[MS] Pass CalleeDecl to adjustThisArgumentForVirtualFunctionCall

If we are devirtualizing, then we want to compute the 'this' adjustment
of the devirtualized target, not the adjustment of the base's method
definition, which is usually zero.

Fixes PR27621

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@268418 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 0 deletions

diff --git a/test/CodeGenCXX/microsoft-abi-virtual-inheritance.cpp b/test/CodeGenCXX/microsoft-abi-virtual-inheritance.cpp
index 8897a38443..f4a6e30119 100644
--- a/test/CodeGenCXX/microsoft-abi-virtual-inheritance.cpp
+++ b/test/CodeGenCXX/microsoft-abi-virtual-inheritance.cpp
@@ -481,3 +481,21 @@ C::C() : B() {}
 // CHECK:   %[[FIELD:.*]] = getelementptr inbounds i8, i8* %[[B_i8]], i32 4
 // CHECK:   call void @llvm.memset.p0i8.i32(i8* %[[FIELD]], i8 0, i32 4, i32 4, i1 false)
 }
+
+namespace pr27621 {
+// Devirtualization through a static_cast used to make us compute the 'this'
+// adjustment for B::g instead of C::g. When we directly call C::g, 'this' is a
+// B*, and the prologue of C::g will adjust it to a C*.
+struct A { virtual void f(); };
+struct B { virtual void g(); };
+struct C final : A, B {
+  virtual void h();
+  void g() override;
+};
+void callit(C *p) {
+  static_cast<B*>(p)->g();
+}
+// CHECK-LABEL: define void @"\01?callit@pr27621@@YAXPAUC@1@@Z"(%"struct.pr27621::C"* %{{.*}})
+// CHECK: %[[B_i8:.*]] = getelementptr i8, i8* %1, i32 4
+// CHECK: call x86_thiscallcc void @"\01?g@C@pr27621@@UAEXXZ"(i8* %[[B_i8]])
+}