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6fb5fa3c | 1 | /* RTL dead code elimination. |
5624e564 | 2 | Copyright (C) 2005-2015 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" | |
c7131fb2 | 23 | #include "backend.h" |
6fb5fa3c | 24 | #include "rtl.h" |
957060b5 AM |
25 | #include "tree.h" |
26 | #include "predict.h" | |
c7131fb2 | 27 | #include "df.h" |
957060b5 | 28 | #include "tm_p.h" |
6fb5fa3c | 29 | #include "regs.h" |
957060b5 AM |
30 | #include "emit-rtl.h" /* FIXME: Can go away once crtl is moved to rtl.h. */ |
31 | #include "alias.h" | |
6fb5fa3c | 32 | #include "flags.h" |
35debead | 33 | #include "except.h" |
60393bbc AM |
34 | #include "cfgrtl.h" |
35 | #include "cfgbuild.h" | |
36 | #include "cfgcleanup.h" | |
6fb5fa3c DB |
37 | #include "cselib.h" |
38 | #include "dce.h" | |
08df6c0d | 39 | #include "valtrack.h" |
6fb5fa3c DB |
40 | #include "tree-pass.h" |
41 | #include "dbgcnt.h" | |
42 | ||
6fb5fa3c DB |
43 | |
44 | /* ------------------------------------------------------------------------- | |
45 | Core mark/delete routines | |
46 | ------------------------------------------------------------------------- */ | |
47 | ||
2e6be65e EB |
48 | /* True if we are invoked while the df engine is running; in this case, |
49 | we don't want to reenter it. */ | |
6fb5fa3c DB |
50 | static bool df_in_progress = false; |
51 | ||
2da02156 EB |
52 | /* True if we are allowed to alter the CFG in this pass. */ |
53 | static bool can_alter_cfg = false; | |
54 | ||
6fb5fa3c DB |
55 | /* Instructions that have been marked but whose dependencies have not |
56 | yet been processed. */ | |
0ece9321 | 57 | static vec<rtx_insn *> worklist; |
6fb5fa3c | 58 | |
2e6be65e EB |
59 | /* Bitmap of instructions marked as needed indexed by INSN_UID. */ |
60 | static sbitmap marked; | |
61 | ||
62 | /* Bitmap obstacks used for block processing by the fast algorithm. */ | |
6fb5fa3c DB |
63 | static bitmap_obstack dce_blocks_bitmap_obstack; |
64 | static bitmap_obstack dce_tmp_bitmap_obstack; | |
65 | ||
0ece9321 | 66 | static bool find_call_stack_args (rtx_call_insn *, bool, bool, bitmap); |
6fb5fa3c | 67 | |
d4d7f1d1 RS |
68 | /* A subroutine for which BODY is part of the instruction being tested; |
69 | either the top-level pattern, or an element of a PARALLEL. The | |
70 | instruction is known not to be a bare USE or CLOBBER. */ | |
6fb5fa3c DB |
71 | |
72 | static bool | |
d4d7f1d1 | 73 | deletable_insn_p_1 (rtx body) |
6fb5fa3c | 74 | { |
6cad9859 | 75 | switch (GET_CODE (body)) |
6fb5fa3c | 76 | { |
6fb5fa3c DB |
77 | case PREFETCH: |
78 | case TRAP_IF: | |
79 | /* The UNSPEC case was added here because the ia-64 claims that | |
80 | USEs do not work after reload and generates UNSPECS rather | |
81 | than USEs. Since dce is run after reload we need to avoid | |
82 | deleting these even if they are dead. If it turns out that | |
83 | USEs really do work after reload, the ia-64 should be | |
84 | changed, and the UNSPEC case can be removed. */ | |
85 | case UNSPEC: | |
86 | return false; | |
87 | ||
d4d7f1d1 | 88 | default: |
1d65f45c | 89 | return !volatile_refs_p (body); |
d4d7f1d1 RS |
90 | } |
91 | } | |
92 | ||
2e6be65e | 93 | |
d4d7f1d1 RS |
94 | /* Return true if INSN is a normal instruction that can be deleted by |
95 | the DCE pass. */ | |
96 | ||
97 | static bool | |
0ece9321 | 98 | deletable_insn_p (rtx_insn *insn, bool fast, bitmap arg_stores) |
d4d7f1d1 RS |
99 | { |
100 | rtx body, x; | |
101 | int i; | |
bfac633a | 102 | df_ref def; |
d4d7f1d1 | 103 | |
5ba5ab9b KZ |
104 | if (CALL_P (insn) |
105 | /* We cannot delete calls inside of the recursive dce because | |
106 | this may cause basic blocks to be deleted and this messes up | |
107 | the rest of the stack of optimization passes. */ | |
108 | && (!df_in_progress) | |
109 | /* We cannot delete pure or const sibling calls because it is | |
110 | hard to see the result. */ | |
becfd6e5 | 111 | && (!SIBLING_CALL_P (insn)) |
5ba5ab9b KZ |
112 | /* We can delete dead const or pure calls as long as they do not |
113 | infinite loop. */ | |
becfd6e5 KZ |
114 | && (RTL_CONST_OR_PURE_CALL_P (insn) |
115 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
0ece9321 DM |
116 | return find_call_stack_args (as_a <rtx_call_insn *> (insn), false, |
117 | fast, arg_stores); | |
becfd6e5 | 118 | |
642d55de EB |
119 | /* Don't delete jumps, notes and the like. */ |
120 | if (!NONJUMP_INSN_P (insn)) | |
121 | return false; | |
122 | ||
2da02156 EB |
123 | /* Don't delete insns that may throw if we cannot do so. */ |
124 | if (!(cfun->can_delete_dead_exceptions && can_alter_cfg) | |
125 | && !insn_nothrow_p (insn)) | |
642d55de EB |
126 | return false; |
127 | ||
211d71a7 | 128 | /* If INSN sets a global_reg, leave it untouched. */ |
bfac633a RS |
129 | FOR_EACH_INSN_DEF (def, insn) |
130 | if (HARD_REGISTER_NUM_P (DF_REF_REGNO (def)) | |
131 | && global_regs[DF_REF_REGNO (def)]) | |
211d71a7 | 132 | return false; |
56873e13 ES |
133 | /* Initialization of pseudo PIC register should never be removed. */ |
134 | else if (DF_REF_REG (def) == pic_offset_table_rtx | |
135 | && REGNO (pic_offset_table_rtx) >= FIRST_PSEUDO_REGISTER) | |
136 | return false; | |
211d71a7 | 137 | |
d4d7f1d1 RS |
138 | body = PATTERN (insn); |
139 | switch (GET_CODE (body)) | |
140 | { | |
141 | case USE: | |
b5b8b0ac | 142 | case VAR_LOCATION: |
d4d7f1d1 RS |
143 | return false; |
144 | ||
6fb5fa3c DB |
145 | case CLOBBER: |
146 | if (fast) | |
147 | { | |
148 | /* A CLOBBER of a dead pseudo register serves no purpose. | |
149 | That is not necessarily true for hard registers until | |
150 | after reload. */ | |
6cad9859 | 151 | x = XEXP (body, 0); |
6fb5fa3c DB |
152 | return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed); |
