On Thu, Jan 16, 2020 at 07:57:29AM -0600, Segher Boessenkool wrote:
> On Thu, Jan 16, 2020 at 09:06:08AM +0100, Gabriel Paubert wrote:
> > On Thu, Jan 16, 2020 at 07:11:36AM +0100, Christophe Leroy wrote:
> > > Hi Segher,
> > >
> > > I'm trying to see if we could enhance TCP checksum calculations
> You mean the mpc8xx , but I'm also using the mpc832x which has a e300c2
> core and is capable of executing 2 insns in parallel if not in the same
> Unit.
That should let you do a memory read and an add.
(I can't remember if the ppc has 'add from memory' but that is
likely to use both units anywa
Le 16/01/2020 à 17:21, Segher Boessenkool a écrit :
Christophe uses a very primitive 32-bit cpu, not even superscalar. A
loop doing adde is pretty much optimal, probably wants some unrolling
though.
You mean the mpc8xx , but I'm also using the mpc832x which has a e300c2
core and is capable
From: Segher Boessenkool
> Sent: 16 January 2020 16:22
...
> > However a loop of 'add with carry' instructions may not be the
> > fastest code by any means.
> > Because the carry flag is needed for every 'adc' you can't do more
> > that one adc per clock.
> > This limits you to 8 bytes/clock on a 6
Hi!
On Thu, Jan 16, 2020 at 03:54:58PM +, David Laight wrote:
> if you are trying to 'loop carry' the 'carry flag' with 'add with carry'
> instructions you'll almost certainly need to write the loop in asm.
> Since the loop itself is simple, this probably doesn't matter.
Agreed.
> However a
From: Christophe Leroy
> Sent: 16 January 2020 06:12
>
> I'm trying to see if we could enhance TCP checksum calculations by
> splitting inline assembly blocks to give GCC the opportunity to mix it
> with other stuff, but I'm getting difficulties with the carry.
if you are trying to 'loop carry' t
Hi!
On Thu, Jan 16, 2020 at 07:11:36AM +0100, Christophe Leroy wrote:
> I'm trying to see if we could enhance TCP checksum calculations by
> splitting inline assembly blocks to give GCC the opportunity to mix it
> with other stuff, but I'm getting difficulties with the carry.
>
> As far as I ca
On Thu, Jan 16, 2020 at 09:06:08AM +0100, Gabriel Paubert wrote:
> On Thu, Jan 16, 2020 at 07:11:36AM +0100, Christophe Leroy wrote:
> > Hi Segher,
> >
> > I'm trying to see if we could enhance TCP checksum calculations by splitting
> > inline assembly blocks to give GCC the opportunity to mix it
On Thu, Jan 16, 2020 at 07:11:36AM +0100, Christophe Leroy wrote:
> Hi Segher,
>
> I'm trying to see if we could enhance TCP checksum calculations by splitting
> inline assembly blocks to give GCC the opportunity to mix it with other
> stuff, but I'm getting difficulties with the carry.
>
> As fa
