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59423b59 | 1 | /* Branch prediction routines for the GNU compiler. |
d353bf18 | 2 | Copyright (C) 2000-2015 Free Software Foundation, Inc. |
59423b59 | 3 | |
e6751e9a | 4 | This file is part of GCC. |
59423b59 | 5 | |
e6751e9a | 6 | GCC is free software; you can redistribute it and/or modify it under |
7 | the terms of the GNU General Public License as published by the Free | |
8c4c00c1 | 8 | Software Foundation; either version 3, or (at your option) any later |
e6751e9a | 9 | version. |
59423b59 | 10 | |
e6751e9a | 11 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
12 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 | for more details. | |
59423b59 | 15 | |
e6751e9a | 16 | You should have received a copy of the GNU General Public License |
8c4c00c1 | 17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
59423b59 | 19 | |
20 | /* References: | |
21 | ||
22 | [1] "Branch Prediction for Free" | |
23 | Ball and Larus; PLDI '93. | |
24 | [2] "Static Branch Frequency and Program Profile Analysis" | |
25 | Wu and Larus; MICRO-27. | |
26 | [3] "Corpus-based Static Branch Prediction" | |
04641143 | 27 | Calder, Grunwald, Lindsay, Martin, Mozer, and Zorn; PLDI '95. */ |
59423b59 | 28 | |
29 | ||
30 | #include "config.h" | |
31 | #include "system.h" | |
805e22b2 | 32 | #include "coretypes.h" |
9ef16211 | 33 | #include "backend.h" |
7c29e30e | 34 | #include "target.h" |
35 | #include "rtl.h" | |
59423b59 | 36 | #include "tree.h" |
9ef16211 | 37 | #include "gimple.h" |
7c29e30e | 38 | #include "cfghooks.h" |
39 | #include "tree-pass.h" | |
40 | #include "tm_p.h" | |
9ef16211 | 41 | #include "ssa.h" |
7c29e30e | 42 | #include "expmed.h" |
43 | #include "insn-config.h" | |
44 | #include "regs.h" | |
45 | #include "emit-rtl.h" | |
46 | #include "recog.h" | |
47 | #include "cgraph.h" | |
48 | #include "coverage.h" | |
49 | #include "diagnostic-core.h" | |
50 | #include "gimple-predict.h" | |
9ef16211 | 51 | #include "alias.h" |
b20a8bb4 | 52 | #include "fold-const.h" |
9ed99284 | 53 | #include "calls.h" |
94ea8568 | 54 | #include "cfganal.h" |
94ea8568 | 55 | #include "flags.h" |
886c1262 | 56 | #include "profile.h" |
59423b59 | 57 | #include "except.h" |
d53441c8 | 58 | #include "dojump.h" |
59 | #include "explow.h" | |
d53441c8 | 60 | #include "varasm.h" |
61 | #include "stmt.h" | |
59423b59 | 62 | #include "expr.h" |
e9d7220b | 63 | #include "sreal.h" |
429fa7fa | 64 | #include "params.h" |
862be747 | 65 | #include "cfgloop.h" |
bc61cadb | 66 | #include "internal-fn.h" |
dcf1a1ec | 67 | #include "gimple-iterator.h" |
073c1fd5 | 68 | #include "tree-cfg.h" |
05d9c18a | 69 | #include "tree-ssa-loop-niter.h" |
073c1fd5 | 70 | #include "tree-ssa-loop.h" |
d27b0b64 | 71 | #include "tree-scalar-evolution.h" |
56ff4880 | 72 | |
2e3c56e8 | 73 | /* real constants: 0, 1, 1-1/REG_BR_PROB_BASE, REG_BR_PROB_BASE, |
74 | 1/REG_BR_PROB_BASE, 0.5, BB_FREQ_MAX. */ | |
8201d1f6 | 75 | static sreal real_almost_one, real_br_prob_base, |
e9d7220b | 76 | real_inv_br_prob_base, real_one_half, real_bb_freq_max; |
59423b59 | 77 | |
ee5f6585 | 78 | static void combine_predictions_for_insn (rtx_insn *, basic_block); |
4ee9c684 | 79 | static void dump_prediction (FILE *, enum br_predictor, int, basic_block, int); |
d704ea82 | 80 | static void predict_paths_leading_to (basic_block, enum br_predictor, enum prediction); |
5707768a | 81 | static void predict_paths_leading_to_edge (edge, enum br_predictor, enum prediction); |
ee5f6585 | 82 | static bool can_predict_insn_p (const rtx_insn *); |
5e96f51e | 83 | |
13488c51 | 84 | /* Information we hold about each branch predictor. |
85 | Filled using information from predict.def. */ | |
e6751e9a | 86 | |
13488c51 | 87 | struct predictor_info |
5e96f51e | 88 | { |
e99c3a1d | 89 | const char *const name; /* Name used in the debugging dumps. */ |
90 | const int hitrate; /* Expected hitrate used by | |
91 | predict_insn_def call. */ | |
92 | const int flags; | |
13488c51 | 93 | }; |
5e96f51e | 94 | |
eb429644 | 95 | /* Use given predictor without Dempster-Shaffer theory if it matches |
96 | using first_match heuristics. */ | |
97 | #define PRED_FLAG_FIRST_MATCH 1 | |
98 | ||
99 | /* Recompute hitrate in percent to our representation. */ | |
100 | ||
e6751e9a | 101 | #define HITRATE(VAL) ((int) ((VAL) * REG_BR_PROB_BASE + 50) / 100) |
eb429644 | 102 | |
103 | #define DEF_PREDICTOR(ENUM, NAME, HITRATE, FLAGS) {NAME, HITRATE, FLAGS}, | |
e6751e9a | 104 | static const struct predictor_info predictor_info[]= { |
13488c51 | 105 | #include "predict.def" |
106 | ||
aa40f561 | 107 | /* Upper bound on predictors. */ |
eb429644 | 108 | {NULL, 0, 0} |
13488c51 | 109 | }; |
110 | #undef DEF_PREDICTOR | |
429fa7fa | 111 | |
eb7df8c2 | 112 | /* Return TRUE if frequency FREQ is considered to be hot. */ |
f29b326e | 113 | |
114 | static inline bool | |
8d672d12 | 115 | maybe_hot_frequency_p (struct function *fun, int freq) |
eb7df8c2 | 116 | { |
415d1b9a | 117 | struct cgraph_node *node = cgraph_node::get (fun->decl); |
69ad6a32 | 118 | if (!profile_info |
119 | || !opt_for_fn (fun->decl, flag_branch_probabilities)) | |
eb7df8c2 | 120 | { |
125b6d78 | 121 | if (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED) |
eb7df8c2 | 122 | return false; |
125b6d78 | 123 | if (node->frequency == NODE_FREQUENCY_HOT) |
eb7df8c2 | 124 | return true; |
125 | } | |
3bedbae3 | 126 | if (profile_status_for_fn (fun) == PROFILE_ABSENT) |
aa5f4f32 | 127 | return true; |
125b6d78 | 128 | if (node->frequency == NODE_FREQUENCY_EXECUTED_ONCE |
34154e27 | 129 | && freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency * 2 / 3)) |
125b6d78 | 130 | return false; |
6040d650 | 131 | if (PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) == 0) |
132 | return false; | |
34154e27 | 133 | if (freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency |
8d672d12 | 134 | / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))) |
eb7df8c2 | 135 | return false; |
136 | return true; | |
137 | } | |
138 | ||
9e179a64 | 139 | static gcov_type min_count = -1; |
140 | ||
141 | /* Determine the threshold for hot BB counts. */ | |
142 | ||
143 | gcov_type | |
144 | get_hot_bb_threshold () | |
145 | { | |
146 | gcov_working_set_t *ws; | |
147 | if (min_count == -1) | |
148 | { | |
149 | ws = find_working_set (PARAM_VALUE (HOT_BB_COUNT_WS_PERMILLE)); | |
150 | gcc_assert (ws); | |
151 | min_count = ws->min_counter; | |
152 | } | |
153 | return min_count; | |
154 | } | |
155 | ||
156 | /* Set the threshold for hot BB counts. */ | |
157 | ||
158 | void | |
159 | set_hot_bb_threshold (gcov_type min) | |
160 | { | |
161 | min_count = min; | |
162 | } | |
163 | ||
f29b326e | 164 | /* Return TRUE if frequency FREQ is considered to be hot. */ |
165 | ||
94bed7c3 | 166 | bool |
8d672d12 | 167 | maybe_hot_count_p (struct function *fun, gcov_type count) |
f29b326e | 168 | { |
3bedbae3 | 169 | if (fun && profile_status_for_fn (fun) != PROFILE_READ) |
f29b326e | 170 | return true; |
171 | /* Code executed at most once is not hot. */ | |
172 | if (profile_info->runs >= count) | |
173 | return false; | |
9e179a64 | 174 | return (count >= get_hot_bb_threshold ()); |
f29b326e | 175 | } |
176 | ||
429fa7fa | 177 | /* Return true in case BB can be CPU intensive and should be optimized |
41a6f238 | 178 | for maximal performance. */ |
429fa7fa | 179 | |
180 | bool | |
8d672d12 | 181 | maybe_hot_bb_p (struct function *fun, const_basic_block bb) |
429fa7fa | 182 | { |
8d672d12 | 183 | gcc_checking_assert (fun); |
3bedbae3 | 184 | if (profile_status_for_fn (fun) == PROFILE_READ) |
8d672d12 | 185 | return maybe_hot_count_p (fun, bb->count); |
186 | return maybe_hot_frequency_p (fun, bb->frequency); | |
eb7df8c2 | 187 | } |
188 | ||
189 | /* Return true in case BB can be CPU intensive and should be optimized | |
190 | for maximal performance. */ | |
191 | ||
192 | bool | |
193 | maybe_hot_edge_p (edge e) | |
194 | { | |
f26d8580 | 195 | if (profile_status_for_fn (cfun) == PROFILE_READ) |
8d672d12 | 196 | return maybe_hot_count_p (cfun, e->count); |
197 | return maybe_hot_frequency_p (cfun, EDGE_FREQUENCY (e)); | |
429fa7fa | 198 | } |
199 | ||
dcc9b351 | 200 | /* Return true if profile COUNT and FREQUENCY, or function FUN static |
201 | node frequency reflects never being executed. */ | |
202 | ||
203 | static bool | |
204 | probably_never_executed (struct function *fun, | |
205 | gcov_type count, int frequency) | |
429fa7fa | 206 | { |
8d672d12 | 207 | gcc_checking_assert (fun); |
69ad6a32 | 208 | if (profile_status_for_fn (fun) == PROFILE_READ) |
4befb9f4 | 209 | { |
c1acf60c | 210 | int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); |
211 | if (count * unlikely_count_fraction >= profile_info->runs) | |
4befb9f4 | 212 | return false; |
dcc9b351 | 213 | if (!frequency) |
4befb9f4 | 214 | return true; |
69ad6a32 | 215 | if (!ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency) |
4befb9f4 | 216 | return false; |
69ad6a32 | 217 | if (ENTRY_BLOCK_PTR_FOR_FN (fun)->count) |
4befb9f4 | 218 | { |
c1acf60c | 219 | gcov_type computed_count; |
220 | /* Check for possibility of overflow, in which case entry bb count | |
221 | is large enough to do the division first without losing much | |
222 | precision. */ | |
69ad6a32 | 223 | if (ENTRY_BLOCK_PTR_FOR_FN (fun)->count < REG_BR_PROB_BASE * |
34154e27 | 224 | REG_BR_PROB_BASE) |
c1acf60c | 225 | { |
226 | gcov_type scaled_count | |
69ad6a32 | 227 | = frequency * ENTRY_BLOCK_PTR_FOR_FN (fun)->count * |
34154e27 | 228 | unlikely_count_fraction; |
229 | computed_count = RDIV (scaled_count, | |
69ad6a32 | 230 | ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency); |
c1acf60c | 231 | } |
232 | else | |
233 | { | |
69ad6a32 | 234 | computed_count = RDIV (ENTRY_BLOCK_PTR_FOR_FN (fun)->count, |
235 | ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency); | |
c1acf60c | 236 | computed_count *= frequency * unlikely_count_fraction; |
237 | } | |
238 | if (computed_count >= profile_info->runs) | |
239 | return false; | |
4befb9f4 | 240 | } |
241 | return true; | |
242 | } | |
69ad6a32 | 243 | if ((!profile_info || !(opt_for_fn (fun->decl, flag_branch_probabilities))) |
415d1b9a | 244 | && (cgraph_node::get (fun->decl)->frequency |
fd6a3c41 | 245 | == NODE_FREQUENCY_UNLIKELY_EXECUTED)) |
5de92639 | 246 | return true; |
429fa7fa | 247 | return false; |
248 | } | |
249 | ||
80adc5a6 | 250 | |
dcc9b351 | 251 | /* Return true in case BB is probably never executed. */ |
252 | ||
253 | bool | |
254 | probably_never_executed_bb_p (struct function *fun, const_basic_block bb) | |
255 | { | |
256 | return probably_never_executed (fun, bb->count, bb->frequency); | |
257 | } | |
258 | ||
259 | ||
80adc5a6 | 260 | /* Return true in case edge E is probably never executed. */ |
261 | ||
262 | bool | |
263 | probably_never_executed_edge_p (struct function *fun, edge e) | |
429fa7fa | 264 | { |
dcc9b351 | 265 | return probably_never_executed (fun, e->count, EDGE_FREQUENCY (e)); |
429fa7fa | 266 | } |
267 | ||
cf262be9 | 268 | /* Return true when current function should always be optimized for size. */ |
269 | ||
270 | bool | |
271 | optimize_function_for_size_p (struct function *fun) | |
272 | { | |
cf262be9 | 273 | if (!fun || !fun->decl) |
69ad6a32 | 274 | return optimize_size; |
415d1b9a | 275 | cgraph_node *n = cgraph_node::get (fun->decl); |
276 | return n && n->optimize_for_size_p (); | |
cf262be9 | 277 | } |
278 | ||
533af0db | 279 | /* Return true when current function should always be optimized for speed. */ |
280 | ||
281 | bool | |
282 | optimize_function_for_speed_p (struct function *fun) | |
283 | { | |
284 | return !optimize_function_for_size_p (fun); | |
7dfb44a0 | 285 | } |
286 | ||
287 | /* Return TRUE when BB should be optimized for size. */ | |
288 | ||
289 | bool | |
94ba1cf1 | 290 | optimize_bb_for_size_p (const_basic_block bb) |
7dfb44a0 | 291 | { |
b9ea678c | 292 | return (optimize_function_for_size_p (cfun) |
293 | || (bb && !maybe_hot_bb_p (cfun, bb))); | |
7dfb44a0 | 294 | } |
295 | ||
296 | /* Return TRUE when BB should be optimized for speed. */ | |
297 | ||
298 | bool | |
94ba1cf1 | 299 | optimize_bb_for_speed_p (const_basic_block bb) |
7dfb44a0 | 300 | { |
301 | return !optimize_bb_for_size_p (bb); | |
302 | } | |
303 | ||
304 | /* Return TRUE when BB should be optimized for size. */ | |
305 | ||
306 | bool | |
307 | optimize_edge_for_size_p (edge e) | |
308 | { | |
533af0db | 309 | return optimize_function_for_size_p (cfun) || !maybe_hot_edge_p (e); |
7dfb44a0 | 310 | } |
311 | ||
312 | /* Return TRUE when BB should be optimized for speed. */ | |
313 | ||
314 | bool | |
315 | optimize_edge_for_speed_p (edge e) | |
316 | { | |
317 | return !optimize_edge_for_size_p (e); | |
318 | } | |
319 | ||
320 | /* Return TRUE when BB should be optimized for size. */ | |
321 | ||
322 | bool | |
323 | optimize_insn_for_size_p (void) | |
324 | { | |
533af0db | 325 | return optimize_function_for_size_p (cfun) || !crtl->maybe_hot_insn_p; |
7dfb44a0 | 326 | } |
327 | ||
328 | /* Return TRUE when BB should be optimized for speed. */ | |
329 | ||
330 | bool | |
331 | optimize_insn_for_speed_p (void) | |
332 | { | |
333 | return !optimize_insn_for_size_p (); | |
334 | } | |
335 | ||
94ba1cf1 | 336 | /* Return TRUE when LOOP should be optimized for size. */ |
337 | ||
338 | bool | |
339 | optimize_loop_for_size_p (struct loop *loop) | |
340 | { | |
341 | return optimize_bb_for_size_p (loop->header); | |
342 | } | |
343 | ||
344 | /* Return TRUE when LOOP should be optimized for speed. */ | |
345 | ||
346 | bool | |
347 | optimize_loop_for_speed_p (struct loop *loop) | |
348 | { | |
349 | return optimize_bb_for_speed_p (loop->header); | |
350 | } | |
351 | ||
0bfd8d5c | 352 | /* Return TRUE when LOOP nest should be optimized for speed. */ |
353 | ||
354 | bool | |
355 | optimize_loop_nest_for_speed_p (struct loop *loop) | |
356 | { | |
357 | struct loop *l = loop; | |
358 | if (optimize_loop_for_speed_p (loop)) | |
359 | return true; | |
360 | l = loop->inner; | |
53be41ae | 361 | while (l && l != loop) |
0bfd8d5c | 362 | { |
363 | if (optimize_loop_for_speed_p (l)) | |
364 | return true; | |
365 | if (l->inner) | |
366 | l = l->inner; | |
367 | else if (l->next) | |
368 | l = l->next; | |
369 | else | |
7baffbd3 | 370 | { |
371 | while (l != loop && !l->next) | |
372 | l = loop_outer (l); | |
373 | if (l != loop) | |
374 | l = l->next; | |
375 | } | |
0bfd8d5c | 376 | } |
377 | return false; | |
378 | } | |
379 | ||
380 | /* Return TRUE when LOOP nest should be optimized for size. */ | |
381 | ||
382 | bool | |
383 | optimize_loop_nest_for_size_p (struct loop *loop) | |
384 | { | |
385 | return !optimize_loop_nest_for_speed_p (loop); | |
386 | } | |
387 | ||
4a9d7ef7 | 388 | /* Return true when edge E is likely to be well predictable by branch |
389 | predictor. */ | |
390 | ||
391 | bool | |
392 | predictable_edge_p (edge e) | |
393 | { | |
f26d8580 | 394 | if (profile_status_for_fn (cfun) == PROFILE_ABSENT) |
4a9d7ef7 | 395 | return false; |
396 | if ((e->probability | |
397 | <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100) | |
398 | || (REG_BR_PROB_BASE - e->probability | |
399 | <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100)) | |
400 | return true; | |
401 | return false; | |
402 | } | |
403 | ||
404 | ||
7dfb44a0 | 405 | /* Set RTL expansion for BB profile. */ |
406 | ||
407 | void | |
408 | rtl_profile_for_bb (basic_block bb) | |
409 | { | |
8d672d12 | 410 | crtl->maybe_hot_insn_p = maybe_hot_bb_p (cfun, bb); |
7dfb44a0 | 411 | } |
412 | ||
413 | /* Set RTL expansion for edge profile. */ | |
414 | ||
415 | void | |
