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f1ebdfc5 | 1 | /* Branch prediction routines for the GNU compiler. |
5624e564 | 2 | Copyright (C) 2000-2015 Free Software Foundation, Inc. |
f1ebdfc5 | 3 | |
bfdade77 | 4 | This file is part of GCC. |
f1ebdfc5 | 5 | |
bfdade77 RK |
6 | GCC is free software; you can redistribute it and/or modify it under |
7 | the terms of the GNU General Public License as published by the Free | |
9dcd6f09 | 8 | Software Foundation; either version 3, or (at your option) any later |
bfdade77 | 9 | version. |
f1ebdfc5 | 10 | |
bfdade77 RK |
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. | |
f1ebdfc5 | 15 | |
bfdade77 | 16 | You should have received a copy of the GNU General Public License |
9dcd6f09 NC |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
f1ebdfc5 JE |
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" | |
3ef42a0c | 27 | Calder, Grunwald, Lindsay, Martin, Mozer, and Zorn; PLDI '95. */ |
f1ebdfc5 JE |
28 | |
29 | ||
30 | #include "config.h" | |
31 | #include "system.h" | |
4977bab6 ZW |
32 | #include "coretypes.h" |
33 | #include "tm.h" | |
40e23961 MC |
34 | #include "hash-set.h" |
35 | #include "machmode.h" | |
36 | #include "vec.h" | |
37 | #include "double-int.h" | |
38 | #include "input.h" | |
39 | #include "alias.h" | |
40 | #include "symtab.h" | |
41 | #include "wide-int.h" | |
42 | #include "inchash.h" | |
f1ebdfc5 | 43 | #include "tree.h" |
40e23961 | 44 | #include "fold-const.h" |
d8a2d370 | 45 | #include "calls.h" |
f1ebdfc5 JE |
46 | #include "rtl.h" |
47 | #include "tm_p.h" | |
efc9bd41 | 48 | #include "hard-reg-set.h" |
60393bbc | 49 | #include "predict.h" |
f1ebdfc5 | 50 | #include "function.h" |
60393bbc AM |
51 | #include "dominance.h" |
52 | #include "cfg.h" | |
53 | #include "cfganal.h" | |
54 | #include "basic-block.h" | |
55 | #include "insn-config.h" | |
56 | #include "regs.h" | |
57 | #include "flags.h" | |
59f2e9d8 | 58 | #include "profile.h" |
f1ebdfc5 | 59 | #include "except.h" |
718f9c0f | 60 | #include "diagnostic-core.h" |
f1ebdfc5 | 61 | #include "recog.h" |
36566b39 PK |
62 | #include "hashtab.h" |
63 | #include "statistics.h" | |
64 | #include "real.h" | |
65 | #include "fixed-value.h" | |
66 | #include "expmed.h" | |
67 | #include "dojump.h" | |
68 | #include "explow.h" | |
69 | #include "emit-rtl.h" | |
70 | #include "varasm.h" | |
71 | #include "stmt.h" | |
f1ebdfc5 | 72 | #include "expr.h" |
d79f9ec9 | 73 | #include "coverage.h" |
ac5e69da | 74 | #include "sreal.h" |
194734e9 JH |
75 | #include "params.h" |
76 | #include "target.h" | |
3d436d2a | 77 | #include "cfgloop.h" |
b787e7a2 | 78 | #include "hash-map.h" |
2fb9a547 AM |
79 | #include "tree-ssa-alias.h" |
80 | #include "internal-fn.h" | |
81 | #include "gimple-expr.h" | |
82 | #include "is-a.h" | |
442b4905 | 83 | #include "gimple.h" |
5be5c238 | 84 | #include "gimple-iterator.h" |
442b4905 | 85 | #include "gimple-ssa.h" |
c582198b AM |
86 | #include "plugin-api.h" |
87 | #include "ipa-ref.h" | |
442b4905 AM |
88 | #include "cgraph.h" |
89 | #include "tree-cfg.h" | |
90 | #include "tree-phinodes.h" | |
91 | #include "ssa-iterators.h" | |
e28030cf | 92 | #include "tree-ssa-loop-niter.h" |
442b4905 | 93 | #include "tree-ssa-loop.h" |
6de9cd9a | 94 | #include "tree-pass.h" |
b6acab32 | 95 | #include "tree-scalar-evolution.h" |
8aa18a7d | 96 | |
fbe3b30b SB |
97 | /* real constants: 0, 1, 1-1/REG_BR_PROB_BASE, REG_BR_PROB_BASE, |
98 | 1/REG_BR_PROB_BASE, 0.5, BB_FREQ_MAX. */ | |
fd27ffab | 99 | static sreal real_almost_one, real_br_prob_base, |
ac5e69da | 100 | real_inv_br_prob_base, real_one_half, real_bb_freq_max; |
f1ebdfc5 | 101 | |
9f215bf5 | 102 | static void combine_predictions_for_insn (rtx_insn *, basic_block); |
6de9cd9a | 103 | static void dump_prediction (FILE *, enum br_predictor, int, basic_block, int); |
3e4b9ad0 | 104 | static void predict_paths_leading_to (basic_block, enum br_predictor, enum prediction); |
5210bbc5 | 105 | static void predict_paths_leading_to_edge (edge, enum br_predictor, enum prediction); |
9f215bf5 | 106 | static bool can_predict_insn_p (const rtx_insn *); |
ee92cb46 | 107 | |
4db384c9 JH |
108 | /* Information we hold about each branch predictor. |
109 | Filled using information from predict.def. */ | |
bfdade77 | 110 | |
4db384c9 | 111 | struct predictor_info |
ee92cb46 | 112 | { |
8b60264b KG |
113 | const char *const name; /* Name used in the debugging dumps. */ |
114 | const int hitrate; /* Expected hitrate used by | |
115 | predict_insn_def call. */ | |
116 | const int flags; | |
4db384c9 | 117 | }; |
ee92cb46 | 118 | |
134d3a2e JH |
119 | /* Use given predictor without Dempster-Shaffer theory if it matches |
120 | using first_match heuristics. */ | |
121 | #define PRED_FLAG_FIRST_MATCH 1 | |
122 | ||
123 | /* Recompute hitrate in percent to our representation. */ | |
124 | ||
bfdade77 | 125 | #define HITRATE(VAL) ((int) ((VAL) * REG_BR_PROB_BASE + 50) / 100) |
134d3a2e JH |
126 | |
127 | #define DEF_PREDICTOR(ENUM, NAME, HITRATE, FLAGS) {NAME, HITRATE, FLAGS}, | |
bfdade77 | 128 | static const struct predictor_info predictor_info[]= { |
4db384c9 JH |
129 | #include "predict.def" |
130 | ||
dc297297 | 131 | /* Upper bound on predictors. */ |
134d3a2e | 132 | {NULL, 0, 0} |
4db384c9 JH |
133 | }; |
134 | #undef DEF_PREDICTOR | |
194734e9 | 135 | |
3250d724 | 136 | /* Return TRUE if frequency FREQ is considered to be hot. */ |
fb2fed03 JH |
137 | |
138 | static inline bool | |
2eb712b4 | 139 | maybe_hot_frequency_p (struct function *fun, int freq) |
3250d724 | 140 | { |
d52f5295 | 141 | struct cgraph_node *node = cgraph_node::get (fun->decl); |
7525bb7d JH |
142 | if (!profile_info |
143 | || !opt_for_fn (fun->decl, flag_branch_probabilities)) | |
3250d724 | 144 | { |
5fefcf92 | 145 | if (node->frequency == NODE_FREQUENCY_UNLIKELY_EXECUTED) |
3250d724 | 146 | return false; |
5fefcf92 | 147 | if (node->frequency == NODE_FREQUENCY_HOT) |
3250d724 JH |
148 | return true; |
149 | } | |
ea19eb9f | 150 | if (profile_status_for_fn (fun) == PROFILE_ABSENT) |
c3702ff9 | 151 | return true; |
5fefcf92 | 152 | if (node->frequency == NODE_FREQUENCY_EXECUTED_ONCE |
fefa31b5 | 153 | && freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency * 2 / 3)) |
5fefcf92 | 154 | return false; |
39c1b6db MP |
155 | if (PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION) == 0) |
156 | return false; | |
fefa31b5 | 157 | if (freq < (ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency |
2eb712b4 | 158 | / PARAM_VALUE (HOT_BB_FREQUENCY_FRACTION))) |
3250d724 JH |
159 | return false; |
160 | return true; | |
161 | } | |
162 | ||
0208f7da JH |
163 | static gcov_type min_count = -1; |
164 | ||
165 | /* Determine the threshold for hot BB counts. */ | |
166 | ||
167 | gcov_type | |
168 | get_hot_bb_threshold () | |
169 | { | |
170 | gcov_working_set_t *ws; | |
171 | if (min_count == -1) | |
172 | { | |
173 | ws = find_working_set (PARAM_VALUE (HOT_BB_COUNT_WS_PERMILLE)); | |
174 | gcc_assert (ws); | |
175 | min_count = ws->min_counter; | |
176 | } | |
177 | return min_count; | |
178 | } | |
179 | ||
180 | /* Set the threshold for hot BB counts. */ | |
181 | ||
182 | void | |
183 | set_hot_bb_threshold (gcov_type min) | |
184 | { | |
185 | min_count = min; | |
186 | } | |
187 | ||
fb2fed03 JH |
188 | /* Return TRUE if frequency FREQ is considered to be hot. */ |
189 | ||
be3c16c4 | 190 | bool |
2eb712b4 | 191 | maybe_hot_count_p (struct function *fun, gcov_type count) |
fb2fed03 | 192 | { |
ea19eb9f | 193 | if (fun && profile_status_for_fn (fun) != PROFILE_READ) |
fb2fed03 JH |
194 | return true; |
195 | /* Code executed at most once is not hot. */ | |
196 | if (profile_info->runs >= count) | |
197 | return false; | |
0208f7da | 198 | return (count >= get_hot_bb_threshold ()); |
fb2fed03 JH |
199 | } |
200 | ||
194734e9 | 201 | /* Return true in case BB can be CPU intensive and should be optimized |
d55d8fc7 | 202 | for maximal performance. */ |
194734e9 JH |
203 | |
204 | bool | |
2eb712b4 | 205 | maybe_hot_bb_p (struct function *fun, const_basic_block bb) |
194734e9 | 206 | { |
2eb712b4 | 207 | gcc_checking_assert (fun); |
ea19eb9f | 208 | if (profile_status_for_fn (fun) == PROFILE_READ) |
2eb712b4 MJ |
209 | return maybe_hot_count_p (fun, bb->count); |
210 | return maybe_hot_frequency_p (fun, bb->frequency); | |
3250d724 JH |
211 | } |
212 | ||
213 | /* Return true in case BB can be CPU intensive and should be optimized | |
214 | for maximal performance. */ | |
215 | ||
216 | bool | |
217 | maybe_hot_edge_p (edge e) | |
218 | { | |
0a6a6ac9 | 219 | if (profile_status_for_fn (cfun) == PROFILE_READ) |
2eb712b4 MJ |
220 | return maybe_hot_count_p (cfun, e->count); |
221 | return maybe_hot_frequency_p (cfun, EDGE_FREQUENCY (e)); | |
194734e9 JH |
222 | } |
223 | ||
79221839 TJ |
224 | /* Return true if profile COUNT and FREQUENCY, or function FUN static |
225 | node frequency reflects never being executed. */ | |
226 | ||
227 | static bool | |
228 | probably_never_executed (struct function *fun, | |
229 | gcov_type count, int frequency) | |
194734e9 | 230 | { |
2eb712b4 | 231 | gcc_checking_assert (fun); |
7525bb7d | 232 | if (profile_status_for_fn (fun) == PROFILE_READ) |
61a74079 | 233 | { |
bfaa17c1 TJ |
234 | int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); |
235 | if (count * unlikely_count_fraction >= profile_info->runs) | |
61a74079 | 236 | return false; |
79221839 | 237 | if (!frequency) |
61a74079 | 238 | return true; |
7525bb7d | 239 | if (!ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency) |
61a74079 | 240 | return false; |
7525bb7d | 241 | if (ENTRY_BLOCK_PTR_FOR_FN (fun)->count) |
61a74079 | 242 | { |
bfaa17c1 TJ |
243 | gcov_type computed_count; |
244 | /* Check for possibility of overflow, in which case entry bb count | |
245 | is large enough to do the division first without losing much | |
246 | precision. */ | |
7525bb7d | 247 | if (ENTRY_BLOCK_PTR_FOR_FN (fun)->count < REG_BR_PROB_BASE * |
fefa31b5 | 248 | REG_BR_PROB_BASE) |
bfaa17c1 TJ |
249 | { |
250 | gcov_type scaled_count | |
7525bb7d | 251 | = frequency * ENTRY_BLOCK_PTR_FOR_FN (fun)->count * |
fefa31b5 DM |
252 | unlikely_count_fraction; |
253 | computed_count = RDIV (scaled_count, | |
7525bb7d | 254 | ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency); |
bfaa17c1 TJ |
255 | } |
256 | else | |
257 | { | |
7525bb7d JH |
258 | computed_count = RDIV (ENTRY_BLOCK_PTR_FOR_FN (fun)->count, |
259 | ENTRY_BLOCK_PTR_FOR_FN (fun)->frequency); | |
bfaa17c1 TJ |
260 | computed_count *= frequency * unlikely_count_fraction; |
261 | } | |
262 | if (computed_count >= profile_info->runs) | |
263 | return false; | |
61a74079 JH |
264 | } |
265 | return true; | |
266 | } | |
7525bb7d | 267 | if ((!profile_info || !(opt_for_fn (fun->decl, flag_branch_probabilities))) |
d52f5295 | 268 | && (cgraph_node::get (fun->decl)->frequency |
581985d7 | 269 | == NODE_FREQUENCY_UNLIKELY_EXECUTED)) |
52bf96d2 | 270 | return true; |
194734e9 JH |
271 | return false; |
272 | } | |
273 | ||
600b5b1d | 274 | |
79221839 TJ |
275 | /* Return true in case BB is probably never executed. */ |
276 | ||
277 | bool | |
278 | probably_never_executed_bb_p (struct function *fun, const_basic_block bb) | |
279 | { | |
280 | return probably_never_executed (fun, bb->count, bb->frequency); | |
281 | } | |
282 | ||
283 | ||
600b5b1d TJ |
284 | /* Return true in case edge E is probably never executed. */ |
285 | ||
286 | bool | |
287 | probably_never_executed_edge_p (struct function *fun, edge e) | |
288 | { | |
79221839 | 289 | return probably_never_executed (fun, e->count, EDGE_FREQUENCY (e)); |
600b5b1d TJ |
290 | } |
291 | ||
e6416b30 JH |
292 | /* Return true when current function should always be optimized for size. */ |
293 | ||
294 | bool | |
295 | optimize_function_for_size_p (struct function *fun) | |
296 | { | |
e6416b30 | 297 | if (!fun || !fun->decl) |
7525bb7d | 298 | return optimize_size; |
d52f5295 ML |
299 | cgraph_node *n = cgraph_node::get (fun->decl); |
300 | return n && n->optimize_for_size_p (); | |
e6416b30 JH |
301 | } |
302 | ||
3debdc1e JH |
303 | /* Return true when current function should always be optimized for speed. */ |
304 | ||
305 | bool | |
306 | optimize_function_for_speed_p (struct function *fun) | |
307 | { | |
308 | return !optimize_function_for_size_p (fun); | |
bf08ebeb JH |
309 | } |
310 | ||
311 | /* Return TRUE when BB should be optimized for size. */ | |
312 | ||
313 | bool | |
cc870036 | 314 | optimize_bb_for_size_p (const_basic_block bb) |
bf08ebeb | 315 | { |
fef5a0d9 RB |
316 | return (optimize_function_for_size_p (cfun) |
317 | || (bb && !maybe_hot_bb_p (cfun, bb))); | |
bf08ebeb JH |
318 | } |
319 | ||
320 | /* Return TRUE when BB should be optimized for speed. */ | |
321 | ||
322 | bool | |
cc870036 | 323 | optimize_bb_for_speed_p (const_basic_block bb) |
bf08ebeb JH |
324 | { |
325 | return !optimize_bb_for_size_p (bb); | |
326 | } | |
327 | ||
328 | /* Return TRUE when BB should be optimized for size. */ | |
329 | ||
330 | bool | |
331 | optimize_edge_for_size_p (edge e) | |
332 | { | |
3debdc1e | 333 | return optimize_function_for_size_p (cfun) || !maybe_hot_edge_p (e); |
bf08ebeb JH |
334 | } |
335 | ||
336 | /* Return TRUE when BB should be optimized for speed. */ | |
337 | ||
338 | bool | |
339 | optimize_edge_for_speed_p (edge e) | |
340 | { | |
341 | return !optimize_edge_for_size_p (e); | |
342 | } | |
343 | ||
344 | /* Return TRUE when BB should be optimized for size. */ | |
345 | ||
346 | bool | |
347 | optimize_insn_for_size_p (void) | |
348 | { | |
3debdc1e | 349 | return optimize_function_for_size_p (cfun) || !crtl->maybe_hot_insn_p; |
bf08ebeb JH |
350 | } |
351 | ||
352 | /* Return TRUE when BB should be optimized for speed. */ | |
353 | ||
354 | bool | |
355 | optimize_insn_for_speed_p (void) | |
356 | { | |
357 | return !optimize_insn_for_size_p (); | |
358 | } | |
359 | ||
cc870036 JH |
360 | /* Return TRUE when LOOP should be optimized for size. */ |
361 | ||
362 | bool | |
363 | optimize_loop_for_size_p (struct loop *loop) | |
364 | { | |
365 | return optimize_bb_for_size_p (loop->header); | |
366 | } | |
367 | ||
368 | /* Return TRUE when LOOP should be optimized for speed. */ | |
369 | ||
370 | bool | |
371 | optimize_loop_for_speed_p (struct loop *loop) | |
372 | { | |
373 | return optimize_bb_for_speed_p (loop->header); | |
374 | } | |
375 | ||
efd8f750 JH |
376 | /* Return TRUE when LOOP nest should be optimized for speed. */ |
377 | ||
378 | bool | |
379 | optimize_loop_nest_for_speed_p (struct loop *loop) | |
380 | { | |
381 | struct loop *l = loop; | |
382 | if (optimize_loop_for_speed_p (loop)) | |
383 | return true; | |
384 | l = loop->inner; | |
c16eb95f | 385 | while (l && l != loop) |
efd8f750 JH |
386 | { |
387 | if (optimize_loop_for_speed_p (l)) | |
388 | return true; | |
389 | if (l->inner) | |
390 | l = l->inner; | |
391 | else if (l->next) | |
392 | l = l->next; | |
393 | else | |
8bcf15f6 JH |
394 | { |
395 | while (l != loop && !l->next) | |
396 | l = loop_outer (l); | |
397 | if (l != loop) | |
398 | l = l->next; | |
399 | } | |
efd8f750 JH |
400 | } |
401 | return false; | |
402 | } | |
403 | ||
404 | /* Return TRUE when LOOP nest should be optimized for size. */ | |
405 | ||
406 | bool | |
407 | optimize_loop_nest_for_size_p (struct loop *loop) | |
408 | { | |
409 | return !optimize_loop_nest_for_speed_p (loop); | |
410 | } | |
411 | ||
3a4fd356 JH |
412 | /* Return true when edge E is likely to be well predictable by branch |
413 | predictor. */ | |
414 | ||
415 | bool | |
416 | predictable_edge_p (edge e) | |
417 | { | |
0a6a6ac9 | 418 | if (profile_status_for_fn (cfun) == PROFILE_ABSENT) |
3a4fd356 JH |
419 | return false; |
420 | if ((e->probability | |
421 | <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100) | |
422 | || (REG_BR_PROB_BASE - e->probability | |
