1/*
2 *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
3 *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
4 *  Copyright (C) 2003, 2007, 2008 Apple Inc. All rights reserved.
5 *
6 *  This library is free software; you can redistribute it and/or
7 *  modify it under the terms of the GNU Library General Public
8 *  License as published by the Free Software Foundation; either
9 *  version 2 of the License, or (at your option) any later version.
10 *
11 *  This library is distributed in the hope that it will be useful,
12 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 *  Library General Public License for more details.
15 *
16 *  You should have received a copy of the GNU Library General Public License
17 *  along with this library; see the file COPYING.LIB.  If not, write to
18 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
19 *  Boston, MA 02110-1301, USA.
20 *
21 */
22
23#ifndef CallFrame_h
24#define CallFrame_h
25
26#include "JSGlobalData.h"
27#include "MacroAssemblerCodeRef.h"
28#include "RegisterFile.h"
29
30namespace JSC  {
31
32    class Arguments;
33    class JSActivation;
34    class Interpreter;
35    class ScopeChainNode;
36
37    // Represents the current state of script execution.
38    // Passed as the first argument to most functions.
39    class ExecState : private Register {
40    public:
41        JSObject* callee() const { return this[RegisterFile::Callee].function(); }
42        CodeBlock* codeBlock() const { return this[RegisterFile::CodeBlock].Register::codeBlock(); }
43        ScopeChainNode* scopeChain() const
44        {
45            ASSERT(this[RegisterFile::ScopeChain].Register::scopeChain());
46            return this[RegisterFile::ScopeChain].Register::scopeChain();
47        }
48
49        // Global object in which execution began.
50        JSGlobalObject* dynamicGlobalObject();
51
52        // Global object in which the currently executing code was defined.
53        // Differs from dynamicGlobalObject() during function calls across web browser frames.
54        inline JSGlobalObject* lexicalGlobalObject() const;
55
56        // Differs from lexicalGlobalObject because this will have DOM window shell rather than
57        // the actual DOM window, which can't be "this" for security reasons.
58        inline JSObject* globalThisValue() const;
59
60        inline JSGlobalData& globalData() const;
61
62        // Convenience functions for access to global data.
63        // It takes a few memory references to get from a call frame to the global data
64        // pointer, so these are inefficient, and should be used sparingly in new code.
65        // But they're used in many places in legacy code, so they're not going away any time soon.
66
67        void clearException() { globalData().exception = JSValue(); }
68        JSValue exception() const { return globalData().exception; }
69        bool hadException() const { return globalData().exception; }
70
71        const CommonIdentifiers& propertyNames() const { return *globalData().propertyNames; }
72        const MarkedArgumentBuffer& emptyList() const { return *globalData().emptyList; }
73        Interpreter* interpreter() { return globalData().interpreter; }
74        Heap* heap() { return &globalData().heap; }
75#ifndef NDEBUG
76        void dumpCaller();
77#endif
78        static const HashTable* arrayTable(CallFrame* callFrame) { return callFrame->globalData().arrayTable; }
79        static const HashTable* dateTable(CallFrame* callFrame) { return callFrame->globalData().dateTable; }
80        static const HashTable* jsonTable(CallFrame* callFrame) { return callFrame->globalData().jsonTable; }
81        static const HashTable* mathTable(CallFrame* callFrame) { return callFrame->globalData().mathTable; }
82        static const HashTable* numberTable(CallFrame* callFrame) { return callFrame->globalData().numberTable; }
83        static const HashTable* objectConstructorTable(CallFrame* callFrame) { return callFrame->globalData().objectConstructorTable; }
84        static const HashTable* regExpTable(CallFrame* callFrame) { return callFrame->globalData().regExpTable; }
85        static const HashTable* regExpConstructorTable(CallFrame* callFrame) { return callFrame->globalData().regExpConstructorTable; }
86        static const HashTable* stringTable(CallFrame* callFrame) { return callFrame->globalData().stringTable; }
87
88        static CallFrame* create(Register* callFrameBase) { return static_cast<CallFrame*>(callFrameBase); }
89        Register* registers() { return this; }
90
91        CallFrame& operator=(const Register& r) { *static_cast<Register*>(this) = r; return *this; }
92
93        CallFrame* callerFrame() const { return this[RegisterFile::CallerFrame].callFrame(); }
94#if ENABLE(JIT)
95        ReturnAddressPtr returnPC() const { return ReturnAddressPtr(this[RegisterFile::ReturnPC].vPC()); }
96#endif
97#if ENABLE(INTERPRETER)
98        Instruction* returnVPC() const { return this[RegisterFile::ReturnPC].vPC(); }
99#endif
100
101        void setCallerFrame(CallFrame* callerFrame) { static_cast<Register*>(this)[RegisterFile::CallerFrame] = callerFrame; }
102        void setScopeChain(ScopeChainNode* scopeChain) { static_cast<Register*>(this)[RegisterFile::ScopeChain] = scopeChain; }
