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This will be used to help IRGen record protocol requirements with resilient default implementations in protocol metadata. To enable testing before all the Sema support is in place, this patch adds SIL parser, printer and verifier support for default witness tables. For now, SILGen emits empty default witness tables for protocol declarations in resilient modules, and IRGen ignores them when emitting protocol metadata.
117 lines
3.9 KiB
C++
117 lines
3.9 KiB
C++
//===--- SILWitnessVisitor.h - Witness method table visitor -----*- 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 - 2016 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 http://swift.org/LICENSE.txt for license information
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// See http://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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// This file defines the SILWitnessVisitor class, which is used to generate and
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// perform lookups in witness method tables for protocols and protocol
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// conformances.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_SIL_SILWITNESSVISITOR_H
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#define SWIFT_SIL_SILWITNESSVISITOR_H
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#include "swift/AST/ASTVisitor.h"
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#include "swift/AST/Decl.h"
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#include "swift/AST/Types.h"
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#include "swift/SIL/TypeLowering.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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namespace swift {
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/// A CRTP class for visiting the witnesses of a protocol.
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///
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/// The design here is that each entry (or small group of entries)
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/// gets turned into a call to the implementation class describing
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/// the exact variant of witness. For example, for member
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/// variables, there should be separate callbacks for adding a
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/// getter/setter pair, for just adding a getter, and for adding a
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/// physical projection (if we decide to support that).
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///
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/// You must override the following methods:
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/// - addOutOfLineBaseProtocol()
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/// - addMethod()
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/// - addConstructor()
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/// - addAssociatedType()
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template <class T> class SILWitnessVisitor : public ASTVisitor<T> {
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T &asDerived() { return *static_cast<T*>(this); }
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public:
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void visitProtocolDecl(ProtocolDecl *protocol) {
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// Visit inherited protocols.
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// TODO: We need to figure out all the guarantees we want here.
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// It would be abstractly good to allow conversion to a base
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// protocol to be trivial, but it's not clear that there's
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// really a structural guarantee we can rely on here.
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for (auto baseProto : protocol->getInheritedProtocols(nullptr)) {
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// ObjC protocols do not have witnesses.
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if (!Lowering::TypeConverter::protocolRequiresWitnessTable(baseProto))
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continue;
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asDerived().addOutOfLineBaseProtocol(baseProto);
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}
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/// Visit the witnesses for the direct members of a protocol.
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for (Decl *member : protocol->getMembers())
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ASTVisitor<T>::visit(member);
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}
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/// Fallback for unexpected protocol requirements.
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void visitDecl(Decl *d) {
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d->print(llvm::errs());
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llvm_unreachable("unhandled protocol requirement");
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}
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void visitAbstractStorageDecl(AbstractStorageDecl *sd) {
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asDerived().addMethod(sd->getGetter());
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if (sd->isSettable(sd->getDeclContext())) {
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asDerived().addMethod(sd->getSetter());
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if (sd->getMaterializeForSetFunc())
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asDerived().addMethod(sd->getMaterializeForSetFunc());
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}
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}
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void visitConstructorDecl(ConstructorDecl *cd) {
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asDerived().addConstructor(cd);
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}
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void visitFuncDecl(FuncDecl *func) {
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// Accessors are emitted by their var/subscript declaration.
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if (func->isAccessor())
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return;
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asDerived().addMethod(func);
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}
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void visitAssociatedTypeDecl(AssociatedTypeDecl *td) {
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SmallVector<ProtocolDecl *, 4> protos;
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for (auto p : td->getConformingProtocols(nullptr))
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protos.push_back(p);
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ProtocolType::canonicalizeProtocols(protos);
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asDerived().addAssociatedType(td, protos);
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}
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void visitPatternBindingDecl(PatternBindingDecl *pbd) {
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// We only care about the contained VarDecls.
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}
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void visitIfConfigDecl(IfConfigDecl *icd) {
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// We only care about the active members, which were already subsumed by the
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// enclosing type.
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}
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};
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} // end namespace swift
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#endif
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