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402209ff JH |
1 | /* Control flow optimization code for GNU compiler. |
2 | Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, | |
3 | 1999, 2000, 2001 Free Software Foundation, Inc. | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9 | Software Foundation; either version 2, or (at your option) any later | |
10 | version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING. If not, write to the Free | |
19 | Software Foundation, 59 Temple Place - Suite 330, Boston, MA | |
20 | 02111-1307, USA. */ | |
21 | ||
22 | /* This file contains optimizer of the control flow. The main entrypoint is | |
23 | cleanup_cfg. Following optimizations are performed: | |
24 | ||
25 | - Unreachable blocks removal | |
26 | - Edge forwarding (edge to the forwarder block is forwarded to it's | |
eaec9b3d | 27 | successor. Simplification of the branch instruction is performed by |
402209ff | 28 | underlying infrastructure so branch can be converted to simplejump or |
f5143c46 | 29 | eliminated). |
402209ff JH |
30 | - Cross jumping (tail merging) |
31 | - Conditional jump-around-simplejump simplification | |
32 | - Basic block merging. */ | |
33 | ||
34 | #include "config.h" | |
35 | #include "system.h" | |
36 | #include "rtl.h" | |
37 | #include "hard-reg-set.h" | |
38 | #include "basic-block.h" | |
39 | #include "timevar.h" | |
40 | #include "output.h" | |
41 | #include "insn-config.h" | |
42 | #include "flags.h" | |
43 | #include "recog.h" | |
44 | #include "toplev.h" | |
8ecba28a | 45 | #include "cselib.h" |
9f16e871 | 46 | #include "tm_p.h" |
402209ff JH |
47 | |
48 | #include "obstack.h" | |
49 | ||
79f5e6be | 50 | /* cleanup_cfg maintains following flags for each basic block. */ |
5f0d2358 RK |
51 | |
52 | enum bb_flags | |
53 | { | |
635559ab JH |
54 | /* Set if life info needs to be recomputed for given BB. */ |
55 | BB_UPDATE_LIFE = 1, | |
56 | /* Set if BB is the forwarder block to avoid too many | |
57 | forwarder_block_p calls. */ | |
58 | BB_FORWARDER_BLOCK = 2 | |
5f0d2358 | 59 | }; |
635559ab | 60 | |
5f0d2358 RK |
61 | #define BB_FLAGS(BB) (enum bb_flags) (BB)->aux |
62 | #define BB_SET_FLAG(BB, FLAG) \ | |
63 | (BB)->aux = (void *) (long) ((enum bb_flags) (BB)->aux | (FLAG)) | |
64 | #define BB_CLEAR_FLAG(BB, FLAG) \ | |
65 | (BB)->aux = (void *) (long) ((enum bb_flags) (BB)->aux & ~(FLAG)) | |
635559ab | 66 | |
5f0d2358 | 67 | #define FORWARDER_BLOCK_P(BB) (BB_FLAGS (BB) & BB_FORWARDER_BLOCK) |
635559ab | 68 | |
402209ff JH |
69 | static bool try_crossjump_to_edge PARAMS ((int, edge, edge)); |
70 | static bool try_crossjump_bb PARAMS ((int, basic_block)); | |
0dd0e980 JH |
71 | static bool outgoing_edges_match PARAMS ((int, |
72 | basic_block, basic_block)); | |
402209ff JH |
73 | static int flow_find_cross_jump PARAMS ((int, basic_block, basic_block, |
74 | rtx *, rtx *)); | |
0dd0e980 | 75 | static bool insns_match_p PARAMS ((int, rtx, rtx)); |
402209ff JH |
76 | |
77 | static bool delete_unreachable_blocks PARAMS ((void)); | |
ec10f7c7 | 78 | static bool label_is_jump_target_p PARAMS ((rtx, rtx)); |
4262e623 JH |
79 | static bool tail_recursion_label_p PARAMS ((rtx)); |
80 | static void merge_blocks_move_predecessor_nojumps PARAMS ((basic_block, | |
402209ff | 81 | basic_block)); |
4262e623 | 82 | static void merge_blocks_move_successor_nojumps PARAMS ((basic_block, |
402209ff | 83 | basic_block)); |
4262e623 | 84 | static bool merge_blocks PARAMS ((edge,basic_block,basic_block, |
402209ff JH |
85 | int)); |
86 | static bool try_optimize_cfg PARAMS ((int)); | |
87 | static bool try_simplify_condjump PARAMS ((basic_block)); | |
88 | static bool try_forward_edges PARAMS ((int, basic_block)); | |
8ecba28a JH |
89 | static edge thread_jump PARAMS ((int, edge, basic_block)); |
90 | static bool mark_effect PARAMS ((rtx, bitmap)); | |
635559ab JH |
91 | static void notice_new_block PARAMS ((basic_block)); |
92 | static void update_forwarder_flag PARAMS ((basic_block)); | |
93 | \f | |
94 | /* Set flags for newly created block. */ | |
95 | ||
96 | static void | |
97 | notice_new_block (bb) | |
98 | basic_block bb; | |
99 | { | |
100 | if (!bb) | |
101 | return; | |
5f0d2358 | 102 | |
635559ab JH |
103 | BB_SET_FLAG (bb, BB_UPDATE_LIFE); |
104 | if (forwarder_block_p (bb)) | |
105 | BB_SET_FLAG (bb, BB_FORWARDER_BLOCK); | |
106 | } | |
107 | ||
108 | /* Recompute forwarder flag after block has been modified. */ | |
109 | ||
110 | static void | |
111 | update_forwarder_flag (bb) | |
112 | basic_block bb; | |
113 | { | |
114 | if (forwarder_block_p (bb)) | |
115 | BB_SET_FLAG (bb, BB_FORWARDER_BLOCK); | |
116 | else | |
117 | BB_CLEAR_FLAG (bb, BB_FORWARDER_BLOCK); | |
118 | } | |
402209ff JH |
119 | \f |
120 | /* Simplify a conditional jump around an unconditional jump. | |
121 | Return true if something changed. */ | |
122 | ||
123 | static bool | |
124 | try_simplify_condjump (cbranch_block) | |
125 | basic_block cbranch_block; | |
126 | { | |
127 | basic_block jump_block, jump_dest_block, cbranch_dest_block; | |
128 | edge cbranch_jump_edge, cbranch_fallthru_edge; | |
129 | rtx cbranch_insn; | |
130 | ||
131 | /* Verify that there are exactly two successors. */ | |
132 | if (!cbranch_block->succ | |
133 | || !cbranch_block->succ->succ_next | |
134 | || cbranch_block->succ->succ_next->succ_next) | |
135 | return false; | |
136 | ||
137 | /* Verify that we've got a normal conditional branch at the end | |
138 | of the block. */ | |
139 | cbranch_insn = cbranch_block->end; | |
140 | if (!any_condjump_p (cbranch_insn)) | |
141 | return false; | |
142 | ||
143 | cbranch_fallthru_edge = FALLTHRU_EDGE (cbranch_block); | |
144 | cbranch_jump_edge = BRANCH_EDGE (cbranch_block); | |
145 | ||
146 | /* The next block must not have multiple predecessors, must not | |
147 | be the last block in the function, and must contain just the | |
148 | unconditional jump. */ | |
149 | jump_block = cbranch_fallthru_edge->dest; | |
150 | if (jump_block->pred->pred_next | |
151 | || jump_block->index == n_basic_blocks - 1 | |
635559ab | 152 | || !FORWARDER_BLOCK_P (jump_block)) |
402209ff JH |
153 | return false; |
154 | jump_dest_block = jump_block->succ->dest; | |
155 | ||
156 | /* The conditional branch must target the block after the | |
157 | unconditional branch. */ | |
158 | cbranch_dest_block = cbranch_jump_edge->dest; | |
159 | ||
160 | if (!can_fallthru (jump_block, cbranch_dest_block)) | |
161 | return false; | |
162 | ||
ca6c03ca JH |
163 | /* Invert the conditional branch. */ |
164 | if (!invert_jump (cbranch_insn, block_label (jump_dest_block), 0)) | |
165 | return false; | |
402209ff JH |
166 | |
167 | if (rtl_dump_file) | |
168 | fprintf (rtl_dump_file, "Simplifying condjump %i around jump %i\n", | |
169 | INSN_UID (cbranch_insn), INSN_UID (jump_block->end)); | |
170 | ||
171 | /* Success. Update the CFG to match. Note that after this point | |
172 | the edge variable names appear backwards; the redirection is done | |
173 | this way to preserve edge profile data. */ | |
174 | cbranch_jump_edge = redirect_edge_succ_nodup (cbranch_jump_edge, | |
175 | cbranch_dest_block); | |
176 | cbranch_fallthru_edge = redirect_edge_succ_nodup (cbranch_fallthru_edge, | |
177 | jump_dest_block); | |
178 | cbranch_jump_edge->flags |= EDGE_FALLTHRU; | |
179 | cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU; | |
180 | ||
181 | /* Delete the block with the unconditional jump, and clean up the mess. */ | |
182 | flow_delete_block (jump_block); | |
183 | tidy_fallthru_edge (cbranch_jump_edge, cbranch_block, cbranch_dest_block); | |
184 | ||
185 | return true; | |
186 | } | |
187 | \f | |
8ecba28a JH |
188 | /* Attempt to prove that operation is NOOP using CSElib or mark the effect |
189 | on register. Used by jump threading. */ | |
5f0d2358 | 190 | |
8ecba28a JH |
191 | static bool |
192 | mark_effect (exp, nonequal) | |
193 | rtx exp; | |
194 | regset nonequal; | |
195 | { | |
9f16e871 JH |
196 | int regno; |
197 | rtx dest; | |
8ecba28a JH |
198 | switch (GET_CODE (exp)) |
199 | { | |
200 | /* In case we do clobber the register, mark it as equal, as we know the | |
