On: Optimizations Enabled by -ffast-Math

[gpderetta]

I think the documentation is fairly clear:

"Allow optimizations for floating-point arithmetic that assume that arguments and results are not NaNs or +-Infs."

The obvious implication is that is that arguments and results are always finite and as a programmer you are responsible of guaranteeing the correct preconditions.

Certainly do not use finite-math-only when dealing with external data.

[hurrrrrrrr → gpderetta]

>Certainly do not use finite-math-only when dealing with external data.

so... never?

[gpderetta → hurrrrrrrr]

let me rephrase: data which you cannot guarantee meet the preconditions. Either the input is known good data or you sanitize it through some code path not compiled with fast-math.