068 | /* If the register has already been set in this block, there's |
1069 | nothing we can do. */ |
1070 | if (! reg_not_set_p (x: reg_used, insn)) |
1071 | continue; |
1072 | |
1073 | /* Find an assignment that sets reg_used and is available |
1074 | at the start of the block. */ |
1075 | find_avail_set (regno, insn, set_ret: set); |
1076 | if (set[0]) |
1077 | src_reg = set[0]->src; |
1078 | if (set[1]) |
1079 | src_cst = set[1]->src; |
1080 | |
1081 | /* Constant propagation. */ |
1082 | if (src_cst && cprop_constant_p (x: src_cst) |
1083 | && constprop_register (from: reg_used, src: src_cst, insn)) |
1084 | { |
1085 | changed = true; |
1086 | changed_this_round = 1; |
1087 | global_const_prop_count++; |
1088 | if (dump_file != NULL) |
1089 | { |
1090 | fprintf (stream: dump_file, |
1091 | format: "GLOBAL CONST-PROP: Replacing reg %d in " , regno); |
1092 | fprintf (stream: dump_file, format: "insn %d with constant " , |
1093 | INSN_UID (insn)); |
1094 | print_rtl (dump_file, src_cst); |
1095 | fprintf (stream: dump_file, format: "\n" ); |
1096 | } |
1097 | if (insn->deleted ()) |
1098 | return true; |
1099 | } |
1100 | /* Copy propagation. */ |
1101 | else if (src_reg && cprop_reg_p (x: src_reg) |
1102 | && REGNO (src_reg) != regno |
1103 | && try_replace_reg (from: reg_used, to: src_reg, insn)) |
1104 | { |
1105 | changed = true; |
1106 | changed_this_round = 1; |
1107 | global_copy_prop_count++; |
1108 | if (dump_file != NULL) |
1109 | { |
1110 | fprintf (stream: dump_file, |
1111 | format: "GLOBAL COPY-PROP: Replacing reg %d in insn %d" , |
1112 | regno, INSN_UID (insn)); |
1113 | fprintf (stream: dump_file, format: " with reg %d\n" , REGNO (src_reg)); |
1114 | } |
1115 | |
1116 | /* The original insn setting reg_used may or may not now be |
1117 | deletable. We leave the deletion to DCE. */ |
1118 | /* FIXME: If it turns out that the insn isn't deletable, |
1119 | then we may have unnecessarily extended register lifetimes |
1120 | and made things worse. */ |
1121 | } |
1122 | } |
1123 | } |
1124 | /* If try_replace_reg simplified the insn, the regs found by find_used_regs |
1125 | may not be valid anymore. Start over. */ |
1126 | while (changed_this_round); |
1127 | |
1128 | if (changed && DEBUG_INSN_P (insn)) |
1129 | return false; |
1130 | |
1131 | return changed; |
1132 | } |
1133 | |
1134 | /* Like find_used_regs, but avoid recording uses that appear in |
1135 | input-output contexts such as zero_extract or pre_dec. This |
1136 | restricts the cases we consider to those for which local cprop |
1137 | can legitimately make replacements. */ |
1138 | |
1139 | static void |
1140 | local_cprop_find_used_regs (rtx *xptr, void *data) |
1141 | { |
1142 | rtx x = *xptr; |
1143 | |
1144 | if (x == 0) |
1145 | return; |
1146 | |
1147 | switch (GET_CODE (x)) |
1148 | { |
1149 | case ZERO_EXTRACT: |
1150 | case SIGN_EXTRACT: |
1151 | case STRICT_LOW_PART: |
1152 | return; |
1153 | |
1154 | case PRE_DEC: |
1155 | case PRE_INC: |
1156 | case POST_DEC: |
1157 | case POST_INC: |
1158 | case PRE_MODIFY: |
1159 | case POST_MODIFY: |
1160 | /* Can only legitimately appear this early in the context of |
1161 | stack pushes for function arguments, but handle all of the |
1162 | codes nonetheless. */ |
1163 | return; |
1164 | |
1165 | case SUBREG: |
1166 | if (read_modify_subreg_p (x)) |
1167 | return; |
1168 | break; |
1169 | |
1170 | default: |
1171 | break; |
1172 | } |
1173 | |
1174 | find_used_regs (xptr, data); |
1175 | } |
1176 | |
1177 | /* Try to perform local const/copy propagation on X in INSN. */ |
1178 | |
1179 | static bool |
1180 | do_local_cprop (rtx x, rtx_insn *insn) |
1181 | { |
1182 | rtx newreg = NULL, newcnst = NULL; |
1183 | |
1184 | /* Rule out USE instructions and ASM statements as we don't want to |
1185 | change the hard registers mentioned. */ |
1186 | if (REG_P (x) |
1187 | && (cprop_reg_p (x) |
1188 | || (GET_CODE (PATTERN (insn)) != USE |
