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59423b59 | 1 | /* Branch prediction routines for the GNU compiler. |
3aea1f79 | 2 | Copyright (C) 2000-2014 Free Software Foundation, Inc. |
59423b59 | 3 | |
e6751e9a | 4 | This file is part of GCC. |
59423b59 | 5 | |
e6751e9a | 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 | |
8c4c00c1 | 8 | Software Foundation; either version 3, or (at your option) any later |
e6751e9a | 9 | version. |
59423b59 | 10 | |
e6751e9a | 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. | |
59423b59 | 15 | |
e6751e9a | 16 | You should have received a copy of the GNU General Public License |
8c4c00c1 | 17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
59423b59 | 19 | |
20 | /* References: | |
21 | ||
22 | [1] "Branch Prediction for Free" | |
23 | Ball and Larus; PLDI '93. | |
24 | [2] "Static Branch Frequency and Program Profile Analysis" | |
25 | Wu and Larus; MICRO-27. | |
26 | [3] "Corpus-based Static Branch Prediction" | |
04641143 | 27 | Calder, Grunwald, Lindsay, Martin, Mozer, and Zorn; PLDI '95. */ |
59423b59 | 28 | |
29 | ||
30 | #include "config.h" | |
31 | #include "system.h" | |
805e22b2 | 32 | #include "coretypes.h" |
33 | #include "tm.h" | |
59423b59 | 34 | #include "tree.h" |
9ed99284 | 35 | #include "calls.h" |
59423b59 | 36 | #include "rtl.h" |
37 | #include "tm_p.h" | |
d6cb6164 | 38 | #include "hard-reg-set.h" |
94ea8568 | 39 | #include "predict.h" |
40 | #include "vec.h" | |
a3020f2f | 41 | #include "hashtab.h" |
42 | #include "hash-set.h" | |
a3020f2f | 43 | #include "machmode.h" |
44 | #include "input.h" | |
59423b59 | 45 | #include "function.h" |
94ea8568 | 46 | #include "dominance.h" |
47 | #include "cfg.h" | |
48 | #include "cfganal.h" | |
49 | #include "basic-block.h" | |
50 | #include "insn-config.h" | |
51 | #include "regs.h" | |
52 | #include "flags.h" | |
886c1262 | 53 | #include "profile.h" |
59423b59 | 54 | #include "except.h" |
0b205f4c | 55 | #include "diagnostic-core.h" |
59423b59 | 56 | #include "recog.h" |
59423b59 | 57 | #include "expr.h" |
e9fb8a64 | 58 | #include "coverage.h" |
e9d7220b | 59 | #include "sreal.h" |
429fa7fa | 60 | #include "params.h" |
61 | #include "target.h" | |
862be747 | 62 | #include "cfgloop.h" |
06ecf488 | 63 | #include "hash-map.h" |
bc61cadb | 64 | #include "tree-ssa-alias.h" |
65 | #include "internal-fn.h" | |
66 | #include "gimple-expr.h" | |
67 | #include "is-a.h" | |
073c1fd5 | 68 | #include "gimple.h" |
dcf1a1ec | 69 | #include "gimple-iterator.h" |
073c1fd5 | 70 | #include "gimple-ssa.h" |
1140c305 | 71 | #include "plugin-api.h" |
72 | #include "ipa-ref.h" | |
073c1fd5 | 73 | #include "cgraph.h" |
74 | #include "tree-cfg.h" | |
75 | #include "tree-phinodes.h" | |
76 | #include "ssa-iterators.h" | |
05d9c18a | 77 | #include "tree-ssa-loop-niter.h" |
073c1fd5 | 78 | #include "tree-ssa-loop.h" |
4ee9c684 | 79 | #include "tree-pass.h" |
d27b0b64 | 80 | #include "tree-scalar-evolution.h" |
81 | #include "cfgloop.h" | |
56ff4880 | 82 | |
2e3c56e8 | 83 | /* real constants: 0, 1, 1-1/REG_BR_PROB_BASE, REG_BR_PROB_BASE, |
84 | 1/REG_BR_PROB_BASE, 0.5, BB_FREQ_MAX. */ | |
e9d7220b | 85 | static sreal real_zero, real_one, real_almost_one, real_br_prob_base, |
86 | real_inv_br_prob_base, real_one_half, real_bb_freq_max; | |
59423b59 | 87 | |
ee5f6585 | 88 | static void combine_predictions_for_insn (rtx_insn *, basic_block); |
4ee9c684 | 89 | static void dump_prediction (FILE *, enum br_predictor, int, basic_block, int); |
d704ea82 | 90 | static void predict_paths_leading_to (basic_block, enum br_predictor, enum prediction); |
5707768a | 91 | static void predict_paths_leading_to_edge (edge, enum br_predictor, enum prediction); |
ee5f6585 | 92 | static bool can_predict_insn_p (const rtx_insn *); |
5e96f51e | 93 | |
13488c51 | 94 | /* Information we hold about each branch predictor. |
95 | Filled using information from predict.def. */ | |
e6751e9a | 96 | |
13488c51 | 97 | struct predictor_info |
5e96f51e | 98 | { |
e99c3a1d | 99 | const char *const name; /* Name used in the debugging dumps. */ |
100 | const int hitrate; /* Expected hitrate used by | |
101 | predict_insn_def call. */ | |
102 | const int flags; | |
13488c51 | 103 | }; |
5e96f51e | 104 | |
eb429644 | 105 | /* Use given predictor without Dempster-Shaffer theory if it matches |
106 | using first_match heuristics. */ | |
107 | #define PRED_FLAG_FIRST_MATCH 1 | |
108 | ||
109 | /* Recompute hitrate in percent to our representation. */ | |
110 | ||
e6751e9a | 111 | #define HITRATE(VAL) ((int) ((VAL) * REG_BR_PROB_BASE + 50) / 100) |
eb429644 | 112 | |
113 | #define DEF_PREDICTOR(ENUM, NAME, HITRATE, FLAGS) {NAME, HITRATE, FLAGS}, | |
e6751e9a | 114 | static const struct predictor_info predictor_info[]= { |
13488c51 | 115 | #include "predict.def" |
116 | ||
aa40f561 | 117 | /* Upper bound on predictors. */ |
eb429644 | 118 | {NULL, 0, 0} |
13488c51 | 119 | }; |
120 | #undef DEF_PREDICTOR | |
429fa7fa | 121 | |
eb7df8c2 | 122 | /* Return TRUE if frequency FREQ is considered to be hot. */ |
f29b326e | 123 | |
124 | static inline bool | |
8d672d12 | 125 | maybe_hot_frequency_p (struct function *fun, int freq) |
eb7df8c2 | 126 | { |
415d1b9a | 127 | struct cgraph_node *node = cgraph_node::get (fun->decl); |
69ad6a32 | 128 | if (!profile_info |
129 | || !opt_for_fn (fun->decl, flag_branch_probabilities)) | |
eb7df8c2 | 130 | { |
125b6d78 | 131 | if (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED) |
eb7df8c2 | 132 | return false; |
125b6d78 | 133 | if (node->frequency == NODE_FREQUENCY_HOT) |
eb7df8c2 | 134 | return true; |
135 | } | |
3bedbae3 | 136 | if (profile_status_for_fn (fun) == PROFILE_ABSENT) |
aa5f4f32 | 137 | return true; |
125b6d78 | 138 | if (node->frequency == NODE_FREQUENCY_EXECUTED_ONCE |
34154e27 | 139 | && freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency * 2 / 3)) |
125b6d78 | 140 | return false; |
6040d650 | 141 | if (PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) == 0) |
142 | return false; | |
34154e27 | 143 | if (freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency |
8d672d12 | 144 | / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))) |
eb7df8c2 | 145 | return false; |
146 | return true; | |
147 | } | |
148 | ||
9e179a64 | 149 | static gcov_type min_count = -1; |
150 | ||
151 | /* Determine the threshold for hot BB counts. */ | |
152 | ||
153 | gcov_type | |
154 | get_hot_bb_threshold () | |
155 | { | |
156 | gcov_working_set_t *ws; | |
157 | if (min_count == -1) | |
158 | { | |
159 | ws = find_working_set (PARAM_VALUE (HOT_BB_COUNT_WS_PERMILLE)); | |
160 | gcc_assert (ws); | |
161 | min_count = ws->min_counter; | |
162 | } | |
163 | return min_count; | |
164 | } | |
165 | ||
166 | /* Set the threshold for hot BB counts. */ | |
167 | ||
168 | void | |
169 | set_hot_bb_threshold (gcov_type min) | |
170 | { | |
171 | min_count = min; | |
172 | } | |
173 | ||
f29b326e | 174 | /* Return TRUE if frequency FREQ is considered to be hot. */ |
175 | ||
94bed7c3 | 176 | bool |
8d672d12 | 177 | maybe_hot_count_p (struct function *fun, gcov_type count) |
f29b326e | 178 | { |
3bedbae3 | 179 | if (fun && profile_status_for_fn (fun) != PROFILE_READ) |
f29b326e | 180 | return true; |
181 | /* Code executed at most once is not hot. */ | |
182 | if (profile_info->runs >= count) | |
183 | return false; | |
9e179a64 | 184 | return (count >= get_hot_bb_threshold ()); |
f29b326e | 185 | } |
186 | ||
429fa7fa | 187 | /* Return true in case BB can be CPU intensive and should be optimized |
41a6f238 | 188 | for maximal performance. */ |
429fa7fa | 189 | |
190 | bool | |
8d672d12 | 191 | maybe_hot_bb_p (struct function *fun, const_basic_block bb) |
429fa7fa | 192 | { |
8d672d12 | 193 | gcc_checking_assert (fun); |
3bedbae3 | 194 | if (profile_status_for_fn (fun) == PROFILE_READ) |
8d672d12 | 195 | return maybe_hot_count_p (fun, bb->count); |
196 | return maybe_hot_frequency_p (fun, bb->frequency); | |
eb7df8c2 | 197 | } |
198 | ||
199 | /* Return true in case BB can be CPU intensive and should be optimized | |
200 | for maximal performance. */ | |
201 | ||
202 | bool | |
203 | maybe_hot_edge_p (edge e) | |
204 | { | |
f26d8580 | 205 | if (profile_status_for_fn (cfun) == PROFILE_READ) |
8d672d12 | 206 | return maybe_hot_count_p (cfun, e->count); |
207 | return maybe_hot_frequency_p (cfun, EDGE_FREQUENCY (e)); | |
429fa7fa | 208 | } |
209 | ||
dcc9b351 | 210 | /* Return true if profile COUNT and FREQUENCY, or function FUN static |
211 | node frequency reflects never being executed. */ | |
212 | ||
213 | static bool | |
214 | probably_never_executed (struct function *fun, | |
215 | gcov_type count, int frequency) | |
429fa7fa | 216 | { |
8d672d12 | 217 | gcc_checking_assert (fun); |
69ad6a32 | 218 | if (profile_status_for_fn (fun) == PROFILE_READ) |
4befb9f4 | 219 | { |
c1acf60c | 220 | int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); |
221 | if (count * unlikely_count_fraction >= profile_info->runs) | |
4befb9f4 | 222 | return false; |
dcc9b351 | 223 | if (!frequency) |
4befb9f4 | 224 | return true; |
69ad6a32 | 225 | if (!ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency) |
4befb9f4 | 226 | return false; |
69ad6a32 | 227 | if (ENTRY_BLOCK_PTR_FOR_FN (fun)->count) |
4befb9f4 | 228 | { |
c1acf60c | 229 | gcov_type computed_count; |
230 | /* Check for possibility of overflow, in which case entry bb count | |
231 | is large enough to do the division first without losing much | |
232 | precision. */ | |
69ad6a32 | 233 | if (ENTRY_BLOCK_PTR_FOR_FN (fun)->count < REG_BR_PROB_BASE * |
34154e27 | 234 | REG_BR_PROB_BASE) |
c1acf60c | 235 | { |
236 | gcov_type scaled_count | |
69ad6a32 | 237 | = frequency * ENTRY_BLOCK_PTR_FOR_FN (fun)->count * |
34154e27 | 238 | unlikely_count_fraction; |
239 | computed_count = RDIV (scaled_count, | |
69ad6a32 | 240 | ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency); |
c1acf60c | 241 | } |
242 | else | |
243 | { | |
69ad6a32 | 244 | computed_count = RDIV (ENTRY_BLOCK_PTR_FOR_FN (fun)->count, |
245 | ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency); | |
c1acf60c | 246 | computed_count *= frequency * unlikely_count_fraction; |
247 | } | |
248 | if (computed_count >= profile_info->runs) | |
249 | return false; | |
4befb9f4 | 250 | } |
251 | return true; | |
252 | } | |
69ad6a32 | 253 | if ((!profile_info || !(opt_for_fn (fun->decl, flag_branch_probabilities))) |
415d1b9a | 254 | && (cgraph_node::get (fun->decl)->frequency |
fd6a3c41 | 255 | == NODE_FREQUENCY_UNLIKELY_EXECUTED)) |
5de92639 | 256 | return true; |
429fa7fa | 257 | return false; |
258 | } | |
259 | ||
80adc5a6 | 260 | |
dcc9b351 | 261 | /* Return true in case BB is probably never executed. */ |
262 | ||
263 | bool | |
264 | probably_never_executed_bb_p (struct function *fun, const_basic_block bb) | |
265 | { | |
266 | return probably_never_executed (fun, bb->count, bb->frequency); | |
267 | } | |
268 | ||
269 | ||
80adc5a6 | 270 | /* Return true in case edge E is probably never executed. */ |
271 | ||
272 | bool | |
273 | probably_never_executed_edge_p (struct function *fun, edge e) | |
429fa7fa | 274 | { |
dcc9b351 | 275 | return probably_never_executed (fun, e->count, EDGE_FREQUENCY (e)); |
429fa7fa | 276 | } |
277 | ||
cf262be9 | 278 | /* Return true when current function should always be optimized for size. */ |
279 | ||
280 | bool | |
281 | optimize_function_for_size_p (struct function *fun) | |
282 | { | |
cf262be9 | 283 | if (!fun || !fun->decl) |
69ad6a32 | 284 | return optimize_size; |
415d1b9a | 285 | cgraph_node *n = cgraph_node::get (fun->decl); |
286 | return n && n->optimize_for_size_p (); | |
cf262be9 | 287 | } |
288 | ||
533af0db | 289 | /* Return true when current function should always be optimized for speed. */ |
290 | ||
291 | bool | |
292 | optimize_function_for_speed_p (struct function *fun) | |
293 | { | |
294 | return !optimize_function_for_size_p (fun); | |
7dfb44a0 | 295 | } |
296 | ||
297 | /* Return TRUE when BB should be optimized for size. */ | |
298 | ||
299 | bool | |
94ba1cf1 | 300 | optimize_bb_for_size_p (const_basic_block bb) |
7dfb44a0 | 301 | { |
b9ea678c | 302 | return (optimize_function_for_size_p (cfun) |
303 | || (bb && !maybe_hot_bb_p (cfun, bb))); | |
7dfb44a0 | 304 | } |
305 | ||
306 | /* Return TRUE when BB should be optimized for speed. */ | |
307 | ||
308 | bool | |
94ba1cf1 | 309 | optimize_bb_for_speed_p (const_basic_block bb) |
7dfb44a0 | 310 | { |
311 | return !optimize_bb_for_size_p (bb); | |
312 | } | |
313 | ||
314 | /* Return TRUE when BB should be optimized for size. */ | |
315 | ||
316 | bool | |
317 | optimize_edge_for_size_p (edge e) | |
318 | { | |
533af0db | 319 | return optimize_function_for_size_p (cfun) || !maybe_hot_edge_p (e); |
7dfb44a0 | 320 | } |
321 | ||
322 | /* Return TRUE when BB should be optimized for speed. */ | |
323 | ||
324 | bool | |
325 | optimize_edge_for_speed_p (edge e) | |
326 | { | |
327 | return !optimize_edge_for_size_p (e); | |
328 | } | |
329 | ||
330 | /* Return TRUE when BB should be optimized for size. */ | |
331 | ||
332 | bool | |
333 | optimize_insn_for_size_p (void) | |
334 | { | |
533af0db | 335 | return optimize_function_for_size_p (cfun) || !crtl->maybe_hot_insn_p; |
7dfb44a0 | 336 | } |
337 | ||
338 | /* Return TRUE when BB should be optimized for speed. */ | |
339 | ||
340 | bool | |
341 | optimize_insn_for_speed_p (void) | |
342 | { | |
343 | return !optimize_insn_for_size_p (); | |
344 | } | |
345 | ||
94ba1cf1 | 346 | /* Return TRUE when LOOP should be optimized for size. */ |
347 | ||
348 | bool | |
349 | optimize_loop_for_size_p (struct loop *loop) | |
350 | { | |
351 | return optimize_bb_for_size_p (loop->header); | |
352 | } | |
353 | ||
354 | /* Return TRUE when LOOP should be optimized for speed. */ | |
355 | ||
356 | bool | |
357 | optimize_loop_for_speed_p (struct loop *loop) | |
358 | { | |
359 | return optimize_bb_for_speed_p (loop->header); | |
360 | } | |
361 | ||
0bfd8d5c | 362 | /* Return TRUE when LOOP nest should be optimized for speed. */ |
363 | ||
364 | bool | |
365 | optimize_loop_nest_for_speed_p (struct loop *loop) | |
366 | { | |
367 | struct loop *l = loop; | |
368 | if (optimize_loop_for_speed_p (loop)) | |
369 | return true; | |
370 | l = loop->inner; | |
53be41ae | 371 | while (l && l != loop) |
0bfd8d5c | 372 | { |
373 | if (optimize_loop_for_speed_p (l)) | |
374 | return true; | |
375 | if (l->inner) | |
376 | l = l->inner; | |
377 | else if (l->next) | |
378 | l = l->next; | |
379 | else | |
7baffbd3 | 380 | { |
381 | while (l != loop && !l->next) | |
382 | l = loop_outer (l); | |
383 | if (l != loop) | |
384 | l = l->next; | |
385 | } | |
0bfd8d5c | 386 | } |
387 | return false; | |
388 | } | |
389 | ||
390 | /* Return TRUE when LOOP nest should be optimized for size. */ | |
391 | ||
392 | bool | |
393 | optimize_loop_nest_for_size_p (struct loop *loop) | |
394 | { | |
395 | return !optimize_loop_nest_for_speed_p (loop); | |
396 | } | |
397 | ||
4a9d7ef7 | 398 | /* Return true when edge E is likely to be well predictable by branch |
399 | predictor. */ | |
400 | ||
401 | bool | |
402 | predictable_edge_p (edge e) | |
403 | { | |
f26d8580 | 404 | if (profile_status_for_fn (cfun) == PROFILE_ABSENT) |
4a9d7ef7 | 405 | return false; |
406 | if ((e->probability | |
407 | <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100) | |
408 | || (REG_BR_PROB_BASE - e->probability | |
409 | <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100)) | |
410 | return true; | |
411 | return false; | |
412 | } | |
413 | ||
414 | ||
7dfb44a0 | 415 | /* Set RTL expansion for BB profile. */ |
416 | ||
417 | void | |
418 | rtl_profile_for_bb (basic_block bb) | |
419 | { | |