416 | rtl_profile_for_edge (edge e) | |
417 | { | |
418 | crtl->maybe_hot_insn_p = maybe_hot_edge_p (e); | |
419 | } | |
420 | ||
421 | /* Set RTL expansion to default mode (i.e. when profile info is not known). */ | |
422 | void | |
423 | default_rtl_profile (void) | |
424 | { | |
425 | crtl->maybe_hot_insn_p = true; | |
426 | } | |
427 | ||
cd0fe062 | 428 | /* Return true if the one of outgoing edges is already predicted by |
429 | PREDICTOR. */ | |
430 | ||
4ee9c684 | 431 | bool |
5493cb9a | 432 | rtl_predicted_by_p (const_basic_block bb, enum br_predictor predictor) |
cd0fe062 | 433 | { |
434 | rtx note; | |
5496dbfc | 435 | if (!INSN_P (BB_END (bb))) |
cd0fe062 | 436 | return false; |
5496dbfc | 437 | for (note = REG_NOTES (BB_END (bb)); note; note = XEXP (note, 1)) |
cd0fe062 | 438 | if (REG_NOTE_KIND (note) == REG_BR_PRED |
439 | && INTVAL (XEXP (XEXP (note, 0), 0)) == (int)predictor) | |
440 | return true; | |
441 | return false; | |
442 | } | |
5e96f51e | 443 | |
eeb030c4 | 444 | /* Structure representing predictions in tree level. */ |
445 | ||
446 | struct edge_prediction { | |
447 | struct edge_prediction *ep_next; | |
448 | edge ep_edge; | |
449 | enum br_predictor ep_predictor; | |
450 | int ep_probability; | |
451 | }; | |
452 | ||
06ecf488 | 453 | /* This map contains for a basic block the list of predictions for the |
454 | outgoing edges. */ | |
455 | ||
456 | static hash_map<const_basic_block, edge_prediction *> *bb_predictions; | |
457 | ||
4ee9c684 | 458 | /* Return true if the one of outgoing edges is already predicted by |
459 | PREDICTOR. */ | |
460 | ||
461 | bool | |
75a70cf9 | 462 | gimple_predicted_by_p (const_basic_block bb, enum br_predictor predictor) |
4ee9c684 | 463 | { |
7ea47fbd | 464 | struct edge_prediction *i; |
06ecf488 | 465 | edge_prediction **preds = bb_predictions->get (bb); |
b3723726 | 466 | |
467 | if (!preds) | |
468 | return false; | |
48e1416a | 469 | |
06ecf488 | 470 | for (i = *preds; i; i = i->ep_next) |
f45e9182 | 471 | if (i->ep_predictor == predictor) |
4ee9c684 | 472 | return true; |
473 | return false; | |
474 | } | |
475 | ||
b41438e5 | 476 | /* Return true when the probability of edge is reliable. |
48e1416a | 477 | |
b41438e5 | 478 | The profile guessing code is good at predicting branch outcome (ie. |
479 | taken/not taken), that is predicted right slightly over 75% of time. | |
ab4f0a13 | 480 | It is however notoriously poor on predicting the probability itself. |
b41438e5 | 481 | In general the profile appear a lot flatter (with probabilities closer |
482 | to 50%) than the reality so it is bad idea to use it to drive optimization | |
483 | such as those disabling dynamic branch prediction for well predictable | |
484 | branches. | |
485 | ||
486 | There are two exceptions - edges leading to noreturn edges and edges | |
487 | predicted by number of iterations heuristics are predicted well. This macro | |
488 | should be able to distinguish those, but at the moment it simply check for | |
489 | noreturn heuristic that is only one giving probability over 99% or bellow | |
ab4f0a13 | 490 | 1%. In future we might want to propagate reliability information across the |
b41438e5 | 491 | CFG if we find this information useful on multiple places. */ |
492 | static bool | |
493 | probability_reliable_p (int prob) | |
494 | { | |
f26d8580 | 495 | return (profile_status_for_fn (cfun) == PROFILE_READ |
496 | || (profile_status_for_fn (cfun) == PROFILE_GUESSED | |
b41438e5 | 497 | && (prob <= HITRATE (1) || prob >= HITRATE (99)))); |
498 | } | |
499 | ||
500 | /* Same predicate as above, working on edges. */ | |
501 | bool | |
7ecb5bb2 | 502 | edge_probability_reliable_p (const_edge e) |
b41438e5 | 503 | { |
504 | return probability_reliable_p (e->probability); | |
505 | } | |
506 | ||
507 | /* Same predicate as edge_probability_reliable_p, working on notes. */ | |
508 | bool | |
7ecb5bb2 | 509 | br_prob_note_reliable_p (const_rtx note) |
b41438e5 | 510 | { |
511 | gcc_assert (REG_NOTE_KIND (note) == REG_BR_PROB); | |
9eb946de | 512 | return probability_reliable_p (XINT (note, 0)); |
b41438e5 | 513 | } |
514 | ||
aa157ca4 | 515 | static void |
ee5f6585 | 516 | predict_insn (rtx_insn *insn, enum br_predictor predictor, int probability) |
13488c51 | 517 | { |
876760f6 | 518 | gcc_assert (any_condjump_p (insn)); |
b28bedce | 519 | if (!flag_guess_branch_prob) |
520 | return; | |
e6751e9a | 521 | |
a1ddb869 | 522 | add_reg_note (insn, REG_BR_PRED, |
523 | gen_rtx_CONCAT (VOIDmode, | |
524 | GEN_INT ((int) predictor), | |
525 | GEN_INT ((int) probability))); | |
13488c51 | 526 | } |
527 | ||
528 | /* Predict insn by given predictor. */ | |
e6751e9a | 529 | |
13488c51 | 530 | void |
ee5f6585 | 531 | predict_insn_def (rtx_insn *insn, enum br_predictor predictor, |
d598ad0d | 532 | enum prediction taken) |
13488c51 | 533 | { |
534 | int probability = predictor_info[(int) predictor].hitrate; | |
e6751e9a | 535 | |
13488c51 | 536 | if (taken != TAKEN) |
537 | probability = REG_BR_PROB_BASE - probability; | |
e6751e9a | 538 | |
13488c51 | 539 | predict_insn (insn, predictor, probability); |
5e96f51e | 540 | } |
541 | ||
542 | /* Predict edge E with given probability if possible. */ | |
e6751e9a | 543 | |
13488c51 | 544 | void |
4ee9c684 | 545 | rtl_predict_edge (edge e, enum br_predictor predictor, int probability) |
5e96f51e | 546 | { |
ee5f6585 | 547 | rtx_insn *last_insn; |
5496dbfc | 548 | last_insn = BB_END (e->src); |
5e96f51e | 549 | |
550 | /* We can store the branch prediction information only about | |
551 | conditional jumps. */ | |
552 | if (!any_condjump_p (last_insn)) | |
553 | return; | |
554 | ||
555 | /* We always store probability of branching. */ | |
556 | if (e->flags & EDGE_FALLTHRU) | |
557 | probability = REG_BR_PROB_BASE - probability; | |
558 | ||
13488c51 | 559 | predict_insn (last_insn, predictor, probability); |
560 | } | |
561 | ||
4ee9c684 | 562 | /* Predict edge E with the given PROBABILITY. */ |
563 | void | |
75a70cf9 | 564 | gimple_predict_edge (edge e, enum br_predictor predictor, int probability) |
4ee9c684 | 565 | { |
f26d8580 | 566 | gcc_assert (profile_status_for_fn (cfun) != PROFILE_GUESSED); |
34154e27 | 567 | if ((e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun) && EDGE_COUNT (e->src->succs) > |
568 | 1) | |
d5043f32 | 569 | && flag_guess_branch_prob && optimize) |
ebd65d12 | 570 | { |
b3723726 | 571 | struct edge_prediction *i = XNEW (struct edge_prediction); |
06ecf488 | 572 | edge_prediction *&preds = bb_predictions->get_or_insert (e->src); |
4ee9c684 | 573 | |
06ecf488 | 574 | i->ep_next = preds; |
575 | preds = i; | |
f45e9182 | 576 | i->ep_probability = probability; |
577 | i->ep_predictor = predictor; | |
578 | i->ep_edge = e; | |
ebd65d12 | 579 | } |
4ee9c684 | 580 | } |
581 | ||
631fa7de | 582 | /* Remove all predictions on given basic block that are attached |
583 | to edge E. */ | |
584 | void | |
585 | remove_predictions_associated_with_edge (edge e) | |
586 | { | |
b3723726 | 587 | if (!bb_predictions) |
588 | return; | |
589 | ||
06ecf488 | 590 | edge_prediction **preds = bb_predictions->get (e->src); |
b3723726 | 591 | |
592 | if (preds) | |
631fa7de | 593 | { |
06ecf488 | 594 | struct edge_prediction **prediction = preds; |
b3723726 | 595 | struct edge_prediction *next; |
596 | ||
631fa7de | 597 | while (*prediction) |
598 | { | |
f45e9182 | 599 | if ((*prediction)->ep_edge == e) |
b3723726 | 600 | { |
601 | next = (*prediction)->ep_next; | |
602 | free (*prediction); | |
603 | *prediction = next; | |
604 | } | |
631fa7de | 605 | else |
f45e9182 | 606 | prediction = &((*prediction)->ep_next); |
631fa7de | 607 | } |
608 | } | |
609 | } | |
610 | ||
b3723726 | 611 | /* Clears the list of predictions stored for BB. */ |
612 | ||
613 | static void | |
614 | clear_bb_predictions (basic_block bb) | |
615 | { | |
06ecf488 | 616 | edge_prediction **preds = bb_predictions->get (bb); |
b3723726 | 617 | struct edge_prediction *pred, *next; |
618 | ||
619 | if (!preds) | |
620 | return; | |
621 | ||
06ecf488 | 622 | for (pred = *preds; pred; pred = next) |
b3723726 | 623 | { |
624 | next = pred->ep_next; | |
625 | free (pred); | |
626 | } | |
627 | *preds = NULL; | |
628 | } | |
629 | ||
1a12dac4 | 630 | /* Return true when we can store prediction on insn INSN. |
631 | At the moment we represent predictions only on conditional | |
632 | jumps, not at computed jump or other complicated cases. */ | |
633 | static bool | |
ee5f6585 | 634 | can_predict_insn_p (const rtx_insn *insn) |
1a12dac4 | 635 | { |
6d7dc5b9 | 636 | return (JUMP_P (insn) |
1a12dac4 | 637 | && any_condjump_p (insn) |
cd665a06 | 638 | && EDGE_COUNT (BLOCK_FOR_INSN (insn)->succs) >= 2); |
1a12dac4 | 639 | } |
640 | ||
13488c51 | 641 | /* Predict edge E by given predictor if possible. */ |
e6751e9a | 642 | |
13488c51 | 643 | void |
d598ad0d | 644 | predict_edge_def (edge e, enum br_predictor predictor, |
645 | enum prediction taken) | |
13488c51 | 646 | { |
647 | int probability = predictor_info[(int) predictor].hitrate; | |
648 | ||
649 | if (taken != TAKEN) | |
650 | probability = REG_BR_PROB_BASE - probability; | |
e6751e9a | 651 | |
13488c51 | 652 | predict_edge (e, predictor, probability); |
653 | } | |
654 | ||
655 | /* Invert all branch predictions or probability notes in the INSN. This needs | |
656 | to be done each time we invert the condition used by the jump. */ | |
e6751e9a | 657 | |
13488c51 | 658 | void |
d598ad0d | 659 | invert_br_probabilities (rtx insn) |
13488c51 | 660 | { |
e6751e9a | 661 | rtx note; |
662 | ||
663 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) | |
664 | if (REG_NOTE_KIND (note) == REG_BR_PROB) | |
9eb946de | 665 | XINT (note, 0) = REG_BR_PROB_BASE - XINT (note, 0); |
e6751e9a | 666 | else if (REG_NOTE_KIND (note) == REG_BR_PRED) |
667 | XEXP (XEXP (note, 0), 1) | |
668 | = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (XEXP (note, 0), 1))); | |
13488c51 | 669 | } |
670 | ||
671 | /* Dump information about the branch prediction to the output file. */ | |
e6751e9a | 672 | |
13488c51 | 673 | static void |
4ee9c684 | 674 | dump_prediction (FILE *file, enum br_predictor predictor, int probability, |
d598ad0d | 675 | basic_block bb, int used) |
13488c51 | 676 | { |
cd665a06 | 677 | edge e; |
678 | edge_iterator ei; | |
13488c51 | 679 | |
4ee9c684 | 680 | if (!file) |
13488c51 | 681 | return; |
682 | ||
cd665a06 | 683 | FOR_EACH_EDGE (e, ei, bb->succs) |
684 | if (! (e->flags & EDGE_FALLTHRU)) | |
685 | break; | |
13488c51 | 686 | |
4ee9c684 | 687 | fprintf (file, " %s heuristics%s: %.1f%%", |
13488c51 | 688 | predictor_info[predictor].name, |
e6751e9a | 689 | used ? "" : " (ignored)", probability * 100.0 / REG_BR_PROB_BASE); |
13488c51 | 690 | |
691 | if (bb->count) | |
17a81216 | 692 | { |
f03df321 | 693 | fprintf (file, " exec %" PRId64, bb->count); |
12c94d25 | 694 | if (e) |
695 | { | |
f03df321 | 696 | fprintf (file, " hit %" PRId64, e->count); |
4ee9c684 | 697 | fprintf (file, " (%.1f%%)", e->count * 100.0 / bb->count); |
12c94d25 | 698 | } |
17a81216 | 699 | } |
e6751e9a | 700 | |
4ee9c684 | 701 | fprintf (file, "\n"); |
13488c51 | 702 | } |
703 | ||
7edd21a5 | 704 | /* We can not predict the probabilities of outgoing edges of bb. Set them |
83c8a977 | 705 | evenly and hope for the best. */ |
706 | static void | |
707 | set_even_probabilities (basic_block bb) | |
708 | { | |
709 | int nedges = 0; | |
710 | edge e; | |
cd665a06 | 711 | edge_iterator ei; |
83c8a977 | 712 | |
cd665a06 | 713 | FOR_EACH_EDGE (e, ei, bb->succs) |
83c8a977 | 714 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
715 | nedges ++; | |
cd665a06 | 716 | FOR_EACH_EDGE (e, ei, bb->succs) |
83c8a977 | 717 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
718 | e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges; | |
719 | else | |
720 | e->probability = 0; | |
721 | } | |
722 | ||
13488c51 | 723 | /* Combine all REG_BR_PRED notes into single probability and attach REG_BR_PROB |
724 | note if not already present. Remove now useless REG_BR_PRED notes. */ | |
e6751e9a | 725 | |
13488c51 | 726 | static void |
ee5f6585 | 727 | combine_predictions_for_insn (rtx_insn *insn, basic_block bb) |
13488c51 | 728 | { |
83c8a977 | 729 | rtx prob_note; |
730 | rtx *pnote; | |
e6751e9a | 731 | rtx note; |
13488c51 | 732 | int best_probability = PROB_EVEN; |
b9c74b4d | 733 | enum br_predictor best_predictor = END_PREDICTORS; |
eb429644 | 734 | int combined_probability = REG_BR_PROB_BASE / 2; |
735 | int d; | |
49d7c0db | 736 | bool first_match = false; |
737 | bool found = false; | |
13488c51 | 738 | |
83c8a977 | 739 | if (!can_predict_insn_p (insn)) |
740 | { | |
741 | set_even_probabilities (bb); | |
742 | return; | |
743 | } | |
744 | ||
745 | prob_note = find_reg_note (insn, REG_BR_PROB, 0); | |
746 | pnote = ®_NOTES (insn); | |
450d042a | 747 | if (dump_file) |
748 | fprintf (dump_file, "Predictions for insn %i bb %i\n", INSN_UID (insn), | |
b3d6de89 | 749 | bb->index); |
13488c51 | 750 | |
751 | /* We implement "first match" heuristics and use probability guessed | |
4ee9c684 | 752 | by predictor with smallest index. */ |
e6751e9a | 753 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) |
754 | if (REG_NOTE_KIND (note) == REG_BR_PRED) | |
755 | { | |
bc620c5c | 756 | enum br_predictor predictor = ((enum br_predictor) |
757 | INTVAL (XEXP (XEXP (note, 0), 0))); | |
e6751e9a | 758 | int probability = INTVAL (XEXP (XEXP (note, 0), 1)); |
759 | ||
760 | found = true; | |
761 | if (best_predictor > predictor) | |
762 | best_probability = probability, best_predictor = predictor; | |
763 | ||
764 | d = (combined_probability * probability | |
765 | + (REG_BR_PROB_BASE - combined_probability) | |
766 | * (REG_BR_PROB_BASE - probability)); | |
767 | ||
768 | /* Use FP math to avoid overflows of 32bit integers. */ | |
c4a616f2 | 769 | if (d == 0) |
770 | /* If one probability is 0% and one 100%, avoid division by zero. */ | |
771 | combined_probability = REG_BR_PROB_BASE / 2; | |
772 | else | |
773 | combined_probability = (((double) combined_probability) * probability | |
774 | * REG_BR_PROB_BASE / d + 0.5); | |
e6751e9a | 775 | } |
776 | ||
777 | /* Decide which heuristic to use. In case we didn't match anything, | |
778 | use no_prediction heuristic, in case we did match, use either | |
49d7c0db | 779 | first match or Dempster-Shaffer theory depending on the flags. */ |
780 | ||
eb429644 | 781 | if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH) |
49d7c0db | 782 | first_match = true; |
783 | ||
784 | if (!found) | |
4ee9c684 | 785 | dump_prediction (dump_file, PRED_NO_PREDICTION, |
786 | combined_probability, bb, true); | |
49d7c0db | 787 | else |
788 | { | |
4ee9c684 | 789 | dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, |
790 | bb, !first_match); | |
791 | dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, | |
792 | bb, first_match); | |
49d7c0db | 793 | } |
794 | ||
795 | if (first_match) | |
eb429644 | 796 | combined_probability = best_probability; |
4ee9c684 | 797 | dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); |
49d7c0db | 798 | |
799 | while (*pnote) | |
800 | { | |
801 | if (REG_NOTE_KIND (*pnote) == REG_BR_PRED) | |
802 | { | |
bc620c5c | 803 | enum br_predictor predictor = ((enum br_predictor) |
804 | INTVAL (XEXP (XEXP (*pnote, 0), 0))); | |
49d7c0db | 805 | int probability = INTVAL (XEXP (XEXP (*pnote, 0), 1)); |
806 | ||
4ee9c684 | 807 | dump_prediction (dump_file, predictor, probability, bb, |
49d7c0db | 808 | !first_match || best_predictor == predictor); |
195731ad | 809 | *pnote = XEXP (*pnote, 1); |
49d7c0db | 810 | } |
811 | else | |
195731ad | 812 | pnote = &XEXP (*pnote, 1); |
49d7c0db | 813 | } |
e6751e9a | 814 | |
13488c51 | 815 | if (!prob_note) |
816 | { | |
9eb946de | 817 | add_int_reg_note (insn, REG_BR_PROB, combined_probability); |
e6751e9a | 818 | |
eb429644 | 819 | /* Save the prediction into CFG in case we are seeing non-degenerated |
820 | conditional jump. */ | |
ea091dfd | 821 | if (!single_succ_p (bb)) |
eb429644 | 822 | { |
823 | BRANCH_EDGE (bb)->probability = combined_probability; | |
e6751e9a | 824 | FALLTHRU_EDGE (bb)->probability |
825 | = REG_BR_PROB_BASE - combined_probability; | |
eb429644 | 826 | } |
13488c51 | 827 | } |
ea091dfd | 828 | else if (!single_succ_p (bb)) |
d8c70625 | 829 | { |
9eb946de | 830 | int prob = XINT (prob_note, 0); |
d8c70625 | 831 | |
832 | BRANCH_EDGE (bb)->probability = prob; | |
833 | FALLTHRU_EDGE (bb)->probability = REG_BR_PROB_BASE - prob; | |
834 | } | |
835 | else | |
ea091dfd | 836 | single_succ_edge (bb)->probability = REG_BR_PROB_BASE; |
5e96f51e | 837 | } |
838 | ||
4ee9c684 | 839 | /* Combine predictions into single probability and store them into CFG. |
840 | Remove now useless prediction entries. */ | |
59423b59 | 841 | |
4ee9c684 | 842 | static void |
3f5be5f4 | 843 | combine_predictions_for_bb (basic_block bb) |
59423b59 | 844 | { |
4ee9c684 | 845 | int best_probability = PROB_EVEN; |
b9c74b4d | 846 | enum br_predictor best_predictor = END_PREDICTORS; |
4ee9c684 | 847 | int combined_probability = REG_BR_PROB_BASE / 2; |
848 | int d; | |
849 | bool first_match = false; | |
850 | bool found = false; | |
851 | struct edge_prediction *pred; | |
852 | int nedges = 0; | |
853 | edge e, first = NULL, second = NULL; | |
cd665a06 | 854 | edge_iterator ei; |
59423b59 | 855 | |
cd665a06 | 856 | FOR_EACH_EDGE (e, ei, bb->succs) |
4ee9c684 | 857 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
858 | { | |
cd665a06 | 859 | nedges ++; |
4ee9c684 | 860 | if (first && !second) |
861 | second = e; | |
862 | if (!first) | |
863 | first = e; | |
864 | } | |
865 | ||
48e1416a | 866 | /* When there is no successor or only one choice, prediction is easy. |
4ee9c684 | 867 | |
868 | We are lazy for now and predict only basic blocks with two outgoing | |
869 | edges. It is possible to predict generic case too, but we have to | |
870 | ignore first match heuristics and do more involved combining. Implement | |
871 | this later. */ | |
872 | if (nedges != 2) | |
873 | { | |
83c8a977 | 874 | if (!bb->count) |
875 | set_even_probabilities (bb); | |
b3723726 | 876 | clear_bb_predictions (bb); |
3f5be5f4 | 877 | if (dump_file) |
878 | fprintf (dump_file, "%i edges in bb %i predicted to even probabilities\n", | |
4ee9c684 | 879 | nedges, bb->index); |
880 | return; | |
881 | } | |
882 | ||
3f5be5f4 | 883 | if (dump_file) |
884 | fprintf (dump_file, "Predictions for bb %i\n", bb->index); | |
4ee9c684 | 885 | |
06ecf488 | 886 | edge_prediction **preds = bb_predictions->get (bb); |
b3723726 | 887 | if (preds) |
4ee9c684 | 888 | { |
b3723726 | 889 | /* We implement "first match" heuristics and use probability guessed |
890 | by predictor with smallest index. */ | |
06ecf488 | 891 | for (pred = *preds; pred; pred = pred->ep_next) |
b3723726 | 892 | { |
b9c74b4d | 893 | enum br_predictor predictor = pred->ep_predictor; |
b3723726 | 894 | int probability = pred->ep_probability; |
4ee9c684 | 895 | |
b3723726 | 896 | if (pred->ep_edge != first) |
897 | probability = REG_BR_PROB_BASE - probability; | |
4ee9c684 | 898 | |
b3723726 | 899 | found = true; |
9f694a82 | 900 | /* First match heuristics would be widly confused if we predicted |
901 | both directions. */ | |
b3723726 | 902 | if (best_predictor > predictor) |
9f694a82 | 903 | { |
904 | struct edge_prediction *pred2; | |
905 | int prob = probability; | |
906 | ||
c83059be | 907 | for (pred2 = (struct edge_prediction *) *preds; |
908 | pred2; pred2 = pred2->ep_next) | |
9f694a82 | 909 | if (pred2 != pred && pred2->ep_predictor == pred->ep_predictor) |
910 | { | |
911 | int probability2 = pred->ep_probability; | |
912 | ||
913 | if (pred2->ep_edge != first) | |
914 | probability2 = REG_BR_PROB_BASE - probability2; | |
915 | ||
48e1416a | 916 | if ((probability < REG_BR_PROB_BASE / 2) != |
9f694a82 | 917 | (probability2 < REG_BR_PROB_BASE / 2)) |
918 | break; | |
919 | ||
920 | /* If the same predictor later gave better result, go for it! */ | |
921 | if ((probability >= REG_BR_PROB_BASE / 2 && (probability2 > probability)) | |
922 | || (probability <= REG_BR_PROB_BASE / 2 && (probability2 < probability))) | |
923 | prob = probability2; | |
924 | } | |
925 | if (!pred2) | |
926 | best_probability = prob, best_predictor = predictor; | |
927 | } | |
4ee9c684 | 928 | |
b3723726 | 929 | d = (combined_probability * probability |
930 | + (REG_BR_PROB_BASE - combined_probability) | |
931 | * (REG_BR_PROB_BASE - probability)); | |
4ee9c684 | 932 | |
b3723726 | 933 | /* Use FP math to avoid overflows of 32bit integers. */ |
934 | if (d == 0) | |
935 | /* If one probability is 0% and one 100%, avoid division by zero. */ | |
936 | combined_probability = REG_BR_PROB_BASE / 2; | |
937 | else | |
938 | combined_probability = (((double) combined_probability) | |
939 | * probability | |
940 | * REG_BR_PROB_BASE / d + 0.5); | |
941 | } | |
4ee9c684 | 942 | } |
943 | ||
944 | /* Decide which heuristic to use. In case we didn't match anything, | |
945 | use no_prediction heuristic, in case we did match, use either | |
946 | first match or Dempster-Shaffer theory depending on the flags. */ | |
947 | ||
948 | if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH) | |
949 | first_match = true; | |
950 | ||
951 | if (!found) | |
3f5be5f4 | 952 | dump_prediction (dump_file, PRED_NO_PREDICTION, combined_probability, bb, true); |
4ee9c684 | 953 | else |
954 | { | |
3f5be5f4 | 955 | dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, bb, |
4ee9c684 | 956 | !first_match); |
3f5be5f4 | 957 | dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, bb, |
4ee9c684 | 958 | first_match); |
959 | } | |
960 | ||
961 | if (first_match) | |
962 | combined_probability = best_probability; | |
3f5be5f4 | 963 | dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); |
4ee9c684 | 964 | |
b3723726 | 965 | if (preds) |
4ee9c684 | 966 | { |
4077bf7a | 967 | for (pred = (struct edge_prediction *) *preds; pred; pred = pred->ep_next) |
b3723726 | 968 | { |
b9c74b4d | 969 | enum br_predictor predictor = pred->ep_predictor; |
b3723726 | 970 | int probability = pred->ep_probability; |
4ee9c684 | 971 | |
b3723726 | 972 | if (pred->ep_edge != EDGE_SUCC (bb, 0)) |
973 | probability = REG_BR_PROB_BASE - probability; | |
974 | dump_prediction (dump_file, predictor, probability, bb, | |
975 | !first_match || best_predictor == predictor); | |
976 | } | |
4ee9c684 | 977 | } |
b3723726 | 978 | clear_bb_predictions (bb); |
4ee9c684 | 979 | |
83c8a977 | 980 | if (!bb->count) |
981 | { | |
982 | first->probability = combined_probability; | |
983 | second->probability = REG_BR_PROB_BASE - combined_probability; | |
984 | } | |
4ee9c684 | 985 | } |
986 | ||
fd757b76 | 987 | /* Check if T1 and T2 satisfy the IV_COMPARE condition. |
988 | Return the SSA_NAME if the condition satisfies, NULL otherwise. | |
989 | ||
990 | T1 and T2 should be one of the following cases: | |
991 | 1. T1 is SSA_NAME, T2 is NULL | |
992 | 2. T1 is SSA_NAME, T2 is INTEGER_CST between [-4, 4] | |
993 | 3. T2 is SSA_NAME, T1 is INTEGER_CST between [-4, 4] */ | |
994 | ||
995 | static tree | |
996 | strips_small_constant (tree t1, tree t2) | |
997 | { | |
998 | tree ret = NULL; | |
999 | int value = 0; | |
1000 | ||
1001 | if (!t1) | |
1002 | return NULL; | |
1003 | else if (TREE_CODE (t1) == SSA_NAME) | |
1004 | ret = t1; | |
e913b5cd | 1005 | else if (tree_fits_shwi_p (t1)) |
1006 | value = tree_to_shwi (t1); | |
fd757b76 | 1007 | else |
1008 | return NULL; | |
1009 | ||
1010 | if (!t2) | |
1011 | return ret; | |
e913b5cd | 1012 | else if (tree_fits_shwi_p (t2)) |
1013 | value = tree_to_shwi (t2); | |
fd757b76 | 1014 | else if (TREE_CODE (t2) == SSA_NAME) |
1015 | { | |
1016 | if (ret) | |
1017 | return NULL; | |
1018 | else | |
1019 | ret = t2; | |
1020 | } | |
1021 | ||
1022 | if (value <= 4 && value >= -4) | |
1023 | return ret; | |
1024 | else | |
1025 | return NULL; | |
1026 | } | |
1027 | ||
1028 | /* Return the SSA_NAME in T or T's operands. | |
1029 | Return NULL if SSA_NAME cannot be found. */ | |
1030 | ||
1031 | static tree | |
1032 | get_base_value (tree t) | |
1033 | { | |
1034 | if (TREE_CODE (t) == SSA_NAME) | |
1035 | return t; | |
1036 | ||
1037 | if (!BINARY_CLASS_P (t)) | |
1038 | return NULL; | |
1039 | ||
1040 | switch (TREE_OPERAND_LENGTH (t)) | |
1041 | { | |
1042 | case 1: | |
1043 | return strips_small_constant (TREE_OPERAND (t, 0), NULL); | |
1044 | case 2: | |
1045 | return strips_small_constant (TREE_OPERAND (t, 0), | |
1046 | TREE_OPERAND (t, 1)); | |
1047 | default: | |
1048 | return NULL; | |
1049 | } | |
1050 | } | |
1051 | ||
1052 | /* Check the compare STMT in LOOP. If it compares an induction | |
1053 | variable to a loop invariant, return true, and save | |
1054 | LOOP_INVARIANT, COMPARE_CODE and LOOP_STEP. | |
1055 | Otherwise return false and set LOOP_INVAIANT to NULL. */ | |
1056 | ||
1057 | static bool | |
1a91d914 | 1058 | is_comparison_with_loop_invariant_p (gcond *stmt, struct loop *loop, |
fd757b76 | 1059 | tree *loop_invariant, |
1060 | enum tree_code *compare_code, | |
b3269f54 | 1061 | tree *loop_step, |
fd757b76 | 1062 | tree *loop_iv_base) |
1063 | { | |
1064 | tree op0, op1, bound, base; | |
1065 | affine_iv iv0, iv1; | |
1066 | enum tree_code code; | |
b3269f54 | 1067 | tree step; |
fd757b76 | 1068 | |
1069 | code = gimple_cond_code (stmt); | |
1070 | *loop_invariant = NULL; | |
1071 | ||
1072 | switch (code) | |
1073 | { | |
1074 | case GT_EXPR: | |
1075 | case GE_EXPR: | |
1076 | case NE_EXPR: | |
1077 | case LT_EXPR: | |
1078 | case LE_EXPR: | |
1079 | case EQ_EXPR: | |
1080 | break; | |
1081 | ||
1082 | default: | |
1083 | return false; | |
1084 | } | |
1085 | ||
1086 | op0 = gimple_cond_lhs (stmt); | |
1087 | op1 = gimple_cond_rhs (stmt); | |
1088 | ||
1089 | if ((TREE_CODE (op0) != SSA_NAME && TREE_CODE (op0) != INTEGER_CST) | |
1090 | || (TREE_CODE (op1) != SSA_NAME && TREE_CODE (op1) != INTEGER_CST)) | |
1091 | return false; | |
1092 | if (!simple_iv (loop, loop_containing_stmt (stmt), op0, &iv0, true)) | |
1093 | return false; | |
1094 | if (!simple_iv (loop, loop_containing_stmt (stmt), op1, &iv1, true)) | |
1095 | return false; | |
1096 | if (TREE_CODE (iv0.step) != INTEGER_CST | |
1097 | || TREE_CODE (iv1.step) != INTEGER_CST) | |
1098 | return false; | |
1099 | if ((integer_zerop (iv0.step) && integer_zerop (iv1.step)) | |
1100 | || (!integer_zerop (iv0.step) && !integer_zerop (iv1.step))) | |
1101 | return false; | |
1102 | ||
1103 | if (integer_zerop (iv0.step)) | |
1104 | { | |
1105 | if (code != NE_EXPR && code != EQ_EXPR) | |
1106 | code = invert_tree_comparison (code, false); | |
1107 | bound = iv0.base; | |
1108 | base = iv1.base; | |
e913b5cd | 1109 | if (tree_fits_shwi_p (iv1.step)) |
b3269f54 | 1110 | step = iv1.step; |
fd757b76 | 1111 | else |
1112 | return false; | |
1113 | } | |
1114 | else | |
1115 | { | |
1116 | bound = iv1.base; | |
1117 | base = iv0.base; | |
e913b5cd | 1118 | if (tree_fits_shwi_p (iv0.step)) |
b3269f54 | 1119 | step = iv0.step; |
fd757b76 | 1120 | else |
1121 | return false; | |
1122 | } | |
1123 | ||
1124 | if (TREE_CODE (bound) != INTEGER_CST) | |
1125 | bound = get_base_value (bound); | |
1126 | if (!bound) | |
1127 | return false; | |
1128 | if (TREE_CODE (base) != INTEGER_CST) | |
1129 | base = get_base_value (base); | |
1130 | if (!base) | |
1131 | return false; | |
1132 | ||
1133 | *loop_invariant = bound; | |
1134 | *compare_code = code; | |
1135 | *loop_step = step; | |
1136 | *loop_iv_base = base; | |
1137 | return true; | |
1138 | } | |
1139 | ||
1140 | /* Compare two SSA_NAMEs: returns TRUE if T1 and T2 are value coherent. */ | |
1141 | ||
1142 | static bool | |
1143 | expr_coherent_p (tree t1, tree t2) | |
1144 | { | |
42acab1c | 1145 | gimple *stmt; |
fd757b76 | 1146 | tree ssa_name_1 = NULL; |
1147 | tree ssa_name_2 = NULL; | |
1148 | ||
1149 | gcc_assert (TREE_CODE (t1) == SSA_NAME || TREE_CODE (t1) == INTEGER_CST); | |
1150 | gcc_assert (TREE_CODE (t2) == SSA_NAME || TREE_CODE (t2) == INTEGER_CST); | |
1151 | ||
1152 | if (t1 == t2) | |
1153 | return true; | |
1154 | ||
1155 | if (TREE_CODE (t1) == INTEGER_CST && TREE_CODE (t2) == INTEGER_CST) | |
1156 | return true; | |
1157 | if (TREE_CODE (t1) == INTEGER_CST || TREE_CODE (t2) == INTEGER_CST) | |
1158 | return false; | |
1159 | ||
1160 | /* Check to see if t1 is expressed/defined with t2. */ | |
1161 | stmt = SSA_NAME_DEF_STMT (t1); | |
1162 | gcc_assert (stmt != NULL); | |
1163 | if (is_gimple_assign (stmt)) | |
1164 | { | |
1165 | ssa_name_1 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); | |
1166 | if (ssa_name_1 && ssa_name_1 == t2) | |
1167 | return true; | |
1168 | } | |
1169 | ||
1170 | /* Check to see if t2 is expressed/defined with t1. */ | |
1171 | stmt = SSA_NAME_DEF_STMT (t2); | |
1172 | gcc_assert (stmt != NULL); | |
1173 | if (is_gimple_assign (stmt)) | |
1174 | { | |
1175 | ssa_name_2 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); | |
1176 | if (ssa_name_2 && ssa_name_2 == t1) | |
1177 | return true; | |
1178 | } | |
1179 | ||
1180 | /* Compare if t1 and t2's def_stmts are identical. */ | |
1181 | if (ssa_name_2 != NULL && ssa_name_1 == ssa_name_2) | |
1182 | return true; | |
1183 | else | |
1184 | return false; | |
1185 | } | |
1186 | ||
1187 | /* Predict branch probability of BB when BB contains a branch that compares | |
1188 | an induction variable in LOOP with LOOP_IV_BASE_VAR to LOOP_BOUND_VAR. The | |
1189 | loop exit is compared using LOOP_BOUND_CODE, with step of LOOP_BOUND_STEP. | |
1190 | ||
1191 | E.g. | |
1192 | for (int i = 0; i < bound; i++) { | |
1193 | if (i < bound - 2) | |
1194 | computation_1(); | |
1195 | else | |
1196 | computation_2(); | |
1197 | } | |
1198 | ||
1199 | In this loop, we will predict the branch inside the loop to be taken. */ | |
1200 | ||
1201 | static void | |
1202 | predict_iv_comparison (struct loop *loop, basic_block bb, | |
1203 | tree loop_bound_var, | |
1204 | tree loop_iv_base_var, | |
1205 | enum tree_code loop_bound_code, | |
1206 | int loop_bound_step) | |
1207 | { | |
42acab1c | 1208 | gimple *stmt; |
fd757b76 | 1209 | tree compare_var, compare_base; |
1210 | enum tree_code compare_code; | |
b3269f54 | 1211 | tree compare_step_var; |
fd757b76 | 1212 | edge then_edge; |
1213 | edge_iterator ei; | |
1214 | ||
1215 | if (predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED) | |
1216 | || predicted_by_p (bb, PRED_LOOP_ITERATIONS) | |
1217 | || predicted_by_p (bb, PRED_LOOP_EXIT)) | |
1218 | return; | |
1219 | ||
1220 | stmt = last_stmt (bb); | |
1221 | if (!stmt || gimple_code (stmt) != GIMPLE_COND) | |
1222 | return; | |
1a91d914 | 1223 | if (!is_comparison_with_loop_invariant_p (as_a <gcond *> (stmt), |
1224 | loop, &compare_var, | |
fd757b76 | 1225 | &compare_code, |
b3269f54 | 1226 | &compare_step_var, |
fd757b76 | 1227 | &compare_base)) |
1228 | return; | |
1229 | ||
1230 | /* Find the taken edge. */ | |
1231 | FOR_EACH_EDGE (then_edge, ei, bb->succs) | |
1232 | if (then_edge->flags & EDGE_TRUE_VALUE) | |
1233 | break; | |
1234 | ||
1235 | /* When comparing an IV to a loop invariant, NE is more likely to be | |
1236 | taken while EQ is more likely to be not-taken. */ | |
1237 | if (compare_code == NE_EXPR) | |
1238 | { | |
1239 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1240 | return; | |
1241 | } | |
