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Re: i486 base architecture



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


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