stmt.c

早期freebsd实现

	    break;
	  }
      if (n == 0)
	except_stack->exit_label = except_stack->data.except_stmt.after_label;
    }
  if (escapeflag)
    {
      struct nesting *n;
      /* An `escape' from catch clauses goes out to next escape level,
	 if there is one.  Otherwise, it just goes to the end
	 of the construct.  */
      for (n = except_stack->next; n; n = n->next)
	if (n->data.except_stmt.escape_label != 0)
	  {
	    except_stack->data.except_stmt.escape_label
	      = n->data.except_stmt.escape_label;
	    break;
	  }
      if (n == 0)
	except_stack->data.except_stmt.escape_label
	  = except_stack->data.except_stmt.after_label;
    }
  do_pending_stack_adjust ();
  emit_label (except_stack->data.except_stmt.except_label);
}

/* Generate code to `escape' from an exception contour.  This
   is like `exiting', but does not conflict with constructs which
   use `exit_label'.

   Return nonzero if this contour is escapable, otherwise
   return zero, and language-specific code will emit the
   appropriate error message.  */
int
expand_escape_except ()
{
  struct nesting *n;
  last_expr_type = 0;
  for (n = except_stack; n; n = n->next)
    if (n->data.except_stmt.escape_label != 0)
      {
	expand_goto_internal (NULL_TREE,
			      n->data.except_stmt.escape_label, NULL_RTX);
	return 1;
      }

  return 0;
}

/* Finish processing and `except' contour.
   Culls out all exceptions which might be raise but not
   handled, and returns the list to the caller.
   Language-specific code is responsible for dealing with these
   exceptions.  */

tree
expand_end_except ()
{
  struct nesting *n;
  tree raised = NULL_TREE;

  do_pending_stack_adjust ();
  emit_label (except_stack->data.except_stmt.after_label);

  n = except_stack->next;
  if (n)
    {
      /* Propagate exceptions raised but not handled to next
	 highest level.  */
      tree handled = except_stack->data.except_stmt.raised;
      if (handled != void_type_node)
	{
	  tree prev = NULL_TREE;
	  raised = except_stack->data.except_stmt.raised;
	  while (handled)
	    {
	      tree this_raise;
	      for (this_raise = raised, prev = 0; this_raise;
		   this_raise = TREE_CHAIN (this_raise))
		{
		  if (value_member (TREE_VALUE (this_raise), handled))
		    {
		      if (prev)
			TREE_CHAIN (prev) = TREE_CHAIN (this_raise);
		      else
			{
			  raised = TREE_CHAIN (raised);
			  if (raised == NULL_TREE)
			    goto nada;
			}
		    }
		  else
		    prev = this_raise;
		}
	      handled = TREE_CHAIN (handled);
	    }
	  if (prev == NULL_TREE)
	    prev = raised;
	  if (prev)
	    TREE_CHAIN (prev) = n->data.except_stmt.raised;
	nada:
	  n->data.except_stmt.raised = raised;
	}
    }

  POPSTACK (except_stack);
  last_expr_type = 0;
  return raised;
}

/* Record that exception EX is caught by this exception handler.
   Return nonzero if in exception handling construct, otherwise return 0.  */
int
expand_catch (ex)
     tree ex;
{
  tree *raises_ptr;

  if (except_stack == 0)
    return 0;
  raises_ptr = &except_stack->data.except_stmt.handled;
  if (*raises_ptr != void_type_node
      && ex != NULL_TREE
      && ! value_member (ex, *raises_ptr))
    *raises_ptr = tree_cons (NULL_TREE, ex, *raises_ptr);
  return 1;
}

/* Record that this exception handler catches all exceptions.
   Return nonzero if in exception handling construct, otherwise return 0.  */

int
expand_catch_default ()
{
  if (except_stack == 0)
    return 0;
  except_stack->data.except_stmt.handled = void_type_node;
  return 1;
}

int
expand_end_catch ()
{
  if (except_stack == 0 || except_stack->data.except_stmt.after_label == 0)
    return 0;
  expand_goto_internal (NULL_TREE, except_stack->data.except_stmt.after_label,
			NULL_RTX);
  return 1;
}

/* Generate RTL for the start of an if-then.  COND is the expression
   whose truth should be tested.

   If EXITFLAG is nonzero, this conditional is visible to
   `exit_something'.  */

void
expand_start_cond (cond, exitflag)
     tree cond;
     int exitflag;
{
  struct nesting *thiscond = ALLOC_NESTING ();

  /* Make an entry on cond_stack for the cond we are entering.  */

  thiscond->next = cond_stack;
  thiscond->all = nesting_stack;
  thiscond->depth = ++nesting_depth;
  thiscond->data.cond.next_label = gen_label_rtx ();
  /* Before we encounter an `else', we don't need a separate exit label
     unless there are supposed to be exit statements
     to exit this conditional.  */
  thiscond->exit_label = exitflag ? gen_label_rtx () : 0;
  thiscond->data.cond.endif_label = thiscond->exit_label;
  cond_stack = thiscond;
  nesting_stack = thiscond;

  do_jump (cond, thiscond->data.cond.next_label, NULL_RTX);
}

/* Generate RTL between then-clause and the elseif-clause
   of an if-then-elseif-....  */

void
expand_start_elseif (cond)
     tree cond;
{
  if (cond_stack->data.cond.endif_label == 0)
    cond_stack->data.cond.endif_label = gen_label_rtx ();
  emit_jump (cond_stack->data.cond.endif_label);
  emit_label (cond_stack->data.cond.next_label);
  cond_stack->data.cond.next_label = gen_label_rtx ();
  do_jump (cond, cond_stack->data.cond.next_label, NULL_RTX);
}

/* Generate RTL between the then-clause and the else-clause
   of an if-then-else.  */

void
expand_start_else ()
{
  if (cond_stack->data.cond.endif_label == 0)
    cond_stack->data.cond.endif_label = gen_label_rtx ();
  emit_jump (cond_stack->data.cond.endif_label);
  emit_label (cond_stack->data.cond.next_label);
  cond_stack->data.cond.next_label = 0;  /* No more _else or _elseif calls. */
}

/* Generate RTL for the end of an if-then.
   Pop the record for it off of cond_stack.  */

void
expand_end_cond ()
{
  struct nesting *thiscond = cond_stack;

  do_pending_stack_adjust ();
  if (thiscond->data.cond.next_label)
    emit_label (thiscond->data.cond.next_label);
  if (thiscond->data.cond.endif_label)
    emit_label (thiscond->data.cond.endif_label);

  POPSTACK (cond_stack);
  last_expr_type = 0;
}

/* Generate RTL for the start of a loop.  EXIT_FLAG is nonzero if this
   loop should be exited by `exit_something'.  This is a loop for which
   `expand_continue' will jump to the top of the loop.

   Make an entry on loop_stack to record the labels associated with
   this loop.  */

struct nesting *
expand_start_loop (exit_flag)
     int exit_flag;
{
  register struct nesting *thisloop = ALLOC_NESTING ();

  /* Make an entry on loop_stack for the loop we are entering.  */

  thisloop->next = loop_stack;
  thisloop->all = nesting_stack;
  thisloop->depth = ++nesting_depth;
  thisloop->data.loop.start_label = gen_label_rtx ();
  thisloop->data.loop.end_label = gen_label_rtx ();
  thisloop->data.loop.continue_label = thisloop->data.loop.start_label;
  thisloop->exit_label = exit_flag ? thisloop->data.loop.end_label : 0;
  loop_stack = thisloop;
  nesting_stack = thisloop;

  do_pending_stack_adjust ();
  emit_queue ();
  emit_note (NULL_PTR, NOTE_INSN_LOOP_BEG);
  emit_label (thisloop->data.loop.start_label);

  return thisloop;
}

/* Like expand_start_loop but for a loop where the continuation point
   (for expand_continue_loop) will be specified explicitly.  */

struct nesting *
expand_start_loop_continue_elsewhere (exit_flag)
     int exit_flag;
{
  struct nesting *thisloop = expand_start_loop (exit_flag);
  loop_stack->data.loop.continue_label = gen_label_rtx ();
  return thisloop;
}

/* Specify the continuation point for a loop started with
   expand_start_loop_continue_elsewhere.
   Use this at the point in the code to which a continue statement
   should jump.  */

void
expand_loop_continue_here ()
{
  do_pending_stack_adjust ();
  emit_note (NULL_PTR, NOTE_INSN_LOOP_CONT);
  emit_label (loop_stack->data.loop.continue_label);
}

/* Finish a loop.  Generate a jump back to the top and the loop-exit label.
   Pop the block off of loop_stack.  */

void
expand_end_loop ()
{
  register rtx insn = get_last_insn ();
  register rtx start_label = loop_stack->data.loop.start_label;
  rtx last_test_insn = 0;
  int num_insns = 0;

  /* Mark the continue-point at the top of the loop if none elsewhere.  */
  if (start_label == loop_stack->data.loop.continue_label)
    emit_note_before (NOTE_INSN_LOOP_CONT, start_label);

  do_pending_stack_adjust ();

  /* If optimizing, perhaps reorder the loop.  If the loop
     starts with a conditional exit, roll that to the end
     where it will optimize together with the jump back.

     We look for the last conditional branch to the exit that we encounter
     before hitting 30 insns or a CALL_INSN.  If we see an unconditional
     branch to the exit first, use it.

     We must also stop at NOTE_INSN_BLOCK_BEG and NOTE_INSN_BLOCK_END notes
     because moving them is not valid.  */

  if (optimize
      &&
      ! (GET_CODE (insn) == JUMP_INSN
	 && GET_CODE (PATTERN (insn)) == SET
	 && SET_DEST (PATTERN (insn)) == pc_rtx
	 && GET_CODE (SET_SRC (PATTERN (insn))) == IF_THEN_ELSE))
    {
      /* Scan insns from the top of the loop looking for a qualified
	 conditional exit.  */
      for (insn = NEXT_INSN (loop_stack->data.loop.start_label); insn;
	   insn = NEXT_INSN (insn))
	{
	  if (GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == CODE_LABEL)
	    break;

	  if (GET_CODE (insn) == NOTE
	      && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
		  || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
	    break;

	  if (GET_CODE (insn) == JUMP_INSN || GET_CODE (insn) == INSN)
	    num_insns++;

	  if (last_test_insn && num_insns > 30)
	    break;

	  if (GET_CODE (insn) == JUMP_INSN && GET_CODE (PATTERN (insn)) == SET
	      && SET_DEST (PATTERN (insn)) == pc_rtx
	      && GET_CODE (SET_SRC (PATTERN (insn))) == IF_THEN_ELSE
	      && ((GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == LABEL_REF
		   && (XEXP (XEXP (SET_SRC (PATTERN (insn)), 1), 0)
		       == loop_stack->data.loop.end_label))
		  || (GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 2)) == LABEL_REF
		      && (XEXP (XEXP (SET_SRC (PATTERN (insn)), 2), 0)
			  == loop_stack->data.loop.end_label))))
	    last_test_insn = insn;

	  if (last_test_insn == 0 && GET_CODE (insn) == JUMP_INSN
	      && GET_CODE (PATTERN (insn)) == SET
	      && SET_DEST (PATTERN (insn)) == pc_rtx
	      && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF
	      && (XEXP (SET_SRC (PATTERN (insn)), 0)
		  == loop_stack->data.loop.end_label))
	    /* Include BARRIER.  */
	    last_test_insn = NEXT_INSN (insn);
	}

      if (last_test_insn != 0 && last_test_insn != get_last_insn ())
	{
	  /* We found one.  Move everything from there up
	     to the end of the loop, and add a jump into the loop
	     to jump to there.  */
	  register rtx newstart_label = gen_label_rtx ();
	  register rtx start_move = start_label;

	  /* If the start label is preceded by a NOTE_INSN_LOOP_CONT note,
	     then we want to move this note also.  */
	  if (GET_CODE (PREV_INSN (start_move)) == NOTE
	      && (NOTE_LINE_NUMBER (PREV_INSN (start_move))
		  == NOTE_INSN_LOOP_CONT))
	    start_move = PREV_INSN (start_move);

	  emit_label_after (newstart_label, PREV_INSN (start_move));
	  reorder_insns (start_move, last_test_insn, get_last_insn ());
	  emit_jump_insn_after (gen_jump (start_label),
				PREV_INSN (newstart_label));
	  emit_barrier_after (PREV_INSN (newstart_label));
	  start_label = newstart_label;
	}
    }

  emit_jump (start_label);
  emit_note (NULL_PTR, NOTE_INSN_LOOP_END);
  emit_label (loop_stack->data.loop.end_label);

  POPSTACK (loop_stack);

  last_expr_type = 0;
}

/* Generate a jump to the current loop's continue-point.
   This is usually the top of the loop, but may be specified
   explicitly elsewhere.  If not currently inside a loop,
   return 0 and do nothing; caller will print an error message.  */

int
expand_continue_loop (whichloop)
     struct nesting *whichloop;
{
  last_expr_type = 0;
  if (whichloop == 0)
    whichloop = loop_stack;
  if (whichloop == 0)
    return 0;
  expand_goto_internal (NULL_TREE, whichloop->data.loop.continue_label,
			NULL_RTX);
  return 1;
}

/* Generate a jump to exit the current loop.  If not currently inside a loop,
   return 0 and do nothing; caller will print an error message.