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5e962776 | 1 | /* Rtl-level loop invariant motion. |
c8d3e15a | 2 | Copyright (C) 2004, 2005 Free Software Foundation, Inc. |
5e962776 ZD |
3 | |
4 | This file is part of GCC. | |
5 | ||
6 | GCC is free software; you can redistribute it and/or modify it | |
7 | under the terms of the GNU General Public License as published by the | |
8 | Free Software Foundation; either version 2, or (at your option) any | |
9 | later version. | |
10 | ||
11 | GCC is distributed in the hope that it will be useful, but WITHOUT | |
12 | ANY 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 COPYING. If not, write to the Free | |
366ccddb KC |
18 | Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA |
19 | 02110-1301, USA. */ | |
5e962776 ZD |
20 | |
21 | /* This implements the loop invariant motion pass. It is very simple | |
22 | (no calls, libcalls, etc.). This should be sufficient to cleanup things like | |
23 | address arithmetics -- other more complicated invariants should be | |
24 | eliminated on tree level either in tree-ssa-loop-im.c or in tree-ssa-pre.c. | |
25 | ||
26 | We proceed loop by loop -- it is simpler than trying to handle things | |
27 | globally and should not lose much. First we inspect all sets inside loop | |
28 | and create a dependency graph on insns (saying "to move this insn, you must | |
29 | also move the following insns"). | |
30 | ||
31 | We then need to determine what to move. We estimate the number of registers | |
32 | used and move as many invariants as possible while we still have enough free | |
33 | registers. We prefer the expensive invariants. | |
34 | ||
35 | Then we move the selected invariants out of the loop, creating a new | |
36 | temporaries for them if necessary. */ | |
37 | ||
38 | #include "config.h" | |
39 | #include "system.h" | |
40 | #include "coretypes.h" | |
41 | #include "tm.h" | |
42 | #include "rtl.h" | |
43 | #include "hard-reg-set.h" | |
7932a3db | 44 | #include "obstack.h" |
5e962776 ZD |
45 | #include "basic-block.h" |
46 | #include "cfgloop.h" | |
47 | #include "expr.h" | |
48 | #include "output.h" | |
49 | #include "function.h" | |
50 | #include "flags.h" | |
51 | #include "df.h" | |
52 | ||
53 | /* The data stored for the loop. */ | |
54 | ||
55 | struct loop_data | |
56 | { | |
57 | struct loop *outermost_exit; /* The outermost exit of the loop. */ | |
58 | bool has_call; /* True if the loop contains a call. */ | |
59 | }; | |
60 | ||
61 | #define LOOP_DATA(LOOP) ((struct loop_data *) (LOOP)->aux) | |
62 | ||
63 | /* The description of an use. */ | |
64 | ||
65 | struct use | |
66 | { | |
67 | rtx *pos; /* Position of the use. */ | |
68 | rtx insn; /* The insn in that the use occurs. */ | |
69 | ||
70 | struct use *next; /* Next use in the list. */ | |
71 | }; | |
72 | ||
73 | /* The description of a def. */ | |
74 | ||
75 | struct def | |
76 | { | |
77 | struct use *uses; /* The list of uses that are uniquely reached | |
78 | by it. */ | |
79 | unsigned n_uses; /* Number of such uses. */ | |
80 | unsigned invno; /* The corresponding invariant. */ | |
81 | }; | |
82 | ||
83 | /* The data stored for each invariant. */ | |
84 | ||
85 | struct invariant | |
86 | { | |
87 | /* The number of the invariant. */ | |
88 | unsigned invno; | |
89 | ||
90 | /* Whether we already processed the invariant. */ | |
91 | bool processed; | |
92 | ||
93 | /* The definition of the invariant. */ | |
94 | struct def *def; | |
95 | ||
96 | /* The insn in that it is defined. */ | |
97 | rtx insn; | |
98 | ||
99 | /* Whether it is always executed. */ | |
100 | bool always_executed; | |
101 | ||
102 | /* Whether to move the invariant. */ | |
103 | bool move; | |
104 | ||
105 | /* Cost if the invariant. */ | |
106 | unsigned cost; | |
107 | ||
108 | /* The invariants it depends on. */ | |
109 | bitmap depends_on; | |
110 | ||
111 | /* Used for detecting already visited invariants during determining | |
112 | costs of movements. */ | |
