How to represent conditional compare in RTL?

Hi Richard,

After adding some new ops, I can keep the conditional compare to the end of tree-level optimization. As tests, I expand conditional compare to BIT_AND_EXPR/BIT_IOR_EXPR, which still depend on later "combine" pass to combine them.

Is it possible to expand it to *cmp_and/*cmp_ior like patterns? What's the expected RTL representation for conditional compare after expand and before combine?

Thanks! -Zhenqiang