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6fb5fa3c | 1 | /* RTL dead code elimination. |
a5544970 | 2 | Copyright (C) 2005-2019 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 | 147 | case CLOBBER: |
8df47bdf | 148 | case CLOBBER_HIGH: |
6fb5fa3c DB |
149 | if (fast) |
150 | { | |
151 | /* A CLOBBER of a dead pseudo register serves no purpose. | |
152 | That is not necessarily true for hard registers until | |
153 | after reload. */ | |
6cad9859 | 154 | x = XEXP (body, 0); |
6fb5fa3c DB |
155 | return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed); |
156 | } | |
d4d7f1d1 | 157 | else |
6fb5fa3c DB |
158 | /* Because of the way that use-def chains are built, it is not |
159 | possible to tell if the clobber is dead because it can | |
160 | never be the target of a use-def chain. */ | |
161 | return false; | |
162 | ||
6cad9859 | 163 | case PARALLEL: |
d4d7f1d1 RS |
164 | for (i = XVECLEN (body, 0) - 1; i >= 0; i--) |
165 | if (!deletable_insn_p_1 (XVECEXP (body, 0, i))) | |
166 | return false; | |
167 | return true; | |
6cad9859 | 168 | |
6fb5fa3c | 169 | default: |
d4d7f1d1 | 170 | return deletable_insn_p_1 (body); |
6fb5fa3c DB |
171 | } |
172 | } | |
173 | ||
174 | ||
2e6be65e | 175 | /* Return true if INSN has been marked as needed. */ |
6fb5fa3c DB |
176 | |
177 | static inline int | |
0ece9321 | 178 | marked_insn_p (rtx_insn *insn) |
6fb5fa3c | 179 | { |
50e94c7e SB |
180 | /* Artificial defs are always needed and they do not have an insn. |
181 | We should never see them here. */ | |
182 | gcc_assert (insn); | |
d7c028c0 | 183 | return bitmap_bit_p (marked, INSN_UID (insn)); |
6fb5fa3c DB |
184 | } |
185 | ||
186 | ||
187 | /* If INSN has not yet been marked as needed, mark it now, and add it to | |
188 | the worklist. */ | |
189 | ||
190 | static void | |
0ece9321 | 191 | mark_insn (rtx_insn *insn, bool fast) |
6fb5fa3c DB |
192 | { |
193 | if (!marked_insn_p (insn)) | |
194 | { | |
195 | if (!fast) | |
9771b263 | 196 | worklist.safe_push (insn); |
d7c028c0 | 197 | bitmap_set_bit (marked, INSN_UID (insn)); |
6fb5fa3c DB |
198 | if (dump_file) |
199 | fprintf (dump_file, " Adding insn %d to worklist\n", INSN_UID (insn)); | |
0196c95e JJ |
200 | if (CALL_P (insn) |
201 | && !df_in_progress | |
202 | && !SIBLING_CALL_P (insn) | |
203 | && (RTL_CONST_OR_PURE_CALL_P (insn) | |
204 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
0ece9321 | 205 | find_call_stack_args (as_a <rtx_call_insn *> (insn), true, fast, NULL); |
6fb5fa3c DB |
206 | } |
207 | } | |
208 | ||
209 | ||
210 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
211 | instruction containing DEST. */ | |
212 | ||
213 | static void | |
7bc980e1 | 214 | mark_nonreg_stores_1 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
215 | { |
216 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
8df47bdf AH |
217 | { |
218 | gcc_checking_assert (GET_CODE (pattern) != CLOBBER_HIGH); | |
219 | mark_insn ((rtx_insn *) data, true); | |
220 | } | |
6fb5fa3c DB |
221 | } |
222 | ||
223 | ||
224 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
225 | instruction containing DEST. */ | |
226 | ||
227 | static void | |
7bc980e1 | 228 | mark_nonreg_stores_2 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
229 | { |
230 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
8df47bdf AH |
231 | { |
232 | gcc_checking_assert (GET_CODE (pattern) != CLOBBER_HIGH); | |
233 | mark_insn ((rtx_insn *) data, false); | |
234 | } | |
6fb5fa3c DB |
235 | } |
236 | ||
237 | ||
238 | /* Mark INSN if BODY stores to a non-register destination. */ | |
239 | ||
240 | static void | |
0ece9321 | 241 | mark_nonreg_stores (rtx body, rtx_insn *insn, bool fast) |
6fb5fa3c DB |
242 | { |
243 | if (fast) | |
244 | note_stores (body, mark_nonreg_stores_1, insn); | |
245 | else | |
246 | note_stores (body, mark_nonreg_stores_2, insn); | |
247 | } | |
248 | ||
249 | ||
7eb87420 | 250 | /* Return true if a store to SIZE bytes, starting OFF bytes from stack pointer, |
2e0642cd JJ |
251 | is a call argument store, and clear corresponding bits from SP_BYTES |
252 | bitmap if it is. */ | |
253 | ||
254 | static bool | |
7eb87420 RS |
255 | check_argument_store (HOST_WIDE_INT size, HOST_WIDE_INT off, |
256 | HOST_WIDE_INT min_sp_off, HOST_WIDE_INT max_sp_off, | |
257 | bitmap sp_bytes) | |
2e0642cd JJ |
258 | { |
259 | HOST_WIDE_INT byte; | |
7eb87420 | 260 | for (byte = off; byte < off + size; byte++) |
2e0642cd JJ |
261 | { |
262 | if (byte < min_sp_off | |
263 | || byte >= max_sp_off | |
264 | || !bitmap_clear_bit (sp_bytes, byte - min_sp_off)) | |
265 | return false; | |
266 | } | |
267 | return true; | |
268 | } | |
269 | ||
270 | ||
0196c95e JJ |
271 | /* Try to find all stack stores of CALL_INSN arguments if |
272 | ACCUMULATE_OUTGOING_ARGS. If all stack stores have been found | |
273 | and it is therefore safe to eliminate the call, return true, | |
274 | otherwise return false. This function should be first called | |
275 | with DO_MARK false, and only when the CALL_INSN is actually | |
276 | going to be marked called again with DO_MARK true. */ | |
277 | ||
278 | static bool | |
0ece9321 | 279 | find_call_stack_args (rtx_call_insn *call_insn, bool do_mark, bool fast, |
0196c95e JJ |
280 | bitmap arg_stores) |
