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59423b59 | 1 | /* Branch prediction routines for the GNU compiler. |
711789cc | 2 | Copyright (C) 2000-2013 Free Software Foundation, Inc. |
59423b59 | 3 | |
e6751e9a | 4 | This file is part of GCC. |
59423b59 | 5 | |
e6751e9a | 6 | GCC is free software; you can redistribute it and/or modify it under |
7 | the terms of the GNU General Public License as published by the Free | |
8c4c00c1 | 8 | Software Foundation; either version 3, or (at your option) any later |
e6751e9a | 9 | version. |
59423b59 | 10 | |
e6751e9a | 11 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 | for more details. | |
59423b59 | 15 | |
e6751e9a | 16 | You should have received a copy of the GNU General Public License |
8c4c00c1 | 17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
59423b59 | 19 | |
20 | /* References: | |
21 | ||
22 | [1] "Branch Prediction for Free" | |
23 | Ball and Larus; PLDI '93. | |
24 | [2] "Static Branch Frequency and Program Profile Analysis" | |
25 | Wu and Larus; MICRO-27. | |
26 | [3] "Corpus-based Static Branch Prediction" | |
04641143 | 27 | Calder, Grunwald, Lindsay, Martin, Mozer, and Zorn; PLDI '95. */ |
59423b59 | 28 | |
29 | ||
30 | #include "config.h" | |
31 | #include "system.h" | |
805e22b2 | 32 | #include "coretypes.h" |
33 | #include "tm.h" | |
59423b59 | 34 | #include "tree.h" |
35 | #include "rtl.h" | |
36 | #include "tm_p.h" | |
d6cb6164 | 37 | #include "hard-reg-set.h" |
59423b59 | 38 | #include "basic-block.h" |
39 | #include "insn-config.h" | |
40 | #include "regs.h" | |
59423b59 | 41 | #include "flags.h" |
59423b59 | 42 | #include "function.h" |
43 | #include "except.h" | |
0b205f4c | 44 | #include "diagnostic-core.h" |
59423b59 | 45 | #include "recog.h" |
59423b59 | 46 | #include "expr.h" |
13488c51 | 47 | #include "predict.h" |
e9fb8a64 | 48 | #include "coverage.h" |
e9d7220b | 49 | #include "sreal.h" |
429fa7fa | 50 | #include "params.h" |
51 | #include "target.h" | |
862be747 | 52 | #include "cfgloop.h" |
073c1fd5 | 53 | #include "gimple.h" |
dcf1a1ec | 54 | #include "gimple-iterator.h" |
073c1fd5 | 55 | #include "gimple-ssa.h" |
56 | #include "cgraph.h" | |
57 | #include "tree-cfg.h" | |
58 | #include "tree-phinodes.h" | |
59 | #include "ssa-iterators.h" | |
05d9c18a | 60 | #include "tree-ssa-loop-niter.h" |
073c1fd5 | 61 | #include "tree-ssa-loop.h" |
4ee9c684 | 62 | #include "ggc.h" |
4ee9c684 | 63 | #include "tree-pass.h" |
d27b0b64 | 64 | #include "tree-scalar-evolution.h" |
65 | #include "cfgloop.h" | |
b3723726 | 66 | #include "pointer-set.h" |
56ff4880 | 67 | |
2e3c56e8 | 68 | /* real constants: 0, 1, 1-1/REG_BR_PROB_BASE, REG_BR_PROB_BASE, |
69 | 1/REG_BR_PROB_BASE, 0.5, BB_FREQ_MAX. */ | |
e9d7220b | 70 | static sreal real_zero, real_one, real_almost_one, real_br_prob_base, |
71 | real_inv_br_prob_base, real_one_half, real_bb_freq_max; | |
59423b59 | 72 | |
48e1416a | 73 | /* Random guesstimation given names. |
fc29fdf5 | 74 | PROV_VERY_UNLIKELY should be small enough so basic block predicted |
3349fabd | 75 | by it gets below HOT_BB_FREQUENCY_FRACTION. */ |
fc29fdf5 | 76 | #define PROB_VERY_UNLIKELY (REG_BR_PROB_BASE / 2000 - 1) |
cfa0194f | 77 | #define PROB_EVEN (REG_BR_PROB_BASE / 2) |
cfa0194f | 78 | #define PROB_VERY_LIKELY (REG_BR_PROB_BASE - PROB_VERY_UNLIKELY) |
79 | #define PROB_ALWAYS (REG_BR_PROB_BASE) | |
59423b59 | 80 | |
d598ad0d | 81 | static void combine_predictions_for_insn (rtx, basic_block); |
4ee9c684 | 82 | static void dump_prediction (FILE *, enum br_predictor, int, basic_block, int); |
d704ea82 | 83 | static void predict_paths_leading_to (basic_block, enum br_predictor, enum prediction); |
5707768a | 84 | static void predict_paths_leading_to_edge (edge, enum br_predictor, enum prediction); |
7ecb5bb2 | 85 | static bool can_predict_insn_p (const_rtx); |
5e96f51e | 86 | |
13488c51 | 87 | /* Information we hold about each branch predictor. |
88 | Filled using information from predict.def. */ | |
e6751e9a | 89 | |
13488c51 | 90 | struct predictor_info |
5e96f51e | 91 | { |
e99c3a1d | 92 | const char *const name; /* Name used in the debugging dumps. */ |
93 | const int hitrate; /* Expected hitrate used by | |
94 | predict_insn_def call. */ | |
95 | const int flags; | |
13488c51 | 96 | }; |
5e96f51e | 97 | |
eb429644 | 98 | /* Use given predictor without Dempster-Shaffer theory if it matches |
99 | using first_match heuristics. */ | |
100 | #define PRED_FLAG_FIRST_MATCH 1 | |
101 | ||
102 | /* Recompute hitrate in percent to our representation. */ | |
103 | ||
e6751e9a | 104 | #define HITRATE(VAL) ((int) ((VAL) * REG_BR_PROB_BASE + 50) / 100) |
eb429644 | 105 | |
106 | #define DEF_PREDICTOR(ENUM, NAME, HITRATE, FLAGS) {NAME, HITRATE, FLAGS}, | |
e6751e9a | 107 | static const struct predictor_info predictor_info[]= { |
13488c51 | 108 | #include "predict.def" |
109 | ||
aa40f561 | 110 | /* Upper bound on predictors. */ |
eb429644 | 111 | {NULL, 0, 0} |
13488c51 | 112 | }; |
113 | #undef DEF_PREDICTOR | |
429fa7fa | 114 | |
eb7df8c2 | 115 | /* Return TRUE if frequency FREQ is considered to be hot. */ |
f29b326e | 116 | |
117 | static inline bool | |
8d672d12 | 118 | maybe_hot_frequency_p (struct function *fun, int freq) |
eb7df8c2 | 119 | { |
8d672d12 | 120 | struct cgraph_node *node = cgraph_get_node (fun->decl); |
eb7df8c2 | 121 | if (!profile_info || !flag_branch_probabilities) |
122 | { | |
125b6d78 | 123 | if (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED) |
eb7df8c2 | 124 | return false; |
125b6d78 | 125 | if (node->frequency == NODE_FREQUENCY_HOT) |
eb7df8c2 | 126 | return true; |
127 | } | |
8d672d12 | 128 | if (profile_status_for_function (fun) == PROFILE_ABSENT) |
aa5f4f32 | 129 | return true; |
125b6d78 | 130 | if (node->frequency == NODE_FREQUENCY_EXECUTED_ONCE |
8d672d12 | 131 | && freq < (ENTRY_BLOCK_PTR_FOR_FUNCTION (fun)->frequency * 2 / 3)) |
125b6d78 | 132 | return false; |
6040d650 | 133 | if (PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) == 0) |
134 | return false; | |
8d672d12 | 135 | if (freq < (ENTRY_BLOCK_PTR_FOR_FUNCTION (fun)->frequency |
136 | / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))) | |
eb7df8c2 | 137 | return false; |
138 | return true; | |
139 | } | |
140 | ||
9e179a64 | 141 | static gcov_type min_count = -1; |
142 | ||
143 | /* Determine the threshold for hot BB counts. */ | |
144 | ||
145 | gcov_type | |
146 | get_hot_bb_threshold () | |
147 | { | |
148 | gcov_working_set_t *ws; | |
149 | if (min_count == -1) | |
150 | { | |
151 | ws = find_working_set (PARAM_VALUE (HOT_BB_COUNT_WS_PERMILLE)); | |
152 | gcc_assert (ws); | |
153 | min_count = ws->min_counter; | |
154 | } | |
155 | return min_count; | |
156 | } | |
157 | ||
158 | /* Set the threshold for hot BB counts. */ | |
159 | ||
160 | void | |
161 | set_hot_bb_threshold (gcov_type min) | |
162 | { | |
163 | min_count = min; | |
164 | } | |
165 | ||
f29b326e | 166 | /* Return TRUE if frequency FREQ is considered to be hot. */ |
167 | ||
168 | static inline bool | |
8d672d12 | 169 | maybe_hot_count_p (struct function *fun, gcov_type count) |
f29b326e | 170 | { |
f34acf02 | 171 | if (fun && profile_status_for_function (fun) != PROFILE_READ) |
f29b326e | 172 | return true; |
173 | /* Code executed at most once is not hot. */ | |
174 | if (profile_info->runs >= count) | |
175 | return false; | |
9e179a64 | 176 | return (count >= get_hot_bb_threshold ()); |
f29b326e | 177 | } |
178 | ||
429fa7fa | 179 | /* Return true in case BB can be CPU intensive and should be optimized |
41a6f238 | 180 | for maximal performance. */ |
429fa7fa | 181 | |
182 | bool | |
8d672d12 | 183 | maybe_hot_bb_p (struct function *fun, const_basic_block bb) |
429fa7fa | 184 | { |
8d672d12 | 185 | gcc_checking_assert (fun); |
186 | if (profile_status_for_function (fun) == PROFILE_READ) | |
187 | return maybe_hot_count_p (fun, bb->count); | |
188 | return maybe_hot_frequency_p (fun, bb->frequency); | |
eb7df8c2 | 189 | } |
190 | ||
11b73810 | 191 | /* Return true if the call can be hot. */ |
192 | ||
193 | bool | |
194 | cgraph_maybe_hot_edge_p (struct cgraph_edge *edge) | |
195 | { | |
196 | if (profile_info && flag_branch_probabilities | |
f34acf02 | 197 | && !maybe_hot_count_p (NULL, |
198 | edge->count)) | |
11b73810 | 199 | return false; |
125b6d78 | 200 | if (edge->caller->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED |
eb7c606e | 201 | || (edge->callee |
202 | && edge->callee->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED)) | |
125b6d78 | 203 | return false; |
7a936ef2 | 204 | if (edge->caller->frequency > NODE_FREQUENCY_UNLIKELY_EXECUTED |
eb7c606e | 205 | && (edge->callee |
206 | && edge->callee->frequency <= NODE_FREQUENCY_EXECUTED_ONCE)) | |
7a936ef2 | 207 | return false; |
125b6d78 | 208 | if (optimize_size) |
11b73810 | 209 | return false; |
125b6d78 | 210 | if (edge->caller->frequency == NODE_FREQUENCY_HOT) |
11b73810 | 211 | return true; |
125b6d78 | 212 | if (edge->caller->frequency == NODE_FREQUENCY_EXECUTED_ONCE |
213 | && edge->frequency < CGRAPH_FREQ_BASE * 3 / 2) | |
214 | return false; | |
6040d650 | 215 | if (flag_guess_branch_prob) |
216 | { | |
217 | if (PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) == 0 | |
218 | || edge->frequency <= (CGRAPH_FREQ_BASE | |
219 | / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))) | |
220 | return false; | |
221 | } | |
11b73810 | 222 | return true; |
223 | } | |
224 | ||
eb7df8c2 | 225 | /* Return true in case BB can be CPU intensive and should be optimized |
226 | for maximal performance. */ | |
227 | ||
228 | bool | |
229 | maybe_hot_edge_p (edge e) | |
230 | { | |
d72cadac | 231 | if (profile_status == PROFILE_READ) |
8d672d12 | 232 | return maybe_hot_count_p (cfun, e->count); |
233 | return maybe_hot_frequency_p (cfun, EDGE_FREQUENCY (e)); | |
429fa7fa | 234 | } |
235 | ||
cf262be9 | 236 | |
cf262be9 | 237 | |
dcc9b351 | 238 | /* Return true if profile COUNT and FREQUENCY, or function FUN static |
239 | node frequency reflects never being executed. */ | |
240 | ||
241 | static bool | |
242 | probably_never_executed (struct function *fun, | |
243 | gcov_type count, int frequency) | |
429fa7fa | 244 | { |
8d672d12 | 245 | gcc_checking_assert (fun); |
4befb9f4 | 246 | if (profile_status_for_function (fun) == PROFILE_READ) |
247 | { | |
c1acf60c | 248 | int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); |
249 | if (count * unlikely_count_fraction >= profile_info->runs) | |
4befb9f4 | 250 | return false; |
dcc9b351 | 251 | if (!frequency) |
4befb9f4 | 252 | return true; |
253 | if (!ENTRY_BLOCK_PTR->frequency) | |
254 | return false; | |
c1acf60c | 255 | if (ENTRY_BLOCK_PTR->count) |
4befb9f4 | 256 | { |
c1acf60c | 257 | gcov_type computed_count; |
258 | /* Check for possibility of overflow, in which case entry bb count | |
259 | is large enough to do the division first without losing much | |
260 | precision. */ | |
261 | if (ENTRY_BLOCK_PTR->count < REG_BR_PROB_BASE * REG_BR_PROB_BASE) | |
262 | { | |
263 | gcov_type scaled_count | |
264 | = frequency * ENTRY_BLOCK_PTR->count * unlikely_count_fraction; | |
265 | computed_count = RDIV (scaled_count, ENTRY_BLOCK_PTR->frequency); | |
266 | } | |
267 | else | |
268 | { | |
269 | computed_count = RDIV (ENTRY_BLOCK_PTR->count, | |
270 | ENTRY_BLOCK_PTR->frequency); | |
271 | computed_count *= frequency * unlikely_count_fraction; | |
272 | } | |
273 | if (computed_count >= profile_info->runs) | |
274 | return false; | |
4befb9f4 | 275 | } |
276 | return true; | |
277 | } | |
5de92639 | 278 | if ((!profile_info || !flag_branch_probabilities) |
8d672d12 | 279 | && (cgraph_get_node (fun->decl)->frequency |
fd6a3c41 | 280 | == NODE_FREQUENCY_UNLIKELY_EXECUTED)) |
5de92639 | 281 | return true; |
429fa7fa | 282 | return false; |
283 | } | |
284 | ||
80adc5a6 | 285 | |
dcc9b351 | 286 | /* Return true in case BB is probably never executed. */ |
287 | ||
288 | bool | |
289 | probably_never_executed_bb_p (struct function *fun, const_basic_block bb) | |
290 | { | |
291 | return probably_never_executed (fun, bb->count, bb->frequency); | |
292 | } | |
293 | ||
294 | ||
80adc5a6 | 295 | /* Return true in case edge E is probably never executed. */ |
296 | ||
297 | bool | |
298 | probably_never_executed_edge_p (struct function *fun, edge e) | |
299 | { | |
dcc9b351 | 300 | return probably_never_executed (fun, e->count, EDGE_FREQUENCY (e)); |
80adc5a6 | 301 | } |
302 | ||
cf262be9 | 303 | /* Return true if NODE should be optimized for size. */ |
7dfb44a0 | 304 | |
533af0db | 305 | bool |
cf262be9 | 306 | cgraph_optimize_for_size_p (struct cgraph_node *node) |
7dfb44a0 | 307 | { |
924de091 | 308 | if (optimize_size) |
309 | return true; | |
924de091 | 310 | if (node && (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED)) |
311 | return true; | |
312 | else | |
313 | return false; | |
533af0db | 314 | } |
315 | ||
cf262be9 | 316 | /* Return true when current function should always be optimized for size. */ |
317 | ||
318 | bool | |
319 | optimize_function_for_size_p (struct function *fun) | |
320 | { | |
321 | if (optimize_size) | |
322 | return true; | |
323 | if (!fun || !fun->decl) | |
324 | return false; | |
325 | return cgraph_optimize_for_size_p (cgraph_get_node (fun->decl)); | |
326 | } | |
327 | ||
533af0db | 328 | /* Return true when current function should always be optimized for speed. */ |
329 | ||
330 | bool | |
331 | optimize_function_for_speed_p (struct function *fun) | |
332 | { | |
333 | return !optimize_function_for_size_p (fun); | |
7dfb44a0 | 334 | } |
335 | ||
336 | /* Return TRUE when BB should be optimized for size. */ | |
337 | ||
338 | bool | |
94ba1cf1 | 339 | optimize_bb_for_size_p (const_basic_block bb) |
7dfb44a0 | 340 | { |
8d672d12 | 341 | return optimize_function_for_size_p (cfun) || !maybe_hot_bb_p (cfun, bb); |
7dfb44a0 | 342 | } |
343 | ||
344 | /* Return TRUE when BB should be optimized for speed. */ | |
345 | ||
346 | bool | |
94ba1cf1 | 347 | optimize_bb_for_speed_p (const_basic_block bb) |
7dfb44a0 | 348 | { |
349 | return !optimize_bb_for_size_p (bb); | |
350 | } | |
351 | ||
352 | /* Return TRUE when BB should be optimized for size. */ | |
353 | ||
354 | bool | |
355 | optimize_edge_for_size_p (edge e) | |
356 | { | |
533af0db | 357 | return optimize_function_for_size_p (cfun) || !maybe_hot_edge_p (e); |
7dfb44a0 | 358 | } |
359 | ||
360 | /* Return TRUE when BB should be optimized for speed. */ | |
361 | ||
362 | bool | |
363 | optimize_edge_for_speed_p (edge e) | |
364 | { | |
365 | return !optimize_edge_for_size_p (e); | |
366 | } | |
367 | ||
368 | /* Return TRUE when BB should be optimized for size. */ | |
369 | ||
370 | bool | |
371 | optimize_insn_for_size_p (void) | |
372 | { | |
533af0db | 373 | return optimize_function_for_size_p (cfun) || !crtl->maybe_hot_insn_p; |
7dfb44a0 | 374 | } |
375 | ||
376 | /* Return TRUE when BB should be optimized for speed. */ | |
377 | ||
378 | bool | |
379 | optimize_insn_for_speed_p (void) | |
380 | { | |
381 | return !optimize_insn_for_size_p (); | |
382 | } | |
383 | ||
94ba1cf1 | 384 | /* Return TRUE when LOOP should be optimized for size. */ |
385 | ||
386 | bool | |
387 | optimize_loop_for_size_p (struct loop *loop) | |
388 | { | |
389 | return optimize_bb_for_size_p (loop->header); | |
390 | } | |
391 | ||
392 | /* Return TRUE when LOOP should be optimized for speed. */ | |
393 | ||
394 | bool | |
395 | optimize_loop_for_speed_p (struct loop *loop) | |
396 | { | |
397 | return optimize_bb_for_speed_p (loop->header); | |
398 | } | |
399 | ||
0bfd8d5c | 400 | /* Return TRUE when LOOP nest should be optimized for speed. */ |
