[9fans] what does #pragma fpround do?

[erik quanstrom]

reading 8c (the only compiler that appears to
implement this pragma), the difference appears
to be in the conversion of (double, float) ->
any type of integer.  however,

        #include <u.h>
        #include <libc.h>

        void
        main(void)
        {
                double d;

                d = 1.99999999999;
        #pragma fpround on
                print("%d\n", (int)d);
        #pragma fpround 0
                print("%d\n", (int)d);
        }

generates the same output and same assembly
for both casts.  can anyone explain what this pragma
is supposed to do?

- erik