Mercurial > hg > CbC > CbC_gcc
annotate gcc/dce.c @ 158:494b0b89df80 default tip
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| author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Mon, 25 May 2020 18:13:55 +0900 |
| parents | 1830386684a0 |
| children |
| rev | line source |
|---|---|
| 0 | 1 /* RTL dead code elimination. |
| 145 | 2 Copyright (C) 2005-2020 Free Software Foundation, Inc. |
| 0 | 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 | |
| 8 Software Foundation; either version 3, or (at your option) any later | |
| 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 | |
| 17 along with GCC; see the file COPYING3. If not see | |
| 18 <http://www.gnu.org/licenses/>. */ | |
| 19 | |
| 20 #include "config.h" | |
| 21 #include "system.h" | |
| 22 #include "coretypes.h" | |
| 111 | 23 #include "backend.h" |
| 0 | 24 #include "rtl.h" |
| 25 #include "tree.h" | |
| 111 | 26 #include "predict.h" |
| 0 | 27 #include "df.h" |
| 111 | 28 #include "memmodel.h" |
| 29 #include "tm_p.h" | |
| 30 #include "emit-rtl.h" /* FIXME: Can go away once crtl is moved to rtl.h. */ | |
| 31 #include "cfgrtl.h" | |
| 32 #include "cfgbuild.h" | |
| 33 #include "cfgcleanup.h" | |
| 0 | 34 #include "dce.h" |
| 111 | 35 #include "valtrack.h" |
| 0 | 36 #include "tree-pass.h" |
| 37 #include "dbgcnt.h" | |
| 145 | 38 #include "rtl-iter.h" |
| 0 | 39 |
| 40 | |
| 41 /* ------------------------------------------------------------------------- | |
| 42 Core mark/delete routines | |
| 43 ------------------------------------------------------------------------- */ | |
| 44 | |
| 45 /* True if we are invoked while the df engine is running; in this case, | |
| 46 we don't want to reenter it. */ | |
| 47 static bool df_in_progress = false; | |
| 48 | |
| 111 | 49 /* True if we are allowed to alter the CFG in this pass. */ |
| 50 static bool can_alter_cfg = false; | |
| 51 | |
| 0 | 52 /* Instructions that have been marked but whose dependencies have not |
| 53 yet been processed. */ | |
| 111 | 54 static vec<rtx_insn *> worklist; |
| 0 | 55 |
| 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. */ | |
| 60 static bitmap_obstack dce_blocks_bitmap_obstack; | |
| 61 static bitmap_obstack dce_tmp_bitmap_obstack; | |
| 62 | |
| 111 | 63 static bool find_call_stack_args (rtx_call_insn *, bool, bool, bitmap); |
| 0 | 64 |
| 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. */ | |
| 68 | |
| 69 static bool | |
| 70 deletable_insn_p_1 (rtx body) | |
| 71 { | |
| 72 switch (GET_CODE (body)) | |
| 73 { | |
| 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 | |
| 85 default: | |
|
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86 return !volatile_refs_p (body); |
| 0 | 87 } |
| 88 } | |
| 89 | |
| 145 | 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 } | |
| 0 | 116 |
| 117 /* Return true if INSN is a normal instruction that can be deleted by | |
| 118 the DCE pass. */ | |
| 119 | |
| 120 static bool | |
| 111 | 121 deletable_insn_p (rtx_insn *insn, bool fast, bitmap arg_stores) |
| 0 | 122 { |
| 123 rtx body, x; | |
| 124 int i; | |
| 111 | 125 df_ref def; |
| 0 | 126 |
| 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. */ | |
| 134 && (!SIBLING_CALL_P (insn)) | |
| 135 /* We can delete dead const or pure calls as long as they do not | |
| 136 infinite loop. */ | |
| 137 && (RTL_CONST_OR_PURE_CALL_P (insn) | |
| 145 | 138 && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)) |
| 139 /* Don't delete calls that may throw if we cannot do so. */ | |
| 140 && can_delete_call (insn)) | |
| 111 | 141 return find_call_stack_args (as_a <rtx_call_insn *> (insn), false, |
| 142 fast, arg_stores); | |
| 0 | 143 |
|
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144 /* Don't delete jumps, notes and the like. */ |
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145 if (!NONJUMP_INSN_P (insn)) |
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146 return false; |
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147 |
| 111 | 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)) | |
|
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151 return false; |
