GCC and Floating-Point

[Daniel Berlin]

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.