implement support for __builtin_eh_return_data_regno on x86-32 and x86-64.
This implements PR5034 and rdar://6836445.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@82614 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Sema/builtins.c b/test/Sema/builtins.c
index c3daa66..04a56bd 100644
--- a/test/Sema/builtins.c
+++ b/test/Sema/builtins.c
@@ -52,3 +52,13 @@
  
   // No warning about falling off the end of a noreturn function.
 }
+
+void test11(int X) {
+  switch (X) {  
+  case __builtin_eh_return_data_regno(0):  // constant foldable.
+    break;
+  }
+
+  __builtin_eh_return_data_regno(X);  // expected-error {{not an integer constant expression}}
+}
+