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3995f3a2 JH |
1 | /* Profile counter container type. |
2 | Copyright (C) 2017 Free Software Foundation, Inc. | |
3 | Contributed by Jan Hubicka | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9 | Software Foundation; either version 3, or (at your option) any later | |
10 | version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING3. If not see | |
19 | <http://www.gnu.org/licenses/>. */ | |
20 | ||
21 | #ifndef GCC_PROFILE_COUNT_H | |
22 | #define GCC_PROFILE_COUNT_H | |
23 | ||
4e9a497f JH |
24 | /* Quality of the proflie count. Because gengtype does not support enums |
25 | inside of clases, this is in global namespace. */ | |
26 | enum profile_count_quality { | |
27 | /* Profile is based on static branch prediction heuristics. It may or may | |
28 | not reflect the reality. */ | |
29 | count_guessed = 0, | |
30 | /* Profile was determined by autofdo. */ | |
b2c2a7e4 | 31 | count_afdo = 1, |
4e9a497f JH |
32 | /* Profile was originally based on feedback but it was adjusted |
33 | by code duplicating optimization. It may not precisely reflect the | |
34 | particular code path. */ | |
b2c2a7e4 | 35 | count_adjusted = 2, |
4e9a497f JH |
36 | /* Profile was read from profile feedback or determined by accurate static |
37 | method. */ | |
38 | count_read = 3 | |
39 | }; | |
3995f3a2 JH |
40 | |
41 | /* The base value for branch probability notes and edge probabilities. */ | |
42 | #define REG_BR_PROB_BASE 10000 | |
43 | ||
44 | #define RDIV(X,Y) (((X) + (Y) / 2) / (Y)) | |
45 | ||
46 | /* Main data type to hold profile counters in GCC. In most cases profile | |
47 | counts originate from profile feedback. They are 64bit integers | |
48 | representing number of executions during the train run. | |
49 | As the profile is maintained during the compilation, many adjustments are | |
50 | made. Not all transformations can be made precisely, most importantly | |
51 | when code is being duplicated. It also may happen that part of CFG has | |
52 | profile counts known while other do not - for example when LTO optimizing | |
53 | partly profiled program or when profile was lost due to COMDAT merging. | |
54 | ||
b69d9ac6 | 55 | For this reason profile_count tracks more information than |
3995f3a2 JH |
56 | just unsigned integer and it is also ready for profile mismatches. |
57 | The API of this data type represent operations that are natural | |
58 | on profile counts - sum, difference and operation with scales and | |
59 | probabilities. All operations are safe by never getting negative counts | |
60 | and they do end up in uninitialized scale if any of the parameters is | |
61 | uninitialized. | |
62 | ||
63 | All comparsions that are three state and handling of probabilities. Thus | |
64 | a < b is not equal to !(a >= b). | |
65 | ||
66 | The following pre-defined counts are available: | |
67 | ||
68 | profile_count::zero () for code that is known to execute zero times at | |
69 | runtime (this can be detected statically i.e. for paths leading to | |
70 | abort (); | |
71 | profile_count::one () for code that is known to execute once (such as | |
72 | main () function | |
73 | profile_count::uninitialized () for unknown execution count. | |
74 | ||
75 | */ | |
76 | ||
3995f3a2 JH |
77 | class GTY(()) profile_count |
78 | { | |
