Merge pull request #950 from undingen/rewritable

use a template to remove rewriter checks inside our most important runtime funcs

src/capi/abstract.cpp

@@ -758,7 +758,7 @@ exit:
 }
 
 extern "C" Py_ssize_t PyObject_Size(PyObject* o) noexcept {
-    BoxedInt* r = lenInternal<ExceptionStyle::CAPI>(o, NULL);
+    BoxedInt* r = lenInternal<ExceptionStyle::CAPI, NOT_REWRITABLE>(o, NULL);
     if (!r)
         return -1;
     return r->n;
@@ -2252,7 +2252,7 @@ extern "C" PyObject* PyNumber_Int(PyObject* o) noexcept {
     // Pyston change: this should be an optimization
     // PyObject* trunc_func = PyObject_GetAttrString(o, "__trunc__");
     static BoxedString* trunc_str = internStringImmortal("__trunc__");
-    PyObject* trunc_func = getattrInternal<ExceptionStyle::CAPI>(o, trunc_str, NULL);
+    PyObject* trunc_func = getattrInternal<ExceptionStyle::CAPI>(o, trunc_str);
 
     if (trunc_func) {
         PyObject* truncated = PyEval_CallObject(trunc_func, NULL);

src/capi/object.cpp

@@ -486,7 +486,7 @@ extern "C" int PyObject_GenericSetAttr(PyObject* obj, PyObject* name, PyObject*
         if (value == NULL)
             delattrGeneric(obj, str, NULL);
         else
-            setattrGeneric(obj, str, value, NULL);
+            setattrGeneric<NOT_REWRITABLE>(obj, str, value, NULL);
     } catch (ExcInfo e) {
         setCAPIException(e);
         return -1;
@@ -534,7 +534,7 @@ extern "C" int PyObject_SetAttrString(PyObject* v, const char* name, PyObject* w
 
 extern "C" PyObject* PyObject_GetAttrString(PyObject* o, const char* attr) noexcept {
     try {
-        Box* r = getattrInternal<ExceptionStyle::CXX>(o, internStringMortal(attr), NULL);
+        Box* r = getattrInternal<ExceptionStyle::CXX>(o, internStringMortal(attr));
         if (!r)
             PyErr_Format(PyExc_AttributeError, "'%.50s' object has no attribute '%.400s'", o->cls->tp_name, attr);
         return r;

src/capi/typeobject.cpp

@@ -484,7 +484,7 @@ static PyObject* lookup_maybe(PyObject* self, const char* attrstr, PyObject** at
             return NULL;
     }
 
-    Box* obj = typeLookup(self->cls, (BoxedString*)*attrobj, NULL);
+    Box* obj = typeLookup(self->cls, (BoxedString*)*attrobj);
     if (obj) {
         try {
             return processDescriptor(obj, self, self->cls);
@@ -809,7 +809,7 @@ static PyObject* slot_tp_descr_get(PyObject* self, PyObject* obj, PyObject* type
     PyObject* get;
 
     static BoxedString* get_str = internStringImmortal("__get__");
-    get = typeLookup(tp, get_str, NULL);
+    get = typeLookup(tp, get_str);
     if (get == NULL) {
         /* Avoid further slowdowns */
         if (tp->tp_descr_get == slot_tp_descr_get)
@@ -883,11 +883,16 @@ static PyObject* call_attribute(PyObject* self, PyObject* attr, PyObject* name)
 
 /* Pyston change: static */ PyObject* slot_tp_getattr_hook(PyObject* self, PyObject* name) noexcept {
     assert(name->cls == str_cls);
-    return slotTpGetattrHookInternal<CAPI>(self, (BoxedString*)name, NULL);
+    return slotTpGetattrHookInternal<CAPI, NOT_REWRITABLE>(self, (BoxedString*)name, NULL);
 }
 
-template <ExceptionStyle S>
+template <ExceptionStyle S, Rewritable rewritable>
 Box* slotTpGetattrHookInternal(Box* self, BoxedString* name, GetattrRewriteArgs* rewrite_args) noexcept(S == CAPI) {
+    if (rewritable == NOT_REWRITABLE) {
+        assert(!rewrite_args);
+        rewrite_args = NULL;
+    }
+
     STAT_TIMER(t0, "us_timer_slot_tpgetattrhook", SLOT_AVOIDABILITY(self));
 
     PyObject* getattr, *getattribute, * res = NULL;
@@ -905,7 +910,7 @@ Box* slotTpGetattrHookInternal(Box* self, BoxedString* name, GetattrRewriteArgs*
     // - if we never get to the "call __getattr__" portion and the "calling __getattribute__"
     //   portion still has its guards pass, then that section is still behaviorally correct, and
     //   I think should be close to as fast as the normal rewritten version we would generate.
-    getattr = typeLookup(self->cls, _getattr_str, NULL);
+    getattr = typeLookup(self->cls, _getattr_str);
 
     if (getattr == NULL) {
         if (rewrite_args) {
@@ -943,7 +948,7 @@ Box* slotTpGetattrHookInternal(Box* self, BoxedString* name, GetattrRewriteArgs*
             grewrite_args.assertReturnConvention(ReturnConvention::NO_RETURN);
         }
     } else {
-        getattribute = typeLookup(self->cls, _getattribute_str, NULL);
+        getattribute = typeLookup(self->cls, _getattribute_str);
     }
 
     // Not sure why CPython checks if getattribute is NULL since I don't think that should happen.
@@ -966,7 +971,7 @@ Box* slotTpGetattrHookInternal(Box* self, BoxedString* name, GetattrRewriteArgs*
             GetattrRewriteArgs grewrite_args(rewrite_args->rewriter, rewrite_args->obj, rewrite_args->destination);
             try {
                 assert(!PyType_Check(self)); // There would be a getattribute
-                res = getattrInternalGeneric<false>(self, name, &grewrite_args, false, false, NULL, NULL);
+                res = getattrInternalGeneric<false, rewritable>(self, name, &grewrite_args, false, false, NULL, NULL);
             } catch (ExcInfo e) {
                 if (!e.matches(AttributeError)) {
                     if (S == CAPI) {
@@ -1013,7 +1018,7 @@ Box* slotTpGetattrHookInternal(Box* self, BoxedString* name, GetattrRewriteArgs*
         } else {
             try {
                 assert(!PyType_Check(self)); // There would be a getattribute
-                res = getattrInternalGeneric<false>(self, name, NULL, false, false, NULL, NULL);
+                res = getattrInternalGeneric<false, rewritable>(self, name, NULL, false, false, NULL, NULL);
             } catch (ExcInfo e) {
                 if (!e.matches(AttributeError)) {
                     if (S == CAPI) {
@@ -1068,8 +1073,8 @@ Box* slotTpGetattrHookInternal(Box* self, BoxedString* name, GetattrRewriteArgs*
         assert(PyString_CHECK_INTERNED(name) == SSTATE_INTERNED_IMMORTAL);
         crewrite_args.arg1 = rewrite_args->rewriter->loadConst((intptr_t)name, Location::forArg(1));
 
-        res = callattrInternal<S>(self, _getattr_str, LookupScope::CLASS_ONLY, &crewrite_args, ArgPassSpec(1), name,
-                                  NULL, NULL, NULL, NULL);
+        res = callattrInternal<S, REWRITABLE>(self, _getattr_str, LookupScope::CLASS_ONLY, &crewrite_args,
+                                              ArgPassSpec(1), name, NULL, NULL, NULL, NULL);
         assert(res || S == CAPI);
 
         if (!crewrite_args.isSuccessful())
@@ -1083,16 +1088,22 @@ Box* slotTpGetattrHookInternal(Box* self, BoxedString* name, GetattrRewriteArgs*
         // the rewrite_args and non-rewrite_args case the same.
         // Actually, we might have gotten to the point that doing a runtimeCall on an instancemethod is as
         // fast as a callattr, but that hasn't typically been the case.
-        res = callattrInternal<S>(self, _getattr_str, LookupScope::CLASS_ONLY, NULL, ArgPassSpec(1), name, NULL, NULL,
-                                  NULL, NULL);
+        res = callattrInternal<S, NOT_REWRITABLE>(self, _getattr_str, LookupScope::CLASS_ONLY, NULL, ArgPassSpec(1),
+                                                  name, NULL, NULL, NULL, NULL);
         assert(res || S == CAPI);
     }
 
     return res;
 }
 // Force instantiation of the template
-template Box* slotTpGetattrHookInternal<CAPI>(Box* self, BoxedString* name, GetattrRewriteArgs* rewrite_args);
-template Box* slotTpGetattrHookInternal<CXX>(Box* self, BoxedString* name, GetattrRewriteArgs* rewrite_args);
+template Box* slotTpGetattrHookInternal<CAPI, REWRITABLE>(Box* self, BoxedString* name,
+                                                          GetattrRewriteArgs* rewrite_args);
+template Box* slotTpGetattrHookInternal<CXX, REWRITABLE>(Box* self, BoxedString* name,
+                                                         GetattrRewriteArgs* rewrite_args);
+template Box* slotTpGetattrHookInternal<CAPI, NOT_REWRITABLE>(Box* self, BoxedString* name,
+                                                              GetattrRewriteArgs* rewrite_args);
+template Box* slotTpGetattrHookInternal<CXX, NOT_REWRITABLE>(Box* self, BoxedString* name,
+                                                             GetattrRewriteArgs* rewrite_args);
 
 /* Pyston change: static */ PyObject* slot_tp_new(PyTypeObject* self, PyObject* args, PyObject* kwds) noexcept {
     STAT_TIMER(t0, "us_timer_slot_tpnew", SLOT_AVOIDABILITY(self));
@@ -1100,7 +1111,7 @@ template Box* slotTpGetattrHookInternal<CXX>(Box* self, BoxedString* name, Getat
     try {
         // TODO: runtime ICs?
         static BoxedString* _new_str = internStringImmortal("__new__");
-        Box* new_attr = typeLookup(self, _new_str, NULL);
+        Box* new_attr = typeLookup(self, _new_str);
         assert(new_attr);
         new_attr = processDescriptor(new_attr, None, self);
 
@@ -1115,7 +1126,7 @@ static PyObject* slot_tp_del(PyObject* self) noexcept {
     static BoxedString* del_str = internStringImmortal("__del__");
     try {
         // TODO: runtime ICs?
-        Box* del_attr = typeLookup(self->cls, del_str, NULL);
+        Box* del_attr = typeLookup(self->cls, del_str);
         assert(del_attr);
 
         CallattrFlags flags{.cls_only = false,
@@ -1155,7 +1166,7 @@ static PyObject* slot_tp_del(PyObject* self) noexcept {
 
 PyObject* slot_sq_item(PyObject* self, Py_ssize_t i) noexcept {
     STAT_TIMER(t0, "us_timer_slot_sqitem", SLOT_AVOIDABILITY(self));
-    return getitemInternal<CAPI>(self, boxInt(i), NULL);
+    return getitemInternal<CAPI>(self, boxInt(i));
 }
 
 /* Pyston change: static */ Py_ssize_t slot_sq_length(PyObject* self) noexcept {
@@ -1823,7 +1834,7 @@ static const slotdef* update_one_slot(BoxedClass* type, const slotdef* p) noexce
     }
 
     do {
-        descr = typeLookup(type, p->name_strobj, NULL);
+        descr = typeLookup(type, p->name_strobj);
 
         if (p->flags & PyWrapperFlag_BOOL) {
             // We are supposed to iterate over each slotdef; for now just assert that

src/capi/typeobject.h

@@ -55,7 +55,7 @@ PyObject* tp_new_wrapper(PyTypeObject* self, BoxedTuple* args, Box* kwds) noexce
 int slot_tp_init(PyObject* self, PyObject* args, PyObject* kwds) noexcept;
 
 class GetattrRewriteArgs;
-template <ExceptionStyle S>
+template <ExceptionStyle S, Rewritable rewritable>
 Box* slotTpGetattrHookInternal(Box* self, BoxedString* attr, GetattrRewriteArgs* rewrite_args) noexcept(S == CAPI);
 }
 

src/codegen/compvars.cpp

@@ -1563,7 +1563,7 @@ public:
     CompilerType* getattrType(BoxedString* attr, bool cls_only) override {
         // Any changes here need to be mirrored in getattr()
         if (canStaticallyResolveGetattrs()) {
-            Box* rtattr = typeLookup(cls, attr, nullptr);
+            Box* rtattr = typeLookup(cls, attr);
             if (rtattr == NULL)
                 return UNDEF;
 
