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db8f23df74
- `swift_getForeignTypeMetadata` is now a request/response function. - The initialization function is now a completion function, and the pointer to it has moved into the type descriptor. - The cache variable is no longer part of the ABI; it's an implementation detail of the access function. - The two points above mean that there is no special header on foreign type metadata and therefore that they can be marked constant when there isn't something about them that needs to be initialized. The only foreign-metadata initialization we actually do right now is of the superclass field of a foreign class, and since that relationship is a proper DAG, it's not actually possible to have recursive initialization problems. But this is the right long-term thing to do, and it removes one of the last two clients of once-based initialization.
78 lines
2.3 KiB
C++
78 lines
2.3 KiB
C++
//===-- ForeignClassMetadataVisitor.h - foreign class 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 foreign class metadata.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_IRGEN_FOREIGNCLASSMETADATAVISITOR_H
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#define SWIFT_IRGEN_FOREIGNCLASSMETADATAVISITOR_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 layout class for foreign class metadata.
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template <class Impl>
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class ForeignClassMetadataVisitor
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: public NominalMetadataVisitor<Impl> {
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using super = NominalMetadataVisitor<Impl>;
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protected:
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ClassDecl *Target;
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using super::asImpl;
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public:
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ForeignClassMetadataVisitor(IRGenModule &IGM, ClassDecl *target)
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: super(IGM), Target(target) {}
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void layout() {
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super::layout();
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asImpl().addNominalTypeDescriptor();
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asImpl().addSuperclass();
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asImpl().addReservedWord();
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}
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CanType getTargetType() const {
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return Target->getDeclaredType()->getCanonicalType();
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}
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};
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/// An "implementation" of ForeignClassMetadataVisitor 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 ForeignClassMetadataScanner : public ForeignClassMetadataVisitor<Impl> {
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using super = ForeignClassMetadataVisitor<Impl>;
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protected:
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Size NextOffset = Size(0);
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ForeignClassMetadataScanner(IRGenModule &IGM, ClassDecl *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 addSuperclass() { addPointer(); }
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void addReservedWord() { addPointer(); }
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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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};
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} // end namespace irgen
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} // end namespace swift
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#endif // SWIFT_IRGEN_FOREIGNCLASSMETADATAVISITOR_H
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