423 | <= PARAM_VALUE (PARAM_PREDICTABLE_BRANCH_OUTCOME) * REG_BR_PROB_BASE / 100)) | |
424 | return true; | |
425 | return false; | |
426 | } | |
427 | ||
428 | ||
bf08ebeb JH |
429 | /* Set RTL expansion for BB profile. */ |
430 | ||
431 | void | |
432 | rtl_profile_for_bb (basic_block bb) | |
433 | { | |
2eb712b4 | 434 | crtl->maybe_hot_insn_p = maybe_hot_bb_p (cfun, bb); |
bf08ebeb JH |
435 | } |
436 | ||
437 | /* Set RTL expansion for edge profile. */ | |
438 | ||
439 | void | |
440 | rtl_profile_for_edge (edge e) | |
441 | { | |
442 | crtl->maybe_hot_insn_p = maybe_hot_edge_p (e); | |
443 | } | |
444 | ||
445 | /* Set RTL expansion to default mode (i.e. when profile info is not known). */ | |
446 | void | |
447 | default_rtl_profile (void) | |
448 | { | |
449 | crtl->maybe_hot_insn_p = true; | |
450 | } | |
451 | ||
969d70ca JH |
452 | /* Return true if the one of outgoing edges is already predicted by |
453 | PREDICTOR. */ | |
454 | ||
6de9cd9a | 455 | bool |
9678086d | 456 | rtl_predicted_by_p (const_basic_block bb, enum br_predictor predictor) |
969d70ca JH |
457 | { |
458 | rtx note; | |
a813c111 | 459 | if (!INSN_P (BB_END (bb))) |
969d70ca | 460 | return false; |
a813c111 | 461 | for (note = REG_NOTES (BB_END (bb)); note; note = XEXP (note, 1)) |
969d70ca JH |
462 | if (REG_NOTE_KIND (note) == REG_BR_PRED |
463 | && INTVAL (XEXP (XEXP (note, 0), 0)) == (int)predictor) | |
464 | return true; | |
465 | return false; | |
466 | } | |
ee92cb46 | 467 | |
fba4cb03 LB |
468 | /* Structure representing predictions in tree level. */ |
469 | ||
470 | struct edge_prediction { | |
471 | struct edge_prediction *ep_next; | |
472 | edge ep_edge; | |
473 | enum br_predictor ep_predictor; | |
474 | int ep_probability; | |
475 | }; | |
476 | ||
b787e7a2 TS |
477 | /* This map contains for a basic block the list of predictions for the |
478 | outgoing edges. */ | |
479 | ||
480 | static hash_map<const_basic_block, edge_prediction *> *bb_predictions; | |
481 | ||
6de9cd9a DN |
482 | /* Return true if the one of outgoing edges is already predicted by |
483 | PREDICTOR. */ | |
484 | ||
485 | bool | |
726a989a | 486 | gimple_predicted_by_p (const_basic_block bb, enum br_predictor predictor) |
6de9cd9a | 487 | { |
4aab792d | 488 | struct edge_prediction *i; |
b787e7a2 | 489 | edge_prediction **preds = bb_predictions->get (bb); |
f06b0a10 ZD |
490 | |
491 | if (!preds) | |
492 | return false; | |
b8698a0f | 493 | |
b787e7a2 | 494 | for (i = *preds; i; i = i->ep_next) |
59ced947 | 495 | if (i->ep_predictor == predictor) |
6de9cd9a DN |
496 | return true; |
497 | return false; | |
498 | } | |
499 | ||
2c9e13f3 | 500 | /* Return true when the probability of edge is reliable. |
b8698a0f | 501 | |
2c9e13f3 JH |
502 | The profile guessing code is good at predicting branch outcome (ie. |
503 | taken/not taken), that is predicted right slightly over 75% of time. | |
86c33cd0 | 504 | It is however notoriously poor on predicting the probability itself. |
2c9e13f3 JH |
505 | In general the profile appear a lot flatter (with probabilities closer |
506 | to 50%) than the reality so it is bad idea to use it to drive optimization | |
507 | such as those disabling dynamic branch prediction for well predictable | |
508 | branches. | |
509 | ||
510 | There are two exceptions - edges leading to noreturn edges and edges | |
511 | predicted by number of iterations heuristics are predicted well. This macro | |
512 | should be able to distinguish those, but at the moment it simply check for | |
513 | noreturn heuristic that is only one giving probability over 99% or bellow | |
86c33cd0 | 514 | 1%. In future we might want to propagate reliability information across the |
2c9e13f3 JH |
515 | CFG if we find this information useful on multiple places. */ |
516 | static bool | |
517 | probability_reliable_p (int prob) | |
518 | { | |
0a6a6ac9 DM |
519 | return (profile_status_for_fn (cfun) == PROFILE_READ |
520 | || (profile_status_for_fn (cfun) == PROFILE_GUESSED | |
2c9e13f3 JH |
521 | && (prob <= HITRATE (1) || prob >= HITRATE (99)))); |
522 | } | |
523 | ||
524 | /* Same predicate as above, working on edges. */ | |
525 | bool | |
ed7a4b4b | 526 | edge_probability_reliable_p (const_edge e) |
2c9e13f3 JH |
527 | { |
528 | return probability_reliable_p (e->probability); | |
529 | } | |
530 | ||
531 | /* Same predicate as edge_probability_reliable_p, working on notes. */ | |
532 | bool | |
ed7a4b4b | 533 | br_prob_note_reliable_p (const_rtx note) |
2c9e13f3 JH |
534 | { |
535 | gcc_assert (REG_NOTE_KIND (note) == REG_BR_PROB); | |
e5af9ddd | 536 | return probability_reliable_p (XINT (note, 0)); |
2c9e13f3 JH |
537 | } |
538 | ||
7d6d381a | 539 | static void |
9f215bf5 | 540 | predict_insn (rtx_insn *insn, enum br_predictor predictor, int probability) |
4db384c9 | 541 | { |
e16acfcd | 542 | gcc_assert (any_condjump_p (insn)); |
d50672ef JH |
543 | if (!flag_guess_branch_prob) |
544 | return; | |
bfdade77 | 545 | |
65c5f2a6 ILT |
546 | add_reg_note (insn, REG_BR_PRED, |
547 | gen_rtx_CONCAT (VOIDmode, | |
548 | GEN_INT ((int) predictor), | |
549 | GEN_INT ((int) probability))); | |
4db384c9 JH |
550 | } |
551 | ||
552 | /* Predict insn by given predictor. */ | |
bfdade77 | 553 | |
4db384c9 | 554 | void |
9f215bf5 | 555 | predict_insn_def (rtx_insn *insn, enum br_predictor predictor, |
79a490a9 | 556 | enum prediction taken) |
4db384c9 JH |
557 | { |
558 | int probability = predictor_info[(int) predictor].hitrate; | |
bfdade77 | 559 | |
4db384c9 JH |
560 | if (taken != TAKEN) |
561 | probability = REG_BR_PROB_BASE - probability; | |
bfdade77 | 562 | |
4db384c9 | 563 | predict_insn (insn, predictor, probability); |
ee92cb46 JH |
564 | } |
565 | ||
566 | /* Predict edge E with given probability if possible. */ | |
bfdade77 | 567 | |
4db384c9 | 568 | void |
6de9cd9a | 569 | rtl_predict_edge (edge e, enum br_predictor predictor, int probability) |
ee92cb46 | 570 | { |
9f215bf5 | 571 | rtx_insn *last_insn; |
a813c111 | 572 | last_insn = BB_END (e->src); |
ee92cb46 JH |
573 | |
574 | /* We can store the branch prediction information only about | |
575 | conditional jumps. */ | |
576 | if (!any_condjump_p (last_insn)) | |
577 | return; | |
578 | ||
579 | /* We always store probability of branching. */ | |
580 | if (e->flags & EDGE_FALLTHRU) | |
581 | probability = REG_BR_PROB_BASE - probability; | |
582 | ||
4db384c9 JH |
583 | predict_insn (last_insn, predictor, probability); |
584 | } | |
585 | ||
6de9cd9a DN |
586 | /* Predict edge E with the given PROBABILITY. */ |
587 | void | |
726a989a | 588 | gimple_predict_edge (edge e, enum br_predictor predictor, int probability) |
6de9cd9a | 589 | { |
0a6a6ac9 | 590 | gcc_assert (profile_status_for_fn (cfun) != PROFILE_GUESSED); |
fefa31b5 DM |
591 | if ((e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun) && EDGE_COUNT (e->src->succs) > |
592 | 1) | |
a00d11f0 | 593 | && flag_guess_branch_prob && optimize) |
e0342c26 | 594 | { |
f06b0a10 | 595 | struct edge_prediction *i = XNEW (struct edge_prediction); |
b787e7a2 | 596 | edge_prediction *&preds = bb_predictions->get_or_insert (e->src); |
6de9cd9a | 597 | |
b787e7a2 TS |
598 | i->ep_next = preds; |
599 | preds = i; | |
59ced947 RÁE |
600 | i->ep_probability = probability; |
601 | i->ep_predictor = predictor; | |
602 | i->ep_edge = e; | |
e0342c26 | 603 | } |
6de9cd9a DN |
604 | } |
605 | ||
3809e990 JH |
606 | /* Remove all predictions on given basic block that are attached |
607 | to edge E. */ | |
608 | void | |
609 | remove_predictions_associated_with_edge (edge e) | |
610 | { | |
f06b0a10 ZD |
611 | if (!bb_predictions) |
612 | return; | |
613 | ||
b787e7a2 | 614 | edge_prediction **preds = bb_predictions->get (e->src); |
f06b0a10 ZD |
615 | |
616 | if (preds) | |
3809e990 | 617 | { |
b787e7a2 | 618 | struct edge_prediction **prediction = preds; |
f06b0a10 ZD |
619 | struct edge_prediction *next; |
620 | ||
3809e990 JH |
621 | while (*prediction) |
622 | { | |
59ced947 | 623 | if ((*prediction)->ep_edge == e) |
f06b0a10 ZD |
624 | { |
625 | next = (*prediction)->ep_next; | |
626 | free (*prediction); | |
627 | *prediction = next; | |
628 | } | |
3809e990 | 629 | else |
59ced947 | 630 | prediction = &((*prediction)->ep_next); |
3809e990 JH |
631 | } |
632 | } | |
633 | } | |
634 | ||
f06b0a10 ZD |
635 | /* Clears the list of predictions stored for BB. */ |
636 | ||
637 | static void | |
638 | clear_bb_predictions (basic_block bb) | |
639 | { | |
b787e7a2 | 640 | edge_prediction **preds = bb_predictions->get (bb); |
f06b0a10 ZD |
641 | struct edge_prediction *pred, *next; |
642 | ||
643 | if (!preds) | |
644 | return; | |
645 | ||
b787e7a2 | 646 | for (pred = *preds; pred; pred = next) |
f06b0a10 ZD |
647 | { |
648 | next = pred->ep_next; | |
649 | free (pred); | |
650 | } | |
651 | *preds = NULL; | |
652 | } | |
653 | ||
2ffa9932 JH |
654 | /* Return true when we can store prediction on insn INSN. |
655 | At the moment we represent predictions only on conditional | |
656 | jumps, not at computed jump or other complicated cases. */ | |
657 | static bool | |
9f215bf5 | 658 | can_predict_insn_p (const rtx_insn *insn) |
2ffa9932 | 659 | { |
4b4bf941 | 660 | return (JUMP_P (insn) |
2ffa9932 | 661 | && any_condjump_p (insn) |
628f6a4e | 662 | && EDGE_COUNT (BLOCK_FOR_INSN (insn)->succs) >= 2); |
2ffa9932 JH |
663 | } |
664 | ||
4db384c9 | 665 | /* Predict edge E by given predictor if possible. */ |
bfdade77 | 666 | |
4db384c9 | 667 | void |
79a490a9 AJ |
668 | predict_edge_def (edge e, enum br_predictor predictor, |
669 | enum prediction taken) | |
4db384c9 JH |
670 | { |
671 | int probability = predictor_info[(int) predictor].hitrate; | |
672 | ||
673 | if (taken != TAKEN) | |
674 | probability = REG_BR_PROB_BASE - probability; | |
bfdade77 | 675 | |
4db384c9 JH |
676 | predict_edge (e, predictor, probability); |
677 | } | |
678 | ||
679 | /* Invert all branch predictions or probability notes in the INSN. This needs | |
680 | to be done each time we invert the condition used by the jump. */ | |
bfdade77 | 681 | |
4db384c9 | 682 | void |
79a490a9 | 683 | invert_br_probabilities (rtx insn) |
4db384c9 | 684 | { |
bfdade77 RK |
685 | rtx note; |
686 | ||
687 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) | |
688 | if (REG_NOTE_KIND (note) == REG_BR_PROB) | |
e5af9ddd | 689 | XINT (note, 0) = REG_BR_PROB_BASE - XINT (note, 0); |
bfdade77 RK |
690 | else if (REG_NOTE_KIND (note) == REG_BR_PRED) |
691 | XEXP (XEXP (note, 0), 1) | |
692 | = GEN_INT (REG_BR_PROB_BASE - INTVAL (XEXP (XEXP (note, 0), 1))); | |
4db384c9 JH |
693 | } |
694 | ||
695 | /* Dump information about the branch prediction to the output file. */ | |
bfdade77 | 696 | |
4db384c9 | 697 | static void |
6de9cd9a | 698 | dump_prediction (FILE *file, enum br_predictor predictor, int probability, |
79a490a9 | 699 | basic_block bb, int used) |
4db384c9 | 700 | { |
628f6a4e BE |
701 | edge e; |
702 | edge_iterator ei; | |
4db384c9 | 703 | |
6de9cd9a | 704 | if (!file) |
4db384c9 JH |
705 | return; |
706 | ||
628f6a4e BE |
707 | FOR_EACH_EDGE (e, ei, bb->succs) |
708 | if (! (e->flags & EDGE_FALLTHRU)) | |
709 | break; | |
4db384c9 | 710 | |
6de9cd9a | 711 | fprintf (file, " %s heuristics%s: %.1f%%", |
4db384c9 | 712 | predictor_info[predictor].name, |
bfdade77 | 713 | used ? "" : " (ignored)", probability * 100.0 / REG_BR_PROB_BASE); |
4db384c9 JH |
714 | |
715 | if (bb->count) | |
25c3a4ef | 716 | { |
16998094 | 717 | fprintf (file, " exec %" PRId64, bb->count); |
fbc2782e DD |
718 | if (e) |
719 | { | |
16998094 | 720 | fprintf (file, " hit %" PRId64, e->count); |
6de9cd9a | 721 | fprintf (file, " (%.1f%%)", e->count * 100.0 / bb->count); |
fbc2782e | 722 | } |
25c3a4ef | 723 | } |
bfdade77 | 724 | |
6de9cd9a | 725 | fprintf (file, "\n"); |
4db384c9 JH |
726 | } |
727 | ||
229031d0 | 728 | /* We can not predict the probabilities of outgoing edges of bb. Set them |
87022a6b JH |
729 | evenly and hope for the best. */ |
730 | static void | |
731 | set_even_probabilities (basic_block bb) | |
732 | { | |
733 | int nedges = 0; | |
734 | edge e; | |
628f6a4e | 735 | edge_iterator ei; |
87022a6b | 736 | |
628f6a4e | 737 | FOR_EACH_EDGE (e, ei, bb->succs) |
87022a6b JH |
738 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
739 | nedges ++; | |
628f6a4e | 740 | FOR_EACH_EDGE (e, ei, bb->succs) |
87022a6b JH |
741 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
742 | e->probability = (REG_BR_PROB_BASE + nedges / 2) / nedges; | |
743 | else | |
744 | e->probability = 0; | |
745 | } | |
746 | ||
4db384c9 JH |
747 | /* Combine all REG_BR_PRED notes into single probability and attach REG_BR_PROB |
748 | note if not already present. Remove now useless REG_BR_PRED notes. */ | |
bfdade77 | 749 | |
4db384c9 | 750 | static void |
9f215bf5 | 751 | combine_predictions_for_insn (rtx_insn *insn, basic_block bb) |
4db384c9 | 752 | { |
87022a6b JH |
753 | rtx prob_note; |
754 | rtx *pnote; | |
bfdade77 | 755 | rtx note; |
4db384c9 | 756 | int best_probability = PROB_EVEN; |
bbbbb16a | 757 | enum br_predictor best_predictor = END_PREDICTORS; |
134d3a2e JH |
758 | int combined_probability = REG_BR_PROB_BASE / 2; |
759 | int d; | |
d195b46f JH |
760 | bool first_match = false; |
761 | bool found = false; | |
4db384c9 | 762 | |
87022a6b JH |
763 | if (!can_predict_insn_p (insn)) |
764 | { | |
765 | set_even_probabilities (bb); | |
766 | return; | |
767 | } | |
768 | ||
769 | prob_note = find_reg_note (insn, REG_BR_PROB, 0); | |
770 | pnote = ®_NOTES (insn); | |
c263766c RH |
771 | if (dump_file) |
772 | fprintf (dump_file, "Predictions for insn %i bb %i\n", INSN_UID (insn), | |
0b17ab2f | 773 | bb->index); |
4db384c9 JH |
774 | |
775 | /* We implement "first match" heuristics and use probability guessed | |
6de9cd9a | 776 | by predictor with smallest index. */ |
bfdade77 RK |
777 | for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) |
778 | if (REG_NOTE_KIND (note) == REG_BR_PRED) | |
779 | { | |
81f40b79 ILT |
780 | enum br_predictor predictor = ((enum br_predictor) |
781 | INTVAL (XEXP (XEXP (note, 0), 0))); | |
bfdade77 RK |
782 | int probability = INTVAL (XEXP (XEXP (note, 0), 1)); |
783 | ||
784 | found = true; | |
785 | if (best_predictor > predictor) | |
786 | best_probability = probability, best_predictor = predictor; | |
787 | ||
788 | d = (combined_probability * probability | |
789 | + (REG_BR_PROB_BASE - combined_probability) | |
790 | * (REG_BR_PROB_BASE - probability)); | |
791 | ||
792 | /* Use FP math to avoid overflows of 32bit integers. */ | |
571a03b8 JJ |
793 | if (d == 0) |
794 | /* If one probability is 0% and one 100%, avoid division by zero. */ | |
795 | combined_probability = REG_BR_PROB_BASE / 2; | |
796 | else | |
797 | combined_probability = (((double) combined_probability) * probability | |
798 | * REG_BR_PROB_BASE / d + 0.5); | |
bfdade77 RK |
799 | } |
800 | ||
801 | /* Decide which heuristic to use. In case we didn't match anything, | |
802 | use no_prediction heuristic, in case we did match, use either | |
d195b46f JH |
803 | first match or Dempster-Shaffer theory depending on the flags. */ |
804 | ||
134d3a2e | 805 | if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH) |
d195b46f JH |
806 | first_match = true; |
807 | ||
808 | if (!found) | |
6de9cd9a DN |
809 | dump_prediction (dump_file, PRED_NO_PREDICTION, |
810 | combined_probability, bb, true); | |
d195b46f JH |
811 | else |
812 | { | |
6de9cd9a DN |
813 | dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, |
814 | bb, !first_match); | |
815 | dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, | |
816 | bb, first_match); | |
d195b46f JH |
817 | } |
818 | ||
819 | if (first_match) | |
134d3a2e | 820 | combined_probability = best_probability; |
6de9cd9a | 821 | dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); |
d195b46f JH |
822 | |
823 | while (*pnote) | |
824 | { | |
825 | if (REG_NOTE_KIND (*pnote) == REG_BR_PRED) | |
