fast path for PInt in PyNumberIndexNode

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/lib/PyNumberIndexNode.java

@@ -95,6 +95,11 @@ static long doLong(long object) {
         return object;
     }
 
+    @Specialization
+    static PInt doPInt(PInt object) {
+        return object;
+    }
+
     @Specialization(rewriteOn = UnexpectedResultException.class)
     int doCallIndexInt(VirtualFrame frame, PythonAbstractObject object,
                     @Shared("callIndex") @Cached CallIndexNode callIndex,