1/* Define control flow data structures for the CFG.
2 Copyright (C) 1987-2017 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. */
26struct GTY((user)) edge_def {
27 /* The two blocks at the ends of the edge. */
28 basic_block src;
29 basic_block dest;
30
31 /* Instructions queued on the edge. */
32 union edge_def_insns {
33 gimple_seq g;
34 rtx_insn *r;
35 } insns;
36
37 /* Auxiliary info specific to a pass. */
38 PTR aux;
39
40 /* Location of any goto implicit in the edge. */
41 location_t goto_locus;
42
43 /* The index number corresponding to this edge in the edge vector
44 dest->preds. */
45 unsigned int dest_idx;
46
47 int flags; /* see cfg-flags.def */
48 profile_probability probability;
49
50 /* Return count of edge E. */
51 inline profile_count count () const;
52};
53
54/* Masks for edge.flags. */
55#define DEF_EDGE_FLAG(NAME,IDX) EDGE_##NAME = 1 << IDX ,
56enum cfg_edge_flags {
57#include "cfg-flags.def"
58 LAST_CFG_EDGE_FLAG /* this is only used for EDGE_ALL_FLAGS */
59};
60#undef DEF_EDGE_FLAG
61
62/* Bit mask for all edge flags. */
63#define EDGE_ALL_FLAGS ((LAST_CFG_EDGE_FLAG - 1) * 2 - 1)
64
65/* The following four flags all indicate something special about an edge.
66 Test the edge flags on EDGE_COMPLEX to detect all forms of "strange"
67 control flow transfers. */
68#define EDGE_COMPLEX \
69 (EDGE_ABNORMAL | EDGE_ABNORMAL_CALL | EDGE_EH | EDGE_PRESERVE)
70
71struct GTY(()) rtl_bb_info {
72 /* The first insn of the block is embedded into bb->il.x. */
73 /* The last insn of the block. */
74 rtx_insn *end_;
75
76 /* In CFGlayout mode points to insn notes/jumptables to be placed just before
77 and after the block. */
78 rtx_insn *header_;
79 rtx_insn *footer_;
80};
81
82struct GTY(()) gimple_bb_info {
83 /* Sequence of statements in this block. */
84 gimple_seq seq;
85
86 /* PHI nodes for this block. */
87 gimple_seq phi_nodes;
88};
89
90/* A basic block is a sequence of instructions with only one entry and
91 only one exit. If any one of the instructions are executed, they
92 will all be executed, and in sequence from first to last.
93
94 There may be COND_EXEC instructions in the basic block. The
95 COND_EXEC *instructions* will be executed -- but if the condition
96 is false the conditionally executed *expressions* will of course
97 not be executed. We don't consider the conditionally executed
98 expression (which might have side-effects) to be in a separate
99 basic block because the program counter will always be at the same
100 location after the COND_EXEC instruction, regardless of whether the
101 condition is true or not.
102
103 Basic blocks need not start with a label nor end with a jump insn.
104 For example, a previous basic block may just "conditionally fall"
105 into the succeeding basic block, and the last basic block need not
106 end with a jump insn. Block 0 is a descendant of the entry block.
107
108 A basic block beginning with two labels cannot have notes between
109 the labels.