826 | { | |
81f40b79 ILT |
827 | enum br_predictor predictor = ((enum br_predictor) |
828 | INTVAL (XEXP (XEXP (*pnote, 0), 0))); | |
d195b46f JH |
829 | int probability = INTVAL (XEXP (XEXP (*pnote, 0), 1)); |
830 | ||
6de9cd9a | 831 | dump_prediction (dump_file, predictor, probability, bb, |
d195b46f | 832 | !first_match || best_predictor == predictor); |
6a4d6760 | 833 | *pnote = XEXP (*pnote, 1); |
d195b46f JH |
834 | } |
835 | else | |
6a4d6760 | 836 | pnote = &XEXP (*pnote, 1); |
d195b46f | 837 | } |
bfdade77 | 838 | |
4db384c9 JH |
839 | if (!prob_note) |
840 | { | |
e5af9ddd | 841 | add_int_reg_note (insn, REG_BR_PROB, combined_probability); |
bfdade77 | 842 | |
134d3a2e JH |
843 | /* Save the prediction into CFG in case we are seeing non-degenerated |
844 | conditional jump. */ | |
c5cbcccf | 845 | if (!single_succ_p (bb)) |
134d3a2e JH |
846 | { |
847 | BRANCH_EDGE (bb)->probability = combined_probability; | |
bfdade77 RK |
848 | FALLTHRU_EDGE (bb)->probability |
849 | = REG_BR_PROB_BASE - combined_probability; | |
134d3a2e | 850 | } |
4db384c9 | 851 | } |
c5cbcccf | 852 | else if (!single_succ_p (bb)) |
e53de54d | 853 | { |
e5af9ddd | 854 | int prob = XINT (prob_note, 0); |
e53de54d JH |
855 | |
856 | BRANCH_EDGE (bb)->probability = prob; | |
857 | FALLTHRU_EDGE (bb)->probability = REG_BR_PROB_BASE - prob; | |
858 | } | |
859 | else | |
c5cbcccf | 860 | single_succ_edge (bb)->probability = REG_BR_PROB_BASE; |
ee92cb46 JH |
861 | } |
862 | ||
6de9cd9a DN |
863 | /* Combine predictions into single probability and store them into CFG. |
864 | Remove now useless prediction entries. */ | |
f1ebdfc5 | 865 | |
6de9cd9a | 866 | static void |
10d22567 | 867 | combine_predictions_for_bb (basic_block bb) |
f1ebdfc5 | 868 | { |
6de9cd9a | 869 | int best_probability = PROB_EVEN; |
bbbbb16a | 870 | enum br_predictor best_predictor = END_PREDICTORS; |
6de9cd9a DN |
871 | int combined_probability = REG_BR_PROB_BASE / 2; |
872 | int d; | |
873 | bool first_match = false; | |
874 | bool found = false; | |
875 | struct edge_prediction *pred; | |
876 | int nedges = 0; | |
877 | edge e, first = NULL, second = NULL; | |
628f6a4e | 878 | edge_iterator ei; |
f1ebdfc5 | 879 | |
628f6a4e | 880 | FOR_EACH_EDGE (e, ei, bb->succs) |
6de9cd9a DN |
881 | if (!(e->flags & (EDGE_EH | EDGE_FAKE))) |
882 | { | |
628f6a4e | 883 | nedges ++; |
6de9cd9a DN |
884 | if (first && !second) |
885 | second = e; | |
886 | if (!first) | |
887 | first = e; | |
888 | } | |
889 | ||
b8698a0f | 890 | /* When there is no successor or only one choice, prediction is easy. |
6de9cd9a DN |
891 | |
892 | We are lazy for now and predict only basic blocks with two outgoing | |
893 | edges. It is possible to predict generic case too, but we have to | |
894 | ignore first match heuristics and do more involved combining. Implement | |
895 | this later. */ | |
896 | if (nedges != 2) | |
897 | { | |
87022a6b JH |
898 | if (!bb->count) |
899 | set_even_probabilities (bb); | |
f06b0a10 | 900 | clear_bb_predictions (bb); |
10d22567 ZD |
901 | if (dump_file) |
902 | fprintf (dump_file, "%i edges in bb %i predicted to even probabilities\n", | |
6de9cd9a DN |
903 | nedges, bb->index); |
904 | return; | |
905 | } | |
906 | ||
10d22567 ZD |
907 | if (dump_file) |
908 | fprintf (dump_file, "Predictions for bb %i\n", bb->index); | |
6de9cd9a | 909 | |
b787e7a2 | 910 | edge_prediction **preds = bb_predictions->get (bb); |
f06b0a10 | 911 | if (preds) |
6de9cd9a | 912 | { |
f06b0a10 ZD |
913 | /* We implement "first match" heuristics and use probability guessed |
914 | by predictor with smallest index. */ | |
b787e7a2 | 915 | for (pred = *preds; pred; pred = pred->ep_next) |
f06b0a10 | 916 | { |
bbbbb16a | 917 | enum br_predictor predictor = pred->ep_predictor; |
f06b0a10 | 918 | int probability = pred->ep_probability; |
6de9cd9a | 919 | |
f06b0a10 ZD |
920 | if (pred->ep_edge != first) |
921 | probability = REG_BR_PROB_BASE - probability; | |
6de9cd9a | 922 | |
f06b0a10 | 923 | found = true; |
c0ee0021 JH |
924 | /* First match heuristics would be widly confused if we predicted |
925 | both directions. */ | |
f06b0a10 | 926 | if (best_predictor > predictor) |
c0ee0021 JH |
927 | { |
928 | struct edge_prediction *pred2; | |
929 | int prob = probability; | |
930 | ||
ed9c79e1 JJ |
931 | for (pred2 = (struct edge_prediction *) *preds; |
932 | pred2; pred2 = pred2->ep_next) | |
c0ee0021 JH |
933 | if (pred2 != pred && pred2->ep_predictor == pred->ep_predictor) |
934 | { | |
935 | int probability2 = pred->ep_probability; | |
936 | ||
937 | if (pred2->ep_edge != first) | |
938 | probability2 = REG_BR_PROB_BASE - probability2; | |
939 | ||
b8698a0f | 940 | if ((probability < REG_BR_PROB_BASE / 2) != |
c0ee0021 JH |
941 | (probability2 < REG_BR_PROB_BASE / 2)) |
942 | break; | |
943 | ||
944 | /* If the same predictor later gave better result, go for it! */ | |
945 | if ((probability >= REG_BR_PROB_BASE / 2 && (probability2 > probability)) | |
946 | || (probability <= REG_BR_PROB_BASE / 2 && (probability2 < probability))) | |
947 | prob = probability2; | |
948 | } | |
949 | if (!pred2) | |
950 | best_probability = prob, best_predictor = predictor; | |
951 | } | |
6de9cd9a | 952 | |
f06b0a10 ZD |
953 | d = (combined_probability * probability |
954 | + (REG_BR_PROB_BASE - combined_probability) | |
955 | * (REG_BR_PROB_BASE - probability)); | |
6de9cd9a | 956 | |
f06b0a10 ZD |
957 | /* Use FP math to avoid overflows of 32bit integers. */ |
958 | if (d == 0) | |
959 | /* If one probability is 0% and one 100%, avoid division by zero. */ | |
960 | combined_probability = REG_BR_PROB_BASE / 2; | |
961 | else | |
962 | combined_probability = (((double) combined_probability) | |
963 | * probability | |
964 | * REG_BR_PROB_BASE / d + 0.5); | |
965 | } | |
6de9cd9a DN |
966 | } |
967 | ||
968 | /* Decide which heuristic to use. In case we didn't match anything, | |
969 | use no_prediction heuristic, in case we did match, use either | |
970 | first match or Dempster-Shaffer theory depending on the flags. */ | |
971 | ||
972 | if (predictor_info [best_predictor].flags & PRED_FLAG_FIRST_MATCH) | |
973 | first_match = true; | |
974 | ||
975 | if (!found) | |
10d22567 | 976 | dump_prediction (dump_file, PRED_NO_PREDICTION, combined_probability, bb, true); |
6de9cd9a DN |
977 | else |
978 | { | |
10d22567 | 979 | dump_prediction (dump_file, PRED_DS_THEORY, combined_probability, bb, |
6de9cd9a | 980 | !first_match); |
10d22567 | 981 | dump_prediction (dump_file, PRED_FIRST_MATCH, best_probability, bb, |
6de9cd9a DN |
982 | first_match); |
983 | } | |
984 | ||
985 | if (first_match) | |
986 | combined_probability = best_probability; | |
10d22567 | 987 | dump_prediction (dump_file, PRED_COMBINED, combined_probability, bb, true); |
6de9cd9a | 988 | |
f06b0a10 | 989 | if (preds) |
6de9cd9a | 990 | { |
d3bfe4de | 991 | for (pred = (struct edge_prediction *) *preds; pred; pred = pred->ep_next) |
f06b0a10 | 992 | { |
bbbbb16a | 993 | enum br_predictor predictor = pred->ep_predictor; |
f06b0a10 | 994 | int probability = pred->ep_probability; |
6de9cd9a | 995 | |
f06b0a10 ZD |
996 | if (pred->ep_edge != EDGE_SUCC (bb, 0)) |
997 | probability = REG_BR_PROB_BASE - probability; | |
998 | dump_prediction (dump_file, predictor, probability, bb, | |
999 | !first_match || best_predictor == predictor); | |
1000 | } | |
6de9cd9a | 1001 | } |
f06b0a10 | 1002 | clear_bb_predictions (bb); |
6de9cd9a | 1003 | |
87022a6b JH |
1004 | if (!bb->count) |
1005 | { | |
1006 | first->probability = combined_probability; | |
1007 | second->probability = REG_BR_PROB_BASE - combined_probability; | |
1008 | } | |
6de9cd9a DN |
1009 | } |
1010 | ||
9c04723a DC |
1011 | /* Check if T1 and T2 satisfy the IV_COMPARE condition. |
1012 | Return the SSA_NAME if the condition satisfies, NULL otherwise. | |
1013 | ||
1014 | T1 and T2 should be one of the following cases: | |
1015 | 1. T1 is SSA_NAME, T2 is NULL | |
1016 | 2. T1 is SSA_NAME, T2 is INTEGER_CST between [-4, 4] | |
1017 | 3. T2 is SSA_NAME, T1 is INTEGER_CST between [-4, 4] */ | |
1018 | ||
1019 | static tree | |
1020 | strips_small_constant (tree t1, tree t2) | |
1021 | { | |
1022 | tree ret = NULL; | |
1023 | int value = 0; | |
1024 | ||
1025 | if (!t1) | |
1026 | return NULL; | |
1027 | else if (TREE_CODE (t1) == SSA_NAME) | |
1028 | ret = t1; | |
9541ffee | 1029 | else if (tree_fits_shwi_p (t1)) |
9439e9a1 | 1030 | value = tree_to_shwi (t1); |
9c04723a DC |
1031 | else |
1032 | return NULL; | |
1033 | ||
1034 | if (!t2) | |
1035 | return ret; | |
9541ffee | 1036 | else if (tree_fits_shwi_p (t2)) |
9439e9a1 | 1037 | value = tree_to_shwi (t2); |
9c04723a DC |
1038 | else if (TREE_CODE (t2) == SSA_NAME) |
1039 | { | |
1040 | if (ret) | |
1041 | return NULL; | |
1042 | else | |
1043 | ret = t2; | |
1044 | } | |
1045 | ||
1046 | if (value <= 4 && value >= -4) | |
1047 | return ret; | |
1048 | else | |
1049 | return NULL; | |
1050 | } | |
1051 | ||
1052 | /* Return the SSA_NAME in T or T's operands. | |
1053 | Return NULL if SSA_NAME cannot be found. */ | |
1054 | ||
1055 | static tree | |
1056 | get_base_value (tree t) | |
1057 | { | |
1058 | if (TREE_CODE (t) == SSA_NAME) | |
1059 | return t; | |
1060 | ||
1061 | if (!BINARY_CLASS_P (t)) | |
1062 | return NULL; | |
1063 | ||
1064 | switch (TREE_OPERAND_LENGTH (t)) | |
1065 | { | |
1066 | case 1: | |
1067 | return strips_small_constant (TREE_OPERAND (t, 0), NULL); | |
1068 | case 2: | |
1069 | return strips_small_constant (TREE_OPERAND (t, 0), | |
1070 | TREE_OPERAND (t, 1)); | |
1071 | default: | |
1072 | return NULL; | |
1073 | } | |
1074 | } | |
1075 | ||
1076 | /* Check the compare STMT in LOOP. If it compares an induction | |
1077 | variable to a loop invariant, return true, and save | |
1078 | LOOP_INVARIANT, COMPARE_CODE and LOOP_STEP. | |
1079 | Otherwise return false and set LOOP_INVAIANT to NULL. */ | |
1080 | ||
1081 | static bool | |
538dd0b7 | 1082 | is_comparison_with_loop_invariant_p (gcond *stmt, struct loop *loop, |
9c04723a DC |
1083 | tree *loop_invariant, |
1084 | enum tree_code *compare_code, | |
ecd4f20a | 1085 | tree *loop_step, |
9c04723a DC |
1086 | tree *loop_iv_base) |
1087 | { | |
1088 | tree op0, op1, bound, base; | |
1089 | affine_iv iv0, iv1; | |
1090 | enum tree_code code; | |
ecd4f20a | 1091 | tree step; |
9c04723a DC |
1092 | |
1093 | code = gimple_cond_code (stmt); | |
1094 | *loop_invariant = NULL; | |
1095 | ||
1096 | switch (code) | |
1097 | { | |
1098 | case GT_EXPR: | |
1099 | case GE_EXPR: | |
1100 | case NE_EXPR: | |
1101 | case LT_EXPR: | |
1102 | case LE_EXPR: | |
1103 | case EQ_EXPR: | |
1104 | break; | |
1105 | ||
1106 | default: | |
1107 | return false; | |
1108 | } | |
1109 | ||
1110 | op0 = gimple_cond_lhs (stmt); | |
1111 | op1 = gimple_cond_rhs (stmt); | |
1112 | ||
1113 | if ((TREE_CODE (op0) != SSA_NAME && TREE_CODE (op0) != INTEGER_CST) | |
1114 | || (TREE_CODE (op1) != SSA_NAME && TREE_CODE (op1) != INTEGER_CST)) | |
1115 | return false; | |
1116 | if (!simple_iv (loop, loop_containing_stmt (stmt), op0, &iv0, true)) | |
1117 | return false; | |
1118 | if (!simple_iv (loop, loop_containing_stmt (stmt), op1, &iv1, true)) | |
1119 | return false; | |
1120 | if (TREE_CODE (iv0.step) != INTEGER_CST | |
1121 | || TREE_CODE (iv1.step) != INTEGER_CST) | |
1122 | return false; | |
1123 | if ((integer_zerop (iv0.step) && integer_zerop (iv1.step)) | |
1124 | || (!integer_zerop (iv0.step) && !integer_zerop (iv1.step))) | |
1125 | return false; | |
1126 | ||
1127 | if (integer_zerop (iv0.step)) | |
1128 | { | |
1129 | if (code != NE_EXPR && code != EQ_EXPR) | |
1130 | code = invert_tree_comparison (code, false); | |
1131 | bound = iv0.base; | |
1132 | base = iv1.base; | |
9541ffee | 1133 | if (tree_fits_shwi_p (iv1.step)) |
ecd4f20a | 1134 | step = iv1.step; |
9c04723a DC |
1135 | else |
1136 | return false; | |
1137 | } | |
1138 | else | |
1139 | { | |
1140 | bound = iv1.base; | |
1141 | base = iv0.base; | |
9541ffee | 1142 | if (tree_fits_shwi_p (iv0.step)) |
ecd4f20a | 1143 | step = iv0.step; |
9c04723a DC |
1144 | else |
1145 | return false; | |
1146 | } | |
1147 | ||
1148 | if (TREE_CODE (bound) != INTEGER_CST) | |
1149 | bound = get_base_value (bound); | |
1150 | if (!bound) | |
1151 | return false; | |
1152 | if (TREE_CODE (base) != INTEGER_CST) | |
1153 | base = get_base_value (base); | |
1154 | if (!base) | |
1155 | return false; | |
1156 | ||
1157 | *loop_invariant = bound; | |
1158 | *compare_code = code; | |
1159 | *loop_step = step; | |
1160 | *loop_iv_base = base; | |
1161 | return true; | |
1162 | } | |
1163 | ||
1164 | /* Compare two SSA_NAMEs: returns TRUE if T1 and T2 are value coherent. */ | |
1165 | ||
1166 | static bool | |
1167 | expr_coherent_p (tree t1, tree t2) | |
1168 | { | |
1169 | gimple stmt; | |
1170 | tree ssa_name_1 = NULL; | |
1171 | tree ssa_name_2 = NULL; | |
1172 | ||
1173 | gcc_assert (TREE_CODE (t1) == SSA_NAME || TREE_CODE (t1) == INTEGER_CST); | |
1174 | gcc_assert (TREE_CODE (t2) == SSA_NAME || TREE_CODE (t2) == INTEGER_CST); | |
1175 | ||
1176 | if (t1 == t2) | |
1177 | return true; | |
1178 | ||
1179 | if (TREE_CODE (t1) == INTEGER_CST && TREE_CODE (t2) == INTEGER_CST) | |
1180 | return true; | |
1181 | if (TREE_CODE (t1) == INTEGER_CST || TREE_CODE (t2) == INTEGER_CST) | |
1182 | return false; | |
1183 | ||
1184 | /* Check to see if t1 is expressed/defined with t2. */ | |
1185 | stmt = SSA_NAME_DEF_STMT (t1); | |
1186 | gcc_assert (stmt != NULL); | |
1187 | if (is_gimple_assign (stmt)) | |
1188 | { | |
1189 | ssa_name_1 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); | |
1190 | if (ssa_name_1 && ssa_name_1 == t2) | |
1191 | return true; | |
1192 | } | |
1193 | ||
1194 | /* Check to see if t2 is expressed/defined with t1. */ | |
1195 | stmt = SSA_NAME_DEF_STMT (t2); | |
1196 | gcc_assert (stmt != NULL); | |
1197 | if (is_gimple_assign (stmt)) | |
1198 | { | |
1199 | ssa_name_2 = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_USE); | |
1200 | if (ssa_name_2 && ssa_name_2 == t1) | |
1201 | return true; | |
1202 | } | |
1203 | ||
1204 | /* Compare if t1 and t2's def_stmts are identical. */ | |
1205 | if (ssa_name_2 != NULL && ssa_name_1 == ssa_name_2) | |
1206 | return true; | |
1207 | else | |
1208 | return false; | |
1209 | } | |
1210 | ||
1211 | /* Predict branch probability of BB when BB contains a branch that compares | |
1212 | an induction variable in LOOP with LOOP_IV_BASE_VAR to LOOP_BOUND_VAR. The | |
1213 | loop exit is compared using LOOP_BOUND_CODE, with step of LOOP_BOUND_STEP. | |
1214 | ||
1215 | E.g. | |
1216 | for (int i = 0; i < bound; i++) { | |
1217 | if (i < bound - 2) | |
1218 | computation_1(); | |
1219 | else | |
1220 | computation_2(); | |
1221 | } | |
1222 | ||
1223 | In this loop, we will predict the branch inside the loop to be taken. */ | |
1224 | ||
1225 | static void | |
1226 | predict_iv_comparison (struct loop *loop, basic_block bb, | |
1227 | tree loop_bound_var, | |
1228 | tree loop_iv_base_var, | |
1229 | enum tree_code loop_bound_code, | |
1230 | int loop_bound_step) | |
1231 | { | |
1232 | gimple stmt; | |
1233 | tree compare_var, compare_base; | |
1234 | enum tree_code compare_code; | |
ecd4f20a | 1235 | tree compare_step_var; |
9c04723a DC |
1236 | edge then_edge; |
1237 | edge_iterator ei; | |
1238 | ||
1239 | if (predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED) | |
1240 | || predicted_by_p (bb, PRED_LOOP_ITERATIONS) | |
1241 | || predicted_by_p (bb, PRED_LOOP_EXIT)) | |
1242 | return; | |
1243 | ||
1244 | stmt = last_stmt (bb); | |
1245 | if (!stmt || gimple_code (stmt) != GIMPLE_COND) | |
1246 | return; | |
538dd0b7 DM |
1247 | if (!is_comparison_with_loop_invariant_p (as_a <gcond *> (stmt), |
1248 | loop, &compare_var, | |
9c04723a | 1249 | &compare_code, |
ecd4f20a | 1250 | &compare_step_var, |
9c04723a DC |
1251 | &compare_base)) |
1252 | return; | |
1253 | ||
1254 | /* Find the taken edge. */ | |
1255 | FOR_EACH_EDGE (then_edge, ei, bb->succs) | |
1256 | if (then_edge->flags & EDGE_TRUE_VALUE) | |
1257 | break; | |
1258 | ||
1259 | /* When comparing an IV to a loop invariant, NE is more likely to be | |
1260 | taken while EQ is more likely to be not-taken. */ | |
1261 | if (compare_code == NE_EXPR) | |
1262 | { | |
1263 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1264 | return; | |
1265 | } | |
1266 | else if (compare_code == EQ_EXPR) | |
1267 | { | |
1268 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1269 | return; | |
1270 | } | |
1271 | ||
1272 | if (!expr_coherent_p (loop_iv_base_var, compare_base)) | |
1273 | return; | |
1274 | ||
1275 | /* If loop bound, base and compare bound are all constants, we can | |
1276 | calculate the probability directly. */ | |
9541ffee RS |
1277 | if (tree_fits_shwi_p (loop_bound_var) |
1278 | && tree_fits_shwi_p (compare_var) | |
1279 | && tree_fits_shwi_p (compare_base)) | |
9c04723a DC |
1280 | { |
1281 | int probability; | |
807e902e KZ |
1282 | bool overflow, overall_overflow = false; |
1283 | widest_int compare_count, tem; | |
ecd4f20a MP |
1284 | |
1285 | /* (loop_bound - base) / compare_step */ | |
807e902e KZ |
1286 | tem = wi::sub (wi::to_widest (loop_bound_var), |
1287 | wi::to_widest (compare_base), SIGNED, &overflow); | |
1288 | overall_overflow |= overflow; | |
1289 | widest_int loop_count = wi::div_trunc (tem, | |
1290 | wi::to_widest (compare_step_var), | |
1291 | SIGNED, &overflow); | |
1292 | overall_overflow |= overflow; | |
1293 | ||
1294 | if (!wi::neg_p (wi::to_widest (compare_step_var)) | |
9c04723a | 1295 | ^ (compare_code == LT_EXPR || compare_code == LE_EXPR)) |
ecd4f20a MP |
1296 | { |
1297 | /* (loop_bound - compare_bound) / compare_step */ | |
807e902e KZ |
1298 | tem = wi::sub (wi::to_widest (loop_bound_var), |
1299 | wi::to_widest (compare_var), SIGNED, &overflow); | |
1300 | overall_overflow |= overflow; | |
1301 | compare_count = wi::div_trunc (tem, wi::to_widest (compare_step_var), | |
1302 | SIGNED, &overflow); | |
1303 | overall_overflow |= overflow; | |
ecd4f20a | 1304 | } |
9c04723a | 1305 | else |
ecd4f20a MP |
1306 | { |
1307 | /* (compare_bound - base) / compare_step */ | |
807e902e KZ |
1308 | tem = wi::sub (wi::to_widest (compare_var), |
1309 | wi::to_widest (compare_base), SIGNED, &overflow); | |
1310 | overall_overflow |= overflow; | |
1311 | compare_count = wi::div_trunc (tem, wi::to_widest (compare_step_var), | |
1312 | SIGNED, &overflow); | |
1313 | overall_overflow |= overflow; | |
ecd4f20a | 1314 | } |
9c04723a | 1315 | if (compare_code == LE_EXPR || compare_code == GE_EXPR) |
ecd4f20a | 1316 | ++compare_count; |
9c04723a | 1317 | if (loop_bound_code == LE_EXPR || loop_bound_code == GE_EXPR) |
ecd4f20a | 1318 | ++loop_count; |
807e902e KZ |
1319 | if (wi::neg_p (compare_count)) |
1320 | compare_count = 0; | |
1321 | if (wi::neg_p (loop_count)) | |
1322 | loop_count = 0; | |
1323 | if (loop_count == 0) | |
9c04723a | 1324 | probability = 0; |
807e902e | 1325 | else if (wi::cmps (compare_count, loop_count) == 1) |
9c04723a DC |
1326 | probability = REG_BR_PROB_BASE; |
1327 | else | |
ecd4f20a | 1328 | { |
807e902e KZ |
1329 | tem = compare_count * REG_BR_PROB_BASE; |
1330 | tem = wi::udiv_trunc (tem, loop_count); | |
ecd4f20a MP |
1331 | probability = tem.to_uhwi (); |
1332 | } | |
1333 | ||
807e902e | 1334 | if (!overall_overflow) |
ecd4f20a MP |
1335 | predict_edge (then_edge, PRED_LOOP_IV_COMPARE, probability); |
1336 | ||
9c04723a DC |
1337 | return; |
1338 | } | |
1339 | ||
1340 | if (expr_coherent_p (loop_bound_var, compare_var)) | |
1341 | { | |
1342 | if ((loop_bound_code == LT_EXPR || loop_bound_code == LE_EXPR) | |
1343 | && (compare_code == LT_EXPR || compare_code == LE_EXPR)) | |
1344 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1345 | else if ((loop_bound_code == GT_EXPR || loop_bound_code == GE_EXPR) | |
1346 | && (compare_code == GT_EXPR || compare_code == GE_EXPR)) | |
1347 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1348 | else if (loop_bound_code == NE_EXPR) | |
1349 | { | |
1350 | /* If the loop backedge condition is "(i != bound)", we do | |
1351 | the comparison based on the step of IV: | |
1352 | * step < 0 : backedge condition is like (i > bound) | |
1353 | * step > 0 : backedge condition is like (i < bound) */ | |
1354 | gcc_assert (loop_bound_step != 0); | |
1355 | if (loop_bound_step > 0 | |
1356 | && (compare_code == LT_EXPR | |
1357 | || compare_code == LE_EXPR)) | |
1358 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1359 | else if (loop_bound_step < 0 | |
1360 | && (compare_code == GT_EXPR | |
1361 | || compare_code == GE_EXPR)) | |
1362 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1363 | else | |
1364 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1365 | } | |
1366 | else | |
1367 | /* The branch is predicted not-taken if loop_bound_code is | |
1368 | opposite with compare_code. */ | |
1369 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1370 | } | |
1371 | else if (expr_coherent_p (loop_iv_base_var, compare_var)) | |
1372 | { | |
1373 | /* For cases like: | |
1374 | for (i = s; i < h; i++) | |
1375 | if (i > s + 2) .... | |
1376 | The branch should be predicted taken. */ | |
1377 | if (loop_bound_step > 0 | |
1378 | && (compare_code == GT_EXPR || compare_code == GE_EXPR)) | |
1379 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1380 | else if (loop_bound_step < 0 | |
1381 | && (compare_code == LT_EXPR || compare_code == LE_EXPR)) | |
1382 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, TAKEN); | |
1383 | else | |
1384 | predict_edge_def (then_edge, PRED_LOOP_IV_COMPARE_GUESS, NOT_TAKEN); | |
1385 | } | |
1386 | } | |
16fdb75f DC |
1387 | |
1388 | /* Predict for extra loop exits that will lead to EXIT_EDGE. The extra loop | |
1389 | exits are resulted from short-circuit conditions that will generate an | |
1390 | if_tmp. E.g.: | |
1391 | ||
1392 | if (foo() || global > 10) | |
1393 | break; | |
1394 | ||
1395 | This will be translated into: | |
1396 | ||
1397 | BB3: | |
1398 | loop header... | |
1399 | BB4: | |
1400 | if foo() goto BB6 else goto BB5 | |
1401 | BB5: | |
1402 | if global > 10 goto BB6 else goto BB7 | |
1403 | BB6: | |
1404 | goto BB7 | |
1405 | BB7: | |
1406 | iftmp = (PHI 0(BB5), 1(BB6)) | |
1407 | if iftmp == 1 goto BB8 else goto BB3 | |
1408 | BB8: | |
1409 | outside of the loop... | |
1410 | ||
1411 | The edge BB7->BB8 is loop exit because BB8 is outside of the loop. | |
1412 | From the dataflow, we can infer that BB4->BB6 and BB5->BB6 are also loop | |
1413 | exits. This function takes BB7->BB8 as input, and finds out the extra loop | |
1414 | exits to predict them using PRED_LOOP_EXIT. */ | |
1415 | ||
1416 | static void | |
1417 | predict_extra_loop_exits (edge exit_edge) | |
1418 | { | |
1419 | unsigned i; | |
1420 | bool check_value_one; | |
538dd0b7 DM |
1421 | gimple lhs_def_stmt; |
1422 | gphi *phi_stmt; | |
16fdb75f | 1423 | tree cmp_rhs, cmp_lhs; |
538dd0b7 DM |
1424 | gimple last; |
1425 | gcond *cmp_stmt; | |
16fdb75f | 1426 | |
538dd0b7 DM |
1427 | last = last_stmt (exit_edge->src); |
1428 | if (!last) | |
1429 | return; | |
1430 | cmp_stmt = dyn_cast <gcond *> (last); | |
1431 | if (!cmp_stmt) | |
16fdb75f | 1432 | return; |
538dd0b7 | 1433 | |
16fdb75f DC |
1434 | cmp_rhs = gimple_cond_rhs (cmp_stmt); |
1435 | cmp_lhs = gimple_cond_lhs (cmp_stmt); | |
1436 | if (!TREE_CONSTANT (cmp_rhs) | |
1437 | || !(integer_zerop (cmp_rhs) || integer_onep (cmp_rhs))) | |
1438 | return; | |
1439 | if (TREE_CODE (cmp_lhs) != SSA_NAME) | |
1440 | return; | |
1441 | ||
1442 | /* If check_value_one is true, only the phi_args with value '1' will lead | |
1443 | to loop exit. Otherwise, only the phi_args with value '0' will lead to | |
1444 | loop exit. */ | |
1445 | check_value_one = (((integer_onep (cmp_rhs)) | |
1446 | ^ (gimple_cond_code (cmp_stmt) == EQ_EXPR)) | |
1447 | ^ ((exit_edge->flags & EDGE_TRUE_VALUE) != 0)); | |
1448 | ||
538dd0b7 DM |
1449 | lhs_def_stmt = SSA_NAME_DEF_STMT (cmp_lhs); |
1450 | if (!lhs_def_stmt) | |
1451 | return; | |
1452 | ||
1453 | phi_stmt = dyn_cast <gphi *> (lhs_def_stmt); | |
1454 | if (!phi_stmt) | |
16fdb75f DC |
1455 | return; |
1456 | ||
1457 | for (i = 0; i < gimple_phi_num_args (phi_stmt); i++) | |
1458 | { | |
1459 | edge e1; | |
1460 | edge_iterator ei; | |
1461 | tree val = gimple_phi_arg_def (phi_stmt, i); | |
1462 | edge e = gimple_phi_arg_edge (phi_stmt, i); | |
1463 | ||
1464 | if (!TREE_CONSTANT (val) || !(integer_zerop (val) || integer_onep (val))) | |
1465 | continue; | |
1466 | if ((check_value_one ^ integer_onep (val)) == 1) | |
1467 | continue; | |
1468 | if (EDGE_COUNT (e->src->succs) != 1) | |
1469 | { | |
1470 | predict_paths_leading_to_edge (e, PRED_LOOP_EXIT, NOT_TAKEN); | |
1471 | continue; | |
1472 | } | |
1473 | ||
1474 | FOR_EACH_EDGE (e1, ei, e->src->preds) | |
1475 | predict_paths_leading_to_edge (e1, PRED_LOOP_EXIT, NOT_TAKEN); | |
1476 | } | |
1477 | } | |
1478 | ||
d73be268 ZD |
1479 | /* Predict edge probabilities by exploiting loop structure. */ |
1480 | ||
6de9cd9a | 1481 | static void |
d73be268 | 1482 | predict_loops (void) |
6de9cd9a | 1483 | { |
42fd6772 | 1484 | struct loop *loop; |
0b92ff33 | 1485 | |
65169dcf JE |
1486 | /* Try to predict out blocks in a loop that are not part of a |
1487 | natural loop. */ | |
f0bd40b1 | 1488 | FOR_EACH_LOOP (loop, 0) |
f1ebdfc5 | 1489 | { |
2ecfd709 | 1490 | basic_block bb, *bbs; |
ca83d385 | 1491 | unsigned j, n_exits; |
9771b263 | 1492 | vec<edge> exits; |
992c31e6 | 1493 | struct tree_niter_desc niter_desc; |
ca83d385 | 1494 | edge ex; |
9c04723a DC |
1495 | struct nb_iter_bound *nb_iter; |
1496 | enum tree_code loop_bound_code = ERROR_MARK; | |
ecd4f20a | 1497 | tree loop_bound_step = NULL; |
9c04723a DC |
1498 | tree loop_bound_var = NULL; |
1499 | tree loop_iv_base = NULL; | |
538dd0b7 | 1500 | gcond *stmt = NULL; |
f1ebdfc5 | 1501 | |
ca83d385 | 1502 | exits = get_loop_exit_edges (loop); |
9771b263 | 1503 | n_exits = exits.length (); |
f481cd49 JH |
1504 | if (!n_exits) |
1505 | { | |
9771b263 | 1506 | exits.release (); |
f481cd49 JH |
1507 | continue; |
1508 | } | |
0dd0e980 | 1509 | |
9771b263 | 1510 | FOR_EACH_VEC_ELT (exits, j, ex) |
b6acab32 | 1511 | { |
992c31e6 | 1512 | tree niter = NULL; |
4839cb59 ZD |
1513 | HOST_WIDE_INT nitercst; |
1514 | int max = PARAM_VALUE (PARAM_MAX_PREDICTED_ITERATIONS); | |
1515 | int probability; | |
1516 | enum br_predictor predictor; | |
b6acab32 | 1517 | |
16fdb75f DC |
1518 | predict_extra_loop_exits (ex); |
1519 | ||
46deac6c | 1520 | if (number_of_iterations_exit (loop, ex, &niter_desc, false, false)) |
992c31e6 JH |
1521 | niter = niter_desc.niter; |
1522 | if (!niter || TREE_CODE (niter_desc.niter) != INTEGER_CST) | |
ca83d385 | 1523 | niter = loop_niter_by_eval (loop, ex); |
b6acab32 | 1524 | |
992c31e6 JH |
1525 | if (TREE_CODE (niter) == INTEGER_CST) |
1526 | { | |
cc269bb6 | 1527 | if (tree_fits_uhwi_p (niter) |
2aa579ad JJ |
1528 | && max |
1529 | && compare_tree_int (niter, max - 1) == -1) | |
ae7e9ddd | 1530 | nitercst = tree_to_uhwi (niter) + 1; |
992c31e6 | 1531 | else |
4839cb59 ZD |
1532 | nitercst = max; |
1533 | predictor = PRED_LOOP_ITERATIONS; | |
1534 | } | |
1535 | /* If we have just one exit and we can derive some information about | |
1536 | the number of iterations of the loop from the statements inside | |
1537 | the loop, use it to predict this exit. */ | |
1538 | else if (n_exits == 1) | |
1539 | { | |
652c4c71 | 1540 | nitercst = estimated_stmt_executions_int (loop); |
4839cb59 ZD |
1541 | if (nitercst < 0) |
1542 | continue; | |
1543 | if (nitercst > max) | |
1544 | nitercst = max; | |
b6acab32 | 1545 | |
4839cb59 | 1546 | predictor = PRED_LOOP_ITERATIONS_GUESSED; |
992c31e6 | 1547 | } |
4839cb59 ZD |
1548 | else |
1549 | continue; | |
1550 | ||
2aa579ad JJ |
1551 | /* If the prediction for number of iterations is zero, do not |
1552 | predict the exit edges. */ | |
1553 | if (nitercst == 0) | |
1554 | continue; | |
1555 | ||
4839cb59 ZD |
1556 | probability = ((REG_BR_PROB_BASE + nitercst / 2) / nitercst); |
1557 | predict_edge (ex, predictor, probability); | |
b6acab32 | 1558 | } |
9771b263 | 1559 | exits.release (); |
3d436d2a | 1560 | |
9c04723a DC |
1561 | /* Find information about loop bound variables. */ |
1562 | for (nb_iter = loop->bounds; nb_iter; | |
1563 | nb_iter = nb_iter->next) | |
1564 | if (nb_iter->stmt | |
1565 | && gimple_code (nb_iter->stmt) == GIMPLE_COND) | |
1566 | { | |
538dd0b7 | 1567 | stmt = as_a <gcond *> (nb_iter->stmt); |
9c04723a DC |
1568 | break; |
1569 | } | |
1570 | if (!stmt && last_stmt (loop->header) | |
1571 | && gimple_code (last_stmt (loop->header)) == GIMPLE_COND) | |
538dd0b7 | 1572 | stmt = as_a <gcond *> (last_stmt (loop->header)); |
9c04723a DC |
1573 | if (stmt) |
1574 | is_comparison_with_loop_invariant_p (stmt, loop, | |
1575 | &loop_bound_var, | |
1576 | &loop_bound_code, | |
1577 | &loop_bound_step, | |
1578 | &loop_iv_base); | |
1579 | ||
2ecfd709 | 1580 | bbs = get_loop_body (loop); |
6de9cd9a | 1581 | |
2ecfd709 ZD |
1582 | for (j = 0; j < loop->num_nodes; j++) |
1583 | { | |
1584 | int header_found = 0; | |
1585 | edge e; | |
628f6a4e | 1586 | edge_iterator ei; |
2ecfd709 ZD |
1587 | |
1588 | bb = bbs[j]; | |
bfdade77 | 1589 | |
969d70ca JH |
1590 | /* Bypass loop heuristics on continue statement. These |
1591 | statements construct loops via "non-loop" constructs | |
1592 | in the source language and are better to be handled | |
1593 | separately. */ | |
992c31e6 | 1594 | if (predicted_by_p (bb, PRED_CONTINUE)) |
969d70ca JH |
1595 | continue; |
1596 | ||
2ecfd709 ZD |
1597 | /* Loop branch heuristics - predict an edge back to a |
1598 | loop's head as taken. */ | |
9ff3d2de JL |
1599 | if (bb == loop->latch) |
1600 | { | |
1601 | e = find_edge (loop->latch, loop->header); | |
1602 | if (e) | |
1603 | { | |
1604 | header_found = 1; | |
1605 | predict_edge_def (e, PRED_LOOP_BRANCH, TAKEN); | |
1606 | } | |
1607 | } | |
bfdade77 | 1608 | |
2ecfd709 | 1609 | /* Loop exit heuristics - predict an edge exiting the loop if the |
d55d8fc7 | 1610 | conditional has no loop header successors as not taken. */ |
4839cb59 ZD |
1611 | if (!header_found |
1612 | /* If we already used more reliable loop exit predictors, do not | |
1613 | bother with PRED_LOOP_EXIT. */ | |
1614 | && !predicted_by_p (bb, PRED_LOOP_ITERATIONS_GUESSED) | |
1615 | && !predicted_by_p (bb, PRED_LOOP_ITERATIONS)) | |
2c9e13f3 JH |
1616 | { |
1617 | /* For loop with many exits we don't want to predict all exits | |
1618 | with the pretty large probability, because if all exits are | |
1619 | considered in row, the loop would be predicted to iterate | |
1620 | almost never. The code to divide probability by number of | |
1621 | exits is very rough. It should compute the number of exits | |
1622 | taken in each patch through function (not the overall number | |
1623 | of exits that might be a lot higher for loops with wide switch | |
1624 | statements in them) and compute n-th square root. | |
1625 | ||
1626 | We limit the minimal probability by 2% to avoid | |
1627 | EDGE_PROBABILITY_RELIABLE from trusting the branch prediction | |
1628 | as this was causing regression in perl benchmark containing such | |
1629 | a wide loop. */ | |
b8698a0f | 1630 | |
2c9e13f3 JH |
1631 | int probability = ((REG_BR_PROB_BASE |
1632 | - predictor_info [(int) PRED_LOOP_EXIT].hitrate) | |
1633 | / n_exits); | |
1634 | if (probability < HITRATE (2)) | |
1635 | probability = HITRATE (2); | |
1636 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1637 | if (e->dest->index < NUM_FIXED_BLOCKS | |
1638 | || !flow_bb_inside_loop_p (loop, e->dest)) | |
1639 | predict_edge (e, PRED_LOOP_EXIT, probability); | |
1640 | } | |
9c04723a DC |
1641 | if (loop_bound_var) |
1642 | predict_iv_comparison (loop, bb, loop_bound_var, loop_iv_base, | |
