Eliminate excessive PCH deserialization caused by the search for
__cxxabiv1::__fundamental_type_info in every translation
unit. Previously, we would perform name lookup for
__cxxabiv1::__fundamental_type_info at the end of IRGen for a each
translation unit, to determine whether it was present. If so, we we
produce type information for all of the fundamental types. However,
this name lookup causes PCH deserialization of a significant part of the
translation unit, which has a woeful impact on performance.
With this change, we now look at each record type after we've
generated its vtable to see if it is
__cxxabiv1::__fundamental_type_info. If so, we generate type info for
all of the fundamental types. This works because
__cxxabiv1::__fundamental_type_info should always have a key function
(typically the virtual destructor), that will be defined once in the
support library. The fundamental type information will end up there.
Fixes <rdar://problem/7840011>.
llvm-svn: 100772
diff --git a/clang/lib/CodeGen/CGVtable.cpp b/clang/lib/CodeGen/CGVtable.cpp
index fc6d1a8..e23289a 100644
--- a/clang/lib/CodeGen/CGVtable.cpp
+++ b/clang/lib/CodeGen/CGVtable.cpp
@@ -3121,6 +3121,18 @@
EmitVTableDefinition(VTable, Linkage, RD);
GenerateVTT(Linkage, /*GenerateDefinition=*/true, RD);
+
+ // If this is the magic class __cxxabiv1::__fundamental_type_info,
+ // we will emit the typeinfo for the fundamental types. This is the
+ // same behaviour as GCC.
+ const DeclContext *DC = RD->getDeclContext();
+ if (RD->getIdentifier() &&
+ RD->getIdentifier()->isStr("__fundamental_type_info") &&
+ isa<NamespaceDecl>(DC) &&
+ cast<NamespaceDecl>(DC)->getIdentifier() &&
+ cast<NamespaceDecl>(DC)->getIdentifier()->isStr("__cxxabiv1") &&
+ DC->getParent()->isTranslationUnit())
+ CGM.EmitFundamentalRTTIDescriptors();
}
void CodeGenVTables::EmitVTableRelatedData(GlobalDecl GD) {