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3072d30e | 1 | /* RTL dead code elimination. |
711789cc | 2 | Copyright (C) 2005-2013 Free Software Foundation, Inc. |
3072d30e | 3 | |
4 | This file is part of GCC. | |
5 | ||
6 | GCC is free software; you can redistribute it and/or modify it under | |
7 | the terms of the GNU General Public License as published by the Free | |
8c4c00c1 | 8 | Software Foundation; either version 3, or (at your option) any later |
3072d30e | 9 | version. |
10 | ||
11 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 | for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
8c4c00c1 | 17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
3072d30e | 19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
23 | #include "hashtab.h" | |
24 | #include "tm.h" | |
25 | #include "rtl.h" | |
26 | #include "tree.h" | |
27 | #include "regs.h" | |
28 | #include "hard-reg-set.h" | |
29 | #include "flags.h" | |
14ca6b9a | 30 | #include "except.h" |
3072d30e | 31 | #include "df.h" |
32 | #include "cselib.h" | |
33 | #include "dce.h" | |
e6637753 | 34 | #include "valtrack.h" |
3072d30e | 35 | #include "tree-pass.h" |
36 | #include "dbgcnt.h" | |
eb940a48 | 37 | #include "tm_p.h" |
06f9d6ef | 38 | #include "emit-rtl.h" /* FIXME: Can go away once crtl is moved to rtl.h. */ |
3072d30e | 39 | |
3072d30e | 40 | |
41 | /* ------------------------------------------------------------------------- | |
42 | Core mark/delete routines | |
43 | ------------------------------------------------------------------------- */ | |
44 | ||
3c6c0b50 | 45 | /* True if we are invoked while the df engine is running; in this case, |
46 | we don't want to reenter it. */ | |
3072d30e | 47 | static bool df_in_progress = false; |
48 | ||
bc0dfc8d | 49 | /* True if we are allowed to alter the CFG in this pass. */ |
50 | static bool can_alter_cfg = false; | |
51 | ||
3072d30e | 52 | /* Instructions that have been marked but whose dependencies have not |
53 | yet been processed. */ | |
f1f41a6c | 54 | static vec<rtx> worklist; |
3072d30e | 55 | |
3c6c0b50 | 56 | /* Bitmap of instructions marked as needed indexed by INSN_UID. */ |
57 | static sbitmap marked; | |
58 | ||
59 | /* Bitmap obstacks used for block processing by the fast algorithm. */ | |
3072d30e | 60 | static bitmap_obstack dce_blocks_bitmap_obstack; |
61 | static bitmap_obstack dce_tmp_bitmap_obstack; | |
62 | ||
eb940a48 | 63 | static bool find_call_stack_args (rtx, bool, bool, bitmap); |
3072d30e | 64 | |
ec2fc131 | 65 | /* A subroutine for which BODY is part of the instruction being tested; |
66 | either the top-level pattern, or an element of a PARALLEL. The | |
67 | instruction is known not to be a bare USE or CLOBBER. */ | |
3072d30e | 68 | |
69 | static bool | |
ec2fc131 | 70 | deletable_insn_p_1 (rtx body) |
3072d30e | 71 | { |
d49ffcf4 | 72 | switch (GET_CODE (body)) |
3072d30e | 73 | { |
3072d30e | 74 | case PREFETCH: |
75 | case TRAP_IF: | |
76 | /* The UNSPEC case was added here because the ia-64 claims that | |
77 | USEs do not work after reload and generates UNSPECS rather | |
78 | than USEs. Since dce is run after reload we need to avoid | |
79 | deleting these even if they are dead. If it turns out that | |
80 | USEs really do work after reload, the ia-64 should be | |
81 | changed, and the UNSPEC case can be removed. */ | |
82 | case UNSPEC: | |
83 | return false; | |
84 | ||
ec2fc131 | 85 | default: |
e38def9c | 86 | return !volatile_refs_p (body); |
ec2fc131 | 87 | } |
88 | } | |
89 | ||
3c6c0b50 | 90 | |
ec2fc131 | 91 | /* Return true if INSN is a normal instruction that can be deleted by |
92 | the DCE pass. */ | |
93 | ||
94 | static bool | |
eb940a48 | 95 | deletable_insn_p (rtx insn, bool fast, bitmap arg_stores) |
ec2fc131 | 96 | { |
97 | rtx body, x; | |
98 | int i; | |
99 | ||
0b7b55ea | 100 | if (CALL_P (insn) |
101 | /* We cannot delete calls inside of the recursive dce because | |
102 | this may cause basic blocks to be deleted and this messes up | |
103 | the rest of the stack of optimization passes. */ | |
104 | && (!df_in_progress) | |
105 | /* We cannot delete pure or const sibling calls because it is | |
106 | hard to see the result. */ | |
9c2a0c05 | 107 | && (!SIBLING_CALL_P (insn)) |
0b7b55ea | 108 | /* We can delete dead const or pure calls as long as they do not |
109 | infinite loop. */ | |
9c2a0c05 | 110 | && (RTL_CONST_OR_PURE_CALL_P (insn) |
111 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
eb940a48 | 112 | return find_call_stack_args (insn, false, fast, arg_stores); |
9c2a0c05 | 113 | |
827c9a9e | 114 | /* Don't delete jumps, notes and the like. */ |
115 | if (!NONJUMP_INSN_P (insn)) | |
116 | return false; | |
117 | ||
bc0dfc8d | 118 | /* Don't delete insns that may throw if we cannot do so. */ |
119 | if (!(cfun->can_delete_dead_exceptions && can_alter_cfg) | |
120 | && !insn_nothrow_p (insn)) | |
827c9a9e | 121 | return false; |
122 | ||
925e8609 | 123 | /* If INSN sets a global_reg, leave it untouched. */ |
124 | for (df_ref *def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++) | |
125 | if (HARD_REGISTER_NUM_P (DF_REF_REGNO (*def_rec)) | |
126 | && global_regs[DF_REF_REGNO (*def_rec)]) | |
127 | return false; | |
128 | ||
ec2fc131 | 129 | body = PATTERN (insn); |
130 | switch (GET_CODE (body)) | |
131 | { | |
132 | case USE: | |
9845d120 | 133 | case VAR_LOCATION: |
ec2fc131 | 134 | return false; |
135 | ||
3072d30e | 136 | case CLOBBER: |
137 | if (fast) | |
138 | { | |
139 | /* A CLOBBER of a dead pseudo register serves no purpose. | |
140 | That is not necessarily true for hard registers until | |
141 | after reload. */ | |
d49ffcf4 | 142 | x = XEXP (body, 0); |
