On Tue, Nov 30, 2004 at 12:05:51PM -0500, William M. Quarles wrote:
this case irrelevant instruction set), I'd really like to see
that
performance difference. Now were you saying that this cmov is part of
i486 or i686? I'd like to try rebuilding everything to see if it makes
a difference.
cmov is an optional instruction for i686 - it turns up on the PPro, PII, PIII,
PIV and Pentium M at least. By PIV its as slow or slower than not using it.
Is the advantage still there, or is it just no longer a significant
advantage? Or is it a cost? Unless it's a cost, I don't see what's
wrong with putting in the advantage, unless it's a lot more work on your
part. Is it more work?
Its a cost because some processors we support today lack this instruction but
are otherwise 686.
Alan