Mercurial > hg > CbC > CbC_gcc
annotate gcc/cfgcleanup.c @ 63:b7f97abdc517 gcc-4.6-20100522
update gcc from gcc-4.5.0 to gcc-4.6
| author | ryoma <e075725@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Mon, 24 May 2010 12:47:05 +0900 |
| parents | 77e2b8dfacca |
| children | f6334be47118 |
| rev | line source |
|---|---|
| 0 | 1 /* Control flow optimization code for GNU compiler. |
| 2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, | |
|
63
b7f97abdc517
update gcc from gcc-4.5.0 to gcc-4.6
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
55
diff
changeset
|
3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2010 |
| 0 | 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 bool old_insns_match_p (int, rtx, rtx); | |
| 72 | |
| 73 static void merge_blocks_move_predecessor_nojumps (basic_block, basic_block); | |
| 74 static void merge_blocks_move_successor_nojumps (basic_block, basic_block); | |
| 75 static bool try_optimize_cfg (int); | |
| 76 static bool try_simplify_condjump (basic_block); | |
| 77 static bool try_forward_edges (int, basic_block); | |
| 78 static edge thread_jump (edge, basic_block); | |
| 79 static bool mark_effect (rtx, bitmap); | |
| 80 static void notice_new_block (basic_block); | |
| 81 static void update_forwarder_flag (basic_block); | |
| 82 static int mentions_nonequal_regs (rtx *, void *); | |
| 83 static void merge_memattrs (rtx, rtx); | |
| 84 | |
| 85 /* Set flags for newly created block. */ | |
| 86 | |
| 87 static void | |
| 88 notice_new_block (basic_block bb) | |
| 89 { | |
| 90 if (!bb) | |
| 91 return; | |
| 92 | |
| 93 if (forwarder_block_p (bb)) | |
| 94 bb->flags |= BB_FORWARDER_BLOCK; | |
| 95 } | |
| 96 | |
| 97 /* Recompute forwarder flag after block has been modified. */ | |
| 98 | |
| 99 static void | |
| 100 update_forwarder_flag (basic_block bb) | |
| 101 { | |
| 102 if (forwarder_block_p (bb)) | |
| 103 bb->flags |= BB_FORWARDER_BLOCK; | |
| 104 else | |
| 105 bb->flags &= ~BB_FORWARDER_BLOCK; | |
| 106 } | |
| 107 | |
| 108 /* Simplify a conditional jump around an unconditional jump. | |
| 109 Return true if something changed. */ | |
| 110 | |
| 111 static bool | |
| 112 try_simplify_condjump (basic_block cbranch_block) | |
| 113 { | |
| 114 basic_block jump_block, jump_dest_block, cbranch_dest_block; | |
| 115 edge cbranch_jump_edge, cbranch_fallthru_edge; | |
| 116 rtx cbranch_insn; | |
| 117 | |
| 118 /* Verify that there are exactly two successors. */ | |
| 119 if (EDGE_COUNT (cbranch_block->succs) != 2) | |
| 120 return false; | |
| 121 | |
| 122 /* Verify that we've got a normal conditional branch at the end | |
| 123 of the block. */ | |
| 124 cbranch_insn = BB_END (cbranch_block); | |
| 125 if (!any_condjump_p (cbranch_insn)) | |
| 126 return false; | |
| 127 | |
| 128 cbranch_fallthru_edge = FALLTHRU_EDGE (cbranch_block); | |
| 129 cbranch_jump_edge = BRANCH_EDGE (cbranch_block); | |
| 130 | |
| 131 /* The next block must not have multiple predecessors, must not | |
| 132 be the last block in the function, and must contain just the | |
| 133 unconditional jump. */ | |
| 134 jump_block = cbranch_fallthru_edge->dest; | |
| 135 if (!single_pred_p (jump_block) | |
| 136 || jump_block->next_bb == EXIT_BLOCK_PTR | |
| 137 || !FORWARDER_BLOCK_P (jump_block)) | |
| 138 return false; | |
| 139 jump_dest_block = single_succ (jump_block); | |
| 140 | |
| 141 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 142 mess up unconditional or indirect jumps that cross between hot | |
| 143 and cold sections. | |
| 144 | |
| 145 Basic block partitioning may result in some jumps that appear to | |
| 146 be optimizable (or blocks that appear to be mergeable), but which really | |
| 147 must be left untouched (they are required to make it safely across | |
| 148 partition boundaries). See the comments at the top of | |
| 149 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 150 | |
| 151 if (BB_PARTITION (jump_block) != BB_PARTITION (jump_dest_block) | |
| 152 || (cbranch_jump_edge->flags & EDGE_CROSSING)) | |
| 153 return false; | |
| 154 | |
| 155 /* The conditional branch must target the block after the | |
| 156 unconditional branch. */ | |
| 157 cbranch_dest_block = cbranch_jump_edge->dest; | |
| 158 | |
| 159 if (cbranch_dest_block == EXIT_BLOCK_PTR | |
| 160 || !can_fallthru (jump_block, cbranch_dest_block)) | |
| 161 return false; | |
| 162 | |
| 163 /* Invert the conditional branch. */ | |
| 164 if (!invert_jump (cbranch_insn, block_label (jump_dest_block), 0)) | |
| 165 return false; | |
| 166 | |
| 167 if (dump_file) | |
| 168 fprintf (dump_file, "Simplifying condjump %i around jump %i\n", | |
| 169 INSN_UID (cbranch_insn), INSN_UID (BB_END (jump_block))); | |
| 170 | |
| 171 /* Success. Update the CFG to match. Note that after this point | |
| 172 the edge variable names appear backwards; the redirection is done | |
| 173 this way to preserve edge profile data. */ | |
| 174 cbranch_jump_edge = redirect_edge_succ_nodup (cbranch_jump_edge, | |
| 175 cbranch_dest_block); | |
| 176 cbranch_fallthru_edge = redirect_edge_succ_nodup (cbranch_fallthru_edge, | |
| 177 jump_dest_block); | |
| 178 cbranch_jump_edge->flags |= EDGE_FALLTHRU; | |
| 179 cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU; | |
| 180 update_br_prob_note (cbranch_block); | |
| 181 | |
| 182 /* Delete the block with the unconditional jump, and clean up the mess. */ | |
| 183 delete_basic_block (jump_block); | |
| 184 tidy_fallthru_edge (cbranch_jump_edge); | |
| 185 update_forwarder_flag (cbranch_block); | |
| 186 | |
| 187 return true; | |
| 188 } | |
| 189 | |
| 190 /* Attempt to prove that operation is NOOP using CSElib or mark the effect | |
| 191 on register. Used by jump threading. */ | |
| 192 | |
| 193 static bool | |
| 194 mark_effect (rtx exp, regset nonequal) | |
| 195 { | |
| 196 int regno; | |
| 197 rtx dest; | |
| 198 switch (GET_CODE (exp)) | |
| 199 { | |
| 200 /* In case we do clobber the register, mark it as equal, as we know the | |
| 201 value is dead so it don't have to match. */ | |
| 202 case CLOBBER: | |
| 203 if (REG_P (XEXP (exp, 0))) | |
| 204 { | |
| 205 dest = XEXP (exp, 0); | |
| 206 regno = REGNO (dest); | |
| 207 CLEAR_REGNO_REG_SET (nonequal, regno); | |
| 208 if (regno < FIRST_PSEUDO_REGISTER) | |
| 209 { | |
| 210 int n = hard_regno_nregs[regno][GET_MODE (dest)]; | |
| 211 while (--n > 0) | |
| 212 CLEAR_REGNO_REG_SET (nonequal, regno + n); | |
| 213 } | |
| 214 } | |
| 215 return false; | |
| 216 | |
| 217 case SET: | |
| 218 if (rtx_equal_for_cselib_p (SET_DEST (exp), SET_SRC (exp))) | |
| 219 return false; | |
| 220 dest = SET_DEST (exp); | |
| 221 if (dest == pc_rtx) | |
| 222 return false; | |
| 223 if (!REG_P (dest)) | |
| 224 return true; | |
| 225 regno = REGNO (dest); | |
| 226 SET_REGNO_REG_SET (nonequal, regno); | |
| 227 if (regno < FIRST_PSEUDO_REGISTER) | |
| 228 { | |
| 229 int n = hard_regno_nregs[regno][GET_MODE (dest)]; | |
| 230 while (--n > 0) | |
| 231 SET_REGNO_REG_SET (nonequal, regno + n); | |
| 232 } | |
| 233 return false; | |
| 234 | |
| 235 default: | |
| 236 return false; | |
| 237 } | |
| 238 } | |
| 239 | |
| 240 /* Return nonzero if X is a register set in regset DATA. | |
| 241 Called via for_each_rtx. */ | |
| 242 static int | |
| 243 mentions_nonequal_regs (rtx *x, void *data) | |
| 244 { | |
| 245 regset nonequal = (regset) data; | |
| 246 if (REG_P (*x)) | |
| 247 { | |
| 248 int regno; | |
| 249 | |
| 250 regno = REGNO (*x); | |
| 251 if (REGNO_REG_SET_P (nonequal, regno)) | |
| 252 return 1; | |
| 253 if (regno < FIRST_PSEUDO_REGISTER) | |
| 254 { | |
| 255 int n = hard_regno_nregs[regno][GET_MODE (*x)]; | |
| 256 while (--n > 0) | |
| 257 if (REGNO_REG_SET_P (nonequal, regno + n)) | |
| 258 return 1; | |
| 259 } | |
| 260 } | |
| 261 return 0; | |
| 262 } | |
| 263 /* Attempt to prove that the basic block B will have no side effects and | |
| 264 always continues in the same edge if reached via E. Return the edge | |
| 265 if exist, NULL otherwise. */ | |
| 266 | |
| 267 static edge | |
| 268 thread_jump (edge e, basic_block b) | |
| 269 { | |
| 270 rtx set1, set2, cond1, cond2, insn; | |
| 271 enum rtx_code code1, code2, reversed_code2; | |
| 272 bool reverse1 = false; | |
| 273 unsigned i; | |
| 274 regset nonequal; | |
| 275 bool failed = false; | |
| 276 reg_set_iterator rsi; | |
| 277 | |
| 278 if (b->flags & BB_NONTHREADABLE_BLOCK) | |
| 279 return NULL; | |
| 280 | |
| 281 /* At the moment, we do handle only conditional jumps, but later we may | |
| 282 want to extend this code to tablejumps and others. */ | |
| 283 if (EDGE_COUNT (e->src->succs) != 2) | |
| 284 return NULL; | |
| 285 if (EDGE_COUNT (b->succs) != 2) | |
| 286 { | |
| 287 b->flags |= BB_NONTHREADABLE_BLOCK; | |
| 288 return NULL; | |
| 289 } | |
| 290 | |
| 291 /* Second branch must end with onlyjump, as we will eliminate the jump. */ | |
| 292 if (!any_condjump_p (BB_END (e->src))) | |
| 293 return NULL; | |
| 294 | |
| 295 if (!any_condjump_p (BB_END (b)) || !onlyjump_p (BB_END (b))) | |
| 296 { | |
| 297 b->flags |= BB_NONTHREADABLE_BLOCK; | |
| 298 return NULL; | |
| 299 } | |
| 300 | |
| 301 set1 = pc_set (BB_END (e->src)); | |
| 302 set2 = pc_set (BB_END (b)); | |
| 303 if (((e->flags & EDGE_FALLTHRU) != 0) | |
| 304 != (XEXP (SET_SRC (set1), 1) == pc_rtx)) | |
| 305 reverse1 = true; | |
| 306 | |
| 307 cond1 = XEXP (SET_SRC (set1), 0); | |
| 308 cond2 = XEXP (SET_SRC (set2), 0); | |
| 309 if (reverse1) | |
| 310 code1 = reversed_comparison_code (cond1, BB_END (e->src)); | |
| 311 else | |
| 312 code1 = GET_CODE (cond1); | |
| 313 | |
| 314 code2 = GET_CODE (cond2); | |
| 315 reversed_code2 = reversed_comparison_code (cond2, BB_END (b)); | |
| 316 | |
| 317 if (!comparison_dominates_p (code1, code2) | |
| 318 && !comparison_dominates_p (code1, reversed_code2)) | |
| 319 return NULL; | |
| 320 | |
| 321 /* Ensure that the comparison operators are equivalent. | |
| 322 ??? This is far too pessimistic. We should allow swapped operands, | |
| 323 different CCmodes, or for example comparisons for interval, that | |
| 324 dominate even when operands are not equivalent. */ | |
| 325 if (!rtx_equal_p (XEXP (cond1, 0), XEXP (cond2, 0)) | |
| 326 || !rtx_equal_p (XEXP (cond1, 1), XEXP (cond2, 1))) | |
| 327 return NULL; | |
| 328 | |
| 329 /* Short circuit cases where block B contains some side effects, as we can't | |
| 330 safely bypass it. */ | |
| 331 for (insn = NEXT_INSN (BB_HEAD (b)); insn != NEXT_INSN (BB_END (b)); | |
| 332 insn = NEXT_INSN (insn)) | |
| 333 if (INSN_P (insn) && side_effects_p (PATTERN (insn))) | |
| 334 { | |
| 335 b->flags |= BB_NONTHREADABLE_BLOCK; | |
| 336 return NULL; | |
| 337 } | |
| 338 | |
|
63
b7f97abdc517
update gcc from gcc-4.5.0 to gcc-4.6
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
55
diff
changeset
|
339 cselib_init (0); |
| 0 | 340 |
| 341 /* First process all values computed in the source basic block. */ | |
| 342 for (insn = NEXT_INSN (BB_HEAD (e->src)); | |
| 343 insn != NEXT_INSN (BB_END (e->src)); | |
| 344 insn = NEXT_INSN (insn)) | |
| 345 if (INSN_P (insn)) | |
| 346 cselib_process_insn (insn); | |
| 347 | |
| 348 nonequal = BITMAP_ALLOC (NULL); | |
| 349 CLEAR_REG_SET (nonequal); | |
| 350 | |
| 351 /* Now assume that we've continued by the edge E to B and continue | |
| 352 processing as if it were same basic block. | |
| 353 Our goal is to prove that whole block is an NOOP. */ | |
| 354 | |
| 355 for (insn = NEXT_INSN (BB_HEAD (b)); | |
| 356 insn != NEXT_INSN (BB_END (b)) && !failed; | |
| 357 insn = NEXT_INSN (insn)) | |
| 358 { | |
| 359 if (INSN_P (insn)) | |
| 360 { | |
| 361 rtx pat = PATTERN (insn); | |
| 362 | |
| 363 if (GET_CODE (pat) == PARALLEL) | |
| 364 { | |
| 365 for (i = 0; i < (unsigned)XVECLEN (pat, 0); i++) | |
| 366 failed |= mark_effect (XVECEXP (pat, 0, i), nonequal); | |
| 367 } | |
| 368 else | |
| 369 failed |= mark_effect (pat, nonequal); | |
| 370 } | |
| 371 | |
| 372 cselib_process_insn (insn); | |
| 373 } | |
| 374 | |
| 375 /* Later we should clear nonequal of dead registers. So far we don't | |
| 376 have life information in cfg_cleanup. */ | |
| 377 if (failed) | |
| 378 { | |
| 379 b->flags |= BB_NONTHREADABLE_BLOCK; | |
| 380 goto failed_exit; | |
| 381 } | |
| 382 | |
| 383 /* cond2 must not mention any register that is not equal to the | |
| 384 former block. */ | |
| 385 if (for_each_rtx (&cond2, mentions_nonequal_regs, nonequal)) | |
| 386 goto failed_exit; | |
| 387 | |
| 388 EXECUTE_IF_SET_IN_REG_SET (nonequal, 0, i, rsi) | |
