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59423b59 | 1 | /* Branch prediction routines for the GNU compiler. |
d353bf18 | 2 | Copyright (C) 2000-2015 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" | |
b20a8bb4 | 34 | #include "alias.h" |
35 | #include "symtab.h" | |
59423b59 | 36 | #include "tree.h" |
b20a8bb4 | 37 | #include "fold-const.h" |
9ed99284 | 38 | #include "calls.h" |
59423b59 | 39 | #include "rtl.h" |
40 | #include "tm_p.h" | |
d6cb6164 | 41 | #include "hard-reg-set.h" |
94ea8568 | 42 | #include "predict.h" |
59423b59 | 43 | #include "function.h" |
94ea8568 | 44 | #include "dominance.h" |
45 | #include "cfg.h" | |
46 | #include "cfganal.h" | |
47 | #include "basic-block.h" | |
48 | #include "insn-config.h" | |
49 | #include "regs.h" | |
50 | #include "flags.h" | |
886c1262 | 51 | #include "profile.h" |
59423b59 | 52 | #include "except.h" |
0b205f4c | 53 | #include "diagnostic-core.h" |
59423b59 | 54 | #include "recog.h" |
d53441c8 | 55 | #include "expmed.h" |
56 | #include "dojump.h" | |
57 | #include "explow.h" | |
58 | #include "emit-rtl.h" | |
59 | #include "varasm.h" | |
60 | #include "stmt.h" | |
59423b59 | 61 | #include "expr.h" |
e9fb8a64 | 62 | #include "coverage.h" |
e9d7220b | 63 | #include "sreal.h" |
429fa7fa | 64 | #include "params.h" |
65 | #include "target.h" | |
862be747 | 66 | #include "cfgloop.h" |
bc61cadb | 67 | #include "tree-ssa-alias.h" |
68 | #include "internal-fn.h" | |
69 | #include "gimple-expr.h" | |
073c1fd5 | 70 | #include "gimple.h" |
dcf1a1ec | 71 | #include "gimple-iterator.h" |
073c1fd5 | 72 | #include "gimple-ssa.h" |
1140c305 | 73 | #include "plugin-api.h" |
74 | #include "ipa-ref.h" | |
073c1fd5 | 75 | #include "cgraph.h" |
76 | #include "tree-cfg.h" | |
77 | #include "tree-phinodes.h" | |
78 | #include "ssa-iterators.h" | |
05d9c18a | 79 | #include "tree-ssa-loop-niter.h" |
073c1fd5 | 80 | #include "tree-ssa-loop.h" |
4ee9c684 | 81 | #include "tree-pass.h" |
d27b0b64 | 82 | #include "tree-scalar-evolution.h" |
56ff4880 | 83 | |
2e3c56e8 | 84 | /* real constants: 0, 1, 1-1/REG_BR_PROB_BASE, REG_BR_PROB_BASE, |
85 | 1/REG_BR_PROB_BASE, 0.5, BB_FREQ_MAX. */ | |
8201d1f6 | 86 | static sreal real_almost_one, real_br_prob_base, |
e9d7220b | 87 | real_inv_br_prob_base, real_one_half, real_bb_freq_max; |
59423b59 | 88 | |
ee5f6585 | 89 | static void combine_predictions_for_insn (rtx_insn *, basic_block); |
4ee9c684 | 90 | static void dump_prediction (FILE *, enum br_predictor, int, basic_block, int); |
d704ea82 | 91 | static void predict_paths_leading_to (basic_block, enum br_predictor, enum prediction); |
5707768a | 92 | static void predict_paths_leading_to_edge (edge, enum br_predictor, enum prediction); |
ee5f6585 | 93 | static bool can_predict_insn_p (const rtx_insn *); |
5e96f51e | 94 | |
13488c51 | 95 | /* Information we hold about each branch predictor. |
96 | Filled using information from predict.def. */ | |
e6751e9a | 97 | |
13488c51 | 98 | struct predictor_info |
5e96f51e | 99 | { |
e99c3a1d | 100 | const char *const name; /* Name used in the debugging dumps. */ |
101 | const int hitrate; /* Expected hitrate used by | |
102 | predict_insn_def call. */ | |
103 | const int flags; | |
13488c51 | 104 | }; |
5e96f51e | 105 | |
eb429644 | 106 | /* Use given predictor without Dempster-Shaffer theory if it matches |
107 | using first_match heuristics. */ | |
108 | #define PRED_FLAG_FIRST_MATCH 1 | |
109 | ||
110 | /* Recompute hitrate in percent to our representation. */ | |
111 | ||
e6751e9a | 112 | #define HITRATE(VAL) ((int) ((VAL) * REG_BR_PROB_BASE + 50) / 100) |
eb429644 | 113 | |
114 | #define DEF_PREDICTOR(ENUM, NAME, HITRATE, FLAGS) {NAME, HITRATE, FLAGS}, | |
e6751e9a | 115 | static const struct predictor_info predictor_info[]= { |
13488c51 | 116 | #include "predict.def" |
117 | ||
aa40f561 | 118 | /* Upper bound on predictors. */ |
eb429644 | 119 | {NULL, 0, 0} |
13488c51 | 120 | }; |
121 | #undef DEF_PREDICTOR | |
429fa7fa | 122 | |
eb7df8c2 | 123 | /* Return TRUE if frequency FREQ is considered to be hot. */ |
f29b326e | 124 | |
125 | static inline bool | |
8d672d12 | 126 | maybe_hot_frequency_p (struct function *fun, int freq) |
eb7df8c2 | 127 | { |
415d1b9a | 128 | struct cgraph_node *node = cgraph_node::get (fun->decl); |
69ad6a32 | 129 | if (!profile_info |
130 | || !opt_for_fn (fun->decl, flag_branch_probabilities)) | |
eb7df8c2 | 131 | { |
125b6d78 | 132 | if (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED) |
eb7df8c2 | 133 | return false; |
125b6d78 | 134 | if (node->frequency == NODE_FREQUENCY_HOT) |
eb7df8c2 | 135 | return true; |
136 | } | |
3bedbae3 | 137 | if (profile_status_for_fn (fun) == PROFILE_ABSENT) |
aa5f4f32 | 138 | return true; |
125b6d78 | 139 | if (node->frequency == NODE_FREQUENCY_EXECUTED_ONCE |
34154e27 | 140 | && freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency * 2 / 3)) |
125b6d78 | 141 | return false; |
6040d650 | 142 | if (PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) == 0) |
143 | return false; | |
34154e27 | 144 | if (freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency |
8d672d12 | 145 | / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))) |
eb7df8c2 | 146 | return false; |
147 | return true; | |
148 | } | |
149 | ||
9e179a64 | 150 | static gcov_type min_count = -1; |
151 | ||
152 | /* Determine the threshold for hot BB counts. */ | |
153 | ||
154 | gcov_type | |
155 | get_hot_bb_threshold () | |
156 | { | |
157 | gcov_working_set_t *ws; | |
158 | if (min_count == -1) | |
159 | { | |
160 | ws = find_working_set (PARAM_VALUE (HOT_BB_COUNT_WS_PERMILLE)); | |
161 | gcc_assert (ws); | |
162 | min_count = ws->min_counter; | |
163 | } | |
164 | return min_count; | |
165 | } | |
166 | ||
167 | /* Set the threshold for hot BB counts. */ | |
168 | ||
169 | void | |
170 | set_hot_bb_threshold (gcov_type min) | |
171 | { | |
172 | min_count = min; | |
173 | } | |
174 | ||
f29b326e | 175 | /* Return TRUE if frequency FREQ is considered to be hot. */ |
176 | ||
94bed7c3 | 177 | bool |
8d672d12 | 178 | maybe_hot_count_p (struct function *fun, gcov_type count) |
f29b326e | 179 | { |
3bedbae3 | 180 | if (fun && profile_status_for_fn (fun) != PROFILE_READ) |
f29b326e | 181 | return true; |
182 | /* Code executed at most once is not hot. */ | |
183 | if (profile_info->runs >= count) | |
184 | return false; | |
9e179a64 | 185 | return (count >= get_hot_bb_threshold ()); |
f29b326e | 186 | } |
187 | ||
429fa7fa | 188 | /* Return true in case BB can be CPU intensive and should be optimized |
41a6f238 | 189 | for maximal performance. */ |
429fa7fa | 190 | |
191 | bool | |
8d672d12 | 192 | maybe_hot_bb_p (struct function *fun, const_basic_block bb) |
429fa7fa | 193 | { |
8d672d12 | 194 | gcc_checking_assert (fun); |
3bedbae3 | 195 | if (profile_status_for_fn (fun) == PROFILE_READ) |
8d672d12 | 196 | return maybe_hot_count_p (fun, bb->count); |
197 | return maybe_hot_frequency_p (fun, bb->frequency); | |
eb7df8c2 | 198 | } |
199 | ||
200 | /* Return true in case BB can be CPU intensive and should be optimized | |
201 | for maximal performance. */ | |
202 | ||
203 | bool | |
204 | maybe_hot_edge_p (edge e) | |
205 | { | |
f26d8580 | 206 | if (profile_status_for_fn (cfun) == PROFILE_READ) |
8d672d12 | 207 | return maybe_hot_count_p (cfun, e->count); |
208 | return maybe_hot_frequency_p (cfun, EDGE_FREQUENCY (e)); | |
429fa7fa | 209 | } |
210 | ||
dcc9b351 | 211 | /* Return true if profile COUNT and FREQUENCY, or function FUN static |
212 | node frequency reflects never being executed. */ | |
213 | ||
214 | static bool | |
215 | probably_never_executed (struct function *fun, | |
216 | gcov_type count, int frequency) | |
429fa7fa | 217 | { |
8d672d12 | 218 | gcc_checking_assert (fun); |
69ad6a32 | 219 | if (profile_status_for_fn (fun) == PROFILE_READ) |
4befb9f4 | 220 | { |
c1acf60c | 221 | int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); |
222 | if (count * unlikely_count_fraction >= profile_info->runs) | |
4befb9f4 | 223 | return false; |
dcc9b351 | 224 | if (!frequency) |
4befb9f4 | 225 | return true; |
69ad6a32 | 226 | if (!ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency) |
4befb9f4 | 227 | return false; |
69ad6a32 | 228 | if (ENTRY_BLOCK_PTR_FOR_FN (fun)->count) |
4befb9f4 | 229 | { |
c1acf60c | 230 | gcov_type computed_count; |
231 | /* Check for possibility of overflow, in which case entry bb count | |
232 | is large enough to do the division first without losing much | |
233 | precision. */ | |
69ad6a32 | 234 | if (ENTRY_BLOCK_PTR_FOR_FN (fun)->count < REG_BR_PROB_BASE * |
34154e27 | 235 | REG_BR_PROB_BASE) |
c1acf60c | 236 | { |
237 | gcov_type scaled_count | |
69ad6a32 | 238 | = frequency * ENTRY_BLOCK_PTR_FOR_FN (fun)->count * |
34154e27 | 239 | unlikely_count_fraction; |
240 | computed_count = RDIV (scaled_count, | |
69ad6a32 | 241 | ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency); |
c1acf60c | 242 | } |
243 | else | |
244 | { | |
69ad6a32 | 245 | computed_count = RDIV (ENTRY_BLOCK_PTR_FOR_FN (fun)->count, |
246 | ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency); | |
c1acf60c | 247 | computed_count *= frequency * unlikely_count_fraction; |
248 | } | |
249 | if (computed_count >= profile_info->runs) | |
250 | return false; | |
4befb9f4 | 251 | } |
252 | return true; | |
253 | } | |
69ad6a32 | 254 | if ((!profile_info || !(opt_for_fn (fun->decl, flag_branch_probabilities))) |
415d1b9a | 255 | && (cgraph_node::get (fun->decl)->frequency |
fd6a3c41 | 256 | == NODE_FREQUENCY_UNLIKELY_EXECUTED)) |
5de92639 | 257 | return true; |
429fa7fa | 258 | return false; |
259 | } | |
260 | ||
80adc5a6 | 261 | |
dcc9b351 | 262 | /* Return true in case BB is probably never executed. */ |
263 | ||
264 | bool | |
265 | probably_never_executed_bb_p (struct function *fun, const_basic_block bb) | |
266 | { | |
267 | return probably_never_executed (fun, bb->count, bb->frequency); | |
268 | } | |
269 | ||
270 | ||
80adc5a6 | 271 | /* Return true in case edge E is probably never executed. */ |
272 | ||
273 | bool | |
274 | probably_never_executed_edge_p (struct function *fun, edge e) | |
429fa7fa | 275 | { |
dcc9b351 | 276 | return probably_never_executed (fun, e->count, EDGE_FREQUENCY (e)); |
429fa7fa | 277 | } |
278 | ||
cf262be9 | 279 | /* Return true when current function should always be optimized for size. */ |
280 | ||
281 | bool | |
282 | optimize_function_for_size_p (struct function *fun) | |
283 | { | |
cf262be9 | 284 | if (!fun || !fun->decl) |
69ad6a32 | 285 | return optimize_size; |
415d1b9a | 286 | cgraph_node *n = cgraph_node::get (fun->decl); |
287 | return n && n->optimize_for_size_p (); | |
cf262be9 | 288 | } |
289 | ||
533af0db | 290 | /* Return true when current function should always be optimized for speed. */ |
291 | ||
292 | bool | |
293 | optimize_function_for_speed_p (struct function *fun) | |
294 | { | |
295 | return !optimize_function_for_size_p (fun); | |
7dfb44a0 | 296 | } |
297 | ||
298 | /* Return TRUE when BB should be optimized for size. */ | |
299 | ||
300 | bool | |
94ba1cf1 | 301 | optimize_bb_for_size_p (const_basic_block bb) |
7dfb44a0 | 302 | { |
b9ea678c | 303 | return (optimize_function_for_size_p (cfun) |
304 | || (bb && !maybe_hot_bb_p (cfun, bb))); | |
7dfb44a0 | 305 | } |
306 | ||
307 | /* Return TRUE when BB should be optimized for speed. */ | |
308 | ||
309 | bool | |
94ba1cf1 | 310 | optimize_bb_for_speed_p (const_basic_block bb) |
7dfb44a0 | 311 | { |
312 | return !optimize_bb_for_size_p (bb); | |
313 | } | |
314 | ||
315 | /* Return TRUE when BB should be optimized for size. */ | |
316 | ||
317 | bool | |
318 | optimize_edge_for_size_p (edge e) | |
319 | { | |
533af0db | 320 | return optimize_function_for_size_p (cfun) || !maybe_hot_edge_p (e); |
7dfb44a0 | 321 | } |
322 | ||
323 | /* Return TRUE when BB should be optimized for speed. */ | |
324 | ||
325 | bool | |
326 | optimize_edge_for_speed_p (edge e) | |
327 | { | |
328 | return !optimize_edge_for_size_p (e); | |
329 | } | |
330 | ||
331 | /* Return TRUE when BB should be optimized for size. */ | |
332 | ||
333 | bool | |
334 | optimize_insn_for_size_p (void) | |
335 | { | |
533af0db | 336 | return optimize_function_for_size_p (cfun) || !crtl->maybe_hot_insn_p; |
7dfb44a0 | 337 | } |
338 | ||
339 | /* Return TRUE when BB should be optimized for speed. */ | |
340 | ||
341 | bool | |
342 | optimize_insn_for_speed_p (void) | |
343 | { | |
344 | return !optimize_insn_for_size_p (); | |
345 | } | |
346 | ||
94ba1cf1 | 347 | /* Return TRUE when LOOP should be optimized for size. */ |
348 | ||
349 | bool | |
350 | optimize_loop_for_size_p (struct loop *loop) | |
351 | { | |
352 | return optimize_bb_for_size_p (loop->header); | |
353 | } | |
354 | ||
355 | /* Return TRUE when LOOP should be optimized for speed. */ | |
356 | ||
357 | bool | |
358 | optimize_loop_for_speed_p (struct loop *loop) | |
359 | { | |
360 | return optimize_bb_for_speed_p (loop->header); | |
361 | } | |
362 | ||
0bfd8d5c | 363 | /* Return TRUE when LOOP nest should be optimized for speed. */ |
364 | ||
365 | bool | |
366 | optimize_loop_nest_for_speed_p (struct loop *loop) | |
367 | { | |
368 | struct loop *l = loop; | |
369 | if (optimize_loop_for_speed_p (loop)) | |
370 | return true; | |
371 | l = loop->inner; | |
53be41ae | 372 | while (l && l != loop) |
0bfd8d5c | 373 | { |
374 | if (optimize_loop_for_speed_p (l)) | |
375 | return true; | |
376 | if (l->inner) | |
377 | l = l->inner; | |
378 | else if (l->next) | |
379 | l = l->next; | |
380 | else | |
7baffbd3 | 381 | { |
382 | while (l != loop && !l->next) | |
383 | l = loop_outer (l); | |
384 | if (l != loop) | |
385 | l = l->next; | |
386 | } | |
0bfd8d5c | 387 | } |
388 | return false; | |
389 | } | |
390 | ||
391 | /* Return TRUE when LOOP nest should be optimized for size. */ | |
392 | ||
393 | bool | |
394 | optimize_loop_nest_for_size_p (struct loop *loop) | |
395 | { | |
396 | return !optimize_loop_nest_for_speed_p (loop); | |
397 | } | |
398 | ||
4a9d7ef7 | 399 | /* Return true when edge E is likely to be well predictable by branch |
400 | predictor. */ | |
401 | ||
402 | bool | |
403 | predictable_edge_p (edge e) | |
404 | { | |
f26d8580 | 405 | if (profile_status_for_fn (cfun) == PROFILE_ABSENT) |
4a9d7ef7 | 406 | return false; |
407 | if ((e->probability | |
408 | <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100) | |
409 | || (REG_BR_PROB_BASE - e->probability | |
410 | <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100)) | |
411 | return true; | |
412 | return false; | |
413 | } | |
414 | ||
415 | ||
7dfb44a0 | 416 | /* Set RTL expansion for BB profile. */ |
417 | ||
418 | void | |
419 | rtl_profile_for_bb (basic_block bb) | |
420 | { | |
8d672d12 | 421 | crtl->maybe_hot_insn_p = maybe_hot_bb_p (cfun, bb); |
7dfb44a0 | 422 | } |
423 | ||
424 | /* Set RTL expansion for edge profile. */ | |
425 | ||
426 | void | |
427 | rtl_profile_for_edge (edge e) | |
428 | { | |
429 | crtl->maybe_hot_insn_p = maybe_hot_edge_p (e); | |
430 | } | |
431 | ||
432 | /* Set RTL expansion to default mode (i.e. when profile info is not known). */ | |
433 | void | |
434 | default_rtl_profile (void) | |
435 | { | |
436 | crtl->maybe_hot_insn_p = true; | |
437 | } | |
438 | ||
cd0fe062 | 439 | /* Return true if the one of outgoing edges is already predicted by |
440 | PREDICTOR. */ | |
441 | ||
4ee9c684 | 442 | bool |
5493cb9a | 443 | rtl_predicted_by_p (const_basic_block bb, enum br_predictor predictor) |
cd0fe062 | 444 | { |
445 | rtx note; | |
5496dbfc | 446 | if (!INSN_P (BB_END (bb))) |
cd0fe062 | 447 | return false; |
