1/*
2 * Copyright (C) 2008-2019 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 "DirectEvalExecutable.h"
32#include <wtf/HashMap.h>
33#include <wtf/RefPtr.h>
34#include <wtf/text/StringHash.h>
35
36namespace JSC {
37
38 class SlotVisitor;
39
40 class DirectEvalCodeCache {
41 public:
42 class CacheKey {
43 public:
44 CacheKey(const String& source, CallSiteIndex callSiteIndex)
45 : m_source(source.impl())
46 , m_callSiteIndex(callSiteIndex)
47 {
48 }
49
50 CacheKey(WTF::HashTableDeletedValueType)
51 : m_source(WTF::HashTableDeletedValue)
52 {
53 }
54
55 CacheKey() = default;
56
57 unsigned hash() const { return m_source->hash() ^ m_callSiteIndex.bits(); }
58
59 bool isEmptyValue() const { return !m_source; }
60
61 bool operator==(const CacheKey& other) const
62 {
63 return m_callSiteIndex == other.m_callSiteIndex && WTF::equal(m_source.get(), other.m_source.get());
64 }
65
66 bool isHashTableDeletedValue() const { return m_source.isHashTableDeletedValue(); }
67
68 struct Hash {
69 static unsigned hash(const CacheKey& key)
70 {
71 return key.hash();
72 }
73 static bool equal(const CacheKey& lhs, const CacheKey& rhs)
74 {
75 return lhs == rhs;
76 }
77 static constexpr bool safeToCompareToEmptyOrDeleted = false;
78 };
79
80 typedef SimpleClassHashTraits<CacheKey> HashTraits;
81
82 private:
83 RefPtr<StringImpl> m_source;
84 CallSiteIndex m_callSiteIndex;
85 };
86
87 DirectEvalExecutable* tryGet(const String& evalSource, CallSiteIndex callSiteIndex)
88 {
89 return m_cacheMap.inlineGet(CacheKey(evalSource, callSiteIndex)).get();
90 }
91
92 void set(JSGlobalObject* globalObject, JSCell* owner, const String& evalSource, CallSiteIndex callSiteIndex, DirectEvalExecutable* evalExecutable)
93 {
94 if (m_cacheMap.size() < maxCacheEntries)
95 setSlow(globalObject, owner, evalSource, callSiteIndex, evalExecutable);
96 }
97
98 bool isEmpty() const { return m_cacheMap.isEmpty(); }
99
100 void visitAggregate(SlotVisitor&);
101
102 void clear();
103
104 private:
105 static constexpr int maxCacheEntries = 64;
106
107 void setSlow(JSGlobalObject*, JSCell* owner, const String& evalSource, CallSiteIndex, DirectEvalExecutable*);
108
109 typedef HashMap<CacheKey, WriteBarrier<DirectEvalExecutable>, CacheKey::Hash, CacheKey::HashTraits> EvalCacheMap;
110 EvalCacheMap m_cacheMap;
111 Lock m_lock;
112 };
113
114} // namespace JSC
115