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llvm-for-llvmta/tools/clang/lib/AST/ExternalASTMerger.cpp

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//===- ExternalASTMerger.cpp - Merging External AST Interface ---*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the ExternalASTMerger, which vends a combination of
// ASTs from several different ASTContext/FileManager pairs
//
//===----------------------------------------------------------------------===//
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/ExternalASTMerger.h"
using namespace clang;
namespace {
template <typename T> struct Source {
T t;
Source(T t) : t(t) {}
operator T() { return t; }
template <typename U = T> U &get() { return t; }
template <typename U = T> const U &get() const { return t; }
template <typename U> operator Source<U>() { return Source<U>(t); }
};
typedef std::pair<Source<NamedDecl *>, ASTImporter *> Candidate;
/// For the given DC, return the DC that is safe to perform lookups on. This is
/// the DC we actually want to work with most of the time.
const DeclContext *CanonicalizeDC(const DeclContext *DC) {
if (isa<LinkageSpecDecl>(DC))
return DC->getRedeclContext();
return DC;
}
Source<const DeclContext *>
LookupSameContext(Source<TranslationUnitDecl *> SourceTU, const DeclContext *DC,
ASTImporter &ReverseImporter) {
DC = CanonicalizeDC(DC);
if (DC->isTranslationUnit()) {
return SourceTU;
}
Source<const DeclContext *> SourceParentDC =
LookupSameContext(SourceTU, DC->getParent(), ReverseImporter);
if (!SourceParentDC) {
// If we couldn't find the parent DC in this TranslationUnit, give up.
return nullptr;
}
auto *ND = cast<NamedDecl>(DC);
DeclarationName Name = ND->getDeclName();
auto SourceNameOrErr = ReverseImporter.Import(Name);
if (!SourceNameOrErr) {
llvm::consumeError(SourceNameOrErr.takeError());
return nullptr;
}
Source<DeclarationName> SourceName = *SourceNameOrErr;
DeclContext::lookup_result SearchResult =
SourceParentDC.get()->lookup(SourceName.get());
size_t SearchResultSize = SearchResult.size();
if (SearchResultSize == 0 || SearchResultSize > 1) {
// There are two cases here. First, we might not find the name.
// We might also find multiple copies, in which case we have no
// guarantee that the one we wanted is the one we pick. (E.g.,
// if we have two specializations of the same template it is
// very hard to determine which is the one you want.)
//
// The Origins map fixes this problem by allowing the origin to be
// explicitly recorded, so we trigger that recording by returning
// nothing (rather than a possibly-inaccurate guess) here.
return nullptr;
} else {
NamedDecl *SearchResultDecl = SearchResult[0];
if (isa<DeclContext>(SearchResultDecl) &&
SearchResultDecl->getKind() == DC->getDeclKind())
return cast<DeclContext>(SearchResultDecl)->getPrimaryContext();
return nullptr; // This type of lookup is unsupported
}
}
/// A custom implementation of ASTImporter, for ExternalASTMerger's purposes.
///
/// There are several modifications:
///
/// - It enables lazy lookup (via the HasExternalLexicalStorage flag and a few
/// others), which instructs Clang to refer to ExternalASTMerger. Also, it
/// forces MinimalImport to true, which is necessary to make this work.
/// - It maintains a reverse importer for use with names. This allows lookup of
/// arbitrary names in the source context.
/// - It updates the ExternalASTMerger's origin map as needed whenever a
/// it sees a DeclContext.
class LazyASTImporter : public ASTImporter {
private:
ExternalASTMerger &Parent;
ASTImporter Reverse;
const ExternalASTMerger::OriginMap &FromOrigins;
/// @see ExternalASTMerger::ImporterSource::Temporary
bool TemporarySource;
/// Map of imported declarations back to the declarations they originated
/// from.
