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, 2011 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 "AbstractPC.h"
  27 #include "VM.h"
  28 #include "JSStack.h"
  29 #include "MacroAssemblerCodeRef.h"
  30 #include "Register.h"
  31
  32 namespace JSC  {
  33
  34     class Arguments;
  35     class JSActivation;
  36     class Interpreter;
  37     class JSScope;
  38
  39     // Represents the current state of script execution.
  40     // Passed as the first argument to most functions.
  41     class ExecState : private Register {
  42     public:
  43         JSValue calleeAsValue() const { return this[JSStack::Callee].jsValue(); }
  44         JSObject* callee() const { return this[JSStack::Callee].function(); }
  45         CodeBlock* codeBlock() const { return this[JSStack::CodeBlock].Register::codeBlock(); }
  46         JSScope* scope() const
  47         {
  48             ASSERT(this[JSStack::ScopeChain].Register::scope());
  49             return this[JSStack::ScopeChain].Register::scope();
  50         }
  51
  52         // Global object in which execution began.
  53         JSGlobalObject* dynamicGlobalObject();
  54
  55         // Global object in which the currently executing code was defined.
  56         // Differs from dynamicGlobalObject() during function calls across web browser frames.
  57         JSGlobalObject* lexicalGlobalObject() const;
  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         VM& vm() const;
  64
  65         // Convenience functions for access to global data.
  66         // It takes a few memory references to get from a call frame to the global data
  67         // pointer, so these are inefficient, and should be used sparingly in new code.
  68         // But they're used in many places in legacy code, so they're not going away any time soon.
  69
  70         void clearException() { vm().exception = JSValue(); }
  71         void clearSupplementaryExceptionInfo()
  72         {
  73             vm().clearExceptionStack();
  74         }
  75
  76         JSValue exception() const { return vm().exception; }
  77         bool hadException() const { return vm().exception; }
  78
  79         const CommonIdentifiers& propertyNames() const { return *vm().propertyNames; }
  80         const MarkedArgumentBuffer& emptyList() const { return *vm().emptyList; }
  81         Interpreter* interpreter() { return vm().interpreter; }
  82         Heap* heap() { return &vm().heap; }
  83 #ifndef NDEBUG
  84         void dumpCaller();
  85 #endif
  86         static const HashTable* arrayConstructorTable(CallFrame* callFrame) { return callFrame->vm().arrayConstructorTable; }
  87         static const HashTable* arrayPrototypeTable(CallFrame* callFrame) { return callFrame->vm().arrayPrototypeTable; }
  88         static const HashTable* booleanPrototypeTable(CallFrame* callFrame) { return callFrame->vm().booleanPrototypeTable; }
  89         static const HashTable* dateTable(CallFrame* callFrame) { return callFrame->vm().dateTable; }
  90         static const HashTable* dateConstructorTable(CallFrame* callFrame) { return callFrame->vm().dateConstructorTable; }
  91         static const HashTable* errorPrototypeTable(CallFrame* callFrame) { return callFrame->vm().errorPrototypeTable; }
  92         static const HashTable* globalObjectTable(CallFrame* callFrame) { return callFrame->vm().globalObjectTable; }
  93         static const HashTable* jsonTable(CallFrame* callFrame) { return callFrame->vm().jsonTable; }
  94         static const HashTable* mathTable(CallFrame* callFrame) { return callFrame->vm().mathTable; }
  95         static const HashTable* numberConstructorTable(CallFrame* callFrame) { return callFrame->vm().numberConstructorTable; }
  96         static const HashTable* numberPrototypeTable(CallFrame* callFrame) { return callFrame->vm().numberPrototypeTable; }
  97         static const HashTable* objectConstructorTable(CallFrame* callFrame) { return callFrame->vm().objectConstructorTable; }
  98         static const HashTable* privateNamePrototypeTable(CallFrame* callFrame) { return callFrame->vm().privateNamePrototypeTable; }
  99         static const HashTable* regExpTable(CallFrame* callFrame) { return callFrame->vm().regExpTable; }
 100         static const HashTable* regExpConstructorTable(CallFrame* callFrame) { return callFrame->vm().regExpConstructorTable; }
 101         static const HashTable* regExpPrototypeTable(CallFrame* callFrame) { return callFrame->vm().regExpPrototypeTable; }
 102         static const HashTable* stringConstructorTable(CallFrame* callFrame) { return callFrame->vm().stringConstructorTable; }
 103
 104         static CallFrame* create(Register* callFrameBase) { return static_cast<CallFrame*>(callFrameBase); }
 105         Register* registers() { return this; }
 106
 107         CallFrame& operator=(const Register& r) { *static_cast<Register*>(this) = r; return *this; }
 108
 109         CallFrame* callerFrame() const { return this[JSStack::CallerFrame].callFrame(); }
 110 #if ENABLE(JIT) || ENABLE(LLINT)
 111         ReturnAddressPtr returnPC() const { return ReturnAddressPtr(this[JSStack::ReturnPC].vPC()); }
 112         bool hasReturnPC() const { return !!this[JSStack::ReturnPC].vPC(); }
 113         void clearReturnPC() { registers()[JSStack::ReturnPC] = static_cast<Instruction*>(0); }
 114 #endif
 115         AbstractPC abstractReturnPC(VM& vm) { return AbstractPC(vm, this); }
 116 #if USE(JSVALUE32_64)
 117         unsigned bytecodeOffsetForNonDFGCode() const;
 118         void setBytecodeOffsetForNonDFGCode(unsigned offset);
 119 #else
 120         unsigned bytecodeOffsetForNonDFGCode() const
 121         {
 122             ASSERT(codeBlock());
 123             return this[JSStack::ArgumentCount].tag();
 124         }
 125
 126         void setBytecodeOffsetForNonDFGCode(unsigned offset)
 127         {
 128             ASSERT(codeBlock());
 129             this[JSStack::ArgumentCount].tag() = static_cast<int32_t>(offset);
 130         }
 131 #endif
 132
 133         Register* frameExtent()
 134         {
 135             if (!codeBlock())
 136                 return registers();
 137             return frameExtentInternal();
 138         }
 139
 140         Register* frameExtentInternal();
 141
 142 #if ENABLE(DFG_JIT)
 143         InlineCallFrame* inlineCallFrame() const { return this[JSStack::ReturnPC].asInlineCallFrame(); }
 144         unsigned codeOriginIndexForDFG() const { return this[JSStack::ArgumentCount].tag(); }
 145 #else
 146         // This will never be called if !ENABLE(DFG_JIT) since all calls should be guarded by
 147         // isInlineCallFrame(). But to make it easier to write code without having a bunch of
 148         // #if's, we make a dummy implementation available anyway.
 149         InlineCallFrame* inlineCallFrame() const
 150         {
 151             RELEASE_ASSERT_NOT_REACHED();
 152             return 0;
 153         }
 154 #endif
 155 #if USE(JSVALUE32_64)
 156         Instruction* currentVPC() const
 157         {
 158             return bitwise_cast<Instruction*>(this[JSStack::ArgumentCount].tag());
 159         }
 160         void setCurrentVPC(Instruction* vpc)
 161         {
 162             this[JSStack::ArgumentCount].tag() = bitwise_cast<int32_t>(vpc);
 163         }
 164 #else
 165         Instruction* currentVPC() const;
 166         void setCurrentVPC(Instruction* vpc);
 167 #endif
 168
 169         void setCallerFrame(CallFrame* callerFrame) { static_cast<Register*>(this)[JSStack::CallerFrame] = callerFrame; }
 170         void setScope(JSScope* scope) { static_cast<Register*>(this)[JSStack::ScopeChain] = scope; }
