1 /* Define control flow data structures for the CFG.
2 Copyright (C) 1987-2024 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 #ifndef GCC_BASIC_BLOCK_H
21 #define GCC_BASIC_BLOCK_H
23 #include <profile-count.h>
25 /* Control flow edge information. */
26 class GTY((user
)) edge_def
{
28 /* The two blocks at the ends of the edge. */
32 /* Instructions queued on the edge. */
33 union edge_def_insns
{
38 /* Auxiliary info specific to a pass. */
41 /* Location of any goto implicit in the edge. */
42 location_t goto_locus
;
44 /* The index number corresponding to this edge in the edge vector
46 unsigned int dest_idx
;
48 int flags
; /* see cfg-flags.def */
49 profile_probability probability
;
51 /* Return count of edge E. */
52 inline profile_count
count () const;
55 /* Masks for edge.flags. */
56 #define DEF_EDGE_FLAG(NAME,IDX) EDGE_##NAME = 1 << IDX ,
58 #include "cfg-flags.def"
59 LAST_CFG_EDGE_FLAG
/* this is only used for EDGE_ALL_FLAGS */
63 /* Bit mask for all edge flags. */
64 #define EDGE_ALL_FLAGS ((LAST_CFG_EDGE_FLAG - 1) * 2 - 1)
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)
72 struct GTY(()) rtl_bb_info
{
73 /* The first insn of the block is embedded into bb->il.x. */
74 /* The last insn of the block. */
77 /* In CFGlayout mode points to insn notes/jumptables to be placed just before
78 and after the block. */
83 struct GTY(()) gimple_bb_info
{
84 /* Sequence of statements in this block. */
87 /* PHI nodes for this block. */
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.
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.
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.
109 A basic block beginning with two labels cannot have notes between
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
116 /* Basic block information indexed by block number. */
117 struct 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
;
122 /* Auxiliary info specific to a pass. */
123 void *GTY ((skip (""))) aux
;
125 /* Innermost loop containing the block. */
126 class loop
*loop_father
;
128 /* The dominance and postdominance information node. */
129 struct et_node
* GTY ((skip (""))) dom
[2];
131 /* Previous and next blocks in the chain. */
135 union basic_block_il_dependent
{
136 struct gimple_bb_info
GTY ((tag ("0"))) gimple
;
139 struct rtl_bb_info
* rtl
;
140 } GTY ((tag ("1"))) x
;
141 } GTY ((desc ("((%1.flags & BB_RTL) != 0)"))) il
;
143 /* Various flags. See cfg-flags.def. */
146 /* The index of this block. */
149 /* Expected number of executions: calculated in profile.cc. */
153 /* This ensures that struct gimple_bb_info is smaller than
154 struct rtl_bb_info, so that inlining the former into basic_block_def
155 is the better choice. */
156 STATIC_ASSERT (sizeof (rtl_bb_info
) >= sizeof (gimple_bb_info
));
158 #define BB_FREQ_MAX 10000
160 /* Masks for basic_block.flags. */
161 #define DEF_BASIC_BLOCK_FLAG(NAME,IDX) BB_##NAME = 1 << IDX ,
164 #include "cfg-flags.def"
165 LAST_CFG_BB_FLAG
/* this is only used for BB_ALL_FLAGS */
167 #undef DEF_BASIC_BLOCK_FLAG
169 /* Bit mask for all basic block flags. */
170 #define BB_ALL_FLAGS ((LAST_CFG_BB_FLAG - 1) * 2 - 1)
172 /* Bit mask for all basic block flags that must be preserved. These are
173 the bit masks that are *not* cleared by clear_bb_flags. */
174 #define BB_FLAGS_TO_PRESERVE \
175 (BB_DISABLE_SCHEDULE | BB_RTL | BB_NON_LOCAL_GOTO_TARGET \
