]>
Commit | Line | Data |
---|---|---|
3072d30e | 1 | /* RTL dead code elimination. |
3aea1f79 | 2 | Copyright (C) 2005-2014 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" |
94ea8568 | 31 | #include "dominance.h" |
32 | #include "cfg.h" | |
33 | #include "cfgrtl.h" | |
34 | #include "cfgbuild.h" | |
35 | #include "cfgcleanup.h" | |
36 | #include "predict.h" | |
37 | #include "basic-block.h" | |
3072d30e | 38 | #include "df.h" |
39 | #include "cselib.h" | |
40 | #include "dce.h" | |
e6637753 | 41 | #include "valtrack.h" |
3072d30e | 42 | #include "tree-pass.h" |
43 | #include "dbgcnt.h" | |
eb940a48 | 44 | #include "tm_p.h" |
06f9d6ef | 45 | #include "emit-rtl.h" /* FIXME: Can go away once crtl is moved to rtl.h. */ |
3072d30e | 46 | |
3072d30e | 47 | |
48 | /* ------------------------------------------------------------------------- | |
49 | Core mark/delete routines | |
50 | ------------------------------------------------------------------------- */ | |
51 | ||
3c6c0b50 | 52 | /* True if we are invoked while the df engine is running; in this case, |
53 | we don't want to reenter it. */ | |
3072d30e | 54 | static bool df_in_progress = false; |
55 | ||
bc0dfc8d | 56 | /* True if we are allowed to alter the CFG in this pass. */ |
57 | static bool can_alter_cfg = false; | |
58 | ||
3072d30e | 59 | /* Instructions that have been marked but whose dependencies have not |
60 | yet been processed. */ | |
57b7551c | 61 | static vec<rtx_insn *> worklist; |
3072d30e | 62 | |
3c6c0b50 | 63 | /* Bitmap of instructions marked as needed indexed by INSN_UID. */ |
64 | static sbitmap marked; | |
65 | ||
66 | /* Bitmap obstacks used for block processing by the fast algorithm. */ | |
3072d30e | 67 | static bitmap_obstack dce_blocks_bitmap_obstack; |
68 | static bitmap_obstack dce_tmp_bitmap_obstack; | |
69 | ||
57b7551c | 70 | static bool find_call_stack_args (rtx_call_insn *, bool, bool, bitmap); |
3072d30e | 71 | |
ec2fc131 | 72 | /* A subroutine for which BODY is part of the instruction being tested; |
73 | either the top-level pattern, or an element of a PARALLEL. The | |
74 | instruction is known not to be a bare USE or CLOBBER. */ | |
3072d30e | 75 | |
76 | static bool | |
ec2fc131 | 77 | deletable_insn_p_1 (rtx body) |
3072d30e | 78 | { |
d49ffcf4 | 79 | switch (GET_CODE (body)) |
3072d30e | 80 | { |
3072d30e | 81 | case PREFETCH: |
82 | case TRAP_IF: | |
83 | /* The UNSPEC case was added here because the ia-64 claims that | |
84 | USEs do not work after reload and generates UNSPECS rather | |
85 | than USEs. Since dce is run after reload we need to avoid | |
86 | deleting these even if they are dead. If it turns out that | |
87 | USEs really do work after reload, the ia-64 should be | |
88 | changed, and the UNSPEC case can be removed. */ | |
89 | case UNSPEC: | |
90 | return false; | |
91 | ||
ec2fc131 | 92 | default: |
e38def9c | 93 | return !volatile_refs_p (body); |
ec2fc131 | 94 | } |
95 | } | |
96 | ||
3c6c0b50 | 97 | |
ec2fc131 | 98 | /* Return true if INSN is a normal instruction that can be deleted by |
99 | the DCE pass. */ | |
100 | ||
101 | static bool | |
57b7551c | 102 | deletable_insn_p (rtx_insn *insn, bool fast, bitmap arg_stores) |
ec2fc131 | 103 | { |
104 | rtx body, x; | |
105 | int i; | |
be10bb5a | 106 | df_ref def; |
ec2fc131 | 107 | |
0b7b55ea | 108 | if (CALL_P (insn) |
109 | /* We cannot delete calls inside of the recursive dce because | |
110 | this may cause basic blocks to be deleted and this messes up | |
111 | the rest of the stack of optimization passes. */ | |
112 | && (!df_in_progress) | |
113 | /* We cannot delete pure or const sibling calls because it is | |
114 | hard to see the result. */ | |
9c2a0c05 | 115 | && (!SIBLING_CALL_P (insn)) |
0b7b55ea | 116 | /* We can delete dead const or pure calls as long as they do not |
117 | infinite loop. */ | |
9c2a0c05 | 118 | && (RTL_CONST_OR_PURE_CALL_P (insn) |
119 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
57b7551c | 120 | return find_call_stack_args (as_a <rtx_call_insn *> (insn), false, |
121 | fast, arg_stores); | |
9c2a0c05 | 122 | |
827c9a9e | 123 | /* Don't delete jumps, notes and the like. */ |
124 | if (!NONJUMP_INSN_P (insn)) | |
125 | return false; | |
126 | ||
bc0dfc8d | 127 | /* Don't delete insns that may throw if we cannot do so. */ |
128 | if (!(cfun->can_delete_dead_exceptions && can_alter_cfg) | |
129 | && !insn_nothrow_p (insn)) | |
827c9a9e | 130 | return false; |
131 | ||
925e8609 | 132 | /* If INSN sets a global_reg, leave it untouched. */ |
be10bb5a | 133 | FOR_EACH_INSN_DEF (def, insn) |
134 | if (HARD_REGISTER_NUM_P (DF_REF_REGNO (def)) | |
135 | && global_regs[DF_REF_REGNO (def)]) | |
925e8609 | 136 | return false; |
0d1f9fde | 137 | /* Initialization of pseudo PIC register should never be removed. */ |
138 | else if (DF_REF_REG (def) == pic_offset_table_rtx | |
139 | && REGNO (pic_offset_table_rtx) >= FIRST_PSEUDO_REGISTER) | |
140 | return false; | |
925e8609 | 141 | |
ec2fc131 | 142 | body = PATTERN (insn); |
143 | switch (GET_CODE (body)) | |
144 | { | |
145 | case USE: | |
9845d120 | 146 | case VAR_LOCATION: |
ec2fc131 | 147 | return false; |
148 | ||
3072d30e | 149 | case CLOBBER: |
150 | if (fast) | |
151 | { | |
152 | /* A CLOBBER of a dead pseudo register serves no purpose. | |
153 | That is not necessarily true for hard registers until | |
154 | after reload. */ | |
d49ffcf4 | 155 | x = XEXP (body, 0); |
3072d30e | 156 | return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed); |
157 | } | |
ec2fc131 | 158 | else |
3072d30e | 159 | /* Because of the way that use-def chains are built, it is not |
