Do all programming languages adhere to the IEEE 754-2008 standard?
For example, C and C++ don’t adhere to it. They don’t define the details of floating point arithmetic. An implementation may adhere to that standard, and there is a standard way to inform the user about it. 

I used one compiler with ieee compliant 32 and 64 bit floating point, and totally non-compliant 128 bit fp with roughly 105 bit mantissa.