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3d436d2a | 1 | /* Natural loop analysis code for GNU compiler. |
818ab71a | 2 | Copyright (C) 2002-2016 Free Software Foundation, Inc. |
3d436d2a ZD |
3 | |
4 | This file is part of GCC. | |
5 | ||
6 | GCC is free software; you can redistribute it and/or modify it under | |
7 | the terms of the GNU General Public License as published by the Free | |
9dcd6f09 | 8 | Software Foundation; either version 3, or (at your option) any later |
3d436d2a ZD |
9 | version. |
10 | ||
11 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 | for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
9dcd6f09 NC |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
3d436d2a ZD |
19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
c7131fb2 | 23 | #include "backend.h" |
3d436d2a | 24 | #include "rtl.h" |
c7131fb2 | 25 | #include "tree.h" |
957060b5 | 26 | #include "predict.h" |
4d0cdd0c | 27 | #include "memmodel.h" |
957060b5 AM |
28 | #include "emit-rtl.h" |
29 | #include "cfgloop.h" | |
36566b39 | 30 | #include "explow.h" |
3d436d2a | 31 | #include "expr.h" |
66f97d31 | 32 | #include "graphds.h" |
058e97ec | 33 | #include "params.h" |
3d436d2a | 34 | |
4391924a RS |
35 | struct target_cfgloop default_target_cfgloop; |
36 | #if SWITCHABLE_TARGET | |
37 | struct target_cfgloop *this_target_cfgloop = &default_target_cfgloop; | |
38 | #endif | |
39 | ||
3d436d2a | 40 | /* Checks whether BB is executed exactly once in each LOOP iteration. */ |
f2dca510 | 41 | |
3d436d2a | 42 | bool |
ed7a4b4b | 43 | just_once_each_iteration_p (const struct loop *loop, const_basic_block bb) |
3d436d2a ZD |
44 | { |
45 | /* It must be executed at least once each iteration. */ | |
d47cc544 | 46 | if (!dominated_by_p (CDI_DOMINATORS, loop->latch, bb)) |
3d436d2a ZD |
47 | return false; |
48 | ||
49 | /* And just once. */ | |
50 | if (bb->loop_father != loop) | |
51 | return false; | |
52 | ||
53 | /* But this was not enough. We might have some irreducible loop here. */ | |
54 | if (bb->flags & BB_IRREDUCIBLE_LOOP) | |
55 | return false; | |
56 | ||
57 | return true; | |
58 | } | |
59 | ||
35b07080 ZD |
60 | /* Marks blocks and edges that are part of non-recognized loops; i.e. we |
61 | throw away all latch edges and mark blocks inside any remaining cycle. | |
62 | Everything is a bit complicated due to fact we do not want to do this | |
63 | for parts of cycles that only "pass" through some loop -- i.e. for | |
64 | each cycle, we want to mark blocks that belong directly to innermost | |
cfbe3efe | 65 | loop containing the whole cycle. |
c22cacf3 | 66 | |
cfbe3efe ZD |
67 | LOOPS is the loop tree. */ |
68 | ||
8b1c6fd7 | 69 | #define LOOP_REPR(LOOP) ((LOOP)->num + last_basic_block_for_fn (cfun)) |
cfbe3efe ZD |
70 | #define BB_REPR(BB) ((BB)->index + 1) |
71 | ||
2de58650 | 72 | bool |
d73be268 | 73 | mark_irreducible_loops (void) |
3d436d2a | 74 | { |
3d436d2a | 75 | basic_block act; |
2de58650 | 76 | struct graph_edge *ge; |
cfbe3efe | 77 | edge e; |
628f6a4e | 78 | edge_iterator ei; |
66f97d31 ZD |
79 | int src, dest; |
80 | unsigned depth; | |
cfbe3efe | 81 | struct graph *g; |
0fc822d0 | 82 | int num = number_of_loops (cfun); |
66f97d31 | 83 | struct loop *cloop; |
