filler such as if delay slot filler have to put NOP instruction into the
delay slot of microMIPS BEQ or BNE instruction which uses the register $0,
then instead of emitting NOP this instruction is replaced by the corresponding
microMIPS compact branch instruction, i.e. BEQZC or BNEZC.
Differential Revision: http://reviews.llvm.org/D3566
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222580 91177308-0d34-0410-b5e6-96231b3b80d8
