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65f34de5 | 1 | /* Control flow optimization code for GNU compiler. |
2 | Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, | |
8f8dcce4 | 3 | 1999, 2000, 2001, 2002 Free Software Foundation, Inc. |
65f34de5 | 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 | |
4a82352a | 27 | successor. Simplification of the branch instruction is performed by |
65f34de5 | 28 | underlying infrastructure so branch can be converted to simplejump or |
35a3065a | 29 | eliminated). |
65f34de5 | 30 | - Cross jumping (tail merging) |
31 | - Conditional jump-around-simplejump simplification | |
32 | - Basic block merging. */ | |
33 | ||
34 | #include "config.h" | |
35 | #include "system.h" | |
805e22b2 | 36 | #include "coretypes.h" |
37 | #include "tm.h" | |
65f34de5 | 38 | #include "rtl.h" |
39 | #include "hard-reg-set.h" | |
40 | #include "basic-block.h" | |
41 | #include "timevar.h" | |
42 | #include "output.h" | |
43 | #include "insn-config.h" | |
44 | #include "flags.h" | |
45 | #include "recog.h" | |
46 | #include "toplev.h" | |
8cd78fca | 47 | #include "cselib.h" |
20eee3f6 | 48 | #include "tm_p.h" |
e27e52e0 | 49 | #include "target.h" |
65f34de5 | 50 | |
1b52f600 | 51 | /* cleanup_cfg maintains following flags for each basic block. */ |
5cc577b6 | 52 | |
53 | enum bb_flags | |
54 | { | |
33dbe4d1 | 55 | /* Set if BB is the forwarder block to avoid too many |
56 | forwarder_block_p calls. */ | |
73e2b81c | 57 | BB_FORWARDER_BLOCK = 1, |
58 | BB_NONTHREADABLE_BLOCK = 2 | |
5cc577b6 | 59 | }; |
33dbe4d1 | 60 | |
5cc577b6 | 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)) | |
33dbe4d1 | 66 | |
5cc577b6 | 67 | #define FORWARDER_BLOCK_P(BB) (BB_FLAGS (BB) & BB_FORWARDER_BLOCK) |
33dbe4d1 | 68 | |
65f34de5 | 69 | static bool try_crossjump_to_edge PARAMS ((int, edge, edge)); |
70 | static bool try_crossjump_bb PARAMS ((int, basic_block)); | |
ba38e12b | 71 | static bool outgoing_edges_match PARAMS ((int, |
72 | basic_block, basic_block)); | |
65f34de5 | 73 | static int flow_find_cross_jump PARAMS ((int, basic_block, basic_block, |
74 | rtx *, rtx *)); | |
ba38e12b | 75 | static bool insns_match_p PARAMS ((int, rtx, rtx)); |
65f34de5 | 76 | |
460ee42f | 77 | static bool label_is_jump_target_p PARAMS ((rtx, rtx)); |
e76f35e8 | 78 | static bool tail_recursion_label_p PARAMS ((rtx)); |
79 | static void merge_blocks_move_predecessor_nojumps PARAMS ((basic_block, | |
65f34de5 | 80 | basic_block)); |
e76f35e8 | 81 | static void merge_blocks_move_successor_nojumps PARAMS ((basic_block, |
65f34de5 | 82 | basic_block)); |
e76f35e8 | 83 | static bool merge_blocks PARAMS ((edge,basic_block,basic_block, |
65f34de5 | 84 | int)); |
85 | static bool try_optimize_cfg PARAMS ((int)); | |
86 | static bool try_simplify_condjump PARAMS ((basic_block)); | |
87 | static bool try_forward_edges PARAMS ((int, basic_block)); | |
8cd78fca | 88 | static edge thread_jump PARAMS ((int, edge, basic_block)); |
89 | static bool mark_effect PARAMS ((rtx, bitmap)); | |
33dbe4d1 | 90 | static void notice_new_block PARAMS ((basic_block)); |
91 | static void update_forwarder_flag PARAMS ((basic_block)); | |
4ccdad8e | 92 | static int mentions_nonequal_regs PARAMS ((rtx *, void *)); |
33dbe4d1 | 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; | |
5cc577b6 | 102 | |
33dbe4d1 | 103 | if (forwarder_block_p (bb)) |
104 | BB_SET_FLAG (bb, BB_FORWARDER_BLOCK); | |
105 | } | |
106 | ||
107 | /* Recompute forwarder flag after block has been modified. */ | |
108 | ||
109 | static void | |
110 | update_forwarder_flag (bb) | |
111 | basic_block bb; | |
112 | { | |
113 | if (forwarder_block_p (bb)) | |
114 | BB_SET_FLAG (bb, BB_FORWARDER_BLOCK); | |
115 | else | |
116 | BB_CLEAR_FLAG (bb, BB_FORWARDER_BLOCK); | |
117 | } | |
65f34de5 | 118 | \f |
119 | /* Simplify a conditional jump around an unconditional jump. | |
120 | Return true if something changed. */ | |
121 | ||
122 | static bool | |
123 | try_simplify_condjump (cbranch_block) | |
124 | basic_block cbranch_block; | |
125 | { | |
126 | basic_block jump_block, jump_dest_block, cbranch_dest_block; | |
127 | edge cbranch_jump_edge, cbranch_fallthru_edge; | |
128 | rtx cbranch_insn; | |
129 | ||
130 | /* Verify that there are exactly two successors. */ | |
131 | if (!cbranch_block->succ | |
132 | || !cbranch_block->succ->succ_next | |
133 | || cbranch_block->succ->succ_next->succ_next) | |
134 | return false; | |
135 | ||
136 | /* Verify that we've got a normal conditional branch at the end | |
137 | of the block. */ | |
138 | cbranch_insn = cbranch_block->end; | |
139 | if (!any_condjump_p (cbranch_insn)) | |
140 | return false; | |
141 | ||
142 | cbranch_fallthru_edge = FALLTHRU_EDGE (cbranch_block); | |
143 | cbranch_jump_edge = BRANCH_EDGE (cbranch_block); | |
144 | ||
145 | /* The next block must not have multiple predecessors, must not | |
146 | be the last block in the function, and must contain just the | |
147 | unconditional jump. */ | |
148 | jump_block = cbranch_fallthru_edge->dest; | |
149 | if (jump_block->pred->pred_next | |
345ac34a | 150 | || jump_block->next_bb == EXIT_BLOCK_PTR |
33dbe4d1 | 151 | || !FORWARDER_BLOCK_P (jump_block)) |
65f34de5 | 152 | return false; |
153 | jump_dest_block = jump_block->succ->dest; | |
154 | ||
155 | /* The conditional branch must target the block after the | |
156 | unconditional branch. */ | |
157 | cbranch_dest_block = cbranch_jump_edge->dest; | |
158 | ||
159 | if (!can_fallthru (jump_block, cbranch_dest_block)) | |
160 | return false; | |
161 | ||
b36d64df | 162 | /* Invert the conditional branch. */ |
163 | if (!invert_jump (cbranch_insn, block_label (jump_dest_block), 0)) | |
164 | return false; | |
65f34de5 | 165 | |
166 | if (rtl_dump_file) | |
167 | fprintf (rtl_dump_file, "Simplifying condjump %i around jump %i\n", | |
168 | INSN_UID (cbranch_insn), INSN_UID (jump_block->end)); | |
169 | ||
170 | /* Success. Update the CFG to match. Note that after this point | |
171 | the edge variable names appear backwards; the redirection is done | |
172 | this way to preserve edge profile data. */ | |
173 | cbranch_jump_edge = redirect_edge_succ_nodup (cbranch_jump_edge, | |
174 | cbranch_dest_block); | |
175 | cbranch_fallthru_edge = redirect_edge_succ_nodup (cbranch_fallthru_edge, | |
176 | jump_dest_block); | |
177 | cbranch_jump_edge->flags |= EDGE_FALLTHRU; | |
178 | cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU; | |
f884e43f | 179 | update_br_prob_note (cbranch_block); |
65f34de5 | 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 | |
8cd78fca | 188 | /* Attempt to prove that operation is NOOP using CSElib or mark the effect |
189 | on register. Used by jump threading. */ | |
5cc577b6 | 190 | |
8cd78fca | 191 | static bool |
192 | mark_effect (exp, nonequal) | |
db34a109 | 193 | rtx exp; |
194 | regset nonequal; | |
8cd78fca | 195 | { |
20eee3f6 | 196 | int regno; |
197 | rtx dest; | |
8cd78fca | 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. */ | |
db34a109 | 202 | case CLOBBER: |
203 | if (REG_P (XEXP (exp, 0))) | |
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 | } | |
215 | return false; | |
5cc577b6 | 216 | |
db34a109 | 217 | case SET: |
218 | if (rtx_equal_for_cselib_p (SET_DEST (exp), SET_SRC (exp))) | |
8cd78fca | 219 | return false; |
db34a109 | 220 | dest = SET_DEST (exp); |
221 | if (dest == pc_rtx) | |
8cd78fca | 222 | return false; |
db34a109 | 223 | if (!REG_P (dest)) |
224 | return true; | |
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 | } | |
233 | return false; | |
234 | ||
235 | default: | |
236 | return false; | |
8cd78fca | 237 | } |
238 | } | |
4ccdad8e | 239 | |
240 | /* Return nonzero if X is an register set in regset DATA. | |
241 | Called via for_each_rtx. */ | |
242 | static int | |
243 | mentions_nonequal_regs (x, data) | |
244 | rtx *x; | |
245 | void *data; | |
246 | { | |
247 | regset nonequal = (regset) data; | |
248 | if (REG_P (*x)) | |
249 | { | |
250 | int regno; | |
251 | ||
252 | regno = REGNO (*x); | |
253 | if (REGNO_REG_SET_P (nonequal, regno)) | |
254 | return 1; | |
255 | if (regno < FIRST_PSEUDO_REGISTER) | |
256 | { | |
257 | int n = HARD_REGNO_NREGS (regno, GET_MODE (*x)); | |
258 | while (--n > 0) | |
259 | if (REGNO_REG_SET_P (nonequal, regno + n)) | |
260 | return 1; | |
261 | } | |
262 | } | |
263 | return 0; | |
264 | } | |
8cd78fca | 265 | /* Attempt to prove that the basic block B will have no side effects and |
