Richard Henderson <richard.hender...@linaro.org> writes:
> Previously this was only supported for roundAndPackFloat64.
> Include support in round_canonical, round_to_int, roundAndPackFloat32,
> roundAndPackInt32, roundAndPackInt64, roundAndPackUint64.
If we extend the fp-test case we can exercise these routines:
./fp-test f16_roundToInt f32_roundToInt f64_roundToInt -r odd
>> Testing f16_roundToInt, rounding odd, exact
Not implemented.
>> Testing f32_roundToInt, rounding odd, exact
Not implemented.
>> Testing f64_roundToInt, rounding odd, exact
Not implemented.
See 4cb780920 for an example...
>
> This does not include any of the floatx80 routines, as we
> do not have users for that rounding mode there.
>
> Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
> ---
>
> David, if you could test this vs your s390 patches, vs real s390
> hardware, that would be lovely.
>
>
> r~
>
> ---
> fpu/softfloat.c | 40 ++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 38 insertions(+), 2 deletions(-)
>
> diff --git a/fpu/softfloat.c b/fpu/softfloat.c
> index 9132d7a0b0..325c6e4e79 100644
> --- a/fpu/softfloat.c
> +++ b/fpu/softfloat.c
> @@ -696,6 +696,7 @@ static FloatParts sf_canonicalize(FloatParts part, const
> FloatFmt *parm,
> static FloatParts round_canonical(FloatParts p, float_status *s,
> const FloatFmt *parm)
> {
> + const uint64_t frac_lsb = parm->frac_lsb;
> const uint64_t frac_lsbm1 = parm->frac_lsbm1;
> const uint64_t round_mask = parm->round_mask;
> const uint64_t roundeven_mask = parm->roundeven_mask;
> @@ -731,6 +732,10 @@ static FloatParts round_canonical(FloatParts p,
> float_status *s,
> inc = p.sign ? round_mask : 0;
> overflow_norm = !p.sign;
> break;
> + case float_round_to_odd:
> + overflow_norm = true;
> + inc = frac & frac_lsb ? 0 : frac_lsbm1;
> + break;
> default:
> g_assert_not_reached();
> }
> @@ -778,9 +783,14 @@ static FloatParts round_canonical(FloatParts p,
> float_status *s,
> shift64RightJamming(frac, 1 - exp, &frac);
> if (frac & round_mask) {
> /* Need to recompute round-to-even. */
> - if (s->float_rounding_mode == float_round_nearest_even) {
> + switch (s->float_rounding_mode) {
> + case float_round_nearest_even:
> inc = ((frac & roundeven_mask) != frac_lsbm1
> ? frac_lsbm1 : 0);
> + break;
> + case float_round_to_odd:
> + inc = frac & frac_lsb ? 0 : frac_lsbm1;
> + break;
> }
> flags |= float_flag_inexact;
> frac += inc;
> @@ -1988,6 +1998,9 @@ static FloatParts round_to_int(FloatParts a, int rmode,
> case float_round_down:
> one = a.sign;
> break;
> + case float_round_to_odd:
> + one = true;
> + break;
> default:
> g_assert_not_reached();
> }
> @@ -2021,6 +2034,9 @@ static FloatParts round_to_int(FloatParts a, int rmode,
> case float_round_down:
> inc = a.sign ? rnd_mask : 0;
> break;
> + case float_round_to_odd:
> + inc = a.frac & frac_lsb ? 0 : frac_lsbm1;
> + break;
> default:
> g_assert_not_reached();
> }
> @@ -3314,6 +3330,9 @@ static int32_t roundAndPackInt32(flag zSign, uint64_t
> absZ, float_status *status
> case float_round_down:
> roundIncrement = zSign ? 0x7f : 0;
> break;
> + case float_round_to_odd:
> + roundIncrement = absZ & 0x80 ? 0 : 0x7f;
> + break;
> default:
> abort();
> }
> @@ -3368,6 +3387,9 @@ static int64_t roundAndPackInt64(flag zSign, uint64_t
> absZ0, uint64_t absZ1,
> case float_round_down:
> increment = zSign && absZ1;
> break;
> + case float_round_to_odd:
> + increment = !(absZ0 & 1) && absZ1;
> + break;
> default:
> abort();
> }
> @@ -3424,6 +3446,9 @@ static int64_t roundAndPackUint64(flag zSign, uint64_t
> absZ0,
> case float_round_down:
> increment = zSign && absZ1;
> break;
> + case float_round_to_odd:
> + increment = !(absZ0 & 1) && absZ1;
> + break;
> default:
> abort();
> }
> @@ -3526,6 +3551,8 @@ static float32 roundAndPackFloat32(flag zSign, int
> zExp, uint32_t zSig,
> case float_round_down:
> roundIncrement = zSign ? 0x7f : 0;
> break;
> + case float_round_to_odd:
> + roundIncrement = zSig & 0x80 ? 0 : 0x7f;
> default:
> abort();
> break;
> @@ -3536,8 +3563,10 @@ static float32 roundAndPackFloat32(flag zSign, int
> zExp, uint32_t zSig,
> || ( ( zExp == 0xFD )
> && ( (int32_t) ( zSig + roundIncrement ) < 0 ) )
> ) {
> + bool overflow_to_inf = roundingMode != float_round_to_odd &&
> + roundIncrement != 0;
> float_raise(float_flag_overflow | float_flag_inexact, status);
> - return packFloat32( zSign, 0xFF, - ( roundIncrement == 0 ));
> + return packFloat32(zSign, 0xFF, -!overflow_to_inf);
> }
> if ( zExp < 0 ) {
> if (status->flush_to_zero) {
> @@ -3555,6 +3584,13 @@ static float32 roundAndPackFloat32(flag zSign, int
> zExp, uint32_t zSig,
> if (isTiny && roundBits) {
> float_raise(float_flag_underflow, status);
> }
> + if (roundingMode == float_round_to_odd) {
> + /*
> + * For round-to-odd case, the roundIncrement depends on
> + * zSig which just changed.
> + */
> + roundIncrement = zSig & 0x80 ? 0 : 0x7f;
> + }
> }
> }
> if (roundBits) {
--
Alex Bennée
