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41aebf8e5a
We don't need to substitute the superclass type as we walk up a class hierarchy, or look up the generic parameters and conformances to check if they're concrete, since we're always just emitting null pointers in place of the generic parameters and requirements, to be filled at runtime. Also, don't leave space for generic parameters and requirements from Objective-C superclasses, since that's not how they're represented.
109 lines
3.1 KiB
C++
109 lines
3.1 KiB
C++
//===--- StructMetadataVisitor.h - CRTP for struct metadata ------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// A CRTP class useful for laying out struct metadata.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_IRGEN_STRUCTMETADATALAYOUT_H
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#define SWIFT_IRGEN_STRUCTMETADATALAYOUT_H
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#include "NominalMetadataVisitor.h"
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namespace swift {
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namespace irgen {
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/// A CRTP class for laying out struct metadata.
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///
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/// This produces an object corresponding to the StructMetadata type.
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/// It does not itself doing anything special for metadata templates.
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template <class Impl> class StructMetadataVisitor
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: public NominalMetadataVisitor<Impl> {
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using super = NominalMetadataVisitor<Impl>;
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protected:
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using super::IGM;
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using super::asImpl;
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/// The struct.
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StructDecl *const Target;
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StructMetadataVisitor(IRGenModule &IGM, StructDecl *target)
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: super(IGM), Target(target) {}
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public:
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void layout() {
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// Metadata header.
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super::layout();
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// StructMetadata header.
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asImpl().addNominalTypeDescriptor();
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// Everything after this is type-specific.
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asImpl().noteStartOfTypeSpecificMembers();
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// Generic arguments.
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// This must always be the first piece of trailing data.
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asImpl().addGenericFields(Target);
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// Struct field offsets.
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asImpl().noteStartOfFieldOffsets();
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for (VarDecl *prop : Target->getStoredProperties())
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asImpl().addFieldOffset(prop);
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asImpl().noteEndOfFieldOffsets();
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}
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// Note the start of the field offset vector.
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void noteStartOfFieldOffsets() {}
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// Note the end of the field offset vector.
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void noteEndOfFieldOffsets() {}
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};
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/// An "implementation" of StructMetadataVisitor that just scans through
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/// the metadata layout, maintaining the offset of the next field.
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template <class Impl>
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class StructMetadataScanner : public StructMetadataVisitor<Impl> {
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using super = StructMetadataVisitor<Impl>;
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protected:
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Size NextOffset = Size(0);
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StructMetadataScanner(IRGenModule &IGM, StructDecl *target)
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: super(IGM, target) {}
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public:
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void addMetadataFlags() { addPointer(); }
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void addValueWitnessTable() { addPointer(); }
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void addNominalTypeDescriptor() { addPointer(); }
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void addFieldOffset(VarDecl *) { addInt32(); }
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void addGenericArgument() { addPointer(); }
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void addGenericWitnessTable() { addPointer(); }
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void noteStartOfTypeSpecificMembers() {}
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void noteEndOfFieldOffsets() {
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NextOffset = NextOffset.roundUpToAlignment(super::IGM.getPointerAlignment());
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}
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private:
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void addPointer() {
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NextOffset += super::IGM.getPointerSize();
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}
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void addInt32() { NextOffset += Size(4); }
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};
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} // end namespace irgen
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} // end namespace swift
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#endif
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