8268113: Re-use Long.hashCode() where possible

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

@@ -877,8 +877,7 @@ public int hashCode() {
      * @since 1.8
      */
     public static int hashCode(double value) {
-        long bits = doubleToLongBits(value);
-        return (int)(bits ^ (bits >>> 32));
+        return Long.hashCode(doubleToLongBits(value));
     }
 
     /**

src/java.base/share/classes/java/time/LocalTime.java

@@ -1596,8 +1596,7 @@ public boolean equals(Object obj) {
      */
     @Override
     public int hashCode() {
-        long nod = toNanoOfDay();
-        return (int) (nod ^ (nod >>> 32));
+        return Long.hashCode(toNanoOfDay());
     }
 
     //-----------------------------------------------------------------------

src/java.base/share/classes/java/time/temporal/ValueRange.java

@@ -410,7 +410,7 @@ public int hashCode() {
         long hash = minSmallest + (minLargest << 16) + (minLargest >> 48) +
                 (maxSmallest << 32) + (maxSmallest >> 32) + (maxLargest << 48) +
                 (maxLargest >> 16);
-        return (int) (hash ^ (hash >>> 32));
+        return Long.hashCode(hash);
     }
 
     //-----------------------------------------------------------------------

src/java.base/share/classes/java/util/BitSet.java

@@ -96,13 +96,13 @@ public class BitSet implements Cloneable, java.io.Serializable {
     /**
      * The number of words in the logical size of this BitSet.
      */
-    private transient int wordsInUse = 0;
+    private transient int wordsInUse;
 
     /**
      * Whether the size of "words" is user-specified.  If so, we assume
      * the user knows what he's doing and try harder to preserve it.
      */
-    private transient boolean sizeIsSticky = false;
+    private transient boolean sizeIsSticky;
 
     /* use serialVersionUID from JDK 1.0.2 for interoperability */
     @java.io.Serial
@@ -1037,7 +1037,7 @@ public int hashCode() {
         for (int i = wordsInUse; --i >= 0; )
             h ^= words[i] * (i + 1);
 
-        return (int)((h >> 32) ^ h);
+        return Long.hashCode(h);
     }
 
     /**

src/java.desktop/macosx/classes/apple/laf/JRSUIConstants.java

@@ -111,8 +111,7 @@ public boolean equals(final Object obj) {
         }
 
         public int hashCode() {
-            final long bits = Double.doubleToLongBits(doubleValue);
-            return (int)(bits ^ (bits >>> 32));
+            return Double.hashCode(doubleValue);
         }
 
         public String toString() {

src/java.xml/share/classes/com/sun/org/apache/xerces/internal/impl/dv/xs/DoubleDV.java

@@ -123,8 +123,7 @@ public int hashCode() {
             if (value == 0d) {
                 return 0;
             }
-            long v = Double.doubleToLongBits(value);
-            return (int) (v ^ (v >>> 32));
+            return Double.hashCode(value);
         }
 
         // NOTE: 0.0 is equal but not identical to -0.0

src/jdk.jshell/share/classes/jdk/internal/jshell/tool/Selector.java

@@ -276,7 +276,7 @@ public boolean equals(Object o) {
 
     @Override
     public int hashCode() {
-        return (int) (asBits() ^ (asBits() >>> 32));
+        return Long.hashCode(asBits());
     }
 
     /**