1 /* Control flow graph manipulation code for GNU compiler. 2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 4 2011, 2012 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 low level functions to manipulate the CFG and analyze it 23 that are aware of the RTL intermediate language. 24 25 Available functionality: 26 - Basic CFG/RTL manipulation API documented in cfghooks.h 27 - CFG-aware instruction chain manipulation 28 delete_insn, delete_insn_chain 29 - Edge splitting and committing to edges 30 insert_insn_on_edge, commit_edge_insertions 31 - CFG updating after insn simplification 32 purge_dead_edges, purge_all_dead_edges 33 - CFG fixing after coarse manipulation 34 fixup_abnormal_edges 35 36 Functions not supposed for generic use: 37 - Infrastructure to determine quickly basic block for insn 38 compute_bb_for_insn, update_bb_for_insn, set_block_for_insn, 39 - Edge redirection with updating and optimizing of insn chain 40 block_label, tidy_fallthru_edge, force_nonfallthru */ 41 42 #include "config.h" 43 #include "system.h" 44 #include "coretypes.h" 45 #include "tm.h" 46 #include "tree.h" 47 #include "hard-reg-set.h" 48 #include "basic-block.h" 49 #include "regs.h" 50 #include "flags.h" 51 #include "output.h" 52 #include "function.h" 53 #include "except.h" 54 #include "rtl-error.h" 55 #include "tm_p.h" 56 #include "obstack.h" 57 #include "insn-attr.h" 58 #include "insn-config.h" 59 #include "cfglayout.h" 60 #include "expr.h" 61 #include "target.h" 62 #include "common/common-target.h" 63 #include "cfgloop.h" 64 #include "ggc.h" 65 #include "tree-pass.h" 66 #include "df.h" 67 68 static int can_delete_note_p (const_rtx); 69 static int can_delete_label_p (const_rtx); 70 static basic_block rtl_split_edge (edge); 71 static bool rtl_move_block_after (basic_block, basic_block); 72 static int rtl_verify_flow_info (void); 73 static basic_block cfg_layout_split_block (basic_block, void *); 74 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block); 75 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block); 76 static void cfg_layout_delete_block (basic_block); 77 static void rtl_delete_block (basic_block); 78 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block); 79 static edge rtl_redirect_edge_and_branch (edge, basic_block); 80 static basic_block rtl_split_block (basic_block, void *); 81 static void rtl_dump_bb (basic_block, FILE *, int, int); 82 static int rtl_verify_flow_info_1 (void); 83 static void rtl_make_forwarder_block (edge); 84 85 /* Return true if NOTE is not one of the ones that must be kept paired, 86 so that we may simply delete it. */ 87 88 static int 89 can_delete_note_p (const_rtx note) 90 { 91 switch (NOTE_KIND (note)) 92 { 93 case NOTE_INSN_DELETED: 94 case NOTE_INSN_BASIC_BLOCK: 95 case NOTE_INSN_EPILOGUE_BEG: 96 return true; 97 98 default: 99 return false; 100 } 101 } 102 103 /* True if a given label can be deleted. */ 104 105 static int 106 can_delete_label_p (const_rtx label) 107 { 108 return (!LABEL_PRESERVE_P (label) 109 /* User declared labels must be preserved. */ 110 && LABEL_NAME (label) == 0 111 && !in_expr_list_p (forced_labels, label)); 112 } 113 114 /* Delete INSN by patching it out. Return the next insn. */ 115 116 rtx 117 delete_insn (rtx insn) 118 { 119 rtx next = NEXT_INSN (insn); 120 rtx note; 121 bool really_delete = true; 122 123 if (LABEL_P (insn)) 124 { 125 /* Some labels can't be directly removed from the INSN chain, as they 126 might be references via variables, constant pool etc. 127 Convert them to the special NOTE_INSN_DELETED_LABEL note. */ 128 if (! can_delete_label_p (insn)) 129 { 130 const char *name = LABEL_NAME (insn); 131 132 really_delete = false; 133 PUT_CODE (insn, NOTE); 134 NOTE_KIND (insn) = NOTE_INSN_DELETED_LABEL; 135 NOTE_DELETED_LABEL_NAME (insn) = name; 136 } 137 138 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels); 139 } 140 141 if (really_delete) 142 { 143 /* If this insn has already been deleted, something is very wrong. */ 144 gcc_assert (!INSN_DELETED_P (insn)); 145 remove_insn (insn); 146 INSN_DELETED_P (insn) = 1; 147 } 148 149 /* If deleting a jump, decrement the use count of the label. Deleting 150 the label itself should happen in the normal course of block merging. */ 151 if (JUMP_P (insn)) 152 { 153 if (JUMP_LABEL (insn) 154 && LABEL_P (JUMP_LABEL (insn))) 155 LABEL_NUSES (JUMP_LABEL (insn))--; 156 157 /* If there are more targets, remove them too. */ 158 while ((note 159 = find_reg_note (insn, REG_LABEL_TARGET, NULL_RTX)) != NULL_RTX 160 && LABEL_P (XEXP (note, 0))) 161 { 162 LABEL_NUSES (XEXP (note, 0))--; 163 remove_note (insn, note); 164 } 165 } 166 167 /* Also if deleting any insn that references a label as an operand. */ 168 while ((note = find_reg_note (insn, REG_LABEL_OPERAND, NULL_RTX)) != NULL_RTX 169 && LABEL_P (XEXP (note, 0))) 170 { 171 LABEL_NUSES (XEXP (note, 0))--; 172 remove_note (insn, note); 173 } 174 175 if (JUMP_TABLE_DATA_P (insn)) 176 { 177 rtx pat = PATTERN (insn); 178 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC; 179 int len = XVECLEN (pat, diff_vec_p); 180 int i; 181 182 for (i = 0; i < len; i++) 183 { 184 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0); 185 186 /* When deleting code in bulk (e.g. removing many unreachable 187 blocks) we can delete a label that's a target of the vector 188 before deleting the vector itself. */ 189 if (!NOTE_P (label)) 190 LABEL_NUSES (label)--; 191 } 192 } 193 194 return next; 195 } 196 197 /* Like delete_insn but also purge dead edges from BB. */ 198 199 rtx 200 delete_insn_and_edges (rtx insn) 201 { 202 rtx x; 203 bool purge = false; 204 205 if (INSN_P (insn) 206 && BLOCK_FOR_INSN (insn) 207 && BB_END (BLOCK_FOR_INSN (insn)) == insn) 208 purge = true; 209 x = delete_insn (insn); 210 if (purge) 211 purge_dead_edges (BLOCK_FOR_INSN (insn)); 212 return x; 213 } 214 215 /* Unlink a chain of insns between START and FINISH, leaving notes 216 that must be paired. If CLEAR_BB is true, we set bb field for 217 insns that cannot be removed to NULL. */ 218 219 void 220 delete_insn_chain (rtx start, rtx finish, bool clear_bb) 221 { 222 rtx next; 223 224 /* Unchain the insns one by one. It would be quicker to delete all of these 225 with a single unchaining, rather than one at a time, but we need to keep 226 the NOTE's. */ 227 while (1) 228 { 229 next = NEXT_INSN (start); 230 if (NOTE_P (start) && !can_delete_note_p (start)) 231 ; 232 else 233 next = delete_insn (start); 234 235 if (clear_bb && !INSN_DELETED_P (start)) 236 set_block_for_insn (start, NULL); 237 238 if (start == finish) 239 break; 240 start = next; 241 } 242 } 243 244 /* Create a new basic block consisting of the instructions between HEAD and END 245 inclusive. This function is designed to allow fast BB construction - reuses 246 the note and basic block struct in BB_NOTE, if any and do not grow 247 BASIC_BLOCK chain and should be used directly only by CFG construction code. 248 END can be NULL in to create new empty basic block before HEAD. Both END 249 and HEAD can be NULL to create basic block at the end of INSN chain. 250 AFTER is the basic block we should be put after. */ 251 252 basic_block 253 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after) 254 { 255 basic_block bb; 256 257 if (bb_note 258 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL 259 && bb->aux == NULL) 260 { 261 /* If we found an existing note, thread it back onto the chain. */ 262 263 rtx after; 264 265 if (LABEL_P (head)) 266 after = head; 267 else 268 { 269 after = PREV_INSN (head); 270 head = bb_note; 271 } 272 273 if (after != bb_note && NEXT_INSN (after) != bb_note) 274 reorder_insns_nobb (bb_note, bb_note, after); 275 } 276 else 277 { 278 /* Otherwise we must create a note and a basic block structure. */ 279 280 bb = alloc_block (); 281 282 init_rtl_bb_info (bb); 283 if (!head && !end) 284 head = end = bb_note 285 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ()); 286 else if (LABEL_P (head) && end) 287 { 288 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head); 289 if (head == end) 290 end = bb_note; 291 } 292 else 293 { 294 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head); 295 head = bb_note; 296 if (!end) 297 end = head; 298 } 299 300 NOTE_BASIC_BLOCK (bb_note) = bb; 301 } 302 303 /* Always include the bb note in the block. */ 304 if (NEXT_INSN (end) == bb_note) 305 end = bb_note; 306 307 BB_HEAD (bb) = head; 308 BB_END (bb) = end; 309 bb->index = last_basic_block++; 310 bb->flags = BB_NEW | BB_RTL; 311 link_block (bb, after); 312 SET_BASIC_BLOCK (bb->index, bb); 313 df_bb_refs_record (bb->index, false); 314 update_bb_for_insn (bb); 315 BB_SET_PARTITION (bb, BB_UNPARTITIONED); 316 317 /* Tag the block so that we know it has been used when considering 318 other basic block notes. */ 319 bb->aux = bb; 320 321 return bb; 322 } 323 324 /* Create new basic block consisting of instructions in between HEAD and END 325 and place it to the BB chain after block AFTER. END can be NULL to 326 create a new empty basic block before HEAD. Both END and HEAD can be 327 NULL to create basic block at the end of INSN chain. */ 328 329 static basic_block 330 rtl_create_basic_block (void *headp, void *endp, basic_block after) 331 { 332 rtx head = (rtx) headp, end = (rtx) endp; 333 basic_block bb; 334 335 /* Grow the basic block array if needed. */ 336 if ((size_t) last_basic_block >= VEC_length (basic_block, basic_block_info)) 337 { 338 size_t new_size = last_basic_block + (last_basic_block + 3) / 4; 339 VEC_safe_grow_cleared (basic_block, gc, basic_block_info, new_size); 340 } 341 342 n_basic_blocks++; 343 344 bb = create_basic_block_structure (head, end, NULL, after); 345 bb->aux = NULL; 346 return bb; 347 } 348 349 static basic_block 350 cfg_layout_create_basic_block (void *head, void *end, basic_block after) 351 { 352 basic_block newbb = rtl_create_basic_block (head, end, after); 353 354 return newbb; 355 } 356 357 /* Delete the insns in a (non-live) block. We physically delete every 358 non-deleted-note insn, and update the flow graph appropriately. 359 360 Return nonzero if we deleted an exception handler. */ 361 362 /* ??? Preserving all such notes strikes me as wrong. It would be nice 363 to post-process the stream to remove empty blocks, loops, ranges, etc. */ 364 365 static void 366 rtl_delete_block (basic_block b) 367 { 368 rtx insn, end; 369 370 /* If the head of this block is a CODE_LABEL, then it might be the 371 label for an exception handler which can't be reached. We need 372 to remove the label from the exception_handler_label list. */ 373 insn = BB_HEAD (b); 374 375 end = get_last_bb_insn (b); 376 377 /* Selectively delete the entire chain. */ 378 BB_HEAD (b) = NULL; 379 delete_insn_chain (insn, end, true); 380 381 382 if (dump_file) 383 fprintf (dump_file, "deleting block %d\n", b->index); 384 df_bb_delete (b->index); 385 } 386 387 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */ 388 389 void 390 compute_bb_for_insn (void) 391 { 392 basic_block bb; 393 394 FOR_EACH_BB (bb) 395 { 396 rtx end = BB_END (bb); 397 rtx insn; 398 399 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn)) 400 { 401 BLOCK_FOR_INSN (insn) = bb; 402 if (insn == end) 403 break; 404 } 405 } 406 } 407 408 /* Release the basic_block_for_insn array. */ 409 410 unsigned int 411 free_bb_for_insn (void) 412 { 413 rtx insn; 414 for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) 415 if (!BARRIER_P (insn)) 416 BLOCK_FOR_INSN (insn) = NULL; 417 return 0; 418 } 419 420 static unsigned int 421 rest_of_pass_free_cfg (void) 422 { 423 #ifdef DELAY_SLOTS 424 /* The resource.c machinery uses DF but the CFG isn't guaranteed to be 425 valid at that point so it would be too late to call df_analyze. */ 426 if (optimize > 0 && flag_delayed_branch) 427 { 428 df_note_add_problem (); 429 df_analyze (); 430 } 431 #endif 432 433 free_bb_for_insn (); 434 return 0; 435 } 436 437 struct rtl_opt_pass pass_free_cfg = 438 { 439 { 440 RTL_PASS, 441 "*free_cfg", /* name */ 442 NULL, /* gate */ 443 rest_of_pass_free_cfg, /* execute */ 444 NULL, /* sub */ 445 NULL, /* next */ 446 0, /* static_pass_number */ 447 TV_NONE, /* tv_id */ 448 0, /* properties_required */ 449 0, /* properties_provided */ 450 PROP_cfg, /* properties_destroyed */ 451 0, /* todo_flags_start */ 452 0, /* todo_flags_finish */ 453 } 454 }; 455 456 /* Return RTX to emit after when we want to emit code on the entry of function. */ 457 rtx 458 entry_of_function (void) 459 { 460 return (n_basic_blocks > NUM_FIXED_BLOCKS ? 