1189 | && asm_noperands (PATTERN (insn)) < 0))) |
1190 | { |
1191 | cselib_val *val = cselib_lookup (x, GET_MODE (x), 0, VOIDmode); |
1192 | struct elt_loc_list *l; |
1193 | |
1194 | if (!val) |
1195 | return false; |
1196 | for (l = val->locs; l; l = l->next) |
1197 | { |
1198 | rtx this_rtx = l->loc; |
1199 | rtx note; |
1200 | |
1201 | if (cprop_constant_p (x: this_rtx)) |
1202 | newcnst = this_rtx; |
1203 | if (cprop_reg_p (x: this_rtx) |
1204 | /* Don't copy propagate if it has attached REG_EQUIV note. |
1205 | At this point this only function parameters should have |
1206 | REG_EQUIV notes and if the argument slot is used somewhere |
1207 | explicitly, it means address of parameter has been taken, |
1208 | so we should not extend the lifetime of the pseudo. */ |
1209 | && (!(note = find_reg_note (l->setting_insn, REG_EQUIV, NULL_RTX)) |
1210 | || ! MEM_P (XEXP (note, 0)))) |
1211 | newreg = this_rtx; |
1212 | } |
1213 | if (newcnst && constprop_register (from: x, src: newcnst, insn)) |
1214 | { |
1215 | if (dump_file != NULL) |
1216 | { |
1217 | fprintf (stream: dump_file, format: "LOCAL CONST-PROP: Replacing reg %d in " , |
1218 | REGNO (x)); |
1219 | fprintf (stream: dump_file, format: "insn %d with constant " , |
1220 | INSN_UID (insn)); |
1221 | print_rtl (dump_file, newcnst); |
1222 | fprintf (stream: dump_file, format: "\n" ); |
1223 | } |
1224 | local_const_prop_count++; |
1225 | return true; |
1226 | } |
1227 | else if (newreg && newreg != x && try_replace_reg (from: x, to: newreg, insn)) |
1228 | { |
1229 | if (dump_file != NULL) |
1230 | { |
1231 | fprintf (stream: dump_file, |
1232 | format: "LOCAL COPY-PROP: Replacing reg %d in insn %d" , |
1233 | REGNO (x), INSN_UID (insn)); |
1234 | fprintf (stream: dump_file, format: " with reg %d\n" , REGNO (newreg)); |
1235 | } |
1236 | local_copy_prop_count++; |
1237 | return true; |
1238 | } |
1239 | } |
1240 | return false; |
1241 | } |
1242 | |
1243 | /* Do local const/copy propagation (i.e. within each basic block). */ |
1244 | |
1245 | static bool |
1246 | local_cprop_pass (void) |
1247 | { |
1248 | basic_block bb; |
1249 | rtx_insn *insn; |
1250 | bool changed = false; |
1251 | unsigned i; |
1252 | |
1253 | auto_vec<rtx_insn *> uncond_traps; |
1254 | |
1255 | cselib_init (0); |
1256 | FOR_EACH_BB_FN (bb, cfun) |
1257 | { |
1258 | FOR_BB_INSNS (bb, insn) |
1259 | { |
1260 | if (INSN_P (insn)) |
1261 | { |
1262 | bool was_uncond_trap |
1263 | = (GET_CODE (PATTERN (insn)) == TRAP_IF |
1264 | && XEXP (PATTERN (insn), 0) == const1_rtx); |
1265 | rtx note = find_reg_equal_equiv_note (insn); |
1266 | do |
1267 | { |
1268 | reg_use_count = 0; |
1269 | note_uses (&PATTERN (insn), local_cprop_find_used_regs, |
1270 | NULL); |
1271 | if (note) |
1272 | local_cprop_find_used_regs (xptr: &XEXP (note, 0), NULL); |
1273 | |
1274 | for (i = 0; i < reg_use_count; i++) |
1275 | { |
1276 | if (do_local_cprop (x: reg_use_table[i], insn)) |
1277 | { |
1278 | if (!DEBUG_INSN_P (insn)) |
1279 | changed = true; |
1280 | break; |
1281 | } |
1282 | } |
1283 | if (!was_uncond_trap |
1284 | && GET_CODE (PATTERN (insn)) == TRAP_IF |
1285 | && XEXP (PATTERN (insn), 0) == const1_rtx) |
1286 | { |
1287 | uncond_traps.safe_push (obj: insn); |
1288 | break; |
1289 | } |
1290 | if (insn->deleted ()) |
1291 | break; |
1292 | } |
1293 | while (i < reg_use_count); |
1294 | } |
1295 | cselib_process_insn (insn); |
1296 | } |
1297 | |
1298 | /* Forget everything at the end of a basic block. */ |
1299 | cselib_clear_table (); |
1300 | } |
1301 | |
1302 | cselib_finish (); |
1303 | |
1304 | while (!uncond_traps.is_empty ()) |
1305 | { |
1306 | rtx_insn *insn = uncond_traps.pop (); |
1307 | basic_block to_split = BLOCK_FOR_INSN (insn); |
1308 | remove_edge (split_block (to_split, insn)); |
1309 | emit_barrier_after_bb (bb: to_split); |
1310 | } |
1311 | |
1312 | return changed; |
1313 | } |
1314 | |
1315 | /* Similar to get_condition, only the resulting condition must be |
1316 | valid at JUMP, instead of at EARLIEST. |
1317 | |
1318 | This differs from noce_get_condition in ifcvt.cc in that we prefer not to |
1319 | settle for the condition variable in the jump instruction being integral. |
1320 | We prefer to be able to record the value of a user variable, rather than |
1321 | the value of a temporary used in a condition. This could be solved by |
1322 | recording the value of *every* register scanned by canonicalize_condition, |
1323 | but this would require some code reorganization. */ |
1324 | |
1325 | rtx |
1326 | fis_get_condition (rtx_insn *jump) |
1327 | { |
1328 | return get_condition (jump, NULL, false, true); |
1329 | } |
1330 | |
1331 | /* Check the comparison COND to see if we can safely form an implicit |
1332 | set from it. */ |
1333 | |
1334 | static bool |
1335 | implicit_set_cond_p (const_rtx cond) |
1336 | { |
1337 | machine_mode mode; |
1338 | rtx cst; |
1339 | |
1340 | /* COND must be either an EQ or NE comparison. */ |
1341 | if (GET_CODE (cond) != EQ && GET_CODE (cond) != NE) |
1342 | return false; |
1343 | |
1344 | /* The first operand of COND must be a register we can propagate. */ |
1345 | if (!cprop_reg_p (XEXP (cond, 0))) |
1346 | return false; |
1347 | |
1348 | /* The second operand of COND must be a suitable constant. */ |
1349 | mode = GET_MODE (XEXP (cond, 0)); |
1350 | cst = XEXP (cond, 1); |
1351 | |
1352 | /* We can't perform this optimization if either operand might be or might |
1353 | contain a signed zero. */ |
1354 | if (HONOR_SIGNED_ZEROS (mode)) |
1355 | { |
1356 | /* It is sufficient to check if CST is or contains a zero. We must |
1357 | handle float, complex, and vector. If any subpart is a zero, then |
1358 | the optimization can't be performed. */ |
1359 | /* ??? The complex and vector checks are not implemented yet. We just |
1360 | always return false for them. */ |
1361 | if (CONST_DOUBLE_AS_FLOAT_P (cst) |
1362 | && real_equal (CONST_DOUBLE_REAL_VALUE (cst), &dconst0)) |
1363 | return false; |
1364 | else |
1365 | return false; |
1366 | } |
1367 | |
1368 | return cprop_constant_p (x: cst); |
1369 | } |
1370 | |
1371 | /* Find the implicit sets of a function. An "implicit set" is a constraint |
1372 | on the value of a variable, implied by a conditional jump. For example, |
1373 | following "if (x == 2)", the then branch may be optimized as though the |
1374 | conditional performed an "explicit set", in this example, "x = 2". This |
1375 | function records the set patterns that are implicit at the start of each |
1376 | basic block. |
1377 | |
1378 | If an implicit set is found but the set is implicit on a critical edge, |
1379 | this critical edge is split. |
1380 | |
1381 | Return true if the CFG was modified, false otherwise. */ |
1382 | |
1383 | static bool |
1384 | find_implicit_sets (void) |
1385 | { |
1386 | basic_block bb, dest; |
1387 | rtx cond, new_rtx; |
1388 | unsigned int count = 0; |
1389 | bool edges_split = false; |
1390 | size_t implicit_sets_size = last_basic_block_for_fn (cfun) + 10; |
1391 | |
1392 | implicit_sets = XCNEWVEC (rtx, implicit_sets_size); |
1393 | |
1394 | FOR_EACH_BB_FN (bb, cfun) |
1395 | { |
1396 | /* Check for more than one successor. */ |
1397 | if (EDGE_COUNT (bb->succs) <= 1) |
1398 | continue; |
1399 | |
1400 | cond = fis_get_condition (BB_END (bb)); |
1401 | |
1402 | /* If no condition is found or if it isn't of a suitable form, |
1403 | ignore it. */ |
1404 | if (! cond || ! implicit_set_cond_p (cond)) |
1405 | continue; |
1406 | |
1407 | dest = GET_CODE (cond) == EQ |
1408 | ? BRANCH_EDGE (bb)->dest : FALLTHRU_EDGE (bb)->dest; |
1409 | |
1410 | /* If DEST doesn't go anywhere, ignore it. */ |
1411 | if (! dest || dest == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
1412 | continue; |
1413 | |
1414 | /* We have found a suitable implicit set. Try to record it now as |
1415 | a SET in DEST. If DEST has more than one predecessor, the edge |
1416 | between BB and DEST is a critical edge and we must split it, |
1417 | because we can only record one implicit set per DEST basic block. */ |
1418 | if (! single_pred_p (bb: dest)) |
1419 | { |
1420 | dest = split_edge (find_edge (bb, dest)); |
1421 | edges_split = true; |
1422 | } |
1423 | |
1424 | if (implicit_sets_size <= (size_t) dest->index) |
1425 | { |
1426 | size_t old_implicit_sets_size = implicit_sets_size; |
1427 | implicit_sets_size *= 2; |
1428 | implicit_sets = XRESIZEVEC (rtx, implicit_sets, implicit_sets_size); |
1429 | memset (s: implicit_sets + old_implicit_sets_size, c: 0, |
1430 | n: (implicit_sets_size - old_implicit_sets_size) * sizeof (rtx)); |
1431 | } |
1432 | |
1433 | new_rtx = gen_rtx_SET (XEXP (cond, 0), XEXP (cond, 1)); |
1434 | implicit_sets[dest->index] = new_rtx; |
1435 | if (dump_file) |
1436 | { |
1437 | fprintf (stream: dump_file, format: "Implicit set of reg %d in " , |
1438 | REGNO (XEXP (cond, 0))); |
1439 | fprintf (stream: dump_file, format: "basic block %d\n" , dest->index); |
1440 | } |
1441 | count++; |
1442 | } |
1443 | |
1444 | if (dump_file) |
1445 | fprintf (stream: dump_file, format: "Found %d implicit sets\n" , count); |
1446 | |
1447 | /* Confess our sins. */ |
1448 | return edges_split; |
1449 | } |
1450 | |
1451 | /* Bypass conditional jumps. */ |
1452 | |
1453 | /* The value of last_basic_block at the beginning of the jump_bypass |
1454 | pass. The use of redirect_edge_and_branch_force may introduce new |
1455 | basic blocks, but the data flow analysis is only valid for basic |
1456 | block indices less than bypass_last_basic_block. */ |
1457 | |
1458 | static int bypass_last_basic_block; |
1459 | |
1460 | /* Find a set of REGNO to a constant that is available at the end of basic |
1461 | block BB. Return NULL if no such set is found. Based heavily upon |
1462 | find_avail_set. */ |
1463 | |
1464 | static struct cprop_expr * |
1465 | find_bypass_set (int regno, int bb) |
1466 | { |
1467 | struct cprop_expr *result = 0; |
1468 | |
1469 | for (;;) |
1470 | { |
1471 | rtx src; |
1472 | struct cprop_expr *set = lookup_set (regno, table: &set_hash_table); |
1473 | |
1474 | while (set) |
1475 | { |
1476 | if (bitmap_bit_p (map: cprop_avout[bb], bitno: set->bitmap_index)) |
1477 | break; |
1478 | set = next_set (regno, expr: set); |
1479 | } |
1480 | |
1481 | if (set == 0) |
1482 | break; |
1483 | |
1484 | src = set->src; |
1485 | if (cprop_constant_p (x: src)) |
1486 | result = set; |
1487 | |
1488 | if (! REG_P (src)) |
1489 | break; |
1490 | |
1491 | regno = REGNO (src); |
1492 | } |
1493 | return result; |
1494 | } |
1495 | |
1496 | /* Subroutine of bypass_block that checks whether a pseudo is killed by |
1497 | any of the instructions inserted on an edge. Jump bypassing places |
1498 | condition code setters on CFG edges using insert_insn_on_edge. This |
1499 | function is required to check that our data flow analysis is still |
1500 | valid prior to commit_edge_insertions. */ |
1501 | |
1502 | static bool |
1503 | reg_killed_on_edge (const_rtx reg, const_edge e) |
1504 | { |
1505 | rtx_insn *insn; |
1506 | |
1507 | for (insn = e->insns.r; insn; insn = NEXT_INSN (insn)) |
1508 | if (INSN_P (insn) && reg_set_p (reg, insn)) |
1509 | return true; |
1510 | |
1511 | return false; |
1512 | } |
1513 | |
1514 | /* Subroutine of bypass_conditional_jumps that attempts to bypass the given |
1515 | basic block BB which has more than one predecessor. If not NULL, SETCC |
1516 | is the first instruction of BB, which is immediately followed by JUMP_INSN |
1517 | JUMP. Otherwise, SETCC is NULL, and JUMP is the first insn of BB. |
1518 | Returns true if a change was made. |
1519 | |
1520 | During the jump bypassing pass, we may place copies of SETCC instructions |
1521 | on CFG edges. The following routine must be careful to pay attention to |
1522 | these inserted insns when performing its transformations. */ |
