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 bool adjust_jump_target = false; 1235 1236 for (i = 0; i < n; ++i) 1237 { 1238 if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (e->dest)) 1239 { 1240 LABEL_NUSES (XEXP (ASM_OPERANDS_LABEL (note, i), 0))--; 1241 XEXP (ASM_OPERANDS_LABEL (note, i), 0) = block_label (target); 1242 LABEL_NUSES (XEXP (ASM_OPERANDS_LABEL (note, i), 0))++; 1243 adjust_jump_target = true; 1244 } 1245 if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (target)) 1246 asm_goto_edge = true; 1247 } 1248 if (adjust_jump_target) 1249 { 1250 rtx insn = BB_END (e->src), note; 1251 rtx old_label = BB_HEAD (e->dest); 1252 rtx new_label = BB_HEAD (target); 1253 1254 if (JUMP_LABEL (insn) == old_label) 1255 { 1256 JUMP_LABEL (insn) = new_label; 1257 note = find_reg_note (insn, REG_LABEL_TARGET, new_label); 1258 if (note) 1259 remove_note (insn, note); 1260 } 1261 else 1262 { 1263 note = find_reg_note (insn, REG_LABEL_TARGET, old_label); 1264 if (note) 1265 remove_note (insn, note); 1266 if (JUMP_LABEL (insn) != new_label 1267 && !find_reg_note (insn, REG_LABEL_TARGET, new_label)) 1268 add_reg_note (insn, REG_LABEL_TARGET, new_label); 1269 } 1270 while ((note = find_reg_note (insn, REG_LABEL_OPERAND, old_label)) 1271 != NULL_RTX) 1272 XEXP (note, 0) = new_label; 1273 } 1274 } 1275 1276 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags || asm_goto_edge) 1277 { 1278 gcov_type count = e->count; 1279 int probability = e->probability; 1280 /* Create the new structures. */ 1281 1282 /* If the old block ended with a tablejump, skip its table 1283 by searching forward from there. Otherwise start searching 1284 forward from the last instruction of the old block. */ 1285 if (!tablejump_p (BB_END (e->src), NULL, ¬e)) 1286 note = BB_END (e->src); 1287 note = NEXT_INSN (note); 1288 1289 jump_block = create_basic_block (note, NULL, e->src); 1290 jump_block->count = count; 1291 jump_block->frequency = EDGE_FREQUENCY (e); 1292 jump_block->loop_depth = target->loop_depth; 1293 1294 /* Make sure new block ends up in correct hot/cold section. */ 1295 1296 BB_COPY_PARTITION (jump_block, e->src); 1297 if (flag_reorder_blocks_and_partition 1298 && targetm_common.have_named_sections 1299 && JUMP_P (BB_END (jump_block)) 1300 && !any_condjump_p (BB_END (jump_block)) 1301 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING)) 1302 add_reg_note (BB_END (jump_block), REG_CROSSING_JUMP, NULL_RTX); 1303 1304 /* Wire edge in. */ 1305 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU); 1306 new_edge->probability = probability; 1307 new_edge->count = count; 1308 1309 /* Redirect old edge. */ 1310 redirect_edge_pred (e, jump_block); 1311 e->probability = REG_BR_PROB_BASE; 1312 1313 /* If asm goto has any label refs to target's label, 1314 add also edge from asm goto bb to target. */ 1315 if (asm_goto_edge) 1316 { 1317 new_edge->probability /= 2; 1318 new_edge->count /= 2; 1319 jump_block->count /= 2; 1320 jump_block->frequency /= 2; 1321 new_edge = make_edge (new_edge->src, target, 1322 e->flags & ~EDGE_FALLTHRU); 1323 new_edge->probability = probability - probability / 2; 1324 new_edge->count = count - count / 2; 1325 } 1326 1327 new_bb = jump_block; 1328 } 1329 else 1330 jump_block = e->src; 1331 1332 if (e->goto_locus && e->goto_block == NULL) 1333 loc = e->goto_locus; 1334 else 1335 loc = 0; 1336 e->flags &= ~EDGE_FALLTHRU; 1337 if (target == EXIT_BLOCK_PTR) 1338 { 1339 if (jump_label == ret_rtx) 1340 { 1341 #ifdef HAVE_return 1342 emit_jump_insn_after_setloc (gen_return (), BB_END (jump_block), loc); 1343 #else 1344 gcc_unreachable (); 1345 #endif 1346 } 1347 else 1348 { 1349 gcc_assert (jump_label == simple_return_rtx); 1350 #ifdef HAVE_simple_return 1351 emit_jump_insn_after_setloc (gen_simple_return (), 1352 BB_END (jump_block), loc); 1353 #else 1354 gcc_unreachable (); 1355 #endif 1356 } 1357 set_return_jump_label (BB_END (jump_block)); 1358 } 1359 else 1360 { 1361 rtx label = block_label (target); 1362 emit_jump_insn_after_setloc (gen_jump (label), BB_END (jump_block), loc); 1363 JUMP_LABEL (BB_END (jump_block)) = label; 1364 LABEL_NUSES (label)++; 1365 } 1366 1367 emit_barrier_after (BB_END (jump_block)); 1368 redirect_edge_succ_nodup (e, target); 1369 1370 if (abnormal_edge_flags) 1371 make_edge (src, target, abnormal_edge_flags); 1372 1373 df_mark_solutions_dirty (); 1374 return new_bb; 1375 } 1376 1377 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction 1378 (and possibly create new basic block) to make edge non-fallthru. 1379 Return newly created BB or NULL if none. */ 1380 1381 static basic_block 1382 rtl_force_nonfallthru (edge e) 1383 { 1384 return force_nonfallthru_and_redirect (e, e->dest, NULL_RTX); 1385 } 1386 1387 /* Redirect edge even at the expense of creating new jump insn or 1388 basic block. Return new basic block if created, NULL otherwise. 1389 Conversion must be possible. */ 1390 1391 static basic_block 1392 rtl_redirect_edge_and_branch_force (edge e, basic_block target) 1393 { 1394 if (redirect_edge_and_branch (e, target) 1395 || e->dest == target) 1396 return NULL; 1397 1398 /* In case the edge redirection failed, try to force it to be non-fallthru 1399 and redirect newly created simplejump. */ 1400 df_set_bb_dirty (e->src); 1401 return force_nonfallthru_and_redirect (e, target, NULL_RTX); 1402 } 1403 1404 /* The given edge should potentially be a fallthru edge. If that is in 1405 fact true, delete the jump and barriers that are in the way. */ 1406 1407 static void 1408 rtl_tidy_fallthru_edge (edge e) 1409 { 1410 rtx q; 1411 basic_block b = e->src, c = b->next_bb; 1412 1413 /* ??? In a late-running flow pass, other folks may have deleted basic 1414 blocks by nopping out blocks, leaving multiple BARRIERs between here 1415 and the target label. They ought to be chastised and fixed. 1416 1417 We can also wind up with a sequence of undeletable labels between 1418 one block and the next. 1419 1420 So search through a sequence of barriers, labels, and notes for 1421 the head of block C and assert that we really do fall through. */ 1422 1423 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q)) 1424 if (INSN_P (q)) 1425 return; 1426 1427 /* Remove what will soon cease being the jump insn from the source block. 1428 If block B consisted only of this single jump, turn it into a deleted 1429 note. */ 1430 q = BB_END (b); 1431 if (JUMP_P (q) 1432 && onlyjump_p (q) 1433 && (any_uncondjump_p (q) 1434 || single_succ_p (b))) 1435 { 1436 #ifdef HAVE_cc0 1437 /* If this was a conditional jump, we need to also delete 1438 the insn that set cc0. */ 1439 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q))) 1440 q = PREV_INSN (q); 1441 #endif 1442 1443 q = PREV_INSN (q); 1444 } 1445 1446 /* Selectively unlink the sequence. */ 1447 if (q != PREV_INSN (BB_HEAD (c))) 1448 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)), false); 1449 1450 e->flags |= EDGE_FALLTHRU; 1451 } 1452 1453 /* Should move basic block BB after basic block AFTER. NIY. */ 1454 1455 static bool 1456 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED, 1457 basic_block after ATTRIBUTE_UNUSED) 1458 { 1459 return false; 1460 } 1461 1462 /* Split a (typically critical) edge. Return the new block. 1463 The edge must not be abnormal. 1464 1465 ??? The code generally expects to be called on critical edges. 1466 The case of a block ending in an unconditional jump to a 1467 block with multiple predecessors is not handled optimally. */ 1468 1469 static basic_block 1470 rtl_split_edge (edge edge_in) 1471 { 1472 basic_block bb; 1473 rtx before; 1474 1475 /* Abnormal edges cannot be split. */ 1476 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL)); 1477 1478 /* We are going to place the new block in front of edge destination. 