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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" | |
76416d89 | 38 | #include "rtl-iter.h" |
6fb5fa3c | 39 | |
6fb5fa3c DB |
40 | |
41 | /* ------------------------------------------------------------------------- | |
42 | Core mark/delete routines | |
43 | ------------------------------------------------------------------------- */ | |
44 | ||
2e6be65e EB |
45 | /* True if we are invoked while the df engine is running; in this case, |
46 | we don't want to reenter it. */ | |
6fb5fa3c DB |
47 | static bool df_in_progress = false; |
48 | ||
2da02156 EB |
49 | /* True if we are allowed to alter the CFG in this pass. */ |
50 | static bool can_alter_cfg = false; | |
51 | ||
6fb5fa3c DB |
52 | /* Instructions that have been marked but whose dependencies have not |
53 | yet been processed. */ | |
0ece9321 | 54 | static vec<rtx_insn *> worklist; |
6fb5fa3c | 55 | |
2e6be65e EB |
56 | /* Bitmap of instructions marked as needed indexed by INSN_UID. */ |
57 | static sbitmap marked; | |
58 | ||
59 | /* Bitmap obstacks used for block processing by the fast algorithm. */ | |
6fb5fa3c DB |
60 | static bitmap_obstack dce_blocks_bitmap_obstack; |
61 | static bitmap_obstack dce_tmp_bitmap_obstack; | |
62 | ||
0ece9321 | 63 | static bool find_call_stack_args (rtx_call_insn *, bool, bool, bitmap); |
6fb5fa3c | 64 | |
d4d7f1d1 RS |
65 | /* A subroutine for which BODY is part of the instruction being tested; |
66 | either the top-level pattern, or an element of a PARALLEL. The | |
67 | instruction is known not to be a bare USE or CLOBBER. */ | |
6fb5fa3c DB |
68 | |
69 | static bool | |
d4d7f1d1 | 70 | deletable_insn_p_1 (rtx body) |
6fb5fa3c | 71 | { |
6cad9859 | 72 | switch (GET_CODE (body)) |
6fb5fa3c | 73 | { |
6fb5fa3c DB |
74 | case PREFETCH: |
75 | case TRAP_IF: | |
76 | /* The UNSPEC case was added here because the ia-64 claims that | |
77 | USEs do not work after reload and generates UNSPECS rather | |
78 | than USEs. Since dce is run after reload we need to avoid | |
79 | deleting these even if they are dead. If it turns out that | |
80 | USEs really do work after reload, the ia-64 should be | |
81 | changed, and the UNSPEC case can be removed. */ | |
82 | case UNSPEC: | |
83 | return false; | |
84 | ||
d4d7f1d1 | 85 | default: |
1d65f45c | 86 | return !volatile_refs_p (body); |
d4d7f1d1 RS |
87 | } |
88 | } | |
89 | ||
234b5365 JJ |
90 | /* Don't delete calls that may throw if we cannot do so. */ |
91 | ||
92 | static bool | |
93 | can_delete_call (rtx_insn *insn) | |
94 | { | |
95 | if (cfun->can_delete_dead_exceptions && can_alter_cfg) | |
96 | return true; | |
97 | if (!insn_nothrow_p (insn)) | |
98 | return false; | |
99 | if (can_alter_cfg) | |
100 | return true; | |
101 | /* If we can't alter cfg, even when the call can't throw exceptions, it | |
102 | might have EDGE_ABNORMAL_CALL edges and so we shouldn't delete such | |
103 | calls. */ | |
104 | gcc_assert (CALL_P (insn)); | |
105 | if (BLOCK_FOR_INSN (insn) && BB_END (BLOCK_FOR_INSN (insn)) == insn) | |
106 | { | |
107 | edge e; | |
108 | edge_iterator ei; | |
109 | ||
110 | FOR_EACH_EDGE (e, ei, BLOCK_FOR_INSN (insn)->succs) | |
111 | if ((e->flags & EDGE_ABNORMAL_CALL) != 0) | |
112 | return false; | |
113 | } | |
114 | return true; | |
115 | } | |
2e6be65e | 116 | |
d4d7f1d1 RS |
117 | /* Return true if INSN is a normal instruction that can be deleted by |
118 | the DCE pass. */ | |
119 | ||
120 | static bool | |
0ece9321 | 121 | deletable_insn_p (rtx_insn *insn, bool fast, bitmap arg_stores) |
d4d7f1d1 RS |
122 | { |
123 | rtx body, x; | |
124 | int i; | |
bfac633a | 125 | df_ref def; |
d4d7f1d1 | 126 | |
5ba5ab9b KZ |
127 | if (CALL_P (insn) |
128 | /* We cannot delete calls inside of the recursive dce because | |
129 | this may cause basic blocks to be deleted and this messes up | |
130 | the rest of the stack of optimization passes. */ | |
131 | && (!df_in_progress) | |
132 | /* We cannot delete pure or const sibling calls because it is | |
133 | hard to see the result. */ | |
becfd6e5 | 134 | && (!SIBLING_CALL_P (insn)) |
5ba5ab9b KZ |
135 | /* We can delete dead const or pure calls as long as they do not |
136 | infinite loop. */ | |
becfd6e5 | 137 | && (RTL_CONST_OR_PURE_CALL_P (insn) |
9556b012 JJ |
138 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)) |
139 | /* Don't delete calls that may throw if we cannot do so. */ | |
234b5365 | 140 | && can_delete_call (insn)) |
0ece9321 DM |
141 | return find_call_stack_args (as_a <rtx_call_insn *> (insn), false, |
142 | fast, arg_stores); | |
becfd6e5 | 143 | |
642d55de EB |
144 | /* Don't delete jumps, notes and the like. */ |
145 | if (!NONJUMP_INSN_P (insn)) | |
146 | return false; | |
147 | ||
2da02156 EB |
148 | /* Don't delete insns that may throw if we cannot do so. */ |
149 | if (!(cfun->can_delete_dead_exceptions && can_alter_cfg) | |
150 | && !insn_nothrow_p (insn)) | |
642d55de EB |
151 | return false; |
152 | ||
211d71a7 | 153 | /* If INSN sets a global_reg, leave it untouched. */ |
bfac633a RS |
154 | FOR_EACH_INSN_DEF (def, insn) |
155 | if (HARD_REGISTER_NUM_P (DF_REF_REGNO (def)) | |
156 | && global_regs[DF_REF_REGNO (def)]) | |
211d71a7 | 157 | return false; |
56873e13 ES |
158 | /* Initialization of pseudo PIC register should never be removed. */ |
159 | else if (DF_REF_REG (def) == pic_offset_table_rtx | |
160 | && REGNO (pic_offset_table_rtx) >= FIRST_PSEUDO_REGISTER) | |
161 | return false; | |
211d71a7 | 162 | |
45399fdc JJ |
163 | /* Callee-save restores are needed. */ |
164 | if (RTX_FRAME_RELATED_P (insn) | |
165 | && crtl->shrink_wrapped_separate | |
166 | && find_reg_note (insn, REG_CFA_RESTORE, NULL)) | |
167 | return false; | |
168 | ||
d4d7f1d1 RS |
169 | body = PATTERN (insn); |
170 | switch (GET_CODE (body)) | |
171 | { | |
172 | case USE: | |
b5b8b0ac | 173 | case VAR_LOCATION: |
d4d7f1d1 RS |
174 | return false; |
175 | ||
6fb5fa3c DB |
176 | case CLOBBER: |
177 | if (fast) | |
178 | { | |
179 | /* A CLOBBER of a dead pseudo register serves no purpose. | |
