> Date: Mon, 2 Jun 2014 10:17:53 +0200 (CEST) > From: Mark Kettenis <mark.kette...@xs4all.nl> > > > Date: Mon, 02 Jun 2014 09:34:20 +0200 > > From: Benjamin Baier <program...@netzbasis.de> > > > > You might want to read up on floating point arithmetic. (rounding and > > representation) > > Well, the difference between 4.994404 and 5.0 is a bit large to blame > rounding and binary representation. And other OpenBSD platforms > (amd64, sparc64, powerpc) return the expected result. So I'd say that > there is a bug in the i386-specific implementation of exp2(3).
And here is a fix. There actually isn't any i386-specific code, but i386 is "special" and needs STRICT_ALIGN() to work properly for double as well as float. FreeBSD made the same change a while ago: http://svnweb.FreeBSD.org/base/head/lib/msun/src/math_private.h?revision=240827&view=markup Haven't run the regression tests yet with this change. Index: src/math_private.h =================================================================== RCS file: /cvs/src/lib/libm/src/math_private.h,v retrieving revision 1.16 diff -u -p -r1.16 math_private.h --- src/math_private.h 12 Nov 2013 20:35:09 -0000 1.16 +++ src/math_private.h 2 Jun 2014 09:30:13 -0000 @@ -349,7 +349,7 @@ do { \ #define STRICT_ASSIGN(type, lval, rval) do { \ volatile type __lval; \ \ - if (sizeof(type) >= sizeof(double)) \ + if (sizeof(type) >= sizeof(long double)) \ (lval) = (rval); \ else { \ __lval = (rval); \