1479 Avoid existence of fallthru predecessors. */ 1480 if ((edge_in->flags & EDGE_FALLTHRU) == 0) 1481 { 1482 edge e = find_fallthru_edge (edge_in->dest->preds); 1483 1484 if (e) 1485 force_nonfallthru (e); 1486 } 1487 1488 /* Create the basic block note. */ 1489 if (edge_in->dest != EXIT_BLOCK_PTR) 1490 before = BB_HEAD (edge_in->dest); 1491 else 1492 before = NULL_RTX; 1493 1494 /* If this is a fall through edge to the exit block, the blocks might be 1495 not adjacent, and the right place is after the source. */ 1496 if ((edge_in->flags & EDGE_FALLTHRU) && edge_in->dest == EXIT_BLOCK_PTR) 1497 { 1498 before = NEXT_INSN (BB_END (edge_in->src)); 1499 bb = create_basic_block (before, NULL, edge_in->src); 1500 BB_COPY_PARTITION (bb, edge_in->src); 1501 } 1502 else 1503 { 1504 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb); 1505 /* ??? Why not edge_in->dest->prev_bb here? */ 1506 BB_COPY_PARTITION (bb, edge_in->dest); 1507 } 1508 1509 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU); 1510 1511 /* For non-fallthru edges, we must adjust the predecessor's 1512 jump instruction to target our new block. */ 1513 if ((edge_in->flags & EDGE_FALLTHRU) == 0) 1514 { 1515 edge redirected = redirect_edge_and_branch (edge_in, bb); 1516 gcc_assert (redirected); 1517 } 1518 else 1519 { 1520 if (edge_in->src != ENTRY_BLOCK_PTR) 1521 { 1522 /* For asm goto even splitting of fallthru edge might 1523 need insn patching, as other labels might point to the 1524 old label. */ 1525 rtx last = BB_END (edge_in->src); 1526 if (last 1527 && JUMP_P (last) 1528 && edge_in->dest != EXIT_BLOCK_PTR 1529 && extract_asm_operands (PATTERN (last)) != NULL_RTX 1530 && patch_jump_insn (last, before, bb)) 1531 df_set_bb_dirty (edge_in->src); 1532 } 1533 redirect_edge_succ (edge_in, bb); 1534 } 1535 1536 return bb; 1537 } 1538 1539 /* Queue instructions for insertion on an edge between two basic blocks. 1540 The new instructions and basic blocks (if any) will not appear in the 1541 CFG until commit_edge_insertions is called. */ 1542 1543 void 1544 insert_insn_on_edge (rtx pattern, edge e) 1545 { 1546 /* We cannot insert instructions on an abnormal critical edge. 1547 It will be easier to find the culprit if we die now. */ 1548 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e))); 1549 1550 if (e->insns.r == NULL_RTX) 1551 start_sequence (); 1552 else 1553 push_to_sequence (e->insns.r); 1554 1555 emit_insn (pattern); 1556 1557 e->insns.r = get_insns (); 1558 end_sequence (); 1559 } 1560 1561 /* Update the CFG for the instructions queued on edge E. */ 1562 1563 void 1564 commit_one_edge_insertion (edge e) 1565 { 1566 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last; 1567 basic_block bb; 1568 1569 /* Pull the insns off the edge now since the edge might go away. */ 1570 insns = e->insns.r; 1571 e->insns.r = NULL_RTX; 1572 1573 /* Figure out where to put these insns. If the destination has 1574 one predecessor, insert there. Except for the exit block. */ 1575 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR) 1576 { 1577 bb = e->dest; 1578 1579 /* Get the location correct wrt a code label, and "nice" wrt 1580 a basic block note, and before everything else. */ 1581 tmp = BB_HEAD (bb); 1582 if (LABEL_P (tmp)) 1583 tmp = NEXT_INSN (tmp); 1584 if (NOTE_INSN_BASIC_BLOCK_P (tmp)) 1585 tmp = NEXT_INSN (tmp); 1586 if (tmp == BB_HEAD (bb)) 1587 before = tmp; 1588 else if (tmp) 1589 after = PREV_INSN (tmp); 1590 else 1591 after = get_last_insn (); 1592 } 1593 1594 /* If the source has one successor and the edge is not abnormal, 1595 insert there. Except for the entry block. */ 1596 else if ((e->flags & EDGE_ABNORMAL) == 0 1597 && single_succ_p (e->src) 1598 && e->src != ENTRY_BLOCK_PTR) 1599 { 1600 bb = e->src; 1601 1602 /* It is possible to have a non-simple jump here. Consider a target 1603 where some forms of unconditional jumps clobber a register. This 1604 happens on the fr30 for example. 1605 1606 We know this block has a single successor, so we can just emit 1607 the queued insns before the jump. */ 1608 if (JUMP_P (BB_END (bb))) 1609 before = BB_END (bb); 1610 else 1611 { 1612 /* We'd better be fallthru, or we've lost track of what's what. */ 1613 gcc_assert (e->flags & EDGE_FALLTHRU); 1614 1615 after = BB_END (bb); 1616 } 1617 } 1618 1619 /* Otherwise we must split the edge. */ 1620 else 1621 { 1622 bb = split_edge (e); 1623 after = BB_END (bb); 1624 1625 if (flag_reorder_blocks_and_partition 1626 && targetm_common.have_named_sections 1627 && e->src != ENTRY_BLOCK_PTR 1628 && BB_PARTITION (e->src) == BB_COLD_PARTITION 1629 && !(e->flags & EDGE_CROSSING) 1630 && JUMP_P (after) 1631 && !any_condjump_p (after) 1632 && (single_succ_edge (bb)->flags & EDGE_CROSSING)) 1633 add_reg_note (after, REG_CROSSING_JUMP, NULL_RTX); 1634 } 1635 1636 /* Now that we've found the spot, do the insertion. */ 1637 if (before) 1638 { 1639 emit_insn_before_noloc (insns, before, bb); 1640 last = prev_nonnote_insn (before); 1641 } 1642 else 1643 last = emit_insn_after_noloc (insns, after, bb); 1644 1645 if (returnjump_p (last)) 1646 { 1647 /* ??? Remove all outgoing edges from BB and add one for EXIT. 1648 This is not currently a problem because this only happens 1649 for the (single) epilogue, which already has a fallthru edge 1650 to EXIT. */ 1651 1652 e = single_succ_edge (bb); 1653 gcc_assert (e->dest == EXIT_BLOCK_PTR 1654 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU)); 1655 1656 e->flags &= ~EDGE_FALLTHRU; 1657 emit_barrier_after (last); 1658 1659 if (before) 1660 delete_insn (before); 1661 } 1662 else 1663 gcc_assert (!JUMP_P (last)); 1664 } 1665 1666 /* Update the CFG for all queued instructions. */ 1667 1668 void 1669 commit_edge_insertions (void) 1670 { 1671 basic_block bb; 1672 1673 #ifdef ENABLE_CHECKING 1674 verify_flow_info (); 1675 #endif 1676 1677 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb) 1678 { 1679 edge e; 1680 edge_iterator ei; 1681 1682 FOR_EACH_EDGE (e, ei, bb->succs) 1683 if (e->insns.r) 1684 commit_one_edge_insertion (e); 1685 } 1686 } 1687 1688 1689 /* Print out RTL-specific basic block information (live information 1690 at start and end). */ 1691 1692 static void 1693 rtl_dump_bb (basic_block bb, FILE *outf, int indent, int flags ATTRIBUTE_UNUSED) 1694 { 1695 rtx insn; 1696 rtx last; 1697 char *s_indent; 1698 1699 s_indent = (char *) alloca ((size_t) indent + 1); 1700 memset (s_indent, ' ', (size_t) indent); 1701 s_indent[indent] = '\0'; 1702 1703 if (df) 1704 { 1705 df_dump_top (bb, outf); 1706 putc ('\n', outf); 1707 } 1708 1709 if (bb->index != ENTRY_BLOCK && bb->index != EXIT_BLOCK) 1710 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last; 1711 insn = NEXT_INSN (insn)) 1712 print_rtl_single (outf, insn); 1713 1714 if (df) 1715 { 1716 df_dump_bottom (bb, outf); 1717 putc ('\n', outf); 1718 } 1719 1720 } 1721 1722 /* Like print_rtl, but also print out live information for the start of each 1723 basic block. */ 1724 1725 void 1726 print_rtl_with_bb (FILE *outf, const_rtx rtx_first) 1727 { 1728 const_rtx tmp_rtx; 1729 if (rtx_first == 0) 1730 fprintf (outf, "(nil)\n"); 1731 else 1732 { 1733 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB }; 1734 int max_uid = get_max_uid (); 1735 basic_block *start = XCNEWVEC (basic_block, max_uid); 1736 basic_block *end = XCNEWVEC (basic_block, max_uid); 1737 enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid); 1738 1739 basic_block bb; 1740 1741 if (df) 1742 df_dump_start (outf); 1743 1744 FOR_EACH_BB_REVERSE (bb) 1745 { 1746 rtx x; 1747 1748 start[INSN_UID (BB_HEAD (bb))] = bb; 1749 end[INSN_UID (BB_END (bb))] = bb; 1750 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x)) 1751 { 1752 enum bb_state state = IN_MULTIPLE_BB; 1753 1754 