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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 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
//
//===----------------------------------------------------------------------===//
#include "Private.h"
#include "SwiftHashableSupport.h"
#include "SwiftValue.h"
#include "swift/Basic/Lazy.h"
#include "swift/Runtime/Casting.h"
#include "swift/Runtime/Concurrent.h"
#include "swift/Runtime/Config.h"
#include "swift/Runtime/Debug.h"
#include "swift/Runtime/HeapObject.h"
#include "swift/shims/Visibility.h"
#include <new>
using namespace swift;
using namespace swift::hashable_support;
namespace {
struct HashableConformanceKey {
/// The lookup key, the metadata of a type that is possibly derived
/// from a type that conforms to `Hashable`.
const Metadata *derivedType;
friend llvm::hash_code hash_value(const HashableConformanceKey &key) {
return llvm::hash_value(key.derivedType);
}
};
struct HashableConformanceEntry {
/// The lookup key, the metadata of a type that is possibly derived
/// from a type that conforms to `Hashable`.
const Metadata *derivedType;
/// The highest (closest to the root) type in the superclass chain
/// that conforms to `Hashable`.
///
/// Always non-NULL. We don't cache negative responses so that we
/// don't have to deal with cache invalidation.
const Metadata *baseTypeThatConformsToHashable;
HashableConformanceEntry(HashableConformanceKey key,
const Metadata *baseTypeThatConformsToHashable)
: derivedType(key.derivedType),
baseTypeThatConformsToHashable(baseTypeThatConformsToHashable) {}
bool matchesKey(const HashableConformanceKey &key) {
return derivedType == key.derivedType;
}
friend llvm::hash_code hash_value(const HashableConformanceEntry &value) {
return hash_value(HashableConformanceKey{value.derivedType});
}
static size_t
getExtraAllocationSize(HashableConformanceKey key,
const Metadata *baseTypeThatConformsToHashable) {
return 0;
}
size_t getExtraAllocationSize() const {
return 0;
}
};
} // end unnamed namespace
// FIXME(performance): consider merging this cache into the regular
// protocol conformance cache.
static ConcurrentReadableHashMap<HashableConformanceEntry> HashableConformances;
template <bool KnownToConformToHashable>
SWIFT_ALWAYS_INLINE static const Metadata *
findHashableBaseTypeImpl(const Metadata *type) {
// Check the cache first.
{
auto snapshot = HashableConformances.snapshot();
if (const HashableConformanceEntry *entry =
snapshot.find(HashableConformanceKey{type})) {
return entry->baseTypeThatConformsToHashable;
}
}
auto witnessTable =
swift_conformsToProtocolCommon(type, &HashableProtocolDescriptor);
if (!KnownToConformToHashable && !witnessTable) {
// Don't cache the negative response because we don't invalidate
// this cache when a new conformance is loaded dynamically.
return nullptr;
}
// By this point, `type` is known to conform to `Hashable`.
#if SWIFT_STDLIB_USE_RELATIVE_PROTOCOL_WITNESS_TABLES
const auto *conformance = lookThroughOptionalConditionalWitnessTable(
reinterpret_cast<const RelativeWitnessTable*>(witnessTable))
->getDescription();
#else
const auto *conformance = witnessTable->getDescription();
#endif
const Metadata *baseTypeThatConformsToHashable =
findConformingSuperclass(type, conformance);
HashableConformanceKey key{type};
HashableConformances.getOrInsert(key, [&](HashableConformanceEntry *entry,
bool created) {
if (created)
::new (entry) HashableConformanceEntry(key, baseTypeThatConformsToHashable);
return true; // Keep the new entry.
});
return baseTypeThatConformsToHashable;
}
/// Find the base type that introduces the `Hashable` conformance.
/// Because the provided type is known to conform to `Hashable`, this
/// function always returns non-null.
///
/// - Precondition: `type` conforms to `Hashable` (not checked).
const Metadata *swift::hashable_support::findHashableBaseTypeOfHashableType(
const Metadata *type) {
auto result =
findHashableBaseTypeImpl</*KnownToConformToHashable=*/ true>(type);
assert(result && "Known-hashable types should have a `Hashable` conformance.");
return result;
}
/// Find the base type that introduces the `Hashable` conformance.
/// If `type` does not conform to `Hashable`, `nullptr` is returned.
const Metadata *swift::hashable_support::findHashableBaseType(
const Metadata *type) {
return findHashableBaseTypeImpl</*KnownToConformToHashable=*/ false>(type);
}
// internal func _makeAnyHashableUsingDefaultRepresentation<H : Hashable>(
// of value: H,
// storingResultInto result: UnsafeMutablePointer<AnyHashable>)
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERNAL
void _swift_makeAnyHashableUsingDefaultRepresentation(
const OpaqueValue *value,
const void *anyHashableResultPointer,
const Metadata *T,
const WitnessTable *hashableWT
);
// public func _makeAnyHashableUpcastingToHashableBaseType<H : Hashable>(
// _ value: H,
// storingResultInto result: UnsafeMutablePointer<AnyHashable>)
SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_SPI
void _swift_makeAnyHashableUpcastingToHashableBaseType(
OpaqueValue *value,
const void *anyHashableResultPointer,
const Metadata *type,
const WitnessTable *hashableWT
) {
switch (type->getKind()) {
case MetadataKind::Class:
case MetadataKind::ObjCClassWrapper:
case MetadataKind::ForeignClass:
case MetadataKind::ForeignReferenceType: {
#if SWIFT_OBJC_INTEROP
id srcObject;
memcpy(&srcObject, value, sizeof(id));
// Do we have a __SwiftValue?
if (__SwiftValue *srcSwiftValue = getAsSwiftValue(srcObject)) {
// If so, extract the boxed value and try to cast it.
const Metadata *unboxedType;
const OpaqueValue *unboxedValue;
std::tie(unboxedType, unboxedValue) =
getValueFromSwiftValue(srcSwiftValue);
if (auto unboxedHashableWT =
swift_conformsToProtocolCommon(unboxedType, &HashableProtocolDescriptor)) {
_swift_makeAnyHashableUpcastingToHashableBaseType(
const_cast<OpaqueValue *>(unboxedValue), anyHashableResultPointer,
unboxedType, unboxedHashableWT);
return;
}
}
#endif
_swift_makeAnyHashableUsingDefaultRepresentation(
value, anyHashableResultPointer,
findHashableBaseTypeOfHashableType(type),
hashableWT);
return;
}
default:
_swift_makeAnyHashableUsingDefaultRepresentation(
value, anyHashableResultPointer, type, hashableWT);
return;
}
}
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