1/* Define control flow data structures for the CFG. 2 Copyright (C) 1987-2020 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify it under 7the terms of the GNU General Public License as published by the Free 8Software Foundation; either version 3, or (at your option) any later 9version. 10 11GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12WARRANTY; without even the implied warranty of MERCHANTABILITY or 13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14for more details. 15 16You should have received a copy of the GNU General Public License 17along with GCC; see the file COPYING3. If not see 18<http://www.gnu.org/licenses/>. */ 19 20#ifndef GCC_BASIC_BLOCK_H 21#define GCC_BASIC_BLOCK_H 22 23#include <profile-count.h> 24 25/* Control flow edge information. */ 26class GTY((user)) edge_def { 27public: 28 /* The two blocks at the ends of the edge. */ 29 basic_block src; 30 basic_block dest; 31 32 /* Instructions queued on the edge. */ 33 union edge_def_insns { 34 gimple_seq g; 35 rtx_insn *r; 36 } insns; 37 38 /* Auxiliary info specific to a pass. */ 39 PTR aux; 40 41 /* Location of any goto implicit in the edge. */ 42 location_t goto_locus; 43 44 /* The index number corresponding to this edge in the edge vector 45 dest->preds. */ 46 unsigned int dest_idx; 47 48 int flags; /* see cfg-flags.def */ 49 profile_probability probability; 50 51 /* Return count of edge E. */ 52 inline profile_count count () const; 53}; 54 55/* Masks for edge.flags. */ 56#define DEF_EDGE_FLAG(NAME,IDX) EDGE_##NAME = 1 << IDX , 57enum cfg_edge_flags { 58#include "cfg-flags.def" 59 LAST_CFG_EDGE_FLAG /* this is only used for EDGE_ALL_FLAGS */ 60}; 61#undef DEF_EDGE_FLAG 62 63/* Bit mask for all edge flags. */ 64#define EDGE_ALL_FLAGS ((LAST_CFG_EDGE_FLAG - 1) * 2 - 1) 65 66/* The following four flags all indicate something special about an edge. 67 Test the edge flags on EDGE_COMPLEX to detect all forms of "strange" 68 control flow transfers. */ 69#define EDGE_COMPLEX \ 70 (EDGE_ABNORMAL | EDGE_ABNORMAL_CALL | EDGE_EH | EDGE_PRESERVE) 71 72struct GTY(()) rtl_bb_info { 73 /* The first insn of the block is embedded into bb->il.x. */ 74 /* The last insn of the block. */ 75 rtx_insn *end_; 76 77 /* In CFGlayout mode points to insn notes/jumptables to be placed just before 78 and after the block. */ 79 rtx_insn *header_; 80 rtx_insn *footer_; 81}; 82 83struct GTY(()) gimple_bb_info { 84 /* Sequence of statements in this block. */ 85 gimple_seq seq; 86 87 /* PHI nodes for this block. */ 88 gimple_seq phi_nodes; 89}; 90 91/* A basic block is a sequence of instructions with only one entry and 92 only one exit. If any one of the instructions are executed, they 93 will all be executed, and in sequence from first to last. 94 95 There may be COND_EXEC instructions in the basic block. The 96 COND_EXEC *instructions* will be executed -- but if the condition 97 is false the conditionally executed *expressions* will of course 98 not be executed. We don't consider the conditionally executed 99 expression (which might have side-effects) to be in a separate 100 basic block because the program counter will always be at the same 101 location after the COND_EXEC instruction, regardless of whether the 102 condition is true or not. 103 104 Basic blocks need not start with a label nor end with a jump insn. 105 For example, a previous basic block may just "conditionally fall" 106 into the succeeding basic block, and the last basic block need not 107 end with a jump insn. Block 0 is a descendant of the entry block. 