Initial revision

1 files changed, 2461 insertions, 0 deletions

diff --git a/gc/os_dep.c b/gc/os_dep.c
new file mode 100644
index 0000000..0236248
--- /dev/null
+++ b/gc/os_dep.c
@@ -0,0 +1,2461 @@
+/*
+ * Copyright (c) 1991-1995 by Xerox Corporation.  All rights reserved.
+ * Copyright (c) 1996-1997 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.
+ */
+
+# include "gc_priv.h"
+
+# if defined(LINUX) && !defined(POWERPC)
+#   include <linux/version.h>
+#   if (LINUX_VERSION_CODE <= 0x10400)
+      /* Ugly hack to get struct sigcontext_struct definition.  Required      */
+      /* for some early 1.3.X releases.  Will hopefully go away soon. */
+      /* in some later Linux releases, asm/sigcontext.h may have to   */
+      /* be included instead.                                         */
+#     define __KERNEL__
+#     include <asm/signal.h>
+#     undef __KERNEL__
+#   else
+      /* Kernels prior to 2.1.1 defined struct sigcontext_struct instead of */
+      /* struct sigcontext.  libc6 (glibc2) uses "struct sigcontext" in     */
+      /* prototypes, so we have to include the top-level sigcontext.h to    */
+      /* make sure the former gets defined to be the latter if appropriate. */
+#     include <features.h>
+#     if 2 <= __GLIBC__
+#       if 0 == __GLIBC_MINOR__
+	  /* glibc 2.1 no longer has sigcontext.h.  But signal.h	*/
+	  /* has the right declaration for glibc 2.1.			*/
+#         include <sigcontext.h>
+#       endif /* 0 == __GLIBC_MINOR__ */
+#     else /* not 2 <= __GLIBC__ */
+        /* libc5 doesn't have <sigcontext.h>: go directly with the kernel   */
+        /* one.  Check LINUX_VERSION_CODE to see which we should reference. */
+#       include <asm/sigcontext.h>
+#     endif /* 2 <= __GLIBC__ */
+#   endif
+# endif
+# if !defined(OS2) && !defined(PCR) && !defined(AMIGA) && !defined(MACOS)
+#   include <sys/types.h>
+#   if !defined(MSWIN32) && !defined(SUNOS4)
+#   	include <unistd.h>
+#   endif
+# endif
+
+# include <stdio.h>
+# include <signal.h>
+
+/* Blatantly OS dependent routines, except for those that are related 	*/
+/* dynamic loading.							*/
+
+# if !defined(THREADS) && !defined(STACKBOTTOM) && defined(HEURISTIC2)
+#   define NEED_FIND_LIMIT
+# endif
+
+# if defined(IRIX_THREADS)
+#   define NEED_FIND_LIMIT
+# endif
+
+# if (defined(SUNOS4) & defined(DYNAMIC_LOADING)) && !defined(PCR)
+#   define NEED_FIND_LIMIT
+# endif
+
+# if (defined(SVR4) || defined(AUX) || defined(DGUX)) && !defined(PCR)
+#   define NEED_FIND_LIMIT
+# endif
+
+# if defined(LINUX) && (defined(POWERPC) || defined(SPARC) || \
+      defined(ALPHA) || defined(MIPS))
+#   define NEED_FIND_LIMIT
+# endif
+
+#ifdef NEED_FIND_LIMIT
+#   include <setjmp.h>
+#endif
+
+#ifdef FREEBSD
+#  include <machine/trap.h>
+#endif
+
+#ifdef AMIGA
+# include <proto/exec.h>
+# include <proto/dos.h>
+# include <dos/dosextens.h>
+# include <workbench/startup.h>
+#endif
+
+#ifdef MSWIN32
+# define WIN32_LEAN_AND_MEAN
+# define NOSERVICE
+# include <windows.h>
+#endif
+
+#ifdef MACOS
+# include <Processes.h>
+#endif
+
+#ifdef IRIX5
+# include <sys/uio.h>
+# include <malloc.h>   /* for locking */
+#endif
+#ifdef USE_MMAP
+# include <sys/types.h>
+# include <sys/mman.h>
+# include <sys/stat.h>
+# include <fcntl.h>
+#endif
+
+#ifdef SUNOS5SIGS
+# include <sys/siginfo.h>
+# undef setjmp
+# undef longjmp
+# define setjmp(env) sigsetjmp(env, 1)
+# define longjmp(env, val) siglongjmp(env, val)
+# define jmp_buf sigjmp_buf
+#endif
+
+#ifdef DJGPP
+  /* Apparently necessary for djgpp 2.01.  May casuse problems with	*/
+  /* other versions.							*/
+  typedef long unsigned int caddr_t;
+#endif
+
+#ifdef PCR
+# include "il/PCR_IL.h"
+# include "th/PCR_ThCtl.h"
+# include "mm/PCR_MM.h"
+#endif
+
+#if !defined(NO_EXECUTE_PERMISSION)
+# define OPT_PROT_EXEC PROT_EXEC
+#else
+# define OPT_PROT_EXEC 0
+#endif
+
+#if defined(LINUX) && (defined(POWERPC) || defined(SPARC) || \
+      defined(ALPHA) || defined(MIPS))
+  /* The I386 case can be handled without a search.  The Alpha case	*/
+  /* used to be handled differently as well, but the rules changed	*/
+  /* for recent Linux versions.  This seems to be the easiest way to	*/
+  /* cover all versions.						*/
+  ptr_t GC_data_start;
+
+  extern char * GC_copyright[];  /* Any data symbol would do. */
+
+  void GC_init_linux_data_start()
+  {
+    extern ptr_t GC_find_limit();
+
+    GC_data_start = GC_find_limit((ptr_t)GC_copyright, FALSE);
+  }
+#endif
+
+# ifdef OS2
+
+# include <stddef.h>
+
+# if !defined(__IBMC__) && !defined(__WATCOMC__) /* e.g. EMX */
+
+struct exe_hdr {
+    unsigned short      magic_number;
+    unsigned short      padding[29];
+    long                new_exe_offset;
+};
+
+#define E_MAGIC(x)      (x).magic_number
+#define EMAGIC          0x5A4D  
+#define E_LFANEW(x)     (x).new_exe_offset
+
+struct e32_exe {
+    unsigned char       magic_number[2]; 
+    unsigned char       byte_order; 
+    unsigned char       word_order; 
+    unsigned long       exe_format_level;
+    unsigned short      cpu;       
+    unsigned short      os;
+    unsigned long       padding1[13];
+    unsigned long       object_table_offset;
+    unsigned long       object_count;    
+    unsigned long       padding2[31];
+};
+
+#define E32_MAGIC1(x)   (x).magic_number[0]
+#define E32MAGIC1       'L'
+#define E32_MAGIC2(x)   (x).magic_number[1]
+#define E32MAGIC2       'X'
+#define E32_BORDER(x)   (x).byte_order
+#define E32LEBO         0
+#define E32_WORDER(x)   (x).word_order
+#define E32LEWO         0
+#define E32_CPU(x)      (x).cpu
+#define E32CPU286       1
+#define E32_OBJTAB(x)   (x).object_table_offset
+#define E32_OBJCNT(x)   (x).object_count
+
+struct o32_obj {
+    unsigned long       size;  
+    unsigned long       base;
+    unsigned long       flags;  
+    unsigned long       pagemap;
+    unsigned long       mapsize; 
+    unsigned long       reserved;
+};
+
+#define O32_FLAGS(x)    (x).flags
+#define OBJREAD         0x0001L
+#define OBJWRITE        0x0002L
+#define OBJINVALID      0x0080L
+#define O32_SIZE(x)     (x).size
+#define O32_BASE(x)     (x).base
+
+# else  /* IBM's compiler */
+
+/* A kludge to get around what appears to be a header file bug */
+# ifndef WORD
+#   define WORD unsigned short
+# endif
+# ifndef DWORD
+#   define DWORD unsigned long
+# endif
+
+# define EXE386 1
+# include <newexe.h>
+# include <exe386.h>
+
+# endif  /* __IBMC__ */
+
+# define INCL_DOSEXCEPTIONS
+# define INCL_DOSPROCESS
+# define INCL_DOSERRORS
+# define INCL_DOSMODULEMGR
+# define INCL_DOSMEMMGR
+# include <os2.h>
+
+
+/* Disable and enable signals during nontrivial allocations	*/
+
+void GC_disable_signals(void)
+{
+    ULONG nest;
+    
+    DosEnterMustComplete(&nest);
+    if (nest != 1) ABORT("nested GC_disable_signals");
+}
+
+void GC_enable_signals(void)
+{
+    ULONG nest;
+    
+    DosExitMustComplete(&nest);
+    if (nest != 0) ABORT("GC_enable_signals");
+}
+
+
+# else
+
+#  if !defined(PCR) && !defined(AMIGA) && !defined(MSWIN32) \
+      && !defined(MACOS) && !defined(DJGPP) && !defined(DOS4GW)
+
+#   if defined(sigmask) && !defined(UTS4)
+	/* Use the traditional BSD interface */
+#	define SIGSET_T int
+#	define SIG_DEL(set, signal) (set) &= ~(sigmask(signal))
+#	define SIG_FILL(set)  (set) = 0x7fffffff
+    	  /* Setting the leading bit appears to provoke a bug in some	*/
+    	  /* longjmp implementations.  Most systems appear not to have	*/
+    	  /* a signal 32.						*/
+#	define SIGSETMASK(old, new) (old) = sigsetmask(new)
+#   else
+	/* Use POSIX/SYSV interface	*/
+#	define SIGSET_T sigset_t
+#	define SIG_DEL(set, signal) sigdelset(&(set), (signal))
+#	define SIG_FILL(set) sigfillset(&set)
+#	define SIGSETMASK(old, new) sigprocmask(SIG_SETMASK, &(new), &(old))
+#   endif
+
+static GC_bool mask_initialized = FALSE;
+
+static SIGSET_T new_mask;
+
+static SIGSET_T old_mask;
+
+static SIGSET_T dummy;
+
+#if defined(PRINTSTATS) && !defined(THREADS)
+# define CHECK_SIGNALS
+  int GC_sig_disabled = 0;
+#endif
+
+void GC_disable_signals()
+{
+    if (!mask_initialized) {
+    	SIG_FILL(new_mask);
+
+	SIG_DEL(new_mask, SIGSEGV);
+	SIG_DEL(new_mask, SIGILL);
+	SIG_DEL(new_mask, SIGQUIT);
+#	ifdef SIGBUS
+	    SIG_DEL(new_mask, SIGBUS);
+#	endif
+#	ifdef SIGIOT
+	    SIG_DEL(new_mask, SIGIOT);
+#	endif
+#	ifdef SIGEMT
+	    SIG_DEL(new_mask, SIGEMT);
+#	endif
+#	ifdef SIGTRAP
+	    SIG_DEL(new_mask, SIGTRAP);
+#	endif 
+	mask_initialized = TRUE;
+    }
+#   ifdef CHECK_SIGNALS
+	if (GC_sig_disabled != 0) ABORT("Nested disables");
+	GC_sig_disabled++;
+#   endif
+    SIGSETMASK(old_mask,new_mask);
+}
+
+void GC_enable_signals()
+{
+#   ifdef CHECK_SIGNALS
+	if (GC_sig_disabled != 1) ABORT("Unmatched enable");
+	GC_sig_disabled--;
+#   endif
+    SIGSETMASK(dummy,old_mask);
+}
+
+#  endif  /* !PCR */
+
+# endif /*!OS/2 */
+
+/* Ivan Demakov: simplest way (to me) */
+#ifdef DOS4GW
+  void GC_disable_signals() { }
+  void GC_enable_signals() { }
+#endif
+
+/* Find the page size */
+word GC_page_size;
+
+# ifdef MSWIN32
+  void GC_setpagesize()
+  {
+    SYSTEM_INFO sysinfo;
+    
+    GetSystemInfo(&sysinfo);
+    GC_page_size = sysinfo.dwPageSize;
+  }
+
+# else
+#   if defined(MPROTECT_VDB) || defined(PROC_VDB) || defined(USE_MMAP) \
+       || defined(USE_MUNMAP)
+	void GC_setpagesize()
+	{
+	    GC_page_size = GETPAGESIZE();
+	}
+#   else
+	/* It's acceptable to fake it. */
+	void GC_setpagesize()
+	{
+	    GC_page_size = HBLKSIZE;
+	}
+#   endif
+# endif
+
+/* 
+ * Find the base of the stack. 