110
111 Data for jump tables are stored in jump_insns that occur in no
112 basic block even though these insns can follow or precede insns in
113 basic blocks. */
114
115/* Basic block information indexed by block number. */
116struct GTY((chain_next ("%h.next_bb"), chain_prev ("%h.prev_bb"))) basic_block_def {
117 /* The edges into and out of the block. */
118 vec<edge, va_gc> *preds;
119 vec<edge, va_gc> *succs;
120
121 /* Auxiliary info specific to a pass. */
122 PTR GTY ((skip (""))) aux;
123
124 /* Innermost loop containing the block. */
125 struct loop *loop_father;
126
127 /* The dominance and postdominance information node. */
128 struct et_node * GTY ((skip (""))) dom[2];
129
130 /* Previous and next blocks in the chain. */
131 basic_block prev_bb;
132 basic_block next_bb;
133
134 union basic_block_il_dependent {
135 struct gimple_bb_info GTY ((tag ("0"))) gimple;
136 struct {
137 rtx_insn *head_;
138 struct rtl_bb_info * rtl;
139 } GTY ((tag ("1"))) x;
140 } GTY ((desc ("((%1.flags & BB_RTL) != 0)"))) il;
141
142 /* Various flags. See cfg-flags.def. */
143 int flags;
144
145 /* The index of this block. */
146 int index;
147
148 /* Expected number of executions: calculated in profile.c. */
149 profile_count count;
150
151 /* The discriminator for this block. The discriminator distinguishes
152 among several basic blocks that share a common locus, allowing for
153 more accurate sample-based profiling. */
154 int discriminator;
155};
156
157/* This ensures that struct gimple_bb_info is smaller than
158 struct rtl_bb_info, so that inlining the former into basic_block_def
159 is the better choice. */
160typedef int __assert_gimple_bb_smaller_rtl_bb
161 [(int) sizeof (struct rtl_bb_info)
162 - (int) sizeof (struct gimple_bb_info)];
163
164
165#define BB_FREQ_MAX 10000
166
167/* Masks for basic_block.flags. */
168#define DEF_BASIC_BLOCK_FLAG(NAME,IDX) BB_##NAME = 1 << IDX ,
169enum cfg_bb_flags
170{
171#include "cfg-flags.def"
172 LAST_CFG_BB_FLAG /* this is only used for BB_ALL_FLAGS */
173};
174#undef DEF_BASIC_BLOCK_FLAG
175
176/* Bit mask for all basic block flags. */
177#define BB_ALL_FLAGS ((LAST_CFG_BB_FLAG - 1) * 2 - 1)
178
179/* Bit mask for all basic block flags that must be preserved. These are
180 the bit masks that are *not* cleared by clear_bb_flags. */
181#define BB_FLAGS_TO_PRESERVE \
182 (BB_DISABLE_SCHEDULE | BB_RTL | BB_NON_LOCAL_GOTO_TARGET \
183 | BB_HOT_PARTITION | BB_COLD_PARTITION)
184
185/* Dummy bitmask for convenience in the hot/cold partitioning code. */
186#define BB_UNPARTITIONED 0
187
188/* Partitions, to be used when partitioning hot and cold basic blocks into
189 separate sections. */
190#define BB_PARTITION(bb) ((bb)->flags & (BB_HOT_PARTITION|BB_COLD_PARTITION))
191#define BB_SET_PARTITION(bb, part) do { \
192 basic_block bb_ = (bb); \
193 bb_->flags = ((bb_->flags & ~(BB_HOT_PARTITION|BB_COLD_PARTITION)) \
194 | (part)); \
195} while (0)
196
197#define BB_COPY_PARTITION(dstbb, srcbb) \
