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Commit | Line | Data |
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6fb5fa3c | 1 | /* RTL dead code elimination. |
23a5b65a | 2 | Copyright (C) 2005-2014 Free Software Foundation, Inc. |
6fb5fa3c DB |
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 | |
9dcd6f09 | 8 | Software Foundation; either version 3, or (at your option) any later |
6fb5fa3c DB |
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 | |
9dcd6f09 NC |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
6fb5fa3c DB |
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" | |
35debead | 30 | #include "except.h" |
6fb5fa3c DB |
31 | #include "df.h" |
32 | #include "cselib.h" | |
33 | #include "dce.h" | |
08df6c0d | 34 | #include "valtrack.h" |
6fb5fa3c DB |
35 | #include "tree-pass.h" |
36 | #include "dbgcnt.h" | |
0196c95e | 37 | #include "tm_p.h" |
5936d944 | 38 | #include "emit-rtl.h" /* FIXME: Can go away once crtl is moved to rtl.h. */ |
6fb5fa3c | 39 | |
6fb5fa3c DB |
40 | |
41 | /* ------------------------------------------------------------------------- | |
42 | Core mark/delete routines | |
43 | ------------------------------------------------------------------------- */ | |
44 | ||
2e6be65e EB |
45 | /* True if we are invoked while the df engine is running; in this case, |
46 | we don't want to reenter it. */ | |
6fb5fa3c DB |
47 | static bool df_in_progress = false; |
48 | ||
2da02156 EB |
49 | /* True if we are allowed to alter the CFG in this pass. */ |
50 | static bool can_alter_cfg = false; | |
51 | ||
6fb5fa3c DB |
52 | /* Instructions that have been marked but whose dependencies have not |
53 | yet been processed. */ | |
9771b263 | 54 | static vec<rtx> worklist; |
6fb5fa3c | 55 | |
2e6be65e EB |
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. */ | |
6fb5fa3c DB |
60 | static bitmap_obstack dce_blocks_bitmap_obstack; |
61 | static bitmap_obstack dce_tmp_bitmap_obstack; | |
62 | ||
0196c95e | 63 | static bool find_call_stack_args (rtx, bool, bool, bitmap); |
6fb5fa3c | 64 | |
d4d7f1d1 RS |
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. */ | |
6fb5fa3c DB |
68 | |
69 | static bool | |
d4d7f1d1 | 70 | deletable_insn_p_1 (rtx body) |
6fb5fa3c | 71 | { |
6cad9859 | 72 | switch (GET_CODE (body)) |
6fb5fa3c | 73 | { |
6fb5fa3c DB |
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 | ||
d4d7f1d1 | 85 | default: |
1d65f45c | 86 | return !volatile_refs_p (body); |
d4d7f1d1 RS |
87 | } |
88 | } | |
89 | ||
2e6be65e | 90 | |
d4d7f1d1 RS |
91 | /* Return true if INSN is a normal instruction that can be deleted by |
92 | the DCE pass. */ | |
93 | ||
94 | static bool | |
0196c95e | 95 | deletable_insn_p (rtx insn, bool fast, bitmap arg_stores) |
d4d7f1d1 RS |
96 | { |
97 | rtx body, x; | |
98 | int i; | |
bfac633a | 99 | df_ref def; |
d4d7f1d1 | 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 | ||
211d71a7 | 124 | /* If INSN sets a global_reg, leave it untouched. */ |
bfac633a RS |
125 | FOR_EACH_INSN_DEF (def, insn) |
126 | if (HARD_REGISTER_NUM_P (DF_REF_REGNO (def)) | |
127 | && global_regs[DF_REF_REGNO (def)]) | |
211d71a7 SB |
128 | return false; |
129 | ||
d4d7f1d1 RS |
130 | body = PATTERN (insn); |
131 | switch (GET_CODE (body)) | |
132 | { | |
133 | case USE: | |
b5b8b0ac | 134 | case VAR_LOCATION: |
d4d7f1d1 RS |
135 | return false; |
136 | ||
6fb5fa3c DB |
137 | case CLOBBER: |
138 | if (fast) | |
139 | { | |
140 | /* A CLOBBER of a dead pseudo register serves no purpose. | |
141 | That is not necessarily true for hard registers until | |
142 | after reload. */ | |
6cad9859 | 143 | x = XEXP (body, 0); |
6fb5fa3c DB |
144 | return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed); |
145 | } | |
d4d7f1d1 | 146 | else |
6fb5fa3c DB |
147 | /* Because of the way that use-def chains are built, it is not |
148 | possible to tell if the clobber is dead because it can | |
149 | never be the target of a use-def chain. */ | |
150 | return false; | |
151 | ||
6cad9859 | 152 | case PARALLEL: |
d4d7f1d1 RS |
153 | for (i = XVECLEN (body, 0) - 1; i >= 0; i--) |
154 | if (!deletable_insn_p_1 (XVECEXP (body, 0, i))) | |
155 | return false; | |
156 | return true; | |
6cad9859 | 157 | |
6fb5fa3c | 158 | default: |
d4d7f1d1 | 159 | return deletable_insn_p_1 (body); |
6fb5fa3c DB |
160 | } |
161 | } | |
162 | ||
163 | ||
2e6be65e | 164 | /* Return true if INSN has been marked as needed. */ |
6fb5fa3c DB |
165 | |
166 | static inline int | |
167 | marked_insn_p (rtx insn) | |
168 | { | |
50e94c7e SB |
169 | /* Artificial defs are always needed and they do not have an insn. |
170 | We should never see them here. */ | |
171 | gcc_assert (insn); | |
d7c028c0 | 172 | return bitmap_bit_p (marked, INSN_UID (insn)); |
6fb5fa3c DB |
173 | } |
174 | ||
175 | ||
176 | /* If INSN has not yet been marked as needed, mark it now, and add it to | |
177 | the worklist. */ | |
178 | ||
179 | static void | |
180 | mark_insn (rtx insn, bool fast) | |
181 | { | |
182 | if (!marked_insn_p (insn)) | |
183 | { | |
184 | if (!fast) | |
9771b263 | 185 | worklist.safe_push (insn); |
d7c028c0 | 186 | bitmap_set_bit (marked, INSN_UID (insn)); |
6fb5fa3c DB |
187 | if (dump_file) |
188 | fprintf (dump_file, " Adding insn %d to worklist\n", INSN_UID (insn)); | |
0196c95e JJ |
189 | if (CALL_P (insn) |
190 | && !df_in_progress | |
191 | && !SIBLING_CALL_P (insn) | |
192 | && (RTL_CONST_OR_PURE_CALL_P (insn) | |
193 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
194 | find_call_stack_args (insn, true, fast, NULL); | |
6fb5fa3c DB |
195 | } |
196 | } | |
197 | ||
198 | ||
199 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
200 | instruction containing DEST. */ | |
201 | ||
202 | static void | |
7bc980e1 | 203 | mark_nonreg_stores_1 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
204 | { |
205 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
206 | mark_insn ((rtx) data, true); | |
207 | } | |
208 | ||
209 | ||
210 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
211 | instruction containing DEST. */ | |
212 | ||
213 | static void | |
7bc980e1 | 214 | mark_nonreg_stores_2 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
215 | { |
216 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
217 | mark_insn ((rtx) data, false); | |
218 | } | |
219 | ||
220 | ||
221 | /* Mark INSN if BODY stores to a non-register destination. */ | |
222 | ||
223 | static void | |
224 | mark_nonreg_stores (rtx body, rtx insn, bool fast) | |
225 | { | |
226 | if (fast) | |
227 | note_stores (body, mark_nonreg_stores_1, insn); | |
228 | else | |
229 | note_stores (body, mark_nonreg_stores_2, insn); | |
230 | } | |
231 | ||
232 | ||
2e0642cd JJ |
233 | /* Return true if store to MEM, starting OFF bytes from stack pointer, |
234 | is a call argument store, and clear corresponding bits from SP_BYTES | |
235 | bitmap if it is. */ | |
236 | ||
237 | static bool | |
238 | check_argument_store (rtx mem, HOST_WIDE_INT off, HOST_WIDE_INT min_sp_off, | |
239 | HOST_WIDE_INT max_sp_off, bitmap sp_bytes) | |
240 | { | |
241 | HOST_WIDE_INT byte; | |
242 | for (byte = off; byte < off + GET_MODE_SIZE (GET_MODE (mem)); byte++) | |
243 | { | |
244 | if (byte < min_sp_off | |
245 | || byte >= max_sp_off | |
246 | || !bitmap_clear_bit (sp_bytes, byte - min_sp_off)) | |
247 | return false; | |
248 | } | |
249 | return true; | |
250 | } | |
251 | ||
252 | ||
0196c95e JJ |
253 | /* Try to find all stack stores of CALL_INSN arguments if |
254 | ACCUMULATE_OUTGOING_ARGS. If all stack stores have been found | |
255 | and it is therefore safe to eliminate the call, return true, | |
256 | otherwise return false. This function should be first called | |
257 | with DO_MARK false, and only when the CALL_INSN is actually | |
258 | going to be marked called again with DO_MARK true. */ | |
259 | ||
260 | static bool | |
261 | find_call_stack_args (rtx call_insn, bool do_mark, bool fast, | |
262 | bitmap arg_stores) | |
263 | { | |
264 | rtx p, insn, prev_insn; | |
265 | bool ret; | |
266 | HOST_WIDE_INT min_sp_off, max_sp_off; | |
267 | bitmap sp_bytes; | |
268 | ||
269 | gcc_assert (CALL_P (call_insn)); | |
270 | if (!ACCUMULATE_OUTGOING_ARGS) | |
271 | return true; | |
272 | ||
273 | if (!do_mark) | |
274 | { | |
275 | gcc_assert (arg_stores); | |
276 | bitmap_clear (arg_stores); | |
277 | } | |
278 | ||
279 | min_sp_off = INTTYPE_MAXIMUM (HOST_WIDE_INT); | |
280 | max_sp_off = 0; | |
281 | ||
282 | /* First determine the minimum and maximum offset from sp for | |
283 | stored arguments. */ | |
284 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
285 | if (GET_CODE (XEXP (p, 0)) == USE | |
286 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
287 | { | |
f5541398 RS |
288 | rtx mem = XEXP (XEXP (p, 0), 0), addr; |
289 | HOST_WIDE_INT off = 0, size; | |
290 | if (!MEM_SIZE_KNOWN_P (mem)) | |
0196c95e | 291 | return false; |
f5541398 | 292 | size = MEM_SIZE (mem); |
0196c95e JJ |
293 | addr = XEXP (mem, 0); |
294 | if (GET_CODE (addr) == PLUS | |
295 | && REG_P (XEXP (addr, 0)) | |
296 | && CONST_INT_P (XEXP (addr, 1))) | |
297 | { | |
298 | off = INTVAL (XEXP (addr, 1)); | |
299 | addr = XEXP (addr, 0); | |
300 | } | |
301 | if (addr != stack_pointer_rtx) | |
302 | { | |
303 | if (!REG_P (addr)) | |
304 | return false; | |
305 | /* If not fast, use chains to see if addr wasn't set to | |
306 | sp + offset. */ | |
307 | if (!fast) | |
308 | { | |
bfac633a | 309 | df_ref use; |
0196c95e JJ |
310 | struct df_link *defs; |
311 | rtx set; | |
312 | ||
bfac633a RS |
313 | FOR_EACH_INSN_USE (use, call_insn) |
314 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
315 | break; |
316 | ||
bfac633a | 317 | if (use == NULL) |
0196c95e JJ |
318 | return false; |
319 | ||
bfac633a | 320 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
321 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
322 | break; | |
323 | ||
324 | if (defs == NULL) | |
325 | return false; | |
326 | ||
327 | set = single_set (DF_REF_INSN (defs->ref)); | |
328 | if (!set) | |
329 | return false; | |
330 | ||
331 | if (GET_CODE (SET_SRC (set)) != PLUS | |
332 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
333 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
334 | return false; | |