401 | ||
402 | bool | |
403 | optimize_loop_nest_for_speed_p (struct loop *loop) | |
404 | { | |
405 | struct loop *l = loop; | |
406 | if (optimize_loop_for_speed_p (loop)) | |
407 | return true; | |
408 | l = loop->inner; | |
53be41ae | 409 | while (l && l != loop) |
0bfd8d5c | 410 | { |
411 | if (optimize_loop_for_speed_p (l)) | |
412 | return true; | |
413 | if (l->inner) | |
414 | l = l->inner; | |
415 | else if (l->next) | |
416 | l = l->next; | |
417 | else | |
7baffbd3 | 418 | { |
419 | while (l != loop && !l->next) | |
420 | l = loop_outer (l); | |
421 | if (l != loop) | |
422 | l = l->next; | |
423 | } | |
0bfd8d5c | 424 | } |
425 | return false; | |
426 | } | |
427 | ||
428 | /* Return TRUE when LOOP nest should be optimized for size. */ | |
429 | ||
430 | bool | |
431 | optimize_loop_nest_for_size_p (struct loop *loop) | |
432 | { | |
433 | return !optimize_loop_nest_for_speed_p (loop); | |
434 | } | |
435 | ||
4a9d7ef7 | 436 | /* Return true when edge E is likely to be well predictable by branch |
437 | predictor. */ | |
438 | ||
439 | bool | |
440 | predictable_edge_p (edge e) | |
441 | { | |
442 | if (profile_status == PROFILE_ABSENT) | |
443 | return false; | |
444 | if ((e->probability | |
445 | <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100) | |
446 | || (REG_BR_PROB_BASE - e->probability | |
447 | <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100)) | |
448 | return true; | |
449 | return false; | |
450 | } | |
451 | ||
452 | ||
7dfb44a0 | 453 | /* Set RTL expansion for BB profile. */ |
454 | ||
455 | void | |
456 | rtl_profile_for_bb (basic_block bb) | |
457 | { | |
8d672d12 | 458 | crtl->maybe_hot_insn_p = maybe_hot_bb_p (cfun, bb); |
7dfb44a0 | 459 | } |
460 | ||
461 | /* Set RTL expansion for edge profile. */ | |
462 | ||
463 | void | |
464 | rtl_profile_for_edge (edge e) | |
465 | { | |
466 | crtl->maybe_hot_insn_p = maybe_hot_edge_p (e); | |
467 | } | |
468 | ||
469 | /* Set RTL expansion to default mode (i.e. when profile info is not known). */ | |
470 | void | |
471 | default_rtl_profile (void) | |
472 | { | |
473 | crtl->maybe_hot_insn_p = true; | |
474 | } | |
475 | ||
cd0fe062 | 476 | /* Return true if the one of outgoing edges is already predicted by |
477 | PREDICTOR. */ | |
478 | ||
4ee9c684 | 479 | bool |
5493cb9a | 480 | rtl_predicted_by_p (const_basic_block bb, enum br_predictor predictor) |
cd0fe062 | 481 | { |
482 | rtx note; | |
5496dbfc | 483 | if (!INSN_P (BB_END (bb))) |
cd0fe062 | 484 | return false; |
5496dbfc | 485 | for (note = REG_NOTES (BB_END (bb)); note; note = XEXP (note, 1)) |
cd0fe062 | 486 | if (REG_NOTE_KIND (note) == REG_BR_PRED |
487 | && INTVAL (XEXP (XEXP (note, 0), 0)) == (int)predictor) | |
488 | return true; | |
489 | return false; | |
490 | } | |
5e96f51e | 491 | |
b3723726 | 492 | /* This map contains for a basic block the list of predictions for the |
493 | outgoing edges. */ | |
494 | ||
495 | static struct pointer_map_t *bb_predictions; | |
496 | ||
eeb030c4 | 497 | /* Structure representing predictions in tree level. */ |
498 | ||
499 | struct edge_prediction { | |
500 | struct edge_prediction *ep_next; | |
501 | edge ep_edge; | |
502 | enum br_predictor ep_predictor; | |
503 | int ep_probability; | |
504 | }; | |
505 | ||
4ee9c684 | 506 | /* Return true if the one of outgoing edges is already predicted by |
507 | PREDICTOR. */ | |
508 | ||
509 | bool | |
75a70cf9 | 510 | gimple_predicted_by_p (const_basic_block bb, enum br_predictor predictor) |
4ee9c684 | 511 | { |
7ea47fbd | 512 | struct edge_prediction *i; |
b3723726 | 513 | void **preds = pointer_map_contains (bb_predictions, bb); |
514 | ||
515 | if (!preds) | |
516 | return false; | |
48e1416a | 517 | |
4077bf7a | 518 | for (i = (struct edge_prediction *) *preds; i; i = i->ep_next) |
f45e9182 | 519 | if (i->ep_predictor == predictor) |
4ee9c684 | 520 | return true; |
521 | return false; | |
522 | } | |
523 | ||
b41438e5 | 524 | /* Return true when the probability of edge is reliable. |
48e1416a | 525 | |
b41438e5 | 526 | The profile guessing code is good at predicting branch outcome (ie. |
527 | taken/not taken), that is predicted right slightly over 75% of time. | |
ab4f0a13 | 528 | It is however notoriously poor on predicting the probability itself. |
b41438e5 | 529 | In general the profile appear a lot flatter (with probabilities closer |
530 | to 50%) than the reality so it is bad idea to use it to drive optimization | |
531 | such as those disabling dynamic branch prediction for well predictable | |
532 | branches. | |
533 | ||
534 | There are two exceptions - edges leading to noreturn edges and edges | |
535 | predicted by number of iterations heuristics are predicted well. This macro | |
536 | should be able to distinguish those, but at the moment it simply check for | |
537 | noreturn heuristic that is only one giving probability over 99% or bellow | |
ab4f0a13 | 538 | 1%. In future we might want to propagate reliability information across the |
b41438e5 | 539 | CFG if we find this information useful on multiple places. */ |
540 | static bool | |
541 | probability_reliable_p (int prob) | |
542 | { | |
543 | return (profile_status == PROFILE_READ | |
544 | || (profile_status == PROFILE_GUESSED | |
545 | && (prob <= HITRATE (1) || prob >= HITRATE (99)))); | |
546 | } | |
547 | ||
548 | /* Same predicate as above, working on edges. */ | |
549 | bool | |
7ecb5bb2 | 550 | edge_probability_reliable_p (const_edge e) |
b41438e5 | 551 | { |
552 | return probability_reliable_p (e->probability); | |
553 | } | |
554 | ||
555 | /* Same predicate as edge_probability_reliable_p, working on notes. */ | |
556 | bool | |
7ecb5bb2 | 557 | br_prob_note_reliable_p (const_rtx note) |
b41438e5 | 558 | { |
559 | gcc_assert (REG_NOTE_KIND (note) == REG_BR_PROB); | |
9eb946de | 560 | return probability_reliable_p (XINT (note, 0)); |
b41438e5 | 561 | } |
562 | ||
aa157ca4 | 563 | static void |
d598ad0d | 564 | predict_insn (rtx insn, enum br_predictor predictor, int probability) |
13488c51 | 565 | { |
876760f6 | 566 | gcc_assert (any_condjump_p (insn)); |
b28bedce | 567 | if (!flag_guess_branch_prob) |
568 | return; | |
e6751e9a | 569 | |
a1ddb869 | 570 | add_reg_note (insn, REG_BR_PRED, |
571 | gen_rtx_CONCAT (VOIDmode, | |
572 | GEN_INT ((int) predictor), | |
573 | GEN_INT ((int) probability))); | |
13488c51 | 574 | } |
575 | ||
576 | /* Predict insn by given predictor. */ | |
e6751e9a | 577 | |
13488c51 | 578 | void |
d598ad0d | 579 | predict_insn_def (rtx insn, enum br_predictor predictor, |
580 | enum prediction taken) | |
13488c51 | 581 | { |
582 | int probability = predictor_info[(int) predictor].hitrate; | |
e6751e9a | 583 | |
13488c51 | 584 | if (taken != TAKEN) |
585 | probability = REG_BR_PROB_BASE - probability; | |
e6751e9a | 586 | |
13488c51 | 587 | predict_insn (insn, predictor, probability); |
5e96f51e | 588 | } |
589 | ||
590 | /* Predict edge E with given probability if possible. */ | |
e6751e9a | 591 | |
13488c51 | 592 | void |
4ee9c684 | 593 | rtl_predict_edge (edge e, enum br_predictor predictor, int probability) |
5e96f51e | 594 | { |
595 | rtx last_insn; | |
5496dbfc | 596 | last_insn = BB_END (e->src); |
5e96f51e | 597 | |
598 | /* We can store the branch prediction information only about | |
599 | conditional jumps. */ | |
600 | if (!any_condjump_p (last_insn)) | |
601 | return; | |
602 | ||
603 | /* We always store probability of branching. */ | |
604 | if (e->flags & EDGE_FALLTHRU) | |
605 | probability = REG_BR_PROB_BASE - probability; | |
606 | ||
13488c51 | 607 | predict_insn (last_insn, predictor, probability); |
608 | } | |
609 | ||
4ee9c684 | 610 | /* Predict edge E with the given PROBABILITY. */ |
611 | void | |
75a70cf9 | 612 | gimple_predict_edge (edge e, enum br_predictor predictor, int probability) |
4ee9c684 | 613 | { |
d5043f32 | 614 | gcc_assert (profile_status != PROFILE_GUESSED); |
ebd65d12 | 615 | if ((e->src != ENTRY_BLOCK_PTR && EDGE_COUNT (e->src->succs) > 1) |
d5043f32 | 616 | && flag_guess_branch_prob && optimize) |
ebd65d12 | 617 | { |
b3723726 | 618 | struct edge_prediction *i = XNEW (struct edge_prediction); |
619 | void **preds = pointer_map_insert (bb_predictions, e->src); | |
4ee9c684 | 620 | |
4077bf7a | 621 | i->ep_next = (struct edge_prediction *) *preds; |
b3723726 | 622 | *preds = i; |
f45e9182 | 623 | i->ep_probability = probability; |
624 | i->ep_predictor = predictor; | |
625 | i->ep_edge = e; | |
ebd65d12 | 626 | } |
4ee9c684 | 627 | } |
628 | ||
631fa7de | 629 | /* Remove all predictions on given basic block that are attached |
630 | to edge E. */ | |
631 | void | |
632 | remove_predictions_associated_with_edge (edge e) | |
633 | { | |
b3723726 | 634 | void **preds; |
48e1416a | 635 | |
b3723726 | 636 | if (!bb_predictions) |
637 | return; | |
638 | ||
639 | preds = pointer_map_contains (bb_predictions, e->src); | |
640 | ||
641 | if (preds) | |
631fa7de | 642 | { |
b3723726 | 643 | struct edge_prediction **prediction = (struct edge_prediction **) preds; |
644 | struct edge_prediction *next; | |
645 | ||
631fa7de | 646 | while (*prediction) |
647 | { | |
f45e9182 | 648 | if ((*prediction)->ep_edge == e) |
b3723726 | 649 | { |
650 | next = (*prediction)->ep_next; | |
651 | free (*prediction); | |
652 | *prediction = next; | |
653 | } | |
631fa7de | 654 | else |
f45e9182 | 655 | prediction = &((*prediction)->ep_next); |
631fa7de | 656 | } |
657 | } | |
658 | } | |
659 | ||
b3723726 | 660 | /* Clears the list of predictions stored for BB. */ |
661 | ||
662 | static void | |
663 | clear_bb_predictions (basic_block bb) | |
664 | { | |
665 | void **preds = pointer_map_contains (bb_predictions, bb); | |
666 | struct edge_prediction *pred, *next; | |
667 | ||
668 | if (!preds) | |
669 | return; | |
670 | ||
4077bf7a | 671 | for (pred = (struct edge_prediction *) *preds; pred; pred = next) |
b3723726 | 672 | { |
673 | next = pred->ep_next; | |
674 | free (pred); | |
675 | } | |
676 | *preds = NULL; | |
677 | } | |
678 | ||
1a12dac4 | 679 | /* Return true when we can store prediction on insn INSN. |
680 | At the moment we represent predictions only on conditional | |
681 | jumps, not at computed jump or other complicated cases. */ | |
682 | static bool | |
7ecb5bb2 | 683 | can_predict_insn_p (const_rtx insn) |
1a12dac4 | 684 | { |
6d7dc5b9 | 685 | return (JUMP_P (insn) |
1a12dac4 | 686 | && any_condjump_p (insn) |
cd665a06 | 687 | && EDGE_COUNT (BLOCK_FOR_INSN (insn)->succs) >= 2); |
1a12dac4 | 688 | } |
689 | ||
13488c51 | 690 | /* Predict edge E by given predictor if possible. */ |
e6751e9a | 691 | |
13488c51 | 692 | void |
d598ad0d | 693 | predict_edge_def (edge e, enum br_predictor predictor, |
694 | enum prediction taken) | |
13488c51 | 695 | { |
696 | int probability = predictor_info[(int) predictor].hitrate; | |
697 | ||
698 | if (taken != TAKEN) | |
699 | probability = REG_BR_PROB_BASE - probability; | |
e6751e9a | 700 | |
13488c51 | 701 | predict_edge (e, predictor, probability); |
702 | } | |
703 | ||
704 | /* Invert all branch predictions or probability notes in the INSN. This needs | |
705 | to be done each time we invert the condition used by the jump. */ | |
e6751e9a | 706 | |
13488c51 | 707 | void |
d598ad0d | 708 | invert_br_probabilities (rtx insn) |
13488c51 | 709 | { |
e6751e9a | 710 | rtx note; |
711 | ||
712 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) | |
713 | if (REG_NOTE_KIND (note) == REG_BR_PROB) | |
9eb946de | 714 | XINT (note, 0) = REG_BR_PROB_BASE - XINT (note, 0); |
e6751e9a | 715 | else if (REG_NOTE_KIND (note) == REG_BR_PRED) |
716 | XEXP (XEXP (note, 0), 1) | |
717 | = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (XEXP (note, 0), 1))); | |
13488c51 | 718 | } |
719 | ||
720 | /* Dump information about the branch prediction to the output file. */ | |
e6751e9a | 721 | |
13488c51 | 722 | static void |
4ee9c684 | 723 | dump_prediction (FILE *file, enum br_predictor predictor, int probability, |
d598ad0d | 724 | basic_block bb, int used) |
13488c51 | 725 | { |
cd665a06 | 726 | edge e; |
727 | edge_iterator ei; | |
13488c51 | 728 | |
4ee9c684 | 729 | if (!file) |
13488c51 | 730 | return; |
731 | ||
cd665a06 | 732 | FOR_EACH_EDGE (e, ei, bb->succs) |
733 | if (! (e->flags & EDGE_FALLTHRU)) | |
734 | break; | |
13488c51 | 735 | |
4ee9c684 | 736 | fprintf (file, " %s heuristics%s: %.1f%%", |
13488c51 | 737 | predictor_info[predictor].name, |
e6751e9a | 738 | used ? "" : " (ignored)", probability * 100.0 / REG_BR_PROB_BASE); |
13488c51 | 739 | |
740 | if (bb->count) | |
17a81216 | 741 | { |
4ee9c684 | 742 | fprintf (file, " exec "); |
743 | fprintf (file, HOST_WIDEST_INT_PRINT_DEC, bb->count); | |
12c94d25 | 744 | if (e) |
745 | { | |
4ee9c684 | 746 | fprintf (file, " hit "); |
747 | fprintf (file, HOST_WIDEST_INT_PRINT_DEC, e->count); | |
748 | fprintf (file, " (%.1f%%)", e->count * 100.0 / bb->count); | |
12c94d25 | 749 | } |
17a81216 | 750 | } |
e6751e9a | 751 | |
4ee9c684 | 752 | fprintf (file, "\n"); |
13488c51 | 753 | } |
754 | ||
7edd21a5 | 755 | /* We can not predict the probabilities of outgoing edges of bb. Set them |
83c8a977 | 756 | evenly and hope for the best. */ |
757 | static void | |
758 | set_even_probabilities (basic_block bb) | |
759 | { | |
760 | int nedges = 0; | |
761 | edge e; | |
cd665a06 | 762 | edge_iterator ei; |
83c8a977 | 763 | |
cd665a06 | 764 | FOR_EACH_EDGE (e, ei, bb->succs) |
83c8a977 | 765 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
766 | nedges ++; | |
cd665a06 | 767 | FOR_EACH_EDGE (e, ei, bb->succs) |
83c8a977 | 768 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
769 | e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges; | |
770 | else | |
771 | e->probability = 0; | |
772 | } | |
773 | ||
13488c51 | 774 | /* Combine all REG_BR_PRED notes into single probability and attach REG_BR_PROB |
775 | note if not already present. Remove now useless REG_BR_PRED notes. */ | |
e6751e9a | 776 | |
13488c51 | 777 | static void |
d598ad0d | 778 | combine_predictions_for_insn (rtx insn, basic_block bb) |
13488c51 | 779 | { |
83c8a977 | 780 | rtx prob_note; |
781 | rtx *pnote; | |
e6751e9a | 782 | rtx note; |
13488c51 | 783 | int best_probability = PROB_EVEN; |
b9c74b4d | 784 | enum br_predictor best_predictor = END_PREDICTORS; |
eb429644 | 785 | int combined_probability = REG_BR_PROB_BASE / 2; |
786 | int d; | |
49d7c0db | 787 | bool first_match = false; |
788 | bool found = false; | |
13488c51 | 789 | |
83c8a977 | 790 | if (!can_predict_insn_p (insn)) |
791 | { | |
792 | set_even_probabilities (bb); | |
793 | return; | |
794 | } | |
795 | ||
796 | prob_note = find_reg_note (insn, REG_BR_PROB, 0); | |
797 | pnote = ®_NOTES (insn); | |
450d042a | 798 | if (dump_file) |
799 | fprintf (dump_file, "Predictions for insn %i bb %i\n", INSN_UID (insn), | |
b3d6de89 | 800 | bb->index); |
13488c51 | 801 | |
802 | /* We implement "first match" heuristics and use probability guessed | |
4ee9c684 | 803 | by predictor with smallest index. */ |
e6751e9a | 804 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) |
805 | if (REG_NOTE_KIND (note) == REG_BR_PRED) | |
806 | { | |
bc620c5c | 807 | enum br_predictor predictor = ((enum br_predictor) |
808 | INTVAL (XEXP (XEXP (note, 0), 0))); | |
e6751e9a | 809 | int probability = INTVAL (XEXP (XEXP (note, 0), 1)); |
810 | ||
811 | found = true; | |
812 | if (best_predictor > predictor) | |
813 | best_probability = probability, best_predictor = predictor; | |
814 | ||
815 | d = (combined_probability * probability | |
816 | + (REG_BR_PROB_BASE - combined_probability) | |
817 | * (REG_BR_PROB_BASE - probability)); | |
