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Re: Patch gcc-4.0 should not apply mathematical associative rules for addition or multiplication


On Oct 7, 2004, at 10:12 PM, Geoff Keating wrote:
On 07/10/2004, at 8:41 PM, Roger Sayle wrote:

Fixing this problem may hurt our SPECfp2000 scores :<

Only if you don't run SPECfp with -ffast-math. (The SPEC rules appear to specifically allow the use of flags like -ffast-math.)

No. The SPEC (2000) rules address the point specifically:


2.2.5 Floating point reordering allowed

Base results may use flags which affect the numerical accuracy or
sensitivity by reordering floating-point operations based on algebraic
identities.


Apple indeed uses -ffast-math for its SPEC results, and I expect everybody
else does too (they should be). So whatever we do about this issue will
not affect SPEC.



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