| 389 goto failed_exit; | |
| 390 | |
| 391 BITMAP_FREE (nonequal); | |
| 392 cselib_finish (); | |
| 393 if ((comparison_dominates_p (code1, code2) != 0) | |
| 394 != (XEXP (SET_SRC (set2), 1) == pc_rtx)) | |
| 395 return BRANCH_EDGE (b); | |
| 396 else | |
| 397 return FALLTHRU_EDGE (b); | |
| 398 | |
| 399 failed_exit: | |
| 400 BITMAP_FREE (nonequal); | |
| 401 cselib_finish (); | |
| 402 return NULL; | |
| 403 } | |
| 404 | |
| 405 /* Attempt to forward edges leaving basic block B. | |
| 406 Return true if successful. */ | |
| 407 | |
| 408 static bool | |
| 409 try_forward_edges (int mode, basic_block b) | |
| 410 { | |
| 411 bool changed = false; | |
| 412 edge_iterator ei; | |
| 413 edge e, *threaded_edges = NULL; | |
| 414 | |
| 415 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 416 mess up unconditional or indirect jumps that cross between hot | |
| 417 and cold sections. | |
| 418 | |
| 419 Basic block partitioning may result in some jumps that appear to | |
| 420 be optimizable (or blocks that appear to be mergeable), but which really | |
| 421 must be left untouched (they are required to make it safely across | |
| 422 partition boundaries). See the comments at the top of | |
| 423 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 424 | |
| 425 if (find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)) | |
| 426 return false; | |
| 427 | |
| 428 for (ei = ei_start (b->succs); (e = ei_safe_edge (ei)); ) | |
| 429 { | |
| 430 basic_block target, first; | |
| 431 int counter, goto_locus; | |
| 432 bool threaded = false; | |
| 433 int nthreaded_edges = 0; | |
| 434 bool may_thread = first_pass | df_get_bb_dirty (b); | |
| 435 | |
| 436 /* Skip complex edges because we don't know how to update them. | |
| 437 | |
| 438 Still handle fallthru edges, as we can succeed to forward fallthru | |
| 439 edge to the same place as the branch edge of conditional branch | |
| 440 and turn conditional branch to an unconditional branch. */ | |
| 441 if (e->flags & EDGE_COMPLEX) | |
| 442 { | |
| 443 ei_next (&ei); | |
| 444 continue; | |
| 445 } | |
| 446 | |
| 447 target = first = e->dest; | |
| 448 counter = NUM_FIXED_BLOCKS; | |
| 449 goto_locus = e->goto_locus; | |
| 450 | |
| 451 /* If we are partitioning hot/cold basic_blocks, we don't want to mess | |
| 452 up jumps that cross between hot/cold sections. | |
| 453 | |
| 454 Basic block partitioning may result in some jumps that appear | |
| 455 to be optimizable (or blocks that appear to be mergeable), but which | |
| 456 really must be left untouched (they are required to make it safely | |
| 457 across partition boundaries). See the comments at the top of | |
| 458 bb-reorder.c:partition_hot_cold_basic_blocks for complete | |
| 459 details. */ | |
| 460 | |
| 461 if (first != EXIT_BLOCK_PTR | |
| 462 && find_reg_note (BB_END (first), REG_CROSSING_JUMP, NULL_RTX)) | |
| 463 return false; | |
| 464 | |
| 465 while (counter < n_basic_blocks) | |
| 466 { | |
| 467 basic_block new_target = NULL; | |
| 468 bool new_target_threaded = false; | |
| 469 may_thread |= df_get_bb_dirty (target); | |
| 470 | |
| 471 if (FORWARDER_BLOCK_P (target) | |
| 472 && !(single_succ_edge (target)->flags & EDGE_CROSSING) | |
| 473 && single_succ (target) != EXIT_BLOCK_PTR) | |
| 474 { | |
| 475 /* Bypass trivial infinite loops. */ | |
| 476 new_target = single_succ (target); | |
| 477 if (target == new_target) | |
| 478 counter = n_basic_blocks; | |
| 479 else if (!optimize) | |
| 480 { | |
| 481 /* When not optimizing, ensure that edges or forwarder | |
| 482 blocks with different locus are not optimized out. */ | |
| 483 int locus = single_succ_edge (target)->goto_locus; | |
| 484 | |
| 485 if (locus && goto_locus && !locator_eq (locus, goto_locus)) | |
| 486 counter = n_basic_blocks; | |
| 487 else if (locus) | |
| 488 goto_locus = locus; | |
| 489 | |
| 490 if (INSN_P (BB_END (target))) | |
| 491 { | |
| 492 locus = INSN_LOCATOR (BB_END (target)); | |
| 493 | |
| 494 if (locus && goto_locus | |
| 495 && !locator_eq (locus, goto_locus)) | |
| 496 counter = n_basic_blocks; | |
| 497 else if (locus) | |
| 498 goto_locus = locus; | |
| 499 } | |
| 500 } | |
| 501 } | |
| 502 | |
| 503 /* Allow to thread only over one edge at time to simplify updating | |
| 504 of probabilities. */ | |
| 505 else if ((mode & CLEANUP_THREADING) && may_thread) | |
| 506 { | |
| 507 edge t = thread_jump (e, target); | |
| 508 if (t) | |
| 509 { | |
| 510 if (!threaded_edges) | |
| 511 threaded_edges = XNEWVEC (edge, n_basic_blocks); | |
| 512 else | |
| 513 { | |
| 514 int i; | |
| 515 | |
| 516 /* Detect an infinite loop across blocks not | |
| 517 including the start block. */ | |
| 518 for (i = 0; i < nthreaded_edges; ++i) | |
| 519 if (threaded_edges[i] == t) | |
| 520 break; | |
| 521 if (i < nthreaded_edges) | |
| 522 { | |
| 523 counter = n_basic_blocks; | |
| 524 break; | |
| 525 } | |
| 526 } | |
| 527 | |
| 528 /* Detect an infinite loop across the start block. */ | |
| 529 if (t->dest == b) | |
| 530 break; | |
| 531 | |
| 532 gcc_assert (nthreaded_edges < n_basic_blocks - NUM_FIXED_BLOCKS); | |
| 533 threaded_edges[nthreaded_edges++] = t; | |
| 534 | |
| 535 new_target = t->dest; | |
| 536 new_target_threaded = true; | |
| 537 } | |
| 538 } | |
| 539 | |
| 540 if (!new_target) | |
| 541 break; | |
| 542 | |
| 543 counter++; | |
| 544 target = new_target; | |
| 545 threaded |= new_target_threaded; | |
| 546 } | |
| 547 | |
| 548 if (counter >= n_basic_blocks) | |
| 549 { | |
| 550 if (dump_file) | |
| 551 fprintf (dump_file, "Infinite loop in BB %i.\n", | |
| 552 target->index); | |
| 553 } | |
| 554 else if (target == first) | |
| 555 ; /* We didn't do anything. */ | |
| 556 else | |
| 557 { | |
| 558 /* Save the values now, as the edge may get removed. */ | |
| 559 gcov_type edge_count = e->count; | |
| 560 int edge_probability = e->probability; | |
| 561 int edge_frequency; | |
| 562 int n = 0; | |
| 563 | |
| 564 e->goto_locus = goto_locus; | |
| 565 | |
| 566 /* Don't force if target is exit block. */ | |
| 567 if (threaded && target != EXIT_BLOCK_PTR) | |
| 568 { | |
| 569 notice_new_block (redirect_edge_and_branch_force (e, target)); | |
| 570 if (dump_file) | |
| 571 fprintf (dump_file, "Conditionals threaded.\n"); | |
| 572 } | |
| 573 else if (!redirect_edge_and_branch (e, target)) | |
| 574 { | |
| 575 if (dump_file) | |
| 576 fprintf (dump_file, | |
| 577 "Forwarding edge %i->%i to %i failed.\n", | |
| 578 b->index, e->dest->index, target->index); | |
| 579 ei_next (&ei); | |
| 580 continue; | |
| 581 } | |
| 582 | |
| 583 /* We successfully forwarded the edge. Now update profile | |
| 584 data: for each edge we traversed in the chain, remove | |
| 585 the original edge's execution count. */ | |
| 586 edge_frequency = ((edge_probability * b->frequency | |
| 587 + REG_BR_PROB_BASE / 2) | |
| 588 / REG_BR_PROB_BASE); | |
| 589 | |
| 590 if (!FORWARDER_BLOCK_P (b) && forwarder_block_p (b)) | |
| 591 b->flags |= BB_FORWARDER_BLOCK; | |
| 592 | |
| 593 do | |
| 594 { | |
| 595 edge t; | |
| 596 | |
| 597 if (!single_succ_p (first)) | |
| 598 { | |
| 599 gcc_assert (n < nthreaded_edges); | |
| 600 t = threaded_edges [n++]; | |
| 601 gcc_assert (t->src == first); | |
| 602 update_bb_profile_for_threading (first, edge_frequency, | |
| 603 edge_count, t); | |
| 604 update_br_prob_note (first); | |
| 605 } | |
| 606 else | |
| 607 { | |
| 608 first->count -= edge_count; | |
| 609 if (first->count < 0) | |
| 610 first->count = 0; | |
| 611 first->frequency -= edge_frequency; | |
| 612 if (first->frequency < 0) | |
| 613 first->frequency = 0; | |
| 614 /* It is possible that as the result of | |
| 615 threading we've removed edge as it is | |
| 616 threaded to the fallthru edge. Avoid | |
| 617 getting out of sync. */ | |
| 618 if (n < nthreaded_edges | |
| 619 && first == threaded_edges [n]->src) | |
| 620 n++; | |
| 621 t = single_succ_edge (first); | |
| 622 } | |
| 623 | |
| 624 t->count -= edge_count; | |
| 625 if (t->count < 0) | |
| 626 t->count = 0; | |
| 627 first = t->dest; | |
| 628 } | |
| 629 while (first != target); | |
| 630 | |
| 631 changed = true; | |
| 632 continue; | |
| 633 } | |
| 634 ei_next (&ei); | |
| 635 } | |
| 636 | |
| 637 if (threaded_edges) | |
| 638 free (threaded_edges); | |
| 639 return changed; | |
| 640 } | |
| 641 | |
| 642 | |
| 643 /* Blocks A and B are to be merged into a single block. A has no incoming | |
| 644 fallthru edge, so it can be moved before B without adding or modifying | |
| 645 any jumps (aside from the jump from A to B). */ | |
| 646 | |
| 647 static void | |
| 648 merge_blocks_move_predecessor_nojumps (basic_block a, basic_block b) | |
| 649 { | |
| 650 rtx barrier; | |
| 651 | |
| 652 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 653 mess up unconditional or indirect jumps that cross between hot | |
| 654 and cold sections. | |
| 655 | |
| 656 Basic block partitioning may result in some jumps that appear to | |
| 657 be optimizable (or blocks that appear to be mergeable), but which really | |
| 658 must be left untouched (they are required to make it safely across | |
| 659 partition boundaries). See the comments at the top of | |
| 660 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 661 | |
| 662 if (BB_PARTITION (a) != BB_PARTITION (b)) | |
| 663 return; | |
| 664 | |
| 665 barrier = next_nonnote_insn (BB_END (a)); | |
| 666 gcc_assert (BARRIER_P (barrier)); | |
| 667 delete_insn (barrier); | |
| 668 | |
| 669 /* Scramble the insn chain. */ | |
| 670 if (BB_END (a) != PREV_INSN (BB_HEAD (b))) | |
| 671 reorder_insns_nobb (BB_HEAD (a), BB_END (a), PREV_INSN (BB_HEAD (b))); | |
| 672 df_set_bb_dirty (a); | |
| 673 | |
| 674 if (dump_file) | |
| 675 fprintf (dump_file, "Moved block %d before %d and merged.\n", | |
| 676 a->index, b->index); | |
| 677 | |
| 678 /* Swap the records for the two blocks around. */ | |
| 679 | |
| 680 unlink_block (a); | |
| 681 link_block (a, b->prev_bb); | |
| 682 | |
| 683 /* Now blocks A and B are contiguous. Merge them. */ | |
| 684 merge_blocks (a, b); | |
| 685 } | |
| 686 | |
| 687 /* Blocks A and B are to be merged into a single block. B has no outgoing | |
| 688 fallthru edge, so it can be moved after A without adding or modifying | |
| 689 any jumps (aside from the jump from A to B). */ | |
| 690 | |
| 691 static void | |
| 692 merge_blocks_move_successor_nojumps (basic_block a, basic_block b) | |
| 693 { | |
| 694 rtx barrier, real_b_end; | |
| 695 rtx label, table; | |
| 696 | |
| 697 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 698 mess up unconditional or indirect jumps that cross between hot | |
| 699 and cold sections. | |
| 700 | |
| 701 Basic block partitioning may result in some jumps that appear to | |
| 702 be optimizable (or blocks that appear to be mergeable), but which really | |
| 703 must be left untouched (they are required to make it safely across | |
| 704 partition boundaries). See the comments at the top of | |
| 705 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 706 | |
| 707 if (BB_PARTITION (a) != BB_PARTITION (b)) | |
| 708 return; | |
| 709 | |
| 710 real_b_end = BB_END (b); | |
| 711 | |
| 712 /* If there is a jump table following block B temporarily add the jump table | |
| 713 to block B so that it will also be moved to the correct location. */ | |
| 714 if (tablejump_p (BB_END (b), &label, &table) | |
| 715 && prev_active_insn (label) == BB_END (b)) | |
| 716 { | |
| 717 BB_END (b) = table; | |
| 718 } | |
| 719 | |
| 720 /* There had better have been a barrier there. Delete it. */ | |
| 721 barrier = NEXT_INSN (BB_END (b)); | |
| 722 if (barrier && BARRIER_P (barrier)) | |
| 723 delete_insn (barrier); | |
| 724 | |
| 725 | |
| 726 /* Scramble the insn chain. */ | |
| 727 reorder_insns_nobb (BB_HEAD (b), BB_END (b), BB_END (a)); | |
| 728 | |
| 729 /* Restore the real end of b. */ | |
| 730 BB_END (b) = real_b_end; | |
| 731 | |
| 732 if (dump_file) | |
| 733 fprintf (dump_file, "Moved block %d after %d and merged.\n", | |
| 734 b->index, a->index); | |
| 735 | |
| 736 /* Now blocks A and B are contiguous. Merge them. */ | |
| 737 merge_blocks (a, b); | |
| 738 } | |
| 739 | |
| 740 /* Attempt to merge basic blocks that are potentially non-adjacent. | |
| 741 Return NULL iff the attempt failed, otherwise return basic block | |
| 742 where cleanup_cfg should continue. Because the merging commonly | |
| 743 moves basic block away or introduces another optimization | |
| 744 possibility, return basic block just before B so cleanup_cfg don't | |
| 745 need to iterate. | |
| 746 | |
| 747 It may be good idea to return basic block before C in the case | |
| 748 C has been moved after B and originally appeared earlier in the | |
| 749 insn sequence, but we have no information available about the | |
| 750 relative ordering of these two. Hopefully it is not too common. */ | |
| 751 | |
| 752 static basic_block | |
| 753 merge_blocks_move (edge e, basic_block b, basic_block c, int mode) | |
| 754 { | |
| 755 basic_block next; | |
| 756 | |
| 757 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 758 mess up unconditional or indirect jumps that cross between hot | |
| 759 and cold sections. | |
| 760 | |
| 761 Basic block partitioning may result in some jumps that appear to | |
| 762 be optimizable (or blocks that appear to be mergeable), but which really | |
| 763 must be left untouched (they are required to make it safely across | |
| 764 partition boundaries). See the comments at the top of | |
| 765 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 766 | |
| 767 if (BB_PARTITION (b) != BB_PARTITION (c)) | |
| 768 return NULL; | |
| 769 | |
| 770 /* If B has a fallthru edge to C, no need to move anything. */ | |
| 771 if (e->flags & EDGE_FALLTHRU) | |
| 772 { | |
| 773 int b_index = b->index, c_index = c->index; | |
| 774 merge_blocks (b, c); | |
| 775 update_forwarder_flag (b); | |
| 776 | |
| 777 if (dump_file) | |
| 778 fprintf (dump_file, "Merged %d and %d without moving.\n", | |
| 779 b_index, c_index); | |
| 780 | |
| 781 return b->prev_bb == ENTRY_BLOCK_PTR ? b : b->prev_bb; | |
| 782 } | |
| 783 | |
| 784 /* Otherwise we will need to move code around. Do that only if expensive | |
| 785 transformations are allowed. */ | |
| 786 else if (mode & CLEANUP_EXPENSIVE) | |
| 787 { | |
| 788 edge tmp_edge, b_fallthru_edge; | |
| 789 bool c_has_outgoing_fallthru; | |
| 790 bool b_has_incoming_fallthru; | |
| 791 edge_iterator ei; | |
| 792 | |
| 793 /* Avoid overactive code motion, as the forwarder blocks should be | |
| 794 eliminated by edge redirection instead. One exception might have | |
| 795 been if B is a forwarder block and C has no fallthru edge, but | |
| 796 that should be cleaned up by bb-reorder instead. */ | |
| 797 if (FORWARDER_BLOCK_P (b) || FORWARDER_BLOCK_P (c)) | |
| 798 return NULL; | |
| 799 | |
| 800 /* We must make sure to not munge nesting of lexical blocks, | |
| 801 and loop notes. This is done by squeezing out all the notes | |
| 802 and leaving them there to lie. Not ideal, but functional. */ | |
| 803 | |
| 804 FOR_EACH_EDGE (tmp_edge, ei, c->succs) | |
| 805 if (tmp_edge->flags & EDGE_FALLTHRU) | |
| 806 break; | |
| 807 | |
| 808 c_has_outgoing_fallthru = (tmp_edge != NULL); | |
| 809 | |
| 810 FOR_EACH_EDGE (tmp_edge, ei, b->preds) | |
| 811 if (tmp_edge->flags & EDGE_FALLTHRU) | |
| 812 break; | |
| 813 | |
| 814 b_has_incoming_fallthru = (tmp_edge != NULL); | |
| 815 b_fallthru_edge = tmp_edge; | |
| 816 next = b->prev_bb; | |
| 817 if (next == c) | |
| 818 next = next->prev_bb; | |
| 819 | |
| 820 /* Otherwise, we're going to try to move C after B. If C does | |
| 821 not have an outgoing fallthru, then it can be moved | |
| 822 immediately after B without introducing or modifying jumps. */ | |
| 823 if (! c_has_outgoing_fallthru) | |
| 824 { | |
| 825 merge_blocks_move_successor_nojumps (b, c); | |
| 826 return next == ENTRY_BLOCK_PTR ? next->next_bb : next; | |
| 827 } | |
| 828 | |
| 829 /* If B does not have an incoming fallthru, then it can be moved | |
| 830 immediately before C without introducing or modifying jumps. | |
| 831 C cannot be the first block, so we do not have to worry about | |
| 832 accessing a non-existent block. */ | |
| 833 | |
| 834 if (b_has_incoming_fallthru) | |
| 835 { | |
| 836 basic_block bb; | |
| 837 | |
| 838 if (b_fallthru_edge->src == ENTRY_BLOCK_PTR) | |
| 839 return NULL; | |
| 840 bb = force_nonfallthru (b_fallthru_edge); | |
| 841 if (bb) | |
| 842 notice_new_block (bb); | |
| 843 } | |
| 844 | |
| 845 merge_blocks_move_predecessor_nojumps (b, c); | |
| 846 return next == ENTRY_BLOCK_PTR ? next->next_bb : next; | |
| 847 } | |
| 848 | |
| 849 return NULL; | |
| 850 } | |
| 851 | |
| 852 | |
| 853 /* Removes the memory attributes of MEM expression | |
| 854 if they are not equal. */ | |
| 855 | |
| 856 void | |
| 857 merge_memattrs (rtx x, rtx y) | |
| 858 { | |
| 859 int i; | |
| 860 int j; | |
| 861 enum rtx_code code; | |
| 862 const char *fmt; | |
| 863 | |
| 864 if (x == y) | |
| 865 return; | |
| 866 if (x == 0 || y == 0) | |
| 867 return; | |
| 868 | |
| 869 code = GET_CODE (x); | |
| 870 | |
| 871 if (code != GET_CODE (y)) | |
| 872 return; | |
| 873 | |
| 874 if (GET_MODE (x) != GET_MODE (y)) | |
| 875 return; | |
| 876 | |
| 877 if (code == MEM && MEM_ATTRS (x) != MEM_ATTRS (y)) | |
| 878 { | |
| 879 if (! MEM_ATTRS (x)) | |
| 880 MEM_ATTRS (y) = 0; | |
| 881 else if (! MEM_ATTRS (y)) | |
| 882 MEM_ATTRS (x) = 0; | |
| 883 else | |
| 884 { | |
| 885 rtx mem_size; | |
| 886 | |
| 887 if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y)) | |
| 888 { | |
| 889 set_mem_alias_set (x, 0); | |
| 890 set_mem_alias_set (y, 0); | |
| 891 } | |
| 892 | |
| 893 if (! mem_expr_equal_p (MEM_EXPR (x), MEM_EXPR (y))) | |
| 894 { | |
| 895 set_mem_expr (x, 0); | |
| 896 set_mem_expr (y, 0); | |
| 897 set_mem_offset (x, 0); | |
| 898 set_mem_offset (y, 0); | |
| 899 } | |
| 900 else if (MEM_OFFSET (x) != MEM_OFFSET (y)) | |
| 901 { | |
| 902 set_mem_offset (x, 0); | |
| 903 set_mem_offset (y, 0); | |
| 904 } | |
| 905 | |
| 906 if (!MEM_SIZE (x)) | |
| 907 mem_size = NULL_RTX; | |
| 908 else if (!MEM_SIZE (y)) | |
| 909 mem_size = NULL_RTX; | |
| 910 else | |
| 911 mem_size = GEN_INT (MAX (INTVAL (MEM_SIZE (x)), | |
| 912 INTVAL (MEM_SIZE (y)))); | |
| 913 set_mem_size (x, mem_size); | |
| 914 set_mem_size (y, mem_size); | |
| 915 | |
| 916 set_mem_align (x, MIN (MEM_ALIGN (x), MEM_ALIGN (y))); | |
| 917 set_mem_align (y, MEM_ALIGN (x)); | |
| 918 } | |
| 919 } | |
| 920 | |
| 921 fmt = GET_RTX_FORMAT (code); | |
| 922 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
| 923 { | |
| 924 switch (fmt[i]) | |
| 925 { | |
| 926 case 'E': | |
| 927 /* Two vectors must have the same length. */ | |
| 928 if (XVECLEN (x, i) != XVECLEN (y, i)) | |
| 929 return; | |
| 930 | |
| 931 for (j = 0; j < XVECLEN (x, i); j++) | |
| 932 merge_memattrs (XVECEXP (x, i, j), XVECEXP (y, i, j)); | |
| 933 | |
| 934 break; | |
| 935 | |
| 936 case 'e': | |
| 937 merge_memattrs (XEXP (x, i), XEXP (y, i)); | |
| 938 } | |
| 939 } | |
| 940 return; | |
| 941 } | |
| 942 | |
| 943 | |
| 944 /* Return true if I1 and I2 are equivalent and thus can be crossjumped. */ | |
| 945 | |
| 946 static bool | |
| 947 old_insns_match_p (int mode ATTRIBUTE_UNUSED, rtx i1, rtx i2) | |
| 948 { | |
| 949 rtx p1, p2; | |
| 950 | |
| 951 /* Verify that I1 and I2 are equivalent. */ | |
| 952 if (GET_CODE (i1) != GET_CODE (i2)) | |
| 953 return false; | |
| 954 | |
|
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955 /* __builtin_unreachable() may lead to empty blocks (ending with |
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956 NOTE_INSN_BASIC_BLOCK). They may be crossjumped. */ |
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957 if (NOTE_INSN_BASIC_BLOCK_P (i1) && NOTE_INSN_BASIC_BLOCK_P (i2)) |
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958 return true; |
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959 |
| 0 | 960 p1 = PATTERN (i1); |
| 961 p2 = PATTERN (i2); | |
| 962 | |
| 963 if (GET_CODE (p1) != GET_CODE (p2)) | |
| 964 return false; | |
| 965 | |
| 966 /* If this is a CALL_INSN, compare register usage information. | |
| 967 If we don't check this on stack register machines, the two | |
| 968 CALL_INSNs might be merged leaving reg-stack.c with mismatching | |
| 969 numbers of stack registers in the same basic block. | |
| 970 If we don't check this on machines with delay slots, a delay slot may | |
| 971 be filled that clobbers a parameter expected by the subroutine. | |
| 972 | |
| 973 ??? We take the simple route for now and assume that if they're | |
|
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974 equal, they were constructed identically. |
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975 |
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976 Also check for identical exception regions. */ |
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977 |
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978 if (CALL_P (i1)) |
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979 { |
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980 /* Ensure the same EH region. */ |
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981 rtx n1 = find_reg_note (i1, REG_EH_REGION, 0); |
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982 rtx n2 = find_reg_note (i2, REG_EH_REGION, 0); |
| 0 | 983 |
|
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984 if (!n1 && n2) |
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985 return false; |
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986 |
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987 if (n1 && (!n2 || XEXP (n1, 0) != XEXP (n2, 0))) |
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988 return false; |
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989 |
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990 if (!rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1), |
| 0 | 991 CALL_INSN_FUNCTION_USAGE (i2)) |
|
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992 || SIBLING_CALL_P (i1) != SIBLING_CALL_P (i2)) |
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993 return false; |
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994 } |
| 0 | 995 |
| 996 #ifdef STACK_REGS | |
| 997 /* If cross_jump_death_matters is not 0, the insn's mode | |
| 998 indicates whether or not the insn contains any stack-like | |
| 999 regs. */ | |
| 1000 | |
| 1001 if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1)) | |
| 1002 { | |
| 1003 /* If register stack conversion has already been done, then | |
| 1004 death notes must also be compared before it is certain that | |
| 1005 the two instruction streams match. */ | |
| 1006 | |
| 1007 rtx note; | |
| 1008 HARD_REG_SET i1_regset, i2_regset; | |
| 1009 | |
| 1010 CLEAR_HARD_REG_SET (i1_regset); | |
| 1011 CLEAR_HARD_REG_SET (i2_regset); | |
| 1012 | |
| 1013 for (note = REG_NOTES (i1); note; note = XEXP (note, 1)) | |
| 1014 if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) | |
| 1015 SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0))); | |
| 1016 | |
| 1017 for (note = REG_NOTES (i2); note; note = XEXP (note, 1)) | |
| 1018 if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) | |
| 1019 SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0))); | |
| 1020 | |
| 1021 if (!hard_reg_set_equal_p (i1_regset, i2_regset)) | |
| 1022 return false; | |
| 1023 } | |
| 1024 #endif | |
| 1025 | |
| 1026 if (reload_completed | |
| 1027 ? rtx_renumbered_equal_p (p1, p2) : rtx_equal_p (p1, p2)) | |
| 1028 return true; | |
| 1029 | |
| 1030 return false; | |
| 1031 } | |
| 1032 | |
|
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1033 /* When comparing insns I1 and I2 in flow_find_cross_jump or |
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1034 flow_find_head_matching_sequence, ensure the notes match. */ |
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1035 |
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1036 static void |
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1037 merge_notes (rtx i1, rtx i2) |
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1038 { |
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1039 /* If the merged insns have different REG_EQUAL notes, then |
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1040 remove them. */ |
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1041 rtx equiv1 = find_reg_equal_equiv_note (i1); |
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1042 rtx equiv2 = find_reg_equal_equiv_note (i2); |
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1043 |
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1044 if (equiv1 && !equiv2) |
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1045 remove_note (i1, equiv1); |
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1046 else if (!equiv1 && equiv2) |