1523 | |
1524 | static bool |
1525 | bypass_block (basic_block bb, rtx_insn *setcc, rtx_insn *jump) |
1526 | { |
1527 | rtx_insn *insn; |
1528 | rtx note; |
1529 | edge e, edest; |
1530 | bool change; |
1531 | bool = false; |
1532 | bool removed_p; |
1533 | unsigned i; |
1534 | edge_iterator ei; |
1535 | |
1536 | insn = (setcc != NULL) ? setcc : jump; |
1537 | |
1538 | /* Determine set of register uses in INSN. */ |
1539 | reg_use_count = 0; |
1540 | note_uses (&PATTERN (insn), find_used_regs, NULL); |
1541 | note = find_reg_equal_equiv_note (insn); |
1542 | if (note) |
1543 | find_used_regs (xptr: &XEXP (note, 0), NULL); |
1544 | |
1545 | if (current_loops) |
1546 | { |
1547 | /* If we are to preserve loop structure then do not bypass |
1548 | a loop header. This will either rotate the loop, create |
1549 | multiple entry loops or even irreducible regions. */ |
1550 | if (bb == bb->loop_father->header) |
1551 | return 0; |
1552 | } |
1553 | else |
1554 | { |
1555 | FOR_EACH_EDGE (e, ei, bb->preds) |
1556 | if (e->flags & EDGE_DFS_BACK) |
1557 | { |
1558 | may_be_loop_header = true; |
1559 | break; |
1560 | } |
1561 | } |
1562 | |
1563 | change = false; |
1564 | for (ei = ei_start (bb->preds); (e = ei_safe_edge (i: ei)); ) |
1565 | { |
1566 | removed_p = false; |
1567 | |
1568 | if (e->flags & EDGE_COMPLEX) |
1569 | { |
1570 | ei_next (i: &ei); |
1571 | continue; |
1572 | } |
1573 | |
1574 | /* We can't redirect edges from new basic blocks. */ |
1575 | if (e->src->index >= bypass_last_basic_block) |
1576 | { |
1577 | ei_next (i: &ei); |
1578 | continue; |
1579 | } |
1580 | |
1581 | /* The irreducible loops created by redirecting of edges entering the |
1582 | loop from outside would decrease effectiveness of some of the |
1583 | following optimizations, so prevent this. */ |
1584 | if (may_be_loop_header |
1585 | && !(e->flags & EDGE_DFS_BACK)) |
1586 | { |
1587 | ei_next (i: &ei); |
1588 | continue; |
1589 | } |
1590 | |
1591 | for (i = 0; i < reg_use_count; i++) |
1592 | { |
1593 | rtx reg_used = reg_use_table[i]; |
1594 | unsigned int regno = REGNO (reg_used); |
1595 | basic_block dest, old_dest; |
1596 | struct cprop_expr *set; |
1597 | rtx src, new_rtx; |
1598 | |
1599 | set = find_bypass_set (regno, bb: e->src->index); |
1600 | |
1601 | if (! set) |
1602 | continue; |
1603 | |
1604 | /* Check the data flow is valid after edge insertions. */ |
1605 | if (e->insns.r && reg_killed_on_edge (reg: reg_used, e)) |
1606 | continue; |
1607 | |
1608 | src = SET_SRC (pc_set (jump)); |
1609 | |
1610 | if (setcc != NULL) |
1611 | src = simplify_replace_rtx (src, |
1612 | SET_DEST (PATTERN (setcc)), |
1613 | SET_SRC (PATTERN (setcc))); |
1614 | |
1615 | new_rtx = simplify_replace_rtx (src, reg_used, set->src); |
1616 | |
1617 | /* Jump bypassing may have already placed instructions on |
1618 | edges of the CFG. We can't bypass an outgoing edge that |
1619 | has instructions associated with it, as these insns won't |
1620 | get executed if the incoming edge is redirected. */ |
1621 | if (new_rtx == pc_rtx) |
1622 | { |
1623 | edest = FALLTHRU_EDGE (bb); |
1624 | dest = edest->insns.r ? NULL : edest->dest; |
1625 | } |
1626 | else if (GET_CODE (new_rtx) == LABEL_REF) |
1627 | { |
1628 | dest = BLOCK_FOR_INSN (XEXP (new_rtx, 0)); |
1629 | /* Don't bypass edges containing instructions. */ |
1630 | if (dest) |
1631 | { |
1632 | edest = find_edge (bb, dest); |
1633 | if (edest && edest->insns.r) |
1634 | dest = NULL; |
1635 | } |
1636 | } |
1637 | else |
1638 | dest = NULL; |
1639 | |
1640 | /* Avoid unification of the edge with other edges from original |
1641 | branch. We would end up emitting the instruction on "both" |
1642 | edges. */ |
1643 | if (dest && setcc && find_edge (e->src, dest)) |
1644 | dest = NULL; |
1645 | |
1646 | old_dest = e->dest; |
1647 | if (dest != NULL |
1648 | && dest != old_dest |
1649 | && dest != EXIT_BLOCK_PTR_FOR_FN (cfun)) |
1650 | { |
