Mercurial > hg > CbC > CbC_gcc
annotate gcc/predict.def @ 131:84e7813d76e9
gcc-8.2
author | mir3636 |
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date | Thu, 25 Oct 2018 07:37:49 +0900 |
parents | 04ced10e8804 |
children | 1830386684a0 |
rev | line source |
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0 | 1 /* Definitions for the branch prediction routines in the GNU compiler. |
131 | 2 Copyright (C) 2001-2018 Free Software Foundation, Inc. |
0 | 3 |
4 This file is part of GCC. | |
5 | |
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 | |
8 Software Foundation; either version 3, or (at your option) any later | |
9 version. | |
10 | |
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. | |
15 | |
16 You should have received a copy of the GNU General Public License | |
17 along with GCC; see the file COPYING3. If not see | |
18 <http://www.gnu.org/licenses/>. */ | |
19 | |
20 /* Before including this file, you should define a macro: | |
21 | |
22 DEF_PREDICTOR (ENUM, NAME, HITRATE) | |
23 | |
24 This macro will be called once for each predictor. The ENUM will | |
131 | 25 be of type `enum br_predictor', and will enumerate all supported |
0 | 26 predictors. The order of DEF_PREDICTOR calls is important, as |
27 in the first match combining heuristics, the predictor appearing | |
28 first in this file will win. | |
29 | |
30 NAME is used in the debugging output to determine predictor type. | |
31 | |
32 HITRATE is the probability that edge predicted by predictor as taken | |
33 will be really taken (so it should be always above | |
34 REG_BR_PROB_BASE / 2). */ | |
55
77e2b8dfacca
update it from 4.4.3 to 4.5.0
ryoma <e075725@ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
35 |
0 | 36 |
37 /* A value used as final outcome of all heuristics. */ | |
38 DEF_PREDICTOR (PRED_COMBINED, "combined", PROB_ALWAYS, 0) | |
39 | |
40 /* An outcome estimated by Dempster-Shaffer theory. */ | |
41 DEF_PREDICTOR (PRED_DS_THEORY, "DS theory", PROB_ALWAYS, 0) | |
42 | |
43 /* A combined heuristics using probability determined by first | |
44 matching heuristics from this list. */ | |
45 DEF_PREDICTOR (PRED_FIRST_MATCH, "first match", PROB_ALWAYS, 0) | |
46 | |
47 /* Heuristic applying when no heuristic below applies. */ | |
48 DEF_PREDICTOR (PRED_NO_PREDICTION, "no prediction", PROB_ALWAYS, 0) | |
49 | |
50 /* Mark unconditional jump as taken. */ | |
51 DEF_PREDICTOR (PRED_UNCONDITIONAL, "unconditional jump", PROB_ALWAYS, | |
52 PRED_FLAG_FIRST_MATCH) | |
53 | |
131 | 54 /* Return value of malloc function is almost always non-null. */ |
55 DEF_PREDICTOR (PRED_MALLOC_NONNULL, "malloc returned non-NULL", \ | |
56 PROB_VERY_LIKELY, PRED_FLAG_FIRST_MATCH) | |
57 | |
0 | 58 /* Use number of loop iterations determined by # of iterations |
59 analysis to set probability. We don't want to use Dempster-Shaffer | |
60 theory here, as the predictions is exact. */ | |
131 | 61 DEF_PREDICTOR (PRED_LOOP_ITERATIONS, "loop iterations", PROB_UNINITIALIZED, |
0 | 62 PRED_FLAG_FIRST_MATCH) |
63 | |
111 | 64 /* Assume that any given atomic operation has low contention, |
65 and thus the compare-and-swap operation succeeds. */ | |
66 DEF_PREDICTOR (PRED_COMPARE_AND_SWAP, "compare and swap", PROB_VERY_LIKELY, | |
67 PRED_FLAG_FIRST_MATCH) | |
68 | |
69 /* Hints dropped by user via __builtin_expect feature. Note: the | |
70 probability of PROB_VERY_LIKELY is now overwritten by param | |
71 builtin_expect_probability with a default value of HITRATE(90). | |
72 Refer to param.def for details. */ | |
0 | 73 DEF_PREDICTOR (PRED_BUILTIN_EXPECT, "__builtin_expect", PROB_VERY_LIKELY, |
74 PRED_FLAG_FIRST_MATCH) | |
75 | |
131 | 76 /* Hints provided by user via __builtin_expect_with_probability. */ |
77 DEF_PREDICTOR (PRED_BUILTIN_EXPECT_WITH_PROBABILITY, | |
78 "__builtin_expect_with_probability", PROB_UNINITIALIZED, | |