201 | value is dead so it don't have to match. */ | |
202 | case CLOBBER: | |
203 | if (REG_P (XEXP (exp, 0))) | |
9f16e871 JH |
204 | { |
205 | dest = XEXP (exp, 0); | |
206 | regno = REGNO (dest); | |
207 | CLEAR_REGNO_REG_SET (nonequal, regno); | |
208 | if (regno < FIRST_PSEUDO_REGISTER) | |
209 | { | |
210 | int n = HARD_REGNO_NREGS (regno, GET_MODE (dest)); | |
211 | while (--n > 0) | |
212 | CLEAR_REGNO_REG_SET (nonequal, regno + n); | |
213 | } | |
214 | } | |
8ecba28a | 215 | return false; |
5f0d2358 | 216 | |
8ecba28a JH |
217 | case SET: |
218 | if (rtx_equal_for_cselib_p (SET_DEST (exp), SET_SRC (exp))) | |
219 | return false; | |
9f16e871 JH |
220 | dest = SET_DEST (exp); |
221 | if (dest == pc_rtx) | |
222 | return false; | |
223 | if (!REG_P (dest)) | |
8ecba28a | 224 | return true; |
9f16e871 JH |
225 | regno = REGNO (dest); |
226 | SET_REGNO_REG_SET (nonequal, regno); | |
227 | if (regno < FIRST_PSEUDO_REGISTER) | |
228 | { | |
229 | int n = HARD_REGNO_NREGS (regno, GET_MODE (dest)); | |
230 | while (--n > 0) | |
231 | SET_REGNO_REG_SET (nonequal, regno + n); | |
232 | } | |
8ecba28a | 233 | return false; |
5f0d2358 | 234 | |
8ecba28a JH |
235 | default: |
236 | return false; | |
237 | } | |
238 | } | |
239 | /* Attempt to prove that the basic block B will have no side effects and | |
240 | allways continues in the same edge if reached via E. Return the edge | |
241 | if exist, NULL otherwise. */ | |
242 | ||
243 | static edge | |
244 | thread_jump (mode, e, b) | |
245 | int mode; | |
246 | edge e; | |
247 | basic_block b; | |
248 | { | |
249 | rtx set1, set2, cond1, cond2, insn; | |
250 | enum rtx_code code1, code2, reversed_code2; | |
251 | bool reverse1 = false; | |
252 | int i; | |
253 | regset nonequal; | |
254 | bool failed = false; | |
255 | ||
256 | /* At the moment, we do handle only conditional jumps, but later we may | |
257 | want to extend this code to tablejumps and others. */ | |
258 | if (!e->src->succ->succ_next || e->src->succ->succ_next->succ_next) | |
259 | return NULL; | |
260 | if (!b->succ || !b->succ->succ_next || b->succ->succ_next->succ_next) | |
261 | return NULL; | |
262 | ||
263 | /* Second branch must end with onlyjump, as we will eliminate the jump. */ | |
264 | if (!any_condjump_p (e->src->end) || !any_condjump_p (b->end) | |
265 | || !onlyjump_p (b->end)) | |
266 | return NULL; | |
267 | ||
268 | set1 = pc_set (e->src->end); | |
269 | set2 = pc_set (b->end); | |
270 | if (((e->flags & EDGE_FALLTHRU) != 0) | |
271 | != (XEXP (SET_SRC (set1), 0) == pc_rtx)) | |
272 | reverse1 = true; | |
273 | ||
274 | cond1 = XEXP (SET_SRC (set1), 0); | |
275 | cond2 = XEXP (SET_SRC (set2), 0); | |
276 | if (reverse1) | |
277 | code1 = reversed_comparison_code (cond1, b->end); | |
278 | else | |
279 | code1 = GET_CODE (cond1); | |
280 | ||
281 | code2 = GET_CODE (cond2); | |
282 | reversed_code2 = reversed_comparison_code (cond2, b->end); | |
283 | ||
284 | if (!comparison_dominates_p (code1, code2) | |
285 | && !comparison_dominates_p (code1, reversed_code2)) | |
286 | return NULL; | |
287 | ||
288 | /* Ensure that the comparison operators are equivalent. | |
289 | ??? This is far too pesimistic. We should allow swapped operands, | |
290 | different CCmodes, or for example comparisons for interval, that | |
291 | dominate even when operands are not equivalent. */ | |
292 | if (!rtx_equal_p (XEXP (cond1, 0), XEXP (cond2, 0)) | |
293 | || !rtx_equal_p (XEXP (cond1, 1), XEXP (cond2, 1))) | |
294 | return NULL; | |
295 | ||
296 | /* Short circuit cases where block B contains some side effects, as we can't | |
297 | safely bypass it. */ | |
298 | for (insn = NEXT_INSN (b->head); insn != NEXT_INSN (b->end); | |
299 | insn = NEXT_INSN (insn)) | |
300 | if (INSN_P (insn) && side_effects_p (PATTERN (insn))) | |
301 | return NULL; | |
302 | ||
303 | cselib_init (); | |
304 | ||
305 | /* First process all values computed in the source basic block. */ | |
306 | for (insn = NEXT_INSN (e->src->head); insn != NEXT_INSN (e->src->end); | |
307 | insn = NEXT_INSN (insn)) | |
308 | if (INSN_P (insn)) | |
309 | cselib_process_insn (insn); | |
310 | ||
311 | nonequal = BITMAP_XMALLOC(); | |
312 | CLEAR_REG_SET (nonequal); | |
5f0d2358 | 313 | |
8ecba28a JH |
314 | /* Now assume that we've continued by the edge E to B and continue |
315 | processing as if it were same basic block. | |
8ecba28a | 316 | Our goal is to prove that whole block is an NOOP. */ |
5f0d2358 | 317 | |
9f16e871 | 318 | for (insn = NEXT_INSN (b->head); insn != NEXT_INSN (b->end) && !failed; |
8ecba28a JH |
319 | insn = NEXT_INSN (insn)) |
320 | { | |
321 | if (INSN_P (insn)) | |
322 | { | |
323 | rtx pat = PATTERN (insn); | |
324 | ||
325 | if (GET_CODE (pat) == PARALLEL) | |
326 | { | |
327 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
328 | failed |= mark_effect (XVECEXP (pat, 0, i), nonequal); | |
329 | } | |
330 | else | |
331 | failed |= mark_effect (pat, nonequal); | |
332 | } | |
5f0d2358 | 333 | |
8ecba28a JH |
334 | cselib_process_insn (insn); |
335 | } | |
336 | ||
337 | /* Later we should clear nonequal of dead registers. So far we don't | |
338 | have life information in cfg_cleanup. */ | |
339 | if (failed) | |
340 | goto failed_exit; | |
341 | ||
342 | /* In case liveness information is available, we need to prove equivalence | |
343 | only of the live values. */ | |
344 | if (mode & CLEANUP_UPDATE_LIFE) | |
345 | AND_REG_SET (nonequal, b->global_live_at_end); | |
346 | ||
347 | EXECUTE_IF_SET_IN_REG_SET (nonequal, 0, i, goto failed_exit;); | |
348 | ||
349 | BITMAP_XFREE (nonequal); | |
350 | cselib_finish (); | |
351 | if ((comparison_dominates_p (code1, code2) != 0) | |
4deaa2f8 | 352 | != (XEXP (SET_SRC (set2), 1) == pc_rtx)) |
8ecba28a JH |
353 | return BRANCH_EDGE (b); |
354 | else | |
355 | return FALLTHRU_EDGE (b); | |
356 | ||
357 | failed_exit: | |
358 | BITMAP_XFREE (nonequal); | |
359 | cselib_finish (); | |
360 | return NULL; | |
361 | } | |
362 | \f | |
402209ff | 363 | /* Attempt to forward edges leaving basic block B. |
eaec9b3d | 364 | Return true if successful. */ |
402209ff JH |
365 | |
366 | static bool | |
367 | try_forward_edges (mode, b) | |
368 | basic_block b; | |
369 | int mode; | |
370 | { | |
371 | bool changed = false; | |
1c570418 JH |
372 | edge e, next, *threaded_edges = NULL; |
373 | int nthreaded_edges = 0; | |
402209ff | 374 | |
5f0d2358 | 375 | for (e = b->succ; e; e = next) |
402209ff JH |
376 | { |
377 | basic_block target, first; | |
378 | int counter; | |
8ecba28a | 379 | bool threaded = false; |
402209ff JH |
380 | |
381 | next = e->succ_next; | |
382 | ||
383 | /* Skip complex edges because we don't know how to update them. | |
384 | ||
eaec9b3d | 385 | Still handle fallthru edges, as we can succeed to forward fallthru |
402209ff | 386 | edge to the same place as the branch edge of conditional branch |
eaec9b3d | 387 | and turn conditional branch to an unconditional branch. */ |
402209ff JH |
388 | if (e->flags & EDGE_COMPLEX) |
389 | continue; | |
390 | ||
391 | target = first = e->dest; | |
392 | counter = 0; | |
393 | ||
8ecba28a | 394 | while (counter < n_basic_blocks) |
402209ff | 395 | { |
8ecba28a JH |
396 | basic_block new_target = NULL; |
397 | bool new_target_threaded = false; | |
398 | ||
399 | if (FORWARDER_BLOCK_P (target) | |
400 | && target->succ->dest != EXIT_BLOCK_PTR) | |
401 | { | |
402 | /* Bypass trivial infinite loops. */ | |
403 | if (target == target->succ->dest) | |
404 | counter = n_basic_blocks; | |
405 | new_target = target->succ->dest; | |
406 | } | |
5f0d2358 | 407 | |
8ecba28a JH |
408 | /* Allow to thread only over one edge at time to simplify updating |
409 | of probabilities. */ | |
1c570418 | 410 | else if (mode & CLEANUP_THREADING) |
8ecba28a | 411 | { |
1c570418 JH |
412 | edge t = thread_jump (mode, e, target); |
413 | if (t) | |
8ecba28a | 414 | { |
1c570418 JH |
415 | if (!nthreaded_edges) |
416 | threaded_edges = xmalloc (sizeof (*threaded_edges) | |
417 | * n_basic_blocks); | |
3b3b1e32 RH |
418 | else |
419 | { | |
420 | int i; | |
421 | ||
422 | /* Detect an infinite loop across blocks not | |
423 | including the start block. */ | |
424 | for (i = 0; i < nthreaded_edges; ++i) | |
425 | if (threaded_edges[i] == t) | |
426 | break; | |
427 | if (i < nthreaded_edges) | |
428 | break; | |
429 | } | |
430 | ||
431 | /* Detect an infinite loop across the start block. */ | |
432 | if (t->dest == b) | |
433 | break; | |
434 | ||
435 | if (nthreaded_edges >= n_basic_blocks) | |
436 | abort (); | |
1c570418 | 437 | threaded_edges[nthreaded_edges++] = t; |
3b3b1e32 RH |
438 | |
439 | new_target = t->dest; | |
440 | new_target_threaded = true; | |
8ecba28a JH |
441 | } |
442 | } | |
5f0d2358 | 443 | |
8ecba28a JH |
444 | if (!new_target) |
445 | break; | |
402209ff JH |
446 | |
447 | /* Avoid killing of loop pre-headers, as it is the place loop | |
448 | optimizer wants to hoist code to. | |
449 | ||
450 | For fallthru forwarders, the LOOP_BEG note must appear between | |
451 | the header of block and CODE_LABEL of the loop, for non forwarders | |
452 | it must appear before the JUMP_INSN. */ | |
453 | if (mode & CLEANUP_PRE_LOOP) | |
454 | { | |
455 | rtx insn = (target->succ->flags & EDGE_FALLTHRU | |
456 | ? target->head : prev_nonnote_insn (target->end)); | |
457 | ||
458 | if (GET_CODE (insn) != NOTE) | |
459 | insn = NEXT_INSN (insn); | |
460 | ||
5f0d2358 | 461 | for (; insn && GET_CODE (insn) != CODE_LABEL && !INSN_P (insn); |
402209ff JH |
462 | insn = NEXT_INSN (insn)) |
463 | if (GET_CODE (insn) == NOTE | |
464 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) | |
465 | break; | |
466 | ||
467 | if (GET_CODE (insn) == NOTE) | |
468 | break; | |
469 | } | |
5f0d2358 | 470 | |
8ecba28a JH |
471 | counter++; |
472 | target = new_target; | |
473 | threaded |= new_target_threaded; | |
474 | } | |
402209ff JH |
475 | |
476 | if (counter >= n_basic_blocks) | |
477 | { | |
478 | if (rtl_dump_file) | |
479 | fprintf (rtl_dump_file, "Infinite loop in BB %i.\n", | |
480 | target->index); | |
481 | } | |
482 | else if (target == first) | |
483 | ; /* We didn't do anything. */ | |
484 | else | |
485 | { | |
486 | /* Save the values now, as the edge may get removed. */ | |
487 | gcov_type edge_count = e->count; | |
488 | int edge_probability = e->probability; | |
8ecba28a | 489 | int edge_frequency; |
1c570418 | 490 | int n = 0; |
402209ff | 491 | |
6ee3c8e4 JJ |
492 | /* Don't force if target is exit block. */ |
493 | if (threaded && target != EXIT_BLOCK_PTR) | |
402209ff | 494 | { |
8ecba28a JH |
495 | notice_new_block (redirect_edge_and_branch_force (e, target)); |
496 | if (rtl_dump_file) | |
497 | fprintf (rtl_dump_file, "Conditionals threaded.\n"); | |
402209ff | 498 | } |
8ecba28a | 499 | else if (!redirect_edge_and_branch (e, target)) |
402209ff JH |
500 | { |
501 | if (rtl_dump_file) | |
5f0d2358 RK |
502 | fprintf (rtl_dump_file, |
503 | "Forwarding edge %i->%i to %i failed.\n", | |
402209ff | 504 | b->index, e->dest->index, target->index); |
8ecba28a | 505 | continue; |
402209ff | 506 | } |
5f0d2358 | 507 | |
8ecba28a JH |
508 | /* We successfully forwarded the edge. Now update profile |
509 | data: for each edge we traversed in the chain, remove | |
510 | the original edge's execution count. */ | |
511 | edge_frequency = ((edge_probability * b->frequency | |
512 | + REG_BR_PROB_BASE / 2) | |
513 | / REG_BR_PROB_BASE); | |
514 | ||
515 | if (!FORWARDER_BLOCK_P (b) && forwarder_block_p (b)) | |
516 | BB_SET_FLAG (b, BB_FORWARDER_BLOCK); | |
517 | BB_SET_FLAG (b, BB_UPDATE_LIFE); | |
518 | ||
519 | do | |
520 | { | |
521 | edge t; | |
5f0d2358 | 522 | |
8ecba28a JH |
523 | first->count -= edge_count; |
524 | first->succ->count -= edge_count; | |
525 | first->frequency -= edge_frequency; | |
526 | if (first->succ->succ_next) | |
3b3b1e32 RH |
527 | { |
528 | if (n >= nthreaded_edges) | |
529 | abort (); | |
530 | t = threaded_edges [n++]; | |
531 | } | |
8ecba28a JH |
532 | else |
533 | t = first->succ; | |
5f0d2358 | 534 | |
8ecba28a JH |
535 | first = t->dest; |
536 | } | |
537 | while (first != target); | |
538 | ||
539 | changed = true; | |
402209ff JH |
540 | } |
541 | } | |
542 | ||
1c570418 JH |
543 | if (threaded_edges) |
544 | free (threaded_edges); | |
402209ff JH |
545 | return changed; |
546 | } | |
547 | \f | |
ec10f7c7 RH |
548 | /* Return true if LABEL is a target of JUMP_INSN. This applies only |
549 | to non-complex jumps. That is, direct unconditional, conditional, | |
550 | and tablejumps, but not computed jumps or returns. It also does | |
551 | not apply to the fallthru case of a conditional jump. */ | |
552 | ||
553 | static bool | |
554 | label_is_jump_target_p (label, jump_insn) | |
555 | rtx label, jump_insn; | |
556 | { | |
557 | rtx tmp = JUMP_LABEL (jump_insn); | |
558 | ||
559 | if (label == tmp) | |
560 | return true; | |
561 | ||
562 | if (tmp != NULL_RTX | |
563 | && (tmp = NEXT_INSN (tmp)) != NULL_RTX | |
564 | && GET_CODE (tmp) == JUMP_INSN | |
565 | && (tmp = PATTERN (tmp), | |
566 | GET_CODE (tmp) == ADDR_VEC | |
567 | || GET_CODE (tmp) == ADDR_DIFF_VEC)) | |
568 | { | |
569 | rtvec vec = XVEC (tmp, GET_CODE (tmp) == ADDR_DIFF_VEC); | |
570 | int i, veclen = GET_NUM_ELEM (vec); | |
571 | ||
572 | for (i = 0; i < veclen; ++i) | |
573 | if (XEXP (RTVEC_ELT (vec, i), 0) == label) | |
574 | return true; | |
575 | } | |
576 | ||
577 | return false; | |
578 | } | |
579 | ||
4262e623 JH |
580 | /* Return true if LABEL is used for tail recursion. */ |
581 | ||
582 | static bool | |
402209ff JH |
583 | tail_recursion_label_p (label) |
584 | rtx label; | |
585 | { | |
586 | rtx x; | |
587 | ||
588 | for (x = tail_recursion_label_list; x; x = XEXP (x, 1)) | |
589 | if (label == XEXP (x, 0)) | |
4262e623 | 590 | return true; |
402209ff | 591 | |
4262e623 | 592 | return false; |
402209ff JH |
593 | } |
594 | ||
595 | /* Blocks A and B are to be merged into a single block. A has no incoming | |
596 | fallthru edge, so it can be moved before B without adding or modifying | |
597 | any jumps (aside from the jump from A to B). */ | |
598 | ||
4262e623 | 599 | static void |
402209ff JH |
600 | merge_blocks_move_predecessor_nojumps (a, b) |
601 | basic_block a, b; | |
602 | { | |
603 | rtx barrier; | |
604 | int index; | |
605 | ||
606 | barrier = next_nonnote_insn (a->end); | |
607 | if (GET_CODE (barrier) != BARRIER) | |
608 | abort (); | |
53c17031 | 609 | delete_insn (barrier); |
402209ff JH |
610 | |
611 | /* Move block and loop notes out of the chain so that we do not | |
612 | disturb their order. | |
613 | ||
614 | ??? A better solution would be to squeeze out all the non-nested notes | |
615 | and adjust the block trees appropriately. Even better would be to have | |
616 | a tighter connection between block trees and rtl so that this is not | |
617 | necessary. */ | |
2b7d71b2 JJ |
618 | if (squeeze_notes (&a->head, &a->end)) |
619 | abort (); | |
402209ff JH |
620 | |
621 | /* Scramble the insn chain. */ | |
622 | if (a->end != PREV_INSN (b->head)) | |
3c030e88 | 623 | reorder_insns_nobb (a->head, a->end, PREV_INSN (b->head)); |
7dddfb65 | 624 | BB_SET_FLAG (a, BB_UPDATE_LIFE); |
402209ff JH |
625 | |
626 | if (rtl_dump_file) | |
5f0d2358 RK |
627 | fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n", |
628 | a->index, b->index); | |
402209ff JH |
629 | |
630 | /* Swap the records for the two blocks around. Although we are deleting B, | |
631 | A is now where B was and we want to compact the BB array from where | |
632 | A used to be. */ | |
633 | BASIC_BLOCK (a->index) = b; | |
634 | BASIC_BLOCK (b->index) = a; | |
635 | index = a->index; | |
636 | a->index = b->index; | |
637 | b->index = index; | |
638 | ||
639 | /* Now blocks A and B are contiguous. Merge them. */ | |
640 | merge_blocks_nomove (a, b); | |
402209ff JH |
641 | } |
642 | ||
643 | /* Blocks A and B are to be merged into a single block. B has no outgoing | |
644 | fallthru edge, so it can be moved after A without adding or modifying | |
645 | any jumps (aside from the jump from A to B). */ | |
646 | ||
4262e623 | 647 | static void |
402209ff JH |
648 | merge_blocks_move_successor_nojumps (a, b) |
649 | basic_block a, b; | |
650 | { | |
f62ce55b | 651 | rtx barrier, real_b_end; |
402209ff | 652 | |
f62ce55b | 653 | real_b_end = b->end; |
402209ff JH |
