[1/6 CRIS cc0-preparations] try to generate zero-based comparisons

[Jeff Law]

On Mon, 2020-02-10 at 17:55 +0100, Hans-Peter Nilsson wrote:
> * config/cris/cris.c (cris_reduce_compare): New function.
> * config/cris/cris-protos.h  (cris_reduce_compare): Add prototype.
> * config/cris/cris.md ("cbranch<mode>4", "cbranchdi4", "cstoredi4")
> (cstore<mode>4"): Apply cris_reduce_compare in expanders.
So just an FYI.  We've branched for gcc-10 and since this work primarily affects
the cris port, I think it can go in at your convenience.

THanks,
Jeff
>