113 | unsigned stamp; | |
114 | }; | |
115 | ||
116 | /* The actual stamp for marking already visited invariants during determining | |
117 | costs of movements. */ | |
118 | ||
119 | static unsigned actual_stamp; | |
120 | ||
edd954e6 KH |
121 | typedef struct invariant *invariant_p; |
122 | ||
123 | DEF_VEC_P(invariant_p); | |
124 | DEF_VEC_ALLOC_P(invariant_p, heap); | |
125 | ||
5e962776 ZD |
126 | /* The invariants. */ |
127 | ||
edd954e6 | 128 | static VEC(invariant_p,heap) *invariants; |
5e962776 ZD |
129 | |
130 | /* Test for possibility of invariantness of X. */ | |
131 | ||
132 | static bool | |
133 | check_maybe_invariant (rtx x) | |
134 | { | |
135 | enum rtx_code code = GET_CODE (x); | |
136 | int i, j; | |
137 | const char *fmt; | |
138 | ||
139 | switch (code) | |
140 | { | |
141 | case CONST_INT: | |
142 | case CONST_DOUBLE: | |
143 | case SYMBOL_REF: | |
144 | case CONST: | |
145 | case LABEL_REF: | |
146 | return true; | |
147 | ||
148 | case PC: | |
149 | case CC0: | |
150 | case UNSPEC_VOLATILE: | |
151 | case CALL: | |
152 | return false; | |
153 | ||
154 | case REG: | |
155 | return true; | |
156 | ||
157 | case MEM: | |
158 | /* Load/store motion is done elsewhere. ??? Perhaps also add it here? | |
159 | It should not be hard, and might be faster than "elsewhere". */ | |
160 | ||
161 | /* Just handle the most trivial case where we load from an unchanging | |
162 | location (most importantly, pic tables). */ | |
389fdba0 | 163 | if (MEM_READONLY_P (x)) |
5e962776 ZD |
164 | break; |
165 | ||
166 | return false; | |
167 | ||
168 | case ASM_OPERANDS: | |
169 | /* Don't mess with insns declared volatile. */ | |
170 | if (MEM_VOLATILE_P (x)) | |
171 | return false; | |
172 | break; | |
173 | ||
174 | default: | |
175 | break; | |
176 | } | |
177 | ||
178 | fmt = GET_RTX_FORMAT (code); | |
179 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
180 | { | |
181 | if (fmt[i] == 'e') | |
182 | { | |
183 | if (!check_maybe_invariant (XEXP (x, i))) | |
184 | return false; | |
185 | } | |
186 | else if (fmt[i] == 'E') | |
187 | { | |
188 | for (j = 0; j < XVECLEN (x, i); j++) | |
189 | if (!check_maybe_invariant (XVECEXP (x, i, j))) | |
190 | return false; | |
191 | } | |
192 | } | |
193 | ||
194 | return true; | |
195 | } | |
196 | ||
197 | /* Determines the basic blocks inside LOOP that are always executed and | |
198 | stores their bitmap to ALWAYS_REACHED. MAY_EXIT is a bitmap of | |
199 | basic blocks that may either exit the loop, or contain the call that | |
200 | does not have to return. BODY is body of the loop obtained by | |
201 | get_loop_body_in_dom_order. */ | |
202 | ||
203 | static void | |
204 | compute_always_reached (struct loop *loop, basic_block *body, | |
205 | bitmap may_exit, bitmap always_reached) | |
206 | { | |
207 | unsigned i; | |
208 | ||
209 | for (i = 0; i < loop->num_nodes; i++) | |
210 | { | |
211 | if (dominated_by_p (CDI_DOMINATORS, loop->latch, body[i])) | |
212 | bitmap_set_bit (always_reached, i); | |
213 | ||
214 | if (bitmap_bit_p (may_exit, i)) | |
215 | return; | |
216 | } | |
217 | } | |
218 | ||
219 | /* Finds exits out of the LOOP with body BODY. Marks blocks in that we may | |
220 | exit the loop by cfg edge to HAS_EXIT and MAY_EXIT. In MAY_EXIT | |
221 | additionally mark blocks that may exit due to a call. */ | |
222 | ||
223 | static void | |
224 | find_exits (struct loop *loop, basic_block *body, | |
225 | bitmap may_exit, bitmap has_exit) | |
226 | { | |
227 | unsigned i; | |
628f6a4e | 228 | edge_iterator ei; |
5e962776 ZD |
229 | edge e; |
230 | struct loop *outermost_exit = loop, *aexit; | |
231 | bool has_call = false; | |
232 | rtx insn; | |
233 | ||
234 | for (i = 0; i < loop->num_nodes; i++) | |
235 | { | |
236 | if (body[i]->loop_father == loop) | |
237 | { | |
238 | FOR_BB_INSNS (body[i], insn) | |
239 | { | |
4b4bf941 | 240 | if (CALL_P (insn) |
5e962776 ZD |
241 | && !CONST_OR_PURE_CALL_P (insn)) |
242 | { | |
