]>
Commit | Line | Data |
---|---|---|
6fb5fa3c | 1 | /* RTL dead code elimination. |
85ec4feb | 2 | Copyright (C) 2005-2018 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" |
4d0cdd0c | 28 | #include "memmodel.h" |
957060b5 | 29 | #include "tm_p.h" |
957060b5 | 30 | #include "emit-rtl.h" /* FIXME: Can go away once crtl is moved to rtl.h. */ |
60393bbc AM |
31 | #include "cfgrtl.h" |
32 | #include "cfgbuild.h" | |
33 | #include "cfgcleanup.h" | |
6fb5fa3c | 34 | #include "dce.h" |
08df6c0d | 35 | #include "valtrack.h" |
6fb5fa3c DB |
36 | #include "tree-pass.h" |
37 | #include "dbgcnt.h" | |
38 | ||
6fb5fa3c DB |
39 | |
40 | /* ------------------------------------------------------------------------- | |
41 | Core mark/delete routines | |
42 | ------------------------------------------------------------------------- */ | |
43 | ||
2e6be65e EB |
44 | /* True if we are invoked while the df engine is running; in this case, |
45 | we don't want to reenter it. */ | |
6fb5fa3c DB |
46 | static bool df_in_progress = false; |
47 | ||
2da02156 EB |
48 | /* True if we are allowed to alter the CFG in this pass. */ |
49 | static bool can_alter_cfg = false; | |
50 | ||
6fb5fa3c DB |
51 | /* Instructions that have been marked but whose dependencies have not |
52 | yet been processed. */ | |
0ece9321 | 53 | static vec<rtx_insn *> worklist; |
6fb5fa3c | 54 | |
2e6be65e EB |
55 | /* Bitmap of instructions marked as needed indexed by INSN_UID. */ |
56 | static sbitmap marked; | |
57 | ||
58 | /* Bitmap obstacks used for block processing by the fast algorithm. */ | |
6fb5fa3c DB |
59 | static bitmap_obstack dce_blocks_bitmap_obstack; |
60 | static bitmap_obstack dce_tmp_bitmap_obstack; | |
61 | ||
0ece9321 | 62 | static bool find_call_stack_args (rtx_call_insn *, bool, bool, bitmap); |
6fb5fa3c | 63 | |
d4d7f1d1 RS |
64 | /* A subroutine for which BODY is part of the instruction being tested; |
65 | either the top-level pattern, or an element of a PARALLEL. The | |
66 | instruction is known not to be a bare USE or CLOBBER. */ | |
6fb5fa3c DB |
67 | |
68 | static bool | |
d4d7f1d1 | 69 | deletable_insn_p_1 (rtx body) |
6fb5fa3c | 70 | { |
6cad9859 | 71 | switch (GET_CODE (body)) |
6fb5fa3c | 72 | { |
6fb5fa3c DB |
73 | case PREFETCH: |
74 | case TRAP_IF: | |
75 | /* The UNSPEC case was added here because the ia-64 claims that | |
76 | USEs do not work after reload and generates UNSPECS rather | |
77 | than USEs. Since dce is run after reload we need to avoid | |
78 | deleting these even if they are dead. If it turns out that | |
79 | USEs really do work after reload, the ia-64 should be | |
80 | changed, and the UNSPEC case can be removed. */ | |
81 | case UNSPEC: | |
82 | return false; | |
83 | ||
d4d7f1d1 | 84 | default: |
1d65f45c | 85 | return !volatile_refs_p (body); |
d4d7f1d1 RS |
86 | } |
87 | } | |
88 | ||
2e6be65e | 89 | |
d4d7f1d1 RS |
90 | /* Return true if INSN is a normal instruction that can be deleted by |
91 | the DCE pass. */ | |
92 | ||
93 | static bool | |
0ece9321 | 94 | deletable_insn_p (rtx_insn *insn, bool fast, bitmap arg_stores) |
d4d7f1d1 RS |
95 | { |
96 | rtx body, x; | |
97 | int i; | |
bfac633a | 98 | df_ref def; |
d4d7f1d1 | 99 | |
5ba5ab9b KZ |
100 | if (CALL_P (insn) |
101 | /* We cannot delete calls inside of the recursive dce because | |
102 | this may cause basic blocks to be deleted and this messes up | |
103 | the rest of the stack of optimization passes. */ | |
104 | && (!df_in_progress) | |
105 | /* We cannot delete pure or const sibling calls because it is | |
106 | hard to see the result. */ | |
becfd6e5 | 107 | && (!SIBLING_CALL_P (insn)) |
5ba5ab9b KZ |
108 | /* We can delete dead const or pure calls as long as they do not |
109 | infinite loop. */ | |
becfd6e5 KZ |
110 | && (RTL_CONST_OR_PURE_CALL_P (insn) |
111 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
0ece9321 DM |
112 | return find_call_stack_args (as_a <rtx_call_insn *> (insn), false, |
113 | fast, arg_stores); | |
becfd6e5 | 114 | |
642d55de EB |
115 | /* Don't delete jumps, notes and the like. */ |
116 | if (!NONJUMP_INSN_P (insn)) | |
117 | return false; | |
118 | ||
2da02156 EB |
119 | /* Don't delete insns that may throw if we cannot do so. */ |
120 | if (!(cfun->can_delete_dead_exceptions && can_alter_cfg) | |
121 | && !insn_nothrow_p (insn)) | |
642d55de EB |
122 | return false; |
123 | ||
211d71a7 | 124 | /* If INSN sets a global_reg, leave it untouched. */ |
bfac633a RS |
125 | FOR_EACH_INSN_DEF (def, insn) |
126 | if (HARD_REGISTER_NUM_P (DF_REF_REGNO (def)) | |
127 | && global_regs[DF_REF_REGNO (def)]) | |
211d71a7 | 128 | return false; |
56873e13 ES |
129 | /* Initialization of pseudo PIC register should never be removed. */ |
130 | else if (DF_REF_REG (def) == pic_offset_table_rtx | |
131 | && REGNO (pic_offset_table_rtx) >= FIRST_PSEUDO_REGISTER) | |
132 | return false; | |
211d71a7 | 133 | |
45399fdc JJ |
134 | /* Callee-save restores are needed. */ |
135 | if (RTX_FRAME_RELATED_P (insn) | |
136 | && crtl->shrink_wrapped_separate | |
137 | && find_reg_note (insn, REG_CFA_RESTORE, NULL)) | |
138 | return false; | |
139 | ||
d4d7f1d1 RS |
140 | body = PATTERN (insn); |
141 | switch (GET_CODE (body)) | |
142 | { | |
143 | case USE: | |
b5b8b0ac | 144 | case VAR_LOCATION: |
d4d7f1d1 RS |
145 | return false; |
146 | ||
6fb5fa3c DB |
147 | case CLOBBER: |
148 | if (fast) | |
149 | { | |
150 | /* A CLOBBER of a dead pseudo register serves no purpose. | |
151 | That is not necessarily true for hard registers until | |
152 | after reload. */ | |
6cad9859 | 153 | x = XEXP (body, 0); |
6fb5fa3c DB |