79 PRED_FLAG_FIRST_MATCH) | |
80 | |
0 | 81 /* Use number of loop iterations guessed by the contents of the loop. */ |
82 DEF_PREDICTOR (PRED_LOOP_ITERATIONS_GUESSED, "guessed loop iterations", | |
131 | 83 PROB_UNINITIALIZED, PRED_FLAG_FIRST_MATCH) |
0 | 84 |
111 | 85 /* Use number of loop iterations guessed by the contents of the loop. */ |
86 DEF_PREDICTOR (PRED_LOOP_ITERATIONS_MAX, "guessed loop iterations", | |
131 | 87 PROB_UNINITIALIZED, PRED_FLAG_FIRST_MATCH) |
111 | 88 |
0 | 89 /* Branch containing goto is probably not taken. */ |
111 | 90 DEF_PREDICTOR (PRED_CONTINUE, "continue", HITRATE (67), 0) |
0 | 91 |
92 /* Branch to basic block containing call marked by noreturn attribute. */ | |
93 DEF_PREDICTOR (PRED_NORETURN, "noreturn call", PROB_VERY_LIKELY, | |
94 PRED_FLAG_FIRST_MATCH) | |
95 | |
96 /* Branch to basic block containing call marked by cold function attribute. */ | |
97 DEF_PREDICTOR (PRED_COLD_FUNCTION, "cold function call", PROB_VERY_LIKELY, | |
98 PRED_FLAG_FIRST_MATCH) | |
99 | |
111 | 100 /* Edge causing loop to terminate is probably not taken. */ |
131 | 101 DEF_PREDICTOR (PRED_LOOP_EXIT, "loop exit", HITRATE (89), |
0 | 102 PRED_FLAG_FIRST_MATCH) |
103 | |
111 | 104 /* Same as LOOP_EXIT but for loops containing recursive call. */ |
105 DEF_PREDICTOR (PRED_LOOP_EXIT_WITH_RECURSION, "loop exit with recursion", | |
131 | 106 HITRATE (78), PRED_FLAG_FIRST_MATCH) |
111 | 107 |
108 /* Edge causing loop to terminate by computing value used by later | |
109 conditional. */ | |
131 | 110 DEF_PREDICTOR (PRED_LOOP_EXTRA_EXIT, "extra loop exit", HITRATE (67), |
0 | 111 PRED_FLAG_FIRST_MATCH) |
112 | |
113 /* Pointers are usually not NULL. */ | |
111 | 114 DEF_PREDICTOR (PRED_POINTER, "pointer", HITRATE (70), 0) |
115 DEF_PREDICTOR (PRED_TREE_POINTER, "pointer (on trees)", HITRATE (70), 0) | |
0 | 116 |
117 /* NE is probable, EQ not etc... */ | |
131 | 118 DEF_PREDICTOR (PRED_OPCODE_POSITIVE, "opcode values positive", HITRATE (59), 0) |
111 | 119 DEF_PREDICTOR (PRED_OPCODE_NONEQUAL, "opcode values nonequal", HITRATE (66), 0) |
0 | 120 DEF_PREDICTOR (PRED_FPOPCODE, "fp_opcode", HITRATE (90), 0) |
111 | 121 DEF_PREDICTOR (PRED_TREE_OPCODE_POSITIVE, "opcode values positive (on trees)", |
131 | 122 HITRATE (59), 0) |
111 | 123 DEF_PREDICTOR (PRED_TREE_OPCODE_NONEQUAL, "opcode values nonequal (on trees)", |
124 HITRATE (66), 0) | |
0 | 125 DEF_PREDICTOR (PRED_TREE_FPOPCODE, "fp_opcode (on trees)", HITRATE (90), 0) |
126 | |
127 /* Branch guarding call is probably taken. */ | |
111 | 128 DEF_PREDICTOR (PRED_CALL, "call", HITRATE (67), 0) |
129 | |
131 | 130 /* Call predictors are for now ignored, lets leave the predictor |
131 to measure its benefit. */ | |
132 DEF_PREDICTOR (PRED_INDIR_CALL, "indirect call", PROB_EVEN, 0) | |
133 DEF_PREDICTOR (PRED_POLYMORPHIC_CALL, "polymorphic call", PROB_EVEN, 0) | |
134 DEF_PREDICTOR (PRED_RECURSIVE_CALL, "recursive call", PROB_EVEN, 0) | |
0 | 135 |
136 /* Branch causing function to terminate is probably not taken. */ | |
111 | 137 DEF_PREDICTOR (PRED_TREE_EARLY_RETURN, "early return (on trees)", HITRATE (66), |
138 0) | |
0 | 139 |
140 /* Branch containing goto is probably not taken. */ | |
111 | 141 DEF_PREDICTOR (PRED_GOTO, "goto", HITRATE (66), 0) |
0 | 142 |
143 /* Branch ending with return constant is probably not taken. */ | |
131 | 144 DEF_PREDICTOR (PRED_CONST_RETURN, "const return", HITRATE (65), 0) |
0 | 145 |
146 /* Branch ending with return negative constant is probably not taken. */ | |
111 | 147 DEF_PREDICTOR (PRED_NEGATIVE_RETURN, "negative return", HITRATE (98), 0) |
0 | 148 |
149 /* Branch ending with return; is probably not taken */ | |
131 | 150 DEF_PREDICTOR (PRED_NULL_RETURN, "null return", HITRATE (71), 0) |
111 | 151 |
152 /* Branches to compare induction variable to a loop bound is | |
