Re: [PATCH] ARM: xor-neon: Replace __GNUC__ checks with CONFIG_CC_IS_GCC

[Nathan Chancellor]

On Fri, May 31, 2019 at 11:03:19PM +0200, Arnd Bergmann wrote:
> On Fri, May 31, 2019 at 10:06 PM 'Nick Desaulniers' via Clang Built
> Linux <clang-built-linux@xxxxxxxxxxxxxxxx> wrote:
> >
> > On Fri, May 31, 2019 at 12:21 PM Arnd Bergmann <arnd@xxxxxxxx> wrote:
> > > clang, I would suggest dropping your patch then, and instead adding
> >
> > I disagree.  The minimum version of gcc required to build the kernel
> > is 4.6, so the comment about older versions of gcc is irrelevant and
> > should be removed.
> 
> Sure, that's ok. It just feels wrong to remove a warning that points
> to a real problem that still exists and can be detected at the moment.
> 
> If we think that clang-9 is going to be fixed before its release,
> the warning could be changed to test for that version as a minimum,
> and point to the bugzilla entry for more details.
> 
>       Arnd

I just tested the arm64 implementation and it shows the same warnings
about cost as arm.

However, I see a warning as something that can be resolved by the user.
The GCC warning's solution is to just use a newer version of GCC
(something fairly easily attainable). This new warning currently has no
solution other than don't use clang.

It is up to you and Nick but I would say unless we are going to
prioritize fixing this, we shouldn't add a warning for it. I'd say it is
more appropriate to fix it then add a warning saying upgrade to this
version to fix it, like the GCC one (though I don't necessarily hate
adding the warning assuming that clang 9 will have it fixed).

Cheers,
Nathan