about summary refs log tree commit diff
path: root/NEWS
diff options
context:
space:
mode:
authorJoseph Myers <joseph@codesourcery.com>2014-05-14 12:35:40 +0000
committerJoseph Myers <joseph@codesourcery.com>2014-05-14 12:35:40 +0000
commit913d03c864ea2547e97f8d2d30fc71a008d4d103 (patch)
treef5b230d8c416181ef9998a5cf497d7cd89091b72 /NEWS
parent0bf061d3e37e0f72c2378cbded67c58df4f58a4b (diff)
downloadglibc-913d03c864ea2547e97f8d2d30fc71a008d4d103.tar.gz
glibc-913d03c864ea2547e97f8d2d30fc71a008d4d103.tar.xz
glibc-913d03c864ea2547e97f8d2d30fc71a008d4d103.zip
Fix acosh (1) in round-downward mode (bug 16927).
According to C99 and C11 Annex F, acosh (1) should be +0 in all
rounding modes.  However, some implementations in glibc wrongly return
-0 in round-downward mode (which is what you get if you end up
computing log1p (-0), via 1 - 1 being -0 in round-downward mode).
This patch fixes the problem implementations, by correcting the test
for an exact 1 value in the ldbl-96 implementation to allow for the
explicit high bit of the mantissa, and by inserting fabs instructions
in the i386 implementations; tests of acosh are duly converted to
ALL_RM_TEST.  I believe all the other sysdeps/ieee754 implementations
are already OK (I haven't checked the ia64 versions, but if buggy then
that will be obvious from the results of test runs after this patch is
in).

Tested x86_64 and x86 and ulps updated accordingly.

	[BZ #16927]
	* sysdeps/i386/fpu/e_acosh.S (__ieee754_acosh): Use fabs on x-1
	value.
	* sysdeps/i386/fpu/e_acoshf.S (__ieee754_acoshf): Likewise.
	* sysdeps/i386/fpu/e_acoshl.S (__ieee754_acoshl): Likewise.
	* sysdeps/ieee754/ldbl-96/e_acoshl.c (__ieee754_acoshl): Correct
	for explicit high bit of mantissa when testing for argument equal
	to 1.
	* math/libm-test.inc (acosh_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 9293f802f8..974d2c80a9 100644
--- a/NEWS
+++ b/NEWS
@@ -17,7 +17,7 @@ Version 2.20
   16713, 16714, 16731, 16739, 16740, 16743, 16754, 16758, 16759, 16760,
   16770, 16786, 16789, 16791, 16799, 16800, 16815, 16823, 16824, 16831,
   16838, 16854, 16876, 16877, 16885, 16888, 16890, 16912, 16916, 16922,
-  16932.
+  16927, 16932.
 
 * The minimum Linux kernel version that this version of the GNU C Library
   can be used with is 2.6.32.