153 extremely likely. */ | |
154 DEF_PREDICTOR (PRED_LOOP_IV_COMPARE_GUESS, "guess loop iv compare", | |
131 | 155 HITRATE (64), 0) |
111 | 156 |
157 /* Use number of loop iterations determined by # of iterations analysis | |
158 to set probability of branches that compares IV to loop bound variable. */ | |
131 | 159 DEF_PREDICTOR (PRED_LOOP_IV_COMPARE, "loop iv compare", PROB_UNINITIALIZED, |
111 | 160 PRED_FLAG_FIRST_MATCH) |
161 | |
162 /* In the following code | |
163 for (loop1) | |
164 if (cond) | |
165 for (loop2) | |
166 body; | |
167 guess that cond is unlikely. */ | |
131 | 168 DEF_PREDICTOR (PRED_LOOP_GUARD, "loop guard", HITRATE (73), 0) |
111 | 169 |
170 /* Same but for loops containing recursion. */ | |
171 DEF_PREDICTOR (PRED_LOOP_GUARD_WITH_RECURSION, "loop guard with recursion", | |
172 HITRATE (85), 0) | |
173 | |
174 /* Branches to hot labels are likely. */ | |
175 DEF_PREDICTOR (PRED_HOT_LABEL, "hot label", HITRATE (85), 0) | |
176 | |
177 /* Branches to cold labels are extremely unlikely. */ | |
178 DEF_PREDICTOR (PRED_COLD_LABEL, "cold label", PROB_VERY_LIKELY, | |
179 PRED_FLAG_FIRST_MATCH) | |
180 | |
181 /* The following predictors are used in Fortran. */ | |
182 | |
183 /* Branch leading to an integer overflow are extremely unlikely. */ | |
184 DEF_PREDICTOR (PRED_FORTRAN_OVERFLOW, "Fortran overflow", PROB_ALWAYS, | |
185 PRED_FLAG_FIRST_MATCH) | |
0 | 186 |
111 | 187 /* Branch leading to a failure status are unlikely. This can occur for out |
188 of memory. This predictor only occurs when the user explicitly asked | |
189 for a return status. By default, the code aborts, | |
190 which is handled via PRED_NORETURN. */ | |
191 DEF_PREDICTOR (PRED_FORTRAN_FAIL_ALLOC, "Fortran fail alloc", | |
192 PROB_VERY_LIKELY, 0) | |
193 | |
194 /* Predictor is used for an allocation of an already allocated memory or | |
195 deallocating an already deallocated allocatable. */ | |
196 DEF_PREDICTOR (PRED_FORTRAN_REALLOC, "Fortran repeated allocation/deallocation", | |
197 PROB_LIKELY, 0) | |
198 | |
199 /* Branch leading to an I/O failure status are unlikely. This predictor is | |
200 used for I/O failures such as for invalid unit numbers. This predictor | |
201 only occurs when the user explicitly asked for a return status. By default, | |
202 the code aborts, which is handled via PRED_NORETURN. */ | |
203 DEF_PREDICTOR (PRED_FORTRAN_FAIL_IO, "Fortran fail IO", HITRATE (85), 0) | |
204 | |
205 /* Branch leading to a run-time warning message which is printed only once | |
206 are unlikely. The print-warning branch itself can be likely or unlikely. */ | |
207 DEF_PREDICTOR (PRED_FORTRAN_WARN_ONCE, "Fortran warn once", HITRATE (75), 0) | |
208 | |
209 /* Branch belonging to a zero-sized array. */ | |
210 DEF_PREDICTOR (PRED_FORTRAN_SIZE_ZERO, "Fortran zero-sized array", \ | |
211 HITRATE (99), 0) | |
212 | |
213 /* Branch belonging to an invalid bound index, in a context where it is | |
214 standard conform and well defined but rather pointless and, hence, rather | |
215 unlikely to occur. */ | |
216 DEF_PREDICTOR (PRED_FORTRAN_INVALID_BOUND, "Fortran invalid bound", \ | |
217 HITRATE (90), 0) | |
218 | |
219 /* Branch belonging to the handling of absent optional arguments. This | |
220 predictor is used when an optional dummy argument, associated with an | |
221 absent argument, is passed on as actual argument to another procedure, | |
222 which in turn has an optional argument. */ | |
223 DEF_PREDICTOR (PRED_FORTRAN_ABSENT_DUMMY, "Fortran absent dummy", \ | |
224 HITRATE (60), 0) | |
225 | |
226 /* Fortran DO statement generates a pre-header guard: | |
227 empty = (step > 0 ? to < from : to > from), which can be predicted | |
228 to be very likely. */ | |
229 DEF_PREDICTOR (PRED_FORTRAN_LOOP_PREHEADER, "Fortran loop preheader", \ | |
230 HITRATE (99), 0) |