8d672d12 | 420 | crtl->maybe_hot_insn_p = maybe_hot_bb_p (cfun, bb); |
7dfb44a0 | 421 | } |
422 | ||
423 | /* Set RTL expansion for edge profile. */ | |
424 | ||
425 | void | |
426 | rtl_profile_for_edge (edge e) | |
427 | { | |
428 | crtl->maybe_hot_insn_p = maybe_hot_edge_p (e); | |
429 | } | |
430 | ||
431 | /* Set RTL expansion to default mode (i.e. when profile info is not known). */ | |
432 | void | |
433 | default_rtl_profile (void) | |
434 | { | |
435 | crtl->maybe_hot_insn_p = true; | |
436 | } | |
437 | ||
cd0fe062 | 438 | /* Return true if the one of outgoing edges is already predicted by |
439 | PREDICTOR. */ | |
440 | ||
4ee9c684 | 441 | bool |
5493cb9a | 442 | rtl_predicted_by_p (const_basic_block bb, enum br_predictor predictor) |
cd0fe062 | 443 | { |
444 | rtx note; | |
5496dbfc | 445 | if (!INSN_P (BB_END (bb))) |
cd0fe062 | 446 | return false; |
5496dbfc | 447 | for (note = REG_NOTES (BB_END (bb)); note; note = XEXP (note, 1)) |
cd0fe062 | 448 | if (REG_NOTE_KIND (note) == REG_BR_PRED |
449 | && INTVAL (XEXP (XEXP (note, 0), 0)) == (int)predictor) | |
450 | return true; | |
451 | return false; | |
452 | } | |
5e96f51e | 453 | |
eeb030c4 | 454 | /* Structure representing predictions in tree level. */ |
455 | ||
456 | struct edge_prediction { | |
457 | struct edge_prediction *ep_next; | |
458 | edge ep_edge; | |
459 | enum br_predictor ep_predictor; | |
460 | int ep_probability; | |
461 | }; | |
462 | ||
06ecf488 | 463 | /* This map contains for a basic block the list of predictions for the |
464 | outgoing edges. */ | |
465 | ||
466 | static hash_map<const_basic_block, edge_prediction *> *bb_predictions; | |
467 | ||
4ee9c684 | 468 | /* Return true if the one of outgoing edges is already predicted by |
469 | PREDICTOR. */ | |
470 | ||
471 | bool | |
75a70cf9 | 472 | gimple_predicted_by_p (const_basic_block bb, enum br_predictor predictor) |
4ee9c684 | 473 | { |
7ea47fbd | 474 | struct edge_prediction *i; |
06ecf488 | 475 | edge_prediction **preds = bb_predictions->get (bb); |
b3723726 | 476 | |
477 | if (!preds) | |
478 | return false; | |
48e1416a | 479 | |
06ecf488 | 480 | for (i = *preds; i; i = i->ep_next) |
f45e9182 | 481 | if (i->ep_predictor == predictor) |
4ee9c684 | 482 | return true; |
483 | return false; | |
484 | } | |
485 | ||
b41438e5 | 486 | /* Return true when the probability of edge is reliable. |
48e1416a | 487 | |
b41438e5 | 488 | The profile guessing code is good at predicting branch outcome (ie. |
489 | taken/not taken), that is predicted right slightly over 75% of time. | |
ab4f0a13 | 490 | It is however notoriously poor on predicting the probability itself. |
b41438e5 | 491 | In general the profile appear a lot flatter (with probabilities closer |
492 | to 50%) than the reality so it is bad idea to use it to drive optimization | |
493 | such as those disabling dynamic branch prediction for well predictable | |
494 | branches. | |
495 | ||
496 | There are two exceptions - edges leading to noreturn edges and edges | |
497 | predicted by number of iterations heuristics are predicted well. This macro | |
498 | should be able to distinguish those, but at the moment it simply check for | |
499 | noreturn heuristic that is only one giving probability over 99% or bellow | |
ab4f0a13 | 500 | 1%. In future we might want to propagate reliability information across the |
b41438e5 | 501 | CFG if we find this information useful on multiple places. */ |
502 | static bool | |
503 | probability_reliable_p (int prob) | |
504 | { | |
f26d8580 | 505 | return (profile_status_for_fn (cfun) == PROFILE_READ |
506 | || (profile_status_for_fn (cfun) == PROFILE_GUESSED | |
b41438e5 | 507 | && (prob <= HITRATE (1) || prob >= HITRATE (99)))); |
508 | } | |
509 | ||
510 | /* Same predicate as above, working on edges. */ | |
511 | bool | |
7ecb5bb2 | 512 | edge_probability_reliable_p (const_edge e) |
b41438e5 | 513 | { |
514 | return probability_reliable_p (e->probability); | |
515 | } | |
516 | ||
517 | /* Same predicate as edge_probability_reliable_p, working on notes. */ | |
518 | bool | |
7ecb5bb2 | 519 | br_prob_note_reliable_p (const_rtx note) |
b41438e5 | 520 | { |
521 | gcc_assert (REG_NOTE_KIND (note) == REG_BR_PROB); | |
9eb946de | 522 | return probability_reliable_p (XINT (note, 0)); |
b41438e5 | 523 | } |
524 | ||
aa157ca4 | 525 | static void |
ee5f6585 | 526 | predict_insn (rtx_insn *insn, enum br_predictor predictor, int probability) |
13488c51 | 527 | { |
876760f6 | 528 | gcc_assert (any_condjump_p (insn)); |
b28bedce | 529 | if (!flag_guess_branch_prob) |
530 | return; | |
e6751e9a | 531 | |
a1ddb869 | 532 | add_reg_note (insn, REG_BR_PRED, |
533 | gen_rtx_CONCAT (VOIDmode, | |
534 | GEN_INT ((int) predictor), | |
535 | GEN_INT ((int) probability))); | |
13488c51 | 536 | } |
537 | ||
538 | /* Predict insn by given predictor. */ | |
e6751e9a | 539 | |
13488c51 | 540 | void |
ee5f6585 | 541 | predict_insn_def (rtx_insn *insn, enum br_predictor predictor, |
d598ad0d | 542 | enum prediction taken) |
13488c51 | 543 | { |
544 | int probability = predictor_info[(int) predictor].hitrate; | |
e6751e9a | 545 | |
13488c51 | 546 | if (taken != TAKEN) |
547 | probability = REG_BR_PROB_BASE - probability; | |
e6751e9a | 548 | |
13488c51 | 549 | predict_insn (insn, predictor, probability); |
5e96f51e | 550 | } |
551 | ||
552 | /* Predict edge E with given probability if possible. */ | |
e6751e9a | 553 | |
13488c51 | 554 | void |
4ee9c684 | 555 | rtl_predict_edge (edge e, enum br_predictor predictor, int probability) |
5e96f51e | 556 | { |
ee5f6585 | 557 | rtx_insn *last_insn; |
5496dbfc | 558 | last_insn = BB_END (e->src); |
5e96f51e | 559 | |
560 | /* We can store the branch prediction information only about | |
561 | conditional jumps. */ | |
562 | if (!any_condjump_p (last_insn)) | |
563 | return; | |
564 | ||
565 | /* We always store probability of branching. */ | |
566 | if (e->flags & EDGE_FALLTHRU) | |
567 | probability = REG_BR_PROB_BASE - probability; | |
568 | ||
13488c51 | 569 | predict_insn (last_insn, predictor, probability); |
570 | } | |
571 | ||
4ee9c684 | 572 | /* Predict edge E with the given PROBABILITY. */ |
573 | void | |
75a70cf9 | 574 | gimple_predict_edge (edge e, enum br_predictor predictor, int probability) |
4ee9c684 | 575 | { |
f26d8580 | 576 | gcc_assert (profile_status_for_fn (cfun) != PROFILE_GUESSED); |
34154e27 | 577 | if ((e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun) && EDGE_COUNT (e->src->succs) > |
578 | 1) | |
d5043f32 | 579 | && flag_guess_branch_prob && optimize) |
ebd65d12 | 580 | { |
b3723726 | 581 | struct edge_prediction *i = XNEW (struct edge_prediction); |
06ecf488 | 582 | edge_prediction *&preds = bb_predictions->get_or_insert (e->src); |
4ee9c684 | 583 | |
06ecf488 | 584 | i->ep_next = preds; |
585 | preds = i; | |
f45e9182 | 586 | i->ep_probability = probability; |
587 | i->ep_predictor = predictor; | |
588 | i->ep_edge = e; | |
ebd65d12 | 589 | } |
4ee9c684 | 590 | } |
591 | ||
631fa7de | 592 | /* Remove all predictions on given basic block that are attached |
593 | to edge E. */ | |
594 | void | |
595 | remove_predictions_associated_with_edge (edge e) | |
596 | { | |
b3723726 | 597 | if (!bb_predictions) |
598 | return; | |
599 | ||
06ecf488 | 600 | edge_prediction **preds = bb_predictions->get (e->src); |
b3723726 | 601 | |
602 | if (preds) | |
631fa7de | 603 | { |
06ecf488 | 604 | struct edge_prediction **prediction = preds; |
b3723726 | 605 | struct edge_prediction *next; |
606 | ||
631fa7de | 607 | while (*prediction) |
608 | { | |
f45e9182 | 609 | if ((*prediction)->ep_edge == e) |
b3723726 | 610 | { |
611 | next = (*prediction)->ep_next; | |
612 | free (*prediction); | |
613 | *prediction = next; | |
614 | } | |
631fa7de | 615 | else |
f45e9182 | 616 | prediction = &((*prediction)->ep_next); |
631fa7de | 617 | } |
618 | } | |
619 | } | |
620 | ||
b3723726 | 621 | /* Clears the list of predictions stored for BB. */ |
622 | ||
623 | static void | |
624 | clear_bb_predictions (basic_block bb) | |
625 | { | |
06ecf488 | 626 | edge_prediction **preds = bb_predictions->get (bb); |
b3723726 | 627 | struct edge_prediction *pred, *next; |
628 | ||
629 | if (!preds) | |
630 | return; | |
631 | ||
06ecf488 | 632 | for (pred = *preds; pred; pred = next) |
b3723726 | 633 | { |
634 | next = pred->ep_next; | |
635 | free (pred); | |
636 | } | |
637 | *preds = NULL; | |
638 | } | |
639 | ||
1a12dac4 | 640 | /* Return true when we can store prediction on insn INSN. |
641 | At the moment we represent predictions only on conditional | |
642 | jumps, not at computed jump or other complicated cases. */ | |
643 | static bool | |
ee5f6585 | 644 | can_predict_insn_p (const rtx_insn *insn) |
1a12dac4 | 645 | { |
6d7dc5b9 | 646 | return (JUMP_P (insn) |
1a12dac4 | 647 | && any_condjump_p (insn) |
cd665a06 | 648 | && EDGE_COUNT (BLOCK_FOR_INSN (insn)->succs) >= 2); |
1a12dac4 | 649 | } |
650 | ||
13488c51 | 651 | /* Predict edge E by given predictor if possible. */ |
e6751e9a | 652 | |
13488c51 | 653 | void |
d598ad0d | 654 | predict_edge_def (edge e, enum br_predictor predictor, |
655 | enum prediction taken) | |
13488c51 | 656 | { |
657 | int probability = predictor_info[(int) predictor].hitrate; | |
658 | ||
659 | if (taken != TAKEN) | |
660 | probability = REG_BR_PROB_BASE - probability; | |
e6751e9a | 661 | |
13488c51 | 662 | predict_edge (e, predictor, probability); |
663 | } | |
664 | ||
665 | /* Invert all branch predictions or probability notes in the INSN. This needs | |
666 | to be done each time we invert the condition used by the jump. */ | |
e6751e9a | 667 | |
13488c51 | 668 | void |
d598ad0d | 669 | invert_br_probabilities (rtx insn) |
13488c51 | 670 | { |
e6751e9a | 671 | rtx note; |
672 | ||
673 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) | |
674 | if (REG_NOTE_KIND (note) == REG_BR_PROB) | |
9eb946de | 675 | XINT (note, 0) = REG_BR_PROB_BASE - XINT (note, 0); |
e6751e9a | 676 | else if (REG_NOTE_KIND (note) == REG_BR_PRED) |
677 | XEXP (XEXP (note, 0), 1) | |
678 | = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (XEXP (note, 0), 1))); | |
13488c51 | 679 | } |
680 | ||
681 | /* Dump information about the branch prediction to the output file. */ | |
e6751e9a | 682 | |
13488c51 | 683 | static void |
4ee9c684 | 684 | dump_prediction (FILE *file, enum br_predictor predictor, int probability, |
d598ad0d | 685 | basic_block bb, int used) |
13488c51 | 686 | { |
cd665a06 | 687 | edge e; |
688 | edge_iterator ei; | |
13488c51 | 689 | |
4ee9c684 | 690 | if (!file) |
13488c51 | 691 | return; |
692 | ||
cd665a06 | 693 | FOR_EACH_EDGE (e, ei, bb->succs) |
694 | if (! (e->flags & EDGE_FALLTHRU)) | |
695 | break; | |
13488c51 | 696 | |
4ee9c684 | 697 | fprintf (file, " %s heuristics%s: %.1f%%", |
13488c51 | 698 | predictor_info[predictor].name, |
e6751e9a | 699 | used ? "" : " (ignored)", probability * 100.0 / REG_BR_PROB_BASE); |
13488c51 | 700 | |
701 | if (bb->count) | |
17a81216 | 702 | { |
3a4303e7 | 703 | fprintf (file, " exec %"PRId64, bb->count); |
12c94d25 | 704 | if (e) |
705 | { | |
3a4303e7 | 706 | fprintf (file, " hit %"PRId64, e->count); |
4ee9c684 | 707 | fprintf (file, " (%.1f%%)", e->count * 100.0 / bb->count); |
12c94d25 | 708 | } |
17a81216 | 709 | } |
e6751e9a | 710 | |
4ee9c684 | 711 | fprintf (file, "\n"); |
13488c51 | 712 | } |
713 | ||
7edd21a5 | 714 | /* We can not predict the probabilities of outgoing edges of bb. Set them |
83c8a977 | 715 | evenly and hope for the best. */ |
716 | static void | |
717 | set_even_probabilities (basic_block bb) | |
718 | { | |
719 | int nedges = 0; | |
720 | edge e; | |
cd665a06 | 721 | edge_iterator ei; |
83c8a977 | 722 | |
cd665a06 | 723 | FOR_EACH_EDGE (e, ei, bb->succs) |
83c8a977 | 724 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
725 | nedges ++; | |
cd665a06 | 726 | FOR_EACH_EDGE (e, ei, bb->succs) |
83c8a977 | 727 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
728 | e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges; | |
729 | else | |
730 | e->probability = 0; | |
731 | } | |
732 | ||
13488c51 | 733 | /* Combine all REG_BR_PRED notes into single probability and attach REG_BR_PROB |
734 | note if not already present. Remove now useless REG_BR_PRED notes. */ | |
e6751e9a | 735 | |
13488c51 | 736 | static void |
ee5f6585 | 737 | combine_predictions_for_insn (rtx_insn *insn, basic_block bb) |
13488c51 | 738 | { |
83c8a977 | 739 | rtx prob_note; |
740 | rtx *pnote; | |
e6751e9a | 741 | rtx note; |
13488c51 | 742 | int best_probability = PROB_EVEN; |
b9c74b4d | 743 | enum br_predictor best_predictor = END_PREDICTORS; |
eb429644 | 744 | int combined_probability = REG_BR_PROB_BASE / 2; |
745 | int d; | |
49d7c0db | 746 | bool first_match = false; |
747 | bool found = false; | |
13488c51 | 748 | |
83c8a977 | 749 | if (!can_predict_insn_p (insn)) |
750 | { | |
751 | set_even_probabilities (bb); | |
752 | return; | |
753 | } | |
754 | ||
755 | prob_note = find_reg_note (insn, REG_BR_PROB, 0); | |
756 | pnote = ®_NOTES (insn); | |
450d042a | 757 | if (dump_file) |
758 | fprintf (dump_file, "Predictions for insn %i bb %i\n", INSN_UID (insn), | |
b3d6de89 | 759 | bb->index); |
13488c51 | 760 | |
761 | /* We implement "first match" heuristics and use probability guessed | |
4ee9c684 | 762 | by predictor with smallest index. */ |
e6751e9a | 763 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) |
764 | if (REG_NOTE_KIND (note) == REG_BR_PRED) | |
765 | { | |
bc620c5c | 766 | enum br_predictor predictor = ((enum br_predictor) |
767 | INTVAL (XEXP (XEXP (note, 0), 0))); | |
e6751e9a | 768 | int probability = INTVAL (XEXP (XEXP (note, 0), 1)); |
769 | ||
770 | found = true; | |
771 | if (best_predictor > predictor) | |
772 | best_probability = probability, best_predictor = predictor; | |
773 | ||
774 | d = (combined_probability * probability | |
775 | + (REG_BR_PROB_BASE - combined_probability) | |
776 | * (REG_BR_PROB_BASE - probability)); | |
777 | ||
778 | /* Use FP math to avoid overflows of 32bit integers. */ | |
c4a616f2 | 779 | if (d == 0) |
780 | /* If one probability is 0% and one 100%, avoid division by zero. */ | |
781 | combined_probability = REG_BR_PROB_BASE / 2; | |
782 | else | |
783 | combined_probability = (((double) combined_probability) * probability | |
784 | * REG_BR_PROB_BASE / d + 0.5); | |
e6751e9a | 785 | } |
786 | ||
787 | /* Decide which heuristic to use. In case we didn't match anything, | |
788 | use no_prediction heuristic, in case we did match, use either | |
49d7c0db | 789 | first match or Dempster-Shaffer theory depending on the flags. */ |
790 | ||
eb429644 | 791 | if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH) |
49d7c0db | 792 | first_match = true; |
793 | ||
794 | if (!found) | |
4ee9c684 | 795 | dump_prediction (dump_file, PRED_NO_PREDICTION, |
796 | combined_probability, bb, true); | |
49d7c0db | 797 | else |
798 | { | |
4ee9c684 | 799 | dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, |
800 | bb, !first_match); | |
801 | dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, | |
802 | bb, first_match); | |
49d7c0db | 803 | } |
804 | ||
805 | if (first_match) | |
eb429644 | 806 | combined_probability = best_probability; |
4ee9c684 | 807 | dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); |
49d7c0db | 808 | |
809 | while (*pnote) | |
810 | { | |
811 | if (REG_NOTE_KIND (*pnote) == REG_BR_PRED) | |
812 | { | |
bc620c5c | 813 | enum br_predictor predictor = ((enum br_predictor) |
814 | INTVAL (XEXP (XEXP (*pnote, 0), 0))); | |
49d7c0db | 815 | int probability = INTVAL (XEXP (XEXP (*pnote, 0), 1)); |
816 | ||
4ee9c684 | 817 | dump_prediction (dump_file, predictor, probability, bb, |
49d7c0db | 818 | !first_match || best_predictor == predictor); |