461 BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ()); 462 } 463 464 /* Emit INSN at the entry point of the function, ensuring that it is only 465 executed once per function. */ 466 void 467 emit_insn_at_entry (rtx insn) 468 { 469 edge_iterator ei = ei_start (ENTRY_BLOCK_PTR->succs); 470 edge e = ei_safe_edge (ei); 471 gcc_assert (e->flags & EDGE_FALLTHRU); 472 473 insert_insn_on_edge (insn, e); 474 commit_edge_insertions (); 475 } 476 477 /* Update BLOCK_FOR_INSN of insns between BEGIN and END 478 (or BARRIER if found) and notify df of the bb change. 479 The insn chain range is inclusive 480 (i.e. both BEGIN and END will be updated. */ 481 482 static void 483 update_bb_for_insn_chain (rtx begin, rtx end, basic_block bb) 484 { 485 rtx insn; 486 487 end = NEXT_INSN (end); 488 for (insn = begin; insn != end; insn = NEXT_INSN (insn)) 489 if (!BARRIER_P (insn)) 490 df_insn_change_bb (insn, bb); 491 } 492 493 /* Update BLOCK_FOR_INSN of insns in BB to BB, 494 and notify df of the change. */ 495 496 void 497 update_bb_for_insn (basic_block bb) 498 { 499 update_bb_for_insn_chain (BB_HEAD (bb), BB_END (bb), bb); 500 } 501 502 503 /* Return the NOTE_INSN_BASIC_BLOCK of BB. */ 504 rtx 505 bb_note (basic_block bb) 506 { 507 rtx note; 508 509 note = BB_HEAD (bb); 510 if (LABEL_P (note)) 511 note = NEXT_INSN (note); 512 513 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (note)); 514 return note; 515 } 516 517 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK 518 note associated with the BLOCK. */ 519 520 static rtx 521 first_insn_after_basic_block_note (basic_block block) 522 { 523 rtx insn; 524 525 /* Get the first instruction in the block. */ 526 insn = BB_HEAD (block); 527 528 if (insn == NULL_RTX) 529 return NULL_RTX; 530 if (LABEL_P (insn)) 531 insn = NEXT_INSN (insn); 532 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn)); 533 534 return NEXT_INSN (insn); 535 } 536 537 /* Creates a new basic block just after basic block B by splitting 538 everything after specified instruction I. */ 539 540 static basic_block 541 rtl_split_block (basic_block bb, void *insnp) 542 { 543 basic_block new_bb; 544 rtx insn = (rtx) insnp; 545 edge e; 546 edge_iterator ei; 547 548 if (!insn) 549 { 550 insn = first_insn_after_basic_block_note (bb); 551 552 if (insn) 553 { 554 rtx next = insn; 555 556 insn = PREV_INSN (insn); 557 558 /* If the block contains only debug insns, insn would have 559 been NULL in a non-debug compilation, and then we'd end 560 up emitting a DELETED note. For -fcompare-debug 561 stability, emit the note too. */ 562 if (insn != BB_END (bb) 563 && DEBUG_INSN_P (next) 564 && DEBUG_INSN_P (BB_END (bb))) 565 { 566 while (next != BB_END (bb) && DEBUG_INSN_P (next)) 567 next = NEXT_INSN (next); 568 569 if (next == BB_END (bb)) 570 emit_note_after (NOTE_INSN_DELETED, next); 571 } 572 } 573 else 574 insn = get_last_insn (); 575 } 576 577 /* We probably should check type of the insn so that we do not create 578 inconsistent cfg. It is checked in verify_flow_info anyway, so do not 579 bother. */ 580 if (insn == BB_END (bb)) 581 emit_note_after (NOTE_INSN_DELETED, insn); 582 583 /* Create the new basic block. */ 584 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb); 585 BB_COPY_PARTITION (new_bb, bb); 586 BB_END (bb) = insn; 587 588 /* Redirect the outgoing edges. */ 589 new_bb->succs = bb->succs; 590 bb->succs = NULL; 591 FOR_EACH_EDGE (e, ei, new_bb->succs) 592 e->src = new_bb; 593 594 /* The new block starts off being dirty. */ 595 df_set_bb_dirty (bb); 596 return new_bb; 597 } 598 599 /* Blocks A and B are to be merged into a single block A. The insns 600 are already contiguous. */ 601 602 static void 603 rtl_merge_blocks (basic_block a, basic_block b) 604 { 605 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a); 606 rtx del_first = NULL_RTX, del_last = NULL_RTX; 607 rtx b_debug_start = b_end, b_debug_end = b_end; 608 bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0; 609 int b_empty = 0; 610 611 if (dump_file) 612 fprintf (dump_file, "Merging block %d into block %d...\n", b->index, 613 a->index); 614 615 while (DEBUG_INSN_P (b_end)) 616 b_end = PREV_INSN (b_debug_start = b_end); 617 618 /* If there was a CODE_LABEL beginning B, delete it. */ 619 if (LABEL_P (b_head)) 620 { 621 /* Detect basic blocks with nothing but a label. This can happen 622 in particular at the end of a function. */ 623 if (b_head == b_end) 624 b_empty = 1; 625 626 del_first = del_last = b_head; 627 b_head = NEXT_INSN (b_head); 628 } 629 630 /* Delete the basic block note and handle blocks containing just that 631 note. */ 632 if (NOTE_INSN_BASIC_BLOCK_P (b_head)) 633 { 634 if (b_head == b_end) 635 b_empty = 1; 636 if (! del_last) 637 del_first = b_head; 638 639 del_last = b_head; 640 b_head = NEXT_INSN (b_head); 641 } 642 643 /* If there was a jump out of A, delete it. */ 644 if (JUMP_P (a_end)) 645 { 646 rtx prev; 647 648 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev)) 649 if (!NOTE_P (prev) 650 || NOTE_INSN_BASIC_BLOCK_P (prev) 651 || prev == BB_HEAD (a)) 652 break; 653 654 del_first = a_end; 655 656 #ifdef HAVE_cc0 657 /* If this was a conditional jump, we need to also delete 658 the insn that set cc0. */ 659 if (only_sets_cc0_p (prev)) 660 { 661 rtx tmp = prev; 662 663 prev = prev_nonnote_insn (prev); 664 if (!prev) 665 prev = BB_HEAD (a); 666 del_first = tmp; 667 } 668 #endif 669 670 a_end = PREV_INSN (del_first); 671 } 672 else if (BARRIER_P (NEXT_INSN (a_end))) 673 del_first = NEXT_INSN (a_end); 674 675 /* Delete everything marked above as well as crap that might be 676 hanging out between the two blocks. */ 677 BB_HEAD (b) = NULL; 678 delete_insn_chain (del_first, del_last, true); 679 680 /* Reassociate the insns of B with A. */ 681 if (!b_empty) 682 { 683 update_bb_for_insn_chain (a_end, b_debug_end, a); 684 685 a_end = b_debug_end; 686 } 687 else if (b_end != b_debug_end) 688 { 689 /* Move any deleted labels and other notes between the end of A 690 and the debug insns that make up B after the debug insns, 691 bringing the debug insns into A while keeping the notes after 692 the end of A. */ 693 if (NEXT_INSN (a_end) != b_debug_start) 694 reorder_insns_nobb (NEXT_INSN (a_end), PREV_INSN (b_debug_start), 695 b_debug_end); 696 update_bb_for_insn_chain (b_debug_start, b_debug_end, a); 697 a_end = b_debug_end; 698 } 699 700 df_bb_delete (b->index); 701 BB_END (a) = a_end; 702 703 /* If B was a forwarder block, propagate the locus on the edge. */ 704 if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus) 705 EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus; 706 707 if (dump_file) 708 fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index); 709 } 710 711 712 /* Return true when block A and B can be merged. */ 713 714 static bool 715 rtl_can_merge_blocks (basic_block a, basic_block b) 716 { 717 /* If we are partitioning hot/cold basic blocks, we don't want to 718 mess up unconditional or indirect jumps that cross between hot 719 and cold sections. 720 721 Basic block partitioning may result in some jumps that appear to 722 be optimizable (or blocks that appear to be mergeable), but which really 723 must be left untouched (they are required to make it safely across 724 partition boundaries). See the comments at the top of 725 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ 726 727 if (BB_PARTITION (a) != BB_PARTITION (b)) 728 return false; 729 730 /* There must be exactly one edge in between the blocks. */ 731 return (single_succ_p (a) 732 && single_succ (a) == b 733 && single_pred_p (b) 734 && a != b 735 /* Must be simple edge. */ 736 && !(single_succ_edge (a)->flags & EDGE_COMPLEX) 737 && a->next_bb == b 738 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR 739 /* If the jump insn has side effects, 740 we can't kill the edge. */ 741 && (!JUMP_P (BB_END (a)) 742 || (reload_completed 743 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a))))); 744 } 745 746 /* Return the label in the head of basic block BLOCK. Create one if it doesn't 747 exist. */ 748 749 rtx 750 block_label (basic_block block) 751 { 752 if (block == EXIT_BLOCK_PTR) 753 return NULL_RTX; 754 755 if (!LABEL_P (BB_HEAD (block))) 756 { 757 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block)); 758 } 759 760 return BB_HEAD (block); 761 } 762 763 /* Attempt to perform edge redirection by replacing possibly complex jump 764 instruction by unconditional jump or removing jump completely. This can 765 apply only if all edges now point to the same block. The parameters and 766 return values are equivalent to redirect_edge_and_branch. */ 767 768 edge 769 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout) 770 { 771 basic_block src = e->src; 772 rtx insn = BB_END (src), kill_from; 773 rtx set; 774 int fallthru = 0; 775 776 /* If we are partitioning hot/cold basic blocks, we don't want to 777 mess up unconditional or indirect jumps that cross between hot 778 and cold sections. 779 780 Basic block partitioning may result in some jumps that appear to 781 be optimizable (or blocks that appear to be mergeable), but which really 782 must be left untouched (they are required to make it safely across 783 partition boundaries). See the comments at the top of 784 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ 785 786 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX) 787 || BB_PARTITION (src) != BB_PARTITION (target)) 788 return NULL; 789 790 /* We can replace or remove a complex jump only when we have exactly 791 two edges. Also, if we have exactly one outgoing edge, we can 792 redirect that. */ 793 if (EDGE_COUNT (src->succs) >= 3 794 /* Verify that all targets will be TARGET. Specifically, the 795 edge that is not E must also go to TARGET. */ 796 || (EDGE_COUNT (src->succs) == 2 797 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)) 798 return NULL; 799 800 if (!onlyjump_p (insn)) 801 return NULL; 802 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL)) 803 return NULL; 804 805 /* Avoid removing branch with side effects. */ 806 set = single_set (insn); 807 if (!set || side_effects_p (set)) 808 return NULL; 809 810 /* In case we zap a conditional jump, we'll need to kill 811 the cc0 setter too. */ 812 kill_from = insn; 813 #ifdef HAVE_cc0 814 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)) 815 && only_sets_cc0_p (PREV_INSN (insn))) 816 kill_from = PREV_INSN (insn); 817 #endif 818 819 /* See if we can create the fallthru edge. */ 820 if (in_cfglayout || can_fallthru (src, target)) 821 { 822 if (dump_file) 823 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn)); 824 fallthru = 1; 825 826 /* Selectively unlink whole insn chain. */ 827 if (in_cfglayout) 828 { 829 rtx insn = src->il.rtl->footer; 830 831 delete_insn_chain (kill_from, BB_END (src), false); 832 833 /* Remove barriers but keep jumptables. */ 834 while (insn) 835 { 836 if (BARRIER_P (insn)) 837 { 838 if (PREV_INSN (insn)) 839 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn); 840 else 841 src->il.rtl->footer = NEXT_INSN (insn); 842 if (NEXT_INSN (insn)) 843 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn); 844 } 845 if (LABEL_P (insn)) 846 break; 847 insn = NEXT_INSN (insn); 848 } 849 } 850 else 851 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)), 852 false); 853 } 854 855 /* If this already is simplejump, redirect it. */ 856 else if (simplejump_p (insn)) 857 { 858 if (e->dest == target) 859 return NULL; 860 if (dump_file) 861 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n", 862 INSN_UID (insn), e->dest->index, target->index); 863 if (!redirect_jump (insn, block_label (target), 