Faster version of attrwrapper.clear()

src/core/types.h

@@ -500,6 +500,8 @@ public:
     bool nonzeroIC();
     Box* hasnextOrNullIC();
     Box* nextIC();
+
+    friend class AttrWrapper;
 };
 static_assert(offsetof(Box, cls) == offsetof(struct _object, ob_type), "");
 

src/runtime/objmodel.cpp

@@ -536,6 +536,8 @@ HiddenClass* HiddenClass::getOrMakeChild(const std::string& attr) {
 
 HiddenClass* HiddenClass::getAttrwrapperChild() {
     assert(type == NORMAL);
+    assert(attrwrapper_offset == -1);
+
     if (!attrwrapper_child) {
         attrwrapper_child = new HiddenClass(this);
         attrwrapper_child->attrwrapper_offset = this->attributeArraySize();

src/runtime/types.cpp

@@ -1553,12 +1553,12 @@ public:
         HCAttrs* attrs = self->b->getHCAttrsPtr();
         RELEASE_ASSERT(attrs->hcls->type == HiddenClass::NORMAL || attrs->hcls->type == HiddenClass::SINGLETON, "");
 
-        while (true) {
-            const auto& attrMap = attrs->hcls->getStrAttrOffsets();
-            if (attrMap.size() == 0)
-                break;
-            self->b->delattr(attrMap.begin()->first(), NULL);
-        }
+        // Clear the attrs array:
+        new ((void*)attrs) HCAttrs(root_hcls);
+        // Add the existing attrwrapper object (ie self) back as the attrwrapper:
+        self->b->appendNewHCAttr(self, NULL);
+        attrs->hcls = attrs->hcls->getAttrwrapperChild();
+
         return None;
     }
 

test/tests/dict_setting.py

@@ -44,6 +44,8 @@ class C(object):
         return 0
 c = C()
 c.attr = "test"
-c.__dict__.clear()
+d1 = c.__dict__
+d1.clear()
 print hasattr(c, "attr")
 print hasattr(c, "foo")
+print c.__dict__ is d1