243 | has_call = true; | |
244 | bitmap_set_bit (may_exit, i); | |
245 | break; | |
246 | } | |
247 | } | |
248 | ||
628f6a4e | 249 | FOR_EACH_EDGE (e, ei, body[i]->succs) |
5e962776 ZD |
250 | { |
251 | if (flow_bb_inside_loop_p (loop, e->dest)) | |
252 | continue; | |
253 | ||
254 | bitmap_set_bit (may_exit, i); | |
255 | bitmap_set_bit (has_exit, i); | |
256 | outermost_exit = find_common_loop (outermost_exit, | |
257 | e->dest->loop_father); | |
258 | } | |
259 | continue; | |
260 | } | |
261 | ||
262 | /* Use the data stored for the subloop to decide whether we may exit | |
263 | through it. It is sufficient to do this for header of the loop, | |
264 | as other basic blocks inside it must be dominated by it. */ | |
265 | if (body[i]->loop_father->header != body[i]) | |
266 | continue; | |
267 | ||
268 | if (LOOP_DATA (body[i]->loop_father)->has_call) | |
269 | { | |
270 | has_call = true; | |
271 | bitmap_set_bit (may_exit, i); | |
272 | } | |
273 | aexit = LOOP_DATA (body[i]->loop_father)->outermost_exit; | |
274 | if (aexit != loop) | |
275 | { | |
276 | bitmap_set_bit (may_exit, i); | |
277 | bitmap_set_bit (has_exit, i); | |
278 | ||
279 | if (flow_loop_nested_p (aexit, outermost_exit)) | |
280 | outermost_exit = aexit; | |
281 | } | |
282 | } | |
283 | ||
284 | loop->aux = xcalloc (1, sizeof (struct loop_data)); | |
285 | LOOP_DATA (loop)->outermost_exit = outermost_exit; | |
286 | LOOP_DATA (loop)->has_call = has_call; | |
287 | } | |
288 | ||
289 | /* Check whether we may assign a value to X from a register. */ | |
290 | ||
291 | static bool | |
292 | may_assign_reg_p (rtx x) | |
293 | { | |
a7f4ccb1 SB |
294 | return (can_copy_p (GET_MODE (x)) |
295 | && (!REG_P (x) | |
296 | || !HARD_REGISTER_P (x) | |
297 | || REGNO_REG_CLASS (REGNO (x)) != NO_REGS)); | |
5e962776 ZD |
298 | } |
299 | ||
300 | /* Finds definitions that may correspond to invariants in LOOP with body BODY. | |
301 | DF is the dataflow object. */ | |
302 | ||
303 | static void | |
304 | find_defs (struct loop *loop, basic_block *body, struct df *df) | |
305 | { | |
306 | unsigned i; | |
8bdbfff5 | 307 | bitmap blocks = BITMAP_ALLOC (NULL); |
5e962776 ZD |
308 | |
309 | for (i = 0; i < loop->num_nodes; i++) | |
310 | bitmap_set_bit (blocks, body[i]->index); | |
311 | ||
312 | df_analyze_subcfg (df, blocks, DF_UD_CHAIN | DF_HARD_REGS | DF_EQUIV_NOTES); | |
8bdbfff5 | 313 | BITMAP_FREE (blocks); |
5e962776 ZD |
314 | } |
315 | ||
316 | /* Creates a new invariant for definition DEF in INSN, depending on invariants | |
317 | in DEPENDS_ON. ALWAYS_EXECUTED is true if the insn is always executed, | |
318 | unless the program ends due to a function call. */ | |
319 | ||
320 | static void | |
321 | create_new_invariant (struct def *def, rtx insn, bitmap depends_on, | |
322 | bool always_executed) | |
323 | { | |
324 | struct invariant *inv = xmalloc (sizeof (struct invariant)); | |
325 | rtx set = single_set (insn); | |
326 | ||
327 | inv->def = def; | |
328 | inv->always_executed = always_executed; | |
329 | inv->depends_on = depends_on; | |
330 | ||
331 | /* If the set is simple, usually by moving it we move the whole store out of | |
332 | the loop. Otherwise we save only cost of the computation. */ | |
333 | if (def) | |
334 | inv->cost = rtx_cost (set, SET); | |
335 | else | |
336 | inv->cost = rtx_cost (SET_SRC (set), SET); | |
337 | ||
338 | inv->move = false; | |
339 | inv->processed = false; | |
340 | inv->stamp = 0; | |
341 | inv->insn = insn; | |
342 | ||
edd954e6 | 343 | inv->invno = VEC_length (invariant_p, invariants); |
5e962776 ZD |
344 | if (def) |
345 | def->invno = inv->invno; | |
edd954e6 | 346 | VEC_safe_push (invariant_p, heap, invariants, inv); |
5e962776 ZD |
347 | |
348 | if (dump_file) | |
349 | { | |
350 | fprintf (dump_file, | |
351 | "Set in insn %d is invariant (%d), cost %d, depends on ", | |
352 | INSN_UID (insn), inv->invno, inv->cost); | |
353 | dump_bitmap (dump_file, inv->depends_on); | |
354 | } | |