3072d30e | 143 | return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed); |
144 | } | |
ec2fc131 | 145 | else |
3072d30e | 146 | /* Because of the way that use-def chains are built, it is not |
147 | possible to tell if the clobber is dead because it can | |
148 | never be the target of a use-def chain. */ | |
149 | return false; | |
150 | ||
d49ffcf4 | 151 | case PARALLEL: |
ec2fc131 | 152 | for (i = XVECLEN (body, 0) - 1; i >= 0; i--) |
153 | if (!deletable_insn_p_1 (XVECEXP (body, 0, i))) | |
154 | return false; | |
155 | return true; | |
d49ffcf4 | 156 | |
3072d30e | 157 | default: |
ec2fc131 | 158 | return deletable_insn_p_1 (body); |
3072d30e | 159 | } |
160 | } | |
161 | ||
162 | ||
3c6c0b50 | 163 | /* Return true if INSN has been marked as needed. */ |
3072d30e | 164 | |
165 | static inline int | |
166 | marked_insn_p (rtx insn) | |
167 | { | |
158b6cc9 | 168 | /* Artificial defs are always needed and they do not have an insn. |
169 | We should never see them here. */ | |
170 | gcc_assert (insn); | |
08b7917c | 171 | return bitmap_bit_p (marked, INSN_UID (insn)); |
3072d30e | 172 | } |
173 | ||
174 | ||
175 | /* If INSN has not yet been marked as needed, mark it now, and add it to | |
176 | the worklist. */ | |
177 | ||
178 | static void | |
179 | mark_insn (rtx insn, bool fast) | |
180 | { | |
181 | if (!marked_insn_p (insn)) | |
182 | { | |
183 | if (!fast) | |
f1f41a6c | 184 | worklist.safe_push (insn); |
08b7917c | 185 | bitmap_set_bit (marked, INSN_UID (insn)); |
3072d30e | 186 | if (dump_file) |
187 | fprintf (dump_file, " Adding insn %d to worklist\n", INSN_UID (insn)); | |
eb940a48 | 188 | if (CALL_P (insn) |
189 | && !df_in_progress | |
190 | && !SIBLING_CALL_P (insn) | |
191 | && (RTL_CONST_OR_PURE_CALL_P (insn) | |
192 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
193 | find_call_stack_args (insn, true, fast, NULL); | |
3072d30e | 194 | } |
195 | } | |
196 | ||
197 | ||
198 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
199 | instruction containing DEST. */ | |
200 | ||
201 | static void | |
81a410b1 | 202 | mark_nonreg_stores_1 (rtx dest, const_rtx pattern, void *data) |
3072d30e | 203 | { |
204 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
205 | mark_insn ((rtx) data, true); | |
206 | } | |
207 | ||
208 | ||
209 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
210 | instruction containing DEST. */ | |
211 | ||
212 | static void | |
81a410b1 | 213 | mark_nonreg_stores_2 (rtx dest, const_rtx pattern, void *data) |
3072d30e | 214 | { |
215 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
216 | mark_insn ((rtx) data, false); | |
217 | } | |
218 | ||
219 | ||
220 | /* Mark INSN if BODY stores to a non-register destination. */ | |
221 | ||
222 | static void | |
223 | mark_nonreg_stores (rtx body, rtx insn, bool fast) | |
224 | { | |
225 | if (fast) | |
226 | note_stores (body, mark_nonreg_stores_1, insn); | |
227 | else | |
228 | note_stores (body, mark_nonreg_stores_2, insn); | |
229 | } | |
230 | ||
231 | ||
85e2842b | 232 | /* Return true if store to MEM, starting OFF bytes from stack pointer, |
233 | is a call argument store, and clear corresponding bits from SP_BYTES | |
234 | bitmap if it is. */ | |
235 | ||
236 | static bool | |
237 | check_argument_store (rtx mem, HOST_WIDE_INT off, HOST_WIDE_INT min_sp_off, | |
238 | HOST_WIDE_INT max_sp_off, bitmap sp_bytes) | |
239 | { | |
240 | HOST_WIDE_INT byte; | |
241 | for (byte = off; byte < off + GET_MODE_SIZE (GET_MODE (mem)); byte++) | |
242 | { | |
243 | if (byte < min_sp_off | |
244 | || byte >= max_sp_off | |
245 | || !bitmap_clear_bit (sp_bytes, byte - min_sp_off)) | |
246 | return false; | |
247 | } | |
248 | return true; | |
249 | } | |
250 | ||
251 | ||
eb940a48 | 252 | /* Try to find all stack stores of CALL_INSN arguments if |
253 | ACCUMULATE_OUTGOING_ARGS. If all stack stores have been found | |
254 | and it is therefore safe to eliminate the call, return true, | |
255 | otherwise return false. This function should be first called | |
256 | with DO_MARK false, and only when the CALL_INSN is actually | |
257 | going to be marked called again with DO_MARK true. */ | |
258 | ||
259 | static bool | |
260 | find_call_stack_args (rtx call_insn, bool do_mark, bool fast, | |
261 | bitmap arg_stores) | |
262 | { | |
263 | rtx p, insn, prev_insn; | |
264 | bool ret; | |
265 | HOST_WIDE_INT min_sp_off, max_sp_off; | |
266 | bitmap sp_bytes; | |
267 | ||
268 | gcc_assert (CALL_P (call_insn)); | |
269 | if (!ACCUMULATE_OUTGOING_ARGS) | |
270 | return true; | |
271 | ||
272 | if (!do_mark) | |
273 | { | |
274 | gcc_assert (arg_stores); | |
275 | bitmap_clear (arg_stores); | |
276 | } | |
277 | ||
278 | min_sp_off = INTTYPE_MAXIMUM (HOST_WIDE_INT); | |
279 | max_sp_off = 0; | |
280 | ||
281 | /* First determine the minimum and maximum offset from sp for | |
282 | stored arguments. */ | |
283 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
284 | if (GET_CODE (XEXP (p, 0)) == USE | |
285 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
286 | { | |
5b2a69fa | 287 | rtx mem = XEXP (XEXP (p, 0), 0), addr; |
288 | HOST_WIDE_INT off = 0, size; | |
289 | if (!MEM_SIZE_KNOWN_P (mem)) | |
eb940a48 | 290 | return false; |
5b2a69fa | 291 | size = MEM_SIZE (mem); |
eb940a48 | 292 | addr = XEXP (mem, 0); |
293 | if (GET_CODE (addr) == PLUS | |
294 | && REG_P (XEXP (addr, 0)) | |
295 | && CONST_INT_P (XEXP (addr, 1))) | |
296 | { | |
297 | off = INTVAL (XEXP (addr, 1)); | |
298 | addr = XEXP (addr, 0); | |
299 | } | |
300 | if (addr != stack_pointer_rtx) | |
301 | { | |
302 | if (!REG_P (addr)) | |
303 | return false; | |
304 | /* If not fast, use chains to see if addr wasn't set to | |
305 | sp + offset. */ | |