108 109 A basic block beginning with two labels cannot have notes between 110 the labels. 111 112 Data for jump tables are stored in jump_insns that occur in no 113 basic block even though these insns can follow or precede insns in 114 basic blocks. */ 115 116/* Basic block information indexed by block number. */ 117struct GTY((chain_next ("%h.next_bb"), chain_prev ("%h.prev_bb"))) basic_block_def { 118 /* The edges into and out of the block. */ 119 vec<edge, va_gc> *preds; 120 vec<edge, va_gc> *succs; 121 122 /* Auxiliary info specific to a pass. */ 123 PTR GTY ((skip (""))) aux; 124 125 /* Innermost loop containing the block. */ 126 class loop *loop_father; 127 128 /* The dominance and postdominance information node. */ 129 struct et_node * GTY ((skip (""))) dom[2]; 130 131 /* Previous and next blocks in the chain. */ 132 basic_block prev_bb; 133 basic_block next_bb; 134 135 union basic_block_il_dependent { 136 struct gimple_bb_info GTY ((tag ("0"))) gimple; 137 struct { 138 rtx_insn *head_; 139 struct rtl_bb_info * rtl; 140 } GTY ((tag ("1"))) x; 141 } GTY ((desc ("((%1.flags & BB_RTL) != 0)"))) il; 142 143 /* Various flags. See cfg-flags.def. */ 144 int flags; 145 146 /* The index of this block. */ 147 int index; 148 149 /* Expected number of executions: calculated in profile.c. */ 150 profile_count count; 151 152 /* The discriminator for this block. The discriminator distinguishes 153 among several basic blocks that share a common locus, allowing for 154 more accurate sample-based profiling. */ 155 int discriminator; 156}; 157 158/* This ensures that struct gimple_bb_info is smaller than 159 struct rtl_bb_info, so that inlining the former into basic_block_def 160 is the better choice. */ 161typedef int __assert_gimple_bb_smaller_rtl_bb 162 [(int) sizeof (struct rtl_bb_info) 163 - (int) sizeof (struct gimple_bb_info)]; 164 165 166#define BB_FREQ_MAX 10000 167 168/* Masks for basic_block.flags. */ 169#define DEF_BASIC_BLOCK_FLAG(NAME,IDX) BB_##NAME = 1 << IDX , 170enum cfg_bb_flags 171{ 172#include "cfg-flags.def" 173 LAST_CFG_BB_FLAG /* this is only used for BB_ALL_FLAGS */ 174}; 175#undef DEF_BASIC_BLOCK_FLAG 176 177/* Bit mask for all basic block flags. */ 178#define BB_ALL_FLAGS ((LAST_CFG_BB_FLAG - 1) * 2 - 1) 179 180/* Bit mask for all basic block flags that must be preserved. These are 181 the bit masks that are *not* cleared by clear_bb_flags. */ 182#define BB_FLAGS_TO_PRESERVE \ 183 (BB_DISABLE_SCHEDULE | BB_RTL | BB_NON_LOCAL_GOTO_TARGET \ 184 | BB_HOT_PARTITION | BB_COLD_PARTITION) 185 186/* Dummy bitmask for convenience in the hot/cold partitioning code. */ 187#define BB_UNPARTITIONED 0 188 189/* Partitions, to be used when partitioning hot and cold basic blocks into 190 separate sections. */ 191#define BB_PARTITION(bb) ((bb)->flags & (BB_HOT_PARTITION|BB_COLD_PARTITION)) 192#define BB_SET_PARTITION(bb, part) do { \ 193 basic_block bb_ = (bb); \ 194 bb_->flags = ((bb_->flags & ~(BB_HOT_PARTITION|BB_COLD_PARTITION)) \ 195 | (part)); \ 196} while (0) 197 198#define BB_COPY_PARTITION(dstbb, srcbb) \ 199 BB_SET_PARTITION (dstbb, BB_PARTITION (srcbb)) 200 201/* Defines for accessing the fields