266 | allways continues in the same edge if reached via E. Return the edge | |
267 | if exist, NULL otherwise. */ | |
268 | ||
269 | static edge | |
270 | thread_jump (mode, e, b) | |
271 | int mode; | |
272 | edge e; | |
273 | basic_block b; | |
274 | { | |
275 | rtx set1, set2, cond1, cond2, insn; | |
276 | enum rtx_code code1, code2, reversed_code2; | |
277 | bool reverse1 = false; | |
278 | int i; | |
279 | regset nonequal; | |
280 | bool failed = false; | |
281 | ||
73e2b81c | 282 | if (BB_FLAGS (b) & BB_NONTHREADABLE_BLOCK) |
283 | return NULL; | |
284 | ||
8cd78fca | 285 | /* At the moment, we do handle only conditional jumps, but later we may |
286 | want to extend this code to tablejumps and others. */ | |
287 | if (!e->src->succ->succ_next || e->src->succ->succ_next->succ_next) | |
288 | return NULL; | |
289 | if (!b->succ || !b->succ->succ_next || b->succ->succ_next->succ_next) | |
73e2b81c | 290 | { |
291 | BB_SET_FLAG (b, BB_NONTHREADABLE_BLOCK); | |
292 | return NULL; | |
293 | } | |
8cd78fca | 294 | |
295 | /* Second branch must end with onlyjump, as we will eliminate the jump. */ | |
73e2b81c | 296 | if (!any_condjump_p (e->src->end)) |
8cd78fca | 297 | return NULL; |
db34a109 | 298 | |
73e2b81c | 299 | if (!any_condjump_p (b->end) || !onlyjump_p (b->end)) |
300 | { | |
301 | BB_SET_FLAG (b, BB_NONTHREADABLE_BLOCK); | |
302 | return NULL; | |
303 | } | |
8cd78fca | 304 | |
305 | set1 = pc_set (e->src->end); | |
306 | set2 = pc_set (b->end); | |
307 | if (((e->flags & EDGE_FALLTHRU) != 0) | |
dd782271 | 308 | != (XEXP (SET_SRC (set1), 1) == pc_rtx)) |
8cd78fca | 309 | reverse1 = true; |
310 | ||
311 | cond1 = XEXP (SET_SRC (set1), 0); | |
312 | cond2 = XEXP (SET_SRC (set2), 0); | |
313 | if (reverse1) | |
dd782271 | 314 | code1 = reversed_comparison_code (cond1, e->src->end); |
8cd78fca | 315 | else |
316 | code1 = GET_CODE (cond1); | |
317 | ||
318 | code2 = GET_CODE (cond2); | |
319 | reversed_code2 = reversed_comparison_code (cond2, b->end); | |
320 | ||
321 | if (!comparison_dominates_p (code1, code2) | |
322 | && !comparison_dominates_p (code1, reversed_code2)) | |
323 | return NULL; | |
324 | ||
325 | /* Ensure that the comparison operators are equivalent. | |
326 | ??? This is far too pesimistic. We should allow swapped operands, | |
327 | different CCmodes, or for example comparisons for interval, that | |
328 | dominate even when operands are not equivalent. */ | |
329 | if (!rtx_equal_p (XEXP (cond1, 0), XEXP (cond2, 0)) | |
330 | || !rtx_equal_p (XEXP (cond1, 1), XEXP (cond2, 1))) | |
331 | return NULL; | |
332 | ||
333 | /* Short circuit cases where block B contains some side effects, as we can't | |
334 | safely bypass it. */ | |
335 | for (insn = NEXT_INSN (b->head); insn != NEXT_INSN (b->end); | |
336 | insn = NEXT_INSN (insn)) | |
337 | if (INSN_P (insn) && side_effects_p (PATTERN (insn))) | |
73e2b81c | 338 | { |
339 | BB_SET_FLAG (b, BB_NONTHREADABLE_BLOCK); | |
340 | return NULL; | |
341 | } | |
8cd78fca | 342 | |
343 | cselib_init (); | |
344 | ||
345 | /* First process all values computed in the source basic block. */ | |
346 | for (insn = NEXT_INSN (e->src->head); insn != NEXT_INSN (e->src->end); | |
347 | insn = NEXT_INSN (insn)) | |
348 | if (INSN_P (insn)) | |
349 | cselib_process_insn (insn); | |
350 | ||
351 | nonequal = BITMAP_XMALLOC(); | |
352 | CLEAR_REG_SET (nonequal); | |
5cc577b6 | 353 | |
8cd78fca | 354 | /* Now assume that we've continued by the edge E to B and continue |
355 | processing as if it were same basic block. | |
8cd78fca | 356 | Our goal is to prove that whole block is an NOOP. */ |
5cc577b6 | 357 | |
20eee3f6 | 358 | for (insn = NEXT_INSN (b->head); insn != NEXT_INSN (b->end) && !failed; |
8cd78fca | 359 | insn = NEXT_INSN (insn)) |
db34a109 | 360 | { |
361 | if (INSN_P (insn)) | |
362 | { | |
363 | rtx pat = PATTERN (insn); | |
364 | ||
365 | if (GET_CODE (pat) == PARALLEL) | |
366 | { | |
367 | for (i = 0; i < XVECLEN (pat, 0); i++) | |
368 | failed |= mark_effect (XVECEXP (pat, 0, i), nonequal); | |
369 | } | |
370 | else | |
371 | failed |= mark_effect (pat, nonequal); | |
372 | } | |
5cc577b6 | 373 | |
db34a109 | 374 | cselib_process_insn (insn); |
375 | } | |
8cd78fca | 376 | |
377 | /* Later we should clear nonequal of dead registers. So far we don't | |
378 | have life information in cfg_cleanup. */ | |
379 | if (failed) | |
73e2b81c | 380 | { |
381 | BB_SET_FLAG (b, BB_NONTHREADABLE_BLOCK); | |
382 | goto failed_exit; | |
383 | } | |
8cd78fca | 384 | |
4ccdad8e | 385 | /* cond2 must not mention any register that is not equal to the |
386 | former block. */ | |
387 | if (for_each_rtx (&cond2, mentions_nonequal_regs, nonequal)) | |
388 | goto failed_exit; | |
389 | ||
8cd78fca | 390 | /* In case liveness information is available, we need to prove equivalence |
391 | only of the live values. */ | |
392 | if (mode & CLEANUP_UPDATE_LIFE) | |
393 | AND_REG_SET (nonequal, b->global_live_at_end); | |
394 | ||
395 | EXECUTE_IF_SET_IN_REG_SET (nonequal, 0, i, goto failed_exit;); | |
396 | ||
397 | BITMAP_XFREE (nonequal); | |
398 | cselib_finish (); | |
399 | if ((comparison_dominates_p (code1, code2) != 0) | |
148444fb | 400 | != (XEXP (SET_SRC (set2), 1) == pc_rtx)) |
8cd78fca | 401 | return BRANCH_EDGE (b); |
402 | else | |
403 | return FALLTHRU_EDGE (b); | |
404 | ||
405 | failed_exit: | |
406 | BITMAP_XFREE (nonequal); | |
407 | cselib_finish (); | |
408 | return NULL; | |
409 | } | |
410 | \f | |
65f34de5 | 411 | /* Attempt to forward edges leaving basic block B. |
4a82352a | 412 | Return true if successful. */ |
65f34de5 | 413 | |
414 | static bool | |
415 | try_forward_edges (mode, b) | |
416 | basic_block b; | |
417 | int mode; | |
418 | { | |
419 | bool changed = false; | |
309306ce | 420 | edge e, next, *threaded_edges = NULL; |
65f34de5 | 421 | |
5cc577b6 | 422 | for (e = b->succ; e; e = next) |
65f34de5 | 423 | { |
424 | basic_block target, first; | |
425 | int counter; | |
8cd78fca | 426 | bool threaded = false; |
d2855ea6 | 427 | int nthreaded_edges = 0; |
65f34de5 | 428 | |
429 | next = e->succ_next; | |
430 | ||
431 | /* Skip complex edges because we don't know how to update them. | |
432 | ||
4a82352a | 433 | Still handle fallthru edges, as we can succeed to forward fallthru |
65f34de5 | 434 | edge to the same place as the branch edge of conditional branch |
4a82352a | 435 | and turn conditional branch to an unconditional branch. */ |
65f34de5 | 436 | if (e->flags & EDGE_COMPLEX) |
437 | continue; | |
438 | ||
439 | target = first = e->dest; | |
440 | counter = 0; | |
441 | ||
b3d6de89 | 442 | while (counter < n_basic_blocks) |
65f34de5 | 443 | { |
8cd78fca | 444 | basic_block new_target = NULL; |
445 | bool new_target_threaded = false; | |
446 | ||
447 | if (FORWARDER_BLOCK_P (target) | |
448 | && target->succ->dest != EXIT_BLOCK_PTR) | |
449 | { | |
450 | /* Bypass trivial infinite loops. */ | |
451 | if (target == target->succ->dest) | |
b3d6de89 | 452 | counter = n_basic_blocks; |
8cd78fca | 453 | new_target = target->succ->dest; |
454 | } | |
5cc577b6 | 455 | |
8cd78fca | 456 | /* Allow to thread only over one edge at time to simplify updating |
457 | of probabilities. */ | |
309306ce | 458 | else if (mode & CLEANUP_THREADING) |
8cd78fca | 459 | { |
309306ce | 460 | edge t = thread_jump (mode, e, target); |
461 | if (t) | |
8cd78fca | 462 | { |
d2855ea6 | 463 | if (!threaded_edges) |
309306ce | 464 | threaded_edges = xmalloc (sizeof (*threaded_edges) |
b3d6de89 | 465 | * n_basic_blocks); |
acf4e6a8 | 466 | else |
467 | { | |
468 | int i; | |
469 | ||
470 | /* Detect an infinite loop across blocks not | |
471 | including the start block. */ | |
472 | for (i = 0; i < nthreaded_edges; ++i) | |
473 | if (threaded_edges[i] == t) | |
474 | break; | |
475 | if (i < nthreaded_edges) | |
e9bc5a2d | 476 | { |
b3d6de89 | 477 | counter = n_basic_blocks; |
e9bc5a2d | 478 | break; |
479 | } | |
acf4e6a8 | 480 | } |
481 | ||
482 | /* Detect an infinite loop across the start block. */ | |
483 | if (t->dest == b) | |
484 | break; | |
485 | ||
b3d6de89 | 486 | if (nthreaded_edges >= n_basic_blocks) |
acf4e6a8 | 487 | abort (); |
309306ce | 488 | threaded_edges[nthreaded_edges++] = t; |
acf4e6a8 | 489 | |
490 | new_target = t->dest; | |
491 | new_target_threaded = true; | |
8cd78fca | 492 | } |
493 | } | |
5cc577b6 | 494 | |
8cd78fca | 495 | if (!new_target) |
496 | break; | |
65f34de5 | 497 | |
498 | /* Avoid killing of loop pre-headers, as it is the place loop | |
