Factor vtable related GlobalVariable creation out into a separate function. Add vtable linkage test.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@90667 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGenCXX/vtable-linkage.cpp b/test/CodeGenCXX/vtable-linkage.cpp
new file mode 100644
index 0000000..3a1d8f3
--- /dev/null
+++ b/test/CodeGenCXX/vtable-linkage.cpp
@@ -0,0 +1,18 @@
+// RUN: clang-cc %s -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck %s
+
+namespace {
+  // The vtables should have internal linkage.
+  struct A {
+    virtual void f() { }
+  };
+  
+  struct B : virtual A {
+    virtual void f() { } 
+  };
+
+  // CHECK: @_ZTVN12_GLOBAL__N_11BE = internal constant
+  // CHECK: @_ZTTN12_GLOBAL__N_11BE = internal constant
+  // CHECK: @_ZTVN12_GLOBAL__N_11AE = internal constant
+}
+
+void f() { B b; }