Re: x86/csum: Remove unnecessary odd handling

From: Noah Goldstein
Date: Wed Sep 20 2023 - 15:20:42 EST


On Wed, Sep 6, 2023 at 9:38 AM David Laight <David.Laight@xxxxxxxxxx> 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)
>