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB) 1755 state = IN_ONE_BB; 1756 in_bb_p[INSN_UID (x)] = state; 1757 1758 if (x == BB_END (bb)) 1759 break; 1760 } 1761 } 1762 1763 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx)) 1764 { 1765 int did_output; 1766 1767 bb = start[INSN_UID (tmp_rtx)]; 1768 if (bb != NULL) 1769 dump_bb_info (bb, true, false, dump_flags, ";; ", outf); 1770 1771 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB 1772 && !NOTE_P (tmp_rtx) 1773 && !BARRIER_P (tmp_rtx)) 1774 fprintf (outf, ";; Insn is not within a basic block\n"); 1775 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB) 1776 fprintf (outf, ";; Insn is in multiple basic blocks\n"); 1777 1778 did_output = print_rtl_single (outf, tmp_rtx); 1779 1780 bb = end[INSN_UID (tmp_rtx)]; 1781 if (bb != NULL) 1782 dump_bb_info (bb, false, true, dump_flags, ";; ", outf); 1783 if (did_output) 1784 putc ('\n', outf); 1785 } 1786 1787 free (start); 1788 free (end); 1789 free (in_bb_p); 1790 } 1791 1792 if (crtl->epilogue_delay_list != 0) 1793 { 1794 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n"); 1795 for (tmp_rtx = crtl->epilogue_delay_list; tmp_rtx != 0; 1796 tmp_rtx = XEXP (tmp_rtx, 1)) 1797 print_rtl_single (outf, XEXP (tmp_rtx, 0)); 1798 } 1799 } 1800 1801 void 1802 update_br_prob_note (basic_block bb) 1803 { 1804 rtx note; 1805 if (!JUMP_P (BB_END (bb))) 1806 return; 1807 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX); 1808 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability) 1809 return; 1810 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability); 1811 } 1812 1813 /* Get the last insn associated with block BB (that includes barriers and 1814 tablejumps after BB). */ 1815 rtx 1816 get_last_bb_insn (basic_block bb) 1817 { 1818 rtx tmp; 1819 rtx end = BB_END (bb); 1820 1821 /* Include any jump table following the basic block. */ 1822 if (tablejump_p (end, NULL, &tmp)) 1823 end = tmp; 1824 1825 /* Include any barriers that may follow the basic block. */ 1826 tmp = next_nonnote_insn_bb (end); 1827 while (tmp && BARRIER_P (tmp)) 1828 { 1829 end = tmp; 1830 tmp = next_nonnote_insn_bb (end); 1831 } 1832 1833 return end; 1834 } 1835 1836 /* Verify the CFG and RTL consistency common for both underlying RTL and 1837 cfglayout RTL. 1838 1839 Currently it does following checks: 1840 1841 - overlapping of basic blocks 1842 - insns with wrong BLOCK_FOR_INSN pointers 1843 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note) 1844 - tails of basic blocks (ensure that boundary is necessary) 1845 - scans body of the basic block for JUMP_INSN, CODE_LABEL 1846 and NOTE_INSN_BASIC_BLOCK 1847 - verify that no fall_thru edge crosses hot/cold partition boundaries 1848 - verify that there are no pending RTL branch predictions 1849 1850 In future it can be extended check a lot of other stuff as well 1851 (reachability of basic blocks, life information, etc. etc.). */ 1852 1853 static int 1854 rtl_verify_flow_info_1 (void) 1855 { 1856 rtx x; 1857 int err = 0; 1858 basic_block bb; 1859 1860 /* Check the general integrity of the basic blocks. */ 1861 FOR_EACH_BB_REVERSE (bb) 1862 { 1863 rtx insn; 1864 1865 if (!(bb->flags & BB_RTL)) 1866 { 1867 error ("BB_RTL flag not set for block %d", bb->index); 1868 err = 1; 1869 } 1870 1871 FOR_BB_INSNS (bb, insn) 1872 if (BLOCK_FOR_INSN (insn) != bb) 1873 { 1874 error ("insn %d basic block pointer is %d, should be %d", 1875 INSN_UID (insn), 1876 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0, 1877 bb->index); 1878 err = 1; 1879 } 1880 1881 for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn)) 1882 if (!BARRIER_P (insn) 1883 && BLOCK_FOR_INSN (insn) != NULL) 1884 { 1885 error ("insn %d in header of bb %d has non-NULL basic block", 1886 INSN_UID (insn), bb->index); 1887 err = 1; 1888 } 1889 for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn)) 1890 if (!BARRIER_P (insn) 1891 && BLOCK_FOR_INSN (insn) != NULL) 1892 { 1893 error ("insn %d in footer of bb %d has non-NULL basic block", 1894 INSN_UID (insn), bb->index); 1895 err = 1; 1896 } 1897 } 1898 1899 /* Now check the basic blocks (boundaries etc.) */ 1900 FOR_EACH_BB_REVERSE (bb) 1901 { 1902 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0; 1903 edge e, fallthru = NULL; 1904 rtx note; 1905 edge_iterator ei; 1906 1907 if (JUMP_P (BB_END (bb)) 1908 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX)) 1909 && EDGE_COUNT (bb->succs) >= 2 1910 && any_condjump_p (BB_END (bb))) 1911 { 1912 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability 1913 && profile_status != PROFILE_ABSENT) 1914 { 1915 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i", 1916 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability); 1917 err = 1; 1918 } 1919 } 1920 FOR_EACH_EDGE (e, ei, bb->succs) 1921 { 1922 bool is_crossing; 1923 1924 if (e->flags & EDGE_FALLTHRU) 1925 n_fallthru++, fallthru = e; 1926 1927 is_crossing = (BB_PARTITION (e->src) != BB_PARTITION (e->dest) 1928 && e->src != ENTRY_BLOCK_PTR 1929 && e->dest != EXIT_BLOCK_PTR); 1930 if (e->flags & EDGE_CROSSING) 1931 { 1932 if (!is_crossing) 1933 { 1934 error ("EDGE_CROSSING incorrectly set across same section"); 1935 err = 1; 1936 } 1937 if (e->flags & EDGE_FALLTHRU) 1938 { 1939 error ("fallthru edge crosses section boundary (bb %i)", 1940 e->src->index); 1941 err = 1; 1942 } 1943 if (e->flags & EDGE_EH) 1944 { 1945 error ("EH edge crosses section boundary (bb %i)", 1946 e->src->index); 1947 err = 1; 1948 } 1949 } 1950 else if (is_crossing) 1951 { 1952 error ("EDGE_CROSSING missing across section boundary"); 1953 err = 1; 1954 } 1955 1956 if ((e->flags & ~(EDGE_DFS_BACK 1957 | EDGE_CAN_FALLTHRU 1958 | EDGE_IRREDUCIBLE_LOOP 1959 | EDGE_LOOP_EXIT 1960 | EDGE_CROSSING 1961 | EDGE_PRESERVE)) == 0) 1962 n_branch++; 1963 1964 if (e->flags & EDGE_ABNORMAL_CALL) 1965 n_call++; 1966 1967 if (e->flags & EDGE_EH) 1968 n_eh++; 1969 else if (e->flags & EDGE_ABNORMAL) 1970 n_abnormal++; 1971 } 1972 1973 if (n_eh && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX)) 1974 { 1975 error ("missing REG_EH_REGION note in the end of bb %i", bb->index); 1976 err = 1; 1977 } 1978 if (n_eh > 1) 1979 { 1980 error ("too many eh edges %i", bb->index); 1981 err = 1; 1982 } 1983 if (n_branch 1984 && (!JUMP_P (BB_END (bb)) 1985 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb)) 1986 || any_condjump_p (BB_END (bb)))))) 1987 { 1988 error ("too many outgoing branch edges from bb %i", bb->index); 1989 err = 1; 1990 } 1991 if (n_fallthru && any_uncondjump_p (BB_END (bb))) 1992 { 1993 error ("fallthru edge after unconditional jump %i", bb->index); 1994 err = 1; 1995 } 1996 if (n_branch != 1 && any_uncondjump_p (BB_END (bb))) 1997 { 1998 error ("wrong number of branch edges after unconditional jump %i", 1999 bb->index); 2000 err = 1; 2001 } 2002 if (n_branch != 1 && any_condjump_p (BB_END (bb)) 2003 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest)) 2004 { 2005 error ("wrong amount of branch edges after conditional jump %i", 2006 bb->index); 2007 err = 1; 2008 } 2009 if (n_call && !CALL_P (BB_END (bb))) 2010 { 2011 error ("call edges for non-call insn in bb %i", bb->index); 2012 err = 1; 2013 } 2014 if (n_abnormal 2015 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal) 2016 && (!JUMP_P (BB_END (bb)) 2017 || any_condjump_p (BB_END (bb)) 2018 || any_uncondjump_p (BB_END (bb)))) 2019 { 2020 error ("abnormal edges for no purpose in bb %i", bb->index); 2021 err = 1; 2022 } 2023 2024 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x)) 2025 /* We may have a barrier inside a basic block before dead code 2026 elimination. There is no BLOCK_FOR_INSN field in a barrier. */ 2027 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb) 2028 { 2029 debug_rtx (x); 2030 