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Commit | Line | Data |
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6fb5fa3c | 1 | /* RTL dead code elimination. |
2e0642cd | 2 | Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011 |
d652f226 | 3 | Free Software Foundation, Inc. |
6fb5fa3c DB |
4 | |
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9dcd6f09 | 9 | Software Foundation; either version 3, or (at your option) any later |
6fb5fa3c DB |
10 | version. |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
9dcd6f09 NC |
18 | along with GCC; see the file COPYING3. If not see |
19 | <http://www.gnu.org/licenses/>. */ | |
6fb5fa3c DB |
20 | |
21 | #include "config.h" | |
22 | #include "system.h" | |
23 | #include "coretypes.h" | |
24 | #include "hashtab.h" | |
25 | #include "tm.h" | |
26 | #include "rtl.h" | |
27 | #include "tree.h" | |
28 | #include "regs.h" | |
29 | #include "hard-reg-set.h" | |
30 | #include "flags.h" | |
35debead | 31 | #include "except.h" |
6fb5fa3c DB |
32 | #include "df.h" |
33 | #include "cselib.h" | |
34 | #include "dce.h" | |
08df6c0d | 35 | #include "valtrack.h" |
6fb5fa3c DB |
36 | #include "tree-pass.h" |
37 | #include "dbgcnt.h" | |
0196c95e | 38 | #include "tm_p.h" |
5936d944 | 39 | #include "emit-rtl.h" /* FIXME: Can go away once crtl is moved to rtl.h. */ |
6fb5fa3c | 40 | |
6fb5fa3c DB |
41 | |
42 | /* ------------------------------------------------------------------------- | |
43 | Core mark/delete routines | |
44 | ------------------------------------------------------------------------- */ | |
45 | ||
2e6be65e EB |
46 | /* True if we are invoked while the df engine is running; in this case, |
47 | we don't want to reenter it. */ | |
6fb5fa3c DB |
48 | static bool df_in_progress = false; |
49 | ||
2da02156 EB |
50 | /* True if we are allowed to alter the CFG in this pass. */ |
51 | static bool can_alter_cfg = false; | |
52 | ||
6fb5fa3c DB |
53 | /* Instructions that have been marked but whose dependencies have not |
54 | yet been processed. */ | |
55 | static VEC(rtx,heap) *worklist; | |
56 | ||
2e6be65e EB |
57 | /* Bitmap of instructions marked as needed indexed by INSN_UID. */ |
58 | static sbitmap marked; | |
59 | ||
60 | /* Bitmap obstacks used for block processing by the fast algorithm. */ | |
6fb5fa3c DB |
61 | static bitmap_obstack dce_blocks_bitmap_obstack; |
62 | static bitmap_obstack dce_tmp_bitmap_obstack; | |
63 | ||
0196c95e | 64 | static bool find_call_stack_args (rtx, bool, bool, bitmap); |
6fb5fa3c | 65 | |
d4d7f1d1 RS |
66 | /* A subroutine for which BODY is part of the instruction being tested; |
67 | either the top-level pattern, or an element of a PARALLEL. The | |
68 | instruction is known not to be a bare USE or CLOBBER. */ | |
6fb5fa3c DB |
69 | |
70 | static bool | |
d4d7f1d1 | 71 | deletable_insn_p_1 (rtx body) |
6fb5fa3c | 72 | { |
6cad9859 | 73 | switch (GET_CODE (body)) |
6fb5fa3c | 74 | { |
6fb5fa3c DB |
75 | case PREFETCH: |
76 | case TRAP_IF: | |
77 | /* The UNSPEC case was added here because the ia-64 claims that | |
78 | USEs do not work after reload and generates UNSPECS rather | |
79 | than USEs. Since dce is run after reload we need to avoid | |
80 | deleting these even if they are dead. If it turns out that | |
81 | USEs really do work after reload, the ia-64 should be | |
82 | changed, and the UNSPEC case can be removed. */ | |
83 | case UNSPEC: | |
84 | return false; | |
85 | ||
d4d7f1d1 | 86 | default: |
1d65f45c | 87 | return !volatile_refs_p (body); |
d4d7f1d1 RS |
88 | } |
89 | } | |
90 | ||
2e6be65e | 91 | |
d4d7f1d1 RS |
92 | /* Return true if INSN is a normal instruction that can be deleted by |
93 | the DCE pass. */ | |
94 | ||
95 | static bool | |
0196c95e | 96 | deletable_insn_p (rtx insn, bool fast, bitmap arg_stores) |
d4d7f1d1 RS |
97 | { |
98 | rtx body, x; | |
99 | int i; | |
100 | ||
5ba5ab9b KZ |
101 | if (CALL_P (insn) |
102 | /* We cannot delete calls inside of the recursive dce because | |
103 | this may cause basic blocks to be deleted and this messes up | |
104 | the rest of the stack of optimization passes. */ | |
105 | && (!df_in_progress) | |
106 | /* We cannot delete pure or const sibling calls because it is | |
107 | hard to see the result. */ | |
becfd6e5 | 108 | && (!SIBLING_CALL_P (insn)) |
5ba5ab9b KZ |
109 | /* We can delete dead const or pure calls as long as they do not |
110 | infinite loop. */ | |
becfd6e5 KZ |
111 | && (RTL_CONST_OR_PURE_CALL_P (insn) |
112 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
0196c95e | 113 | return find_call_stack_args (insn, false, fast, arg_stores); |
becfd6e5 | 114 | |
642d55de EB |
115 | /* Don't delete jumps, notes and the like. */ |
116 | if (!NONJUMP_INSN_P (insn)) | |
117 | return false; | |
118 | ||
2da02156 EB |
119 | /* Don't delete insns that may throw if we cannot do so. */ |
120 | if (!(cfun->can_delete_dead_exceptions && can_alter_cfg) | |
121 | && !insn_nothrow_p (insn)) | |
642d55de EB |
122 | return false; |
123 | ||
d4d7f1d1 RS |
124 | body = PATTERN (insn); |
125 | switch (GET_CODE (body)) | |
126 | { | |
127 | case USE: | |
b5b8b0ac | 128 | case VAR_LOCATION: |
d4d7f1d1 RS |
129 | return false; |
130 | ||
6fb5fa3c DB |
131 | case CLOBBER: |
132 | if (fast) | |
133 | { | |
134 | /* A CLOBBER of a dead pseudo register serves no purpose. | |
135 | That is not necessarily true for hard registers until | |
136 | after reload. */ | |
6cad9859 | 137 | x = XEXP (body, 0); |
6fb5fa3c DB |
138 | return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed); |