818 | ||
819 | /* Use FP math to avoid overflows of 32bit integers. */ | |
c4a616f2 | 820 | if (d == 0) |
821 | /* If one probability is 0% and one 100%, avoid division by zero. */ | |
822 | combined_probability = REG_BR_PROB_BASE / 2; | |
823 | else | |
824 | combined_probability = (((double) combined_probability) * probability | |
825 | * REG_BR_PROB_BASE / d + 0.5); | |
e6751e9a | 826 | } |
827 | ||
828 | /* Decide which heuristic to use. In case we didn't match anything, | |
829 | use no_prediction heuristic, in case we did match, use either | |
49d7c0db | 830 | first match or Dempster-Shaffer theory depending on the flags. */ |
831 | ||
eb429644 | 832 | if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH) |
49d7c0db | 833 | first_match = true; |
834 | ||
835 | if (!found) | |
4ee9c684 | 836 | dump_prediction (dump_file, PRED_NO_PREDICTION, |
837 | combined_probability, bb, true); | |
49d7c0db | 838 | else |
839 | { | |
4ee9c684 | 840 | dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, |
841 | bb, !first_match); | |
842 | dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, | |
843 | bb, first_match); | |
49d7c0db | 844 | } |
845 | ||
846 | if (first_match) | |
eb429644 | 847 | combined_probability = best_probability; |
4ee9c684 | 848 | dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); |
49d7c0db | 849 | |
850 | while (*pnote) | |
851 | { | |
852 | if (REG_NOTE_KIND (*pnote) == REG_BR_PRED) | |
853 | { | |
bc620c5c | 854 | enum br_predictor predictor = ((enum br_predictor) |
855 | INTVAL (XEXP (XEXP (*pnote, 0), 0))); | |
49d7c0db | 856 | int probability = INTVAL (XEXP (XEXP (*pnote, 0), 1)); |
857 | ||
4ee9c684 | 858 | dump_prediction (dump_file, predictor, probability, bb, |
49d7c0db | 859 | !first_match || best_predictor == predictor); |
195731ad | 860 | *pnote = XEXP (*pnote, 1); |
49d7c0db | 861 | } |
862 | else | |
195731ad | 863 | pnote = &XEXP (*pnote, 1); |
49d7c0db | 864 | } |
e6751e9a | 865 | |
13488c51 | 866 | if (!prob_note) |
867 | { | |
9eb946de | 868 | add_int_reg_note (insn, REG_BR_PROB, combined_probability); |
e6751e9a | 869 | |
eb429644 | 870 | /* Save the prediction into CFG in case we are seeing non-degenerated |
871 | conditional jump. */ | |
ea091dfd | 872 | if (!single_succ_p (bb)) |
eb429644 | 873 | { |
874 | BRANCH_EDGE (bb)->probability = combined_probability; | |
e6751e9a | 875 | FALLTHRU_EDGE (bb)->probability |
876 | = REG_BR_PROB_BASE - combined_probability; | |
eb429644 | 877 | } |
13488c51 | 878 | } |
ea091dfd | 879 | else if (!single_succ_p (bb)) |
d8c70625 | 880 | { |
9eb946de | 881 | int prob = XINT (prob_note, 0); |
d8c70625 | 882 | |
883 | BRANCH_EDGE (bb)->probability = prob; | |
884 | FALLTHRU_EDGE (bb)->probability = REG_BR_PROB_BASE - prob; | |
885 | } | |
886 | else | |
ea091dfd | 887 | single_succ_edge (bb)->probability = REG_BR_PROB_BASE; |
5e96f51e | 888 | } |
889 | ||
4ee9c684 | 890 | /* Combine predictions into single probability and store them into CFG. |
891 | Remove now useless prediction entries. */ | |
59423b59 | 892 | |
4ee9c684 | 893 | static void |
3f5be5f4 | 894 | combine_predictions_for_bb (basic_block bb) |
59423b59 | 895 | { |
4ee9c684 | 896 | int best_probability = PROB_EVEN; |
b9c74b4d | 897 | enum br_predictor best_predictor = END_PREDICTORS; |
4ee9c684 | 898 | int combined_probability = REG_BR_PROB_BASE / 2; |
899 | int d; | |
900 | bool first_match = false; | |
901 | bool found = false; | |
902 | struct edge_prediction *pred; | |
903 | int nedges = 0; | |
904 | edge e, first = NULL, second = NULL; | |
cd665a06 | 905 | edge_iterator ei; |
b3723726 | 906 | void **preds; |
59423b59 | 907 | |
cd665a06 | 908 | FOR_EACH_EDGE (e, ei, bb->succs) |
4ee9c684 | 909 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
910 | { | |
cd665a06 | 911 | nedges ++; |
4ee9c684 | 912 | if (first && !second) |
913 | second = e; | |
914 | if (!first) | |
915 | first = e; | |
916 | } | |
917 | ||
48e1416a | 918 | /* When there is no successor or only one choice, prediction is easy. |
4ee9c684 | 919 | |
920 | We are lazy for now and predict only basic blocks with two outgoing | |
921 | edges. It is possible to predict generic case too, but we have to | |
922 | ignore first match heuristics and do more involved combining. Implement | |
923 | this later. */ | |
924 | if (nedges != 2) | |
925 | { | |
83c8a977 | 926 | if (!bb->count) |
927 | set_even_probabilities (bb); | |
b3723726 | 928 | clear_bb_predictions (bb); |
3f5be5f4 | 929 | if (dump_file) |
930 | fprintf (dump_file, "%i edges in bb %i predicted to even probabilities\n", | |
4ee9c684 | 931 | nedges, bb->index); |
932 | return; | |
933 | } | |
934 | ||
3f5be5f4 | 935 | if (dump_file) |
936 | fprintf (dump_file, "Predictions for bb %i\n", bb->index); | |
4ee9c684 | 937 | |
b3723726 | 938 | preds = pointer_map_contains (bb_predictions, bb); |
939 | if (preds) | |
4ee9c684 | 940 | { |
b3723726 | 941 | /* We implement "first match" heuristics and use probability guessed |
942 | by predictor with smallest index. */ | |
4077bf7a | 943 | for (pred = (struct edge_prediction *) *preds; pred; pred = pred->ep_next) |
b3723726 | 944 | { |
b9c74b4d | 945 | enum br_predictor predictor = pred->ep_predictor; |
b3723726 | 946 | int probability = pred->ep_probability; |
4ee9c684 | 947 | |
b3723726 | 948 | if (pred->ep_edge != first) |
949 | probability = REG_BR_PROB_BASE - probability; | |
4ee9c684 | 950 | |
b3723726 | 951 | found = true; |
9f694a82 | 952 | /* First match heuristics would be widly confused if we predicted |
953 | both directions. */ | |
b3723726 | 954 | if (best_predictor > predictor) |
9f694a82 | 955 | { |
956 | struct edge_prediction *pred2; | |
957 | int prob = probability; | |
958 | ||
959 | for (pred2 = (struct edge_prediction *) *preds; pred2; pred2 = pred2->ep_next) | |
960 | if (pred2 != pred && pred2->ep_predictor == pred->ep_predictor) | |
961 | { | |
962 | int probability2 = pred->ep_probability; | |
963 | ||
964 | if (pred2->ep_edge != first) | |
965 | probability2 = REG_BR_PROB_BASE - probability2; | |
966 | ||
48e1416a | 967 | if ((probability < REG_BR_PROB_BASE / 2) != |
9f694a82 | 968 | (probability2 < REG_BR_PROB_BASE / 2)) |
969 | break; | |
970 | ||
971 | /* If the same predictor later gave better result, go for it! */ | |
972 | if ((probability >= REG_BR_PROB_BASE / 2 && (probability2 > probability)) | |
973 | || (probability <= REG_BR_PROB_BASE / 2 && (probability2 < probability))) | |
974 | prob = probability2; | |
975 | } | |
976 | if (!pred2) | |
977 | best_probability = prob, best_predictor = predictor; | |
978 | } | |
4ee9c684 | 979 | |
b3723726 | 980 | d = (combined_probability * probability |
981 | + (REG_BR_PROB_BASE - combined_probability) | |
982 | * (REG_BR_PROB_BASE - probability)); | |
4ee9c684 | 983 | |
b3723726 | 984 | /* Use FP math to avoid overflows of 32bit integers. */ |
985 | if (d == 0) | |
986 | /* If one probability is 0% and one 100%, avoid division by zero. */ | |
987 | combined_probability = REG_BR_PROB_BASE / 2; | |
988 | else | |
989 | combined_probability = (((double) combined_probability) | |
990 | * probability | |
991 | * REG_BR_PROB_BASE / d + 0.5); | |
992 | } | |
4ee9c684 | 993 | } |
994 | ||
995 | /* Decide which heuristic to use. In case we didn't match anything, | |
996 | use no_prediction heuristic, in case we did match, use either | |
997 | first match or Dempster-Shaffer theory depending on the flags. */ | |
998 | ||
999 | if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH) | |
1000 | first_match = true; | |
1001 | ||
1002 | if (!found) | |
3f5be5f4 | 1003 | dump_prediction (dump_file, PRED_NO_PREDICTION, combined_probability, bb, true); |
4ee9c684 | 1004 | else |
1005 | { | |
3f5be5f4 | 1006 | dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, bb, |
4ee9c684 | 1007 | !first_match); |
3f5be5f4 | 1008 | dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, bb, |
4ee9c684 | 1009 | first_match); |
1010 | } | |
1011 | ||
1012 | if (first_match) | |
1013 | combined_probability = best_probability; | |
3f5be5f4 | 1014 | dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); |
4ee9c684 | 1015 | |
b3723726 | 1016 | if (preds) |
4ee9c684 | 1017 | { |
4077bf7a | 1018 | for (pred = (struct edge_prediction *) *preds; pred; pred = pred->ep_next) |
b3723726 | 1019 | { |
b9c74b4d | 1020 | enum br_predictor predictor = pred->ep_predictor; |
b3723726 | 1021 | int probability = pred->ep_probability; |
4ee9c684 | 1022 | |
b3723726 | 1023 | if (pred->ep_edge != EDGE_SUCC (bb, 0)) |
1024 | probability = REG_BR_PROB_BASE - probability; | |
1025 | dump_prediction (dump_file, predictor, probability, bb, | |
1026 | !first_match || best_predictor == predictor); | |
1027 | } | |
4ee9c684 | 1028 | } |
b3723726 | 1029 | clear_bb_predictions (bb); |
4ee9c684 | 1030 | |
83c8a977 | 1031 | if (!bb->count) |
1032 | { | |
1033 | first->probability = combined_probability; | |
1034 | second->probability = REG_BR_PROB_BASE - combined_probability; | |
1035 | } | |
4ee9c684 | 1036 | } |
1037 | ||
fd757b76 | 1038 | /* Check if T1 and T2 satisfy the IV_COMPARE condition. |
1039 | Return the SSA_NAME if the condition satisfies, NULL otherwise. | |
1040 | ||
1041 | T1 and T2 should be one of the following cases: | |
1042 | 1. T1 is SSA_NAME, T2 is NULL | |
1043 | 2. T1 is SSA_NAME, T2 is INTEGER_CST between [-4, 4] | |
1044 | 3. T2 is SSA_NAME, T1 is INTEGER_CST between [-4, 4] */ | |
1045 | ||
1046 | static tree | |
1047 | strips_small_constant (tree t1, tree t2) | |
1048 | { | |
1049 | tree ret = NULL; | |
1050 | int value = 0; | |
1051 | ||
1052 | if (!t1) | |
1053 | return NULL; | |
1054 | else if (TREE_CODE (t1) == SSA_NAME) | |
1055 | ret = t1; | |
1056 | else if (host_integerp (t1, 0)) | |
1057 | value = tree_low_cst (t1, 0); | |
1058 | else | |
1059 | return NULL; | |
1060 | ||
1061 | if (!t2) | |
1062 | return ret; | |
1063 | else if (host_integerp (t2, 0)) | |
1064 | value = tree_low_cst (t2, 0); | |
1065 | else if (TREE_CODE (t2) == SSA_NAME) | |
1066 | { | |
1067 | if (ret) | |
1068 | return NULL; | |
1069 | else | |
1070 | ret = t2; | |
1071 | } | |
1072 | ||
1073 | if (value <= 4 && value >= -4) | |
1074 | return ret; | |
1075 | else | |
1076 | return NULL; | |
1077 | } | |
1078 | ||
1079 | /* Return the SSA_NAME in T or T's operands. | |
1080 | Return NULL if SSA_NAME cannot be found. */ | |
1081 | ||
1082 | static tree | |
1083 | get_base_value (tree t) | |
1084 | { | |
1085 | if (TREE_CODE (t) == SSA_NAME) | |
1086 | return t; | |
1087 | ||
1088 | if (!BINARY_CLASS_P (t)) | |
1089 | return NULL; | |
1090 | ||
1091 | switch (TREE_OPERAND_LENGTH (t)) | |
1092 | { | |
1093 | case 1: | |
1094 | return strips_small_constant (TREE_OPERAND (t, 0), NULL); | |
1095 | case 2: | |
1096 | return strips_small_constant (TREE_OPERAND (t, 0), | |
1097 | TREE_OPERAND (t, 1)); | |
1098 | default: | |
1099 | return NULL; | |
1100 | } | |
1101 | } | |
1102 | ||
1103 | /* Check the compare STMT in LOOP. If it compares an induction | |
1104 | variable to a loop invariant, return true, and save | |
1105 | LOOP_INVARIANT, COMPARE_CODE and LOOP_STEP. | |
1106 | Otherwise return false and set LOOP_INVAIANT to NULL. */ | |
1107 | ||
1108 | static bool | |
1109 | is_comparison_with_loop_invariant_p (gimple stmt, struct loop *loop, | |
1110 | tree *loop_invariant, | |
1111 | enum tree_code *compare_code, | |
b3269f54 | 1112 | tree *loop_step, |
fd757b76 | 1113 | tree *loop_iv_base) |
1114 | { | |
1115 | tree op0, op1, bound, base; | |
1116 | affine_iv iv0, iv1; | |
1117 | enum tree_code code; | |
b3269f54 | 1118 | tree step; |
fd757b76 | 1119 | |
1120 | code = gimple_cond_code (stmt); | |
1121 | *loop_invariant = NULL; | |
1122 | ||
1123 | switch (code) | |
1124 | { | |
1125 | case GT_EXPR: | |
1126 | case GE_EXPR: | |
1127 | case NE_EXPR: | |
1128 | case LT_EXPR: | |
1129 | case LE_EXPR: | |
1130 | case EQ_EXPR: | |
1131 | break; | |
1132 | ||
1133 | default: | |
1134 | return false; | |
1135 | } | |
1136 | ||
1137 | op0 = gimple_cond_lhs (stmt); | |
1138 | op1 = gimple_cond_rhs (stmt); | |
1139 | ||
1140 | if ((TREE_CODE (op0) != SSA_NAME && TREE_CODE (op0) != INTEGER_CST) | |
1141 | || (TREE_CODE (op1) != SSA_NAME && TREE_CODE (op1) != INTEGER_CST)) | |
1142 | return false; | |
1143 | if (!simple_iv (loop, loop_containing_stmt (stmt), op0, &iv0, true)) | |
1144 | return false; | |
1145 | if (!simple_iv (loop, loop_containing_stmt (stmt), op1, &iv1, true)) | |
1146 | return false; | |
1147 | if (TREE_CODE (iv0.step) != INTEGER_CST | |
1148 | || TREE_CODE (iv1.step) != INTEGER_CST) | |
1149 | return false; | |
1150 | if ((integer_zerop (iv0.step) && integer_zerop (iv1.step)) | |
1151 | || (!integer_zerop (iv0.step) && !integer_zerop (iv1.step))) | |
1152 | return false; | |
1153 | ||
1154 | if (integer_zerop (iv0.step)) | |
1155 | { | |
1156 | if (code != NE_EXPR && code != EQ_EXPR) | |
1157 | code = invert_tree_comparison (code, false); | |
1158 | bound = iv0.base; | |
1159 | base = iv1.base; | |
1160 | if (host_integerp (iv1.step, 0)) | |
b3269f54 | 1161 | step = iv1.step; |
fd757b76 | 1162 | else |
1163 | return false; | |
1164 | } | |
1165 | else | |
1166 | { | |
1167 | bound = iv1.base; | |
1168 | base = iv0.base; | |
1169 | if (host_integerp (iv0.step, 0)) | |
b3269f54 | 1170 | step = iv0.step; |
fd757b76 | 1171 | else |
1172 | return false; | |
1173 | } | |
1174 | ||
1175 | if (TREE_CODE (bound) != INTEGER_CST) | |
1176 | bound = get_base_value (bound); | |
1177 | if (!bound) | |
1178 | return false; | |
1179 | if (TREE_CODE (base) != INTEGER_CST) | |
1180 | base = get_base_value (base); | |
1181 | if (!base) | |
1182 | return false; | |
1183 | ||
1184 | *loop_invariant = bound; | |
1185 | *compare_code = code; | |
1186 | *loop_step = step; | |
1187 | *loop_iv_base = base; | |
1188 | return true; | |
1189 | } | |
1190 | ||
1191 | /* Compare two SSA_NAMEs: returns TRUE if T1 and T2 are value coherent. */ | |
1192 | ||
1193 | static bool | |
1194 | expr_coherent_p (tree t1, tree t2) | |
1195 | { | |
1196 | gimple stmt; | |
1197 | tree ssa_name_1 = NULL; | |
1198 | tree ssa_name_2 = NULL; | |
1199 | ||
1200 | gcc_assert (TREE_CODE (t1) == SSA_NAME || TREE_CODE (t1) == INTEGER_CST); | |
1201 | gcc_assert (TREE_CODE (t2) == SSA_NAME || TREE_CODE (t2) == INTEGER_CST); | |
1202 | ||
1203 | if (t1 == t2) | |
1204 | return true; | |
1205 | ||
1206 | if (TREE_CODE (t1) == INTEGER_CST && TREE_CODE (t2) == INTEGER_CST) | |
1207 | return true; | |
1208 | if (TREE_CODE (t1) == INTEGER_CST || TREE_CODE (t2) == INTEGER_CST) | |
1209 | return false; | |
1210 | ||
1211 | /* Check to see if t1 is expressed/defined with t2. */ | |
1212 | stmt = SSA_NAME_DEF_STMT (t1); | |
1213 | gcc_assert (stmt != NULL); | |
1214 | if (is_gimple_assign (stmt)) | |
1215 | { | |
1216 | ssa_name_1 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); | |
1217 | if (ssa_name_1 && ssa_name_1 == t2) | |
1218 | return true; | |
1219 | } | |
1220 | ||
1221 | /* Check to see if t2 is expressed/defined with t1. */ | |
1222 | stmt = SSA_NAME_DEF_STMT (t2); | |
1223 | gcc_assert (stmt != NULL); | |
1224 | if (is_gimple_assign (stmt)) | |
1225 | { | |
1226 | ssa_name_2 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); | |
1227 | if (ssa_name_2 && ssa_name_2 == t1) | |
1228 | return true; | |
1229 | } | |
1230 | ||
1231 | /* Compare if t1 and t2's def_stmts are identical. */ | |
1232 | if (ssa_name_2 != NULL && ssa_name_1 == ssa_name_2) | |
1233 | return true; | |
1234 | else | |
1235 | return false; | |
1236 | } | |
1237 | ||
1238 | /* Predict branch probability of BB when BB contains a branch that compares | |
