On Tue, Mar 01, 2022 at 11:41:06AM +, David Laight wrote:
> From: Christophe Leroy
> > Sent: 01 March 2022 11:15
> ...
> > Looks like ARM also does better code with the generic implementation as
> > it seems to have some looking like conditional instructions 'rorne' and
> > 'strne'.
>
> In
From: Christophe Leroy
> Sent: 01 March 2022 11:15
...
> Looks like ARM also does better code with the generic implementation as
> it seems to have some looking like conditional instructions 'rorne' and
> 'strne'.
In arm32 (and I think arm64) every instruction is conditional.
> static
Le 01/03/2022 à 11:47, David Laight a écrit :
> From: Christophe Leroy
>> Sent: 01 March 2022 10:20
>>
>> Le 13/02/2022 à 18:47, David Laight a écrit :
>>> From: Segher Boessenkool
Sent: 13 February 2022 09:16
>>>
> What happens on x86-64?
>
> Trying to do the same in
From: Christophe Leroy
> Sent: 01 March 2022 10:20
>
> Le 13/02/2022 à 18:47, David Laight a écrit :
> > From: Segher Boessenkool
> >> Sent: 13 February 2022 09:16
> >
> >>
> >>> What happens on x86-64?
> >>>
> >>> Trying to do the same in the x86 ipcsum code tended to make the code
> >>>
Le 13/02/2022 à 18:47, David Laight a écrit :
> From: Segher Boessenkool
>> Sent: 13 February 2022 09:16
>
>>
>>> What happens on x86-64?
>>>
>>> Trying to do the same in the x86 ipcsum code tended to make the code worse.
>>> (Although that test is for an odd length fragment and can just be
On Sun, Feb 13, 2022 at 05:47:52PM +, David Laight wrote:
> From: Segher Boessenkool
> > Sent: 13 February 2022 09:16
> > In an ideal world the compiler could choose the optimal code sequences
> > everywhere. But that won't ever happen, the search space is way too
> > big. So compilers just
From: Segher Boessenkool
> Sent: 13 February 2022 09:16
>
> > What happens on x86-64?
> >
> > Trying to do the same in the x86 ipcsum code tended to make the code worse.
> > (Although that test is for an odd length fragment and can just be removed.)
>
> In an ideal world the compiler could
On Sun, Feb 13, 2022 at 02:39:06AM +, David Laight wrote:
> From: Christophe Leroy
> > Sent: 11 February 2022 08:48
> >
> > Today's implementation of csum_shift() leads to branching based on
> > parity of 'offset'
> >
> > 02f8 :
> > 2f8: 70 a5 00 01 andi. r5,r5,1
From: Christophe Leroy
> Sent: 11 February 2022 08:48
>
> Today's implementation of csum_shift() leads to branching based on
> parity of 'offset'
>
> 02f8 :
>2f8: 70 a5 00 01 andi. r5,r5,1
>2fc: 41 a2 00 08 beq 304
>300:
