It turns out that linkers (at least, the Darwin linker) don't necessarily
do the right thing with mixed-visibility symbols, so disable the visibility
optimization where that's possible, i.e. with template classes (since it's
possible that an arbitrary template might be subject to an explicit
instantiation elsewhere). 447.dealII actually does this.
I've put the code under an option that's currently not hooked up to anything.
llvm-svn: 110374
diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index cd34d03..494176a 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -15,6 +15,7 @@
#include "CodeGenFunction.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/RecordLayout.h"
+#include "clang/Frontend/CodeGenOptions.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Support/Compiler.h"
@@ -2469,34 +2470,29 @@
// emit its thunks with hidden visibility, since its thunks must be
// emitted when the function is.
- // This mostly follows CodeGenModule::setTypeVisibility.
+ // This follows CodeGenModule::setTypeVisibility; see the comments
+ // there for explanation.
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_ExplicitSpecialization:
case TSK_ImplicitInstantiation:
+ if (!CGM.getCodeGenOpts().EmitWeakTemplatesHidden)
+ return;
break;
}
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 6338402..297aa45 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -229,6 +229,9 @@
// This isn't possible if there might be unresolved references
// elsewhere that rely on this symbol being visible.
+ // This should be kept roughly in sync with setThunkVisibility
+ // in CGVTables.cpp.
+
// Preconditions.
if (GV->getLinkage() != llvm::GlobalVariable::WeakODRLinkage ||
GV->getVisibility() != llvm::GlobalVariable::DefaultVisibility)
@@ -245,16 +248,20 @@
case TSK_ExplicitInstantiationDeclaration:
return;
- // Every use of a non-template or explicitly-specialized class's
- // type information has to emit it.
- case TSK_ExplicitSpecialization:
+ // Every use of a non-template class's type information has to emit it.
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.
+ // In theory, implicit instantiations can ignore the possibility of
+ // an explicit instantiation declaration because there necessarily
+ // must be an EI definition somewhere with default visibility. In
+ // practice, it's possible to have an explicit instantiation for
+ // an arbitrary template class, and linkers aren't necessarily able
+ // to deal with mixed-visibility symbols.
+ case TSK_ExplicitSpecialization:
case TSK_ImplicitInstantiation:
+ if (!CodeGenOpts.EmitWeakTemplatesHidden)
+ return;
break;
}