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Re: [PATCH] Initialize the entire obstack struct [BZ #17919]
- From: "Carlos O'Donell" <carlos at redhat dot com>
- To: Siddhesh Poyarekar <siddhesh at redhat dot com>
- Cc: bug-gnulib at gnu dot org, libc-alpha at sourceware dot org
- Date: Tue, 03 Feb 2015 13:14:06 -0500
- Subject: Re: [PATCH] Initialize the entire obstack struct [BZ #17919]
- Authentication-results: sourceware.org; auth=none
- References: <20150203145649 dot GG1528 at spoyarek dot pnq dot redhat dot com> <54D0F799 dot 2030204 at redhat dot com> <20150203163831 dot GL1528 at spoyarek dot pnq dot redhat dot com> <54D0FC16 dot 7090009 at redhat dot com> <20150203170511 dot GM1528 at spoyarek dot pnq dot redhat dot com>
On 02/03/2015 12:05 PM, Siddhesh Poyarekar wrote:
> On Tue, Feb 03, 2015 at 11:49:26AM -0500, Carlos O'Donell wrote:
>> IMO zero-initialized padding, for this case, isn't something you can
>> expect. Therefore I think it's a compiler bug.
>
> Thanks, I've filed a bug now:
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64923
>
>> I think it's OK to work around this in glibc, but it needs a comment
>> with a reference to the filed gcc bug. I do not think it is valid
>> for gcc on s390x to use the entire bit field along with padding and
>> I believe it could result in incorrect operation.
>
> Nothing is breaking due to this right now, so we could probably wait
> and see what the gcc folks think of this.
I would check it into 2.22 and reference the GCC PR.
However, I see that GCC thinks this is a valgrind bug.
If valgrind is simply looking at the comparison to make
the warning then it falls into the 'false positive' category.
In which case I think Valgrind should set up an exception for
this warning on s390.
Cheers,
Carlos.