306 | if (!fast) | |
307 | { | |
308 | df_ref *use_rec; | |
309 | struct df_link *defs; | |
310 | rtx set; | |
311 | ||
312 | for (use_rec = DF_INSN_USES (call_insn); *use_rec; use_rec++) | |
313 | if (rtx_equal_p (addr, DF_REF_REG (*use_rec))) | |
314 | break; | |
315 | ||
316 | if (*use_rec == NULL) | |
317 | return false; | |
318 | ||
319 | for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next) | |
320 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) | |
321 | break; | |
322 | ||
323 | if (defs == NULL) | |
324 | return false; | |
325 | ||
326 | set = single_set (DF_REF_INSN (defs->ref)); | |
327 | if (!set) | |
328 | return false; | |
329 | ||
330 | if (GET_CODE (SET_SRC (set)) != PLUS | |
331 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
332 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
333 | return false; | |
334 | ||
335 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
336 | } | |
337 | else | |
338 | return false; | |
339 | } | |
340 | min_sp_off = MIN (min_sp_off, off); | |
5b2a69fa | 341 | max_sp_off = MAX (max_sp_off, off + size); |
eb940a48 | 342 | } |
343 | ||
344 | if (min_sp_off >= max_sp_off) | |
345 | return true; | |
346 | sp_bytes = BITMAP_ALLOC (NULL); | |
347 | ||
348 | /* Set bits in SP_BYTES bitmap for bytes relative to sp + min_sp_off | |
349 | which contain arguments. Checking has been done in the previous | |
350 | loop. */ | |
351 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
352 | if (GET_CODE (XEXP (p, 0)) == USE | |
353 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
354 | { | |
355 | rtx mem = XEXP (XEXP (p, 0), 0), addr; | |
356 | HOST_WIDE_INT off = 0, byte; | |
357 | addr = XEXP (mem, 0); | |
358 | if (GET_CODE (addr) == PLUS | |
359 | && REG_P (XEXP (addr, 0)) | |
360 | && CONST_INT_P (XEXP (addr, 1))) | |
361 | { | |
362 | off = INTVAL (XEXP (addr, 1)); | |
363 | addr = XEXP (addr, 0); | |
364 | } | |
365 | if (addr != stack_pointer_rtx) | |
366 | { | |
367 | df_ref *use_rec; | |
368 | struct df_link *defs; | |
369 | rtx set; | |
370 | ||
371 | for (use_rec = DF_INSN_USES (call_insn); *use_rec; use_rec++) | |
372 | if (rtx_equal_p (addr, DF_REF_REG (*use_rec))) | |
373 | break; | |
374 | ||
375 | for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next) | |
376 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) | |
377 | break; | |
378 | ||
379 | set = single_set (DF_REF_INSN (defs->ref)); | |
380 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
381 | } | |
5b2a69fa | 382 | for (byte = off; byte < off + MEM_SIZE (mem); byte++) |
eb940a48 | 383 | { |
2adb8813 | 384 | if (!bitmap_set_bit (sp_bytes, byte - min_sp_off)) |
385 | gcc_unreachable (); | |
eb940a48 | 386 | } |
387 | } | |
388 | ||
389 | /* Walk backwards, looking for argument stores. The search stops | |
66aca59d | 390 | when seeing another call, sp adjustment or memory store other than |
eb940a48 | 391 | argument store. */ |
392 | ret = false; | |
393 | for (insn = PREV_INSN (call_insn); insn; insn = prev_insn) | |
394 | { | |
395 | rtx set, mem, addr; | |
85e2842b | 396 | HOST_WIDE_INT off; |
eb940a48 | 397 | |
398 | if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn))) | |
399 | prev_insn = NULL_RTX; | |
400 | else | |
401 | prev_insn = PREV_INSN (insn); | |
402 | ||
403 | if (CALL_P (insn)) | |
404 | break; | |
405 | ||
85e2842b | 406 | if (!NONDEBUG_INSN_P (insn)) |
eb940a48 | 407 | continue; |
408 | ||
409 | set = single_set (insn); | |
410 | if (!set || SET_DEST (set) == stack_pointer_rtx) | |
411 | break; | |
412 | ||
413 | if (!MEM_P (SET_DEST (set))) | |
414 | continue; | |
415 | ||
416 | mem = SET_DEST (set); | |
417 | addr = XEXP (mem, 0); | |
418 | off = 0; | |
419 | if (GET_CODE (addr) == PLUS | |
420 | && REG_P (XEXP (addr, 0)) | |
421 | && CONST_INT_P (XEXP (addr, 1))) | |
422 | { | |
423 | off = INTVAL (XEXP (addr, 1)); | |
424 | addr = XEXP (addr, 0); | |
425 | } | |
426 | if (addr != stack_pointer_rtx) | |
427 | { | |
428 | if (!REG_P (addr)) | |
429 | break; | |
430 | if (!fast) | |
431 | { | |
432 | df_ref *use_rec; | |
433 | struct df_link *defs; | |
434 | rtx set; | |
435 | ||
436 | for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++) | |
437 | if (rtx_equal_p (addr, DF_REF_REG (*use_rec))) | |
438 | break; | |
439 | ||
440 | if (*use_rec == NULL) | |
441 | break; | |
442 | ||
443 | for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next) | |
444 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) | |
445 | break; | |
446 | ||
447 | if (defs == NULL) | |
448 | break; | |
449 | ||
450 | set = single_set (DF_REF_INSN (defs->ref)); | |
451 | if (!set) | |
452 | break; | |
453 | ||
454 | if (GET_CODE (SET_SRC (set)) != PLUS | |
455 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
456 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
457 | break; | |
458 | ||
459 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
460 | } | |
461 | else | |
462 | break; | |
463 | } | |
464 | ||
85e2842b | 465 | if (GET_MODE_SIZE (GET_MODE (mem)) == 0 |
466 | || !check_argument_store (mem, off, min_sp_off, | |
467 | max_sp_off, sp_bytes)) | |
eb940a48 | 468 | break; |
469 | ||
eb940a48 | 470 | if (!deletable_insn_p (insn, fast, NULL)) |
471 | break; | |
472 | ||
473 | if (do_mark) | |
474 | mark_insn (insn, fast); | |
475 | else | |
476 | bitmap_set_bit (arg_stores, INSN_UID (insn)); | |
477 | ||
478 | if (bitmap_empty_p (sp_bytes)) | |
479 | { | |
480 | ret = true; | |
481 | break; | |
482 | } | |
483 | } | |
484 | ||
485 | BITMAP_FREE (sp_bytes); | |
486 | if (!ret && arg_stores) | |
487 | bitmap_clear (arg_stores); | |
488 | ||
489 | return ret; | |
490 | } | |
491 | ||
492 | ||
09669349 | 493 | /* Remove all REG_EQUAL and REG_EQUIV notes referring to the registers INSN |
494 | writes to. */ | |
3072d30e | 495 | |
496 | static void | |
09669349 | 497 | remove_reg_equal_equiv_notes_for_defs (rtx insn) |
3072d30e | 498 | { |
ed6e85ae | 499 | df_ref *def_rec; |
09669349 | 500 | |
3072d30e | 501 | for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++) |
09669349 | 502 | remove_reg_equal_equiv_notes_for_regno (DF_REF_REGNO (*def_rec)); |
3072d30e | 503 | } |
504 | ||
a6aa49aa | 505 | /* Scan all BBs for debug insns and reset those that reference values |
506 | defined in unmarked insns. */ | |
507 | ||
508 | static void | |
509 | reset_unmarked_insns_debug_uses (void) | |
510 | { | |
511 | basic_block bb; | |
512 | rtx insn, next; | |
513 | ||
514 | FOR_EACH_BB_REVERSE (bb) | |
515 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) | |
516 | if (DEBUG_INSN_P (insn)) | |
517 | { | |
518 | df_ref *use_rec; | |
519 | ||
520 | for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++) | |
521 | { | |
522 | df_ref use = *use_rec; | |
523 | struct df_link *defs; | |
524 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
525 | { | |
5af2c7fc | 526 | rtx ref_insn; |
a6aa49aa | 527 | if (DF_REF_IS_ARTIFICIAL (defs->ref)) |
528 | continue; | |
5af2c7fc | 529 | ref_insn = DF_REF_INSN (defs->ref); |
530 | if (!marked_insn_p (ref_insn)) | |
a6aa49aa | 531 | break; |
532 | } | |
533 | if (!defs) | |
534 | continue; | |
535 | /* ??? FIXME could we propagate the values assigned to | |
536 | each of the DEFs? */ | |
537 | INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC (); | |
538 | df_insn_rescan_debug_internal (insn); | |
5af2c7fc | 539 | break; |
a6aa49aa | 540 | } |
541 | } | |
542 | } | |
3072d30e | 543 | |
ebc94641 | 544 | /* Delete every instruction that hasn't been marked. */ |
3072d30e | 545 | |
546 | static void | |
547 | delete_unmarked_insns (void) | |
548 | { | |
549 | basic_block bb; | |
550 | rtx insn, next; | |
0b7b55ea | 551 | bool must_clean = false; |
3072d30e | 552 | |
cff725a2 | 553 | FOR_EACH_BB_REVERSE (bb) |
554 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) | |
a6aa49aa | 555 | if (NONDEBUG_INSN_P (insn)) |
3072d30e | 556 | { |
ebc94641 | 557 | /* Always delete no-op moves. */ |
3072d30e | 558 | if (noop_move_p (insn)) |
ebc94641 | 559 | ; |
560 | ||
ebc94641 | 561 | /* Otherwise rely only on the DCE algorithm. */ |
3072d30e | 562 | else if (marked_insn_p (insn)) |
563 | continue; | |
564 | ||
cff725a2 | 565 | /* Beware that reaching a dbg counter limit here can result |
566 | in miscompiled file. This occurs when a group of insns | |
567 | must be deleted together, typically because the kept insn | |
568 | depends on the output from the deleted insn. Deleting | |
569 | this insns in reverse order (both at the bb level and | |
570 | when looking at the blocks) minimizes this, but does not | |
571 | eliminate it, since it is possible for the using insn to | |
572 | be top of a block and the producer to be at the bottom of | |
573 | the block. However, in most cases this will only result | |
574 | in an uninitialized use of an insn that is dead anyway. | |
575 | ||
576 | However, there is one rare case that will cause a | |
577 | miscompile: deletion of non-looping pure and constant | |
578 | calls on a machine where ACCUMULATE_OUTGOING_ARGS is true. | |
579 | In this case it is possible to remove the call, but leave | |
580 | the argument pushes to the stack. Because of the changes | |
581 | to the stack pointer, this will almost always lead to a | |
582 | miscompile. */ | |
3072d30e | 583 | if (!dbg_cnt (dce)) |
584 | continue; | |
585 | ||
586 | if (dump_file) | |
587 | fprintf (dump_file, "DCE: Deleting insn %d\n", INSN_UID (insn)); | |
588 | ||
09669349 | 589 | /* Before we delete the insn we have to remove the REG_EQUAL notes |
ebc94641 | 590 | for the destination regs in order to avoid dangling notes. */ |
09669349 | 591 | remove_reg_equal_equiv_notes_for_defs (insn); |
3072d30e | 592 | |
0b7b55ea | 593 | /* If a pure or const call is deleted, this may make the cfg |
594 | have unreachable blocks. We rememeber this and call | |
595 | delete_unreachable_blocks at the end. */ | |
596 | if (CALL_P (insn)) | |
597 | must_clean = true; | |
598 | ||
ebc94641 | 599 | /* Now delete the insn. */ |
3072d30e | 600 | delete_insn_and_edges (insn); |
3072d30e | 601 | } |
0b7b55ea | 602 | |
603 | /* Deleted a pure or const call. */ | |
604 | if (must_clean) | |
605 | delete_unreachable_blocks (); | |
3072d30e | 606 | } |
607 | ||
608 | ||
3072d30e | 609 | /* Go through the instructions and mark those whose necessity is not |
610 | dependent on inter-instruction information. Make sure all other | |
611 | instructions are not marked. */ | |
612 | ||
613 | static void | |
614 | prescan_insns_for_dce (bool fast) | |
615 | { | |
616 | basic_block bb; | |
eb940a48 | 617 | rtx insn, prev; |
618 | bitmap arg_stores = NULL; | |
619 | ||
3072d30e | 620 | if (dump_file) |
621 | fprintf (dump_file, "Finding needed instructions:\n"); | |
eb940a48 | 622 | |
623 | if (!df_in_progress && ACCUMULATE_OUTGOING_ARGS) | |
624 | arg_stores = BITMAP_ALLOC (NULL); | |
625 | ||
3072d30e | 626 | FOR_EACH_BB (bb) |
eb940a48 | 627 | { |
628 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev) | |
a6aa49aa | 629 | if (NONDEBUG_INSN_P (insn)) |
eb940a48 | 630 | { |
631 | /* Don't mark argument stores now. They will be marked | |
632 | if needed when the associated CALL is marked. */ | |
633 | if (arg_stores && bitmap_bit_p (arg_stores, INSN_UID (insn))) | |
634 | continue; | |
635 | if (deletable_insn_p (insn, fast, arg_stores)) | |
636 | mark_nonreg_stores (PATTERN (insn), insn, fast); | |
637 | else | |