355 | } | |
356 | ||
357 | /* Record USE at DEF. */ | |
358 | ||
359 | static void | |
360 | record_use (struct def *def, rtx *use, rtx insn) | |
361 | { | |
362 | struct use *u = xmalloc (sizeof (struct use)); | |
363 | ||
364 | if (GET_CODE (*use) == SUBREG) | |
365 | use = &SUBREG_REG (*use); | |
b5e624c6 | 366 | gcc_assert (REG_P (*use)); |
5e962776 ZD |
367 | |
368 | u->pos = use; | |
369 | u->insn = insn; | |
370 | u->next = def->uses; | |
371 | def->uses = u; | |
372 | def->n_uses++; | |
373 | } | |
374 | ||
375 | /* Finds the invariants INSN depends on and store them to the DEPENDS_ON | |
376 | bitmap. DF is the dataflow object. */ | |
377 | ||
378 | static bool | |
379 | check_dependencies (rtx insn, struct df *df, bitmap depends_on) | |
380 | { | |
381 | struct df_link *uses, *defs; | |
382 | struct ref *use, *def; | |
383 | basic_block bb = BLOCK_FOR_INSN (insn), def_bb; | |
384 | struct def *def_data; | |
385 | ||
386 | for (uses = DF_INSN_USES (df, insn); uses; uses = uses->next) | |
387 | { | |
388 | use = uses->ref; | |
389 | ||
390 | defs = DF_REF_CHAIN (use); | |
391 | if (!defs) | |
392 | continue; | |
393 | ||
394 | if (defs->next) | |
395 | return false; | |
396 | ||
397 | def = defs->ref; | |
398 | def_data = DF_REF_DATA (def); | |
399 | if (!def_data) | |
400 | return false; | |
401 | ||
402 | def_bb = DF_REF_BB (def); | |
403 | if (!dominated_by_p (CDI_DOMINATORS, bb, def_bb)) | |
404 | return false; | |
405 | ||
406 | bitmap_set_bit (depends_on, def_data->invno); | |
407 | } | |
408 | ||
409 | return true; | |
410 | } | |
411 | ||
412 | /* Finds invariant in INSN. ALWAYS_REACHED is true if the insn is always | |
413 | executed. ALWAYS_EXECUTED is true if the insn is always executed, | |
414 | unless the program ends due to a function call. DF is the dataflow | |
415 | object. */ | |
416 | ||
417 | static void | |
418 | find_invariant_insn (rtx insn, bool always_reached, bool always_executed, | |
419 | struct df *df) | |
420 | { | |
421 | struct ref *ref; | |
422 | struct def *def; | |
423 | bitmap depends_on; | |
424 | rtx set, dest; | |
425 | bool simple = true; | |
426 | ||
427 | /* Until we get rid of LIBCALLS. */ | |
428 | if (find_reg_note (insn, REG_RETVAL, NULL_RTX) | |
429 | || find_reg_note (insn, REG_LIBCALL, NULL_RTX) | |
430 | || find_reg_note (insn, REG_NO_CONFLICT, NULL_RTX)) | |
431 | return; | |
432 | ||
433 | set = single_set (insn); | |
434 | if (!set) | |
435 | return; | |
436 | dest = SET_DEST (set); | |
437 | ||
2ca202e7 | 438 | if (!REG_P (dest) |
5e962776 ZD |
439 | || HARD_REGISTER_P (dest)) |
440 | simple = false; | |
441 | ||
a7f4ccb1 SB |
442 | if (!may_assign_reg_p (SET_DEST (set)) |
443 | || !check_maybe_invariant (SET_SRC (set))) | |
5e962776 ZD |
444 | return; |
445 | ||
446 | if (may_trap_p (PATTERN (insn))) | |
447 | { | |
448 | if (!always_reached) | |
449 | return; | |
450 | ||
451 | /* Unless the exceptions are handled, the behavior is undefined | |
452 | if the trap occurs. */ | |
453 | if (flag_non_call_exceptions) | |
454 | return; | |
455 | } | |
456 | ||
8bdbfff5 | 457 | depends_on = BITMAP_ALLOC (NULL); |
5e962776 ZD |
458 | if (!check_dependencies (insn, df, depends_on)) |
459 | { | |
8bdbfff5 | 460 | BITMAP_FREE (depends_on); |
5e962776 ZD |
461 | return; |
462 | } | |
463 | ||
464 | if (simple) | |
465 | { | |
466 | ref = df_find_def (df, insn, dest); | |
467 | def = xcalloc (1, sizeof (struct def)); | |
468 | DF_REF_DATA (ref) = def; | |
469 | } | |
470 | else | |
471 | def = NULL; | |
472 | ||
473 | create_new_invariant (def, insn, depends_on, always_executed); | |
474 | } | |
475 | ||
569b7f6a | 476 | /* Record registers used in INSN that have a unique invariant definition. |
5e962776 ZD |
477 | DF is the dataflow object. */ |
478 | ||
479 | static void | |
480 | record_uses (rtx insn, struct df *df) | |
481 | { | |
482 | struct df_link *uses, *defs; | |
483 | struct ref *use, *def; | |
484 | basic_block bb = BLOCK_FOR_INSN (insn), def_bb; | |