1242 | else if (compare_code == EQ_EXPR) | |
1243 | { | |
1244 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1245 | return; | |
1246 | } | |
1247 | ||
1248 | if (!expr_coherent_p (loop_iv_base_var, compare_base)) | |
1249 | return; | |
1250 | ||
1251 | /* If loop bound, base and compare bound are all constants, we can | |
1252 | calculate the probability directly. */ | |
e913b5cd | 1253 | if (tree_fits_shwi_p (loop_bound_var) |
1254 | && tree_fits_shwi_p (compare_var) | |
1255 | && tree_fits_shwi_p (compare_base)) | |
fd757b76 | 1256 | { |
1257 | int probability; | |
e913b5cd | 1258 | bool overflow, overall_overflow = false; |
ab2c1de8 | 1259 | widest_int compare_count, tem; |
b3269f54 | 1260 | |
b3269f54 | 1261 | /* (loop_bound - base) / compare_step */ |
c311b856 | 1262 | tem = wi::sub (wi::to_widest (loop_bound_var), |
1263 | wi::to_widest (compare_base), SIGNED, &overflow); | |
e913b5cd | 1264 | overall_overflow |= overflow; |
c311b856 | 1265 | widest_int loop_count = wi::div_trunc (tem, |
1266 | wi::to_widest (compare_step_var), | |
1267 | SIGNED, &overflow); | |
e913b5cd | 1268 | overall_overflow |= overflow; |
1269 | ||
c311b856 | 1270 | if (!wi::neg_p (wi::to_widest (compare_step_var)) |
fd757b76 | 1271 | ^ (compare_code == LT_EXPR || compare_code == LE_EXPR)) |
b3269f54 | 1272 | { |
1273 | /* (loop_bound - compare_bound) / compare_step */ | |
c311b856 | 1274 | tem = wi::sub (wi::to_widest (loop_bound_var), |
1275 | wi::to_widest (compare_var), SIGNED, &overflow); | |
e913b5cd | 1276 | overall_overflow |= overflow; |
c311b856 | 1277 | compare_count = wi::div_trunc (tem, wi::to_widest (compare_step_var), |
1278 | SIGNED, &overflow); | |
e913b5cd | 1279 | overall_overflow |= overflow; |
b3269f54 | 1280 | } |
fd757b76 | 1281 | else |
b3269f54 | 1282 | { |
1283 | /* (compare_bound - base) / compare_step */ | |
c311b856 | 1284 | tem = wi::sub (wi::to_widest (compare_var), |
1285 | wi::to_widest (compare_base), SIGNED, &overflow); | |
e913b5cd | 1286 | overall_overflow |= overflow; |
c311b856 | 1287 | compare_count = wi::div_trunc (tem, wi::to_widest (compare_step_var), |
1288 | SIGNED, &overflow); | |
e913b5cd | 1289 | overall_overflow |= overflow; |
b3269f54 | 1290 | } |
fd757b76 | 1291 | if (compare_code == LE_EXPR || compare_code == GE_EXPR) |
b3269f54 | 1292 | ++compare_count; |
fd757b76 | 1293 | if (loop_bound_code == LE_EXPR || loop_bound_code == GE_EXPR) |
b3269f54 | 1294 | ++loop_count; |
796b6678 | 1295 | if (wi::neg_p (compare_count)) |
e913b5cd | 1296 | compare_count = 0; |
796b6678 | 1297 | if (wi::neg_p (loop_count)) |
e913b5cd | 1298 | loop_count = 0; |
796b6678 | 1299 | if (loop_count == 0) |
fd757b76 | 1300 | probability = 0; |
796b6678 | 1301 | else if (wi::cmps (compare_count, loop_count) == 1) |
fd757b76 | 1302 | probability = REG_BR_PROB_BASE; |
1303 | else | |
b3269f54 | 1304 | { |
e913b5cd | 1305 | tem = compare_count * REG_BR_PROB_BASE; |
796b6678 | 1306 | tem = wi::udiv_trunc (tem, loop_count); |
b3269f54 | 1307 | probability = tem.to_uhwi (); |
1308 | } | |
1309 | ||
e913b5cd | 1310 | if (!overall_overflow) |
b3269f54 | 1311 | predict_edge (then_edge, PRED_LOOP_IV_COMPARE, probability); |
1312 | ||
fd757b76 | 1313 | return; |
1314 | } | |
1315 | ||
1316 | if (expr_coherent_p (loop_bound_var, compare_var)) | |
1317 | { | |
1318 | if ((loop_bound_code == LT_EXPR || loop_bound_code == LE_EXPR) | |
1319 | && (compare_code == LT_EXPR || compare_code == LE_EXPR)) | |
1320 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1321 | else if ((loop_bound_code == GT_EXPR || loop_bound_code == GE_EXPR) | |
1322 | && (compare_code == GT_EXPR || compare_code == GE_EXPR)) | |
1323 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1324 | else if (loop_bound_code == NE_EXPR) | |
1325 | { | |
1326 | /* If the loop backedge condition is "(i != bound)", we do | |
1327 | the comparison based on the step of IV: | |
1328 | * step < 0 : backedge condition is like (i > bound) | |
1329 | * step > 0 : backedge condition is like (i < bound) */ | |
1330 | gcc_assert (loop_bound_step != 0); | |
1331 | if (loop_bound_step > 0 | |
1332 | && (compare_code == LT_EXPR | |
1333 | || compare_code == LE_EXPR)) | |
1334 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1335 | else if (loop_bound_step < 0 | |
1336 | && (compare_code == GT_EXPR | |
1337 | || compare_code == GE_EXPR)) | |
1338 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1339 | else | |
1340 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1341 | } | |
1342 | else | |
1343 | /* The branch is predicted not-taken if loop_bound_code is | |
1344 | opposite with compare_code. */ | |
1345 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1346 | } | |
1347 | else if (expr_coherent_p (loop_iv_base_var, compare_var)) | |
1348 | { | |
1349 | /* For cases like: | |
1350 | for (i = s; i < h; i++) | |
1351 | if (i > s + 2) .... | |
1352 | The branch should be predicted taken. */ | |
1353 | if (loop_bound_step > 0 | |
1354 | && (compare_code == GT_EXPR || compare_code == GE_EXPR)) | |
1355 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1356 | else if (loop_bound_step < 0 | |
1357 | && (compare_code == LT_EXPR || compare_code == LE_EXPR)) | |
1358 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1359 | else | |
1360 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1361 | } | |
1362 | } | |
4ca17abf | 1363 | |
1364 | /* Predict for extra loop exits that will lead to EXIT_EDGE. The extra loop | |
1365 | exits are resulted from short-circuit conditions that will generate an | |
1366 | if_tmp. E.g.: | |
1367 | ||
1368 | if (foo() || global > 10) | |
1369 | break; | |
1370 | ||
1371 | This will be translated into: | |
1372 | ||
1373 | BB3: | |
1374 | loop header... | |
1375 | BB4: | |
1376 | if foo() goto BB6 else goto BB5 | |
1377 | BB5: | |
1378 | if global > 10 goto BB6 else goto BB7 | |
1379 | BB6: | |
1380 | goto BB7 | |
1381 | BB7: | |
1382 | iftmp = (PHI 0(BB5), 1(BB6)) | |
1383 | if iftmp == 1 goto BB8 else goto BB3 | |
1384 | BB8: | |
1385 | outside of the loop... | |
1386 | ||
1387 | The edge BB7->BB8 is loop exit because BB8 is outside of the loop. | |
1388 | From the dataflow, we can infer that BB4->BB6 and BB5->BB6 are also loop | |
1389 | exits. This function takes BB7->BB8 as input, and finds out the extra loop | |
1390 | exits to predict them using PRED_LOOP_EXIT. */ | |
1391 | ||
1392 | static void | |
1393 | predict_extra_loop_exits (edge exit_edge) | |
1394 | { | |
1395 | unsigned i; | |
1396 | bool check_value_one; | |
42acab1c | 1397 | gimple *lhs_def_stmt; |
1a91d914 | 1398 | gphi *phi_stmt; |
4ca17abf | 1399 | tree cmp_rhs, cmp_lhs; |
42acab1c | 1400 | gimple *last; |
1a91d914 | 1401 | gcond *cmp_stmt; |
4ca17abf | 1402 | |
1a91d914 | 1403 | last = last_stmt (exit_edge->src); |
1404 | if (!last) | |
1405 | return; | |
1406 | cmp_stmt = dyn_cast <gcond *> (last); | |
1407 | if (!cmp_stmt) | |
4ca17abf | 1408 | return; |
1a91d914 | 1409 | |
4ca17abf | 1410 | cmp_rhs = gimple_cond_rhs (cmp_stmt); |
1411 | cmp_lhs = gimple_cond_lhs (cmp_stmt); | |
1412 | if (!TREE_CONSTANT (cmp_rhs) | |
1413 | || !(integer_zerop (cmp_rhs) || integer_onep (cmp_rhs))) | |
1414 | return; | |
1415 | if (TREE_CODE (cmp_lhs) != SSA_NAME) | |
1416 | return; | |
1417 | ||
1418 | /* If check_value_one is true, only the phi_args with value '1' will lead | |
1419 | to loop exit. Otherwise, only the phi_args with value '0' will lead to | |
1420 | loop exit. */ | |
1421 | check_value_one = (((integer_onep (cmp_rhs)) | |
1422 | ^ (gimple_cond_code (cmp_stmt) == EQ_EXPR)) | |
1423 | ^ ((exit_edge->flags & EDGE_TRUE_VALUE) != 0)); | |
1424 | ||
1a91d914 | 1425 | lhs_def_stmt = SSA_NAME_DEF_STMT (cmp_lhs); |
1426 | if (!lhs_def_stmt) | |
1427 | return; | |
1428 | ||
1429 | phi_stmt = dyn_cast <gphi *> (lhs_def_stmt); | |
1430 | if (!phi_stmt) | |
4ca17abf | 1431 | return; |
1432 | ||
1433 | for (i = 0; i < gimple_phi_num_args (phi_stmt); i++) | |
1434 | { | |
1435 | edge e1; | |
1436 | edge_iterator ei; | |
1437 | tree val = gimple_phi_arg_def (phi_stmt, i); | |
1438 | edge e = gimple_phi_arg_edge (phi_stmt, i); | |
1439 | ||
1440 | if (!TREE_CONSTANT (val) || !(integer_zerop (val) || integer_onep (val))) | |
1441 | continue; | |
1442 | if ((check_value_one ^ integer_onep (val)) == 1) | |
1443 | continue; | |
1444 | if (EDGE_COUNT (e->src->succs) != 1) | |
1445 | { | |
1446 | predict_paths_leading_to_edge (e, PRED_LOOP_EXIT, NOT_TAKEN); | |
1447 | continue; | |
1448 | } | |
1449 | ||
1450 | FOR_EACH_EDGE (e1, ei, e->src->preds) | |
1451 | predict_paths_leading_to_edge (e1, PRED_LOOP_EXIT, NOT_TAKEN); | |
1452 | } | |
1453 | } | |
1454 | ||
7194de72 | 1455 | /* Predict edge probabilities by exploiting loop structure. */ |
1456 | ||
4ee9c684 | 1457 | static void |
7194de72 | 1458 | predict_loops (void) |
4ee9c684 | 1459 | { |
17519ba0 | 1460 | struct loop *loop; |
c12f2fcb | 1461 | |
7fcadf62 | 1462 | /* Try to predict out blocks in a loop that are not part of a |
1463 | natural loop. */ | |
f21d4d00 | 1464 | FOR_EACH_LOOP (loop, 0) |
59423b59 | 1465 | { |
7fb12188 | 1466 | basic_block bb, *bbs; |
749ea85f | 1467 | unsigned j, n_exits; |
f1f41a6c | 1468 | vec<edge> exits; |
3b0b2309 | 1469 | struct tree_niter_desc niter_desc; |
749ea85f | 1470 | edge ex; |
fd757b76 | 1471 | struct nb_iter_bound *nb_iter; |
1472 | enum tree_code loop_bound_code = ERROR_MARK; | |
b3269f54 | 1473 | tree loop_bound_step = NULL; |
fd757b76 | 1474 | tree loop_bound_var = NULL; |
1475 | tree loop_iv_base = NULL; | |
1a91d914 | 1476 | gcond *stmt = NULL; |
59423b59 | 1477 | |
749ea85f | 1478 | exits = get_loop_exit_edges (loop); |
f1f41a6c | 1479 | n_exits = exits.length (); |
5d865361 | 1480 | if (!n_exits) |
1481 | { | |
f1f41a6c | 1482 | exits.release (); |
5d865361 | 1483 | continue; |
1484 | } | |
ba38e12b | 1485 | |
f1f41a6c | 1486 | FOR_EACH_VEC_ELT (exits, j, ex) |
d27b0b64 | 1487 | { |
3b0b2309 | 1488 | tree niter = NULL; |
d500fef3 | 1489 | HOST_WIDE_INT nitercst; |
1490 | int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS); | |
1491 | int probability; | |
1492 | enum br_predictor predictor; | |
d27b0b64 | 1493 | |
4ca17abf | 1494 | predict_extra_loop_exits (ex); |
1495 | ||
3f78e715 | 1496 | if (number_of_iterations_exit (loop, ex, &niter_desc, false, false)) |
3b0b2309 | 1497 | niter = niter_desc.niter; |
1498 | if (!niter || TREE_CODE (niter_desc.niter) != INTEGER_CST) | |
749ea85f | 1499 | niter = loop_niter_by_eval (loop, ex); |
d27b0b64 | 1500 | |
3b0b2309 | 1501 | if (TREE_CODE (niter) == INTEGER_CST) |
1502 | { | |
e913b5cd | 1503 | if (tree_fits_uhwi_p (niter) |
ed60f27f | 1504 | && max |
1505 | && compare_tree_int (niter, max - 1) == -1) | |
e913b5cd | 1506 | nitercst = tree_to_uhwi (niter) + 1; |
3b0b2309 | 1507 | else |
d500fef3 | 1508 | nitercst = max; |
1509 | predictor = PRED_LOOP_ITERATIONS; | |
1510 | } | |
1511 | /* If we have just one exit and we can derive some information about | |
1512 | the number of iterations of the loop from the statements inside | |
1513 | the loop, use it to predict this exit. */ | |
1514 | else if (n_exits == 1) | |
1515 | { | |
fee017b3 | 1516 | nitercst = estimated_stmt_executions_int (loop); |
d500fef3 | 1517 | if (nitercst < 0) |
1518 | continue; | |
1519 | if (nitercst > max) | |
1520 | nitercst = max; | |
d27b0b64 | 1521 | |
d500fef3 | 1522 | predictor = PRED_LOOP_ITERATIONS_GUESSED; |
3b0b2309 | 1523 | } |
d500fef3 | 1524 | else |
1525 | continue; | |
1526 | ||
ed60f27f | 1527 | /* If the prediction for number of iterations is zero, do not |
1528 | predict the exit edges. */ | |
1529 | if (nitercst == 0) | |
1530 | continue; | |
1531 | ||
d500fef3 | 1532 | probability = ((REG_BR_PROB_BASE + nitercst / 2) / nitercst); |
1533 | predict_edge (ex, predictor, probability); | |
d27b0b64 | 1534 | } |
f1f41a6c | 1535 | exits.release (); |
862be747 | 1536 | |
fd757b76 | 1537 | /* Find information about loop bound variables. */ |
1538 | for (nb_iter = loop->bounds; nb_iter; | |
1539 | nb_iter = nb_iter->next) | |
1540 | if (nb_iter->stmt | |
1541 | && gimple_code (nb_iter->stmt) == GIMPLE_COND) | |
1542 | { | |
1a91d914 | 1543 | stmt = as_a <gcond *> (nb_iter->stmt); |
fd757b76 | 1544 | break; |
1545 | } | |
1546 | if (!stmt && last_stmt (loop->header) | |
1547 | && gimple_code (last_stmt (loop->header)) == GIMPLE_COND) | |
1a91d914 | 1548 | stmt = as_a <gcond *> (last_stmt (loop->header)); |
fd757b76 | 1549 | if (stmt) |
1550 | is_comparison_with_loop_invariant_p (stmt, loop, | |
1551 | &loop_bound_var, | |
1552 | &loop_bound_code, | |
1553 | &loop_bound_step, | |
1554 | &loop_iv_base); | |
1555 | ||
7fb12188 | 1556 | bbs = get_loop_body (loop); |
4ee9c684 | 1557 | |
7fb12188 | 1558 | for (j = 0; j < loop->num_nodes; j++) |
1559 | { | |
1560 | int header_found = 0; | |
1561 | edge e; | |
cd665a06 | 1562 | edge_iterator ei; |
7fb12188 | 1563 | |
1564 | bb = bbs[j]; | |
e6751e9a | 1565 | |
cd0fe062 | 1566 | /* Bypass loop heuristics on continue statement. These |
1567 | statements construct loops via "non-loop" constructs | |
1568 | in the source language and are better to be handled | |
1569 | separately. */ | |
3b0b2309 | 1570 | if (predicted_by_p (bb, PRED_CONTINUE)) |
cd0fe062 | 1571 | continue; |
1572 | ||
7fb12188 | 1573 | /* Loop branch heuristics - predict an edge back to a |
1574 | loop's head as taken. */ | |
c6356c17 | 1575 | if (bb == loop->latch) |
1576 | { | |
1577 | e = find_edge (loop->latch, loop->header); | |
1578 | if (e) | |
1579 | { | |
1580 | header_found = 1; | |
1581 | predict_edge_def (e, PRED_LOOP_BRANCH, TAKEN); | |
1582 | } | |
1583 | } | |
e6751e9a | 1584 | |
7fb12188 | 1585 | /* Loop exit heuristics - predict an edge exiting the loop if the |
41a6f238 | 1586 | conditional has no loop header successors as not taken. */ |
d500fef3 | 1587 | if (!header_found |
1588 | /* If we already used more reliable loop exit predictors, do not | |
1589 | bother with PRED_LOOP_EXIT. */ | |
1590 | && !predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED) | |
1591 | && !predicted_by_p (bb, PRED_LOOP_ITERATIONS)) | |
b41438e5 | 1592 | { |
1593 | /* For loop with many exits we don't want to predict all exits | |
1594 | with the pretty large probability, because if all exits are | |
1595 | considered in row, the loop would be predicted to iterate | |
1596 | almost never. The code to divide probability by number of | |
1597 | exits is very rough. It should compute the number of exits | |
1598 | taken in each patch through function (not the overall number | |
1599 | of exits that might be a lot higher for loops with wide switch | |
1600 | statements in them) and compute n-th square root. | |
1601 | ||
1602 | We limit the minimal probability by 2% to avoid | |
1603 | EDGE_PROBABILITY_RELIABLE from trusting the branch prediction | |
1604 | as this was causing regression in perl benchmark containing such | |
1605 | a wide loop. */ | |
48e1416a | 1606 | |
b41438e5 | 1607 | int probability = ((REG_BR_PROB_BASE |
1608 | - predictor_info [(int) PRED_LOOP_EXIT].hitrate) | |
1609 | / n_exits); | |
1610 | if (probability < HITRATE (2)) | |
1611 | probability = HITRATE (2); | |
1612 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1613 | if (e->dest->index < NUM_FIXED_BLOCKS | |
1614 | || !flow_bb_inside_loop_p (loop, e->dest)) | |
1615 | predict_edge (e, PRED_LOOP_EXIT, probability); | |
1616 | } | |
fd757b76 | 1617 | if (loop_bound_var) |
1618 | predict_iv_comparison (loop, bb, loop_bound_var, loop_iv_base, | |
1619 | loop_bound_code, | |
e913b5cd | 1620 | tree_to_shwi (loop_bound_step)); |
7fb12188 | 1621 | } |
48e1416a | 1622 | |
21dda4ee | 1623 | /* Free basic blocks from get_loop_body. */ |
