source: trunk/gcc/boehm-gc/stubborn.c@ 2700

/* 
 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
 * Copyright (c) 1991-1994 by Xerox Corporation.  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.
 */
/* Boehm, July 31, 1995 5:02 pm PDT */


#include "private/gc_priv.h"

# ifdef STUBBORN_ALLOC
/* Stubborn object (hard to change, nearly immutable) allocation. */

extern ptr_t GC_clear_stack();  /* in misc.c, behaves like identity */

#define GENERAL_MALLOC(lb,k) \
    (GC_PTR)GC_clear_stack(GC_generic_malloc((word)lb, k))

/* Data structure representing immutable objects that   */
/* are still being initialized.                         */
/* This is a bit baroque in order to avoid acquiring    */
/* the lock twice for a typical allocation.             */

GC_PTR * GC_changing_list_start;

void GC_push_stubborn_structures GC_PROTO((void))
{
    GC_push_all((ptr_t)(&GC_changing_list_start),
                (ptr_t)(&GC_changing_list_start) + sizeof(GC_PTR *));
}

# ifdef THREADS
  VOLATILE GC_PTR * VOLATILE GC_changing_list_current;
# else
  GC_PTR * GC_changing_list_current;
# endif
        /* Points at last added element.  Also (ab)used for             */
        /* synchronization.  Updates and reads are assumed atomic.      */

GC_PTR * GC_changing_list_limit;
        /* Points at the last word of the buffer, which is always 0     */
        /* All entries in (GC_changing_list_current,                    */
        /* GC_changing_list_limit] are 0                                */


void GC_stubborn_init()
{
#   define INIT_SIZE 10

    GC_changing_list_start = (GC_PTR *)
                        GC_INTERNAL_MALLOC(
                                (word)(INIT_SIZE * sizeof(GC_PTR)),
                                PTRFREE);
    BZERO(GC_changing_list_start,
          INIT_SIZE * sizeof(GC_PTR));
    if (GC_changing_list_start == 0) {
        GC_err_printf0("Insufficient space to start up\n");
        ABORT("GC_stubborn_init: put of space");
    }
    GC_changing_list_current = GC_changing_list_start;
    GC_changing_list_limit = GC_changing_list_start + INIT_SIZE - 1;
    * GC_changing_list_limit = 0;
}