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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Thu, 15 Jun 2023 16:48:22 -0400
Message-ID: <CAKwvOd=uqfnyw2u=Nhm+Q0uGORjW9GB+pso6tb_HKGSU0rhZBQ@mail.gmail.com>
Subject: Re: lib/test_bitmap.c:920:2: error: call to '__compiletime_assert_239'
 declared with 'error' attribute: BUILD_BUG_ON failed: !__builtin_constant_p(res)
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     kernel test robot <lkp@intel.com>,
        Alexander Lobakin <alexandr.lobakin@intel.com>,
        llvm@lists.linux.dev, oe-kbuild-all@lists.linux.dev,
        linux-kernel@vger.kernel.org, Yury Norov <yury.norov@gmail.com>
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On Thu, Jun 15, 2023 at 3:52=E2=80=AFPM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Thu, Jun 15, 2023 at 7:22=E2=80=AFAM Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> >
> > On Thu, Jun 15, 2023 at 02:32:02PM +0800, kernel test robot wrote:
> > > Hi Alexander,
> > >
> > > FYI, the error/warning still remains.
> > >
> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linu=
x.git master
> > > head:   b6dad5178ceaf23f369c3711062ce1f2afc33644
> > > commit: dc34d5036692c614eef23c1130ee42a201c316bf lib: test_bitmap: ad=
d compile-time optimization/evaluations assertions
> > > date:   12 months ago
> > > config: arm64-randconfig-r025-20230615 (https://download.01.org/0day-=
ci/archive/20230615/202306151433.QKcn7ZNn-lkp@intel.com/config)
>
> ^ randconfig
>
> > > compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.=
git ae42196bc493ffe877a7e3dff8be32035dea4d07)
> > > reproduce (this is a W=3D1 build):
> > >         mkdir -p ~/bin
> > >         wget https://raw.githubusercontent.com/intel/lkp-tests/master=
/sbin/make.cross -O ~/bin/make.cross
> > >         chmod +x ~/bin/make.cross
> > >         # install arm64 cross compiling tool for clang build
> > >         # apt-get install binutils-aarch64-linux-gnu
> > >         # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/li=
nux.git/commit/?id=3Ddc34d5036692c614eef23c1130ee42a201c316bf
> > >         git remote add linus https://git.kernel.org/pub/scm/linux/ker=
nel/git/torvalds/linux.git
> > >         git fetch --no-tags linus master
> > >         git checkout dc34d5036692c614eef23c1130ee42a201c316bf
> > >         # save the config file
> > >         mkdir build_dir && cp config build_dir/.config
> > >         COMPILER_INSTALL_PATH=3D$HOME/0day COMPILER=3Dclang ~/bin/mak=
e.cross W=3D1 O=3Dbuild_dir ARCH=3Darm64 olddefconfig
> > >         COMPILER_INSTALL_PATH=3D$HOME/0day COMPILER=3Dclang ~/bin/mak=
e.cross W=3D1 O=3Dbuild_dir ARCH=3Darm64 SHELL=3D/bin/bash lib/
> > >
> > > If you fix the issue in a separate patch/commit (i.e. not just a new =
version of
> > > the same patch/commit), kindly add following tags
> > > | Reported-by: kernel test robot <lkp@intel.com>
> > > | Closes: https://lore.kernel.org/oe-kbuild-all/202306151433.QKcn7ZNn=
-lkp@intel.com/
> > >
> > > All errors (new ones prefixed by >>):
> >
> > >    888                /*
> > >    889                 * Equals to `unsigned long bitmap[1] =3D { GEN=
MASK(6, 5), }`.
> > >    890                 * Clang on s390 optimizes bitops at compile-ti=
me as intended, but at
> > >    891                 * the same time stops treating @bitmap and @bi=
topvar as compile-time
> > >    892                 * constants after regular test_bit() is execut=
ed, thus triggering the
> > >    893                 * build bugs below. So, call const_test_bit() =
there directly until
> > >    894                 * the compiler is fixed.
> > >    895                 */
> > >    896                bitmap_clear(bitmap, 0, BITS_PER_LONG);
> > >    897        #if defined(__s390__) && defined(__clang__)
> > >    898                if (!const_test_bit(7, bitmap))
> > >    899        #else
> > >    900                if (!test_bit(7, bitmap))
> > >    901        #endif
> >
> > Hmm... Reveals the bug in clang/arm64?
>
> Seems related to the config.  ARCH=3Darm64 defconfig +
> CONFIG_TEST_BITMAP=3Dy doesn't trigger this for me, but the randconfig
> does.  We'll bisect the config, and update the thread tracking this:
> https://github.com/ClangBuiltLinux/linux/issues/1874

KASAN and GCOV together seem to be tickling this.

>
> >
> > >    919                res =3D !test_bit(18, &bitopvar);
> > >  > 920                BUILD_BUG_ON(!__builtin_constant_p(res));
> > >    921                BUILD_BUG_ON(!res);
> >
> >
> > --
> > With Best Regards,
> > Andy Shevchenko
> >
> >
> >
>
>
> --
> Thanks,
> ~Nick Desaulniers


--=20
Thanks,
~Nick Desaulniers