dcd8fd01 | 1624 | free (bbs); |
59423b59 | 1625 | } |
4ee9c684 | 1626 | } |
1627 | ||
83c8a977 | 1628 | /* Attempt to predict probabilities of BB outgoing edges using local |
1629 | properties. */ | |
1630 | static void | |
1631 | bb_estimate_probability_locally (basic_block bb) | |
1632 | { | |
ee5f6585 | 1633 | rtx_insn *last_insn = BB_END (bb); |
83c8a977 | 1634 | rtx cond; |
1635 | ||
1636 | if (! can_predict_insn_p (last_insn)) | |
1637 | return; | |
1638 | cond = get_condition (last_insn, NULL, false, false); | |
1639 | if (! cond) | |
1640 | return; | |
1641 | ||
1642 | /* Try "pointer heuristic." | |
1643 | A comparison ptr == 0 is predicted as false. | |
1644 | Similarly, a comparison ptr1 == ptr2 is predicted as false. */ | |
1645 | if (COMPARISON_P (cond) | |
1646 | && ((REG_P (XEXP (cond, 0)) && REG_POINTER (XEXP (cond, 0))) | |
1647 | || (REG_P (XEXP (cond, 1)) && REG_POINTER (XEXP (cond, 1))))) | |
1648 | { | |
1649 | if (GET_CODE (cond) == EQ) | |
1650 | predict_insn_def (last_insn, PRED_POINTER, NOT_TAKEN); | |
1651 | else if (GET_CODE (cond) == NE) | |
1652 | predict_insn_def (last_insn, PRED_POINTER, TAKEN); | |
1653 | } | |
1654 | else | |
1655 | ||
1656 | /* Try "opcode heuristic." | |
1657 | EQ tests are usually false and NE tests are usually true. Also, | |
1658 | most quantities are positive, so we can make the appropriate guesses | |
1659 | about signed comparisons against zero. */ | |
1660 | switch (GET_CODE (cond)) | |
1661 | { | |
1662 | case CONST_INT: | |
1663 | /* Unconditional branch. */ | |
1664 | predict_insn_def (last_insn, PRED_UNCONDITIONAL, | |
1665 | cond == const0_rtx ? NOT_TAKEN : TAKEN); | |
1666 | break; | |
1667 | ||
1668 | case EQ: | |
1669 | case UNEQ: | |
1670 | /* Floating point comparisons appears to behave in a very | |
1671 | unpredictable way because of special role of = tests in | |
1672 | FP code. */ | |
1673 | if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0)))) | |
1674 | ; | |
1675 | /* Comparisons with 0 are often used for booleans and there is | |
1676 | nothing useful to predict about them. */ | |
1677 | else if (XEXP (cond, 1) == const0_rtx | |
1678 | || XEXP (cond, 0) == const0_rtx) | |
1679 | ; | |
1680 | else | |
1681 | predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, NOT_TAKEN); | |
1682 | break; | |
1683 | ||
1684 | case NE: | |
1685 | case LTGT: | |
1686 | /* Floating point comparisons appears to behave in a very | |
1687 | unpredictable way because of special role of = tests in | |
1688 | FP code. */ | |
1689 | if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0)))) | |
1690 | ; | |
1691 | /* Comparisons with 0 are often used for booleans and there is | |
1692 | nothing useful to predict about them. */ | |
1693 | else if (XEXP (cond, 1) == const0_rtx | |
1694 | || XEXP (cond, 0) == const0_rtx) | |
1695 | ; | |
1696 | else | |
1697 | predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, TAKEN); | |
1698 | break; | |
1699 | ||
1700 | case ORDERED: | |
1701 | predict_insn_def (last_insn, PRED_FPOPCODE, TAKEN); | |
1702 | break; | |
1703 | ||
1704 | case UNORDERED: | |
1705 | predict_insn_def (last_insn, PRED_FPOPCODE, NOT_TAKEN); | |
1706 | break; | |
1707 | ||
1708 | case LE: | |
1709 | case LT: | |
1710 | if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx | |
1711 | || XEXP (cond, 1) == constm1_rtx) | |
1712 | predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, NOT_TAKEN); | |
1713 | break; | |
1714 | ||
1715 | case GE: | |
1716 | case GT: | |
1717 | if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx | |
1718 | || XEXP (cond, 1) == constm1_rtx) | |
1719 | predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, TAKEN); | |
1720 | break; | |
1721 | ||
1722 | default: | |
1723 | break; | |
1724 | } | |
1725 | } | |
1726 | ||
7edd21a5 | 1727 | /* Set edge->probability for each successor edge of BB. */ |
83c8a977 | 1728 | void |
1729 | guess_outgoing_edge_probabilities (basic_block bb) | |
1730 | { | |
1731 | bb_estimate_probability_locally (bb); | |
1732 | combine_predictions_for_insn (BB_END (bb), bb); | |
1733 | } | |
4ee9c684 | 1734 | \f |
c83059be | 1735 | static tree expr_expected_value (tree, bitmap, enum br_predictor *predictor); |
75a70cf9 | 1736 | |
1737 | /* Helper function for expr_expected_value. */ | |
42975b1f | 1738 | |
1739 | static tree | |
2380e91e | 1740 | expr_expected_value_1 (tree type, tree op0, enum tree_code code, |
c83059be | 1741 | tree op1, bitmap visited, enum br_predictor *predictor) |
42975b1f | 1742 | { |
42acab1c | 1743 | gimple *def; |
75a70cf9 | 1744 | |
c83059be | 1745 | if (predictor) |
1746 | *predictor = PRED_UNCONDITIONAL; | |
1747 | ||
75a70cf9 | 1748 | if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS) |
42975b1f | 1749 | { |
75a70cf9 | 1750 | if (TREE_CONSTANT (op0)) |
1751 | return op0; | |
1752 | ||
1753 | if (code != SSA_NAME) | |
1754 | return NULL_TREE; | |
1755 | ||
1756 | def = SSA_NAME_DEF_STMT (op0); | |
42975b1f | 1757 | |
1758 | /* If we were already here, break the infinite cycle. */ | |
6ef9bbe0 | 1759 | if (!bitmap_set_bit (visited, SSA_NAME_VERSION (op0))) |
42975b1f | 1760 | return NULL; |
42975b1f | 1761 | |
75a70cf9 | 1762 | if (gimple_code (def) == GIMPLE_PHI) |
42975b1f | 1763 | { |
1764 | /* All the arguments of the PHI node must have the same constant | |
1765 | length. */ | |
75a70cf9 | 1766 | int i, n = gimple_phi_num_args (def); |
42975b1f | 1767 | tree val = NULL, new_val; |
4ee9c684 | 1768 | |
75a70cf9 | 1769 | for (i = 0; i < n; i++) |
42975b1f | 1770 | { |
1771 | tree arg = PHI_ARG_DEF (def, i); | |
c83059be | 1772 | enum br_predictor predictor2; |
42975b1f | 1773 | |
1774 | /* If this PHI has itself as an argument, we cannot | |
1775 | determine the string length of this argument. However, | |
86481e89 | 1776 | if we can find an expected constant value for the other |
42975b1f | 1777 | PHI args then we can still be sure that this is |
1778 | likely a constant. So be optimistic and just | |
1779 | continue with the next argument. */ | |
1780 | if (arg == PHI_RESULT (def)) | |
1781 | continue; | |
1782 | ||
c83059be | 1783 | new_val = expr_expected_value (arg, visited, &predictor2); |
1784 | ||
1785 | /* It is difficult to combine value predictors. Simply assume | |
1786 | that later predictor is weaker and take its prediction. */ | |
1787 | if (predictor && *predictor < predictor2) | |
1788 | *predictor = predictor2; | |
42975b1f | 1789 | if (!new_val) |
1790 | return NULL; | |
1791 | if (!val) | |
1792 | val = new_val; | |
1793 | else if (!operand_equal_p (val, new_val, false)) | |
1794 | return NULL; | |
1795 | } | |
1796 | return val; | |
1797 | } | |
75a70cf9 | 1798 | if (is_gimple_assign (def)) |
42975b1f | 1799 | { |
75a70cf9 | 1800 | if (gimple_assign_lhs (def) != op0) |
1801 | return NULL; | |
42975b1f | 1802 | |
75a70cf9 | 1803 | return expr_expected_value_1 (TREE_TYPE (gimple_assign_lhs (def)), |
1804 | gimple_assign_rhs1 (def), | |
1805 | gimple_assign_rhs_code (def), | |
1806 | gimple_assign_rhs2 (def), | |
c83059be | 1807 | visited, predictor); |
75a70cf9 | 1808 | } |
1809 | ||
1810 | if (is_gimple_call (def)) | |
1811 | { | |
1812 | tree decl = gimple_call_fndecl (def); | |
1813 | if (!decl) | |
c83059be | 1814 | { |
1815 | if (gimple_call_internal_p (def) | |
1816 | && gimple_call_internal_fn (def) == IFN_BUILTIN_EXPECT) | |
1817 | { | |
1818 | gcc_assert (gimple_call_num_args (def) == 3); | |
1819 | tree val = gimple_call_arg (def, 0); | |
1820 | if (TREE_CONSTANT (val)) | |
1821 | return val; | |
1822 | if (predictor) | |
1823 | { | |
c83059be | 1824 | tree val2 = gimple_call_arg (def, 2); |
1825 | gcc_assert (TREE_CODE (val2) == INTEGER_CST | |
1826 | && tree_fits_uhwi_p (val2) | |
1827 | && tree_to_uhwi (val2) < END_PREDICTORS); | |
1828 | *predictor = (enum br_predictor) tree_to_uhwi (val2); | |
1829 | } | |
1830 | return gimple_call_arg (def, 1); | |
1831 | } | |
1832 | return NULL; | |
1833 | } | |
2380e91e | 1834 | if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL) |
1835 | switch (DECL_FUNCTION_CODE (decl)) | |
1836 | { | |
1837 | case BUILT_IN_EXPECT: | |
1838 | { | |
1839 | tree val; | |
1840 | if (gimple_call_num_args (def) != 2) | |
1841 | return NULL; | |
1842 | val = gimple_call_arg (def, 0); | |
1843 | if (TREE_CONSTANT (val)) | |
1844 | return val; | |
c83059be | 1845 | if (predictor) |
1846 | *predictor = PRED_BUILTIN_EXPECT; | |
2380e91e | 1847 | return gimple_call_arg (def, 1); |
1848 | } | |
75a70cf9 | 1849 | |
2380e91e | 1850 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_N: |
1851 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_1: | |
1852 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2: | |
1853 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4: | |
1854 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8: | |
1855 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16: | |
1856 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE: | |
1857 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_N: | |
1858 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1: | |
1859 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2: | |
1860 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4: | |
1861 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8: | |
1862 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16: | |
1863 | /* Assume that any given atomic operation has low contention, | |
1864 | and thus the compare-and-swap operation succeeds. */ | |
c83059be | 1865 | if (predictor) |
1866 | *predictor = PRED_COMPARE_AND_SWAP; | |
2380e91e | 1867 | return boolean_true_node; |
5213d6c9 | 1868 | default: |
1869 | break; | |
75a70cf9 | 1870 | } |
42975b1f | 1871 | } |
75a70cf9 | 1872 | |
1873 | return NULL; | |
42975b1f | 1874 | } |
75a70cf9 | 1875 | |
1876 | if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS) | |
42975b1f | 1877 | { |
75a70cf9 | 1878 | tree res; |
c83059be | 1879 | enum br_predictor predictor2; |
1880 | op0 = expr_expected_value (op0, visited, predictor); | |
42975b1f | 1881 | if (!op0) |
1882 | return NULL; | |
c83059be | 1883 | op1 = expr_expected_value (op1, visited, &predictor2); |
1884 | if (predictor && *predictor < predictor2) | |
1885 | *predictor = predictor2; | |
42975b1f | 1886 | if (!op1) |
1887 | return NULL; | |
75a70cf9 | 1888 | res = fold_build2 (code, type, op0, op1); |
42975b1f | 1889 | if (TREE_CONSTANT (res)) |
1890 | return res; | |
1891 | return NULL; | |
1892 | } | |
75a70cf9 | 1893 | if (get_gimple_rhs_class (code) == GIMPLE_UNARY_RHS) |
42975b1f | 1894 | { |
75a70cf9 | 1895 | tree res; |
c83059be | 1896 | op0 = expr_expected_value (op0, visited, predictor); |
42975b1f | 1897 | if (!op0) |
1898 | return NULL; | |
75a70cf9 | 1899 | res = fold_build1 (code, type, op0); |
42975b1f | 1900 | if (TREE_CONSTANT (res)) |
1901 | return res; | |
1902 | return NULL; | |
1903 | } | |
1904 | return NULL; | |
1905 | } | |
75a70cf9 | 1906 | |
48e1416a | 1907 | /* Return constant EXPR will likely have at execution time, NULL if unknown. |
75a70cf9 | 1908 | The function is used by builtin_expect branch predictor so the evidence |
1909 | must come from this construct and additional possible constant folding. | |
48e1416a | 1910 | |
75a70cf9 | 1911 | We may want to implement more involved value guess (such as value range |
1912 | propagation based prediction), but such tricks shall go to new | |
1913 | implementation. */ | |
1914 | ||
1915 | static tree | |
c83059be | 1916 | expr_expected_value (tree expr, bitmap visited, |
1917 | enum br_predictor *predictor) | |
75a70cf9 | 1918 | { |
1919 | enum tree_code code; | |
1920 | tree op0, op1; | |
1921 | ||
1922 | if (TREE_CONSTANT (expr)) | |
c83059be | 1923 | { |
1924 | if (predictor) | |
1925 | *predictor = PRED_UNCONDITIONAL; | |
1926 | return expr; | |
1927 | } | |
75a70cf9 | 1928 | |
1929 | extract_ops_from_tree (expr, &code, &op0, &op1); | |
1930 | return expr_expected_value_1 (TREE_TYPE (expr), | |
c83059be | 1931 | op0, code, op1, visited, predictor); |
75a70cf9 | 1932 | } |
42975b1f | 1933 | \f |
4ee9c684 | 1934 | /* Predict using opcode of the last statement in basic block. */ |
1935 | static void | |
1936 | tree_predict_by_opcode (basic_block bb) | |
1937 | { | |
42acab1c | 1938 | gimple *stmt = last_stmt (bb); |
4ee9c684 | 1939 | edge then_edge; |
75a70cf9 | 1940 | tree op0, op1; |
4ee9c684 | 1941 | tree type; |
42975b1f | 1942 | tree val; |
75a70cf9 | 1943 | enum tree_code cmp; |
42975b1f | 1944 | bitmap visited; |
cd665a06 | 1945 | edge_iterator ei; |
c83059be | 1946 | enum br_predictor predictor; |
4ee9c684 | 1947 | |
75a70cf9 | 1948 | if (!stmt || gimple_code (stmt) != GIMPLE_COND) |
4ee9c684 | 1949 | return; |
cd665a06 | 1950 | FOR_EACH_EDGE (then_edge, ei, bb->succs) |
4ee9c684 | 1951 | if (then_edge->flags & EDGE_TRUE_VALUE) |
cd665a06 | 1952 | break; |
75a70cf9 | 1953 | op0 = gimple_cond_lhs (stmt); |
1954 | op1 = gimple_cond_rhs (stmt); | |
1955 | cmp = gimple_cond_code (stmt); | |
4ee9c684 | 1956 | type = TREE_TYPE (op0); |
27335ffd | 1957 | visited = BITMAP_ALLOC (NULL); |
c83059be | 1958 | val = expr_expected_value_1 (boolean_type_node, op0, cmp, op1, visited, |
1959 | &predictor); | |
27335ffd | 1960 | BITMAP_FREE (visited); |
c83059be | 1961 | if (val && TREE_CODE (val) == INTEGER_CST) |
42975b1f | 1962 | { |
c83059be | 1963 | if (predictor == PRED_BUILTIN_EXPECT) |
1964 | { | |
1965 | int percent = PARAM_VALUE (BUILTIN_EXPECT_PROBABILITY); | |
21853731 | 1966 | |
c83059be | 1967 | gcc_assert (percent >= 0 && percent <= 100); |
1968 | if (integer_zerop (val)) | |
1969 | percent = 100 - percent; | |
1970 | predict_edge (then_edge, PRED_BUILTIN_EXPECT, HITRATE (percent)); | |
1971 | } | |
1972 | else | |
1973 | predict_edge (then_edge, predictor, | |
1974 | integer_zerop (val) ? NOT_TAKEN : TAKEN); | |
42975b1f | 1975 | } |
4ee9c684 | 1976 | /* Try "pointer heuristic." |
1977 | A comparison ptr == 0 is predicted as false. | |
1978 | Similarly, a comparison ptr1 == ptr2 is predicted as false. */ | |
1979 | if (POINTER_TYPE_P (type)) | |
1980 | { | |
75a70cf9 | 1981 | if (cmp == EQ_EXPR) |
4ee9c684 | 1982 | predict_edge_def (then_edge, PRED_TREE_POINTER, NOT_TAKEN); |
75a70cf9 | 1983 | else if (cmp == NE_EXPR) |
4ee9c684 | 1984 | predict_edge_def (then_edge, PRED_TREE_POINTER, TAKEN); |
1985 | } | |
1986 | else | |
1987 | ||
1988 | /* Try "opcode heuristic." | |
1989 | EQ tests are usually false and NE tests are usually true. Also, | |
1990 | most quantities are positive, so we can make the appropriate guesses | |
1991 | about signed comparisons against zero. */ | |
75a70cf9 | 1992 | switch (cmp) |
4ee9c684 | 1993 | { |
1994 | case EQ_EXPR: | |
1995 | case UNEQ_EXPR: | |
1996 | /* Floating point comparisons appears to behave in a very | |
1997 | unpredictable way because of special role of = tests in | |
1998 | FP code. */ | |
1999 | if (FLOAT_TYPE_P (type)) | |
2000 | ; | |
2001 | /* Comparisons with 0 are often used for booleans and there is | |
2002 | nothing useful to predict about them. */ | |
75a70cf9 | 2003 | else if (integer_zerop (op0) || integer_zerop (op1)) |
4ee9c684 | 2004 | ; |
2005 | else | |
2006 | predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, NOT_TAKEN); | |
2007 | break; | |
2008 | ||
2009 | case NE_EXPR: | |
318a728f | 2010 | case LTGT_EXPR: |
4ee9c684 | 2011 | /* Floating point comparisons appears to behave in a very |
2012 | unpredictable way because of special role of = tests in | |
2013 | FP code. */ | |
2014 | if (FLOAT_TYPE_P (type)) | |
2015 | ; | |
2016 | /* Comparisons with 0 are often used for booleans and there is | |
2017 | nothing useful to predict about them. */ | |
