src/java.base/share/classes/java/lang/FdLibm.java

@@ -180,11 +180,11 @@
             if ((ha - hb) > 0x3c00000) {
                 return a + b;  // x / y > 2**60
             }
 
             int k = 0;
-            if (a > 0x1.0p500) {   // a > 2**500
+            if (a > 0x1.00000_ffff_ffffp500) {   // a > ~2**500
                 // scale a and b by 2**-600
                 ha -= 0x25800000;
                 hb -= 0x25800000;
                 a = a * TWO_MINUS_600;
                 b = b * TWO_MINUS_600;