Implement the identity interop trait for both ImmutableRubyObject and RubyDynamicObject

* Consistently with what's used for the default Kernel#hash.

Author: eregon

spec/truffle/interop/special_forms_spec.rb

@@ -304,7 +304,7 @@
 
   it description['.object_id', :identityHashCode, [], 'when `hasIdentity()` is true (which might not be unique)'] do
     pfo, obj, l = proxy[Object.new]
-    pfo.object_id.should == obj.object_id
+    pfo.object_id.should == Truffle::Interop.identity_hash_code(obj)
     l.log.should include(["isIdentical", pfo, :InteropLibrary]) # hasIdentity()
     l.log.should include(["identityHashCode"])
   end
@@ -318,7 +318,7 @@
 
   it description['.__id__', :identityHashCode, [], 'when `hasIdentity()` is true (which might not be unique)'] do
     pfo, obj, l = proxy[Object.new]
-    pfo.__id__.should == obj.__id__
+    pfo.__id__.should == Truffle::Interop.identity_hash_code(obj)
     l.log.should include(["isIdentical", pfo, :InteropLibrary]) # hasIdentity()
     l.log.should include(["identityHashCode"])
   end
@@ -332,7 +332,7 @@
 
   it description['.hash', :identityHashCode, [], 'when `hasIdentity()` is true (which might not be unique)'] do
     pfo, obj, l = proxy[Object.new]
-    pfo.hash.should == obj.__id__
+    pfo.hash.should == Truffle::Interop.identity_hash_code(obj)
     l.log.should include(["isIdentical", pfo, :InteropLibrary]) # hasIdentity()
     l.log.should include(["identityHashCode"])
   end

src/main/java/org/truffleruby/language/ImmutableRubyObject.java

@@ -11,6 +11,8 @@
 
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.library.CachedLibrary;
+import com.oracle.truffle.api.profiles.ConditionProfile;
+import com.oracle.truffle.api.utilities.TriState;
 import org.truffleruby.RubyContext;
 import org.truffleruby.RubyLanguage;
 import org.truffleruby.cext.ValueWrapper;
@@ -84,6 +86,23 @@ public String toDisplayString(boolean allowSideEffects) {
         throw new AbstractMethodError();
     }
 
+    // region Identity
+    @ExportMessage
+    public int identityHashCode() {
+        return System.identityHashCode(this);
+    }
+
+    @ExportMessage
+    public TriState isIdenticalOrUndefined(Object other,
+            @Exclusive @Cached ConditionProfile immutableRubyObjectProfile) {
+        if (immutableRubyObjectProfile.profile(other instanceof ImmutableRubyObject)) {
+            return TriState.valueOf(this == other);
+        } else {
+            return TriState.UNDEFINED;
+        }
+    }
+    // endregion
+
     // region Members
     @ExportMessage
     public boolean hasMembers() {

src/main/java/org/truffleruby/language/RubyDynamicObject.java

@@ -15,7 +15,6 @@
 import org.truffleruby.RubyContext;
 import org.truffleruby.RubyLanguage;
 import org.truffleruby.core.array.ArrayUtils;
-import org.truffleruby.core.basicobject.BasicObjectNodes.ObjectIDNode;
 import org.truffleruby.core.cast.BooleanCastNode;
 import org.truffleruby.core.cast.IntegerCastNode;
 import org.truffleruby.core.cast.LongCastNode;
@@ -139,19 +138,16 @@ public Object toDisplayString(boolean allowSideEffects,
     }
 
     // region Identity
-    /** Like {@link org.truffleruby.core.hash.HashingNodes} but simplified since {@link ObjectIDNode} for
-     * RubyDynamicObject can only return long. */
     @ExportMessage
-    public int identityHashCode(
-            @Cached ObjectIDNode objectIDNode) {
-        return (int) objectIDNode.execute(this);
+    public int identityHashCode() {
+        return System.identityHashCode(this);
     }
 
     @ExportMessage
     public TriState isIdenticalOrUndefined(Object other,
             @Exclusive @Cached ConditionProfile rubyObjectProfile) {
         if (rubyObjectProfile.profile(other instanceof RubyDynamicObject)) {
-            return this == other ? TriState.TRUE : TriState.FALSE;
+            return TriState.valueOf(this == other);
         } else {
             return TriState.UNDEFINED;
         }