2018 | else if (integer_zerop (op0) | |
75a70cf9 | 2019 | || integer_zerop (op1)) |
4ee9c684 | 2020 | ; |
2021 | else | |
2022 | predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, TAKEN); | |
2023 | break; | |
2024 | ||
2025 | case ORDERED_EXPR: | |
2026 | predict_edge_def (then_edge, PRED_TREE_FPOPCODE, TAKEN); | |
2027 | break; | |
2028 | ||
2029 | case UNORDERED_EXPR: | |
2030 | predict_edge_def (then_edge, PRED_TREE_FPOPCODE, NOT_TAKEN); | |
2031 | break; | |
2032 | ||
2033 | case LE_EXPR: | |
2034 | case LT_EXPR: | |
75a70cf9 | 2035 | if (integer_zerop (op1) |
2036 | || integer_onep (op1) | |
2037 | || integer_all_onesp (op1) | |
2038 | || real_zerop (op1) | |
2039 | || real_onep (op1) | |
2040 | || real_minus_onep (op1)) | |
4ee9c684 | 2041 | predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, NOT_TAKEN); |
2042 | break; | |
2043 | ||
2044 | case GE_EXPR: | |
2045 | case GT_EXPR: | |
75a70cf9 | 2046 | if (integer_zerop (op1) |
2047 | || integer_onep (op1) | |
2048 | || integer_all_onesp (op1) | |
2049 | || real_zerop (op1) | |
2050 | || real_onep (op1) | |
2051 | || real_minus_onep (op1)) | |
4ee9c684 | 2052 | predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, TAKEN); |
2053 | break; | |
2054 | ||
2055 | default: | |
2056 | break; | |
2057 | } | |
2058 | } | |
2059 | ||
f816ec49 | 2060 | /* Try to guess whether the value of return means error code. */ |
75a70cf9 | 2061 | |
f816ec49 | 2062 | static enum br_predictor |
2063 | return_prediction (tree val, enum prediction *prediction) | |
2064 | { | |
2065 | /* VOID. */ | |
2066 | if (!val) | |
2067 | return PRED_NO_PREDICTION; | |
2068 | /* Different heuristics for pointers and scalars. */ | |
2069 | if (POINTER_TYPE_P (TREE_TYPE (val))) | |
2070 | { | |
2071 | /* NULL is usually not returned. */ | |
2072 | if (integer_zerop (val)) | |
2073 | { | |
2074 | *prediction = NOT_TAKEN; | |
2075 | return PRED_NULL_RETURN; | |
2076 | } | |
2077 | } | |
2078 | else if (INTEGRAL_TYPE_P (TREE_TYPE (val))) | |
2079 | { | |
2080 | /* Negative return values are often used to indicate | |
2081 | errors. */ | |
2082 | if (TREE_CODE (val) == INTEGER_CST | |
2083 | && tree_int_cst_sgn (val) < 0) | |
2084 | { | |
2085 | *prediction = NOT_TAKEN; | |
2086 | return PRED_NEGATIVE_RETURN; | |
2087 | } | |
2088 | /* Constant return values seems to be commonly taken. | |
2089 | Zero/one often represent booleans so exclude them from the | |
2090 | heuristics. */ | |
2091 | if (TREE_CONSTANT (val) | |
2092 | && (!integer_zerop (val) && !integer_onep (val))) | |
2093 | { | |
2094 | *prediction = TAKEN; | |
4a4e4487 | 2095 | return PRED_CONST_RETURN; |
f816ec49 | 2096 | } |
2097 | } | |
2098 | return PRED_NO_PREDICTION; | |
2099 | } | |
2100 | ||
2101 | /* Find the basic block with return expression and look up for possible | |
2102 | return value trying to apply RETURN_PREDICTION heuristics. */ | |
2103 | static void | |
d704ea82 | 2104 | apply_return_prediction (void) |
f816ec49 | 2105 | { |
1a91d914 | 2106 | greturn *return_stmt = NULL; |
f816ec49 | 2107 | tree return_val; |
2108 | edge e; | |
1a91d914 | 2109 | gphi *phi; |
f816ec49 | 2110 | int phi_num_args, i; |
2111 | enum br_predictor pred; | |
2112 | enum prediction direction; | |
cd665a06 | 2113 | edge_iterator ei; |
f816ec49 | 2114 | |
34154e27 | 2115 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) |
f816ec49 | 2116 | { |
42acab1c | 2117 | gimple *last = last_stmt (e->src); |
1a91d914 | 2118 | if (last |
2119 | && gimple_code (last) == GIMPLE_RETURN) | |
2120 | { | |
2121 | return_stmt = as_a <greturn *> (last); | |
2122 | break; | |
2123 | } | |
f816ec49 | 2124 | } |
2125 | if (!e) | |
2126 | return; | |
75a70cf9 | 2127 | return_val = gimple_return_retval (return_stmt); |
f816ec49 | 2128 | if (!return_val) |
2129 | return; | |
f816ec49 | 2130 | if (TREE_CODE (return_val) != SSA_NAME |
2131 | || !SSA_NAME_DEF_STMT (return_val) | |
75a70cf9 | 2132 | || gimple_code (SSA_NAME_DEF_STMT (return_val)) != GIMPLE_PHI) |
f816ec49 | 2133 | return; |
1a91d914 | 2134 | phi = as_a <gphi *> (SSA_NAME_DEF_STMT (return_val)); |
75a70cf9 | 2135 | phi_num_args = gimple_phi_num_args (phi); |
f816ec49 | 2136 | pred = return_prediction (PHI_ARG_DEF (phi, 0), &direction); |
2137 | ||
2138 | /* Avoid the degenerate case where all return values form the function | |
2139 | belongs to same category (ie they are all positive constants) | |
2140 | so we can hardly say something about them. */ | |
2141 | for (i = 1; i < phi_num_args; i++) | |
2142 | if (pred != return_prediction (PHI_ARG_DEF (phi, i), &direction)) | |
2143 | break; | |
2144 | if (i != phi_num_args) | |
2145 | for (i = 0; i < phi_num_args; i++) | |
2146 | { | |
2147 | pred = return_prediction (PHI_ARG_DEF (phi, i), &direction); | |
2148 | if (pred != PRED_NO_PREDICTION) | |
5707768a | 2149 | predict_paths_leading_to_edge (gimple_phi_arg_edge (phi, i), pred, |
2150 | direction); | |
f816ec49 | 2151 | } |
2152 | } | |
2153 | ||
2154 | /* Look for basic block that contains unlikely to happen events | |
2155 | (such as noreturn calls) and mark all paths leading to execution | |
2156 | of this basic blocks as unlikely. */ | |
2157 | ||
2158 | static void | |
2159 | tree_bb_level_predictions (void) | |
2160 | { | |
2161 | basic_block bb; | |
9f694a82 | 2162 | bool has_return_edges = false; |
2163 | edge e; | |
2164 | edge_iterator ei; | |
2165 | ||
34154e27 | 2166 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) |
9f694a82 | 2167 | if (!(e->flags & (EDGE_ABNORMAL | EDGE_FAKE | EDGE_EH))) |
2168 | { | |
2169 | has_return_edges = true; | |
2170 | break; | |
2171 | } | |
f816ec49 | 2172 | |
d704ea82 | 2173 | apply_return_prediction (); |
f816ec49 | 2174 | |
fc00614f | 2175 | FOR_EACH_BB_FN (bb, cfun) |
f816ec49 | 2176 | { |
75a70cf9 | 2177 | gimple_stmt_iterator gsi; |
f816ec49 | 2178 | |
1add270f | 2179 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
f816ec49 | 2180 | { |
42acab1c | 2181 | gimple *stmt = gsi_stmt (gsi); |
5de92639 | 2182 | tree decl; |
3ed4a4a1 | 2183 | |
75a70cf9 | 2184 | if (is_gimple_call (stmt)) |
f816ec49 | 2185 | { |
9f694a82 | 2186 | if ((gimple_call_flags (stmt) & ECF_NORETURN) |
2187 | && has_return_edges) | |
75a70cf9 | 2188 | predict_paths_leading_to (bb, PRED_NORETURN, |
2189 | NOT_TAKEN); | |
2190 | decl = gimple_call_fndecl (stmt); | |
2191 | if (decl | |
2192 | && lookup_attribute ("cold", | |
2193 | DECL_ATTRIBUTES (decl))) | |
2194 | predict_paths_leading_to (bb, PRED_COLD_FUNCTION, | |
2195 | NOT_TAKEN); | |
f816ec49 | 2196 | } |
75a70cf9 | 2197 | else if (gimple_code (stmt) == GIMPLE_PREDICT) |
2198 | { | |
2199 | predict_paths_leading_to (bb, gimple_predict_predictor (stmt), | |
2200 | gimple_predict_outcome (stmt)); | |
1add270f | 2201 | /* Keep GIMPLE_PREDICT around so early inlining will propagate |
2202 | hints to callers. */ | |
75a70cf9 | 2203 | } |
f816ec49 | 2204 | } |
2205 | } | |
f816ec49 | 2206 | } |
2207 | ||
06ecf488 | 2208 | /* Callback for hash_map::traverse, asserts that the pointer map is |
b3723726 | 2209 | empty. */ |
2210 | ||
06ecf488 | 2211 | bool |
2212 | assert_is_empty (const_basic_block const &, edge_prediction *const &value, | |
2213 | void *) | |
b3723726 | 2214 | { |
06ecf488 | 2215 | gcc_assert (!value); |
b3723726 | 2216 | return false; |
2217 | } | |
b3723726 | 2218 | |
675d86b2 | 2219 | /* Predict branch probabilities and estimate profile for basic block BB. */ |
2220 | ||
2221 | static void | |
2222 | tree_estimate_probability_bb (basic_block bb) | |
2223 | { | |
2224 | edge e; | |
2225 | edge_iterator ei; | |
42acab1c | 2226 | gimple *last; |
675d86b2 | 2227 | |
2228 | FOR_EACH_EDGE (e, ei, bb->succs) | |
2229 | { | |
758a38ab | 2230 | /* Predict edges to user labels with attributes. */ |
34154e27 | 2231 | if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)) |
758a38ab | 2232 | { |
2233 | gimple_stmt_iterator gi; | |
2234 | for (gi = gsi_start_bb (e->dest); !gsi_end_p (gi); gsi_next (&gi)) | |
2235 | { | |
1a91d914 | 2236 | glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gi)); |
758a38ab | 2237 | tree decl; |
2238 | ||
1a91d914 | 2239 | if (!label_stmt) |
758a38ab | 2240 | break; |
1a91d914 | 2241 | decl = gimple_label_label (label_stmt); |
758a38ab | 2242 | if (DECL_ARTIFICIAL (decl)) |
2243 | continue; | |
2244 | ||
2245 | /* Finally, we have a user-defined label. */ | |
2246 | if (lookup_attribute ("cold", DECL_ATTRIBUTES (decl))) | |
2247 | predict_edge_def (e, PRED_COLD_LABEL, NOT_TAKEN); | |
2248 | else if (lookup_attribute ("hot", DECL_ATTRIBUTES (decl))) | |
2249 | predict_edge_def (e, PRED_HOT_LABEL, TAKEN); | |
2250 | } | |
2251 | } | |
2252 | ||
675d86b2 | 2253 | /* Predict early returns to be probable, as we've already taken |
2254 | care for error returns and other cases are often used for | |
2255 | fast paths through function. | |
2256 | ||
2257 | Since we've already removed the return statements, we are | |
2258 | looking for CFG like: | |
2259 | ||
2260 | if (conditional) | |
2261 | { | |
2262 | .. | |
2263 | goto return_block | |
2264 | } | |
2265 | some other blocks | |
2266 | return_block: | |
2267 | return_stmt. */ | |
2268 | if (e->dest != bb->next_bb | |
34154e27 | 2269 | && e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) |
675d86b2 | 2270 | && single_succ_p (e->dest) |
34154e27 | 2271 | && single_succ_edge (e->dest)->dest == EXIT_BLOCK_PTR_FOR_FN (cfun) |
675d86b2 | 2272 | && (last = last_stmt (e->dest)) != NULL |
2273 | && gimple_code (last) == GIMPLE_RETURN) | |
2274 | { | |
2275 | edge e1; | |
2276 | edge_iterator ei1; | |
2277 | ||
2278 | if (single_succ_p (bb)) | |
2279 | { | |
2280 | FOR_EACH_EDGE (e1, ei1, bb->preds) | |
2281 | if (!predicted_by_p (e1->src, PRED_NULL_RETURN) | |
2282 | && !predicted_by_p (e1->src, PRED_CONST_RETURN) | |
2283 | && !predicted_by_p (e1->src, PRED_NEGATIVE_RETURN)) | |
2284 | predict_edge_def (e1, PRED_TREE_EARLY_RETURN, NOT_TAKEN); | |
2285 | } | |
2286 | else | |
2287 | if (!predicted_by_p (e->src, PRED_NULL_RETURN) | |
2288 | && !predicted_by_p (e->src, PRED_CONST_RETURN) | |
2289 | && !predicted_by_p (e->src, PRED_NEGATIVE_RETURN)) | |
2290 | predict_edge_def (e, PRED_TREE_EARLY_RETURN, NOT_TAKEN); | |
2291 | } | |
2292 | ||
2293 | /* Look for block we are guarding (ie we dominate it, | |
2294 | but it doesn't postdominate us). */ | |
34154e27 | 2295 | if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) && e->dest != bb |
675d86b2 | 2296 | && dominated_by_p (CDI_DOMINATORS, e->dest, e->src) |
2297 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e->dest)) | |
2298 | { | |
2299 | gimple_stmt_iterator bi; | |
2300 | ||
2301 | /* The call heuristic claims that a guarded function call | |
2302 | is improbable. This is because such calls are often used | |
2303 | to signal exceptional situations such as printing error | |
2304 | messages. */ | |
2305 | for (bi = gsi_start_bb (e->dest); !gsi_end_p (bi); | |
2306 | gsi_next (&bi)) | |
2307 | { | |
42acab1c | 2308 | gimple *stmt = gsi_stmt (bi); |
675d86b2 | 2309 | if (is_gimple_call (stmt) |
2310 | /* Constant and pure calls are hardly used to signalize | |
2311 | something exceptional. */ | |
2312 | && gimple_has_side_effects (stmt)) | |
2313 | { | |
2314 | predict_edge_def (e, PRED_CALL, NOT_TAKEN); | |
2315 | break; | |
2316 | } | |
2317 | } | |
2318 | } | |
2319 | } | |
2320 | tree_predict_by_opcode (bb); | |
2321 | } | |
2322 | ||
2323 | /* Predict branch probabilities and estimate profile of the tree CFG. | |
2324 | This function can be called from the loop optimizers to recompute | |
2325 | the profile information. */ | |
2326 | ||
2327 | void | |
4ee9c684 | 2328 | tree_estimate_probability (void) |
2329 | { | |
2330 | basic_block bb; | |
4ee9c684 | 2331 | |
f816ec49 | 2332 | add_noreturn_fake_exit_edges (); |
4ee9c684 | 2333 | connect_infinite_loops_to_exit (); |
d8a0d6b8 | 2334 | /* We use loop_niter_by_eval, which requires that the loops have |
2335 | preheaders. */ | |
2336 | create_preheaders (CP_SIMPLE_PREHEADERS); | |
4ee9c684 | 2337 | calculate_dominance_info (CDI_POST_DOMINATORS); |
2338 | ||
06ecf488 | 2339 | bb_predictions = new hash_map<const_basic_block, edge_prediction *>; |
f816ec49 | 2340 | tree_bb_level_predictions (); |
d500fef3 | 2341 | record_loop_exits (); |
675d86b2 | 2342 | |
41f75a99 | 2343 | if (number_of_loops (cfun) > 1) |
7194de72 | 2344 | predict_loops (); |
4ee9c684 | 2345 | |
fc00614f | 2346 | FOR_EACH_BB_FN (bb, cfun) |
675d86b2 | 2347 | tree_estimate_probability_bb (bb); |
4ee9c684 | 2348 | |
fc00614f | 2349 | FOR_EACH_BB_FN (bb, cfun) |
3f5be5f4 | 2350 | combine_predictions_for_bb (bb); |
f81d9f78 | 2351 | |
382ecba7 | 2352 | if (flag_checking) |
2353 | bb_predictions->traverse<void *, assert_is_empty> (NULL); | |
2354 | ||
06ecf488 | 2355 | delete bb_predictions; |
b3723726 | 2356 | bb_predictions = NULL; |
2357 | ||
5327650f | 2358 | estimate_bb_frequencies (false); |
4ee9c684 | 2359 | free_dominance_info (CDI_POST_DOMINATORS); |
41d24834 | 2360 | remove_fake_exit_edges (); |
675d86b2 | 2361 | } |
89cfe6e5 | 2362 | \f |
f0b5f617 | 2363 | /* Predict edges to successors of CUR whose sources are not postdominated by |
d704ea82 | 2364 | BB by PRED and recurse to all postdominators. */ |
f816ec49 | 2365 | |
2366 | static void | |
d704ea82 | 2367 | predict_paths_for_bb (basic_block cur, basic_block bb, |
2368 | enum br_predictor pred, | |
d3443011 | 2369 | enum prediction taken, |
2370 | bitmap visited) | |
f816ec49 | 2371 | { |
2372 | edge e; | |
cd665a06 | 2373 | edge_iterator ei; |
d704ea82 | 2374 | basic_block son; |
f816ec49 | 2375 | |
d704ea82 | 2376 | /* We are looking for all edges forming edge cut induced by |
2377 | set of all blocks postdominated by BB. */ | |
2378 | FOR_EACH_EDGE (e, ei, cur->preds) | |
2379 | if (e->src->index >= NUM_FIXED_BLOCKS | |
2380 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, bb)) | |
f816ec49 | 2381 | { |
f1d5a92b | 2382 | edge e2; |
2383 | edge_iterator ei2; | |
2384 | bool found = false; | |
2385 | ||
5707768a | 2386 | /* Ignore fake edges and eh, we predict them as not taken anyway. */ |
2387 | if (e->flags & (EDGE_EH | EDGE_FAKE)) | |
f1d5a92b | 2388 | continue; |
d704ea82 | 2389 | gcc_assert (bb == cur || dominated_by_p (CDI_POST_DOMINATORS, cur, bb)); |
f1d5a92b | 2390 | |
d3443011 | 2391 | /* See if there is an edge from e->src that is not abnormal |
f1d5a92b | 2392 | and does not lead to BB. */ |
2393 | FOR_EACH_EDGE (e2, ei2, e->src->succs) | |
2394 | if (e2 != e | |
5707768a | 2395 | && !(e2->flags & (EDGE_EH | EDGE_FAKE)) |
f1d5a92b | 2396 | && !dominated_by_p (CDI_POST_DOMINATORS, e2->dest, bb)) |
2397 | { | |
2398 | found = true; | |
2399 | break; | |
2400 | } | |
2401 | ||
2402 | /* If there is non-abnormal path leaving e->src, predict edge | |
2403 | using predictor. Otherwise we need to look for paths | |
d3443011 | 2404 | leading to e->src. |
2405 | ||
2406 | The second may lead to infinite loop in the case we are predicitng | |
2407 | regions that are only reachable by abnormal edges. We simply | |
2408 | prevent visiting given BB twice. */ | |
f1d5a92b | 2409 | if (found) |
2410 | predict_edge_def (e, pred, taken); | |
6e3803fb | 2411 | else if (bitmap_set_bit (visited, e->src->index)) |
d3443011 | 2412 | predict_paths_for_bb (e->src, e->src, pred, taken, visited); |
f816ec49 | 2413 | } |
d704ea82 | 2414 | for (son = first_dom_son (CDI_POST_DOMINATORS, cur); |
2415 | son; | |
2416 | son = next_dom_son (CDI_POST_DOMINATORS, son)) | |
d3443011 | 2417 | predict_paths_for_bb (son, bb, pred, taken, visited); |
d704ea82 | 2418 | } |
f816ec49 | 2419 | |
d704ea82 | 2420 | /* Sets branch probabilities according to PREDiction and |
2421 | FLAGS. */ | |
