Mercurial > hg > CbC > CbC_gcc
annotate gcc/cfgcleanup.c @ 59:5b5b9ea5b220
fix
| author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Mon, 15 Feb 2010 17:22:24 +0900 |
| parents | 77e2b8dfacca |
| children | b7f97abdc517 |
| rev | line source |
|---|---|
| 0 | 1 /* Control flow optimization code for GNU compiler. |
| 2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, | |
| 3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 | |
| 4 Free Software Foundation, Inc. | |
| 5 | |
| 6 This file is part of GCC. | |
| 7 | |
| 8 GCC is free software; you can redistribute it and/or modify it under | |
| 9 the terms of the GNU General Public License as published by the Free | |
| 10 Software Foundation; either version 3, or (at your option) any later | |
| 11 version. | |
| 12 | |
| 13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
| 14 WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 16 for more details. | |
| 17 | |
| 18 You should have received a copy of the GNU General Public License | |
| 19 along with GCC; see the file COPYING3. If not see | |
| 20 <http://www.gnu.org/licenses/>. */ | |
| 21 | |
| 22 /* This file contains optimizer of the control flow. The main entry point is | |
| 23 cleanup_cfg. Following optimizations are performed: | |
| 24 | |
| 25 - Unreachable blocks removal | |
| 26 - Edge forwarding (edge to the forwarder block is forwarded to its | |
| 27 successor. Simplification of the branch instruction is performed by | |
| 28 underlying infrastructure so branch can be converted to simplejump or | |
| 29 eliminated). | |
| 30 - Cross jumping (tail merging) | |
| 31 - Conditional jump-around-simplejump simplification | |
| 32 - Basic block merging. */ | |
| 33 | |
| 34 #include "config.h" | |
| 35 #include "system.h" | |
| 36 #include "coretypes.h" | |
| 37 #include "tm.h" | |
| 38 #include "rtl.h" | |
| 39 #include "hard-reg-set.h" | |
| 40 #include "regs.h" | |
| 41 #include "timevar.h" | |
| 42 #include "output.h" | |
| 43 #include "insn-config.h" | |
| 44 #include "flags.h" | |
| 45 #include "recog.h" | |
| 46 #include "toplev.h" | |
| 47 #include "cselib.h" | |
| 48 #include "params.h" | |
| 49 #include "tm_p.h" | |
| 50 #include "target.h" | |
| 51 #include "cfglayout.h" | |
| 52 #include "emit-rtl.h" | |
| 53 #include "tree-pass.h" | |
| 54 #include "cfgloop.h" | |
| 55 #include "expr.h" | |
| 56 #include "df.h" | |
| 57 #include "dce.h" | |
| 58 #include "dbgcnt.h" | |
| 59 | |
| 60 #define FORWARDER_BLOCK_P(BB) ((BB)->flags & BB_FORWARDER_BLOCK) | |
| 61 | |
| 62 /* Set to true when we are running first pass of try_optimize_cfg loop. */ | |
| 63 static bool first_pass; | |
| 64 | |
| 65 /* Set to true if crossjumps occured in the latest run of try_optimize_cfg. */ | |
| 66 static bool crossjumps_occured; | |
| 67 | |
| 68 static bool try_crossjump_to_edge (int, edge, edge); | |
| 69 static bool try_crossjump_bb (int, basic_block); | |
| 70 static bool outgoing_edges_match (int, basic_block, basic_block); | |
| 71 static int flow_find_cross_jump (int, basic_block, basic_block, rtx *, rtx *); | |
| 72 static bool old_insns_match_p (int, rtx, rtx); | |
| 73 | |
| 74 static void merge_blocks_move_predecessor_nojumps (basic_block, basic_block); | |
| 75 static void merge_blocks_move_successor_nojumps (basic_block, basic_block); | |
| 76 static bool try_optimize_cfg (int); | |
| 77 static bool try_simplify_condjump (basic_block); | |
| 78 static bool try_forward_edges (int, basic_block); | |
| 79 static edge thread_jump (edge, basic_block); | |
| 80 static bool mark_effect (rtx, bitmap); | |
| 81 static void notice_new_block (basic_block); | |
| 82 static void update_forwarder_flag (basic_block); | |
| 83 static int mentions_nonequal_regs (rtx *, void *); | |
| 84 static void merge_memattrs (rtx, rtx); | |
| 85 | |
| 86 /* Set flags for newly created block. */ | |
| 87 | |
| 88 static void | |
| 89 notice_new_block (basic_block bb) | |
| 90 { | |
| 91 if (!bb) | |
| 92 return; | |
| 93 | |
| 94 if (forwarder_block_p (bb)) | |
| 95 bb->flags |= BB_FORWARDER_BLOCK; | |
| 96 } | |
| 97 | |
| 98 /* Recompute forwarder flag after block has been modified. */ | |
| 99 | |
| 100 static void | |
| 101 update_forwarder_flag (basic_block bb) | |
| 102 { | |
| 103 if (forwarder_block_p (bb)) | |
| 104 bb->flags |= BB_FORWARDER_BLOCK; | |
| 105 else | |
| 106 bb->flags &= ~BB_FORWARDER_BLOCK; | |
| 107 } | |
| 108 | |
| 109 /* Simplify a conditional jump around an unconditional jump. | |
| 110 Return true if something changed. */ | |
| 111 | |
| 112 static bool | |
| 113 try_simplify_condjump (basic_block cbranch_block) | |
| 114 { | |
| 115 basic_block jump_block, jump_dest_block, cbranch_dest_block; | |
| 116 edge cbranch_jump_edge, cbranch_fallthru_edge; | |
| 117 rtx cbranch_insn; | |
| 118 | |
| 119 /* Verify that there are exactly two successors. */ | |
| 120 if (EDGE_COUNT (cbranch_block->succs) != 2) | |
| 121 return false; | |
| 122 | |
| 123 /* Verify that we've got a normal conditional branch at the end | |
| 124 of the block. */ | |
| 125 cbranch_insn = BB_END (cbranch_block); | |
| 126 if (!any_condjump_p (cbranch_insn)) | |
| 127 return false; | |
| 128 | |
| 129 cbranch_fallthru_edge = FALLTHRU_EDGE (cbranch_block); | |
| 130 cbranch_jump_edge = BRANCH_EDGE (cbranch_block); | |
| 131 | |
| 132 /* The next block must not have multiple predecessors, must not | |
| 133 be the last block in the function, and must contain just the | |
| 134 unconditional jump. */ | |
| 135 jump_block = cbranch_fallthru_edge->dest; | |
| 136 if (!single_pred_p (jump_block) | |
| 137 || jump_block->next_bb == EXIT_BLOCK_PTR | |
| 138 || !FORWARDER_BLOCK_P (jump_block)) | |
| 139 return false; | |
| 140 jump_dest_block = single_succ (jump_block); | |
| 141 | |
| 142 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 143 mess up unconditional or indirect jumps that cross between hot | |
| 144 and cold sections. | |
| 145 | |
| 146 Basic block partitioning may result in some jumps that appear to | |
| 147 be optimizable (or blocks that appear to be mergeable), but which really | |
| 148 must be left untouched (they are required to make it safely across | |
| 149 partition boundaries). See the comments at the top of | |
| 150 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 151 | |
| 152 if (BB_PARTITION (jump_block) != BB_PARTITION (jump_dest_block) | |
| 153 || (cbranch_jump_edge->flags & EDGE_CROSSING)) | |
| 154 return false; | |
| 155 | |
| 156 /* The conditional branch must target the block after the | |
| 157 unconditional branch. */ | |
| 158 cbranch_dest_block = cbranch_jump_edge->dest; | |
| 159 | |
| 160 if (cbranch_dest_block == EXIT_BLOCK_PTR | |
| 161 || !can_fallthru (jump_block, cbranch_dest_block)) | |
| 162 return false; | |
| 163 | |
| 164 /* Invert the conditional branch. */ | |
| 165 if (!invert_jump (cbranch_insn, block_label (jump_dest_block), 0)) | |
| 166 return false; | |
| 167 | |
| 168 if (dump_file) | |
| 169 fprintf (dump_file, "Simplifying condjump %i around jump %i\n", | |
| 170 INSN_UID (cbranch_insn), INSN_UID (BB_END (jump_block))); | |
| 171 | |
| 172 /* Success. Update the CFG to match. Note that after this point | |
| 173 the edge variable names appear backwards; the redirection is done | |
| 174 this way to preserve edge profile data. */ | |
| 175 cbranch_jump_edge = redirect_edge_succ_nodup (cbranch_jump_edge, | |
| 176 cbranch_dest_block); | |
| 177 cbranch_fallthru_edge = redirect_edge_succ_nodup (cbranch_fallthru_edge, | |
| 178 jump_dest_block); | |
| 179 cbranch_jump_edge->flags |= EDGE_FALLTHRU; | |
| 180 cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU; | |
| 181 update_br_prob_note (cbranch_block); | |
| 182 | |
| 183 /* Delete the block with the unconditional jump, and clean up the mess. */ | |
| 184 delete_basic_block (jump_block); | |
| 185 tidy_fallthru_edge (cbranch_jump_edge); | |
| 186 update_forwarder_flag (cbranch_block); | |
| 187 | |
| 188 return true; | |
| 189 } | |
| 190 | |
| 191 /* Attempt to prove that operation is NOOP using CSElib or mark the effect | |
| 192 on register. Used by jump threading. */ | |
| 193 | |
| 194 static bool | |
| 195 mark_effect (rtx exp, regset nonequal) | |
| 196 { | |
| 197 int regno; | |
| 198 rtx dest; | |
| 199 switch (GET_CODE (exp)) | |
| 200 { | |
| 201 /* In case we do clobber the register, mark it as equal, as we know the | |
| 202 value is dead so it don't have to match. */ | |
| 203 case CLOBBER: | |
| 204 if (REG_P (XEXP (exp, 0))) | |
| 205 { | |
| 206 dest = XEXP (exp, 0); | |
| 207 regno = REGNO (dest); | |
| 208 CLEAR_REGNO_REG_SET (nonequal, regno); | |
| 209 if (regno < FIRST_PSEUDO_REGISTER) | |
| 210 { | |
| 211 int n = hard_regno_nregs[regno][GET_MODE (dest)]; | |
| 212 while (--n > 0) | |
| 213 CLEAR_REGNO_REG_SET (nonequal, regno + n); | |
| 214 } | |
| 215 } | |
| 216 return false; | |
| 217 | |
| 218 case SET: | |
| 219 if (rtx_equal_for_cselib_p (SET_DEST (exp), SET_SRC (exp))) | |
| 220 return false; | |
| 221 dest = SET_DEST (exp); | |
| 222 if (dest == pc_rtx) | |
| 223 return false; | |
| 224 if (!REG_P (dest)) | |
| 225 return true; | |
| 226 regno = REGNO (dest); | |
| 227 SET_REGNO_REG_SET (nonequal, regno); | |
| 228 if (regno < FIRST_PSEUDO_REGISTER) | |
| 229 { | |
| 230 int n = hard_regno_nregs[regno][GET_MODE (dest)]; | |
| 231 while (--n > 0) | |
| 232 SET_REGNO_REG_SET (nonequal, regno + n); | |
| 233 } | |
| 234 return false; | |
| 235 | |
| 236 default: | |
| 237 return false; | |
| 238 } | |
| 239 } | |
| 240 | |
| 241 /* Return nonzero if X is a register set in regset DATA. | |
| 242 Called via for_each_rtx. */ | |
| 243 static int | |
| 244 mentions_nonequal_regs (rtx *x, void *data) | |
| 245 { | |
| 246 regset nonequal = (regset) data; | |
| 247 if (REG_P (*x)) | |
| 248 { | |
| 249 int regno; | |
| 250 | |
| 251 regno = REGNO (*x); | |
| 252 if (REGNO_REG_SET_P (nonequal, regno)) | |
| 253 return 1; | |
| 254 if (regno < FIRST_PSEUDO_REGISTER) | |
| 255 { | |
| 256 int n = hard_regno_nregs[regno][GET_MODE (*x)]; | |
| 257 while (--n > 0) | |
| 258 if (REGNO_REG_SET_P (nonequal, regno + n)) | |
| 259 return 1; | |
| 260 } | |
| 261 } | |
| 262 return 0; | |
| 263 } | |
| 264 /* Attempt to prove that the basic block B will have no side effects and | |
| 265 always continues in the same edge if reached via E. Return the edge | |
| 266 if exist, NULL otherwise. */ | |
| 267 | |
| 268 static edge | |
| 269 thread_jump (edge e, basic_block b) | |
| 270 { | |
| 271 rtx set1, set2, cond1, cond2, insn; | |
| 272 enum rtx_code code1, code2, reversed_code2; | |
| 273 bool reverse1 = false; | |
| 274 unsigned i; | |
| 275 regset nonequal; | |
| 276 bool failed = false; | |
| 277 reg_set_iterator rsi; | |
| 278 | |
| 279 if (b->flags & BB_NONTHREADABLE_BLOCK) | |
| 280 return NULL; | |
| 281 | |
| 282 /* At the moment, we do handle only conditional jumps, but later we may | |
| 283 want to extend this code to tablejumps and others. */ | |
| 284 if (EDGE_COUNT (e->src->succs) != 2) | |
| 285 return NULL; | |
| 286 if (EDGE_COUNT (b->succs) != 2) | |
| 287 { | |
| 288 b->flags |= BB_NONTHREADABLE_BLOCK; | |
