// Copyright 2017 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #ifndef V8_OBJECTS_ARGUMENTS_H_ #define V8_OBJECTS_ARGUMENTS_H_ #include "src/objects.h" // Has to be the last include (doesn't have include guards): #include "src/objects/object-macros.h" namespace v8 { namespace internal { // Common superclass for JSSloppyArgumentsObject and JSStrictArgumentsObject. // Note that the instance type {JS_ARGUMENTS_TYPE} does _not_ guarantee the // below layout, the in-object properties might have transitioned to dictionary // mode already. Only use the below layout with the specific initial maps. class JSArgumentsObject : public JSObject { public: // Offsets of object fields. static const int kLengthOffset = JSObject::kHeaderSize; static const int kSize = kLengthOffset + kPointerSize; // Indices of in-object properties. static const int kLengthIndex = 0; DECL_VERIFIER(JSArgumentsObject) DECL_CAST(JSArgumentsObject) private: DISALLOW_IMPLICIT_CONSTRUCTORS(JSArgumentsObject); }; // JSSloppyArgumentsObject is just a JSObject with specific initial map. // This initial map adds in-object properties for "length" and "callee". class JSSloppyArgumentsObject : public JSArgumentsObject { public: // Offsets of object fields. static const int kCalleeOffset = JSArgumentsObject::kSize; static const int kSize = kCalleeOffset + kPointerSize; // Indices of in-object properties. static const int kCalleeIndex = kLengthIndex + 1; inline static bool GetSloppyArgumentsLength(Isolate* isolate, Handle<JSObject> object, int* out); private: DISALLOW_IMPLICIT_CONSTRUCTORS(JSSloppyArgumentsObject); }; // JSStrictArgumentsObject is just a JSObject with specific initial map. // This initial map adds an in-object property for "length". class JSStrictArgumentsObject : public JSArgumentsObject { public: // Offsets of object fields. static const int kSize = JSArgumentsObject::kSize; private: DISALLOW_IMPLICIT_CONSTRUCTORS(JSStrictArgumentsObject); }; // Helper class to access FAST_ and SLOW_SLOPPY_ARGUMENTS_ELEMENTS // // +---+-----------------------+ // | 0 | Context* context | // +---------------------------+ // | 1 | FixedArray* arguments +----+ HOLEY_ELEMENTS // +---------------------------+ v-----+-----------+ // | 2 | Object* param_1_map | | 0 | the_hole | // |...| ... | | ... | ... | // |n+1| Object* param_n_map | | n-1 | the_hole | // +---------------------------+ | n | element_1 | // | ... | ... | // |n+m-1| element_m | // +-----------------+ // // Parameter maps give the index into the provided context. If a map entry is // the_hole it means that the given entry has been deleted from the arguments // object. // The arguments backing store kind depends on the ElementsKind of the outer // JSArgumentsObject: // - FAST_SLOPPY_ARGUMENTS_ELEMENTS: HOLEY_ELEMENTS // - SLOW_SLOPPY_ARGUMENTS_ELEMENTS: DICTIONARY_ELEMENTS class SloppyArgumentsElements : public FixedArray { public: static const int kContextIndex = 0; static const int kArgumentsIndex = 1; static const uint32_t kParameterMapStart = 2; inline Context* context(); inline FixedArray* arguments(); inline void set_arguments(FixedArray* arguments); inline uint32_t parameter_map_length(); inline Object* get_mapped_entry(uint32_t entry); inline void set_mapped_entry(uint32_t entry, Object* object); DECL_CAST(SloppyArgumentsElements) #ifdef VERIFY_HEAP void SloppyArgumentsElementsVerify(JSObject* holder); #endif private: DISALLOW_IMPLICIT_CONSTRUCTORS(SloppyArgumentsElements); }; // Representation of a slow alias as part of a sloppy arguments objects. // For fast aliases (if HasSloppyArgumentsElements()): // - the parameter map contains an index into the context // - all attributes of the element have default values // For slow aliases (if HasDictionaryArgumentsElements()): // - the parameter map contains no fast alias mapping (i.e. the hole) // - this struct (in the slow backing store) contains an index into the context // - all attributes are available as part if the property details class AliasedArgumentsEntry : public Struct { public: inline int aliased_context_slot() const; inline void set_aliased_context_slot(int count); DECL_CAST(AliasedArgumentsEntry) // Dispatched behavior. DECL_PRINTER(AliasedArgumentsEntry) DECL_VERIFIER(AliasedArgumentsEntry) static const int kAliasedContextSlot = HeapObject::kHeaderSize; static const int kSize = kAliasedContextSlot + kPointerSize; private: DISALLOW_IMPLICIT_CONSTRUCTORS(AliasedArgumentsEntry); }; } // namespace internal } // namespace v8 #include "src/objects/object-macros-undef.h" #endif // V8_OBJECTS_ARGUMENTS_H_