Rerunning CSE after GCSE

[Richard Kenner]

    However, consider that cse.c has more code to handle costing, more
    simplifications, etc than gcse.c  Also consider that gcse.c doesn't work
    at all on hard regs -- it seems them and gives up.

That may not matter.  If gcse moves one expression into a basic block and
CSE does the rest, it may be enough.  It would be good if somebody could
measure if -fcse-skip-blocks and -fcse-follow-jumps really do anything.