Initial revision

1 files changed, 754 insertions, 0 deletions

diff --git a/gc/gc.h b/gc/gc.h
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+++ b/gc/gc.h
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+/* 
+ * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
+ * Copyright (c) 1991-1995 by Xerox Corporation.  All rights reserved.
+ * Copyright 1996 by Silicon Graphics.  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.
+ */
+
+/*
+ * Note that this defines a large number of tuning hooks, which can
+ * safely be ignored in nearly all cases.  For normal use it suffices
+ * to call only GC_MALLOC and perhaps GC_REALLOC.
+ * For better performance, also look at GC_MALLOC_ATOMIC, and
+ * GC_enable_incremental.  If you need an action to be performed
+ * immediately before an object is collected, look at GC_register_finalizer.
+ * If you are using Solaris threads, look at the end of this file.
+ * Everything else is best ignored unless you encounter performance
+ * problems.
+ */
+ 
+#ifndef _GC_H
+
+# define _GC_H
+# define __GC
+# include <stddef.h>
+
+#if defined(__CYGWIN32__) && defined(GC_USE_DLL)
+#include "libgc_globals.h"
+#endif
+
+#if defined(_MSC_VER) && defined(_DLL)
+# ifdef GC_BUILD
+#   define GC_API __declspec(dllexport)
+# else
+#   define GC_API __declspec(dllimport)
+# endif
+#endif
+
+#if defined(__WATCOMC__) && defined(GC_DLL)
+# ifdef GC_BUILD
+#   define GC_API extern __declspec(dllexport)
+# else
+#   define GC_API extern __declspec(dllimport)
+# endif
+#endif
+
+#ifndef GC_API
+#define GC_API extern
+#endif
+
+# if defined(__STDC__) || defined(__cplusplus)
+#   define GC_PROTO(args) args
+    typedef void * GC_PTR;
+# else
+#   define GC_PROTO(args) ()
+    typedef char * GC_PTR;
+#  endif
+
+# ifdef __cplusplus
+    extern "C" {
+# endif
+
+
+/* Define word and signed_word to be unsigned and signed types of the 	*/
+/* size as char * or void *.  There seems to be no way to do this	*/
+/* even semi-portably.  The following is probably no better/worse 	*/
+/* than almost anything else.						*/
+/* The ANSI standard suggests that size_t and ptr_diff_t might be 	*/
+/* better choices.  But those appear to have incorrect definitions	*/
+/* on may systems.  Notably "typedef int size_t" seems to be both	*/
+/* frequent and WRONG.							*/
+typedef unsigned long GC_word;
+typedef long GC_signed_word;
+
+/* Public read-only variables */
+
+GC_API GC_word GC_gc_no;/* Counter incremented per collection.  	*/
+			/* Includes empty GCs at startup.		*/
+			
+
+/* Public R/W variables */
+
+GC_API GC_PTR (*GC_oom_fn) GC_PROTO((size_t bytes_requested));
+			/* When there is insufficient memory to satisfy */
+			/* an allocation request, we return		*/
+			/* (*GC_oom_fn)().  By default this just	*/
+			/* returns 0.					*/
+			/* If it returns, it must return 0 or a valid	*/
+			/* pointer to a previously allocated heap 	*/
+			/* object.					*/
+
+GC_API int GC_find_leak;
+			/* Do not actually garbage collect, but simply	*/
+			/* report inaccessible memory that was not	*/
+			/* deallocated with GC_free.  Initial value	*/
+			/* is determined by FIND_LEAK macro.		*/
+
+GC_API int GC_quiet;	/* Disable statistics output.  Only matters if	*/
+			/* collector has been compiled with statistics	*/
+			/* enabled.  This involves a performance cost,	*/
+			/* and is thus not the default.			*/
+
+GC_API int GC_finalize_on_demand;
+			/* If nonzero, finalizers will only be run in 	*/
+			/* response to an eplit GC_invoke_finalizers	*/
+			/* call.  The default is determined by whether	*/
+			/* the FINALIZE_ON_DEMAND macro is defined	*/
+			/* when the collector is built.			*/
+
+GC_API int GC_java_finalization;
+			/* Mark objects reachable from finalizable 	*/
+			/* objects in a separate postpass.  This makes	*/
+			/* it a bit safer to use non-topologically-	*/
+			/* ordered finalization.  Default value is	*/
+			/* determined by JAVA_FINALIZATION macro.	*/
+
+GC_API int GC_dont_gc;	/* Dont collect unless explicitly requested, e.g. */
+			/* because it's not safe.			  */
+