638 | mark_insn (insn, fast); | |
639 | } | |
640 | /* find_call_stack_args only looks at argument stores in the | |
641 | same bb. */ | |
642 | if (arg_stores) | |
643 | bitmap_clear (arg_stores); | |
644 | } | |
645 | ||
646 | if (arg_stores) | |
647 | BITMAP_FREE (arg_stores); | |
3072d30e | 648 | |
649 | if (dump_file) | |
650 | fprintf (dump_file, "Finished finding needed instructions:\n"); | |
651 | } | |
652 | ||
653 | ||
654 | /* UD-based DSE routines. */ | |
655 | ||
6dfdc153 | 656 | /* Mark instructions that define artificially-used registers, such as |
3072d30e | 657 | the frame pointer and the stack pointer. */ |
658 | ||
659 | static void | |
660 | mark_artificial_uses (void) | |
661 | { | |
662 | basic_block bb; | |
663 | struct df_link *defs; | |
ed6e85ae | 664 | df_ref *use_rec; |
3072d30e | 665 | |
666 | FOR_ALL_BB (bb) | |
667 | { | |
48e1416a | 668 | for (use_rec = df_get_artificial_uses (bb->index); |
3072d30e | 669 | *use_rec; use_rec++) |
670 | for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next) | |
158b6cc9 | 671 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
672 | mark_insn (DF_REF_INSN (defs->ref), false); | |
3072d30e | 673 | } |
674 | } | |
675 | ||
3c6c0b50 | 676 | |
3072d30e | 677 | /* Mark every instruction that defines a register value that INSN uses. */ |
678 | ||
679 | static void | |
680 | mark_reg_dependencies (rtx insn) | |
681 | { | |
682 | struct df_link *defs; | |
ed6e85ae | 683 | df_ref *use_rec; |
3072d30e | 684 | |
9845d120 | 685 | if (DEBUG_INSN_P (insn)) |
686 | return; | |
687 | ||
3072d30e | 688 | for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++) |
689 | { | |
ed6e85ae | 690 | df_ref use = *use_rec; |
3072d30e | 691 | if (dump_file) |
692 | { | |
693 | fprintf (dump_file, "Processing use of "); | |
694 | print_simple_rtl (dump_file, DF_REF_REG (use)); | |
695 | fprintf (dump_file, " in insn %d:\n", INSN_UID (insn)); | |
696 | } | |
697 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
158b6cc9 | 698 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
699 | mark_insn (DF_REF_INSN (defs->ref), false); | |
3072d30e | 700 | } |
701 | } | |
702 | ||
703 | ||
3c6c0b50 | 704 | /* Initialize global variables for a new DCE pass. */ |
705 | ||
3072d30e | 706 | static void |
3c6c0b50 | 707 | init_dce (bool fast) |
708 | { | |
709 | if (!df_in_progress) | |
710 | { | |
711 | if (!fast) | |
ea9538fb | 712 | { |
713 | df_set_flags (DF_RD_PRUNE_DEAD_DEFS); | |
714 | df_chain_add_problem (DF_UD_CHAIN); | |
715 | } | |
3c6c0b50 | 716 | df_analyze (); |
717 | } | |
718 | ||
719 | if (dump_file) | |
720 | df_dump (dump_file); | |
721 | ||
722 | if (fast) | |
723 | { | |
724 | bitmap_obstack_initialize (&dce_blocks_bitmap_obstack); | |
725 | bitmap_obstack_initialize (&dce_tmp_bitmap_obstack); | |
bc0dfc8d | 726 | can_alter_cfg = false; |
3c6c0b50 | 727 | } |
bc0dfc8d | 728 | else |
729 | can_alter_cfg = true; | |
3c6c0b50 | 730 | |
731 | marked = sbitmap_alloc (get_max_uid () + 1); | |
53c5d9d4 | 732 | bitmap_clear (marked); |
3c6c0b50 | 733 | } |
734 | ||
735 | ||
736 | /* Free the data allocated by init_dce. */ | |
737 | ||
738 | static void | |
739 | fini_dce (bool fast) | |
3072d30e | 740 | { |
741 | sbitmap_free (marked); | |
3c6c0b50 | 742 | |
743 | if (fast) | |
744 | { | |
745 | bitmap_obstack_release (&dce_blocks_bitmap_obstack); | |
746 | bitmap_obstack_release (&dce_tmp_bitmap_obstack); | |
747 | } | |
3072d30e | 748 | } |
749 | ||
750 | ||
751 | /* UD-chain based DCE. */ | |
752 | ||
753 | static unsigned int | |
754 | rest_of_handle_ud_dce (void) | |
755 | { | |
756 | rtx insn; | |
757 | ||
3072d30e | 758 | init_dce (false); |
759 | ||
760 | prescan_insns_for_dce (false); | |
761 | mark_artificial_uses (); | |
f1f41a6c | 762 | while (worklist.length () > 0) |
3072d30e | 763 | { |
f1f41a6c | 764 | insn = worklist.pop (); |
3072d30e | 765 | mark_reg_dependencies (insn); |
766 | } | |
f1f41a6c | 767 | worklist.release (); |
3c6c0b50 | 768 | |
a6aa49aa | 769 | if (MAY_HAVE_DEBUG_INSNS) |
770 | reset_unmarked_insns_debug_uses (); | |
771 | ||
3072d30e | 772 | /* Before any insns are deleted, we must remove the chains since |
773 | they are not bidirectional. */ | |
774 | df_remove_problem (df_chain); | |
775 | delete_unmarked_insns (); | |
776 | ||
3c6c0b50 | 777 | fini_dce (false); |
3072d30e | 778 | return 0; |
779 | } | |
780 | ||
781 | ||
782 | static bool | |
783 | gate_ud_dce (void) | |
784 | { | |
4ff06051 | 785 | return optimize > 1 && flag_dce |
786 | && dbg_cnt (dce_ud); | |
3072d30e | 787 | } |
788 | ||
cbe8bda8 | 789 | namespace { |
790 | ||
791 | const pass_data pass_data_ud_rtl_dce = | |
3072d30e | 792 | { |
cbe8bda8 | 793 | RTL_PASS, /* type */ |
794 | "ud_dce", /* name */ | |
795 | OPTGROUP_NONE, /* optinfo_flags */ | |
796 | true, /* has_gate */ | |
797 | true, /* has_execute */ | |
798 | TV_DCE, /* tv_id */ | |
799 | 0, /* properties_required */ | |
800 | 0, /* properties_provided */ | |
801 | 0, /* properties_destroyed */ | |
802 | 0, /* todo_flags_start */ | |
803 | ( TODO_df_finish | TODO_verify_rtl_sharing ), /* todo_flags_finish */ | |
3072d30e | 804 | }; |
805 | ||
cbe8bda8 | 806 | class pass_ud_rtl_dce : public rtl_opt_pass |
807 | { | |
808 | public: | |
809 | pass_ud_rtl_dce(gcc::context *ctxt) | |
810 | : rtl_opt_pass(pass_data_ud_rtl_dce, ctxt) | |
811 | {} | |
812 | ||
813 | /* opt_pass methods: */ | |
814 | bool gate () { return gate_ud_dce (); } | |
815 | unsigned int execute () { return rest_of_handle_ud_dce (); } | |
816 | ||
817 | }; // class pass_ud_rtl_dce | |
818 | ||
819 | } // anon namespace | |
820 | ||
821 | rtl_opt_pass * | |
822 | make_pass_ud_rtl_dce (gcc::context *ctxt) | |
823 | { | |
