1 files changed, 11 insertions, 4 deletions
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_isinf_nsl.c b/sysdeps/ieee754/ldbl-128ibm/s_isinf_nsl.c
index c8dd9ff98a..54e72c9166 100644
--- a/sysdeps/ieee754/ldbl-128ibm/s_isinf_nsl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/s_isinf_nsl.c
@@ -1,6 +1,7 @@
 /*
  * __isinf_nsl(x) returns != 0 if x is ±inf, else 0;
  * no branching!
+ * slightly dodgy in relying on signed shift right copying sign bit
  */
 
 #include <math.h>
@@ -9,8 +10,14 @@
 int
 __isinf_nsl (long double x)
 {
-	int64_t hx,lx;
-	GET_LDOUBLE_WORDS64(hx,lx,x);
-	return !((lx & 0x7fffffffffffffffLL)
-		 | ((hx & 0x7fffffffffffffffLL) ^ 0x7ff0000000000000LL));
+  double xhi;
+  int64_t hx, mask;
+
+  xhi = ldbl_high (x);
+  EXTRACT_WORDS64 (hx, xhi);
+
+  mask = (hx & 0x7fffffffffffffffLL) ^ 0x7ff0000000000000LL;
+  mask |= -mask;
+  mask >>= 63;
+  return ~mask;
 }