Fix some more dbl-64/s_fma.c issue
This commit is contained in:
Jakub Jelinek
Ulrich Drepper
parent
14d43591fa
commit
f3f7372de1
@ -1,3 +1,10 @@
|
||||
2010-10-14 Jakub Jelinek <jakub@redhat.com>
|
||||
|
||||
[BZ #3268]
|
||||
* math/libm-test.inc (fma_test): Add some more tests.
|
||||
* sysdeps/ieee754/dbl-64/s_fma.c (__fma): Handle underflows
|
||||
correctly.
|
||||
|
||||
2010-10-15 Andreas Schwab <schwab@redhat.com>
|
||||
|
||||
* scripts/data/localplt-s390-linux-gnu.data: New file.
|
||||
|
||||
@ -2808,6 +2808,16 @@ fma_test (void)
|
||||
TEST_fff_f (fma, 0x1.fffffffffffffp+1023, 0x1.001p+0, -0x1.fffffffffffffp+1023, 0x1.fffffffffffffp+1011);
|
||||
TEST_fff_f (fma, -0x1.fffffffffffffp+1023, 0x1.fffffffffffffp+0, 0x1.fffffffffffffp+1023, -0x1.ffffffffffffdp+1023);
|
||||
TEST_fff_f (fma, 0x1.fffffffffffffp+1023, 2.0, -0x1.fffffffffffffp+1023, 0x1.fffffffffffffp+1023);
|
||||
TEST_fff_f (fma, 0x1.6a09e667f3bccp-538, 0x1.6a09e667f3bccp-538, 0.0, 0.0);
|
||||
TEST_fff_f (fma, 0x1.deadbeef2feedp-495, 0x1.deadbeef2feedp-495, -0x1.bf86a5786a574p-989, 0x0.0000042625a1fp-1022);
|
||||
TEST_fff_f (fma, 0x1.deadbeef2feedp-503, 0x1.deadbeef2feedp-503, -0x1.bf86a5786a574p-1005, 0x0.0000000004262p-1022);
|
||||
TEST_fff_f (fma, 0x1p-537, 0x1p-538, 0x1p-1074, 0x0.0000000000002p-1022);
|
||||
TEST_fff_f (fma, 0x1.7fffff8p-968, 0x1p-106, 0x0.000001p-1022, 0x0.0000010000001p-1022);
|
||||
TEST_fff_f (fma, 0x1.4000004p-967, 0x1p-106, 0x0.000001p-1022, 0x0.0000010000003p-1022);
|
||||
TEST_fff_f (fma, 0x1.4p-967, -0x1p-106, -0x0.000001p-1022, -0x0.0000010000002p-1022);
|
||||
TEST_fff_f (fma, -0x1.19cab66d73e17p-959, 0x1.c7108a8c5ff51p-107, -0x0.80b0ad65d9b64p-1022, -0x0.80b0ad65d9d59p-1022);
|
||||
TEST_fff_f (fma, -0x1.d2eaed6e8e9d3p-979, -0x1.4e066c62ac9ddp-63, -0x0.9245e6b003454p-1022, -0x0.9245c09c5fb5dp-1022);
|
||||
TEST_fff_f (fma, 0x1.153d650bb9f06p-907, 0x1.2d01230d48407p-125, -0x0.b278d5acfc3cp-1022, -0x0.b22757123bbe9p-1022);
|
||||
#endif
|
||||
|
||||
END (fma);
|
||||
|
||||
@ -39,15 +39,20 @@ __fma (double x, double y, double z)
|
||||
>= 0x7ff + IEEE754_DOUBLE_BIAS - DBL_MANT_DIG, 0)
|
||||
|| __builtin_expect (u.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
|
||||
|| __builtin_expect (v.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
|
||||
|| __builtin_expect (w.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0))
|
||||
|| __builtin_expect (w.ieee.exponent >= 0x7ff - DBL_MANT_DIG, 0)
|
||||
|| __builtin_expect (u.ieee.exponent + v.ieee.exponent
|
||||
<= IEEE754_DOUBLE_BIAS + DBL_MANT_DIG, 0))
|
||||
{
|
||||
/* If x or y or z is Inf/NaN or if fma will certainly overflow,
|
||||
/* If x or y or z is Inf/NaN, or if fma will certainly overflow,
|
||||
or if x * y is less than half of DBL_DENORM_MIN,
|
||||
compute as x * y + z. */
|
||||
if (u.ieee.exponent == 0x7ff
|
||||
|| v.ieee.exponent == 0x7ff
|
||||
|| w.ieee.exponent == 0x7ff
|
||||
|| u.ieee.exponent + v.ieee.exponent
|
||||
> 0x7ff + IEEE754_DOUBLE_BIAS)
|
||||
> 0x7ff + IEEE754_DOUBLE_BIAS
|
||||
|| u.ieee.exponent + v.ieee.exponent
|
||||
< IEEE754_DOUBLE_BIAS - DBL_MANT_DIG - 2)
|
||||
return x * y + z;
|
||||
if (u.ieee.exponent + v.ieee.exponent
|
||||
>= 0x7ff + IEEE754_DOUBLE_BIAS - DBL_MANT_DIG)
|
||||
@ -87,7 +92,7 @@ __fma (double x, double y, double z)
|
||||
else
|
||||
v.d *= 0x1p53;
|
||||
}
|
||||
else
|
||||
else if (v.ieee.exponent >= 0x7ff - DBL_MANT_DIG)
|
||||
{
|
||||
v.ieee.exponent -= DBL_MANT_DIG;
|
||||
if (u.ieee.exponent)
|
||||
@ -95,6 +100,24 @@ __fma (double x, double y, double z)
|
||||
else
|
||||
u.d *= 0x1p53;