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152 |
| 111 | 153 /* If INSN sets a global_reg, leave it untouched. */ |
| 154 FOR_EACH_INSN_DEF (def, insn) | |
| 155 if (HARD_REGISTER_NUM_P (DF_REF_REGNO (def)) | |
| 156 && global_regs[DF_REF_REGNO (def)]) | |
| 157 return false; | |
| 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; | |
| 162 | |
| 131 | 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 | |
| 0 | 169 body = PATTERN (insn); |
| 170 switch (GET_CODE (body)) | |
| 171 { | |
| 172 case USE: | |
|
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173 case VAR_LOCATION: |
| 0 | 174 return false; |
| 175 | |
| 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. */ | |
| 182 x = XEXP (body, 0); | |
| 183 return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed); | |
| 184 } | |
| 185 else | |
| 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 | |
| 191 case PARALLEL: | |
| 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; | |
| 196 | |
| 197 default: | |
| 198 return deletable_insn_p_1 (body); | |
| 199 } | |
| 200 } | |
| 201 | |
| 202 | |
| 203 /* Return true if INSN has been marked as needed. */ | |
| 204 | |
| 205 static inline int | |
| 111 | 206 marked_insn_p (rtx_insn *insn) |
| 0 | 207 { |
| 208 /* Artificial defs are always needed and they do not have an insn. | |
| 209 We should never see them here. */ | |
| 210 gcc_assert (insn); | |
| 111 | 211 return bitmap_bit_p (marked, INSN_UID (insn)); |
| 0 | 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 | |
| 111 | 219 mark_insn (rtx_insn *insn, bool fast) |
| 0 | 220 { |
| 221 if (!marked_insn_p (insn)) | |
| 222 { | |
| 223 if (!fast) | |
| 111 | 224 worklist.safe_push (insn); |
| 225 bitmap_set_bit (marked, INSN_UID (insn)); | |
| 0 | 226 if (dump_file) |
| 227 fprintf (dump_file, " Adding insn %d to worklist\n", INSN_UID (insn)); | |
| 228 if (CALL_P (insn) | |
| 229 && !df_in_progress | |
| 230 && !SIBLING_CALL_P (insn) | |
| 231 && (RTL_CONST_OR_PURE_CALL_P (insn) | |
| 145 | 232 && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)) |
| 233 && can_delete_call (insn)) | |
| 111 | 234 find_call_stack_args (as_a <rtx_call_insn *> (insn), true, fast, NULL); |
| 0 | 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 | |
| 243 mark_nonreg_stores_1 (rtx dest, const_rtx pattern, void *data) | |
| 244 { | |
| 245 if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
| 145 | 246 mark_insn ((rtx_insn *) data, true); |
| 0 | 247 } |
| 248 | |
| 249 | |
| 250 /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
| 251 instruction containing DEST. */ | |
| 252 | |
| 253 static void | |
| 254 mark_nonreg_stores_2 (rtx dest, const_rtx pattern, void *data) | |
| 255 { | |
| 256 if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
| 145 | 257 mark_insn ((rtx_insn *) data, false); |
| 0 | 258 } |
| 259 | |
| 260 | |
| 145 | 261 /* Mark INSN if it stores to a non-register destination. */ |
| 0 | 262 |
| 263 static void | |
| 145 | 264 mark_nonreg_stores (rtx_insn *insn, bool fast) |
| 0 | 265 { |
| 266 if (fast) | |
| 145 | 267 note_stores (insn, mark_nonreg_stores_1, insn); |
| 0 | 268 else |
| 145 | 269 note_stores (insn, mark_nonreg_stores_2, insn); |
| 0 | 270 } |
| 271 | |
| 272 | |
| 111 | 273 /* Return true if a store to SIZE bytes, starting OFF bytes from stack pointer, |
|
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274 is a call argument store, and clear corresponding bits from SP_BYTES |
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275 bitmap if it is. */ |
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276 |
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277 static bool |
| 111 | 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) | |
|
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281 { |
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282 HOST_WIDE_INT byte; |
| 111 | 283 for (byte = off; byte < off + size; byte++) |
|
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284 { |
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285 if (byte < min_sp_off |
