This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: A bug in vrp_meet?
On Wed, Mar 6, 2019 at 11:05 AM Richard Biener
<richard.guenther@gmail.com> wrote:
>
> On Tue, Mar 5, 2019 at 10:36 PM Jeff Law <law@redhat.com> wrote:
> >
> > On 3/5/19 7:44 AM, Richard Biener wrote:
> >
> > > So fixing it properly with also re-optimize_stmt those stmts so we'd CSE
> > > the MAX_EXPR introduced by folding makes it somewhat ugly.
> > >
> > > Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
> > >
> > > Any ideas how to make it less so? I can split out making optimize_stmt
> > > take a gsi * btw, in case that's a more obvious change and it makes the
> > > patch a little smaller.
> > >
> > > Richard.
> > >
> > > 2019-03-05 Richard Biener <rguenther@suse.de>
> > >
> > > PR tree-optimization/89595
> > > * tree-ssa-dom.c (dom_opt_dom_walker::optimize_stmt): Take
> > > stmt iterator as reference, take boolean output parameter to
> > > indicate whether the stmt was removed and thus the iterator
> > > already advanced.
> > > (dom_opt_dom_walker::before_dom_children): Re-iterate over
> > > stmts created by folding.
> > >
> > > * gcc.dg/torture/pr89595.c: New testcase.
> > >
> >
> > Well, all the real logic changs are in the before_dom_children method.
> > The bits in optimize_stmt are trivial enough to effectively ignore.
> >
> > I don't see a better way to discover and process statements that are
> > created in the bowels of fold_stmt.
>
> I'm not entirely happy so I created the following alternative which
> is a bit larger and slower due to the pre-pass clearing the visited flag
> but is IMHO easier to follow. I guess there's plenty of TLC opportunity
> here but then I also hope to retire the VN parts of DOM in favor
> of the non-iterating RPO-VN code...
>
> So - I'd lean to this variant even though it has the extra loop over stmts,
> would you agree?
I have now applied this variant.
Richard.
> Bootstrap / regtest running on x86_64-unknown-linux-gnu.
>
> Richard.
>
> 2019-03-06 Richard Biener <rguenther@suse.de>
>
> PR tree-optimization/89595
> * tree-ssa-dom.c (dom_opt_dom_walker::optimize_stmt): Take
> stmt iterator as reference, take boolean output parameter to
> indicate whether the stmt was removed and thus the iterator
> already advanced.
> (dom_opt_dom_walker::before_dom_children): Re-iterate over
> stmts created by folding.
>
> * gcc.dg/torture/pr89595.c: New testcase.