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//===--- MetadataSource.h - structure for the source of metadata *- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
#ifndef SWIFT_IRGEN_METADATA_SOURCE_H
#define SWIFT_IRGEN_METADATA_SOURCE_H
#include "swift/AST/Types.h"
namespace swift {
namespace irgen {
class MetadataSource {
public:
enum class Kind {
/// Metadata is derived from a source class pointer.
ClassPointer,
/// Metadata is derived from a type metadata pointer.
Metadata,
/// Metadata is derived from the origin type parameter.
GenericLValueMetadata,
/// Metadata is obtained directly from the from a Self metadata
/// parameter passed via the WitnessMethod convention.
SelfMetadata,
/// Metadata is derived from the Self witness table parameter
/// passed via the WitnessMethod convention.
SelfWitnessTable,
/// Metadata is obtained directly from the FixedType indicated. Used with
/// Objective-C generics, where the actual argument is erased at runtime
/// and its existential bound is used instead.
ErasedTypeMetadata,
};
static bool requiresSourceIndex(Kind kind) {
return (kind == Kind::ClassPointer ||
kind == Kind::Metadata ||
kind == Kind::GenericLValueMetadata);
}
static bool requiresFixedType(Kind kind) {
return (kind == Kind::ErasedTypeMetadata);
}
enum : unsigned { InvalidSourceIndex = ~0U };
private:
/// The kind of source this is.
Kind TheKind;
/// For ClassPointer, Metadata, and GenericLValueMetadata, the source index;
/// for ErasedTypeMetadata, the type; for others, Index should be set to
/// InvalidSourceIndex.
union {
unsigned Index;
CanType FixedType;
};
public:
CanType Type;
MetadataSource(Kind kind, CanType type)
: TheKind(kind), Index(InvalidSourceIndex), Type(type)
{
assert(!requiresSourceIndex(kind) && !requiresFixedType(kind));
}
MetadataSource(Kind kind, CanType type, unsigned index)
: TheKind(kind), Index(index), Type(type) {
assert(requiresSourceIndex(kind));
assert(index != InvalidSourceIndex);
}
MetadataSource(Kind kind, CanType type, CanType fixedType)
: TheKind(kind), FixedType(fixedType), Type(type) {
assert(requiresFixedType(kind));
}
Kind getKind() const { return TheKind; }
unsigned getParamIndex() const {
assert(requiresSourceIndex(getKind()));
return Index;
}
CanType getFixedType() const {
assert(requiresFixedType(getKind()));
return FixedType;
}
};
} // end namespace irgen
} // end namespace swift
#endif
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