@@ -1588,7 +1588,7 @@ public:
                               bool cls_only) override {
         // Any changes here need to be mirrored in getattrType()
         if (canStaticallyResolveGetattrs()) {
-            Box* rtattr = typeLookup(cls, attr, nullptr);
+            Box* rtattr = typeLookup(cls, attr);
             if (rtattr == NULL) {
                 ExceptionStyle exception_style = info.preferredExceptionStyle();
                 llvm::Value* raise_func = exception_style == CXX ? g.funcs.raiseAttributeErrorStr

src/core/cfg.cpp

@@ -2625,7 +2625,7 @@ CFG* computeCFG(SourceInfo* source, std::vector<AST_stmt*> body) {
 
         if (source->scoping->areGlobalsFromModule()) {
             static BoxedString* name_str = internStringImmortal("__name__");
-            Box* module_name = source->parent_module->getattr(name_str, NULL);
+            Box* module_name = source->parent_module->getattr(name_str);
             assert(module_name->cls == str_cls);
             module_assign->value = new AST_Str(static_cast<BoxedString*>(module_name)->s());
         } else {

src/core/types.h

@@ -51,6 +51,11 @@ enum ExceptionStyle {
     CXX,
 };
 
+enum Rewritable {
+    REWRITABLE,
+    NOT_REWRITABLE,
+};
+
 template <typename T> struct ExceptionSwitchable {
 public:
     T capi_val;
@@ -545,8 +550,9 @@ public:
 
     // getattr() does the equivalent of PyDict_GetItem(obj->dict, attr): it looks up the attribute's value on the
     // object's attribute storage. it doesn't look at other objects or do any descriptor logic.
+    template <Rewritable rewritable = REWRITABLE>
     Box* getattr(BoxedString* attr, GetattrRewriteArgs* rewrite_args);
-    Box* getattr(BoxedString* attr) { return getattr(attr, NULL); }
+    Box* getattr(BoxedString* attr) { return getattr<NOT_REWRITABLE>(attr, NULL); }
     bool hasattr(BoxedString* attr) { return getattr(attr) != NULL; }
     void delattr(BoxedString* attr, DelattrRewriteArgs* rewrite_args);
 

src/runtime/builtin_modules/builtins.cpp

@@ -83,7 +83,7 @@ extern "C" Box* vars(Box* obj) {
         return fastLocalsToBoxedLocals();
 
     static BoxedString* dict_str = internStringImmortal("__dict__");
-    Box* rtn = getattrInternal<ExceptionStyle::CAPI>(obj, dict_str, NULL);
+    Box* rtn = getattrInternal<ExceptionStyle::CAPI>(obj, dict_str);
     if (!rtn)
         raiseExcHelper(TypeError, "vars() argument must have __dict__ attribute");
     return rtn;
@@ -580,7 +580,7 @@ Box* getattrFuncInternal(BoxedFunctionBase* func, CallRewriteArgs* rewrite_args,
                 r_rtn = rewrite_args->rewriter->loadConst(0);
         }
     } else {
-        rtn = getattrInternal<CAPI>(obj, str, NULL);
+        rtn = getattrInternal<CAPI>(obj, str);
     }
 
     if (rewrite_args) {
@@ -691,7 +691,7 @@ Box* hasattrFuncInternal(BoxedFunctionBase* func, CallRewriteArgs* rewrite_args,
                 r_rtn = rewrite_args->rewriter->loadConst(0);
         }
     } else {
-        rtn = getattrInternal<CAPI>(obj, str, NULL);
+        rtn = getattrInternal<CAPI>(obj, str);
     }
 
     if (rewrite_args) {
@@ -1252,7 +1252,7 @@ Box* ellipsisRepr(Box* self) {
     return boxString("Ellipsis");
 }
 Box* divmod(Box* lhs, Box* rhs) {
-    return binopInternal(lhs, rhs, AST_TYPE::DivMod, false, NULL);
+    return binopInternal<NOT_REWRITABLE>(lhs, rhs, AST_TYPE::DivMod, false, NULL);
 }
 
 Box* powFunc(Box* x, Box* y, Box* z) {
@@ -1326,7 +1326,7 @@ Box* getreversed(Box* o) {
         return r;
 
     static BoxedString* getitem_str = internStringImmortal("__getitem__");
-    if (!typeLookup(o->cls, getitem_str, NULL)) {
+    if (!typeLookup(o->cls, getitem_str)) {
         raiseExcHelper(TypeError, "'%s' object is not iterable", getTypeName(o));
     }
     int64_t len = unboxedLen(o); // this will throw an exception if __len__ isn't there

src/runtime/capi.cpp

@@ -220,7 +220,7 @@ extern "C" PyObject* PyObject_GetAttr(PyObject* o, PyObject* attr) noexcept {
     BoxedString* s = static_cast<BoxedString*>(attr);
     internStringMortalInplace(s);
 
-    Box* r = getattrInternal<ExceptionStyle::CAPI>(o, s, NULL);
+    Box* r = getattrInternal<ExceptionStyle::CAPI>(o, s);
 
     if (!r && !PyErr_Occurred()) {
         PyErr_Format(PyExc_AttributeError, "'%.50s' object has no attribute '%.400s'", o->cls->tp_name,
@@ -234,7 +234,7 @@ extern "C" PyObject* PyObject_GenericGetAttr(PyObject* o, PyObject* name) noexce
     try {
         BoxedString* s = static_cast<BoxedString*>(name);
         internStringMortalInplace(s);
-        Box* r = getattrInternalGeneric<false>(o, s, NULL, false, false, NULL, NULL);
+        Box* r = getattrInternalGeneric<false, NOT_REWRITABLE>(o, s, NULL, false, false, NULL, NULL);
         if (!r)
             PyErr_Format(PyExc_AttributeError, "'%.50s' object has no attribute '%.400s'", o->cls->tp_name,
                          PyString_AS_STRING(name));
@@ -458,7 +458,7 @@ done:
 
 
 extern "C" PyObject* PyObject_GetItem(PyObject* o, PyObject* key) noexcept {
-    return getitemInternal<ExceptionStyle::CAPI>(o, key, NULL);
+    return getitemInternal<ExceptionStyle::CAPI>(o, key);
 }
 
 extern "C" int PyObject_SetItem(PyObject* o, PyObject* key, PyObject* v) noexcept {
@@ -580,11 +580,11 @@ extern "C" int PyObject_Not(PyObject* o) noexcept {
 