139 | } | |
d4d7f1d1 | 140 | else |
6fb5fa3c DB |
141 | /* Because of the way that use-def chains are built, it is not |
142 | possible to tell if the clobber is dead because it can | |
143 | never be the target of a use-def chain. */ | |
144 | return false; | |
145 | ||
6cad9859 | 146 | case PARALLEL: |
d4d7f1d1 RS |
147 | for (i = XVECLEN (body, 0) - 1; i >= 0; i--) |
148 | if (!deletable_insn_p_1 (XVECEXP (body, 0, i))) | |
149 | return false; | |
150 | return true; | |
6cad9859 | 151 | |
6fb5fa3c | 152 | default: |
d4d7f1d1 | 153 | return deletable_insn_p_1 (body); |
6fb5fa3c DB |
154 | } |
155 | } | |
156 | ||
157 | ||
2e6be65e | 158 | /* Return true if INSN has been marked as needed. */ |
6fb5fa3c DB |
159 | |
160 | static inline int | |
161 | marked_insn_p (rtx insn) | |
162 | { | |
50e94c7e SB |
163 | /* Artificial defs are always needed and they do not have an insn. |
164 | We should never see them here. */ | |
165 | gcc_assert (insn); | |
166 | return TEST_BIT (marked, INSN_UID (insn)); | |
6fb5fa3c DB |
167 | } |
168 | ||
169 | ||
170 | /* If INSN has not yet been marked as needed, mark it now, and add it to | |
171 | the worklist. */ | |
172 | ||
173 | static void | |
174 | mark_insn (rtx insn, bool fast) | |
175 | { | |
176 | if (!marked_insn_p (insn)) | |
177 | { | |
178 | if (!fast) | |
179 | VEC_safe_push (rtx, heap, worklist, insn); | |
180 | SET_BIT (marked, INSN_UID (insn)); | |
181 | if (dump_file) | |
182 | fprintf (dump_file, " Adding insn %d to worklist\n", INSN_UID (insn)); | |
0196c95e JJ |
183 | if (CALL_P (insn) |
184 | && !df_in_progress | |
185 | && !SIBLING_CALL_P (insn) | |
186 | && (RTL_CONST_OR_PURE_CALL_P (insn) | |
187 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
188 | find_call_stack_args (insn, true, fast, NULL); | |
6fb5fa3c DB |
189 | } |
190 | } | |
191 | ||
192 | ||
193 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
194 | instruction containing DEST. */ | |
195 | ||
196 | static void | |
7bc980e1 | 197 | mark_nonreg_stores_1 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
198 | { |
199 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
200 | mark_insn ((rtx) data, true); | |
201 | } | |
202 | ||
203 | ||
204 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
205 | instruction containing DEST. */ | |
206 | ||
207 | static void | |
7bc980e1 | 208 | mark_nonreg_stores_2 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
209 | { |
210 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
211 | mark_insn ((rtx) data, false); | |
212 | } | |
213 | ||
214 | ||
215 | /* Mark INSN if BODY stores to a non-register destination. */ | |
216 | ||
217 | static void | |
218 | mark_nonreg_stores (rtx body, rtx insn, bool fast) | |
219 | { | |
220 | if (fast) | |
221 | note_stores (body, mark_nonreg_stores_1, insn); | |
222 | else | |
223 | note_stores (body, mark_nonreg_stores_2, insn); | |
224 | } | |
225 | ||
226 | ||
2e0642cd JJ |
227 | /* Return true if store to MEM, starting OFF bytes from stack pointer, |
228 | is a call argument store, and clear corresponding bits from SP_BYTES | |
229 | bitmap if it is. */ | |
230 | ||
231 | static bool | |
232 | check_argument_store (rtx mem, HOST_WIDE_INT off, HOST_WIDE_INT min_sp_off, | |
233 | HOST_WIDE_INT max_sp_off, bitmap sp_bytes) | |
234 | { | |
235 | HOST_WIDE_INT byte; | |
236 | for (byte = off; byte < off + GET_MODE_SIZE (GET_MODE (mem)); byte++) | |
237 | { | |
238 | if (byte < min_sp_off | |
239 | || byte >= max_sp_off | |
240 | || !bitmap_clear_bit (sp_bytes, byte - min_sp_off)) | |
241 | return false; | |
242 | } | |
243 | return true; | |
244 | } | |
245 | ||
246 | ||
0196c95e JJ |
247 | /* Try to find all stack stores of CALL_INSN arguments if |
248 | ACCUMULATE_OUTGOING_ARGS. If all stack stores have been found | |
249 | and it is therefore safe to eliminate the call, return true, | |
250 | otherwise return false. This function should be first called | |
251 | with DO_MARK false, and only when the CALL_INSN is actually | |
252 | going to be marked called again with DO_MARK true. */ | |
253 | ||
254 | static bool | |
255 | find_call_stack_args (rtx call_insn, bool do_mark, bool fast, | |
256 | bitmap arg_stores) | |
257 | { | |
258 | rtx p, insn, prev_insn; | |
259 | bool ret; | |
260 | HOST_WIDE_INT min_sp_off, max_sp_off; | |
261 | bitmap sp_bytes; | |
262 | ||
263 | gcc_assert (CALL_P (call_insn)); | |
264 | if (!ACCUMULATE_OUTGOING_ARGS) | |
265 | return true; | |
266 | ||
267 | if (!do_mark) | |
268 | { | |
269 | gcc_assert (arg_stores); | |
270 | bitmap_clear (arg_stores); | |
271 | } | |
272 | ||
273 | min_sp_off = INTTYPE_MAXIMUM (HOST_WIDE_INT); | |
274 | max_sp_off = 0; | |
275 | ||
276 | /* First determine the minimum and maximum offset from sp for | |
277 | stored arguments. */ | |
278 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
279 | if (GET_CODE (XEXP (p, 0)) == USE | |
280 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
281 | { | |
f5541398 RS |
282 | rtx mem = XEXP (XEXP (p, 0), 0), addr; |
283 | HOST_WIDE_INT off = 0, size; | |
284 | if (!MEM_SIZE_KNOWN_P (mem)) | |
0196c95e | 285 | return false; |
f5541398 | 286 | size = MEM_SIZE (mem); |
0196c95e JJ |
287 | addr = XEXP (mem, 0); |
288 | if (GET_CODE (addr) == PLUS | |
289 | && REG_P (XEXP (addr, 0)) | |
290 | && CONST_INT_P (XEXP (addr, 1))) | |
291 | { | |
292 | off = INTVAL (XEXP (addr, 1)); | |
293 | addr = XEXP (addr, 0); | |
294 | } | |
295 | if (addr != stack_pointer_rtx) | |
296 | { | |
297 | if (!REG_P (addr)) | |
