From: Simon Guo <wei.guo.simon@gmail•com>
To: Segher Boessenkool <segher@kernel•crashing.org>
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 2/4] powerpc/64: enhance memcmp() with VMX instruction for long bytes comparision
Date: Wed, 30 May 2018 17:03:21 +0800 [thread overview]
Message-ID: <20180530090321.GE5951@simonLocalRHEL7.x64> (raw)
In-Reply-To: <20180530083540.GG17342@gate.crashing.org>
On Wed, May 30, 2018 at 03:35:40AM -0500, Segher Boessenkool wrote:
> On Wed, May 30, 2018 at 04:14:02PM +0800, Simon Guo wrote:
> > Hi Segher,
> > On Mon, May 28, 2018 at 06:05:59AM -0500, Segher Boessenkool wrote:
> > > On Fri, May 25, 2018 at 12:07:34PM +0800, wei.guo.simon@gmail•com wrote:
> > > > + /* save and restore cr0 */
> > > > + mfocrf r5,64
> > > > + EXIT_VMX_OPS
> > > > + mtocrf 64,r5
> > > > + b .LcmpAB_lightweight
> > >
> > > That's cr1, not cr0. You can use mcrf instead, it is cheaper (esp. if
> > > you have it in a non-volatile CR field before so you need only one, if any).
> > >
> > You are right :) How about using mtcr/mfcr instead, I think they are
> > fast as well and more readable.
>
> Those are much worse than m[ft]ocrf.
>
> You probably should just shuffle things around so that EXIT_VMX_OPS
> does not clobber the CR field you need to keep.
Let me use mcrf then :)
Thanks,
- Simon
next prev parent reply other threads:[~2018-05-30 9:03 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-25 4:07 [PATCH v6 0/4] powerpc/64: memcmp() optimization wei.guo.simon
2018-05-25 4:07 ` [PATCH v6 1/4] powerpc/64: Align bytes before fall back to .Lshort in powerpc64 memcmp() wei.guo.simon
2018-05-28 10:35 ` Segher Boessenkool
2018-05-30 8:11 ` Simon Guo
2018-05-30 8:27 ` Segher Boessenkool
2018-05-30 9:02 ` Simon Guo
2018-05-25 4:07 ` [PATCH v6 2/4] powerpc/64: enhance memcmp() with VMX instruction for long bytes comparision wei.guo.simon
2018-05-28 11:05 ` Segher Boessenkool
2018-05-30 8:14 ` Simon Guo
2018-05-30 8:35 ` Segher Boessenkool
2018-05-30 9:03 ` Simon Guo [this message]
2018-06-06 6:42 ` Simon Guo
2018-06-06 20:00 ` Segher Boessenkool
2018-05-28 11:59 ` Michael Ellerman
2018-05-30 8:15 ` Simon Guo
2018-05-25 4:07 ` [PATCH v6 3/4] powerpc/64: add 32 bytes prechecking before using VMX optimization on memcmp() wei.guo.simon
2018-05-25 4:07 ` [PATCH v6 4/4] powerpc:selftest update memcmp_64 selftest for VMX implementation wei.guo.simon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180530090321.GE5951@simonLocalRHEL7.x64 \
--to=wei.guo.simon@gmail$(echo .)com \
--cc=cyrilbur@gmail$(echo .)com \
--cc=linuxppc-dev@lists$(echo .)ozlabs.org \
--cc=naveen.n.rao@linux$(echo .)vnet.ibm.com \
--cc=segher@kernel$(echo .)crashing.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox