fpu/softfloat: Canonicalize NaN fraction

Shift the NaN fraction to a canonical position, much like we
do for the fraction of normal numbers.  This will facilitate
manipulation of NaNs within the shared code paths.

Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2018-05-10 12:14:21 -07:00
parent 0664335a6e
commit 94933df0e5

View File

@ -330,10 +330,11 @@ static FloatParts canonicalize(FloatParts part, const FloatFmt *parm,
if (part.frac == 0) {
part.cls = float_class_inf;
} else {
part.frac <<= parm->frac_shift;
#ifdef NO_SIGNALING_NANS
part.cls = float_class_qnan;
#else
int64_t msb = part.frac << (parm->frac_shift + 2);
int64_t msb = part.frac << 2;
if ((msb < 0) == status->snan_bit_is_one) {
part.cls = float_class_snan;
} else {
@ -480,6 +481,7 @@ static FloatParts round_canonical(FloatParts p, float_status *s,
case float_class_qnan:
case float_class_snan:
exp = exp_max;
frac >>= parm->frac_shift;
break;
default:
@ -503,6 +505,7 @@ static float16 float16_round_pack_canonical(FloatParts p, float_status *s)
case float_class_dnan:
return float16_default_nan(s);
case float_class_msnan:
p.frac >>= float16_params.frac_shift;
return float16_maybe_silence_nan(float16_pack_raw(p), s);
default:
p = round_canonical(p, s, &float16_params);
@ -521,6 +524,7 @@ static float32 float32_round_pack_canonical(FloatParts p, float_status *s)
case float_class_dnan:
return float32_default_nan(s);
case float_class_msnan:
p.frac >>= float32_params.frac_shift;
return float32_maybe_silence_nan(float32_pack_raw(p), s);
default:
p = round_canonical(p, s, &float32_params);
@ -539,6 +543,7 @@ static float64 float64_round_pack_canonical(FloatParts p, float_status *s)
case float_class_dnan:
return float64_default_nan(s);
case float_class_msnan:
p.frac >>= float64_params.frac_shift;
return float64_maybe_silence_nan(float64_pack_raw(p), s);
default:
p = round_canonical(p, s, &float64_params);