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/* Iterator routines for manipulating GENERIC and GIMPLE tree statements.

   Copyright (C) 2003, 2004, 2007, 2008 Free Software Foundation, Inc.

   Contributed by Andrew MacLeod  <amacleod@redhat.com>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 3, or (at your option)

any later version.

GCC is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with GCC; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tree.h"

#include "gimple.h"

#include "tree-iterator.h"

#include "ggc.h"

/* This is a cache of STATEMENT_LIST nodes.  We create and destroy them

   fairly often during gimplification.  */

static GTY ((deletable (""))) tree stmt_list_cache;

tree

alloc_stmt_list (void)

{

  tree list = stmt_list_cache;

  if (list)

    {

      stmt_list_cache = TREE_CHAIN (list);

      gcc_assert (stmt_list_cache != list);

      memset (list, 0, sizeof(struct tree_common));

      TREE_SET_CODE (list, STATEMENT_LIST);

    }

  else

    list = make_node (STATEMENT_LIST);

  TREE_TYPE (list) = void_type_node;

  return list;

}

void

free_stmt_list (tree t)

{

  gcc_assert (!STATEMENT_LIST_HEAD (t));

  gcc_assert (!STATEMENT_LIST_TAIL (t));

  /* If this triggers, it's a sign that the same list is being freed

     twice.  */

  gcc_assert (t != stmt_list_cache || stmt_list_cache == NULL);

  TREE_CHAIN (t) = stmt_list_cache;

  stmt_list_cache = t;

}

/* Links a statement, or a chain of statements, before the current stmt.  */

void

tsi_link_before (tree_stmt_iterator *i, tree t, enum tsi_iterator_update mode)

{

  struct tree_statement_list_node *head, *tail, *cur;

  /* Die on looping.  */

  gcc_assert (t != i->container);

  if (TREE_CODE (t) == STATEMENT_LIST)

    {

      head = STATEMENT_LIST_HEAD (t);

      tail = STATEMENT_LIST_TAIL (t);

      STATEMENT_LIST_HEAD (t) = NULL;

      STATEMENT_LIST_TAIL (t) = NULL;

      free_stmt_list (t);

      /* Empty statement lists need no work.  */

      if (!head || !tail)

        {

          gcc_assert (head == tail);

          return;

        }

    }

  else

    {

      head = GGC_NEW (struct tree_statement_list_node);

      head->prev = NULL;

      head->next = NULL;

      head->stmt = t;

      tail = head;

    }

  TREE_SIDE_EFFECTS (i->container) = 1;

  cur = i->ptr;

  /* Link it into the list.  */

  if (cur)

    {

      head->prev = cur->prev;

      if (head->prev)

        head->prev->next = head;

      else

        STATEMENT_LIST_HEAD (i->container) = head;

      tail->next = cur;

      cur->prev = tail;

    }

  else

    {

      head->prev = STATEMENT_LIST_TAIL (i->container);

      if (head->prev)

       head->prev->next = head;

      else

       STATEMENT_LIST_HEAD (i->container) = head;

      STATEMENT_LIST_TAIL (i->container) = tail;

    }

  /* Update the iterator, if requested.  */

  switch (mode)

    {

    case TSI_NEW_STMT:

    case TSI_CONTINUE_LINKING:

    case TSI_CHAIN_START:

      i->ptr = head;

      break;

    case TSI_CHAIN_END:

      i->ptr = tail;

      break;

    case TSI_SAME_STMT:

      break;

    }

}

/* Links a statement, or a chain of statements, after the current stmt.  */

void

tsi_link_after (tree_stmt_iterator *i, tree t, enum tsi_iterator_update mode)

{

  struct tree_statement_list_node *head, *tail, *cur;

  /* Die on looping.  */

  gcc_assert (t != i->container);

  if (TREE_CODE (t) == STATEMENT_LIST)

    {

      head = STATEMENT_LIST_HEAD (t);

      tail = STATEMENT_LIST_TAIL (t);

      STATEMENT_LIST_HEAD (t) = NULL;

      STATEMENT_LIST_TAIL (t) = NULL;

      free_stmt_list (t);

      /* Empty statement lists need no work.  */

      if (!head || !tail)

        {

          gcc_assert (head == tail);

          return;

        }

    }

  else

    {

      head = GGC_NEW (struct tree_statement_list_node);

      head->prev = NULL;

      head->next = NULL;

      head->stmt = t;

      tail = head;

    }

  TREE_SIDE_EFFECTS (i->container) = 1;

  cur = i->ptr;

  /* Link it into the list.  */

  if (cur)

    {

      tail->next = cur->next;

      if (tail->next)

        tail->next->prev = tail;

      else

        STATEMENT_LIST_TAIL (i->container) = tail;

      head->prev = cur;

      cur->next = head;

    }

  else

    {

      gcc_assert (!STATEMENT_LIST_TAIL (i->container));

      STATEMENT_LIST_HEAD (i->container) = head;

      STATEMENT_LIST_TAIL (i->container) = tail;

    }

  /* Update the iterator, if requested.  */

  switch (mode)

    {

    case TSI_NEW_STMT:

    case TSI_CHAIN_START:

      i->ptr = head;

      break;

    case TSI_CONTINUE_LINKING:

    case TSI_CHAIN_END:

      i->ptr = tail;

      break;

    case TSI_SAME_STMT:

      gcc_assert (cur);

      break;

    }

}

/* Remove a stmt from the tree list.  The iterator is updated to point to

   the next stmt.  */

void

tsi_delink (tree_stmt_iterator *i)

{

  struct tree_statement_list_node *cur, *next, *prev;

  cur = i->ptr;

  next = cur->next;

  prev = cur->prev;

  if (prev)

    prev->next = next;

  else

    STATEMENT_LIST_HEAD (i->container) = next;

  if (next)

    next->prev = prev;

  else

    STATEMENT_LIST_TAIL (i->container) = prev;

  if (!next && !prev)

    TREE_SIDE_EFFECTS (i->container) = 0;

  i->ptr = next;

}

/* Return the first expression in a sequence of COMPOUND_EXPRs,

   or in a STATEMENT_LIST.  */

tree

expr_first (tree expr)

{

  if (expr == NULL_TREE)

    return expr;

  if (TREE_CODE (expr) == STATEMENT_LIST)

    {

      struct tree_statement_list_node *n = STATEMENT_LIST_HEAD (expr);

      return n ? n->stmt : NULL_TREE;

    }

  while (TREE_CODE (expr) == COMPOUND_EXPR)

    expr = TREE_OPERAND (expr, 0);

  return expr;

}

/* Return the last expression in a sequence of COMPOUND_EXPRs,

   or in a STATEMENT_LIST.  */

tree

expr_last (tree expr)

{

  if (expr == NULL_TREE)

    return expr;

  if (TREE_CODE (expr) == STATEMENT_LIST)

    {

      struct tree_statement_list_node *n = STATEMENT_LIST_TAIL (expr);

      return n ? n->stmt : NULL_TREE;

    }

  while (TREE_CODE (expr) == COMPOUND_EXPR)

    expr = TREE_OPERAND (expr, 1);

  return expr;

}

#include "gt-tree-iterator.h"