180 | That is not necessarily true for hard registers until | |
181 | after reload. */ | |
6cad9859 | 182 | x = XEXP (body, 0); |
6fb5fa3c DB |
183 | return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed); |
184 | } | |
d4d7f1d1 | 185 | else |
6fb5fa3c DB |
186 | /* Because of the way that use-def chains are built, it is not |
187 | possible to tell if the clobber is dead because it can | |
188 | never be the target of a use-def chain. */ | |
189 | return false; | |
190 | ||
6cad9859 | 191 | case PARALLEL: |
d4d7f1d1 RS |
192 | for (i = XVECLEN (body, 0) - 1; i >= 0; i--) |
193 | if (!deletable_insn_p_1 (XVECEXP (body, 0, i))) | |
194 | return false; | |
195 | return true; | |
6cad9859 | 196 | |
6fb5fa3c | 197 | default: |
d4d7f1d1 | 198 | return deletable_insn_p_1 (body); |
6fb5fa3c DB |
199 | } |
200 | } | |
201 | ||
202 | ||
2e6be65e | 203 | /* Return true if INSN has been marked as needed. */ |
6fb5fa3c DB |
204 | |
205 | static inline int | |
0ece9321 | 206 | marked_insn_p (rtx_insn *insn) |
6fb5fa3c | 207 | { |
50e94c7e SB |
208 | /* Artificial defs are always needed and they do not have an insn. |
209 | We should never see them here. */ | |
210 | gcc_assert (insn); | |
d7c028c0 | 211 | return bitmap_bit_p (marked, INSN_UID (insn)); |
6fb5fa3c DB |
212 | } |
213 | ||
214 | ||
215 | /* If INSN has not yet been marked as needed, mark it now, and add it to | |
216 | the worklist. */ | |
217 | ||
218 | static void | |
0ece9321 | 219 | mark_insn (rtx_insn *insn, bool fast) |
6fb5fa3c DB |
220 | { |
221 | if (!marked_insn_p (insn)) | |
222 | { | |
223 | if (!fast) | |
9771b263 | 224 | worklist.safe_push (insn); |
d7c028c0 | 225 | bitmap_set_bit (marked, INSN_UID (insn)); |
6fb5fa3c DB |
226 | if (dump_file) |
227 | fprintf (dump_file, " Adding insn %d to worklist\n", INSN_UID (insn)); | |
0196c95e JJ |
228 | if (CALL_P (insn) |
229 | && !df_in_progress | |
230 | && !SIBLING_CALL_P (insn) | |
231 | && (RTL_CONST_OR_PURE_CALL_P (insn) | |
9556b012 | 232 | && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)) |
234b5365 | 233 | && can_delete_call (insn)) |
0ece9321 | 234 | find_call_stack_args (as_a <rtx_call_insn *> (insn), true, fast, NULL); |
6fb5fa3c DB |
235 | } |
236 | } | |
237 | ||
238 | ||
239 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
240 | instruction containing DEST. */ | |
241 | ||
242 | static void | |
7bc980e1 | 243 | mark_nonreg_stores_1 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
244 | { |
245 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
17d184e5 | 246 | mark_insn ((rtx_insn *) data, true); |
6fb5fa3c DB |
247 | } |
248 | ||
249 | ||
250 | /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
251 | instruction containing DEST. */ | |
252 | ||
253 | static void | |
7bc980e1 | 254 | mark_nonreg_stores_2 (rtx dest, const_rtx pattern, void *data) |
6fb5fa3c DB |
255 | { |
256 | if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
17d184e5 | 257 | mark_insn ((rtx_insn *) data, false); |
6fb5fa3c DB |
258 | } |
259 | ||
260 | ||
e8448ba5 | 261 | /* Mark INSN if it stores to a non-register destination. */ |
6fb5fa3c DB |
262 | |
263 | static void | |
e8448ba5 | 264 | mark_nonreg_stores (rtx_insn *insn, bool fast) |
6fb5fa3c DB |
265 | { |
266 | if (fast) | |
e8448ba5 | 267 | note_stores (insn, mark_nonreg_stores_1, insn); |
6fb5fa3c | 268 | else |
e8448ba5 | 269 | note_stores (insn, mark_nonreg_stores_2, insn); |
6fb5fa3c DB |
270 | } |
271 | ||
272 | ||
7eb87420 | 273 | /* Return true if a store to SIZE bytes, starting OFF bytes from stack pointer, |
2e0642cd JJ |
274 | is a call argument store, and clear corresponding bits from SP_BYTES |
275 | bitmap if it is. */ | |
276 | ||
277 | static bool | |
7eb87420 RS |
278 | check_argument_store (HOST_WIDE_INT size, HOST_WIDE_INT off, |
279 | HOST_WIDE_INT min_sp_off, HOST_WIDE_INT max_sp_off, | |
280 | bitmap sp_bytes) | |
2e0642cd JJ |
281 | { |
282 | HOST_WIDE_INT byte; | |
7eb87420 | 283 | for (byte = off; byte < off + size; byte++) |
2e0642cd JJ |
284 | { |
285 | if (byte < min_sp_off | |
286 | || byte >= max_sp_off | |
287 | || !bitmap_clear_bit (sp_bytes, byte - min_sp_off)) | |
288 | return false; | |
289 | } | |
290 | return true; | |
291 | } | |
292 | ||
1b4d15e8 JJ |
293 | /* If MEM has sp address, return 0, if it has sp + const address, |
294 | return that const, if it has reg address where reg is set to sp + const | |
295 | and FAST is false, return const, otherwise return | |
296 | INTTYPE_MINUMUM (HOST_WIDE_INT). */ | |
297 | ||
298 | static HOST_WIDE_INT | |
299 | sp_based_mem_offset (rtx_call_insn *call_insn, const_rtx mem, bool fast) | |
300 | { | |
301 | HOST_WIDE_INT off = 0; | |
302 | rtx addr = XEXP (mem, 0); | |
303 | if (GET_CODE (addr) == PLUS | |
304 | && REG_P (XEXP (addr, 0)) | |
305 | && CONST_INT_P (XEXP (addr, 1))) | |
306 | { | |
307 | off = INTVAL (XEXP (addr, 1)); | |
308 | addr = XEXP (addr, 0); | |
309 | } | |
310 | if (addr == stack_pointer_rtx) | |
311 | return off; | |
312 | ||
313 | if (!REG_P (addr) || fast) | |
314 | return INTTYPE_MINIMUM (HOST_WIDE_INT); | |
315 | ||
316 | /* If not fast, use chains to see if addr wasn't set to sp + offset. */ | |
317 | df_ref use; | |
318 | FOR_EACH_INSN_USE (use, call_insn) | |
319 | if (rtx_equal_p (addr, DF_REF_REG (use))) | |
320 | break; | |
321 | ||
322 | if (use == NULL) | |
323 | return INTTYPE_MINIMUM (HOST_WIDE_INT); | |
324 | ||
325 | struct df_link *defs; | |
326 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
327 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) | |
328 | break; | |
329 | ||
330 | if (defs == NULL) | |
331 | return INTTYPE_MINIMUM (HOST_WIDE_INT); | |
332 | ||
333 | rtx set = single_set (DF_REF_INSN (defs->ref)); | |
334 | if (!set) | |
335 | return INTTYPE_MINIMUM (HOST_WIDE_INT); | |
336 | ||
337 | if (GET_CODE (SET_SRC (set)) != PLUS | |
338 | || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
339 | || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
340 | return INTTYPE_MINIMUM (HOST_WIDE_INT); | |
341 | ||
342 | off += INTVAL (XEXP (SET_SRC (set), 1)); | |
