Merge tag 'gc6_0' into ancient-releases

23 files changed, 440 insertions, 201 deletions

diff --git a/Makefile b/Makefile
index e2df4529..a5d24c65 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-# This is the original manually generated Makefile.  It may stil be used
+# This is the original manually generated Makefile.  It may still be used
 # to build the collector.
 #
 # Primary targets:
@@ -88,10 +88,11 @@ HOSTCFLAGS=$(CFLAGS)
 #   code from the heap.  Currently this only affects the incremental
 #   collector on UNIX machines.  It may greatly improve its performance,
 #   since this may avoid some expensive cache synchronization.
-# -DOPERATOR_NEW_ARRAY declares that the C++ compiler supports the
-#   new syntax "operator new[]" for allocating and deleting arrays.
+# -DGC_NO_OPERATOR_NEW_ARRAY declares that the C++ compiler does not support
+#   the  new syntax "operator new[]" for allocating and deleting arrays.
 #   See gc_cpp.h for details.  No effect on the C part of the collector.
-#   This is defined implicitly in a few environments.
+#   This is defined implicitly in a few environments.  Must also be defined
+#   by clients that use gc_cpp.h.
 # -DREDIRECT_MALLOC=X causes malloc, realloc, and free to be defined
 #   as aliases for X, GC_realloc, and GC_free, respectively.
 #   Calloc is redefined in terms of the new malloc.  X should
@@ -250,7 +251,7 @@ DOC_FILES= README.QUICK doc/README.Mac doc/README.MacOSX doc/README.OS2 \
 	doc/README.win32 doc/barrett_diagram doc/README \
         doc/README.contributors doc/README.changes doc/gc.man \
 	doc/README.environment doc/tree.html doc/gcdescr.html \
-	doc/README.autoconf
+	doc/README.autoconf doc/README.macros
 
 TESTS= tests/test.c tests/test_cpp.cc tests/trace_test.c \
 	tests/leak_test.c tests/thread_leak_test.c
@@ -516,7 +517,7 @@ KandRtest: setjmp_test gctest
 	./setjmp_test
 	./gctest
 
-add_gc_prefix: $(srcdir)/add_gc_prefix.c
+add_gc_prefix: $(srcdir)/add_gc_prefix.c $(srcdir)/version.h
 	$(CC) -o add_gc_prefix $(srcdir)/add_gc_prefix.c
 
 gcname: $(srcdir)/gcname.c $(srcdir)/version.h
diff --git a/Makefile.direct b/Makefile.direct
index e2df4529..a5d24c65 100644
--- a/Makefile.direct
+++ b/Makefile.direct
@@ -1,4 +1,4 @@
-# This is the original manually generated Makefile.  It may stil be used
+# This is the original manually generated Makefile.  It may still be used
 # to build the collector.
 #
 # Primary targets:
@@ -88,10 +88,11 @@ HOSTCFLAGS=$(CFLAGS)
 #   code from the heap.  Currently this only affects the incremental
 #   collector on UNIX machines.  It may greatly improve its performance,
 #   since this may avoid some expensive cache synchronization.
-# -DOPERATOR_NEW_ARRAY declares that the C++ compiler supports the
-#   new syntax "operator new[]" for allocating and deleting arrays.
+# -DGC_NO_OPERATOR_NEW_ARRAY declares that the C++ compiler does not support
+#   the  new syntax "operator new[]" for allocating and deleting arrays.
 #   See gc_cpp.h for details.  No effect on the C part of the collector.
-#   This is defined implicitly in a few environments.
+#   This is defined implicitly in a few environments.  Must also be defined
+#   by clients that use gc_cpp.h.
 # -DREDIRECT_MALLOC=X causes malloc, realloc, and free to be defined
 #   as aliases for X, GC_realloc, and GC_free, respectively.
 #   Calloc is redefined in terms of the new malloc.  X should
@@ -250,7 +251,7 @@ DOC_FILES= README.QUICK doc/README.Mac doc/README.MacOSX doc/README.OS2 \
 	doc/README.win32 doc/barrett_diagram doc/README \
         doc/README.contributors doc/README.changes doc/gc.man \
 	doc/README.environment doc/tree.html doc/gcdescr.html \
-	doc/README.autoconf
+	doc/README.autoconf doc/README.macros
 
 TESTS= tests/test.c tests/test_cpp.cc tests/trace_test.c \
 	tests/leak_test.c tests/thread_leak_test.c
@@ -516,7 +517,7 @@ KandRtest: setjmp_test gctest
 	./setjmp_test
 	./gctest
 
-add_gc_prefix: $(srcdir)/add_gc_prefix.c
+add_gc_prefix: $(srcdir)/add_gc_prefix.c $(srcdir)/version.h
 	$(CC) -o add_gc_prefix $(srcdir)/add_gc_prefix.c
 
 gcname: $(srcdir)/gcname.c $(srcdir)/version.h
diff --git a/Makefile.dj b/Makefile.dj
index 26434492..09fae4e6 100644
--- a/Makefile.dj
+++ b/Makefile.dj
@@ -62,10 +62,11 @@ CFLAGS= -O -I$(srcdir)/include -DATOMIC_UNCOLLECTABLE -DNO_SIGNALS -DALL_INTERIO
 #   code from the heap.  Currently this only affects the incremental
 #   collector on UNIX machines.  It may greatly improve its performance,
 #   since this may avoid some expensive cache synchronization.
-# -DOPERATOR_NEW_ARRAY declares that the C++ compiler supports the
-#   new syntax "operator new[]" for allocating and deleting arrays.
+# -DGC_NO_OPERATOR_NEW_ARRAY declares that the C++ compiler does not support
+#   the  new syntax "operator new[]" for allocating and deleting arrays.
 #   See gc_cpp.h for details.  No effect on the C part of the collector.
-#   This is defined implicitly in a few environments.
+#   This is defined implicitly in a few environments.  Must also be defined
+#   by clients that use gc_cpp.h.
 # -DREDIRECT_MALLOC=X causes malloc, realloc, and free to be defined
 #   as aliases for X, GC_realloc, and GC_free, respectively.
 #   Calloc is redefined in terms of the new malloc.  X should
diff --git a/alpha_mach_dep.s b/alpha_mach_dep.s
index 783ebf1f..53547307 100644
--- a/alpha_mach_dep.s
+++ b/alpha_mach_dep.s
@@ -1,64 +1,87 @@
  # $Id: alpha_mach_dep.s,v 1.2 1993/01/18 22:54:51 dosser Exp $
+	.arch ev6
 
-# This is BROKEN on a 21264 running gcc, and probably in other cases.
-# The compiler may spill pointers to fp registers, and this code doesn't
-# scan those.
-
-# define call_push(x)    						\
-	lda   $16, 0(x);    	/* copy x to first argument register */	\
-	jsr   $26, GC_push_one; /* call GC_push_one, ret addr in $26 */	\
-	ldgp  $gp, 0($26)	/* restore $gp register from $ra */
-	
         .text
         .align  4
         .globl  GC_push_regs
         .ent    GC_push_regs 2
 GC_push_regs:
-	ldgp    $gp, 0($27)		# set gp from the procedure value reg
-	lda     $sp, -32($sp)		# make stack frame
-	stq     $26, 8($sp)		# save return address
-        .mask   0x04000000, -8
+	ldgp    $gp, 0($27)
+	lda     $sp, -16($sp)
+	stq     $26, 0($sp)
+        .mask   0x04000000, 0
         .frame  $sp, 16, $26, 0
 
- #      call_push($0)    # expression eval and int func result
-
- #      call_push($1)    # temp regs - not preserved cross calls
- #      call_push($2)
- #      call_push($3)
- #      call_push($4)
- #      call_push($5)
- #      call_push($6)
- #      call_push($7)
- #      call_push($8)
+ # $0		integer result
+ # $1-$8	temp regs - not preserved cross calls
+ # $9-$15	call saved regs
+ # $16-$21	argument regs - not preserved cross calls
+ # $22-$28	temp regs - not preserved cross calls
+ # $29		global pointer - not preserved cross calls
+ # $30		stack pointer
 
