Re: C++ PATCH to refer to base members using COMPONENT_REF

[Jason Merrill <jason at redhat dot com>]

A slight cleanup of the previous patch.  Tested x86_64-pc-linux-gnu,
applied to trunk.

2004-05-18  Jason Merrill  <jason@redhat.com>

	* class.c (build_base_path): Tidy a bit.

*** class.c.~1~	2004-05-18 15:17:57.000000000 -0400
--- class.c	2004-05-18 15:23:02.000000000 -0400
*************** build_base_path (enum tree_code code,
*** 255,260 ****
--- 255,261 ----
    int fixed_type_p;
    int want_pointer = TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE;
    bool has_empty = false;
+   bool virtual_access;
  
    if (expr == error_mark_node || binfo == error_mark_node || !binfo)
      return error_mark_node;
*************** build_base_path (enum tree_code code,
*** 296,316 ****
    offset = BINFO_OFFSET (binfo);
    fixed_type_p = resolves_to_fixed_type_p (expr, &nonnull);
  
!   if (want_pointer && !nonnull
!       && (!integer_zerop (offset) || (v_binfo && fixed_type_p <= 0)))
      null_test = error_mark_node;
  
!   if (TREE_SIDE_EFFECTS (expr)
!       && (null_test || (v_binfo && fixed_type_p <= 0)))
      expr = save_expr (expr);
  
    if (null_test)
      null_test = fold (build2 (NE_EXPR, boolean_type_node,
  			      expr, integer_zero_node));
  
    /* If this is a simple base reference, express it as a COMPONENT_REF.  */
!   if (code == PLUS_EXPR
!       && (v_binfo == NULL_TREE || fixed_type_p > 0)
        /* We don't build base fields for empty bases, and they aren't very
  	 interesting to the optimizers anyway.  */
        && !has_empty)
--- 297,320 ----
    offset = BINFO_OFFSET (binfo);
    fixed_type_p = resolves_to_fixed_type_p (expr, &nonnull);
  
!   /* Do we need to look in the vtable for the real offset?  */
!   virtual_access = (v_binfo && fixed_type_p <= 0);
! 
!   /* Do we need to check for a null pointer?  */
!   if (want_pointer && !nonnull && (virtual_access || !integer_zerop (offset)))
      null_test = error_mark_node;
  
!   /* Protect against multiple evaluation if necessary.  */
!   if (TREE_SIDE_EFFECTS (expr) && (null_test || virtual_access))
      expr = save_expr (expr);
  
+   /* Now that we've saved expr, build the real null test.  */
    if (null_test)
      null_test = fold (build2 (NE_EXPR, boolean_type_node,
  			      expr, integer_zero_node));
  
    /* If this is a simple base reference, express it as a COMPONENT_REF.  */
!   if (code == PLUS_EXPR && !virtual_access
        /* We don't build base fields for empty bases, and they aren't very
  	 interesting to the optimizers anyway.  */
        && !has_empty)
*************** build_base_path (enum tree_code code,
*** 323,329 ****
        goto out;
      }
  
!   if (v_binfo && fixed_type_p <= 0)
      {
        /* Going via virtual base V_BINFO.  We need the static offset
           from V_BINFO to BINFO, and the dynamic offset from D_BINFO to
--- 327,333 ----
        goto out;
      }
  
!   if (virtual_access)
      {
        /* Going via virtual base V_BINFO.  We need the static offset
           from V_BINFO to BINFO, and the dynamic offset from D_BINFO to