0)) 864 { 865 gcc_assert (target == EXIT_BLOCK_PTR); 866 return NULL; 867 } 868 } 869 870 /* Cannot do anything for target exit block. */ 871 else if (target == EXIT_BLOCK_PTR) 872 return NULL; 873 874 /* Or replace possibly complicated jump insn by simple jump insn. */ 875 else 876 { 877 rtx target_label = block_label (target); 878 rtx barrier, label, table; 879 880 emit_jump_insn_after_noloc (gen_jump (target_label), insn); 881 JUMP_LABEL (BB_END (src)) = target_label; 882 LABEL_NUSES (target_label)++; 883 if (dump_file) 884 fprintf (dump_file, "Replacing insn %i by jump %i\n", 885 INSN_UID (insn), INSN_UID (BB_END (src))); 886 887 888 delete_insn_chain (kill_from, insn, false); 889 890 /* Recognize a tablejump that we are converting to a 891 simple jump and remove its associated CODE_LABEL 892 and ADDR_VEC or ADDR_DIFF_VEC. */ 893 if (tablejump_p (insn, &label, &table)) 894 delete_insn_chain (label, table, false); 895 896 barrier = next_nonnote_insn (BB_END (src)); 897 if (!barrier || !BARRIER_P (barrier)) 898 emit_barrier_after (BB_END (src)); 899 else 900 { 901 if (barrier != NEXT_INSN (BB_END (src))) 902 { 903 /* Move the jump before barrier so that the notes 904 which originally were or were created before jump table are 905 inside the basic block. */ 906 rtx new_insn = BB_END (src); 907 908 update_bb_for_insn_chain (NEXT_INSN (BB_END (src)), 909 PREV_INSN (barrier), src); 910 911 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn); 912 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn); 913 914 NEXT_INSN (new_insn) = barrier; 915 NEXT_INSN (PREV_INSN (barrier)) = new_insn; 916 917 PREV_INSN (new_insn) = PREV_INSN (barrier); 918 PREV_INSN (barrier) = new_insn; 919 } 920 } 921 } 922 923 /* Keep only one edge out and set proper flags. */ 924 if (!single_succ_p (src)) 925 remove_edge (e); 926 gcc_assert (single_succ_p (src)); 927 928 e = single_succ_edge (src); 929 if (fallthru) 930 e->flags = EDGE_FALLTHRU; 931 else 932 e->flags = 0; 933 934 e->probability = REG_BR_PROB_BASE; 935 e->count = src->count; 936 937 if (e->dest != target) 938 redirect_edge_succ (e, target); 939 return e; 940 } 941 942 /* Subroutine of redirect_branch_edge that tries to patch the jump 943 instruction INSN so that it reaches block NEW. Do this 944 only when it originally reached block OLD. Return true if this 945 worked or the original target wasn't OLD, return false if redirection 946 doesn't work. */ 947 948 static bool 949 patch_jump_insn (rtx insn, rtx old_label, basic_block new_bb) 950 { 951 rtx tmp; 952 /* Recognize a tablejump and adjust all matching cases. */ 953 if (tablejump_p (insn, NULL, &tmp)) 954 { 955 rtvec vec; 956 int j; 957 rtx new_label = block_label (new_bb); 958 959 if (new_bb == EXIT_BLOCK_PTR) 960 return false; 961 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC) 962 vec = XVEC (PATTERN (tmp), 0); 963 else 964 vec = XVEC (PATTERN (tmp), 1); 965 966 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j) 967 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label) 968 { 969 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label); 970 --LABEL_NUSES (old_label); 971 ++LABEL_NUSES (new_label); 972 } 973 974 /* Handle casesi dispatch insns. */ 975 if ((tmp = single_set (insn)) != NULL 976 && SET_DEST (tmp) == pc_rtx 977 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE 978 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF 979 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label) 980 { 981 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (Pmode, 982 new_label); 983 --LABEL_NUSES (old_label); 984 ++LABEL_NUSES (new_label); 985 } 986 } 987 else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL) 988 { 989 int i, n = ASM_OPERANDS_LABEL_LENGTH (tmp); 990 rtx new_label, note; 991 992 if (new_bb == EXIT_BLOCK_PTR) 993 return false; 994 new_label = block_label (new_bb); 995 996 for (i = 0; i < n; ++i) 997 { 998 rtx old_ref = ASM_OPERANDS_LABEL (tmp, i); 999 gcc_assert (GET_CODE (old_ref) == LABEL_REF); 1000 if (XEXP (old_ref, 0) == old_label) 1001 { 1002 ASM_OPERANDS_LABEL (tmp, i) 1003 = gen_rtx_LABEL_REF (Pmode, new_label); 1004 --LABEL_NUSES (old_label); 1005 ++LABEL_NUSES (new_label); 1006 } 1007 } 1008 1009 if (JUMP_LABEL (insn) == old_label) 1010 { 1011 JUMP_LABEL (insn) = new_label; 1012 note = find_reg_note (insn, REG_LABEL_TARGET, new_label); 1013 if (note) 1014 remove_note (insn, note); 1015 } 1016 else 1017 { 1018 note = find_reg_note (insn, REG_LABEL_TARGET, old_label); 1019 if (note) 1020 remove_note (insn, note); 1021 if (JUMP_LABEL (insn) != new_label 1022 && !find_reg_note (insn, REG_LABEL_TARGET, new_label)) 1023 add_reg_note (insn, REG_LABEL_TARGET, new_label); 1024 } 1025 while ((note = find_reg_note (insn, REG_LABEL_OPERAND, old_label)) 1026 != NULL_RTX) 1027 XEXP (note, 0) = new_label; 1028 } 1029 else 1030 { 1031 /* ?? We may play the games with moving the named labels from 1032 one basic block to the other in case only one computed_jump is 1033 available. */ 1034 if (computed_jump_p (insn) 1035 /* A return instruction can't be redirected. */ 1036 || returnjump_p (insn)) 1037 return false; 1038 1039 if (!currently_expanding_to_rtl || JUMP_LABEL (insn) == old_label) 1040 { 1041 /* If the insn doesn't go where we think, we're confused. */ 1042 gcc_assert (JUMP_LABEL (insn) == old_label); 1043 1044 /* If the substitution doesn't succeed, die. This can happen 1045 if the back end emitted unrecognizable instructions or if 1046 target is exit block on some arches. */ 1047 if (!redirect_jump (insn, block_label (new_bb), 0)) 1048 { 1049 gcc_assert (new_bb == EXIT_BLOCK_PTR); 1050 return false; 1051 } 1052 } 1053 } 1054 return true; 1055 } 1056 1057 1058 /* Redirect edge representing branch of (un)conditional jump or tablejump, 1059 NULL on failure */ 1060 static edge 1061 redirect_branch_edge (edge e, basic_block target) 1062 { 1063 rtx old_label = BB_HEAD (e->dest); 1064 basic_block src = e->src; 1065 rtx insn = BB_END (src); 1066 1067 /* We can only redirect non-fallthru edges of jump insn. */ 1068 if (e->flags & EDGE_FALLTHRU) 1069 return NULL; 1070 else if (!JUMP_P (insn) && !currently_expanding_to_rtl) 1071 return NULL; 1072 1073 if (!currently_expanding_to_rtl) 1074 { 1075 if (!patch_jump_insn (insn, old_label, target)) 1076 return NULL; 1077 } 1078 else 1079 /* When expanding this BB might actually contain multiple 1080 jumps (i.e. not yet split by find_many_sub_basic_blocks). 1081 Redirect all of those that match our label. */ 1082 FOR_BB_INSNS (src, insn) 1083 if (JUMP_P (insn) && !patch_jump_insn (insn, old_label, target)) 1084 return NULL; 1085 1086 if (dump_file) 1087 fprintf (dump_file, "Edge %i->%i redirected to %i\n", 1088 e->src->index, e->dest->index, target->index); 1089 1090 if (e->dest != target) 1091 e = redirect_edge_succ_nodup (e, target); 1092 1093 return e; 1094 } 1095 1096 /* Attempt to change code to redirect edge E to TARGET. Don't do that on 1097 expense of adding new instructions or reordering basic blocks. 1098 1099 Function can be also called with edge destination equivalent to the TARGET. 1100 Then it should try the simplifications and do nothing if none is possible. 1101 1102 Return edge representing the branch if transformation succeeded. Return NULL 1103 on failure. 1104 We still return NULL in case E already destinated TARGET and we didn't 1105 managed to simplify instruction stream. */ 1106 1107 static edge 1108 rtl_redirect_edge_and_branch (edge e, basic_block target) 1109 { 1110 edge ret; 1111 basic_block src = e->src; 1112 1113 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) 1114 return NULL; 1115 1116 if (e->dest == target) 1117 return e; 1118 1119 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL) 1120 { 1121 df_set_bb_dirty (src); 1122 return ret; 1123 } 1124 1125 ret = redirect_branch_edge (e, target); 1126 if (!ret) 1127 return NULL; 1128 1129 df_set_bb_dirty (src); 1130 return ret; 1131 } 1132 1133 /* Like force_nonfallthru below, but additionally performs redirection 1134 Used by redirect_edge_and_branch_force. JUMP_LABEL is used only 1135 when redirecting to the EXIT_BLOCK, it is either ret_rtx or 1136 simple_return_rtx, indicating which kind of returnjump to create. 1137 It should be NULL otherwise. */ 1138 1139 basic_block 1140 force_nonfallthru_and_redirect (edge e, basic_block target, rtx jump_label) 1141 { 1142 basic_block jump_block, new_bb = NULL, src = e->src; 1143 rtx note; 1144 edge new_edge; 1145 int abnormal_edge_flags = 0; 1146 bool asm_goto_edge = false; 1147 int loc; 1148 1149 /* In the case the last instruction is conditional jump to the next 1150 instruction, first redirect the jump itself and then continue 1151 by creating a basic block afterwards to redirect fallthru edge. */ 1152 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR 1153 && any_condjump_p (BB_END (e->src)) 1154 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest)) 1155 { 1156 rtx note; 1157 edge b = unchecked_make_edge (e->src, target, 0); 1158 bool redirected; 1159 1160 redirected = redirect_jump (BB_END (e->src), block_label (target), 0); 1161 gcc_assert (redirected); 1162 1163 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX); 1164 if (note) 1165 { 1166 int prob = INTVAL (XEXP (note, 0)); 1167 1168 b->probability = prob; 1169 b->count = e->count * prob / REG_BR_PROB_BASE; 1170 e->probability -= e->probability; 1171 e->count -= b->count; 1172 if (e->probability < 0) 1173 e->probability = 0; 1174 if (e->count < 0) 1175 e->count = 0; 1176 } 1177 } 1178 1179 if (e->flags & EDGE_ABNORMAL) 1180 { 1181 /* Irritating special case - fallthru edge to the same block as abnormal 1182 edge. 1183 We can't redirect abnormal edge, but we still can split the fallthru 1184 one and create separate abnormal edge to original destination. 1185 This allows bb-reorder to make such edge non-fallthru. */ 1186 gcc_assert (e->dest == target); 1187 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU); 1188 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU; 1189 } 1190 else 1191 { 1192 gcc_assert (e->flags & EDGE_FALLTHRU); 1193 if (e->src == ENTRY_BLOCK_PTR) 1194 { 1195 /* We can't redirect the entry block. Create an empty block 1196 at the start of the function which we use to add the new 1197 jump. */ 1198 edge tmp; 1199 edge_iterator ei; 1200 bool found = false; 1201 1202 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR); 1203 1204 /* Change the existing edge's source to be the new block, and add 1205 a new edge from the entry block to the new block. */ 1206 e->src = bb; 1207 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); ) 1208 { 1209 if (tmp == e) 1210 { 1211 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index); 1212 found = true; 1213 break; 1214 } 1215 else 1216 ei_next (&ei); 1217 } 1218 1219 gcc_assert (found); 1220 1221 VEC_safe_push (edge, gc, bb->succs, e); 1222 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU); 1223 } 1224 } 1225 1226 /* If e->src ends with asm goto, see if any of the ASM_OPERANDS_LABELs 1227 don't point to the target or fallthru label. */ 1228 if (JUMP_P (BB_END (e->src)) 1229 && target != EXIT_BLOCK_PTR 1230 && (e->flags & EDGE_FALLTHRU) 1231 && (note = extract_asm_operands (PATTERN (BB_END (e->src))))) 1232 { 1233 int i, n = ASM_OPERANDS_LABEL_LENGTH (note); 1234 1235 for (i = 0; i < n; ++i) 1236 { 1237 if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (e->dest)) 1238 XEXP (ASM_OPERANDS_LABEL (note, i), 0) = block_label (target); 1239 if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (target)) 1240 asm_goto_edge = true; 1241 } 1242 } 1243 1244 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags || asm_goto_edge) 1245 { 1246 gcov_type count = e->count; 1247 int probability = e->probability; 1248 /* Create the new structures. */ 1249 1250 /* If the old block ended with a tablejump, skip its table 1251 by searching forward from there. Otherwise start searching 1252 forward from the last instruction of the old block. */ 1253 if (!tablejump_p (BB_END (e->src), NULL, ¬e)) 1254 note = BB_END (e->src); 1255 note = NEXT_INSN (note); 1256 1257 jump_block = create_basic_block (note, NULL, e->src); 1258 jump_block->count = count; 1259 jump_block->frequency = EDGE_FREQUENCY (e); 1260 jump_block->loop_depth = target->loop_depth; 1261 1262 /* Make sure new block ends up in correct hot/cold section. */ 1263 1264 BB_COPY_PARTITION (jump_block, e->src); 1265 if (flag_reorder_blocks_and_partition 1266 && targetm_common.have_named_sections 1267 && JUMP_P (BB_END (jump_block)) 1268 && !any_condjump_p (BB_END (jump_block)) 1269 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING)) 1270 add_reg_note (BB_END (jump_block), REG_CROSSING_JUMP, NULL_RTX); 1271 1272 /* Wire edge in. */ 1273 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU); 1274 new_edge->probability = probability; 1275 new_edge->count = count; 1276 1277 /* Redirect old edge. */ 1278 redirect_edge_pred (e, jump_block); 1279 e->probability = REG_BR_PROB_BASE; 1280 1281 /* If asm goto has any label refs to target's label, 1282 add also edge from asm goto bb to target. */ 1283 if (asm_goto_edge) 1284 { 1285 new_edge->probability /= 2; 1286 new_edge->count /= 2; 1287 jump_block->count /= 2; 1288 jump_block->frequency /= 2; 1289 new_edge = make_edge (new_edge->src, target, 1290 e->flags & ~EDGE_FALLTHRU); 1291 new_edge->probability = probability - probability / 2; 1292 new_edge->count = count - count / 2; 1293 } 1294 1295 new_bb = jump_block; 1296 } 1297 else 1298 jump_block = e->src; 1299 1300 if (e->goto_locus && e->goto_block == NULL) 1301 loc = e->goto_locus; 1302 else 1303 loc = 0; 1304 e->flags &= ~EDGE_FALLTHRU; 1305 if (target == EXIT_BLOCK_PTR) 1306 { 1307 if (jump_label == ret_rtx) 1308 { 1309 #ifdef HAVE_return 1310 emit_jump_insn_after_setloc (gen_return (), BB_END (jump_block), loc); 1311 #else 1312 gcc_unreachable (); 1313 #endif 1314 } 1315 else 1316 { 1317 gcc_assert (jump_label == simple_return_rtx); 1318 #ifdef HAVE_simple_return 1319 emit_jump_insn_after_setloc (gen_simple_return (), 1320 BB_END (jump_block), loc); 1321 #else 1322 gcc_unreachable (); 1323 #endif 1324 } 1325 set_return_jump_label (BB_END (jump_block)); 1326 } 1327 else 1328 { 1329 rtx label = block_label (target); 1330 emit_jump_insn_after_setloc (gen_jump (label), BB_END (jump_block), loc); 1331 JUMP_LABEL (BB_END (jump_block)) = label; 1332 LABEL_NUSES (label)++; 1333 } 1334 1335 emit_barrier_after (BB_END (jump_block)); 1336 redirect_edge_succ_nodup (e, target); 1337 1338 if (abnormal_edge_flags) 1339 make_edge (src, target, abnormal_edge_flags); 1340 1341 df_mark_solutions_dirty (); 1342 return new_bb; 1343 } 1344 1345 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction 1346 (and possibly create new basic block) to make edge non-fallthru. 1347 Return newly created BB or NULL if none. */ 1348 1349 static basic_block 1350 rtl_force_nonfallthru (edge e) 1351 { 1352 return force_nonfallthru_and_redirect (e, e->dest, NULL_RTX); 1353 } 1354 1355 /* Redirect edge even at the expense of creating new jump insn or 1356 basic block. Return new basic block if created, NULL otherwise. 1357 Conversion must be possible. */ 1358 1359 static basic_block 1360 rtl_redirect_edge_and_branch_force (edge e, basic_block target) 1361 { 1362 if (redirect_edge_and_branch (e, target) 1363 || e->dest == target) 1364 return NULL; 1365 1366 /* In case the edge redirection failed, try to force it to be non-fallthru 1367 and redirect newly created simplejump. */ 1368 df_set_bb_dirty (e->src); 1369 return force_nonfallthru_and_redirect (e, target, NULL_RTX); 1370 } 1371 1372 /* The given edge should potentially be a fallthru edge. If that is in 1373 fact true, delete the jump and barriers that are in the way. */ 1374 1375 static void 1376 rtl_tidy_fallthru_edge (edge e) 1377 { 1378 rtx q; 1379 basic_block b = e->src, c = b->next_bb; 1380 1381 /* ??? In a late-running flow pass, other folks may have deleted basic 1382 blocks by nopping out blocks, leaving multiple BARRIERs between here 1383 and the target label. They ought to be chastised and fixed. 1384 1385 We can also wind up with a sequence of undeletable labels between 1386 one block and the next. 1387 1388 So search through a sequence of barriers, labels, and notes for 1389 the head of block C and assert that we really do fall through. */ 1390 1391 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q)) 1392 if (INSN_P (q)) 1393 return; 1394 1395 /* Remove what will soon cease being the jump insn from the source block. 1396 If block B consisted only of this single jump, turn it into a deleted 1397 note. */ 1398 q = BB_END (b); 1399 if (JUMP_P (q) 1400 && onlyjump_p (q) 1401 && (any_uncondjump_p (q) 1402 || single_succ_p (b))) 1403 { 1404 #ifdef HAVE_cc0 1405 /* If this was a conditional jump, we need to also delete 1406 the insn that set cc0. */ 1407 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q))) 1408 q = PREV_INSN (q); 1409 #endif 1410 1411 q = PREV_INSN (q); 1412 } 1413 1414 /* Selectively unlink the sequence. */ 1415 if (q != PREV_INSN (BB_HEAD (c))) 1416 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)), false); 1417 1418 e->flags |= EDGE_FALLTHRU; 1419 } 1420 1421 /* Should move basic block BB after basic block AFTER. NIY. */ 1422 1423 static bool 1424 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED, 1425 basic_block after ATTRIBUTE_UNUSED) 1426 { 1427 return false; 1428 } 1429 1430 /* Split a (typically critical) edge. Return the new block. 1431 The edge must not be abnormal. 1432 1433 ??? The code generally expects to be called on critical edges. 1434 The case of a block ending in an unconditional jump to a 1435 block with multiple predecessors is not handled optimally. */ 1436 1437 static basic_block 1438 rtl_split_edge (edge edge_in) 1439 { 1440 basic_block bb; 1441 rtx before; 1442 1443 /* Abnormal edges cannot be split. */ 1444 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL)); 1445 1446 /* We are going to place the new block in front of edge destination. 1447 Avoid existence of fallthru predecessors. */ 1448 if ((edge_in->flags & EDGE_FALLTHRU) == 0) 1449 { 1450 edge e = find_fallthru_edge (edge_in->dest->preds); 1451 1452 if (e) 1453 force_nonfallthru (e); 1454 } 1455 1456 /* Create the basic block note. */ 1457 if (edge_in->dest != EXIT_BLOCK_PTR) 1458 before = BB_HEAD (edge_in->dest); 1459 else 1460 before = NULL_RTX; 1461 1462 /* If this is a fall through edge to the exit block, the blocks might be 1463 not adjacent, and the right place is after the source. */ 1464 if ((edge_in->flags & EDGE_FALLTHRU) && edge_in->dest == EXIT_BLOCK_PTR) 1465 { 1466 before = NEXT_INSN (BB_END (edge_in->src)); 1467 bb = create_basic_block (before, NULL, edge_in->src); 1468 BB_COPY_PARTITION (bb, edge_in->src); 1469 } 1470 else 1471 { 1472 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb); 1473 /* ??? Why not edge_in->dest->prev_bb here? */ 1474 BB_COPY_PARTITION (bb, edge_in->dest); 1475 } 1476 1477 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU); 1478 1479 /* For non-fallthru edges, we must adjust the predecessor's 1480 jump instruction to target our new block. */ 1481 if ((edge_in->flags & EDGE_FALLTHRU) == 0) 1482 { 1483 edge redirected = redirect_edge_and_branch (edge_in, bb); 1484 gcc_assert (redirected); 1485 } 1486 else 1487 { 1488 if (edge_in->src != ENTRY_BLOCK_PTR) 1489 { 1490 /* For asm goto even splitting of fallthru edge might 1491 need insn patching, as other labels might point to the 1492 old label. */ 1493 rtx last = BB_END (edge_in->src); 1494 if (last 1495 && JUMP_P (last) 1496 && edge_in->dest != EXIT_BLOCK_PTR 1497 && extract_asm_operands (PATTERN (last)) != NULL_RTX 1498 && patch_jump_insn (last, before, bb)) 1499 df_set_bb_dirty (edge_in->src); 1500 } 1501 redirect_edge_succ (edge_in, bb); 1502 } 1503 1504 return bb; 1505 } 1506 1507 /* Queue instructions for insertion on an edge between two basic blocks. 1508 The new instructions and basic blocks (if any) will not appear in the 1509 CFG until commit_edge_insertions is called. */ 1510 1511 void 1512 insert_insn_on_edge (rtx pattern, edge e) 1513 { 1514 /* We cannot insert instructions on an abnormal critical edge. 1515 It will be easier to find the culprit if we die now. */ 1516 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e))); 1517 1518 if (e->insns.r == NULL_RTX) 1519 start_sequence (); 1520 else 1521 push_to_sequence (e->insns.r); 1522 1523 emit_insn (pattern); 1524 1525 e->insns.r = get_insns (); 1526 end_sequence (); 1527 } 1528 1529 /* Update the CFG for the instructions queued on edge E. */ 1530 1531 void 1532 commit_one_edge_insertion (edge e) 1533 { 1534 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last; 1535 basic_block bb; 1536 1537 /* Pull the insns off the edge now since the edge might go away. */ 1538 insns = e->insns.r; 1539 e->insns.r = NULL_RTX; 1540 1541 /* Figure out where to put these insns. If the destination has 1542 one predecessor, insert there. Except for the exit block. */ 1543 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR) 1544 { 1545 bb = e->dest; 1546 1547 /* Get the location correct wrt a code label, and "nice" wrt 1548 a basic block note, and before everything else. */ 1549 tmp = BB_HEAD (bb); 1550 if (LABEL_P (tmp)) 1551 tmp = NEXT_INSN (tmp); 1552 if (NOTE_INSN_BASIC_BLOCK_P (tmp)) 1553 tmp = NEXT_INSN (tmp); 1554 if (tmp == BB_HEAD (bb)) 1555 before = tmp; 1556 else if (tmp) 1557 after = PREV_INSN (tmp); 1558 else 1559 after = get_last_insn (); 1560 } 1561 1562 /* If the source has one successor and the edge is not abnormal, 1563 insert there. Except for the entry block. */ 1564 else if ((e->flags & EDGE_ABNORMAL) == 0 1565 && single_succ_p (e->src) 1566 && e->src != ENTRY_BLOCK_PTR) 1567 { 1568 bb = e->src; 1569 1570 /* It is possible to have a non-simple jump here. Consider a target 1571 where some forms of unconditional jumps clobber a register. This 1572 happens on the fr30 for example. 1573 1574 We know this block has a single successor, so we can just emit 1575 the queued insns before the jump. */ 1576 if (JUMP_P (BB_END (bb))) 1577 before = BB_END (bb); 1578 else 1579 { 1580 /* We'd better be fallthru, or we've lost track of what's what. */ 1581 gcc_assert (e->flags & EDGE_FALLTHRU); 1582 1583 after = BB_END (bb); 1584 } 1585 } 1586 1587 /* Otherwise we must split the edge. */ 1588 else 1589 { 1590 bb = split_edge (e); 1591 after = BB_END (bb); 1592 1593 if (flag_reorder_blocks_and_partition 1594 && targetm_common.have_named_sections 1595 && e->src != ENTRY_BLOCK_PTR 1596 && BB_PARTITION (e->src) == BB_COLD_PARTITION 1597 && !