Mercurial > hg > CbC > CbC_gcc
annotate gcc/dce.c @ 111:04ced10e8804
gcc 7
| author | kono |
|---|---|
| date | Fri, 27 Oct 2017 22:46:09 +0900 |
| parents | f6334be47118 |
| children | 84e7813d76e9 |
| rev | line source |
|---|---|
| 0 | 1 /* RTL dead code elimination. |
| 111 | 2 Copyright (C) 2005-2017 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" | |
| 38 | |
| 39 | |
| 40 /* ------------------------------------------------------------------------- | |
| 41 Core mark/delete routines | |
| 42 ------------------------------------------------------------------------- */ | |
| 43 | |
| 44 /* True if we are invoked while the df engine is running; in this case, | |
| 45 we don't want to reenter it. */ | |
| 46 static bool df_in_progress = false; | |
| 47 | |
| 111 | 48 /* True if we are allowed to alter the CFG in this pass. */ |
| 49 static bool can_alter_cfg = false; | |
| 50 | |
| 0 | 51 /* Instructions that have been marked but whose dependencies have not |
| 52 yet been processed. */ | |
| 111 | 53 static vec<rtx_insn *> worklist; |
| 0 | 54 |
| 55 /* Bitmap of instructions marked as needed indexed by INSN_UID. */ | |
| 56 static sbitmap marked; | |
| 57 | |
| 58 /* Bitmap obstacks used for block processing by the fast algorithm. */ | |
| 59 static bitmap_obstack dce_blocks_bitmap_obstack; | |
| 60 static bitmap_obstack dce_tmp_bitmap_obstack; | |
| 61 | |
| 111 | 62 static bool find_call_stack_args (rtx_call_insn *, bool, bool, bitmap); |
| 0 | 63 |
| 64 /* A subroutine for which BODY is part of the instruction being tested; | |
| 65 either the top-level pattern, or an element of a PARALLEL. The | |
| 66 instruction is known not to be a bare USE or CLOBBER. */ | |
| 67 | |
| 68 static bool | |
| 69 deletable_insn_p_1 (rtx body) | |
| 70 { | |
| 71 switch (GET_CODE (body)) | |
| 72 { | |
| 73 case PREFETCH: | |
| 74 case TRAP_IF: | |
| 75 /* The UNSPEC case was added here because the ia-64 claims that | |
| 76 USEs do not work after reload and generates UNSPECS rather | |
| 77 than USEs. Since dce is run after reload we need to avoid | |
| 78 deleting these even if they are dead. If it turns out that | |
| 79 USEs really do work after reload, the ia-64 should be | |
| 80 changed, and the UNSPEC case can be removed. */ | |
| 81 case UNSPEC: | |
| 82 return false; | |
| 83 | |
| 84 default: | |
|
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85 return !volatile_refs_p (body); |
| 0 | 86 } |
| 87 } | |
| 88 | |
| 89 | |
| 90 /* Return true if INSN is a normal instruction that can be deleted by | |
| 91 the DCE pass. */ | |
| 92 | |
| 93 static bool | |
| 111 | 94 deletable_insn_p (rtx_insn *insn, bool fast, bitmap arg_stores) |
| 0 | 95 { |
| 96 rtx body, x; | |
| 97 int i; | |
| 111 | 98 df_ref def; |
| 0 | 99 |
| 100 if (CALL_P (insn) | |
| 101 /* We cannot delete calls inside of the recursive dce because | |
| 102 this may cause basic blocks to be deleted and this messes up | |
| 103 the rest of the stack of optimization passes. */ | |
| 104 && (!df_in_progress) | |
| 105 /* We cannot delete pure or const sibling calls because it is | |
| 106 hard to see the result. */ | |
| 107 && (!SIBLING_CALL_P (insn)) | |
| 108 /* We can delete dead const or pure calls as long as they do not | |
| 109 infinite loop. */ | |
| 110 && (RTL_CONST_OR_PURE_CALL_P (insn) | |
| 111 && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
| 111 | 112 return find_call_stack_args (as_a <rtx_call_insn *> (insn), false, |
| 113 fast, arg_stores); | |
| 0 | 114 |
|
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115 /* Don't delete jumps, notes and the like. */ |
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116 if (!NONJUMP_INSN_P (insn)) |
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117 return false; |
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118 |
| 111 | 119 /* Don't delete insns that may throw if we cannot do so. */ |
| 120 if (!(cfun->can_delete_dead_exceptions && can_alter_cfg) | |
| 121 && !insn_nothrow_p (insn)) | |
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122 return false; |
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123 |
| 111 | 124 /* If INSN sets a global_reg, leave it untouched. */ |
| 125 FOR_EACH_INSN_DEF (def, insn) | |
| 126 if (HARD_REGISTER_NUM_P (DF_REF_REGNO (def)) | |
| 127 && global_regs[DF_REF_REGNO (def)]) | |
| 128 return false; | |
| 129 /* Initialization of pseudo PIC register should never be removed. */ | |
| 130 else if (DF_REF_REG (def) == pic_offset_table_rtx | |
| 131 && REGNO (pic_offset_table_rtx) >= FIRST_PSEUDO_REGISTER) | |
| 132 return false; | |
| 133 | |
| 0 | 134 body = PATTERN (insn); |
| 135 switch (GET_CODE (body)) | |
| 136 { | |
| 137 case USE: | |
|
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138 case VAR_LOCATION: |
| 0 | 139 return false; |
| 140 | |
| 141 case CLOBBER: | |
| 142 if (fast) | |
| 143 { | |
| 144 /* A CLOBBER of a dead pseudo register serves no purpose. | |
| 145 That is not necessarily true for hard registers until | |
| 146 after reload. */ | |
| 147 x = XEXP (body, 0); | |
| 148 return REG_P (x) && (!HARD_REGISTER_P (x) || reload_completed); | |
| 149 } | |
| 150 else | |
| 151 /* Because of the way that use-def chains are built, it is not | |
| 152 possible to tell if the clobber is dead because it can | |
| 153 never be the target of a use-def chain. */ | |
| 154 return false; | |
| 155 | |
| 156 case PARALLEL: | |
| 157 for (i = XVECLEN (body, 0) - 1; i >= 0; i--) | |
| 158 if (!deletable_insn_p_1 (XVECEXP (body, 0, i))) | |
| 159 return false; | |
| 160 return true; | |
| 161 | |
| 162 default: | |
| 163 return deletable_insn_p_1 (body); | |
| 164 } | |
| 165 } | |
| 166 | |
| 167 | |
| 168 /* Return true if INSN has been marked as needed. */ | |
| 169 | |
| 170 static inline int | |
| 111 | 171 marked_insn_p (rtx_insn *insn) |
| 0 | 172 { |
| 173 /* Artificial defs are always needed and they do not have an insn. | |
| 174 We should never see them here. */ | |
| 175 gcc_assert (insn); | |
| 111 | 176 return bitmap_bit_p (marked, INSN_UID (insn)); |
| 0 | 177 } |
| 178 | |
| 179 | |
| 180 /* If INSN has not yet been marked as needed, mark it now, and add it to | |
| 181 the worklist. */ | |
| 182 | |
| 183 static void | |
| 111 | 184 mark_insn (rtx_insn *insn, bool fast) |
| 0 | 185 { |
| 186 if (!marked_insn_p (insn)) | |
| 187 { | |
| 188 if (!fast) | |
| 111 | 189 worklist.safe_push (insn); |
| 190 bitmap_set_bit (marked, INSN_UID (insn)); | |
| 0 | 191 if (dump_file) |
| 192 fprintf (dump_file, " Adding insn %d to worklist\n", INSN_UID (insn)); | |
| 193 if (CALL_P (insn) | |
| 194 && !df_in_progress | |
| 195 && !SIBLING_CALL_P (insn) | |
| 196 && (RTL_CONST_OR_PURE_CALL_P (insn) | |
| 197 && !RTL_LOOPING_CONST_OR_PURE_CALL_P (insn))) | |
| 111 | 198 find_call_stack_args (as_a <rtx_call_insn *> (insn), true, fast, NULL); |
| 0 | 199 } |
| 200 } | |
| 201 | |
| 202 | |
| 203 /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
| 204 instruction containing DEST. */ | |
| 205 | |
| 206 static void | |
| 207 mark_nonreg_stores_1 (rtx dest, const_rtx pattern, void *data) | |
| 208 { | |
| 209 if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
| 111 | 210 mark_insn ((rtx_insn *) data, true); |
| 0 | 211 } |
| 212 | |
| 213 | |
| 214 /* A note_stores callback used by mark_nonreg_stores. DATA is the | |
| 215 instruction containing DEST. */ | |
| 216 | |
| 217 static void | |
| 218 mark_nonreg_stores_2 (rtx dest, const_rtx pattern, void *data) | |
| 219 { | |
| 220 if (GET_CODE (pattern) != CLOBBER && !REG_P (dest)) | |
| 111 | 221 mark_insn ((rtx_insn *) data, false); |
| 0 | 222 } |
| 223 | |
| 224 | |
| 225 /* Mark INSN if BODY stores to a non-register destination. */ | |
| 226 | |
| 227 static void | |
| 111 | 228 mark_nonreg_stores (rtx body, rtx_insn *insn, bool fast) |
| 0 | 229 { |
| 230 if (fast) | |
| 231 note_stores (body, mark_nonreg_stores_1, insn); | |
| 232 else | |
| 233 note_stores (body, mark_nonreg_stores_2, insn); | |
| 234 } | |
| 235 | |
| 236 | |
| 111 | 237 /* Return true if a store to SIZE bytes, starting OFF bytes from stack pointer, |
|
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238 is a call argument store, and clear corresponding bits from SP_BYTES |
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239 bitmap if it is. */ |
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240 |
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241 static bool |
| 111 | 242 check_argument_store (HOST_WIDE_INT size, HOST_WIDE_INT off, |
| 243 HOST_WIDE_INT min_sp_off, HOST_WIDE_INT max_sp_off, | |
| 244 bitmap sp_bytes) | |
|
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245 { |
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246 HOST_WIDE_INT byte; |
| 111 | 247 for (byte = off; byte < off + size; byte++) |
|
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248 { |
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249 if (byte < min_sp_off |
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250 || byte >= max_sp_off |
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251 || !bitmap_clear_bit (sp_bytes, byte - min_sp_off)) |
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252 return false; |
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253 } |
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254 return true; |
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255 } |
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256 |
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257 |
| 0 | 258 /* Try to find all stack stores of CALL_INSN arguments if |
| 259 ACCUMULATE_OUTGOING_ARGS. If all stack stores have been found | |
| 260 and it is therefore safe to eliminate the call, return true, | |
| 261 otherwise return false. This function should be first called | |
| 262 with DO_MARK false, and only when the CALL_INSN is actually | |
| 263 going to be marked called again with DO_MARK true. */ | |
| 264 | |
| 265 static bool | |
| 111 | 266 find_call_stack_args (rtx_call_insn *call_insn, bool do_mark, bool fast, |
| 0 | 267 bitmap arg_stores) |
| 268 { | |
| 111 | 269 rtx p; |
| 270 rtx_insn *insn, *prev_insn; | |
| 0 | 271 bool ret; |
| 272 HOST_WIDE_INT min_sp_off, max_sp_off; | |
| 273 bitmap sp_bytes; | |
| 274 | |
| 275 gcc_assert (CALL_P (call_insn)); | |
| 276 if (!ACCUMULATE_OUTGOING_ARGS) | |
| 277 return true; | |
| 278 | |
| 279 if (!do_mark) | |
| 280 { | |
| 281 gcc_assert (arg_stores); | |
| 282 bitmap_clear (arg_stores); | |
| 283 } | |
| 284 | |
| 285 min_sp_off = INTTYPE_MAXIMUM (HOST_WIDE_INT); | |
| 286 max_sp_off = 0; | |
| 287 | |
| 288 /* First determine the minimum and maximum offset from sp for | |
| 289 stored arguments. */ | |
| 290 for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
| 291 if (GET_CODE (XEXP (p, 0)) == USE | |
| 292 && MEM_P (XEXP (XEXP (p, 0), 0))) | |
| 293 { | |
| 111 | 294 rtx mem = XEXP (XEXP (p, 0), 0), addr; |
| 295 HOST_WIDE_INT off = 0, size; | |
| 296 if (!MEM_SIZE_KNOWN_P (mem)) | |
| 297 return false; | |
| 0 | 298 size = MEM_SIZE (mem); |
| 299 addr = XEXP (mem, 0); | |
| 300 if (GET_CODE (addr) == PLUS | |
| 301 && REG_P (XEXP (addr, 0)) | |
| 302 && CONST_INT_P (XEXP (addr, 1))) | |
| 303 { | |
| 304 off = INTVAL (XEXP (addr, 1)); | |
| 305 addr = XEXP (addr, 0); | |
| 306 } | |
| 307 if (addr != stack_pointer_rtx) | |
| 308 { | |
| 309 if (!REG_P (addr)) | |
| 310 return false; | |
| 311 /* If not fast, use chains to see if addr wasn't set to | |
| 312 sp + offset. */ | |
| 313 if (!fast) | |
| 314 { | |
| 111 | 315 df_ref use; |
| 0 | 316 struct df_link *defs; |
