1 files changed, 17 insertions, 1 deletions

diff --git a/lstate.h b/lstate.h
index c02b4c8b..697d73b2 100644
--- a/lstate.h
+++ b/lstate.h
@@ -46,6 +46,15 @@
 ** lists. Moreover, barriers can age young objects in young lists as
 ** OLD0, which then become OLD1. However, a list never contains
 ** elements younger than their main ages.
+**
+** The generational collector also uses a pointer 'firstold1', which
+** points to the first OLD1 object in the list. It is used to optimize
+** 'markold'. (Potentially OLD1 objects can be anywhere between 'allgc'
+** and 'reallyold', but often the list has no OLD1 objects or they are
+** after 'old1'.) Note the difference between it and 'old1':
+** 'firstold1': no OLD1 objects before this point; there can be all
+**   ages after it.
+** 'old1': no objects younger than OLD1 after this point.
 */
 
 /*
@@ -54,7 +63,7 @@
 ** can become gray have such a field. The field is not the same
 ** in all objects, but it always has this name.)  Any gray object
 ** must belong to one of these lists, and all objects in these lists
-** must be gray:
+** must be gray (with one exception explained below):
 **
 ** 'gray': regular gray objects, still waiting to be visited.
 ** 'grayagain': objects that must be revisited at the atomic phase.
@@ -65,6 +74,12 @@
 ** 'weak': tables with weak values to be cleared;
 ** 'ephemeron': ephemeron tables with white->white entries;
 ** 'allweak': tables with weak keys and/or weak values to be cleared.
+**
+** The exception to that "gray rule" is the TOUCHED2 objects in
+** generational mode. Those objects stay in a gray list (because they
+** must be visited again at the end of the cycle), but they are marked
+** black (because assignments to them must activate barriers, to move
+** them back to TOUCHED1).
 */
 
 
@@ -266,6 +281,7 @@ typedef struct global_State {
   GCObject *survival;  /* start of objects that survived one GC cycle */
   GCObject *old1;  /* start of old1 objects */
   GCObject *reallyold;  /* objects more than one cycle old ("really old") */
+  GCObject *firstold1;  /* first OLD1 object in the list (if any) */
   GCObject *finobjsur;  /* list of survival objects with finalizers */
   GCObject *finobjold1;  /* list of old1 objects with finalizers */
   GCObject *finobjrold;  /* list of really old objects with finalizers */