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Re: [BENCHMARK] -mfpmath=sse should disable x387 intrinsics


Richard Guenther wrote:

Yes, Roger's patch is a good thing, and should stay in. Previously, you
didn't have any switch available to turn i387 intrinsics off.



Err, but if I want the previous -mfpmath=sse behavior there is now no
way for it.
-mfpmath=sse,387 generates different code than -mfpmath=sse before.


Indeed. -mfpmath=sse,387 enables TARGET_MIX_SSE_I387, and this enables fadd/fsub/fmul/fdiv and fild instructions. These arithmetic instructions have higher latency than their sse equivalents. AFAIK, arithmetic i387 insns and their sse equivalents fight for the same resources in case of pentium4.

Uros.


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