1239 | an induction variable in LOOP with LOOP_IV_BASE_VAR to LOOP_BOUND_VAR. The | |
1240 | loop exit is compared using LOOP_BOUND_CODE, with step of LOOP_BOUND_STEP. | |
1241 | ||
1242 | E.g. | |
1243 | for (int i = 0; i < bound; i++) { | |
1244 | if (i < bound - 2) | |
1245 | computation_1(); | |
1246 | else | |
1247 | computation_2(); | |
1248 | } | |
1249 | ||
1250 | In this loop, we will predict the branch inside the loop to be taken. */ | |
1251 | ||
1252 | static void | |
1253 | predict_iv_comparison (struct loop *loop, basic_block bb, | |
1254 | tree loop_bound_var, | |
1255 | tree loop_iv_base_var, | |
1256 | enum tree_code loop_bound_code, | |
1257 | int loop_bound_step) | |
1258 | { | |
1259 | gimple stmt; | |
1260 | tree compare_var, compare_base; | |
1261 | enum tree_code compare_code; | |
b3269f54 | 1262 | tree compare_step_var; |
fd757b76 | 1263 | edge then_edge; |
1264 | edge_iterator ei; | |
1265 | ||
1266 | if (predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED) | |
1267 | || predicted_by_p (bb, PRED_LOOP_ITERATIONS) | |
1268 | || predicted_by_p (bb, PRED_LOOP_EXIT)) | |
1269 | return; | |
1270 | ||
1271 | stmt = last_stmt (bb); | |
1272 | if (!stmt || gimple_code (stmt) != GIMPLE_COND) | |
1273 | return; | |
1274 | if (!is_comparison_with_loop_invariant_p (stmt, loop, &compare_var, | |
1275 | &compare_code, | |
b3269f54 | 1276 | &compare_step_var, |
fd757b76 | 1277 | &compare_base)) |
1278 | return; | |
1279 | ||
1280 | /* Find the taken edge. */ | |
1281 | FOR_EACH_EDGE (then_edge, ei, bb->succs) | |
1282 | if (then_edge->flags & EDGE_TRUE_VALUE) | |
1283 | break; | |
1284 | ||
1285 | /* When comparing an IV to a loop invariant, NE is more likely to be | |
1286 | taken while EQ is more likely to be not-taken. */ | |
1287 | if (compare_code == NE_EXPR) | |
1288 | { | |
1289 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1290 | return; | |
1291 | } | |
1292 | else if (compare_code == EQ_EXPR) | |
1293 | { | |
1294 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1295 | return; | |
1296 | } | |
1297 | ||
1298 | if (!expr_coherent_p (loop_iv_base_var, compare_base)) | |
1299 | return; | |
1300 | ||
1301 | /* If loop bound, base and compare bound are all constants, we can | |
1302 | calculate the probability directly. */ | |
1303 | if (host_integerp (loop_bound_var, 0) | |
1304 | && host_integerp (compare_var, 0) | |
1305 | && host_integerp (compare_base, 0)) | |
1306 | { | |
1307 | int probability; | |
b3269f54 | 1308 | bool of, overflow = false; |
1309 | double_int mod, compare_count, tem, loop_count; | |
1310 | ||
1311 | double_int loop_bound = tree_to_double_int (loop_bound_var); | |
1312 | double_int compare_bound = tree_to_double_int (compare_var); | |
1313 | double_int base = tree_to_double_int (compare_base); | |
1314 | double_int compare_step = tree_to_double_int (compare_step_var); | |
1315 | ||
1316 | /* (loop_bound - base) / compare_step */ | |
1317 | tem = loop_bound.sub_with_overflow (base, &of); | |
1318 | overflow |= of; | |
1319 | loop_count = tem.divmod_with_overflow (compare_step, | |
1320 | 0, TRUNC_DIV_EXPR, | |
1321 | &mod, &of); | |
1322 | overflow |= of; | |
1323 | ||
1324 | if ((!compare_step.is_negative ()) | |
fd757b76 | 1325 | ^ (compare_code == LT_EXPR || compare_code == LE_EXPR)) |
b3269f54 | 1326 | { |
1327 | /* (loop_bound - compare_bound) / compare_step */ | |
1328 | tem = loop_bound.sub_with_overflow (compare_bound, &of); | |
1329 | overflow |= of; | |
1330 | compare_count = tem.divmod_with_overflow (compare_step, | |
1331 | 0, TRUNC_DIV_EXPR, | |
1332 | &mod, &of); | |
1333 | overflow |= of; | |
1334 | } | |
fd757b76 | 1335 | else |
b3269f54 | 1336 | { |
1337 | /* (compare_bound - base) / compare_step */ | |
1338 | tem = compare_bound.sub_with_overflow (base, &of); | |
1339 | overflow |= of; | |
1340 | compare_count = tem.divmod_with_overflow (compare_step, | |
1341 | 0, TRUNC_DIV_EXPR, | |
1342 | &mod, &of); | |
1343 | overflow |= of; | |
1344 | } | |
fd757b76 | 1345 | if (compare_code == LE_EXPR || compare_code == GE_EXPR) |
b3269f54 | 1346 | ++compare_count; |
fd757b76 | 1347 | if (loop_bound_code == LE_EXPR || loop_bound_code == GE_EXPR) |
b3269f54 | 1348 | ++loop_count; |
1349 | if (compare_count.is_negative ()) | |
1350 | compare_count = double_int_zero; | |
1351 | if (loop_count.is_negative ()) | |
1352 | loop_count = double_int_zero; | |
1353 | if (loop_count.is_zero ()) | |
fd757b76 | 1354 | probability = 0; |
b3269f54 | 1355 | else if (compare_count.scmp (loop_count) == 1) |
fd757b76 | 1356 | probability = REG_BR_PROB_BASE; |
1357 | else | |
b3269f54 | 1358 | { |
1359 | /* If loop_count is too big, such that REG_BR_PROB_BASE * loop_count | |
1360 | could overflow, shift both loop_count and compare_count right | |
1361 | a bit so that it doesn't overflow. Note both counts are known not | |
1362 | to be negative at this point. */ | |
1363 | int clz_bits = clz_hwi (loop_count.high); | |
1364 | gcc_assert (REG_BR_PROB_BASE < 32768); | |
1365 | if (clz_bits < 16) | |
1366 | { | |
1367 | loop_count.arshift (16 - clz_bits, HOST_BITS_PER_DOUBLE_INT); | |
1368 | compare_count.arshift (16 - clz_bits, HOST_BITS_PER_DOUBLE_INT); | |
1369 | } | |
1370 | tem = compare_count.mul_with_sign (double_int::from_shwi | |
1371 | (REG_BR_PROB_BASE), true, &of); | |
1372 | gcc_assert (!of); | |
1373 | tem = tem.divmod (loop_count, true, TRUNC_DIV_EXPR, &mod); | |
1374 | probability = tem.to_uhwi (); | |
1375 | } | |
1376 | ||
1377 | if (!overflow) | |
1378 | predict_edge (then_edge, PRED_LOOP_IV_COMPARE, probability); | |
1379 | ||
fd757b76 | 1380 | return; |
1381 | } | |
1382 | ||
1383 | if (expr_coherent_p (loop_bound_var, compare_var)) | |
1384 | { | |
1385 | if ((loop_bound_code == LT_EXPR || loop_bound_code == LE_EXPR) | |
1386 | && (compare_code == LT_EXPR || compare_code == LE_EXPR)) | |
1387 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1388 | else if ((loop_bound_code == GT_EXPR || loop_bound_code == GE_EXPR) | |
1389 | && (compare_code == GT_EXPR || compare_code == GE_EXPR)) | |
1390 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1391 | else if (loop_bound_code == NE_EXPR) | |
1392 | { | |
1393 | /* If the loop backedge condition is "(i != bound)", we do | |
1394 | the comparison based on the step of IV: | |
1395 | * step < 0 : backedge condition is like (i > bound) | |
1396 | * step > 0 : backedge condition is like (i < bound) */ | |
1397 | gcc_assert (loop_bound_step != 0); | |
1398 | if (loop_bound_step > 0 | |
1399 | && (compare_code == LT_EXPR | |
1400 | || compare_code == LE_EXPR)) | |
1401 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1402 | else if (loop_bound_step < 0 | |
1403 | && (compare_code == GT_EXPR | |
1404 | || compare_code == GE_EXPR)) | |
1405 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1406 | else | |
1407 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1408 | } | |
1409 | else | |
1410 | /* The branch is predicted not-taken if loop_bound_code is | |
1411 | opposite with compare_code. */ | |
1412 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1413 | } | |
1414 | else if (expr_coherent_p (loop_iv_base_var, compare_var)) | |
1415 | { | |
1416 | /* For cases like: | |
1417 | for (i = s; i < h; i++) | |
1418 | if (i > s + 2) .... | |
1419 | The branch should be predicted taken. */ | |
1420 | if (loop_bound_step > 0 | |
1421 | && (compare_code == GT_EXPR || compare_code == GE_EXPR)) | |
1422 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1423 | else if (loop_bound_step < 0 | |
1424 | && (compare_code == LT_EXPR || compare_code == LE_EXPR)) | |
1425 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1426 | else | |
1427 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1428 | } | |
1429 | } | |
4ca17abf | 1430 | |
1431 | /* Predict for extra loop exits that will lead to EXIT_EDGE. The extra loop | |
1432 | exits are resulted from short-circuit conditions that will generate an | |
1433 | if_tmp. E.g.: | |
1434 | ||
1435 | if (foo() || global > 10) | |
1436 | break; | |
1437 | ||
1438 | This will be translated into: | |
1439 | ||
1440 | BB3: | |
1441 | loop header... | |
1442 | BB4: | |
1443 | if foo() goto BB6 else goto BB5 | |
1444 | BB5: | |
1445 | if global > 10 goto BB6 else goto BB7 | |
1446 | BB6: | |
1447 | goto BB7 | |
1448 | BB7: | |
1449 | iftmp = (PHI 0(BB5), 1(BB6)) | |
1450 | if iftmp == 1 goto BB8 else goto BB3 | |
1451 | BB8: | |
1452 | outside of the loop... | |
1453 | ||
1454 | The edge BB7->BB8 is loop exit because BB8 is outside of the loop. | |
1455 | From the dataflow, we can infer that BB4->BB6 and BB5->BB6 are also loop | |
1456 | exits. This function takes BB7->BB8 as input, and finds out the extra loop | |
1457 | exits to predict them using PRED_LOOP_EXIT. */ | |
1458 | ||
1459 | static void | |
1460 | predict_extra_loop_exits (edge exit_edge) | |
1461 | { | |
1462 | unsigned i; | |
1463 | bool check_value_one; | |
1464 | gimple phi_stmt; | |
1465 | tree cmp_rhs, cmp_lhs; | |
1466 | gimple cmp_stmt = last_stmt (exit_edge->src); | |
1467 | ||
1468 | if (!cmp_stmt || gimple_code (cmp_stmt) != GIMPLE_COND) | |
1469 | return; | |
1470 | cmp_rhs = gimple_cond_rhs (cmp_stmt); | |
1471 | cmp_lhs = gimple_cond_lhs (cmp_stmt); | |
1472 | if (!TREE_CONSTANT (cmp_rhs) | |
1473 | || !(integer_zerop (cmp_rhs) || integer_onep (cmp_rhs))) | |
1474 | return; | |
1475 | if (TREE_CODE (cmp_lhs) != SSA_NAME) | |
1476 | return; | |
1477 | ||
1478 | /* If check_value_one is true, only the phi_args with value '1' will lead | |
1479 | to loop exit. Otherwise, only the phi_args with value '0' will lead to | |
1480 | loop exit. */ | |
1481 | check_value_one = (((integer_onep (cmp_rhs)) | |
1482 | ^ (gimple_cond_code (cmp_stmt) == EQ_EXPR)) | |
1483 | ^ ((exit_edge->flags & EDGE_TRUE_VALUE) != 0)); | |
1484 | ||
1485 | phi_stmt = SSA_NAME_DEF_STMT (cmp_lhs); | |
1486 | if (!phi_stmt || gimple_code (phi_stmt) != GIMPLE_PHI) | |
1487 | return; | |
1488 | ||
1489 | for (i = 0; i < gimple_phi_num_args (phi_stmt); i++) | |
1490 | { | |
1491 | edge e1; | |
1492 | edge_iterator ei; | |
1493 | tree val = gimple_phi_arg_def (phi_stmt, i); | |
1494 | edge e = gimple_phi_arg_edge (phi_stmt, i); | |
1495 | ||
1496 | if (!TREE_CONSTANT (val) || !(integer_zerop (val) || integer_onep (val))) | |
1497 | continue; | |
1498 | if ((check_value_one ^ integer_onep (val)) == 1) | |
1499 | continue; | |
1500 | if (EDGE_COUNT (e->src->succs) != 1) | |
1501 | { | |
1502 | predict_paths_leading_to_edge (e, PRED_LOOP_EXIT, NOT_TAKEN); | |
1503 | continue; | |
1504 | } | |
1505 | ||
1506 | FOR_EACH_EDGE (e1, ei, e->src->preds) | |
1507 | predict_paths_leading_to_edge (e1, PRED_LOOP_EXIT, NOT_TAKEN); | |
1508 | } | |
1509 | } | |
1510 | ||
7194de72 | 1511 | /* Predict edge probabilities by exploiting loop structure. */ |
1512 | ||
4ee9c684 | 1513 | static void |
7194de72 | 1514 | predict_loops (void) |
4ee9c684 | 1515 | { |
17519ba0 | 1516 | loop_iterator li; |
1517 | struct loop *loop; | |
c12f2fcb | 1518 | |
7fcadf62 | 1519 | /* Try to predict out blocks in a loop that are not part of a |
1520 | natural loop. */ | |
17519ba0 | 1521 | FOR_EACH_LOOP (li, loop, 0) |
59423b59 | 1522 | { |
7fb12188 | 1523 | basic_block bb, *bbs; |
749ea85f | 1524 | unsigned j, n_exits; |
f1f41a6c | 1525 | vec<edge> exits; |
3b0b2309 | 1526 | struct tree_niter_desc niter_desc; |
749ea85f | 1527 | edge ex; |
fd757b76 | 1528 | struct nb_iter_bound *nb_iter; |
1529 | enum tree_code loop_bound_code = ERROR_MARK; | |
b3269f54 | 1530 | tree loop_bound_step = NULL; |
fd757b76 | 1531 | tree loop_bound_var = NULL; |
1532 | tree loop_iv_base = NULL; | |
1533 | gimple stmt = NULL; | |
59423b59 | 1534 | |
749ea85f | 1535 | exits = get_loop_exit_edges (loop); |
f1f41a6c | 1536 | n_exits = exits.length (); |
5d865361 | 1537 | if (!n_exits) |
1538 | { | |
f1f41a6c | 1539 | exits.release (); |
5d865361 | 1540 | continue; |
1541 | } | |
ba38e12b | 1542 | |
f1f41a6c | 1543 | FOR_EACH_VEC_ELT (exits, j, ex) |
d27b0b64 | 1544 | { |
3b0b2309 | 1545 | tree niter = NULL; |
d500fef3 | 1546 | HOST_WIDE_INT nitercst; |
1547 | int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS); | |
1548 | int probability; | |
1549 | enum br_predictor predictor; | |
d27b0b64 | 1550 | |
4ca17abf | 1551 | predict_extra_loop_exits (ex); |
1552 | ||
3f78e715 | 1553 | if (number_of_iterations_exit (loop, ex, &niter_desc, false, false)) |
3b0b2309 | 1554 | niter = niter_desc.niter; |
1555 | if (!niter || TREE_CODE (niter_desc.niter) != INTEGER_CST) | |
749ea85f | 1556 | niter = loop_niter_by_eval (loop, ex); |
d27b0b64 | 1557 | |
3b0b2309 | 1558 | if (TREE_CODE (niter) == INTEGER_CST) |
1559 | { | |
3b0b2309 | 1560 | if (host_integerp (niter, 1) |
ed60f27f | 1561 | && max |
1562 | && compare_tree_int (niter, max - 1) == -1) | |
d500fef3 | 1563 | nitercst = tree_low_cst (niter, 1) + 1; |
3b0b2309 | 1564 | else |
d500fef3 | 1565 | nitercst = max; |
1566 | predictor = PRED_LOOP_ITERATIONS; | |
1567 | } | |
1568 | /* If we have just one exit and we can derive some information about | |
1569 | the number of iterations of the loop from the statements inside | |
1570 | the loop, use it to predict this exit. */ | |
1571 | else if (n_exits == 1) | |
1572 | { | |
fee017b3 | 1573 | nitercst = estimated_stmt_executions_int (loop); |
d500fef3 | 1574 | if (nitercst < 0) |
1575 | continue; | |
1576 | if (nitercst > max) | |
1577 | nitercst = max; | |
d27b0b64 | 1578 | |
d500fef3 | 1579 | predictor = PRED_LOOP_ITERATIONS_GUESSED; |
3b0b2309 | 1580 | } |
d500fef3 | 1581 | else |
1582 | continue; | |
1583 | ||
ed60f27f | 1584 | /* If the prediction for number of iterations is zero, do not |
1585 | predict the exit edges. */ | |
1586 | if (nitercst == 0) | |
1587 | continue; | |
1588 | ||
d500fef3 | 1589 | probability = ((REG_BR_PROB_BASE + nitercst / 2) / nitercst); |
1590 | predict_edge (ex, predictor, probability); | |
d27b0b64 | 1591 | } |
f1f41a6c | 1592 | exits.release (); |
862be747 | 1593 | |
fd757b76 | 1594 | /* Find information about loop bound variables. */ |
1595 | for (nb_iter = loop->bounds; nb_iter; | |
1596 | nb_iter = nb_iter->next) | |
1597 | if (nb_iter->stmt | |
1598 | && gimple_code (nb_iter->stmt) == GIMPLE_COND) | |
1599 | { | |
1600 | stmt = nb_iter->stmt; | |
1601 | break; | |
1602 | } | |
1603 | if (!stmt && last_stmt (loop->header) | |
1604 | && gimple_code (last_stmt (loop->header)) == GIMPLE_COND) | |
1605 | stmt = last_stmt (loop->header); | |
1606 | if (stmt) | |
1607 | is_comparison_with_loop_invariant_p (stmt, loop, | |
1608 | &loop_bound_var, | |
1609 | &loop_bound_code, | |
1610 | &loop_bound_step, | |
1611 | &loop_iv_base); | |
1612 | ||
7fb12188 | 1613 | bbs = get_loop_body (loop); |
4ee9c684 | 1614 | |
7fb12188 | 1615 | for (j = 0; j < loop->num_nodes; j++) |
1616 | { | |
1617 | int header_found = 0; | |
1618 | edge e; | |
cd665a06 | 1619 | edge_iterator ei; |
7fb12188 | 1620 | |
1621 | bb = bbs[j]; | |
e6751e9a | 1622 | |
cd0fe062 | 1623 | /* Bypass loop heuristics on continue statement. These |
1624 | statements construct loops via "non-loop" constructs | |
1625 | in the source language and are better to be handled | |
1626 | separately. */ | |
3b0b2309 | 1627 | if (predicted_by_p (bb, PRED_CONTINUE)) |
cd0fe062 | 1628 | continue; |
1629 | ||
7fb12188 | 1630 | /* Loop branch heuristics - predict an edge back to a |
1631 | loop's head as taken. */ | |
c6356c17 | 1632 | if (bb == loop->latch) |
1633 | { | |
1634 | e = find_edge (loop->latch, loop->header); | |
1635 | if (e) | |
1636 | { | |
1637 | header_found = 1; | |
1638 | predict_edge_def (e, PRED_LOOP_BRANCH, TAKEN); | |
