Update amdgpu-lower-exec-sync.ll test with llc RUN line

Author: skc7

llvm/test/CodeGen/AMDGPU/amdgpu-lower-exec-sync.ll

@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals all --version 6
 ; RUN: opt -S -mtriple=amdgcn-- -amdgpu-lower-exec-sync < %s 2>&1 | FileCheck %s
+; RUN: llc < %s -enable-new-pm -stop-after=amdgpu-lower-exec-sync -mtriple=amdgcn-amd-amdhsa | FileCheck %s
 
 %class.ExpAmdWorkgroupWaveBarrier = type { target("amdgcn.named.barrier", 0) }