[Clang][CodeGen][NFC] Add (broken) test case for GH67937

This adds a test case for yet unfixed #67937

Author: mizvekov

clang/test/CodeGenCXX/strict-vtable-pointers-GH67937.cpp

@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 %s -I%S -triple=x86_64-pc-windows-msvc -fstrict-vtable-pointers -disable-llvm-passes -disable-llvm-verifier -O1 -emit-llvm -o %t.ll
+// RUN: FileCheck %s < %t.ll
+// RUN: not llvm-as < %t.ll -o /dev/null 2>&1 | FileCheck %s --check-prefix=CHECK-VERIFIER
+
+struct A {
+  virtual ~A();
+};
+struct B : virtual A {};
+class C : B {};
+C foo;
+
+// FIXME: This is not supposed to generate invalid IR!
+// CHECK-VERIFIER: Instruction does not dominate all uses!
+// CHECK-VERIFIER-NEXT: %1 = call ptr @llvm.launder.invariant.group.p0(ptr %this1)
+// CHECK-VERIFIER-NEXT: %3 = call ptr @llvm.launder.invariant.group.p0(ptr %1)
+
+// CHECK-LABEL: define {{.*}} @"??0C@@QEAA@XZ"(ptr {{.*}} %this, i32 {{.*}} %is_most_derived)
+// CHECK: ctor.init_vbases:
+// CHECK-NEXT: %0 = getelementptr inbounds i8, ptr %this1, i64 0
+// CHECK-NEXT: store ptr @"??_8C@@7B@", ptr %0
+// CHECK-NEXT: %1 = call ptr @llvm.launder.invariant.group.p0(ptr %this1)
+// CHECK-NEXT: %2 = getelementptr inbounds i8, ptr %1, i64 8
+// CHECK-NEXT: %call = call noundef ptr @"??0A@@QEAA@XZ"(ptr {{.*}} %2) #2
+// CHECK-NEXT: br label %ctor.skip_vbases
+// CHECK-EMPTY:
+// CHECK-NEXT: ctor.skip_vbases:
+// FIXME: Should be using '%this1' instead of %1 below.
+// CHECK-NEXT: %3 = call ptr @llvm.launder.invariant.group.p0(ptr %1)
+// CHECK-NEXT: %call3 = call noundef ptr @"??0B@@QEAA@XZ"(ptr {{.*}} %3, i32 noundef 0) #2