 171
 172         ALWAYS_INLINE void init(CodeBlock* codeBlock, Instruction* vPC, JSScope* scope,
 173             CallFrame* callerFrame, int argc, JSObject* callee)
 174         {
 175             ASSERT(callerFrame); // Use noCaller() rather than 0 for the outer host call frame caller.
 176             ASSERT(callerFrame == noCaller() || callerFrame->removeHostCallFrameFlag()->stack()->end() >= this);
 177
 178             setCodeBlock(codeBlock);
 179             setScope(scope);
 180             setCallerFrame(callerFrame);
 181             setReturnPC(vPC); // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*.
 182             setArgumentCountIncludingThis(argc); // original argument count (for the sake of the "arguments" object)
 183             setCallee(callee);
 184         }
 185
 186         // Read a register from the codeframe (or constant from the CodeBlock).
 187         Register& r(int);
 188         // Read a register for a non-constant
 189         Register& uncheckedR(int);
 190
 191         // Access to arguments as passed. (After capture, arguments may move to a different location.)
 192         size_t argumentCount() const { return argumentCountIncludingThis() - 1; }
 193         size_t argumentCountIncludingThis() const { return this[JSStack::ArgumentCount].payload(); }
 194         static int argumentOffset(int argument) { return s_firstArgumentOffset - argument; }
 195         static int argumentOffsetIncludingThis(int argument) { return s_thisArgumentOffset - argument; }
 196
 197         // In the following (argument() and setArgument()), the 'argument'
 198         // parameter is the index of the arguments of the target function of
 199         // this frame. The index starts at 0 for the first arg, 1 for the
 200         // second, etc.
 201         //
 202         // The arguments (in this case) do not include the 'this' value.
 203         // arguments(0) will not fetch the 'this' value. To get/set 'this',
 204         // use thisValue() and setThisValue() below.
 205
 206         JSValue argument(size_t argument)
 207         {
 208             if (argument >= argumentCount())
 209                  return jsUndefined();
 210             return this[argumentOffset(argument)].jsValue();
 211         }
 212         void setArgument(size_t argument, JSValue value)
 213         {
 214             this[argumentOffset(argument)] = value;
 215         }
 216
 217         static int thisArgumentOffset() { return argumentOffsetIncludingThis(0); }
 218         JSValue thisValue() { return this[thisArgumentOffset()].jsValue(); }
 219         void setThisValue(JSValue value) { this[thisArgumentOffset()] = value; }
 220
 221         JSValue argumentAfterCapture(size_t argument);
 222
 223         static int offsetFor(size_t argumentCountIncludingThis) { return argumentCountIncludingThis + JSStack::CallFrameHeaderSize; }
 224
 225         // FIXME: Remove these.
 226         int hostThisRegister() { return thisArgumentOffset(); }
 227         JSValue hostThisValue() { return thisValue(); }
 228
 229         static CallFrame* noCaller() { return reinterpret_cast<CallFrame*>(HostCallFrameFlag); }
 230
 231         bool hasHostCallFrameFlag() const { return reinterpret_cast<intptr_t>(this) & HostCallFrameFlag; }
 232         CallFrame* addHostCallFrameFlag() const { return reinterpret_cast<CallFrame*>(reinterpret_cast<intptr_t>(this) | HostCallFrameFlag); }
 233         CallFrame* removeHostCallFrameFlag() { return reinterpret_cast<CallFrame*>(reinterpret_cast<intptr_t>(this) & ~HostCallFrameFlag); }
 234
 235         void setArgumentCountIncludingThis(int count) { static_cast<Register*>(this)[JSStack::ArgumentCount].payload() = count; }
 236         void setCallee(JSObject* callee) { static_cast<Register*>(this)[JSStack::Callee] = Register::withCallee(callee); }
 237         void setCodeBlock(CodeBlock* codeBlock) { static_cast<Register*>(this)[JSStack::CodeBlock] = codeBlock; }
 238         void setReturnPC(void* value) { static_cast<Register*>(this)[JSStack::ReturnPC] = (Instruction*)value; }
 239
 240 #if ENABLE(DFG_JIT)
 241         bool isInlineCallFrame();
 242
 243         void setInlineCallFrame(InlineCallFrame* inlineCallFrame) { static_cast<Register*>(this)[JSStack::ReturnPC] = inlineCallFrame; }
 244
 245         // Call this to get the semantically correct JS CallFrame* for the
 246         // currently executing function.