485 | ||
486 | for (uses = DF_INSN_USES (df, insn); uses; uses = uses->next) | |
487 | { | |
488 | use = uses->ref; | |
489 | ||
490 | defs = DF_REF_CHAIN (use); | |
491 | if (!defs || defs->next) | |
492 | continue; | |
493 | def = defs->ref; | |
494 | if (!DF_REF_DATA (def)) | |
495 | continue; | |
496 | ||
497 | def_bb = DF_REF_BB (def); | |
498 | if (!dominated_by_p (CDI_DOMINATORS, bb, def_bb)) | |
499 | continue; | |
500 | ||
501 | record_use (DF_REF_DATA (def), DF_REF_LOC (use), DF_REF_INSN (use)); | |
502 | } | |
503 | } | |
504 | ||
505 | /* Finds invariants in INSN. ALWAYS_REACHED is true if the insn is always | |
506 | executed. ALWAYS_EXECUTED is true if the insn is always executed, | |
507 | unless the program ends due to a function call. DF is the dataflow | |
508 | object. */ | |
509 | ||
510 | static void | |
511 | find_invariants_insn (rtx insn, bool always_reached, bool always_executed, | |
512 | struct df *df) | |
513 | { | |
514 | find_invariant_insn (insn, always_reached, always_executed, df); | |
515 | record_uses (insn, df); | |
516 | } | |
517 | ||
518 | /* Finds invariants in basic block BB. ALWAYS_REACHED is true if the | |
519 | basic block is always executed. ALWAYS_EXECUTED is true if the basic | |
520 | block is always executed, unless the program ends due to a function | |
521 | call. DF is the dataflow object. */ | |
522 | ||
523 | static void | |
524 | find_invariants_bb (basic_block bb, bool always_reached, bool always_executed, | |
525 | struct df *df) | |
526 | { | |
527 | rtx insn; | |
528 | ||
529 | FOR_BB_INSNS (bb, insn) | |
530 | { | |
531 | if (!INSN_P (insn)) | |
532 | continue; | |
533 | ||
534 | find_invariants_insn (insn, always_reached, always_executed, df); | |
535 | ||
536 | if (always_reached | |
4b4bf941 | 537 | && CALL_P (insn) |
5e962776 ZD |
538 | && !CONST_OR_PURE_CALL_P (insn)) |
539 | always_reached = false; | |
540 | } | |
541 | } | |
542 | ||
543 | /* Finds invariants in LOOP with body BODY. ALWAYS_REACHED is the bitmap of | |
544 | basic blocks in BODY that are always executed. ALWAYS_EXECUTED is the | |
545 | bitmap of basic blocks in BODY that are always executed unless the program | |
546 | ends due to a function call. DF is the dataflow object. */ | |
547 | ||
548 | static void | |
549 | find_invariants_body (struct loop *loop, basic_block *body, | |
550 | bitmap always_reached, bitmap always_executed, | |
551 | struct df *df) | |
552 | { | |
553 | unsigned i; | |
554 | ||
555 | for (i = 0; i < loop->num_nodes; i++) | |
556 | find_invariants_bb (body[i], | |
557 | bitmap_bit_p (always_reached, i), | |
558 | bitmap_bit_p (always_executed, i), | |
559 | df); | |
560 | } | |
561 | ||
562 | /* Finds invariants in LOOP. DF is the dataflow object. */ | |
563 | ||
564 | static void | |
565 | find_invariants (struct loop *loop, struct df *df) | |
566 | { | |
8bdbfff5 NS |
567 | bitmap may_exit = BITMAP_ALLOC (NULL); |
568 | bitmap always_reached = BITMAP_ALLOC (NULL); | |
569 | bitmap has_exit = BITMAP_ALLOC (NULL); | |
570 | bitmap always_executed = BITMAP_ALLOC (NULL); | |
5e962776 ZD |
571 | basic_block *body = get_loop_body_in_dom_order (loop); |
572 | ||
573 | find_exits (loop, body, may_exit, has_exit); | |
574 | compute_always_reached (loop, body, may_exit, always_reached); | |
575 | compute_always_reached (loop, body, has_exit, always_executed); | |
576 | ||
577 | find_defs (loop, body, df); | |
578 | find_invariants_body (loop, body, always_reached, always_executed, df); | |
579 | ||
8bdbfff5 NS |
580 | BITMAP_FREE (always_reached); |
581 | BITMAP_FREE (always_executed); | |
582 | BITMAP_FREE (may_exit); | |
583 | BITMAP_FREE (has_exit); | |
5e962776 ZD |
584 | free (body); |
585 | } | |
586 | ||
587 | /* Frees a list of uses USE. */ | |
588 | ||
589 | static void | |
590 | free_use_list (struct use *use) | |
591 | { | |
592 | struct use *next; | |
593 | ||
594 | for (; use; use = next) | |
595 | { | |
596 | next = use->next; | |