(e->flags & EDGE_CROSSING) 1598 && JUMP_P (after) 1599 && !any_condjump_p (after) 1600 && (single_succ_edge (bb)->flags & EDGE_CROSSING)) 1601 add_reg_note (after, REG_CROSSING_JUMP, NULL_RTX); 1602 } 1603 1604 /* Now that we've found the spot, do the insertion. */ 1605 if (before) 1606 { 1607 emit_insn_before_noloc (insns, before, bb); 1608 last = prev_nonnote_insn (before); 1609 } 1610 else 1611 last = emit_insn_after_noloc (insns, after, bb); 1612 1613 if (returnjump_p (last)) 1614 { 1615 /* ??? Remove all outgoing edges from BB and add one for EXIT. 1616 This is not currently a problem because this only happens 1617 for the (single) epilogue, which already has a fallthru edge 1618 to EXIT. */ 1619 1620 e = single_succ_edge (bb); 1621 gcc_assert (e->dest == EXIT_BLOCK_PTR 1622 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU)); 1623 1624 e->flags &= ~EDGE_FALLTHRU; 1625 emit_barrier_after (last); 1626 1627 if (before) 1628 delete_insn (before); 1629 } 1630 else 1631 gcc_assert (!JUMP_P (last)); 1632 } 1633 1634 /* Update the CFG for all queued instructions. */ 1635 1636 void 1637 commit_edge_insertions (void) 1638 { 1639 basic_block bb; 1640 1641 #ifdef ENABLE_CHECKING 1642 verify_flow_info (); 1643 #endif 1644 1645 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb) 1646 { 1647 edge e; 1648 edge_iterator ei; 1649 1650 FOR_EACH_EDGE (e, ei, bb->succs) 1651 if (e->insns.r) 1652 commit_one_edge_insertion (e); 1653 } 1654 } 1655 1656 1657 /* Print out RTL-specific basic block information (live information 1658 at start and end). */ 1659 1660 static void 1661 rtl_dump_bb (basic_block bb, FILE *outf, int indent, int flags ATTRIBUTE_UNUSED) 1662 { 1663 rtx insn; 1664 rtx last; 1665 char *s_indent; 1666 1667 s_indent = (char *) alloca ((size_t) indent + 1); 1668 memset (s_indent, ' ', (size_t) indent); 1669 s_indent[indent] = '\0'; 1670 1671 if (df) 1672 { 1673 df_dump_top (bb, outf); 1674 putc ('\n', outf); 1675 } 1676 1677 if (bb->index != ENTRY_BLOCK && bb->index != EXIT_BLOCK) 1678 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last; 1679 insn = NEXT_INSN (insn)) 1680 print_rtl_single (outf, insn); 1681 1682 if (df) 1683 { 1684 df_dump_bottom (bb, outf); 1685 putc ('\n', outf); 1686 } 1687 1688 } 1689 1690 /* Like print_rtl, but also print out live information for the start of each 1691 basic block. */ 1692 1693 void 1694 print_rtl_with_bb (FILE *outf, const_rtx rtx_first) 1695 { 1696 const_rtx tmp_rtx; 1697 if (rtx_first == 0) 1698 fprintf (outf, "(nil)\n"); 1699 else 1700 { 1701 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB }; 1702 int max_uid = get_max_uid (); 1703 basic_block *start = XCNEWVEC (basic_block, max_uid); 1704 basic_block *end = XCNEWVEC (basic_block, max_uid); 1705 enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid); 1706 1707 basic_block bb; 1708 1709 if (df) 1710 df_dump_start (outf); 1711 1712 FOR_EACH_BB_REVERSE (bb) 1713 { 1714 rtx x; 1715 1716 start[INSN_UID (BB_HEAD (bb))] = bb; 1717 end[INSN_UID (BB_END (bb))] = bb; 1718 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x)) 1719 { 1720 enum bb_state state = IN_MULTIPLE_BB; 1721 1722 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB) 1723 state = IN_ONE_BB; 1724 in_bb_p[INSN_UID (x)] = state; 1725 1726 if (x == BB_END (bb)) 1727 break; 1728 } 1729 } 1730 1731 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx)) 1732 { 1733 int did_output; 1734 1735 bb = start[INSN_UID (tmp_rtx)]; 1736 if (bb != NULL) 1737 dump_bb_info (bb, true, false, dump_flags, ";; ", outf); 1738 1739 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB 1740 && !NOTE_P (tmp_rtx) 1741 && !BARRIER_P (tmp_rtx)) 1742 fprintf (outf, ";; Insn is not within a basic block\n"); 1743 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB) 1744 fprintf (outf, ";; Insn is in multiple basic blocks\n"); 1745 1746 did_output = print_rtl_single (outf, tmp_rtx); 1747 1748 bb = end[INSN_UID (tmp_rtx)]; 1749 if (bb != NULL) 1750 dump_bb_info (bb, false, true, dump_flags, ";; ", outf); 1751 if (did_output) 1752 putc ('\n', outf); 1753 } 1754 1755 free (start); 1756 free (end); 1757 free (in_bb_p); 1758 } 1759 1760 if (crtl->epilogue_delay_list != 0) 1761 { 1762 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n"); 1763 for (tmp_rtx = crtl->epilogue_delay_list; tmp_rtx != 0; 1764 tmp_rtx = XEXP (tmp_rtx, 1)) 1765 print_rtl_single (outf, XEXP (tmp_rtx, 0)); 1766 } 1767 } 1768 1769 void 1770 update_br_prob_note (basic_block bb) 1771 { 1772 rtx note; 1773 if (!JUMP_P (BB_END (bb))) 1774 return; 1775 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX); 1776 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability) 1777 return; 1778 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability); 1779 } 1780 1781 /* Get the last insn associated with block BB (that includes barriers and 1782 tablejumps after BB). */ 1783 rtx 1784 get_last_bb_insn (basic_block bb) 1785 { 1786 rtx tmp; 1787 rtx end = BB_END (bb); 1788 1789 /* Include any jump table following the basic block. */ 1790 if (tablejump_p (end, NULL, &tmp)) 1791 end = tmp; 1792 1793 /* Include any barriers that may follow the basic block. */ 1794 tmp = next_nonnote_insn_bb (end); 1795 while (tmp && BARRIER_P (tmp)) 1796 { 1797 end = tmp; 1798 tmp = next_nonnote_insn_bb (end); 1799 } 1800 1801 return end; 1802 } 1803 1804 /* Verify the CFG and RTL consistency common for both underlying RTL and 1805 cfglayout RTL. 1806 1807 Currently it does following checks: 1808 1809 - overlapping of basic blocks 1810 - insns with wrong BLOCK_FOR_INSN pointers 1811 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note) 1812 - tails of basic blocks (ensure that boundary is necessary) 1813 - scans body of the basic block for JUMP_INSN, CODE_LABEL 1814 and NOTE_INSN_BASIC_BLOCK 1815 - verify that no fall_thru edge crosses hot/cold partition boundaries 1816 - verify that there are no pending RTL branch predictions 1817 1818 In future it can be extended check a lot of other stuff as well 1819 (reachability of basic blocks, life information, etc. etc.). */ 1820 1821 static int 1822 rtl_verify_flow_info_1 (void) 1823 { 1824 rtx x; 1825 int err = 0; 1826 basic_block bb; 1827 1828 /* Check the general integrity of the basic blocks. */ 1829 FOR_EACH_BB_REVERSE (bb) 1830 { 1831 rtx insn; 1832 1833 if (!(bb->flags & BB_RTL)) 1834 { 1835 error ("BB_RTL flag not set for block %d", bb->index); 1836 err = 1; 1837 } 1838 1839 FOR_BB_INSNS (bb, insn) 1840 if (BLOCK_FOR_INSN (insn) != bb) 1841 { 1842 error ("insn %d basic block pointer is %d, should be %d", 1843 INSN_UID (insn), 1844 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0, 1845 bb->index); 1846 err = 1; 1847 } 1848 1849 for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn)) 1850 if (!BARRIER_P (insn) 1851 && BLOCK_FOR_INSN (insn) != NULL) 1852 { 1853 error ("insn %d in header of bb %d has non-NULL basic block", 1854 INSN_UID (insn), bb->index); 1855 err = 1; 1856 } 1857 for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn)) 1858 if (!BARRIER_P (insn) 1859 && BLOCK_FOR_INSN (insn) != NULL) 1860 { 1861 error ("insn %d in footer of bb %d has non-NULL basic block", 1862 INSN_UID (insn), bb->index); 1863 err = 1; 1864 } 1865 } 1866 1867 /* Now check the basic blocks (boundaries etc.) */ 1868 FOR_EACH_BB_REVERSE (bb) 1869 { 1870 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0; 1871 edge e, fallthru = NULL; 1872 rtx note; 1873 edge_iterator ei; 1874 1875 if (JUMP_P (BB_END (bb)) 1876 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX)) 1877 && EDGE_COUNT (bb->succs) >= 2 1878 && any_condjump_p (BB_END (bb))) 1879 { 1880 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability 1881 && profile_status != PROFILE_ABSENT) 1882 { 1883 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i", 1884 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability); 1885 err = 1; 1886 } 1887 } 1888 FOR_EACH_EDGE (e, ei, bb->succs) 1889 { 1890 bool is_crossing; 1891 1892 if (e->flags & EDGE_FALLTHRU) 1893 n_fallthru++, fallthru = e; 1894 1895 is_crossing = (BB_PARTITION (e->src) != BB_PARTITION (e->dest) 1896 && e->src != ENTRY_BLOCK_PTR 1897 && e->dest != EXIT_BLOCK_PTR); 1898 if (e->flags & EDGE_CROSSING) 1899 { 1900 if (!is_crossing) 1901 { 1902 error ("EDGE_CROSSING incorrectly set across same section"); 1903 err = 1; 1904 } 1905 if (e->flags & EDGE_FALLTHRU) 1906 { 1907 error ("fallthru edge crosses section boundary (bb %i)", 1908 e->src->index); 1909 err = 1; 1910 } 1911 if (e->flags & EDGE_EH) 1912 { 1913 error ("EH edge crosses section boundary (bb %i)", 1914 e->src->index); 1915 err = 1; 1916 } 1917 } 1918 else if (is_crossing) 1919 { 1920 error ("EDGE_CROSSING missing across section boundary"); 1921 err = 1; 1922 } 1923 1924 if ((e->flags & ~(EDGE_DFS_BACK 1925 | EDGE_CAN_FALLTHRU 1926 | EDGE_IRREDUCIBLE_LOOP 1927 | EDGE_LOOP_EXIT 1928 | EDGE_CROSSING 1929 | EDGE_PRESERVE)) == 0) 1930 n_branch++; 1931 1932 if (e->flags & EDGE_ABNORMAL_CALL) 1933 n_call++; 1934 1935 if (e->flags & EDGE_EH) 1936 n_eh++; 1937 else if (e->flags & EDGE_ABNORMAL) 1938 n_abnormal++; 1939 } 1940 1941 if (n_eh && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX)) 1942 { 1943 error ("missing REG_EH_REGION note in the end of bb %i", bb->index); 1944 err = 1; 1945 } 1946 if (n_eh > 1) 1947 { 1948 error ("too many eh edges %i", bb->index); 1949 err = 1; 1950 } 1951 if (n_branch 1952 && (!JUMP_P (BB_END (bb)) 1953 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb)) 1954 || any_condjump_p (BB_END (bb)))))) 1955 { 1956 error ("too many outgoing branch edges from bb %i", bb->index); 1957 err = 1; 1958 } 1959 if (n_fallthru && any_uncondjump_p (BB_END (bb))) 1960 { 1961 error ("fallthru edge after unconditional jump %i", bb->index); 1962 err = 1; 1963 } 1964 if (n_branch != 1 && any_uncondjump_p (BB_END (bb))) 1965 { 1966 error ("wrong number of branch edges after unconditional jump %i", 1967 bb->index); 1968 err = 1; 1969 } 1970 if (n_branch != 1 && any_condjump_p (BB_END (bb)) 1971 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest)) 1972 { 1973 error ("wrong amount of branch edges after conditional jump %i", 1974 bb->index); 1975 err = 1; 1976 } 1977 if (n_call && !CALL_P (BB_END (bb))) 1978 { 1979 error ("call edges for non-call insn in bb %i", bb->index); 1980 err = 1; 1981 } 1982 if (n_abnormal 1983 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal) 1984 && (!JUMP_P (BB_END (bb)) 1985 || any_condjump_p (BB_END (bb)) 1986 || any_uncondjump_p (BB_END (bb)))) 1987 { 1988 error ("abnormal edges for no purpose in bb %i", bb->index); 1989 err = 1; 1990 } 1991 1992 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x)) 1993 /* We may have a barrier inside a basic block before dead code 1994 elimination. There is no BLOCK_FOR_INSN field in a barrier. */ 1995 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb) 1996 { 1997 debug_rtx (x); 1998 if (! BLOCK_FOR_INSN (x)) 1999 error 2000 ("insn %d inside basic block %d but block_for_insn is NULL", 2001 INSN_UID (x), bb->index); 2002 else 2003 error 2004 ("insn %d inside basic block %d but block_for_insn is %i", 2005 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index); 2006 2007 err = 1; 2008 } 2009 2010 /* OK pointers are correct. Now check the header of basic 2011 block. It ought to contain optional CODE_LABEL followed 2012 by NOTE_BASIC_BLOCK. */ 2013 x = BB_HEAD (bb); 2014 if (LABEL_P (x)) 2015 { 2016 if (BB_END (bb) == x) 2017 { 2018 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d", 2019 bb->index); 2020 err = 1; 2021 } 2022 2023 x = NEXT_INSN (x); 2024 } 2025 2026 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb) 2027 { 2028 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d", 2029 bb->index); 2030 err = 1; 2031 } 2032 2033 if (BB_END (bb) == x) 2034 /* Do checks for empty blocks here. */ 2035 ; 2036 else 2037 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x)) 2038 { 2039 if (NOTE_INSN_BASIC_BLOCK_P (x)) 2040 { 2041 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d", 2042 INSN_UID (x), bb->index); 2043 err = 1; 2044 } 2045 2046 if (x == BB_END (bb)) 2047 break; 2048 2049 if (control_flow_insn_p (x)) 2050 { 2051 error ("in basic block %d:", bb->index); 2052 fatal_insn ("flow control insn inside a basic block", x); 2053 } 2054 } 2055 } 2056 2057 /* Clean up. */ 2058 return err; 2059 } 2060 2061 /* Verify the CFG and RTL consistency common for both underlying RTL and 2062 cfglayout RTL. 2063 2064 Currently it does following checks: 2065 - all checks of rtl_verify_flow_info_1 2066 - test head/end pointers 2067 - check that all insns are in the basic blocks 2068 (except the switch handling code, barriers and notes) 2069 - check that all returns are followed by barriers 2070 - check that all fallthru edge points to the adjacent blocks. */ 2071 2072 static int 2073 rtl_verify_flow_info (void) 2074 { 2075 basic_block bb; 2076 int err = rtl_verify_flow_info_1 (); 2077 rtx x; 2078 rtx last_head = get_last_insn (); 2079 basic_block *bb_info; 2080 int num_bb_notes; 2081 const rtx rtx_first = get_insns (); 2082 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL; 2083 const int max_uid = get_max_uid (); 2084 2085 bb_info = XCNEWVEC (basic_block, max_uid); 2086 2087 FOR_EACH_BB_REVERSE (bb) 2088 { 2089 edge e; 2090 rtx head = BB_HEAD (bb); 2091 rtx end = BB_END (bb); 2092 2093 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x)) 2094 { 2095 /* Verify the end of the basic block is in the INSN chain. */ 2096 if (x == end) 2097 