-        call_push($9)    # Saved regs
+# define call_push(x)			\
+	mov   x, $16;			\
+	jsr   $26, GC_push_one;		\
+	ldgp  $gp, 0($26)
+	
+        call_push($9)
         call_push($10)
         call_push($11)
         call_push($12)
         call_push($13)
         call_push($14)
+        call_push($15)
+
+ # $f0-$f1	floating point results
+ # $f2-$f9	call saved regs
+ # $f10-$f30	temp regs - not preserved cross calls
+
+	# Use the most efficient transfer method for this hardware.
+	# Bit 1 detects the FIX extension, which includes ftoit.
+	amask	2, $0
+	bne	$0, $use_stack
+
+#undef call_push
+#define call_push(x)			\
+	ftoit	x, $16;			\
+	jsr	$26, GC_push_one;	\
+	ldgp	$gp, 0($26)
+
+	call_push($f2)
+	call_push($f3)
+	call_push($f4)
+	call_push($f5)
+	call_push($f6)
+	call_push($f7)
+	call_push($f8)
+	call_push($f9)
+
+	ldq     $26, 0($sp)
+	lda     $sp, 16($sp)
+	ret     $31, ($26), 1
 
-        call_push($15)   # frame ptr or saved reg
+	.align	4
+$use_stack:
 
- #      call_push($16)   # argument regs - not preserved cross calls
- #      call_push($17)
- #      call_push($18)
- #      call_push($19)
- #      call_push($20)
- #      call_push($21)
+#undef call_push
+#define call_push(x)			\
+	stt	x, 8($sp);		\
+	ldq	$16, 8($sp);		\
+	jsr	$26, GC_push_one;	\
+	ldgp	$gp, 0($26)
 
- #      call_push($22)   # temp regs - not preserved cross calls
- #      call_push($23)
- #      call_push($24)
- #      call_push($25)
+	call_push($f2)
+	call_push($f3)
+	call_push($f4)
+	call_push($f5)
+	call_push($f6)
+	call_push($f7)
+	call_push($f8)
+	call_push($f9)
 
- #      call_push($26)   # return address - expression eval
- #      call_push($27)   # procedure value or temporary reg
- #      call_push($28)   # assembler temp - not presrved
-        call_push($29)   # Global Pointer
- #      call_push($30)   # Stack Pointer
+	ldq     $26, 0($sp)
+	lda     $sp, 16($sp)
+	ret     $31, ($26), 1
 
-	ldq     $26, 8($sp)		# restore return address
-	lda     $sp, 32($sp)		# pop stack frame
-	ret     $31, ($26), 1		# return ($31 == hardwired zero)
 	.end    GC_push_regs
diff --git a/configure b/configure
index 8fba7d59..1146ce66 100755
--- a/configure
+++ b/configure
@@ -2192,6 +2192,16 @@ EOF
 EOF
 
 	;;
+     *-*-linux*)
+	cat >> confdefs.h <<\EOF
+#define GC_LINUX_THREADS 1
+EOF
+
+	cat >> confdefs.h <<\EOF
+#define _REENTRANT 1
+EOF
+
+	;;
      *-*-hpux*)
 	echo "configure: warning: "Only HP/UX 11 threads are supported."" 1>&2
 	cat >> confdefs.h <<\EOF
@@ -2214,16 +2224,6 @@ EOF
 
 	THREADLIBS="-lpthread -lrt"
 	;;
-     *-*-linux*)
-	cat >> confdefs.h <<\EOF
-#define GC_LINUX_THREADS 1
-EOF
-
-	cat >> confdefs.h <<\EOF
-#define _REENTRANT 1
-EOF
-
-	;;
      *-*-freebsd*)
 	echo "configure: warning: "FreeBSD does not yet fully support threads with Boehm GC."" 1>&2
 	cat >> confdefs.h <<\EOF
diff --git a/configure.in b/configure.in
index 0d8cf68a..fa3f81ac 100644
--- a/configure.in
+++ b/configure.in
@@ -80,6 +80,10 @@ case "$THREADS" in
 	fi
 	AC_DEFINE(THREAD_LOCAL_ALLOC)
 	;;
+     *-*-linux*)
+	AC_DEFINE(GC_LINUX_THREADS)
+	AC_DEFINE(_REENTRANT)
+	;;
      *-*-hpux*)
 	AC_MSG_WARN("Only HP/UX 11 threads are supported.")
 	AC_DEFINE(GC_HPUX_THREADS)
@@ -90,10 +94,6 @@ case "$THREADS" in
 	AC_DEFINE(THREAD_LOCAL_ALLOC)
 	THREADLIBS="-lpthread -lrt"
 	;;
-     *-*-linux*)
-	AC_DEFINE(GC_LINUX_THREADS)
-	AC_DEFINE(_REENTRANT)
-	;;
      *-*-freebsd*)
 	AC_MSG_WARN("FreeBSD does not yet fully support threads with Boehm GC.")
 	AC_DEFINE(FREEBSD_THREADS)
diff --git a/dbg_mlc.c b/dbg_mlc.c
index f6d0dde7..be3da8e2 100644
--- a/dbg_mlc.c
+++ b/dbg_mlc.c
@@ -273,7 +273,7 @@ word integer;
     /* But that's expensive.  And this way things should only appear	*/
     /* inconsistent while we're in the handler.				*/
 #   ifdef KEEP_BACK_PTRS
-      ((oh *)p) -> oh_back_ptr = 0;
+      ((oh *)p) -> oh_back_ptr = HIDE_BACK_PTR(NOT_MARKED);
 #   endif
     ((oh *)p) -> oh_string = string;
     ((oh *)p) -> oh_int = integer;
diff --git a/doc/README b/doc/README
index 1cff6e6c..c6b48c3b 100644
--- a/doc/README
+++ b/doc/README
@@ -27,7 +27,7 @@ are GPL'ed, but with an exception that should cover all uses in the
 collector.  (If you are concerned about such things, I recommend you look
 at the notice in config.guess or ltmain.sh.)
 
-This is version 6.0alpha8 of a conservative garbage collector for C and C++.
+This is version 6.0 of a conservative garbage collector for C and C++.
 
 You might find a more recent version of this at
 
diff --git a/doc/README.changes b/doc/README.changes
index a058d359..c018c8b6 100644
--- a/doc/README.changes
+++ b/doc/README.changes
@@ -1349,9 +1349,41 @@ Since 6.0alpha7:
    (Thanks to Maarten Thibaut.)
  - Fixed up the GNU-style build files enough so that they work in some
    obvious cases.
+ - Added initial port to Digital Mars compiler for win32. (Thanks to Walter
+   Bright.)
+
+Since 6.0alpha8:
+ - added README.macros.
+ - Made gc.mak a symbolic link to work around winzip's tendency to ignore
+   hard links.
+ - Simplified the setting of NEED_FIND_LIMIT in os_dep.c, possibly breaking
+   it on untested platforms.
+ - Integrated initial GNU HURD port. (Thanks to Chris Lingard and Igor
+   Khavkine.)
+ - A few more fixes for Digital Mars compiler.
+ - Fixed gcc version recognition.  Renamed OPERATOR_NEW_ARRAY to
+   GC_OPERATOR_NEW_ARRAY.  Changed GC_OPERATOR_NEW_ARRAY to be the default.
+   It can be overridden with -DGC_NO_OPERATOR_NEW_ARRAY.  (Thanks to
+   Cesar Eduardo Barros.) 
+ - Changed the byte size to free-list mapping in thread local allocation
+   so that size 0 allocations are handled correctly.
+ - Fixed Linux/MIPS stackbottom for new toolchain. (Thanks to Ryan Murray.)
+ - Changed finalization registration to invoke GC_oom_fn when it runs out
+   of memory.
+ - Removed lvalue cast in finalize.c.  This caused some debug configurations
+   not to build with some non-gcc compilers.
+
+Since 6.0alpha9:
+ - Two more bug fixes for KEEP_BACK_PTRS and DBG_HDRS_ALL.
+ - Fixed a stack clearing problem that resulted in SIGILL with a
+   misaligned stack pointer for multithreaded SPARC builds.
+ - Integrated another HURD patch (thanks to Igor Khavkine).
  