4e9a497f | 79 | /* Use 62bit to hold basic block counters. Should be at least |
3995f3a2 JH |
80 | 64bit. Although a counter cannot be negative, we use a signed |
81 | type to hold various extra stages. */ | |
82 | ||
4e9a497f JH |
83 | static const int n_bits = 62; |
84 | static const uint64_t max_count = ((uint64_t) 1 << n_bits) - 2; | |
85 | static const uint64_t uninitialized_count = ((uint64_t) 1 << n_bits) - 1; | |
86 | ||
87 | uint64_t m_val : n_bits; | |
88 | enum profile_count_quality m_quality : 2; | |
3995f3a2 JH |
89 | |
90 | /* Assume numbers smaller than this to multiply. This is set to make | |
4e9a497f | 91 | testsuite pass, in future we may implement precise multiplication in higer |
3995f3a2 JH |
92 | rangers. */ |
93 | static const int64_t max_safe_multiplier = 131072; | |
94 | public: | |
95 | ||
96 | /* Used for counters which are expected to be never executed. */ | |
97 | static profile_count zero () | |
98 | { | |
99 | return from_gcov_type (0); | |
100 | } | |
101 | static profile_count one () | |
102 | { | |
103 | return from_gcov_type (1); | |
104 | } | |
105 | /* Value of counters which has not been initialized. Either because | |
106 | initialization did not happen yet or because profile is unknown. */ | |
107 | static profile_count uninitialized () | |
108 | { | |
109 | profile_count c; | |
4e9a497f JH |
110 | c.m_val = uninitialized_count; |
111 | c.m_quality = count_guessed; | |
3995f3a2 JH |
112 | return c; |
113 | } | |
114 | ||
115 | /* The profiling runtime uses gcov_type, which is usually 64bit integer. | |
116 | Conversions back and forth are used to read the coverage and get it | |
117 | into internal representation. */ | |
118 | static profile_count from_gcov_type (gcov_type v) | |
119 | { | |
120 | profile_count ret; | |
4e9a497f | 121 | gcc_checking_assert (v >= 0 && (uint64_t) v <= max_count); |
3995f3a2 | 122 | ret.m_val = v; |
4e9a497f | 123 | ret.m_quality = count_read; |
3995f3a2 JH |
124 | return ret; |
125 | } | |
126 | ||
127 | /* Conversion to gcov_type is lossy. */ | |
128 | gcov_type to_gcov_type () const | |
129 | { | |
130 | gcc_checking_assert (initialized_p ()); | |
131 | return m_val; | |
132 | } | |
133 | ||
134 | /* Return true if value has been initialized. */ | |
135 | bool initialized_p () const | |
136 | { | |
4e9a497f | 137 | return m_val != uninitialized_count; |
3995f3a2 JH |
138 | } |
139 | /* Return true if value can be trusted. */ | |
140 | bool reliable_p () const | |
141 | { | |
142 | return initialized_p (); | |
143 | } | |
144 | ||
145 | /* Basic operations. */ | |
146 | bool operator== (const profile_count &other) const | |
147 | { | |
4e9a497f | 148 | return m_val == other.m_val && m_quality == other.m_quality; |
3995f3a2 JH |
149 | } |
150 | profile_count operator+ (const profile_count &other) const | |
151 | { | |
152 | if (other == profile_count::zero ()) | |
153 | return *this; | |
154 | if (*this == profile_count::zero ()) | |
155 | return other; | |
156 | if (!initialized_p () || !other.initialized_p ()) | |
157 | return profile_count::uninitialized (); | |
158 | ||
159 | profile_count ret; | |
160 | ret.m_val = m_val + other.m_val; | |
4e9a497f | 161 | ret.m_quality = MIN (m_quality, other.m_quality); |
3995f3a2 JH |
162 | return ret; |
163 | } | |
164 | profile_count &operator+= (const profile_count &other) | |
165 | { | |
166 | if (other == profile_count::zero ()) | |
