Imported version version 6.0alpha7.

	* README, README.Mac, README.OS2, README.QUICK, README.alpha,
	README.amiga, README.debugging, README.dj, README.hp, README.linux,
	README.rs6000, README.sgi, README.solaris2, README.uts,
	README.win32, SCoptions.amiga, backptr.h, barrett_diagram,
	dbg_mlc.h, gc.h, gc.man, gc_alloc.h, gc_cpp.h, gc_hdrs.h, gc_mark.h,
	gc_priv.h, gc_private.h, gc_typed.h, gcconfig.h,
	hpux_irix_threads.c, makefile.depend, nursery.c,
	solaris_threads.h, test.c, test_cpp.cc, weakpointer.h, cord/README,
	cord/SCOPTIONS.amiga, cord/SMakefile.amiga, cord/cord.h,
	cord/ec.h, cord/gc.h, cord/private/cord_pos.h, include/backptr.h,
	include/gc_copy_descr.h, include/gc_nursery.h: Remove obsolete/moved
	files.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@42379 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 955 insertions, 93 deletions

diff --git a/boehm-gc/linux_threads.c b/boehm-gc/linux_threads.c
index 92da410e3da..37537bcef3e 100644
--- a/boehm-gc/linux_threads.c
+++ b/boehm-gc/linux_threads.c
@@ -2,6 +2,7 @@
  * Copyright (c) 1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996 by Silicon Graphics.  All rights reserved.
  * Copyright (c) 1998 by Fergus Henderson.  All rights reserved.
+ * Copyright (c) 2000-2001 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.
@@ -17,24 +18,61 @@
  * thread package for Linux which is included in libc6.
  *
  * This code relies on implementation details of LinuxThreads,
- * (i.e. properties not guaranteed by the Pthread standard):
- *
- *	- the function GC_linux_thread_top_of_stack(void)
- *	  relies on the way LinuxThreads lays out thread stacks
- *	  in the address space.
+ * (i.e. properties not guaranteed by the Pthread standard),
+ * though this version now does less of that than the other Pthreads
+ * support code.
  *
  * 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.
+ * and thread support for some of the other Posix platforms; any changes
+ * made here may need to be reflected there too.
+ */
+/*
+ * Linux_threads.c now also includes some code to support HPUX and
+ * OSF1 (Compaq Tru64 Unix, really).  The OSF1 support is not yet
+ * functional.  The OSF1 code is based on Eric Benson's
+ * patch, though that was originally against hpux_irix_threads.  The code
+ * here is completely untested.  With 0.0000001% probability, it might
+ * actually work.
+ *
+ * Eric also suggested an alternate basis for a lock implementation in
+ * his code:
+ * + #elif defined(OSF1)
+ * +    unsigned long GC_allocate_lock = 0;
+ * +    msemaphore GC_allocate_semaphore;
+ * + #  define GC_TRY_LOCK() \
+ * +    ((msem_lock(&GC_allocate_semaphore, MSEM_IF_NOWAIT) == 0) \
+ * +     ? (GC_allocate_lock = 1) \
+ * +     : 0)
+ * + #  define GC_LOCK_TAKEN GC_allocate_lock
  */
 
 /* #define DEBUG_THREADS 1 */
 
 /* ANSI C requires that a compilation unit contains something */
-# include "gc_priv.h"
 
-# if defined(LINUX_THREADS)
+# if defined(GC_LINUX_THREADS) || defined(LINUX_THREADS) \
+     || defined(GC_HPUX_THREADS) || defined(HPUX_THREADS) \
+     || defined(GC_OSF1_THREADS) || defined(OSF1_THREADS) \
 
+# include "private/gc_priv.h"
+# ifdef THREAD_LOCAL_ALLOC
+#   if !defined(USE_PTHREAD_SPECIFIC) && !defined(USE_HPUX_TLS)
+#     include "private/specific.h"
+#   endif
+#   if defined(USE_PTHREAD_SPECIFIC)
+#     define GC_getspecific pthread_getspecific
+#     define GC_setspecific pthread_setspecific
+#     define GC_key_create pthread_key_create
+      typedef pthread_key_t GC_key_t;
+#   endif
+#   if defined(USE_HPUX_TLS)
+#     define GC_getspecific(x) (x)
+#     define GC_setspecific(key, v) ((key) = (v), 0)
+#     define GC_key_create(key, d) 0
+      typedef void * GC_key_t;
+#   endif
+# endif
+# include <stdlib.h>
 # include <pthread.h>
 # include <sched.h>
 # include <time.h>
@@ -44,8 +82,15 @@
 # include <sys/time.h>
 # include <semaphore.h>
 # include <signal.h>
+# include <sys/types.h>
+# include <sys/stat.h>
+# include <fcntl.h>
+
+#ifndef __GNUC__
+#   define __inline__
+#endif
 
-#ifdef USE_LD_WRAP
+#ifdef GC_USE_LD_WRAP
 #   define WRAP_FUNC(f) __wrap_##f
 #   define REAL_FUNC(f) __real_##f
 #else
@@ -54,6 +99,7 @@
 #   undef pthread_create
 #   undef pthread_sigmask
 #   undef pthread_join
+#   undef pthread_detach
 #endif
 
 
@@ -75,14 +121,13 @@ void GC_print_sig_mask()
 }
 #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	*/
+/* joins.								*/
+/* Protected by allocation/GC lock.					*/
+/* Some of this should be declared volatile, but that's inconsistent	*/
 /* with some library routine declarations.  		 		*/
 typedef struct GC_Thread_Rep {
     struct GC_Thread_Rep * next;  /* More recently allocated threads	*/
@@ -91,11 +136,17 @@ typedef struct GC_Thread_Rep {
 				  /* guaranteed to be dead, but we may  */
 				  /* not yet have registered the join.) */
     pthread_t id;
-    word flags;
+    short flags;
 #	define FINISHED 1   	/* Thread has exited.	*/
 #	define DETACHED 2	/* Thread is intended to be detached.	*/
 #	define MAIN_THREAD 4	/* True for the original thread only.	*/
-
+    short thread_blocked;	/* Protected by GC lock.		*/
+    				/* Treated as a boolean value.  If set,	*/
+    				/* thread will acquire GC lock before	*/
+    				/* doing any pointer manipulations, and	*/
+    				/* has set its sp value.  Thus it does	*/
+    				/* not need to be sent a signal to stop	*/
+    				/* it.					*/
     ptr_t stack_end;		/* Cold end of the stack.		*/
     ptr_t stack_ptr;  		/* Valid only when stopped.      	*/
 #   ifdef IA64
@@ -107,10 +158,262 @@ typedef struct GC_Thread_Rep {
     				/* Used only to avoid premature 	*/
 				/* reclamation of any data it might 	*/
 				/* reference.				*/
+#   ifdef THREAD_LOCAL_ALLOC
+#	if CPP_WORDSZ == 64 && defined(ALIGN_DOUBLE)
+#	    define GRANULARITY 16
+#	    define NFREELISTS 48
+#	else
+#	    define GRANULARITY 8
+#	    define NFREELISTS 64
+#	endif
+	/* The ith free list corresponds to size (i+1)*GRANULARITY */
+#	define INDEX_FROM_BYTES(n) (ADD_SLOP(n) - 1)/GRANULARITY
+#	define BYTES_FROM_INDEX(i) (((i) + 1) * GRANULARITY - EXTRA_BYTES)
+#	define SMALL_ENOUGH(bytes) (ADD_SLOP(bytes) <= NFREELISTS*GRANULARITY)
+	ptr_t ptrfree_freelists[NFREELISTS];
+	ptr_t normal_freelists[NFREELISTS];
+#	ifdef GC_GCJ_SUPPORT
+	  ptr_t gcj_freelists[NFREELISTS];
+#	endif
+		/* Free lists contain either a pointer or a small count */
+		/* reflecting the number of granules allocated at that	*/
+		/* size.						*/
+		/* 0 ==> thread-local allocation in use, free list	*/
+		/*       empty.						*/
+		/* > 0, <= DIRECT_GRANULES ==> Using global allocation,	*/
+		/*       too few objects of this size have been		*/
+		/* 	 allocated by this thread.			*/
+		/* >= HBLKSIZE  => pointer to nonempty free list.	*/
+		/* > DIRECT_GRANULES, < HBLKSIZE ==> transition to	*/
+		/*    local alloc, equivalent to 0.			*/
+#	define DIRECT_GRANULES (HBLKSIZE/GRANULARITY)
+		/* Don't use local free lists for up to this much 	*/
+		/* allocation.						*/
+#   endif
 } * GC_thread;
 
 GC_thread GC_lookup_thread(pthread_t id);
 
+static GC_bool fully_initialized = FALSE;
+
+# if defined(__GNUC__)
+    void GC_full_init() __attribute__ ((constructor));
+# else
+    void GC_full_init();
+# endif
+
+# if defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL)
+
+/* We don't really support thread-local allocation with DBG_HDRS_ALL */
+
+#ifdef USE_HPUX_TLS
+  __thread
+#endif
+GC_key_t GC_thread_key;
+
+static GC_bool keys_initialized;
+
+/* Recover the contents of the freelist array fl into the global one gfl.*/
+/* Note that the indexing scheme differs, in that gfl has finer size	*/
+/* resolution, even if not all entries are used.			*/
+/* We hold the allocator lock.						*/
+static void return_freelists(ptr_t *fl, ptr_t *gfl)
+{
+    int i;
+    ptr_t q, *qptr;
+    size_t nwords;
+
+    for (i = 0; i < NFREELISTS; ++i) {
+	nwords = (i + 1) * (GRANULARITY/sizeof(word));
+        qptr = fl + i;	
+	q = *qptr;
+	if ((word)q < HBLKSIZE) continue;
+	if (gfl[nwords] == 0) {
+	    gfl[nwords] = q;
+	} else {
+	    /* Concatenate: */
+	    for (; (word)q >= HBLKSIZE; qptr = &(obj_link(q)), q = *qptr);
+	    GC_ASSERT(0 == q);
+	    *qptr = gfl[nwords];
+	    gfl[nwords] = fl[i];
+	}
+	/* Clear fl[i], since the thread structure may hang around.	*/
+	/* Do it in a way that is likely to trap if we access it.	*/
+	fl[i] = (ptr_t)HBLKSIZE;
+    }
+}
+
+/* Each thread structure must be initialized.	*/
+/* This call must be made from the new thread.	*/
+/* Caller holds allocation lock.		*/
+void GC_init_thread_local(GC_thread p)
+{
+    int i;
+
+    if (!keys_initialized) {
+	if (0 != GC_key_create(&GC_thread_key, 0)) {
+	    ABORT("Failed to create key for local allocator");
+        }
+	keys_initialized = TRUE;
+    }
+    if (0 != GC_setspecific(GC_thread_key, p)) {
+	ABORT("Failed to set thread specific allocation pointers");
+    }
+    for (i = 0; i < NFREELISTS; ++i) {
+	p -> ptrfree_freelists[i] = (ptr_t)1;
+	p -> normal_freelists[i] = (ptr_t)1;
+#	ifdef GC_GCJ_SUPPORT
+	  p -> gcj_freelists[i] = (ptr_t)1;
+#	endif
+    }   
+}
+
+#ifdef GC_GCJ_SUPPORT
+  extern ptr_t * GC_gcjobjfreelist;
+#endif
+
+/* We hold the allocator lock.	*/
+void GC_destroy_thread_local(GC_thread p)
+{
+    /* We currently only do this from the thread itself.	*/
+	GC_ASSERT(GC_getspecific(GC_thread_key) == (void *)p);
+    return_freelists(p -> ptrfree_freelists, GC_aobjfreelist);
+    return_freelists(p -> normal_freelists, GC_objfreelist);
+#   ifdef GC_GCJ_SUPPORT
+   	return_freelists(p -> gcj_freelists, GC_gcjobjfreelist);
+#   endif
+}
+
+extern GC_PTR GC_generic_malloc_many();
+
+GC_PTR GC_local_malloc(size_t bytes)
+{
+    if (EXPECT(!SMALL_ENOUGH(bytes),0)) {
+        return(GC_malloc(bytes));
+    } else {
+	int index = INDEX_FROM_BYTES(bytes);
+	ptr_t * my_fl;
+	ptr_t my_entry;
+	GC_key_t k = GC_thread_key;
+	void * tsd;
+
+#	if defined(REDIRECT_MALLOC) && !defined(USE_PTHREAD_SPECIFIC) \
+	   || !defined(__GNUC__)
+	    if (EXPECT(0 == k, 0)) {
+		/* This can happen if we get called when the world is	*/
+		/* being initialized.  Whether we can actually complete	*/
+		/* the initialization then is unclear.			*/
+		GC_full_init();
+		k = GC_thread_key;
+	    }
+#	endif
+	tsd = GC_getspecific(GC_thread_key);
+#	ifdef GC_ASSERTIONS
+	  LOCK();
+	  GC_ASSERT(tsd == (void *)GC_lookup_thread(pthread_self()));
+	  UNLOCK();
+#	endif
+	my_fl = ((GC_thread)tsd) -> normal_freelists + index;
+	my_entry = *my_fl;
+	if (EXPECT((word)my_entry >= HBLKSIZE, 1)) {
+	    ptr_t next = obj_link(my_entry);
+	    GC_PTR result = (GC_PTR)my_entry;
+	    *my_fl = next;
+	    obj_link(my_entry) = 0;
+	    PREFETCH_FOR_WRITE(next);
+	    return result;
+	} else if ((word)my_entry - 1 < DIRECT_GRANULES) {
+	    *my_fl = my_entry + index + 1;
+            return GC_malloc(bytes);
+	} else {
+	    my_entry = GC_generic_malloc_many(BYTES_FROM_INDEX(index),
+					      NORMAL);
+	    *my_fl = my_entry;
+	    if (my_entry == 0) return GC_oom_fn(bytes);
+	    return GC_local_malloc(bytes);
+	}
+    }
+}
+
+GC_PTR GC_local_malloc_atomic(size_t bytes)
+{
+    if (EXPECT(!SMALL_ENOUGH(bytes), 0)) {
+        return(GC_malloc_atomic(bytes));
+    } else {
+	int index = INDEX_FROM_BYTES(bytes);
+	ptr_t * my_fl = ((GC_thread)GC_getspecific(GC_thread_key))
+		        -> ptrfree_freelists + index;
+	ptr_t my_entry = *my_fl;
+	if (EXPECT((word)my_entry >= HBLKSIZE, 1)) {
+	    GC_PTR result = (GC_PTR)my_entry;
+	    *my_fl = obj_link(my_entry);
+	    return result;
+	} else if ((word)my_entry - 1 < DIRECT_GRANULES) {
+	    *my_fl = my_entry + index + 1;
+            return GC_malloc_atomic(bytes);
+	} else {
+	    my_entry = GC_generic_malloc_many(BYTES_FROM_INDEX(index),
+					      PTRFREE);
+	    *my_fl = my_entry;
+	    if (my_entry == 0) return GC_oom_fn(bytes);
+	    return GC_local_malloc_atomic(bytes);
+	}
+    }
+}
+
+#ifdef GC_GCJ_SUPPORT
+
+#include "include/gc_gcj.h"
+
+#ifdef GC_ASSERTIONS
+  extern GC_bool GC_gcj_malloc_initialized;
+#endif
+
+extern int GC_gcj_kind;
+
+GC_PTR GC_local_gcj_malloc(size_t bytes,
+			   void * ptr_to_struct_containing_descr)
+{
+    GC_ASSERT(GC_gcj_malloc_initialized);
+    if (EXPECT(!SMALL_ENOUGH(bytes), 0)) {
+        return GC_gcj_malloc(bytes, ptr_to_struct_containing_descr);
+    } else {
+	int index = INDEX_FROM_BYTES(bytes);
+	ptr_t * my_fl = ((GC_thread)GC_getspecific(GC_thread_key))
+	                -> gcj_freelists + index;
+	ptr_t my_entry = *my_fl;
+	if (EXPECT((word)my_entry >= HBLKSIZE, 1)) {
+	    GC_PTR result = (GC_PTR)my_entry;
+	    GC_ASSERT(!GC_incremental);
+	    /* We assert that any concurrent marker will stop us.	*/
+	    /* Thus it is impossible for a mark procedure to see the 	*/
+	    /* allocation of the next object, but to see this object 	*/
+	    /* still containing a free list pointer.  Otherwise the 	*/
+	    /* marker might find a random "mark descriptor".		*/
+	    *my_fl = obj_link(my_entry);
+	    *(void **)result = ptr_to_struct_containing_descr; 
+	    return result;
+	} else if ((word)my_entry - 1 < DIRECT_GRANULES) {
+	    *my_fl = my_entry + index + 1;
+            return GC_gcj_malloc(bytes, ptr_to_struct_containing_descr);
+	} else {
+	    my_entry = GC_generic_malloc_many(BYTES_FROM_INDEX(index),
+					      GC_gcj_kind);
+	    *my_fl = my_entry;
+	    if (my_entry == 0) return GC_oom_fn(bytes);
+	    return GC_gcj_malloc(bytes, ptr_to_struct_containing_descr);
+	}
+    }
+}
+
+#endif /* GC_GCJ_SUPPORT */
+
+# else  /* !THREAD_LOCAL_ALLOC  && !DBG_HDRS_ALL */
+
+#   define GC_destroy_thread_local(t)
+
+# endif /* !THREAD_LOCAL_ALLOC */
+
 /*
  * The only way to suspend threads given the pthread interface is to send
  * signals.  We can't use SIGSTOP directly, because we need to get the
@@ -121,16 +424,32 @@ GC_thread GC_lookup_thread(pthread_t id);
  * so we need to reuse something else.  I chose SIGPWR.
  * (Perhaps SIGUNUSED would be a better choice.)
  */
-#define SIG_SUSPEND SIGPWR
+#ifndef SIG_SUSPEND
+#  if defined(HPUX_THREADS) || defined(GC_OSF1_THREADS)
+#   define SIG_SUSPEND _SIGRTMIN + 6
+#  else
+#   define SIG_SUSPEND SIGPWR
+#  endif
+#endif
 