1643 | loop_bound_code, | |
9439e9a1 | 1644 | tree_to_shwi (loop_bound_step)); |
2ecfd709 | 1645 | } |
b8698a0f | 1646 | |
e0a21ab9 | 1647 | /* Free basic blocks from get_loop_body. */ |
36579663 | 1648 | free (bbs); |
f1ebdfc5 | 1649 | } |
6de9cd9a DN |
1650 | } |
1651 | ||
87022a6b JH |
1652 | /* Attempt to predict probabilities of BB outgoing edges using local |
1653 | properties. */ | |
1654 | static void | |
1655 | bb_estimate_probability_locally (basic_block bb) | |
1656 | { | |
9f215bf5 | 1657 | rtx_insn *last_insn = BB_END (bb); |
87022a6b JH |
1658 | rtx cond; |
1659 | ||
1660 | if (! can_predict_insn_p (last_insn)) | |
1661 | return; | |
1662 | cond = get_condition (last_insn, NULL, false, false); | |
1663 | if (! cond) | |
1664 | return; | |
1665 | ||
1666 | /* Try "pointer heuristic." | |
1667 | A comparison ptr == 0 is predicted as false. | |
1668 | Similarly, a comparison ptr1 == ptr2 is predicted as false. */ | |
1669 | if (COMPARISON_P (cond) | |
1670 | && ((REG_P (XEXP (cond, 0)) && REG_POINTER (XEXP (cond, 0))) | |
1671 | || (REG_P (XEXP (cond, 1)) && REG_POINTER (XEXP (cond, 1))))) | |
1672 | { | |
1673 | if (GET_CODE (cond) == EQ) | |
1674 | predict_insn_def (last_insn, PRED_POINTER, NOT_TAKEN); | |
1675 | else if (GET_CODE (cond) == NE) | |
1676 | predict_insn_def (last_insn, PRED_POINTER, TAKEN); | |
1677 | } | |
1678 | else | |
1679 | ||
1680 | /* Try "opcode heuristic." | |
1681 | EQ tests are usually false and NE tests are usually true. Also, | |
1682 | most quantities are positive, so we can make the appropriate guesses | |
1683 | about signed comparisons against zero. */ | |
1684 | switch (GET_CODE (cond)) | |
1685 | { | |
1686 | case CONST_INT: | |
1687 | /* Unconditional branch. */ | |
1688 | predict_insn_def (last_insn, PRED_UNCONDITIONAL, | |
1689 | cond == const0_rtx ? NOT_TAKEN : TAKEN); | |
1690 | break; | |
1691 | ||
1692 | case EQ: | |
1693 | case UNEQ: | |
1694 | /* Floating point comparisons appears to behave in a very | |
1695 | unpredictable way because of special role of = tests in | |
1696 | FP code. */ | |
1697 | if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0)))) | |
1698 | ; | |
1699 | /* Comparisons with 0 are often used for booleans and there is | |
1700 | nothing useful to predict about them. */ | |
1701 | else if (XEXP (cond, 1) == const0_rtx | |
1702 | || XEXP (cond, 0) == const0_rtx) | |
1703 | ; | |
1704 | else | |
1705 | predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, NOT_TAKEN); | |
1706 | break; | |
1707 | ||
1708 | case NE: | |
1709 | case LTGT: | |
1710 | /* Floating point comparisons appears to behave in a very | |
1711 | unpredictable way because of special role of = tests in | |
1712 | FP code. */ | |
1713 | if (FLOAT_MODE_P (GET_MODE (XEXP (cond, 0)))) | |
1714 | ; | |
1715 | /* Comparisons with 0 are often used for booleans and there is | |
1716 | nothing useful to predict about them. */ | |
1717 | else if (XEXP (cond, 1) == const0_rtx | |
1718 | || XEXP (cond, 0) == const0_rtx) | |
1719 | ; | |
1720 | else | |
1721 | predict_insn_def (last_insn, PRED_OPCODE_NONEQUAL, TAKEN); | |
1722 | break; | |
1723 | ||
1724 | case ORDERED: | |
1725 | predict_insn_def (last_insn, PRED_FPOPCODE, TAKEN); | |
1726 | break; | |
1727 | ||
1728 | case UNORDERED: | |
1729 | predict_insn_def (last_insn, PRED_FPOPCODE, NOT_TAKEN); | |
1730 | break; | |
1731 | ||
1732 | case LE: | |
1733 | case LT: | |
1734 | if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx | |
1735 | || XEXP (cond, 1) == constm1_rtx) | |
1736 | predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, NOT_TAKEN); | |
1737 | break; | |
1738 | ||
1739 | case GE: | |
1740 | case GT: | |
1741 | if (XEXP (cond, 1) == const0_rtx || XEXP (cond, 1) == const1_rtx | |
1742 | || XEXP (cond, 1) == constm1_rtx) | |
1743 | predict_insn_def (last_insn, PRED_OPCODE_POSITIVE, TAKEN); | |
1744 | break; | |
1745 | ||
1746 | default: | |
1747 | break; | |
1748 | } | |
1749 | } | |
1750 | ||
229031d0 | 1751 | /* Set edge->probability for each successor edge of BB. */ |
87022a6b JH |
1752 | void |
1753 | guess_outgoing_edge_probabilities (basic_block bb) | |
1754 | { | |
1755 | bb_estimate_probability_locally (bb); | |
1756 | combine_predictions_for_insn (BB_END (bb), bb); | |
1757 | } | |
6de9cd9a | 1758 | \f |
ed9c79e1 | 1759 | static tree expr_expected_value (tree, bitmap, enum br_predictor *predictor); |
726a989a RB |
1760 | |
1761 | /* Helper function for expr_expected_value. */ | |
42f97fd2 JH |
1762 | |
1763 | static tree | |
c08472ea | 1764 | expr_expected_value_1 (tree type, tree op0, enum tree_code code, |
ed9c79e1 | 1765 | tree op1, bitmap visited, enum br_predictor *predictor) |
42f97fd2 | 1766 | { |
726a989a RB |
1767 | gimple def; |
1768 | ||
ed9c79e1 JJ |
1769 | if (predictor) |
1770 | *predictor = PRED_UNCONDITIONAL; | |
1771 | ||
726a989a | 1772 | if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS) |
42f97fd2 | 1773 | { |
726a989a RB |
1774 | if (TREE_CONSTANT (op0)) |
1775 | return op0; | |
1776 | ||
1777 | if (code != SSA_NAME) | |
1778 | return NULL_TREE; | |
1779 | ||
1780 | def = SSA_NAME_DEF_STMT (op0); | |
42f97fd2 JH |
1781 | |
1782 | /* If we were already here, break the infinite cycle. */ | |
fcaa4ca4 | 1783 | if (!bitmap_set_bit (visited, SSA_NAME_VERSION (op0))) |
42f97fd2 | 1784 | return NULL; |
42f97fd2 | 1785 | |
726a989a | 1786 | if (gimple_code (def) == GIMPLE_PHI) |
42f97fd2 JH |
1787 | { |
1788 | /* All the arguments of the PHI node must have the same constant | |
1789 | length. */ | |
726a989a | 1790 | int i, n = gimple_phi_num_args (def); |
42f97fd2 | 1791 | tree val = NULL, new_val; |
6de9cd9a | 1792 | |
726a989a | 1793 | for (i = 0; i < n; i++) |
42f97fd2 JH |
1794 | { |
1795 | tree arg = PHI_ARG_DEF (def, i); | |
ed9c79e1 | 1796 | enum br_predictor predictor2; |
42f97fd2 JH |
1797 | |
1798 | /* If this PHI has itself as an argument, we cannot | |
1799 | determine the string length of this argument. However, | |
1f838355 | 1800 | if we can find an expected constant value for the other |
42f97fd2 JH |
1801 | PHI args then we can still be sure that this is |
1802 | likely a constant. So be optimistic and just | |
1803 | continue with the next argument. */ | |
1804 | if (arg == PHI_RESULT (def)) | |
1805 | continue; | |
1806 | ||
ed9c79e1 JJ |
1807 | new_val = expr_expected_value (arg, visited, &predictor2); |
1808 | ||
1809 | /* It is difficult to combine value predictors. Simply assume | |
1810 | that later predictor is weaker and take its prediction. */ | |
1811 | if (predictor && *predictor < predictor2) | |
1812 | *predictor = predictor2; | |
42f97fd2 JH |
1813 | if (!new_val) |
1814 | return NULL; | |
1815 | if (!val) | |
1816 | val = new_val; | |
1817 | else if (!operand_equal_p (val, new_val, false)) | |
1818 | return NULL; | |
1819 | } | |
1820 | return val; | |
1821 | } | |
726a989a | 1822 | if (is_gimple_assign (def)) |
42f97fd2 | 1823 | { |
726a989a RB |
1824 | if (gimple_assign_lhs (def) != op0) |
1825 | return NULL; | |
42f97fd2 | 1826 | |
726a989a RB |
1827 | return expr_expected_value_1 (TREE_TYPE (gimple_assign_lhs (def)), |
1828 | gimple_assign_rhs1 (def), | |
1829 | gimple_assign_rhs_code (def), | |
1830 | gimple_assign_rhs2 (def), | |
ed9c79e1 | 1831 | visited, predictor); |
726a989a RB |
1832 | } |
1833 | ||
1834 | if (is_gimple_call (def)) | |
1835 | { | |
1836 | tree decl = gimple_call_fndecl (def); | |
1837 | if (!decl) | |
ed9c79e1 JJ |
1838 | { |
1839 | if (gimple_call_internal_p (def) | |
1840 | && gimple_call_internal_fn (def) == IFN_BUILTIN_EXPECT) | |
1841 | { | |
1842 | gcc_assert (gimple_call_num_args (def) == 3); | |
1843 | tree val = gimple_call_arg (def, 0); | |
1844 | if (TREE_CONSTANT (val)) | |
1845 | return val; | |
1846 | if (predictor) | |
1847 | { | |
ed9c79e1 JJ |
1848 | tree val2 = gimple_call_arg (def, 2); |
1849 | gcc_assert (TREE_CODE (val2) == INTEGER_CST | |
1850 | && tree_fits_uhwi_p (val2) | |
1851 | && tree_to_uhwi (val2) < END_PREDICTORS); | |
1852 | *predictor = (enum br_predictor) tree_to_uhwi (val2); | |
1853 | } | |
1854 | return gimple_call_arg (def, 1); | |
1855 | } | |
1856 | return NULL; | |
1857 | } | |
c08472ea RH |
1858 | if (DECL_BUILT_IN_CLASS (decl) == BUILT_IN_NORMAL) |
1859 | switch (DECL_FUNCTION_CODE (decl)) | |
1860 | { | |
1861 | case BUILT_IN_EXPECT: | |
1862 | { | |
1863 | tree val; | |
1864 | if (gimple_call_num_args (def) != 2) | |
1865 | return NULL; | |
1866 | val = gimple_call_arg (def, 0); | |
1867 | if (TREE_CONSTANT (val)) | |
1868 | return val; | |
ed9c79e1 JJ |
1869 | if (predictor) |
1870 | *predictor = PRED_BUILTIN_EXPECT; | |
c08472ea RH |
1871 | return gimple_call_arg (def, 1); |
1872 | } | |
726a989a | 1873 | |
c08472ea RH |
1874 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_N: |
1875 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_1: | |
1876 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_2: | |
1877 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_4: | |
1878 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_8: | |
1879 | case BUILT_IN_SYNC_BOOL_COMPARE_AND_SWAP_16: | |
1880 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE: | |
1881 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_N: | |
1882 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_1: | |
1883 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_2: | |
1884 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_4: | |
1885 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_8: | |
1886 | case BUILT_IN_ATOMIC_COMPARE_EXCHANGE_16: | |
1887 | /* Assume that any given atomic operation has low contention, | |
1888 | and thus the compare-and-swap operation succeeds. */ | |
ed9c79e1 JJ |
1889 | if (predictor) |
1890 | *predictor = PRED_COMPARE_AND_SWAP; | |
c08472ea | 1891 | return boolean_true_node; |
083e891e MP |
1892 | default: |
1893 | break; | |
726a989a | 1894 | } |
42f97fd2 | 1895 | } |
726a989a RB |
1896 | |
1897 | return NULL; | |
42f97fd2 | 1898 | } |
726a989a RB |
1899 | |
1900 | if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS) | |
42f97fd2 | 1901 | { |
726a989a | 1902 | tree res; |
ed9c79e1 JJ |
1903 | enum br_predictor predictor2; |
1904 | op0 = expr_expected_value (op0, visited, predictor); | |
42f97fd2 JH |
1905 | if (!op0) |
1906 | return NULL; | |
ed9c79e1 JJ |
1907 | op1 = expr_expected_value (op1, visited, &predictor2); |
1908 | if (predictor && *predictor < predictor2) | |
1909 | *predictor = predictor2; | |
42f97fd2 JH |
1910 | if (!op1) |
1911 | return NULL; | |
726a989a | 1912 | res = fold_build2 (code, type, op0, op1); |
42f97fd2 JH |
1913 | if (TREE_CONSTANT (res)) |
1914 | return res; | |
1915 | return NULL; | |
1916 | } | |
726a989a | 1917 | if (get_gimple_rhs_class (code) == GIMPLE_UNARY_RHS) |
42f97fd2 | 1918 | { |
726a989a | 1919 | tree res; |
ed9c79e1 | 1920 | op0 = expr_expected_value (op0, visited, predictor); |
42f97fd2 JH |
1921 | if (!op0) |
1922 | return NULL; | |
726a989a | 1923 | res = fold_build1 (code, type, op0); |
42f97fd2 JH |
1924 | if (TREE_CONSTANT (res)) |
1925 | return res; | |
1926 | return NULL; | |
1927 | } | |
1928 | return NULL; | |
1929 | } | |
726a989a | 1930 | |
b8698a0f | 1931 | /* Return constant EXPR will likely have at execution time, NULL if unknown. |
726a989a RB |
1932 | The function is used by builtin_expect branch predictor so the evidence |
1933 | must come from this construct and additional possible constant folding. | |
b8698a0f | 1934 | |
726a989a RB |
1935 | We may want to implement more involved value guess (such as value range |
1936 | propagation based prediction), but such tricks shall go to new | |
1937 | implementation. */ | |
1938 | ||
1939 | static tree | |
ed9c79e1 JJ |
1940 | expr_expected_value (tree expr, bitmap visited, |
1941 | enum br_predictor *predictor) | |
726a989a RB |
1942 | { |
1943 | enum tree_code code; | |
1944 | tree op0, op1; | |
1945 | ||
1946 | if (TREE_CONSTANT (expr)) | |
ed9c79e1 JJ |
1947 | { |
1948 | if (predictor) | |
1949 | *predictor = PRED_UNCONDITIONAL; | |
1950 | return expr; | |
1951 | } | |
726a989a RB |
1952 | |
1953 | extract_ops_from_tree (expr, &code, &op0, &op1); | |
1954 | return expr_expected_value_1 (TREE_TYPE (expr), | |
ed9c79e1 | 1955 | op0, code, op1, visited, predictor); |
726a989a | 1956 | } |
42f97fd2 | 1957 | \f |
6de9cd9a DN |
1958 | /* Predict using opcode of the last statement in basic block. */ |
1959 | static void | |
1960 | tree_predict_by_opcode (basic_block bb) | |
1961 | { | |
726a989a | 1962 | gimple stmt = last_stmt (bb); |
6de9cd9a | 1963 | edge then_edge; |
726a989a | 1964 | tree op0, op1; |
6de9cd9a | 1965 | tree type; |
42f97fd2 | 1966 | tree val; |
726a989a | 1967 | enum tree_code cmp; |
42f97fd2 | 1968 | bitmap visited; |
628f6a4e | 1969 | edge_iterator ei; |
ed9c79e1 | 1970 | enum br_predictor predictor; |
6de9cd9a | 1971 | |
726a989a | 1972 | if (!stmt || gimple_code (stmt) != GIMPLE_COND) |
6de9cd9a | 1973 | return; |
628f6a4e | 1974 | FOR_EACH_EDGE (then_edge, ei, bb->succs) |
6de9cd9a | 1975 | if (then_edge->flags & EDGE_TRUE_VALUE) |
628f6a4e | 1976 | break; |
726a989a RB |
1977 | op0 = gimple_cond_lhs (stmt); |
1978 | op1 = gimple_cond_rhs (stmt); | |
1979 | cmp = gimple_cond_code (stmt); | |
6de9cd9a | 1980 | type = TREE_TYPE (op0); |
8bdbfff5 | 1981 | visited = BITMAP_ALLOC (NULL); |
ed9c79e1 JJ |
1982 | val = expr_expected_value_1 (boolean_type_node, op0, cmp, op1, visited, |
1983 | &predictor); | |
8bdbfff5 | 1984 | BITMAP_FREE (visited); |
ed9c79e1 | 1985 | if (val && TREE_CODE (val) == INTEGER_CST) |
42f97fd2 | 1986 | { |
ed9c79e1 JJ |
1987 | if (predictor == PRED_BUILTIN_EXPECT) |
1988 | { | |
1989 | int percent = PARAM_VALUE (BUILTIN_EXPECT_PROBABILITY); | |
942df739 | 1990 | |
ed9c79e1 JJ |
1991 | gcc_assert (percent >= 0 && percent <= 100); |
1992 | if (integer_zerop (val)) | |
1993 | percent = 100 - percent; | |
1994 | predict_edge (then_edge, PRED_BUILTIN_EXPECT, HITRATE (percent)); | |
1995 | } | |
1996 | else | |
1997 | predict_edge (then_edge, predictor, | |
1998 | integer_zerop (val) ? NOT_TAKEN : TAKEN); | |
42f97fd2 | 1999 | } |
6de9cd9a DN |
2000 | /* Try "pointer heuristic." |
2001 | A comparison ptr == 0 is predicted as false. | |
2002 | Similarly, a comparison ptr1 == ptr2 is predicted as false. */ | |
2003 | if (POINTER_TYPE_P (type)) | |
2004 | { | |
726a989a | 2005 | if (cmp == EQ_EXPR) |
6de9cd9a | 2006 | predict_edge_def (then_edge, PRED_TREE_POINTER, NOT_TAKEN); |
726a989a | 2007 | else if (cmp == NE_EXPR) |
6de9cd9a DN |
2008 | predict_edge_def (then_edge, PRED_TREE_POINTER, TAKEN); |
2009 | } | |
2010 | else | |
2011 | ||
2012 | /* Try "opcode heuristic." | |
2013 | EQ tests are usually false and NE tests are usually true. Also, | |
2014 | most quantities are positive, so we can make the appropriate guesses | |
2015 | about signed comparisons against zero. */ | |
726a989a | 2016 | switch (cmp) |
6de9cd9a DN |
2017 | { |
2018 | case EQ_EXPR: | |
2019 | case UNEQ_EXPR: | |
2020 | /* Floating point comparisons appears to behave in a very | |
2021 | unpredictable way because of special role of = tests in | |
2022 | FP code. */ | |
2023 | if (FLOAT_TYPE_P (type)) | |
2024 | ; | |
2025 | /* Comparisons with 0 are often used for booleans and there is | |
2026 | nothing useful to predict about them. */ | |
726a989a | 2027 | else if (integer_zerop (op0) || integer_zerop (op1)) |
6de9cd9a DN |
2028 | ; |
2029 | else | |
2030 | predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, NOT_TAKEN); | |
2031 | break; | |
2032 | ||
2033 | case NE_EXPR: | |
d1a7edaf | 2034 | case LTGT_EXPR: |
6de9cd9a DN |
2035 | /* Floating point comparisons appears to behave in a very |
2036 | unpredictable way because of special role of = tests in | |
2037 | FP code. */ | |
2038 | if (FLOAT_TYPE_P (type)) | |
2039 | ; | |
2040 | /* Comparisons with 0 are often used for booleans and there is | |
