// 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/fixed-array.h"

#include "src/objects/hole.h"

#include "src/objects/js-objects.h"

#include "src/objects/struct.h"

// Has to be the last include (doesn't have include guards):

#include "src/objects/object-macros.h"

namespace v8 {

namespace internal {

class StructBodyDescriptor;

#include "torque-generated/src/objects/arguments-tq.inc"

// Superclass for all objects with instance type {JS_ARGUMENTS_OBJECT_TYPE}

class JSArgumentsObject

: public TorqueGeneratedJSArgumentsObject<JSArgumentsObject, JSObject> {

public:

DECL_VERIFIER(JSArgumentsObject)

DECL_PRINTER(JSArgumentsObject)

TQ_OBJECT_CONSTRUCTORS(JSArgumentsObject)

};

// JSSloppyArgumentsObject is just a JSArgumentsObject with specific initial

// map. This initial map adds in-object properties for "length" and "callee".

class JSSloppyArgumentsObject

: public TorqueGeneratedJSSloppyArgumentsObject<JSSloppyArgumentsObject,

JSArgumentsObject> {

public:

// Indices of in-object properties.

static const int kLengthIndex = 0;

static const int kCalleeIndex = kLengthIndex + 1;

private:

DISALLOW_IMPLICIT_CONSTRUCTORS(JSSloppyArgumentsObject);

};

// JSStrictArgumentsObject is just a JSArgumentsObject with specific initial

// map. This initial map adds an in-object property for "length".

class JSStrictArgumentsObject

: public TorqueGeneratedJSStrictArgumentsObject<JSStrictArgumentsObject,

JSArgumentsObject> {

public:

// Indices of in-object properties.

static const int kLengthIndex = 0;

static_assert(kLengthIndex == JSSloppyArgumentsObject::kLengthIndex);

private:

DISALLOW_IMPLICIT_CONSTRUCTORS(JSStrictArgumentsObject);

};

// 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 TorqueGeneratedAliasedArgumentsEntry<AliasedArgumentsEntry,

Struct> {

public:

using BodyDescriptor = StructBodyDescriptor;

TQ_OBJECT_CONSTRUCTORS(AliasedArgumentsEntry)

};

class SloppyArgumentsElementsShape final : public AllStatic {

public:

using ElementT = UnionOf<Smi, Hole>;

using CompressionScheme = V8HeapCompressionScheme;

static constexpr RootIndex kMapRootIndex =

RootIndex::kSloppyArgumentsElementsMap;

static constexpr bool kLengthEqualsCapacity = true;

V8_ARRAY_EXTRA_FIELDS({

TaggedMember<Context> context_;

TaggedMember<UnionOf<FixedArray, NumberDictionary>> arguments_;

});

};

// Helper class to access FAST_ and SLOW_SLOPPY_ARGUMENTS_ELEMENTS, dividing

// arguments into two types for a given SloppyArgumentsElements object:

// mapped and unmapped.

//

// For clarity SloppyArgumentsElements fields are qualified with "elements."

// below.

//

// Mapped arguments are actual arguments. Unmapped arguments are values added

// to the arguments object after it was created for the call. Mapped arguments

// are stored in the context at indexes given by elements.mapped_entries[key].

// Unmapped arguments are stored as regular indexed properties in the arguments

// array which can be accessed from elements.arguments.

//

// elements.length is min(number_of_actual_arguments,

// number_of_formal_arguments) for a concrete call to a function.

//

// Once a SloppyArgumentsElements is generated, lookup of an argument with index

// |key| in |elements| works as follows:

//

// If key >= elements.length then attempt to look in the unmapped arguments

// array and return the value at key, missing to the runtime if the unmapped

// arguments array is not a fixed array or if key >= elements.arguments.length.

//

// Otherwise, t = elements.mapped_entries[key]. If t is the hole, then the

// entry has been deleted from the arguments object, and value is looked up in

// the unmapped arguments array, as described above. Otherwise, t is a Smi

// index into the context array specified at elements.context, and the return

// value is elements.context[t].

//

// A graphic representation of a SloppyArgumentsElements object and a

// corresponding unmapped arguments FixedArray:

//

// SloppyArgumentsElements

// +---+-----------------------+

// | Context context |

// +---------------------------+

// | FixedArray arguments +----+ HOLEY_ELEMENTS

// +---------------------------+ v-----+-----------+

// | 0 | Object mapped_entries | | 0 | the_hole |

// |...| ... | | ... | ... |

// |n-1| Object mapped_entries | | n-1 | the_hole |

// +---------------------------+ | n | element_1 |

// | ... | ... |

// |n+m-1| element_m |

// +-----------------+

//

// The elements.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 TaggedArrayBase<SloppyArgumentsElements,

SloppyArgumentsElementsShape> {

public:

inline Tagged<Context> context() const;

inline void set_context(Tagged<Context> value,

WriteBarrierMode mode = UPDATE_WRITE_BARRIER);

inline Tagged<UnionOf<FixedArray, NumberDictionary>> arguments() const;

inline void set_arguments(Tagged<UnionOf<FixedArray, NumberDictionary>> value,

WriteBarrierMode mode = UPDATE_WRITE_BARRIER);

// Returns: Smi|TheHole.

inline Tagged<UnionOf<Smi, Hole>> mapped_entries(int index,

RelaxedLoadTag) const;

inline void set_mapped_entries(int index, Tagged<UnionOf<Smi, Hole>> value);

inline void set_mapped_entries(int index, Tagged<UnionOf<Smi, Hole>> value,

RelaxedStoreTag);

DECL_PRINTER(SloppyArgumentsElements)

DECL_VERIFIER(SloppyArgumentsElements)

class BodyDescriptor;

};

} // namespace internal

} // namespace v8

#include "src/objects/object-macros-undef.h"

#endif // V8_OBJECTS_ARGUMENTS_H_