-#define SIG_RESTART SIGXCPU
+#ifndef SIG_THR_RESTART
+#  if defined(HPUX_THREADS) || defined(GC_OSF1_THREADS)
+#   define SIG_THR_RESTART _SIGRTMIN + 5
+#  else
+#   define SIG_THR_RESTART SIGXCPU
+#  endif
+#endif
+
+/* SPARC/Linux doesn't properly define SIGPWR in <signal.h>.
+ * It is aliased to SIGLOST in asm/signal.h, though.		*/
+#if defined(SPARC) && !defined(SIGPWR)
+#   define SIGPWR SIGLOST
+#endif
 
 sem_t GC_suspend_ack_sem;
 
+#if !defined(HPUX_THREADS) && !defined(GC_OSF1_THREADS)
 /*
-GC_linux_thread_top_of_stack() relies on implementation details of
-LinuxThreads, namely that thread stacks are allocated on 2M boundaries
-and grow to no more than 2M.
 To make sure that we're using LinuxThreads and not some other thread
 package, we generate a dummy reference to `pthread_kill_other_threads_np'
 (was `__pthread_initial_thread_bos' but that disappeared),
@@ -138,23 +457,89 @@ which is a symbol defined in LinuxThreads, but (hopefully) not in other
 thread packages.
 */
 void (*dummy_var_to_force_linux_threads)() = pthread_kill_other_threads_np;
+#endif /* !HPUX_THREADS */
+
+#if defined(SPARC) || defined(IA64)
+  extern word GC_save_regs_in_stack();
+#endif
 
-#define LINUX_THREADS_STACK_SIZE  (2 * 1024 * 1024)
+long GC_nprocs = 1;	/* Number of processors.  We may not have	*/
+			/* access to all of them, but this is as good	*/
+			/* a guess as any ...				*/
 
