1/* Control flow graph building code for GNU compiler. 2 Copyright (C) 1987-2020 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify it under 7the terms of the GNU General Public License as published by the Free 8Software Foundation; either version 3, or (at your option) any later 9version. 10 11GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12WARRANTY; without even the implied warranty of MERCHANTABILITY or 13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14for more details. 15 16You should have received a copy of the GNU General Public License 17along with GCC; see the file COPYING3. If not see 18<http://www.gnu.org/licenses/>. */ 19 20 21#include "config.h" 22#include "system.h" 23#include "coretypes.h" 24#include "backend.h" 25#include "rtl.h" 26#include "cfghooks.h" 27#include "memmodel.h" 28#include "emit-rtl.h" 29#include "cfgrtl.h" 30#include "cfganal.h" 31#include "cfgbuild.h" 32#include "except.h" 33#include "stmt.h" 34 35static void make_edges (basic_block, basic_block, int); 36static void make_label_edge (sbitmap, basic_block, rtx, int); 37static void find_bb_boundaries (basic_block); 38static void compute_outgoing_frequencies (basic_block); 39 40/* Return true if insn is something that should be contained inside basic 41 block. */ 42 43bool 44inside_basic_block_p (const rtx_insn *insn) 45{ 46 switch (GET_CODE (insn)) 47 { 48 case CODE_LABEL: 49 /* Avoid creating of basic block for jumptables. */ 50 return (NEXT_INSN (insn) == 0 51 || ! JUMP_TABLE_DATA_P (NEXT_INSN (insn))); 52 53 case JUMP_INSN: 54 case CALL_INSN: 55 case INSN: 56 case DEBUG_INSN: 57 return true; 58 59 case JUMP_TABLE_DATA: 60 case BARRIER: 61 case NOTE: 62 return false; 63 64 default: 65 gcc_unreachable (); 66 } 67} 68 69/* Return true if INSN may cause control flow transfer, so it should be last in 70 the basic block. */ 71 72bool 73control_flow_insn_p (const rtx_insn *insn) 74{ 75 switch (GET_CODE (insn)) 76 { 77 case NOTE: 78 case CODE_LABEL: 79 case DEBUG_INSN: 80 return false; 81 82 case JUMP_INSN: 83 return true; 84 85 case CALL_INSN: 86 /* Noreturn and sibling call instructions terminate the basic blocks 87 (but only if they happen unconditionally). */ 88 if ((SIBLING_CALL_P (insn) 89 || find_reg_note (insn, REG_NORETURN, 0)) 90 && GET_CODE (PATTERN (insn)) != COND_EXEC) 91 return true; 92 93 /* Call insn may return to the nonlocal goto handler. */ 94 if (can_nonlocal_goto (insn)) 95 return true; 96 break; 97 98 case INSN: 99 /* Treat trap instructions like noreturn calls (same provision). */ 100 if (GET_CODE (PATTERN (insn)) == TRAP_IF 101 && XEXP (PATTERN (insn), 0) == const1_rtx) 102 return true; 103 if (!cfun->can_throw_non_call_exceptions) 104 return false; 105 break; 106 107 case JUMP_TABLE_DATA: 108 case BARRIER: 109 /* It is nonsense to reach this when looking for the 110 end of basic block, but before dead code is eliminated 111 this may happen. */ 112 return false; 113 114 default: 115 gcc_unreachable (); 116 } 117 118 return can_throw_internal (insn); 119} 120 121 122/* Create an edge between two basic blocks. FLAGS are auxiliary information 123 about the edge that is accumulated between calls. */ 124 125/* Create an edge from a basic block to a label. */ 126 127static void 128make_label_edge (sbitmap edge_cache, basic_block src, rtx label, int flags) 129{ 130 gcc_assert (LABEL_P (label)); 131 132 /* If the label was never emitted, this insn is junk, but avoid a 133 crash trying to refer to BLOCK_FOR_INSN (label). This can happen 134 as a result of a syntax error and a diagnostic has already been 135 printed. */ 136 137 if (INSN_UID (label) == 0) 138 return; 139 140 cached_make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags); 141} 142 143/* Create the edges generated by INSN in REGION. */ 144 145void 146rtl_make_eh_edge (sbitmap edge_cache, basic_block src, rtx insn) 147{ 148 eh_landing_pad lp = get_eh_landing_pad_from_rtx (insn); 149 150 if (lp) 151 { 152 rtx_insn *label = lp->landing_pad; 153 154 /* During initial rtl generation, use the post_landing_pad. */ 155 if (label == NULL) 156 { 157 gcc_assert (lp->post_landing_pad); 158 label = label_rtx (lp->post_landing_pad); 159 } 160 161 make_label_edge (edge_cache, src, label, 162 EDGE_ABNORMAL | EDGE_EH 163 | (CALL_P (insn) ? EDGE_ABNORMAL_CALL : 0)); 164 } 165} 166 167/* States of basic block as seen by find_many_sub_basic_blocks. */ 168enum state { 169 /* Basic blocks created via split_block belong to this state. 170 make_edges will examine these basic blocks to see if we need to 171 create edges going out of them. */ 172 BLOCK_NEW = 0, 173 174 /* Basic blocks that do not need examining belong to this state. 175 These blocks will be left intact. In particular, make_edges will 176 not create edges going out of these basic blocks. */ 177 BLOCK_ORIGINAL, 178 179 /* Basic blocks that may need splitting (due to a label appearing in 180 the middle, etc) belong to this state. After splitting them, 181 make_edges will create edges going out of them as needed. */ 182 BLOCK_TO_SPLIT 183}; 184 185#define STATE(BB) (enum state) ((size_t) (BB)->aux) 186#define SET_STATE(BB, STATE) ((BB)->aux = (void *) (size_t) (STATE)) 187 188/* Used internally by purge_dead_tablejump_edges, ORed into state. */ 189#define BLOCK_USED_BY_TABLEJUMP 32 190#define FULL_STATE(BB) ((size_t) (BB)->aux) 191 192/* Identify the edges going out of basic blocks between MIN and MAX, 193 inclusive, that have their states set to BLOCK_NEW or 194 BLOCK_TO_SPLIT. 195 196 UPDATE_P should be nonzero if we are updating CFG and zero if we 197 are building CFG from scratch. */ 198 199static void 200make_edges (basic_block min, basic_block max, int update_p) 201{ 202 basic_block bb; 203 sbitmap edge_cache = NULL; 204 205 /* Heavy use of computed goto in machine-generated code can lead to 206 nearly fully-connected CFGs. In that case we spend a significant 207 amount of time searching the edge lists for duplicates. */ 208 if (!vec_safe_is_empty (forced_labels) 209 || cfun->cfg->max_jumptable_ents > 100) 210 edge_cache = sbitmap_alloc (last_basic_block_for_fn (cfun)); 211 212 /* By nature of the way these get numbered, ENTRY_BLOCK_PTR->next_bb block 213 is always the entry. */ 214 if (min == ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb) 215 make_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun), min, EDGE_FALLTHRU); 216 217 FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb) 218 { 219 rtx_insn *insn; 220 enum rtx_code code; 221 edge e; 222 edge_iterator ei; 223 224 if (STATE (bb) == BLOCK_ORIGINAL) 225 continue; 226 227 /* If we have an edge cache, cache edges going out of BB. */ 228 if (edge_cache) 229 { 230 bitmap_clear (edge_cache); 231 if (update_p) 232 { 233 FOR_EACH_EDGE (e, ei, bb->succs) 234 if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)) 235 bitmap_set_bit (edge_cache, e->dest->index); 236 } 237 } 238 239 if (LABEL_P (BB_HEAD (bb)) 240 && LABEL_ALT_ENTRY_P (BB_HEAD (bb))) 241 cached_make_edge (NULL, ENTRY_BLOCK_PTR_FOR_FN (cfun), bb, 0); 242 243 /* Examine the last instruction of the block, and discover the 244 ways we can leave the block. */ 245 246 insn = BB_END (bb); 247 code = GET_CODE (insn); 248 249 /* A branch. */ 250 if (code == JUMP_INSN) 251 { 252 rtx tmp; 253 rtx_jump_table_data *table; 254 255 /* Recognize a non-local goto as a branch outside the 256 current function. */ 257 if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX)) 258 ; 259 260 /* Recognize a tablejump and do the right thing. */ 261 else if (tablejump_p (insn, NULL, &table)) 262 { 263 rtvec vec = table->get_labels (); 264 int j; 265 266 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j) 267 make_label_edge (edge_cache, bb, 268 XEXP (RTVEC_ELT (vec, j), 0), 0); 269 270 /* Some targets (eg, ARM) emit a conditional jump that also 271 contains the out-of-range target. Scan for these and 272 add an edge if necessary. */ 273 if ((tmp = single_set (insn)) != NULL 274 && SET_DEST (tmp) == pc_rtx 275 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE 276 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF) 277 make_label_edge (edge_cache, bb, 278 label_ref_label (XEXP (SET_SRC (tmp), 2)), 0); 279 } 280 281 /* If this is a computed jump, then mark it as reaching 282 everything on the forced_labels list. */ 283 else if (computed_jump_p (insn)) 284 { 285 rtx_insn *insn; 286 unsigned int i; 287 FOR_EACH_VEC_SAFE_ELT (forced_labels, i, insn) 288 make_label_edge (edge_cache, bb, insn, EDGE_ABNORMAL); 289 } 290 291 /* Returns create an exit out. */ 292 else if (returnjump_p (insn)) 293 cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun), 0); 294 295 /* Recognize asm goto and do the right thing. */ 296 else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL) 297 { 298 int i, n = ASM_OPERANDS_LABEL_LENGTH (tmp); 299 for (i = 0; i < n; ++i) 300 make_label_edge (edge_cache, bb, 301 XEXP (ASM_OPERANDS_LABEL (tmp, i), 0), 0); 302 } 303 304 /* Otherwise, we have a plain conditional or unconditional jump. */ 305 else 306 { 307 gcc_assert (JUMP_LABEL (insn)); 308 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0); 309 } 310 } 311 312 /* If this is a sibling call insn, then this is in effect a combined call 313 and return, and so we need an edge to the exit block. No need to 314 worry about EH edges, since we wouldn't have created the sibling call 315 in the first place. */ 316 if (code == CALL_INSN && SIBLING_CALL_P (insn)) 317 cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun), 318 EDGE_SIBCALL | EDGE_ABNORMAL); 319 320 /* If this is a CALL_INSN, then mark it as reaching the active EH 321 handler for this CALL_INSN. If we're handling non-call 322 exceptions then any insn can reach any of the active handlers. 