Re: Enabling compiler warning flags

[Jeffrey Walton]

On Tue, Feb 26, 2013 at 8:01 AM, Eric Blake <address@hidden> wrote:
> On 02/25/2013 06:09 PM, Jeffrey Walton wrote:
>
>> GCC 4.8 added a couple of interesting flags
>> (http://gcc.gnu.org/gcc-4.8/changes.html): -fsanitize=address and
>> -fsanitize=thread. Some reading about them is available at
>> http://llvm.org/devmtg/2012-11/Serebryany_TSan-MSan.pdf.
>>
>> It might be helpful to projects if the auto tools enabled one or both
>> by default. The overhead on Address Sanitizer looks small compared to
>> the payoff.
>
> That paper said address sanitizer added 2x slowdown (20x under
> valgrind), and would need hardware support to cut the slowdown to only
> 20%.  It also said thread sanitizer added 20x to 300x slowdown.  That
> sounds like neither one should be enabled by default, but are best used
> during development.  But thanks for pointing them out - they sound
> interesting.
Yes, my bad. Address Sanitizer should be enabled for debug
configurations by default (along with other "program diagnostics" to
borrow from Posix).

Release configurations should leave the choice to the user.

Jeff