| 317 rtx set; | |
| 318 | |
| 111 | 319 FOR_EACH_INSN_USE (use, call_insn) |
| 320 if (rtx_equal_p (addr, DF_REF_REG (use))) | |
| 0 | 321 break; |
| 322 | |
| 111 | 323 if (use == NULL) |
| 0 | 324 return false; |
| 325 | |
| 111 | 326 for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
| 0 | 327 if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
| 328 break; | |
| 329 | |
| 330 if (defs == NULL) | |
| 331 return false; | |
| 332 | |
| 333 set = single_set (DF_REF_INSN (defs->ref)); | |
| 334 if (!set) | |
| 335 return false; | |
| 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 false; | |
| 341 | |
| 342 off += INTVAL (XEXP (SET_SRC (set), 1)); | |
| 343 } | |
| 344 else | |
| 345 return false; | |
| 346 } | |
| 347 min_sp_off = MIN (min_sp_off, off); | |
| 111 | 348 max_sp_off = MAX (max_sp_off, off + size); |
| 0 | 349 } |
| 350 | |
| 351 if (min_sp_off >= max_sp_off) | |
| 352 return true; | |
| 353 sp_bytes = BITMAP_ALLOC (NULL); | |
| 354 | |
| 355 /* Set bits in SP_BYTES bitmap for bytes relative to sp + min_sp_off | |
| 356 which contain arguments. Checking has been done in the previous | |
| 357 loop. */ | |
| 358 for (p = CALL_INSN_FUNCTION_USAGE (call_insn); p; p = XEXP (p, 1)) | |
| 359 if (GET_CODE (XEXP (p, 0)) == USE | |
| 360 && MEM_P (XEXP (XEXP (p, 0), 0))) | |
| 361 { | |
| 362 rtx mem = XEXP (XEXP (p, 0), 0), addr; | |
| 363 HOST_WIDE_INT off = 0, byte; | |
| 364 addr = XEXP (mem, 0); | |
| 365 if (GET_CODE (addr) == PLUS | |
| 366 && REG_P (XEXP (addr, 0)) | |
| 367 && CONST_INT_P (XEXP (addr, 1))) | |
| 368 { | |
| 369 off = INTVAL (XEXP (addr, 1)); | |
| 370 addr = XEXP (addr, 0); | |
| 371 } | |
| 372 if (addr != stack_pointer_rtx) | |
| 373 { | |
| 111 | 374 df_ref use; |
| 0 | 375 struct df_link *defs; |
| 376 rtx set; | |
| 377 | |
| 111 | 378 FOR_EACH_INSN_USE (use, call_insn) |
| 379 if (rtx_equal_p (addr, DF_REF_REG (use))) | |
| 0 | 380 break; |
| 381 | |
| 111 | 382 for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
| 0 | 383 if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
| 384 break; | |
| 385 | |
| 386 set = single_set (DF_REF_INSN (defs->ref)); | |
| 387 off += INTVAL (XEXP (SET_SRC (set), 1)); | |
| 388 } | |
| 111 | 389 for (byte = off; byte < off + MEM_SIZE (mem); byte++) |
| 0 | 390 { |
|
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391 if (!bitmap_set_bit (sp_bytes, byte - min_sp_off)) |
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392 gcc_unreachable (); |
| 0 | 393 } |
| 394 } | |
| 395 | |
| 396 /* Walk backwards, looking for argument stores. The search stops | |
| 397 when seeing another call, sp adjustment or memory store other than | |
| 398 argument store. */ | |
| 399 ret = false; | |
| 400 for (insn = PREV_INSN (call_insn); insn; insn = prev_insn) | |
| 401 { | |
| 402 rtx set, mem, addr; | |
|
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403 HOST_WIDE_INT off; |
| 0 | 404 |
| 405 if (insn == BB_HEAD (BLOCK_FOR_INSN (call_insn))) | |
| 111 | 406 prev_insn = NULL; |
| 0 | 407 else |
| 408 prev_insn = PREV_INSN (insn); | |
| 409 | |
| 410 if (CALL_P (insn)) | |
| 411 break; | |
| 412 | |
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413 if (!NONDEBUG_INSN_P (insn)) |
| 0 | 414 continue; |
| 415 | |
| 416 set = single_set (insn); | |
| 417 if (!set || SET_DEST (set) == stack_pointer_rtx) | |
| 418 break; | |
| 419 | |
| 420 if (!MEM_P (SET_DEST (set))) | |
| 421 continue; | |
| 422 | |
| 423 mem = SET_DEST (set); | |
| 424 addr = XEXP (mem, 0); | |
| 425 off = 0; | |
| 426 if (GET_CODE (addr) == PLUS | |
| 427 && REG_P (XEXP (addr, 0)) | |
| 428 && CONST_INT_P (XEXP (addr, 1))) | |
| 429 { | |
| 430 off = INTVAL (XEXP (addr, 1)); | |
| 431 addr = XEXP (addr, 0); | |
| 432 } | |
| 433 if (addr != stack_pointer_rtx) | |
| 434 { | |
| 435 if (!REG_P (addr)) | |
| 436 break; | |
| 437 if (!fast) | |
| 438 { | |
| 111 | 439 df_ref use; |
| 0 | 440 struct df_link *defs; |
| 441 rtx set; | |
| 442 | |
| 111 | 443 FOR_EACH_INSN_USE (use, insn) |
| 444 if (rtx_equal_p (addr, DF_REF_REG (use))) | |
| 0 | 445 break; |
| 446 | |
| 111 | 447 if (use == NULL) |
| 0 | 448 break; |
| 449 | |
| 111 | 450 for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) |
| 0 | 451 if (! DF_REF_IS_ARTIFICIAL (defs->ref)) |
| 452 break; | |
| 453 | |
| 454 if (defs == NULL) | |
| 455 break; | |
| 456 | |
| 457 set = single_set (DF_REF_INSN (defs->ref)); | |
| 458 if (!set) | |
| 459 break; | |
| 460 | |
| 461 if (GET_CODE (SET_SRC (set)) != PLUS | |
| 462 || XEXP (SET_SRC (set), 0) != stack_pointer_rtx | |
| 463 || !CONST_INT_P (XEXP (SET_SRC (set), 1))) | |
| 464 break; | |
| 465 | |
| 466 off += INTVAL (XEXP (SET_SRC (set), 1)); | |
| 467 } | |
| 468 else | |
| 469 break; | |
| 470 } | |
| 471 | |
| 111 | 472 if (!MEM_SIZE_KNOWN_P (mem) |
| 473 || !check_argument_store (MEM_SIZE (mem), off, min_sp_off, | |
|
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474 max_sp_off, sp_bytes)) |
| 0 | 475 break; |
| 476 | |
| 477 if (!deletable_insn_p (insn, fast, NULL)) | |
| 478 break; | |
| 479 | |
| 480 if (do_mark) | |
| 481 mark_insn (insn, fast); | |
| 482 else | |
| 483 bitmap_set_bit (arg_stores, INSN_UID (insn)); | |
| 484 | |
| 485 if (bitmap_empty_p (sp_bytes)) | |
| 486 { | |
| 487 ret = true; | |
| 488 break; | |
| 489 } | |
| 490 } | |
| 491 | |
| 492 BITMAP_FREE (sp_bytes); | |
| 493 if (!ret && arg_stores) | |
| 494 bitmap_clear (arg_stores); | |
| 495 | |
| 496 return ret; | |
| 497 } | |
| 498 | |
| 499 | |
|
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500 /* Remove all REG_EQUAL and REG_EQUIV notes referring to the registers INSN |
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501 writes to. */ |
| 0 | 502 |
| 503 static void | |
| 111 | 504 remove_reg_equal_equiv_notes_for_defs (rtx_insn *insn) |
