remove gc

1 files changed, 0 insertions, 730 deletions

diff --git a/gc/irix_threads.c b/gc/irix_threads.c
deleted file mode 100644
index 48173e4..0000000
--- a/gc/irix_threads.c
+++ /dev/null
@@ -1,730 +0,0 @@
-/* 
- * Copyright (c) 1991-1995 by Xerox Corporation.  All rights reserved.
- * Copyright (c) 1996-1999 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.
- */
-/*
- * Support code for Irix (>=6.2) Pthreads.  This relies on properties
- * not guaranteed by the Pthread standard.  It may or may not be portable
- * to other implementations.
- *
- * This now also includes an initial attempt at thread support for
- * HP/UX 11.
- *
- * Note that there is a lot of code duplication between linux_threads.c
- * and irix_threads.c; any changes made here may need to be reflected
- * there too.
- */
-
-# if defined(GC_IRIX_THREADS)
-
-# include "private/gc_priv.h"
-# include <pthread.h>
-# include <semaphore.h>
-# include <time.h>
-# include <errno.h>
-# include <unistd.h>
-# include <sys/mman.h>
-# include <sys/time.h>
-
-#undef pthread_create
-#undef pthread_sigmask
-#undef pthread_join
-#undef pthread_detach
-
-#ifdef HANDLE_FORK
-  --> Not yet supported.  Try porting the code from linux_threads.c.
-#endif
-
-void GC_thr_init();
-
-#if 0
-void GC_print_sig_mask()
-{
-    sigset_t blocked;
-    int i;
-
-    if (pthread_sigmask(SIG_BLOCK, NULL, &blocked) != 0)
-    	ABORT("pthread_sigmask");
-    GC_printf0("Blocked: ");
-    for (i = 1; i <= MAXSIG; i++) {
-        if (sigismember(&blocked, i)) { GC_printf1("%ld ",(long) i); }
-    }
-    GC_printf0("\n");
-}
-#endif
-
-/* We use the allocation lock to protect thread-related data structures. */
-
-/* The set of all known threads.  We intercept thread creation and 	*/
-/* joins.  We never actually create detached threads.  We allocate all 	*/
-/* new thread stacks ourselves.  These allow us to maintain this	*/
-/* data structure.							*/
-/* Protected by GC_thr_lock.						*/
-/* Some of this should be declared volatile, but that's incosnsistent	*/
-/* with some library routine declarations.  		 		*/
-typedef struct GC_Thread_Rep {
-    struct GC_Thread_Rep * next;  /* More recently allocated threads	*/
-				  /* with a given pthread id come 	*/
-				  /* first.  (All but the first are	*/
-				  /* guaranteed to be dead, but we may  */
-				  /* not yet have registered the join.) */
-    pthread_t id;
-    word stop;
-#	define NOT_STOPPED 0
-#	define PLEASE_STOP 1
-#	define STOPPED 2
-    word flags;
-#	define FINISHED 1   	/* Thread has exited.	*/
-#	define DETACHED 2	/* Thread is intended to be detached.	*/
-#	define CLIENT_OWNS_STACK	4
-				/* Stack was supplied by client.	*/
-    ptr_t stack;
-    ptr_t stack_ptr;  		/* Valid only when stopped. */
-				/* But must be within stack region at	*/
-				/* all times.				*/
-    size_t stack_size;		/* 0 for original thread.	*/
-    void * status;		/* Used only to avoid premature 	*/
-				/* reclamation of any data it might 	*/
-				/* reference.				*/
-} * GC_thread;
-
-GC_thread GC_lookup_thread(pthread_t id);
-
-/*
- * The only way to suspend threads given the pthread interface is to send
- * signals.  Unfortunately, this means we have to reserve
- * a signal, and intercept client calls to change the signal mask.
- * We use SIG_SUSPEND, defined in gc_priv.h.
