Refactor according to gates.

- Fix: `IsNotTypeSlot` check in `PyObjectLookupAttr` contained a boolean logic error which led to viewing every attribute
  not named "mro" as a non-type-slot attribute. It has now been converted into the easier readable `IsTypeSlot`.
- Update: For the comparison to the string constant marker `NOT_SET` an object identity check is applicable (as argued
  in previous commits), the `Object.equals()` check which implements this without the compiler warning of a String comparison
  with `==` needs to be moved behind a Truffle boundary.

Author: phoeinx

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/csv/CSVModuleBuiltins.java

@@ -82,6 +82,7 @@
 import com.oracle.graal.python.nodes.util.CannotCastException;
 import com.oracle.graal.python.nodes.util.CastToJavaStringNode;
 import com.oracle.graal.python.runtime.object.PythonObjectFactory;
+import com.oracle.graal.python.util.PythonUtils;
 import com.oracle.truffle.api.dsl.Cached;
 import com.oracle.truffle.api.dsl.GenerateNodeFactory;
 import com.oracle.truffle.api.dsl.NodeFactory;
@@ -202,7 +203,6 @@ public abstract static class CSVListDialectsNode extends PythonBuiltinNode {
         @Specialization
         PList listDialects(VirtualFrame frame, PythonModule module,
                         @Cached ReadAttributeFromObjectNode readNode,
-                        @CachedLibrary(limit = "1") HashingStorageLibrary library,
                         @Cached ListNodes.ConstructListNode constructListNode) {
 
             Object dialects = readNode.execute(module, "_dialects");
@@ -543,9 +543,8 @@ private String getCharOrNone(String attribute, Object valueObj, String defaultVa
             if (valueObj == PNone.NO_VALUE) {
                 return defaultValue;
             }
-            if (valueObj == PNone.NONE || valueObj == NOT_SET) {
+            if (valueObj == PNone.NONE || PythonUtils.equals(valueObj, NOT_SET)) {
                 return NOT_SET;
-
             }
 
             return getChar(attribute, valueObj, defaultValue, getType, castToJavaStringNode);

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

@@ -122,9 +122,8 @@ protected static final boolean isBuiltinTypeType(Object type) {
         return type == PythonBuiltinClassType.PythonClass;
     }
 
-    protected static final boolean isNotTypeSlot(String name) {
-        final int length = name.length();
-        return length < 3 || (length > 3 && name.charAt(0) != '_') || !name.equals("mro");
+    protected static final boolean isTypeSlot(String name) {
+        return SpecialMethodSlot.canBeSpecial(name) || name.equals("mro");
     }
 
     // simple version that needs no calls and only reads from the object directly
@@ -179,7 +178,7 @@ static final Object doBuiltinModule(VirtualFrame frame, Object object, String na
     // difference for type.__getattribute__ over object.__getattribute__ is that it looks for a
     // __get__ method on the value and invokes it if it is callable.
     @SuppressWarnings("unused")
-    @Specialization(guards = {"isTypeGetAttribute(type)", "isBuiltinTypeType(type)", "isNotTypeSlot(name)"}, limit = "1")
+    @Specialization(guards = {"isTypeGetAttribute(type)", "isBuiltinTypeType(type)", "!isTypeSlot(name)"}, limit = "1")
     static final Object doBuiltinTypeType(VirtualFrame frame, Object object, String name,
                     @Cached GetClassNode getClass,
                     @Bind("getClass.execute(object)") Object type,

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/util/PythonUtils.java

@@ -586,6 +586,11 @@ public static boolean bufferHasRemaining(ByteBuffer buffer) {
         return buffer.hasRemaining();
     }
 
+    @TruffleBoundary(allowInlining = true)
+    public static boolean equals(Object a, Object b) {
+        return a.equals(b);
+    }
+
     @TruffleBoundary
     public static <E> ArrayDeque<E> newDeque() {
         return new ArrayDeque<>();