Emit standard-library RTTI with external linkage, not weak_odr.
Apply hidden visibility to most RTTI; libstdc++ does not rely on exact
pointer equality for the type info (just the type info names). Apply
the same optimization to RTTI that we do to vtables.
Fixes PR5962.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@110192 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGRTTI.cpp b/lib/CodeGen/CGRTTI.cpp
index 1cca977..0724fdf 100644
--- a/lib/CodeGen/CGRTTI.cpp
+++ b/lib/CodeGen/CGRTTI.cpp
@@ -244,11 +244,9 @@
return TypeInfoIsInStandardLibrary(BuiltinTy);
}
-/// ShouldUseExternalRTTIDescriptor - Returns whether the type information for
-/// the given type exists somewhere else, and that we should not emit the type
-/// information in this translation unit.
-static bool ShouldUseExternalRTTIDescriptor(ASTContext &Context,
- QualType Ty) {
+/// IsStandardLibraryRTTIDescriptor - Returns whether the type
+/// information for the given type exists in the standard library.
+static bool IsStandardLibraryRTTIDescriptor(QualType Ty) {
// Type info for builtin types is defined in the standard library.
if (const BuiltinType *BuiltinTy = dyn_cast<BuiltinType>(Ty))
return TypeInfoIsInStandardLibrary(BuiltinTy);
@@ -258,6 +256,15 @@
if (const PointerType *PointerTy = dyn_cast<PointerType>(Ty))
return TypeInfoIsInStandardLibrary(PointerTy);
+ return false;
+}
+
+/// ShouldUseExternalRTTIDescriptor - Returns whether the type information for
+/// the given type exists somewhere else, and that we should not emit the type
+/// information in this translation unit. Assumes that it is not a
+/// standard-library type.
+static bool ShouldUseExternalRTTIDescriptor(ASTContext &Context,
+ QualType Ty) {
// If RTTI is disabled, don't consider key functions.
if (!Context.getLangOptions().RTTI) return false;
@@ -456,8 +463,7 @@
Fields.push_back(VTable);
}
-llvm::Constant *RTTIBuilder::BuildTypeInfo(QualType Ty,
- bool Force) {
+llvm::Constant *RTTIBuilder::BuildTypeInfo(QualType Ty, bool Force) {
// We want to operate on the canonical type.
Ty = CGM.getContext().getCanonicalType(Ty);
@@ -469,19 +475,26 @@
llvm::GlobalVariable *OldGV = CGM.getModule().getNamedGlobal(Name);
if (OldGV && !OldGV->isDeclaration())
return llvm::ConstantExpr::getBitCast(OldGV, Int8PtrTy);
-
+
// Check if there is already an external RTTI descriptor for this type.
- if (!Force && ShouldUseExternalRTTIDescriptor(CGM.getContext(), Ty))
+ bool IsStdLib = IsStandardLibraryRTTIDescriptor(Ty);
+ if (!Force &&
+ (IsStdLib || ShouldUseExternalRTTIDescriptor(CGM.getContext(), Ty)))
return GetAddrOfExternalRTTIDescriptor(Ty);
- llvm::GlobalVariable::LinkageTypes Linkage = getTypeInfoLinkage(Ty);
+ // Emit the standard library with external linkage.
+ llvm::GlobalVariable::LinkageTypes Linkage;
+ if (IsStdLib)
+ Linkage = llvm::GlobalValue::ExternalLinkage;
+ else
+ Linkage = getTypeInfoLinkage(Ty);
// Add the vtable pointer.
BuildVTablePointer(cast<Type>(Ty));
// And the name.
Fields.push_back(BuildName(Ty, DecideHidden(Ty), Linkage));
-
+
switch (Ty->getTypeClass()) {
default: assert(false && "Unhandled type class!");
@@ -551,7 +564,15 @@
OldGV->replaceAllUsesWith(NewPtr);
OldGV->eraseFromParent();
}
-
+
+ // GCC only relies on the uniqueness of the type names, not the
+ // type_infos themselves, so we can emit these as hidden symbols.
+ if (const RecordType *RT = dyn_cast<RecordType>(Ty))
+ CGM.setTypeVisibility(GV, cast<CXXRecordDecl>(RT->getDecl()),
+ /*ForRTTI*/ true);
+ else if (Linkage == llvm::GlobalValue::WeakODRLinkage)
+ GV->setVisibility(llvm::GlobalValue::HiddenVisibility);
+
return llvm::ConstantExpr::getBitCast(GV, Int8PtrTy);
}