+GC_API int GC_dont_expand;
+			/* Dont expand heap unless explicitly requested */
+			/* or forced to.				*/
+
+GC_API int GC_full_freq;    /* Number of partial collections between	*/
+			    /* full collections.  Matters only if	*/
+			    /* GC_incremental is set.			*/
+			
+GC_API GC_word GC_non_gc_bytes;
+			/* Bytes not considered candidates for collection. */
+			/* Used only to control scheduling of collections. */
+
+GC_API GC_word GC_free_space_divisor;
+			/* We try to make sure that we allocate at 	*/
+			/* least N/GC_free_space_divisor bytes between	*/
+			/* collections, where N is the heap size plus	*/
+			/* a rough estimate of the root set size.	*/
+			/* Initially, GC_free_space_divisor = 4.	*/
+			/* Increasing its value will use less space	*/
+			/* but more collection time.  Decreasing it	*/
+			/* will appreciably decrease collection time	*/
+			/* at the expense of space.			*/
+			/* GC_free_space_divisor = 1 will effectively	*/
+			/* disable collections.				*/
+
+GC_API GC_word GC_max_retries;
+			/* The maximum number of GCs attempted before	*/
+			/* reporting out of memory after heap		*/
+			/* expansion fails.  Initially 0.		*/
+			
+
+GC_API char *GC_stackbottom;	/* Cool end of user stack.		*/
+				/* May be set in the client prior to	*/
+				/* calling any GC_ routines.  This	*/
+				/* avoids some overhead, and 		*/
+				/* potentially some signals that can 	*/
+				/* confuse debuggers.  Otherwise the	*/
+				/* collector attempts to set it 	*/
+				/* automatically.			*/
+				/* For multithreaded code, this is the	*/
+				/* cold end of the stack for the	*/
+				/* primordial thread.			*/
+				
+/* Public procedures */
+/*
+ * general purpose allocation routines, with roughly malloc calling conv.
+ * The atomic versions promise that no relevant pointers are contained
+ * in the object.  The nonatomic versions guarantee that the new object
+ * is cleared.  GC_malloc_stubborn promises that no changes to the object
+ * will occur after GC_end_stubborn_change has been called on the
+ * result of GC_malloc_stubborn. GC_malloc_uncollectable allocates an object
+ * that is scanned for pointers to collectable objects, but is not itself
+ * collectable.  GC_malloc_uncollectable and GC_free called on the resulting
+ * object implicitly update GC_non_gc_bytes appropriately.
+ */
+GC_API GC_PTR GC_malloc GC_PROTO((size_t size_in_bytes));
+GC_API GC_PTR GC_malloc_atomic GC_PROTO((size_t size_in_bytes));
+GC_API GC_PTR GC_malloc_uncollectable GC_PROTO((size_t size_in_bytes));
+GC_API GC_PTR GC_malloc_stubborn GC_PROTO((size_t size_in_bytes));
+
+/* The following is only defined if the library has been suitably	*/
+/* compiled:								*/
+GC_API GC_PTR GC_malloc_atomic_uncollectable GC_PROTO((size_t size_in_bytes));
+
+/* Explicitly deallocate an object.  Dangerous if used incorrectly.     */
+/* Requires a pointer to the base of an object.				*/
+/* If the argument is stubborn, it should not be changeable when freed. */
+/* An object should not be enable for finalization when it is 		*/
+/* explicitly deallocated.						*/
+/* GC_free(0) is a no-op, as required by ANSI C for free.		*/
+GC_API void GC_free GC_PROTO((GC_PTR object_addr));
+
+/*
+ * Stubborn objects may be changed only if the collector is explicitly informed.
+ * The collector is implicitly informed of coming change when such
+ * an object is first allocated.  The following routines inform the
+ * collector that an object will no longer be changed, or that it will
+ * once again be changed.  Only nonNIL pointer stores into the object
+ * are considered to be changes.  The argument to GC_end_stubborn_change
+ * must be exacly the value returned by GC_malloc_stubborn or passed to
+ * GC_change_stubborn.  (In the second case it may be an interior pointer
+ * within 512 bytes of the beginning of the objects.)
+ * There is a performance penalty for allowing more than
+ * one stubborn object to be changed at once, but it is acceptable to
+ * do so.  The same applies to dropping stubborn objects that are still
+ * changeable.
+ */
+GC_API void GC_change_stubborn GC_PROTO((GC_PTR));
+GC_API void GC_end_stubborn_change GC_PROTO((GC_PTR));
+
+/* Return a pointer to the base (lowest address) of an object given	*/
+/* a pointer to a location within the object.				*/
+/* Return 0 if displaced_pointer doesn't point to within a valid	*/
+/* object.								*/
+GC_API GC_PTR GC_base GC_PROTO((GC_PTR displaced_pointer));
+
+/* Given a pointer to the base of an object, return its size in bytes.	*/
+/* The returned size may be slightly larger than what was originally	*/
+/* requested.								*/
+GC_API size_t GC_size GC_PROTO((GC_PTR object_addr));
+
+/* For compatibility with C library.  This is occasionally faster than	*/
+/* a malloc followed by a bcopy.  But if you rely on that, either here	*/
+/* or with the standard C library, your code is broken.  In my		*/
+/* opinion, it shouldn't have been invented, but now we're stuck. -HB	*/
+/* The resulting object has the same kind as the original.		*/
+/* If the argument is stubborn, the result will have changes enabled.	*/
+/* It is an error to have changes enabled for the original object.	*/
+/* Follows ANSI comventions for NULL old_object.			*/
+GC_API GC_PTR GC_realloc
+	GC_PROTO((GC_PTR old_object, size_t new_size_in_bytes));
+				   
+/* Explicitly increase the heap size.	*/
+/* Returns 0 on failure, 1 on success.  */
+GC_API int GC_expand_hp GC_PROTO((size_t number_of_bytes));
+
+/* Limit the heap size to n bytes.  Useful when you're debugging, 	*/
+/* especially on systems that don't handle running out of memory well.	*/
+/* n == 0 ==> unbounded.  This is the default.				*/
+GC_API void GC_set_max_heap_size GC_PROTO((GC_word n));
+
+/* Inform the collector that a certain section of statically allocated	*/
+/* memory contains no pointers to garbage collected memory.  Thus it 	*/
+/* need not be scanned.  This is sometimes important if the application */
+/* maps large read/write files into the address space, which could be	*/
+/* mistaken for dynamic library data segments on some systems.		*/
+GC_API void GC_exclude_static_roots GC_PROTO((GC_PTR start, GC_PTR finish));
+
+/* Clear the set of root segments.  Wizards only. */
+GC_API void GC_clear_roots GC_PROTO((void));
+
+/* Add a root segment.  Wizards only. */
+GC_API void GC_add_roots GC_PROTO((char * low_address,
+				   char * high_address_plus_1));
+
+/* Add a displacement to the set of those considered valid by the	*/
+/* collector.  GC_register_displacement(n) means that if p was returned */
+/* by GC_malloc, then (char *)p + n will be considered to be a valid	*/
+/* pointer to n.  N must be small and less than the size of p.		*/
+/* (All pointers to the interior of objects from the stack are		*/
+/* considered valid in any case.  This applies to heap objects and	*/
+/* static data.)							*/
+/* Preferably, this should be called before any other GC procedures.	*/
+/* Calling it later adds to the probability of excess memory		*/
+/* retention.								*/
+/* This is a no-op if the collector was compiled with recognition of	*/
+/* arbitrary interior pointers enabled, which is now the default.	*/
+GC_API void GC_register_displacement GC_PROTO((GC_word n));
+
+/* The following version should be used if any debugging allocation is	*/
+/* being done.								*/
+GC_API void GC_debug_register_displacement GC_PROTO((GC_word n));
+
+/* Explicitly trigger a full, world-stop collection. 	*/
+GC_API void GC_gcollect GC_PROTO((void));
+
+/* Trigger a full world-stopped collection.  Abort the collection if 	*/
+/* and when stop_func returns a nonzero value.  Stop_func will be 	*/
+/* called frequently, and should be reasonably fast.  This works even	*/
+/* if virtual dirty bits, and hence incremental collection is not 	*/
+/* available for this architecture.  Collections can be aborted faster	*/
+/* than normal pause times for incremental collection.  However,	*/
+/* aborted collections do no useful work; the next collection needs	*/
+/* to start from the beginning.						*/
+/* Return 0 if the collection was aborted, 1 if it succeeded.		*/
+typedef int (* GC_stop_func) GC_PROTO((void));
+GC_API int GC_try_to_collect GC_PROTO((GC_stop_func stop_func));
