Ping: [PATCH][Arm] Enable MVE SIMD modes for vectorization

[Kyrylo Tkachov]

Hi Christophe,

> -----Original Message-----
> From: Gcc-patches <gcc-patches-bounces@gcc.gnu.org> On Behalf Of
> Christophe Lyon via Gcc-patches
> Sent: 12 October 2020 12:41
> To: Dennis Zhang <Dennis.Zhang@arm.com>
> Cc: Richard Earnshaw <Richard.Earnshaw@arm.com>; nd <nd@arm.com>;
> gcc-patches@gcc.gnu.org; Ramana Radhakrishnan
> <Ramana.Radhakrishnan@arm.com>
> Subject: Re: Ping: [PATCH][Arm] Enable MVE SIMD modes for vectorization
> 
> Hi,
> 
> 
> On Thu, 8 Oct 2020 at 16:22, Christophe Lyon <christophe.lyon@linaro.org>
> wrote:
> >
> > On Thu, 8 Oct 2020 at 16:08, Dennis Zhang <dennis.zhang@arm.com>
> wrote:
> > >
> > > Hi Christophe,
> > >
> > > On 08/10/2020 14:14, Christophe Lyon wrote:
> > > > Hi,
> > > >
> > > >
> > > > On Tue, 6 Oct 2020 at 15:37, Dennis Zhang via Gcc-patches
> > > > <gcc-patches@gcc.gnu.org> wrote:
> > > >>
> > > >> On 9/16/20 4:00 PM, Dennis Zhang wrote:
> > > >>> Hi all,
> > > >>>
> > > >>> This patch enables SIMD modes for MVE auto-vectorization.
> > > >>> In this patch, the integer and float MVE SIMD modes are returned by
> > > >>> arm_preferred_simd_mode
> (TARGET_VECTORIZE_PREFERRED_SIMD_MODE hook) when
> > > >>> MVE or MVE_FLOAT is enabled.
> > > >>> Then the expanders for auto-vectorization can be used for
> generating MVE
> > > >>> SIMD code.
> > > >>>
> > > >>> This patch also fixes bugs in MVE vreiterpretq_*.c tests which are
> > > >>> revealed by the enabled MVE SIMD modes.
> > > >>> The tests are for checking the MVE reinterpret intrinsics.
> > > >>> There are two functions in each of the tests. The two functions
> contain
> > > >>> the pattern of identical code so that they are folded in icf pass.
> > > >>> Because of icf, the instruction count only checks one function which
> is 8.
> > > >>> However when the SIMD modes are enabled, the estimation of the
> code size
> > > >>> becomes smaller so that inlining is applied after icf, then the
> > > >>> instruction count becomes 16 which causes failure of the tests.
> > > >>> Because the icf is not the expected pattern to be tested but causes
> > > >>> above issues, -fno-ipa-icf is applied to the tests to avoid unstable
> > > >>> instruction count.
> > > >>>
> > > >>> This patch is separated from
> > > >>> https://gcc.gnu.org/pipermail/gcc-patches/2020-
> August/552104.html
> > > >>> because this part is not strongly connected to the aim of that one so
> > > >>> that causing confusion.
> > > >>>
> > > >>> Regtested and bootstraped.
> > > >>>
> > > >>> Is it OK for trunk please?
> > > >>>
> > > >>> Thanks
> > > >>> Dennis
> > > >>>
> > > >>> gcc/ChangeLog:
> > > >>>
> > > >>> 2020-09-15  Dennis Zhang  <dennis.zhang@arm.com>
> > > >>>
> > > >>>        * config/arm/arm.c (arm_preferred_simd_mode): Enable MVE
> SIMD modes.
> > > >>>
> > > >
> > > > Since toolchain builds work again after Jakub's divmod fix, I'm now
> > > > facing another build error likely caused by this patch:
> > > > In file included from
> > > > /tmp/2601185_2.tmpdir/aci-gcc-fsf/sources/gcc-
> fsf/gccsrc/gcc/coretypes.h:449:0,
> > > >                   from
> > > > /tmp/2601185_2.tmpdir/aci-gcc-fsf/sources/gcc-
> fsf/gccsrc/gcc/config/arm/arm.c:28:
> > > > /tmp/2601185_2.tmpdir/aci-gcc-fsf/sources/gcc-
> fsf/gccsrc/gcc/config/arm/arm.c:
> > > > In function 'machine_mode arm_preferred_simd_mode(scalar_mode)':
> > > > ./insn-modes.h:196:71: error: temporary of non-literal type
> > > > 'scalar_int_mode' in a constant expression
> > > >   #define QImode (scalar_int_mode ((scalar_int_mode::from_int)
> E_QImode))
> > > >                                                                         ^
> > > > /tmp/2601185_2.tmpdir/aci-gcc-fsf/sources/gcc-
> fsf/gccsrc/gcc/config/arm/arm.c:28970:12:
> > > > note: in expansion of macro 'QImode'
> > > >         case QImode:
> > > >
> > > > and similarly for the other cases.
> > > >
> > > > Does the build work for you?
> > > >
> > > > Thanks,
> > > >
> > > > Christophe
> > > >
> > >
> > > Thanks for the report. Sorry to see the error.
> > > I tested it for arm-none-eabi and arm-none-linux-gnueabi targets. I
> > > didn't get this error.
> > > Could you please help to show the configuration you use for your build?
> > > I will test and fix at once.
> > >
> >
> > It fails on all of them for me. Does it work for you with current
> > master? (r11-3720-gf18eeb6b958acd5e1590ca4a73231486b749be9b)
> >
> 
> So... I guess you are using a host with GCC more recent than 4.8.5? :-)
> When I build manually on ubuntu-16.04 with gcc-5.4, the build succeeds,
> and after manually building with the same environment in the compute
> farm I use for validation (RHEL 7, gcc-4.8.5), I managed to reproduce the
> build failure.
> It's a matter of replacing
> case QImode:
> with
> case E_QImode:
> 
> Is the attached patch OK? Or do we instead want to revisit the minimum
> gcc version required to build gcc?

I'd rather go with this patch as long as it passes the usual testing.
Thanks,
Kyrill

> 
> Thanks,
> 
> Christophe
> 
> 
> > > Thanks
> > > Dennis