Comment by ksherlock

There was at least one reason...

    long double x87me(long double a, long double b) {
        return a+b;
    }

    pushq %rbp
    movq %rsp, %rbp
    fldt 32(%rbp)
    fldt 16(%rbp)
    faddp %st(1)
    popq %rbp
    retq