diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ff2e283c057..a4d8d7958d1 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2001-01-16  Richard Henderson  <rth@redhat.com>
+
+	* unroll.c (precondition_loop_p): Fail if no iteration
+	variable found.
+
 2001-01-16  Phil Edwards  <pme@sources.redhat.com>
 
 	* gcc.c:  When -fsyntax-only is given, do not complain about
diff --git a/gcc/unroll.c b/gcc/unroll.c
index 9289595d039..ec0a151f3eb 100644
--- a/gcc/unroll.c
+++ b/gcc/unroll.c
@@ -1381,7 +1381,14 @@ precondition_loop_p (loop, initial_value, final_value, increment, mode)
       return 1;
     }
 
-  if (loop_info->initial_value == 0)
+  if (loop_info->iteration_var == 0)
+    {
+      if (loop_dump_stream)
+	fprintf (loop_dump_stream,
+		 "Preconditioning: Could not find iteration variable.\n");
+      return 0;
+    }
+  else if (loop_info->initial_value == 0)
     {
       if (loop_dump_stream)
 	fprintf (loop_dump_stream,