597 | free (use); | |
598 | } | |
599 | } | |
600 | ||
601 | /* Calculates cost and number of registers needed for moving invariant INV | |
602 | out of the loop and stores them to *COST and *REGS_NEEDED. */ | |
603 | ||
604 | static void | |
605 | get_inv_cost (struct invariant *inv, int *comp_cost, unsigned *regs_needed) | |
606 | { | |
607 | int acomp_cost; | |
608 | unsigned aregs_needed; | |
609 | unsigned depno; | |
610 | struct invariant *dep; | |
87c476a2 | 611 | bitmap_iterator bi; |
5e962776 ZD |
612 | |
613 | *comp_cost = 0; | |
614 | *regs_needed = 0; | |
615 | if (inv->move | |
616 | || inv->stamp == actual_stamp) | |
617 | return; | |
618 | inv->stamp = actual_stamp; | |
619 | ||
620 | (*regs_needed)++; | |
621 | (*comp_cost) += inv->cost; | |
622 | ||
87c476a2 | 623 | EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, depno, bi) |
5e962776 | 624 | { |
edd954e6 | 625 | dep = VEC_index (invariant_p, invariants, depno); |
5e962776 ZD |
626 | |
627 | get_inv_cost (dep, &acomp_cost, &aregs_needed); | |
628 | ||
629 | if (aregs_needed | |
630 | /* We need to check always_executed, since if the original value of | |
631 | the invariant may be preserved, we may need to keep it in a | |
632 | separate register. TODO check whether the register has an | |
633 | use outside of the loop. */ | |
634 | && dep->always_executed | |
635 | && !dep->def->uses->next) | |
636 | { | |
637 | /* If this is a single use, after moving the dependency we will not | |
638 | need a new register. */ | |
639 | aregs_needed--; | |
640 | } | |
641 | ||
642 | (*regs_needed) += aregs_needed; | |
643 | (*comp_cost) += acomp_cost; | |
87c476a2 | 644 | } |
5e962776 ZD |
645 | } |
646 | ||
647 | /* Calculates gain for eliminating invariant INV. REGS_USED is the number | |
648 | of registers used in the loop, N_INV_USES is the number of uses of | |
649 | invariants, NEW_REGS is the number of new variables already added due to | |
650 | the invariant motion. The number of registers needed for it is stored in | |
651 | *REGS_NEEDED. */ | |
652 | ||
653 | static int | |
654 | gain_for_invariant (struct invariant *inv, unsigned *regs_needed, | |
655 | unsigned new_regs, unsigned regs_used, unsigned n_inv_uses) | |
656 | { | |
657 | int comp_cost, size_cost; | |
658 | ||
659 | get_inv_cost (inv, &comp_cost, regs_needed); | |
660 | actual_stamp++; | |
661 | ||
662 | size_cost = (global_cost_for_size (new_regs + *regs_needed, | |
663 | regs_used, n_inv_uses) | |
664 | - global_cost_for_size (new_regs, regs_used, n_inv_uses)); | |
665 | ||
666 | return comp_cost - size_cost; | |
667 | } | |
668 | ||
669 | /* Finds invariant with best gain for moving. Returns the gain, stores | |
670 | the invariant in *BEST and number of registers needed for it to | |
671 | *REGS_NEEDED. REGS_USED is the number of registers used in | |
672 | the loop, N_INV_USES is the number of uses of invariants. NEW_REGS | |
673 | is the number of new variables already added due to invariant motion. */ | |
674 | ||
675 | static int | |
676 | best_gain_for_invariant (struct invariant **best, unsigned *regs_needed, | |
677 | unsigned new_regs, unsigned regs_used, | |
678 | unsigned n_inv_uses) | |
679 | { | |
680 | struct invariant *inv; | |
681 | int gain = 0, again; | |
682 | unsigned aregs_needed, invno; | |
683 | ||
edd954e6 | 684 | for (invno = 0; VEC_iterate (invariant_p, invariants, invno, inv); invno++) |
5e962776 | 685 | { |
5e962776 ZD |
686 | if (inv->move) |
687 | continue; | |
688 | ||
689 | again = gain_for_invariant (inv, &aregs_needed, | |
690 | new_regs, regs_used, n_inv_uses); | |
691 | if (again > gain) | |
692 | { | |
693 | gain = again; | |
694 | *best = inv; | |
695 | *regs_needed = aregs_needed; | |
696 | } | |
697 | } | |
698 | ||
699 | return gain; | |
700 | } | |
701 | ||
702 | /* Marks invariant INVNO and all its dependencies for moving. */ | |
703 | ||
704 | static void | |
705 | set_move_mark (unsigned invno) | |
706 | { | |