2de58650 JH |
84 | bool irred_loop_found = false; |
85 | int i; | |
3d436d2a | 86 | |
d51157de ZD |
87 | gcc_assert (current_loops != NULL); |
88 | ||
35b07080 | 89 | /* Reset the flags. */ |
fefa31b5 DM |
90 | FOR_BB_BETWEEN (act, ENTRY_BLOCK_PTR_FOR_FN (cfun), |
91 | EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb) | |
35b07080 ZD |
92 | { |
93 | act->flags &= ~BB_IRREDUCIBLE_LOOP; | |
628f6a4e | 94 | FOR_EACH_EDGE (e, ei, act->succs) |
35b07080 ZD |
95 | e->flags &= ~EDGE_IRREDUCIBLE_LOOP; |
96 | } | |
97 | ||
3d436d2a | 98 | /* Create the edge lists. */ |
8b1c6fd7 | 99 | g = new_graph (last_basic_block_for_fn (cfun) + num); |
cfbe3efe | 100 | |
fefa31b5 DM |
101 | FOR_BB_BETWEEN (act, ENTRY_BLOCK_PTR_FOR_FN (cfun), |
102 | EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb) | |
628f6a4e | 103 | FOR_EACH_EDGE (e, ei, act->succs) |
3d436d2a | 104 | { |
c22cacf3 | 105 | /* Ignore edges to exit. */ |
fefa31b5 | 106 | if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
3d436d2a | 107 | continue; |
cfbe3efe | 108 | |
598ec7bd ZD |
109 | src = BB_REPR (act); |
110 | dest = BB_REPR (e->dest); | |
cfbe3efe | 111 | |
d51157de ZD |
112 | /* Ignore latch edges. */ |
113 | if (e->dest->loop_father->header == e->dest | |
114 | && e->dest->loop_father->latch == act) | |
115 | continue; | |
116 | ||
117 | /* Edges inside a single loop should be left where they are. Edges | |
118 | to subloop headers should lead to representative of the subloop, | |
119 | but from the same place. | |
cfbe3efe | 120 | |
d51157de ZD |
121 | Edges exiting loops should lead from representative |
122 | of the son of nearest common ancestor of the loops in that | |
123 | act lays. */ | |
124 | ||
125 | if (e->dest->loop_father->header == e->dest) | |
126 | dest = LOOP_REPR (e->dest->loop_father); | |
127 | ||
128 | if (!flow_bb_inside_loop_p (act->loop_father, e->dest)) | |
129 | { | |
130 | depth = 1 + loop_depth (find_common_loop (act->loop_father, | |
131 | e->dest->loop_father)); | |
132 | if (depth == loop_depth (act->loop_father)) | |
133 | cloop = act->loop_father; | |
134 | else | |
9771b263 | 135 | cloop = (*act->loop_father->superloops)[depth]; |
d51157de ZD |
136 | |
137 | src = LOOP_REPR (cloop); | |
3d436d2a | 138 | } |
cfbe3efe | 139 | |
66f97d31 | 140 | add_edge (g, src, dest)->data = e; |
3d436d2a ZD |
141 | } |
142 | ||
66f97d31 ZD |
143 | /* Find the strongly connected components. */ |
144 | graphds_scc (g, NULL); | |
3d436d2a | 145 | |
cfbe3efe | 146 | /* Mark the irreducible loops. */ |
2de58650 JH |
147 | for (i = 0; i < g->n_vertices; i++) |
148 | for (ge = g->vertices[i].succ; ge; ge = ge->succ_next) | |
149 | { | |
150 | edge real = (edge) ge->data; | |
151 | /* edge E in graph G is irreducible if it connects two vertices in the | |
152 | same scc. */ | |
153 | ||
154 | /* All edges should lead from a component with higher number to the | |
155 | one with lower one. */ | |
156 | gcc_assert (g->vertices[ge->src].component >= g->vertices[ge->dest].component); | |
157 | ||
158 | if (g->vertices[ge->src].component != g->vertices[ge->dest].component) | |
159 | continue; | |
160 | ||
161 | real->flags |= EDGE_IRREDUCIBLE_LOOP; | |
162 | irred_loop_found = true; | |