 extern "C" PyObject* PyObject_Call(PyObject* callable_object, PyObject* args, PyObject* kw) noexcept {
     if (kw)
-        return runtimeCallInternal<ExceptionStyle::CAPI>(callable_object, NULL, ArgPassSpec(0, 0, true, true), args, kw,
-                                                         NULL, NULL, NULL);
+        return runtimeCallInternal<ExceptionStyle::CAPI, NOT_REWRITABLE>(
+            callable_object, NULL, ArgPassSpec(0, 0, true, true), args, kw, NULL, NULL, NULL);
     else
-        return runtimeCallInternal<ExceptionStyle::CAPI>(callable_object, NULL, ArgPassSpec(0, 0, true, false), args,
-                                                         NULL, NULL, NULL, NULL);
+        return runtimeCallInternal<ExceptionStyle::CAPI, NOT_REWRITABLE>(
+            callable_object, NULL, ArgPassSpec(0, 0, true, false), args, NULL, NULL, NULL, NULL);
 }
 
 extern "C" int PyObject_GetBuffer(PyObject* obj, Py_buffer* view, int flags) noexcept {

src/runtime/classobj.cpp

@@ -29,12 +29,17 @@ extern "C" {
 BoxedClass* classobj_cls, *instance_cls;
 }
 
+template <Rewritable rewritable>
+static Box* classLookup(BoxedClassobj* cls, BoxedString* attr, GetattrRewriteArgs* rewrite_args) {
+    if (rewritable == NOT_REWRITABLE) {
+        assert(!rewrite_args);
+        rewrite_args = NULL;
+    }
 
-static Box* classLookup(BoxedClassobj* cls, BoxedString* attr, GetattrRewriteArgs* rewrite_args = NULL) {
     if (rewrite_args)
         assert(!rewrite_args->isSuccessful());
 
-    Box* r = cls->getattr(attr, rewrite_args);
+    Box* r = cls->getattr<rewritable>(attr, rewrite_args);
     if (r) {
         if (rewrite_args)
             rewrite_args->assertReturnConvention(ReturnConvention::HAS_RETURN);
@@ -51,7 +56,7 @@ static Box* classLookup(BoxedClassobj* cls, BoxedString* attr, GetattrRewriteArg
 
     for (auto b : *cls->bases) {
         RELEASE_ASSERT(b->cls == classobj_cls, "");
-        Box* r = classLookup(static_cast<BoxedClassobj*>(b), attr, rewrite_args);
+        Box* r = classLookup<NOT_REWRITABLE>(static_cast<BoxedClassobj*>(b), attr, rewrite_args);
         if (r)
             return r;
     }
@@ -59,6 +64,10 @@ static Box* classLookup(BoxedClassobj* cls, BoxedString* attr, GetattrRewriteArg
     return NULL;
 }
 
+static Box* classLookup(BoxedClassobj* cls, BoxedString* attr) {
+    return classLookup<NOT_REWRITABLE>(cls, attr, NULL);
+}
+
 extern "C" PyObject* _PyInstance_Lookup(PyObject* pinst, PyObject* pname) noexcept {
     RELEASE_ASSERT(PyInstance_Check(pinst), "");
     BoxedInstance* inst = (BoxedInstance*)pinst;
@@ -68,7 +77,7 @@ extern "C" PyObject* _PyInstance_Lookup(PyObject* pinst, PyObject* pname) noexce
 
     try {
         internStringMortalInplace(name);
-        Box* v = inst->getattr(name, NULL);
+        Box* v = inst->getattr(name);
         if (v == NULL)
             v = classLookup(inst->inst_cls, name);
         return v;
@@ -326,9 +335,15 @@ Box* classobjRepr(Box* _obj) {
 }
 
 // Analogous to CPython's instance_getattr2
+template <Rewritable rewritable>
 static Box* instanceGetattributeSimple(BoxedInstance* inst, BoxedString* attr_str,
                                        GetattrRewriteArgs* rewrite_args = NULL) {
-    Box* r = inst->getattr(attr_str, rewrite_args);
+    if (rewritable == NOT_REWRITABLE) {
+        assert(!rewrite_args);
+        rewrite_args = NULL;
+    }
+
+    Box* r = inst->getattr<rewritable>(attr_str, rewrite_args);
     if (r) {
         if (rewrite_args)
             rewrite_args->assertReturnConvention(ReturnConvention::HAS_RETURN);
@@ -350,7 +365,7 @@ static Box* instanceGetattributeSimple(BoxedInstance* inst, BoxedString* attr_st
     }
     GetattrRewriteArgs grewriter_inst_args(rewrite_args ? rewrite_args->rewriter : NULL, r_inst_cls,
                                            rewrite_args ? rewrite_args->rewriter->getReturnDestination() : Location());
-    r = classLookup(inst->inst_cls, attr_str, rewrite_args ? &grewriter_inst_args : NULL);
+    r = classLookup<rewritable>(inst->inst_cls, attr_str, rewrite_args ? &grewriter_inst_args : NULL);
     if (!grewriter_inst_args.isSuccessful())
         rewrite_args = NULL;
 
@@ -371,9 +386,15 @@ static Box* instanceGetattributeSimple(BoxedInstance* inst, BoxedString* attr_st
     return NULL;
 }
 
+template <Rewritable rewritable>
 static Box* instanceGetattributeWithFallback(BoxedInstance* inst, BoxedString* attr_str,
                                              GetattrRewriteArgs* rewrite_args = NULL) {
-    Box* attr_obj = instanceGetattributeSimple(inst, attr_str, rewrite_args);
+    if (rewritable == NOT_REWRITABLE) {
+        assert(!rewrite_args);
+        rewrite_args = NULL;
+    }
+
+    Box* attr_obj = instanceGetattributeSimple<rewritable>(inst, attr_str, rewrite_args);
 
     if (attr_obj) {
         if (rewrite_args && rewrite_args->isSuccessful())
@@ -399,14 +420,21 @@ static Box* instanceGetattributeWithFallback(BoxedInstance* inst, BoxedString* a
 
     if (getattr) {
         getattr = processDescriptor(getattr, inst, inst->inst_cls);
-        return runtimeCallInternal<CXX>(getattr, NULL, ArgPassSpec(1), attr_str, NULL, NULL, NULL, NULL);
+        return runtimeCallInternal<CXX, NOT_REWRITABLE>(getattr, NULL, ArgPassSpec(1), attr_str, NULL, NULL, NULL,
+                                                        NULL);
     }
 
     return NULL;
 }
 
+template <Rewritable rewritable>
 static Box* _instanceGetattribute(Box* _inst, BoxedString* attr_str, bool raise_on_missing,
-                                  GetattrRewriteArgs* rewrite_args = NULL) {
+                                  GetattrRewriteArgs* rewrite_args) {
+    if (rewritable == NOT_REWRITABLE) {
+        assert(!rewrite_args);
+        rewrite_args = NULL;
+    }
+
     RELEASE_ASSERT(_inst->cls == instance_cls, "");
     BoxedInstance* inst = static_cast<BoxedInstance*>(_inst);
 
@@ -419,7 +447,7 @@ static Box* _instanceGetattribute(Box* _inst, BoxedString* attr_str, bool raise_
             return inst->inst_cls;
     }
 
-    Box* attr = instanceGetattributeWithFallback(inst, attr_str, rewrite_args);
+    Box* attr = instanceGetattributeWithFallback<rewritable>(inst, attr_str, rewrite_args);
     if (attr) {
         return attr;
     } else if (!raise_on_missing) {
@@ -429,6 +457,9 @@ static Box* _instanceGetattribute(Box* _inst, BoxedString* attr_str, bool raise_
                        attr_str->data());
     }
 }
+static Box* _instanceGetattribute(Box* _inst, BoxedString* attr_str, bool raise_on_missing) {
+    return _instanceGetattribute<NOT_REWRITABLE>(_inst, attr_str, raise_on_missing, NULL);
+}
 
 // Analogous to CPython's instance_getattr
 Box* instance_getattro(Box* cls, Box* attr) noexcept {
@@ -444,13 +475,13 @@ Box* instanceGetattroInternal(Box* cls, Box* _attr, GetattrRewriteArgs* rewrite_
 
     if (S == CAPI) {
         try {
-            return _instanceGetattribute(cls, attr, true, rewrite_args);
+            return _instanceGetattribute<REWRITABLE>(cls, attr, true, rewrite_args);
         } catch (ExcInfo e) {
             setCAPIException(e);
             return NULL;
         }
     } else {
-        return _instanceGetattribute(cls, attr, true, rewrite_args);
+        return _instanceGetattribute<REWRITABLE>(cls, attr, true, rewrite_args);
     }
 }
 
@@ -1137,7 +1168,7 @@ static void instance_dealloc(Box* _inst) noexcept {
     static BoxedString* del_str = internStringImmortal("__del__");
 
     // TODO: any exceptions here should get caught + printed, instead of causing a std::terminate:
-    Box* func = instanceGetattributeSimple(inst, del_str);
+    Box* func = instanceGetattributeSimple<NOT_REWRITABLE>(inst, del_str, NULL);
     if (func)
         runtimeCall(func, ArgPassSpec(0), NULL, NULL, NULL, NULL, NULL);
 }

src/runtime/complex.cpp

@@ -842,7 +842,8 @@ template <ExceptionStyle S> static Box* try_special_method(Box* self) noexcept(S
 
     static BoxedString* float_str = internStringImmortal("__float__");
     if (PyObject_HasAttr((PyObject*)self, float_str)) {
-        Box* r_f = callattrInternal<S>(self, float_str, CLASS_ONLY, NULL, ArgPassSpec(0), NULL, NULL, NULL, NULL, NULL);
+        Box* r_f = callattrInternal<S, NOT_REWRITABLE>(self, float_str, CLASS_ONLY, NULL, ArgPassSpec(0), NULL, NULL,
+                                                       NULL, NULL, NULL);
         if (!PyFloat_Check(r_f)) {
             if (S == CAPI) {
                 if (!PyErr_Occurred())
@@ -857,8 +858,8 @@ template <ExceptionStyle S> static Box* try_special_method(Box* self) noexcept(S
 
     static BoxedString* complex_str = internStringImmortal("__complex__");
     if (PyObject_HasAttr((PyObject*)self, complex_str)) {
-        Box* r
-            = callattrInternal<S>(self, complex_str, CLASS_OR_INST, NULL, ArgPassSpec(0), NULL, NULL, NULL, NULL, NULL);
+        Box* r = callattrInternal<S, NOT_REWRITABLE>(self, complex_str, CLASS_OR_INST, NULL, ArgPassSpec(0), NULL, NULL,
+                                                     NULL, NULL, NULL);
         if (!r) {
             if (S == CAPI) {
                 if (!PyErr_Occurred())

src/runtime/descr.cpp

@@ -47,7 +47,7 @@ static void propertyDocCopy(BoxedProperty* prop, Box* fget) {
 
     static BoxedString* doc_str = internStringImmortal("__doc__");
     try {
-        get_doc = getattrInternal<ExceptionStyle::CXX>(fget, doc_str, NULL);
+        get_doc = getattrInternal<ExceptionStyle::CXX>(fget, doc_str);
     } catch (ExcInfo e) {
         if (!e.matches(Exception)) {
             throw e;

src/runtime/dict.cpp

@@ -327,12 +327,12 @@ extern "C" PyObject* PyDict_GetItem(PyObject* dict, PyObject* key) noexcept {
         /* preserve the existing exception */
         PyObject* err_type, *err_value, *err_tb;
         PyErr_Fetch(&err_type, &err_value, &err_tb);
-        Box* b = getitemInternal<CAPI>(dict, key, NULL);
+        Box* b = getitemInternal<CAPI>(dict, key);
         /* ignore errors */
         PyErr_Restore(err_type, err_value, err_tb);
         return b;
     } else {
-        Box* b = getitemInternal<CAPI>(dict, key, NULL);
+        Box* b = getitemInternal<CAPI>(dict, key);
         if (b == NULL)
             PyErr_Clear();
         return b;
@@ -691,7 +691,7 @@ Box* dictUpdate(BoxedDict* self, BoxedTuple* args, BoxedDict* kwargs) {
     if (args->size()) {
         Box* arg = args->elts[0];
         static BoxedString* keys_str = internStringImmortal("keys");
-        if (getattrInternal<ExceptionStyle::CXX>(arg, keys_str, NULL)) {
+        if (getattrInternal<ExceptionStyle::CXX>(arg, keys_str)) {
             dictMerge(self, arg);
         } else {
             dictMergeFromSeq2(self, arg);