323 Also mark the CALL_INSN as reaching any nonlocal goto handler. */ 324 else if (code == CALL_INSN || cfun->can_throw_non_call_exceptions) 325 { 326 /* Add any appropriate EH edges. */ 327 rtl_make_eh_edge (edge_cache, bb, insn); 328 329 if (code == CALL_INSN) 330 { 331 if (can_nonlocal_goto (insn)) 332 { 333 /* ??? This could be made smarter: in some cases it's 334 possible to tell that certain calls will not do a 335 nonlocal goto. For example, if the nested functions 336 that do the nonlocal gotos do not have their addresses 337 taken, then only calls to those functions or to other 338 nested functions that use them could possibly do 339 nonlocal gotos. */ 340 for (rtx_insn_list *x = nonlocal_goto_handler_labels; 341 x; 342 x = x->next ()) 343 make_label_edge (edge_cache, bb, x->insn (), 344 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL); 345 } 346 347 if (flag_tm) 348 { 349 rtx note; 350 for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) 351 if (REG_NOTE_KIND (note) == REG_TM) 352 make_label_edge (edge_cache, bb, XEXP (note, 0), 353 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL); 354 } 355 } 356 } 357 358 /* Find out if we can drop through to the next block. */ 359 insn = NEXT_INSN (insn); 360 e = find_edge (bb, EXIT_BLOCK_PTR_FOR_FN (cfun)); 361 if (e && e->flags & EDGE_FALLTHRU) 362 insn = NULL; 363 364 while (insn 365 && NOTE_P (insn) 366 && NOTE_KIND (insn) != NOTE_INSN_BASIC_BLOCK) 367 insn = NEXT_INSN (insn); 368 369 if (!insn) 370 cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun), 371 EDGE_FALLTHRU); 372 else if (bb->next_bb != EXIT_BLOCK_PTR_FOR_FN (cfun)) 373 { 374 if (insn == BB_HEAD (bb->next_bb)) 375 cached_make_edge (edge_cache, bb, bb->next_bb, EDGE_FALLTHRU); 376 } 377 } 378 379 if (edge_cache) 380 sbitmap_free (edge_cache); 381} 382 383static void 384mark_tablejump_edge (rtx label) 385{ 386 basic_block bb; 387 388 gcc_assert (LABEL_P (label)); 389 /* See comment in make_label_edge. */ 390 if (INSN_UID (label) == 0) 391 return; 392 bb = BLOCK_FOR_INSN (label); 393 SET_STATE (bb, FULL_STATE (bb) | BLOCK_USED_BY_TABLEJUMP); 394} 395 396static void 397purge_dead_tablejump_edges (basic_block bb, rtx_jump_table_data *table) 398{ 399 rtx_insn *insn = BB_END (bb); 400 rtx tmp; 401 rtvec vec; 402 int j; 403 edge_iterator ei; 404 edge e; 405 406 vec = table->get_labels (); 407 408 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j) 409 mark_tablejump_edge (XEXP (RTVEC_ELT (vec, j), 0)); 410 411 /* Some targets (eg, ARM) emit a conditional jump that also 412 contains the out-of-range target. Scan for these and 413 add an edge if necessary. */ 414 if ((tmp = single_set (insn)) != NULL 415 && SET_DEST (tmp) == pc_rtx 416 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE 417 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF) 418 mark_tablejump_edge (label_ref_label (XEXP (SET_SRC (tmp), 2))); 419 420 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 421 { 422 if (FULL_STATE (e->dest) & BLOCK_USED_BY_TABLEJUMP) 423 SET_STATE (e->dest, FULL_STATE (e->dest) 424 & ~(size_t) BLOCK_USED_BY_TABLEJUMP); 425 else if (!(e->flags & (EDGE_ABNORMAL | EDGE_EH))) 426 { 427 remove_edge (e); 428 continue; 429 } 430 ei_next (&ei); 431 } 432} 433 434/* Scan basic block BB for possible BB boundaries inside the block 435 and create new basic blocks in the progress. */ 436 437static void 438find_bb_boundaries (basic_block bb) 439{ 440 basic_block orig_bb = bb; 441 rtx_insn *insn = BB_HEAD (bb); 442 rtx_insn *end = BB_END (bb), *x; 443 rtx_jump_table_data *table; 444 rtx_insn *flow_transfer_insn = NULL; 445 rtx_insn *debug_insn = NULL; 446 edge fallthru = NULL; 447 bool skip_purge; 448 bool seen_note_after_debug = false; 449 450 if (insn == end) 451 return; 452 