Currently, in the intrinsic for Object::hashCode or System::identityHashCode, we perform a read of the mark word/object header. This load is not constant and cannot be eliminated. As a result, we cannot evaluate the identity hash code of a constant object as a constant value.

Evaluating the hash of a constant as a constant would be helpful for certain workloads: for example, if a call uses class literals to look up in a map, and the map supports constant folding, if the class hash becomes a constant, the whole map lookup can get eliminated.

We can easily add a shortcut to constant-fold a hash value for an object to provide such benefits.