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| author | Joseph Myers <joseph@codesourcery.com> | 2014-06-24 20:56:56 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2014-06-24 20:56:56 +0000 |
| commit | e7dd3c8c1db8c6d293abb995e033893b7328ad19 (patch) | |
| tree | dcfbd9476c52dbccdedf8d691b37b7442199a756 /sysdeps/ieee754 | |
| parent | 0ea5d373c7984a1da2d0e990c6e78e6d6c24f91b (diff) | |
| download | glibc-e7dd3c8c1db8c6d293abb995e033893b7328ad19.tar.gz glibc-e7dd3c8c1db8c6d293abb995e033893b7328ad19.tar.xz glibc-e7dd3c8c1db8c6d293abb995e033893b7328ad19.zip | |
Fix ldbl-128 erfl spurious underflows (bug 16287).
This patch fixes bug 16287, spurious underflows from ldbl-128 erfl arising from it calling erfcl for arguments with absolute value at least 1.0, although for large positive arguments erfcl correctly underflows but erfl shouldn't. The fix is simply to avoid calling erfcl, and just return 1, for arguments above a cut-off large enough that erfl correctly rounds to-nearest as 1 but not so large that erfcl underflows. Tested mips64. Also tested x86_64 and x86 to confirm the new tests (taken from the tests of erfc) don't cause any problems there; no ulps updates needed. [BZ #16287] * sysdeps/ieee754/ldbl-128/s_erfl.c (__erfl): Return 1 without calling __erfcl for arguments at least 16. * math/auto-libm-test-in: Add more tests of erf. * math/auto-libm-test-out: Regenerated.
Diffstat (limited to 'sysdeps/ieee754')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128/s_erfl.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-128/s_erfl.c b/sysdeps/ieee754/ldbl-128/s_erfl.c index 35ca8c1360..9bfc9c580b 100644 --- a/sysdeps/ieee754/ldbl-128/s_erfl.c +++ b/sysdeps/ieee754/ldbl-128/s_erfl.c @@ -769,6 +769,8 @@ __erfl (long double x) if (ix >= 0x3fff0000) /* |x| >= 1.0 */ { + if (ix >= 0x40030000 && sign > 0) + return one; /* x >= 16, avoid spurious underflow from erfc. */ y = __erfcl (x); return (one - y); /* return (one - __erfcl (x)); */ |