From: "Maciej W. Rozycki" <macro@linux-mips.org>
To: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Tom Herbert <tom@herbertland.com>,
David Miller <davem@davemloft.net>,
Netdev <netdev@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Peter Anvin <hpa@zytor.com>,
the arch/x86 maintainers <x86@kernel.org>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v4 net-next] net: Implement fast csum_partial for x86_64
Date: Mon, 29 Feb 2016 01:39:51 +0000 (GMT) [thread overview]
Message-ID: <alpine.LFD.2.20.1602290135170.28664@eddie.linux-mips.org> (raw)
In-Reply-To: <CAKgT0UfDWXbXSX45XRZjTc6SXz+XqaYa1bHGzOUV_RXSPh=U=A@mail.gmail.com>
On Sun, 28 Feb 2016, Alexander Duyck wrote:
> I actually found the root cause. The problem is in add32_with_carry3.
>
> > +static inline unsigned int add32_with_carry3(unsigned int a, unsigned int b,
> > + unsigned int c)
> > +{
> > + asm("addl %2,%0\n\t"
> > + "adcl %3,%0\n\t"
> > + "adcl $0,%0"
> > + : "=r" (a)
> > + : "" (a), "rm" (b), "rm" (c));
> > +
> > + return a;
> > +}
> > +
>
> You need to set the 'a' input variable attribute to "0" instead of ""
> and then things work for me correctly.
Or alternatively you can reduce the number of operands by one, by using
`"+r" (a)' as output, and then removing `a' as a separate input and
renumbering references to `b' and `c' accordingly. It would IMHO actually
better match the in-place operation as well.
FWIW,
Maciej
next prev parent reply other threads:[~2016-02-29 1:39 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-26 20:03 [PATCH v4 net-next] net: Implement fast csum_partial for x86_64 Tom Herbert
2016-02-26 20:29 ` Linus Torvalds
2016-02-26 20:41 ` Tom Herbert
2016-02-26 22:52 ` Alexander Duyck
2016-02-27 3:11 ` Tom Herbert
2016-02-27 3:40 ` Alexander Duyck
2016-02-27 5:25 ` Linus Torvalds
2016-02-27 8:30 ` Alexander Duyck
2016-02-28 18:56 ` Alexander Duyck
2016-02-28 19:15 ` Tom Herbert
2016-02-29 1:33 ` Alexander Duyck
2016-02-29 1:39 ` Maciej W. Rozycki [this message]
2016-02-28 20:35 ` Eric Dumazet
-- strict thread matches above, loose matches on Subject: below --
2016-02-28 21:43 George Spelvin
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