5496dbfc | 448 | for (note = REG_NOTES (BB_END (bb)); note; note = XEXP (note, 1)) |
cd0fe062 | 449 | if (REG_NOTE_KIND (note) == REG_BR_PRED |
450 | && INTVAL (XEXP (XEXP (note, 0), 0)) == (int)predictor) | |
451 | return true; | |
452 | return false; | |
453 | } | |
5e96f51e | 454 | |
eeb030c4 | 455 | /* Structure representing predictions in tree level. */ |
456 | ||
457 | struct edge_prediction { | |
458 | struct edge_prediction *ep_next; | |
459 | edge ep_edge; | |
460 | enum br_predictor ep_predictor; | |
461 | int ep_probability; | |
462 | }; | |
463 | ||
06ecf488 | 464 | /* This map contains for a basic block the list of predictions for the |
465 | outgoing edges. */ | |
466 | ||
467 | static hash_map<const_basic_block, edge_prediction *> *bb_predictions; | |
468 | ||
4ee9c684 | 469 | /* Return true if the one of outgoing edges is already predicted by |
470 | PREDICTOR. */ | |
471 | ||
472 | bool | |
75a70cf9 | 473 | gimple_predicted_by_p (const_basic_block bb, enum br_predictor predictor) |
4ee9c684 | 474 | { |
7ea47fbd | 475 | struct edge_prediction *i; |
06ecf488 | 476 | edge_prediction **preds = bb_predictions->get (bb); |
b3723726 | 477 | |
478 | if (!preds) | |
479 | return false; | |
48e1416a | 480 | |
06ecf488 | 481 | for (i = *preds; i; i = i->ep_next) |
f45e9182 | 482 | if (i->ep_predictor == predictor) |
4ee9c684 | 483 | return true; |
484 | return false; | |
485 | } | |
486 | ||
b41438e5 | 487 | /* Return true when the probability of edge is reliable. |
48e1416a | 488 | |
b41438e5 | 489 | The profile guessing code is good at predicting branch outcome (ie. |
490 | taken/not taken), that is predicted right slightly over 75% of time. | |
ab4f0a13 | 491 | It is however notoriously poor on predicting the probability itself. |
b41438e5 | 492 | In general the profile appear a lot flatter (with probabilities closer |
493 | to 50%) than the reality so it is bad idea to use it to drive optimization | |
494 | such as those disabling dynamic branch prediction for well predictable | |
495 | branches. | |
496 | ||
497 | There are two exceptions - edges leading to noreturn edges and edges | |
498 | predicted by number of iterations heuristics are predicted well. This macro | |
499 | should be able to distinguish those, but at the moment it simply check for | |
500 | noreturn heuristic that is only one giving probability over 99% or bellow | |
ab4f0a13 | 501 | 1%. In future we might want to propagate reliability information across the |
b41438e5 | 502 | CFG if we find this information useful on multiple places. */ |
503 | static bool | |
504 | probability_reliable_p (int prob) | |
505 | { | |
f26d8580 | 506 | return (profile_status_for_fn (cfun) == PROFILE_READ |
507 | || (profile_status_for_fn (cfun) == PROFILE_GUESSED | |
b41438e5 | 508 | && (prob <= HITRATE (1) || prob >= HITRATE (99)))); |
509 | } | |
510 | ||
511 | /* Same predicate as above, working on edges. */ | |
512 | bool | |
7ecb5bb2 | 513 | edge_probability_reliable_p (const_edge e) |
b41438e5 | 514 | { |
515 | return probability_reliable_p (e->probability); | |
516 | } | |
517 | ||
518 | /* Same predicate as edge_probability_reliable_p, working on notes. */ | |
519 | bool | |
7ecb5bb2 | 520 | br_prob_note_reliable_p (const_rtx note) |
b41438e5 | 521 | { |
522 | gcc_assert (REG_NOTE_KIND (note) == REG_BR_PROB); | |
9eb946de | 523 | return probability_reliable_p (XINT (note, 0)); |
b41438e5 | 524 | } |
525 | ||
aa157ca4 | 526 | static void |
ee5f6585 | 527 | predict_insn (rtx_insn *insn, enum br_predictor predictor, int probability) |
13488c51 | 528 | { |
876760f6 | 529 | gcc_assert (any_condjump_p (insn)); |
b28bedce | 530 | if (!flag_guess_branch_prob) |
531 | return; | |
e6751e9a | 532 | |
a1ddb869 | 533 | add_reg_note (insn, REG_BR_PRED, |
534 | gen_rtx_CONCAT (VOIDmode, | |
535 | GEN_INT ((int) predictor), | |
536 | GEN_INT ((int) probability))); | |
13488c51 | 537 | } |
538 | ||
539 | /* Predict insn by given predictor. */ | |
e6751e9a | 540 | |
13488c51 | 541 | void |
ee5f6585 | 542 | predict_insn_def (rtx_insn *insn, enum br_predictor predictor, |
d598ad0d | 543 | enum prediction taken) |
13488c51 | 544 | { |
545 | int probability = predictor_info[(int) predictor].hitrate; | |
e6751e9a | 546 | |
13488c51 | 547 | if (taken != TAKEN) |
548 | probability = REG_BR_PROB_BASE - probability; | |
e6751e9a | 549 | |
13488c51 | 550 | predict_insn (insn, predictor, probability); |
5e96f51e | 551 | } |
552 | ||
553 | /* Predict edge E with given probability if possible. */ | |
e6751e9a | 554 | |
13488c51 | 555 | void |
4ee9c684 | 556 | rtl_predict_edge (edge e, enum br_predictor predictor, int probability) |
5e96f51e | 557 | { |
ee5f6585 | 558 | rtx_insn *last_insn; |
5496dbfc | 559 | last_insn = BB_END (e->src); |
5e96f51e | 560 | |
561 | /* We can store the branch prediction information only about | |
562 | conditional jumps. */ | |
563 | if (!any_condjump_p (last_insn)) | |
564 | return; | |
565 | ||
566 | /* We always store probability of branching. */ | |
567 | if (e->flags & EDGE_FALLTHRU) | |
568 | probability = REG_BR_PROB_BASE - probability; | |
569 | ||
13488c51 | 570 | predict_insn (last_insn, predictor, probability); |
571 | } | |
572 | ||
4ee9c684 | 573 | /* Predict edge E with the given PROBABILITY. */ |
574 | void | |
75a70cf9 | 575 | gimple_predict_edge (edge e, enum br_predictor predictor, int probability) |
4ee9c684 | 576 | { |
f26d8580 | 577 | gcc_assert (profile_status_for_fn (cfun) != PROFILE_GUESSED); |
34154e27 | 578 | if ((e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun) && EDGE_COUNT (e->src->succs) > |
579 | 1) | |
d5043f32 | 580 | && flag_guess_branch_prob && optimize) |
ebd65d12 | 581 | { |
b3723726 | 582 | struct edge_prediction *i = XNEW (struct edge_prediction); |
06ecf488 | 583 | edge_prediction *&preds = bb_predictions->get_or_insert (e->src); |
4ee9c684 | 584 | |
06ecf488 | 585 | i->ep_next = preds; |
586 | preds = i; | |
f45e9182 | 587 | i->ep_probability = probability; |
588 | i->ep_predictor = predictor; | |
589 | i->ep_edge = e; | |
ebd65d12 | 590 | } |
4ee9c684 | 591 | } |
592 | ||
631fa7de | 593 | /* Remove all predictions on given basic block that are attached |
594 | to edge E. */ | |
595 | void | |
596 | remove_predictions_associated_with_edge (edge e) | |
597 | { | |
b3723726 | 598 | if (!bb_predictions) |
599 | return; | |
600 | ||
06ecf488 | 601 | edge_prediction **preds = bb_predictions->get (e->src); |
b3723726 | 602 | |
603 | if (preds) | |
631fa7de | 604 | { |
06ecf488 | 605 | struct edge_prediction **prediction = preds; |
b3723726 | 606 | struct edge_prediction *next; |
607 | ||
631fa7de | 608 | while (*prediction) |
609 | { | |
f45e9182 | 610 | if ((*prediction)->ep_edge == e) |
b3723726 | 611 | { |
612 | next = (*prediction)->ep_next; | |
613 | free (*prediction); | |
614 | *prediction = next; | |
615 | } | |
631fa7de | 616 | else |
f45e9182 | 617 | prediction = &((*prediction)->ep_next); |
631fa7de | 618 | } |
619 | } | |
620 | } | |
621 | ||
b3723726 | 622 | /* Clears the list of predictions stored for BB. */ |
623 | ||
624 | static void | |
625 | clear_bb_predictions (basic_block bb) | |
626 | { | |
06ecf488 | 627 | edge_prediction **preds = bb_predictions->get (bb); |
b3723726 | 628 | struct edge_prediction *pred, *next; |
629 | ||
630 | if (!preds) | |
631 | return; | |
632 | ||
06ecf488 | 633 | for (pred = *preds; pred; pred = next) |
b3723726 | 634 | { |
635 | next = pred->ep_next; | |
636 | free (pred); | |
637 | } | |
638 | *preds = NULL; | |
639 | } | |
640 | ||
1a12dac4 | 641 | /* Return true when we can store prediction on insn INSN. |
642 | At the moment we represent predictions only on conditional | |
643 | jumps, not at computed jump or other complicated cases. */ | |
644 | static bool | |
ee5f6585 | 645 | can_predict_insn_p (const rtx_insn *insn) |
1a12dac4 | 646 | { |
6d7dc5b9 | 647 | return (JUMP_P (insn) |
1a12dac4 | 648 | && any_condjump_p (insn) |
cd665a06 | 649 | && EDGE_COUNT (BLOCK_FOR_INSN (insn)->succs) >= 2); |
1a12dac4 | 650 | } |
651 | ||
13488c51 | 652 | /* Predict edge E by given predictor if possible. */ |
e6751e9a | 653 | |
13488c51 | 654 | void |
d598ad0d | 655 | predict_edge_def (edge e, enum br_predictor predictor, |
656 | enum prediction taken) | |
13488c51 | 657 | { |
658 | int probability = predictor_info[(int) predictor].hitrate; | |
659 | ||
660 | if (taken != TAKEN) | |
661 | probability = REG_BR_PROB_BASE - probability; | |
e6751e9a | 662 | |
13488c51 | 663 | predict_edge (e, predictor, probability); |
664 | } | |
665 | ||
666 | /* Invert all branch predictions or probability notes in the INSN. This needs | |
667 | to be done each time we invert the condition used by the jump. */ | |
e6751e9a | 668 | |
13488c51 | 669 | void |
d598ad0d | 670 | invert_br_probabilities (rtx insn) |
13488c51 | 671 | { |
e6751e9a | 672 | rtx note; |
673 | ||
674 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) | |
675 | if (REG_NOTE_KIND (note) == REG_BR_PROB) | |
9eb946de | 676 | XINT (note, 0) = REG_BR_PROB_BASE - XINT (note, 0); |
e6751e9a | 677 | else if (REG_NOTE_KIND (note) == REG_BR_PRED) |
678 | XEXP (XEXP (note, 0), 1) | |
679 | = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (XEXP (note, 0), 1))); | |
13488c51 | 680 | } |
681 | ||
682 | /* Dump information about the branch prediction to the output file. */ | |
e6751e9a | 683 | |
13488c51 | 684 | static void |
4ee9c684 | 685 | dump_prediction (FILE *file, enum br_predictor predictor, int probability, |
d598ad0d | 686 | basic_block bb, int used) |
13488c51 | 687 | { |
cd665a06 | 688 | edge e; |
689 | edge_iterator ei; | |
13488c51 | 690 | |
4ee9c684 | 691 | if (!file) |
13488c51 | 692 | return; |
693 | ||
cd665a06 | 694 | FOR_EACH_EDGE (e, ei, bb->succs) |
695 | if (! (e->flags & EDGE_FALLTHRU)) | |
696 | break; | |
13488c51 | 697 | |
4ee9c684 | 698 | fprintf (file, " %s heuristics%s: %.1f%%", |
13488c51 | 699 | predictor_info[predictor].name, |
e6751e9a | 700 | used ? "" : " (ignored)", probability * 100.0 / REG_BR_PROB_BASE); |
13488c51 | 701 | |
702 | if (bb->count) | |
17a81216 | 703 | { |
f03df321 | 704 | fprintf (file, " exec %" PRId64, bb->count); |
12c94d25 | 705 | if (e) |
706 | { | |
f03df321 | 707 | fprintf (file, " hit %" PRId64, e->count); |
4ee9c684 | 708 | fprintf (file, " (%.1f%%)", e->count * 100.0 / bb->count); |
12c94d25 | 709 | } |
17a81216 | 710 | } |
e6751e9a | 711 | |
4ee9c684 | 712 | fprintf (file, "\n"); |
13488c51 | 713 | } |
714 | ||
7edd21a5 | 715 | /* We can not predict the probabilities of outgoing edges of bb. Set them |
83c8a977 | 716 | evenly and hope for the best. */ |
717 | static void | |
718 | set_even_probabilities (basic_block bb) | |
719 | { | |
720 | int nedges = 0; | |
721 | edge e; | |
cd665a06 | 722 | edge_iterator ei; |
83c8a977 | 723 | |
cd665a06 | 724 | FOR_EACH_EDGE (e, ei, bb->succs) |
83c8a977 | 725 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
726 | nedges ++; | |
cd665a06 | 727 | FOR_EACH_EDGE (e, ei, bb->succs) |
83c8a977 | 728 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
729 | e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges; | |
730 | else | |
731 | e->probability = 0; | |
732 | } | |
733 | ||
13488c51 | 734 | /* Combine all REG_BR_PRED notes into single probability and attach REG_BR_PROB |
735 | note if not already present. Remove now useless REG_BR_PRED notes. */ | |
e6751e9a | 736 | |
13488c51 | 737 | static void |
ee5f6585 | 738 | combine_predictions_for_insn (rtx_insn *insn, basic_block bb) |
13488c51 | 739 | { |
83c8a977 | 740 | rtx prob_note; |
741 | rtx *pnote; | |
e6751e9a | 742 | rtx note; |
13488c51 | 743 | int best_probability = PROB_EVEN; |
b9c74b4d | 744 | enum br_predictor best_predictor = END_PREDICTORS; |
eb429644 | 745 | int combined_probability = REG_BR_PROB_BASE / 2; |
746 | int d; | |
49d7c0db | 747 | bool first_match = false; |
748 | bool found = false; | |
13488c51 | 749 | |
83c8a977 | 750 | if (!can_predict_insn_p (insn)) |
751 | { | |
752 | set_even_probabilities (bb); | |
753 | return; | |
754 | } | |
755 | ||
756 | prob_note = find_reg_note (insn, REG_BR_PROB, 0); | |
757 | pnote = ®_NOTES (insn); | |
450d042a | 758 | if (dump_file) |
759 | fprintf (dump_file, "Predictions for insn %i bb %i\n", INSN_UID (insn), | |
b3d6de89 | 760 | bb->index); |
13488c51 | 761 | |
762 | /* We implement "first match" heuristics and use probability guessed | |
4ee9c684 | 763 | by predictor with smallest index. */ |
e6751e9a | 764 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) |
765 | if (REG_NOTE_KIND (note) == REG_BR_PRED) | |
766 | { | |
bc620c5c | 767 | enum br_predictor predictor = ((enum br_predictor) |
768 | INTVAL (XEXP (XEXP (note, 0), 0))); | |
e6751e9a | 769 | int probability = INTVAL (XEXP (XEXP (note, 0), 1)); |
770 | ||
771 | found = true; | |
772 | if (best_predictor > predictor) | |
773 | best_probability = probability, best_predictor = predictor; | |
774 | ||
775 | d = (combined_probability * probability | |
776 | + (REG_BR_PROB_BASE - combined_probability) | |
777 | * (REG_BR_PROB_BASE - probability)); | |
778 | ||
779 | /* Use FP math to avoid overflows of 32bit integers. */ | |
c4a616f2 | 780 | if (d == 0) |
781 | /* If one probability is 0% and one 100%, avoid division by zero. */ | |
782 | combined_probability = REG_BR_PROB_BASE / 2; | |
783 | else | |
784 | combined_probability = (((double) combined_probability) * probability | |
785 | * REG_BR_PROB_BASE / d + 0.5); | |
e6751e9a | 786 | } |
787 | ||
788 | /* Decide which heuristic to use. In case we didn't match anything, | |
789 | use no_prediction heuristic, in case we did match, use either | |
49d7c0db | 790 | first match or Dempster-Shaffer theory depending on the flags. */ |
791 | ||
eb429644 | 792 | if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH) |
49d7c0db | 793 | first_match = true; |
794 | ||
795 | if (!found) | |
4ee9c684 | 796 | dump_prediction (dump_file, PRED_NO_PREDICTION, |
797 | combined_probability, bb, true); | |
49d7c0db | 798 | else |
799 | { | |
4ee9c684 | 800 | dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, |
801 | bb, !first_match); | |
802 | dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, | |
803 | bb, first_match); | |
49d7c0db | 804 | } |
805 | ||
806 | if (first_match) | |
eb429644 | 807 | combined_probability = best_probability; |
4ee9c684 | 808 | dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); |
49d7c0db | 809 | |
810 | while (*pnote) | |
811 | { | |
812 | if (REG_NOTE_KIND (*pnote) == REG_BR_PRED) | |
813 | { | |
bc620c5c | 814 | enum br_predictor predictor = ((enum br_predictor) |
815 | INTVAL (XEXP (XEXP (*pnote, 0), 0))); | |
49d7c0db | 816 | int probability = INTVAL (XEXP (XEXP (*pnote, 0), 1)); |
817 | ||
4ee9c684 | 818 | dump_prediction (dump_file, predictor, probability, bb, |
49d7c0db | 819 | !first_match || best_predictor == predictor); |
195731ad | 820 | *pnote = XEXP (*pnote, 1); |
49d7c0db | 821 | } |
822 | else | |
195731ad | 823 | pnote = &XEXP (*pnote, 1); |
49d7c0db | 824 | } |
e6751e9a | 825 | |
13488c51 | 826 | if (!prob_note) |
827 | { | |
9eb946de | 828 | add_int_reg_note (insn, REG_BR_PROB, combined_probability); |
e6751e9a | 829 | |
eb429644 | 830 | /* Save the prediction into CFG in case we are seeing non-degenerated |
831 | conditional jump. */ | |
ea091dfd | 832 | if (!single_succ_p (bb)) |
eb429644 | 833 | { |
834 | BRANCH_EDGE (bb)->probability = combined_probability; | |
e6751e9a | 835 | FALLTHRU_EDGE (bb)->probability |
836 | = REG_BR_PROB_BASE - combined_probability; | |
eb429644 | 837 | } |
13488c51 | 838 | } |