| 289 return NULL; | |
| 290 } | |
| 291 | |
| 292 /* Second branch must end with onlyjump, as we will eliminate the jump. */ | |
| 293 if (!any_condjump_p (BB_END (e->src))) | |
| 294 return NULL; | |
| 295 | |
| 296 if (!any_condjump_p (BB_END (b)) || !onlyjump_p (BB_END (b))) | |
| 297 { | |
| 298 b->flags |= BB_NONTHREADABLE_BLOCK; | |
| 299 return NULL; | |
| 300 } | |
| 301 | |
| 302 set1 = pc_set (BB_END (e->src)); | |
| 303 set2 = pc_set (BB_END (b)); | |
| 304 if (((e->flags & EDGE_FALLTHRU) != 0) | |
| 305 != (XEXP (SET_SRC (set1), 1) == pc_rtx)) | |
| 306 reverse1 = true; | |
| 307 | |
| 308 cond1 = XEXP (SET_SRC (set1), 0); | |
| 309 cond2 = XEXP (SET_SRC (set2), 0); | |
| 310 if (reverse1) | |
| 311 code1 = reversed_comparison_code (cond1, BB_END (e->src)); | |
| 312 else | |
| 313 code1 = GET_CODE (cond1); | |
| 314 | |
| 315 code2 = GET_CODE (cond2); | |
| 316 reversed_code2 = reversed_comparison_code (cond2, BB_END (b)); | |
| 317 | |
| 318 if (!comparison_dominates_p (code1, code2) | |
| 319 && !comparison_dominates_p (code1, reversed_code2)) | |
| 320 return NULL; | |
| 321 | |
| 322 /* Ensure that the comparison operators are equivalent. | |
| 323 ??? This is far too pessimistic. We should allow swapped operands, | |
| 324 different CCmodes, or for example comparisons for interval, that | |
| 325 dominate even when operands are not equivalent. */ | |
| 326 if (!rtx_equal_p (XEXP (cond1, 0), XEXP (cond2, 0)) | |
| 327 || !rtx_equal_p (XEXP (cond1, 1), XEXP (cond2, 1))) | |
| 328 return NULL; | |
| 329 | |
| 330 /* Short circuit cases where block B contains some side effects, as we can't | |
| 331 safely bypass it. */ | |
| 332 for (insn = NEXT_INSN (BB_HEAD (b)); insn != NEXT_INSN (BB_END (b)); | |
| 333 insn = NEXT_INSN (insn)) | |
| 334 if (INSN_P (insn) && side_effects_p (PATTERN (insn))) | |
| 335 { | |
| 336 b->flags |= BB_NONTHREADABLE_BLOCK; | |
| 337 return NULL; | |
| 338 } | |
| 339 | |
| 340 cselib_init (false); | |
| 341 | |
| 342 /* First process all values computed in the source basic block. */ | |
| 343 for (insn = NEXT_INSN (BB_HEAD (e->src)); | |
| 344 insn != NEXT_INSN (BB_END (e->src)); | |
| 345 insn = NEXT_INSN (insn)) | |
| 346 if (INSN_P (insn)) | |
| 347 cselib_process_insn (insn); | |
| 348 | |
| 349 nonequal = BITMAP_ALLOC (NULL); | |
| 350 CLEAR_REG_SET (nonequal); | |
| 351 | |
| 352 /* Now assume that we've continued by the edge E to B and continue | |
| 353 processing as if it were same basic block. | |
| 354 Our goal is to prove that whole block is an NOOP. */ | |
| 355 | |
| 356 for (insn = NEXT_INSN (BB_HEAD (b)); | |
| 357 insn != NEXT_INSN (BB_END (b)) && !failed; | |
| 358 insn = NEXT_INSN (insn)) | |
| 359 { | |
| 360 if (INSN_P (insn)) | |
| 361 { | |
| 362 rtx pat = PATTERN (insn); | |
| 363 | |
| 364 if (GET_CODE (pat) == PARALLEL) | |
| 365 { | |
| 366 for (i = 0; i < (unsigned)XVECLEN (pat, 0); i++) | |
| 367 failed |= mark_effect (XVECEXP (pat, 0, i), nonequal); | |
| 368 } | |
| 369 else | |
| 370 failed |= mark_effect (pat, nonequal); | |
| 371 } | |
| 372 | |
| 373 cselib_process_insn (insn); | |
| 374 } | |
| 375 | |
| 376 /* Later we should clear nonequal of dead registers. So far we don't | |
| 377 have life information in cfg_cleanup. */ | |
| 378 if (failed) | |
| 379 { | |
| 380 b->flags |= BB_NONTHREADABLE_BLOCK; | |
| 381 goto failed_exit; | |
| 382 } | |
| 383 | |
| 384 /* cond2 must not mention any register that is not equal to the | |
| 385 former block. */ | |
| 386 if (for_each_rtx (&cond2, mentions_nonequal_regs, nonequal)) | |
| 387 goto failed_exit; | |
| 388 | |
| 389 EXECUTE_IF_SET_IN_REG_SET (nonequal, 0, i, rsi) | |
| 390 goto failed_exit; | |
| 391 | |
| 392 BITMAP_FREE (nonequal); | |
| 393 cselib_finish (); | |
| 394 if ((comparison_dominates_p (code1, code2) != 0) | |
| 395 != (XEXP (SET_SRC (set2), 1) == pc_rtx)) | |
| 396 return BRANCH_EDGE (b); | |
| 397 else | |
| 398 return FALLTHRU_EDGE (b); | |
| 399 | |
| 400 failed_exit: | |
| 401 BITMAP_FREE (nonequal); | |
| 402 cselib_finish (); | |
| 403 return NULL; | |
| 404 } | |
| 405 | |
| 406 /* Attempt to forward edges leaving basic block B. | |
| 407 Return true if successful. */ | |
| 408 | |
| 409 static bool | |
| 410 try_forward_edges (int mode, basic_block b) | |
| 411 { | |
| 412 bool changed = false; | |
| 413 edge_iterator ei; | |
| 414 edge e, *threaded_edges = NULL; | |
| 415 | |
| 416 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 417 mess up unconditional or indirect jumps that cross between hot | |
| 418 and cold sections. | |
| 419 | |
| 420 Basic block partitioning may result in some jumps that appear to | |
| 421 be optimizable (or blocks that appear to be mergeable), but which really | |
| 422 must be left untouched (they are required to make it safely across | |
| 423 partition boundaries). See the comments at the top of | |
| 424 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 425 | |
| 426 if (find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)) | |
| 427 return false; | |
| 428 | |
| 429 for (ei = ei_start (b->succs); (e = ei_safe_edge (ei)); ) | |
| 430 { | |
| 431 basic_block target, first; | |
| 432 int counter, goto_locus; | |
| 433 bool threaded = false; | |
| 434 int nthreaded_edges = 0; | |
| 435 bool may_thread = first_pass | df_get_bb_dirty (b); | |
| 436 | |
| 437 /* Skip complex edges because we don't know how to update them. | |
| 438 | |
| 439 Still handle fallthru edges, as we can succeed to forward fallthru | |
| 440 edge to the same place as the branch edge of conditional branch | |
| 441 and turn conditional branch to an unconditional branch. */ | |
| 442 if (e->flags & EDGE_COMPLEX) | |
| 443 { | |
| 444 ei_next (&ei); | |
| 445 continue; | |
| 446 } | |
| 447 | |
| 448 target = first = e->dest; | |
| 449 counter = NUM_FIXED_BLOCKS; | |
| 450 goto_locus = e->goto_locus; | |
| 451 | |
| 452 /* If we are partitioning hot/cold basic_blocks, we don't want to mess | |
| 453 up jumps that cross between hot/cold sections. | |
| 454 | |
| 455 Basic block partitioning may result in some jumps that appear | |
| 456 to be optimizable (or blocks that appear to be mergeable), but which | |
| 457 really must be left untouched (they are required to make it safely | |
| 458 across partition boundaries). See the comments at the top of | |
| 459 bb-reorder.c:partition_hot_cold_basic_blocks for complete | |
| 460 details. */ | |
| 461 | |
| 462 if (first != EXIT_BLOCK_PTR | |
| 463 && find_reg_note (BB_END (first), REG_CROSSING_JUMP, NULL_RTX)) | |
| 464 return false; | |
| 465 | |
| 466 while (counter < n_basic_blocks) | |
| 467 { | |
| 468 basic_block new_target = NULL; | |
| 469 bool new_target_threaded = false; | |
| 470 may_thread |= df_get_bb_dirty (target); | |
| 471 | |
| 472 if (FORWARDER_BLOCK_P (target) | |
| 473 && !(single_succ_edge (target)->flags & EDGE_CROSSING) | |
| 474 && single_succ (target) != EXIT_BLOCK_PTR) | |
| 475 { | |
| 476 /* Bypass trivial infinite loops. */ | |
| 477 new_target = single_succ (target); | |
| 478 if (target == new_target) | |
| 479 counter = n_basic_blocks; | |
| 480 else if (!optimize) | |
| 481 { | |
| 482 /* When not optimizing, ensure that edges or forwarder | |
| 483 blocks with different locus are not optimized out. */ | |
| 484 int locus = single_succ_edge (target)->goto_locus; | |
| 485 | |
| 486 if (locus && goto_locus && !locator_eq (locus, goto_locus)) | |
| 487 counter = n_basic_blocks; | |
| 488 else if (locus) | |
| 489 goto_locus = locus; | |
| 490 | |
| 491 if (INSN_P (BB_END (target))) | |
| 492 { | |
| 493 locus = INSN_LOCATOR (BB_END (target)); | |
| 494 | |
| 495 if (locus && goto_locus | |
| 496 && !locator_eq (locus, goto_locus)) | |
| 497 counter = n_basic_blocks; | |
| 498 else if (locus) | |
| 499 goto_locus = locus; | |
| 500 } | |
| 501 } | |
| 502 } | |
| 503 | |
| 504 /* Allow to thread only over one edge at time to simplify updating | |
| 505 of probabilities. */ | |
| 506 else if ((mode & CLEANUP_THREADING) && may_thread) | |
| 507 { | |
| 508 edge t = thread_jump (e, target); | |
| 509 if (t) | |
| 510 { | |
| 511 if (!threaded_edges) | |
| 512 threaded_edges = XNEWVEC (edge, n_basic_blocks); | |
| 513 else | |
| 514 { | |
| 515 int i; | |
| 516 | |
| 517 /* Detect an infinite loop across blocks not | |
| 518 including the start block. */ | |
| 519 for (i = 0; i < nthreaded_edges; ++i) | |
| 520 if (threaded_edges[i] == t) | |
| 521 break; | |
| 522 if (i < nthreaded_edges) | |
| 523 { | |
| 524 counter = n_basic_blocks; | |
| 525 break; | |
| 526 } | |
| 527 } | |
| 528 | |
| 529 /* Detect an infinite loop across the start block. */ | |
| 530 if (t->dest == b) | |
| 531 break; | |
| 532 | |
| 533 gcc_assert (nthreaded_edges < n_basic_blocks - NUM_FIXED_BLOCKS); | |
| 534 threaded_edges[nthreaded_edges++] = t; | |
| 535 | |
| 536 new_target = t->dest; | |
| 537 new_target_threaded = true; | |
| 538 } | |
| 539 } | |
| 540 | |
| 541 if (!new_target) | |
| 542 break; | |
| 543 | |
| 544 counter++; | |
| 545 target = new_target; | |
| 546 threaded |= new_target_threaded; | |
| 547 } | |
| 548 | |
| 549 if (counter >= n_basic_blocks) | |
| 550 { | |
| 551 if (dump_file) | |
| 552 fprintf (dump_file, "Infinite loop in BB %i.\n", | |
| 553 target->index); | |
| 554 } | |
| 555 else if (target == first) | |
| 556 ; /* We didn't do anything. */ | |
| 557 else | |
| 558 { | |
| 559 /* Save the values now, as the edge may get removed. */ | |
| 560 gcov_type edge_count = e->count; | |
| 561 int edge_probability = e->probability; | |
| 562 int edge_frequency; | |
| 563 int n = 0; | |
| 564 | |
| 565 e->goto_locus = goto_locus; | |
| 566 | |
| 567 /* Don't force if target is exit block. */ | |
| 568 if (threaded && target != EXIT_BLOCK_PTR) | |
| 569 { | |
| 570 notice_new_block (redirect_edge_and_branch_force (e, target)); | |
| 571 if (dump_file) | |
| 572 fprintf (dump_file, "Conditionals threaded.\n"); | |
| 573 } | |
| 574 else if (!redirect_edge_and_branch (e, target)) | |
| 575 { | |
| 576 if (dump_file) | |
| 577 fprintf (dump_file, | |
| 578 "Forwarding edge %i->%i to %i failed.\n", | |
| 579 b->index, e->dest->index, target->index); | |
| 580 ei_next (&ei); | |
| 581 continue; | |
| 582 } | |
| 583 | |
| 584 /* We successfully forwarded the edge. Now update profile | |
| 585 data: for each edge we traversed in the chain, remove | |
| 586 the original edge's execution count. */ | |
| 587 edge_frequency = ((edge_probability * b->frequency | |
| 588 + REG_BR_PROB_BASE / 2) | |
| 589 / REG_BR_PROB_BASE); | |
| 590 | |
| 591 if (!FORWARDER_BLOCK_P (b) && forwarder_block_p (b)) | |
| 592 b->flags |= BB_FORWARDER_BLOCK; | |
| 593 | |
| 594 do | |
| 595 { | |
| 596 edge t; | |
| 597 | |
| 598 if (!single_succ_p (first)) | |
| 599 { | |
| 600 gcc_assert (n < nthreaded_edges); | |
| 601 t = threaded_edges [n++]; | |
| 602 gcc_assert (t->src == first); | |
| 603 update_bb_profile_for_threading (first, edge_frequency, | |
| 604 edge_count, t); | |
| 605 update_br_prob_note (first); | |
| 606 } | |
| 607 else | |
| 608 { | |
| 609 first->count -= edge_count; | |
| 610 if (first->count < 0) | |
| 611 first->count = 0; | |
