[modules] Don't emit initializers for VarDecls within a module eagerly whenever
we first touch any part of that module. Instead, defer them until the first
time that module is (transitively) imported. The initializer step for a module
then recursively initializes modules that its own headers imported.
For example, this avoids running the <iostream> global initializer in programs
that don't actually use iostreams, but do use other parts of the standard
library.
llvm-svn: 276159
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index e54c88f..fadcda0 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -901,6 +901,67 @@
Merged.erase(std::remove(Merged.begin(), Merged.end(), nullptr), Merged.end());
}
+void ASTContext::PerModuleInitializers::resolve(ASTContext &Ctx) {
+ if (LazyInitializers.empty())
+ return;
+
+ auto *Source = Ctx.getExternalSource();
+ assert(Source && "lazy initializers but no external source");
+
+ auto LazyInits = std::move(LazyInitializers);
+ LazyInitializers.clear();
+
+ for (auto ID : LazyInits)
+ Initializers.push_back(Source->GetExternalDecl(ID));
+
+ assert(LazyInitializers.empty() &&
+ "GetExternalDecl for lazy module initializer added more inits");
+}
+
+void ASTContext::addModuleInitializer(Module *M, Decl *D) {
+ // One special case: if we add a module initializer that imports another
+ // module, and that module's only initializer is an ImportDecl, simplify.
+ if (auto *ID = dyn_cast<ImportDecl>(D)) {
+ auto It = ModuleInitializers.find(ID->getImportedModule());
+
+ // Maybe the ImportDecl does nothing at all. (Common case.)
+ if (It == ModuleInitializers.end())
+ return;
+
+ // Maybe the ImportDecl only imports another ImportDecl.
+ auto &Imported = *It->second;
+ if (Imported.Initializers.size() + Imported.LazyInitializers.size() == 1) {
+ Imported.resolve(*this);
+ auto *OnlyDecl = Imported.Initializers.front();
+ if (isa<ImportDecl>(OnlyDecl))
+ D = OnlyDecl;
+ }
+ }
+
+ auto *&Inits = ModuleInitializers[M];
+ if (!Inits)
+ Inits = new (*this) PerModuleInitializers;
+ Inits->Initializers.push_back(D);
+}
+
+void ASTContext::addLazyModuleInitializers(Module *M, ArrayRef<uint32_t> IDs) {
+ auto *&Inits = ModuleInitializers[M];
+ if (!Inits)
+ Inits = new (*this) PerModuleInitializers;
+ Inits->LazyInitializers.insert(Inits->LazyInitializers.end(),
+ IDs.begin(), IDs.end());
+}
+
+ArrayRef<Decl*> ASTContext::getModuleInitializers(Module *M) {
+ auto It = ModuleInitializers.find(M);
+ if (It == ModuleInitializers.end())
+ return None;
+
+ auto *Inits = It->second;
+ Inits->resolve(*this);
+ return Inits->Initializers;
+}
+
ExternCContextDecl *ASTContext::getExternCContextDecl() const {
if (!ExternCContext)
ExternCContext = ExternCContextDecl::Create(*this, getTranslationUnitDecl());
@@ -8575,6 +8636,8 @@
return !D->getDeclContext()->isDependentContext();
else if (isa<OMPDeclareReductionDecl>(D))
return !D->getDeclContext()->isDependentContext();
+ else if (isa<ImportDecl>(D))
+ return true;
else
return false;