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, 2013, 2014 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#include "StackVisitor.h"
32
33namespace JSC  {
34
35    class Arguments;
36    class JSActivation;
37    class Interpreter;
38    class JSScope;
39
40    // Represents the current state of script execution.
41    // Passed as the first argument to most functions.
42    class ExecState : private Register {
43    public:
44        JSValue calleeAsValue() const { return this[JSStack::Callee].jsValue(); }
45        JSObject* callee() const { return this[JSStack::Callee].function(); }
46        CodeBlock* codeBlock() const { return this[JSStack::CodeBlock].Register::codeBlock(); }
47        JSScope* scope() const
48        {
49            ASSERT(this[JSStack::ScopeChain].Register::scope());
50            return this[JSStack::ScopeChain].Register::scope();
51        }
52
53        bool hasActivation() const { return !!uncheckedActivation(); }
54        JSActivation* activation() const;
55        JSValue uncheckedActivation() const;
56
57        // Global object in which execution began.
58        JS_EXPORT_PRIVATE JSGlobalObject* vmEntryGlobalObject();
59
60        // Global object in which the currently executing code was defined.
61        // Differs from vmEntryGlobalObject() during function calls across web browser frames.
62        JSGlobalObject* lexicalGlobalObject() const;
63
64        // Differs from lexicalGlobalObject because this will have DOM window shell rather than
65        // the actual DOM window, which can't be "this" for security reasons.
66        JSObject* globalThisValue() const;
67
68        VM& vm() const;
69
70        // Convenience functions for access to global data.
71        // It takes a few memory references to get from a call frame to the global data
72        // pointer, so these are inefficient, and should be used sparingly in new code.
73        // But they're used in many places in legacy code, so they're not going away any time soon.
74
75        void clearException() { vm().clearException(); }
76        void clearSupplementaryExceptionInfo()
77        {
78            vm().clearExceptionStack();
79        }
80
81        JSValue exception() const { return vm().exception(); }
82        bool hadException() const { return !vm().exception().isEmpty(); }
83
84        AtomicStringTable* atomicStringTable() const { return vm().atomicStringTable(); }
85        const CommonIdentifiers& propertyNames() const { return *vm().propertyNames; }
86        const MarkedArgumentBuffer& emptyList() const { return *vm().emptyList; }
87        Interpreter* interpreter() { return vm().interpreter; }
88        Heap* heap() { return &vm().heap; }
89
90        static const HashTable& arrayConstructorTable(VM& vm) { return *vm.arrayConstructorTable; }
91        static const HashTable& arrayPrototypeTable(VM& vm) { return *vm.arrayPrototypeTable; }
92        static const HashTable& booleanPrototypeTable(VM& vm) { return *vm.booleanPrototypeTable; }
93        static const HashTable& dataViewTable(VM& vm) { return *vm.dataViewTable; }
94        static const HashTable& dateTable(VM& vm) { return *vm.dateTable; }
95        static const HashTable& dateConstructorTable(VM& vm) { return *vm.dateConstructorTable; }
96        static const HashTable& errorPrototypeTable(VM& vm) { return *vm.errorPrototypeTable; }
97        static const HashTable& globalObjectTable(VM& vm) { return *vm.globalObjectTable; }
98        static const HashTable& jsonTable(VM& vm) { return *vm.jsonTable; }
99        static const HashTable& numberConstructorTable(VM& vm) { return *vm.numberConstructorTable; }
100        static const HashTable& numberPrototypeTable(VM& vm) { return *vm.numberPrototypeTable; }
101        static const HashTable& objectConstructorTable(VM& vm) { return *vm.objectConstructorTable; }
102        static const HashTable& privateNamePrototypeTable(VM& vm) { return *vm.privateNamePrototypeTable; }
103        static const HashTable& regExpTable(VM& vm) { return *vm.regExpTable; }
104        static const HashTable& regExpConstructorTable(VM& vm) { return *vm.regExpConstructorTable; }
105        static const HashTable& regExpPrototypeTable(VM& vm) { return *vm.regExpPrototypeTable; }
106        static const HashTable& stringConstructorTable(VM& vm) { return *vm.stringConstructorTable; }
107#if ENABLE(PROMISES)
108        static const HashTable& promisePrototypeTable(VM& vm) { return *vm.promisePrototypeTable; }
109        static const HashTable& promiseConstructorTable(VM& vm) { return *vm.promiseConstructorTable; }
110#endif
111
112        static CallFrame* create(Register* callFrameBase) { return static_cast<CallFrame*>(callFrameBase); }
113        Register* registers() { return this; }
114        const Register* registers() const { return this; }
115
116        CallFrame& operator=(const Register& r) { *static_cast<Register*>(this) = r; return *this; }
117
118        CallFrame* callerFrame() const { return callerFrameAndPC().callerFrame; }
119        static ptrdiff_t callerFrameOffset() { return OBJECT_OFFSETOF(CallerFrameAndPC, callerFrame); }
120
