1/*
2 * Copyright (C) 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 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef PolymorphicAccessStructureList_h
27#define PolymorphicAccessStructureList_h
28
29#include "JITStubRoutine.h"
30#include "Structure.h"
31#include "StructureChain.h"
32
33#define POLYMORPHIC_LIST_CACHE_SIZE 8
34
35namespace JSC {
36
37// *Sigh*, If the JIT is enabled we need to track the stubRountine (of type CodeLocationLabel),
38// If the JIT is not in use we don't actually need the variable (that said, if the JIT is not in use we don't
39// curently actually use PolymorphicAccessStructureLists, which we should).  Anyway, this seems like the best
40// solution for now - will need to something smarter if/when we actually want mixed-mode operation.
41
42#if ENABLE(JIT)
43// Structure used by op_get_by_id_self_list and op_get_by_id_proto_list instruction to hold data off the main opcode stream.
44struct PolymorphicAccessStructureList {
45    WTF_MAKE_FAST_ALLOCATED;
46public:
47    struct PolymorphicStubInfo {
48        bool isDirect : 1;
49        unsigned count : 31;
50        RefPtr<JITStubRoutine> stubRoutine;
51        WriteBarrier<Structure> base;
52        WriteBarrier<StructureChain> chain;
53
54        PolymorphicStubInfo()
55        {
56        }
57
58        void set(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> _stubRoutine, Structure* _base, bool _isDirect)
59        {
60            stubRoutine = _stubRoutine;
61            base.set(vm, owner, _base);
62            isDirect = _isDirect;
63            count = 0;
64        }
65
66        void set(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> _stubRoutine, Structure* _base, StructureChain* _chain, bool _isDirect, unsigned _count)
67        {
68            stubRoutine = _stubRoutine;
69            base.set(vm, owner, _base);
70            chain.set(vm, owner, _chain);
71            isDirect = _isDirect;
72            count = _count;
73        }
74    } list[POLYMORPHIC_LIST_CACHE_SIZE];
75
76    PolymorphicAccessStructureList()
77    {
78    }
79
80    PolymorphicAccessStructureList(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> stubRoutine, Structure* firstBase, bool isDirect)
81    {
82        list[0].set(vm, owner, stubRoutine, firstBase, isDirect);
83    }
84
85    PolymorphicAccessStructureList(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> stubRoutine, Structure* firstBase, StructureChain* firstChain, bool isDirect, unsigned count)
86    {
87        list[0].set(vm, owner, stubRoutine, firstBase, firstChain, isDirect, count);
88    }
89
90    bool visitWeak(int count)
91    {
92        for (int i = 0; i < count; ++i) {
93            PolymorphicStubInfo& info = list[i];
94            if (!info.base)
95                continue;
96
97            if (!Heap::isMarked(info.base.get()))
98                return false;
99            if (info.chain && !Heap::isMarked(info.chain.get()))
100                return false;
101        }
102
103        return true;
104    }
105};
106
107#endif // ENABLE(JIT)
108
109} // namespace JSC
110
111#endif // PolymorphicAccessStructureList_h
112
113