335 | ||
336 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
337 | } | |
338 | else | |
339 | return false; | |
340 | } | |
341 | min_sp_off = MIN (min_sp_off, off); | |
f5541398 | 342 | max_sp_off = MAX (max_sp_off, off + size); |
0196c95e JJ |
343 | } |
344 | ||
345 | if (min_sp_off >= max_sp_off) | |
346 | return true; | |
347 | sp_bytes = BITMAP_ALLOC (NULL); | |
348 | ||
349 | /* Set bits in SP_BYTES bitmap for bytes relative to sp + min_sp_off | |
350 | which contain arguments. Checking has been done in the previous | |
351 | loop. */ | |
352 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
353 | if (GET_CODE (XEXP (p, 0)) == USE | |
354 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
355 | { | |
356 | rtx mem = XEXP (XEXP (p, 0), 0), addr; | |
357 | HOST_WIDE_INT off = 0, byte; | |
358 | addr = XEXP (mem, 0); | |
359 | if (GET_CODE (addr) == PLUS | |
360 | && REG_P (XEXP (addr, 0)) | |
361 | && CONST_INT_P (XEXP (addr, 1))) | |
362 | { | |
363 | off = INTVAL (XEXP (addr, 1)); | |
364 | addr = XEXP (addr, 0); | |
365 | } | |
366 | if (addr != stack_pointer_rtx) | |
367 | { | |
bfac633a | 368 | df_ref use; |
0196c95e JJ |
369 | struct df_link *defs; |
370 | rtx set; | |
371 | ||
bfac633a RS |
372 | FOR_EACH_INSN_USE (use, call_insn) |
373 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
374 | break; |
375 | ||
bfac633a | 376 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
377 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
378 | break; | |
379 | ||
380 | set = single_set (DF_REF_INSN (defs->ref)); | |
381 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
382 | } | |
f5541398 | 383 | for (byte = off; byte < off + MEM_SIZE (mem); byte++) |
0196c95e | 384 | { |
821bb7f8 RG |
385 | if (!bitmap_set_bit (sp_bytes, byte - min_sp_off)) |
386 | gcc_unreachable (); | |
0196c95e JJ |
387 | } |
388 | } | |
389 | ||
390 | /* Walk backwards, looking for argument stores. The search stops | |
750900db | 391 | when seeing another call, sp adjustment or memory store other than |
0196c95e JJ |
392 | argument store. */ |
393 | ret = false; | |
394 | for (insn = PREV_INSN (call_insn); insn; insn = prev_insn) | |
395 | { | |
396 | rtx set, mem, addr; | |
2e0642cd | 397 | HOST_WIDE_INT off; |
0196c95e JJ |
398 | |
399 | if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn))) | |
400 | prev_insn = NULL_RTX; | |
401 | else | |
402 | prev_insn = PREV_INSN (insn); | |
403 | ||
404 | if (CALL_P (insn)) | |
405 | break; | |
406 | ||
2e0642cd | 407 | if (!NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
408 | continue; |
409 | ||
410 | set = single_set (insn); | |
411 | if (!set || SET_DEST (set) == stack_pointer_rtx) | |
412 | break; | |
413 | ||
414 | if (!MEM_P (SET_DEST (set))) | |
415 | continue; | |
416 | ||
417 | mem = SET_DEST (set); | |
418 | addr = XEXP (mem, 0); | |
419 | off = 0; | |
420 | if (GET_CODE (addr) == PLUS | |
421 | && REG_P (XEXP (addr, 0)) | |
422 | && CONST_INT_P (XEXP (addr, 1))) | |
423 | { | |
424 | off = INTVAL (XEXP (addr, 1)); | |
425 | addr = XEXP (addr, 0); | |
426 | } | |
427 | if (addr != stack_pointer_rtx) | |
428 | { | |
429 | if (!REG_P (addr)) | |
430 | break; | |
431 | if (!fast) | |
432 | { | |
bfac633a | 433 | df_ref use; |
0196c95e JJ |
434 | struct df_link *defs; |
435 | rtx set; | |
436 | ||
bfac633a RS |
437 | FOR_EACH_INSN_USE (use, insn) |
438 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
439 | break; |
440 | ||
bfac633a | 441 | if (use == NULL) |
0196c95e JJ |
442 | break; |
443 | ||
bfac633a | 444 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
445 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
446 | break; | |
447 | ||
448 | if (defs == NULL) | |
449 | break; | |
450 | ||
451 | set = single_set (DF_REF_INSN (defs->ref)); | |
452 | if (!set) | |
453 | break; | |
454 | ||
455 | if (GET_CODE (SET_SRC (set)) != PLUS | |
456 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
457 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
458 | break; | |
459 | ||
460 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
461 | } | |
462 | else | |
463 | break; | |
464 | } | |
465 | ||
2e0642cd JJ |
466 | if (GET_MODE_SIZE (GET_MODE (mem)) == 0 |
467 | || !check_argument_store (mem, off, min_sp_off, | |
468 | max_sp_off, sp_bytes)) | |
0196c95e JJ |
469 | break; |
470 | ||
0196c95e JJ |
471 | if (!deletable_insn_p (insn, fast, NULL)) |
472 | break; | |
473 | ||
474 | if (do_mark) | |
475 | mark_insn (insn, fast); | |
476 | else | |
477 | bitmap_set_bit (arg_stores, INSN_UID (insn)); | |
478 | ||
479 | if (bitmap_empty_p (sp_bytes)) | |
480 | { | |
481 | ret = true; | |
482 | break; | |
483 | } | |
484 | } | |
485 | ||
486 | BITMAP_FREE (sp_bytes); | |
487 | if (!ret && arg_stores) | |
488 | bitmap_clear (arg_stores); | |
489 | ||
490 | return ret; | |
491 | } | |
492 | ||
493 | ||
885c9b5d EB |
494 | /* Remove all REG_EQUAL and REG_EQUIV notes referring to the registers INSN |
495 | writes to. */ | |
6fb5fa3c DB |
496 | |
497 | static void | |
885c9b5d | 498 | remove_reg_equal_equiv_notes_for_defs (rtx insn) |
6fb5fa3c | 499 | { |
bfac633a | 500 | df_ref def; |
