With a canonical representation of NaNs, we can silence an SNaN
immediately rather than delay until the final format is known.
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
fpu/softfloat-specialize.h | 23 +++++++++++++++++
fpu/softfloat.c | 51 +++++++++++---------------------------
2 files changed, 38 insertions(+), 36 deletions(-)
diff --git a/fpu/softfloat-specialize.h b/fpu/softfloat-specialize.h
index 2ad524b11e..53a4f45a8c 100644
--- a/fpu/softfloat-specialize.h
+++ b/fpu/softfloat-specialize.h
@@ -138,6 +138,29 @@ static FloatParts parts_default_nan(float_status *status)
};
}
+/*----------------------------------------------------------------------------
+| Returns a quiet NaN from a signalling NaN for the deconstructed
+| floating-point parts.
+*----------------------------------------------------------------------------*/
+
+static FloatParts parts_silence_nan(FloatParts a, float_status *status)
+{
+#ifdef NO_SIGNALING_NANS
+ g_assert_not_reached();
+#elif defined(TARGET_HPPA)
+ a.frac &= ~(1ULL << (DECOMPOSED_BINARY_POINT - 1));
+ a.frac |= 1ULL << (DECOMPOSED_BINARY_POINT - 2);
+#else
+ if (status->snan_bit_is_one) {
+ return parts_default_nan(status);
+ } else {
+ a.frac |= 1ULL << (DECOMPOSED_BINARY_POINT - 1);
+ }
+#endif
+ a.cls = float_class_qnan;
+ return a;
+}
+
/*----------------------------------------------------------------------------
| The pattern for a default generated half-precision NaN.
*----------------------------------------------------------------------------*/
diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 01036b158e..cce94136d4 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -179,7 +179,6 @@ typedef enum __attribute__ ((__packed__)) {
float_class_inf,
float_class_qnan, /* all NaNs from here */
float_class_snan,
- float_class_msnan, /* maybe silenced */
} FloatClass;
/*
@@ -519,13 +518,7 @@ static FloatParts float16_unpack_canonical(float16 f,
float_status *s)
static float16 float16a_round_pack_canonical(const FloatFmt *params,
FloatParts p, float_status *s)
{
- switch (p.cls) {
- case float_class_msnan:
- return float16_maybe_silence_nan(float16_pack_raw(p), s);
- default:
- p = round_canonical(p, s, params);
- return float16_pack_raw(p);
- }
+ return float16_pack_raw(round_canonical(p, s, params));
}
static float16 float16_round_pack_canonical(FloatParts p, float_status *s)
@@ -540,13 +533,7 @@ static FloatParts float32_unpack_canonical(float32 f,
float_status *s)
static float32 float32_round_pack_canonical(FloatParts p, float_status *s)
{
- switch (p.cls) {
- case float_class_msnan:
- return float32_maybe_silence_nan(float32_pack_raw(p), s);
- default:
- p = round_canonical(p, s, &float32_params);
- return float32_pack_raw(p);
- }
+ return float32_pack_raw(round_canonical(p, s, &float32_params));
}
static FloatParts float64_unpack_canonical(float64 f, float_status *s)
@@ -556,13 +543,7 @@ static FloatParts float64_unpack_canonical(float64 f,
float_status *s)
static float64 float64_round_pack_canonical(FloatParts p, float_status *s)
{
- switch (p.cls) {
- case float_class_msnan:
- return float64_maybe_silence_nan(float64_pack_raw(p), s);
- default:
- p = round_canonical(p, s, &float64_params);
- return float64_pack_raw(p);
- }
+ return float64_pack_raw(round_canonical(p, s, &float64_params));
}
/* Simple helpers for checking if what NaN we have */
@@ -570,10 +551,12 @@ static bool is_nan(FloatClass c)
{
return unlikely(c >= float_class_qnan);
}
+
static bool is_snan(FloatClass c)
{
return c == float_class_snan;
}
+
static bool is_qnan(FloatClass c)
{
return c == float_class_qnan;
@@ -584,7 +567,7 @@ static FloatParts return_nan(FloatParts a, float_status *s)
switch (a.cls) {
case float_class_snan:
s->float_exception_flags |= float_flag_invalid;
- a.cls = float_class_msnan;
+ a = parts_silence_nan(a, s);
/* fall through */
case float_class_qnan:
if (s->default_nan_mode) {
@@ -613,7 +596,9 @@ static FloatParts pick_nan(FloatParts a, FloatParts b,
float_status *s)
(a.frac == b.frac && a.sign < b.sign))) {
a = b;
}
- a.cls = float_class_msnan;
+ if (is_snan(a.cls)) {
+ return parts_silence_nan(a, s);
+ }
}
return a;
}
@@ -645,8 +630,9 @@ static FloatParts pick_nan_muladd(FloatParts a, FloatParts
b, FloatParts c,
default:
g_assert_not_reached();
}
-
- a.cls = float_class_msnan;
+ if (is_snan(a.cls)) {
+ return parts_silence_nan(a, s);
+ }
}
return a;
}
@@ -1245,14 +1231,9 @@ static FloatParts float_to_float(FloatParts a,
if (s->default_nan_mode) {
return parts_default_nan(s);
}
-
- /*
- * Reset a.exp to the destination format exp_max as
- * the maybe_silence_nan code assumes it is correct
- * (which it would be for non-conversions).
- */
- a.exp = dstf->exp_max;
- a.cls = float_class_msnan;
+ if (is_snan(a.cls)) {
+ return parts_silence_nan(a, s);
+ }
}
return a;
@@ -1459,7 +1440,6 @@ static int64_t round_to_int_and_pack(FloatParts in, int
rmode,
switch (p.cls) {
case float_class_snan:
case float_class_qnan:
- case float_class_msnan:
s->float_exception_flags = orig_flags | float_flag_invalid;
return max;
case float_class_inf:
@@ -1550,7 +1530,6 @@ static uint64_t round_to_uint_and_pack(FloatParts in, int
rmode, uint64_t max,
switch (p.cls) {
case float_class_snan:
case float_class_qnan:
- case float_class_msnan:
s->float_exception_flags = orig_flags | float_flag_invalid;
return max;
case float_class_inf:
--
2.17.0
