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Re: GCC and Floating-Point



On Thu, 26 May 2005, Vincent Lefevre wrote:

On 2005-05-25 19:27:21 +0200, Allan Sandfeld Jensen wrote: 
Yes. I still don't understand why gcc doesn't do -ffast-math by
default like all other compilers.

No! And I really don't think that other compilers do that.

Have you looked, or are you just guessing?

I know for a fact that XLC does it at -O3+, and unless i'm misremembering, icc does it at -O2+.

Both require flags to turn the behavior *off* at those opt levels.

XLC will give you a warning when it sees itself making an optimization that may affect precision, saying that if you don't want this to happen, to use a flag.

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