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1047 remove_note (i2, equiv2); |
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1048 else if (equiv1 && equiv2 |
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1049 && !rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0))) |
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1050 { |
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1051 remove_note (i1, equiv1); |
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1052 remove_note (i2, equiv2); |
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1053 } |
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1054 } |
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1055 |
| 0 | 1056 /* Look through the insns at the end of BB1 and BB2 and find the longest |
| 1057 sequence that are equivalent. Store the first insns for that sequence | |
| 1058 in *F1 and *F2 and return the sequence length. | |
| 1059 | |
| 1060 To simplify callers of this function, if the blocks match exactly, | |
| 1061 store the head of the blocks in *F1 and *F2. */ | |
| 1062 | |
|
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1063 int |
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1064 flow_find_cross_jump (basic_block bb1, basic_block bb2, rtx *f1, rtx *f2) |
| 0 | 1065 { |
| 1066 rtx i1, i2, last1, last2, afterlast1, afterlast2; | |
| 1067 int ninsns = 0; | |
| 1068 | |
| 1069 /* Skip simple jumps at the end of the blocks. Complex jumps still | |
| 1070 need to be compared for equivalence, which we'll do below. */ | |
| 1071 | |
| 1072 i1 = BB_END (bb1); | |
| 1073 last1 = afterlast1 = last2 = afterlast2 = NULL_RTX; | |
| 1074 if (onlyjump_p (i1) | |
| 1075 || (returnjump_p (i1) && !side_effects_p (PATTERN (i1)))) | |
| 1076 { | |
| 1077 last1 = i1; | |
| 1078 i1 = PREV_INSN (i1); | |
| 1079 } | |
| 1080 | |
| 1081 i2 = BB_END (bb2); | |
| 1082 if (onlyjump_p (i2) | |
| 1083 || (returnjump_p (i2) && !side_effects_p (PATTERN (i2)))) | |
| 1084 { | |
| 1085 last2 = i2; | |
| 1086 /* Count everything except for unconditional jump as insn. */ | |
| 1087 if (!simplejump_p (i2) && !returnjump_p (i2) && last1) | |
| 1088 ninsns++; | |
| 1089 i2 = PREV_INSN (i2); | |
| 1090 } | |
| 1091 | |
| 1092 while (true) | |
| 1093 { | |
| 1094 /* Ignore notes. */ | |
|
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1095 while (!NONDEBUG_INSN_P (i1) && i1 != BB_HEAD (bb1)) |
| 0 | 1096 i1 = PREV_INSN (i1); |
| 1097 | |
|
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1098 while (!NONDEBUG_INSN_P (i2) && i2 != BB_HEAD (bb2)) |
| 0 | 1099 i2 = PREV_INSN (i2); |
| 1100 | |
| 1101 if (i1 == BB_HEAD (bb1) || i2 == BB_HEAD (bb2)) | |
| 1102 break; | |
| 1103 | |
|
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1104 if (!old_insns_match_p (0, i1, i2)) |
| 0 | 1105 break; |
| 1106 | |
| 1107 merge_memattrs (i1, i2); | |
| 1108 | |
| 1109 /* Don't begin a cross-jump with a NOTE insn. */ | |
| 1110 if (INSN_P (i1)) | |
| 1111 { | |
|
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1112 merge_notes (i1, i2); |
| 0 | 1113 |
| 1114 afterlast1 = last1, afterlast2 = last2; | |
| 1115 last1 = i1, last2 = i2; | |
| 1116 ninsns++; | |
| 1117 } | |
| 1118 | |
| 1119 i1 = PREV_INSN (i1); | |
| 1120 i2 = PREV_INSN (i2); | |
| 1121 } | |
| 1122 | |
| 1123 #ifdef HAVE_cc0 | |
| 1124 /* Don't allow the insn after a compare to be shared by | |
| 1125 cross-jumping unless the compare is also shared. */ | |
| 1126 if (ninsns && reg_mentioned_p (cc0_rtx, last1) && ! sets_cc0_p (last1)) | |
| 1127 last1 = afterlast1, last2 = afterlast2, ninsns--; | |
| 1128 #endif | |
| 1129 | |
| 1130 /* Include preceding notes and labels in the cross-jump. One, | |
| 1131 this may bring us to the head of the blocks as requested above. | |
| 1132 Two, it keeps line number notes as matched as may be. */ | |
| 1133 if (ninsns) | |
| 1134 { | |
|
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1135 while (last1 != BB_HEAD (bb1) && !NONDEBUG_INSN_P (PREV_INSN (last1))) |
| 0 | 1136 last1 = PREV_INSN (last1); |
| 1137 | |
| 1138 if (last1 != BB_HEAD (bb1) && LABEL_P (PREV_INSN (last1))) | |
| 1139 last1 = PREV_INSN (last1); | |
| 1140 | |
|
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1141 while (last2 != BB_HEAD (bb2) && !NONDEBUG_INSN_P (PREV_INSN (last2))) |
| 0 | 1142 last2 = PREV_INSN (last2); |
| 1143 | |
| 1144 if (last2 != BB_HEAD (bb2) && LABEL_P (PREV_INSN (last2))) | |
| 1145 last2 = PREV_INSN (last2); | |
| 1146 | |
| 1147 *f1 = last1; | |
| 1148 *f2 = last2; | |
| 1149 } | |
| 1150 | |
| 1151 return ninsns; | |
| 1152 } | |
| 1153 | |
|
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1154 /* Like flow_find_cross_jump, except start looking for a matching sequence from |
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1155 the head of the two blocks. Do not include jumps at the end. |
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1156 If STOP_AFTER is nonzero, stop after finding that many matching |
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1157 instructions. */ |
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1158 |
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1159 int |
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1160 flow_find_head_matching_sequence (basic_block bb1, basic_block bb2, rtx *f1, |
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1161 rtx *f2, int stop_after) |
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1162 { |
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1163 rtx i1, i2, last1, last2, beforelast1, beforelast2; |
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1164 int ninsns = 0; |
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1165 edge e; |
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1166 edge_iterator ei; |
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1167 int nehedges1 = 0, nehedges2 = 0; |
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1168 |
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1169 FOR_EACH_EDGE (e, ei, bb1->succs) |
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1170 if (e->flags & EDGE_EH) |
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1171 nehedges1++; |
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1172 FOR_EACH_EDGE (e, ei, bb2->succs) |
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1173 if (e->flags & EDGE_EH) |
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1174 nehedges2++; |
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1175 |
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1176 i1 = BB_HEAD (bb1); |
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1177 i2 = BB_HEAD (bb2); |
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1178 last1 = beforelast1 = last2 = beforelast2 = NULL_RTX; |
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1179 |
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1180 while (true) |
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1181 { |
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1182 |
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1183 /* Ignore notes. */ |
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1184 while (!NONDEBUG_INSN_P (i1) && i1 != BB_END (bb1)) |
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1185 i1 = NEXT_INSN (i1); |
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1186 |
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1187 while (!NONDEBUG_INSN_P (i2) && i2 != BB_END (bb2)) |
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1188 i2 = NEXT_INSN (i2); |
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1189 |
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1190 if (NOTE_P (i1) || NOTE_P (i2) |
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1191 || JUMP_P (i1) || JUMP_P (i2)) |
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1192 break; |
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1193 |
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1194 /* A sanity check to make sure we're not merging insns with different |
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1195 effects on EH. If only one of them ends a basic block, it shouldn't |
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1196 have an EH edge; if both end a basic block, there should be the same |
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1197 number of EH edges. */ |
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1198 if ((i1 == BB_END (bb1) && i2 != BB_END (bb2) |
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1199 && nehedges1 > 0) |
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1200 || (i2 == BB_END (bb2) && i1 != BB_END (bb1) |
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1201 && nehedges2 > 0) |
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1202 || (i1 == BB_END (bb1) && i2 == BB_END (bb2) |
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1203 && nehedges1 != nehedges2)) |
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1204 break; |
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1205 |
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1206 if (!old_insns_match_p (0, i1, i2)) |
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1207 break; |
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1208 |
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1209 merge_memattrs (i1, i2); |
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1210 |
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1211 /* Don't begin a cross-jump with a NOTE insn. */ |
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1212 if (INSN_P (i1)) |
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1213 { |
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1214 merge_notes (i1, i2); |
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1215 |
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1216 beforelast1 = last1, beforelast2 = last2; |
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1217 last1 = i1, last2 = i2; |
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1218 ninsns++; |
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1219 } |
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1220 |
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1221 if (i1 == BB_END (bb1) || i2 == BB_END (bb2) |
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1222 || (stop_after > 0 && ninsns == stop_after)) |
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1223 break; |
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1224 |
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1225 i1 = NEXT_INSN (i1); |
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1226 i2 = NEXT_INSN (i2); |
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1227 } |
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1228 |
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1229 #ifdef HAVE_cc0 |
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1230 /* Don't allow a compare to be shared by cross-jumping unless the insn |
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1231 after the compare is also shared. */ |
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1232 if (ninsns && reg_mentioned_p (cc0_rtx, last1) && sets_cc0_p (last1)) |
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1233 last1 = beforelast1, last2 = beforelast2, ninsns--; |
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1234 #endif |
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1235 |
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1236 if (ninsns) |
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1237 { |
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1238 *f1 = last1; |
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1239 *f2 = last2; |
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1240 } |
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1241 |
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1242 return ninsns; |
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1243 } |
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1244 |
| 0 | 1245 /* Return true iff outgoing edges of BB1 and BB2 match, together with |
| 1246 the branch instruction. This means that if we commonize the control | |
| 1247 flow before end of the basic block, the semantic remains unchanged. | |
| 1248 | |
| 1249 We may assume that there exists one edge with a common destination. */ | |
| 1250 | |
| 1251 static bool | |
| 1252 outgoing_edges_match (int mode, basic_block bb1, basic_block bb2) | |
| 1253 { | |
| 1254 int nehedges1 = 0, nehedges2 = 0; | |
| 1255 edge fallthru1 = 0, fallthru2 = 0; | |
| 1256 edge e1, e2; | |
| 1257 edge_iterator ei; | |
| 1258 | |
| 1259 /* If BB1 has only one successor, we may be looking at either an | |
| 1260 unconditional jump, or a fake edge to exit. */ | |
| 1261 if (single_succ_p (bb1) | |
| 1262 && (single_succ_edge (bb1)->flags & (EDGE_COMPLEX | EDGE_FAKE)) == 0 | |
| 1263 && (!JUMP_P (BB_END (bb1)) || simplejump_p (BB_END (bb1)))) | |
| 1264 return (single_succ_p (bb2) | |
| 1265 && (single_succ_edge (bb2)->flags | |
| 1266 & (EDGE_COMPLEX | EDGE_FAKE)) == 0 | |
| 1267 && (!JUMP_P (BB_END (bb2)) || simplejump_p (BB_END (bb2)))); | |
| 1268 | |
| 1269 /* Match conditional jumps - this may get tricky when fallthru and branch | |
| 1270 edges are crossed. */ | |
| 1271 if (EDGE_COUNT (bb1->succs) == 2 | |
| 1272 && any_condjump_p (BB_END (bb1)) | |
| 1273 && onlyjump_p (BB_END (bb1))) | |
| 1274 { | |
| 1275 edge b1, f1, b2, f2; | |
| 1276 bool reverse, match; | |
| 1277 rtx set1, set2, cond1, cond2; | |
| 1278 enum rtx_code code1, code2; | |
| 1279 | |
| 1280 if (EDGE_COUNT (bb2->succs) != 2 | |
| 1281 || !any_condjump_p (BB_END (bb2)) | |
| 1282 || !onlyjump_p (BB_END (bb2))) | |
| 1283 return false; | |
| 1284 | |
| 1285 b1 = BRANCH_EDGE (bb1); | |
| 1286 b2 = BRANCH_EDGE (bb2); | |
| 1287 f1 = FALLTHRU_EDGE (bb1); | |
| 1288 f2 = FALLTHRU_EDGE (bb2); | |
| 1289 | |
| 1290 /* Get around possible forwarders on fallthru edges. Other cases | |
| 1291 should be optimized out already. */ | |
| 1292 if (FORWARDER_BLOCK_P (f1->dest)) | |
| 1293 f1 = single_succ_edge (f1->dest); | |
| 1294 | |
| 1295 if (FORWARDER_BLOCK_P (f2->dest)) | |
| 1296 f2 = single_succ_edge (f2->dest); | |
| 1297 | |
| 1298 /* To simplify use of this function, return false if there are | |
| 1299 unneeded forwarder blocks. These will get eliminated later | |
| 1300 during cleanup_cfg. */ | |
| 1301 if (FORWARDER_BLOCK_P (f1->dest) | |
| 1302 || FORWARDER_BLOCK_P (f2->dest) | |
| 1303 || FORWARDER_BLOCK_P (b1->dest) | |
| 1304 || FORWARDER_BLOCK_P (b2->dest)) | |
| 1305 return false; | |
| 1306 | |
| 1307 if (f1->dest == f2->dest && b1->dest == b2->dest) | |
| 1308 reverse = false; | |
| 1309 else if (f1->dest == b2->dest && b1->dest == f2->dest) | |
| 1310 reverse = true; | |
| 1311 else | |
| 1312 return false; | |
| 1313 | |
| 1314 set1 = pc_set (BB_END (bb1)); | |
| 1315 set2 = pc_set (BB_END (bb2)); | |
| 1316 if ((XEXP (SET_SRC (set1), 1) == pc_rtx) | |
| 1317 != (XEXP (SET_SRC (set2), 1) == pc_rtx)) | |
| 1318 reverse = !reverse; | |
| 1319 | |
| 1320 cond1 = XEXP (SET_SRC (set1), 0); | |
| 1321 cond2 = XEXP (SET_SRC (set2), 0); | |
| 1322 code1 = GET_CODE (cond1); | |
| 1323 if (reverse) | |
| 1324 code2 = reversed_comparison_code (cond2, BB_END (bb2)); | |
| 1325 else | |
| 1326 code2 = GET_CODE (cond2); | |
| 1327 | |
| 1328 if (code2 == UNKNOWN) | |
| 1329 return false; | |
| 1330 | |
| 1331 /* Verify codes and operands match. */ | |
| 1332 match = ((code1 == code2 | |
| 1333 && rtx_renumbered_equal_p (XEXP (cond1, 0), XEXP (cond2, 0)) | |
| 1334 && rtx_renumbered_equal_p (XEXP (cond1, 1), XEXP (cond2, 1))) | |
| 1335 || (code1 == swap_condition (code2) | |
| 1336 && rtx_renumbered_equal_p (XEXP (cond1, 1), | |
| 1337 XEXP (cond2, 0)) | |
| 1338 && rtx_renumbered_equal_p (XEXP (cond1, 0), | |
| 1339 XEXP (cond2, 1)))); | |
| 1340 | |
| 1341 /* If we return true, we will join the blocks. Which means that | |
| 1342 we will only have one branch prediction bit to work with. Thus | |
| 1343 we require the existing branches to have probabilities that are | |
| 1344 roughly similar. */ | |
| 1345 if (match | |
| 1346 && optimize_bb_for_speed_p (bb1) | |
| 1347 && optimize_bb_for_speed_p (bb2)) | |
| 1348 { | |
| 1349 int prob2; | |
| 1350 | |
| 1351 if (b1->dest == b2->dest) | |
| 1352 prob2 = b2->probability; | |
| 1353 else | |
| 1354 /* Do not use f2 probability as f2 may be forwarded. */ | |
| 1355 prob2 = REG_BR_PROB_BASE - b2->probability; | |
| 1356 | |
| 1357 /* Fail if the difference in probabilities is greater than 50%. | |
| 1358 This rules out two well-predicted branches with opposite | |
| 1359 outcomes. */ | |
| 1360 if (abs (b1->probability - prob2) > REG_BR_PROB_BASE / 2) | |
| 1361 { | |
| 1362 if (dump_file) | |
| 1363 fprintf (dump_file, | |
| 1364 "Outcomes of branch in bb %i and %i differ too much (%i %i)\n", | |
| 1365 bb1->index, bb2->index, b1->probability, prob2); | |
| 1366 | |
| 1367 return false; | |
| 1368 } | |
| 1369 } | |
| 1370 | |
| 1371 if (dump_file && match) | |
| 1372 fprintf (dump_file, "Conditionals in bb %i and %i match.\n", | |
| 1373 bb1->index, bb2->index); | |
| 1374 | |
| 1375 return match; | |
| 1376 } | |
| 1377 | |
| 1378 /* Generic case - we are seeing a computed jump, table jump or trapping | |
| 1379 instruction. */ | |
| 1380 | |
| 1381 /* Check whether there are tablejumps in the end of BB1 and BB2. | |
| 1382 Return true if they are identical. */ | |
| 1383 { | |
| 1384 rtx label1, label2; | |
| 1385 rtx table1, table2; | |
| 1386 | |
| 1387 if (tablejump_p (BB_END (bb1), &label1, &table1) | |
| 1388 && tablejump_p (BB_END (bb2), &label2, &table2) | |
| 1389 && GET_CODE (PATTERN (table1)) == GET_CODE (PATTERN (table2))) | |
| 1390 { | |
| 1391 /* The labels should never be the same rtx. If they really are same | |
| 1392 the jump tables are same too. So disable crossjumping of blocks BB1 | |
| 1393 and BB2 because when deleting the common insns in the end of BB1 | |
| 1394 by delete_basic_block () the jump table would be deleted too. */ | |
| 1395 /* If LABEL2 is referenced in BB1->END do not do anything | |
| 1396 because we would loose information when replacing | |
| 1397 LABEL1 by LABEL2 and then LABEL2 by LABEL1 in BB1->END. */ | |
| 1398 if (label1 != label2 && !rtx_referenced_p (label2, BB_END (bb1))) | |
| 1399 { | |
| 1400 /* Set IDENTICAL to true when the tables are identical. */ | |
| 1401 bool identical = false; | |
| 1402 rtx p1, p2; | |
| 1403 | |
| 1404 p1 = PATTERN (table1); | |
| 1405 p2 = PATTERN (table2); | |
| 1406 if (GET_CODE (p1) == ADDR_VEC && rtx_equal_p (p1, p2)) | |
| 1407 { | |
| 1408 identical = true; | |
| 1409 } | |
| 1410 else if (GET_CODE (p1) == ADDR_DIFF_VEC | |
| 1411 && (XVECLEN (p1, 1) == XVECLEN (p2, 1)) | |
| 1412 && rtx_equal_p (XEXP (p1, 2), XEXP (p2, 2)) | |
| 1413 && rtx_equal_p (XEXP (p1, 3), XEXP (p2, 3))) | |
| 1414 { | |
| 1415 int i; | |
| 1416 | |
| 1417 identical = true; | |
| 1418 for (i = XVECLEN (p1, 1) - 1; i >= 0 && identical; i--) | |
| 1419 if (!rtx_equal_p (XVECEXP (p1, 1, i), XVECEXP (p2, 1, i))) | |
| 1420 identical = false; | |
| 1421 } | |
| 1422 | |
| 1423 if (identical) | |
| 1424 { | |
| 1425 replace_label_data rr; | |
| 1426 bool match; | |
| 1427 | |
| 1428 /* Temporarily replace references to LABEL1 with LABEL2 | |
| 1429 in BB1->END so that we could compare the instructions. */ | |
| 1430 rr.r1 = label1; | |
| 1431 rr.r2 = label2; | |
| 1432 rr.update_label_nuses = false; | |
| 1433 for_each_rtx (&BB_END (bb1), replace_label, &rr); | |
| 1434 | |
| 1435 match = old_insns_match_p (mode, BB_END (bb1), BB_END (bb2)); | |
| 1436 if (dump_file && match) | |
| 1437 fprintf (dump_file, | |
| 1438 "Tablejumps in bb %i and %i match.\n", | |
| 1439 bb1->index, bb2->index); | |
| 1440 | |
| 1441 /* Set the original label in BB1->END because when deleting | |
| 1442 a block whose end is a tablejump, the tablejump referenced | |
| 1443 from the instruction is deleted too. */ | |
| 1444 rr.r1 = label2; | |
| 1445 rr.r2 = label1; | |
| 1446 for_each_rtx (&BB_END (bb1), replace_label, &rr); | |
| 1447 | |
| 1448 return match; | |
| 1449 } | |
| 1450 } | |
| 1451 return false; | |
| 1452 } | |
| 1453 } | |
| 1454 | |
| 1455 /* First ensure that the instructions match. There may be many outgoing | |
| 1456 edges so this test is generally cheaper. */ | |
| 1457 if (!old_insns_match_p (mode, BB_END (bb1), BB_END (bb2))) | |
| 1458 return false; | |
| 1459 | |
| 1460 /* Search the outgoing edges, ensure that the counts do match, find possible | |
| 1461 fallthru and exception handling edges since these needs more | |
| 1462 validation. */ | |
| 1463 if (EDGE_COUNT (bb1->succs) != EDGE_COUNT (bb2->succs)) | |
| 1464 return false; | |
| 1465 | |
| 1466 FOR_EACH_EDGE (e1, ei, bb1->succs) | |
| 1467 { | |
| 1468 e2 = EDGE_SUCC (bb2, ei.index); | |
| 1469 | |
| 1470 if (e1->flags & EDGE_EH) | |
| 1471 nehedges1++; | |
| 1472 | |
| 1473 if (e2->flags & EDGE_EH) | |
| 1474 nehedges2++; | |
| 1475 | |
| 1476 if (e1->flags & EDGE_FALLTHRU) | |
| 1477 fallthru1 = e1; | |
| 1478 if (e2->flags & EDGE_FALLTHRU) | |
| 1479 fallthru2 = e2; | |
| 1480 } | |
| 1481 | |
| 1482 /* If number of edges of various types does not match, fail. */ | |
| 1483 if (nehedges1 != nehedges2 | |
| 1484 || (fallthru1 != 0) != (fallthru2 != 0)) | |
| 1485 return false; | |
| 1486 | |
| 1487 /* fallthru edges must be forwarded to the same destination. */ | |
| 1488 if (fallthru1) | |
| 1489 { | |
| 1490 basic_block d1 = (forwarder_block_p (fallthru1->dest) | |
| 1491 ? single_succ (fallthru1->dest): fallthru1->dest); | |
| 1492 basic_block d2 = (forwarder_block_p (fallthru2->dest) | |
| 1493 ? single_succ (fallthru2->dest): fallthru2->dest); | |
| 1494 | |
| 1495 if (d1 != d2) | |
| 1496 return false; | |
| 1497 } | |
| 1498 | |
| 1499 /* Ensure the same EH region. */ | |
| 1500 { | |
| 1501 rtx n1 = find_reg_note (BB_END (bb1), REG_EH_REGION, 0); | |
| 1502 rtx n2 = find_reg_note (BB_END (bb2), REG_EH_REGION, 0); | |
| 1503 | |
| 1504 if (!n1 && n2) | |
| 1505 return false; | |
| 1506 | |
| 1507 if (n1 && (!n2 || XEXP (n1, 0) != XEXP (n2, 0))) | |
| 1508 return false; | |
| 1509 } | |
| 1510 | |
| 1511 /* The same checks as in try_crossjump_to_edge. It is required for RTL | |
| 1512 version of sequence abstraction. */ | |
| 1513 FOR_EACH_EDGE (e1, ei, bb2->succs) | |
| 1514 { | |
| 1515 edge e2; | |
| 1516 edge_iterator ei; | |
| 1517 basic_block d1 = e1->dest; | |
| 1518 | |
| 1519 if (FORWARDER_BLOCK_P (d1)) | |
| 1520 d1 = EDGE_SUCC (d1, 0)->dest; | |
| 1521 | |
| 1522 FOR_EACH_EDGE (e2, ei, bb1->succs) | |
| 1523 { | |
| 1524 basic_block d2 = e2->dest; | |
| 1525 if (FORWARDER_BLOCK_P (d2)) | |
| 1526 d2 = EDGE_SUCC (d2, 0)->dest; | |
| 1527 if (d1 == d2) | |
| 1528 break; | |
| 1529 } | |
| 1530 | |
| 1531 if (!e2) | |
| 1532 return false; | |
| 1533 } | |
| 1534 | |
| 1535 return true; | |
| 1536 } | |
| 1537 | |
| 1538 /* Returns true if BB basic block has a preserve label. */ | |
| 1539 | |
| 1540 static bool | |
| 1541 block_has_preserve_label (basic_block bb) | |
| 1542 { | |
| 1543 return (bb | |
| 1544 && block_label (bb) | |
| 1545 && LABEL_PRESERVE_P (block_label (bb))); | |
| 1546 } | |
| 1547 | |
| 1548 /* E1 and E2 are edges with the same destination block. Search their | |
| 1549 predecessors for common code. If found, redirect control flow from | |
| 1550 (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC. */ | |
| 1551 | |
| 1552 static bool | |
| 1553 try_crossjump_to_edge (int mode, edge e1, edge e2) | |
| 1554 { | |
| 1555 int nmatch; | |
| 1556 basic_block src1 = e1->src, src2 = e2->src; | |
| 1557 basic_block redirect_to, redirect_from, to_remove; | |
| 1558 rtx newpos1, newpos2; | |
| 1559 edge s; | |
| 1560 edge_iterator ei; | |
| 1561 | |
| 1562 newpos1 = newpos2 = NULL_RTX; | |
| 1563 | |
| 1564 /* If we have partitioned hot/cold basic blocks, it is a bad idea | |
| 1565 to try this optimization. | |
| 1566 | |
| 1567 Basic block partitioning may result in some jumps that appear to | |
| 1568 be optimizable (or blocks that appear to be mergeable), but which really | |
| 1569 must be left untouched (they are required to make it safely across | |
| 1570 partition boundaries). See the comments at the top of | |
| 1571 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 1572 | |
| 1573 if (flag_reorder_blocks_and_partition && reload_completed) | |
| 1574 return false; | |
| 1575 | |
| 1576 /* Search backward through forwarder blocks. We don't need to worry | |
| 1577 about multiple entry or chained forwarders, as they will be optimized | |
| 1578 away. We do this to look past the unconditional jump following a | |
| 1579 conditional jump that is required due to the current CFG shape. */ | |
| 1580 if (single_pred_p (src1) | |
| 1581 && FORWARDER_BLOCK_P (src1)) | |
| 1582 e1 = single_pred_edge (src1), src1 = e1->src; | |
| 1583 | |