281 | { | |
0ece9321 DM |
282 | rtx p; |
283 | rtx_insn *insn, *prev_insn; | |
0196c95e JJ |
284 | bool ret; |
285 | HOST_WIDE_INT min_sp_off, max_sp_off; | |
286 | bitmap sp_bytes; | |
287 | ||
288 | gcc_assert (CALL_P (call_insn)); | |
289 | if (!ACCUMULATE_OUTGOING_ARGS) | |
290 | return true; | |
291 | ||
292 | if (!do_mark) | |
293 | { | |
294 | gcc_assert (arg_stores); | |
295 | bitmap_clear (arg_stores); | |
296 | } | |
297 | ||
298 | min_sp_off = INTTYPE_MAXIMUM (HOST_WIDE_INT); | |
299 | max_sp_off = 0; | |
300 | ||
301 | /* First determine the minimum and maximum offset from sp for | |
302 | stored arguments. */ | |
303 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
304 | if (GET_CODE (XEXP (p, 0)) == USE | |
305 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
306 | { | |
f5541398 RS |
307 | rtx mem = XEXP (XEXP (p, 0), 0), addr; |
308 | HOST_WIDE_INT off = 0, size; | |
d05d7551 | 309 | if (!MEM_SIZE_KNOWN_P (mem) || !MEM_SIZE (mem).is_constant (&size)) |
0196c95e JJ |
310 | return false; |
311 | addr = XEXP (mem, 0); | |
312 | if (GET_CODE (addr) == PLUS | |
313 | && REG_P (XEXP (addr, 0)) | |
314 | && CONST_INT_P (XEXP (addr, 1))) | |
315 | { | |
316 | off = INTVAL (XEXP (addr, 1)); | |
317 | addr = XEXP (addr, 0); | |
318 | } | |
319 | if (addr != stack_pointer_rtx) | |
320 | { | |
321 | if (!REG_P (addr)) | |
322 | return false; | |
323 | /* If not fast, use chains to see if addr wasn't set to | |
324 | sp + offset. */ | |
325 | if (!fast) | |
326 | { | |
bfac633a | 327 | df_ref use; |
0196c95e JJ |
328 | struct df_link *defs; |
329 | rtx set; | |
330 | ||
bfac633a RS |
331 | FOR_EACH_INSN_USE (use, call_insn) |
332 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
333 | break; |
334 | ||
bfac633a | 335 | if (use == NULL) |
0196c95e JJ |
336 | return false; |
337 | ||
bfac633a | 338 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
339 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
340 | break; | |
341 | ||
342 | if (defs == NULL) | |
343 | return false; | |
344 | ||
345 | set = single_set (DF_REF_INSN (defs->ref)); | |
346 | if (!set) | |
347 | return false; | |
348 | ||
349 | if (GET_CODE (SET_SRC (set)) != PLUS | |
350 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
351 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
352 | return false; | |
353 | ||
354 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
355 | } | |
356 | else | |
357 | return false; | |
358 | } | |
359 | min_sp_off = MIN (min_sp_off, off); | |
f5541398 | 360 | max_sp_off = MAX (max_sp_off, off + size); |
0196c95e JJ |
361 | } |
362 | ||
363 | if (min_sp_off >= max_sp_off) | |
364 | return true; | |
365 | sp_bytes = BITMAP_ALLOC (NULL); | |
366 | ||
367 | /* Set bits in SP_BYTES bitmap for bytes relative to sp + min_sp_off | |
368 | which contain arguments. Checking has been done in the previous | |
369 | loop. */ | |
370 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
371 | if (GET_CODE (XEXP (p, 0)) == USE | |
372 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
373 | { | |
374 | rtx mem = XEXP (XEXP (p, 0), 0), addr; | |
d05d7551 RS |
375 | HOST_WIDE_INT off = 0, byte, size; |
376 | /* Checked in the previous iteration. */ | |
377 | size = MEM_SIZE (mem).to_constant (); | |
0196c95e JJ |
378 | addr = XEXP (mem, 0); |
379 | if (GET_CODE (addr) == PLUS | |
380 | && REG_P (XEXP (addr, 0)) | |
381 | && CONST_INT_P (XEXP (addr, 1))) | |
382 | { | |
383 | off = INTVAL (XEXP (addr, 1)); | |
384 | addr = XEXP (addr, 0); | |
385 | } | |
386 | if (addr != stack_pointer_rtx) | |
387 | { | |
bfac633a | 388 | df_ref use; |
0196c95e JJ |
389 | struct df_link *defs; |
390 | rtx set; | |
391 | ||
bfac633a RS |
392 | FOR_EACH_INSN_USE (use, call_insn) |
393 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
394 | break; |
395 | ||
bfac633a | 396 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
397 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
398 | break; | |
399 | ||
400 | set = single_set (DF_REF_INSN (defs->ref)); | |
401 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
402 | } | |
d05d7551 | 403 | for (byte = off; byte < off + size; byte++) |
0196c95e | 404 | { |
821bb7f8 RG |
405 | if (!bitmap_set_bit (sp_bytes, byte - min_sp_off)) |
406 | gcc_unreachable (); | |
0196c95e JJ |
407 | } |
408 | } | |
409 | ||
410 | /* Walk backwards, looking for argument stores. The search stops | |
750900db | 411 | when seeing another call, sp adjustment or memory store other than |
0196c95e JJ |
412 | argument store. */ |
413 | ret = false; | |
414 | for (insn = PREV_INSN (call_insn); insn; insn = prev_insn) | |
415 | { | |
416 | rtx set, mem, addr; | |
2e0642cd | 417 | HOST_WIDE_INT off; |
0196c95e JJ |
418 | |
419 | if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn))) | |
0ece9321 | 420 | prev_insn = NULL; |
0196c95e JJ |
421 | else |
422 | prev_insn = PREV_INSN (insn); | |
423 | ||
424 | if (CALL_P (insn)) | |
425 | break; | |
426 | ||
2e0642cd | 427 | if (!NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
428 | continue; |
429 | ||
430 | set = single_set (insn); | |
431 | if (!set || SET_DEST (set) == stack_pointer_rtx) | |
432 | break; | |
433 | ||
434 | if (!MEM_P (SET_DEST (set))) | |
435 | continue; | |
436 | ||
437 | mem = SET_DEST (set); | |
