Messages in this thread | | | From | <> | Subject | Re: .../asm-i386/bitops.h performance improvements | Date | Wed, 15 Jun 2005 19:48:29 -0400 |
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The only thing I've seen so far that loses is a straight original 486. Its pipe is somewhat more simple minded and interlock prone than later models. PPro, K6 and 386SX are big winners.
On the 386's, lacking actual pipeline, the compactness of the LEA over the SHL/ADD can be more of an overriding factor.
----- Original Message ----- From: "Maciej W. Rozycki" <macro@linux-mips.org> To: <cutaway@bellsouth.net> Cc: <linux-kernel@vger.kernel.org> Sent: Wednesday, June 15, 2005 11:34 Subject: Re: .../asm-i386/bitops.h performance improvements
> > Be careful about model-specific penalties from using certain address > modes and AGIs when using "lea" for such calculations. > > Maciej
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