499 | optimizer wants to hoist code to. | |
500 | ||
501 | For fallthru forwarders, the LOOP_BEG note must appear between | |
502 | the header of block and CODE_LABEL of the loop, for non forwarders | |
503 | it must appear before the JUMP_INSN. */ | |
504 | if (mode & CLEANUP_PRE_LOOP) | |
505 | { | |
506 | rtx insn = (target->succ->flags & EDGE_FALLTHRU | |
db34a109 | 507 | ? target->head : prev_nonnote_insn (target->end)); |
65f34de5 | 508 | |
509 | if (GET_CODE (insn) != NOTE) | |
510 | insn = NEXT_INSN (insn); | |
511 | ||
5cc577b6 | 512 | for (; insn && GET_CODE (insn) != CODE_LABEL && !INSN_P (insn); |
65f34de5 | 513 | insn = NEXT_INSN (insn)) |
514 | if (GET_CODE (insn) == NOTE | |
515 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) | |
516 | break; | |
517 | ||
518 | if (GET_CODE (insn) == NOTE) | |
519 | break; | |
c21a402e | 520 | |
521 | /* Do not clean up branches to just past the end of a loop | |
522 | at this time; it can mess up the loop optimizer's | |
9cb8e99f | 523 | recognition of some patterns. */ |
c21a402e | 524 | |
525 | insn = PREV_INSN (target->head); | |
526 | if (insn && GET_CODE (insn) == NOTE | |
527 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END) | |
528 | break; | |
65f34de5 | 529 | } |
5cc577b6 | 530 | |
8cd78fca | 531 | counter++; |
532 | target = new_target; | |
533 | threaded |= new_target_threaded; | |
db34a109 | 534 | } |
65f34de5 | 535 | |
b3d6de89 | 536 | if (counter >= n_basic_blocks) |
65f34de5 | 537 | { |
538 | if (rtl_dump_file) | |
539 | fprintf (rtl_dump_file, "Infinite loop in BB %i.\n", | |
b3d6de89 | 540 | target->index); |
65f34de5 | 541 | } |
542 | else if (target == first) | |
543 | ; /* We didn't do anything. */ | |
544 | else | |
545 | { | |
546 | /* Save the values now, as the edge may get removed. */ | |
547 | gcov_type edge_count = e->count; | |
548 | int edge_probability = e->probability; | |
8cd78fca | 549 | int edge_frequency; |
309306ce | 550 | int n = 0; |
65f34de5 | 551 | |
8963581a | 552 | /* Don't force if target is exit block. */ |
553 | if (threaded && target != EXIT_BLOCK_PTR) | |
65f34de5 | 554 | { |
8cd78fca | 555 | notice_new_block (redirect_edge_and_branch_force (e, target)); |
556 | if (rtl_dump_file) | |
db34a109 | 557 | fprintf (rtl_dump_file, "Conditionals threaded.\n"); |
65f34de5 | 558 | } |
8cd78fca | 559 | else if (!redirect_edge_and_branch (e, target)) |
65f34de5 | 560 | { |
561 | if (rtl_dump_file) | |
5cc577b6 | 562 | fprintf (rtl_dump_file, |
563 | "Forwarding edge %i->%i to %i failed.\n", | |
b3d6de89 | 564 | b->index, e->dest->index, target->index); |
8cd78fca | 565 | continue; |
65f34de5 | 566 | } |
5cc577b6 | 567 | |
8cd78fca | 568 | /* We successfully forwarded the edge. Now update profile |
569 | data: for each edge we traversed in the chain, remove | |
570 | the original edge's execution count. */ | |
571 | edge_frequency = ((edge_probability * b->frequency | |
572 | + REG_BR_PROB_BASE / 2) | |
573 | / REG_BR_PROB_BASE); | |
574 | ||
575 | if (!FORWARDER_BLOCK_P (b) && forwarder_block_p (b)) | |
576 | BB_SET_FLAG (b, BB_FORWARDER_BLOCK); | |
8cd78fca | 577 | |
578 | do | |
579 | { | |
580 | edge t; | |
5cc577b6 | 581 | |
8cd78fca | 582 | first->count -= edge_count; |
f884e43f | 583 | if (first->count < 0) |
584 | first->count = 0; | |
8cd78fca | 585 | first->frequency -= edge_frequency; |
f884e43f | 586 | if (first->frequency < 0) |
587 | first->frequency = 0; | |
8cd78fca | 588 | if (first->succ->succ_next) |
acf4e6a8 | 589 | { |
d2855ea6 | 590 | edge e; |
591 | int prob; | |
acf4e6a8 | 592 | if (n >= nthreaded_edges) |
593 | abort (); | |
594 | t = threaded_edges [n++]; | |
d2855ea6 | 595 | if (t->src != first) |
596 | abort (); | |
597 | if (first->frequency) | |
598 | prob = edge_frequency * REG_BR_PROB_BASE / first->frequency; | |
599 | else | |
600 | prob = 0; | |
f884e43f | 601 | if (prob > t->probability) |
602 | prob = t->probability; | |
d2855ea6 | 603 | t->probability -= prob; |
604 | prob = REG_BR_PROB_BASE - prob; | |
f884e43f | 605 | if (prob <= 0) |
d2855ea6 | 606 | { |
607 | first->succ->probability = REG_BR_PROB_BASE; | |
608 | first->succ->succ_next->probability = 0; | |
609 | } | |
610 | else | |
611 | for (e = first->succ; e; e = e->succ_next) | |
612 | e->probability = ((e->probability * REG_BR_PROB_BASE) | |
613 | / (double) prob); | |
f884e43f | 614 | update_br_prob_note (first); |
acf4e6a8 | 615 | } |
8cd78fca | 616 | else |
d2855ea6 | 617 | { |
618 | /* It is possible that as the result of | |
619 | threading we've removed edge as it is | |
620 | threaded to the fallthru edge. Avoid | |
621 | getting out of sync. */ | |
622 | if (n < nthreaded_edges | |
623 | && first == threaded_edges [n]->src) | |
624 | n++; | |
625 | t = first->succ; | |
db34a109 | 626 | } |
5cc577b6 | 627 | |
f884e43f | 628 | t->count -= edge_count; |
629 | if (t->count < 0) | |
630 | t->count = 0; | |
8cd78fca | 631 | first = t->dest; |
632 | } | |
633 | while (first != target); | |
634 | ||
635 | changed = true; | |
65f34de5 | 636 | } |
637 | } | |
638 | ||
309306ce | 639 | if (threaded_edges) |
640 | free (threaded_edges); | |
65f34de5 | 641 | return changed; |
642 | } | |
643 | \f | |
460ee42f | 644 | /* Return true if LABEL is a target of JUMP_INSN. This applies only |
645 | to non-complex jumps. That is, direct unconditional, conditional, | |
646 | and tablejumps, but not computed jumps or returns. It also does | |
647 | not apply to the fallthru case of a conditional jump. */ | |
648 | ||
649 | static bool | |
650 | label_is_jump_target_p (label, jump_insn) | |
651 | rtx label, jump_insn; | |
652 | { | |
653 | rtx tmp = JUMP_LABEL (jump_insn); | |
654 | ||
655 | if (label == tmp) | |
656 | return true; | |
657 | ||
658 | if (tmp != NULL_RTX | |
659 | && (tmp = NEXT_INSN (tmp)) != NULL_RTX | |
660 | && GET_CODE (tmp) == JUMP_INSN | |
661 | && (tmp = PATTERN (tmp), | |
662 | GET_CODE (tmp) == ADDR_VEC | |
663 | || GET_CODE (tmp) == ADDR_DIFF_VEC)) | |
664 | { | |
665 | rtvec vec = XVEC (tmp, GET_CODE (tmp) == ADDR_DIFF_VEC); | |
666 | int i, veclen = GET_NUM_ELEM (vec); | |
667 | ||
668 | for (i = 0; i < veclen; ++i) | |
669 | if (XEXP (RTVEC_ELT (vec, i), 0) == label) | |
670 | return true; | |
671 | } | |
672 | ||
673 | return false; | |
674 | } | |
675 | ||
e76f35e8 | 676 | /* Return true if LABEL is used for tail recursion. */ |
677 | ||
678 | static bool | |
65f34de5 | 679 | tail_recursion_label_p (label) |
680 | rtx label; | |
681 | { | |
682 | rtx x; | |
683 | ||
684 | for (x = tail_recursion_label_list; x; x = XEXP (x, 1)) | |
685 | if (label == XEXP (x, 0)) | |
e76f35e8 | 686 | return true; |
65f34de5 | 687 | |
e76f35e8 | 688 | return false; |
65f34de5 | 689 | } |
690 | ||
691 | /* Blocks A and B are to be merged into a single block. A has no incoming | |
692 | fallthru edge, so it can be moved before B without adding or modifying | |
693 | any jumps (aside from the jump from A to B). */ | |
694 | ||
e76f35e8 | 695 | static void |
65f34de5 | 696 | merge_blocks_move_predecessor_nojumps (a, b) |
697 | basic_block a, b; | |
698 | { | |
699 | rtx barrier; | |
65f34de5 | 700 | |
701 | barrier = next_nonnote_insn (a->end); | |
702 | if (GET_CODE (barrier) != BARRIER) | |
703 | abort (); | |
e4bf866d | 704 | delete_insn (barrier); |
65f34de5 | 705 | |
706 | /* Move block and loop notes out of the chain so that we do not | |
707 | disturb their order. | |
708 | ||
709 | ??? A better solution would be to squeeze out all the non-nested notes | |
710 | and adjust the block trees appropriately. Even better would be to have | |
711 | a tighter connection between block trees and rtl so that this is not | |
712 | necessary. */ | |
87dc0300 | 713 | if (squeeze_notes (&a->head, &a->end)) |
714 | abort (); | |
65f34de5 | 715 | |
716 | /* Scramble the insn chain. */ | |
717 | if (a->end != PREV_INSN (b->head)) | |
9dda7915 | 718 | reorder_insns_nobb (a->head, a->end, PREV_INSN (b->head)); |
308f9b79 | 719 | a->flags |= BB_DIRTY; |
65f34de5 | 720 | |
721 | if (rtl_dump_file) | |
5cc577b6 | 722 | fprintf (rtl_dump_file, "Moved block %d before %d and merged.\n", |
b3d6de89 | 723 | a->index, b->index); |
65f34de5 | 724 | |
3c0a32c9 | 725 | /* Swap the records for the two blocks around. */ |
65f34de5 | 726 | |
7fa55aef | 727 | unlink_block (a); |
728 | link_block (a, b->prev_bb); | |
729 | ||
65f34de5 | 730 | /* Now blocks A and B are contiguous. Merge them. */ |
731 | merge_blocks_nomove (a, b); | |
65f34de5 | 732 | } |
733 | ||