824 | return new pass_ud_rtl_dce (ctxt); | |
825 | } | |
826 | ||
3c6c0b50 | 827 | |
3072d30e | 828 | /* ------------------------------------------------------------------------- |
829 | Fast DCE functions | |
830 | ------------------------------------------------------------------------- */ | |
831 | ||
bf1f8fbc | 832 | /* Process basic block BB. Return true if the live_in set has |
833 | changed. REDO_OUT is true if the info at the bottom of the block | |
834 | needs to be recalculated before starting. AU is the proper set of | |
dcd028e1 | 835 | artificial uses. Track global substitution of uses of dead pseudos |
836 | in debug insns using GLOBAL_DEBUG. */ | |
3072d30e | 837 | |
838 | static bool | |
dcd028e1 | 839 | word_dce_process_block (basic_block bb, bool redo_out, |
840 | struct dead_debug_global *global_debug) | |
3072d30e | 841 | { |
842 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
843 | rtx insn; | |
844 | bool block_changed; | |
dcd028e1 | 845 | struct dead_debug_local debug; |
3072d30e | 846 | |
847 | if (redo_out) | |
848 | { | |
849 | /* Need to redo the live_out set of this block if when one of | |
850 | the succs of this block has had a change in it live in | |
851 | set. */ | |
852 | edge e; | |
853 | edge_iterator ei; | |
0e8e9be3 | 854 | df_confluence_function_n con_fun_n = df_word_lr->problem->con_fun_n; |
855 | bitmap_clear (DF_WORD_LR_OUT (bb)); | |
3072d30e | 856 | FOR_EACH_EDGE (e, ei, bb->succs) |
857 | (*con_fun_n) (e); | |
858 | } | |
859 | ||
860 | if (dump_file) | |
861 | { | |
862 | fprintf (dump_file, "processing block %d live out = ", bb->index); | |
0e8e9be3 | 863 | df_print_word_regset (dump_file, DF_WORD_LR_OUT (bb)); |
3072d30e | 864 | } |
865 | ||
0e8e9be3 | 866 | bitmap_copy (local_live, DF_WORD_LR_OUT (bb)); |
dcd028e1 | 867 | dead_debug_local_init (&debug, NULL, global_debug); |
bf1f8fbc | 868 | |
869 | FOR_BB_INSNS_REVERSE (bb, insn) | |
2abb79fc | 870 | if (DEBUG_INSN_P (insn)) |
871 | { | |
872 | df_ref *use_rec; | |
873 | for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++) | |
874 | if (DF_REF_REGNO (*use_rec) >= FIRST_PSEUDO_REGISTER | |
875 | && (GET_MODE_SIZE (GET_MODE (DF_REF_REAL_REG (*use_rec))) | |
876 | == 2 * UNITS_PER_WORD) | |
877 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (*use_rec)) | |
878 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (*use_rec) + 1)) | |
f84542f4 | 879 | dead_debug_add (&debug, *use_rec, DF_REF_REGNO (*use_rec)); |
2abb79fc | 880 | } |
881 | else if (INSN_P (insn)) | |
bf1f8fbc | 882 | { |
0e8e9be3 | 883 | bool any_changed; |
2abb79fc | 884 | |
bf1f8fbc | 885 | /* No matter if the instruction is needed or not, we remove |
886 | any regno in the defs from the live set. */ | |
0e8e9be3 | 887 | any_changed = df_word_lr_simulate_defs (insn, local_live); |
888 | if (any_changed) | |
889 | mark_insn (insn, true); | |
bf1f8fbc | 890 | |
891 | /* On the other hand, we do not allow the dead uses to set | |
892 | anything in local_live. */ | |
893 | if (marked_insn_p (insn)) | |
0e8e9be3 | 894 | df_word_lr_simulate_uses (insn, local_live); |
704e91bd | 895 | |
5ea3fd4b | 896 | /* Insert debug temps for dead REGs used in subsequent debug |
704e91bd | 897 | insns. We may have to emit a debug temp even if the insn |
898 | was marked, in case the debug use was after the point of | |
899 | death. */ | |
900 | if (debug.used && !bitmap_empty_p (debug.used)) | |
2abb79fc | 901 | { |
902 | df_ref *def_rec; | |
903 | ||
904 | for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++) | |
905 | dead_debug_insert_temp (&debug, DF_REF_REGNO (*def_rec), insn, | |
6baa953c | 906 | marked_insn_p (insn) |
907 | && !control_flow_insn_p (insn) | |
908 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
909 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
2abb79fc | 910 | } |
911 | ||
bf1f8fbc | 912 | if (dump_file) |
913 | { | |
48e1416a | 914 | fprintf (dump_file, "finished processing insn %d live out = ", |
bf1f8fbc | 915 | INSN_UID (insn)); |
0e8e9be3 | 916 | df_print_word_regset (dump_file, local_live); |
bf1f8fbc | 917 | } |
918 | } | |
48e1416a | 919 | |
0e8e9be3 | 920 | block_changed = !bitmap_equal_p (local_live, DF_WORD_LR_IN (bb)); |
bf1f8fbc | 921 | if (block_changed) |
0e8e9be3 | 922 | bitmap_copy (DF_WORD_LR_IN (bb), local_live); |
923 | ||
dcd028e1 | 924 | dead_debug_local_finish (&debug, NULL); |
bf1f8fbc | 925 | BITMAP_FREE (local_live); |
926 | return block_changed; | |
927 | } | |
928 | ||
929 | ||
930 | /* Process basic block BB. Return true if the live_in set has | |
931 | changed. REDO_OUT is true if the info at the bottom of the block | |
932 | needs to be recalculated before starting. AU is the proper set of | |
dcd028e1 | 933 | artificial uses. Track global substitution of uses of dead pseudos |
934 | in debug insns using GLOBAL_DEBUG. */ | |
bf1f8fbc | 935 | |
936 | static bool | |
dcd028e1 | 937 | dce_process_block (basic_block bb, bool redo_out, bitmap au, |
938 | struct dead_debug_global *global_debug) | |
bf1f8fbc | 939 | { |
940 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
941 | rtx insn; | |
942 | bool block_changed; | |
ed6e85ae | 943 | df_ref *def_rec; |
dcd028e1 | 944 | struct dead_debug_local debug; |
3072d30e | 945 | |
bf1f8fbc | 946 | if (redo_out) |
3072d30e | 947 | { |
bf1f8fbc | 948 | /* Need to redo the live_out set of this block if when one of |
949 | the succs of this block has had a change in it live in | |
950 | set. */ | |
951 | edge e; | |
952 | edge_iterator ei; | |
953 | df_confluence_function_n con_fun_n = df_lr->problem->con_fun_n; | |
954 | bitmap_clear (DF_LR_OUT (bb)); | |
955 | FOR_EACH_EDGE (e, ei, bb->succs) | |
956 | (*con_fun_n) (e); | |
3072d30e | 957 | } |
958 | ||
bf1f8fbc | 959 | if (dump_file) |
3072d30e | 960 | { |
7e009ff5 | 961 | fprintf (dump_file, "processing block %d lr out = ", bb->index); |
bf1f8fbc | 962 | df_print_regset (dump_file, DF_LR_OUT (bb)); |
3072d30e | 963 | } |
964 | ||
bf1f8fbc | 965 | bitmap_copy (local_live, DF_LR_OUT (bb)); |
966 | ||
a1b0a968 | 967 | df_simulate_initialize_backwards (bb, local_live); |
dcd028e1 | 968 | dead_debug_local_init (&debug, NULL, global_debug); |
011634f2 | 969 | |
3072d30e | 970 | FOR_BB_INSNS_REVERSE (bb, insn) |
2abb79fc | 971 | if (DEBUG_INSN_P (insn)) |
972 | { | |
973 | df_ref *use_rec; | |
974 | for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++) | |
975 | if (!bitmap_bit_p (local_live, DF_REF_REGNO (*use_rec)) | |
976 | && !bitmap_bit_p (au, DF_REF_REGNO (*use_rec))) | |
f84542f4 | 977 | dead_debug_add (&debug, *use_rec, DF_REF_REGNO (*use_rec)); |
2abb79fc | 978 | } |
979 | else if (INSN_P (insn)) | |
3072d30e | 980 | { |
cbc39d5b | 981 | bool needed = marked_insn_p (insn); |
ebc94641 | 982 | |
983 | /* The insn is needed if there is someone who uses the output. */ | |
cbc39d5b | 984 | if (!needed) |
985 | for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++) | |
5ea3fd4b | 986 | if (bitmap_bit_p (local_live, DF_REF_REGNO (*def_rec)) |
987 | || bitmap_bit_p (au, DF_REF_REGNO (*def_rec))) | |
988 | { | |
989 | needed = true; | |
990 | mark_insn (insn, true); | |
991 | break; | |
992 | } | |
48e1416a | 993 | |
3072d30e | 994 | /* No matter if the instruction is needed or not, we remove |
995 | any regno in the defs from the live set. */ | |
996 | df_simulate_defs (insn, local_live); | |
997 | ||
998 | /* On the other hand, we do not allow the dead uses to set | |
999 | anything in local_live. */ | |
cbc39d5b | 1000 | if (needed) |
3072d30e | 1001 | df_simulate_uses (insn, local_live); |
704e91bd | 1002 | |
5ea3fd4b | 1003 | /* Insert debug temps for dead REGs used in subsequent debug |
704e91bd | 1004 | insns. We may have to emit a debug temp even if the insn |
1005 | was marked, in case the debug use was after the point of | |
1006 | death. */ | |
1007 | if (debug.used && !bitmap_empty_p (debug.used)) | |
5ea3fd4b | 1008 | for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++) |
1009 | dead_debug_insert_temp (&debug, DF_REF_REGNO (*def_rec), insn, | |
6baa953c | 1010 | needed && !control_flow_insn_p (insn) |
1011 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
1012 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
3072d30e | 1013 | } |
48e1416a | 1014 | |
dcd028e1 | 1015 | dead_debug_local_finish (&debug, NULL); |
a1b0a968 | 1016 | df_simulate_finalize_backwards (bb, local_live); |
3072d30e | 1017 | |
1018 | block_changed = !bitmap_equal_p (local_live, DF_LR_IN (bb)); | |
1019 | if (block_changed) | |
1020 | bitmap_copy (DF_LR_IN (bb), local_live); | |
1021 | ||
1022 | BITMAP_FREE (local_live); | |
1023 | return block_changed; | |
1024 | } | |
1025 | ||
3c6c0b50 | 1026 | |
0e8e9be3 | 1027 | /* Perform fast DCE once initialization is done. If WORD_LEVEL is |
1028 | true, use the word level dce, otherwise do it at the pseudo | |
bf1f8fbc | 1029 | level. */ |
3c6c0b50 | 1030 | |
3072d30e | 1031 | static void |
0e8e9be3 | 1032 | fast_dce (bool word_level) |
3072d30e | 1033 | { |
1034 | int *postorder = df_get_postorder (DF_BACKWARD); | |
1035 | int n_blocks = df_get_n_blocks (DF_BACKWARD); | |
3072d30e | 1036 | /* The set of blocks that have been seen on this iteration. */ |
1037 | bitmap processed = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1038 | /* The set of blocks that need to have the out vectors reset because | |
1039 | the in of one of their successors has changed. */ | |
1040 | bitmap redo_out = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1041 | bitmap all_blocks = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1042 | bool global_changed = true; | |
bf1f8fbc | 1043 | |
1044 | /* These regs are considered always live so if they end up dying | |
1045 | because of some def, we need to bring the back again. Calling | |
1046 | df_simulate_fixup_sets has the disadvantage of calling | |
1047 | bb_has_eh_pred once per insn, so we cache the information | |
1048 | here. */ | |
4b5a4301 | 1049 | bitmap au = &df->regular_block_artificial_uses; |
1050 | bitmap au_eh = &df->eh_block_artificial_uses; | |
ebc94641 | 1051 | int i; |
dcd028e1 | 1052 | struct dead_debug_global global_debug; |
3072d30e | 1053 | |
1054 | prescan_insns_for_dce (true); | |
1055 | ||
1056 | for (i = 0; i < n_blocks; i++) | |
1057 | bitmap_set_bit (all_blocks, postorder[i]); | |
1058 | ||
dcd028e1 | 1059 | dead_debug_global_init (&global_debug, NULL); |
1060 | ||
3072d30e | 1061 | while (global_changed) |
1062 | { | |
1063 | global_changed = false; | |
ebc94641 | 1064 | |
3072d30e | 1065 | for (i = 0; i < n_blocks; i++) |
1066 | { | |
1067 | int index = postorder[i]; | |
1068 | basic_block bb = BASIC_BLOCK (index); | |
1069 | bool local_changed; | |
1070 | ||
1071 | if (index < NUM_FIXED_BLOCKS) | |
1072 | { | |
1073 | bitmap_set_bit (processed, index); | |
1074 | continue; | |
1075 | } | |
1076 | ||
0e8e9be3 | 1077 | if (word_level) |
48e1416a | 1078 | local_changed |
dcd028e1 | 1079 | = word_dce_process_block (bb, bitmap_bit_p (redo_out, index), |
1080 | &global_debug); | |
bf1f8fbc | 1081 | else |
48e1416a | 1082 | local_changed |
bf1f8fbc | 1083 | = dce_process_block (bb, bitmap_bit_p (redo_out, index), |
dcd028e1 | 1084 | bb_has_eh_pred (bb) ? au_eh : au, |
1085 | &global_debug); | |
3072d30e | 1086 | bitmap_set_bit (processed, index); |
48e1416a | 1087 | |
3072d30e | 1088 | if (local_changed) |
1089 | { | |
1090 | edge e; | |
1091 | edge_iterator ei; | |
