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1 : : /* Control flow graph building code for GNU compiler.
2 : : Copyright (C) 1987-2024 Free Software Foundation, Inc.
3 : :
4 : : This file is part of GCC.
5 : :
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
9 : : version.
10 : :
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
14 : : for more details.
15 : :
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/>. */
19 : :
20 : :
21 : : #include "config.h"
22 : : #include "system.h"
23 : : #include "coretypes.h"
24 : : #include "backend.h"
25 : : #include "rtl.h"
26 : : #include "cfghooks.h"
27 : : #include "memmodel.h"
28 : : #include "emit-rtl.h"
29 : : #include "cfgrtl.h"
30 : : #include "cfganal.h"
31 : : #include "cfgbuild.h"
32 : : #include "except.h"
33 : : #include "stmt.h"
34 : :
35 : : static void make_edges (basic_block, basic_block, int);
36 : : static void make_label_edge (sbitmap, basic_block, rtx, int);
37 : : static void find_bb_boundaries (basic_block);
38 : : static void compute_outgoing_frequencies (basic_block);
39 : :
40 : : /* Return true if insn is something that should be contained inside basic
41 : : block. */
42 : :
43 : : bool
44 : 176473974 : inside_basic_block_p (const rtx_insn *insn)
45 : : {
46 : 176473974 : switch (GET_CODE (insn))
47 : : {
48 : 10644629 : case CODE_LABEL:
49 : : /* Avoid creating of basic block for jumptables. */
50 : 10644629 : return (NEXT_INSN (insn) == 0
51 : 10644629 : || ! JUMP_TABLE_DATA_P (NEXT_INSN (insn)));
52 : :
53 : : case JUMP_INSN:
54 : : case CALL_INSN:
55 : : case INSN:
56 : : case DEBUG_INSN:
57 : : return true;
58 : :
59 : : case JUMP_TABLE_DATA:
60 : : case BARRIER:
61 : : case NOTE:
62 : : return false;
63 : :
64 : 0 : default:
65 : 0 : gcc_unreachable ();
66 : : }
67 : : }
68 : :
69 : : /* Return true if INSN may cause control flow transfer, so it should be last in
70 : : the basic block. */
71 : :
72 : : bool
73 : 9316433793 : control_flow_insn_p (const rtx_insn *insn)
74 : : {
75 : 9316433793 : switch (GET_CODE (insn))
76 : : {
77 : : case NOTE:
78 : : case CODE_LABEL:
79 : : case DEBUG_INSN:
80 : : return false;
81 : :
82 : : case JUMP_INSN:
83 : : return true;
84 : :
85 : 376619211 : case CALL_INSN:
86 : : /* Noreturn and sibling call instructions terminate the basic blocks
87 : : (but only if they happen unconditionally). */
88 : 376619211 : if ((SIBLING_CALL_P (insn)
89 : 375636217 : || find_reg_note (insn, REG_NORETURN, 0))
90 : 379939558 : && GET_CODE (PATTERN (insn)) != COND_EXEC)
91 : : return true;
92 : :
93 : : /* Call insn may return to the nonlocal goto handler. */
94 : 372315870 : if (can_nonlocal_goto (insn))
95 : : return true;
96 : : break;
97 : :
98 : 4845548094 : case INSN:
99 : : /* Treat trap instructions like noreturn calls (same provision). */
100 : 4845548094 : if (GET_CODE (PATTERN (insn)) == TRAP_IF
101 : 4845548094 : && XEXP (PATTERN (insn), 0) == const1_rtx)
102 : : return true;
103 : 4845473432 : if (!cfun->can_throw_non_call_exceptions)
104 : : return false;
105 : : break;
106 : :
107 : : case JUMP_TABLE_DATA:
108 : : case BARRIER:
109 : : /* It is nonsense to reach this when looking for the
110 : : end of basic block, but before dead code is eliminated
111 : : this may happen. */
112 : : return false;
113 : :
114 : 0 : default:
115 : 0 : gcc_unreachable ();
116 : : }
117 : :
118 : 1681806021 : return can_throw_internal (insn);
119 : : }
120 : :
121 : :
122 : : /* Create an edge between two basic blocks. FLAGS are auxiliary information
123 : : about the edge that is accumulated between calls. */
124 : :
125 : : /* Create an edge from a basic block to a label. */
126 : :
127 : : static void
128 : 15193946 : make_label_edge (sbitmap edge_cache, basic_block src, rtx label, int flags)
129 : : {
130 : 15193946 : gcc_assert (LABEL_P (label));
