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Re: What is acceptable for -ffast-math? (Was: associative law incombine)



On Wed, 1 Aug 2001 dewar@gnat.com wrote:
>
> a/2.0/2.0 will never yield zero if a is non-zero
> a/4.0 may indeed yield zero if a is the smallest number

Didn't you already agree that FTZ was acceptable even for a default mode,
much less -ffast-math?

The above rules, btw, only apply for exact IEEE math, and on a number of
machines you _will_ see zero for the first one.

So I don't think your example is a valid argument for not using the
optimization - even without -ffast-math.

			Linus


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