i386-class support changed in F-13?

[Richard W.M. Jones]

On Wed, Jun 02, 2010 at 12:11:26PM -0400, David Michael wrote:
> Hi,
> 
> On Wed, Jun 2, 2010 at 11:42 AM, Richard W.M. Jones <rjones at redhat.com> wrote:
> > I wonder what the performance impact is.  NOPL appears to be a
> > variable length NOP (no-op).  Obviously a very useful instruction for
> > things like alignment, and gcc seems to stuff lots of them into the
> > code:
> >
> >  $ objdump -d /bin/ls | wc -l
> >  16867
> >  $ objdump -d /bin/ls | grep nopl | wc -l
> >  369
> >
> >  369/16867 ~ 2%
> >
> > This is not a very fair comparison because we'd want to know how
> > frequently NOPL is executed, but I hope it shows that these
> > instructions are not infrequent.
> 
>   I recall checking this when F12 was declared to go i686 but retain
> support for Geode LX CPUs.  NOPLs were common in x86_64, but seemed to
> be very infrequent in 32-bit land (which is what would run on a Geode
> anyway).
> 
>   To see if this is still the case, I downloaded and extracted F13's
> 32-bit coreutils, and no binary appears to contain a single NOPL.
> (Though I get a similar result as your test with x86_64.)
> 
> objdump -d {,usr/}{,s}bin/* | grep -Fc nopl
> 0

Ah very true.  I was forgetting that they were 32 bit.

(I even *have* one of them :-)

Rich.

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