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Date: Wed, 30 May 2018 03:27:39 -0500
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Simon Guo <wei.guo.simon@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org,
 "Naveen N.  Rao" <naveen.n.rao@linux.vnet.ibm.com>,
 Cyril Bur <cyrilbur@gmail.com>
Subject: Re: [PATCH v6 1/4] powerpc/64: Align bytes before fall back to
 .Lshort in powerpc64 memcmp()
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Hi!

On Wed, May 30, 2018 at 04:11:50PM +0800, Simon Guo wrote:
> On Mon, May 28, 2018 at 05:35:12AM -0500, Segher Boessenkool wrote:
> > On Fri, May 25, 2018 at 12:07:33PM +0800, wei.guo.simon@gmail.com wrote:
> > If this doesn't use cr0 anymore, you can do  rlwinm r6,r6,0,7  instead of
> > andi r6,r6,7 .
> > 
> CR0 is used at .Lno_short handling.

Tricky.

> > > +	subfc.	r5,r6,r5
> > 
> > Why subfc?  You don't use the carry.
> OK. I will use subfc instead.

I meant subf -- no carry.  If you want CR0 set there is subf. just fine.

> > > +	bgt	cr0,8f
> > > +	li	r3,-1
> > > +8:
> > > +	blr
> > 
> >   blelr
> >   li r3,-1
> >   blr
> Sure. That looks more impact.

Should have been bgtlr of course -- well check please :-)


Segher