if (! BLOCK_FOR_INSN (x)) 2031 error 2032 ("insn %d inside basic block %d but block_for_insn is NULL", 2033 INSN_UID (x), bb->index); 2034 else 2035 error 2036 ("insn %d inside basic block %d but block_for_insn is %i", 2037 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index); 2038 2039 err = 1; 2040 } 2041 2042 /* OK pointers are correct. Now check the header of basic 2043 block. It ought to contain optional CODE_LABEL followed 2044 by NOTE_BASIC_BLOCK. */ 2045 x = BB_HEAD (bb); 2046 if (LABEL_P (x)) 2047 { 2048 if (BB_END (bb) == x) 2049 { 2050 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d", 2051 bb->index); 2052 err = 1; 2053 } 2054 2055 x = NEXT_INSN (x); 2056 } 2057 2058 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb) 2059 { 2060 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d", 2061 bb->index); 2062 err = 1; 2063 } 2064 2065 if (BB_END (bb) == x) 2066 /* Do checks for empty blocks here. */ 2067 ; 2068 else 2069 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x)) 2070 { 2071 if (NOTE_INSN_BASIC_BLOCK_P (x)) 2072 { 2073 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d", 2074 INSN_UID (x), bb->index); 2075 err = 1; 2076 } 2077 2078 if (x == BB_END (bb)) 2079 break; 2080 2081 if (control_flow_insn_p (x)) 2082 { 2083 error ("in basic block %d:", bb->index); 2084 fatal_insn ("flow control insn inside a basic block", x); 2085 } 2086 } 2087 } 2088 2089 /* Clean up. */ 2090 return err; 2091 } 2092 2093 /* Verify the CFG and RTL consistency common for both underlying RTL and 2094 cfglayout RTL. 2095 2096 Currently it does following checks: 2097 - all checks of rtl_verify_flow_info_1 2098 - test head/end pointers 2099 - check that all insns are in the basic blocks 2100 (except the switch handling code, barriers and notes) 2101 - check that all returns are followed by barriers 2102 - check that all fallthru edge points to the adjacent blocks. */ 2103 2104 static int 2105 rtl_verify_flow_info (void) 2106 { 2107 basic_block bb; 2108 int err = rtl_verify_flow_info_1 (); 2109 rtx x; 2110 rtx last_head = get_last_insn (); 2111 basic_block *bb_info; 2112 int num_bb_notes; 2113 const rtx rtx_first = get_insns (); 2114 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL; 2115 const int max_uid = get_max_uid (); 2116 2117 bb_info = XCNEWVEC (basic_block, max_uid); 2118 2119 FOR_EACH_BB_REVERSE (bb) 2120 { 2121 edge e; 2122 rtx head = BB_HEAD (bb); 2123 rtx end = BB_END (bb); 2124 2125 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x)) 2126 { 2127 /* Verify the end of the basic block is in the INSN chain. */ 2128 if (x == end) 2129 break; 2130 2131 /* And that the code outside of basic blocks has NULL bb field. */ 2132 if (!BARRIER_P (x) 2133 && BLOCK_FOR_INSN (x) != NULL) 2134 { 2135 error ("insn %d outside of basic blocks has non-NULL bb field", 2136 INSN_UID (x)); 2137 err = 1; 2138 } 2139 } 2140 2141 if (!x) 2142 { 2143 error ("end insn %d for block %d not found in the insn stream", 2144 INSN_UID (end), bb->index); 2145 err = 1; 2146 } 2147 2148 /* Work backwards from the end to the head of the basic block 2149 to verify the head is in the RTL chain. */ 2150 for (; x != NULL_RTX; x = PREV_INSN (x)) 2151 { 2152 /* While walking over the insn chain, verify insns appear 2153 in only one basic block. */ 2154 if (bb_info[INSN_UID (x)] != NULL) 2155 { 2156 error ("insn %d is in multiple basic blocks (%d and %d)", 2157 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index); 2158 err = 1; 2159 } 2160 2161 bb_info[INSN_UID (x)] = bb; 2162 2163 if (x == head) 2164 break; 2165 } 2166 if (!x) 2167 { 2168 error ("head insn %d for block %d not found in the insn stream", 2169 INSN_UID (head), bb->index); 2170 err = 1; 2171 } 2172 2173 last_head = PREV_INSN (x); 2174 2175 e = find_fallthru_edge (bb->succs); 2176 if (!e) 2177 { 2178 rtx insn; 2179 2180 /* Ensure existence of barrier in BB with no fallthru edges. */ 2181 for (insn = NEXT_INSN (BB_END (bb)); ; insn = NEXT_INSN (insn)) 2182 { 2183 if (!insn || NOTE_INSN_BASIC_BLOCK_P (insn)) 2184 { 2185 error ("missing barrier after block %i", bb->index); 2186 err = 1; 2187 break; 2188 } 2189 if (BARRIER_P (insn)) 2190 break; 2191 } 2192 } 2193 else if (e->src != ENTRY_BLOCK_PTR 2194 && e->dest != EXIT_BLOCK_PTR) 2195 { 2196 rtx insn; 2197 2198 if (e->src->next_bb != e->dest) 2199 { 2200 error 2201 ("verify_flow_info: Incorrect blocks for fallthru %i->%i", 2202 e->src->index, e->dest->index); 2203 err = 1; 2204 } 2205 else 2206 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest); 2207 insn = NEXT_INSN (insn)) 2208 if (BARRIER_P (insn) || INSN_P (insn)) 2209 { 2210 error ("verify_flow_info: Incorrect fallthru %i->%i", 2211 e->src->index, e->dest->index); 2212 fatal_insn ("wrong insn in the fallthru edge", insn); 2213 err = 1; 2214 } 2215 } 2216 } 2217 2218 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x)) 2219 { 2220 /* Check that the code before the first basic block has NULL 2221 bb field. */ 2222 if (!BARRIER_P (x) 2223 && BLOCK_FOR_INSN (x) != NULL) 2224 { 2225 error ("insn %d outside of basic blocks has non-NULL bb field", 2226 INSN_UID (x)); 2227 err = 1; 2228 } 2229 } 2230 free (bb_info); 2231 2232 num_bb_notes = 0; 2233 last_bb_seen = ENTRY_BLOCK_PTR; 2234 2235 for (x = rtx_first; x; x = NEXT_INSN (x)) 2236 { 2237 if (NOTE_INSN_BASIC_BLOCK_P (x)) 2238 { 2239 bb = NOTE_BASIC_BLOCK (x); 2240 2241 num_bb_notes++; 2242 if (bb != last_bb_seen->next_bb) 2243 internal_error ("basic blocks not laid down consecutively"); 2244 2245 curr_bb = last_bb_seen = bb; 2246 } 2247 2248 if (!curr_bb) 2249 { 2250 switch (GET_CODE (x)) 2251 { 2252 case BARRIER: 2253 case NOTE: 2254 break; 2255 2256 case CODE_LABEL: 2257 /* An addr_vec is placed outside any basic block. */ 2258 if (NEXT_INSN (x) 2259 && JUMP_TABLE_DATA_P (NEXT_INSN (x))) 2260 x = NEXT_INSN (x); 2261 2262 /* But in any case, non-deletable labels can appear anywhere. */ 2263 break; 2264 2265 default: 2266 fatal_insn ("insn outside basic block", x); 2267 } 2268 } 2269 2270 if (JUMP_P (x) 2271 && returnjump_p (x) && ! condjump_p (x) 2272 && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x)))) 2273 fatal_insn ("return not followed by barrier", x); 2274 if (curr_bb && x == BB_END (curr_bb)) 2275 curr_bb = NULL; 2276 } 2277 2278 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS) 2279 internal_error 2280 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)", 2281 num_bb_notes, n_basic_blocks); 2282 2283 return err; 2284 } 2285 2286 /* Assume that the preceding pass has possibly eliminated jump instructions 2287 or converted the unconditional jumps. Eliminate the edges from CFG. 2288 Return true if any edges are eliminated. */ 2289 2290 bool 2291 purge_dead_edges (basic_block bb) 2292 { 2293 edge e; 2294 rtx insn = BB_END (bb), note; 2295 bool purged = false; 2296 bool found; 2297 edge_iterator ei; 2298 2299 if (DEBUG_INSN_P (insn) && insn != BB_HEAD (bb)) 2300 do 2301 insn = PREV_INSN (insn); 2302 while ((DEBUG_INSN_P (insn) || NOTE_P (insn)) && insn != BB_HEAD (bb)); 2303 2304 /* If this instruction cannot trap, remove REG_EH_REGION notes. */ 2305 if (NONJUMP_INSN_P (insn) 2306 && (note = find_reg_note (insn, REG_EH_REGION, NULL))) 2307 { 2308 rtx eqnote; 2309 2310 if (! may_trap_p (PATTERN (insn)) 2311 || ((eqnote = find_reg_equal_equiv_note (insn)) 2312 && ! may_trap_p (XEXP (eqnote, 0)))) 2313 remove_note (insn, note); 2314 } 2315 2316 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */ 2317 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 2318 { 2319 bool remove = false; 2320 2321 /* There are three types of edges we need to handle correctly here: EH 2322 edges, abnormal call EH edges, and abnormal call non-EH edges. The 2323 latter can appear when nonlocal gotos