ea091dfd | 839 | else if (!single_succ_p (bb)) |
d8c70625 | 840 | { |
9eb946de | 841 | int prob = XINT (prob_note, 0); |
d8c70625 | 842 | |
843 | BRANCH_EDGE (bb)->probability = prob; | |
844 | FALLTHRU_EDGE (bb)->probability = REG_BR_PROB_BASE - prob; | |
845 | } | |
846 | else | |
ea091dfd | 847 | single_succ_edge (bb)->probability = REG_BR_PROB_BASE; |
5e96f51e | 848 | } |
849 | ||
4ee9c684 | 850 | /* Combine predictions into single probability and store them into CFG. |
851 | Remove now useless prediction entries. */ | |
59423b59 | 852 | |
4ee9c684 | 853 | static void |
3f5be5f4 | 854 | combine_predictions_for_bb (basic_block bb) |
59423b59 | 855 | { |
4ee9c684 | 856 | int best_probability = PROB_EVEN; |
b9c74b4d | 857 | enum br_predictor best_predictor = END_PREDICTORS; |
4ee9c684 | 858 | int combined_probability = REG_BR_PROB_BASE / 2; |
859 | int d; | |
860 | bool first_match = false; | |
861 | bool found = false; | |
862 | struct edge_prediction *pred; | |
863 | int nedges = 0; | |
864 | edge e, first = NULL, second = NULL; | |
cd665a06 | 865 | edge_iterator ei; |
59423b59 | 866 | |
cd665a06 | 867 | FOR_EACH_EDGE (e, ei, bb->succs) |
4ee9c684 | 868 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
869 | { | |
cd665a06 | 870 | nedges ++; |
4ee9c684 | 871 | if (first && !second) |
872 | second = e; | |
873 | if (!first) | |
874 | first = e; | |
875 | } | |
876 | ||
48e1416a | 877 | /* When there is no successor or only one choice, prediction is easy. |
4ee9c684 | 878 | |
879 | We are lazy for now and predict only basic blocks with two outgoing | |
880 | edges. It is possible to predict generic case too, but we have to | |
881 | ignore first match heuristics and do more involved combining. Implement | |
882 | this later. */ | |
883 | if (nedges != 2) | |
884 | { | |
83c8a977 | 885 | if (!bb->count) |
886 | set_even_probabilities (bb); | |
b3723726 | 887 | clear_bb_predictions (bb); |
3f5be5f4 | 888 | if (dump_file) |
889 | fprintf (dump_file, "%i edges in bb %i predicted to even probabilities\n", | |
4ee9c684 | 890 | nedges, bb->index); |
891 | return; | |
892 | } | |
893 | ||
3f5be5f4 | 894 | if (dump_file) |
895 | fprintf (dump_file, "Predictions for bb %i\n", bb->index); | |
4ee9c684 | 896 | |
06ecf488 | 897 | edge_prediction **preds = bb_predictions->get (bb); |
b3723726 | 898 | if (preds) |
4ee9c684 | 899 | { |
b3723726 | 900 | /* We implement "first match" heuristics and use probability guessed |
901 | by predictor with smallest index. */ | |
06ecf488 | 902 | for (pred = *preds; pred; pred = pred->ep_next) |
b3723726 | 903 | { |
b9c74b4d | 904 | enum br_predictor predictor = pred->ep_predictor; |
b3723726 | 905 | int probability = pred->ep_probability; |
4ee9c684 | 906 | |
b3723726 | 907 | if (pred->ep_edge != first) |
908 | probability = REG_BR_PROB_BASE - probability; | |
4ee9c684 | 909 | |
b3723726 | 910 | found = true; |
9f694a82 | 911 | /* First match heuristics would be widly confused if we predicted |
912 | both directions. */ | |
b3723726 | 913 | if (best_predictor > predictor) |
9f694a82 | 914 | { |
915 | struct edge_prediction *pred2; | |
916 | int prob = probability; | |
917 | ||
c83059be | 918 | for (pred2 = (struct edge_prediction *) *preds; |
919 | pred2; pred2 = pred2->ep_next) | |
9f694a82 | 920 | if (pred2 != pred && pred2->ep_predictor == pred->ep_predictor) |
921 | { | |
922 | int probability2 = pred->ep_probability; | |
923 | ||
924 | if (pred2->ep_edge != first) | |
925 | probability2 = REG_BR_PROB_BASE - probability2; | |
926 | ||
48e1416a | 927 | if ((probability < REG_BR_PROB_BASE / 2) != |
9f694a82 | 928 | (probability2 < REG_BR_PROB_BASE / 2)) |
929 | break; | |
930 | ||
931 | /* If the same predictor later gave better result, go for it! */ | |
932 | if ((probability >= REG_BR_PROB_BASE / 2 && (probability2 > probability)) | |
933 | || (probability <= REG_BR_PROB_BASE / 2 && (probability2 < probability))) | |
934 | prob = probability2; | |
935 | } | |
936 | if (!pred2) | |
937 | best_probability = prob, best_predictor = predictor; | |
938 | } | |
4ee9c684 | 939 | |
b3723726 | 940 | d = (combined_probability * probability |
941 | + (REG_BR_PROB_BASE - combined_probability) | |
942 | * (REG_BR_PROB_BASE - probability)); | |
4ee9c684 | 943 | |
b3723726 | 944 | /* Use FP math to avoid overflows of 32bit integers. */ |
945 | if (d == 0) | |
946 | /* If one probability is 0% and one 100%, avoid division by zero. */ | |
947 | combined_probability = REG_BR_PROB_BASE / 2; | |
948 | else | |
949 | combined_probability = (((double) combined_probability) | |
950 | * probability | |
951 | * REG_BR_PROB_BASE / d + 0.5); | |
952 | } | |
4ee9c684 | 953 | } |
954 | ||
955 | /* Decide which heuristic to use. In case we didn't match anything, | |
956 | use no_prediction heuristic, in case we did match, use either | |
957 | first match or Dempster-Shaffer theory depending on the flags. */ | |
958 | ||
959 | if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH) | |
960 | first_match = true; | |
961 | ||
962 | if (!found) | |
3f5be5f4 | 963 | dump_prediction (dump_file, PRED_NO_PREDICTION, combined_probability, bb, true); |
4ee9c684 | 964 | else |
965 | { | |
3f5be5f4 | 966 | dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, bb, |
4ee9c684 | 967 | !first_match); |
3f5be5f4 | 968 | dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, bb, |
4ee9c684 | 969 | first_match); |
970 | } | |
971 | ||
972 | if (first_match) | |
973 | combined_probability = best_probability; | |
3f5be5f4 | 974 | dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); |
4ee9c684 | 975 | |
b3723726 | 976 | if (preds) |
4ee9c684 | 977 | { |
4077bf7a | 978 | for (pred = (struct edge_prediction *) *preds; pred; pred = pred->ep_next) |
b3723726 | 979 | { |
b9c74b4d | 980 | enum br_predictor predictor = pred->ep_predictor; |
b3723726 | 981 | int probability = pred->ep_probability; |
4ee9c684 | 982 | |
b3723726 | 983 | if (pred->ep_edge != EDGE_SUCC (bb, 0)) |
984 | probability = REG_BR_PROB_BASE - probability; | |
985 | dump_prediction (dump_file, predictor, probability, bb, | |
986 | !first_match || best_predictor == predictor); | |
987 | } | |
4ee9c684 | 988 | } |
b3723726 | 989 | clear_bb_predictions (bb); |
4ee9c684 | 990 | |
83c8a977 | 991 | if (!bb->count) |
992 | { | |
993 | first->probability = combined_probability; | |
994 | second->probability = REG_BR_PROB_BASE - combined_probability; | |
995 | } | |
4ee9c684 | 996 | } |
997 | ||
fd757b76 | 998 | /* Check if T1 and T2 satisfy the IV_COMPARE condition. |
999 | Return the SSA_NAME if the condition satisfies, NULL otherwise. | |
1000 | ||
1001 | T1 and T2 should be one of the following cases: | |
1002 | 1. T1 is SSA_NAME, T2 is NULL | |
1003 | 2. T1 is SSA_NAME, T2 is INTEGER_CST between [-4, 4] | |
1004 | 3. T2 is SSA_NAME, T1 is INTEGER_CST between [-4, 4] */ | |
1005 | ||
1006 | static tree | |
1007 | strips_small_constant (tree t1, tree t2) | |
1008 | { | |
1009 | tree ret = NULL; | |
1010 | int value = 0; | |
1011 | ||
1012 | if (!t1) | |
1013 | return NULL; | |
1014 | else if (TREE_CODE (t1) == SSA_NAME) | |
1015 | ret = t1; | |
e913b5cd | 1016 | else if (tree_fits_shwi_p (t1)) |
1017 | value = tree_to_shwi (t1); | |
fd757b76 | 1018 | else |
1019 | return NULL; | |
1020 | ||
1021 | if (!t2) | |
1022 | return ret; | |
e913b5cd | 1023 | else if (tree_fits_shwi_p (t2)) |
1024 | value = tree_to_shwi (t2); | |
fd757b76 | 1025 | else if (TREE_CODE (t2) == SSA_NAME) |
1026 | { | |
1027 | if (ret) | |
1028 | return NULL; | |
1029 | else | |
1030 | ret = t2; | |
1031 | } | |
1032 | ||
1033 | if (value <= 4 && value >= -4) | |
1034 | return ret; | |
1035 | else | |
1036 | return NULL; | |
1037 | } | |
1038 | ||
1039 | /* Return the SSA_NAME in T or T's operands. | |
1040 | Return NULL if SSA_NAME cannot be found. */ | |
1041 | ||
1042 | static tree | |
1043 | get_base_value (tree t) | |
1044 | { | |
1045 | if (TREE_CODE (t) == SSA_NAME) | |
1046 | return t; | |
1047 | ||
1048 | if (!BINARY_CLASS_P (t)) | |
1049 | return NULL; | |
1050 | ||
1051 | switch (TREE_OPERAND_LENGTH (t)) | |
1052 | { | |
1053 | case 1: | |
1054 | return strips_small_constant (TREE_OPERAND (t, 0), NULL); | |
1055 | case 2: | |
1056 | return strips_small_constant (TREE_OPERAND (t, 0), | |
1057 | TREE_OPERAND (t, 1)); | |
1058 | default: | |
1059 | return NULL; | |
1060 | } | |
1061 | } | |
1062 | ||
1063 | /* Check the compare STMT in LOOP. If it compares an induction | |
1064 | variable to a loop invariant, return true, and save | |
1065 | LOOP_INVARIANT, COMPARE_CODE and LOOP_STEP. | |
1066 | Otherwise return false and set LOOP_INVAIANT to NULL. */ | |
1067 | ||
1068 | static bool | |
1a91d914 | 1069 | is_comparison_with_loop_invariant_p (gcond *stmt, struct loop *loop, |
fd757b76 | 1070 | tree *loop_invariant, |
1071 | enum tree_code *compare_code, | |
b3269f54 | 1072 | tree *loop_step, |
fd757b76 | 1073 | tree *loop_iv_base) |
1074 | { | |
1075 | tree op0, op1, bound, base; | |
1076 | affine_iv iv0, iv1; | |
1077 | enum tree_code code; | |
b3269f54 | 1078 | tree step; |
fd757b76 | 1079 | |
1080 | code = gimple_cond_code (stmt); | |
1081 | *loop_invariant = NULL; | |
1082 | ||
1083 | switch (code) | |
1084 | { | |
1085 | case GT_EXPR: | |
1086 | case GE_EXPR: | |
1087 | case NE_EXPR: | |
1088 | case LT_EXPR: | |
1089 | case LE_EXPR: | |
1090 | case EQ_EXPR: | |
1091 | break; | |
1092 | ||
1093 | default: | |
1094 | return false; | |
1095 | } | |
1096 | ||
1097 | op0 = gimple_cond_lhs (stmt); | |
1098 | op1 = gimple_cond_rhs (stmt); | |
1099 | ||
1100 | if ((TREE_CODE (op0) != SSA_NAME && TREE_CODE (op0) != INTEGER_CST) | |
1101 | || (TREE_CODE (op1) != SSA_NAME && TREE_CODE (op1) != INTEGER_CST)) | |
1102 | return false; | |
1103 | if (!simple_iv (loop, loop_containing_stmt (stmt), op0, &iv0, true)) | |
1104 | return false; | |
1105 | if (!simple_iv (loop, loop_containing_stmt (stmt), op1, &iv1, true)) | |
1106 | return false; | |
1107 | if (TREE_CODE (iv0.step) != INTEGER_CST | |
1108 | || TREE_CODE (iv1.step) != INTEGER_CST) | |
1109 | return false; | |
1110 | if ((integer_zerop (iv0.step) && integer_zerop (iv1.step)) | |
1111 | || (!integer_zerop (iv0.step) && !integer_zerop (iv1.step))) | |
1112 | return false; | |
1113 | ||
1114 | if (integer_zerop (iv0.step)) | |
1115 | { | |
1116 | if (code != NE_EXPR && code != EQ_EXPR) | |
1117 | code = invert_tree_comparison (code, false); | |
1118 | bound = iv0.base; | |
1119 | base = iv1.base; | |
e913b5cd | 1120 | if (tree_fits_shwi_p (iv1.step)) |
b3269f54 | 1121 | step = iv1.step; |
fd757b76 | 1122 | else |
1123 | return false; | |
1124 | } | |
1125 | else | |
1126 | { | |
1127 | bound = iv1.base; | |
1128 | base = iv0.base; | |
e913b5cd | 1129 | if (tree_fits_shwi_p (iv0.step)) |
b3269f54 | 1130 | step = iv0.step; |
fd757b76 | 1131 | else |
1132 | return false; | |
1133 | } | |
1134 | ||
1135 | if (TREE_CODE (bound) != INTEGER_CST) | |
1136 | bound = get_base_value (bound); | |
1137 | if (!bound) | |
1138 | return false; | |
1139 | if (TREE_CODE (base) != INTEGER_CST) | |
1140 | base = get_base_value (base); | |
1141 | if (!base) | |
1142 | return false; | |
1143 | ||
1144 | *loop_invariant = bound; | |
1145 | *compare_code = code; | |
1146 | *loop_step = step; | |
1147 | *loop_iv_base = base; | |
1148 | return true; | |
1149 | } | |
1150 | ||
1151 | /* Compare two SSA_NAMEs: returns TRUE if T1 and T2 are value coherent. */ | |
1152 | ||
1153 | static bool | |
1154 | expr_coherent_p (tree t1, tree t2) | |
1155 | { | |
1156 | gimple stmt; | |
1157 | tree ssa_name_1 = NULL; | |
1158 | tree ssa_name_2 = NULL; | |
1159 | ||
1160 | gcc_assert (TREE_CODE (t1) == SSA_NAME || TREE_CODE (t1) == INTEGER_CST); | |
1161 | gcc_assert (TREE_CODE (t2) == SSA_NAME || TREE_CODE (t2) == INTEGER_CST); | |
1162 | ||
1163 | if (t1 == t2) | |
1164 | return true; | |
1165 | ||
1166 | if (TREE_CODE (t1) == INTEGER_CST && TREE_CODE (t2) == INTEGER_CST) | |
1167 | return true; | |
1168 | if (TREE_CODE (t1) == INTEGER_CST || TREE_CODE (t2) == INTEGER_CST) | |
1169 | return false; | |
1170 | ||
1171 | /* Check to see if t1 is expressed/defined with t2. */ | |
1172 | stmt = SSA_NAME_DEF_STMT (t1); | |
1173 | gcc_assert (stmt != NULL); | |
1174 | if (is_gimple_assign (stmt)) | |
1175 | { | |
1176 | ssa_name_1 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); | |
1177 | if (ssa_name_1 && ssa_name_1 == t2) | |
1178 | return true; | |
1179 | } | |
1180 | ||
1181 | /* Check to see if t2 is expressed/defined with t1. */ | |
1182 | stmt = SSA_NAME_DEF_STMT (t2); | |
1183 | gcc_assert (stmt != NULL); | |
1184 | if (is_gimple_assign (stmt)) | |
1185 | { | |
1186 | ssa_name_2 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); | |
1187 | if (ssa_name_2 && ssa_name_2 == t1) | |
1188 | return true; | |
1189 | } | |
1190 | ||
1191 | /* Compare if t1 and t2's def_stmts are identical. */ | |
1192 | if (ssa_name_2 != NULL && ssa_name_1 == ssa_name_2) | |
1193 | return true; | |
1194 | else | |
1195 | return false; | |
1196 | } | |
1197 | ||
1198 | /* Predict branch probability of BB when BB contains a branch that compares | |
1199 | an induction variable in LOOP with LOOP_IV_BASE_VAR to LOOP_BOUND_VAR. The | |
1200 | loop exit is compared using LOOP_BOUND_CODE, with step of LOOP_BOUND_STEP. | |
1201 | ||
1202 | E.g. | |
1203 | for (int i = 0; i < bound; i++) { | |
1204 | if (i < bound - 2) | |
1205 | computation_1(); | |
1206 | else | |
1207 | computation_2(); | |
1208 | } | |
1209 | ||
1210 | In this loop, we will predict the branch inside the loop to be taken. */ | |
1211 | ||
1212 | static void | |
1213 | predict_iv_comparison (struct loop *loop, basic_block bb, | |
1214 | tree loop_bound_var, | |
1215 | tree loop_iv_base_var, | |
1216 | enum tree_code loop_bound_code, | |
1217 | int loop_bound_step) | |
1218 | { | |
1219 | gimple stmt; | |
1220 | tree compare_var, compare_base; | |
1221 | enum tree_code compare_code; | |
b3269f54 | 1222 | tree compare_step_var; |
fd757b76 | 1223 | edge then_edge; |
1224 | edge_iterator ei; | |
1225 | ||
1226 | if (predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED) | |
1227 | || predicted_by_p (bb, PRED_LOOP_ITERATIONS) | |
1228 | || predicted_by_p (bb, PRED_LOOP_EXIT)) | |
1229 | return; | |
1230 | ||
1231 | stmt = last_stmt (bb); | |
1232 | if (!stmt || gimple_code (stmt) != GIMPLE_COND) | |
1233 | return; | |
1a91d914 | 1234 | if (!is_comparison_with_loop_invariant_p (as_a <gcond *> (stmt), |
1235 | loop, &compare_var, | |
fd757b76 | 1236 | &compare_code, |
b3269f54 | 1237 | &compare_step_var, |
fd757b76 | 1238 | &compare_base)) |
1239 | return; | |
1240 | ||
1241 | /* Find the taken edge. */ | |
1242 | FOR_EACH_EDGE (then_edge, ei, bb->succs) | |
1243 | if (then_edge->flags & EDGE_TRUE_VALUE) | |
1244 | break; | |
1245 | ||
1246 | /* When comparing an IV to a loop invariant, NE is more likely to be | |
1247 | taken while EQ is more likely to be not-taken. */ | |
1248 | if (compare_code == NE_EXPR) | |
1249 | { | |
1250 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1251 | return; | |
1252 | } | |
1253 | else if (compare_code == EQ_EXPR) | |
1254 | { | |
1255 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1256 | return; | |
1257 | } | |
1258 | ||
1259 | if (!expr_coherent_p (loop_iv_base_var, compare_base)) | |
1260 | return; | |
1261 | ||
1262 | /* If loop bound, base and compare bound are all constants, we can | |
1263 | calculate the probability directly. */ | |
e913b5cd | 1264 | if (tree_fits_shwi_p (loop_bound_var) |
1265 | && tree_fits_shwi_p (compare_var) | |
1266 | && tree_fits_shwi_p (compare_base)) | |