163 | if (flow_bb_inside_loop_p (real->src->loop_father, real->dest)) | |
164 | real->src->flags |= BB_IRREDUCIBLE_LOOP; | |
165 | } | |
3d436d2a | 166 | |
cfbe3efe | 167 | free_graph (g); |
3d436d2a | 168 | |
f87000d0 | 169 | loops_state_set (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS); |
2de58650 | 170 | return irred_loop_found; |
3d436d2a ZD |
171 | } |
172 | ||
173 | /* Counts number of insns inside LOOP. */ | |
174 | int | |
ed7a4b4b | 175 | num_loop_insns (const struct loop *loop) |
3d436d2a ZD |
176 | { |
177 | basic_block *bbs, bb; | |
178 | unsigned i, ninsns = 0; | |
1f75b71e | 179 | rtx_insn *insn; |
3d436d2a ZD |
180 | |
181 | bbs = get_loop_body (loop); | |
182 | for (i = 0; i < loop->num_nodes; i++) | |
183 | { | |
184 | bb = bbs[i]; | |
b5b8b0ac AO |
185 | FOR_BB_INSNS (bb, insn) |
186 | if (NONDEBUG_INSN_P (insn)) | |
91f4cfe3 | 187 | ninsns++; |
3d436d2a | 188 | } |
53a51cef JJ |
189 | free (bbs); |
190 | ||
191 | if (!ninsns) | |
192 | ninsns = 1; /* To avoid division by zero. */ | |
d329e058 | 193 | |
3d436d2a ZD |
194 | return ninsns; |
195 | } | |
196 | ||
197 | /* Counts number of insns executed on average per iteration LOOP. */ | |
198 | int | |
ed7a4b4b | 199 | average_num_loop_insns (const struct loop *loop) |
3d436d2a ZD |
200 | { |
201 | basic_block *bbs, bb; | |
202 | unsigned i, binsns, ninsns, ratio; | |
1f75b71e | 203 | rtx_insn *insn; |
3d436d2a ZD |
204 | |
205 | ninsns = 0; | |
206 | bbs = get_loop_body (loop); | |
207 | for (i = 0; i < loop->num_nodes; i++) | |
208 | { | |
209 | bb = bbs[i]; | |
210 | ||
b5b8b0ac AO |
211 | binsns = 0; |
212 | FOR_BB_INSNS (bb, insn) | |
213 | if (NONDEBUG_INSN_P (insn)) | |
91f4cfe3 | 214 | binsns++; |
3d436d2a ZD |
215 | |
216 | ratio = loop->header->frequency == 0 | |
217 | ? BB_FREQ_MAX | |
218 | : (bb->frequency * BB_FREQ_MAX) / loop->header->frequency; | |
219 | ninsns += binsns * ratio; | |
220 | } | |
53a51cef | 221 | free (bbs); |
d329e058 | 222 | |
3d436d2a ZD |
223 | ninsns /= BB_FREQ_MAX; |
224 | if (!ninsns) | |
225 | ninsns = 1; /* To avoid division by zero. */ | |
226 | ||
227 | return ninsns; | |
228 | } | |
229 | ||
ac84e05e ZD |
230 | /* Returns expected number of iterations of LOOP, according to |
231 | measured or guessed profile. No bounding is done on the | |
232 | value. */ | |
233 | ||
234 | gcov_type | |
199b1891 ML |
235 | expected_loop_iterations_unbounded (const struct loop *loop, |
236 | bool *read_profile_p) | |
3d436d2a ZD |
237 | { |
238 | edge e; | |
628f6a4e | 239 | edge_iterator ei; |
97c53806 JH |
240 | gcov_type expected; |
241 | ||
199b1891 ML |
242 | if (read_profile_p) |
243 | *read_profile_p = false; | |
97c53806 | 244 | |
4661839e | 245 | /* If we have no profile at all, use AVG_LOOP_NITER. */ |
97c53806 | 246 | if (profile_status_for_fn (cfun) == PROFILE_ABSENT) |
4661839e | 247 | expected = PARAM_VALUE (PARAM_AVG_LOOP_NITER); |
c1e1a688 | 248 | else if (loop->latch && (loop->latch->count || loop->header->count)) |
3d436d2a | 249 | { |
97c53806 | 250 | gcov_type count_in, count_latch; |
3d436d2a ZD |
251 | |
252 | count_in = 0; | |
253 | count_latch = 0; | |
254 | ||
628f6a4e | 255 | FOR_EACH_EDGE (e, ei, loop->header->preds) |
3d436d2a ZD |
256 | if (e->src == loop->latch) |