131 : :
132 : : /* If the label was never emitted, this insn is junk, but avoid a
133 : : crash trying to refer to BLOCK_FOR_INSN (label). This can happen
134 : : as a result of a syntax error and a diagnostic has already been
135 : : printed. */
136 : :
137 : 15193946 : if (INSN_UID (label) == 0)
138 : : return;
139 : :
140 : 15193946 : cached_make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
141 : : }
142 : :
143 : : /* Create the edges generated by INSN in REGION. */
144 : :
145 : : void
146 : 9717448 : rtl_make_eh_edge (sbitmap edge_cache, basic_block src, rtx insn)
147 : : {
148 : 9717448 : eh_landing_pad lp = get_eh_landing_pad_from_rtx (insn);
149 : :
150 : 9717448 : if (lp)
151 : : {
152 : 1231684 : rtx_insn *label = lp->landing_pad;
153 : :
154 : : /* During initial rtl generation, use the post_landing_pad. */
155 : 1231684 : if (label == NULL)
156 : : {
157 : 689814 : gcc_assert (lp->post_landing_pad);
158 : 689814 : label = label_rtx (lp->post_landing_pad);
159 : : }
160 : :
161 : 1231684 : make_label_edge (edge_cache, src, label,
162 : : EDGE_ABNORMAL | EDGE_EH
163 : 1231684 : | (CALL_P (insn) ? EDGE_ABNORMAL_CALL : 0));
164 : : }
165 : 9717448 : }
166 : :
167 : : /* States of basic block as seen by find_many_sub_basic_blocks. */
168 : : enum state {
169 : : /* Basic blocks created via split_block belong to this state.
170 : : make_edges will examine these basic blocks to see if we need to
171 : : create edges going out of them. */
172 : : BLOCK_NEW = 0,
173 : :
174 : : /* Basic blocks that do not need examining belong to this state.
175 : : These blocks will be left intact. In particular, make_edges will
176 : : not create edges going out of these basic blocks. */
177 : : BLOCK_ORIGINAL,
178 : :
179 : : /* Basic blocks that may need splitting (due to a label appearing in
180 : : the middle, etc) belong to this state. After splitting them,
181 : : make_edges will create edges going out of them as needed. */
182 : : BLOCK_TO_SPLIT
183 : : };
184 : :
185 : : #define STATE(BB) (enum state) ((size_t) (BB)->aux)
186 : : #define SET_STATE(BB, STATE) ((BB)->aux = (void *) (size_t) (STATE))
187 : :
188 : : /* Used internally by purge_dead_tablejump_edges, ORed into state. */
189 : : #define BLOCK_USED_BY_TABLEJUMP 32
190 : : #define FULL_STATE(BB) ((size_t) (BB)->aux)
191 : :
192 : : /* Identify the edges going out of basic blocks between MIN and MAX,
193 : : inclusive, that have their states set to BLOCK_NEW or
194 : : BLOCK_TO_SPLIT.
195 : :
196 : : UPDATE_P should be nonzero if we are updating CFG and zero if we
197 : : are building CFG from scratch. */
198 : :
199 : : static void
200 : 3770028 : make_edges (basic_block min, basic_block max, int update_p)
201 : : {
202 : 3770028 : basic_block bb;
203 : 3770028 : sbitmap edge_cache = NULL;
204 : :
205 : : /* Heavy use of computed goto in machine-generated code can lead to
206 : : nearly fully-connected CFGs. In that case we spend a significant
207 : : amount of time searching the edge lists for duplicates. */
208 : 3770028 : if (!vec_safe_is_empty (forced_labels)
209 : 3725603 : || cfun->cfg->max_jumptable_ents > 100)
210 : 44529 : edge_cache = sbitmap_alloc (last_basic_block_for_fn (cfun));
211 : :
212 : : /* By nature of the way these get numbered, ENTRY_BLOCK_PTR->next_bb block
213 : : is always the entry. */
214 : 3770028 : if (min == ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb)
215 : 3317664 : make_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun), min, EDGE_FALLTHRU);
216 : :
217 : 37457899 : FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb)
218 : : {
219 : 33687871 : rtx_insn *insn;
220 : 33687871 : enum rtx_code code;
221 : 33687871 : edge e;
222 : 33687871 : edge_iterator ei;
223 : :
224 : 33687871 : if (STATE (bb) == BLOCK_ORIGINAL)
225 : 8445555 : continue;
226 : :