154 | return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed); |
155 | } | |
d4d7f1d1 | 156 | else |
6fb5fa3c DB |
157 | /* Because of the way that use-def chains are built, it is not |
158 | possible to tell if the clobber is dead because it can | |
159 | never be the target of a use-def chain. */ | |
160 | return false; | |
161 | ||
6cad9859 | 162 | case PARALLEL: |
d4d7f1d1 RS |
163 | for (i = XVECLEN (body, 0) - 1; i >= 0; i--) |
164 | if (!deletable_insn_p_1 (XVECEXP (body, 0, i))) | |
165 | return false; | |
166 | return true; | |
6cad9859 | 167 | |
6fb5fa3c | 168 | default: |
d4d7f1d1 | 169 | return deletable_insn_p_1 (body); |
6fb5fa3c DB |
170 | } |
171 | } | |
172 | ||
173 | ||
2e6be65e | 174 | /* Return true if INSN has been marked as needed. */ |
6fb5fa3c DB |
175 | |
176 | static inline int | |
0ece9321 | 177 | marked_insn_p (rtx_insn *insn) |
6fb5fa3c | 178 | { |
50e94c7e SB |
179 | /* Artificial defs are always needed and they do not have an insn. |
180 | We should never see them here. */ | |
181 | gcc_assert (insn); | |
d7c028c0 | 182 | return bitmap_bit_p (marked, INSN_UID (insn)); |
6fb5fa3c DB |
183 | } |
184 | ||
185 | ||
186 | /* If INSN has not yet been marked as needed, mark it now, and add it to | |
187 | the worklist. */ | |
188 | ||
189 | static void | |
0ece9321 | 190 | mark_insn (rtx_insn *insn, bool fast) |
6fb5fa3c DB |
191 | { |
192 | if (!marked_insn_p (insn)) | |
193 | { | |
194 | if (!fast) | |
9771b263 | 195 | worklist.safe_push (insn); |
d7c028c0 | 196 | bitmap_set_bit (marked, INSN_UID (insn)); |
6fb5fa3c DB |
197 | if (dump_file) |
198 | fprintf (dump_file, " Adding insn %d to worklist\n", INSN_UID (insn)); | |
0196c95e JJ |
199 | if (CALL_P (insn) |
200 | && !df_in_progress | |
201 | && !SIBLING_CALL_P (insn) | |
202 | && (RTL_CONST_OR_PURE_CALL_P (insn) | |
203 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
0ece9321 | 204 | find_call_stack_args (as_a <rtx_call_insn *> (insn), true, fast, NULL); |
6fb5fa3c DB |
205 | } |
206 | } | |
207 | ||
208 | ||
209 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
210 | instruction containing DEST. */ | |
211 | ||
212 | static void | |
7bc980e1 | 213 | mark_nonreg_stores_1 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
214 | { |
215 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
0ece9321 | 216 | mark_insn ((rtx_insn *) data, true); |
6fb5fa3c DB |
217 | } |
218 | ||
219 | ||
220 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
221 | instruction containing DEST. */ | |
222 | ||
223 | static void | |
7bc980e1 | 224 | mark_nonreg_stores_2 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
225 | { |
226 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
0ece9321 | 227 | mark_insn ((rtx_insn *) data, false); |
6fb5fa3c DB |
228 | } |
229 | ||
230 | ||
231 | /* Mark INSN if BODY stores to a non-register destination. */ | |
232 | ||
233 | static void | |
0ece9321 | 234 | mark_nonreg_stores (rtx body, rtx_insn *insn, bool fast) |
6fb5fa3c DB |
235 | { |
236 | if (fast) | |
237 | note_stores (body, mark_nonreg_stores_1, insn); | |
238 | else | |
239 | note_stores (body, mark_nonreg_stores_2, insn); | |
240 | } | |
241 | ||
242 | ||
7eb87420 | 243 | /* Return true if a store to SIZE bytes, starting OFF bytes from stack pointer, |
2e0642cd JJ |
244 | is a call argument store, and clear corresponding bits from SP_BYTES |
245 | bitmap if it is. */ | |
246 | ||
247 | static bool | |
7eb87420 RS |
248 | check_argument_store (HOST_WIDE_INT size, HOST_WIDE_INT off, |
249 | HOST_WIDE_INT min_sp_off, HOST_WIDE_INT max_sp_off, | |
250 | bitmap sp_bytes) | |
2e0642cd JJ |
251 | { |
252 | HOST_WIDE_INT byte; | |
7eb87420 | 253 | for (byte = off; byte < off + size; byte++) |
2e0642cd JJ |
254 | { |
255 | if (byte < min_sp_off | |
256 | || byte >= max_sp_off | |
257 | || !bitmap_clear_bit (sp_bytes, byte - min_sp_off)) | |
258 | return false; | |
259 | } | |
260 | return true; | |
261 | } | |
262 | ||
263 | ||
0196c95e JJ |
264 | /* Try to find all stack stores of CALL_INSN arguments if |
265 | ACCUMULATE_OUTGOING_ARGS. If all stack stores have been found | |
266 | and it is therefore safe to eliminate the call, return true, | |
267 | otherwise return false. This function should be first called | |
268 | with DO_MARK false, and only when the CALL_INSN is actually | |
269 | going to be marked called again with DO_MARK true. */ | |
270 | ||
271 | static bool | |
0ece9321 | 272 | find_call_stack_args (rtx_call_insn *call_insn, bool do_mark, bool fast, |
0196c95e JJ |
273 | bitmap arg_stores) |
274 | { | |
0ece9321 DM |
275 | rtx p; |
276 | rtx_insn *insn, *prev_insn; | |
0196c95e JJ |
277 | bool ret; |
278 | HOST_WIDE_INT min_sp_off, max_sp_off; | |
279 | bitmap sp_bytes; | |
280 | ||
281 | gcc_assert (CALL_P (call_insn)); | |
282 | if (!ACCUMULATE_OUTGOING_ARGS) | |
283 | return true; | |
284 | ||
285 | if (!do_mark) | |
286 | { | |
287 | gcc_assert (arg_stores); | |
288 | bitmap_clear (arg_stores); | |
289 | } | |
290 | ||
291 | min_sp_off = INTTYPE_MAXIMUM (HOST_WIDE_INT); | |
292 | max_sp_off = 0; | |
293 | ||
294 | /* First determine the minimum and maximum offset from sp for | |
295 | stored arguments. */ | |
296 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
297 | if (GET_CODE (XEXP (p, 0)) == USE | |
298 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
299 | { | |
f5541398 RS |
300 | rtx mem = XEXP (XEXP (p, 0), 0), addr; |
301 | HOST_WIDE_INT off = 0, size; | |
d05d7551 | 302 | if (!MEM_SIZE_KNOWN_P (mem) || !MEM_SIZE (mem).is_constant (&size)) |
0196c95e JJ |
303 | return false; |