195731ad | 819 | *pnote = XEXP (*pnote, 1); |
49d7c0db | 820 | } |
821 | else | |
195731ad | 822 | pnote = &XEXP (*pnote, 1); |
49d7c0db | 823 | } |
e6751e9a | 824 | |
13488c51 | 825 | if (!prob_note) |
826 | { | |
9eb946de | 827 | add_int_reg_note (insn, REG_BR_PROB, combined_probability); |
e6751e9a | 828 | |
eb429644 | 829 | /* Save the prediction into CFG in case we are seeing non-degenerated |
830 | conditional jump. */ | |
ea091dfd | 831 | if (!single_succ_p (bb)) |
eb429644 | 832 | { |
833 | BRANCH_EDGE (bb)->probability = combined_probability; | |
e6751e9a | 834 | FALLTHRU_EDGE (bb)->probability |
835 | = REG_BR_PROB_BASE - combined_probability; | |
eb429644 | 836 | } |
13488c51 | 837 | } |
ea091dfd | 838 | else if (!single_succ_p (bb)) |
d8c70625 | 839 | { |
9eb946de | 840 | int prob = XINT (prob_note, 0); |
d8c70625 | 841 | |
842 | BRANCH_EDGE (bb)->probability = prob; | |
843 | FALLTHRU_EDGE (bb)->probability = REG_BR_PROB_BASE - prob; | |
844 | } | |
845 | else | |
ea091dfd | 846 | single_succ_edge (bb)->probability = REG_BR_PROB_BASE; |
5e96f51e | 847 | } |
848 | ||
4ee9c684 | 849 | /* Combine predictions into single probability and store them into CFG. |
850 | Remove now useless prediction entries. */ | |
59423b59 | 851 | |
4ee9c684 | 852 | static void |
3f5be5f4 | 853 | combine_predictions_for_bb (basic_block bb) |
59423b59 | 854 | { |
4ee9c684 | 855 | int best_probability = PROB_EVEN; |
b9c74b4d | 856 | enum br_predictor best_predictor = END_PREDICTORS; |
4ee9c684 | 857 | int combined_probability = REG_BR_PROB_BASE / 2; |
858 | int d; | |
859 | bool first_match = false; | |
860 | bool found = false; | |
861 | struct edge_prediction *pred; | |
862 | int nedges = 0; | |
863 | edge e, first = NULL, second = NULL; | |
cd665a06 | 864 | edge_iterator ei; |
59423b59 | 865 | |
cd665a06 | 866 | FOR_EACH_EDGE (e, ei, bb->succs) |
4ee9c684 | 867 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
868 | { | |
cd665a06 | 869 | nedges ++; |
4ee9c684 | 870 | if (first && !second) |
871 | second = e; | |
872 | if (!first) | |
873 | first = e; | |
874 | } | |
875 | ||
48e1416a | 876 | /* When there is no successor or only one choice, prediction is easy. |
4ee9c684 | 877 | |
878 | We are lazy for now and predict only basic blocks with two outgoing | |
879 | edges. It is possible to predict generic case too, but we have to | |
880 | ignore first match heuristics and do more involved combining. Implement | |
881 | this later. */ | |
882 | if (nedges != 2) | |
883 | { | |
83c8a977 | 884 | if (!bb->count) |
885 | set_even_probabilities (bb); | |
b3723726 | 886 | clear_bb_predictions (bb); |
3f5be5f4 | 887 | if (dump_file) |
888 | fprintf (dump_file, "%i edges in bb %i predicted to even probabilities\n", | |
4ee9c684 | 889 | nedges, bb->index); |
890 | return; | |
891 | } | |
892 | ||
3f5be5f4 | 893 | if (dump_file) |
894 | fprintf (dump_file, "Predictions for bb %i\n", bb->index); | |
4ee9c684 | 895 | |
06ecf488 | 896 | edge_prediction **preds = bb_predictions->get (bb); |
b3723726 | 897 | if (preds) |
4ee9c684 | 898 | { |
b3723726 | 899 | /* We implement "first match" heuristics and use probability guessed |
900 | by predictor with smallest index. */ | |
06ecf488 | 901 | for (pred = *preds; pred; pred = pred->ep_next) |
b3723726 | 902 | { |
b9c74b4d | 903 | enum br_predictor predictor = pred->ep_predictor; |
b3723726 | 904 | int probability = pred->ep_probability; |
4ee9c684 | 905 | |
b3723726 | 906 | if (pred->ep_edge != first) |
907 | probability = REG_BR_PROB_BASE - probability; | |
4ee9c684 | 908 | |
b3723726 | 909 | found = true; |
9f694a82 | 910 | /* First match heuristics would be widly confused if we predicted |
911 | both directions. */ | |
b3723726 | 912 | if (best_predictor > predictor) |
9f694a82 | 913 | { |
914 | struct edge_prediction *pred2; | |
915 | int prob = probability; | |
916 | ||
c83059be | 917 | for (pred2 = (struct edge_prediction *) *preds; |
918 | pred2; pred2 = pred2->ep_next) | |
9f694a82 | 919 | if (pred2 != pred && pred2->ep_predictor == pred->ep_predictor) |
920 | { | |
921 | int probability2 = pred->ep_probability; | |
922 | ||
923 | if (pred2->ep_edge != first) | |
924 | probability2 = REG_BR_PROB_BASE - probability2; | |
925 | ||
48e1416a | 926 | if ((probability < REG_BR_PROB_BASE / 2) != |
9f694a82 | 927 | (probability2 < REG_BR_PROB_BASE / 2)) |
928 | break; | |
929 | ||
930 | /* If the same predictor later gave better result, go for it! */ | |
931 | if ((probability >= REG_BR_PROB_BASE / 2 && (probability2 > probability)) | |
932 | || (probability <= REG_BR_PROB_BASE / 2 && (probability2 < probability))) | |
933 | prob = probability2; | |
934 | } | |
935 | if (!pred2) | |
936 | best_probability = prob, best_predictor = predictor; | |
937 | } | |
4ee9c684 | 938 | |
b3723726 | 939 | d = (combined_probability * probability |
940 | + (REG_BR_PROB_BASE - combined_probability) | |
941 | * (REG_BR_PROB_BASE - probability)); | |
4ee9c684 | 942 | |
b3723726 | 943 | /* Use FP math to avoid overflows of 32bit integers. */ |
944 | if (d == 0) | |
945 | /* If one probability is 0% and one 100%, avoid division by zero. */ | |
946 | combined_probability = REG_BR_PROB_BASE / 2; | |
947 | else | |
948 | combined_probability = (((double) combined_probability) | |
949 | * probability | |
950 | * REG_BR_PROB_BASE / d + 0.5); | |
951 | } | |
4ee9c684 | 952 | } |
953 | ||
954 | /* Decide which heuristic to use. In case we didn't match anything, | |
955 | use no_prediction heuristic, in case we did match, use either | |
956 | first match or Dempster-Shaffer theory depending on the flags. */ | |
957 | ||
958 | if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH) | |
959 | first_match = true; | |
960 | ||
961 | if (!found) | |
3f5be5f4 | 962 | dump_prediction (dump_file, PRED_NO_PREDICTION, combined_probability, bb, true); |
4ee9c684 | 963 | else |
964 | { | |
3f5be5f4 | 965 | dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, bb, |
4ee9c684 | 966 | !first_match); |
3f5be5f4 | 967 | dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, bb, |
4ee9c684 | 968 | first_match); |
969 | } | |
970 | ||
971 | if (first_match) | |
972 | combined_probability = best_probability; | |
3f5be5f4 | 973 | dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); |
4ee9c684 | 974 | |
b3723726 | 975 | if (preds) |
4ee9c684 | 976 | { |
4077bf7a | 977 | for (pred = (struct edge_prediction *) *preds; pred; pred = pred->ep_next) |
b3723726 | 978 | { |
b9c74b4d | 979 | enum br_predictor predictor = pred->ep_predictor; |
b3723726 | 980 | int probability = pred->ep_probability; |
4ee9c684 | 981 | |
b3723726 | 982 | if (pred->ep_edge != EDGE_SUCC (bb, 0)) |
983 | probability = REG_BR_PROB_BASE - probability; | |
984 | dump_prediction (dump_file, predictor, probability, bb, | |
985 | !first_match || best_predictor == predictor); | |
986 | } | |
4ee9c684 | 987 | } |
b3723726 | 988 | clear_bb_predictions (bb); |
4ee9c684 | 989 | |
83c8a977 | 990 | if (!bb->count) |
991 | { | |
992 | first->probability = combined_probability; | |
993 | second->probability = REG_BR_PROB_BASE - combined_probability; | |
994 | } | |
4ee9c684 | 995 | } |
996 | ||
fd757b76 | 997 | /* Check if T1 and T2 satisfy the IV_COMPARE condition. |
998 | Return the SSA_NAME if the condition satisfies, NULL otherwise. | |
999 | ||
1000 | T1 and T2 should be one of the following cases: | |
1001 | 1. T1 is SSA_NAME, T2 is NULL | |
1002 | 2. T1 is SSA_NAME, T2 is INTEGER_CST between [-4, 4] | |
1003 | 3. T2 is SSA_NAME, T1 is INTEGER_CST between [-4, 4] */ | |
1004 | ||
1005 | static tree | |
1006 | strips_small_constant (tree t1, tree t2) | |
1007 | { | |
1008 | tree ret = NULL; | |
1009 | int value = 0; | |
1010 | ||
1011 | if (!t1) | |
1012 | return NULL; | |
1013 | else if (TREE_CODE (t1) == SSA_NAME) | |
1014 | ret = t1; | |
e913b5cd | 1015 | else if (tree_fits_shwi_p (t1)) |
1016 | value = tree_to_shwi (t1); | |
fd757b76 | 1017 | else |
1018 | return NULL; | |
1019 | ||
1020 | if (!t2) | |
1021 | return ret; | |
e913b5cd | 1022 | else if (tree_fits_shwi_p (t2)) |
1023 | value = tree_to_shwi (t2); | |
fd757b76 | 1024 | else if (TREE_CODE (t2) == SSA_NAME) |
1025 | { | |
1026 | if (ret) | |
1027 | return NULL; | |
1028 | else | |
1029 | ret = t2; | |
1030 | } | |
1031 | ||
1032 | if (value <= 4 && value >= -4) | |
1033 | return ret; | |
1034 | else | |
1035 | return NULL; | |
1036 | } | |
1037 | ||
1038 | /* Return the SSA_NAME in T or T's operands. | |
1039 | Return NULL if SSA_NAME cannot be found. */ | |
1040 | ||
1041 | static tree | |
1042 | get_base_value (tree t) | |
1043 | { | |
1044 | if (TREE_CODE (t) == SSA_NAME) | |
1045 | return t; | |
1046 | ||
1047 | if (!BINARY_CLASS_P (t)) | |
1048 | return NULL; | |
1049 | ||
1050 | switch (TREE_OPERAND_LENGTH (t)) | |
1051 | { | |
1052 | case 1: | |
1053 | return strips_small_constant (TREE_OPERAND (t, 0), NULL); | |
1054 | case 2: | |
1055 | return strips_small_constant (TREE_OPERAND (t, 0), | |
1056 | TREE_OPERAND (t, 1)); | |
1057 | default: | |
1058 | return NULL; | |
1059 | } | |
1060 | } | |
1061 | ||
1062 | /* Check the compare STMT in LOOP. If it compares an induction | |
1063 | variable to a loop invariant, return true, and save | |
1064 | LOOP_INVARIANT, COMPARE_CODE and LOOP_STEP. | |
1065 | Otherwise return false and set LOOP_INVAIANT to NULL. */ | |
1066 | ||
1067 | static bool | |
1a91d914 | 1068 | is_comparison_with_loop_invariant_p (gcond *stmt, struct loop *loop, |
fd757b76 | 1069 | tree *loop_invariant, |
1070 | enum tree_code *compare_code, | |
b3269f54 | 1071 | tree *loop_step, |
fd757b76 | 1072 | tree *loop_iv_base) |
1073 | { | |
1074 | tree op0, op1, bound, base; | |
1075 | affine_iv iv0, iv1; | |
1076 | enum tree_code code; | |
b3269f54 | 1077 | tree step; |
fd757b76 | 1078 | |
1079 | code = gimple_cond_code (stmt); | |
1080 | *loop_invariant = NULL; | |
1081 | ||
1082 | switch (code) | |
1083 | { | |
1084 | case GT_EXPR: | |
1085 | case GE_EXPR: | |
1086 | case NE_EXPR: | |
1087 | case LT_EXPR: | |
1088 | case LE_EXPR: | |
1089 | case EQ_EXPR: | |
1090 | break; | |
1091 | ||
1092 | default: | |
1093 | return false; | |
1094 | } | |
1095 | ||
1096 | op0 = gimple_cond_lhs (stmt); | |
1097 | op1 = gimple_cond_rhs (stmt); | |
1098 | ||
1099 | if ((TREE_CODE (op0) != SSA_NAME && TREE_CODE (op0) != INTEGER_CST) | |
1100 | || (TREE_CODE (op1) != SSA_NAME && TREE_CODE (op1) != INTEGER_CST)) | |
1101 | return false; | |
1102 | if (!simple_iv (loop, loop_containing_stmt (stmt), op0, &iv0, true)) | |
1103 | return false; | |
1104 | if (!simple_iv (loop, loop_containing_stmt (stmt), op1, &iv1, true)) | |
1105 | return false; | |
1106 | if (TREE_CODE (iv0.step) != INTEGER_CST | |
1107 | || TREE_CODE (iv1.step) != INTEGER_CST) | |
1108 | return false; | |
1109 | if ((integer_zerop (iv0.step) && integer_zerop (iv1.step)) | |
1110 | || (!integer_zerop (iv0.step) && !integer_zerop (iv1.step))) | |
1111 | return false; | |
1112 | ||
1113 | if (integer_zerop (iv0.step)) | |
1114 | { | |
1115 | if (code != NE_EXPR && code != EQ_EXPR) | |
1116 | code = invert_tree_comparison (code, false); | |
1117 | bound = iv0.base; | |
1118 | base = iv1.base; | |
e913b5cd | 1119 | if (tree_fits_shwi_p (iv1.step)) |
b3269f54 | 1120 | step = iv1.step; |
fd757b76 | 1121 | else |
1122 | return false; | |
1123 | } | |
1124 | else | |
1125 | { | |
1126 | bound = iv1.base; | |
1127 | base = iv0.base; | |
e913b5cd | 1128 | if (tree_fits_shwi_p (iv0.step)) |
b3269f54 | 1129 | step = iv0.step; |
fd757b76 | 1130 | else |
1131 | return false; | |
1132 | } | |
1133 | ||
1134 | if (TREE_CODE (bound) != INTEGER_CST) | |
1135 | bound = get_base_value (bound); | |
1136 | if (!bound) | |
1137 | return false; | |
1138 | if (TREE_CODE (base) != INTEGER_CST) | |
1139 | base = get_base_value (base); | |
1140 | if (!base) | |
1141 | return false; | |
1142 | ||
1143 | *loop_invariant = bound; | |
1144 | *compare_code = code; | |
1145 | *loop_step = step; | |
1146 | *loop_iv_base = base; | |
1147 | return true; | |
1148 | } | |
1149 | ||
1150 | /* Compare two SSA_NAMEs: returns TRUE if T1 and T2 are value coherent. */ | |
1151 | ||
1152 | static bool | |
1153 | expr_coherent_p (tree t1, tree t2) | |
1154 | { | |
1155 | gimple stmt; | |
1156 | tree ssa_name_1 = NULL; | |
1157 | tree ssa_name_2 = NULL; | |
1158 | ||
1159 | gcc_assert (TREE_CODE (t1) == SSA_NAME || TREE_CODE (t1) == INTEGER_CST); | |
1160 | gcc_assert (TREE_CODE (t2) == SSA_NAME || TREE_CODE (t2) == INTEGER_CST); | |
1161 | ||
1162 | if (t1 == t2) | |
1163 | return true; | |
1164 | ||
1165 | if (TREE_CODE (t1) == INTEGER_CST && TREE_CODE (t2) == INTEGER_CST) | |
1166 | return true; | |
1167 | if (TREE_CODE (t1) == INTEGER_CST || TREE_CODE (t2) == INTEGER_CST) | |
1168 | return false; | |
1169 | ||
1170 | /* Check to see if t1 is expressed/defined with t2. */ | |
1171 | stmt = SSA_NAME_DEF_STMT (t1); | |
1172 | gcc_assert (stmt != NULL); | |
1173 | if (is_gimple_assign (stmt)) | |
1174 | { | |
1175 | ssa_name_1 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); | |
1176 | if (ssa_name_1 && ssa_name_1 == t2) | |
1177 | return true; | |
1178 | } | |
1179 | ||
1180 | /* Check to see if t2 is expressed/defined with t1. */ | |
1181 | stmt = SSA_NAME_DEF_STMT (t2); | |
1182 | gcc_assert (stmt != NULL); | |
1183 | if (is_gimple_assign (stmt)) | |
1184 | { | |
1185 | ssa_name_2 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); | |
1186 | if (ssa_name_2 && ssa_name_2 == t1) | |
1187 | return true; | |
1188 | } | |
1189 | ||
1190 | /* Compare if t1 and t2's def_stmts are identical. */ | |
1191 | if (ssa_name_2 != NULL && ssa_name_1 == ssa_name_2) | |
1192 | return true; | |
1193 | else | |
1194 | return false; | |
1195 | } | |
1196 | ||
1197 | /* Predict branch probability of BB when BB contains a branch that compares | |
1198 | an induction variable in LOOP with LOOP_IV_BASE_VAR to LOOP_BOUND_VAR. The | |
1199 | loop exit is compared using LOOP_BOUND_CODE, with step of LOOP_BOUND_STEP. | |
1200 | ||
1201 | E.g. | |
1202 | for (int i = 0; i < bound; i++) { | |
1203 | if (i < bound - 2) | |
1204 | computation_1(); | |
1205 | else | |
1206 | computation_2(); | |
1207 | } | |
1208 | ||
1209 | In this loop, we will predict the branch inside the loop to be taken. */ | |
1210 | ||
1211 | static void | |
1212 | predict_iv_comparison (struct loop *loop, basic_block bb, | |
1213 | tree loop_bound_var, | |
1214 | tree loop_iv_base_var, | |
1215 | enum tree_code loop_bound_code, | |
1216 | int loop_bound_step) | |
1217 | { | |
1218 | gimple stmt; | |
1219 | tree compare_var, compare_base; | |
1220 | enum tree_code compare_code; | |
b3269f54 | 1221 | tree compare_step_var; |
fd757b76 | 1222 | edge then_edge; |
1223 | edge_iterator ei; | |
1224 | ||
1225 | if (predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED) | |
1226 | || predicted_by_p (bb, PRED_LOOP_ITERATIONS) | |
1227 | || predicted_by_p (bb, PRED_LOOP_EXIT)) | |
1228 | return; | |
1229 | ||
1230 | stmt = last_stmt (bb); | |
1231 | if (!stmt || gimple_code (stmt) != GIMPLE_COND) | |
1232 | return; | |
1a91d914 | 1233 | if (!is_comparison_with_loop_invariant_p (as_a <gcond *> (stmt), |
1234 | loop, &compare_var, | |
fd757b76 | 1235 | &compare_code, |
b3269f54 | 1236 | &compare_step_var, |
fd757b76 | 1237 | &compare_base)) |
1238 | return; | |
1239 | ||
1240 | /* Find the taken edge. */ | |
1241 | FOR_EACH_EDGE (then_edge, ei, bb->succs) | |
1242 | if (then_edge->flags & EDGE_TRUE_VALUE) | |
1243 | break; | |
1244 | ||
1245 | /* When comparing an IV to a loop invariant, NE is more likely to be | |
1246 | taken while EQ is more likely to be not-taken. */ | |
1247 | if (compare_code == NE_EXPR) | |
1248 | { | |
1249 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1250 | return; | |
1251 | } | |
1252 | else if (compare_code == EQ_EXPR) | |
1253 | { | |
1254 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1255 | return; | |
1256 | } | |
1257 | ||
1258 | if (!expr_coherent_p (loop_iv_base_var, compare_base)) | |
1259 | return; | |
1260 | ||
1261 | /* If loop bound, base and compare bound are all constants, we can | |
1262 | calculate the probability directly. */ | |
e913b5cd | 1263 | if (tree_fits_shwi_p (loop_bound_var) |
1264 | && tree_fits_shwi_p (compare_var) | |
1265 | && tree_fits_shwi_p (compare_base)) | |
fd757b76 | 1266 | { |
1267 | int probability; | |
e913b5cd | 1268 | bool overflow, overall_overflow = false; |
ab2c1de8 | 1269 | widest_int compare_count, tem; |
b3269f54 | 1270 | |
b3269f54 | 1271 | /* (loop_bound - base) / compare_step */ |
c311b856 | 1272 | tem = wi::sub (wi::to_widest (loop_bound_var), |
1273 | wi::to_widest (compare_base), SIGNED, &overflow); | |
e913b5cd | 1274 | overall_overflow |= overflow; |
c311b856 | 1275 | widest_int loop_count = wi::div_trunc (tem, |
1276 | wi::to_widest (compare_step_var), | |
1277 | SIGNED, &overflow); | |
e913b5cd | 1278 | overall_overflow |= overflow; |
1279 | ||
c311b856 | 1280 | if (!wi::neg_p (wi::to_widest (compare_step_var)) |
fd757b76 | 1281 | ^ (compare_code == LT_EXPR || compare_code == LE_EXPR)) |
b3269f54 | 1282 | { |
1283 | /* (loop_bound - compare_bound) / compare_step */ | |
c311b856 | 1284 | tem = wi::sub (wi::to_widest (loop_bound_var), |
1285 | wi::to_widest (compare_var), SIGNED, &overflow); | |
e913b5cd | 1286 | overall_overflow |= overflow; |
c311b856 | 1287 | compare_count = wi::div_trunc (tem, wi::to_widest (compare_step_var), |
1288 | SIGNED, &overflow); | |
e913b5cd | 1289 | overall_overflow |= overflow; |
b3269f54 | 1290 | } |
fd757b76 | 1291 | else |
b3269f54 | 1292 | { |
1293 | /* (compare_bound - base) / compare_step */ | |
c311b856 | 1294 | tem = wi::sub (wi::to_widest (compare_var), |
1295 | wi::to_widest (compare_base), SIGNED, &overflow); | |
e913b5cd | 1296 | overall_overflow |= overflow; |
c311b856 | 1297 | compare_count = wi::div_trunc (tem, wi::to_widest (compare_step_var), |
1298 | SIGNED, &overflow); | |
e913b5cd | 1299 | overall_overflow |= overflow; |
b3269f54 | 1300 | } |
fd757b76 | 1301 | if (compare_code == LE_EXPR || compare_code == GE_EXPR) |
b3269f54 | 1302 | ++compare_count; |
fd757b76 | 1303 | if (loop_bound_code == LE_EXPR || loop_bound_code == GE_EXPR) |
b3269f54 | 1304 | ++loop_count; |
796b6678 | 1305 | if (wi::neg_p (compare_count)) |
e913b5cd | 1306 | compare_count = 0; |
796b6678 | 1307 | if (wi::neg_p (loop_count)) |
e913b5cd | 1308 | loop_count = 0; |
796b6678 | 1309 | if (loop_count == 0) |
fd757b76 | 1310 | probability = 0; |
796b6678 | 1311 | else if (wi::cmps (compare_count, loop_count) == 1) |
fd757b76 | 1312 | probability = REG_BR_PROB_BASE; |
1313 | else | |
b3269f54 | 1314 | { |
e913b5cd | 1315 | tem = compare_count * REG_BR_PROB_BASE; |
796b6678 | 1316 | tem = wi::udiv_trunc (tem, loop_count); |
b3269f54 | 1317 | probability = tem.to_uhwi (); |
1318 | } | |
1319 | ||
e913b5cd | 1320 | if (!overall_overflow) |
b3269f54 | 1321 | predict_edge (then_edge, PRED_LOOP_IV_COMPARE, probability); |
1322 | ||
fd757b76 | 1323 | return; |
1324 | } | |
1325 | ||
1326 | if (expr_coherent_p (loop_bound_var, compare_var)) | |
1327 | { | |
1328 | if ((loop_bound_code == LT_EXPR || loop_bound_code == LE_EXPR) | |
1329 | && (compare_code == LT_EXPR || compare_code == LE_EXPR)) | |
1330 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1331 | else if ((loop_bound_code == GT_EXPR || loop_bound_code == GE_EXPR) | |
1332 | && (compare_code == GT_EXPR || compare_code == GE_EXPR)) | |
1333 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1334 | else if (loop_bound_code == NE_EXPR) | |
1335 | { | |
1336 | /* If the loop backedge condition is "(i != bound)", we do | |
1337 | the comparison based on the step of IV: | |
1338 | * step < 0 : backedge condition is like (i > bound) | |
1339 | * step > 0 : backedge condition is like (i < bound) */ | |
1340 | gcc_assert (loop_bound_step != 0); | |
1341 | if (loop_bound_step > 0 | |
1342 | && (compare_code == LT_EXPR | |
1343 | || compare_code == LE_EXPR)) | |
1344 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1345 | else if (loop_bound_step < 0 | |
1346 | && (compare_code == GT_EXPR | |
1347 | || compare_code == GE_EXPR)) | |
1348 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1349 | else | |
1350 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1351 | } | |
1352 | else | |
1353 | /* The branch is predicted not-taken if loop_bound_code is | |
1354 | opposite with compare_code. */ | |
1355 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1356 | } | |
1357 | else if (expr_coherent_p (loop_iv_base_var, compare_var)) | |
1358 | { | |
1359 | /* For cases like: | |
1360 | for (i = s; i < h; i++) | |
1361 | if (i > s + 2) .... | |
1362 | The branch should be predicted taken. */ | |
1363 | if (loop_bound_step > 0 | |
1364 | && (compare_code == GT_EXPR || compare_code == GE_EXPR)) | |
1365 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1366 | else if (loop_bound_step < 0 | |
1367 | && (compare_code == LT_EXPR || compare_code == LE_EXPR)) | |
1368 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1369 | else | |
1370 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1371 | } | |
1372 | } | |
4ca17abf | 1373 | |
1374 | /* Predict for extra loop exits that will lead to EXIT_EDGE. The extra loop | |
1375 | exits are resulted from short-circuit conditions that will generate an | |
1376 | if_tmp. E.g.: | |
1377 | ||
1378 | if (foo() || global > 10) | |
1379 | break; | |
1380 | ||
1381 | This will be translated into: | |
1382 | ||
1383 | BB3: | |
1384 | loop header... | |
1385 | BB4: | |
1386 | if foo() goto BB6 else goto BB5 | |
1387 | BB5: | |
1388 | if global > 10 goto BB6 else goto BB7 | |
1389 | BB6: | |
1390 | goto BB7 | |
1391 | BB7: | |
1392 | iftmp = (PHI 0(BB5), 1(BB6)) | |
1393 | if iftmp == 1 goto BB8 else goto BB3 | |
1394 | BB8: | |
1395 | outside of the loop... | |
1396 | ||
1397 | The edge BB7->BB8 is loop exit because BB8 is outside of the loop. | |
1398 | From the dataflow, we can infer that BB4->BB6 and BB5->BB6 are also loop | |
1399 | exits. This function takes BB7->BB8 as input, and finds out the extra loop | |
1400 | exits to predict them using PRED_LOOP_EXIT. */ | |
1401 | ||
1402 | static void | |
1403 | predict_extra_loop_exits (edge exit_edge) | |
1404 | { | |
1405 | unsigned i; | |
1406 | bool check_value_one; | |
1a91d914 | 1407 | gimple lhs_def_stmt; |
1408 | gphi *phi_stmt; | |
4ca17abf | 1409 | tree cmp_rhs, cmp_lhs; |
1a91d914 | 1410 | gimple last; |
1411 | gcond *cmp_stmt; | |
4ca17abf | 1412 | |
1a91d914 | 1413 | last = last_stmt (exit_edge->src); |
1414 | if (!last) | |
1415 | return; | |
1416 | cmp_stmt = dyn_cast <gcond *> (last); | |
1417 | if (!cmp_stmt) | |
4ca17abf | 1418 | return; |
1a91d914 | 1419 | |
4ca17abf | 1420 | cmp_rhs = gimple_cond_rhs (cmp_stmt); |
1421 | cmp_lhs = gimple_cond_lhs (cmp_stmt); | |
1422 | if (!TREE_CONSTANT (cmp_rhs) | |
1423 | || !(integer_zerop (cmp_rhs) || integer_onep (cmp_rhs))) | |
1424 | return; | |
1425 | if (TREE_CODE (cmp_lhs) != SSA_NAME) | |
1426 | return; | |
1427 | ||
1428 | /* If check_value_one is true, only the phi_args with value '1' will lead | |
1429 | to loop exit. Otherwise, only the phi_args with value '0' will lead to | |
1430 | loop exit. */ | |
1431 | check_value_one = (((integer_onep (cmp_rhs)) | |
1432 | ^ (gimple_cond_code (cmp_stmt) == EQ_EXPR)) | |
1433 | ^ ((exit_edge->flags & EDGE_TRUE_VALUE) != 0)); | |
1434 | ||
1a91d914 | 1435 | lhs_def_stmt = SSA_NAME_DEF_STMT (cmp_lhs); |
1436 | if (!lhs_def_stmt) | |
1437 | return; | |
1438 | ||
1439 | phi_stmt = dyn_cast <gphi *> (lhs_def_stmt); | |
1440 | if (!phi_stmt) | |
4ca17abf | 1441 | return; |
1442 | ||
1443 | for (i = 0; i < gimple_phi_num_args (phi_stmt); i++) | |
1444 | { | |
1445 | edge e1; | |
1446 | edge_iterator ei; | |
1447 | tree val = gimple_phi_arg_def (phi_stmt, i); | |
1448 | edge e = gimple_phi_arg_edge (phi_stmt, i); | |
1449 | ||
1450 | if (!TREE_CONSTANT (val) || !(integer_zerop (val) || integer_onep (val))) | |
1451 | continue; | |
1452 | if ((check_value_one ^ integer_onep (val)) == 1) | |
1453 | continue; | |
1454 | if (EDGE_COUNT (e->src->succs) != 1) | |
1455 | { | |
1456 | predict_paths_leading_to_edge (e, PRED_LOOP_EXIT, NOT_TAKEN); | |
1457 | continue; | |
1458 | } | |
1459 | ||
1460 | FOR_EACH_EDGE (e1, ei, e->src->preds) | |
1461 | predict_paths_leading_to_edge (e1, PRED_LOOP_EXIT, NOT_TAKEN); | |
1462 | } | |
1463 | } | |
1464 | ||
7194de72 | 1465 | /* Predict edge probabilities by exploiting loop structure. */ |
1466 | ||
4ee9c684 | 1467 | static void |
7194de72 | 1468 | predict_loops (void) |
4ee9c684 | 1469 | { |
17519ba0 | 1470 | struct loop *loop; |
c12f2fcb | 1471 | |
7fcadf62 | 1472 | /* Try to predict out blocks in a loop that are not part of a |
1473 | natural loop. */ | |
f21d4d00 | 1474 | FOR_EACH_LOOP (loop, 0) |
59423b59 | 1475 | { |
7fb12188 | 1476 | basic_block bb, *bbs; |
749ea85f | 1477 | unsigned j, n_exits; |
f1f41a6c | 1478 | vec<edge> exits; |
3b0b2309 | 1479 | struct tree_niter_desc niter_desc; |
749ea85f | 1480 | edge ex; |
fd757b76 | 1481 | struct nb_iter_bound *nb_iter; |
1482 | enum tree_code loop_bound_code = ERROR_MARK; | |
b3269f54 | 1483 | tree loop_bound_step = NULL; |
fd757b76 | 1484 | tree loop_bound_var = NULL; |
1485 | tree loop_iv_base = NULL; | |
1a91d914 | 1486 | gcond *stmt = NULL; |
59423b59 | 1487 | |
749ea85f | 1488 | exits = get_loop_exit_edges (loop); |
f1f41a6c | 1489 | n_exits = exits.length (); |
5d865361 | 1490 | if (!n_exits) |
1491 | { | |
f1f41a6c | 1492 | exits.release (); |
5d865361 | 1493 | continue; |
1494 | } | |
ba38e12b | 1495 | |
f1f41a6c | 1496 | FOR_EACH_VEC_ELT (exits, j, ex) |
d27b0b64 | 1497 | { |
3b0b2309 | 1498 | tree niter = NULL; |
d500fef3 | 1499 | HOST_WIDE_INT nitercst; |
1500 | int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS); | |
1501 | int probability; | |
1502 | enum br_predictor predictor; | |
d27b0b64 | 1503 | |
4ca17abf | 1504 | predict_extra_loop_exits (ex); |
1505 | ||
3f78e715 | 1506 | if (number_of_iterations_exit (loop, ex, &niter_desc, false, false)) |
3b0b2309 | 1507 | niter = niter_desc.niter; |
1508 | if (!niter || TREE_CODE (niter_desc.niter) != INTEGER_CST) | |
749ea85f | 1509 | niter = loop_niter_by_eval (loop, ex); |
d27b0b64 | 1510 | |
3b0b2309 | 1511 | if (TREE_CODE (niter) == INTEGER_CST) |
1512 | { | |
e913b5cd | 1513 | if (tree_fits_uhwi_p (niter) |
ed60f27f | 1514 | && max |
1515 | && compare_tree_int (niter, max - 1) == -1) | |
e913b5cd | 1516 | nitercst = tree_to_uhwi (niter) + 1; |
3b0b2309 | 1517 | else |
d500fef3 | 1518 | nitercst = max; |
1519 | predictor = PRED_LOOP_ITERATIONS; | |
1520 | } | |
1521 | /* If we have just one exit and we can derive some information about | |
1522 | the number of iterations of the loop from the statements inside | |
1523 | the loop, use it to predict this exit. */ | |
1524 | else if (n_exits == 1) | |
1525 | { | |
fee017b3 | 1526 | nitercst = estimated_stmt_executions_int (loop); |
d500fef3 | 1527 | if (nitercst < 0) |
1528 | continue; | |
1529 | if (nitercst > max) | |
1530 | nitercst = max; | |
d27b0b64 | 1531 | |
d500fef3 | 1532 | predictor = PRED_LOOP_ITERATIONS_GUESSED; |
3b0b2309 | 1533 | } |
d500fef3 | 1534 | else |
1535 | continue; | |
1536 | ||
ed60f27f | 1537 | /* If the prediction for number of iterations is zero, do not |
1538 | predict the exit edges. */ | |
1539 | if (nitercst == 0) | |
1540 | continue; | |
1541 | ||
d500fef3 | 1542 | probability = ((REG_BR_PROB_BASE + nitercst / 2) / nitercst); |
1543 | predict_edge (ex, predictor, probability); | |
d27b0b64 | 1544 | } |
f1f41a6c | 1545 | exits.release (); |
862be747 | 1546 | |
fd757b76 | 1547 | /* Find information about loop bound variables. */ |
1548 | for (nb_iter = loop->bounds; nb_iter; | |
1549 | nb_iter = nb_iter->next) | |
1550 | if (nb_iter->stmt | |
1551 | && gimple_code (nb_iter->stmt) == GIMPLE_COND) | |
1552 | { | |
1a91d914 | 1553 | stmt = as_a <gcond *> (nb_iter->stmt); |
fd757b76 | 1554 | break; |
1555 | } | |
1556 | if (!stmt && last_stmt (loop->header) | |
1557 | && gimple_code (last_stmt (loop->header)) == GIMPLE_COND) | |
1a91d914 | 1558 | stmt = as_a <gcond *> (last_stmt (loop->header)); |
fd757b76 | 1559 | if (stmt) |
1560 | is_comparison_with_loop_invariant_p (stmt, loop, | |
1561 | &loop_bound_var, | |
1562 | &loop_bound_code, | |
1563 | &loop_bound_step, | |
1564 | &loop_iv_base); | |
1565 | ||
7fb12188 | 1566 | bbs = get_loop_body (loop); |
4ee9c684 | 1567 | |
7fb12188 | 1568 | for (j = 0; j < loop->num_nodes; j++) |
1569 | { | |
1570 | int header_found = 0; | |
1571 | edge e; | |
cd665a06 | 1572 | edge_iterator ei; |
7fb12188 | 1573 | |
1574 | bb = bbs[j]; | |
e6751e9a | 1575 | |
cd0fe062 | 1576 | /* Bypass loop heuristics on continue statement. These |
1577 | statements construct loops via "non-loop" constructs | |
1578 | in the source language and are better to be handled | |
1579 | separately. */ | |
3b0b2309 | 1580 | if (predicted_by_p (bb, PRED_CONTINUE)) |
cd0fe062 | 1581 | continue; |
1582 | ||
7fb12188 | 1583 | /* Loop branch heuristics - predict an edge back to a |
1584 | loop's head as taken. */ | |
c6356c17 | 1585 | if (bb == loop->latch) |
1586 | { | |
1587 | e = find_edge (loop->latch, loop->header); | |
1588 | if (e) | |
1589 | { | |
1590 | header_found = 1; | |
1591 | predict_edge_def (e, PRED_LOOP_BRANCH, TAKEN); | |
1592 | } | |
1593 | } | |
e6751e9a | 1594 | |
7fb12188 | 1595 | /* Loop exit heuristics - predict an edge exiting the loop if the |
41a6f238 | 1596 | conditional has no loop header successors as not taken. */ |
d500fef3 | 1597 | if (!header_found |
1598 | /* If we already used more reliable loop exit predictors, do not | |
1599 | bother with PRED_LOOP_EXIT. */ | |
1600 | && !predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED) | |
1601 | && !predicted_by_p (bb, PRED_LOOP_ITERATIONS)) | |
b41438e5 | 1602 | { |
1603 | /* For loop with many exits we don't want to predict all exits | |
1604 | with the pretty large probability, because if all exits are | |
1605 | considered in row, the loop would be predicted to iterate | |
1606 | almost never. The code to divide probability by number of | |
1607 | exits is very rough. It should compute the number of exits | |
1608 | taken in each patch through function (not the overall number | |
1609 | of exits that might be a lot higher for loops with wide switch | |
1610 | statements in them) and compute n-th square root. | |
1611 | ||
1612 | We limit the minimal probability by 2% to avoid | |
1613 | EDGE_PROBABILITY_RELIABLE from trusting the branch prediction | |
1614 | as this was causing regression in perl benchmark containing such | |
1615 | a wide loop. */ | |
48e1416a | 1616 | |
b41438e5 | 1617 | int probability = ((REG_BR_PROB_BASE |
1618 | - predictor_info [(int) PRED_LOOP_EXIT].hitrate) | |
1619 | / n_exits); | |
1620 | if (probability < HITRATE (2)) | |
1621 | probability = HITRATE (2); | |
1622 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1623 | if (e->dest->index < NUM_FIXED_BLOCKS | |
1624 | || !flow_bb_inside_loop_p (loop, e->dest)) | |
1625 | predict_edge (e, PRED_LOOP_EXIT, probability); | |
1626 | } | |
fd757b76 | 1627 | if (loop_bound_var) |
1628 | predict_iv_comparison (loop, bb, loop_bound_var, loop_iv_base, | |
1629 | loop_bound_code, | |
e913b5cd | 1630 | tree_to_shwi (loop_bound_step)); |
7fb12188 | 1631 | } |
48e1416a | 1632 | |
21dda4ee | 1633 | /* Free basic blocks from get_loop_body. */ |
dcd8fd01 | 1634 | free (bbs); |
59423b59 | 1635 | } |
4ee9c684 | 1636 | } |
1637 | ||
83c8a977 | 1638 | /* Attempt to predict probabilities of BB outgoing edges using local |
1639 | properties. */ | |
1640 | static void | |
1641 | bb_estimate_probability_locally (basic_block bb) | |
1642 | { | |
ee5f6585 | 1643 | rtx_insn *last_insn = BB_END (bb); |
83c8a977 | 1644 | rtx cond; |
1645 | ||
1646 | if (! can_predict_insn_p (last_insn)) | |
1647 | return; | |
1648 | cond = get_condition (last_insn, NULL, false, false); | |
1649 | if (! cond) | |
1650 | return; | |
1651 | ||
1652 | /* Try "pointer heuristic." | |
1653 | A comparison ptr == 0 is predicted as false. | |
1654 | Similarly, a comparison ptr1 == ptr2 is predicted as false. */ | |
1655 | if (COMPARISON_P (cond) | |
1656 | && ((REG_P (XEXP (cond, 0)) && REG_POINTER (XEXP (cond, 0))) | |
1657 | || (REG_P (XEXP (cond, 1)) && REG_POINTER (XEXP (cond, 1))))) | |
1658 | { | |
1659 | if (GET_CODE (cond) == EQ) | |
1660 | predict_insn_def (last_insn, PRED_POINTER, NOT_TAKEN); | |
1661 | else if (GET_CODE (cond) == NE) | |
1662 | predict_insn_def (last_insn, PRED_POINTER, TAKEN); | |
1663 | } | |
1664 | else | |
1665 | ||
1666 | /* Try "opcode heuristic." | |
1667 | EQ tests are usually false and NE tests are usually true. Also, | |
1668 | most quantities are positive, so we can make the appropriate guesses | |
1669 | about signed comparisons against zero. */ | |
1670 | switch (GET_CODE (cond)) | |
1671 | { | |
1672 | case CONST_INT: | |
1673 | /* Unconditional branch. */ | |
1674 | predict_insn_def (last_insn, PRED_UNCONDITIONAL, | |
1675 | cond == const0_rtx ? NOT_TAKEN : TAKEN); | |
1676 | break; | |
1677 | ||
1678 | case EQ: | |
1679 | case UNEQ: | |
1680 | /* Floating point comparisons appears to behave in a very | |
1681 | unpredictable way because of special role of = tests in | |
1682 | FP code. */ | |
1683 | if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0)))) | |
1684 | ; | |
1685 | /* Comparisons with 0 are often used for booleans and there is | |
1686 | nothing useful to predict about them. */ | |
1687 | else if (XEXP (cond, 1) == const0_rtx | |
1688 | || XEXP (cond, 0) == const0_rtx) | |
1689 | ; | |
1690 | else | |
1691 | predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, NOT_TAKEN); | |
1692 | break; | |
1693 | ||
1694 | case NE: | |
1695 | case LTGT: | |
1696 | /* Floating point comparisons appears to behave in a very | |
1697 | unpredictable way because of special role of = tests in | |
1698 | FP code. */ | |
1699 | if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0)))) | |
1700 | ; | |
1701 | /* Comparisons with 0 are often used for booleans and there is | |
1702 | nothing useful to predict about them. */ | |
1703 | else if (XEXP (cond, 1) == const0_rtx | |
1704 | || XEXP (cond, 0) == const0_rtx) | |
1705 | ; | |
1706 | else | |
1707 | predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, TAKEN); | |
1708 | break; | |
1709 | ||
1710 | case ORDERED: | |
1711 | predict_insn_def (last_insn, PRED_FPOPCODE, TAKEN); | |
1712 | break; | |
1713 | ||
1714 | case UNORDERED: | |
1715 | predict_insn_def (last_insn, PRED_FPOPCODE, NOT_TAKEN); | |
1716 | break; | |
1717 | ||
1718 | case LE: | |
1719 | case LT: | |
1720 | if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx | |
1721 | || XEXP (cond, 1) == constm1_rtx) | |
1722 | predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, NOT_TAKEN); | |
1723 | break; | |
1724 | ||
1725 | case GE: | |
1726 | case GT: | |
1727 | if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx | |
1728 | || XEXP (cond, 1) == constm1_rtx) | |
1729 | predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, TAKEN); | |
1730 | break; | |
1731 | ||
1732 | default: | |
1733 | break; | |
1734 | } | |
1735 | } | |
1736 | ||
7edd21a5 | 1737 | /* Set edge->probability for each successor edge of BB. */ |
83c8a977 | 1738 | void |
1739 | guess_outgoing_edge_probabilities (basic_block bb) | |
1740 | { | |
1741 | bb_estimate_probability_locally (bb); | |
1742 | combine_predictions_for_insn (BB_END (bb), bb); | |
1743 | } | |
4ee9c684 | 1744 | \f |
c83059be | 1745 | static tree expr_expected_value (tree, bitmap, enum br_predictor *predictor); |
75a70cf9 | 1746 | |
1747 | /* Helper function for expr_expected_value. */ | |
42975b1f | 1748 | |
1749 | static tree | |
2380e91e | 1750 | expr_expected_value_1 (tree type, tree op0, enum tree_code code, |
c83059be | 1751 | tree op1, bitmap visited, enum br_predictor *predictor) |
42975b1f | 1752 | { |
75a70cf9 | 1753 | gimple def; |
1754 | ||
c83059be | 1755 | if (predictor) |
1756 | *predictor = PRED_UNCONDITIONAL; | |
1757 | ||
75a70cf9 | 1758 | if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS) |
42975b1f | 1759 | { |
75a70cf9 | 1760 | if (TREE_CONSTANT (op0)) |
1761 | return op0; | |
1762 | ||
1763 | if (code != SSA_NAME) | |
1764 | return NULL_TREE; | |
1765 | ||
1766 | def = SSA_NAME_DEF_STMT (op0); | |
42975b1f | 1767 | |
1768 | /* If we were already here, break the infinite cycle. */ | |
6ef9bbe0 | 1769 | if (!bitmap_set_bit (visited, SSA_NAME_VERSION (op0))) |
42975b1f | 1770 | return NULL; |
42975b1f | 1771 | |
75a70cf9 | 1772 | if (gimple_code (def) == GIMPLE_PHI) |
42975b1f | 1773 | { |
1774 | /* All the arguments of the PHI node must have the same constant | |
1775 | length. */ | |
75a70cf9 | 1776 | int i, n = gimple_phi_num_args (def); |
42975b1f | 1777 | tree val = NULL, new_val; |
4ee9c684 | 1778 | |
75a70cf9 | 1779 | for (i = 0; i < n; i++) |
42975b1f | 1780 | { |
1781 | tree arg = PHI_ARG_DEF (def, i); | |
c83059be | 1782 | enum br_predictor predictor2; |
42975b1f | 1783 | |
1784 | /* If this PHI has itself as an argument, we cannot | |
1785 | determine the string length of this argument. However, | |
86481e89 | 1786 | if we can find an expected constant value for the other |
42975b1f | 1787 | PHI args then we can still be sure that this is |
1788 | likely a constant. So be optimistic and just | |
1789 | continue with the next argument. */ | |
1790 | if (arg == PHI_RESULT (def)) | |
1791 | continue; | |
1792 | ||
c83059be | 1793 | new_val = expr_expected_value (arg, visited, &predictor2); |
1794 | ||
1795 | /* It is difficult to combine value predictors. Simply assume | |
1796 | that later predictor is weaker and take its prediction. */ | |
1797 | if (predictor && *predictor < predictor2) | |
1798 | *predictor = predictor2; | |
42975b1f | 1799 | if (!new_val) |
1800 | return NULL; | |
1801 | if (!val) | |
1802 | val = new_val; | |
1803 | else if (!operand_equal_p (val, new_val, false)) | |
1804 | return NULL; | |
1805 | } | |
1806 | return val; | |
1807 | } | |
75a70cf9 | 1808 | if (is_gimple_assign (def)) |
42975b1f | 1809 | { |
75a70cf9 | 1810 | if (gimple_assign_lhs (def) != op0) |
1811 | return NULL; | |
42975b1f | 1812 | |
75a70cf9 | 1813 | return expr_expected_value_1 (TREE_TYPE (gimple_assign_lhs (def)), |
1814 | gimple_assign_rhs1 (def), | |
1815 | gimple_assign_rhs_code (def), | |
1816 | gimple_assign_rhs2 (def), | |
c83059be | 1817 | visited, predictor); |
75a70cf9 | 1818 | } |
1819 | ||
1820 | if (is_gimple_call (def)) | |
1821 | { | |
1822 | tree decl = gimple_call_fndecl (def); | |
1823 | if (!decl) | |
c83059be | 1824 | { |
1825 | if (gimple_call_internal_p (def) | |
1826 | && gimple_call_internal_fn (def) == IFN_BUILTIN_EXPECT) | |
1827 | { | |
1828 | gcc_assert (gimple_call_num_args (def) == 3); | |
1829 | tree val = gimple_call_arg (def, 0); | |
1830 | if (TREE_CONSTANT (val)) | |
1831 | return val; | |
1832 | if (predictor) | |
1833 | { | |
c83059be | 1834 | tree val2 = gimple_call_arg (def, 2); |
1835 | gcc_assert (TREE_CODE (val2) == INTEGER_CST | |
1836 | && tree_fits_uhwi_p (val2) | |
1837 | && tree_to_uhwi (val2) < END_PREDICTORS); | |
1838 | *predictor = (enum br_predictor) tree_to_uhwi (val2); | |
1839 | } | |
1840 | return gimple_call_arg (def, 1); | |
1841 | } | |
1842 | return NULL; | |
1843 | } | |
2380e91e | 1844 | if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL) |
1845 | switch (DECL_FUNCTION_CODE (decl)) | |
1846 | { | |
1847 | case BUILT_IN_EXPECT: | |
1848 | { | |
1849 | tree val; | |
1850 | if (gimple_call_num_args (def) != 2) | |
1851 | return NULL; | |
1852 | val = gimple_call_arg (def, 0); | |
1853 | if (TREE_CONSTANT (val)) | |
1854 | return val; | |
c83059be | 1855 | if (predictor) |
1856 | *predictor = PRED_BUILTIN_EXPECT; | |
2380e91e | 1857 | return gimple_call_arg (def, 1); |
1858 | } | |
75a70cf9 | 1859 | |
2380e91e | 1860 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_N: |
1861 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_1: | |
1862 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2: | |
1863 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4: | |
1864 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8: | |
1865 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16: | |
1866 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE: | |
1867 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_N: | |
1868 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1: | |
1869 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2: | |
1870 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4: | |
1871 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8: | |
1872 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16: | |
1873 | /* Assume that any given atomic operation has low contention, | |
1874 | and thus the compare-and-swap operation succeeds. */ | |
c83059be | 1875 | if (predictor) |
1876 | *predictor = PRED_COMPARE_AND_SWAP; | |
2380e91e | 1877 | return boolean_true_node; |
5213d6c9 | 1878 | default: |
1879 | break; | |
75a70cf9 | 1880 | } |
42975b1f | 1881 | } |
75a70cf9 | 1882 | |
1883 | return NULL; | |
42975b1f | 1884 | } |
75a70cf9 | 1885 | |
1886 | if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS) | |
42975b1f | 1887 | { |
75a70cf9 | 1888 | tree res; |
c83059be | 1889 | enum br_predictor predictor2; |
1890 | op0 = expr_expected_value (op0, visited, predictor); | |
42975b1f | 1891 | if (!op0) |
1892 | return NULL; | |
c83059be | 1893 | op1 = expr_expected_value (op1, visited, &predictor2); |
1894 | if (predictor && *predictor < predictor2) | |
1895 | *predictor = predictor2; | |
42975b1f | 1896 | if (!op1) |
1897 | return NULL; | |
75a70cf9 | 1898 | res = fold_build2 (code, type, op0, op1); |
42975b1f | 1899 | if (TREE_CONSTANT (res)) |
1900 | return res; | |
1901 | return NULL; | |
1902 | } | |
75a70cf9 | 1903 | if (get_gimple_rhs_class (code) == GIMPLE_UNARY_RHS) |
42975b1f | 1904 | { |
75a70cf9 | 1905 | tree res; |
c83059be | 1906 | op0 = expr_expected_value (op0, visited, predictor); |
42975b1f | 1907 | if (!op0) |
1908 | return NULL; | |
75a70cf9 | 1909 | res = fold_build1 (code, type, op0); |
42975b1f | 1910 | if (TREE_CONSTANT (res)) |
1911 | return res; | |
1912 | return NULL; | |
1913 | } | |
1914 | return NULL; | |
1915 | } | |
75a70cf9 | 1916 | |
48e1416a | 1917 | /* Return constant EXPR will likely have at execution time, NULL if unknown. |
75a70cf9 | 1918 | The function is used by builtin_expect branch predictor so the evidence |
1919 | must come from this construct and additional possible constant folding. | |
48e1416a | 1920 | |
75a70cf9 | 1921 | We may want to implement more involved value guess (such as value range |
1922 | propagation based prediction), but such tricks shall go to new | |
1923 | implementation. */ | |
1924 | ||
1925 | static tree | |
c83059be | 1926 | expr_expected_value (tree expr, bitmap visited, |
1927 | enum br_predictor *predictor) | |
75a70cf9 | 1928 | { |
1929 | enum tree_code code; | |
1930 | tree op0, op1; | |
1931 | ||
1932 | if (TREE_CONSTANT (expr)) | |
c83059be | 1933 | { |
1934 | if (predictor) | |
1935 | *predictor = PRED_UNCONDITIONAL; | |
1936 | return expr; | |
1937 | } | |
75a70cf9 | 1938 | |
1939 | extract_ops_from_tree (expr, &code, &op0, &op1); | |
1940 | return expr_expected_value_1 (TREE_TYPE (expr), | |
c83059be | 1941 | op0, code, op1, visited, predictor); |
75a70cf9 | 1942 | } |
42975b1f | 1943 | \f |
4ee9c684 | 1944 | /* Predict using opcode of the last statement in basic block. */ |
1945 | static void | |
1946 | tree_predict_by_opcode (basic_block bb) | |
1947 | { | |
75a70cf9 | 1948 | gimple stmt = last_stmt (bb); |
4ee9c684 | 1949 | edge then_edge; |
75a70cf9 | 1950 | tree op0, op1; |
4ee9c684 | 1951 | tree type; |
42975b1f | 1952 | tree val; |
75a70cf9 | 1953 | enum tree_code cmp; |
42975b1f | 1954 | bitmap visited; |
cd665a06 | 1955 | edge_iterator ei; |
c83059be | 1956 | enum br_predictor predictor; |
4ee9c684 | 1957 | |
75a70cf9 | 1958 | if (!stmt || gimple_code (stmt) != GIMPLE_COND) |
4ee9c684 | 1959 | return; |
cd665a06 | 1960 | FOR_EACH_EDGE (then_edge, ei, bb->succs) |
4ee9c684 | 1961 | if (then_edge->flags & EDGE_TRUE_VALUE) |
cd665a06 | 1962 | break; |
75a70cf9 | 1963 | op0 = gimple_cond_lhs (stmt); |
1964 | op1 = gimple_cond_rhs (stmt); | |
1965 | cmp = gimple_cond_code (stmt); | |
4ee9c684 | 1966 | type = TREE_TYPE (op0); |
27335ffd | 1967 | visited = BITMAP_ALLOC (NULL); |
c83059be | 1968 | val = expr_expected_value_1 (boolean_type_node, op0, cmp, op1, visited, |
1969 | &predictor); | |
27335ffd | 1970 | BITMAP_FREE (visited); |
c83059be | 1971 | if (val && TREE_CODE (val) == INTEGER_CST) |
42975b1f | 1972 | { |
c83059be | 1973 | if (predictor == PRED_BUILTIN_EXPECT) |
1974 | { | |
1975 | int percent = PARAM_VALUE (BUILTIN_EXPECT_PROBABILITY); | |
21853731 | 1976 | |
c83059be | 1977 | gcc_assert (percent >= 0 && percent <= 100); |
1978 | if (integer_zerop (val)) | |
1979 | percent = 100 - percent; | |
1980 | predict_edge (then_edge, PRED_BUILTIN_EXPECT, HITRATE (percent)); | |
1981 | } | |
1982 | else | |
1983 | predict_edge (then_edge, predictor, | |
1984 | integer_zerop (val) ? NOT_TAKEN : TAKEN); | |
42975b1f | 1985 | } |
4ee9c684 | 1986 | /* Try "pointer heuristic." |
1987 | A comparison ptr == 0 is predicted as false. | |
1988 | Similarly, a comparison ptr1 == ptr2 is predicted as false. */ | |
1989 | if (POINTER_TYPE_P (type)) | |
1990 | { | |
75a70cf9 | 1991 | if (cmp == EQ_EXPR) |
4ee9c684 | 1992 | predict_edge_def (then_edge, PRED_TREE_POINTER, NOT_TAKEN); |
75a70cf9 | 1993 | else if (cmp == NE_EXPR) |
4ee9c684 | 1994 | predict_edge_def (then_edge, PRED_TREE_POINTER, TAKEN); |
1995 | } | |
1996 | else | |
1997 | ||
1998 | /* Try "opcode heuristic." | |
1999 | EQ tests are usually false and NE tests are usually true. Also, | |
2000 | most quantities are positive, so we can make the appropriate guesses | |
2001 | about signed comparisons against zero. */ | |
75a70cf9 | 2002 | switch (cmp) |
4ee9c684 | 2003 | { |
2004 | case EQ_EXPR: | |
2005 | case UNEQ_EXPR: | |
2006 | /* Floating point comparisons appears to behave in a very | |
2007 | unpredictable way because of special role of = tests in | |
2008 | FP code. */ | |
2009 | if (FLOAT_TYPE_P (type)) | |
2010 | ; | |
2011 | /* Comparisons with 0 are often used for booleans and there is | |
2012 | nothing useful to predict about them. */ | |
75a70cf9 | 2013 | else if (integer_zerop (op0) || integer_zerop (op1)) |
4ee9c684 | 2014 | ; |
2015 | else | |
2016 | predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, NOT_TAKEN); | |
2017 | break; | |
2018 | ||
2019 | case NE_EXPR: | |
318a728f | 2020 | case LTGT_EXPR: |
4ee9c684 | 2021 | /* Floating point comparisons appears to behave in a very |
2022 | unpredictable way because of special role of = tests in | |
2023 | FP code. */ | |
2024 | if (FLOAT_TYPE_P (type)) | |
2025 | ; | |
2026 | /* Comparisons with 0 are often used for booleans and there is | |
2027 | nothing useful to predict about them. */ | |
