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SubjectRe: [rc4-amd64] RC4 optimized for AMD64
On Tue, 2 Nov 2004, Denis Vlasenko wrote:

> On Monday 01 November 2004 22:44, dean gaudet wrote:
> > note that
> > p4 would prefer "sub $1, %r11b" here instead of dec... but the difference
> > is likely minimal.
>
> p4 is not the only x86 CPU on the planet. Why should I use
> longer instruction then?

you're asking about spending one byte? one byte extra for code which
could perform better on more CPUs?

i could equally well say "k8 is not the only x86-64 cpu on the planet".

i really don't care whether this change is made or not, i only mentioned a
general perf rule.

go ahead and use -Os for the rest of the kernel if you're worried about
size, it'll likely go faster. but spending 1 byte in code which is perf
critical is nothing.

-dean
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