gimplify.c

dummy_object (tree type)
{
  tree t = build_int_cst (build_pointer_type (type), 0);
  return build2 (MEM_REF, type, t, t);
}

/* Gimplify __builtin_va_arg, aka VA_ARG_EXPR, which is not really a
   builtin function, but a very special sort of operator.  */

enum gimplify_status
gimplify_va_arg_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
{
  tree promoted_type, have_va_type;
  tree valist = TREE_OPERAND (*expr_p, 0);
  tree type = TREE_TYPE (*expr_p);
  tree t;
  location_t loc = EXPR_LOCATION (*expr_p);

  /* Verify that valist is of the proper type.  */
  have_va_type = TREE_TYPE (valist);
  if (have_va_type == error_mark_node)
    return GS_ERROR;
  have_va_type = targetm.canonical_va_list_type (have_va_type);

  if (have_va_type == NULL_TREE)
    {
      error_at (loc, "first argument to %<va_arg%> not of type %<va_list%>");
      return GS_ERROR;
    }

  /* Generate a diagnostic for requesting data of a type that cannot
     be passed through `...' due to type promotion at the call site.  */
  if ((promoted_type = lang_hooks.types.type_promotes_to (type))
	   != type)
    {
      static bool gave_help;
      bool warned;

      /* Unfortunately, this is merely undefined, rather than a constraint
	 violation, so we cannot make this an error.  If this call is never
	 executed, the program is still strictly conforming.  */
      warned = warning_at (loc, 0,
	  		   "%qT is promoted to %qT when passed through %<...%>",
			   type, promoted_type);
      if (!gave_help && warned)
	{
	  gave_help = true;
	  inform (loc, "(so you should pass %qT not %qT to %<va_arg%>)",
		  promoted_type, type);
	}

      /* We can, however, treat "undefined" any way we please.
	 Call abort to encourage the user to fix the program.  */
      if (warned)
	inform (loc, "if this code is reached, the program will abort");
      /* Before the abort, allow the evaluation of the va_list
	 expression to exit or longjmp.  */
      gimplify_and_add (valist, pre_p);
      t = build_call_expr_loc (loc,
			       builtin_decl_implicit (BUILT_IN_TRAP), 0);
      gimplify_and_add (t, pre_p);

      /* This is dead code, but go ahead and finish so that the
	 mode of the result comes out right.  */
      *expr_p = dummy_object (type);
      return GS_ALL_DONE;
    }
  else
    {
      /* Make it easier for the backends by protecting the valist argument
	 from multiple evaluations.  */
      if (TREE_CODE (have_va_type) == ARRAY_TYPE)
	{
	  /* For this case, the backends will be expecting a pointer to
	     TREE_TYPE (abi), but it's possible we've
	     actually been given an array (an actual TARGET_FN_ABI_VA_LIST).
	     So fix it.  */
	  if (TREE_CODE (TREE_TYPE (valist)) == ARRAY_TYPE)
	    {
	      tree p1 = build_pointer_type (TREE_TYPE (have_va_type));
	      valist = fold_convert_loc (loc, p1,
					 build_fold_addr_expr_loc (loc, valist));
	    }

	  gimplify_expr (&valist, pre_p, post_p, is_gimple_val, fb_rvalue);
	}
      else
	gimplify_expr (&valist, pre_p, post_p, is_gimple_min_lval, fb_lvalue);

      if (!targetm.gimplify_va_arg_expr)
	/* FIXME: Once most targets are converted we should merely
	   assert this is non-null.  */
	return GS_ALL_DONE;

      *expr_p = targetm.gimplify_va_arg_expr (valist, type, pre_p, post_p);
      return GS_OK;
    }
}

/* Build a new GIMPLE_ASSIGN tuple and append it to the end of *SEQ_P.

   DST/SRC are the destination and source respectively.  You can pass
   ungimplified trees in DST or SRC, in which case they will be
   converted to a gimple operand if necessary.

   This function returns the newly created GIMPLE_ASSIGN tuple.  */

gimple
gimplify_assign (tree dst, tree src, gimple_seq *seq_p)
{
  tree t = build2 (MODIFY_EXPR, TREE_TYPE (dst), dst, src);
  gimplify_and_add (t, seq_p);
  ggc_free (t);
  return gimple_seq_last_stmt (*seq_p);
}

inline hashval_t
gimplify_hasher::hash (const value_type *p)
{
  tree t = p->val;
  return iterative_hash_expr (t, 0);
}

inline bool
gimplify_hasher::equal (const value_type *p1, const compare_type *p2)
{
  tree t1 = p1->val;
  tree t2 = p2->val;
  enum tree_code code = TREE_CODE (t1);

  if (TREE_CODE (t2) != code
      || TREE_TYPE (t1) != TREE_TYPE (t2))
    return false;

  if (!operand_equal_p (t1, t2, 0))
    return false;

#ifdef ENABLE_CHECKING
  /* Only allow them to compare equal if they also hash equal; otherwise
     results are nondeterminate, and we fail bootstrap comparison.  */
  gcc_assert (hash (p1) == hash (p2));
#endif

  return true;
}