654 | barrier = NEXT_INSN (b->end); |
655 | ||
656 | /* Recognize a jump table following block B. */ | |
657 | if (barrier | |
658 | && GET_CODE (barrier) == CODE_LABEL | |
659 | && NEXT_INSN (barrier) | |
660 | && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN | |
661 | && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC | |
662 | || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC)) | |
663 | { | |
f62ce55b RE |
664 | /* Temporarily add the table jump insn to b, so that it will also |
665 | be moved to the correct location. */ | |
402209ff JH |
666 | b->end = NEXT_INSN (barrier); |
667 | barrier = NEXT_INSN (b->end); | |
668 | } | |
669 | ||
670 | /* There had better have been a barrier there. Delete it. */ | |
671 | if (barrier && GET_CODE (barrier) == BARRIER) | |
53c17031 | 672 | delete_insn (barrier); |
402209ff JH |
673 | |
674 | /* Move block and loop notes out of the chain so that we do not | |
675 | disturb their order. | |
676 | ||
677 | ??? A better solution would be to squeeze out all the non-nested notes | |
678 | and adjust the block trees appropriately. Even better would be to have | |
679 | a tighter connection between block trees and rtl so that this is not | |
680 | necessary. */ | |
2b7d71b2 JJ |
681 | if (squeeze_notes (&b->head, &b->end)) |
682 | abort (); | |
402209ff JH |
683 | |
684 | /* Scramble the insn chain. */ | |
3c030e88 | 685 | reorder_insns_nobb (b->head, b->end, a->end); |
402209ff | 686 | |
f62ce55b RE |
687 | /* Restore the real end of b. */ |
688 | b->end = real_b_end; | |
689 | ||
402209ff JH |
690 | /* Now blocks A and B are contiguous. Merge them. */ |
691 | merge_blocks_nomove (a, b); | |
7dddfb65 | 692 | BB_SET_FLAG (a, BB_UPDATE_LIFE); |
402209ff JH |
693 | |
694 | if (rtl_dump_file) | |
5f0d2358 RK |
695 | fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n", |
696 | b->index, a->index); | |
402209ff JH |
697 | } |
698 | ||
699 | /* Attempt to merge basic blocks that are potentially non-adjacent. | |
700 | Return true iff the attempt succeeded. */ | |
701 | ||
4262e623 | 702 | static bool |
402209ff JH |
703 | merge_blocks (e, b, c, mode) |
704 | edge e; | |
705 | basic_block b, c; | |
706 | int mode; | |
707 | { | |
708 | /* If C has a tail recursion label, do not merge. There is no | |
709 | edge recorded from the call_placeholder back to this label, as | |
710 | that would make optimize_sibling_and_tail_recursive_calls more | |
711 | complex for no gain. */ | |
4262e623 JH |
712 | if ((mode & CLEANUP_PRE_SIBCALL) |
713 | && GET_CODE (c->head) == CODE_LABEL | |
402209ff | 714 | && tail_recursion_label_p (c->head)) |
4262e623 | 715 | return false; |
402209ff JH |
716 | |
717 | /* If B has a fallthru edge to C, no need to move anything. */ | |
718 | if (e->flags & EDGE_FALLTHRU) | |
719 | { | |
473fb060 JH |
720 | /* We need to update liveness in case C already has broken liveness |
721 | or B ends by conditional jump to next instructions that will be | |
722 | removed. */ | |
723 | if ((BB_FLAGS (c) & BB_UPDATE_LIFE) | |
724 | || GET_CODE (b->end) == JUMP_INSN) | |
725 | BB_SET_FLAG (b, BB_UPDATE_LIFE); | |
402209ff | 726 | merge_blocks_nomove (b, c); |
635559ab | 727 | update_forwarder_flag (b); |
402209ff JH |
728 | |
729 | if (rtl_dump_file) | |
5f0d2358 RK |
730 | fprintf (rtl_dump_file, "Merged %d and %d without moving.\n", |
731 | b->index, c->index); | |
402209ff | 732 | |
4262e623 | 733 | return true; |
402209ff | 734 | } |
5f0d2358 | 735 | |
402209ff JH |
736 | /* Otherwise we will need to move code around. Do that only if expensive |
737 | transformations are allowed. */ | |
738 | else if (mode & CLEANUP_EXPENSIVE) | |
739 | { | |
4262e623 JH |
740 | edge tmp_edge, b_fallthru_edge; |
741 | bool c_has_outgoing_fallthru; | |
742 | bool b_has_incoming_fallthru; | |
402209ff JH |
743 | |
744 | /* Avoid overactive code motion, as the forwarder blocks should be | |
745 | eliminated by edge redirection instead. One exception might have | |
746 | been if B is a forwarder block and C has no fallthru edge, but | |
747 | that should be cleaned up by bb-reorder instead. */ | |
635559ab | 748 | if (FORWARDER_BLOCK_P (b) || FORWARDER_BLOCK_P (c)) |
4262e623 | 749 | return false; |
402209ff JH |
750 | |
751 | /* We must make sure to not munge nesting of lexical blocks, | |
752 | and loop notes. This is done by squeezing out all the notes | |
753 | and leaving them there to lie. Not ideal, but functional. */ | |
754 | ||
755 | for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next) | |
756 | if (tmp_edge->flags & EDGE_FALLTHRU) | |
757 | break; | |
5f0d2358 | 758 | |
402209ff | 759 | c_has_outgoing_fallthru = (tmp_edge != NULL); |
402209ff JH |
760 | |
761 | for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next) | |
762 | if (tmp_edge->flags & EDGE_FALLTHRU) | |
763 | break; | |
5f0d2358 | 764 | |
402209ff | 765 | b_has_incoming_fallthru = (tmp_edge != NULL); |
4262e623 JH |
766 | b_fallthru_edge = tmp_edge; |
767 | ||
768 | /* Otherwise, we're going to try to move C after B. If C does | |
769 | not have an outgoing fallthru, then it can be moved | |
770 | immediately after B without introducing or modifying jumps. */ | |
771 | if (! c_has_outgoing_fallthru) | |
772 | { | |
773 | merge_blocks_move_successor_nojumps (b, c); | |
774 | return true; | |
775 | } | |
402209ff JH |
776 | |
777 | /* If B does not have an incoming fallthru, then it can be moved | |
778 | immediately before C without introducing or modifying jumps. | |
779 | C cannot be the first block, so we do not have to worry about | |
780 | accessing a non-existent block. */ | |
402209ff | 781 | |
4262e623 JH |
782 | if (b_has_incoming_fallthru) |
783 | { | |
473fb060 | 784 | basic_block bb; |
5f0d2358 | 785 | |
4262e623 JH |
786 | if (b_fallthru_edge->src == ENTRY_BLOCK_PTR) |
787 | return false; | |
7dddfb65 JH |
788 | bb = force_nonfallthru (b_fallthru_edge); |
789 | if (bb) | |
790 | notice_new_block (bb); | |
791 | else | |
792 | BB_SET_FLAG (b_fallthru_edge->src, BB_UPDATE_LIFE); | |
4262e623 | 793 | } |
5f0d2358 | 794 | |
4262e623 JH |
795 | merge_blocks_move_predecessor_nojumps (b, c); |
796 | return true; | |
402209ff | 797 | } |
5f0d2358 | 798 | |
4262e623 | 799 | return false; |
402209ff JH |
800 | } |
801 | \f | |
0dd0e980 JH |
802 | |
803 | /* Return true if I1 and I2 are equivalent and thus can be crossjumped. */ | |
804 | ||
805 | static bool | |
806 | insns_match_p (mode, i1, i2) | |
88f92c0f | 807 | int mode ATTRIBUTE_UNUSED; |
0dd0e980 JH |
808 | rtx i1, i2; |
809 | { | |
810 | rtx p1, p2; | |
811 | ||
812 | /* Verify that I1 and I2 are equivalent. */ | |
813 | if (GET_CODE (i1) != GET_CODE (i2)) | |
814 | return false; | |
815 | ||
816 | p1 = PATTERN (i1); | |
817 | p2 = PATTERN (i2); | |
818 | ||
819 | if (GET_CODE (p1) != GET_CODE (p2)) | |
820 | return false; | |
821 | ||
822 | /* If this is a CALL_INSN, compare register usage information. | |
823 | If we don't check this on stack register machines, the two | |
824 | CALL_INSNs might be merged leaving reg-stack.c with mismatching | |
825 | numbers of stack registers in the same basic block. | |
826 | If we don't check this on machines with delay slots, a delay slot may | |
827 | be filled that clobbers a parameter expected by the subroutine. | |
828 | ||
829 | ??? We take the simple route for now and assume that if they're | |
830 | equal, they were constructed identically. */ | |
831 | ||
832 | if (GET_CODE (i1) == CALL_INSN | |
833 | && !rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1), | |
834 | CALL_INSN_FUNCTION_USAGE (i2))) | |
835 | return false; | |
836 | ||
837 | #ifdef STACK_REGS | |
838 | /* If cross_jump_death_matters is not 0, the insn's mode | |
839 | indicates whether or not the insn contains any stack-like | |
840 | regs. */ | |
841 | ||
842 | if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1)) | |
843 | { | |
844 | /* If register stack conversion has already been done, then | |
845 | death notes must also be compared before it is certain that | |
846 | the two instruction streams match. */ | |
847 | ||
848 | rtx note; | |
849 | HARD_REG_SET i1_regset, i2_regset; | |
850 | ||
851 | CLEAR_HARD_REG_SET (i1_regset); | |
852 | CLEAR_HARD_REG_SET (i2_regset); | |
853 | ||
854 | for (note = REG_NOTES (i1); note; note = XEXP (note, 1)) | |
855 | if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) | |
856 | SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0))); | |
857 | ||
858 | for (note = REG_NOTES (i2); note; note = XEXP (note, 1)) | |
859 | if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) | |
860 | SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0))); | |
861 | ||
862 | GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done); | |
863 | ||
864 | return false; | |
865 | ||
866 | done: | |
867 | ; | |
868 | } | |
869 | #endif | |
870 | ||
871 | if (reload_completed | |
872 | ? ! rtx_renumbered_equal_p (p1, p2) : ! rtx_equal_p (p1, p2)) | |
873 | { | |
874 | /* The following code helps take care of G++ cleanups. */ | |
875 | rtx equiv1 = find_reg_equal_equiv_note (i1); | |
876 | rtx equiv2 = find_reg_equal_equiv_note (i2); | |
877 | ||
878 | if (equiv1 && equiv2 | |
879 | /* If the equivalences are not to a constant, they may | |
880 | reference pseudos that no longer exist, so we can't | |
881 | use them. */ | |
882 | && (! reload_completed | |
883 | || (CONSTANT_P (XEXP (equiv1, 0)) | |
884 | && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0))))) | |
885 | { | |
886 | rtx s1 = single_set (i1); | |
887 | rtx s2 = single_set (i2); | |
888 | if (s1 != 0 && s2 != 0 | |
889 | && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2))) | |
890 | { | |
891 | validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1); | |
892 | validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1); | |
893 | if (! rtx_renumbered_equal_p (p1, p2)) | |
894 | cancel_changes (0); | |
895 | else if (apply_change_group ()) | |
896 | return true; | |
897 | } | |
898 | } | |
5f0d2358 | 899 | |
0dd0e980 JH |
900 | return false; |
901 | } | |
5f0d2358 | 902 | |
0dd0e980 JH |
903 | return true; |
904 | } | |
905 | \f | |
402209ff JH |
906 | /* Look through the insns at the end of BB1 and BB2 and find the longest |
907 | sequence that are equivalent. Store the first insns for that sequence | |
908 | in *F1 and *F2 and return the sequence length. | |
909 | ||
910 | To simplify callers of this function, if the blocks match exactly, | |
911 | store the head of the blocks in *F1 and *F2. */ | |
912 | ||
913 | static int | |
914 | flow_find_cross_jump (mode, bb1, bb2, f1, f2) | |
915 | int mode ATTRIBUTE_UNUSED; | |
916 | basic_block bb1, bb2; | |
917 | rtx *f1, *f2; | |
918 | { | |
0dd0e980 | 919 | rtx i1, i2, last1, last2, afterlast1, afterlast2; |
402209ff JH |
920 | int ninsns = 0; |
921 | ||
922 | /* Skip simple jumps at the end of the blocks. Complex jumps still | |
923 | need to be compared for equivalence, which we'll do below. */ | |
924 | ||
925 | i1 = bb1->end; | |
08f7f057 | 926 | last1 = afterlast1 = last2 = afterlast2 = NULL_RTX; |
402209ff JH |
927 | if (onlyjump_p (i1) |
928 | || (returnjump_p (i1) && !side_effects_p (PATTERN (i1)))) | |
08f7f057 JH |
929 | { |
930 | last1 = i1; | |
08f7f057 JH |
931 | i1 = PREV_INSN (i1); |
932 | } | |
5f0d2358 | 933 | |
402209ff JH |
934 | i2 = bb2->end; |
935 | if (onlyjump_p (i2) | |
936 | || (returnjump_p (i2) && !side_effects_p (PATTERN (i2)))) | |
08f7f057 JH |
937 | { |
938 | last2 = i2; | |
d1ee6d9b JH |
939 | /* Count everything except for unconditional jump as insn. */ |
940 | if (!simplejump_p (i2) && !returnjump_p (i2) && last1) | |
941 | ninsns++; | |
08f7f057 JH |
942 | i2 = PREV_INSN (i2); |
943 | } | |
402209ff | 944 | |
402209ff JH |
945 | while (true) |
946 | { | |
947 | /* Ignore notes. */ | |
08f7f057 | 948 | while (!active_insn_p (i1) && i1 != bb1->head) |
402209ff | 949 | i1 = PREV_INSN (i1); |
5f0d2358 | 950 | |
08f7f057 | 951 | while (!active_insn_p (i2) && i2 != bb2->head) |
402209ff JH |
952 | i2 = PREV_INSN (i2); |
953 | ||
954 | if (i1 == bb1->head || i2 == bb2->head) | |
955 | break; | |
956 | ||
0dd0e980 | 957 | if (!insns_match_p (mode, i1, i2)) |
402209ff JH |
958 | break; |
959 | ||
402209ff | 960 | /* Don't begin a cross-jump with a USE or CLOBBER insn. */ |
0dd0e980 | 961 | if (active_insn_p (i1)) |
402209ff | 962 | { |
7106d491 RE |
963 | /* If the merged insns have different REG_EQUAL notes, then |
964 | remove them. */ | |
965 | rtx equiv1 = find_reg_equal_equiv_note (i1); | |
966 | rtx equiv2 = find_reg_equal_equiv_note (i2); | |
967 | ||
968 | if (equiv1 && !equiv2) | |
969 | remove_note (i1, equiv1); | |
970 | else if (!equiv1 && equiv2) | |
971 | remove_note (i2, equiv2); | |
972 | else if (equiv1 && equiv2 | |
973 | && !rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0))) | |
974 | { | |
975 | remove_note (i1, equiv1); | |
976 | remove_note (i2, equiv2); | |
977 | } | |
978 | ||
402209ff JH |
979 | afterlast1 = last1, afterlast2 = last2; |
980 | last1 = i1, last2 = i2; | |
981 | ninsns++; | |
982 | } | |
5f0d2358 | 983 | |
402209ff JH |
984 | i1 = PREV_INSN (i1); |
985 | i2 = PREV_INSN (i2); | |
986 | } | |
987 | ||
988 | #ifdef HAVE_cc0 | |
5f0d2358 RK |
989 | /* Don't allow the insn after a compare to be shared by |
990 | cross-jumping unless the compare is also shared. */ | |
991 | if (ninsns && reg_mentioned_p (cc0_rtx, last1) && ! sets_cc0_p (last1)) | |
992 | last1 = afterlast1, last2 = afterlast2, ninsns--; | |
402209ff JH |
993 | #endif |
994 | ||
eaec9b3d | 995 | /* Include preceding notes and labels in the cross-jump. One, |
402209ff JH |
996 | this may bring us to the head of the blocks as requested above. |
997 | Two, it keeps line number notes as matched as may be. */ | |
998 | if (ninsns) | |
999 | { | |
08f7f057 | 1000 | while (last1 != bb1->head && !active_insn_p (PREV_INSN (last1))) |
402209ff | 1001 | last1 = PREV_INSN (last1); |
5f0d2358 | 1002 | |
402209ff JH |
1003 | if (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == CODE_LABEL) |
1004 | last1 = PREV_INSN (last1); | |
5f0d2358 | 1005 | |
08f7f057 | 1006 | while (last2 != bb2->head && !active_insn_p (PREV_INSN (last2))) |
402209ff | 1007 | last2 = PREV_INSN (last2); |
5f0d2358 | 1008 | |
402209ff JH |
1009 | if (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == CODE_LABEL) |
1010 | last2 = PREV_INSN (last2); | |
1011 | ||
1012 | *f1 = last1; | |
1013 | *f2 = last2; | |
1014 | } | |
1015 | ||
1016 | return ninsns; | |
1017 | } | |
1018 | ||
1019 | /* Return true iff outgoing edges of BB1 and BB2 match, together with | |
1020 | the branch instruction. This means that if we commonize the control | |
1021 | flow before end of the basic block, the semantic remains unchanged. | |
1022 | ||
1023 | We may assume that there exists one edge with a common destination. */ | |
1024 | ||
1025 | static bool | |
0dd0e980 JH |
1026 | outgoing_edges_match (mode, bb1, bb2) |
1027 | int mode; | |
402209ff JH |
1028 | basic_block bb1; |
1029 | basic_block bb2; | |
1030 | { | |
0dd0e980 JH |
1031 | int nehedges1 = 0, nehedges2 = 0; |
1032 | edge fallthru1 = 0, fallthru2 = 0; | |
1033 | edge e1, e2; | |
1034 | ||
c04cf67b RH |
1035 | /* If BB1 has only one successor, we may be looking at either an |
1036 | unconditional jump, or a fake edge to exit. */ | |
d1ee6d9b JH |
1037 | if (bb1->succ && !bb1->succ->succ_next |
1038 | && !(bb1->succ->flags & (EDGE_COMPLEX | EDGE_FAKE))) | |
5f0d2358 RK |
1039 | return (bb2->succ && !bb2->succ->succ_next |
1040 | && (bb2->succ->flags & (EDGE_COMPLEX | EDGE_FAKE)) == 0); | |
402209ff JH |
1041 | |
1042 | /* Match conditional jumps - this may get tricky when fallthru and branch | |
1043 | edges are crossed. */ | |
1044 | if (bb1->succ | |
1045 | && bb1->succ->succ_next | |
1046 | && !bb1->succ->succ_next->succ_next | |
d1ee6d9b JH |
1047 | && any_condjump_p (bb1->end) |
1048 | && onlyjump_p (bb1->end)) | |
402209ff JH |
1049 | { |
1050 | edge b1, f1, b2, f2; | |
1051 | bool reverse, match; | |
1052 | rtx set1, set2, cond1, cond2; | |
1053 | enum rtx_code code1, code2; | |
1054 | ||
1055 | if (!bb2->succ | |
1056 | || !bb2->succ->succ_next | |
1057 | || bb1->succ->succ_next->succ_next | |
d1ee6d9b JH |
1058 | || !any_condjump_p (bb2->end) |
1059 | || !onlyjump_p (bb1->end)) | |
402209ff JH |
1060 | return false; |
