except.c

gcc-2.95.3 Linux下最常用的C编译器

void
pop_handler (used)
     int used;
{
  action_nesting_level--;
  if (pass == 1)
    {
      struct handler_state *old = current_handler;
      if (old == NULL)
	fatal ("internal error: on stack out of sync");
      current_handler = old->next;

      if (used)
	{ /* Push unto global_handler_list. */
	  old->next = global_handler_list;
	  global_handler_list = old;
	}
      else
	{
	  /* Push onto free_handlers free list. */
	  old->next = free_handlers;
	  free_handlers = old;
	}
    }
  else if (used)
    {
      current_handler = current_handler->next;
    }
}

/* Emit code before an action that has an ON-handler. */

static void
emit_setup_handler ()
{
  tree handler_decl, handler_addr, t;

  /* Field references. */
  tree jbuf_ref, handlers_ref,prev_ref;
  if (!exceptions_initialized)
    {
      /* We temporarily reset the maximum_field_alignment to zero so the
	 compiler's exception data structures can be compatible with the
	 run-time system, even when we're compiling with -fpack. */
      extern int maximum_field_alignment;
      int save_maximum_field_alignment = maximum_field_alignment;
      maximum_field_alignment = 0;
      push_obstacks_nochange ();
      end_temporary_allocation ();
      initialize_exceptions ();
      pop_obstacks ();
      maximum_field_alignment = save_maximum_field_alignment;
    }

  push_momentary ();

  handler_decl = build_lang_decl (VAR_DECL,
				  get_unique_identifier ("handler"),
				  handler_link_type);
  push_obstacks_nochange ();
  pushdecl(handler_decl);
  expand_decl (handler_decl);
  finish_decl (handler_decl);

  jbuf_ref = build_component_ref (handler_decl, jbuf_ident);
  jbuf_ref = build_chill_arrow_expr (jbuf_ref, 1);
  handlers_ref = build_component_ref (handler_decl, handlers_ident);
  prev_ref = build_component_ref (handler_decl, prev_ident);

  /* Emit code to link in handler in __exceptionStack chain. */
  mark_addressable (handler_decl);
  handler_addr = build1 (ADDR_EXPR, handler_link_pointer_type, handler_decl);
  if (inline_exception_stack_ops)
    {
      expand_expr_stmt (build_chill_modify_expr (prev_ref,
						 exception_stack_decl));
      expand_expr_stmt (build_chill_modify_expr (exception_stack_decl,
						 handler_addr));
      current_handler->handler_ref = prev_ref;
    }
  else
    {
      expand_expr_stmt (build_chill_function_call (link_handler_decl,
					     build_tree_list (NULL_TREE,
							      handler_addr)));
      current_handler->handler_ref = handler_addr;
    }

  /* Expand:  handler->__handlers = { <<array mapping names to ints } */
  t =  build1 (NOP_EXPR, build_pointer_type (handler_element_type),
	       build_chill_arrow_expr (start_handler_array (), 1));
  expand_expr_stmt (build_chill_modify_expr (handlers_ref, t));

  /* Emit code to unlink handler. */
  if (inline_exception_stack_ops)
    current_handler->unlink_cleanup
      = build_chill_modify_expr (exception_stack_decl,
				 current_handler->handler_ref);
  else
    current_handler->unlink_cleanup
      = build_chill_function_call (unlink_handler_decl,
				   build_tree_list(NULL_TREE,
					       current_handler->handler_ref));
  cleanup_chain = tree_cons (build_int_2 (action_nesting_level, 0),
			     current_handler->unlink_cleanup,
			     cleanup_chain);

  /* Emit code for setjmp. */
  
  current_handler->setjmp_expr =
    build_chill_function_call (BISJ, build_tree_list (NULL_TREE, jbuf_ref));
  expand_start_case (1, current_handler->setjmp_expr,
		     integer_type_node, "on handler");

  chill_handle_case_label (integer_zero_node, current_handler->setjmp_expr);
}

/* Start emitting code for: <actions> ON <handlers> END.
   Assume we've parsed <actions>, and the setup needed for it. */

void
chill_start_on ()
{
  expand_expr_stmt (current_handler->unlink_cleanup);

  /* Emit code to jump past the handlers. */
  current_handler->end_label = gen_label_rtx ();
  current_handler->compiling = 1;
  emit_jump (current_handler->end_label);
}

void
chill_finish_on ()
{
  expand_end_case (current_handler->setjmp_expr);
  
  finish_handler_array ();

  emit_label (current_handler->end_label);

  pop_momentary ();

  cleanup_chain = TREE_CHAIN (cleanup_chain);
}

void
chill_handle_on_labels (labels)
     tree labels;
{
  int alternative = ++current_handler->prev_on_alternative;
  if (pass == 1)
    {
      tree handler_number = build_int_2 (alternative, 0);
      current_handler->on_alt_list =
	tree_cons (handler_number, labels, current_handler->on_alt_list);
    }
  else
    {
      /* Find handler_number saved in pass 1. */
      tree tmp = current_handler->on_alt_list;
      while (TREE_INT_CST_LOW (TREE_PURPOSE (tmp)) != alternative)
	tmp = TREE_CHAIN (tmp);
      if (expand_exit_needed)
	expand_exit_something (), expand_exit_needed = 0;
      chill_handle_case_label (TREE_PURPOSE (tmp),
			       current_handler->setjmp_expr);
    }
}

