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Re: [PATCH] BZ #14649: Add multiarch FMA support to x86-64 libm


On Mon, 1 Oct 2012, H.J. Lu wrote:

> I think some AMD processors support both FMA and FMA4.  But Intel
> processors only support FMA.   My patch follows s_fma.c which prefers
> FMA over FMA4.

The patch doesn't seem to touch sysdeps/x86_64/fpu/dla.h (which deals, for 
FMA4, with cases where various libm code can explicitly use fma operations 
directly) - I'd think you should do something to handle __FMA__ there 
similarly to __FMA4__.  (Although making the generic code use 
__builtin_fma, if __FP_FAST_FMA is defined, would be even better and 
reduce any need for architecture-specific definitions using inline asm.)

-- 
Joseph S. Myers
joseph@codesourcery.com


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