Add comment

From-SVN: r38525

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 29047d7306bb106d0115eb8fd00513d67f278d50..cc18eef4ac9f84dc1e8dffd4c57f1aa3ccba033a 100644 (file)
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -3962,10 +3962,14 @@ lookup_template_class (d1, arglist, in_decl, context, entering_scope)
        if (comp_template_args (TREE_PURPOSE (*tp), arglist))
          {
            found = *tp;
+
+           /* Use the move-to-front heuristic to speed up future
+              searches.  */
            *tp = TREE_CHAIN (*tp);
            TREE_CHAIN (found) 
              = DECL_TEMPLATE_INSTANTIATIONS (template);
            DECL_TEMPLATE_INSTANTIATIONS (template) = found;
+
            return TREE_VALUE (found);
          }