--- a/libquadmath/math/scalblnq.c	Sun Aug 21 07:07:55 2011 +0900
+++ b/libquadmath/math/scalblnq.c	Fri Oct 27 22:46:09 2017 +0900
@@ -1,7 +1,7 @@
-/* s_scalblnl.c -- long double version of s_scalbn.c.
+/* scalblnq.c -- __float128 version of s_scalbn.c.
  * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
  */
-   
+
 /*
  * ====================================================
  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
@@ -13,6 +13,13 @@
  * ====================================================
  */
 
+/*
+ * scalblnq (_float128 x, long int n)
+ * scalblnq(x,n) returns x* 2**n  computed by  exponent
+ * manipulation rather than by actually performing an
+ * exponentiation or a multiplication.
+ */
+
 #include "quadmath-imp.h"
 
 static const __float128
@@ -34,10 +41,12 @@
 	    k = ((hx>>48)&0x7fff) - 114;
 	}
         if (k==0x7fff) return x+x;		/* NaN or Inf */
+	if (n< -50000) return tiny*copysignq(tiny,x); /*underflow*/
+        if (n> 50000 || k+n > 0x7ffe)
+	  return huge*copysignq(huge,x); /* overflow  */
+	/* Now k and n are bounded we know that k = k+n does not
+	   overflow.  */
         k = k+n;
-        if (n> 50000 || k > 0x7ffe)
-	  return huge*copysignq(huge,x); /* overflow  */
-	if (n< -50000) return tiny*copysignq(tiny,x); /*underflow*/
         if (k > 0) 				/* normal result */
 	    {SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48)); return x;}
         if (k <= -114)