160 | possible to tell if the clobber is dead because it can | |
161 | never be the target of a use-def chain. */ | |
162 | return false; | |
163 | ||
d49ffcf4 | 164 | case PARALLEL: |
ec2fc131 | 165 | for (i = XVECLEN (body, 0) - 1; i >= 0; i--) |
166 | if (!deletable_insn_p_1 (XVECEXP (body, 0, i))) | |
167 | return false; | |
168 | return true; | |
d49ffcf4 | 169 | |
3072d30e | 170 | default: |
ec2fc131 | 171 | return deletable_insn_p_1 (body); |
3072d30e | 172 | } |
173 | } | |
174 | ||
175 | ||
3c6c0b50 | 176 | /* Return true if INSN has been marked as needed. */ |
3072d30e | 177 | |
178 | static inline int | |
57b7551c | 179 | marked_insn_p (rtx_insn *insn) |
3072d30e | 180 | { |
158b6cc9 | 181 | /* Artificial defs are always needed and they do not have an insn. |
182 | We should never see them here. */ | |
183 | gcc_assert (insn); | |
08b7917c | 184 | return bitmap_bit_p (marked, INSN_UID (insn)); |
3072d30e | 185 | } |
186 | ||
187 | ||
188 | /* If INSN has not yet been marked as needed, mark it now, and add it to | |
189 | the worklist. */ | |
190 | ||
191 | static void | |
57b7551c | 192 | mark_insn (rtx_insn *insn, bool fast) |
3072d30e | 193 | { |
194 | if (!marked_insn_p (insn)) | |
195 | { | |
196 | if (!fast) | |
f1f41a6c | 197 | worklist.safe_push (insn); |
08b7917c | 198 | bitmap_set_bit (marked, INSN_UID (insn)); |
3072d30e | 199 | if (dump_file) |
200 | fprintf (dump_file, " Adding insn %d to worklist\n", INSN_UID (insn)); | |
eb940a48 | 201 | if (CALL_P (insn) |
202 | && !df_in_progress | |
203 | && !SIBLING_CALL_P (insn) | |
204 | && (RTL_CONST_OR_PURE_CALL_P (insn) | |
205 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
57b7551c | 206 | find_call_stack_args (as_a <rtx_call_insn *> (insn), true, fast, NULL); |
3072d30e | 207 | } |
208 | } | |
209 | ||
210 | ||
211 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
212 | instruction containing DEST. */ | |
213 | ||
214 | static void | |
81a410b1 | 215 | mark_nonreg_stores_1 (rtx dest, const_rtx pattern, void *data) |
3072d30e | 216 | { |
217 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
57b7551c | 218 | mark_insn ((rtx_insn *) data, true); |
3072d30e | 219 | } |
220 | ||
221 | ||
222 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
223 | instruction containing DEST. */ | |
224 | ||
225 | static void | |
81a410b1 | 226 | mark_nonreg_stores_2 (rtx dest, const_rtx pattern, void *data) |
3072d30e | 227 | { |
228 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
57b7551c | 229 | mark_insn ((rtx_insn *) data, false); |
3072d30e | 230 | } |
231 | ||
232 | ||
233 | /* Mark INSN if BODY stores to a non-register destination. */ | |
234 | ||
235 | static void | |
57b7551c | 236 | mark_nonreg_stores (rtx body, rtx_insn *insn, bool fast) |
3072d30e | 237 | { |
238 | if (fast) | |
239 | note_stores (body, mark_nonreg_stores_1, insn); | |
240 | else | |
241 | note_stores (body, mark_nonreg_stores_2, insn); | |
242 | } | |
243 | ||
244 | ||
85e2842b | 245 | /* Return true if store to MEM, starting OFF bytes from stack pointer, |
246 | is a call argument store, and clear corresponding bits from SP_BYTES | |
247 | bitmap if it is. */ | |
248 | ||
249 | static bool | |
250 | check_argument_store (rtx mem, HOST_WIDE_INT off, HOST_WIDE_INT min_sp_off, | |
251 | HOST_WIDE_INT max_sp_off, bitmap sp_bytes) | |
252 | { | |
253 | HOST_WIDE_INT byte; | |
254 | for (byte = off; byte < off + GET_MODE_SIZE (GET_MODE (mem)); byte++) | |
255 | { | |
256 | if (byte < min_sp_off | |
257 | || byte >= max_sp_off | |
258 | || !bitmap_clear_bit (sp_bytes, byte - min_sp_off)) | |
259 | return false; | |
260 | } | |
261 | return true; | |
262 | } | |
263 | ||
264 | ||
eb940a48 | 265 | /* Try to find all stack stores of CALL_INSN arguments if |
266 | ACCUMULATE_OUTGOING_ARGS. If all stack stores have been found | |
267 | and it is therefore safe to eliminate the call, return true, | |
268 | otherwise return false. This function should be first called | |
269 | with DO_MARK false, and only when the CALL_INSN is actually | |
270 | going to be marked called again with DO_MARK true. */ | |
271 | ||
272 | static bool | |
57b7551c | 273 | find_call_stack_args (rtx_call_insn *call_insn, bool do_mark, bool fast, |
eb940a48 | 274 | bitmap arg_stores) |
275 | { | |
57b7551c | 276 | rtx p; |
277 | rtx_insn *insn, *prev_insn; | |
eb940a48 | 278 | bool ret; |
279 | HOST_WIDE_INT min_sp_off, max_sp_off; | |
280 | bitmap sp_bytes; | |
281 | ||
282 | gcc_assert (CALL_P (call_insn)); | |
283 | if (!ACCUMULATE_OUTGOING_ARGS) | |
284 | return true; | |
285 | ||
286 | if (!do_mark) | |
287 | { | |
288 | gcc_assert (arg_stores); | |
289 | bitmap_clear (arg_stores); | |
290 | } | |
291 | ||
292 | min_sp_off = INTTYPE_MAXIMUM (HOST_WIDE_INT); | |
293 | max_sp_off = 0; | |
294 | ||
295 | /* First determine the minimum and maximum offset from sp for | |
296 | stored arguments. */ | |
297 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
298 | if (GET_CODE (XEXP (p, 0)) == USE | |
299 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
300 | { | |
5b2a69fa | 301 | rtx mem = XEXP (XEXP (p, 0), 0), addr; |
302 | HOST_WIDE_INT off = 0, size; | |
303 | if (!MEM_SIZE_KNOWN_P (mem)) | |
eb940a48 | 304 | return false; |
5b2a69fa | 305 | size = MEM_SIZE (mem); |
eb940a48 | 306 | addr = XEXP (mem, 0); |
307 | if (GET_CODE (addr) == PLUS | |
308 | && REG_P (XEXP (addr, 0)) | |
309 | && CONST_INT_P (XEXP (addr, 1))) | |
310 | { | |
311 | off = INTVAL (XEXP (addr, 1)); | |
312 | addr = XEXP (addr, 0); | |
313 | } | |
314 | if (addr != stack_pointer_rtx) | |
315 | { | |
316 | if (!REG_P (addr)) | |
317 | return false; | |