343 | return off; | |
344 | } | |
2e0642cd | 345 | |
76416d89 JJ |
346 | /* Data for check_argument_load called via note_uses. */ |
347 | struct check_argument_load_data { | |
348 | bitmap sp_bytes; | |
349 | HOST_WIDE_INT min_sp_off, max_sp_off; | |
350 | rtx_call_insn *call_insn; | |
351 | bool fast; | |
352 | bool load_found; | |
353 | }; | |
354 | ||
355 | /* Helper function for find_call_stack_args. Check if there are | |
356 | any loads from the argument slots in between the const/pure call | |
357 | and store to the argument slot, set LOAD_FOUND if any is found. */ | |
358 | ||
359 | static void | |
360 | check_argument_load (rtx *loc, void *data) | |
361 | { | |
362 | struct check_argument_load_data *d | |
363 | = (struct check_argument_load_data *) data; | |
364 | subrtx_iterator::array_type array; | |
365 | FOR_EACH_SUBRTX (iter, array, *loc, NONCONST) | |
366 | { | |
367 | const_rtx mem = *iter; | |
368 | HOST_WIDE_INT size; | |
369 | if (MEM_P (mem) | |
370 | && MEM_SIZE_KNOWN_P (mem) | |
371 | && MEM_SIZE (mem).is_constant (&size)) | |
372 | { | |
373 | HOST_WIDE_INT off = sp_based_mem_offset (d->call_insn, mem, d->fast); | |
374 | if (off != INTTYPE_MINIMUM (HOST_WIDE_INT) | |
375 | && off < d->max_sp_off | |
376 | && off + size > d->min_sp_off) | |
377 | for (HOST_WIDE_INT byte = MAX (off, d->min_sp_off); | |
378 | byte < MIN (off + size, d->max_sp_off); byte++) | |
379 | if (bitmap_bit_p (d->sp_bytes, byte - d->min_sp_off)) | |
380 | { | |
381 | d->load_found = true; | |
382 | return; | |
383 | } | |
384 | } | |
385 | } | |
386 | } | |
387 | ||
0196c95e JJ |
388 | /* Try to find all stack stores of CALL_INSN arguments if |
389 | ACCUMULATE_OUTGOING_ARGS. If all stack stores have been found | |
390 | and it is therefore safe to eliminate the call, return true, | |
391 | otherwise return false. This function should be first called | |
392 | with DO_MARK false, and only when the CALL_INSN is actually | |
393 | going to be marked called again with DO_MARK true. */ | |
394 | ||
395 | static bool | |
0ece9321 | 396 | find_call_stack_args (rtx_call_insn *call_insn, bool do_mark, bool fast, |
0196c95e JJ |
397 | bitmap arg_stores) |
398 | { | |
0ece9321 DM |
399 | rtx p; |
400 | rtx_insn *insn, *prev_insn; | |
0196c95e JJ |
401 | bool ret; |
402 | HOST_WIDE_INT min_sp_off, max_sp_off; | |
403 | bitmap sp_bytes; | |
404 | ||
405 | gcc_assert (CALL_P (call_insn)); | |
406 | if (!ACCUMULATE_OUTGOING_ARGS) | |
407 | return true; | |
408 | ||
409 | if (!do_mark) | |
410 | { | |
411 | gcc_assert (arg_stores); | |
412 | bitmap_clear (arg_stores); | |
413 | } | |
414 | ||
415 | min_sp_off = INTTYPE_MAXIMUM (HOST_WIDE_INT); | |
416 | max_sp_off = 0; | |
417 | ||
418 | /* First determine the minimum and maximum offset from sp for | |
419 | stored arguments. */ | |
420 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
421 | if (GET_CODE (XEXP (p, 0)) == USE | |
422 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
423 | { | |
1b4d15e8 JJ |
424 | rtx mem = XEXP (XEXP (p, 0), 0); |
425 | HOST_WIDE_INT size; | |
d05d7551 | 426 | if (!MEM_SIZE_KNOWN_P (mem) || !MEM_SIZE (mem).is_constant (&size)) |
0196c95e | 427 | return false; |
1b4d15e8 JJ |
428 | HOST_WIDE_INT off = sp_based_mem_offset (call_insn, mem, fast); |
429 | if (off == INTTYPE_MINIMUM (HOST_WIDE_INT)) | |
430 | return false; | |
0196c95e | 431 | min_sp_off = MIN (min_sp_off, off); |
f5541398 | 432 | max_sp_off = MAX (max_sp_off, off + size); |
0196c95e JJ |
433 | } |
434 | ||
435 | if (min_sp_off >= max_sp_off) | |
436 | return true; | |
437 | sp_bytes = BITMAP_ALLOC (NULL); | |
438 | ||
439 | /* Set bits in SP_BYTES bitmap for bytes relative to sp + min_sp_off | |
440 | which contain arguments. Checking has been done in the previous | |
441 | loop. */ | |
442 | for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
443 | if (GET_CODE (XEXP (p, 0)) == USE | |
444 | && MEM_P (XEXP (XEXP (p, 0), 0))) | |
445 | { | |
1b4d15e8 | 446 | rtx mem = XEXP (XEXP (p, 0), 0); |
d05d7551 | 447 | /* Checked in the previous iteration. */ |
1b4d15e8 JJ |
448 | HOST_WIDE_INT size = MEM_SIZE (mem).to_constant (); |
449 | HOST_WIDE_INT off = sp_based_mem_offset (call_insn, mem, fast); | |
450 | gcc_checking_assert (off != INTTYPE_MINIMUM (HOST_WIDE_INT)); | |
451 | for (HOST_WIDE_INT byte = off; byte < off + size; byte++) | |
452 | if (!bitmap_set_bit (sp_bytes, byte - min_sp_off)) | |
453 | gcc_unreachable (); | |
0196c95e JJ |
454 | } |
455 | ||
456 | /* Walk backwards, looking for argument stores. The search stops | |
76416d89 JJ |
457 | when seeing another call, sp adjustment, memory store other than |
458 | argument store or a read from an argument stack slot. */ | |
459 | struct check_argument_load_data data | |
460 | = { sp_bytes, min_sp_off, max_sp_off, call_insn, fast, false }; | |
0196c95e JJ |
461 | ret = false; |
462 | for (insn = PREV_INSN (call_insn); insn; insn = prev_insn) | |
463 | { | |
0196c95e | 464 | if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn))) |
0ece9321 | 465 | prev_insn = NULL; |
0196c95e JJ |
466 | else |
467 | prev_insn = PREV_INSN (insn); | |
468 | ||
469 | if (CALL_P (insn)) | |
470 | break; | |
471 | ||
2e0642cd | 472 | if (!NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
473 | continue; |
474 | ||
1b4d15e8 | 475 | rtx set = single_set (insn); |
0196c95e JJ |
476 | if (!set || SET_DEST (set) == stack_pointer_rtx) |
477 | break; | |
478 | ||
76416d89 JJ |
479 | note_uses (&PATTERN (insn), check_argument_load, &data); |
480 | if (data.load_found) | |
481 | break; | |
482 | ||
0196c95e JJ |
483 | if (!MEM_P (SET_DEST (set))) |
484 | continue; | |
485 | ||
1b4d15e8 JJ |
486 | rtx mem = SET_DEST (set); |
487 | HOST_WIDE_INT off = sp_based_mem_offset (call_insn, mem, fast); | |
488 | if (off == INTTYPE_MINIMUM (HOST_WIDE_INT)) | |
489 | break; | |
0196c95e | 490 | |
d05d7551 | 491 | HOST_WIDE_INT size; |
7eb87420 | 492 | if (!MEM_SIZE_KNOWN_P (mem) |
d05d7551 RS |
493 | || !MEM_SIZE (mem).is_constant (&size) |
494 | || !check_argument_store (size, off, min_sp_off, | |
2e0642cd | 495 | max_sp_off, sp_bytes)) |
0196c95e JJ |
496 | break; |
497 | ||
0196c95e JJ |
498 | if (!deletable_insn_p (insn, fast, NULL)) |
499 | break; | |
500 | ||
501 | if (do_mark) | |
502 | mark_insn (insn, fast); | |
503 | else | |
504 | bitmap_set_bit (arg_stores, INSN_UID (insn)); | |
505 | ||
506 | if (bitmap_empty_p (sp_bytes)) | |
507 | { | |
508 | ret = true; | |
509 | break; | |
510 | } | |
511 | } | |
512 | ||
513 | BITMAP_FREE (sp_bytes); | |
514 | if (!ret && arg_stores) | |
515 | bitmap_clear (arg_stores); | |
516 | ||
517 | return ret; | |
518 | } | |
519 | ||
520 | ||
885c9b5d EB |
521 | /* Remove all REG_EQUAL and REG_EQUIV notes referring to the registers INSN |
522 | writes to. */ | |
6fb5fa3c DB |
523 | |
524 | static void | |
0ece9321 | 525 | remove_reg_equal_equiv_notes_for_defs (rtx_insn *insn) |
6fb5fa3c | 526 | { |
bfac633a | 527 | df_ref def; |
885c9b5d | 528 | |
bfac633a RS |
529 | FOR_EACH_INSN_DEF (def, insn) |
530 | remove_reg_equal_equiv_notes_for_regno (DF_REF_REGNO (def)); | |
6fb5fa3c DB |
531 | } |
532 | ||
a7a110bb AO |
533 | /* Scan all BBs for debug insns and reset those that reference values |
534 | defined in unmarked insns. */ | |
535 | ||
536 | static void | |
537 | reset_unmarked_insns_debug_uses (void) | |
538 | { | |
539 | basic_block bb; | |
0ece9321 | 540 | rtx_insn *insn, *next; |
a7a110bb | 541 | |
4f42035e | 542 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
a7a110bb AO |
543 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
544 | if (DEBUG_INSN_P (insn)) | |
545 | { | |
bfac633a | 546 | df_ref use; |
a7a110bb | 547 | |
bfac633a | 548 | FOR_EACH_INSN_USE (use, insn) |
a7a110bb | 549 | { |
a7a110bb AO |
550 | struct df_link *defs; |
551 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
552 | { | |
0ece9321 | 553 | rtx_insn *ref_insn; |
a7a110bb AO |
554 | if (DF_REF_IS_ARTIFICIAL (defs->ref)) |
555 | continue; | |
8ced31fe JJ |
556 | ref_insn = DF_REF_INSN (defs->ref); |
557 | if (!marked_insn_p (ref_insn)) | |
a7a110bb AO |
558 | break; |
559 | } | |
560 | if (!defs) | |
561 | continue; | |
562 | /* ??? FIXME could we propagate the values assigned to | |
563 | each of the DEFs? */ | |
564 | INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC (); | |
565 | df_insn_rescan_debug_internal (insn); | |
8ced31fe | 566 | break; |
a7a110bb AO |
567 | } |
568 | } | |
569 | } | |
6fb5fa3c | 570 | |
9ed7b221 | 571 | /* Delete every instruction that hasn't been marked. */ |
6fb5fa3c DB |
572 | |
573 | static void | |
574 | delete_unmarked_insns (void) | |
575 | { | |
576 | basic_block bb; | |
0ece9321 | 577 | rtx_insn *insn, *next; |
5ba5ab9b | 578 | bool must_clean = false; |
6fb5fa3c | 579 | |
4f42035e | 580 | FOR_EACH_BB_REVERSE_FN (bb, cfun) |
cd3f1729 | 581 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
a7a110bb | 582 | if (NONDEBUG_INSN_P (insn)) |
6fb5fa3c | 583 | { |
6f21dc3c JJ |
584 | rtx turn_into_use = NULL_RTX; |
585 | ||
9ed7b221 | 586 | /* Always delete no-op moves. */ |
c6477561 JJ |
587 | if (noop_move_p (insn) |
588 | /* Unless the no-op move can throw and we are not allowed | |
589 | to alter cfg. */ | |
590 | && (!cfun->can_throw_non_call_exceptions | |
591 | || (cfun->can_delete_dead_exceptions && can_alter_cfg) | |
592 | || insn_nothrow_p (insn))) | |
6f21dc3c JJ |
593 | { |
594 | if (RTX_FRAME_RELATED_P (insn)) | |
595 | turn_into_use | |
596 | = find_reg_note (insn, REG_CFA_RESTORE, NULL); | |
597 | if (turn_into_use && REG_P (XEXP (turn_into_use, 0))) | |
598 | turn_into_use = XEXP (turn_into_use, 0); | |
599 | else | |
600 | turn_into_use = NULL_RTX; | |
601 | } | |
9ed7b221 | 602 | |
9ed7b221 | 603 | /* Otherwise rely only on the DCE algorithm. */ |
6fb5fa3c DB |
604 | else if (marked_insn_p (insn)) |
605 | continue; | |
606 | ||
cd3f1729 KZ |
607 | /* Beware that reaching a dbg counter limit here can result |
608 | in miscompiled file. This occurs when a group of insns | |
609 | must be deleted together, typically because the kept insn | |
610 | depends on the output from the deleted insn. Deleting | |
611 | this insns in reverse order (both at the bb level and | |
612 | when looking at the blocks) minimizes this, but does not | |
613 | eliminate it, since it is possible for the using insn to | |
614 | be top of a block and the producer to be at the bottom of | |
615 | the block. However, in most cases this will only result | |
616 | in an uninitialized use of an insn that is dead anyway. | |
617 | ||
618 | However, there is one rare case that will cause a | |
619 | miscompile: deletion of non-looping pure and constant | |
620 | calls on a machine where ACCUMULATE_OUTGOING_ARGS is true. | |
621 | In this case it is possible to remove the call, but leave | |
622 | the argument pushes to the stack. Because of the changes | |
623 | to the stack pointer, this will almost always lead to a | |
624 | miscompile. */ | |
6fb5fa3c DB |
625 | if (!dbg_cnt (dce)) |
626 | continue; | |
627 | ||
628 | if (dump_file) | |
629 | fprintf (dump_file, "DCE: Deleting insn %d\n", INSN_UID (insn)); | |
630 | ||
885c9b5d | 631 | /* Before we delete the insn we have to remove the REG_EQUAL notes |
9ed7b221 | 632 | for the destination regs in order to avoid dangling notes. */ |
885c9b5d | 633 | remove_reg_equal_equiv_notes_for_defs (insn); |
6fb5fa3c | 634 | |
6f21dc3c JJ |
635 | if (turn_into_use) |
636 | { | |
637 | /* Don't remove frame related noop moves if they cary | |
638 | REG_CFA_RESTORE note, while we don't need to emit any code, | |
639 | we need it to emit the CFI restore note. */ | |
640 | PATTERN (insn) | |
641 | = gen_rtx_USE (GET_MODE (turn_into_use), turn_into_use); | |
642 | INSN_CODE (insn) = -1; | |
643 | df_insn_rescan (insn); | |
644 | } | |
645 | else | |
646 | /* Now delete the insn. */ | |
c6477561 | 647 | must_clean |= delete_insn_and_edges (insn); |
6fb5fa3c | 648 | } |
5ba5ab9b KZ |
649 | |
650 | /* Deleted a pure or const call. */ | |
651 | if (must_clean) | |
c6477561 JJ |
652 | { |
653 | gcc_assert (can_alter_cfg); | |
654 | delete_unreachable_blocks (); | |
696c5b27 | 655 | free_dominance_info (CDI_DOMINATORS); |
c6477561 | 656 | } |
6fb5fa3c DB |
657 | } |
658 | ||
659 | ||
6fb5fa3c DB |
660 | /* Go through the instructions and mark those whose necessity is not |
661 | dependent on inter-instruction information. Make sure all other | |
662 | instructions are not marked. */ | |
663 | ||
664 | static void | |
665 | prescan_insns_for_dce (bool fast) | |
666 | { | |
667 | basic_block bb; | |
0ece9321 | 668 | rtx_insn *insn, *prev; |
0196c95e JJ |
669 | bitmap arg_stores = NULL; |
670 | ||
6fb5fa3c DB |
671 | if (dump_file) |
672 | fprintf (dump_file, "Finding needed instructions:\n"); | |
0196c95e JJ |
673 | |
674 | if (!df_in_progress && ACCUMULATE_OUTGOING_ARGS) | |
675 | arg_stores = BITMAP_ALLOC (NULL); | |
676 | ||
11cd3bed | 677 | FOR_EACH_BB_FN (bb, cfun) |
0196c95e JJ |
678 | { |
679 | FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev) | |
a7a110bb | 680 | if (NONDEBUG_INSN_P (insn)) |
0196c95e JJ |
681 | { |
682 | /* Don't mark argument stores now. They will be marked | |
683 | if needed when the associated CALL is marked. */ | |
684 | if (arg_stores && bitmap_bit_p (arg_stores, INSN_UID (insn))) | |
685 | continue; | |
686 | if (deletable_insn_p (insn, fast, arg_stores)) | |
e8448ba5 | 687 | mark_nonreg_stores (insn, fast); |
0196c95e JJ |
688 | else |
689 | mark_insn (insn, fast); | |
690 | } | |
691 | /* find_call_stack_args only looks at argument stores in the | |
692 | same bb. */ | |
693 | if (arg_stores) | |
694 | bitmap_clear (arg_stores); | |
695 | } | |
696 | ||
697 | if (arg_stores) | |
698 | BITMAP_FREE (arg_stores); | |
6fb5fa3c DB |
699 | |
700 | if (dump_file) | |
701 | fprintf (dump_file, "Finished finding needed instructions:\n"); | |
702 | } | |
703 | ||
704 | ||
705 | /* UD-based DSE routines. */ | |
706 | ||
6ed3da00 | 707 | /* Mark instructions that define artificially-used registers, such as |
6fb5fa3c DB |
708 | the frame pointer and the stack pointer. */ |
709 | ||
710 | static void | |
711 | mark_artificial_uses (void) | |
712 | { | |
713 | basic_block bb; | |
714 | struct df_link *defs; | |
292321a5 | 715 | df_ref use; |
6fb5fa3c | 716 | |
04a90bec | 717 | FOR_ALL_BB_FN (bb, cfun) |
292321a5 RS |
718 | FOR_EACH_ARTIFICIAL_USE (use, bb->index) |
719 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
720 | if (!DF_REF_IS_ARTIFICIAL (defs->ref)) | |
721 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
722 | } |
723 | ||
2e6be65e | 724 | |
6fb5fa3c DB |
725 | /* Mark every instruction that defines a register value that INSN uses. */ |
726 | ||
727 | static void | |
0ece9321 | 728 | mark_reg_dependencies (rtx_insn *insn) |
6fb5fa3c DB |
729 | { |
730 | struct df_link *defs; | |
bfac633a | 731 | df_ref use; |
6fb5fa3c | 732 | |
b5b8b0ac AO |
733 | if (DEBUG_INSN_P (insn)) |
734 | return; | |
735 | ||
bfac633a | 736 | FOR_EACH_INSN_USE (use, insn) |
6fb5fa3c | 737 | { |
6fb5fa3c DB |
738 | if (dump_file) |
739 | { | |
740 | fprintf (dump_file, "Processing use of "); | |
741 | print_simple_rtl (dump_file, DF_REF_REG (use)); | |
742 | fprintf (dump_file, " in insn %d:\n", INSN_UID (insn)); | |
743 | } | |
744 | for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
50e94c7e SB |
745 | if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
746 | mark_insn (DF_REF_INSN (defs->ref), false); | |
6fb5fa3c DB |
747 | } |
748 | } | |
749 | ||
750 | ||
2e6be65e EB |
751 | /* Initialize global variables for a new DCE pass. */ |
752 | ||
6fb5fa3c | 753 | static void |
2e6be65e EB |
754 | init_dce (bool fast) |
755 | { | |
756 | if (!df_in_progress) | |
757 | { | |
758 | if (!fast) | |
7b19209f SB |
759 | { |
760 | df_set_flags (DF_RD_PRUNE_DEAD_DEFS); | |
761 | df_chain_add_problem (DF_UD_CHAIN); | |
762 | } | |
2e6be65e EB |
763 | df_analyze (); |
764 | } | |
765 | ||
766 | if (dump_file) | |
767 | df_dump (dump_file); | |
768 | ||
769 | if (fast) | |
770 | { | |
771 | bitmap_obstack_initialize (&dce_blocks_bitmap_obstack); | |
772 | bitmap_obstack_initialize (&dce_tmp_bitmap_obstack); | |
2da02156 | 773 | can_alter_cfg = false; |
2e6be65e | 774 | } |
2da02156 EB |
775 | else |
776 | can_alter_cfg = true; | |
2e6be65e EB |
777 | |
778 | marked = sbitmap_alloc (get_max_uid () + 1); | |
f61e445a | 779 | bitmap_clear (marked); |
2e6be65e EB |
780 | } |
781 | ||
782 | ||
783 | /* Free the data allocated by init_dce. */ | |
784 | ||
785 | static void | |
786 | fini_dce (bool fast) | |
6fb5fa3c DB |
787 | { |
788 | sbitmap_free (marked); | |
2e6be65e EB |
789 | |
790 | if (fast) | |
791 | { | |
792 | bitmap_obstack_release (&dce_blocks_bitmap_obstack); | |
793 | bitmap_obstack_release (&dce_tmp_bitmap_obstack); | |
794 | } | |
6fb5fa3c DB |
795 | } |
796 | ||
797 | ||
798 | /* UD-chain based DCE. */ | |
799 | ||
800 | static unsigned int | |
801 | rest_of_handle_ud_dce (void) | |
802 | { | |
0ece9321 | 803 | rtx_insn *insn; |
6fb5fa3c | 804 | |
6fb5fa3c DB |
805 | init_dce (false); |
806 | ||
807 | prescan_insns_for_dce (false); | |
808 | mark_artificial_uses (); | |
9771b263 | 809 | while (worklist.length () > 0) |
6fb5fa3c | 810 | { |
9771b263 | 811 | insn = worklist.pop (); |
6fb5fa3c DB |
812 | mark_reg_dependencies (insn); |
813 | } | |
9771b263 | 814 | worklist.release (); |
2e6be65e | 815 | |
36f52e8f | 816 | if (MAY_HAVE_DEBUG_BIND_INSNS) |
a7a110bb AO |
817 | reset_unmarked_insns_debug_uses (); |
818 | ||
6fb5fa3c DB |
819 | /* Before any insns are deleted, we must remove the chains since |
820 | they are not bidirectional. */ | |
821 | df_remove_problem (df_chain); | |
822 | delete_unmarked_insns (); | |
823 | ||
2e6be65e | 824 | fini_dce (false); |
6fb5fa3c DB |
825 | return 0; |
826 | } | |
827 | ||
828 | ||
17795822 TS |
829 | namespace { |
830 | ||
831 | const pass_data pass_data_ud_rtl_dce = | |
6fb5fa3c | 832 | { |
27a4cd48 DM |
833 | RTL_PASS, /* type */ |
834 | "ud_dce", /* name */ | |
835 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
836 | TV_DCE, /* tv_id */ |
837 | 0, /* properties_required */ | |
838 | 0, /* properties_provided */ | |
839 | 0, /* properties_destroyed */ | |
840 | 0, /* todo_flags_start */ | |
3bea341f | 841 | TODO_df_finish, /* todo_flags_finish */ |
6fb5fa3c DB |
842 | }; |
843 | ||
17795822 | 844 | class pass_ud_rtl_dce : public rtl_opt_pass |
27a4cd48 DM |
845 | { |
846 | public: | |
c3284718 RS |
847 | pass_ud_rtl_dce (gcc::context *ctxt) |
848 | : rtl_opt_pass (pass_data_ud_rtl_dce, ctxt) | |
27a4cd48 DM |
849 | {} |
850 | ||
851 | /* opt_pass methods: */ | |
1a3d085c TS |
852 | virtual bool gate (function *) |
853 | { | |
854 | return optimize > 1 && flag_dce && dbg_cnt (dce_ud); | |
855 | } | |
856 | ||
be55bfe6 TS |
857 | virtual unsigned int execute (function *) |
858 | { | |
859 | return rest_of_handle_ud_dce (); | |
860 | } | |
27a4cd48 DM |
861 | |
862 | }; // class pass_ud_rtl_dce | |
863 | ||
17795822 TS |
864 | } // anon namespace |
865 | ||
27a4cd48 DM |
866 | rtl_opt_pass * |
867 | make_pass_ud_rtl_dce (gcc::context *ctxt) | |
868 | { | |
869 | return new pass_ud_rtl_dce (ctxt); | |
870 | } | |
871 | ||
2e6be65e | 872 | |
6fb5fa3c DB |
873 | /* ------------------------------------------------------------------------- |
874 | Fast DCE functions | |
875 | ------------------------------------------------------------------------- */ | |
876 | ||
cc806ac1 RS |
877 | /* Process basic block BB. Return true if the live_in set has |
878 | changed. REDO_OUT is true if the info at the bottom of the block | |
879 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
880 | artificial uses. Track global substitution of uses of dead pseudos |
881 | in debug insns using GLOBAL_DEBUG. */ | |
6fb5fa3c DB |
882 | |
883 | static bool | |
e9f950ba AO |
884 | word_dce_process_block (basic_block bb, bool redo_out, |
885 | struct dead_debug_global *global_debug) | |
6fb5fa3c DB |
886 | { |
887 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
0ece9321 | 888 | rtx_insn *insn; |
6fb5fa3c | 889 | bool block_changed; |
e9f950ba | 890 | struct dead_debug_local debug; |
6fb5fa3c DB |
891 | |
892 | if (redo_out) | |
893 | { | |
894 | /* Need to redo the live_out set of this block if when one of | |
895 | the succs of this block has had a change in it live in | |
896 | set. */ | |
897 | edge e; | |
898 | edge_iterator ei; | |
8d074192 BS |
899 | df_confluence_function_n con_fun_n = df_word_lr->problem->con_fun_n; |
900 | bitmap_clear (DF_WORD_LR_OUT (bb)); | |
6fb5fa3c DB |
901 | FOR_EACH_EDGE (e, ei, bb->succs) |
902 | (*con_fun_n) (e); | |
903 | } | |
904 | ||
905 | if (dump_file) | |
906 | { | |
907 | fprintf (dump_file, "processing block %d live out = ", bb->index); | |
8d074192 | 908 | df_print_word_regset (dump_file, DF_WORD_LR_OUT (bb)); |
6fb5fa3c DB |
909 | } |
910 | ||
8d074192 | 911 | bitmap_copy (local_live, DF_WORD_LR_OUT (bb)); |
e9f950ba | 912 | dead_debug_local_init (&debug, NULL, global_debug); |
cc806ac1 RS |
913 | |
914 | FOR_BB_INSNS_REVERSE (bb, insn) | |
1adbb361 AO |
915 | if (DEBUG_INSN_P (insn)) |
916 | { | |
bfac633a RS |
917 | df_ref use; |
918 | FOR_EACH_INSN_USE (use, insn) | |
919 | if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER | |
cf098191 RS |
920 | && known_eq (GET_MODE_SIZE (GET_MODE (DF_REF_REAL_REG (use))), |
921 | 2 * UNITS_PER_WORD) | |
bfac633a RS |
922 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use)) |
923 | && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use) + 1)) | |
924 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
1adbb361 AO |
925 | } |
926 | else if (INSN_P (insn)) | |
cc806ac1 | 927 | { |
8d074192 | 928 | bool any_changed; |
1adbb361 | 929 | |
cc806ac1 RS |
930 | /* No matter if the instruction is needed or not, we remove |
931 | any regno in the defs from the live set. */ | |
8d074192 BS |
932 | any_changed = df_word_lr_simulate_defs (insn, local_live); |
933 | if (any_changed) | |
934 | mark_insn (insn, true); | |
cc806ac1 RS |
935 | |
936 | /* On the other hand, we do not allow the dead uses to set | |
937 | anything in local_live. */ | |
938 | if (marked_insn_p (insn)) | |
8d074192 | 939 | df_word_lr_simulate_uses (insn, local_live); |
6f9e260c | 940 | |
39bc0f01 | 941 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
942 | insns. We may have to emit a debug temp even if the insn |
943 | was marked, in case the debug use was after the point of | |
944 | death. */ | |
945 | if (debug.used && !bitmap_empty_p (debug.used)) | |
1adbb361 | 946 | { |
bfac633a | 947 | df_ref def; |
1adbb361 | 948 | |
bfac633a RS |
949 | FOR_EACH_INSN_DEF (def, insn) |
950 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
85d87497 JJ |
951 | marked_insn_p (insn) |
952 | && !control_flow_insn_p (insn) | |
953 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
954 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
1adbb361 AO |
955 | } |
956 | ||
cc806ac1 RS |
957 | if (dump_file) |
958 | { | |
b8698a0f | 959 | fprintf (dump_file, "finished processing insn %d live out = ", |
cc806ac1 | 960 | INSN_UID (insn)); |
8d074192 | 961 | df_print_word_regset (dump_file, local_live); |
cc806ac1 RS |
962 | } |
963 | } | |
b8698a0f | 964 | |
8d074192 | 965 | block_changed = !bitmap_equal_p (local_live, DF_WORD_LR_IN (bb)); |
cc806ac1 | 966 | if (block_changed) |
8d074192 BS |
967 | bitmap_copy (DF_WORD_LR_IN (bb), local_live); |
968 | ||
e9f950ba | 969 | dead_debug_local_finish (&debug, NULL); |
cc806ac1 RS |
970 | BITMAP_FREE (local_live); |
971 | return block_changed; | |
972 | } | |
973 | ||
974 | ||
975 | /* Process basic block BB. Return true if the live_in set has | |
976 | changed. REDO_OUT is true if the info at the bottom of the block | |
977 | needs to be recalculated before starting. AU is the proper set of | |
e9f950ba AO |
978 | artificial uses. Track global substitution of uses of dead pseudos |
979 | in debug insns using GLOBAL_DEBUG. */ | |
cc806ac1 RS |
980 | |
981 | static bool | |
e9f950ba AO |
982 | dce_process_block (basic_block bb, bool redo_out, bitmap au, |
983 | struct dead_debug_global *global_debug) | |
cc806ac1 RS |
984 | { |
985 | bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
