From: Heiko Carstens <hca@linux.ibm.com>
To: Nathan Chancellor <nathan@kernel.org>,
Miguel Ojeda <ojeda@kernel.org>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Juergen Christ <jchrist@linux.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
Sven Schnelle <svens@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>
Subject: [PATCH 0/3] s390: Fix and optimize __flogr() inline assembly
Date: Wed, 10 Sep 2025 17:12:13 +0200 [thread overview]
Message-ID: <20250910151216.646600-1-hca@linux.ibm.com> (raw)
A recent optimization of the s390 specific ffs() and ffs64()
implementations leads to a new compiler warning. Instead of reverting the
optimization address this with the rather new assume attribute, which
generates even better code, if supported by compilers.
Since the assume attribute may be useful for others as well, add the
__assume macro to compiler attributes, so it is kernel wide available,
instead of adding an s390 specific optimization.
Heiko Carstens (3):
Compiler Attributes: Add __assume macro
s390/bitops: Limit return value range of __flogr()
s390/bitops: Remove volatile qualifier from flogr() inline assembly
arch/s390/include/asm/bitops.h | 16 +++++++++-------
include/linux/compiler_attributes.h | 16 ++++++++++++++++
2 files changed, 25 insertions(+), 7 deletions(-)
--
2.48.1
next reply other threads:[~2025-09-10 15:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-10 15:12 Heiko Carstens [this message]
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
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