[patch] tree-ssa-forwprop.c: Rewrite.

[Jeffrey A Law]

On Tue, 2005-04-12 at 14:59 -0400, Kazu Hirata wrote:

> Sure.  I was actually thinking about extending this rewritten forwprop
> pass.  Unlike the RTL combiner, GIMPLE doesn't have a lot of
> combinable cases if we want to fold multiple statements into a single
> GIMPLE statement, so for a start, I am thinking about detecting common
> combinable cases like two successive casts and whatnot and let fold do
> its job.
Rather than just extending the existing code, please try to start
factoring it into a more generic tree combiner.

While I agree completely that we're not going to see as many combining
opportunities as we see at the RTL level, the opportunities do exist --
we've had several discussions about them throughout the last two years.

Jeff