fd757b76 | 1267 | { |
1268 | int probability; | |
e913b5cd | 1269 | bool overflow, overall_overflow = false; |
ab2c1de8 | 1270 | widest_int compare_count, tem; |
b3269f54 | 1271 | |
b3269f54 | 1272 | /* (loop_bound - base) / compare_step */ |
c311b856 | 1273 | tem = wi::sub (wi::to_widest (loop_bound_var), |
1274 | wi::to_widest (compare_base), SIGNED, &overflow); | |
e913b5cd | 1275 | overall_overflow |= overflow; |
c311b856 | 1276 | widest_int loop_count = wi::div_trunc (tem, |
1277 | wi::to_widest (compare_step_var), | |
1278 | SIGNED, &overflow); | |
e913b5cd | 1279 | overall_overflow |= overflow; |
1280 | ||
c311b856 | 1281 | if (!wi::neg_p (wi::to_widest (compare_step_var)) |
fd757b76 | 1282 | ^ (compare_code == LT_EXPR || compare_code == LE_EXPR)) |
b3269f54 | 1283 | { |
1284 | /* (loop_bound - compare_bound) / compare_step */ | |
c311b856 | 1285 | tem = wi::sub (wi::to_widest (loop_bound_var), |
1286 | wi::to_widest (compare_var), SIGNED, &overflow); | |
e913b5cd | 1287 | overall_overflow |= overflow; |
c311b856 | 1288 | compare_count = wi::div_trunc (tem, wi::to_widest (compare_step_var), |
1289 | SIGNED, &overflow); | |
e913b5cd | 1290 | overall_overflow |= overflow; |
b3269f54 | 1291 | } |
fd757b76 | 1292 | else |
b3269f54 | 1293 | { |
1294 | /* (compare_bound - base) / compare_step */ | |
c311b856 | 1295 | tem = wi::sub (wi::to_widest (compare_var), |
1296 | wi::to_widest (compare_base), SIGNED, &overflow); | |
e913b5cd | 1297 | overall_overflow |= overflow; |
c311b856 | 1298 | compare_count = wi::div_trunc (tem, wi::to_widest (compare_step_var), |
1299 | SIGNED, &overflow); | |
e913b5cd | 1300 | overall_overflow |= overflow; |
b3269f54 | 1301 | } |
fd757b76 | 1302 | if (compare_code == LE_EXPR || compare_code == GE_EXPR) |
b3269f54 | 1303 | ++compare_count; |
fd757b76 | 1304 | if (loop_bound_code == LE_EXPR || loop_bound_code == GE_EXPR) |
b3269f54 | 1305 | ++loop_count; |
796b6678 | 1306 | if (wi::neg_p (compare_count)) |
e913b5cd | 1307 | compare_count = 0; |
796b6678 | 1308 | if (wi::neg_p (loop_count)) |
e913b5cd | 1309 | loop_count = 0; |
796b6678 | 1310 | if (loop_count == 0) |
fd757b76 | 1311 | probability = 0; |
796b6678 | 1312 | else if (wi::cmps (compare_count, loop_count) == 1) |
fd757b76 | 1313 | probability = REG_BR_PROB_BASE; |
1314 | else | |
b3269f54 | 1315 | { |
e913b5cd | 1316 | tem = compare_count * REG_BR_PROB_BASE; |
796b6678 | 1317 | tem = wi::udiv_trunc (tem, loop_count); |
b3269f54 | 1318 | probability = tem.to_uhwi (); |
1319 | } | |
1320 | ||
e913b5cd | 1321 | if (!overall_overflow) |
b3269f54 | 1322 | predict_edge (then_edge, PRED_LOOP_IV_COMPARE, probability); |
1323 | ||
fd757b76 | 1324 | return; |
1325 | } | |
1326 | ||
1327 | if (expr_coherent_p (loop_bound_var, compare_var)) | |
1328 | { | |
1329 | if ((loop_bound_code == LT_EXPR || loop_bound_code == LE_EXPR) | |
1330 | && (compare_code == LT_EXPR || compare_code == LE_EXPR)) | |
1331 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1332 | else if ((loop_bound_code == GT_EXPR || loop_bound_code == GE_EXPR) | |
1333 | && (compare_code == GT_EXPR || compare_code == GE_EXPR)) | |
1334 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1335 | else if (loop_bound_code == NE_EXPR) | |
1336 | { | |
1337 | /* If the loop backedge condition is "(i != bound)", we do | |
1338 | the comparison based on the step of IV: | |
1339 | * step < 0 : backedge condition is like (i > bound) | |
1340 | * step > 0 : backedge condition is like (i < bound) */ | |
1341 | gcc_assert (loop_bound_step != 0); | |
1342 | if (loop_bound_step > 0 | |
1343 | && (compare_code == LT_EXPR | |
1344 | || compare_code == LE_EXPR)) | |
1345 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1346 | else if (loop_bound_step < 0 | |
1347 | && (compare_code == GT_EXPR | |
1348 | || compare_code == GE_EXPR)) | |
1349 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1350 | else | |
1351 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1352 | } | |
1353 | else | |
1354 | /* The branch is predicted not-taken if loop_bound_code is | |
1355 | opposite with compare_code. */ | |
1356 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1357 | } | |
1358 | else if (expr_coherent_p (loop_iv_base_var, compare_var)) | |
1359 | { | |
1360 | /* For cases like: | |
1361 | for (i = s; i < h; i++) | |
1362 | if (i > s + 2) .... | |
1363 | The branch should be predicted taken. */ | |
1364 | if (loop_bound_step > 0 | |
1365 | && (compare_code == GT_EXPR || compare_code == GE_EXPR)) | |
1366 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1367 | else if (loop_bound_step < 0 | |
1368 | && (compare_code == LT_EXPR || compare_code == LE_EXPR)) | |
1369 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1370 | else | |
1371 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1372 | } | |
1373 | } | |
4ca17abf | 1374 | |
1375 | /* Predict for extra loop exits that will lead to EXIT_EDGE. The extra loop | |
1376 | exits are resulted from short-circuit conditions that will generate an | |
1377 | if_tmp. E.g.: | |
1378 | ||
1379 | if (foo() || global > 10) | |
1380 | break; | |
1381 | ||
1382 | This will be translated into: | |
1383 | ||
1384 | BB3: | |
1385 | loop header... | |
1386 | BB4: | |
1387 | if foo() goto BB6 else goto BB5 | |
1388 | BB5: | |
1389 | if global > 10 goto BB6 else goto BB7 | |
1390 | BB6: | |
1391 | goto BB7 | |
1392 | BB7: | |
1393 | iftmp = (PHI 0(BB5), 1(BB6)) | |
1394 | if iftmp == 1 goto BB8 else goto BB3 | |
1395 | BB8: | |
1396 | outside of the loop... | |
1397 | ||
1398 | The edge BB7->BB8 is loop exit because BB8 is outside of the loop. | |
1399 | From the dataflow, we can infer that BB4->BB6 and BB5->BB6 are also loop | |
1400 | exits. This function takes BB7->BB8 as input, and finds out the extra loop | |
1401 | exits to predict them using PRED_LOOP_EXIT. */ | |
1402 | ||
1403 | static void | |
1404 | predict_extra_loop_exits (edge exit_edge) | |
1405 | { | |
1406 | unsigned i; | |
1407 | bool check_value_one; | |
1a91d914 | 1408 | gimple lhs_def_stmt; |
1409 | gphi *phi_stmt; | |
4ca17abf | 1410 | tree cmp_rhs, cmp_lhs; |
1a91d914 | 1411 | gimple last; |
1412 | gcond *cmp_stmt; | |
4ca17abf | 1413 | |
1a91d914 | 1414 | last = last_stmt (exit_edge->src); |
1415 | if (!last) | |
1416 | return; | |
1417 | cmp_stmt = dyn_cast <gcond *> (last); | |
1418 | if (!cmp_stmt) | |
4ca17abf | 1419 | return; |
1a91d914 | 1420 | |
4ca17abf | 1421 | cmp_rhs = gimple_cond_rhs (cmp_stmt); |
1422 | cmp_lhs = gimple_cond_lhs (cmp_stmt); | |
1423 | if (!TREE_CONSTANT (cmp_rhs) | |
1424 | || !(integer_zerop (cmp_rhs) || integer_onep (cmp_rhs))) | |
1425 | return; | |
1426 | if (TREE_CODE (cmp_lhs) != SSA_NAME) | |
1427 | return; | |
1428 | ||
1429 | /* If check_value_one is true, only the phi_args with value '1' will lead | |
1430 | to loop exit. Otherwise, only the phi_args with value '0' will lead to | |
1431 | loop exit. */ | |
1432 | check_value_one = (((integer_onep (cmp_rhs)) | |
1433 | ^ (gimple_cond_code (cmp_stmt) == EQ_EXPR)) | |
1434 | ^ ((exit_edge->flags & EDGE_TRUE_VALUE) != 0)); | |
1435 | ||
1a91d914 | 1436 | lhs_def_stmt = SSA_NAME_DEF_STMT (cmp_lhs); |
1437 | if (!lhs_def_stmt) | |
1438 | return; | |
1439 | ||
1440 | phi_stmt = dyn_cast <gphi *> (lhs_def_stmt); | |
1441 | if (!phi_stmt) | |
4ca17abf | 1442 | return; |
1443 | ||
1444 | for (i = 0; i < gimple_phi_num_args (phi_stmt); i++) | |
1445 | { | |
1446 | edge e1; | |
1447 | edge_iterator ei; | |
1448 | tree val = gimple_phi_arg_def (phi_stmt, i); | |
1449 | edge e = gimple_phi_arg_edge (phi_stmt, i); | |
1450 | ||
1451 | if (!TREE_CONSTANT (val) || !(integer_zerop (val) || integer_onep (val))) | |
1452 | continue; | |
1453 | if ((check_value_one ^ integer_onep (val)) == 1) | |
1454 | continue; | |
1455 | if (EDGE_COUNT (e->src->succs) != 1) | |
1456 | { | |
1457 | predict_paths_leading_to_edge (e, PRED_LOOP_EXIT, NOT_TAKEN); | |
1458 | continue; | |
1459 | } | |
1460 | ||
1461 | FOR_EACH_EDGE (e1, ei, e->src->preds) | |
1462 | predict_paths_leading_to_edge (e1, PRED_LOOP_EXIT, NOT_TAKEN); | |
1463 | } | |
1464 | } | |
1465 | ||
7194de72 | 1466 | /* Predict edge probabilities by exploiting loop structure. */ |
1467 | ||
4ee9c684 | 1468 | static void |
7194de72 | 1469 | predict_loops (void) |
4ee9c684 | 1470 | { |
17519ba0 | 1471 | struct loop *loop; |
c12f2fcb | 1472 | |
7fcadf62 | 1473 | /* Try to predict out blocks in a loop that are not part of a |
1474 | natural loop. */ | |
f21d4d00 | 1475 | FOR_EACH_LOOP (loop, 0) |
59423b59 | 1476 | { |
7fb12188 | 1477 | basic_block bb, *bbs; |
749ea85f | 1478 | unsigned j, n_exits; |
f1f41a6c | 1479 | vec<edge> exits; |
3b0b2309 | 1480 | struct tree_niter_desc niter_desc; |
749ea85f | 1481 | edge ex; |
fd757b76 | 1482 | struct nb_iter_bound *nb_iter; |
1483 | enum tree_code loop_bound_code = ERROR_MARK; | |
b3269f54 | 1484 | tree loop_bound_step = NULL; |
fd757b76 | 1485 | tree loop_bound_var = NULL; |
1486 | tree loop_iv_base = NULL; | |
1a91d914 | 1487 | gcond *stmt = NULL; |
59423b59 | 1488 | |
749ea85f | 1489 | exits = get_loop_exit_edges (loop); |
f1f41a6c | 1490 | n_exits = exits.length (); |
5d865361 | 1491 | if (!n_exits) |
1492 | { | |
f1f41a6c | 1493 | exits.release (); |
5d865361 | 1494 | continue; |
1495 | } | |
ba38e12b | 1496 | |
f1f41a6c | 1497 | FOR_EACH_VEC_ELT (exits, j, ex) |
d27b0b64 | 1498 | { |
3b0b2309 | 1499 | tree niter = NULL; |
d500fef3 | 1500 | HOST_WIDE_INT nitercst; |
1501 | int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS); | |
1502 | int probability; | |
1503 | enum br_predictor predictor; | |
d27b0b64 | 1504 | |
4ca17abf | 1505 | predict_extra_loop_exits (ex); |
1506 | ||
3f78e715 | 1507 | if (number_of_iterations_exit (loop, ex, &niter_desc, false, false)) |
3b0b2309 | 1508 | niter = niter_desc.niter; |
1509 | if (!niter || TREE_CODE (niter_desc.niter) != INTEGER_CST) | |
749ea85f | 1510 | niter = loop_niter_by_eval (loop, ex); |
d27b0b64 | 1511 | |
3b0b2309 | 1512 | if (TREE_CODE (niter) == INTEGER_CST) |
1513 | { | |
e913b5cd | 1514 | if (tree_fits_uhwi_p (niter) |
ed60f27f | 1515 | && max |
1516 | && compare_tree_int (niter, max - 1) == -1) | |
e913b5cd | 1517 | nitercst = tree_to_uhwi (niter) + 1; |
3b0b2309 | 1518 | else |
d500fef3 | 1519 | nitercst = max; |
1520 | predictor = PRED_LOOP_ITERATIONS; | |
1521 | } | |
1522 | /* If we have just one exit and we can derive some information about | |
1523 | the number of iterations of the loop from the statements inside | |
1524 | the loop, use it to predict this exit. */ | |
1525 | else if (n_exits == 1) | |
1526 | { | |
fee017b3 | 1527 | nitercst = estimated_stmt_executions_int (loop); |
d500fef3 | 1528 | if (nitercst < 0) |
1529 | continue; | |
1530 | if (nitercst > max) | |
1531 | nitercst = max; | |
d27b0b64 | 1532 | |
d500fef3 | 1533 | predictor = PRED_LOOP_ITERATIONS_GUESSED; |
3b0b2309 | 1534 | } |
d500fef3 | 1535 | else |
1536 | continue; | |
1537 | ||
ed60f27f | 1538 | /* If the prediction for number of iterations is zero, do not |
1539 | predict the exit edges. */ | |
1540 | if (nitercst == 0) | |
1541 | continue; | |
1542 | ||
d500fef3 | 1543 | probability = ((REG_BR_PROB_BASE + nitercst / 2) / nitercst); |
1544 | predict_edge (ex, predictor, probability); | |
d27b0b64 | 1545 | } |
f1f41a6c | 1546 | exits.release (); |
862be747 | 1547 | |
fd757b76 | 1548 | /* Find information about loop bound variables. */ |
1549 | for (nb_iter = loop->bounds; nb_iter; | |
1550 | nb_iter = nb_iter->next) | |
1551 | if (nb_iter->stmt | |
1552 | && gimple_code (nb_iter->stmt) == GIMPLE_COND) | |
1553 | { | |
1a91d914 | 1554 | stmt = as_a <gcond *> (nb_iter->stmt); |
fd757b76 | 1555 | break; |
1556 | } | |
1557 | if (!stmt && last_stmt (loop->header) | |
1558 | && gimple_code (last_stmt (loop->header)) == GIMPLE_COND) | |
1a91d914 | 1559 | stmt = as_a <gcond *> (last_stmt (loop->header)); |
fd757b76 | 1560 | if (stmt) |
1561 | is_comparison_with_loop_invariant_p (stmt, loop, | |
1562 | &loop_bound_var, | |
1563 | &loop_bound_code, | |
1564 | &loop_bound_step, | |
1565 | &loop_iv_base); | |
1566 | ||
7fb12188 | 1567 | bbs = get_loop_body (loop); |
4ee9c684 | 1568 | |
7fb12188 | 1569 | for (j = 0; j < loop->num_nodes; j++) |
1570 | { | |
1571 | int header_found = 0; | |
1572 | edge e; | |
cd665a06 | 1573 | edge_iterator ei; |
7fb12188 | 1574 | |
1575 | bb = bbs[j]; | |
e6751e9a | 1576 | |
cd0fe062 | 1577 | /* Bypass loop heuristics on continue statement. These |
1578 | statements construct loops via "non-loop" constructs | |
1579 | in the source language and are better to be handled | |
1580 | separately. */ | |
3b0b2309 | 1581 | if (predicted_by_p (bb, PRED_CONTINUE)) |
cd0fe062 | 1582 | continue; |
1583 | ||
7fb12188 | 1584 | /* Loop branch heuristics - predict an edge back to a |
1585 | loop's head as taken. */ | |
c6356c17 | 1586 | if (bb == loop->latch) |
1587 | { | |
1588 | e = find_edge (loop->latch, loop->header); | |
1589 | if (e) | |
1590 | { | |
1591 | header_found = 1; | |
1592 | predict_edge_def (e, PRED_LOOP_BRANCH, TAKEN); | |
1593 | } | |
1594 | } | |
e6751e9a | 1595 | |
7fb12188 | 1596 | /* Loop exit heuristics - predict an edge exiting the loop if the |
41a6f238 | 1597 | conditional has no loop header successors as not taken. */ |
d500fef3 | 1598 | if (!header_found |
1599 | /* If we already used more reliable loop exit predictors, do not | |
1600 | bother with PRED_LOOP_EXIT. */ | |
1601 | && !predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED) | |
1602 | && !predicted_by_p (bb, PRED_LOOP_ITERATIONS)) | |
b41438e5 | 1603 | { |
1604 | /* For loop with many exits we don't want to predict all exits | |
1605 | with the pretty large probability, because if all exits are | |
1606 | considered in row, the loop would be predicted to iterate | |
1607 | almost never. The code to divide probability by number of | |
1608 | exits is very rough. It should compute the number of exits | |
1609 | taken in each patch through function (not the overall number | |
1610 | of exits that might be a lot higher for loops with wide switch | |
1611 | statements in them) and compute n-th square root. | |
1612 | ||
1613 | We limit the minimal probability by 2% to avoid | |
1614 | EDGE_PROBABILITY_RELIABLE from trusting the branch prediction | |
1615 | as this was causing regression in perl benchmark containing such | |
1616 | a wide loop. */ | |
48e1416a | 1617 | |
b41438e5 | 1618 | int probability = ((REG_BR_PROB_BASE |
1619 | - predictor_info [(int) PRED_LOOP_EXIT].hitrate) | |
1620 | / n_exits); | |
1621 | if (probability < HITRATE (2)) | |
1622 | probability = HITRATE (2); | |
1623 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1624 | if (e->dest->index < NUM_FIXED_BLOCKS | |
1625 | || !flow_bb_inside_loop_p (loop, e->dest)) | |
1626 | predict_edge (e, PRED_LOOP_EXIT, probability); | |
1627 | } | |
fd757b76 | 1628 | if (loop_bound_var) |
1629 | predict_iv_comparison (loop, bb, loop_bound_var, loop_iv_base, | |
1630 | loop_bound_code, | |
e913b5cd | 1631 | tree_to_shwi (loop_bound_step)); |
7fb12188 | 1632 | } |
48e1416a | 1633 | |
21dda4ee | 1634 | /* Free basic blocks from get_loop_body. */ |
dcd8fd01 | 1635 | free (bbs); |
59423b59 | 1636 | } |
4ee9c684 | 1637 | } |
1638 | ||
83c8a977 | 1639 | /* Attempt to predict probabilities of BB outgoing edges using local |
1640 | properties. */ | |
1641 | static void | |
1642 | bb_estimate_probability_locally (basic_block bb) | |
1643 | { | |
ee5f6585 | 1644 | rtx_insn *last_insn = BB_END (bb); |
83c8a977 | 1645 | rtx cond; |
1646 | ||
1647 | if (! can_predict_insn_p (last_insn)) | |
