From f8ba1b5654d876c8db4c9a020e6fa976d434f988 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Tue, 10 Jun 2014 12:07:15 +0000 Subject: Fix log2 (1) in round-downward mode (bug 17042). As with other issues of this kind, bug 17042 is log2 (1) wrongly returning -0 instead of +0 in round-downward mode because of implementations effectively in terms of log1p (x - 1). This patch fixes the issue in the same way used for log and log10. Tested x86_64 and x86 and ulps updated accordingly. Also tested for mips64 to confirm a fix was needed for ldbl-128 and to validate that fix (also applied to ldbl-128ibm since that version of log2l is essentially the same as the ldbl-128 one). [BZ #17042] * sysdeps/i386/fpu/e_log2.S (__ieee754_log2): Take absolete value when x - 1 is zero. * sysdeps/i386/fpu/e_log2f.S (__ieee754_log2f): Likewise. * sysdeps/i386/fpu/e_log2l.S (__ieee754_log2l): Likewise. * sysdeps/ieee754/ldbl-128/e_log2l.c (__ieee754_log2l): Return 0.0L for an argument of 1.0L. * sysdeps/ieee754/ldbl-128ibm/e_log2l.c (__ieee754_log2l): Likewise. * sysdeps/x86_64/fpu/e_log2l.S (__ieee754_log2l): Take absolute value when x - 1 is zero. * math/libm-test.inc (log2_test): Use ALL_RM_TEST. * sysdeps/i386/fpu/libm-test-ulps: Update. * sysdeps/x86_64/fpu/libm-test-ulps: Likewise. --- ChangeLog | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'ChangeLog') diff --git a/ChangeLog b/ChangeLog index 0ace298..9055159 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,20 @@ +2014-06-10 Joseph Myers + + [BZ #17042] + * sysdeps/i386/fpu/e_log2.S (__ieee754_log2): Take absolete value + when x - 1 is zero. + * sysdeps/i386/fpu/e_log2f.S (__ieee754_log2f): Likewise. + * sysdeps/i386/fpu/e_log2l.S (__ieee754_log2l): Likewise. + * sysdeps/ieee754/ldbl-128/e_log2l.c (__ieee754_log2l): Return + 0.0L for an argument of 1.0L. + * sysdeps/ieee754/ldbl-128ibm/e_log2l.c (__ieee754_log2l): + Likewise. + * sysdeps/x86_64/fpu/e_log2l.S (__ieee754_log2l): Take absolute + value when x - 1 is zero. + * math/libm-test.inc (log2_test): Use ALL_RM_TEST. + * sysdeps/i386/fpu/libm-test-ulps: Update. + * sysdeps/x86_64/fpu/libm-test-ulps: Likewise. + 2014-06-09 Bernard Ogden [BZ #15119] -- cgit v1.1