void
chill_start_default_handler ()
{
  current_handler->else_handler = ++current_handler->prev_on_alternative;
  if (!ignoring)
    {
      chill_handle_case_default ();
    }
}

void
chill_check_no_handlers ()
{
  if (current_handler != NULL)
    fatal ("internal error: on stack not empty when done");
}

static void
initialize_exceptions ()
{
  tree jmp_buf_type = build_array_type (integer_type_node,
					build_index_type (build_int_2 (_JBLEN_2-1, 0)));
  tree setjmp_fndecl, link_ftype;
  tree parmtypes
    = tree_cons (NULL_TREE, build_pointer_type (jmp_buf_type), void_list_node);

  setjmp_fndecl = builtin_function ("setjmp",
				    build_function_type (integer_type_node,
							 parmtypes),
				    NOT_BUILT_IN,
				    SETJMP_LIBRARY_NAME);
  BISJ = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (setjmp_fndecl)),
		 setjmp_fndecl);
 
  char_pointer_type_for_handler
    = build_pointer_type (build_type_variant (char_type_node, 1, 0));
  handler_element_type =
    build_chill_struct_type (chainon
			     (build_decl (FIELD_DECL,
					  get_identifier("__exceptid"),
					  char_pointer_type_for_handler),
			      build_decl (FIELD_DECL,
					  get_identifier("__handlerno"),
					  integer_type_node)));

  jbuf_ident = get_identifier("__jbuf");
  prev_ident = get_identifier("__prev");
  handlers_ident = get_identifier("__handlers");

  handler_link_type =
    build_chill_struct_type
      (chainon
       (build_decl (FIELD_DECL, prev_ident, ptr_type_node),
	chainon
	(build_decl (FIELD_DECL, handlers_ident,
		     build_pointer_type (handler_element_type)),
	 build_decl (FIELD_DECL, jbuf_ident, jmp_buf_type))));

  handler_link_pointer_type = build_pointer_type (handler_link_type);

  if (inline_exception_stack_ops)
    {
      exception_stack_decl =
	build_lang_decl (VAR_DECL,
			 get_identifier("__exceptionStack"),
			 handler_link_pointer_type);
      TREE_STATIC (exception_stack_decl) = 1;
      TREE_PUBLIC (exception_stack_decl) = 1;
      DECL_EXTERNAL (exception_stack_decl) = 1;
      push_obstacks_nochange ();
      pushdecl(exception_stack_decl);
      make_decl_rtl (exception_stack_decl, NULL_PTR, 1);
      finish_decl (exception_stack_decl);
    }

  link_ftype = build_function_type (void_type_node,
				    tree_cons (NULL_TREE,
					       handler_link_pointer_type,
					       void_list_node));
  link_handler_decl = builtin_function ("__ch_link_handler", link_ftype,
					NOT_BUILT_IN, NULL_PTR);
  unlink_handler_decl = builtin_function ("__ch_unlink_handler", link_ftype,
					  NOT_BUILT_IN, NULL_PTR);

  exceptions_initialized = 1;
}

/* Do the cleanup(s) needed for a GOTO label.
   We only need to do the last of the cleanups. */

void
expand_goto_except_cleanup (label_level)
     int label_level;
{
  tree list = cleanup_chain;
  tree last = NULL_TREE;
  for ( ; list != NULL_TREE; list = TREE_CHAIN (list))
    {
      if (TREE_INT_CST_LOW (TREE_PURPOSE (list)) > label_level)
	last = list;
      else
	break;
    }
  if (last)
    expand_expr_stmt (TREE_VALUE (last));
}

/* Returns true if there is a valid handler for EXCEPT_NAME
   in the current static scope.
   0 ... no handler found
   1 ... local handler available
   2 ... function may propagate this exception
*/

int
is_handled (except_name)
     tree except_name;
{
  tree t;
  struct handler_state *h = current_handler;

  /* if we are are currently compiling this handler
     we have to start at the next level */
  if (h && h->compiling)
    h = h->next;
  while (h != NULL)
    {
      if (h->function != current_function_decl)
	break;
      if (h->else_handler > 0)
	return 1;
      for (t = h->on_alt_list; t != NULL_TREE; t = TREE_CHAIN (t))
	{
	  if (value_member (except_name, TREE_VALUE (t)))
	    return 1;
	}
      h = h->next;
    }

  t = TYPE_RAISES_EXCEPTIONS (TREE_TYPE (current_function_decl));

  if (value_member (except_name, t))
    return 2;
  return 0;
}

/* function generates code to reraise exceptions
   for PROC's propagating exceptions. */

void
chill_reraise_exceptions (exceptions)
     tree exceptions;
{
  tree wrk;

  if (exceptions == NULL_TREE)
    return; /* just in case */

  if (pass == 1)
    {
      for (wrk = exceptions; wrk != NULL_TREE; wrk = TREE_CHAIN (wrk))
	chill_handle_on_labels (build_tree_list (NULL_TREE, TREE_VALUE (wrk)));
    }
  else /* pass == 2 */
    {
      chill_start_on ();
      expand_exit_needed = 0;

      for (wrk = exceptions; wrk != NULL_TREE; wrk = TREE_CHAIN (wrk))
	{
	  chill_handle_on_labels (TREE_VALUE (wrk));
	  /* do a CAUSE exception */
	  expand_expr_stmt (build_cause_exception (TREE_VALUE (wrk), 0));
	  expand_exit_needed = 1;
	}
      chill_finish_on ();
    }
  pop_handler (1);
}