1648 | return; | |
1649 | cond = get_condition (last_insn, NULL, false, false); | |
1650 | if (! cond) | |
1651 | return; | |
1652 | ||
1653 | /* Try "pointer heuristic." | |
1654 | A comparison ptr == 0 is predicted as false. | |
1655 | Similarly, a comparison ptr1 == ptr2 is predicted as false. */ | |
1656 | if (COMPARISON_P (cond) | |
1657 | && ((REG_P (XEXP (cond, 0)) && REG_POINTER (XEXP (cond, 0))) | |
1658 | || (REG_P (XEXP (cond, 1)) && REG_POINTER (XEXP (cond, 1))))) | |
1659 | { | |
1660 | if (GET_CODE (cond) == EQ) | |
1661 | predict_insn_def (last_insn, PRED_POINTER, NOT_TAKEN); | |
1662 | else if (GET_CODE (cond) == NE) | |
1663 | predict_insn_def (last_insn, PRED_POINTER, TAKEN); | |
1664 | } | |
1665 | else | |
1666 | ||
1667 | /* Try "opcode heuristic." | |
1668 | EQ tests are usually false and NE tests are usually true. Also, | |
1669 | most quantities are positive, so we can make the appropriate guesses | |
1670 | about signed comparisons against zero. */ | |
1671 | switch (GET_CODE (cond)) | |
1672 | { | |
1673 | case CONST_INT: | |
1674 | /* Unconditional branch. */ | |
1675 | predict_insn_def (last_insn, PRED_UNCONDITIONAL, | |
1676 | cond == const0_rtx ? NOT_TAKEN : TAKEN); | |
1677 | break; | |
1678 | ||
1679 | case EQ: | |
1680 | case UNEQ: | |
1681 | /* Floating point comparisons appears to behave in a very | |
1682 | unpredictable way because of special role of = tests in | |
1683 | FP code. */ | |
1684 | if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0)))) | |
1685 | ; | |
1686 | /* Comparisons with 0 are often used for booleans and there is | |
1687 | nothing useful to predict about them. */ | |
1688 | else if (XEXP (cond, 1) == const0_rtx | |
1689 | || XEXP (cond, 0) == const0_rtx) | |
1690 | ; | |
1691 | else | |
1692 | predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, NOT_TAKEN); | |
1693 | break; | |
1694 | ||
1695 | case NE: | |
1696 | case LTGT: | |
1697 | /* Floating point comparisons appears to behave in a very | |
1698 | unpredictable way because of special role of = tests in | |
1699 | FP code. */ | |
1700 | if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0)))) | |
1701 | ; | |
1702 | /* Comparisons with 0 are often used for booleans and there is | |
1703 | nothing useful to predict about them. */ | |
1704 | else if (XEXP (cond, 1) == const0_rtx | |
1705 | || XEXP (cond, 0) == const0_rtx) | |
1706 | ; | |
1707 | else | |
1708 | predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, TAKEN); | |
1709 | break; | |
1710 | ||
1711 | case ORDERED: | |
1712 | predict_insn_def (last_insn, PRED_FPOPCODE, TAKEN); | |
1713 | break; | |
1714 | ||
1715 | case UNORDERED: | |
1716 | predict_insn_def (last_insn, PRED_FPOPCODE, NOT_TAKEN); | |
1717 | break; | |
1718 | ||
1719 | case LE: | |
1720 | case LT: | |
1721 | if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx | |
1722 | || XEXP (cond, 1) == constm1_rtx) | |
1723 | predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, NOT_TAKEN); | |
1724 | break; | |
1725 | ||
1726 | case GE: | |
1727 | case GT: | |
1728 | if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx | |
1729 | || XEXP (cond, 1) == constm1_rtx) | |
1730 | predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, TAKEN); | |
1731 | break; | |
1732 | ||
1733 | default: | |
1734 | break; | |
1735 | } | |
1736 | } | |
1737 | ||
7edd21a5 | 1738 | /* Set edge->probability for each successor edge of BB. */ |
83c8a977 | 1739 | void |
1740 | guess_outgoing_edge_probabilities (basic_block bb) | |
1741 | { | |
1742 | bb_estimate_probability_locally (bb); | |
1743 | combine_predictions_for_insn (BB_END (bb), bb); | |
1744 | } | |
4ee9c684 | 1745 | \f |
c83059be | 1746 | static tree expr_expected_value (tree, bitmap, enum br_predictor *predictor); |
75a70cf9 | 1747 | |
1748 | /* Helper function for expr_expected_value. */ | |
42975b1f | 1749 | |
1750 | static tree | |
2380e91e | 1751 | expr_expected_value_1 (tree type, tree op0, enum tree_code code, |
c83059be | 1752 | tree op1, bitmap visited, enum br_predictor *predictor) |
42975b1f | 1753 | { |
75a70cf9 | 1754 | gimple def; |
1755 | ||
c83059be | 1756 | if (predictor) |
1757 | *predictor = PRED_UNCONDITIONAL; | |
1758 | ||
75a70cf9 | 1759 | if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS) |
42975b1f | 1760 | { |
75a70cf9 | 1761 | if (TREE_CONSTANT (op0)) |
1762 | return op0; | |
1763 | ||
1764 | if (code != SSA_NAME) | |
1765 | return NULL_TREE; | |
1766 | ||
1767 | def = SSA_NAME_DEF_STMT (op0); | |
42975b1f | 1768 | |
1769 | /* If we were already here, break the infinite cycle. */ | |
6ef9bbe0 | 1770 | if (!bitmap_set_bit (visited, SSA_NAME_VERSION (op0))) |
42975b1f | 1771 | return NULL; |
42975b1f | 1772 | |
75a70cf9 | 1773 | if (gimple_code (def) == GIMPLE_PHI) |
42975b1f | 1774 | { |
1775 | /* All the arguments of the PHI node must have the same constant | |
1776 | length. */ | |
75a70cf9 | 1777 | int i, n = gimple_phi_num_args (def); |
42975b1f | 1778 | tree val = NULL, new_val; |
4ee9c684 | 1779 | |
75a70cf9 | 1780 | for (i = 0; i < n; i++) |
42975b1f | 1781 | { |
1782 | tree arg = PHI_ARG_DEF (def, i); | |
c83059be | 1783 | enum br_predictor predictor2; |
42975b1f | 1784 | |
1785 | /* If this PHI has itself as an argument, we cannot | |
1786 | determine the string length of this argument. However, | |
86481e89 | 1787 | if we can find an expected constant value for the other |
42975b1f | 1788 | PHI args then we can still be sure that this is |
1789 | likely a constant. So be optimistic and just | |
1790 | continue with the next argument. */ | |
1791 | if (arg == PHI_RESULT (def)) | |
1792 | continue; | |
1793 | ||
c83059be | 1794 | new_val = expr_expected_value (arg, visited, &predictor2); |
1795 | ||
1796 | /* It is difficult to combine value predictors. Simply assume | |
1797 | that later predictor is weaker and take its prediction. */ | |
1798 | if (predictor && *predictor < predictor2) | |
1799 | *predictor = predictor2; | |
42975b1f | 1800 | if (!new_val) |
1801 | return NULL; | |
1802 | if (!val) | |
1803 | val = new_val; | |
1804 | else if (!operand_equal_p (val, new_val, false)) | |
1805 | return NULL; | |
1806 | } | |
1807 | return val; | |
1808 | } | |
75a70cf9 | 1809 | if (is_gimple_assign (def)) |
42975b1f | 1810 | { |
75a70cf9 | 1811 | if (gimple_assign_lhs (def) != op0) |
1812 | return NULL; | |
42975b1f | 1813 | |
75a70cf9 | 1814 | return expr_expected_value_1 (TREE_TYPE (gimple_assign_lhs (def)), |
1815 | gimple_assign_rhs1 (def), | |
1816 | gimple_assign_rhs_code (def), | |
1817 | gimple_assign_rhs2 (def), | |
c83059be | 1818 | visited, predictor); |
75a70cf9 | 1819 | } |
1820 | ||
1821 | if (is_gimple_call (def)) | |
1822 | { | |
1823 | tree decl = gimple_call_fndecl (def); | |
1824 | if (!decl) | |
c83059be | 1825 | { |
1826 | if (gimple_call_internal_p (def) | |
1827 | && gimple_call_internal_fn (def) == IFN_BUILTIN_EXPECT) | |
1828 | { | |
1829 | gcc_assert (gimple_call_num_args (def) == 3); | |
1830 | tree val = gimple_call_arg (def, 0); | |
1831 | if (TREE_CONSTANT (val)) | |
1832 | return val; | |
1833 | if (predictor) | |
1834 | { | |
c83059be | 1835 | tree val2 = gimple_call_arg (def, 2); |
1836 | gcc_assert (TREE_CODE (val2) == INTEGER_CST | |
1837 | && tree_fits_uhwi_p (val2) | |
1838 | && tree_to_uhwi (val2) < END_PREDICTORS); | |
1839 | *predictor = (enum br_predictor) tree_to_uhwi (val2); | |
1840 | } | |
1841 | return gimple_call_arg (def, 1); | |
1842 | } | |
1843 | return NULL; | |
1844 | } | |
2380e91e | 1845 | if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL) |
1846 | switch (DECL_FUNCTION_CODE (decl)) | |
1847 | { | |
1848 | case BUILT_IN_EXPECT: | |
1849 | { | |
1850 | tree val; | |
1851 | if (gimple_call_num_args (def) != 2) | |
1852 | return NULL; | |
1853 | val = gimple_call_arg (def, 0); | |
1854 | if (TREE_CONSTANT (val)) | |
1855 | return val; | |
c83059be | 1856 | if (predictor) |
1857 | *predictor = PRED_BUILTIN_EXPECT; | |
2380e91e | 1858 | return gimple_call_arg (def, 1); |
1859 | } | |
75a70cf9 | 1860 | |
2380e91e | 1861 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_N: |
1862 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_1: | |
1863 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2: | |
1864 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4: | |
1865 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8: | |
1866 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16: | |
1867 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE: | |
1868 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_N: | |
1869 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1: | |
1870 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2: | |
1871 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4: | |
1872 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8: | |
1873 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16: | |
1874 | /* Assume that any given atomic operation has low contention, | |
1875 | and thus the compare-and-swap operation succeeds. */ | |
c83059be | 1876 | if (predictor) |
1877 | *predictor = PRED_COMPARE_AND_SWAP; | |
2380e91e | 1878 | return boolean_true_node; |
5213d6c9 | 1879 | default: |
1880 | break; | |
75a70cf9 | 1881 | } |
42975b1f | 1882 | } |
75a70cf9 | 1883 | |
1884 | return NULL; | |
42975b1f | 1885 | } |
75a70cf9 | 1886 | |
1887 | if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS) | |
42975b1f | 1888 | { |
75a70cf9 | 1889 | tree res; |
c83059be | 1890 | enum br_predictor predictor2; |
1891 | op0 = expr_expected_value (op0, visited, predictor); | |
42975b1f | 1892 | if (!op0) |
1893 | return NULL; | |
c83059be | 1894 | op1 = expr_expected_value (op1, visited, &predictor2); |
1895 | if (predictor && *predictor < predictor2) | |
1896 | *predictor = predictor2; | |
42975b1f | 1897 | if (!op1) |
1898 | return NULL; | |
75a70cf9 | 1899 | res = fold_build2 (code, type, op0, op1); |
42975b1f | 1900 | if (TREE_CONSTANT (res)) |
1901 | return res; | |
1902 | return NULL; | |
1903 | } | |
75a70cf9 | 1904 | if (get_gimple_rhs_class (code) == GIMPLE_UNARY_RHS) |
42975b1f | 1905 | { |
75a70cf9 | 1906 | tree res; |
c83059be | 1907 | op0 = expr_expected_value (op0, visited, predictor); |
42975b1f | 1908 | if (!op0) |
1909 | return NULL; | |
75a70cf9 | 1910 | res = fold_build1 (code, type, op0); |
42975b1f | 1911 | if (TREE_CONSTANT (res)) |
1912 | return res; | |
1913 | return NULL; | |
1914 | } | |
1915 | return NULL; | |
1916 | } | |
75a70cf9 | 1917 | |
48e1416a | 1918 | /* Return constant EXPR will likely have at execution time, NULL if unknown. |
75a70cf9 | 1919 | The function is used by builtin_expect branch predictor so the evidence |
1920 | must come from this construct and additional possible constant folding. | |
48e1416a | 1921 | |
75a70cf9 | 1922 | We may want to implement more involved value guess (such as value range |
1923 | propagation based prediction), but such tricks shall go to new | |
1924 | implementation. */ | |
1925 | ||
1926 | static tree | |
c83059be | 1927 | expr_expected_value (tree expr, bitmap visited, |
1928 | enum br_predictor *predictor) | |
75a70cf9 | 1929 | { |
1930 | enum tree_code code; | |
1931 | tree op0, op1; | |
1932 | ||
1933 | if (TREE_CONSTANT (expr)) | |
c83059be | 1934 | { |
1935 | if (predictor) | |
1936 | *predictor = PRED_UNCONDITIONAL; | |
1937 | return expr; | |
1938 | } | |
75a70cf9 | 1939 | |
1940 | extract_ops_from_tree (expr, &code, &op0, &op1); | |
1941 | return expr_expected_value_1 (TREE_TYPE (expr), | |
c83059be | 1942 | op0, code, op1, visited, predictor); |
75a70cf9 | 1943 | } |
42975b1f | 1944 | \f |
4ee9c684 | 1945 | /* Predict using opcode of the last statement in basic block. */ |
1946 | static void | |
1947 | tree_predict_by_opcode (basic_block bb) | |
1948 | { | |
75a70cf9 | 1949 | gimple stmt = last_stmt (bb); |
4ee9c684 | 1950 | edge then_edge; |
75a70cf9 | 1951 | tree op0, op1; |
4ee9c684 | 1952 | tree type; |
42975b1f | 1953 | tree val; |
75a70cf9 | 1954 | enum tree_code cmp; |
42975b1f | 1955 | bitmap visited; |
cd665a06 | 1956 | edge_iterator ei; |
c83059be | 1957 | enum br_predictor predictor; |
4ee9c684 | 1958 | |
75a70cf9 | 1959 | if (!stmt || gimple_code (stmt) != GIMPLE_COND) |
4ee9c684 | 1960 | return; |
cd665a06 | 1961 | FOR_EACH_EDGE (then_edge, ei, bb->succs) |
4ee9c684 | 1962 | if (then_edge->flags & EDGE_TRUE_VALUE) |
cd665a06 | 1963 | break; |
75a70cf9 | 1964 | op0 = gimple_cond_lhs (stmt); |
1965 | op1 = gimple_cond_rhs (stmt); | |
1966 | cmp = gimple_cond_code (stmt); | |
4ee9c684 | 1967 | type = TREE_TYPE (op0); |
27335ffd | 1968 | visited = BITMAP_ALLOC (NULL); |
c83059be | 1969 | val = expr_expected_value_1 (boolean_type_node, op0, cmp, op1, visited, |
1970 | &predictor); | |
27335ffd | 1971 | BITMAP_FREE (visited); |
c83059be | 1972 | if (val && TREE_CODE (val) == INTEGER_CST) |
42975b1f | 1973 | { |
c83059be | 1974 | if (predictor == PRED_BUILTIN_EXPECT) |
1975 | { | |
1976 | int percent = PARAM_VALUE (BUILTIN_EXPECT_PROBABILITY); | |
21853731 | 1977 | |
c83059be | 1978 | gcc_assert (percent >= 0 && percent <= 100); |
1979 | if (integer_zerop (val)) | |
1980 | percent = 100 - percent; | |
1981 | predict_edge (then_edge, PRED_BUILTIN_EXPECT, HITRATE (percent)); | |
1982 | } | |
1983 | else | |
1984 | predict_edge (then_edge, predictor, | |
1985 | integer_zerop (val) ? NOT_TAKEN : TAKEN); | |
42975b1f | 1986 | } |
4ee9c684 | 1987 | /* Try "pointer heuristic." |
1988 | A comparison ptr == 0 is predicted as false. | |
1989 | Similarly, a comparison ptr1 == ptr2 is predicted as false. */ | |
1990 | if (POINTER_TYPE_P (type)) | |
1991 | { | |
75a70cf9 | 1992 | if (cmp == EQ_EXPR) |
4ee9c684 | 1993 | predict_edge_def (then_edge, PRED_TREE_POINTER, NOT_TAKEN); |
75a70cf9 | 1994 | else if (cmp == NE_EXPR) |
4ee9c684 | 1995 | predict_edge_def (then_edge, PRED_TREE_POINTER, TAKEN); |
1996 | } | |
1997 | else | |
1998 | ||
1999 | /* Try "opcode heuristic." | |
2000 | EQ tests are usually false and NE tests are usually true. Also, | |
2001 | most quantities are positive, so we can make the appropriate guesses | |
2002 | about signed comparisons against zero. */ | |
75a70cf9 | 2003 | switch (cmp) |
4ee9c684 | 2004 | { |
2005 | case EQ_EXPR: | |
2006 | case UNEQ_EXPR: | |
2007 | /* Floating point comparisons appears to behave in a very | |
2008 | unpredictable way because of special role of = tests in | |
2009 | FP code. */ | |
2010 | if (FLOAT_TYPE_P (type)) | |
2011 | ; | |
2012 | /* Comparisons with 0 are often used for booleans and there is | |
2013 | nothing useful to predict about them. */ | |
75a70cf9 | 2014 | else if (integer_zerop (op0) || integer_zerop (op1)) |
4ee9c684 | 2015 | ; |
2016 | else | |
2017 | predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, NOT_TAKEN); | |
2018 | break; | |
2019 | ||
2020 | case NE_EXPR: | |
318a728f | 2021 | case LTGT_EXPR: |
4ee9c684 | 2022 | /* Floating point comparisons appears to behave in a very |
2023 | unpredictable way because of special role of = tests in | |
2024 | FP code. */ | |
2025 | if (FLOAT_TYPE_P (type)) | |
2026 | ; | |
2027 | /* Comparisons with 0 are often used for booleans and there is | |
2028 | nothing useful to predict about them. */ | |
2029 | else if (integer_zerop (op0) | |
75a70cf9 | 2030 | || integer_zerop (op1)) |
4ee9c684 | 2031 | ; |
2032 | else | |
2033 | predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, TAKEN); | |
2034 | break; | |
2035 | ||
2036 | case ORDERED_EXPR: | |
2037 | predict_edge_def (then_edge, PRED_TREE_FPOPCODE, TAKEN); | |
2038 | break; | |
2039 | ||