298 | return false; | |
299 | /* If not fast, use chains to see if addr wasn't set to | |
300 | sp + offset. */ | |
301 | if (!fast) | |
302 | { | |
303 | df_ref *use_rec; | |
304 | struct df_link *defs; | |
305 | rtx set; | |
306 | ||
307 | for (use_rec = DF_INSN_USES (call_insn); *use_rec; use_rec++) | |
308 | if (rtx_equal_p (addr, DF_REF_REG (*use_rec))) | |
309 | break; | |
310 | ||
311 | if (*use_rec == NULL) | |
312 | return false; | |
313 | ||
314 | for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next) | |
315 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) | |
316 | break; | |
317 | ||
318 | if (defs == NULL) | |
319 | return false; | |
320 | ||
321 | set = single_set (DF_REF_INSN (defs->ref)); | |
322 | if (!set) | |
323 | return false; | |
324 | ||
325 | if (GET_CODE (SET_SRC (set)) != PLUS | |
326 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
327 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
328 | return false; | |
329 | ||
330 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
331 | } | |
332 | else | |
333 | return false; | |
334 | } | |
335 | min_sp_off = MIN (min_sp_off, off); | |
f5541398 | 336 | max_sp_off = MAX (max_sp_off, off + size); |
0196c95e JJ |
337 | } |
338 | ||
339 | if (min_sp_off >= max_sp_off) | |
340 | return true; | |
341 | sp_bytes = BITMAP_ALLOC (NULL); | |
342 | ||
343 | /* Set bits in SP_BYTES bitmap for bytes relative to sp + min_sp_off | |
344 | which contain arguments. Checking has been done in the previous | |
345 | loop. */ | |
346 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
347 | if (GET_CODE (XEXP (p, 0)) == USE | |
348 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
349 | { | |
350 | rtx mem = XEXP (XEXP (p, 0), 0), addr; | |
351 | HOST_WIDE_INT off = 0, byte; | |
352 | addr = XEXP (mem, 0); | |
353 | if (GET_CODE (addr) == PLUS | |
354 | && REG_P (XEXP (addr, 0)) | |
355 | && CONST_INT_P (XEXP (addr, 1))) | |
356 | { | |
357 | off = INTVAL (XEXP (addr, 1)); | |
358 | addr = XEXP (addr, 0); | |
359 | } | |
360 | if (addr != stack_pointer_rtx) | |
361 | { | |
362 | df_ref *use_rec; | |
363 | struct df_link *defs; | |
364 | rtx set; | |
365 | ||
366 | for (use_rec = DF_INSN_USES (call_insn); *use_rec; use_rec++) | |
367 | if (rtx_equal_p (addr, DF_REF_REG (*use_rec))) | |
368 | break; | |
369 | ||
370 | for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next) | |
371 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) | |
372 | break; | |
373 | ||
374 | set = single_set (DF_REF_INSN (defs->ref)); | |
375 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
376 | } | |
f5541398 | 377 | for (byte = off; byte < off + MEM_SIZE (mem); byte++) |
0196c95e | 378 | { |
821bb7f8 RG |
379 | if (!bitmap_set_bit (sp_bytes, byte - min_sp_off)) |
380 | gcc_unreachable (); | |
0196c95e JJ |
381 | } |
382 | } | |
383 | ||
384 | /* Walk backwards, looking for argument stores. The search stops | |
750900db | 385 | when seeing another call, sp adjustment or memory store other than |
0196c95e JJ |
386 | argument store. */ |
387 | ret = false; | |
388 | for (insn = PREV_INSN (call_insn); insn; insn = prev_insn) | |
389 | { | |
390 | rtx set, mem, addr; | |
2e0642cd | 391 | HOST_WIDE_INT off; |
0196c95e JJ |
392 | |
393 | if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn))) | |
394 | prev_insn = NULL_RTX; | |
395 | else | |
396 | prev_insn = PREV_INSN (insn); | |
397 | ||
398 | if (CALL_P (insn)) | |
399 | break; | |
400 | ||
2e0642cd | 401 | if (!NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
402 | continue; |
403 | ||
404 | set = single_set (insn); | |
405 | if (!set || SET_DEST (set) == stack_pointer_rtx) | |
406 | break; | |
407 | ||
408 | if (!MEM_P (SET_DEST (set))) | |
409 | continue; | |
410 | ||
411 | mem = SET_DEST (set); | |
412 | addr = XEXP (mem, 0); | |
413 | off = 0; | |
414 | if (GET_CODE (addr) == PLUS | |
415 | && REG_P (XEXP (addr, 0)) | |
416 | && CONST_INT_P (XEXP (addr, 1))) | |
417 | { | |
418 | off = INTVAL (XEXP (addr, 1)); | |
419 | addr = XEXP (addr, 0); | |
420 | } | |
421 | if (addr != stack_pointer_rtx) | |
422 | { | |
423 | if (!REG_P (addr)) | |
424 | break; | |
425 | if (!fast) | |
426 | { | |
427 | df_ref *use_rec; | |
428 | struct df_link *defs; | |
429 | rtx set; | |
430 | ||
431 | for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++) | |
432 | if (rtx_equal_p (addr, DF_REF_REG (*use_rec))) | |
433 | break; | |
434 | ||
435 | if (*use_rec == NULL) | |
436 | break; | |
437 | ||
438 | for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next) | |
439 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) | |
440 | break; | |
441 | ||
442 | if (defs == NULL) | |
443 | break; | |
444 | ||
445 | set = single_set (DF_REF_INSN (defs->ref)); | |
446 | if (!set) | |
447 | break; | |
448 | ||
449 | if (GET_CODE (SET_SRC (set)) != PLUS | |
450 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
451 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
452 | break; | |
453 | ||
454 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
455 | } | |
456 | else | |
457 | break; | |
458 | } | |
459 | ||
2e0642cd JJ |
460 | if (GET_MODE_SIZE (GET_MODE (mem)) == 0 |
461 | || !check_argument_store (mem, off, min_sp_off, | |
462 | max_sp_off, sp_bytes)) | |
0196c95e JJ |
463 | break; |
464 | ||
0196c95e JJ |
465 | if (!deletable_insn_p (insn, fast, NULL)) |
466 | break; | |
467 | ||
468 | if (do_mark) | |
469 | mark_insn (insn, fast); | |
470 | else | |
471 | bitmap_set_bit (arg_stores, INSN_UID (insn)); | |
472 | ||