llvm::DenseMap<Decl *, Decl *> ToOrigin;
/// @see ExternalASTMerger::ImporterSource::Merger
ExternalASTMerger *SourceMerger;
llvm::raw_ostream &logs() { return Parent.logs(); }
public:
LazyASTImporter(ExternalASTMerger &_Parent, ASTContext &ToContext,
FileManager &ToFileManager,
const ExternalASTMerger::ImporterSource &S,
std::shared_ptr<ASTImporterSharedState> SharedState)
: ASTImporter(ToContext, ToFileManager, S.getASTContext(),
S.getFileManager(),
/*MinimalImport=*/true, SharedState),
Parent(_Parent),
Reverse(S.getASTContext(), S.getFileManager(), ToContext, ToFileManager,
/*MinimalImport=*/true),
FromOrigins(S.getOriginMap()), TemporarySource(S.isTemporary()),
SourceMerger(S.getMerger()) {}
llvm::Expected<Decl *> ImportImpl(Decl *FromD) override {
if (!TemporarySource || !SourceMerger)
return ASTImporter::ImportImpl(FromD);
// If we get here, then this source is importing from a temporary ASTContext
// that also has another ExternalASTMerger attached. It could be
// possible that the current ExternalASTMerger and the temporary ASTContext
// share a common ImporterSource, which means that the temporary
// AST could contain declarations that were imported from a source
// that this ExternalASTMerger can access directly. Instead of importing
// such declarations from the temporary ASTContext, they should instead
// be directly imported by this ExternalASTMerger from the original
// source. This way the ExternalASTMerger can safely do a minimal import
// without creating incomplete declarations originated from a temporary
// ASTContext. If we would try to complete such declarations later on, we
// would fail to do so as their temporary AST could be deleted (which means
// that the missing parts of the minimally imported declaration in that
// ASTContext were also deleted).
//
// The following code tracks back any declaration that needs to be
// imported from the temporary ASTContext to a persistent ASTContext.
// Then the ExternalASTMerger tries to import from the persistent
// ASTContext directly by using the associated ASTImporter. If that
// succeeds, this ASTImporter just maps the declarations imported by
// the other (persistent) ASTImporter to this (temporary) ASTImporter.
// The steps can be visualized like this:
//
// Target AST <--- 3. Indirect import --- Persistent AST
// ^ of persistent decl ^
// | |
// 1. Current import 2. Tracking back to persistent decl
// 4. Map persistent decl |
// & pretend we imported. |
// | |
// Temporary AST -------------------------------'
// First, ask the ExternalASTMerger of the source where the temporary
// declaration originated from.
Decl *Persistent = SourceMerger->FindOriginalDecl(FromD);
// FromD isn't from a persistent AST, so just do a normal import.
if (!Persistent)
return ASTImporter::ImportImpl(FromD);
// Now ask the current ExternalASTMerger to try import the persistent
// declaration into the target.
ASTContext &PersistentCtx = Persistent->getASTContext();
ASTImporter &OtherImporter = Parent.ImporterForOrigin(PersistentCtx);
// Check that we never end up in the current Importer again.
assert((&PersistentCtx != &getFromContext()) && (&OtherImporter != this) &&
"Delegated to same Importer?");
auto DeclOrErr = OtherImporter.Import(Persistent);
// Errors when importing the persistent decl are treated as if we
// had errors with importing the temporary decl.
if (!DeclOrErr)
return DeclOrErr.takeError();
Decl *D = *DeclOrErr;
// Tell the current ASTImporter that this has already been imported
// to prevent any further queries for the temporary decl.
MapImported(FromD, D);
return D;
}
/// Implements the ASTImporter interface for tracking back a declaration
/// to its original declaration it came from.
Decl *GetOriginalDecl(Decl *To) override {
auto It = ToOrigin.find(To);
if (It != ToOrigin.end())
return It->second;
return nullptr;
}
/// Whenever a DeclContext is imported, ensure that ExternalASTSource's origin
/// map is kept up to date. Also set the appropriate flags.
