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Implement computeUnalignedFieldStartOffset

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Implement computeUnalignedFieldStartOffset as an alternative way to
finding out the start of the fields that belong to the instance when
reading the field's start from binary is not possible (for example,
embedded Swift doesn't emit any reflection metadata on the binary).
This commit is contained in:
Augusto Noronha
2024-02-01 16:05:38 -08:00
parent 7b6f45c59a
commit 18a80f8941
2 changed files with 37 additions and 4 deletions
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39
include/swift/RemoteInspection/ReflectionContext.h
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@@ -908,7 +908,7 @@ public:
// Figure out where the stored properties of this class begin
// by looking at the size of the superclass
auto start =
this->readInstanceStartAndAlignmentFromClassMetadata(MetadataAddress);
this->readInstanceStartFromClassMetadata(MetadataAddress);
// Perform layout
if (start)
@@ -1202,8 +1202,41 @@ public:
}
}
const RecordTypeInfo *getRecordTypeInfo(const TypeRef *TR,
remote::TypeInfoProvider *ExternalTypeInfo) {
/// Given a typeref, attempt to calculate the unaligned start of this
/// instance's fields. For example, for a type without a superclass, the start
/// of the instance fields would after the word for the isa pointer and the
/// word for the refcount field. For a subclass the start would be the after
/// the superclass's fields. For a version of this function that performs the
/// same job but starting out with an instance pointer check
/// MetadataReader::readInstanceStartFromClassMetadata.
llvm::Optional<unsigned>
computeUnalignedFieldStartOffset(const TypeRef *TR) {
size_t isaAndRetainCountSize = sizeof(StoredSize) + sizeof(long long);
const TypeRef *superclass = getBuilder().lookupSuperclass(TR);
if (!superclass)
// If there is no superclass the stat of the instance's field is right
// after the isa and retain fields.
return isaAndRetainCountSize;
auto superclassStart =
computeUnalignedFieldStartOffset(superclass);
if (!superclassStart)
return llvm::None;
auto *superTI = getBuilder().getTypeConverter().getClassInstanceTypeInfo(
superclass, *superclassStart, nullptr);
if (!superTI)
return llvm::None;
// The start of the subclass's fields is right after the super class's ones.
size_t start = superTI->getSize();
return start;
}
const RecordTypeInfo *
getRecordTypeInfo(const TypeRef *TR,
remote::TypeInfoProvider *ExternalTypeInfo) {
auto *TypeInfo = getTypeInfo(TR, ExternalTypeInfo);
return dyn_cast_or_null<const RecordTypeInfo>(TypeInfo);
}