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gcconfig.h

/* 
 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
 * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
 * Copyright (c) 1996 by Silicon Graphics.  All rights reserved.
 * Copyright (c) 2000-2004 Hewlett-Packard Development Company, L.P.
 *
 * 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.
 */

/*
 * This header is private to the gc.  It is almost always included from
 * gc_priv.h.  However it is possible to include it by itself if just the
 * configuration macros are needed.  In that
 * case, a few declarations relying on types declared in gc_priv.h will be
 * omitted.
 */
 
#ifndef GCCONFIG_H

# define GCCONFIG_H

# ifndef GC_PRIVATE_H
    /* Fake ptr_t declaration, just to avoid compilation errors.  */
    /* This avoids many instances if "ifndef GC_PRIVATE_H" below. */
    typedef struct GC_undefined_struct * ptr_t;
#   include <stddef.h>  /* For size_t etc. */
# endif

/* Machine dependent parameters.  Some tuning parameters can be found   */
/* near the top of gc_private.h.                            */

/* Machine specific parts contributed by various people.  See README file. */

/* First a unified test for Linux: */
# if defined(linux) || defined(__linux__)
#  ifndef LINUX
#    define LINUX
#  endif
# endif

/* And one for NetBSD: */
# if defined(__NetBSD__)
#    define NETBSD
# endif

/* And one for OpenBSD: */
# if defined(__OpenBSD__)
#    define OPENBSD
# endif

/* And one for FreeBSD: */
# if (defined(__FreeBSD__) || defined(__DragonFly__) || \
      defined(__FreeBSD_kernel__)) && !defined(FREEBSD)
#    define FREEBSD
# endif

