From: Eric Botcazou <ebotcazou@libertysurf.fr>
Date: Fri, 23 Jun 2017 17:50:17 +0000
Subject: Re: sparc gcc 7.1 compile issue
Message-Id: <1611462.j5lKuWamyW@polaris>
List-Id: <sparclinux.vger.kernel.org>
References: <20170531193431.GA26922@waldemar-brodkorb.de>
In-Reply-To: <20170531193431.GA26922@waldemar-brodkorb.de>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: sparclinux@vger.kernel.org

> Thanks for the explanation. We're now just disabling cilk on Debian
> for gcc-7 and gcc-snapshot for the time being.

I just fixed the problem on the mainline and 7 branch:
  https://gcc.gnu.org/ml/gcc-patches/2017-06/msg01818.html

The testsuite now flawlessly passes at -j32 for me.

> Ok, I hope that will help the kernel guys to figure out what the
> problem is.

libcilkrts does low-level fiddling with the stack pointer and threads, and 
overlooked the stack bias in 64-bit mode.  This resulted in reproducible hangs 
for some tests of the testsuite and I guess that a high level of parallelism 
led to a form of congestion somewhere; I'm afraid I can't say more.

-- 
Eric Botcazou