227 : : /* If we have an edge cache, cache edges going out of BB. */
228 : 25242316 : if (edge_cache)
229 : : {
230 : 193124 : bitmap_clear (edge_cache);
231 : 193124 : if (update_p)
232 : : {
233 : 432435 : FOR_EACH_EDGE (e, ei, bb->succs)
234 : 239311 : if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun))
235 : 217097 : bitmap_set_bit (edge_cache, e->dest->index);
236 : : }
237 : : }
238 : :
239 : 25242316 : if (LABEL_P (BB_HEAD (bb))
240 : 25242316 : && LABEL_ALT_ENTRY_P (BB_HEAD (bb)))
241 : 0 : cached_make_edge (NULL, ENTRY_BLOCK_PTR_FOR_FN (cfun), bb, 0);
242 : :
243 : : /* Examine the last instruction of the block, and discover the
244 : : ways we can leave the block. */
245 : :
246 : 25242316 : insn = BB_END (bb);
247 : 25242316 : code = GET_CODE (insn);
248 : :
249 : : /* A branch. */
250 : 25242316 : if (code == JUMP_INSN)
251 : : {
252 : 14254799 : rtx tmp;
253 : 14254799 : rtx_jump_table_data *table;
254 : :
255 : : /* Recognize a non-local goto as a branch outside the
256 : : current function. */
257 : 14254799 : if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
258 : : ;
259 : :
260 : : /* Recognize a tablejump and do the right thing. */
261 : 14253371 : else if (tablejump_p (insn, NULL, &table))
262 : : {
263 : 8174 : rtvec vec = table->get_labels ();
264 : 8174 : int j;
265 : :
266 : 210881 : for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
267 : 202707 : make_label_edge (edge_cache, bb,
268 : 202707 : XEXP (RTVEC_ELT (vec, j), 0), 0);
269 : :
270 : : /* Some targets (eg, ARM) emit a conditional jump that also
271 : : contains the out-of-range target. Scan for these and
272 : : add an edge if necessary. */
273 : 8174 : if ((tmp = single_set (insn)) != NULL
274 : 8174 : && SET_DEST (tmp) == pc_rtx
275 : 8174 : && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
276 : 8174 : && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
277 : 0 : make_label_edge (edge_cache, bb,
278 : 0 : label_ref_label (XEXP (SET_SRC (tmp), 2)), 0);
279 : : }
280 : :
281 : : /* If this is a computed jump, then mark it as reaching
282 : : everything on the forced_labels list. */
283 : 14245197 : else if (computed_jump_p (insn))
284 : : {
285 : : rtx_insn *insn;
286 : : unsigned int i;
287 : 14256499 : FOR_EACH_VEC_SAFE_ELT (forced_labels, i, insn)
288 : 1307 : make_label_edge (edge_cache, bb, insn, EDGE_ABNORMAL);
289 : : }
290 : :
291 : : /* Returns create an exit out. */
292 : 14244746 : else if (returnjump_p (insn))
293 : 555167 : cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun), 0);
294 : :
295 : : /* Recognize asm goto and do the right thing. */
296 : 13689579 : else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL)
297 : : {
298 : 562 : int i, n = ASM_OPERANDS_LABEL_LENGTH (tmp);
299 : 1467 : for (i = 0; i < n; ++i)
300 : 905 : make_label_edge (edge_cache, bb,
301 : 905 : XEXP (ASM_OPERANDS_LABEL (tmp, i), 0), 0);
302 : : }
303 : :
304 : : /* Otherwise, we have a plain conditional or unconditional jump. */
305 : : else
306 : : {
307 : 13689017 : gcc_assert (JUMP_LABEL (insn));
308 : 13689017 : make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
309 : : }
310 : : }
311 : :
312 : : /* If this is a sibling call insn, then this is in effect a combined call
313 : : and return, and so we need an edge to the exit block. No need to
314 : : worry about EH edges, since we wouldn't have created the sibling call
315 : : in the first place. */
316 : 25242316 : if (code == CALL_INSN && SIBLING_CALL_P (insn))
317 : 142583 : cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun),
318 : : EDGE_SIBCALL | EDGE_ABNORMAL);
319 : :
320 : : /* If this is a CALL_INSN, then mark it as reaching the active EH
321 : : handler for this CALL_INSN. If we're handling non-call
322 : : exceptions then any insn can reach any of the active handlers.
