text: // -*-Mode: C++;-*- // technically C99
  
  // * BeginRiceCopyright *****************************************************
  //
  // $HeadURL$
  // $Id$
  //
  // --------------------------------------------------------------------------
  // Part of HPCToolkit (hpctoolkit.org)
  //
  // Information about sources of support for research and development of
  // HPCToolkit is at 'hpctoolkit.org' and in 'README.Acknowledgments'.
  // --------------------------------------------------------------------------
  //
  // Copyright ((c)) 2002-2019, Rice University
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  // * Redistributions of source code must retain the above copyright
  //   notice, this list of conditions and the following disclaimer.
  //
  // * Redistributions in binary form must reproduce the above copyright
  //   notice, this list of conditions and the following disclaimer in the
  //   documentation and/or other materials provided with the distribution.
  //
  // * Neither the name of Rice University (RICE) nor the names of its
  //   contributors may be used to endorse or promote products derived from
  //   this software without specific prior written permission.
  //
  // This software is provided by RICE and contributors "as is" and any
  // express or implied warranties, including, but not limited to, the
  // implied warranties of merchantability and fitness for a particular
  // purpose are disclaimed. In no event shall RICE or contributors be
  // liable for any direct, indirect, incidental, special, exemplary, or
  // consequential damages (including, but not limited to, procurement of
  // substitute goods or services; loss of use, data, or profits; or
  // business interruption) however caused and on any theory of liability,
  // whether in contract, strict liability, or tort (including negligence
  // or otherwise) arising in any way out of the use of this software, even
  // if advised of the possibility of such damage.
  //
  // ******************************************************* EndRiceCopyright *
  
  #ifndef UNWINR_INFO_H
  #define UNWINR_INFO_H
  
  //************************* System Include Files ****************************
  
  #include <inttypes.h>
  
  //*************************** User Include Files ****************************
  
  #include "binarytree_uwi.h"
  #include <hpcrun/loadmap.h>
  #include "interval_t.h"
  
  //******************************************************************************
  // type
  //******************************************************************************
  
  /**
   * So far, we have used NEVER to indicate regions of the address space
   * where we cannot compute unwind intervals.
   * Regions outside the segments where code is mapped are marked NEVER.
   *
   * Similarly, if we can’t compute function bounds for a segment (i.e., VDSO),
   * we will also create a region marked NEVER.
   * The reason we use NEVER is that we don’t want to continue trying to
   * build function bounds or intervals for a region in the address space
   * where it will never succeed.
   *
   * When we want to enter unwind intervals for a function into the cskiplist,
   * we insert a record into the cskiplist that says
   *
   *  stat: DEFERRED
   *  bounds [lower, upper)
   *
   *    The DEFERRED status means that no unwind intervals are currently available
   *    for the function range and no one is computing them.
   *
   *    In the code below, any thread that comes along and wants the unwind
   *    intervals for a region that is DEFERRED offers to compute them by
   *    executing a compare-and-swap (CAS) to change DEFERRED to FORTHCOMING.
   *    Multiple threads may try at once. Only one CAS will succeed and
   *    the “winner” with the successful CAS will build the intervals.
   *    All other threads that need them will wait until the FORTHCOMING
   *    intervals are computed, added to the skiplist node and published by
   *    marking the node READY.
  */
  
  // Tree status
  typedef enum {
    NEVER, DEFERRED, FORTHCOMING, READY
  } tree_stat_t;
  
  typedef struct unwindr_info_s {
    interval_t interval;
    load_module_t *lm;
    tree_stat_t treestat;
    bitree_uwi_t *btuwi;
  } unwindr_info_t;
  
  
  #endif
  