885c9b5d | 501 | |
bfac633a RS |
502 | FOR_EACH_INSN_DEF (def, insn) |
503 | remove_reg_equal_equiv_notes_for_regno (DF_REF_REGNO (def)); | |
6fb5fa3c DB |
504 | } |
505 | ||
a7a110bb AO |
506 | /* Scan all BBs for debug insns and reset those that reference values |
507 | defined in unmarked insns. */ | |
508 | ||
509 | static void | |
510 | reset_unmarked_insns_debug_uses (void) | |
511 | { | |
512 | basic_block bb; | |
513 | rtx insn, next; | |
514 | ||
4f42035e | 515 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
a7a110bb AO |
516 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
517 | if (DEBUG_INSN_P (insn)) | |
518 | { | |
bfac633a | 519 | df_ref use; |
a7a110bb | 520 | |
bfac633a | 521 | FOR_EACH_INSN_USE (use, insn) |
a7a110bb | 522 | { |
a7a110bb AO |
523 | struct df_link *defs; |
524 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
525 | { | |
8ced31fe | 526 | rtx ref_insn; |
a7a110bb AO |
527 | if (DF_REF_IS_ARTIFICIAL (defs->ref)) |
528 | continue; | |
8ced31fe JJ |
529 | ref_insn = DF_REF_INSN (defs->ref); |
530 | if (!marked_insn_p (ref_insn)) | |
a7a110bb AO |
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); | |
8ced31fe | 539 | break; |
a7a110bb AO |
540 | } |
541 | } | |
542 | } | |
6fb5fa3c | 543 | |
9ed7b221 | 544 | /* Delete every instruction that hasn't been marked. */ |
6fb5fa3c DB |
545 | |
546 | static void | |
547 | delete_unmarked_insns (void) | |
548 | { | |
549 | basic_block bb; | |
550 | rtx insn, next; | |
5ba5ab9b | 551 | bool must_clean = false; |
6fb5fa3c | 552 | |
4f42035e | 553 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
cd3f1729 | 554 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
a7a110bb | 555 | if (NONDEBUG_INSN_P (insn)) |
6fb5fa3c | 556 | { |
9ed7b221 | 557 | /* Always delete no-op moves. */ |
6fb5fa3c | 558 | if (noop_move_p (insn)) |
9ed7b221 EB |
559 | ; |
560 | ||
9ed7b221 | 561 | /* Otherwise rely only on the DCE algorithm. */ |
6fb5fa3c DB |
562 | else if (marked_insn_p (insn)) |
563 | continue; | |
564 | ||
cd3f1729 KZ |
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. */ | |
6fb5fa3c DB |
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 | ||
885c9b5d | 589 | /* Before we delete the insn we have to remove the REG_EQUAL notes |
9ed7b221 | 590 | for the destination regs in order to avoid dangling notes. */ |
885c9b5d | 591 | remove_reg_equal_equiv_notes_for_defs (insn); |
6fb5fa3c | 592 | |
5ba5ab9b KZ |
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 | ||
9ed7b221 | 599 | /* Now delete the insn. */ |
6fb5fa3c | 600 | delete_insn_and_edges (insn); |
6fb5fa3c | 601 | } |
5ba5ab9b KZ |
602 | |
603 | /* Deleted a pure or const call. */ | |
604 | if (must_clean) | |
605 | delete_unreachable_blocks (); | |
6fb5fa3c DB |
606 | } |
607 | ||
608 | ||
6fb5fa3c DB |
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; | |
0196c95e JJ |
617 | rtx insn, prev; |
618 | bitmap arg_stores = NULL; | |
619 | ||
6fb5fa3c DB |
620 | if (dump_file) |
621 | fprintf (dump_file, "Finding needed instructions:\n"); | |
0196c95e JJ |
622 | |
623 | if (!df_in_progress && ACCUMULATE_OUTGOING_ARGS) | |
624 | arg_stores = BITMAP_ALLOC (NULL); | |
625 | ||
11cd3bed | 626 | FOR_EACH_BB_FN (bb, cfun) |
0196c95e JJ |
627 | { |
628 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev) | |
a7a110bb | 629 | if (NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
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); | |
6fb5fa3c DB |
648 | |
649 | if (dump_file) | |
650 | fprintf (dump_file, "Finished finding needed instructions:\n"); | |
651 | } | |
652 | ||
653 | ||
654 | /* UD-based DSE routines. */ | |
655 | ||
6ed3da00 | 656 | /* Mark instructions that define artificially-used registers, such as |
6fb5fa3c DB |
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; | |
57512f53 | 664 | df_ref *use_rec; |
6fb5fa3c | 665 | |
04a90bec | 666 | FOR_ALL_BB_FN (bb, cfun) |
6fb5fa3c | 667 | { |
b8698a0f | 668 | for (use_rec = df_get_artificial_uses (bb->index); |
6fb5fa3c DB |
669 | *use_rec; use_rec++) |
670 | for (defs = DF_REF_CHAIN (*use_rec); defs; defs = defs->next) | |
50e94c7e SB |
671 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
672 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
673 | } |
674 | } | |
675 | ||
2e6be65e | 676 | |
6fb5fa3c DB |
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; | |
bfac633a | 683 | df_ref use; |
6fb5fa3c | 684 | |
b5b8b0ac AO |
685 | if (DEBUG_INSN_P (insn)) |
686 | return; | |
687 | ||
bfac633a | 688 | FOR_EACH_INSN_USE (use, insn) |
6fb5fa3c | 689 | { |
6fb5fa3c DB |
690 | if (dump_file) |
691 | { | |
692 | fprintf (dump_file, "Processing use of "); | |
693 | print_simple_rtl (dump_file, DF_REF_REG (use)); | |
694 | fprintf (dump_file, " in insn %d:\n", INSN_UID (insn)); | |
695 | } | |
696 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
50e94c7e SB |
697 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
698 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
699 | } |
700 | } | |
701 | ||
702 | ||
2e6be65e EB |
703 | /* Initialize global variables for a new DCE pass. */ |
704 | ||