153 | } | |
d4d7f1d1 | 154 | else |
6fb5fa3c DB |
155 | /* Because of the way that use-def chains are built, it is not |
156 | possible to tell if the clobber is dead because it can | |
157 | never be the target of a use-def chain. */ | |
158 | return false; | |
159 | ||
6cad9859 | 160 | case PARALLEL: |
d4d7f1d1 RS |
161 | for (i = XVECLEN (body, 0) - 1; i >= 0; i--) |
162 | if (!deletable_insn_p_1 (XVECEXP (body, 0, i))) | |
163 | return false; | |
164 | return true; | |
6cad9859 | 165 | |
6fb5fa3c | 166 | default: |
d4d7f1d1 | 167 | return deletable_insn_p_1 (body); |
6fb5fa3c DB |
168 | } |
169 | } | |
170 | ||
171 | ||
2e6be65e | 172 | /* Return true if INSN has been marked as needed. */ |
6fb5fa3c DB |
173 | |
174 | static inline int | |
0ece9321 | 175 | marked_insn_p (rtx_insn *insn) |
6fb5fa3c | 176 | { |
50e94c7e SB |
177 | /* Artificial defs are always needed and they do not have an insn. |
178 | We should never see them here. */ | |
179 | gcc_assert (insn); | |
d7c028c0 | 180 | return bitmap_bit_p (marked, INSN_UID (insn)); |
6fb5fa3c DB |
181 | } |
182 | ||
183 | ||
184 | /* If INSN has not yet been marked as needed, mark it now, and add it to | |
185 | the worklist. */ | |
186 | ||
187 | static void | |
0ece9321 | 188 | mark_insn (rtx_insn *insn, bool fast) |
6fb5fa3c DB |
189 | { |
190 | if (!marked_insn_p (insn)) | |
191 | { | |
192 | if (!fast) | |
9771b263 | 193 | worklist.safe_push (insn); |
d7c028c0 | 194 | bitmap_set_bit (marked, INSN_UID (insn)); |
6fb5fa3c DB |
195 | if (dump_file) |
196 | fprintf (dump_file, " Adding insn %d to worklist\n", INSN_UID (insn)); | |
0196c95e JJ |
197 | if (CALL_P (insn) |
198 | && !df_in_progress | |
199 | && !SIBLING_CALL_P (insn) | |
200 | && (RTL_CONST_OR_PURE_CALL_P (insn) | |
201 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
0ece9321 | 202 | find_call_stack_args (as_a <rtx_call_insn *> (insn), true, fast, NULL); |
6fb5fa3c DB |
203 | } |
204 | } | |
205 | ||
206 | ||
207 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
208 | instruction containing DEST. */ | |
209 | ||
210 | static void | |
7bc980e1 | 211 | mark_nonreg_stores_1 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
212 | { |
213 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
0ece9321 | 214 | mark_insn ((rtx_insn *) data, true); |
6fb5fa3c DB |
215 | } |
216 | ||
217 | ||
218 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
219 | instruction containing DEST. */ | |
220 | ||
221 | static void | |
7bc980e1 | 222 | mark_nonreg_stores_2 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
223 | { |
224 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
0ece9321 | 225 | mark_insn ((rtx_insn *) data, false); |
6fb5fa3c DB |
226 | } |
227 | ||
228 | ||
229 | /* Mark INSN if BODY stores to a non-register destination. */ | |
230 | ||
231 | static void | |
0ece9321 | 232 | mark_nonreg_stores (rtx body, rtx_insn *insn, bool fast) |
6fb5fa3c DB |
233 | { |
234 | if (fast) | |
235 | note_stores (body, mark_nonreg_stores_1, insn); | |
236 | else | |
237 | note_stores (body, mark_nonreg_stores_2, insn); | |
238 | } | |
239 | ||
240 | ||
2e0642cd JJ |
241 | /* Return true if store to MEM, starting OFF bytes from stack pointer, |
242 | is a call argument store, and clear corresponding bits from SP_BYTES | |
243 | bitmap if it is. */ | |
244 | ||
245 | static bool | |
246 | check_argument_store (rtx mem, HOST_WIDE_INT off, HOST_WIDE_INT min_sp_off, | |
247 | HOST_WIDE_INT max_sp_off, bitmap sp_bytes) | |
248 | { | |
249 | HOST_WIDE_INT byte; | |
250 | for (byte = off; byte < off + GET_MODE_SIZE (GET_MODE (mem)); byte++) | |
251 | { | |
252 | if (byte < min_sp_off | |
253 | || byte >= max_sp_off | |
254 | || !bitmap_clear_bit (sp_bytes, byte - min_sp_off)) | |
255 | return false; | |
256 | } | |
257 | return true; | |
258 | } | |
259 | ||
260 | ||
0196c95e JJ |
261 | /* Try to find all stack stores of CALL_INSN arguments if |
262 | ACCUMULATE_OUTGOING_ARGS. If all stack stores have been found | |
263 | and it is therefore safe to eliminate the call, return true, | |
264 | otherwise return false. This function should be first called | |
265 | with DO_MARK false, and only when the CALL_INSN is actually | |
266 | going to be marked called again with DO_MARK true. */ | |
267 | ||
268 | static bool | |
0ece9321 | 269 | find_call_stack_args (rtx_call_insn *call_insn, bool do_mark, bool fast, |
0196c95e JJ |
270 | bitmap arg_stores) |
271 | { | |
0ece9321 DM |
272 | rtx p; |
273 | rtx_insn *insn, *prev_insn; | |
0196c95e JJ |
274 | bool ret; |
275 | HOST_WIDE_INT min_sp_off, max_sp_off; | |
276 | bitmap sp_bytes; | |
277 | ||
278 | gcc_assert (CALL_P (call_insn)); | |
279 | if (!ACCUMULATE_OUTGOING_ARGS) | |
280 | return true; | |
281 | ||
282 | if (!do_mark) | |
283 | { | |
284 | gcc_assert (arg_stores); | |
285 | bitmap_clear (arg_stores); | |
286 | } | |
287 | ||
288 | min_sp_off = INTTYPE_MAXIMUM (HOST_WIDE_INT); | |
289 | max_sp_off = 0; | |
290 | ||
291 | /* First determine the minimum and maximum offset from sp for | |
292 | stored arguments. */ | |
293 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
294 | if (GET_CODE (XEXP (p, 0)) == USE | |
295 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
296 | { | |
f5541398 RS |
297 | rtx mem = XEXP (XEXP (p, 0), 0), addr; |
298 | HOST_WIDE_INT off = 0, size; | |
299 | if (!MEM_SIZE_KNOWN_P (mem)) | |
0196c95e | 300 | return false; |
f5541398 | 301 | size = MEM_SIZE (mem); |
0196c95e JJ |
302 | addr = XEXP (mem, 0); |
303 | if (GET_CODE (addr) == PLUS | |
304 | && REG_P (XEXP (addr, 0)) | |
305 | && CONST_INT_P (XEXP (addr, 1))) | |
306 | { | |
307 | off = INTVAL (XEXP (addr, 1)); | |
308 | addr = XEXP (addr, 0); | |
309 | } | |
310 | if (addr != stack_pointer_rtx) | |