/* Determine the machine type: */
# if defined(__arm__) || defined(__thumb__)
#    define ARM32
#    if !defined(LINUX) && !defined(NETBSD)
#      define NOSYS
#      define mach_type_known
#    endif
# endif
# if defined(sun) && defined(mc68000)
#    error SUNOS4 no longer supported
# endif
# if defined(hp9000s300)
#    error M68K based HP machines no longer supported.
# endif
# if defined(OPENBSD) && defined(m68k)
#    define M68K
#    define mach_type_known
# endif
# if defined(OPENBSD) && defined(__sparc__)
#    define SPARC
#    define mach_type_known
# endif
# if defined(NETBSD) && (defined(m68k) || defined(__m68k__))
#    define M68K
#    define mach_type_known
# endif
# if defined(NETBSD) && defined(__powerpc__)
#    define POWERPC
#    define mach_type_known
# endif
# if defined(NETBSD) && (defined(__arm32__) || defined(__arm__))
#    define ARM32
#    define mach_type_known
# endif
# if defined(NETBSD) && defined(__sh__)
#    define SH
#    define mach_type_known
# endif
# if defined(vax)
#    define VAX
#    ifdef ultrix
#     define ULTRIX
#    else
#     define BSD
#    endif
#    define mach_type_known
# endif
# if defined(__NetBSD__) && defined(__vax__)
#    define VAX
#    define mach_type_known
# endif
# if defined(mips) || defined(__mips) || defined(_mips)
#    define MIPS
#    if defined(nec_ews) || defined(_nec_ews)
#      define EWS4800
#    endif
#    if !defined(LINUX) && !defined(EWS4800) && !defined(NETBSD)
#      if defined(ultrix) || defined(__ultrix)
#      define ULTRIX
#      else
#      define IRIX5   /* or IRIX 6.X */
#      endif
#    endif /* !LINUX */
#    if defined(__NetBSD__) && defined(__MIPSEL__)
#      undef ULTRIX
#    endif
#    define mach_type_known
# endif
# if defined(DGUX) && (defined(i386) || defined(__i386__))
#    define I386
#    ifndef _USING_DGUX
#    define _USING_DGUX
#    endif
#    define mach_type_known
# endif
# if defined(sequent) && (defined(i386) || defined(__i386__))
#    define I386
#    define SEQUENT
#    define mach_type_known
# endif
# if (defined(sun) || defined(__sun)) && (defined(i386) || defined(__i386__))
#    define I386
#    define SOLARIS
#    define mach_type_known
# endif
# if (defined(sun) || defined(__sun)) && defined(__amd64)
#    define X86_64
#    define SOLARIS
#    define mach_type_known
# endif
# if (defined(__OS2__) || defined(__EMX__)) && defined(__32BIT__)
#    define I386
#    define OS2
#    define mach_type_known
# endif
# if defined(ibm032)
#   error IBM PC/RT no longer supported.
# endif
# if defined(sun) && (defined(sparc) || defined(__sparc))
#   define SPARC
    /* Test for SunOS 5.x */
#     include <errno.h>
#     define SOLARIS
#   define mach_type_known
# endif
# if defined(sparc) && defined(unix) && !defined(sun) && !defined(linux) \
     && !defined(__OpenBSD__) && !defined(__NetBSD__) && !defined(__FreeBSD__) \
     && !defined(__DragonFly__)
#   define SPARC
#   define DRSNX
#   define mach_type_known
# endif
# if defined(_IBMR2)
#   define POWERPC
#   define AIX
#   define mach_type_known
# endif
# if defined(__NetBSD__) && defined(__sparc__)
#   define SPARC
#   define mach_type_known
# endif
# if defined(_M_XENIX) && defined(_M_SYSV) && defined(_M_I386)
      /* The above test may need refinement     */
#   define I386
#   if defined(_SCO_ELF)
#     define SCO_ELF
#   else
#     define SCO
#   endif
#   define mach_type_known
# endif
# if defined(_AUX_SOURCE)
#   error A/UX no longer supported
# endif
# if defined(_PA_RISC1_0) || defined(_PA_RISC1_1) || defined(_PA_RISC2_0) \
     || defined(hppa) || defined(__hppa__)
#   define HP_PA
#   if !defined(LINUX) && !defined(HPUX)
#     define HPUX
#   endif
#   define mach_type_known
# endif
# if defined(__ia64) && (defined(_HPUX_SOURCE) || defined(__HP_aCC))
#   define IA64
#   ifndef HPUX
#     define HPUX
#   endif
#   define mach_type_known
# endif
# if defined(__BEOS__) && defined(_X86_)
#    define I386
#    define BEOS
#    define mach_type_known
# endif
# if defined(LINUX) && (defined(i386) || defined(__i386__))
#    define I386
#    define mach_type_known
# endif
# if defined(LINUX) && defined(__x86_64__)
#    define X86_64
#    define mach_type_known
# endif
# if defined(LINUX) && (defined(__ia64__) || defined(__ia64))
#    define IA64
#    define mach_type_known
# endif
# if defined(LINUX) && defined(__arm__)
#    define ARM32
#    define mach_type_known
# endif
# if defined(LINUX) && defined(__cris__)
#    ifndef CRIS
#     define CRIS
#    endif
#    define mach_type_known
# endif
# if defined(LINUX) && (defined(powerpc) || defined(__powerpc__) || \
                    defined(powerpc64) || defined(__powerpc64__))
#    define POWERPC
#    define mach_type_known
# endif
# if defined(FREEBSD) && (defined(powerpc) || defined(__powerpc__))
#    define POWERPC
#    define mach_type_known
# endif
# if defined(LINUX) && defined(__mc68000__)
#    define M68K
#    define mach_type_known
# endif
# if defined(LINUX) && (defined(sparc) || defined(__sparc__))
#    define SPARC
#    define mach_type_known
# endif
# if defined(LINUX) && defined(__arm__)
#    define ARM32
#    define mach_type_known
# endif
# if defined(LINUX) && defined(__sh__)
#    define SH
#    define mach_type_known
# endif
# if defined(LINUX) && defined(__m32r__)
#    define M32R
#    define mach_type_known
# endif
# if defined(__alpha) || defined(__alpha__)
#   define ALPHA
#   if !defined(LINUX) && !defined(NETBSD) && !defined(OPENBSD) && !defined(FREEBSD)
#     define OSF1 /* a.k.a Digital Unix */
#   endif
#   define mach_type_known
# endif
# if defined(_AMIGA) && !defined(AMIGA)
#   define AMIGA
# endif
# ifdef AMIGA 
#   define M68K
#   define mach_type_known
# endif
# if defined(THINK_C) || defined(__MWERKS__) && !defined(__powerc)
#   define M68K
#   define MACOS
#   define mach_type_known
# endif
# if defined(__MWERKS__) && defined(__powerc) && !defined(__MACH__)
#   define POWERPC
#   define MACOS
#   define mach_type_known
# endif
# if defined(macosx) || (defined(__APPLE__) && defined(__MACH__))
#   define DARWIN
#   if defined(__ppc__)  || defined(__ppc64__)
#    define POWERPC
#    define mach_type_known
#   elif defined(__x86_64__)
#    define X86_64
#    define mach_type_known
#   elif defined(__i386__)
#    define I386
#    define mach_type_known
#   endif
# endif
# if defined(NeXT) && defined(mc68000)
#   define M68K
#   define NEXT
#   define mach_type_known
# endif
# if defined(NeXT) && (defined(i386) || defined(__i386__))
#   define I386
#   define NEXT
#   define mach_type_known
# endif
# if defined(__OpenBSD__) && (defined(i386) || defined(__i386__))
#   define I386
#   define OPENBSD
#   define mach_type_known
# endif
# if defined(FREEBSD) && (defined(i386) || defined(__i386__))
#   define I386
#   define mach_type_known
# endif
# if defined(FREEBSD) && defined(__x86_64__)
#   define X86_64
#   define mach_type_known
# endif
# if defined(__NetBSD__) && (defined(i386) || defined(__i386__))
#   define I386
#   define mach_type_known
# endif
# if defined(__NetBSD__) && defined(__x86_64__)
#    define X86_64
#    define mach_type_known
# endif
# if defined(FREEBSD) && defined(__sparc__)
#    define SPARC
#    define mach_type_known
# endif
# if defined(bsdi) && (defined(i386) || defined(__i386__))
#    define I386
#    define BSDI
#    define mach_type_known
# endif
# if !defined(mach_type_known) && defined(__386BSD__)
#   define I386
#   define THREE86BSD
#   define mach_type_known
# endif
# if defined(_CX_UX) && defined(_M88K)
#   define M88K
#   define CX_UX
#   define mach_type_known
# endif
# if defined(DGUX) && defined(m88k)
#   define M88K
    /* DGUX defined */
#   define mach_type_known
# endif
# if defined(_WIN32_WCE)
    /* SH3, SH4, MIPS already defined for corresponding architectures */
#   if defined(SH3) || defined(SH4)
#     define SH
#   endif
#   if defined(x86)
#     define I386
#   endif
#   if defined(ARM)
#     define ARM32
#   endif
#   define MSWINCE
#   define mach_type_known
# else
#   if (defined(_MSDOS) || defined(_MSC_VER)) && (_M_IX86 >= 300) \
        || defined(_WIN32) && !defined(__CYGWIN32__) && !defined(__CYGWIN__)
#     if defined(__LP64__) || defined(_WIN64)
#     define X86_64
#     else
#       define I386
#     endif
#     define MSWIN32    /* or Win64 */
#     define mach_type_known
#   endif
#   if defined(_MSC_VER) && defined(_M_IA64)
#     define IA64
#     define MSWIN32    /* Really win64, but we don't treat 64-bit      */
                  /* variants as a differnt platform.       */
#   endif
# endif
# if defined(__DJGPP__)
#   define I386
#   ifndef DJGPP
#     define DJGPP  /* MSDOS running the DJGPP port of GCC */
#   endif
#   define mach_type_known
# endif
# if defined(__CYGWIN32__) || defined(__CYGWIN__)
#   define I386
#   define CYGWIN32
#   define mach_type_known
# endif
# if defined(__MINGW32__)
#   define I386
#   define MSWIN32
#   define mach_type_known
# endif
# if defined(__BORLANDC__)
#   define I386
#   define MSWIN32
#   define mach_type_known
# endif
# if defined(_UTS) && !defined(mach_type_known)
#   define S370
#   define UTS4
#   define mach_type_known
# endif
# if defined(__pj__)
#   error PicoJava no longer supported
    /* The implementation had problems, and I haven't heard of users    */
    /* in ages.  If you want it resurrected, let me know.         */
# endif
# if defined(__embedded__) && defined(PPC)
#   define POWERPC
#   define NOSYS
#   define mach_type_known
# endif
/* Ivan Demakov */
# if defined(__WATCOMC__) && defined(__386__)
#   define I386
#   if !defined(OS2) && !defined(MSWIN32) && !defined(DOS4GW)
#     if defined(__OS2__)
#       define OS2
#     else
#       if defined(__WINDOWS_386__) || defined(__NT__)
#         define MSWIN32
#       else
#         define DOS4GW
#       endif
#     endif
#   endif
#   define mach_type_known
# endif
# if defined(__s390__) && defined(LINUX)
#    define S390
#    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
# if defined(__TANDEM)
    /* Nonstop S-series */
    /* FIXME: Should recognize Integrity series? */
#   define MIPS
#   define NONSTOP
#   define mach_type_known
# endif