2028 | else if (integer_zerop (op0) | |
75a70cf9 | 2029 | || integer_zerop (op1)) |
4ee9c684 | 2030 | ; |
2031 | else | |
2032 | predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, TAKEN); | |
2033 | break; | |
2034 | ||
2035 | case ORDERED_EXPR: | |
2036 | predict_edge_def (then_edge, PRED_TREE_FPOPCODE, TAKEN); | |
2037 | break; | |
2038 | ||
2039 | case UNORDERED_EXPR: | |
2040 | predict_edge_def (then_edge, PRED_TREE_FPOPCODE, NOT_TAKEN); | |
2041 | break; | |
2042 | ||
2043 | case LE_EXPR: | |
2044 | case LT_EXPR: | |
75a70cf9 | 2045 | if (integer_zerop (op1) |
2046 | || integer_onep (op1) | |
2047 | || integer_all_onesp (op1) | |
2048 | || real_zerop (op1) | |
2049 | || real_onep (op1) | |
2050 | || real_minus_onep (op1)) | |
4ee9c684 | 2051 | predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, NOT_TAKEN); |
2052 | break; | |
2053 | ||
2054 | case GE_EXPR: | |
2055 | case GT_EXPR: | |
75a70cf9 | 2056 | if (integer_zerop (op1) |
2057 | || integer_onep (op1) | |
2058 | || integer_all_onesp (op1) | |
2059 | || real_zerop (op1) | |
2060 | || real_onep (op1) | |
2061 | || real_minus_onep (op1)) | |
4ee9c684 | 2062 | predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, TAKEN); |
2063 | break; | |
2064 | ||
2065 | default: | |
2066 | break; | |
2067 | } | |
2068 | } | |
2069 | ||
f816ec49 | 2070 | /* Try to guess whether the value of return means error code. */ |
75a70cf9 | 2071 | |
f816ec49 | 2072 | static enum br_predictor |
2073 | return_prediction (tree val, enum prediction *prediction) | |
2074 | { | |
2075 | /* VOID. */ | |
2076 | if (!val) | |
2077 | return PRED_NO_PREDICTION; | |
2078 | /* Different heuristics for pointers and scalars. */ | |
2079 | if (POINTER_TYPE_P (TREE_TYPE (val))) | |
2080 | { | |
2081 | /* NULL is usually not returned. */ | |
2082 | if (integer_zerop (val)) | |
2083 | { | |
2084 | *prediction = NOT_TAKEN; | |
2085 | return PRED_NULL_RETURN; | |
2086 | } | |
2087 | } | |
2088 | else if (INTEGRAL_TYPE_P (TREE_TYPE (val))) | |
2089 | { | |
2090 | /* Negative return values are often used to indicate | |
2091 | errors. */ | |
2092 | if (TREE_CODE (val) == INTEGER_CST | |
2093 | && tree_int_cst_sgn (val) < 0) | |
2094 | { | |
2095 | *prediction = NOT_TAKEN; | |
2096 | return PRED_NEGATIVE_RETURN; | |
2097 | } | |
2098 | /* Constant return values seems to be commonly taken. | |
2099 | Zero/one often represent booleans so exclude them from the | |
2100 | heuristics. */ | |
2101 | if (TREE_CONSTANT (val) | |
2102 | && (!integer_zerop (val) && !integer_onep (val))) | |
2103 | { | |
2104 | *prediction = TAKEN; | |
4a4e4487 | 2105 | return PRED_CONST_RETURN; |
f816ec49 | 2106 | } |
2107 | } | |
2108 | return PRED_NO_PREDICTION; | |
2109 | } | |
2110 | ||
2111 | /* Find the basic block with return expression and look up for possible | |
2112 | return value trying to apply RETURN_PREDICTION heuristics. */ | |
2113 | static void | |
d704ea82 | 2114 | apply_return_prediction (void) |
f816ec49 | 2115 | { |
1a91d914 | 2116 | greturn *return_stmt = NULL; |
f816ec49 | 2117 | tree return_val; |
2118 | edge e; | |
1a91d914 | 2119 | gphi *phi; |
f816ec49 | 2120 | int phi_num_args, i; |
2121 | enum br_predictor pred; | |
2122 | enum prediction direction; | |
cd665a06 | 2123 | edge_iterator ei; |
f816ec49 | 2124 | |
34154e27 | 2125 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) |
f816ec49 | 2126 | { |
1a91d914 | 2127 | gimple last = last_stmt (e->src); |
2128 | if (last | |
2129 | && gimple_code (last) == GIMPLE_RETURN) | |
2130 | { | |
2131 | return_stmt = as_a <greturn *> (last); | |
2132 | break; | |
2133 | } | |
f816ec49 | 2134 | } |
2135 | if (!e) | |
2136 | return; | |
75a70cf9 | 2137 | return_val = gimple_return_retval (return_stmt); |
f816ec49 | 2138 | if (!return_val) |
2139 | return; | |
f816ec49 | 2140 | if (TREE_CODE (return_val) != SSA_NAME |
2141 | || !SSA_NAME_DEF_STMT (return_val) | |
75a70cf9 | 2142 | || gimple_code (SSA_NAME_DEF_STMT (return_val)) != GIMPLE_PHI) |
f816ec49 | 2143 | return; |
1a91d914 | 2144 | phi = as_a <gphi *> (SSA_NAME_DEF_STMT (return_val)); |
75a70cf9 | 2145 | phi_num_args = gimple_phi_num_args (phi); |
f816ec49 | 2146 | pred = return_prediction (PHI_ARG_DEF (phi, 0), &direction); |
2147 | ||
2148 | /* Avoid the degenerate case where all return values form the function | |
2149 | belongs to same category (ie they are all positive constants) | |
2150 | so we can hardly say something about them. */ | |
2151 | for (i = 1; i < phi_num_args; i++) | |
2152 | if (pred != return_prediction (PHI_ARG_DEF (phi, i), &direction)) | |
2153 | break; | |
2154 | if (i != phi_num_args) | |
2155 | for (i = 0; i < phi_num_args; i++) | |
2156 | { | |
2157 | pred = return_prediction (PHI_ARG_DEF (phi, i), &direction); | |
2158 | if (pred != PRED_NO_PREDICTION) | |
5707768a | 2159 | predict_paths_leading_to_edge (gimple_phi_arg_edge (phi, i), pred, |
2160 | direction); | |
f816ec49 | 2161 | } |
2162 | } | |
2163 | ||
2164 | /* Look for basic block that contains unlikely to happen events | |
2165 | (such as noreturn calls) and mark all paths leading to execution | |
2166 | of this basic blocks as unlikely. */ | |
2167 | ||
2168 | static void | |
2169 | tree_bb_level_predictions (void) | |
2170 | { | |
2171 | basic_block bb; | |
9f694a82 | 2172 | bool has_return_edges = false; |
2173 | edge e; | |
2174 | edge_iterator ei; | |
2175 | ||
34154e27 | 2176 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) |
9f694a82 | 2177 | if (!(e->flags & (EDGE_ABNORMAL | EDGE_FAKE | EDGE_EH))) |
2178 | { | |
2179 | has_return_edges = true; | |
2180 | break; | |
2181 | } | |
f816ec49 | 2182 | |
d704ea82 | 2183 | apply_return_prediction (); |
f816ec49 | 2184 | |
fc00614f | 2185 | FOR_EACH_BB_FN (bb, cfun) |
f816ec49 | 2186 | { |
75a70cf9 | 2187 | gimple_stmt_iterator gsi; |
f816ec49 | 2188 | |
1add270f | 2189 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
f816ec49 | 2190 | { |
75a70cf9 | 2191 | gimple stmt = gsi_stmt (gsi); |
5de92639 | 2192 | tree decl; |
3ed4a4a1 | 2193 | |
75a70cf9 | 2194 | if (is_gimple_call (stmt)) |
f816ec49 | 2195 | { |
9f694a82 | 2196 | if ((gimple_call_flags (stmt) & ECF_NORETURN) |
2197 | && has_return_edges) | |
75a70cf9 | 2198 | predict_paths_leading_to (bb, PRED_NORETURN, |
2199 | NOT_TAKEN); | |
2200 | decl = gimple_call_fndecl (stmt); | |
2201 | if (decl | |
2202 | && lookup_attribute ("cold", | |
2203 | DECL_ATTRIBUTES (decl))) | |
2204 | predict_paths_leading_to (bb, PRED_COLD_FUNCTION, | |
2205 | NOT_TAKEN); | |
f816ec49 | 2206 | } |
75a70cf9 | 2207 | else if (gimple_code (stmt) == GIMPLE_PREDICT) |
2208 | { | |
2209 | predict_paths_leading_to (bb, gimple_predict_predictor (stmt), | |
2210 | gimple_predict_outcome (stmt)); | |
1add270f | 2211 | /* Keep GIMPLE_PREDICT around so early inlining will propagate |
2212 | hints to callers. */ | |
75a70cf9 | 2213 | } |
f816ec49 | 2214 | } |
2215 | } | |
f816ec49 | 2216 | } |
2217 | ||
b3723726 | 2218 | #ifdef ENABLE_CHECKING |
2219 | ||
06ecf488 | 2220 | /* Callback for hash_map::traverse, asserts that the pointer map is |
b3723726 | 2221 | empty. */ |
2222 | ||
06ecf488 | 2223 | bool |
2224 | assert_is_empty (const_basic_block const &, edge_prediction *const &value, | |
2225 | void *) | |
b3723726 | 2226 | { |
06ecf488 | 2227 | gcc_assert (!value); |
b3723726 | 2228 | return false; |
2229 | } | |
2230 | #endif | |
2231 | ||
675d86b2 | 2232 | /* Predict branch probabilities and estimate profile for basic block BB. */ |
2233 | ||
2234 | static void | |
2235 | tree_estimate_probability_bb (basic_block bb) | |
2236 | { | |
2237 | edge e; | |
2238 | edge_iterator ei; | |
2239 | gimple last; | |
2240 | ||
2241 | FOR_EACH_EDGE (e, ei, bb->succs) | |
2242 | { | |
758a38ab | 2243 | /* Predict edges to user labels with attributes. */ |
34154e27 | 2244 | if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)) |
758a38ab | 2245 | { |
2246 | gimple_stmt_iterator gi; | |
2247 | for (gi = gsi_start_bb (e->dest); !gsi_end_p (gi); gsi_next (&gi)) | |
2248 | { | |
1a91d914 | 2249 | glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gi)); |
758a38ab | 2250 | tree decl; |
2251 | ||
1a91d914 | 2252 | if (!label_stmt) |
758a38ab | 2253 | break; |
1a91d914 | 2254 | decl = gimple_label_label (label_stmt); |
758a38ab | 2255 | if (DECL_ARTIFICIAL (decl)) |
2256 | continue; | |
2257 | ||
2258 | /* Finally, we have a user-defined label. */ | |
2259 | if (lookup_attribute ("cold", DECL_ATTRIBUTES (decl))) | |
2260 | predict_edge_def (e, PRED_COLD_LABEL, NOT_TAKEN); | |
2261 | else if (lookup_attribute ("hot", DECL_ATTRIBUTES (decl))) | |
2262 | predict_edge_def (e, PRED_HOT_LABEL, TAKEN); | |
2263 | } | |
2264 | } | |
2265 | ||
675d86b2 | 2266 | /* Predict early returns to be probable, as we've already taken |
2267 | care for error returns and other cases are often used for | |
2268 | fast paths through function. | |
2269 | ||
2270 | Since we've already removed the return statements, we are | |
2271 | looking for CFG like: | |
2272 | ||
2273 | if (conditional) | |
2274 | { | |
2275 | .. | |
2276 | goto return_block | |
2277 | } | |
2278 | some other blocks | |
2279 | return_block: | |
2280 | return_stmt. */ | |
2281 | if (e->dest != bb->next_bb | |
34154e27 | 2282 | && e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) |
675d86b2 | 2283 | && single_succ_p (e->dest) |
34154e27 | 2284 | && single_succ_edge (e->dest)->dest == EXIT_BLOCK_PTR_FOR_FN (cfun) |
675d86b2 | 2285 | && (last = last_stmt (e->dest)) != NULL |
2286 | && gimple_code (last) == GIMPLE_RETURN) | |
2287 | { | |
2288 | edge e1; | |
2289 | edge_iterator ei1; | |
2290 | ||
2291 | if (single_succ_p (bb)) | |
2292 | { | |
2293 | FOR_EACH_EDGE (e1, ei1, bb->preds) | |
2294 | if (!predicted_by_p (e1->src, PRED_NULL_RETURN) | |
2295 | && !predicted_by_p (e1->src, PRED_CONST_RETURN) | |
2296 | && !predicted_by_p (e1->src, PRED_NEGATIVE_RETURN)) | |
2297 | predict_edge_def (e1, PRED_TREE_EARLY_RETURN, NOT_TAKEN); | |
2298 | } | |
2299 | else | |
2300 | if (!predicted_by_p (e->src, PRED_NULL_RETURN) | |
2301 | && !predicted_by_p (e->src, PRED_CONST_RETURN) | |
2302 | && !predicted_by_p (e->src, PRED_NEGATIVE_RETURN)) | |
2303 | predict_edge_def (e, PRED_TREE_EARLY_RETURN, NOT_TAKEN); | |
2304 | } | |
2305 | ||
2306 | /* Look for block we are guarding (ie we dominate it, | |
2307 | but it doesn't postdominate us). */ | |
34154e27 | 2308 | if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) && e->dest != bb |
675d86b2 | 2309 | && dominated_by_p (CDI_DOMINATORS, e->dest, e->src) |
2310 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e->dest)) | |
2311 | { | |
2312 | gimple_stmt_iterator bi; | |
2313 | ||
2314 | /* The call heuristic claims that a guarded function call | |
2315 | is improbable. This is because such calls are often used | |
2316 | to signal exceptional situations such as printing error | |
2317 | messages. */ | |
2318 | for (bi = gsi_start_bb (e->dest); !gsi_end_p (bi); | |
2319 | gsi_next (&bi)) | |
2320 | { | |
2321 | gimple stmt = gsi_stmt (bi); | |
2322 | if (is_gimple_call (stmt) | |
2323 | /* Constant and pure calls are hardly used to signalize | |
2324 | something exceptional. */ | |
2325 | && gimple_has_side_effects (stmt)) | |
2326 | { | |
2327 | predict_edge_def (e, PRED_CALL, NOT_TAKEN); | |
2328 | break; | |
2329 | } | |
2330 | } | |
2331 | } | |
2332 | } | |
2333 | tree_predict_by_opcode (bb); | |
2334 | } | |
2335 | ||
2336 | /* Predict branch probabilities and estimate profile of the tree CFG. | |
2337 | This function can be called from the loop optimizers to recompute | |
2338 | the profile information. */ | |
2339 | ||
2340 | void | |
4ee9c684 | 2341 | tree_estimate_probability (void) |
2342 | { | |
2343 | basic_block bb; | |
4ee9c684 | 2344 | |
f816ec49 | 2345 | add_noreturn_fake_exit_edges (); |
4ee9c684 | 2346 | connect_infinite_loops_to_exit (); |
d8a0d6b8 | 2347 | /* We use loop_niter_by_eval, which requires that the loops have |
2348 | preheaders. */ | |
2349 | create_preheaders (CP_SIMPLE_PREHEADERS); | |
4ee9c684 | 2350 | calculate_dominance_info (CDI_POST_DOMINATORS); |
2351 | ||
06ecf488 | 2352 | bb_predictions = new hash_map<const_basic_block, edge_prediction *>; |
f816ec49 | 2353 | tree_bb_level_predictions (); |
d500fef3 | 2354 | record_loop_exits (); |
675d86b2 | 2355 | |
41f75a99 | 2356 | if (number_of_loops (cfun) > 1) |
7194de72 | 2357 | predict_loops (); |
4ee9c684 | 2358 | |
fc00614f | 2359 | FOR_EACH_BB_FN (bb, cfun) |
675d86b2 | 2360 | tree_estimate_probability_bb (bb); |
4ee9c684 | 2361 | |
fc00614f | 2362 | FOR_EACH_BB_FN (bb, cfun) |
3f5be5f4 | 2363 | combine_predictions_for_bb (bb); |
f81d9f78 | 2364 | |
b3723726 | 2365 | #ifdef ENABLE_CHECKING |
06ecf488 | 2366 | bb_predictions->traverse<void *, assert_is_empty> (NULL); |
b3723726 | 2367 | #endif |
06ecf488 | 2368 | delete bb_predictions; |
b3723726 | 2369 | bb_predictions = NULL; |
2370 | ||
5327650f | 2371 | estimate_bb_frequencies (false); |
4ee9c684 | 2372 | free_dominance_info (CDI_POST_DOMINATORS); |
41d24834 | 2373 | remove_fake_exit_edges (); |
675d86b2 | 2374 | } |
89cfe6e5 | 2375 | \f |
f0b5f617 | 2376 | /* Predict edges to successors of CUR whose sources are not postdominated by |
d704ea82 | 2377 | BB by PRED and recurse to all postdominators. */ |
f816ec49 | 2378 | |
2379 | static void | |
d704ea82 | 2380 | predict_paths_for_bb (basic_block cur, basic_block bb, |
2381 | enum br_predictor pred, | |
d3443011 | 2382 | enum prediction taken, |
2383 | bitmap visited) | |
f816ec49 | 2384 | { |
2385 | edge e; | |
cd665a06 | 2386 | edge_iterator ei; |
d704ea82 | 2387 | basic_block son; |
f816ec49 | 2388 | |
d704ea82 | 2389 | /* We are looking for all edges forming edge cut induced by |
2390 | set of all blocks postdominated by BB. */ | |
2391 | FOR_EACH_EDGE (e, ei, cur->preds) | |
2392 | if (e->src->index >= NUM_FIXED_BLOCKS | |
2393 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, bb)) | |
f816ec49 | 2394 | { |
f1d5a92b | 2395 | edge e2; |
2396 | edge_iterator ei2; | |
2397 | bool found = false; | |
2398 | ||
5707768a | 2399 | /* Ignore fake edges and eh, we predict them as not taken anyway. */ |
2400 | if (e->flags & (EDGE_EH | EDGE_FAKE)) | |
f1d5a92b | 2401 | continue; |
d704ea82 | 2402 | gcc_assert (bb == cur || dominated_by_p (CDI_POST_DOMINATORS, cur, bb)); |
f1d5a92b | 2403 | |
d3443011 | 2404 | /* See if there is an edge from e->src that is not abnormal |
f1d5a92b | 2405 | and does not lead to BB. */ |
2406 | FOR_EACH_EDGE (e2, ei2, e->src->succs) | |
2407 | if (e2 != e | |
5707768a | 2408 | && !(e2->flags & (EDGE_EH | EDGE_FAKE)) |
f1d5a92b | 2409 | && !dominated_by_p (CDI_POST_DOMINATORS, e2->dest, bb)) |
2410 | { | |
2411 | found = true; | |
2412 | break; | |
2413 | } | |
2414 | ||
2415 | /* If there is non-abnormal path leaving e->src, predict edge | |
2416 | using predictor. Otherwise we need to look for paths | |
d3443011 | 2417 | leading to e->src. |
2418 | ||
2419 | The second may lead to infinite loop in the case we are predicitng | |
2420 | regions that are only reachable by abnormal edges. We simply | |
2421 | prevent visiting given BB twice. */ | |
f1d5a92b | 2422 | if (found) |
2423 | predict_edge_def (e, pred, taken); | |
6e3803fb | 2424 | else if (bitmap_set_bit (visited, e->src->index)) |
d3443011 | 2425 | predict_paths_for_bb (e->src, e->src, pred, taken, visited); |
f816ec49 | 2426 | } |
d704ea82 | 2427 | for (son = first_dom_son (CDI_POST_DOMINATORS, cur); |
2428 | son; | |
2429 | son = next_dom_son (CDI_POST_DOMINATORS, son)) | |
d3443011 | 2430 | predict_paths_for_bb (son, bb, pred, taken, visited); |
d704ea82 | 2431 | } |
f816ec49 | 2432 | |
d704ea82 | 2433 | /* Sets branch probabilities according to PREDiction and |
