Re: [PATCH] Add testcase for PR83252 (was Re: patch to fix PR80818)

[Vladimir Makarov <vmakarov at redhat dot com>]

On 12/05/2017 07:49 AM, Jakub Jelinek wrote:
> On Mon, Dec 04, 2017 at 11:52:01AM +0100, Jakub Jelinek wrote:
> > On Wed, Nov 29, 2017 at 05:21:22PM -0500, Vladimir Makarov wrote:
> > >    The following patch fixes
> > >
> > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80818
> > >
> > >    The patch was successfully tested and bootstrapped on x86_64. The patch
> > > has no test because it is hard to check the problem.  I checked manually
> > This changed fixed PR83252 which has a reasonably small testcase.
> > I've further reduced it using creduce (with -O0 -W{,maybe-}uninitialized
> > and/or -fsanitize=undefined checking, plus test that it succeeds with
> > r255258 and fails with r255257).  Can you please double check if the
> > testcase represents the same issue you were working on or if your change
> > merely made the bug latent again?
> Unfortunately, it broke again with r255377.  Vladimir, could you please have
> a look at this PR?
Yes, I'll work on it.

The more I look at the problem discussed in PR80818, PR83252, and 
PR83245, the more I think it is actually a LRA rematerialziation problem.