/* Feel free to add more clauses here */

/* Or manually define the machine type here.  A machine type is   */
/* characterized by the architecture.  Some                       */
/* machine types are further subdivided by OS.                    */
/* Macros such as LINUX, FREEBSD, etc. distinguish them.          */
/* SYSV on an M68K actually means A/UX.                           */
/* The distinction in these cases is usually the stack starting address */
# ifndef mach_type_known
#   error "The collector has not been ported to this machine/OS combination."
# endif
                /* Mapping is: M68K       ==> Motorola 680X0      */
                /*               (NEXT, and SYSV (A/UX),          */
                /*               MACOS and AMIGA variants)        */
                /*             I386       ==> Intel 386           */
                /*                (SEQUENT, OS2, SCO, LINUX, NETBSD,    */
                /*                 FREEBSD, THREE86BSD, MSWIN32,  */
                /*                 BSDI,SOLARIS, NEXT, other variants)  */
                    /*             NS32K      ==> Encore Multimax       */
                    /*             MIPS       ==> R2000 through R14K    */
                    /*              (many variants)               */
                    /*           VAX            ==> DEC VAX       */
                    /*              (BSD, ULTRIX variants)        */
                    /*           HP_PA      ==> HP9000/700 & /800 */
                    /*                      HP/UX, LINUX          */
                /*               SPARC      ==> SPARC v7/v8/v9    */
                /*                  (SOLARIS, LINUX, DRSNX variants)    */
                /*               ALPHA      ==> DEC Alpha         */
                /*                  (OSF1 and LINUX variants)     */
                /*               M88K       ==> Motorola 88XX0        */
                /*                    (CX_UX and DGUX)            */
                /*               S370           ==> 370-like machine    */
                /*                  running Amdahl UTS4           */
                    /*             S390       ==> 390-like machine      */
                /*                  running LINUX                   */
                /*               ARM32      ==> Intel StrongARM   */
                /*               IA64           ==> Intel IPF           */
                /*                          (e.g. Itanium)  */
                /*                  (LINUX and HPUX)          */
                /*               SH       ==> Hitachi SuperH      */
                /*                  (LINUX & MSWINCE)       */
                /*               X86_64     ==> AMD x86-64        */
                /*               POWERPC    ==> IBM/Apple PowerPC */
                /*                  (MACOS(<=9),DARWIN(incl.MACOSX),*/
                /*                   LINUX, NETBSD, AIX, NOSYS    */
                /*                   variants)              */
                /*                  Handles 32 and 64-bit variants.     */
                /*               CRIS       ==> Axis Etrax        */
                /*               M32R           ==> Renesas M32R        */


