CODEWITHSUNDEEP
c++gccoptimizationfloating-pointfast-math
Huy Le
Huy Le

Reputation: 1738

C++ gcc does associative-math flag disable float NAN values?

I'm working with statistic functions with a lot of float data. I want it to run faster but Ofast disable NAN (fno-finite-math-only flag), which is not allowed in my case.

In this case, is it safe to turn on only associative-math ? I think this flag allows things like vectorized sum of vector array, even if the array contains NAN.

Upvotes: 0

Views: 209

Answers (1)

Thomas
Thomas

Reputation: 181845

From the docs:

NOTE: re-ordering may change the sign of zero as well as ignore NaNs

So if you want correct handling of NaNs, you should not use -fassociative-math.

Upvotes: 1

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