6fb5fa3c | 705 | static void |
2e6be65e EB |
706 | init_dce (bool fast) |
707 | { | |
708 | if (!df_in_progress) | |
709 | { | |
710 | if (!fast) | |
7b19209f SB |
711 | { |
712 | df_set_flags (DF_RD_PRUNE_DEAD_DEFS); | |
713 | df_chain_add_problem (DF_UD_CHAIN); | |
714 | } | |
2e6be65e EB |
715 | df_analyze (); |
716 | } | |
717 | ||
718 | if (dump_file) | |
719 | df_dump (dump_file); | |
720 | ||
721 | if (fast) | |
722 | { | |
723 | bitmap_obstack_initialize (&dce_blocks_bitmap_obstack); | |
724 | bitmap_obstack_initialize (&dce_tmp_bitmap_obstack); | |
2da02156 | 725 | can_alter_cfg = false; |
2e6be65e | 726 | } |
2da02156 EB |
727 | else |
728 | can_alter_cfg = true; | |
2e6be65e EB |
729 | |
730 | marked = sbitmap_alloc (get_max_uid () + 1); | |
f61e445a | 731 | bitmap_clear (marked); |
2e6be65e EB |
732 | } |
733 | ||
734 | ||
735 | /* Free the data allocated by init_dce. */ | |
736 | ||
737 | static void | |
738 | fini_dce (bool fast) | |
6fb5fa3c DB |
739 | { |
740 | sbitmap_free (marked); | |
2e6be65e EB |
741 | |
742 | if (fast) | |
743 | { | |
744 | bitmap_obstack_release (&dce_blocks_bitmap_obstack); | |
745 | bitmap_obstack_release (&dce_tmp_bitmap_obstack); | |
746 | } | |
6fb5fa3c DB |
747 | } |
748 | ||
749 | ||
750 | /* UD-chain based DCE. */ | |
751 | ||
752 | static unsigned int | |
753 | rest_of_handle_ud_dce (void) | |
754 | { | |
755 | rtx insn; | |
756 | ||
6fb5fa3c DB |
757 | init_dce (false); |
758 | ||
759 | prescan_insns_for_dce (false); | |
760 | mark_artificial_uses (); | |
9771b263 | 761 | while (worklist.length () > 0) |
6fb5fa3c | 762 | { |
9771b263 | 763 | insn = worklist.pop (); |
6fb5fa3c DB |
764 | mark_reg_dependencies (insn); |
765 | } | |
9771b263 | 766 | worklist.release (); |
2e6be65e | 767 | |
a7a110bb AO |
768 | if (MAY_HAVE_DEBUG_INSNS) |
769 | reset_unmarked_insns_debug_uses (); | |
770 | ||
6fb5fa3c DB |
771 | /* Before any insns are deleted, we must remove the chains since |
772 | they are not bidirectional. */ | |
773 | df_remove_problem (df_chain); | |
774 | delete_unmarked_insns (); | |
775 | ||
2e6be65e | 776 | fini_dce (false); |
6fb5fa3c DB |
777 | return 0; |
778 | } | |
779 | ||
780 | ||
27a4cd48 DM |
781 | namespace { |
782 | ||
783 | const pass_data pass_data_ud_rtl_dce = | |
6fb5fa3c | 784 | { |
27a4cd48 DM |
785 | RTL_PASS, /* type */ |
786 | "ud_dce", /* name */ | |
787 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
788 | true, /* has_execute */ |
789 | TV_DCE, /* tv_id */ | |
790 | 0, /* properties_required */ | |
791 | 0, /* properties_provided */ | |
792 | 0, /* properties_destroyed */ | |
793 | 0, /* todo_flags_start */ | |
3bea341f | 794 | TODO_df_finish, /* todo_flags_finish */ |
6fb5fa3c DB |
795 | }; |
796 | ||
27a4cd48 DM |
797 | class pass_ud_rtl_dce : public rtl_opt_pass |
798 | { | |
799 | public: | |
c3284718 RS |
800 | pass_ud_rtl_dce (gcc::context *ctxt) |
801 | : rtl_opt_pass (pass_data_ud_rtl_dce, ctxt) | |
27a4cd48 DM |
802 | {} |
803 | ||
804 | /* opt_pass methods: */ | |
1a3d085c TS |
805 | virtual bool gate (function *) |
806 | { | |
807 | return optimize > 1 && flag_dce && dbg_cnt (dce_ud); | |
808 | } | |
809 | ||
be55bfe6 TS |
810 | virtual unsigned int execute (function *) |
811 | { | |
812 | return rest_of_handle_ud_dce (); | |
813 | } | |
27a4cd48 DM |
814 | |
815 | }; // class pass_ud_rtl_dce | |
816 | ||
817 | } // anon namespace | |
818 | ||
819 | rtl_opt_pass * | |
820 | make_pass_ud_rtl_dce (gcc::context *ctxt) | |
821 | { | |
822 | return new pass_ud_rtl_dce (ctxt); | |
823 | } | |
824 | ||
2e6be65e | 825 | |
6fb5fa3c DB |
826 | /* ------------------------------------------------------------------------- |
827 | Fast DCE functions | |
828 | ------------------------------------------------------------------------- */ | |
829 | ||
cc806ac1 RS |
830 | /* Process basic block BB. Return true if the live_in set has |
831 | changed. REDO_OUT is true if the info at the bottom of the block | |
832 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
833 | artificial uses. Track global substitution of uses of dead pseudos |
834 | in debug insns using GLOBAL_DEBUG. */ | |
6fb5fa3c DB |
835 | |
836 | static bool | |
e9f950ba AO |
837 | word_dce_process_block (basic_block bb, bool redo_out, |
838 | struct dead_debug_global *global_debug) | |
6fb5fa3c DB |
839 | { |
840 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
841 | rtx insn; | |
842 | bool block_changed; | |
e9f950ba | 843 | struct dead_debug_local debug; |
6fb5fa3c DB |
844 | |
845 | if (redo_out) | |
846 | { | |
847 | /* Need to redo the live_out set of this block if when one of | |
848 | the succs of this block has had a change in it live in | |
849 | set. */ | |
850 | edge e; | |
851 | edge_iterator ei; | |
8d074192 BS |
852 | df_confluence_function_n con_fun_n = df_word_lr->problem->con_fun_n; |
853 | bitmap_clear (DF_WORD_LR_OUT (bb)); | |
6fb5fa3c DB |
854 | FOR_EACH_EDGE (e, ei, bb->succs) |
855 | (*con_fun_n) (e); | |
856 | } | |
857 | ||
858 | if (dump_file) | |
859 | { | |
860 | fprintf (dump_file, "processing block %d live out = ", bb->index); | |
