The floating-point status word in a multithreaded environment
Applicable to variants of the software floating-point libraries that require a status word, the floating-point status word is safe to use in a multithreaded environment, even with software floating-point.
A status word for each thread is stored in its own
NoteIn a hardware floating-point environment, the floating-point status word is stored in a Vector Floating-Point (VFP) register. In this case, your thread-switching mechanism must keep a separate copy of this register for each thread.
In ARM Compiler 6 floating-point variants are selected
by default. The armclang command-line option
-ffast-math selects the other variants.