add a simpler guard for checking for builtin lists, tuples, and dicts

Author: timfel

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

@@ -73,32 +73,29 @@
 public abstract class PyObjectGetItem extends PNodeWithContext {
     public abstract Object execute(Frame frame, Object object, Object key);
 
-    @Specialization(guards = "cannotBeOverridden(object, getClassNode)", limit = "1")
+    @Specialization(guards = "cannotBeOverriddenForImmutableType(object)")
     Object doList(VirtualFrame frame, PList object, Object key,
-                    @SuppressWarnings("unused") @Shared("getClass") @Cached GetClassNode getClassNode,
                     @Cached ListBuiltins.GetItemNode getItemNode) {
         return getItemNode.execute(frame, object, key);
     }
 
-    @Specialization(guards = "cannotBeOverridden(object, getClassNode)", limit = "1")
+    @Specialization(guards = "cannotBeOverriddenForImmutableType(object)")
     Object doTuple(VirtualFrame frame, PTuple object, Object key,
-                    @SuppressWarnings("unused") @Shared("getClass") @Cached GetClassNode getClassNode,
                     @Cached TupleBuiltins.GetItemNode getItemNode) {
         return getItemNode.execute(frame, object, key);
     }
 
     @InliningCutoff // TODO: inline this probably?
-    @Specialization(guards = "cannotBeOverridden(object, getClassNode)", limit = "1")
+    @Specialization(guards = "cannotBeOverriddenForImmutableType(object)")
     Object doDict(VirtualFrame frame, PDict object, Object key,
-                    @SuppressWarnings("unused") @Shared("getClass") @Cached GetClassNode getClassNode,
                     @Cached DictBuiltins.GetItemNode getItemNode) {
         return getItemNode.execute(frame, object, key);
     }
 
     @InliningCutoff // no point inlining the complex case
     @Specialization(replaces = {"doList", "doTuple", "doDict"})
     Object doGeneric(VirtualFrame frame, Object object, Object key,
-                    @Shared("getClass") @Cached GetClassNode getClassNode,
+                    @Cached GetClassNode getClassNode,
                     @Cached(parameters = "GetItem") LookupSpecialMethodSlotNode lookupGetItem,
                     @Cached CallBinaryMethodNode callGetItem,
                     @Cached PyObjectGetItemClass getItemClass,

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/PGuards.java

@@ -587,6 +587,16 @@ public static boolean cannotBeOverridden(Object object, GetClassNode getClassNod
         return clazz instanceof PythonBuiltinClassType || clazz instanceof PythonBuiltinClass;
     }
 
+    /**
+     * Tests if the class of this Python object is a builtin class. This method is supposed to be
+     * used for builtin types that do not support __class__ assignment at all, so we can safely
+     * read the initialPythonClass field and assume that is the current class as well.
+     */
+    public static boolean cannotBeOverriddenForImmutableType(PythonObject object) {
+        Object clazz = object.getInitialPythonClass();
+        return clazz instanceof PythonBuiltinClassType || clazz instanceof PythonBuiltinClass;
+    }
+
     public static boolean isBuiltinDict(PDict dict) {
         /*
          * dict's __class__ cannot be reassigned and other objects cannot have their class assigned