167 | return *this; | |
168 | if (*this == profile_count::zero ()) | |
169 | { | |
170 | *this = other; | |
171 | return *this; | |
172 | } | |
173 | if (!initialized_p () || !other.initialized_p ()) | |
174 | return *this = profile_count::uninitialized (); | |
175 | else | |
4e9a497f JH |
176 | { |
177 | m_val += other.m_val; | |
178 | m_quality = MIN (m_quality, other.m_quality); | |
179 | } | |
3995f3a2 JH |
180 | return *this; |
181 | } | |
182 | profile_count operator- (const profile_count &other) const | |
183 | { | |
184 | if (*this == profile_count::zero () || other == profile_count::zero ()) | |
185 | return *this; | |
186 | if (!initialized_p () || !other.initialized_p ()) | |
187 | return profile_count::uninitialized (); | |
188 | profile_count ret; | |
4e9a497f JH |
189 | ret.m_val = m_val >= other.m_val ? m_val - other.m_val : 0; |
190 | ret.m_quality = MIN (m_quality, other.m_quality); | |
3995f3a2 JH |
191 | return ret; |
192 | } | |
193 | profile_count &operator-= (const profile_count &other) | |
194 | { | |
195 | if (*this == profile_count::zero () || other == profile_count::zero ()) | |
196 | return *this; | |
197 | if (!initialized_p () || !other.initialized_p ()) | |
198 | return *this = profile_count::uninitialized (); | |
199 | else | |
4e9a497f JH |
200 | { |
201 | m_val = m_val >= other.m_val ? m_val - other.m_val: 0; | |
202 | m_quality = MIN (m_quality, other.m_quality); | |
203 | } | |
3995f3a2 JH |
204 | return *this; |
205 | } | |
206 | ||
207 | /* Return false if profile_count is bogus. */ | |
208 | bool verify () const | |
209 | { | |
4e9a497f | 210 | return m_val != uninitialized_count || m_quality == count_guessed; |
3995f3a2 JH |
211 | } |
212 | ||
213 | /* Comparsions are three-state and conservative. False is returned if | |
214 | the inequality can not be decided. */ | |
215 | bool operator< (const profile_count &other) const | |
216 | { | |
217 | return initialized_p () && other.initialized_p () && m_val < other.m_val; | |
218 | } | |
219 | bool operator> (const profile_count &other) const | |
220 | { | |
221 | return initialized_p () && other.initialized_p () && m_val > other.m_val; | |
222 | } | |
223 | bool operator< (const gcov_type other) const | |
224 | { | |
4e9a497f JH |
225 | gcc_checking_assert (other >= 0); |
226 | return initialized_p () && m_val < (uint64_t) other; | |
3995f3a2 JH |
227 | } |
228 | bool operator> (const gcov_type other) const | |
229 | { | |
4e9a497f JH |
230 | gcc_checking_assert (other >= 0); |
231 | return initialized_p () && m_val > (uint64_t) other; | |
3995f3a2 JH |
232 | } |
233 | ||
234 | bool operator<= (const profile_count &other) const | |
235 | { | |
236 | return initialized_p () && other.initialized_p () && m_val <= other.m_val; | |
237 | } | |
238 | bool operator>= (const profile_count &other) const | |
239 | { | |
240 | return initialized_p () && m_val >= other.m_val; | |
241 | } | |
242 | bool operator<= (const gcov_type other) const | |
243 | { | |
4e9a497f JH |
244 | gcc_checking_assert (other >= 0); |
245 | return initialized_p () && m_val <= (uint64_t) other; | |
3995f3a2 JH |
246 | } |
247 | bool operator>= (const gcov_type other) const | |
248 | { | |
4e9a497f JH |
249 | gcc_checking_assert (other >= 0); |
250 | return initialized_p () && m_val >= (uint64_t) other; | |
3995f3a2 JH |
251 | } |
252 | ||
