Use the expression fabs(x+0.0)-fabs(y+0.0) instead of

                   fabs(x+0.0)+fabs(y+0.0) when mixing NaNs.  This improves
consistency of the result by making it harder for the compiler to reorder
the operands.  (FP addition is not necessarily commutative because the
order of operands makes a difference on some machines iff the operands are
both NaNs.)

2 files changed, 2 insertions, 2 deletions

diff --git a/lib/msun/src/e_hypot.c b/lib/msun/src/e_hypot.c
index 932b5db..8f1cd10 100644
--- a/lib/msun/src/e_hypot.c
+++ b/lib/msun/src/e_hypot.c
@@ -68,7 +68,7 @@ __ieee754_hypot(double x, double y)
 	   if(ha >= 0x7ff00000) {	/* Inf or NaN */
 	       u_int32_t low;
 	       /* Use original arg order iff result is NaN; quieten sNaNs. */
-	       w = fabs(x+0.0)+fabs(y+0.0);
+	       w = fabs(x+0.0)-fabs(y+0.0);
 	       GET_LOW_WORD(low,a);
 	       if(((ha&0xfffff)|low)==0) w = a;
 	       GET_LOW_WORD(low,b);
diff --git a/lib/msun/src/e_hypotf.c b/lib/msun/src/e_hypotf.c
index b760cc6..c70668e 100644
--- a/lib/msun/src/e_hypotf.c
+++ b/lib/msun/src/e_hypotf.c
@@ -37,7 +37,7 @@ __ieee754_hypotf(float x, float y)
 	if(ha > 0x58800000) {	/* a>2**50 */
 	   if(ha >= 0x7f800000) {	/* Inf or NaN */
 	       /* Use original arg order iff result is NaN; quieten sNaNs. */
-	       w = fabsf(x+0.0F)+fabsf(y+0.0F);
+	       w = fabsf(x+0.0F)-fabsf(y+0.0F);
 	       if(ha == 0x7f800000) w = a;
 	       if(hb == 0x7f800000) w = b;
 	       return w;