304 | addr = XEXP (mem, 0); | |
305 | if (GET_CODE (addr) == PLUS | |
306 | && REG_P (XEXP (addr, 0)) | |
307 | && CONST_INT_P (XEXP (addr, 1))) | |
308 | { | |
309 | off = INTVAL (XEXP (addr, 1)); | |
310 | addr = XEXP (addr, 0); | |
311 | } | |
312 | if (addr != stack_pointer_rtx) | |
313 | { | |
314 | if (!REG_P (addr)) | |
315 | return false; | |
316 | /* If not fast, use chains to see if addr wasn't set to | |
317 | sp + offset. */ | |
318 | if (!fast) | |
319 | { | |
bfac633a | 320 | df_ref use; |
0196c95e JJ |
321 | struct df_link *defs; |
322 | rtx set; | |
323 | ||
bfac633a RS |
324 | FOR_EACH_INSN_USE (use, call_insn) |
325 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
326 | break; |
327 | ||
bfac633a | 328 | if (use == NULL) |
0196c95e JJ |
329 | return false; |
330 | ||
bfac633a | 331 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
332 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
333 | break; | |
334 | ||
335 | if (defs == NULL) | |
336 | return false; | |
337 | ||
338 | set = single_set (DF_REF_INSN (defs->ref)); | |
339 | if (!set) | |
340 | return false; | |
341 | ||
342 | if (GET_CODE (SET_SRC (set)) != PLUS | |
343 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
344 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
345 | return false; | |
346 | ||
347 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
348 | } | |
349 | else | |
350 | return false; | |
351 | } | |
352 | min_sp_off = MIN (min_sp_off, off); | |
f5541398 | 353 | max_sp_off = MAX (max_sp_off, off + size); |
0196c95e JJ |
354 | } |
355 | ||
356 | if (min_sp_off >= max_sp_off) | |
357 | return true; | |
358 | sp_bytes = BITMAP_ALLOC (NULL); | |
359 | ||
360 | /* Set bits in SP_BYTES bitmap for bytes relative to sp + min_sp_off | |
361 | which contain arguments. Checking has been done in the previous | |
362 | loop. */ | |
363 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
364 | if (GET_CODE (XEXP (p, 0)) == USE | |
365 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
366 | { | |
367 | rtx mem = XEXP (XEXP (p, 0), 0), addr; | |
d05d7551 RS |
368 | HOST_WIDE_INT off = 0, byte, size; |
369 | /* Checked in the previous iteration. */ | |
370 | size = MEM_SIZE (mem).to_constant (); | |
0196c95e JJ |
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 | { | |
bfac633a | 381 | df_ref use; |
0196c95e JJ |
382 | struct df_link *defs; |
383 | rtx set; | |
384 | ||
bfac633a RS |
385 | FOR_EACH_INSN_USE (use, call_insn) |
386 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
387 | break; |
388 | ||
bfac633a | 389 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
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 | } | |
d05d7551 | 396 | for (byte = off; byte < off + size; byte++) |
0196c95e | 397 | { |
821bb7f8 RG |
398 | if (!bitmap_set_bit (sp_bytes, byte - min_sp_off)) |
399 | gcc_unreachable (); | |
0196c95e JJ |
400 | } |
401 | } | |
402 | ||
403 | /* Walk backwards, looking for argument stores. The search stops | |
750900db | 404 | when seeing another call, sp adjustment or memory store other than |
0196c95e JJ |
405 | argument store. */ |
406 | ret = false; | |
407 | for (insn = PREV_INSN (call_insn); insn; insn = prev_insn) | |
408 | { | |
409 | rtx set, mem, addr; | |
2e0642cd | 410 | HOST_WIDE_INT off; |
0196c95e JJ |
411 | |
412 | if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn))) | |
0ece9321 | 413 | prev_insn = NULL; |
0196c95e JJ |
414 | else |
415 | prev_insn = PREV_INSN (insn); | |
416 | ||
417 | if (CALL_P (insn)) | |
418 | break; | |
419 | ||
2e0642cd | 420 | if (!NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
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 | { | |
bfac633a | 446 | df_ref use; |
0196c95e JJ |
447 | struct df_link *defs; |
448 | rtx set; | |
449 | ||
bfac633a RS |
450 | FOR_EACH_INSN_USE (use, insn) |
451 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
452 | break; |
453 | ||
bfac633a | 454 | if (use == NULL) |
0196c95e JJ |
455 | break; |
456 | ||
bfac633a | 457 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
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 | ||
d05d7551 | 479 | HOST_WIDE_INT size; |
7eb87420 | 480 | if (!MEM_SIZE_KNOWN_P (mem) |
d05d7551 RS |
481 | || !MEM_SIZE (mem).is_constant (&size) |
482 | || !check_argument_store (size, off, min_sp_off, | |
2e0642cd | 483 | max_sp_off, sp_bytes)) |
0196c95e JJ |
484 | break; |
485 | ||
0196c95e JJ |
486 | if (!deletable_insn_p (insn, fast, NULL)) |
487 | break; | |
488 | ||
489 | if (do_mark) | |
490 | mark_insn (insn, fast); | |
491 | else | |
492 | bitmap_set_bit (arg_stores, INSN_UID (insn)); | |
493 | ||
494 | if (bitmap_empty_p (sp_bytes)) | |
495 | { | |
496 | ret = true; | |
497 | break; | |
498 | } | |
499 | } | |
500 | ||
501 | BITMAP_FREE (sp_bytes); | |
502 | if (!ret && arg_stores) | |
503 | bitmap_clear (arg_stores); | |
504 | ||
505 | return ret; | |
506 | } | |
507 | ||
508 | ||
885c9b5d EB |
509 | /* Remove all REG_EQUAL and REG_EQUIV notes referring to the registers INSN |
510 | writes to. */ | |
6fb5fa3c DB |
511 | |
512 | static void | |
0ece9321 | 513 | remove_reg_equal_equiv_notes_for_defs (rtx_insn *insn) |
6fb5fa3c | 514 | { |
bfac633a | 515 | df_ref def; |
885c9b5d | 516 | |
bfac633a RS |
517 | FOR_EACH_INSN_DEF (def, insn) |
518 | remove_reg_equal_equiv_notes_for_regno (DF_REF_REGNO (def)); | |
6fb5fa3c DB |
519 | } |
520 | ||
a7a110bb AO |
521 | /* Scan all BBs for debug insns and reset those that reference values |
522 | defined in unmarked insns. */ | |
523 | ||
524 | static void | |
525 | reset_unmarked_insns_debug_uses (void) | |