2434 | FLAGS. */ | |
f816ec49 | 2435 | |
d704ea82 | 2436 | static void |
2437 | predict_paths_leading_to (basic_block bb, enum br_predictor pred, | |
2438 | enum prediction taken) | |
2439 | { | |
d3443011 | 2440 | bitmap visited = BITMAP_ALLOC (NULL); |
2441 | predict_paths_for_bb (bb, bb, pred, taken, visited); | |
2442 | BITMAP_FREE (visited); | |
f816ec49 | 2443 | } |
5707768a | 2444 | |
2445 | /* Like predict_paths_leading_to but take edge instead of basic block. */ | |
2446 | ||
2447 | static void | |
2448 | predict_paths_leading_to_edge (edge e, enum br_predictor pred, | |
2449 | enum prediction taken) | |
2450 | { | |
2451 | bool has_nonloop_edge = false; | |
2452 | edge_iterator ei; | |
2453 | edge e2; | |
2454 | ||
2455 | basic_block bb = e->src; | |
2456 | FOR_EACH_EDGE (e2, ei, bb->succs) | |
2457 | if (e2->dest != e->src && e2->dest != e->dest | |
2458 | && !(e->flags & (EDGE_EH | EDGE_FAKE)) | |
2459 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e2->dest)) | |
2460 | { | |
2461 | has_nonloop_edge = true; | |
2462 | break; | |
2463 | } | |
2464 | if (!has_nonloop_edge) | |
d3443011 | 2465 | { |
2466 | bitmap visited = BITMAP_ALLOC (NULL); | |
2467 | predict_paths_for_bb (bb, bb, pred, taken, visited); | |
2468 | BITMAP_FREE (visited); | |
2469 | } | |
5707768a | 2470 | else |
2471 | predict_edge_def (e, pred, taken); | |
2472 | } | |
cd0fe062 | 2473 | \f |
e725f898 | 2474 | /* This is used to carry information about basic blocks. It is |
f81d9f78 | 2475 | attached to the AUX field of the standard CFG block. */ |
2476 | ||
9908fe4d | 2477 | struct block_info |
f81d9f78 | 2478 | { |
2479 | /* Estimated frequency of execution of basic_block. */ | |
e9d7220b | 2480 | sreal frequency; |
f81d9f78 | 2481 | |
2482 | /* To keep queue of basic blocks to process. */ | |
2483 | basic_block next; | |
2484 | ||
4a82352a | 2485 | /* Number of predecessors we need to visit first. */ |
4ad72a03 | 2486 | int npredecessors; |
9908fe4d | 2487 | }; |
f81d9f78 | 2488 | |
2489 | /* Similar information for edges. */ | |
9908fe4d | 2490 | struct edge_prob_info |
f81d9f78 | 2491 | { |
77aa6362 | 2492 | /* In case edge is a loopback edge, the probability edge will be reached |
f81d9f78 | 2493 | in case header is. Estimated number of iterations of the loop can be |
56ff4880 | 2494 | then computed as 1 / (1 - back_edge_prob). */ |
e9d7220b | 2495 | sreal back_edge_prob; |
77aa6362 | 2496 | /* True if the edge is a loopback edge in the natural loop. */ |
74cbb553 | 2497 | unsigned int back_edge:1; |
9908fe4d | 2498 | }; |
f81d9f78 | 2499 | |
9908fe4d | 2500 | #define BLOCK_INFO(B) ((block_info *) (B)->aux) |
886c1262 | 2501 | #undef EDGE_INFO |
9908fe4d | 2502 | #define EDGE_INFO(E) ((edge_prob_info *) (E)->aux) |
f81d9f78 | 2503 | |
2504 | /* Helper function for estimate_bb_frequencies. | |
88e6f696 | 2505 | Propagate the frequencies in blocks marked in |
2506 | TOVISIT, starting in HEAD. */ | |
e6751e9a | 2507 | |
f81d9f78 | 2508 | static void |
88e6f696 | 2509 | propagate_freq (basic_block head, bitmap tovisit) |
f81d9f78 | 2510 | { |
4c26117a | 2511 | basic_block bb; |
2512 | basic_block last; | |
9ea83aa5 | 2513 | unsigned i; |
f81d9f78 | 2514 | edge e; |
2515 | basic_block nextbb; | |
b1bb9b10 | 2516 | bitmap_iterator bi; |
312866af | 2517 | |
4a82352a | 2518 | /* For each basic block we need to visit count number of his predecessors |
312866af | 2519 | we need to visit first. */ |
b1bb9b10 | 2520 | EXECUTE_IF_SET_IN_BITMAP (tovisit, 0, i, bi) |
312866af | 2521 | { |
b1bb9b10 | 2522 | edge_iterator ei; |
2523 | int count = 0; | |
2524 | ||
f5a6b05f | 2525 | bb = BASIC_BLOCK_FOR_FN (cfun, i); |
e6751e9a | 2526 | |
b1bb9b10 | 2527 | FOR_EACH_EDGE (e, ei, bb->preds) |
2528 | { | |
2529 | bool visit = bitmap_bit_p (tovisit, e->src->index); | |
2530 | ||
2531 | if (visit && !(e->flags & EDGE_DFS_BACK)) | |
2532 | count++; | |
2533 | else if (visit && dump_file && !EDGE_INFO (e)->back_edge) | |
2534 | fprintf (dump_file, | |
2535 | "Irreducible region hit, ignoring edge to %i->%i\n", | |
2536 | e->src->index, bb->index); | |
312866af | 2537 | } |
9ea83aa5 | 2538 | BLOCK_INFO (bb)->npredecessors = count; |
555e8b05 | 2539 | /* When function never returns, we will never process exit block. */ |
34154e27 | 2540 | if (!count && bb == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
555e8b05 | 2541 | bb->count = bb->frequency = 0; |
312866af | 2542 | } |
f81d9f78 | 2543 | |
23a92fc7 | 2544 | BLOCK_INFO (head)->frequency = real_one; |
4c26117a | 2545 | last = head; |
2546 | for (bb = head; bb; bb = nextbb) | |
f81d9f78 | 2547 | { |
cd665a06 | 2548 | edge_iterator ei; |
23a92fc7 | 2549 | sreal cyclic_probability = real_zero; |
2550 | sreal frequency = real_zero; | |
f81d9f78 | 2551 | |
2552 | nextbb = BLOCK_INFO (bb)->next; | |
2553 | BLOCK_INFO (bb)->next = NULL; | |
2554 | ||
2555 | /* Compute frequency of basic block. */ | |
2556 | if (bb != head) | |
2557 | { | |
312866af | 2558 | #ifdef ENABLE_CHECKING |
cd665a06 | 2559 | FOR_EACH_EDGE (e, ei, bb->preds) |
876760f6 | 2560 | gcc_assert (!bitmap_bit_p (tovisit, e->src->index) |
2561 | || (e->flags & EDGE_DFS_BACK)); | |
312866af | 2562 | #endif |
f81d9f78 | 2563 | |
cd665a06 | 2564 | FOR_EACH_EDGE (e, ei, bb->preds) |
f81d9f78 | 2565 | if (EDGE_INFO (e)->back_edge) |
56ff4880 | 2566 | { |
23a92fc7 | 2567 | cyclic_probability += EDGE_INFO (e)->back_edge_prob; |
56ff4880 | 2568 | } |
312866af | 2569 | else if (!(e->flags & EDGE_DFS_BACK)) |
56ff4880 | 2570 | { |
56ff4880 | 2571 | /* frequency += (e->probability |
2572 | * BLOCK_INFO (e->src)->frequency / | |
2573 | REG_BR_PROB_BASE); */ | |
2574 | ||
23a92fc7 | 2575 | sreal tmp (e->probability, 0); |
2576 | tmp *= BLOCK_INFO (e->src)->frequency; | |
2577 | tmp *= real_inv_br_prob_base; | |
2578 | frequency += tmp; | |
56ff4880 | 2579 | } |
2580 | ||
23a92fc7 | 2581 | if (cyclic_probability == real_zero) |
e9d7220b | 2582 | { |
23a92fc7 | 2583 | BLOCK_INFO (bb)->frequency = frequency; |
e9d7220b | 2584 | } |
2e3c56e8 | 2585 | else |
2586 | { | |
23a92fc7 | 2587 | if (cyclic_probability > real_almost_one) |
2588 | cyclic_probability = real_almost_one; | |
f81d9f78 | 2589 | |
d598ad0d | 2590 | /* BLOCK_INFO (bb)->frequency = frequency |
e9d7220b | 2591 | / (1 - cyclic_probability) */ |
f81d9f78 | 2592 | |
23a92fc7 | 2593 | cyclic_probability = real_one - cyclic_probability; |
2594 | BLOCK_INFO (bb)->frequency = frequency / cyclic_probability; | |
2e3c56e8 | 2595 | } |
f81d9f78 | 2596 | } |
2597 | ||
b1bb9b10 | 2598 | bitmap_clear_bit (tovisit, bb->index); |
f81d9f78 | 2599 | |
c6356c17 | 2600 | e = find_edge (bb, head); |
2601 | if (e) | |
2602 | { | |
c6356c17 | 2603 | /* EDGE_INFO (e)->back_edge_prob |
2604 | = ((e->probability * BLOCK_INFO (bb)->frequency) | |
2605 | / REG_BR_PROB_BASE); */ | |
48e1416a | 2606 | |
23a92fc7 | 2607 | sreal tmp (e->probability, 0); |
2608 | tmp *= BLOCK_INFO (bb)->frequency; | |
2609 | EDGE_INFO (e)->back_edge_prob = tmp * real_inv_br_prob_base; | |
c6356c17 | 2610 | } |
f81d9f78 | 2611 | |
e725f898 | 2612 | /* Propagate to successor blocks. */ |
cd665a06 | 2613 | FOR_EACH_EDGE (e, ei, bb->succs) |
312866af | 2614 | if (!(e->flags & EDGE_DFS_BACK) |
4ad72a03 | 2615 | && BLOCK_INFO (e->dest)->npredecessors) |
f81d9f78 | 2616 | { |
4ad72a03 | 2617 | BLOCK_INFO (e->dest)->npredecessors--; |
2618 | if (!BLOCK_INFO (e->dest)->npredecessors) | |
312866af | 2619 | { |
2620 | if (!nextbb) | |
2621 | nextbb = e->dest; | |
2622 | else | |
2623 | BLOCK_INFO (last)->next = e->dest; | |
48e1416a | 2624 | |
312866af | 2625 | last = e->dest; |
2626 | } | |
cd665a06 | 2627 | } |
f81d9f78 | 2628 | } |
2629 | } | |
2630 | ||
5327650f | 2631 | /* Estimate frequencies in loops at same nest level. */ |
e6751e9a | 2632 | |
f81d9f78 | 2633 | static void |
88e6f696 | 2634 | estimate_loops_at_level (struct loop *first_loop) |
f81d9f78 | 2635 | { |
7fb12188 | 2636 | struct loop *loop; |
f81d9f78 | 2637 | |
2638 | for (loop = first_loop; loop; loop = loop->next) | |
2639 | { | |
f81d9f78 | 2640 | edge e; |
7fb12188 | 2641 | basic_block *bbs; |
862be747 | 2642 | unsigned i; |
88e6f696 | 2643 | bitmap tovisit = BITMAP_ALLOC (NULL); |
f81d9f78 | 2644 | |
88e6f696 | 2645 | estimate_loops_at_level (loop->inner); |
d598ad0d | 2646 | |
88e6f696 | 2647 | /* Find current loop back edge and mark it. */ |
2648 | e = loop_latch_edge (loop); | |
2649 | EDGE_INFO (e)->back_edge = 1; | |
7fb12188 | 2650 | |
2651 | bbs = get_loop_body (loop); | |
2652 | for (i = 0; i < loop->num_nodes; i++) | |
b1bb9b10 | 2653 | bitmap_set_bit (tovisit, bbs[i]->index); |
7fb12188 | 2654 | free (bbs); |
88e6f696 | 2655 | propagate_freq (loop->header, tovisit); |
2656 | BITMAP_FREE (tovisit); | |
f81d9f78 | 2657 | } |
2658 | } | |
2659 | ||
fa7637bd | 2660 | /* Propagates frequencies through structure of loops. */ |
88e6f696 | 2661 | |
2662 | static void | |
7194de72 | 2663 | estimate_loops (void) |
88e6f696 | 2664 | { |
2665 | bitmap tovisit = BITMAP_ALLOC (NULL); | |
2666 | basic_block bb; | |
2667 | ||
2668 | /* Start by estimating the frequencies in the loops. */ | |
41f75a99 | 2669 | if (number_of_loops (cfun) > 1) |
7194de72 | 2670 | estimate_loops_at_level (current_loops->tree_root->inner); |
88e6f696 | 2671 | |
2672 | /* Now propagate the frequencies through all the blocks. */ | |
ed7d889a | 2673 | FOR_ALL_BB_FN (bb, cfun) |
88e6f696 | 2674 | { |
2675 | bitmap_set_bit (tovisit, bb->index); | |
2676 | } | |
34154e27 | 2677 | propagate_freq (ENTRY_BLOCK_PTR_FOR_FN (cfun), tovisit); |
88e6f696 | 2678 | BITMAP_FREE (tovisit); |
2679 | } | |
2680 | ||
38a65d4e | 2681 | /* Drop the profile for NODE to guessed, and update its frequency based on |
901d3ddc | 2682 | whether it is expected to be hot given the CALL_COUNT. */ |
38a65d4e | 2683 | |
2684 | static void | |
901d3ddc | 2685 | drop_profile (struct cgraph_node *node, gcov_type call_count) |
38a65d4e | 2686 | { |
2687 | struct function *fn = DECL_STRUCT_FUNCTION (node->decl); | |
901d3ddc | 2688 | /* In the case where this was called by another function with a |
2689 | dropped profile, call_count will be 0. Since there are no | |
2690 | non-zero call counts to this function, we don't know for sure | |
2691 | whether it is hot, and therefore it will be marked normal below. */ | |
2692 | bool hot = maybe_hot_count_p (NULL, call_count); | |
38a65d4e | 2693 | |
2694 | if (dump_file) | |
2695 | fprintf (dump_file, | |
2696 | "Dropping 0 profile for %s/%i. %s based on calls.\n", | |
f1c8b4d7 | 2697 | node->name (), node->order, |
38a65d4e | 2698 | hot ? "Function is hot" : "Function is normal"); |
2699 | /* We only expect to miss profiles for functions that are reached | |
2700 | via non-zero call edges in cases where the function may have | |
2701 | been linked from another module or library (COMDATs and extern | |
901d3ddc | 2702 | templates). See the comments below for handle_missing_profiles. |
2703 | Also, only warn in cases where the missing counts exceed the | |
2704 | number of training runs. In certain cases with an execv followed | |
2705 | by a no-return call the profile for the no-return call is not | |
2706 | dumped and there can be a mismatch. */ | |
2707 | if (!DECL_COMDAT (node->decl) && !DECL_EXTERNAL (node->decl) | |
2708 | && call_count > profile_info->runs) | |
38a65d4e | 2709 | { |
2710 | if (flag_profile_correction) | |
2711 | { | |
2712 | if (dump_file) | |
2713 | fprintf (dump_file, | |
2714 | "Missing counts for called function %s/%i\n", | |
f1c8b4d7 | 2715 | node->name (), node->order); |
38a65d4e | 2716 | } |
2717 | else | |
901d3ddc | 2718 | warning (0, "Missing counts for called function %s/%i", |
f1c8b4d7 | 2719 | node->name (), node->order); |
38a65d4e | 2720 | } |
2721 | ||
3bedbae3 | 2722 | profile_status_for_fn (fn) |
38a65d4e | 2723 | = (flag_guess_branch_prob ? PROFILE_GUESSED : PROFILE_ABSENT); |
2724 | node->frequency | |
2725 | = hot ? NODE_FREQUENCY_HOT : NODE_FREQUENCY_NORMAL; | |
2726 | } | |
2727 | ||
2728 | /* In the case of COMDAT routines, multiple object files will contain the same | |
2729 | function and the linker will select one for the binary. In that case | |
2730 | all the other copies from the profile instrument binary will be missing | |
2731 | profile counts. Look for cases where this happened, due to non-zero | |
2732 | call counts going to 0-count functions, and drop the profile to guessed | |
2733 | so that we can use the estimated probabilities and avoid optimizing only | |
2734 | for size. | |
2735 | ||
2736 | The other case where the profile may be missing is when the routine | |
2737 | is not going to be emitted to the object file, e.g. for "extern template" | |
2738 | class methods. Those will be marked DECL_EXTERNAL. Emit a warning in | |
2739 | all other cases of non-zero calls to 0-count functions. */ | |
2740 | ||
2741 | void | |
2742 | handle_missing_profiles (void) | |
2743 | { | |
2744 | struct cgraph_node *node; | |
2745 | int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); | |
2746 | vec<struct cgraph_node *> worklist; | |
2747 | worklist.create (64); | |
2748 | ||
2749 | /* See if 0 count function has non-0 count callers. In this case we | |
2750 | lost some profile. Drop its function profile to PROFILE_GUESSED. */ | |
2751 | FOR_EACH_DEFINED_FUNCTION (node) | |
2752 | { | |
2753 | struct cgraph_edge *e; | |
2754 | gcov_type call_count = 0; | |
af48f0b1 | 2755 | gcov_type max_tp_first_run = 0; |
38a65d4e | 2756 | struct function *fn = DECL_STRUCT_FUNCTION (node->decl); |
2757 | ||
2758 | if (node->count) | |
2759 | continue; | |
2760 | for (e = node->callers; e; e = e->next_caller) | |
af48f0b1 | 2761 | { |
38a65d4e | 2762 | call_count += e->count; |
af48f0b1 | 2763 | |
2764 | if (e->caller->tp_first_run > max_tp_first_run) | |
2765 | max_tp_first_run = e->caller->tp_first_run; | |
2766 | } | |
2767 | ||
2768 | /* If time profile is missing, let assign the maximum that comes from | |
2769 | caller functions. */ | |
2770 | if (!node->tp_first_run && max_tp_first_run) | |
2771 | node->tp_first_run = max_tp_first_run + 1; | |
2772 | ||
38a65d4e | 2773 | if (call_count |
2774 | && fn && fn->cfg | |
2775 | && (call_count * unlikely_count_fraction >= profile_info->runs)) | |
2776 | { | |
901d3ddc | 2777 | drop_profile (node, call_count); |
38a65d4e | 2778 | worklist.safe_push (node); |
2779 | } | |
2780 | } | |
2781 | ||
2782 | /* Propagate the profile dropping to other 0-count COMDATs that are | |
2783 | potentially called by COMDATs we already dropped the profile on. */ | |
2784 | while (worklist.length () > 0) | |
2785 | { | |
2786 | struct cgraph_edge *e; | |
2787 | ||
2788 | node = worklist.pop (); | |
2789 | for (e = node->callees; e; e = e->next_caller) | |
2790 | { | |
2791 | struct cgraph_node *callee = e->callee; | |
2792 | struct function *fn = DECL_STRUCT_FUNCTION (callee->decl); | |
2793 | ||
2794 | if (callee->count > 0) | |
2795 | continue; | |
2796 | if (DECL_COMDAT (callee->decl) && fn && fn->cfg | |
3bedbae3 | 2797 | && profile_status_for_fn (fn) == PROFILE_READ) |
38a65d4e | 2798 | { |
901d3ddc | 2799 | drop_profile (node, 0); |
38a65d4e | 2800 | worklist.safe_push (callee); |
2801 | } | |
2802 | } | |
2803 | } | |
2804 | worklist.release (); | |
2805 | } | |
2806 | ||
3f18719c | 2807 | /* Convert counts measured by profile driven feedback to frequencies. |
2808 | Return nonzero iff there was any nonzero execution count. */ | |
e6751e9a | 2809 | |
ffedd254 | 2810 | int |
d598ad0d | 2811 | counts_to_freqs (void) |
f81d9f78 | 2812 | { |
3f18719c | 2813 | gcov_type count_max, true_count_max = 0; |
4c26117a | 2814 | basic_block bb; |
b3d6de89 | 2815 | |
