From: Matthew Miller mattdm@mattdm.org

I think it goes something like this: "Bu.... bigger number... bigger number faster! Want bigger number!" :)

Never confuse marketing with actual ISA compatibility and optimization.

Consider an i586 ISA target (--march=i586) or ISA optimization (--mopt=i586) a _de-optimization_ for i686 ISA compatible processors. And that include's Intel's own Pentium Pro/II, III/M, 4, etc...

Just because it's higher doesn't necessarily mean better. Heck, Intel is going back to the P3 core because the P4 core isn't scaling, and it was a really quick hack that has poor ALU and FPU performance MHz for MHz compared to the PPro-P3 design.

-- Bryan J. Smith mailto:b.j.smith@ieee.org