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| author | Joseph Myers <joseph@codesourcery.com> | 2015-06-21 18:43:10 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2015-06-21 18:43:10 +0000 |
| commit | cb0937b299182e78307795081489ec1f148bdbd7 (patch) | |
| tree | 32137f8b8dde65185697602763252a45e40e8472 /ChangeLog | |
| parent | fea1d8d67363c8b675a4c2533769ae12dc86efff (diff) | |
| download | glibc-cb0937b299182e78307795081489ec1f148bdbd7.zip glibc-cb0937b299182e78307795081489ec1f148bdbd7.tar.gz glibc-cb0937b299182e78307795081489ec1f148bdbd7.tar.bz2 | |
Fix x86_64 / x86 expm1l (-min_subnorm) result sign (bug 18569).
In the x86 / x86_64 implementations of expm1l, when expm1l's result
should underflow to 0 (argument minus the least subnormal, in some
rounding modes), it can be a zero of the wrong sign. This patch fixes
this by returning the argument with underflow forced in that case
(this is a 1ulp error relative to the correctly rounded result of -0,
which is OK in terms of the documented accuracy goals, whereas a
result with the wrong sign never is).
Tested for x86_64 and x86.
[BZ #18569]
* sysdeps/i386/fpu/e_expl.S (IEEE754_EXPL) [USE_AS_EXPM1L]: Force
underflow and return argument in case of subnormal argument.
* sysdeps/x86_64/fpu/e_expl.S (IEEE754_EXPL) [USE_AS_EXPM1L]:
Likewise.
* math/auto-libm-test-in: Add more tests of expm1.
* math/auto-libm-test-out: Regenerated.
Diffstat (limited to 'ChangeLog')
| -rw-r--r-- | ChangeLog | 8 |
1 files changed, 8 insertions, 0 deletions
@@ -1,5 +1,13 @@ 2015-06-21 Joseph Myers <joseph@codesourcery.com> + [BZ #18569] + * sysdeps/i386/fpu/e_expl.S (IEEE754_EXPL) [USE_AS_EXPM1L]: Force + underflow and return argument in case of subnormal argument. + * sysdeps/x86_64/fpu/e_expl.S (IEEE754_EXPL) [USE_AS_EXPM1L]: + Likewise. + * math/auto-libm-test-in: Add more tests of expm1. + * math/auto-libm-test-out: Regenerated. + [BZ #16361] * sysdeps/i386/fpu/e_expl.S [!USE_AS_EXPM1L] (cmin): New object. (IEEE754_EXPL) [!USE_AS_EXPM1L]: Force underflow exception for |