8d074192 | 861 | df_print_word_regset (dump_file, DF_WORD_LR_OUT (bb)); |
6fb5fa3c DB |
862 | } |
863 | ||
8d074192 | 864 | bitmap_copy (local_live, DF_WORD_LR_OUT (bb)); |
e9f950ba | 865 | dead_debug_local_init (&debug, NULL, global_debug); |
cc806ac1 RS |
866 | |
867 | FOR_BB_INSNS_REVERSE (bb, insn) | |
1adbb361 AO |
868 | if (DEBUG_INSN_P (insn)) |
869 | { | |
bfac633a RS |
870 | df_ref use; |
871 | FOR_EACH_INSN_USE (use, insn) | |
872 | if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER | |
873 | && (GET_MODE_SIZE (GET_MODE (DF_REF_REAL_REG (use))) | |
1adbb361 | 874 | == 2 * UNITS_PER_WORD) |
bfac633a RS |
875 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use)) |
876 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use) + 1)) | |
877 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
1adbb361 AO |
878 | } |
879 | else if (INSN_P (insn)) | |
cc806ac1 | 880 | { |
8d074192 | 881 | bool any_changed; |
1adbb361 | 882 | |
cc806ac1 RS |
883 | /* No matter if the instruction is needed or not, we remove |
884 | any regno in the defs from the live set. */ | |
8d074192 BS |
885 | any_changed = df_word_lr_simulate_defs (insn, local_live); |
886 | if (any_changed) | |
887 | mark_insn (insn, true); | |
cc806ac1 RS |
888 | |
889 | /* On the other hand, we do not allow the dead uses to set | |
890 | anything in local_live. */ | |
891 | if (marked_insn_p (insn)) | |
8d074192 | 892 | df_word_lr_simulate_uses (insn, local_live); |
6f9e260c | 893 | |
39bc0f01 | 894 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
895 | insns. We may have to emit a debug temp even if the insn |
896 | was marked, in case the debug use was after the point of | |
897 | death. */ | |
898 | if (debug.used && !bitmap_empty_p (debug.used)) | |
1adbb361 | 899 | { |
bfac633a | 900 | df_ref def; |
1adbb361 | 901 | |
bfac633a RS |
902 | FOR_EACH_INSN_DEF (def, insn) |
903 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
85d87497 JJ |
904 | marked_insn_p (insn) |
905 | && !control_flow_insn_p (insn) | |
906 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
907 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
1adbb361 AO |
908 | } |
909 | ||
cc806ac1 RS |
910 | if (dump_file) |
911 | { | |
b8698a0f | 912 | fprintf (dump_file, "finished processing insn %d live out = ", |
cc806ac1 | 913 | INSN_UID (insn)); |
8d074192 | 914 | df_print_word_regset (dump_file, local_live); |
cc806ac1 RS |
915 | } |
916 | } | |
b8698a0f | 917 | |
8d074192 | 918 | block_changed = !bitmap_equal_p (local_live, DF_WORD_LR_IN (bb)); |
cc806ac1 | 919 | if (block_changed) |
8d074192 BS |
920 | bitmap_copy (DF_WORD_LR_IN (bb), local_live); |
921 | ||
e9f950ba | 922 | dead_debug_local_finish (&debug, NULL); |
cc806ac1 RS |
923 | BITMAP_FREE (local_live); |
924 | return block_changed; | |
925 | } | |
926 | ||
927 | ||
928 | /* Process basic block BB. Return true if the live_in set has | |
929 | changed. REDO_OUT is true if the info at the bottom of the block | |
930 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
931 | artificial uses. Track global substitution of uses of dead pseudos |
932 | in debug insns using GLOBAL_DEBUG. */ | |
cc806ac1 RS |
933 | |
934 | static bool | |
e9f950ba AO |
935 | dce_process_block (basic_block bb, bool redo_out, bitmap au, |
936 | struct dead_debug_global *global_debug) | |
cc806ac1 RS |
937 | { |
938 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
939 | rtx insn; | |
940 | bool block_changed; | |
bfac633a | 941 | df_ref def; |
e9f950ba | 942 | struct dead_debug_local debug; |
6fb5fa3c | 943 | |
cc806ac1 | 944 | if (redo_out) |
6fb5fa3c | 945 | { |
cc806ac1 RS |
946 | /* Need to redo the live_out set of this block if when one of |
947 | the succs of this block has had a change in it live in | |
948 | set. */ | |
949 | edge e; | |
950 | edge_iterator ei; | |
951 | df_confluence_function_n con_fun_n = df_lr->problem->con_fun_n; | |
952 | bitmap_clear (DF_LR_OUT (bb)); | |
953 | FOR_EACH_EDGE (e, ei, bb->succs) | |
954 | (*con_fun_n) (e); | |
6fb5fa3c DB |
955 | } |
956 | ||
cc806ac1 | 957 | if (dump_file) |
6fb5fa3c | 958 | { |
fafe34f9 | 959 | fprintf (dump_file, "processing block %d lr out = ", bb->index); |
cc806ac1 | 960 | df_print_regset (dump_file, DF_LR_OUT (bb)); |
6fb5fa3c DB |
961 | } |
962 | ||
cc806ac1 RS |
963 | bitmap_copy (local_live, DF_LR_OUT (bb)); |
964 | ||
02b47899 | 965 | df_simulate_initialize_backwards (bb, local_live); |
e9f950ba | 966 | dead_debug_local_init (&debug, NULL, global_debug); |
541d3103 | 967 | |
6fb5fa3c | 968 | FOR_BB_INSNS_REVERSE (bb, insn) |
1adbb361 AO |
969 | if (DEBUG_INSN_P (insn)) |
970 | { | |
bfac633a RS |
971 | df_ref use; |
972 | FOR_EACH_INSN_USE (use, insn) | |
973 | if (!bitmap_bit_p (local_live, DF_REF_REGNO (use)) | |
974 | && !bitmap_bit_p (au, DF_REF_REGNO (use))) | |
975 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
1adbb361 AO |
976 | } |
977 | else if (INSN_P (insn)) | |
6fb5fa3c | 978 | { |
f251709a | 979 | bool needed = marked_insn_p (insn); |
9ed7b221 EB |
980 | |
981 | /* The insn is needed if there is someone who uses the output. */ | |
f251709a | 982 | if (!needed) |
bfac633a RS |