2041 | nothing useful to predict about them. */ | |
2042 | else if (integer_zerop (op0) | |
726a989a | 2043 | || integer_zerop (op1)) |
6de9cd9a DN |
2044 | ; |
2045 | else | |
2046 | predict_edge_def (then_edge, PRED_TREE_OPCODE_NONEQUAL, TAKEN); | |
2047 | break; | |
2048 | ||
2049 | case ORDERED_EXPR: | |
2050 | predict_edge_def (then_edge, PRED_TREE_FPOPCODE, TAKEN); | |
2051 | break; | |
2052 | ||
2053 | case UNORDERED_EXPR: | |
2054 | predict_edge_def (then_edge, PRED_TREE_FPOPCODE, NOT_TAKEN); | |
2055 | break; | |
2056 | ||
2057 | case LE_EXPR: | |
2058 | case LT_EXPR: | |
726a989a RB |
2059 | if (integer_zerop (op1) |
2060 | || integer_onep (op1) | |
2061 | || integer_all_onesp (op1) | |
2062 | || real_zerop (op1) | |
2063 | || real_onep (op1) | |
2064 | || real_minus_onep (op1)) | |
6de9cd9a DN |
2065 | predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, NOT_TAKEN); |
2066 | break; | |
2067 | ||
2068 | case GE_EXPR: | |
2069 | case GT_EXPR: | |
726a989a RB |
2070 | if (integer_zerop (op1) |
2071 | || integer_onep (op1) | |
2072 | || integer_all_onesp (op1) | |
2073 | || real_zerop (op1) | |
2074 | || real_onep (op1) | |
2075 | || real_minus_onep (op1)) | |
6de9cd9a DN |
2076 | predict_edge_def (then_edge, PRED_TREE_OPCODE_POSITIVE, TAKEN); |
2077 | break; | |
2078 | ||
2079 | default: | |
2080 | break; | |
2081 | } | |
2082 | } | |
2083 | ||
bb033fd8 | 2084 | /* Try to guess whether the value of return means error code. */ |
726a989a | 2085 | |
bb033fd8 JH |
2086 | static enum br_predictor |
2087 | return_prediction (tree val, enum prediction *prediction) | |
2088 | { | |
2089 | /* VOID. */ | |
2090 | if (!val) | |
2091 | return PRED_NO_PREDICTION; | |
2092 | /* Different heuristics for pointers and scalars. */ | |
2093 | if (POINTER_TYPE_P (TREE_TYPE (val))) | |
2094 | { | |
2095 | /* NULL is usually not returned. */ | |
2096 | if (integer_zerop (val)) | |
2097 | { | |
2098 | *prediction = NOT_TAKEN; | |
2099 | return PRED_NULL_RETURN; | |
2100 | } | |
2101 | } | |
2102 | else if (INTEGRAL_TYPE_P (TREE_TYPE (val))) | |
2103 | { | |
2104 | /* Negative return values are often used to indicate | |
2105 | errors. */ | |
2106 | if (TREE_CODE (val) == INTEGER_CST | |
2107 | && tree_int_cst_sgn (val) < 0) | |
2108 | { | |
2109 | *prediction = NOT_TAKEN; | |
2110 | return PRED_NEGATIVE_RETURN; | |
2111 | } | |
2112 | /* Constant return values seems to be commonly taken. | |
2113 | Zero/one often represent booleans so exclude them from the | |
2114 | heuristics. */ | |
2115 | if (TREE_CONSTANT (val) | |
2116 | && (!integer_zerop (val) && !integer_onep (val))) | |
2117 | { | |
2118 | *prediction = TAKEN; | |
75b6bb62 | 2119 | return PRED_CONST_RETURN; |
bb033fd8 JH |
2120 | } |
2121 | } | |
2122 | return PRED_NO_PREDICTION; | |
2123 | } | |
2124 | ||
2125 | /* Find the basic block with return expression and look up for possible | |
2126 | return value trying to apply RETURN_PREDICTION heuristics. */ | |
2127 | static void | |
3e4b9ad0 | 2128 | apply_return_prediction (void) |
bb033fd8 | 2129 | { |
538dd0b7 | 2130 | greturn *return_stmt = NULL; |
bb033fd8 JH |
2131 | tree return_val; |
2132 | edge e; | |
538dd0b7 | 2133 | gphi *phi; |
bb033fd8 JH |
2134 | int phi_num_args, i; |
2135 | enum br_predictor pred; | |
2136 | enum prediction direction; | |
628f6a4e | 2137 | edge_iterator ei; |
bb033fd8 | 2138 | |
fefa31b5 | 2139 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) |
bb033fd8 | 2140 | { |
538dd0b7 DM |
2141 | gimple last = last_stmt (e->src); |
2142 | if (last | |
2143 | && gimple_code (last) == GIMPLE_RETURN) | |
2144 | { | |
2145 | return_stmt = as_a <greturn *> (last); | |
2146 | break; | |
2147 | } | |
bb033fd8 JH |
2148 | } |
2149 | if (!e) | |
2150 | return; | |
726a989a | 2151 | return_val = gimple_return_retval (return_stmt); |
bb033fd8 JH |
2152 | if (!return_val) |
2153 | return; | |
bb033fd8 JH |
2154 | if (TREE_CODE (return_val) != SSA_NAME |
2155 | || !SSA_NAME_DEF_STMT (return_val) | |
726a989a | 2156 | || gimple_code (SSA_NAME_DEF_STMT (return_val)) != GIMPLE_PHI) |
bb033fd8 | 2157 | return; |
538dd0b7 | 2158 | phi = as_a <gphi *> (SSA_NAME_DEF_STMT (return_val)); |
726a989a | 2159 | phi_num_args = gimple_phi_num_args (phi); |
bb033fd8 JH |
2160 | pred = return_prediction (PHI_ARG_DEF (phi, 0), &direction); |
2161 | ||
2162 | /* Avoid the degenerate case where all return values form the function | |
2163 | belongs to same category (ie they are all positive constants) | |
2164 | so we can hardly say something about them. */ | |
2165 | for (i = 1; i < phi_num_args; i++) | |
2166 | if (pred != return_prediction (PHI_ARG_DEF (phi, i), &direction)) | |
2167 | break; | |
2168 | if (i != phi_num_args) | |
2169 | for (i = 0; i < phi_num_args; i++) | |
2170 | { | |
2171 | pred = return_prediction (PHI_ARG_DEF (phi, i), &direction); | |
2172 | if (pred != PRED_NO_PREDICTION) | |
5210bbc5 JH |
2173 | predict_paths_leading_to_edge (gimple_phi_arg_edge (phi, i), pred, |
2174 | direction); | |
bb033fd8 JH |
2175 | } |
2176 | } | |
2177 | ||
2178 | /* Look for basic block that contains unlikely to happen events | |
2179 | (such as noreturn calls) and mark all paths leading to execution | |
2180 | of this basic blocks as unlikely. */ | |
2181 | ||
2182 | static void | |
2183 | tree_bb_level_predictions (void) | |
2184 | { | |
2185 | basic_block bb; | |
c0ee0021 JH |
2186 | bool has_return_edges = false; |
2187 | edge e; | |
2188 | edge_iterator ei; | |
2189 | ||
fefa31b5 | 2190 | FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) |
c0ee0021 JH |
2191 | if (!(e->flags & (EDGE_ABNORMAL | EDGE_FAKE | EDGE_EH))) |
2192 | { | |
2193 | has_return_edges = true; | |
2194 | break; | |
2195 | } | |
bb033fd8 | 2196 | |
3e4b9ad0 | 2197 | apply_return_prediction (); |
bb033fd8 | 2198 | |
11cd3bed | 2199 | FOR_EACH_BB_FN (bb, cfun) |
bb033fd8 | 2200 | { |
726a989a | 2201 | gimple_stmt_iterator gsi; |
bb033fd8 | 2202 | |
7299cb99 | 2203 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) |
bb033fd8 | 2204 | { |
726a989a | 2205 | gimple stmt = gsi_stmt (gsi); |
52bf96d2 | 2206 | tree decl; |
daac0317 | 2207 | |
726a989a | 2208 | if (is_gimple_call (stmt)) |
bb033fd8 | 2209 | { |
c0ee0021 JH |
2210 | if ((gimple_call_flags (stmt) & ECF_NORETURN) |
2211 | && has_return_edges) | |
726a989a RB |
2212 | predict_paths_leading_to (bb, PRED_NORETURN, |
2213 | NOT_TAKEN); | |
2214 | decl = gimple_call_fndecl (stmt); | |
2215 | if (decl | |
2216 | && lookup_attribute ("cold", | |
2217 | DECL_ATTRIBUTES (decl))) | |
2218 | predict_paths_leading_to (bb, PRED_COLD_FUNCTION, | |
2219 | NOT_TAKEN); | |
bb033fd8 | 2220 | } |
726a989a RB |
2221 | else if (gimple_code (stmt) == GIMPLE_PREDICT) |
2222 | { | |
2223 | predict_paths_leading_to (bb, gimple_predict_predictor (stmt), | |
2224 | gimple_predict_outcome (stmt)); | |
7299cb99 JH |
2225 | /* Keep GIMPLE_PREDICT around so early inlining will propagate |
2226 | hints to callers. */ | |
726a989a | 2227 | } |
bb033fd8 JH |
2228 | } |
2229 | } | |
bb033fd8 JH |
2230 | } |
2231 | ||
f06b0a10 ZD |
2232 | #ifdef ENABLE_CHECKING |
2233 | ||
b787e7a2 | 2234 | /* Callback for hash_map::traverse, asserts that the pointer map is |
f06b0a10 ZD |
2235 | empty. */ |
2236 | ||
b787e7a2 TS |
2237 | bool |
2238 | assert_is_empty (const_basic_block const &, edge_prediction *const &value, | |
2239 | void *) | |
f06b0a10 | 2240 | { |
b787e7a2 | 2241 | gcc_assert (!value); |
f06b0a10 ZD |
2242 | return false; |
2243 | } | |
2244 | #endif | |
2245 | ||
8e88f9fd SP |
2246 | /* Predict branch probabilities and estimate profile for basic block BB. */ |
2247 | ||
2248 | static void | |
2249 | tree_estimate_probability_bb (basic_block bb) | |
2250 | { | |
2251 | edge e; | |
2252 | edge_iterator ei; | |
2253 | gimple last; | |
2254 | ||
2255 | FOR_EACH_EDGE (e, ei, bb->succs) | |
2256 | { | |
e45abe1f | 2257 | /* Predict edges to user labels with attributes. */ |
fefa31b5 | 2258 | if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)) |
e45abe1f RH |
2259 | { |
2260 | gimple_stmt_iterator gi; | |
2261 | for (gi = gsi_start_bb (e->dest); !gsi_end_p (gi); gsi_next (&gi)) | |
2262 | { | |
538dd0b7 | 2263 | glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gi)); |
e45abe1f RH |
2264 | tree decl; |
2265 | ||
538dd0b7 | 2266 | if (!label_stmt) |
e45abe1f | 2267 | break; |
538dd0b7 | 2268 | decl = gimple_label_label (label_stmt); |
e45abe1f RH |
2269 | if (DECL_ARTIFICIAL (decl)) |
2270 | continue; | |
2271 | ||
2272 | /* Finally, we have a user-defined label. */ | |
2273 | if (lookup_attribute ("cold", DECL_ATTRIBUTES (decl))) | |
2274 | predict_edge_def (e, PRED_COLD_LABEL, NOT_TAKEN); | |
2275 | else if (lookup_attribute ("hot", DECL_ATTRIBUTES (decl))) | |
2276 | predict_edge_def (e, PRED_HOT_LABEL, TAKEN); | |
2277 | } | |
2278 | } | |
2279 | ||
8e88f9fd SP |
2280 | /* Predict early returns to be probable, as we've already taken |
2281 | care for error returns and other cases are often used for | |
2282 | fast paths through function. | |
2283 | ||
2284 | Since we've already removed the return statements, we are | |
2285 | looking for CFG like: | |
2286 | ||
2287 | if (conditional) | |
2288 | { | |
2289 | .. | |
2290 | goto return_block | |
2291 | } | |
2292 | some other blocks | |
2293 | return_block: | |
2294 | return_stmt. */ | |
2295 | if (e->dest != bb->next_bb | |
fefa31b5 | 2296 | && e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) |
8e88f9fd | 2297 | && single_succ_p (e->dest) |
fefa31b5 | 2298 | && single_succ_edge (e->dest)->dest == EXIT_BLOCK_PTR_FOR_FN (cfun) |
8e88f9fd SP |
2299 | && (last = last_stmt (e->dest)) != NULL |
2300 | && gimple_code (last) == GIMPLE_RETURN) | |
2301 | { | |
2302 | edge e1; | |
2303 | edge_iterator ei1; | |
2304 | ||
2305 | if (single_succ_p (bb)) | |
2306 | { | |
2307 | FOR_EACH_EDGE (e1, ei1, bb->preds) | |
2308 | if (!predicted_by_p (e1->src, PRED_NULL_RETURN) | |
2309 | && !predicted_by_p (e1->src, PRED_CONST_RETURN) | |
2310 | && !predicted_by_p (e1->src, PRED_NEGATIVE_RETURN)) | |
2311 | predict_edge_def (e1, PRED_TREE_EARLY_RETURN, NOT_TAKEN); | |
2312 | } | |
2313 | else | |
2314 | if (!predicted_by_p (e->src, PRED_NULL_RETURN) | |
2315 | && !predicted_by_p (e->src, PRED_CONST_RETURN) | |
2316 | && !predicted_by_p (e->src, PRED_NEGATIVE_RETURN)) | |
2317 | predict_edge_def (e, PRED_TREE_EARLY_RETURN, NOT_TAKEN); | |
2318 | } | |
2319 | ||
2320 | /* Look for block we are guarding (ie we dominate it, | |
2321 | but it doesn't postdominate us). */ | |
fefa31b5 | 2322 | if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun) && e->dest != bb |
8e88f9fd SP |
2323 | && dominated_by_p (CDI_DOMINATORS, e->dest, e->src) |
2324 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e->dest)) | |
2325 | { | |
2326 | gimple_stmt_iterator bi; | |
2327 | ||
2328 | /* The call heuristic claims that a guarded function call | |
2329 | is improbable. This is because such calls are often used | |
2330 | to signal exceptional situations such as printing error | |
2331 | messages. */ | |
2332 | for (bi = gsi_start_bb (e->dest); !gsi_end_p (bi); | |
2333 | gsi_next (&bi)) | |
2334 | { | |
2335 | gimple stmt = gsi_stmt (bi); | |
2336 | if (is_gimple_call (stmt) | |
2337 | /* Constant and pure calls are hardly used to signalize | |
2338 | something exceptional. */ | |
2339 | && gimple_has_side_effects (stmt)) | |
2340 | { | |
2341 | predict_edge_def (e, PRED_CALL, NOT_TAKEN); | |
2342 | break; | |
2343 | } | |
2344 | } | |
2345 | } | |
2346 | } | |
2347 | tree_predict_by_opcode (bb); | |
2348 | } | |
2349 | ||
2350 | /* Predict branch probabilities and estimate profile of the tree CFG. | |
2351 | This function can be called from the loop optimizers to recompute | |
2352 | the profile information. */ | |
2353 | ||
2354 | void | |
6de9cd9a DN |
2355 | tree_estimate_probability (void) |
2356 | { | |
2357 | basic_block bb; | |
6de9cd9a | 2358 | |
bb033fd8 | 2359 | add_noreturn_fake_exit_edges (); |
6de9cd9a | 2360 | connect_infinite_loops_to_exit (); |
c7b852c8 ZD |
2361 | /* We use loop_niter_by_eval, which requires that the loops have |
2362 | preheaders. */ | |
2363 | create_preheaders (CP_SIMPLE_PREHEADERS); | |
6de9cd9a DN |
2364 | calculate_dominance_info (CDI_POST_DOMINATORS); |
2365 | ||
b787e7a2 | 2366 | bb_predictions = new hash_map<const_basic_block, edge_prediction *>; |
bb033fd8 | 2367 | tree_bb_level_predictions (); |
4839cb59 | 2368 | record_loop_exits (); |
8e88f9fd | 2369 | |
0fc822d0 | 2370 | if (number_of_loops (cfun) > 1) |
d73be268 | 2371 | predict_loops (); |
6de9cd9a | 2372 | |
11cd3bed | 2373 | FOR_EACH_BB_FN (bb, cfun) |
8e88f9fd | 2374 | tree_estimate_probability_bb (bb); |
6de9cd9a | 2375 | |
11cd3bed | 2376 | FOR_EACH_BB_FN (bb, cfun) |
10d22567 | 2377 | combine_predictions_for_bb (bb); |
861f9cd0 | 2378 | |
f06b0a10 | 2379 | #ifdef ENABLE_CHECKING |
b787e7a2 | 2380 | bb_predictions->traverse<void *, assert_is_empty> (NULL); |
f06b0a10 | 2381 | #endif |
b787e7a2 | 2382 | delete bb_predictions; |
f06b0a10 ZD |
2383 | bb_predictions = NULL; |
2384 | ||
67fa7880 | 2385 | estimate_bb_frequencies (false); |
6de9cd9a | 2386 | free_dominance_info (CDI_POST_DOMINATORS); |
6809cbf9 | 2387 | remove_fake_exit_edges (); |
8e88f9fd | 2388 | } |
994a57cd | 2389 | \f |
fa10beec | 2390 | /* Predict edges to successors of CUR whose sources are not postdominated by |
3e4b9ad0 | 2391 | BB by PRED and recurse to all postdominators. */ |
bb033fd8 JH |
2392 | |
2393 | static void | |
3e4b9ad0 JH |
2394 | predict_paths_for_bb (basic_block cur, basic_block bb, |
2395 | enum br_predictor pred, | |
0f3b7e9a JH |
2396 | enum prediction taken, |
2397 | bitmap visited) | |
bb033fd8 JH |
2398 | { |
2399 | edge e; | |
628f6a4e | 2400 | edge_iterator ei; |
3e4b9ad0 | 2401 | basic_block son; |
bb033fd8 | 2402 | |
3e4b9ad0 JH |
2403 | /* We are looking for all edges forming edge cut induced by |
2404 | set of all blocks postdominated by BB. */ | |
2405 | FOR_EACH_EDGE (e, ei, cur->preds) | |
2406 | if (e->src->index >= NUM_FIXED_BLOCKS | |
2407 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, bb)) | |
bb033fd8 | 2408 | { |
450997ef JH |
2409 | edge e2; |
2410 | edge_iterator ei2; | |
2411 | bool found = false; | |
2412 | ||
5210bbc5 JH |
2413 | /* Ignore fake edges and eh, we predict them as not taken anyway. */ |
2414 | if (e->flags & (EDGE_EH | EDGE_FAKE)) | |
450997ef | 2415 | continue; |
3e4b9ad0 | 2416 | gcc_assert (bb == cur || dominated_by_p (CDI_POST_DOMINATORS, cur, bb)); |
450997ef | 2417 | |
0f3b7e9a | 2418 | /* See if there is an edge from e->src that is not abnormal |
450997ef JH |
2419 | and does not lead to BB. */ |
2420 | FOR_EACH_EDGE (e2, ei2, e->src->succs) | |
2421 | if (e2 != e | |
5210bbc5 | 2422 | && !(e2->flags & (EDGE_EH | EDGE_FAKE)) |
450997ef JH |
2423 | && !dominated_by_p (CDI_POST_DOMINATORS, e2->dest, bb)) |
2424 | { | |
2425 | found = true; | |
2426 | break; | |
2427 | } | |
2428 | ||
2429 | /* If there is non-abnormal path leaving e->src, predict edge | |
2430 | using predictor. Otherwise we need to look for paths | |
0f3b7e9a JH |
2431 | leading to e->src. |
2432 | ||
2433 | The second may lead to infinite loop in the case we are predicitng | |
2434 | regions that are only reachable by abnormal edges. We simply | |
2435 | prevent visiting given BB twice. */ | |
450997ef JH |
2436 | if (found) |
2437 | predict_edge_def (e, pred, taken); | |
993716bd | 2438 | else if (bitmap_set_bit (visited, e->src->index)) |
0f3b7e9a | 2439 | predict_paths_for_bb (e->src, e->src, pred, taken, visited); |
bb033fd8 | 2440 | } |
3e4b9ad0 JH |
2441 | for (son = first_dom_son (CDI_POST_DOMINATORS, cur); |
2442 | son; | |
2443 | son = next_dom_son (CDI_POST_DOMINATORS, son)) | |
0f3b7e9a | 2444 | predict_paths_for_bb (son, bb, pred, taken, visited); |
3e4b9ad0 | 2445 | } |
bb033fd8 | 2446 | |
3e4b9ad0 JH |