176 | BB_HOT_PARTITION | BB_COLD_PARTITION)
178 /* Dummy bitmask for convenience in the hot/cold partitioning code. */
179 #define BB_UNPARTITIONED 0
181 /* Partitions, to be used when partitioning hot and cold basic blocks into
182 separate sections. */
183 #define BB_PARTITION(bb) ((bb)->flags & (BB_HOT_PARTITION|BB_COLD_PARTITION))
184 #define BB_SET_PARTITION(bb, part) do { \
185 basic_block bb_ = (bb); \
186 bb_->flags = ((bb_->flags & ~(BB_HOT_PARTITION|BB_COLD_PARTITION)) \
190 #define BB_COPY_PARTITION(dstbb, srcbb) \
191 BB_SET_PARTITION (dstbb, BB_PARTITION (srcbb))
193 /* Defines for accessing the fields of the CFG structure for function FN. */
194 #define ENTRY_BLOCK_PTR_FOR_FN(FN) ((FN)->cfg->x_entry_block_ptr)
195 #define EXIT_BLOCK_PTR_FOR_FN(FN) ((FN)->cfg->x_exit_block_ptr)
196 #define basic_block_info_for_fn(FN) ((FN)->cfg->x_basic_block_info)
197 #define n_basic_blocks_for_fn(FN) ((FN)->cfg->x_n_basic_blocks)
198 #define n_edges_for_fn(FN) ((FN)->cfg->x_n_edges)
199 #define last_basic_block_for_fn(FN) ((FN)->cfg->x_last_basic_block)
200 #define label_to_block_map_for_fn(FN) ((FN)->cfg->x_label_to_block_map)
201 #define profile_status_for_fn(FN) ((FN)->cfg->x_profile_status)
203 #define BASIC_BLOCK_FOR_FN(FN,N) \
204 ((*basic_block_info_for_fn (FN))[(N)])
205 #define SET_BASIC_BLOCK_FOR_FN(FN,N,BB) \
206 ((*basic_block_info_for_fn (FN))[(N)] = (BB))
208 /* For iterating over basic blocks. */
209 #define FOR_BB_BETWEEN(BB, FROM, TO, DIR) \
210 for (BB = FROM; BB != TO; BB = BB->DIR)
212 #define FOR_EACH_BB_FN(BB, FN) \
213 FOR_BB_BETWEEN (BB, (FN)->cfg->x_entry_block_ptr->next_bb, (FN)->cfg->x_exit_block_ptr, next_bb)
215 #define FOR_EACH_BB_REVERSE_FN(BB, FN) \
216 FOR_BB_BETWEEN (BB, (FN)->cfg->x_exit_block_ptr->prev_bb, (FN)->cfg->x_entry_block_ptr, prev_bb)
218 /* For iterating over insns in basic block. */
219 #define FOR_BB_INSNS(BB, INSN) \
220 for ((INSN) = BB_HEAD (BB); \
221 (INSN) && (INSN) != NEXT_INSN (BB_END (BB)); \
222 (INSN) = NEXT_INSN (INSN))
224 /* For iterating over insns in basic block when we might remove the
226 #define FOR_BB_INSNS_SAFE(BB, INSN, CURR) \
227 for ((INSN) = BB_HEAD (BB), (CURR) = (INSN) ? NEXT_INSN ((INSN)): NULL; \
228 (INSN) && (INSN) != NEXT_INSN (BB_END (BB)); \
229 (INSN) = (CURR), (CURR) = (INSN) ? NEXT_INSN ((INSN)) : NULL)
231 #define FOR_BB_INSNS_REVERSE(BB, INSN) \
232 for ((INSN) = BB_END (BB); \
233 (INSN) && (INSN) != PREV_INSN (BB_HEAD (BB)); \
234 (INSN) = PREV_INSN (INSN))
236 #define FOR_BB_INSNS_REVERSE_SAFE(BB, INSN, CURR) \
237 for ((INSN) = BB_END (BB),(CURR) = (INSN) ? PREV_INSN ((INSN)) : NULL; \
238 (INSN) && (INSN) != PREV_INSN (BB_HEAD (BB)); \
239 (INSN) = (CURR), (CURR) = (INSN) ? PREV_INSN ((INSN)) : NULL)
241 /* Cycles through _all_ basic blocks, even the fake ones (entry and
244 #define FOR_ALL_BB_FN(BB, FN) \
245 for (BB = ENTRY_BLOCK_PTR_FOR_FN (FN); BB; BB = BB->next_bb)
248 /* Stuff for recording basic block info. */
250 /* For now, these will be functions (so that they can include checked casts
251 to rtx_insn. Once the underlying fields are converted from rtx
252 to rtx_insn, these can be converted back to macros. */
254 #define BB_HEAD(B) (B)->il.x.head_
255 #define BB_END(B) (B)->il.x.rtl->end_
256 #define BB_HEADER(B) (B)->il.x.rtl->header_
257 #define BB_FOOTER(B) (B)->il.x.rtl->footer_
259 /* Special block numbers [markers] for entry and exit.