/*
 * For each architecture and OS, the following need to be defined:
 *
 * CPP_WORDSZ is a simple integer constant representing the word size.
 * in bits.  We assume byte addressibility, where a byte has 8 bits.
 * We also assume CPP_WORDSZ is either 32 or 64.
 * (We care about the length of pointers, not hardware
 * bus widths.  Thus a 64 bit processor with a C compiler that uses
 * 32 bit pointers should use CPP_WORDSZ of 32, not 64. Default is 32.)
 *
 * MACH_TYPE is a string representation of the machine type.
 * OS_TYPE is analogous for the OS.
 *
 * ALIGNMENT is the largest N, such that
 * all pointer are guaranteed to be aligned on N byte boundaries.
 * defining it to be 1 will always work, but perform poorly.
 *
 * DATASTART is the beginning of the data segment.
 * On some platforms SEARCH_FOR_DATA_START is defined.
 * SEARCH_FOR_DATASTART will cause GC_data_start to
 * be set to an address determined by accessing data backwards from _end
 * until an unmapped page is found.  DATASTART will be defined to be
 * GC_data_start.
 * On UNIX-like systems, the collector will scan the area between DATASTART
 * and DATAEND for root pointers.
 *
 * DATAEND, if not `end' where `end' is defined as ``extern int end[];''.
 * RTH suggests gaining access to linker script synth'd values with
 * this idiom instead of `&end' where `end' is defined as ``extern int end;'' .
 * Otherwise, ``GCC will assume these are in .sdata/.sbss'' and it will, e.g.,
 * cause failures on alpha*-*-* with ``-msmall-data or -fpic'' or mips-*-*
 * without any special options.
 *
 * STACKBOTTOM is the cool end of the stack, which is usually the
 * highest address in the stack.
 * Under PCR or OS/2, we have other ways of finding thread stacks.
 * For each machine, the following should:
 * 1) define STACK_GROWS_UP if the stack grows toward higher addresses, and
 * 2) define exactly one of
 *    STACKBOTTOM (should be defined to be an expression)
 *    LINUX_STACKBOTTOM
 *    HEURISTIC1
 *    HEURISTIC2
 * If STACKBOTTOM is defined, then it's value will be used directly as the
 * stack base.  If LINUX_STACKBOTTOM is defined, then it will be determined
 * with a method appropriate for most Linux systems.  Currently we look
 * first for __libc_stack_end (currently only id USE_LIBC_PRIVATES is
 * defined), and if that fails read it from /proc.  (If USE_LIBC_PRIVATES
 * is not defined and NO_PROC_STAT is defined, we revert to HEURISTIC2.)
 * If either of the last two macros are defined, then STACKBOTTOM is computed
 * during collector startup using one of the following two heuristics:
 * HEURISTIC1:  Take an address inside GC_init's frame, and round it up to
 *          the next multiple of STACK_GRAN.
 * HEURISTIC2:  Take an address inside GC_init's frame, increment it repeatedly
 *          in small steps (decrement if STACK_GROWS_UP), and read the value
 *          at each location.  Remember the value when the first
 *          Segmentation violation or Bus error is signalled.  Round that
 *          to the nearest plausible page boundary, and use that instead
 *          of STACKBOTTOM.
 *
 * Gustavo Rodriguez-Rivera points out that on most (all?) Unix machines,
 * the value of environ is a pointer that can serve as STACKBOTTOM.
 * I expect that HEURISTIC2 can be replaced by this approach, which
 * interferes far less with debugging.  However it has the disadvantage
 * that it's confused by a putenv call before the collector is initialized.
 * This could be dealt with by intercepting putenv ...
 *
 * If no expression for STACKBOTTOM can be found, and neither of the above
 * heuristics are usable, the collector can still be used with all of the above
 * undefined, provided one of the following is done:
 * 1) GC_mark_roots can be changed to somehow mark from the correct stack(s)
 *    without reference to STACKBOTTOM.  This is appropriate for use in
 *    conjunction with thread packages, since there will be multiple stacks.
 *    (Allocating thread stacks in the heap, and treating them as ordinary
 *    heap data objects is also possible as a last resort.  However, this is
 *    likely to introduce significant amounts of excess storage retention
 *    unless the dead parts of the thread stacks are periodically cleared.)
 * 2) Client code may set GC_stackbottom before calling any GC_ routines.
 *    If the author of the client code controls the main program, this is
 *    easily accomplished by introducing a new main program, setting
 *    GC_stackbottom to the address of a local variable, and then calling
 *    the original main program.  The new main program would read something
 *    like:
 *
 *          # include "gc_private.h"
 *
 *          main(argc, argv, envp)
 *          int argc;
 *          char **argv, **envp;
 *          {
 *              int dummy;
 *
 *              GC_stackbottom = (ptr_t)(&dummy);
 *              return(real_main(argc, argv, envp));
 *          }
 *
 *
 * Each architecture may also define the style of virtual dirty bit
 * implementation to be used:
 *   MPROTECT_VDB: Write protect the heap and catch faults.
 *   GWW_VDB: Use win32 GetWriteWatch primitive.
 *   PROC_VDB: Use the SVR4 /proc primitives to read dirty bits.
 *
 * The first and second one may be combined, in which case a runtime
 * selection will be made, based on GetWriteWatch availability.
 *
 * An architecture may define DYNAMIC_LOADING if dynamic_load.c
 * defined GC_register_dynamic_libraries() for the architecture.
 *
 * An architecture may define PREFETCH(x) to preload the cache with *x.
 * This defaults to a no-op.
 *
 * PREFETCH_FOR_WRITE(x) is used if *x is about to be written.
 *
 * An architecture may also define CLEAR_DOUBLE(x) to be a fast way to
 * clear the two words at GC_malloc-aligned address x.  By default,
 * word stores of 0 are used instead.
 *
 * HEAP_START may be defined as the initial address hint for mmap-based
 * allocation.
 */

/* If we are using a recent version of gcc, we can use __builtin_unwind_init()
 * to push the relevant registers onto the stack.
 */
# if defined(__GNUC__) && ((__GNUC__ >= 3) || \
                     (__GNUC__ == 2 && __GNUC_MINOR__ >= 8)) \
                   && !defined(__INTEL_COMPILER) && !defined(__PATHCC__)
#   define HAVE_BUILTIN_UNWIND_INIT
# endif

