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A comment on Optimizations Enabled by -ffast-Math. Parent comment

Re:Optimizations Enabled by -ffast-Math by gpderetta on Wednesday October 20, 2021 @04:52AM (#28928351)
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.

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Re:Optimizations Enabled by -ffast-Math by hurrrrrrrr on Wednesday October 20, 2021 @08:24AM (#28929806)
>Certainly do not use finite-math-only when dealing with external data.

so... never?

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Re:Optimizations Enabled by -ffast-Math by gpderetta on Wednesday October 20, 2021 @09:38AM (#28930522)
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.
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