are used. */ 2324 if (e->flags & EDGE_ABNORMAL_CALL) 2325 { 2326 if (!CALL_P (insn)) 2327 remove = true; 2328 else if (can_nonlocal_goto (insn)) 2329 ; 2330 else if ((e->flags & EDGE_EH) && can_throw_internal (insn)) 2331 ; 2332 else if (flag_tm && find_reg_note (insn, REG_TM, NULL)) 2333 ; 2334 else 2335 remove = true; 2336 } 2337 else if (e->flags & EDGE_EH) 2338 remove = !can_throw_internal (insn); 2339 2340 if (remove) 2341 { 2342 remove_edge (e); 2343 df_set_bb_dirty (bb); 2344 purged = true; 2345 } 2346 else 2347 ei_next (&ei); 2348 } 2349 2350 if (JUMP_P (insn)) 2351 { 2352 rtx note; 2353 edge b,f; 2354 edge_iterator ei; 2355 2356 /* We do care only about conditional jumps and simplejumps. */ 2357 if (!any_condjump_p (insn) 2358 && !returnjump_p (insn) 2359 && !simplejump_p (insn)) 2360 return purged; 2361 2362 /* Branch probability/prediction notes are defined only for 2363 condjumps. We've possibly turned condjump into simplejump. */ 2364 if (simplejump_p (insn)) 2365 { 2366 note = find_reg_note (insn, REG_BR_PROB, NULL); 2367 if (note) 2368 remove_note (insn, note); 2369 while ((note = find_reg_note (insn, REG_BR_PRED, NULL))) 2370 remove_note (insn, note); 2371 } 2372 2373 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 2374 { 2375 /* Avoid abnormal flags to leak from computed jumps turned 2376 into simplejumps. */ 2377 2378 e->flags &= ~EDGE_ABNORMAL; 2379 2380 /* See if this edge is one we should keep. */ 2381 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn)) 2382 /* A conditional jump can fall through into the next 2383 block, so we should keep the edge. */ 2384 { 2385 ei_next (&ei); 2386 continue; 2387 } 2388 else if (e->dest != EXIT_BLOCK_PTR 2389 && BB_HEAD (e->dest) == JUMP_LABEL (insn)) 2390 /* If the destination block is the target of the jump, 2391 keep the edge. */ 2392 { 2393 ei_next (&ei); 2394 continue; 2395 } 2396 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn)) 2397 /* If the destination block is the exit block, and this 2398 instruction is a return, then keep the edge. */ 2399 { 2400 ei_next (&ei); 2401 continue; 2402 } 2403 else if ((e->flags & EDGE_EH) && can_throw_internal (insn)) 2404 /* Keep the edges that correspond to exceptions thrown by 2405 this instruction and rematerialize the EDGE_ABNORMAL 2406 flag we just cleared above. */ 2407 { 2408 e->flags |= EDGE_ABNORMAL; 2409 ei_next (&ei); 2410 continue; 2411 } 2412 2413 /* We do not need this edge. */ 2414 df_set_bb_dirty (bb); 2415 purged = true; 2416 remove_edge (e); 2417 } 2418 2419 if (EDGE_COUNT (bb->succs) == 0 || !purged) 2420 return purged; 2421 2422 if (dump_file) 2423 fprintf (dump_file, "Purged edges from bb %i\n", bb->index); 2424 2425 if (!optimize) 2426 return purged; 2427 2428 /* Redistribute probabilities. */ 2429 if (single_succ_p (bb)) 2430 { 2431 single_succ_edge (bb)->probability = REG_BR_PROB_BASE; 2432 single_succ_edge (bb)->count = bb->count; 2433 } 2434 else 2435 { 2436 note = find_reg_note (insn, REG_BR_PROB, NULL); 2437 if (!note) 2438 return purged; 2439 2440 b = BRANCH_EDGE (bb); 2441 f = FALLTHRU_EDGE (bb); 2442 b->probability = INTVAL (XEXP (note, 0)); 2443 f->probability = REG_BR_PROB_BASE - b->probability; 2444 b->count = bb->count * b->probability / REG_BR_PROB_BASE; 2445 f->count = bb->count * f->probability / REG_BR_PROB_BASE; 2446 } 2447 2448 return purged; 2449 } 2450 else if (CALL_P (insn) && SIBLING_CALL_P (insn)) 2451 { 2452 /* First, there should not be any EH or ABCALL edges resulting 2453 from non-local gotos and the like. If there were, we shouldn't 2454 have created the sibcall in the first place. Second, there 2455 should of course never have been a fallthru edge. */ 2456 gcc_assert (single_succ_p (bb)); 2457 gcc_assert (single_succ_edge (bb)->flags 2458 == (EDGE_SIBCALL | EDGE_ABNORMAL)); 2459 2460 return 0; 2461 } 2462 2463 /* If we don't see a jump insn, we don't know exactly why the block would 2464 have been broken at this point. Look for a simple, non-fallthru edge, 2465 as these are only created by conditional branches. If we find such an 2466 edge we know that there used to be a jump here and can then safely 2467 remove all non-fallthru edges. */ 2468 found = false; 2469 FOR_EACH_EDGE (e, ei, bb->succs) 2470 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU))) 2471 { 2472 found = true; 2473 break; 2474 } 2475 2476 if (!found) 2477 return purged; 2478 2479 /* Remove all but the fake and fallthru edges. The fake edge may be 2480 the only successor for this block in the case of noreturn 2481 calls. */ 2482 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 2483 { 2484 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE))) 2485 { 2486 df_set_bb_dirty (bb); 2487 remove_edge (e); 2488 purged = true; 2489 } 2490 else 2491 ei_next (&ei); 2492 } 2493 2494 gcc_assert (single_succ_p (bb)); 2495 2496 single_succ_edge (bb)->probability = REG_BR_PROB_BASE; 2497 single_succ_edge (bb)->count = bb->count; 2498 2499 if (dump_file) 2500 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n", 2501 bb->index); 2502 return purged; 2503 } 2504 2505 /* Search all basic blocks for potentially dead edges and purge them. Return 2506 true if some edge has been eliminated. */ 2507 2508 bool 2509 purge_all_dead_edges (void) 2510 { 2511 int purged = false; 2512 basic_block bb; 2513 2514 FOR_EACH_BB (bb) 2515 { 2516 bool purged_here = purge_dead_edges (bb); 2517 2518 purged |= purged_here; 2519 } 2520 2521 return purged; 2522 } 2523 2524 /* This is used by a few passes that emit some instructions after abnormal 2525 calls, moving the basic block's end, while they in fact do want to emit 2526 them on the fallthru edge. Look for abnormal call edges, find backward 2527 the call in the block and insert the instructions on the edge instead. 2528 2529 Similarly, handle instructions throwing exceptions internally. 2530 2531 Return true when instructions have been found and inserted on edges. */ 2532 2533 bool 2534 fixup_abnormal_edges (void) 2535 { 2536 bool inserted = false; 2537 basic_block bb; 2538 2539 FOR_EACH_BB (bb) 2540 { 2541 edge e; 2542 edge_iterator ei; 2543 2544 /* Look for cases we are interested in - calls or instructions causing 2545 exceptions. */ 2546 FOR_EACH_EDGE (e, ei, bb->succs) 2547 if ((e->flags & EDGE_ABNORMAL_CALL) 2548 || ((e->flags & (EDGE_ABNORMAL | EDGE_EH)) 2549 == (EDGE_ABNORMAL | EDGE_EH))) 2550 break; 2551 2552 if (e && !CALL_P (BB_END (bb)) && !can_throw_internal (BB_END (bb))) 2553 { 2554 rtx insn; 2555 2556 /* Get past the new insns generated. Allow notes, as the insns 2557 may be already deleted. */ 2558 insn = BB_END (bb); 2559 while ((NONJUMP_INSN_P (insn) || NOTE_P (insn)) 2560 && !can_throw_internal (insn) 2561 && insn != BB_HEAD (bb)) 2562 insn = PREV_INSN (insn); 2563 2564 if (CALL_P (insn) || can_throw_internal (insn)) 2565 { 2566 rtx stop, next; 2567 2568 e = find_fallthru_edge (bb->succs); 2569 2570 stop = NEXT_INSN (BB_END (bb)); 2571 BB_END (bb) = insn; 2572 2573 for (insn = NEXT_INSN (insn); insn != stop; insn = next) 2574 { 2575 next = NEXT_INSN (insn); 2576 if (INSN_P (insn)) 2577 { 2578 delete_insn (insn); 2579 2580 /* Sometimes there's still the return value USE. 2581 If it's placed after a trapping call (i.e. that 2582 call is the last insn anyway), we have no fallthru 2583 edge. Simply delete this use and don't try to insert 2584 on the non-existent edge. */ 2585 if (GET_CODE (PATTERN (insn)) != USE) 2586 { 2587 /* We're not deleting it, we're moving it. */ 2588 INSN_DELETED_P (insn) = 0; 2589 PREV_INSN (insn) = NULL_RTX; 2590 NEXT_INSN (insn) = NULL_RTX; 2591 2592 insert_insn_on_edge (insn, e); 2593 inserted = true; 2594 } 2595 } 2596 else if (!BARRIER_P (insn)) 2597 set_block_for_insn (insn, NULL); 2598 } 2599 } 2600 2601 /* It