734 | /* Blocks A and B are to be merged into a single block. B has no outgoing | |
735 | fallthru edge, so it can be moved after A without adding or modifying | |
736 | any jumps (aside from the jump from A to B). */ | |
737 | ||
e76f35e8 | 738 | static void |
65f34de5 | 739 | merge_blocks_move_successor_nojumps (a, b) |
740 | basic_block a, b; | |
741 | { | |
f70d6641 | 742 | rtx barrier, real_b_end; |
65f34de5 | 743 | |
f70d6641 | 744 | real_b_end = b->end; |
65f34de5 | 745 | barrier = NEXT_INSN (b->end); |
746 | ||
747 | /* Recognize a jump table following block B. */ | |
748 | if (barrier | |
749 | && GET_CODE (barrier) == CODE_LABEL | |
750 | && NEXT_INSN (barrier) | |
751 | && GET_CODE (NEXT_INSN (barrier)) == JUMP_INSN | |
752 | && (GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_VEC | |
753 | || GET_CODE (PATTERN (NEXT_INSN (barrier))) == ADDR_DIFF_VEC)) | |
754 | { | |
f70d6641 | 755 | /* Temporarily add the table jump insn to b, so that it will also |
756 | be moved to the correct location. */ | |
65f34de5 | 757 | b->end = NEXT_INSN (barrier); |
758 | barrier = NEXT_INSN (b->end); | |
759 | } | |
760 | ||
761 | /* There had better have been a barrier there. Delete it. */ | |
762 | if (barrier && GET_CODE (barrier) == BARRIER) | |
e4bf866d | 763 | delete_insn (barrier); |
65f34de5 | 764 | |
765 | /* Move block and loop notes out of the chain so that we do not | |
766 | disturb their order. | |
767 | ||
768 | ??? A better solution would be to squeeze out all the non-nested notes | |
769 | and adjust the block trees appropriately. Even better would be to have | |
770 | a tighter connection between block trees and rtl so that this is not | |
771 | necessary. */ | |
87dc0300 | 772 | if (squeeze_notes (&b->head, &b->end)) |
773 | abort (); | |
65f34de5 | 774 | |
775 | /* Scramble the insn chain. */ | |
9dda7915 | 776 | reorder_insns_nobb (b->head, b->end, a->end); |
65f34de5 | 777 | |
f70d6641 | 778 | /* Restore the real end of b. */ |
779 | b->end = real_b_end; | |
780 | ||
65f34de5 | 781 | if (rtl_dump_file) |
5cc577b6 | 782 | fprintf (rtl_dump_file, "Moved block %d after %d and merged.\n", |
b3d6de89 | 783 | b->index, a->index); |
cd2e6f57 | 784 | |
785 | /* Now blocks A and B are contiguous. Merge them. */ | |
786 | merge_blocks_nomove (a, b); | |
65f34de5 | 787 | } |
788 | ||
789 | /* Attempt to merge basic blocks that are potentially non-adjacent. | |
790 | Return true iff the attempt succeeded. */ | |
791 | ||
e76f35e8 | 792 | static bool |
65f34de5 | 793 | merge_blocks (e, b, c, mode) |
794 | edge e; | |
795 | basic_block b, c; | |
796 | int mode; | |
797 | { | |
798 | /* If C has a tail recursion label, do not merge. There is no | |
799 | edge recorded from the call_placeholder back to this label, as | |
800 | that would make optimize_sibling_and_tail_recursive_calls more | |
801 | complex for no gain. */ | |
e76f35e8 | 802 | if ((mode & CLEANUP_PRE_SIBCALL) |
803 | && GET_CODE (c->head) == CODE_LABEL | |
65f34de5 | 804 | && tail_recursion_label_p (c->head)) |
e76f35e8 | 805 | return false; |
65f34de5 | 806 | |
807 | /* If B has a fallthru edge to C, no need to move anything. */ | |
808 | if (e->flags & EDGE_FALLTHRU) | |
809 | { | |
b3d6de89 | 810 | int b_index = b->index, c_index = c->index; |
65f34de5 | 811 | merge_blocks_nomove (b, c); |
33dbe4d1 | 812 | update_forwarder_flag (b); |
65f34de5 | 813 | |
814 | if (rtl_dump_file) | |
5cc577b6 | 815 | fprintf (rtl_dump_file, "Merged %d and %d without moving.\n", |
db34a109 | 816 | b_index, c_index); |
65f34de5 | 817 | |
e76f35e8 | 818 | return true; |
65f34de5 | 819 | } |
5cc577b6 | 820 | |
65f34de5 | 821 | /* Otherwise we will need to move code around. Do that only if expensive |
822 | transformations are allowed. */ | |
823 | else if (mode & CLEANUP_EXPENSIVE) | |
824 | { | |
e76f35e8 | 825 | edge tmp_edge, b_fallthru_edge; |
826 | bool c_has_outgoing_fallthru; | |
827 | bool b_has_incoming_fallthru; | |
65f34de5 | 828 | |
829 | /* Avoid overactive code motion, as the forwarder blocks should be | |
830 | eliminated by edge redirection instead. One exception might have | |
831 | been if B is a forwarder block and C has no fallthru edge, but | |
832 | that should be cleaned up by bb-reorder instead. */ | |
33dbe4d1 | 833 | if (FORWARDER_BLOCK_P (b) || FORWARDER_BLOCK_P (c)) |
e76f35e8 | 834 | return false; |
65f34de5 | 835 | |
836 | /* We must make sure to not munge nesting of lexical blocks, | |
837 | and loop notes. This is done by squeezing out all the notes | |
838 | and leaving them there to lie. Not ideal, but functional. */ | |
839 | ||
840 | for (tmp_edge = c->succ; tmp_edge; tmp_edge = tmp_edge->succ_next) | |
841 | if (tmp_edge->flags & EDGE_FALLTHRU) | |
842 | break; | |
5cc577b6 | 843 | |
65f34de5 | 844 | c_has_outgoing_fallthru = (tmp_edge != NULL); |
65f34de5 | 845 | |
846 | for (tmp_edge = b->pred; tmp_edge; tmp_edge = tmp_edge->pred_next) | |
847 | if (tmp_edge->flags & EDGE_FALLTHRU) | |
848 | break; | |
5cc577b6 | 849 | |
65f34de5 | 850 | b_has_incoming_fallthru = (tmp_edge != NULL); |
e76f35e8 | 851 | b_fallthru_edge = tmp_edge; |
852 | ||
853 | /* Otherwise, we're going to try to move C after B. If C does | |
854 | not have an outgoing fallthru, then it can be moved | |
855 | immediately after B without introducing or modifying jumps. */ | |
856 | if (! c_has_outgoing_fallthru) | |
857 | { | |
858 | merge_blocks_move_successor_nojumps (b, c); | |
859 | return true; | |
860 | } | |
65f34de5 | 861 | |
862 | /* If B does not have an incoming fallthru, then it can be moved | |
863 | immediately before C without introducing or modifying jumps. | |
864 | C cannot be the first block, so we do not have to worry about | |
865 | accessing a non-existent block. */ | |
65f34de5 | 866 | |
e76f35e8 | 867 | if (b_has_incoming_fallthru) |
868 | { | |
0922c912 | 869 | basic_block bb; |
5cc577b6 | 870 | |
e76f35e8 | 871 | if (b_fallthru_edge->src == ENTRY_BLOCK_PTR) |
872 | return false; | |
2a22a8e6 | 873 | bb = force_nonfallthru (b_fallthru_edge); |
874 | if (bb) | |
875 | notice_new_block (bb); | |
e76f35e8 | 876 | } |
5cc577b6 | 877 | |
e76f35e8 | 878 | merge_blocks_move_predecessor_nojumps (b, c); |
879 | return true; | |
65f34de5 | 880 | } |
5cc577b6 | 881 | |
e76f35e8 | 882 | return false; |
65f34de5 | 883 | } |
884 | \f | |
ba38e12b | 885 | |
886 | /* Return true if I1 and I2 are equivalent and thus can be crossjumped. */ | |
887 | ||
888 | static bool | |
889 | insns_match_p (mode, i1, i2) | |
db34a109 | 890 | int mode ATTRIBUTE_UNUSED; |
891 | rtx i1, i2; | |
ba38e12b | 892 | { |
893 | rtx p1, p2; | |
894 | ||
895 | /* Verify that I1 and I2 are equivalent. */ | |
896 | if (GET_CODE (i1) != GET_CODE (i2)) | |
897 | return false; | |
898 | ||
899 | p1 = PATTERN (i1); | |
900 | p2 = PATTERN (i2); | |
901 | ||
902 | if (GET_CODE (p1) != GET_CODE (p2)) | |
903 | return false; | |
904 | ||
905 | /* If this is a CALL_INSN, compare register usage information. | |
906 | If we don't check this on stack register machines, the two | |
907 | CALL_INSNs might be merged leaving reg-stack.c with mismatching | |
908 | numbers of stack registers in the same basic block. | |
909 | If we don't check this on machines with delay slots, a delay slot may | |
910 | be filled that clobbers a parameter expected by the subroutine. | |
911 | ||
912 | ??? We take the simple route for now and assume that if they're | |
913 | equal, they were constructed identically. */ | |
914 | ||
915 | if (GET_CODE (i1) == CALL_INSN | |
0d86b7af | 916 | && (!rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1), |
917 | CALL_INSN_FUNCTION_USAGE (i2)) | |
918 | || SIBLING_CALL_P (i1) != SIBLING_CALL_P (i2))) | |
ba38e12b | 919 | return false; |
920 | ||
921 | #ifdef STACK_REGS | |
922 | /* If cross_jump_death_matters is not 0, the insn's mode | |
923 | indicates whether or not the insn contains any stack-like | |
924 | regs. */ | |
925 | ||
926 | if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1)) | |
927 | { | |
928 | /* If register stack conversion has already been done, then | |
929 | death notes must also be compared before it is certain that | |
930 | the two instruction streams match. */ | |
931 | ||
932 | rtx note; | |
933 | HARD_REG_SET i1_regset, i2_regset; | |
934 | ||
935 | CLEAR_HARD_REG_SET (i1_regset); | |
936 | CLEAR_HARD_REG_SET (i2_regset); | |
937 | ||
938 | for (note = REG_NOTES (i1); note; note = XEXP (note, 1)) | |
939 | if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) | |
940 | SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0))); | |
941 | ||
942 | for (note = REG_NOTES (i2); note; note = XEXP (note, 1)) | |
943 | if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0))) | |
944 | SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0))); | |
945 | ||
946 | GO_IF_HARD_REG_EQUAL (i1_regset, i2_regset, done); | |
947 | ||
948 | return false; | |
949 | ||
950 | done: | |
951 | ; | |
952 | } | |
953 | #endif | |
954 | ||
955 | if (reload_completed | |
956 | ? ! rtx_renumbered_equal_p (p1, p2) : ! rtx_equal_p (p1, p2)) | |
957 | { | |
958 | /* The following code helps take care of G++ cleanups. */ | |
959 | rtx equiv1 = find_reg_equal_equiv_note (i1); | |
960 | rtx equiv2 = find_reg_equal_equiv_note (i2); | |
961 | ||
962 | if (equiv1 && equiv2 | |
963 | /* If the equivalences are not to a constant, they may | |
964 | reference pseudos that no longer exist, so we can't | |
965 | use them. */ | |
966 | && (! reload_completed | |
967 | || (CONSTANT_P (XEXP (equiv1, 0)) | |
968 | && rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0))))) | |
969 | { | |
970 | rtx s1 = single_set (i1); | |
971 | rtx s2 = single_set (i2); | |
972 | if (s1 != 0 && s2 != 0 | |
973 | && rtx_renumbered_equal_p (SET_DEST (s1), SET_DEST (s2))) | |
974 | { | |
975 | validate_change (i1, &SET_SRC (s1), XEXP (equiv1, 0), 1); | |
976 | validate_change (i2, &SET_SRC (s2), XEXP (equiv2, 0), 1); | |
977 | if (! rtx_renumbered_equal_p (p1, p2)) | |
978 | cancel_changes (0); | |
979 | else if (apply_change_group ()) | |
980 | return true; | |
981 | } | |
982 | } | |
5cc577b6 | 983 | |
ba38e12b | 984 | return false; |
985 | } | |
5cc577b6 | 986 | |
ba38e12b | 987 | return true; |
988 | } | |
989 | \f | |
65f34de5 | 990 | /* Look through the insns at the end of BB1 and BB2 and find the longest |
991 | sequence that are equivalent. Store the first insns for that sequence | |
992 | in *F1 and *F2 and return the sequence length. | |
993 | ||
994 | To simplify callers of this function, if the blocks match exactly, | |
995 | store the head of the blocks in *F1 and *F2. */ | |
996 | ||
997 | static int | |
998 | flow_find_cross_jump (mode, bb1, bb2, f1, f2) | |
999 | int mode ATTRIBUTE_UNUSED; | |
1000 | basic_block bb1, bb2; | |
1001 | rtx *f1, *f2; | |
1002 | { | |
ba38e12b | 1003 | rtx i1, i2, last1, last2, afterlast1, afterlast2; |
65f34de5 | 1004 | int ninsns = 0; |
1005 | ||
1006 | /* Skip simple jumps at the end of the blocks. Complex jumps still | |
1007 | need to be compared for equivalence, which we'll do below. */ | |
1008 | ||
1009 | i1 = bb1->end; | |
a716a89b | 1010 | last1 = afterlast1 = last2 = afterlast2 = NULL_RTX; |
65f34de5 | 1011 | if (onlyjump_p (i1) |
1012 | || (returnjump_p (i1) && !side_effects_p (PATTERN (i1)))) | |
a716a89b | 1013 | { |
1014 | last1 = i1; | |
a716a89b | 1015 | i1 = PREV_INSN (i1); |
1016 | } | |
5cc577b6 | 1017 | |
65f34de5 | 1018 | i2 = bb2->end; |
1019 | if (onlyjump_p (i2) | |
1020 | || (returnjump_p (i2) && !side_effects_p (PATTERN (i2)))) | |
a716a89b | 1021 | { |
1022 | last2 = i2; | |
3bf090f7 | 1023 | /* Count everything except for unconditional jump as insn. */ |
1024 | if (!simplejump_p (i2) && !returnjump_p (i2) && last1) | |
1025 | ninsns++; | |
a716a89b | 1026 | i2 = PREV_INSN (i2); |
1027 | } | |
65f34de5 | 1028 | |
65f34de5 | 1029 | while (true) |
1030 | { | |
1031 | /* Ignore notes. */ | |
a716a89b | 1032 | while (!active_insn_p (i1) && i1 != bb1->head) |
65f34de5 | 1033 | i1 = PREV_INSN (i1); |
5cc577b6 | 1034 | |
a716a89b | 1035 | while (!active_insn_p (i2) && i2 != bb2->head) |
65f34de5 | 1036 | i2 = PREV_INSN (i2); |
1037 | ||
1038 | if (i1 == bb1->head || i2 == bb2->head) | |
1039 | break; | |
1040 | ||
ba38e12b | 1041 | if (!insns_match_p (mode, i1, i2)) |
65f34de5 | 1042 | break; |
1043 | ||
65f34de5 | 1044 | /* Don't begin a cross-jump with a USE or CLOBBER insn. */ |
ba38e12b | 1045 | if (active_insn_p (i1)) |
65f34de5 | 1046 | { |
ab33a25a | 1047 | /* If the merged insns have different REG_EQUAL notes, then |
1048 | remove them. */ | |
1049 | rtx equiv1 = find_reg_equal_equiv_note (i1); | |
1050 | rtx equiv2 = find_reg_equal_equiv_note (i2); | |
1051 | ||
1052 | if (equiv1 && !equiv2) | |
1053 | remove_note (i1, equiv1); | |
1054 | else if (!equiv1 && equiv2) | |
1055 | remove_note (i2, equiv2); | |
1056 | else if (equiv1 && equiv2 | |
1057 | && !rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0))) | |
1058 | { | |
1059 | remove_note (i1, equiv1); | |
1060 | remove_note (i2, equiv2); | |
1061 | } | |
db34a109 | 1062 | |
65f34de5 | 1063 | afterlast1 = last1, afterlast2 = last2; |
1064 | last1 = i1, last2 = i2; | |
db34a109 | 1065 | ninsns++; |
65f34de5 | 1066 | } |
5cc577b6 | 1067 | |
65f34de5 | 1068 | i1 = PREV_INSN (i1); |
1069 | i2 = PREV_INSN (i2); | |
1070 | } | |
1071 | ||
1072 | #ifdef HAVE_cc0 | |
5cc577b6 | 1073 | /* Don't allow the insn after a compare to be shared by |
1074 | cross-jumping unless the compare is also shared. */ | |
1075 | if (ninsns && reg_mentioned_p (cc0_rtx, last1) && ! sets_cc0_p (last1)) | |
1076 | last1 = afterlast1, last2 = afterlast2, ninsns--; | |
65f34de5 | 1077 | #endif |
1078 | ||
4a82352a | 1079 | /* Include preceding notes and labels in the cross-jump. One, |
65f34de5 | 1080 | this may bring us to the head of the blocks as requested above. |
1081 | Two, it keeps line number notes as matched as may be. */ | |
1082 | if (ninsns) | |
1083 | { | |
a716a89b | 1084 | while (last1 != bb1->head && !active_insn_p (PREV_INSN (last1))) |
65f34de5 | 1085 | last1 = PREV_INSN (last1); |
5cc577b6 | 1086 | |
65f34de5 | 1087 | if (last1 != bb1->head && GET_CODE (PREV_INSN (last1)) == CODE_LABEL) |
1088 | last1 = PREV_INSN (last1); | |
5cc577b6 | 1089 | |
a716a89b | 1090 | while (last2 != bb2->head && !active_insn_p (PREV_INSN (last2))) |
65f34de5 | 1091 | last2 = PREV_INSN (last2); |
5cc577b6 | 1092 | |
65f34de5 | 1093 | if (last2 != bb2->head && GET_CODE (PREV_INSN (last2)) == CODE_LABEL) |
1094 | last2 = PREV_INSN (last2); | |
1095 | ||
1096 | *f1 = last1; | |
1097 | *f2 = last2; | |
1098 | } | |
1099 | ||
1100 | return ninsns; | |
1101 | } | |
1102 | ||
1103 | /* Return true iff outgoing edges of BB1 and BB2 match, together with | |
1104 | the branch instruction. This means that if we commonize the control | |
1105 | flow before end of the basic block, the semantic remains unchanged. | |
1106 | ||
1107 | We may assume that there exists one edge with a common destination. */ | |
1108 | ||
1109 | static bool | |
ba38e12b | 1110 | outgoing_edges_match (mode, bb1, bb2) |
1111 | int mode; | |
65f34de5 | 1112 | basic_block bb1; |
1113 | basic_block bb2; | |
1114 | { | |
ba38e12b | 1115 | int nehedges1 = 0, nehedges2 = 0; |
1116 | edge fallthru1 = 0, fallthru2 = 0; | |
1117 | edge e1, e2; | |
1118 | ||
337b10d0 | 1119 | /* If BB1 has only one successor, we may be looking at either an |
1120 | unconditional jump, or a fake edge to exit. */ | |
3bf090f7 | 1121 | if (bb1->succ && !bb1->succ->succ_next |
1122 | && !(bb1->succ->flags & (EDGE_COMPLEX | EDGE_FAKE))) | |
5cc577b6 | 1123 | return (bb2->succ && !bb2->succ->succ_next |
1124 | && (bb2->succ->flags & (EDGE_COMPLEX | EDGE_FAKE)) == 0); | |
65f34de5 | 1125 | |
1126 | /* Match conditional jumps - this may get tricky when fallthru and branch | |
1127 | edges are crossed. */ | |
1128 | if (bb1->succ | |
1129 | && bb1->succ->succ_next | |
1130 | && !bb1->succ->succ_next->succ_next | |
3bf090f7 | 1131 | && any_condjump_p (bb1->end) |
1132 | && onlyjump_p (bb1->end)) | |
65f34de5 | 1133 | { |
1134 | edge b1, f1, b2, f2; | |
1135 | bool reverse, match; | |
1136 | rtx set1, set2, cond1, cond2; | |
1137 | enum rtx_code code1, code2; | |
1138 | ||
1139 | if (!bb2->succ | |
db34a109 | 1140 | || !bb2->succ->succ_next |
26fb1781 | 1141 | || bb2->succ->succ_next->succ_next |
3bf090f7 | 1142 | || !any_condjump_p (bb2->end) |
26fb1781 | 1143 | || !onlyjump_p (bb2->end)) |
1144 | return false; | |
1145 | ||
1146 | /* Do not crossjump across loop boundaries. This is a temporary | |
1147 | workaround for the common scenario in which crossjumping results | |
1148 | in killing the duplicated loop condition, making bb-reorder rotate | |
1149 | the loop incorectly, leaving an extra unconditional jump inside | |
1150 | the loop. | |
1151 | ||
1152 | This check should go away once bb-reorder knows how to duplicate | |
1153 | code in this case or rotate the loops to avoid this scenario. */ | |