void Imported(Decl *From, Decl *To) override {
ToOrigin[To] = From;
if (auto *ToDC = dyn_cast<DeclContext>(To)) {
const bool LoggingEnabled = Parent.LoggingEnabled();
if (LoggingEnabled)
logs() << "(ExternalASTMerger*)" << (void*)&Parent
<< " imported (DeclContext*)" << (void*)ToDC
<< ", (ASTContext*)" << (void*)&getToContext()
<< " from (DeclContext*)" << (void*)llvm::cast<DeclContext>(From)
<< ", (ASTContext*)" << (void*)&getFromContext()
<< "\n";
Source<DeclContext *> FromDC(
cast<DeclContext>(From)->getPrimaryContext());
if (FromOrigins.count(FromDC) &&
Parent.HasImporterForOrigin(*FromOrigins.at(FromDC).AST)) {
if (LoggingEnabled)
logs() << "(ExternalASTMerger*)" << (void*)&Parent
<< " forced origin (DeclContext*)"
<< (void*)FromOrigins.at(FromDC).DC
<< ", (ASTContext*)"
<< (void*)FromOrigins.at(FromDC).AST
<< "\n";
Parent.ForceRecordOrigin(ToDC, FromOrigins.at(FromDC));
} else {
if (LoggingEnabled)
logs() << "(ExternalASTMerger*)" << (void*)&Parent
<< " maybe recording origin (DeclContext*)" << (void*)FromDC
<< ", (ASTContext*)" << (void*)&getFromContext()
<< "\n";
Parent.MaybeRecordOrigin(ToDC, {FromDC, &getFromContext()});
}
}
if (auto *ToTag = dyn_cast<TagDecl>(To)) {
ToTag->setHasExternalLexicalStorage();
ToTag->getPrimaryContext()->setMustBuildLookupTable();
assert(Parent.CanComplete(ToTag));
} else if (auto *ToNamespace = dyn_cast<NamespaceDecl>(To)) {
ToNamespace->setHasExternalVisibleStorage();
assert(Parent.CanComplete(ToNamespace));
} else if (auto *ToContainer = dyn_cast<ObjCContainerDecl>(To)) {
ToContainer->setHasExternalLexicalStorage();
ToContainer->getPrimaryContext()->setMustBuildLookupTable();
assert(Parent.CanComplete(ToContainer));
}
}
ASTImporter &GetReverse() { return Reverse; }
};
bool HasDeclOfSameType(llvm::ArrayRef<Candidate> Decls, const Candidate &C) {
if (isa<FunctionDecl>(C.first.get()))
return false;
return llvm::any_of(Decls, [&](const Candidate &D) {
return C.first.get()->getKind() == D.first.get()->getKind();
});
}
} // end namespace
ASTImporter &ExternalASTMerger::ImporterForOrigin(ASTContext &OriginContext) {
for (const std::unique_ptr<ASTImporter> &I : Importers)
if (&I->getFromContext() == &OriginContext)
return *I;
llvm_unreachable("We should have an importer for this origin!");
}
namespace {
LazyASTImporter &LazyImporterForOrigin(ExternalASTMerger &Merger,
ASTContext &OriginContext) {
return static_cast<LazyASTImporter &>(
Merger.ImporterForOrigin(OriginContext));
}
}
bool ExternalASTMerger::HasImporterForOrigin(ASTContext &OriginContext) {
for (const std::unique_ptr<ASTImporter> &I : Importers)
if (&I->getFromContext() == &OriginContext)
return true;
return false;
}
template <typename CallbackType>
void ExternalASTMerger::ForEachMatchingDC(const DeclContext *DC,
CallbackType Callback) {
if (Origins.count(DC)) {
ExternalASTMerger::DCOrigin Origin = Origins[DC];
LazyASTImporter &Importer = LazyImporterForOrigin(*this, *Origin.AST);
Callback(Importer, Importer.GetReverse(), Origin.DC);
} else {
bool DidCallback = false;
for (const std::unique_ptr<ASTImporter> &Importer : Importers) {
Source<TranslationUnitDecl *> SourceTU =
Importer->getFromContext().getTranslationUnitDecl();
ASTImporter &Reverse =
static_cast<LazyASTImporter *>(Importer.get())->GetReverse();
if (auto SourceDC = LookupSameContext(SourceTU, DC, Reverse)) {
DidCallback = true;
if (Callback(*Importer, Reverse, SourceDC))
break;
}
}
if (!DidCallback && LoggingEnabled())
logs() << "(ExternalASTMerger*)" << (void*)this
<< " asserting for (DeclContext*)" << (const void*)DC
<< ", (ASTContext*)" << (void*)&Target.AST
<< "\n";
assert(DidCallback && "Couldn't find a source context matching our DC");
}
}
void ExternalASTMerger::CompleteType(TagDecl *Tag) {
assert(Tag->hasExternalLexicalStorage());
