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7068141770
Prespecialized records contain direct references to the generic arguments and protocol witnesses with which it is specialized for now. Both prespecialized records and the records that are specialized at runtime gain a trailing pointer-sized flagset. For now, the flags in it include whether the record was prespecialized and whether it was known to be canonical at compile time (which is true for prespecialized records within the module which defines the type whose metadata is specialized since in those cases the metadata accessor can be modified). rdar://problem/56960307
120 lines
3.4 KiB
C++
120 lines
3.4 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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#include "swift/AST/IRGenOptions.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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if (asImpl().hasTrailingFlags())
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asImpl().addTrailingFlags();
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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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bool hasTrailingFlags() {
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return Target->isGenericContext() &&
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IGM.shouldPrespecializeGenericMetadata();
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}
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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(GenericRequirement requirement) { addPointer(); }
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void addGenericWitnessTable(GenericRequirement requirement) { 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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void addTrailingFlags() { 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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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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