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