of the CFG structure for function FN. */ 202#define ENTRY_BLOCK_PTR_FOR_FN(FN) ((FN)->cfg->x_entry_block_ptr) 203#define EXIT_BLOCK_PTR_FOR_FN(FN) ((FN)->cfg->x_exit_block_ptr) 204#define basic_block_info_for_fn(FN) ((FN)->cfg->x_basic_block_info) 205#define n_basic_blocks_for_fn(FN) ((FN)->cfg->x_n_basic_blocks) 206#define n_edges_for_fn(FN) ((FN)->cfg->x_n_edges) 207#define last_basic_block_for_fn(FN) ((FN)->cfg->x_last_basic_block) 208#define label_to_block_map_for_fn(FN) ((FN)->cfg->x_label_to_block_map) 209#define profile_status_for_fn(FN) ((FN)->cfg->x_profile_status) 210 211#define BASIC_BLOCK_FOR_FN(FN,N) \ 212 ((*basic_block_info_for_fn (FN))[(N)]) 213#define SET_BASIC_BLOCK_FOR_FN(FN,N,BB) \ 214 ((*basic_block_info_for_fn (FN))[(N)] = (BB)) 215 216/* For iterating over basic blocks. */ 217#define FOR_BB_BETWEEN(BB, FROM, TO, DIR) \ 218 for (BB = FROM; BB != TO; BB = BB->DIR) 219 220#define FOR_EACH_BB_FN(BB, FN) \ 221 FOR_BB_BETWEEN (BB, (FN)->cfg->x_entry_block_ptr->next_bb, (FN)->cfg->x_exit_block_ptr, next_bb) 222 223#define FOR_EACH_BB_REVERSE_FN(BB, FN) \ 224 FOR_BB_BETWEEN (BB, (FN)->cfg->x_exit_block_ptr->prev_bb, (FN)->cfg->x_entry_block_ptr, prev_bb) 225 226/* For iterating over insns in basic block. */ 227#define FOR_BB_INSNS(BB, INSN) \ 228 for ((INSN) = BB_HEAD (BB); \ 229 (INSN) && (INSN) != NEXT_INSN (BB_END (BB)); \ 230 (INSN) = NEXT_INSN (INSN)) 231 232/* For iterating over insns in basic block when we might remove the 233 current insn. */ 234#define FOR_BB_INSNS_SAFE(BB, INSN, CURR) \ 235 for ((INSN) = BB_HEAD (BB), (CURR) = (INSN) ? NEXT_INSN ((INSN)): NULL; \ 236 (INSN) && (INSN) != NEXT_INSN (BB_END (BB)); \ 237 (INSN) = (CURR), (CURR) = (INSN) ? NEXT_INSN ((INSN)) : NULL) 238 239#define FOR_BB_INSNS_REVERSE(BB, INSN) \ 240 for ((INSN) = BB_END (BB); \ 241 (INSN) && (INSN) != PREV_INSN (BB_HEAD (BB)); \ 242 (INSN) = PREV_INSN (INSN)) 243 244#define FOR_BB_INSNS_REVERSE_SAFE(BB, INSN, CURR) \ 245 for ((INSN) = BB_END (BB),(CURR) = (INSN) ? PREV_INSN ((INSN)) : NULL; \ 246 (INSN) && (INSN) != PREV_INSN (BB_HEAD (BB)); \ 247 (INSN) = (CURR), (CURR) = (INSN) ? PREV_INSN ((INSN)) : NULL) 248 249/* Cycles through _all_ basic blocks, even the fake ones (entry and 250 exit block). */ 251 252#define FOR_ALL_BB_FN(BB, FN) \ 253 for (BB = ENTRY_BLOCK_PTR_FOR_FN (FN); BB; BB = BB->next_bb) 254 255 256/* Stuff for recording basic block info. */ 257 258/* For now, these will be functions (so that they can include checked casts 259 to rtx_insn. Once the underlying fields are converted from rtx 260 to rtx_insn, these can be converted back to macros. */ 261 262#define BB_HEAD(B) (B)->il.x.head_ 263#define BB_END(B) (B)->il.x.rtl->end_ 264#define BB_HEADER(B) (B)->il.x.rtl->header_ 265#define BB_FOOTER(B) (B)->il.x.rtl->footer_ 266 267/* Special block numbers [markers] for entry and exit. 268 Neither of them is supposed to hold actual statements. */ 269#define ENTRY_BLOCK (0) 270#define EXIT_BLOCK (1) 271 272/* The two blocks that are always in the cfg. */ 273#define NUM_FIXED_BLOCKS (2) 274 275/* This is the value which indicates no edge is present. */ 276#define EDGE_INDEX_NO_EDGE -1 277 278/* EDGE_INDEX returns an integer index for an edge, or EDGE_INDEX_NO_EDGE 279 if there is no edge between the 2 basic blocks. */ 280#define EDGE_INDEX(el, pred, succ) (find_edge_index ((el), (pred), (succ))) 281 282/* INDEX_EDGE_PRED_BB and INDEX_EDGE_SUCC_BB return a pointer to the basic 283 block which is either the pred or succ end of the indexed edge. */ 284#define INDEX_EDGE_PRED_BB(el, index) ((el)->index_to_edge[(index)]->src) 285#define INDEX_EDGE_SUCC_BB(el, index) ((el)->index_to_edge[(index)]->dest) 286 287/* INDEX_EDGE returns a pointer to the edge. */ 288#define INDEX_EDGE(el, index) ((el)->index_to_edge[(index)]) 289 290/* Number of edges in the compressed edge list. */ 291#define NUM_EDGES(el) ((el)->num_edges) 292 293/* BB is assumed to contain conditional jump. Return the fallthru edge. */ 294#define FALLTHRU_EDGE(bb) (EDGE_SUCC ((bb), 0)->flags & EDGE_FALLTHRU \ 295 ? EDGE_SUCC ((bb), 0) : EDGE_SUCC ((bb), 1)) 296 297/* BB is assumed to contain conditional jump. Return the branch edge. */ 298#define BRANCH_EDGE(bb) (EDGE_SUCC ((bb), 0)->flags & EDGE_FALLTHRU \ 299 ? EDGE_SUCC ((bb), 1) : EDGE_SUCC ((bb), 0)) 300 301/* Return expected execution frequency of the edge E. */ 302#define EDGE_FREQUENCY(e) e->count ().to_frequency (cfun) 303 304/* Compute a scale factor (or probability) suitable for scaling of 305 gcov_type values via apply_probability() and apply_scale(). */ 306#define GCOV_COMPUTE_SCALE(num,den) \ 307 ((den) ? RDIV ((num) * REG_BR_PROB_BASE, (den)) : REG_BR_PROB_BASE) 308 309/* Return nonzero if edge is critical. */ 310#define EDGE_CRITICAL_P(e) (EDGE_COUNT ((e)->src->succs) >= 2 \ 311 && EDGE_COUNT ((e)->dest->preds) >= 2) 312 313#define EDGE_COUNT(ev) vec_safe_length (ev) 314#define EDGE_I(ev,i) (*ev)[(i)] 315#define EDGE_PRED(bb,i) (*(bb)->preds)[(i)] 316#define EDGE_SUCC(bb,i) (*(bb)->succs)[(i)] 317 318/* Returns true if BB has precisely one successor. */ 319 320static inline bool 321single_succ_p (const_basic_block bb) 322{ 323 return EDGE_COUNT (bb->succs) == 1; 324} 325 326/* Returns true if BB has precisely one predecessor. */ 327 328static inline bool 329single_pred_p (const_basic_block bb) 330{ 331 return EDGE_COUNT (bb->preds) == 1; 332} 333 334/* Returns the single successor edge of basic block BB. Aborts if 335 BB does not have exactly one successor. */ 336 337static inline edge 338single_succ_edge (const_basic_block bb) 339{ 340 gcc_checking_assert (single_succ_p (bb)); 341 return EDGE_SUCC (bb, 0); 342} 343 344/* Returns the single predecessor edge of basic block BB. Aborts 345 if BB does not have exactly one predecessor. */ 346 347static inline edge 348single_pred_edge (const_basic_block bb) 349{ 350 gcc_checking_assert (single_pred_p (bb)); 351 return EDGE_PRED (bb, 0); 352} 353 354/* Returns the single successor block of basic block BB. Aborts 355 if BB does not have exactly one successor. */ 356 357static inline basic_block 358single_succ (const_basic_block bb) 359{ 360 return single_succ_edge (bb)->dest; 361} 362 363/* Returns the single predecessor block of basic block BB. Aborts 364 if BB does not have exactly one predecessor.