(mark_object): Save last 500 values of objptr.

Check for clobberage of ptr, when marking a vector.

1 files changed, 14 insertions, 1 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 8b8b1d3bd7d..495c702d038 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -1269,6 +1269,10 @@ clear_marks ()
    lives in the last slot in the chain.  We recognize the end
    because it is < (unsigned) STRING_BLOCK_SIZE.  */
 
+#define LAST_MARKED_SIZE 500
+Lisp_Object *last_marked[LAST_MARKED_SIZE];
+int last_marked_index;
+
 static void
 mark_object (objptr)
      Lisp_Object *objptr;
@@ -1284,6 +1288,10 @@ mark_object (objptr)
       && (PNTR_COMPARISON_TYPE) XPNTR (obj) >= (PNTR_COMPARISON_TYPE) pure)
     return;
 
+  last_marked[last_marked_index++] = objptr;
+  if (last_marked_index == LAST_MARKED_SIZE)
+    last_marked_index = 0;
+
 #ifdef SWITCH_ENUM_BUG
   switch ((int) XGCTYPE (obj))
 #else
@@ -1328,12 +1336,17 @@ mark_object (objptr)
       {
         register struct Lisp_Vector *ptr = XVECTOR (obj);
         register int size = ptr->size;
+        struct Lisp_Vector *volatile ptr1 = ptr;
         register int i;
 
         if (size & ARRAY_MARK_FLAG) break;   /* Already marked */
         ptr->size |= ARRAY_MARK_FLAG; /* Else mark it */
         for (i = 0; i < size; i++)     /* and then mark its elements */
-          mark_object (&ptr->contents[i]);
+          {
+            if (ptr != ptr1)
+              abort ();
+            mark_object (&ptr->contents[i]);
+          }
       }
       break;