Fix ldbl-128ibm ilogbl near powers of 2 (bug 18029).
The ldbl-128ibm implementation of ilogbl produces incorrect results when the high part of the argument is a power of 2 and the low part a nonzero number with the opposite sign (and so the returned exponent should be 1 less than that of the high part). For example, ilogbl (0x1.ffffffffffffffp1L) returns 2 but should return 1. (This is similar to (fixed) bug 16740 for frexpl, and bug 18030 for logbl.) This patch adds checks for that case. Tested for powerpc. [BZ #18029] * sysdeps/ieee754/ldbl-128ibm/e_ilogbl.c (__ieee754_ilogbl): Adjust exponent of power of 2 down when low part has opposite sign. * math/libm-test.inc (ilogb_test_data): Add more tests.
This commit is contained in:
parent
23d43090e0
commit
524ae9ea2e
|
@ -1,3 +1,11 @@
|
|||
2015-02-26 Joseph Myers <joseph@codesourcery.com>
|
||||
|
||||
[BZ #18029]
|
||||
* sysdeps/ieee754/ldbl-128ibm/e_ilogbl.c (__ieee754_ilogbl):
|
||||
Adjust exponent of power of 2 down when low part has opposite
|
||||
sign.
|
||||
* math/libm-test.inc (ilogb_test_data): Add more tests.
|
||||
|
||||
2015-02-26 Alexandre Oliva <aoliva@redhat.com>
|
||||
|
||||
[BZ #15969]
|
||||
|
|
2
NEWS
2
NEWS
|
@ -12,7 +12,7 @@ Version 2.22
|
|||
4719, 14841, 13064, 14094, 15319, 15467, 15790, 15969, 16560, 16783,
|
||||
17269, 17523, 17569, 17588, 17792, 17836, 17912, 17916, 17932, 17944,
|
||||
17949, 17964, 17965, 17967, 17969, 17978, 17987, 17991, 17996, 17998,
|
||||
17999, 18019, 18020.
|
||||
17999, 18019, 18020, 18029.
|
||||
|
||||
* Character encoding and ctype tables were updated to Unicode 7.0.0, using
|
||||
new generator scripts contributed by Pravin Satpute and Mike FABIAN (Red
|
||||
|
|
|
@ -7219,6 +7219,11 @@ static const struct test_f_i_data ilogb_test_data[] =
|
|||
TEST_f_i (ilogb, 1024, 10, NO_INEXACT_EXCEPTION),
|
||||
TEST_f_i (ilogb, -2000, 10, NO_INEXACT_EXCEPTION),
|
||||
|
||||
#if defined TEST_LDOUBLE && LDBL_MANT_DIG >= 57
|
||||
TEST_f_i (ilogb, 0x1.ffffffffffffffp1L, 1, NO_INEXACT_EXCEPTION),
|
||||
TEST_f_i (ilogb, -0x1.ffffffffffffffp1L, 1, NO_INEXACT_EXCEPTION),
|
||||
#endif
|
||||
|
||||
/* ilogb (0.0) == FP_ILOGB0 plus invalid exception */
|
||||
TEST_f_i (ilogb, 0.0, FP_ILOGB0, NO_INEXACT_EXCEPTION|INVALID_EXCEPTION|ERRNO_EDOM),
|
||||
/* ilogb (qNaN) == FP_ILOGBNAN plus invalid exception */
|
||||
|
|
|
@ -31,12 +31,13 @@ static char rcsid[] = "$NetBSD: $";
|
|||
|
||||
int __ieee754_ilogbl(long double x)
|
||||
{
|
||||
int64_t hx;
|
||||
int64_t hx, hxs;
|
||||
int ix;
|
||||
double xhi;
|
||||
double xhi, xlo;
|
||||
|
||||
xhi = ldbl_high (x);
|
||||
ldbl_unpack (x, &xhi, &xlo);
|
||||
EXTRACT_WORDS64 (hx, xhi);
|
||||
hxs = hx;
|
||||
hx &= 0x7fffffffffffffffLL;
|
||||
if(hx <= 0x0010000000000000LL) {
|
||||
if(hx==0)
|
||||
|
@ -45,7 +46,21 @@ int __ieee754_ilogbl(long double x)
|
|||
for (ix = -1022, hx<<=11; hx>0; hx<<=1) ix -=1;
|
||||
return ix;
|
||||
}
|
||||
else if (hx<0x7ff0000000000000LL) return (hx>>52)-0x3ff;
|
||||
else if (hx < 0x7ff0000000000000LL)
|
||||
{
|
||||
int hexp = (hx >> 52) - 0x3ff;
|
||||
/* If the high part is a power of 2, and the low part is
|
||||
nonzero with the opposite sign, the low part affects
|
||||
the exponent. */
|
||||
if ((hx & 0x000fffffffffffffLL) == 0)
|
||||
{
|
||||
int64_t lx;
|
||||
EXTRACT_WORDS64 (lx, xlo);
|
||||
if ((hxs ^ lx) < 0 && (lx & 0x7fffffffffffffffLL) != 0)
|
||||
hexp--;
|
||||
}
|
||||
return hexp;
|
||||
}
|
||||
else if (FP_ILOGBNAN != INT_MAX) {
|
||||
/* ISO C99 requires ilogbl(+-Inf) == INT_MAX. */
|
||||
if (hx==0x7ff0000000000000LL)
|
||||
|
|
Loading…
Reference in New Issue