may be that we don't find any trapping insn. In this 2602 case we discovered quite late that the insn that had been 2603 marked as can_throw_internal in fact couldn't trap at all. 2604 So we should in fact delete the EH edges out of the block. */ 2605 else 2606 purge_dead_edges (bb); 2607 } 2608 } 2609 2610 return inserted; 2611 } 2612 2613 /* Same as split_block but update cfg_layout structures. */ 2614 2615 static basic_block 2616 cfg_layout_split_block (basic_block bb, void *insnp) 2617 { 2618 rtx insn = (rtx) insnp; 2619 basic_block new_bb = rtl_split_block (bb, insn); 2620 2621 new_bb->il.rtl->footer = bb->il.rtl->footer; 2622 bb->il.rtl->footer = NULL; 2623 2624 return new_bb; 2625 } 2626 2627 /* Redirect Edge to DEST. */ 2628 static edge 2629 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest) 2630 { 2631 basic_block src = e->src; 2632 edge ret; 2633 2634 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) 2635 return NULL; 2636 2637 if (e->dest == dest) 2638 return e; 2639 2640 if (e->src != ENTRY_BLOCK_PTR 2641 && (ret = try_redirect_by_replacing_jump (e, dest, true))) 2642 { 2643 df_set_bb_dirty (src); 2644 return ret; 2645 } 2646 2647 if (e->src == ENTRY_BLOCK_PTR 2648 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX)) 2649 { 2650 if (dump_file) 2651 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n", 2652 e->src->index, dest->index); 2653 2654 df_set_bb_dirty (e->src); 2655 redirect_edge_succ (e, dest); 2656 return e; 2657 } 2658 2659 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge 2660 in the case the basic block appears to be in sequence. Avoid this 2661 transformation. */ 2662 2663 if (e->flags & EDGE_FALLTHRU) 2664 { 2665 /* Redirect any branch edges unified with the fallthru one. */ 2666 if (JUMP_P (BB_END (src)) 2667 && label_is_jump_target_p (BB_HEAD (e->dest), 2668 BB_END (src))) 2669 { 2670 edge redirected; 2671 2672 if (dump_file) 2673 fprintf (dump_file, "Fallthru edge unified with branch " 2674 "%i->%i redirected to %i\n", 2675 e->src->index, e->dest->index, dest->index); 2676 e->flags &= ~EDGE_FALLTHRU; 2677 redirected = redirect_branch_edge (e, dest); 2678 gcc_assert (redirected); 2679 redirected->flags |= EDGE_FALLTHRU; 2680 df_set_bb_dirty (redirected->src); 2681 return redirected; 2682 } 2683 /* In case we are redirecting fallthru edge to the branch edge 2684 of conditional jump, remove it. */ 2685 if (EDGE_COUNT (src->succs) == 2) 2686 { 2687 /* Find the edge that is different from E. */ 2688 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e); 2689 2690 if (s->dest == dest 2691 && any_condjump_p (BB_END (src)) 2692 && onlyjump_p (BB_END (src))) 2693 delete_insn (BB_END (src)); 2694 } 2695 if (dump_file) 2696 fprintf (dump_file, "Redirecting fallthru edge %i->%i to %i\n", 2697 e->src->index, e->dest->index, dest->index); 2698 ret = redirect_edge_succ_nodup (e, dest); 2699 } 2700 else 2701 ret = redirect_branch_edge (e, dest); 2702 2703 /* We don't want simplejumps in the insn stream during cfglayout. */ 2704 gcc_assert (!simplejump_p (BB_END (src))); 2705 2706 df_set_bb_dirty (src); 2707 return ret; 2708 } 2709 2710 /* Simple wrapper as we always can redirect fallthru edges. */ 2711 static basic_block 2712 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest) 2713 { 2714 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest); 2715 2716 gcc_assert (redirected); 2717 return NULL; 2718 } 2719 2720 /* Same as delete_basic_block but update cfg_layout structures. */ 2721 2722 static void 2723 cfg_layout_delete_block (basic_block bb) 2724 { 2725 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints; 2726 2727 if (bb->il.rtl->header) 2728 { 2729 next = BB_HEAD (bb); 2730 if (prev) 2731 NEXT_INSN (prev) = bb->il.rtl->header; 2732 else 2733 set_first_insn (bb->il.rtl->header); 2734 PREV_INSN (bb->il.rtl->header) = prev; 2735 insn = bb->il.rtl->header; 2736 while (NEXT_INSN (insn)) 2737 insn = NEXT_INSN (insn); 2738 NEXT_INSN (insn) = next; 2739 PREV_INSN (next) = insn; 2740 } 2741 next = NEXT_INSN (BB_END (bb)); 2742 if (bb->il.rtl->footer) 2743 { 2744 insn = bb->il.rtl->footer; 2745 while (insn) 2746 { 2747 if (BARRIER_P (insn)) 2748 { 2749 if (PREV_INSN (insn)) 2750 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn); 2751 else 2752 bb->il.rtl->footer = NEXT_INSN (insn); 2753 if (NEXT_INSN (insn)) 2754 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn); 2755 } 2756 if (LABEL_P (insn)) 2757 break; 2758 insn = NEXT_INSN (insn); 2759 } 2760 if (bb->il.rtl->footer) 2761 { 2762 insn = BB_END (bb); 2763 NEXT_INSN (insn) = bb->il.rtl->footer; 2764 PREV_INSN (bb->il.rtl->footer) = insn; 2765 while (NEXT_INSN (insn)) 2766 insn = NEXT_INSN (insn); 2767 NEXT_INSN (insn) = next; 2768 if (next) 2769 PREV_INSN (next) = insn; 2770 else 2771 set_last_insn (insn); 2772 } 2773 } 2774 if (bb->next_bb != EXIT_BLOCK_PTR) 2775 to = &bb->next_bb->il.rtl->header; 2776 else 2777 to = &cfg_layout_function_footer; 2778 2779 rtl_delete_block (bb); 2780 2781 if (prev) 2782 prev = NEXT_INSN (prev); 2783 else 2784 prev = get_insns (); 2785 if (next) 2786 next = PREV_INSN (next); 2787 else 2788 next = get_last_insn (); 2789 2790 if (next && NEXT_INSN (next) != prev) 2791 { 2792 remaints = unlink_insn_chain (prev, next); 2793 insn = remaints; 2794 while (NEXT_INSN (insn)) 2795 insn = NEXT_INSN (insn); 2796 NEXT_INSN (insn) = *to; 2797 if (*to) 2798 PREV_INSN (*to) = insn; 2799 *to = remaints; 2800 } 2801 } 2802 2803 /* Return true when blocks A and B can be safely merged. */ 2804 2805 static bool 2806 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b) 2807 { 2808 /* If we are partitioning hot/cold basic blocks, we don't want to 2809 mess up unconditional or indirect jumps that cross between hot 2810 and cold sections. 2811 2812 Basic block partitioning may result in some jumps that appear to 2813 be optimizable (or blocks that appear to be mergeable), but which really 2814 must be left untouched (they are required to make it safely across 2815 partition boundaries). See the comments at the top of 2816 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */ 2817 2818 if (BB_PARTITION (a) != BB_PARTITION (b)) 2819 return false; 2820 2821 /* If we would end up moving B's instructions, make sure it doesn't fall 2822 through into the exit block, since we cannot recover from a fallthrough 2823 edge into the exit block occurring in the middle of a function. */ 2824 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b)) 2825 { 2826 edge e = find_fallthru_edge (b->succs); 2827 if (e && e->dest == EXIT_BLOCK_PTR) 2828 return false; 2829 } 2830 2831 /* There must be exactly one edge in between the blocks. */ 2832 return (single_succ_p (a) 2833 && single_succ (a) == b 2834 && single_pred_p (b) == 1 2835 && a != b 2836 /* Must be simple edge. */ 2837 && !(single_succ_edge (a)->flags & EDGE_COMPLEX) 2838 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR 2839 /* If the jump insn has side effects, we can't kill the edge. 2840 When not optimizing, try_redirect_by_replacing_jump will 2841 not allow us to redirect an edge by replacing a table jump. */ 2842 && (!JUMP_P (BB_END (a)) 2843 || ((!optimize || reload_completed) 2844 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a))))); 2845 } 2846 2847 /* Merge block A and B. The blocks must be mergeable. */ 2848 2849 static void 2850 cfg_layout_merge_blocks (basic_block a, basic_block b) 2851 { 2852 bool forwarder_p = (b->flags & BB_FORWARDER_BLOCK) != 0; 2853 2854 gcc_checking_assert (cfg_layout_can_merge_blocks_p (a, b)); 2855 2856 if (dump_file) 2857 fprintf (dump_file, "Merging block %d into block %d...