ForEachMatchingDC(Tag, [&](ASTImporter &Forward, ASTImporter &Reverse,
Source<const DeclContext *> SourceDC) -> bool {
auto *SourceTag = const_cast<TagDecl *>(cast<TagDecl>(SourceDC.get()));
if (SourceTag->hasExternalLexicalStorage())
SourceTag->getASTContext().getExternalSource()->CompleteType(SourceTag);
if (!SourceTag->getDefinition())
return false;
Forward.MapImported(SourceTag, Tag);
if (llvm::Error Err = Forward.ImportDefinition(SourceTag))
llvm::consumeError(std::move(Err));
Tag->setCompleteDefinition(SourceTag->isCompleteDefinition());
return true;
});
}
void ExternalASTMerger::CompleteType(ObjCInterfaceDecl *Interface) {
assert(Interface->hasExternalLexicalStorage());
ForEachMatchingDC(
Interface, [&](ASTImporter &Forward, ASTImporter &Reverse,
Source<const DeclContext *> SourceDC) -> bool {
auto *SourceInterface = const_cast<ObjCInterfaceDecl *>(
cast<ObjCInterfaceDecl>(SourceDC.get()));
if (SourceInterface->hasExternalLexicalStorage())
SourceInterface->getASTContext().getExternalSource()->CompleteType(
SourceInterface);
if (!SourceInterface->getDefinition())
return false;
Forward.MapImported(SourceInterface, Interface);
if (llvm::Error Err = Forward.ImportDefinition(SourceInterface))
llvm::consumeError(std::move(Err));
return true;
});
}
bool ExternalASTMerger::CanComplete(DeclContext *Interface) {
assert(Interface->hasExternalLexicalStorage() ||
Interface->hasExternalVisibleStorage());
bool FoundMatchingDC = false;
ForEachMatchingDC(Interface,
[&](ASTImporter &Forward, ASTImporter &Reverse,
Source<const DeclContext *> SourceDC) -> bool {
FoundMatchingDC = true;
return true;
});
return FoundMatchingDC;
}
namespace {
bool IsSameDC(const DeclContext *D1, const DeclContext *D2) {
if (isa<ObjCContainerDecl>(D1) && isa<ObjCContainerDecl>(D2))
return true; // There are many cases where Objective-C is ambiguous.
if (auto *T1 = dyn_cast<TagDecl>(D1))
if (auto *T2 = dyn_cast<TagDecl>(D2))
if (T1->getFirstDecl() == T2->getFirstDecl())
return true;
return D1 == D2 || D1 == CanonicalizeDC(D2);
}
}
void ExternalASTMerger::MaybeRecordOrigin(const DeclContext *ToDC,
DCOrigin Origin) {
LazyASTImporter &Importer = LazyImporterForOrigin(*this, *Origin.AST);
ASTImporter &Reverse = Importer.GetReverse();
Source<const DeclContext *> FoundFromDC =
LookupSameContext(Origin.AST->getTranslationUnitDecl(), ToDC, Reverse);
const bool DoRecord = !FoundFromDC || !IsSameDC(FoundFromDC.get(), Origin.DC);
if (DoRecord)
RecordOriginImpl(ToDC, Origin, Importer);
if (LoggingEnabled())
logs() << "(ExternalASTMerger*)" << (void*)this
<< (DoRecord ? " decided " : " decided NOT")
<< " to record origin (DeclContext*)" << (void*)Origin.DC
<< ", (ASTContext*)" << (void*)&Origin.AST
<< "\n";
}
void ExternalASTMerger::ForceRecordOrigin(const DeclContext *ToDC,
DCOrigin Origin) {
RecordOriginImpl(ToDC, Origin, ImporterForOrigin(*Origin.AST));
}
void ExternalASTMerger::RecordOriginImpl(const DeclContext *ToDC, DCOrigin Origin,
ASTImporter &Importer) {
Origins[ToDC] = Origin;
Importer.ASTImporter::MapImported(cast<Decl>(Origin.DC), const_cast<Decl*>(cast<Decl>(ToDC)));
}
ExternalASTMerger::ExternalASTMerger(const ImporterTarget &Target,
llvm::ArrayRef<ImporterSource> Sources) : LogStream(&llvm::nulls()), Target(Target) {
SharedState = std::make_shared<ASTImporterSharedState>(
*Target.AST.getTranslationUnitDecl());
AddSources(Sources);
}
Decl *ExternalASTMerger::FindOriginalDecl(Decl *D) {
assert(&D->getASTContext() == &Target.AST);
for (const auto &I : Importers)
if (auto Result = I->GetOriginalDecl(D))
return Result;
return nullptr;
}
void ExternalASTMerger::AddSources(llvm::ArrayRef<ImporterSource> Sources) {
for (const ImporterSource &S : Sources) {
assert(&S.getASTContext() != &Target.AST);
// Check that the associated merger actually imports into the source AST.
