add documentation for TrackingVRegPtr and delete BST_FunctionDef and BST_ClassDef nodes

src/core/cfg.cpp

@@ -36,6 +36,12 @@
 //#define VERBOSITY(x) 2
 
 namespace pyston {
+// This class helps keeping track of the memory locations of vregs inside the bytecode by storing them as offsets from
+// the start of the bytecode if the address is inside the bytecode otherwise it is just stored as a regular pointer.
+// We can't directly keep track of the locations with normal pointers because during bytecode emission the memory
+// location grows several times which will move around the memory location.
+// TODO: all vreg locations should be inside the bytecode but currently we still emit a few references to outside vregs
+// for the BST_ClassDef and BST_FunctionDef nodes. We should try to remove them.
 class TrackingVRegPtr {
 private:
     union {

src/runtime/types.cpp

@@ -30,6 +30,7 @@
 #include "codegen/ast_interpreter.h"
 #include "codegen/entry.h"
 #include "codegen/unwinding.h"
+#include "core/bst.h"
 #include "core/options.h"
 #include "core/stats.h"
 #include "core/types.h"
@@ -4054,6 +4055,8 @@ void CodeConstants::dealloc() const {
     owned_refs.clear();
     for (auto&& e : funcs_and_classes) {
         Py_DECREF(e.second);
+        assert(e.first->type() == BST_TYPE::FunctionDef || e.first->type() == BST_TYPE::ClassDef);
+        delete[] e.first;
     }
     funcs_and_classes.clear();
 }