interpreter/CallFrame.h

   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 "RegisterFile.h"
  28 #include "ScopeChain.h"
  29
  30 namespace JSC  {
  31
  32     class Arguments;
  33     class JSActivation;
  34     class Interpreter;
  35
  36     // Represents the current state of script execution.
  37     // Passed as the first argument to most functions.
  38     class ExecState : private Register {
  39     public:
  40         JSFunction* callee() const { return this[RegisterFile::Callee].function(); }
  41         CodeBlock* codeBlock() const { return this[RegisterFile::CodeBlock].Register::codeBlock(); }
  42         ScopeChainNode* scopeChain() const { return this[RegisterFile::ScopeChain].Register::scopeChain(); }
  43
  44         JSValuePtr thisValue();
  45
  46         // Global object in which execution began.
  47         JSGlobalObject* dynamicGlobalObject();
  48
  49         // Global object in which the currently executing code was defined.
  50         // Differs from dynamicGlobalObject() during function calls across web browser frames.
  51         JSGlobalObject* lexicalGlobalObject() const
  52         {
  53             return scopeChain()->globalObject();
  54         }
  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         JSObject* globalThisValue() const
  59         {
  60             return scopeChain()->globalThisObject();
  61         }
  62
  63         // FIXME: Elsewhere, we use JSGlobalData* rather than JSGlobalData&.
  64         // We should make this more uniform and either use a reference everywhere
  65         // or a pointer everywhere.
  66         JSGlobalData& globalData() const
  67         {
  68             return *scopeChain()->globalData;
  69         }
  70
  71         // Convenience functions for access to global data.
  72         // It takes a few memory references to get from a call frame to the global data
  73         // pointer, so these are inefficient, and should be used sparingly in new code.
  74         // But they're used in many places in legacy code, so they're not going away any time soon.
  75
  76         void setException(JSValuePtr exception) { globalData().exception = exception; }
  77         void clearException() { globalData().exception = noValue(); }
  78         JSValuePtr exception() const { return globalData().exception; }
  79         JSValuePtr* exceptionSlot() { return &globalData().exception; }
  80         bool hadException() const { return globalData().exception; }
  81
  82         const CommonIdentifiers& propertyNames() const { return *globalData().propertyNames; }
  83         const ArgList& emptyList() const { return *globalData().emptyList; }
  84         Interpreter* interpreter() { return globalData().interpreter; }
  85         Heap* heap() { return &globalData().heap; }
  86
  87         static const HashTable* arrayTable(CallFrame* callFrame) { return callFrame->globalData().arrayTable; }
  88         static const HashTable* dateTable(CallFrame* callFrame) { return callFrame->globalData().dateTable; }
  89         static const HashTable* mathTable(CallFrame* callFrame) { return callFrame->globalData().mathTable; }
  90         static const HashTable* numberTable(CallFrame* callFrame) { return callFrame->globalData().numberTable; }
  91         static const HashTable* regExpTable(CallFrame* callFrame) { return callFrame->globalData().regExpTable; }
  92         static const HashTable* regExpConstructorTable(CallFrame* callFrame) { return callFrame->globalData().regExpConstructorTable; }
  93         static const HashTable* stringTable(CallFrame* callFrame) { return callFrame->globalData().stringTable; }
  94
  95     private:
  96         friend class Arguments;
  97         friend class JSActivation;
  98         friend class JSGlobalObject;
  99         friend class Interpreter;
 100
 101         static CallFrame* create(Register* callFrameBase) { return static_cast<CallFrame*>(callFrameBase); }
 102         Register* registers() { return this; }
 103
 104         CallFrame& operator=(const Register& r) { *static_cast<Register*>(this) = r; return *this; }
 105
 106         int argumentCount() const { return this[RegisterFile::ArgumentCount].i(); }
 107         CallFrame* callerFrame() const { return this[RegisterFile::CallerFrame].callFrame(); }
 108         Arguments* optionalCalleeArguments() const { return this[RegisterFile::OptionalCalleeArguments].arguments(); }
 109         Instruction* returnPC() const { return this[RegisterFile::ReturnPC].vPC(); }
 110         int returnValueRegister() const { return this[RegisterFile::ReturnValueRegister].i(); }
 111
 112         void setArgumentCount(int count) { this[RegisterFile::ArgumentCount] = count; }
 113         void setCallee(JSFunction* callee) { this[RegisterFile::Callee] = callee; }
 114         void setCalleeArguments(Arguments* arguments) { this[RegisterFile::OptionalCalleeArguments] = arguments; }
 115         void setCallerFrame(CallFrame* callerFrame) { this[RegisterFile::CallerFrame] = callerFrame; }
 116         void setCodeBlock(CodeBlock* codeBlock) { this[RegisterFile::CodeBlock] = codeBlock; }
 117         void setScopeChain(ScopeChainNode* scopeChain) { this[RegisterFile::ScopeChain] = scopeChain; }
 118
 119         ALWAYS_INLINE void init(CodeBlock* codeBlock, Instruction* vPC, ScopeChainNode* scopeChain,
 120             CallFrame* callerFrame, int returnValueRegister, int argc, JSFunction* function)
 121         {
 122             ASSERT(callerFrame); // Use noCaller() rather than 0 for the outer host call frame caller.
 123
 124             setCodeBlock(codeBlock);
 125             setScopeChain(scopeChain);
 126             setCallerFrame(callerFrame);
 127             this[RegisterFile::ReturnPC] = vPC; // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*.
 128             this[RegisterFile::ReturnValueRegister] = returnValueRegister;
 129             setArgumentCount(argc); // original argument count (for the sake of the "arguments" object)
 130             setCallee(function);
 131             setCalleeArguments(0);
 132         }
 133
 134         static const intptr_t HostCallFrameFlag = 1;
 135
 136         static CallFrame* noCaller() { return reinterpret_cast<CallFrame*>(HostCallFrameFlag); }
 137         bool hasHostCallFrameFlag() const { return reinterpret_cast<intptr_t>(this) & HostCallFrameFlag; }
 138         CallFrame* addHostCallFrameFlag() const { return reinterpret_cast<CallFrame*>(reinterpret_cast<intptr_t>(this) | HostCallFrameFlag); }
 139         CallFrame* removeHostCallFrameFlag() { return reinterpret_cast<CallFrame*>(reinterpret_cast<intptr_t>(this) & ~HostCallFrameFlag); }
 140
 141         ExecState();
 142         ~ExecState();
 143     };
 144
 145 } // namespace JSC
 146
 147 #endif // CallFrame_h