| 1584 if (single_pred_p (src2) | |
| 1585 && FORWARDER_BLOCK_P (src2)) | |
| 1586 e2 = single_pred_edge (src2), src2 = e2->src; | |
| 1587 | |
| 1588 /* Nothing to do if we reach ENTRY, or a common source block. */ | |
| 1589 if (src1 == ENTRY_BLOCK_PTR || src2 == ENTRY_BLOCK_PTR) | |
| 1590 return false; | |
| 1591 if (src1 == src2) | |
| 1592 return false; | |
| 1593 | |
| 1594 /* Seeing more than 1 forwarder blocks would confuse us later... */ | |
| 1595 if (FORWARDER_BLOCK_P (e1->dest) | |
| 1596 && FORWARDER_BLOCK_P (single_succ (e1->dest))) | |
| 1597 return false; | |
| 1598 | |
| 1599 if (FORWARDER_BLOCK_P (e2->dest) | |
| 1600 && FORWARDER_BLOCK_P (single_succ (e2->dest))) | |
| 1601 return false; | |
| 1602 | |
| 1603 /* Likewise with dead code (possibly newly created by the other optimizations | |
| 1604 of cfg_cleanup). */ | |
| 1605 if (EDGE_COUNT (src1->preds) == 0 || EDGE_COUNT (src2->preds) == 0) | |
| 1606 return false; | |
| 1607 | |
| 1608 /* Look for the common insn sequence, part the first ... */ | |
| 1609 if (!outgoing_edges_match (mode, src1, src2)) | |
| 1610 return false; | |
| 1611 | |
| 1612 /* ... and part the second. */ | |
|
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1613 nmatch = flow_find_cross_jump (src1, src2, &newpos1, &newpos2); |
| 0 | 1614 |
| 1615 /* Don't proceed with the crossjump unless we found a sufficient number | |
| 1616 of matching instructions or the 'from' block was totally matched | |
| 1617 (such that its predecessors will hopefully be redirected and the | |
| 1618 block removed). */ | |
| 1619 if ((nmatch < PARAM_VALUE (PARAM_MIN_CROSSJUMP_INSNS)) | |
| 1620 && (newpos1 != BB_HEAD (src1))) | |
| 1621 return false; | |
| 1622 | |
| 1623 /* Avoid deleting preserve label when redirecting ABNORMAL edges. */ | |
| 1624 if (block_has_preserve_label (e1->dest) | |
| 1625 && (e1->flags & EDGE_ABNORMAL)) | |
| 1626 return false; | |
| 1627 | |
| 1628 /* Here we know that the insns in the end of SRC1 which are common with SRC2 | |
| 1629 will be deleted. | |
| 1630 If we have tablejumps in the end of SRC1 and SRC2 | |
| 1631 they have been already compared for equivalence in outgoing_edges_match () | |
| 1632 so replace the references to TABLE1 by references to TABLE2. */ | |
| 1633 { | |
| 1634 rtx label1, label2; | |
| 1635 rtx table1, table2; | |
| 1636 | |
| 1637 if (tablejump_p (BB_END (src1), &label1, &table1) | |
| 1638 && tablejump_p (BB_END (src2), &label2, &table2) | |
| 1639 && label1 != label2) | |
| 1640 { | |
| 1641 replace_label_data rr; | |
| 1642 rtx insn; | |
| 1643 | |
| 1644 /* Replace references to LABEL1 with LABEL2. */ | |
| 1645 rr.r1 = label1; | |
| 1646 rr.r2 = label2; | |
| 1647 rr.update_label_nuses = true; | |
| 1648 for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) | |
| 1649 { | |
| 1650 /* Do not replace the label in SRC1->END because when deleting | |
| 1651 a block whose end is a tablejump, the tablejump referenced | |
| 1652 from the instruction is deleted too. */ | |
| 1653 if (insn != BB_END (src1)) | |
| 1654 for_each_rtx (&insn, replace_label, &rr); | |
| 1655 } | |
| 1656 } | |
| 1657 } | |
| 1658 | |
| 1659 /* Avoid splitting if possible. We must always split when SRC2 has | |
| 1660 EH predecessor edges, or we may end up with basic blocks with both | |
| 1661 normal and EH predecessor edges. */ | |
| 1662 if (newpos2 == BB_HEAD (src2) | |
| 1663 && !(EDGE_PRED (src2, 0)->flags & EDGE_EH)) | |
| 1664 redirect_to = src2; | |
| 1665 else | |
| 1666 { | |
| 1667 if (newpos2 == BB_HEAD (src2)) | |
| 1668 { | |
| 1669 /* Skip possible basic block header. */ | |
| 1670 if (LABEL_P (newpos2)) | |
| 1671 newpos2 = NEXT_INSN (newpos2); | |
|
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1672 while (DEBUG_INSN_P (newpos2)) |
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1673 newpos2 = NEXT_INSN (newpos2); |
| 0 | 1674 if (NOTE_P (newpos2)) |
| 1675 newpos2 = NEXT_INSN (newpos2); | |
|
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1676 while (DEBUG_INSN_P (newpos2)) |
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1677 newpos2 = NEXT_INSN (newpos2); |
| 0 | 1678 } |
| 1679 | |
| 1680 if (dump_file) | |
| 1681 fprintf (dump_file, "Splitting bb %i before %i insns\n", | |
| 1682 src2->index, nmatch); | |
| 1683 redirect_to = split_block (src2, PREV_INSN (newpos2))->dest; | |
| 1684 } | |
| 1685 | |
| 1686 if (dump_file) | |
| 1687 fprintf (dump_file, | |
| 1688 "Cross jumping from bb %i to bb %i; %i common insns\n", | |
| 1689 src1->index, src2->index, nmatch); | |
| 1690 | |
| 1691 /* We may have some registers visible through the block. */ | |
| 1692 df_set_bb_dirty (redirect_to); | |
| 1693 | |
| 1694 /* Recompute the frequencies and counts of outgoing edges. */ | |
| 1695 FOR_EACH_EDGE (s, ei, redirect_to->succs) | |
| 1696 { | |
| 1697 edge s2; | |
| 1698 edge_iterator ei; | |
| 1699 basic_block d = s->dest; | |
| 1700 | |
| 1701 if (FORWARDER_BLOCK_P (d)) | |
| 1702 d = single_succ (d); | |
| 1703 | |
| 1704 FOR_EACH_EDGE (s2, ei, src1->succs) | |
| 1705 { | |
| 1706 basic_block d2 = s2->dest; | |
| 1707 if (FORWARDER_BLOCK_P (d2)) | |
| 1708 d2 = single_succ (d2); | |
| 1709 if (d == d2) | |
| 1710 break; | |
| 1711 } | |
| 1712 | |
| 1713 s->count += s2->count; | |
| 1714 | |
| 1715 /* Take care to update possible forwarder blocks. We verified | |
| 1716 that there is no more than one in the chain, so we can't run | |
| 1717 into infinite loop. */ | |
| 1718 if (FORWARDER_BLOCK_P (s->dest)) | |
| 1719 { | |
| 1720 single_succ_edge (s->dest)->count += s2->count; | |
| 1721 s->dest->count += s2->count; | |
| 1722 s->dest->frequency += EDGE_FREQUENCY (s); | |
| 1723 } | |
| 1724 | |
| 1725 if (FORWARDER_BLOCK_P (s2->dest)) | |
| 1726 { | |
| 1727 single_succ_edge (s2->dest)->count -= s2->count; | |
| 1728 if (single_succ_edge (s2->dest)->count < 0) | |
| 1729 single_succ_edge (s2->dest)->count = 0; | |
| 1730 s2->dest->count -= s2->count; | |
| 1731 s2->dest->frequency -= EDGE_FREQUENCY (s); | |
| 1732 if (s2->dest->frequency < 0) | |
| 1733 s2->dest->frequency = 0; | |
| 1734 if (s2->dest->count < 0) | |
| 1735 s2->dest->count = 0; | |
| 1736 } | |
| 1737 | |
| 1738 if (!redirect_to->frequency && !src1->frequency) | |
| 1739 s->probability = (s->probability + s2->probability) / 2; | |
| 1740 else | |
| 1741 s->probability | |
| 1742 = ((s->probability * redirect_to->frequency + | |
| 1743 s2->probability * src1->frequency) | |
| 1744 / (redirect_to->frequency + src1->frequency)); | |
| 1745 } | |
| 1746 | |
| 1747 /* Adjust count and frequency for the block. An earlier jump | |
| 1748 threading pass may have left the profile in an inconsistent | |
| 1749 state (see update_bb_profile_for_threading) so we must be | |
| 1750 prepared for overflows. */ | |
| 1751 redirect_to->count += src1->count; | |
| 1752 redirect_to->frequency += src1->frequency; | |
| 1753 if (redirect_to->frequency > BB_FREQ_MAX) | |
| 1754 redirect_to->frequency = BB_FREQ_MAX; | |
| 1755 update_br_prob_note (redirect_to); | |
| 1756 | |
| 1757 /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */ | |
| 1758 | |
| 1759 /* Skip possible basic block header. */ | |
| 1760 if (LABEL_P (newpos1)) | |
| 1761 newpos1 = NEXT_INSN (newpos1); | |
| 1762 | |
|
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1763 while (DEBUG_INSN_P (newpos1)) |
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1764 newpos1 = NEXT_INSN (newpos1); |
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1765 |
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1766 if (NOTE_INSN_BASIC_BLOCK_P (newpos1)) |
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1767 newpos1 = NEXT_INSN (newpos1); |
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1768 |
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1769 while (DEBUG_INSN_P (newpos1)) |
| 0 | 1770 newpos1 = NEXT_INSN (newpos1); |
| 1771 | |
| 1772 redirect_from = split_block (src1, PREV_INSN (newpos1))->src; | |
| 1773 to_remove = single_succ (redirect_from); | |
| 1774 | |
| 1775 redirect_edge_and_branch_force (single_succ_edge (redirect_from), redirect_to); | |
| 1776 delete_basic_block (to_remove); | |
| 1777 | |
| 1778 update_forwarder_flag (redirect_from); | |
| 1779 if (redirect_to != src2) | |
| 1780 update_forwarder_flag (src2); | |
| 1781 | |
| 1782 return true; | |
| 1783 } | |
| 1784 | |
| 1785 /* Search the predecessors of BB for common insn sequences. When found, | |
| 1786 share code between them by redirecting control flow. Return true if | |
| 1787 any changes made. */ | |
| 1788 | |
| 1789 static bool | |
| 1790 try_crossjump_bb (int mode, basic_block bb) | |
| 1791 { | |
| 1792 edge e, e2, fallthru; | |
| 1793 bool changed; | |
| 1794 unsigned max, ix, ix2; | |
| 1795 basic_block ev, ev2; | |
| 1796 edge_iterator ei; | |
| 1797 | |
| 1798 /* Nothing to do if there is not at least two incoming edges. */ | |
| 1799 if (EDGE_COUNT (bb->preds) < 2) | |
| 1800 return false; | |
| 1801 | |
| 1802 /* Don't crossjump if this block ends in a computed jump, | |
| 1803 unless we are optimizing for size. */ | |
| 1804 if (optimize_bb_for_size_p (bb) | |
| 1805 && bb != EXIT_BLOCK_PTR | |
| 1806 && computed_jump_p (BB_END (bb))) | |
| 1807 return false; | |
| 1808 | |
| 1809 /* If we are partitioning hot/cold basic blocks, we don't want to | |
| 1810 mess up unconditional or indirect jumps that cross between hot | |
| 1811 and cold sections. | |
| 1812 | |
| 1813 Basic block partitioning may result in some jumps that appear to | |
| 1814 be optimizable (or blocks that appear to be mergeable), but which really | |
| 1815 must be left untouched (they are required to make it safely across | |
| 1816 partition boundaries). See the comments at the top of | |
| 1817 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ | |
| 1818 | |
| 1819 if (BB_PARTITION (EDGE_PRED (bb, 0)->src) != | |
| 1820 BB_PARTITION (EDGE_PRED (bb, 1)->src) | |
| 1821 || (EDGE_PRED (bb, 0)->flags & EDGE_CROSSING)) | |
| 1822 return false; | |
| 1823 | |
| 1824 /* It is always cheapest to redirect a block that ends in a branch to | |
| 1825 a block that falls through into BB, as that adds no branches to the | |
| 1826 program. We'll try that combination first. */ | |
| 1827 fallthru = NULL; | |
| 1828 max = PARAM_VALUE (PARAM_MAX_CROSSJUMP_EDGES); | |
| 1829 | |
| 1830 if (EDGE_COUNT (bb->preds) > max) | |
| 1831 return false; | |
| 1832 | |
| 1833 FOR_EACH_EDGE (e, ei, bb->preds) | |
| 1834 { | |
| 1835 if (e->flags & EDGE_FALLTHRU) | |
| 1836 { | |
| 1837 fallthru = e; | |
| 1838 break; | |
| 1839 } | |
| 1840 } | |
| 1841 | |
| 1842 changed = false; | |
| 1843 for (ix = 0, ev = bb; ix < EDGE_COUNT (ev->preds); ) | |
| 1844 { | |
| 1845 e = EDGE_PRED (ev, ix); | |
| 1846 ix++; | |
| 1847 | |
| 1848 /* As noted above, first try with the fallthru predecessor (or, a | |
| 1849 fallthru predecessor if we are in cfglayout mode). */ | |
| 1850 if (fallthru) | |
| 1851 { | |
| 1852 /* Don't combine the fallthru edge into anything else. | |
| 1853 If there is a match, we'll do it the other way around. */ | |
| 1854 if (e == fallthru) | |
| 1855 continue; | |
| 1856 /* If nothing changed since the last attempt, there is nothing | |
| 1857 we can do. */ | |
| 1858 if (!first_pass | |
| 1859 && (!(df_get_bb_dirty (e->src)) | |
| 1860 && !(df_get_bb_dirty (fallthru->src)))) | |
| 1861 continue; | |
| 1862 | |
| 1863 if (try_crossjump_to_edge (mode, e, fallthru)) | |
| 1864 { | |
| 1865 changed = true; | |
| 1866 ix = 0; | |
| 1867 ev = bb; | |
| 1868 continue; | |
| 1869 } | |
| 1870 } | |
| 1871 | |
| 1872 /* Non-obvious work limiting check: Recognize that we're going | |
| 1873 to call try_crossjump_bb on every basic block. So if we have | |
| 1874 two blocks with lots of outgoing edges (a switch) and they | |
| 1875 share lots of common destinations, then we would do the | |
| 1876 cross-jump check once for each common destination. | |
| 1877 | |
| 1878 Now, if the blocks actually are cross-jump candidates, then | |
| 1879 all of their destinations will be shared. Which means that | |
| 1880 we only need check them for cross-jump candidacy once. We | |
| 1881 can eliminate redundant checks of crossjump(A,B) by arbitrarily | |
| 1882 choosing to do the check from the block for which the edge | |
| 1883 in question is the first successor of A. */ | |
| 1884 if (EDGE_SUCC (e->src, 0) != e) | |
| 1885 continue; | |
| 1886 | |
| 1887 for (ix2 = 0, ev2 = bb; ix2 < EDGE_COUNT (ev2->preds); ) | |
| 1888 { | |
