On plan9

    Trying compiler constants first...

    f  is 0.12345, rounded to 0.1235, expanded to 0.123450003564357760000000000000
    d  is 0.12345, rounded to 0.1235, expanded to 0.123450000000000000000000000000
    ld is 0.12345, rounded to 0.1235, expanded to 0.123450000000000000000000000000

    Now trying derived values...

    f  is 0.12345, rounded to 0.1235, expanded to 0.123450003564357760000000000000
    d  is 0.12345, rounded to 0.1235, expanded to 0.123450000000000000000000000000
    ld is 0.12345, rounded to 0.1235, expanded to 0.123450000000000000000000000000

So don't blame the architecture