+
+/* Return the number of bytes in the heap.  Excludes collector private	*/
+/* data structures.  Includes empty blocks and fragmentation loss.	*/
+/* Includes some pages that were allocated but never written.		*/
+GC_API size_t GC_get_heap_size GC_PROTO((void));
+
+/* Return the number of bytes allocated since the last collection.	*/
+GC_API size_t GC_get_bytes_since_gc GC_PROTO((void));
+
+/* Enable incremental/generational collection.	*/
+/* Not advisable unless dirty bits are 		*/
+/* available or most heap objects are		*/
+/* pointerfree(atomic) or immutable.		*/
+/* Don't use in leak finding mode.		*/
+/* Ignored if GC_dont_gc is true.		*/
+GC_API void GC_enable_incremental GC_PROTO((void));
+
+/* Perform some garbage collection work, if appropriate.	*/
+/* Return 0 if there is no more work to be done.		*/
+/* Typically performs an amount of work corresponding roughly	*/
+/* to marking from one page.  May do more work if further	*/
+/* progress requires it, e.g. if incremental collection is	*/
+/* disabled.  It is reasonable to call this in a wait loop	*/
+/* until it returns 0.						*/
+GC_API int GC_collect_a_little GC_PROTO((void));
+
+/* Allocate an object of size lb bytes.  The client guarantees that	*/
+/* as long as the object is live, it will be referenced by a pointer	*/
+/* that points to somewhere within the first 256 bytes of the object.	*/
+/* (This should normally be declared volatile to prevent the compiler	*/
+/* from invalidating this assertion.)  This routine is only useful	*/
+/* if a large array is being allocated.  It reduces the chance of 	*/
+/* accidentally retaining such an array as a result of scanning an	*/
+/* integer that happens to be an address inside the array.  (Actually,	*/
+/* it reduces the chance of the allocator not finding space for such	*/
+/* an array, since it will try hard to avoid introducing such a false	*/
+/* reference.)  On a SunOS 4.X or MS Windows system this is recommended */
+/* for arrays likely to be larger than 100K or so.  For other systems,	*/
+/* or if the collector is not configured to recognize all interior	*/
+/* pointers, the threshold is normally much higher.			*/
+GC_API GC_PTR GC_malloc_ignore_off_page GC_PROTO((size_t lb));
+GC_API GC_PTR GC_malloc_atomic_ignore_off_page GC_PROTO((size_t lb));
+
+#if defined(__sgi) && !defined(__GNUC__) && _COMPILER_VERSION >= 720
+#   define GC_ADD_CALLER
+#   define GC_RETURN_ADDR (GC_word)__return_address
+#endif
+
+#ifdef GC_ADD_CALLER
+#  define GC_EXTRAS GC_RETURN_ADDR, __FILE__, __LINE__
+#  define GC_EXTRA_PARAMS GC_word ra, char * descr_string, int descr_int
+#else
+#  define GC_EXTRAS __FILE__, __LINE__
+#  define GC_EXTRA_PARAMS char * descr_string, int descr_int
+#endif
+
+/* Debugging (annotated) allocation.  GC_gcollect will check 		*/
+/* objects allocated in this way for overwrites, etc.			*/
+GC_API GC_PTR GC_debug_malloc
+	GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
+GC_API GC_PTR GC_debug_malloc_atomic
+	GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
+GC_API GC_PTR GC_debug_malloc_uncollectable
+	GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
+GC_API GC_PTR GC_debug_malloc_stubborn
+	GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
+GC_API void GC_debug_free GC_PROTO((GC_PTR object_addr));
+GC_API GC_PTR GC_debug_realloc
+	GC_PROTO((GC_PTR old_object, size_t new_size_in_bytes,
+  		  GC_EXTRA_PARAMS));
+  			 	 
+GC_API void GC_debug_change_stubborn GC_PROTO((GC_PTR));
+GC_API void GC_debug_end_stubborn_change GC_PROTO((GC_PTR));
+# ifdef GC_DEBUG
+#   define GC_MALLOC(sz) GC_debug_malloc(sz, GC_EXTRAS)
+#   define GC_MALLOC_ATOMIC(sz) GC_debug_malloc_atomic(sz, GC_EXTRAS)
+#   define GC_MALLOC_UNCOLLECTABLE(sz) GC_debug_malloc_uncollectable(sz, \
+							GC_EXTRAS)
+#   define GC_REALLOC(old, sz) GC_debug_realloc(old, sz, GC_EXTRAS)
+#   define GC_FREE(p) GC_debug_free(p)
+#   define GC_REGISTER_FINALIZER(p, f, d, of, od) \
+	GC_debug_register_finalizer(p, f, d, of, od)
+#   define GC_REGISTER_FINALIZER_IGNORE_SELF(p, f, d, of, od) \
+	GC_debug_register_finalizer_ignore_self(p, f, d, of, od)
+#   define GC_MALLOC_STUBBORN(sz) GC_debug_malloc_stubborn(sz, GC_EXTRAS);