| 1889 e2 = EDGE_PRED (ev2, ix2); | |
| 1890 ix2++; | |
| 1891 | |
| 1892 if (e2 == e) | |
| 1893 continue; | |
| 1894 | |
| 1895 /* We've already checked the fallthru edge above. */ | |
| 1896 if (e2 == fallthru) | |
| 1897 continue; | |
| 1898 | |
| 1899 /* The "first successor" check above only prevents multiple | |
| 1900 checks of crossjump(A,B). In order to prevent redundant | |
| 1901 checks of crossjump(B,A), require that A be the block | |
| 1902 with the lowest index. */ | |
| 1903 if (e->src->index > e2->src->index) | |
| 1904 continue; | |
| 1905 | |
| 1906 /* If nothing changed since the last attempt, there is nothing | |
| 1907 we can do. */ | |
| 1908 if (!first_pass | |
| 1909 && (!(df_get_bb_dirty (e->src)) | |
| 1910 && !(df_get_bb_dirty (e2->src)))) | |
| 1911 continue; | |
| 1912 | |
| 1913 if (try_crossjump_to_edge (mode, e, e2)) | |
| 1914 { | |
| 1915 changed = true; | |
| 1916 ev2 = bb; | |
| 1917 ix = 0; | |
| 1918 break; | |
| 1919 } | |
| 1920 } | |
| 1921 } | |
| 1922 | |
| 1923 if (changed) | |
| 1924 crossjumps_occured = true; | |
| 1925 | |
| 1926 return changed; | |
| 1927 } | |
| 1928 | |
|
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1929 /* Return true if BB contains just bb note, or bb note followed |
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1930 by only DEBUG_INSNs. */ |
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1931 |
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1932 static bool |
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1933 trivially_empty_bb_p (basic_block bb) |
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1934 { |
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1935 rtx insn = BB_END (bb); |
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1936 |
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1937 while (1) |
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1938 { |
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1939 if (insn == BB_HEAD (bb)) |
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1940 return true; |
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1941 if (!DEBUG_INSN_P (insn)) |
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1942 return false; |
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1943 insn = PREV_INSN (insn); |
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1944 } |
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1945 } |
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1946 |
| 0 | 1947 /* Do simple CFG optimizations - basic block merging, simplifying of jump |
| 1948 instructions etc. Return nonzero if changes were made. */ | |
| 1949 | |
| 1950 static bool | |
| 1951 try_optimize_cfg (int mode) | |
| 1952 { | |
| 1953 bool changed_overall = false; | |
| 1954 bool changed; | |
| 1955 int iterations = 0; | |
| 1956 basic_block bb, b, next; | |
| 1957 | |
| 1958 if (mode & (CLEANUP_CROSSJUMP | CLEANUP_THREADING)) | |
| 1959 clear_bb_flags (); | |
| 1960 | |
| 1961 crossjumps_occured = false; | |
| 1962 | |
| 1963 FOR_EACH_BB (bb) | |
| 1964 update_forwarder_flag (bb); | |
| 1965 | |
| 1966 if (! targetm.cannot_modify_jumps_p ()) | |
| 1967 { | |
| 1968 first_pass = true; | |
| 1969 /* Attempt to merge blocks as made possible by edge removal. If | |
| 1970 a block has only one successor, and the successor has only | |
| 1971 one predecessor, they may be combined. */ | |
| 1972 do | |
| 1973 { | |
| 1974 changed = false; | |
| 1975 iterations++; | |
| 1976 | |
| 1977 if (dump_file) | |
| 1978 fprintf (dump_file, | |
| 1979 "\n\ntry_optimize_cfg iteration %i\n\n", | |
| 1980 iterations); | |
| 1981 | |
| 1982 for (b = ENTRY_BLOCK_PTR->next_bb; b != EXIT_BLOCK_PTR;) | |
| 1983 { | |
| 1984 basic_block c; | |
| 1985 edge s; | |
| 1986 bool changed_here = false; | |
| 1987 | |
|
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1988 /* Delete trivially dead basic blocks. This is either |
|
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1989 blocks with no predecessors, or empty blocks with no |
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1990 successors. However if the empty block with no |
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1991 successors is the successor of the ENTRY_BLOCK, it is |
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1992 kept. This ensures that the ENTRY_BLOCK will have a |
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1993 successor which is a precondition for many RTL |
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1994 passes. Empty blocks may result from expanding |
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1995 __builtin_unreachable (). */ |
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1996 if (EDGE_COUNT (b->preds) == 0 |
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1997 || (EDGE_COUNT (b->succs) == 0 |
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1998 && trivially_empty_bb_p (b) |
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1999 && single_succ_edge (ENTRY_BLOCK_PTR)->dest != b)) |
| 0 | 2000 { |
| 2001 c = b->prev_bb; | |
|
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2002 if (EDGE_COUNT (b->preds) > 0) |
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2003 { |
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2004 edge e; |
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2005 edge_iterator ei; |
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2006 |
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2007 if (current_ir_type () == IR_RTL_CFGLAYOUT) |
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2008 { |
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2009 if (b->il.rtl->footer |
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2010 && BARRIER_P (b->il.rtl->footer)) |
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2011 FOR_EACH_EDGE (e, ei, b->preds) |
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2012 if ((e->flags & EDGE_FALLTHRU) |
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2013 && e->src->il.rtl->footer == NULL) |
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2014 { |
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2015 if (b->il.rtl->footer) |
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2016 { |
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2017 e->src->il.rtl->footer = b->il.rtl->footer; |
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2018 b->il.rtl->footer = NULL; |
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2019 } |
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2020 else |
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2021 { |
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2022 start_sequence (); |
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2023 e->src->il.rtl->footer = emit_barrier (); |
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2024 end_sequence (); |
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2025 } |
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2026 } |
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2027 } |
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2028 else |
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2029 { |
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2030 rtx last = get_last_bb_insn (b); |
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2031 if (last && BARRIER_P (last)) |
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2032 FOR_EACH_EDGE (e, ei, b->preds) |
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2033 if ((e->flags & EDGE_FALLTHRU)) |
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2034 emit_barrier_after (BB_END (e->src)); |
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2035 } |
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2036 } |
| 0 | 2037 delete_basic_block (b); |
| 2038 if (!(mode & CLEANUP_CFGLAYOUT)) | |
| 2039 changed = true; | |
| 2040 /* Avoid trying to remove ENTRY_BLOCK_PTR. */ | |
| 2041 b = (c == ENTRY_BLOCK_PTR ? c->next_bb : c); | |
| 2042 continue; | |
| 2043 } | |
| 2044 | |
| 2045 /* Remove code labels no longer used. */ | |
| 2046 if (single_pred_p (b) | |
| 2047 && (single_pred_edge (b)->flags & EDGE_FALLTHRU) | |
| 2048 && !(single_pred_edge (b)->flags & EDGE_COMPLEX) | |
| 2049 && LABEL_P (BB_HEAD (b)) | |
| 2050 /* If the previous block ends with a branch to this | |
| 2051 block, we can't delete the label. Normally this | |
| 2052 is a condjump that is yet to be simplified, but | |
| 2053 if CASE_DROPS_THRU, this can be a tablejump with | |
| 2054 some element going to the same place as the | |
| 2055 default (fallthru). */ | |
| 2056 && (single_pred (b) == ENTRY_BLOCK_PTR | |
| 2057 || !JUMP_P (BB_END (single_pred (b))) | |
| 2058 || ! label_is_jump_target_p (BB_HEAD (b), | |
| 2059 BB_END (single_pred (b))))) | |
| 2060 { | |
| 2061 rtx label = BB_HEAD (b); | |
| 2062 | |
| 2063 delete_insn_chain (label, label, false); | |
| 2064 /* If the case label is undeletable, move it after the | |
| 2065 BASIC_BLOCK note. */ | |
| 2066 if (NOTE_KIND (BB_HEAD (b)) == NOTE_INSN_DELETED_LABEL) | |
| 2067 { | |
| 2068 rtx bb_note = NEXT_INSN (BB_HEAD (b)); | |
| 2069 | |
| 2070 reorder_insns_nobb (label, label, bb_note); | |
| 2071 BB_HEAD (b) = bb_note; | |
| 2072 if (BB_END (b) == bb_note) | |
| 2073 BB_END (b) = label; | |
| 2074 } | |
| 2075 if (dump_file) | |
| 2076 fprintf (dump_file, "Deleted label in block %i.\n", | |
| 2077 b->index); | |
| 2078 } | |
| 2079 | |
| 2080 /* If we fall through an empty block, we can remove it. */ | |
| 2081 if (!(mode & CLEANUP_CFGLAYOUT) | |
| 2082 && single_pred_p (b) | |
| 2083 && (single_pred_edge (b)->flags & EDGE_FALLTHRU) | |
| 2084 && !LABEL_P (BB_HEAD (b)) | |
| 2085 && FORWARDER_BLOCK_P (b) | |
| 2086 /* Note that forwarder_block_p true ensures that | |
| 2087 there is a successor for this block. */ | |
| 2088 && (single_succ_edge (b)->flags & EDGE_FALLTHRU) | |
| 2089 && n_basic_blocks > NUM_FIXED_BLOCKS + 1) | |
| 2090 { | |
| 2091 if (dump_file) | |
| 2092 fprintf (dump_file, | |
| 2093 "Deleting fallthru block %i.\n", | |
| 2094 b->index); | |
| 2095 | |
| 2096 c = b->prev_bb == ENTRY_BLOCK_PTR ? b->next_bb : b->prev_bb; | |
| 2097 redirect_edge_succ_nodup (single_pred_edge (b), | |
| 2098 single_succ (b)); | |
| 2099 delete_basic_block (b); | |
| 2100 changed = true; | |
| 2101 b = c; | |
|
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2102 continue; |
| 0 | 2103 } |
| 2104 | |
| 2105 if (single_succ_p (b) | |
| 2106 && (s = single_succ_edge (b)) | |
| 2107 && !(s->flags & EDGE_COMPLEX) | |
| 2108 && (c = s->dest) != EXIT_BLOCK_PTR | |
| 2109 && single_pred_p (c) | |
| 2110 && b != c) | |
| 2111 { | |
| 2112 /* When not in cfg_layout mode use code aware of reordering | |
| 2113 INSN. This code possibly creates new basic blocks so it | |
| 2114 does not fit merge_blocks interface and is kept here in | |
| 2115 hope that it will become useless once more of compiler | |
| 2116 is transformed to use cfg_layout mode. */ | |
| 2117 | |
| 2118 if ((mode & CLEANUP_CFGLAYOUT) | |
| 2119 && can_merge_blocks_p (b, c)) | |
| 2120 { | |
| 2121 merge_blocks (b, c); | |
| 2122 update_forwarder_flag (b); | |
| 2123 changed_here = true; | |
| 2124 } | |
| 2125 else if (!(mode & CLEANUP_CFGLAYOUT) | |
| 2126 /* If the jump insn has side effects, | |
| 2127 we can't kill the edge. */ | |
| 2128 && (!JUMP_P (BB_END (b)) | |
| 2129 || (reload_completed | |
| 2130 ? simplejump_p (BB_END (b)) | |
| 2131 : (onlyjump_p (BB_END (b)) | |
| 2132 && !tablejump_p (BB_END (b), | |
| 2133 NULL, NULL)))) | |
| 2134 && (next = merge_blocks_move (s, b, c, mode))) | |
| 2135 { | |
| 2136 b = next; | |
| 2137 changed_here = true; | |
| 2138 } | |
| 2139 } | |
| 2140 | |
| 2141 /* Simplify branch over branch. */ | |
| 2142 if ((mode & CLEANUP_EXPENSIVE) | |
| 2143 && !(mode & CLEANUP_CFGLAYOUT) | |
| 2144 && try_simplify_condjump (b)) | |
| 2145 changed_here = true; | |
| 2146 | |
| 2147 /* If B has a single outgoing edge, but uses a | |
| 2148 non-trivial jump instruction without side-effects, we | |
| 2149 can either delete the jump entirely, or replace it | |
| 2150 with a simple unconditional jump. */ | |
| 2151 if (single_succ_p (b) | |
| 2152 && single_succ (b) != EXIT_BLOCK_PTR | |
| 2153 && onlyjump_p (BB_END (b)) | |
| 2154 && !find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX) | |
| 2155 && try_redirect_by_replacing_jump (single_succ_edge (b), | |
| 2156 single_succ (b), | |