- */
-
-pthread_mutex_t GC_suspend_lock = PTHREAD_MUTEX_INITIALIZER;
-				/* Number of threads stopped so far	*/
-pthread_cond_t GC_suspend_ack_cv = PTHREAD_COND_INITIALIZER;
-pthread_cond_t GC_continue_cv = PTHREAD_COND_INITIALIZER;
-
-void GC_suspend_handler(int sig)
-{
-    int dummy;
-    GC_thread me;
-    sigset_t all_sigs;
-    sigset_t old_sigs;
-    int i;
-
-    if (sig != SIG_SUSPEND) ABORT("Bad signal in suspend_handler");
-    me = GC_lookup_thread(pthread_self());
-    /* The lookup here is safe, since I'm doing this on behalf  */
-    /* of a thread which holds the allocation lock in order	*/
-    /* to stop the world.  Thus concurrent modification of the	*/
-    /* data structure is impossible.				*/
-    if (PLEASE_STOP != me -> stop) {
-	/* Misdirected signal.	*/
-	pthread_mutex_unlock(&GC_suspend_lock);
-	return;
-    }
-    pthread_mutex_lock(&GC_suspend_lock);
-    me -> stack_ptr = (ptr_t)(&dummy);
-    me -> stop = STOPPED;
-    pthread_cond_signal(&GC_suspend_ack_cv);
-    pthread_cond_wait(&GC_continue_cv, &GC_suspend_lock);
-    pthread_mutex_unlock(&GC_suspend_lock);
-    /* GC_printf1("Continuing 0x%x\n", pthread_self()); */
-}
-
-
-GC_bool GC_thr_initialized = FALSE;
-
-size_t GC_min_stack_sz;
-
-# define N_FREE_LISTS 25
-ptr_t GC_stack_free_lists[N_FREE_LISTS] = { 0 };
-		/* GC_stack_free_lists[i] is free list for stacks of 	*/
-		/* size GC_min_stack_sz*2**i.				*/
-		/* Free lists are linked through first word.		*/
-
-/* Return a stack of size at least *stack_size.  *stack_size is	*/
-/* replaced by the actual stack size.				*/
-/* Caller holds allocation lock.				*/
-ptr_t GC_stack_alloc(size_t * stack_size)
-{
-    register size_t requested_sz = *stack_size;
-    register size_t search_sz = GC_min_stack_sz;
-    register int index = 0;	/* = log2(search_sz/GC_min_stack_sz) */
-    register ptr_t result;
-    
-    while (search_sz < requested_sz) {
-        search_sz *= 2;
-        index++;
-    }
-    if ((result = GC_stack_free_lists[index]) == 0
-        && (result = GC_stack_free_lists[index+1]) != 0) {
-        /* Try next size up. */
-        search_sz *= 2; index++;
-    }
-    if (result != 0) {
-        GC_stack_free_lists[index] = *(ptr_t *)result;
-    } else {
-        result = (ptr_t) GC_scratch_alloc(search_sz + 2*GC_page_size);
-        result = (ptr_t)(((word)result + GC_page_size) & ~(GC_page_size - 1));
-        /* Protect hottest page to detect overflow. */
-#	ifdef STACK_GROWS_UP
-          /* mprotect(result + search_sz, GC_page_size, PROT_NONE); */
-#	else
-          /* mprotect(result, GC_page_size, PROT_NONE); */
-          result += GC_page_size;
-#	endif
-    }
-    *stack_size = search_sz;
-    return(result);
-}
-
-/* Caller holds allocation lock.					*/
-void GC_stack_free(ptr_t stack, size_t size)
-{
-    register int index = 0;
-    register size_t search_sz = GC_min_stack_sz;
-    
-    while (search_sz < size) {
-        search_sz *= 2;
-        index++;
-    }
-    if (search_sz != size) ABORT("Bad stack size");
-    *(ptr_t *)stack = GC_stack_free_lists[index];
-    GC_stack_free_lists[index] = stack;
-}
-
-
-
-# define THREAD_TABLE_SZ 128	/* Must be power of 2	*/
-volatile GC_thread GC_threads[THREAD_TABLE_SZ];
-
-void GC_push_thread_structures GC_PROTO((void))
-{
-    GC_push_all((ptr_t)(GC_threads), (ptr_t)(GC_threads)+sizeof(GC_threads));
-}
-
-/* Add a thread to GC_threads.  We assume it wasn't already there.	*/
-/* Caller holds allocation lock.					*/
-GC_thread GC_new_thread(pthread_t id)
-{
-    int hv = ((word)id) % THREAD_TABLE_SZ;
-    GC_thread result;
-    static struct GC_Thread_Rep first_thread;
-    static GC_bool first_thread_used = FALSE;
-    
-    if (!first_thread_used) {
-    	result = &first_thread;
-    	first_thread_used = TRUE;
-    	/* Dont acquire allocation lock, since we may already hold it. */
-    } else {
-        result = (struct GC_Thread_Rep *)
-        	 GC_INTERNAL_MALLOC(sizeof(struct GC_Thread_Rep), NORMAL);
-    }
-    if (result == 0) return(0);
-    result -> id = id;
-    result -> next = GC_threads[hv];
-    GC_threads[hv] = result;
-    /* result -> flags = 0;     */
-    /* result -> stop = 0;	*/
-    return(result);
-}
-