1154 | if (bb1->loop_depth != bb2->loop_depth) | |
65f34de5 | 1155 | return false; |
1156 | ||
1157 | b1 = BRANCH_EDGE (bb1); | |
1158 | b2 = BRANCH_EDGE (bb2); | |
1159 | f1 = FALLTHRU_EDGE (bb1); | |
1160 | f2 = FALLTHRU_EDGE (bb2); | |
1161 | ||
1162 | /* Get around possible forwarders on fallthru edges. Other cases | |
1163 | should be optimized out already. */ | |
33dbe4d1 | 1164 | if (FORWARDER_BLOCK_P (f1->dest)) |
65f34de5 | 1165 | f1 = f1->dest->succ; |
5cc577b6 | 1166 | |
33dbe4d1 | 1167 | if (FORWARDER_BLOCK_P (f2->dest)) |
65f34de5 | 1168 | f2 = f2->dest->succ; |
1169 | ||
1170 | /* To simplify use of this function, return false if there are | |
1171 | unneeded forwarder blocks. These will get eliminated later | |
1172 | during cleanup_cfg. */ | |
33dbe4d1 | 1173 | if (FORWARDER_BLOCK_P (f1->dest) |
1174 | || FORWARDER_BLOCK_P (f2->dest) | |
1175 | || FORWARDER_BLOCK_P (b1->dest) | |
1176 | || FORWARDER_BLOCK_P (b2->dest)) | |
65f34de5 | 1177 | return false; |
1178 | ||
1179 | if (f1->dest == f2->dest && b1->dest == b2->dest) | |
1180 | reverse = false; | |
1181 | else if (f1->dest == b2->dest && b1->dest == f2->dest) | |
1182 | reverse = true; | |
1183 | else | |
1184 | return false; | |
1185 | ||
1186 | set1 = pc_set (bb1->end); | |
1187 | set2 = pc_set (bb2->end); | |
1188 | if ((XEXP (SET_SRC (set1), 1) == pc_rtx) | |
1189 | != (XEXP (SET_SRC (set2), 1) == pc_rtx)) | |
1190 | reverse = !reverse; | |
1191 | ||
1192 | cond1 = XEXP (SET_SRC (set1), 0); | |
1193 | cond2 = XEXP (SET_SRC (set2), 0); | |
1194 | code1 = GET_CODE (cond1); | |
1195 | if (reverse) | |
1196 | code2 = reversed_comparison_code (cond2, bb2->end); | |
1197 | else | |
1198 | code2 = GET_CODE (cond2); | |
5cc577b6 | 1199 | |
65f34de5 | 1200 | if (code2 == UNKNOWN) |
1201 | return false; | |
1202 | ||
1203 | /* Verify codes and operands match. */ | |
1204 | match = ((code1 == code2 | |
1205 | && rtx_renumbered_equal_p (XEXP (cond1, 0), XEXP (cond2, 0)) | |
1206 | && rtx_renumbered_equal_p (XEXP (cond1, 1), XEXP (cond2, 1))) | |
1207 | || (code1 == swap_condition (code2) | |
1208 | && rtx_renumbered_equal_p (XEXP (cond1, 1), | |
1209 | XEXP (cond2, 0)) | |
1210 | && rtx_renumbered_equal_p (XEXP (cond1, 0), | |
1211 | XEXP (cond2, 1)))); | |
1212 | ||
1213 | /* If we return true, we will join the blocks. Which means that | |
1214 | we will only have one branch prediction bit to work with. Thus | |
1215 | we require the existing branches to have probabilities that are | |
1216 | roughly similar. */ | |
f884e43f | 1217 | if (match |
1218 | && !optimize_size | |
429fa7fa | 1219 | && maybe_hot_bb_p (bb1) |
1220 | && maybe_hot_bb_p (bb2)) | |
65f34de5 | 1221 | { |
f884e43f | 1222 | int prob2; |
5cc577b6 | 1223 | |
f884e43f | 1224 | if (b1->dest == b2->dest) |
1225 | prob2 = b2->probability; | |
1226 | else | |
1227 | /* Do not use f2 probability as f2 may be forwarded. */ | |
1228 | prob2 = REG_BR_PROB_BASE - b2->probability; | |
65f34de5 | 1229 | |
26fb1781 | 1230 | /* Fail if the difference in probabilities is greater than 50%. |
1231 | This rules out two well-predicted branches with opposite | |
1232 | outcomes. */ | |
6e304f51 | 1233 | if (abs (b1->probability - prob2) > REG_BR_PROB_BASE / 2) |
65f34de5 | 1234 | { |
f884e43f | 1235 | if (rtl_dump_file) |
1236 | fprintf (rtl_dump_file, | |
1237 | "Outcomes of branch in bb %i and %i differs to much (%i %i)\n", | |
b3d6de89 | 1238 | bb1->index, bb2->index, b1->probability, prob2); |
5cc577b6 | 1239 | |
f884e43f | 1240 | return false; |
1241 | } | |
65f34de5 | 1242 | } |
1243 | ||
1244 | if (rtl_dump_file && match) | |
1245 | fprintf (rtl_dump_file, "Conditionals in bb %i and %i match.\n", | |
b3d6de89 | 1246 | bb1->index, bb2->index); |
65f34de5 | 1247 | |
1248 | return match; | |
1249 | } | |
1250 | ||
edc2a478 | 1251 | /* Generic case - we are seeing a computed jump, table jump or trapping |
ba38e12b | 1252 | instruction. */ |
1253 | ||
1254 | /* First ensure that the instructions match. There may be many outgoing | |
1255 | edges so this test is generally cheaper. | |
1256 | ??? Currently the tablejumps will never match, as they do have | |
1257 | different tables. */ | |
1258 | if (!insns_match_p (mode, bb1->end, bb2->end)) | |
1259 | return false; | |
1260 | ||
1261 | /* Search the outgoing edges, ensure that the counts do match, find possible | |
1262 | fallthru and exception handling edges since these needs more | |
1263 | validation. */ | |
1264 | for (e1 = bb1->succ, e2 = bb2->succ; e1 && e2; | |
1265 | e1 = e1->succ_next, e2 = e2->succ_next) | |
1266 | { | |
1267 | if (e1->flags & EDGE_EH) | |
1268 | nehedges1++; | |
5cc577b6 | 1269 | |
ba38e12b | 1270 | if (e2->flags & EDGE_EH) |
1271 | nehedges2++; | |
5cc577b6 | 1272 | |
ba38e12b | 1273 | if (e1->flags & EDGE_FALLTHRU) |
1274 | fallthru1 = e1; | |
1275 | if (e2->flags & EDGE_FALLTHRU) | |
1276 | fallthru2 = e2; | |
1277 | } | |
5cc577b6 | 1278 | |
ba38e12b | 1279 | /* If number of edges of various types does not match, fail. */ |
5cc577b6 | 1280 | if (e1 || e2 |
1281 | || nehedges1 != nehedges2 | |
1282 | || (fallthru1 != 0) != (fallthru2 != 0)) | |
ba38e12b | 1283 | return false; |
1284 | ||
1285 | /* fallthru edges must be forwarded to the same destination. */ | |
1286 | if (fallthru1) | |
1287 | { | |
1288 | basic_block d1 = (forwarder_block_p (fallthru1->dest) | |
db34a109 | 1289 | ? fallthru1->dest->succ->dest: fallthru1->dest); |
ba38e12b | 1290 | basic_block d2 = (forwarder_block_p (fallthru2->dest) |
db34a109 | 1291 | ? fallthru2->dest->succ->dest: fallthru2->dest); |
5cc577b6 | 1292 | |
ba38e12b | 1293 | if (d1 != d2) |
1294 | return false; | |
1295 | } | |
5cc577b6 | 1296 | |
ba38e12b | 1297 | /* In case we do have EH edges, ensure we are in the same region. */ |
1298 | if (nehedges1) | |
1299 | { | |
1300 | rtx n1 = find_reg_note (bb1->end, REG_EH_REGION, 0); | |
1301 | rtx n2 = find_reg_note (bb2->end, REG_EH_REGION, 0); | |
5cc577b6 | 1302 | |
ba38e12b | 1303 | if (XEXP (n1, 0) != XEXP (n2, 0)) |
1304 | return false; | |
1305 | } | |
5cc577b6 | 1306 | |
ba38e12b | 1307 | /* We don't need to match the rest of edges as above checks should be enought |
1308 | to ensure that they are equivalent. */ | |
1309 | return true; | |
65f34de5 | 1310 | } |
1311 | ||
1312 | /* E1 and E2 are edges with the same destination block. Search their | |
1313 | predecessors for common code. If found, redirect control flow from | |
1314 | (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC. */ | |
1315 | ||
1316 | static bool | |
1317 | try_crossjump_to_edge (mode, e1, e2) | |
1318 | int mode; | |
1319 | edge e1, e2; | |
1320 | { | |
1321 | int nmatch; | |
1322 | basic_block src1 = e1->src, src2 = e2->src; | |
42e9bc25 | 1323 | basic_block redirect_to, redirect_from, to_remove; |
65f34de5 | 1324 | rtx newpos1, newpos2; |
1325 | edge s; | |
65f34de5 | 1326 | |
1327 | /* Search backward through forwarder blocks. We don't need to worry | |
1328 | about multiple entry or chained forwarders, as they will be optimized | |
1329 | away. We do this to look past the unconditional jump following a | |
1330 | conditional jump that is required due to the current CFG shape. */ | |
1331 | if (src1->pred | |
1332 | && !src1->pred->pred_next | |
33dbe4d1 | 1333 | && FORWARDER_BLOCK_P (src1)) |
5cc577b6 | 1334 | e1 = src1->pred, src1 = e1->src; |
1335 | ||
65f34de5 | 1336 | if (src2->pred |
1337 | && !src2->pred->pred_next | |
33dbe4d1 | 1338 | && FORWARDER_BLOCK_P (src2)) |
5cc577b6 | 1339 | e2 = src2->pred, src2 = e2->src; |
65f34de5 | 1340 | |
1341 | /* Nothing to do if we reach ENTRY, or a common source block. */ | |
1342 | if (src1 == ENTRY_BLOCK_PTR || src2 == ENTRY_BLOCK_PTR) | |
1343 | return false; | |
1344 | if (src1 == src2) | |
1345 | return false; | |
1346 | ||
1347 | /* Seeing more than 1 forwarder blocks would confuse us later... */ | |
33dbe4d1 | 1348 | if (FORWARDER_BLOCK_P (e1->dest) |
1349 | && FORWARDER_BLOCK_P (e1->dest->succ->dest)) | |
65f34de5 | 1350 | return false; |
5cc577b6 | 1351 | |
33dbe4d1 | 1352 | if (FORWARDER_BLOCK_P (e2->dest) |
1353 | && FORWARDER_BLOCK_P (e2->dest->succ->dest)) | |
65f34de5 | 1354 | return false; |
1355 | ||
1356 | /* Likewise with dead code (possibly newly created by the other optimizations | |
1357 | of cfg_cleanup). */ | |
1358 | if (!src1->pred || !src2->pred) | |
1359 | return false; | |
1360 | ||
65f34de5 | 1361 | /* Look for the common insn sequence, part the first ... */ |
ba38e12b | 1362 | if (!outgoing_edges_match (mode, src1, src2)) |