| 0 | 505 { |
| 111 | 506 df_ref def; |
|
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507 |
| 111 | 508 FOR_EACH_INSN_DEF (def, insn) |
| 509 remove_reg_equal_equiv_notes_for_regno (DF_REF_REGNO (def)); | |
| 0 | 510 } |
| 511 | |
| 111 | 512 /* Scan all BBs for debug insns and reset those that reference values |
| 513 defined in unmarked insns. */ | |
| 514 | |
| 515 static void | |
| 516 reset_unmarked_insns_debug_uses (void) | |
| 517 { | |
| 518 basic_block bb; | |
| 519 rtx_insn *insn, *next; | |
| 520 | |
| 521 FOR_EACH_BB_REVERSE_FN (bb, cfun) | |
| 522 FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) | |
| 523 if (DEBUG_INSN_P (insn)) | |
| 524 { | |
| 525 df_ref use; | |
| 526 | |
| 527 FOR_EACH_INSN_USE (use, insn) | |
| 528 { | |
| 529 struct df_link *defs; | |
| 530 for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
| 531 { | |
| 532 rtx_insn *ref_insn; | |
| 533 if (DF_REF_IS_ARTIFICIAL (defs->ref)) | |
| 534 continue; | |
| 535 ref_insn = DF_REF_INSN (defs->ref); | |
| 536 if (!marked_insn_p (ref_insn)) | |
| 537 break; | |
| 538 } | |
| 539 if (!defs) | |
| 540 continue; | |
| 541 /* ??? FIXME could we propagate the values assigned to | |
| 542 each of the DEFs? */ | |
| 543 INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC (); | |
| 544 df_insn_rescan_debug_internal (insn); | |
| 545 break; | |
| 546 } | |
| 547 } | |
| 548 } | |
| 0 | 549 |
| 550 /* Delete every instruction that hasn't been marked. */ | |
| 551 | |
| 552 static void | |
| 553 delete_unmarked_insns (void) | |
| 554 { | |
| 555 basic_block bb; | |
| 111 | 556 rtx_insn *insn, *next; |
| 0 | 557 bool must_clean = false; |
| 558 | |
| 111 | 559 FOR_EACH_BB_REVERSE_FN (bb, cfun) |
| 0 | 560 FOR_BB_INSNS_REVERSE_SAFE (bb, insn, next) |
| 111 | 561 if (NONDEBUG_INSN_P (insn)) |
| 0 | 562 { |
| 563 /* Always delete no-op moves. */ | |
| 564 if (noop_move_p (insn)) | |
| 565 ; | |
| 566 | |
| 567 /* Otherwise rely only on the DCE algorithm. */ | |
| 568 else if (marked_insn_p (insn)) | |
| 569 continue; | |
| 570 | |
| 571 /* Beware that reaching a dbg counter limit here can result | |
| 572 in miscompiled file. This occurs when a group of insns | |
| 573 must be deleted together, typically because the kept insn | |
| 574 depends on the output from the deleted insn. Deleting | |
| 575 this insns in reverse order (both at the bb level and | |
| 576 when looking at the blocks) minimizes this, but does not | |
| 577 eliminate it, since it is possible for the using insn to | |
| 578 be top of a block and the producer to be at the bottom of | |
| 579 the block. However, in most cases this will only result | |
| 580 in an uninitialized use of an insn that is dead anyway. | |
| 581 | |
| 582 However, there is one rare case that will cause a | |
| 583 miscompile: deletion of non-looping pure and constant | |
| 584 calls on a machine where ACCUMULATE_OUTGOING_ARGS is true. | |
| 585 In this case it is possible to remove the call, but leave | |
| 586 the argument pushes to the stack. Because of the changes | |
| 587 to the stack pointer, this will almost always lead to a | |
| 588 miscompile. */ | |
| 589 if (!dbg_cnt (dce)) | |
| 590 continue; | |
| 591 | |
| 111 | 592 if (crtl->shrink_wrapped_separate |
| 593 && find_reg_note (insn, REG_CFA_RESTORE, NULL)) | |
| 594 { | |
| 595 if (dump_file) | |
| 596 fprintf (dump_file, "DCE: NOT deleting insn %d, it's a " | |
| 597 "callee-save restore\n", INSN_UID (insn)); | |
| 598 continue; | |
| 599 } | |
| 600 | |
| 0 | 601 if (dump_file) |
| 602 fprintf (dump_file, "DCE: Deleting insn %d\n", INSN_UID (insn)); | |
| 603 | |
|
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604 /* Before we delete the insn we have to remove the REG_EQUAL notes |
| 0 | 605 for the destination regs in order to avoid dangling notes. */ |
|
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606 remove_reg_equal_equiv_notes_for_defs (insn); |
| 0 | 607 |
| 608 /* If a pure or const call is deleted, this may make the cfg | |
| 609 have unreachable blocks. We rememeber this and call | |
| 610 delete_unreachable_blocks at the end. */ | |
| 611 if (CALL_P (insn)) | |
| 612 must_clean = true; | |
| 613 | |
| 614 /* Now delete the insn. */ | |
| 615 delete_insn_and_edges (insn); | |
| 616 } | |
| 617 | |
| 618 /* Deleted a pure or const call. */ | |
| 619 if (must_clean) | |
| 620 delete_unreachable_blocks (); | |
| 621 } | |
| 622 | |
| 623 | |
| 624 /* Go through the instructions and mark those whose necessity is not | |
| 625 dependent on inter-instruction information. Make sure all other | |
| 626 instructions are not marked. */ | |
| 627 | |
| 628 static void | |
| 629 prescan_insns_for_dce (bool fast) | |
| 630 { | |
| 631 basic_block bb; | |
| 111 | 632 rtx_insn *insn, *prev; |
| 0 | 633 bitmap arg_stores = NULL; |
| 634 | |
| 635 if (dump_file) | |
| 636 fprintf (dump_file, "Finding needed instructions:\n"); | |
| 637 | |
| 638 if (!df_in_progress && ACCUMULATE_OUTGOING_ARGS) | |
| 639 arg_stores = BITMAP_ALLOC (NULL); | |
| 640 | |
| 111 | 641 FOR_EACH_BB_FN (bb, cfun) |
| 0 | 642 { |
| 643 FOR_BB_INSNS_REVERSE_SAFE (bb, insn, prev) | |
| 111 | 644 if (NONDEBUG_INSN_P (insn)) |
| 0 | 645 { |
| 646 /* Don't mark argument stores now. They will be marked | |
| 647 if needed when the associated CALL is marked. */ | |
| 648 if (arg_stores && bitmap_bit_p (arg_stores, INSN_UID (insn))) | |
| 649 continue; | |
| 650 if (deletable_insn_p (insn, fast, arg_stores)) | |
| 651 mark_nonreg_stores (PATTERN (insn), insn, fast); | |
| 652 else | |
| 653 mark_insn (insn, fast); | |
| 654 } | |
| 655 /* find_call_stack_args only looks at argument stores in the | |
| 656 same bb. */ | |
| 657 if (arg_stores) | |
| 658 bitmap_clear (arg_stores); | |
| 659 } | |
| 660 | |
| 661 if (arg_stores) | |
| 662 BITMAP_FREE (arg_stores); | |