526 | { | |
527 | basic_block bb; | |
0ece9321 | 528 | rtx_insn *insn, *next; |
a7a110bb | 529 | |
4f42035e | 530 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
a7a110bb AO |
531 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
532 | if (DEBUG_INSN_P (insn)) | |
533 | { | |
bfac633a | 534 | df_ref use; |
a7a110bb | 535 | |
bfac633a | 536 | FOR_EACH_INSN_USE (use, insn) |
a7a110bb | 537 | { |
a7a110bb AO |
538 | struct df_link *defs; |
539 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
540 | { | |
0ece9321 | 541 | rtx_insn *ref_insn; |
a7a110bb AO |
542 | if (DF_REF_IS_ARTIFICIAL (defs->ref)) |
543 | continue; | |
8ced31fe JJ |
544 | ref_insn = DF_REF_INSN (defs->ref); |
545 | if (!marked_insn_p (ref_insn)) | |
a7a110bb AO |
546 | break; |
547 | } | |
548 | if (!defs) | |
549 | continue; | |
550 | /* ??? FIXME could we propagate the values assigned to | |
551 | each of the DEFs? */ | |
552 | INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC (); | |
553 | df_insn_rescan_debug_internal (insn); | |
8ced31fe | 554 | break; |
a7a110bb AO |
555 | } |
556 | } | |
557 | } | |
6fb5fa3c | 558 | |
9ed7b221 | 559 | /* Delete every instruction that hasn't been marked. */ |
6fb5fa3c DB |
560 | |
561 | static void | |
562 | delete_unmarked_insns (void) | |
563 | { | |
564 | basic_block bb; | |
0ece9321 | 565 | rtx_insn *insn, *next; |
5ba5ab9b | 566 | bool must_clean = false; |
6fb5fa3c | 567 | |
4f42035e | 568 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
cd3f1729 | 569 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
a7a110bb | 570 | if (NONDEBUG_INSN_P (insn)) |
6fb5fa3c | 571 | { |
9ed7b221 | 572 | /* Always delete no-op moves. */ |
6fb5fa3c | 573 | if (noop_move_p (insn)) |
9ed7b221 EB |
574 | ; |
575 | ||
9ed7b221 | 576 | /* Otherwise rely only on the DCE algorithm. */ |
6fb5fa3c DB |
577 | else if (marked_insn_p (insn)) |
578 | continue; | |
579 | ||
cd3f1729 KZ |
580 | /* Beware that reaching a dbg counter limit here can result |
581 | in miscompiled file. This occurs when a group of insns | |
582 | must be deleted together, typically because the kept insn | |
583 | depends on the output from the deleted insn. Deleting | |
584 | this insns in reverse order (both at the bb level and | |
585 | when looking at the blocks) minimizes this, but does not | |
586 | eliminate it, since it is possible for the using insn to | |
587 | be top of a block and the producer to be at the bottom of | |
588 | the block. However, in most cases this will only result | |
589 | in an uninitialized use of an insn that is dead anyway. | |
590 | ||
591 | However, there is one rare case that will cause a | |
592 | miscompile: deletion of non-looping pure and constant | |
593 | calls on a machine where ACCUMULATE_OUTGOING_ARGS is true. | |
594 | In this case it is possible to remove the call, but leave | |
595 | the argument pushes to the stack. Because of the changes | |
596 | to the stack pointer, this will almost always lead to a | |
597 | miscompile. */ | |
6fb5fa3c DB |
598 | if (!dbg_cnt (dce)) |
599 | continue; | |
600 | ||
601 | if (dump_file) | |
602 | fprintf (dump_file, "DCE: Deleting insn %d\n", INSN_UID (insn)); | |
603 | ||
885c9b5d | 604 | /* Before we delete the insn we have to remove the REG_EQUAL notes |
9ed7b221 | 605 | for the destination regs in order to avoid dangling notes. */ |
885c9b5d | 606 | remove_reg_equal_equiv_notes_for_defs (insn); |
6fb5fa3c | 607 | |
5ba5ab9b KZ |
608 | /* If a pure or const call is deleted, this may make the cfg |
609 | have unreachable blocks. We rememeber this and call | |
610 | delete_unreachable_blocks at the end. */ | |
611 | if (CALL_P (insn)) | |
612 | must_clean = true; | |
613 | ||
9ed7b221 | 614 | /* Now delete the insn. */ |
6fb5fa3c | 615 | delete_insn_and_edges (insn); |
6fb5fa3c | 616 | } |
5ba5ab9b KZ |
617 | |
618 | /* Deleted a pure or const call. */ | |
619 | if (must_clean) | |
620 | delete_unreachable_blocks (); | |
6fb5fa3c DB |
621 | } |
622 | ||
623 | ||
6fb5fa3c DB |
624 | /* Go through the instructions and mark those whose necessity is not |
625 | dependent on inter-instruction information. Make sure all other | |
626 | instructions are not marked. */ | |
627 | ||
628 | static void | |
629 | prescan_insns_for_dce (bool fast) | |
630 | { | |
631 | basic_block bb; | |
0ece9321 | 632 | rtx_insn *insn, *prev; |
0196c95e JJ |
633 | bitmap arg_stores = NULL; |
634 | ||
6fb5fa3c DB |
635 | if (dump_file) |
636 | fprintf (dump_file, "Finding needed instructions:\n"); | |
0196c95e JJ |
637 | |
638 | if (!df_in_progress && ACCUMULATE_OUTGOING_ARGS) | |
639 | arg_stores = BITMAP_ALLOC (NULL); | |
640 | ||
11cd3bed | 641 | FOR_EACH_BB_FN (bb, cfun) |
0196c95e JJ |
642 | { |
643 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev) | |
a7a110bb | 644 | if (NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
645 | { |
646 | /* Don't mark argument stores now. They will be marked | |
647 | if needed when the associated CALL is marked. */ | |
648 | if (arg_stores && bitmap_bit_p (arg_stores, INSN_UID (insn))) | |
649 | continue; | |
650 | if (deletable_insn_p (insn, fast, arg_stores)) | |
651 | mark_nonreg_stores (PATTERN (insn), insn, fast); | |
652 | else | |
653 | mark_insn (insn, fast); | |
654 | } | |
655 | /* find_call_stack_args only looks at argument stores in the | |
656 | same bb. */ | |
657 | if (arg_stores) | |
658 | bitmap_clear (arg_stores); | |
659 | } | |
660 | ||
661 | if (arg_stores) | |
662 | BITMAP_FREE (arg_stores); | |
6fb5fa3c DB |
663 | |
664 | if (dump_file) | |