|
||||
}
|
||||
else /* if (u.ieee.exponent + v.ieee.exponent
|
||||
<= IEEE754_DOUBLE_BIAS + DBL_MANT_DIG) */
|
||||
{
|
||||
if (u.ieee.exponent > v.ieee.exponent)
|
||||
u.ieee.exponent += 2 * DBL_MANT_DIG;
|
||||
else
|
||||
v.ieee.exponent += 2 * DBL_MANT_DIG;
|
||||
if (w.ieee.exponent <= 4 * DBL_MANT_DIG + 4)
|
||||
{
|
||||
if (w.ieee.exponent)
|
||||
w.ieee.exponent += 2 * DBL_MANT_DIG;
|
||||
else
|
||||
w.d *= 0x1p106;
|
||||
adjust = -1;
|
||||
}
|
||||
/* Otherwise x * y should just affect inexact
|
||||
and nothing else. */
|
||||
}
|
||||
x = u.d;
|
||||
y = v.d;
|
||||
z = w.d;
|
||||
@ -123,18 +146,68 @@ __fma (double x, double y, double z)
|
||||
fesetround (FE_TOWARDZERO);
|
||||
/* Perform m2 + a2 addition with round to odd. */
|
||||
u.d = a2 + m2;
|
||||
if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7ff)
|
||||
u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
|
||||
feupdateenv (&env);
|
||||
|
||||
/* Add that to a1. */
|
||||
a1 = a1 + u.d;
|
||||
|
||||
/* And adjust exponent if needed. */
|
||||
if (__builtin_expect (adjust, 0))
|
||||
a1 *= 0x1p53;
|
||||
|
||||
return a1;
|
||||
if (__builtin_expect (adjust == 0, 1))
|
||||
{
|
||||
if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7ff)
|
||||
u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
|
||||
feupdateenv (&env);
|
||||
/* Result is a1 + u.d. */
|
||||
return a1 + u.d;
|
||||
}
|
||||
else if (__builtin_expect (adjust > 0, 1))
|
||||
{
|
||||
if ((u.ieee.mantissa1 & 1) == 0 && u.ieee.exponent != 0x7ff)
|
||||
u.ieee.mantissa1 |= fetestexcept (FE_INEXACT) != 0;
|
||||
feupdateenv (&env);
|
||||
/* Result is a1 + u.d, scaled up. */
|
||||
return (a1 + u.d) * 0x1p53;
|
||||
}
|
||||
else
|
||||
{
|
||||
v.d = a1 + u.d;
|
||||
int j = fetestexcept (FE_INEXACT) != 0;
|
||||
feupdateenv (&env);
|
||||
/* Ensure the following computations are performed in default rounding
|
||||
mode instead of just reusing the round to zero computation. */
|
||||
asm volatile ("" : "=m" (u) : "m" (u));
|
||||
/* If a1 + u.d is exact, the only rounding happens during
|
||||
scaling down. */
|
||||
if (j == 0)
|
||||
return v.d * 0x1p-106;
|
||||
/* If result rounded to zero is not subnormal, no double
|
||||
rounding will occur. */
|
||||
if (v.ieee.exponent > 106)
|
||||
return (a1 + u.d) * 0x1p-106;
|
||||
/* If v.d * 0x1p-106 with round to zero is a subnormal above
|
||||
or equal to DBL_MIN / 2, then v.d * 0x1p-106 shifts mantissa
|
||||
down just by 1 bit, which means v.ieee.mantissa1 |= j would
|
||||
change the round bit, not sticky or guard bit.
|
||||
v.d * 0x1p-106 never normalizes by shifting up,
|
||||
so round bit plus sticky bit should be already enough
|
||||
for proper rounding. */
|
||||
if (v.ieee.exponent == 106)
|
||||
{
|
||||
/* v.ieee.mantissa1 & 2 is LSB bit of the result before rounding,
|
||||
v.ieee.mantissa1 & 1 is the round bit and j is our sticky
|
||||
bit. In round-to-nearest 001 rounds down like 00,
|
||||
011 rounds up, even though 01 rounds down (thus we need
|
||||
to adjust), 101 rounds down like 10 and 111 rounds up
|
||||
like 11. */
|
||||
if ((v.ieee.mantissa1 & 3) == 1)
|
||||
{
|
||||
v.d *= 0x1p-106;
|
||||
if (v.ieee.negative)
|
||||
return v.d - 0x1p-1074 /* __DBL_DENORM_MIN__ */;
|
||||
else
|
||||
return v.d + 0x1p-1074 /* __DBL_DENORM_MIN__ */;
|
||||
}
|
||||
else
|
||||
return v.d * 0x1p-106;
|
||||
}
|
||||
v.ieee.mantissa1 |= j;
|
||||
return v.d * 0x1p-106;
|
||||
}
|
||||
}
|
||||
#ifndef __fma
|
||||
weak_alias (__fma, fma)
|
||||
|
||||
Loading…
Reference in New Issue
Block a user