1 //===- ExternalASTMerger.cpp - Merging External AST Interface ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the ExternalASTMerger, which vends a combination of
11 // ASTs from several different ASTContext/FileManager pairs
13 //===----------------------------------------------------------------------===//
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/Decl.h"
17 #include "clang/AST/DeclCXX.h"
18 #include "clang/AST/DeclObjC.h"
19 #include "clang/AST/ExternalASTMerger.h"
21 using namespace clang;
25 template <typename T> struct Source {
28 operator T() { return t; }
29 template <typename U = T> U &get() { return t; }
30 template <typename U = T> const U &get() const { return t; }
31 template <typename U> operator Source<U>() { return Source<U>(t); }
34 typedef std::pair<Source<NamedDecl *>, ASTImporter *> Candidate;
36 /// For the given DC, return the DC that is safe to perform lookups on. This is
37 /// the DC we actually want to work with most of the time.
38 const DeclContext *CanonicalizeDC(const DeclContext *DC) {
39 if (isa<LinkageSpecDecl>(DC))
40 return DC->getRedeclContext();
44 Source<const DeclContext *>
45 LookupSameContext(Source<TranslationUnitDecl *> SourceTU, const DeclContext *DC,
46 ASTImporter &ReverseImporter) {
47 DC = CanonicalizeDC(DC);
48 if (DC->isTranslationUnit()) {
51 Source<const DeclContext *> SourceParentDC =
52 LookupSameContext(SourceTU, DC->getParent(), ReverseImporter);
53 if (!SourceParentDC) {
54 // If we couldn't find the parent DC in this TranslationUnit, give up.
57 auto *ND = cast<NamedDecl>(DC);
58 DeclarationName Name = ND->getDeclName();
59 Source<DeclarationName> SourceName = ReverseImporter.Import(Name);
60 DeclContext::lookup_result SearchResult =
61 SourceParentDC.get()->lookup(SourceName.get());
62 size_t SearchResultSize = SearchResult.size();
63 if (SearchResultSize == 0 || SearchResultSize > 1) {
64 // There are two cases here. First, we might not find the name.
65 // We might also find multiple copies, in which case we have no
66 // guarantee that the one we wanted is the one we pick. (E.g.,
67 // if we have two specializations of the same template it is
68 // very hard to determine which is the one you want.)
70 // The Origins map fixes this problem by allowing the origin to be
71 // explicitly recorded, so we trigger that recording by returning
72 // nothing (rather than a possibly-inaccurate guess) here.
75 NamedDecl *SearchResultDecl = SearchResult[0];
76 if (isa<DeclContext>(SearchResultDecl) &&
77 SearchResultDecl->getKind() == DC->getDeclKind())
78 return cast<DeclContext>(SearchResultDecl)->getPrimaryContext();
79 return nullptr; // This type of lookup is unsupported
83 /// A custom implementation of ASTImporter, for ExternalASTMerger's purposes.
85 /// There are several modifications:
87 /// - It enables lazy lookup (via the HasExternalLexicalStorage flag and a few
88 /// others), which instructs Clang to refer to ExternalASTMerger. Also, it
89 /// forces MinimalImport to true, which is necessary to make this work.
90 /// - It maintains a reverse importer for use with names. This allows lookup of
91 /// arbitrary names in the source context.
92 /// - It updates the ExternalASTMerger's origin map as needed whenever a
93 /// it sees a DeclContext.
94 class LazyASTImporter : public ASTImporter {
96 ExternalASTMerger &Parent;
98 const ExternalASTMerger::OriginMap &FromOrigins;
100 llvm::raw_ostream &logs() { return Parent.logs(); }
102 LazyASTImporter(ExternalASTMerger &_Parent, ASTContext &ToContext,
103 FileManager &ToFileManager, ASTContext &FromContext,
104 FileManager &FromFileManager,
105 const ExternalASTMerger::OriginMap &_FromOrigins)
106 : ASTImporter(ToContext, ToFileManager, FromContext, FromFileManager,
107 /*MinimalImport=*/true),
108 Parent(_Parent), Reverse(FromContext, FromFileManager, ToContext,
109 ToFileManager, /*MinimalImport=*/true), FromOrigins(_FromOrigins) {}
111 /// Whenever a DeclContext is imported, ensure that ExternalASTSource's origin
112 /// map is kept up to date. Also set the appropriate flags.
