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 #include "ScopeChain.h"

    30 

    31 namespace JSC  {

    32 

    33     class Arguments;

    34     class JSActivation;

    35     class Interpreter;

    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         JSGlobalObject* lexicalGlobalObject() const

    55         {

    56             return scopeChain()->globalObject;

    57         }

    58 

    59         // Differs from lexicalGlobalObject because this will have DOM window shell rather than

    60         // the actual DOM window, which can't be "this" for security reasons.

    61         JSObject* globalThisValue() const

    62         {

    63             return scopeChain()->globalThis;

    64         }

    65 

    66         // FIXME: Elsewhere, we use JSGlobalData* rather than JSGlobalData&.

    67         // We should make this more uniform and either use a reference everywhere

    68         // or a pointer everywhere.

    69         JSGlobalData& globalData() const

    70         {

    71             ASSERT(scopeChain()->globalData);

    72             return *scopeChain()->globalData;

    73         }

    74 

    75         // Convenience functions for access to global data.

    76         // It takes a few memory references to get from a call frame to the global data

    77         // pointer, so these are inefficient, and should be used sparingly in new code.

    78         // But they're used in many places in legacy code, so they're not going away any time soon.

    79 

    80         void clearException() { globalData().exception = JSValue(); }

    81         JSValue exception() const { return globalData().exception; }

    82         JSValue* exceptionSlot() { return &globalData().exception; }

    83         bool hadException() const { return globalData().exception; }

    84 

    85         const CommonIdentifiers& propertyNames() const { return *globalData().propertyNames; }

    86         const MarkedArgumentBuffer& emptyList() const { return *globalData().emptyList; }

    87         Interpreter* interpreter() { return globalData().interpreter; }

    88         Heap* heap() { return &globalData().heap; }

    89 #ifndef NDEBUG

    90         void dumpCaller();

    91 #endif

    92         static const HashTable* arrayTable(CallFrame* callFrame) { return callFrame->globalData().arrayTable; }

    93         static const HashTable* dateTable(CallFrame* callFrame) { return callFrame->globalData().dateTable; }

    94         static const HashTable* jsonTable(CallFrame* callFrame) { return callFrame->globalData().jsonTable; }

    95         static const HashTable* mathTable(CallFrame* callFrame) { return callFrame->globalData().mathTable; }

    96         static const HashTable* numberTable(CallFrame* callFrame) { return callFrame->globalData().numberTable; }

    97         static const HashTable* regExpTable(CallFrame* callFrame) { return callFrame->globalData().regExpTable; }

    98         static const HashTable* regExpConstructorTable(CallFrame* callFrame) { return callFrame->globalData().regExpConstructorTable; }

    99         static const HashTable* stringTable(CallFrame* callFrame) { return callFrame->globalData().stringTable; }

   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         CallFrame* callerFrame() const { return this[RegisterFile::CallerFrame].callFrame(); }

   107 #if ENABLE(JIT)

   108         ReturnAddressPtr returnPC() const { return ReturnAddressPtr(this[RegisterFile::ReturnPC].vPC()); }

   109 #endif

   110 #if ENABLE(INTERPRETER)

   111         Instruction* returnVPC() const { return this[RegisterFile::ReturnPC].vPC(); }

   112 #endif

   113 

   114         void setCallerFrame(CallFrame* callerFrame) { static_cast<Register*>(this)[RegisterFile::CallerFrame] = callerFrame; }

   115         void setScopeChain(ScopeChainNode* scopeChain) { static_cast<Register*>(this)[RegisterFile::ScopeChain] = scopeChain; }

   116 

   117         ALWAYS_INLINE void init(CodeBlock* codeBlock, Instruction* vPC, ScopeChainNode* scopeChain,

   118             CallFrame* callerFrame, int argc, JSObject* callee)

   119         {

   120             ASSERT(callerFrame); // Use noCaller() rather than 0 for the outer host call frame caller.

   121             ASSERT(callerFrame == noCaller() || callerFrame->removeHostCallFrameFlag()->registerFile()->end() >= this);

   122 

   123             setCodeBlock(codeBlock);

   124             setScopeChain(scopeChain);

   125             setCallerFrame(callerFrame);

   126             setReturnPC(vPC); // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*.

   127             setArgumentCountIncludingThis(argc); // original argument count (for the sake of the "arguments" object)

   128             setCallee(callee);

   129         }

   130 

   131         // Read a register from the codeframe (or constant from the CodeBlock).

   132         inline Register& r(int);

   133 

   134         // Access to arguments.

   135         int hostThisRegister() { return -RegisterFile::CallFrameHeaderSize - argumentCountIncludingThis(); }

   136         JSValue hostThisValue() { return this[hostThisRegister()].jsValue(); }

   137         size_t argumentCount() const { return argumentCountIncludingThis() - 1; }

   138         size_t argumentCountIncludingThis() const { return this[RegisterFile::ArgumentCount].i(); }

   139         JSValue argument(int argumentNumber)

   140         {

   141             int argumentIndex = -RegisterFile::CallFrameHeaderSize - this[RegisterFile::ArgumentCount].i() + argumentNumber + 1;

   142             if (argumentIndex >= -RegisterFile::CallFrameHeaderSize)

   143                 return jsUndefined();

   144             return this[argumentIndex].jsValue();

   145         }

   146 

   147         static CallFrame* noCaller() { return reinterpret_cast<CallFrame*>(HostCallFrameFlag); }

   148 

   149         bool hasHostCallFrameFlag() const { return reinterpret_cast<intptr_t>(this) & HostCallFrameFlag; }

   150         CallFrame* addHostCallFrameFlag() const { return reinterpret_cast<CallFrame*>(reinterpret_cast<intptr_t>(this) | HostCallFrameFlag); }

   151         CallFrame* removeHostCallFrameFlag() { return reinterpret_cast<CallFrame*>(reinterpret_cast<intptr_t>(this) & ~HostCallFrameFlag); }

   152 

   153         void setArgumentCountIncludingThis(int count) { static_cast<Register*>(this)[RegisterFile::ArgumentCount] = Register::withInt(count); }

   154         void setCallee(JSObject* callee) { static_cast<Register*>(this)[RegisterFile::Callee] = Register::withCallee(callee); }

   155         void setCodeBlock(CodeBlock* codeBlock) { static_cast<Register*>(this)[RegisterFile::CodeBlock] = codeBlock; }

   156         void setReturnPC(void* value) { static_cast<Register*>(this)[RegisterFile::ReturnPC] = (Instruction*)value; }

   157 

   158     private:

   159         static const intptr_t HostCallFrameFlag = 1;

   160 #ifndef NDEBUG

   161         RegisterFile* registerFile();

   162 #endif

   163         ExecState();

   164         ~ExecState();

   165     };

   166 

   167 } // namespace JSC

   168 

   169 #endif // CallFrame_h