How to determine hardware support for a function (eg fma from math.h C99) using gdb?

Question

gdb

Playing around repeating the standard library for C99, a function is defined in math.h

fma(x,y,z) {
    return (x*y) + z;
}

which has a hardware implementation in some x86 and many arm's. The question arose: I compiled for the target platform with debug symbols, hooked up gdb ... And how to determine whether the hardware support for this function on the target platform is processed at runtime, so as not to explicitly request support through the specifications?