Fix __getattr__ handling in uncached path

Author: msimacek

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

@@ -89,7 +89,12 @@ static Object getDynamicAttr(Frame frame, Object receiver, Object name,
             Object result = PyObjectLookupAttr.readAttributeQuickly(type, getattribute, receiver, name);
             if (result != null) {
                 if (result == PNone.NO_VALUE) {
-                    throw PRaiseNode.getUncached().raise(PythonBuiltinClassType.AttributeError, ErrorMessages.OBJ_P_HAS_NO_ATTR_S, receiver, name);
+                    Object getattr = lookupGetattr.execute(frame, type, receiver);
+                    if (getattr != PNone.NO_VALUE) {
+                        return callGetattr.executeObject(frame, getattr, receiver, name);
+                    } else {
+                        throw PRaiseNode.getUncached().raise(PythonBuiltinClassType.AttributeError, ErrorMessages.OBJ_P_HAS_NO_ATTR_S, receiver, name);
+                    }
                 }
                 return result;
             }

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

@@ -254,7 +254,14 @@ static Object getDynamicAttr(Frame frame, Object receiver, Object name,
             // It pays to try this in the uncached case, avoiding a full call to __getattribute__
             Object result = readAttributeQuickly(type, getattribute, receiver, name);
             if (result != null) {
-                return result;
+                if (result == PNone.NO_VALUE) {
+                    Object getattr = lookupGetattr.execute(frame, type, receiver);
+                    if (getattr != PNone.NO_VALUE) {
+                        return callGetattr.executeObject(frame, getattr, receiver, name);
+                    } else {
+                        return null;
+                    }
+                }
             }
         }
         try {
@@ -296,7 +303,8 @@ public static PyObjectLookupAttr getUncached() {
      * ModuleBuiltins.GetAttributeNode}. This method returns {@code PNone.NO_VALUE} when the
      * attribute is not found and the original would've raised an AttributeError. It returns {@code
      * null} when no shortcut was applicable. If {@code PNone.NO_VALUE} was returned, name is
-     * guaranteed to be a {@code java.lang.String}.
+     * guaranteed to be a {@code java.lang.String}. Note it is often necessary to call
+     * {@code __getattr__} if this returns {@code PNone.NO_VALUE}.
      */
     static final Object readAttributeQuickly(Object type, Object getattribute, Object receiver, Object name) {
         if (name instanceof String) {