+ * Used only in single-threaded environment.
+ * With threads, GC_mark_roots needs to know how to do this.
+ * Called with allocator lock held.
+ */
+# ifdef MSWIN32 
+# define is_writable(prot) ((prot) == PAGE_READWRITE \
+			    || (prot) == PAGE_WRITECOPY \
+			    || (prot) == PAGE_EXECUTE_READWRITE \
+			    || (prot) == PAGE_EXECUTE_WRITECOPY)
+/* Return the number of bytes that are writable starting at p.	*/
+/* The pointer p is assumed to be page aligned.			*/
+/* If base is not 0, *base becomes the beginning of the 	*/
+/* allocation region containing p.				*/
+word GC_get_writable_length(ptr_t p, ptr_t *base)
+{
+    MEMORY_BASIC_INFORMATION buf;
+    word result;
+    word protect;
+    
+    result = VirtualQuery(p, &buf, sizeof(buf));
+    if (result != sizeof(buf)) ABORT("Weird VirtualQuery result");
+    if (base != 0) *base = (ptr_t)(buf.AllocationBase);
+    protect = (buf.Protect & ~(PAGE_GUARD | PAGE_NOCACHE));
+    if (!is_writable(protect)) {
+        return(0);
+    }
+    if (buf.State != MEM_COMMIT) return(0);
+    return(buf.RegionSize);
+}
+
+ptr_t GC_get_stack_base()
+{
+    int dummy;
+    ptr_t sp = (ptr_t)(&dummy);
+    ptr_t trunc_sp = (ptr_t)((word)sp & ~(GC_page_size - 1));
+    word size = GC_get_writable_length(trunc_sp, 0);
+   
+    return(trunc_sp + size);
+}
+
+
+# else
+
+# ifdef OS2
+
+ptr_t GC_get_stack_base()
+{
+    PTIB ptib;
+    PPIB ppib;
+    
+    if (DosGetInfoBlocks(&ptib, &ppib) != NO_ERROR) {
+    	GC_err_printf0("DosGetInfoBlocks failed\n");
+    	ABORT("DosGetInfoBlocks failed\n");
+    }
+    return((ptr_t)(ptib -> tib_pstacklimit));
+}
+
+# else
+
+# ifdef AMIGA
+
+ptr_t GC_get_stack_base()
+{
+    struct Process *proc = (struct Process*)SysBase->ThisTask;
+ 
+    /* Reference: Amiga Guru Book Pages: 42,567,574 */
+    if (proc->pr_Task.tc_Node.ln_Type==NT_PROCESS
+        && proc->pr_CLI != NULL) {
+	/* first ULONG is StackSize */
+	/*longPtr = proc->pr_ReturnAddr;
+	size = longPtr[0];*/
+
+	return (char *)proc->pr_ReturnAddr + sizeof(ULONG);
+    } else {
+	return (char *)proc->pr_Task.tc_SPUpper;
+    }
+}
+
+#if 0 /* old version */
+ptr_t GC_get_stack_base()
+{
+    extern struct WBStartup *_WBenchMsg;
+    extern long __base;
+    extern long __stack;
+    struct Task *task;
+    struct Process *proc;
+    struct CommandLineInterface *cli;
+    long size;
+
+    if ((task = FindTask(0)) == 0) {
+	GC_err_puts("Cannot find own task structure\n");
+	ABORT("task missing");
+    }
+    proc = (struct Process *)task;
+    cli = BADDR(proc->pr_CLI);
+
+    if (_WBenchMsg != 0 || cli == 0) {
+	size = (char *)task->tc_SPUpper - (char *)task->tc_SPLower;
+    } else {
+	size = cli->cli_DefaultStack * 4;
+    }
+    return (ptr_t)(__base + GC_max(size, __stack));
+}
+#endif /* 0 */
+
+# else /* !AMIGA, !OS2, ... */
+
+# ifdef NEED_FIND_LIMIT
+  /* Some tools to implement HEURISTIC2	*/
+#   define MIN_PAGE_SIZE 256	/* Smallest conceivable page size, bytes */
+    /* static */ jmp_buf GC_jmp_buf;
+    
+    /*ARGSUSED*/
+    void GC_fault_handler(sig)
+    int sig;
+    {
+        longjmp(GC_jmp_buf, 1);
+    }
+
+#   ifdef __STDC__
+	typedef void (*handler)(int);
+#   else
+	typedef void (*handler)();
+#   endif
+
+#   if defined(SUNOS5SIGS) || defined(IRIX5) || defined(OSF1)
+	static struct sigaction old_segv_act;
+#	if defined(_sigargs) /* !Irix6.x */
+	    static struct sigaction old_bus_act;
+#	endif
+#   else
+        static handler old_segv_handler, old_bus_handler;
+#   endif
+    
+    void GC_setup_temporary_fault_handler()
+    {
+#	if defined(SUNOS5SIGS) || defined(IRIX5) || defined(OSF1)
+	  struct sigaction	act;
+
+	  act.sa_handler	= GC_fault_handler;
+          act.sa_flags          = SA_RESTART | SA_NODEFER;
+          /* 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   */
+          /* by making sure that signal handling doesn't affect the     */
+          /* signal mask.                                               */
+
+	  (void) sigemptyset(&act.sa_mask);
+#	  ifdef IRIX_THREADS
+		/* Older versions have a bug related to retrieving and	*/
+		/* and setting a handler at the same time.		*/
+	        (void) sigaction(SIGSEGV, 0, &old_segv_act);
+	        (void) sigaction(SIGSEGV, &act, 0);
+#	  else
+	        (void) sigaction(SIGSEGV, &act, &old_segv_act);
+#		ifdef _sigargs	/* Irix 5.x, not 6.x */
+		    /* Under 5.x, we may get SIGBUS.			*/
+		    /* Pthreads doesn't exist under 5.x, so we don't	*/
+		    /* have to worry in the threads case.		*/
+		    (void) sigaction(SIGBUS, &act, &old_bus_act);
+#		endif
+#	  endif	/* IRIX_THREADS */
+#	else
+    	  old_segv_handler = signal(SIGSEGV, GC_fault_handler);
+#	  ifdef SIGBUS
+	    old_bus_handler = signal(SIGBUS, GC_fault_handler);
+#	  endif
+#	endif
+    }
+    
+    void GC_reset_fault_handler()
+    {
+#       if defined(SUNOS5SIGS) || defined(IRIX5) || defined(OSF1)
+	  (void) sigaction(SIGSEGV, &old_segv_act, 0);
+#	  ifdef _sigargs	/* Irix 5.x, not 6.x */
+	      (void) sigaction(SIGBUS, &old_bus_act, 0);
+#	  endif
+#       else
+  	  (void) signal(SIGSEGV, old_segv_handler);
+#	  ifdef SIGBUS
+	    (void) signal(SIGBUS, old_bus_handler);
+#	  endif
+#       endif
+    }
+
+    /* Return the first nonaddressible location > p (up) or 	*/
+    /* the smallest location q s.t. [q,p] is addressible (!up).	*/
+    ptr_t GC_find_limit(p, up)
+    ptr_t p;
+    GC_bool up;
+    {
+        static VOLATILE ptr_t result;
+    		/* Needs to be static, since otherwise it may not be	*/
+    		/* preserved across the longjmp.  Can safely be 	*/
+    		/* static since it's only called once, with the		*/
+    		/* allocation lock held.				*/
+
+
+	GC_setup_temporary_fault_handler();
+	if (setjmp(GC_jmp_buf) == 0) {
+	    result = (ptr_t)(((word)(p))
+			      & ~(MIN_PAGE_SIZE-1));
+	    for (;;) {
+ 	        if (up) {
+		    result += MIN_PAGE_SIZE;
+ 	        } else {
+		    result -= MIN_PAGE_SIZE;
+ 	        }
+		GC_noop1((word)(*result));
+	    }
+	}
+	GC_reset_fault_handler();
+ 	if (!up) {
+	    result += MIN_PAGE_SIZE;
+ 	}
+	return(result);
+    }
+# endif
+
+
+ptr_t GC_get_stack_base()
+{
+    word dummy;
+    ptr_t result;
+
+#   define STACKBOTTOM_ALIGNMENT_M1 ((word)STACK_GRAN - 1)
+
+#   ifdef STACKBOTTOM
+	return(STACKBOTTOM);
+#   else
+#	ifdef HEURISTIC1
+#	   ifdef STACK_GROWS_DOWN
+	     result = (ptr_t)((((word)(&dummy))
+	     		       + STACKBOTTOM_ALIGNMENT_M1)
+			      & ~STACKBOTTOM_ALIGNMENT_M1);
+#	   else
+	     result = (ptr_t)(((word)(&dummy))
+			      & ~STACKBOTTOM_ALIGNMENT_M1);
+#	   endif
+#	endif /* HEURISTIC1 */
+#	ifdef HEURISTIC2
+#	    ifdef STACK_GROWS_DOWN
+		result = GC_find_limit((ptr_t)(&dummy), TRUE);
+#           	ifdef HEURISTIC2_LIMIT
+		    if (result > HEURISTIC2_LIMIT
+		        && (ptr_t)(&dummy) < HEURISTIC2_LIMIT) {
+		            result = HEURISTIC2_LIMIT;
+		    }
+#	        endif
+#	    else
+		result = GC_find_limit((ptr_t)(&dummy), FALSE);
+#           	ifdef HEURISTIC2_LIMIT
+		    if (result < HEURISTIC2_LIMIT
+		        && (ptr_t)(&dummy) > HEURISTIC2_LIMIT) {
+		            result = HEURISTIC2_LIMIT;
+		    }
+#	        endif
+#	    endif
+
+#	endif /* HEURISTIC2 */
+#	ifdef STACK_GROWS_DOWN
+	    if (result == 0) result = (ptr_t)(signed_word)(-sizeof(ptr_t));
+#	endif
+    	return(result);
+#   endif /* STACKBOTTOM */
+}
+
+# endif /* ! AMIGA */
+# endif /* ! OS2 */
+# endif /* ! MSWIN32 */
+
+/*
+ * Register static data segment(s) as roots.
+ * If more data segments are added later then they need to be registered
+ * add that point (as we do with SunOS dynamic loading),
+ * or GC_mark_roots needs to check for them (as we do with PCR).
+ * Called with allocator lock held.