1061 | ||
1062 | b1 = BRANCH_EDGE (bb1); | |
1063 | b2 = BRANCH_EDGE (bb2); | |
1064 | f1 = FALLTHRU_EDGE (bb1); | |
1065 | f2 = FALLTHRU_EDGE (bb2); | |
1066 | ||
1067 | /* Get around possible forwarders on fallthru edges. Other cases | |
1068 | should be optimized out already. */ | |
635559ab | 1069 | if (FORWARDER_BLOCK_P (f1->dest)) |
402209ff | 1070 | f1 = f1->dest->succ; |
5f0d2358 | 1071 | |
635559ab | 1072 | if (FORWARDER_BLOCK_P (f2->dest)) |
402209ff JH |
1073 | f2 = f2->dest->succ; |
1074 | ||
1075 | /* To simplify use of this function, return false if there are | |
1076 | unneeded forwarder blocks. These will get eliminated later | |
1077 | during cleanup_cfg. */ | |
635559ab JH |
1078 | if (FORWARDER_BLOCK_P (f1->dest) |
1079 | || FORWARDER_BLOCK_P (f2->dest) | |
1080 | || FORWARDER_BLOCK_P (b1->dest) | |
1081 | || FORWARDER_BLOCK_P (b2->dest)) | |
402209ff JH |
1082 | return false; |
1083 | ||
1084 | if (f1->dest == f2->dest && b1->dest == b2->dest) | |
1085 | reverse = false; | |
1086 | else if (f1->dest == b2->dest && b1->dest == f2->dest) | |
1087 | reverse = true; | |
1088 | else | |
1089 | return false; | |
1090 | ||
1091 | set1 = pc_set (bb1->end); | |
1092 | set2 = pc_set (bb2->end); | |
1093 | if ((XEXP (SET_SRC (set1), 1) == pc_rtx) | |
1094 | != (XEXP (SET_SRC (set2), 1) == pc_rtx)) | |
1095 | reverse = !reverse; | |
1096 | ||
1097 | cond1 = XEXP (SET_SRC (set1), 0); | |
1098 | cond2 = XEXP (SET_SRC (set2), 0); | |
1099 | code1 = GET_CODE (cond1); | |
1100 | if (reverse) | |
1101 | code2 = reversed_comparison_code (cond2, bb2->end); | |
1102 | else | |
1103 | code2 = GET_CODE (cond2); | |
5f0d2358 | 1104 | |
402209ff JH |
1105 | if (code2 == UNKNOWN) |
1106 | return false; | |
1107 | ||
1108 | /* Verify codes and operands match. */ | |
1109 | match = ((code1 == code2 | |
1110 | && rtx_renumbered_equal_p (XEXP (cond1, 0), XEXP (cond2, 0)) | |
1111 | && rtx_renumbered_equal_p (XEXP (cond1, 1), XEXP (cond2, 1))) | |
1112 | || (code1 == swap_condition (code2) | |
1113 | && rtx_renumbered_equal_p (XEXP (cond1, 1), | |
1114 | XEXP (cond2, 0)) | |
1115 | && rtx_renumbered_equal_p (XEXP (cond1, 0), | |
1116 | XEXP (cond2, 1)))); | |
1117 | ||
1118 | /* If we return true, we will join the blocks. Which means that | |
1119 | we will only have one branch prediction bit to work with. Thus | |
1120 | we require the existing branches to have probabilities that are | |
1121 | roughly similar. */ | |
1122 | /* ??? We should use bb->frequency to allow merging in infrequently | |
1123 | executed blocks, but at the moment it is not available when | |
1124 | cleanup_cfg is run. */ | |
1125 | if (match && !optimize_size) | |
1126 | { | |
1127 | rtx note1, note2; | |
1128 | int prob1, prob2; | |
5f0d2358 | 1129 | |
402209ff JH |
1130 | note1 = find_reg_note (bb1->end, REG_BR_PROB, 0); |
1131 | note2 = find_reg_note (bb2->end, REG_BR_PROB, 0); | |
1132 | ||
1133 | if (note1 && note2) | |
1134 | { | |
1135 | prob1 = INTVAL (XEXP (note1, 0)); | |
1136 | prob2 = INTVAL (XEXP (note2, 0)); | |
1137 | if (reverse) | |
1138 | prob2 = REG_BR_PROB_BASE - prob2; | |
1139 | ||
1140 | /* Fail if the difference in probabilities is | |
1141 | greater than 5%. */ | |
1142 | if (abs (prob1 - prob2) > REG_BR_PROB_BASE / 20) | |
1143 | return false; | |
1144 | } | |
5f0d2358 | 1145 | |
402209ff JH |
1146 | else if (note1 || note2) |
1147 | return false; | |
1148 | } | |
1149 | ||
1150 | if (rtl_dump_file && match) | |
1151 | fprintf (rtl_dump_file, "Conditionals in bb %i and %i match.\n", | |
1152 | bb1->index, bb2->index); | |
1153 | ||
1154 | return match; | |
1155 | } | |
1156 | ||
0dd0e980 JH |
1157 | /* Generic case - we are seeing an computed jump, table jump or trapping |
1158 | instruction. */ | |
1159 | ||
1160 | /* First ensure that the instructions match. There may be many outgoing | |
1161 | edges so this test is generally cheaper. | |
1162 | ??? Currently the tablejumps will never match, as they do have | |
1163 | different tables. */ | |
1164 | if (!insns_match_p (mode, bb1->end, bb2->end)) | |
1165 | return false; | |
1166 | ||
1167 | /* Search the outgoing edges, ensure that the counts do match, find possible | |
1168 | fallthru and exception handling edges since these needs more | |
1169 | validation. */ | |
1170 | for (e1 = bb1->succ, e2 = bb2->succ; e1 && e2; | |
1171 | e1 = e1->succ_next, e2 = e2->succ_next) | |
1172 | { | |
1173 | if (e1->flags & EDGE_EH) | |
1174 | nehedges1++; | |
5f0d2358 | 1175 | |
0dd0e980 JH |
1176 | if (e2->flags & EDGE_EH) |
1177 | nehedges2++; | |
5f0d2358 | 1178 | |
0dd0e980 JH |
1179 | if (e1->flags & EDGE_FALLTHRU) |
1180 | fallthru1 = e1; | |
1181 | if (e2->flags & EDGE_FALLTHRU) | |
1182 | fallthru2 = e2; | |
1183 | } | |
5f0d2358 | 1184 | |
0dd0e980 | 1185 | /* If number of edges of various types does not match, fail. */ |
5f0d2358 RK |
1186 | if (e1 || e2 |
1187 | || nehedges1 != nehedges2 | |
1188 | || (fallthru1 != 0) != (fallthru2 != 0)) | |
0dd0e980 JH |
1189 | return false; |
1190 | ||
1191 | /* fallthru edges must be forwarded to the same destination. */ | |
1192 | if (fallthru1) | |
1193 | { | |
1194 | basic_block d1 = (forwarder_block_p (fallthru1->dest) | |
1195 | ? fallthru1->dest->succ->dest: fallthru1->dest); | |
1196 | basic_block d2 = (forwarder_block_p (fallthru2->dest) | |
1197 | ? fallthru2->dest->succ->dest: fallthru2->dest); | |
5f0d2358 | 1198 | |
0dd0e980 JH |
1199 | if (d1 != d2) |
1200 | return false; | |
1201 | } | |
5f0d2358 | 1202 | |
0dd0e980 JH |
1203 | /* In case we do have EH edges, ensure we are in the same region. */ |
1204 | if (nehedges1) | |
1205 | { | |
1206 | rtx n1 = find_reg_note (bb1->end, REG_EH_REGION, 0); | |
1207 | rtx n2 = find_reg_note (bb2->end, REG_EH_REGION, 0); | |
5f0d2358 | 1208 | |
0dd0e980 JH |
1209 | if (XEXP (n1, 0) != XEXP (n2, 0)) |
1210 | return false; | |
1211 | } | |
5f0d2358 | 1212 | |
0dd0e980 JH |
1213 | /* We don't need to match the rest of edges as above checks should be enought |
1214 | to ensure that they are equivalent. */ | |
1215 | return true; | |
402209ff JH |
1216 | } |
1217 | ||
1218 | /* E1 and E2 are edges with the same destination block. Search their | |
1219 | predecessors for common code. If found, redirect control flow from | |
1220 | (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC. */ | |
1221 | ||
1222 | static bool | |
1223 | try_crossjump_to_edge (mode, e1, e2) | |
1224 | int mode; | |
1225 | edge e1, e2; | |
1226 | { | |
1227 | int nmatch; | |
1228 | basic_block src1 = e1->src, src2 = e2->src; | |
1229 | basic_block redirect_to; | |
1230 | rtx newpos1, newpos2; | |
1231 | edge s; | |
1232 | rtx last; | |
1233 | rtx label; | |
1234 | rtx note; | |
1235 | ||
1236 | /* Search backward through forwarder blocks. We don't need to worry | |
1237 | about multiple entry or chained forwarders, as they will be optimized | |
1238 | away. We do this to look past the unconditional jump following a | |
1239 | conditional jump that is required due to the current CFG shape. */ | |
1240 | if (src1->pred | |
1241 | && !src1->pred->pred_next | |
635559ab | 1242 | && FORWARDER_BLOCK_P (src1)) |
5f0d2358 RK |
1243 | e1 = src1->pred, src1 = e1->src; |
1244 | ||
402209ff JH |
1245 | if (src2->pred |
1246 | && !src2->pred->pred_next | |
635559ab | 1247 | && FORWARDER_BLOCK_P (src2)) |
5f0d2358 | 1248 | e2 = src2->pred, src2 = e2->src; |
402209ff JH |
1249 | |
1250 | /* Nothing to do if we reach ENTRY, or a common source block. */ | |
1251 | if (src1 == ENTRY_BLOCK_PTR || src2 == ENTRY_BLOCK_PTR) | |
1252 | return false; | |
1253 | if (src1 == src2) | |
1254 | return false; | |
1255 | ||
1256 | /* Seeing more than 1 forwarder blocks would confuse us later... */ | |
635559ab JH |
1257 | if (FORWARDER_BLOCK_P (e1->dest) |
1258 | && FORWARDER_BLOCK_P (e1->dest->succ->dest)) | |
402209ff | 1259 | return false; |
5f0d2358 | 1260 | |
635559ab JH |
1261 | if (FORWARDER_BLOCK_P (e2->dest) |
1262 | && FORWARDER_BLOCK_P (e2->dest->succ->dest)) | |
402209ff JH |
1263 | return false; |
1264 | ||
1265 | /* Likewise with dead code (possibly newly created by the other optimizations | |
1266 | of cfg_cleanup). */ | |