318 | /* If not fast, use chains to see if addr wasn't set to | |
319 | sp + offset. */ | |
320 | if (!fast) | |
321 | { | |
be10bb5a | 322 | df_ref use; |
eb940a48 | 323 | struct df_link *defs; |
324 | rtx set; | |
325 | ||
be10bb5a | 326 | FOR_EACH_INSN_USE (use, call_insn) |
327 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
eb940a48 | 328 | break; |
329 | ||
be10bb5a | 330 | if (use == NULL) |
eb940a48 | 331 | return false; |
332 | ||
be10bb5a | 333 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
eb940a48 | 334 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
335 | break; | |
336 | ||
337 | if (defs == NULL) | |
338 | return false; | |
339 | ||
340 | set = single_set (DF_REF_INSN (defs->ref)); | |
341 | if (!set) | |
342 | return false; | |
343 | ||
344 | if (GET_CODE (SET_SRC (set)) != PLUS | |
345 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
346 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
347 | return false; | |
348 | ||
349 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
350 | } | |
351 | else | |
352 | return false; | |
353 | } | |
354 | min_sp_off = MIN (min_sp_off, off); | |
5b2a69fa | 355 | max_sp_off = MAX (max_sp_off, off + size); |
eb940a48 | 356 | } |
357 | ||
358 | if (min_sp_off >= max_sp_off) | |
359 | return true; | |
360 | sp_bytes = BITMAP_ALLOC (NULL); | |
361 | ||
362 | /* Set bits in SP_BYTES bitmap for bytes relative to sp + min_sp_off | |
363 | which contain arguments. Checking has been done in the previous | |
364 | loop. */ | |
365 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
366 | if (GET_CODE (XEXP (p, 0)) == USE | |
367 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
368 | { | |
369 | rtx mem = XEXP (XEXP (p, 0), 0), addr; | |
370 | HOST_WIDE_INT off = 0, byte; | |
371 | addr = XEXP (mem, 0); | |
372 | if (GET_CODE (addr) == PLUS | |
373 | && REG_P (XEXP (addr, 0)) | |
374 | && CONST_INT_P (XEXP (addr, 1))) | |
375 | { | |
376 | off = INTVAL (XEXP (addr, 1)); | |
377 | addr = XEXP (addr, 0); | |
378 | } | |
379 | if (addr != stack_pointer_rtx) | |
380 | { | |
be10bb5a | 381 | df_ref use; |
eb940a48 | 382 | struct df_link *defs; |
383 | rtx set; | |
384 | ||
be10bb5a | 385 | FOR_EACH_INSN_USE (use, call_insn) |
386 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
eb940a48 | 387 | break; |
388 | ||
be10bb5a | 389 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
eb940a48 | 390 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
391 | break; | |
392 | ||
393 | set = single_set (DF_REF_INSN (defs->ref)); | |
394 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
395 | } | |
5b2a69fa | 396 | for (byte = off; byte < off + MEM_SIZE (mem); byte++) |
eb940a48 | 397 | { |
2adb8813 | 398 | if (!bitmap_set_bit (sp_bytes, byte - min_sp_off)) |
399 | gcc_unreachable (); | |
eb940a48 | 400 | } |
401 | } | |
402 | ||
403 | /* Walk backwards, looking for argument stores. The search stops | |
66aca59d | 404 | when seeing another call, sp adjustment or memory store other than |
eb940a48 | 405 | argument store. */ |
406 | ret = false; | |
407 | for (insn = PREV_INSN (call_insn); insn; insn = prev_insn) | |
408 | { | |
409 | rtx set, mem, addr; | |
85e2842b | 410 | HOST_WIDE_INT off; |
eb940a48 | 411 | |
412 | if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn))) | |
57b7551c | 413 | prev_insn = NULL; |
eb940a48 | 414 | else |
415 | prev_insn = PREV_INSN (insn); | |
416 | ||
417 | if (CALL_P (insn)) | |
418 | break; | |
419 | ||
85e2842b | 420 | if (!NONDEBUG_INSN_P (insn)) |
eb940a48 | 421 | continue; |
422 | ||
423 | set = single_set (insn); | |
424 | if (!set || SET_DEST (set) == stack_pointer_rtx) | |
425 | break; | |
426 | ||
427 | if (!MEM_P (SET_DEST (set))) | |
428 | continue; | |
429 | ||
430 | mem = SET_DEST (set); | |
431 | addr = XEXP (mem, 0); | |
432 | off = 0; | |
433 | if (GET_CODE (addr) == PLUS | |
434 | && REG_P (XEXP (addr, 0)) | |
435 | && CONST_INT_P (XEXP (addr, 1))) | |
436 | { | |
437 | off = INTVAL (XEXP (addr, 1)); | |
438 | addr = XEXP (addr, 0); | |
439 | } | |
440 | if (addr != stack_pointer_rtx) | |
441 | { | |
442 | if (!REG_P (addr)) | |
443 | break; | |
444 | if (!fast) | |
445 | { | |
be10bb5a | 446 | df_ref use; |
eb940a48 | 447 | struct df_link *defs; |
448 | rtx set; | |
449 | ||
be10bb5a | 450 | FOR_EACH_INSN_USE (use, insn) |
451 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
eb940a48 | 452 | break; |
453 | ||
be10bb5a | 454 | if (use == NULL) |
eb940a48 | 455 | break; |
456 | ||
be10bb5a | 457 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
eb940a48 | 458 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
459 | break; | |
460 | ||
461 | if (defs == NULL) | |
462 | break; | |
463 | ||
464 | set = single_set (DF_REF_INSN (defs->ref)); | |
465 | if (!set) | |
466 | break; | |
467 | ||
468 | if (GET_CODE (SET_SRC (set)) != PLUS | |
469 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
470 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
471 | break; | |
472 | ||
473 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
474 | } | |
475 | else | |
476 | break; | |
477 | } | |
478 | ||
85e2842b | 479 | if (GET_MODE_SIZE (GET_MODE (mem)) == 0 |
480 | || !check_argument_store (mem, off, min_sp_off, | |
481 | max_sp_off, sp_bytes)) | |
eb940a48 | 482 | break; |
483 | ||
eb940a48 | 484 | if (!deletable_insn_p (insn, fast, NULL)) |
485 | break; | |
486 | ||
487 | if (do_mark) | |
488 | mark_insn (insn, fast); | |
489 | else | |
490 | bitmap_set_bit (arg_stores, INSN_UID (insn)); | |
491 | ||
492 | if (bitmap_empty_p (sp_bytes)) | |
493 | { | |
494 | ret = true; | |
495 | break; | |
496 | } | |
497 | } | |
498 | ||