| 663 | |
| 664 if (dump_file) | |
| 665 fprintf (dump_file, "Finished finding needed instructions:\n"); | |
| 666 } | |
| 667 | |
| 668 | |
| 669 /* UD-based DSE routines. */ | |
| 670 | |
| 671 /* Mark instructions that define artificially-used registers, such as | |
| 672 the frame pointer and the stack pointer. */ | |
| 673 | |
| 674 static void | |
| 675 mark_artificial_uses (void) | |
| 676 { | |
| 677 basic_block bb; | |
| 678 struct df_link *defs; | |
| 111 | 679 df_ref use; |
| 0 | 680 |
| 111 | 681 FOR_ALL_BB_FN (bb, cfun) |
| 682 FOR_EACH_ARTIFICIAL_USE (use, bb->index) | |
| 683 for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
| 684 if (!DF_REF_IS_ARTIFICIAL (defs->ref)) | |
| 685 mark_insn (DF_REF_INSN (defs->ref), false); | |
| 0 | 686 } |
| 687 | |
| 688 | |
| 689 /* Mark every instruction that defines a register value that INSN uses. */ | |
| 690 | |
| 691 static void | |
| 111 | 692 mark_reg_dependencies (rtx_insn *insn) |
| 0 | 693 { |
| 694 struct df_link *defs; | |
| 111 | 695 df_ref use; |
| 0 | 696 |
|
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697 if (DEBUG_INSN_P (insn)) |
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698 return; |
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699 |
| 111 | 700 FOR_EACH_INSN_USE (use, insn) |
| 0 | 701 { |
| 702 if (dump_file) | |
| 703 { | |
| 704 fprintf (dump_file, "Processing use of "); | |
| 705 print_simple_rtl (dump_file, DF_REF_REG (use)); | |
| 706 fprintf (dump_file, " in insn %d:\n", INSN_UID (insn)); | |
| 707 } | |
| 708 for (defs = DF_REF_CHAIN (use); defs; defs = defs->next) | |
| 709 if (! DF_REF_IS_ARTIFICIAL (defs->ref)) | |
| 710 mark_insn (DF_REF_INSN (defs->ref), false); | |
| 711 } | |
| 712 } | |
| 713 | |
| 714 | |
| 715 /* Initialize global variables for a new DCE pass. */ | |
| 716 | |
| 717 static void | |
| 718 init_dce (bool fast) | |
| 719 { | |
| 720 if (!df_in_progress) | |
| 721 { | |
| 722 if (!fast) | |
| 111 | 723 { |
| 724 df_set_flags (DF_RD_PRUNE_DEAD_DEFS); | |
| 725 df_chain_add_problem (DF_UD_CHAIN); | |
| 726 } | |
| 0 | 727 df_analyze (); |
| 728 } | |
| 729 | |
| 730 if (dump_file) | |
| 731 df_dump (dump_file); | |
| 732 | |
| 733 if (fast) | |
| 734 { | |
| 735 bitmap_obstack_initialize (&dce_blocks_bitmap_obstack); | |
| 736 bitmap_obstack_initialize (&dce_tmp_bitmap_obstack); | |
| 111 | 737 can_alter_cfg = false; |
| 0 | 738 } |
| 111 | 739 else |
| 740 can_alter_cfg = true; | |
| 0 | 741 |
| 742 marked = sbitmap_alloc (get_max_uid () + 1); | |
| 111 | 743 bitmap_clear (marked); |
| 0 | 744 } |
| 745 | |
| 746 | |
| 747 /* Free the data allocated by init_dce. */ | |
| 748 | |
| 749 static void | |
| 750 fini_dce (bool fast) | |
| 751 { | |
| 752 sbitmap_free (marked); | |
| 753 | |
| 754 if (fast) | |
| 755 { | |
| 756 bitmap_obstack_release (&dce_blocks_bitmap_obstack); | |
| 757 bitmap_obstack_release (&dce_tmp_bitmap_obstack); | |
| 758 } | |
| 759 } | |
| 760 | |
| 761 | |
| 762 /* UD-chain based DCE. */ | |
| 763 | |
| 764 static unsigned int | |
| 765 rest_of_handle_ud_dce (void) | |
| 766 { | |
| 111 | 767 rtx_insn *insn; |
| 0 | 768 |
| 769 init_dce (false); | |
| 770 | |
| 771 prescan_insns_for_dce (false); | |
| 772 mark_artificial_uses (); | |
| 111 | 773 while (worklist.length () > 0) |
| 0 | 774 { |
| 111 | 775 insn = worklist.pop (); |
| 0 | 776 mark_reg_dependencies (insn); |
| 777 } | |
| 111 | 778 worklist.release (); |
| 779 | |
| 780 if (MAY_HAVE_DEBUG_INSNS) | |
| 781 reset_unmarked_insns_debug_uses (); | |
| 0 | 782 |
| 783 /* Before any insns are deleted, we must remove the chains since | |
| 784 they are not bidirectional. */ | |
| 785 df_remove_problem (df_chain); | |
| 786 delete_unmarked_insns (); | |
| 787 | |
| 788 fini_dce (false); | |
| 789 return 0; | |
| 790 } | |
| 791 | |
| 792 | |
| 111 | 793 namespace { |
| 794 | |
| 795 const pass_data pass_data_ud_rtl_dce = | |
| 0 | 796 { |
| 111 | 797 RTL_PASS, /* type */ |
| 798 "ud_dce", /* name */ | |
| 799 OPTGROUP_NONE, /* optinfo_flags */ | |
| 800 TV_DCE, /* tv_id */ | |
| 801 0, /* properties_required */ | |
| 802 0, /* properties_provided */ | |
| 803 0, /* properties_destroyed */ | |
| 804 0, /* todo_flags_start */ | |
| 805 TODO_df_finish, /* todo_flags_finish */ | |
| 806 }; | |
| 0 | 807 |
| 111 | 808 class pass_ud_rtl_dce : public rtl_opt_pass |
| 0 | 809 { |
| 111 | 810 public: |
| 811 pass_ud_rtl_dce (gcc::context *ctxt) | |
| 812 : rtl_opt_pass (pass_data_ud_rtl_dce, ctxt) | |
| 813 {} | |
| 814 | |
| 815 /* opt_pass methods: */ | |
| 816 virtual bool gate (function *) | |
| 817 { | |
| 818 return optimize > 1 && flag_dce && dbg_cnt (dce_ud); | |
| 819 } | |
| 820 | |
| 821 virtual unsigned int execute (function *) | |
| 822 { | |
| 823 return rest_of_handle_ud_dce (); | |
| 824 } | |
| 825 | |
| 826 }; // class pass_ud_rtl_dce | |
| 827 | |
| 828 } // anon namespace | |
| 829 | |
| 830 rtl_opt_pass * | |
| 831 make_pass_ud_rtl_dce (gcc::context *ctxt) | |
| 832 { | |
| 833 return new pass_ud_rtl_dce (ctxt); | |
| 834 } | |
| 0 | 835 |
| 836 | |
| 837 /* ------------------------------------------------------------------------- | |
| 838 Fast DCE functions | |
| 839 ------------------------------------------------------------------------- */ | |
| 840 | |
| 841 /* Process basic block BB. Return true if the live_in set has | |
| 842 changed. REDO_OUT is true if the info at the bottom of the block | |
| 843 needs to be recalculated before starting. AU is the proper set of | |
| 111 | 844 artificial uses. Track global substitution of uses of dead pseudos |
| 845 in debug insns using GLOBAL_DEBUG. */ | |
| 0 | 846 |
| 847 static bool | |
| 111 | 848 word_dce_process_block (basic_block bb, bool redo_out, |
| 849 struct dead_debug_global *global_debug) | |
| 0 | 850 { |