-/* Delete a thread from GC_threads.  We assume it is there.	*/
-/* (The code intentionally traps if it wasn't.)			*/
-/* Caller holds allocation lock.				*/
-void GC_delete_thread(pthread_t id)
-{
-    int hv = ((word)id) % THREAD_TABLE_SZ;
-    register GC_thread p = GC_threads[hv];
-    register GC_thread prev = 0;
-    
-    while (!pthread_equal(p -> id, id)) {
-        prev = p;
-        p = p -> next;
-    }
-    if (prev == 0) {
-        GC_threads[hv] = p -> next;
-    } else {
-        prev -> next = p -> next;
-    }
-}
-
-/* If a thread has been joined, but we have not yet		*/
-/* been notified, then there may be more than one thread 	*/
-/* in the table with the same pthread id.			*/
-/* This is OK, but we need a way to delete a specific one.	*/
-void GC_delete_gc_thread(pthread_t id, GC_thread gc_id)
-{
-    int hv = ((word)id) % THREAD_TABLE_SZ;
-    register GC_thread p = GC_threads[hv];
-    register GC_thread prev = 0;
-
-    while (p != gc_id) {
-        prev = p;
-        p = p -> next;
-    }
-    if (prev == 0) {
-        GC_threads[hv] = p -> next;
-    } else {
-        prev -> next = p -> next;
-    }
-}
-
-/* Return a GC_thread corresponding to a given thread_t.	*/
-/* Returns 0 if it's not there.					*/
-/* Caller holds  allocation lock or otherwise inhibits 		*/
-/* updates.							*/
-/* If there is more than one thread with the given id we 	*/
-/* return the most recent one.					*/
-GC_thread GC_lookup_thread(pthread_t id)
-{
-    int hv = ((word)id) % THREAD_TABLE_SZ;
-    register GC_thread p = GC_threads[hv];
-    
-    while (p != 0 && !pthread_equal(p -> id, id)) p = p -> next;
-    return(p);
-}
-
-
-/* Caller holds allocation lock.	*/
-void GC_stop_world()
-{
-    pthread_t my_thread = pthread_self();
-    register int i;
-    register GC_thread p;
-    register int result;
-    struct timespec timeout;
-    
-    for (i = 0; i < THREAD_TABLE_SZ; i++) {
-      for (p = GC_threads[i]; p != 0; p = p -> next) {
-        if (p -> id != my_thread) {
-            if (p -> flags & FINISHED) {
-		p -> stop = STOPPED;
-		continue;
-	    }
-	    p -> stop = PLEASE_STOP;
-            result = pthread_kill(p -> id, SIG_SUSPEND);
-	    /* GC_printf1("Sent signal to 0x%x\n", p -> id); */
-	    switch(result) {
-                case ESRCH:
-                    /* Not really there anymore.  Possible? */
-                    p -> stop = STOPPED;
-                    break;
-                case 0:
-                    break;
-                default:
-                    ABORT("pthread_kill failed");
-            }
-        }
-      }
-    }
-    pthread_mutex_lock(&GC_suspend_lock);
-    for (i = 0; i < THREAD_TABLE_SZ; i++) {
-      for (p = GC_threads[i]; p != 0; p = p -> next) {
-        while (p -> id != my_thread && p -> stop != STOPPED) {
-	    clock_gettime(CLOCK_REALTIME, &timeout);
-            timeout.tv_nsec += 50000000; /* 50 msecs */
-            if (timeout.tv_nsec >= 1000000000) {
-                timeout.tv_nsec -= 1000000000;
-                ++timeout.tv_sec;
-            }
-            result = pthread_cond_timedwait(&GC_suspend_ack_cv,
-					    &GC_suspend_lock,
-                                            &timeout);
-            if (result == ETIMEDOUT) {
-                /* Signal was lost or misdirected.  Try again.      */
-                /* Duplicate signals should be benign.              */
-                result = pthread_kill(p -> id, SIG_SUSPEND);
-	    }
-	}
-      }
-    }
-    pthread_mutex_unlock(&GC_suspend_lock);
-    /* GC_printf1("World stopped 0x%x\n", pthread_self()); */
-}
-
-/* Caller holds allocation lock.	*/
-void GC_start_world()
-{
-    GC_thread p;
-    unsigned i;
-
-    /* GC_printf0("World starting\n"); */
-    for (i = 0; i < THREAD_TABLE_SZ; i++) {
-      for (p = GC_threads[i]; p != 0; p = p -> next) {
-	p -> stop = NOT_STOPPED;
-      }
-    }
-    pthread_mutex_lock(&GC_suspend_lock);
-    /* All other threads are at pthread_cond_wait in signal handler.	*/
-    /* Otherwise we couldn't have acquired the lock.			*/
-    pthread_mutex_unlock(&GC_suspend_lock);
-    pthread_cond_broadcast(&GC_continue_cv);
-}
-
-# ifdef MMAP_STACKS
---> not really supported yet.