103
104        ALWAYS_INLINE void init(CodeBlock* codeBlock, Instruction* vPC, ScopeChainNode* scopeChain,
105            CallFrame* callerFrame, int argc, JSObject* callee)
106        {
107            ASSERT(callerFrame); // Use noCaller() rather than 0 for the outer host call frame caller.
108            ASSERT(callerFrame == noCaller() || callerFrame->removeHostCallFrameFlag()->registerFile()->end() >= this);
109
110            setCodeBlock(codeBlock);
111            setScopeChain(scopeChain);
112            setCallerFrame(callerFrame);
113            setReturnPC(vPC); // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*.
114            setArgumentCountIncludingThis(argc); // original argument count (for the sake of the "arguments" object)
115            setCallee(callee);
116        }
117
118        // Read a register from the codeframe (or constant from the CodeBlock).
119        inline Register& r(int);
120        // Read a register for a non-constant
121        inline Register& uncheckedR(int);
122
123        // Access to arguments.
124        int hostThisRegister() { return -RegisterFile::CallFrameHeaderSize - argumentCountIncludingThis(); }
125        JSValue hostThisValue() { return this[hostThisRegister()].jsValue(); }
126        size_t argumentCount() const { return argumentCountIncludingThis() - 1; }
127        size_t argumentCountIncludingThis() const { return this[RegisterFile::ArgumentCount].i(); }
128        JSValue argument(int argumentNumber)
129        {
130            int argumentIndex = -RegisterFile::CallFrameHeaderSize - this[RegisterFile::ArgumentCount].i() + argumentNumber + 1;
131            if (argumentIndex >= -RegisterFile::CallFrameHeaderSize)
132                return jsUndefined();
133            return this[argumentIndex].jsValue();
134        }
135
136        static CallFrame* noCaller() { return reinterpret_cast<CallFrame*>(HostCallFrameFlag); }
137
138        bool hasHostCallFrameFlag() const { return reinterpret_cast<intptr_t>(this) & HostCallFrameFlag; }
139        CallFrame* addHostCallFrameFlag() const { return reinterpret_cast<CallFrame*>(reinterpret_cast<intptr_t>(this) | HostCallFrameFlag); }
140        CallFrame* removeHostCallFrameFlag() { return reinterpret_cast<CallFrame*>(reinterpret_cast<intptr_t>(this) & ~HostCallFrameFlag); }
141
142        void setArgumentCountIncludingThis(int count) { static_cast<Register*>(this)[RegisterFile::ArgumentCount] = Register::withInt(count); }
143        void setCallee(JSObject* callee) { static_cast<Register*>(this)[RegisterFile::Callee] = Register::withCallee(callee); }
144        void setCodeBlock(CodeBlock* codeBlock) { static_cast<Register*>(this)[RegisterFile::CodeBlock] = codeBlock; }
145        void setReturnPC(void* value) { static_cast<Register*>(this)[RegisterFile::ReturnPC] = (Instruction*)value; }
146
147    private:
148        static const intptr_t HostCallFrameFlag = 1;
149#ifndef NDEBUG
150        RegisterFile* registerFile();
151#endif
152        ExecState();
153        ~ExecState();
154    };
155
156} // namespace JSC
157
158#endif // CallFrame_h
159