453 if (DEBUG_INSN_P (insn) || DEBUG_INSN_P (end)) 454 { 455 /* Check whether, without debug insns, the insn==end test above 456 would have caused us to return immediately, and behave the 457 same way even with debug insns. If we don't do this, debug 458 insns could cause us to purge dead edges at different times, 459 which could in turn change the cfg and affect codegen 460 decisions in subtle but undesirable ways. */ 461 while (insn != end && DEBUG_INSN_P (insn)) 462 insn = NEXT_INSN (insn); 463 rtx_insn *e = end; 464 while (insn != e && DEBUG_INSN_P (e)) 465 e = PREV_INSN (e); 466 if (insn == e) 467 { 468 /* If there are debug insns after a single insn that is a 469 control flow insn in the block, we'd have left right 470 away, but we should clean up the debug insns after the 471 control flow insn, because they can't remain in the same 472 block. So, do the debug insn cleaning up, but then bail 473 out without purging dead edges as we would if the debug 474 insns hadn't been there. */ 475 if (e != end && !DEBUG_INSN_P (e) && control_flow_insn_p (e)) 476 { 477 skip_purge = true; 478 flow_transfer_insn = e; 479 goto clean_up_debug_after_control_flow; 480 } 481 return; 482 } 483 } 484 485 if (LABEL_P (insn)) 486 insn = NEXT_INSN (insn); 487 488 /* Scan insn chain and try to find new basic block boundaries. */ 489 while (1) 490 { 491 enum rtx_code code = GET_CODE (insn); 492 493 if (code == DEBUG_INSN) 494 { 495 if (flow_transfer_insn && !debug_insn) 496 { 497 debug_insn = insn; 498 seen_note_after_debug = false; 499 } 500 } 501 /* In case we've previously seen an insn that effects a control 502 flow transfer, split the block. */ 503 else if ((flow_transfer_insn || code == CODE_LABEL) 504 && inside_basic_block_p (insn)) 505 { 506 rtx_insn *prev = PREV_INSN (insn); 507 508 /* If the first non-debug inside_basic_block_p insn after a control 509 flow transfer is not a label, split the block before the debug 510 insn instead of before the non-debug insn, so that the debug 511 insns are not lost. */ 512 if (debug_insn && code != CODE_LABEL && code != BARRIER) 513 { 514 prev = PREV_INSN (debug_insn); 515 if (seen_note_after_debug) 516 { 517 /* Though, if there are NOTEs intermixed with DEBUG_INSNs, 518 move the NOTEs before the DEBUG_INSNs and split after 519 the last NOTE. */ 520 rtx_insn *first = NULL, *last = NULL; 521 for (x = debug_insn; x != insn; x = NEXT_INSN (x)) 522 { 523 if (NOTE_P (x)) 524 { 525 if (first == NULL) 526 first = x; 527 last = x; 528 } 529 else 530 { 531 gcc_assert (DEBUG_INSN_P (x)); 532 if (first) 533 { 534 reorder_insns_nobb (first, last, prev); 535 prev = last; 536 first = last = NULL; 537 } 538 } 539 } 540 if (first) 541 { 542 reorder_insns_nobb (first, last, prev); 543 prev = last; 544 } 545 } 546 } 547 fallthru = split_block (bb, prev); 548 if (flow_transfer_insn) 549 { 550 BB_END (bb) = flow_transfer_insn; 551 552 rtx_insn *next; 553 /* Clean up the bb field for the insns between the blocks. */ 554 for (x = NEXT_INSN (flow_transfer_insn); 555 x != BB_HEAD (fallthru->dest); 556 x = next) 557 { 558 next = NEXT_INSN (x); 559 /* Debug insns should not be in between basic blocks, 560 drop them on the floor. */ 561 if (DEBUG_INSN_P (x)) 562 delete_insn (x); 563 else if (!BARRIER_P (x)) 564 set_block_for_insn (x, NULL); 565 } 566 } 567 568 bb = fallthru->dest; 569 remove_edge (fallthru); 570 /* BB