438 | addr = XEXP (mem, 0); | |
439 | off = 0; | |
440 | if (GET_CODE (addr) == PLUS | |
441 | && REG_P (XEXP (addr, 0)) | |
442 | && CONST_INT_P (XEXP (addr, 1))) | |
443 | { | |
444 | off = INTVAL (XEXP (addr, 1)); | |
445 | addr = XEXP (addr, 0); | |
446 | } | |
447 | if (addr != stack_pointer_rtx) | |
448 | { | |
449 | if (!REG_P (addr)) | |
450 | break; | |
451 | if (!fast) | |
452 | { | |
bfac633a | 453 | df_ref use; |
0196c95e JJ |
454 | struct df_link *defs; |
455 | rtx set; | |
456 | ||
bfac633a RS |
457 | FOR_EACH_INSN_USE (use, insn) |
458 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
0196c95e JJ |
459 | break; |
460 | ||
bfac633a | 461 | if (use == NULL) |
0196c95e JJ |
462 | break; |
463 | ||
bfac633a | 464 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
0196c95e JJ |
465 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
466 | break; | |
467 | ||
468 | if (defs == NULL) | |
469 | break; | |
470 | ||
471 | set = single_set (DF_REF_INSN (defs->ref)); | |
472 | if (!set) | |
473 | break; | |
474 | ||
475 | if (GET_CODE (SET_SRC (set)) != PLUS | |
476 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
477 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
478 | break; | |
479 | ||
480 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
481 | } | |
482 | else | |
483 | break; | |
484 | } | |
485 | ||
d05d7551 | 486 | HOST_WIDE_INT size; |
7eb87420 | 487 | if (!MEM_SIZE_KNOWN_P (mem) |
d05d7551 RS |
488 | || !MEM_SIZE (mem).is_constant (&size) |
489 | || !check_argument_store (size, off, min_sp_off, | |
2e0642cd | 490 | max_sp_off, sp_bytes)) |
0196c95e JJ |
491 | break; |
492 | ||
0196c95e JJ |
493 | if (!deletable_insn_p (insn, fast, NULL)) |
494 | break; | |
495 | ||
496 | if (do_mark) | |
497 | mark_insn (insn, fast); | |
498 | else | |
499 | bitmap_set_bit (arg_stores, INSN_UID (insn)); | |
500 | ||
501 | if (bitmap_empty_p (sp_bytes)) | |
502 | { | |
503 | ret = true; | |
504 | break; | |
505 | } | |
506 | } | |
507 | ||
508 | BITMAP_FREE (sp_bytes); | |
509 | if (!ret && arg_stores) | |
510 | bitmap_clear (arg_stores); | |
511 | ||
512 | return ret; | |
513 | } | |
514 | ||
515 | ||
885c9b5d EB |
516 | /* Remove all REG_EQUAL and REG_EQUIV notes referring to the registers INSN |
517 | writes to. */ | |
6fb5fa3c DB |
518 | |
519 | static void | |
0ece9321 | 520 | remove_reg_equal_equiv_notes_for_defs (rtx_insn *insn) |
6fb5fa3c | 521 | { |
bfac633a | 522 | df_ref def; |
885c9b5d | 523 | |
bfac633a RS |
524 | FOR_EACH_INSN_DEF (def, insn) |
525 | remove_reg_equal_equiv_notes_for_regno (DF_REF_REGNO (def)); | |
6fb5fa3c DB |
526 | } |
527 | ||
a7a110bb AO |
528 | /* Scan all BBs for debug insns and reset those that reference values |
529 | defined in unmarked insns. */ | |
530 | ||
531 | static void | |
532 | reset_unmarked_insns_debug_uses (void) | |
533 | { | |
534 | basic_block bb; | |
0ece9321 | 535 | rtx_insn *insn, *next; |
a7a110bb | 536 | |
4f42035e | 537 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
a7a110bb AO |
538 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
539 | if (DEBUG_INSN_P (insn)) | |
540 | { | |
bfac633a | 541 | df_ref use; |
a7a110bb | 542 | |
bfac633a | 543 | FOR_EACH_INSN_USE (use, insn) |
a7a110bb | 544 | { |
a7a110bb AO |
545 | struct df_link *defs; |
546 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
547 | { | |
0ece9321 | 548 | rtx_insn *ref_insn; |
a7a110bb AO |
549 | if (DF_REF_IS_ARTIFICIAL (defs->ref)) |
550 | continue; | |
8ced31fe JJ |
551 | ref_insn = DF_REF_INSN (defs->ref); |
552 | if (!marked_insn_p (ref_insn)) | |
a7a110bb AO |
553 | break; |
554 | } | |
555 | if (!defs) | |
556 | continue; | |
557 | /* ??? FIXME could we propagate the values assigned to | |
558 | each of the DEFs? */ | |
559 | INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC (); | |
560 | df_insn_rescan_debug_internal (insn); | |
8ced31fe | 561 | break; |
a7a110bb AO |
562 | } |
563 | } | |
564 | } | |
6fb5fa3c | 565 | |
9ed7b221 | 566 | /* Delete every instruction that hasn't been marked. */ |
6fb5fa3c DB |
567 | |
568 | static void | |
569 | delete_unmarked_insns (void) | |
570 | { | |
571 | basic_block bb; | |
0ece9321 | 572 | rtx_insn *insn, *next; |
5ba5ab9b | 573 | bool must_clean = false; |
6fb5fa3c | 574 | |
4f42035e | 575 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
cd3f1729 | 576 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
a7a110bb | 577 | if (NONDEBUG_INSN_P (insn)) |
6fb5fa3c | 578 | { |
6f21dc3c JJ |
579 | rtx turn_into_use = NULL_RTX; |
580 | ||
9ed7b221 | 581 | /* Always delete no-op moves. */ |
6fb5fa3c | 582 | if (noop_move_p (insn)) |
6f21dc3c JJ |
583 | { |
584 | if (RTX_FRAME_RELATED_P (insn)) | |
585 | turn_into_use | |
586 | = find_reg_note (insn, REG_CFA_RESTORE, NULL); | |
587 | if (turn_into_use && REG_P (XEXP (turn_into_use, 0))) | |
588 | turn_into_use = XEXP (turn_into_use, 0); | |
589 | else | |
590 | turn_into_use = NULL_RTX; | |
591 | } | |
9ed7b221 | 592 | |
9ed7b221 | 593 | /* Otherwise rely only on the DCE algorithm. */ |
6fb5fa3c DB |
594 | else if (marked_insn_p (insn)) |
595 | continue; | |
596 | ||
cd3f1729 KZ |
597 | /* Beware that reaching a dbg counter limit here can result |
598 | in miscompiled file. This occurs when a group of insns | |
599 | must be deleted together, typically because the kept insn | |
600 | depends on the output from the deleted insn. Deleting | |
601 | this insns in reverse order (both at the bb level and | |
602 | when looking at the blocks) minimizes this, but does not | |
603 | eliminate it, since it is possible for the using insn to | |
604 | be top of a block and the producer to be at the bottom of | |
605 | the block. However, in most cases this will only result | |
606 | in an uninitialized use of an insn that is dead anyway. | |
607 | ||
608 | However, there is one rare case that will cause a | |
609 | miscompile: deletion of non-looping pure and constant | |
610 | calls on a machine where ACCUMULATE_OUTGOING_ARGS is true. | |
611 | In this case it is possible to remove the call, but leave | |
612 | the argument pushes to the stack. Because of the changes | |
613 | to the stack pointer, this will almost always lead to a | |
614 | miscompile. */ | |
6fb5fa3c DB |
615 | if (!dbg_cnt (dce)) |
616 | continue; | |
617 | ||
618 | if (dump_file) | |
619 | fprintf (dump_file, "DCE: Deleting insn %d\n", INSN_UID (insn)); | |
620 | ||
885c9b5d | 621 | /* Before we delete the insn we have to remove the REG_EQUAL notes |
9ed7b221 | 622 | for the destination regs in order to avoid dangling notes. */ |
885c9b5d | 623 | remove_reg_equal_equiv_notes_for_defs (insn); |
6fb5fa3c | 624 | |
5ba5ab9b KZ |
625 | /* If a pure or const call is deleted, this may make the cfg |
626 | have unreachable blocks. We rememeber this and call | |
627 | delete_unreachable_blocks at the end. */ | |
628 | if (CALL_P (insn)) | |
629 | must_clean = true; | |
630 | ||
6f21dc3c JJ |
631 | if (turn_into_use) |
632 | { | |
633 | /* Don't remove frame related noop moves if they cary | |
634 | REG_CFA_RESTORE note, while we don't need to emit any code, | |
635 | we need it to emit the CFI restore note. */ | |
636 | PATTERN (insn) | |
637 | = gen_rtx_USE (GET_MODE (turn_into_use), turn_into_use); | |
638 | INSN_CODE (insn) = -1; | |
639 | df_insn_rescan (insn); | |
640 | } | |
641 | else | |
642 | /* Now delete the insn. */ | |
643 | delete_insn_and_edges (insn); | |
6fb5fa3c | 644 | } |
5ba5ab9b KZ |
645 | |
646 | /* Deleted a pure or const call. */ | |
647 | if (must_clean) | |
648 | delete_unreachable_blocks (); | |
6fb5fa3c DB |
649 | } |
650 | ||
651 | ||
6fb5fa3c DB |
652 | /* Go through the instructions and mark those whose necessity is not |
653 | dependent on inter-instruction information. Make sure all other | |
654 | instructions are not marked. */ | |
655 | ||
656 | static void | |
657 | prescan_insns_for_dce (bool fast) | |
658 | { | |
659 | basic_block bb; | |
0ece9321 | 660 | rtx_insn *insn, *prev; |
0196c95e JJ |
661 | bitmap arg_stores = NULL; |
662 | ||
6fb5fa3c DB |
663 | if (dump_file) |
664 | fprintf (dump_file, "Finding needed instructions:\n"); | |
0196c95e JJ |
665 | |
666 | if (!df_in_progress && ACCUMULATE_OUTGOING_ARGS) | |
667 | arg_stores = BITMAP_ALLOC (NULL); | |
668 | ||
11cd3bed | 669 | FOR_EACH_BB_FN (bb, cfun) |
0196c95e JJ |
670 | { |
671 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev) | |
a7a110bb | 672 | if (NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
673 | { |
674 | /* Don't mark argument stores now. They will be marked | |
675 | if needed when the associated CALL is marked. */ | |
676 | if (arg_stores && bitmap_bit_p (arg_stores, INSN_UID (insn))) | |
677 | continue; | |
678 | if (deletable_insn_p (insn, fast, arg_stores)) | |
679 | mark_nonreg_stores (PATTERN (insn), insn, fast); | |
680 | else | |
681 | mark_insn (insn, fast); | |
682 | } | |
683 | /* find_call_stack_args only looks at argument stores in the | |
684 | same bb. */ | |
685 | if (arg_stores) | |
686 | bitmap_clear (arg_stores); | |
687 | } | |
688 | ||
689 | if (arg_stores) | |
690 | BITMAP_FREE (arg_stores); | |
6fb5fa3c DB |
691 | |
692 | if (dump_file) | |
693 | fprintf (dump_file, "Finished finding needed instructions:\n"); | |
694 | } | |
695 | ||
696 | ||
697 | /* UD-based DSE routines. */ | |
698 | ||
6ed3da00 | 699 | /* Mark instructions that define artificially-used registers, such as |
6fb5fa3c DB |
700 | the frame pointer and the stack pointer. */ |
701 | ||
702 | static void | |
703 | mark_artificial_uses (void) | |
704 | { | |
705 | basic_block bb; | |
706 | struct df_link *defs; | |
292321a5 | 707 | df_ref use; |
6fb5fa3c | 708 | |
04a90bec | 709 | FOR_ALL_BB_FN (bb, cfun) |
292321a5 RS |
710 | FOR_EACH_ARTIFICIAL_USE (use, bb->index) |
711 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
712 | if (!DF_REF_IS_ARTIFICIAL (defs->ref)) | |
713 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
714 | } |
715 | ||
2e6be65e | 716 | |
6fb5fa3c DB |
717 | /* Mark every instruction that defines a register value that INSN uses. */ |
718 | ||
719 | static void | |
0ece9321 | 720 | mark_reg_dependencies (rtx_insn *insn) |
6fb5fa3c DB |
721 | { |
722 | struct df_link *defs; | |
bfac633a | 723 | df_ref use; |
6fb5fa3c | 724 | |
b5b8b0ac AO |
725 | if (DEBUG_INSN_P (insn)) |
726 | return; | |
727 | ||
bfac633a | 728 | FOR_EACH_INSN_USE (use, insn) |
6fb5fa3c | 729 | { |
6fb5fa3c DB |
730 | if (dump_file) |
731 | { | |
732 | fprintf (dump_file, "Processing use of "); | |