+ */
+
+# ifdef OS2
+
+void GC_register_data_segments()
+{
+    PTIB ptib;
+    PPIB ppib;
+    HMODULE module_handle;
+#   define PBUFSIZ 512
+    UCHAR path[PBUFSIZ];
+    FILE * myexefile;
+    struct exe_hdr hdrdos;	/* MSDOS header.	*/
+    struct e32_exe hdr386;	/* Real header for my executable */
+    struct o32_obj seg;	/* Currrent segment */
+    int nsegs;
+    
+    
+    if (DosGetInfoBlocks(&ptib, &ppib) != NO_ERROR) {
+    	GC_err_printf0("DosGetInfoBlocks failed\n");
+    	ABORT("DosGetInfoBlocks failed\n");
+    }
+    module_handle = ppib -> pib_hmte;
+    if (DosQueryModuleName(module_handle, PBUFSIZ, path) != NO_ERROR) {
+    	GC_err_printf0("DosQueryModuleName failed\n");
+    	ABORT("DosGetInfoBlocks failed\n");
+    }
+    myexefile = fopen(path, "rb");
+    if (myexefile == 0) {
+        GC_err_puts("Couldn't open executable ");
+        GC_err_puts(path); GC_err_puts("\n");
+        ABORT("Failed to open executable\n");
+    }
+    if (fread((char *)(&hdrdos), 1, sizeof hdrdos, myexefile) < sizeof hdrdos) {
+        GC_err_puts("Couldn't read MSDOS header from ");
+        GC_err_puts(path); GC_err_puts("\n");
+        ABORT("Couldn't read MSDOS header");
+    }
+    if (E_MAGIC(hdrdos) != EMAGIC) {
+        GC_err_puts("Executable has wrong DOS magic number: ");
+        GC_err_puts(path); GC_err_puts("\n");
+        ABORT("Bad DOS magic number");
+    }
+    if (fseek(myexefile, E_LFANEW(hdrdos), SEEK_SET) != 0) {
+        GC_err_puts("Seek to new header failed in ");
+        GC_err_puts(path); GC_err_puts("\n");
+        ABORT("Bad DOS magic number");
+    }
+    if (fread((char *)(&hdr386), 1, sizeof hdr386, myexefile) < sizeof hdr386) {
+        GC_err_puts("Couldn't read MSDOS header from ");
+        GC_err_puts(path); GC_err_puts("\n");
+        ABORT("Couldn't read OS/2 header");
+    }
+    if (E32_MAGIC1(hdr386) != E32MAGIC1 || E32_MAGIC2(hdr386) != E32MAGIC2) {
+        GC_err_puts("Executable has wrong OS/2 magic number:");
+        GC_err_puts(path); GC_err_puts("\n");
+        ABORT("Bad OS/2 magic number");
+    }
+    if ( E32_BORDER(hdr386) != E32LEBO || E32_WORDER(hdr386) != E32LEWO) {
+        GC_err_puts("Executable %s has wrong byte order: ");
+        GC_err_puts(path); GC_err_puts("\n");
+        ABORT("Bad byte order");
+    }
+    if ( E32_CPU(hdr386) == E32CPU286) {
+        GC_err_puts("GC can't handle 80286 executables: ");
+        GC_err_puts(path); GC_err_puts("\n");
+        EXIT();
+    }
+    if (fseek(myexefile, E_LFANEW(hdrdos) + E32_OBJTAB(hdr386),
+    	      SEEK_SET) != 0) {
+        GC_err_puts("Seek to object table failed: ");
+        GC_err_puts(path); GC_err_puts("\n");
+        ABORT("Seek to object table failed");
+    }
+    for (nsegs = E32_OBJCNT(hdr386); nsegs > 0; nsegs--) {
+      int flags;
+      if (fread((char *)(&seg), 1, sizeof seg, myexefile) < sizeof seg) {
+        GC_err_puts("Couldn't read obj table entry from ");
+        GC_err_puts(path); GC_err_puts("\n");
+        ABORT("Couldn't read obj table entry");
+      }
+      flags = O32_FLAGS(seg);
+      if (!(flags & OBJWRITE)) continue;
+      if (!(flags & OBJREAD)) continue;
+      if (flags & OBJINVALID) {
+          GC_err_printf0("Object with invalid pages?\n");
+          continue;
+      } 
+      GC_add_roots_inner(O32_BASE(seg), O32_BASE(seg)+O32_SIZE(seg), FALSE);
+    }
+}
+
+# else
+
+# ifdef MSWIN32
+  /* Unfortunately, we have to handle win32s very differently from NT, 	*/
+  /* Since VirtualQuery has very different semantics.  In particular,	*/
+  /* under win32s a VirtualQuery call on an unmapped page returns an	*/
+  /* invalid result.  Under GC_register_data_segments is a noop and	*/
+  /* all real work is done by GC_register_dynamic_libraries.  Under	*/
+  /* win32s, we cannot find the data segments associated with dll's.	*/
+  /* We rgister the main data segment here.				*/
+  GC_bool GC_win32s = FALSE;	/* We're running under win32s.	*/
+  
+  GC_bool GC_is_win32s()
+  {
+      DWORD v = GetVersion();
+      
+      /* Check that this is not NT, and Windows major version <= 3	*/
+      return ((v & 0x80000000) && (v & 0xff) <= 3);
+  }
+  
+  void GC_init_win32()
+  {
+      GC_win32s = GC_is_win32s();
+  }
+  
+  /* Return the smallest address a such that VirtualQuery		*/
+  /* returns correct results for all addresses between a and start.	*/
+  /* Assumes VirtualQuery returns correct information for start.	*/
+  ptr_t GC_least_described_address(ptr_t start)
+  {  
+    MEMORY_BASIC_INFORMATION buf;
+    SYSTEM_INFO sysinfo;
+    DWORD result;
+    LPVOID limit;
+    ptr_t p;
+    LPVOID q;
+    
+    GetSystemInfo(&sysinfo);
+    limit = sysinfo.lpMinimumApplicationAddress;
+    p = (ptr_t)((word)start & ~(GC_page_size - 1));
+    for (;;) {
+    	q = (LPVOID)(p - GC_page_size);
+    	if ((ptr_t)q > (ptr_t)p /* underflow */ || q < limit) break;
+    	result = VirtualQuery(q, &buf, sizeof(buf));
+    	if (result != sizeof(buf) || buf.AllocationBase == 0) break;
+    	p = (ptr_t)(buf.AllocationBase);
+    }
+    return(p);
+  }
+  
+  /* Is p the start of either the malloc heap, or of one of our */
+  /* heap sections?						*/
+  GC_bool GC_is_heap_base (ptr_t p)
+  {
+     
+     register unsigned i;
+     
+#    ifndef REDIRECT_MALLOC
+       static ptr_t malloc_heap_pointer = 0;
+     
+       if (0 == malloc_heap_pointer) {
+         MEMORY_BASIC_INFORMATION buf;
+         register DWORD result = VirtualQuery(malloc(1), &buf, sizeof(buf));
+         
+         if (result != sizeof(buf)) {
+             ABORT("Weird VirtualQuery result");
+         }
+         malloc_heap_pointer = (ptr_t)(buf.AllocationBase);
+       }
+       if (p == malloc_heap_pointer) return(TRUE);
+#    endif
+     for (i = 0; i < GC_n_heap_bases; i++) {
+         if (GC_heap_bases[i] == p) return(TRUE);
+     }
+     return(FALSE);
+  }
+  
+  void GC_register_root_section(ptr_t static_root)
+  {
+      MEMORY_BASIC_INFORMATION buf;
+      SYSTEM_INFO sysinfo;
+      DWORD result;
+      DWORD protect;
+      LPVOID p;
+      char * base;
+      char * limit, * new_limit;
+    
+      if (!GC_win32s) return;
+      p = base = limit = GC_least_described_address(static_root);
+      GetSystemInfo(&sysinfo);
+      while (p < sysinfo.lpMaximumApplicationAddress) {
+        result = VirtualQuery(p, &buf, sizeof(buf));
+        if (result != sizeof(buf) || buf.AllocationBase == 0
+            || GC_is_heap_base(buf.AllocationBase)) break;
+        new_limit = (char *)p + buf.RegionSize;
+        protect = buf.Protect;
+        if (buf.State == MEM_COMMIT
+            && is_writable(protect)) {
+            if ((char *)p == limit) {
+                limit = new_limit;
+            } else {
+                if (base != limit) GC_add_roots_inner(base, limit, FALSE);
+                base = p;
+                limit = new_limit;
+            }
+        }
+        if (p > (LPVOID)new_limit /* overflow */) break;
+        p = (LPVOID)new_limit;
+      }
+      if (base != limit) GC_add_roots_inner(base, limit, FALSE);
+  }
+  
+  void GC_register_data_segments()
+  {
+      static char dummy;
+      
+      GC_register_root_section((ptr_t)(&dummy));
+  }
+# else
+# ifdef AMIGA
+
+   void GC_register_data_segments()
+   {
+     struct Process	*proc;
+     struct CommandLineInterface *cli;
+     BPTR myseglist;
+     ULONG *data;
+ 
+     int	num;
+
+
+#    ifdef __GNUC__
+        ULONG dataSegSize;
+        GC_bool found_segment = FALSE;
+	extern char __data_size[];
+
+	dataSegSize=__data_size+8;
+	/* Can`t find the Location of __data_size, because
+           it`s possible that is it, inside the segment. */
+
+#     endif
+
+	proc= (struct Process*)SysBase->ThisTask;
+
+	/* Reference: Amiga Guru Book Pages: 538ff,565,573
+		     and XOper.asm */
+	if (proc->pr_Task.tc_Node.ln_Type==NT_PROCESS) {
+	  if (proc->pr_CLI == NULL) {
+	    myseglist = proc->pr_SegList;
+	  } else {
+	    /* ProcLoaded	'Loaded as a command: '*/
+	    cli = BADDR(proc->pr_CLI);
+	    myseglist = cli->cli_Module;
+	  }
+	} else {
+	  ABORT("Not a Process.");
+ 	}
+
+	if (myseglist == NULL) {
+	    ABORT("Arrrgh.. can't find segments, aborting");
+ 	}
+
+	/* xoper hunks Shell Process */
+
+	num=0;
+        for (data = (ULONG *)BADDR(myseglist); data != NULL;
+             data = (ULONG *)BADDR(data[0])) {
+	  if (((ULONG) GC_register_data_segments < (ULONG) &data[1]) ||
+	      ((ULONG) GC_register_data_segments > (ULONG) &data[1] + data[-1])) {
+#             ifdef __GNUC__
+		if (dataSegSize == data[-1]) {
+		  found_segment = TRUE;
+		}
+# 	      endif
+	      GC_add_roots_inner((char *)&data[1],
+				 ((char *)&data[1]) + data[-1], FALSE);
+          }
+          ++num;
+        } /* for */
+# 	ifdef __GNUC__
+	   if (!found_segment) {
+	     ABORT("Can`t find correct Segments.\nSolution: Use an newer version of ixemul.library");
+	   }
+# 	endif
+  }
+
+#if 0 /* old version */
+  void GC_register_data_segments()
+  {
+    extern struct WBStartup *_WBenchMsg;
+    struct Process	*proc;
+    struct CommandLineInterface *cli;
+    BPTR myseglist;
+    ULONG *data;
+
+    if ( _WBenchMsg != 0 ) {
+	if ((myseglist = _WBenchMsg->sm_Segment) == 0) {
+	    GC_err_puts("No seglist from workbench\n");
+	    return;
+	}
+    } else {
+	if ((proc = (struct Process *)FindTask(0)) == 0) {
+	    GC_err_puts("Cannot find process structure\n");
+	    return;
+	}
+	if ((cli = BADDR(proc->pr_CLI)) == 0) {
+	    GC_err_puts("No CLI\n");
+	    return;
+	}
+	if ((myseglist = cli->cli_Module) == 0) {
+	    GC_err_puts("No seglist from CLI\n");
+	    return;
+	}
+    }
+
+    for (data = (ULONG *)BADDR(myseglist); data != 0;
+         data = (ULONG *)BADDR(data[0])) {
+#        ifdef AMIGA_SKIP_SEG
+           if (((ULONG) GC_register_data_segments < (ULONG) &data[1]) ||
+           ((ULONG) GC_register_data_segments > (ULONG) &data[1] + data[-1])) {
+#	 else
+      	   {
+#	 endif /* AMIGA_SKIP_SEG */
+          GC_add_roots_inner((char *)&data[1],
+          		     ((char *)&data[1]) + data[-1], FALSE);
+         }
+    }
+  }
+#endif /* old version */
+
+
+# else
+
+# if (defined(SVR4) || defined(AUX) || defined(DGUX)) && !defined(PCR)
+char * GC_SysVGetDataStart(max_page_size, etext_addr)
+int max_page_size;
+int * etext_addr;
+{
+    word text_end = ((word)(etext_addr) + sizeof(word) - 1)
+    		    & ~(sizeof(word) - 1);
+    	/* etext rounded to word boundary	*/
+    word next_page = ((text_end + (word)max_page_size - 1)
+    		      & ~((word)max_page_size - 1));
+    word page_offset = (text_end & ((word)max_page_size - 1));
+    VOLATILE char * result = (char *)(next_page + page_offset);
+    /* Note that this isnt equivalent to just adding		*/
+    /* max_page_size to &etext if &etext is at a page boundary	*/
+    
+    GC_setup_temporary_fault_handler();
+    if (setjmp(GC_jmp_buf) == 0) {
+    	/* Try writing to the address.	*/
+    	*result = *result;
+        GC_reset_fault_handler();
+    } else {
+        GC_reset_fault_handler();
+    	/* We got here via a longjmp.  The address is not readable.	*/
+    	/* This is known to happen under Solaris 2.4 + gcc, which place	*/
+    	/* string constants in the text segment, but after etext.	*/
+    	/* Use plan B.  Note that we now know there is a gap between	*/
+    	/* text and data segments, so plan A bought us something.	*/
+    	result = (char *)GC_find_limit((ptr_t)(DATAEND) - MIN_PAGE_SIZE, FALSE);
+    }
+    return((char *)result);
+}
+# endif
+
+
+void GC_register_data_segments()
+{
+#   if !defined(PCR) && !defined(SRC_M3) && !defined(NEXT) && !defined(MACOS) \
+       && !defined(MACOSX)
+#     if defined(REDIRECT_MALLOC) && defined(SOLARIS_THREADS)
+	/* As of Solaris 2.3, the Solaris threads implementation	*/
+	/* allocates the data structure for the initial thread with	*/
+	/* sbrk at process startup.  It needs to be scanned, so that	*/
+	/* we don't lose some malloc allocated data structures		*/
+	/* hanging from it.  We're on thin ice here ...			*/
+        extern caddr_t sbrk();
+
+	GC_add_roots_inner(DATASTART, (char *)sbrk(0), FALSE);
+#     else
+	GC_add_roots_inner(DATASTART, (char *)(DATAEND), FALSE);
+#     endif
+#   endif
+#   if !defined(PCR) && (defined(NEXT) || defined(MACOSX))
+      GC_add_roots_inner(DATASTART, (char *) get_end(), FALSE);
+#   endif
+#   if defined(MACOS)
+    {
+#   if defined(THINK_C)
+	extern void* GC_MacGetDataStart(void);
+	/* globals begin above stack and end at a5. */
+	GC_add_roots_inner((ptr_t)GC_MacGetDataStart(),
+			   (ptr_t)LMGetCurrentA5(), FALSE);
+#   else
+#     if defined(__MWERKS__)
+#       if !__POWERPC__
+	  extern void* GC_MacGetDataStart(void);
+	  /* MATTHEW: Function to handle Far Globals (CW Pro 3) */
+#         if __option(far_data)
+	  extern void* GC_MacGetDataEnd(void);
+#         endif
+	  /* globals begin above stack and end at a5. */
+	  GC_add_roots_inner((ptr_t)GC_MacGetDataStart(),
+          		     (ptr_t)LMGetCurrentA5(), FALSE);
+	  /* MATTHEW: Handle Far Globals */          		     
+#         if __option(far_data)
+      /* Far globals follow he QD globals: */
+	  GC_add_roots_inner((ptr_t)LMGetCurrentA5(),
+          		     (ptr_t)GC_MacGetDataEnd(), FALSE);
+#         endif
+#       else
+	  extern char __data_start__[], __data_end__[];
+	  GC_add_roots_inner((ptr_t)&__data_start__,
+	  		     (ptr_t)&__data_end__, FALSE);
+#       endif /* __POWERPC__ */
+#     endif /* __MWERKS__ */
+#   endif /* !THINK_C */
+    }
+#   endif /* MACOS */
+
+    /* Dynamic libraries are added at every collection, since they may  */
+    /* change.								*/
+}
+
+# endif  /* ! AMIGA */
+# endif  /* ! MSWIN32 */
+# endif  /* ! OS2 */
+
+/*
+ * Auxiliary routines for obtaining memory from OS.
+ */
+ 
+# if !defined(OS2) && !defined(PCR) && !defined(AMIGA) \
+	&& !defined(MSWIN32) && !defined(MACOS) && !defined(DOS4GW)
+
+# ifdef SUNOS4
+    extern caddr_t sbrk();
+# endif
+# ifdef __STDC__
+#   define SBRK_ARG_T ptrdiff_t
+# else
+#   define SBRK_ARG_T int
+# endif
+
+# ifdef RS6000
+/* The compiler seems to generate speculative reads one past the end of	*/
+/* an allocated object.  Hence we need to make sure that the page 	*/
+/* following the last heap page is also mapped.				*/
+ptr_t GC_unix_get_mem(bytes)
+word bytes;
+{
+    caddr_t cur_brk = (caddr_t)sbrk(0);
+    caddr_t result;
+    SBRK_ARG_T lsbs = (word)cur_brk & (GC_page_size-1);
+    static caddr_t my_brk_val = 0;
+    
+    if ((SBRK_ARG_T)bytes < 0) return(0); /* too big */
+    if (lsbs != 0) {
+        if((caddr_t)(sbrk(GC_page_size - lsbs)) == (caddr_t)(-1)) return(0);
+    }
+    if (cur_brk == my_brk_val) {
+    	/* Use the extra block we allocated last time. */
+        result = (ptr_t)sbrk((SBRK_ARG_T)bytes);
+        if (result == (caddr_t)(-1)) return(0);
+        result -= GC_page_size;
+    } else {
+        result = (ptr_t)sbrk(GC_page_size + (SBRK_ARG_T)bytes);
+        if (result == (caddr_t)(-1)) return(0);
+    }
+    my_brk_val = result + bytes + GC_page_size;	/* Always page aligned */
+    return((ptr_t)result);
+}
+
+#else  /* Not RS6000 */
+
+#if defined(USE_MMAP)
+/* Tested only under IRIX5 and Solaris 2 */
+
+#ifdef USE_MMAP_FIXED
+#   define GC_MMAP_FLAGS MAP_FIXED | MAP_PRIVATE
+	/* Seems to yield better performance on Solaris 2, but can	*/
+	/* be unreliable if something is already mapped at the address.	*/
+#else
+#   define GC_MMAP_FLAGS MAP_PRIVATE
+#endif
+
+ptr_t GC_unix_get_mem(bytes)
+word bytes;
+{
+    static GC_bool initialized = FALSE;
+    static int fd;
+    void *result;
+    static ptr_t last_addr = HEAP_START;
+
+    if (!initialized) {
+	fd = open("/dev/zero", O_RDONLY);
+	initialized = TRUE;
+    }
+    if (bytes & (GC_page_size -1)) ABORT("Bad GET_MEM arg");
+    result = mmap(last_addr, bytes, PROT_READ | PROT_WRITE | OPT_PROT_EXEC,
+		  GC_MMAP_FLAGS, fd, 0/* offset */);
+    if (result == MAP_FAILED) return(0);
+    last_addr = (ptr_t)result + bytes + GC_page_size - 1;
+    last_addr = (ptr_t)((word)last_addr & ~(GC_page_size - 1));
+    return((ptr_t)result);
+}
+
+#else /* Not RS6000, not USE_MMAP */
+ptr_t GC_unix_get_mem(bytes)
+word bytes;
+{
+  ptr_t result;
+# ifdef IRIX5
+    /* Bare sbrk isn't thread safe.  Play by malloc rules.	*/
+    /* The equivalent may be needed on other systems as well. 	*/
+    __LOCK_MALLOC();
+# endif
+  {
+    ptr_t cur_brk = (ptr_t)sbrk(0);
+    SBRK_ARG_T lsbs = (word)cur_brk & (GC_page_size-1);
+    
+    if ((SBRK_ARG_T)bytes < 0) return(0); /* too big */
+    if (lsbs != 0) {
+        if((ptr_t)sbrk(GC_page_size - lsbs) == (ptr_t)(-1)) return(0);
+    }
+    result = (ptr_t)sbrk((SBRK_ARG_T)bytes);
+    if (result == (ptr_t)(-1)) result = 0;
+  }
+# ifdef IRIX5
+    __UNLOCK_MALLOC();
+# endif
+  return(result);
+}
+
+#endif /* Not USE_MMAP */
+#endif /* Not RS6000 */
+
+# endif /* UN*X */
+
+# ifdef OS2
+
+void * os2_alloc(size_t bytes)
+{
+    void * result;
+
+    if (DosAllocMem(&result, bytes, PAG_EXECUTE | PAG_READ |
+    				    PAG_WRITE | PAG_COMMIT)
+		    != NO_ERROR) {
+	return(0);
+    }
+    if (result == 0) return(os2_alloc(bytes));
+    return(result);
+}
+
+# endif /* OS2 */
+
+
+# ifdef MSWIN32
+word GC_n_heap_bases = 0;
+
+ptr_t GC_win32_get_mem(bytes)
+word bytes;
+{
+    ptr_t result;
+    
+    if (GC_win32s) {
+    	/* VirtualAlloc doesn't like PAGE_EXECUTE_READWRITE.	*/
+    	/* There are also unconfirmed rumors of other		*/
+    	/* problems, so we dodge the issue.			*/
+        result = (ptr_t) GlobalAlloc(0, bytes + HBLKSIZE);
+        result = (ptr_t)(((word)result + HBLKSIZE) & ~(HBLKSIZE-1));
+    } else {
+        result = (ptr_t) VirtualAlloc(NULL, bytes,
+    				      MEM_COMMIT | MEM_RESERVE,
+    				      PAGE_EXECUTE_READWRITE);
+    }
+    if (HBLKDISPL(result) != 0) ABORT("Bad VirtualAlloc result");
+    	/* If I read the documentation correctly, this can	*/
+    	/* only happen if HBLKSIZE > 64k or not a power of 2.	*/
+    if (GC_n_heap_bases >= MAX_HEAP_SECTS) ABORT("Too many heap sections");
+    GC_heap_bases[GC_n_heap_bases++] = result;
+    return(result);			  
+}
+
+void GC_win32_free_heap ()
+{