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286 || byte >= max_sp_off |
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287 || !bitmap_clear_bit (sp_bytes, byte - min_sp_off)) |
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288 return false; |
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289 } |
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290 return true; |
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291 } |
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292 |
| 145 | 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 } | |
| 345 | |
| 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 } | |
|
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nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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diff
changeset
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387 |
| 0 | 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 | |
| 111 | 396 find_call_stack_args (rtx_call_insn *call_insn, bool do_mark, bool fast, |
| 0 | 397 bitmap arg_stores) |
| 398 { | |
| 111 | 399 rtx p; |
| 400 rtx_insn *insn, *prev_insn; | |
| 0 | 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 { | |
| 145 | 424 rtx mem = XEXP (XEXP (p, 0), 0); |
| 425 HOST_WIDE_INT size; | |
| 131 | 426 if (!MEM_SIZE_KNOWN_P (mem) || !MEM_SIZE (mem).is_constant (&size)) |
| 111 | 427 return false; |
| 145 | 428 HOST_WIDE_INT off = sp_based_mem_offset (call_insn, mem, fast); |
| 429 if (off == INTTYPE_MINIMUM (HOST_WIDE_INT)) | |
| 430 return false; | |
| 0 | 431 min_sp_off = MIN (min_sp_off, off); |
| 111 | 432 max_sp_off = MAX (max_sp_off, off + size); |
| 0 | 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 { | |
| 145 | 446 rtx mem = XEXP (XEXP (p, 0), 0); |
| 131 | 447 /* Checked in the previous iteration. */ |
| 145 | 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 (); | |
| 0 | 454 } |
| 455 | |
| 456 /* Walk backwards, looking for argument stores. The search stops | |
| 145 | 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 }; | |
| 0 | 461 ret = false; |
| 462 for (insn = PREV_INSN (call_insn); insn; insn = prev_insn) | |
| 463 { | |
| 464 if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn))) | |
| 111 | 465 prev_insn = NULL; |
| 0 | 466 else |
| 467 prev_insn = PREV_INSN (insn); | |
| 468 | |
| 469 if (CALL_P (insn)) | |
| 470 break; | |
| 471 | |
|
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472 if (!NONDEBUG_INSN_P (insn)) |
| 0 | 473 continue; |
| 474 | |
| 145 | 475 rtx set = single_set (insn); |
| 0 | 476 if (!set || SET_DEST (set) == stack_pointer_rtx) |
| 477 break; | |
| 478 | |
| 145 | 479 note_uses (&PATTERN (insn), check_argument_load, &data); |
| 480 if (data.load_found) | |
| 481 break; | |
| 482 | |
| 0 | 483 if (!MEM_P (SET_DEST (set))) |
| 484 continue; | |
| 485 | |
| 145 | 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; | |
| 0 | 490 |
| 131 | 491 HOST_WIDE_INT size; |
| 111 | 492 if (!MEM_SIZE_KNOWN_P (mem) |
| 131 | 493 || !MEM_SIZE (mem).is_constant (&size) |
| 494 || !check_argument_store (size, off, min_sp_off, | |
|
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495 max_sp_off, sp_bytes)) |
| 0 | 496 break; |
| 497 | |
| 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 | |
|
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521 /* Remove all REG_EQUAL and REG_EQUIV notes referring to the registers INSN |
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522 writes to. */ |
| 0 | 523 |
| 524 static void | |
| 111 | 525 remove_reg_equal_equiv_notes_for_defs (rtx_insn *insn) |
| 0 | 526 { |
| 111 | 527 df_ref def; |
|
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528 |
| 111 | 529 FOR_EACH_INSN_DEF (def, insn) |
| 530 remove_reg_equal_equiv_notes_for_regno (DF_REF_REGNO (def)); | |
| 0 | 531 } |
| 532 | |
| 111 | 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; | |
| 540 rtx_insn *insn, *next; | |
| 541 | |
| 542 FOR_EACH_BB_REVERSE_FN (bb, cfun) | |
| 543 FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) | |
| 544 if (DEBUG_INSN_P (insn)) | |
| 545 { | |
| 546 df_ref use; | |
| 547 | |
| 548 FOR_EACH_INSN_USE (use, insn) | |
| 549 { | |
| 550 struct df_link *defs; | |
| 551 for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
| 552 { | |
| 553 rtx_insn *ref_insn; | |
| 554 if (DF_REF_IS_ARTIFICIAL (defs->ref)) | |
| 555 continue; | |
| 556 ref_insn = DF_REF_INSN (defs->ref); | |
| 557 if (!marked_insn_p (ref_insn)) | |
| 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); | |
| 566 break; | |
| 567 } | |
| 568 } | |
| 569 } | |
| 0 | 570 |
| 571 /* Delete every instruction that hasn't been marked. */ | |
| 572 | |
| 573 static void | |
| 574 delete_unmarked_insns (void) | |
| 575 { | |
| 576 basic_block bb; | |
| 111 | 577 rtx_insn *insn, *next; |
| 0 | 578 bool must_clean = false; |
| 579 | |
| 111 | 580 FOR_EACH_BB_REVERSE_FN (bb, cfun) |
| 0 | 581 FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
| 111 | 582 if (NONDEBUG_INSN_P (insn)) |
| 0 | 583 { |
| 131 | 584 rtx turn_into_use = NULL_RTX; |
| 585 | |
| 0 | 586 /* Always delete no-op moves. */ |
| 145 | 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))) | |
| 131 | 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 } | |
| 0 | 602 |
| 603 /* Otherwise rely only on the DCE algorithm. */ | |
| 604 else if (marked_insn_p (insn)) | |
| 605 continue; | |
| 606 | |
| 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. */ | |
| 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 | |
|
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631 /* Before we delete the insn we have to remove the REG_EQUAL notes |
| 0 | 632 for the destination regs in order to avoid dangling notes. */ |
|
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633 remove_reg_equal_equiv_notes_for_defs (insn); |
| 0 | 634 |
| 131 | 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. */ | |
| 145 | 647 must_clean |= delete_insn_and_edges (insn); |
| 0 | 648 } |
| 649 | |
| 650 /* Deleted a pure or const call. */ | |
| 651 if (must_clean) | |
| 145 | 652 { |
| 653 gcc_assert (can_alter_cfg); | |
| 654 delete_unreachable_blocks (); | |
| 655 free_dominance_info (CDI_DOMINATORS); | |
| 656 } | |
| 0 | 657 } |
| 658 | |
| 659 | |
| 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; | |
| 111 | 668 rtx_insn *insn, *prev; |
| 0 | 669 bitmap arg_stores = NULL; |
| 670 | |
| 671 if (dump_file) | |
| 672 fprintf (dump_file, "Finding needed instructions:\n"); | |
| 673 | |
| 674 if (!df_in_progress && ACCUMULATE_OUTGOING_ARGS) | |
| 675 arg_stores = BITMAP_ALLOC (NULL); | |
| 676 | |
| 111 | 677 FOR_EACH_BB_FN (bb, cfun) |
| 0 | 678 { |
| 679 FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev) | |
| 111 | 680 if (NONDEBUG_INSN_P (insn)) |
| 0 | 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)) | |
| 145 | 687 mark_nonreg_stores (insn, fast); |
| 0 | 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); | |
| 699 | |
| 700 if (dump_file) | |
| 701 fprintf (dump_file, "Finished finding needed instructions:\n"); | |
| 702 } | |
| 703 | |
| 704 | |
| 705 /* UD-based DSE routines. */ | |
| 706 | |
| 707 /* Mark instructions that define artificially-used registers, such as | |
| 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; | |
| 111 | 715 df_ref use; |
| 0 | 716 |
| 111 | 717 FOR_ALL_BB_FN (bb, cfun) |
| 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); | |
| 0 | 722 } |
| 723 | |
| 724 | |
| 725 /* Mark every instruction that defines a register value that INSN uses. */ | |
| 726 | |
| 727 static void | |
| 111 | 728 mark_reg_dependencies (rtx_insn *insn) |
| 0 | 729 { |
| 730 struct df_link *defs; | |
| 111 | 731 df_ref use; |
| 0 | 732 |
|
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733 if (DEBUG_INSN_P (insn)) |
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734 return; |
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735 |
| 111 | 736 FOR_EACH_INSN_USE (use, insn) |
| 0 | 737 { |
| 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) | |
| 745 if (! DF_REF_IS_ARTIFICIAL (defs->ref)) | |
| 746 mark_insn (DF_REF_INSN (defs->ref), false); | |
| 747 } | |
| 748 } | |
| 749 | |
| 750 | |
| 751 /* Initialize global variables for a new DCE pass. */ | |
| 752 | |
| 753 static void | |