f816ec49 | 2422 | |
d704ea82 | 2423 | static void |
2424 | predict_paths_leading_to (basic_block bb, enum br_predictor pred, | |
2425 | enum prediction taken) | |
2426 | { | |
d3443011 | 2427 | bitmap visited = BITMAP_ALLOC (NULL); |
2428 | predict_paths_for_bb (bb, bb, pred, taken, visited); | |
2429 | BITMAP_FREE (visited); | |
f816ec49 | 2430 | } |
5707768a | 2431 | |
2432 | /* Like predict_paths_leading_to but take edge instead of basic block. */ | |
2433 | ||
2434 | static void | |
2435 | predict_paths_leading_to_edge (edge e, enum br_predictor pred, | |
2436 | enum prediction taken) | |
2437 | { | |
2438 | bool has_nonloop_edge = false; | |
2439 | edge_iterator ei; | |
2440 | edge e2; | |
2441 | ||
2442 | basic_block bb = e->src; | |
2443 | FOR_EACH_EDGE (e2, ei, bb->succs) | |
2444 | if (e2->dest != e->src && e2->dest != e->dest | |
2445 | && !(e->flags & (EDGE_EH | EDGE_FAKE)) | |
2446 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e2->dest)) | |
2447 | { | |
2448 | has_nonloop_edge = true; | |
2449 | break; | |
2450 | } | |
2451 | if (!has_nonloop_edge) | |
d3443011 | 2452 | { |
2453 | bitmap visited = BITMAP_ALLOC (NULL); | |
2454 | predict_paths_for_bb (bb, bb, pred, taken, visited); | |
2455 | BITMAP_FREE (visited); | |
2456 | } | |
5707768a | 2457 | else |
2458 | predict_edge_def (e, pred, taken); | |
2459 | } | |
cd0fe062 | 2460 | \f |
e725f898 | 2461 | /* This is used to carry information about basic blocks. It is |
f81d9f78 | 2462 | attached to the AUX field of the standard CFG block. */ |
2463 | ||
9908fe4d | 2464 | struct block_info |
f81d9f78 | 2465 | { |
2466 | /* Estimated frequency of execution of basic_block. */ | |
e9d7220b | 2467 | sreal frequency; |
f81d9f78 | 2468 | |
2469 | /* To keep queue of basic blocks to process. */ | |
2470 | basic_block next; | |
2471 | ||
4a82352a | 2472 | /* Number of predecessors we need to visit first. */ |
4ad72a03 | 2473 | int npredecessors; |
9908fe4d | 2474 | }; |
f81d9f78 | 2475 | |
2476 | /* Similar information for edges. */ | |
9908fe4d | 2477 | struct edge_prob_info |
f81d9f78 | 2478 | { |
77aa6362 | 2479 | /* In case edge is a loopback edge, the probability edge will be reached |
f81d9f78 | 2480 | in case header is. Estimated number of iterations of the loop can be |
56ff4880 | 2481 | then computed as 1 / (1 - back_edge_prob). */ |
e9d7220b | 2482 | sreal back_edge_prob; |
77aa6362 | 2483 | /* True if the edge is a loopback edge in the natural loop. */ |
74cbb553 | 2484 | unsigned int back_edge:1; |
9908fe4d | 2485 | }; |
f81d9f78 | 2486 | |
9908fe4d | 2487 | #define BLOCK_INFO(B) ((block_info *) (B)->aux) |
886c1262 | 2488 | #undef EDGE_INFO |
9908fe4d | 2489 | #define EDGE_INFO(E) ((edge_prob_info *) (E)->aux) |
f81d9f78 | 2490 | |
2491 | /* Helper function for estimate_bb_frequencies. | |
88e6f696 | 2492 | Propagate the frequencies in blocks marked in |
2493 | TOVISIT, starting in HEAD. */ | |
e6751e9a | 2494 | |
f81d9f78 | 2495 | static void |
88e6f696 | 2496 | propagate_freq (basic_block head, bitmap tovisit) |
f81d9f78 | 2497 | { |
4c26117a | 2498 | basic_block bb; |
2499 | basic_block last; | |
9ea83aa5 | 2500 | unsigned i; |
f81d9f78 | 2501 | edge e; |
2502 | basic_block nextbb; | |
b1bb9b10 | 2503 | bitmap_iterator bi; |
312866af | 2504 | |
4a82352a | 2505 | /* For each basic block we need to visit count number of his predecessors |
312866af | 2506 | we need to visit first. */ |
b1bb9b10 | 2507 | EXECUTE_IF_SET_IN_BITMAP (tovisit, 0, i, bi) |
312866af | 2508 | { |
b1bb9b10 | 2509 | edge_iterator ei; |
2510 | int count = 0; | |
2511 | ||
f5a6b05f | 2512 | bb = BASIC_BLOCK_FOR_FN (cfun, i); |
e6751e9a | 2513 | |
b1bb9b10 | 2514 | FOR_EACH_EDGE (e, ei, bb->preds) |
2515 | { | |
2516 | bool visit = bitmap_bit_p (tovisit, e->src->index); | |
2517 | ||
2518 | if (visit && !(e->flags & EDGE_DFS_BACK)) | |
2519 | count++; | |
2520 | else if (visit && dump_file && !EDGE_INFO (e)->back_edge) | |
2521 | fprintf (dump_file, | |
2522 | "Irreducible region hit, ignoring edge to %i->%i\n", | |
2523 | e->src->index, bb->index); | |
312866af | 2524 | } |
9ea83aa5 | 2525 | BLOCK_INFO (bb)->npredecessors = count; |
555e8b05 | 2526 | /* When function never returns, we will never process exit block. */ |
34154e27 | 2527 | if (!count && bb == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
555e8b05 | 2528 | bb->count = bb->frequency = 0; |
312866af | 2529 | } |
f81d9f78 | 2530 | |
8201d1f6 | 2531 | BLOCK_INFO (head)->frequency = 1; |
4c26117a | 2532 | last = head; |
2533 | for (bb = head; bb; bb = nextbb) | |
f81d9f78 | 2534 | { |
cd665a06 | 2535 | edge_iterator ei; |
8201d1f6 | 2536 | sreal cyclic_probability = 0; |
2537 | sreal frequency = 0; | |
f81d9f78 | 2538 | |
2539 | nextbb = BLOCK_INFO (bb)->next; | |
2540 | BLOCK_INFO (bb)->next = NULL; | |
2541 | ||
2542 | /* Compute frequency of basic block. */ | |
2543 | if (bb != head) | |
2544 | { | |
382ecba7 | 2545 | if (flag_checking) |
2546 | FOR_EACH_EDGE (e, ei, bb->preds) | |
2547 | gcc_assert (!bitmap_bit_p (tovisit, e->src->index) | |
2548 | || (e->flags & EDGE_DFS_BACK)); | |
f81d9f78 | 2549 | |
cd665a06 | 2550 | FOR_EACH_EDGE (e, ei, bb->preds) |
f81d9f78 | 2551 | if (EDGE_INFO (e)->back_edge) |
56ff4880 | 2552 | { |
23a92fc7 | 2553 | cyclic_probability += EDGE_INFO (e)->back_edge_prob; |
56ff4880 | 2554 | } |
312866af | 2555 | else if (!(e->flags & EDGE_DFS_BACK)) |
56ff4880 | 2556 | { |
56ff4880 | 2557 | /* frequency += (e->probability |
2558 | * BLOCK_INFO (e->src)->frequency / | |
2559 | REG_BR_PROB_BASE); */ | |
2560 | ||
8201d1f6 | 2561 | sreal tmp = e->probability; |
23a92fc7 | 2562 | tmp *= BLOCK_INFO (e->src)->frequency; |
2563 | tmp *= real_inv_br_prob_base; | |
2564 | frequency += tmp; | |
56ff4880 | 2565 | } |
2566 | ||
8201d1f6 | 2567 | if (cyclic_probability == 0) |
e9d7220b | 2568 | { |
23a92fc7 | 2569 | BLOCK_INFO (bb)->frequency = frequency; |
e9d7220b | 2570 | } |
2e3c56e8 | 2571 | else |
2572 | { | |
23a92fc7 | 2573 | if (cyclic_probability > real_almost_one) |
2574 | cyclic_probability = real_almost_one; | |
f81d9f78 | 2575 | |
d598ad0d | 2576 | /* BLOCK_INFO (bb)->frequency = frequency |
e9d7220b | 2577 | / (1 - cyclic_probability) */ |
f81d9f78 | 2578 | |
8201d1f6 | 2579 | cyclic_probability = sreal (1) - cyclic_probability; |
23a92fc7 | 2580 | BLOCK_INFO (bb)->frequency = frequency / cyclic_probability; |
2e3c56e8 | 2581 | } |
f81d9f78 | 2582 | } |
2583 | ||
b1bb9b10 | 2584 | bitmap_clear_bit (tovisit, bb->index); |
f81d9f78 | 2585 | |
c6356c17 | 2586 | e = find_edge (bb, head); |
2587 | if (e) | |
2588 | { | |
c6356c17 | 2589 | /* EDGE_INFO (e)->back_edge_prob |
2590 | = ((e->probability * BLOCK_INFO (bb)->frequency) | |
2591 | / REG_BR_PROB_BASE); */ | |
48e1416a | 2592 | |
8201d1f6 | 2593 | sreal tmp = e->probability; |
23a92fc7 | 2594 | tmp *= BLOCK_INFO (bb)->frequency; |
2595 | EDGE_INFO (e)->back_edge_prob = tmp * real_inv_br_prob_base; | |
c6356c17 | 2596 | } |
f81d9f78 | 2597 | |
e725f898 | 2598 | /* Propagate to successor blocks. */ |
cd665a06 | 2599 | FOR_EACH_EDGE (e, ei, bb->succs) |
312866af | 2600 | if (!(e->flags & EDGE_DFS_BACK) |
4ad72a03 | 2601 | && BLOCK_INFO (e->dest)->npredecessors) |
f81d9f78 | 2602 | { |
4ad72a03 | 2603 | BLOCK_INFO (e->dest)->npredecessors--; |
2604 | if (!BLOCK_INFO (e->dest)->npredecessors) | |
312866af | 2605 | { |
2606 | if (!nextbb) | |
2607 | nextbb = e->dest; | |
2608 | else | |
2609 | BLOCK_INFO (last)->next = e->dest; | |
48e1416a | 2610 | |
312866af | 2611 | last = e->dest; |
2612 | } | |
cd665a06 | 2613 | } |
f81d9f78 | 2614 | } |
2615 | } | |
2616 | ||
5327650f | 2617 | /* Estimate frequencies in loops at same nest level. */ |
e6751e9a | 2618 | |
f81d9f78 | 2619 | static void |
88e6f696 | 2620 | estimate_loops_at_level (struct loop *first_loop) |
f81d9f78 | 2621 | { |
7fb12188 | 2622 | struct loop *loop; |
f81d9f78 | 2623 | |
2624 | for (loop = first_loop; loop; loop = loop->next) | |
2625 | { | |
f81d9f78 | 2626 | edge e; |
7fb12188 | 2627 | basic_block *bbs; |
862be747 | 2628 | unsigned i; |
88e6f696 | 2629 | bitmap tovisit = BITMAP_ALLOC (NULL); |
f81d9f78 | 2630 | |
88e6f696 | 2631 | estimate_loops_at_level (loop->inner); |
d598ad0d | 2632 | |
88e6f696 | 2633 | /* Find current loop back edge and mark it. */ |
2634 | e = loop_latch_edge (loop); | |
2635 | EDGE_INFO (e)->back_edge = 1; | |
7fb12188 | 2636 | |
2637 | bbs = get_loop_body (loop); | |
2638 | for (i = 0; i < loop->num_nodes; i++) | |
b1bb9b10 | 2639 | bitmap_set_bit (tovisit, bbs[i]->index); |
7fb12188 | 2640 | free (bbs); |
88e6f696 | 2641 | propagate_freq (loop->header, tovisit); |
2642 | BITMAP_FREE (tovisit); | |
f81d9f78 | 2643 | } |
2644 | } | |
2645 | ||
fa7637bd | 2646 | /* Propagates frequencies through structure of loops. */ |
88e6f696 | 2647 | |
2648 | static void | |
7194de72 | 2649 | estimate_loops (void) |
88e6f696 | 2650 | { |
2651 | bitmap tovisit = BITMAP_ALLOC (NULL); | |
2652 | basic_block bb; | |
2653 | ||
2654 | /* Start by estimating the frequencies in the loops. */ | |
41f75a99 | 2655 | if (number_of_loops (cfun) > 1) |
7194de72 | 2656 | estimate_loops_at_level (current_loops->tree_root->inner); |
88e6f696 | 2657 | |
2658 | /* Now propagate the frequencies through all the blocks. */ | |
ed7d889a | 2659 | FOR_ALL_BB_FN (bb, cfun) |
88e6f696 | 2660 | { |
2661 | bitmap_set_bit (tovisit, bb->index); | |
2662 | } | |
34154e27 | 2663 | propagate_freq (ENTRY_BLOCK_PTR_FOR_FN (cfun), tovisit); |
88e6f696 | 2664 | BITMAP_FREE (tovisit); |
2665 | } | |
2666 | ||
38a65d4e | 2667 | /* Drop the profile for NODE to guessed, and update its frequency based on |
901d3ddc | 2668 | whether it is expected to be hot given the CALL_COUNT. */ |
38a65d4e | 2669 | |
2670 | static void | |
901d3ddc | 2671 | drop_profile (struct cgraph_node *node, gcov_type call_count) |
38a65d4e | 2672 | { |
2673 | struct function *fn = DECL_STRUCT_FUNCTION (node->decl); | |
901d3ddc | 2674 | /* In the case where this was called by another function with a |
2675 | dropped profile, call_count will be 0. Since there are no | |
2676 | non-zero call counts to this function, we don't know for sure | |
2677 | whether it is hot, and therefore it will be marked normal below. */ | |
2678 | bool hot = maybe_hot_count_p (NULL, call_count); | |
38a65d4e | 2679 | |
2680 | if (dump_file) | |
2681 | fprintf (dump_file, | |
2682 | "Dropping 0 profile for %s/%i. %s based on calls.\n", | |
f1c8b4d7 | 2683 | node->name (), node->order, |
38a65d4e | 2684 | hot ? "Function is hot" : "Function is normal"); |
2685 | /* We only expect to miss profiles for functions that are reached | |
2686 | via non-zero call edges in cases where the function may have | |
2687 | been linked from another module or library (COMDATs and extern | |
901d3ddc | 2688 | templates). See the comments below for handle_missing_profiles. |
2689 | Also, only warn in cases where the missing counts exceed the | |
2690 | number of training runs. In certain cases with an execv followed | |
2691 | by a no-return call the profile for the no-return call is not | |
2692 | dumped and there can be a mismatch. */ | |
2693 | if (!DECL_COMDAT (node->decl) && !DECL_EXTERNAL (node->decl) | |
2694 | && call_count > profile_info->runs) | |
38a65d4e | 2695 | { |
2696 | if (flag_profile_correction) | |
2697 | { | |
2698 | if (dump_file) | |
2699 | fprintf (dump_file, | |
2700 | "Missing counts for called function %s/%i\n", | |
f1c8b4d7 | 2701 | node->name (), node->order); |
38a65d4e | 2702 | } |
2703 | else | |
901d3ddc | 2704 | warning (0, "Missing counts for called function %s/%i", |
f1c8b4d7 | 2705 | node->name (), node->order); |
38a65d4e | 2706 | } |
2707 | ||
3bedbae3 | 2708 | profile_status_for_fn (fn) |
38a65d4e | 2709 | = (flag_guess_branch_prob ? PROFILE_GUESSED : PROFILE_ABSENT); |
2710 | node->frequency | |
2711 | = hot ? NODE_FREQUENCY_HOT : NODE_FREQUENCY_NORMAL; | |
2712 | } | |
2713 | ||
2714 | /* In the case of COMDAT routines, multiple object files will contain the same | |
2715 | function and the linker will select one for the binary. In that case | |
2716 | all the other copies from the profile instrument binary will be missing | |
2717 | profile counts. Look for cases where this happened, due to non-zero | |
2718 | call counts going to 0-count functions, and drop the profile to guessed | |
2719 | so that we can use the estimated probabilities and avoid optimizing only | |
2720 | for size. | |
2721 | ||
2722 | The other case where the profile may be missing is when the routine | |
2723 | is not going to be emitted to the object file, e.g. for "extern template" | |
2724 | class methods. Those will be marked DECL_EXTERNAL. Emit a warning in | |
2725 | all other cases of non-zero calls to 0-count functions. */ | |
2726 | ||
2727 | void | |
2728 | handle_missing_profiles (void) | |
2729 | { | |
2730 | struct cgraph_node *node; | |
2731 | int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); | |
2732 | vec<struct cgraph_node *> worklist; | |
2733 | worklist.create (64); | |
2734 | ||
2735 | /* See if 0 count function has non-0 count callers. In this case we | |
2736 | lost some profile. Drop its function profile to PROFILE_GUESSED. */ | |
2737 | FOR_EACH_DEFINED_FUNCTION (node) | |
2738 | { | |
2739 | struct cgraph_edge *e; | |
2740 | gcov_type call_count = 0; | |
af48f0b1 | 2741 | gcov_type max_tp_first_run = 0; |
38a65d4e | 2742 | struct function *fn = DECL_STRUCT_FUNCTION (node->decl); |
2743 | ||
2744 | if (node->count) | |
2745 | continue; | |
2746 | for (e = node->callers; e; e = e->next_caller) | |
af48f0b1 | 2747 | { |
38a65d4e | 2748 | call_count += e->count; |
af48f0b1 | 2749 | |
2750 | if (e->caller->tp_first_run > max_tp_first_run) | |
2751 | max_tp_first_run = e->caller->tp_first_run; | |
2752 | } | |
2753 | ||
2754 | /* If time profile is missing, let assign the maximum that comes from | |
2755 | caller functions. */ | |
2756 | if (!node->tp_first_run && max_tp_first_run) | |
2757 | node->tp_first_run = max_tp_first_run + 1; | |
2758 | ||
38a65d4e | 2759 | if (call_count |
2760 | && fn && fn->cfg | |
2761 | && (call_count * unlikely_count_fraction >= profile_info->runs)) | |
2762 | { | |
901d3ddc | 2763 | drop_profile (node, call_count); |
38a65d4e | 2764 | worklist.safe_push (node); |
2765 | } | |
2766 | } | |
2767 | ||
2768 | /* Propagate the profile dropping to other 0-count COMDATs that are | |
2769 | potentially called by COMDATs we already dropped the profile on. */ | |
2770 | while (worklist.length () > 0) | |
2771 | { | |
2772 | struct cgraph_edge *e; | |
2773 | ||
2774 | node = worklist.pop (); | |
2775 | for (e = node->callees; e; e = e->next_caller) | |
2776 | { | |
2777 | struct cgraph_node *callee = e->callee; | |
2778 | struct function *fn = DECL_STRUCT_FUNCTION (callee->decl); | |
2779 | ||
2780 | if (callee->count > 0) | |
2781 | continue; | |
2782 | if (DECL_COMDAT (callee->decl) && fn && fn->cfg | |
3bedbae3 | 2783 | && profile_status_for_fn (fn) == PROFILE_READ) |
38a65d4e | 2784 | { |
901d3ddc | 2785 | drop_profile (node, 0); |
38a65d4e | 2786 | worklist.safe_push (callee); |
2787 | } | |
2788 | } | |
2789 | } | |
2790 | worklist.release (); | |
2791 | } | |
2792 | ||
3f18719c | 2793 | /* Convert counts measured by profile driven feedback to frequencies. |
2794 | Return nonzero iff there was any nonzero execution count. */ | |
e6751e9a | 2795 | |
ffedd254 | 2796 | int |
d598ad0d | 2797 | counts_to_freqs (void) |
f81d9f78 | 2798 | { |
3f18719c | 2799 | gcov_type count_max, true_count_max = 0; |
4c26117a | 2800 | basic_block bb; |
b3d6de89 | 2801 | |
38a65d4e | 2802 | /* Don't overwrite the estimated frequencies when the profile for |