499 | BITMAP_FREE (sp_bytes); | |
500 | if (!ret && arg_stores) | |
501 | bitmap_clear (arg_stores); | |
502 | ||
503 | return ret; | |
504 | } | |
505 | ||
506 | ||
09669349 | 507 | /* Remove all REG_EQUAL and REG_EQUIV notes referring to the registers INSN |
508 | writes to. */ | |
3072d30e | 509 | |
510 | static void | |
57b7551c | 511 | remove_reg_equal_equiv_notes_for_defs (rtx_insn *insn) |
3072d30e | 512 | { |
be10bb5a | 513 | df_ref def; |
09669349 | 514 | |
be10bb5a | 515 | FOR_EACH_INSN_DEF (def, insn) |
516 | remove_reg_equal_equiv_notes_for_regno (DF_REF_REGNO (def)); | |
3072d30e | 517 | } |
518 | ||
a6aa49aa | 519 | /* Scan all BBs for debug insns and reset those that reference values |
520 | defined in unmarked insns. */ | |
521 | ||
522 | static void | |
523 | reset_unmarked_insns_debug_uses (void) | |
524 | { | |
525 | basic_block bb; | |
57b7551c | 526 | rtx_insn *insn, *next; |
a6aa49aa | 527 | |
7a46197b | 528 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
a6aa49aa | 529 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
530 | if (DEBUG_INSN_P (insn)) | |
531 | { | |
be10bb5a | 532 | df_ref use; |
a6aa49aa | 533 | |
be10bb5a | 534 | FOR_EACH_INSN_USE (use, insn) |
a6aa49aa | 535 | { |
a6aa49aa | 536 | struct df_link *defs; |
537 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
538 | { | |
57b7551c | 539 | rtx_insn *ref_insn; |
a6aa49aa | 540 | if (DF_REF_IS_ARTIFICIAL (defs->ref)) |
541 | continue; | |
5af2c7fc | 542 | ref_insn = DF_REF_INSN (defs->ref); |
543 | if (!marked_insn_p (ref_insn)) | |
a6aa49aa | 544 | break; |
545 | } | |
546 | if (!defs) | |
547 | continue; | |
548 | /* ??? FIXME could we propagate the values assigned to | |
549 | each of the DEFs? */ | |
550 | INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC (); | |
551 | df_insn_rescan_debug_internal (insn); | |
5af2c7fc | 552 | break; |
a6aa49aa | 553 | } |
554 | } | |
555 | } | |
3072d30e | 556 | |
ebc94641 | 557 | /* Delete every instruction that hasn't been marked. */ |
3072d30e | 558 | |
559 | static void | |
560 | delete_unmarked_insns (void) | |
561 | { | |
562 | basic_block bb; | |
57b7551c | 563 | rtx_insn *insn, *next; |
0b7b55ea | 564 | bool must_clean = false; |
3072d30e | 565 | |
7a46197b | 566 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
cff725a2 | 567 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
a6aa49aa | 568 | if (NONDEBUG_INSN_P (insn)) |
3072d30e | 569 | { |
ebc94641 | 570 | /* Always delete no-op moves. */ |
3072d30e | 571 | if (noop_move_p (insn)) |
ebc94641 | 572 | ; |
573 | ||
ebc94641 | 574 | /* Otherwise rely only on the DCE algorithm. */ |
3072d30e | 575 | else if (marked_insn_p (insn)) |
576 | continue; | |
577 | ||
cff725a2 | 578 | /* Beware that reaching a dbg counter limit here can result |
579 | in miscompiled file. This occurs when a group of insns | |
580 | must be deleted together, typically because the kept insn | |
581 | depends on the output from the deleted insn. Deleting | |
582 | this insns in reverse order (both at the bb level and | |
583 | when looking at the blocks) minimizes this, but does not | |
584 | eliminate it, since it is possible for the using insn to | |
585 | be top of a block and the producer to be at the bottom of | |
586 | the block. However, in most cases this will only result | |
587 | in an uninitialized use of an insn that is dead anyway. | |
588 | ||
589 | However, there is one rare case that will cause a | |
590 | miscompile: deletion of non-looping pure and constant | |
591 | calls on a machine where ACCUMULATE_OUTGOING_ARGS is true. | |
592 | In this case it is possible to remove the call, but leave | |
593 | the argument pushes to the stack. Because of the changes | |
594 | to the stack pointer, this will almost always lead to a | |
595 | miscompile. */ | |
3072d30e | 596 | if (!dbg_cnt (dce)) |
597 | continue; | |
598 | ||
599 | if (dump_file) | |
600 | fprintf (dump_file, "DCE: Deleting insn %d\n", INSN_UID (insn)); | |
601 | ||
09669349 | 602 | /* Before we delete the insn we have to remove the REG_EQUAL notes |
ebc94641 | 603 | for the destination regs in order to avoid dangling notes. */ |
09669349 | 604 | remove_reg_equal_equiv_notes_for_defs (insn); |
3072d30e | 605 | |
0b7b55ea | 606 | /* If a pure or const call is deleted, this may make the cfg |
607 | have unreachable blocks. We rememeber this and call | |
608 | delete_unreachable_blocks at the end. */ | |
609 | if (CALL_P (insn)) | |
610 | must_clean = true; | |
611 | ||
ebc94641 | 612 | /* Now delete the insn. */ |
3072d30e | 613 | delete_insn_and_edges (insn); |
3072d30e | 614 | } |
0b7b55ea | 615 | |
616 | /* Deleted a pure or const call. */ | |
617 | if (must_clean) | |
618 | delete_unreachable_blocks (); | |
3072d30e | 619 | } |
620 | ||
621 | ||
3072d30e | 622 | /* Go through the instructions and mark those whose necessity is not |
623 | dependent on inter-instruction information. Make sure all other | |
624 | instructions are not marked. */ | |
625 | ||
626 | static void | |
627 | prescan_insns_for_dce (bool fast) | |
628 | { | |
629 | basic_block bb; | |
57b7551c | 630 | rtx_insn *insn, *prev; |
eb940a48 | 631 | bitmap arg_stores = NULL; |
632 | ||
3072d30e | 633 | if (dump_file) |
634 | fprintf (dump_file, "Finding needed instructions:\n"); | |
eb940a48 | 635 | |
636 | if (!df_in_progress && ACCUMULATE_OUTGOING_ARGS) | |
637 | arg_stores = BITMAP_ALLOC (NULL); | |
638 | ||
fc00614f | 639 | FOR_EACH_BB_FN (bb, cfun) |
eb940a48 | 640 | { |
641 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev) | |
a6aa49aa | 642 | if (NONDEBUG_INSN_P (insn)) |
eb940a48 | 643 | { |