# define STACK_GRAN 0x1000000
# ifdef M68K
#   define MACH_TYPE "M68K"
#   define ALIGNMENT 2
#   ifdef OPENBSD
#     define OS_TYPE "OPENBSD"
#     define HEURISTIC2
#     ifdef __ELF__
#       define DATASTART GC_data_start
#       define DYNAMIC_LOADING
#     else
        extern char etext[];
#       define DATASTART ((ptr_t)(etext))
#       endif
#   endif
#   ifdef NETBSD
#     define OS_TYPE "NETBSD"
#     define HEURISTIC2
#     ifdef __ELF__
#       define DATASTART GC_data_start
#       define DYNAMIC_LOADING
#     else
        extern char etext[];
#       define DATASTART ((ptr_t)(etext))
#       endif
#   endif
#   ifdef LINUX
#       define OS_TYPE "LINUX"
#       define LINUX_STACKBOTTOM
#       define MPROTECT_VDB
#       ifdef __ELF__
#            define DYNAMIC_LOADING
#          include <features.h>
#          if defined(__GLIBC__)&& __GLIBC__>=2
#              define SEARCH_FOR_DATA_START
#          else /* !GLIBC2 */
               extern char **__environ;
#              define DATASTART ((ptr_t)(&__environ))
                             /* hideous kludge: __environ is the first */
                             /* word in crt0.o, and delimits the start */
                             /* of the data segment, no matter which   */
                             /* ld options were passed through.        */
                             /* We could use _etext instead, but that  */
                             /* would include .rodata, which may       */
                             /* contain large read-only data tables    */
                             /* that we'd rather not scan.             */
#          endif /* !GLIBC2 */
             extern int _end[];
#            define DATAEND (_end)
#       else
             extern int etext[];
#            define DATASTART ((ptr_t)((((word) (etext)) + 0xfff) & ~0xfff))
#       endif
#   endif
#   ifdef AMIGA
#     define OS_TYPE "AMIGA"
            /* STACKBOTTOM and DATASTART handled specially  */
            /* in os_dep.c                            */
#     define DATAEND    /* not needed */
#     define GETPAGESIZE() 4096
#   endif
#   ifdef MACOS
#     ifndef __LOWMEM__
#     include <LowMem.h>
#     endif
#     define OS_TYPE "MACOS"
                  /* see os_dep.c for details of global data segments. */
#     define STACKBOTTOM ((ptr_t) LMGetCurStackBase())
#     define DATAEND    /* not needed */
#     define GETPAGESIZE() 4096
#   endif
#   ifdef NEXT
#     define OS_TYPE "NEXT"
#     define DATASTART ((ptr_t) get_etext())
#     define STACKBOTTOM ((ptr_t) 0x4000000)
#     define DATAEND    /* not needed */
#   endif
# endif

# if defined(POWERPC)
#   define MACH_TYPE "POWERPC"
#   ifdef MACOS
#     define ALIGNMENT 2  /* Still necessary?  Could it be 4?     */
#     ifndef __LOWMEM__
#     include <LowMem.h>
#     endif
#     define OS_TYPE "MACOS"
                  /* see os_dep.c for details of global data segments. */
#     define STACKBOTTOM ((ptr_t) LMGetCurStackBase())
#     define DATAEND  /* not needed */
#   endif
#   ifdef LINUX
#     if defined(__powerpc64__)
#       define ALIGNMENT 8
#       define CPP_WORDSZ 64
#       ifndef HBLKSIZE
#         define HBLKSIZE 4096
#       endif
#     else
#       define ALIGNMENT 4
#     endif
#     define OS_TYPE "LINUX"
      /* HEURISTIC1 has been reliably reported to fail for a 32-bit     */
      /* executable on a 64 bit kernel.                           */
#     define LINUX_STACKBOTTOM
#     define DYNAMIC_LOADING
#     define SEARCH_FOR_DATA_START
      extern int _end[];
#     define DATAEND (_end)
#   endif
#   ifdef DARWIN
#     define OS_TYPE "DARWIN"
#     define DYNAMIC_LOADING
#     if defined(__ppc64__)
#       define ALIGNMENT 8
#       define CPP_WORDSZ 64
#       define STACKBOTTOM ((ptr_t) 0x7fff5fc00000)
#       define CACHE_LINE_SIZE 64
#       ifndef HBLKSIZE
#         define HBLKSIZE 4096
#       endif
#     else
#       define ALIGNMENT 4
#       define STACKBOTTOM ((ptr_t) 0xc0000000)
#     endif
      /* XXX: see get_end(3), get_etext() and get_end() should not be used.
       These aren't used when dyld support is enabled (it is by default) */
#     define DATASTART ((ptr_t) get_etext())
#     define DATAEND    ((ptr_t) get_end())
#     define USE_MMAP
#     define USE_MMAP_ANON
#     ifdef GC_DARWIN_THREADS
#       define MPROTECT_VDB
#     endif
#     include <unistd.h>
#     define GETPAGESIZE() getpagesize()
#     if defined(USE_PPC_PREFETCH) && defined(__GNUC__)
      /* The performance impact of prefetches is untested */
#     define PREFETCH(x) \
        __asm__ __volatile__ ("dcbt 0,%0" : : "r" ((const void *) (x)))
#     define PREFETCH_FOR_WRITE(x) \
        __asm__ __volatile__ ("dcbtst 0,%0" : : "r" ((const void *) (x)))
#     endif
      /* There seems to be some issues with trylock hanging on darwin. This
       should be looked into some more */
#     define NO_PTHREAD_TRYLOCK
#   endif
#   ifdef FREEBSD
#       define ALIGNMENT 4
#       define OS_TYPE "FREEBSD"
#       ifndef GC_FREEBSD_THREADS
#           define MPROTECT_VDB
#       endif
#       define SIG_SUSPEND SIGUSR1
#       define SIG_THR_RESTART SIGUSR2
#       define FREEBSD_STACKBOTTOM
#       ifdef __ELF__
#           define DYNAMIC_LOADING
#       endif
        extern char etext[];
        extern char * GC_FreeBSDGetDataStart();
#       define DATASTART GC_FreeBSDGetDataStart(0x1000, &etext)
#   endif
#   ifdef NETBSD
#     define ALIGNMENT 4
#     define OS_TYPE "NETBSD"
#     define HEURISTIC2
      extern char etext[];
#     define DATASTART GC_data_start
#     define DYNAMIC_LOADING
#   endif
#   ifdef AIX
#     define OS_TYPE "AIX"
#     undef ALIGNMENT /* in case it's defined   */
#     ifdef IA64
#       undef IA64
          /* DOB: some AIX installs stupidly define IA64 in */
          /* /usr/include/sys/systemcfg.h                 */
#     endif
#     ifdef __64BIT__
#       define ALIGNMENT 8
#       define CPP_WORDSZ 64
#       define STACKBOTTOM ((ptr_t)0x1000000000000000)
#     else
#       define ALIGNMENT 4
#       define CPP_WORDSZ 32
#       define STACKBOTTOM ((ptr_t)((ulong)&errno))
#     endif
#     define USE_MMAP
#     define USE_MMAP_ANON
      /* From AIX linker man page:
      _text Specifies the first location of the program.
      _etext Specifies the first location after the program.
      _data Specifies the first location of the data.
      _edata Specifies the first location after the initialized data
      _end or end Specifies the first location after all data.
      */
      extern int _data[], _end[];
#     define DATASTART ((ptr_t)((ulong)_data))
#     define DATAEND ((ptr_t)((ulong)_end))
      extern int errno;
#     define DYNAMIC_LOADING
      /* For really old versions of AIX, this may have to be removed. */
#   endif