665 | fprintf (dump_file, "Finished finding needed instructions:\n"); | |
666 | } | |
667 | ||
668 | ||
669 | /* UD-based DSE routines. */ | |
670 | ||
6ed3da00 | 671 | /* Mark instructions that define artificially-used registers, such as |
6fb5fa3c DB |
672 | the frame pointer and the stack pointer. */ |
673 | ||
674 | static void | |
675 | mark_artificial_uses (void) | |
676 | { | |
677 | basic_block bb; | |
678 | struct df_link *defs; | |
292321a5 | 679 | df_ref use; |
6fb5fa3c | 680 | |
04a90bec | 681 | FOR_ALL_BB_FN (bb, cfun) |
292321a5 RS |
682 | FOR_EACH_ARTIFICIAL_USE (use, bb->index) |
683 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
684 | if (!DF_REF_IS_ARTIFICIAL (defs->ref)) | |
685 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
686 | } |
687 | ||
2e6be65e | 688 | |
6fb5fa3c DB |
689 | /* Mark every instruction that defines a register value that INSN uses. */ |
690 | ||
691 | static void | |
0ece9321 | 692 | mark_reg_dependencies (rtx_insn *insn) |
6fb5fa3c DB |
693 | { |
694 | struct df_link *defs; | |
bfac633a | 695 | df_ref use; |
6fb5fa3c | 696 | |
b5b8b0ac AO |
697 | if (DEBUG_INSN_P (insn)) |
698 | return; | |
699 | ||
bfac633a | 700 | FOR_EACH_INSN_USE (use, insn) |
6fb5fa3c | 701 | { |
6fb5fa3c DB |
702 | if (dump_file) |
703 | { | |
704 | fprintf (dump_file, "Processing use of "); | |
705 | print_simple_rtl (dump_file, DF_REF_REG (use)); | |
706 | fprintf (dump_file, " in insn %d:\n", INSN_UID (insn)); | |
707 | } | |
708 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
50e94c7e SB |
709 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
710 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
711 | } |
712 | } | |
713 | ||
714 | ||
2e6be65e EB |
715 | /* Initialize global variables for a new DCE pass. */ |
716 | ||
6fb5fa3c | 717 | static void |
2e6be65e EB |
718 | init_dce (bool fast) |
719 | { | |
720 | if (!df_in_progress) | |
721 | { | |
722 | if (!fast) | |
7b19209f SB |
723 | { |
724 | df_set_flags (DF_RD_PRUNE_DEAD_DEFS); | |
725 | df_chain_add_problem (DF_UD_CHAIN); | |
726 | } | |
2e6be65e EB |
727 | df_analyze (); |
728 | } | |
729 | ||
730 | if (dump_file) | |
731 | df_dump (dump_file); | |
732 | ||
733 | if (fast) | |
734 | { | |
735 | bitmap_obstack_initialize (&dce_blocks_bitmap_obstack); | |
736 | bitmap_obstack_initialize (&dce_tmp_bitmap_obstack); | |
2da02156 | 737 | can_alter_cfg = false; |
2e6be65e | 738 | } |
2da02156 EB |
739 | else |
740 | can_alter_cfg = true; | |
2e6be65e EB |
741 | |
742 | marked = sbitmap_alloc (get_max_uid () + 1); | |
f61e445a | 743 | bitmap_clear (marked); |
2e6be65e EB |
744 | } |
745 | ||
746 | ||
747 | /* Free the data allocated by init_dce. */ | |
748 | ||
749 | static void | |
750 | fini_dce (bool fast) | |
6fb5fa3c DB |
751 | { |
752 | sbitmap_free (marked); | |
2e6be65e EB |
753 | |
754 | if (fast) | |
755 | { | |
756 | bitmap_obstack_release (&dce_blocks_bitmap_obstack); | |
757 | bitmap_obstack_release (&dce_tmp_bitmap_obstack); | |
758 | } | |
6fb5fa3c DB |
759 | } |
760 | ||
761 | ||
762 | /* UD-chain based DCE. */ | |
763 | ||
764 | static unsigned int | |
765 | rest_of_handle_ud_dce (void) | |
766 | { | |
0ece9321 | 767 | rtx_insn *insn; |
6fb5fa3c | 768 | |
6fb5fa3c DB |
769 | init_dce (false); |
770 | ||
771 | prescan_insns_for_dce (false); | |
772 | mark_artificial_uses (); | |
9771b263 | 773 | while (worklist.length () > 0) |
6fb5fa3c | 774 | { |
9771b263 | 775 | insn = worklist.pop (); |
6fb5fa3c DB |
776 | mark_reg_dependencies (insn); |
777 | } | |
9771b263 | 778 | worklist.release (); |
2e6be65e | 779 | |
36f52e8f | 780 | if (MAY_HAVE_DEBUG_BIND_INSNS) |
a7a110bb AO |
781 | reset_unmarked_insns_debug_uses (); |
782 | ||
6fb5fa3c DB |
783 | /* Before any insns are deleted, we must remove the chains since |
784 | they are not bidirectional. */ | |
785 | df_remove_problem (df_chain); | |
786 | delete_unmarked_insns (); | |
787 | ||
2e6be65e | 788 | fini_dce (false); |
6fb5fa3c DB |
789 | return 0; |
790 | } | |
791 | ||
792 | ||
17795822 TS |
793 | namespace { |
794 | ||
795 | const pass_data pass_data_ud_rtl_dce = | |
6fb5fa3c | 796 | { |
27a4cd48 DM |
797 | RTL_PASS, /* type */ |
798 | "ud_dce", /* name */ | |
799 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
800 | TV_DCE, /* tv_id */ |
801 | 0, /* properties_required */ | |
802 | 0, /* properties_provided */ | |
803 | 0, /* properties_destroyed */ | |
804 | 0, /* todo_flags_start */ | |
3bea341f | 805 | TODO_df_finish, /* todo_flags_finish */ |
6fb5fa3c DB |
806 | }; |
807 | ||
17795822 | 808 | class pass_ud_rtl_dce : public rtl_opt_pass |
27a4cd48 DM |
809 | { |
810 | public: | |
c3284718 RS |
811 | pass_ud_rtl_dce (gcc::context *ctxt) |
812 | : rtl_opt_pass (pass_data_ud_rtl_dce, ctxt) | |
27a4cd48 DM |
813 | {} |
814 | ||
815 | /* opt_pass methods: */ | |
1a3d085c TS |
816 | virtual bool gate (function *) |
817 | { | |
818 | return optimize > 1 && flag_dce && dbg_cnt (dce_ud); | |
819 | } | |
820 | ||
be55bfe6 TS |
821 | virtual unsigned int execute (function *) |
822 | { | |
823 | return rest_of_handle_ud_dce (); | |
824 | } | |
27a4cd48 DM |
825 | |
826 | }; // class pass_ud_rtl_dce | |
827 | ||
17795822 TS |
828 | } // anon namespace |
829 | ||
27a4cd48 DM |
830 | rtl_opt_pass * |
831 | make_pass_ud_rtl_dce (gcc::context *ctxt) | |
832 | { | |
833 | return new pass_ud_rtl_dce (ctxt); | |
834 | } | |
835 | ||
2e6be65e | 836 | |
6fb5fa3c DB |
837 | /* ------------------------------------------------------------------------- |
838 | Fast DCE functions | |
839 | ------------------------------------------------------------------------- */ | |
840 | ||
cc806ac1 RS |