-int GC_is_thread_stack(ptr_t addr)
-{
-    register int i;
-    register GC_thread p;
-
-    for (i = 0; i < THREAD_TABLE_SZ; i++) {
-      for (p = GC_threads[i]; p != 0; p = p -> next) {
-        if (p -> stack_size != 0) {
-            if (p -> stack <= addr &&
-                addr < p -> stack + p -> stack_size)
-                   return 1;
-       }
-      }
-    }
-    return 0;
-}
-# endif
-
-/* We hold allocation lock.  Should do exactly the right thing if the	*/
-/* world is stopped.  Should not fail if it isn't.			*/
-void GC_push_all_stacks()
-{
-    register int i;
-    register GC_thread p;
-    register ptr_t sp = GC_approx_sp();
-    register ptr_t hot, cold;
-    pthread_t me = pthread_self();
-    
-    if (!GC_thr_initialized) GC_thr_init();
-    /* GC_printf1("Pushing stacks from thread 0x%x\n", me); */
-    for (i = 0; i < THREAD_TABLE_SZ; i++) {
-      for (p = GC_threads[i]; p != 0; p = p -> next) {
-        if (p -> flags & FINISHED) continue;
-        if (pthread_equal(p -> id, me)) {
-	    hot = GC_approx_sp();
-	} else {
-	    hot = p -> stack_ptr;
-	}
-        if (p -> stack_size != 0) {
-#	  ifdef STACK_GROWS_UP
-	    cold = p -> stack;
-#	  else
-            cold = p -> stack + p -> stack_size;
-#	  endif
-        } else {
-            /* The original stack. */
-            cold = GC_stackbottom;
-        }
-#	ifdef STACK_GROWS_UP
-          GC_push_all_stack(cold, hot);
-#	else
-          GC_push_all_stack(hot, cold);
-#	endif
-      }
-    }
-}
-
-
-/* We hold the allocation lock.	*/
-void GC_thr_init()
-{
-    GC_thread t;
-    struct sigaction act;
-
-    if (GC_thr_initialized) return;
-    GC_thr_initialized = TRUE;
-    GC_min_stack_sz = HBLKSIZE;
-    (void) sigaction(SIG_SUSPEND, 0, &act);
-    if (act.sa_handler != SIG_DFL)
-    	ABORT("Previously installed SIG_SUSPEND handler");
-    /* Install handler.	*/
-	act.sa_handler = GC_suspend_handler;
-	act.sa_flags = SA_RESTART;
-	(void) sigemptyset(&act.sa_mask);
-        if (0 != sigaction(SIG_SUSPEND, &act, 0))
-	    ABORT("Failed to install SIG_SUSPEND handler");
-    /* Add the initial thread, so we can stop it.	*/
-      t = GC_new_thread(pthread_self());
-      t -> stack_size = 0;
-      t -> stack_ptr = (ptr_t)(&t);
-      t -> flags = DETACHED;
-}
-
-int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset)
-{
-    sigset_t fudged_set;
-    
-    if (set != NULL && (how == SIG_BLOCK || how == SIG_SETMASK)) {
-        fudged_set = *set;
-        sigdelset(&fudged_set, SIG_SUSPEND);
-        set = &fudged_set;
-    }
-    return(pthread_sigmask(how, set, oset));
-}
-
-struct start_info {
-    void *(*start_routine)(void *);
-    void *arg;
-    word flags;
-    ptr_t stack;
-    size_t stack_size;
-    sem_t registered;   	/* 1 ==> in our thread table, but 	*/
-				/* parent hasn't yet noticed.		*/
-};
-
-void GC_thread_exit_proc(void *arg)
-{
-    GC_thread me;
-
-    LOCK();
-    me = GC_lookup_thread(pthread_self());
-    if (me -> flags & DETACHED) {
-    	GC_delete_thread(pthread_self());
-    } else {
-	me -> flags |= FINISHED;
-    }
-    UNLOCK();
-}
-
-int GC_pthread_join(pthread_t thread, void **retval)
-{
-    int result;
-    GC_thread thread_gc_id;
-    
-    LOCK();
-    thread_gc_id = GC_lookup_thread(thread);
-    /* This is guaranteed to be the intended one, since the thread id	*/
-    /* cant have been recycled by pthreads.				*/
-    UNLOCK();
-    result = pthread_join(thread, retval);
-    /* Some versions of the Irix pthreads library can erroneously 	*/