 
 To do:
+ - There seem to be outstanding issues on Solaris/X86, possibly with
+   finding the data segment starting address.  Information/patches would
+   ne appreciated.
  - New_gc_alloc.h is apparently no longer compatible with the latest C++
    standard library in gcc3.0.  (This isn't technically a bug, since it only
    claimed compatibility with the SGI STL.  But we may need a new C++ STL
diff --git a/doc/README.macros b/doc/README.macros
new file mode 100644
index 00000000..d9df8dd3
--- /dev/null
+++ b/doc/README.macros
@@ -0,0 +1,78 @@
+The collector uses a large amount of conditional compilation in order to
+deal with platform dependencies.  This violates a number of known coding
+standards.  On the other hand, it seems to be the only practical way to
+support this many platforms without excessive code duplication. 
+
+A few guidelines have mostly been followed in order to keep this manageable:
+
+1) #if and #ifdef directives are properly indented whenever easily possible.
+All known C compilers allow whitespace between the "#" and the "if" to make
+this possible.  ANSI C also allows white space before the "#", though we
+avoid that.  It has the known disadvantages that it differs from the normal
+GNU conventions, and that it makes patches larger than otherwise necessary.
+In my opinion, it's still well worth it, for the same reason that we indent
+ordinary "if" statements.
+
+2) Whenever possible, tests are performed on the macros defined in gcconfig.h
+instead of directly testing patform-specific predefined macros.  This makes it
+relatively easy to adapt to new compilers with a different set of predefined
+macros.  Currently these macros generally identify platforms instead of
+features.  In many cases, this is a mistake.
+
+3) The code currently avoids #elif, eventhough that would make it more
+readable.  This was done since #elif would need to be understood by ALL
+compilers used to build the collector, and that hasn't always been the case.
+It makes sense to reconsider this decision at some point, since #elif has been
+standardized at least since 1989.
+
+Many of the tested configuration macros are at least somewhat defined in
+either include/private/gcconfig.h or in Makefile.direct.  Here is an attempt
+at defining some of the remainder:  (Thanks to Walter Bright for suggesting
+this.  This is a work in progress)
+
+MACRO		EXPLANATION
+-----		-----------
+
+__DMC__	Always #define'd by the Digital Mars compiler. Expands
+		to the compiler version number in hex, i.e. 0x810 is
+		version 8.1b0
+
+_ENABLE_ARRAYNEW
+		#define'd by the Digital Mars C++ compiler when
+		operator new[] and delete[] are separately
+		overloadable. Used in gc_cpp.h.
+
+_MSC_VER	Expands to the Visual C++ compiler version.  Assumed to
+		not be defined for other compilers (at least if they behave
+		appreciably differently).
+
+_DLL		Defined by Visual C++ if dynamic libraries are being built
+		or used.  Used to test whether __declspec(dllimport) or
+		__declspec(dllexport) needs to be added to declarations
+		to support the case in which the collector is in a dll.
+
+GC_DLL		User-settable macro that forces the effect of _DLL.
+
+GC_NOT_DLL	User-settable macro that overrides _DLL, e.g. if dynamic
+		libraries are used, but the collector is in a static library.
+
+__STDC__	Assumed to be defined only by compilers that understand
+		prototypes and other C89 features.  Its value is generally
+		not used, since we are fine with most nonconforming extensions.
+
+SUNOS5SIGS	Solaris-like signal handling.  This is probably misnamed,
+		since it really doesn't guarantee much more than Posix.
+		Currently set only for Solaris2.X, HPUX, and DRSNX.  Should
+		probably be set for some other platforms.
+
+PCR		Set if the collector is being built as part of the Xerox
+		Portable Common Runtime.
+
+SRC_M3		Set if the collector is being built as a replacement of the
+		one in the DEC/Compaq SRC Modula-3 runtime.  I suspect this
+		was last used around 1994, and no doubt broke a long time ago.
+		It's there primarily incase someone wants to port to a similar
+		system.
+
+
+
diff --git a/dyn_load.c b/dyn_load.c
index 2fa84c91..5a86cf6c 100644
--- a/dyn_load.c
+++ b/dyn_load.c
@@ -53,7 +53,7 @@
     !(defined(ALPHA) && defined(OSF1)) && \
     !defined(HPUX) && !(defined(LINUX) && defined(__ELF__)) && \
     !defined(RS6000) && !defined(SCO_ELF) && \
-    !(defined(NETBSD) && defined(__ELF__))
+    !(defined(NETBSD) && defined(__ELF__)) && !defined(HURD)
  --> We only know how to find data segments of dynamic libraries for the
  --> above.  Additional SVR4 variants might not be too
  --> hard to add.
@@ -243,7 +243,7 @@ void GC_register_dynamic_libraries()
 # endif /* SUNOS */
 
 #if defined(LINUX) && defined(__ELF__) || defined(SCO_ELF) || \
-    (defined(NETBSD) && defined(__ELF__))
+    (defined(NETBSD) && defined(__ELF__)) || defined(HURD)
 
 
 #ifdef USE_PROC_FOR_LIBRARIES
diff --git a/finalize.c b/finalize.c
index 4c41eb54..229d8286 100644
--- a/finalize.c
+++ b/finalize.c
@@ -202,15 +202,27 @@ signed_word * log_size_ptr;
     }
     new_dl = (struct disappearing_link *)
     	GC_INTERNAL_MALLOC(sizeof(struct disappearing_link),NORMAL);
-    if (new_dl != 0) {
-        new_dl -> dl_hidden_obj = HIDE_POINTER(obj);
-        new_dl -> dl_hidden_link = HIDE_POINTER(link);
-        dl_set_next(new_dl, dl_head[index]);
-        dl_head[index] = new_dl;
-        GC_dl_entries++;
-    } else {
-        GC_finalization_failures++;
+    if (0 == new_dl) {
+#     ifdef THREADS
+	UNLOCK();
+    	ENABLE_SIGNALS();
+#     endif
+      new_dl == GC_oom_fn(sizeof(struct disappearing_link));
+      if (0 == new_dl) {
+	GC_finalization_failures++;
+	return(0);
+      }
+      /* It's not likely we'll make it here, but ... */
+#     ifdef THREADS
+        DISABLE_SIGNALS();
+	LOCK();
+#     endif
     }
+    new_dl -> dl_hidden_obj = HIDE_POINTER(obj);
+    new_dl -> dl_hidden_link = HIDE_POINTER(link);
+    dl_set_next(new_dl, dl_head[index]);
+    dl_head[index] = new_dl;
+    GC_dl_entries++;
 #   ifdef THREADS
         UNLOCK();
         ENABLE_SIGNALS();
@@ -245,7 +257,7 @@ signed_word * log_size_ptr;
             UNLOCK();
     	    ENABLE_SIGNALS();
 #	    ifdef DBG_HDRS_ALL
-	      dl_next(curr_dl) = 0;
+	      dl_set_next(curr_dl, 0);
 #	    else
               GC_free((GC_PTR)curr_dl);
 #	    endif
@@ -416,18 +428,30 @@ finalization_mark_proc * mp;
     }
     new_fo = (struct finalizable_object *)
     	GC_INTERNAL_MALLOC(sizeof(struct finalizable_object),NORMAL);
-    if (new_fo != 0) {
-        new_fo -> fo_hidden_base = (word)HIDE_POINTER(base);
-	new_fo -> fo_fn = fn;
-	new_fo -> fo_client_data = (ptr_t)cd;
-	new_fo -> fo_object_size = hhdr -> hb_sz;
-	new_fo -> fo_mark_proc = mp;
-	fo_set_next(new_fo, fo_head[index]);
-	GC_fo_entries++;
-	fo_head[index] = new_fo;
-    } else {
-     	GC_finalization_failures++;
+    if (0 == new_fo) {
+#     ifdef THREADS
+	UNLOCK();
+    	ENABLE_SIGNALS();
+#     endif
+      new_fo == GC_oom_fn(sizeof(struct finalizable_object));
+      if (0 == new_fo) {
+	GC_finalization_failures++;
+	return;
+      }
+      /* It's not likely we'll make it here, but ... */
+#     ifdef THREADS
+        DISABLE_SIGNALS();
+	LOCK();
+#     endif
     }
+    new_fo -> fo_hidden_base = (word)HIDE_POINTER(base);
+    new_fo -> fo_fn = fn;
+    new_fo -> fo_client_data = (ptr_t)cd;
+    new_fo -> fo_object_size = hhdr -> hb_sz;
+    new_fo -> fo_mark_proc = mp;
+    fo_set_next(new_fo, fo_head[index]);
+    GC_fo_entries++;
+    fo_head[index] = new_fo;
 #   ifdef THREADS
         UNLOCK();
     	ENABLE_SIGNALS();
@@ -593,7 +617,7 @@ void GC_finalize()
               GC_words_finalized +=
                  	ALIGNED_WORDS(curr_fo -> fo_object_size)
               		+ ALIGNED_WORDS(sizeof(struct finalizable_object));
-	    GC_ASSERT(GC_is_marked((ptr_t)curr_fo));
+	    GC_ASSERT(GC_is_marked(GC_base((ptr_t)curr_fo)));
             curr_fo = next_fo;
         } else {
             prev_fo = curr_fo;
diff --git a/include/gc.h b/include/gc.h
index 08952566..aaf29ee3 100644
--- a/include/gc.h
+++ b/include/gc.h
@@ -80,10 +80,6 @@
     typedef long ptrdiff_t;	/* ptrdiff_t is not defined */
 # endif
 
