1/*
2 * Copyright (C) 2011-2019 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#pragma once
30
31#include "ConcurrentJSLock.h"
32#include "SpeculatedType.h"
33#include "Structure.h"
34#include <wtf/PrintStream.h>
35#include <wtf/StringPrintStream.h>
36
37namespace JSC {
38
39template<unsigned numberOfBucketsArgument>
40struct ValueProfileBase {
41 static constexpr unsigned numberOfBuckets = numberOfBucketsArgument;
42 static constexpr unsigned numberOfSpecFailBuckets = 1;
43 static constexpr unsigned bucketIndexMask = numberOfBuckets - 1;
44 static constexpr unsigned totalNumberOfBuckets = numberOfBuckets + numberOfSpecFailBuckets;
45
46 ValueProfileBase()
47 {
48 for (unsigned i = 0; i < totalNumberOfBuckets; ++i)
49 m_buckets[i] = JSValue::encode(JSValue());
50 }
51
52 EncodedJSValue* specFailBucket(unsigned i)
53 {
54 ASSERT(numberOfBuckets + i < totalNumberOfBuckets);
55 return m_buckets + numberOfBuckets + i;
56 }
57
58 const ClassInfo* classInfo(unsigned bucket) const
59 {
60 JSValue value = JSValue::decode(m_buckets[bucket]);
61 if (!!value) {
62 if (!value.isCell())
63 return 0;
64 return value.asCell()->structure()->classInfo();
65 }
66 return 0;
67 }
68
69 unsigned numberOfSamples() const
70 {
71 unsigned result = 0;
72 for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
73 if (!!JSValue::decode(m_buckets[i]))
74 result++;
75 }
76 return result;
77 }
78
79 unsigned totalNumberOfSamples() const
80 {
81 return numberOfSamples() + isSampledBefore();
82 }
83
84 bool isSampledBefore() const { return m_prediction != SpecNone; }
85
86 bool isLive() const
87 {
88 for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
89 if (!!JSValue::decode(m_buckets[i]))
90 return true;
91 }
92 return false;
93 }
94
95 CString briefDescription(const ConcurrentJSLocker& locker)
96 {
97 computeUpdatedPrediction(locker);
98
99 StringPrintStream out;
100 out.print("predicting ", SpeculationDump(m_prediction));
101 return out.toCString();
102 }
103
104 void dump(PrintStream& out)
105 {
106 out.print("sampled before = ", isSampledBefore(), " live samples = ", numberOfSamples(), " prediction = ", SpeculationDump(m_prediction));
107 bool first = true;
108 for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
109 JSValue value = JSValue::decode(m_buckets[i]);
110 if (!!value) {
111 if (first) {
112 out.printf(": ");
113 first = false;
114 } else
115 out.printf(", ");
116 out.print(value);
117 }
118 }
119 }
120
121 // Updates the prediction and returns the new one. Never call this from any thread
122 // that isn't executing the code.
123 SpeculatedType computeUpdatedPrediction(const ConcurrentJSLocker&)
124 {
125 for (unsigned i = 0; i < totalNumberOfBuckets; ++i) {
126 JSValue value = JSValue::decode(m_buckets[i]);
127 if (!value)
128 continue;
129
130 mergeSpeculation(m_prediction, speculationFromValue(value));
131
132 m_buckets[i] = JSValue::encode(JSValue());
133 }
134
135 return m_prediction;
136 }
137
138 EncodedJSValue m_buckets[totalNumberOfBuckets];
139
140 SpeculatedType m_prediction { SpecNone };
141};
142
143struct MinimalValueProfile : public ValueProfileBase<0> {
144 MinimalValueProfile(): ValueProfileBase<0>() { }
145};
146
147template<unsigned logNumberOfBucketsArgument>
148struct ValueProfileWithLogNumberOfBuckets : public ValueProfileBase<1 << logNumberOfBucketsArgument> {
149 static constexpr unsigned logNumberOfBuckets = logNumberOfBucketsArgument;
150
151 ValueProfileWithLogNumberOfBuckets()
152 : ValueProfileBase<1 << logNumberOfBucketsArgument>()
153 {
154 }
155};
156
157struct ValueProfile : public ValueProfileWithLogNumberOfBuckets<0> {
158 ValueProfile() : ValueProfileWithLogNumberOfBuckets<0>() { }
159};
160
161// This is a mini value profile to catch pathologies. It is a counter that gets
162// incremented when we take the slow path on any instruction.
163struct RareCaseProfile {
164 RareCaseProfile(BytecodeIndex bytecodeIndex)
165 : m_bytecodeIndex(bytecodeIndex)
166 , m_counter(0)
167 {
168 }
169
170 BytecodeIndex m_bytecodeIndex;
171 uint32_t m_counter;
172};
173
174inline BytecodeIndex getRareCaseProfileBytecodeIndex(RareCaseProfile* rareCaseProfile)
175{
176 return rareCaseProfile->m_bytecodeIndex;
177}
178
179struct ValueProfileAndOperand : public ValueProfile {
180 int m_operand;
181};
182
183struct ValueProfileAndOperandBuffer {
184 WTF_MAKE_STRUCT_FAST_ALLOCATED;
185
186 ValueProfileAndOperandBuffer(unsigned size)
187 : m_size(size)
188 {
189 // FIXME: ValueProfile has more stuff than we need. We could optimize these value profiles
190 // to be more space efficient.
191 // https://bugs.webkit.org/show_bug.cgi?id=175413
192 m_buffer = MallocPtr<ValueProfileAndOperand>::malloc(m_size * sizeof(ValueProfileAndOperand));
193 for (unsigned i = 0; i < m_size; ++i)
194 new (&m_buffer.get()[i]) ValueProfileAndOperand();
195 }
196
197 ~ValueProfileAndOperandBuffer()
198 {
199 for (unsigned i = 0; i < m_size; ++i)
200 m_buffer.get()[i].~ValueProfileAndOperand();
201 }
202
203 template <typename Function>
204 void forEach(Function function)
205 {
206 for (unsigned i = 0; i < m_size; ++i)
207 function(m_buffer.get()[i]);
208 }
209
210 unsigned m_size;
211 MallocPtr<ValueProfileAndOperand> m_buffer;
212};
213
214} // namespace JSC
215