2040 | case UNORDERED_EXPR: | |
2041 | predict_edge_def (then_edge, PRED_TREE_FPOPCODE, NOT_TAKEN); | |
2042 | break; | |
2043 | ||
2044 | case LE_EXPR: | |
2045 | case LT_EXPR: | |
75a70cf9 | 2046 | if (integer_zerop (op1) |
2047 | || integer_onep (op1) | |
2048 | || integer_all_onesp (op1) | |
2049 | || real_zerop (op1) | |
2050 | || real_onep (op1) | |
2051 | || real_minus_onep (op1)) | |
4ee9c684 | 2052 | predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, NOT_TAKEN); |
2053 | break; | |
2054 | ||
2055 | case GE_EXPR: | |
2056 | case GT_EXPR: | |
75a70cf9 | 2057 | if (integer_zerop (op1) |
2058 | || integer_onep (op1) | |
2059 | || integer_all_onesp (op1) | |
2060 | || real_zerop (op1) | |
2061 | || real_onep (op1) | |
2062 | || real_minus_onep (op1)) | |
4ee9c684 | 2063 | predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, TAKEN); |
2064 | break; | |
2065 | ||
2066 | default: | |
2067 | break; | |
2068 | } | |
2069 | } | |
2070 | ||
f816ec49 | 2071 | /* Try to guess whether the value of return means error code. */ |
75a70cf9 | 2072 | |
f816ec49 | 2073 | static enum br_predictor |
2074 | return_prediction (tree val, enum prediction *prediction) | |
2075 | { | |
2076 | /* VOID. */ | |
2077 | if (!val) | |
2078 | return PRED_NO_PREDICTION; | |
2079 | /* Different heuristics for pointers and scalars. */ | |
2080 | if (POINTER_TYPE_P (TREE_TYPE (val))) | |
2081 | { | |
2082 | /* NULL is usually not returned. */ | |
2083 | if (integer_zerop (val)) | |
2084 | { | |
2085 | *prediction = NOT_TAKEN; | |
2086 | return PRED_NULL_RETURN; | |
2087 | } | |
2088 | } | |
2089 | else if (INTEGRAL_TYPE_P (TREE_TYPE (val))) | |
2090 | { | |
2091 | /* Negative return values are often used to indicate | |
2092 | errors. */ | |
2093 | if (TREE_CODE (val) == INTEGER_CST | |
2094 | && tree_int_cst_sgn (val) < 0) | |
2095 | { | |
2096 | *prediction = NOT_TAKEN; | |
2097 | return PRED_NEGATIVE_RETURN; | |
2098 | } | |
2099 | /* Constant return values seems to be commonly taken. | |
2100 | Zero/one often represent booleans so exclude them from the | |
2101 | heuristics. */ | |
2102 | if (TREE_CONSTANT (val) | |
2103 | && (!integer_zerop (val) && !integer_onep (val))) | |
2104 | { | |
2105 | *prediction = TAKEN; | |
4a4e4487 | 2106 | return PRED_CONST_RETURN; |
f816ec49 | 2107 | } |
2108 | } | |
2109 | return PRED_NO_PREDICTION; | |
2110 | } | |
2111 | ||
2112 | /* Find the basic block with return expression and look up for possible | |
2113 | return value trying to apply RETURN_PREDICTION heuristics. */ | |
2114 | static void | |
d704ea82 | 2115 | apply_return_prediction (void) |
f816ec49 | 2116 | { |
1a91d914 | 2117 | greturn *return_stmt = NULL; |
f816ec49 | 2118 | tree return_val; |
2119 | edge e; | |
1a91d914 | 2120 | gphi *phi; |
f816ec49 | 2121 | int phi_num_args, i; |
2122 | enum br_predictor pred; | |
2123 | enum prediction direction; | |
cd665a06 | 2124 | edge_iterator ei; |
f816ec49 | 2125 | |
34154e27 | 2126 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) |
f816ec49 | 2127 | { |
1a91d914 | 2128 | gimple last = last_stmt (e->src); |
2129 | if (last | |
2130 | && gimple_code (last) == GIMPLE_RETURN) | |
2131 | { | |
2132 | return_stmt = as_a <greturn *> (last); | |
2133 | break; | |
2134 | } | |
f816ec49 | 2135 | } |
2136 | if (!e) | |
2137 | return; | |
75a70cf9 | 2138 | return_val = gimple_return_retval (return_stmt); |
f816ec49 | 2139 | if (!return_val) |
2140 | return; | |
f816ec49 | 2141 | if (TREE_CODE (return_val) != SSA_NAME |
2142 | || !SSA_NAME_DEF_STMT (return_val) | |
75a70cf9 | 2143 | || gimple_code (SSA_NAME_DEF_STMT (return_val)) != GIMPLE_PHI) |
f816ec49 | 2144 | return; |
1a91d914 | 2145 | phi = as_a <gphi *> (SSA_NAME_DEF_STMT (return_val)); |
75a70cf9 | 2146 | phi_num_args = gimple_phi_num_args (phi); |
f816ec49 | 2147 | pred = return_prediction (PHI_ARG_DEF (phi, 0), &direction); |
2148 | ||
2149 | /* Avoid the degenerate case where all return values form the function | |
2150 | belongs to same category (ie they are all positive constants) | |
2151 | so we can hardly say something about them. */ | |
2152 | for (i = 1; i < phi_num_args; i++) | |
2153 | if (pred != return_prediction (PHI_ARG_DEF (phi, i), &direction)) | |
2154 | break; | |
2155 | if (i != phi_num_args) | |
2156 | for (i = 0; i < phi_num_args; i++) | |
2157 | { | |
2158 | pred = return_prediction (PHI_ARG_DEF (phi, i), &direction); | |
2159 | if (pred != PRED_NO_PREDICTION) | |
5707768a | 2160 | predict_paths_leading_to_edge (gimple_phi_arg_edge (phi, i), pred, |
2161 | direction); | |
f816ec49 | 2162 | } |
2163 | } | |
2164 | ||
2165 | /* Look for basic block that contains unlikely to happen events | |
2166 | (such as noreturn calls) and mark all paths leading to execution | |
2167 | of this basic blocks as unlikely. */ | |
2168 | ||
2169 | static void | |
2170 | tree_bb_level_predictions (void) | |
2171 | { | |
2172 | basic_block bb; | |
9f694a82 | 2173 | bool has_return_edges = false; |
2174 | edge e; | |
2175 | edge_iterator ei; | |
2176 | ||
34154e27 | 2177 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) |
9f694a82 | 2178 | if (!(e->flags & (EDGE_ABNORMAL | EDGE_FAKE | EDGE_EH))) |
2179 | { | |
2180 | has_return_edges = true; | |
2181 | break; | |
2182 | } | |
f816ec49 | 2183 | |
d704ea82 | 2184 | apply_return_prediction (); |
f816ec49 | 2185 | |
fc00614f | 2186 | FOR_EACH_BB_FN (bb, cfun) |
f816ec49 | 2187 | { |
75a70cf9 | 2188 | gimple_stmt_iterator gsi; |
f816ec49 | 2189 | |
1add270f | 2190 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
f816ec49 | 2191 | { |
75a70cf9 | 2192 | gimple stmt = gsi_stmt (gsi); |
5de92639 | 2193 | tree decl; |
3ed4a4a1 | 2194 | |
75a70cf9 | 2195 | if (is_gimple_call (stmt)) |
f816ec49 | 2196 | { |
9f694a82 | 2197 | if ((gimple_call_flags (stmt) & ECF_NORETURN) |
2198 | && has_return_edges) | |
75a70cf9 | 2199 | predict_paths_leading_to (bb, PRED_NORETURN, |
2200 | NOT_TAKEN); | |
2201 | decl = gimple_call_fndecl (stmt); | |
2202 | if (decl | |
2203 | && lookup_attribute ("cold", | |
2204 | DECL_ATTRIBUTES (decl))) | |
2205 | predict_paths_leading_to (bb, PRED_COLD_FUNCTION, | |
2206 | NOT_TAKEN); | |
f816ec49 | 2207 | } |
75a70cf9 | 2208 | else if (gimple_code (stmt) == GIMPLE_PREDICT) |
2209 | { | |
2210 | predict_paths_leading_to (bb, gimple_predict_predictor (stmt), | |
2211 | gimple_predict_outcome (stmt)); | |
1add270f | 2212 | /* Keep GIMPLE_PREDICT around so early inlining will propagate |
2213 | hints to callers. */ | |
75a70cf9 | 2214 | } |
f816ec49 | 2215 | } |
2216 | } | |
f816ec49 | 2217 | } |
2218 | ||
b3723726 | 2219 | #ifdef ENABLE_CHECKING |
2220 | ||
06ecf488 | 2221 | /* Callback for hash_map::traverse, asserts that the pointer map is |
b3723726 | 2222 | empty. */ |
2223 | ||
06ecf488 | 2224 | bool |
2225 | assert_is_empty (const_basic_block const &, edge_prediction *const &value, | |
2226 | void *) | |
b3723726 | 2227 | { |
06ecf488 | 2228 | gcc_assert (!value); |
b3723726 | 2229 | return false; |
2230 | } | |
2231 | #endif | |
2232 | ||
675d86b2 | 2233 | /* Predict branch probabilities and estimate profile for basic block BB. */ |
2234 | ||
2235 | static void | |
2236 | tree_estimate_probability_bb (basic_block bb) | |
2237 | { | |
2238 | edge e; | |
2239 | edge_iterator ei; | |
2240 | gimple last; | |
2241 | ||
2242 | FOR_EACH_EDGE (e, ei, bb->succs) | |
2243 | { | |
758a38ab | 2244 | /* Predict edges to user labels with attributes. */ |
34154e27 | 2245 | if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)) |
758a38ab | 2246 | { |
2247 | gimple_stmt_iterator gi; | |
2248 | for (gi = gsi_start_bb (e->dest); !gsi_end_p (gi); gsi_next (&gi)) | |
2249 | { | |
1a91d914 | 2250 | glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gi)); |
758a38ab | 2251 | tree decl; |
2252 | ||
1a91d914 | 2253 | if (!label_stmt) |
758a38ab | 2254 | break; |
1a91d914 | 2255 | decl = gimple_label_label (label_stmt); |
758a38ab | 2256 | if (DECL_ARTIFICIAL (decl)) |
2257 | continue; | |
2258 | ||
2259 | /* Finally, we have a user-defined label. */ | |
2260 | if (lookup_attribute ("cold", DECL_ATTRIBUTES (decl))) | |
2261 | predict_edge_def (e, PRED_COLD_LABEL, NOT_TAKEN); | |
2262 | else if (lookup_attribute ("hot", DECL_ATTRIBUTES (decl))) | |
2263 | predict_edge_def (e, PRED_HOT_LABEL, TAKEN); | |
2264 | } | |
2265 | } | |
2266 | ||
675d86b2 | 2267 | /* Predict early returns to be probable, as we've already taken |
2268 | care for error returns and other cases are often used for | |
2269 | fast paths through function. | |
2270 | ||
2271 | Since we've already removed the return statements, we are | |
2272 | looking for CFG like: | |
2273 | ||
2274 | if (conditional) | |
2275 | { | |
2276 | .. | |
2277 | goto return_block | |
2278 | } | |
2279 | some other blocks | |
2280 | return_block: | |
2281 | return_stmt. */ | |
2282 | if (e->dest != bb->next_bb | |
34154e27 | 2283 | && e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) |
675d86b2 | 2284 | && single_succ_p (e->dest) |
34154e27 | 2285 | && single_succ_edge (e->dest)->dest == EXIT_BLOCK_PTR_FOR_FN (cfun) |
675d86b2 | 2286 | && (last = last_stmt (e->dest)) != NULL |
2287 | && gimple_code (last) == GIMPLE_RETURN) | |
2288 | { | |
2289 | edge e1; | |
2290 | edge_iterator ei1; | |
2291 | ||
2292 | if (single_succ_p (bb)) | |
2293 | { | |
2294 | FOR_EACH_EDGE (e1, ei1, bb->preds) | |
2295 | if (!predicted_by_p (e1->src, PRED_NULL_RETURN) | |
2296 | && !predicted_by_p (e1->src, PRED_CONST_RETURN) | |
2297 | && !predicted_by_p (e1->src, PRED_NEGATIVE_RETURN)) | |
2298 | predict_edge_def (e1, PRED_TREE_EARLY_RETURN, NOT_TAKEN); | |
2299 | } | |
2300 | else | |
2301 | if (!predicted_by_p (e->src, PRED_NULL_RETURN) | |
2302 | && !predicted_by_p (e->src, PRED_CONST_RETURN) | |
2303 | && !predicted_by_p (e->src, PRED_NEGATIVE_RETURN)) | |
2304 | predict_edge_def (e, PRED_TREE_EARLY_RETURN, NOT_TAKEN); | |
2305 | } | |
2306 | ||
2307 | /* Look for block we are guarding (ie we dominate it, | |
2308 | but it doesn't postdominate us). */ | |
34154e27 | 2309 | if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) && e->dest != bb |
675d86b2 | 2310 | && dominated_by_p (CDI_DOMINATORS, e->dest, e->src) |
2311 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e->dest)) | |
2312 | { | |
2313 | gimple_stmt_iterator bi; | |
2314 | ||
2315 | /* The call heuristic claims that a guarded function call | |
2316 | is improbable. This is because such calls are often used | |
2317 | to signal exceptional situations such as printing error | |
2318 | messages. */ | |
2319 | for (bi = gsi_start_bb (e->dest); !gsi_end_p (bi); | |
2320 | gsi_next (&bi)) | |
2321 | { | |
2322 | gimple stmt = gsi_stmt (bi); | |
2323 | if (is_gimple_call (stmt) | |
2324 | /* Constant and pure calls are hardly used to signalize | |
2325 | something exceptional. */ | |
2326 | && gimple_has_side_effects (stmt)) | |
2327 | { | |
2328 | predict_edge_def (e, PRED_CALL, NOT_TAKEN); | |
2329 | break; | |
2330 | } | |
2331 | } | |
2332 | } | |
2333 | } | |
2334 | tree_predict_by_opcode (bb); | |
2335 | } | |
2336 | ||
2337 | /* Predict branch probabilities and estimate profile of the tree CFG. | |
2338 | This function can be called from the loop optimizers to recompute | |
2339 | the profile information. */ | |
2340 | ||
2341 | void | |
4ee9c684 | 2342 | tree_estimate_probability (void) |
2343 | { | |
2344 | basic_block bb; | |
4ee9c684 | 2345 | |
f816ec49 | 2346 | add_noreturn_fake_exit_edges (); |
4ee9c684 | 2347 | connect_infinite_loops_to_exit (); |
d8a0d6b8 | 2348 | /* We use loop_niter_by_eval, which requires that the loops have |
2349 | preheaders. */ | |
2350 | create_preheaders (CP_SIMPLE_PREHEADERS); | |
4ee9c684 | 2351 | calculate_dominance_info (CDI_POST_DOMINATORS); |
2352 | ||
06ecf488 | 2353 | bb_predictions = new hash_map<const_basic_block, edge_prediction *>; |
f816ec49 | 2354 | tree_bb_level_predictions (); |
d500fef3 | 2355 | record_loop_exits (); |
675d86b2 | 2356 | |
41f75a99 | 2357 | if (number_of_loops (cfun) > 1) |
7194de72 | 2358 | predict_loops (); |
4ee9c684 | 2359 | |
fc00614f | 2360 | FOR_EACH_BB_FN (bb, cfun) |
675d86b2 | 2361 | tree_estimate_probability_bb (bb); |
4ee9c684 | 2362 | |
fc00614f | 2363 | FOR_EACH_BB_FN (bb, cfun) |
3f5be5f4 | 2364 | combine_predictions_for_bb (bb); |
f81d9f78 | 2365 | |
b3723726 | 2366 | #ifdef ENABLE_CHECKING |
06ecf488 | 2367 | bb_predictions->traverse<void *, assert_is_empty> (NULL); |
b3723726 | 2368 | #endif |
06ecf488 | 2369 | delete bb_predictions; |
b3723726 | 2370 | bb_predictions = NULL; |
2371 | ||
5327650f | 2372 | estimate_bb_frequencies (false); |
4ee9c684 | 2373 | free_dominance_info (CDI_POST_DOMINATORS); |
41d24834 | 2374 | remove_fake_exit_edges (); |
675d86b2 | 2375 | } |
89cfe6e5 | 2376 | \f |
f0b5f617 | 2377 | /* Predict edges to successors of CUR whose sources are not postdominated by |
d704ea82 | 2378 | BB by PRED and recurse to all postdominators. */ |
f816ec49 | 2379 | |
2380 | static void | |
d704ea82 | 2381 | predict_paths_for_bb (basic_block cur, basic_block bb, |
2382 | enum br_predictor pred, | |
d3443011 | 2383 | enum prediction taken, |
2384 | bitmap visited) | |
f816ec49 | 2385 | { |
2386 | edge e; | |
cd665a06 | 2387 | edge_iterator ei; |
d704ea82 | 2388 | basic_block son; |
f816ec49 | 2389 | |
d704ea82 | 2390 | /* We are looking for all edges forming edge cut induced by |
2391 | set of all blocks postdominated by BB. */ | |
2392 | FOR_EACH_EDGE (e, ei, cur->preds) | |
2393 | if (e->src->index >= NUM_FIXED_BLOCKS | |
2394 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, bb)) | |
f816ec49 | 2395 | { |
f1d5a92b | 2396 | edge e2; |
2397 | edge_iterator ei2; | |
2398 | bool found = false; | |
2399 | ||
5707768a | 2400 | /* Ignore fake edges and eh, we predict them as not taken anyway. */ |
2401 | if (e->flags & (EDGE_EH | EDGE_FAKE)) | |
f1d5a92b | 2402 | continue; |
d704ea82 | 2403 | gcc_assert (bb == cur || dominated_by_p (CDI_POST_DOMINATORS, cur, bb)); |
f1d5a92b | 2404 | |
d3443011 | 2405 | /* See if there is an edge from e->src that is not abnormal |
f1d5a92b | 2406 | and does not lead to BB. */ |
2407 | FOR_EACH_EDGE (e2, ei2, e->src->succs) | |
2408 | if (e2 != e | |
5707768a | 2409 | && !(e2->flags & (EDGE_EH | EDGE_FAKE)) |
f1d5a92b | 2410 | && !dominated_by_p (CDI_POST_DOMINATORS, e2->dest, bb)) |
2411 | { | |
2412 | found = true; | |
2413 | break; | |
2414 | } | |
2415 | ||
2416 | /* If there is non-abnormal path leaving e->src, predict edge | |
2417 | using predictor. Otherwise we need to look for paths | |
d3443011 | 2418 | leading to e->src. |
2419 | ||
2420 | The second may lead to infinite loop in the case we are predicitng | |
2421 | regions that are only reachable by abnormal edges. We simply | |
2422 | prevent visiting given BB twice. */ | |
f1d5a92b | 2423 | if (found) |
2424 | predict_edge_def (e, pred, taken); | |
6e3803fb | 2425 | else if (bitmap_set_bit (visited, e->src->index)) |
d3443011 | 2426 | predict_paths_for_bb (e->src, e->src, pred, taken, visited); |
f816ec49 | 2427 | } |
d704ea82 | 2428 | for (son = first_dom_son (CDI_POST_DOMINATORS, cur); |
2429 | son; | |
2430 | son = next_dom_son (CDI_POST_DOMINATORS, son)) | |
d3443011 | 2431 | predict_paths_for_bb (son, bb, pred, taken, visited); |
d704ea82 | 2432 | } |
f816ec49 | 2433 | |
d704ea82 | 2434 | /* Sets branch probabilities according to PREDiction and |
2435 | FLAGS. */ | |
f816ec49 | 2436 | |
d704ea82 | 2437 | static void |
2438 | predict_paths_leading_to (basic_block bb, enum br_predictor pred, | |
2439 | enum prediction taken) | |
2440 | { | |
d3443011 | 2441 | bitmap visited = BITMAP_ALLOC (NULL); |