\n", b->index, 2858 a->index); 2859 2860 /* If there was a CODE_LABEL beginning B, delete it. */ 2861 if (LABEL_P (BB_HEAD (b))) 2862 { 2863 delete_insn (BB_HEAD (b)); 2864 } 2865 2866 /* We should have fallthru edge in a, or we can do dummy redirection to get 2867 it cleaned up. */ 2868 if (JUMP_P (BB_END (a))) 2869 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true); 2870 gcc_assert (!JUMP_P (BB_END (a))); 2871 2872 /* When not optimizing and the edge is the only place in RTL which holds 2873 some unique locus, emit a nop with that locus in between. */ 2874 if (!optimize && EDGE_SUCC (a, 0)->goto_locus) 2875 { 2876 rtx insn = BB_END (a), end = PREV_INSN (BB_HEAD (a)); 2877 int goto_locus = EDGE_SUCC (a, 0)->goto_locus; 2878 2879 while (insn != end && (!INSN_P (insn) || INSN_LOCATOR (insn) == 0)) 2880 insn = PREV_INSN (insn); 2881 if (insn != end && locator_eq (INSN_LOCATOR (insn), goto_locus)) 2882 goto_locus = 0; 2883 else 2884 { 2885 insn = BB_HEAD (b); 2886 end = NEXT_INSN (BB_END (b)); 2887 while (insn != end && !INSN_P (insn)) 2888 insn = NEXT_INSN (insn); 2889 if (insn != end && INSN_LOCATOR (insn) != 0 2890 && locator_eq (INSN_LOCATOR (insn), goto_locus)) 2891 goto_locus = 0; 2892 } 2893 if (goto_locus) 2894 { 2895 BB_END (a) = emit_insn_after_noloc (gen_nop (), BB_END (a), a); 2896 INSN_LOCATOR (BB_END (a)) = goto_locus; 2897 } 2898 } 2899 2900 /* Possible line number notes should appear in between. */ 2901 if (b->il.rtl->header) 2902 { 2903 rtx first = BB_END (a), last; 2904 2905 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a); 2906 /* The above might add a BARRIER as BB_END, but as barriers 2907 aren't valid parts of a bb, remove_insn doesn't update 2908 BB_END if it is a barrier. So adjust BB_END here. */ 2909 while (BB_END (a) != first && BARRIER_P (BB_END (a))) 2910 BB_END (a) = PREV_INSN (BB_END (a)); 2911 delete_insn_chain (NEXT_INSN (first), last, false); 2912 b->il.rtl->header = NULL; 2913 } 2914 2915 /* In the case basic blocks are not adjacent, move them around. */ 2916 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b)) 2917 { 2918 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b)); 2919 2920 emit_insn_after_noloc (first, BB_END (a), a); 2921 /* Skip possible DELETED_LABEL insn. */ 2922 if (!NOTE_INSN_BASIC_BLOCK_P (first)) 2923 first = NEXT_INSN (first); 2924 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first)); 2925 BB_HEAD (b) = NULL; 2926 2927 /* emit_insn_after_noloc doesn't call df_insn_change_bb. 2928 We need to explicitly call. */ 2929 update_bb_for_insn_chain (NEXT_INSN (first), 2930 BB_END (b), 2931 a); 2932 2933 delete_insn (first); 2934 } 2935 /* Otherwise just re-associate the instructions. */ 2936 else 2937 { 2938 rtx insn; 2939 2940 update_bb_for_insn_chain (BB_HEAD (b), BB_END (b), a); 2941 2942 insn = BB_HEAD (b); 2943 /* Skip possible DELETED_LABEL insn. */ 2944 if (!NOTE_INSN_BASIC_BLOCK_P (insn)) 2945 insn = NEXT_INSN (insn); 2946 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn)); 2947 BB_HEAD (b) = NULL; 2948 BB_END (a) = BB_END (b); 2949 delete_insn (insn); 2950 } 2951 2952 df_bb_delete (b->index); 2953 2954 /* Possible tablejumps and barriers should appear after the block. */ 2955 if (b->il.rtl->footer) 2956 { 2957 if (!a->il.rtl->footer) 2958 a->il.rtl->footer = b->il.rtl->footer; 2959 else 2960 { 2961 rtx last = a->il.rtl->footer; 2962 2963 while (NEXT_INSN (last)) 2964 last = NEXT_INSN (last); 2965 NEXT_INSN (last) = b->il.rtl->footer; 2966 PREV_INSN (b->il.rtl->footer) = last; 2967 } 2968 b->il.rtl->footer = NULL; 2969 } 2970 2971 /* If B was a forwarder block, propagate the locus on the edge. */ 2972 if (forwarder_p && !EDGE_SUCC (b, 0)->goto_locus) 2973 EDGE_SUCC (b, 0)->goto_locus = EDGE_SUCC (a, 0)->goto_locus; 2974 2975 if (dump_file) 2976 fprintf (dump_file, "Merged blocks %d and %d.\n", a->index, b->index); 2977 } 2978 2979 /* Split edge E. */ 2980 2981 static basic_block 2982 cfg_layout_split_edge (edge e) 2983 { 2984 basic_block new_bb = 2985 create_basic_block (e->src != ENTRY_BLOCK_PTR 2986 ? NEXT_INSN (BB_END (e->src)) : get_insns (), 2987 NULL_RTX, e->src); 2988 2989 if (e->dest == EXIT_BLOCK_PTR) 2990 BB_COPY_PARTITION (new_bb, e->src); 2991 else 2992 BB_COPY_PARTITION (new_bb, e->dest); 2993 make_edge (new_bb, e->dest, EDGE_FALLTHRU); 2994 redirect_edge_and_branch_force (e, new_bb); 2995 2996 return new_bb; 2997 } 2998 2999 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */ 3000 3001 static void 3002 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED) 3003 { 3004 } 3005 3006 /* Return 1 if BB ends with a call, possibly followed by some 3007 instructions that must stay with the call, 0 otherwise. */ 3008 3009 static bool 3010 rtl_block_ends_with_call_p (basic_block bb) 3011 { 3012 rtx insn = BB_END (bb); 3013 3014 while (!CALL_P (insn) 3015 && insn != BB_HEAD (bb) 3016 && (keep_with_call_p (insn) 3017 || NOTE_P (insn) 3018 || DEBUG_INSN_P (insn))) 3019 insn = PREV_INSN (insn); 3020 return (CALL_P (insn)); 3021 } 3022 3023 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */ 3024 3025 static bool 3026 rtl_block_ends_with_condjump_p (const_basic_block bb) 3027 { 3028 return any_condjump_p (BB_END (bb)); 3029 } 3030 3031 /* Return true if we need to add fake edge to exit. 3032 Helper function for rtl_flow_call_edges_add. */ 3033 3034 static bool 3035 need_fake_edge_p (const_rtx insn) 3036 { 3037 if (!INSN_P (insn)) 3038 return false; 3039 3040 if ((CALL_P (insn) 3041 && !SIBLING_CALL_P (insn) 3042 && !find_reg_note (insn, REG_NORETURN, NULL) 3043 && !(RTL_CONST_OR_PURE_CALL_P (insn)))) 3044 return true; 3045 3046 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS 3047 && MEM_VOLATILE_P (PATTERN (insn))) 3048 || (GET_CODE (PATTERN (insn)) == PARALLEL 3049 && asm_noperands (insn) != -1 3050 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0))) 3051 || GET_CODE (PATTERN (insn)) == ASM_INPUT); 3052 } 3053 3054 /* Add fake edges to the function exit for any non constant and non noreturn 3055 calls, volatile inline assembly in the bitmap of blocks specified by 3056 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks 3057 that were split. 3058 3059 The goal is to expose cases in which entering a basic block does not imply 3060 that all subsequent instructions must be executed. */ 3061 3062 static int 3063 rtl_flow_call_edges_add (sbitmap blocks) 3064 { 3065 int i; 3066 int blocks_split = 0; 3067 int last_bb = last_basic_block; 3068 bool check_last_block = false; 3069 3070 if (n_basic_blocks == NUM_FIXED_BLOCKS) 3071 return 0; 3072 3073 if (! blocks) 3074 check_last_block = true; 3075 else 3076 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index); 3077 3078 /* In the last basic block, before epilogue generation, there will be 3079 a fallthru edge to EXIT. Special care is required if the last insn 3080 of the last basic block is a call because make_edge folds duplicate 3081 edges, which would result in the fallthru edge also being marked 3082 fake, which would result in the fallthru edge being removed by 3083 remove_fake_edges, which would result in an invalid CFG. 3084 3085 Moreover, we can't elide the outgoing fake edge, since the block 3086 profiler needs to take this into account in order to solve the minimal 3087 spanning tree in the case that the call doesn't return. 