121        ReturnAddressPtr returnPC() const { return ReturnAddressPtr(callerFrameAndPC().pc); }
122        bool hasReturnPC() const { return !!callerFrameAndPC().pc; }
123        void clearReturnPC() { callerFrameAndPC().pc = 0; }
124        static ptrdiff_t returnPCOffset() { return OBJECT_OFFSETOF(CallerFrameAndPC, pc); }
125        AbstractPC abstractReturnPC(VM& vm) { return AbstractPC(vm, this); }
126
127        class Location {
128        public:
129            static inline uint32_t decode(uint32_t bits);
130
131            static inline bool isBytecodeLocation(uint32_t bits);
132#if USE(JSVALUE64)
133            static inline uint32_t encodeAsBytecodeOffset(uint32_t bits);
134#else
135            static inline uint32_t encodeAsBytecodeInstruction(Instruction*);
136#endif
137
138            static inline bool isCodeOriginIndex(uint32_t bits);
139            static inline uint32_t encodeAsCodeOriginIndex(uint32_t bits);
140
141        private:
142            enum TypeTag {
143                BytecodeLocationTag = 0,
144                CodeOriginIndexTag = 1,
145            };
146
147            static inline uint32_t encode(TypeTag, uint32_t bits);
148
149            static const uint32_t s_mask = 0x1;
150#if USE(JSVALUE64)
151            static const uint32_t s_shift = 31;
152            static const uint32_t s_shiftedMask = s_mask << s_shift;
153#else
154            static const uint32_t s_shift = 1;
155#endif
156        };
157
158        bool hasLocationAsBytecodeOffset() const;
159        bool hasLocationAsCodeOriginIndex() const;
160
161        unsigned locationAsRawBits() const;
162        unsigned locationAsBytecodeOffset() const;
163        unsigned locationAsCodeOriginIndex() const;
164
165        void setLocationAsRawBits(unsigned);
166        void setLocationAsBytecodeOffset(unsigned);
167
168#if ENABLE(DFG_JIT)
169        unsigned bytecodeOffsetFromCodeOriginIndex();
170#endif
171
172        // This will try to get you the bytecode offset, but you should be aware that
173        // this bytecode offset may be bogus in the presence of inlining. This will
174        // also return 0 if the call frame has no notion of bytecode offsets (for
175        // example if it's native code).
176        // https://bugs.webkit.org/show_bug.cgi?id=121754
177        unsigned bytecodeOffset();
178
179        // This will get you a CodeOrigin. It will always succeed. May return
180        // CodeOrigin(0) if we're in native code.
181        CodeOrigin codeOrigin();
182
183        Register* topOfFrame()
184        {
185            if (isVMEntrySentinel() || !codeBlock())
186                return registers();
187            return topOfFrameInternal();
188        }
189
190#if USE(JSVALUE32_64)
191        Instruction* currentVPC() const
192        {
193            ASSERT(!isVMEntrySentinel());
194            return bitwise_cast<Instruction*>(this[JSStack::ArgumentCount].tag());
195        }
196        void setCurrentVPC(Instruction* vpc)
197        {
198            ASSERT(!isVMEntrySentinel());
199            this[JSStack::ArgumentCount].tag() = bitwise_cast<int32_t>(vpc);
200        }
201#else
202        Instruction* currentVPC() const;
203        void setCurrentVPC(Instruction* vpc);
204#endif
205
206        void setCallerFrame(CallFrame* frame) { callerFrameAndPC().callerFrame = frame; }
207        void setScope(JSScope* scope) { static_cast<Register*>(this)[JSStack::ScopeChain] = scope; }
208        void setActivation(JSActivation*);
209
210        ALWAYS_INLINE void init(CodeBlock* codeBlock, Instruction* vPC, JSScope* scope,
211            CallFrame* callerFrame, int argc, JSObject* callee)
212        {
213            ASSERT(callerFrame == noCaller() || callerFrame->isVMEntrySentinel() || callerFrame->stack()->containsAddress(this));
214
215            setCodeBlock(codeBlock);
216            setScope(scope);
217            setCallerFrame(callerFrame);
218            setReturnPC(vPC); // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*.
219            setArgumentCountIncludingThis(argc); // original argument count (for the sake of the "arguments" object)
220            setCallee(callee);
221        }
222
223        // Read a register from the codeframe (or constant from the CodeBlock).
224        Register& r(int);
225        // Read a register for a non-constant
226        Register& uncheckedR(int);
227
228        // Access to arguments as passed. (After capture, arguments may move to a different location.)
229        size_t argumentCount() const { return argumentCountIncludingThis() - 1; }
230        size_t argumentCountIncludingThis() const { return this[JSStack::ArgumentCount].payload(); }
231        static int argumentOffset(int argument) { return (JSStack::FirstArgument + argument); }
232        static int argumentOffsetIncludingThis(int argument) { return (JSStack::ThisArgument + argument); }
233
234        // In the following (argument() and setArgument()), the 'argument'
235        // parameter is the index of the arguments of the target function of
236        // this frame. The index starts at 0 for the first arg, 1 for the
237        // second, etc.
