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Re: Change x86 default arch for 4.5?
On Sun, 21 Feb 2010, Richard Guenther wrote:
> We could very well enable -mfpmath=sse as a side-effect of -ffast-math though.
Yes, or sse+387 if that helps. As documented:
@option{-fexcess-precision=standard} is not implemented for languages
other than C, and has no effect if
@option{-funsafe-math-optimizations} or @option{-ffast-math} is
specified. On the x86, it also has no effect if @option{-mfpmath=sse}
or @option{-mfpmath=sse+387} is specified; in the former case, IEEE
semantics apply without excess precision, and in the latter, rounding
is unpredictable.
-funsafe-math-optimizations is expected to have sufficient effects on
floating-point results that they can no longer be said to follow a
particular API as regards excess precision, and so whichever API is
fastest can be used.
--
Joseph S. Myers
joseph@codesourcery.com