1/*
2 * Copyright (C) 2011, 2012, 2013 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 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 "ConcurrentJITLock.h"
33#include "Heap.h"
34#include "JSArray.h"
35#include "SpeculatedType.h"
36#include "Structure.h"
37#include "WriteBarrier.h"
38#include <wtf/PrintStream.h>
39#include <wtf/StringPrintStream.h>
40
41namespace JSC {
42
43template<unsigned numberOfBucketsArgument>
44struct ValueProfileBase {
45    static const unsigned numberOfBuckets = numberOfBucketsArgument;
46    static const unsigned numberOfSpecFailBuckets = 1;
47    static const unsigned bucketIndexMask = numberOfBuckets - 1;
48    static const unsigned totalNumberOfBuckets = numberOfBuckets + numberOfSpecFailBuckets;
49
50    ValueProfileBase()
51        : m_bytecodeOffset(-1)
52        , m_prediction(SpecNone)
53        , m_numberOfSamplesInPrediction(0)
54    {
55        for (unsigned i = 0; i < totalNumberOfBuckets; ++i)
56            m_buckets[i] = JSValue::encode(JSValue());
57    }
58
59    ValueProfileBase(int bytecodeOffset)
60        : m_bytecodeOffset(bytecodeOffset)
61        , m_prediction(SpecNone)
62        , m_numberOfSamplesInPrediction(0)
63    {
64        for (unsigned i = 0; i < totalNumberOfBuckets; ++i)
65            m_buckets[i] = JSValue::encode(JSValue());
66    }
67
68    EncodedJSValue* specFailBucket(unsigned i)
69    {
70        ASSERT(numberOfBuckets + i < totalNumberOfBuckets);
71        return m_buckets + numberOfBuckets + i;
72    }
73
74    const ClassInfo* classInfo(unsigned bucket) const
75    {
76        JSValue value = JSValue::decode(m_buckets[bucket]);
77        if (!!value) {
78            if (!value.isCell())
79                return 0;
80            return value.asCell()->structure()->classInfo();
81        }
82        return 0;
83    }
84
85    unsigned numberOfSamples() const
86    {
87        unsigned result = 0;
88        for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
89            if (!!JSValue::decode(m_buckets[i]))
90                result++;
91        }
92        return result;
93    }
94
95    unsigned totalNumberOfSamples() const
96    {
97        return numberOfSamples() + m_numberOfSamplesInPrediction;
98    }
99
100    bool isLive() const
101    {
102        for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
103            if (!!JSValue::decode(m_buckets[i]))
104                return true;
105        }
106        return false;
107    }
108
109    CString briefDescription(const ConcurrentJITLocker& locker)
110    {
111        computeUpdatedPrediction(locker);
112
113        StringPrintStream out;
114        out.print("predicting ", SpeculationDump(m_prediction));
115        return out.toCString();
116    }
117
118    void dump(PrintStream& out)
119    {
120        out.print("samples = ", totalNumberOfSamples(), " prediction = ", SpeculationDump(m_prediction));
121        bool first = true;
122        for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
123            JSValue value = JSValue::decode(m_buckets[i]);
124            if (!!value) {
125                if (first) {
126                    out.printf(": ");
127                    first = false;
128                } else
129                    out.printf(", ");
130                out.print(value);
131            }
132        }
133    }
134
135    // Updates the prediction and returns the new one. Never call this from any thread
136    // that isn't executing the code.
137    SpeculatedType computeUpdatedPrediction(const ConcurrentJITLocker&)
138    {
139        for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
140            JSValue value = JSValue::decode(m_buckets[i]);
141            if (!value)
142                continue;
143
144            m_numberOfSamplesInPrediction++;
145            mergeSpeculation(m_prediction, speculationFromValue(value));
146
147            m_buckets[i] = JSValue::encode(JSValue());
148        }
149
150        return m_prediction;
151    }
152
153    int m_bytecodeOffset; // -1 for prologue
154
155    SpeculatedType m_prediction;
156    unsigned m_numberOfSamplesInPrediction;
157
158    EncodedJSValue m_buckets[totalNumberOfBuckets];
159};
160
161struct MinimalValueProfile : public ValueProfileBase<0> {
162    MinimalValueProfile(): ValueProfileBase<0>() { }
163    MinimalValueProfile(int bytecodeOffset): ValueProfileBase<0>(bytecodeOffset) { }
164};
165
166template<unsigned logNumberOfBucketsArgument>
167struct ValueProfileWithLogNumberOfBuckets : public ValueProfileBase<1 << logNumberOfBucketsArgument> {
168    static const unsigned logNumberOfBuckets = logNumberOfBucketsArgument;
169
170    ValueProfileWithLogNumberOfBuckets()
171        : ValueProfileBase<1 << logNumberOfBucketsArgument>()
172    {
173    }
174    ValueProfileWithLogNumberOfBuckets(int bytecodeOffset)
175        : ValueProfileBase<1 << logNumberOfBucketsArgument>(bytecodeOffset)
176    {
177    }
178};
179
180struct ValueProfile : public ValueProfileWithLogNumberOfBuckets<0> {
181    ValueProfile(): ValueProfileWithLogNumberOfBuckets<0>() { }
182    ValueProfile(int bytecodeOffset): ValueProfileWithLogNumberOfBuckets<0>(bytecodeOffset) { }
183};
184
185template<typename T>
186inline int getValueProfileBytecodeOffset(T* valueProfile)
187{
188    return valueProfile->m_bytecodeOffset;
189}
190
191// This is a mini value profile to catch pathologies. It is a counter that gets
192// incremented when we take the slow path on any instruction.
193struct RareCaseProfile {
194    RareCaseProfile(int bytecodeOffset)
195        : m_bytecodeOffset(bytecodeOffset)
196        , m_counter(0)
197    {
198    }
199
200    int m_bytecodeOffset;
201    uint32_t m_counter;
202};
203
204inline int getRareCaseProfileBytecodeOffset(RareCaseProfile* rareCaseProfile)
205{
206    return rareCaseProfile->m_bytecodeOffset;
207}
208
209} // namespace JSC
210
211#endif // ValueProfile_h
212
213