2447 | /* Sets branch probabilities according to PREDiction and |
2448 | FLAGS. */ | |
bb033fd8 | 2449 | |
3e4b9ad0 JH |
2450 | static void |
2451 | predict_paths_leading_to (basic_block bb, enum br_predictor pred, | |
2452 | enum prediction taken) | |
2453 | { | |
0f3b7e9a JH |
2454 | bitmap visited = BITMAP_ALLOC (NULL); |
2455 | predict_paths_for_bb (bb, bb, pred, taken, visited); | |
2456 | BITMAP_FREE (visited); | |
bb033fd8 | 2457 | } |
5210bbc5 JH |
2458 | |
2459 | /* Like predict_paths_leading_to but take edge instead of basic block. */ | |
2460 | ||
2461 | static void | |
2462 | predict_paths_leading_to_edge (edge e, enum br_predictor pred, | |
2463 | enum prediction taken) | |
2464 | { | |
2465 | bool has_nonloop_edge = false; | |
2466 | edge_iterator ei; | |
2467 | edge e2; | |
2468 | ||
2469 | basic_block bb = e->src; | |
2470 | FOR_EACH_EDGE (e2, ei, bb->succs) | |
2471 | if (e2->dest != e->src && e2->dest != e->dest | |
2472 | && !(e->flags & (EDGE_EH | EDGE_FAKE)) | |
2473 | && !dominated_by_p (CDI_POST_DOMINATORS, e->src, e2->dest)) | |
2474 | { | |
2475 | has_nonloop_edge = true; | |
2476 | break; | |
2477 | } | |
2478 | if (!has_nonloop_edge) | |
0f3b7e9a JH |
2479 | { |
2480 | bitmap visited = BITMAP_ALLOC (NULL); | |
2481 | predict_paths_for_bb (bb, bb, pred, taken, visited); | |
2482 | BITMAP_FREE (visited); | |
2483 | } | |
5210bbc5 JH |
2484 | else |
2485 | predict_edge_def (e, pred, taken); | |
2486 | } | |
969d70ca | 2487 | \f |
57cb6d52 | 2488 | /* This is used to carry information about basic blocks. It is |
861f9cd0 JH |
2489 | attached to the AUX field of the standard CFG block. */ |
2490 | ||
11478306 | 2491 | struct block_info |
861f9cd0 JH |
2492 | { |
2493 | /* Estimated frequency of execution of basic_block. */ | |
ac5e69da | 2494 | sreal frequency; |
861f9cd0 JH |
2495 | |
2496 | /* To keep queue of basic blocks to process. */ | |
2497 | basic_block next; | |
2498 | ||
eaec9b3d | 2499 | /* Number of predecessors we need to visit first. */ |
754d9299 | 2500 | int npredecessors; |
11478306 | 2501 | }; |
861f9cd0 JH |
2502 | |
2503 | /* Similar information for edges. */ | |
11478306 | 2504 | struct edge_prob_info |
861f9cd0 | 2505 | { |
569b7f6a | 2506 | /* In case edge is a loopback edge, the probability edge will be reached |
861f9cd0 | 2507 | in case header is. Estimated number of iterations of the loop can be |
8aa18a7d | 2508 | then computed as 1 / (1 - back_edge_prob). */ |
ac5e69da | 2509 | sreal back_edge_prob; |
569b7f6a | 2510 | /* True if the edge is a loopback edge in the natural loop. */ |
2c45a16a | 2511 | unsigned int back_edge:1; |
11478306 | 2512 | }; |
861f9cd0 | 2513 | |
11478306 | 2514 | #define BLOCK_INFO(B) ((block_info *) (B)->aux) |
59f2e9d8 | 2515 | #undef EDGE_INFO |
11478306 | 2516 | #define EDGE_INFO(E) ((edge_prob_info *) (E)->aux) |
861f9cd0 JH |
2517 | |
2518 | /* Helper function for estimate_bb_frequencies. | |
598ec7bd ZD |
2519 | Propagate the frequencies in blocks marked in |
2520 | TOVISIT, starting in HEAD. */ | |
bfdade77 | 2521 | |
861f9cd0 | 2522 | static void |
598ec7bd | 2523 | propagate_freq (basic_block head, bitmap tovisit) |
861f9cd0 | 2524 | { |
e0082a72 ZD |
2525 | basic_block bb; |
2526 | basic_block last; | |
b9af0016 | 2527 | unsigned i; |
861f9cd0 JH |
2528 | edge e; |
2529 | basic_block nextbb; | |
8a998e0c | 2530 | bitmap_iterator bi; |
247a370b | 2531 | |
eaec9b3d | 2532 | /* For each basic block we need to visit count number of his predecessors |
247a370b | 2533 | we need to visit first. */ |
8a998e0c | 2534 | EXECUTE_IF_SET_IN_BITMAP (tovisit, 0, i, bi) |
247a370b | 2535 | { |
8a998e0c JL |
2536 | edge_iterator ei; |
2537 | int count = 0; | |
2538 | ||
06e28de2 | 2539 | bb = BASIC_BLOCK_FOR_FN (cfun, i); |
bfdade77 | 2540 | |
8a998e0c JL |
2541 | FOR_EACH_EDGE (e, ei, bb->preds) |
2542 | { | |
2543 | bool visit = bitmap_bit_p (tovisit, e->src->index); | |
2544 | ||
2545 | if (visit && !(e->flags & EDGE_DFS_BACK)) | |
2546 | count++; | |
2547 | else if (visit && dump_file && !EDGE_INFO (e)->back_edge) | |
2548 | fprintf (dump_file, | |
2549 | "Irreducible region hit, ignoring edge to %i->%i\n", | |
2550 | e->src->index, bb->index); | |
247a370b | 2551 | } |
b9af0016 | 2552 | BLOCK_INFO (bb)->npredecessors = count; |
b35366ce | 2553 | /* When function never returns, we will never process exit block. */ |
fefa31b5 | 2554 | if (!count && bb == EXIT_BLOCK_PTR_FOR_FN (cfun)) |
b35366ce | 2555 | bb->count = bb->frequency = 0; |
247a370b | 2556 | } |
861f9cd0 | 2557 | |
fd27ffab | 2558 | BLOCK_INFO (head)->frequency = 1; |
e0082a72 ZD |
2559 | last = head; |
2560 | for (bb = head; bb; bb = nextbb) | |
861f9cd0 | 2561 | { |
628f6a4e | 2562 | edge_iterator ei; |
fd27ffab ML |
2563 | sreal cyclic_probability = 0; |
2564 | sreal frequency = 0; | |
861f9cd0 JH |
2565 | |
2566 | nextbb = BLOCK_INFO (bb)->next; | |
2567 | BLOCK_INFO (bb)->next = NULL; | |
2568 | ||
2569 | /* Compute frequency of basic block. */ | |
2570 | if (bb != head) | |
2571 | { | |
247a370b | 2572 | #ifdef ENABLE_CHECKING |
628f6a4e | 2573 | FOR_EACH_EDGE (e, ei, bb->preds) |
e16acfcd NS |
2574 | gcc_assert (!bitmap_bit_p (tovisit, e->src->index) |
2575 | || (e->flags & EDGE_DFS_BACK)); | |
247a370b | 2576 | #endif |
861f9cd0 | 2577 | |
628f6a4e | 2578 | FOR_EACH_EDGE (e, ei, bb->preds) |
861f9cd0 | 2579 | if (EDGE_INFO (e)->back_edge) |
8aa18a7d | 2580 | { |
618b7f29 | 2581 | cyclic_probability += EDGE_INFO (e)->back_edge_prob; |
8aa18a7d | 2582 | } |
247a370b | 2583 | else if (!(e->flags & EDGE_DFS_BACK)) |
8aa18a7d | 2584 | { |
8aa18a7d JH |
2585 | /* frequency += (e->probability |
2586 | * BLOCK_INFO (e->src)->frequency / | |
2587 | REG_BR_PROB_BASE); */ | |
2588 | ||
fd27ffab | 2589 | sreal tmp = e->probability; |
618b7f29 TS |
2590 | tmp *= BLOCK_INFO (e->src)->frequency; |
2591 | tmp *= real_inv_br_prob_base; | |
2592 | frequency += tmp; | |
8aa18a7d JH |
2593 | } |
2594 | ||
fd27ffab | 2595 | if (cyclic_probability == 0) |
ac5e69da | 2596 | { |
618b7f29 | 2597 | BLOCK_INFO (bb)->frequency = frequency; |
ac5e69da | 2598 | } |
fbe3b30b SB |
2599 | else |
2600 | { | |
618b7f29 TS |
2601 | if (cyclic_probability > real_almost_one) |
2602 | cyclic_probability = real_almost_one; | |
861f9cd0 | 2603 | |
79a490a9 | 2604 | /* BLOCK_INFO (bb)->frequency = frequency |
ac5e69da | 2605 | / (1 - cyclic_probability) */ |
861f9cd0 | 2606 | |
fd27ffab | 2607 | cyclic_probability = sreal (1) - cyclic_probability; |
618b7f29 | 2608 | BLOCK_INFO (bb)->frequency = frequency / cyclic_probability; |
fbe3b30b | 2609 | } |
861f9cd0 JH |
2610 | } |
2611 | ||
8a998e0c | 2612 | bitmap_clear_bit (tovisit, bb->index); |
861f9cd0 | 2613 | |
9ff3d2de JL |
2614 | e = find_edge (bb, head); |
2615 | if (e) | |
2616 | { | |
9ff3d2de JL |
2617 | /* EDGE_INFO (e)->back_edge_prob |
2618 | = ((e->probability * BLOCK_INFO (bb)->frequency) | |
2619 | / REG_BR_PROB_BASE); */ | |
b8698a0f | 2620 | |
fd27ffab | 2621 | sreal tmp = e->probability; |
618b7f29 TS |
2622 | tmp *= BLOCK_INFO (bb)->frequency; |
2623 | EDGE_INFO (e)->back_edge_prob = tmp * real_inv_br_prob_base; | |
9ff3d2de | 2624 | } |
861f9cd0 | 2625 | |
57cb6d52 | 2626 | /* Propagate to successor blocks. */ |
628f6a4e | 2627 | FOR_EACH_EDGE (e, ei, bb->succs) |
247a370b | 2628 | if (!(e->flags & EDGE_DFS_BACK) |
754d9299 | 2629 | && BLOCK_INFO (e->dest)->npredecessors) |
861f9cd0 | 2630 | { |
754d9299 JM |
2631 | BLOCK_INFO (e->dest)->npredecessors--; |
2632 | if (!BLOCK_INFO (e->dest)->npredecessors) | |
247a370b JH |
2633 | { |
2634 | if (!nextbb) | |
2635 | nextbb = e->dest; | |
2636 | else | |
2637 | BLOCK_INFO (last)->next = e->dest; | |
b8698a0f | 2638 | |
247a370b JH |
2639 | last = e->dest; |
2640 | } | |
628f6a4e | 2641 | } |
861f9cd0 JH |
2642 | } |
2643 | } | |
2644 | ||
67fa7880 | 2645 | /* Estimate frequencies in loops at same nest level. */ |
bfdade77 | 2646 | |
861f9cd0 | 2647 | static void |
598ec7bd | 2648 | estimate_loops_at_level (struct loop *first_loop) |
861f9cd0 | 2649 | { |
2ecfd709 | 2650 | struct loop *loop; |
861f9cd0 JH |
2651 | |
2652 | for (loop = first_loop; loop; loop = loop->next) | |
2653 | { | |
861f9cd0 | 2654 | edge e; |
2ecfd709 | 2655 | basic_block *bbs; |
3d436d2a | 2656 | unsigned i; |
598ec7bd | 2657 | bitmap tovisit = BITMAP_ALLOC (NULL); |
861f9cd0 | 2658 | |
598ec7bd | 2659 | estimate_loops_at_level (loop->inner); |
79a490a9 | 2660 | |
598ec7bd ZD |
2661 | /* Find current loop back edge and mark it. */ |
2662 | e = loop_latch_edge (loop); | |
2663 | EDGE_INFO (e)->back_edge = 1; | |
2ecfd709 ZD |
2664 | |
2665 | bbs = get_loop_body (loop); | |
2666 | for (i = 0; i < loop->num_nodes; i++) | |
8a998e0c | 2667 | bitmap_set_bit (tovisit, bbs[i]->index); |
2ecfd709 | 2668 | free (bbs); |
598ec7bd ZD |
2669 | propagate_freq (loop->header, tovisit); |
2670 | BITMAP_FREE (tovisit); | |
861f9cd0 JH |
2671 | } |
2672 | } | |
2673 | ||
2f8e468b | 2674 | /* Propagates frequencies through structure of loops. */ |
598ec7bd ZD |
2675 | |
2676 | static void | |
d73be268 | 2677 | estimate_loops (void) |
598ec7bd ZD |
2678 | { |
2679 | bitmap tovisit = BITMAP_ALLOC (NULL); | |
2680 | basic_block bb; | |
2681 | ||
2682 | /* Start by estimating the frequencies in the loops. */ | |
0fc822d0 | 2683 | if (number_of_loops (cfun) > 1) |
d73be268 | 2684 | estimate_loops_at_level (current_loops->tree_root->inner); |
598ec7bd ZD |
2685 | |
2686 | /* Now propagate the frequencies through all the blocks. */ | |
04a90bec | 2687 | FOR_ALL_BB_FN (bb, cfun) |
598ec7bd ZD |
2688 | { |
2689 | bitmap_set_bit (tovisit, bb->index); | |
2690 | } | |
fefa31b5 | 2691 | propagate_freq (ENTRY_BLOCK_PTR_FOR_FN (cfun), tovisit); |
598ec7bd ZD |
2692 | BITMAP_FREE (tovisit); |
2693 | } | |
2694 | ||
eb4b92c1 | 2695 | /* Drop the profile for NODE to guessed, and update its frequency based on |
4c7d0777 | 2696 | whether it is expected to be hot given the CALL_COUNT. */ |
eb4b92c1 TJ |
2697 | |
2698 | static void | |
4c7d0777 | 2699 | drop_profile (struct cgraph_node *node, gcov_type call_count) |
eb4b92c1 TJ |
2700 | { |
2701 | struct function *fn = DECL_STRUCT_FUNCTION (node->decl); | |
4c7d0777 TJ |
2702 | /* In the case where this was called by another function with a |
2703 | dropped profile, call_count will be 0. Since there are no | |
2704 | non-zero call counts to this function, we don't know for sure | |
2705 | whether it is hot, and therefore it will be marked normal below. */ | |
2706 | bool hot = maybe_hot_count_p (NULL, call_count); | |
eb4b92c1 TJ |
2707 | |
2708 | if (dump_file) | |
2709 | fprintf (dump_file, | |
2710 | "Dropping 0 profile for %s/%i. %s based on calls.\n", | |
fec39fa6 | 2711 | node->name (), node->order, |
eb4b92c1 TJ |
2712 | hot ? "Function is hot" : "Function is normal"); |
2713 | /* We only expect to miss profiles for functions that are reached | |
2714 | via non-zero call edges in cases where the function may have | |
2715 | been linked from another module or library (COMDATs and extern | |
4c7d0777 TJ |
2716 | templates). See the comments below for handle_missing_profiles. |
2717 | Also, only warn in cases where the missing counts exceed the | |
2718 | number of training runs. In certain cases with an execv followed | |
2719 | by a no-return call the profile for the no-return call is not | |
2720 | dumped and there can be a mismatch. */ | |
2721 | if (!DECL_COMDAT (node->decl) && !DECL_EXTERNAL (node->decl) | |
2722 | && call_count > profile_info->runs) | |
eb4b92c1 TJ |
2723 | { |
2724 | if (flag_profile_correction) | |
2725 | { | |
2726 | if (dump_file) | |
2727 | fprintf (dump_file, | |
2728 | "Missing counts for called function %s/%i\n", | |
fec39fa6 | 2729 | node->name (), node->order); |
eb4b92c1 TJ |
2730 | } |
2731 | else | |
4c7d0777 | 2732 | warning (0, "Missing counts for called function %s/%i", |
fec39fa6 | 2733 | node->name (), node->order); |
eb4b92c1 TJ |
2734 | } |
2735 | ||
ea19eb9f | 2736 | profile_status_for_fn (fn) |
eb4b92c1 TJ |
2737 | = (flag_guess_branch_prob ? PROFILE_GUESSED : PROFILE_ABSENT); |
2738 | node->frequency | |
2739 | = hot ? NODE_FREQUENCY_HOT : NODE_FREQUENCY_NORMAL; | |
2740 | } | |
2741 | ||
2742 | /* In the case of COMDAT routines, multiple object files will contain the same | |
2743 | function and the linker will select one for the binary. In that case | |
2744 | all the other copies from the profile instrument binary will be missing | |
2745 | profile counts. Look for cases where this happened, due to non-zero | |
2746 | call counts going to 0-count functions, and drop the profile to guessed | |
2747 | so that we can use the estimated probabilities and avoid optimizing only | |
2748 | for size. | |
2749 | ||
2750 | The other case where the profile may be missing is when the routine | |
2751 | is not going to be emitted to the object file, e.g. for "extern template" | |
2752 | class methods. Those will be marked DECL_EXTERNAL. Emit a warning in | |
2753 | all other cases of non-zero calls to 0-count functions. */ | |
2754 | ||
2755 | void | |
2756 | handle_missing_profiles (void) | |
2757 | { | |
2758 | struct cgraph_node *node; | |
2759 | int unlikely_count_fraction = PARAM_VALUE (UNLIKELY_BB_COUNT_FRACTION); | |
2760 | vec<struct cgraph_node *> worklist; | |
2761 | worklist.create (64); | |
2762 | ||
2763 | /* See if 0 count function has non-0 count callers. In this case we | |
2764 | lost some profile. Drop its function profile to PROFILE_GUESSED. */ | |
2765 | FOR_EACH_DEFINED_FUNCTION (node) | |
2766 | { | |
2767 | struct cgraph_edge *e; | |
2768 | gcov_type call_count = 0; | |
9cec31f4 | 2769 | gcov_type max_tp_first_run = 0; |
eb4b92c1 TJ |
2770 | struct function *fn = DECL_STRUCT_FUNCTION (node->decl); |
2771 | ||
2772 | if (node->count) | |
2773 | continue; | |
2774 | for (e = node->callers; e; e = e->next_caller) | |
9cec31f4 | 2775 | { |
eb4b92c1 | 2776 | call_count += e->count; |
9cec31f4 ML |
2777 | |
2778 | if (e->caller->tp_first_run > max_tp_first_run) | |
2779 | max_tp_first_run = e->caller->tp_first_run; | |
2780 | } | |
2781 | ||
2782 | /* If time profile is missing, let assign the maximum that comes from | |
2783 | caller functions. */ | |
2784 | if (!node->tp_first_run && max_tp_first_run) | |
2785 | node->tp_first_run = max_tp_first_run + 1; | |
2786 | ||
eb4b92c1 TJ |
2787 | if (call_count |
2788 | && fn && fn->cfg | |
2789 | && (call_count * unlikely_count_fraction >= profile_info->runs)) | |
2790 | { | |
4c7d0777 | 2791 | drop_profile (node, call_count); |
eb4b92c1 TJ |
2792 | worklist.safe_push (node); |
2793 | } | |
2794 | } | |
2795 | ||
2796 | /* Propagate the profile dropping to other 0-count COMDATs that are | |
2797 | potentially called by COMDATs we already dropped the profile on. */ | |
2798 | while (worklist.length () > 0) | |
2799 | { | |
2800 | struct cgraph_edge *e; | |
2801 | ||
2802 | node = worklist.pop (); | |
2803 | for (e = node->callees; e; e = e->next_caller) | |
2804 | { | |
2805 | struct cgraph_node *callee = e->callee; | |
2806 | struct function *fn = DECL_STRUCT_FUNCTION (callee->decl); | |
2807 | ||
2808 | if (callee->count > 0) | |
2809 | continue; | |
2810 | if (DECL_COMDAT (callee->decl) && fn && fn->cfg | |
ea19eb9f | 2811 | && profile_status_for_fn (fn) == PROFILE_READ) |
eb4b92c1 | 2812 | { |
4c7d0777 | 2813 | drop_profile (node, 0); |
eb4b92c1 TJ |
2814 | worklist.safe_push (callee); |
2815 | } | |
2816 | } | |
2817 | } | |
2818 | worklist.release (); | |
2819 | } | |
2820 | ||
02307675 R |
2821 | /* Convert counts measured by profile driven feedback to frequencies. |
2822 | Return nonzero iff there was any nonzero execution count. */ | |
bfdade77 | 2823 | |
bbd236a1 | 2824 | int |
79a490a9 | 2825 | counts_to_freqs (void) |
861f9cd0 | 2826 | { |
02307675 | 2827 | gcov_type count_max, true_count_max = 0; |
e0082a72 | 2828 | basic_block bb; |
0b17ab2f | 2829 | |
eb4b92c1 TJ |
2830 | /* Don't overwrite the estimated frequencies when the profile for |
