/*
 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
 * Copyright (c) 1991-1995 by Xerox Corporation.  All rights reserved.
 * Copyright (c) 1997 by Silicon Graphics.  All rights reserved.
 * Copyright (c) 1999 by Hewlett-Packard Company.  All rights reserved.
 *
 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
 * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
 *
 * Permission is hereby granted to use or copy this program
 * for any purpose,  provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 */

/*
 * This is mostly an internal header file.  Typical clients should
 * not use it.  Clients that define their own object kinds with
 * debugging allocators will probably want to include this, however.
 * No attempt is made to keep the namespace clean.  This should not be
 * included from header files that are frequently included by clients.
 */

#ifndef _DBG_MLC_H
#define _DBG_MLC_H

# include "gc_priv.h"
# ifdef KEEP_BACK_PTRS
#   include "gc_backptr.h"
# endif

# define START_FLAG ((word)0xfedcedcb)
# define END_FLAG ((word)0xbcdecdef)
        /* Stored both one past the end of user object, and one before  */
        /* the end of the object as seen by the allocator.              */

# if defined(KEEP_BACK_PTRS) || defined(PRINT_BLACK_LIST) \
     || defined(MAKE_BACK_GRAPH)
    /* Pointer "source"s that aren't real locations.    */
    /* Used in oh_back_ptr fields and as "source"       */
    /* argument to some marking functions.              */
#       define NOT_MARKED (ptr_t)(0)
#       define MARKED_FOR_FINALIZATION ((ptr_t)(word)2)
            /* Object was marked because it is finalizable.     */
#       define MARKED_FROM_REGISTER ((ptr_t)(word)4)
            /* Object was marked from a register.  Hence the    */
            /* source of the reference doesn't have an address. */
# endif /* KEEP_BACK_PTRS || PRINT_BLACK_LIST */

/* Object header */
typedef struct {
#   if defined(KEEP_BACK_PTRS) || defined(MAKE_BACK_GRAPH)
        /* We potentially keep two different kinds of back      */
        /* pointers.  KEEP_BACK_PTRS stores a single back       */
        /* pointer in each reachable object to allow reporting  */
        /* of why an object was retained.  MAKE_BACK_GRAPH      */
        /* builds a graph containing the inverse of all         */
        /* "points-to" edges including those involving          */
        /* objects that have just become unreachable. This      */
        /* allows detection of growing chains of unreachable    */
        /* objects.  It may be possible to eventually combine   */
        /* both, but for now we keep them separate.  Both       */
        /* kinds of back pointers are hidden using the          */
        /* following macros.  In both cases, the plain version  */
        /* is constrained to have an least significant bit of 1,*/
        /* to allow it to be distinguished from a free list     */
        /* link.  This means the plain version must have an     */
        /* lsb of 0.                                            */
        /* Note that blocks dropped by black-listing will       */
        /* also have the lsb clear once debugging has           */
        /* started.                                             */
        /* We're careful never to overwrite a value with lsb 0. */
#       if ALIGNMENT == 1
          /* Fudge back pointer to be even.  */
#         define HIDE_BACK_PTR(p) GC_HIDE_POINTER(~1 & (GC_word)(p))
#       else
#         define HIDE_BACK_PTR(p) GC_HIDE_POINTER(p)
#       endif

#       ifdef KEEP_BACK_PTRS
          GC_hidden_pointer oh_back_ptr;
#       endif
#       ifdef MAKE_BACK_GRAPH
          GC_hidden_pointer oh_bg_ptr;
#       endif
#       if defined(KEEP_BACK_PTRS) != defined(MAKE_BACK_GRAPH)
          /* Keep double-pointer-sized alignment.       */
          word oh_dummy;
#       endif
#   endif
    const char * oh_string;     /* object descriptor string     */
    word oh_int;                /* object descriptor integers   */
#   ifdef NEED_CALLINFO
      struct callinfo oh_ci[NFRAMES];
#   endif
#   ifndef SHORT_DBG_HDRS
      word oh_sz;                       /* Original malloc arg.         */
      word oh_sf;                       /* start flag */
#   endif /* SHORT_DBG_HDRS */
} oh;
/* The size of the above structure is assumed not to de-align things,   */
/* and to be a multiple of the word length.                             */

#ifdef SHORT_DBG_HDRS
#   define DEBUG_BYTES (sizeof (oh))
#   define UNCOLLECTABLE_DEBUG_BYTES DEBUG_BYTES
#else
    /* Add space for END_FLAG, but use any extra space that was already */
    /* added to catch off-the-end pointers.                             */
    /* For uncollectable objects, the extra byte is not added.          */
#   define UNCOLLECTABLE_DEBUG_BYTES (sizeof (oh) + sizeof (word))
#   define DEBUG_BYTES (UNCOLLECTABLE_DEBUG_BYTES - EXTRA_BYTES)
#endif

/* Round bytes to words without adding extra byte at end.       */
#define SIMPLE_ROUNDED_UP_WORDS(n) BYTES_TO_WORDS((n) + WORDS_TO_BYTES(1) - 1)

/* ADD_CALL_CHAIN stores a (partial) call chain into an object  */
/* header.  It may be called with or without the allocation     */
/* lock.                                                        */
/* PRINT_CALL_CHAIN prints the call chain stored in an object   */
/* to stderr.  It requires that we do not hold the lock.        */
#if defined(SAVE_CALL_CHAIN)
    struct callinfo;
    GC_INNER void GC_save_callers(struct callinfo info[NFRAMES]);
    GC_INNER void GC_print_callers(struct callinfo info[NFRAMES]);
#   define ADD_CALL_CHAIN(base, ra) GC_save_callers(((oh *)(base)) -> oh_ci)
#   define PRINT_CALL_CHAIN(base) GC_print_callers(((oh *)(base)) -> oh_ci)
#elif defined(GC_ADD_CALLER)
    struct callinfo;
    GC_INNER void GC_print_callers(struct callinfo info[NFRAMES]);
#   define ADD_CALL_CHAIN(base, ra) ((oh *)(base)) -> oh_ci[0].ci_pc = (ra)
#   define PRINT_CALL_CHAIN(base) GC_print_callers(((oh *)(base)) -> oh_ci)
#else
#   define ADD_CALL_CHAIN(base, ra)
#   define PRINT_CALL_CHAIN(base)
#endif

# ifdef GC_ADD_CALLER
#   define OPT_RA ra,
# else
#   define OPT_RA
# endif


/* Check whether object with base pointer p has debugging info  */
/* p is assumed to point to a legitimate object in our part     */
/* of the heap.                                                 */
#ifdef SHORT_DBG_HDRS
# define GC_has_other_debug_info(p) TRUE
#else
  GC_INNER GC_bool GC_has_other_debug_info(ptr_t p);
#endif

#if defined(KEEP_BACK_PTRS) || defined(MAKE_BACK_GRAPH)
# define GC_HAS_DEBUG_INFO(p) \
        ((*((word *)p) & 1) && GC_has_other_debug_info(p))
#else
# define GC_HAS_DEBUG_INFO(p) GC_has_other_debug_info(p)
#endif

/* Store debugging info into p.  Return displaced pointer. */
/* Assumes we don't hold allocation lock.                  */
GC_INNER ptr_t GC_store_debug_info(ptr_t p, word sz, const char *str,
                                   word integer);

#endif /* _DBG_MLC_H */
