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Politics : Formerly About Advanced Micro Devices -- Ignore unavailable to you. Want to Upgrade?

To: Haim Barad who wrote (74527)10/7/1999 2:07:00 PM
From: Process Boy  Respond to of 1572918
 
Haim - <I'll give you an example. The Direct3D API (starting with DX6.1) has an optimized pipeline for PIII. It was almost completely written in C++ and does take advantage of SIMD. The 3D Winbench scores are based upon Direct3D performance. So the answer to your question is yes. (keep in mind that there also is an optimized AMD path written with 3DNOW instructions... although they had to do it in assembly)

HOWEVER!!! The C++ compiler DOES NOT AUTOMATICALLY use SIMD without the user declaring SIMD data structures (e.g. 4-wide Single Precision FP). Since the SPEC benchmark code (both INT and FP) can't be changed, then the "optimized" scores CAN'T BE USING SIMD.>

Thank you for indulging me! Great concise example!!

PB




To: Haim Barad who wrote (74527)10/7/1999 2:08:00 PM
From: Saturn V  Read Replies (1) | Respond to of 1572918
 
Ref-<The C++ compiler DOES NOT AUTOMATICALLY use SIMD without the user declaring SIMD data structures (e.g. 4-wide Single Precision FP). Since the SPEC benchmark code (both INT and FP) can't be changed, then the "optimized" scores CAN'T BE USING SIMD.>

Can you comment on the following:
Does the C++ compiler automatically generate the SSE code,ie automatic prefetch of data ? Can this be applied to the SPEC benchmarks ?

Are there any plans to upgrade the compiler so that SIMD instructions gan be generated automatically (without any extra declarations) ?

Thanks

Saturn 5



To: Haim Barad who wrote (74527)10/7/1999 2:34:00 PM
From: Elmer  Read Replies (1) | Respond to of 1572918
 
Re: "HOWEVER!!! The C++ compiler DOES NOT AUTOMATICALLY use SIMD without the user declaring SIMD data structures (e.g. 4-wide Single Precision FP). Since the SPEC benchmark code (both INT and FP) can't be changed, then the "optimized" scores CAN'T BE USING SIMD."

So are you saying that the SPEC scores reported yesterday did not use SIMD instructions and still beat the K7 by a wide margin in FP, assuming those rumored scores are correct?

EP


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