Ok, gc is clearing most things now

from_cpython/Include/Python.h

@@ -119,6 +119,8 @@ PyAPI_FUNC(void) PyType_GiveHcAttrsDictDescr(PyTypeObject*) PYSTON_NOEXCEPT;
 PyAPI_FUNC(PyObject*) PyObject_GetHcAttrString(PyObject*, const char*) PYSTON_NOEXCEPT;
 PyAPI_FUNC(int) PyObject_SetHcAttrString(PyObject*, const char*, PyObject*) PYSTON_NOEXCEPT;
 PyAPI_FUNC(int) PyObject_DelHcAttrString(PyObject*, const char*) PYSTON_NOEXCEPT;
+PyAPI_FUNC(int) PyObject_ClearHcAttrs(PyHcAttrs*) PYSTON_NOEXCEPT;
+PyAPI_FUNC(int) PyObject_TraverseHcAttrs(PyHcAttrs*, visitproc visit, void* arg) PYSTON_NOEXCEPT;
 
 // Workaround: call this instead of setting tp_dict.
 PyAPI_FUNC(void) PyType_SetDict(PyTypeObject*, PyObject*) PYSTON_NOEXCEPT;
@@ -128,6 +130,10 @@ PyAPI_FUNC(void) PyType_SetDict(PyTypeObject*, PyObject*) PYSTON_NOEXCEPT;
 // PyType_Ready calls this automatically.
 PyAPI_FUNC(void) PyGC_RegisterStaticConstant(PyObject*) PYSTON_NOEXCEPT;
 
+// Pyston addition:
+PyAPI_FUNC(void) PyGC_Enable() PYSTON_NOEXCEPT;
+PyAPI_FUNC(void) PyGC_Disable() PYSTON_NOEXCEPT;
+
 #include "codecs.h"
 #include "pyerrors.h"
 

from_cpython/Objects/exceptions.c

@@ -117,6 +117,7 @@ BaseException_clear(PyBaseExceptionObject *self)
 {
     // Pyston change:
     // Py_CLEAR(self->dict);
+    PyObject_ClearHcAttrs(&self->hcattrs);
     Py_CLEAR(self->args);
     Py_CLEAR(self->message);
     return 0;
@@ -135,6 +136,9 @@ BaseException_traverse(PyBaseExceptionObject *self, visitproc visit, void *arg)
 {
     // Pyston change:
     // Py_VISIT(self->dict);
+    int vret = PyObject_TraverseHcAttrs(&self->hcattrs, visit, arg);
+    if (vret)
+        return vret;
     Py_VISIT(self->args);
     Py_VISIT(self->message);
     return 0;

src/core/types.h

@@ -592,6 +592,7 @@ public:
     HCAttrs(HiddenClass* hcls = root_hcls) : hcls(hcls), attr_list(nullptr) {}
 
     int traverse(visitproc visit, void* arg) noexcept;
+    void clear() noexcept;
 };
 static_assert(sizeof(HCAttrs) == sizeof(struct _hcattrs), "");
 

src/runtime/types.cpp

@@ -3085,10 +3085,12 @@ extern "C" void PyObject_InitHcAttrs(HCAttrs* attrs) noexcept {
 extern "C" PyObject* PyObject_GetHcAttrString(PyObject* obj, const char* attr) PYSTON_NOEXCEPT {
     return obj->getattr(internStringMortal(attr));
 }
+
 extern "C" int PyObject_SetHcAttrString(PyObject* obj, const char* attr, PyObject* val) PYSTON_NOEXCEPT {
     obj->setattr(internStringMortal(attr), val, NULL);
     return 0;
 }
+
 extern "C" int PyObject_DelHcAttrString(PyObject* obj, const char* attr) PYSTON_NOEXCEPT {
     BoxedString* attr_str = internStringMortal(attr);
     bool has = obj->hasattr(attr_str);
@@ -3098,6 +3100,15 @@ extern "C" int PyObject_DelHcAttrString(PyObject* obj, const char* attr) PYSTON_
     return 0;
 }
 
+extern "C" int PyObject_ClearHcAttrs(HCAttrs* attrs) noexcept {
+    attrs->clear();
+    return 0;
+}
+
+extern "C" int PyObject_TraverseHcAttrs(HCAttrs* attrs, visitproc visit, void* arg) noexcept {
+    return attrs->traverse(visit, arg);
+}
+
 extern "C" PyVarObject* PyObject_InitVar(PyVarObject* op, PyTypeObject* tp, Py_ssize_t size) noexcept {
     assert(op);
     assert(tp);
@@ -3320,20 +3331,7 @@ static Box* getsetDelete(Box* self, Box* obj) {
 void Box::clearAttrs() {
     if (cls->instancesHaveHCAttrs()) {
         HCAttrs* attrs = getHCAttrsPtr();
-        HiddenClass* hcls = attrs->hcls;
-
-        if (unlikely(hcls->type == HiddenClass::DICT_BACKED)) {
-            Box* d = attrs->attr_list->attrs[0];
-            Py_DECREF(d);
-            return;
-        }
-
-        assert(hcls->type == HiddenClass::NORMAL || hcls->type == HiddenClass::SINGLETON);
-
-        for (int i = 0; i < hcls->attributeArraySize(); i++) {
-            Py_DECREF(attrs->attr_list->attrs[i]);
-        }
-        new ((void*)attrs) HCAttrs(root_hcls);
+        attrs->clear();
         return;
     }
 
@@ -3344,6 +3342,23 @@ void Box::clearAttrs() {
     }
 }
 
+void HCAttrs::clear() noexcept {
+    HiddenClass* hcls = this->hcls;
+
+    if (unlikely(hcls->type == HiddenClass::DICT_BACKED)) {
+        Box* d = this->attr_list->attrs[0];
+        Py_DECREF(d);
+        return;
+    }
+
+    assert(hcls->type == HiddenClass::NORMAL || hcls->type == HiddenClass::SINGLETON);
+
+    for (int i = 0; i < hcls->attributeArraySize(); i++) {
+        Py_DECREF(this->attr_list->attrs[i]);
+    }
+    new ((void*)this) HCAttrs(root_hcls);
+}
+
 static void tupledealloc(PyTupleObject* op) noexcept {
     Py_ssize_t i;
     Py_ssize_t len = Py_SIZE(op);
@@ -4127,7 +4142,9 @@ void setupRuntime() {
     for (auto b : classes) {
         Py_DECREF(b);
     }
-    PyGC_Collect();
+    // May need to run multiple collections to collect everything:
+    while (PyGC_Collect())
+        ;
     PRINT_TOTAL_REFS();
     exit(0);
     // XXX