F21 system GCC changed to 4.9.0 prerelease

Jakub Jelinek jakub at redhat.com
Fri Apr 11 09:10:55 UTC 2014

On Fri, Apr 11, 2014 at 11:32:53AM +0300, Panu Matilainen wrote:
> On 04/10/2014 05:38 PM, Richard W.M. Jones wrote:
> >On Thu, Apr 10, 2014 at 12:23:07PM +0200, Jakub Jelinek wrote:
> >>To investigate runtime rather than compile time
> >>issues, please consider using temporarily -fsanitize=undefined and/or
> >>-fsanitize=address to look for undefined behavior in the packages
> >>you own.
> >
> >Which is this in case anyone else was wondering:
> >
> >   '-fsanitize=address'
> >      Enable AddressSanitizer, a fast memory error detector.  Memory
> >      access instructions will be instrumented to detect out-of-bounds
> >      and use-after-free bugs.  See
> >      <http://code.google.com/p/address-sanitizer/> for more details.
> >      The run-time behavior can be influenced using the 'ASAN_OPTIONS'
> >      environment variable; see
> >      <https://code.google.com/p/address-sanitizer/wiki/Flags#Run-time_flags>
> >      for a list of supported options.
> Also in case anybody else wonders about gcc failing to recognize
> these options, you'll need to add BuildRequires for these: libasan
> for -fsanitize=address and libubsan for -fsanitize=undefined (and
> similarly for leak and thread sanitizers )

Yeah.  But, note that the sanitizers are meant primarily for development,
not for production, and especially -fsanitize=thread and to some extent
-fsanitize=address aren't completely cheap, so if you do that, please do
so temporarily and don't forget to disable it again for production.


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