| Message ID | Pine.LNX.4.64.1406242024001.21652@digraph.polyomino.org.uk |
|---|---|
| State | New |
| Headers | show |
On 06/24/2014 10:24 PM, Joseph S. Myers wrote: > 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. > > (auto-libm-test-out diffs omitted below.) > > 2014-06-24 Joseph Myers <joseph@codesourcery.com> > > [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. > > diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in > index 4eaa013..79d276c 100644 > --- a/math/auto-libm-test-in > +++ b/math/auto-libm-test-in > @@ -803,6 +803,16 @@ erf 0x1.c5bf94p-127 > erf 0x3.8b7fa8p-128 > erf -0x3.8b7f12369ded8p-1024 > erf 0x3.8b7f12369ded5518p-16384 > +erf 26.0 > +erf 28.0 > +erf 100 > +erf 106 > +erf 106.5 > +erf 106.625 > +erf 107 > +erf 108 > +erf 1000 > +erf max > > erfc 0.0 > erfc -0 > diff --git a/sysdeps/ieee754/ldbl-128/s_erfl.c b/sysdeps/ieee754/ldbl-128/s_erfl.c > index 35ca8c1..f44d481 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; Could you add a comment on this, please? Fine with this change, Andreas > y = __erfcl (x); > return (one - y); > /* return (one - __erfcl (x)); */ >
diff --git a/math/auto-libm-test-in b/math/auto-libm-test-in index 4eaa013..79d276c 100644 --- a/math/auto-libm-test-in +++ b/math/auto-libm-test-in @@ -803,6 +803,16 @@ erf 0x1.c5bf94p-127 erf 0x3.8b7fa8p-128 erf -0x3.8b7f12369ded8p-1024 erf 0x3.8b7f12369ded5518p-16384 +erf 26.0 +erf 28.0 +erf 100 +erf 106 +erf 106.5 +erf 106.625 +erf 107 +erf 108 +erf 1000 +erf max erfc 0.0 erfc -0 diff --git a/sysdeps/ieee754/ldbl-128/s_erfl.c b/sysdeps/ieee754/ldbl-128/s_erfl.c index 35ca8c1..f44d481 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; y = __erfcl (x); return (one - y); /* return (one - __erfcl (x)); */