arm: Fix vfp_operand_register for VFP HI regs

[Kyrylo Tkachov]

Hi Christophe,

> -----Original Message-----
> From: Christophe Lyon <christophe.lyon@linaro.org>
> Sent: 03 June 2020 14:30
> To: Kyrylo Tkachov <Kyrylo.Tkachov@arm.com>
> Cc: gcc-patches@gcc.gnu.org
> Subject: Re: arm: Fix vfp_operand_register for VFP HI regs
> 
> Hi,
> 
> 
> On Thu, 14 May 2020 at 17:08, Christophe Lyon
> <christophe.lyon@linaro.org> wrote:
> >
> > On Fri, 1 May 2020 at 12:57, Kyrylo Tkachov <Kyrylo.Tkachov@arm.com>
> wrote:
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Christophe Lyon <christophe.lyon@linaro.org>
> > > > Sent: 30 April 2020 09:51
> > > > To: Kyrylo Tkachov <Kyrylo.Tkachov@arm.com>
> > > > Cc: gcc-patches@gcc.gnu.org
> > > > Subject: Re: arm: Fix vfp_operand_register for VFP HI regs
> > > >
> > > > On Wed, 29 Apr 2020 at 18:40, Kyrylo Tkachov
> <Kyrylo.Tkachov@arm.com>
> > > > wrote:
> > > > >
> > > > > Hi Christophe,
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Gcc-patches <gcc-patches-bounces@gcc.gnu.org> On Behalf
> Of
> > > > > > Christophe Lyon via Gcc-patches
> > > > > > Sent: 29 April 2020 16:53
> > > > > > To: gcc Patches <gcc-patches@gcc.gnu.org>
> > > > > > Subject: arm: Fix vfp_operand_register for VFP HI regs
> > > > > >
> > > > > > Hi,
> > > > > >
> > > > > > While looking at PR target/94743 I noticed an ICE when I tried to
> save
> > > > > > all the FP registers: this was because all HI registers wouldn't match
> > > > > > vfp_register_operand.
> > > > >
> > > > > Hmm, I see that arm_regno_class indeed never returns VFP_REGS and
> > > > would return VFP_HI_REGS here.
> > > > > So the patch looks correct to me.
> > > > > Do you have a testcase for the ICE to add to the testsuite?
> > > > >
> > > >
> > > > No C source code: I found that while extending the list of registers
> > > > pushed in the prologue of an IRQ handler, more-or-less modifying
> > > > arm_save_coproc_regs so that more registers are handled by
> > > > vfp_emit_fstmd.
> > > > The problem occurs when trying to push d16-d31.
> > >
> > > I'd be comfortable taking this now for trunk (GCC 11) so it has time to
> bake.
> > > Once you're ready to post the IRQ handler work we can see about
> backporting this fix it to the branch, if we deem it necessary.
> > > Thanks,
> > > Kyrill
> > >
> >
> > Hi,
> >
> > I've just sent several patches for PR 94743:
> > https://gcc.gnu.org/pipermail/gcc-patches/2020-May/545747.html
> > is v2 of my previous patch: it only emits a warning, and might be
> > sufficient to close the PR, if we decide that
> > we don't want to save the FP registers without explicit user request...
> >
> > Then,
> > [1] https://gcc.gnu.org/pipermail/gcc-patches/2020-May/545748.html
> > [2] https://gcc.gnu.org/pipermail/gcc-patches/2020-May/545749.html
> > are refactorization patches that would make implementing the patch
> > attached here easier.
> >
> > If you apply the attached on top of [1] and [2], you'll notice an ICE
> > fixed by the original patch of this thread.
> >
> > So hopefully applying [1], [2] and the attached should help convince you
> that
> > the vfp_operand_register is OK.
> >
> 
> I've committed [1] and [2] several days ago, so it's now easier to apply
> the patch from
> https://gcc.gnu.org/pipermail/gcc-patches/2020-May/545754.html
> which will trigger an ICE in the new testcases it adds,
> which is fixed by the patch that started this thread:
> https://gcc.gnu.org/pipermail/gcc-patches/2020-April/544877.html

This is okay.
Thanks,
Kyrill

> 
> Is that lalter patch OK?
> 
> Thanks,
> 
> Christophe
> 
> > Thanks
> >
> > > >
> > > >
> > > > > Thanks,
> > > > > Kyrill
> > > > >
> > > > > >
> > > > > > Regression-tested and bootstrapped OK.
> > > > > >
> > > > > > 2020-04-29  Christophe Lyon  <christophe.lyon@linaro.org>
> > > > > >
> > > > > >         gcc/
> > > > > >         * config/arm/predicates.md (vfp_register_operand): Use
> > > > VFP_HI_REGS
> > > > > >         instead of VFP_REGS.
> > > > > >
> > > > > > OK?
> > > > > >
> > > > > > Thanks,
> > > > > >
> > > > > > Christophe