-#if defined(__CYGWIN32__) && defined(GC_USE_DLL)
-#include "libgc_globals.h"
-#endif
-
 #if defined(__MINGW32__) && defined(WIN32_THREADS)
 # ifdef GC_BUILD
 #   define GC_API __declspec(dllexport)
@@ -93,7 +89,7 @@
 #endif
 
 #if (defined(__DMC__) || defined(_MSC_VER)) \
-		&& (defined(_DLL) && !defined(NOT_GC_DLL) \
+		&& (defined(_DLL) && !defined(GC_NOT_DLL) \
 	            || defined(GC_DLL))
 # ifdef GC_BUILD
 #   define GC_API extern __declspec(dllexport)
@@ -348,6 +344,10 @@ 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.				*/
+/* I.e. map an interior pointer to the corresponding bas pointer.	*/
+/* Note that with debugging allocation, this returns a pointer to the	*/
+/* actual base of the object, i.e. the debug information, not to	*/
+/* the base of the user 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));
diff --git a/include/gc_cpp.h b/include/gc_cpp.h
index a0f566f7..ceb73f50 100644
--- a/include/gc_cpp.h
+++ b/include/gc_cpp.h
@@ -83,7 +83,7 @@ Cautions:
 1. Be sure the collector has been augmented with "make c++".
 
 2.  If your compiler supports the new "operator new[]" syntax, then
-add -DOPERATOR_NEW_ARRAY to the Makefile.
+add -DGC_OPERATOR_NEW_ARRAY to the Makefile.
 
 If your compiler doesn't support "operator new[]", beware that an
 array of type T, where T is derived from "gc", may or may not be
@@ -137,10 +137,17 @@ by UseGC.  GC is an alias for UseGC, unless GC_NAME_CONFLICT is defined.
 #define _cdecl
 #endif
 
-#if ! defined( OPERATOR_NEW_ARRAY ) \
-    && (__BORLANDC__ >= 0x450 || (__GNUC__ >= 2 && __GNUC_MINOR__ >= 6) \
-	|| __WATCOMC__ >= 1050 || _MSC_VER >= 1100 || _ENABLE_ARRAYNEW)
-#   define OPERATOR_NEW_ARRAY
+#if ! defined( GC_NO_OPERATOR_NEW_ARRAY ) \
+    && !defined(_ENABLE_ARRAYNEW) /* Digimars */ \
+    && (defined(__BORLANDC__) && (__BORLANDC__ < 0x450) \
+	|| (defined(__GNUC__) && \
+	    (__GNUC__ < 2 || __GNUC__ == 2 && __GNUC_MINOR__ < 6)) \
+	|| (defined(__WATCOMC__) && __WATCOMC__ < 1050))
+#   define GC_NO_OPERATOR_NEW_ARRAY
+#endif
+
+#if !defined(GC_NO_OPERATOR_NEW_ARRAY) && !defined(GC_OPERATOR_NEW_ARRAY)
+#   define GC_OPERATOR_NEW_ARRAY
 #endif
 
 enum GCPlacement {UseGC,
@@ -154,11 +161,11 @@ class gc {public:
     inline void* operator new( size_t size, GCPlacement gcp );
     inline void operator delete( void* obj );
 
-#ifdef OPERATOR_NEW_ARRAY
+#ifdef GC_OPERATOR_NEW_ARRAY
     inline void* operator new[]( size_t size );
     inline void* operator new[]( size_t size, GCPlacement gcp );
     inline void operator delete[]( void* obj );
-#endif /* OPERATOR_NEW_ARRAY */
+#endif /* GC_OPERATOR_NEW_ARRAY */
     };    
     /*
     Instances of classes derived from "gc" will be allocated in the 
@@ -204,7 +211,7 @@ inline void* operator new(
     classes derived from "gc_cleanup" or containing members derived
     from "gc_cleanup". */
 
-#ifdef OPERATOR_NEW_ARRAY
+#ifdef GC_OPERATOR_NEW_ARRAY
 
 #ifdef _MSC_VER
  /** This ensures that the system default operator new[] doesn't get
@@ -257,7 +264,7 @@ inline void* operator new[](
     /*
     The operator new for arrays, identical to the above. */
 
-#endif /* OPERATOR_NEW_ARRAY */
+#endif /* GC_OPERATOR_NEW_ARRAY */
 
 /****************************************************************************
 
@@ -280,7 +287,7 @@ inline void gc::operator delete( void* obj ) {
     GC_FREE( obj );}
     
 
-#ifdef OPERATOR_NEW_ARRAY
+#ifdef GC_OPERATOR_NEW_ARRAY
 
 inline void* gc::operator new[]( size_t size ) {
     return gc::operator new( size );}
@@ -291,7 +298,7 @@ inline void* gc::operator new[]( size_t size, GCPlacement gcp ) {
 inline void gc::operator delete[]( void* obj ) {
     gc::operator delete( obj );}
     
-#endif /* OPERATOR_NEW_ARRAY */
+#endif /* GC_OPERATOR_NEW_ARRAY */
 
 
 inline gc_cleanup::~gc_cleanup() {
@@ -332,7 +339,7 @@ inline void* operator new(
     return obj;}
         
 
-#ifdef OPERATOR_NEW_ARRAY
+#ifdef GC_OPERATOR_NEW_ARRAY
 
 inline void* operator new[]( 
     size_t size, 
@@ -342,7 +349,7 @@ inline void* operator new[](
 {
     return ::operator new( size, gcp, cleanup, clientData );}
 
-#endif /* OPERATOR_NEW_ARRAY */
+#endif /* GC_OPERATOR_NEW_ARRAY */
 
 
 #endif /* GC_CPP_H */
diff --git a/include/private/dbg_mlc.h b/include/private/dbg_mlc.h
index 6932a82d..6f5b3c86 100644
--- a/include/private/dbg_mlc.h
+++ b/include/private/dbg_mlc.h
@@ -19,7 +19,7 @@
  * not use it.  Clients that define their own object kinds with
  * debugging allocators will probably want to include this, however.
  * No attempt is made to keep the namespace clean.  This should not be
- * included from header filrd that are frequently included by clients.
+ * included from header files that are frequently included by clients.
  */
 