733 | print_simple_rtl (dump_file, DF_REF_REG (use)); | |
734 | fprintf (dump_file, " in insn %d:\n", INSN_UID (insn)); | |
735 | } | |
736 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
50e94c7e SB |
737 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
738 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
739 | } |
740 | } | |
741 | ||
742 | ||
2e6be65e EB |
743 | /* Initialize global variables for a new DCE pass. */ |
744 | ||
6fb5fa3c | 745 | static void |
2e6be65e EB |
746 | init_dce (bool fast) |
747 | { | |
748 | if (!df_in_progress) | |
749 | { | |
750 | if (!fast) | |
7b19209f SB |
751 | { |
752 | df_set_flags (DF_RD_PRUNE_DEAD_DEFS); | |
753 | df_chain_add_problem (DF_UD_CHAIN); | |
754 | } | |
2e6be65e EB |
755 | df_analyze (); |
756 | } | |
757 | ||
758 | if (dump_file) | |
759 | df_dump (dump_file); | |
760 | ||
761 | if (fast) | |
762 | { | |
763 | bitmap_obstack_initialize (&dce_blocks_bitmap_obstack); | |
764 | bitmap_obstack_initialize (&dce_tmp_bitmap_obstack); | |
2da02156 | 765 | can_alter_cfg = false; |
2e6be65e | 766 | } |
2da02156 EB |
767 | else |
768 | can_alter_cfg = true; | |
2e6be65e EB |
769 | |
770 | marked = sbitmap_alloc (get_max_uid () + 1); | |
f61e445a | 771 | bitmap_clear (marked); |
2e6be65e EB |
772 | } |
773 | ||
774 | ||
775 | /* Free the data allocated by init_dce. */ | |
776 | ||
777 | static void | |
778 | fini_dce (bool fast) | |
6fb5fa3c DB |
779 | { |
780 | sbitmap_free (marked); | |
2e6be65e EB |
781 | |
782 | if (fast) | |
783 | { | |
784 | bitmap_obstack_release (&dce_blocks_bitmap_obstack); | |
785 | bitmap_obstack_release (&dce_tmp_bitmap_obstack); | |
786 | } | |
6fb5fa3c DB |
787 | } |
788 | ||
789 | ||
790 | /* UD-chain based DCE. */ | |
791 | ||
792 | static unsigned int | |
793 | rest_of_handle_ud_dce (void) | |
794 | { | |
0ece9321 | 795 | rtx_insn *insn; |
6fb5fa3c | 796 | |
6fb5fa3c DB |
797 | init_dce (false); |
798 | ||
799 | prescan_insns_for_dce (false); | |
800 | mark_artificial_uses (); | |
9771b263 | 801 | while (worklist.length () > 0) |
6fb5fa3c | 802 | { |
9771b263 | 803 | insn = worklist.pop (); |
6fb5fa3c DB |
804 | mark_reg_dependencies (insn); |
805 | } | |
9771b263 | 806 | worklist.release (); |
2e6be65e | 807 | |
36f52e8f | 808 | if (MAY_HAVE_DEBUG_BIND_INSNS) |
a7a110bb AO |
809 | reset_unmarked_insns_debug_uses (); |
810 | ||
6fb5fa3c DB |
811 | /* Before any insns are deleted, we must remove the chains since |
812 | they are not bidirectional. */ | |
813 | df_remove_problem (df_chain); | |
814 | delete_unmarked_insns (); | |
815 | ||
2e6be65e | 816 | fini_dce (false); |
6fb5fa3c DB |
817 | return 0; |
818 | } | |
819 | ||
820 | ||
17795822 TS |
821 | namespace { |
822 | ||
823 | const pass_data pass_data_ud_rtl_dce = | |
6fb5fa3c | 824 | { |
27a4cd48 DM |
825 | RTL_PASS, /* type */ |
826 | "ud_dce", /* name */ | |
827 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
828 | TV_DCE, /* tv_id */ |
829 | 0, /* properties_required */ | |
830 | 0, /* properties_provided */ | |
831 | 0, /* properties_destroyed */ | |
832 | 0, /* todo_flags_start */ | |
3bea341f | 833 | TODO_df_finish, /* todo_flags_finish */ |
6fb5fa3c DB |
834 | }; |
835 | ||
17795822 | 836 | class pass_ud_rtl_dce : public rtl_opt_pass |
27a4cd48 DM |
837 | { |
838 | public: | |
c3284718 RS |
839 | pass_ud_rtl_dce (gcc::context *ctxt) |
840 | : rtl_opt_pass (pass_data_ud_rtl_dce, ctxt) | |
27a4cd48 DM |
841 | {} |
842 | ||
843 | /* opt_pass methods: */ | |
1a3d085c TS |
844 | virtual bool gate (function *) |
845 | { | |
846 | return optimize > 1 && flag_dce && dbg_cnt (dce_ud); | |
847 | } | |
848 | ||
be55bfe6 TS |
849 | virtual unsigned int execute (function *) |
850 | { | |
851 | return rest_of_handle_ud_dce (); | |
852 | } | |
27a4cd48 DM |
853 | |
854 | }; // class pass_ud_rtl_dce | |
855 | ||
17795822 TS |
856 | } // anon namespace |
857 | ||
27a4cd48 DM |
858 | rtl_opt_pass * |
859 | make_pass_ud_rtl_dce (gcc::context *ctxt) | |
860 | { | |
861 | return new pass_ud_rtl_dce (ctxt); | |
862 | } | |
863 | ||
2e6be65e | 864 | |
6fb5fa3c DB |
865 | /* ------------------------------------------------------------------------- |
866 | Fast DCE functions | |
867 | ------------------------------------------------------------------------- */ | |
868 | ||
cc806ac1 RS |
869 | /* Process basic block BB. Return true if the live_in set has |
870 | changed. REDO_OUT is true if the info at the bottom of the block | |
871 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
872 | artificial uses. Track global substitution of uses of dead pseudos |
873 | in debug insns using GLOBAL_DEBUG. */ | |
6fb5fa3c DB |
874 | |
875 | static bool | |
e9f950ba AO |
876 | word_dce_process_block (basic_block bb, bool redo_out, |
877 | struct dead_debug_global *global_debug) | |
6fb5fa3c DB |
878 | { |
879 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
0ece9321 | 880 | rtx_insn *insn; |
6fb5fa3c | 881 | bool block_changed; |
e9f950ba | 882 | struct dead_debug_local debug; |
6fb5fa3c DB |
883 | |
884 | if (redo_out) | |
885 | { | |
886 | /* Need to redo the live_out set of this block if when one of | |
887 | the succs of this block has had a change in it live in | |
888 | set. */ | |
889 | edge e; | |
890 | edge_iterator ei; | |
8d074192 BS |
891 | df_confluence_function_n con_fun_n = df_word_lr->problem->con_fun_n; |
892 | bitmap_clear (DF_WORD_LR_OUT (bb)); | |
6fb5fa3c DB |
893 | FOR_EACH_EDGE (e, ei, bb->succs) |
894 | (*con_fun_n) (e); | |
895 | } | |
896 | ||
897 | if (dump_file) | |
898 | { | |
899 | fprintf (dump_file, "processing block %d live out = ", bb->index); | |
8d074192 | 900 | df_print_word_regset (dump_file, DF_WORD_LR_OUT (bb)); |
6fb5fa3c DB |
901 | } |
902 | ||
8d074192 | 903 | bitmap_copy (local_live, DF_WORD_LR_OUT (bb)); |
e9f950ba | 904 | dead_debug_local_init (&debug, NULL, global_debug); |
cc806ac1 RS |
905 | |
906 | FOR_BB_INSNS_REVERSE (bb, insn) | |
1adbb361 AO |
907 | if (DEBUG_INSN_P (insn)) |
908 | { | |
bfac633a RS |
909 | df_ref use; |
910 | FOR_EACH_INSN_USE (use, insn) | |
911 | if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER | |
cf098191 RS |
912 | && known_eq (GET_MODE_SIZE (GET_MODE (DF_REF_REAL_REG (use))), |
913 | 2 * UNITS_PER_WORD) | |
bfac633a RS |
914 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use)) |
915 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use) + 1)) | |
916 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
1adbb361 AO |
917 | } |
918 | else if (INSN_P (insn)) | |
cc806ac1 | 919 | { |
8d074192 | 920 | bool any_changed; |
1adbb361 | 921 | |
cc806ac1 RS |
922 | /* No matter if the instruction is needed or not, we remove |
923 | any regno in the defs from the live set. */ | |
8d074192 BS |
924 | any_changed = df_word_lr_simulate_defs (insn, local_live); |
925 | if (any_changed) | |
926 | mark_insn (insn, true); | |
cc806ac1 RS |
927 | |
928 | /* On the other hand, we do not allow the dead uses to set | |
929 | anything in local_live. */ | |
930 | if (marked_insn_p (insn)) | |
8d074192 | 931 | df_word_lr_simulate_uses (insn, local_live); |
6f9e260c | 932 | |
39bc0f01 | 933 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
934 | insns. We may have to emit a debug temp even if the insn |
935 | was marked, in case the debug use was after the point of | |
936 | death. */ | |
937 | if (debug.used && !bitmap_empty_p (debug.used)) | |
1adbb361 | 938 | { |
bfac633a | 939 | df_ref def; |
1adbb361 | 940 | |
bfac633a RS |
941 | FOR_EACH_INSN_DEF (def, insn) |
942 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
85d87497 JJ |
943 | marked_insn_p (insn) |
944 | && !control_flow_insn_p (insn) | |
945 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
946 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
1adbb361 AO |
947 | } |
948 | ||
cc806ac1 RS |
949 | if (dump_file) |
950 | { | |
b8698a0f | 951 | fprintf (dump_file, "finished processing insn %d live out = ", |
cc806ac1 | 952 | INSN_UID (insn)); |
8d074192 | 953 | df_print_word_regset (dump_file, local_live); |
cc806ac1 RS |
954 | } |
955 | } | |
b8698a0f | 956 | |
8d074192 | 957 | block_changed = !bitmap_equal_p (local_live, DF_WORD_LR_IN (bb)); |
cc806ac1 | 958 | if (block_changed) |
8d074192 BS |
959 | bitmap_copy (DF_WORD_LR_IN (bb), local_live); |
960 | ||
e9f950ba | 961 | dead_debug_local_finish (&debug, NULL); |
cc806ac1 RS |
962 | BITMAP_FREE (local_live); |
963 | return block_changed; | |
964 | } | |
965 | ||
966 | ||
967 | /* Process basic block BB. Return true if the live_in set has | |
968 | changed. REDO_OUT is true if the info at the bottom of the block | |
969 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
970 | artificial uses. Track global substitution of uses of dead pseudos |
971 | in debug insns using GLOBAL_DEBUG. */ | |
cc806ac1 RS |
972 | |
973 | static bool | |
e9f950ba AO |
974 | dce_process_block (basic_block bb, bool redo_out, bitmap au, |
975 | struct dead_debug_global *global_debug) | |
cc806ac1 RS |
976 | { |
977 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
0ece9321 | 978 | rtx_insn *insn; |
cc806ac1 | 979 | bool block_changed; |
bfac633a | 980 | df_ref def; |
e9f950ba | 981 | struct dead_debug_local debug; |
6fb5fa3c | 982 | |
cc806ac1 | 983 | if (redo_out) |
6fb5fa3c | 984 | { |
cc806ac1 RS |
985 | /* Need to redo the live_out set of this block if when one of |
986 | the succs of this block has had a change in it live in | |
987 | set. */ | |
988 | edge e; | |
989 | edge_iterator ei; | |
990 | df_confluence_function_n con_fun_n = df_lr->problem->con_fun_n; | |
991 | bitmap_clear (DF_LR_OUT (bb)); | |
992 | FOR_EACH_EDGE (e, ei, bb->succs) | |
993 | (*con_fun_n) (e); | |
6fb5fa3c DB |
994 | } |
995 | ||
cc806ac1 | 996 | if (dump_file) |
6fb5fa3c | 997 | { |
fafe34f9 | 998 | fprintf (dump_file, "processing block %d lr out = ", bb->index); |
cc806ac1 | 999 | df_print_regset (dump_file, DF_LR_OUT (bb)); |
6fb5fa3c DB |
1000 | } |
1001 | ||
cc806ac1 RS |
1002 | bitmap_copy (local_live, DF_LR_OUT (bb)); |
1003 | ||
02b47899 | 1004 | df_simulate_initialize_backwards (bb, local_live); |
e9f950ba | 1005 | dead_debug_local_init (&debug, NULL, global_debug); |
541d3103 | 1006 | |
6fb5fa3c | 1007 | FOR_BB_INSNS_REVERSE (bb, insn) |
1adbb361 AO |
1008 | if (DEBUG_INSN_P (insn)) |
1009 | { | |
bfac633a RS |
1010 | df_ref use; |
1011 | FOR_EACH_INSN_USE (use, insn) | |
1012 | if (!bitmap_bit_p (local_live, DF_REF_REGNO (use)) | |
1013 | && !bitmap_bit_p (au, DF_REF_REGNO (use))) | |
1014 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
1adbb361 AO |
1015 | } |