+    if (GC_win32s) {
+ 	while (GC_n_heap_bases > 0) {
+ 	    GlobalFree (GC_heap_bases[--GC_n_heap_bases]);
+ 	    GC_heap_bases[GC_n_heap_bases] = 0;
+ 	}
+    }
+}
+
+
+# endif
+
+#ifdef USE_MUNMAP
+
+/* For now, this only works on some Unix-like systems.  If you 	*/
+/* have something else, don't define USE_MUNMAP.		*/
+/* We assume ANSI C to support this feature.			*/
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+
+/* Compute a page aligned starting address for the unmap 	*/
+/* operation on a block of size bytes starting at start.	*/
+/* Return 0 if the block is too small to make this feasible.	*/
+ptr_t GC_unmap_start(ptr_t start, word bytes)
+{
+    ptr_t result = start;
+    /* Round start to next page boundary.       */
+        result += GC_page_size - 1;
+        result = (ptr_t)((word)result & ~(GC_page_size - 1));
+    if (result + GC_page_size > start + bytes) return 0;
+    return result;
+}
+
+/* Compute end address for an unmap operation on the indicated	*/
+/* block.							*/
+ptr_t GC_unmap_end(ptr_t start, word bytes)
+{
+    ptr_t end_addr = start + bytes;
+    end_addr = (ptr_t)((word)end_addr & ~(GC_page_size - 1));
+    return end_addr;
+}
+
+/* We assume that GC_remap is called on exactly the same range	*/
+/* as a previous call to GC_unmap.  It is safe to consistently	*/
+/* round the endpoints in both places.				*/
+void GC_unmap(ptr_t start, word bytes)
+{
+    ptr_t start_addr = GC_unmap_start(start, bytes);
+    ptr_t end_addr = GC_unmap_end(start, bytes);
+    word len = end_addr - start_addr;
+    if (0 == start_addr) return;
+    if (munmap(start_addr, len) != 0) ABORT("munmap failed");
+    GC_unmapped_bytes += len;
+}
+
+
+void GC_remap(ptr_t start, word bytes)
+{
+    static int zero_descr = -1;
+    ptr_t start_addr = GC_unmap_start(start, bytes);
+    ptr_t end_addr = GC_unmap_end(start, bytes);
+    word len = end_addr - start_addr;
+    ptr_t result;
+
+    if (-1 == zero_descr) zero_descr = open("/dev/zero", O_RDWR);
+    if (0 == start_addr) return;
+    result = mmap(start_addr, len, PROT_READ | PROT_WRITE | OPT_PROT_EXEC,
+	          MAP_FIXED | MAP_PRIVATE, zero_descr, 0);
+    if (result != start_addr) {
+	ABORT("mmap remapping failed");
+    }
+    GC_unmapped_bytes -= len;
+}
+
+/* Two adjacent blocks have already been unmapped and are about to	*/
+/* be merged.  Unmap the whole block.  This typically requires		*/
+/* that we unmap a small section in the middle that was not previously	*/
+/* unmapped due to alignment constraints.				*/
+void GC_unmap_gap(ptr_t start1, word bytes1, ptr_t start2, word bytes2)
+{
+    ptr_t start1_addr = GC_unmap_start(start1, bytes1);
+    ptr_t end1_addr = GC_unmap_end(start1, bytes1);
+    ptr_t start2_addr = GC_unmap_start(start2, bytes2);
+    ptr_t end2_addr = GC_unmap_end(start2, bytes2);
+    ptr_t start_addr = end1_addr;
+    ptr_t end_addr = start2_addr;
+    word len;
+    GC_ASSERT(start1 + bytes1 == start2);
+    if (0 == start1_addr) start_addr = GC_unmap_start(start1, bytes1 + bytes2);
+    if (0 == start2_addr) end_addr = GC_unmap_end(start1, bytes1 + bytes2);
+    if (0 == start_addr) return;
+    len = end_addr - start_addr;
+    if (len != 0 && munmap(start_addr, len) != 0) ABORT("munmap failed");
+    GC_unmapped_bytes += len;
+}
+
+#endif /* USE_MUNMAP */
+
+/* Routine for pushing any additional roots.  In THREADS 	*/
+/* environment, this is also responsible for marking from 	*/
+/* thread stacks.  In the SRC_M3 case, it also handles		*/
+/* global variables.						*/
+#ifndef THREADS
+void (*GC_push_other_roots)() = 0;
+#else /* THREADS */
+
+# ifdef PCR
+PCR_ERes GC_push_thread_stack(PCR_Th_T *t, PCR_Any dummy)
+{
+    struct PCR_ThCtl_TInfoRep info;
+    PCR_ERes result;
+    
+    info.ti_stkLow = info.ti_stkHi = 0;
+    result = PCR_ThCtl_GetInfo(t, &info);
+    GC_push_all_stack((ptr_t)(info.ti_stkLow), (ptr_t)(info.ti_stkHi));
+    return(result);
+}
+
+/* Push the contents of an old object. We treat this as stack	*/
+/* data only becasue that makes it robust against mark stack	*/
+/* overflow.							*/
+PCR_ERes GC_push_old_obj(void *p, size_t size, PCR_Any data)
+{
+    GC_push_all_stack((ptr_t)p, (ptr_t)p + size);
+    return(PCR_ERes_okay);
+}
+
+
+void GC_default_push_other_roots()
+{
+    /* Traverse data allocated by previous memory managers.		*/
+	{
+	  extern struct PCR_MM_ProcsRep * GC_old_allocator;
+	  
+	  if ((*(GC_old_allocator->mmp_enumerate))(PCR_Bool_false,
+	  					   GC_push_old_obj, 0)
+	      != PCR_ERes_okay) {
+	      ABORT("Old object enumeration failed");
+	  }
+	}
+    /* Traverse all thread stacks. */
+	if (PCR_ERes_IsErr(
+                PCR_ThCtl_ApplyToAllOtherThreads(GC_push_thread_stack,0))
+              || PCR_ERes_IsErr(GC_push_thread_stack(PCR_Th_CurrThread(), 0))) {
+              ABORT("Thread stack marking failed\n");
+	}
+}
+
+# endif /* PCR */
+
+# ifdef SRC_M3
+
+# ifdef ALL_INTERIOR_POINTERS
+    --> misconfigured
+# endif
+
+
+extern void ThreadF__ProcessStacks();
+
+void GC_push_thread_stack(start, stop)
+word start, stop;
+{
+   GC_push_all_stack((ptr_t)start, (ptr_t)stop + sizeof(word));
+}
+
+/* Push routine with M3 specific calling convention. */
+GC_m3_push_root(dummy1, p, dummy2, dummy3)
+word *p;
+ptr_t dummy1, dummy2;
+int dummy3;
+{
+    word q = *p;
+    
+    if ((ptr_t)(q) >= GC_least_plausible_heap_addr
+	 && (ptr_t)(q) < GC_greatest_plausible_heap_addr) {
+	 GC_push_one_checked(q,FALSE);
+    }
+}
+
+/* M3 set equivalent to RTHeap.TracedRefTypes */
+typedef struct { int elts[1]; }  RefTypeSet;
+RefTypeSet GC_TracedRefTypes = {{0x1}};
+
+/* From finalize.c */
+extern void GC_push_finalizer_structures();
+
+/* From stubborn.c: */
+# ifdef STUBBORN_ALLOC
+    extern GC_PTR * GC_changing_list_start;
+# endif
+
+
+void GC_default_push_other_roots()
+{
+    /* Use the M3 provided routine for finding static roots.	*/
+    /* This is a bit dubious, since it presumes no C roots.	*/
+    /* We handle the collector roots explicitly.		*/
+       {
+# 	 ifdef STUBBORN_ALLOC
+           GC_push_one(GC_changing_list_start);
+#	 endif
+      	 GC_push_finalizer_structures();
+      	 RTMain__GlobalMapProc(GC_m3_push_root, 0, GC_TracedRefTypes);
+       }
+	if (GC_words_allocd > 0) {
+	    ThreadF__ProcessStacks(GC_push_thread_stack);
+	}
+	/* Otherwise this isn't absolutely necessary, and we have	*/
+	/* startup ordering problems.					*/
+}
+
+# endif /* SRC_M3 */
+
+# if defined(SOLARIS_THREADS) || defined(WIN32_THREADS) \
+     || defined(IRIX_THREADS) || defined(LINUX_THREADS) \
+     || defined(IRIX_PCR_THREADS)
+
+extern void GC_push_all_stacks();
+
+void GC_default_push_other_roots()
+{
+    GC_push_all_stacks();
+}
+
+# endif /* SOLARIS_THREADS || ... */
+
+void (*GC_push_other_roots)() = GC_default_push_other_roots;
+
+#endif
+
+/*
+ * Routines for accessing dirty  bits on virtual pages.
+ * We plan to eventaually implement four strategies for doing so:
+ * DEFAULT_VDB:	A simple dummy implementation that treats every page
+ *		as possibly dirty.  This makes incremental collection
+ *		useless, but the implementation is still correct.
+ * PCR_VDB:	Use PPCRs virtual dirty bit facility.
+ * PROC_VDB:	Use the /proc facility for reading dirty bits.  Only
+ *		works under some SVR4 variants.  Even then, it may be
+ *		too slow to be entirely satisfactory.  Requires reading
+ *		dirty bits for entire address space.  Implementations tend
+ *		to assume that the client is a (slow) debugger.
+ * MPROTECT_VDB:Protect pages and then catch the faults to keep track of
+ *		dirtied pages.  The implementation (and implementability)
+ *		is highly system dependent.  This usually fails when system
+ *		calls write to a protected page.  We prevent the read system
+ *		call from doing so.  It is the clients responsibility to
+ *		make sure that other system calls are similarly protected
+ *		or write only to the stack.
+ */
+ 
+GC_bool GC_dirty_maintained = FALSE;
+
+# ifdef DEFAULT_VDB
+
+/* All of the following assume the allocation lock is held, and	*/
+/* signals are disabled.					*/
+
+/* The client asserts that unallocated pages in the heap are never	*/
+/* written.								*/
+
+/* Initialize virtual dirty bit implementation.			*/
+void GC_dirty_init()
+{
+    GC_dirty_maintained = TRUE;
+}
+
+/* Retrieve system dirty bits for heap to a local buffer.	*/
+/* Restore the systems notion of which pages are dirty.		*/
+void GC_read_dirty()
+{}
+
+/* Is the HBLKSIZE sized page at h marked dirty in the local buffer?	*/
+/* If the actual page size is different, this returns TRUE if any	*/
+/* of the pages overlapping h are dirty.  This routine may err on the	*/
+/* side of labelling pages as dirty (and this implementation does).	*/
+/*ARGSUSED*/
+GC_bool GC_page_was_dirty(h)
+struct hblk *h;
+{
+    return(TRUE);
+}
+
+/*
+ * The following two routines are typically less crucial.  They matter
+ * most with large dynamic libraries, or if we can't accurately identify
+ * stacks, e.g. under Solaris 2.X.  Otherwise the following default
+ * versions are adequate.
