Extend the visibility-hidden optimization to linkonce_odr thunks for
functions with in-line definitions, since such thunks will be emitted at any
use of the function.
Completes the feature work for rdar://problem/7523229.
llvm-svn: 110285
diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index db405d3..cd34d03 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -2460,6 +2460,56 @@
return CGF.Builder.CreateBitCast(V, Ptr->getType());
}
+static void setThunkVisibility(CodeGenModule &CGM, const CXXMethodDecl *MD,
+ const ThunkInfo &Thunk, llvm::Function *Fn) {
+ CGM.setGlobalVisibility(Fn, MD);
+
+ // If the thunk has weak/linkonce linkage, but the function must be
+ // emitted in every translation unit that references it, then we can
+ // emit its thunks with hidden visibility, since its thunks must be
+ // emitted when the function is.
+
+ // This mostly follows CodeGenModule::setTypeVisibility.
+
+ if ((Fn->getLinkage() != llvm::GlobalVariable::LinkOnceODRLinkage &&
+ Fn->getLinkage() != llvm::GlobalVariable::WeakODRLinkage) ||
+ Fn->getVisibility() != llvm::GlobalVariable::DefaultVisibility)
+ return;
+
+ // Don't override an explicit visibility attribute.
+ if (MD->hasAttr<VisibilityAttr>())
+ return;
+
+ switch (MD->getTemplateSpecializationKind()) {
+ // We have to disable the optimization if this is an EI definition
+ // because there might be EI declarations in other shared objects.
+ case TSK_ExplicitInstantiationDefinition:
+ case TSK_ExplicitInstantiationDeclaration:
+ return;
+
+ // Every use of a non-template or explicitly-specialized class's
+ // type information has to emit it.
+ case TSK_ExplicitSpecialization:
+ case TSK_Undeclared:
+ break;
+
+ // Implicit instantiations can ignore the possibility of an
+ // explicit instantiation declaration because there necessarily
+ // must be an EI definition somewhere with default visibility.
+ case TSK_ImplicitInstantiation:
+ break;
+ }
+
+ // If there's an explicit definition, and that definition is
+ // out-of-line, then we can't assume that all users will have a
+ // definition to emit.
+ const FunctionDecl *Def = 0;
+ if (MD->hasBody(Def) && Def->isOutOfLine())
+ return;
+
+ Fn->setVisibility(llvm::GlobalValue::HiddenVisibility);
+}
+
void CodeGenFunction::GenerateThunk(llvm::Function *Fn, GlobalDecl GD,
const ThunkInfo &Thunk) {
const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
@@ -2582,7 +2632,7 @@
CGM.setFunctionLinkage(MD, Fn);
// Set the right visibility.
- CGM.setGlobalVisibility(Fn, MD);
+ setThunkVisibility(CGM, MD, Thunk, Fn);
}
void CodeGenVTables::EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk)