From: Juergen Christ <jchrist@linux.ibm.com>
To: Heiko Carstens <hca@linux.ibm.com>
Cc: Nathan Chancellor <nathan@kernel.org>,
Miguel Ojeda <ojeda@kernel.org>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
Sven Schnelle <svens@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>
Subject: Re: [PATCH 3/3] s390/bitops: Remove volatile qualifier from flogr() inline assembly
Date: Thu, 11 Sep 2025 09:45:01 +0200 [thread overview]
Message-ID: <b326445d-0aec-44af-95f0-143dda6e635c-jchrist@linux.ibm.com> (raw)
In-Reply-To: <20250910151216.646600-4-hca@linux.ibm.com>
> The flogr() inline assembly has no side effects and generates the same
> output if the input does not change. Therefore remove the volatile
> qualifier to allow the compiler to optimize the inline assembly away,
> if possible.
>
> This also removes the superfluous '\n' which makes the inline assembly
> appear larger than it is according to compiler heuristics (number of
> lines).
>
> Suggested-by: Juergen Christ <jchrist@linux.ibm.com>
> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
prev parent reply other threads:[~2025-09-11 7:45 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-10 15:12 [PATCH 0/3] s390: Fix and optimize __flogr() " Heiko Carstens
2025-09-10 15:12 ` [PATCH 1/3] Compiler Attributes: Add __assume macro Heiko Carstens
2025-09-11 1:32 ` Nathan Chancellor
2025-09-11 14:56 ` Heiko Carstens
2025-09-11 18:44 ` Nathan Chancellor
2025-09-11 19:04 ` Miguel Ojeda
2025-09-11 20:42 ` Nathan Chancellor
2025-09-11 18:56 ` Miguel Ojeda
2025-09-11 18:59 ` Miguel Ojeda
2025-09-12 10:25 ` Heiko Carstens
2025-09-10 15:12 ` [PATCH 2/3] s390/bitops: Limit return value range of __flogr() Heiko Carstens
2025-09-11 7:44 ` Juergen Christ
2025-09-11 13:24 ` kernel test robot
2025-09-10 15:12 ` [PATCH 3/3] s390/bitops: Remove volatile qualifier from flogr() inline assembly Heiko Carstens
2025-09-11 7:45 ` Juergen Christ [this message]
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