Introduce a fast path for the ASTReader's name lookup within a
DeclContext. When the DeclContext is of a kind that can only be
defined once and never updated, we limit the search to the module file
that conatins the lookup table. Provides a 15% speedup in one
modules-heavy source file.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173050 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 00bae0a..db850f3 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -4971,7 +4971,7 @@
return &M == I->second;
}
-ModuleFile *ASTReader::getOwningModuleFile(Decl *D) {
+ModuleFile *ASTReader::getOwningModuleFile(const Decl *D) {
if (!D->isFromASTFile())
return 0;
GlobalDeclMapType::const_iterator I = GlobalDeclMap.find(D->getGlobalID());
@@ -5307,6 +5307,27 @@
};
}
+/// \brief Retrieve the "definitive" module file for the definition of the
+/// given declaration context, if there is one.
+///
+/// The "definitive" module file is the only place where we need to look to
+/// find information about the declarations within the given declaration
+/// context. For example, C++ and Objective-C classes, C structs/unions, and
+/// Objective-C protocols, categories, and extensions are all defined in a
+/// single place in the source code, so they have definitive module files
+/// associated with them. C++ namespaces, on the other hand, can have
+/// definitions in multiple different module files.
+///
+/// Note: this needs to be kept in sync with ASTWriter::AddedVisibleDecl's
+/// NDEBUG checking.
+static ModuleFile *getDefinitiveModuleFileFor(const DeclContext *DC,
+ ASTReader &Reader) {
+ if (const Decl *D = getDefinitiveDeclContext(DC))
+ return Reader.getOwningModuleFile(D);
+
+ return 0;
+}
+
DeclContext::lookup_result
ASTReader::FindExternalVisibleDeclsByName(const DeclContext *DC,
DeclarationName Name) {
@@ -5335,7 +5356,16 @@
}
DeclContextNameLookupVisitor Visitor(*this, Contexts, Name, Decls);
- ModuleMgr.visit(&DeclContextNameLookupVisitor::visit, &Visitor);
+
+ // If we can definitively determine which module file to look into,
+ // only look there. Otherwise, look in all module files.
+ ModuleFile *Definitive;
+ if (Contexts.size() == 1 &&
+ (Definitive = getDefinitiveModuleFileFor(DC, *this))) {
+ DeclContextNameLookupVisitor::visit(*Definitive, &Visitor);
+ } else {
+ ModuleMgr.visit(&DeclContextNameLookupVisitor::visit, &Visitor);
+ }
++NumVisibleDeclContextsRead;
SetExternalVisibleDeclsForName(DC, Name, Decls);
return const_cast<DeclContext*>(DC)->lookup(Name);