2442 | predict_paths_for_bb (bb, bb, pred, taken, visited); | |
2443 | BITMAP_FREE (visited); | |
f816ec49 | 2444 | } |
5707768a | 2445 | |
2446 | /* Like predict_paths_leading_to but take edge instead of basic block. */ | |
2447 | ||
2448 | static void | |
2449 | predict_paths_leading_to_edge (edge e, enum br_predictor pred, | |
2450 | enum prediction taken) | |
2451 | { | |
2452 | bool has_nonloop_edge = false; | |
2453 | edge_iterator ei; | |
2454 | edge e2; | |
2455 | ||
2456 | basic_block bb = e->src; | |
2457 | FOR_EACH_EDGE (e2, ei, bb->succs) | |
2458 | if (e2->dest != e->src && e2->dest != e->dest | |
2459 | && !(e->flags & (EDGE_EH | EDGE_FAKE)) | |
2460 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e2->dest)) | |
2461 | { | |
2462 | has_nonloop_edge = true; | |
2463 | break; | |
2464 | } | |
2465 | if (!has_nonloop_edge) | |
d3443011 | 2466 | { |
2467 | bitmap visited = BITMAP_ALLOC (NULL); | |
2468 | predict_paths_for_bb (bb, bb, pred, taken, visited); | |
2469 | BITMAP_FREE (visited); | |
2470 | } | |
5707768a | 2471 | else |
2472 | predict_edge_def (e, pred, taken); | |
2473 | } | |
cd0fe062 | 2474 | \f |
e725f898 | 2475 | /* This is used to carry information about basic blocks. It is |
f81d9f78 | 2476 | attached to the AUX field of the standard CFG block. */ |
2477 | ||
9908fe4d | 2478 | struct block_info |
f81d9f78 | 2479 | { |
2480 | /* Estimated frequency of execution of basic_block. */ | |
e9d7220b | 2481 | sreal frequency; |
f81d9f78 | 2482 | |
2483 | /* To keep queue of basic blocks to process. */ | |
2484 | basic_block next; | |
2485 | ||
4a82352a | 2486 | /* Number of predecessors we need to visit first. */ |
4ad72a03 | 2487 | int npredecessors; |
9908fe4d | 2488 | }; |
f81d9f78 | 2489 | |
2490 | /* Similar information for edges. */ | |
9908fe4d | 2491 | struct edge_prob_info |
f81d9f78 | 2492 | { |
77aa6362 | 2493 | /* In case edge is a loopback edge, the probability edge will be reached |
f81d9f78 | 2494 | in case header is. Estimated number of iterations of the loop can be |
56ff4880 | 2495 | then computed as 1 / (1 - back_edge_prob). */ |
e9d7220b | 2496 | sreal back_edge_prob; |
77aa6362 | 2497 | /* True if the edge is a loopback edge in the natural loop. */ |
74cbb553 | 2498 | unsigned int back_edge:1; |
9908fe4d | 2499 | }; |
f81d9f78 | 2500 | |
9908fe4d | 2501 | #define BLOCK_INFO(B) ((block_info *) (B)->aux) |
886c1262 | 2502 | #undef EDGE_INFO |
9908fe4d | 2503 | #define EDGE_INFO(E) ((edge_prob_info *) (E)->aux) |
f81d9f78 | 2504 | |
2505 | /* Helper function for estimate_bb_frequencies. | |
88e6f696 | 2506 | Propagate the frequencies in blocks marked in |
2507 | TOVISIT, starting in HEAD. */ | |
e6751e9a | 2508 | |
f81d9f78 | 2509 | static void |
88e6f696 | 2510 | propagate_freq (basic_block head, bitmap tovisit) |
f81d9f78 | 2511 | { |
4c26117a | 2512 | basic_block bb; |
2513 | basic_block last; | |
9ea83aa5 | 2514 | unsigned i; |
f81d9f78 | 2515 | edge e; |
2516 | basic_block nextbb; | |
b1bb9b10 | 2517 | bitmap_iterator bi; |
312866af | 2518 | |
4a82352a | 2519 | /* For each basic block we need to visit count number of his predecessors |
312866af | 2520 | we need to visit first. */ |
b1bb9b10 | 2521 | EXECUTE_IF_SET_IN_BITMAP (tovisit, 0, i, bi) |
312866af | 2522 | { |
b1bb9b10 | 2523 | edge_iterator ei; |
2524 | int count = 0; | |
2525 | ||
f5a6b05f | 2526 | bb = BASIC_BLOCK_FOR_FN (cfun, i); |
e6751e9a | 2527 | |
b1bb9b10 | 2528 | FOR_EACH_EDGE (e, ei, bb->preds) |
2529 | { | |
2530 | bool visit = bitmap_bit_p (tovisit, e->src->index); | |
2531 | ||
2532 | if (visit && !(e->flags & EDGE_DFS_BACK)) | |
2533 | count++; | |
2534 | else if (visit && dump_file && !EDGE_INFO (e)->back_edge) | |
2535 | fprintf (dump_file, | |
2536 | "Irreducible region hit, ignoring edge to %i->%i\n", | |
2537 | e->src->index, bb->index); | |
312866af | 2538 | } |
9ea83aa5 | 2539 | BLOCK_INFO (bb)->npredecessors = count; |
555e8b05 | 2540 | /* When function never returns, we will never process exit block. */ |
34154e27 | 2541 | if (!count && bb == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
555e8b05 | 2542 | bb->count = bb->frequency = 0; |
312866af | 2543 | } |
f81d9f78 | 2544 | |
8201d1f6 | 2545 | BLOCK_INFO (head)->frequency = 1; |
4c26117a | 2546 | last = head; |
2547 | for (bb = head; bb; bb = nextbb) | |
f81d9f78 | 2548 | { |
cd665a06 | 2549 | edge_iterator ei; |
8201d1f6 | 2550 | sreal cyclic_probability = 0; |
2551 | sreal frequency = 0; | |
f81d9f78 | 2552 | |
2553 | nextbb = BLOCK_INFO (bb)->next; | |
2554 | BLOCK_INFO (bb)->next = NULL; | |
2555 | ||
2556 | /* Compute frequency of basic block. */ | |
2557 | if (bb != head) | |
2558 | { | |
312866af | 2559 | #ifdef ENABLE_CHECKING |
cd665a06 | 2560 | FOR_EACH_EDGE (e, ei, bb->preds) |
876760f6 | 2561 | gcc_assert (!bitmap_bit_p (tovisit, e->src->index) |
2562 | || (e->flags & EDGE_DFS_BACK)); | |
312866af | 2563 | #endif |
f81d9f78 | 2564 | |
cd665a06 | 2565 | FOR_EACH_EDGE (e, ei, bb->preds) |
f81d9f78 | 2566 | if (EDGE_INFO (e)->back_edge) |
56ff4880 | 2567 | { |
23a92fc7 | 2568 | cyclic_probability += EDGE_INFO (e)->back_edge_prob; |
56ff4880 | 2569 | } |
312866af | 2570 | else if (!(e->flags & EDGE_DFS_BACK)) |
56ff4880 | 2571 | { |
56ff4880 | 2572 | /* frequency += (e->probability |
2573 | * BLOCK_INFO (e->src)->frequency / | |
2574 | REG_BR_PROB_BASE); */ | |
2575 | ||
8201d1f6 | 2576 | sreal tmp = e->probability; |
23a92fc7 | 2577 | tmp *= BLOCK_INFO (e->src)->frequency; |
2578 | tmp *= real_inv_br_prob_base; | |
2579 | frequency += tmp; | |
56ff4880 | 2580 | } |
2581 | ||
8201d1f6 | 2582 | if (cyclic_probability == 0) |
e9d7220b | 2583 | { |
23a92fc7 | 2584 | BLOCK_INFO (bb)->frequency = frequency; |
e9d7220b | 2585 | } |
2e3c56e8 | 2586 | else |
2587 | { | |
23a92fc7 | 2588 | if (cyclic_probability > real_almost_one) |
2589 | cyclic_probability = real_almost_one; | |
f81d9f78 | 2590 | |
d598ad0d | 2591 | /* BLOCK_INFO (bb)->frequency = frequency |
e9d7220b | 2592 | / (1 - cyclic_probability) */ |
f81d9f78 | 2593 | |
8201d1f6 | 2594 | cyclic_probability = sreal (1) - cyclic_probability; |
23a92fc7 | 2595 | BLOCK_INFO (bb)->frequency = frequency / cyclic_probability; |
2e3c56e8 | 2596 | } |
f81d9f78 | 2597 | } |
2598 | ||
b1bb9b10 | 2599 | bitmap_clear_bit (tovisit, bb->index); |
f81d9f78 | 2600 | |
c6356c17 | 2601 | e = find_edge (bb, head); |
2602 | if (e) | |
2603 | { | |
c6356c17 | 2604 | /* EDGE_INFO (e)->back_edge_prob |
2605 | = ((e->probability * BLOCK_INFO (bb)->frequency) | |
2606 | / REG_BR_PROB_BASE); */ | |
48e1416a | 2607 | |
8201d1f6 | 2608 | sreal tmp = e->probability; |
23a92fc7 | 2609 | tmp *= BLOCK_INFO (bb)->frequency; |
2610 | EDGE_INFO (e)->back_edge_prob = tmp * real_inv_br_prob_base; | |
c6356c17 | 2611 | } |
f81d9f78 | 2612 | |
e725f898 | 2613 | /* Propagate to successor blocks. */ |
cd665a06 | 2614 | FOR_EACH_EDGE (e, ei, bb->succs) |
312866af | 2615 | if (!(e->flags & EDGE_DFS_BACK) |
4ad72a03 | 2616 | && BLOCK_INFO (e->dest)->npredecessors) |
f81d9f78 | 2617 | { |
4ad72a03 | 2618 | BLOCK_INFO (e->dest)->npredecessors--; |
2619 | if (!BLOCK_INFO (e->dest)->npredecessors) | |
312866af | 2620 | { |
2621 | if (!nextbb) | |
2622 | nextbb = e->dest; | |
2623 | else | |
2624 | BLOCK_INFO (last)->next = e->dest; | |
48e1416a | 2625 | |
312866af | 2626 | last = e->dest; |
2627 | } | |
cd665a06 | 2628 | } |
f81d9f78 | 2629 | } |
2630 | } | |
2631 | ||
5327650f | 2632 | /* Estimate frequencies in loops at same nest level. */ |
e6751e9a | 2633 | |
f81d9f78 | 2634 | static void |
88e6f696 | 2635 | estimate_loops_at_level (struct loop *first_loop) |
f81d9f78 | 2636 | { |
7fb12188 | 2637 | struct loop *loop; |
f81d9f78 | 2638 | |
2639 | for (loop = first_loop; loop; loop = loop->next) | |
2640 | { | |
f81d9f78 | 2641 | edge e; |
7fb12188 | 2642 | basic_block *bbs; |
862be747 | 2643 | unsigned i; |
88e6f696 | 2644 | bitmap tovisit = BITMAP_ALLOC (NULL); |
f81d9f78 | 2645 | |
88e6f696 | 2646 | estimate_loops_at_level (loop->inner); |
d598ad0d | 2647 | |
88e6f696 | 2648 | /* Find current loop back edge and mark it. */ |
2649 | e = loop_latch_edge (loop); | |
2650 | EDGE_INFO (e)->back_edge = 1; | |
7fb12188 | 2651 | |
2652 | bbs = get_loop_body (loop); | |
2653 | for (i = 0; i < loop->num_nodes; i++) | |
b1bb9b10 | 2654 | bitmap_set_bit (tovisit, bbs[i]->index); |
7fb12188 | 2655 | free (bbs); |
88e6f696 | 2656 | propagate_freq (loop->header, tovisit); |
2657 | BITMAP_FREE (tovisit); | |
f81d9f78 | 2658 | } |
2659 | } | |
2660 | ||
fa7637bd | 2661 | /* Propagates frequencies through structure of loops. */ |
88e6f696 | 2662 | |
2663 | static void | |
7194de72 | 2664 | estimate_loops (void) |
88e6f696 | 2665 | { |
2666 | bitmap tovisit = BITMAP_ALLOC (NULL); | |
2667 | basic_block bb; | |
2668 | ||
2669 | /* Start by estimating the frequencies in the loops. */ | |
41f75a99 | 2670 | if (number_of_loops (cfun) > 1) |
7194de72 | 2671 | estimate_loops_at_level (current_loops->tree_root->inner); |
88e6f696 | 2672 | |
2673 | /* Now propagate the frequencies through all the blocks. */ | |
ed7d889a | 2674 | FOR_ALL_BB_FN (bb, cfun) |
88e6f696 | 2675 | { |
2676 | bitmap_set_bit (tovisit, bb->index); | |
2677 | } | |
34154e27 | 2678 | propagate_freq (ENTRY_BLOCK_PTR_FOR_FN (cfun), tovisit); |
88e6f696 | 2679 | BITMAP_FREE (tovisit); |
2680 | } | |
2681 | ||
38a65d4e | 2682 | /* Drop the profile for NODE to guessed, and update its frequency based on |
901d3ddc | 2683 | whether it is expected to be hot given the CALL_COUNT. */ |
38a65d4e | 2684 | |
2685 | static void | |
901d3ddc | 2686 | drop_profile (struct cgraph_node *node, gcov_type call_count) |
38a65d4e | 2687 | { |
2688 | struct function *fn = DECL_STRUCT_FUNCTION (node->decl); | |
901d3ddc | 2689 | /* In the case where this was called by another function with a |
2690 | dropped profile, call_count will be 0. Since there are no | |
2691 | non-zero call counts to this function, we don't know for sure | |
2692 | whether it is hot, and therefore it will be marked normal below. */ | |
2693 | bool hot = maybe_hot_count_p (NULL, call_count); | |
38a65d4e | 2694 | |
2695 | if (dump_file) | |
2696 | fprintf (dump_file, | |
2697 | "Dropping 0 profile for %s/%i. %s based on calls.\n", | |
f1c8b4d7 | 2698 | node->name (), node->order, |
38a65d4e | 2699 | hot ? "Function is hot" : "Function is normal"); |
2700 | /* We only expect to miss profiles for functions that are reached | |
2701 | via non-zero call edges in cases where the function may have | |
2702 | been linked from another module or library (COMDATs and extern | |
901d3ddc | 2703 | templates). See the comments below for handle_missing_profiles. |
2704 | Also, only warn in cases where the missing counts exceed the | |
2705 | number of training runs. In certain cases with an execv followed | |
2706 | by a no-return call the profile for the no-return call is not | |
2707 | dumped and there can be a mismatch. */ | |
2708 | if (!DECL_COMDAT (node->decl) && !DECL_EXTERNAL (node->decl) | |
2709 | && call_count > profile_info->runs) | |
38a65d4e | 2710 | { |
2711 | if (flag_profile_correction) | |
2712 | { | |
2713 | if (dump_file) | |
2714 | fprintf (dump_file, | |
2715 | "Missing counts for called function %s/%i\n", | |
f1c8b4d7 | 2716 | node->name (), node->order); |
38a65d4e | 2717 | } |
2718 | else | |
901d3ddc | 2719 | warning (0, "Missing counts for called function %s/%i", |
f1c8b4d7 | 2720 | node->name (), node->order); |
38a65d4e | 2721 | } |
2722 | ||
3bedbae3 | 2723 | profile_status_for_fn (fn) |
38a65d4e | 2724 | = (flag_guess_branch_prob ? PROFILE_GUESSED : PROFILE_ABSENT); |
2725 | node->frequency | |
2726 | = hot ? NODE_FREQUENCY_HOT : NODE_FREQUENCY_NORMAL; | |
2727 | } | |
2728 | ||
2729 | /* In the case of COMDAT routines, multiple object files will contain the same | |
2730 | function and the linker will select one for the binary. In that case | |
2731 | all the other copies from the profile instrument binary will be missing | |
2732 | profile counts. Look for cases where this happened, due to non-zero | |
2733 | call counts going to 0-count functions, and drop the profile to guessed | |
2734 | so that we can use the estimated probabilities and avoid optimizing only | |
2735 | for size. | |
2736 | ||
2737 | The other case where the profile may be missing is when the routine | |
2738 | is not going to be emitted to the object file, e.g. for "extern template" | |
2739 | class methods. Those will be marked DECL_EXTERNAL. Emit a warning in | |
2740 | all other cases of non-zero calls to 0-count functions. */ | |
2741 | ||
2742 | void | |
2743 | handle_missing_profiles (void) | |
2744 | { | |
2745 | struct cgraph_node *node; | |
2746 | int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); | |
2747 | vec<struct cgraph_node *> worklist; | |
2748 | worklist.create (64); | |
2749 | ||
2750 | /* See if 0 count function has non-0 count callers. In this case we | |
2751 | lost some profile. Drop its function profile to PROFILE_GUESSED. */ | |
2752 | FOR_EACH_DEFINED_FUNCTION (node) | |
2753 | { | |
2754 | struct cgraph_edge *e; | |
2755 | gcov_type call_count = 0; | |
af48f0b1 | 2756 | gcov_type max_tp_first_run = 0; |
38a65d4e | 2757 | struct function *fn = DECL_STRUCT_FUNCTION (node->decl); |
2758 | ||
2759 | if (node->count) | |
2760 | continue; | |
2761 | for (e = node->callers; e; e = e->next_caller) | |
af48f0b1 | 2762 | { |
38a65d4e | 2763 | call_count += e->count; |
af48f0b1 | 2764 | |
2765 | if (e->caller->tp_first_run > max_tp_first_run) | |
2766 | max_tp_first_run = e->caller->tp_first_run; | |
2767 | } | |
2768 | ||
2769 | /* If time profile is missing, let assign the maximum that comes from | |
2770 | caller functions. */ | |
2771 | if (!node->tp_first_run && max_tp_first_run) | |
2772 | node->tp_first_run = max_tp_first_run + 1; | |
2773 | ||
38a65d4e | 2774 | if (call_count |
2775 | && fn && fn->cfg | |
2776 | && (call_count * unlikely_count_fraction >= profile_info->runs)) | |
2777 | { | |
901d3ddc | 2778 | drop_profile (node, call_count); |
38a65d4e | 2779 | worklist.safe_push (node); |
2780 | } | |
2781 | } | |
2782 | ||
2783 | /* Propagate the profile dropping to other 0-count COMDATs that are | |
2784 | potentially called by COMDATs we already dropped the profile on. */ | |
2785 | while (worklist.length () > 0) | |
2786 | { | |
2787 | struct cgraph_edge *e; | |
2788 | ||
2789 | node = worklist.pop (); | |
2790 | for (e = node->callees; e; e = e->next_caller) | |
2791 | { | |
2792 | struct cgraph_node *callee = e->callee; | |
2793 | struct function *fn = DECL_STRUCT_FUNCTION (callee->decl); | |
2794 | ||
2795 | if (callee->count > 0) | |
2796 | continue; | |
2797 | if (DECL_COMDAT (callee->decl) && fn && fn->cfg | |
3bedbae3 | 2798 | && profile_status_for_fn (fn) == PROFILE_READ) |
38a65d4e | 2799 | { |
901d3ddc | 2800 | drop_profile (node, 0); |
38a65d4e | 2801 | worklist.safe_push (callee); |
2802 | } | |
2803 | } | |
2804 | } | |
2805 | worklist.release (); | |
2806 | } | |
2807 | ||
3f18719c | 2808 | /* Convert counts measured by profile driven feedback to frequencies. |
2809 | Return nonzero iff there was any nonzero execution count. */ | |
e6751e9a | 2810 | |
ffedd254 | 2811 | int |
d598ad0d | 2812 | counts_to_freqs (void) |
f81d9f78 | 2813 | { |
3f18719c | 2814 | gcov_type count_max, true_count_max = 0; |
4c26117a | 2815 | basic_block bb; |
b3d6de89 | 2816 | |
38a65d4e | 2817 | /* Don't overwrite the estimated frequencies when the profile for |
2818 | the function is missing. We may drop this function PROFILE_GUESSED | |
2819 | later in drop_profile (). */ | |