253 | /* PROB is a probability in scale 0...REG_BR_PROB_BASE. Scale counter | |
254 | accordingly. */ | |
255 | profile_count apply_probability (int prob) const | |
256 | { | |
257 | gcc_checking_assert (prob >= 0 && prob <= REG_BR_PROB_BASE); | |
eaee472d | 258 | if (m_val == 0) |
aea5e79a | 259 | return *this; |
3995f3a2 JH |
260 | if (!initialized_p ()) |
261 | return profile_count::uninitialized (); | |
262 | profile_count ret; | |
263 | ret.m_val = RDIV (m_val * prob, REG_BR_PROB_BASE); | |
4e9a497f | 264 | ret.m_quality = MIN (m_quality, count_adjusted); |
3995f3a2 JH |
265 | return ret; |
266 | } | |
267 | /* Return *THIS * NUM / DEN. */ | |
268 | profile_count apply_scale (int64_t num, int64_t den) const | |
269 | { | |
eaee472d | 270 | if (m_val == 0) |
aea5e79a | 271 | return *this; |
3995f3a2 JH |
272 | if (!initialized_p ()) |
273 | return profile_count::uninitialized (); | |
274 | profile_count ret; | |
eaee472d | 275 | gcc_checking_assert (num >= 0 && den > 0); |
3995f3a2 | 276 | /* FIXME: shrink wrapping violates this sanity check. */ |
eaee472d JH |
277 | gcc_checking_assert ((num <= REG_BR_PROB_BASE |
278 | || den <= REG_BR_PROB_BASE) || 1); | |
3995f3a2 | 279 | ret.m_val = RDIV (m_val * num, den); |
4e9a497f | 280 | ret.m_quality = MIN (m_quality, count_adjusted); |
3995f3a2 JH |
281 | return ret; |
282 | } | |
283 | profile_count apply_scale (profile_count num, profile_count den) const | |
284 | { | |
eaee472d JH |
285 | if (m_val == 0) |
286 | return *this; | |
287 | if (num.m_val == 0) | |
288 | return num; | |
3995f3a2 JH |
289 | if (!initialized_p () || !num.initialized_p () || !den.initialized_p ()) |
290 | return profile_count::uninitialized (); | |
3995f3a2 | 291 | gcc_checking_assert (den > 0); |
4e9a497f JH |
292 | if (num == den) |
293 | return *this; | |
294 | ||
295 | profile_count ret; | |
3995f3a2 JH |
296 | /* Take care for overflows! */ |
297 | if (num.m_val < max_safe_multiplier || m_val < max_safe_multiplier) | |
298 | ret.m_val = RDIV (m_val * num.m_val, den.m_val); | |
299 | else | |
300 | ret.m_val = RDIV (m_val * RDIV (num.m_val * max_safe_multiplier, | |
301 | den.m_val), max_safe_multiplier); | |
4e9a497f | 302 | ret.m_quality = MIN (m_quality, count_adjusted); |
3995f3a2 JH |
303 | return ret; |
304 | } | |
305 | ||
306 | /* Return probability of event with counter THIS within event with counter | |
307 | OVERALL. */ | |
308 | int probability_in (profile_count overall) | |
309 | { | |
eaee472d | 310 | if (!m_val) |
3995f3a2 JH |
311 | return 0; |
312 | if (!initialized_p () || !overall.initialized_p ()) | |
313 | return REG_BR_PROB_BASE / 2; | |
314 | if (overall < *this) | |
315 | return REG_BR_PROB_BASE; | |
316 | if (!overall.m_val) | |
317 | return REG_BR_PROB_BASE / 2; | |
318 | return RDIV (m_val * REG_BR_PROB_BASE, overall.m_val); | |
319 | } | |
320 | ||
321 | /* Output THIS to F. */ | |
322 | void dump (FILE *f) const; | |
323 | ||
324 | /* Print THIS to stderr. */ | |
325 | void debug () const; | |
326 | ||
327 | /* Return true if THIS is known to differ significantly from OTHER. */ | |
328 | bool differs_from_p (profile_count other) const; | |
329 | ||
330 | /* LTO streaming support. */ | |
331 | static profile_count stream_in (struct lto_input_block *); | |
332 | void stream_out (struct output_block *); | |
333 | void stream_out (struct lto_output_stream *); | |
334 | }; | |
335 | #endif |