src/runtime/float.cpp

@@ -794,7 +794,8 @@ template <ExceptionStyle S> static BoxedFloat* _floatNew(Box* a) noexcept(S == C
         return res;
     } else {
         static BoxedString* float_str = internStringImmortal("__float__");
-        Box* r = callattrInternal<S>(a, float_str, CLASS_ONLY, NULL, ArgPassSpec(0), NULL, NULL, NULL, NULL, NULL);
+        Box* r = callattrInternal<S, NOT_REWRITABLE>(a, float_str, CLASS_ONLY, NULL, ArgPassSpec(0), NULL, NULL, NULL,
+                                                     NULL, NULL);
 
         if (!r) {
             if (S == CAPI) {

src/runtime/import.cpp

@@ -381,7 +381,7 @@ static Box* importSub(const std::string& name, BoxedString* full_name, Box* pare
         path_list = NULL;
     } else {
         static BoxedString* path_str = internStringImmortal("__path__");
-        path_list = static_cast<BoxedList*>(getattrInternal<ExceptionStyle::CXX>(parent_module, path_str, NULL));
+        path_list = static_cast<BoxedList*>(getattrInternal<ExceptionStyle::CXX>(parent_module, path_str));
         if (path_list == NULL || path_list->cls != list_cls) {
             return None;
         }
@@ -558,7 +558,7 @@ static void ensureFromlist(Box* module, Box* fromlist, std::string& buf, bool re
     static BoxedString* path_str = internStringImmortal("__path__");
     Box* pathlist = NULL;
     try {
-        pathlist = getattrInternal<ExceptionStyle::CXX>(module, path_str, NULL);
+        pathlist = getattrInternal<ExceptionStyle::CXX>(module, path_str);
     } catch (ExcInfo e) {
         if (!e.matches(AttributeError))
             throw e;
@@ -580,14 +580,14 @@ static void ensureFromlist(Box* module, Box* fromlist, std::string& buf, bool re
                 continue;
 
             static BoxedString* all_str = internStringImmortal("__all__");
-            Box* all = getattrInternal<ExceptionStyle::CXX>(module, all_str, NULL);
+            Box* all = getattrInternal<ExceptionStyle::CXX>(module, all_str);
             if (all) {
                 ensureFromlist(module, all, buf, true);
             }
             continue;
         }
 
-        Box* attr = getattrInternal<ExceptionStyle::CXX>(module, s, NULL);
+        Box* attr = getattrInternal<ExceptionStyle::CXX>(module, s);
         if (attr != NULL)
             continue;
 

src/runtime/list.cpp

@@ -837,7 +837,7 @@ private:
 public:
     PyCmpComparer(Box* cmp) : cmp(cmp) {}
     bool operator()(Box* lhs, Box* rhs) {
-        Box* r = runtimeCallInternal<CXX>(cmp, NULL, ArgPassSpec(2), lhs, rhs, NULL, NULL, NULL);
+        Box* r = runtimeCallInternal<CXX, NOT_REWRITABLE>(cmp, NULL, ArgPassSpec(2), lhs, rhs, NULL, NULL, NULL);
         if (!PyInt_Check(r))
             raiseExcHelper(TypeError, "comparison function must return int, not %.200s", r->cls->tp_name);
         return static_cast<BoxedInt*>(r)->n < 0;
@@ -1141,7 +1141,7 @@ Box* _listCmp(BoxedList* lhs, BoxedList* rhs, AST_TYPE::AST_TYPE op_type) {
         } else if (op_type == AST_TYPE::NotEq) {
             return boxBool(true);
         } else {
-            Box* r = compareInternal(lhs->elts->elts[i], rhs->elts->elts[i], op_type, NULL);
+            Box* r = compareInternal<NOT_REWRITABLE>(lhs->elts->elts[i], rhs->elts->elts[i], op_type, NULL);
             return r;
         }
     }

src/runtime/objmodel.h

@@ -113,22 +113,28 @@ extern "C" Box* getiterHelper(Box* o);
 extern "C" Box* createBoxedIterWrapperIfNeeded(Box* o);
 
 struct SetattrRewriteArgs;
+template <Rewritable rewritable>
 void setattrGeneric(Box* obj, BoxedString* attr, Box* val, SetattrRewriteArgs* rewrite_args);
 
 struct BinopRewriteArgs;
-extern "C" Box* binopInternal(Box* lhs, Box* rhs, int op_type, bool inplace, BinopRewriteArgs* rewrite_args);
+template <Rewritable rewritable>
+Box* binopInternal(Box* lhs, Box* rhs, int op_type, bool inplace, BinopRewriteArgs* rewrite_args);
 
 struct CallRewriteArgs;
-template <ExceptionStyle S>
+template <ExceptionStyle S, Rewritable rewritable>
 Box* runtimeCallInternal(Box* obj, CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Box* arg1, Box* arg2, Box* arg3,
                          Box** args, const std::vector<BoxedString*>* keyword_names) noexcept(S == CAPI);
 
 struct GetitemRewriteArgs;
-template <ExceptionStyle S>
+template <ExceptionStyle S, Rewritable rewritable = REWRITABLE>
 Box* getitemInternal(Box* target, Box* slice, GetitemRewriteArgs* rewrite_args) noexcept(S == CAPI);
+template <ExceptionStyle S> inline Box* getitemInternal(Box* target, Box* slice) noexcept(S == CAPI) {
+    return getitemInternal<S, NOT_REWRITABLE>(target, slice, NULL);
+}
 
 struct LenRewriteArgs;
-template <ExceptionStyle S> BoxedInt* lenInternal(Box* obj, LenRewriteArgs* rewrite_args) noexcept(S == CAPI);
+template <ExceptionStyle S, Rewritable rewritable>
+BoxedInt* lenInternal(Box* obj, LenRewriteArgs* rewrite_args) noexcept(S == CAPI);
 Box* lenCallInternal(BoxedFunctionBase* f, CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Box* arg1, Box* arg2,
                      Box* arg3, Box** args, const std::vector<BoxedString*>* keyword_names);
 