+ */
+ 
+/* Could any valid GC heap pointer ever have been written to this page?	*/
+/*ARGSUSED*/
+GC_bool GC_page_was_ever_dirty(h)
+struct hblk *h;
+{
+    return(TRUE);
+}
+
+/* Reset the n pages starting at h to "was never dirty" status.	*/
+void GC_is_fresh(h, n)
+struct hblk *h;
+word n;
+{
+}
+
+/* A call hints that h is about to be written.	*/
+/* May speed up some dirty bit implementations.	*/
+/*ARGSUSED*/
+void GC_write_hint(h)
+struct hblk *h;
+{
+}
+
+# endif /* DEFAULT_VDB */
+
+
+# ifdef MPROTECT_VDB
+
+/*
+ * See DEFAULT_VDB for interface descriptions.
+ */
+
+/*
+ * This implementation maintains dirty bits itself by catching write
+ * faults and keeping track of them.  We assume nobody else catches
+ * SIGBUS or SIGSEGV.  We assume no write faults occur in system calls
+ * except as a result of a read system call.  This means clients must
+ * either ensure that system calls do not touch the heap, or must
+ * provide their own wrappers analogous to the one for read.
+ * We assume the page size is a multiple of HBLKSIZE.
+ * This implementation is currently SunOS 4.X and IRIX 5.X specific, though we
+ * tried to use portable code where easily possible.  It is known
+ * not to work under a number of other systems.
+ */
+
+# ifndef MSWIN32
+
+#   include <sys/mman.h>
+#   include <signal.h>
+#   include <sys/syscall.h>
+
+#   define PROTECT(addr, len) \
+    	  if (mprotect((caddr_t)(addr), (int)(len), \
+    	      	       PROT_READ | OPT_PROT_EXEC) < 0) { \
+    	    ABORT("mprotect failed"); \
+    	  }
+#   define UNPROTECT(addr, len) \
+    	  if (mprotect((caddr_t)(addr), (int)(len), \
+    	  	       PROT_WRITE | PROT_READ | OPT_PROT_EXEC ) < 0) { \
+    	    ABORT("un-mprotect failed"); \
+    	  }
+    	  
+# else
+
+#   include <signal.h>
+
+    static DWORD protect_junk;
+#   define PROTECT(addr, len) \
+	  if (!VirtualProtect((addr), (len), PAGE_EXECUTE_READ, \
+	  		      &protect_junk)) { \
+	    DWORD last_error = GetLastError(); \
+	    GC_printf1("Last error code: %lx\n", last_error); \
+	    ABORT("VirtualProtect failed"); \
+	  }
+#   define UNPROTECT(addr, len) \
+	  if (!VirtualProtect((addr), (len), PAGE_EXECUTE_READWRITE, \
+	  		      &protect_junk)) { \
+	    ABORT("un-VirtualProtect failed"); \
+	  }
+	  
+# endif
+
+#if defined(SUNOS4) || defined(FREEBSD)
+    typedef void (* SIG_PF)();
+#endif
+#if defined(SUNOS5SIGS) || defined(OSF1) || defined(LINUX)
+    typedef void (* SIG_PF)(int);
+#endif
+#if defined(MSWIN32)
+    typedef LPTOP_LEVEL_EXCEPTION_FILTER SIG_PF;
+#   undef SIG_DFL
+#   define SIG_DFL (LPTOP_LEVEL_EXCEPTION_FILTER) (-1)
+#endif
+
+#if defined(IRIX5) || defined(OSF1)
+    typedef void (* REAL_SIG_PF)(int, int, struct sigcontext *);
+#endif
+#if defined(SUNOS5SIGS)
+    typedef void (* REAL_SIG_PF)(int, struct siginfo *, void *);
+#endif
+#if defined(LINUX)
+#   include <linux/version.h>
+#   if (LINUX_VERSION_CODE >= 0x20100) && !defined(M68K) || defined(ALPHA)
+      typedef struct sigcontext s_c;
+#   else
+      typedef struct sigcontext_struct s_c;
+#   endif
+#   ifdef ALPHA
+    typedef void (* REAL_SIG_PF)(int, int, s_c *);
+    /* Retrieve fault address from sigcontext structure by decoding	*/
+    /* instruction.							*/
+    char * get_fault_addr(s_c *sc) {
+        unsigned instr;
+	word faultaddr;
+
+	instr = *((unsigned *)(sc->sc_pc));
+	faultaddr = sc->sc_regs[(instr >> 16) & 0x1f];
+	faultaddr += (word) (((int)instr << 16) >> 16);
+	return (char *)faultaddr;
+    }
+#   else /* !ALPHA */
+    typedef void (* REAL_SIG_PF)(int, s_c);
+#   endif /* !ALPHA */
+# endif
+
+SIG_PF GC_old_bus_handler;
+SIG_PF GC_old_segv_handler;	/* Also old MSWIN32 ACCESS_VIOLATION filter */
+
+/*ARGSUSED*/
+# if defined (SUNOS4) || defined(FREEBSD)
+    void GC_write_fault_handler(sig, code, scp, addr)
+    int sig, code;
+    struct sigcontext *scp;
+    char * addr;
+#   ifdef SUNOS4
+#     define SIG_OK (sig == SIGSEGV || sig == SIGBUS)
+#     define CODE_OK (FC_CODE(code) == FC_PROT \
+              	    || (FC_CODE(code) == FC_OBJERR \
+              	       && FC_ERRNO(code) == FC_PROT))
+#   endif
+#   ifdef FREEBSD
+#     define SIG_OK (sig == SIGBUS)
+#     define CODE_OK (code == BUS_PAGE_FAULT)
+#   endif
+# endif
+# if defined(IRIX5) || defined(OSF1)
+#   include <errno.h>
+    void GC_write_fault_handler(int sig, int code, struct sigcontext *scp)
+#   define SIG_OK (sig == SIGSEGV)
+#   ifdef OSF1
+#     define CODE_OK (code == 2 /* experimentally determined */)
+#   endif
+#   ifdef IRIX5
+#     define CODE_OK (code == EACCES)
+#   endif
+# endif
+# if defined(LINUX)
+#   ifdef ALPHA
+      void GC_write_fault_handler(int sig, int code, s_c * sc)
+#   else
+      void GC_write_fault_handler(int sig, s_c sc)
+#   endif
+#   define SIG_OK (sig == SIGSEGV)
+#   define CODE_OK TRUE
+	/* Empirically c.trapno == 14, but is that useful?      */
+	/* We assume Intel architecture, so alignment		*/
+	/* faults are not possible.				*/
+# endif
+# if defined(SUNOS5SIGS)
+    void GC_write_fault_handler(int sig, struct siginfo *scp, void * context)
+#   define SIG_OK (sig == SIGSEGV)
+#   define CODE_OK (scp -> si_code == SEGV_ACCERR)
+# endif
+# if defined(MSWIN32)
+    LONG WINAPI GC_write_fault_handler(struct _EXCEPTION_POINTERS *exc_info)
+#   define SIG_OK (exc_info -> ExceptionRecord -> ExceptionCode == \
+			EXCEPTION_ACCESS_VIOLATION)
+#   define CODE_OK (exc_info -> ExceptionRecord -> ExceptionInformation[0] == 1)
+			/* Write fault */
+# endif
+{
+    register unsigned i;
+#   ifdef IRIX5
+	char * addr = (char *) (size_t) (scp -> sc_badvaddr);
+#   endif
+#   if defined(OSF1) && defined(ALPHA)
+	char * addr = (char *) (scp -> sc_traparg_a0);
+#   endif
+#   ifdef SUNOS5SIGS
+	char * addr = (char *) (scp -> si_addr);
+#   endif
+#   ifdef LINUX
+#     ifdef I386
+	char * addr = (char *) (sc.cr2);
+#     else
+#	if defined(M68K)
+          char * addr = NULL;
+
+	  struct sigcontext *scp = (struct sigcontext *)(&sc);
+
+	  int format = (scp->sc_formatvec >> 12) & 0xf;
+	  unsigned long *framedata = (unsigned long *)(scp + 1); 
+	  unsigned long ea;
+
+	  if (format == 0xa || format == 0xb) {
+	  	/* 68020/030 */
+	  	ea = framedata[2];
+	  } else if (format == 7) {
+	  	/* 68040 */
+	  	ea = framedata[3];
+	  } else if (format == 4) {
+	  	/* 68060 */
+	  	ea = framedata[0];
+	  	if (framedata[1] & 0x08000000) {
+	  		/* correct addr on misaligned access */
+	  		ea = (ea+4095)&(~4095);
+	  	}
+	  }	
+	  addr = (char *)ea;
+#	else
+#	  ifdef ALPHA
+            char * addr = get_fault_addr(sc);
+#	  else
+		--> architecture not supported
+#	  endif
+#	endif
+#     endif
+#   endif
+#   if defined(MSWIN32)
+	char * addr = (char *) (exc_info -> ExceptionRecord
+				-> ExceptionInformation[1]);
+#	define sig SIGSEGV
+#   endif
+    
+    if (SIG_OK && CODE_OK) {
+        register struct hblk * h =
+        		(struct hblk *)((word)addr & ~(GC_page_size-1));
+        GC_bool in_allocd_block;
+        
+#	ifdef SUNOS5SIGS
+	    /* Address is only within the correct physical page.	*/
+	    in_allocd_block = FALSE;
+            for (i = 0; i < divHBLKSZ(GC_page_size); i++) {
+              if (HDR(h+i) != 0) {
+                in_allocd_block = TRUE;
+              }
+            }
+#	else
+	    in_allocd_block = (HDR(addr) != 0);
+#	endif
+        if (!in_allocd_block) {
+	    /* Heap blocks now begin and end on page boundaries */
+            SIG_PF old_handler;
+            
+            if (sig == SIGSEGV) {
+            	old_handler = GC_old_segv_handler;
+            } else {
+                old_handler = GC_old_bus_handler;
+            }
+            if (old_handler == SIG_DFL) {
+#		ifndef MSWIN32
+		    GC_err_printf1("Segfault at 0x%lx\n", addr);
+                    ABORT("Unexpected bus error or segmentation fault");
+#		else
+		    return(EXCEPTION_CONTINUE_SEARCH);
+#		endif
+            } else {
+#		if defined (SUNOS4) || defined(FREEBSD)
+		    (*old_handler) (sig, code, scp, addr);
+		    return;
+#		endif
+#		if defined (SUNOS5SIGS)
+		    (*(REAL_SIG_PF)old_handler) (sig, scp, context);
+		    return;
+#		endif
+#		if defined (LINUX)
+#		    ifdef ALPHA
+		        (*(REAL_SIG_PF)old_handler) (sig, code, sc);
+#		    else 
+		        (*(REAL_SIG_PF)old_handler) (sig, sc);
+#		    endif
+		    return;
+#		endif
+#		if defined (IRIX5) || defined(OSF1)
+		    (*(REAL_SIG_PF)old_handler) (sig, code, scp);
+		    return;
+#		endif
+#		ifdef MSWIN32
+		    return((*old_handler)(exc_info));
+#		endif
+            }
+        }
+        for (i = 0; i < divHBLKSZ(GC_page_size); i++) {
+            register int index = PHT_HASH(h+i);
+            
+            set_pht_entry_from_index(GC_dirty_pages, index);
+        }
+        UNPROTECT(h, GC_page_size);
+#	if defined(OSF1) || defined(LINUX)
+	    /* These reset the signal handler each time by default. */
+	    signal(SIGSEGV, (SIG_PF) GC_write_fault_handler);
+#	endif
+    	/* The write may not take place before dirty bits are read.	*/
+    	/* But then we'll fault again ...				*/
+#	ifdef MSWIN32
+	    return(EXCEPTION_CONTINUE_EXECUTION);
+#	else
+	    return;
+#	endif
+    }
+#ifdef MSWIN32
+    return EXCEPTION_CONTINUE_SEARCH;
+#else
+    GC_err_printf1("Segfault at 0x%lx\n", addr);
+    ABORT("Unexpected bus error or segmentation fault");
+#endif
+}
+
+/*
+ * We hold the allocation lock.  We expect block h to be written
+ * shortly.