#   ifdef NOSYS
#     define ALIGNMENT 4
#     define OS_TYPE "NOSYS"
      extern void __end[], __dso_handle[];
#     define DATASTART (__dso_handle)  /* OK, that's ugly.  */
#     define DATAEND (__end)
      /* Stack starts at 0xE0000000 for the simulator.  */
#     undef STACK_GRAN
#     define STACK_GRAN 0x10000000
#     define HEURISTIC1
#   endif
# endif

# ifdef VAX
#   define MACH_TYPE "VAX"
#   define ALIGNMENT 4  /* Pointers are longword aligned by 4.2 C compiler */
    extern char etext[];
#   define DATASTART ((ptr_t)(etext))
#   ifdef BSD
#     define OS_TYPE "BSD"
#     define HEURISTIC1
                  /* HEURISTIC2 may be OK, but it's hard to test. */
#   endif
#   ifdef ULTRIX
#     define OS_TYPE "ULTRIX"
#     define STACKBOTTOM ((ptr_t) 0x7fffc800)
#   endif
# endif

# ifdef SPARC
#   define MACH_TYPE "SPARC"
#   if defined(__arch64__) || defined(__sparcv9)
#     define ALIGNMENT 8
#     define CPP_WORDSZ 64
#     define ELF_CLASS ELFCLASS64
#   else
#     define ALIGNMENT 4      /* Required by hardware */
#     define CPP_WORDSZ 32
#   endif
    /* Don't define USE_ASM_PUSH_REGS.  We do use an asm helper, but    */
    /* not to push the registers on the mark stack.               */
#   ifdef SOLARIS
#     define OS_TYPE "SOLARIS"
      extern int _etext[];
      extern int _end[];
      extern ptr_t GC_SysVGetDataStart(size_t, ptr_t);
#       define DATASTART GC_SysVGetDataStart(0x10000, (ptr_t)_etext)
#     define DATAEND (_end)
#     if !defined(USE_MMAP) && defined(REDIRECT_MALLOC)
#         define USE_MMAP
          /* Otherwise we now use calloc.  Mmap may result in the */
          /* heap interleaved with thread stacks, which can result in   */
          /* excessive blacklisting.  Sbrk is unusable since it   */
          /* doesn't interact correctly with the system malloc.   */
#     endif
#       ifdef USE_MMAP
#         define HEAP_START (ptr_t)0x40000000
#       else
#       define HEAP_START DATAEND
#       endif
#     define PROC_VDB
/*    HEURISTIC1 reportedly no longer works under 2.7.            */
/*    HEURISTIC2 probably works, but this appears to be preferable.     */
/*    Apparently USRSTACK is defined to be USERLIMIT, but in some */
/*    installations that's undefined.  We work around this with a */
/*    gross hack:                                     */
#       include <sys/vmparam.h>
#     ifdef USERLIMIT
        /* This should work everywhere, but doesn't.  */
#       define STACKBOTTOM USRSTACK
#       else
#       define HEURISTIC2
#       endif
#     include <unistd.h>
#       define GETPAGESIZE()  sysconf(_SC_PAGESIZE)
            /* getpagesize() appeared to be missing from at least one */
            /* Solaris 5.4 installation.  Weird.                    */
#     define DYNAMIC_LOADING
#   endif
#   ifdef DRSNX
#     define OS_TYPE "DRSNX"
      extern ptr_t GC_SysVGetDataStart(size_t, ptr_t);
      extern int etext[];
#       define DATASTART GC_SysVGetDataStart(0x10000, (ptr_t)etext)
#     define MPROTECT_VDB
#       define STACKBOTTOM ((ptr_t) 0xdfff0000)
#     define DYNAMIC_LOADING
#   endif
#   ifdef LINUX
#     define OS_TYPE "LINUX"
#     ifdef __ELF__
#       define DYNAMIC_LOADING
#     else
          Linux Sparc/a.out not supported
#     endif
      extern int _end[];
      extern int _etext[];
#     define DATAEND (_end)
#     define SVR4
      extern ptr_t GC_SysVGetDataStart(size_t, ptr_t);
#     ifdef __arch64__
#     define DATASTART GC_SysVGetDataStart(0x100000, (ptr_t)_etext)
#     else
#       define DATASTART GC_SysVGetDataStart(0x10000, (ptr_t)_etext)
#     endif
#     define LINUX_STACKBOTTOM
#   endif
#   ifdef OPENBSD
#     define OS_TYPE "OPENBSD"
#     define STACKBOTTOM ((ptr_t) 0xf8000000)
      extern int etext[];
#     define DATASTART ((ptr_t)(etext))
#   endif
#   ifdef NETBSD
#     define OS_TYPE "NETBSD"
#     define HEURISTIC2
#     ifdef __ELF__
#     define DATASTART GC_data_start
#     define DYNAMIC_LOADING
#     else
      extern char etext[];
#     define DATASTART ((ptr_t)(etext))
#     endif
#   endif
#   ifdef FREEBSD
#     define OS_TYPE "FREEBSD"
#     define SIG_SUSPEND SIGUSR1
#     define SIG_THR_RESTART SIGUSR2
#     define FREEBSD_STACKBOTTOM
#     ifdef __ELF__
#         define DYNAMIC_LOADING
#     endif
      extern char etext[];
      extern char edata[];
      extern char end[];
#     define NEED_FIND_LIMIT
#     define DATASTART ((ptr_t)(&etext))
#     define DATAEND (GC_find_limit (DATASTART, TRUE))
#     define DATASTART2 ((ptr_t)(&edata))
#     define DATAEND2 ((ptr_t)(&end))
#   endif
# endif