257 | count_latch = e->count; | |
258 | else | |
259 | count_in += e->count; | |
260 | ||
261 | if (count_in == 0) | |
c22cacf3 | 262 | expected = count_latch * 2; |
bade3a00 | 263 | else |
199b1891 ML |
264 | { |
265 | expected = (count_latch + count_in - 1) / count_in; | |
266 | if (read_profile_p) | |
267 | *read_profile_p = true; | |
268 | } | |
3d436d2a ZD |
269 | } |
270 | else | |
271 | { | |
272 | int freq_in, freq_latch; | |
273 | ||
274 | freq_in = 0; | |
275 | freq_latch = 0; | |
276 | ||
628f6a4e | 277 | FOR_EACH_EDGE (e, ei, loop->header->preds) |
c1e1a688 ML |
278 | if (flow_bb_inside_loop_p (loop, e->src)) |
279 | freq_latch += EDGE_FREQUENCY (e); | |
3d436d2a ZD |
280 | else |
281 | freq_in += EDGE_FREQUENCY (e); | |
282 | ||
283 | if (freq_in == 0) | |
97c53806 | 284 | { |
4661839e | 285 | /* If we have no profile at all, use AVG_LOOP_NITER iterations. */ |
97c53806 | 286 | if (!freq_latch) |
4661839e | 287 | expected = PARAM_VALUE (PARAM_AVG_LOOP_NITER); |
97c53806 JH |
288 | else |
289 | expected = freq_latch * 2; | |
290 | } | |
291 | else | |
292 | expected = (freq_latch + freq_in - 1) / freq_in; | |
3d436d2a | 293 | } |
97c53806 JH |
294 | |
295 | HOST_WIDE_INT max = get_max_loop_iterations_int (loop); | |
296 | if (max != -1 && max < expected) | |
297 | return max; | |
298 | return expected; | |
3d436d2a | 299 | } |
689ba89d | 300 | |
ac84e05e ZD |
301 | /* Returns expected number of LOOP iterations. The returned value is bounded |
302 | by REG_BR_PROB_BASE. */ | |
303 | ||
304 | unsigned | |
97c53806 | 305 | expected_loop_iterations (struct loop *loop) |
ac84e05e ZD |
306 | { |
307 | gcov_type expected = expected_loop_iterations_unbounded (loop); | |
308 | return (expected > REG_BR_PROB_BASE ? REG_BR_PROB_BASE : expected); | |
309 | } | |
310 | ||
689ba89d ZD |
311 | /* Returns the maximum level of nesting of subloops of LOOP. */ |
312 | ||
313 | unsigned | |
314 | get_loop_level (const struct loop *loop) | |
315 | { | |
316 | const struct loop *ploop; | |
317 | unsigned mx = 0, l; | |
318 | ||
319 | for (ploop = loop->inner; ploop; ploop = ploop->next) | |
320 | { | |
321 | l = get_loop_level (ploop); | |
322 | if (l >= mx) | |
323 | mx = l + 1; | |
324 | } | |
325 | return mx; | |
326 | } | |
5e962776 | 327 | |
5e962776 ZD |
328 | /* Initialize the constants for computing set costs. */ |
329 | ||
330 | void | |
331 | init_set_costs (void) | |
332 | { | |
f40751dd | 333 | int speed; |
1f75b71e | 334 | rtx_insn *seq; |
c3dc5e66 RS |
335 | rtx reg1 = gen_raw_REG (SImode, LAST_VIRTUAL_REGISTER + 1); |
336 | rtx reg2 = gen_raw_REG (SImode, LAST_VIRTUAL_REGISTER + 2); | |
337 | rtx addr = gen_raw_REG (Pmode, LAST_VIRTUAL_REGISTER + 3); | |
5e962776 ZD |
338 | rtx mem = validize_mem (gen_rtx_MEM (SImode, addr)); |
339 | unsigned i; | |
340 | ||
b5deb7b6 | 341 | target_avail_regs = 0; |
bec922f0 | 342 | target_clobbered_regs = 0; |
5e962776 ZD |
343 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) |
344 | if (TEST_HARD_REG_BIT (reg_class_contents[GENERAL_REGS], i) | |
345 | && !fixed_regs[i]) | |
bec922f0 SL |
346 | { |
347 | target_avail_regs++; | |
348 | if (call_used_regs[i]) | |
349 | target_clobbered_regs++; | |
350 | } | |
5e962776 | 351 | |