644 | /* Don't mark argument stores now. They will be marked | |
645 | if needed when the associated CALL is marked. */ | |
646 | if (arg_stores && bitmap_bit_p (arg_stores, INSN_UID (insn))) | |
647 | continue; | |
648 | if (deletable_insn_p (insn, fast, arg_stores)) | |
649 | mark_nonreg_stores (PATTERN (insn), insn, fast); | |
650 | else | |
651 | mark_insn (insn, fast); | |
652 | } | |
653 | /* find_call_stack_args only looks at argument stores in the | |
654 | same bb. */ | |
655 | if (arg_stores) | |
656 | bitmap_clear (arg_stores); | |
657 | } | |
658 | ||
659 | if (arg_stores) | |
660 | BITMAP_FREE (arg_stores); | |
3072d30e | 661 | |
662 | if (dump_file) | |
663 | fprintf (dump_file, "Finished finding needed instructions:\n"); | |
664 | } | |
665 | ||
666 | ||
667 | /* UD-based DSE routines. */ | |
668 | ||
6dfdc153 | 669 | /* Mark instructions that define artificially-used registers, such as |
3072d30e | 670 | the frame pointer and the stack pointer. */ |
671 | ||
672 | static void | |
673 | mark_artificial_uses (void) | |
674 | { | |
675 | basic_block bb; | |
676 | struct df_link *defs; | |
f1c570a6 | 677 | df_ref use; |
3072d30e | 678 | |
ed7d889a | 679 | FOR_ALL_BB_FN (bb, cfun) |
f1c570a6 | 680 | FOR_EACH_ARTIFICIAL_USE (use, bb->index) |
681 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
682 | if (!DF_REF_IS_ARTIFICIAL (defs->ref)) | |
683 | mark_insn (DF_REF_INSN (defs->ref), false); | |
3072d30e | 684 | } |
685 | ||
3c6c0b50 | 686 | |
3072d30e | 687 | /* Mark every instruction that defines a register value that INSN uses. */ |
688 | ||
689 | static void | |
57b7551c | 690 | mark_reg_dependencies (rtx_insn *insn) |
3072d30e | 691 | { |
692 | struct df_link *defs; | |
be10bb5a | 693 | df_ref use; |
3072d30e | 694 | |
9845d120 | 695 | if (DEBUG_INSN_P (insn)) |
696 | return; | |
697 | ||
be10bb5a | 698 | FOR_EACH_INSN_USE (use, insn) |
3072d30e | 699 | { |
3072d30e | 700 | if (dump_file) |
701 | { | |
702 | fprintf (dump_file, "Processing use of "); | |
703 | print_simple_rtl (dump_file, DF_REF_REG (use)); | |
704 | fprintf (dump_file, " in insn %d:\n", INSN_UID (insn)); | |
705 | } | |
706 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
158b6cc9 | 707 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
708 | mark_insn (DF_REF_INSN (defs->ref), false); | |
3072d30e | 709 | } |
710 | } | |
711 | ||
712 | ||
3c6c0b50 | 713 | /* Initialize global variables for a new DCE pass. */ |
714 | ||
3072d30e | 715 | static void |
3c6c0b50 | 716 | init_dce (bool fast) |
717 | { | |
718 | if (!df_in_progress) | |
719 | { | |
720 | if (!fast) | |
ea9538fb | 721 | { |
722 | df_set_flags (DF_RD_PRUNE_DEAD_DEFS); | |
723 | df_chain_add_problem (DF_UD_CHAIN); | |
724 | } | |
3c6c0b50 | 725 | df_analyze (); |
726 | } | |
727 | ||
728 | if (dump_file) | |
729 | df_dump (dump_file); | |
730 | ||
731 | if (fast) | |
732 | { | |
733 | bitmap_obstack_initialize (&dce_blocks_bitmap_obstack); | |
734 | bitmap_obstack_initialize (&dce_tmp_bitmap_obstack); | |
bc0dfc8d | 735 | can_alter_cfg = false; |
3c6c0b50 | 736 | } |
bc0dfc8d | 737 | else |
738 | can_alter_cfg = true; | |
3c6c0b50 | 739 | |
740 | marked = sbitmap_alloc (get_max_uid () + 1); | |
53c5d9d4 | 741 | bitmap_clear (marked); |
3c6c0b50 | 742 | } |
743 | ||
744 | ||
745 | /* Free the data allocated by init_dce. */ | |
746 | ||
747 | static void | |
748 | fini_dce (bool fast) | |
3072d30e | 749 | { |
750 | sbitmap_free (marked); | |
3c6c0b50 | 751 | |
752 | if (fast) | |
753 | { | |
754 | bitmap_obstack_release (&dce_blocks_bitmap_obstack); | |
755 | bitmap_obstack_release (&dce_tmp_bitmap_obstack); | |
756 | } | |
3072d30e | 757 | } |
758 | ||
759 | ||
760 | /* UD-chain based DCE. */ | |
761 | ||
762 | static unsigned int | |
763 | rest_of_handle_ud_dce (void) | |
764 | { | |
57b7551c | 765 | rtx_insn *insn; |
3072d30e | 766 | |
3072d30e | 767 | init_dce (false); |
768 | ||
769 | prescan_insns_for_dce (false); | |
770 | mark_artificial_uses (); | |
f1f41a6c | 771 | while (worklist.length () > 0) |
3072d30e | 772 | { |
f1f41a6c | 773 | insn = worklist.pop (); |
3072d30e | 774 | mark_reg_dependencies (insn); |
775 | } | |
f1f41a6c | 776 | worklist.release (); |
3c6c0b50 | 777 | |
a6aa49aa | 778 | if (MAY_HAVE_DEBUG_INSNS) |
779 | reset_unmarked_insns_debug_uses (); | |
780 | ||
3072d30e | 781 | /* Before any insns are deleted, we must remove the chains since |
782 | they are not bidirectional. */ | |
783 | df_remove_problem (df_chain); | |
784 | delete_unmarked_insns (); | |
785 | ||
3c6c0b50 | 786 | fini_dce (false); |
3072d30e | 787 | return 0; |
788 | } | |
789 | ||
790 | ||
cbe8bda8 | 791 | namespace { |
792 | ||
793 | const pass_data pass_data_ud_rtl_dce = | |
3072d30e | 794 | { |
cbe8bda8 | 795 | RTL_PASS, /* type */ |
796 | "ud_dce", /* name */ | |
797 | OPTGROUP_NONE, /* optinfo_flags */ | |
cbe8bda8 | 798 | TV_DCE, /* tv_id */ |
799 | 0, /* properties_required */ | |
800 | 0, /* properties_provided */ | |
801 | 0, /* properties_destroyed */ | |
802 | 0, /* todo_flags_start */ | |
8b88439e | 803 | TODO_df_finish, /* todo_flags_finish */ |
3072d30e | 804 | }; |
805 | ||
cbe8bda8 | 806 | class pass_ud_rtl_dce : public rtl_opt_pass |
807 | { | |
808 | public: | |
9af5ce0c | 809 | pass_ud_rtl_dce (gcc::context *ctxt) |
810 | : rtl_opt_pass (pass_data_ud_rtl_dce, ctxt) | |
cbe8bda8 | 811 | {} |
812 | ||
813 | /* opt_pass methods: */ | |
31315c24 | 814 | virtual bool gate (function *) |
815 | { | |
816 | return optimize > 1 && flag_dce && dbg_cnt (dce_ud); | |
817 | } | |
818 | ||
65b0537f | 819 | virtual unsigned int execute (function *) |
820 | { | |
821 | return rest_of_handle_ud_dce (); | |
