On 05/04/2015 08:36 PM, Levent Erkok wrote:

In particular, the compiler should be free to substitute "a*b+c" with "mulAccum a b c".

But isn't it unacceptable in some cases? For instance, in this case (taken from Wikipedia):

If $x 2 - y 2$ is evaluated as $((x \times x) - y \times y)$ using fused multiply–add, then the result may be negative even when $x = y$ due to the first multiplication discarding low significance bits. This could then lead to an error if, for instance, the square root of the result is then evaluated.