8b11a64c | 352 | target_res_regs = 3; |
5e962776 | 353 | |
f40751dd JH |
354 | for (speed = 0; speed < 2; speed++) |
355 | { | |
356 | crtl->maybe_hot_insn_p = speed; | |
357 | /* Set up the costs for using extra registers: | |
358 | ||
359 | 1) If not many free registers remain, we should prefer having an | |
360 | additional move to decreasing the number of available registers. | |
361 | (TARGET_REG_COST). | |
362 | 2) If no registers are available, we need to spill, which may require | |
363 | storing the old value to memory and loading it back | |
364 | (TARGET_SPILL_COST). */ | |
365 | ||
366 | start_sequence (); | |
367 | emit_move_insn (reg1, reg2); | |
368 | seq = get_insns (); | |
369 | end_sequence (); | |
370 | target_reg_cost [speed] = seq_cost (seq, speed); | |
371 | ||
372 | start_sequence (); | |
373 | emit_move_insn (mem, reg1); | |
374 | emit_move_insn (reg2, mem); | |
375 | seq = get_insns (); | |
376 | end_sequence (); | |
377 | target_spill_cost [speed] = seq_cost (seq, speed); | |
378 | } | |
379 | default_rtl_profile (); | |
5e962776 ZD |
380 | } |
381 | ||
a154b43a ZD |
382 | /* Estimates cost of increased register pressure caused by making N_NEW new |
383 | registers live around the loop. N_OLD is the number of registers live | |
bec922f0 SL |
384 | around the loop. If CALL_P is true, also take into account that |
385 | call-used registers may be clobbered in the loop body, reducing the | |
386 | number of available registers before we spill. */ | |
5e962776 ZD |
387 | |
388 | unsigned | |
bec922f0 SL |
389 | estimate_reg_pressure_cost (unsigned n_new, unsigned n_old, bool speed, |
390 | bool call_p) | |
5e962776 | 391 | { |
058e97ec | 392 | unsigned cost; |
a154b43a | 393 | unsigned regs_needed = n_new + n_old; |
bec922f0 SL |
394 | unsigned available_regs = target_avail_regs; |
395 | ||
396 | /* If there is a call in the loop body, the call-clobbered registers | |
397 | are not available for loop invariants. */ | |
398 | if (call_p) | |
399 | available_regs = available_regs - target_clobbered_regs; | |
5e962776 | 400 | |
a154b43a ZD |
401 | /* If we have enough registers, we should use them and not restrict |
402 | the transformations unnecessarily. */ | |
bec922f0 | 403 | if (regs_needed + target_res_regs <= available_regs) |
a154b43a ZD |
404 | return 0; |
405 | ||
bec922f0 | 406 | if (regs_needed <= available_regs) |
058e97ec VM |
407 | /* If we are close to running out of registers, try to preserve |
408 | them. */ | |
f40751dd | 409 | cost = target_reg_cost [speed] * n_new; |
058e97ec VM |
410 | else |
411 | /* If we run out of registers, it is very expensive to add another | |
412 | one. */ | |
f40751dd | 413 | cost = target_spill_cost [speed] * n_new; |
058e97ec | 414 | |
2af2dbdc VM |
415 | if (optimize && (flag_ira_region == IRA_REGION_ALL |
416 | || flag_ira_region == IRA_REGION_MIXED) | |
0fc822d0 | 417 | && number_of_loops (cfun) <= (unsigned) IRA_MAX_LOOPS_NUM) |
058e97ec VM |
418 | /* IRA regional allocation deals with high register pressure |
419 | better. So decrease the cost (to do more accurate the cost | |
420 | calculation for IRA, we need to know how many registers lives | |
421 | through the loop transparently). */ | |
422 | cost /= 2; | |