edd954e6 | 707 | struct invariant *inv = VEC_index (invariant_p, invariants, invno); |
87c476a2 | 708 | bitmap_iterator bi; |
5e962776 ZD |
709 | |
710 | if (inv->move) | |
711 | return; | |
712 | inv->move = true; | |
713 | ||
714 | if (dump_file) | |
715 | fprintf (dump_file, "Decided to move invariant %d\n", invno); | |
716 | ||
87c476a2 ZD |
717 | EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, invno, bi) |
718 | { | |
719 | set_move_mark (invno); | |
720 | } | |
5e962776 ZD |
721 | } |
722 | ||
723 | /* Determines which invariants to move. DF is the dataflow object. */ | |
724 | ||
725 | static void | |
726 | find_invariants_to_move (struct df *df) | |
727 | { | |
728 | unsigned i, regs_used, n_inv_uses, regs_needed = 0, new_regs; | |
729 | struct invariant *inv = NULL; | |
730 | ||
edd954e6 | 731 | if (!VEC_length (invariant_p, invariants)) |
5e962776 ZD |
732 | return; |
733 | ||
734 | /* Now something slightly more involved. First estimate the number of used | |
735 | registers. */ | |
736 | n_inv_uses = 0; | |
737 | ||
738 | /* We do not really do a good job in this estimation; put some initial bound | |
739 | here to stand for induction variables etc. that we do not detect. */ | |
740 | regs_used = 2; | |
741 | ||
742 | for (i = 0; i < df->n_regs; i++) | |
743 | { | |
744 | if (!DF_REGNO_FIRST_DEF (df, i) && DF_REGNO_LAST_USE (df, i)) | |
745 | { | |
746 | /* This is a value that is used but not changed inside loop. */ | |
747 | regs_used++; | |
748 | } | |
749 | } | |
750 | ||
edd954e6 | 751 | for (i = 0; VEC_iterate (invariant_p, invariants, i, inv); i++) |
5e962776 | 752 | { |
5e962776 ZD |
753 | if (inv->def) |
754 | n_inv_uses += inv->def->n_uses; | |
755 | } | |
756 | ||
757 | new_regs = 0; | |
758 | while (best_gain_for_invariant (&inv, ®s_needed, | |
759 | new_regs, regs_used, n_inv_uses) > 0) | |
760 | { | |
761 | set_move_mark (inv->invno); | |
762 | new_regs += regs_needed; | |
763 | } | |
764 | } | |
765 | ||
766 | /* Move invariant INVNO out of the LOOP. DF is the dataflow object. */ | |
767 | ||
768 | static void | |
769 | move_invariant_reg (struct loop *loop, unsigned invno, struct df *df) | |
770 | { | |
edd954e6 | 771 | struct invariant *inv = VEC_index (invariant_p, invariants, invno); |
5e962776 ZD |
772 | unsigned i; |
773 | basic_block preheader = loop_preheader_edge (loop)->src; | |
774 | rtx reg, set; | |
775 | struct use *use; | |
87c476a2 | 776 | bitmap_iterator bi; |
5e962776 ZD |
777 | |
778 | if (inv->processed) | |
779 | return; | |
780 | inv->processed = true; | |
781 | ||
782 | if (inv->depends_on) | |
783 | { | |
87c476a2 | 784 | EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, i, bi) |
5e962776 ZD |
785 | { |
786 | move_invariant_reg (loop, i, df); | |
87c476a2 | 787 | } |
5e962776 ZD |
788 | } |
789 | ||
790 | /* Move the set out of the loop. If the set is always executed (we could | |
791 | omit this condition if we know that the register is unused outside of the | |
792 | loop, but it does not seem worth finding out) and it has no uses that | |
793 | would not be dominated by it, we may just move it (TODO). Otherwise we | |
794 | need to create a temporary register. */ | |
795 | set = single_set (inv->insn); | |
796 | reg = gen_reg_rtx (GET_MODE (SET_DEST (set))); | |
797 | df_pattern_emit_after (df, gen_move_insn (SET_DEST (set), reg), | |
798 | BLOCK_FOR_INSN (inv->insn), inv->insn); | |
b644b211 SB |
799 | |
800 | /* If the SET_DEST of the invariant insn is a reg, we can just move | |
801 | the insn out of the loop. Otherwise, we have to use gen_move_insn | |
802 | to let emit_move_insn produce a valid instruction stream. */ | |
803 | if (REG_P (SET_DEST (set))) | |
804 | { | |
805 | SET_DEST (set) = reg; | |
806 | reorder_insns (inv->insn, inv->insn, BB_END (preheader)); | |
807 | df_insn_modify (df, preheader, inv->insn); | |
808 | } | |
809 | else | |
810 | { | |
811 | df_pattern_emit_after (df, gen_move_insn (reg, SET_SRC (set)), | |