-static inline ptr_t GC_linux_thread_top_of_stack(void)
+#ifdef PARALLEL_MARK
+
+# ifndef MAX_MARKERS
+#   define MAX_MARKERS 16
+# endif
+
+static ptr_t marker_sp[MAX_MARKERS] = {0};
+
+void * GC_mark_thread(void * id)
 {
-  char *sp = GC_approx_sp();
-  ptr_t tos = (ptr_t) (((unsigned long)sp | (LINUX_THREADS_STACK_SIZE - 1)) + 1);
-#if DEBUG_THREADS
-  GC_printf1("SP = %lx\n", (unsigned long)sp);
-  GC_printf1("TOS = %lx\n", (unsigned long)tos);
-#endif
-  return tos;
+  word my_mark_no = 0;
+
+  marker_sp[(word)id] = GC_approx_sp();
+  for (;; ++my_mark_no) {
+    /* GC_mark_no is passed only to allow GC_help_marker to terminate	*/
+    /* promptly.  This is important if it were called from the signal	*/
+    /* handler or from the GC lock acquisition code.  Under Linux, it's	*/
+    /* not safe to call it from a signal handler, since it uses mutexes	*/
+    /* and condition variables.  Since it is called only here, the 	*/
+    /* argument is unnecessary.						*/
+    if (my_mark_no < GC_mark_no || my_mark_no > GC_mark_no + 2) {
+	/* resynchronize if we get far off, e.g. because GC_mark_no	*/
+	/* wrapped.							*/
+	my_mark_no = GC_mark_no;
+    }
+#   ifdef DEBUG_THREADS
+	GC_printf1("Starting mark helper for mark number %ld\n", my_mark_no);
+#   endif
+    GC_help_marker(my_mark_no);
+  }
 }
 
-#if defined(SPARC) || defined(IA64)
-  extern word GC_save_regs_in_stack();
-#endif
+extern long GC_markers;		/* Number of mark threads we would	*/
+				/* like to have.  Includes the 		*/
+				/* initiating thread.			*/
+
+pthread_t GC_mark_threads[MAX_MARKERS];
+
+#define PTHREAD_CREATE REAL_FUNC(pthread_create)
+
+static void start_mark_threads()
+{
+    unsigned i;
+    pthread_attr_t attr;
+
+    if (GC_markers > MAX_MARKERS) {
+	WARN("Limiting number of mark threads\n", 0);
+	GC_markers = MAX_MARKERS;
+    }
+    if (0 != pthread_attr_init(&attr)) ABORT("pthread_attr_init failed");
+	
+    if (0 != pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED))
+	ABORT("pthread_attr_setdetachstate failed");
+#   ifdef CONDPRINT
+      if (GC_print_stats) {
+	GC_printf1("Starting %ld marker threads\n", GC_markers - 1);
+      }
+#   endif
+    for (i = 0; i < GC_markers - 1; ++i) {
+      if (0 != PTHREAD_CREATE(GC_mark_threads + i, &attr,
+			      GC_mark_thread, (void *)(word)i)) {
+	WARN("Marker thread creation failed, errno = %ld.\n", errno);
+      }
+    }
+}
+
+#else  /* !PARALLEL_MARK */
+
+static __inline__ void start_mark_threads()
+{
+}
+
+#endif /* !PARALLEL_MARK */
 
 void GC_suspend_handler(int sig)
 {
@@ -165,6 +550,12 @@ void GC_suspend_handler(int sig)
     sigset_t old_sigs;
     int i;
     sigset_t mask;
+#   ifdef PARALLEL_MARK
+	word my_mark_no = GC_mark_no;
+	/* Marker can't proceed until we acknowledge.  Thus this is	*/
+	/* guaranteed to be the mark_no correspending to our 		*/
+	/* suspension, i.e. the marker can't have incremented it yet.	*/
+#   endif
 
     if (sig != SIG_SUSPEND) ABORT("Bad signal in suspend_handler");
 
@@ -192,11 +583,11 @@ void GC_suspend_handler(int sig)
     sem_post(&GC_suspend_ack_sem);
 
     /* Wait until that thread tells us to restart by sending    */
-    /* this thread a SIG_RESTART signal.			*/
-    /* SIG_RESTART should be masked at this point.  Thus there	*/
+    /* this thread a SIG_THR_RESTART signal.			*/
+    /* SIG_THR_RESTART should be masked at this point.  Thus there	*/
     /* is no race.						*/
     if (sigfillset(&mask) != 0) ABORT("sigfillset() failed");
-    if (sigdelset(&mask, SIG_RESTART) != 0) ABORT("sigdelset() failed");
+    if (sigdelset(&mask, SIG_THR_RESTART) != 0) ABORT("sigdelset() failed");
 #   ifdef NO_SIGNALS
       if (sigdelset(&mask, SIGINT) != 0) ABORT("sigdelset() failed");
       if (sigdelset(&mask, SIGQUIT) != 0) ABORT("sigdelset() failed");
@@ -206,7 +597,7 @@ void GC_suspend_handler(int sig)
     do {
 	    me->signal = 0;
 	    sigsuspend(&mask);             /* Wait for signal */
-    } while (me->signal != SIG_RESTART);
+    } while (me->signal != SIG_THR_RESTART);
 
 #if DEBUG_THREADS
     GC_printf1("Continuing 0x%x\n", my_thread);
@@ -217,15 +608,15 @@ void GC_restart_handler(int sig)
 {
     GC_thread me;
 
-    if (sig != SIG_RESTART) ABORT("Bad signal in suspend_handler");
+    if (sig != SIG_THR_RESTART) ABORT("Bad signal in suspend_handler");
 
-    /* Let the GC_suspend_handler() know that we got a SIG_RESTART. */
+    /* Let the GC_suspend_handler() know that we got a SIG_THR_RESTART. */
     /* 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.				*/
     me = GC_lookup_thread(pthread_self());
-    me->signal = SIG_RESTART;
+    me->signal = SIG_THR_RESTART;
 
     /*
     ** Note: even if we didn't do anything useful here,
@@ -240,11 +631,29 @@ void GC_restart_handler(int sig)
 #endif
 }
 
+/* Defining INSTALL_LOOPING_SEGV_HANDLER causes SIGSEGV and SIGBUS to 	*/
+/* result in an infinite loop in a signal handler.  This can be very	*/
+/* useful for debugging, since (as of RH7) gdb still seems to have	*/
+/* serious problems with threads.					*/
+#ifdef INSTALL_LOOPING_SEGV_HANDLER
+void GC_looping_handler(int sig)
+{
+    GC_printf3("Signal %ld in thread %lx, pid %ld\n",
+	       sig, pthread_self(), getpid());
+    for (;;);
+}
+#endif
+
 GC_bool GC_thr_initialized = FALSE;
 
 # 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)
@@ -257,16 +666,15 @@ GC_thread GC_new_thread(pthread_t id)
     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_generic_malloc_inner(sizeof(struct GC_Thread_Rep), NORMAL);
+        	 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; */
+    GC_ASSERT(result -> flags == 0 && result -> thread_blocked == 0);
     return(result);
 }
 
@@ -288,6 +696,7 @@ void GC_delete_thread(pthread_t id)
     } else {
         prev -> next = p -> next;
     }
+    GC_INTERNAL_FREE(p);
 }
 
 /* If a thread has been joined, but we have not yet		*/
@@ -309,6 +718,7 @@ void GC_delete_gc_thread(pthread_t id, GC_thread gc_id)
     } else {
         prev -> next = p -> next;
     }
+    GC_INTERNAL_FREE(p);
 }
 
 /* Return a GC_thread corresponding to a given thread_t.	*/
@@ -326,8 +736,8 @@ GC_thread GC_lookup_thread(pthread_t id)
     return(p);
 }
 
-/* There seems to be a very rare thread stopping problem.  To help us 	*/
-/* debug that, we save the ids of the stopping thread. 			*/
+/* There seems to be a very rare thread stopping problem.  To help us  */
+/* debug that, we save the ids of the stopping thread. */
 pthread_t GC_stopping_thread;
 int GC_stopping_pid;
 
@@ -340,12 +750,23 @@ void GC_stop_world()
     register int n_live_threads = 0;
     register int result;
 
-    GC_stopping_thread = my_thread;	/* debugging only.	*/
-    GC_stopping_pid = getpid();		/* debugging only.	*/
+    GC_stopping_thread = my_thread;    /* debugging only.      */
+    GC_stopping_pid = getpid();                /* debugging only.      */
+
+    /* Make sure all free list construction has stopped before we start. */
+    /* No new construction can start, since free list construction is	*/
+    /* required to acquire and release the GC lock before it starts,	*/
+    /* and we have the lock.						*/
+#   ifdef PARALLEL_MARK
+      GC_acquire_mark_lock();
+      GC_ASSERT(GC_fl_builder_count == 0);
+      /* We should have previously waited for it to become zero. */
+#   endif /* PARALLEL_MARK */
     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) continue;
+	    if (p -> thread_blocked) /* Will wait */ continue;
             n_live_threads++;
 	    #if DEBUG_THREADS
 	      GC_printf1("Sending suspend signal to 0x%x\n", p -> id);
@@ -365,14 +786,19 @@ void GC_stop_world()
       }
     }
     for (i = 0; i < n_live_threads; i++) {
-    	sem_wait(&GC_suspend_ack_sem);
+    	if (0 != sem_wait(&GC_suspend_ack_sem))
+	    ABORT("sem_wait in handler failed");
     }
+#   ifdef PARALLEL_MARK
+      GC_release_mark_lock();
+#   endif
     #if DEBUG_THREADS
-    GC_printf1("World stopped 0x%x\n", pthread_self());
+      GC_printf1("World stopped 0x%x\n", pthread_self());
     #endif
 }
 
-/* Caller holds allocation lock.	*/
+/* Caller holds allocation lock, and has held it continuously since	*/
+/* the world stopped.							*/
 void GC_start_world()
 {
     pthread_t my_thread = pthread_self();
@@ -389,11 +815,12 @@ void GC_start_world()
       for (p = GC_threads[i]; p != 0; p = p -> next) {
         if (p -> id != my_thread) {
             if (p -> flags & FINISHED) continue;
+	    if (p -> thread_blocked) continue;
             n_live_threads++;
 	    #if DEBUG_THREADS
 	      GC_printf1("Sending restart signal to 0x%x\n", p -> id);
 	    #endif
-            result = pthread_kill(p -> id, SIG_RESTART);
+            result = pthread_kill(p -> id, SIG_THR_RESTART);
 	    switch(result) {
                 case ESRCH:
                     /* Not really there anymore.  Possible? */
@@ -438,11 +865,11 @@ void GC_push_all_stacks()
       for (p = GC_threads[i]; p != 0; p = p -> next) {
         if (p -> flags & FINISHED) continue;
         if (pthread_equal(p -> id, me)) {
-#  ifdef SPARC
-	    lo = (ptr_t)GC_save_regs_in_stack();
-#  else
-	    lo = GC_approx_sp();
-#  endif
+#  	    ifdef SPARC
+	        lo = (ptr_t)GC_save_regs_in_stack();
+#  	    else
+ 	        lo = GC_approx_sp();
+#           endif
 	    IF_IA64(bs_hi = (ptr_t)GC_save_regs_in_stack();)
 	} else {
 	    lo = p -> stack_ptr;
@@ -462,7 +889,12 @@ void GC_push_all_stacks()
 		(unsigned long) lo, (unsigned long) hi);
         #endif
 	if (0 == lo) ABORT("GC_push_all_stacks: sp not set!\n");
-        GC_push_all_stack(lo, hi);
+#       ifdef STACK_GROWS_UP
+	  /* We got them backwards! */
+          GC_push_all_stack(hi, lo);
+#       else
+          GC_push_all_stack(lo, hi);
+#	endif
 #	ifdef IA64
           if (pthread_equal(p -> id, me)) {
 	    GC_push_all_eager(bs_lo, bs_hi);
@@ -474,6 +906,69 @@ void GC_push_all_stacks()
     }
 }
 
+#ifdef USE_PROC_FOR_LIBRARIES
+int GC_segment_is_thread_stack(ptr_t lo, ptr_t hi)
+{
+    int i;
+    GC_thread p;
+    
+#   ifdef PARALLEL_MARK
+      for (i = 0; i < GC_markers; ++i) {
+	if (marker_sp[i] > lo & marker_sp[i] < hi) return 1;
+      }
+#   endif
+    for (i = 0; i < THREAD_TABLE_SZ; i++) {
+      for (p = GC_threads[i]; p != 0; p = p -> next) {
+	if (0 != p -> stack_end) {
+#	  ifdef STACK_GROWS_UP
+            if (p -> stack_end >= lo && p -> stack_end < hi) return 1;
+#	  else /* STACK_GROWS_DOWN */
+            if (p -> stack_end > lo && p -> stack_end <= hi) return 1;
+#	  endif
+	}
+      }
+    }
+    return 0;
+}
+#endif /* USE_PROC_FOR_LIBRARIES */
+
+#ifdef LINUX_THREADS
+/* Return the number of processors, or i<= 0 if it can't be determined.	*/
+int GC_get_nprocs()
+{
+    /* Should be "return sysconf(_SC_NPROCESSORS_ONLN);" but that	*/
+    /* appears to be buggy in many cases.				*/
+    /* We look for lines "cpu<n>" in /proc/stat.			*/
+#   define STAT_BUF_SIZE 4096
+#   if defined(GC_USE_LD_WRAP)
+#	define STAT_READ __real_read
+#   else
+#	define STAT_READ read
+#   endif    
+    char stat_buf[STAT_BUF_SIZE];
+    int f;
+    char c;
+    word result = 1;
+	/* Some old kernels only have a single "cpu nnnn ..."	*/
+	/* entry in /proc/stat.  We identify those as 		*/
+	/* uniprocessors.					*/
+    size_t i, len = 0;
+
+    f = open("/proc/stat", O_RDONLY);
+    if (f < 0 || (len = STAT_READ(f, stat_buf, STAT_BUF_SIZE)) < 100) {
+	WARN("Couldn't read /proc/stat\n", 0);
+	return -1;
+    }
+    for (i = 0; i < len - 100; ++i) {
+        if (stat_buf[i] == '\n' && stat_buf[i+1] == 'c'
+	    && stat_buf[i+2] == 'p' && stat_buf[i+3] == 'u') {
+	    int cpu_no = atoi(stat_buf + i + 4);
+	    if (cpu_no >= result) result = cpu_no + 1;
+	}
+    }
+    return result;
+}
+#endif /* LINUX_THREADS */
 
 /* We hold the allocation lock.	*/
 void GC_thr_init()
@@ -492,33 +987,109 @@ void GC_thr_init()
     if (sigfillset(&act.sa_mask) != 0) {
     	ABORT("sigfillset() failed");
     }
-
 #   ifdef NO_SIGNALS
       if (sigdelset(&act.sa_mask, SIGINT) != 0
 	  || sigdelset(&act.sa_mask, SIGQUIT != 0)
-	  || sigdelset(&act.sa_mask, SIGTERM != 0)
-	  || sigdelset(&act.sa_mask, SIGABRT != 0)) {
+	  || sigdelset(&act.sa_mask, SIGABRT != 0)
+	  || sigdelset(&act.sa_mask, SIGTERM != 0)) {
         ABORT("sigdelset() failed");
       }
 #   endif
 
-    /* SIG_RESTART is unmasked by the handler when necessary. 	*/
+    /* SIG_THR_RESTART is unmasked by the handler when necessary. 	*/
     act.sa_handler = GC_suspend_handler;
     if (sigaction(SIG_SUSPEND, &act, NULL) != 0) {
     	ABORT("Cannot set SIG_SUSPEND handler");
     }
 
     act.sa_handler = GC_restart_handler;
-    if (sigaction(SIG_RESTART, &act, NULL) != 0) {
-    	ABORT("Cannot set SIG_SUSPEND handler");
+    if (sigaction(SIG_THR_RESTART, &act, NULL) != 0) {
+    	ABORT("Cannot set SIG_THR_RESTART handler");
     }
+#   ifdef INSTALL_LOOPING_SEGV_HANDLER
+        act.sa_handler = GC_looping_handler;
+	if (sigaction(SIGSEGV, &act, NULL) != 0
+	    || sigaction(SIGBUS, &act, NULL) != 0) {
+	    ABORT("Cannot set SIGSEGV or SIGBUS looping handler");
+	}
+#   endif  /* INSTALL_LOOPING_SEGV_HANDLER */
 
     /* Add the initial thread, so we can stop it.	*/
       t = GC_new_thread(pthread_self());
       t -> stack_ptr = (ptr_t)(&dummy);
       t -> flags = DETACHED | MAIN_THREAD;
+
+    /* Set GC_nprocs.  */
+      {
+	char * nprocs_string = GETENV("GC_NPROCS");
+	GC_nprocs = -1;
+	if (nprocs_string != NULL) GC_nprocs = atoi(nprocs_string);
+      }
+      if (GC_nprocs <= 0) {
+#       if defined(HPUX_THREADS)
+	  GC_nprocs = pthread_num_processors_np();
+#       endif
+#       if defined(OSF1_THREADS)
+          GC_nprocs = 1;
+#       endif
+#	ifdef LINUX_THREADS
+          GC_nprocs = GC_get_nprocs();
+#	endif
+      }
+      if (GC_nprocs <= 0) {
+	WARN("GC_get_nprocs() returned %ld\n", GC_nprocs);
+	GC_nprocs = 2;
+#	ifdef PARALLEL_MARK
+	  GC_markers = 1;
+#	endif
+      } else {
+#	ifdef PARALLEL_MARK
+	  GC_markers = GC_nprocs;
+#	endif
+      }
+#   ifdef PARALLEL_MARK
+#     ifdef CONDPRINT
+        if (GC_print_stats) {
+          GC_printf2("Number of processors = %ld, "
+		 "number of marker threads = %ld\n", GC_nprocs, GC_markers);
+	}
+#     endif
+      if (GC_markers == 1) {
+	GC_parallel = FALSE;
+#	ifdef CONDPRINT
+	  if (GC_print_stats) {
+	    GC_printf0("Single marker thread, turning off parallel marking\n");
+	  }
+#	endif
+      } else {
+	GC_parallel = TRUE;
+      }
+#   endif
+}
+
+
+/* Perform all initializations, including those that	*/
+/* may require allocation.				*/
+/* Called as constructor without allocation lock.	*/
+/* Must be called before a second thread is created.	*/
+void GC_full_init()
+{
+    if (fully_initialized) return;
+    if (!GC_is_initialized) GC_init();
+    /* If we are using a parallel marker, start the helper threads.  */
+#     ifdef PARALLEL_MARK
+        if (GC_parallel) start_mark_threads();
+#     endif
+    /* Initialize thread local free lists if used.	*/
+#   if defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL)
+      LOCK();
+      GC_init_thread_local(GC_lookup_thread(pthread_self()));
+      UNLOCK();
+#   endif
+    fully_initialized = TRUE;
 }
 
+
 int WRAP_FUNC(pthread_sigmask)(int how, const sigset_t *set, sigset_t *oset)
 {
     sigset_t fudged_set;
@@ -531,6 +1102,56 @@ int WRAP_FUNC(pthread_sigmask)(int how, const sigset_t *set, sigset_t *oset)
     return(REAL_FUNC(pthread_sigmask)(how, set, oset));
 }
 
+/* Wrappers for functions that are likely to block for an appreciable	*/
+/* length of time.  Must be called in pairs, if at all.			*/
+/* Nothing much beyond the system call itself should be executed	*/
+/* between these.							*/
+
+void GC_start_blocking(void) {
+#   define SP_SLOP 128
+    GC_thread me;
+    LOCK();
+    me = GC_lookup_thread(pthread_self());
+    GC_ASSERT(!(me -> thread_blocked));
+#   ifdef SPARC
+	me -> stack_ptr = (ptr_t)GC_save_regs_in_stack();
+#   else
+	me -> stack_ptr = (ptr_t)GC_approx_sp();
+#   endif
+#   ifdef IA64
+	me -> backing_store_ptr = (ptr_t)GC_save_regs_in_stack() + SP_SLOP;
+#   endif
+    /* Add some slop to the stack pointer, since the wrapped call may 	*/
+    /* end up pushing more callee-save registers.			*/
+#   ifdef STACK_GROWS_UP
+	me -> stack_ptr += SP_SLOP;
+#   else
+	me -> stack_ptr -= SP_SLOP;
+#   endif
+    me -> thread_blocked = TRUE;
+    UNLOCK();
+}
+
+GC_end_blocking(void) {
+    GC_thread me;
+    LOCK();   /* This will block if the world is stopped.	*/
+    me = GC_lookup_thread(pthread_self());
+    GC_ASSERT(me -> thread_blocked);
+    me -> thread_blocked = FALSE;
+    UNLOCK();
+}
+    
+/* A wrapper for the standard C sleep function	*/
+int WRAP_FUNC(sleep) (unsigned int seconds)
+{
+    int result;
+
+    GC_start_blocking();
+    result = REAL_FUNC(sleep)(seconds);
+    GC_end_blocking();
+    return result;
+}
+
 struct start_info {
     void *(*start_routine)(void *);
     void *arg;
@@ -539,19 +1160,27 @@ struct start_info {
 				/* parent hasn't yet noticed.		*/
 };
 