1639 | } | |
1640 | } | |
e6751e9a | 1641 | |
7fb12188 | 1642 | /* Loop exit heuristics - predict an edge exiting the loop if the |
41a6f238 | 1643 | conditional has no loop header successors as not taken. */ |
d500fef3 | 1644 | if (!header_found |
1645 | /* If we already used more reliable loop exit predictors, do not | |
1646 | bother with PRED_LOOP_EXIT. */ | |
1647 | && !predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED) | |
1648 | && !predicted_by_p (bb, PRED_LOOP_ITERATIONS)) | |
b41438e5 | 1649 | { |
1650 | /* For loop with many exits we don't want to predict all exits | |
1651 | with the pretty large probability, because if all exits are | |
1652 | considered in row, the loop would be predicted to iterate | |
1653 | almost never. The code to divide probability by number of | |
1654 | exits is very rough. It should compute the number of exits | |
1655 | taken in each patch through function (not the overall number | |
1656 | of exits that might be a lot higher for loops with wide switch | |
1657 | statements in them) and compute n-th square root. | |
1658 | ||
1659 | We limit the minimal probability by 2% to avoid | |
1660 | EDGE_PROBABILITY_RELIABLE from trusting the branch prediction | |
1661 | as this was causing regression in perl benchmark containing such | |
1662 | a wide loop. */ | |
48e1416a | 1663 | |
b41438e5 | 1664 | int probability = ((REG_BR_PROB_BASE |
1665 | - predictor_info [(int) PRED_LOOP_EXIT].hitrate) | |
1666 | / n_exits); | |
1667 | if (probability < HITRATE (2)) | |
1668 | probability = HITRATE (2); | |
1669 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1670 | if (e->dest->index < NUM_FIXED_BLOCKS | |
1671 | || !flow_bb_inside_loop_p (loop, e->dest)) | |
1672 | predict_edge (e, PRED_LOOP_EXIT, probability); | |
1673 | } | |
fd757b76 | 1674 | if (loop_bound_var) |
1675 | predict_iv_comparison (loop, bb, loop_bound_var, loop_iv_base, | |
1676 | loop_bound_code, | |
b3269f54 | 1677 | tree_low_cst (loop_bound_step, 0)); |
7fb12188 | 1678 | } |
48e1416a | 1679 | |
21dda4ee | 1680 | /* Free basic blocks from get_loop_body. */ |
dcd8fd01 | 1681 | free (bbs); |
59423b59 | 1682 | } |
4ee9c684 | 1683 | } |
1684 | ||
83c8a977 | 1685 | /* Attempt to predict probabilities of BB outgoing edges using local |
1686 | properties. */ | |
1687 | static void | |
1688 | bb_estimate_probability_locally (basic_block bb) | |
1689 | { | |
1690 | rtx last_insn = BB_END (bb); | |
1691 | rtx cond; | |
1692 | ||
1693 | if (! can_predict_insn_p (last_insn)) | |
1694 | return; | |
1695 | cond = get_condition (last_insn, NULL, false, false); | |
1696 | if (! cond) | |
1697 | return; | |
1698 | ||
1699 | /* Try "pointer heuristic." | |
1700 | A comparison ptr == 0 is predicted as false. | |
1701 | Similarly, a comparison ptr1 == ptr2 is predicted as false. */ | |
1702 | if (COMPARISON_P (cond) | |
1703 | && ((REG_P (XEXP (cond, 0)) && REG_POINTER (XEXP (cond, 0))) | |
1704 | || (REG_P (XEXP (cond, 1)) && REG_POINTER (XEXP (cond, 1))))) | |
1705 | { | |
1706 | if (GET_CODE (cond) == EQ) | |
1707 | predict_insn_def (last_insn, PRED_POINTER, NOT_TAKEN); | |
1708 | else if (GET_CODE (cond) == NE) | |
1709 | predict_insn_def (last_insn, PRED_POINTER, TAKEN); | |
1710 | } | |
1711 | else | |
1712 | ||
1713 | /* Try "opcode heuristic." | |
1714 | EQ tests are usually false and NE tests are usually true. Also, | |
1715 | most quantities are positive, so we can make the appropriate guesses | |
1716 | about signed comparisons against zero. */ | |
1717 | switch (GET_CODE (cond)) | |
1718 | { | |
1719 | case CONST_INT: | |
1720 | /* Unconditional branch. */ | |
1721 | predict_insn_def (last_insn, PRED_UNCONDITIONAL, | |
1722 | cond == const0_rtx ? NOT_TAKEN : TAKEN); | |
1723 | break; | |
1724 | ||
1725 | case EQ: | |
1726 | case UNEQ: | |
1727 | /* Floating point comparisons appears to behave in a very | |
1728 | unpredictable way because of special role of = tests in | |
1729 | FP code. */ | |
1730 | if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0)))) | |
1731 | ; | |
1732 | /* Comparisons with 0 are often used for booleans and there is | |
1733 | nothing useful to predict about them. */ | |
1734 | else if (XEXP (cond, 1) == const0_rtx | |
1735 | || XEXP (cond, 0) == const0_rtx) | |
1736 | ; | |
1737 | else | |
1738 | predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, NOT_TAKEN); | |
1739 | break; | |
1740 | ||
1741 | case NE: | |
1742 | case LTGT: | |
1743 | /* Floating point comparisons appears to behave in a very | |
1744 | unpredictable way because of special role of = tests in | |
1745 | FP code. */ | |
1746 | if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0)))) | |
1747 | ; | |
1748 | /* Comparisons with 0 are often used for booleans and there is | |
1749 | nothing useful to predict about them. */ | |
1750 | else if (XEXP (cond, 1) == const0_rtx | |
1751 | || XEXP (cond, 0) == const0_rtx) | |
1752 | ; | |
1753 | else | |
1754 | predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, TAKEN); | |
1755 | break; | |
1756 | ||
1757 | case ORDERED: | |
1758 | predict_insn_def (last_insn, PRED_FPOPCODE, TAKEN); | |
1759 | break; | |
1760 | ||
1761 | case UNORDERED: | |
1762 | predict_insn_def (last_insn, PRED_FPOPCODE, NOT_TAKEN); | |
1763 | break; | |
1764 | ||
1765 | case LE: | |
1766 | case LT: | |
1767 | if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx | |
1768 | || XEXP (cond, 1) == constm1_rtx) | |
1769 | predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, NOT_TAKEN); | |
1770 | break; | |
1771 | ||
1772 | case GE: | |
1773 | case GT: | |
1774 | if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx | |
1775 | || XEXP (cond, 1) == constm1_rtx) | |
1776 | predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, TAKEN); | |
1777 | break; | |
1778 | ||
1779 | default: | |
1780 | break; | |
1781 | } | |
1782 | } | |
1783 | ||
7edd21a5 | 1784 | /* Set edge->probability for each successor edge of BB. */ |
83c8a977 | 1785 | void |
1786 | guess_outgoing_edge_probabilities (basic_block bb) | |
1787 | { | |
1788 | bb_estimate_probability_locally (bb); | |
1789 | combine_predictions_for_insn (BB_END (bb), bb); | |
1790 | } | |
4ee9c684 | 1791 | \f |
75a70cf9 | 1792 | static tree expr_expected_value (tree, bitmap); |
1793 | ||
1794 | /* Helper function for expr_expected_value. */ | |
42975b1f | 1795 | |
1796 | static tree | |
2380e91e | 1797 | expr_expected_value_1 (tree type, tree op0, enum tree_code code, |
1798 | tree op1, bitmap visited) | |
42975b1f | 1799 | { |
75a70cf9 | 1800 | gimple def; |
1801 | ||
1802 | if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS) | |
42975b1f | 1803 | { |
75a70cf9 | 1804 | if (TREE_CONSTANT (op0)) |
1805 | return op0; | |
1806 | ||
1807 | if (code != SSA_NAME) | |
1808 | return NULL_TREE; | |
1809 | ||
1810 | def = SSA_NAME_DEF_STMT (op0); | |
42975b1f | 1811 | |
1812 | /* If we were already here, break the infinite cycle. */ | |
6ef9bbe0 | 1813 | if (!bitmap_set_bit (visited, SSA_NAME_VERSION (op0))) |
42975b1f | 1814 | return NULL; |
42975b1f | 1815 | |
75a70cf9 | 1816 | if (gimple_code (def) == GIMPLE_PHI) |
42975b1f | 1817 | { |
1818 | /* All the arguments of the PHI node must have the same constant | |
1819 | length. */ | |
75a70cf9 | 1820 | int i, n = gimple_phi_num_args (def); |
42975b1f | 1821 | tree val = NULL, new_val; |
4ee9c684 | 1822 | |
75a70cf9 | 1823 | for (i = 0; i < n; i++) |
42975b1f | 1824 | { |
1825 | tree arg = PHI_ARG_DEF (def, i); | |
1826 | ||
1827 | /* If this PHI has itself as an argument, we cannot | |
1828 | determine the string length of this argument. However, | |
86481e89 | 1829 | if we can find an expected constant value for the other |
42975b1f | 1830 | PHI args then we can still be sure that this is |
1831 | likely a constant. So be optimistic and just | |
1832 | continue with the next argument. */ | |
1833 | if (arg == PHI_RESULT (def)) | |
1834 | continue; | |
1835 | ||
1836 | new_val = expr_expected_value (arg, visited); | |
1837 | if (!new_val) | |
1838 | return NULL; | |
1839 | if (!val) | |
1840 | val = new_val; | |
1841 | else if (!operand_equal_p (val, new_val, false)) | |
1842 | return NULL; | |
1843 | } | |
1844 | return val; | |
1845 | } | |
75a70cf9 | 1846 | if (is_gimple_assign (def)) |
42975b1f | 1847 | { |
75a70cf9 | 1848 | if (gimple_assign_lhs (def) != op0) |
1849 | return NULL; | |
42975b1f | 1850 | |
75a70cf9 | 1851 | return expr_expected_value_1 (TREE_TYPE (gimple_assign_lhs (def)), |
1852 | gimple_assign_rhs1 (def), | |
1853 | gimple_assign_rhs_code (def), | |
1854 | gimple_assign_rhs2 (def), | |
1855 | visited); | |
1856 | } | |
1857 | ||
1858 | if (is_gimple_call (def)) | |
1859 | { | |
1860 | tree decl = gimple_call_fndecl (def); | |
1861 | if (!decl) | |
c2f47e15 | 1862 | return NULL; |
2380e91e | 1863 | if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL) |
1864 | switch (DECL_FUNCTION_CODE (decl)) | |
1865 | { | |
1866 | case BUILT_IN_EXPECT: | |
1867 | { | |
1868 | tree val; | |
1869 | if (gimple_call_num_args (def) != 2) | |
1870 | return NULL; | |
1871 | val = gimple_call_arg (def, 0); | |
1872 | if (TREE_CONSTANT (val)) | |
1873 | return val; | |
1874 | return gimple_call_arg (def, 1); | |
1875 | } | |
75a70cf9 | 1876 | |
2380e91e | 1877 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_N: |
1878 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_1: | |
1879 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2: | |
1880 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4: | |
1881 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8: | |
1882 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16: | |
1883 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE: | |
1884 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_N: | |
1885 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1: | |
1886 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2: | |
1887 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4: | |
1888 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8: | |
1889 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16: | |
1890 | /* Assume that any given atomic operation has low contention, | |
1891 | and thus the compare-and-swap operation succeeds. */ | |
1892 | return boolean_true_node; | |
75a70cf9 | 1893 | } |
42975b1f | 1894 | } |
75a70cf9 | 1895 | |
1896 | return NULL; | |
42975b1f | 1897 | } |
75a70cf9 | 1898 | |
1899 | if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS) | |
42975b1f | 1900 | { |
75a70cf9 | 1901 | tree res; |
1902 | op0 = expr_expected_value (op0, visited); | |
42975b1f | 1903 | if (!op0) |
1904 | return NULL; | |
75a70cf9 | 1905 | op1 = expr_expected_value (op1, visited); |
42975b1f | 1906 | if (!op1) |
1907 | return NULL; | |
75a70cf9 | 1908 | res = fold_build2 (code, type, op0, op1); |
42975b1f | 1909 | if (TREE_CONSTANT (res)) |
1910 | return res; | |
1911 | return NULL; | |
1912 | } | |
75a70cf9 | 1913 | if (get_gimple_rhs_class (code) == GIMPLE_UNARY_RHS) |
42975b1f | 1914 | { |
75a70cf9 | 1915 | tree res; |
1916 | op0 = expr_expected_value (op0, visited); | |
42975b1f | 1917 | if (!op0) |
1918 | return NULL; | |
75a70cf9 | 1919 | res = fold_build1 (code, type, op0); |
42975b1f | 1920 | if (TREE_CONSTANT (res)) |
1921 | return res; | |
1922 | return NULL; | |
1923 | } | |
1924 | return NULL; | |
1925 | } | |
75a70cf9 | 1926 | |
48e1416a | 1927 | /* Return constant EXPR will likely have at execution time, NULL if unknown. |
75a70cf9 | 1928 | The function is used by builtin_expect branch predictor so the evidence |
1929 | must come from this construct and additional possible constant folding. | |
48e1416a | 1930 | |
75a70cf9 | 1931 | We may want to implement more involved value guess (such as value range |
1932 | propagation based prediction), but such tricks shall go to new | |
1933 | implementation. */ | |
1934 | ||
1935 | static tree | |
1936 | expr_expected_value (tree expr, bitmap visited) | |
1937 | { | |
1938 | enum tree_code code; | |
1939 | tree op0, op1; | |
1940 | ||
1941 | if (TREE_CONSTANT (expr)) | |
1942 | return expr; | |
1943 | ||
1944 | extract_ops_from_tree (expr, &code, &op0, &op1); | |
1945 | return expr_expected_value_1 (TREE_TYPE (expr), | |
1946 | op0, code, op1, visited); | |
1947 | } | |
1948 | ||
42975b1f | 1949 | \f |
1add270f | 1950 | /* Get rid of all builtin_expect calls and GIMPLE_PREDICT statements |
1951 | we no longer need. */ | |
1952 | static unsigned int | |
1953 | strip_predict_hints (void) | |
42975b1f | 1954 | { |
1955 | basic_block bb; | |
75a70cf9 | 1956 | gimple ass_stmt; |
1957 | tree var; | |
1958 | ||
42975b1f | 1959 | FOR_EACH_BB (bb) |
1960 | { | |
75a70cf9 | 1961 | gimple_stmt_iterator bi; |
1add270f | 1962 | for (bi = gsi_start_bb (bb); !gsi_end_p (bi);) |
42975b1f | 1963 | { |
75a70cf9 | 1964 | gimple stmt = gsi_stmt (bi); |
75a70cf9 | 1965 | |
1add270f | 1966 | if (gimple_code (stmt) == GIMPLE_PREDICT) |
1967 | { | |
1968 | gsi_remove (&bi, true); | |
1969 | continue; | |
1970 | } | |
1971 | else if (gimple_code (stmt) == GIMPLE_CALL) | |
42975b1f | 1972 | { |
1add270f | 1973 | tree fndecl = gimple_call_fndecl (stmt); |
75a70cf9 | 1974 | |
1add270f | 1975 | if (fndecl |
1976 | && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL | |
1977 | && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT | |
1978 | && gimple_call_num_args (stmt) == 2) | |
1979 | { | |
1980 | var = gimple_call_lhs (stmt); | |
056af318 | 1981 | if (var) |
1982 | { | |
1983 | ass_stmt | |
1984 | = gimple_build_assign (var, gimple_call_arg (stmt, 0)); | |
1985 | gsi_replace (&bi, ass_stmt, true); | |
1986 | } | |
1987 | else | |
1988 | { | |
1989 | gsi_remove (&bi, true); | |
1990 | continue; | |
1991 | } | |
1add270f | 1992 | } |
42975b1f | 1993 | } |
1add270f | 1994 | gsi_next (&bi); |
42975b1f | 1995 | } |
1996 | } | |
1add270f | 1997 | return 0; |
42975b1f | 1998 | } |
1999 | \f | |
4ee9c684 | 2000 | /* Predict using opcode of the last statement in basic block. */ |
2001 | static void | |
2002 | tree_predict_by_opcode (basic_block bb) | |
2003 | { | |
75a70cf9 | 2004 | gimple stmt = last_stmt (bb); |
4ee9c684 | 2005 | edge then_edge; |
75a70cf9 | 2006 | tree op0, op1; |
4ee9c684 | 2007 | tree type; |
42975b1f | 2008 | tree val; |
75a70cf9 | 2009 | enum tree_code cmp; |
42975b1f | 2010 | bitmap visited; |
cd665a06 | 2011 | edge_iterator ei; |
4ee9c684 | 2012 | |
75a70cf9 | 2013 | if (!stmt || gimple_code (stmt) != GIMPLE_COND) |
4ee9c684 | 2014 | return; |
cd665a06 | 2015 | FOR_EACH_EDGE (then_edge, ei, bb->succs) |
4ee9c684 | 2016 | if (then_edge->flags & EDGE_TRUE_VALUE) |
cd665a06 | 2017 | break; |
75a70cf9 | 2018 | op0 = gimple_cond_lhs (stmt); |
2019 | op1 = gimple_cond_rhs (stmt); | |
2020 | cmp = gimple_cond_code (stmt); | |
4ee9c684 | 2021 | type = TREE_TYPE (op0); |
27335ffd | 2022 | visited = BITMAP_ALLOC (NULL); |
75a70cf9 | 2023 | val = expr_expected_value_1 (boolean_type_node, op0, cmp, op1, visited); |
27335ffd | 2024 | BITMAP_FREE (visited); |
42975b1f | 2025 | if (val) |
2026 | { | |
21853731 | 2027 | int percent = PARAM_VALUE (BUILTIN_EXPECT_PROBABILITY); |
2028 | ||
2029 | gcc_assert (percent >= 0 && percent <= 100); | |
42975b1f | 2030 | if (integer_zerop (val)) |
21853731 | 2031 | percent = 100 - percent; |
2032 | predict_edge (then_edge, PRED_BUILTIN_EXPECT, HITRATE (percent)); | |
42975b1f | 2033 | } |
4ee9c684 | 2034 | /* Try "pointer heuristic." |
2035 | A comparison ptr == 0 is predicted as false. | |
2036 | Similarly, a comparison ptr1 == ptr2 is predicted as false. */ | |
2037 | if (POINTER_TYPE_P (type)) | |