+#   define GC_CHANGE_STUBBORN(p) GC_debug_change_stubborn(p)
+#   define GC_END_STUBBORN_CHANGE(p) GC_debug_end_stubborn_change(p)
+#   define GC_GENERAL_REGISTER_DISAPPEARING_LINK(link, obj) \
+	GC_general_register_disappearing_link(link, GC_base(obj))
+#   define GC_REGISTER_DISPLACEMENT(n) GC_debug_register_displacement(n)
+# else
+#   define GC_MALLOC(sz) GC_malloc(sz)
+#   define GC_MALLOC_ATOMIC(sz) GC_malloc_atomic(sz)
+#   define GC_MALLOC_UNCOLLECTABLE(sz) GC_malloc_uncollectable(sz)
+#   define GC_REALLOC(old, sz) GC_realloc(old, sz)
+#   define GC_FREE(p) GC_free(p)
+#   define GC_REGISTER_FINALIZER(p, f, d, of, od) \
+	GC_register_finalizer(p, f, d, of, od)
+#   define GC_REGISTER_FINALIZER_IGNORE_SELF(p, f, d, of, od) \
+	GC_register_finalizer_ignore_self(p, f, d, of, od)
+#   define GC_MALLOC_STUBBORN(sz) GC_malloc_stubborn(sz)
+#   define GC_CHANGE_STUBBORN(p) GC_change_stubborn(p)
+#   define GC_END_STUBBORN_CHANGE(p) GC_end_stubborn_change(p)
+#   define GC_GENERAL_REGISTER_DISAPPEARING_LINK(link, obj) \
+	GC_general_register_disappearing_link(link, obj)
+#   define GC_REGISTER_DISPLACEMENT(n) GC_register_displacement(n)
+# endif
+/* The following are included because they are often convenient, and	*/
+/* reduce the chance for a misspecifed size argument.  But calls may	*/
+/* expand to something syntactically incorrect if t is a complicated	*/
+/* type expression.  							*/
+# define GC_NEW(t) (t *)GC_MALLOC(sizeof (t))
+# define GC_NEW_ATOMIC(t) (t *)GC_MALLOC_ATOMIC(sizeof (t))
+# define GC_NEW_STUBBORN(t) (t *)GC_MALLOC_STUBBORN(sizeof (t))
+# define GC_NEW_UNCOLLECTABLE(t) (t *)GC_MALLOC_UNCOLLECTABLE(sizeof (t))
+
+/* Finalization.  Some of these primitives are grossly unsafe.		*/
+/* The idea is to make them both cheap, and sufficient to build		*/
+/* a safer layer, closer to PCedar finalization.			*/
+/* The interface represents my conclusions from a long discussion	*/
+/* with Alan Demers, Dan Greene, Carl Hauser, Barry Hayes, 		*/
+/* Christian Jacobi, and Russ Atkinson.  It's not perfect, and		*/
+/* probably nobody else agrees with it.	    Hans-J. Boehm  3/13/92	*/
+typedef void (*GC_finalization_proc)
+  	GC_PROTO((GC_PTR obj, GC_PTR client_data));
+
+GC_API void GC_register_finalizer
+    	GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
+		  GC_finalization_proc *ofn, GC_PTR *ocd));
+GC_API void GC_debug_register_finalizer
+    	GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
+		  GC_finalization_proc *ofn, GC_PTR *ocd));
+	/* When obj is no longer accessible, invoke		*/
+	/* (*fn)(obj, cd).  If a and b are inaccessible, and	*/
+	/* a points to b (after disappearing links have been	*/
+	/* made to disappear), then only a will be		*/
+	/* finalized.  (If this does not create any new		*/
+	/* pointers to b, then b will be finalized after the	*/
+	/* next collection.)  Any finalizable object that	*/
+	/* is reachable from itself by following one or more	*/
+	/* pointers will not be finalized (or collected).	*/
+	/* Thus cycles involving finalizable objects should	*/
+	/* be avoided, or broken by disappearing links.		*/
+	/* All but the last finalizer registered for an object  */
+	/* is ignored.						*/
+	/* Finalization may be removed by passing 0 as fn.	*/
+	/* Finalizers are implicitly unregistered just before   */
+	/* they are invoked.					*/
+	/* The old finalizer and client data are stored in	*/
+	/* *ofn and *ocd.					*/ 
+	/* Fn is never invoked on an accessible object,		*/
+	/* provided hidden pointers are converted to real 	*/
+	/* pointers only if the allocation lock is held, and	*/
+	/* such conversions are not performed by finalization	*/
+	/* routines.						*/
+	/* If GC_register_finalizer is aborted as a result of	*/
+	/* a signal, the object may be left with no		*/
+	/* finalization, even if neither the old nor new	*/
+	/* finalizer were NULL.					*/
+	/* Obj should be the nonNULL starting address of an 	*/
+	/* object allocated by GC_malloc or friends.		*/
+	/* Note that any garbage collectable object referenced	*/
+	/* by cd will be considered accessible until the	*/
+	/* finalizer is invoked.				*/
+
+/* Another versions of the above follow.  It ignores		*/