198 BB_SET_PARTITION (dstbb, BB_PARTITION (srcbb))
199
200/* Defines for accessing the fields of the CFG structure for function FN. */
201#define ENTRY_BLOCK_PTR_FOR_FN(FN) ((FN)->cfg->x_entry_block_ptr)
202#define EXIT_BLOCK_PTR_FOR_FN(FN) ((FN)->cfg->x_exit_block_ptr)
203#define basic_block_info_for_fn(FN) ((FN)->cfg->x_basic_block_info)
204#define n_basic_blocks_for_fn(FN) ((FN)->cfg->x_n_basic_blocks)
205#define n_edges_for_fn(FN) ((FN)->cfg->x_n_edges)
206#define last_basic_block_for_fn(FN) ((FN)->cfg->x_last_basic_block)
207#define label_to_block_map_for_fn(FN) ((FN)->cfg->x_label_to_block_map)
208#define profile_status_for_fn(FN) ((FN)->cfg->x_profile_status)
209
210#define BASIC_BLOCK_FOR_FN(FN,N) \
211 ((*basic_block_info_for_fn (FN))[(N)])
212#define SET_BASIC_BLOCK_FOR_FN(FN,N,BB) \
213 ((*basic_block_info_for_fn (FN))[(N)] = (BB))
214
215/* For iterating over basic blocks. */
216#define FOR_BB_BETWEEN(BB, FROM, TO, DIR) \
217 for (BB = FROM; BB != TO; BB = BB->DIR)
218
219#define FOR_EACH_BB_FN(BB, FN) \
220 FOR_BB_BETWEEN (BB, (FN)->cfg->x_entry_block_ptr->next_bb, (FN)->cfg->x_exit_block_ptr, next_bb)
221
222#define FOR_EACH_BB_REVERSE_FN(BB, FN) \
223 FOR_BB_BETWEEN (BB, (FN)->cfg->x_exit_block_ptr->prev_bb, (FN)->cfg->x_entry_block_ptr, prev_bb)
224
225/* For iterating over insns in basic block. */
226#define FOR_BB_INSNS(BB, INSN) \
227 for ((INSN) = BB_HEAD (BB); \
228 (INSN) && (INSN) != NEXT_INSN (BB_END (BB)); \
229 (INSN) = NEXT_INSN (INSN))
230
231/* For iterating over insns in basic block when we might remove the
232 current insn. */
233#define FOR_BB_INSNS_SAFE(BB, INSN, CURR) \
234 for ((INSN) = BB_HEAD (BB), (CURR) = (INSN) ? NEXT_INSN ((INSN)): NULL; \
235 (INSN) && (INSN) != NEXT_INSN (BB_END (BB)); \
236 (INSN) = (CURR), (CURR) = (INSN) ? NEXT_INSN ((INSN)) : NULL)
237
238#define FOR_BB_INSNS_REVERSE(BB, INSN) \
239 for ((INSN) = BB_END (BB); \
240 (INSN) && (INSN) != PREV_INSN (BB_HEAD (BB)); \
241 (INSN) = PREV_INSN (INSN))
242
243#define FOR_BB_INSNS_REVERSE_SAFE(BB, INSN, CURR) \
244 for ((INSN) = BB_END (BB),(CURR) = (INSN) ? PREV_INSN ((INSN)) : NULL; \
245 (INSN) && (INSN) != PREV_INSN (BB_HEAD (BB)); \
246 (INSN) = (CURR), (CURR) = (INSN) ? PREV_INSN ((INSN)) : NULL)
247
248/* Cycles through _all_ basic blocks, even the fake ones (entry and
249 exit block). */
250
251#define FOR_ALL_BB_FN(BB, FN) \
252 for (BB = ENTRY_BLOCK_PTR_FOR_FN (FN); BB; BB = BB->next_bb)
253
254
255/* Stuff for recording basic block info. */
256
257/* For now, these will be functions (so that they can include checked casts
258 to rtx_insn. Once the underlying fields are converted from rtx
259 to rtx_insn, these can be converted back to macros. */
260
261#define BB_HEAD(B) (B)->il.x.head_
262#define BB_END(B) (B)->il.x.rtl->end_
263#define BB_HEADER(B) (B)->il.x.rtl->header_
264#define BB_FOOTER(B) (B)->il.x.rtl->footer_
265
266/* Special block numbers [markers] for entry and exit.
267 Neither of them is supposed to hold actual statements. */
268#define ENTRY_BLOCK (0)
269#define EXIT_BLOCK (1)
270
271/* The two blocks that are always in the cfg. */
272#define NUM_FIXED_BLOCKS (2)
273
274/* This is the value which indicates no edge is present. */
275#define EDGE_INDEX_NO_EDGE -1
276
277/* EDGE_INDEX returns an integer index for an edge, or EDGE_INDEX_NO_EDGE
278 if there is no edge between the 2 basic blocks. */
279#define EDGE_INDEX(el, pred, succ) (find_edge_index ((el), (pred), (succ)))
280
281/* INDEX_EDGE_PRED_BB and INDEX_EDGE_SUCC_BB return a pointer to the basic
282 block which is either the pred or succ end of the indexed edge. */
283#define INDEX_EDGE_PRED_BB(el, index) ((el)->index_to_edge[(index)]->src)
284#define INDEX_EDGE_SUCC_BB(el, index) ((el)->index_to_edge[(index)]->dest)
285
286/* INDEX_EDGE returns a pointer to the edge. */
287#define INDEX_EDGE(el, index) ((el)->index_to_edge[(index)])
288
289/* Number of edges in the compressed edge list. */
290#define NUM_EDGES(el) ((el)->num_edges)
291
292/* BB is assumed to contain conditional jump. Return the fallthru edge. */
293#define FALLTHRU_EDGE(bb) (EDGE_SUCC ((bb), 0)->flags & EDGE_FALLTHRU \
294 ? EDGE_SUCC ((bb), 0) : EDGE_SUCC ((bb), 1))
295
296/* BB is assumed to contain conditional jump. Return the branch edge. */
297#define BRANCH_EDGE(bb) (EDGE_SUCC ((bb), 0)->flags & EDGE_FALLTHRU \
298 ? EDGE_SUCC ((bb), 1) : EDGE_SUCC ((bb), 0))
299
300/* Return expected execution frequency of the edge E. */
301#define EDGE_FREQUENCY(e) e->count ().to_frequency (cfun)
302
303/* Compute a scale factor (or probability) suitable for scaling of
304 gcov_type values via apply_probability() and apply_scale(). */
305#define GCOV_COMPUTE_SCALE(num,den) \
306 ((den) ? RDIV ((num) * REG_BR_PROB_BASE, (den)) : REG_BR_PROB_BASE)
307
308/* Return nonzero if edge is critical. */
309#define EDGE_CRITICAL_P(e) (EDGE_COUNT ((e)->src->succs) >= 2 \
310 && EDGE_COUNT ((e)->dest->preds) >= 2)
311
312#define EDGE_COUNT(ev) vec_safe_length (ev)
313#define EDGE_I(ev,i) (*ev)[(i)]
314#define EDGE_PRED(bb,i) (*(bb)->preds)[(i)]
315#define EDGE_SUCC(bb,i) (*(bb)->succs)[(i)]
316
317/* Returns true if BB has precisely one successor. */
318
319static inline bool
320single_succ_p (const_basic_block bb)
321{
322 return EDGE_COUNT (bb->succs) == 1;
323}
324
325/* Returns true if BB has precisely one predecessor. */
326
327static inline bool
328single_pred_p (const_basic_block bb)
329{
330 return EDGE_COUNT (bb->preds) == 1;
331}
332
333/* Returns the single successor edge of basic block BB. Aborts if
334 BB does not have exactly one successor. */
335
336static inline edge
337single_succ_edge (const_basic_block bb)
338{
339 gcc_checking_assert (single_succ_p (bb));
340 return EDGE_SUCC (bb, 0);
341}
342
343/* Returns the single predecessor edge of basic block BB. Aborts
344 if BB does not have exactly one predecessor. */
345
346static inline edge
347single_pred_edge (const_basic_block bb)
348{
349 gcc_checking_assert (single_pred_p (bb));
350 return EDGE_PRED (bb, 0);
351}
352
353/* Returns the single successor block of basic block BB. Aborts
354 if BB does not have exactly one successor. */
355
356static inline basic_block
357single_succ (const_basic_block bb)
358{
359 return single_succ_edge (bb)->dest;
360}
361
362/* Returns the single predecessor block of basic block BB. Aborts
363 if BB does not have exactly one predecessor.*/
364