is unreachable at this point - we need to determine its profile 571 once edges are built. */ 572 bb->count = profile_count::uninitialized (); 573 flow_transfer_insn = NULL; 574 debug_insn = NULL; 575 if (code == CODE_LABEL && LABEL_ALT_ENTRY_P (insn)) 576 make_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun), bb, 0); 577 } 578 else if (code == BARRIER) 579 { 580 /* __builtin_unreachable () may cause a barrier to be emitted in 581 the middle of a BB. We need to split it in the same manner as 582 if the barrier were preceded by a control_flow_insn_p insn. */ 583 if (!flow_transfer_insn) 584 flow_transfer_insn = prev_nonnote_nondebug_insn_bb (insn); 585 debug_insn = NULL; 586 } 587 else if (debug_insn) 588 { 589 if (code == NOTE) 590 seen_note_after_debug = true; 591 else 592 /* Jump tables. */ 593 debug_insn = NULL; 594 } 595 596 if (control_flow_insn_p (insn)) 597 flow_transfer_insn = insn; 598 if (insn == end) 599 break; 600 insn = NEXT_INSN (insn); 601 } 602 603 /* In case expander replaced normal insn by sequence terminating by 604 return and barrier, or possibly other sequence not behaving like 605 ordinary jump, we need to take care and move basic block boundary. */ 606 if (flow_transfer_insn && flow_transfer_insn != end) 607 { 608 skip_purge = false; 609 610 clean_up_debug_after_control_flow: 611 BB_END (bb) = flow_transfer_insn; 612 613 /* Clean up the bb field for the insns that do not belong to BB. */ 614 rtx_insn *next; 615 for (x = NEXT_INSN (flow_transfer_insn); ; x = next) 616 { 617 next = NEXT_INSN (x); 618 /* Debug insns should not be in between basic blocks, 619 drop them on the floor. */ 620 if (DEBUG_INSN_P (x)) 621 delete_insn (x); 622 else if (!BARRIER_P (x)) 623 set_block_for_insn (x, NULL); 624 if (x == end) 625 break; 626 } 627 628 if (skip_purge) 629 return; 630 } 631 632 /* We've possibly replaced the conditional jump by conditional jump 633 followed by cleanup at fallthru edge, so the outgoing edges may 634 be dead. */ 635 purge_dead_edges (bb); 636 637 /* purge_dead_edges doesn't handle tablejump's, but if we have split the 638 basic block, we might need to kill some edges. */ 639 if (bb != orig_bb && tablejump_p (BB_END (bb), NULL, &table)) 640 purge_dead_tablejump_edges (bb, table); 641} 642 643/* Assume that frequency of basic block B is known. Compute frequencies 644 and probabilities of outgoing edges. */ 645 646static void 647compute_outgoing_frequencies (basic_block b) 648{ 649 edge e, f; 650 edge_iterator ei; 651 652 if (EDGE_COUNT (b->succs) == 2) 653 { 654 rtx note = find_reg_note (BB_END (b), REG_BR_PROB, NULL); 655 int probability; 656 657 if (note) 658 { 659 probability = XINT (note, 0); 660 e = BRANCH_EDGE (b); 661 e->probability 662 = profile_probability::from_reg_br_prob_note (probability); 663 f = FALLTHRU_EDGE (b); 664 f->probability = e->probability.invert (); 665 return; 666 } 667 else 668 { 669 guess_outgoing_edge_probabilities (b); 670 } 671 } 672 else if (single_succ_p (b)) 673 { 674 e = single_succ_edge (b); 675 e->probability = profile_probability::always (); 676 return; 677 } 678 else 679 { 680 /* We rely on BBs with more than two successors to have sane probabilities 681 and do not guess them here. For BBs terminated by switch statements 682 expanded to jump-table jump, we have done the right thing during 683 expansion. For EH edges, we still guess the