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Re: [PATCH] Fix GLIBC build error with recent GCC6

From: Jeff Law <law at redhat dot com>
To: Florian Weimer <fweimer at redhat dot com>, "Carlos O'Donell" <carlos at redhat dot com>, Wilco Dijkstra <wdijkstr at arm dot com>, "'GNU C Library'" <libc-alpha at sourceware dot org>
Date: Mon, 20 Jul 2015 11:53:07 -0600
Subject: Re: [PATCH] Fix GLIBC build error with recent GCC6
Authentication-results: sourceware.org; auth=none
References: <002b01d0c309$84ed71a0$8ec854e0$ at com> <55AD32AB dot 8020004 at redhat dot com> <55AD3401 dot 4020005 at redhat dot com> <55AD3511 dot 4040804 at redhat dot com>

On 07/20/2015 11:51 AM, Florian Weimer wrote:

On 07/20/2015 07:46 PM, Jeff Law wrote:

Extra credit if you can file a bug report upstream for GCC.


<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66946>

This kind of false positive often leads to discovery of cases that GCC
is not optimizing as well as it should.  Killing the false positive and
generating better code in the process is obviously a good thing.


What's particularly worrying is that the warning says “is”, not ”may
be”.  Doesn't this indicate the GCC miscompiles some paths?

Not really. I'd have to sit down with the minimized testcase & a CFG toknow for sure.


jeff

References:
- [PATCH] Fix GLIBC build error with recent GCC6
  - From: Wilco Dijkstra
- Re: [PATCH] Fix GLIBC build error with recent GCC6
  - From: Carlos O'Donell
- Re: [PATCH] Fix GLIBC build error with recent GCC6
  - From: Jeff Law
- Re: [PATCH] Fix GLIBC build error with recent GCC6
  - From: Florian Weimer

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