365static inline basic_block
366single_pred (const_basic_block bb)
367{
368 return single_pred_edge (bb)->src;
369}
370
371/* Iterator object for edges. */
372
373struct edge_iterator {
374 unsigned index;
375 vec<edge, va_gc> **container;
376};
377
378static inline vec<edge, va_gc> *
379ei_container (edge_iterator i)
380{
381 gcc_checking_assert (i.container);
382 return *i.container;
383}
384
385#define ei_start(iter) ei_start_1 (&(iter))
386#define ei_last(iter) ei_last_1 (&(iter))
387
388/* Return an iterator pointing to the start of an edge vector. */
389static inline edge_iterator
390ei_start_1 (vec<edge, va_gc> **ev)
391{
392 edge_iterator i;
393
394 i.index = 0;
395 i.container = ev;
396
397 return i;
398}
399
400/* Return an iterator pointing to the last element of an edge
401 vector. */
402static inline edge_iterator
403ei_last_1 (vec<edge, va_gc> **ev)
404{
405 edge_iterator i;
406
407 i.index = EDGE_COUNT (*ev) - 1;
408 i.container = ev;
409
410 return i;
411}
412
413/* Is the iterator `i' at the end of the sequence? */
414static inline bool
415ei_end_p (edge_iterator i)
416{
417 return (i.index == EDGE_COUNT (ei_container (i)));
418}
419
420/* Is the iterator `i' at one position before the end of the
421 sequence? */
422static inline bool
423ei_one_before_end_p (edge_iterator i)
424{
425 return (i.index + 1 == EDGE_COUNT (ei_container (i)));
426}
427
428/* Advance the iterator to the next element. */
429static inline void
430ei_next (edge_iterator *i)
431{
432 gcc_checking_assert (i->index < EDGE_COUNT (ei_container (*i)));
433 i->index++;
434}
435
436/* Move the iterator to the previous element. */
437static inline void
438ei_prev (edge_iterator *i)
439{
440 gcc_checking_assert (i->index > 0);
441 i->index--;
442}
443
444/* Return the edge pointed to by the iterator `i'. */
445static inline edge
446ei_edge (edge_iterator i)
447{
448 return EDGE_I (ei_container (i), i.index);
449}
450
451/* Return an edge pointed to by the iterator. Do it safely so that
452 NULL is returned when the iterator is pointing at the end of the
453 sequence. */
454static inline edge
455ei_safe_edge (edge_iterator i)
456{
457 return !ei_end_p (i) ? ei_edge (i) : NULL;
458}
459
460/* Return 1 if we should continue to iterate. Return 0 otherwise.
461 *Edge P is set to the next edge if we are to continue to iterate
462 and NULL otherwise. */
463
464static inline bool
465ei_cond (edge_iterator ei, edge *p)
466{
467 if (!ei_end_p (ei))
468 {
469 *p = ei_edge (ei);
470 return 1;
471 }
472 else
473 {
474 *p = NULL;
475 return 0;
476 }
477}
478
479/* This macro serves as a convenient way to iterate each edge in a
480 vector of predecessor or successor edges. It must not be used when
481 an element might be removed during the traversal, otherwise
482 elements will be missed. Instead, use a for-loop like that shown
483 in the following pseudo-code:
484
485 FOR (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
486 {
487 IF (e != taken_edge)
488 remove_edge (e);
489 ELSE
490 ei_next (&ei);
491 }
492*/
493
494#define FOR_EACH_EDGE(EDGE,ITER,EDGE_VEC) \
495 for ((ITER) = ei_start ((EDGE_VEC)); \
496 ei_cond ((ITER), &(EDGE)); \
497 ei_next (&(ITER)))
498
499#define CLEANUP_EXPENSIVE 1 /* Do relatively expensive optimizations
500 except for edge forwarding */
501#define CLEANUP_CROSSJUMP 2 /* Do crossjumping. */
502#define CLEANUP_POST_REGSTACK 4 /* We run after reg-stack and need
503 to care REG_DEAD notes. */
