diff options
| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | NEWS | 2 | ||||
| -rw-r--r-- | math/libm-test.inc | 5 | ||||
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/s_logbl.c | 17 |
4 files changed, 27 insertions, 4 deletions
diff --git a/ChangeLog b/ChangeLog index 90c42c85a3..ac6110b965 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,10 @@ +2015-02-26 Joseph Myers <joseph@codesourcery.com> + + [BZ #18030] + * sysdeps/ieee754/ldbl-128ibm/s_logbl.c (__logbl): Adjust exponent + of power of 2 down when low part has opposite sign. + * math/libm-test.inc (logb_test_data): Add more tests. + 2015-02-26 Andreas Schwab <schwab@suse.de> [BZ #18032] diff --git a/NEWS b/NEWS index 77e081464d..f09ffb1ccd 100644 --- a/NEWS +++ b/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, 18029, 18032. + 17999, 18019, 18020, 18029, 18030, 18032. * Character encoding and ctype tables were updated to Unicode 7.0.0, using new generator scripts contributed by Pravin Satpute and Mike FABIAN (Red diff --git a/math/libm-test.inc b/math/libm-test.inc index 6045764fd3..7acd29bc13 100644 --- a/math/libm-test.inc +++ b/math/libm-test.inc @@ -7868,6 +7868,11 @@ static const struct test_f_f_data logb_test_data[] = TEST_f_f (logb, 0x1p-16400L, -16400, NO_INEXACT_EXCEPTION), TEST_f_f (logb, 0x.00000000001p-16382L, -16426, NO_INEXACT_EXCEPTION), #endif + +#if defined TEST_LDOUBLE && LDBL_MANT_DIG >= 57 + TEST_f_f (logb, 0x1.ffffffffffffffp1L, 1, NO_INEXACT_EXCEPTION), + TEST_f_f (logb, -0x1.ffffffffffffffp1L, 1, NO_INEXACT_EXCEPTION), +#endif }; static void diff --git a/sysdeps/ieee754/ldbl-128ibm/s_logbl.c b/sysdeps/ieee754/ldbl-128ibm/s_logbl.c index dbd3478e63..22e5fc24c0 100644 --- a/sysdeps/ieee754/ldbl-128ibm/s_logbl.c +++ b/sysdeps/ieee754/ldbl-128ibm/s_logbl.c @@ -26,11 +26,12 @@ long double __logbl (long double x) { - int64_t hx, rhx; - double xhi; + int64_t hx, hxs, rhx; + double xhi, xlo; - xhi = ldbl_high (x); + ldbl_unpack (x, &xhi, &xlo); EXTRACT_WORDS64 (hx, xhi); + hxs = hx; hx &= 0x7fffffffffffffffLL; /* high |x| */ if (hx == 0) return -1.0 / fabs (x); @@ -42,6 +43,16 @@ __logbl (long double x) though it were normalized. */ rhx -= __builtin_clzll (hx) - 12; } + else if ((hx & 0x000fffffffffffffLL) == 0) + { + /* 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. */ + int64_t lx; + EXTRACT_WORDS64 (lx, xlo); + if ((hxs ^ lx) < 0 && (lx & 0x7fffffffffffffffLL) != 0) + rhx--; + } return (long double) (rhx - 1023); } #ifndef __logbl |