[X86] Add test showing failure to combine shuffle to bit rotation

Author: RKSimon

llvm/test/CodeGen/X86/vector-shuffle-combining-xop.ll

@@ -252,6 +252,15 @@ define <4 x i32> @combine_vpperm_10zz32BA(<4 x i32> %a0, <4 x i32> %a1) {
   ret <4 x i32> %res3
 }
 
+define <16 x i8> @combine_vpperm_as_proti_v8i16(<16 x i8> %a0, <16 x i8> %a1) {
+; CHECK-LABEL: combine_vpperm_as_proti_v8i16:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vpperm {{.*#+}} xmm0 = xmm0[1,0,3,2,5,4,7,6,9,8,11,10,13,12,15,14]
+; CHECK-NEXT:    ret{{[l|q]}}
+  %res0 = call <16 x i8> @llvm.x86.xop.vpperm(<16 x i8> %a0, <16 x i8> %a1, <16 x i8> <i8 1, i8 0, i8 3, i8 2, i8 5, i8 4, i8 7, i8 6, i8 9, i8 8, i8 11, i8 10, i8 13, i8 12, i8 15, i8 14>)
+  ret <16 x i8> %res0
+}
+
 define <16 x i8> @combine_shuffle_proti_v2i64(<2 x i64> %a0) {
 ; CHECK-LABEL: combine_shuffle_proti_v2i64:
 ; CHECK:       # %bb.0: