1 files changed, 23 insertions, 1 deletions
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 31ca0e1..b3efa99 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -1126,6 +1126,27 @@ valueize_op (tree op)
   return op;
 }
 
+/* Return the constant value for OP, but signal to not follow SSA
+   edges if the definition may be simulated again.  */
+
+static tree
+valueize_op_1 (tree op)
+{
+  if (TREE_CODE (op) == SSA_NAME)
+    {
+      tree tem = get_constant_value (op);
+      if (tem)
+	return tem;
+      /* If the definition may be simulated again we cannot follow
+         this SSA edge as the SSA propagator does not necessarily
+	 re-visit the use.  */
+      gimple def_stmt = SSA_NAME_DEF_STMT (op);
+      if (prop_simulate_again_p (def_stmt))
+	return NULL_TREE;
+    }
+  return op;
+}
+
 /* CCP specific front-end to the non-destructive constant folding
    routines.
 
@@ -1158,7 +1179,8 @@ ccp_fold (gimple stmt)
 
     case GIMPLE_ASSIGN:
     case GIMPLE_CALL:
-      return gimple_fold_stmt_to_constant_1 (stmt, valueize_op);
+      return gimple_fold_stmt_to_constant_1 (stmt,
+					     valueize_op, valueize_op_1);
 
     default:
       gcc_unreachable ();