822 | } | |
cbe8bda8 | 823 | |
824 | }; // class pass_ud_rtl_dce | |
825 | ||
826 | } // anon namespace | |
827 | ||
828 | rtl_opt_pass * | |
829 | make_pass_ud_rtl_dce (gcc::context *ctxt) | |
830 | { | |
831 | return new pass_ud_rtl_dce (ctxt); | |
832 | } | |
833 | ||
3c6c0b50 | 834 | |
3072d30e | 835 | /* ------------------------------------------------------------------------- |
836 | Fast DCE functions | |
837 | ------------------------------------------------------------------------- */ | |
838 | ||
bf1f8fbc | 839 | /* Process basic block BB. Return true if the live_in set has |
840 | changed. REDO_OUT is true if the info at the bottom of the block | |
841 | needs to be recalculated before starting. AU is the proper set of | |
dcd028e1 | 842 | artificial uses. Track global substitution of uses of dead pseudos |
843 | in debug insns using GLOBAL_DEBUG. */ | |
3072d30e | 844 | |
845 | static bool | |
dcd028e1 | 846 | word_dce_process_block (basic_block bb, bool redo_out, |
847 | struct dead_debug_global *global_debug) | |
3072d30e | 848 | { |
849 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
57b7551c | 850 | rtx_insn *insn; |
3072d30e | 851 | bool block_changed; |
dcd028e1 | 852 | struct dead_debug_local debug; |
3072d30e | 853 | |
854 | if (redo_out) | |
855 | { | |
856 | /* Need to redo the live_out set of this block if when one of | |
857 | the succs of this block has had a change in it live in | |
858 | set. */ | |
859 | edge e; | |
860 | edge_iterator ei; | |
0e8e9be3 | 861 | df_confluence_function_n con_fun_n = df_word_lr->problem->con_fun_n; |
862 | bitmap_clear (DF_WORD_LR_OUT (bb)); | |
3072d30e | 863 | FOR_EACH_EDGE (e, ei, bb->succs) |
864 | (*con_fun_n) (e); | |
865 | } | |
866 | ||
867 | if (dump_file) | |
868 | { | |
869 | fprintf (dump_file, "processing block %d live out = ", bb->index); | |
0e8e9be3 | 870 | df_print_word_regset (dump_file, DF_WORD_LR_OUT (bb)); |
3072d30e | 871 | } |
872 | ||
0e8e9be3 | 873 | bitmap_copy (local_live, DF_WORD_LR_OUT (bb)); |
dcd028e1 | 874 | dead_debug_local_init (&debug, NULL, global_debug); |
bf1f8fbc | 875 | |
876 | FOR_BB_INSNS_REVERSE (bb, insn) | |
2abb79fc | 877 | if (DEBUG_INSN_P (insn)) |
878 | { | |
be10bb5a | 879 | df_ref use; |
880 | FOR_EACH_INSN_USE (use, insn) | |
881 | if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER | |
882 | && (GET_MODE_SIZE (GET_MODE (DF_REF_REAL_REG (use))) | |
2abb79fc | 883 | == 2 * UNITS_PER_WORD) |
be10bb5a | 884 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use)) |
885 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use) + 1)) | |
886 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
2abb79fc | 887 | } |
888 | else if (INSN_P (insn)) | |
bf1f8fbc | 889 | { |
0e8e9be3 | 890 | bool any_changed; |
2abb79fc | 891 | |
bf1f8fbc | 892 | /* No matter if the instruction is needed or not, we remove |
893 | any regno in the defs from the live set. */ | |
0e8e9be3 | 894 | any_changed = df_word_lr_simulate_defs (insn, local_live); |
895 | if (any_changed) | |
896 | mark_insn (insn, true); | |
bf1f8fbc | 897 | |
898 | /* On the other hand, we do not allow the dead uses to set | |
899 | anything in local_live. */ | |
900 | if (marked_insn_p (insn)) | |
0e8e9be3 | 901 | df_word_lr_simulate_uses (insn, local_live); |
704e91bd | 902 | |
5ea3fd4b | 903 | /* Insert debug temps for dead REGs used in subsequent debug |
704e91bd | 904 | insns. We may have to emit a debug temp even if the insn |
905 | was marked, in case the debug use was after the point of | |
906 | death. */ | |
907 | if (debug.used && !bitmap_empty_p (debug.used)) | |
2abb79fc | 908 | { |
be10bb5a | 909 | df_ref def; |
2abb79fc | 910 | |
be10bb5a | 911 | FOR_EACH_INSN_DEF (def, insn) |
912 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
6baa953c | 913 | marked_insn_p (insn) |
914 | && !control_flow_insn_p (insn) | |
915 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
916 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
2abb79fc | 917 | } |
918 | ||
bf1f8fbc | 919 | if (dump_file) |
920 | { | |
48e1416a | 921 | fprintf (dump_file, "finished processing insn %d live out = ", |
bf1f8fbc | 922 | INSN_UID (insn)); |
0e8e9be3 | 923 | df_print_word_regset (dump_file, local_live); |
bf1f8fbc | 924 | } |
925 | } | |
48e1416a | 926 | |
0e8e9be3 | 927 | block_changed = !bitmap_equal_p (local_live, DF_WORD_LR_IN (bb)); |
bf1f8fbc | 928 | if (block_changed) |
0e8e9be3 | 929 | bitmap_copy (DF_WORD_LR_IN (bb), local_live); |
930 | ||
dcd028e1 | 931 | dead_debug_local_finish (&debug, NULL); |
bf1f8fbc | 932 | BITMAP_FREE (local_live); |
933 | return block_changed; | |
934 | } | |
935 | ||
936 | ||
937 | /* Process basic block BB. Return true if the live_in set has | |
938 | changed. REDO_OUT is true if the info at the bottom of the block | |
939 | needs to be recalculated before starting. AU is the proper set of | |
dcd028e1 | 940 | artificial uses. Track global substitution of uses of dead pseudos |
941 | in debug insns using GLOBAL_DEBUG. */ | |
bf1f8fbc | 942 | |
943 | static bool | |
dcd028e1 | 944 | dce_process_block (basic_block bb, bool redo_out, bitmap au, |
945 | struct dead_debug_global *global_debug) | |
bf1f8fbc | 946 | { |
947 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
57b7551c | 948 | rtx_insn *insn; |
bf1f8fbc | 949 | bool block_changed; |
be10bb5a | 950 | df_ref def; |
dcd028e1 | 951 | struct dead_debug_local debug; |
3072d30e | 952 | |
bf1f8fbc | 953 | if (redo_out) |
3072d30e | 954 | { |
bf1f8fbc | 955 | /* Need to redo the live_out set of this block if when one of |
956 | the succs of this block has had a change in it live in | |
