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From:   Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Wed, 20 Sep 2023 14:20:24 -0500
Message-ID: <CAFUsyfLPLQBs2gQwLDUZHudQrkHSXCcV=Wi0=Znb3gChDZvX2Q@mail.gmail.com>
Subject: Re: x86/csum: Remove unnecessary odd handling
To:     David Laight <David.Laight@aculab.com>
Cc:     "x86@kernel.org" <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "edumazet@google.com" <edumazet@google.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
        "bp@alien8.de" <bp@alien8.de>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
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On Wed, Sep 6, 2023 at 9:38=E2=80=AFAM David Laight <David.Laight@aculab.co=
m> wrote:
>
> From: Noah Goldstein
> > Sent: 01 September 2023 23:21
> ...
> > +     return add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
>
> The generic C alternative:
>         return (temp64 + ror64(temp64, 32)) >> 32;
> is the same number of instructions but might get
> better scheduling.
>
Sorry, I missed this.
Bright idea :)
Adding in new version + you reviewed by tag. Then hopefully this can
get in...

> The C version of csum_fold() from arc/include/asm/checksum.h
> is also better than the x86 asm version.
> (And also pretty much all the other architecture dependant
> copies.)
>
>         David
>
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1=
 1PT, UK
> Registration No: 1397386 (Wales)
>