Before this was just writing 0s, which ends up looking like a v_cndmask_b32 v0, s0, v0, vcc. Write out an encoded s_nop instead. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299816 91177308-0d34-0410-b5e6-96231b3b80d8