Using IEEE 754 algorithm i assume, that it can be implemented in a branchless way.
But how does CPU determine special cases (Reserved Exponent values):
Without any tricks which i don't know / understand it should be expensive.
It was too big for comment, so editing source question:
I'm currently reading ARM spec/documentation https://developer.arm.com/documentation/ddi0403/d/Application-Level-Architecture/Application-Level-Programmers--Model/The-optional-Floating-point-extension/Floating-point-data-types-and-arithmetic?lang=en#BEIBFIBJ and especially interesting part is
FPUnpack() pseudocode. If i understand correctly, CPU doesn't have intrinsics / instructions for special cases, but the compiler, that produce machine code should consider to validate result from registers (FVP for old ones and NEON for new). The example i found from ARM team https://github.com/ARM-software/ComputeLibrary/blob/8f587de9214dbc3aee4ff4eeb2ede66747769b19/include/CL/cl_half.h#L135. Am i right ?
Nope, i'm not right, according to this answer https://stackoverflow.com/questions/61646510/how-does-the-cpu-cast-a-floating-point-x87-i-think-value.
But it's still the question how does CPU registers handle special cases...