0ece9321 | 986 | rtx_insn *insn; |
cc806ac1 | 987 | bool block_changed; |
bfac633a | 988 | df_ref def; |
e9f950ba | 989 | struct dead_debug_local debug; |
6fb5fa3c | 990 | |
cc806ac1 | 991 | if (redo_out) |
6fb5fa3c | 992 | { |
cc806ac1 RS |
993 | /* Need to redo the live_out set of this block if when one of |
994 | the succs of this block has had a change in it live in | |
995 | set. */ | |
996 | edge e; | |
997 | edge_iterator ei; | |
998 | df_confluence_function_n con_fun_n = df_lr->problem->con_fun_n; | |
999 | bitmap_clear (DF_LR_OUT (bb)); | |
1000 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1001 | (*con_fun_n) (e); | |
6fb5fa3c DB |
1002 | } |
1003 | ||
cc806ac1 | 1004 | if (dump_file) |
6fb5fa3c | 1005 | { |
fafe34f9 | 1006 | fprintf (dump_file, "processing block %d lr out = ", bb->index); |
cc806ac1 | 1007 | df_print_regset (dump_file, DF_LR_OUT (bb)); |
6fb5fa3c DB |
1008 | } |
1009 | ||
cc806ac1 RS |
1010 | bitmap_copy (local_live, DF_LR_OUT (bb)); |
1011 | ||
02b47899 | 1012 | df_simulate_initialize_backwards (bb, local_live); |
e9f950ba | 1013 | dead_debug_local_init (&debug, NULL, global_debug); |
541d3103 | 1014 | |
6fb5fa3c | 1015 | FOR_BB_INSNS_REVERSE (bb, insn) |
1adbb361 AO |
1016 | if (DEBUG_INSN_P (insn)) |
1017 | { | |
bfac633a RS |
1018 | df_ref use; |
1019 | FOR_EACH_INSN_USE (use, insn) | |
1020 | if (!bitmap_bit_p (local_live, DF_REF_REGNO (use)) | |
1021 | && !bitmap_bit_p (au, DF_REF_REGNO (use))) | |
1022 | dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
1adbb361 AO |
1023 | } |
1024 | else if (INSN_P (insn)) | |
6fb5fa3c | 1025 | { |
f251709a | 1026 | bool needed = marked_insn_p (insn); |
9ed7b221 EB |
1027 | |
1028 | /* The insn is needed if there is someone who uses the output. */ | |
f251709a | 1029 | if (!needed) |
bfac633a RS |
1030 | FOR_EACH_INSN_DEF (def, insn) |
1031 | if (bitmap_bit_p (local_live, DF_REF_REGNO (def)) | |
1032 | || bitmap_bit_p (au, DF_REF_REGNO (def))) | |
39bc0f01 AO |
1033 | { |
1034 | needed = true; | |
1035 | mark_insn (insn, true); | |
1036 | break; | |
1037 | } | |
b8698a0f | 1038 | |
6fb5fa3c DB |
1039 | /* No matter if the instruction is needed or not, we remove |
1040 | any regno in the defs from the live set. */ | |
1041 | df_simulate_defs (insn, local_live); | |
1042 | ||
1043 | /* On the other hand, we do not allow the dead uses to set | |
1044 | anything in local_live. */ | |
f251709a | 1045 | if (needed) |
6fb5fa3c | 1046 | df_simulate_uses (insn, local_live); |
6f9e260c | 1047 | |
39bc0f01 | 1048 | /* Insert debug temps for dead REGs used in subsequent debug |
6f9e260c AO |
1049 | insns. We may have to emit a debug temp even if the insn |
1050 | was marked, in case the debug use was after the point of | |
1051 | death. */ | |
1052 | if (debug.used && !bitmap_empty_p (debug.used)) | |
bfac633a RS |
1053 | FOR_EACH_INSN_DEF (def, insn) |
1054 | dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
85d87497 JJ |
1055 | needed && !control_flow_insn_p (insn) |
1056 | ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
1057 | : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
6fb5fa3c | 1058 | } |
b8698a0f | 1059 | |
e9f950ba | 1060 | dead_debug_local_finish (&debug, NULL); |
02b47899 | 1061 | df_simulate_finalize_backwards (bb, local_live); |
6fb5fa3c DB |
1062 | |
1063 | block_changed = !bitmap_equal_p (local_live, DF_LR_IN (bb)); | |
1064 | if (block_changed) | |
1065 | bitmap_copy (DF_LR_IN (bb), local_live); | |
1066 | ||
1067 | BITMAP_FREE (local_live); | |
1068 | return block_changed; | |
1069 | } | |
1070 | ||
2e6be65e | 1071 | |
8d074192 BS |
1072 | /* Perform fast DCE once initialization is done. If WORD_LEVEL is |
1073 | true, use the word level dce, otherwise do it at the pseudo | |
cc806ac1 | 1074 | level. */ |
2e6be65e | 1075 | |
6fb5fa3c | 1076 | static void |
8d074192 | 1077 | fast_dce (bool word_level) |
6fb5fa3c DB |
1078 | { |
1079 | int *postorder = df_get_postorder (DF_BACKWARD); | |
1080 | int n_blocks = df_get_n_blocks (DF_BACKWARD); | |
6fb5fa3c DB |
1081 | /* The set of blocks that have been seen on this iteration. */ |
1082 | bitmap processed = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1083 | /* The set of blocks that need to have the out vectors reset because | |
1084 | the in of one of their successors has changed. */ | |
1085 | bitmap redo_out = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1086 | bitmap all_blocks = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
1087 | bool global_changed = true; | |
cc806ac1 RS |
1088 | |
1089 | /* These regs are considered always live so if they end up dying | |
1090 | because of some def, we need to bring the back again. Calling | |
1091 | df_simulate_fixup_sets has the disadvantage of calling | |
1092 | bb_has_eh_pred once per insn, so we cache the information | |
1093 | here. */ | |
a7e3698d JH |
1094 | bitmap au = &df->regular_block_artificial_uses; |
1095 | bitmap au_eh = &df->eh_block_artificial_uses; | |
9ed7b221 | 1096 | int i; |
e9f950ba | 1097 | struct dead_debug_global global_debug; |
6fb5fa3c DB |
1098 | |
1099 | prescan_insns_for_dce (true); | |
1100 | ||
1101 | for (i = 0; i < n_blocks; i++) | |
1102 | bitmap_set_bit (all_blocks, postorder[i]); | |
1103 | ||
e9f950ba AO |
1104 | dead_debug_global_init (&global_debug, NULL); |
1105 | ||
6fb5fa3c DB |
1106 | while (global_changed) |
1107 | { | |
1108 | global_changed = false; | |
9ed7b221 | 1109 | |
6fb5fa3c DB |
1110 | for (i = 0; i < n_blocks; i++) |
1111 | { | |
1112 | int index = postorder[i]; | |
06e28de2 | 1113 | basic_block bb = BASIC_BLOCK_FOR_FN (cfun, index); |
6fb5fa3c DB |
1114 | bool local_changed; |
1115 | ||
1116 | if (index < NUM_FIXED_BLOCKS) | |
1117 | { | |
1118 | bitmap_set_bit (processed, index); | |
1119 | continue; | |
1120 | } | |
1121 | ||
8d074192 | 1122 | if (word_level) |
b8698a0f | 1123 | local_changed |
e9f950ba AO |
1124 | = word_dce_process_block (bb, bitmap_bit_p (redo_out, index), |
1125 | &global_debug); | |
cc806ac1 | 1126 | else |
b8698a0f | 1127 | local_changed |
