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      1 // Copyright 2012 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef V8_ARGUMENTS_H_
      6 #define V8_ARGUMENTS_H_
      7 
      8 #include "src/allocation.h"
      9 #include "src/isolate.h"
     10 
     11 namespace v8 {
     12 namespace internal {
     13 
     14 // Arguments provides access to runtime call parameters.
     15 //
     16 // It uses the fact that the instance fields of Arguments
     17 // (length_, arguments_) are "overlayed" with the parameters
     18 // (no. of parameters, and the parameter pointer) passed so
     19 // that inside the C++ function, the parameters passed can
     20 // be accessed conveniently:
     21 //
     22 //   Object* Runtime_function(Arguments args) {
     23 //     ... use args[i] here ...
     24 //   }
     25 //
     26 // Note that length_ (whose value is in the integer range) is defined
     27 // as intptr_t to provide endian-neutrality on 64-bit archs.
     28 
     29 class Arguments BASE_EMBEDDED {
     30  public:
     31   Arguments(int length, Object** arguments)
     32       : length_(length), arguments_(arguments) {
     33     DCHECK_GE(length_, 0);
     34   }
     35 
     36   Object*& operator[] (int index) {
     37     DCHECK_GE(index, 0);
     38     DCHECK_LT(static_cast<uint32_t>(index), static_cast<uint32_t>(length_));
     39     return *(reinterpret_cast<Object**>(reinterpret_cast<intptr_t>(arguments_) -
     40                                         index * kPointerSize));
     41   }
     42 
     43   template <class S> Handle<S> at(int index) {
     44     Object** value = &((*this)[index]);
     45     // This cast checks that the object we're accessing does indeed have the
     46     // expected type.
     47     S::cast(*value);
     48     return Handle<S>(reinterpret_cast<S**>(value));
     49   }
     50 
     51   int smi_at(int index) {
     52     return Smi::cast((*this)[index])->value();
     53   }
     54 
     55   double number_at(int index) {
     56     return (*this)[index]->Number();
     57   }
     58 
     59   // Get the total number of arguments including the receiver.
     60   int length() const { return static_cast<int>(length_); }
     61 
     62   Object** arguments() { return arguments_; }
     63 
     64   Object** lowest_address() { return &this->operator[](length() - 1); }
     65 
     66   Object** highest_address() { return &this->operator[](0); }
     67 
     68  private:
     69   intptr_t length_;
     70   Object** arguments_;
     71 };
     72 
     73 
     74 // For each type of callback, we have a list of arguments
     75 // They are used to generate the Call() functions below
     76 // These aren't included in the list as they have duplicate signatures
     77 // F(GenericNamedPropertyEnumeratorCallback, ...)
     78 // F(GenericNamedPropertyGetterCallback, ...)
     79 
     80 #define FOR_EACH_CALLBACK_TABLE_MAPPING_0(F) \
     81   F(IndexedPropertyEnumeratorCallback, v8::Array)
     82 
     83 #define FOR_EACH_CALLBACK_TABLE_MAPPING_1(F)                               \
     84   F(AccessorNameGetterCallback, v8::Value, v8::Local<v8::Name>)            \
     85   F(GenericNamedPropertyQueryCallback, v8::Integer, v8::Local<v8::Name>)   \
     86   F(GenericNamedPropertyDeleterCallback, v8::Boolean, v8::Local<v8::Name>) \
     87   F(IndexedPropertyGetterCallback, v8::Value, uint32_t)                    \
     88   F(IndexedPropertyQueryCallback, v8::Integer, uint32_t)                   \
     89   F(IndexedPropertyDeleterCallback, v8::Boolean, uint32_t)
     90 
     91 #define FOR_EACH_CALLBACK_TABLE_MAPPING_2(F)                            \
     92   F(GenericNamedPropertySetterCallback, v8::Value, v8::Local<v8::Name>, \
     93     v8::Local<v8::Value>)                                               \
     94   F(IndexedPropertySetterCallback, v8::Value, uint32_t, v8::Local<v8::Value>)
     95 
     96 #define FOR_EACH_CALLBACK_TABLE_MAPPING_2_VOID_RETURN(F) \
     97   F(AccessorNameSetterCallback, \
     98     void, \
     99     v8::Local<v8::Name>, \
    100     v8::Local<v8::Value>) \
    101 
    102 
    103 // Custom arguments replicate a small segment of stack that can be
    104 // accessed through an Arguments object the same way the actual stack
    105 // can.
    106 template<int kArrayLength>
    107 class CustomArgumentsBase : public Relocatable {
    108  public:
    109   virtual inline void IterateInstance(ObjectVisitor* v) {
    110     v->VisitPointers(values_, values_ + kArrayLength);
    111   }
    112  protected:
    113   inline Object** begin() { return values_; }
    114   explicit inline CustomArgumentsBase(Isolate* isolate)
    115       : Relocatable(isolate) {}
    116   Object* values_[kArrayLength];
    117 };
    118 
    119 
    120 template<typename T>
    121 class CustomArguments : public CustomArgumentsBase<T::kArgsLength> {
    122  public:
    123   static const int kReturnValueOffset = T::kReturnValueIndex;
    124 
    125   typedef CustomArgumentsBase<T::kArgsLength> Super;
    126   ~CustomArguments() {
    127     this->begin()[kReturnValueOffset] =
    128         reinterpret_cast<Object*>(kHandleZapValue);
    129   }
    130 
    131  protected:
    132   explicit inline CustomArguments(Isolate* isolate) : Super(isolate) {}
    133 
    134   template <typename V>
    135   v8::Local<V> GetReturnValue(Isolate* isolate);
    136 
    137   inline Isolate* isolate() {
    138     return reinterpret_cast<Isolate*>(this->begin()[T::kIsolateIndex]);
    139   }
    140 };
    141 
    142 
    143 class PropertyCallbackArguments
    144     : public CustomArguments<PropertyCallbackInfo<Value> > {
    145  public:
    146   typedef PropertyCallbackInfo<Value> T;
    147   typedef CustomArguments<T> Super;
    148   static const int kArgsLength = T::kArgsLength;
    149   static const int kThisIndex = T::kThisIndex;
    150   static const int kHolderIndex = T::kHolderIndex;
    151   static const int kDataIndex = T::kDataIndex;
    152   static const int kReturnValueDefaultValueIndex =
    153       T::kReturnValueDefaultValueIndex;
    154   static const int kIsolateIndex = T::kIsolateIndex;
    155 
    156   PropertyCallbackArguments(Isolate* isolate,
    157                             Object* data,
    158                             Object* self,
    159                             JSObject* holder)
    160       : Super(isolate) {
    161     Object** values = this->begin();
    162     values[T::kThisIndex] = self;
    163     values[T::kHolderIndex] = holder;
    164     values[T::kDataIndex] = data;
    165     values[T::kIsolateIndex] = reinterpret_cast<Object*>(isolate);
    166     // Here the hole is set as default value.
    167     // It cannot escape into js as it's remove in Call below.
    168     values[T::kReturnValueDefaultValueIndex] =
    169         isolate->heap()->the_hole_value();
    170     values[T::kReturnValueIndex] = isolate->heap()->the_hole_value();
    171     DCHECK(values[T::kHolderIndex]->IsHeapObject());
    172     DCHECK(values[T::kIsolateIndex]->IsSmi());
    173   }
    174 
    175   /*
    176    * The following Call functions wrap the calling of all callbacks to handle
    177    * calling either the old or the new style callbacks depending on which one
    178    * has been registered.
    179    * For old callbacks which return an empty handle, the ReturnValue is checked
    180    * and used if it's been set to anything inside the callback.
    181    * New style callbacks always use the return value.