2038 | { | |
75a70cf9 | 2039 | if (cmp == EQ_EXPR) |
4ee9c684 | 2040 | predict_edge_def (then_edge, PRED_TREE_POINTER, NOT_TAKEN); |
75a70cf9 | 2041 | else if (cmp == NE_EXPR) |
4ee9c684 | 2042 | predict_edge_def (then_edge, PRED_TREE_POINTER, TAKEN); |
2043 | } | |
2044 | else | |
2045 | ||
2046 | /* Try "opcode heuristic." | |
2047 | EQ tests are usually false and NE tests are usually true. Also, | |
2048 | most quantities are positive, so we can make the appropriate guesses | |
2049 | about signed comparisons against zero. */ | |
75a70cf9 | 2050 | switch (cmp) |
4ee9c684 | 2051 | { |
2052 | case EQ_EXPR: | |
2053 | case UNEQ_EXPR: | |
2054 | /* Floating point comparisons appears to behave in a very | |
2055 | unpredictable way because of special role of = tests in | |
2056 | FP code. */ | |
2057 | if (FLOAT_TYPE_P (type)) | |
2058 | ; | |
2059 | /* Comparisons with 0 are often used for booleans and there is | |
2060 | nothing useful to predict about them. */ | |
75a70cf9 | 2061 | else if (integer_zerop (op0) || integer_zerop (op1)) |
4ee9c684 | 2062 | ; |
2063 | else | |
2064 | predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, NOT_TAKEN); | |
2065 | break; | |
2066 | ||
2067 | case NE_EXPR: | |
318a728f | 2068 | case LTGT_EXPR: |
4ee9c684 | 2069 | /* Floating point comparisons appears to behave in a very |
2070 | unpredictable way because of special role of = tests in | |
2071 | FP code. */ | |
2072 | if (FLOAT_TYPE_P (type)) | |
2073 | ; | |
2074 | /* Comparisons with 0 are often used for booleans and there is | |
2075 | nothing useful to predict about them. */ | |
2076 | else if (integer_zerop (op0) | |
75a70cf9 | 2077 | || integer_zerop (op1)) |
4ee9c684 | 2078 | ; |
2079 | else | |
2080 | predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, TAKEN); | |
2081 | break; | |
2082 | ||
2083 | case ORDERED_EXPR: | |
2084 | predict_edge_def (then_edge, PRED_TREE_FPOPCODE, TAKEN); | |
2085 | break; | |
2086 | ||
2087 | case UNORDERED_EXPR: | |
2088 | predict_edge_def (then_edge, PRED_TREE_FPOPCODE, NOT_TAKEN); | |
2089 | break; | |
2090 | ||
2091 | case LE_EXPR: | |
2092 | case LT_EXPR: | |
75a70cf9 | 2093 | if (integer_zerop (op1) |
2094 | || integer_onep (op1) | |
2095 | || integer_all_onesp (op1) | |
2096 | || real_zerop (op1) | |
2097 | || real_onep (op1) | |
2098 | || real_minus_onep (op1)) | |
4ee9c684 | 2099 | predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, NOT_TAKEN); |
2100 | break; | |
2101 | ||
2102 | case GE_EXPR: | |
2103 | case GT_EXPR: | |
75a70cf9 | 2104 | if (integer_zerop (op1) |
2105 | || integer_onep (op1) | |
2106 | || integer_all_onesp (op1) | |
2107 | || real_zerop (op1) | |
2108 | || real_onep (op1) | |
2109 | || real_minus_onep (op1)) | |
4ee9c684 | 2110 | predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, TAKEN); |
2111 | break; | |
2112 | ||
2113 | default: | |
2114 | break; | |
2115 | } | |
2116 | } | |
2117 | ||
f816ec49 | 2118 | /* Try to guess whether the value of return means error code. */ |
75a70cf9 | 2119 | |
f816ec49 | 2120 | static enum br_predictor |
2121 | return_prediction (tree val, enum prediction *prediction) | |
2122 | { | |
2123 | /* VOID. */ | |
2124 | if (!val) | |
2125 | return PRED_NO_PREDICTION; | |
2126 | /* Different heuristics for pointers and scalars. */ | |
2127 | if (POINTER_TYPE_P (TREE_TYPE (val))) | |
2128 | { | |
2129 | /* NULL is usually not returned. */ | |
2130 | if (integer_zerop (val)) | |
2131 | { | |
2132 | *prediction = NOT_TAKEN; | |
2133 | return PRED_NULL_RETURN; | |
2134 | } | |
2135 | } | |
2136 | else if (INTEGRAL_TYPE_P (TREE_TYPE (val))) | |
2137 | { | |
2138 | /* Negative return values are often used to indicate | |
2139 | errors. */ | |
2140 | if (TREE_CODE (val) == INTEGER_CST | |
2141 | && tree_int_cst_sgn (val) < 0) | |
2142 | { | |
2143 | *prediction = NOT_TAKEN; | |
2144 | return PRED_NEGATIVE_RETURN; | |
2145 | } | |
2146 | /* Constant return values seems to be commonly taken. | |
2147 | Zero/one often represent booleans so exclude them from the | |
2148 | heuristics. */ | |
2149 | if (TREE_CONSTANT (val) | |
2150 | && (!integer_zerop (val) && !integer_onep (val))) | |
2151 | { | |
2152 | *prediction = TAKEN; | |
4a4e4487 | 2153 | return PRED_CONST_RETURN; |
f816ec49 | 2154 | } |
2155 | } | |
2156 | return PRED_NO_PREDICTION; | |
2157 | } | |
2158 | ||
2159 | /* Find the basic block with return expression and look up for possible | |
2160 | return value trying to apply RETURN_PREDICTION heuristics. */ | |
2161 | static void | |
d704ea82 | 2162 | apply_return_prediction (void) |
f816ec49 | 2163 | { |
75a70cf9 | 2164 | gimple return_stmt = NULL; |
f816ec49 | 2165 | tree return_val; |
2166 | edge e; | |
75a70cf9 | 2167 | gimple phi; |
f816ec49 | 2168 | int phi_num_args, i; |
2169 | enum br_predictor pred; | |
2170 | enum prediction direction; | |
cd665a06 | 2171 | edge_iterator ei; |
f816ec49 | 2172 | |
cd665a06 | 2173 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) |
f816ec49 | 2174 | { |
2175 | return_stmt = last_stmt (e->src); | |
6313ae8b | 2176 | if (return_stmt |
75a70cf9 | 2177 | && gimple_code (return_stmt) == GIMPLE_RETURN) |
f816ec49 | 2178 | break; |
2179 | } | |
2180 | if (!e) | |
2181 | return; | |
75a70cf9 | 2182 | return_val = gimple_return_retval (return_stmt); |
f816ec49 | 2183 | if (!return_val) |
2184 | return; | |
f816ec49 | 2185 | if (TREE_CODE (return_val) != SSA_NAME |
2186 | || !SSA_NAME_DEF_STMT (return_val) | |
75a70cf9 | 2187 | || gimple_code (SSA_NAME_DEF_STMT (return_val)) != GIMPLE_PHI) |
f816ec49 | 2188 | return; |
75a70cf9 | 2189 | phi = SSA_NAME_DEF_STMT (return_val); |
2190 | phi_num_args = gimple_phi_num_args (phi); | |
f816ec49 | 2191 | pred = return_prediction (PHI_ARG_DEF (phi, 0), &direction); |
2192 | ||
2193 | /* Avoid the degenerate case where all return values form the function | |
2194 | belongs to same category (ie they are all positive constants) | |
2195 | so we can hardly say something about them. */ | |
2196 | for (i = 1; i < phi_num_args; i++) | |
2197 | if (pred != return_prediction (PHI_ARG_DEF (phi, i), &direction)) | |
2198 | break; | |
2199 | if (i != phi_num_args) | |
2200 | for (i = 0; i < phi_num_args; i++) | |
2201 | { | |
2202 | pred = return_prediction (PHI_ARG_DEF (phi, i), &direction); | |
2203 | if (pred != PRED_NO_PREDICTION) | |
5707768a | 2204 | predict_paths_leading_to_edge (gimple_phi_arg_edge (phi, i), pred, |
2205 | direction); | |
f816ec49 | 2206 | } |
2207 | } | |
2208 | ||
2209 | /* Look for basic block that contains unlikely to happen events | |
2210 | (such as noreturn calls) and mark all paths leading to execution | |
2211 | of this basic blocks as unlikely. */ | |
2212 | ||
2213 | static void | |
2214 | tree_bb_level_predictions (void) | |
2215 | { | |
2216 | basic_block bb; | |
9f694a82 | 2217 | bool has_return_edges = false; |
2218 | edge e; | |
2219 | edge_iterator ei; | |
2220 | ||
2221 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) | |
2222 | if (!(e->flags & (EDGE_ABNORMAL | EDGE_FAKE | EDGE_EH))) | |
2223 | { | |
2224 | has_return_edges = true; | |
2225 | break; | |
2226 | } | |
f816ec49 | 2227 | |
d704ea82 | 2228 | apply_return_prediction (); |
f816ec49 | 2229 | |
2230 | FOR_EACH_BB (bb) | |
2231 | { | |
75a70cf9 | 2232 | gimple_stmt_iterator gsi; |
f816ec49 | 2233 | |
1add270f | 2234 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
f816ec49 | 2235 | { |
75a70cf9 | 2236 | gimple stmt = gsi_stmt (gsi); |
5de92639 | 2237 | tree decl; |
3ed4a4a1 | 2238 | |
75a70cf9 | 2239 | if (is_gimple_call (stmt)) |
f816ec49 | 2240 | { |
9f694a82 | 2241 | if ((gimple_call_flags (stmt) & ECF_NORETURN) |
2242 | && has_return_edges) | |
75a70cf9 | 2243 | predict_paths_leading_to (bb, PRED_NORETURN, |
2244 | NOT_TAKEN); | |
2245 | decl = gimple_call_fndecl (stmt); | |
2246 | if (decl | |
2247 | && lookup_attribute ("cold", | |
2248 | DECL_ATTRIBUTES (decl))) | |
2249 | predict_paths_leading_to (bb, PRED_COLD_FUNCTION, | |
2250 | NOT_TAKEN); | |
f816ec49 | 2251 | } |
75a70cf9 | 2252 | else if (gimple_code (stmt) == GIMPLE_PREDICT) |
2253 | { | |
2254 | predict_paths_leading_to (bb, gimple_predict_predictor (stmt), | |
2255 | gimple_predict_outcome (stmt)); | |
1add270f | 2256 | /* Keep GIMPLE_PREDICT around so early inlining will propagate |
2257 | hints to callers. */ | |
75a70cf9 | 2258 | } |
f816ec49 | 2259 | } |
2260 | } | |
f816ec49 | 2261 | } |
2262 | ||
b3723726 | 2263 | #ifdef ENABLE_CHECKING |
2264 | ||
2265 | /* Callback for pointer_map_traverse, asserts that the pointer map is | |
2266 | empty. */ | |
2267 | ||
2268 | static bool | |
f8fd23c0 | 2269 | assert_is_empty (const void *key ATTRIBUTE_UNUSED, void **value, |
b3723726 | 2270 | void *data ATTRIBUTE_UNUSED) |
2271 | { | |
2272 | gcc_assert (!*value); | |
2273 | return false; | |
2274 | } | |
2275 | #endif | |
2276 | ||
675d86b2 | 2277 | /* Predict branch probabilities and estimate profile for basic block BB. */ |
2278 | ||
2279 | static void | |
2280 | tree_estimate_probability_bb (basic_block bb) | |
2281 | { | |
2282 | edge e; | |
2283 | edge_iterator ei; | |
2284 | gimple last; | |
2285 | ||
2286 | FOR_EACH_EDGE (e, ei, bb->succs) | |
2287 | { | |
758a38ab | 2288 | /* Predict edges to user labels with attributes. */ |
2289 | if (e->dest != EXIT_BLOCK_PTR) | |
2290 | { | |
2291 | gimple_stmt_iterator gi; | |
2292 | for (gi = gsi_start_bb (e->dest); !gsi_end_p (gi); gsi_next (&gi)) | |
2293 | { | |
2294 | gimple stmt = gsi_stmt (gi); | |
2295 | tree decl; | |
2296 | ||
2297 | if (gimple_code (stmt) != GIMPLE_LABEL) | |
2298 | break; | |
2299 | decl = gimple_label_label (stmt); | |
2300 | if (DECL_ARTIFICIAL (decl)) | |
2301 | continue; | |
2302 | ||
2303 | /* Finally, we have a user-defined label. */ | |
2304 | if (lookup_attribute ("cold", DECL_ATTRIBUTES (decl))) | |
2305 | predict_edge_def (e, PRED_COLD_LABEL, NOT_TAKEN); | |
2306 | else if (lookup_attribute ("hot", DECL_ATTRIBUTES (decl))) | |
2307 | predict_edge_def (e, PRED_HOT_LABEL, TAKEN); | |
2308 | } | |
2309 | } | |
2310 | ||
675d86b2 | 2311 | /* Predict early returns to be probable, as we've already taken |
2312 | care for error returns and other cases are often used for | |
2313 | fast paths through function. | |
2314 | ||
2315 | Since we've already removed the return statements, we are | |
2316 | looking for CFG like: | |
2317 | ||
2318 | if (conditional) | |
2319 | { | |
2320 | .. | |
2321 | goto return_block | |
2322 | } | |
2323 | some other blocks | |
2324 | return_block: | |
2325 | return_stmt. */ | |
2326 | if (e->dest != bb->next_bb | |
2327 | && e->dest != EXIT_BLOCK_PTR | |
2328 | && single_succ_p (e->dest) | |
2329 | && single_succ_edge (e->dest)->dest == EXIT_BLOCK_PTR | |
2330 | && (last = last_stmt (e->dest)) != NULL | |
2331 | && gimple_code (last) == GIMPLE_RETURN) | |
2332 | { | |
2333 | edge e1; | |
2334 | edge_iterator ei1; | |
2335 | ||
2336 | if (single_succ_p (bb)) | |
2337 | { | |
2338 | FOR_EACH_EDGE (e1, ei1, bb->preds) | |
2339 | if (!predicted_by_p (e1->src, PRED_NULL_RETURN) | |
2340 | && !predicted_by_p (e1->src, PRED_CONST_RETURN) | |
2341 | && !predicted_by_p (e1->src, PRED_NEGATIVE_RETURN)) | |
2342 | predict_edge_def (e1, PRED_TREE_EARLY_RETURN, NOT_TAKEN); | |
2343 | } | |
2344 | else | |
2345 | if (!predicted_by_p (e->src, PRED_NULL_RETURN) | |
2346 | && !predicted_by_p (e->src, PRED_CONST_RETURN) | |
2347 | && !predicted_by_p (e->src, PRED_NEGATIVE_RETURN)) | |
2348 | predict_edge_def (e, PRED_TREE_EARLY_RETURN, NOT_TAKEN); | |
2349 | } | |
2350 | ||
2351 | /* Look for block we are guarding (ie we dominate it, | |
2352 | but it doesn't postdominate us). */ | |
2353 | if (e->dest != EXIT_BLOCK_PTR && e->dest != bb | |
2354 | && dominated_by_p (CDI_DOMINATORS, e->dest, e->src) | |
2355 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e->dest)) | |
2356 | { | |
2357 | gimple_stmt_iterator bi; | |
2358 | ||
2359 | /* The call heuristic claims that a guarded function call | |
2360 | is improbable. This is because such calls are often used | |
2361 | to signal exceptional situations such as printing error | |
2362 | messages. */ | |
2363 | for (bi = gsi_start_bb (e->dest); !gsi_end_p (bi); | |
2364 | gsi_next (&bi)) | |
2365 | { | |
2366 | gimple stmt = gsi_stmt (bi); | |
2367 | if (is_gimple_call (stmt) | |
2368 | /* Constant and pure calls are hardly used to signalize | |
2369 | something exceptional. */ | |
2370 | && gimple_has_side_effects (stmt)) | |
2371 | { | |
2372 | predict_edge_def (e, PRED_CALL, NOT_TAKEN); | |
2373 | break; | |
2374 | } | |
2375 | } | |
2376 | } | |
2377 | } | |
2378 | tree_predict_by_opcode (bb); | |
2379 | } | |
2380 | ||
2381 | /* Predict branch probabilities and estimate profile of the tree CFG. | |
2382 | This function can be called from the loop optimizers to recompute | |
2383 | the profile information. */ | |
2384 | ||
2385 | void | |
4ee9c684 | 2386 | tree_estimate_probability (void) |
2387 | { | |
2388 | basic_block bb; | |
4ee9c684 | 2389 | |
f816ec49 | 2390 | add_noreturn_fake_exit_edges (); |
4ee9c684 | 2391 | connect_infinite_loops_to_exit (); |
d8a0d6b8 | 2392 | /* We use loop_niter_by_eval, which requires that the loops have |
2393 | preheaders. */ | |
2394 | create_preheaders (CP_SIMPLE_PREHEADERS); | |
4ee9c684 | 2395 | calculate_dominance_info (CDI_POST_DOMINATORS); |
2396 | ||
b3723726 | 2397 | bb_predictions = pointer_map_create (); |
f816ec49 | 2398 | tree_bb_level_predictions (); |
d500fef3 | 2399 | record_loop_exits (); |
675d86b2 | 2400 | |
41f75a99 | 2401 | if (number_of_loops (cfun) > 1) |
7194de72 | 2402 | predict_loops (); |
4ee9c684 | 2403 | |
2404 | FOR_EACH_BB (bb) | |
675d86b2 | 2405 | tree_estimate_probability_bb (bb); |
4ee9c684 | 2406 | |
4ee9c684 | 2407 | FOR_EACH_BB (bb) |
3f5be5f4 | 2408 | combine_predictions_for_bb (bb); |
f81d9f78 | 2409 | |
b3723726 | 2410 | #ifdef ENABLE_CHECKING |
2411 | pointer_map_traverse (bb_predictions, assert_is_empty, NULL); | |
2412 | #endif | |
2413 | pointer_map_destroy (bb_predictions); | |
2414 | bb_predictions = NULL; | |
2415 | ||
5327650f | 2416 | estimate_bb_frequencies (false); |
4ee9c684 | 2417 | free_dominance_info (CDI_POST_DOMINATORS); |
41d24834 | 2418 | remove_fake_exit_edges (); |
675d86b2 | 2419 | } |
2420 | ||
2421 | /* Predict branch probabilities and estimate profile of the tree CFG. | |
2422 | This is the driver function for PASS_PROFILE. */ | |
2423 | ||
2424 | static unsigned int | |
2425 | tree_estimate_probability_driver (void) | |
2426 | { | |
2427 | unsigned nb_loops; | |
2428 | ||
b7753059 | 2429 | loop_optimizer_init (LOOPS_NORMAL); |
675d86b2 | 2430 | if (dump_file && (dump_flags & TDF_DETAILS)) |
2431 | flow_loops_dump (dump_file, NULL, 0); | |
2432 | ||
2433 | mark_irreducible_loops (); | |
2434 | ||
41f75a99 | 2435 | nb_loops = number_of_loops (cfun); |
675d86b2 | 2436 | if (nb_loops > 1) |
2437 | scev_initialize (); | |
2438 | ||
2439 | tree_estimate_probability (); | |
2440 | ||
2441 | if (nb_loops > 1) | |
2442 | scev_finalize (); | |
2443 | ||
88e6f696 | 2444 | loop_optimizer_finalize (); |
4ee9c684 | 2445 | if (dump_file && (dump_flags & TDF_DETAILS)) |
75a70cf9 | 2446 | gimple_dump_cfg (dump_file, dump_flags); |
020c749b | 2447 | if (profile_status == PROFILE_ABSENT) |
2448 | profile_status = PROFILE_GUESSED; | |
2a1990e9 | 2449 | return 0; |
59423b59 | 2450 | } |
89cfe6e5 | 2451 | \f |
f0b5f617 | 2452 | /* Predict edges to successors of CUR whose sources are not postdominated by |
d704ea82 | 2453 | BB by PRED and recurse to all postdominators. */ |
f816ec49 | 2454 | |
2455 | static void | |
d704ea82 | 2456 | predict_paths_for_bb (basic_block cur, basic_block bb, |