1016 | else if (INSN_P (insn)) | |
6fb5fa3c | 1017 | { |
f251709a | 1018 | bool needed = marked_insn_p (insn); |
9ed7b221 EB |
1019 | |
1020 | /* The insn is needed if there is someone who uses the output. */ | |
f251709a | 1021 | if (!needed) |
bfac633a RS |
1022 | FOR_EACH_INSN_DEF (def, insn) |
1023 | if (bitmap_bit_p (local_live, DF_REF_REGNO (def)) | |
1024 | || bitmap_bit_p (au, DF_REF_REGNO (def))) | |
39bc0f01 AO |
1025 | { |
1026 | needed = true; | |
1027 | mark_insn (insn, true); | |
1028 | break; | |
1029 | } | |
b8698a0f | 1030 | |
6fb5fa3c DB |
1031 | /* No matter if the instruction is needed or not, we remove |
1032 | any regno in the defs from the live set. */ | |
1033 | df_simulate_defs (insn, local_live); | |
1034 | ||
1035 | /* On the other hand, we do not allow the dead uses to set | |
1036 | anything in local_live. */ | |
f251709a | 1037 | if (needed) |
6fb5fa3c | 1038 | df_simulate_uses (insn, local_live); |
6f9e260c | 1039 | |
39bc0f01 | 1040 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
1041 | insns. We may have to emit a debug temp even if the insn |
1042 | was marked, in case the debug use was after the point of | |
1043 | death. */ | |
1044 | if (debug.used && !bitmap_empty_p (debug.used)) | |
bfac633a RS |
1045 | FOR_EACH_INSN_DEF (def, insn) |
1046 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
85d87497 JJ |
1047 | needed && !control_flow_insn_p (insn) |
1048 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
1049 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
6fb5fa3c | 1050 | } |
b8698a0f | 1051 | |
e9f950ba | 1052 | dead_debug_local_finish (&debug, NULL); |
02b47899 | 1053 | df_simulate_finalize_backwards (bb, local_live); |
6fb5fa3c DB |
1054 | |
1055 | block_changed = !bitmap_equal_p (local_live, DF_LR_IN (bb)); | |
1056 | if (block_changed) | |
1057 | bitmap_copy (DF_LR_IN (bb), local_live); | |
1058 | ||
1059 | BITMAP_FREE (local_live); | |
1060 | return block_changed; | |
1061 | } | |
1062 | ||
2e6be65e | 1063 | |
8d074192 BS |
1064 | /* Perform fast DCE once initialization is done. If WORD_LEVEL is |
1065 | true, use the word level dce, otherwise do it at the pseudo | |
cc806ac1 | 1066 | level. */ |
2e6be65e | 1067 | |
6fb5fa3c | 1068 | static void |
8d074192 | 1069 | fast_dce (bool word_level) |
6fb5fa3c DB |
1070 | { |
1071 | int *postorder = df_get_postorder (DF_BACKWARD); | |
1072 | int n_blocks = df_get_n_blocks (DF_BACKWARD); | |
6fb5fa3c DB |
1073 | /* The set of blocks that have been seen on this iteration. */ |
1074 | bitmap processed = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1075 | /* The set of blocks that need to have the out vectors reset because | |
1076 | the in of one of their successors has changed. */ | |
1077 | bitmap redo_out = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1078 | bitmap all_blocks = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1079 | bool global_changed = true; | |
cc806ac1 RS |
1080 | |
1081 | /* These regs are considered always live so if they end up dying | |
1082 | because of some def, we need to bring the back again. Calling | |
1083 | df_simulate_fixup_sets has the disadvantage of calling | |
1084 | bb_has_eh_pred once per insn, so we cache the information | |
1085 | here. */ | |
a7e3698d JH |
1086 | bitmap au = &df->regular_block_artificial_uses; |
1087 | bitmap au_eh = &df->eh_block_artificial_uses; | |
9ed7b221 | 1088 | int i; |
e9f950ba | 1089 | struct dead_debug_global global_debug; |
6fb5fa3c DB |
1090 | |
1091 | prescan_insns_for_dce (true); | |
1092 | ||
1093 | for (i = 0; i < n_blocks; i++) | |
1094 | bitmap_set_bit (all_blocks, postorder[i]); | |
1095 | ||
e9f950ba AO |
1096 | dead_debug_global_init (&global_debug, NULL); |
1097 | ||
6fb5fa3c DB |
1098 | while (global_changed) |
1099 | { | |
1100 | global_changed = false; | |
9ed7b221 | 1101 | |
6fb5fa3c DB |
1102 | for (i = 0; i < n_blocks; i++) |
1103 | { | |
1104 | int index = postorder[i]; | |
06e28de2 | 1105 | basic_block bb = BASIC_BLOCK_FOR_FN (cfun, index); |
6fb5fa3c DB |
1106 | bool local_changed; |
1107 | ||
1108 | if (index < NUM_FIXED_BLOCKS) | |
1109 | { | |
1110 | bitmap_set_bit (processed, index); | |
1111 | continue; | |
1112 | } | |
1113 | ||
8d074192 | 1114 | if (word_level) |
b8698a0f | 1115 | local_changed |
e9f950ba AO |
1116 | = word_dce_process_block (bb, bitmap_bit_p (redo_out, index), |
1117 | &global_debug); | |
cc806ac1 | 1118 | else |
b8698a0f | 1119 | local_changed |
cc806ac1 | 1120 | = dce_process_block (bb, bitmap_bit_p (redo_out, index), |
e9f950ba AO |
1121 | bb_has_eh_pred (bb) ? au_eh : au, |
1122 | &global_debug); | |
6fb5fa3c | 1123 | bitmap_set_bit (processed, index); |
b8698a0f | 1124 | |
6fb5fa3c DB |
1125 | if (local_changed) |
1126 | { | |
1127 | edge e; | |
1128 | edge_iterator ei; | |
1129 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1130 | if (bitmap_bit_p (processed, e->src->index)) | |
1131 | /* Be tricky about when we need to iterate the | |
1132 | analysis. We only have redo the analysis if the | |
1133 | bitmaps change at the top of a block that is the | |
1134 | entry to a loop. */ | |
1135 | global_changed = true; | |
1136 | else | |
1137 | bitmap_set_bit (redo_out, e->src->index); | |
1138 | } | |
1139 | } | |
b8698a0f | 1140 | |
6fb5fa3c DB |