957 | set. */ | |
958 | edge e; | |
959 | edge_iterator ei; | |
960 | df_confluence_function_n con_fun_n = df_lr->problem->con_fun_n; | |
961 | bitmap_clear (DF_LR_OUT (bb)); | |
962 | FOR_EACH_EDGE (e, ei, bb->succs) | |
963 | (*con_fun_n) (e); | |
3072d30e | 964 | } |
965 | ||
bf1f8fbc | 966 | if (dump_file) |
3072d30e | 967 | { |
7e009ff5 | 968 | fprintf (dump_file, "processing block %d lr out = ", bb->index); |
bf1f8fbc | 969 | df_print_regset (dump_file, DF_LR_OUT (bb)); |
3072d30e | 970 | } |
971 | ||
bf1f8fbc | 972 | bitmap_copy (local_live, DF_LR_OUT (bb)); |
973 | ||
a1b0a968 | 974 | df_simulate_initialize_backwards (bb, local_live); |
dcd028e1 | 975 | dead_debug_local_init (&debug, NULL, global_debug); |
011634f2 | 976 | |
3072d30e | 977 | FOR_BB_INSNS_REVERSE (bb, insn) |
2abb79fc | 978 | if (DEBUG_INSN_P (insn)) |
979 | { | |
be10bb5a | 980 | df_ref use; |
981 | FOR_EACH_INSN_USE (use, insn) | |
982 | if (!bitmap_bit_p (local_live, DF_REF_REGNO (use)) | |
983 | && !bitmap_bit_p (au, DF_REF_REGNO (use))) | |
984 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
2abb79fc | 985 | } |
986 | else if (INSN_P (insn)) | |
3072d30e | 987 | { |
cbc39d5b | 988 | bool needed = marked_insn_p (insn); |
ebc94641 | 989 | |
990 | /* The insn is needed if there is someone who uses the output. */ | |
cbc39d5b | 991 | if (!needed) |
be10bb5a | 992 | FOR_EACH_INSN_DEF (def, insn) |
993 | if (bitmap_bit_p (local_live, DF_REF_REGNO (def)) | |
994 | || bitmap_bit_p (au, DF_REF_REGNO (def))) | |
5ea3fd4b | 995 | { |
996 | needed = true; | |
997 | mark_insn (insn, true); | |
998 | break; | |
999 | } | |
48e1416a | 1000 | |
3072d30e | 1001 | /* No matter if the instruction is needed or not, we remove |
1002 | any regno in the defs from the live set. */ | |
1003 | df_simulate_defs (insn, local_live); | |
1004 | ||
1005 | /* On the other hand, we do not allow the dead uses to set | |
1006 | anything in local_live. */ | |
cbc39d5b | 1007 | if (needed) |
3072d30e | 1008 | df_simulate_uses (insn, local_live); |
704e91bd | 1009 | |
5ea3fd4b | 1010 | /* Insert debug temps for dead REGs used in subsequent debug |
704e91bd | 1011 | insns. We may have to emit a debug temp even if the insn |
1012 | was marked, in case the debug use was after the point of | |
1013 | death. */ | |
1014 | if (debug.used && !bitmap_empty_p (debug.used)) | |
be10bb5a | 1015 | FOR_EACH_INSN_DEF (def, insn) |
1016 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
6baa953c | 1017 | needed && !control_flow_insn_p (insn) |
1018 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
1019 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
3072d30e | 1020 | } |
48e1416a | 1021 | |
dcd028e1 | 1022 | dead_debug_local_finish (&debug, NULL); |
a1b0a968 | 1023 | df_simulate_finalize_backwards (bb, local_live); |
3072d30e | 1024 | |
1025 | block_changed = !bitmap_equal_p (local_live, DF_LR_IN (bb)); | |
1026 | if (block_changed) | |
1027 | bitmap_copy (DF_LR_IN (bb), local_live); | |
1028 | ||
1029 | BITMAP_FREE (local_live); | |
1030 | return block_changed; | |
1031 | } | |
1032 | ||
3c6c0b50 | 1033 | |
0e8e9be3 | 1034 | /* Perform fast DCE once initialization is done. If WORD_LEVEL is |
1035 | true, use the word level dce, otherwise do it at the pseudo | |
bf1f8fbc | 1036 | level. */ |
3c6c0b50 | 1037 | |
3072d30e | 1038 | static void |
0e8e9be3 | 1039 | fast_dce (bool word_level) |
3072d30e | 1040 | { |
1041 | int *postorder = df_get_postorder (DF_BACKWARD); | |
1042 | int n_blocks = df_get_n_blocks (DF_BACKWARD); | |
3072d30e | 1043 | /* The set of blocks that have been seen on this iteration. */ |
1044 | bitmap processed = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1045 | /* The set of blocks that need to have the out vectors reset because | |
1046 | the in of one of their successors has changed. */ | |
1047 | bitmap redo_out = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1048 | bitmap all_blocks = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1049 | bool global_changed = true; | |
bf1f8fbc | 1050 | |
1051 | /* These regs are considered always live so if they end up dying | |
1052 | because of some def, we need to bring the back again. Calling | |
1053 | df_simulate_fixup_sets has the disadvantage of calling | |
1054 | bb_has_eh_pred once per insn, so we cache the information | |
1055 | here. */ | |
4b5a4301 | 1056 | bitmap au = &df->regular_block_artificial_uses; |
1057 | bitmap au_eh = &df->eh_block_artificial_uses; | |
ebc94641 | 1058 | int i; |
dcd028e1 | 1059 | struct dead_debug_global global_debug; |
3072d30e | 1060 | |
1061 | prescan_insns_for_dce (true); | |
1062 | ||
1063 | for (i = 0; i < n_blocks; i++) | |
1064 | bitmap_set_bit (all_blocks, postorder[i]); | |
1065 | ||
dcd028e1 | 1066 | dead_debug_global_init (&global_debug, NULL); |
1067 | ||
3072d30e | 1068 | while (global_changed) |
1069 | { | |
1070 | global_changed = false; | |
ebc94641 | 1071 | |
3072d30e | 1072 | for (i = 0; i < n_blocks; i++) |
1073 | { | |
1074 | int index = postorder[i]; | |
f5a6b05f | 1075 | basic_block bb = BASIC_BLOCK_FOR_FN (cfun, index); |
3072d30e | 1076 | bool local_changed; |
1077 | ||
1078 | if (index < NUM_FIXED_BLOCKS) | |
1079 | { | |
1080 | bitmap_set_bit (processed, index); | |
1081 | continue; | |
1082 | } | |
1083 | ||
0e8e9be3 | 1084 | if (word_level) |
48e1416a | 1085 | local_changed |
dcd028e1 | 1086 | = word_dce_process_block (bb, bitmap_bit_p (redo_out, index), |
1087 | &global_debug); | |
bf1f8fbc | 1088 | else |
48e1416a | 1089 | local_changed |
bf1f8fbc | 1090 | = dce_process_block (bb, bitmap_bit_p (redo_out, index), |
dcd028e1 | 1091 | bb_has_eh_pred (bb) ? au_eh : au, |