-
+/* Called at thread exit.				*/
+/* Never called for main thread.  That's OK, since it	*/
+/* results in at most a tiny one-time leak.  And 	*/
+/* linuxthreads doesn't reclaim the main threads 	*/
+/* resources or id anyway.				*/
 void GC_thread_exit_proc(void *arg)
 {
     GC_thread me;
-    struct start_info * si = arg;
 
     LOCK();
     me = GC_lookup_thread(pthread_self());
+    GC_destroy_thread_local(me);
     if (me -> flags & DETACHED) {
     	GC_delete_thread(pthread_self());
     } else {
 	me -> flags |= FINISHED;
     }
+#   if defined(THREAD_LOCAL_ALLOC) && !defined(USE_PTHREAD_SPECIFIC) \
+       && !defined(USE_HPUX_TLS) && !defined(DBG_HDRS_ALL)
+      GC_remove_specific(GC_thread_key);
+#   endif
     if (GC_incremental && GC_collection_in_progress()) {
 	int old_gc_no = GC_gc_no;
 
@@ -581,10 +1210,34 @@ int WRAP_FUNC(pthread_join)(pthread_t thread, void **retval)
     /* cant have been recycled by pthreads.				*/
     UNLOCK();
     result = REAL_FUNC(pthread_join)(thread, retval);
+    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
+WRAP_FUNC(pthread_detach)(pthread_t thread)
+{
+    int result;
+    GC_thread thread_gc_id;
+    
     LOCK();
-    /* Here the pthread thread id may have been recycled. */
-    GC_delete_gc_thread(thread, thread_gc_id);
+    thread_gc_id = GC_lookup_thread(thread);
     UNLOCK();
+    result = REAL_FUNC(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;
 }
 
@@ -636,8 +1289,14 @@ void * GC_start_routine(void * arg)
 	GC_printf1("start_routine = 0x%lx\n", start);
 #   endif
     start_arg = si -> arg;
-    sem_post(&(si -> registered));
-    pthread_cleanup_push(GC_thread_exit_proc, si);
+    sem_post(&(si -> registered));	/* Last action on si.	*/
+    					/* OK to deallocate.	*/
+    pthread_cleanup_push(GC_thread_exit_proc, 0);
+#   if defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL)
+ 	LOCK();
+        GC_init_thread_local(me);
+	UNLOCK();
+#   endif
     result = (*start)(start_arg);
 #if DEBUG_THREADS
         GC_printf1("Finishing thread 0x%x\n", pthread_self());
@@ -659,15 +1318,16 @@ WRAP_FUNC(pthread_create)(pthread_t *new_thread,
     int result;
     GC_thread t;
     pthread_t my_new_thread;
-    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)); 
+    struct start_info * si; 
 	/* This is otherwise saved only in an area mmapped by the thread */
 	/* library, which isn't visible to the collector.		 */
-
+ 
+    LOCK();
+    si = (struct start_info *)GC_INTERNAL_MALLOC(sizeof(struct start_info), NORMAL);
+    UNLOCK();
+    if (!fully_initialized) GC_full_init();
     if (0 == si) return(ENOMEM);
     sem_init(&(si -> registered), 0, 0);
     si -> start_routine = start_routine;
@@ -675,12 +1335,10 @@ WRAP_FUNC(pthread_create)(pthread_t *new_thread,
     LOCK();
     if (!GC_thr_initialized) GC_thr_init();
     if (NULL == attr) {
-        stack = 0;
-	(void) pthread_attr_init(&new_attr);
+	detachstate = PTHREAD_CREATE_JOINABLE;
     } else {
-        new_attr = *attr;
+        pthread_attr_getdetachstate(attr, &detachstate);
     }
-    pthread_attr_getdetachstate(&new_attr, &detachstate);
     if (PTHREAD_CREATE_DETACHED == detachstate) my_flags |= DETACHED;
     si -> flags = my_flags;
     UNLOCK();
@@ -688,7 +1346,7 @@ WRAP_FUNC(pthread_create)(pthread_t *new_thread,
         GC_printf1("About to start new thread from thread 0x%X\n",
 		   pthread_self());
 #   endif
-    result = REAL_FUNC(pthread_create)(new_thread, &new_attr, GC_start_routine, si);
+    result = REAL_FUNC(pthread_create)(new_thread, attr, GC_start_routine, si);
 #   ifdef DEBUG_THREADS
         GC_printf1("Started thread 0x%X\n", *new_thread);
 #   endif
@@ -696,20 +1354,113 @@ WRAP_FUNC(pthread_create)(pthread_t *new_thread,
     /* 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.					*/
-        if (0 != sem_wait(&(si -> registered))) ABORT("sem_wait failed");
+        while (0 != sem_wait(&(si -> registered))) {
+	    if (EINTR != errno) ABORT("sem_wait failed");
+	}
         sem_destroy(&(si -> registered));
-    /* pthread_attr_destroy(&new_attr); */
-    /* pthread_attr_destroy(&new_attr); */
+	LOCK();
+	GC_INTERNAL_FREE(si);
+	UNLOCK();
     return(result);
 }
 
-#if defined(USE_SPIN_LOCK)
+#ifdef GENERIC_COMPARE_AND_SWAP
+  pthread_mutex_t GC_compare_and_swap_lock = PTHREAD_MUTEX_INITIALIZER;
+
+  GC_bool GC_compare_and_exchange(volatile GC_word *addr,
+  			          GC_word old, GC_word new_val)
+  {
+    GC_bool result;
+    pthread_mutex_lock(&GC_compare_and_swap_lock);
+    if (*addr == old) {
+      *addr = new_val;
+      result = TRUE;
+    } else {
+      result = FALSE;
+    }
+    pthread_mutex_unlock(&GC_compare_and_swap_lock);
+    return result;
+  }
+  
+  GC_word GC_atomic_add(volatile GC_word *addr, GC_word how_much)
+  {
+    GC_word old;
+    pthread_mutex_lock(&GC_compare_and_swap_lock);
+    old = *addr;
+    *addr = old + how_much;
+    pthread_mutex_unlock(&GC_compare_and_swap_lock);
+    return old;
+  }
+
+#endif /* GENERIC_COMPARE_AND_SWAP */
+/* Spend a few cycles in a way that can't introduce contention with	*/
+/* othre threads.							*/
+void GC_pause()
+{
+    int i;
+    volatile word dummy = 0;
+
+    for (i = 0; i < 10; ++i) { 
+#     ifdef __GNUC__
+        __asm__ __volatile__ (" " : : : "memory");
+#     else
+	/* Something that's unlikely to be optimized away. */
+	GC_noop(++dummy);
+#     endif
+    }
+}
+    
+#define SPIN_MAX 1024	/* Maximum number of calls to GC_pause before	*/
+			/* give up.					*/
 
 VOLATILE GC_bool GC_collecting = 0;
 			/* A hint that we're in the collector and       */
                         /* holding the allocation lock for an           */
                         /* extended period.                             */
 
+#if !defined(USE_SPIN_LOCK) || defined(PARALLEL_MARK)
+/* If we don't want to use the below spinlock implementation, either	*/
+/* because we don't have a GC_test_and_set implementation, or because 	*/
+/* we don't want to risk sleeping, we can still try spinning on 	*/
+/* pthread_mutex_trylock for a while.  This appears to be very		*/
+/* beneficial in many cases.						*/
+/* I suspect that under high contention this is nearly always better	*/
+/* than the spin lock.  But it's a bit slower on a uniprocessor.	*/
+/* Hence we still default to the spin lock.				*/
+/* This is also used to acquire the mark lock for the parallel		*/
+/* marker.								*/
+
+/* Here we use a strict exponential backoff scheme.  I don't know 	*/
+/* whether that's better or worse than the above.  We eventually 	*/
+/* yield by calling pthread_mutex_lock(); it never makes sense to	*/
+/* explicitly sleep.							*/
+
+void GC_generic_lock(pthread_mutex_t * lock)
+{
+    unsigned pause_length = 1;
+    unsigned i;
+    
+    if (0 == pthread_mutex_trylock(lock)) return;
+    for (; pause_length <= SPIN_MAX; pause_length <<= 1) {
+	for (i = 0; i < pause_length; ++i) {
+	    GC_pause();
+	}
+        switch(pthread_mutex_trylock(lock)) {
+	    case 0:
+		return;
+	    case EBUSY:
+		break;
+	    default:
+		ABORT("Unexpected error from pthread_mutex_trylock");
+        }
+    }
+    pthread_mutex_lock(lock);
+}
+
+#endif /* !USE_SPIN_LOCK || PARALLEL_MARK */
+
+#if defined(USE_SPIN_LOCK)
+
 /* Reasonably fast spin locks.  Basically the same implementation */
 /* as STL alloc.h.  This isn't really the right way to do this.   */
 /* but until the POSIX scheduling mess gets straightened out ...  */
@@ -720,25 +1471,22 @@ volatile unsigned int GC_allocate_lock = 0;
 void GC_lock()
 {
 #   define low_spin_max 30  /* spin cycles if we suspect uniprocessor */
-#   define high_spin_max 1000 /* spin cycles for multiprocessor */
+#   define high_spin_max SPIN_MAX /* 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_test_and_set(&GC_allocate_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 (GC_collecting || GC_nprocs == 1) goto yield;
         if (i < my_last_spins/2 || GC_allocate_lock) {
-            PAUSE; 
+            GC_pause();
             continue;
         }
         if (!GC_test_and_set(&GC_allocate_lock)) {
@@ -768,8 +1516,8 @@ yield:
 	} else {
 	    struct timespec ts;
 	
-	    if (i > 26) i = 26;
-			/* Don't wait for more than about 60msecs, even	*/
+	    if (i > 24) i = 24;
+			/* Don't wait for more than about 15msecs, even	*/
 			/* under extreme contention.			*/
 	    ts.tv_sec = 0;
 	    ts.tv_nsec = 1 << i;
@@ -778,7 +1526,121 @@ yield:
     }
 }
 
-#endif /* known architecture */
+#else  /* !USE_SPINLOCK */
+
+void GC_lock()
+{
+    if (1 == GC_nprocs || GC_collecting) {
+	pthread_mutex_lock(&GC_allocate_ml);
+    } else {
+        GC_generic_lock(&GC_allocate_ml);
+    }
+}
+
+#endif /* !USE_SPINLOCK */
+
+#ifdef PARALLEL_MARK
+
+#ifdef GC_ASSERTIONS
+  pthread_t GC_mark_lock_holder = NO_THREAD;
+#endif
+
+#ifdef IA64
+  /* Ugly workaround for a linux threads bug in the final versions      */
+  /* of glibc2.1.  Pthread_mutex_trylock sets the mutex owner           */
+  /* field even when it fails to acquire the mutex.  This causes        */
+  /* pthread_cond_wait to die.  Remove for glibc2.2.                    */
+  /* According to the man page, we should use                           */
+  /* PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP, but that isn't actually   */
+  /* defined.                                                           */
+  static pthread_mutex_t mark_mutex =
+        {0, 0, 0, PTHREAD_MUTEX_ERRORCHECK_NP, {0, 0}};
+#else
+  static pthread_mutex_t mark_mutex = PTHREAD_MUTEX_INITIALIZER;
+#endif
+
+static pthread_cond_t mark_cv = PTHREAD_COND_INITIALIZER;
+
+static pthread_cond_t builder_cv = PTHREAD_COND_INITIALIZER;
+
+void GC_acquire_mark_lock()
+{
+/*
+    if (pthread_mutex_lock(&mark_mutex) != 0) {
+	ABORT("pthread_mutex_lock failed");
+    }
+*/
+    GC_generic_lock(&mark_mutex);
+#   ifdef GC_ASSERTIONS
+	GC_mark_lock_holder = pthread_self();
+#   endif
+}
+
+void GC_release_mark_lock()
+{
+    GC_ASSERT(GC_mark_lock_holder == pthread_self());
+#   ifdef GC_ASSERTIONS
+	GC_mark_lock_holder = NO_THREAD;
+#   endif
+    if (pthread_mutex_unlock(&mark_mutex) != 0) {
+	ABORT("pthread_mutex_unlock failed");
+    }
+}
+
+void GC_wait_marker()
+{
+    GC_ASSERT(GC_mark_lock_holder == pthread_self());
+#   ifdef GC_ASSERTIONS
+	GC_mark_lock_holder = NO_THREAD;
+#   endif
+    if (pthread_cond_wait(&mark_cv, &mark_mutex) != 0) {
+	ABORT("pthread_cond_wait failed");
+    }
+    GC_ASSERT(GC_mark_lock_holder == NO_THREAD);
+#   ifdef GC_ASSERTIONS
+	GC_mark_lock_holder = pthread_self();
+#   endif
+}
+
+void GC_wait_builder()
+{
+    GC_ASSERT(GC_mark_lock_holder == pthread_self());
+#   ifdef GC_ASSERTIONS
+	GC_mark_lock_holder = NO_THREAD;
+#   endif
+    if (pthread_cond_wait(&builder_cv, &mark_mutex) != 0) {
+	ABORT("pthread_cond_wait failed");
+    }
+    GC_ASSERT(GC_mark_lock_holder == NO_THREAD);
+#   ifdef GC_ASSERTIONS
+	GC_mark_lock_holder = pthread_self();
+#   endif
+}
+
+void GC_notify_all_marker()
+{
+    if (pthread_cond_broadcast(&mark_cv) != 0) {
+	ABORT("pthread_cond_broadcast failed");
+    }
+}
+
+void GC_notify_all_builder()
+{
+    GC_ASSERT(GC_mark_lock_holder == pthread_self());
+    if (pthread_cond_broadcast(&builder_cv) != 0) {
+	ABORT("pthread_cond_broadcast failed");
+    }
+}
+
+void GC_wait_for_reclaim()
+{
+    GC_acquire_mark_lock();
+    while (GC_fl_builder_count > 0) {
+	GC_wait_builder();
+    }
+    GC_release_mark_lock();
+}
+#endif /* PARALLEL_MARK */
 
 # endif /* LINUX_THREADS */