473 | if (bitmap_empty_p (sp_bytes)) | |
474 | { | |
475 | ret = true; | |
476 | break; | |
477 | } | |
478 | } | |
479 | ||
480 | BITMAP_FREE (sp_bytes); | |
481 | if (!ret && arg_stores) | |
482 | bitmap_clear (arg_stores); | |
483 | ||
484 | return ret; | |
485 | } | |
486 | ||
487 | ||
885c9b5d EB |
488 | /* Remove all REG_EQUAL and REG_EQUIV notes referring to the registers INSN |
489 | writes to. */ | |
6fb5fa3c DB |
490 | |
491 | static void | |
885c9b5d | 492 | remove_reg_equal_equiv_notes_for_defs (rtx insn) |
6fb5fa3c | 493 | { |
57512f53 | 494 | df_ref *def_rec; |
885c9b5d | 495 | |
6fb5fa3c | 496 | for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++) |
885c9b5d | 497 | remove_reg_equal_equiv_notes_for_regno (DF_REF_REGNO (*def_rec)); |
6fb5fa3c DB |
498 | } |
499 | ||
a7a110bb AO |
500 | /* Scan all BBs for debug insns and reset those that reference values |
501 | defined in unmarked insns. */ | |
502 | ||
503 | static void | |
504 | reset_unmarked_insns_debug_uses (void) | |
505 | { | |
506 | basic_block bb; | |
507 | rtx insn, next; | |
508 | ||
509 | FOR_EACH_BB_REVERSE (bb) | |
510 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) | |
511 | if (DEBUG_INSN_P (insn)) | |
512 | { | |
513 | df_ref *use_rec; | |
514 | ||
515 | for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++) | |
516 | { | |
517 | df_ref use = *use_rec; | |
518 | struct df_link *defs; | |
519 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
520 | { | |
8ced31fe | 521 | rtx ref_insn; |
a7a110bb AO |
522 | if (DF_REF_IS_ARTIFICIAL (defs->ref)) |
523 | continue; | |
8ced31fe JJ |
524 | ref_insn = DF_REF_INSN (defs->ref); |
525 | if (!marked_insn_p (ref_insn)) | |
a7a110bb AO |
526 | break; |
527 | } | |
528 | if (!defs) | |
529 | continue; | |
530 | /* ??? FIXME could we propagate the values assigned to | |
531 | each of the DEFs? */ | |
532 | INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC (); | |
533 | df_insn_rescan_debug_internal (insn); | |
8ced31fe | 534 | break; |
a7a110bb AO |
535 | } |
536 | } | |
537 | } | |
6fb5fa3c | 538 | |
9ed7b221 | 539 | /* Delete every instruction that hasn't been marked. */ |
6fb5fa3c DB |
540 | |
541 | static void | |
542 | delete_unmarked_insns (void) | |
543 | { | |
544 | basic_block bb; | |
545 | rtx insn, next; | |
5ba5ab9b | 546 | bool must_clean = false; |
6fb5fa3c | 547 | |
cd3f1729 KZ |
548 | FOR_EACH_BB_REVERSE (bb) |
549 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) | |
a7a110bb | 550 | if (NONDEBUG_INSN_P (insn)) |
6fb5fa3c | 551 | { |
9ed7b221 | 552 | /* Always delete no-op moves. */ |
6fb5fa3c | 553 | if (noop_move_p (insn)) |
9ed7b221 EB |
554 | ; |
555 | ||
9ed7b221 | 556 | /* Otherwise rely only on the DCE algorithm. */ |
6fb5fa3c DB |
557 | else if (marked_insn_p (insn)) |
558 | continue; | |
559 | ||
cd3f1729 KZ |
560 | /* Beware that reaching a dbg counter limit here can result |
561 | in miscompiled file. This occurs when a group of insns | |
562 | must be deleted together, typically because the kept insn | |
563 | depends on the output from the deleted insn. Deleting | |
564 | this insns in reverse order (both at the bb level and | |
565 | when looking at the blocks) minimizes this, but does not | |
566 | eliminate it, since it is possible for the using insn to | |
567 | be top of a block and the producer to be at the bottom of | |
568 | the block. However, in most cases this will only result | |
569 | in an uninitialized use of an insn that is dead anyway. | |
570 | ||
571 | However, there is one rare case that will cause a | |
572 | miscompile: deletion of non-looping pure and constant | |
573 | calls on a machine where ACCUMULATE_OUTGOING_ARGS is true. | |
574 | In this case it is possible to remove the call, but leave | |
575 | the argument pushes to the stack. Because of the changes | |
576 | to the stack pointer, this will almost always lead to a | |
577 | miscompile. */ | |
6fb5fa3c DB |
578 | if (!dbg_cnt (dce)) |
579 | continue; | |
580 | ||
581 | if (dump_file) | |
582 | fprintf (dump_file, "DCE: Deleting insn %d\n", INSN_UID (insn)); | |
583 | ||
885c9b5d | 584 | /* Before we delete the insn we have to remove the REG_EQUAL notes |
9ed7b221 | 585 | for the destination regs in order to avoid dangling notes. */ |
885c9b5d | 586 | remove_reg_equal_equiv_notes_for_defs (insn); |
6fb5fa3c | 587 | |
5ba5ab9b KZ |
588 | /* If a pure or const call is deleted, this may make the cfg |
589 | have unreachable blocks. We rememeber this and call | |
590 | delete_unreachable_blocks at the end. */ | |
591 | if (CALL_P (insn)) | |
592 | must_clean = true; | |
593 | ||
9ed7b221 | 594 | /* Now delete the insn. */ |
6fb5fa3c | 595 | delete_insn_and_edges (insn); |
6fb5fa3c | 596 | } |
5ba5ab9b KZ |
597 | |
598 | /* Deleted a pure or const call. */ | |
599 | if (must_clean) | |
600 | delete_unreachable_blocks (); | |
6fb5fa3c DB |
601 | } |
602 | ||
603 | ||
6fb5fa3c DB |
604 | /* Go through the instructions and mark those whose necessity is not |
605 | dependent on inter-instruction information. Make sure all other | |
606 | instructions are not marked. */ | |
607 | ||
608 | static void | |
609 | prescan_insns_for_dce (bool fast) | |
610 | { | |
611 | basic_block bb; | |
0196c95e JJ |
612 | rtx insn, prev; |
613 | bitmap arg_stores = NULL; | |
614 | ||
6fb5fa3c DB |
615 | if (dump_file) |
616 | fprintf (dump_file, "Finding needed instructions:\n"); | |
0196c95e JJ |
617 | |
618 | if (!df_in_progress && ACCUMULATE_OUTGOING_ARGS) | |
619 | arg_stores = BITMAP_ALLOC (NULL); | |
620 | ||