-    /* return EINTR when the call succeeds.				*/
-	if (EINTR == result) result = 0;
-    if (result == 0) {
-        LOCK();
-        /* Here the pthread thread id may have been recycled. */
-        GC_delete_gc_thread(thread, thread_gc_id);
-        UNLOCK();
-    }
-    return result;
-}
-
-int GC_pthread_detach(pthread_t thread)
-{
-    int result;
-    GC_thread thread_gc_id;
-    
-    LOCK();
-    thread_gc_id = GC_lookup_thread(thread);
-    UNLOCK();
-    result = pthread_detach(thread);
-    if (result == 0) {
-      LOCK();
-      thread_gc_id -> flags |= DETACHED;
-      /* Here the pthread thread id may have been recycled. */
-      if (thread_gc_id -> flags & FINISHED) {
-        GC_delete_gc_thread(thread, thread_gc_id);
-      }
-      UNLOCK();
-    }
-    return result;
-}
-
-void * GC_start_routine(void * arg)
-{
-    struct start_info * si = arg;
-    void * result;
-    GC_thread me;
-    pthread_t my_pthread;
-    void *(*start)(void *);
-    void *start_arg;
-
-    my_pthread = pthread_self();
-    /* If a GC occurs before the thread is registered, that GC will	*/
-    /* ignore this thread.  That's fine, since it will block trying to  */
-    /* acquire the allocation lock, and won't yet hold interesting 	*/
-    /* pointers.							*/
-    LOCK();
-    /* We register the thread here instead of in the parent, so that	*/
-    /* we don't need to hold the allocation lock during pthread_create. */
-    /* Holding the allocation lock there would make REDIRECT_MALLOC	*/
-    /* impossible.  It probably still doesn't work, but we're a little  */
-    /* closer ...							*/
-    /* This unfortunately means that we have to be careful the parent	*/
-    /* doesn't try to do a pthread_join before we're registered.	*/
-    me = GC_new_thread(my_pthread);
-    me -> flags = si -> flags;
-    me -> stack = si -> stack;
-    me -> stack_size = si -> stack_size;
-    me -> stack_ptr = (ptr_t)si -> stack + si -> stack_size - sizeof(word);
-    UNLOCK();
-    start = si -> start_routine;
-    start_arg = si -> arg;
-    sem_post(&(si -> registered));
-    pthread_cleanup_push(GC_thread_exit_proc, 0);
-    result = (*start)(start_arg);
-    me -> status = result;
-    me -> flags |= FINISHED;
-    pthread_cleanup_pop(1);
-	/* This involves acquiring the lock, ensuring that we can't exit */
-	/* while a collection that thinks we're alive is trying to stop  */
-	/* us.								 */
-    return(result);
-}
-
-# define copy_attr(pa_ptr, source) *(pa_ptr) = *(source)
-
-int
-GC_pthread_create(pthread_t *new_thread,
-		  const pthread_attr_t *attr,
-                  void *(*start_routine)(void *), void *arg)
-{
-    int result;
-    GC_thread t;
-    void * stack;
-    size_t stacksize;
-    pthread_attr_t new_attr;
-    int detachstate;
-    word my_flags = 0;
-    struct start_info * si = GC_malloc(sizeof(struct start_info)); 
-	/* This is otherwise saved only in an area mmapped by the thread */
-	/* library, which isn't visible to the collector.		 */
-
-    if (0 == si) return(ENOMEM);
-    if (0 != sem_init(&(si -> registered), 0, 0)) {
-        ABORT("sem_init failed");
-    }
-    si -> start_routine = start_routine;
-    si -> arg = arg;
-    LOCK();
-    if (!GC_is_initialized) GC_init();
-    if (NULL == attr) {
-        stack = 0;
-	(void) pthread_attr_init(&new_attr);
-    } else {
-	copy_attr(&new_attr, attr);
-	pthread_attr_getstackaddr(&new_attr, &stack);
-    }
-    pthread_attr_getstacksize(&new_attr, &stacksize);
-    pthread_attr_getdetachstate(&new_attr, &detachstate);