| 612 first->frequency -= edge_frequency; | |
| 613 if (first->frequency < 0) | |
| 614 first->frequency = 0; | |
| 615 /* It is possible that as the result of | |
| 616 threading we've removed edge as it is | |
| 617 threaded to the fallthru edge. Avoid | |
| 618 getting out of sync. */ | |
| 619 if (n < nthreaded_edges | |
| 620 && first == threaded_edges [n]->src) | |
| 621 n++; | |
| 622 t = single_succ_edge (first); | |
| 623 } | |
| 624 | |
| 625 t->count -= edge_count; | |
| 626 if (t->count < 0) | |
| 627 t->count = 0; | |
| 628 first = t->dest; | |
| 629 } | |
| 630 while (first != target); | |
| 631 | |
| 632 changed = true; | |
| 633 continue; | |
| 634 } | |
| 635 ei_next (&ei); | |
| 636 } | |
| 637 | |
| 638 if (threaded_edges) | |
| 639 free (threaded_edges); | |
| 640 return changed; | |
| 641 } | |
| 642 | |
| 643 | |
| 644 /* Blocks A and B are to be merged into a single block. A has no incoming | |
| 645 fallthru edge, so it can be moved before B without adding or modifying | |
| 646 any jumps (aside from the jump from A to B). */ | |
| 647 | |
| 648 static void | |
| 649 merge_blocks_move_predecessor_nojumps (basic_block a, basic_block b) | |
| 650 { | |
| 651 rtx barrier; | |
| 652 | |
| 653 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 654 mess up unconditional or indirect jumps that cross between hot | |
| 655 and cold sections. | |
| 656 | |
| 657 Basic block partitioning may result in some jumps that appear to | |
| 658 be optimizable (or blocks that appear to be mergeable), but which really | |
| 659 must be left untouched (they are required to make it safely across | |
| 660 partition boundaries). See the comments at the top of | |
| 661 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 662 | |
| 663 if (BB_PARTITION (a) != BB_PARTITION (b)) | |
| 664 return; | |
| 665 | |
| 666 barrier = next_nonnote_insn (BB_END (a)); | |
| 667 gcc_assert (BARRIER_P (barrier)); | |
| 668 delete_insn (barrier); | |
| 669 | |
| 670 /* Scramble the insn chain. */ | |
| 671 if (BB_END (a) != PREV_INSN (BB_HEAD (b))) | |
| 672 reorder_insns_nobb (BB_HEAD (a), BB_END (a), PREV_INSN (BB_HEAD (b))); | |
| 673 df_set_bb_dirty (a); | |
| 674 | |
| 675 if (dump_file) | |
| 676 fprintf (dump_file, "Moved block %d before %d and merged.\n", | |
| 677 a->index, b->index); | |
| 678 | |
| 679 /* Swap the records for the two blocks around. */ | |
| 680 | |
| 681 unlink_block (a); | |
| 682 link_block (a, b->prev_bb); | |
| 683 | |
| 684 /* Now blocks A and B are contiguous. Merge them. */ | |
| 685 merge_blocks (a, b); | |
| 686 } | |
| 687 | |
| 688 /* Blocks A and B are to be merged into a single block. B has no outgoing | |
| 689 fallthru edge, so it can be moved after A without adding or modifying | |
| 690 any jumps (aside from the jump from A to B). */ | |
| 691 | |
| 692 static void | |
| 693 merge_blocks_move_successor_nojumps (basic_block a, basic_block b) | |
| 694 { | |
| 695 rtx barrier, real_b_end; | |
| 696 rtx label, table; | |
| 697 | |
| 698 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 699 mess up unconditional or indirect jumps that cross between hot | |
| 700 and cold sections. | |
| 701 | |
| 702 Basic block partitioning may result in some jumps that appear to | |
| 703 be optimizable (or blocks that appear to be mergeable), but which really | |
| 704 must be left untouched (they are required to make it safely across | |
| 705 partition boundaries). See the comments at the top of | |
| 706 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 707 | |
| 708 if (BB_PARTITION (a) != BB_PARTITION (b)) | |
| 709 return; | |
| 710 | |
| 711 real_b_end = BB_END (b); | |
| 712 | |
| 713 /* If there is a jump table following block B temporarily add the jump table | |
| 714 to block B so that it will also be moved to the correct location. */ | |
| 715 if (tablejump_p (BB_END (b), &label, &table) | |
| 716 && prev_active_insn (label) == BB_END (b)) | |
| 717 { | |
| 718 BB_END (b) = table; | |
| 719 } | |
| 720 | |
| 721 /* There had better have been a barrier there. Delete it. */ | |
| 722 barrier = NEXT_INSN (BB_END (b)); | |
| 723 if (barrier && BARRIER_P (barrier)) | |
| 724 delete_insn (barrier); | |
| 725 | |
| 726 | |
| 727 /* Scramble the insn chain. */ | |
| 728 reorder_insns_nobb (BB_HEAD (b), BB_END (b), BB_END (a)); | |
| 729 | |
| 730 /* Restore the real end of b. */ | |
| 731 BB_END (b) = real_b_end; | |
| 732 | |
| 733 if (dump_file) | |
| 734 fprintf (dump_file, "Moved block %d after %d and merged.\n", | |
| 735 b->index, a->index); | |
| 736 | |
| 737 /* Now blocks A and B are contiguous. Merge them. */ | |
| 738 merge_blocks (a, b); | |
| 739 } | |
| 740 | |
| 741 /* Attempt to merge basic blocks that are potentially non-adjacent. | |
| 742 Return NULL iff the attempt failed, otherwise return basic block | |
| 743 where cleanup_cfg should continue. Because the merging commonly | |
| 744 moves basic block away or introduces another optimization | |
| 745 possibility, return basic block just before B so cleanup_cfg don't | |
| 746 need to iterate. | |
| 747 | |
| 748 It may be good idea to return basic block before C in the case | |
| 749 C has been moved after B and originally appeared earlier in the | |
| 750 insn sequence, but we have no information available about the | |
| 751 relative ordering of these two. Hopefully it is not too common. */ | |
| 752 | |
| 753 static basic_block | |
| 754 merge_blocks_move (edge e, basic_block b, basic_block c, int mode) | |
| 755 { | |
| 756 basic_block next; | |
| 757 | |
| 758 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 759 mess up unconditional or indirect jumps that cross between hot | |
| 760 and cold sections. | |
| 761 | |
| 762 Basic block partitioning may result in some jumps that appear to | |
| 763 be optimizable (or blocks that appear to be mergeable), but which really | |
| 764 must be left untouched (they are required to make it safely across | |
| 765 partition boundaries). See the comments at the top of | |
| 766 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 767 | |
| 768 if (BB_PARTITION (b) != BB_PARTITION (c)) | |
| 769 return NULL; | |
| 770 | |
| 771 /* If B has a fallthru edge to C, no need to move anything. */ | |
| 772 if (e->flags & EDGE_FALLTHRU) | |
| 773 { | |
| 774 int b_index = b->index, c_index = c->index; | |
| 775 merge_blocks (b, c); | |
| 776 update_forwarder_flag (b); | |
| 777 | |
| 778 if (dump_file) | |
| 779 fprintf (dump_file, "Merged %d and %d without moving.\n", | |
| 780 b_index, c_index); | |
| 781 | |
| 782 return b->prev_bb == ENTRY_BLOCK_PTR ? b : b->prev_bb; | |
| 783 } | |
| 784 | |
| 785 /* Otherwise we will need to move code around. Do that only if expensive | |
| 786 transformations are allowed. */ | |
| 787 else if (mode & CLEANUP_EXPENSIVE) | |
| 788 { | |
| 789 edge tmp_edge, b_fallthru_edge; | |
| 790 bool c_has_outgoing_fallthru; | |
| 791 bool b_has_incoming_fallthru; | |
| 792 edge_iterator ei; | |
| 793 | |
| 794 /* Avoid overactive code motion, as the forwarder blocks should be | |
| 795 eliminated by edge redirection instead. One exception might have | |
| 796 been if B is a forwarder block and C has no fallthru edge, but | |
| 797 that should be cleaned up by bb-reorder instead. */ | |
| 798 if (FORWARDER_BLOCK_P (b) || FORWARDER_BLOCK_P (c)) | |
| 799 return NULL; | |
| 800 | |
| 801 /* We must make sure to not munge nesting of lexical blocks, | |
| 802 and loop notes. This is done by squeezing out all the notes | |
| 803 and leaving them there to lie. Not ideal, but functional. */ | |
| 804 | |
| 805 FOR_EACH_EDGE (tmp_edge, ei, c->succs) | |
| 806 if (tmp_edge->flags & EDGE_FALLTHRU) | |
| 807 break; | |
| 808 | |
| 809 c_has_outgoing_fallthru = (tmp_edge != NULL); | |
| 810 | |
| 811 FOR_EACH_EDGE (tmp_edge, ei, b->preds) | |
| 812 if (tmp_edge->flags & EDGE_FALLTHRU) | |
| 813 break; | |
| 814 | |
| 815 b_has_incoming_fallthru = (tmp_edge != NULL); | |
| 816 b_fallthru_edge = tmp_edge; | |
| 817 next = b->prev_bb; | |
| 818 if (next == c) | |
| 819 next = next->prev_bb; | |
| 820 | |
| 821 /* Otherwise, we're going to try to move C after B. If C does | |
| 822 not have an outgoing fallthru, then it can be moved | |
| 823 immediately after B without introducing or modifying jumps. */ | |
| 824 if (! c_has_outgoing_fallthru) | |
| 825 { | |
| 826 merge_blocks_move_successor_nojumps (b, c); | |
| 827 return next == ENTRY_BLOCK_PTR ? next->next_bb : next; | |
| 828 } | |
| 829 | |
| 830 /* If B does not have an incoming fallthru, then it can be moved | |
| 831 immediately before C without introducing or modifying jumps. | |
| 832 C cannot be the first block, so we do not have to worry about | |
| 833 accessing a non-existent block. */ | |
| 834 | |
| 835 if (b_has_incoming_fallthru) | |
| 836 { | |
| 837 basic_block bb; | |
| 838 | |
| 839 if (b_fallthru_edge->src == ENTRY_BLOCK_PTR) | |
| 840 return NULL; | |
| 841 bb = force_nonfallthru (b_fallthru_edge); | |
| 842 if (bb) | |
| 843 notice_new_block (bb); | |
| 844 } | |
| 845 | |
| 846 merge_blocks_move_predecessor_nojumps (b, c); | |
| 847 return next == ENTRY_BLOCK_PTR ? next->next_bb : next; | |
| 848 } | |
| 849 | |
| 850 return NULL; | |
| 851 } | |
| 852 | |
| 853 | |
| 854 /* Removes the memory attributes of MEM expression | |
| 855 if they are not equal. */ | |
| 856 | |
| 857 void | |
| 858 merge_memattrs (rtx x, rtx y) | |
| 859 { | |
| 860 int i; | |
| 861 int j; | |
| 862 enum rtx_code code; | |
| 863 const char *fmt; | |
| 864 | |
| 865 if (x == y) | |
| 866 return; | |
| 867 if (x == 0 || y == 0) | |
| 868 return; | |
| 869 | |
| 870 code = GET_CODE (x); | |
| 871 | |
| 872 if (code != GET_CODE (y)) | |
| 873 return; | |
| 874 | |
| 875 if (GET_MODE (x) != GET_MODE (y)) | |
| 876 return; | |
| 877 | |
| 878 if (code == MEM && MEM_ATTRS (x) != MEM_ATTRS (y)) | |
| 879 { | |
| 880 if (! MEM_ATTRS (x)) | |
| 881 MEM_ATTRS (y) = 0; | |
| 882 else if (! MEM_ATTRS (y)) | |
| 883 MEM_ATTRS (x) = 0; | |
| 884 else | |
| 885 { | |
| 886 rtx mem_size; | |
| 887 | |
| 888 if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y)) | |
| 889 { | |
| 890 set_mem_alias_set (x, 0); | |
| 891 set_mem_alias_set (y, 0); | |
| 892 } | |
| 893 | |
| 894 if (! mem_expr_equal_p (MEM_EXPR (x), MEM_EXPR (y))) | |
| 895 { | |
| 896 set_mem_expr (x, 0); | |
| 897 set_mem_expr (y, 0); | |
| 898 set_mem_offset (x, 0); | |
| 899 set_mem_offset (y, 0); | |
| 900 } | |
| 901 else if (MEM_OFFSET (x) != MEM_OFFSET (y)) | |
| 902 { | |
| 903 set_mem_offset (x, 0); | |
| 904 set_mem_offset (y, 0); | |
| 905 } | |
| 906 | |
| 907 if (!MEM_SIZE (x)) | |
| 908 mem_size = NULL_RTX; | |
| 909 else if (!MEM_SIZE (y)) | |
| 910 mem_size = NULL_RTX; | |
| 911 else | |
| 912 mem_size = GEN_INT (MAX (INTVAL (MEM_SIZE (x)), | |
| 913 INTVAL (MEM_SIZE (y)))); | |
| 914 set_mem_size (x, mem_size); | |
| 915 set_mem_size (y, mem_size); | |
| 916 | |
| 917 set_mem_align (x, MIN (MEM_ALIGN (x), MEM_ALIGN (y))); | |
| 918 set_mem_align (y, MEM_ALIGN (x)); | |
| 919 } | |
| 920 } | |
| 921 | |
| 922 fmt = GET_RTX_FORMAT (code); | |
| 923 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