    182    */
    183 #define WRITE_CALL_0(Function, ReturnValue) \
    184   v8::Local<ReturnValue> Call(Function f);
    185 
    186 #define WRITE_CALL_1(Function, ReturnValue, Arg1) \
    187   v8::Local<ReturnValue> Call(Function f, Arg1 arg1);
    188 
    189 #define WRITE_CALL_2(Function, ReturnValue, Arg1, Arg2) \
    190   v8::Local<ReturnValue> Call(Function f, Arg1 arg1, Arg2 arg2);
    191 
    192 #define WRITE_CALL_2_VOID(Function, ReturnValue, Arg1, Arg2)                 \
    193   void Call(Function f, Arg1 arg1, Arg2 arg2);                               \
    194 
    195 FOR_EACH_CALLBACK_TABLE_MAPPING_0(WRITE_CALL_0)
    196 FOR_EACH_CALLBACK_TABLE_MAPPING_1(WRITE_CALL_1)
    197 FOR_EACH_CALLBACK_TABLE_MAPPING_2(WRITE_CALL_2)
    198 FOR_EACH_CALLBACK_TABLE_MAPPING_2_VOID_RETURN(WRITE_CALL_2_VOID)
    199 
    200 #undef WRITE_CALL_0
    201 #undef WRITE_CALL_1
    202 #undef WRITE_CALL_2
    203 #undef WRITE_CALL_2_VOID
    204 };
    205 
    206 
    207 class FunctionCallbackArguments
    208     : public CustomArguments<FunctionCallbackInfo<Value> > {
    209  public:
    210   typedef FunctionCallbackInfo<Value> T;
    211   typedef CustomArguments<T> Super;
    212   static const int kArgsLength = T::kArgsLength;
    213   static const int kHolderIndex = T::kHolderIndex;
    214   static const int kDataIndex = T::kDataIndex;
    215   static const int kReturnValueDefaultValueIndex =
    216       T::kReturnValueDefaultValueIndex;
    217   static const int kIsolateIndex = T::kIsolateIndex;
    218   static const int kCalleeIndex = T::kCalleeIndex;
    219   static const int kContextSaveIndex = T::kContextSaveIndex;
    220 
    221   FunctionCallbackArguments(internal::Isolate* isolate,
    222       internal::Object* data,
    223       internal::JSFunction* callee,
    224       internal::Object* holder,
    225       internal::Object** argv,
    226       int argc,
    227       bool is_construct_call)
    228         : Super(isolate),
    229           argv_(argv),
    230           argc_(argc),
    231           is_construct_call_(is_construct_call) {
    232     Object** values = begin();
    233     values[T::kDataIndex] = data;
    234     values[T::kCalleeIndex] = callee;
    235     values[T::kHolderIndex] = holder;
    236     values[T::kContextSaveIndex] = isolate->heap()->the_hole_value();
    237     values[T::kIsolateIndex] = reinterpret_cast<internal::Object*>(isolate);
    238     // Here the hole is set as default value.
    239     // It cannot escape into js as it's remove in Call below.
    240     values[T::kReturnValueDefaultValueIndex] =
    241         isolate->heap()->the_hole_value();
    242     values[T::kReturnValueIndex] = isolate->heap()->the_hole_value();
    243     DCHECK(values[T::kCalleeIndex]->IsJSFunction());
    244     DCHECK(values[T::kHolderIndex]->IsHeapObject());
    245     DCHECK(values[T::kIsolateIndex]->IsSmi());
    246   }
    247 
    248   /*
    249    * The following Call function wraps the calling of all callbacks to handle
    250    * calling either the old or the new style callbacks depending on which one
    251    * has been registered.
    252    * For old callbacks which return an empty handle, the ReturnValue is checked
    253    * and used if it's been set to anything inside the callback.
    254    * New style callbacks always use the return value.
    255    */
    256   v8::Local<v8::Value> Call(FunctionCallback f);
    257 
    258  private:
    259   internal::Object** argv_;
    260   int argc_;
    261   bool is_construct_call_;
    262 };
    263 
    264 
    265 double ClobberDoubleRegisters(double x1, double x2, double x3, double x4);
    266 
    267 
    268 #ifdef DEBUG
    269 #define CLOBBER_DOUBLE_REGISTERS() ClobberDoubleRegisters(1, 2, 3, 4);
    270 #else
    271 #define CLOBBER_DOUBLE_REGISTERS()
    272 #endif
    273 
    274 
    275 #define RUNTIME_FUNCTION_RETURNS_TYPE(Type, Name)                        \
    276 static INLINE(Type __RT_impl_##Name(Arguments args, Isolate* isolate));  \
    277 Type Name(int args_length, Object** args_object, Isolate* isolate) {     \
    278   CLOBBER_DOUBLE_REGISTERS();                                            \
    279   Arguments args(args_length, args_object);                              \
    280   return __RT_impl_##Name(args, isolate);                                \
    281 }                                                                        \
    282 static Type __RT_impl_##Name(Arguments args, Isolate* isolate)
    283 
    284 
    285 #define RUNTIME_FUNCTION(Name) RUNTIME_FUNCTION_RETURNS_TYPE(Object*, Name)
    286 #define RUNTIME_FUNCTION_RETURN_PAIR(Name) \
    287     RUNTIME_FUNCTION_RETURNS_TYPE(ObjectPair, Name)
    288 
    289 }  // namespace internal
    290 }  // namespace v8
    291 
    292 #endif  // V8_ARGUMENTS_H_
    293