423 | ||
424 | return cost; | |
5e962776 ZD |
425 | } |
426 | ||
d73be268 | 427 | /* Sets EDGE_LOOP_EXIT flag for all loop exits. */ |
70388d94 ZD |
428 | |
429 | void | |
d73be268 | 430 | mark_loop_exit_edges (void) |
70388d94 ZD |
431 | { |
432 | basic_block bb; | |
433 | edge e; | |
c22cacf3 | 434 | |
0fc822d0 | 435 | if (number_of_loops (cfun) <= 1) |
70388d94 ZD |
436 | return; |
437 | ||
11cd3bed | 438 | FOR_EACH_BB_FN (bb, cfun) |
70388d94 ZD |
439 | { |
440 | edge_iterator ei; | |
441 | ||
70388d94 ZD |
442 | FOR_EACH_EDGE (e, ei, bb->succs) |
443 | { | |
9ba025a2 | 444 | if (loop_outer (bb->loop_father) |
2ff3e325 | 445 | && loop_exit_edge_p (bb->loop_father, e)) |
70388d94 ZD |
446 | e->flags |= EDGE_LOOP_EXIT; |
447 | else | |
448 | e->flags &= ~EDGE_LOOP_EXIT; | |
449 | } | |
450 | } | |
451 | } | |
452 | ||
f9bf4777 JH |
453 | /* Return exit edge if loop has only one exit that is likely |
454 | to be executed on runtime (i.e. it is not EH or leading | |
455 | to noreturn call. */ | |
456 | ||
457 | edge | |
458 | single_likely_exit (struct loop *loop) | |
459 | { | |
460 | edge found = single_exit (loop); | |
9771b263 | 461 | vec<edge> exits; |
f9bf4777 JH |
462 | unsigned i; |
463 | edge ex; | |
464 | ||
465 | if (found) | |
466 | return found; | |
467 | exits = get_loop_exit_edges (loop); | |
9771b263 | 468 | FOR_EACH_VEC_ELT (exits, i, ex) |
f9bf4777 JH |
469 | { |
470 | if (ex->flags & (EDGE_EH | EDGE_ABNORMAL_CALL)) | |
471 | continue; | |
472 | /* The constant of 5 is set in a way so noreturn calls are | |
473 | ruled out by this test. The static branch prediction algorithm | |
474 | will not assign such a low probability to conditionals for usual | |
475 | reasons. */ | |
0a6a6ac9 | 476 | if (profile_status_for_fn (cfun) != PROFILE_ABSENT |
f9bf4777 JH |
477 | && ex->probability < 5 && !ex->count) |
478 | continue; | |
479 | if (!found) | |
480 | found = ex; | |
481 | else | |
482 | { | |
9771b263 | 483 | exits.release (); |
f9bf4777 JH |
484 | return NULL; |
485 | } | |
486 | } | |
9771b263 | 487 | exits.release (); |
f9bf4777 JH |
488 | return found; |
489 | } | |
519cac4a JH |
490 | |
491 | ||
492 | /* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs | |
493 | order against direction of edges from latch. Specially, if | |
494 | header != latch, latch is the 1-st block. */ | |
495 | ||
9771b263 | 496 | vec<basic_block> |
519cac4a JH |
497 | get_loop_hot_path (const struct loop *loop) |
498 | { | |
499 | basic_block bb = loop->header; | |
6e1aa848 | 500 | vec<basic_block> path = vNULL; |
519cac4a JH |
501 | bitmap visited = BITMAP_ALLOC (NULL); |
502 | ||
503 | while (true) | |
504 | { | |
505 | edge_iterator ei; | |
506 | edge e; | |
507 | edge best = NULL; | |
508 | ||
9771b263 | 509 | path.safe_push (bb); |
519cac4a JH |
510 | bitmap_set_bit (visited, bb->index); |
511 | FOR_EACH_EDGE (e, ei, bb->succs) | |
512 | if ((!best || e->probability > best->probability) | |
513 | && !loop_exit_edge_p (loop, e) | |
514 | && !bitmap_bit_p (visited, e->dest->index)) | |
515 | best = e; | |
516 | if (!best || best->dest == loop->header) | |
517 | break; | |
518 | bb = best->dest; | |
519 | } | |
520 | BITMAP_FREE (visited); | |
521 | return path; | |
522 | } |