| 924 { | |
| 925 switch (fmt[i]) | |
| 926 { | |
| 927 case 'E': | |
| 928 /* Two vectors must have the same length. */ | |
| 929 if (XVECLEN (x, i) != XVECLEN (y, i)) | |
| 930 return; | |
| 931 | |
| 932 for (j = 0; j < XVECLEN (x, i); j++) | |
| 933 merge_memattrs (XVECEXP (x, i, j), XVECEXP (y, i, j)); | |
| 934 | |
| 935 break; | |
| 936 | |
| 937 case 'e': | |
| 938 merge_memattrs (XEXP (x, i), XEXP (y, i)); | |
| 939 } | |
| 940 } | |
| 941 return; | |
| 942 } | |
| 943 | |
| 944 | |
| 945 /* Return true if I1 and I2 are equivalent and thus can be crossjumped. */ | |
| 946 | |
| 947 static bool | |
| 948 old_insns_match_p (int mode ATTRIBUTE_UNUSED, rtx i1, rtx i2) | |
| 949 { | |
| 950 rtx p1, p2; | |
| 951 | |
| 952 /* Verify that I1 and I2 are equivalent. */ | |
| 953 if (GET_CODE (i1) != GET_CODE (i2)) | |
| 954 return false; | |
| 955 | |
|
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956 /* __builtin_unreachable() may lead to empty blocks (ending with |
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957 NOTE_INSN_BASIC_BLOCK). They may be crossjumped. */ |
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958 if (NOTE_INSN_BASIC_BLOCK_P (i1) && NOTE_INSN_BASIC_BLOCK_P (i2)) |
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959 return true; |
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960 |
| 0 | 961 p1 = PATTERN (i1); |
| 962 p2 = PATTERN (i2); | |
| 963 | |
| 964 if (GET_CODE (p1) != GET_CODE (p2)) | |
| 965 return false; | |
| 966 | |
| 967 /* If this is a CALL_INSN, compare register usage information. | |
| 968 If we don't check this on stack register machines, the two | |
| 969 CALL_INSNs might be merged leaving reg-stack.c with mismatching | |
| 970 numbers of stack registers in the same basic block. | |
| 971 If we don't check this on machines with delay slots, a delay slot may | |
| 972 be filled that clobbers a parameter expected by the subroutine. | |
| 973 | |
| 974 ??? We take the simple route for now and assume that if they're | |
| 975 equal, they were constructed identically. */ | |
| 976 | |
| 977 if (CALL_P (i1) | |
| 978 && (!rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1), | |
| 979 CALL_INSN_FUNCTION_USAGE (i2)) | |
| 980 || SIBLING_CALL_P (i1) != SIBLING_CALL_P (i2))) | |
| 981 return false; | |
| 982 | |
| 983 #ifdef STACK_REGS | |
| 984 /* If cross_jump_death_matters is not 0, the insn's mode | |
| 985 indicates whether or not the insn contains any stack-like | |
| 986 regs. */ | |
| 987 | |
| 988 if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1)) | |
| 989 { | |
| 990 /* If register stack conversion has already been done, then | |
| 991 death notes must also be compared before it is certain that | |
| 992 the two instruction streams match. */ | |
| 993 | |
| 994 rtx note; | |
| 995 HARD_REG_SET i1_regset, i2_regset; | |
| 996 | |
| 997 CLEAR_HARD_REG_SET (i1_regset); | |
| 998 CLEAR_HARD_REG_SET (i2_regset); | |
| 999 | |
| 1000 for (note = REG_NOTES (i1); note; note = XEXP (note, 1)) | |
| 1001 if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) | |
| 1002 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0))); | |
| 1003 | |
| 1004 for (note = REG_NOTES (i2); note; note = XEXP (note, 1)) | |
| 1005 if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) | |
| 1006 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0))); | |
| 1007 | |
| 1008 if (!hard_reg_set_equal_p (i1_regset, i2_regset)) | |
| 1009 return false; | |
| 1010 } | |
| 1011 #endif | |
| 1012 | |
| 1013 if (reload_completed | |
| 1014 ? rtx_renumbered_equal_p (p1, p2) : rtx_equal_p (p1, p2)) | |
| 1015 return true; | |
| 1016 | |
| 1017 return false; | |
| 1018 } | |
| 1019 | |
| 1020 /* Look through the insns at the end of BB1 and BB2 and find the longest | |
| 1021 sequence that are equivalent. Store the first insns for that sequence | |
| 1022 in *F1 and *F2 and return the sequence length. | |
| 1023 | |
| 1024 To simplify callers of this function, if the blocks match exactly, | |
| 1025 store the head of the blocks in *F1 and *F2. */ | |
| 1026 | |
| 1027 static int | |
| 1028 flow_find_cross_jump (int mode ATTRIBUTE_UNUSED, basic_block bb1, | |
| 1029 basic_block bb2, rtx *f1, rtx *f2) | |
| 1030 { | |
| 1031 rtx i1, i2, last1, last2, afterlast1, afterlast2; | |
| 1032 int ninsns = 0; | |
| 1033 | |
| 1034 /* Skip simple jumps at the end of the blocks. Complex jumps still | |
| 1035 need to be compared for equivalence, which we'll do below. */ | |
| 1036 | |
| 1037 i1 = BB_END (bb1); | |
| 1038 last1 = afterlast1 = last2 = afterlast2 = NULL_RTX; | |
| 1039 if (onlyjump_p (i1) | |
| 1040 || (returnjump_p (i1) && !side_effects_p (PATTERN (i1)))) | |
| 1041 { | |
| 1042 last1 = i1; | |
| 1043 i1 = PREV_INSN (i1); | |
| 1044 } | |
| 1045 | |
| 1046 i2 = BB_END (bb2); | |
| 1047 if (onlyjump_p (i2) | |
| 1048 || (returnjump_p (i2) && !side_effects_p (PATTERN (i2)))) | |
| 1049 { | |
| 1050 last2 = i2; | |
| 1051 /* Count everything except for unconditional jump as insn. */ | |
| 1052 if (!simplejump_p (i2) && !returnjump_p (i2) && last1) | |
| 1053 ninsns++; | |
| 1054 i2 = PREV_INSN (i2); | |
| 1055 } | |
| 1056 | |
| 1057 while (true) | |
| 1058 { | |
| 1059 /* Ignore notes. */ | |
|
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1060 while (!NONDEBUG_INSN_P (i1) && i1 != BB_HEAD (bb1)) |
| 0 | 1061 i1 = PREV_INSN (i1); |
| 1062 | |
|
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1063 while (!NONDEBUG_INSN_P (i2) && i2 != BB_HEAD (bb2)) |
| 0 | 1064 i2 = PREV_INSN (i2); |
| 1065 | |
| 1066 if (i1 == BB_HEAD (bb1) || i2 == BB_HEAD (bb2)) | |
| 1067 break; | |
| 1068 | |
| 1069 if (!old_insns_match_p (mode, i1, i2)) | |
| 1070 break; | |
| 1071 | |
| 1072 merge_memattrs (i1, i2); | |
| 1073 | |
| 1074 /* Don't begin a cross-jump with a NOTE insn. */ | |
| 1075 if (INSN_P (i1)) | |
| 1076 { | |
| 1077 /* If the merged insns have different REG_EQUAL notes, then | |
| 1078 remove them. */ | |
| 1079 rtx equiv1 = find_reg_equal_equiv_note (i1); | |
| 1080 rtx equiv2 = find_reg_equal_equiv_note (i2); | |
| 1081 | |
| 1082 if (equiv1 && !equiv2) | |
| 1083 remove_note (i1, equiv1); | |
| 1084 else if (!equiv1 && equiv2) | |
| 1085 remove_note (i2, equiv2); | |
| 1086 else if (equiv1 && equiv2 | |
| 1087 && !rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0))) | |
| 1088 { | |
| 1089 remove_note (i1, equiv1); | |
| 1090 remove_note (i2, equiv2); | |
| 1091 } | |
| 1092 | |
| 1093 afterlast1 = last1, afterlast2 = last2; | |
| 1094 last1 = i1, last2 = i2; | |
| 1095 ninsns++; | |
| 1096 } | |
| 1097 | |
| 1098 i1 = PREV_INSN (i1); | |
| 1099 i2 = PREV_INSN (i2); | |
| 1100 } | |
| 1101 | |
| 1102 #ifdef HAVE_cc0 | |
| 1103 /* Don't allow the insn after a compare to be shared by | |
| 1104 cross-jumping unless the compare is also shared. */ | |
| 1105 if (ninsns && reg_mentioned_p (cc0_rtx, last1) && ! sets_cc0_p (last1)) | |
| 1106 last1 = afterlast1, last2 = afterlast2, ninsns--; | |
| 1107 #endif | |
| 1108 | |
| 1109 /* Include preceding notes and labels in the cross-jump. One, | |
| 1110 this may bring us to the head of the blocks as requested above. | |
| 1111 Two, it keeps line number notes as matched as may be. */ | |
| 1112 if (ninsns) | |
| 1113 { | |
|
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|
1114 while (last1 != BB_HEAD (bb1) && !NONDEBUG_INSN_P (PREV_INSN (last1))) |
| 0 | 1115 last1 = PREV_INSN (last1); |
| 1116 | |
| 1117 if (last1 != BB_HEAD (bb1) && LABEL_P (PREV_INSN (last1))) | |
| 1118 last1 = PREV_INSN (last1); | |
| 1119 | |
|
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ryoma <e075725@ie.u-ryukyu.ac.jp>
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0
diff
changeset
|
1120 while (last2 != BB_HEAD (bb2) && !NONDEBUG_INSN_P (PREV_INSN (last2))) |
| 0 | 1121 last2 = PREV_INSN (last2); |
| 1122 | |
| 1123 if (last2 != BB_HEAD (bb2) && LABEL_P (PREV_INSN (last2))) | |
| 1124 last2 = PREV_INSN (last2); | |
| 1125 | |
| 1126 *f1 = last1; | |
| 1127 *f2 = last2; | |
| 1128 } | |
| 1129 | |
| 1130 return ninsns; | |
| 1131 } | |
| 1132 | |
| 1133 /* Return true iff outgoing edges of BB1 and BB2 match, together with | |
| 1134 the branch instruction. This means that if we commonize the control | |
| 1135 flow before end of the basic block, the semantic remains unchanged. | |
| 1136 | |
| 1137 We may assume that there exists one edge with a common destination. */ | |
| 1138 | |
| 1139 static bool | |
| 1140 outgoing_edges_match (int mode, basic_block bb1, basic_block bb2) | |
| 1141 { | |
| 1142 int nehedges1 = 0, nehedges2 = 0; | |
| 1143 edge fallthru1 = 0, fallthru2 = 0; | |
| 1144 edge e1, e2; | |
| 1145 edge_iterator ei; | |
| 1146 | |
| 1147 /* If BB1 has only one successor, we may be looking at either an | |
| 1148 unconditional jump, or a fake edge to exit. */ | |
| 1149 if (single_succ_p (bb1) | |
| 1150 && (single_succ_edge (bb1)->flags & (EDGE_COMPLEX | EDGE_FAKE)) == 0 | |
| 1151 && (!JUMP_P (BB_END (bb1)) || simplejump_p (BB_END (bb1)))) | |
| 1152 return (single_succ_p (bb2) | |
| 1153 && (single_succ_edge (bb2)->flags | |
| 1154 & (EDGE_COMPLEX | EDGE_FAKE)) == 0 | |
| 1155 && (!JUMP_P (BB_END (bb2)) || simplejump_p (BB_END (bb2)))); | |
| 1156 | |
| 1157 /* Match conditional jumps - this may get tricky when fallthru and branch | |
| 1158 edges are crossed. */ | |
| 1159 if (EDGE_COUNT (bb1->succs) == 2 | |
| 1160 && any_condjump_p (BB_END (bb1)) | |
| 1161 && onlyjump_p (BB_END (bb1))) | |
| 1162 { | |
| 1163 edge b1, f1, b2, f2; | |
| 1164 bool reverse, match; | |
| 1165 rtx set1, set2, cond1, cond2; | |
| 1166 enum rtx_code code1, code2; | |
| 1167 | |
| 1168 if (EDGE_COUNT (bb2->succs) != 2 | |
| 1169 || !any_condjump_p (BB_END (bb2)) | |
| 1170 || !onlyjump_p (BB_END (bb2))) | |
| 1171 return false; | |
| 1172 | |
| 1173 b1 = BRANCH_EDGE (bb1); | |
| 1174 b2 = BRANCH_EDGE (bb2); | |
| 1175 f1 = FALLTHRU_EDGE (bb1); | |
| 1176 f2 = FALLTHRU_EDGE (bb2); | |
| 1177 | |
| 1178 /* Get around possible forwarders on fallthru edges. Other cases | |
| 1179 should be optimized out already. */ | |
| 1180 if (FORWARDER_BLOCK_P (f1->dest)) | |
| 1181 f1 = single_succ_edge (f1->dest); | |
| 1182 | |
| 1183 if (FORWARDER_BLOCK_P (f2->dest)) | |
| 1184 f2 = single_succ_edge (f2->dest); | |
| 1185 | |
| 1186 /* To simplify use of this function, return false if there are | |
| 1187 unneeded forwarder blocks. These will get eliminated later | |
| 1188 during cleanup_cfg. */ | |
| 1189 if (FORWARDER_BLOCK_P (f1->dest) | |
| 1190 || FORWARDER_BLOCK_P (f2->dest) | |
| 1191 || FORWARDER_BLOCK_P (b1->dest) | |
| 1192 || FORWARDER_BLOCK_P (b2->dest)) | |
| 1193 return false; | |
| 1194 | |
| 1195 if (f1->dest == f2->dest && b1->dest == b2->dest) | |
| 1196 reverse = false; | |
| 1197 else if (f1->dest == b2->dest && b1->dest == f2->dest) | |
| 1198 reverse = true; | |
| 1199 else | |
| 1200 return false; | |
| 1201 | |
| 1202 set1 = pc_set (BB_END (bb1)); | |
| 1203 set2 = pc_set (BB_END (bb2)); | |
| 1204 if ((XEXP (SET_SRC (set1), 1) == pc_rtx) | |
| 1205 != (XEXP (SET_SRC (set2), 1) == pc_rtx)) | |
| 1206 reverse = !reverse; | |