| 851 bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
| 111 | 852 rtx_insn *insn; |
| 0 | 853 bool block_changed; |
| 111 | 854 struct dead_debug_local debug; |
| 0 | 855 |
| 856 if (redo_out) | |
| 857 { | |
| 858 /* Need to redo the live_out set of this block if when one of | |
| 859 the succs of this block has had a change in it live in | |
| 860 set. */ | |
| 861 edge e; | |
| 862 edge_iterator ei; | |
|
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863 df_confluence_function_n con_fun_n = df_word_lr->problem->con_fun_n; |
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864 bitmap_clear (DF_WORD_LR_OUT (bb)); |
| 0 | 865 FOR_EACH_EDGE (e, ei, bb->succs) |
| 866 (*con_fun_n) (e); | |
| 867 } | |
| 868 | |
| 869 if (dump_file) | |
| 870 { | |
| 871 fprintf (dump_file, "processing block %d live out = ", bb->index); | |
|
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872 df_print_word_regset (dump_file, DF_WORD_LR_OUT (bb)); |
| 0 | 873 } |
| 874 | |
|
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875 bitmap_copy (local_live, DF_WORD_LR_OUT (bb)); |
| 111 | 876 dead_debug_local_init (&debug, NULL, global_debug); |
| 0 | 877 |
| 878 FOR_BB_INSNS_REVERSE (bb, insn) | |
| 111 | 879 if (DEBUG_INSN_P (insn)) |
| 880 { | |
| 881 df_ref use; | |
| 882 FOR_EACH_INSN_USE (use, insn) | |
| 883 if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER | |
| 884 && (GET_MODE_SIZE (GET_MODE (DF_REF_REAL_REG (use))) | |
| 885 == 2 * UNITS_PER_WORD) | |
| 886 && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use)) | |
| 887 && !bitmap_bit_p (local_live, 2 * DF_REF_REGNO (use) + 1)) | |
| 888 dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
| 889 } | |
| 890 else if (INSN_P (insn)) | |
| 0 | 891 { |
|
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892 bool any_changed; |
| 111 | 893 |
| 0 | 894 /* No matter if the instruction is needed or not, we remove |
| 895 any regno in the defs from the live set. */ | |
|
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896 any_changed = df_word_lr_simulate_defs (insn, local_live); |
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897 if (any_changed) |
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898 mark_insn (insn, true); |
| 0 | 899 |
| 900 /* On the other hand, we do not allow the dead uses to set | |
| 901 anything in local_live. */ | |
| 902 if (marked_insn_p (insn)) | |
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903 df_word_lr_simulate_uses (insn, local_live); |
| 0 | 904 |
| 111 | 905 /* Insert debug temps for dead REGs used in subsequent debug |
| 906 insns. We may have to emit a debug temp even if the insn | |
| 907 was marked, in case the debug use was after the point of | |
| 908 death. */ | |
| 909 if (debug.used && !bitmap_empty_p (debug.used)) | |
| 910 { | |
| 911 df_ref def; | |
| 912 | |
| 913 FOR_EACH_INSN_DEF (def, insn) | |
| 914 dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
| 915 marked_insn_p (insn) | |
| 916 && !control_flow_insn_p (insn) | |
| 917 ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
| 918 : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
| 919 } | |
| 920 | |
| 0 | 921 if (dump_file) |
| 922 { | |
|
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923 fprintf (dump_file, "finished processing insn %d live out = ", |
| 0 | 924 INSN_UID (insn)); |
|
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925 df_print_word_regset (dump_file, local_live); |
| 0 | 926 } |
| 927 } | |
|
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928 |
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929 block_changed = !bitmap_equal_p (local_live, DF_WORD_LR_IN (bb)); |
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930 if (block_changed) |
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931 bitmap_copy (DF_WORD_LR_IN (bb), local_live); |
| 0 | 932 |
| 111 | 933 dead_debug_local_finish (&debug, NULL); |
| 0 | 934 BITMAP_FREE (local_live); |
| 935 return block_changed; | |
| 936 } | |
| 937 | |
| 938 | |
| 939 /* Process basic block BB. Return true if the live_in set has | |
| 940 changed. REDO_OUT is true if the info at the bottom of the block | |
| 941 needs to be recalculated before starting. AU is the proper set of | |
| 111 | 942 artificial uses. Track global substitution of uses of dead pseudos |
| 943 in debug insns using GLOBAL_DEBUG. */ | |
| 0 | 944 |
| 945 static bool | |
| 111 | 946 dce_process_block (basic_block bb, bool redo_out, bitmap au, |
| 947 struct dead_debug_global *global_debug) | |
| 0 | 948 { |
| 949 bitmap local_live = BITMAP_ALLOC (&dce_tmp_bitmap_obstack); | |
| 111 | 950 rtx_insn *insn; |
| 0 | 951 bool block_changed; |
| 111 | 952 df_ref def; |
| 953 struct dead_debug_local debug; | |
| 0 | 954 |
| 955 if (redo_out) | |
| 956 { | |
| 957 /* Need to redo the live_out set of this block if when one of | |
| 958 the succs of this block has had a change in it live in | |
| 959 set. */ | |
| 960 edge e; | |
| 961 edge_iterator ei; | |
| 962 df_confluence_function_n con_fun_n = df_lr->problem->con_fun_n; | |
| 963 bitmap_clear (DF_LR_OUT (bb)); | |
| 964 FOR_EACH_EDGE (e, ei, bb->succs) | |
| 965 (*con_fun_n) (e); | |
| 966 } | |
| 967 | |
| 968 if (dump_file) | |
| 969 { | |
| 970 fprintf (dump_file, "processing block %d lr out = ", bb->index); | |
| 971 df_print_regset (dump_file, DF_LR_OUT (bb)); | |
| 972 } | |
| 973 | |
| 974 bitmap_copy (local_live, DF_LR_OUT (bb)); | |
| 975 | |
| 976 df_simulate_initialize_backwards (bb, local_live); | |
| 111 | 977 dead_debug_local_init (&debug, NULL, global_debug); |
| 0 | 978 |
| 979 FOR_BB_INSNS_REVERSE (bb, insn) | |
| 111 | 980 if (DEBUG_INSN_P (insn)) |
| 981 { | |
| 982 df_ref use; | |
| 983 FOR_EACH_INSN_USE (use, insn) | |
| 984 if (!bitmap_bit_p (local_live, DF_REF_REGNO (use)) | |
| 985 && !bitmap_bit_p (au, DF_REF_REGNO (use))) | |
| 986 dead_debug_add (&debug, use, DF_REF_REGNO (use)); | |
| 987 } | |
| 988 else if (INSN_P (insn)) | |
| 0 | 989 { |
|
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990 bool needed = marked_insn_p (insn); |
| 0 | 991 |
| 992 /* The insn is needed if there is someone who uses the output. */ | |
|
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993 if (!needed) |
| 111 | 994 FOR_EACH_INSN_DEF (def, insn) |
| 995 if (bitmap_bit_p (local_live, DF_REF_REGNO (def)) | |
| 996 || bitmap_bit_p (au, DF_REF_REGNO (def))) | |
|
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997 { |
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998 needed = true; |
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999 mark_insn (insn, true); |
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1000 break; |
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1001 } |
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1002 |
| 0 | 1003 /* No matter if the instruction is needed or not, we remove |
| 1004 any regno in the defs from the live set. */ | |
| 1005 df_simulate_defs (insn, local_live); | |
| 1006 | |
| 1007 /* On the other hand, we do not allow the dead uses to set | |
| 1008 anything in local_live. */ | |
|
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1009 if (needed) |
| 0 | 1010 df_simulate_uses (insn, local_live); |
| 111 | 1011 |
| 1012 /* Insert debug temps for dead REGs used in subsequent debug | |
| 1013 insns. We may have to emit a debug temp even if the insn | |
| 1014 was marked, in case the debug use was after the point of | |
| 1015 death. */ | |
| 1016 if (debug.used && !bitmap_empty_p (debug.used)) | |
| 1017 FOR_EACH_INSN_DEF (def, insn) | |
| 1018 dead_debug_insert_temp (&debug, DF_REF_REGNO (def), insn, | |
| 1019 needed && !control_flow_insn_p (insn) | |
| 1020 ? DEBUG_TEMP_AFTER_WITH_REG_FORCE | |
| 1021 : DEBUG_TEMP_BEFORE_WITH_VALUE); | |
| 0 | 1022 } |
|
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1023 |
| 111 | 1024 dead_debug_local_finish (&debug, NULL); |
| 0 | 1025 df_simulate_finalize_backwards (bb, local_live); |
| 1026 | |
| 1027 block_changed = !bitmap_equal_p (local_live, DF_LR_IN (bb)); | |
| 1028 if (block_changed) | |
| 1029 bitmap_copy (DF_LR_IN (bb), local_live); | |
| 1030 | |
| 1031 BITMAP_FREE (local_live); | |
| 1032 return block_changed; | |
| 1033 } | |
| 1034 | |
| 1035 | |
|
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1036 /* Perform fast DCE once initialization is done. If WORD_LEVEL is |
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1037 true, use the word level dce, otherwise do it at the pseudo |
| 0 | 1038 level. */ |
| 1039 | |
| 1040 static void | |
|
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1041 fast_dce (bool word_level) |
| 0 | 1042 { |
| 1043 int *postorder = df_get_postorder (DF_BACKWARD); | |
| 1044 int n_blocks = df_get_n_blocks (DF_BACKWARD); | |
| 1045 /* The set of blocks that have been seen on this iteration. */ | |
| 1046 bitmap processed = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
| 1047 /* The set of blocks that need to have the out vectors reset because | |
| 1048 the in of one of their successors has changed. */ | |
| 1049 bitmap redo_out = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
| 1050 bitmap all_blocks = BITMAP_ALLOC (&dce_blocks_bitmap_obstack); | |
| 1051 bool global_changed = true; | |
| 1052 | |
| 1053 /* These regs are considered always live so if they end up dying | |
| 1054 because of some def, we need to bring the back again. Calling | |
| 1055 df_simulate_fixup_sets has the disadvantage of calling | |
| 1056 bb_has_eh_pred once per insn, so we cache the information | |
| 1057 here. */ | |
|
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1058 bitmap au = &df->regular_block_artificial_uses; |
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1059 bitmap au_eh = &df->eh_block_artificial_uses; |
| 0 | 1060 int i; |
| 111 | 1061 struct dead_debug_global global_debug; |
| 0 | 1062 |
| 1063 prescan_insns_for_dce (true); | |
| 1064 | |
| 1065 for (i = 0; i < n_blocks; i++) | |
| 1066 bitmap_set_bit (all_blocks, postorder[i]); | |
| 1067 | |
| 111 | 1068 dead_debug_global_init (&global_debug, NULL); |
| 1069 | |
| 0 | 1070 while (global_changed) |
| 1071 { | |
| 1072 global_changed = false; | |
| 1073 | |
| 1074 for (i = 0; i < n_blocks; i++) | |
| 1075 { | |
| 1076 int index = postorder[i]; | |
| 111 | 1077 basic_block bb = BASIC_BLOCK_FOR_FN (cfun, index); |
| 0 | 1078 bool local_changed; |
| 1079 | |
| 1080 if (index < NUM_FIXED_BLOCKS) | |
| 1081 { | |
| 1082 bitmap_set_bit (processed, index); | |
| 1083 continue; | |
| 1084 } | |
| 1085 | |
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1086 if (word_level) |
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1087 local_changed |
| 111 | 1088 = word_dce_process_block (bb, bitmap_bit_p (redo_out, index), |
| 1089 &global_debug); | |
| 0 | 1090 else |
|
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1091 local_changed |
| 0 | 1092 = dce_process_block (bb, bitmap_bit_p (redo_out, index), |
| 111 | 1093 bb_has_eh_pred (bb) ? au_eh : au, |
| 1094 &global_debug); | |
| 0 | 1095 bitmap_set_bit (processed, index); |
|
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1096 |
| 0 | 1097 if (local_changed) |
| 1098 { | |
| 1099 edge e; | |
| 1100 edge_iterator ei; | |
| 1101 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 1102 if (bitmap_bit_p (processed, e->src->index)) | |
| 1103 /* Be tricky about when we need to iterate the | |
| 1104 analysis. We only have redo the analysis if the | |
| 1105 bitmaps change at the top of a block that is the | |
| 1106 entry to a loop. */ | |
| 1107 global_changed = true; | |
| 1108 else | |
| 1109 bitmap_set_bit (redo_out, e->src->index); | |
| 1110 } | |
| 1111 } | |
|
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1112 |
| 0 | 1113 if (global_changed) |
| 1114 { | |
| 1115 /* Turn off the RUN_DCE flag to prevent recursive calls to | |
| 1116 dce. */ | |
| 1117 int old_flag = df_clear_flags (DF_LR_RUN_DCE); | |
| 1118 | |
| 1119 /* So something was deleted that requires a redo. Do it on | |
| 1120 the cheap. */ | |
| 1121 delete_unmarked_insns (); | |
| 111 | 1122 bitmap_clear (marked); |
| 0 | 1123 bitmap_clear (processed); |
| 1124 bitmap_clear (redo_out); | |
|
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1125 |
| 0 | 1126 /* We do not need to rescan any instructions. We only need |
| 1127 to redo the dataflow equations for the blocks that had a | |
| 1128 change at the top of the block. Then we need to redo the | |
|
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1129 iteration. */ |
|
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1130 if (word_level) |
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1131 df_analyze_problem (df_word_lr, all_blocks, postorder, n_blocks); |
| 0 | 1132 else |
| 1133 df_analyze_problem (df_lr, all_blocks, postorder, n_blocks); | |
| 1134 | |
| 1135 if (old_flag & DF_LR_RUN_DCE) | |
| 1136 df_set_flags (DF_LR_RUN_DCE); | |
| 1137 | |
| 1138 prescan_insns_for_dce (true); | |
| 1139 } | |
| 1140 } | |
| 1141 | |
| 111 | 1142 dead_debug_global_finish (&global_debug, NULL); |
| 1143 | |
| 0 | 1144 delete_unmarked_insns (); |
| 1145 | |
| 1146 BITMAP_FREE (processed); | |
| 1147 BITMAP_FREE (redo_out); | |
| 1148 BITMAP_FREE (all_blocks); | |
| 1149 } | |
| 1150 | |
| 1151 | |
| 1152 /* Fast register level DCE. */ | |
| 1153 | |
| 1154 static unsigned int | |
| 1155 rest_of_handle_fast_dce (void) | |
| 1156 { | |
| 1157 init_dce (true); | |
| 1158 fast_dce (false); | |
| 1159 fini_dce (true); | |
| 1160 return 0; | |
| 1161 } | |
| 1162 | |
| 1163 | |
| 1164 /* Fast byte level DCE. */ | |
| 1165 | |
|
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1166 void |
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1167 run_word_dce (void) |
| 0 | 1168 { |
|
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1169 int old_flags; |
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1170 |
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1171 if (!flag_dce) |
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1172 return; |
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1173 |
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1174 timevar_push (TV_DCE); |
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1175 old_flags = df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
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1176 df_word_lr_add_problem (); |
| 0 | 1177 init_dce (true); |
| 1178 fast_dce (true); | |
| 1179 fini_dce (true); | |
|
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1180 df_set_flags (old_flags); |
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1181 timevar_pop (TV_DCE); |
| 0 | 1182 } |
| 1183 | |
| 1184 | |
| 1185 /* This is an internal call that is used by the df live register | |
| 1186 problem to run fast dce as a side effect of creating the live | |
| 1187 information. The stack is organized so that the lr problem is run, | |
| 1188 this pass is run, which updates the live info and the df scanning | |
| 1189 info, and then returns to allow the rest of the problems to be run. | |
| 1190 | |
| 1191 This can be called by elsewhere but it will not update the bit | |
| 1192 vectors for any other problems than LR. */ | |
| 1193 | |
| 1194 void | |
| 1195 run_fast_df_dce (void) | |
| 1196 { | |
| 1197 if (flag_dce) | |
| 1198 { | |
| 1199 /* If dce is able to delete something, it has to happen | |
| 1200 immediately. Otherwise there will be problems handling the | |
| 1201 eq_notes. */ | |
|
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1202 int old_flags = |
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1203 df_clear_flags (DF_DEFER_INSN_RESCAN + DF_NO_INSN_RESCAN); |
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1204 |
| 0 | 1205 df_in_progress = true; |
| 1206 rest_of_handle_fast_dce (); | |
| 1207 df_in_progress = false; | |
| 1208 | |
| 1209 df_set_flags (old_flags); | |
| 1210 } | |
| 1211 } | |
| 1212 | |
| 1213 | |
| 1214 /* Run a fast DCE pass. */ | |
| 1215 | |
| 1216 void | |
| 1217 run_fast_dce (void) | |
| 1218 { | |
| 1219 if (flag_dce) | |
| 1220 rest_of_handle_fast_dce (); | |
| 1221 } | |
| 1222 | |
| 1223 | |
| 111 | 1224 namespace { |
| 1225 | |
| 1226 const pass_data pass_data_fast_rtl_dce = | |
| 0 | 1227 { |
| 111 | 1228 RTL_PASS, /* type */ |
| 1229 "rtl_dce", /* name */ | |
| 1230 OPTGROUP_NONE, /* optinfo_flags */ | |
| 1231 TV_DCE, /* tv_id */ | |
| 1232 0, /* properties_required */ | |
| 1233 0, /* properties_provided */ | |
| 1234 0, /* properties_destroyed */ | |
| 1235 0, /* todo_flags_start */ | |
| 1236 TODO_df_finish, /* todo_flags_finish */ | |
| 1237 }; | |
| 0 | 1238 |
| 111 | 1239 class pass_fast_rtl_dce : public rtl_opt_pass |
| 0 | 1240 { |
| 111 | 1241 public: |
| 1242 pass_fast_rtl_dce (gcc::context *ctxt) | |
| 1243 : rtl_opt_pass (pass_data_fast_rtl_dce, ctxt) | |
| 1244 {} | |
| 1245 | |
| 1246 /* opt_pass methods: */ | |
| 1247 virtual bool gate (function *) | |
| 1248 { | |
| 1249 return optimize > 0 && flag_dce && dbg_cnt (dce_fast); | |
| 1250 } | |
| 1251 | |
| 1252 virtual unsigned int execute (function *) | |
| 1253 { | |
| 1254 return rest_of_handle_fast_dce (); | |
| 1255 } | |
| 1256 | |
| 1257 }; // class pass_fast_rtl_dce | |
| 1258 | |
| 1259 } // anon namespace | |
| 1260 | |
| 1261 rtl_opt_pass * | |
| 1262 make_pass_fast_rtl_dce (gcc::context *ctxt) | |
| 1263 { | |
| 1264 return new pass_fast_rtl_dce (ctxt); | |
| 1265 } |