diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c5893c967c7..f23dfa2177a 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2005-08-03  Zdenek Dvorak  <dvorakz@suse.cz>
+
+	PR tree-optimization/23157
+	* tree-scalar-evolution.c (scev_const_prop): Unshare trees
+	before emitting them.
+
 2005-08-03  Volker Reichelt  <reichelt@igpm.rwth-aachen.de>
 
 	PR tree-optimization/19899
diff --git a/gcc/tree-scalar-evolution.c b/gcc/tree-scalar-evolution.c
index 507e3e91947..65348d08402 100644
--- a/gcc/tree-scalar-evolution.c
+++ b/gcc/tree-scalar-evolution.c
@@ -2719,6 +2719,7 @@ scev_const_prop (void)
 	     in loop into account.  */
 	  if (force_expr_to_var_cost (def) >= target_spill_cost)
 	    continue;
+	  def = unshare_expr (def);
 
 	  if (is_gimple_val (def))
 	    stmts = NULL_TREE;