1651 | redirect_edge_and_branch_force (e, dest); |
1652 | |
1653 | /* Copy the register setter to the redirected edge. */ |
1654 | if (setcc) |
1655 | { |
1656 | rtx pat = PATTERN (insn: setcc); |
1657 | insert_insn_on_edge (copy_insn (pat), e); |
1658 | } |
1659 | |
1660 | if (dump_file != NULL) |
1661 | { |
1662 | fprintf (stream: dump_file, format: "JUMP-BYPASS: Proved reg %d " |
1663 | "in jump_insn %d equals constant " , |
1664 | regno, INSN_UID (insn: jump)); |
1665 | print_rtl (dump_file, set->src); |
1666 | fprintf (stream: dump_file, format: "\n\t when BB %d is entered from " |
1667 | "BB %d. Redirect edge %d->%d to %d.\n" , |
1668 | old_dest->index, e->src->index, e->src->index, |
1669 | old_dest->index, dest->index); |
1670 | } |
1671 | change = true; |
1672 | removed_p = true; |
1673 | break; |
1674 | } |
1675 | } |
1676 | if (!removed_p) |
1677 | ei_next (i: &ei); |
1678 | } |
1679 | return change; |
1680 | } |
1681 | |
1682 | /* Find basic blocks with more than one predecessor that only contain a |
1683 | single conditional jump. If the result of the comparison is known at |
1684 | compile-time from any incoming edge, redirect that edge to the |
1685 | appropriate target. Return nonzero if a change was made. |
1686 | |
1687 | This function is now mis-named, because we also handle indirect jumps. */ |
1688 | |
1689 | static bool |
1690 | bypass_conditional_jumps (void) |
1691 | { |
1692 | basic_block bb; |
1693 | bool changed; |
1694 | rtx_insn *setcc; |
1695 | rtx_insn *insn; |
1696 | rtx dest; |
1697 | |
1698 | /* Note we start at block 1. */ |
1699 | if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
1700 | return false; |
1701 | |
1702 | mark_dfs_back_edges (); |
1703 | |
1704 | changed = false; |
1705 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb->next_bb, |
1706 | EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb) |
1707 | { |
1708 | /* Check for more than one predecessor. */ |
1709 | if (!single_pred_p (bb)) |
1710 | { |
1711 | setcc = NULL; |
1712 | FOR_BB_INSNS (bb, insn) |
1713 | if (DEBUG_INSN_P (insn)) |
1714 | continue; |
1715 | else if (NONJUMP_INSN_P (insn)) |
1716 | { |
1717 | if (setcc) |
1718 | break; |
1719 | if (GET_CODE (PATTERN (insn)) != SET) |
1720 | break; |
1721 | |
1722 | dest = SET_DEST (PATTERN (insn)); |
1723 | if (REG_P (dest)) |
1724 | setcc = insn; |
1725 | else |
1726 | break; |
1727 | } |
1728 | else if (JUMP_P (insn)) |
1729 | { |
1730 | if ((any_condjump_p (insn) || computed_jump_p (insn)) |
1731 | && onlyjump_p (insn)) |
1732 | if (bypass_block (bb, setcc, jump: insn)) |
1733 | changed = true; |
1734 | break; |
1735 | } |
1736 | else if (INSN_P (insn)) |
1737 | break; |
1738 | } |
1739 | } |
1740 | |
1741 | /* If we bypassed any register setting insns, we inserted a |
1742 | copy on the redirected edge. These need to be committed. */ |
1743 | if (changed) |
1744 | commit_edge_insertions (); |
1745 | |
1746 | return changed; |
1747 | } |
1748 | |
1749 | /* Main function for the CPROP pass. */ |
1750 | |
1751 | static bool |
1752 | one_cprop_pass (void) |
1753 | { |
1754 | bool changed = false; |
1755 | int i; |
1756 | |
1757 | /* Return if there's nothing to do, or it is too expensive. */ |
1758 | if (n_basic_blocks_for_fn (cfun) <= NUM_FIXED_BLOCKS + 1 |
1759 | || gcse_or_cprop_is_too_expensive (_ ("const/copy propagation disabled" ))) |
1760 | return false; |
1761 | |
1762 | global_const_prop_count = local_const_prop_count = 0; |
1763 | global_copy_prop_count = local_copy_prop_count = 0; |
1764 | |
1765 | bytes_used = 0; |
1766 | gcc_obstack_init (&cprop_obstack); |
1767 | |
1768 | /* Do a local const/copy propagation pass first. The global pass |
1769 | only handles global opportunities. |
1770 | If the local pass changes something, remove any unreachable blocks |
1771 | because the CPROP global dataflow analysis may get into infinite |
1772 | loops for CFGs with unreachable blocks. |
1773 | |
