* constexpr.c (cxx_eval_indirect_ref): Try folding first.

From-SVN: r223902

gcc/cp/ChangeLog

 2015-05-31  Jason Merrill  <jason@redhat.com>
 
+	* constexpr.c (cxx_eval_indirect_ref): Try folding first.
+
 	PR c++/66320
 	* constexpr.c (cxx_eval_constant_expression): Treat a placeholder
 	with the wrong type as non-constant.

gcc/cp/constexpr.c

@@ -2427,30 +2427,31 @@ cxx_eval_indirect_ref (const constexpr_ctx *ctx, tree t,
 		       bool *non_constant_p, bool *overflow_p)
 {
   tree orig_op0 = TREE_OPERAND (t, 0);
+  bool empty_base = false;
+
+  /* First try to simplify it directly.  */
+  tree r = cxx_fold_indirect_ref (EXPR_LOCATION (t), TREE_TYPE (t), orig_op0,
+				  &empty_base);
+  if (!r)
+    {
+      /* If that didn't work, evaluate the operand first.  */
       tree op0 = cxx_eval_constant_expression (ctx, orig_op0,
 					       /*lval*/false, non_constant_p,
 					       overflow_p);
-  bool empty_base = false;
-  tree r;
-
       /* Don't VERIFY_CONSTANT here.  */
       if (*non_constant_p)
 	return t;
 
       r = cxx_fold_indirect_ref (EXPR_LOCATION (t), TREE_TYPE (t), op0,
 				 &empty_base);
-
-  if (r)
-    r = cxx_eval_constant_expression (ctx, r,
-				      lval, non_constant_p, overflow_p);
-  else
+      if (r == NULL_TREE)
 	{
+	  /* We couldn't fold to a constant value.  Make sure it's not
+	     something we should have been able to fold.  */
 	  tree sub = op0;
 	  STRIP_NOPS (sub);
 	  if (TREE_CODE (sub) == ADDR_EXPR)
 	    {
-	  /* We couldn't fold to a constant value.  Make sure it's not
-	     something we should have been able to fold.  */
 	      gcc_assert (!same_type_ignoring_top_level_qualifiers_p
 			  (TREE_TYPE (TREE_TYPE (sub)), TREE_TYPE (t)));
 	      /* DR 1188 says we don't have to deal with this.  */
@@ -2461,8 +2462,20 @@ cxx_eval_indirect_ref (const constexpr_ctx *ctx, tree t,
 	      *non_constant_p = true;
 	      return t;
 	    }
+
+	  if (lval && op0 != orig_op0)
+	    return build1 (INDIRECT_REF, TREE_TYPE (t), op0);
+	  if (!lval)
+	    VERIFY_CONSTANT (t);
+	  return t;
+	}
     }
 
+  r = cxx_eval_constant_expression (ctx, r,
+				    lval, non_constant_p, overflow_p);
+  if (*non_constant_p)
+    return t;
+
   /* If we're pulling out the value of an empty base, make sure
      that the whole object is constant and then return an empty
      CONSTRUCTOR.  */
@@ -2473,14 +2486,6 @@ cxx_eval_indirect_ref (const constexpr_ctx *ctx, tree t,
       TREE_CONSTANT (r) = true;
     }
 
-  if (r == NULL_TREE)
-    {
-      if (lval && op0 != orig_op0)
-	return build1 (INDIRECT_REF, TREE_TYPE (t), op0);
-      if (!lval)
-	VERIFY_CONSTANT (t);
-      return t;
-    }
   return r;
 }