 #ifndef _DBG_MLC_H
@@ -68,6 +68,9 @@ typedef struct {
 	    /* overwrite a value with the least significant	*/
 	    /* bit clear, thus ensuring that we never overwrite	*/
 	    /* a free list link field.				*/
+ 	    /* Note that blocks dropped by black-listing will	*/
+ 	    /* also have the lsb clear once debugging has	*/
+ 	    /* started.						*/
 	    /* The following are special back pointer values.	*/
 	    /* Note that the "hidden" (i.e. bitwise 		*/
 	    /* complemented version) of these is actually 	*/
diff --git a/include/private/gc_priv.h b/include/private/gc_priv.h
index bc1dbea8..5135e3e9 100644
--- a/include/private/gc_priv.h
+++ b/include/private/gc_priv.h
@@ -634,7 +634,7 @@ extern GC_warn_proc GC_current_warn_proc;
 # else
 #       define ALIGNED_WORDS(n) ROUNDED_UP_WORDS(n)
 # endif
-# define SMALL_OBJ(bytes) ((bytes) < (MAXOBJBYTES -EXTRA_BYTES))
+# define SMALL_OBJ(bytes) ((bytes) < (MAXOBJBYTES - EXTRA_BYTES))
 # define ADD_SLOP(bytes) ((bytes) + EXTRA_BYTES)
 # ifndef MIN_WORDS
     /* MIN_WORDS is the size of the smallest allocated object.	*/
diff --git a/include/private/gcconfig.h b/include/private/gcconfig.h
index 3bc2a48d..a0d12c84 100644
--- a/include/private/gcconfig.h
+++ b/include/private/gcconfig.h
@@ -350,6 +350,14 @@
 #    define S370
 #    define mach_type_known
 # endif
+# if defined(__GNU__)
+#   if defined(__i386__)
+/* The Debian Hurd running on generic PC */  
+#     define  HURD
+#     define  I386
+#     define  mach_type_known
+#    endif 
+# endif
 
 /* Feel free to add more clauses here */
 
@@ -497,6 +505,14 @@
  * word stores of 0 are used instead.
  */
 
+/* If we are using a recent version of gcc, we can use __builtin_unwind_init()
+ * to push the relevant registers onto the stack.  This generally makes
+ * USE_GENERIC_PUSH_REGS the preferred approach for marking from registers.
+ */
+# if defined(__GNUC__) && ((__GNUC__ >= 3) || \
+			   (__GNUC__ == 2 && __GNUC_MINOR__ >= 8))
+#   define HAVE_BUILTIN_UNWIND_INIT
+# endif
 
 # define STACK_GRAN 0x1000000
 # ifdef M68K
@@ -804,6 +820,9 @@
 #     define ALIGN_DOUBLE /* Not strictly necessary, but may give speed   */
 			  /* improvement on Pentiums.			  */
 #   endif
+#   ifdef HAVE_BUILTIN_UNWIND_INIT
+#	define USE_GENERIC_PUSH_REGS
+#   endif
 #   ifdef SEQUENT
 #	define OS_TYPE "SEQUENT"
 	extern int etext;
@@ -1023,6 +1042,17 @@
 #     define DATASTART ((ptr_t) &__nullarea)
 #     define DATAEND ((ptr_t) &_end)
 #   endif
+#   ifdef HURD
+#     define OS_TYPE "HURD"
+#     define STACK_GROWS_DOWN
+#     define HEURISTIC2
+      extern int  __data_start;
+#     define DATASTART ( (ptr_t) (&__data_start))
+      extern int   _end;
+#     define DATAEND ( (ptr_t) (&_end))
+/* #     define MPROTECT_VDB  Not quite working yet? */
+#     define DYNAMIC_LOADING
+#   endif
 # endif
 
 # ifdef NS32K
@@ -1039,7 +1069,6 @@
 
 # ifdef MIPS
 #   define MACH_TYPE "MIPS"
-/* #   define STACKBOTTOM ((ptr_t)0x7fff8000)  sometimes also works.  */
 #   ifdef LINUX
       /* This was developed for a linuxce style platform.  Probably	*/
       /* needs to be tweaked for workstation class machines.		*/
@@ -1047,8 +1076,9 @@
       extern int __data_start;
 #     define DATASTART ((ptr_t)(&__data_start))
 #     define ALIGNMENT 4
-#     define USE_GENERIC_PUSH_REGS 1
-#     define STACKBOTTOM 0x80000000
+#     define USE_GENERIC_PUSH_REGS
+#     define STACKBOTTOM ((ptr_t)0x7fff8000)
+        /* Older toolchains may need 0x80000000.	*/
 	/* In many cases, this should probably use LINUX_STACKBOTTOM 	*/
 	/* instead. But some kernel versions seem to give the wrong	*/
 	/* value from /proc.						*/
@@ -1106,7 +1136,7 @@
 #     define ALIGNMENT 4
 #     define OS_TYPE "NETBSD"
 #     define HEURISTIC2
-#     define USE_GENERIC_PUSH_REGS 1
+#     define USE_GENERIC_PUSH_REGS
 #     ifdef __ELF__
         extern int etext;
 #       define DATASTART GC_data_start
diff --git a/linux_threads.c b/linux_threads.c
index 18891e7f..074be891 100644
--- a/linux_threads.c
+++ b/linux_threads.c
@@ -167,15 +167,16 @@ typedef struct GC_Thread_Rep {
 #   ifdef THREAD_LOCAL_ALLOC
 #	if CPP_WORDSZ == 64 && defined(ALIGN_DOUBLE)
 #	    define GRANULARITY 16
-#	    define NFREELISTS 48
+#	    define NFREELISTS 49
 #	else
 #	    define GRANULARITY 8
-#	    define NFREELISTS 64
+#	    define NFREELISTS 65
 #	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)
+	/* The ith free list corresponds to size i*GRANULARITY */
+#	define INDEX_FROM_BYTES(n) ((ADD_SLOP(n) + GRANULARITY - 1)/GRANULARITY)
+#	define BYTES_FROM_INDEX(i) ((i) * GRANULARITY - EXTRA_BYTES)
+#	define SMALL_ENOUGH(bytes) (ADD_SLOP(bytes) <= \
+				    (NFREELISTS-1)*GRANULARITY)
 	ptr_t ptrfree_freelists[NFREELISTS];
 	ptr_t normal_freelists[NFREELISTS];
 #	ifdef GC_GCJ_SUPPORT
@@ -229,8 +230,8 @@ static void return_freelists(ptr_t *fl, ptr_t *gfl)
     ptr_t q, *qptr;
     size_t nwords;
 
-    for (i = 0; i < NFREELISTS; ++i) {
-	nwords = (i + 1) * (GRANULARITY/sizeof(word));
+    for (i = 1; i < NFREELISTS; ++i) {
+	nwords = i * (GRANULARITY/sizeof(word));
         qptr = fl + i;	
 	q = *qptr;
 	if ((word)q < HBLKSIZE) continue;
@@ -249,6 +250,12 @@ static void return_freelists(ptr_t *fl, ptr_t *gfl)
     }
 }
 
+/* We statically allocate a single "size 0" object. It is linked to	*/
+/* itself, and is thus repeatedly reused for all size 0 allocation	*/
+/* requests.  (Size 0 gcj allocation requests are incorrect, and	*/
+/* we arrange for those to fault asap.)					*/
+static ptr_t size_zero_object = (ptr_t)(&size_zero_object);
+
 /* Each thread structure must be initialized.	*/
 /* This call must be made from the new thread.	*/
 /* Caller holds allocation lock.		*/
@@ -265,13 +272,19 @@ void GC_init_thread_local(GC_thread p)
     if (0 != GC_setspecific(GC_thread_key, p)) {
 	ABORT("Failed to set thread specific allocation pointers");
     }
-    for (i = 0; i < NFREELISTS; ++i) {
+    for (i = 1; 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
     }   
+    /* Set up the size 0 free lists.	*/
+    p -> ptrfree_freelists[0] = (ptr_t)(&size_zero_object);
+    p -> normal_freelists[0] = (ptr_t)(&size_zero_object);
+#   ifdef GC_GCJ_SUPPORT
+        p -> gcj_freelists[0] = (ptr_t)(-1);
+#   endif
 }
 