2831 | the function is missing. We may drop this function PROFILE_GUESSED | |
2832 | later in drop_profile (). */ | |
be3c16c4 | 2833 | if (!flag_auto_profile && !ENTRY_BLOCK_PTR_FOR_FN (cfun)->count) |
eb4b92c1 TJ |
2834 | return 0; |
2835 | ||
fefa31b5 | 2836 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
02307675 | 2837 | true_count_max = MAX (bb->count, true_count_max); |
861f9cd0 | 2838 | |
02307675 | 2839 | count_max = MAX (true_count_max, 1); |
fefa31b5 | 2840 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
e0082a72 | 2841 | bb->frequency = (bb->count * BB_FREQ_MAX + count_max / 2) / count_max; |
6bad2617 | 2842 | |
02307675 | 2843 | return true_count_max; |
861f9cd0 JH |
2844 | } |
2845 | ||
bfdade77 RK |
2846 | /* Return true if function is likely to be expensive, so there is no point to |
2847 | optimize performance of prologue, epilogue or do inlining at the expense | |
d55d8fc7 | 2848 | of code size growth. THRESHOLD is the limit of number of instructions |
bfdade77 RK |
2849 | function can execute at average to be still considered not expensive. */ |
2850 | ||
6ab16dd9 | 2851 | bool |
79a490a9 | 2852 | expensive_function_p (int threshold) |
6ab16dd9 JH |
2853 | { |
2854 | unsigned int sum = 0; | |
e0082a72 | 2855 | basic_block bb; |
5197bd50 | 2856 | unsigned int limit; |
6ab16dd9 JH |
2857 | |
2858 | /* We can not compute accurately for large thresholds due to scaled | |
2859 | frequencies. */ | |
e16acfcd | 2860 | gcc_assert (threshold <= BB_FREQ_MAX); |
6ab16dd9 | 2861 | |
eaec9b3d | 2862 | /* Frequencies are out of range. This either means that function contains |
6ab16dd9 JH |
2863 | internal loop executing more than BB_FREQ_MAX times or profile feedback |
2864 | is available and function has not been executed at all. */ | |
fefa31b5 | 2865 | if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency == 0) |
6ab16dd9 | 2866 | return true; |
6a4d6760 | 2867 | |
6ab16dd9 | 2868 | /* Maximally BB_FREQ_MAX^2 so overflow won't happen. */ |
fefa31b5 | 2869 | limit = ENTRY_BLOCK_PTR_FOR_FN (cfun)->frequency * threshold; |
11cd3bed | 2870 | FOR_EACH_BB_FN (bb, cfun) |
6ab16dd9 | 2871 | { |
9f215bf5 | 2872 | rtx_insn *insn; |
6ab16dd9 | 2873 | |
39718607 | 2874 | FOR_BB_INSNS (bb, insn) |
bfdade77 RK |
2875 | if (active_insn_p (insn)) |
2876 | { | |
2877 | sum += bb->frequency; | |
2878 | if (sum > limit) | |
2879 | return true; | |
6ab16dd9 JH |
2880 | } |
2881 | } | |
bfdade77 | 2882 | |
6ab16dd9 JH |
2883 | return false; |
2884 | } | |
2885 | ||
67fa7880 TJ |
2886 | /* Estimate and propagate basic block frequencies using the given branch |
2887 | probabilities. If FORCE is true, the frequencies are used to estimate | |
2888 | the counts even when there are already non-zero profile counts. */ | |
bfdade77 | 2889 | |
45a80bb9 | 2890 | void |
67fa7880 | 2891 | estimate_bb_frequencies (bool force) |
861f9cd0 | 2892 | { |
e0082a72 | 2893 | basic_block bb; |
ac5e69da | 2894 | sreal freq_max; |
8aa18a7d | 2895 | |
0a6a6ac9 | 2896 | if (force || profile_status_for_fn (cfun) != PROFILE_READ || !counts_to_freqs ()) |
194734e9 | 2897 | { |
c4f6b78e RE |
2898 | static int real_values_initialized = 0; |
2899 | ||
2900 | if (!real_values_initialized) | |
2901 | { | |
85bb9c2a | 2902 | real_values_initialized = 1; |
fd27ffab ML |
2903 | real_br_prob_base = REG_BR_PROB_BASE; |
2904 | real_bb_freq_max = BB_FREQ_MAX; | |
618b7f29 | 2905 | real_one_half = sreal (1, -1); |
fd27ffab ML |
2906 | real_inv_br_prob_base = sreal (1) / real_br_prob_base; |
2907 | real_almost_one = sreal (1) - real_inv_br_prob_base; | |
c4f6b78e | 2908 | } |
861f9cd0 | 2909 | |
194734e9 | 2910 | mark_dfs_back_edges (); |
194734e9 | 2911 | |
fefa31b5 DM |
2912 | single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))->probability = |
2913 | REG_BR_PROB_BASE; | |
194734e9 JH |
2914 | |
2915 | /* Set up block info for each basic block. */ | |
11478306 JH |
2916 | alloc_aux_for_blocks (sizeof (block_info)); |
2917 | alloc_aux_for_edges (sizeof (edge_prob_info)); | |
fefa31b5 | 2918 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
861f9cd0 | 2919 | { |
861f9cd0 | 2920 | edge e; |
628f6a4e | 2921 | edge_iterator ei; |
194734e9 | 2922 | |
628f6a4e | 2923 | FOR_EACH_EDGE (e, ei, bb->succs) |
861f9cd0 | 2924 | { |
fd27ffab | 2925 | EDGE_INFO (e)->back_edge_prob = e->probability; |
618b7f29 | 2926 | EDGE_INFO (e)->back_edge_prob *= real_inv_br_prob_base; |
861f9cd0 | 2927 | } |
861f9cd0 | 2928 | } |
bfdade77 | 2929 | |
67fa7880 TJ |
2930 | /* First compute frequencies locally for each loop from innermost |
2931 | to outermost to examine frequencies for back edges. */ | |
d73be268 | 2932 | estimate_loops (); |
861f9cd0 | 2933 | |
fd27ffab | 2934 | freq_max = 0; |
11cd3bed | 2935 | FOR_EACH_BB_FN (bb, cfun) |
618b7f29 TS |
2936 | if (freq_max < BLOCK_INFO (bb)->frequency) |
2937 | freq_max = BLOCK_INFO (bb)->frequency; | |
fbe3b30b | 2938 | |
618b7f29 | 2939 | freq_max = real_bb_freq_max / freq_max; |
fefa31b5 | 2940 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
8aa18a7d | 2941 | { |
618b7f29 TS |
2942 | sreal tmp = BLOCK_INFO (bb)->frequency * freq_max + real_one_half; |
2943 | bb->frequency = tmp.to_int (); | |
194734e9 | 2944 | } |
bfdade77 | 2945 | |
194734e9 JH |
2946 | free_aux_for_blocks (); |
2947 | free_aux_for_edges (); | |
2948 | } | |
2949 | compute_function_frequency (); | |
194734e9 | 2950 | } |
861f9cd0 | 2951 | |
194734e9 | 2952 | /* Decide whether function is hot, cold or unlikely executed. */ |
965b98d0 | 2953 | void |
79a490a9 | 2954 | compute_function_frequency (void) |
194734e9 | 2955 | { |
e0082a72 | 2956 | basic_block bb; |
d52f5295 | 2957 | struct cgraph_node *node = cgraph_node::get (current_function_decl); |
daf5c770 | 2958 | |
844db5d0 JH |
2959 | if (DECL_STATIC_CONSTRUCTOR (current_function_decl) |
2960 | || MAIN_NAME_P (DECL_NAME (current_function_decl))) | |
2961 | node->only_called_at_startup = true; | |
2962 | if (DECL_STATIC_DESTRUCTOR (current_function_decl)) | |
2963 | node->only_called_at_exit = true; | |
e0082a72 | 2964 | |
0a6a6ac9 | 2965 | if (profile_status_for_fn (cfun) != PROFILE_READ) |
52bf96d2 | 2966 | { |
5fefcf92 | 2967 | int flags = flags_from_decl_or_type (current_function_decl); |
52bf96d2 JH |
2968 | if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl)) |
2969 | != NULL) | |
5fefcf92 | 2970 | node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; |
52bf96d2 JH |
2971 | else if (lookup_attribute ("hot", DECL_ATTRIBUTES (current_function_decl)) |
2972 | != NULL) | |
5fefcf92 JH |
2973 | node->frequency = NODE_FREQUENCY_HOT; |
2974 | else if (flags & ECF_NORETURN) | |
2975 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
2976 | else if (MAIN_NAME_P (DECL_NAME (current_function_decl))) | |
2977 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
2978 | else if (DECL_STATIC_CONSTRUCTOR (current_function_decl) | |
2979 | || DECL_STATIC_DESTRUCTOR (current_function_decl)) | |
2980 | node->frequency = NODE_FREQUENCY_EXECUTED_ONCE; | |
52bf96d2 JH |
2981 | return; |
2982 | } | |
daf5c770 JH |
2983 | |
2984 | /* Only first time try to drop function into unlikely executed. | |
2985 | After inlining the roundoff errors may confuse us. | |
2986 | Ipa-profile pass will drop functions only called from unlikely | |
2987 | functions to unlikely and that is most of what we care about. */ | |
2988 | if (!cfun->after_inlining) | |
2989 | node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; | |
11cd3bed | 2990 | FOR_EACH_BB_FN (bb, cfun) |
861f9cd0 | 2991 | { |
2eb712b4 | 2992 | if (maybe_hot_bb_p (cfun, bb)) |
194734e9 | 2993 | { |
5fefcf92 | 2994 | node->frequency = NODE_FREQUENCY_HOT; |
194734e9 JH |
2995 | return; |
2996 | } | |
2eb712b4 | 2997 | if (!probably_never_executed_bb_p (cfun, bb)) |
5fefcf92 | 2998 | node->frequency = NODE_FREQUENCY_NORMAL; |
861f9cd0 | 2999 | } |
194734e9 | 3000 | } |
861f9cd0 | 3001 | |
2e28e797 JH |
3002 | /* Build PREDICT_EXPR. */ |
3003 | tree | |
3004 | build_predict_expr (enum br_predictor predictor, enum prediction taken) | |
3005 | { | |
9d7e5c4d | 3006 | tree t = build1 (PREDICT_EXPR, void_type_node, |
9f616812 | 3007 | build_int_cst (integer_type_node, predictor)); |
bbbbb16a | 3008 | SET_PREDICT_EXPR_OUTCOME (t, taken); |
2e28e797 JH |
3009 | return t; |
3010 | } | |
3011 | ||
3012 | const char * | |
3013 | predictor_name (enum br_predictor predictor) | |
3014 | { | |
3015 | return predictor_info[predictor].name; | |
3016 | } | |
3017 | ||
be55bfe6 TS |
3018 | /* Predict branch probabilities and estimate profile of the tree CFG. */ |
3019 | ||
27a4cd48 DM |
3020 | namespace { |
3021 | ||
3022 | const pass_data pass_data_profile = | |
3023 | { | |
3024 | GIMPLE_PASS, /* type */ | |
3025 | "profile_estimate", /* name */ | |
3026 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
3027 | TV_BRANCH_PROB, /* tv_id */ |
3028 | PROP_cfg, /* properties_required */ | |
3029 | 0, /* properties_provided */ | |
3030 | 0, /* properties_destroyed */ | |
3031 | 0, /* todo_flags_start */ | |
3bea341f | 3032 | 0, /* todo_flags_finish */ |
6de9cd9a | 3033 | }; |
7299cb99 | 3034 | |
27a4cd48 DM |
3035 | class pass_profile : public gimple_opt_pass |
3036 | { | |
3037 | public: | |
c3284718 RS |
3038 | pass_profile (gcc::context *ctxt) |
3039 | : gimple_opt_pass (pass_data_profile, ctxt) | |
27a4cd48 DM |
3040 | {} |
3041 | ||
3042 | /* opt_pass methods: */ | |
1a3d085c | 3043 | virtual bool gate (function *) { return flag_guess_branch_prob; } |
be55bfe6 | 3044 | virtual unsigned int execute (function *); |
27a4cd48 DM |
3045 | |
3046 | }; // class pass_profile | |
3047 | ||
be55bfe6 TS |
3048 | unsigned int |
3049 | pass_profile::execute (function *fun) | |
3050 | { | |
3051 | unsigned nb_loops; | |
3052 | ||
10881cff JH |
3053 | if (profile_status_for_fn (cfun) == PROFILE_GUESSED) |
3054 | return 0; | |
3055 | ||
be55bfe6 TS |
3056 | loop_optimizer_init (LOOPS_NORMAL); |
3057 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3058 | flow_loops_dump (dump_file, NULL, 0); | |
3059 | ||
3060 | mark_irreducible_loops (); | |
3061 | ||
3062 | nb_loops = number_of_loops (fun); | |
3063 | if (nb_loops > 1) | |
3064 | scev_initialize (); | |
3065 | ||
3066 | tree_estimate_probability (); | |
3067 | ||
3068 | if (nb_loops > 1) | |
3069 | scev_finalize (); | |
3070 | ||
3071 | loop_optimizer_finalize (); | |
3072 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3073 | gimple_dump_cfg (dump_file, dump_flags); | |
3074 | if (profile_status_for_fn (fun) == PROFILE_ABSENT) | |
3075 | profile_status_for_fn (fun) = PROFILE_GUESSED; | |
3076 | return 0; | |
3077 | } | |
3078 | ||
27a4cd48 DM |
3079 | } // anon namespace |
3080 | ||
3081 | gimple_opt_pass * | |
3082 | make_pass_profile (gcc::context *ctxt) | |
3083 | { | |
3084 | return new pass_profile (ctxt); | |
3085 | } | |
3086 | ||
3087 | namespace { | |
3088 | ||
3089 | const pass_data pass_data_strip_predict_hints = | |
3090 | { | |
3091 | GIMPLE_PASS, /* type */ | |
3092 | "*strip_predict_hints", /* name */ | |
3093 | OPTGROUP_NONE, /* optinfo_flags */ | |
27a4cd48 DM |
3094 | TV_BRANCH_PROB, /* tv_id */ |
3095 | PROP_cfg, /* properties_required */ | |
3096 | 0, /* properties_provided */ | |
3097 | 0, /* properties_destroyed */ | |
3098 | 0, /* todo_flags_start */ | |
3bea341f | 3099 | 0, /* todo_flags_finish */ |
7299cb99 | 3100 | }; |
b35366ce | 3101 | |
27a4cd48 DM |
3102 | class pass_strip_predict_hints : public gimple_opt_pass |
3103 | { | |
3104 | public: | |
c3284718 RS |
3105 | pass_strip_predict_hints (gcc::context *ctxt) |
3106 | : gimple_opt_pass (pass_data_strip_predict_hints, ctxt) | |
27a4cd48 DM |
3107 | {} |
3108 | ||
3109 | /* opt_pass methods: */ | |
65d3284b | 3110 | opt_pass * clone () { return new pass_strip_predict_hints (m_ctxt); } |
be55bfe6 | 3111 | virtual unsigned int execute (function *); |
27a4cd48 DM |
3112 | |
3113 | }; // class pass_strip_predict_hints | |
3114 | ||
be55bfe6 TS |
3115 | /* Get rid of all builtin_expect calls and GIMPLE_PREDICT statements |
3116 | we no longer need. */ | |
3117 | unsigned int | |
3118 | pass_strip_predict_hints::execute (function *fun) | |
3119 | { | |
3120 | basic_block bb; | |
3121 | gimple ass_stmt; | |
3122 | tree var; | |
3123 | ||
3124 | FOR_EACH_BB_FN (bb, fun) | |
3125 | { | |
3126 | gimple_stmt_iterator bi; | |
3127 | for (bi = gsi_start_bb (bb); !gsi_end_p (bi);) | |
3128 | { | |
3129 | gimple stmt = gsi_stmt (bi); | |
3130 | ||
3131 | if (gimple_code (stmt) == GIMPLE_PREDICT) | |
3132 | { | |
3133 | gsi_remove (&bi, true); | |
3134 | continue; | |
3135 | } | |
3136 | else if (is_gimple_call (stmt)) | |
3137 | { | |
3138 | tree fndecl = gimple_call_fndecl (stmt); | |
3139 | ||
3140 | if ((fndecl | |
3141 | && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL | |
3142 | && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_EXPECT | |
3143 | && gimple_call_num_args (stmt) == 2) | |
3144 | || (gimple_call_internal_p (stmt) | |
3145 | && gimple_call_internal_fn (stmt) == IFN_BUILTIN_EXPECT)) | |
3146 | { | |
3147 | var = gimple_call_lhs (stmt); | |
3148 | if (var) | |
3149 | { | |
3150 | ass_stmt | |
3151 | = gimple_build_assign (var, gimple_call_arg (stmt, 0)); | |
3152 | gsi_replace (&bi, ass_stmt, true); | |
3153 | } | |
3154 | else | |
3155 | { | |
3156 | gsi_remove (&bi, true); | |
3157 | continue; | |
3158 | } | |
3159 | } | |
3160 | } | |
3161 | gsi_next (&bi); | |
3162 | } | |
3163 | } | |
3164 | return 0; | |
3165 | } | |
3166 | ||
27a4cd48 DM |
3167 | } // anon namespace |
3168 | ||
3169 | gimple_opt_pass * | |
3170 | make_pass_strip_predict_hints (gcc::context *ctxt) | |
3171 | { | |
3172 | return new pass_strip_predict_hints (ctxt); | |
3173 | } | |
3174 | ||
b35366ce JH |
3175 | /* Rebuild function frequencies. Passes are in general expected to |
3176 | maintain profile by hand, however in some cases this is not possible: | |
3177 | for example when inlining several functions with loops freuqencies might run | |
3178 | out of scale and thus needs to be recomputed. */ | |
3179 | ||
3180 | void | |
3181 | rebuild_frequencies (void) | |
3182 | { | |
a222c01a | 3183 | timevar_push (TV_REBUILD_FREQUENCIES); |
67fa7880 TJ |
3184 | |
3185 | /* When the max bb count in the function is small, there is a higher | |
3186 | chance that there were truncation errors in the integer scaling | |
3187 | of counts by inlining and other optimizations. This could lead | |
3188 | to incorrect classification of code as being cold when it isn't. | |
3189 | In that case, force the estimation of bb counts/frequencies from the | |
3190 | branch probabilities, rather than computing frequencies from counts, | |
3191 | which may also lead to frequencies incorrectly reduced to 0. There | |
3192 | is less precision in the probabilities, so we only do this for small | |
3193 | max counts. */ | |
3194 | gcov_type count_max = 0; | |
3195 | basic_block bb; | |
fefa31b5 | 3196 | FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun), NULL, next_bb) |
67fa7880 TJ |
3197 | count_max = MAX (bb->count, count_max); |
3198 | ||
0a6a6ac9 | 3199 | if (profile_status_for_fn (cfun) == PROFILE_GUESSED |
be3c16c4 DC |
3200 | || (!flag_auto_profile && profile_status_for_fn (cfun) == PROFILE_READ |
3201 | && count_max < REG_BR_PROB_BASE/10)) | |
b35366ce JH |
3202 | { |
3203 | loop_optimizer_init (0); | |
3204 | add_noreturn_fake_exit_edges (); | |
3205 | mark_irreducible_loops (); | |
3206 | connect_infinite_loops_to_exit (); | |
67fa7880 | 3207 | estimate_bb_frequencies (true); |
b35366ce JH |
3208 | remove_fake_exit_edges (); |
3209 | loop_optimizer_finalize (); | |
3210 | } | |
0a6a6ac9 | 3211 | else if (profile_status_for_fn (cfun) == PROFILE_READ) |
b35366ce JH |
3212 | counts_to_freqs (); |
3213 | else | |
3214 | gcc_unreachable (); | |
a222c01a | 3215 | timevar_pop (TV_REBUILD_FREQUENCIES); |
b35366ce | 3216 | } |