*/ 365 366static inline basic_block 367single_pred (const_basic_block bb) 368{ 369 return single_pred_edge (bb)->src; 370} 371 372/* Iterator object for edges. */ 373 374struct edge_iterator { 375 unsigned index; 376 vec<edge, va_gc> **container; 377}; 378 379static inline vec<edge, va_gc> * 380ei_container (edge_iterator i) 381{ 382 gcc_checking_assert (i.container); 383 return *i.container; 384} 385 386#define ei_start(iter) ei_start_1 (&(iter)) 387#define ei_last(iter) ei_last_1 (&(iter)) 388 389/* Return an iterator pointing to the start of an edge vector. */ 390static inline edge_iterator 391ei_start_1 (vec<edge, va_gc> **ev) 392{ 393 edge_iterator i; 394 395 i.index = 0; 396 i.container = ev; 397 398 return i; 399} 400 401/* Return an iterator pointing to the last element of an edge 402 vector. */ 403static inline edge_iterator 404ei_last_1 (vec<edge, va_gc> **ev) 405{ 406 edge_iterator i; 407 408 i.index = EDGE_COUNT (*ev) - 1; 409 i.container = ev; 410 411 return i; 412} 413 414/* Is the iterator `i' at the end of the sequence? */ 415static inline bool 416ei_end_p (edge_iterator i) 417{ 418 return (i.index == EDGE_COUNT (ei_container (i))); 419} 420 421/* Is the iterator `i' at one position before the end of the 422 sequence? */ 423static inline bool 424ei_one_before_end_p (edge_iterator i) 425{ 426 return (i.index + 1 == EDGE_COUNT (ei_container (i))); 427} 428 429/* Advance the iterator to the next element. */ 430static inline void 431ei_next (edge_iterator *i) 432{ 433 gcc_checking_assert (i->index < EDGE_COUNT (ei_container (*i))); 434 i->index++; 435} 436 437/* Move the iterator to the previous element. */ 438static inline void 439ei_prev (edge_iterator *i) 440{ 441 gcc_checking_assert (i->index > 0); 442 i->index--; 443} 444 445/* Return the edge pointed to by the iterator `i'. */ 446static inline edge 447ei_edge (edge_iterator i) 448{ 449 return EDGE_I (ei_container (i), i.index); 450} 451 452/* Return an edge pointed to by the iterator. Do it safely so that 453 NULL is returned when the iterator is pointing at the end of the 454 sequence. */ 455static inline edge 456ei_safe_edge (edge_iterator i) 457{ 458 return !ei_end_p (i) ? ei_edge (i) : NULL; 459} 460 461/* Return 1 if we should continue to iterate. Return 0 otherwise. 462 *Edge P is set to the next edge if we are to continue to iterate 463 and NULL otherwise. */ 464 465static inline bool 466ei_cond (edge_iterator ei, edge *p) 467{ 468 if (!ei_end_p (ei)) 469 { 470 *p = ei_edge (ei); 471 return 1; 472 } 473 else 474 { 475 *p = NULL; 476 return 0; 477 } 478} 479 480/* This macro serves as a convenient way to iterate each edge in a 481 vector of predecessor or successor edges. It must not be used when 482 an element might be removed during the traversal, otherwise 483 elements will be missed. Instead, use a for-loop like that shown 484 in the following pseudo-code: 485 486 FOR (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) 487 { 488 IF (e != taken_edge) 489 remove_edge (e); 490 ELSE 491 ei_next (&ei); 492 } 493*/ 494 495#define FOR_EACH_EDGE(EDGE,ITER,EDGE_VEC) \ 496 for ((ITER) = ei_start ((EDGE_VEC)); \ 497 ei_cond ((ITER), &(EDGE)); \ 498 ei_next (&(ITER))) 499 500#define CLEANUP_EXPENSIVE 1 /* Do relatively expensive optimizations 501 except for edge forwarding */ 502#define CLEANUP_CROSSJUMP 2 /* Do crossjumping. */ 503#define CLEANUP_POST_REGSTACK 4 /* We run after reg-stack and need 504 to care REG_DEAD notes. */ 505#define CLEANUP_THREADING 8 /* Do jump threading. */ 506#define CLEANUP_NO_INSN_DEL 16 /* Do not try to delete trivially dead 507 insns. */ 508#define CLEANUP_CFGLAYOUT 32 /* Do cleanup in cfglayout mode. */ 509#define CLEANUP_CFG_CHANGED 64 /* The caller changed the CFG. */ 510#define