113 Decl *Imported(Decl *From, Decl *To) override {
114 if (auto *ToDC = dyn_cast<DeclContext>(To)) {
115 const bool LoggingEnabled = Parent.LoggingEnabled();
117 logs() << "(ExternalASTMerger*)" << (void*)&Parent
118 << " imported (DeclContext*)" << (void*)ToDC
119 << ", (ASTContext*)" << (void*)&getToContext()
120 << " from (DeclContext*)" << (void*)llvm::cast<DeclContext>(From)
121 << ", (ASTContext*)" << (void*)&getFromContext()
123 Source<DeclContext *> FromDC(
124 cast<DeclContext>(From)->getPrimaryContext());
125 if (FromOrigins.count(FromDC) &&
126 Parent.HasImporterForOrigin(*FromOrigins.at(FromDC).AST)) {
128 logs() << "(ExternalASTMerger*)" << (void*)&Parent
129 << " forced origin (DeclContext*)"
130 << (void*)FromOrigins.at(FromDC).DC
132 << (void*)FromOrigins.at(FromDC).AST
134 Parent.ForceRecordOrigin(ToDC, FromOrigins.at(FromDC));
137 logs() << "(ExternalASTMerger*)" << (void*)&Parent
138 << " maybe recording origin (DeclContext*)" << (void*)FromDC
139 << ", (ASTContext*)" << (void*)&getFromContext()
141 Parent.MaybeRecordOrigin(ToDC, {FromDC, &getFromContext()});
144 if (auto *ToTag = dyn_cast<TagDecl>(To)) {
145 ToTag->setHasExternalLexicalStorage();
146 ToTag->setMustBuildLookupTable();
147 assert(Parent.CanComplete(ToTag));
148 } else if (auto *ToNamespace = dyn_cast<NamespaceDecl>(To)) {
149 ToNamespace->setHasExternalVisibleStorage();
150 assert(Parent.CanComplete(ToNamespace));
151 } else if (auto *ToContainer = dyn_cast<ObjCContainerDecl>(To)) {
152 ToContainer->setHasExternalLexicalStorage();
153 ToContainer->setMustBuildLookupTable();
154 assert(Parent.CanComplete(ToContainer));
156 return ASTImporter::Imported(From, To);
158 ASTImporter &GetReverse() { return Reverse; }
161 bool HasDeclOfSameType(llvm::ArrayRef<Candidate> Decls, const Candidate &C) {
162 if (isa<FunctionDecl>(C.first.get()))
164 return llvm::any_of(Decls, [&](const Candidate &D) {
165 return C.first.get()->getKind() == D.first.get()->getKind();
171 ASTImporter &ExternalASTMerger::ImporterForOrigin(ASTContext &OriginContext) {
172 for (const std::unique_ptr<ASTImporter> &I : Importers)
173 if (&I->getFromContext() == &OriginContext)
175 llvm_unreachable("We should have an importer for this origin!");
179 LazyASTImporter &LazyImporterForOrigin(ExternalASTMerger &Merger,
180 ASTContext &OriginContext) {
181 return static_cast<LazyASTImporter &>(
182 Merger.ImporterForOrigin(OriginContext));
186 bool ExternalASTMerger::HasImporterForOrigin(ASTContext &OriginContext) {
187 for (const std::unique_ptr<ASTImporter> &I : Importers)
188 if (&I->getFromContext() == &OriginContext)
193 template <typename CallbackType>
194 void ExternalASTMerger::ForEachMatchingDC(const DeclContext *DC,
195 CallbackType Callback) {