311 | { | |
312 | if (!REG_P (addr)) | |
313 | return false; | |
314 | /* If not fast, use chains to see if addr wasn't set to | |
315 | sp + offset. */ | |
316 | if (!fast) | |
317 | { | |
bfac633a | 318 | df_ref use; |
0196c95e JJ |
319 | struct df_link *defs; |
320 | rtx set; | |
321 | ||
bfac633a RS |
322 | FOR_EACH_INSN_USE (use, call_insn) |
323 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
324 | break; |
325 | ||
bfac633a | 326 | if (use == NULL) |
0196c95e JJ |
327 | return false; |
328 | ||
bfac633a | 329 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
330 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
331 | break; | |
332 | ||
333 | if (defs == NULL) | |
334 | return false; | |
335 | ||
336 | set = single_set (DF_REF_INSN (defs->ref)); | |
337 | if (!set) | |
338 | return false; | |
339 | ||
340 | if (GET_CODE (SET_SRC (set)) != PLUS | |
341 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
342 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
343 | return false; | |
344 | ||
345 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
346 | } | |
347 | else | |
348 | return false; | |
349 | } | |
350 | min_sp_off = MIN (min_sp_off, off); | |
f5541398 | 351 | max_sp_off = MAX (max_sp_off, off + size); |
0196c95e JJ |
352 | } |
353 | ||
354 | if (min_sp_off >= max_sp_off) | |
355 | return true; | |
356 | sp_bytes = BITMAP_ALLOC (NULL); | |
357 | ||
358 | /* Set bits in SP_BYTES bitmap for bytes relative to sp + min_sp_off | |
359 | which contain arguments. Checking has been done in the previous | |
360 | loop. */ | |
361 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
362 | if (GET_CODE (XEXP (p, 0)) == USE | |
363 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
364 | { | |
365 | rtx mem = XEXP (XEXP (p, 0), 0), addr; | |
366 | HOST_WIDE_INT off = 0, byte; | |
367 | addr = XEXP (mem, 0); | |
368 | if (GET_CODE (addr) == PLUS | |
369 | && REG_P (XEXP (addr, 0)) | |
370 | && CONST_INT_P (XEXP (addr, 1))) | |
371 | { | |
372 | off = INTVAL (XEXP (addr, 1)); | |
373 | addr = XEXP (addr, 0); | |
374 | } | |
375 | if (addr != stack_pointer_rtx) | |
376 | { | |
bfac633a | 377 | df_ref use; |
0196c95e JJ |
378 | struct df_link *defs; |
379 | rtx set; | |
380 | ||
bfac633a RS |
381 | FOR_EACH_INSN_USE (use, call_insn) |
382 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
383 | break; |
384 | ||
bfac633a | 385 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
386 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
387 | break; | |
388 | ||
389 | set = single_set (DF_REF_INSN (defs->ref)); | |
390 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
391 | } | |
f5541398 | 392 | for (byte = off; byte < off + MEM_SIZE (mem); byte++) |
0196c95e | 393 | { |
821bb7f8 RG |
394 | if (!bitmap_set_bit (sp_bytes, byte - min_sp_off)) |
395 | gcc_unreachable (); | |
0196c95e JJ |
396 | } |
397 | } | |
398 | ||
399 | /* Walk backwards, looking for argument stores. The search stops | |
750900db | 400 | when seeing another call, sp adjustment or memory store other than |
0196c95e JJ |
401 | argument store. */ |
402 | ret = false; | |
403 | for (insn = PREV_INSN (call_insn); insn; insn = prev_insn) | |
404 | { | |
405 | rtx set, mem, addr; | |
2e0642cd | 406 | HOST_WIDE_INT off; |
0196c95e JJ |
407 | |
408 | if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn))) | |
0ece9321 | 409 | prev_insn = NULL; |
0196c95e JJ |
410 | else |
411 | prev_insn = PREV_INSN (insn); | |
412 | ||
413 | if (CALL_P (insn)) | |
414 | break; | |
415 | ||
2e0642cd | 416 | if (!NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
417 | continue; |
418 | ||
419 | set = single_set (insn); | |
420 | if (!set || SET_DEST (set) == stack_pointer_rtx) | |
421 | break; | |
422 | ||
423 | if (!MEM_P (SET_DEST (set))) | |
424 | continue; | |
425 | ||
426 | mem = SET_DEST (set); | |
427 | addr = XEXP (mem, 0); | |
428 | off = 0; | |
429 | if (GET_CODE (addr) == PLUS | |
430 | && REG_P (XEXP (addr, 0)) | |
431 | && CONST_INT_P (XEXP (addr, 1))) | |
432 | { | |
433 | off = INTVAL (XEXP (addr, 1)); | |
434 | addr = XEXP (addr, 0); | |
435 | } | |
436 | if (addr != stack_pointer_rtx) | |
437 | { | |
438 | if (!REG_P (addr)) | |
439 | break; | |
440 | if (!fast) | |
441 | { | |
bfac633a | 442 | df_ref use; |
0196c95e JJ |
443 | struct df_link *defs; |
444 | rtx set; | |
445 | ||
bfac633a RS |
446 | FOR_EACH_INSN_USE (use, insn) |
447 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
448 | break; |
449 | ||
bfac633a | 450 | if (use == NULL) |
0196c95e JJ |
451 | break; |
452 | ||
bfac633a | 453 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
454 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
455 | break; | |
456 | ||
457 | if (defs == NULL) | |
458 | break; | |
459 | ||
460 | set = single_set (DF_REF_INSN (defs->ref)); | |
461 | if (!set) | |
462 | break; | |
463 | ||
464 | if (GET_CODE (SET_SRC (set)) != PLUS | |
465 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
466 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
467 | break; | |
468 | ||
469 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
470 | } | |
471 | else | |
472 | break; | |
473 | } | |
474 | ||
2e0642cd JJ |
475 | if (GET_MODE_SIZE (GET_MODE (mem)) == 0 |
476 | || !check_argument_store (mem, off, min_sp_off, | |
477 | max_sp_off, sp_bytes)) | |
0196c95e JJ |
478 | break; |
479 | ||
0196c95e JJ |
480 | if (!deletable_insn_p (insn, fast, NULL)) |
481 | break; | |
482 | ||
483 | if (do_mark) | |
484 | mark_insn (insn, fast); | |
485 | else | |
486 | bitmap_set_bit (arg_stores, INSN_UID (insn)); | |
487 | ||
488 | if (bitmap_empty_p (sp_bytes)) | |
489 | { | |
490 | ret = true; | |
491 | break; | |
492 | } | |
493 | } | |
494 | ||
495 | BITMAP_FREE (sp_bytes); | |
