Adjust the changes from r230255 to bail out if the backend can't lower
__builtin_setjmp/__builtin_longjmp and don't fall back to the libc
functions.

llvm-svn: 231245
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index d3d1e22..014ea9d 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -859,8 +859,11 @@
       return RValue::get(Builder.CreateZExt(Result, Int64Ty, "extend.zext"));
   }
   case Builtin::BI__builtin_setjmp: {
-    if (!getTargetHooks().hasSjLjLowering(*this))
-      break;
+    if (!getTargetHooks().hasSjLjLowering(*this)) {
+      CGM.ErrorUnsupported(E, "__builtin_setjmp");
+      return RValue::get(nullptr);
+    }
+
     // Buffer is a void**.
     Value *Buf = EmitScalarExpr(E->getArg(0));
 
@@ -883,8 +886,10 @@
     return RValue::get(Builder.CreateCall(F, Buf));
   }
   case Builtin::BI__builtin_longjmp: {
-    if (!getTargetHooks().hasSjLjLowering(*this))
-      break;
+    if (!getTargetHooks().hasSjLjLowering(*this)) {
+      CGM.ErrorUnsupported(E, "__builtin_longjmp");
+      return RValue::get(nullptr);
+    }
     Value *Buf = EmitScalarExpr(E->getArg(0));
     Buf = Builder.CreateBitCast(Buf, Int8PtrTy);