Add some protection to ValueHashMap against hashes with the same less significant bits

h2/src/main/org/h2/util/ValueHashMap.java

@@ -54,7 +54,12 @@ public class ValueHashMap<V> extends HashBase {
     }
 
     private int getIndex(Value key) {
-        return key.hashCode() & mask;
+        int h = key.hashCode();
+        /*
+         * Add some protection against hashes with the same less significant bits
+         * (ValueDouble with integer values, for example).
+         */
+        return (h ^ h >>> 16) & mask;
     }
 
     /**

h2/src/main/org/h2/value/ValueDouble.java

@@ -133,8 +133,12 @@ public class ValueDouble extends Value {
 
     @Override
     public int hashCode() {
-        long hash = Double.doubleToLongBits(value);
-        return (int) (hash ^ (hash >> 32));
+        /*
+         * NaNs are normalized in get() method, so it's safe to use
+         * doubleToRawLongBits() instead of doubleToLongBits() here.
+         */
+        long hash = Double.doubleToRawLongBits(value);
+        return (int) (hash ^ (hash >>> 32));
     }
 
     @Override