[Bug tree-optimization/22630] [4.1 Regression] vrp produces wrong code

["law at redhat dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From law at redhat dot com  2005-07-27 16:55 -------
Subject: Re:  [4.1 Regression] vrp produces
	wrong code

On Wed, 2005-07-27 at 16:34 +0000, ja2morri at csclub dot uwaterloo dot
ca wrote:
> ------- Additional Comments From ja2morri at csclub dot uwaterloo dot ca  2005-07-27 16:34 -------
> Subject: Re:  [4.1 Regression] vrp produces
>  wrong code
> 
> 
> Jeffrey A Law <law@redhat.com> writes:
> 
> > The underlying problem here is the code to meet a VR_ANTI_RANGE and
> > a VR_RANGE does not intersect the equivalence sets.  This in turn
> > causes the VRP code to incorrectly evaluate a conditional.  It's
> > all downhill after that.
> >
> > While investigating this problem I also noticed that the vrp_meet
> > code does not properly handle intersecting the equivalence sets
> > when vr0 has a set, but vr1 does not (their intersection is the
> > null set of course).  This patch fixes that oversight as well.
> >
> > Bootstrapped and regression tested on i686-pc-linux-gnu.
> >
> > jeff
> 
>  You added 3 bitmap_clear calls here, do you have any testcases that
> exercise this code?
No, but the code is clearly wrong by inspection.  

jeff




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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22630