1267 | if (!src1->pred || !src2->pred) | |
1268 | return false; | |
1269 | ||
402209ff | 1270 | /* Look for the common insn sequence, part the first ... */ |
0dd0e980 | 1271 | if (!outgoing_edges_match (mode, src1, src2)) |
402209ff JH |
1272 | return false; |
1273 | ||
1274 | /* ... and part the second. */ | |
1275 | nmatch = flow_find_cross_jump (mode, src1, src2, &newpos1, &newpos2); | |
1276 | if (!nmatch) | |
1277 | return false; | |
1278 | ||
1279 | /* Avoid splitting if possible. */ | |
1280 | if (newpos2 == src2->head) | |
1281 | redirect_to = src2; | |
1282 | else | |
1283 | { | |
1284 | if (rtl_dump_file) | |
1285 | fprintf (rtl_dump_file, "Splitting bb %i before %i insns\n", | |
1286 | src2->index, nmatch); | |
1287 | redirect_to = split_block (src2, PREV_INSN (newpos2))->dest; | |
1288 | } | |
1289 | ||
1290 | if (rtl_dump_file) | |
1291 | fprintf (rtl_dump_file, | |
1292 | "Cross jumping from bb %i to bb %i; %i common insns\n", | |
1293 | src1->index, src2->index, nmatch); | |
1294 | ||
1295 | redirect_to->count += src1->count; | |
1296 | redirect_to->frequency += src1->frequency; | |
1297 | ||
1298 | /* Recompute the frequencies and counts of outgoing edges. */ | |
1299 | for (s = redirect_to->succ; s; s = s->succ_next) | |
1300 | { | |
1301 | edge s2; | |
1302 | basic_block d = s->dest; | |
1303 | ||
635559ab | 1304 | if (FORWARDER_BLOCK_P (d)) |
402209ff | 1305 | d = d->succ->dest; |
5f0d2358 | 1306 | |
402209ff JH |
1307 | for (s2 = src1->succ; ; s2 = s2->succ_next) |
1308 | { | |
1309 | basic_block d2 = s2->dest; | |
635559ab | 1310 | if (FORWARDER_BLOCK_P (d2)) |
402209ff JH |
1311 | d2 = d2->succ->dest; |
1312 | if (d == d2) | |
1313 | break; | |
1314 | } | |
5f0d2358 | 1315 | |
402209ff JH |
1316 | s->count += s2->count; |
1317 | ||
1318 | /* Take care to update possible forwarder blocks. We verified | |
1319 | that there is no more than one in the chain, so we can't run | |
1320 | into infinite loop. */ | |
635559ab | 1321 | if (FORWARDER_BLOCK_P (s->dest)) |
402209ff JH |
1322 | { |
1323 | s->dest->succ->count += s2->count; | |
1324 | s->dest->count += s2->count; | |
1325 | s->dest->frequency += EDGE_FREQUENCY (s); | |
1326 | } | |
5f0d2358 | 1327 | |
635559ab | 1328 | if (FORWARDER_BLOCK_P (s2->dest)) |
402209ff JH |
1329 | { |
1330 | s2->dest->succ->count -= s2->count; | |
1331 | s2->dest->count -= s2->count; | |
1332 | s2->dest->frequency -= EDGE_FREQUENCY (s); | |
1333 | } | |
5f0d2358 | 1334 | |
402209ff JH |
1335 | if (!redirect_to->frequency && !src1->frequency) |
1336 | s->probability = (s->probability + s2->probability) / 2; | |
1337 | else | |
5f0d2358 RK |
1338 | s->probability |
1339 | = ((s->probability * redirect_to->frequency + | |
1340 | s2->probability * src1->frequency) | |
1341 | / (redirect_to->frequency + src1->frequency)); | |
402209ff JH |
1342 | } |
1343 | ||
1344 | note = find_reg_note (redirect_to->end, REG_BR_PROB, 0); | |
1345 | if (note) | |
1346 | XEXP (note, 0) = GEN_INT (BRANCH_EDGE (redirect_to)->probability); | |
1347 | ||
1348 | /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */ | |
1349 | ||
1350 | /* Skip possible basic block header. */ | |
1351 | if (GET_CODE (newpos1) == CODE_LABEL) | |
1352 | newpos1 = NEXT_INSN (newpos1); | |
5f0d2358 | 1353 | |
402209ff JH |
1354 | if (GET_CODE (newpos1) == NOTE) |
1355 | newpos1 = NEXT_INSN (newpos1); | |
1356 | last = src1->end; | |
1357 | ||
6d2f8887 | 1358 | /* Emit the jump insn. */ |
402209ff | 1359 | label = block_label (redirect_to); |
53c17031 | 1360 | emit_jump_insn_after (gen_jump (label), src1->end); |
402209ff JH |
1361 | JUMP_LABEL (src1->end) = label; |
1362 | LABEL_NUSES (label)++; | |
402209ff JH |
1363 | |
1364 | /* Delete the now unreachable instructions. */ | |
53c17031 | 1365 | delete_insn_chain (newpos1, last); |
402209ff JH |
1366 | |
1367 | /* Make sure there is a barrier after the new jump. */ | |
1368 | last = next_nonnote_insn (src1->end); | |
1369 | if (!last || GET_CODE (last) != BARRIER) | |
1370 | emit_barrier_after (src1->end); | |
1371 | ||
1372 | /* Update CFG. */ | |
1373 | while (src1->succ) | |
1374 | remove_edge (src1->succ); | |
7ded4467 | 1375 | make_single_succ_edge (src1, redirect_to, 0); |
402209ff | 1376 | |
635559ab JH |
1377 | BB_SET_FLAG (src1, BB_UPDATE_LIFE); |
1378 | update_forwarder_flag (src1); | |
1379 | ||
402209ff JH |
1380 | return true; |
1381 | } | |
1382 | ||
1383 | /* Search the predecessors of BB for common insn sequences. When found, | |
1384 | share code between them by redirecting control flow. Return true if | |
1385 | any changes made. */ | |
1386 | ||
1387 | static bool | |
1388 | try_crossjump_bb (mode, bb) | |
1389 | int mode; | |
1390 | basic_block bb; | |
1391 | { | |
1392 | edge e, e2, nexte2, nexte, fallthru; | |
1393 | bool changed; | |
1394 | ||
f63d1bf7 | 1395 | /* Nothing to do if there is not at least two incoming edges. */ |
402209ff JH |
1396 | if (!bb->pred || !bb->pred->pred_next) |
1397 | return false; | |
1398 | ||
1399 | /* It is always cheapest to redirect a block that ends in a branch to | |
1400 | a block that falls through into BB, as that adds no branches to the | |
1401 | program. We'll try that combination first. */ | |
1402 | for (fallthru = bb->pred; fallthru; fallthru = fallthru->pred_next) | |
1403 | if (fallthru->flags & EDGE_FALLTHRU) | |
1404 | break; | |
1405 | ||
1406 | changed = false; | |
1407 | for (e = bb->pred; e; e = nexte) | |
1408 | { | |
1409 | nexte = e->pred_next; | |
1410 | ||
402209ff JH |
1411 | /* As noted above, first try with the fallthru predecessor. */ |
1412 | if (fallthru) | |
1413 | { | |
1414 | /* Don't combine the fallthru edge into anything else. | |
1415 | If there is a match, we'll do it the other way around. */ | |
1416 | if (e == fallthru) | |
1417 | continue; | |
1418 | ||
1419 | if (try_crossjump_to_edge (mode, e, fallthru)) | |
1420 | { | |
1421 | changed = true; | |
1422 | nexte = bb->pred; | |
1423 | continue; | |
1424 | } | |
1425 | } | |
1426 | ||
1427 | /* Non-obvious work limiting check: Recognize that we're going | |
1428 | to call try_crossjump_bb on every basic block. So if we have | |
1429 | two blocks with lots of outgoing edges (a switch) and they | |
1430 | share lots of common destinations, then we would do the | |
1431 | cross-jump check once for each common destination. | |
1432 | ||
1433 | Now, if the blocks actually are cross-jump candidates, then | |
1434 | all of their destinations will be shared. Which means that | |
1435 | we only need check them for cross-jump candidacy once. We | |
1436 | can eliminate redundant checks of crossjump(A,B) by arbitrarily | |
1437 | choosing to do the check from the block for which the edge | |
1438 | in question is the first successor of A. */ | |
1439 | if (e->src->succ != e) | |
1440 | continue; | |
1441 | ||
1442 | for (e2 = bb->pred; e2; e2 = nexte2) | |
1443 | { | |
1444 | nexte2 = e2->pred_next; | |
1445 | ||
1446 | if (e2 == e) | |
1447 | continue; | |
1448 | ||
1449 | /* We've already checked the fallthru edge above. */ | |
1450 | if (e2 == fallthru) | |
1451 | continue; | |
1452 | ||
402209ff JH |
1453 | /* The "first successor" check above only prevents multiple |
1454 | checks of crossjump(A,B). In order to prevent redundant | |
1455 | checks of crossjump(B,A), require that A be the block | |
1456 | with the lowest index. */ | |
1457 | if (e->src->index > e2->src->index) | |
1458 | continue; | |
1459 | ||
1460 | if (try_crossjump_to_edge (mode, e, e2)) | |
1461 | { | |
1462 | changed = true; | |
1463 | nexte = bb->pred; | |
1464 | break; | |
1465 | } | |
1466 | } | |
1467 | } | |
1468 | ||
1469 | return changed; | |
1470 | } | |
1471 | ||
1472 | /* Do simple CFG optimizations - basic block merging, simplifying of jump | |
1473 | instructions etc. Return nonzero if changes were made. */ | |
1474 | ||
1475 | static bool | |
1476 | try_optimize_cfg (mode) | |
1477 | int mode; | |
1478 | { | |
1479 | int i; | |
1480 | bool changed_overall = false; | |
1481 | bool changed; | |
1482 | int iterations = 0; | |
635559ab | 1483 | sbitmap blocks; |
402209ff | 1484 | |
ca6c03ca JH |
1485 | if (mode & CLEANUP_CROSSJUMP) |
