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1 /*
2 * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
14 * its contributors may be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #ifndef ValueProfile_h
30 #define ValueProfile_h
31
32 #include <wtf/Platform.h>
33
34 #if ENABLE(VALUE_PROFILER)
35
36 #include "Heap.h"
37 #include "JSArray.h"
38 #include "SpeculatedType.h"
39 #include "Structure.h"
40 #include "WriteBarrier.h"
41 #include <wtf/PrintStream.h>
42 #include <wtf/StringPrintStream.h>
43
44 namespace JSC {
45
46 template<unsigned numberOfBucketsArgument>
47 struct ValueProfileBase {
48 static const unsigned numberOfBuckets = numberOfBucketsArgument;
49 static const unsigned numberOfSpecFailBuckets = 1;
50 static const unsigned bucketIndexMask = numberOfBuckets - 1;
51 static const unsigned totalNumberOfBuckets = numberOfBuckets + numberOfSpecFailBuckets;
52
53 ValueProfileBase()
54 : m_bytecodeOffset(-1)
55 , m_prediction(SpecNone)
56 , m_numberOfSamplesInPrediction(0)
57 , m_singletonValueIsTop(false)
58 {
59 for (unsigned i = 0; i < totalNumberOfBuckets; ++i)
60 m_buckets[i] = JSValue::encode(JSValue());
61 }
62
63 ValueProfileBase(int bytecodeOffset)
64 : m_bytecodeOffset(bytecodeOffset)
65 , m_prediction(SpecNone)
66 , m_numberOfSamplesInPrediction(0)
67 , m_singletonValueIsTop(false)
68 {
69 for (unsigned i = 0; i < totalNumberOfBuckets; ++i)
70 m_buckets[i] = JSValue::encode(JSValue());
71 }
72
73 EncodedJSValue* specFailBucket(unsigned i)
74 {
75 ASSERT(numberOfBuckets + i < totalNumberOfBuckets);
76 return m_buckets + numberOfBuckets + i;
77 }
78
79 const ClassInfo* classInfo(unsigned bucket) const
80 {
81 JSValue value = JSValue::decode(m_buckets[bucket]);
82 if (!!value) {
83 if (!value.isCell())
84 return 0;
85 return value.asCell()->structure()->classInfo();
86 }
87 return 0;
88 }
89
90 unsigned numberOfSamples() const
91 {
92 unsigned result = 0;
93 for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
94 if (!!JSValue::decode(m_buckets[i]))
95 result++;
96 }
97 return result;
98 }
99
100 unsigned totalNumberOfSamples() const
101 {
102 return numberOfSamples() + m_numberOfSamplesInPrediction;
103 }
104
105 bool isLive() const
106 {
107 for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
108 if (!!JSValue::decode(m_buckets[i]))
109 return true;
110 }
111 return false;
112 }
113
114 CString briefDescription()
115 {
116 computeUpdatedPrediction();
117
118 StringPrintStream out;
119
120 if (m_singletonValueIsTop)
121 out.print("predicting ", SpeculationDump(m_prediction));
122 else if (m_singletonValue)
123 out.print("predicting ", m_singletonValue);
124
125 return out.toCString();
126 }
127
128 void dump(PrintStream& out)
129 {
130 out.print("samples = ", totalNumberOfSamples(), " prediction = ", SpeculationDump(m_prediction));
131 out.printf(", value = ");
132 if (m_singletonValueIsTop)
133 out.printf("TOP");
134 else
135 out.print(m_singletonValue);
136 bool first = true;
137 for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
138 JSValue value = JSValue::decode(m_buckets[i]);
139 if (!!value) {
140 if (first) {
141 out.printf(": ");
142 first = false;
143 } else
144 out.printf(", ");
145 out.print(value);
146 }
147 }
148 }
149
150 // Updates the prediction and returns the new one.
151 SpeculatedType computeUpdatedPrediction(OperationInProgress operation = NoOperation)
152 {
153 for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
154 JSValue value = JSValue::decode(m_buckets[i]);
155 if (!value)
156 continue;
157
158 m_numberOfSamplesInPrediction++;
159 mergeSpeculation(m_prediction, speculationFromValue(value));
160
161 if (!m_singletonValueIsTop && !!value) {
162 if (!m_singletonValue)
163 m_singletonValue = value;
164 else if (m_singletonValue != value)
165 m_singletonValueIsTop = true;
166 }
167
168 m_buckets[i] = JSValue::encode(JSValue());
169 }
170
171 if (operation == Collection
172 && !m_singletonValueIsTop
173 && !!m_singletonValue
174 && m_singletonValue.isCell()
175 && !Heap::isMarked(m_singletonValue.asCell()))
176 m_singletonValueIsTop = true;
177
178 return m_prediction;
179 }
180
181 int m_bytecodeOffset; // -1 for prologue
182
183 SpeculatedType m_prediction;
184 unsigned m_numberOfSamplesInPrediction;
185
186 bool m_singletonValueIsTop;
187 JSValue m_singletonValue;
188
189 EncodedJSValue m_buckets[totalNumberOfBuckets];
190 };
191
192 struct MinimalValueProfile : public ValueProfileBase<0> {
193 MinimalValueProfile(): ValueProfileBase<0>() { }
194 MinimalValueProfile(int bytecodeOffset): ValueProfileBase<0>(bytecodeOffset) { }
195 };
196
197 template<unsigned logNumberOfBucketsArgument>
198 struct ValueProfileWithLogNumberOfBuckets : public ValueProfileBase<1 << logNumberOfBucketsArgument> {
199 static const unsigned logNumberOfBuckets = logNumberOfBucketsArgument;
200
201 ValueProfileWithLogNumberOfBuckets()
202 : ValueProfileBase<1 << logNumberOfBucketsArgument>()
203 {
204 }
205 ValueProfileWithLogNumberOfBuckets(int bytecodeOffset)
206 : ValueProfileBase<1 << logNumberOfBucketsArgument>(bytecodeOffset)
207 {
208 }
209 };
210
211 struct ValueProfile : public ValueProfileWithLogNumberOfBuckets<0> {
212 ValueProfile(): ValueProfileWithLogNumberOfBuckets<0>() { }
213 ValueProfile(int bytecodeOffset): ValueProfileWithLogNumberOfBuckets<0>(bytecodeOffset) { }
214 };
215
216 template<typename T>
217 inline int getValueProfileBytecodeOffset(T* valueProfile)
218 {
219 return valueProfile->m_bytecodeOffset;
220 }
221
222 // This is a mini value profile to catch pathologies. It is a counter that gets
223 // incremented when we take the slow path on any instruction.
224 struct RareCaseProfile {
225 RareCaseProfile(int bytecodeOffset)
226 : m_bytecodeOffset(bytecodeOffset)
227 , m_counter(0)
228 {
229 }
230
231 int m_bytecodeOffset;
232 uint32_t m_counter;
233 };
234
235 inline int getRareCaseProfileBytecodeOffset(RareCaseProfile* rareCaseProfile)
236 {
237 return rareCaseProfile->m_bytecodeOffset;
238 }
239
240 } // namespace JSC
241
242 #endif // ENABLE(VALUE_PROFILER)
243
244 #endif // ValueProfile_h
245