196 if (Origins.count(DC)) {
197 ExternalASTMerger::DCOrigin Origin = Origins[DC];
198 LazyASTImporter &Importer = LazyImporterForOrigin(*this, *Origin.AST);
199 Callback(Importer, Importer.GetReverse(), Origin.DC);
201 bool DidCallback = false;
202 for (const std::unique_ptr<ASTImporter> &Importer : Importers) {
203 Source<TranslationUnitDecl *> SourceTU =
204 Importer->getFromContext().getTranslationUnitDecl();
205 ASTImporter &Reverse =
206 static_cast<LazyASTImporter *>(Importer.get())->GetReverse();
207 if (auto SourceDC = LookupSameContext(SourceTU, DC, Reverse)) {
209 if (Callback(*Importer, Reverse, SourceDC))
213 if (!DidCallback && LoggingEnabled())
214 logs() << "(ExternalASTMerger*)" << (void*)this
215 << " asserting for (DeclContext*)" << (const void*)DC
216 << ", (ASTContext*)" << (void*)&Target.AST
218 assert(DidCallback && "Couldn't find a source context matching our DC");
222 void ExternalASTMerger::CompleteType(TagDecl *Tag) {
223 assert(Tag->hasExternalLexicalStorage());
224 ForEachMatchingDC(Tag, [&](ASTImporter &Forward, ASTImporter &Reverse,
225 Source<const DeclContext *> SourceDC) -> bool {
226 auto *SourceTag = const_cast<TagDecl *>(cast<TagDecl>(SourceDC.get()));
227 if (SourceTag->hasExternalLexicalStorage())
228 SourceTag->getASTContext().getExternalSource()->CompleteType(SourceTag);
229 if (!SourceTag->getDefinition())
231 Forward.Imported(SourceTag, Tag);
232 Forward.ImportDefinition(SourceTag);
233 Tag->setCompleteDefinition(SourceTag->isCompleteDefinition());
238 void ExternalASTMerger::CompleteType(ObjCInterfaceDecl *Interface) {
239 assert(Interface->hasExternalLexicalStorage());
241 Interface, [&](ASTImporter &Forward, ASTImporter &Reverse,
242 Source<const DeclContext *> SourceDC) -> bool {
243 auto *SourceInterface = const_cast<ObjCInterfaceDecl *>(
244 cast<ObjCInterfaceDecl>(SourceDC.get()));
245 if (SourceInterface->hasExternalLexicalStorage())
246 SourceInterface->getASTContext().getExternalSource()->CompleteType(
248 if (!SourceInterface->getDefinition())
250 Forward.Imported(SourceInterface, Interface);
251 Forward.ImportDefinition(SourceInterface);
256 bool ExternalASTMerger::CanComplete(DeclContext *Interface) {
257 assert(Interface->hasExternalLexicalStorage() ||
258 Interface->hasExternalVisibleStorage());
259 bool FoundMatchingDC = false;
260 ForEachMatchingDC(Interface,
261 [&](ASTImporter &Forward, ASTImporter &Reverse,
262 Source<const DeclContext *> SourceDC) -> bool {
263 FoundMatchingDC = true;
266 return FoundMatchingDC;
270 bool IsSameDC(const DeclContext *D1, const DeclContext *D2) {
271 if (isa<ObjCContainerDecl>(D1) && isa<ObjCContainerDecl>(D2))
272 return true; // There are many cases where Objective-C is ambiguous.