496 | if (!ret && arg_stores) | |
497 | bitmap_clear (arg_stores); | |
498 | ||
499 | return ret; | |
500 | } | |
501 | ||
502 | ||
885c9b5d EB |
503 | /* Remove all REG_EQUAL and REG_EQUIV notes referring to the registers INSN |
504 | writes to. */ | |
6fb5fa3c DB |
505 | |
506 | static void | |
0ece9321 | 507 | remove_reg_equal_equiv_notes_for_defs (rtx_insn *insn) |
6fb5fa3c | 508 | { |
bfac633a | 509 | df_ref def; |
885c9b5d | 510 | |
bfac633a RS |
511 | FOR_EACH_INSN_DEF (def, insn) |
512 | remove_reg_equal_equiv_notes_for_regno (DF_REF_REGNO (def)); | |
6fb5fa3c DB |
513 | } |
514 | ||
a7a110bb AO |
515 | /* Scan all BBs for debug insns and reset those that reference values |
516 | defined in unmarked insns. */ | |
517 | ||
518 | static void | |
519 | reset_unmarked_insns_debug_uses (void) | |
520 | { | |
521 | basic_block bb; | |
0ece9321 | 522 | rtx_insn *insn, *next; |
a7a110bb | 523 | |
4f42035e | 524 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
a7a110bb AO |
525 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
526 | if (DEBUG_INSN_P (insn)) | |
527 | { | |
bfac633a | 528 | df_ref use; |
a7a110bb | 529 | |
bfac633a | 530 | FOR_EACH_INSN_USE (use, insn) |
a7a110bb | 531 | { |
a7a110bb AO |
532 | struct df_link *defs; |
533 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
534 | { | |
0ece9321 | 535 | rtx_insn *ref_insn; |
a7a110bb AO |
536 | if (DF_REF_IS_ARTIFICIAL (defs->ref)) |
537 | continue; | |
8ced31fe JJ |
538 | ref_insn = DF_REF_INSN (defs->ref); |
539 | if (!marked_insn_p (ref_insn)) | |
a7a110bb AO |
540 | break; |
541 | } | |
542 | if (!defs) | |
543 | continue; | |
544 | /* ??? FIXME could we propagate the values assigned to | |
545 | each of the DEFs? */ | |
546 | INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC (); | |
547 | df_insn_rescan_debug_internal (insn); | |
8ced31fe | 548 | break; |
a7a110bb AO |
549 | } |
550 | } | |
551 | } | |
6fb5fa3c | 552 | |
9ed7b221 | 553 | /* Delete every instruction that hasn't been marked. */ |
6fb5fa3c DB |
554 | |
555 | static void | |
556 | delete_unmarked_insns (void) | |
557 | { | |
558 | basic_block bb; | |
0ece9321 | 559 | rtx_insn *insn, *next; |
5ba5ab9b | 560 | bool must_clean = false; |
6fb5fa3c | 561 | |
4f42035e | 562 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
cd3f1729 | 563 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
a7a110bb | 564 | if (NONDEBUG_INSN_P (insn)) |
6fb5fa3c | 565 | { |
9ed7b221 | 566 | /* Always delete no-op moves. */ |
6fb5fa3c | 567 | if (noop_move_p (insn)) |
9ed7b221 EB |
568 | ; |
569 | ||
9ed7b221 | 570 | /* Otherwise rely only on the DCE algorithm. */ |
6fb5fa3c DB |
571 | else if (marked_insn_p (insn)) |
572 | continue; | |
573 | ||
cd3f1729 KZ |
574 | /* Beware that reaching a dbg counter limit here can result |
575 | in miscompiled file. This occurs when a group of insns | |
576 | must be deleted together, typically because the kept insn | |
577 | depends on the output from the deleted insn. Deleting | |
578 | this insns in reverse order (both at the bb level and | |
579 | when looking at the blocks) minimizes this, but does not | |
580 | eliminate it, since it is possible for the using insn to | |
581 | be top of a block and the producer to be at the bottom of | |
582 | the block. However, in most cases this will only result | |
583 | in an uninitialized use of an insn that is dead anyway. | |
584 | ||
585 | However, there is one rare case that will cause a | |
586 | miscompile: deletion of non-looping pure and constant | |
587 | calls on a machine where ACCUMULATE_OUTGOING_ARGS is true. | |
588 | In this case it is possible to remove the call, but leave | |
589 | the argument pushes to the stack. Because of the changes | |
590 | to the stack pointer, this will almost always lead to a | |
591 | miscompile. */ | |
6fb5fa3c DB |
592 | if (!dbg_cnt (dce)) |
593 | continue; | |
594 | ||
595 | if (dump_file) | |
596 | fprintf (dump_file, "DCE: Deleting insn %d\n", INSN_UID (insn)); | |
597 | ||
885c9b5d | 598 | /* Before we delete the insn we have to remove the REG_EQUAL notes |
9ed7b221 | 599 | for the destination regs in order to avoid dangling notes. */ |
885c9b5d | 600 | remove_reg_equal_equiv_notes_for_defs (insn); |
6fb5fa3c | 601 | |
5ba5ab9b KZ |
602 | /* If a pure or const call is deleted, this may make the cfg |
603 | have unreachable blocks. We rememeber this and call | |
604 | delete_unreachable_blocks at the end. */ | |
605 | if (CALL_P (insn)) | |
606 | must_clean = true; | |
607 | ||
9ed7b221 | 608 | /* Now delete the insn. */ |
6fb5fa3c | 609 | delete_insn_and_edges (insn); |
6fb5fa3c | 610 | } |
5ba5ab9b KZ |
611 | |
612 | /* Deleted a pure or const call. */ | |
613 | if (must_clean) | |
614 | delete_unreachable_blocks (); | |
6fb5fa3c DB |
615 | } |
616 | ||
617 | ||
6fb5fa3c DB |
618 | /* Go through the instructions and mark those whose necessity is not |
619 | dependent on inter-instruction information. Make sure all other | |
620 | instructions are not marked. */ | |
621 | ||
622 | static void | |
623 | prescan_insns_for_dce (bool fast) | |
624 | { | |
625 | basic_block bb; | |
0ece9321 | 626 | rtx_insn *insn, *prev; |
0196c95e JJ |
627 | bitmap arg_stores = NULL; |
628 | ||
6fb5fa3c DB |
629 | if (dump_file) |
630 | fprintf (dump_file, "Finding needed instructions:\n"); | |
0196c95e JJ |
631 | |
632 | if (!df_in_progress && ACCUMULATE_OUTGOING_ARGS) | |
633 | arg_stores = BITMAP_ALLOC (NULL); | |
634 | ||
11cd3bed | 635 | FOR_EACH_BB_FN (bb, cfun) |
0196c95e JJ |
636 | { |
637 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev) | |
a7a110bb | 638 | if (NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
639 | { |
640 | /* Don't mark argument stores now. They will be marked | |