65f34de5 | 1363 | return false; |
1364 | ||
1365 | /* ... and part the second. */ | |
1366 | nmatch = flow_find_cross_jump (mode, src1, src2, &newpos1, &newpos2); | |
1367 | if (!nmatch) | |
1368 | return false; | |
1369 | ||
1370 | /* Avoid splitting if possible. */ | |
1371 | if (newpos2 == src2->head) | |
1372 | redirect_to = src2; | |
1373 | else | |
1374 | { | |
1375 | if (rtl_dump_file) | |
1376 | fprintf (rtl_dump_file, "Splitting bb %i before %i insns\n", | |
b3d6de89 | 1377 | src2->index, nmatch); |
65f34de5 | 1378 | redirect_to = split_block (src2, PREV_INSN (newpos2))->dest; |
1379 | } | |
1380 | ||
1381 | if (rtl_dump_file) | |
1382 | fprintf (rtl_dump_file, | |
1383 | "Cross jumping from bb %i to bb %i; %i common insns\n", | |
b3d6de89 | 1384 | src1->index, src2->index, nmatch); |
65f34de5 | 1385 | |
1386 | redirect_to->count += src1->count; | |
1387 | redirect_to->frequency += src1->frequency; | |
f760eb7d | 1388 | /* We may have some registers visible trought the block. */ |
1389 | redirect_to->flags |= BB_DIRTY; | |
65f34de5 | 1390 | |
1391 | /* Recompute the frequencies and counts of outgoing edges. */ | |
1392 | for (s = redirect_to->succ; s; s = s->succ_next) | |
1393 | { | |
1394 | edge s2; | |
1395 | basic_block d = s->dest; | |
1396 | ||
33dbe4d1 | 1397 | if (FORWARDER_BLOCK_P (d)) |
65f34de5 | 1398 | d = d->succ->dest; |
5cc577b6 | 1399 | |
65f34de5 | 1400 | for (s2 = src1->succ; ; s2 = s2->succ_next) |
1401 | { | |
1402 | basic_block d2 = s2->dest; | |
33dbe4d1 | 1403 | if (FORWARDER_BLOCK_P (d2)) |
65f34de5 | 1404 | d2 = d2->succ->dest; |
1405 | if (d == d2) | |
1406 | break; | |
1407 | } | |
5cc577b6 | 1408 | |
65f34de5 | 1409 | s->count += s2->count; |
1410 | ||
1411 | /* Take care to update possible forwarder blocks. We verified | |
1412 | that there is no more than one in the chain, so we can't run | |
1413 | into infinite loop. */ | |
33dbe4d1 | 1414 | if (FORWARDER_BLOCK_P (s->dest)) |
65f34de5 | 1415 | { |
1416 | s->dest->succ->count += s2->count; | |
1417 | s->dest->count += s2->count; | |
1418 | s->dest->frequency += EDGE_FREQUENCY (s); | |
1419 | } | |
5cc577b6 | 1420 | |
33dbe4d1 | 1421 | if (FORWARDER_BLOCK_P (s2->dest)) |
65f34de5 | 1422 | { |
1423 | s2->dest->succ->count -= s2->count; | |
f884e43f | 1424 | if (s2->dest->succ->count < 0) |
1425 | s2->dest->succ->count = 0; | |
65f34de5 | 1426 | s2->dest->count -= s2->count; |
1427 | s2->dest->frequency -= EDGE_FREQUENCY (s); | |
f884e43f | 1428 | if (s2->dest->frequency < 0) |
1429 | s2->dest->frequency = 0; | |
1430 | if (s2->dest->count < 0) | |
1431 | s2->dest->count = 0; | |
65f34de5 | 1432 | } |
5cc577b6 | 1433 | |
65f34de5 | 1434 | if (!redirect_to->frequency && !src1->frequency) |
1435 | s->probability = (s->probability + s2->probability) / 2; | |
1436 | else | |
5cc577b6 | 1437 | s->probability |
1438 | = ((s->probability * redirect_to->frequency + | |
1439 | s2->probability * src1->frequency) | |
1440 | / (redirect_to->frequency + src1->frequency)); | |
65f34de5 | 1441 | } |
1442 | ||
f884e43f | 1443 | update_br_prob_note (redirect_to); |
65f34de5 | 1444 | |
1445 | /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */ | |
1446 | ||
1447 | /* Skip possible basic block header. */ | |
1448 | if (GET_CODE (newpos1) == CODE_LABEL) | |
1449 | newpos1 = NEXT_INSN (newpos1); | |
5cc577b6 | 1450 | |
65f34de5 | 1451 | if (GET_CODE (newpos1) == NOTE) |
1452 | newpos1 = NEXT_INSN (newpos1); | |
65f34de5 | 1453 | |
42e9bc25 | 1454 | redirect_from = split_block (src1, PREV_INSN (newpos1))->src; |
1455 | to_remove = redirect_from->succ->dest; | |
65f34de5 | 1456 | |
42e9bc25 | 1457 | redirect_edge_and_branch_force (redirect_from->succ, redirect_to); |
1458 | flow_delete_block (to_remove); | |
65f34de5 | 1459 | |
42e9bc25 | 1460 | update_forwarder_flag (redirect_from); |
33dbe4d1 | 1461 | |
65f34de5 | 1462 | return true; |
1463 | } | |
1464 | ||
1465 | /* Search the predecessors of BB for common insn sequences. When found, | |
1466 | share code between them by redirecting control flow. Return true if | |
1467 | any changes made. */ | |
1468 | ||
1469 | static bool | |
1470 | try_crossjump_bb (mode, bb) | |
1471 | int mode; | |
1472 | basic_block bb; | |
1473 | { | |
1474 | edge e, e2, nexte2, nexte, fallthru; | |
1475 | bool changed; | |
350b17ef | 1476 | int n = 0; |
65f34de5 | 1477 | |
dd5b4b36 | 1478 | /* Nothing to do if there is not at least two incoming edges. */ |
65f34de5 | 1479 | if (!bb->pred || !bb->pred->pred_next) |
1480 | return false; | |
1481 | ||
1482 | /* It is always cheapest to redirect a block that ends in a branch to | |
1483 | a block that falls through into BB, as that adds no branches to the | |
1484 | program. We'll try that combination first. */ | |
350b17ef | 1485 | for (fallthru = bb->pred; fallthru; fallthru = fallthru->pred_next, n++) |
1486 | { | |
1487 | if (fallthru->flags & EDGE_FALLTHRU) | |
1488 | break; | |
1489 | if (n > 100) | |
1490 | return false; | |
1491 | } | |
65f34de5 | 1492 | |
1493 | changed = false; | |
1494 | for (e = bb->pred; e; e = nexte) | |
1495 | { | |
1496 | nexte = e->pred_next; | |
1497 | ||
65f34de5 | 1498 | /* As noted above, first try with the fallthru predecessor. */ |
1499 | if (fallthru) | |
1500 | { | |
1501 | /* Don't combine the fallthru edge into anything else. | |
1502 | If there is a match, we'll do it the other way around. */ | |
1503 | if (e == fallthru) | |
1504 | continue; | |
1505 | ||
1506 | if (try_crossjump_to_edge (mode, e, fallthru)) | |
1507 | { | |
1508 | changed = true; | |
1509 | nexte = bb->pred; | |
1510 | continue; | |
1511 | } | |
1512 | } | |
1513 | ||
1514 | /* Non-obvious work limiting check: Recognize that we're going | |
1515 | to call try_crossjump_bb on every basic block. So if we have | |
1516 | two blocks with lots of outgoing edges (a switch) and they | |
1517 | share lots of common destinations, then we would do the | |
1518 | cross-jump check once for each common destination. | |
1519 | ||
1520 | Now, if the blocks actually are cross-jump candidates, then | |
1521 | all of their destinations will be shared. Which means that | |
1522 | we only need check them for cross-jump candidacy once. We | |
1523 | can eliminate redundant checks of crossjump(A,B) by arbitrarily | |
1524 | choosing to do the check from the block for which the edge | |
1525 | in question is the first successor of A. */ | |
1526 | if (e->src->succ != e) | |
1527 | continue; | |
1528 | ||
1529 | for (e2 = bb->pred; e2; e2 = nexte2) | |
1530 | { | |
1531 | nexte2 = e2->pred_next; | |
1532 | ||
1533 | if (e2 == e) | |
1534 | continue; | |
1535 | ||
1536 | /* We've already checked the fallthru edge above. */ | |
1537 | if (e2 == fallthru) | |
1538 | continue; | |
1539 | ||
65f34de5 | 1540 | /* The "first successor" check above only prevents multiple |
1541 | checks of crossjump(A,B). In order to prevent redundant | |
1542 | checks of crossjump(B,A), require that A be the block | |
1543 | with the lowest index. */ | |
b3d6de89 | 1544 | if (e->src->index > e2->src->index) |
65f34de5 | 1545 | continue; |
1546 | ||
1547 | if (try_crossjump_to_edge (mode, e, e2)) | |
1548 | { | |
1549 | changed = true; | |
1550 | nexte = bb->pred; | |
1551 | break; | |
1552 | } | |
1553 | } | |
1554 | } | |
1555 | ||
1556 | return changed; | |
1557 | } | |
1558 | ||
1559 | /* Do simple CFG optimizations - basic block merging, simplifying of jump | |
1560 | instructions etc. Return nonzero if changes were made. */ | |
1561 | ||
1562 | static bool | |
1563 | try_optimize_cfg (mode) | |
1564 | int mode; | |
1565 | { | |
65f34de5 | 1566 | bool changed_overall = false; |
1567 | bool changed; | |
1568 | int iterations = 0; | |
4c26117a | 1569 | basic_block bb, b; |
65f34de5 | 1570 | |
b36d64df | 1571 | if (mode & CLEANUP_CROSSJUMP) |
1572 | add_noreturn_fake_exit_edges (); | |
1573 | ||
4c26117a | 1574 | FOR_EACH_BB (bb) |
1575 | update_forwarder_flag (bb); | |
33dbe4d1 | 1576 | |
308f9b79 | 1577 | if (mode & CLEANUP_UPDATE_LIFE) |
1578 | clear_bb_flags (); | |
1579 | ||
e27e52e0 | 1580 | if (! (* targetm.cannot_modify_jumps_p) ()) |
65f34de5 | 1581 | { |
e27e52e0 | 1582 | /* Attempt to merge blocks as made possible by edge removal. If |
1583 | a block has only one successor, and the successor has only | |
1584 | one predecessor, they may be combined. */ | |
1585 | do | |
65f34de5 | 1586 | { |
e27e52e0 | 1587 | changed = false; |
1588 | iterations++; | |
1589 | ||
1590 | if (rtl_dump_file) | |