2803 | the function is missing. We may drop this function PROFILE_GUESSED | |
2804 | later in drop_profile (). */ | |
94bed7c3 | 2805 | if (!flag_auto_profile && !ENTRY_BLOCK_PTR_FOR_FN (cfun)->count) |
38a65d4e | 2806 | return 0; |
2807 | ||
34154e27 | 2808 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
3f18719c | 2809 | true_count_max = MAX (bb->count, true_count_max); |
f81d9f78 | 2810 | |
3f18719c | 2811 | count_max = MAX (true_count_max, 1); |
34154e27 | 2812 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
4c26117a | 2813 | bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max; |
167b550b | 2814 | |
3f18719c | 2815 | return true_count_max; |
f81d9f78 | 2816 | } |
2817 | ||
e6751e9a | 2818 | /* Return true if function is likely to be expensive, so there is no point to |
2819 | optimize performance of prologue, epilogue or do inlining at the expense | |
41a6f238 | 2820 | of code size growth. THRESHOLD is the limit of number of instructions |
e6751e9a | 2821 | function can execute at average to be still considered not expensive. */ |
2822 | ||
f4c0c1a2 | 2823 | bool |
d598ad0d | 2824 | expensive_function_p (int threshold) |
f4c0c1a2 | 2825 | { |
2826 | unsigned int sum = 0; | |
4c26117a | 2827 | basic_block bb; |
27d0c333 | 2828 | unsigned int limit; |
f4c0c1a2 | 2829 | |
2830 | /* We can not compute accurately for large thresholds due to scaled | |
2831 | frequencies. */ | |
876760f6 | 2832 | gcc_assert (threshold <= BB_FREQ_MAX); |
f4c0c1a2 | 2833 | |
4a82352a | 2834 | /* Frequencies are out of range. This either means that function contains |
f4c0c1a2 | 2835 | internal loop executing more than BB_FREQ_MAX times or profile feedback |
2836 | is available and function has not been executed at all. */ | |
34154e27 | 2837 | if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency == 0) |
f4c0c1a2 | 2838 | return true; |
195731ad | 2839 | |
f4c0c1a2 | 2840 | /* Maximally BB_FREQ_MAX^2 so overflow won't happen. */ |
34154e27 | 2841 | limit = ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency * threshold; |
fc00614f | 2842 | FOR_EACH_BB_FN (bb, cfun) |
f4c0c1a2 | 2843 | { |
ee5f6585 | 2844 | rtx_insn *insn; |
f4c0c1a2 | 2845 | |
91f71fa3 | 2846 | FOR_BB_INSNS (bb, insn) |
e6751e9a | 2847 | if (active_insn_p (insn)) |
2848 | { | |
2849 | sum += bb->frequency; | |
2850 | if (sum > limit) | |
2851 | return true; | |
f4c0c1a2 | 2852 | } |
2853 | } | |
e6751e9a | 2854 | |
f4c0c1a2 | 2855 | return false; |
2856 | } | |
2857 | ||
5327650f | 2858 | /* Estimate and propagate basic block frequencies using the given branch |
2859 | probabilities. If FORCE is true, the frequencies are used to estimate | |
2860 | the counts even when there are already non-zero profile counts. */ | |
e6751e9a | 2861 | |
4ae20857 | 2862 | void |
5327650f | 2863 | estimate_bb_frequencies (bool force) |
f81d9f78 | 2864 | { |
4c26117a | 2865 | basic_block bb; |
e9d7220b | 2866 | sreal freq_max; |
56ff4880 | 2867 | |
f26d8580 | 2868 | if (force || profile_status_for_fn (cfun) != PROFILE_READ || !counts_to_freqs ()) |
429fa7fa | 2869 | { |
31e4010e | 2870 | static int real_values_initialized = 0; |
2871 | ||
2872 | if (!real_values_initialized) | |
2873 | { | |
fc22704f | 2874 | real_values_initialized = 1; |
8201d1f6 | 2875 | real_br_prob_base = REG_BR_PROB_BASE; |
2876 | real_bb_freq_max = BB_FREQ_MAX; | |
23a92fc7 | 2877 | real_one_half = sreal (1, -1); |
8201d1f6 | 2878 | real_inv_br_prob_base = sreal (1) / real_br_prob_base; |
2879 | real_almost_one = sreal (1) - real_inv_br_prob_base; | |
31e4010e | 2880 | } |
f81d9f78 | 2881 | |
429fa7fa | 2882 | mark_dfs_back_edges (); |
429fa7fa | 2883 | |
34154e27 | 2884 | single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))->probability = |
2885 | REG_BR_PROB_BASE; | |
429fa7fa | 2886 | |
2887 | /* Set up block info for each basic block. */ | |
9908fe4d | 2888 | alloc_aux_for_blocks (sizeof (block_info)); |
2889 | alloc_aux_for_edges (sizeof (edge_prob_info)); | |
34154e27 | 2890 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
f81d9f78 | 2891 | { |
f81d9f78 | 2892 | edge e; |
cd665a06 | 2893 | edge_iterator ei; |
429fa7fa | 2894 | |
cd665a06 | 2895 | FOR_EACH_EDGE (e, ei, bb->succs) |
f81d9f78 | 2896 | { |
8201d1f6 | 2897 | EDGE_INFO (e)->back_edge_prob = e->probability; |
23a92fc7 | 2898 | EDGE_INFO (e)->back_edge_prob *= real_inv_br_prob_base; |
f81d9f78 | 2899 | } |
f81d9f78 | 2900 | } |
e6751e9a | 2901 | |
5327650f | 2902 | /* First compute frequencies locally for each loop from innermost |
2903 | to outermost to examine frequencies for back edges. */ | |
7194de72 | 2904 | estimate_loops (); |
f81d9f78 | 2905 | |
8201d1f6 | 2906 | freq_max = 0; |
fc00614f | 2907 | FOR_EACH_BB_FN (bb, cfun) |
23a92fc7 | 2908 | if (freq_max < BLOCK_INFO (bb)->frequency) |
2909 | freq_max = BLOCK_INFO (bb)->frequency; | |
2e3c56e8 | 2910 | |
23a92fc7 | 2911 | freq_max = real_bb_freq_max / freq_max; |
34154e27 | 2912 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
56ff4880 | 2913 | { |
23a92fc7 | 2914 | sreal tmp = BLOCK_INFO (bb)->frequency * freq_max + real_one_half; |
2915 | bb->frequency = tmp.to_int (); | |
429fa7fa | 2916 | } |
e6751e9a | 2917 | |
429fa7fa | 2918 | free_aux_for_blocks (); |
2919 | free_aux_for_edges (); | |
2920 | } | |
2921 | compute_function_frequency (); | |
429fa7fa | 2922 | } |
f81d9f78 | 2923 | |
429fa7fa | 2924 | /* Decide whether function is hot, cold or unlikely executed. */ |
63aab97d | 2925 | void |
d598ad0d | 2926 | compute_function_frequency (void) |
429fa7fa | 2927 | { |
4c26117a | 2928 | basic_block bb; |
415d1b9a | 2929 | struct cgraph_node *node = cgraph_node::get (current_function_decl); |
e27f29dd | 2930 | |
0f9fb931 | 2931 | if (DECL_STATIC_CONSTRUCTOR (current_function_decl) |
2932 | || MAIN_NAME_P (DECL_NAME (current_function_decl))) | |
2933 | node->only_called_at_startup = true; | |
2934 | if (DECL_STATIC_DESTRUCTOR (current_function_decl)) | |
2935 | node->only_called_at_exit = true; | |
4c26117a | 2936 | |
f26d8580 | 2937 | if (profile_status_for_fn (cfun) != PROFILE_READ) |
5de92639 | 2938 | { |
125b6d78 | 2939 | int flags = flags_from_decl_or_type (current_function_decl); |
5de92639 | 2940 | if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl)) |
2941 | != NULL) | |
125b6d78 | 2942 | node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; |
5de92639 | 2943 | else if (lookup_attribute ("hot", DECL_ATTRIBUTES (current_function_decl)) |
2944 | != NULL) | |
125b6d78 | 2945 | node->frequency = NODE_FREQUENCY_HOT; |
2946 | else if (flags & ECF_NORETURN) | |
2947 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
2948 | else if (MAIN_NAME_P (DECL_NAME (current_function_decl))) | |
2949 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
2950 | else if (DECL_STATIC_CONSTRUCTOR (current_function_decl) | |
2951 | || DECL_STATIC_DESTRUCTOR (current_function_decl)) | |
2952 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
5de92639 | 2953 | return; |
2954 | } | |
e27f29dd | 2955 | |
2956 | /* Only first time try to drop function into unlikely executed. | |
2957 | After inlining the roundoff errors may confuse us. | |
2958 | Ipa-profile pass will drop functions only called from unlikely | |
2959 | functions to unlikely and that is most of what we care about. */ | |
2960 | if (!cfun->after_inlining) | |
2961 | node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; | |
fc00614f | 2962 | FOR_EACH_BB_FN (bb, cfun) |
f81d9f78 | 2963 | { |
8d672d12 | 2964 | if (maybe_hot_bb_p (cfun, bb)) |
429fa7fa | 2965 | { |
125b6d78 | 2966 | node->frequency = NODE_FREQUENCY_HOT; |
429fa7fa | 2967 | return; |
2968 | } | |
8d672d12 | 2969 | if (!probably_never_executed_bb_p (cfun, bb)) |
125b6d78 | 2970 | node->frequency = NODE_FREQUENCY_NORMAL; |
f81d9f78 | 2971 | } |
429fa7fa | 2972 | } |
f81d9f78 | 2973 | |
4a1849e3 | 2974 | /* Build PREDICT_EXPR. */ |
2975 | tree | |
2976 | build_predict_expr (enum br_predictor predictor, enum prediction taken) | |
2977 | { | |
08f62b1b | 2978 | tree t = build1 (PREDICT_EXPR, void_type_node, |
b3d480fb | 2979 | build_int_cst (integer_type_node, predictor)); |
b9c74b4d | 2980 | SET_PREDICT_EXPR_OUTCOME (t, taken); |
4a1849e3 | 2981 | return t; |
2982 | } | |
2983 | ||
2984 | const char * | |
2985 | predictor_name (enum br_predictor predictor) | |
2986 | { | |
2987 | return predictor_info[predictor].name; | |
2988 | } | |
2989 | ||
65b0537f | 2990 | /* Predict branch probabilities and estimate profile of the tree CFG. */ |
2991 | ||
cbe8bda8 | 2992 | namespace { |
2993 | ||
2994 | const pass_data pass_data_profile = | |
2995 | { | |
2996 | GIMPLE_PASS, /* type */ | |
2997 | "profile_estimate", /* name */ | |
2998 | OPTGROUP_NONE, /* optinfo_flags */ | |
cbe8bda8 | 2999 | TV_BRANCH_PROB, /* tv_id */ |
3000 | PROP_cfg, /* properties_required */ | |
3001 | 0, /* properties_provided */ | |
3002 | 0, /* properties_destroyed */ | |
3003 | 0, /* todo_flags_start */ | |
8b88439e | 3004 | 0, /* todo_flags_finish */ |
4ee9c684 | 3005 | }; |
1add270f | 3006 | |
cbe8bda8 | 3007 | class pass_profile : public gimple_opt_pass |
3008 | { | |
3009 | public: | |
9af5ce0c | 3010 | pass_profile (gcc::context *ctxt) |
3011 | : gimple_opt_pass (pass_data_profile, ctxt) | |
cbe8bda8 | 3012 | {} |
3013 | ||
3014 | /* opt_pass methods: */ | |
31315c24 | 3015 | virtual bool gate (function *) { return flag_guess_branch_prob; } |
65b0537f | 3016 | virtual unsigned int execute (function *); |
cbe8bda8 | 3017 | |
3018 | }; // class pass_profile | |
3019 | ||
65b0537f | 3020 | unsigned int |
3021 | pass_profile::execute (function *fun) | |
3022 | { | |
3023 | unsigned nb_loops; | |
3024 | ||
3a9f48e7 | 3025 | if (profile_status_for_fn (cfun) == PROFILE_GUESSED) |
3026 | return 0; | |
3027 | ||
65b0537f | 3028 | loop_optimizer_init (LOOPS_NORMAL); |
3029 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3030 | flow_loops_dump (dump_file, NULL, 0); | |
3031 | ||
3032 | mark_irreducible_loops (); | |
3033 | ||
3034 | nb_loops = number_of_loops (fun); | |
3035 | if (nb_loops > 1) | |
3036 | scev_initialize (); | |
3037 | ||
3038 | tree_estimate_probability (); | |
3039 | ||
3040 | if (nb_loops > 1) | |
3041 | scev_finalize (); | |
3042 | ||
3043 | loop_optimizer_finalize (); | |
3044 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3045 | gimple_dump_cfg (dump_file, dump_flags); | |
3046 | if (profile_status_for_fn (fun) == PROFILE_ABSENT) | |
3047 | profile_status_for_fn (fun) = PROFILE_GUESSED; | |
3048 | return 0; | |
3049 | } | |
3050 | ||
cbe8bda8 | 3051 | } // anon namespace |
3052 | ||
3053 | gimple_opt_pass * | |
3054 | make_pass_profile (gcc::context *ctxt) | |
3055 | { | |
3056 | return new pass_profile (ctxt); | |
3057 | } | |
3058 | ||
3059 | namespace { | |
3060 | ||
3061 | const pass_data pass_data_strip_predict_hints = | |
3062 | { | |
3063 | GIMPLE_PASS, /* type */ | |
3064 | "*strip_predict_hints", /* name */ | |
3065 | OPTGROUP_NONE, /* optinfo_flags */ | |
cbe8bda8 | 3066 | TV_BRANCH_PROB, /* tv_id */ |
3067 | PROP_cfg, /* properties_required */ | |
3068 | 0, /* properties_provided */ | |
3069 | 0, /* properties_destroyed */ | |
3070 | 0, /* todo_flags_start */ | |
8b88439e | 3071 | 0, /* todo_flags_finish */ |
1add270f | 3072 | }; |
555e8b05 | 3073 | |
cbe8bda8 | 3074 | class pass_strip_predict_hints : public gimple_opt_pass |
3075 | { | |
3076 | public: | |
9af5ce0c | 3077 | pass_strip_predict_hints (gcc::context *ctxt) |
3078 | : gimple_opt_pass (pass_data_strip_predict_hints, ctxt) | |
cbe8bda8 | 3079 | {} |
3080 | ||
3081 | /* opt_pass methods: */ | |
ae84f584 | 3082 | opt_pass * clone () { return new pass_strip_predict_hints (m_ctxt); } |
65b0537f | 3083 | virtual unsigned int execute (function *); |
cbe8bda8 | 3084 | |
3085 | }; // class pass_strip_predict_hints | |
3086 | ||
65b0537f | 3087 | /* Get rid of all builtin_expect calls and GIMPLE_PREDICT statements |
3088 | we no longer need. */ | |
3089 | unsigned int | |
3090 | pass_strip_predict_hints::execute (function *fun) | |
3091 | { | |
3092 | basic_block bb; | |
42acab1c | 3093 | gimple *ass_stmt; |
65b0537f | 3094 | tree var; |
3095 | ||
3096 | FOR_EACH_BB_FN (bb, fun) | |
3097 | { | |
3098 | gimple_stmt_iterator bi; | |
3099 | for (bi = gsi_start_bb (bb); !gsi_end_p (bi);) | |
3100 | { | |
42acab1c | 3101 | gimple *stmt = gsi_stmt (bi); |
65b0537f | 3102 | |
3103 | if (gimple_code (stmt) == GIMPLE_PREDICT) | |
3104 | { | |
3105 | gsi_remove (&bi, true); | |
3106 | continue; | |
3107 | } | |
3108 | else if (is_gimple_call (stmt)) | |
3109 | { | |
3110 | tree fndecl = gimple_call_fndecl (stmt); | |
3111 | ||
3112 | if ((fndecl | |
3113 | && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL | |
3114 | && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT | |
3115 | && gimple_call_num_args (stmt) == 2) | |
3116 | || (gimple_call_internal_p (stmt) | |
3117 | && gimple_call_internal_fn (stmt) == IFN_BUILTIN_EXPECT)) | |
3118 | { | |
3119 | var = gimple_call_lhs (stmt); | |
3120 | if (var) | |
3121 | { | |
3122 | ass_stmt | |
3123 | = gimple_build_assign (var, gimple_call_arg (stmt, 0)); | |
3124 | gsi_replace (&bi, ass_stmt, true); | |
3125 | } | |
3126 | else | |
3127 | { | |
3128 | gsi_remove (&bi, true); | |
3129 | continue; | |
3130 | } | |
3131 | } | |
3132 | } | |
3133 | gsi_next (&bi); | |
3134 | } | |
3135 | } | |
3136 | return 0; | |
3137 | } | |
3138 | ||
cbe8bda8 | 3139 | } // anon namespace |
3140 | ||
3141 | gimple_opt_pass * | |
3142 | make_pass_strip_predict_hints (gcc::context *ctxt) | |
3143 | { | |
3144 | return new pass_strip_predict_hints (ctxt); | |
3145 | } | |
3146 | ||
555e8b05 | 3147 | /* Rebuild function frequencies. Passes are in general expected to |
3148 | maintain profile by hand, however in some cases this is not possible: | |
3149 | for example when inlining several functions with loops freuqencies might run | |
3150 | out of scale and thus needs to be recomputed. */ | |
3151 | ||
3152 | void | |
3153 | rebuild_frequencies (void) | |
3154 | { | |
4b366dd3 | 3155 | timevar_push (TV_REBUILD_FREQUENCIES); |
5327650f | 3156 | |
3157 | /* When the max bb count in the function is small, there is a higher | |
3158 | chance that there were truncation errors in the integer scaling | |
3159 | of counts by inlining and other optimizations. This could lead | |
3160 | to incorrect classification of code as being cold when it isn't. | |
3161 | In that case, force the estimation of bb counts/frequencies from the | |
3162 | branch probabilities, rather than computing frequencies from counts, | |
3163 | which may also lead to frequencies incorrectly reduced to 0. There | |
3164 | is less precision in the probabilities, so we only do this for small | |
3165 | max counts. */ | |
3166 | gcov_type count_max = 0; | |
3167 | basic_block bb; | |
34154e27 | 3168 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
5327650f | 3169 | count_max = MAX (bb->count, count_max); |
3170 | ||
f26d8580 | 3171 | if (profile_status_for_fn (cfun) == PROFILE_GUESSED |
94bed7c3 | 3172 | || (!flag_auto_profile && profile_status_for_fn (cfun) == PROFILE_READ |
3173 | && count_max < REG_BR_PROB_BASE/10)) | |
555e8b05 | 3174 | { |
3175 | loop_optimizer_init (0); | |
3176 | add_noreturn_fake_exit_edges (); | |
3177 | mark_irreducible_loops (); | |
3178 | connect_infinite_loops_to_exit (); | |
5327650f | 3179 | estimate_bb_frequencies (true); |
555e8b05 | 3180 | remove_fake_exit_edges (); |
3181 | loop_optimizer_finalize (); | |
3182 | } | |
f26d8580 | 3183 | else if (profile_status_for_fn (cfun) == PROFILE_READ) |
555e8b05 | 3184 | counts_to_freqs (); |
3185 | else | |
3186 | gcc_unreachable (); | |
4b366dd3 | 3187 | timevar_pop (TV_REBUILD_FREQUENCIES); |
555e8b05 | 3188 | } |