+/* self-cycles, i.e. pointers from a finalizable object to	*/
+/* itself.  There is a stylistic argument that this is wrong,	*/
+/* but it's unavoidable for C++, since the compiler may		*/
+/* silently introduce these.  It's also benign in that specific	*/
+/* case.							*/
+GC_API void GC_register_finalizer_ignore_self
+	GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
+		  GC_finalization_proc *ofn, GC_PTR *ocd));
+GC_API void GC_debug_register_finalizer_ignore_self
+	GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
+		  GC_finalization_proc *ofn, GC_PTR *ocd));
+
+/* The following routine may be used to break cycles between	*/
+/* finalizable objects, thus causing cyclic finalizable		*/
+/* objects to be finalized in the correct order.  Standard	*/
+/* use involves calling GC_register_disappearing_link(&p),	*/
+/* where p is a pointer that is not followed by finalization	*/
+/* code, and should not be considered in determining 		*/
+/* finalization order.						*/
+GC_API int GC_register_disappearing_link GC_PROTO((GC_PTR * /* link */));
+	/* Link should point to a field of a heap allocated 	*/
+	/* object obj.  *link will be cleared when obj is	*/
+	/* found to be inaccessible.  This happens BEFORE any	*/
+	/* finalization code is invoked, and BEFORE any		*/
+	/* decisions about finalization order are made.		*/
+	/* This is useful in telling the finalizer that 	*/
+	/* some pointers are not essential for proper		*/
+	/* finalization.  This may avoid finalization cycles.	*/
+	/* Note that obj may be resurrected by another		*/
+	/* finalizer, and thus the clearing of *link may	*/
+	/* be visible to non-finalization code.  		*/
+	/* There's an argument that an arbitrary action should  */
+	/* be allowed here, instead of just clearing a pointer. */
+	/* But this causes problems if that action alters, or 	*/
+	/* examines connectivity.				*/
+	/* Returns 1 if link was already registered, 0		*/
+	/* otherwise.						*/
+	/* Only exists for backward compatibility.  See below:	*/
+	
+GC_API int GC_general_register_disappearing_link
+	GC_PROTO((GC_PTR * /* link */, GC_PTR obj));
+	/* A slight generalization of the above. *link is	*/
+	/* cleared when obj first becomes inaccessible.  This	*/
+	/* can be used to implement weak pointers easily and	*/
+	/* safely. Typically link will point to a location	*/
+	/* holding a disguised pointer to obj.  (A pointer 	*/
+	/* inside an "atomic" object is effectively  		*/
+	/* disguised.)   In this way soft			*/
+	/* pointers are broken before any object		*/
+	/* reachable from them are finalized.  Each link	*/
+	/* May be registered only once, i.e. with one obj	*/
+	/* value.  This was added after a long email discussion */
+	/* with John Ellis.					*/
+	/* Obj must be a pointer to the first word of an object */
+	/* we allocated.  It is unsafe to explicitly deallocate */
+	/* the object containing link.  Explicitly deallocating */
+	/* obj may or may not cause link to eventually be	*/
+	/* cleared.						*/
+GC_API int GC_unregister_disappearing_link GC_PROTO((GC_PTR * /* link */));
+	/* Returns 0 if link was not actually registered.	*/
+	/* Undoes a registration by either of the above two	*/
+	/* routines.						*/
+
+/* Auxiliary fns to make finalization work correctly with displaced	*/
+/* pointers introduced by the debugging allocators.			*/
+GC_API GC_PTR GC_make_closure GC_PROTO((GC_finalization_proc fn, GC_PTR data));
+GC_API void GC_debug_invoke_finalizer GC_PROTO((GC_PTR obj, GC_PTR data));
+
+GC_API int GC_invoke_finalizers GC_PROTO((void));
+	/* Run finalizers for all objects that are ready to	*/
+	/* be finalized.  Return the number of finalizers	*/
+	/* that were run.  Normally this is also called		*/
+	/* implicitly during some allocations.	If		*/
+	/* GC-finalize_on_demand is nonzero, it must be called	*/
+	/* explicitly.						*/
+
+/* GC_set_warn_proc can be used to redirect or filter warning messages.	*/
+/* p may not be a NULL pointer.						*/
+typedef void (*GC_warn_proc) GC_PROTO((char *msg, GC_word arg));
+GC_API GC_warn_proc GC_set_warn_proc GC_PROTO((GC_warn_proc p));
+    /* Returns old warning procedure.	*/
+	
