Re: Problems in IPA passes

[Jan Hubicka <jh at suse dot de>]

Dne 2017-10-28 09:28, Jeff Law napsal:
> Jan,
>
> What's the purpose behind calling vrp_meet and
> extract_range_from_unary_expr from within the IPA passes?
>
> AFAICT that is not safe to do.  Various paths through those routines
> will access static objects within tree-vrp.c which may not be
> initialized when IPA runs (vrp_equiv_obstack, vr_value).
>
> While this seems to be working today, it's a failure waiting to happen.
>
> Is there any way you can avoid using those routines?  I can't believe
> you really need all the complexity of those routines, particularly
> extract_range_from_unary_expr.  Plus it's just downright fugly from a
> modularity standpoint.

We now have three value range propagation passes.  The original vrp, 
early vrp
which is fater and ipa-cp which does IPA propagation. It seems sane to 
me for those
three to share some infrastructure but I did not look in enough of 
detail into
these to know if what we have right now is sane thing to do :)

The VRP passes were introduced by Kugan and this part was mostly 
reviewed by
Richi, so I am adding them to CC.
The refactoring happened in 
https://gcc.gnu.org/ml/gcc-patches/2016-07/msg00891.html

Honza
> ?
>
> Jeff