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//===-- ProtocolConformanceAnalysis.cpp - Protocol Conformance Analysis ---===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
// This analysis collects a set of nominal types (classes, structs, and enums)
// that conform to a protocol during whole module compilation. We only track
// protocols that are non-public.
#include "swift/SILOptimizer/Analysis/ProtocolConformanceAnalysis.h"
#include "swift/AST/ASTContext.h"
#include "swift/AST/ASTWalker.h"
#include "swift/AST/Module.h"
#include "swift/AST/ProtocolConformance.h"
#include "swift/SIL/SILInstruction.h"
#include "swift/SIL/SILModule.h"
#include "swift/SIL/SILValue.h"
using namespace swift;
namespace {
/// A helper class to collect all nominal type declarations.
class NominalTypeWalker : public ASTWalker {
ProtocolConformanceAnalysis::ProtocolConformanceMap &ProtocolConformanceCache;
public:
NominalTypeWalker(ProtocolConformanceAnalysis::ProtocolConformanceMap
&ProtocolConformanceCache)
: ProtocolConformanceCache(ProtocolConformanceCache) {}
/// Walk everything in a macro
MacroWalking getMacroWalkingBehavior() const override {
return MacroWalking::ArgumentsAndExpansion;
}
PreWalkAction walkToDeclPre(Decl *D) override {
/// (1) Walk over all NominalTypeDecls to determine conformances.
if (auto *NTD = dyn_cast<NominalTypeDecl>(D)) {
if (!isa<ProtocolDecl>(NTD)) {
auto Protocols = NTD->getAllProtocols();
for (auto &Protocol : Protocols) {
if (Protocol->getEffectiveAccess() <= AccessLevel::Internal) {
ProtocolConformanceCache[Protocol].push_back(NTD);
}
}
}
}
/// (2) Walk over all ExtensionDecls to determine conformances.
if (auto *e = dyn_cast<ExtensionDecl>(D)) {
auto *ntd = e->getExtendedNominal();
if (ntd && !isa<ProtocolDecl>(ntd)) {
for (auto *conformance : e->getLocalConformances()) {
if (isa<NormalProtocolConformance>(conformance)) {
auto *proto = conformance->getProtocol();
if (proto->getEffectiveAccess() <= AccessLevel::Internal) {
ProtocolConformanceCache[proto].push_back(ntd);
}
}
}
}
}
return Action::Continue();
}
};
} // end anonymous namespace
// FIXME: This could be implemented as a request.
void ProtocolConformanceAnalysis::populateConformanceCacheIfNecessary() {
if (ProtocolConformanceCache.has_value())
return;
ProtocolConformanceCache.emplace();
// We only do this in Whole-Module compilation mode.
if (!M->isWholeModule())
return;
// Process all types implementing protocols.
SmallVector<Decl *, 32> Decls;
// Find all top level declarations.
M->getSwiftModule()->getTopLevelDecls(Decls);
/// This operation is quadratic and should only be performed
/// in whole module compilation!
NominalTypeWalker Walker(*ProtocolConformanceCache);
for (auto *D : Decls) {
D->walk(Walker);
}
}
/// Recursively traverse the conformance lists to determine sole conforming
/// class, struct or enum type.
NominalTypeDecl *
ProtocolConformanceAnalysis::findSoleConformingType(ProtocolDecl *Protocol) {
/// First check in the SoleConformingTypeCache.
auto SoleConformingTypeIt = SoleConformingTypeCache.find(Protocol);
if (SoleConformingTypeIt != SoleConformingTypeCache.end())
return SoleConformingTypeIt->second;
SmallVector<ProtocolDecl *, 8> PDWorkList;
SmallPtrSet<ProtocolDecl *, 8> VisitedPDs;
NominalTypeDecl *SoleConformingNTD = nullptr;
PDWorkList.push_back(Protocol);
while (!PDWorkList.empty()) {
auto *PD = PDWorkList.pop_back_val();
// Protocols must have internal or lower access.
if (PD->getEffectiveAccess() > AccessLevel::Internal) {
return nullptr;
}
VisitedPDs.insert(PD);
auto NTDList = getConformances(PD);
for (auto *ConformingNTD : NTDList) {
// Recurse on protocol types.
if (auto *Proto = dyn_cast<ProtocolDecl>(ConformingNTD)) {
// Ignore visited protocol decls.
if (!VisitedPDs.count(Proto))
PDWorkList.push_back(Proto);
} else { // Classes, Structs and Enums are added here.
// Bail if more than one conforming types were found.
if (SoleConformingNTD && ConformingNTD != SoleConformingNTD) {
return nullptr;
} else {
SoleConformingNTD = ConformingNTD;
}
}
}
}
// Bail if we did not find a sole conforming type.
if (!SoleConformingNTD)
return nullptr;
// Generic declarations are ignored.
if (SoleConformingNTD->isGenericContext()) {
return nullptr;
}
// Populate SoleConformingTypeCache.
SoleConformingTypeCache.insert(std::pair<ProtocolDecl *, NominalTypeDecl *>(
Protocol, SoleConformingNTD));
// Return SoleConformingNTD.
return SoleConformingNTD;
}
// Wrapper function to findSoleConformingType that checks for additional
// constraints for classes using ClassHierarchyAnalysis.
bool ProtocolConformanceAnalysis::getSoleConformingType(
ProtocolDecl *Protocol, ClassHierarchyAnalysis *CHA, CanType &ConcreteType) {
// Determine the sole conforming type.
auto *NTD = findSoleConformingType(Protocol);
if (!NTD)
return false;
// Sole conforming class should not be open access or have any derived class.
ClassDecl *CD;
if ((CD = dyn_cast<ClassDecl>(NTD)) &&
(CD->getEffectiveAccess() == AccessLevel::Open ||
CHA->hasKnownDirectSubclasses(CD))) {
return false;
}
// Save the concrete type.
ConcreteType = NTD->getDeclaredType()->getCanonicalType();
return true;
}
ProtocolConformanceAnalysis::~ProtocolConformanceAnalysis() {}
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