@@ -142,23 +148,27 @@ enum LookupScope {
     CLASS_OR_INST = 3,
 };
 struct CallattrRewriteArgs;
-template <ExceptionStyle S>
+template <ExceptionStyle S, Rewritable rewritable>
 Box* callattrInternal(Box* obj, BoxedString* attr, LookupScope, CallattrRewriteArgs* rewrite_args, ArgPassSpec argspec,
                       Box* arg1, Box* arg2, Box* arg3, Box** args,
                       const std::vector<BoxedString*>* keyword_names) noexcept(S == CAPI);
 extern "C" void delattr_internal(Box* obj, BoxedString* attr, bool allow_custom, DelattrRewriteArgs* rewrite_args);
 struct CompareRewriteArgs;
+template <Rewritable rewritable>
 Box* compareInternal(Box* lhs, Box* rhs, int op_type, CompareRewriteArgs* rewrite_args);
 
 // This is the equivalent of PyObject_GetAttr. Unlike getattrInternalGeneric, it checks for custom __getattr__ or
 // __getattribute__ methods.
-template <ExceptionStyle S>
+template <ExceptionStyle S, Rewritable rewritable = REWRITABLE>
 Box* getattrInternal(Box* obj, BoxedString* attr, GetattrRewriteArgs* rewrite_args) noexcept(S == CAPI);
+template <ExceptionStyle S> inline Box* getattrInternal(Box* obj, BoxedString* attr) noexcept(S == CAPI) {
+    return getattrInternal<S, NOT_REWRITABLE>(obj, attr, NULL);
+}
 
 // This is the equivalent of PyObject_GenericGetAttr, which performs the default lookup rules for getattr() (check for
 // data descriptor, check for instance attribute, check for non-data descriptor). It does not check for __getattr__ or
 // __getattribute__.
-template <bool IsType>
+template <bool IsType, Rewritable rewritable>
 Box* getattrInternalGeneric(Box* obj, BoxedString* attr, GetattrRewriteArgs* rewrite_args, bool cls_only, bool for_call,
                             Box** bind_obj_out, RewriterVar** r_bind_obj_out);
 
@@ -166,7 +176,11 @@ extern "C" PyObject* type_getattro(PyObject* o, PyObject* name) noexcept;
 
 // This is the equivalent of _PyType_Lookup(), which calls Box::getattr() on each item in the object's MRO in the
 // appropriate order. It does not do any descriptor logic.
+template <Rewritable rewritable = REWRITABLE>
 Box* typeLookup(BoxedClass* cls, BoxedString* attr, GetattrRewriteArgs* rewrite_args);
+inline Box* typeLookup(BoxedClass* cls, BoxedString* attr) {
+    return typeLookup<NOT_REWRITABLE>(cls, attr, NULL);
+}
 
 extern "C" void raiseAttributeErrorStr(const char* typeName, llvm::StringRef attr) __attribute__((__noreturn__));
 extern "C" void raiseAttributeError(Box* obj, llvm::StringRef attr) __attribute__((__noreturn__));

src/runtime/super.cpp

@@ -127,7 +127,7 @@ Box* superGetattribute(Box* _s, Box* _attr) {
         }
     }
 
-    Box* r = typeLookup(s->cls, attr, NULL);
+    Box* r = typeLookup(s->cls, attr);
     // TODO implement this
     RELEASE_ASSERT(r, "should call the equivalent of objectGetattr here");
     return processDescriptor(r, s, s->cls);

src/runtime/types.cpp

@@ -770,8 +770,8 @@ static Box* objectNewNoArgs(BoxedClass* cls) noexcept {
 #ifndef NDEBUG
     static BoxedString* new_str = internStringImmortal("__new__");
     static BoxedString* init_str = internStringImmortal("__init__");
-    assert(typeLookup(cls, new_str, NULL) == typeLookup(object_cls, new_str, NULL)
-           && typeLookup(cls, init_str, NULL) != typeLookup(object_cls, init_str, NULL));
+    assert(typeLookup(cls, new_str) == typeLookup(object_cls, new_str)
+           && typeLookup(cls, init_str) != typeLookup(object_cls, init_str));
 #endif
     return new (cls) Box();
 }
@@ -934,7 +934,7 @@ static Box* typeCallInner(CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Bo
             }
         }
     } else {
-        new_attr = typeLookup(cls, new_str, NULL);
+        new_attr = typeLookup(cls, new_str);
         try {
             if (new_attr->cls != function_cls) // optimization
                 new_attr = processDescriptor(new_attr, None, cls);
@@ -982,7 +982,7 @@ static Box* typeCallInner(CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Bo
     static std::vector<Box*> class_making_news;
     if (class_making_news.empty()) {
         for (BoxedClass* allowed_cls : { object_cls, enumerate_cls, xrange_cls, tuple_cls, list_cls, dict_cls }) {
-            auto new_obj = typeLookup(allowed_cls, new_str, NULL);
+            auto new_obj = typeLookup(allowed_cls, new_str);
             gc::registerPermanentRoot(new_obj, /* allow_duplicates= */ true);
             class_making_news.push_back(new_obj);
         }
@@ -1062,7 +1062,7 @@ static Box* typeCallInner(CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Bo
                 }
             }
         } else {
-            init_attr = typeLookup(cls, init_str, NULL);
+            init_attr = typeLookup(cls, init_str);
         }
     }
 
@@ -1112,7 +1112,8 @@ static Box* typeCallInner(CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Bo
             if (new_npassed_args >= 4)
                 srewrite_args.args = rewrite_args->args;
 
-            made = runtimeCallInternal<S>(new_attr, &srewrite_args, new_argspec, cls, arg2, arg3, args, keyword_names);
+            made = runtimeCallInternal<S, REWRITABLE>(new_attr, &srewrite_args, new_argspec, cls, arg2, arg3, args,
+                                                      keyword_names);
             if (!made) {
                 assert(S == CAPI);
 
@@ -1135,7 +1136,8 @@ static Box* typeCallInner(CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Bo
             made = objectNewNoArgs(cls);
             assert(made);
         } else
-            made = runtimeCallInternal<S>(new_attr, NULL, new_argspec, cls, arg2, arg3, args, keyword_names);
+            made = runtimeCallInternal<S, NOT_REWRITABLE>(new_attr, NULL, new_argspec, cls, arg2, arg3, args,
+                                                          keyword_names);
 
         if (!made) {
             assert(S == CAPI);
@@ -1248,8 +1250,8 @@ static Box* typeCallInner(CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Bo
                 srewrite_args.args_guarded = rewrite_args->args_guarded;
                 srewrite_args.func_guarded = true;
 
