[lto] Do not use recursion in tsubst_arg_types.

[Kazu Hirata <kazu at codesourcery dot com>]

Hi,

Attached is a patch to not to use recursion in tsubst_arg_types.

We would eventually like to use TREE_VEC for TYPE_ARG_TYPES.  The
recursive nature of tsubst_arg_types makes it difficult to convert the
function to support TREE_VEC in TYPE_ARG_TYPES.

The patch removes recursion from the function.  The patch does not
introduce uses of nth_parm_type and its friends for simplicity.

Tested on x86_64-pc-linux-gnu.  OK to apply to the LTO branch?

Kazu Hirata

2006-07-27  Kazu Hirata  <kazu@codesourcery.com>

	* pt.c (tsubst_arg_types): Do not use recursion.

Index: cp/pt.c
===================================================================
*** cp/pt.c	(revision 115760)
--- cp/pt.c	(working copy)
*************** tsubst_arg_types (tree arg_types,
*** 6713,6749 ****
  		  tsubst_flags_t complain,
  		  tree in_decl)
  {
!   tree remaining_arg_types;
!   tree type;
    tree result = NULL_TREE;
  
!   if (!arg_types || arg_types == void_list_node)
!     return arg_types;
  
!   remaining_arg_types = tsubst_arg_types (TREE_CHAIN (arg_types),
! 					  args, complain, in_decl);
!   if (remaining_arg_types == error_mark_node)
!     return error_mark_node;
  
!   type = tsubst (TREE_VALUE (arg_types), args, complain, in_decl);
!   if (type == error_mark_node)
!     return error_mark_node;
!   if (VOID_TYPE_P (type))
!     {
!       if (complain & tf_error)
  	{
! 	  error ("invalid parameter type %qT", type);
! 	  if (in_decl)
! 	    error ("in declaration %q+D", in_decl);
  	}
-       return error_mark_node;
-     }
  
!   /* Do array-to-pointer, function-to-pointer conversion, and ignore
!      top-level qualifiers as required.  */
!   type = TYPE_MAIN_VARIANT (type_decays_to (type));
  
!   result = hash_tree_cons (NULL_TREE, type, remaining_arg_types);
  
    return result;
  }
--- 6713,6752 ----
  		  tsubst_flags_t complain,
  		  tree in_decl)
  {
!   int len = num_parm_types (arg_types);
!   int i;
    tree result = NULL_TREE;
  
!   for (i = len - 1; i >= 0; i--)
!     {
!       tree type = nth_parm_type (arg_types, i);
  
!       if (i == len - 1 && type == void_type_node)
! 	{
! 	  result = void_list_node;
! 	  continue;
! 	}
  
!       type = tsubst (type, args, complain, in_decl);
!       if (type == error_mark_node)
! 	return error_mark_node;
!       if (VOID_TYPE_P (type))
  	{
! 	  if (complain & tf_error)
! 	    {
! 	      error ("invalid parameter type %qT", type);
! 	      if (in_decl)
! 		error ("in declaration %q+D", in_decl);
! 	    }
! 	  return error_mark_node;
  	}
  
!       /* Do array-to-pointer, function-to-pointer conversion, and
! 	 ignore top-level qualifiers as required.  */
!       type = TYPE_MAIN_VARIANT (type_decays_to (type));
  
!       result = hash_tree_cons (NULL_TREE, type, result);
!     }
  
    return result;
  }