1774 | FIXME: This local pass should not be necessary after CSE (but for |
1775 | some reason it still is). It is also (proven) not necessary |
1776 | to run the local pass right after FWPWOP. |
1777 | |
1778 | FIXME: The global analysis would not get into infinite loops if it |
1779 | would use the DF solver (via df_simple_dataflow) instead of |
1780 | the solver implemented in this file. */ |
1781 | if (local_cprop_pass ()) |
1782 | changed = true; |
1783 | |
1784 | if (changed) |
1785 | delete_unreachable_blocks (); |
1786 | |
1787 | /* Determine implicit sets. This may change the CFG (split critical |
1788 | edges if that exposes an implicit set). |
1789 | Note that find_implicit_sets() does not rely on up-to-date DF caches |
1790 | so that we do not have to re-run df_analyze() even if local CPROP |
1791 | changed something. |
1792 | ??? This could run earlier so that any uncovered implicit sets |
1793 | sets could be exploited in local_cprop_pass() also. Later. */ |
1794 | if (find_implicit_sets ()) |
1795 | changed = true; |
1796 | |
1797 | /* If local_cprop_pass() or find_implicit_sets() changed something, |
1798 | run df_analyze() to bring all insn caches up-to-date, and to take |
1799 | new basic blocks from edge splitting on the DF radar. |
1800 | NB: This also runs the fast DCE pass, because execute_rtl_cprop |
1801 | sets DF_LR_RUN_DCE. */ |
1802 | if (changed) |
1803 | df_analyze (); |
1804 | |
1805 | /* Initialize implicit_set_indexes array. */ |
1806 | implicit_set_indexes = XNEWVEC (int, last_basic_block_for_fn (cfun)); |
1807 | for (i = 0; i < last_basic_block_for_fn (cfun); i++) |
1808 | implicit_set_indexes[i] = -1; |
1809 | |
1810 | alloc_hash_table (table: &set_hash_table); |
1811 | compute_hash_table (table: &set_hash_table); |
1812 | |
1813 | /* Free implicit_sets before peak usage. */ |
1814 | free (ptr: implicit_sets); |
1815 | implicit_sets = NULL; |
1816 | |
1817 | if (dump_file) |
1818 | dump_hash_table (file: dump_file, name: "SET" , table: &set_hash_table); |
1819 | if (set_hash_table.n_elems > 0) |
1820 | { |
1821 | basic_block bb; |
1822 | auto_vec<rtx_insn *> uncond_traps; |
1823 | |
1824 | alloc_cprop_mem (last_basic_block_for_fn (cfun), |
1825 | n_sets: set_hash_table.n_elems); |
1826 | compute_cprop_data (); |
1827 | |
1828 | free (ptr: implicit_set_indexes); |
1829 | implicit_set_indexes = NULL; |
1830 | |
1831 | /* Allocate vars to track sets of regs. */ |
1832 | reg_set_bitmap = ALLOC_REG_SET (NULL); |
1833 | |
1834 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb->next_bb, |
1835 | EXIT_BLOCK_PTR_FOR_FN (cfun), |
1836 | next_bb) |
1837 | { |
1838 | bool seen_uncond_trap = false; |
1839 | rtx_insn *insn; |
1840 | |
1841 | /* Reset tables used to keep track of what's still valid [since |
1842 | the start of the block]. */ |
1843 | reset_opr_set_tables (); |
1844 | |
1845 | FOR_BB_INSNS (bb, insn) |
1846 | if (INSN_P (insn)) |
1847 | { |
1848 | bool was_uncond_trap |
1849 | = (GET_CODE (PATTERN (insn)) == TRAP_IF |
1850 | && XEXP (PATTERN (insn), 0) == const1_rtx); |
1851 | |
1852 | if (cprop_insn (insn)) |
1853 | changed = true; |
1854 | |
1855 | /* Keep track of everything modified by this insn. */ |
1856 | /* ??? Need to be careful w.r.t. mods done to INSN. |
1857 | Don't call mark_oprs_set if we turned the |
1858 | insn into a NOTE, or deleted the insn. */ |
1859 | if (! NOTE_P (insn) && ! insn->deleted ()) |
1860 | mark_oprs_set (insn); |
1861 | |
1862 | if (!was_uncond_trap |
1863 | && GET_CODE (PATTERN (insn)) == TRAP_IF |
1864 | && XEXP (PATTERN (insn), 0) == const1_rtx) |
1865 | { |
1866 | /* If we have already seen an unconditional trap |
1867 | earlier, the rest of the bb is going to be removed |
1868 | as unreachable. Just turn it into a note, so that |
1869 | RTL verification doesn't complain about it before |
1870 | it is finally removed. */ |
1871 | if (seen_uncond_trap) |
1872 | set_insn_deleted (insn); |