| 1207 | |
| 1208 cond1 = XEXP (SET_SRC (set1), 0); | |
| 1209 cond2 = XEXP (SET_SRC (set2), 0); | |
| 1210 code1 = GET_CODE (cond1); | |
| 1211 if (reverse) | |
| 1212 code2 = reversed_comparison_code (cond2, BB_END (bb2)); | |
| 1213 else | |
| 1214 code2 = GET_CODE (cond2); | |
| 1215 | |
| 1216 if (code2 == UNKNOWN) | |
| 1217 return false; | |
| 1218 | |
| 1219 /* Verify codes and operands match. */ | |
| 1220 match = ((code1 == code2 | |
| 1221 && rtx_renumbered_equal_p (XEXP (cond1, 0), XEXP (cond2, 0)) | |
| 1222 && rtx_renumbered_equal_p (XEXP (cond1, 1), XEXP (cond2, 1))) | |
| 1223 || (code1 == swap_condition (code2) | |
| 1224 && rtx_renumbered_equal_p (XEXP (cond1, 1), | |
| 1225 XEXP (cond2, 0)) | |
| 1226 && rtx_renumbered_equal_p (XEXP (cond1, 0), | |
| 1227 XEXP (cond2, 1)))); | |
| 1228 | |
| 1229 /* If we return true, we will join the blocks. Which means that | |
| 1230 we will only have one branch prediction bit to work with. Thus | |
| 1231 we require the existing branches to have probabilities that are | |
| 1232 roughly similar. */ | |
| 1233 if (match | |
| 1234 && optimize_bb_for_speed_p (bb1) | |
| 1235 && optimize_bb_for_speed_p (bb2)) | |
| 1236 { | |
| 1237 int prob2; | |
| 1238 | |
| 1239 if (b1->dest == b2->dest) | |
| 1240 prob2 = b2->probability; | |
| 1241 else | |
| 1242 /* Do not use f2 probability as f2 may be forwarded. */ | |
| 1243 prob2 = REG_BR_PROB_BASE - b2->probability; | |
| 1244 | |
| 1245 /* Fail if the difference in probabilities is greater than 50%. | |
| 1246 This rules out two well-predicted branches with opposite | |
| 1247 outcomes. */ | |
| 1248 if (abs (b1->probability - prob2) > REG_BR_PROB_BASE / 2) | |
| 1249 { | |
| 1250 if (dump_file) | |
| 1251 fprintf (dump_file, | |
| 1252 "Outcomes of branch in bb %i and %i differ too much (%i %i)\n", | |
| 1253 bb1->index, bb2->index, b1->probability, prob2); | |
| 1254 | |
| 1255 return false; | |
| 1256 } | |
| 1257 } | |
| 1258 | |
| 1259 if (dump_file && match) | |
| 1260 fprintf (dump_file, "Conditionals in bb %i and %i match.\n", | |
| 1261 bb1->index, bb2->index); | |
| 1262 | |
| 1263 return match; | |
| 1264 } | |
| 1265 | |
| 1266 /* Generic case - we are seeing a computed jump, table jump or trapping | |
| 1267 instruction. */ | |
| 1268 | |
| 1269 /* Check whether there are tablejumps in the end of BB1 and BB2. | |
| 1270 Return true if they are identical. */ | |
| 1271 { | |
| 1272 rtx label1, label2; | |
| 1273 rtx table1, table2; | |
| 1274 | |
| 1275 if (tablejump_p (BB_END (bb1), &label1, &table1) | |
| 1276 && tablejump_p (BB_END (bb2), &label2, &table2) | |
| 1277 && GET_CODE (PATTERN (table1)) == GET_CODE (PATTERN (table2))) | |
| 1278 { | |
| 1279 /* The labels should never be the same rtx. If they really are same | |
| 1280 the jump tables are same too. So disable crossjumping of blocks BB1 | |
| 1281 and BB2 because when deleting the common insns in the end of BB1 | |
| 1282 by delete_basic_block () the jump table would be deleted too. */ | |
| 1283 /* If LABEL2 is referenced in BB1->END do not do anything | |
| 1284 because we would loose information when replacing | |
| 1285 LABEL1 by LABEL2 and then LABEL2 by LABEL1 in BB1->END. */ | |
| 1286 if (label1 != label2 && !rtx_referenced_p (label2, BB_END (bb1))) | |
| 1287 { | |
| 1288 /* Set IDENTICAL to true when the tables are identical. */ | |
| 1289 bool identical = false; | |
| 1290 rtx p1, p2; | |
| 1291 | |
| 1292 p1 = PATTERN (table1); | |
| 1293 p2 = PATTERN (table2); | |
| 1294 if (GET_CODE (p1) == ADDR_VEC && rtx_equal_p (p1, p2)) | |
| 1295 { | |
| 1296 identical = true; | |
| 1297 } | |
| 1298 else if (GET_CODE (p1) == ADDR_DIFF_VEC | |
| 1299 && (XVECLEN (p1, 1) == XVECLEN (p2, 1)) | |
| 1300 && rtx_equal_p (XEXP (p1, 2), XEXP (p2, 2)) | |
| 1301 && rtx_equal_p (XEXP (p1, 3), XEXP (p2, 3))) | |
| 1302 { | |
| 1303 int i; | |
| 1304 | |
| 1305 identical = true; | |
| 1306 for (i = XVECLEN (p1, 1) - 1; i >= 0 && identical; i--) | |
| 1307 if (!rtx_equal_p (XVECEXP (p1, 1, i), XVECEXP (p2, 1, i))) | |
| 1308 identical = false; | |
| 1309 } | |
| 1310 | |
| 1311 if (identical) | |
| 1312 { | |
| 1313 replace_label_data rr; | |
| 1314 bool match; | |
| 1315 | |
| 1316 /* Temporarily replace references to LABEL1 with LABEL2 | |
| 1317 in BB1->END so that we could compare the instructions. */ | |
| 1318 rr.r1 = label1; | |
| 1319 rr.r2 = label2; | |
| 1320 rr.update_label_nuses = false; | |
| 1321 for_each_rtx (&BB_END (bb1), replace_label, &rr); | |
| 1322 | |
| 1323 match = old_insns_match_p (mode, BB_END (bb1), BB_END (bb2)); | |
| 1324 if (dump_file && match) | |
| 1325 fprintf (dump_file, | |
| 1326 "Tablejumps in bb %i and %i match.\n", | |
| 1327 bb1->index, bb2->index); | |
| 1328 | |
| 1329 /* Set the original label in BB1->END because when deleting | |
| 1330 a block whose end is a tablejump, the tablejump referenced | |
| 1331 from the instruction is deleted too. */ | |
| 1332 rr.r1 = label2; | |
| 1333 rr.r2 = label1; | |
| 1334 for_each_rtx (&BB_END (bb1), replace_label, &rr); | |
| 1335 | |
| 1336 return match; | |
| 1337 } | |
| 1338 } | |
| 1339 return false; | |
| 1340 } | |
| 1341 } | |
| 1342 | |
| 1343 /* First ensure that the instructions match. There may be many outgoing | |
| 1344 edges so this test is generally cheaper. */ | |
| 1345 if (!old_insns_match_p (mode, BB_END (bb1), BB_END (bb2))) | |
| 1346 return false; | |
| 1347 | |
| 1348 /* Search the outgoing edges, ensure that the counts do match, find possible | |
| 1349 fallthru and exception handling edges since these needs more | |
| 1350 validation. */ | |
| 1351 if (EDGE_COUNT (bb1->succs) != EDGE_COUNT (bb2->succs)) | |
| 1352 return false; | |
| 1353 | |
| 1354 FOR_EACH_EDGE (e1, ei, bb1->succs) | |
| 1355 { | |
| 1356 e2 = EDGE_SUCC (bb2, ei.index); | |
| 1357 | |
| 1358 if (e1->flags & EDGE_EH) | |
| 1359 nehedges1++; | |
| 1360 | |
| 1361 if (e2->flags & EDGE_EH) | |
| 1362 nehedges2++; | |
| 1363 | |
| 1364 if (e1->flags & EDGE_FALLTHRU) | |
| 1365 fallthru1 = e1; | |
| 1366 if (e2->flags & EDGE_FALLTHRU) | |
| 1367 fallthru2 = e2; | |
| 1368 } | |
| 1369 | |
| 1370 /* If number of edges of various types does not match, fail. */ | |
| 1371 if (nehedges1 != nehedges2 | |
| 1372 || (fallthru1 != 0) != (fallthru2 != 0)) | |
| 1373 return false; | |
| 1374 | |
| 1375 /* fallthru edges must be forwarded to the same destination. */ | |
| 1376 if (fallthru1) | |
| 1377 { | |
| 1378 basic_block d1 = (forwarder_block_p (fallthru1->dest) | |
| 1379 ? single_succ (fallthru1->dest): fallthru1->dest); | |
| 1380 basic_block d2 = (forwarder_block_p (fallthru2->dest) | |
| 1381 ? single_succ (fallthru2->dest): fallthru2->dest); | |
| 1382 | |
| 1383 if (d1 != d2) | |
| 1384 return false; | |
| 1385 } | |
| 1386 | |
| 1387 /* Ensure the same EH region. */ | |
| 1388 { | |
| 1389 rtx n1 = find_reg_note (BB_END (bb1), REG_EH_REGION, 0); | |
| 1390 rtx n2 = find_reg_note (BB_END (bb2), REG_EH_REGION, 0); | |
| 1391 | |
| 1392 if (!n1 && n2) | |
| 1393 return false; | |
| 1394 | |
| 1395 if (n1 && (!n2 || XEXP (n1, 0) != XEXP (n2, 0))) | |
| 1396 return false; | |
| 1397 } | |
| 1398 | |
| 1399 /* The same checks as in try_crossjump_to_edge. It is required for RTL | |
| 1400 version of sequence abstraction. */ | |
| 1401 FOR_EACH_EDGE (e1, ei, bb2->succs) | |
| 1402 { | |
| 1403 edge e2; | |
| 1404 edge_iterator ei; | |
| 1405 basic_block d1 = e1->dest; | |
| 1406 | |
| 1407 if (FORWARDER_BLOCK_P (d1)) | |
| 1408 d1 = EDGE_SUCC (d1, 0)->dest; | |
| 1409 | |
| 1410 FOR_EACH_EDGE (e2, ei, bb1->succs) | |
| 1411 { | |
| 1412 basic_block d2 = e2->dest; | |
| 1413 if (FORWARDER_BLOCK_P (d2)) | |
| 1414 d2 = EDGE_SUCC (d2, 0)->dest; | |
| 1415 if (d1 == d2) | |
| 1416 break; | |
| 1417 } | |
| 1418 | |
| 1419 if (!e2) | |
| 1420 return false; | |
| 1421 } | |
| 1422 | |
| 1423 return true; | |
| 1424 } | |
| 1425 | |
| 1426 /* Returns true if BB basic block has a preserve label. */ | |
| 1427 | |
| 1428 static bool | |
| 1429 block_has_preserve_label (basic_block bb) | |
| 1430 { | |
| 1431 return (bb | |
| 1432 && block_label (bb) | |
| 1433 && LABEL_PRESERVE_P (block_label (bb))); | |
| 1434 } | |
| 1435 | |
| 1436 /* E1 and E2 are edges with the same destination block. Search their | |
| 1437 predecessors for common code. If found, redirect control flow from | |
| 1438 (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC. */ | |
| 1439 | |
| 1440 static bool | |
| 1441 try_crossjump_to_edge (int mode, edge e1, edge e2) | |
| 1442 { | |
| 1443 int nmatch; | |
| 1444 basic_block src1 = e1->src, src2 = e2->src; | |
| 1445 basic_block redirect_to, redirect_from, to_remove; | |
| 1446 rtx newpos1, newpos2; | |
| 1447 edge s; | |
| 1448 edge_iterator ei; | |
| 1449 | |
| 1450 newpos1 = newpos2 = NULL_RTX; | |
| 1451 | |
| 1452 /* If we have partitioned hot/cold basic blocks, it is a bad idea | |
| 1453 to try this optimization. | |
| 1454 | |
| 1455 Basic block partitioning may result in some jumps that appear to | |
| 1456 be optimizable (or blocks that appear to be mergeable), but which really | |
| 1457 must be left untouched (they are required to make it safely across | |
| 1458 partition boundaries). See the comments at the top of | |
| 1459 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 1460 | |
| 1461 if (flag_reorder_blocks_and_partition && reload_completed) | |
| 1462 return false; | |
| 1463 | |
| 1464 /* Search backward through forwarder blocks. We don't need to worry | |
| 1465 about multiple entry or chained forwarders, as they will be optimized | |
| 1466 away. We do this to look past the unconditional jump following a | |
| 1467 conditional jump that is required due to the current CFG shape. */ | |
| 1468 if (single_pred_p (src1) | |
| 1469 && FORWARDER_BLOCK_P (src1)) | |
| 1470 e1 = single_pred_edge (src1), src1 = e1->src; | |
| 1471 | |
| 1472 if (single_pred_p (src2) | |
| 1473 && FORWARDER_BLOCK_P (src2)) | |
| 1474 e2 = single_pred_edge (src2), src2 = e2->src; | |
| 1475 | |
| 1476 /* Nothing to do if we reach ENTRY, or a common source block. */ | |
| 1477 if (src1 == ENTRY_BLOCK_PTR || src2 == ENTRY_BLOCK_PTR) | |
| 1478 return false; | |
| 1479 if (src1 == src2) | |
| 1480 return false; | |
| 1481 | |
| 1482 /* Seeing more than 1 forwarder blocks would confuse us later... */ | |
| 1483 if (FORWARDER_BLOCK_P (e1->dest) | |
| 1484 && FORWARDER_BLOCK_P (single_succ (e1->dest))) | |
| 1485 return false; | |
| 1486 | |
| 1487 if (FORWARDER_BLOCK_P (e2->dest) | |
| 1488 && FORWARDER_BLOCK_P (single_succ (e2->dest))) | |
| 1489 return false; | |
| 1490 | |
| 1491 /* Likewise with dead code (possibly newly created by the other optimizations | |
| 1492 of cfg_cleanup). */ | |
| 1493 if (EDGE_COUNT (src1->preds) == 0 || EDGE_COUNT (src2->preds) == 0) | |
| 1494 return false; | |
| 1495 | |
| 1496 /* Look for the common insn sequence, part the first ... */ | |
| 1497 if (!outgoing_edges_match (mode, src1, src2)) | |
| 1498 return false; | |
| 1499 | |
| 1500 /* ... and part the second. */ | |
| 1501 nmatch = flow_find_cross_jump (mode, src1, src2, &newpos1, &newpos2); | |
| 1502 | |