841 | /* Process basic block BB. Return true if the live_in set has |
842 | changed. REDO_OUT is true if the info at the bottom of the block | |
843 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
844 | artificial uses. Track global substitution of uses of dead pseudos |
845 | in debug insns using GLOBAL_DEBUG. */ | |
6fb5fa3c DB |
846 | |
847 | static bool | |
e9f950ba AO |
848 | word_dce_process_block (basic_block bb, bool redo_out, |
849 | struct dead_debug_global *global_debug) | |
6fb5fa3c DB |
850 | { |
851 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
0ece9321 | 852 | rtx_insn *insn; |
6fb5fa3c | 853 | bool block_changed; |
e9f950ba | 854 | struct dead_debug_local debug; |
6fb5fa3c DB |
855 | |
856 | if (redo_out) | |
857 | { | |
858 | /* Need to redo the live_out set of this block if when one of | |
859 | the succs of this block has had a change in it live in | |
860 | set. */ | |
861 | edge e; | |
862 | edge_iterator ei; | |
8d074192 BS |
863 | df_confluence_function_n con_fun_n = df_word_lr->problem->con_fun_n; |
864 | bitmap_clear (DF_WORD_LR_OUT (bb)); | |
6fb5fa3c DB |
865 | FOR_EACH_EDGE (e, ei, bb->succs) |
866 | (*con_fun_n) (e); | |
867 | } | |
868 | ||
869 | if (dump_file) | |
870 | { | |
871 | fprintf (dump_file, "processing block %d live out = ", bb->index); | |
8d074192 | 872 | df_print_word_regset (dump_file, DF_WORD_LR_OUT (bb)); |
6fb5fa3c DB |
873 | } |
874 | ||
8d074192 | 875 | bitmap_copy (local_live, DF_WORD_LR_OUT (bb)); |
e9f950ba | 876 | dead_debug_local_init (&debug, NULL, global_debug); |
cc806ac1 RS |
877 | |
878 | FOR_BB_INSNS_REVERSE (bb, insn) | |
1adbb361 AO |
879 | if (DEBUG_INSN_P (insn)) |
880 | { | |
bfac633a RS |
881 | df_ref use; |
882 | FOR_EACH_INSN_USE (use, insn) | |
883 | if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER | |
cf098191 RS |
884 | && known_eq (GET_MODE_SIZE (GET_MODE (DF_REF_REAL_REG (use))), |
885 | 2 * UNITS_PER_WORD) | |
bfac633a RS |
886 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use)) |
887 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use) + 1)) | |
888 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
1adbb361 AO |
889 | } |
890 | else if (INSN_P (insn)) | |
cc806ac1 | 891 | { |
8d074192 | 892 | bool any_changed; |
1adbb361 | 893 | |
cc806ac1 RS |
894 | /* No matter if the instruction is needed or not, we remove |
895 | any regno in the defs from the live set. */ | |
8d074192 BS |
896 | any_changed = df_word_lr_simulate_defs (insn, local_live); |
897 | if (any_changed) | |
898 | mark_insn (insn, true); | |
cc806ac1 RS |
899 | |
900 | /* On the other hand, we do not allow the dead uses to set | |
901 | anything in local_live. */ | |
902 | if (marked_insn_p (insn)) | |
8d074192 | 903 | df_word_lr_simulate_uses (insn, local_live); |
6f9e260c | 904 | |
39bc0f01 | 905 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
906 | insns. We may have to emit a debug temp even if the insn |
907 | was marked, in case the debug use was after the point of | |
908 | death. */ | |
909 | if (debug.used && !bitmap_empty_p (debug.used)) | |
1adbb361 | 910 | { |
bfac633a | 911 | df_ref def; |
1adbb361 | 912 | |
bfac633a RS |
913 | FOR_EACH_INSN_DEF (def, insn) |
914 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
85d87497 JJ |
915 | marked_insn_p (insn) |
916 | && !control_flow_insn_p (insn) | |
917 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
918 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
1adbb361 AO |
919 | } |
920 | ||
cc806ac1 RS |
921 | if (dump_file) |
922 | { | |
b8698a0f | 923 | fprintf (dump_file, "finished processing insn %d live out = ", |
cc806ac1 | 924 | INSN_UID (insn)); |
8d074192 | 925 | df_print_word_regset (dump_file, local_live); |
cc806ac1 RS |
926 | } |
927 | } | |
b8698a0f | 928 | |
8d074192 | 929 | block_changed = !bitmap_equal_p (local_live, DF_WORD_LR_IN (bb)); |
cc806ac1 | 930 | if (block_changed) |
8d074192 BS |
931 | bitmap_copy (DF_WORD_LR_IN (bb), local_live); |
932 | ||
e9f950ba | 933 | dead_debug_local_finish (&debug, NULL); |
cc806ac1 RS |
934 | BITMAP_FREE (local_live); |
935 | return block_changed; | |
936 | } | |
937 | ||
938 | ||
939 | /* Process basic block BB. Return true if the live_in set has | |
940 | changed. REDO_OUT is true if the info at the bottom of the block | |
941 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
942 | artificial uses. Track global substitution of uses of dead pseudos |
943 | in debug insns using GLOBAL_DEBUG. */ | |
cc806ac1 RS |
944 | |
945 | static bool | |
e9f950ba AO |
946 | dce_process_block (basic_block bb, bool redo_out, bitmap au, |
947 | struct dead_debug_global *global_debug) | |
cc806ac1 RS |
948 | { |
949 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
0ece9321 | 950 | rtx_insn *insn; |
cc806ac1 | 951 | bool block_changed; |
bfac633a | 952 | df_ref def; |
e9f950ba | 953 | struct dead_debug_local debug; |
6fb5fa3c | 954 | |
cc806ac1 | 955 | if (redo_out) |
6fb5fa3c | 956 | { |
cc806ac1 RS |
957 | /* Need to redo the live_out set of this block if when one of |
958 | the succs of this block has had a change in it live in | |
959 | set. */ | |
960 | edge e; | |
961 | edge_iterator ei; | |
962 | df_confluence_function_n con_fun_n = df_lr->problem->con_fun_n; | |
963 | bitmap_clear (DF_LR_OUT (bb)); | |
964 | FOR_EACH_EDGE (e, ei, bb->succs) | |
965 | (*con_fun_n) (e); | |
6fb5fa3c DB |
966 | } |
967 | ||
cc806ac1 | 968 | if (dump_file) |
6fb5fa3c | 969 | { |
fafe34f9 | 970 | fprintf (dump_file, "processing block %d lr out = ", bb->index); |
cc806ac1 | 971 | df_print_regset (dump_file, DF_LR_OUT (bb)); |
