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fpu/softfloat: Refactor floatx80 format NaN classification to share code

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The floatx80_is_[quiet|signaling]_nan functions contain duplicated
logic that should be shared.
This commit introduces floatx80_nan_is_snan helper function that
determine if a NaN is signaling and change the return type of
floatx80_is_[signaling|quiet]_nan to bool.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Max Chou <max.chou@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Chao Liu <chao.liu.zevorn@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20260204051756.667397-4-max.chou@sifive.com>
This commit is contained in:
Max Chou
2026-02-04 13:17:39 +08:00
committed by Richard Henderson
parent 5146b68791
commit dddee8e1ba
2 changed files with 21 additions and 36 deletions
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53
fpu/softfloat-specialize.c.inc
View File

@@ -357,53 +357,38 @@ bool float64_is_signaling_nan(float64 a_, float_status *status)
}
/*----------------------------------------------------------------------------
| Returns 1 if the extended double-precision floating-point value `a' is a
| quiet NaN; otherwise returns 0. This slightly differs from the same
| function for other types as floatx80 has an explicit bit.
| Determine if a floatx80 NaN is signaling NaN.
| The MSB of frac differs from the same function for other types as floatx80
| has an explicit bit.
*----------------------------------------------------------------------------*/
int floatx80_is_quiet_nan(floatx80 a, float_status *status)
static bool floatx80_nan_is_snan(floatx80 a, float_status *status)
{
if (no_signaling_nans(status)) {
return floatx80_is_any_nan(a);
} else {
if (snan_bit_is_one(status)) {
uint64_t aLow;
aLow = a.low & ~0x4000000000000000ULL;
return ((a.high & 0x7FFF) == 0x7FFF)
&& (aLow << 1)
&& (a.low == aLow);
} else {
return ((a.high & 0x7FFF) == 0x7FFF)
&& (UINT64_C(0x8000000000000000) <= ((uint64_t)(a.low << 1)));
}
return false;
}
bool frac_msb_is_one = (a.low >> 62) & 1;
return frac_msb_is_one == snan_bit_is_one(status);
}
/*----------------------------------------------------------------------------
| Returns 1 if the extended double-precision floating-point value `a' is a
| signaling NaN; otherwise returns 0. This slightly differs from the same
| function for other types as floatx80 has an explicit bit.
| quiet NaN; otherwise returns 0.
*----------------------------------------------------------------------------*/
int floatx80_is_signaling_nan(floatx80 a, float_status *status)
bool floatx80_is_quiet_nan(floatx80 a, float_status *status)
{
if (no_signaling_nans(status)) {
return 0;
} else {
if (snan_bit_is_one(status)) {
return ((a.high & 0x7FFF) == 0x7FFF)
&& ((a.low << 1) >= 0x8000000000000000ULL);
} else {
uint64_t aLow;
return floatx80_is_any_nan(a) && !floatx80_nan_is_snan(a, status);
}
aLow = a.low & ~UINT64_C(0x4000000000000000);
return ((a.high & 0x7FFF) == 0x7FFF)
&& (uint64_t)(aLow << 1)
&& (a.low == aLow);
}
}
/*----------------------------------------------------------------------------
| Returns 1 if the extended double-precision floating-point value `a' is a
| signaling NaN; otherwise returns 0.
*----------------------------------------------------------------------------*/
bool floatx80_is_signaling_nan(floatx80 a, float_status *status)
{
return floatx80_is_any_nan(a) && floatx80_nan_is_snan(a, status);
}
/*----------------------------------------------------------------------------

4
include/fpu/softfloat.h
View File

@@ -978,8 +978,8 @@ floatx80 floatx80_rem(floatx80, floatx80, float_status *status);
floatx80 floatx80_sqrt(floatx80, float_status *status);
FloatRelation floatx80_compare(floatx80, floatx80, float_status *status);
FloatRelation floatx80_compare_quiet(floatx80, floatx80, float_status *status);
int floatx80_is_quiet_nan(floatx80, float_status *status);
int floatx80_is_signaling_nan(floatx80, float_status *status);
bool floatx80_is_quiet_nan(floatx80, float_status *status);
bool floatx80_is_signaling_nan(floatx80, float_status *status);
floatx80 floatx80_silence_nan(floatx80, float_status *status);
floatx80 floatx80_scalbn(floatx80, int, float_status *status);