323 : : Also mark the CALL_INSN as reaching any nonlocal goto handler. */
324 : 25099733 : else if (code == CALL_INSN || cfun->can_throw_non_call_exceptions)
325 : : {
326 : : /* Add any appropriate EH edges. */
327 : 9706992 : rtl_make_eh_edge (edge_cache, bb, insn);
328 : :
329 : 9706992 : if (code == CALL_INSN)
330 : : {
331 : 2398615 : if (can_nonlocal_goto (insn))
332 : : {
333 : : /* ??? This could be made smarter: in some cases it's
334 : : possible to tell that certain calls will not do a
335 : : nonlocal goto. For example, if the nested functions
336 : : that do the nonlocal gotos do not have their addresses
337 : : taken, then only calls to those functions or to other
338 : : nested functions that use them could possibly do
339 : : nonlocal gotos. */
340 : 72749 : for (rtx_insn_list *x = nonlocal_goto_handler_labels;
341 : 72749 : x;
342 : 68326 : x = x->next ())
343 : 68326 : make_label_edge (edge_cache, bb, x->insn (),
344 : : EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
345 : : }
346 : :
347 : 2398615 : if (flag_tm)
348 : : {
349 : 1499 : rtx note;
350 : 3567 : for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
351 : 2068 : if (REG_NOTE_KIND (note) == REG_TM)
352 : 0 : make_label_edge (edge_cache, bb, XEXP (note, 0),
353 : : EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
354 : : }
355 : : }
356 : : }
357 : :
358 : : /* Find out if we can drop through to the next block. */
359 : 25242316 : insn = NEXT_INSN (insn);
360 : 25242316 : e = find_edge (bb, EXIT_BLOCK_PTR_FOR_FN (cfun));
361 : 25242316 : if (e && e->flags & EDGE_FALLTHRU)
362 : 25242316 : insn = NULL;
363 : :
364 : : while (insn
365 : 23429920 : && NOTE_P (insn)
366 : 36804043 : && NOTE_KIND (insn) != NOTE_INSN_BASIC_BLOCK)
367 : 2759 : insn = NEXT_INSN (insn);
368 : :
369 : 25242316 : if (!insn)
370 : 1815155 : cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun),
371 : : EDGE_FALLTHRU);
372 : 23427161 : else if (bb->next_bb != EXIT_BLOCK_PTR_FOR_FN (cfun))
373 : : {
374 : 22832908 : if (insn == BB_HEAD (bb->next_bb))
375 : 17336114 : cached_make_edge (edge_cache, bb, bb->next_bb, EDGE_FALLTHRU);
376 : : }
377 : : }
378 : :
379 : 3770028 : if (edge_cache)
380 : 44529 : sbitmap_free (edge_cache);
381 : 3770028 : }
382 : :
383 : : static void
384 : 151098 : mark_tablejump_edge (rtx label)
385 : : {
386 : 151098 : basic_block bb;
387 : :
388 : 151098 : gcc_assert (LABEL_P (label));
389 : : /* See comment in make_label_edge. */
390 : 151098 : if (INSN_UID (label) == 0)
391 : : return;
392 : 151098 : bb = BLOCK_FOR_INSN (label);
393 : 151098 : SET_STATE (bb, FULL_STATE (bb) | BLOCK_USED_BY_TABLEJUMP);
394 : : }
395 : :
396 : : static void
397 : 5516 : purge_dead_tablejump_edges (basic_block bb, rtx_jump_table_data *table)
398 : : {
399 : 5516 : rtx_insn *insn = BB_END (bb);
400 : 5516 : rtx tmp;
401 : 5516 : rtvec vec;
402 : 5516 : int j;
403 : 5516 : edge_iterator ei;
404 : 5516 : edge e;
405 : :
406 : 5516 : vec = table->get_labels ();
407 : :
408 : 156614 : for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
409 : 151098 : mark_tablejump_edge (XEXP (RTVEC_ELT (vec, j), 0));
410 : :
411 : : /* Some targets (eg, ARM) emit a conditional jump that also
412 : : contains the out-of-range target. Scan for these and
413 : : add an edge if necessary. */
414 : 5516 : if ((tmp = single_set (insn)) != NULL
415 : 5516 : && SET_DEST (tmp) == pc_rtx
416 : 5516 : && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
417 : 5516 : && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
418 : 0 : mark_tablejump_edge (label_ref_label (XEXP (SET_SRC (tmp), 2)));
