Why can't CSE recognize const_int's in HIGH LO_SUM pair?

[John David Anglin]

> Better would be to emit the actual constants that the insns
> in question will load into the hardware registers.

Jeff probably could give the best answer but I think it has to do with
the way move insns are done in general.  I think the philosophy was to
make the rtl match as closely as possible the machine code.  However, I recall
a few months ago there were issues with high/lo_sum in pic code generation 
and one of the solutions discussed was delaying the generation of high/lo_sum
pairs until after reload.  Clearly, it is easier for the compiler to
deal with a simple constant or address.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)