Itanium ABI: Update getAddrOfVTable to set the DLL storage class for vtables

[hans]

Summary

This corresponds to the same change for the MS ABI in r209908 and makes us pass more of Nico's tests.

[rnk]

lgtm

test/CodeGenCXX/dllimport.cpp

530

Can you test the case where the vtable is external? A class with a key function at -O0 should do.

In related news, we don't appear to emit available_externally vtables for classes with key functions at -O1. That seems like a bad missed optimization.

[hans]

Closed by commit rL210054 (authored by @hans).

lib/CodeGen/ItaniumCXXABI.cpp

llvm::GlobalVariable *ItaniumCXXABI::getAddrOfVTable(const CXXRecordDecl *RD,
 
   ItaniumVTableContext &VTContext = CGM.getItaniumVTableContext();
   llvm::ArrayType *ArrayType = llvm::ArrayType::get(
       CGM.Int8PtrTy, VTContext.getVTableLayout(RD).getNumVTableComponents());
 
   VTable = CGM.CreateOrReplaceCXXRuntimeVariable(
       Name, ArrayType, llvm::GlobalValue::ExternalLinkage);
   VTable->setUnnamedAddr(true);
+
+  if (RD->hasAttr<DLLImportAttr>())
+    VTable->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
+  else if (RD->hasAttr<DLLExportAttr>())
+    VTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
+
   return VTable;
 }
 
 llvm::Value *ItaniumCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF,
                                                       GlobalDecl GD,
                                                       llvm::Value *This,
                                                       llvm::Type *Ty) {
   GD = GD.getCanonicalDecl();

test/CodeGenCXX/dllexport.cpp

 
 struct __declspec(dllexport) W { virtual void foo() {} };
 // Default ctor:
 // M32-DAG: define weak_odr dllexport x86_thiscallcc %struct.W* @"\01??0W@@QAE@XZ"
 // Copy ctor:
 // M32-DAG: define weak_odr dllexport x86_thiscallcc %struct.W* @"\01??0W@@QAE@ABU0@@Z"
 // vftable:
 // M32-DAG: @"\01??_7W@@6B@" = weak_odr dllexport unnamed_addr constant [1 x i8*] [i8* bitcast (void (%struct.W*)* @"\01?foo@W@@UAEXXZ" to i8*)]
+// G32-DAG: @_ZTV1W = weak_odr dllexport unnamed_addr constant [3 x i8*] [i8* null, i8* bitcast ({ i8*, i8* }* @_ZTI1W to i8*), i8* bitcast (void (%struct.W*)* @_ZN1W3fooEv to i8*)]
 
 struct __declspec(dllexport) X : public virtual W {};
 // vbtable:
 // M32-DAG: @"\01??_8X@@7B@" = weak_odr dllexport unnamed_addr constant [2 x i32] [i32 0, i32 4]
 
 struct __declspec(dllexport) Y {
   // Move assignment operator:
   // M32-DAG: define weak_odr dllexport x86_thiscallcc nonnull %struct.Y* @"\01??4Y@@QAEAAU0@$$QAU0@@Z"

test/CodeGenCXX/dllimport.cpp

 // MO1-DAG: define available_externally dllimport x86_thiscallcc void @"\01?foo@?$U@H@@QAEXXZ"
 struct __declspec(dllimport) V : public U<int> { };
 USEMEMFUNC(V, foo)
 
 struct __declspec(dllimport) W { virtual void foo() {} };
 USECLASS(W)
 // vftable:
 // MO1-DAG: @"\01??_7W@@6B@" = available_externally dllimport unnamed_addr constant [1 x i8*] [i8* bitcast (void (%struct.W*)* @"\01?foo@W@@UAEXXZ" to i8*)]
+// GO1-DAG: @_ZTV1W = available_externally dllimport unnamed_addr constant [3 x i8*] [i8* null, i8* null, i8* bitcast (void (%struct.W*)* @_ZN1W3fooEv to i8*)]
 
 struct __declspec(dllimport) X : public virtual W {};
 USECLASS(X)
 // vbtable:
 // MO1-DAG: @"\01??_8X@@7B@" = available_externally dllimport unnamed_addr constant [2 x i32] [i32 0, i32 4]
 
 struct __declspec(dllimport) Y {
   int x;