6fb5fa3c | 621 | FOR_EACH_BB (bb) |
0196c95e JJ |
622 | { |
623 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev) | |
a7a110bb | 624 | if (NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
625 | { |
626 | /* Don't mark argument stores now. They will be marked | |
627 | if needed when the associated CALL is marked. */ | |
628 | if (arg_stores && bitmap_bit_p (arg_stores, INSN_UID (insn))) | |
629 | continue; | |
630 | if (deletable_insn_p (insn, fast, arg_stores)) | |
631 | mark_nonreg_stores (PATTERN (insn), insn, fast); | |
632 | else | |
633 | mark_insn (insn, fast); | |
634 | } | |
635 | /* find_call_stack_args only looks at argument stores in the | |
636 | same bb. */ | |
637 | if (arg_stores) | |
638 | bitmap_clear (arg_stores); | |
639 | } | |
640 | ||
641 | if (arg_stores) | |
642 | BITMAP_FREE (arg_stores); | |
6fb5fa3c DB |
643 | |
644 | if (dump_file) | |
645 | fprintf (dump_file, "Finished finding needed instructions:\n"); | |
646 | } | |
647 | ||
648 | ||
649 | /* UD-based DSE routines. */ | |
650 | ||
6ed3da00 | 651 | /* Mark instructions that define artificially-used registers, such as |
6fb5fa3c DB |
652 | the frame pointer and the stack pointer. */ |
653 | ||
654 | static void | |
655 | mark_artificial_uses (void) | |
656 | { | |
657 | basic_block bb; | |
658 | struct df_link *defs; | |
57512f53 | 659 | df_ref *use_rec; |
6fb5fa3c DB |
660 | |
661 | FOR_ALL_BB (bb) | |
662 | { | |
b8698a0f | 663 | for (use_rec = df_get_artificial_uses (bb->index); |
6fb5fa3c DB |
664 | *use_rec; use_rec++) |
665 | for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next) | |
50e94c7e SB |
666 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
667 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
668 | } |
669 | } | |
670 | ||
2e6be65e | 671 | |
6fb5fa3c DB |
672 | /* Mark every instruction that defines a register value that INSN uses. */ |
673 | ||
674 | static void | |
675 | mark_reg_dependencies (rtx insn) | |
676 | { | |
677 | struct df_link *defs; | |
57512f53 | 678 | df_ref *use_rec; |
6fb5fa3c | 679 | |
b5b8b0ac AO |
680 | if (DEBUG_INSN_P (insn)) |
681 | return; | |
682 | ||
6fb5fa3c DB |
683 | for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++) |
684 | { | |
57512f53 | 685 | df_ref use = *use_rec; |
6fb5fa3c DB |
686 | if (dump_file) |
687 | { | |
688 | fprintf (dump_file, "Processing use of "); | |
689 | print_simple_rtl (dump_file, DF_REF_REG (use)); | |
690 | fprintf (dump_file, " in insn %d:\n", INSN_UID (insn)); | |
691 | } | |
692 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
50e94c7e SB |
693 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
694 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
695 | } |
696 | } | |
697 | ||
698 | ||
2e6be65e EB |
699 | /* Initialize global variables for a new DCE pass. */ |
700 | ||
6fb5fa3c | 701 | static void |
2e6be65e EB |
702 | init_dce (bool fast) |
703 | { | |
704 | if (!df_in_progress) | |
705 | { | |
706 | if (!fast) | |
7b19209f SB |
707 | { |
708 | df_set_flags (DF_RD_PRUNE_DEAD_DEFS); | |
709 | df_chain_add_problem (DF_UD_CHAIN); | |
710 | } | |
2e6be65e EB |
711 | df_analyze (); |
712 | } | |
713 | ||
714 | if (dump_file) | |
715 | df_dump (dump_file); | |
716 | ||
717 | if (fast) | |
718 | { | |
719 | bitmap_obstack_initialize (&dce_blocks_bitmap_obstack); | |
720 | bitmap_obstack_initialize (&dce_tmp_bitmap_obstack); | |
2da02156 | 721 | can_alter_cfg = false; |
2e6be65e | 722 | } |
2da02156 EB |
723 | else |
724 | can_alter_cfg = true; | |
2e6be65e EB |
725 | |
726 | marked = sbitmap_alloc (get_max_uid () + 1); | |
727 | sbitmap_zero (marked); | |
728 | } | |
729 | ||
730 | ||
731 | /* Free the data allocated by init_dce. */ | |
732 | ||
733 | static void | |
734 | fini_dce (bool fast) | |
6fb5fa3c DB |
735 | { |
736 | sbitmap_free (marked); | |
2e6be65e EB |
737 | |
738 | if (fast) | |
739 | { | |
740 | bitmap_obstack_release (&dce_blocks_bitmap_obstack); | |
741 | bitmap_obstack_release (&dce_tmp_bitmap_obstack); | |
742 | } | |
6fb5fa3c DB |
743 | } |
744 | ||
745 | ||
746 | /* UD-chain based DCE. */ | |
747 | ||
748 | static unsigned int | |
749 | rest_of_handle_ud_dce (void) | |
750 | { | |
751 | rtx insn; | |
752 | ||
6fb5fa3c DB |
753 | init_dce (false); |
754 | ||
755 | prescan_insns_for_dce (false); | |
756 | mark_artificial_uses (); | |
757 | while (VEC_length (rtx, worklist) > 0) | |
758 | { | |
759 | insn = VEC_pop (rtx, worklist); | |
760 | mark_reg_dependencies (insn); | |
761 | } | |
cf975747 | 762 | VEC_free (rtx, heap, worklist); |
2e6be65e | 763 | |
a7a110bb AO |
764 | if (MAY_HAVE_DEBUG_INSNS) |
765 | reset_unmarked_insns_debug_uses (); | |
766 | ||
6fb5fa3c DB |
767 | /* Before any insns are deleted, we must remove the chains since |
768 | they are not bidirectional. */ | |
769 | df_remove_problem (df_chain); | |
770 | delete_unmarked_insns (); | |
771 | ||
2e6be65e | 772 | fini_dce (false); |
6fb5fa3c DB |
773 | return 0; |
774 | } | |
775 | ||
776 | ||
777 | static bool | |
778 | gate_ud_dce (void) | |
779 | { | |
7d817ebc DE |
780 | return optimize > 1 && flag_dce |
781 | && dbg_cnt (dce_ud); | |
6fb5fa3c DB |
782 | } |
783 | ||
8ddbbcae | 784 | struct rtl_opt_pass pass_ud_rtl_dce = |
6fb5fa3c | 785 | { |
8ddbbcae JH |
786 | { |
787 | RTL_PASS, | |
5f57dccb | 788 | "ud_dce", /* name */ |
e0a42b0f ZC |
789 | gate_ud_dce, /* gate */ |
790 | rest_of_handle_ud_dce, /* execute */ | |
6fb5fa3c DB |
791 | NULL, /* sub */ |
792 | NULL, /* next */ | |
793 | 0, /* static_pass_number */ | |
794 | TV_DCE, /* tv_id */ | |
795 | 0, /* properties_required */ | |
796 | 0, /* properties_provided */ | |
797 | 0, /* properties_destroyed */ | |
798 | 0, /* todo_flags_start */ | |
a36b8a1e | 799 | TODO_df_finish | TODO_verify_rtl_sharing | |
8ddbbcae JH |
800 | TODO_ggc_collect /* todo_flags_finish */ |
801 | } | |
6fb5fa3c DB |
802 | }; |
803 | ||
2e6be65e | 804 | |
6fb5fa3c DB |
805 | /* ------------------------------------------------------------------------- |
806 | Fast DCE functions | |
807 | ------------------------------------------------------------------------- */ | |
808 | ||
cc806ac1 RS |
809 | /* Process basic block BB. Return true if the live_in set has |
810 | changed. REDO_OUT is true if the info at the bottom of the block | |
811 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
812 | artificial uses. Track global substitution of uses of dead pseudos |
813 | in debug insns using GLOBAL_DEBUG. */ | |
6fb5fa3c DB |
814 | |
815 | static bool | |
e9f950ba AO |
816 | word_dce_process_block (basic_block bb, bool redo_out, |
817 | struct dead_debug_global *global_debug) | |
6fb5fa3c DB |
818 | { |
819 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
820 | rtx insn; | |
821 | bool block_changed; | |
e9f950ba | 822 | struct dead_debug_local debug; |
6fb5fa3c DB |
823 | |
824 | if (redo_out) | |
825 | { | |
826 | /* Need to redo the live_out set of this block if when one of | |
827 | the succs of this block has had a change in it live in | |
828 | set. */ | |
829 | edge e; | |
830 | edge_iterator ei; | |
8d074192 BS |
831 | df_confluence_function_n con_fun_n = df_word_lr->problem->con_fun_n; |
832 | bitmap_clear (DF_WORD_LR_OUT (bb)); | |
6fb5fa3c DB |
833 | FOR_EACH_EDGE (e, ei, bb->succs) |
834 | (*con_fun_n) (e); | |
835 | } | |
836 | ||
837 | if (dump_file) | |
838 | { | |
839 | fprintf (dump_file, "processing block %d live out = ", bb->index); | |
8d074192 | 840 | df_print_word_regset (dump_file, DF_WORD_LR_OUT (bb)); |
6fb5fa3c DB |
841 | } |
842 | ||
8d074192 | 843 | bitmap_copy (local_live, DF_WORD_LR_OUT (bb)); |
e9f950ba | 844 | dead_debug_local_init (&debug, NULL, global_debug); |
cc806ac1 RS |
845 | |
846 | FOR_BB_INSNS_REVERSE (bb, insn) | |
1adbb361 AO |
847 | if (DEBUG_INSN_P (insn)) |
848 | { | |
849 | df_ref *use_rec; | |
850 | for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++) | |
851 | if (DF_REF_REGNO (*use_rec) >= FIRST_PSEUDO_REGISTER | |
852 | && (GET_MODE_SIZE (GET_MODE (DF_REF_REAL_REG (*use_rec))) | |
853 | == 2 * UNITS_PER_WORD) | |
854 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (*use_rec)) | |
855 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (*use_rec) + 1)) | |
0951ac86 | 856 | dead_debug_add (&debug, *use_rec, DF_REF_REGNO (*use_rec)); |
1adbb361 AO |
857 | } |
858 | else if (INSN_P (insn)) | |
cc806ac1 | 859 | { |
8d074192 | 860 | bool any_changed; |
1adbb361 | 861 | |
cc806ac1 RS |
862 | /* No matter if the instruction is needed or not, we remove |
863 | any regno in the defs from the live set. */ | |
8d074192 BS |
864 | any_changed = df_word_lr_simulate_defs (insn, local_live); |
865 | if (any_changed) | |
866 | mark_insn (insn, true); | |
cc806ac1 RS |
867 | |
868 | /* On the other hand, we do not allow the dead uses to set | |
869 | anything in local_live. */ | |
870 | if (marked_insn_p (insn)) | |
8d074192 | 871 | df_word_lr_simulate_uses (insn, local_live); |
6f9e260c | 872 | |
39bc0f01 | 873 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
874 | insns. We may have to emit a debug temp even if the insn |
875 | was marked, in case the debug use was after the point of | |
876 | death. */ | |
877 | if (debug.used && !bitmap_empty_p (debug.used)) | |
1adbb361 AO |
878 | { |
879 | df_ref *def_rec; | |
880 | ||
881 | for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++) | |
882 | dead_debug_insert_temp (&debug, DF_REF_REGNO (*def_rec), insn, | |
883 | DEBUG_TEMP_BEFORE_WITH_VALUE); | |
884 | } | |
885 | ||
cc806ac1 RS |
886 | if (dump_file) |
887 | { | |
b8698a0f | 888 | fprintf (dump_file, "finished processing insn %d live out = ", |
cc806ac1 | 889 | INSN_UID (insn)); |
8d074192 | 890 | df_print_word_regset (dump_file, local_live); |
cc806ac1 RS |
891 | } |
892 | } | |
b8698a0f | 893 | |
8d074192 | 894 | block_changed = !bitmap_equal_p (local_live, DF_WORD_LR_IN (bb)); |
cc806ac1 | 895 | if (block_changed) |
8d074192 BS |
896 | bitmap_copy (DF_WORD_LR_IN (bb), local_live); |
897 | ||
e9f950ba | 898 | dead_debug_local_finish (&debug, NULL); |
cc806ac1 RS |
899 | BITMAP_FREE (local_live); |
900 | return block_changed; | |
901 | } | |
902 | ||
903 | ||
904 | /* Process basic block BB. Return true if the live_in set has | |
905 | changed. REDO_OUT is true if the info at the bottom of the block | |
906 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
907 | artificial uses. Track global substitution of uses of dead pseudos |
908 | in debug insns using GLOBAL_DEBUG. */ | |
cc806ac1 RS |
909 | |
910 | static bool | |
e9f950ba AO |
911 | dce_process_block (basic_block bb, bool redo_out, bitmap au, |
912 | struct dead_debug_global *global_debug) | |
cc806ac1 RS |
913 | { |
914 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
915 | rtx insn; | |
916 | bool block_changed; | |
57512f53 | 917 | df_ref *def_rec; |
e9f950ba | 918 | struct dead_debug_local debug; |
6fb5fa3c | 919 | |
cc806ac1 | 920 | if (redo_out) |
6fb5fa3c | 921 | { |
cc806ac1 RS |
922 | /* Need to redo the live_out set of this block if when one of |
923 | the succs of this block has had a change in it live in | |