+ */
+void GC_write_hint(h)
+struct hblk *h;
+{
+    register struct hblk * h_trunc;
+    register unsigned i;
+    register GC_bool found_clean;
+    
+    if (!GC_dirty_maintained) return;
+    h_trunc = (struct hblk *)((word)h & ~(GC_page_size-1));
+    found_clean = FALSE;
+    for (i = 0; i < divHBLKSZ(GC_page_size); i++) {
+        register int index = PHT_HASH(h_trunc+i);
+            
+        if (!get_pht_entry_from_index(GC_dirty_pages, index)) {
+            found_clean = TRUE;
+            set_pht_entry_from_index(GC_dirty_pages, index);
+        }
+    }
+    if (found_clean) {
+    	UNPROTECT(h_trunc, GC_page_size);
+    }
+}
+
+void GC_dirty_init()
+{
+#if defined(SUNOS5SIGS) || defined(IRIX5) /* || defined(OSF1) */
+    struct sigaction	act, oldact;
+#   ifdef IRIX5
+    	act.sa_flags	= SA_RESTART;
+        act.sa_handler  = GC_write_fault_handler;
+#   else
+    	act.sa_flags	= SA_RESTART | SA_SIGINFO;
+        act.sa_sigaction = GC_write_fault_handler;
+#   endif
+    (void)sigemptyset(&act.sa_mask); 
+#endif
+#   ifdef PRINTSTATS
+	GC_printf0("Inititalizing mprotect virtual dirty bit implementation\n");
+#   endif
+    GC_dirty_maintained = TRUE;
+    if (GC_page_size % HBLKSIZE != 0) {
+        GC_err_printf0("Page size not multiple of HBLKSIZE\n");
+        ABORT("Page size not multiple of HBLKSIZE");
+    }
+#   if defined(SUNOS4) || defined(FREEBSD)
+      GC_old_bus_handler = signal(SIGBUS, GC_write_fault_handler);
+      if (GC_old_bus_handler == SIG_IGN) {
+        GC_err_printf0("Previously ignored bus error!?");
+        GC_old_bus_handler = SIG_DFL;
+      }
+      if (GC_old_bus_handler != SIG_DFL) {
+#	ifdef PRINTSTATS
+          GC_err_printf0("Replaced other SIGBUS handler\n");
+#	endif
+      }
+#   endif
+#   if defined(OSF1) || defined(SUNOS4) || defined(LINUX)
+      GC_old_segv_handler = signal(SIGSEGV, (SIG_PF)GC_write_fault_handler);
+      if (GC_old_segv_handler == SIG_IGN) {
+        GC_err_printf0("Previously ignored segmentation violation!?");
+        GC_old_segv_handler = SIG_DFL;
+      }
+      if (GC_old_segv_handler != SIG_DFL) {
+#	ifdef PRINTSTATS
+          GC_err_printf0("Replaced other SIGSEGV handler\n");
+#	endif
+      }
+#   endif
+#   if defined(SUNOS5SIGS) || defined(IRIX5)
+#     if defined(IRIX_THREADS) || defined(IRIX_PCR_THREADS)
+      	sigaction(SIGSEGV, 0, &oldact);
+      	sigaction(SIGSEGV, &act, 0);
+#     else
+      	sigaction(SIGSEGV, &act, &oldact);
+#     endif
+#     if defined(_sigargs)
+	/* This is Irix 5.x, not 6.x.  Irix 5.x does not have	*/
+	/* sa_sigaction.					*/
+	GC_old_segv_handler = oldact.sa_handler;
+#     else /* Irix 6.x or SUNOS5SIGS */
+        if (oldact.sa_flags & SA_SIGINFO) {
+          GC_old_segv_handler = (SIG_PF)(oldact.sa_sigaction);
+        } else {
+          GC_old_segv_handler = oldact.sa_handler;
+        }
+#     endif
+      if (GC_old_segv_handler == SIG_IGN) {
+	     GC_err_printf0("Previously ignored segmentation violation!?");
+	     GC_old_segv_handler = SIG_DFL;
+      }
+      if (GC_old_segv_handler != SIG_DFL) {
+#       ifdef PRINTSTATS
+	  GC_err_printf0("Replaced other SIGSEGV handler\n");
+#       endif
+      }
+#    endif
+#   if defined(MSWIN32)
+      GC_old_segv_handler = SetUnhandledExceptionFilter(GC_write_fault_handler);
+      if (GC_old_segv_handler != NULL) {
+#	ifdef PRINTSTATS
+          GC_err_printf0("Replaced other UnhandledExceptionFilter\n");
+#	endif
+      } else {
+          GC_old_segv_handler = SIG_DFL;
+      }
+#   endif
+}
+
+
+
+void GC_protect_heap()
+{
+    ptr_t start;
+    word len;
+    unsigned i;
+    
+    for (i = 0; i < GC_n_heap_sects; i++) {
+        start = GC_heap_sects[i].hs_start;
+        len = GC_heap_sects[i].hs_bytes;
+        PROTECT(start, len);
+    }
+}
+
+/* We assume that either the world is stopped or its OK to lose dirty	*/
+/* bits while this is happenning (as in GC_enable_incremental).		*/
+void GC_read_dirty()
+{
+    BCOPY((word *)GC_dirty_pages, GC_grungy_pages,
+          (sizeof GC_dirty_pages));
+    BZERO((word *)GC_dirty_pages, (sizeof GC_dirty_pages));
+    GC_protect_heap();
+}
+
+GC_bool GC_page_was_dirty(h)
+struct hblk * h;
+{
+    register word index = PHT_HASH(h);
+    
+    return(HDR(h) == 0 || get_pht_entry_from_index(GC_grungy_pages, index));
+}
+
+/*
+ * Acquiring the allocation lock here is dangerous, since this
+ * can be called from within GC_call_with_alloc_lock, and the cord
+ * package does so.  On systems that allow nested lock acquisition, this
+ * happens to work.
+ * On other systems, SET_LOCK_HOLDER and friends must be suitably defined.
+ */
+ 
+void GC_begin_syscall()
+{
+    if (!I_HOLD_LOCK()) LOCK();
+}
+
+void GC_end_syscall()
+{
+    if (!I_HOLD_LOCK()) UNLOCK();
+}
+
+void GC_unprotect_range(addr, len)
+ptr_t addr;
+word len;
+{
+    struct hblk * start_block;
+    struct hblk * end_block;
+    register struct hblk *h;
+    ptr_t obj_start;
+    
+    if (!GC_incremental) return;
+    obj_start = GC_base(addr);
+    if (obj_start == 0) return;
+    if (GC_base(addr + len - 1) != obj_start) {
+        ABORT("GC_unprotect_range(range bigger than object)");
+    }
+    start_block = (struct hblk *)((word)addr & ~(GC_page_size - 1));
+    end_block = (struct hblk *)((word)(addr + len - 1) & ~(GC_page_size - 1));
+    end_block += GC_page_size/HBLKSIZE - 1;
+    for (h = start_block; h <= end_block; h++) {
+        register word index = PHT_HASH(h);
+        
+        set_pht_entry_from_index(GC_dirty_pages, index);
+    }
+    UNPROTECT(start_block,
+    	      ((ptr_t)end_block - (ptr_t)start_block) + HBLKSIZE);
+}
+
+#ifndef MSWIN32
+/* Replacement for UNIX system call.	 */
+/* Other calls that write to the heap	 */
+/* should be handled similarly.		 */
+# if defined(__STDC__) && !defined(SUNOS4)
+#   include <unistd.h>
+    ssize_t read(int fd, void *buf, size_t nbyte)
+# else
+#   ifndef LINT
+      int read(fd, buf, nbyte)
+#   else
+      int GC_read(fd, buf, nbyte)
+#   endif
+    int fd;
+    char *buf;
+    int nbyte;
+# endif
+{
+    int result;
+    
+    GC_begin_syscall();
+    GC_unprotect_range(buf, (word)nbyte);
+#   ifdef IRIX5
+	/* Indirect system call may not always be easily available.	*/
+	/* We could call _read, but that would interfere with the	*/
+	/* libpthread interception of read.				*/
+	{
+	    struct iovec iov;
+
+	    iov.iov_base = buf;
+	    iov.iov_len = nbyte;
+	    result = readv(fd, &iov, 1);
+	}
+#   else
+    	result = syscall(SYS_read, fd, buf, nbyte);
+#   endif
+    GC_end_syscall();
+    return(result);
+}
+#endif /* !MSWIN32 */
+
+/*ARGSUSED*/
+GC_bool GC_page_was_ever_dirty(h)
+struct hblk *h;
+{
+    return(TRUE);
+}
+
+/* Reset the n pages starting at h to "was never dirty" status.	*/
+/*ARGSUSED*/
+void GC_is_fresh(h, n)
+struct hblk *h;
+word n;
+{
+}
+
+# endif /* MPROTECT_VDB */
+
+# ifdef PROC_VDB
+
+/*
+ * See DEFAULT_VDB for interface descriptions.
+ */
+ 
+/*
+ * This implementaion assumes a Solaris 2.X like /proc pseudo-file-system
+ * from which we can read page modified bits.  This facility is far from
+ * optimal (e.g. we would like to get the info for only some of the
+ * address space), but it avoids intercepting system calls.