641 | if needed when the associated CALL is marked. */ | |
642 | if (arg_stores && bitmap_bit_p (arg_stores, INSN_UID (insn))) | |
643 | continue; | |
644 | if (deletable_insn_p (insn, fast, arg_stores)) | |
645 | mark_nonreg_stores (PATTERN (insn), insn, fast); | |
646 | else | |
647 | mark_insn (insn, fast); | |
648 | } | |
649 | /* find_call_stack_args only looks at argument stores in the | |
650 | same bb. */ | |
651 | if (arg_stores) | |
652 | bitmap_clear (arg_stores); | |
653 | } | |
654 | ||
655 | if (arg_stores) | |
656 | BITMAP_FREE (arg_stores); | |
6fb5fa3c DB |
657 | |
658 | if (dump_file) | |
659 | fprintf (dump_file, "Finished finding needed instructions:\n"); | |
660 | } | |
661 | ||
662 | ||
663 | /* UD-based DSE routines. */ | |
664 | ||
6ed3da00 | 665 | /* Mark instructions that define artificially-used registers, such as |
6fb5fa3c DB |
666 | the frame pointer and the stack pointer. */ |
667 | ||
668 | static void | |
669 | mark_artificial_uses (void) | |
670 | { | |
671 | basic_block bb; | |
672 | struct df_link *defs; | |
292321a5 | 673 | df_ref use; |
6fb5fa3c | 674 | |
04a90bec | 675 | FOR_ALL_BB_FN (bb, cfun) |
292321a5 RS |
676 | FOR_EACH_ARTIFICIAL_USE (use, bb->index) |
677 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
678 | if (!DF_REF_IS_ARTIFICIAL (defs->ref)) | |
679 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
680 | } |
681 | ||
2e6be65e | 682 | |
6fb5fa3c DB |
683 | /* Mark every instruction that defines a register value that INSN uses. */ |
684 | ||
685 | static void | |
0ece9321 | 686 | mark_reg_dependencies (rtx_insn *insn) |
6fb5fa3c DB |
687 | { |
688 | struct df_link *defs; | |
bfac633a | 689 | df_ref use; |
6fb5fa3c | 690 | |
b5b8b0ac AO |
691 | if (DEBUG_INSN_P (insn)) |
692 | return; | |
693 | ||
bfac633a | 694 | FOR_EACH_INSN_USE (use, insn) |
6fb5fa3c | 695 | { |
6fb5fa3c DB |
696 | if (dump_file) |
697 | { | |
698 | fprintf (dump_file, "Processing use of "); | |
699 | print_simple_rtl (dump_file, DF_REF_REG (use)); | |
700 | fprintf (dump_file, " in insn %d:\n", INSN_UID (insn)); | |
701 | } | |
702 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
50e94c7e SB |
703 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
704 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
705 | } |
706 | } | |
707 | ||
708 | ||
2e6be65e EB |
709 | /* Initialize global variables for a new DCE pass. */ |
710 | ||
6fb5fa3c | 711 | static void |
2e6be65e EB |
712 | init_dce (bool fast) |
713 | { | |
714 | if (!df_in_progress) | |
715 | { | |
716 | if (!fast) | |
7b19209f SB |
717 | { |
718 | df_set_flags (DF_RD_PRUNE_DEAD_DEFS); | |
719 | df_chain_add_problem (DF_UD_CHAIN); | |
720 | } | |
2e6be65e EB |
721 | df_analyze (); |
722 | } | |
723 | ||
724 | if (dump_file) | |
725 | df_dump (dump_file); | |
726 | ||
727 | if (fast) | |
728 | { | |
729 | bitmap_obstack_initialize (&dce_blocks_bitmap_obstack); | |
730 | bitmap_obstack_initialize (&dce_tmp_bitmap_obstack); | |
2da02156 | 731 | can_alter_cfg = false; |
2e6be65e | 732 | } |
2da02156 EB |
733 | else |
734 | can_alter_cfg = true; | |
2e6be65e EB |
735 | |
736 | marked = sbitmap_alloc (get_max_uid () + 1); | |
f61e445a | 737 | bitmap_clear (marked); |
2e6be65e EB |
738 | } |
739 | ||
740 | ||
741 | /* Free the data allocated by init_dce. */ | |
742 | ||
743 | static void | |
744 | fini_dce (bool fast) | |
6fb5fa3c DB |
745 | { |
746 | sbitmap_free (marked); | |
2e6be65e EB |
747 | |
748 | if (fast) | |
749 | { | |
750 | bitmap_obstack_release (&dce_blocks_bitmap_obstack); | |
751 | bitmap_obstack_release (&dce_tmp_bitmap_obstack); | |
752 | } | |
6fb5fa3c DB |
753 | } |
754 | ||
755 | ||
756 | /* UD-chain based DCE. */ | |
757 | ||
758 | static unsigned int | |
759 | rest_of_handle_ud_dce (void) | |
760 | { | |
0ece9321 | 761 | rtx_insn *insn; |
6fb5fa3c | 762 | |
6fb5fa3c DB |
763 | init_dce (false); |
764 | ||
765 | prescan_insns_for_dce (false); | |
766 | mark_artificial_uses (); | |
9771b263 | 767 | while (worklist.length () > 0) |
6fb5fa3c | 768 | { |
9771b263 | 769 | insn = worklist.pop (); |
6fb5fa3c DB |
770 | mark_reg_dependencies (insn); |
771 | } | |
9771b263 | 772 | worklist.release (); |
2e6be65e | 773 | |
a7a110bb AO |
774 | if (MAY_HAVE_DEBUG_INSNS) |
775 | reset_unmarked_insns_debug_uses (); | |
776 | ||
6fb5fa3c DB |
777 | /* Before any insns are deleted, we must remove the chains since |
778 | they are not bidirectional. */ | |
779 | df_remove_problem (df_chain); | |
780 | delete_unmarked_insns (); | |
781 | ||
2e6be65e | 782 | fini_dce (false); |
6fb5fa3c DB |
783 | return 0; |
784 | } | |
785 | ||
786 | ||
17795822 TS |
787 | namespace { |
788 | ||
789 | const pass_data pass_data_ud_rtl_dce = | |
6fb5fa3c | 790 | { |
27a4cd48 DM |
791 | RTL_PASS, /* type */ |
792 | "ud_dce", /* name */ | |
793 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
794 | TV_DCE, /* tv_id */ |
795 | 0, /* properties_required */ | |
796 | 0, /* properties_provided */ | |
797 | 0, /* properties_destroyed */ | |
798 | 0, /* todo_flags_start */ | |
3bea341f | 799 | TODO_df_finish, /* todo_flags_finish */ |
6fb5fa3c DB |
800 | }; |
801 | ||
17795822 | 802 | class pass_ud_rtl_dce : public rtl_opt_pass |
27a4cd48 DM |
803 | { |
804 | public: | |
c3284718 RS |
805 | pass_ud_rtl_dce (gcc::context *ctxt) |
806 | : rtl_opt_pass (pass_data_ud_rtl_dce, ctxt) | |
27a4cd48 DM |
807 | {} |
808 | ||
809 | /* opt_pass methods: */ | |
1a3d085c TS |
810 | virtual bool gate (function *) |
811 | { | |
812 | return optimize > 1 && flag_dce && dbg_cnt (dce_ud); | |
813 | } | |
814 | ||
be55bfe6 TS |
815 | virtual unsigned int execute (function *) |
816 | { | |
817 | return rest_of_handle_ud_dce (); | |
818 | } | |
27a4cd48 DM |
819 | |
820 | }; // class pass_ud_rtl_dce | |
821 | ||
17795822 TS |
822 | } // anon namespace |
823 | ||
27a4cd48 DM |
824 | rtl_opt_pass * |
825 | make_pass_ud_rtl_dce (gcc::context *ctxt) | |
826 | { | |
827 | return new pass_ud_rtl_dce (ctxt); | |
828 | } | |
829 | ||
2e6be65e | 830 | |
6fb5fa3c DB |
831 | /* ------------------------------------------------------------------------- |
832 | Fast DCE functions | |
833 | ------------------------------------------------------------------------- */ | |
834 | ||
cc806ac1 RS |
835 | /* Process basic block BB. Return true if the live_in set has |
836 | changed. REDO_OUT is true if the info at the bottom of the block | |
837 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
838 | artificial uses. Track global substitution of uses of dead pseudos |
839 | in debug insns using GLOBAL_DEBUG. */ | |
6fb5fa3c DB |
840 | |
841 | static bool | |
e9f950ba AO |
842 | word_dce_process_block (basic_block bb, bool redo_out, |
843 | struct dead_debug_global *global_debug) | |
6fb5fa3c DB |
844 | { |
845 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
0ece9321 | 846 | rtx_insn *insn; |
6fb5fa3c | 847 | bool block_changed; |
e9f950ba | 848 | struct dead_debug_local debug; |
6fb5fa3c DB |
849 | |
850 | if (redo_out) | |
851 | { | |
852 | /* Need to redo the live_out set of this block if when one of | |
853 | the succs of this block has had a change in it live in | |
854 | set. */ | |
855 | edge e; | |
856 | edge_iterator ei; | |
8d074192 BS |
857 | df_confluence_function_n con_fun_n = df_word_lr->problem->con_fun_n; |
858 | bitmap_clear (DF_WORD_LR_OUT (bb)); | |
6fb5fa3c DB |
859 | FOR_EACH_EDGE (e, ei, bb->succs) |
860 | (*con_fun_n) (e); | |
861 | } | |
862 | ||
863 | if (dump_file) | |
864 | { | |
865 | fprintf (dump_file, "processing block %d live out = ", bb->index); | |
8d074192 | 866 | df_print_word_regset (dump_file, DF_WORD_LR_OUT (bb)); |
6fb5fa3c DB |
867 | } |
868 | ||
8d074192 | 869 | bitmap_copy (local_live, DF_WORD_LR_OUT (bb)); |
e9f950ba | 870 | dead_debug_local_init (&debug, NULL, global_debug); |
cc806ac1 RS |
871 | |
872 | FOR_BB_INSNS_REVERSE (bb, insn) | |
1adbb361 AO |
873 | if (DEBUG_INSN_P (insn)) |
874 | { | |
bfac633a RS |
875 | df_ref use; |
876 | FOR_EACH_INSN_USE (use, insn) | |
877 | if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER | |
878 | && (GET_MODE_SIZE (GET_MODE (DF_REF_REAL_REG (use))) | |
1adbb361 | 879 | == 2 * UNITS_PER_WORD) |
bfac633a RS |
880 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use)) |
881 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use) + 1)) | |
882 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
1adbb361 AO |
883 | } |
884 | else if (INSN_P (insn)) | |
cc806ac1 | 885 | { |
8d074192 | 886 | bool any_changed; |
1adbb361 | 887 | |
cc806ac1 RS |
888 | /* No matter if the instruction is needed or not, we remove |
889 | any regno in the defs from the live set. */ | |
8d074192 BS |
890 | any_changed = df_word_lr_simulate_defs (insn, local_live); |
891 | if (any_changed) | |
892 | mark_insn (insn, true); | |
cc806ac1 RS |
893 | |
894 | /* On the other hand, we do not allow the dead uses to set | |
895 | anything in local_live. */ | |
896 | if (marked_insn_p (insn)) | |
8d074192 | 897 | df_word_lr_simulate_uses (insn, local_live); |
6f9e260c | 898 | |
39bc0f01 | 899 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
900 | insns. We may have to emit a debug temp even if the insn |
901 | was marked, in case the debug use was after the point of | |
902 | death. */ | |
903 | if (debug.used && !bitmap_empty_p (debug.used)) | |
1adbb361 | 904 | { |
bfac633a | 905 | df_ref def; |
1adbb361 | 906 | |
bfac633a RS |
907 | FOR_EACH_INSN_DEF (def, insn) |
908 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
85d87497 JJ |
909 | marked_insn_p (insn) |
910 | && !control_flow_insn_p (insn) | |
911 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
912 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
1adbb361 AO |
913 | } |
914 | ||
cc806ac1 RS |
915 | if (dump_file) |
916 | { | |
b8698a0f | 917 | fprintf (dump_file, "finished processing insn %d live out = ", |
cc806ac1 | 918 | INSN_UID (insn)); |
8d074192 | 919 | df_print_word_regset (dump_file, local_live); |
cc806ac1 RS |
920 | } |
921 | } | |
b8698a0f | 922 | |
8d074192 | 923 | block_changed = !bitmap_equal_p (local_live, DF_WORD_LR_IN (bb)); |
cc806ac1 | 924 | if (block_changed) |
8d074192 BS |
925 | bitmap_copy (DF_WORD_LR_IN (bb), local_live); |
926 | ||
e9f950ba | 927 | dead_debug_local_finish (&debug, NULL); |
cc806ac1 RS |
928 | BITMAP_FREE (local_live); |
929 | return block_changed; | |
930 | } | |
931 | ||
932 | ||
933 | /* Process basic block BB. Return true if the live_in set has | |
934 | changed. REDO_OUT is true if the info at the bottom of the block | |
935 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
936 | artificial uses. Track global substitution of uses of dead pseudos |
937 | in debug insns using GLOBAL_DEBUG. */ | |
cc806ac1 RS |
938 | |
939 | static bool | |
e9f950ba AO |
940 | dce_process_block (basic_block bb, bool redo_out, bitmap au, |
941 | struct dead_debug_global *global_debug) | |
cc806ac1 RS |
942 | { |
943 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
0ece9321 | 944 | rtx_insn *insn; |
cc806ac1 | 945 | bool block_changed; |
bfac633a | 946 | df_ref def; |
e9f950ba | 947 | struct dead_debug_local debug; |
6fb5fa3c | 948 | |
cc806ac1 | 949 | if (redo_out) |
6fb5fa3c | 950 | { |
cc806ac1 RS |
951 | /* Need to redo the live_out set of this block if when one of |
952 | the succs of this block has had a change in it live in | |
953 | set. */ | |
954 | edge e; | |
955 | edge_iterator ei; | |
956 | df_confluence_function_n con_fun_n = df_lr->problem->con_fun_n; | |
