Messages in this thread | | | Date | Tue, 2 Nov 2004 10:52:12 -0800 (PST) | From | dean gaudet <> | Subject | Re: [rc4-amd64] RC4 optimized for AMD64 |
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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.
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