924 | set. */ | |
925 | edge e; | |
926 | edge_iterator ei; | |
927 | df_confluence_function_n con_fun_n = df_lr->problem->con_fun_n; | |
928 | bitmap_clear (DF_LR_OUT (bb)); | |
929 | FOR_EACH_EDGE (e, ei, bb->succs) | |
930 | (*con_fun_n) (e); | |
6fb5fa3c DB |
931 | } |
932 | ||
cc806ac1 | 933 | if (dump_file) |
6fb5fa3c | 934 | { |
fafe34f9 | 935 | fprintf (dump_file, "processing block %d lr out = ", bb->index); |
cc806ac1 | 936 | df_print_regset (dump_file, DF_LR_OUT (bb)); |
6fb5fa3c DB |
937 | } |
938 | ||
cc806ac1 RS |
939 | bitmap_copy (local_live, DF_LR_OUT (bb)); |
940 | ||
02b47899 | 941 | df_simulate_initialize_backwards (bb, local_live); |
e9f950ba | 942 | dead_debug_local_init (&debug, NULL, global_debug); |
541d3103 | 943 | |
6fb5fa3c | 944 | FOR_BB_INSNS_REVERSE (bb, insn) |
1adbb361 AO |
945 | if (DEBUG_INSN_P (insn)) |
946 | { | |
947 | df_ref *use_rec; | |
948 | for (use_rec = DF_INSN_USES (insn); *use_rec; use_rec++) | |
949 | if (!bitmap_bit_p (local_live, DF_REF_REGNO (*use_rec)) | |
950 | && !bitmap_bit_p (au, DF_REF_REGNO (*use_rec))) | |
0951ac86 | 951 | dead_debug_add (&debug, *use_rec, DF_REF_REGNO (*use_rec)); |
1adbb361 AO |
952 | } |
953 | else if (INSN_P (insn)) | |
6fb5fa3c | 954 | { |
f251709a | 955 | bool needed = marked_insn_p (insn); |
9ed7b221 EB |
956 | |
957 | /* The insn is needed if there is someone who uses the output. */ | |
f251709a JH |
958 | if (!needed) |
959 | for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++) | |
39bc0f01 AO |
960 | if (bitmap_bit_p (local_live, DF_REF_REGNO (*def_rec)) |
961 | || bitmap_bit_p (au, DF_REF_REGNO (*def_rec))) | |
962 | { | |
963 | needed = true; | |
964 | mark_insn (insn, true); | |
965 | break; | |
966 | } | |
b8698a0f | 967 | |
6fb5fa3c DB |
968 | /* No matter if the instruction is needed or not, we remove |
969 | any regno in the defs from the live set. */ | |
970 | df_simulate_defs (insn, local_live); | |
971 | ||
972 | /* On the other hand, we do not allow the dead uses to set | |
973 | anything in local_live. */ | |
f251709a | 974 | if (needed) |
6fb5fa3c | 975 | df_simulate_uses (insn, local_live); |
6f9e260c | 976 | |
39bc0f01 | 977 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
978 | insns. We may have to emit a debug temp even if the insn |
979 | was marked, in case the debug use was after the point of | |
980 | death. */ | |
981 | if (debug.used && !bitmap_empty_p (debug.used)) | |
39bc0f01 AO |
982 | for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++) |
983 | dead_debug_insert_temp (&debug, DF_REF_REGNO (*def_rec), insn, | |
984 | DEBUG_TEMP_BEFORE_WITH_VALUE); | |
6fb5fa3c | 985 | } |
b8698a0f | 986 | |
e9f950ba | 987 | dead_debug_local_finish (&debug, NULL); |
02b47899 | 988 | df_simulate_finalize_backwards (bb, local_live); |
6fb5fa3c DB |
989 | |
990 | block_changed = !bitmap_equal_p (local_live, DF_LR_IN (bb)); | |
991 | if (block_changed) | |
992 | bitmap_copy (DF_LR_IN (bb), local_live); | |
993 | ||
994 | BITMAP_FREE (local_live); | |
995 | return block_changed; | |
996 | } | |
997 | ||
2e6be65e | 998 | |
8d074192 BS |
999 | /* Perform fast DCE once initialization is done. If WORD_LEVEL is |
1000 | true, use the word level dce, otherwise do it at the pseudo | |
cc806ac1 | 1001 | level. */ |
2e6be65e | 1002 | |
6fb5fa3c | 1003 | static void |
8d074192 | 1004 | fast_dce (bool word_level) |
6fb5fa3c DB |
1005 | { |
1006 | int *postorder = df_get_postorder (DF_BACKWARD); | |
1007 | int n_blocks = df_get_n_blocks (DF_BACKWARD); | |
6fb5fa3c DB |
1008 | /* The set of blocks that have been seen on this iteration. */ |
1009 | bitmap processed = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1010 | /* The set of blocks that need to have the out vectors reset because | |
1011 | the in of one of their successors has changed. */ | |
1012 | bitmap redo_out = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1013 | bitmap all_blocks = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1014 | bool global_changed = true; | |
cc806ac1 RS |
1015 | |
1016 | /* These regs are considered always live so if they end up dying | |
1017 | because of some def, we need to bring the back again. Calling | |
1018 | df_simulate_fixup_sets has the disadvantage of calling | |
1019 | bb_has_eh_pred once per insn, so we cache the information | |
1020 | here. */ | |
a7e3698d JH |
1021 | bitmap au = &df->regular_block_artificial_uses; |
1022 | bitmap au_eh = &df->eh_block_artificial_uses; | |
9ed7b221 | 1023 | int i; |
e9f950ba | 1024 | struct dead_debug_global global_debug; |
6fb5fa3c DB |
1025 | |
1026 | prescan_insns_for_dce (true); | |
1027 | ||
1028 | for (i = 0; i < n_blocks; i++) | |
1029 | bitmap_set_bit (all_blocks, postorder[i]); | |
1030 | ||
e9f950ba AO |
1031 | dead_debug_global_init (&global_debug, NULL); |
1032 | ||
6fb5fa3c DB |
1033 | while (global_changed) |
1034 | { | |
1035 | global_changed = false; | |
9ed7b221 | 1036 | |
6fb5fa3c DB |
1037 | for (i = 0; i < n_blocks; i++) |
1038 | { | |
1039 | int index = postorder[i]; | |
1040 | basic_block bb = BASIC_BLOCK (index); | |
1041 | bool local_changed; | |
1042 | ||
1043 | if (index < NUM_FIXED_BLOCKS) | |
1044 | { | |
1045 | bitmap_set_bit (processed, index); | |
1046 | continue; | |
1047 | } | |
1048 | ||
8d074192 | 1049 | if (word_level) |
b8698a0f | 1050 | local_changed |
e9f950ba AO |
1051 | = word_dce_process_block (bb, bitmap_bit_p (redo_out, index), |
1052 | &global_debug); | |
cc806ac1 | 1053 | else |
b8698a0f | 1054 | local_changed |
