Migrate thunk-linkonce-odr.cpp from llvm/test/FrontendC++.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@137761 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGenCXX/thunk-linkonce-odr.cpp

@@ -0,0 +1,33 @@
+// RUN: %clang_cc1 %s -emit-llvm -o - | FileCheck %s
+// <rdar://problem/7929157> & <rdar://problem/8104369>
+
+struct A {
+  virtual int f() { return 1; }
+};
+
+struct B {
+  virtual int f() { return 2; }
+};
+
+struct C : A, B {
+  virtual int f() { return 3; }
+};
+
+struct D : C {
+  virtual int f() { return 4; }
+};
+
+static int f(D* d) {
+  B* b = d;
+  return b->f();
+};
+
+int g() {
+  D d;
+  return f(&d);
+}
+
+// Thunks should be marked as "linkonce ODR" not "weak".
+//
+// CHECK: define linkonce_odr i32 @_ZThn{{[48]}}_N1D1fEv
+// CHECK: define linkonce_odr i32 @_ZThn{{[48]}}_N1C1fEv