419 : :
420 : 68780 : for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
421 : : {
422 : 63264 : if (FULL_STATE (e->dest) & BLOCK_USED_BY_TABLEJUMP)
423 : 61742 : SET_STATE (e->dest, FULL_STATE (e->dest)
424 : : & ~(size_t) BLOCK_USED_BY_TABLEJUMP);
425 : 1522 : else if (!(e->flags & (EDGE_ABNORMAL | EDGE_EH)))
426 : : {
427 : 1522 : remove_edge (e);
428 : 1522 : continue;
429 : : }
430 : 61742 : ei_next (&ei);
431 : : }
432 : 5516 : }
433 : :
434 : : /* Scan basic block BB for possible BB boundaries inside the block
435 : : and create new basic blocks in the progress. */
436 : :
437 : : static void
438 : 25563712 : find_bb_boundaries (basic_block bb)
439 : : {
440 : 25563712 : basic_block orig_bb = bb;
441 : 25563712 : rtx_insn *insn = BB_HEAD (bb);
442 : 25563712 : rtx_insn *end = BB_END (bb), *x;
443 : 25563712 : rtx_jump_table_data *table;
444 : 25563712 : rtx_insn *flow_transfer_insn = NULL;
445 : 25563712 : rtx_insn *debug_insn = NULL;
446 : 25563712 : edge fallthru = NULL;
447 : 25563712 : bool skip_purge;
448 : 25563712 : bool seen_note_after_debug = false;
449 : :
450 : 25563712 : if (insn == end)
451 : 168691 : return;
452 : :
453 : 25405654 : if (DEBUG_INSN_P (insn) || DEBUG_INSN_P (end))
454 : : {
455 : : /* Check whether, without debug insns, the insn==end test above
456 : : would have caused us to return immediately, and behave the
457 : : same way even with debug insns. If we don't do this, debug
458 : : insns could cause us to purge dead edges at different times,
459 : : which could in turn change the cfg and affect codegen
460 : : decisions in subtle but undesirable ways. */
461 : 353902 : while (insn != end && DEBUG_INSN_P (insn))
462 : 0 : insn = NEXT_INSN (insn);
463 : : rtx_insn *e = end;
464 : 2612344 : while (insn != e && DEBUG_INSN_P (e))
465 : 2258442 : e = PREV_INSN (e);
466 : 353902 : if (insn == e)
467 : : {
468 : : /* If there are debug insns after a single insn that is a
469 : : control flow insn in the block, we'd have left right
470 : : away, but we should clean up the debug insns after the
471 : : control flow insn, because they can't remain in the same
472 : : block. So, do the debug insn cleaning up, but then bail
473 : : out without purging dead edges as we would if the debug
474 : : insns hadn't been there. */
475 : 10633 : if (e != end && !DEBUG_INSN_P (e) && control_flow_insn_p (e))
476 : : {
477 : 0 : skip_purge = true;
478 : 0 : flow_transfer_insn = e;
479 : 0 : goto clean_up_debug_after_control_flow;
480 : : }
481 : 10633 : return;
482 : : }
483 : : }
484 : :
485 : 25395021 : if (LABEL_P (insn))
486 : 11996029 : insn = NEXT_INSN (insn);
487 : :
488 : : /* Scan insn chain and try to find new basic block boundaries. */
489 : 286527647 : while (1)
490 : : {
491 : 311922668 : enum rtx_code code = GET_CODE (insn);
492 : :
493 : 311922668 : if (code == DEBUG_INSN)
494 : : {
495 : 67724294 : if (flow_transfer_insn && !debug_insn)
496 : : {
497 : 491 : debug_insn = insn;
498 : 491 : seen_note_after_debug = false;
499 : : }
500 : : }
501 : : /* In case we've previously seen an insn that effects a control
502 : : flow transfer, split the block. */
503 : 244198374 : else if ((flow_transfer_insn || code == CODE_LABEL)
504 : 244198374 : && inside_basic_block_p (insn))
505 : : {
506 : 2327576 : rtx_insn *prev = PREV_INSN (insn);
507 : :
508 : : /* If the first non-debug inside_basic_block_p insn after a control
509 : : flow transfer is not a label, split the block before the debug
510 : : insn instead of before the non-debug insn, so that the debug
511 : : insns are not lost. */
