[lto] PATCH: add varargs support to DWARF reader

[Sandra Loosemore <sandra at codesourcery dot com>]

This patch cleans up the reading of DWARF information for formal parameters and 
makes it handle functions with varargs.  OK to commit?

-Sandra

2006-09-20  Sandra Loosemore  <sandra@codesourcery.com>

	* gcc/lto/lto.c (lto_varargs_cookie): Define.
	(lto_read_subroutine_type_subprogram_DIE): Robustify collection
	of formal parameters and make it handle varargs.
	(lto_read_unspecified_parameters_DIE): New.
	(lto_read_DIE): Add lto_read_unspecified_parameters_DIE to table.
	* gcc/lto/lto-tree.h (lto_varargs_cookie): Declare.
	* gcc/lto/lto-lang.c (lto_init): Initialize lto_varargs_cookie.

Index: gcc/lto/lto.c
===================================================================
*** gcc/lto/lto.c	(revision 117105)
--- gcc/lto/lto.c	(working copy)
*************** struct DWARF2_CompUnit
*** 161,166 ****
--- 161,172 ----
    unsigned char cu_pointer_size;
  };
  
+ /* Variables */
+ 
+ /* Cookie for DWARF DW_TAG_unspecified_parameters.  All we need is a uniquely
+    identifiable object; it doesn't need to carry any information.  */
+ tree lto_varargs_cookie;
+ 
  /* Forward Declarations */
  
  static hashval_t
*************** lto_read_subroutine_type_subprogram_DIE 
*** 1774,1781 ****
    bool external;
    VEC(tree,heap) *parms;
    unsigned n_parms;
!   unsigned i;
    bool prototyped;
    tree result;
    int inlined = DW_INL_not_inlined;
  
--- 1780,1789 ----
    bool external;
    VEC(tree,heap) *parms;
    unsigned n_parms;
!   unsigned n_children;
!   unsigned i, j;
    bool prototyped;
+   bool varargs_p;
    tree result;
    int inlined = DW_INL_not_inlined;
  
*************** lto_read_subroutine_type_subprogram_DIE 
*** 1857,1873 ****
      sorry ("support for unprototyped functions not yet implemented");
  
    parms = lto_collect_child_DIEs (fd, abbrev, context);
!   n_parms = VEC_length (tree, parms);
!   arg_types = make_tree_vec (n_parms + (prototyped ? 1 : 0));
!   for (i = 0; i < n_parms; ++i)
      {
        tree parm = VEC_index (tree, parms, i);
!       if (TREE_CODE (parm) != PARM_DECL)
! 	lto_file_corrupt_error ((lto_fd *)fd);
!       TREE_VEC_ELT (arg_types, i) = TREE_TYPE (parm);
      }
!   if (prototyped)
!     TREE_VEC_ELT (arg_types, n_parms) = void_type_node;
    VEC_free (tree, heap, parms);
  
    /* Build the function type.  */
--- 1865,1899 ----
      sorry ("support for unprototyped functions not yet implemented");
  
    parms = lto_collect_child_DIEs (fd, abbrev, context);
! 
!   /* Per the DWARF spec, the children can include "other entries used
!      by formal parameter entries, such as types", as well as parameters
!      and a DW_TAG_unspecified_parameters to indicate varargs.  So we need
!      one loop over the children to count the number of actual parameters
!      and another to assemble the parameter type vector.  */
!   n_children = VEC_length (tree, parms);
!   n_parms = 0;
!   varargs_p = !prototyped;
!   for (i = 0; i < n_children; ++i)
      {
        tree parm = VEC_index (tree, parms, i);
!       if (parm == lto_varargs_cookie)
! 	varargs_p = true;
!       else if (TREE_CODE (parm) == PARM_DECL)
! 	n_parms++;
!     }
!   arg_types = make_tree_vec (n_parms + (varargs_p ? 0 : 1));
!   for (i = 0, j = 0; i < n_children; ++i)
!     {
!       tree parm = VEC_index (tree, parms, i);
!       if (TREE_CODE (parm) == PARM_DECL)
! 	{
! 	  TREE_VEC_ELT (arg_types, j) = TREE_TYPE (parm);
! 	  j++;
! 	}
      }
!   if (!varargs_p)
!     TREE_VEC_ELT (arg_types, j) = void_type_node;
    VEC_free (tree, heap, parms);
  
    /* Build the function type.  */
*************** lto_read_subroutine_type_subprogram_DIE 
*** 1927,1932 ****
--- 1953,1972 ----
  }
  
  static tree
+ lto_read_unspecified_parameters_DIE (lto_info_fd *fd,
+ 				     const DWARF2_abbrev *abbrev,
+ 				     lto_context *context)
+ {
+   gcc_assert (abbrev->tag == DW_TAG_unspecified_parameters);
+   LTO_BEGIN_READ_ATTRS ()
+     {
+     }
+   LTO_END_READ_ATTRS ();
+   lto_read_child_DIEs (fd, abbrev, context);
+   return lto_varargs_cookie;
+ }
+ 
+ static tree
  lto_read_pointer_type_DIE (lto_info_fd *fd,
  			   const DWARF2_abbrev *abbrev,
  			   lto_context *context)
*************** lto_read_DIE (lto_info_fd *fd, lto_conte
*** 2206,2212 ****
        lto_read_subroutine_type_subprogram_DIE,
        NULL, /* typedef */
        NULL, /* union_type */
!       NULL, /* unspecified_parameters */
        NULL, /* variant */
        NULL, /* common_block */
        NULL, /* common_inclusion */
--- 2246,2252 ----
        lto_read_subroutine_type_subprogram_DIE,
        NULL, /* typedef */
        NULL, /* union_type */
!       lto_read_unspecified_parameters_DIE,
        NULL, /* variant */
        NULL, /* common_block */
        NULL, /* common_inclusion */
Index: gcc/lto/lto-tree.h
===================================================================
*** gcc/lto/lto-tree.h	(revision 117105)
--- gcc/lto/lto-tree.h	(working copy)
*************** union lang_tree_node GTY(
*** 67,70 ****
--- 67,73 ----
  /* Vector to keep track of external variables we've seen so far.  */
  extern GTY(()) VEC(tree,gc) *lto_global_var_decls;
  
+ /* Cookie for DWARF DW_TAG_unspecified_parameters.  */
+ extern GTY(()) tree lto_varargs_cookie;
+ 
  #endif /* GCC_LTO_TREE_H */
Index: gcc/lto/lto-lang.c
===================================================================
*** gcc/lto/lto-lang.c	(revision 117105)
--- gcc/lto/lto-lang.c	(working copy)
*************** lto_init (void)
*** 161,166 ****
--- 161,167 ----
  
    /* Initialize LTO-specific data structures.  */
    lto_global_var_decls = VEC_alloc (tree, gc, 256);
+   lto_varargs_cookie = tree_cons (NULL_TREE, NULL_TREE, NULL_TREE);
  
    return true;
  }