 #ifdef GC_GCJ_SUPPORT
@@ -664,7 +677,7 @@ void GC_mark_thread_local_free_lists(void)
     
     for (i = 0; i < THREAD_TABLE_SZ; ++i) {
       for (p = GC_threads[i]; 0 != p; p = p -> next) {
-	for (j = 0; j < NFREELISTS; ++j) {
+	for (j = 1; j < NFREELISTS; ++j) {
 	  q = p -> ptrfree_freelists[j];
 	  if ((word)q > HBLKSIZE) GC_set_fl_marks(q);
 	  q = p -> normal_freelists[j];
diff --git a/mach_dep.c b/mach_dep.c
index 8dc7bb9d..776bf690 100644
--- a/mach_dep.c
+++ b/mach_dep.c
@@ -228,7 +228,7 @@ void GC_push_regs()
 	&& !(defined(NETBSD) && defined(__ELF__)) \
 	&& !(defined(OPENBSD) && defined(__ELF__)) \
 	&& !(defined(BEOS) && defined(__ELF__)) \
-	&& !defined(DOS4GW)
+	&& !defined(DOS4GW) && !defined(HURD)
 	/* I386 code, generic code does not appear to work */
 	/* It does appear to work under OS2, and asms dont */
 	/* This is used for some 38g UNIX variants and for CYGWIN32 */
@@ -244,7 +244,8 @@ void GC_push_regs()
 #	if ( defined(I386) && defined(LINUX) && defined(__ELF__) ) \
 	|| ( defined(I386) && defined(FREEBSD) && defined(__ELF__) ) \
 	|| ( defined(I386) && defined(NETBSD) && defined(__ELF__) ) \
-	|| ( defined(I386) && defined(OPENBSD) && defined(__ELF__) )
+	|| ( defined(I386) && defined(OPENBSD) && defined(__ELF__) ) \
+	|| ( defined(I386) && defined(HURD) && defined(__ELF__) )
 
 	/* This is modified for Linux with ELF (Note: _ELF_ only) */
 	/* This section handles FreeBSD with ELF. */
@@ -391,8 +392,8 @@ void GC_push_regs()
 #     endif
 
       /* other machines... */
-#       if !(defined M68K) && !(defined VAX) && !(defined RT) 
-#	if !(defined SPARC) && !(defined I386) && !(defined NS32K)
+#       if !defined(M68K) && !defined(VAX) && !defined(RT) 
+#	if !defined(SPARC) && !defined(I386) && !defined(NS32K)
 #	if !defined(POWERPC) && !defined(UTS4) 
 #       if !defined(PJ) && !(defined(MIPS) && defined(LINUX))
 	    --> bad news <--
@@ -407,27 +408,35 @@ void GC_push_regs()
 void GC_generic_push_regs(cold_gc_frame)
 ptr_t cold_gc_frame;
 {
-	/* Generic code                          */
-	/* The idea is due to Parag Patel at HP. */
-	/* We're not sure whether he would like  */
-	/* to be he acknowledged for it or not.  */
 	{
-	    jmp_buf regs;
-	    register word * i = (word *) regs;
-	    register ptr_t lim = (ptr_t)(regs) + (sizeof regs);
-
-	    /* Setjmp on Sun 3s doesn't clear all of the buffer.  */
-	    /* That tends to preserve garbage.  Clear it.         */
+#	    ifdef HAVE_BUILTIN_UNWIND_INIT
+	      /* This was suggested by Richard Henderson as the way to	*/
+	      /* force callee-save registers and register windows onto	*/
+	      /* the stack.						*/
+	      __builtin_unwind_init();
+#	    else /* !HAVE_BUILTIN_UNWIND_INIT */
+	      /* Generic code                          */
+	      /* The idea is due to Parag Patel at HP. */
+	      /* We're not sure whether he would like  */
+	      /* to be he acknowledged for it or not.  */
+	      jmp_buf regs;
+	      register word * i = (word *) regs;
+	      register ptr_t lim = (ptr_t)(regs) + (sizeof regs);
+
+	      /* Setjmp doesn't always clear all of the buffer.		*/
+	      /* That tends to preserve garbage.  Clear it.   		*/
 		for (; (char *)i < lim; i++) {
 		    *i = 0;
 		}
-#	    if defined(POWERPC) || defined(MSWIN32) || defined(MSWINCE) \
-	       || defined(UTS4) || defined(LINUX)
-		(void) setjmp(regs);
-#	    else
-	        (void) _setjmp(regs);
-#	    endif
-#           if defined(SPARC) || defined(IA64)
+#	      if defined(POWERPC) || defined(MSWIN32) || defined(MSWINCE) \
+	         || defined(UTS4) || defined(LINUX)
+		  (void) setjmp(regs);
+#	      else
+	          (void) _setjmp(regs);
+#	      endif
+#	    endif /* !HAVE_BUILTIN_UNWIND_INIT */
+#           if (defined(SPARC) && !defined(HAVE_BUILTIN_UNWIND_INIT)) \
+		|| defined(IA64)
 	      /* On a register window machine, we need to save register	*/
 	      /* contents on the stack for this to work.  The setjmp	*/
 	      /* is probably not needed on SPARC, since pointers are	*/
@@ -438,6 +447,10 @@ ptr_t cold_gc_frame;
 	        word GC_save_regs_in_stack();
 	      
 	        GC_save_regs_ret_val = GC_save_regs_in_stack();
+		/* On IA64 gcc, could use __builtin_ia64_flushrs() and	*/
+		/* __builtin_ia64_flushrs().  The latter will be done	*/
+		/* implicitly by __builtin_unwind_init() for gcc3.0.1	*/
+		/* and later.						*/
 	      }
 #           endif
 	    GC_push_current_stack(cold_gc_frame);
@@ -511,7 +524,7 @@ ptr_t cold_gc_frame;
 /* returns arg.  Stack clearing is crucial on SPARC, so we supply	*/
 /* an assembly version that's more careful.  Assumes limit is hotter	*/
 /* than sp, and limit is 8 byte aligned.				*/
-#if defined(ASM_CLEAR_CODE) && !defined(THREADS)
+#if defined(ASM_CLEAR_CODE)
 #ifndef SPARC
 	--> fix it
 #endif
diff --git a/misc.c b/misc.c
index 40d45266..94ef15d3 100644
--- a/misc.c
+++ b/misc.c
@@ -45,7 +45,7 @@
 	  mutex_t GC_allocate_ml;	/* Implicitly initialized.	*/
 #	else
 #          ifdef WIN32_THREADS
-#	      if defined(_DLL) || defined(GC_DLL)
+#	      if !defined(GC_NOT_DLL) && (defined(_DLL) || defined(GC_DLL))
 		 __declspec(dllexport) CRITICAL_SECTION GC_allocate_ml;
 #	      else
 		 CRITICAL_SECTION GC_allocate_ml;
@@ -301,6 +301,8 @@ ptr_t arg;
     if (++random_no % 13 == 0) {
 	limit = sp;
 	MAKE_HOTTER(limit, BIG_CLEAR_SIZE*sizeof(word));
+        limit &= ~0xf;	/* Make it sufficiently aligned for assembly	*/
+        		/* implementations of GC_clear_stack_inner.	*/
 	return GC_clear_stack_inner(arg, limit);
     } else {
 	BZERO(dummy, SMALL_CLEAR_SIZE*sizeof(word));
@@ -691,7 +693,7 @@ out:
   }
 
   int GC_write(buf, len)
-  char * buf;
+  GC_CONST char * buf;
   size_t len;
   {
       BOOL tmp;
diff --git a/os_dep.c b/os_dep.c
index 9da17928..79bed4c7 100644
--- a/os_dep.c
+++ b/os_dep.c
@@ -63,25 +63,24 @@
 /* Blatantly OS dependent routines, except for those that are related 	*/
 /* to dynamic loading.							*/
 
