Re: [PATCH] Exploiting dual mode operation, implementation.

[Richard Henderson <rth at redhat dot com>]

On Mon, Aug 01, 2005 at 09:37:15PM +0300, Leehod Baruch wrote:
> use*2 is combined use that is done on SI mode.
> This way we save the sign-extension on the def1-use2 pass.

Hum.  Well, I supposed I missed that part of your discussion.  But that
aside, I *still* do not believe that narrowing from hi->di to hi->si is
useful.  They cost the same.  You're merely complicating things to try
to take this into account.

And, frankly, you'll find that essentially all of the optimization
that can happen for free comes on the producer side, and not on
the consumer side.  Thus I would expect the benefit to be had from
catering to a "use2" that can automagically widen si->di to be minimal.



r~