| 754 init_dce (bool fast) | |
| 755 { | |
| 756 if (!df_in_progress) | |
| 757 { | |
| 758 if (!fast) | |
| 111 | 759 { |
| 760 df_set_flags (DF_RD_PRUNE_DEAD_DEFS); | |
| 761 df_chain_add_problem (DF_UD_CHAIN); | |
| 762 } | |
| 0 | 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); | |
| 111 | 773 can_alter_cfg = false; |
| 0 | 774 } |
| 111 | 775 else |
| 776 can_alter_cfg = true; | |
| 0 | 777 |
| 778 marked = sbitmap_alloc (get_max_uid () + 1); | |
| 111 | 779 bitmap_clear (marked); |
| 0 | 780 } |
| 781 | |
| 782 | |
| 783 /* Free the data allocated by init_dce. */ | |
| 784 | |
| 785 static void | |
| 786 fini_dce (bool fast) | |
| 787 { | |
| 788 sbitmap_free (marked); | |
| 789 | |
| 790 if (fast) | |
| 791 { | |
| 792 bitmap_obstack_release (&dce_blocks_bitmap_obstack); | |
| 793 bitmap_obstack_release (&dce_tmp_bitmap_obstack); | |
| 794 } | |
| 795 } | |
| 796 | |
| 797 | |
| 798 /* UD-chain based DCE. */ | |
| 799 | |
| 800 static unsigned int | |
| 801 rest_of_handle_ud_dce (void) | |
| 802 { | |
| 111 | 803 rtx_insn *insn; |
| 0 | 804 |
| 805 init_dce (false); | |
| 806 | |
| 807 prescan_insns_for_dce (false); | |
| 808 mark_artificial_uses (); | |
| 111 | 809 while (worklist.length () > 0) |
| 0 | 810 { |
| 111 | 811 insn = worklist.pop (); |
| 0 | 812 mark_reg_dependencies (insn); |
| 813 } | |
| 111 | 814 worklist.release (); |
| 815 | |
| 131 | 816 if (MAY_HAVE_DEBUG_BIND_INSNS) |
| 111 | 817 reset_unmarked_insns_debug_uses (); |
| 0 | 818 |
| 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 | |
| 824 fini_dce (false); | |
| 825 return 0; | |
| 826 } | |
| 827 | |
| 828 | |
| 111 | 829 namespace { |
| 830 | |
| 831 const pass_data pass_data_ud_rtl_dce = | |
| 0 | 832 { |
| 111 | 833 RTL_PASS, /* type */ |
| 834 "ud_dce", /* name */ | |
| 835 OPTGROUP_NONE, /* optinfo_flags */ | |
| 836 TV_DCE, /* tv_id */ | |
| 837 0, /* properties_required */ | |
| 838 0, /* properties_provided */ | |
| 839 0, /* properties_destroyed */ | |
| 840 0, /* todo_flags_start */ | |
| 841 TODO_df_finish, /* todo_flags_finish */ | |
| 842 }; | |
| 0 | 843 |
| 111 | 844 class pass_ud_rtl_dce : public rtl_opt_pass |
| 0 | 845 { |
| 111 | 846 public: |
| 847 pass_ud_rtl_dce (gcc::context *ctxt) | |
| 848 : rtl_opt_pass (pass_data_ud_rtl_dce, ctxt) | |
| 849 {} | |
| 850 | |
| 851 /* opt_pass methods: */ | |
| 852 virtual bool gate (function *) | |
| 853 { | |
| 854 return optimize > 1 && flag_dce && dbg_cnt (dce_ud); | |
| 855 } | |
| 856 | |
| 857 virtual unsigned int execute (function *) | |
| 858 { | |
| 859 return rest_of_handle_ud_dce (); | |
| 860 } | |
| 861 | |
| 862 }; // class pass_ud_rtl_dce | |
| 863 | |
| 864 } // anon namespace | |
| 865 | |
| 866 rtl_opt_pass * | |
| 867 make_pass_ud_rtl_dce (gcc::context *ctxt) | |
| 868 { | |
| 869 return new pass_ud_rtl_dce (ctxt); | |
| 870 } | |
| 0 | 871 |
| 872 | |
| 873 /* ------------------------------------------------------------------------- | |
| 874 Fast DCE functions | |
| 875 ------------------------------------------------------------------------- */ | |
| 876 | |
| 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 | |
| 111 | 880 artificial uses. Track global substitution of uses of dead pseudos |
| 881 in debug insns using GLOBAL_DEBUG. */ | |
| 0 | 882 |
| 883 static bool | |
| 111 | 884 word_dce_process_block (basic_block bb, bool redo_out, |
| 885 struct dead_debug_global *global_debug) | |
| 0 | 886 { |
| 887 bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
| 111 | 888 rtx_insn *insn; |
| 0 | 889 bool block_changed; |
| 111 | 890 struct dead_debug_local debug; |
| 0 | 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; | |
|
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899 df_confluence_function_n con_fun_n = df_word_lr->problem->con_fun_n; |
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900 bitmap_clear (DF_WORD_LR_OUT (bb)); |
| 0 | 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); | |
|
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908 df_print_word_regset (dump_file, DF_WORD_LR_OUT (bb)); |
| 0 | 909 } |
| 910 | |
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911 bitmap_copy (local_live, DF_WORD_LR_OUT (bb)); |
| 111 | 912 dead_debug_local_init (&debug, NULL, global_debug); |
| 0 | 913 |
| 914 FOR_BB_INSNS_REVERSE (bb, insn) | |
| 111 | 915 if (DEBUG_INSN_P (insn)) |
| 916 { | |
| 917 df_ref use; | |
| 918 FOR_EACH_INSN_USE (use, insn) | |
| 919 if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER | |
| 131 | 920 && known_eq (GET_MODE_SIZE (GET_MODE (DF_REF_REAL_REG (use))), |
| 921 2 * UNITS_PER_WORD) | |
| 111 | 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)); | |
| 925 } | |
| 926 else if (INSN_P (insn)) | |
| 0 | 927 { |
|
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928 bool any_changed; |
| 111 | 929 |
| 0 | 930 /* No matter if the instruction is needed or not, we remove |
| 931 any regno in the defs from the live set. */ | |
|
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932 any_changed = df_word_lr_simulate_defs (insn, local_live); |
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933 if (any_changed) |
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934 mark_insn (insn, true); |
| 0 | 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)) | |
|
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939 df_word_lr_simulate_uses (insn, local_live); |
| 0 | 940 |
| 111 | 941 /* Insert debug temps for dead REGs used in subsequent debug |
| 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)) | |
| 946 { | |
| 947 df_ref def; | |
| 948 | |
| 949 FOR_EACH_INSN_DEF (def, insn) | |
| 950 dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
| 951 marked_insn_p (insn) | |
| 952 && !control_flow_insn_p (insn) | |
| 953 ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
| 954 : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
| 955 } | |
| 956 | |
| 0 | 957 if (dump_file) |
| 958 { | |
|
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959 fprintf (dump_file, "finished processing insn %d live out = ", |
| 0 | 960 INSN_UID (insn)); |
|
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961 df_print_word_regset (dump_file, local_live); |
| 0 | 962 } |
| 963 } | |
|
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964 |
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965 block_changed = !bitmap_equal_p (local_live, DF_WORD_LR_IN (bb)); |
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966 if (block_changed) |
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967 bitmap_copy (DF_WORD_LR_IN (bb), local_live); |
| 0 | 968 |
| 111 | 969 dead_debug_local_finish (&debug, NULL); |
| 0 | 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 | |
| 111 | 978 artificial uses. Track global substitution of uses of dead pseudos |
| 979 in debug insns using GLOBAL_DEBUG. */ | |
| 0 | 980 |
| 981 static bool | |
| 111 | 982 dce_process_block (basic_block bb, bool redo_out, bitmap au, |
| 983 struct dead_debug_global *global_debug) | |
| 0 | 984 { |
| 985 bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
| 111 | 986 rtx_insn *insn; |
| 0 | 987 bool block_changed; |
| 111 | 988 df_ref def; |
| 989 struct dead_debug_local debug; | |
| 0 | 990 |
| 991 if (redo_out) | |
| 992 { | |
| 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); | |
| 1002 } | |
| 1003 | |
| 1004 if (dump_file) | |
| 1005 { | |
| 1006 fprintf (dump_file, "processing block %d lr out = ", bb->index); | |
| 1007 df_print_regset (dump_file, DF_LR_OUT (bb)); | |
| 1008 } | |
| 1009 | |
| 1010 bitmap_copy (local_live, DF_LR_OUT (bb)); | |
| 1011 | |
| 1012 df_simulate_initialize_backwards (bb, local_live); | |
| 111 | 1013 dead_debug_local_init (&debug, NULL, global_debug); |
| 0 | 1014 |
| 1015 FOR_BB_INSNS_REVERSE (bb, insn) | |
| 111 | 1016 if (DEBUG_INSN_P (insn)) |
| 1017 { | |
| 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)); | |
| 1023 } | |
| 1024 else if (INSN_P (insn)) | |
| 0 | 1025 { |
|
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1026 bool needed = marked_insn_p (insn); |
| 0 | 1027 |
| 1028 /* The insn is needed if there is someone who uses the output. */ | |
|
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1029 if (!needed) |
