Fwd: [PATCH] Turn off -Wmaybe-uninitialized when building with -Os
Russell King - ARM Linux
linux at arm.linux.org.uk
Fri Mar 15 14:12:46 EDT 2013
On Fri, Mar 15, 2013 at 02:55:38PM +0000, Arnd Bergmann wrote:
> I forgot to put the linux-kbuild list on Cc, that is probably the
> best place to discuss this patch.
> ---------- Forwarded Message ----------
> Subject: [PATCH] Turn off -Wmaybe-uninitialized when building with -Os
> Date: Thursday 14 March 2013
> From: Arnd Bergmann <arnd at arndb.de>
> To: linux-arch at vger.kernel.org, linux-arm-kernel at lists.infradead.org, linux-kernel at vger.kernel.org
> gcc-4.7 and higher add a lot of false positive warnings about
> potential uses of uninitialized warnings, but only when optimizing
> for size (-Os). This is the default when building allyesconfig,
> which turns on CONFIG_CC_OPTIMIZE_FOR_SIZE.
> In order to avoid getting a lot of patches that initialize such
> variables and accidentally hide real errors along the way, let's
> just turn off this warning on the respective gcc versions
> when building with size optimizations. The -Wmaybe-uninitialized
> option was introduced in the same gcc version (4.7) that is now
> causing the false positives, so there is no effect on older compilers.
> A side effect is that when building with CONFIG_CC_OPTIMIZE_FOR_SIZE,
> we might now see /fewer/ warnings about possibly uninitialized
> warnings than with -O2, but that is still much better than seeing
> warnings known to be bogus.
> Signed-off-by: Arnd Bergmann <arnd at arndb.de>
> Cc: stable at vger.kernel.org
> I'd like to merge this for 3.9 and also for the stable kernels,
> if people agree this is a good idea.
I think I replied to your previous version recently asking whether
this affects real uninitialized variables too.
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