6fb5fa3c DB |
972 | } |
973 | ||
cc806ac1 RS |
974 | bitmap_copy (local_live, DF_LR_OUT (bb)); |
975 | ||
02b47899 | 976 | df_simulate_initialize_backwards (bb, local_live); |
e9f950ba | 977 | dead_debug_local_init (&debug, NULL, global_debug); |
541d3103 | 978 | |
6fb5fa3c | 979 | FOR_BB_INSNS_REVERSE (bb, insn) |
1adbb361 AO |
980 | if (DEBUG_INSN_P (insn)) |
981 | { | |
bfac633a RS |
982 | df_ref use; |
983 | FOR_EACH_INSN_USE (use, insn) | |
984 | if (!bitmap_bit_p (local_live, DF_REF_REGNO (use)) | |
985 | && !bitmap_bit_p (au, DF_REF_REGNO (use))) | |
986 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
1adbb361 AO |
987 | } |
988 | else if (INSN_P (insn)) | |
6fb5fa3c | 989 | { |
f251709a | 990 | bool needed = marked_insn_p (insn); |
9ed7b221 EB |
991 | |
992 | /* The insn is needed if there is someone who uses the output. */ | |
f251709a | 993 | if (!needed) |
bfac633a RS |
994 | FOR_EACH_INSN_DEF (def, insn) |
995 | if (bitmap_bit_p (local_live, DF_REF_REGNO (def)) | |
996 | || bitmap_bit_p (au, DF_REF_REGNO (def))) | |
39bc0f01 AO |
997 | { |
998 | needed = true; | |
999 | mark_insn (insn, true); | |
1000 | break; | |
1001 | } | |
b8698a0f | 1002 | |
6fb5fa3c DB |
1003 | /* No matter if the instruction is needed or not, we remove |
1004 | any regno in the defs from the live set. */ | |
1005 | df_simulate_defs (insn, local_live); | |
1006 | ||
1007 | /* On the other hand, we do not allow the dead uses to set | |
1008 | anything in local_live. */ | |
f251709a | 1009 | if (needed) |
6fb5fa3c | 1010 | df_simulate_uses (insn, local_live); |
6f9e260c | 1011 | |
39bc0f01 | 1012 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
1013 | insns. We may have to emit a debug temp even if the insn |
1014 | was marked, in case the debug use was after the point of | |
1015 | death. */ | |
1016 | if (debug.used && !bitmap_empty_p (debug.used)) | |
bfac633a RS |
1017 | FOR_EACH_INSN_DEF (def, insn) |
1018 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
85d87497 JJ |
1019 | needed && !control_flow_insn_p (insn) |
1020 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
1021 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
6fb5fa3c | 1022 | } |
b8698a0f | 1023 | |
e9f950ba | 1024 | dead_debug_local_finish (&debug, NULL); |
02b47899 | 1025 | df_simulate_finalize_backwards (bb, local_live); |
6fb5fa3c DB |
1026 | |
1027 | block_changed = !bitmap_equal_p (local_live, DF_LR_IN (bb)); | |
1028 | if (block_changed) | |
1029 | bitmap_copy (DF_LR_IN (bb), local_live); | |
1030 | ||
1031 | BITMAP_FREE (local_live); | |
1032 | return block_changed; | |
1033 | } | |
1034 | ||
2e6be65e | 1035 | |
8d074192 BS |
1036 | /* Perform fast DCE once initialization is done. If WORD_LEVEL is |
1037 | true, use the word level dce, otherwise do it at the pseudo | |
cc806ac1 | 1038 | level. */ |
2e6be65e | 1039 | |
6fb5fa3c | 1040 | static void |
8d074192 | 1041 | fast_dce (bool word_level) |
6fb5fa3c DB |
1042 | { |
1043 | int *postorder = df_get_postorder (DF_BACKWARD); | |
1044 | int n_blocks = df_get_n_blocks (DF_BACKWARD); | |
6fb5fa3c DB |
1045 | /* The set of blocks that have been seen on this iteration. */ |
1046 | bitmap processed = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1047 | /* The set of blocks that need to have the out vectors reset because | |
1048 | the in of one of their successors has changed. */ | |
1049 | bitmap redo_out = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1050 | bitmap all_blocks = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1051 | bool global_changed = true; | |
cc806ac1 RS |
1052 | |
1053 | /* These regs are considered always live so if they end up dying | |
1054 | because of some def, we need to bring the back again. Calling | |
1055 | df_simulate_fixup_sets has the disadvantage of calling | |
1056 | bb_has_eh_pred once per insn, so we cache the information | |
1057 | here. */ | |
a7e3698d JH |
1058 | bitmap au = &df->regular_block_artificial_uses; |
1059 | bitmap au_eh = &df->eh_block_artificial_uses; | |
9ed7b221 | 1060 | int i; |
e9f950ba | 1061 | struct dead_debug_global global_debug; |
6fb5fa3c DB |
1062 | |
1063 | prescan_insns_for_dce (true); | |
1064 | ||
1065 | for (i = 0; i < n_blocks; i++) | |
1066 | bitmap_set_bit (all_blocks, postorder[i]); | |
1067 | ||
e9f950ba AO |
1068 | dead_debug_global_init (&global_debug, NULL); |
1069 | ||
6fb5fa3c DB |
1070 | while (global_changed) |
1071 | { | |
1072 | global_changed = false; | |
9ed7b221 | 1073 | |
6fb5fa3c DB |
1074 | for (i = 0; i < n_blocks; i++) |
1075 | { | |
1076 | int index = postorder[i]; | |
06e28de2 | 1077 | basic_block bb = BASIC_BLOCK_FOR_FN (cfun, index); |
6fb5fa3c DB |
1078 | bool local_changed; |
1079 | ||
1080 | if (index < NUM_FIXED_BLOCKS) | |
1081 | { | |
1082 | bitmap_set_bit (processed, index); | |
1083 | continue; | |
1084 | } | |
1085 | ||
8d074192 | 1086 | if (word_level) |
b8698a0f | 1087 | local_changed |
e9f950ba AO |
1088 | = word_dce_process_block (bb, bitmap_bit_p (redo_out, index), |
1089 | &global_debug); | |
cc806ac1 | 1090 | else |
b8698a0f | 1091 | local_changed |
cc806ac1 | 1092 | = dce_process_block (bb, bitmap_bit_p (redo_out, index), |
e9f950ba AO |
1093 | bb_has_eh_pred (bb) ? au_eh : au, |
1094 | &global_debug); | |
6fb5fa3c | 1095 | bitmap_set_bit (processed, index); |
b8698a0f | 1096 | |
6fb5fa3c DB |
1097 | if (local_changed) |
1098 | { | |
1099 | edge e; | |
1100 | edge_iterator ei; | |
1101 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1102 | if (bitmap_bit_p (processed, e->src->index)) | |
1103 | /* Be tricky about when we need to iterate the | |
