linux.conf.au
Toolchain Hackers...

/* Hook used by expand_expr to expand language-specific tree codes.  */

rtx
c_expand_expr (exp, target, tmode, modifier)
     tree exp;
     rtx target;
     enum machine_mode tmode;
     enum expand_modifier modifier;
{
  switch (TREE_CODE (exp))
    {
    case STMT_EXPR:
      {
 	tree rtl_expr;
 	rtx result;

 	/* Since expand_expr_stmt calls free_temp_slots after every
 	   expression statement, we must call push_temp_slots here.
 	   Otherwise, any temporaries in use now would be considered
 	   out-of-scope after the first EXPR_STMT from within the
 	   STMT_EXPR.  */
 	push_temp_slots ();
 	rtl_expr = expand_start_stmt_expr ();
 	expand_stmt (STMT_EXPR_STMT (exp));
 	expand_end_stmt_expr (rtl_expr);
 	result = expand_expr (rtl_expr, target, tmode, modifier);
 	pop_temp_slots ();
 	return result;
      }
      break;