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authorRichard Henderson <richard.henderson@linaro.org>2019-02-15 09:02:25 -0800
committerAlex Bennée <alex.bennee@linaro.org>2019-02-26 14:08:03 +0000
commit5d64abb32ffe558e616545819f3e53dd66335994 (patch)
treeca60e7613392eea5f37eaa64be370932476779d2 /fpu
parentdc3f8a9dcfc701c7d528a88e8fc85e727ae5551b (diff)
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softfloat: Support float_round_to_odd more places
Previously this was only supported for roundAndPackFloat64. New support in round_canonical, round_to_int, float128_round_to_int, roundAndPackFloat32, roundAndPackInt32, roundAndPackInt64, roundAndPackUint64. 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.henderson@linaro.org> Message-Id: <20190215170225.15537-1-richard.henderson@linaro.org> Tested-by: David Hildenbrand <david@redhat.com> [AJB: add missing break] Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Diffstat (limited to 'fpu')
-rw-r--r--fpu/softfloat.c65
1 files changed, 60 insertions, 5 deletions
diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index c69cd6b..4610738 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 : round_mask;
+ 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 : round_mask;
+ 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 : rnd_mask;
+ 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 +3551,9 @@ 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;
+ break;
default:
abort();
break;
@@ -3536,8 +3564,10 @@ 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 +3585,13 @@ 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) {
@@ -6987,6 +7024,15 @@ float128 float128_round_to_int(float128 a, float_status *status)
add128(z.high, z.low, 0, roundBitsMask, &z.high, &z.low);
}
break;
+ case float_round_to_odd:
+ /*
+ * Note that if lastBitMask == 0, the last bit is the lsb
+ * of high, and roundBitsMask == -1.
+ */
+ if ((lastBitMask ? z.low & lastBitMask : z.high & 1) == 0) {
+ add128(z.high, z.low, 0, roundBitsMask, &z.high, &z.low);
+ }
+ break;
default:
abort();
}
@@ -6998,7 +7044,7 @@ float128 float128_round_to_int(float128 a, float_status *status)
status->float_exception_flags |= float_flag_inexact;
aSign = extractFloat128Sign( a );
switch (status->float_rounding_mode) {
- case float_round_nearest_even:
+ case float_round_nearest_even:
if ( ( aExp == 0x3FFE )
&& ( extractFloat128Frac0( a )
| extractFloat128Frac1( a ) )
@@ -7011,14 +7057,17 @@ float128 float128_round_to_int(float128 a, float_status *status)
return packFloat128(aSign, 0x3FFF, 0, 0);
}
break;
- case float_round_down:
+ case float_round_down:
return
aSign ? packFloat128( 1, 0x3FFF, 0, 0 )
: packFloat128( 0, 0, 0, 0 );
- case float_round_up:
+ case float_round_up:
return
aSign ? packFloat128( 1, 0, 0, 0 )
: packFloat128( 0, 0x3FFF, 0, 0 );
+
+ case float_round_to_odd:
+ return packFloat128(aSign, 0x3FFF, 0, 0);
}
return packFloat128( aSign, 0, 0, 0 );
}
@@ -7051,6 +7100,12 @@ float128 float128_round_to_int(float128 a, float_status *status)
z.high += roundBitsMask;
}
break;
+ case float_round_to_odd:
+ if ((z.high & lastBitMask) == 0) {
+ z.high |= (a.low != 0);
+ z.high += roundBitsMask;
+ }
+ break;
default:
abort();
}