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Re: [PATCH] Initialize the entire obstack struct [BZ #17919]
- From: pinskia at gmail dot com
- To: Siddhesh Poyarekar <siddhesh at redhat dot com>
- Cc: Carlos O'Donell <carlos at redhat dot com>, "bug-gnulib at gnu dot org" <bug-gnulib at gnu dot org>, "libc-alpha at sourceware dot org" <libc-alpha at sourceware dot org>
- Date: Tue, 3 Feb 2015 09:10:50 -0800
- 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 Feb 3, 2015, at 9:05 AM, Siddhesh Poyarekar <email@example.com> 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:
It is not a glibc or a gcc bug but rather a valgrind one. We are comparing against zero since this is the sign bit. Valgrind does not realize that and gives a warning.
>> 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.