| 111 | 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))) | |
|
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1033 { |
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1034 needed = true; |
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1035 mark_insn (insn, true); |
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1036 break; |
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1037 } |
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1038 |
| 0 | 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. */ | |
|
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1045 if (needed) |
| 0 | 1046 df_simulate_uses (insn, local_live); |
| 111 | 1047 |
| 1048 /* Insert debug temps for dead REGs used in subsequent debug | |
| 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)) | |
| 1053 FOR_EACH_INSN_DEF (def, insn) | |
| 1054 dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
| 1055 needed && !control_flow_insn_p (insn) | |
| 1056 ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
| 1057 : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
| 0 | 1058 } |
|
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1059 |
| 111 | 1060 dead_debug_local_finish (&debug, NULL); |
| 0 | 1061 df_simulate_finalize_backwards (bb, local_live); |
| 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 | |
| 1071 | |
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1072 /* Perform fast DCE once initialization is done. If WORD_LEVEL is |
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1073 true, use the word level dce, otherwise do it at the pseudo |
| 0 | 1074 level. */ |
| 1075 | |
| 1076 static void | |
|
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1077 fast_dce (bool word_level) |
| 0 | 1078 { |
| 1079 int *postorder = df_get_postorder (DF_BACKWARD); | |
| 1080 int n_blocks = df_get_n_blocks (DF_BACKWARD); | |
| 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; | |
| 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. */ | |
|
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1094 bitmap au = &df->regular_block_artificial_uses; |
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1095 bitmap au_eh = &df->eh_block_artificial_uses; |
| 0 | 1096 int i; |
| 111 | 1097 struct dead_debug_global global_debug; |
| 0 | 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 | |
| 111 | 1104 dead_debug_global_init (&global_debug, NULL); |
| 1105 | |
| 0 | 1106 while (global_changed) |
| 1107 { | |
| 1108 global_changed = false; | |
| 1109 | |
| 1110 for (i = 0; i < n_blocks; i++) | |
| 1111 { | |
| 1112 int index = postorder[i]; | |
| 111 | 1113 basic_block bb = BASIC_BLOCK_FOR_FN (cfun, index); |
| 0 | 1114 bool local_changed; |
| 1115 | |
| 1116 if (index < NUM_FIXED_BLOCKS) | |
| 1117 { | |
| 1118 bitmap_set_bit (processed, index); | |
| 1119 continue; | |
| 1120 } | |
| 1121 | |
|
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1122 if (word_level) |
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1123 local_changed |
| 111 | 1124 = word_dce_process_block (bb, bitmap_bit_p (redo_out, index), |
| 1125 &global_debug); | |
| 0 | 1126 else |
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1127 local_changed |
| 0 | 1128 = dce_process_block (bb, bitmap_bit_p (redo_out, index), |
| 111 | 1129 bb_has_eh_pred (bb) ? au_eh : au, |
| 1130 &global_debug); | |
| 0 | 1131 bitmap_set_bit (processed, index); |
|
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1132 |
| 0 | 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 } | |
|
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1148 |
| 0 | 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 (); | |
| 111 | 1158 bitmap_clear (marked); |
| 0 | 1159 bitmap_clear (processed); |
| 1160 bitmap_clear (redo_out); | |
|
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1161 |
| 0 | 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 | |
|
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1165 iteration. */ |
|
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1166 if (word_level) |
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1167 df_analyze_problem (df_word_lr, all_blocks, postorder, n_blocks); |