2457 | enum br_predictor pred, | |
d3443011 | 2458 | enum prediction taken, |
2459 | bitmap visited) | |
f816ec49 | 2460 | { |
2461 | edge e; | |
cd665a06 | 2462 | edge_iterator ei; |
d704ea82 | 2463 | basic_block son; |
f816ec49 | 2464 | |
d704ea82 | 2465 | /* We are looking for all edges forming edge cut induced by |
2466 | set of all blocks postdominated by BB. */ | |
2467 | FOR_EACH_EDGE (e, ei, cur->preds) | |
2468 | if (e->src->index >= NUM_FIXED_BLOCKS | |
2469 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, bb)) | |
f816ec49 | 2470 | { |
f1d5a92b | 2471 | edge e2; |
2472 | edge_iterator ei2; | |
2473 | bool found = false; | |
2474 | ||
5707768a | 2475 | /* Ignore fake edges and eh, we predict them as not taken anyway. */ |
2476 | if (e->flags & (EDGE_EH | EDGE_FAKE)) | |
f1d5a92b | 2477 | continue; |
d704ea82 | 2478 | gcc_assert (bb == cur || dominated_by_p (CDI_POST_DOMINATORS, cur, bb)); |
f1d5a92b | 2479 | |
d3443011 | 2480 | /* See if there is an edge from e->src that is not abnormal |
f1d5a92b | 2481 | and does not lead to BB. */ |
2482 | FOR_EACH_EDGE (e2, ei2, e->src->succs) | |
2483 | if (e2 != e | |
5707768a | 2484 | && !(e2->flags & (EDGE_EH | EDGE_FAKE)) |
f1d5a92b | 2485 | && !dominated_by_p (CDI_POST_DOMINATORS, e2->dest, bb)) |
2486 | { | |
2487 | found = true; | |
2488 | break; | |
2489 | } | |
2490 | ||
2491 | /* If there is non-abnormal path leaving e->src, predict edge | |
2492 | using predictor. Otherwise we need to look for paths | |
d3443011 | 2493 | leading to e->src. |
2494 | ||
2495 | The second may lead to infinite loop in the case we are predicitng | |
2496 | regions that are only reachable by abnormal edges. We simply | |
2497 | prevent visiting given BB twice. */ | |
f1d5a92b | 2498 | if (found) |
2499 | predict_edge_def (e, pred, taken); | |
6e3803fb | 2500 | else if (bitmap_set_bit (visited, e->src->index)) |
d3443011 | 2501 | predict_paths_for_bb (e->src, e->src, pred, taken, visited); |
f816ec49 | 2502 | } |
d704ea82 | 2503 | for (son = first_dom_son (CDI_POST_DOMINATORS, cur); |
2504 | son; | |
2505 | son = next_dom_son (CDI_POST_DOMINATORS, son)) | |
d3443011 | 2506 | predict_paths_for_bb (son, bb, pred, taken, visited); |
d704ea82 | 2507 | } |
f816ec49 | 2508 | |
d704ea82 | 2509 | /* Sets branch probabilities according to PREDiction and |
2510 | FLAGS. */ | |
f816ec49 | 2511 | |
d704ea82 | 2512 | static void |
2513 | predict_paths_leading_to (basic_block bb, enum br_predictor pred, | |
2514 | enum prediction taken) | |
2515 | { | |
d3443011 | 2516 | bitmap visited = BITMAP_ALLOC (NULL); |
2517 | predict_paths_for_bb (bb, bb, pred, taken, visited); | |
2518 | BITMAP_FREE (visited); | |
f816ec49 | 2519 | } |
5707768a | 2520 | |
2521 | /* Like predict_paths_leading_to but take edge instead of basic block. */ | |
2522 | ||
2523 | static void | |
2524 | predict_paths_leading_to_edge (edge e, enum br_predictor pred, | |
2525 | enum prediction taken) | |
2526 | { | |
2527 | bool has_nonloop_edge = false; | |
2528 | edge_iterator ei; | |
2529 | edge e2; | |
2530 | ||
2531 | basic_block bb = e->src; | |
2532 | FOR_EACH_EDGE (e2, ei, bb->succs) | |
2533 | if (e2->dest != e->src && e2->dest != e->dest | |
2534 | && !(e->flags & (EDGE_EH | EDGE_FAKE)) | |
2535 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e2->dest)) | |
2536 | { | |
2537 | has_nonloop_edge = true; | |
2538 | break; | |
2539 | } | |
2540 | if (!has_nonloop_edge) | |
d3443011 | 2541 | { |
2542 | bitmap visited = BITMAP_ALLOC (NULL); | |
2543 | predict_paths_for_bb (bb, bb, pred, taken, visited); | |
2544 | BITMAP_FREE (visited); | |
2545 | } | |
5707768a | 2546 | else |
2547 | predict_edge_def (e, pred, taken); | |
2548 | } | |
cd0fe062 | 2549 | \f |
e725f898 | 2550 | /* This is used to carry information about basic blocks. It is |
f81d9f78 | 2551 | attached to the AUX field of the standard CFG block. */ |
2552 | ||
2553 | typedef struct block_info_def | |
2554 | { | |
2555 | /* Estimated frequency of execution of basic_block. */ | |
e9d7220b | 2556 | sreal frequency; |
f81d9f78 | 2557 | |
2558 | /* To keep queue of basic blocks to process. */ | |
2559 | basic_block next; | |
2560 | ||
4a82352a | 2561 | /* Number of predecessors we need to visit first. */ |
4ad72a03 | 2562 | int npredecessors; |
f81d9f78 | 2563 | } *block_info; |
2564 | ||
2565 | /* Similar information for edges. */ | |
2566 | typedef struct edge_info_def | |
2567 | { | |
77aa6362 | 2568 | /* In case edge is a loopback edge, the probability edge will be reached |
f81d9f78 | 2569 | in case header is. Estimated number of iterations of the loop can be |
56ff4880 | 2570 | then computed as 1 / (1 - back_edge_prob). */ |
e9d7220b | 2571 | sreal back_edge_prob; |
77aa6362 | 2572 | /* True if the edge is a loopback edge in the natural loop. */ |
74cbb553 | 2573 | unsigned int back_edge:1; |
f81d9f78 | 2574 | } *edge_info; |
2575 | ||
2576 | #define BLOCK_INFO(B) ((block_info) (B)->aux) | |
2577 | #define EDGE_INFO(E) ((edge_info) (E)->aux) | |
2578 | ||
2579 | /* Helper function for estimate_bb_frequencies. | |
88e6f696 | 2580 | Propagate the frequencies in blocks marked in |
2581 | TOVISIT, starting in HEAD. */ | |
e6751e9a | 2582 | |
f81d9f78 | 2583 | static void |
88e6f696 | 2584 | propagate_freq (basic_block head, bitmap tovisit) |
f81d9f78 | 2585 | { |
4c26117a | 2586 | basic_block bb; |
2587 | basic_block last; | |
9ea83aa5 | 2588 | unsigned i; |
f81d9f78 | 2589 | edge e; |
2590 | basic_block nextbb; | |
b1bb9b10 | 2591 | bitmap_iterator bi; |
312866af | 2592 | |
4a82352a | 2593 | /* For each basic block we need to visit count number of his predecessors |
312866af | 2594 | we need to visit first. */ |
b1bb9b10 | 2595 | EXECUTE_IF_SET_IN_BITMAP (tovisit, 0, i, bi) |
312866af | 2596 | { |
b1bb9b10 | 2597 | edge_iterator ei; |
2598 | int count = 0; | |
2599 | ||
4d2e5d52 | 2600 | bb = BASIC_BLOCK (i); |
e6751e9a | 2601 | |
b1bb9b10 | 2602 | FOR_EACH_EDGE (e, ei, bb->preds) |
2603 | { | |
2604 | bool visit = bitmap_bit_p (tovisit, e->src->index); | |
2605 | ||
2606 | if (visit && !(e->flags & EDGE_DFS_BACK)) | |
2607 | count++; | |
2608 | else if (visit && dump_file && !EDGE_INFO (e)->back_edge) | |
2609 | fprintf (dump_file, | |
2610 | "Irreducible region hit, ignoring edge to %i->%i\n", | |
2611 | e->src->index, bb->index); | |
312866af | 2612 | } |
9ea83aa5 | 2613 | BLOCK_INFO (bb)->npredecessors = count; |
555e8b05 | 2614 | /* When function never returns, we will never process exit block. */ |
2615 | if (!count && bb == EXIT_BLOCK_PTR) | |
2616 | bb->count = bb->frequency = 0; | |
312866af | 2617 | } |
f81d9f78 | 2618 | |
56ff4880 | 2619 | memcpy (&BLOCK_INFO (head)->frequency, &real_one, sizeof (real_one)); |
4c26117a | 2620 | last = head; |
2621 | for (bb = head; bb; bb = nextbb) | |
f81d9f78 | 2622 | { |
cd665a06 | 2623 | edge_iterator ei; |
e9d7220b | 2624 | sreal cyclic_probability, frequency; |
56ff4880 | 2625 | |
2626 | memcpy (&cyclic_probability, &real_zero, sizeof (real_zero)); | |
2627 | memcpy (&frequency, &real_zero, sizeof (real_zero)); | |
f81d9f78 | 2628 | |
2629 | nextbb = BLOCK_INFO (bb)->next; | |
2630 | BLOCK_INFO (bb)->next = NULL; | |
2631 | ||
2632 | /* Compute frequency of basic block. */ | |
2633 | if (bb != head) | |
2634 | { | |
312866af | 2635 | #ifdef ENABLE_CHECKING |
cd665a06 | 2636 | FOR_EACH_EDGE (e, ei, bb->preds) |
876760f6 | 2637 | gcc_assert (!bitmap_bit_p (tovisit, e->src->index) |
2638 | || (e->flags & EDGE_DFS_BACK)); | |
312866af | 2639 | #endif |
f81d9f78 | 2640 | |
cd665a06 | 2641 | FOR_EACH_EDGE (e, ei, bb->preds) |
f81d9f78 | 2642 | if (EDGE_INFO (e)->back_edge) |
56ff4880 | 2643 | { |
e9d7220b | 2644 | sreal_add (&cyclic_probability, &cyclic_probability, |
2645 | &EDGE_INFO (e)->back_edge_prob); | |
56ff4880 | 2646 | } |
312866af | 2647 | else if (!(e->flags & EDGE_DFS_BACK)) |
56ff4880 | 2648 | { |
e9d7220b | 2649 | sreal tmp; |
56ff4880 | 2650 | |
2651 | /* frequency += (e->probability | |
2652 | * BLOCK_INFO (e->src)->frequency / | |
2653 | REG_BR_PROB_BASE); */ | |
2654 | ||
e9d7220b | 2655 | sreal_init (&tmp, e->probability, 0); |
2656 | sreal_mul (&tmp, &tmp, &BLOCK_INFO (e->src)->frequency); | |
2657 | sreal_mul (&tmp, &tmp, &real_inv_br_prob_base); | |
2658 | sreal_add (&frequency, &frequency, &tmp); | |
56ff4880 | 2659 | } |
2660 | ||
e9d7220b | 2661 | if (sreal_compare (&cyclic_probability, &real_zero) == 0) |
2662 | { | |
2663 | memcpy (&BLOCK_INFO (bb)->frequency, &frequency, | |
2664 | sizeof (frequency)); | |
2665 | } | |
2e3c56e8 | 2666 | else |
2667 | { | |
e9d7220b | 2668 | if (sreal_compare (&cyclic_probability, &real_almost_one) > 0) |
2669 | { | |
2670 | memcpy (&cyclic_probability, &real_almost_one, | |
2671 | sizeof (real_almost_one)); | |
2672 | } | |
f81d9f78 | 2673 | |
d598ad0d | 2674 | /* BLOCK_INFO (bb)->frequency = frequency |
e9d7220b | 2675 | / (1 - cyclic_probability) */ |
f81d9f78 | 2676 | |
e9d7220b | 2677 | sreal_sub (&cyclic_probability, &real_one, &cyclic_probability); |
2678 | sreal_div (&BLOCK_INFO (bb)->frequency, | |
2679 | &frequency, &cyclic_probability); | |
2e3c56e8 | 2680 | } |
f81d9f78 | 2681 | } |
2682 | ||
b1bb9b10 | 2683 | bitmap_clear_bit (tovisit, bb->index); |
f81d9f78 | 2684 | |
c6356c17 | 2685 | e = find_edge (bb, head); |
2686 | if (e) | |
2687 | { | |
2688 | sreal tmp; | |
48e1416a | 2689 | |
c6356c17 | 2690 | /* EDGE_INFO (e)->back_edge_prob |
2691 | = ((e->probability * BLOCK_INFO (bb)->frequency) | |
2692 | / REG_BR_PROB_BASE); */ | |
48e1416a | 2693 | |
c6356c17 | 2694 | sreal_init (&tmp, e->probability, 0); |
2695 | sreal_mul (&tmp, &tmp, &BLOCK_INFO (bb)->frequency); | |
2696 | sreal_mul (&EDGE_INFO (e)->back_edge_prob, | |
2697 | &tmp, &real_inv_br_prob_base); | |
2698 | } | |
f81d9f78 | 2699 | |
e725f898 | 2700 | /* Propagate to successor blocks. */ |
cd665a06 | 2701 | FOR_EACH_EDGE (e, ei, bb->succs) |
312866af | 2702 | if (!(e->flags & EDGE_DFS_BACK) |
4ad72a03 | 2703 | && BLOCK_INFO (e->dest)->npredecessors) |
f81d9f78 | 2704 | { |
4ad72a03 | 2705 | BLOCK_INFO (e->dest)->npredecessors--; |
2706 | if (!BLOCK_INFO (e->dest)->npredecessors) | |
312866af | 2707 | { |
2708 | if (!nextbb) | |
2709 | nextbb = e->dest; | |
2710 | else | |
2711 | BLOCK_INFO (last)->next = e->dest; | |
48e1416a | 2712 | |
312866af | 2713 | last = e->dest; |
2714 | } | |
cd665a06 | 2715 | } |
f81d9f78 | 2716 | } |
2717 | } | |
2718 | ||
5327650f | 2719 | /* Estimate frequencies in loops at same nest level. */ |
e6751e9a | 2720 | |
f81d9f78 | 2721 | static void |
88e6f696 | 2722 | estimate_loops_at_level (struct loop *first_loop) |
f81d9f78 | 2723 | { |
7fb12188 | 2724 | struct loop *loop; |
f81d9f78 | 2725 | |
2726 | for (loop = first_loop; loop; loop = loop->next) | |
2727 | { | |
f81d9f78 | 2728 | edge e; |
7fb12188 | 2729 | basic_block *bbs; |
862be747 | 2730 | unsigned i; |
88e6f696 | 2731 | bitmap tovisit = BITMAP_ALLOC (NULL); |
f81d9f78 | 2732 | |
88e6f696 | 2733 | estimate_loops_at_level (loop->inner); |
d598ad0d | 2734 | |
88e6f696 | 2735 | /* Find current loop back edge and mark it. */ |
2736 | e = loop_latch_edge (loop); | |
2737 | EDGE_INFO (e)->back_edge = 1; | |
7fb12188 | 2738 | |
2739 | bbs = get_loop_body (loop); | |
2740 | for (i = 0; i < loop->num_nodes; i++) | |
b1bb9b10 | 2741 | bitmap_set_bit (tovisit, bbs[i]->index); |
7fb12188 | 2742 | free (bbs); |
88e6f696 | 2743 | propagate_freq (loop->header, tovisit); |
2744 | BITMAP_FREE (tovisit); | |
f81d9f78 | 2745 | } |
2746 | } | |
2747 | ||
fa7637bd | 2748 | /* Propagates frequencies through structure of loops. */ |
88e6f696 | 2749 | |
2750 | static void | |
7194de72 | 2751 | estimate_loops (void) |
88e6f696 | 2752 | { |
2753 | bitmap tovisit = BITMAP_ALLOC (NULL); | |
2754 | basic_block bb; | |
2755 | ||
2756 | /* Start by estimating the frequencies in the loops. */ | |
41f75a99 | 2757 | if (number_of_loops (cfun) > 1) |
7194de72 | 2758 | estimate_loops_at_level (current_loops->tree_root->inner); |
88e6f696 | 2759 | |
2760 | /* Now propagate the frequencies through all the blocks. */ | |
2761 | FOR_ALL_BB (bb) | |
2762 | { | |
2763 | bitmap_set_bit (tovisit, bb->index); | |
2764 | } | |
2765 | propagate_freq (ENTRY_BLOCK_PTR, tovisit); | |
2766 | BITMAP_FREE (tovisit); | |
2767 | } | |
2768 | ||
38a65d4e | 2769 | /* Drop the profile for NODE to guessed, and update its frequency based on |
901d3ddc | 2770 | whether it is expected to be hot given the CALL_COUNT. */ |
38a65d4e | 2771 | |
2772 | static void | |
901d3ddc | 2773 | drop_profile (struct cgraph_node *node, gcov_type call_count) |
38a65d4e | 2774 | { |
2775 | struct function *fn = DECL_STRUCT_FUNCTION (node->decl); | |
901d3ddc | 2776 | /* In the case where this was called by another function with a |
2777 | dropped profile, call_count will be 0. Since there are no | |
2778 | non-zero call counts to this function, we don't know for sure | |
2779 | whether it is hot, and therefore it will be marked normal below. */ | |
2780 | bool hot = maybe_hot_count_p (NULL, call_count); | |
38a65d4e | 2781 | |
2782 | if (dump_file) | |
2783 | fprintf (dump_file, | |
2784 | "Dropping 0 profile for %s/%i. %s based on calls.\n", | |
2785 | cgraph_node_name (node), node->order, | |
2786 | hot ? "Function is hot" : "Function is normal"); | |
2787 | /* We only expect to miss profiles for functions that are reached | |
2788 | via non-zero call edges in cases where the function may have | |
2789 | been linked from another module or library (COMDATs and extern | |
901d3ddc | 2790 | templates). See the comments below for handle_missing_profiles. |
2791 | Also, only warn in cases where the missing counts exceed the | |
2792 | number of training runs. In certain cases with an execv followed | |
2793 | by a no-return call the profile for the no-return call is not | |
2794 | dumped and there can be a mismatch. */ | |
2795 | if (!DECL_COMDAT (node->decl) && !DECL_EXTERNAL (node->decl) | |
2796 | && call_count > profile_info->runs) | |
38a65d4e | 2797 | { |
2798 | if (flag_profile_correction) | |
2799 | { | |
2800 | if (dump_file) | |
2801 | fprintf (dump_file, | |
2802 | "Missing counts for called function %s/%i\n", | |
2803 | cgraph_node_name (node), node->order); | |
2804 | } | |
2805 | else | |
901d3ddc | 2806 | warning (0, "Missing counts for called function %s/%i", |
2807 | cgraph_node_name (node), node->order); | |
38a65d4e | 2808 | } |
2809 | ||
2810 | profile_status_for_function (fn) | |
2811 | = (flag_guess_branch_prob ? PROFILE_GUESSED : PROFILE_ABSENT); | |
2812 | node->frequency | |
2813 | = hot ? NODE_FREQUENCY_HOT : NODE_FREQUENCY_NORMAL; | |
2814 | } | |
2815 | ||
2816 | /* In the case of COMDAT routines, multiple object files will contain the same | |
2817 | function and the linker will select one for the binary. In that case | |
2818 | all the other copies from the profile instrument binary will be missing | |
2819 | profile counts. Look for cases where this happened, due to non-zero | |
2820 | call counts going to 0-count functions, and drop the profile to guessed | |
2821 | so that we can use the estimated probabilities and avoid optimizing only | |
2822 | for size. | |
2823 | ||
2824 | The other case where the profile may be missing is when the routine | |
2825 | is not going to be emitted to the object file, e.g. for "extern template" | |
2826 | class methods. Those will be marked DECL_EXTERNAL. Emit a warning in | |
2827 | all other cases of non-zero calls to 0-count functions. */ | |
2828 | ||
2829 | void | |
2830 | handle_missing_profiles (void) | |
2831 | { | |
2832 | struct cgraph_node *node; | |