957 | bitmap_clear (DF_LR_OUT (bb)); | |
958 | FOR_EACH_EDGE (e, ei, bb->succs) | |
959 | (*con_fun_n) (e); | |
6fb5fa3c DB |
960 | } |
961 | ||
cc806ac1 | 962 | if (dump_file) |
6fb5fa3c | 963 | { |
fafe34f9 | 964 | fprintf (dump_file, "processing block %d lr out = ", bb->index); |
cc806ac1 | 965 | df_print_regset (dump_file, DF_LR_OUT (bb)); |
6fb5fa3c DB |
966 | } |
967 | ||
cc806ac1 RS |
968 | bitmap_copy (local_live, DF_LR_OUT (bb)); |
969 | ||
02b47899 | 970 | df_simulate_initialize_backwards (bb, local_live); |
e9f950ba | 971 | dead_debug_local_init (&debug, NULL, global_debug); |
541d3103 | 972 | |
6fb5fa3c | 973 | FOR_BB_INSNS_REVERSE (bb, insn) |
1adbb361 AO |
974 | if (DEBUG_INSN_P (insn)) |
975 | { | |
bfac633a RS |
976 | df_ref use; |
977 | FOR_EACH_INSN_USE (use, insn) | |
978 | if (!bitmap_bit_p (local_live, DF_REF_REGNO (use)) | |
979 | && !bitmap_bit_p (au, DF_REF_REGNO (use))) | |
980 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
1adbb361 AO |
981 | } |
982 | else if (INSN_P (insn)) | |
6fb5fa3c | 983 | { |
f251709a | 984 | bool needed = marked_insn_p (insn); |
9ed7b221 EB |
985 | |
986 | /* The insn is needed if there is someone who uses the output. */ | |
f251709a | 987 | if (!needed) |
bfac633a RS |
988 | FOR_EACH_INSN_DEF (def, insn) |
989 | if (bitmap_bit_p (local_live, DF_REF_REGNO (def)) | |
990 | || bitmap_bit_p (au, DF_REF_REGNO (def))) | |
39bc0f01 AO |
991 | { |
992 | needed = true; | |
993 | mark_insn (insn, true); | |
994 | break; | |
995 | } | |
b8698a0f | 996 | |
6fb5fa3c DB |
997 | /* No matter if the instruction is needed or not, we remove |
998 | any regno in the defs from the live set. */ | |
999 | df_simulate_defs (insn, local_live); | |
1000 | ||
1001 | /* On the other hand, we do not allow the dead uses to set | |
1002 | anything in local_live. */ | |
f251709a | 1003 | if (needed) |
6fb5fa3c | 1004 | df_simulate_uses (insn, local_live); |
6f9e260c | 1005 | |
39bc0f01 | 1006 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
1007 | insns. We may have to emit a debug temp even if the insn |
1008 | was marked, in case the debug use was after the point of | |
1009 | death. */ | |
1010 | if (debug.used && !bitmap_empty_p (debug.used)) | |
bfac633a RS |
1011 | FOR_EACH_INSN_DEF (def, insn) |
1012 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
85d87497 JJ |
1013 | needed && !control_flow_insn_p (insn) |
1014 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
1015 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
6fb5fa3c | 1016 | } |
b8698a0f | 1017 | |
e9f950ba | 1018 | dead_debug_local_finish (&debug, NULL); |
02b47899 | 1019 | df_simulate_finalize_backwards (bb, local_live); |
6fb5fa3c DB |
1020 | |
1021 | block_changed = !bitmap_equal_p (local_live, DF_LR_IN (bb)); | |
1022 | if (block_changed) | |
1023 | bitmap_copy (DF_LR_IN (bb), local_live); | |
1024 | ||
1025 | BITMAP_FREE (local_live); | |
1026 | return block_changed; | |
1027 | } | |
1028 | ||
2e6be65e | 1029 | |
8d074192 BS |
1030 | /* Perform fast DCE once initialization is done. If WORD_LEVEL is |
1031 | true, use the word level dce, otherwise do it at the pseudo | |
cc806ac1 | 1032 | level. */ |
2e6be65e | 1033 | |
6fb5fa3c | 1034 | static void |
8d074192 | 1035 | fast_dce (bool word_level) |
6fb5fa3c DB |
1036 | { |
1037 | int *postorder = df_get_postorder (DF_BACKWARD); | |
1038 | int n_blocks = df_get_n_blocks (DF_BACKWARD); | |
6fb5fa3c DB |
1039 | /* The set of blocks that have been seen on this iteration. */ |
1040 | bitmap processed = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1041 | /* The set of blocks that need to have the out vectors reset because | |
1042 | the in of one of their successors has changed. */ | |
1043 | bitmap redo_out = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1044 | bitmap all_blocks = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1045 | bool global_changed = true; | |
cc806ac1 RS |
1046 | |
1047 | /* These regs are considered always live so if they end up dying | |
1048 | because of some def, we need to bring the back again. Calling | |
1049 | df_simulate_fixup_sets has the disadvantage of calling | |
1050 | bb_has_eh_pred once per insn, so we cache the information | |
1051 | here. */ | |
a7e3698d JH |
1052 | bitmap au = &df->regular_block_artificial_uses; |
1053 | bitmap au_eh = &df->eh_block_artificial_uses; | |
9ed7b221 | 1054 | int i; |
e9f950ba | 1055 | struct dead_debug_global global_debug; |
6fb5fa3c DB |
1056 | |
1057 | prescan_insns_for_dce (true); | |
1058 | ||
1059 | for (i = 0; i < n_blocks; i++) | |
1060 | bitmap_set_bit (all_blocks, postorder[i]); | |
1061 | ||
e9f950ba AO |
1062 | dead_debug_global_init (&global_debug, NULL); |
1063 | ||
6fb5fa3c DB |
1064 | while (global_changed) |
1065 | { | |
1066 | global_changed = false; | |
9ed7b221 | 1067 | |
6fb5fa3c DB |
1068 | for (i = 0; i < n_blocks; i++) |
1069 | { | |
1070 | int index = postorder[i]; | |
06e28de2 | 1071 | basic_block bb = BASIC_BLOCK_FOR_FN (cfun, index); |
6fb5fa3c DB |
1072 | bool local_changed; |
1073 | ||
1074 | if (index < NUM_FIXED_BLOCKS) | |
1075 | { | |
1076 | bitmap_set_bit (processed, index); | |
1077 | continue; | |
1078 | } | |
1079 | ||
8d074192 | 1080 | if (word_level) |
b8698a0f | 1081 | local_changed |
e9f950ba AO |
1082 | = word_dce_process_block (bb, bitmap_bit_p (redo_out, index), |
1083 | &global_debug); | |
cc806ac1 | 1084 | else |
b8698a0f | 1085 | local_changed |
cc806ac1 | 1086 | = dce_process_block (bb, bitmap_bit_p (redo_out, index), |
e9f950ba AO |
1087 | bb_has_eh_pred (bb) ? au_eh : au, |
1088 | &global_debug); | |
6fb5fa3c | 1089 | bitmap_set_bit (processed, index); |
b8698a0f | 1090 | |
6fb5fa3c DB |
1091 | if (local_changed) |
1092 | { | |
1093 | edge e; | |
1094 | edge_iterator ei; | |