1873 | else |
1874 | { |
1875 | seen_uncond_trap = true; |
1876 | uncond_traps.safe_push (obj: insn); |
1877 | } |
1878 | } |
1879 | } |
1880 | } |
1881 | |
1882 | /* Make sure bypass_conditional_jumps will ignore not just its new |
1883 | basic blocks, but also the ones after unconditional traps (those are |
1884 | unreachable and will be eventually removed as such). */ |
1885 | bypass_last_basic_block = last_basic_block_for_fn (cfun); |
1886 | |
1887 | while (!uncond_traps.is_empty ()) |
1888 | { |
1889 | rtx_insn *insn = uncond_traps.pop (); |
1890 | basic_block to_split = BLOCK_FOR_INSN (insn); |
1891 | remove_edge (split_block (to_split, insn)); |
1892 | emit_barrier_after_bb (bb: to_split); |
1893 | } |
1894 | |
1895 | if (bypass_conditional_jumps ()) |
1896 | changed = true; |
1897 | |
1898 | FREE_REG_SET (reg_set_bitmap); |
1899 | free_cprop_mem (); |
1900 | } |
1901 | else |
1902 | { |
1903 | free (ptr: implicit_set_indexes); |
1904 | implicit_set_indexes = NULL; |
1905 | } |
1906 | |
1907 | free_hash_table (table: &set_hash_table); |
1908 | obstack_free (&cprop_obstack, NULL); |
1909 | |
1910 | if (dump_file) |
1911 | { |
1912 | fprintf (stream: dump_file, format: "CPROP of %s, %d basic blocks, %d bytes needed, " , |
1913 | current_function_name (), n_basic_blocks_for_fn (cfun), |
1914 | bytes_used); |
1915 | fprintf (stream: dump_file, format: "%d local const props, %d local copy props, " , |
1916 | local_const_prop_count, local_copy_prop_count); |
1917 | fprintf (stream: dump_file, format: "%d global const props, %d global copy props\n\n" , |
1918 | global_const_prop_count, global_copy_prop_count); |
1919 | } |
1920 | |
1921 | return changed; |
1922 | } |
1923 | |
1924 | /* All the passes implemented in this file. Each pass has its |
1925 | own gate and execute function, and at the end of the file a |
1926 | pass definition for passes.cc. |
1927 | |
1928 | We do not construct an accurate cfg in functions which call |
1929 | setjmp, so none of these passes runs if the function calls |
1930 | setjmp. |
1931 | FIXME: Should just handle setjmp via REG_SETJMP notes. */ |
1932 | |
1933 | static unsigned int |
1934 | execute_rtl_cprop (void) |
1935 | { |
1936 | int changed; |
1937 | delete_unreachable_blocks (); |
1938 | df_set_flags (DF_LR_RUN_DCE); |
1939 | df_analyze (); |
1940 | changed = one_cprop_pass (); |
1941 | flag_rerun_cse_after_global_opts |= changed; |
1942 | if (changed) |
1943 | cleanup_cfg (CLEANUP_CFG_CHANGED); |
1944 | return 0; |
1945 | } |
1946 | |
1947 | namespace { |
1948 | |
1949 | const pass_data pass_data_rtl_cprop = |
1950 | { |
1951 | .type: RTL_PASS, /* type */ |
1952 | .name: "cprop" , /* name */ |
1953 | .optinfo_flags: OPTGROUP_NONE, /* optinfo_flags */ |
1954 | .tv_id: TV_CPROP, /* tv_id */ |
1955 | PROP_cfglayout, /* properties_required */ |
1956 | .properties_provided: 0, /* properties_provided */ |
1957 | .properties_destroyed: 0, /* properties_destroyed */ |
1958 | .todo_flags_start: 0, /* todo_flags_start */ |
1959 | TODO_df_finish, /* todo_flags_finish */ |
1960 | }; |
1961 | |
1962 | class pass_rtl_cprop : public rtl_opt_pass |
1963 | { |
1964 | public: |
1965 | pass_rtl_cprop (gcc::context *ctxt) |
1966 | : rtl_opt_pass (pass_data_rtl_cprop, ctxt) |
1967 | {} |
1968 | |
1969 | /* opt_pass methods: */ |
1970 | opt_pass * clone () final override { return new pass_rtl_cprop (m_ctxt); } |
1971 | bool gate (function *fun) final override |
1972 | { |
1973 | return optimize > 0 && flag_gcse |
1974 | && !fun->calls_setjmp |
1975 | && dbg_cnt (index: cprop); |
1976 | } |
1977 | |
1978 | unsigned int execute (function *) final override |
1979 | { |
1980 | return execute_rtl_cprop (); |
1981 | } |
1982 | |
1983 | }; // class pass_rtl_cprop |
1984 | |
1985 | } // anon namespace |
1986 | |
1987 | rtl_opt_pass * |
1988 | make_pass_rtl_cprop (gcc::context *ctxt) |
1989 | { |
1990 | return new pass_rtl_cprop (ctxt); |
1991 | } |
1992 | |