+/* The following is intended to be used by a higher level	*/
+/* (e.g. cedar-like) finalization facility.  It is expected	*/
+/* that finalization code will arrange for hidden pointers to	*/
+/* disappear.  Otherwise objects can be accessed after they	*/
+/* have been collected.						*/
+/* Note that putting pointers in atomic objects or in 		*/
+/* nonpointer slots of "typed" objects is equivalent to 	*/
+/* disguising them in this way, and may have other advantages.	*/
+# if defined(I_HIDE_POINTERS) || defined(GC_I_HIDE_POINTERS)
+    typedef GC_word GC_hidden_pointer;
+#   define HIDE_POINTER(p) (~(GC_hidden_pointer)(p))
+#   define REVEAL_POINTER(p) ((GC_PTR)(HIDE_POINTER(p)))
+    /* Converting a hidden pointer to a real pointer requires verifying	*/
+    /* that the object still exists.  This involves acquiring the  	*/
+    /* allocator lock to avoid a race with the collector.		*/
+# endif /* I_HIDE_POINTERS */
+
+typedef GC_PTR (*GC_fn_type) GC_PROTO((GC_PTR client_data));
+GC_API GC_PTR GC_call_with_alloc_lock
+        	GC_PROTO((GC_fn_type fn, GC_PTR client_data));
+
+/* Check that p and q point to the same object.  		*/
+/* Fail conspicuously if they don't.				*/
+/* Returns the first argument.  				*/
+/* Succeeds if neither p nor q points to the heap.		*/
+/* May succeed if both p and q point to between heap objects.	*/
+GC_API GC_PTR GC_same_obj GC_PROTO((GC_PTR p, GC_PTR q));
+
+/* Checked pointer pre- and post- increment operations.  Note that	*/
+/* the second argument is in units of bytes, not multiples of the	*/
+/* object size.  This should either be invoked from a macro, or the	*/
+/* call should be automatically generated.				*/
+GC_API GC_PTR GC_pre_incr GC_PROTO((GC_PTR *p, size_t how_much));
+GC_API GC_PTR GC_post_incr GC_PROTO((GC_PTR *p, size_t how_much));
+
+/* Check that p is visible						*/
+/* to the collector as a possibly pointer containing location.		*/
+/* If it isn't fail conspicuously.					*/
+/* Returns the argument in all cases.  May erroneously succeed		*/
+/* in hard cases.  (This is intended for debugging use with		*/
+/* untyped allocations.  The idea is that it should be possible, though	*/
+/* slow, to add such a call to all indirect pointer stores.)		*/
+/* Currently useless for multithreaded worlds.				*/
+GC_API GC_PTR GC_is_visible GC_PROTO((GC_PTR p));
+
+/* Check that if p is a pointer to a heap page, then it points to	*/
+/* a valid displacement within a heap object.				*/
+/* Fail conspicuously if this property does not hold.			*/
+/* Uninteresting with ALL_INTERIOR_POINTERS.				*/
+/* Always returns its argument.						*/
+GC_API GC_PTR GC_is_valid_displacement GC_PROTO((GC_PTR	p));
+
+/* Safer, but slow, pointer addition.  Probably useful mainly with 	*/
+/* a preprocessor.  Useful only for heap pointers.			*/
+#ifdef GC_DEBUG
+#   define GC_PTR_ADD3(x, n, type_of_result) \
+	((type_of_result)GC_same_obj((x)+(n), (x)))
+#   define GC_PRE_INCR3(x, n, type_of_result) \
+	((type_of_result)GC_pre_incr(&(x), (n)*sizeof(*x))
+#   define GC_POST_INCR2(x, type_of_result) \
+	((type_of_result)GC_post_incr(&(x), sizeof(*x))
+#   ifdef __GNUC__
+#       define GC_PTR_ADD(x, n) \
+	    GC_PTR_ADD3(x, n, typeof(x))
+#   define GC_PRE_INCR(x, n) \
+	    GC_PRE_INCR3(x, n, typeof(x))
+#   define GC_POST_INCR(x, n) \
+	    GC_POST_INCR3(x, typeof(x))
+#   else
+	/* We can't do this right without typeof, which ANSI	*/
+	/* decided was not sufficiently useful.  Repeatedly	*/
+	/* mentioning the arguments seems too dangerous to be	*/
+	/* useful.  So does not casting the result.		*/
+#   	define GC_PTR_ADD(x, n) ((x)+(n))
+#   endif
+#else	/* !GC_DEBUG */
+#   define GC_PTR_ADD3(x, n, type_of_result) ((x)+(n))
+#   define GC_PTR_ADD(x, n) ((x)+(n))
+#   define GC_PRE_INCR3(x, n, type_of_result) ((x) += (n))
+#   define GC_PRE_INCR(x, n) ((x) += (n))
+#   define GC_POST_INCR2(x, n, type_of_result) ((x)++)
+#   define GC_POST_INCR(x, n) ((x)++)
+#endif
+
+/* Safer assignment of a pointer to a nonstack location.	*/
+#ifdef GC_DEBUG
+# ifdef __STDC__
+#   define GC_PTR_STORE(p, q) \
+	(*(void **)GC_is_visible(p) = GC_is_valid_displacement(q))
+# else
+#   define GC_PTR_STORE(p, q) \