1104 | analysis. We only have redo the analysis if the | |
1105 | bitmaps change at the top of a block that is the | |
1106 | entry to a loop. */ | |
1107 | global_changed = true; | |
1108 | else | |
1109 | bitmap_set_bit (redo_out, e->src->index); | |
1110 | } | |
1111 | } | |
b8698a0f | 1112 | |
6fb5fa3c DB |
1113 | if (global_changed) |
1114 | { | |
1115 | /* Turn off the RUN_DCE flag to prevent recursive calls to | |
1116 | dce. */ | |
1117 | int old_flag = df_clear_flags (DF_LR_RUN_DCE); | |
1118 | ||
1119 | /* So something was deleted that requires a redo. Do it on | |
1120 | the cheap. */ | |
1121 | delete_unmarked_insns (); | |
f61e445a | 1122 | bitmap_clear (marked); |
6fb5fa3c DB |
1123 | bitmap_clear (processed); |
1124 | bitmap_clear (redo_out); | |
b8698a0f | 1125 | |
6fb5fa3c DB |
1126 | /* We do not need to rescan any instructions. We only need |
1127 | to redo the dataflow equations for the blocks that had a | |
1128 | change at the top of the block. Then we need to redo the | |
b8698a0f | 1129 | iteration. */ |
8d074192 BS |
1130 | if (word_level) |
1131 | df_analyze_problem (df_word_lr, all_blocks, postorder, n_blocks); | |
cc806ac1 RS |
1132 | else |
1133 | df_analyze_problem (df_lr, all_blocks, postorder, n_blocks); | |
6fb5fa3c DB |
1134 | |
1135 | if (old_flag & DF_LR_RUN_DCE) | |
1136 | df_set_flags (DF_LR_RUN_DCE); | |
9ed7b221 | 1137 | |
6fb5fa3c DB |
1138 | prescan_insns_for_dce (true); |
1139 | } | |
6fb5fa3c DB |
1140 | } |
1141 | ||
e9f950ba AO |
1142 | dead_debug_global_finish (&global_debug, NULL); |
1143 | ||
6fb5fa3c DB |
1144 | delete_unmarked_insns (); |
1145 | ||
1146 | BITMAP_FREE (processed); | |
1147 | BITMAP_FREE (redo_out); | |
1148 | BITMAP_FREE (all_blocks); | |
1149 | } | |
1150 | ||
1151 | ||
cc806ac1 | 1152 | /* Fast register level DCE. */ |
6fb5fa3c DB |
1153 | |
1154 | static unsigned int | |
1155 | rest_of_handle_fast_dce (void) | |
1156 | { | |
1157 | init_dce (true); | |
cc806ac1 RS |
1158 | fast_dce (false); |
1159 | fini_dce (true); | |
1160 | return 0; | |
1161 | } | |
1162 | ||
1163 | ||
1164 | /* Fast byte level DCE. */ | |
1165 | ||
8d074192 BS |
1166 | void |
1167 | run_word_dce (void) | |
cc806ac1 | 1168 | { |
25aef556 BS |
1169 | int old_flags; |
1170 | ||
1171 | if (!flag_dce) | |
1172 | return; | |
1173 | ||
8d074192 | 1174 | timevar_push (TV_DCE); |
25aef556 | 1175 | old_flags = df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
8d074192 | 1176 | df_word_lr_add_problem (); |
cc806ac1 RS |
1177 | init_dce (true); |
1178 | fast_dce (true); | |
2e6be65e | 1179 | fini_dce (true); |
25aef556 | 1180 | df_set_flags (old_flags); |
8d074192 | 1181 | timevar_pop (TV_DCE); |
6fb5fa3c DB |
1182 | } |
1183 | ||
1184 | ||
1185 | /* This is an internal call that is used by the df live register | |
1186 | problem to run fast dce as a side effect of creating the live | |
1187 | information. The stack is organized so that the lr problem is run, | |
1188 | this pass is run, which updates the live info and the df scanning | |
1189 | info, and then returns to allow the rest of the problems to be run. | |
1190 | ||
1191 | This can be called by elsewhere but it will not update the bit | |
2e6be65e | 1192 | vectors for any other problems than LR. */ |
6fb5fa3c DB |
1193 | |
1194 | void | |
1195 | run_fast_df_dce (void) | |
1196 | { | |
1197 | if (flag_dce) | |
1198 | { | |
1199 | /* If dce is able to delete something, it has to happen | |
1200 | immediately. Otherwise there will be problems handling the | |
1201 | eq_notes. */ | |
81f40b79 ILT |
1202 | int old_flags = |
1203 | df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); | |
1204 | ||
6fb5fa3c DB |
1205 | df_in_progress = true; |
1206 | rest_of_handle_fast_dce (); | |
2e6be65e EB |
1207 | df_in_progress = false; |
1208 | ||
6fb5fa3c DB |
1209 | df_set_flags (old_flags); |
1210 | } | |
1211 | } | |
1212 | ||
2e6be65e | 1213 | |
9ed7b221 EB |
1214 | /* Run a fast DCE pass. */ |
1215 | ||
1216 | void | |
1217 | run_fast_dce (void) | |
6fb5fa3c | 1218 | { |
9ed7b221 EB |
1219 | if (flag_dce) |
1220 | rest_of_handle_fast_dce (); | |
6fb5fa3c DB |
1221 | } |
1222 | ||
1223 | ||
17795822 TS |
1224 | namespace { |
1225 | ||
1226 | const pass_data pass_data_fast_rtl_dce = | |
6fb5fa3c | 1227 | { |
27a4cd48 DM |
1228 | RTL_PASS, /* type */ |
1229 | "rtl_dce", /* name */ | |
1230 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
1231 | TV_DCE, /* tv_id */ |
1232 | 0, /* properties_required */ | |
1233 | 0, /* properties_provided */ | |
1234 | 0, /* properties_destroyed */ | |
1235 | 0, /* todo_flags_start */ | |
3bea341f | 1236 | TODO_df_finish, /* todo_flags_finish */ |
6fb5fa3c | 1237 | }; |
27a4cd48 | 1238 | |
17795822 | 1239 | class pass_fast_rtl_dce : public rtl_opt_pass |
27a4cd48 DM |
1240 | { |
1241 | public: | |
c3284718 RS |
1242 | pass_fast_rtl_dce (gcc::context *ctxt) |
1243 | : rtl_opt_pass (pass_data_fast_rtl_dce, ctxt) | |
27a4cd48 DM |
1244 | {} |
1245 | ||
1246 | /* opt_pass methods: */ | |
1a3d085c TS |
1247 | virtual bool gate (function *) |
1248 | { | |
1249 | return optimize > 0 && flag_dce && dbg_cnt (dce_fast); | |
1250 | } | |
1251 | ||
be55bfe6 TS |
1252 | virtual unsigned int execute (function *) |
1253 | { | |
1254 | return rest_of_handle_fast_dce (); | |
1255 | } | |
27a4cd48 DM |
1256 | |
1257 | }; // class pass_fast_rtl_dce | |
1258 | ||
17795822 TS |
1259 | } // anon namespace |
1260 | ||
27a4cd48 DM |
1261 | rtl_opt_pass * |
1262 | make_pass_fast_rtl_dce (gcc::context *ctxt) | |
1263 | { | |
1264 | return new pass_fast_rtl_dce (ctxt); | |
1265 | } |