1092 | &global_debug); | |
3072d30e | 1093 | bitmap_set_bit (processed, index); |
48e1416a | 1094 | |
3072d30e | 1095 | if (local_changed) |
1096 | { | |
1097 | edge e; | |
1098 | edge_iterator ei; | |
1099 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1100 | if (bitmap_bit_p (processed, e->src->index)) | |
1101 | /* Be tricky about when we need to iterate the | |
1102 | analysis. We only have redo the analysis if the | |
1103 | bitmaps change at the top of a block that is the | |
1104 | entry to a loop. */ | |
1105 | global_changed = true; | |
1106 | else | |
1107 | bitmap_set_bit (redo_out, e->src->index); | |
1108 | } | |
1109 | } | |
48e1416a | 1110 | |
3072d30e | 1111 | if (global_changed) |
1112 | { | |
1113 | /* Turn off the RUN_DCE flag to prevent recursive calls to | |
1114 | dce. */ | |
1115 | int old_flag = df_clear_flags (DF_LR_RUN_DCE); | |
1116 | ||
1117 | /* So something was deleted that requires a redo. Do it on | |
1118 | the cheap. */ | |
1119 | delete_unmarked_insns (); | |
53c5d9d4 | 1120 | bitmap_clear (marked); |
3072d30e | 1121 | bitmap_clear (processed); |
1122 | bitmap_clear (redo_out); | |
48e1416a | 1123 | |
3072d30e | 1124 | /* We do not need to rescan any instructions. We only need |
1125 | to redo the dataflow equations for the blocks that had a | |
1126 | change at the top of the block. Then we need to redo the | |
48e1416a | 1127 | iteration. */ |
0e8e9be3 | 1128 | if (word_level) |
1129 | df_analyze_problem (df_word_lr, all_blocks, postorder, n_blocks); | |
bf1f8fbc | 1130 | else |
1131 | df_analyze_problem (df_lr, all_blocks, postorder, n_blocks); | |
3072d30e | 1132 | |
1133 | if (old_flag & DF_LR_RUN_DCE) | |
1134 | df_set_flags (DF_LR_RUN_DCE); | |
ebc94641 | 1135 | |
3072d30e | 1136 | prescan_insns_for_dce (true); |
1137 | } | |
3072d30e | 1138 | } |
1139 | ||
dcd028e1 | 1140 | dead_debug_global_finish (&global_debug, NULL); |
1141 | ||
3072d30e | 1142 | delete_unmarked_insns (); |
1143 | ||
1144 | BITMAP_FREE (processed); | |
1145 | BITMAP_FREE (redo_out); | |
1146 | BITMAP_FREE (all_blocks); | |
1147 | } | |
1148 | ||
1149 | ||
bf1f8fbc | 1150 | /* Fast register level DCE. */ |
3072d30e | 1151 | |
1152 | static unsigned int | |
1153 | rest_of_handle_fast_dce (void) | |
1154 | { | |
1155 | init_dce (true); | |
bf1f8fbc | 1156 | fast_dce (false); |
1157 | fini_dce (true); | |
1158 | return 0; | |
1159 | } | |
1160 | ||
1161 | ||
1162 | /* Fast byte level DCE. */ | |
1163 | ||
0e8e9be3 | 1164 | void |
1165 | run_word_dce (void) | |
bf1f8fbc | 1166 | { |
55fed53b | 1167 | int old_flags; |
1168 | ||
1169 | if (!flag_dce) | |
1170 | return; | |
1171 | ||
0e8e9be3 | 1172 | timevar_push (TV_DCE); |
55fed53b | 1173 | old_flags = df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
0e8e9be3 | 1174 | df_word_lr_add_problem (); |
bf1f8fbc | 1175 | init_dce (true); |
1176 | fast_dce (true); | |
3c6c0b50 | 1177 | fini_dce (true); |
55fed53b | 1178 | df_set_flags (old_flags); |
0e8e9be3 | 1179 | timevar_pop (TV_DCE); |
3072d30e | 1180 | } |
1181 | ||
1182 | ||
1183 | /* This is an internal call that is used by the df live register | |
1184 | problem to run fast dce as a side effect of creating the live | |
1185 | information. The stack is organized so that the lr problem is run, | |
1186 | this pass is run, which updates the live info and the df scanning | |
1187 | info, and then returns to allow the rest of the problems to be run. | |
1188 | ||
1189 | This can be called by elsewhere but it will not update the bit | |
3c6c0b50 | 1190 | vectors for any other problems than LR. */ |
3072d30e | 1191 | |
1192 | void | |
1193 | run_fast_df_dce (void) | |
1194 | { | |
1195 | if (flag_dce) | |
1196 | { | |
1197 | /* If dce is able to delete something, it has to happen | |
1198 | immediately. Otherwise there will be problems handling the | |
1199 | eq_notes. */ | |
bc620c5c | 1200 | int old_flags = |
1201 | df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); | |
1202 | ||
3072d30e | 1203 | df_in_progress = true; |
1204 | rest_of_handle_fast_dce (); | |
3c6c0b50 | 1205 | df_in_progress = false; |
1206 | ||
3072d30e | 1207 | df_set_flags (old_flags); |
1208 | } | |
1209 | } | |
1210 | ||
3c6c0b50 | 1211 | |
ebc94641 | 1212 | /* Run a fast DCE pass. */ |
1213 | ||
1214 | void | |
1215 | run_fast_dce (void) | |
3072d30e | 1216 | { |
ebc94641 | 1217 | if (flag_dce) |
1218 | rest_of_handle_fast_dce (); | |
3072d30e | 1219 | } |
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 */ | |
cbe8bda8 | 1229 | TV_DCE, /* tv_id */ |
1230 | 0, /* properties_required */ | |
1231 | 0, /* properties_provided */ | |
1232 | 0, /* properties_destroyed */ | |
1233 | 0, /* todo_flags_start */ | |
8b88439e | 1234 | TODO_df_finish, /* todo_flags_finish */ |
3072d30e | 1235 | }; |
cbe8bda8 | 1236 | |
1237 | class pass_fast_rtl_dce : public rtl_opt_pass | |
1238 | { | |
1239 | public: | |
9af5ce0c | 1240 | pass_fast_rtl_dce (gcc::context *ctxt) |
1241 | : rtl_opt_pass (pass_data_fast_rtl_dce, ctxt) | |
cbe8bda8 | 1242 | {} |
1243 | ||
1244 | /* opt_pass methods: */ | |
31315c24 | 1245 | virtual bool gate (function *) |
1246 | { | |
1247 | return optimize > 0 && flag_dce && dbg_cnt (dce_fast); | |
1248 | } | |
1249 | ||
65b0537f | 1250 | virtual unsigned int execute (function *) |
1251 | { | |
1252 | return rest_of_handle_fast_dce (); | |
1253 | } | |
cbe8bda8 | 1254 | |
1255 | }; // class pass_fast_rtl_dce | |
1256 | ||
1257 | } // anon namespace | |
1258 | ||
1259 | rtl_opt_pass * | |
1260 | make_pass_fast_rtl_dce (gcc::context *ctxt) | |
1261 | { | |
1262 | return new pass_fast_rtl_dce (ctxt); | |
1263 | } |