260 Neither of them is supposed to hold actual statements. */
261 #define ENTRY_BLOCK (0)
262 #define EXIT_BLOCK (1)
264 /* The two blocks that are always in the cfg. */
265 #define NUM_FIXED_BLOCKS (2)
267 /* This is the value which indicates no edge is present. */
268 #define EDGE_INDEX_NO_EDGE -1
270 /* EDGE_INDEX returns an integer index for an edge, or EDGE_INDEX_NO_EDGE
271 if there is no edge between the 2 basic blocks. */
272 #define EDGE_INDEX(el, pred, succ) (find_edge_index ((el), (pred), (succ)))
274 /* INDEX_EDGE_PRED_BB and INDEX_EDGE_SUCC_BB return a pointer to the basic
275 block which is either the pred or succ end of the indexed edge. */
276 #define INDEX_EDGE_PRED_BB(el, index) ((el)->index_to_edge[(index)]->src)
277 #define INDEX_EDGE_SUCC_BB(el, index) ((el)->index_to_edge[(index)]->dest)
279 /* INDEX_EDGE returns a pointer to the edge. */
280 #define INDEX_EDGE(el, index) ((el)->index_to_edge[(index)])
282 /* Number of edges in the compressed edge list. */
283 #define NUM_EDGES(el) ((el)->num_edges)
285 /* BB is assumed to contain conditional jump. Return the fallthru edge. */
286 #define FALLTHRU_EDGE(bb) (EDGE_SUCC ((bb), 0)->flags & EDGE_FALLTHRU \
287 ? EDGE_SUCC ((bb), 0) : EDGE_SUCC ((bb), 1))
289 /* BB is assumed to contain conditional jump. Return the branch edge. */
290 #define BRANCH_EDGE(bb) (EDGE_SUCC ((bb), 0)->flags & EDGE_FALLTHRU \
291 ? EDGE_SUCC ((bb), 1) : EDGE_SUCC ((bb), 0))
293 /* Return expected execution frequency of the edge E. */
294 #define EDGE_FREQUENCY(e) e->count ().to_frequency (cfun)
296 /* Compute a scale factor (or probability) suitable for scaling of
297 gcov_type values via apply_probability() and apply_scale(). */
298 #define GCOV_COMPUTE_SCALE(num,den) \
299 ((den) ? RDIV ((num) * REG_BR_PROB_BASE, (den)) : REG_BR_PROB_BASE)
301 /* Return nonzero if edge is critical. */
302 #define EDGE_CRITICAL_P(e) (EDGE_COUNT ((e)->src->succs) >= 2 \
303 && EDGE_COUNT ((e)->dest->preds) >= 2)
305 #define EDGE_COUNT(ev) vec_safe_length (ev)
306 #define EDGE_I(ev,i) (*ev)[(i)]
307 #define EDGE_PRED(bb,i) (*(bb)->preds)[(i)]
308 #define EDGE_SUCC(bb,i) (*(bb)->succs)[(i)]
310 /* Returns true if BB has precisely one successor. */
313 single_succ_p (const_basic_block bb
)
315 return EDGE_COUNT (bb
->succs
) == 1;
318 /* Returns true if BB has precisely one predecessor. */
321 single_pred_p (const_basic_block bb
)
323 return EDGE_COUNT (bb
->preds
) == 1;