-# if !defined(THREADS) && !defined(STACKBOTTOM) && defined(HEURISTIC2)
+# if defined(HEURISTIC2) || defined(SEARCH_FOR_DATA_START)
 #   define NEED_FIND_LIMIT
 # endif
 
-# if defined(IRIX_THREADS) || defined(HPUX_THREADS)
+# if !defined(STACKBOTTOM) && defined(HEURISTIC2)
 #   define NEED_FIND_LIMIT
 # endif
 
-# if (defined(SUNOS4) && defined(DYNAMIC_LOADING)) && !defined(PCR)
+# if defined(IRIX_THREADS) || defined(HPUX_THREADS)
 #   define NEED_FIND_LIMIT
 # endif
 
-# if (defined(SVR4) || defined(AUX) || defined(DGUX)) && !defined(PCR)
+# if (defined(SUNOS4) && defined(DYNAMIC_LOADING)) && !defined(PCR)
 #   define NEED_FIND_LIMIT
 # endif
 
-# if defined(LINUX) && \
-     (defined(POWERPC) || defined(SPARC) || defined(ALPHA) || defined(IA64) \
-      || defined(MIPS))
+# if (defined(SVR4) || defined(AUX) || defined(DGUX) \
+      || (defined(LINUX) && defined(SPARC))) && !defined(PCR)
 #   define NEED_FIND_LIMIT
 # endif
 
@@ -123,8 +122,10 @@
 # include <fcntl.h>
 #endif
 
-#ifdef SUNOS5SIGS
-# include <sys/siginfo.h>
+#if defined(SUNOS5SIGS) || defined (HURD) || defined(LINUX)
+# ifdef SUNOS5SIGS
+#  include <sys/siginfo.h>
+# endif
 # undef setjmp
 # undef longjmp
 # define setjmp(env) sigsetjmp(env, 1)
@@ -338,7 +339,7 @@ void GC_enable_signals(void)
       && !defined(MSWINCE) \
       && !defined(MACOS) && !defined(DJGPP) && !defined(DOS4GW)
 
-#   if defined(sigmask) && !defined(UTS4)
+#   if defined(sigmask) && !defined(UTS4) && !defined(HURD)
 	/* Use the traditional BSD interface */
 #	define SIGSET_T int
 #	define SIG_DEL(set, signal) (set) &= ~(sigmask(signal))
@@ -519,7 +520,7 @@ ptr_t GC_get_stack_base()
 #   undef GC_AMIGA_SB
 # endif /* AMIGA */
 
-# if defined(NEED_FIND_LIMIT) || defined(UNIX_LIKE)
+# if defined(NEED_FIND_LIMIT) || (defined(UNIX_LIKE) && !defined(ECOS))
 
 #   ifdef __STDC__
 	typedef void (*handler)(int);
@@ -527,9 +528,9 @@ ptr_t GC_get_stack_base()
 	typedef void (*handler)();
 #   endif
 
-#   if defined(SUNOS5SIGS) || defined(IRIX5) || defined(OSF1)
+#   if defined(SUNOS5SIGS) || defined(IRIX5) || defined(OSF1) || defined(HURD)
 	static struct sigaction old_segv_act;
-#	if defined(_sigargs) || defined(HPUX) /* !Irix6.x */
+#	if defined(_sigargs) /* !Irix6.x */ || defined(HPUX) || defined(HURD)
 	    static struct sigaction old_bus_act;
 #	endif
 #   else
@@ -543,12 +544,16 @@ ptr_t GC_get_stack_base()
       handler h;
 #   endif
     {
-# ifndef ECOS
-#	if defined(SUNOS5SIGS) || defined(IRIX5) || defined(OSF1)
+#	if defined(SUNOS5SIGS) || defined(IRIX5)  \
+        || defined(OSF1) || defined(HURD)
 	  struct sigaction	act;
 
 	  act.sa_handler	= h;
-          act.sa_flags          = SA_RESTART | SA_NODEFER;
+#	  ifdef SUNOS5SIGS
+            act.sa_flags          = SA_RESTART | SA_NODEFER;
+#         else
+            act.sa_flags          = SA_RESTART;
+#	  endif
           /* The presence of SA_NODEFER represents yet another gross    */
           /* hack.  Under Solaris 2.3, siglongjmp doesn't appear to     */
           /* interact correctly with -lthread.  We hide the confusion   */
@@ -564,7 +569,7 @@ ptr_t GC_get_stack_base()
 #	  else
 	        (void) sigaction(SIGSEGV, &act, &old_segv_act);
 #		if defined(IRIX5) && defined(_sigargs) /* Irix 5.x, not 6.x */ \
-		   || defined(HPUX)
+		   || defined(HPUX) || defined(HURD)
 		    /* Under Irix 5.x or HP/UX, we may get SIGBUS.	*/
 		    /* Pthreads doesn't exist under Irix 5.x, so we	*/
 		    /* don't have to worry in the threads case.		*/
@@ -577,7 +582,6 @@ ptr_t GC_get_stack_base()
 	    old_bus_handler = signal(SIGBUS, h);
 #	  endif
 #	endif
-# endif /* ECOS */
     }
 # endif /* NEED_FIND_LIMIT || UNIX_LIKE */
 
@@ -600,11 +604,11 @@ ptr_t GC_get_stack_base()
     
     void GC_reset_fault_handler()
     {
-# ifndef ECOS
-#       if defined(SUNOS5SIGS) || defined(IRIX5) || defined(OSF1)
+#       if defined(SUNOS5SIGS) || defined(IRIX5) \
+	   || defined(OSF1) || defined(HURD)
 	  (void) sigaction(SIGSEGV, &old_segv_act, 0);
 #	  if defined(IRIX5) && defined(_sigargs) /* Irix 5.x, not 6.x */ \
-	     || defined(HPUX)
+	     || defined(HPUX) || defined(HURD)
 	      (void) sigaction(SIGBUS, &old_bus_act, 0);
 #	  endif
 #       else
@@ -613,7 +617,6 @@ ptr_t GC_get_stack_base()
 	    (void) signal(SIGBUS, old_bus_handler);
 #	  endif
 #       endif
-# endif /* ECOS */
     }
 
     /* Return the first nonaddressible location > p (up) or 	*/
@@ -622,7 +625,6 @@ ptr_t GC_get_stack_base()
     ptr_t p;
     GC_bool up;
     {
-# ifndef ECOS
         static VOLATILE ptr_t result;
     		/* Needs to be static, since otherwise it may not be	*/
     		/* preserved across the longjmp.  Can safely be 	*/
@@ -648,14 +650,9 @@ ptr_t GC_get_stack_base()
 	    result += MIN_PAGE_SIZE;
  	}
 	return(result);
-# else /* ECOS */
-	abort();
-# endif /* ECOS */
     }
 # endif
 
-# ifndef ECOS
-
 #ifdef LINUX_STACKBOTTOM
 
 #include <sys/types.h>
@@ -753,7 +750,7 @@ ptr_t GC_get_stack_base()
 #endif /* FREEBSD_STACKBOTTOM */
 
 #if !defined(BEOS) && !defined(AMIGA) && !defined(MSWIN32) \
-    && !defined(MSWINCE) && !defined(OS2)
+    && !defined(MSWINCE) && !defined(OS2) && !defined(ECOS)
 
 ptr_t GC_get_stack_base()
 {
@@ -807,7 +804,6 @@ ptr_t GC_get_stack_base()
     	return(result);
 #   endif /* STACKBOTTOM */
 }
-# endif /* ECOS */
 