983 | FOR_EACH_INSN_DEF (def, insn) |
984 | if (bitmap_bit_p (local_live, DF_REF_REGNO (def)) | |
985 | || bitmap_bit_p (au, DF_REF_REGNO (def))) | |
39bc0f01 AO |
986 | { |
987 | needed = true; | |
988 | mark_insn (insn, true); | |
989 | break; | |
990 | } | |
b8698a0f | 991 | |
6fb5fa3c DB |
992 | /* No matter if the instruction is needed or not, we remove |
993 | any regno in the defs from the live set. */ | |
994 | df_simulate_defs (insn, local_live); | |
995 | ||
996 | /* On the other hand, we do not allow the dead uses to set | |
997 | anything in local_live. */ | |
f251709a | 998 | if (needed) |
6fb5fa3c | 999 | df_simulate_uses (insn, local_live); |
6f9e260c | 1000 | |
39bc0f01 | 1001 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
1002 | insns. We may have to emit a debug temp even if the insn |
1003 | was marked, in case the debug use was after the point of | |
1004 | death. */ | |
1005 | if (debug.used && !bitmap_empty_p (debug.used)) | |
bfac633a RS |
1006 | FOR_EACH_INSN_DEF (def, insn) |
1007 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
85d87497 JJ |
1008 | needed && !control_flow_insn_p (insn) |
1009 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
1010 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
6fb5fa3c | 1011 | } |
b8698a0f | 1012 | |
e9f950ba | 1013 | dead_debug_local_finish (&debug, NULL); |
02b47899 | 1014 | df_simulate_finalize_backwards (bb, local_live); |
6fb5fa3c DB |
1015 | |
1016 | block_changed = !bitmap_equal_p (local_live, DF_LR_IN (bb)); | |
1017 | if (block_changed) | |
1018 | bitmap_copy (DF_LR_IN (bb), local_live); | |
1019 | ||
1020 | BITMAP_FREE (local_live); | |
1021 | return block_changed; | |
1022 | } | |
1023 | ||
2e6be65e | 1024 | |
8d074192 BS |
1025 | /* Perform fast DCE once initialization is done. If WORD_LEVEL is |
1026 | true, use the word level dce, otherwise do it at the pseudo | |
cc806ac1 | 1027 | level. */ |
2e6be65e | 1028 | |
6fb5fa3c | 1029 | static void |
8d074192 | 1030 | fast_dce (bool word_level) |
6fb5fa3c DB |
1031 | { |
1032 | int *postorder = df_get_postorder (DF_BACKWARD); | |
1033 | int n_blocks = df_get_n_blocks (DF_BACKWARD); | |
6fb5fa3c DB |
1034 | /* The set of blocks that have been seen on this iteration. */ |
1035 | bitmap processed = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1036 | /* The set of blocks that need to have the out vectors reset because | |
1037 | the in of one of their successors has changed. */ | |
1038 | bitmap redo_out = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1039 | bitmap all_blocks = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1040 | bool global_changed = true; | |
cc806ac1 RS |
1041 | |
1042 | /* These regs are considered always live so if they end up dying | |
1043 | because of some def, we need to bring the back again. Calling | |
1044 | df_simulate_fixup_sets has the disadvantage of calling | |
1045 | bb_has_eh_pred once per insn, so we cache the information | |
1046 | here. */ | |
a7e3698d JH |
1047 | bitmap au = &df->regular_block_artificial_uses; |
1048 | bitmap au_eh = &df->eh_block_artificial_uses; | |
9ed7b221 | 1049 | int i; |
e9f950ba | 1050 | struct dead_debug_global global_debug; |
6fb5fa3c DB |
1051 | |
1052 | prescan_insns_for_dce (true); | |
1053 | ||
1054 | for (i = 0; i < n_blocks; i++) | |
1055 | bitmap_set_bit (all_blocks, postorder[i]); | |
1056 | ||
e9f950ba AO |
1057 | dead_debug_global_init (&global_debug, NULL); |
1058 | ||
6fb5fa3c DB |
1059 | while (global_changed) |
1060 | { | |
1061 | global_changed = false; | |
9ed7b221 | 1062 | |
6fb5fa3c DB |
1063 | for (i = 0; i < n_blocks; i++) |
1064 | { | |
1065 | int index = postorder[i]; | |
06e28de2 | 1066 | basic_block bb = BASIC_BLOCK_FOR_FN (cfun, index); |
6fb5fa3c DB |
1067 | bool local_changed; |
1068 | ||
1069 | if (index < NUM_FIXED_BLOCKS) | |
1070 | { | |
1071 | bitmap_set_bit (processed, index); | |
1072 | continue; | |
1073 | } | |
1074 | ||
8d074192 | 1075 | if (word_level) |
b8698a0f | 1076 | local_changed |
e9f950ba AO |
1077 | = word_dce_process_block (bb, bitmap_bit_p (redo_out, index), |
1078 | &global_debug); | |
cc806ac1 | 1079 | else |
b8698a0f | 1080 | local_changed |
cc806ac1 | 1081 | = dce_process_block (bb, bitmap_bit_p (redo_out, index), |
e9f950ba AO |
1082 | bb_has_eh_pred (bb) ? au_eh : au, |
1083 | &global_debug); | |
6fb5fa3c | 1084 | bitmap_set_bit (processed, index); |
b8698a0f | 1085 | |
6fb5fa3c DB |
1086 | if (local_changed) |
1087 | { | |
1088 | edge e; | |
1089 | edge_iterator ei; | |
1090 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1091 | if (bitmap_bit_p (processed, e->src->index)) | |
1092 | /* Be tricky about when we need to iterate the | |
1093 | analysis. We only have redo the analysis if the | |
1094 | bitmaps change at the top of a block that is the | |
1095 | entry to a loop. */ | |
1096 | global_changed = true; | |
1097 | else | |
1098 | bitmap_set_bit (redo_out, e->src->index); | |
1099 | } | |
1100 | } | |
b8698a0f | 1101 | |
6fb5fa3c DB |
1102 | if (global_changed) |
1103 | { | |
1104 | /* Turn off the RUN_DCE flag to prevent recursive calls to | |
1105 | dce. */ | |
