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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