Subclass cleanup must use exact key match to not call VM during GC sweep

src/kuroko/table.h

@@ -140,6 +140,19 @@ extern int krk_tableGet_fast(KrkTable * table, KrkString * str, KrkValue * value
  */
 extern int krk_tableDelete(KrkTable * table, KrkValue key);
 
+/**
+ * @brief Remove a key from a hash table, with identity lookup.
+ * @memberof KrkTable
+ *
+ * Scans the table 'table' for the key 'key' and, if found, removes
+ * the entry, replacing it with a tombstone value.
+ *
+ * @param table Table to delete from.
+ * @param key   Key to delete.
+ * @return 1 if the value was found and deleted, 0 if it was not present.
+ */
+extern int krk_tableDeleteExact(KrkTable * table, KrkValue key);
+
 /**
  * @brief Internal table scan function.
  * @memberof KrkTable

src/memory.c

@@ -237,7 +237,7 @@ static void freeObject(KrkObj * object) {
 			krk_freeTable(&_class->methods);
 			krk_freeTable(&_class->subclasses);
 			if (_class->base) {
-				krk_tableDelete(&_class->base->subclasses, OBJECT_VAL(object));
+				krk_tableDeleteExact(&_class->base->subclasses, OBJECT_VAL(object));
 			}
 			FREE(KrkClass, object);
 			break;

src/table.c

@@ -82,6 +82,29 @@ KrkTableEntry * krk_findEntry(KrkTableEntry * entries, size_t capacity, KrkValue
 	}
 }
 
+KrkTableEntry * krk_findEntryExact(KrkTableEntry * entries, size_t capacity, KrkValue key) {
+	uint32_t index;
+	if (krk_hashValue(key, &index)) {
+		return NULL;
+	}
+	index &= (capacity-1);
+	KrkTableEntry * tombstone = NULL;
+	for (;;) {
+		KrkTableEntry * entry = &entries[index];
+		if (IS_KWARGS(entry->key)) {
+			if (IS_NONE(entry->value)) {
+				return tombstone != NULL ? tombstone : entry;
+			} else {
+				if (tombstone == entry) return tombstone;
+				if (tombstone == NULL) tombstone = entry;
+			}
+		} else if (krk_valuesSame(entry->key, key)) {
+			return entry;
+		}
+		index = (index + 1) & (capacity-1);
+	}
+}
+
 #ifdef __TINYC__
 int __builtin_clz(unsigned int x) {
 	int i = 31;
@@ -189,6 +212,18 @@ int krk_tableDelete(KrkTable * table, KrkValue key) {
 	return 1;
 }
 
+int krk_tableDeleteExact(KrkTable * table, KrkValue key) {
+	if (table->count == 0) return 0;
+	KrkTableEntry * entry = krk_findEntryExact(table->entries, table->capacity, key);
+	if (!entry || IS_KWARGS(entry->key)) {
+		return 0;
+	}
+	table->count--;
+	entry->key = KWARGS_VAL(0);
+	entry->value = KWARGS_VAL(0);
+	return 1;
+}
+
 KrkString * krk_tableFindString(KrkTable * table, const char * chars, size_t length, uint32_t hash) {
 	if (table->count == 0) return NULL;