3088 3089 Handle this by adding a dummy instruction in a new last basic block. */ 3090 if (check_last_block) 3091 { 3092 basic_block bb = EXIT_BLOCK_PTR->prev_bb; 3093 rtx insn = BB_END (bb); 3094 3095 /* Back up past insns that must be kept in the same block as a call. */ 3096 while (insn != BB_HEAD (bb) 3097 && keep_with_call_p (insn)) 3098 insn = PREV_INSN (insn); 3099 3100 if (need_fake_edge_p (insn)) 3101 { 3102 edge e; 3103 3104 e = find_edge (bb, EXIT_BLOCK_PTR); 3105 if (e) 3106 { 3107 insert_insn_on_edge (gen_use (const0_rtx), e); 3108 commit_edge_insertions (); 3109 } 3110 } 3111 } 3112 3113 /* Now add fake edges to the function exit for any non constant 3114 calls since there is no way that we can determine if they will 3115 return or not... */ 3116 3117 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++) 3118 { 3119 basic_block bb = BASIC_BLOCK (i); 3120 rtx insn; 3121 rtx prev_insn; 3122 3123 if (!bb) 3124 continue; 3125 3126 if (blocks && !TEST_BIT (blocks, i)) 3127 continue; 3128 3129 for (insn = BB_END (bb); ; insn = prev_insn) 3130 { 3131 prev_insn = PREV_INSN (insn); 3132 if (need_fake_edge_p (insn)) 3133 { 3134 edge e; 3135 rtx split_at_insn = insn; 3136 3137 /* Don't split the block between a call and an insn that should 3138 remain in the same block as the call. */ 3139 if (CALL_P (insn)) 3140 while (split_at_insn != BB_END (bb) 3141 && keep_with_call_p (NEXT_INSN (split_at_insn))) 3142 split_at_insn = NEXT_INSN (split_at_insn); 3143 3144 /* The handling above of the final block before the epilogue 3145 should be enough to verify that there is no edge to the exit 3146 block in CFG already. Calling make_edge in such case would 3147 cause us to mark that edge as fake and remove it later. */ 3148 3149 #ifdef ENABLE_CHECKING 3150 if (split_at_insn == BB_END (bb)) 3151 { 3152 e = find_edge (bb, EXIT_BLOCK_PTR); 3153 gcc_assert (e == NULL); 3154 } 3155 #endif 3156 3157 /* Note that the following may create a new basic block 3158 and renumber the existing basic blocks. */ 3159 if (split_at_insn != BB_END (bb)) 3160 { 3161 e = split_block (bb, split_at_insn); 3162 if (e) 3163 blocks_split++; 3164 } 3165 3166 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); 3167 } 3168 3169 if (insn == BB_HEAD (bb)) 3170 break; 3171 } 3172 } 3173 3174 if (blocks_split) 3175 verify_flow_info (); 3176 3177 return blocks_split; 3178 } 3179 3180 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is 3181 the conditional branch target, SECOND_HEAD should be the fall-thru 3182 there is no need to handle this here the loop versioning code handles 3183 this. the reason for SECON_HEAD is that it is needed for condition 3184 in trees, and this should be of the same type since it is a hook. */ 3185 static void 3186 rtl_lv_add_condition_to_bb (basic_block first_head , 3187 basic_block second_head ATTRIBUTE_UNUSED, 3188 basic_block cond_bb, void *comp_rtx) 3189 { 3190 rtx label, seq, jump; 3191 rtx op0 = XEXP ((rtx)comp_rtx, 0); 3192 rtx op1 = XEXP ((rtx)comp_rtx, 1); 3193 enum rtx_code comp = GET_CODE ((rtx)comp_rtx); 3194 enum machine_mode mode; 3195 3196 3197 label = block_label (first_head); 3198 mode = GET_MODE (op0); 3199 if (mode == VOIDmode) 3200 mode = GET_MODE (op1); 3201 3202 start_sequence (); 3203 op0 = force_operand (op0, NULL_RTX); 3204 op1 = force_operand (op1, NULL_RTX); 3205 do_compare_rtx_and_jump (op0, op1, comp, 0, 3206 mode, NULL_RTX, NULL_RTX, label, -1); 3207 jump = get_last_insn (); 3208 JUMP_LABEL (jump) = label; 3209 LABEL_NUSES (label)++; 3210 seq = get_insns (); 3211 end_sequence (); 3212 3213 /* Add the new cond , in the new head. */ 3214 emit_insn_after(seq, BB_END(cond_bb)); 3215 } 3216 3217 3218 /* Given a block B with unconditional branch at its end, get the 3219 store the return the branch edge and the fall-thru edge in 3220 BRANCH_EDGE and FALLTHRU_EDGE respectively. */ 3221 static void 3222 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge, 3223 edge *fallthru_edge) 3224 { 3225 edge e = EDGE_SUCC (b, 0); 3226 3227 if (e->flags & EDGE_FALLTHRU) 3228 { 3229 *fallthru_edge = e; 3230 *branch_edge = EDGE_SUCC (b, 1); 3231 } 3232 else 3233 { 3234 *branch_edge = e; 3235 *fallthru_edge = EDGE_SUCC (b, 1); 3236 } 3237 } 3238 3239 void 3240 init_rtl_bb_info (basic_block bb) 3241 { 3242 gcc_assert (!bb->il.rtl); 3243 bb->il.rtl = ggc_alloc_cleared_rtl_bb_info (); 3244 } 3245 3246 /* Returns true if it is possible to remove edge E by redirecting 3247 it to the destination of the other edge from E->src. */ 3248 3249 static bool 3250 rtl_can_remove_branch_p (const_edge e) 3251 { 3252 const_basic_block src = e->src; 3253 const_basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest; 3254 const_rtx insn = BB_END (src), set; 3255 3256 /* The conditions are taken from try_redirect_by_replacing_jump. */ 3257 if (target == EXIT_BLOCK_PTR) 3258 return false; 3259 3260 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) 3261 return false; 3262 3263 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX) 3264 || BB_PARTITION (src) != BB_PARTITION (target)) 3265 return false; 3266 3267 if (!onlyjump_p (insn) 3268 || tablejump_p (insn, NULL, NULL)) 3269 return false; 3270 3271 set = single_set (insn); 3272 if (!set || side_effects_p (set)) 3273 return false; 3274 3275 return true; 3276 } 3277 3278 /* We do not want to declare these functions in a header file, since they 3279 should only be used through the cfghooks interface, and we do not want to 3280 move them here since it would require also moving quite a lot of related 3281 code. They are in cfglayout.c. */ 3282 extern bool cfg_layout_can_duplicate_bb_p (const_basic_block); 3283 extern basic_block cfg_layout_duplicate_bb (basic_block); 3284 3285 static basic_block 3286 rtl_duplicate_bb (basic_block bb) 3287 { 3288 bb = cfg_layout_duplicate_bb (bb); 3289 bb->aux = NULL; 3290 return bb; 3291 } 3292 3293 /* Implementation of CFG manipulation for linearized RTL. */ 3294 struct cfg_hooks rtl_cfg_hooks = { 3295 "rtl", 3296 rtl_verify_flow_info, 3297 rtl_dump_bb, 3298 rtl_create_basic_block, 3299 rtl_redirect_edge_and_branch, 3300 rtl_redirect_edge_and_branch_force, 3301 rtl_can_remove_branch_p, 3302 rtl_delete_block, 3303 rtl_split_block, 3304 rtl_move_block_after, 3305 rtl_can_merge_blocks, /* can_merge_blocks_p */ 3306 rtl_merge_blocks, 3307 rtl_predict_edge, 3308 rtl_predicted_by_p, 3309 cfg_layout_can_duplicate_bb_p, 3310 rtl_duplicate_bb, 3311 rtl_split_edge, 3312 rtl_make_forwarder_block, 3313 rtl_tidy_fallthru_edge, 3314 rtl_force_nonfallthru, 3315 rtl_block_ends_with_call_p, 3316 rtl_block_ends_with_condjump_p, 3317 rtl_flow_call_edges_add, 3318 NULL, /* execute_on_growing_pred */ 3319 NULL, /* execute_on_shrinking_pred */ 3320 NULL, /* duplicate loop for trees */ 3321 NULL, /* lv_add_condition_to_bb */ 3322 NULL, /* lv_adjust_loop_header_phi*/ 3323 NULL, /* extract_cond_bb_edges */ 3324 NULL /* flush_pending_stmts */ 3325 }; 3326 3327 /* Implementation of CFG manipulation for cfg layout RTL, where 3328 basic block connected via fallthru edges does not have to be adjacent. 3329 This representation will hopefully become the default one in future 3330 version of the compiler. */ 3331 3332 struct cfg_hooks cfg_layout_rtl_cfg_hooks = { 3333 "cfglayout mode", 3334 rtl_verify_flow_info_1, 3335 rtl_dump_bb, 3336 cfg_layout_create_basic_block, 3337 cfg_layout_redirect_edge_and_branch, 3338 cfg_layout_redirect_edge_and_branch_force, 3339 rtl_can_remove_branch_p, 3340 cfg_layout_delete_block, 3341 cfg_layout_split_block, 3342 rtl_move_block_after, 3343 cfg_layout_can_merge_blocks_p, 3344 cfg_layout_merge_blocks, 3345 rtl_predict_edge, 3346 rtl_predicted_by_p, 3347 cfg_layout_can_duplicate_bb_p, 3348 cfg_layout_duplicate_bb, 3349 cfg_layout_split_edge, 3350 rtl_make_forwarder_block, 3351 NULL, /* tidy_fallthru_edge */ 3352 rtl_force_nonfallthru, 3353 rtl_block_ends_with_call_p, 3354 rtl_block_ends_with_condjump_p, 3355 rtl_flow_call_edges_add, 3356 NULL, /* execute_on_growing_pred */ 3357 NULL, /* execute_on_shrinking_pred */ 3358 duplicate_loop_to_header_edge, /* duplicate loop for trees */ 3359 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */ 3360 NULL, /* lv_adjust_loop_header_phi*/ 3361 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */ 3362 NULL /* flush_pending_stmts */ 3363 }; 3364