+	(*(char **)GC_is_visible(p) = GC_is_valid_displacement(q))
+# endif
+#else /* !GC_DEBUG */
+#   define GC_PTR_STORE(p, q) *((p) = (q))
+#endif
+
+/* Fynctions called to report pointer checking errors */
+GC_API void (*GC_same_obj_print_proc) GC_PROTO((GC_PTR p, GC_PTR q));
+
+GC_API void (*GC_is_valid_displacement_print_proc)
+	GC_PROTO((GC_PTR p));
+
+GC_API void (*GC_is_visible_print_proc)
+	GC_PROTO((GC_PTR p));
+
+#if defined(_SOLARIS_PTHREADS) && !defined(SOLARIS_THREADS)
+#   define SOLARIS_THREADS
+#endif
+
+#ifdef SOLARIS_THREADS
+/* We need to intercept calls to many of the threads primitives, so 	*/
+/* that we can locate thread stacks and stop the world.			*/
+/* Note also that the collector cannot see thread specific data.	*/
+/* Thread specific data should generally consist of pointers to		*/
+/* uncollectable objects, which are deallocated using the destructor	*/
+/* facility in thr_keycreate.						*/
+# include <thread.h>
+# include <signal.h>
+  int GC_thr_create(void *stack_base, size_t stack_size,
+                    void *(*start_routine)(void *), void *arg, long flags,
+                    thread_t *new_thread);
+  int GC_thr_join(thread_t wait_for, thread_t *departed, void **status);
+  int GC_thr_suspend(thread_t target_thread);
+  int GC_thr_continue(thread_t target_thread);
+  void * GC_dlopen(const char *path, int mode);
+
+# ifdef _SOLARIS_PTHREADS
+#   include <pthread.h>
+    extern int GC_pthread_create(pthread_t *new_thread,
+    			         const pthread_attr_t *attr,
+          			 void * (*thread_execp)(void *), void *arg);
+    extern int GC_pthread_join(pthread_t wait_for, void **status);
+
+#   undef thread_t
+
+#   define pthread_join GC_pthread_join
+#   define pthread_create GC_pthread_create
+#endif
+
+# define thr_create GC_thr_create
+# define thr_join GC_thr_join
+# define thr_suspend GC_thr_suspend
+# define thr_continue GC_thr_continue
+# define dlopen GC_dlopen
+
+# endif /* SOLARIS_THREADS */
+
+
+#if defined(IRIX_THREADS) || defined(LINUX_THREADS)
+/* We treat these similarly. */
+# include <pthread.h>
+# include <signal.h>
+
+  int GC_pthread_create(pthread_t *new_thread,
+                        const pthread_attr_t *attr,
+		        void *(*start_routine)(void *), void *arg);
+  int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset);
+  int GC_pthread_join(pthread_t thread, void **retval);
+
+# define pthread_create GC_pthread_create
+# define pthread_sigmask GC_pthread_sigmask
+# define pthread_join GC_pthread_join
+
+#endif /* IRIX_THREADS || LINUX_THREADS */
+
+# if defined(PCR) || defined(SOLARIS_THREADS) || defined(WIN32_THREADS) || \
+	defined(IRIX_THREADS) || defined(LINUX_THREADS) || \
+	defined(IRIX_JDK_THREADS)
+   	/* Any flavor of threads except SRC_M3.	*/
+/* This returns a list of objects, linked through their first		*/
+/* word.  Its use can greatly reduce lock contention problems, since	*/
+/* the allocation lock can be acquired and released many fewer times.	*/
+/* lb must be large enough to hold the pointer field.			*/
+GC_PTR GC_malloc_many(size_t lb);
+#define GC_NEXT(p) (*(GC_PTR *)(p)) 	/* Retrieve the next element	*/
+					/* in returned list.		*/
+extern void GC_thr_init();	/* Needed for Solaris/X86	*/
+
+#endif /* THREADS && !SRC_M3 */
+
+/*
+ * If you are planning on putting
+ * the collector in a SunOS 5 dynamic library, you need to call GC_INIT()
+ * from the statically loaded program section.
+ * This circumvents a Solaris 2.X (X<=4) linker bug.
+ */
+#if defined(sparc) || defined(__sparc)
+#   define GC_INIT() { extern end, etext; \
+		       GC_noop(&end, &etext); }
+#else
+# if defined(__CYGWIN32__) && defined(GC_USE_DLL)
+    /*
+     * Similarly gnu-win32 DLLs need explicit initialization
+     */
+#   define GC_INIT() { GC_add_roots(DATASTART, DATAEND); }
+# else
+#   define GC_INIT()
+# endif
+#endif
+
+#if (defined(_MSDOS) || defined(_MSC_VER)) && (_M_IX86 >= 300) \
+     || defined(_WIN32)
+  /* win32S may not free all resources on process exit.  */
+  /* This explicitly deallocates the heap.		 */
+    GC_API void GC_win32_free_heap ();
+#endif
+
+#ifdef __cplusplus
+    }  /* end of extern "C" */
+#endif
+
+#endif /* _GC_H */