assert(!S.getMerger() || &S.getMerger()->Target.AST == &S.getASTContext());
Importers.push_back(std::make_unique<LazyASTImporter>(
*this, Target.AST, Target.FM, S, SharedState));
}
}
void ExternalASTMerger::RemoveSources(llvm::ArrayRef<ImporterSource> Sources) {
if (LoggingEnabled())
for (const ImporterSource &S : Sources)
logs() << "(ExternalASTMerger*)" << (void *)this
<< " removing source (ASTContext*)" << (void *)&S.getASTContext()
<< "\n";
Importers.erase(
std::remove_if(Importers.begin(), Importers.end(),
[&Sources](std::unique_ptr<ASTImporter> &Importer) -> bool {
for (const ImporterSource &S : Sources) {
if (&Importer->getFromContext() == &S.getASTContext())
return true;
}
return false;
}),
Importers.end());
for (OriginMap::iterator OI = Origins.begin(), OE = Origins.end(); OI != OE; ) {
std::pair<const DeclContext *, DCOrigin> Origin = *OI;
bool Erase = false;
for (const ImporterSource &S : Sources) {
if (&S.getASTContext() == Origin.second.AST) {
Erase = true;
break;
}
}
if (Erase)
OI = Origins.erase(OI);
else
++OI;
}
}
template <typename DeclTy>
static bool importSpecializations(DeclTy *D, ASTImporter *Importer) {
for (auto *Spec : D->specializations()) {
auto ImportedSpecOrError = Importer->Import(Spec);
if (!ImportedSpecOrError) {
llvm::consumeError(ImportedSpecOrError.takeError());
return true;
}
}
return false;
}
/// Imports specializations from template declarations that can be specialized.
static bool importSpecializationsIfNeeded(Decl *D, ASTImporter *Importer) {
if (!isa<TemplateDecl>(D))
return false;
if (auto *FunctionTD = dyn_cast<FunctionTemplateDecl>(D))
return importSpecializations(FunctionTD, Importer);
else if (auto *ClassTD = dyn_cast<ClassTemplateDecl>(D))
return importSpecializations(ClassTD, Importer);
else if (auto *VarTD = dyn_cast<VarTemplateDecl>(D))
return importSpecializations(VarTD, Importer);
return false;
}
bool ExternalASTMerger::FindExternalVisibleDeclsByName(const DeclContext *DC,
DeclarationName Name) {
llvm::SmallVector<NamedDecl *, 1> Decls;
llvm::SmallVector<Candidate, 4> Candidates;
auto FilterFoundDecl = [&Candidates](const Candidate &C) {
if (!HasDeclOfSameType(Candidates, C))
Candidates.push_back(C);
};
ForEachMatchingDC(DC,
[&](ASTImporter &Forward, ASTImporter &Reverse,
Source<const DeclContext *> SourceDC) -> bool {
auto FromNameOrErr = Reverse.Import(Name);
if (!FromNameOrErr) {
llvm::consumeError(FromNameOrErr.takeError());
return false;
}
DeclContextLookupResult Result =
SourceDC.get()->lookup(*FromNameOrErr);
for (NamedDecl *FromD : Result) {
FilterFoundDecl(std::make_pair(FromD, &Forward));
}
return false;
});
if (Candidates.empty())
return false;
Decls.reserve(Candidates.size());
for (const Candidate &C : Candidates) {
Decl *LookupRes = C.first.get();
ASTImporter *Importer = C.second;
auto NDOrErr = Importer->Import(LookupRes);
NamedDecl *ND = cast<NamedDecl>(llvm::cantFail(std::move(NDOrErr)));
assert(ND);
// If we don't import specialization, they are not available via lookup
// because the lookup result is imported TemplateDecl and it does not
// reference its specializations until they are imported explicitly.
bool IsSpecImportFailed =
importSpecializationsIfNeeded(LookupRes, Importer);
assert(!IsSpecImportFailed);
(void)IsSpecImportFailed;
Decls.push_back(ND);
}
SetExternalVisibleDeclsForName(DC, Name, Decls);
return true;
}
void ExternalASTMerger::FindExternalLexicalDecls(
const DeclContext *DC, llvm::function_ref<bool(Decl::Kind)> IsKindWeWant,
SmallVectorImpl<Decl *> &Result) {
ForEachMatchingDC(DC, [&](ASTImporter &Forward, ASTImporter &Reverse,
Source<const DeclContext *> SourceDC) -> bool {
for (const Decl *SourceDecl : SourceDC.get()->decls()) {
if (IsKindWeWant(SourceDecl->getKind())) {
auto ImportedDeclOrErr = Forward.Import(SourceDecl);
if (ImportedDeclOrErr)
assert(!(*ImportedDeclOrErr) ||
IsSameDC((*ImportedDeclOrErr)->getDeclContext(), DC));
else
llvm::consumeError(ImportedDeclOrErr.takeError());
}
}
return false;
});
}
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