504#define CLEANUP_THREADING 8 /* Do jump threading. */
505#define CLEANUP_NO_INSN_DEL 16 /* Do not try to delete trivially dead
506 insns. */
507#define CLEANUP_CFGLAYOUT 32 /* Do cleanup in cfglayout mode. */
508#define CLEANUP_CFG_CHANGED 64 /* The caller changed the CFG. */
509
510/* Return true if BB is in a transaction. */
511
512static inline bool
513bb_in_transaction (basic_block bb)
514{
515 return bb->flags & BB_IN_TRANSACTION;
516}
517
518/* Return true when one of the predecessor edges of BB is marked with EDGE_EH. */
519static inline bool
520bb_has_eh_pred (basic_block bb)
521{
522 edge e;
523 edge_iterator ei;
524
525 FOR_EACH_EDGE (e, ei, bb->preds)
526 {
527 if (e->flags & EDGE_EH)
528 return true;
529 }
530 return false;
531}
532
533/* Return true when one of the predecessor edges of BB is marked with EDGE_ABNORMAL. */
534static inline bool
535bb_has_abnormal_pred (basic_block bb)
536{
537 edge e;
538 edge_iterator ei;
539
540 FOR_EACH_EDGE (e, ei, bb->preds)
541 {
542 if (e->flags & EDGE_ABNORMAL)
543 return true;
544 }
545 return false;
546}
547
548/* Return the fallthru edge in EDGES if it exists, NULL otherwise. */
549static inline edge
550find_fallthru_edge (vec<edge, va_gc> *edges)
551{
552 edge e;
553 edge_iterator ei;
554
555 FOR_EACH_EDGE (e, ei, edges)
556 if (e->flags & EDGE_FALLTHRU)
557 break;
558
559 return e;
560}
561
562/* Check tha probability is sane. */
563
564static inline void
565check_probability (int prob)
566{
567 gcc_checking_assert (prob >= 0 && prob <= REG_BR_PROB_BASE);
568}
569
570/* Given PROB1 and PROB2, return PROB1*PROB2/REG_BR_PROB_BASE.
571 Used to combine BB probabilities. */
572
573static inline int
574combine_probabilities (int prob1, int prob2)
575{
576 check_probability (prob1);
577 check_probability (prob2);
578 return RDIV (prob1 * prob2, REG_BR_PROB_BASE);
579}
580
581/* Apply scale factor SCALE on frequency or count FREQ. Use this
582 interface when potentially scaling up, so that SCALE is not
583 constrained to be < REG_BR_PROB_BASE. */
584
585static inline gcov_type
586apply_scale (gcov_type freq, gcov_type scale)
587{
588 return RDIV (freq * scale, REG_BR_PROB_BASE);
589}
590
591/* Apply probability PROB on frequency or count FREQ. */
592
593static inline gcov_type
594apply_probability (gcov_type freq, int prob)
595{
596 check_probability (prob);
597 return apply_scale (freq, prob);
598}
599
600/* Return inverse probability for PROB. */
601
602static inline int
603inverse_probability (int prob1)
604{
605 check_probability (prob1);
606 return REG_BR_PROB_BASE - prob1;
607}
608
609/* Return true if BB has at least one abnormal outgoing edge. */
610
611static inline bool
612has_abnormal_or_eh_outgoing_edge_p (basic_block bb)
613{
614 edge e;
615 edge_iterator ei;
616
617 FOR_EACH_EDGE (e, ei, bb->succs)
618 if (e->flags & (EDGE_ABNORMAL | EDGE_EH))
619 return true;
620
621 return false;
622}
623
624/* Return true when one of the predecessor edges of BB is marked with
625 EDGE_ABNORMAL_CALL or EDGE_EH. */
626
627static inline bool
628has_abnormal_call_or_eh_pred_edge_p (basic_block bb)
629{
630 edge e;
631 edge_iterator ei;
632
633 FOR_EACH_EDGE (e, ei, bb->preds)
634 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
635 return true;
636
637 return false;
638}
639
640/* Return count of edge E. */
641inline profile_count edge_def::count () const
642{
643 return src->count.apply_probability (probability);
644}
645
646#endif /* GCC_BASIC_BLOCK_H */
647