| 0 | 1168 else |
| 1169 df_analyze_problem (df_lr, all_blocks, postorder, n_blocks); | |
| 1170 | |
| 1171 if (old_flag & DF_LR_RUN_DCE) | |
| 1172 df_set_flags (DF_LR_RUN_DCE); | |
| 1173 | |
| 1174 prescan_insns_for_dce (true); | |
| 1175 } | |
| 1176 } | |
| 1177 | |
| 111 | 1178 dead_debug_global_finish (&global_debug, NULL); |
| 1179 | |
| 0 | 1180 delete_unmarked_insns (); |
| 1181 | |
| 1182 BITMAP_FREE (processed); | |
| 1183 BITMAP_FREE (redo_out); | |
| 1184 BITMAP_FREE (all_blocks); | |
| 1185 } | |
| 1186 | |
| 1187 | |
| 1188 /* Fast register level DCE. */ | |
| 1189 | |
| 1190 static unsigned int | |
| 1191 rest_of_handle_fast_dce (void) | |
| 1192 { | |
| 1193 init_dce (true); | |
| 1194 fast_dce (false); | |
| 1195 fini_dce (true); | |
| 1196 return 0; | |
| 1197 } | |
| 1198 | |
| 1199 | |
| 1200 /* Fast byte level DCE. */ | |
| 1201 | |
|
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1202 void |
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1203 run_word_dce (void) |
| 0 | 1204 { |
|
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1205 int old_flags; |
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1206 |
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1207 if (!flag_dce) |
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1208 return; |
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1209 |
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1210 timevar_push (TV_DCE); |
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1211 old_flags = df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
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1212 df_word_lr_add_problem (); |
| 0 | 1213 init_dce (true); |
| 1214 fast_dce (true); | |
| 1215 fini_dce (true); | |
|
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1216 df_set_flags (old_flags); |
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parents:
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1217 timevar_pop (TV_DCE); |
| 0 | 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 | |
| 1228 vectors for any other problems than LR. */ | |
| 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. */ | |
|
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1238 int old_flags = |
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1239 df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
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1240 |
| 0 | 1241 df_in_progress = true; |
| 1242 rest_of_handle_fast_dce (); | |
| 1243 df_in_progress = false; | |
| 1244 | |
| 1245 df_set_flags (old_flags); | |
| 1246 } | |
| 1247 } | |
| 1248 | |
| 1249 | |
| 1250 /* Run a fast DCE pass. */ | |
| 1251 | |
| 1252 void | |
| 1253 run_fast_dce (void) | |
| 1254 { | |
| 1255 if (flag_dce) | |
| 1256 rest_of_handle_fast_dce (); | |
| 1257 } | |
| 1258 | |
| 1259 | |
| 111 | 1260 namespace { |
| 1261 | |
| 1262 const pass_data pass_data_fast_rtl_dce = | |
| 0 | 1263 { |
| 111 | 1264 RTL_PASS, /* type */ |
| 1265 "rtl_dce", /* name */ | |
| 1266 OPTGROUP_NONE, /* optinfo_flags */ | |
| 1267 TV_DCE, /* tv_id */ | |
| 1268 0, /* properties_required */ | |
| 1269 0, /* properties_provided */ | |
| 1270 0, /* properties_destroyed */ | |
| 1271 0, /* todo_flags_start */ | |
| 1272 TODO_df_finish, /* todo_flags_finish */ | |
| 1273 }; | |
| 0 | 1274 |
| 111 | 1275 class pass_fast_rtl_dce : public rtl_opt_pass |
| 0 | 1276 { |
| 111 | 1277 public: |
| 1278 pass_fast_rtl_dce (gcc::context *ctxt) | |
| 1279 : rtl_opt_pass (pass_data_fast_rtl_dce, ctxt) | |
| 1280 {} | |
| 1281 | |
| 1282 /* opt_pass methods: */ | |
| 1283 virtual bool gate (function *) | |
| 1284 { | |
| 1285 return optimize > 0 && flag_dce && dbg_cnt (dce_fast); | |
| 1286 } | |
| 1287 | |
| 1288 virtual unsigned int execute (function *) | |
| 1289 { | |
| 1290 return rest_of_handle_fast_dce (); | |
| 1291 } | |
| 1292 | |
| 1293 }; // class pass_fast_rtl_dce | |
| 1294 | |
| 1295 } // anon namespace | |
| 1296 | |
| 1297 rtl_opt_pass * | |
| 1298 make_pass_fast_rtl_dce (gcc::context *ctxt) | |
| 1299 { | |
| 1300 return new pass_fast_rtl_dce (ctxt); | |
| 1301 } |