812 | preheader, BB_END (preheader)); | |
813 | df_insn_delete (df, BLOCK_FOR_INSN (inv->insn), inv->insn); | |
814 | } | |
5e962776 ZD |
815 | |
816 | /* Replace the uses we know to be dominated. It saves work for copy | |
817 | propagation, and also it is necessary so that dependent invariants | |
818 | are computed right. */ | |
819 | if (inv->def) | |
820 | { | |
821 | for (use = inv->def->uses; use; use = use->next) | |
822 | { | |
823 | *use->pos = reg; | |
824 | df_insn_modify (df, BLOCK_FOR_INSN (use->insn), use->insn); | |
825 | } | |
826 | } | |
827 | } | |
828 | ||
829 | /* Move selected invariant out of the LOOP. Newly created regs are marked | |
830 | in TEMPORARY_REGS. DF is the dataflow object. */ | |
831 | ||
832 | static void | |
833 | move_invariants (struct loop *loop, struct df *df) | |
834 | { | |
835 | struct invariant *inv; | |
836 | unsigned i; | |
837 | ||
edd954e6 | 838 | for (i = 0; VEC_iterate (invariant_p, invariants, i, inv); i++) |
5e962776 | 839 | { |
5e962776 ZD |
840 | if (inv->move) |
841 | move_invariant_reg (loop, i, df); | |
842 | } | |
843 | } | |
844 | ||
845 | /* Initializes invariant motion data. */ | |
846 | ||
847 | static void | |
848 | init_inv_motion_data (void) | |
849 | { | |
850 | actual_stamp = 1; | |
851 | ||
edd954e6 | 852 | invariants = VEC_alloc (invariant_p, heap, 100); |
5e962776 ZD |
853 | } |
854 | ||
855 | /* Frees the data allocated by invariant motion. DF is the dataflow | |
856 | object. */ | |
857 | ||
858 | static void | |
859 | free_inv_motion_data (struct df *df) | |
860 | { | |
861 | unsigned i; | |
862 | struct def *def; | |
863 | struct invariant *inv; | |
864 | ||
865 | for (i = 0; i < df->n_defs; i++) | |
866 | { | |
867 | if (!df->defs[i]) | |
868 | continue; | |
869 | ||
870 | def = DF_REF_DATA (df->defs[i]); | |
871 | if (!def) | |
872 | continue; | |
873 | ||
874 | free_use_list (def->uses); | |
875 | free (def); | |
876 | DF_REF_DATA (df->defs[i]) = NULL; | |
877 | } | |
878 | ||
edd954e6 | 879 | for (i = 0; VEC_iterate (invariant_p, invariants, i, inv); i++) |
5e962776 | 880 | { |
8bdbfff5 | 881 | BITMAP_FREE (inv->depends_on); |
5e962776 ZD |
882 | free (inv); |
883 | } | |
edd954e6 | 884 | VEC_free (invariant_p, heap, invariants); |
5e962776 ZD |
885 | } |
886 | ||
887 | /* Move the invariants out of the LOOP. DF is the dataflow object. */ | |
888 | ||
889 | static void | |
890 | move_single_loop_invariants (struct loop *loop, struct df *df) | |
891 | { | |
892 | init_inv_motion_data (); | |
893 | ||
894 | find_invariants (loop, df); | |
895 | find_invariants_to_move (df); | |
896 | move_invariants (loop, df); | |
897 | ||
898 | free_inv_motion_data (df); | |
899 | } | |
900 | ||
901 | /* Releases the auxiliary data for LOOP. */ | |
902 | ||
903 | static void | |
904 | free_loop_data (struct loop *loop) | |
905 | { | |
906 | struct loop_data *data = LOOP_DATA (loop); | |
907 | ||
908 | free (data); | |
909 | loop->aux = NULL; | |
910 | } | |
911 | ||
912 | /* Move the invariants out of the LOOPS. */ | |
913 | ||
914 | void | |
915 | move_loop_invariants (struct loops *loops) | |
916 | { | |
917 | struct loop *loop; | |
918 | unsigned i; | |
919 | struct df *df = df_init (); | |
920 | ||
921 | /* Process the loops, innermost first. */ | |
922 | loop = loops->tree_root; | |
923 | while (loop->inner) | |
924 | loop = loop->inner; | |
925 | ||
926 | while (loop != loops->tree_root) | |
927 | { | |
928 | move_single_loop_invariants (loop, df); | |
929 | ||
930 | if (loop->next) | |
931 | { | |
932 | loop = loop->next; | |
933 | while (loop->inner) | |
934 | loop = loop->inner; | |
935 | } | |
936 | else | |
937 | loop = loop->outer; | |
938 | } | |
939 | ||
940 | for (i = 1; i < loops->num; i++) | |
941 | if (loops->parray[i]) | |
942 | free_loop_data (loops->parray[i]); | |
943 | ||
944 | df_finish (df); | |
a7f4ccb1 SB |
945 | |
946 | #ifdef ENABLE_CHECKING | |
947 | verify_flow_info (); | |
948 | #endif | |
5e962776 | 949 | } |