cc806ac1 | 1128 | = dce_process_block (bb, bitmap_bit_p (redo_out, index), |
e9f950ba AO |
1129 | bb_has_eh_pred (bb) ? au_eh : au, |
1130 | &global_debug); | |
6fb5fa3c | 1131 | bitmap_set_bit (processed, index); |
b8698a0f | 1132 | |
6fb5fa3c DB |
1133 | if (local_changed) |
1134 | { | |
1135 | edge e; | |
1136 | edge_iterator ei; | |
1137 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1138 | if (bitmap_bit_p (processed, e->src->index)) | |
1139 | /* Be tricky about when we need to iterate the | |
1140 | analysis. We only have redo the analysis if the | |
1141 | bitmaps change at the top of a block that is the | |
1142 | entry to a loop. */ | |
1143 | global_changed = true; | |
1144 | else | |
1145 | bitmap_set_bit (redo_out, e->src->index); | |
1146 | } | |
1147 | } | |
b8698a0f | 1148 | |
6fb5fa3c DB |
1149 | if (global_changed) |
1150 | { | |
1151 | /* Turn off the RUN_DCE flag to prevent recursive calls to | |
1152 | dce. */ | |
1153 | int old_flag = df_clear_flags (DF_LR_RUN_DCE); | |
1154 | ||
1155 | /* So something was deleted that requires a redo. Do it on | |
1156 | the cheap. */ | |
1157 | delete_unmarked_insns (); | |
f61e445a | 1158 | bitmap_clear (marked); |
6fb5fa3c DB |
1159 | bitmap_clear (processed); |
1160 | bitmap_clear (redo_out); | |
b8698a0f | 1161 | |
6fb5fa3c DB |
1162 | /* We do not need to rescan any instructions. We only need |
1163 | to redo the dataflow equations for the blocks that had a | |
1164 | change at the top of the block. Then we need to redo the | |
b8698a0f | 1165 | iteration. */ |
8d074192 BS |
1166 | if (word_level) |
1167 | df_analyze_problem (df_word_lr, all_blocks, postorder, n_blocks); | |
cc806ac1 RS |
1168 | else |
1169 | df_analyze_problem (df_lr, all_blocks, postorder, n_blocks); | |
6fb5fa3c DB |
1170 | |
1171 | if (old_flag & DF_LR_RUN_DCE) | |
1172 | df_set_flags (DF_LR_RUN_DCE); | |
9ed7b221 | 1173 | |
6fb5fa3c DB |
1174 | prescan_insns_for_dce (true); |
1175 | } | |
6fb5fa3c DB |
1176 | } |
1177 | ||
e9f950ba AO |
1178 | dead_debug_global_finish (&global_debug, NULL); |
1179 | ||
6fb5fa3c DB |
1180 | delete_unmarked_insns (); |
1181 | ||
1182 | BITMAP_FREE (processed); | |
1183 | BITMAP_FREE (redo_out); | |
1184 | BITMAP_FREE (all_blocks); | |
1185 | } | |
1186 | ||
1187 | ||
cc806ac1 | 1188 | /* Fast register level DCE. */ |
6fb5fa3c DB |
1189 | |
1190 | static unsigned int | |
1191 | rest_of_handle_fast_dce (void) | |
1192 | { | |
1193 | init_dce (true); | |
cc806ac1 RS |
1194 | fast_dce (false); |
1195 | fini_dce (true); | |
1196 | return 0; | |
1197 | } | |
1198 | ||
1199 | ||
1200 | /* Fast byte level DCE. */ | |
1201 | ||
8d074192 BS |
1202 | void |
1203 | run_word_dce (void) | |
cc806ac1 | 1204 | { |
25aef556 BS |
1205 | int old_flags; |
1206 | ||
1207 | if (!flag_dce) | |
1208 | return; | |
1209 | ||
8d074192 | 1210 | timevar_push (TV_DCE); |
25aef556 | 1211 | old_flags = df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
8d074192 | 1212 | df_word_lr_add_problem (); |
cc806ac1 RS |
1213 | init_dce (true); |
1214 | fast_dce (true); | |
2e6be65e | 1215 | fini_dce (true); |
25aef556 | 1216 | df_set_flags (old_flags); |
8d074192 | 1217 | timevar_pop (TV_DCE); |
6fb5fa3c DB |
1218 | } |
1219 | ||
1220 | ||
1221 | /* This is an internal call that is used by the df live register | |
1222 | problem to run fast dce as a side effect of creating the live | |
1223 | information. The stack is organized so that the lr problem is run, | |
1224 | this pass is run, which updates the live info and the df scanning | |
1225 | info, and then returns to allow the rest of the problems to be run. | |
1226 | ||
1227 | This can be called by elsewhere but it will not update the bit | |
2e6be65e | 1228 | vectors for any other problems than LR. */ |
6fb5fa3c DB |
1229 | |
1230 | void | |
1231 | run_fast_df_dce (void) | |
1232 | { | |
1233 | if (flag_dce) | |
1234 | { | |
1235 | /* If dce is able to delete something, it has to happen | |
1236 | immediately. Otherwise there will be problems handling the | |
1237 | eq_notes. */ | |
81f40b79 ILT |
1238 | int old_flags = |
1239 | df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); | |
1240 | ||
6fb5fa3c DB |
1241 | df_in_progress = true; |
1242 | rest_of_handle_fast_dce (); | |
2e6be65e EB |
1243 | df_in_progress = false; |
1244 | ||
6fb5fa3c DB |
1245 | df_set_flags (old_flags); |
1246 | } | |
1247 | } | |
1248 | ||
2e6be65e | 1249 | |
9ed7b221 EB |
1250 | /* Run a fast DCE pass. */ |
1251 | ||
1252 | void | |
1253 | run_fast_dce (void) | |
6fb5fa3c | 1254 | { |
9ed7b221 EB |
1255 | if (flag_dce) |
1256 | rest_of_handle_fast_dce (); | |
6fb5fa3c DB |
1257 | } |
1258 | ||
1259 | ||
17795822 TS |
1260 | namespace { |
1261 | ||
1262 | const pass_data pass_data_fast_rtl_dce = | |
6fb5fa3c | 1263 | { |
27a4cd48 DM |
1264 | RTL_PASS, /* type */ |
1265 | "rtl_dce", /* name */ | |
1266 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
1267 | TV_DCE, /* tv_id */ |
1268 | 0, /* properties_required */ | |
1269 | 0, /* properties_provided */ | |
1270 | 0, /* properties_destroyed */ | |
1271 | 0, /* todo_flags_start */ | |
3bea341f | 1272 | TODO_df_finish, /* todo_flags_finish */ |
6fb5fa3c | 1273 | }; |
27a4cd48 | 1274 | |
17795822 | 1275 | class pass_fast_rtl_dce : public rtl_opt_pass |
27a4cd48 DM |
1276 | { |
1277 | public: | |
c3284718 RS |
1278 | pass_fast_rtl_dce (gcc::context *ctxt) |
1279 | : rtl_opt_pass (pass_data_fast_rtl_dce, ctxt) | |
27a4cd48 DM |
1280 | {} |
1281 | ||
1282 | /* opt_pass methods: */ | |
1a3d085c TS |
1283 | virtual bool gate (function *) |
1284 | { | |
1285 | return optimize > 0 && flag_dce && dbg_cnt (dce_fast); | |
1286 | } | |
1287 | ||
be55bfe6 TS |
1288 | virtual unsigned int execute (function *) |
1289 | { | |
1290 | return rest_of_handle_fast_dce (); | |
1291 | } | |
27a4cd48 DM |
1292 | |
1293 | }; // class pass_fast_rtl_dce | |
1294 | ||
17795822 TS |
1295 | } // anon namespace |
1296 | ||
27a4cd48 DM |
1297 | rtl_opt_pass * |
1298 | make_pass_fast_rtl_dce (gcc::context *ctxt) | |
1299 | { | |
1300 | return new pass_fast_rtl_dce (ctxt); | |
1301 | } |