diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f8ccdae5f00..b2bcff0fbf6 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2002-05-22  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/6643
+	* emit-rtl.c (widen_memory_access): Only call compare_tree_int
+	if DECL_SIZE_UNIT is INTEGER_CST.
+
 2002-05-22  Richard Henderson  <rth@redhat.com>
 
 	* flow.c (life_analysis): Delete broken reg_label check.
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 2e86dff09a4..963946a4ed8 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -2163,6 +2163,7 @@ widen_memory_access (memref, mode, offset)
       /* Similarly for the decl.  */
       else if (DECL_P (expr)
 	       && DECL_SIZE_UNIT (expr)
+	       && TREE_CODE (DECL_SIZE_UNIT (expr)) == INTEGER_CST
 	       && compare_tree_int (DECL_SIZE_UNIT (expr), size) >= 0
 	       && (! memoffset || INTVAL (memoffset) >= 0))
 	break;