1141 | if (global_changed) |
1142 | { | |
1143 | /* Turn off the RUN_DCE flag to prevent recursive calls to | |
1144 | dce. */ | |
1145 | int old_flag = df_clear_flags (DF_LR_RUN_DCE); | |
1146 | ||
1147 | /* So something was deleted that requires a redo. Do it on | |
1148 | the cheap. */ | |
1149 | delete_unmarked_insns (); | |
f61e445a | 1150 | bitmap_clear (marked); |
6fb5fa3c DB |
1151 | bitmap_clear (processed); |
1152 | bitmap_clear (redo_out); | |
b8698a0f | 1153 | |
6fb5fa3c DB |
1154 | /* We do not need to rescan any instructions. We only need |
1155 | to redo the dataflow equations for the blocks that had a | |
1156 | change at the top of the block. Then we need to redo the | |
b8698a0f | 1157 | iteration. */ |
8d074192 BS |
1158 | if (word_level) |
1159 | df_analyze_problem (df_word_lr, all_blocks, postorder, n_blocks); | |
cc806ac1 RS |
1160 | else |
1161 | df_analyze_problem (df_lr, all_blocks, postorder, n_blocks); | |
6fb5fa3c DB |
1162 | |
1163 | if (old_flag & DF_LR_RUN_DCE) | |
1164 | df_set_flags (DF_LR_RUN_DCE); | |
9ed7b221 | 1165 | |
6fb5fa3c DB |
1166 | prescan_insns_for_dce (true); |
1167 | } | |
6fb5fa3c DB |
1168 | } |
1169 | ||
e9f950ba AO |
1170 | dead_debug_global_finish (&global_debug, NULL); |
1171 | ||
6fb5fa3c DB |
1172 | delete_unmarked_insns (); |
1173 | ||
1174 | BITMAP_FREE (processed); | |
1175 | BITMAP_FREE (redo_out); | |
1176 | BITMAP_FREE (all_blocks); | |
1177 | } | |
1178 | ||
1179 | ||
cc806ac1 | 1180 | /* Fast register level DCE. */ |
6fb5fa3c DB |
1181 | |
1182 | static unsigned int | |
1183 | rest_of_handle_fast_dce (void) | |
1184 | { | |
1185 | init_dce (true); | |
cc806ac1 RS |
1186 | fast_dce (false); |
1187 | fini_dce (true); | |
1188 | return 0; | |
1189 | } | |
1190 | ||
1191 | ||
1192 | /* Fast byte level DCE. */ | |
1193 | ||
8d074192 BS |
1194 | void |
1195 | run_word_dce (void) | |
cc806ac1 | 1196 | { |
25aef556 BS |
1197 | int old_flags; |
1198 | ||
1199 | if (!flag_dce) | |
1200 | return; | |
1201 | ||
8d074192 | 1202 | timevar_push (TV_DCE); |
25aef556 | 1203 | old_flags = df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
8d074192 | 1204 | df_word_lr_add_problem (); |
cc806ac1 RS |
1205 | init_dce (true); |
1206 | fast_dce (true); | |
2e6be65e | 1207 | fini_dce (true); |
25aef556 | 1208 | df_set_flags (old_flags); |
8d074192 | 1209 | timevar_pop (TV_DCE); |
6fb5fa3c DB |
1210 | } |
1211 | ||
1212 | ||
1213 | /* This is an internal call that is used by the df live register | |
1214 | problem to run fast dce as a side effect of creating the live | |
1215 | information. The stack is organized so that the lr problem is run, | |
1216 | this pass is run, which updates the live info and the df scanning | |
1217 | info, and then returns to allow the rest of the problems to be run. | |
1218 | ||
1219 | This can be called by elsewhere but it will not update the bit | |
2e6be65e | 1220 | vectors for any other problems than LR. */ |
6fb5fa3c DB |
1221 | |
1222 | void | |
1223 | run_fast_df_dce (void) | |
1224 | { | |
1225 | if (flag_dce) | |
1226 | { | |
1227 | /* If dce is able to delete something, it has to happen | |
1228 | immediately. Otherwise there will be problems handling the | |
1229 | eq_notes. */ | |
81f40b79 ILT |
1230 | int old_flags = |
1231 | df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); | |
1232 | ||
6fb5fa3c DB |
1233 | df_in_progress = true; |
1234 | rest_of_handle_fast_dce (); | |
2e6be65e EB |
1235 | df_in_progress = false; |
1236 | ||
6fb5fa3c DB |
1237 | df_set_flags (old_flags); |
1238 | } | |
1239 | } | |
1240 | ||
2e6be65e | 1241 | |
9ed7b221 EB |
1242 | /* Run a fast DCE pass. */ |
1243 | ||
1244 | void | |
1245 | run_fast_dce (void) | |
6fb5fa3c | 1246 | { |
9ed7b221 EB |
1247 | if (flag_dce) |
1248 | rest_of_handle_fast_dce (); | |
6fb5fa3c DB |
1249 | } |
1250 | ||
1251 | ||
17795822 TS |
1252 | namespace { |
1253 | ||
1254 | const pass_data pass_data_fast_rtl_dce = | |
6fb5fa3c | 1255 | { |
27a4cd48 DM |
1256 | RTL_PASS, /* type */ |
1257 | "rtl_dce", /* name */ | |
1258 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
1259 | TV_DCE, /* tv_id */ |
1260 | 0, /* properties_required */ | |
1261 | 0, /* properties_provided */ | |
1262 | 0, /* properties_destroyed */ | |
1263 | 0, /* todo_flags_start */ | |
3bea341f | 1264 | TODO_df_finish, /* todo_flags_finish */ |
6fb5fa3c | 1265 | }; |
27a4cd48 | 1266 | |
17795822 | 1267 | class pass_fast_rtl_dce : public rtl_opt_pass |
27a4cd48 DM |
1268 | { |
1269 | public: | |
c3284718 RS |
1270 | pass_fast_rtl_dce (gcc::context *ctxt) |
1271 | : rtl_opt_pass (pass_data_fast_rtl_dce, ctxt) | |
27a4cd48 DM |
1272 | {} |
1273 | ||
1274 | /* opt_pass methods: */ | |
1a3d085c TS |
1275 | virtual bool gate (function *) |
1276 | { | |
1277 | return optimize > 0 && flag_dce && dbg_cnt (dce_fast); | |
1278 | } | |
1279 | ||
be55bfe6 TS |
1280 | virtual unsigned int execute (function *) |
1281 | { | |
1282 | return rest_of_handle_fast_dce (); | |
1283 | } | |
27a4cd48 DM |
1284 | |
1285 | }; // class pass_fast_rtl_dce | |
1286 | ||
17795822 TS |
1287 | } // anon namespace |
1288 | ||
27a4cd48 DM |
1289 | rtl_opt_pass * |
1290 | make_pass_fast_rtl_dce (gcc::context *ctxt) | |
1291 | { | |
1292 | return new pass_fast_rtl_dce (ctxt); | |
1293 | } |