From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: David Laight <David.Laight@ACULAB.COM>
Cc: 'Ard Biesheuvel' <ardb@kernel.org>, Antony Yu <swpenim@gmail.com>,
Nicolas Pitre <nico@fluxnic.net>,
Nick Desaulniers <ndesaulniers@google.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Nathan Chancellor <natechancellor@gmail.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RESEND,PATCH] ARM: fix __div64_32() error when compiling with clang
Date: Mon, 30 Nov 2020 14:18:04 +0000 [thread overview]
Message-ID: <20201130141804.GV1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <ca83a5acdf514169b2fde3ec12ea59fd@AcuMS.aculab.com>
On Mon, Nov 30, 2020 at 01:58:27PM +0000, David Laight wrote:
> > And actually, the same applies on BE, but the other way around. So we
> > should mark __xl as an output register as well, as __xl will assume
> > the right value depending on the endianness.
>
> Why not use "+r" to indicate than an 'output' parameter is also
> used as an input.
>
> Rather cleaner than specifying the same C variable as both
> input and output.
You have an incorrect understanding. "__n" is the input operand in r0.
"__rem" is the output operand in r0/r1.
No single C variable is used as both an input and an output.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
WARNING: multiple messages have this Message-ID (diff)
From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: David Laight <David.Laight@ACULAB.COM>
Cc: Nicolas Pitre <nico@fluxnic.net>, Antony Yu <swpenim@gmail.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Nathan Chancellor <natechancellor@gmail.com>,
'Ard Biesheuvel' <ardb@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RESEND,PATCH] ARM: fix __div64_32() error when compiling with clang
Date: Mon, 30 Nov 2020 14:18:04 +0000 [thread overview]
Message-ID: <20201130141804.GV1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <ca83a5acdf514169b2fde3ec12ea59fd@AcuMS.aculab.com>
On Mon, Nov 30, 2020 at 01:58:27PM +0000, David Laight wrote:
> > And actually, the same applies on BE, but the other way around. So we
> > should mark __xl as an output register as well, as __xl will assume
> > the right value depending on the endianness.
>
> Why not use "+r" to indicate than an 'output' parameter is also
> used as an input.
>
> Rather cleaner than specifying the same C variable as both
> input and output.
You have an incorrect understanding. "__n" is the input operand in r0.
"__rem" is the output operand in r0/r1.
No single C variable is used as both an input and an output.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-11-30 14:19 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-23 7:36 [RESEND,PATCH] ARM: fix __div64_32() error when compiling with clang Antony Yu
2020-11-23 7:36 ` Antony Yu
2020-11-23 18:16 ` Nathan Chancellor
2020-11-23 18:16 ` Nathan Chancellor
2020-11-24 7:42 ` Antony Yu
2020-11-24 10:14 ` Antony Yu
2020-11-24 10:14 ` [RESEND, PATCH] " Antony Yu
2020-11-24 21:06 ` [RESEND,PATCH] " Nick Desaulniers
2020-11-24 21:06 ` [RESEND, PATCH] " Nick Desaulniers
2020-11-30 8:20 ` [PATCH v2] " Antony Yu
2020-11-30 8:20 ` Antony Yu
2020-11-24 23:16 ` [RESEND,PATCH] " kernel test robot
2020-11-24 23:16 ` [RESEND, PATCH] " kernel test robot
2020-11-24 23:16 ` [RESEND,PATCH] " kernel test robot
2020-11-30 10:11 ` Ard Biesheuvel
2020-11-30 10:11 ` [RESEND, PATCH] " Ard Biesheuvel
2020-11-30 10:12 ` [RESEND,PATCH] " Ard Biesheuvel
2020-11-30 10:12 ` [RESEND, PATCH] " Ard Biesheuvel
2020-11-30 10:21 ` [RESEND,PATCH] " Russell King - ARM Linux admin
2020-11-30 10:21 ` Russell King - ARM Linux admin
2020-11-30 10:40 ` Ard Biesheuvel
2020-11-30 10:40 ` [RESEND, PATCH] " Ard Biesheuvel
2020-11-30 13:58 ` [RESEND,PATCH] " David Laight
2020-11-30 13:58 ` David Laight
2020-11-30 14:18 ` Russell King - ARM Linux admin [this message]
2020-11-30 14:18 ` Russell King - ARM Linux admin
2020-11-30 15:50 ` Nicolas Pitre
2020-11-30 15:50 ` Nicolas Pitre
2020-11-30 17:18 ` Ard Biesheuvel
2020-11-30 17:18 ` [RESEND, PATCH] " Ard Biesheuvel
2020-11-30 17:52 ` [RESEND,PATCH] " Nicolas Pitre
2020-11-30 17:52 ` Nicolas Pitre
2020-11-30 18:08 ` Ard Biesheuvel
2020-11-30 18:08 ` [RESEND, PATCH] " Ard Biesheuvel
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