512 : 2327576 : if (debug_insn && code != CODE_LABEL && code != BARRIER)
513 : : {
514 : 491 : prev = PREV_INSN (debug_insn);
515 : 491 : if (seen_note_after_debug)
516 : : {
517 : : /* Though, if there are NOTEs intermixed with DEBUG_INSNs,
518 : : move the NOTEs before the DEBUG_INSNs and split after
519 : : the last NOTE. */
520 : : rtx_insn *first = NULL, *last = NULL;
521 : 0 : for (x = debug_insn; x != insn; x = NEXT_INSN (x))
522 : : {
523 : 0 : if (NOTE_P (x))
524 : : {
525 : 0 : if (first == NULL)
526 : 0 : first = x;
527 : : last = x;
528 : : }
529 : : else
530 : : {
531 : 0 : gcc_assert (DEBUG_INSN_P (x));
532 : 0 : if (first)
533 : : {
534 : 0 : reorder_insns_nobb (first, last, prev);
535 : 0 : prev = last;
536 : 0 : first = last = NULL;
537 : : }
538 : : }
539 : : }
540 : 0 : if (first)
541 : : {
542 : 0 : reorder_insns_nobb (first, last, prev);
543 : 0 : prev = last;
544 : : }
545 : : }
546 : : }
547 : 2327576 : fallthru = split_block (bb, prev);
548 : 2327576 : if (flow_transfer_insn)
549 : : {
550 : 1819247 : BB_END (bb) = flow_transfer_insn;
551 : :
552 : 1819247 : rtx_insn *next;
553 : : /* Clean up the bb field for the insns between the blocks. */
554 : 1819247 : for (x = NEXT_INSN (flow_transfer_insn);
555 : 2173754 : x != BB_HEAD (fallthru->dest);
556 : : x = next)
557 : : {
558 : 354507 : next = NEXT_INSN (x);
559 : : /* Debug insns should not be in between basic blocks,
560 : : drop them on the floor. */
561 : 354507 : if (DEBUG_INSN_P (x))
562 : 0 : delete_insn (x);
563 : 354507 : else if (!BARRIER_P (x))
564 : 0 : set_block_for_insn (x, NULL);
565 : : }
566 : : }
567 : :
568 : 2327576 : bb = fallthru->dest;
569 : 2327576 : remove_edge (fallthru);
570 : : /* BB is unreachable at this point - we need to determine its profile
571 : : once edges are built. */
572 : 2327576 : bb->count = profile_count::uninitialized ();
573 : 2327576 : flow_transfer_insn = NULL;
574 : 2327576 : debug_insn = NULL;
575 : 2327576 : if (code == CODE_LABEL && LABEL_ALT_ENTRY_P (insn))
576 : 0 : make_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun), bb, 0);
577 : : }
578 : 241870798 : else if (code == BARRIER)
579 : : {
580 : : /* __builtin_unreachable () may cause a barrier to be emitted in
581 : : the middle of a BB. We need to split it in the same manner as
582 : : if the barrier were preceded by a control_flow_insn_p insn. */
583 : 470715 : if (!flow_transfer_insn)
584 : 43 : flow_transfer_insn = prev_nonnote_nondebug_insn_bb (insn);
585 : : debug_insn = NULL;
586 : : }
587 : 241400083 : else if (debug_insn)
588 : : {
589 : 0 : if (code == NOTE)
590 : : seen_note_after_debug = true;
591 : : else
592 : : /* Jump tables. */
593 : 241400083 : debug_insn = NULL;
594 : : }
595 : :
596 : 311922668 : if (control_flow_insn_p (insn))
597 : 19181692 : flow_transfer_insn = insn;
598 : 311922668 : if (insn == end)
599 : : break;
600 : 286527647 : insn = NEXT_INSN (insn);
601 : 286527647 : }
602 : :
603 : : /* In case expander replaced normal insn by sequence terminating by
604 : : return and barrier, or possibly other sequence not behaving like
605 : : ordinary jump, we need to take care and move basic block boundary. */
606 : 25395021 : if (flow_transfer_insn && flow_transfer_insn != end)
607 : : {
608 : : skip_purge = false;
609 : :
610 : 116208 : clean_up_debug_after_control_flow:
611 : 116208 : BB_END (bb) = flow_transfer_insn;
612 : :
613 : : /* Clean up the bb field for the insns that do not belong to BB. */
614 : 116208 : rtx_insn *next;
615 : 116208 : for (x = NEXT_INSN (flow_transfer_insn); ; x = next)
616 : : {