+ */
+
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/signal.h>
+#include <sys/fault.h>
+#include <sys/syscall.h>
+#include <sys/procfs.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#define INITIAL_BUF_SZ 4096
+word GC_proc_buf_size = INITIAL_BUF_SZ;
+char *GC_proc_buf;
+
+#ifdef SOLARIS_THREADS
+/* We don't have exact sp values for threads.  So we count on	*/
+/* occasionally declaring stack pages to be fresh.  Thus we 	*/
+/* need a real implementation of GC_is_fresh.  We can't clear	*/
+/* entries in GC_written_pages, since that would declare all	*/
+/* pages with the given hash address to be fresh.		*/
+#   define MAX_FRESH_PAGES 8*1024	/* Must be power of 2 */
+    struct hblk ** GC_fresh_pages;	/* A direct mapped cache.	*/
+    					/* Collisions are dropped.	*/
+
+#   define FRESH_PAGE_SLOT(h) (divHBLKSZ((word)(h)) & (MAX_FRESH_PAGES-1))
+#   define ADD_FRESH_PAGE(h) \
+	GC_fresh_pages[FRESH_PAGE_SLOT(h)] = (h)
+#   define PAGE_IS_FRESH(h) \
+	(GC_fresh_pages[FRESH_PAGE_SLOT(h)] == (h) && (h) != 0)
+#endif
+
+/* Add all pages in pht2 to pht1 */
+void GC_or_pages(pht1, pht2)
+page_hash_table pht1, pht2;
+{
+    register int i;
+    
+    for (i = 0; i < PHT_SIZE; i++) pht1[i] |= pht2[i];
+}
+
+int GC_proc_fd;
+
+void GC_dirty_init()
+{
+    int fd;
+    char buf[30];
+
+    GC_dirty_maintained = TRUE;
+    if (GC_words_allocd != 0 || GC_words_allocd_before_gc != 0) {
+    	register int i;
+    
+        for (i = 0; i < PHT_SIZE; i++) GC_written_pages[i] = (word)(-1);
+#       ifdef PRINTSTATS
+	    GC_printf1("Allocated words:%lu:all pages may have been written\n",
+	    	       (unsigned long)
+	    	      		(GC_words_allocd + GC_words_allocd_before_gc));
+#	endif       
+    }
+    sprintf(buf, "/proc/%d", getpid());
+    fd = open(buf, O_RDONLY);
+    if (fd < 0) {
+    	ABORT("/proc open failed");
+    }
+    GC_proc_fd = syscall(SYS_ioctl, fd, PIOCOPENPD, 0);
+    close(fd);
+    if (GC_proc_fd < 0) {
+    	ABORT("/proc ioctl failed");
+    }
+    GC_proc_buf = GC_scratch_alloc(GC_proc_buf_size);
+#   ifdef SOLARIS_THREADS
+	GC_fresh_pages = (struct hblk **)
+	  GC_scratch_alloc(MAX_FRESH_PAGES * sizeof (struct hblk *));
+	if (GC_fresh_pages == 0) {
+	    GC_err_printf0("No space for fresh pages\n");
+	    EXIT();
+	}
+	BZERO(GC_fresh_pages, MAX_FRESH_PAGES * sizeof (struct hblk *));
+#   endif
+}
+
+/* Ignore write hints. They don't help us here.	*/
+/*ARGSUSED*/
+void GC_write_hint(h)
+struct hblk *h;
+{
+}
+
+#ifdef SOLARIS_THREADS
+#   define READ(fd,buf,nbytes) syscall(SYS_read, fd, buf, nbytes)
+#else
+#   define READ(fd,buf,nbytes) read(fd, buf, nbytes)
+#endif
+
+void GC_read_dirty()
+{
+    unsigned long ps, np;
+    int nmaps;
+    ptr_t vaddr;
+    struct prasmap * map;
+    char * bufp;
+    ptr_t current_addr, limit;
+    int i;
+int dummy;
+
+    BZERO(GC_grungy_pages, (sizeof GC_grungy_pages));
+    
+    bufp = GC_proc_buf;
+    if (READ(GC_proc_fd, bufp, GC_proc_buf_size) <= 0) {
+#	ifdef PRINTSTATS
+            GC_printf1("/proc read failed: GC_proc_buf_size = %lu\n",
+            	       GC_proc_buf_size);
+#	endif       
+        {
+            /* Retry with larger buffer. */
+            word new_size = 2 * GC_proc_buf_size;
+            char * new_buf = GC_scratch_alloc(new_size);
+            
+            if (new_buf != 0) {
+                GC_proc_buf = bufp = new_buf;
+                GC_proc_buf_size = new_size;
+            }
+            if (syscall(SYS_read, GC_proc_fd, bufp, GC_proc_buf_size) <= 0) {
+                WARN("Insufficient space for /proc read\n", 0);
+                /* Punt:	*/
+        	memset(GC_grungy_pages, 0xff, sizeof (page_hash_table));
+		memset(GC_written_pages, 0xff, sizeof(page_hash_table));
+#		ifdef SOLARIS_THREADS
+		    BZERO(GC_fresh_pages,
+		    	  MAX_FRESH_PAGES * sizeof (struct hblk *)); 
+#		endif
+		return;
+            }
+        }
+    }
+    /* Copy dirty bits into GC_grungy_pages */
+    	nmaps = ((struct prpageheader *)bufp) -> pr_nmap;
+	/* printf( "nmaps = %d, PG_REFERENCED = %d, PG_MODIFIED = %d\n",
+		     nmaps, PG_REFERENCED, PG_MODIFIED); */
+	bufp = bufp + sizeof(struct prpageheader);
+	for (i = 0; i < nmaps; i++) {
+	    map = (struct prasmap *)bufp;
+	    vaddr = (ptr_t)(map -> pr_vaddr);
+	    ps = map -> pr_pagesize;
+	    np = map -> pr_npage;
+	    /* printf("vaddr = 0x%X, ps = 0x%X, np = 0x%X\n", vaddr, ps, np); */
+	    limit = vaddr + ps * np;
+	    bufp += sizeof (struct prasmap);
+	    for (current_addr = vaddr;
+	         current_addr < limit; current_addr += ps){
+	        if ((*bufp++) & PG_MODIFIED) {
+	            register struct hblk * h = (struct hblk *) current_addr;
+	            
+	            while ((ptr_t)h < current_addr + ps) {
+	                register word index = PHT_HASH(h);
+	                
+	                set_pht_entry_from_index(GC_grungy_pages, index);
+#			ifdef SOLARIS_THREADS
+			  {
+			    register int slot = FRESH_PAGE_SLOT(h);
+			    
+			    if (GC_fresh_pages[slot] == h) {
+			        GC_fresh_pages[slot] = 0;
+			    }
+			  }
+#			endif
+	                h++;
+	            }
+	        }
+	    }
+	    bufp += sizeof(long) - 1;
+	    bufp = (char *)((unsigned long)bufp & ~(sizeof(long)-1));
+	}
+    /* Update GC_written_pages. */
+        GC_or_pages(GC_written_pages, GC_grungy_pages);
+#   ifdef SOLARIS_THREADS
+      /* Make sure that old stacks are considered completely clean	*/
+      /* unless written again.						*/
+	GC_old_stacks_are_fresh();
+#   endif
+}
+
+#undef READ
+
+GC_bool GC_page_was_dirty(h)
+struct hblk *h;
+{
+    register word index = PHT_HASH(h);
+    register GC_bool result;
+    
+    result = get_pht_entry_from_index(GC_grungy_pages, index);
+#   ifdef SOLARIS_THREADS
+	if (result && PAGE_IS_FRESH(h)) result = FALSE;
+	/* This happens only if page was declared fresh since	*/
+	/* the read_dirty call, e.g. because it's in an unused  */
+	/* thread stack.  It's OK to treat it as clean, in	*/
+	/* that case.  And it's consistent with 		*/
+	/* GC_page_was_ever_dirty.				*/
+#   endif
+    return(result);
+}
+
+GC_bool GC_page_was_ever_dirty(h)
+struct hblk *h;
+{
+    register word index = PHT_HASH(h);
+    register GC_bool result;
+    
+    result = get_pht_entry_from_index(GC_written_pages, index);
+#   ifdef SOLARIS_THREADS
+	if (result && PAGE_IS_FRESH(h)) result = FALSE;
+#   endif
+    return(result);
+}
+
+/* Caller holds allocation lock.	*/
+void GC_is_fresh(h, n)
+struct hblk *h;
+word n;
+{
+
+    register word index;
+    
+#   ifdef SOLARIS_THREADS
+      register word i;
+      
+      if (GC_fresh_pages != 0) {
+        for (i = 0; i < n; i++) {
+          ADD_FRESH_PAGE(h + i);
+        }
+      }
+#   endif
+}
+
+# endif /* PROC_VDB */
+
+
+# ifdef PCR_VDB
+
+# include "vd/PCR_VD.h"
+
+# define NPAGES (32*1024)	/* 128 MB */
+
+PCR_VD_DB  GC_grungy_bits[NPAGES];
+
+ptr_t GC_vd_base;	/* Address corresponding to GC_grungy_bits[0]	*/
+			/* HBLKSIZE aligned.				*/
+
+void GC_dirty_init()
+{
+    GC_dirty_maintained = TRUE;
+    /* For the time being, we assume the heap generally grows up */
+    GC_vd_base = GC_heap_sects[0].hs_start;
+    if (GC_vd_base == 0) {
+   	ABORT("Bad initial heap segment");
+    }
+    if (PCR_VD_Start(HBLKSIZE, GC_vd_base, NPAGES*HBLKSIZE)
+	!= PCR_ERes_okay) {
+	ABORT("dirty bit initialization failed");
+    }
+}
+
+void GC_read_dirty()
+{
+    /* lazily enable dirty bits on newly added heap sects */
+    {
+        static int onhs = 0;
+        int nhs = GC_n_heap_sects;
+        for( ; onhs < nhs; onhs++ ) {
+            PCR_VD_WriteProtectEnable(
+                    GC_heap_sects[onhs].hs_start,
+                    GC_heap_sects[onhs].hs_bytes );
+        }
+    }
+
+
+    if (PCR_VD_Clear(GC_vd_base, NPAGES*HBLKSIZE, GC_grungy_bits)
+        != PCR_ERes_okay) {
+	ABORT("dirty bit read failed");
+    }
+}
+
+GC_bool GC_page_was_dirty(h)
+struct hblk *h;
+{
+    if((ptr_t)h < GC_vd_base || (ptr_t)h >= GC_vd_base + NPAGES*HBLKSIZE) {
+	return(TRUE);
+    }
+    return(GC_grungy_bits[h - (struct hblk *)GC_vd_base] & PCR_VD_DB_dirtyBit);
+}
+
+/*ARGSUSED*/
+void GC_write_hint(h)
+struct hblk *h;
+{
+    PCR_VD_WriteProtectDisable(h, HBLKSIZE);
+    PCR_VD_WriteProtectEnable(h, HBLKSIZE);
+}
+
+# endif /* PCR_VDB */
+
+/*
+ * Call stack save code for debugging.
+ * Should probably be in mach_dep.c, but that requires reorganization.
+ */
+#if defined(SPARC) && !defined(LINUX)
+#   if defined(SUNOS4)
+#     include <machine/frame.h>
+#   else
+#     if defined (DRSNX)
+#	include <sys/sparc/frame.h>
+#     else
+#        if defined(OPENBSD)
+#          include <frame.h>
+#        else
+#          include <sys/frame.h>
+#        endif
+#     endif
+#   endif
+#   if NARGS > 6
+	--> We only know how to to get the first 6 arguments
+#   endif
+
+#ifdef SAVE_CALL_CHAIN
+/* Fill in the pc and argument information for up to NFRAMES of my	*/
+/* callers.  Ignore my frame and my callers frame.			*/
+
+#ifdef OPENBSD
+#  define FR_SAVFP fr_fp
+#  define FR_SAVPC fr_pc
+#else
+#  define FR_SAVFP fr_savfp
+#  define FR_SAVPC fr_savpc
+#endif
+
+void GC_save_callers (info) 
+struct callinfo info[NFRAMES];
+{
+  struct frame *frame;
+  struct frame *fp;
+  int nframes = 0;
+  word GC_save_regs_in_stack();
+
+  frame = (struct frame *) GC_save_regs_in_stack ();
+  
+  for (fp = frame -> FR_SAVFP; fp != 0 && nframes < NFRAMES;
+       fp = fp -> FR_SAVFP, nframes++) {
+      register int i;
+      
+      info[nframes].ci_pc = fp->FR_SAVPC;
+      for (i = 0; i < NARGS; i++) {
+	info[nframes].ci_arg[i] = ~(fp->fr_arg[i]);
+      }
+  }
+  if (nframes < NFRAMES) info[nframes].ci_pc = 0;
+}
+
+#endif /* SAVE_CALL_CHAIN */
+#endif /* SPARC */
+
+
+