[tree-ssa] Re: PATCH: [gcc3.5 improvement branch] Very Simple constant propagation

[Jan Hubicka]

> In message <20040116001814.GA13682@kam.mff.cuni.cz>, Jan Hubicka writes:
>  >Yes, I invented that code some time ago.  I really think that in
>  >post-SSA world we should not do the trick on RTL.
> Agreed.
> 
>  >  Perhaps the patch
>  >would need to wait for SSA equivalent of this transform that I can do
>  >soon if this is considered important feature.
> Precisely.
> 
>  >Dom doesn't have def-use chains readilly available, right?
> Nope, but it wouldn't be that hard to make then available (keeping them
> up-to-date might be more difficult).

Afaik Zdenek has proposed patch for this.
> 
> My question is does this belong in dom at all.  While we might want to
> do it as part of a dominator walk or other transforming pass, I don't
> see that it needs to live in the current dominator optimizer.  Unless
> it's like to expose lots of additional optimization opportunities.

I wonder where to place it right now.  Do we have some other pass that
walks the whole chain where this can be placed?
Or shall I invent new one.  I think this can be run just after profile
is constructed and it can be place where our current profile value
transformation pass should be placed, so perhaps I can simply start
this.  If this sounds sane, I can implement the new pass this week.

Honza
> 
> 
> jeff