| 2157 (mode & CLEANUP_CFGLAYOUT) != 0)) | |
| 2158 { | |
| 2159 update_forwarder_flag (b); | |
| 2160 changed_here = true; | |
| 2161 } | |
| 2162 | |
| 2163 /* Simplify branch to branch. */ | |
| 2164 if (try_forward_edges (mode, b)) | |
| 2165 changed_here = true; | |
| 2166 | |
| 2167 /* Look for shared code between blocks. */ | |
| 2168 if ((mode & CLEANUP_CROSSJUMP) | |
| 2169 && try_crossjump_bb (mode, b)) | |
| 2170 changed_here = true; | |
| 2171 | |
| 2172 /* Don't get confused by the index shift caused by | |
| 2173 deleting blocks. */ | |
| 2174 if (!changed_here) | |
| 2175 b = b->next_bb; | |
| 2176 else | |
| 2177 changed = true; | |
| 2178 } | |
| 2179 | |
| 2180 if ((mode & CLEANUP_CROSSJUMP) | |
| 2181 && try_crossjump_bb (mode, EXIT_BLOCK_PTR)) | |
| 2182 changed = true; | |
| 2183 | |
| 2184 #ifdef ENABLE_CHECKING | |
| 2185 if (changed) | |
| 2186 verify_flow_info (); | |
| 2187 #endif | |
| 2188 | |
| 2189 changed_overall |= changed; | |
| 2190 first_pass = false; | |
| 2191 } | |
| 2192 while (changed); | |
| 2193 } | |
| 2194 | |
| 2195 FOR_ALL_BB (b) | |
| 2196 b->flags &= ~(BB_FORWARDER_BLOCK | BB_NONTHREADABLE_BLOCK); | |
| 2197 | |
| 2198 return changed_overall; | |
| 2199 } | |
| 2200 | |
| 2201 /* Delete all unreachable basic blocks. */ | |
| 2202 | |
| 2203 bool | |
| 2204 delete_unreachable_blocks (void) | |
| 2205 { | |
| 2206 bool changed = false; | |
|
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2207 basic_block b, prev_bb; |
| 0 | 2208 |
| 2209 find_unreachable_blocks (); | |
| 2210 | |
|
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2211 /* When we're in GIMPLE mode and there may be debug insns, we should |
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2212 delete blocks in reverse dominator order, so as to get a chance |
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2213 to substitute all released DEFs into debug stmts. If we don't |
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2214 have dominators information, walking blocks backward gets us a |
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2215 better chance of retaining most debug information than |
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|
2216 otherwise. */ |
|
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2217 if (MAY_HAVE_DEBUG_STMTS && current_ir_type () == IR_GIMPLE |
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2218 && dom_info_available_p (CDI_DOMINATORS)) |
| 0 | 2219 { |
|
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2220 for (b = EXIT_BLOCK_PTR->prev_bb; b != ENTRY_BLOCK_PTR; b = prev_bb) |
|
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2221 { |
|
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2222 prev_bb = b->prev_bb; |
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2223 |
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2224 if (!(b->flags & BB_REACHABLE)) |
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2225 { |
|
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2226 /* Speed up the removal of blocks that don't dominate |
|
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2227 others. Walking backwards, this should be the common |
|
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2228 case. */ |
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2229 if (!first_dom_son (CDI_DOMINATORS, b)) |
|
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2230 delete_basic_block (b); |
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2231 else |
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2232 { |
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2233 VEC (basic_block, heap) *h |
|
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2234 = get_all_dominated_blocks (CDI_DOMINATORS, b); |
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2235 |
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|
2236 while (VEC_length (basic_block, h)) |
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2237 { |
|
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2238 b = VEC_pop (basic_block, h); |
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2239 |
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|
2240 prev_bb = b->prev_bb; |
| 0 | 2241 |
|
55
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2242 gcc_assert (!(b->flags & BB_REACHABLE)); |
|
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2243 |
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2244 delete_basic_block (b); |
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2245 } |
|
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2246 |
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|
2247 VEC_free (basic_block, heap, h); |
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2248 } |
|
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2249 |
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2250 changed = true; |
|
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2251 } |
|
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2252 } |
|
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2253 } |
|
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2254 else |
|
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|
2255 { |
|
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|
2256 for (b = EXIT_BLOCK_PTR->prev_bb; b != ENTRY_BLOCK_PTR; b = prev_bb) |
| 0 | 2257 { |
|
55
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|
2258 prev_bb = b->prev_bb; |
|
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|
2259 |
|
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|
2260 if (!(b->flags & BB_REACHABLE)) |
|
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|
2261 { |
|
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|
2262 delete_basic_block (b); |
|
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|
2263 changed = true; |
|
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|
2264 } |
| 0 | 2265 } |
| 2266 } | |
| 2267 | |
| 2268 if (changed) | |
| 2269 tidy_fallthru_edges (); | |
| 2270 return changed; | |
| 2271 } | |
| 2272 | |
| 2273 /* Delete any jump tables never referenced. We can't delete them at the | |
| 2274 time of removing tablejump insn as they are referenced by the preceding | |
| 2275 insns computing the destination, so we delay deleting and garbagecollect | |
| 2276 them once life information is computed. */ | |
| 2277 void | |
| 2278 delete_dead_jumptables (void) | |
| 2279 { | |
| 2280 basic_block bb; | |
| 2281 | |
| 2282 /* A dead jump table does not belong to any basic block. Scan insns | |
| 2283 between two adjacent basic blocks. */ | |
| 2284 FOR_EACH_BB (bb) | |
| 2285 { | |
| 2286 rtx insn, next; | |
| 2287 | |
| 2288 for (insn = NEXT_INSN (BB_END (bb)); | |
| 2289 insn && !NOTE_INSN_BASIC_BLOCK_P (insn); | |
| 2290 insn = next) | |
| 2291 { | |
| 2292 next = NEXT_INSN (insn); | |
| 2293 if (LABEL_P (insn) | |
| 2294 && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn) | |
|
55
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|
2295 && JUMP_TABLE_DATA_P (next)) |
| 0 | 2296 { |
| 2297 rtx label = insn, jump = next; | |
| 2298 | |
| 2299 if (dump_file) | |
| 2300 fprintf (dump_file, "Dead jumptable %i removed\n", | |
| 2301 INSN_UID (insn)); | |
| 2302 | |
| 2303 next = NEXT_INSN (next); | |
| 2304 delete_insn (jump); | |
| 2305 delete_insn (label); | |
| 2306 } | |
| 2307 } | |
| 2308 } | |
| 2309 } | |
| 2310 | |
| 2311 | |
| 2312 /* Tidy the CFG by deleting unreachable code and whatnot. */ | |
| 2313 | |
| 2314 bool | |
| 2315 cleanup_cfg (int mode) | |
| 2316 { | |
| 2317 bool changed = false; | |
| 2318 | |
| 2319 /* Set the cfglayout mode flag here. We could update all the callers | |
| 2320 but that is just inconvenient, especially given that we eventually | |
| 2321 want to have cfglayout mode as the default. */ | |
| 2322 if (current_ir_type () == IR_RTL_CFGLAYOUT) | |
| 2323 mode |= CLEANUP_CFGLAYOUT; | |
| 2324 | |
| 2325 timevar_push (TV_CLEANUP_CFG); | |
| 2326 if (delete_unreachable_blocks ()) | |
| 2327 { | |
| 2328 changed = true; | |
| 2329 /* We've possibly created trivially dead code. Cleanup it right | |
| 2330 now to introduce more opportunities for try_optimize_cfg. */ | |
| 2331 if (!(mode & (CLEANUP_NO_INSN_DEL)) | |
| 2332 && !reload_completed) | |
| 2333 delete_trivially_dead_insns (get_insns (), max_reg_num ()); | |
| 2334 } | |
| 2335 | |
| 2336 compact_blocks (); | |
| 2337 | |
| 2338 /* To tail-merge blocks ending in the same noreturn function (e.g. | |
| 2339 a call to abort) we have to insert fake edges to exit. Do this | |
| 2340 here once. The fake edges do not interfere with any other CFG | |
| 2341 cleanups. */ | |
| 2342 if (mode & CLEANUP_CROSSJUMP) | |
| 2343 add_noreturn_fake_exit_edges (); | |
| 2344 | |
| 2345 if (!dbg_cnt (cfg_cleanup)) | |
| 2346 return changed; | |
| 2347 | |
| 2348 while (try_optimize_cfg (mode)) | |
| 2349 { | |
| 2350 delete_unreachable_blocks (), changed = true; | |
| 2351 if (!(mode & CLEANUP_NO_INSN_DEL)) | |
| 2352 { | |
| 2353 /* Try to remove some trivially dead insns when doing an expensive | |
| 2354 cleanup. But delete_trivially_dead_insns doesn't work after | |
| 2355 reload (it only handles pseudos) and run_fast_dce is too costly | |
| 2356 to run in every iteration. | |
| 2357 | |
| 2358 For effective cross jumping, we really want to run a fast DCE to | |
| 2359 clean up any dead conditions, or they get in the way of performing | |
| 2360 useful tail merges. | |
| 2361 | |
| 2362 Other transformations in cleanup_cfg are not so sensitive to dead | |
| 2363 code, so delete_trivially_dead_insns or even doing nothing at all | |
| 2364 is good enough. */ | |
| 2365 if ((mode & CLEANUP_EXPENSIVE) && !reload_completed | |
| 2366 && !delete_trivially_dead_insns (get_insns (), max_reg_num ())) | |
| 2367 break; | |
| 2368 else if ((mode & CLEANUP_CROSSJUMP) | |
| 2369 && crossjumps_occured) | |
| 2370 run_fast_dce (); | |
| 2371 } | |
| 2372 else | |
| 2373 break; | |
| 2374 } | |
| 2375 | |
| 2376 if (mode & CLEANUP_CROSSJUMP) | |
| 2377 remove_fake_exit_edges (); | |
| 2378 | |
| 2379 /* Don't call delete_dead_jumptables in cfglayout mode, because | |
| 2380 that function assumes that jump tables are in the insns stream. | |
| 2381 But we also don't _have_ to delete dead jumptables in cfglayout | |
| 2382 mode because we shouldn't even be looking at things that are | |
| 2383 not in a basic block. Dead jumptables are cleaned up when | |
| 2384 going out of cfglayout mode. */ | |
| 2385 if (!(mode & CLEANUP_CFGLAYOUT)) | |
| 2386 delete_dead_jumptables (); | |
| 2387 | |
| 2388 timevar_pop (TV_CLEANUP_CFG); | |
| 2389 | |
| 2390 return changed; | |
| 2391 } | |
| 2392 | |
| 2393 static unsigned int | |
| 2394 rest_of_handle_jump (void) | |
| 2395 { | |
| 2396 if (crtl->tail_call_emit) | |
| 2397 fixup_tail_calls (); | |
| 2398 return 0; | |
| 2399 } | |
| 2400 | |
| 2401 struct rtl_opt_pass pass_jump = | |
| 2402 { | |
| 2403 { | |
| 2404 RTL_PASS, | |
| 2405 "sibling", /* name */ | |
| 2406 NULL, /* gate */ | |
| 2407 rest_of_handle_jump, /* execute */ | |
| 2408 NULL, /* sub */ | |
| 2409 NULL, /* next */ | |
| 2410 0, /* static_pass_number */ | |
| 2411 TV_JUMP, /* tv_id */ | |
| 2412 0, /* properties_required */ | |
| 2413 0, /* properties_provided */ | |
| 2414 0, /* properties_destroyed */ | |
| 2415 TODO_ggc_collect, /* todo_flags_start */ | |
| 2416 TODO_verify_flow, /* todo_flags_finish */ | |
| 2417 } | |
| 2418 }; | |
| 2419 | |
| 2420 | |
| 2421 static unsigned int | |
| 2422 rest_of_handle_jump2 (void) | |
| 2423 { | |
| 2424 delete_trivially_dead_insns (get_insns (), max_reg_num ()); | |
| 2425 if (dump_file) | |
| 2426 dump_flow_info (dump_file, dump_flags); | |
| 2427 cleanup_cfg ((optimize ? CLEANUP_EXPENSIVE : 0) | |
| 2428 | (flag_thread_jumps ? CLEANUP_THREADING : 0)); | |
| 2429 return 0; | |
| 2430 } | |
| 2431 | |
| 2432 | |
| 2433 struct rtl_opt_pass pass_jump2 = | |
| 2434 { | |
| 2435 { | |
| 2436 RTL_PASS, | |
| 2437 "jump", /* name */ | |
| 2438 NULL, /* gate */ | |
| 2439 rest_of_handle_jump2, /* execute */ | |
| 2440 NULL, /* sub */ | |
| 2441 NULL, /* next */ | |
| 2442 0, /* static_pass_number */ | |
| 2443 TV_JUMP, /* tv_id */ | |
| 2444 0, /* properties_required */ | |
| 2445 0, /* properties_provided */ | |
| 2446 0, /* properties_destroyed */ | |
| 2447 TODO_ggc_collect, /* todo_flags_start */ | |
| 2448 TODO_dump_func | TODO_verify_rtl_sharing,/* todo_flags_finish */ | |
| 2449 } | |
| 2450 }; | |
| 2451 | |
| 2452 |