1106 | int old_flag = df_clear_flags (DF_LR_RUN_DCE); | |
1107 | ||
1108 | /* So something was deleted that requires a redo. Do it on | |
1109 | the cheap. */ | |
1110 | delete_unmarked_insns (); | |
f61e445a | 1111 | bitmap_clear (marked); |
6fb5fa3c DB |
1112 | bitmap_clear (processed); |
1113 | bitmap_clear (redo_out); | |
b8698a0f | 1114 | |
6fb5fa3c DB |
1115 | /* We do not need to rescan any instructions. We only need |
1116 | to redo the dataflow equations for the blocks that had a | |
1117 | change at the top of the block. Then we need to redo the | |
b8698a0f | 1118 | iteration. */ |
8d074192 BS |
1119 | if (word_level) |
1120 | df_analyze_problem (df_word_lr, all_blocks, postorder, n_blocks); | |
cc806ac1 RS |
1121 | else |
1122 | df_analyze_problem (df_lr, all_blocks, postorder, n_blocks); | |
6fb5fa3c DB |
1123 | |
1124 | if (old_flag & DF_LR_RUN_DCE) | |
1125 | df_set_flags (DF_LR_RUN_DCE); | |
9ed7b221 | 1126 | |
6fb5fa3c DB |
1127 | prescan_insns_for_dce (true); |
1128 | } | |
6fb5fa3c DB |
1129 | } |
1130 | ||
e9f950ba AO |
1131 | dead_debug_global_finish (&global_debug, NULL); |
1132 | ||
6fb5fa3c DB |
1133 | delete_unmarked_insns (); |
1134 | ||
1135 | BITMAP_FREE (processed); | |
1136 | BITMAP_FREE (redo_out); | |
1137 | BITMAP_FREE (all_blocks); | |
1138 | } | |
1139 | ||
1140 | ||
cc806ac1 | 1141 | /* Fast register level DCE. */ |
6fb5fa3c DB |
1142 | |
1143 | static unsigned int | |
1144 | rest_of_handle_fast_dce (void) | |
1145 | { | |
1146 | init_dce (true); | |
cc806ac1 RS |
1147 | fast_dce (false); |
1148 | fini_dce (true); | |
1149 | return 0; | |
1150 | } | |
1151 | ||
1152 | ||
1153 | /* Fast byte level DCE. */ | |
1154 | ||
8d074192 BS |
1155 | void |
1156 | run_word_dce (void) | |
cc806ac1 | 1157 | { |
25aef556 BS |
1158 | int old_flags; |
1159 | ||
1160 | if (!flag_dce) | |
1161 | return; | |
1162 | ||
8d074192 | 1163 | timevar_push (TV_DCE); |
25aef556 | 1164 | old_flags = df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
8d074192 | 1165 | df_word_lr_add_problem (); |
cc806ac1 RS |
1166 | init_dce (true); |
1167 | fast_dce (true); | |
2e6be65e | 1168 | fini_dce (true); |
25aef556 | 1169 | df_set_flags (old_flags); |
8d074192 | 1170 | timevar_pop (TV_DCE); |
6fb5fa3c DB |
1171 | } |
1172 | ||
1173 | ||
1174 | /* This is an internal call that is used by the df live register | |
1175 | problem to run fast dce as a side effect of creating the live | |
1176 | information. The stack is organized so that the lr problem is run, | |
1177 | this pass is run, which updates the live info and the df scanning | |
1178 | info, and then returns to allow the rest of the problems to be run. | |
1179 | ||
1180 | This can be called by elsewhere but it will not update the bit | |
2e6be65e | 1181 | vectors for any other problems than LR. */ |
6fb5fa3c DB |
1182 | |
1183 | void | |
1184 | run_fast_df_dce (void) | |
1185 | { | |
1186 | if (flag_dce) | |
1187 | { | |
1188 | /* If dce is able to delete something, it has to happen | |
1189 | immediately. Otherwise there will be problems handling the | |
1190 | eq_notes. */ | |
81f40b79 ILT |
1191 | int old_flags = |
1192 | df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); | |
1193 | ||
6fb5fa3c DB |
1194 | df_in_progress = true; |
1195 | rest_of_handle_fast_dce (); | |
2e6be65e EB |
1196 | df_in_progress = false; |
1197 | ||
6fb5fa3c DB |
1198 | df_set_flags (old_flags); |
1199 | } | |
1200 | } | |
1201 | ||
2e6be65e | 1202 | |
9ed7b221 EB |
1203 | /* Run a fast DCE pass. */ |
1204 | ||
1205 | void | |
1206 | run_fast_dce (void) | |
6fb5fa3c | 1207 | { |
9ed7b221 EB |
1208 | if (flag_dce) |
1209 | rest_of_handle_fast_dce (); | |
6fb5fa3c DB |
1210 | } |
1211 | ||
1212 | ||
27a4cd48 DM |
1213 | namespace { |
1214 | ||
1215 | const pass_data pass_data_fast_rtl_dce = | |
6fb5fa3c | 1216 | { |
27a4cd48 DM |
1217 | RTL_PASS, /* type */ |
1218 | "rtl_dce", /* name */ | |
1219 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
1220 | true, /* has_execute */ |
1221 | TV_DCE, /* tv_id */ | |
1222 | 0, /* properties_required */ | |
1223 | 0, /* properties_provided */ | |
1224 | 0, /* properties_destroyed */ | |
1225 | 0, /* todo_flags_start */ | |
3bea341f | 1226 | TODO_df_finish, /* todo_flags_finish */ |
6fb5fa3c | 1227 | }; |
27a4cd48 DM |
1228 | |
1229 | class pass_fast_rtl_dce : public rtl_opt_pass | |
1230 | { | |
1231 | public: | |
c3284718 RS |
1232 | pass_fast_rtl_dce (gcc::context *ctxt) |
1233 | : rtl_opt_pass (pass_data_fast_rtl_dce, ctxt) | |
27a4cd48 DM |
1234 | {} |
1235 | ||
1236 | /* opt_pass methods: */ | |
1a3d085c TS |
1237 | virtual bool gate (function *) |
1238 | { | |
1239 | return optimize > 0 && flag_dce && dbg_cnt (dce_fast); | |
1240 | } | |
1241 | ||
be55bfe6 TS |
1242 | virtual unsigned int execute (function *) |
1243 | { | |
1244 | return rest_of_handle_fast_dce (); | |
1245 | } | |
27a4cd48 DM |
1246 | |
1247 | }; // class pass_fast_rtl_dce | |
1248 | ||
1249 | } // anon namespace | |
1250 | ||
1251 | rtl_opt_pass * | |
1252 | make_pass_fast_rtl_dce (gcc::context *ctxt) | |
1253 | { | |
1254 | return new pass_fast_rtl_dce (ctxt); | |
1255 | } |