Originally posted by Ensoniq
The point Rower_CPU was making about SSE2 and SPEC was this I believe...
Some people originally complained that SSE2 had not been enabled for the testing...which turned out to be false. But the assertion was that if SSE2 HAD been turned on (which it was) that the SPEC scores would have been higher.
For this to be true, it means that not only would SSE2 need to be enabled in the compiler (which it was) but that SPEC would have to recognize SSE2 in order for the test scores to come out better. Meaning, SPEC has SOME code in it specifically to check for and use SSE2 if it's available. I don't know if that's true, but that's the assertion I believe Rower_CPU made.
SPEC is a set of source code, when an intelligent compiler complies SPEC it has the ability to make use of all features of the CPU that are enabled. SPEC does not need to check for SSE2 at all, the compiler simply has to be setup to make use of it. If such a compiler has the switches thrown at compile time to use SSE2 and the data types and operations done are placeable into the SSE instruction unit SPEC could make use of the hardware. SPEC itself does not need to enable or check anything.
Whether it's true or not, what's perfectly clear is that the SPEC test does NOT have any code in it to detect and use AltiVec if it's available. So even if Apple had used special flags in GCC to enable the use of AltiVec (which they specificially did NOT use, even though they turned on SSE2 for their x86 counterparts), SPEC wouldn't have looked for it.
As above it is a compiler issue, SPEC doesn't have to look for it. My suspicion is that if Apple had a compiler available that supported AltVec they would have runned the SPEC suite with the support enabled and disabled and published the best figures.
So if SPEC is designed to use SSE2 (not certain) but is NOT designed to use AltiVec (an absolute fact) than right out of the gate it shows that SPEC would have an inherent bias BUILT-IN to skew scores more favorably to the x86 processors. How come no one goes out of their way to point out how THAT might be considered cheating at worst, an unfair advantage at best?
Its the compiler and the switches set at compile time. SPEC has nothing to do with it, the better the compiler the more likely it will use as many features as possible of the processor.
So far, the only claims of "cheating" have come when it may have given the Mac an edge. And though there is STILL no shred of evidence of true cheating by Apple (even the admissions on the PC side that Intel, AMD, and ATI do it, so Apple MUST too remains less than credible), it's the only drum for the Wintelers to keep banging...so that is what they have done.
-- Ensoniq
Apple has done a good job with SPEC. It sdoes appear though that some have gotten a little to excited over the SPEC results. We really need to wait until the real machines hit the market and we can run real world tests on them. This will clear up alot of outstanding questions.
thanks
Dave