273 if (auto *T1 = dyn_cast<TagDecl>(D1))
274 if (auto *T2 = dyn_cast<TagDecl>(D2))
275 if (T1->getFirstDecl() == T2->getFirstDecl())
277 return D1 == D2 || D1 == CanonicalizeDC(D2);
281 void ExternalASTMerger::MaybeRecordOrigin(const DeclContext *ToDC,
283 LazyASTImporter &Importer = LazyImporterForOrigin(*this, *Origin.AST);
284 ASTImporter &Reverse = Importer.GetReverse();
285 Source<const DeclContext *> FoundFromDC =
286 LookupSameContext(Origin.AST->getTranslationUnitDecl(), ToDC, Reverse);
287 const bool DoRecord = !FoundFromDC || !IsSameDC(FoundFromDC.get(), Origin.DC);
289 RecordOriginImpl(ToDC, Origin, Importer);
290 if (LoggingEnabled())
291 logs() << "(ExternalASTMerger*)" << (void*)this
292 << (DoRecord ? " decided " : " decided NOT")
293 << " to record origin (DeclContext*)" << (void*)Origin.DC
294 << ", (ASTContext*)" << (void*)&Origin.AST
298 void ExternalASTMerger::ForceRecordOrigin(const DeclContext *ToDC,
300 RecordOriginImpl(ToDC, Origin, ImporterForOrigin(*Origin.AST));
303 void ExternalASTMerger::RecordOriginImpl(const DeclContext *ToDC, DCOrigin Origin,
304 ASTImporter &Importer) {
305 Origins[ToDC] = Origin;
306 Importer.ASTImporter::Imported(cast<Decl>(Origin.DC), const_cast<Decl*>(cast<Decl>(ToDC)));
309 ExternalASTMerger::ExternalASTMerger(const ImporterTarget &Target,
310 llvm::ArrayRef<ImporterSource> Sources) : LogStream(&llvm::nulls()), Target(Target) {
314 void ExternalASTMerger::AddSources(llvm::ArrayRef<ImporterSource> Sources) {
315 for (const ImporterSource &S : Sources) {
316 assert(&S.AST != &Target.AST);
317 Importers.push_back(llvm::make_unique<LazyASTImporter>(
318 *this, Target.AST, Target.FM, S.AST, S.FM, S.OM));
322 void ExternalASTMerger::RemoveSources(llvm::ArrayRef<ImporterSource> Sources) {
323 if (LoggingEnabled())
324 for (const ImporterSource &S : Sources)
325 logs() << "(ExternalASTMerger*)" << (void*)this
326 << " removing source (ASTContext*)" << (void*)&S.AST
329 std::remove_if(Importers.begin(), Importers.end(),
330 [&Sources](std::unique_ptr<ASTImporter> &Importer) -> bool {
331 for (const ImporterSource &S : Sources) {
332 if (&Importer->getFromContext() == &S.AST)
338 for (OriginMap::iterator OI = Origins.begin(), OE = Origins.end(); OI != OE; ) {
339 std::pair<const DeclContext *, DCOrigin> Origin = *OI;
341 for (const ImporterSource &S : Sources) {
342 if (&S.AST == Origin.second.AST) {
348 OI = Origins.erase(OI);
354 bool ExternalASTMerger::FindExternalVisibleDeclsByName(const DeclContext *DC,
355 DeclarationName Name) {
356 llvm::SmallVector<NamedDecl *, 1> Decls;
357 llvm::SmallVector<Candidate, 4> Candidates;
359 auto FilterFoundDecl = [&Candidates](const Candidate &C) {
360 if (!HasDeclOfSameType(Candidates, C))
361 Candidates.push_back(C);
364 ForEachMatchingDC(DC, [&](ASTImporter &Forward, ASTImporter &Reverse,
365 Source<const DeclContext *> SourceDC) -> bool {
366 DeclarationName FromName = Reverse.Import(Name);
367 DeclContextLookupResult Result = SourceDC.get()->lookup(FromName);
368 for (NamedDecl *FromD : Result) {
369 FilterFoundDecl(std::make_pair(FromD, &Forward));
374 if (Candidates.empty())
377 Decls.reserve(Candidates.size());
378 for (const Candidate &C : Candidates) {
379 NamedDecl *d = cast<NamedDecl>(C.second->Import(C.first.get()));
383 SetExternalVisibleDeclsForName(DC, Name, Decls);
387 void ExternalASTMerger::FindExternalLexicalDecls(
388 const DeclContext *DC, llvm::function_ref<bool(Decl::Kind)> IsKindWeWant,
389 SmallVectorImpl<Decl *> &Result) {
390 ForEachMatchingDC(DC, [&](ASTImporter &Forward, ASTImporter &Reverse,
391 Source<const DeclContext *> SourceDC) -> bool {
392 for (const Decl *SourceDecl : SourceDC.get()->decls()) {
393 if (IsKindWeWant(SourceDecl->getKind())) {
394 Decl *ImportedDecl = Forward.Import(const_cast<Decl *>(SourceDecl));
395 assert(!ImportedDecl || IsSameDC(ImportedDecl->getDeclContext(), DC));