[PowerPC] add a testcase for reverse memory op; nfc

Author: Chen Zheng

llvm/test/CodeGen/PowerPC/vsx-shuffle-le-load.ll

@@ -0,0 +1,16 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -verify-machineinstrs -mcpu=pwr9 -mattr=+vsx \
+; RUN:   -mtriple=powerpc64le-unknown-linux-gnu < %s | FileCheck %s
+
+define <2 x double> @loadChainHasUser(<2 x double>* %p1, <2 x double> %v2) {
+; CHECK-LABEL: loadChainHasUser:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    lxv 0, 0(3)
+; CHECK-NEXT:    stxv 34, 0(3)
+; CHECK-NEXT:    xxswapd 34, 0
+; CHECK-NEXT:    blr
+  %v1 = load <2 x double>, <2 x double>* %p1
+  store <2 x double> %v2, <2 x double>* %p1, align 16
+  %v3 = shufflevector <2 x double> %v1, <2 x double> %v1, <2 x i32> < i32 1, i32 0>
+  ret <2 x double> %v3
+}