94bed7c3 | 2820 | if (!flag_auto_profile && !ENTRY_BLOCK_PTR_FOR_FN (cfun)->count) |
38a65d4e | 2821 | return 0; |
2822 | ||
34154e27 | 2823 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
3f18719c | 2824 | true_count_max = MAX (bb->count, true_count_max); |
f81d9f78 | 2825 | |
3f18719c | 2826 | count_max = MAX (true_count_max, 1); |
34154e27 | 2827 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
4c26117a | 2828 | bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max; |
167b550b | 2829 | |
3f18719c | 2830 | return true_count_max; |
f81d9f78 | 2831 | } |
2832 | ||
e6751e9a | 2833 | /* Return true if function is likely to be expensive, so there is no point to |
2834 | optimize performance of prologue, epilogue or do inlining at the expense | |
41a6f238 | 2835 | of code size growth. THRESHOLD is the limit of number of instructions |
e6751e9a | 2836 | function can execute at average to be still considered not expensive. */ |
2837 | ||
f4c0c1a2 | 2838 | bool |
d598ad0d | 2839 | expensive_function_p (int threshold) |
f4c0c1a2 | 2840 | { |
2841 | unsigned int sum = 0; | |
4c26117a | 2842 | basic_block bb; |
27d0c333 | 2843 | unsigned int limit; |
f4c0c1a2 | 2844 | |
2845 | /* We can not compute accurately for large thresholds due to scaled | |
2846 | frequencies. */ | |
876760f6 | 2847 | gcc_assert (threshold <= BB_FREQ_MAX); |
f4c0c1a2 | 2848 | |
4a82352a | 2849 | /* Frequencies are out of range. This either means that function contains |
f4c0c1a2 | 2850 | internal loop executing more than BB_FREQ_MAX times or profile feedback |
2851 | is available and function has not been executed at all. */ | |
34154e27 | 2852 | if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency == 0) |
f4c0c1a2 | 2853 | return true; |
195731ad | 2854 | |
f4c0c1a2 | 2855 | /* Maximally BB_FREQ_MAX^2 so overflow won't happen. */ |
34154e27 | 2856 | limit = ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency * threshold; |
fc00614f | 2857 | FOR_EACH_BB_FN (bb, cfun) |
f4c0c1a2 | 2858 | { |
ee5f6585 | 2859 | rtx_insn *insn; |
f4c0c1a2 | 2860 | |
91f71fa3 | 2861 | FOR_BB_INSNS (bb, insn) |
e6751e9a | 2862 | if (active_insn_p (insn)) |
2863 | { | |
2864 | sum += bb->frequency; | |
2865 | if (sum > limit) | |
2866 | return true; | |
f4c0c1a2 | 2867 | } |
2868 | } | |
e6751e9a | 2869 | |
f4c0c1a2 | 2870 | return false; |
2871 | } | |
2872 | ||
5327650f | 2873 | /* Estimate and propagate basic block frequencies using the given branch |
2874 | probabilities. If FORCE is true, the frequencies are used to estimate | |
2875 | the counts even when there are already non-zero profile counts. */ | |
e6751e9a | 2876 | |
4ae20857 | 2877 | void |
5327650f | 2878 | estimate_bb_frequencies (bool force) |
f81d9f78 | 2879 | { |
4c26117a | 2880 | basic_block bb; |
e9d7220b | 2881 | sreal freq_max; |
56ff4880 | 2882 | |
f26d8580 | 2883 | if (force || profile_status_for_fn (cfun) != PROFILE_READ || !counts_to_freqs ()) |
429fa7fa | 2884 | { |
31e4010e | 2885 | static int real_values_initialized = 0; |
2886 | ||
2887 | if (!real_values_initialized) | |
2888 | { | |
fc22704f | 2889 | real_values_initialized = 1; |
8201d1f6 | 2890 | real_br_prob_base = REG_BR_PROB_BASE; |
2891 | real_bb_freq_max = BB_FREQ_MAX; | |
23a92fc7 | 2892 | real_one_half = sreal (1, -1); |
8201d1f6 | 2893 | real_inv_br_prob_base = sreal (1) / real_br_prob_base; |
2894 | real_almost_one = sreal (1) - real_inv_br_prob_base; | |
31e4010e | 2895 | } |
f81d9f78 | 2896 | |
429fa7fa | 2897 | mark_dfs_back_edges (); |
429fa7fa | 2898 | |
34154e27 | 2899 | single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))->probability = |
2900 | REG_BR_PROB_BASE; | |
429fa7fa | 2901 | |
2902 | /* Set up block info for each basic block. */ | |
9908fe4d | 2903 | alloc_aux_for_blocks (sizeof (block_info)); |
2904 | alloc_aux_for_edges (sizeof (edge_prob_info)); | |
34154e27 | 2905 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
f81d9f78 | 2906 | { |
f81d9f78 | 2907 | edge e; |
cd665a06 | 2908 | edge_iterator ei; |
429fa7fa | 2909 | |
cd665a06 | 2910 | FOR_EACH_EDGE (e, ei, bb->succs) |
f81d9f78 | 2911 | { |
8201d1f6 | 2912 | EDGE_INFO (e)->back_edge_prob = e->probability; |
23a92fc7 | 2913 | EDGE_INFO (e)->back_edge_prob *= real_inv_br_prob_base; |
f81d9f78 | 2914 | } |
f81d9f78 | 2915 | } |
e6751e9a | 2916 | |
5327650f | 2917 | /* First compute frequencies locally for each loop from innermost |
2918 | to outermost to examine frequencies for back edges. */ | |
7194de72 | 2919 | estimate_loops (); |
f81d9f78 | 2920 | |
8201d1f6 | 2921 | freq_max = 0; |
fc00614f | 2922 | FOR_EACH_BB_FN (bb, cfun) |
23a92fc7 | 2923 | if (freq_max < BLOCK_INFO (bb)->frequency) |
2924 | freq_max = BLOCK_INFO (bb)->frequency; | |
2e3c56e8 | 2925 | |
23a92fc7 | 2926 | freq_max = real_bb_freq_max / freq_max; |
34154e27 | 2927 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
56ff4880 | 2928 | { |
23a92fc7 | 2929 | sreal tmp = BLOCK_INFO (bb)->frequency * freq_max + real_one_half; |
2930 | bb->frequency = tmp.to_int (); | |
429fa7fa | 2931 | } |
e6751e9a | 2932 | |
429fa7fa | 2933 | free_aux_for_blocks (); |
2934 | free_aux_for_edges (); | |
2935 | } | |
2936 | compute_function_frequency (); | |
429fa7fa | 2937 | } |
f81d9f78 | 2938 | |
429fa7fa | 2939 | /* Decide whether function is hot, cold or unlikely executed. */ |
63aab97d | 2940 | void |
d598ad0d | 2941 | compute_function_frequency (void) |
429fa7fa | 2942 | { |
4c26117a | 2943 | basic_block bb; |
415d1b9a | 2944 | struct cgraph_node *node = cgraph_node::get (current_function_decl); |
e27f29dd | 2945 | |
0f9fb931 | 2946 | if (DECL_STATIC_CONSTRUCTOR (current_function_decl) |
2947 | || MAIN_NAME_P (DECL_NAME (current_function_decl))) | |
2948 | node->only_called_at_startup = true; | |
2949 | if (DECL_STATIC_DESTRUCTOR (current_function_decl)) | |
2950 | node->only_called_at_exit = true; | |
4c26117a | 2951 | |
f26d8580 | 2952 | if (profile_status_for_fn (cfun) != PROFILE_READ) |
5de92639 | 2953 | { |
125b6d78 | 2954 | int flags = flags_from_decl_or_type (current_function_decl); |
5de92639 | 2955 | if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl)) |
2956 | != NULL) | |
125b6d78 | 2957 | node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; |
5de92639 | 2958 | else if (lookup_attribute ("hot", DECL_ATTRIBUTES (current_function_decl)) |
2959 | != NULL) | |
125b6d78 | 2960 | node->frequency = NODE_FREQUENCY_HOT; |
2961 | else if (flags & ECF_NORETURN) | |
2962 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
2963 | else if (MAIN_NAME_P (DECL_NAME (current_function_decl))) | |
2964 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
2965 | else if (DECL_STATIC_CONSTRUCTOR (current_function_decl) | |
2966 | || DECL_STATIC_DESTRUCTOR (current_function_decl)) | |
2967 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
5de92639 | 2968 | return; |
2969 | } | |
e27f29dd | 2970 | |
2971 | /* Only first time try to drop function into unlikely executed. | |
2972 | After inlining the roundoff errors may confuse us. | |
2973 | Ipa-profile pass will drop functions only called from unlikely | |
2974 | functions to unlikely and that is most of what we care about. */ | |
2975 | if (!cfun->after_inlining) | |
2976 | node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; | |
fc00614f | 2977 | FOR_EACH_BB_FN (bb, cfun) |
f81d9f78 | 2978 | { |
8d672d12 | 2979 | if (maybe_hot_bb_p (cfun, bb)) |
429fa7fa | 2980 | { |
125b6d78 | 2981 | node->frequency = NODE_FREQUENCY_HOT; |
429fa7fa | 2982 | return; |
2983 | } | |
8d672d12 | 2984 | if (!probably_never_executed_bb_p (cfun, bb)) |
125b6d78 | 2985 | node->frequency = NODE_FREQUENCY_NORMAL; |
f81d9f78 | 2986 | } |
429fa7fa | 2987 | } |
f81d9f78 | 2988 | |
4a1849e3 | 2989 | /* Build PREDICT_EXPR. */ |
2990 | tree | |
2991 | build_predict_expr (enum br_predictor predictor, enum prediction taken) | |
2992 | { | |
08f62b1b | 2993 | tree t = build1 (PREDICT_EXPR, void_type_node, |
b3d480fb | 2994 | build_int_cst (integer_type_node, predictor)); |
b9c74b4d | 2995 | SET_PREDICT_EXPR_OUTCOME (t, taken); |
4a1849e3 | 2996 | return t; |
2997 | } | |
2998 | ||
2999 | const char * | |
3000 | predictor_name (enum br_predictor predictor) | |
3001 | { | |
3002 | return predictor_info[predictor].name; | |
3003 | } | |
3004 | ||
65b0537f | 3005 | /* Predict branch probabilities and estimate profile of the tree CFG. */ |
3006 | ||
cbe8bda8 | 3007 | namespace { |
3008 | ||
3009 | const pass_data pass_data_profile = | |
3010 | { | |
3011 | GIMPLE_PASS, /* type */ | |
3012 | "profile_estimate", /* name */ | |
3013 | OPTGROUP_NONE, /* optinfo_flags */ | |
cbe8bda8 | 3014 | TV_BRANCH_PROB, /* tv_id */ |
3015 | PROP_cfg, /* properties_required */ | |
3016 | 0, /* properties_provided */ | |
3017 | 0, /* properties_destroyed */ | |
3018 | 0, /* todo_flags_start */ | |
8b88439e | 3019 | 0, /* todo_flags_finish */ |
4ee9c684 | 3020 | }; |
1add270f | 3021 | |
cbe8bda8 | 3022 | class pass_profile : public gimple_opt_pass |
3023 | { | |
3024 | public: | |
9af5ce0c | 3025 | pass_profile (gcc::context *ctxt) |
3026 | : gimple_opt_pass (pass_data_profile, ctxt) | |
cbe8bda8 | 3027 | {} |
3028 | ||
3029 | /* opt_pass methods: */ | |
31315c24 | 3030 | virtual bool gate (function *) { return flag_guess_branch_prob; } |
65b0537f | 3031 | virtual unsigned int execute (function *); |
cbe8bda8 | 3032 | |
3033 | }; // class pass_profile | |
3034 | ||
65b0537f | 3035 | unsigned int |
3036 | pass_profile::execute (function *fun) | |
3037 | { | |
3038 | unsigned nb_loops; | |
3039 | ||
3a9f48e7 | 3040 | if (profile_status_for_fn (cfun) == PROFILE_GUESSED) |
3041 | return 0; | |
3042 | ||
65b0537f | 3043 | loop_optimizer_init (LOOPS_NORMAL); |
3044 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3045 | flow_loops_dump (dump_file, NULL, 0); | |
3046 | ||
3047 | mark_irreducible_loops (); | |
3048 | ||
3049 | nb_loops = number_of_loops (fun); | |
3050 | if (nb_loops > 1) | |
3051 | scev_initialize (); | |
3052 | ||
3053 | tree_estimate_probability (); | |
3054 | ||
3055 | if (nb_loops > 1) | |
3056 | scev_finalize (); | |
3057 | ||
3058 | loop_optimizer_finalize (); | |
3059 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3060 | gimple_dump_cfg (dump_file, dump_flags); | |
3061 | if (profile_status_for_fn (fun) == PROFILE_ABSENT) | |
3062 | profile_status_for_fn (fun) = PROFILE_GUESSED; | |
3063 | return 0; | |
3064 | } | |
3065 | ||
cbe8bda8 | 3066 | } // anon namespace |
3067 | ||
3068 | gimple_opt_pass * | |
3069 | make_pass_profile (gcc::context *ctxt) | |
3070 | { | |
3071 | return new pass_profile (ctxt); | |
3072 | } | |
3073 | ||
3074 | namespace { | |
3075 | ||
3076 | const pass_data pass_data_strip_predict_hints = | |
3077 | { | |
3078 | GIMPLE_PASS, /* type */ | |
3079 | "*strip_predict_hints", /* name */ | |
3080 | OPTGROUP_NONE, /* optinfo_flags */ | |
cbe8bda8 | 3081 | TV_BRANCH_PROB, /* tv_id */ |
3082 | PROP_cfg, /* properties_required */ | |
3083 | 0, /* properties_provided */ | |
3084 | 0, /* properties_destroyed */ | |
3085 | 0, /* todo_flags_start */ | |
8b88439e | 3086 | 0, /* todo_flags_finish */ |
1add270f | 3087 | }; |
555e8b05 | 3088 | |
cbe8bda8 | 3089 | class pass_strip_predict_hints : public gimple_opt_pass |
3090 | { | |
3091 | public: | |
9af5ce0c | 3092 | pass_strip_predict_hints (gcc::context *ctxt) |
3093 | : gimple_opt_pass (pass_data_strip_predict_hints, ctxt) | |
cbe8bda8 | 3094 | {} |
3095 | ||
3096 | /* opt_pass methods: */ | |
ae84f584 | 3097 | opt_pass * clone () { return new pass_strip_predict_hints (m_ctxt); } |
65b0537f | 3098 | virtual unsigned int execute (function *); |
cbe8bda8 | 3099 | |
3100 | }; // class pass_strip_predict_hints | |
3101 | ||
65b0537f | 3102 | /* Get rid of all builtin_expect calls and GIMPLE_PREDICT statements |
3103 | we no longer need. */ | |
3104 | unsigned int | |
3105 | pass_strip_predict_hints::execute (function *fun) | |
3106 | { | |
3107 | basic_block bb; | |
3108 | gimple ass_stmt; | |
3109 | tree var; | |
3110 | ||
3111 | FOR_EACH_BB_FN (bb, fun) | |
3112 | { | |
3113 | gimple_stmt_iterator bi; | |
3114 | for (bi = gsi_start_bb (bb); !gsi_end_p (bi);) | |
3115 | { | |
3116 | gimple stmt = gsi_stmt (bi); | |
3117 | ||
3118 | if (gimple_code (stmt) == GIMPLE_PREDICT) | |
3119 | { | |
3120 | gsi_remove (&bi, true); | |
3121 | continue; | |
3122 | } | |
3123 | else if (is_gimple_call (stmt)) | |
3124 | { | |
3125 | tree fndecl = gimple_call_fndecl (stmt); | |
3126 | ||
3127 | if ((fndecl | |
3128 | && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL | |
3129 | && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT | |
3130 | && gimple_call_num_args (stmt) == 2) | |
3131 | || (gimple_call_internal_p (stmt) | |
3132 | && gimple_call_internal_fn (stmt) == IFN_BUILTIN_EXPECT)) | |
3133 | { | |
3134 | var = gimple_call_lhs (stmt); | |
3135 | if (var) | |
3136 | { | |
3137 | ass_stmt | |
3138 | = gimple_build_assign (var, gimple_call_arg (stmt, 0)); | |
3139 | gsi_replace (&bi, ass_stmt, true); | |
3140 | } | |
3141 | else | |
3142 | { | |
3143 | gsi_remove (&bi, true); | |
3144 | continue; | |
3145 | } | |
3146 | } | |
3147 | } | |
3148 | gsi_next (&bi); | |
3149 | } | |
3150 | } | |
3151 | return 0; | |
3152 | } | |
3153 | ||
cbe8bda8 | 3154 | } // anon namespace |
3155 | ||
3156 | gimple_opt_pass * | |
3157 | make_pass_strip_predict_hints (gcc::context *ctxt) | |
3158 | { | |
3159 | return new pass_strip_predict_hints (ctxt); | |
3160 | } | |
3161 | ||
555e8b05 | 3162 | /* Rebuild function frequencies. Passes are in general expected to |
3163 | maintain profile by hand, however in some cases this is not possible: | |
3164 | for example when inlining several functions with loops freuqencies might run | |
3165 | out of scale and thus needs to be recomputed. */ | |
3166 | ||
3167 | void | |
3168 | rebuild_frequencies (void) | |
3169 | { | |
4b366dd3 | 3170 | timevar_push (TV_REBUILD_FREQUENCIES); |
5327650f | 3171 | |
3172 | /* When the max bb count in the function is small, there is a higher | |
3173 | chance that there were truncation errors in the integer scaling | |
3174 | of counts by inlining and other optimizations. This could lead | |
3175 | to incorrect classification of code as being cold when it isn't. | |
3176 | In that case, force the estimation of bb counts/frequencies from the | |
3177 | branch probabilities, rather than computing frequencies from counts, | |
3178 | which may also lead to frequencies incorrectly reduced to 0. There | |
3179 | is less precision in the probabilities, so we only do this for small | |
3180 | max counts. */ | |
3181 | gcov_type count_max = 0; | |
3182 | basic_block bb; | |
34154e27 | 3183 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
5327650f | 3184 | count_max = MAX (bb->count, count_max); |
3185 | ||
f26d8580 | 3186 | if (profile_status_for_fn (cfun) == PROFILE_GUESSED |
94bed7c3 | 3187 | || (!flag_auto_profile && profile_status_for_fn (cfun) == PROFILE_READ |
3188 | && count_max < REG_BR_PROB_BASE/10)) | |
555e8b05 | 3189 | { |
3190 | loop_optimizer_init (0); | |
3191 | add_noreturn_fake_exit_edges (); | |
3192 | mark_irreducible_loops (); | |
3193 | connect_infinite_loops_to_exit (); | |
5327650f | 3194 | estimate_bb_frequencies (true); |
555e8b05 | 3195 | remove_fake_exit_edges (); |
3196 | loop_optimizer_finalize (); | |
3197 | } | |
f26d8580 | 3198 | else if (profile_status_for_fn (cfun) == PROFILE_READ) |
555e8b05 | 3199 | counts_to_freqs (); |
3200 | else | |
3201 | gcc_unreachable (); | |
4b366dd3 | 3202 | timevar_pop (TV_REBUILD_FREQUENCIES); |
555e8b05 | 3203 | } |