When we know that a dynamic_cast always returns null, we can make

CodeGenFunction::EmitDynamicCast always return null or throw a bad_cast 
exception.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@129264 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 19 insertions, 0 deletions

diff --git a/test/CodeGenCXX/dynamic-cast-always-null.cpp b/test/CodeGenCXX/dynamic-cast-always-null.cpp
new file mode 100644
index 0000000000..48ec69226c
--- /dev/null
+++ b/test/CodeGenCXX/dynamic-cast-always-null.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -I%S %s -triple x86_64-apple-darwin10 -emit-llvm -fcxx-exceptions -fexceptions -std=c++0x -o - | FileCheck %s
+struct A { virtual ~A(); };
+struct B final : A { };
+struct C { virtual ~C(); };
+
+// CHECK: @_Z1fP1B
+C *f(B* b) {
+  // CHECK-NOT: call i8* @__dynamic_cast
+  // CHECK: ret %struct.C* null
+  return dynamic_cast<C*>(b);
+}
+
+// CHECK: @_Z1fR1B
+C &f(B& b) {
+  // CHECK-NOT: call i8* @__dynamic_cast
+  // CHECK: call void @__cxa_bad_cast() noreturn
+  // CHECK: ret %struct.C* undef
+  return dynamic_cast<C&>(b);
+}