-                initrtn
-                    = runtimeCallInternal<S>(init_attr, &srewrite_args, argspec, made, arg2, arg3, args, keyword_names);
+                initrtn = runtimeCallInternal<S, REWRITABLE>(init_attr, &srewrite_args, argspec, made, arg2, arg3, args,
+                                                             keyword_names);
 
                 if (!srewrite_args.out_success) {
                     rewrite_args = NULL;
@@ -1258,7 +1260,8 @@ static Box* typeCallInner(CallRewriteArgs* rewrite_args, ArgPassSpec argspec, Bo
                     rewrite_args->rewriter->call(true, (void*)assertInitNone, srewrite_args.out_rtn);
                 }
             } else {
-                initrtn = runtimeCallInternal<S>(init_attr, NULL, argspec, made, arg2, arg3, args, keyword_names);
+                initrtn = runtimeCallInternal<S, NOT_REWRITABLE>(init_attr, NULL, argspec, made, arg2, arg3, args,
+                                                                 keyword_names);
             }
 
             if (!initrtn) {
@@ -1823,7 +1826,8 @@ extern "C" Box* sliceNew(Box* cls, Box* start, Box* stop, Box** args) {
 
 static Box* instancemethodCall(BoxedInstanceMethod* self, Box* args, Box* kwargs) {
     // Not the most effficient, but it works:
-    return runtimeCallInternal<CXX>(self, NULL, ArgPassSpec(0, 0, true, true), args, kwargs, NULL, NULL, NULL);
+    return runtimeCallInternal<CXX, NOT_REWRITABLE>(self, NULL, ArgPassSpec(0, 0, true, true), args, kwargs, NULL, NULL,
+                                                    NULL);
     // TODO add a tpp_call
 }
 
@@ -1872,7 +1876,7 @@ static Box* instancemethodRepr(Box* b) {
     const char* sfuncname = "?", * sklassname = "?";
 
     static BoxedString* name_str = internStringImmortal("__name__");
-    funcname = getattrInternal<CXX>(func, name_str, NULL);
+    funcname = getattrInternal<CXX>(func, name_str);
 
     if (funcname != NULL) {
         if (!PyString_Check(funcname)) {
@@ -1884,7 +1888,7 @@ static Box* instancemethodRepr(Box* b) {
     if (klass == NULL) {
         klassname = NULL;
     } else {
-        klassname = getattrInternal<CXX>(klass, name_str, NULL);
+        klassname = getattrInternal<CXX>(klass, name_str);
         if (klassname != NULL) {
             if (!PyString_Check(klassname)) {
                 klassname = NULL;
@@ -1916,7 +1920,7 @@ Box* instancemethodEq(BoxedInstanceMethod* self, Box* rhs) {
             return boxBool(true);
         } else {
             if (self->obj != NULL && rhs_im->obj != NULL) {
-                return compareInternal(self->obj, rhs_im->obj, AST_TYPE::Eq, NULL);
+                return compareInternal<NOT_REWRITABLE>(self->obj, rhs_im->obj, AST_TYPE::Eq, NULL);
             } else {
                 return boxBool(false);
             }
@@ -2325,8 +2329,8 @@ public:
 
         if (self->isDictBacked()) {
             static BoxedString* setitem_str = internStringImmortal("__setitem__");
-            return callattrInternal<CXX>(self->getDictBacking(), setitem_str, LookupScope::CLASS_ONLY, NULL,
-                                         ArgPassSpec(2), _key, value, NULL, NULL, NULL);
+            return callattrInternal<CXX, NOT_REWRITABLE>(self->getDictBacking(), setitem_str, LookupScope::CLASS_ONLY,
+                                                         NULL, ArgPassSpec(2), _key, value, NULL, NULL, NULL);
         }
 
         assert(_key->cls == str_cls);
@@ -2362,8 +2366,9 @@ public:
 
         if (self->isDictBacked()) {
             static BoxedString* setdefault_str = internStringImmortal("setdefault");
-            return callattrInternal<CXX>(self->getDictBacking(), setdefault_str, LookupScope::CLASS_ONLY, NULL,
-                                         ArgPassSpec(2), _key, value, NULL, NULL, NULL);
+            return callattrInternal<CXX, NOT_REWRITABLE>(self->getDictBacking(), setdefault_str,
+                                                         LookupScope::CLASS_ONLY, NULL, ArgPassSpec(2), _key, value,
+                                                         NULL, NULL, NULL);
         }
 
         assert(_key->cls == str_cls);
@@ -2649,8 +2654,8 @@ public:
 
         if (self->isDictBacked()) {
             static BoxedString* iter_str = internStringImmortal("__iter__");
-            return callattrInternal<CXX>(self->getDictBacking(), iter_str, LookupScope::CLASS_ONLY, NULL,
-                                         ArgPassSpec(0), NULL, NULL, NULL, NULL, NULL);
+            return callattrInternal<CXX, NOT_REWRITABLE>(self->getDictBacking(), iter_str, LookupScope::CLASS_ONLY,
+                                                         NULL, ArgPassSpec(0), NULL, NULL, NULL, NULL, NULL);
         }
 
         return new AttrWrapperIter(self);
@@ -2664,8 +2669,8 @@ public:
         BoxedDict* dict = (BoxedDict*)AttrWrapper::copy(_self);
         assert(dict->cls == dict_cls);
         static BoxedString* eq_str = internStringImmortal("__eq__");
-        return callattrInternal<CXX>(dict, eq_str, LookupScope::CLASS_ONLY, NULL, ArgPassSpec(1), _other, NULL, NULL,
-                                     NULL, NULL);
+        return callattrInternal<CXX, NOT_REWRITABLE>(dict, eq_str, LookupScope::CLASS_ONLY, NULL, ArgPassSpec(1),
+                                                     _other, NULL, NULL, NULL, NULL);
     }
 
     static Box* ne(Box* _self, Box* _other) { return eq(_self, _other) == True ? False : True; }
@@ -2840,7 +2845,7 @@ Box* objectSetattr(Box* obj, Box* attr, Box* value) {
     }
 
     BoxedString* attr_str = static_cast<BoxedString*>(attr);
-    setattrGeneric(obj, attr_str, value, NULL);
+    setattrGeneric<NOT_REWRITABLE>(obj, attr_str, value, NULL);
     return None;
 }