238        //
239        // The arguments (in this case) do not include the 'this' value.
240        // arguments(0) will not fetch the 'this' value. To get/set 'this',
241        // use thisValue() and setThisValue() below.
242
243        JSValue argument(size_t argument)
244        {
245            if (argument >= argumentCount())
246                 return jsUndefined();
247            return getArgumentUnsafe(argument);
248        }
249        JSValue uncheckedArgument(size_t argument)
250        {
251            ASSERT(argument < argumentCount());
252            return getArgumentUnsafe(argument);
253        }
254        void setArgument(size_t argument, JSValue value)
255        {
256            this[argumentOffset(argument)] = value;
257        }
258
259        static int thisArgumentOffset() { return argumentOffsetIncludingThis(0); }
260        JSValue thisValue() { return this[thisArgumentOffset()].jsValue(); }
261        void setThisValue(JSValue value) { this[thisArgumentOffset()] = value; }
262
263        JSValue argumentAfterCapture(size_t argument);
264
265        static int offsetFor(size_t argumentCountIncludingThis) { return argumentCountIncludingThis + JSStack::ThisArgument - 1; }
266
267        static CallFrame* noCaller() { return 0; }
268
269        bool isVMEntrySentinel() const
270        {
271            return !!this && codeBlock() == vmEntrySentinelCodeBlock();
272        }
273
274        CallFrame* vmEntrySentinelCallerFrame() const
275        {
276            ASSERT(isVMEntrySentinel());
277            return this[JSStack::ScopeChain].callFrame();
278        }
279
280        void initializeVMEntrySentinelFrame(CallFrame* callFrame)
281        {
282            setCallerFrame(noCaller());
283            setReturnPC(0);
284            setCodeBlock(vmEntrySentinelCodeBlock());
285            static_cast<Register*>(this)[JSStack::ScopeChain] = callFrame;
286            setCallee(0);
287            setArgumentCountIncludingThis(0);
288        }
289
290        CallFrame* callerFrameSkippingVMEntrySentinel()
291        {
292            CallFrame* caller = callerFrame();
293            if (caller->isVMEntrySentinel())
294                return caller->vmEntrySentinelCallerFrame();
295            return caller;
296        }
297
298        void setArgumentCountIncludingThis(int count) { static_cast<Register*>(this)[JSStack::ArgumentCount].payload() = count; }
299        void setCallee(JSObject* callee) { static_cast<Register*>(this)[JSStack::Callee] = Register::withCallee(callee); }
300        void setCodeBlock(CodeBlock* codeBlock) { static_cast<Register*>(this)[JSStack::CodeBlock] = codeBlock; }
301        void setReturnPC(void* value) { callerFrameAndPC().pc = reinterpret_cast<Instruction*>(value); }
302
303        // CallFrame::iterate() expects a Functor that implements the following method:
304        //     StackVisitor::Status operator()(StackVisitor&);
305
306        template <typename Functor> void iterate(Functor& functor)
307        {
308            StackVisitor::visit<Functor>(this, functor);
309        }
310
311        void dump(PrintStream&);
312        JS_EXPORT_PRIVATE const char* describeFrame();
313
314    private:
315        static const intptr_t s_VMEntrySentinel = 1;
316
317#ifndef NDEBUG
318        JSStack* stack();
319#endif
320        ExecState();
321        ~ExecState();
322
323        Register* topOfFrameInternal();
324
325        // The following are for internal use in debugging and verification
326        // code only and not meant as an API for general usage:
327
328        size_t argIndexForRegister(Register* reg)
329        {
330            // The register at 'offset' number of slots from the frame pointer
331            // i.e.
332            //       reg = frame[offset];
333            //   ==> reg = frame + offset;
334            //   ==> offset = reg - frame;
335            int offset = reg - this->registers();
336
337            // The offset is defined (based on argumentOffset()) to be:
338            //       offset = JSStack::FirstArgument - argIndex;
339            // Hence:
340            //       argIndex = JSStack::FirstArgument - offset;
341            size_t argIndex = offset - JSStack::FirstArgument;
342            return argIndex;
343        }
344
345        JSValue getArgumentUnsafe(size_t argIndex)
346        {
347            // User beware! This method does not verify that there is a valid
348            // argument at the specified argIndex. This is used for debugging
349            // and verification code only. The caller is expected to know what
350            // he/she is doing when calling this method.
351            return this[argumentOffset(argIndex)].jsValue();
352        }
353
354        CallerFrameAndPC& callerFrameAndPC() { return *reinterpret_cast<CallerFrameAndPC*>(this); }
355        const CallerFrameAndPC& callerFrameAndPC() const { return *reinterpret_cast<const CallerFrameAndPC*>(this); }
356
357        static CodeBlock* vmEntrySentinelCodeBlock() { return reinterpret_cast<CodeBlock*>(s_VMEntrySentinel); }
358
359        friend class JSStack;
360        friend class VMInspector;
361    };
362
363} // namespace JSC
364
365#endif // CallFrame_h
366