From: Ramana Radhakrishnan <ramana.gcc@googlemail.com>
To: Richard Earnshaw <Richard.Earnshaw@foss.arm.com>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>,
Richard Earnshaw <Richard.Earnshaw@arm.com>,
Alex Coplan <alex.coplan@arm.com>
Subject: Re: [Patch Arm] Fix PR 92999
Date: Thu, 17 Nov 2022 20:15:18 +0000 [thread overview]
Message-ID: <CAJA7tRZvFjcetrD5otbcw7MG-2UyJHhFZDc7jRrqr=fjV1fJtQ@mail.gmail.com> (raw)
In-Reply-To: <CAJA7tRYadtzpCG8ehT5DVvHR9_BPFh7ZURwftwdqzYhHS6XLtw@mail.gmail.com>
On Fri, Nov 11, 2022 at 9:50 PM Ramana Radhakrishnan
<ramana.gcc@googlemail.com> wrote:
>
> On Thu, Nov 10, 2022 at 7:46 PM Ramana Radhakrishnan
> <ramana.gcc@googlemail.com> wrote:
> >
> > On Thu, Nov 10, 2022 at 6:03 PM Richard Earnshaw
> > <Richard.Earnshaw@foss.arm.com> wrote:
> > >
> > >
> > >
> > > On 10/11/2022 17:21, Richard Earnshaw via Gcc-patches wrote:
> > > >
> > > >
> > > > On 08/11/2022 18:20, Ramana Radhakrishnan via Gcc-patches wrote:
> > > >> PR92999 is a case where the VFP calling convention does not allocate
> > > >> enough FP registers for a homogenous aggregate containing FP16 values.
> > > >> I believe this is the complete fix but would appreciate another set of
> > > >> eyes on this.
> > > >>
> > > >> Could I get a hand with a regression test run on an armhf environment
> > > >> while I fix my environment ?
> > > >>
> > > >> gcc/ChangeLog:
> > > >>
> > > >> PR target/92999
> > > >> * config/arm/arm.c (aapcs_vfp_allocate_return_reg): Adjust to handle
> > > >> aggregates with elements smaller than SFmode.
> > > >>
> > > >> gcc/testsuite/ChangeLog:
> > > >>
> > > >> * gcc.target/arm/pr92999.c: New test.
> > > >>
> > > >>
> > > >> Thanks,
> > > >> Ramana
> > > >>
> > > >> Signed-off-by: Ramana Radhakrishnan <ramana.gcc@gmail.com>
> > > >
> > > > I'm not sure about this. The AAPCS does not mention a base type of a
> > > > half-precision FP type as an appropriate homogeneous aggregate for using
> > > > VFP registers for either calling or returning.
> >
> > Ooh interesting, thanks for taking a look and poking at the AAPCS and
> > that's a good catch. BF16 should also have the same behaviour as FP16
> > , I suspect ?
>
> I suspect I got caught out by the definition of the Homogenous
> aggregate from Section 5.3.5
> ((https://github.com/ARM-software/abi-aa/blob/2982a9f3b512a5bfdc9e3fea5d3b298f9165c36b/aapcs32/aapcs32.rst#homogeneous-aggregates)
> which simply suggests it's an aggregate of fundamental types which
> lists half precision floating point .
>
> FTR, ideally I should have read 7.1.2.1
> https://github.com/ARM-software/abi-aa/blob/2982a9f3b512a5bfdc9e3fea5d3b298f9165c36b/aapcs32/aapcs32.rst#procedure-calling)
> :)
>
>
>
> >
> > > >
> > > > So perhaps the bug is that we try to treat this as a homogeneous
> > > > aggregate at all.
> >
> > Yep I agree - I'll take a look again tomorrow and see if I can get a fix.
> >
> > (And thanks Alex for the test run, I might trouble you again while I
> > still (slowly) get some of my boards back up)
>
>
> and as promised take 2. I'd really prefer another review on this one
> to see if I've not missed anything in the cases below.
Ping ?
Ramana
>
> regards
> Ramana
>
>
> >
> > regards,
> > Ramana
> >
> >
> > >
> > > R.
next prev parent reply other threads:[~2022-11-17 20:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-08 18:20 Ramana Radhakrishnan
2022-11-09 18:42 ` Alex Coplan
2022-11-10 17:21 ` Richard Earnshaw
2022-11-10 18:03 ` Richard Earnshaw
2022-11-10 19:46 ` Ramana Radhakrishnan
2022-11-11 21:50 ` Ramana Radhakrishnan
2022-11-17 20:15 ` Ramana Radhakrishnan [this message]
2022-11-24 12:32 ` Ramana Radhakrishnan
2022-11-24 16:12 ` Richard Earnshaw
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