-    if (stacksize < GC_min_stack_sz) ABORT("Stack too small");
-    if (0 == stack) {
-     	stack = (void *)GC_stack_alloc(&stacksize);
-     	if (0 == stack) {
-     	    UNLOCK();
-     	    return(ENOMEM);
-     	}
-	pthread_attr_setstackaddr(&new_attr, stack);
-    } else {
-    	my_flags |= CLIENT_OWNS_STACK;
-    }
-    if (PTHREAD_CREATE_DETACHED == detachstate) my_flags |= DETACHED;
-    si -> flags = my_flags;
-    si -> stack = stack;
-    si -> stack_size = stacksize;
-    result = pthread_create(new_thread, &new_attr, GC_start_routine, si);
-    if (0 == new_thread && !(my_flags & CLIENT_OWNS_STACK)) {
-      	GC_stack_free(stack, stacksize);
-    }        
-    UNLOCK();  
-    /* Wait until child has been added to the thread table.		*/
-    /* This also ensures that we hold onto si until the child is done	*/
-    /* with it.  Thus it doesn't matter whether it is otherwise		*/
-    /* visible to the collector.					*/
-        while (0 != sem_wait(&(si -> registered))) {
-	  if (errno != EINTR) {
-	    GC_printf1("Sem_wait: errno = %ld\n", (unsigned long) errno);
-	    ABORT("sem_wait failed");
-	  }
-	}
-        sem_destroy(&(si -> registered));
-    pthread_attr_destroy(&new_attr);  /* Probably unnecessary under Irix */
-    return(result);
-}
-
-VOLATILE GC_bool GC_collecting = 0;
-			/* A hint that we're in the collector and       */
-                        /* holding the allocation lock for an           */
-                        /* extended period.                             */
-
-/* Reasonably fast spin locks.  Basically the same implementation */
-/* as STL alloc.h.						  */
-
-#define SLEEP_THRESHOLD 3
-
-unsigned long GC_allocate_lock = 0;
-# define GC_TRY_LOCK() !GC_test_and_set(&GC_allocate_lock)
-# define GC_LOCK_TAKEN GC_allocate_lock
-
-void GC_lock()
-{
-#   define low_spin_max 30  /* spin cycles if we suspect uniprocessor */
-#   define high_spin_max 1000 /* spin cycles for multiprocessor */
-    static unsigned spin_max = low_spin_max;
-    unsigned my_spin_max;
-    static unsigned last_spins = 0;
-    unsigned my_last_spins;
-    volatile unsigned junk;
-#   define PAUSE junk *= junk; junk *= junk; junk *= junk; junk *= junk
-    int i;
-
-    if (GC_TRY_LOCK()) {
-        return;
-    }
-    junk = 0;
-    my_spin_max = spin_max;
-    my_last_spins = last_spins;
-    for (i = 0; i < my_spin_max; i++) {
-        if (GC_collecting) goto yield;
-        if (i < my_last_spins/2 || GC_LOCK_TAKEN) {
-            PAUSE; 
-            continue;
-        }
-        if (GC_TRY_LOCK()) {
-	    /*
-             * got it!
-             * Spinning worked.  Thus we're probably not being scheduled
-             * against the other process with which we were contending.
-             * Thus it makes sense to spin longer the next time.
-	     */
-            last_spins = i;
-            spin_max = high_spin_max;
-            return;
-        }
-    }
-    /* We are probably being scheduled against the other process.  Sleep. */
-    spin_max = low_spin_max;
-yield:
-    for (i = 0;; ++i) {
-        if (GC_TRY_LOCK()) {
-            return;
-        }
-        if (i < SLEEP_THRESHOLD) {
-            sched_yield();
-	} else {
-	    struct timespec ts;
-	
-	    if (i > 26) i = 26;
-			/* Don't wait for more than about 60msecs, even	*/
-			/* under extreme contention.			*/
-	    ts.tv_sec = 0;
-	    ts.tv_nsec = 1 << i;
-	    nanosleep(&ts, 0);
-	}
-    }
-}
-
-# else
-
-#ifndef LINT
-  int GC_no_Irix_threads;
-#endif
-
-# endif /* GC_IRIX_THREADS */
-