| 1503 /* Don't proceed with the crossjump unless we found a sufficient number | |
| 1504 of matching instructions or the 'from' block was totally matched | |
| 1505 (such that its predecessors will hopefully be redirected and the | |
| 1506 block removed). */ | |
| 1507 if ((nmatch < PARAM_VALUE (PARAM_MIN_CROSSJUMP_INSNS)) | |
| 1508 && (newpos1 != BB_HEAD (src1))) | |
| 1509 return false; | |
| 1510 | |
| 1511 /* Avoid deleting preserve label when redirecting ABNORMAL edges. */ | |
| 1512 if (block_has_preserve_label (e1->dest) | |
| 1513 && (e1->flags & EDGE_ABNORMAL)) | |
| 1514 return false; | |
| 1515 | |
| 1516 /* Here we know that the insns in the end of SRC1 which are common with SRC2 | |
| 1517 will be deleted. | |
| 1518 If we have tablejumps in the end of SRC1 and SRC2 | |
| 1519 they have been already compared for equivalence in outgoing_edges_match () | |
| 1520 so replace the references to TABLE1 by references to TABLE2. */ | |
| 1521 { | |
| 1522 rtx label1, label2; | |
| 1523 rtx table1, table2; | |
| 1524 | |
| 1525 if (tablejump_p (BB_END (src1), &label1, &table1) | |
| 1526 && tablejump_p (BB_END (src2), &label2, &table2) | |
| 1527 && label1 != label2) | |
| 1528 { | |
| 1529 replace_label_data rr; | |
| 1530 rtx insn; | |
| 1531 | |
| 1532 /* Replace references to LABEL1 with LABEL2. */ | |
| 1533 rr.r1 = label1; | |
| 1534 rr.r2 = label2; | |
| 1535 rr.update_label_nuses = true; | |
| 1536 for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) | |
| 1537 { | |
| 1538 /* Do not replace the label in SRC1->END because when deleting | |
| 1539 a block whose end is a tablejump, the tablejump referenced | |
| 1540 from the instruction is deleted too. */ | |
| 1541 if (insn != BB_END (src1)) | |
| 1542 for_each_rtx (&insn, replace_label, &rr); | |
| 1543 } | |
| 1544 } | |
| 1545 } | |
| 1546 | |
| 1547 /* Avoid splitting if possible. We must always split when SRC2 has | |
| 1548 EH predecessor edges, or we may end up with basic blocks with both | |
| 1549 normal and EH predecessor edges. */ | |
| 1550 if (newpos2 == BB_HEAD (src2) | |
| 1551 && !(EDGE_PRED (src2, 0)->flags & EDGE_EH)) | |
| 1552 redirect_to = src2; | |
| 1553 else | |
| 1554 { | |
| 1555 if (newpos2 == BB_HEAD (src2)) | |
| 1556 { | |
| 1557 /* Skip possible basic block header. */ | |
| 1558 if (LABEL_P (newpos2)) | |
| 1559 newpos2 = NEXT_INSN (newpos2); | |
|
55
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
1560 while (DEBUG_INSN_P (newpos2)) |
|
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1561 newpos2 = NEXT_INSN (newpos2); |
| 0 | 1562 if (NOTE_P (newpos2)) |
| 1563 newpos2 = NEXT_INSN (newpos2); | |
|
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1564 while (DEBUG_INSN_P (newpos2)) |
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1565 newpos2 = NEXT_INSN (newpos2); |
| 0 | 1566 } |
| 1567 | |
| 1568 if (dump_file) | |
| 1569 fprintf (dump_file, "Splitting bb %i before %i insns\n", | |
| 1570 src2->index, nmatch); | |
| 1571 redirect_to = split_block (src2, PREV_INSN (newpos2))->dest; | |
| 1572 } | |
| 1573 | |
| 1574 if (dump_file) | |
| 1575 fprintf (dump_file, | |
| 1576 "Cross jumping from bb %i to bb %i; %i common insns\n", | |
| 1577 src1->index, src2->index, nmatch); | |
| 1578 | |
| 1579 /* We may have some registers visible through the block. */ | |
| 1580 df_set_bb_dirty (redirect_to); | |
| 1581 | |
| 1582 /* Recompute the frequencies and counts of outgoing edges. */ | |
| 1583 FOR_EACH_EDGE (s, ei, redirect_to->succs) | |
| 1584 { | |
| 1585 edge s2; | |
| 1586 edge_iterator ei; | |
| 1587 basic_block d = s->dest; | |
| 1588 | |
| 1589 if (FORWARDER_BLOCK_P (d)) | |
| 1590 d = single_succ (d); | |
| 1591 | |
| 1592 FOR_EACH_EDGE (s2, ei, src1->succs) | |
| 1593 { | |
| 1594 basic_block d2 = s2->dest; | |
| 1595 if (FORWARDER_BLOCK_P (d2)) | |
| 1596 d2 = single_succ (d2); | |
| 1597 if (d == d2) | |
| 1598 break; | |
| 1599 } | |
| 1600 | |
| 1601 s->count += s2->count; | |
| 1602 | |
| 1603 /* Take care to update possible forwarder blocks. We verified | |
| 1604 that there is no more than one in the chain, so we can't run | |
| 1605 into infinite loop. */ | |
| 1606 if (FORWARDER_BLOCK_P (s->dest)) | |
| 1607 { | |
| 1608 single_succ_edge (s->dest)->count += s2->count; | |
| 1609 s->dest->count += s2->count; | |
| 1610 s->dest->frequency += EDGE_FREQUENCY (s); | |
| 1611 } | |
| 1612 | |
| 1613 if (FORWARDER_BLOCK_P (s2->dest)) | |
| 1614 { | |
| 1615 single_succ_edge (s2->dest)->count -= s2->count; | |
| 1616 if (single_succ_edge (s2->dest)->count < 0) | |
| 1617 single_succ_edge (s2->dest)->count = 0; | |
| 1618 s2->dest->count -= s2->count; | |
| 1619 s2->dest->frequency -= EDGE_FREQUENCY (s); | |
| 1620 if (s2->dest->frequency < 0) | |
| 1621 s2->dest->frequency = 0; | |
| 1622 if (s2->dest->count < 0) | |
| 1623 s2->dest->count = 0; | |
| 1624 } | |
| 1625 | |
| 1626 if (!redirect_to->frequency && !src1->frequency) | |
| 1627 s->probability = (s->probability + s2->probability) / 2; | |
| 1628 else | |
| 1629 s->probability | |
| 1630 = ((s->probability * redirect_to->frequency + | |
| 1631 s2->probability * src1->frequency) | |
| 1632 / (redirect_to->frequency + src1->frequency)); | |
| 1633 } | |
| 1634 | |
| 1635 /* Adjust count and frequency for the block. An earlier jump | |
| 1636 threading pass may have left the profile in an inconsistent | |
| 1637 state (see update_bb_profile_for_threading) so we must be | |
| 1638 prepared for overflows. */ | |
| 1639 redirect_to->count += src1->count; | |
| 1640 redirect_to->frequency += src1->frequency; | |
| 1641 if (redirect_to->frequency > BB_FREQ_MAX) | |
| 1642 redirect_to->frequency = BB_FREQ_MAX; | |
| 1643 update_br_prob_note (redirect_to); | |
| 1644 | |
| 1645 /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */ | |
| 1646 | |
| 1647 /* Skip possible basic block header. */ | |
| 1648 if (LABEL_P (newpos1)) | |
| 1649 newpos1 = NEXT_INSN (newpos1); | |
| 1650 | |
|
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1651 while (DEBUG_INSN_P (newpos1)) |
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1652 newpos1 = NEXT_INSN (newpos1); |
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1653 |
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1654 if (NOTE_INSN_BASIC_BLOCK_P (newpos1)) |
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1655 newpos1 = NEXT_INSN (newpos1); |
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1656 |
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1657 while (DEBUG_INSN_P (newpos1)) |
| 0 | 1658 newpos1 = NEXT_INSN (newpos1); |
| 1659 | |
| 1660 redirect_from = split_block (src1, PREV_INSN (newpos1))->src; | |
| 1661 to_remove = single_succ (redirect_from); | |
| 1662 | |
| 1663 redirect_edge_and_branch_force (single_succ_edge (redirect_from), redirect_to); | |
| 1664 delete_basic_block (to_remove); | |
| 1665 | |
| 1666 update_forwarder_flag (redirect_from); | |
| 1667 if (redirect_to != src2) | |
| 1668 update_forwarder_flag (src2); | |
| 1669 | |
| 1670 return true; | |
| 1671 } | |
| 1672 | |
| 1673 /* Search the predecessors of BB for common insn sequences. When found, | |
| 1674 share code between them by redirecting control flow. Return true if | |
| 1675 any changes made. */ | |
| 1676 | |
| 1677 static bool | |
| 1678 try_crossjump_bb (int mode, basic_block bb) | |
| 1679 { | |
| 1680 edge e, e2, fallthru; | |
| 1681 bool changed; | |
| 1682 unsigned max, ix, ix2; | |
| 1683 basic_block ev, ev2; | |
| 1684 edge_iterator ei; | |
| 1685 | |
| 1686 /* Nothing to do if there is not at least two incoming edges. */ | |
| 1687 if (EDGE_COUNT (bb->preds) < 2) | |
| 1688 return false; | |
| 1689 | |
| 1690 /* Don't crossjump if this block ends in a computed jump, | |
| 1691 unless we are optimizing for size. */ | |
| 1692 if (optimize_bb_for_size_p (bb) | |
| 1693 && bb != EXIT_BLOCK_PTR | |
| 1694 && computed_jump_p (BB_END (bb))) | |
| 1695 return false; | |
| 1696 | |
| 1697 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 1698 mess up unconditional or indirect jumps that cross between hot | |
| 1699 and cold sections. | |
| 1700 | |
| 1701 Basic block partitioning may result in some jumps that appear to | |
| 1702 be optimizable (or blocks that appear to be mergeable), but which really | |
| 1703 must be left untouched (they are required to make it safely across | |
| 1704 partition boundaries). See the comments at the top of | |
| 1705 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 1706 | |
| 1707 if (BB_PARTITION (EDGE_PRED (bb, 0)->src) != | |
| 1708 BB_PARTITION (EDGE_PRED (bb, 1)->src) | |
| 1709 || (EDGE_PRED (bb, 0)->flags & EDGE_CROSSING)) | |
| 1710 return false; | |
| 1711 | |
| 1712 /* It is always cheapest to redirect a block that ends in a branch to | |
| 1713 a block that falls through into BB, as that adds no branches to the | |
| 1714 program. We'll try that combination first. */ | |
| 1715 fallthru = NULL; | |
| 1716 max = PARAM_VALUE (PARAM_MAX_CROSSJUMP_EDGES); | |
| 1717 | |
| 1718 if (EDGE_COUNT (bb->preds) > max) | |
| 1719 return false; | |
| 1720 | |
| 1721 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 1722 { | |
| 1723 if (e->flags & EDGE_FALLTHRU) | |
| 1724 { | |
| 1725 fallthru = e; | |
| 1726 break; | |
| 1727 } | |
| 1728 } | |
| 1729 | |
| 1730 changed = false; | |
| 1731 for (ix = 0, ev = bb; ix < EDGE_COUNT (ev->preds); ) | |
| 1732 { | |
| 1733 e = EDGE_PRED (ev, ix); | |
| 1734 ix++; | |
| 1735 | |
| 1736 /* As noted above, first try with the fallthru predecessor (or, a | |
| 1737 fallthru predecessor if we are in cfglayout mode). */ | |
| 1738 if (fallthru) | |
| 1739 { | |
| 1740 /* Don't combine the fallthru edge into anything else. | |
| 1741 If there is a match, we'll do it the other way around. */ | |
| 1742 if (e == fallthru) | |
| 1743 continue; | |
| 1744 /* If nothing changed since the last attempt, there is nothing | |
| 1745 we can do. */ | |
| 1746 if (!first_pass | |
| 1747 && (!(df_get_bb_dirty (e->src)) | |
| 1748 && !(df_get_bb_dirty (fallthru->src)))) | |
| 1749 continue; | |
| 1750 | |
| 1751 if (try_crossjump_to_edge (mode, e, fallthru)) | |
| 1752 { | |
| 1753 changed = true; | |
| 1754 ix = 0; | |
| 1755 ev = bb; | |
| 1756 continue; | |
| 1757 } | |
| 1758 } | |
| 1759 | |
| 1760 /* Non-obvious work limiting check: Recognize that we're going | |
| 1761 to call try_crossjump_bb on every basic block. So if we have | |
| 1762 two blocks with lots of outgoing edges (a switch) and they | |
| 1763 share lots of common destinations, then we would do the | |
| 1764 cross-jump check once for each common destination. | |
| 1765 | |
| 1766 Now, if the blocks actually are cross-jump candidates, then | |
| 1767 all of their destinations will be shared. Which means that | |
| 1768 we only need check them for cross-jump candidacy once. We | |
| 1769 can eliminate redundant checks of crossjump(A,B) by arbitrarily | |
| 1770 choosing to do the check from the block for which the edge | |
| 1771 in question is the first successor of A. */ | |
| 1772 if (EDGE_SUCC (e->src, 0) != e) | |
| 1773 continue; | |
| 1774 | |