CLEANUP_NO_PARTITIONING 128 /* Do not try to fix partitions. */ 511#define CLEANUP_FORCE_FAST_DCE 0x100 /* Force run_fast_dce to be called 512 at least once. */ 513 514/* Return true if BB is in a transaction. */ 515 516static inline bool 517bb_in_transaction (basic_block bb) 518{ 519 return bb->flags & BB_IN_TRANSACTION; 520} 521 522/* Return true when one of the predecessor edges of BB is marked with EDGE_EH. */ 523static inline bool 524bb_has_eh_pred (basic_block bb) 525{ 526 edge e; 527 edge_iterator ei; 528 529 FOR_EACH_EDGE (e, ei, bb->preds) 530 { 531 if (e->flags & EDGE_EH) 532 return true; 533 } 534 return false; 535} 536 537/* Return true when one of the predecessor edges of BB is marked with EDGE_ABNORMAL. */ 538static inline bool 539bb_has_abnormal_pred (basic_block bb) 540{ 541 edge e; 542 edge_iterator ei; 543 544 FOR_EACH_EDGE (e, ei, bb->preds) 545 { 546 if (e->flags & EDGE_ABNORMAL) 547 return true; 548 } 549 return false; 550} 551 552/* Return the fallthru edge in EDGES if it exists, NULL otherwise. */ 553static inline edge 554find_fallthru_edge (vec<edge, va_gc> *edges) 555{ 556 edge e; 557 edge_iterator ei; 558 559 FOR_EACH_EDGE (e, ei, edges) 560 if (e->flags & EDGE_FALLTHRU) 561 break; 562 563 return e; 564} 565 566/* Check tha probability is sane. */ 567 568static inline void 569check_probability (int prob) 570{ 571 gcc_checking_assert (prob >= 0 && prob <= REG_BR_PROB_BASE); 572} 573 574/* Given PROB1 and PROB2, return PROB1*PROB2/REG_BR_PROB_BASE. 575 Used to combine BB probabilities. */ 576 577static inline int 578combine_probabilities (int prob1, int prob2) 579{ 580 check_probability (prob1); 581 check_probability (prob2); 582 return RDIV (prob1 * prob2, REG_BR_PROB_BASE); 583} 584 585/* Apply scale factor SCALE on frequency or count FREQ. Use this 586 interface when potentially scaling up, so that SCALE is not 587 constrained to be < REG_BR_PROB_BASE. */ 588 589static inline gcov_type 590apply_scale (gcov_type freq, gcov_type scale) 591{ 592 return RDIV (freq * scale, REG_BR_PROB_BASE); 593} 594 595/* Apply probability PROB on frequency or count FREQ. */ 596 597static inline gcov_type 598apply_probability (gcov_type freq, int prob) 599{ 600 check_probability (prob); 601 return apply_scale (freq, prob); 602} 603 604/* Return inverse probability for PROB. */ 605 606static inline int 607inverse_probability (int prob1) 608{ 609 check_probability (prob1); 610 return REG_BR_PROB_BASE - prob1; 611} 612 613/* Return true if BB has at least one abnormal outgoing edge. */ 614 615static inline bool 616has_abnormal_or_eh_outgoing_edge_p (basic_block bb) 617{ 618 edge e; 619 edge_iterator ei; 620 621 FOR_EACH_EDGE (e, ei, bb->succs) 622 if (e->flags & (EDGE_ABNORMAL | EDGE_EH)) 623 return true; 624 625 return false; 626} 627 628/* Return true when one of the predecessor edges of BB is marked with 629 EDGE_ABNORMAL_CALL or EDGE_EH. */ 630 631static inline bool 632has_abnormal_call_or_eh_pred_edge_p (basic_block bb) 633{ 634 edge e; 635 edge_iterator ei; 636 637 FOR_EACH_EDGE (e, ei, bb->preds) 638 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)) 639 return true; 640 641 return false; 642} 643 644/* Return count of edge E. */ 645inline profile_count edge_def::count () const 646{ 647 return src->count.apply_probability (probability); 648} 649 650#endif /* GCC_BASIC_BLOCK_H */ 651