 247         CallFrame* trueCallFrame(AbstractPC);
 248
 249         // Call this to get the semantically correct JS CallFrame* corresponding
 250         // to the caller. This resolves issues surrounding inlining and the
 251         // HostCallFrameFlag stuff.
 252         CallFrame* trueCallerFrame();
 253
 254         CodeBlock* someCodeBlockForPossiblyInlinedCode();
 255 #else
 256         bool isInlineCallFrame() { return false; }
 257
 258         CallFrame* trueCallFrame(AbstractPC) { return this; }
 259         CallFrame* trueCallerFrame() { return callerFrame()->removeHostCallFrameFlag(); }
 260
 261         CodeBlock* someCodeBlockForPossiblyInlinedCode() { return codeBlock(); }
 262 #endif
 263         CallFrame* callerFrameNoFlags() { return callerFrame()->removeHostCallFrameFlag(); }
 264
 265         // Call this to get the true call frame (accounted for inlining and any
 266         // other optimizations), when you have entered into VM code through one
 267         // of the "blessed" entrypoints (JITStubs or DFGOperations). This means
 268         // that if you're pretty much anywhere in the VM you can safely call this;
 269         // though if you were to magically get an ExecState* by, say, interrupting
 270         // a thread that is running JS code and brutishly scraped the call frame
 271         // register, calling this method would probably lead to horrible things
 272         // happening.
 273         CallFrame* trueCallFrameFromVMCode() { return trueCallFrame(AbstractPC()); }
 274
 275     private:
 276         static const intptr_t HostCallFrameFlag = 1;
 277         static const int s_thisArgumentOffset = -1 - JSStack::CallFrameHeaderSize;
 278         static const int s_firstArgumentOffset = s_thisArgumentOffset - 1;
 279
 280 #ifndef NDEBUG
 281         JSStack* stack();
 282 #endif
 283 #if ENABLE(DFG_JIT)
 284         bool isInlineCallFrameSlow();
 285 #endif
 286         ExecState();
 287         ~ExecState();
 288
 289         // The following are for internal use in debugging and verification
 290         // code only and not meant as an API for general usage:
 291
 292         size_t argIndexForRegister(Register* reg)
 293         {
 294             // The register at 'offset' number of slots from the frame pointer
 295             // i.e.
 296             //       reg = frame[offset];
 297             //   ==> reg = frame + offset;
 298             //   ==> offset = reg - frame;
 299             int offset = reg - this->registers();
 300
 301             // The offset is defined (based on argumentOffset()) to be:
 302             //       offset = s_firstArgumentOffset - argIndex;
 303             // Hence:
 304             //       argIndex = s_firstArgumentOffset - offset;
 305             size_t argIndex = s_firstArgumentOffset - offset;
 306             return argIndex;
 307         }
 308
 309         JSValue getArgumentUnsafe(size_t argIndex)
 310         {
 311             // User beware! This method does not verify that there is a valid
 312             // argument at the specified argIndex. This is used for debugging
 313             // and verification code only. The caller is expected to know what
 314             // he/she is doing when calling this method.
 315             return this[argumentOffset(argIndex)].jsValue();
 316         }
 317
 318         friend class JSStack;
 319         friend class VMInspector;
 320     };
 321
 322 } // namespace JSC
 323
 324 #endif // CallFrame_h