1591 | fprintf (rtl_dump_file, | |
1592 | "\n\ntry_optimize_cfg iteration %i\n\n", | |
1593 | iterations); | |
65f34de5 | 1594 | |
4c26117a | 1595 | for (b = ENTRY_BLOCK_PTR->next_bb; b != EXIT_BLOCK_PTR;) |
65f34de5 | 1596 | { |
4c26117a | 1597 | basic_block c; |
e27e52e0 | 1598 | edge s; |
1599 | bool changed_here = false; | |
5cc577b6 | 1600 | |
e27e52e0 | 1601 | /* Delete trivially dead basic blocks. */ |
1602 | while (b->pred == NULL) | |
1603 | { | |
345ac34a | 1604 | c = b->prev_bb; |
e27e52e0 | 1605 | if (rtl_dump_file) |
1606 | fprintf (rtl_dump_file, "Deleting block %i.\n", | |
b3d6de89 | 1607 | b->index); |
e27e52e0 | 1608 | |
1609 | flow_delete_block (b); | |
1610 | changed = true; | |
1611 | b = c; | |
1612 | } | |
65f34de5 | 1613 | |
e27e52e0 | 1614 | /* Remove code labels no longer used. Don't do this |
1615 | before CALL_PLACEHOLDER is removed, as some branches | |
1616 | may be hidden within. */ | |
1617 | if (b->pred->pred_next == NULL | |
1618 | && (b->pred->flags & EDGE_FALLTHRU) | |
1619 | && !(b->pred->flags & EDGE_COMPLEX) | |
1620 | && GET_CODE (b->head) == CODE_LABEL | |
1621 | && (!(mode & CLEANUP_PRE_SIBCALL) | |
1622 | || !tail_recursion_label_p (b->head)) | |
1623 | /* If the previous block ends with a branch to this | |
1624 | block, we can't delete the label. Normally this | |
1625 | is a condjump that is yet to be simplified, but | |
1626 | if CASE_DROPS_THRU, this can be a tablejump with | |
1627 | some element going to the same place as the | |
1628 | default (fallthru). */ | |
1629 | && (b->pred->src == ENTRY_BLOCK_PTR | |
1630 | || GET_CODE (b->pred->src->end) != JUMP_INSN | |
1631 | || ! label_is_jump_target_p (b->head, | |
1632 | b->pred->src->end))) | |
1633 | { | |
1634 | rtx label = b->head; | |
5cc577b6 | 1635 | |
e27e52e0 | 1636 | b->head = NEXT_INSN (b->head); |
1637 | delete_insn_chain (label, label); | |
1638 | if (rtl_dump_file) | |
1639 | fprintf (rtl_dump_file, "Deleted label in block %i.\n", | |
b3d6de89 | 1640 | b->index); |
e27e52e0 | 1641 | } |
65f34de5 | 1642 | |
e27e52e0 | 1643 | /* If we fall through an empty block, we can remove it. */ |
1644 | if (b->pred->pred_next == NULL | |
1645 | && (b->pred->flags & EDGE_FALLTHRU) | |
1646 | && GET_CODE (b->head) != CODE_LABEL | |
1647 | && FORWARDER_BLOCK_P (b) | |
1648 | /* Note that forwarder_block_p true ensures that | |
1649 | there is a successor for this block. */ | |
1650 | && (b->succ->flags & EDGE_FALLTHRU) | |
b3d6de89 | 1651 | && n_basic_blocks > 1) |
e27e52e0 | 1652 | { |
1653 | if (rtl_dump_file) | |
1654 | fprintf (rtl_dump_file, | |
1655 | "Deleting fallthru block %i.\n", | |
b3d6de89 | 1656 | b->index); |
e27e52e0 | 1657 | |
345ac34a | 1658 | c = b->prev_bb == ENTRY_BLOCK_PTR ? b->next_bb : b->prev_bb; |
e27e52e0 | 1659 | redirect_edge_succ_nodup (b->pred, b->succ->dest); |
1660 | flow_delete_block (b); | |
1661 | changed = true; | |
1662 | b = c; | |
1663 | } | |
5cc577b6 | 1664 | |
e27e52e0 | 1665 | /* Merge blocks. Loop because chains of blocks might be |
1666 | combineable. */ | |
1667 | while ((s = b->succ) != NULL | |
1668 | && s->succ_next == NULL | |
1669 | && !(s->flags & EDGE_COMPLEX) | |
1670 | && (c = s->dest) != EXIT_BLOCK_PTR | |
1671 | && c->pred->pred_next == NULL | |
79e9c596 | 1672 | && b != c |
e27e52e0 | 1673 | /* If the jump insn has side effects, |
1674 | we can't kill the edge. */ | |
1675 | && (GET_CODE (b->end) != JUMP_INSN | |
41a4ba7f | 1676 | || simplejump_p (b->end)) |
e27e52e0 | 1677 | && merge_blocks (s, b, c, mode)) |
1678 | changed_here = true; | |
1679 | ||
1680 | /* Simplify branch over branch. */ | |
1681 | if ((mode & CLEANUP_EXPENSIVE) && try_simplify_condjump (b)) | |
308f9b79 | 1682 | changed_here = true; |
65f34de5 | 1683 | |
e27e52e0 | 1684 | /* If B has a single outgoing edge, but uses a |
1685 | non-trivial jump instruction without side-effects, we | |
1686 | can either delete the jump entirely, or replace it | |
1687 | with a simple unconditional jump. Use | |
1688 | redirect_edge_and_branch to do the dirty work. */ | |
1689 | if (b->succ | |
1690 | && ! b->succ->succ_next | |
1691 | && b->succ->dest != EXIT_BLOCK_PTR | |
1692 | && onlyjump_p (b->end) | |
1693 | && redirect_edge_and_branch (b->succ, b->succ->dest)) | |
1694 | { | |
e27e52e0 | 1695 | update_forwarder_flag (b); |
1696 | changed_here = true; | |
1697 | } | |
65f34de5 | 1698 | |
e27e52e0 | 1699 | /* Simplify branch to branch. */ |
1700 | if (try_forward_edges (mode, b)) | |
1701 | changed_here = true; | |
65f34de5 | 1702 | |
e27e52e0 | 1703 | /* Look for shared code between blocks. */ |
1704 | if ((mode & CLEANUP_CROSSJUMP) | |
1705 | && try_crossjump_bb (mode, b)) | |
1706 | changed_here = true; | |
65f34de5 | 1707 | |
e27e52e0 | 1708 | /* Don't get confused by the index shift caused by |
1709 | deleting blocks. */ | |
1710 | if (!changed_here) | |
4c26117a | 1711 | b = b->next_bb; |
e27e52e0 | 1712 | else |
1713 | changed = true; | |
1714 | } | |
65f34de5 | 1715 | |
e27e52e0 | 1716 | if ((mode & CLEANUP_CROSSJUMP) |
1717 | && try_crossjump_bb (mode, EXIT_BLOCK_PTR)) | |
65f34de5 | 1718 | changed = true; |
65f34de5 | 1719 | |
1720 | #ifdef ENABLE_CHECKING | |
e27e52e0 | 1721 | if (changed) |
1722 | verify_flow_info (); | |
65f34de5 | 1723 | #endif |
1724 | ||
e27e52e0 | 1725 | changed_overall |= changed; |
1726 | } | |
1727 | while (changed); | |
65f34de5 | 1728 | } |
b36d64df | 1729 | |
1730 | if (mode & CLEANUP_CROSSJUMP) | |
1731 | remove_fake_edges (); | |
1732 | ||
73e2b81c | 1733 | clear_aux_for_blocks (); |
33dbe4d1 | 1734 | |
65f34de5 | 1735 | return changed_overall; |
1736 | } | |
1737 | \f | |
1e625a2e | 1738 | /* Delete all unreachable basic blocks. */ |
e76f35e8 | 1739 | |
cd0fe062 | 1740 | bool |
65f34de5 | 1741 | delete_unreachable_blocks () |
1742 | { | |
65f34de5 | 1743 | bool changed = false; |
4c26117a | 1744 | basic_block b, next_bb; |
65f34de5 | 1745 | |
1746 | find_unreachable_blocks (); | |
1747 | ||
3c0a32c9 | 1748 | /* Delete all unreachable basic blocks. */ |
65f34de5 | 1749 | |
4c26117a | 1750 | for (b = ENTRY_BLOCK_PTR->next_bb; b != EXIT_BLOCK_PTR; b = next_bb) |
65f34de5 | 1751 | { |
4c26117a | 1752 | next_bb = b->next_bb; |
b3d6de89 | 1753 | |
65f34de5 | 1754 | if (!(b->flags & BB_REACHABLE)) |
8f8dcce4 | 1755 | { |
3c0a32c9 | 1756 | flow_delete_block (b); |
8f8dcce4 | 1757 | changed = true; |
1758 | } | |
65f34de5 | 1759 | } |
1760 | ||
1761 | if (changed) | |
1762 | tidy_fallthru_edges (); | |
1763 | return changed; | |
1764 | } | |
65f34de5 | 1765 | \f |
1766 | /* Tidy the CFG by deleting unreachable code and whatnot. */ | |
1767 | ||
1768 | bool | |
1769 | cleanup_cfg (mode) | |
1770 | int mode; | |
1771 | { | |
65f34de5 | 1772 | bool changed = false; |
1773 | ||
1774 | timevar_push (TV_CLEANUP_CFG); | |
fb20d6fa | 1775 | if (delete_unreachable_blocks ()) |
1776 | { | |
1777 | changed = true; | |
1778 | /* We've possibly created trivially dead code. Cleanup it right | |
1779 | now to introduce more oppurtunities for try_optimize_cfg. */ | |
43a852ea | 1780 | if (!(mode & (CLEANUP_NO_INSN_DEL |
1781 | | CLEANUP_UPDATE_LIFE | CLEANUP_PRE_SIBCALL)) | |
fb20d6fa | 1782 | && !reload_completed) |
1783 | delete_trivially_dead_insns (get_insns(), max_reg_num ()); | |
1784 | } | |
3c0a32c9 | 1785 | |
1786 | compact_blocks (); | |
1787 | ||
fb20d6fa | 1788 | while (try_optimize_cfg (mode)) |
1789 | { | |
1790 | delete_unreachable_blocks (), changed = true; | |
1791 | if (mode & CLEANUP_UPDATE_LIFE) | |
1792 | { | |
1793 | /* Cleaning up CFG introduces more oppurtunities for dead code | |
1794 | removal that in turn may introduce more oppurtunities for | |
1795 | cleaning up the CFG. */ | |
5b9c5bf5 | 1796 | if (!update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES, |
fb20d6fa | 1797 | PROP_DEATH_NOTES |
1798 | | PROP_SCAN_DEAD_CODE | |
1799 | | PROP_KILL_DEAD_CODE | |
1800 | | PROP_LOG_LINKS)) | |
1801 | break; | |
1802 | } | |
43a852ea | 1803 | else if (!(mode & (CLEANUP_NO_INSN_DEL | CLEANUP_PRE_SIBCALL)) |
1804 | && !reload_completed) | |
fb20d6fa | 1805 | { |
1806 | if (!delete_trivially_dead_insns (get_insns(), max_reg_num ())) | |
1807 | break; | |
1808 | } | |
1809 | else | |
1810 | break; | |
1811 | delete_dead_jumptables (); | |
1812 | } | |
65f34de5 | 1813 | |
65f34de5 | 1814 | /* Kill the data we won't maintain. */ |
1815 | free_EXPR_LIST_list (&label_value_list); | |
65f34de5 | 1816 | timevar_pop (TV_CLEANUP_CFG); |
1817 | ||
65f34de5 | 1818 | return changed; |
1819 | } |