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authorJoseph Myers <joseph@codesourcery.com>2014-06-10 12:07:15 +0000
committerJoseph Myers <joseph@codesourcery.com>2014-06-10 12:07:15 +0000
commitf8ba1b5654d876c8db4c9a020e6fa976d434f988 (patch)
treef5e34ce57471cbb1c54ec4cd0492b665f94151bb /NEWS
parent2c3520d98d9773d9e092196c3c36150244eed1dd (diff)
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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.
Diffstat (limited to 'NEWS')
-rw-r--r--NEWS2
1 files changed, 1 insertions, 1 deletions
diff --git a/NEWS b/NEWS
index 622cdbf21d..ca3ef633b0 100644
--- a/NEWS
+++ b/NEWS
@@ -19,7 +19,7 @@ Version 2.20
   16791, 16796, 16799, 16800, 16815, 16823, 16824, 16831, 16838, 16849,
   16854, 16876, 16877, 16878, 16882, 16885, 16888, 16890, 16912, 16915,
   16916, 16917, 16922, 16927, 16928, 16932, 16943, 16958, 16965, 16966,
-  16967, 16977, 16978, 16984, 16990, 17009.
+  16967, 16977, 16978, 16984, 16990, 17009, 17042.
 
 * The minimum Linux kernel version that this version of the GNU C Library
   can be used with is 2.6.32.