326 /* Returns the single successor edge of basic block BB. Aborts if
327 BB does not have exactly one successor. */
330 single_succ_edge (const_basic_block bb
)
332 gcc_checking_assert (single_succ_p (bb
));
333 return EDGE_SUCC (bb
, 0);
336 /* Returns the single predecessor edge of basic block BB. Aborts
337 if BB does not have exactly one predecessor. */
340 single_pred_edge (const_basic_block bb
)
342 gcc_checking_assert (single_pred_p (bb
));
343 return EDGE_PRED (bb
, 0);
346 /* Returns the single successor block of basic block BB. Aborts
347 if BB does not have exactly one successor. */
350 single_succ (const_basic_block bb
)
352 return single_succ_edge (bb
)->dest
;
355 /* Returns the single predecessor block of basic block BB. Aborts
356 if BB does not have exactly one predecessor.*/
359 single_pred (const_basic_block bb
)
361 return single_pred_edge (bb
)->src
;
364 /* Iterator object for edges. */
366 struct edge_iterator
{
368 vec
<edge
, va_gc
> **container
;
371 inline vec
<edge
, va_gc
> *
372 ei_container (edge_iterator i
)
374 gcc_checking_assert (i
.container
);
378 #define ei_start(iter) ei_start_1 (&(iter))
379 #define ei_last(iter) ei_last_1 (&(iter))
381 /* Return an iterator pointing to the start of an edge vector. */
383 ei_start_1 (vec
<edge
, va_gc
> **ev
)
393 /* Return an iterator pointing to the last element of an edge
396 ei_last_1 (vec
<edge
, va_gc
> **ev
)
400 i
.index
= EDGE_COUNT (*ev
) - 1;
406 /* Is the iterator `i' at the end of the sequence? */
408 ei_end_p (edge_iterator i
)
410 return (i
.index
== EDGE_COUNT (ei_container (i
)));
413 /* Is the iterator `i' at one position before the end of the
416 ei_one_before_end_p (edge_iterator i
)
418 return (i
.index
+ 1 == EDGE_COUNT (ei_container (i
)));
421 /* Advance the iterator to the next element. */
423 ei_next (edge_iterator
*i
)
425 gcc_checking_assert (i
->index
< EDGE_COUNT (ei_container (*i
)));
429 /* Move the iterator to the previous element. */
431 ei_prev (edge_iterator
*i
)
433 gcc_checking_assert (i
->index
> 0);
437 /* Return the edge pointed to by the iterator `i'. */
439 ei_edge (edge_iterator i
)
441 return EDGE_I (ei_container (i
), i
.index
);
444 /* Return an edge pointed to by the iterator. Do it safely so that
445 NULL is returned when the iterator is pointing at the end of the
448 ei_safe_edge (edge_iterator i
)
450 return !ei_end_p (i
) ? ei_edge (i
) : NULL
;
453 /* Return 1 if we should continue to iterate. Return 0 otherwise.