break; 2098 2099 /* And that the code outside of basic blocks has NULL bb field. */ 2100 if (!BARRIER_P (x) 2101 && BLOCK_FOR_INSN (x) != NULL) 2102 { 2103 error ("insn %d outside of basic blocks has non-NULL bb field", 2104 INSN_UID (x)); 2105 err = 1; 2106 } 2107 } 2108 2109 if (!x) 2110 { 2111 error ("end insn %d for block %d not found in the insn stream", 2112 INSN_UID (end), bb->index); 2113 err = 1; 2114 } 2115 2116 /* Work backwards from the end to the head of the basic block 2117 to verify the head is in the RTL chain. */ 2118 for (; x != NULL_RTX; x = PREV_INSN (x)) 2119 { 2120 /* While walking over the insn chain, verify insns appear 2121 in only one basic block. */ 2122 if (bb_info[INSN_UID (x)] != NULL) 2123 { 2124 error ("insn %d is in multiple basic blocks (%d and %d)", 2125 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index); 2126 err = 1; 2127 } 2128 2129 bb_info[INSN_UID (x)] = bb; 2130 2131 if (x == head) 2132 break; 2133 } 2134 if (!x) 2135 { 2136 error ("head insn %d for block %d not found in the insn stream", 2137 INSN_UID (head), bb->index); 2138 err = 1; 2139 } 2140 2141 last_head = PREV_INSN (x); 2142 2143 e = find_fallthru_edge (bb->succs); 2144 if (!e) 2145 { 2146 rtx insn; 2147 2148 /* Ensure existence of barrier in BB with no fallthru edges. */ 2149 for (insn = NEXT_INSN (BB_END (bb)); ; insn = NEXT_INSN (insn)) 2150 { 2151 if (!insn || NOTE_INSN_BASIC_BLOCK_P (insn)) 2152 { 2153 error ("missing barrier after block %i", bb->index); 2154 err = 1; 2155 break; 2156 } 2157 if (BARRIER_P (insn)) 2158 break; 2159 } 2160 } 2161 else if (e->src != ENTRY_BLOCK_PTR 2162 && e->dest != EXIT_BLOCK_PTR) 2163 { 2164 rtx insn; 2165 2166 if (e->src->next_bb != e->dest) 2167 { 2168 error 2169 ("verify_flow_info: Incorrect blocks for fallthru %i->%i", 2170 e->src->index, e->dest->index); 2171 err = 1; 2172 } 2173 else 2174 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest); 2175 insn = NEXT_INSN (insn)) 2176 if (BARRIER_P (insn) || INSN_P (insn)) 2177 { 2178 error ("verify_flow_info: Incorrect fallthru %i->%i", 2179 e->src->index, e->dest->index); 2180 fatal_insn ("wrong insn in the fallthru edge", insn); 2181 err = 1; 2182 } 2183 } 2184 } 2185 2186 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x)) 2187 { 2188 /* Check that the code before the first basic block has NULL 2189 bb field. */ 2190 if (!BARRIER_P (x) 2191 && BLOCK_FOR_INSN (x) != NULL) 2192 { 2193 error ("insn %d outside of basic blocks has non-NULL bb field", 2194 INSN_UID (x)); 2195 err = 1; 2196 } 2197 } 2198 free (bb_info); 2199 2200 num_bb_notes = 0; 2201 last_bb_seen = ENTRY_BLOCK_PTR; 2202 2203 for (x = rtx_first; x; x = NEXT_INSN (x)) 2204 { 2205 if (NOTE_INSN_BASIC_BLOCK_P (x)) 2206 { 2207 bb = NOTE_BASIC_BLOCK (x); 2208 2209 num_bb_notes++; 2210 if (bb != last_bb_seen->next_bb) 2211 internal_error ("basic blocks not laid down consecutively"); 2212 2213 curr_bb = last_bb_seen = bb; 2214 } 2215 2216 if (!curr_bb) 2217 { 2218 switch (GET_CODE (x)) 2219 { 2220 case BARRIER: 2221 case NOTE: 2222 break; 2223 2224 case CODE_LABEL: 2225 /* An addr_vec is placed outside any basic block. */ 2226 if (NEXT_INSN (x) 2227 && JUMP_TABLE_DATA_P (NEXT_INSN (x))) 2228 x = NEXT_INSN (x); 2229 2230 /* But in any case, non-deletable labels can appear anywhere. */ 2231 break; 2232 2233 default: 2234 fatal_insn ("insn outside basic block", x); 2235 } 2236 } 2237 2238 if (JUMP_P (x) 2239 && returnjump_p (x) && ! condjump_p (x) 2240 && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x)))) 2241 fatal_insn ("return not followed by barrier", x); 2242 if (curr_bb && x == BB_END (curr_bb)) 2243 curr_bb = NULL; 2244 } 2245 2246 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS) 2247 internal_error 2248 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)", 2249 num_bb_notes, n_basic_blocks); 2250 2251 return err; 2252 } 2253 2254 /* Assume that the preceding pass has possibly eliminated jump instructions 2255 or converted the unconditional jumps. Eliminate the edges from CFG. 2256 Return true if any edges are eliminated. */ 2257 2258 bool 2259 purge_dead_edges (basic_block bb) 2260 { 2261 edge e; 2262 rtx insn = BB_END (bb), note; 2263 bool purged = false; 2264 bool found; 2265 edge_iterator ei; 2266 2267 if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb)) 2268 do 2269 insn = PREV_INSN (insn); 2270 while ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb)); 2271 2272 /* If this instruction cannot trap, remove REG_EH_REGION notes. */ 2273 if (NONJUMP_INSN_P (insn) 2274 && (note = find_reg_note (insn, REG_EH_REGION, NULL))) 2275 { 2276 rtx eqnote; 2277 2278 if (! may_trap_p (PATTERN (insn)) 2279 || ((eqnote = find_reg_equal_equiv_note (insn)) 2280 && ! may_trap_p (XEXP (eqnote, 0)))) 2281 remove_note (insn, note); 2282 } 2283 2284 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */ 2285 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 2286 { 2287 bool remove = false; 2288 2289 /* There are three types of edges we need to handle correctly here: EH 2290 edges, abnormal call EH edges, and abnormal call non-EH edges. The 2291 latter can appear when nonlocal gotos are used. */ 2292 if (e->flags & EDGE_ABNORMAL_CALL) 2293 { 2294 if (!CALL_P (insn)) 2295 remove = true; 2296 else if (can_nonlocal_goto (insn)) 2297 ; 2298 else if ((e->flags & EDGE_EH) && can_throw_internal (insn)) 2299 ; 2300 else if (flag_tm && find_reg_note (insn, REG_TM, NULL)) 2301 ; 2302 else 2303 remove = true; 2304 } 2305 else if (e->flags & EDGE_EH) 2306 remove = !can_throw_internal (insn); 2307 2308 if (remove) 2309 { 2310 remove_edge (e); 2311 df_set_bb_dirty (bb); 2312 purged = true; 2313 } 2314 else 2315 ei_next (&ei); 2316 } 2317 2318 if (JUMP_P (insn)) 2319 { 2320 rtx note; 2321 edge b,f; 2322 edge_iterator ei; 2323 2324 /* We do care only about conditional jumps and simplejumps. */ 2325 if (!any_condjump_p (insn) 2326 && !returnjump_p (insn) 2327 && !simplejump_p (insn)) 2328 return purged; 2329 2330 /* Branch probability/prediction notes are defined only for 2331 condjumps. We've possibly turned condjump into simplejump. */ 2332 if (simplejump_p (insn)) 2333 { 2334 note = find_reg_note (insn, REG_BR_PROB, NULL); 2335 if (note) 2336 remove_note (insn, note); 2337 while ((note = find_reg_note (insn, REG_BR_PRED, NULL))) 2338 remove_note (insn, note); 2339 } 2340 2341 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 2342 { 2343 /* Avoid abnormal flags to leak from computed jumps turned 2344 into simplejumps. */ 2345 2346 e->flags &= ~EDGE_ABNORMAL; 2347 2348 /* See if this edge is one we should keep. */ 2349 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn)) 2350 /* A conditional jump can fall through into the next 2351 block, so we should keep the edge. */ 2352 { 2353 ei_next (&ei); 2354 continue; 2355 } 2356 else if (e->dest != EXIT_BLOCK_PTR 2357 && BB_HEAD (e->dest) == JUMP_LABEL (insn)) 2358 /* If the destination block is the target of the jump, 2359 keep the edge. */ 2360 { 2361 ei_next (&ei); 2362 continue; 2363 } 2364 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn)) 2365 /* If the destination block is the exit block, and this 2366 instruction is a return, then keep the edge. */ 2367 { 2368 ei_next (&ei); 2369 continue; 2370 } 2371 else if ((e->flags & EDGE_EH) && can_throw_internal (insn)) 2372 /* Keep the edges that correspond to exceptions thrown by 2373 this instruction and rematerialize the EDGE_ABNORMAL 2374 flag we just cleared above. */ 2375 { 2376 e->flags |= EDGE_ABNORMAL; 2377 ei_next (&ei); 2378 continue; 2379 } 2380 2381 /* We do not need this edge. */ 2382 df_set_bb_dirty (bb); 2383 purged = true; 2384 remove_edge (e); 2385 } 2386 2387 if (EDGE_COUNT (bb->succs) == 0 || !purged) 2388 return purged; 2389 2390 if (dump_file) 2391 fprintf (dump_file, "Purged edges from bb %i\n", bb->index); 2392 2393 if (!optimize) 2394 return purged; 2395 2396 /* Redistribute probabilities. */ 2397 if (single_succ_p (bb)) 2398 { 2399 single_succ_edge (bb)->probability = REG_BR_PROB_BASE; 2400 single_succ_edge (bb)->count = bb->count; 2401 } 2402 else 2403 { 2404 note = find_reg_note (insn, REG_BR_PROB, NULL); 2405 if (!note) 2406 return purged; 2407 2408 b = BRANCH_EDGE (bb); 2409 f = FALLTHRU_EDGE (bb); 2410 b->probability = INTVAL (XEXP (note, 0)); 2411 f->probability = REG_BR_PROB_BASE - b->probability; 2412 b->count = bb->count * b->probability / REG_BR_PROB_BASE; 2413 f->count = bb->count * f->probability / REG_BR_PROB_BASE; 2414 } 2415 2416 return purged; 2417 } 2418 else if (CALL_P (insn) && SIBLING_CALL_P (insn)) 2419 { 2420 /* First, there should not be any EH or ABCALL edges resulting 2421 from non-local gotos and the like. If there were, we shouldn't 2422 have created the sibcall in the first place. Second, there 2423 should of course never have been a fallthru edge. */ 2424 gcc_assert (single_succ_p (bb)); 2425 gcc_assert (single_succ_edge (bb)->flags 2426 == (EDGE_SIBCALL | EDGE_ABNORMAL)); 2427 2428 return 0; 2429 } 2430 2431 /* If we don't see a jump insn, we don't know exactly why the block would 2432 have been broken at this point. Look for a simple, non-fallthru edge, 2433 as these are only created by conditional branches. If we find such an 2434 edge we know that there used to be a jump here and can then safely 2435 remove all non-fallthru edges. */ 2436 found = false; 2437 FOR_EACH_EDGE (e, ei, bb->succs) 2438 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))) 2439 { 2440 found = true; 2441 break; 2442 } 2443 2444 if (!found) 2445 return purged; 2446 2447 /* Remove all but the fake and fallthru edges. The fake edge may be 2448 the only successor for this block in the case of noreturn 2449 calls. */ 2450 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 2451 { 2452 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE))) 2453 { 2454 df_set_bb_dirty (bb); 2455 remove_edge (e); 2456 purged = true; 2457 } 2458 else 2459 ei_next (&ei); 2460 } 2461 2462 gcc_assert (single_succ_p (bb)); 2463 2464 single_succ_edge (bb)->probability = REG_BR_PROB_BASE; 2465 single_succ_edge (bb)->count = bb->count; 2466 2467 if (dump_file) 2468 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n", 2469 bb->index); 2470 return purged; 2471 } 2472 2473 /* Search all basic blocks for potentially dead edges and purge them. Return 2474 true if some edge has been eliminated. */ 2475 2476 bool 2477 purge_all_dead_edges (void) 2478 { 2479 int purged = false; 2480 basic_block bb; 2481 2482 FOR_EACH_BB (bb) 2483 { 2484 bool purged_here = purge_dead_edges (bb); 2485 2486 purged |= purged_here; 2487 } 2488 2489 return purged; 2490 } 2491 2492 /* This is used by a few passes that emit some instructions after abnormal 2493 calls, moving the basic block's end, while they in fact do want to emit 2494 them on the fallthru edge. Look for abnormal call edges, find backward 2495 the call in the block and insert the instructions on the edge instead. 2496 2497 Similarly, handle instructions throwing exceptions internally. 