[X86] Add the test case for r315613 that I forgot to 'git add'.

llvm-svn: 315649
diff --git a/llvm/test/CodeGen/X86/clwb.ll b/llvm/test/CodeGen/X86/clwb.ll
new file mode 100644
index 0000000..fe11383
--- /dev/null
+++ b/llvm/test/CodeGen/X86/clwb.ll
@@ -0,0 +1,13 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=i686-apple-darwin -mattr=clwb | FileCheck %s
+
+define void @clwb(i8* %p) nounwind {
+; CHECK-LABEL: clwb:
+; CHECK:       ## BB#0:
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT:    clwb (%eax)
+; CHECK-NEXT:    retl
+  tail call void @llvm.x86.clwb(i8* %p)
+  ret void
+}
+declare void @llvm.x86.clwb(i8*) nounwind