fpu/softfloat: Refactor floatx80 format NaN classification to share code
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>
Max Chou committed
Feb 4, 2026 at 13:17 UTC
dddee8e1ba3e53e8a8e0718943e5e585c731804e
2 files changed
+22
-37
fpu/softfloat-specialize.c.inc
+20
-35
@@ -357,53 +357,38 @@ bool float64_is_signaling_nan(float64 a_, float_status *status)
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}
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/*----------------------------------------------------------------------------
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-| Returns 1 if the extended double-precision floating-point value `a' is a
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-| quiet NaN; otherwise returns 0. This slightly differs from the same
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-| function for other types as floatx80 has an explicit bit.
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+| Determine if a floatx80 NaN is signaling NaN.
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+| The MSB of frac differs from the same function for other types as floatx80
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+| has an explicit bit.
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*----------------------------------------------------------------------------*/
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-int floatx80_is_quiet_nan(floatx80 a, float_status *status)
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+static bool floatx80_nan_is_snan(floatx80 a, float_status *status)
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{
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if (no_signaling_nans(status)) {
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- return floatx80_is_any_nan(a);
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- } else {
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- if (snan_bit_is_one(status)) {
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- uint64_t aLow;
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-
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- aLow = a.low & ~0x4000000000000000ULL;
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- return ((a.high & 0x7FFF) == 0x7FFF)
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- && (aLow << 1)
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- && (a.low == aLow);
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- } else {
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- return ((a.high & 0x7FFF) == 0x7FFF)
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- && (UINT64_C(0x8000000000000000) <= ((uint64_t)(a.low << 1)));
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- }
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+ return false;
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}
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+ bool frac_msb_is_one = (a.low >> 62) & 1;
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+ return frac_msb_is_one == snan_bit_is_one(status);
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}
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/*----------------------------------------------------------------------------
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| Returns 1 if the extended double-precision floating-point value `a' is a
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-| signaling NaN; otherwise returns 0. This slightly differs from the same
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-| function for other types as floatx80 has an explicit bit.
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+| quiet NaN; otherwise returns 0.
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*----------------------------------------------------------------------------*/
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-int floatx80_is_signaling_nan(floatx80 a, float_status *status)
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+bool floatx80_is_quiet_nan(floatx80 a, float_status *status)
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{
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- if (no_signaling_nans(status)) {
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- return 0;
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- } else {
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- if (snan_bit_is_one(status)) {
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- return ((a.high & 0x7FFF) == 0x7FFF)
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- && ((a.low << 1) >= 0x8000000000000000ULL);
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- } else {
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- uint64_t aLow;
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-
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- aLow = a.low & ~UINT64_C(0x4000000000000000);
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- return ((a.high & 0x7FFF) == 0x7FFF)
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- && (uint64_t)(aLow << 1)
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- && (a.low == aLow);
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- }
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- }
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+ return floatx80_is_any_nan(a) && !floatx80_nan_is_snan(a, status);
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+}
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+
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+/*----------------------------------------------------------------------------
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+| Returns 1 if the extended double-precision floating-point value `a' is a
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+| signaling NaN; otherwise returns 0.
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+*----------------------------------------------------------------------------*/
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+
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+bool floatx80_is_signaling_nan(floatx80 a, float_status *status)
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+{
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+ return floatx80_is_any_nan(a) && floatx80_nan_is_snan(a, status);
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}
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/*----------------------------------------------------------------------------
include/fpu/softfloat.h
+2
-2
@@ -978,8 +978,8 @@ floatx80 floatx80_rem(floatx80, floatx80, float_status *status);
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floatx80 floatx80_sqrt(floatx80, float_status *status);
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FloatRelation floatx80_compare(floatx80, floatx80, float_status *status);
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FloatRelation floatx80_compare_quiet(floatx80, floatx80, float_status *status);
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-int floatx80_is_quiet_nan(floatx80, float_status *status);
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-int floatx80_is_signaling_nan(floatx80, float_status *status);
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+bool floatx80_is_quiet_nan(floatx80, float_status *status);
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+bool floatx80_is_signaling_nan(floatx80, float_status *status);
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floatx80 floatx80_silence_nan(floatx80, float_status *status);
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floatx80 floatx80_scalbn(floatx80, int, float_status *status);
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