Re: [PATCH GCC][1/2]Feed bound computation to folder in loop split

[Marc Glisse <marc dot glisse at inria dot fr>]

On Tue, 25 Jul 2017, Richard Biener wrote:

> > I think we need Richard to say what the intent is for the valueization
> > function. It is used both to stop looking at defining stmt if the return is
> > NULL, and to replace/optimize one SSA_NAME with another, but currently it
> > seems hard to prevent looking at the defining statement without preventing
> > from looking at the SSA_NAME at all.
>
> Yeah, this semantic overloading is an issue.  For gimple_build we have nothing
> to "valueize" but we only use it to tell genmatch that it may not look at the
> SSA_NAME_DEF_STMT.
>
> > I guess we'll need a fix in genmatch...
>
> I'll have a look tomorrow.

My impression yesterday was that we could replace the current do_valueize 
wrapper by 2 wrappers (without touching the valueize callbacks):
- may_check_def_stmt, which returns a bool corresponding to the current 
do_valueize != NULL_TREE
- maybe_valueize, which tries to valueize, but if it gets a NULL_TREE, 
it returns its argument unchanged.

Not very confident about it though.

--
Marc Glisse