Give explicit template instantiations weak linkage (but don't defer

them). Fixes PR6578.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@98328 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 12 insertions, 9 deletions

diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index c67948d27f..7314dae813 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -285,8 +285,7 @@ GetLinkageForFunction(ASTContext &Context, const FunctionDecl *FD,
       break;
 
     case TSK_ExplicitInstantiationDefinition:
-      // FIXME: explicit instantiation definitions should use weak linkage
-      return CodeGenModule::GVA_StrongExternal;
+      return CodeGenModule::GVA_ExplicitTemplateInstantiation;
 
     case TSK_ExplicitInstantiationDeclaration:
     case TSK_ImplicitInstantiation:
@@ -335,7 +334,8 @@ CodeGenModule::getFunctionLinkage(const FunctionDecl *D) {
     // In C99 mode, 'inline' functions are guaranteed to have a strong
     // definition somewhere else, so we can use available_externally linkage.
     return llvm::Function::AvailableExternallyLinkage;
-  } else if (Linkage == GVA_CXXInline || Linkage == GVA_TemplateInstantiation) {
+  } else if (Linkage == GVA_CXXInline || Linkage == GVA_TemplateInstantiation ||
+             Linkage == GVA_ExplicitTemplateInstantiation) {
     // In C++, the compiler has to emit a definition in every translation unit
     // that references the function.  We should use linkonce_odr because
     // a) if all references in this translation unit are optimized away, we
@@ -589,6 +589,7 @@ bool CodeGenModule::MayDeferGeneration(const ValueDecl *Global) {
 
     // static, static inline, always_inline, and extern inline functions can
     // always be deferred.  Normal inline functions can be deferred in C99/C++.
+    // Implicit template instantiations can also be deferred in C++.
     if (Linkage == GVA_Internal || Linkage == GVA_C99Inline ||
         Linkage == GVA_CXXInline || Linkage == GVA_TemplateInstantiation)
       return true;
@@ -1043,15 +1044,15 @@ GetLinkageForVariable(ASTContext &Context, const VarDecl *VD) {
     switch (TSK) {
     case TSK_Undeclared:
     case TSK_ExplicitSpecialization:
-
-      // FIXME: ExplicitInstantiationDefinition should be weak!
-    case TSK_ExplicitInstantiationDefinition:
       return CodeGenModule::GVA_StrongExternal;
-      
+
     case TSK_ExplicitInstantiationDeclaration:
       llvm_unreachable("Variable should not be instantiated");
       // Fall through to treat this like any other instantiation.
         
+    case TSK_ExplicitInstantiationDefinition:
+      return CodeGenModule::GVA_ExplicitTemplateInstantiation;
+
     case TSK_ImplicitInstantiation:
       return CodeGenModule::GVA_TemplateInstantiation;      
     }
@@ -1171,7 +1172,8 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
       GV->setLinkage(llvm::GlobalVariable::WeakODRLinkage);
     else
       GV->setLinkage(llvm::GlobalVariable::WeakAnyLinkage);
-  } else if (Linkage == GVA_TemplateInstantiation)
+  } else if (Linkage == GVA_TemplateInstantiation || 
+             Linkage == GVA_ExplicitTemplateInstantiation)
     GV->setLinkage(llvm::GlobalVariable::WeakAnyLinkage);   
   else if (!getLangOptions().CPlusPlus && !CodeGenOpts.NoCommon &&
            !D->hasExternalStorage() && !D->getInit() &&
diff --git a/lib/CodeGen/CodeGenModule.h b/lib/CodeGen/CodeGenModule.h
index 40dc563889..9077adedd0 100644
--- a/lib/CodeGen/CodeGenModule.h
+++ b/lib/CodeGen/CodeGenModule.h
@@ -437,7 +437,8 @@ public:
     GVA_C99Inline,
     GVA_CXXInline,
     GVA_StrongExternal,
-    GVA_TemplateInstantiation
+    GVA_TemplateInstantiation,
+    GVA_ExplicitTemplateInstantiation
   };
 
   llvm::GlobalVariable::LinkageTypes