diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 2fb28b4e60e..31a7c39e405 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -630,8 +630,11 @@ empty_bb_or_one_feeding_into_p (basic_block bb,
       || gimple_has_side_effects (stmt_to_move))
     return false;
 
-  if (gimple_uses_undefined_value_p (stmt_to_move))
-    return false;
+  ssa_op_iter it;
+  tree use;
+  FOR_EACH_SSA_TREE_OPERAND (use, stmt_to_move, it, SSA_OP_USE)
+    if (ssa_name_maybe_undef_p (use))
+      return false;
 
   /* Allow assignments but allow some builtin/internal calls.
      As const calls don't match any of the above, yet they could
@@ -3967,6 +3970,7 @@ pass_phiopt::execute (function *)
   bool cfgchanged = false;
 
   calculate_dominance_info (CDI_DOMINATORS);
+  mark_ssa_maybe_undefs ();
 
   /* Search every basic block for COND_EXPR we may be able to optimize.
 
diff --git a/gcc/tree-ssa.cc b/gcc/tree-ssa.cc
index 607b37e7cf9..ebba02b8449 100644
--- a/gcc/tree-ssa.cc
+++ b/gcc/tree-ssa.cc
@@ -1377,23 +1377,6 @@ ssa_undefined_value_p (tree t, bool partial)
 }
 
 
-/* Return TRUE iff STMT, a gimple statement, references an undefined
-   SSA name.  */
-
-bool
-gimple_uses_undefined_value_p (gimple *stmt)
-{
-  ssa_op_iter iter;
-  tree op;
-
-  FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE)
-    if (ssa_undefined_value_p (op))
-      return true;
-
-  return false;
-}
-
-
 /* Return TRUE iff there are any non-PHI uses of VAR that dominate the
    end of BB.  If we return TRUE and BB is a loop header, then VAR we
    be assumed to be defined within the loop, even if it is marked as
diff --git a/gcc/tree-ssa.h b/gcc/tree-ssa.h
index fa8c8082311..18c279f29d5 100644
--- a/gcc/tree-ssa.h
+++ b/gcc/tree-ssa.h
@@ -54,7 +54,6 @@ extern tree find_released_ssa_name (tree *, int *, void *);
 
 extern bool ssa_defined_default_def_p (tree t);
 extern bool ssa_undefined_value_p (tree, bool = true);
-extern bool gimple_uses_undefined_value_p (gimple *);
 
 
 bool ssa_name_any_use_dominates_bb_p (tree var, basic_block bb);