2833 | int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); | |
2834 | vec<struct cgraph_node *> worklist; | |
2835 | worklist.create (64); | |
2836 | ||
2837 | /* See if 0 count function has non-0 count callers. In this case we | |
2838 | lost some profile. Drop its function profile to PROFILE_GUESSED. */ | |
2839 | FOR_EACH_DEFINED_FUNCTION (node) | |
2840 | { | |
2841 | struct cgraph_edge *e; | |
2842 | gcov_type call_count = 0; | |
2843 | struct function *fn = DECL_STRUCT_FUNCTION (node->decl); | |
2844 | ||
2845 | if (node->count) | |
2846 | continue; | |
2847 | for (e = node->callers; e; e = e->next_caller) | |
2848 | call_count += e->count; | |
2849 | if (call_count | |
2850 | && fn && fn->cfg | |
2851 | && (call_count * unlikely_count_fraction >= profile_info->runs)) | |
2852 | { | |
901d3ddc | 2853 | drop_profile (node, call_count); |
38a65d4e | 2854 | worklist.safe_push (node); |
2855 | } | |
2856 | } | |
2857 | ||
2858 | /* Propagate the profile dropping to other 0-count COMDATs that are | |
2859 | potentially called by COMDATs we already dropped the profile on. */ | |
2860 | while (worklist.length () > 0) | |
2861 | { | |
2862 | struct cgraph_edge *e; | |
2863 | ||
2864 | node = worklist.pop (); | |
2865 | for (e = node->callees; e; e = e->next_caller) | |
2866 | { | |
2867 | struct cgraph_node *callee = e->callee; | |
2868 | struct function *fn = DECL_STRUCT_FUNCTION (callee->decl); | |
2869 | ||
2870 | if (callee->count > 0) | |
2871 | continue; | |
2872 | if (DECL_COMDAT (callee->decl) && fn && fn->cfg | |
2873 | && profile_status_for_function (fn) == PROFILE_READ) | |
2874 | { | |
901d3ddc | 2875 | drop_profile (node, 0); |
38a65d4e | 2876 | worklist.safe_push (callee); |
2877 | } | |
2878 | } | |
2879 | } | |
2880 | worklist.release (); | |
2881 | } | |
2882 | ||
3f18719c | 2883 | /* Convert counts measured by profile driven feedback to frequencies. |
2884 | Return nonzero iff there was any nonzero execution count. */ | |
e6751e9a | 2885 | |
ffedd254 | 2886 | int |
d598ad0d | 2887 | counts_to_freqs (void) |
f81d9f78 | 2888 | { |
3f18719c | 2889 | gcov_type count_max, true_count_max = 0; |
4c26117a | 2890 | basic_block bb; |
b3d6de89 | 2891 | |
38a65d4e | 2892 | /* Don't overwrite the estimated frequencies when the profile for |
2893 | the function is missing. We may drop this function PROFILE_GUESSED | |
2894 | later in drop_profile (). */ | |
2895 | if (!ENTRY_BLOCK_PTR->count) | |
2896 | return 0; | |
2897 | ||
5fce5299 | 2898 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) |
3f18719c | 2899 | true_count_max = MAX (bb->count, true_count_max); |
f81d9f78 | 2900 | |
3f18719c | 2901 | count_max = MAX (true_count_max, 1); |
4c26117a | 2902 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) |
2903 | bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max; | |
167b550b | 2904 | |
3f18719c | 2905 | return true_count_max; |
f81d9f78 | 2906 | } |
2907 | ||
e6751e9a | 2908 | /* Return true if function is likely to be expensive, so there is no point to |
2909 | optimize performance of prologue, epilogue or do inlining at the expense | |
41a6f238 | 2910 | of code size growth. THRESHOLD is the limit of number of instructions |
e6751e9a | 2911 | function can execute at average to be still considered not expensive. */ |
2912 | ||
f4c0c1a2 | 2913 | bool |
d598ad0d | 2914 | expensive_function_p (int threshold) |
f4c0c1a2 | 2915 | { |
2916 | unsigned int sum = 0; | |
4c26117a | 2917 | basic_block bb; |
27d0c333 | 2918 | unsigned int limit; |
f4c0c1a2 | 2919 | |
2920 | /* We can not compute accurately for large thresholds due to scaled | |
2921 | frequencies. */ | |
876760f6 | 2922 | gcc_assert (threshold <= BB_FREQ_MAX); |
f4c0c1a2 | 2923 | |
4a82352a | 2924 | /* Frequencies are out of range. This either means that function contains |
f4c0c1a2 | 2925 | internal loop executing more than BB_FREQ_MAX times or profile feedback |
2926 | is available and function has not been executed at all. */ | |
2927 | if (ENTRY_BLOCK_PTR->frequency == 0) | |
2928 | return true; | |
195731ad | 2929 | |
f4c0c1a2 | 2930 | /* Maximally BB_FREQ_MAX^2 so overflow won't happen. */ |
2931 | limit = ENTRY_BLOCK_PTR->frequency * threshold; | |
4c26117a | 2932 | FOR_EACH_BB (bb) |
f4c0c1a2 | 2933 | { |
f4c0c1a2 | 2934 | rtx insn; |
2935 | ||
91f71fa3 | 2936 | FOR_BB_INSNS (bb, insn) |
e6751e9a | 2937 | if (active_insn_p (insn)) |
2938 | { | |
2939 | sum += bb->frequency; | |
2940 | if (sum > limit) | |
2941 | return true; | |
f4c0c1a2 | 2942 | } |
2943 | } | |
e6751e9a | 2944 | |
f4c0c1a2 | 2945 | return false; |
2946 | } | |
2947 | ||
5327650f | 2948 | /* Estimate and propagate basic block frequencies using the given branch |
2949 | probabilities. If FORCE is true, the frequencies are used to estimate | |
2950 | the counts even when there are already non-zero profile counts. */ | |
e6751e9a | 2951 | |
4ae20857 | 2952 | void |
5327650f | 2953 | estimate_bb_frequencies (bool force) |
f81d9f78 | 2954 | { |
4c26117a | 2955 | basic_block bb; |
e9d7220b | 2956 | sreal freq_max; |
56ff4880 | 2957 | |
5327650f | 2958 | if (force || profile_status != PROFILE_READ || !counts_to_freqs ()) |
429fa7fa | 2959 | { |
31e4010e | 2960 | static int real_values_initialized = 0; |
2961 | ||
2962 | if (!real_values_initialized) | |
2963 | { | |
fc22704f | 2964 | real_values_initialized = 1; |
31e4010e | 2965 | sreal_init (&real_zero, 0, 0); |
2966 | sreal_init (&real_one, 1, 0); | |
2967 | sreal_init (&real_br_prob_base, REG_BR_PROB_BASE, 0); | |
2968 | sreal_init (&real_bb_freq_max, BB_FREQ_MAX, 0); | |
2969 | sreal_init (&real_one_half, 1, -1); | |
2970 | sreal_div (&real_inv_br_prob_base, &real_one, &real_br_prob_base); | |
2971 | sreal_sub (&real_almost_one, &real_one, &real_inv_br_prob_base); | |
2972 | } | |
f81d9f78 | 2973 | |
429fa7fa | 2974 | mark_dfs_back_edges (); |
429fa7fa | 2975 | |
ea091dfd | 2976 | single_succ_edge (ENTRY_BLOCK_PTR)->probability = REG_BR_PROB_BASE; |
429fa7fa | 2977 | |
2978 | /* Set up block info for each basic block. */ | |
2979 | alloc_aux_for_blocks (sizeof (struct block_info_def)); | |
2980 | alloc_aux_for_edges (sizeof (struct edge_info_def)); | |
4c26117a | 2981 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) |
f81d9f78 | 2982 | { |
f81d9f78 | 2983 | edge e; |
cd665a06 | 2984 | edge_iterator ei; |
429fa7fa | 2985 | |
cd665a06 | 2986 | FOR_EACH_EDGE (e, ei, bb->succs) |
f81d9f78 | 2987 | { |
e9d7220b | 2988 | sreal_init (&EDGE_INFO (e)->back_edge_prob, e->probability, 0); |
2989 | sreal_mul (&EDGE_INFO (e)->back_edge_prob, | |
2990 | &EDGE_INFO (e)->back_edge_prob, | |
2991 | &real_inv_br_prob_base); | |
f81d9f78 | 2992 | } |
f81d9f78 | 2993 | } |
e6751e9a | 2994 | |
5327650f | 2995 | /* First compute frequencies locally for each loop from innermost |
2996 | to outermost to examine frequencies for back edges. */ | |
7194de72 | 2997 | estimate_loops (); |
f81d9f78 | 2998 | |
429fa7fa | 2999 | memcpy (&freq_max, &real_zero, sizeof (real_zero)); |
4c26117a | 3000 | FOR_EACH_BB (bb) |
e9d7220b | 3001 | if (sreal_compare (&freq_max, &BLOCK_INFO (bb)->frequency) < 0) |
3002 | memcpy (&freq_max, &BLOCK_INFO (bb)->frequency, sizeof (freq_max)); | |
2e3c56e8 | 3003 | |
e9d7220b | 3004 | sreal_div (&freq_max, &real_bb_freq_max, &freq_max); |
4c26117a | 3005 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) |
56ff4880 | 3006 | { |
e9d7220b | 3007 | sreal tmp; |
e6751e9a | 3008 | |
e9d7220b | 3009 | sreal_mul (&tmp, &BLOCK_INFO (bb)->frequency, &freq_max); |
3010 | sreal_add (&tmp, &tmp, &real_one_half); | |
3011 | bb->frequency = sreal_to_int (&tmp); | |
429fa7fa | 3012 | } |
e6751e9a | 3013 | |
429fa7fa | 3014 | free_aux_for_blocks (); |
3015 | free_aux_for_edges (); | |
3016 | } | |
3017 | compute_function_frequency (); | |
429fa7fa | 3018 | } |
f81d9f78 | 3019 | |
429fa7fa | 3020 | /* Decide whether function is hot, cold or unlikely executed. */ |
63aab97d | 3021 | void |
d598ad0d | 3022 | compute_function_frequency (void) |
429fa7fa | 3023 | { |
4c26117a | 3024 | basic_block bb; |
fd6a3c41 | 3025 | struct cgraph_node *node = cgraph_get_node (current_function_decl); |
e27f29dd | 3026 | |
0f9fb931 | 3027 | if (DECL_STATIC_CONSTRUCTOR (current_function_decl) |
3028 | || MAIN_NAME_P (DECL_NAME (current_function_decl))) | |
3029 | node->only_called_at_startup = true; | |
3030 | if (DECL_STATIC_DESTRUCTOR (current_function_decl)) | |
3031 | node->only_called_at_exit = true; | |
4c26117a | 3032 | |
e27f29dd | 3033 | if (profile_status != PROFILE_READ) |
5de92639 | 3034 | { |
125b6d78 | 3035 | int flags = flags_from_decl_or_type (current_function_decl); |
5de92639 | 3036 | if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl)) |
3037 | != NULL) | |
125b6d78 | 3038 | node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; |
5de92639 | 3039 | else if (lookup_attribute ("hot", DECL_ATTRIBUTES (current_function_decl)) |
3040 | != NULL) | |
125b6d78 | 3041 | node->frequency = NODE_FREQUENCY_HOT; |
3042 | else if (flags & ECF_NORETURN) | |
3043 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
3044 | else if (MAIN_NAME_P (DECL_NAME (current_function_decl))) | |
3045 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
3046 | else if (DECL_STATIC_CONSTRUCTOR (current_function_decl) | |
3047 | || DECL_STATIC_DESTRUCTOR (current_function_decl)) | |
3048 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
5de92639 | 3049 | return; |
3050 | } | |
e27f29dd | 3051 | |
3052 | /* Only first time try to drop function into unlikely executed. | |
3053 | After inlining the roundoff errors may confuse us. | |
3054 | Ipa-profile pass will drop functions only called from unlikely | |
3055 | functions to unlikely and that is most of what we care about. */ | |
3056 | if (!cfun->after_inlining) | |
3057 | node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; | |
4c26117a | 3058 | FOR_EACH_BB (bb) |
f81d9f78 | 3059 | { |
8d672d12 | 3060 | if (maybe_hot_bb_p (cfun, bb)) |
429fa7fa | 3061 | { |
125b6d78 | 3062 | node->frequency = NODE_FREQUENCY_HOT; |
429fa7fa | 3063 | return; |
3064 | } | |
8d672d12 | 3065 | if (!probably_never_executed_bb_p (cfun, bb)) |
125b6d78 | 3066 | node->frequency = NODE_FREQUENCY_NORMAL; |
f81d9f78 | 3067 | } |
429fa7fa | 3068 | } |
f81d9f78 | 3069 | |
d5043f32 | 3070 | static bool |
3071 | gate_estimate_probability (void) | |
3072 | { | |
3073 | return flag_guess_branch_prob; | |
3074 | } | |
4ee9c684 | 3075 | |
4a1849e3 | 3076 | /* Build PREDICT_EXPR. */ |
3077 | tree | |
3078 | build_predict_expr (enum br_predictor predictor, enum prediction taken) | |
3079 | { | |
08f62b1b | 3080 | tree t = build1 (PREDICT_EXPR, void_type_node, |
b3d480fb | 3081 | build_int_cst (integer_type_node, predictor)); |
b9c74b4d | 3082 | SET_PREDICT_EXPR_OUTCOME (t, taken); |
4a1849e3 | 3083 | return t; |
3084 | } | |
3085 | ||
3086 | const char * | |
3087 | predictor_name (enum br_predictor predictor) | |
3088 | { | |
3089 | return predictor_info[predictor].name; | |
3090 | } | |
3091 | ||
cbe8bda8 | 3092 | namespace { |
3093 | ||
3094 | const pass_data pass_data_profile = | |
3095 | { | |
3096 | GIMPLE_PASS, /* type */ | |
3097 | "profile_estimate", /* name */ | |
3098 | OPTGROUP_NONE, /* optinfo_flags */ | |
3099 | true, /* has_gate */ | |
3100 | true, /* has_execute */ | |
3101 | TV_BRANCH_PROB, /* tv_id */ | |
3102 | PROP_cfg, /* properties_required */ | |
3103 | 0, /* properties_provided */ | |
3104 | 0, /* properties_destroyed */ | |
3105 | 0, /* todo_flags_start */ | |
3106 | TODO_verify_ssa, /* todo_flags_finish */ | |
4ee9c684 | 3107 | }; |
1add270f | 3108 | |
cbe8bda8 | 3109 | class pass_profile : public gimple_opt_pass |
3110 | { | |
3111 | public: | |
9af5ce0c | 3112 | pass_profile (gcc::context *ctxt) |
3113 | : gimple_opt_pass (pass_data_profile, ctxt) | |
cbe8bda8 | 3114 | {} |
3115 | ||
3116 | /* opt_pass methods: */ | |
3117 | bool gate () { return gate_estimate_probability (); } | |
3118 | unsigned int execute () { return tree_estimate_probability_driver (); } | |
3119 | ||
3120 | }; // class pass_profile | |
3121 | ||
3122 | } // anon namespace | |
3123 | ||
3124 | gimple_opt_pass * | |
3125 | make_pass_profile (gcc::context *ctxt) | |
3126 | { | |
3127 | return new pass_profile (ctxt); | |
3128 | } | |
3129 | ||
3130 | namespace { | |
3131 | ||
3132 | const pass_data pass_data_strip_predict_hints = | |
3133 | { | |
3134 | GIMPLE_PASS, /* type */ | |
3135 | "*strip_predict_hints", /* name */ | |
3136 | OPTGROUP_NONE, /* optinfo_flags */ | |
3137 | false, /* has_gate */ | |
3138 | true, /* has_execute */ | |
3139 | TV_BRANCH_PROB, /* tv_id */ | |
3140 | PROP_cfg, /* properties_required */ | |
3141 | 0, /* properties_provided */ | |
3142 | 0, /* properties_destroyed */ | |
3143 | 0, /* todo_flags_start */ | |
3144 | TODO_verify_ssa, /* todo_flags_finish */ | |
1add270f | 3145 | }; |
555e8b05 | 3146 | |
cbe8bda8 | 3147 | class pass_strip_predict_hints : public gimple_opt_pass |
3148 | { | |
3149 | public: | |
9af5ce0c | 3150 | pass_strip_predict_hints (gcc::context *ctxt) |
3151 | : gimple_opt_pass (pass_data_strip_predict_hints, ctxt) | |
cbe8bda8 | 3152 | {} |
3153 | ||
3154 | /* opt_pass methods: */ | |
ae84f584 | 3155 | opt_pass * clone () { return new pass_strip_predict_hints (m_ctxt); } |
cbe8bda8 | 3156 | unsigned int execute () { return strip_predict_hints (); } |
3157 | ||
3158 | }; // class pass_strip_predict_hints | |
3159 | ||
3160 | } // anon namespace | |
3161 | ||
3162 | gimple_opt_pass * | |
3163 | make_pass_strip_predict_hints (gcc::context *ctxt) | |
3164 | { | |
3165 | return new pass_strip_predict_hints (ctxt); | |
3166 | } | |
3167 | ||
555e8b05 | 3168 | /* Rebuild function frequencies. Passes are in general expected to |
3169 | maintain profile by hand, however in some cases this is not possible: | |
3170 | for example when inlining several functions with loops freuqencies might run | |
3171 | out of scale and thus needs to be recomputed. */ | |
3172 | ||
3173 | void | |
3174 | rebuild_frequencies (void) | |
3175 | { | |
4b366dd3 | 3176 | timevar_push (TV_REBUILD_FREQUENCIES); |
5327650f | 3177 | |
3178 | /* When the max bb count in the function is small, there is a higher | |
3179 | chance that there were truncation errors in the integer scaling | |
3180 | of counts by inlining and other optimizations. This could lead | |
3181 | to incorrect classification of code as being cold when it isn't. | |
3182 | In that case, force the estimation of bb counts/frequencies from the | |
3183 | branch probabilities, rather than computing frequencies from counts, | |
3184 | which may also lead to frequencies incorrectly reduced to 0. There | |
3185 | is less precision in the probabilities, so we only do this for small | |
3186 | max counts. */ | |
3187 | gcov_type count_max = 0; | |
3188 | basic_block bb; | |
3189 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb) | |
3190 | count_max = MAX (bb->count, count_max); | |
3191 | ||
3192 | if (profile_status == PROFILE_GUESSED | |
3193 | || (profile_status == PROFILE_READ && count_max < REG_BR_PROB_BASE/10)) | |
555e8b05 | 3194 | { |
3195 | loop_optimizer_init (0); | |
3196 | add_noreturn_fake_exit_edges (); | |
3197 | mark_irreducible_loops (); | |
3198 | connect_infinite_loops_to_exit (); | |
5327650f | 3199 | estimate_bb_frequencies (true); |
555e8b05 | 3200 | remove_fake_exit_edges (); |
3201 | loop_optimizer_finalize (); | |
3202 | } | |
3203 | else if (profile_status == PROFILE_READ) | |
3204 | counts_to_freqs (); | |
3205 | else | |
3206 | gcc_unreachable (); | |
4b366dd3 | 3207 | timevar_pop (TV_REBUILD_FREQUENCIES); |
555e8b05 | 3208 | } |