454 *Edge P is set to the next edge if we are to continue to iterate
455 and NULL otherwise. */
458 ei_cond (edge_iterator ei
, edge
*p
)
472 /* This macro serves as a convenient way to iterate each edge in a
473 vector of predecessor or successor edges. It must not be used when
474 an element might be removed during the traversal, otherwise
475 elements will be missed. Instead, use a for-loop like that shown
476 in the following pseudo-code:
478 FOR (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
487 #define FOR_EACH_EDGE(EDGE,ITER,EDGE_VEC) \
488 for ((ITER) = ei_start ((EDGE_VEC)); \
489 ei_cond ((ITER), &(EDGE)); \
492 #define CLEANUP_EXPENSIVE 1 /* Do relatively expensive optimizations
493 except for edge forwarding */
494 #define CLEANUP_CROSSJUMP 2 /* Do crossjumping. */
495 #define CLEANUP_POST_REGSTACK 4 /* We run after reg-stack and need
496 to care REG_DEAD notes. */
497 #define CLEANUP_THREADING 8 /* Do jump threading. */
498 #define CLEANUP_NO_INSN_DEL 16 /* Do not try to delete trivially dead
500 #define CLEANUP_CFGLAYOUT 32 /* Do cleanup in cfglayout mode. */
501 #define CLEANUP_CFG_CHANGED 64 /* The caller changed the CFG. */
502 #define CLEANUP_NO_PARTITIONING 128 /* Do not try to fix partitions. */
503 #define CLEANUP_FORCE_FAST_DCE 0x100 /* Force run_fast_dce to be called
506 /* Return true if BB is in a transaction. */
509 bb_in_transaction (basic_block bb
)
511 return bb
->flags
& BB_IN_TRANSACTION
;
514 /* Return true when one of the predecessor edges of BB is marked with EDGE_EH. */
516 bb_has_eh_pred (basic_block bb
)
521 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
523 if (e
->flags
& EDGE_EH
)
529 /* Return true when one of the predecessor edges of BB is marked with EDGE_ABNORMAL. */
531 bb_has_abnormal_pred (basic_block bb
)
536 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
538 if (e
->flags
& EDGE_ABNORMAL
)
544 /* Return the fallthru edge in EDGES if it exists, NULL otherwise. */
546 find_fallthru_edge (vec
<edge
, va_gc
> *edges
)
551 FOR_EACH_EDGE (e
, ei
, edges
)
552 if (e
->flags
& EDGE_FALLTHRU
)
558 /* Check tha probability is sane. */
561 check_probability (int prob
)
563 gcc_checking_assert (prob
>= 0 && prob
<= REG_BR_PROB_BASE
);
566 /* Given PROB1 and PROB2, return PROB1*PROB2/REG_BR_PROB_BASE.
567 Used to combine BB probabilities. */
570 combine_probabilities (int prob1
, int prob2
)
572 check_probability (prob1
);
573 check_probability (prob2
);
574 return RDIV (prob1
* prob2
, REG_BR_PROB_BASE
);
577 /* Apply scale factor SCALE on frequency or count FREQ. Use this
578 interface when potentially scaling up, so that SCALE is not
579 constrained to be < REG_BR_PROB_BASE. */
582 apply_scale (gcov_type freq
, gcov_type scale
)
584 return RDIV (freq
* scale
, REG_BR_PROB_BASE
);
587 /* Apply probability PROB on frequency or count FREQ. */
590 apply_probability (gcov_type freq
, int prob
)
592 check_probability (prob
);
593 return apply_scale (freq
, prob
);
596 /* Return inverse probability for PROB. */
599 inverse_probability (int prob1
)
601 check_probability (prob1
);
602 return REG_BR_PROB_BASE
- prob1
;
605 /* Return true if BB has at least one abnormal outgoing edge. */
608 has_abnormal_or_eh_outgoing_edge_p (basic_block bb
)
613 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
614 if (e
->flags
& (EDGE_ABNORMAL
| EDGE_EH
))
620 /* Return true when one of the predecessor edges of BB is marked with
621 EDGE_ABNORMAL_CALL or EDGE_EH. */
624 has_abnormal_call_or_eh_pred_edge_p (basic_block bb
)
629 FOR_EACH_EDGE (e
, ei
, bb
->preds
)
630 if (e
->flags
& (EDGE_ABNORMAL_CALL
| EDGE_EH
))
636 /* Return count of edge E. */
637 inline profile_count
edge_def::count () const
639 return src
->count
.apply_probability (probability
);
642 #endif /* GCC_BASIC_BLOCK_H */