 # endif /* ! AMIGA, !OS 2, ! MS Windows, !BEOS */
 
@@ -1808,7 +1804,8 @@ struct hblk *h;
 #if defined(SUNOS4) || defined(FREEBSD)
     typedef void (* SIG_PF)();
 #endif
-#if defined(SUNOS5SIGS) || defined(OSF1) || defined(LINUX) || defined(MACOSX)
+#if defined(SUNOS5SIGS) || defined(OSF1) || defined(LINUX) \
+    || defined(MACOSX) || defined(HURD)
 # ifdef __STDC__
     typedef void (* SIG_PF)(int);
 # else
@@ -1826,7 +1823,7 @@ struct hblk *h;
 #   define SIG_DFL (SIG_PF) (-1)
 #endif
 
-#if defined(IRIX5) || defined(OSF1)
+#if defined(IRIX5) || defined(OSF1) || defined(HURD)
     typedef void (* REAL_SIG_PF)(int, int, struct sigcontext *);
 #endif
 #if defined(SUNOS5SIGS)
@@ -2013,7 +2010,7 @@ SIG_PF GC_old_segv_handler;	/* Also old MSWIN32 ACCESS_VIOLATION filter */
 #ifdef GC_TEST_AND_SET_DEFINED
   static VOLATILE unsigned int fault_handler_lock = 0;
   void async_set_pht_entry_from_index(VOLATILE page_hash_table db, int index) {
-    while (GC_test_and_set(&fault_handler_lock));
+    while (GC_test_and_set(&fault_handler_lock)) {}
     /* Could also revert to set_pht_entry_from_index_safe if initial	*/
     /* GC_test_and_set fails.						*/
     set_pht_entry_from_index(db, index);
@@ -2067,16 +2064,21 @@ SIG_PF GC_old_segv_handler;	/* Also old MSWIN32 ACCESS_VIOLATION filter */
 #     define CODE_OK (code == BUS_PAGE_FAULT)
 #   endif
 # endif
-# if defined(IRIX5) || defined(OSF1)
+# if defined(IRIX5) || defined(OSF1) || defined(HURD)
 #   include <errno.h>
     void GC_write_fault_handler(int sig, int code, struct sigcontext *scp)
-#   define SIG_OK (sig == SIGSEGV)
 #   ifdef OSF1
+#     define SIG_OK (sig == SIGSEGV)
 #     define CODE_OK (code == 2 /* experimentally determined */)
 #   endif
 #   ifdef IRIX5
+#     define SIG_OK (sig == SIGSEGV)
 #     define CODE_OK (code == EACCES)
 #   endif
+#   ifdef HURD
+#     define SIG_OK (sig == SIGBUS || sig == SIGSEGV) 	
+#     define CODE_OK  TRUE
+#   endif
 # endif
 # if defined(LINUX)
 #   if defined(ALPHA) || defined(M68K)
@@ -2131,6 +2133,9 @@ SIG_PF GC_old_segv_handler;	/* Also old MSWIN32 ACCESS_VIOLATION filter */
 # endif
 {
     register unsigned i;
+#   if defined(HURD) 
+	char *addr = (char *) code;
+#   endif
 #   ifdef IRIX5
 	char * addr = (char *) (size_t) (scp -> sc_badvaddr);
 #   endif
@@ -2254,7 +2259,7 @@ SIG_PF GC_old_segv_handler;	/* Also old MSWIN32 ACCESS_VIOLATION filter */
 #		    endif
 		    return;
 #		endif
-#		if defined (IRIX5) || defined(OSF1)
+#		if defined (IRIX5) || defined(OSF1) || defined(HURD)
 		    (*(REAL_SIG_PF)old_handler) (sig, code, scp);
 		    return;
 #		endif
@@ -2332,13 +2337,14 @@ struct hblk *h;
 
 void GC_dirty_init()
 {
-#   if defined(SUNOS5SIGS) || defined(IRIX5) || defined(LINUX) || defined(OSF1)
+#   if defined(SUNOS5SIGS) || defined(IRIX5) || defined(LINUX) || \
+       defined(OSF1) || defined(HURD)
       struct sigaction	act, oldact;
       /* We should probably specify SA_SIGINFO for Linux, and handle 	*/
       /* the different architectures more uniformly.			*/
-#     if defined(IRIX5) || defined(LINUX) || defined(OSF1)
+#     if defined(IRIX5) || defined(LINUX) || defined(OSF1) || defined(HURD)
     	act.sa_flags	= SA_RESTART;
-        act.sa_handler  = GC_write_fault_handler;
+        act.sa_handler  = (SIG_PF)GC_write_fault_handler;
 #     else
     	act.sa_flags	= SA_RESTART | SA_SIGINFO;
         act.sa_sigaction = GC_write_fault_handler;
@@ -2390,7 +2396,8 @@ void GC_dirty_init()
 #	endif
       }
 #   endif
-#   if defined(SUNOS5SIGS) || defined(IRIX5) || defined(LINUX) || defined(OSF1)
+#   if defined(SUNOS5SIGS) || defined(IRIX5) || defined(LINUX) \
+       || defined(OSF1) || defined(HURD)
       /* SUNOS5SIGS includes HPUX */
 #     if defined(IRIX_THREADS)
       	sigaction(SIGSEGV, 0, &oldact);
@@ -2398,7 +2405,7 @@ void GC_dirty_init()
 #     else
       	sigaction(SIGSEGV, &act, &oldact);
 #     endif
-#     if defined(_sigargs)
+#     if defined(_sigargs) || defined(HURD)
 	/* This is Irix 5.x, not 6.x.  Irix 5.x does not have	*/
 	/* sa_sigaction.					*/
 	GC_old_segv_handler = oldact.sa_handler;
@@ -2419,7 +2426,7 @@ void GC_dirty_init()
 #       endif
       }
 #   endif
-#   if defined(MACOSX) || defined(HPUX) || defined(LINUX)
+#   if defined(MACOSX) || defined(HPUX) || defined(LINUX) || defined(HURD)
       sigaction(SIGBUS, &act, &oldact);
       GC_old_bus_handler = oldact.sa_handler;
       if (GC_old_bus_handler == SIG_IGN) {
@@ -2568,10 +2575,14 @@ word len;
 	    result = readv(fd, &iov, 1);
 	}
 #   else
+#     if defined(HURD)	
+	result = __read(fd, buf, nbyte);
+#     else
  	/* The two zero args at the end of this list are because one
  	   IA-64 syscall() implementation actually requires six args
  	   to be passed, even though they aren't always used. */
      	result = syscall(SYS_read, fd, buf, nbyte, 0, 0);
+#     endif /* !HURD */
 #   endif
     GC_end_syscall();
     return(result);
diff --git a/powerpc_macosx_mach_dep.s b/powerpc_macosx_mach_dep.s
index 72cdfdc8..92f06286 100755
--- a/powerpc_macosx_mach_dep.s
+++ b/powerpc_macosx_mach_dep.s
@@ -16,10 +16,10 @@ _GC_push_regs:
     stw     r0,8(r1)    ; save return address
     stwu    r1,-spaceToSave(r1)   ; skip over caller save area
     ;
-    mr      r3,r2         ; mark from r2. Well I'm not really sure
+    mr      r3,r2         ; mark from r2. Well Im not really sure
                           ; that this is necessary or even the right
-                          ; thing to do - at least it doesn't harm...
-                          ; According to Apple's docs it points to
+                          ; thing to do - at least it doesnt harm...
+                          ; According to Apples docs it points to
                           ; the direct data area, whatever that is...
     bl 	    L_GC_push_one$stub
     mr      r3,r13        ; mark from r13-r31
diff --git a/version.h b/version.h
index 141f4a5e..7efee18f 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define GC_VERSION_MAJOR 6
 #define GC_VERSION_MINOR 0
-#define GC_ALPHA_VERSION 8
+#define GC_ALPHA_VERSION GC_NOT_ALPHA
 
 #   define GC_NOT_ALPHA 0xff