Date: Fri, 21 Oct 2011 06:30:43 +0000 (UTC) From: David Schultz <das@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r226601 - head/lib/msun/src Message-ID: <201110210630.p9L6UhjO010032@svn.freebsd.org>
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Author: das Date: Fri Oct 21 06:30:43 2011 New Revision: 226601 URL: http://svn.freebsd.org/changeset/base/226601 Log: Fix a regression introduced in r226371: When the high part of x*y exactly cancels with z, return the low part of x*y instead of discarding it. Modified: head/lib/msun/src/s_fma.c head/lib/msun/src/s_fmal.c Modified: head/lib/msun/src/s_fma.c ============================================================================== --- head/lib/msun/src/s_fma.c Fri Oct 21 06:30:16 2011 (r226600) +++ head/lib/msun/src/s_fma.c Fri Oct 21 06:30:43 2011 (r226601) @@ -250,6 +250,8 @@ fma(double x, double y, double z) xy = dd_mul(xs, ys); r = dd_add(xy.hi, zs); + spread = ex + ey; + if (r.hi == 0.0) { /* * When the addends cancel to 0, ensure that the result has @@ -257,11 +259,9 @@ fma(double x, double y, double z) */ fesetround(oround); volatile double vzs = zs; /* XXX gcc CSE bug workaround */ - return (xy.hi + vzs); + return (xy.hi + vzs + ldexp(xy.lo, spread)); } - spread = ex + ey; - if (oround != FE_TONEAREST) { /* * There is no need to worry about double rounding in directed Modified: head/lib/msun/src/s_fmal.c ============================================================================== --- head/lib/msun/src/s_fmal.c Fri Oct 21 06:30:16 2011 (r226600) +++ head/lib/msun/src/s_fmal.c Fri Oct 21 06:30:43 2011 (r226601) @@ -238,6 +238,8 @@ fmal(long double x, long double y, long xy = dd_mul(xs, ys); r = dd_add(xy.hi, zs); + spread = ex + ey; + if (r.hi == 0.0) { /* * When the addends cancel to 0, ensure that the result has @@ -245,11 +247,9 @@ fmal(long double x, long double y, long */ fesetround(oround); volatile long double vzs = zs; /* XXX gcc CSE bug workaround */ - return (xy.hi + vzs); + return (xy.hi + vzs + ldexpl(xy.lo, spread)); } - spread = ex + ey; - if (oround != FE_TONEAREST) { /* * There is no need to worry about double rounding in directed
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