[Bug rtl-optimization/37516] ~(-2 - a) is not being optimized into a + 1

["rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516

--- Comment #5 from rguenther at suse dot de <rguenther at suse dot de> 2012-02-24 08:38:19 UTC ---
On Thu, 23 Feb 2012, pinskia at gcc dot gnu.org wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37516
> 
> --- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-02-23 22:15:05 UTC ---
> 
> > Maybe get away with these old-stylish names ('tree' and 'fold') and
> > make it match reality, gimple-ssa-combine.c ;)
> 
> That sounds like a good idea.  I have done that.
> 
> > 
> > Still have to have a look at your branch - do you have a brief
> > overview documentation, for example on the wiki?  What I'd like
> > to do is have an interface that I can re-use for VN combining,
> > basically replace its simplify_*_expression functions.
> 
> I don't have one yet.  But I hope to create one this weekend.
> 
> Right now replacing the VN combining with this new functionality will not work
> as it scans the defs itself.  Though I am moving all the def scanning to its
> own function which should allow for the code to be more modular and allow for
> the VN combining to work with it.

I think def scanning is ok, but all SSA names should be "valueized" via
a hook first.

Richard.