| 1775 for (ix2 = 0, ev2 = bb; ix2 < EDGE_COUNT (ev2->preds); ) | |
| 1776 { | |
| 1777 e2 = EDGE_PRED (ev2, ix2); | |
| 1778 ix2++; | |
| 1779 | |
| 1780 if (e2 == e) | |
| 1781 continue; | |
| 1782 | |
| 1783 /* We've already checked the fallthru edge above. */ | |
| 1784 if (e2 == fallthru) | |
| 1785 continue; | |
| 1786 | |
| 1787 /* The "first successor" check above only prevents multiple | |
| 1788 checks of crossjump(A,B). In order to prevent redundant | |
| 1789 checks of crossjump(B,A), require that A be the block | |
| 1790 with the lowest index. */ | |
| 1791 if (e->src->index > e2->src->index) | |
| 1792 continue; | |
| 1793 | |
| 1794 /* If nothing changed since the last attempt, there is nothing | |
| 1795 we can do. */ | |
| 1796 if (!first_pass | |
| 1797 && (!(df_get_bb_dirty (e->src)) | |
| 1798 && !(df_get_bb_dirty (e2->src)))) | |
| 1799 continue; | |
| 1800 | |
| 1801 if (try_crossjump_to_edge (mode, e, e2)) | |
| 1802 { | |
| 1803 changed = true; | |
| 1804 ev2 = bb; | |
| 1805 ix = 0; | |
| 1806 break; | |
| 1807 } | |
| 1808 } | |
| 1809 } | |
| 1810 | |
| 1811 if (changed) | |
| 1812 crossjumps_occured = true; | |
| 1813 | |
| 1814 return changed; | |
| 1815 } | |
| 1816 | |
|
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1817 /* Return true if BB contains just bb note, or bb note followed |
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1818 by only DEBUG_INSNs. */ |
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1819 |
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1820 static bool |
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1821 trivially_empty_bb_p (basic_block bb) |
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1822 { |
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1823 rtx insn = BB_END (bb); |
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1824 |
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1825 while (1) |
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1826 { |
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1827 if (insn == BB_HEAD (bb)) |
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1828 return true; |
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1829 if (!DEBUG_INSN_P (insn)) |
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1830 return false; |
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1831 insn = PREV_INSN (insn); |
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1832 } |
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1833 } |
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1834 |
| 0 | 1835 /* Do simple CFG optimizations - basic block merging, simplifying of jump |
| 1836 instructions etc. Return nonzero if changes were made. */ | |
| 1837 | |
| 1838 static bool | |
| 1839 try_optimize_cfg (int mode) | |
| 1840 { | |
| 1841 bool changed_overall = false; | |
| 1842 bool changed; | |
| 1843 int iterations = 0; | |
| 1844 basic_block bb, b, next; | |
| 1845 | |
| 1846 if (mode & (CLEANUP_CROSSJUMP | CLEANUP_THREADING)) | |
| 1847 clear_bb_flags (); | |
| 1848 | |
| 1849 crossjumps_occured = false; | |
| 1850 | |
| 1851 FOR_EACH_BB (bb) | |
| 1852 update_forwarder_flag (bb); | |
| 1853 | |
| 1854 if (! targetm.cannot_modify_jumps_p ()) | |
| 1855 { | |
| 1856 first_pass = true; | |
| 1857 /* Attempt to merge blocks as made possible by edge removal. If | |
| 1858 a block has only one successor, and the successor has only | |
| 1859 one predecessor, they may be combined. */ | |
| 1860 do | |
| 1861 { | |
| 1862 changed = false; | |
| 1863 iterations++; | |
| 1864 | |
| 1865 if (dump_file) | |
| 1866 fprintf (dump_file, | |
| 1867 "\n\ntry_optimize_cfg iteration %i\n\n", | |
| 1868 iterations); | |
| 1869 | |
| 1870 for (b = ENTRY_BLOCK_PTR->next_bb; b != EXIT_BLOCK_PTR;) | |
| 1871 { | |
| 1872 basic_block c; | |
| 1873 edge s; | |
| 1874 bool changed_here = false; | |
| 1875 | |
|
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1876 /* Delete trivially dead basic blocks. This is either |
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1877 blocks with no predecessors, or empty blocks with no |
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1878 successors. However if the empty block with no |
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1879 successors is the successor of the ENTRY_BLOCK, it is |
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1880 kept. This ensures that the ENTRY_BLOCK will have a |
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1881 successor which is a precondition for many RTL |
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1882 passes. Empty blocks may result from expanding |
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1883 __builtin_unreachable (). */ |
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1884 if (EDGE_COUNT (b->preds) == 0 |
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1885 || (EDGE_COUNT (b->succs) == 0 |
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1886 && trivially_empty_bb_p (b) |
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1887 && single_succ_edge (ENTRY_BLOCK_PTR)->dest != b)) |
| 0 | 1888 { |
| 1889 c = b->prev_bb; | |
| 1890 delete_basic_block (b); | |
| 1891 if (!(mode & CLEANUP_CFGLAYOUT)) | |
| 1892 changed = true; | |
| 1893 /* Avoid trying to remove ENTRY_BLOCK_PTR. */ | |
| 1894 b = (c == ENTRY_BLOCK_PTR ? c->next_bb : c); | |
| 1895 continue; | |
| 1896 } | |
| 1897 | |
| 1898 /* Remove code labels no longer used. */ | |
| 1899 if (single_pred_p (b) | |
| 1900 && (single_pred_edge (b)->flags & EDGE_FALLTHRU) | |
| 1901 && !(single_pred_edge (b)->flags & EDGE_COMPLEX) | |
| 1902 && LABEL_P (BB_HEAD (b)) | |
| 1903 /* If the previous block ends with a branch to this | |
| 1904 block, we can't delete the label. Normally this | |
| 1905 is a condjump that is yet to be simplified, but | |
| 1906 if CASE_DROPS_THRU, this can be a tablejump with | |
| 1907 some element going to the same place as the | |
| 1908 default (fallthru). */ | |
| 1909 && (single_pred (b) == ENTRY_BLOCK_PTR | |
| 1910 || !JUMP_P (BB_END (single_pred (b))) | |
| 1911 || ! label_is_jump_target_p (BB_HEAD (b), | |
| 1912 BB_END (single_pred (b))))) | |
| 1913 { | |
| 1914 rtx label = BB_HEAD (b); | |
| 1915 | |
| 1916 delete_insn_chain (label, label, false); | |
| 1917 /* If the case label is undeletable, move it after the | |
| 1918 BASIC_BLOCK note. */ | |
| 1919 if (NOTE_KIND (BB_HEAD (b)) == NOTE_INSN_DELETED_LABEL) | |
| 1920 { | |
| 1921 rtx bb_note = NEXT_INSN (BB_HEAD (b)); | |
| 1922 | |
| 1923 reorder_insns_nobb (label, label, bb_note); | |
| 1924 BB_HEAD (b) = bb_note; | |
| 1925 if (BB_END (b) == bb_note) | |
| 1926 BB_END (b) = label; | |
| 1927 } | |
| 1928 if (dump_file) | |
| 1929 fprintf (dump_file, "Deleted label in block %i.\n", | |
| 1930 b->index); | |
| 1931 } | |
| 1932 | |
| 1933 /* If we fall through an empty block, we can remove it. */ | |
| 1934 if (!(mode & CLEANUP_CFGLAYOUT) | |
| 1935 && single_pred_p (b) | |
| 1936 && (single_pred_edge (b)->flags & EDGE_FALLTHRU) | |
| 1937 && !LABEL_P (BB_HEAD (b)) | |
| 1938 && FORWARDER_BLOCK_P (b) | |
| 1939 /* Note that forwarder_block_p true ensures that | |
| 1940 there is a successor for this block. */ | |
| 1941 && (single_succ_edge (b)->flags & EDGE_FALLTHRU) | |
| 1942 && n_basic_blocks > NUM_FIXED_BLOCKS + 1) | |
| 1943 { | |
| 1944 if (dump_file) | |
| 1945 fprintf (dump_file, | |
| 1946 "Deleting fallthru block %i.\n", | |
| 1947 b->index); | |
| 1948 | |
| 1949 c = b->prev_bb == ENTRY_BLOCK_PTR ? b->next_bb : b->prev_bb; | |
| 1950 redirect_edge_succ_nodup (single_pred_edge (b), | |
| 1951 single_succ (b)); | |
| 1952 delete_basic_block (b); | |
| 1953 changed = true; | |
| 1954 b = c; | |
|
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1955 continue; |
| 0 | 1956 } |
| 1957 | |
| 1958 if (single_succ_p (b) | |
| 1959 && (s = single_succ_edge (b)) | |
| 1960 && !(s->flags & EDGE_COMPLEX) | |
| 1961 && (c = s->dest) != EXIT_BLOCK_PTR | |
| 1962 && single_pred_p (c) | |
| 1963 && b != c) | |
| 1964 { | |
| 1965 /* When not in cfg_layout mode use code aware of reordering | |
| 1966 INSN. This code possibly creates new basic blocks so it | |
| 1967 does not fit merge_blocks interface and is kept here in | |
| 1968 hope that it will become useless once more of compiler | |
| 1969 is transformed to use cfg_layout mode. */ | |
| 1970 | |
| 1971 if ((mode & CLEANUP_CFGLAYOUT) | |
| 1972 && can_merge_blocks_p (b, c)) | |
| 1973 { | |
| 1974 merge_blocks (b, c); | |
| 1975 update_forwarder_flag (b); | |
| 1976 changed_here = true; | |
| 1977 } | |
| 1978 else if (!(mode & CLEANUP_CFGLAYOUT) | |
| 1979 /* If the jump insn has side effects, | |
| 1980 we can't kill the edge. */ | |
| 1981 && (!JUMP_P (BB_END (b)) | |
| 1982 || (reload_completed | |
| 1983 ? simplejump_p (BB_END (b)) | |
| 1984 : (onlyjump_p (BB_END (b)) | |
| 1985 && !tablejump_p (BB_END (b), | |
| 1986 NULL, NULL)))) | |
| 1987 && (next = merge_blocks_move (s, b, c, mode))) | |
| 1988 { | |
| 1989 b = next; | |
| 1990 changed_here = true; | |
| 1991 } | |
| 1992 } | |
| 1993 | |
| 1994 /* Simplify branch over branch. */ | |
| 1995 if ((mode & CLEANUP_EXPENSIVE) | |
| 1996 && !(mode & CLEANUP_CFGLAYOUT) | |
| 1997 && try_simplify_condjump (b)) | |
| 1998 changed_here = true; | |
| 1999 | |
| 2000 /* If B has a single outgoing edge, but uses a | |
| 2001 non-trivial jump instruction without side-effects, we | |
| 2002 can either delete the jump entirely, or replace it | |
| 2003 with a simple unconditional jump. */ | |
| 2004 if (single_succ_p (b) | |
| 2005 && single_succ (b) != EXIT_BLOCK_PTR | |
| 2006 && onlyjump_p (BB_END (b)) | |
| 2007 && !find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX) | |
| 2008 && try_redirect_by_replacing_jump (single_succ_edge (b), | |
| 2009 single_succ (b), | |
| 2010 (mode & CLEANUP_CFGLAYOUT) != 0)) | |
| 2011 { | |
| 2012 update_forwarder_flag (b); | |
| 2013 changed_here = true; | |
| 2014 } | |
| 2015 | |
| 2016 /* Simplify branch to branch. */ | |
| 2017 if (try_forward_edges (mode, b)) | |
| 2018 changed_here = true; | |
| 2019 | |
| 2020 /* Look for shared code between blocks. */ | |
| 2021 if ((mode & CLEANUP_CROSSJUMP) | |
| 2022 && try_crossjump_bb (mode, b)) | |
| 2023 changed_here = true; | |
| 2024 | |
| 2025 /* Don't get confused by the index shift caused by | |
| 2026 deleting blocks. */ | |
| 2027 if (!changed_here) | |
| 2028 b = b->next_bb; | |
| 2029 else | |
| 2030 changed = true; | |
| 2031 } | |
| 2032 | |
| 2033 if ((mode & CLEANUP_CROSSJUMP) | |
| 2034 && try_crossjump_bb (mode, EXIT_BLOCK_PTR)) | |
| 2035 changed = true; | |
| 2036 | |
| 2037 #ifdef ENABLE_CHECKING | |
| 2038 if (changed) | |
| 2039 verify_flow_info (); | |
| 2040 #endif | |
| 2041 | |
| 2042 changed_overall |= changed; | |
| 2043 first_pass = false; | |
| 2044 } | |
| 2045 while (changed); | |
| 2046 } | |
| 2047 | |
| 2048 FOR_ALL_BB (b) | |
| 2049 b->flags &= ~(BB_FORWARDER_BLOCK | BB_NONTHREADABLE_BLOCK); | |
| 2050 | |
| 2051 return changed_overall; | |
| 2052 } | |
| 2053 | |
| 2054 /* Delete all unreachable basic blocks. */ | |
| 2055 | |
| 2056 bool | |
| 2057 delete_unreachable_blocks (void) | |
| 2058 { | |
| 2059 bool changed = false; | |
|
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2060 basic_block b, prev_bb; |
| 0 | 2061 |
| 2062 find_unreachable_blocks (); | |
| 2063 | |
|
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2064 /* When we're in GIMPLE mode and there may be debug insns, we should |
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2065 delete blocks in reverse dominator order, so as to get a chance |
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2066 to substitute all released DEFs into debug stmts. If we don't |
|
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2067 have dominators information, walking blocks backward gets us a |
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2068 better chance of retaining most debug information than |
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2069 otherwise. */ |
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2070 if (MAY_HAVE_DEBUG_STMTS && current_ir_type () == IR_GIMPLE |
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2071 && dom_info_available_p (CDI_DOMINATORS)) |
| 0 | 2072 { |
|
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2073 for (b = EXIT_BLOCK_PTR->prev_bb; b != ENTRY_BLOCK_PTR; b = prev_bb) |
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2074 { |
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2075 prev_bb = b->prev_bb; |
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2076 |
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2077 if (!(b->flags & BB_REACHABLE)) |
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2078 { |
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2079 /* Speed up the removal of blocks that don't dominate |
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2080 others. Walking backwards, this should be the common |
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2081 case. */ |
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2082 if (!first_dom_son (CDI_DOMINATORS, b)) |
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2083 delete_basic_block (b); |
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2084 else |
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2085 { |
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2086 VEC (basic_block, heap) *h |
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2087 = get_all_dominated_blocks (CDI_DOMINATORS, b); |
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2088 |
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2089 while (VEC_length (basic_block, h)) |
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2090 { |
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2091 b = VEC_pop (basic_block, h); |
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2092 |
|
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2093 prev_bb = b->prev_bb; |
| 0 | 2094 |
|
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2095 gcc_assert (!(b->flags & BB_REACHABLE)); |
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2096 |
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2097 delete_basic_block (b); |
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2098 } |
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2099 |
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2100 VEC_free (basic_block, heap, h); |
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2101 } |
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2102 |
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2103 changed = true; |
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2104 } |
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2105 } |
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2106 } |
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2107 else |
|
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2108 { |
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|
2109 for (b = EXIT_BLOCK_PTR->prev_bb; b != ENTRY_BLOCK_PTR; b = prev_bb) |
| 0 | 2110 { |
|
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2111 prev_bb = b->prev_bb; |
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2112 |
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2113 if (!(b->flags & BB_REACHABLE)) |
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2114 { |
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2115 delete_basic_block (b); |
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2116 changed = true; |
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2117 } |
| 0 | 2118 } |
| 2119 } | |
| 2120 | |
| 2121 if (changed) | |
| 2122 tidy_fallthru_edges (); | |
| 2123 return changed; | |
| 2124 } | |
| 2125 | |
| 2126 /* Delete any jump tables never referenced. We can't delete them at the | |
| 2127 time of removing tablejump insn as they are referenced by the preceding | |
| 2128 insns computing the destination, so we delay deleting and garbagecollect | |
| 2129 them once life information is computed. */ | |
| 2130 void | |
| 2131 delete_dead_jumptables (void) | |
| 2132 { | |
| 2133 basic_block bb; | |
| 2134 | |
| 2135 /* A dead jump table does not belong to any basic block. Scan insns | |
| 2136 between two adjacent basic blocks. */ | |
| 2137 FOR_EACH_BB (bb) | |
| 2138 { | |
| 2139 rtx insn, next; | |
| 2140 | |
| 2141 for (insn = NEXT_INSN (BB_END (bb)); | |
| 2142 insn && !NOTE_INSN_BASIC_BLOCK_P (insn); | |
| 2143 insn = next) | |
| 2144 { | |
| 2145 next = NEXT_INSN (insn); | |
| 2146 if (LABEL_P (insn) | |
| 2147 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn) | |
|
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2148 && JUMP_TABLE_DATA_P (next)) |
| 0 | 2149 { |
| 2150 rtx label = insn, jump = next; | |
| 2151 | |
| 2152 if (dump_file) | |
| 2153 fprintf (dump_file, "Dead jumptable %i removed\n", | |
| 2154 INSN_UID (insn)); | |
| 2155 | |
| 2156 next = NEXT_INSN (next); | |
| 2157 delete_insn (jump); | |
| 2158 delete_insn (label); | |
| 2159 } | |
| 2160 } | |
| 2161 } | |
| 2162 } | |
| 2163 | |
| 2164 | |
| 2165 /* Tidy the CFG by deleting unreachable code and whatnot. */ | |
| 2166 | |
| 2167 bool | |
| 2168 cleanup_cfg (int mode) | |
| 2169 { | |
| 2170 bool changed = false; | |
| 2171 | |
| 2172 /* Set the cfglayout mode flag here. We could update all the callers | |
| 2173 but that is just inconvenient, especially given that we eventually | |
| 2174 want to have cfglayout mode as the default. */ | |
| 2175 if (current_ir_type () == IR_RTL_CFGLAYOUT) | |
| 2176 mode |= CLEANUP_CFGLAYOUT; | |
| 2177 | |
| 2178 timevar_push (TV_CLEANUP_CFG); | |
| 2179 if (delete_unreachable_blocks ()) | |
| 2180 { | |
| 2181 changed = true; | |
| 2182 /* We've possibly created trivially dead code. Cleanup it right | |
| 2183 now to introduce more opportunities for try_optimize_cfg. */ | |
| 2184 if (!(mode & (CLEANUP_NO_INSN_DEL)) | |
| 2185 && !reload_completed) | |
| 2186 delete_trivially_dead_insns (get_insns (), max_reg_num ()); | |
| 2187 } | |
| 2188 | |
| 2189 compact_blocks (); | |
| 2190 | |
| 2191 /* To tail-merge blocks ending in the same noreturn function (e.g. | |
| 2192 a call to abort) we have to insert fake edges to exit. Do this | |
| 2193 here once. The fake edges do not interfere with any other CFG | |
| 2194 cleanups. */ | |
| 2195 if (mode & CLEANUP_CROSSJUMP) | |
| 2196 add_noreturn_fake_exit_edges (); | |
| 2197 | |
| 2198 if (!dbg_cnt (cfg_cleanup)) | |
| 2199 return changed; | |
| 2200 | |
| 2201 while (try_optimize_cfg (mode)) | |
| 2202 { | |
| 2203 delete_unreachable_blocks (), changed = true; | |
| 2204 if (!(mode & CLEANUP_NO_INSN_DEL)) | |
| 2205 { | |
| 2206 /* Try to remove some trivially dead insns when doing an expensive | |
| 2207 cleanup. But delete_trivially_dead_insns doesn't work after | |
| 2208 reload (it only handles pseudos) and run_fast_dce is too costly | |
| 2209 to run in every iteration. | |
| 2210 | |
| 2211 For effective cross jumping, we really want to run a fast DCE to | |
| 2212 clean up any dead conditions, or they get in the way of performing | |
| 2213 useful tail merges. | |
| 2214 | |
| 2215 Other transformations in cleanup_cfg are not so sensitive to dead | |
| 2216 code, so delete_trivially_dead_insns or even doing nothing at all | |
| 2217 is good enough. */ | |
| 2218 if ((mode & CLEANUP_EXPENSIVE) && !reload_completed | |
| 2219 && !delete_trivially_dead_insns (get_insns (), max_reg_num ())) | |
| 2220 break; | |
| 2221 else if ((mode & CLEANUP_CROSSJUMP) | |
| 2222 && crossjumps_occured) | |
| 2223 run_fast_dce (); | |
| 2224 } | |
| 2225 else | |
| 2226 break; | |
| 2227 } | |
| 2228 | |
| 2229 if (mode & CLEANUP_CROSSJUMP) | |
| 2230 remove_fake_exit_edges (); | |
| 2231 | |
| 2232 /* Don't call delete_dead_jumptables in cfglayout mode, because | |
| 2233 that function assumes that jump tables are in the insns stream. | |
| 2234 But we also don't _have_ to delete dead jumptables in cfglayout | |
| 2235 mode because we shouldn't even be looking at things that are | |
| 2236 not in a basic block. Dead jumptables are cleaned up when | |
| 2237 going out of cfglayout mode. */ | |
| 2238 if (!(mode & CLEANUP_CFGLAYOUT)) | |
| 2239 delete_dead_jumptables (); | |
| 2240 | |
| 2241 timevar_pop (TV_CLEANUP_CFG); | |
| 2242 | |
| 2243 return changed; | |
| 2244 } | |
| 2245 | |
| 2246 static unsigned int | |
| 2247 rest_of_handle_jump (void) | |
| 2248 { | |
| 2249 if (crtl->tail_call_emit) | |
| 2250 fixup_tail_calls (); | |
| 2251 return 0; | |
| 2252 } | |
| 2253 | |
| 2254 struct rtl_opt_pass pass_jump = | |
| 2255 { | |
| 2256 { | |
| 2257 RTL_PASS, | |
| 2258 "sibling", /* name */ | |
| 2259 NULL, /* gate */ | |
| 2260 rest_of_handle_jump, /* execute */ | |
| 2261 NULL, /* sub */ | |
| 2262 NULL, /* next */ | |
| 2263 0, /* static_pass_number */ | |
| 2264 TV_JUMP, /* tv_id */ | |
| 2265 0, /* properties_required */ | |
| 2266 0, /* properties_provided */ | |
| 2267 0, /* properties_destroyed */ | |
| 2268 TODO_ggc_collect, /* todo_flags_start */ | |
| 2269 TODO_verify_flow, /* todo_flags_finish */ | |
| 2270 } | |
| 2271 }; | |
| 2272 | |
| 2273 | |
| 2274 static unsigned int | |
| 2275 rest_of_handle_jump2 (void) | |
| 2276 { | |
| 2277 delete_trivially_dead_insns (get_insns (), max_reg_num ()); | |
| 2278 if (dump_file) | |
| 2279 dump_flow_info (dump_file, dump_flags); | |
| 2280 cleanup_cfg ((optimize ? CLEANUP_EXPENSIVE : 0) | |
| 2281 | (flag_thread_jumps ? CLEANUP_THREADING : 0)); | |
| 2282 return 0; | |
| 2283 } | |
| 2284 | |
| 2285 | |
| 2286 struct rtl_opt_pass pass_jump2 = | |
| 2287 { | |
| 2288 { | |
| 2289 RTL_PASS, | |
| 2290 "jump", /* name */ | |
| 2291 NULL, /* gate */ | |
| 2292 rest_of_handle_jump2, /* execute */ | |
| 2293 NULL, /* sub */ | |
| 2294 NULL, /* next */ | |
| 2295 0, /* static_pass_number */ | |
| 2296 TV_JUMP, /* tv_id */ | |
| 2297 0, /* properties_required */ | |
| 2298 0, /* properties_provided */ | |
| 2299 0, /* properties_destroyed */ | |
| 2300 TODO_ggc_collect, /* todo_flags_start */ | |
| 2301 TODO_dump_func | TODO_verify_rtl_sharing,/* todo_flags_finish */ | |
| 2302 } | |
| 2303 }; | |
| 2304 | |
| 2305 |