* Denys Vlasenko <dvlas...@redhat.com> wrote:
> On 05/14/2015 07:08 PM, Linus Torvalds wrote:
> > On Thu, May 14, 2015 at 10:05 AM, Linus Torvalds
> > <torva...@linux-foundation.org> wrote:
> >>
> >> I don't object to the patch, but did we actually confirm that it
> >> always overwrites all of %ecx?
> >
> > Just to clarify: I don't object to the patch because the code
> > doesn't actually end up *depending* on the high bits anyway, and
> > does word-sized compares etc. And the instruction size and speed
> > things I don't doubt. So it's just the commit message I wanted to
> > check wrt that whole "always overwrites all of %ecx". Because
> > older CPU's didn't necessarily (things like partial register
> > writes are much less of an issue when you're in-order and stupid
> > ;)
>
> This is 64-bit code, and all 64-bit CPUs zero-extend moves from
> segment registers. As you said, in this particular code it wouldn't
> matter anyway since subsequent code doesn't care about high bits of
> %ecx...
Mind updating the changelog with all that information? It wasn't
obvious to me either, as most of the mnemonics 'look' 32-bit.
I'd also say that a changelog is not complete, by definition, if Linus
has to ask about it ;-)
Thanks,
Ingo
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