617 : 116208 : next = NEXT_INSN (x);
618 : : /* Debug insns should not be in between basic blocks,
619 : : drop them on the floor. */
620 : 116208 : if (DEBUG_INSN_P (x))
621 : 0 : delete_insn (x);
622 : 116208 : else if (!BARRIER_P (x))
623 : 0 : set_block_for_insn (x, NULL);
624 : 116208 : if (x == end)
625 : : break;
626 : : }
627 : :
628 : 116208 : if (skip_purge)
629 : : return;
630 : : }
631 : :
632 : : /* We've possibly replaced the conditional jump by conditional jump
633 : : followed by cleanup at fallthru edge, so the outgoing edges may
634 : : be dead. */
635 : 25395021 : purge_dead_edges (bb);
636 : :
637 : : /* purge_dead_edges doesn't handle tablejump's, but if we have split the
638 : : basic block, we might need to kill some edges. */
639 : 25395021 : if (bb != orig_bb && tablejump_p (BB_END (bb), NULL, &table))
640 : 5516 : purge_dead_tablejump_edges (bb, table);
641 : : }
642 : :
643 : : /* Assume that frequency of basic block B is known. Compute frequencies
644 : : and probabilities of outgoing edges. */
645 : :
646 : : static void
647 : 2888244 : compute_outgoing_frequencies (basic_block b)
648 : : {
649 : 2888244 : edge e, f;
650 : 2888244 : edge_iterator ei;
651 : :
652 : 2888244 : if (EDGE_COUNT (b->succs) == 2)
653 : : {
654 : 1568310 : rtx note = find_reg_note (BB_END (b), REG_BR_PROB, NULL);
655 : 1568310 : int probability;
656 : :
657 : 1568310 : if (note)
658 : : {
659 : 1071957 : probability = XINT (note, 0);
660 : 1071957 : e = BRANCH_EDGE (b);
661 : 1071957 : e->probability
662 : 1071957 : = profile_probability::from_reg_br_prob_note (probability);
663 : 1071957 : f = FALLTHRU_EDGE (b);
664 : 1071957 : f->probability = e->probability.invert ();
665 : 2382705 : return;
666 : : }
667 : : else
668 : : {
669 : 496353 : guess_outgoing_edge_probabilities (b);
670 : : }
671 : : }
672 : 1319934 : else if (single_succ_p (b))
673 : : {
674 : 1310748 : e = single_succ_edge (b);
675 : 1310748 : e->probability = profile_probability::always ();
676 : 1310748 : return;
677 : : }
678 : : else
679 : : {
680 : : /* We rely on BBs with more than two successors to have sane probabilities
681 : : and do not guess them here. For BBs terminated by switch statements
682 : : expanded to jump-table jump, we have done the right thing during
683 : : expansion. For EH edges, we still guess the probabilities here. */
684 : 9186 : bool complex_edge = false;
685 : 71200 : FOR_EACH_EDGE (e, ei, b->succs)
686 : 63111 : if (e->flags & EDGE_COMPLEX)
687 : : {
688 : : complex_edge = true;
689 : : break;
690 : : }
691 : 9186 : if (complex_edge)
692 : 1097 : guess_outgoing_edge_probabilities (b);
693 : : }
694 : : }
695 : :
696 : : /* Update the profile information for BB, which was created by splitting
697 : : an RTL block that had a non-final jump. */
698 : :
699 : : static void
700 : 1944237 : update_profile_for_new_sub_basic_block (basic_block bb)
701 : : {
702 : 1944237 : edge e;
703 : 1944237 : edge_iterator ei;
704 : :
705 : 1944237 : bool initialized_src = false, uninitialized_src = false;
706 : 1944237 : bb->count = profile_count::zero ();
707 : 4444758 : FOR_EACH_EDGE (e, ei, bb->preds)
708 : : {
709 : 2500521 : if (e->count ().initialized_p ())
710 : : {
711 : 2480710 : bb->count += e->count ();
712 : 2480710 : initialized_src = true;
713 : : }
714 : : else
715 : : uninitialized_src = true;
716 : : }
717 : : /* When some edges are missing with read profile, this is
718 : : most likely because RTL expansion introduced loop.
719 : : When profile is guessed we may have BB that is reachable
720 : : from unlikely path as well as from normal path.
721 : :
722 : : TODO: We should handle loops created during BB expansion
723 : : correctly here. For now we assume all those loop to cycle
724 : : precisely once. */
725 : 1944237 : if (!initialized_src
726 : 1939869 : || (uninitialized_src
727 : 15692 : && profile_status_for_fn (cfun) < PROFILE_GUESSED))
728 : 4368 : bb->count = profile_count::uninitialized ();
729 : :
730 : 1944237 : compute_outgoing_frequencies (bb);
731 : 1944237 : }
732 : :
733 : : /* Assume that some pass has inserted labels or control flow
734 : : instructions within a basic block. Split basic blocks as needed
735 : : and create edges. */
736 : :
737 : : void
738 : 3510229 : find_many_sub_basic_blocks (sbitmap blocks)
739 : : {
740 : 3510229 : basic_block bb, min, max;
741 : 3510229 : bool found = false;
742 : 3510229 : auto_vec<unsigned int> n_succs;
743 : 3510229 : n_succs.safe_grow_cleared (last_basic_block_for_fn (cfun), true);
744 : :
745 : 55232250 : FOR_EACH_BB_FN (bb, cfun)
746 : 80789101 : SET_STATE (bb,
747 : : bitmap_bit_p (blocks, bb->index) ? BLOCK_TO_SPLIT : BLOCK_ORIGINAL);
748 : :
749 : 57040216 : FOR_EACH_BB_FN (bb, cfun)
750 : 53529987 : if (STATE (bb) == BLOCK_TO_SPLIT)
751 : : {
752 : 22654941 : int n = last_basic_block_for_fn (cfun);
753 : 22654941 : unsigned int ns = EDGE_COUNT (bb->succs);
754 : :
755 : 22654941 : find_bb_boundaries (bb);
756 : 44305769 : if (n == last_basic_block_for_fn (cfun) && ns == EDGE_COUNT (bb->succs))
757 : 21834245 : n_succs[bb->index] = EDGE_COUNT (bb->succs);
758 : : }
759 : :
760 : 7802156 : FOR_EACH_BB_FN (bb, cfun)
761 : 7802156 : if (STATE (bb) != BLOCK_ORIGINAL)
762 : : {
763 : : found = true;
764 : : break;
765 : : }
766 : :
767 : 3510229 : if (!found)
768 : 0 : return;
769 : :
770 : : min = max = bb;
771 : 52748289 : for (; bb != EXIT_BLOCK_PTR_FOR_FN (cfun); bb = bb->next_bb)
772 : 49238060 : if (STATE (bb) != BLOCK_ORIGINAL)
773 : 24462907 : max = bb;
774 : :
775 : : /* Now re-scan and wire in all edges. This expect simple (conditional)
776 : : jumps at the end of each new basic blocks. */
777 : 3510229 : make_edges (min, max, 1);
778 : :
779 : : /* Update branch probabilities. Expect only (un)conditional jumps
780 : : to be created with only the forward edges. */
781 : 3510229 : if (profile_status_for_fn (cfun) != PROFILE_ABSENT)
782 : 28754663 : FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb)
783 : : {
784 : 26277943 : if (STATE (bb) == BLOCK_ORIGINAL)
785 : 7365707 : continue;
786 : 18912236 : if (STATE (bb) == BLOCK_NEW)
787 : : {
788 : 1455359 : update_profile_for_new_sub_basic_block (bb);
789 : 1455359 : continue;
790 : : }
791 : : /* If nothing changed, there is no need to create new BBs. */
792 : 34904351 : if (EDGE_COUNT (bb->succs) == n_succs[bb->index])
793 : : {
794 : : /* In rare occassions RTL expansion might have mistakely assigned
795 : : a probabilities different from what is in CFG. This happens
796 : : when we try to split branch to two but optimize out the
797 : : second branch during the way. See PR81030. */
798 : 9799253 : if (JUMP_P (BB_END (bb)) && any_condjump_p (BB_END (bb))
799 : 22994424 : && EDGE_COUNT (bb->succs) >= 2)
800 : 6237119 : update_br_prob_note (bb);
801 : 16757305 : continue;
802 : : }
803 : 699572 : compute_outgoing_frequencies (bb);
804 : : }
805 : :
806 : 57040216 : FOR_EACH_BB_FN (bb, cfun)
807 : 53529987 : SET_STATE (bb, 0);
808 : 3510229 : }
809 : :
810 : : /* Like find_many_sub_basic_blocks, but look only within BB. */
811 : :
812 : : void
813 : 2908771 : find_sub_basic_blocks (basic_block bb)
814 : : {
815 : 2908771 : basic_block end_bb = bb->next_bb;
816 : 2908771 : find_bb_boundaries (bb);
817 : 2908771 : if (bb->next_bb == end_bb)
818 : : return;
819 : :
820 : : /* Re-scan and wire in all edges. This expects simple (conditional)
821 : : jumps at the end of each new basic blocks. */
822 : 259799 : make_edges (bb, end_bb->prev_bb, 1);
823 : :
824 : : /* Update branch probabilities. Expect only (un)conditional jumps
825 : : to be created with only the forward edges. */
826 : 259799 : if (profile_status_for_fn (cfun) != PROFILE_ABSENT)
827 : : {
828 : 244435 : compute_outgoing_frequencies (bb);
829 : 733313 : for (bb = bb->next_bb; bb != end_bb; bb = bb->next_bb)
830 : 488878 : update_profile_for_new_sub_basic_block (bb);
831 : : }
832 : : }
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