2498 2499 Return true when instructions have been found and inserted on edges. */ 2500 2501 bool 2502 fixup_abnormal_edges (void) 2503 { 2504 bool inserted = false; 2505 basic_block bb; 2506 2507 FOR_EACH_BB (bb) 2508 { 2509 edge e; 2510 edge_iterator ei; 2511 2512 /* Look for cases we are interested in - calls or instructions causing 2513 exceptions. */ 2514 FOR_EACH_EDGE (e, ei, bb->succs) 2515 if ((e->flags & EDGE_ABNORMAL_CALL) 2516 || ((e->flags & (EDGE_ABNORMAL | EDGE_EH)) 2517 == (EDGE_ABNORMAL | EDGE_EH))) 2518 break; 2519 2520 if (e && !CALL_P (BB_END (bb)) && !can_throw_internal (BB_END (bb))) 2521 { 2522 rtx insn; 2523 2524 /* Get past the new insns generated. Allow notes, as the insns 2525 may be already deleted. */ 2526 insn = BB_END (bb); 2527 while ((NONJUMP_INSN_P (insn) || NOTE_P (insn)) 2528 && !can_throw_internal (insn) 2529 && insn != BB_HEAD (bb)) 2530 insn = PREV_INSN (insn); 2531 2532 if (CALL_P (insn) || can_throw_internal (insn)) 2533 { 2534 rtx stop, next; 2535 2536 e = find_fallthru_edge (bb->succs); 2537 2538 stop = NEXT_INSN (BB_END (bb)); 2539 BB_END (bb) = insn; 2540 2541 for (insn = NEXT_INSN (insn); insn != stop; insn = next) 2542 { 2543 next = NEXT_INSN (insn); 2544 if (INSN_P (insn)) 2545 { 2546 delete_insn (insn); 2547 2548 /* Sometimes there's still the return value USE. 2549 If it's placed after a trapping call (i.e. that 2550 call is the last insn anyway), we have no fallthru 2551 edge. Simply delete this use and don't try to insert 2552 on the non-existent edge. */ 2553 if (GET_CODE (PATTERN (insn)) != USE) 2554 { 2555 /* We're not deleting it, we're moving it. */ 2556 INSN_DELETED_P (insn) = 0; 2557 PREV_INSN (insn) = NULL_RTX; 2558 NEXT_INSN (insn) = NULL_RTX; 2559 2560 insert_insn_on_edge (insn, e); 2561 inserted = true; 2562 } 2563 } 2564 else if (!BARRIER_P (insn)) 2565 set_block_for_insn (insn, NULL); 2566 } 2567 } 2568 2569 /* It may be that we don't find any trapping insn. In this 2570 case we discovered quite late that the insn that had been 2571 marked as can_throw_internal in fact couldn't trap at all. 2572 So we should in fact delete the EH edges out of the block. */ 2573 else 2574 purge_dead_edges (bb); 2575 } 2576 } 2577 2578 return inserted; 2579 } 2580 2581 /* Same as split_block but update cfg_layout structures. */ 2582 2583 static basic_block 2584 cfg_layout_split_block (basic_block bb, void *insnp) 2585 { 2586 rtx insn = (rtx) insnp; 2587 basic_block new_bb = rtl_split_block (bb, insn); 2588 2589 new_bb->il.rtl->footer = bb->il.rtl->footer; 2590 bb->il.rtl->footer = NULL; 2591 2592 return new_bb; 2593 } 2594 2595 /* Redirect Edge to DEST. */ 2596 static edge 2597 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest) 2598 { 2599 basic_block src = e->src; 2600 edge ret; 2601 2602 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) 2603 return NULL; 2604 2605 if (e->dest == dest) 2606 return e; 2607 2608 if (e->src != ENTRY_BLOCK_PTR 2609 && (ret = try_redirect_by_replacing_jump (e, dest, true))) 2610 { 2611 df_set_bb_dirty (src); 2612 return ret; 2613 } 2614 2615 if (e->src == ENTRY_BLOCK_PTR 2616 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX)) 2617 { 2618 if (dump_file) 2619 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n", 2620 e->src->index, dest->index); 2621 2622 df_set_bb_dirty (e->src); 2623 redirect_edge_succ (e, dest); 2624 return e; 2625 } 2626 2627 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge 2628 in the case the basic block appears to be in sequence. Avoid this 2629 transformation. */ 2630 2631 if (e->flags & EDGE_FALLTHRU) 2632 { 2633 /* Redirect any branch edges unified with the fallthru one. */ 2634 if (JUMP_P (BB_END (src)) 2635 && label_is_jump_target_p (BB_HEAD (e->dest), 2636 BB_END (src))) 2637 { 2638 edge redirected; 2639 2640 if (dump_file) 2641 fprintf (dump_file, "Fallthru edge unified with branch " 2642 "%i->%i redirected to %i\n", 2643 e->src->index, e->dest->index, dest->index); 2644 e->flags &= ~EDGE_FALLTHRU; 2645 redirected = redirect_branch_edge (e, dest); 2646 gcc_assert (redirected); 2647 redirected->flags |= EDGE_FALLTHRU; 2648 df_set_bb_dirty (redirected->src); 2649 return redirected; 2650 } 2651 /* In case we are redirecting fallthru edge to the branch edge 2652 of conditional jump, remove it. */ 2653 if (EDGE_COUNT (src->succs) == 2) 2654 { 2655 /* Find the edge that is different from E. */ 2656 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e); 2657 2658 if (s->dest == dest 2659 && any_condjump_p (BB_END (src)) 2660 && onlyjump_p (BB_END (src))) 2661 delete_insn (BB_END (src)); 2662 } 2663 if (dump_file) 2664 fprintf (dump_file, "Redirecting fallthru edge %i->%i to %i\n", 2665 e->src->index, e->dest->index, dest->index); 2666 ret = redirect_edge_succ_nodup (e, dest); 2667 } 2668 else 2669 ret = redirect_branch_edge (e, dest); 2670 2671 /* We don't want simplejumps in the insn stream during cfglayout. */ 2672 gcc_assert (!simplejump_p (BB_END (src))); 2673 2674 df_set_bb_dirty (src); 2675 return ret; 2676 } 2677 2678 /* Simple wrapper as we always can redirect fallthru edges. */ 2679 static basic_block 2680 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest) 2681 { 2682 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest); 2683 2684 gcc_assert (redirected); 2685 return NULL; 2686 } 2687 2688 /* Same as delete_basic_block but update cfg_layout structures. */ 2689 2690 static void 2691 cfg_layout_delete_block (basic_block bb) 2692 { 2693 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints; 2694 2695 if (bb->il.rtl->header) 2696 { 2697 next = BB_HEAD (bb); 2698 if (prev) 2699 NEXT_INSN (prev) = bb->il.rtl->header; 2700 else 2701 set_first_insn (bb->il.rtl->header); 2702 PREV_INSN (bb->il.rtl->header) = prev; 2703 insn = bb->il.rtl->header; 2704 while (NEXT_INSN (insn)) 2705 insn = NEXT_INSN (insn); 2706 NEXT_INSN (insn) = next; 2707 PREV_INSN (next) = insn; 2708 } 2709 next = NEXT_INSN (BB_END (bb)); 2710 if (bb->il.rtl->footer) 2711 { 2712 insn = bb->il.rtl->footer; 2713 while (insn) 2714 { 2715 if (BARRIER_P (insn)) 2716 { 2717 if (PREV_INSN (insn)) 2718 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn); 2719 else 2720 bb->il.rtl->footer = NEXT_INSN (insn); 2721 if (NEXT_INSN (insn)) 2722 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn); 2723 } 2724 if (LABEL_P (insn)) 2725 break; 2726 insn = NEXT_INSN (insn); 2727 } 2728 if (bb->il.rtl->footer) 2729 { 2730 insn = BB_END (bb); 2731 NEXT_INSN (insn) = bb->il.rtl->footer; 2732 PREV_INSN (bb->il.rtl->footer) = insn; 2733 while (NEXT_INSN (insn)) 2734 insn = NEXT_INSN (insn); 2735 NEXT_INSN (insn) = next; 2736 if (next) 2737 PREV_INSN (next) = insn; 2738 else 2739 set_last_insn (insn); 2740 } 2741 } 2742 if (bb->next_bb != EXIT_BLOCK_PTR) 2743 to = &bb->next_bb->il.rtl->header; 2744 else 2745 to = &cfg_layout_function_footer; 2746 2747 rtl_delete_block (bb); 2748 2749 if (prev) 2750 prev = NEXT_INSN (prev); 2751 else 2752 prev = get_insns (); 2753 if (next) 2754 next = PREV_INSN (next); 2755 else 2756 next = get_last_insn (); 2757 2758 if (next && NEXT_INSN (next) != prev) 2759 { 2760 remaints = unlink_insn_chain (prev, next); 2761 insn = remaints; 2762 while (NEXT_INSN (insn)) 2763 insn = NEXT_INSN (insn); 2764 NEXT_INSN (insn) = *to; 2765 if (*to) 2766 PREV_INSN (*to) = insn; 2767 *to = remaints; 2768 } 2769 } 2770 2771 /* Return true when blocks A and B can be safely merged. */ 2772 2773 static bool 2774 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b) 2775 { 2776 /* If we are partitioning hot/cold basic blocks, we don't want to 2777 mess up unconditional or indirect jumps that cross between hot 2778 and cold sections. 2779 2780 Basic block partitioning may result in some jumps that appear to 2781 be optimizable (or blocks that appear to be mergeable), but which really 2782 must be left untouched (they are required to make it safely across 2783 partition boundaries). See the comments at the top of 2784 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ 2785 2786 if (BB_PARTITION (a) != BB_PARTITION (b)) 2787 return false; 2788 2789 /* If we would end up moving B's instructions, make sure it doesn't fall 2790 through into the exit block, since we cannot recover from a fallthrough 2791 edge into the exit block occurring in the middle of a function. */ 2792 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b)) 2793 { 2794 edge e = find_fallthru_edge (b->succs); 2795 if (e && e->dest == EXIT_BLOCK_PTR) 2796 return false; 2797 } 2798 2799 /* There must be exactly one edge in between the blocks. */ 2800 return (single_succ_p (a) 2801 && single_succ (a) == b 2802 && single_pred_p (b) == 1 2803 && a != b 2804 /* Must be simple edge. */ 2805 && !(single_succ_edge (a)->flags & EDGE_COMPLEX) 2806 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR 2807 /* If the jump insn has side effects, we can't kill the edge. 2808 When not optimizing, try_redirect_by_replacing_jump will 2809 not allow us to redirect an edge by replacing a table jump. */ 2810 && (!JUMP_P (BB_END (a)) 2811 || ((!optimize || reload_completed) 2812 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a))))); 2813 } 2814 2815 /* Merge block A and B. The blocks must be mergeable. */ 2816 2817 static void 2818 cfg_layout_merge_blocks (basic_block a, basic_block b) 2819 { 2820 bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0; 2821 2822 gcc_checking_assert (cfg_layout_can_merge_blocks_p (a, b)); 2823 2824 if (dump_file) 2825 fprintf (dump_file, "Merging block %d into block %d...\n", b->index, 2826 a->index); 2827 2828 /* If there was a CODE_LABEL beginning B, delete it. */ 2829 if (LABEL_P (BB_HEAD (b))) 2830 { 2831 delete_insn (BB_HEAD (b)); 2832 } 2833 2834 /* We should have fallthru edge in a, or we can do dummy redirection to get 2835 it cleaned up. */ 2836 if (JUMP_P (BB_END (a))) 2837 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true); 2838 gcc_assert (!JUMP_P (BB_END (a))); 2839 2840 /* When not optimizing and the edge is the only place in RTL which holds 2841 some unique locus, emit a nop with that locus in between. */ 2842 if (!optimize && EDGE_SUCC (a, 0)->goto_locus) 2843 { 2844 rtx insn = BB_END (a), end = PREV_INSN (BB_HEAD (a)); 2845 int goto_locus = EDGE_SUCC (a, 0)->goto_locus; 2846 2847 while (insn != end && (!INSN_P (insn) || INSN_LOCATOR (insn) == 0)) 2848 insn = PREV_INSN (insn); 2849 if (insn != end && locator_eq (INSN_LOCATOR (insn), goto_locus)) 2850 goto_locus = 0; 2851 else 2852 { 2853 insn = BB_HEAD (b); 2854 end = NEXT_INSN (BB_END (b)); 2855 while (insn != end && !INSN_P (insn)) 2856 insn = NEXT_INSN (insn); 2857 if (insn != end && INSN_LOCATOR (insn) != 0 2858 && locator_eq (INSN_LOCATOR (insn), goto_locus)) 2859 goto_locus = 0; 2860 } 2861 if (goto_locus) 2862 { 2863 BB_END (a) = emit_insn_after_noloc (gen_nop (), BB_END (a), a); 2864 INSN_LOCATOR (BB_END (a)) = goto_locus; 2865 } 2866 } 2867 2868 /* Possible line number notes should appear in between. */ 2869 if (b->il.rtl->header) 2870 { 2871 rtx first = BB_END (a), last; 2872 2873 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a); 2874 /* The above might add a BARRIER as BB_END, but as barriers 2875 aren't valid parts of a bb, remove_insn doesn't update 2876 BB_END if it is a barrier. So adjust BB_END here. */ 2877 while (BB_END (a) != first && BARRIER_P (BB_END (a))) 2878 BB_END (a) = PREV_INSN (BB_END (a)); 2879 delete_insn_chain (NEXT_INSN (first), last, false); 2880 b->il.rtl->header = NULL; 2881 } 2882 2883 /* In the case basic blocks are not adjacent, move them around. */ 2884 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b)) 2885 { 2886 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b)); 2887 2888 emit_insn_after_noloc (first, BB_END (a), a); 2889 /* Skip possible DELETED_LABEL insn. */ 2890 if (!NOTE_INSN_BASIC_BLOCK_P (first)) 2891 first = NEXT_INSN (first); 2892 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first)); 2893 BB_HEAD (b) = NULL; 2894 2895 /* emit_insn_after_noloc doesn't call df_insn_change_bb. 2896 We need to explicitly call. */ 2897 update_bb_for_insn_chain (NEXT_INSN (first), 2898 BB_END (b), 2899 a); 2900 2901 delete_insn (first); 2902 } 2903 /* Otherwise just re-associate the instructions. */ 2904 else 2905 { 2906 rtx insn; 2907 2908 update_bb_for_insn_chain (BB_HEAD (b), BB_END (b), a); 2909 2910 insn = BB_HEAD (b); 2911 /* Skip possible DELETED_LABEL insn. */ 2912 if (!NOTE_INSN_BASIC_BLOCK_P (insn)) 2913 insn = NEXT_INSN (insn); 2914 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn)); 2915 BB_HEAD (b) = NULL; 2916 BB_END (a) = BB_END (b); 2917 delete_insn (insn); 2918 } 2919 2920 df_bb_delete (b->index); 2921 2922 /* Possible tablejumps and barriers should appear after the block. */ 2923 if (b->il.rtl->footer) 2924 { 2925 if (!a->il.rtl->footer) 2926 a->il.rtl->footer = b->il.rtl->footer; 2927 else 2928 { 2929 rtx last = a->il.rtl->footer; 2930 2931 while (NEXT_INSN (last)) 2932 last = NEXT_INSN (last); 2933 NEXT_INSN (last) = b->il.rtl->footer; 2934 PREV_INSN (b->il.rtl->footer) = last; 2935 } 2936 b->il.rtl->footer = NULL; 2937 } 2938 2939 /* If B was a forwarder block, propagate the locus on the edge. */ 2940 if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus) 2941 EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus; 2942 2943 if (dump_file) 2944 fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index); 2945 } 2946 2947 /* Split edge E. */ 2948 2949 static basic_block 2950 cfg_layout_split_edge (edge e) 2951 { 2952 basic_block new_bb = 2953 create_basic_block (e->src != ENTRY_BLOCK_PTR 2954 ? NEXT_INSN (BB_END (e->src)) : get_insns (), 2955 NULL_RTX, e->src); 2956 2957 if (e->dest == EXIT_BLOCK_PTR) 2958 BB_COPY_PARTITION (new_bb, e->src); 2959 else 2960 BB_COPY_PARTITION (new_bb, e->dest); 2961 make_edge (new_bb, e->dest, EDGE_FALLTHRU); 2962 redirect_edge_and_branch_force (e, new_bb); 2963 2964 return new_bb; 2965 } 2966 2967 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */ 2968 2969 static void 2970 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED) 2971 { 2972 } 2973 2974 /* Return 1 if BB ends with a call, possibly followed by some 2975 instructions that must stay with the call, 0 otherwise. */ 2976 2977 static bool 2978 rtl_block_ends_with_call_p (basic_block bb) 2979 { 2980 rtx insn = BB_END (bb); 2981 2982 while (!CALL_P (insn) 2983 && insn != BB_HEAD (bb) 2984 && (keep_with_call_p (insn) 2985 || NOTE_P (insn) 2986 || DEBUG_INSN_P (insn))) 2987 insn = PREV_INSN (insn); 2988 return (CALL_P (insn)); 2989 } 2990 2991 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */ 2992 2993 static bool 2994 rtl_block_ends_with_condjump_p (const_basic_block bb) 2995 { 2996 return any_condjump_p (BB_END (bb)); 2997 } 2998 2999 /* Return true if we need to add fake edge to exit. 3000 Helper function for rtl_flow_call_edges_add. */ 3001 3002 static bool 3003 need_fake_edge_p (const_rtx insn) 3004 { 3005 if (!INSN_P (insn)) 3006 return false; 3007 3008 if ((CALL_P (insn) 3009 && !SIBLING_CALL_P (insn) 3010 && !find_reg_note (insn, REG_NORETURN, NULL) 3011 && !(RTL_CONST_OR_PURE_CALL_P (insn)))) 3012 return true; 3013 3014 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS 3015 && MEM_VOLATILE_P (PATTERN (insn))) 3016 || (GET_CODE (PATTERN (insn)) == PARALLEL 3017 && asm_noperands (insn) != -1 3018 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0))) 3019 || GET_CODE (PATTERN (insn)) == ASM_INPUT); 3020 } 3021 3022 /* Add fake edges to the function exit for any non constant and non noreturn 3023 calls, volatile inline assembly in the bitmap of blocks specified by 3024 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks 3025 that were split. 3026 3027 The goal is to expose cases in which entering a basic block does not imply 3028 that all subsequent instructions must be executed. */ 3029 3030 static int 3031 rtl_flow_call_edges_add (sbitmap blocks) 3032 { 3033 int i; 3034 int blocks_split = 0; 3035 int last_bb = last_basic_block; 3036 bool check_last_block = false; 3037 3038 if (n_basic_blocks == NUM_FIXED_BLOCKS) 3039 return 0; 3040 3041 if (! blocks) 3042 check_last_block = true; 3043 else 3044 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index); 3045 3046 /* In the last basic block, before epilogue generation, there will be 3047 a fallthru edge to EXIT. Special care is required if the last insn 3048 of the last basic block is a call because make_edge folds duplicate 3049 edges, which would result in the fallthru edge also being marked 3050 fake, which would result in the fallthru edge being removed by 3051 remove_fake_edges, which would result in an invalid CFG. 3052 3053 Moreover, we can't elide the outgoing fake edge, since the block 3054 profiler needs to take this into account in order to solve the minimal 3055 spanning tree in the case that the call doesn't return. 3056 3057 Handle this by adding a dummy instruction in a new last basic block. */ 3058 if (check_last_block) 3059 { 3060 basic_block bb = EXIT_BLOCK_PTR->prev_bb; 3061 rtx insn = BB_END (bb); 3062 3063 /* Back up past insns that must be kept in the same block as a call. */ 3064 while (insn != BB_HEAD (bb) 3065 && keep_with_call_p (insn)) 3066 insn = PREV_INSN (insn); 3067 3068 if (need_fake_edge_p (insn)) 3069 { 3070 edge e; 3071 3072 e = find_edge (bb, EXIT_BLOCK_PTR); 3073 if (e) 3074 { 3075 insert_insn_on_edge (gen_use (const0_rtx), e); 3076 commit_edge_insertions (); 3077 } 3078 } 3079 } 3080 3081 /* Now add fake edges to the function exit for any non constant 3082 calls since there is no way that we can determine if they will 3083 return or not... */ 3084 3085 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++) 3086 { 3087 basic_block bb = BASIC_BLOCK (i); 3088 rtx insn; 3089 rtx prev_insn; 3090 3091 if (!bb) 3092 continue; 3093 3094 if (blocks && !TEST_BIT (blocks, i)) 3095 continue; 3096 3097 for (insn = BB_END (bb); ; insn = prev_insn) 3098 { 3099 prev_insn = PREV_INSN (insn); 3100 if (need_fake_edge_p (insn)) 3101 { 3102 edge e; 3103 rtx split_at_insn = insn; 3104 3105 /* Don't split the block between a call and an insn that should 3106 remain in the same block as the call. */ 3107 if (CALL_P (insn)) 3108 while (split_at_insn != BB_END (bb) 3109 && keep_with_call_p (NEXT_INSN (split_at_insn))) 3110 split_at_insn = NEXT_INSN (split_at_insn); 3111 3112 /* The handling above of the final block before the epilogue 3113 should be enough to verify that there is no edge to the exit 3114 block in CFG already. Calling make_edge in such case would 3115 cause us to mark that edge as fake and remove it later. */ 3116 3117 #ifdef ENABLE_CHECKING 3118 if (split_at_insn == BB_END (bb)) 3119 { 3120 e = find_edge (bb, EXIT_BLOCK_PTR); 3121 gcc_assert (e == NULL); 3122 } 3123 #endif 3124 3125 /* Note that the following may create a new basic block 3126 and renumber the existing basic blocks. */ 3127 if (split_at_insn != BB_END (bb)) 3128 { 3129 e = split_block (bb, split_at_insn); 3130 if (e) 3131 blocks_split++; 3132 } 3133 3134 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); 3135 } 3136 3137 if (insn == BB_HEAD (bb)) 3138 break; 3139 } 3140 } 3141 3142 if (blocks_split) 3143 verify_flow_info (); 3144 3145 return blocks_split; 3146 } 3147 3148 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is 3149 the conditional branch target, SECOND_HEAD should be the fall-thru 3150 there is no need to handle this here the loop versioning code handles 3151 this. the reason for SECON_HEAD is that it is needed for condition 3152 in trees, and this should be of the same type since it is a hook. */ 3153 static void 3154 rtl_lv_add_condition_to_bb (basic_block first_head , 3155 basic_block second_head ATTRIBUTE_UNUSED, 3156 basic_block cond_bb, void *comp_rtx) 3157 { 3158 rtx label, seq, jump; 3159 rtx op0 = XEXP ((rtx)comp_rtx, 0); 3160 rtx op1 = XEXP ((rtx)comp_rtx, 1); 3161 enum rtx_code comp = GET_CODE ((rtx)comp_rtx); 3162 enum machine_mode mode; 3163 3164 3165 label = block_label (first_head); 3166 mode = GET_MODE (op0); 3167 if (mode == VOIDmode) 3168 mode = GET_MODE (op1); 3169 3170 start_sequence (); 3171 op0 = force_operand (op0, NULL_RTX); 3172 op1 = force_operand (op1, NULL_RTX); 3173 do_compare_rtx_and_jump (op0, op1, comp, 0, 3174 mode, NULL_RTX, NULL_RTX, label, -1); 3175 jump = get_last_insn (); 3176 JUMP_LABEL (jump) = label; 3177 LABEL_NUSES (label)++; 3178 seq = get_insns (); 3179 end_sequence (); 3180 3181 /* Add the new cond , in the new head. */ 3182 emit_insn_after(seq, BB_END(cond_bb)); 3183 } 3184 3185 3186 /* Given a block B with unconditional branch at its end, get the 3187 store the return the branch edge and the fall-thru edge in 3188 BRANCH_EDGE and FALLTHRU_EDGE respectively. */ 3189 static void 3190 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge, 3191 edge *fallthru_edge) 3192 { 3193 edge e = EDGE_SUCC (b, 0); 3194 3195 if (e->flags & EDGE_FALLTHRU) 3196 { 3197 *fallthru_edge = e; 3198 *branch_edge = EDGE_SUCC (b, 1); 3199 } 3200 else 3201 { 3202 *branch_edge = e; 3203 *fallthru_edge = EDGE_SUCC (b, 1); 3204 } 3205 } 3206 3207 void 3208 init_rtl_bb_info (basic_block bb) 3209 { 3210 gcc_assert (!bb->il.rtl); 3211 bb->il.rtl = ggc_alloc_cleared_rtl_bb_info (); 3212 } 3213 3214 /* Returns true if it is possible to remove edge E by redirecting 3215 it to the destination of the other edge from E->src. */ 3216 3217 static bool 3218 rtl_can_remove_branch_p (const_edge e) 3219 { 3220 const_basic_block src = e->src; 3221 const_basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest; 3222 const_rtx insn = BB_END (src), set; 3223 3224 /* The conditions are taken from try_redirect_by_replacing_jump. */ 3225 if (target == EXIT_BLOCK_PTR) 3226 return false; 3227 3228 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) 3229 return false; 3230 3231 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX) 3232 || BB_PARTITION (src) != BB_PARTITION (target)) 3233 return false; 3234 3235 if (!onlyjump_p (insn) 3236 || tablejump_p (insn, NULL, NULL)) 3237 return false; 3238 3239 set = single_set (insn); 3240 if (!set || side_effects_p (set)) 3241 return false; 3242 3243 return true; 3244 } 3245 3246 /* We do not want to declare these functions in a header file, since they 3247 should only be used through the cfghooks interface, and we do not want to 3248 move them here since it would require also moving quite a lot of related 3249 code. They are in cfglayout.c. */ 3250 extern bool cfg_layout_can_duplicate_bb_p (const_basic_block); 3251 extern basic_block cfg_layout_duplicate_bb (basic_block); 3252 3253 static basic_block 3254 rtl_duplicate_bb (basic_block bb) 3255 { 3256 bb = cfg_layout_duplicate_bb (bb); 3257 bb->aux = NULL; 3258 return bb; 3259 } 3260 3261 /* Implementation of CFG manipulation for linearized RTL. */ 3262 struct cfg_hooks rtl_cfg_hooks = { 3263 "rtl", 3264 rtl_verify_flow_info, 3265 rtl_dump_bb, 3266 rtl_create_basic_block, 3267 rtl_redirect_edge_and_branch, 3268 rtl_redirect_edge_and_branch_force, 3269 rtl_can_remove_branch_p, 3270 rtl_delete_block, 3271 rtl_split_block, 3272 rtl_move_block_after, 3273 rtl_can_merge_blocks, /* can_merge_blocks_p */ 3274 rtl_merge_blocks, 3275 rtl_predict_edge, 3276 rtl_predicted_by_p, 3277 cfg_layout_can_duplicate_bb_p, 3278 rtl_duplicate_bb, 3279 rtl_split_edge, 3280 rtl_make_forwarder_block, 3281 rtl_tidy_fallthru_edge, 3282 rtl_force_nonfallthru, 3283 rtl_block_ends_with_call_p, 3284 rtl_block_ends_with_condjump_p, 3285 rtl_flow_call_edges_add, 3286 NULL, /* execute_on_growing_pred */ 3287 NULL, /* execute_on_shrinking_pred */ 3288 NULL, /* duplicate loop for trees */ 3289 NULL, /* lv_add_condition_to_bb */ 3290 NULL, /* lv_adjust_loop_header_phi*/ 3291 NULL, /* extract_cond_bb_edges */ 3292 NULL /* flush_pending_stmts */ 3293 }; 3294 3295 /* Implementation of CFG manipulation for cfg layout RTL, where 3296 basic block connected via fallthru edges does not have to be adjacent. 3297 This representation will hopefully become the default one in future 3298 version of the compiler. */ 3299 3300 struct cfg_hooks cfg_layout_rtl_cfg_hooks = { 3301 "cfglayout mode", 3302 rtl_verify_flow_info_1, 3303 rtl_dump_bb, 3304 cfg_layout_create_basic_block, 3305 cfg_layout_redirect_edge_and_branch, 3306 cfg_layout_redirect_edge_and_branch_force, 3307 rtl_can_remove_branch_p, 3308 cfg_layout_delete_block, 3309 cfg_layout_split_block, 3310 rtl_move_block_after, 3311 cfg_layout_can_merge_blocks_p, 3312 cfg_layout_merge_blocks, 3313 rtl_predict_edge, 3314 rtl_predicted_by_p, 3315 cfg_layout_can_duplicate_bb_p, 3316 cfg_layout_duplicate_bb, 3317 cfg_layout_split_edge, 3318 rtl_make_forwarder_block, 3319 NULL, /* tidy_fallthru_edge */ 3320 rtl_force_nonfallthru, 3321 rtl_block_ends_with_call_p, 3322 rtl_block_ends_with_condjump_p, 3323 rtl_flow_call_edges_add, 3324 NULL, /* execute_on_growing_pred */ 3325 NULL, /* execute_on_shrinking_pred */ 3326 duplicate_loop_to_header_edge, /* duplicate loop for trees */ 3327 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */ 3328 NULL, /* lv_adjust_loop_header_phi*/ 3329 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */ 3330 NULL /* flush_pending_stmts */ 3331 }; 3332