1095 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1096 | if (bitmap_bit_p (processed, e->src->index)) | |
1097 | /* Be tricky about when we need to iterate the | |
1098 | analysis. We only have redo the analysis if the | |
1099 | bitmaps change at the top of a block that is the | |
1100 | entry to a loop. */ | |
1101 | global_changed = true; | |
1102 | else | |
1103 | bitmap_set_bit (redo_out, e->src->index); | |
1104 | } | |
1105 | } | |
b8698a0f | 1106 | |
6fb5fa3c DB |
1107 | if (global_changed) |
1108 | { | |
1109 | /* Turn off the RUN_DCE flag to prevent recursive calls to | |
1110 | dce. */ | |
1111 | int old_flag = df_clear_flags (DF_LR_RUN_DCE); | |
1112 | ||
1113 | /* So something was deleted that requires a redo. Do it on | |
1114 | the cheap. */ | |
1115 | delete_unmarked_insns (); | |
f61e445a | 1116 | bitmap_clear (marked); |
6fb5fa3c DB |
1117 | bitmap_clear (processed); |
1118 | bitmap_clear (redo_out); | |
b8698a0f | 1119 | |
6fb5fa3c DB |
1120 | /* We do not need to rescan any instructions. We only need |
1121 | to redo the dataflow equations for the blocks that had a | |
1122 | change at the top of the block. Then we need to redo the | |
b8698a0f | 1123 | iteration. */ |
8d074192 BS |
1124 | if (word_level) |
1125 | df_analyze_problem (df_word_lr, all_blocks, postorder, n_blocks); | |
cc806ac1 RS |
1126 | else |
1127 | df_analyze_problem (df_lr, all_blocks, postorder, n_blocks); | |
6fb5fa3c DB |
1128 | |
1129 | if (old_flag & DF_LR_RUN_DCE) | |
1130 | df_set_flags (DF_LR_RUN_DCE); | |
9ed7b221 | 1131 | |
6fb5fa3c DB |
1132 | prescan_insns_for_dce (true); |
1133 | } | |
6fb5fa3c DB |
1134 | } |
1135 | ||
e9f950ba AO |
1136 | dead_debug_global_finish (&global_debug, NULL); |
1137 | ||
6fb5fa3c DB |
1138 | delete_unmarked_insns (); |
1139 | ||
1140 | BITMAP_FREE (processed); | |
1141 | BITMAP_FREE (redo_out); | |
1142 | BITMAP_FREE (all_blocks); | |
1143 | } | |
1144 | ||
1145 | ||
cc806ac1 | 1146 | /* Fast register level DCE. */ |
6fb5fa3c DB |
1147 | |
1148 | static unsigned int | |
1149 | rest_of_handle_fast_dce (void) | |
1150 | { | |
1151 | init_dce (true); | |
cc806ac1 RS |
1152 | fast_dce (false); |
1153 | fini_dce (true); | |
1154 | return 0; | |
1155 | } | |
1156 | ||
1157 | ||
1158 | /* Fast byte level DCE. */ | |
1159 | ||
8d074192 BS |
1160 | void |
1161 | run_word_dce (void) | |
cc806ac1 | 1162 | { |
25aef556 BS |
1163 | int old_flags; |
1164 | ||
1165 | if (!flag_dce) | |
1166 | return; | |
1167 | ||
8d074192 | 1168 | timevar_push (TV_DCE); |
25aef556 | 1169 | old_flags = df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
8d074192 | 1170 | df_word_lr_add_problem (); |
cc806ac1 RS |
1171 | init_dce (true); |
1172 | fast_dce (true); | |
2e6be65e | 1173 | fini_dce (true); |
25aef556 | 1174 | df_set_flags (old_flags); |
8d074192 | 1175 | timevar_pop (TV_DCE); |
6fb5fa3c DB |
1176 | } |
1177 | ||
1178 | ||
1179 | /* This is an internal call that is used by the df live register | |
1180 | problem to run fast dce as a side effect of creating the live | |
1181 | information. The stack is organized so that the lr problem is run, | |
1182 | this pass is run, which updates the live info and the df scanning | |
1183 | info, and then returns to allow the rest of the problems to be run. | |
1184 | ||
1185 | This can be called by elsewhere but it will not update the bit | |
2e6be65e | 1186 | vectors for any other problems than LR. */ |
6fb5fa3c DB |
1187 | |
1188 | void | |
1189 | run_fast_df_dce (void) | |
1190 | { | |
1191 | if (flag_dce) | |
1192 | { | |
1193 | /* If dce is able to delete something, it has to happen | |
1194 | immediately. Otherwise there will be problems handling the | |
1195 | eq_notes. */ | |
81f40b79 ILT |
1196 | int old_flags = |
1197 | df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); | |
1198 | ||
6fb5fa3c DB |
1199 | df_in_progress = true; |
1200 | rest_of_handle_fast_dce (); | |
2e6be65e EB |
1201 | df_in_progress = false; |
1202 | ||
6fb5fa3c DB |
1203 | df_set_flags (old_flags); |
1204 | } | |
1205 | } | |
1206 | ||
2e6be65e | 1207 | |
9ed7b221 EB |
1208 | /* Run a fast DCE pass. */ |
1209 | ||
1210 | void | |
1211 | run_fast_dce (void) | |
6fb5fa3c | 1212 | { |
9ed7b221 EB |
1213 | if (flag_dce) |
1214 | rest_of_handle_fast_dce (); | |
6fb5fa3c DB |
1215 | } |
1216 | ||
1217 | ||
17795822 TS |
1218 | namespace { |
1219 | ||
1220 | const pass_data pass_data_fast_rtl_dce = | |
6fb5fa3c | 1221 | { |
27a4cd48 DM |
1222 | RTL_PASS, /* type */ |
1223 | "rtl_dce", /* name */ | |
1224 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
1225 | TV_DCE, /* tv_id */ |
1226 | 0, /* properties_required */ | |
1227 | 0, /* properties_provided */ | |
1228 | 0, /* properties_destroyed */ | |
1229 | 0, /* todo_flags_start */ | |
3bea341f | 1230 | TODO_df_finish, /* todo_flags_finish */ |
6fb5fa3c | 1231 | }; |
27a4cd48 | 1232 | |
17795822 | 1233 | class pass_fast_rtl_dce : public rtl_opt_pass |
27a4cd48 DM |
1234 | { |
1235 | public: | |
c3284718 RS |
1236 | pass_fast_rtl_dce (gcc::context *ctxt) |
1237 | : rtl_opt_pass (pass_data_fast_rtl_dce, ctxt) | |
27a4cd48 DM |
1238 | {} |
1239 | ||
1240 | /* opt_pass methods: */ | |
1a3d085c TS |
1241 | virtual bool gate (function *) |
1242 | { | |
1243 | return optimize > 0 && flag_dce && dbg_cnt (dce_fast); | |
1244 | } | |
1245 | ||
be55bfe6 TS |
1246 | virtual unsigned int execute (function *) |
1247 | { | |
1248 | return rest_of_handle_fast_dce (); | |
1249 | } | |
27a4cd48 DM |
1250 | |
1251 | }; // class pass_fast_rtl_dce | |
1252 | ||
17795822 TS |
1253 | } // anon namespace |
1254 | ||
27a4cd48 DM |
1255 | rtl_opt_pass * |
1256 | make_pass_fast_rtl_dce (gcc::context *ctxt) | |
1257 | { | |
1258 | return new pass_fast_rtl_dce (ctxt); | |
1259 | } |