cc806ac1 | 1055 | = dce_process_block (bb, bitmap_bit_p (redo_out, index), |
e9f950ba AO |
1056 | bb_has_eh_pred (bb) ? au_eh : au, |
1057 | &global_debug); | |
6fb5fa3c | 1058 | bitmap_set_bit (processed, index); |
b8698a0f | 1059 | |
6fb5fa3c DB |
1060 | if (local_changed) |
1061 | { | |
1062 | edge e; | |
1063 | edge_iterator ei; | |
1064 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1065 | if (bitmap_bit_p (processed, e->src->index)) | |
1066 | /* Be tricky about when we need to iterate the | |
1067 | analysis. We only have redo the analysis if the | |
1068 | bitmaps change at the top of a block that is the | |
1069 | entry to a loop. */ | |
1070 | global_changed = true; | |
1071 | else | |
1072 | bitmap_set_bit (redo_out, e->src->index); | |
1073 | } | |
1074 | } | |
b8698a0f | 1075 | |
6fb5fa3c DB |
1076 | if (global_changed) |
1077 | { | |
1078 | /* Turn off the RUN_DCE flag to prevent recursive calls to | |
1079 | dce. */ | |
1080 | int old_flag = df_clear_flags (DF_LR_RUN_DCE); | |
1081 | ||
1082 | /* So something was deleted that requires a redo. Do it on | |
1083 | the cheap. */ | |
1084 | delete_unmarked_insns (); | |
1085 | sbitmap_zero (marked); | |
1086 | bitmap_clear (processed); | |
1087 | bitmap_clear (redo_out); | |
b8698a0f | 1088 | |
6fb5fa3c DB |
1089 | /* We do not need to rescan any instructions. We only need |
1090 | to redo the dataflow equations for the blocks that had a | |
1091 | change at the top of the block. Then we need to redo the | |
b8698a0f | 1092 | iteration. */ |
8d074192 BS |
1093 | if (word_level) |
1094 | df_analyze_problem (df_word_lr, all_blocks, postorder, n_blocks); | |
cc806ac1 RS |
1095 | else |
1096 | df_analyze_problem (df_lr, all_blocks, postorder, n_blocks); | |
6fb5fa3c DB |
1097 | |
1098 | if (old_flag & DF_LR_RUN_DCE) | |
1099 | df_set_flags (DF_LR_RUN_DCE); | |
9ed7b221 | 1100 | |
6fb5fa3c DB |
1101 | prescan_insns_for_dce (true); |
1102 | } | |
6fb5fa3c DB |
1103 | } |
1104 | ||
e9f950ba AO |
1105 | dead_debug_global_finish (&global_debug, NULL); |
1106 | ||
6fb5fa3c DB |
1107 | delete_unmarked_insns (); |
1108 | ||
1109 | BITMAP_FREE (processed); | |
1110 | BITMAP_FREE (redo_out); | |
1111 | BITMAP_FREE (all_blocks); | |
1112 | } | |
1113 | ||
1114 | ||
cc806ac1 | 1115 | /* Fast register level DCE. */ |
6fb5fa3c DB |
1116 | |
1117 | static unsigned int | |
1118 | rest_of_handle_fast_dce (void) | |
1119 | { | |
1120 | init_dce (true); | |
cc806ac1 RS |
1121 | fast_dce (false); |
1122 | fini_dce (true); | |
1123 | return 0; | |
1124 | } | |
1125 | ||
1126 | ||
1127 | /* Fast byte level DCE. */ | |
1128 | ||
8d074192 BS |
1129 | void |
1130 | run_word_dce (void) | |
cc806ac1 | 1131 | { |
25aef556 BS |
1132 | int old_flags; |
1133 | ||
1134 | if (!flag_dce) | |
1135 | return; | |
1136 | ||
8d074192 | 1137 | timevar_push (TV_DCE); |
25aef556 | 1138 | old_flags = df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
8d074192 | 1139 | df_word_lr_add_problem (); |
cc806ac1 RS |
1140 | init_dce (true); |
1141 | fast_dce (true); | |
2e6be65e | 1142 | fini_dce (true); |
25aef556 | 1143 | df_set_flags (old_flags); |
8d074192 | 1144 | timevar_pop (TV_DCE); |
6fb5fa3c DB |
1145 | } |
1146 | ||
1147 | ||
1148 | /* This is an internal call that is used by the df live register | |
1149 | problem to run fast dce as a side effect of creating the live | |
1150 | information. The stack is organized so that the lr problem is run, | |
1151 | this pass is run, which updates the live info and the df scanning | |
1152 | info, and then returns to allow the rest of the problems to be run. | |
1153 | ||
1154 | This can be called by elsewhere but it will not update the bit | |
2e6be65e | 1155 | vectors for any other problems than LR. */ |
6fb5fa3c DB |
1156 | |
1157 | void | |
1158 | run_fast_df_dce (void) | |
1159 | { | |
1160 | if (flag_dce) | |
1161 | { | |
1162 | /* If dce is able to delete something, it has to happen | |
1163 | immediately. Otherwise there will be problems handling the | |
1164 | eq_notes. */ | |
81f40b79 ILT |
1165 | int old_flags = |
1166 | df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); | |
1167 | ||
6fb5fa3c DB |
1168 | df_in_progress = true; |
1169 | rest_of_handle_fast_dce (); | |
2e6be65e EB |
1170 | df_in_progress = false; |
1171 | ||
6fb5fa3c DB |
1172 | df_set_flags (old_flags); |
1173 | } | |
1174 | } | |
1175 | ||
2e6be65e | 1176 | |
9ed7b221 EB |
1177 | /* Run a fast DCE pass. */ |
1178 | ||
1179 | void | |
1180 | run_fast_dce (void) | |
6fb5fa3c | 1181 | { |
9ed7b221 EB |
1182 | if (flag_dce) |
1183 | rest_of_handle_fast_dce (); | |
6fb5fa3c DB |
1184 | } |
1185 | ||
1186 | ||
9ed7b221 EB |
1187 | static bool |
1188 | gate_fast_dce (void) | |
6fb5fa3c | 1189 | { |
7d817ebc DE |
1190 | return optimize > 0 && flag_dce |
1191 | && dbg_cnt (dce_fast); | |
6fb5fa3c DB |
1192 | } |
1193 | ||
8ddbbcae | 1194 | struct rtl_opt_pass pass_fast_rtl_dce = |
6fb5fa3c | 1195 | { |
8ddbbcae JH |
1196 | { |
1197 | RTL_PASS, | |
5f57dccb | 1198 | "rtl_dce", /* name */ |
6fb5fa3c DB |
1199 | gate_fast_dce, /* gate */ |
1200 | rest_of_handle_fast_dce, /* execute */ | |
1201 | NULL, /* sub */ | |
1202 | NULL, /* next */ | |
1203 | 0, /* static_pass_number */ | |
1204 | TV_DCE, /* tv_id */ | |
1205 | 0, /* properties_required */ | |
1206 | 0, /* properties_provided */ | |
1207 | 0, /* properties_destroyed */ | |
1208 | 0, /* todo_flags_start */ | |
a36b8a1e | 1209 | TODO_df_finish | TODO_verify_rtl_sharing | |
8ddbbcae JH |
1210 | TODO_ggc_collect /* todo_flags_finish */ |
1211 | } | |
6fb5fa3c | 1212 | }; |