probabilities here. */ 684 bool complex_edge = false; 685 FOR_EACH_EDGE (e, ei, b->succs) 686 if (e->flags & EDGE_COMPLEX) 687 { 688 complex_edge = true; 689 break; 690 } 691 if (complex_edge) 692 guess_outgoing_edge_probabilities (b); 693 } 694} 695 696/* Assume that some pass has inserted labels or control flow 697 instructions within a basic block. Split basic blocks as needed 698 and create edges. */ 699 700void 701find_many_sub_basic_blocks (sbitmap blocks) 702{ 703 basic_block bb, min, max; 704 bool found = false; 705 auto_vec<unsigned int> n_succs; 706 n_succs.safe_grow_cleared (last_basic_block_for_fn (cfun)); 707 708 FOR_EACH_BB_FN (bb, cfun) 709 SET_STATE (bb, 710 bitmap_bit_p (blocks, bb->index) ? BLOCK_TO_SPLIT : BLOCK_ORIGINAL); 711 712 FOR_EACH_BB_FN (bb, cfun) 713 if (STATE (bb) == BLOCK_TO_SPLIT) 714 { 715 int n = last_basic_block_for_fn (cfun); 716 unsigned int ns = EDGE_COUNT (bb->succs); 717 718 find_bb_boundaries (bb); 719 if (n == last_basic_block_for_fn (cfun) && ns == EDGE_COUNT (bb->succs)) 720 n_succs[bb->index] = EDGE_COUNT (bb->succs); 721 } 722 723 FOR_EACH_BB_FN (bb, cfun) 724 if (STATE (bb) != BLOCK_ORIGINAL) 725 { 726 found = true; 727 break; 728 } 729 730 if (!found) 731 return; 732 733 min = max = bb; 734 for (; bb != EXIT_BLOCK_PTR_FOR_FN (cfun); bb = bb->next_bb) 735 if (STATE (bb) != BLOCK_ORIGINAL) 736 max = bb; 737 738 /* Now re-scan and wire in all edges. This expect simple (conditional) 739 jumps at the end of each new basic blocks. */ 740 make_edges (min, max, 1); 741 742 /* Update branch probabilities. Expect only (un)conditional jumps 743 to be created with only the forward edges. */ 744 if (profile_status_for_fn (cfun) != PROFILE_ABSENT) 745 FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb) 746 { 747 edge e; 748 edge_iterator ei; 749 750 if (STATE (bb) == BLOCK_ORIGINAL) 751 continue; 752 if (STATE (bb) == BLOCK_NEW) 753 { 754 bool initialized_src = false, uninitialized_src = false; 755 bb->count = profile_count::zero (); 756 FOR_EACH_EDGE (e, ei, bb->preds) 757 { 758 if (e->count ().initialized_p ()) 759 { 760 bb->count += e->count (); 761 initialized_src = true; 762 } 763 else 764 uninitialized_src = true; 765 } 766 /* When some edges are missing with read profile, this is 767 most likely because RTL expansion introduced loop. 768 When profile is guessed we may have BB that is reachable 769 from unlikely path as well as from normal path. 770 771 TODO: We should handle loops created during BB expansion 772 correctly here. For now we assume all those loop to cycle 773 precisely once. */ 774 if (!initialized_src 775 || (uninitialized_src 776 && profile_status_for_fn (cfun) < PROFILE_GUESSED)) 777 bb->count = profile_count::uninitialized (); 778 } 779 /* If nothing changed, there is no need to create new BBs. */ 780 else if (EDGE_COUNT (bb->succs) == n_succs[bb->index]) 781 { 782 /* In rare occassions RTL expansion might have mistakely assigned 783 a probabilities different from what is in CFG. This happens 784 when we try to split branch to two but optimize out the 785 second branch during the way. See PR81030. */ 786 if (JUMP_P (BB_END (bb)) && any_condjump_p (BB_END (bb)) 787 && EDGE_COUNT (bb->succs) >= 2) 788 update_br_prob_note (bb); 789 continue; 790 } 791 792 compute_outgoing_frequencies (bb); 793 } 794 795 FOR_EACH_BB_FN (bb, cfun) 796 SET_STATE (bb, 0); 797} 798