1486 | add_noreturn_fake_exit_edges (); | |
1487 | ||
635559ab JH |
1488 | for (i = 0; i < n_basic_blocks; i++) |
1489 | update_forwarder_flag (BASIC_BLOCK (i)); | |
1490 | ||
402209ff JH |
1491 | /* Attempt to merge blocks as made possible by edge removal. If a block |
1492 | has only one successor, and the successor has only one predecessor, | |
1493 | they may be combined. */ | |
402209ff JH |
1494 | do |
1495 | { | |
1496 | changed = false; | |
1497 | iterations++; | |
1498 | ||
1499 | if (rtl_dump_file) | |
1500 | fprintf (rtl_dump_file, "\n\ntry_optimize_cfg iteration %i\n\n", | |
1501 | iterations); | |
1502 | ||
1503 | for (i = 0; i < n_basic_blocks;) | |
1504 | { | |
1505 | basic_block c, b = BASIC_BLOCK (i); | |
1506 | edge s; | |
1507 | bool changed_here = false; | |
1508 | ||
1509 | /* Delete trivially dead basic blocks. */ | |
1510 | while (b->pred == NULL) | |
1511 | { | |
1512 | c = BASIC_BLOCK (b->index - 1); | |
1513 | if (rtl_dump_file) | |
1514 | fprintf (rtl_dump_file, "Deleting block %i.\n", b->index); | |
5f0d2358 | 1515 | |
402209ff JH |
1516 | flow_delete_block (b); |
1517 | changed = true; | |
1518 | b = c; | |
1519 | } | |
1520 | ||
1521 | /* Remove code labels no longer used. Don't do this before | |
1522 | CALL_PLACEHOLDER is removed, as some branches may be hidden | |
1523 | within. */ | |
1524 | if (b->pred->pred_next == NULL | |
1525 | && (b->pred->flags & EDGE_FALLTHRU) | |
1526 | && !(b->pred->flags & EDGE_COMPLEX) | |
1527 | && GET_CODE (b->head) == CODE_LABEL | |
1528 | && (!(mode & CLEANUP_PRE_SIBCALL) | |
1529 | || !tail_recursion_label_p (b->head)) | |
ec10f7c7 RH |
1530 | /* If the previous block ends with a branch to this block, |
1531 | we can't delete the label. Normally this is a condjump | |
1532 | that is yet to be simplified, but if CASE_DROPS_THRU, | |
1533 | this can be a tablejump with some element going to the | |
1534 | same place as the default (fallthru). */ | |
402209ff | 1535 | && (b->pred->src == ENTRY_BLOCK_PTR |
ec10f7c7 RH |
1536 | || GET_CODE (b->pred->src->end) != JUMP_INSN |
1537 | || ! label_is_jump_target_p (b->head, b->pred->src->end))) | |
402209ff JH |
1538 | { |
1539 | rtx label = b->head; | |
5f0d2358 | 1540 | |
402209ff | 1541 | b->head = NEXT_INSN (b->head); |
53c17031 | 1542 | delete_insn_chain (label, label); |
402209ff JH |
1543 | if (rtl_dump_file) |
1544 | fprintf (rtl_dump_file, "Deleted label in block %i.\n", | |
1545 | b->index); | |
1546 | } | |
1547 | ||
1548 | /* If we fall through an empty block, we can remove it. */ | |
1549 | if (b->pred->pred_next == NULL | |
1550 | && (b->pred->flags & EDGE_FALLTHRU) | |
1551 | && GET_CODE (b->head) != CODE_LABEL | |
635559ab | 1552 | && FORWARDER_BLOCK_P (b) |
402209ff JH |
1553 | /* Note that forwarder_block_p true ensures that there |
1554 | is a successor for this block. */ | |
1555 | && (b->succ->flags & EDGE_FALLTHRU) | |
1556 | && n_basic_blocks > 1) | |
1557 | { | |
1558 | if (rtl_dump_file) | |
1559 | fprintf (rtl_dump_file, "Deleting fallthru block %i.\n", | |
1560 | b->index); | |
5f0d2358 | 1561 | |
402209ff JH |
1562 | c = BASIC_BLOCK (b->index ? b->index - 1 : 1); |
1563 | redirect_edge_succ_nodup (b->pred, b->succ->dest); | |
1564 | flow_delete_block (b); | |
1565 | changed = true; | |
1566 | b = c; | |
1567 | } | |
1568 | ||
1569 | /* Merge blocks. Loop because chains of blocks might be | |
1570 | combineable. */ | |
1571 | while ((s = b->succ) != NULL | |
1572 | && s->succ_next == NULL | |
1573 | && !(s->flags & EDGE_COMPLEX) | |
1574 | && (c = s->dest) != EXIT_BLOCK_PTR | |
1575 | && c->pred->pred_next == NULL | |
1576 | /* If the jump insn has side effects, | |
1577 | we can't kill the edge. */ | |
1578 | && (GET_CODE (b->end) != JUMP_INSN | |
1579 | || onlyjump_p (b->end)) | |
1580 | && merge_blocks (s, b, c, mode)) | |
1581 | changed_here = true; | |
1582 | ||
1583 | /* Simplify branch over branch. */ | |
1584 | if ((mode & CLEANUP_EXPENSIVE) && try_simplify_condjump (b)) | |
feb265ab JJ |
1585 | { |
1586 | BB_SET_FLAG (b, BB_UPDATE_LIFE); | |
1587 | changed_here = true; | |
1588 | } | |
402209ff JH |
1589 | |
1590 | /* If B has a single outgoing edge, but uses a non-trivial jump | |
1591 | instruction without side-effects, we can either delete the | |
1592 | jump entirely, or replace it with a simple unconditional jump. | |
1593 | Use redirect_edge_and_branch to do the dirty work. */ | |
1594 | if (b->succ | |
1595 | && ! b->succ->succ_next | |
1596 | && b->succ->dest != EXIT_BLOCK_PTR | |
1597 | && onlyjump_p (b->end) | |
1598 | && redirect_edge_and_branch (b->succ, b->succ->dest)) | |
635559ab JH |
1599 | { |
1600 | BB_SET_FLAG (b, BB_UPDATE_LIFE); | |
1601 | update_forwarder_flag (b); | |
1602 | changed_here = true; | |
1603 | } | |
402209ff JH |
1604 | |
1605 | /* Simplify branch to branch. */ | |
1606 | if (try_forward_edges (mode, b)) | |
1607 | changed_here = true; | |
1608 | ||
1609 | /* Look for shared code between blocks. */ | |
1610 | if ((mode & CLEANUP_CROSSJUMP) | |
1611 | && try_crossjump_bb (mode, b)) | |
1612 | changed_here = true; | |
1613 | ||
1614 | /* Don't get confused by the index shift caused by deleting | |
1615 | blocks. */ | |
1616 | if (!changed_here) | |
1617 | i = b->index + 1; | |
1618 | else | |
1619 | changed = true; | |
1620 | } | |
1621 | ||
1622 | if ((mode & CLEANUP_CROSSJUMP) | |
1623 | && try_crossjump_bb (mode, EXIT_BLOCK_PTR)) | |
1624 | changed = true; | |
1625 | ||
1626 | #ifdef ENABLE_CHECKING | |
1627 | if (changed) | |
1628 | verify_flow_info (); | |
1629 | #endif | |
1630 | ||
1631 | changed_overall |= changed; | |
1632 | } | |
1633 | while (changed); | |
ca6c03ca JH |
1634 | |
1635 | if (mode & CLEANUP_CROSSJUMP) | |
1636 | remove_fake_edges (); | |
1637 | ||
feb265ab | 1638 | if ((mode & CLEANUP_UPDATE_LIFE) && changed_overall) |
635559ab JH |
1639 | { |
1640 | bool found = 0; | |
5f0d2358 | 1641 | |
635559ab | 1642 | blocks = sbitmap_alloc (n_basic_blocks); |
feb265ab | 1643 | sbitmap_zero (blocks); |
635559ab JH |
1644 | for (i = 0; i < n_basic_blocks; i++) |
1645 | if (BB_FLAGS (BASIC_BLOCK (i)) & BB_UPDATE_LIFE) | |
1646 | { | |
1647 | found = 1; | |
1648 | SET_BIT (blocks, i); | |
1649 | } | |
5f0d2358 | 1650 | |
635559ab JH |
1651 | if (found) |
1652 | update_life_info (blocks, UPDATE_LIFE_GLOBAL, | |
1653 | PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE | |
1654 | | PROP_KILL_DEAD_CODE); | |
1655 | sbitmap_free (blocks); | |
1656 | } | |
5f0d2358 | 1657 | |
635559ab JH |
1658 | for (i = 0; i < n_basic_blocks; i++) |
1659 | BASIC_BLOCK (i)->aux = NULL; | |
1660 | ||
402209ff JH |
1661 | return changed_overall; |
1662 | } | |
1663 | \f | |
6d2f8887 | 1664 | /* Delete all unreachable basic blocks. */ |
4262e623 | 1665 | |
402209ff JH |
1666 | static bool |
1667 | delete_unreachable_blocks () | |
1668 | { | |
1669 | int i; | |
1670 | bool changed = false; | |
1671 | ||
1672 | find_unreachable_blocks (); | |
1673 | ||
1674 | /* Delete all unreachable basic blocks. Count down so that we | |
1675 | don't interfere with the block renumbering that happens in | |
1676 | flow_delete_block. */ | |
1677 | ||
1678 | for (i = n_basic_blocks - 1; i >= 0; --i) | |
1679 | { | |
1680 | basic_block b = BASIC_BLOCK (i); | |
1681 | ||
1682 | if (!(b->flags & BB_REACHABLE)) | |
1683 | flow_delete_block (b), changed = true; | |
1684 | } | |
1685 | ||
1686 | if (changed) | |
1687 | tidy_fallthru_edges (); | |
1688 | return changed; | |
1689 | } | |
402209ff JH |
1690 | \f |
1691 | /* Tidy the CFG by deleting unreachable code and whatnot. */ | |
1692 | ||
1693 | bool | |
1694 | cleanup_cfg (mode) | |
1695 | int mode; | |
1696 | { | |
402209ff JH |
1697 | bool changed = false; |
1698 | ||
1699 | timevar_push (TV_CLEANUP_CFG); | |
1700 | changed = delete_unreachable_blocks (); | |
1701 | if (try_optimize_cfg (mode)) | |
1702 | delete_unreachable_blocks (), changed = true; | |
1703 | ||
402209ff JH |
1704 | /* Kill the data we won't maintain. */ |
1705 | free_EXPR_LIST_list (&label_value_list); | |
1706 | free_EXPR_LIST_list (&tail_recursion_label_list); | |
1707 | timevar_pop (TV_CLEANUP_CFG); | |
1708 | ||
402209ff JH |
1709 | return changed; |
1710 | } |