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Account for whether artificial subclasses are skipped on type caching #68404

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Sep 12, 2023
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Account for whether artificial subclasses are skipped on type caching #68404

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53 changes: 35 additions & 18 deletions include/swift/Remote/MetadataReader.h
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,8 @@
#ifndef SWIFT_REMOTE_METADATAREADER_H
#define SWIFT_REMOTE_METADATAREADER_H

#include "llvm/ADT/Hashing.h"

#include "swift/Runtime/Metadata.h"
#include "swift/Remote/MemoryReader.h"
#include "swift/Demangling/Demangler.h"
Expand Down Expand Up @@ -193,8 +195,18 @@ class MetadataReader {
/// amounts of data when we encounter corrupt values for sizes/counts.
static const uint64_t MaxMetadataSize = 1048576; // 1MB

/// A cache of built types, keyed by the address of the type.
std::unordered_map<StoredPointer, BuiltType> TypeCache;
/// Define a has function for a std::pair<StoredPointer, bool>
struct TypeCacheKeyHash {
std::size_t operator()(const std::pair<StoredPointer, bool> &x) const {
return llvm::hash_combine(x.first, x.second);
}
};

/// A cache of built types, keyed by the address of the type and whether the
/// request ignored articial superclasses or not.
std::unordered_map<std::pair<StoredPointer, bool>, BuiltType,
TypeCacheKeyHash>
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Just curious: If we are using the LLVM libraries anyway, why not use a DenseMap?

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Looks like we can, I'll change this in a separate patch.

TypeCache;

using MetadataRef = RemoteRef<const TargetMetadata<Runtime>>;
using OwnedMetadataRef = MemoryReader::ReadBytesResult;
Expand Down Expand Up @@ -821,7 +833,9 @@ class MetadataReader {
readTypeFromMetadata(StoredPointer MetadataAddress,
bool skipArtificialSubclasses = false,
int recursion_limit = defaultTypeRecursionLimit) {
auto Cached = TypeCache.find(MetadataAddress);
std::pair<StoredPointer, bool> TypeCacheKey(MetadataAddress,
skipArtificialSubclasses);
auto Cached = TypeCache.find(TypeCacheKey);
if (Cached != TypeCache.end())
return Cached->second;

Expand All @@ -841,7 +855,7 @@ class MetadataReader {
// Insert a negative result into the cache now so that, if we recur with
// the same address, we will return the negative result with the check
// just above.
TypeCache.insert({MetadataAddress, BuiltType()});
TypeCache.insert({TypeCacheKey, BuiltType()});

auto Meta = readMetadata(MetadataAddress);
if (!Meta) return BuiltType();
Expand Down Expand Up @@ -890,7 +904,7 @@ class MetadataReader {

auto BuiltTuple =
Builder.createTupleType(elementTypes, labels);
TypeCache[MetadataAddress] = BuiltTuple;
TypeCache[TypeCacheKey] = BuiltTuple;
return BuiltTuple;
}
case MetadataKind::Function: {
Expand Down Expand Up @@ -947,7 +961,7 @@ class MetadataReader {

auto BuiltFunction = Builder.createFunctionType(
Parameters, Result, flags, diffKind, globalActor);
TypeCache[MetadataAddress] = BuiltFunction;
TypeCache[TypeCacheKey] = BuiltFunction;
return BuiltFunction;
}
case MetadataKind::Existential: {
Expand Down Expand Up @@ -998,7 +1012,7 @@ class MetadataReader {
}
auto BuiltExist = Builder.createProtocolCompositionType(
Protocols, SuperclassType, HasExplicitAnyObject);
TypeCache[MetadataAddress] = BuiltExist;
TypeCache[TypeCacheKey] = BuiltExist;
return BuiltExist;
}
case MetadataKind::ExtendedExistential: {
Expand Down Expand Up @@ -1076,7 +1090,7 @@ class MetadataReader {
}
}

TypeCache[MetadataAddress] = builtProto;
TypeCache[TypeCacheKey] = builtProto;
return builtProto;
}

Expand All @@ -1086,7 +1100,7 @@ class MetadataReader {
readTypeFromMetadata(Metatype->InstanceType, false, recursion_limit);
if (!Instance) return BuiltType();
auto BuiltMetatype = Builder.createMetatypeType(Instance);
TypeCache[MetadataAddress] = BuiltMetatype;
TypeCache[TypeCacheKey] = BuiltMetatype;
return BuiltMetatype;
}
case MetadataKind::ObjCClassWrapper: {
Expand All @@ -1098,7 +1112,7 @@ class MetadataReader {
return BuiltType();

auto BuiltObjCClass = Builder.createObjCClassType(std::move(className));
TypeCache[MetadataAddress] = BuiltObjCClass;
TypeCache[TypeCacheKey] = BuiltObjCClass;
return BuiltObjCClass;
}
case MetadataKind::ExistentialMetatype: {
Expand All @@ -1107,7 +1121,7 @@ class MetadataReader {
readTypeFromMetadata(Exist->InstanceType, false, recursion_limit);
if (!Instance) return BuiltType();
auto BuiltExist = Builder.createExistentialMetatypeType(Instance);
TypeCache[MetadataAddress] = BuiltExist;
TypeCache[TypeCacheKey] = BuiltExist;
return BuiltExist;
}
case MetadataKind::ForeignReferenceType:
Expand All @@ -1131,7 +1145,7 @@ class MetadataReader {
auto name = mangling.result();

auto BuiltForeign = Builder.createForeignClassType(std::move(name));
TypeCache[MetadataAddress] = BuiltForeign;
TypeCache[TypeCacheKey] = BuiltForeign;
return BuiltForeign;
}
case MetadataKind::HeapLocalVariable:
Expand All @@ -1142,7 +1156,7 @@ class MetadataReader {
case MetadataKind::Opaque:
default: {
auto BuiltOpaque = Builder.getOpaqueType();
TypeCache[MetadataAddress] = BuiltOpaque;
TypeCache[TypeCacheKey] = BuiltOpaque;
return BuiltOpaque;
}
}
Expand Down Expand Up @@ -3084,9 +3098,12 @@ class MetadataReader {
// If we've skipped an artificial subclasses, check the cache at
// the superclass. (This also protects against recursion.)
if (skipArtificialSubclasses && metadata != origMetadata) {
auto it = TypeCache.find(getAddress(metadata));
if (it != TypeCache.end())
auto it =
TypeCache.find({getAddress(metadata), skipArtificialSubclasses});
if (it != TypeCache.end()) {
TypeCache.erase({getAddress(origMetadata), skipArtificialSubclasses});
return it->second;
}
}

// Read the nominal type descriptor.
Expand Down Expand Up @@ -3115,12 +3132,12 @@ class MetadataReader {
if (!nominal)
return BuiltType();

TypeCache[getAddress(metadata)] = nominal;
TypeCache[{getAddress(metadata), skipArtificialSubclasses}] = nominal;

// If we've skipped an artificial subclass, remove the
// recursion-protection entry we made for it.
if (skipArtificialSubclasses && metadata != origMetadata) {
TypeCache.erase(getAddress(origMetadata));
TypeCache.erase({getAddress(origMetadata), skipArtificialSubclasses});
}

return nominal;
Expand Down Expand Up @@ -3151,7 +3168,7 @@ class MetadataReader {
skipArtificialSubclasses, recursion_limit);
}

TypeCache[origMetadataPtr] = BuiltObjCClass;
TypeCache[{origMetadataPtr, skipArtificialSubclasses}] = BuiltObjCClass;
return BuiltObjCClass;
}

Expand Down