1092 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1093 | if (bitmap_bit_p (processed, e->src->index)) | |
1094 | /* Be tricky about when we need to iterate the | |
1095 | analysis. We only have redo the analysis if the | |
1096 | bitmaps change at the top of a block that is the | |
1097 | entry to a loop. */ | |
1098 | global_changed = true; | |
1099 | else | |
1100 | bitmap_set_bit (redo_out, e->src->index); | |
1101 | } | |
1102 | } | |
48e1416a | 1103 | |
3072d30e | 1104 | if (global_changed) |
1105 | { | |
1106 | /* Turn off the RUN_DCE flag to prevent recursive calls to | |
1107 | dce. */ | |
1108 | int old_flag = df_clear_flags (DF_LR_RUN_DCE); | |
1109 | ||
1110 | /* So something was deleted that requires a redo. Do it on | |
1111 | the cheap. */ | |
1112 | delete_unmarked_insns (); | |
53c5d9d4 | 1113 | bitmap_clear (marked); |
3072d30e | 1114 | bitmap_clear (processed); |
1115 | bitmap_clear (redo_out); | |
48e1416a | 1116 | |
3072d30e | 1117 | /* We do not need to rescan any instructions. We only need |
1118 | to redo the dataflow equations for the blocks that had a | |
1119 | change at the top of the block. Then we need to redo the | |
48e1416a | 1120 | iteration. */ |
0e8e9be3 | 1121 | if (word_level) |
1122 | df_analyze_problem (df_word_lr, all_blocks, postorder, n_blocks); | |
bf1f8fbc | 1123 | else |
1124 | df_analyze_problem (df_lr, all_blocks, postorder, n_blocks); | |
3072d30e | 1125 | |
1126 | if (old_flag & DF_LR_RUN_DCE) | |
1127 | df_set_flags (DF_LR_RUN_DCE); | |
ebc94641 | 1128 | |
3072d30e | 1129 | prescan_insns_for_dce (true); |
1130 | } | |
3072d30e | 1131 | } |
1132 | ||
dcd028e1 | 1133 | dead_debug_global_finish (&global_debug, NULL); |
1134 | ||
3072d30e | 1135 | delete_unmarked_insns (); |
1136 | ||
1137 | BITMAP_FREE (processed); | |
1138 | BITMAP_FREE (redo_out); | |
1139 | BITMAP_FREE (all_blocks); | |
1140 | } | |
1141 | ||
1142 | ||
bf1f8fbc | 1143 | /* Fast register level DCE. */ |
3072d30e | 1144 | |
1145 | static unsigned int | |
1146 | rest_of_handle_fast_dce (void) | |
1147 | { | |
1148 | init_dce (true); | |
bf1f8fbc | 1149 | fast_dce (false); |
1150 | fini_dce (true); | |
1151 | return 0; | |
1152 | } | |
1153 | ||
1154 | ||
1155 | /* Fast byte level DCE. */ | |
1156 | ||
0e8e9be3 | 1157 | void |
1158 | run_word_dce (void) | |
bf1f8fbc | 1159 | { |
55fed53b | 1160 | int old_flags; |
1161 | ||
1162 | if (!flag_dce) | |
1163 | return; | |
1164 | ||
0e8e9be3 | 1165 | timevar_push (TV_DCE); |
55fed53b | 1166 | old_flags = df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
0e8e9be3 | 1167 | df_word_lr_add_problem (); |
bf1f8fbc | 1168 | init_dce (true); |
1169 | fast_dce (true); | |
3c6c0b50 | 1170 | fini_dce (true); |
55fed53b | 1171 | df_set_flags (old_flags); |
0e8e9be3 | 1172 | timevar_pop (TV_DCE); |
3072d30e | 1173 | } |
1174 | ||
1175 | ||
1176 | /* This is an internal call that is used by the df live register | |
1177 | problem to run fast dce as a side effect of creating the live | |
1178 | information. The stack is organized so that the lr problem is run, | |
1179 | this pass is run, which updates the live info and the df scanning | |
1180 | info, and then returns to allow the rest of the problems to be run. | |
1181 | ||
1182 | This can be called by elsewhere but it will not update the bit | |
3c6c0b50 | 1183 | vectors for any other problems than LR. */ |
3072d30e | 1184 | |
1185 | void | |
1186 | run_fast_df_dce (void) | |
1187 | { | |
1188 | if (flag_dce) | |
1189 | { | |
1190 | /* If dce is able to delete something, it has to happen | |
1191 | immediately. Otherwise there will be problems handling the | |
1192 | eq_notes. */ | |
bc620c5c | 1193 | int old_flags = |
1194 | df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); | |
1195 | ||
3072d30e | 1196 | df_in_progress = true; |
1197 | rest_of_handle_fast_dce (); | |
3c6c0b50 | 1198 | df_in_progress = false; |
1199 | ||
3072d30e | 1200 | df_set_flags (old_flags); |
1201 | } | |
1202 | } | |
1203 | ||
3c6c0b50 | 1204 | |
ebc94641 | 1205 | /* Run a fast DCE pass. */ |
1206 | ||
1207 | void | |
1208 | run_fast_dce (void) | |
3072d30e | 1209 | { |
ebc94641 | 1210 | if (flag_dce) |
1211 | rest_of_handle_fast_dce (); | |
3072d30e | 1212 | } |
1213 | ||
1214 | ||
ebc94641 | 1215 | static bool |
1216 | gate_fast_dce (void) | |
3072d30e | 1217 | { |
4ff06051 | 1218 | return optimize > 0 && flag_dce |
1219 | && dbg_cnt (dce_fast); | |
3072d30e | 1220 | } |
1221 | ||
cbe8bda8 | 1222 | namespace { |
1223 | ||
1224 | const pass_data pass_data_fast_rtl_dce = | |
3072d30e | 1225 | { |
cbe8bda8 | 1226 | RTL_PASS, /* type */ |
1227 | "rtl_dce", /* name */ | |
1228 | OPTGROUP_NONE, /* optinfo_flags */ | |
1229 | true, /* has_gate */ | |
1230 | true, /* has_execute */ | |
1231 | TV_DCE, /* tv_id */ | |
1232 | 0, /* properties_required */ | |
1233 | 0, /* properties_provided */ | |
1234 | 0, /* properties_destroyed */ | |
1235 | 0, /* todo_flags_start */ | |
1236 | ( TODO_df_finish | TODO_verify_rtl_sharing ), /* todo_flags_finish */ | |
3072d30e | 1237 | }; |
cbe8bda8 | 1238 | |
1239 | class pass_fast_rtl_dce : public rtl_opt_pass | |
1240 | { | |
1241 | public: | |
1242 | pass_fast_rtl_dce(gcc::context *ctxt) | |
1243 | : rtl_opt_pass(pass_data_fast_rtl_dce, ctxt) | |
1244 | {} | |
1245 | ||
1246 | /* opt_pass methods: */ | |
1247 | bool gate () { return gate_fast_dce (); } | |
1248 | unsigned int execute () { return rest_of_handle_fast_dce (); } | |
1249 | ||
1250 | }; // class pass_fast_rtl_dce | |
1251 | ||
1252 | } // anon namespace | |
1253 | ||
1254 | rtl_opt_pass * | |
1255 | make_pass_fast_rtl_dce (gcc::context *ctxt) | |
1256 | { | |
1257 | return new pass_fast_rtl_dce (ctxt); | |
1258 | } |