From: Jeremy Linton <jeremy.linton@arm.com>
To: Mark Rutland <mark.rutland@arm.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org, gcc@gcc.gnu.org,
catalin.marinas@arm.com, will@kernel.org, marcan@marcan.st,
maz@kernel.org, szabolcs.nagy@arm.com, f.fainelli@gmail.com,
opendmb@gmail.com, Andrew Pinski <pinskia@gmail.com>,
Ard Biesheuvel <ardb@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
x86@kernel.org, andrew.cooper3@citrix.com
Subject: Re: GCC 12 miscompilation of volatile asm (was: Re: [PATCH] arm64/io: Remind compiler that there is a memory side effect)
Date: Mon, 11 Apr 2022 14:02:46 -0500 [thread overview]
Message-ID: <b98efe11-a11e-5787-49a7-c151efdf9401@arm.com> (raw)
In-Reply-To: <YlQDfC+J8BXHcvpk@FVFF77S0Q05N>
Hi,
On 4/11/22 05:31, Mark Rutland wrote:
> On Tue, Apr 05, 2022 at 01:51:30PM +0100, Mark Rutland wrote:
>> Hi all,
>>
>> [adding kernel folk who work on asm stuff]
>>
>> As a heads-up, GCC 12 (not yet released) appears to erroneously optimize away
>> calls to functions with volatile asm. Szabolcs has raised an issue on the GCC
>> bugzilla:
>>
>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105160
>>
>> ... which is a P1 release blocker, and is currently being investigated.
>
> Jan Hubicka fixed this in GCC commit:
>
> aabb9a261ef060cf ("Propagate nondeterministic and side_effects flags in modref summary after inlining")
>
> ... and all my local tests look good with that applied.
>
> Compiler explorer's trunk build now has that fix, so the examples from before
> now look good:
>
> aarch64: https://godbolt.org/z/vMczqjYvs
>
> x86_64: https://godbolt.org/z/cveff9hq5
>
> Jeremy, now that the real issue has been identified and fixed, I assume you'll
> send a revert for commit:
>
> 8d3ea3d402db94b6 ("net: bcmgenet: Use stronger register read/writes to assure ordering")
>
> ... ?
Yes, that's the plan.
Thanks,
prev parent reply other threads:[~2022-04-11 19:03 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-01 16:44 [PATCH] arm64/io: Remind compiler that there is a memory side effect Jeremy Linton
2022-04-01 17:22 ` Mark Rutland
2022-04-03 7:36 ` Andrew Pinski
2022-04-03 7:47 ` Ard Biesheuvel
2022-04-03 7:47 ` Ard Biesheuvel
2022-04-04 9:14 ` Will Deacon
2022-04-03 17:40 ` Doug Berger
2022-04-05 12:51 ` GCC 12 miscompilation of volatile asm (was: Re: [PATCH] arm64/io: Remind compiler that there is a memory side effect) Mark Rutland
2022-04-05 13:04 ` Mark Rutland
2022-04-05 13:20 ` Andrew Cooper
2022-04-05 14:05 ` Peter Zijlstra
2022-04-11 10:22 ` Mark Rutland
2022-04-11 10:31 ` Mark Rutland
2022-04-11 19:02 ` Jeremy Linton [this message]
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