38a65d4e | 2816 | /* Don't overwrite the estimated frequencies when the profile for |
2817 | the function is missing. We may drop this function PROFILE_GUESSED | |
2818 | later in drop_profile (). */ | |
94bed7c3 | 2819 | if (!flag_auto_profile && !ENTRY_BLOCK_PTR_FOR_FN (cfun)->count) |
38a65d4e | 2820 | return 0; |
2821 | ||
34154e27 | 2822 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
3f18719c | 2823 | true_count_max = MAX (bb->count, true_count_max); |
f81d9f78 | 2824 | |
3f18719c | 2825 | count_max = MAX (true_count_max, 1); |
34154e27 | 2826 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
4c26117a | 2827 | bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max; |
167b550b | 2828 | |
3f18719c | 2829 | return true_count_max; |
f81d9f78 | 2830 | } |
2831 | ||
e6751e9a | 2832 | /* Return true if function is likely to be expensive, so there is no point to |
2833 | optimize performance of prologue, epilogue or do inlining at the expense | |
41a6f238 | 2834 | of code size growth. THRESHOLD is the limit of number of instructions |
e6751e9a | 2835 | function can execute at average to be still considered not expensive. */ |
2836 | ||
f4c0c1a2 | 2837 | bool |
d598ad0d | 2838 | expensive_function_p (int threshold) |
f4c0c1a2 | 2839 | { |
2840 | unsigned int sum = 0; | |
4c26117a | 2841 | basic_block bb; |
27d0c333 | 2842 | unsigned int limit; |
f4c0c1a2 | 2843 | |
2844 | /* We can not compute accurately for large thresholds due to scaled | |
2845 | frequencies. */ | |
876760f6 | 2846 | gcc_assert (threshold <= BB_FREQ_MAX); |
f4c0c1a2 | 2847 | |
4a82352a | 2848 | /* Frequencies are out of range. This either means that function contains |
f4c0c1a2 | 2849 | internal loop executing more than BB_FREQ_MAX times or profile feedback |
2850 | is available and function has not been executed at all. */ | |
34154e27 | 2851 | if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency == 0) |
f4c0c1a2 | 2852 | return true; |
195731ad | 2853 | |
f4c0c1a2 | 2854 | /* Maximally BB_FREQ_MAX^2 so overflow won't happen. */ |
34154e27 | 2855 | limit = ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency * threshold; |
fc00614f | 2856 | FOR_EACH_BB_FN (bb, cfun) |
f4c0c1a2 | 2857 | { |
ee5f6585 | 2858 | rtx_insn *insn; |
f4c0c1a2 | 2859 | |
91f71fa3 | 2860 | FOR_BB_INSNS (bb, insn) |
e6751e9a | 2861 | if (active_insn_p (insn)) |
2862 | { | |
2863 | sum += bb->frequency; | |
2864 | if (sum > limit) | |
2865 | return true; | |
f4c0c1a2 | 2866 | } |
2867 | } | |
e6751e9a | 2868 | |
f4c0c1a2 | 2869 | return false; |
2870 | } | |
2871 | ||
5327650f | 2872 | /* Estimate and propagate basic block frequencies using the given branch |
2873 | probabilities. If FORCE is true, the frequencies are used to estimate | |
2874 | the counts even when there are already non-zero profile counts. */ | |
e6751e9a | 2875 | |
4ae20857 | 2876 | void |
5327650f | 2877 | estimate_bb_frequencies (bool force) |
f81d9f78 | 2878 | { |
4c26117a | 2879 | basic_block bb; |
e9d7220b | 2880 | sreal freq_max; |
56ff4880 | 2881 | |
f26d8580 | 2882 | if (force || profile_status_for_fn (cfun) != PROFILE_READ || !counts_to_freqs ()) |
429fa7fa | 2883 | { |
31e4010e | 2884 | static int real_values_initialized = 0; |
2885 | ||
2886 | if (!real_values_initialized) | |
2887 | { | |
fc22704f | 2888 | real_values_initialized = 1; |
23a92fc7 | 2889 | real_zero = sreal (0, 0); |
2890 | real_one = sreal (1, 0); | |
2891 | real_br_prob_base = sreal (REG_BR_PROB_BASE, 0); | |
2892 | real_bb_freq_max = sreal (BB_FREQ_MAX, 0); | |
2893 | real_one_half = sreal (1, -1); | |
2894 | real_inv_br_prob_base = real_one / real_br_prob_base; | |
2895 | real_almost_one = real_one - real_inv_br_prob_base; | |
31e4010e | 2896 | } |
f81d9f78 | 2897 | |
429fa7fa | 2898 | mark_dfs_back_edges (); |
429fa7fa | 2899 | |
34154e27 | 2900 | single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))->probability = |
2901 | REG_BR_PROB_BASE; | |
429fa7fa | 2902 | |
2903 | /* Set up block info for each basic block. */ | |
9908fe4d | 2904 | alloc_aux_for_blocks (sizeof (block_info)); |
2905 | alloc_aux_for_edges (sizeof (edge_prob_info)); | |
34154e27 | 2906 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
f81d9f78 | 2907 | { |
f81d9f78 | 2908 | edge e; |
cd665a06 | 2909 | edge_iterator ei; |
429fa7fa | 2910 | |
cd665a06 | 2911 | FOR_EACH_EDGE (e, ei, bb->succs) |
f81d9f78 | 2912 | { |
23a92fc7 | 2913 | EDGE_INFO (e)->back_edge_prob = sreal (e->probability, 0); |
2914 | EDGE_INFO (e)->back_edge_prob *= real_inv_br_prob_base; | |
f81d9f78 | 2915 | } |
f81d9f78 | 2916 | } |
e6751e9a | 2917 | |
5327650f | 2918 | /* First compute frequencies locally for each loop from innermost |
2919 | to outermost to examine frequencies for back edges. */ | |
7194de72 | 2920 | estimate_loops (); |
f81d9f78 | 2921 | |
23a92fc7 | 2922 | freq_max = real_zero; |
fc00614f | 2923 | FOR_EACH_BB_FN (bb, cfun) |
23a92fc7 | 2924 | if (freq_max < BLOCK_INFO (bb)->frequency) |
2925 | freq_max = BLOCK_INFO (bb)->frequency; | |
2e3c56e8 | 2926 | |
23a92fc7 | 2927 | freq_max = real_bb_freq_max / freq_max; |
34154e27 | 2928 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
56ff4880 | 2929 | { |
23a92fc7 | 2930 | sreal tmp = BLOCK_INFO (bb)->frequency * freq_max + real_one_half; |
2931 | bb->frequency = tmp.to_int (); | |
429fa7fa | 2932 | } |
e6751e9a | 2933 | |
429fa7fa | 2934 | free_aux_for_blocks (); |
2935 | free_aux_for_edges (); | |
2936 | } | |
2937 | compute_function_frequency (); | |
429fa7fa | 2938 | } |
f81d9f78 | 2939 | |
429fa7fa | 2940 | /* Decide whether function is hot, cold or unlikely executed. */ |
63aab97d | 2941 | void |
d598ad0d | 2942 | compute_function_frequency (void) |
429fa7fa | 2943 | { |
4c26117a | 2944 | basic_block bb; |
415d1b9a | 2945 | struct cgraph_node *node = cgraph_node::get (current_function_decl); |
e27f29dd | 2946 | |
0f9fb931 | 2947 | if (DECL_STATIC_CONSTRUCTOR (current_function_decl) |
2948 | || MAIN_NAME_P (DECL_NAME (current_function_decl))) | |
2949 | node->only_called_at_startup = true; | |
2950 | if (DECL_STATIC_DESTRUCTOR (current_function_decl)) | |
2951 | node->only_called_at_exit = true; | |
4c26117a | 2952 | |
f26d8580 | 2953 | if (profile_status_for_fn (cfun) != PROFILE_READ) |
5de92639 | 2954 | { |
125b6d78 | 2955 | int flags = flags_from_decl_or_type (current_function_decl); |
5de92639 | 2956 | if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl)) |
2957 | != NULL) | |
125b6d78 | 2958 | node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; |
5de92639 | 2959 | else if (lookup_attribute ("hot", DECL_ATTRIBUTES (current_function_decl)) |
2960 | != NULL) | |
125b6d78 | 2961 | node->frequency = NODE_FREQUENCY_HOT; |
2962 | else if (flags & ECF_NORETURN) | |
2963 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
2964 | else if (MAIN_NAME_P (DECL_NAME (current_function_decl))) | |
2965 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
2966 | else if (DECL_STATIC_CONSTRUCTOR (current_function_decl) | |
2967 | || DECL_STATIC_DESTRUCTOR (current_function_decl)) | |
2968 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
5de92639 | 2969 | return; |
2970 | } | |
e27f29dd | 2971 | |
2972 | /* Only first time try to drop function into unlikely executed. | |
2973 | After inlining the roundoff errors may confuse us. | |
2974 | Ipa-profile pass will drop functions only called from unlikely | |
2975 | functions to unlikely and that is most of what we care about. */ | |
2976 | if (!cfun->after_inlining) | |
2977 | node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; | |
fc00614f | 2978 | FOR_EACH_BB_FN (bb, cfun) |
f81d9f78 | 2979 | { |
8d672d12 | 2980 | if (maybe_hot_bb_p (cfun, bb)) |
429fa7fa | 2981 | { |
125b6d78 | 2982 | node->frequency = NODE_FREQUENCY_HOT; |
429fa7fa | 2983 | return; |
2984 | } | |
8d672d12 | 2985 | if (!probably_never_executed_bb_p (cfun, bb)) |
125b6d78 | 2986 | node->frequency = NODE_FREQUENCY_NORMAL; |
f81d9f78 | 2987 | } |
429fa7fa | 2988 | } |
f81d9f78 | 2989 | |
4a1849e3 | 2990 | /* Build PREDICT_EXPR. */ |
2991 | tree | |
2992 | build_predict_expr (enum br_predictor predictor, enum prediction taken) | |
2993 | { | |
08f62b1b | 2994 | tree t = build1 (PREDICT_EXPR, void_type_node, |
b3d480fb | 2995 | build_int_cst (integer_type_node, predictor)); |
b9c74b4d | 2996 | SET_PREDICT_EXPR_OUTCOME (t, taken); |
4a1849e3 | 2997 | return t; |
2998 | } | |
2999 | ||
3000 | const char * | |
3001 | predictor_name (enum br_predictor predictor) | |
3002 | { | |
3003 | return predictor_info[predictor].name; | |
3004 | } | |
3005 | ||
65b0537f | 3006 | /* Predict branch probabilities and estimate profile of the tree CFG. */ |
3007 | ||
cbe8bda8 | 3008 | namespace { |
3009 | ||
3010 | const pass_data pass_data_profile = | |
3011 | { | |
3012 | GIMPLE_PASS, /* type */ | |
3013 | "profile_estimate", /* name */ | |
3014 | OPTGROUP_NONE, /* optinfo_flags */ | |
cbe8bda8 | 3015 | TV_BRANCH_PROB, /* tv_id */ |
3016 | PROP_cfg, /* properties_required */ | |
3017 | 0, /* properties_provided */ | |
3018 | 0, /* properties_destroyed */ | |
3019 | 0, /* todo_flags_start */ | |
8b88439e | 3020 | 0, /* todo_flags_finish */ |
4ee9c684 | 3021 | }; |
1add270f | 3022 | |
cbe8bda8 | 3023 | class pass_profile : public gimple_opt_pass |
3024 | { | |
3025 | public: | |
9af5ce0c | 3026 | pass_profile (gcc::context *ctxt) |
3027 | : gimple_opt_pass (pass_data_profile, ctxt) | |
cbe8bda8 | 3028 | {} |
3029 | ||
3030 | /* opt_pass methods: */ | |
31315c24 | 3031 | virtual bool gate (function *) { return flag_guess_branch_prob; } |
65b0537f | 3032 | virtual unsigned int execute (function *); |
cbe8bda8 | 3033 | |
3034 | }; // class pass_profile | |
3035 | ||
65b0537f | 3036 | unsigned int |
3037 | pass_profile::execute (function *fun) | |
3038 | { | |
3039 | unsigned nb_loops; | |
3040 | ||
3041 | loop_optimizer_init (LOOPS_NORMAL); | |
3042 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3043 | flow_loops_dump (dump_file, NULL, 0); | |
3044 | ||
3045 | mark_irreducible_loops (); | |
3046 | ||
3047 | nb_loops = number_of_loops (fun); | |
3048 | if (nb_loops > 1) | |
3049 | scev_initialize (); | |
3050 | ||
3051 | tree_estimate_probability (); | |
3052 | ||
3053 | if (nb_loops > 1) | |
3054 | scev_finalize (); | |
3055 | ||
3056 | loop_optimizer_finalize (); | |
3057 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3058 | gimple_dump_cfg (dump_file, dump_flags); | |
3059 | if (profile_status_for_fn (fun) == PROFILE_ABSENT) | |
3060 | profile_status_for_fn (fun) = PROFILE_GUESSED; | |
3061 | return 0; | |
3062 | } | |
3063 | ||
cbe8bda8 | 3064 | } // anon namespace |
3065 | ||
3066 | gimple_opt_pass * | |
3067 | make_pass_profile (gcc::context *ctxt) | |
3068 | { | |
3069 | return new pass_profile (ctxt); | |
3070 | } | |
3071 | ||
3072 | namespace { | |
3073 | ||
3074 | const pass_data pass_data_strip_predict_hints = | |
3075 | { | |
3076 | GIMPLE_PASS, /* type */ | |
3077 | "*strip_predict_hints", /* name */ | |
3078 | OPTGROUP_NONE, /* optinfo_flags */ | |
cbe8bda8 | 3079 | TV_BRANCH_PROB, /* tv_id */ |
3080 | PROP_cfg, /* properties_required */ | |
3081 | 0, /* properties_provided */ | |
3082 | 0, /* properties_destroyed */ | |
3083 | 0, /* todo_flags_start */ | |
8b88439e | 3084 | 0, /* todo_flags_finish */ |
1add270f | 3085 | }; |
555e8b05 | 3086 | |
cbe8bda8 | 3087 | class pass_strip_predict_hints : public gimple_opt_pass |
3088 | { | |
3089 | public: | |
9af5ce0c | 3090 | pass_strip_predict_hints (gcc::context *ctxt) |
3091 | : gimple_opt_pass (pass_data_strip_predict_hints, ctxt) | |
cbe8bda8 | 3092 | {} |
3093 | ||
3094 | /* opt_pass methods: */ | |
ae84f584 | 3095 | opt_pass * clone () { return new pass_strip_predict_hints (m_ctxt); } |
65b0537f | 3096 | virtual unsigned int execute (function *); |
cbe8bda8 | 3097 | |
3098 | }; // class pass_strip_predict_hints | |
3099 | ||
65b0537f | 3100 | /* Get rid of all builtin_expect calls and GIMPLE_PREDICT statements |
3101 | we no longer need. */ | |
3102 | unsigned int | |
3103 | pass_strip_predict_hints::execute (function *fun) | |
3104 | { | |
3105 | basic_block bb; | |
3106 | gimple ass_stmt; | |
3107 | tree var; | |
3108 | ||
3109 | FOR_EACH_BB_FN (bb, fun) | |
3110 | { | |
3111 | gimple_stmt_iterator bi; | |
3112 | for (bi = gsi_start_bb (bb); !gsi_end_p (bi);) | |
3113 | { | |
3114 | gimple stmt = gsi_stmt (bi); | |
3115 | ||
3116 | if (gimple_code (stmt) == GIMPLE_PREDICT) | |
3117 | { | |
3118 | gsi_remove (&bi, true); | |
3119 | continue; | |
3120 | } | |
3121 | else if (is_gimple_call (stmt)) | |
3122 | { | |
3123 | tree fndecl = gimple_call_fndecl (stmt); | |
3124 | ||
3125 | if ((fndecl | |
3126 | && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL | |
3127 | && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT | |
3128 | && gimple_call_num_args (stmt) == 2) | |
3129 | || (gimple_call_internal_p (stmt) | |
3130 | && gimple_call_internal_fn (stmt) == IFN_BUILTIN_EXPECT)) | |
3131 | { | |
3132 | var = gimple_call_lhs (stmt); | |
3133 | if (var) | |
3134 | { | |
3135 | ass_stmt | |
3136 | = gimple_build_assign (var, gimple_call_arg (stmt, 0)); | |
3137 | gsi_replace (&bi, ass_stmt, true); | |
3138 | } | |
3139 | else | |
3140 | { | |
3141 | gsi_remove (&bi, true); | |
3142 | continue; | |
3143 | } | |
3144 | } | |
3145 | } | |
3146 | gsi_next (&bi); | |
3147 | } | |
3148 | } | |
3149 | return 0; | |
3150 | } | |
3151 | ||
cbe8bda8 | 3152 | } // anon namespace |
3153 | ||
3154 | gimple_opt_pass * | |
3155 | make_pass_strip_predict_hints (gcc::context *ctxt) | |
3156 | { | |
3157 | return new pass_strip_predict_hints (ctxt); | |
3158 | } | |
3159 | ||
555e8b05 | 3160 | /* Rebuild function frequencies. Passes are in general expected to |
3161 | maintain profile by hand, however in some cases this is not possible: | |
3162 | for example when inlining several functions with loops freuqencies might run | |
3163 | out of scale and thus needs to be recomputed. */ | |
3164 | ||
3165 | void | |
3166 | rebuild_frequencies (void) | |
3167 | { | |
4b366dd3 | 3168 | timevar_push (TV_REBUILD_FREQUENCIES); |
5327650f | 3169 | |
3170 | /* When the max bb count in the function is small, there is a higher | |
3171 | chance that there were truncation errors in the integer scaling | |
3172 | of counts by inlining and other optimizations. This could lead | |
3173 | to incorrect classification of code as being cold when it isn't. | |
3174 | In that case, force the estimation of bb counts/frequencies from the | |
3175 | branch probabilities, rather than computing frequencies from counts, | |
3176 | which may also lead to frequencies incorrectly reduced to 0. There | |
3177 | is less precision in the probabilities, so we only do this for small | |
3178 | max counts. */ | |
3179 | gcov_type count_max = 0; | |
3180 | basic_block bb; | |
34154e27 | 3181 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
5327650f | 3182 | count_max = MAX (bb->count, count_max); |
3183 | ||
f26d8580 | 3184 | if (profile_status_for_fn (cfun) == PROFILE_GUESSED |
94bed7c3 | 3185 | || (!flag_auto_profile && profile_status_for_fn (cfun) == PROFILE_READ |
3186 | && count_max < REG_BR_PROB_BASE/10)) | |
555e8b05 | 3187 | { |
3188 | loop_optimizer_init (0); | |
3189 | add_noreturn_fake_exit_edges (); | |
3190 | mark_irreducible_loops (); | |
3191 | connect_infinite_loops_to_exit (); | |
5327650f | 3192 | estimate_bb_frequencies (true); |
555e8b05 | 3193 | remove_fake_exit_edges (); |
3194 | loop_optimizer_finalize (); | |
3195 | } | |
f26d8580 | 3196 | else if (profile_status_for_fn (cfun) == PROFILE_READ) |
555e8b05 | 3197 | counts_to_freqs (); |
3198 | else | |
3199 | gcc_unreachable (); | |
4b366dd3 | 3200 | timevar_pop (TV_REBUILD_FREQUENCIES); |
555e8b05 | 3201 | } |