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Re: Comparison of GCC-4.9 and LLVM-3.4 performance on SPECInt2000 for x86-64 and ARM


On 2014-06-24, 10:57 AM, Ramana Radhakrishnan wrote:

The ball-park number you have probably won't change much.


I don't think Neon can improve score for SPECInt2000 significantly but
may be I am wrong.

It won't probably improve the overall score by a large amount but some
individual benchmarks will get some help.

Did you add any other architecture specific options to your SPEC2k
runs ?


No.  The only options I used are -Ofast.

Could you recommend me what best options you think I should use for this
processor.


I would personally use --with-cpu=cortex-a15 --with-fpu=neon-vfpv4
--with-float=hard on this processor as that maps with the processor
available on that particular piece of Silicon.


I've tried this options too. As I guessed it resulted in GCC improvement of eon only by 6% which improved overall score by less 0.5%. No change for LLVM though. Eon is more fp benchmark with my point of view and it should be in SPECFP but it is a different story.

I've tried GCC SPECFP2000 also with and without this options and it gave about 12% improvement (1006 vs 988). That is a *huge* improvement. I guess using NEON for ARM is really important for fp benchmarks.


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