# ifdef I386
#   define MACH_TYPE "I386"
#   if defined(__LP64__) || defined(_WIN64)
#     error This should be handled as X86_64
#   else
#     define CPP_WORDSZ 32
#     define ALIGNMENT 4
                  /* Appears to hold for all "32 bit" compilers   */
                  /* except Borland.  The -a4 option fixes  */
                  /* Borland.                         */
                        /* Ivan Demakov: For Watcom the option is -zp4. */
#   endif
#   ifdef SEQUENT
#     define OS_TYPE "SEQUENT"
      extern int etext[];
#       define DATASTART ((ptr_t)((((word) (etext)) + 0xfff) & ~0xfff))
#       define STACKBOTTOM ((ptr_t) 0x3ffff000) 
#   endif
#   ifdef BEOS
#     define OS_TYPE "BEOS"
#     include <OS.h>
#     define GETPAGESIZE() B_PAGE_SIZE
      extern int etext[];
#     define DATASTART ((ptr_t)((((word) (etext)) + 0xfff) & ~0xfff))
#   endif
#   ifdef SOLARIS
#     define OS_TYPE "SOLARIS"
        extern int _etext[], _end[];
      extern ptr_t GC_SysVGetDataStart(size_t, ptr_t);
#       define DATASTART GC_SysVGetDataStart(0x1000, (ptr_t)_etext)
#     define DATAEND (_end)
/*    # define STACKBOTTOM ((ptr_t)(_start)) worked through 2.7,        */
/*      but reportedly breaks under 2.8.  It appears that the stack     */
/*    base is a property of the executable, so this should not break    */
/*    old executables.                                */
/*    HEURISTIC2 probably works, but this appears to be preferable.     */
#       include <sys/vm.h>
#     define STACKBOTTOM USRSTACK
/* At least in Solaris 2.5, PROC_VDB gives wrong values for dirty bits. */
/* It appears to be fixed in 2.8 and 2.9.                   */
#     ifdef SOLARIS25_PROC_VDB_BUG_FIXED
#       define PROC_VDB
#     endif
#     define DYNAMIC_LOADING
#     if !defined(USE_MMAP) && defined(REDIRECT_MALLOC)
#         define USE_MMAP
          /* Otherwise we now use calloc.  Mmap may result in the */
          /* heap interleaved with thread stacks, which can result in   */
          /* excessive blacklisting.  Sbrk is unusable since it   */
          /* doesn't interact correctly with the system malloc.   */
#     endif
#       ifdef USE_MMAP
#         define HEAP_START (ptr_t)0x40000000
#       else
#       define HEAP_START DATAEND
#       endif
#   endif
#   ifdef SCO
#     define OS_TYPE "SCO"
      extern int etext[];
#     define DATASTART ((ptr_t)((((word) (etext)) + 0x3fffff) \
                          & ~0x3fffff) \
                         +((word)etext & 0xfff))
#     define STACKBOTTOM ((ptr_t) 0x7ffffffc)
#   endif
#   ifdef SCO_ELF
#       define OS_TYPE "SCO_ELF"
        extern int etext[];
#       define DATASTART ((ptr_t)(etext))
#       define STACKBOTTOM ((ptr_t) 0x08048000)
#       define DYNAMIC_LOADING
#     define ELF_CLASS ELFCLASS32
#   endif
#   ifdef DGUX
#     define OS_TYPE "DGUX"
      extern int _etext, _end;
      extern ptr_t GC_SysVGetDataStart(size_t, ptr_t);
#     define DATASTART GC_SysVGetDataStart(0x1000, (ptr_t)(&_etext))
#     define DATAEND (&_end)
#     define STACK_GROWS_DOWN
#     define HEURISTIC2
#     include <unistd.h>
#     define GETPAGESIZE()  sysconf(_SC_PAGESIZE)
#     define DYNAMIC_LOADING
#     ifndef USE_MMAP
#       define USE_MMAP
#     endif /* USE_MMAP */
#     define MAP_FAILED (void *) -1
#     ifdef USE_MMAP
#       define HEAP_START (ptr_t)0x40000000
#     else /* USE_MMAP */
#       define HEAP_START DATAEND
#     endif /* USE_MMAP */
#   endif /* DGUX */

#   ifdef LINUX
#     define OS_TYPE "LINUX"
#       define LINUX_STACKBOTTOM
#     if 0
#       define HEURISTIC1
#         undef STACK_GRAN
#         define STACK_GRAN 0x10000000
        /* STACKBOTTOM is usually 0xc0000000, but this changes with     */
        /* different kernel configurations.  In particular, systems     */
        /* with 2GB physical memory will usually move the user    */
        /* address space limit, and hence initial SP to 0x80000000.     */
#       endif
#       if !defined(GC_LINUX_THREADS) || !defined(REDIRECT_MALLOC)
#         define MPROTECT_VDB
#     else
          /* We seem to get random errors in incremental mode,    */
          /* possibly because Linux threads is itself a malloc client */
          /* and can't deal with the signals.                     */
#     endif
#     define HEAP_START (ptr_t)0x1000
            /* This encourages mmap to give us low addresses,     */
            /* thus allowing the heap to grow to ~3GB       */
#       ifdef __ELF__
#            define DYNAMIC_LOADING
#          ifdef UNDEFINED    /* includes ro data */
             extern int _etext[];
#              define DATASTART ((ptr_t)((((word) (_etext)) + 0xfff) & ~0xfff))
#          endif
#          include <features.h>
#          if defined(__GLIBC__) && __GLIBC__ >= 2
#            define SEARCH_FOR_DATA_START
#          else
               extern char **__environ;
#                define DATASTART ((ptr_t)(&__environ))
                        /* hideous kludge: __environ is the first */
                        /* word in crt0.o, and delimits the start */
                        /* of the data segment, no matter which   */
                        /* ld options were passed through.        */
                        /* We could use _etext instead, but that  */
                        /* would include .rodata, which may       */
                        /* contain large read-only data tables    */
                        /* that we'd rather not scan.       */
#          endif
           extern int _end[];
#          define DATAEND (_end)
#     else
           extern int etext[];
#            define DATASTART ((ptr_t)((((word) (etext)) + 0xfff) & ~0xfff))
#       endif
#     ifdef USE_I686_PREFETCH
        /* FIXME: Thus should use __builtin_prefetch, but we'll leave that    */
        /* for the next rtelease.                                 */
#       define PREFETCH(x) \
          __asm__ __volatile__ ("   prefetchnta %0": : "m"(*(char *)(x)))
          /* Empirically prefetcht0 is much more effective at reducing  */
          /* cache miss stalls for the targetted load instructions.  But it   */
          /* seems to interfere enough with other cache traffic that the net  */
          /* result is worse than prefetchnta.                    */
#         if 0 
          /* Using prefetches for write seems to have a slight negative */
          /* impact on performance, at least for a PIII/500.                  */
#         define PREFETCH_FOR_WRITE(x) \
            __asm__ __volatile__ (" prefetcht0  %0": : "m"(*(char *)(x)))
#       endif
#     endif
#     ifdef USE_3DNOW_PREFETCH
#       define PREFETCH(x) \
          __asm__ __volatile__ ("   prefetch    %0": : "m"(*(char *)(x)))
#       define PREFETCH_FOR_WRITE(x) \
          __asm__ __volatile__ ("   prefetchw   %0": : "m"(*(char *)(x)))
#     endif
#   endif
#   ifdef CYGWIN32
#       define OS_TYPE "CYGWIN32"
#       define DATASTART ((ptr_t)GC_DATASTART)  /* From gc.h */
#       define DATAEND   ((ptr_t)GC_DATAEND)
#     undef STACK_GRAN
#       define STACK_GRAN 0x10000
#       define HEURISTIC1
#   endif
#   ifdef OS2
#     define OS_TYPE "OS2"
            /* STACKBOTTOM and DATASTART are handled specially in       */
            /* os_dep.c. OS2 actually has the right               */
            /* system call!                                 */
#     define DATAEND    /* not needed */
#   endif
#   ifdef MSWIN32
#     define OS_TYPE "MSWIN32"
            /* STACKBOTTOM and DATASTART are handled specially in       */
            /* os_dep.c.                                    */
#       if !defined(__WATCOMC__)
#       define MPROTECT_VDB
        /* We also avoided doing this in the past with GC_WIN32_THREADS */
        /* Hopefully that's fixed.                            */
#     endif
#     if _MSC_VER >= 1300  /* .NET, i.e. > VisualStudio 6   */
#         define GWW_VDB
#     endif
#       define DATAEND  /* not needed */
#   endif
#   ifdef MSWINCE
#     define OS_TYPE "MSWINCE"
#       define DATAEND  /* not needed */
#   endif
#   ifdef DJGPP
#       define OS_TYPE "DJGPP"
#       include "stubinfo.h"
        extern int etext[];
        extern int _stklen;
        extern int __djgpp_stack_limit;
#       define DATASTART ((ptr_t)((((word) (etext)) + 0x1ff) & ~0x1ff))
/* #       define STACKBOTTOM ((ptr_t)((word) _stubinfo + _stubinfo->size \
                                                     + _stklen)) */
#       define STACKBOTTOM ((ptr_t)((word) __djgpp_stack_limit + _stklen))
            /* This may not be right.  */
#   endif
#   ifdef OPENBSD
#     define OS_TYPE "OPENBSD"
#   endif
#   ifdef FREEBSD
#     define OS_TYPE "FREEBSD"
#     ifndef GC_FREEBSD_THREADS
#         define MPROTECT_VDB
#     endif
#     ifdef __GLIBC__
#         define SIG_SUSPEND        (32+6)
#         define SIG_THR_RESTART    (32+5)
          extern int _end[];
#         define DATAEND (_end)
#     else
#         define SIG_SUSPEND SIGUSR1
#         define SIG_THR_RESTART SIGUSR2
#     endif
#     define FREEBSD_STACKBOTTOM
#     ifdef __ELF__
#         define DYNAMIC_LOADING
#     endif
      extern char etext[];
      extern char * GC_FreeBSDGetDataStart(size_t, ptr_t);
#     define DATASTART GC_FreeBSDGetDataStart(0x1000, (ptr_t)etext)
#   endif
#   ifdef NETBSD
#     define OS_TYPE "NETBSD"
#     ifdef __ELF__
#         define DYNAMIC_LOADING
#     endif
#   endif
#   ifdef THREE86BSD
#     define OS_TYPE "THREE86BSD"
#   endif
#   ifdef BSDI
#     define OS_TYPE "BSDI"
#   endif
#   if defined(OPENBSD) || defined(NETBSD) \
        || defined(THREE86BSD) || defined(BSDI)
#     define HEURISTIC2
      extern char etext[];
#     define DATASTART ((ptr_t)(etext))
#   endif
#   ifdef NEXT
#     define OS_TYPE "NEXT"
#     define DATASTART ((ptr_t) get_etext())
#     define STACKBOTTOM ((ptr_t)0xc0000000)
#     define DATAEND    /* not needed */
#   endif
#   ifdef DOS4GW
#     define OS_TYPE "DOS4GW"
      extern long __nullarea;
      extern char _end;
      extern char *_STACKTOP;
      /* Depending on calling conventions Watcom C either precedes
         or does not precedes with undescore names of C-variables.
         Make sure startup code variables always have the same names.  */
      #pragma aux __nullarea "*";
      #pragma aux _end "*";
#     define STACKBOTTOM ((ptr_t) _STACKTOP)
                         /* confused? me too. */
#     define DATASTART ((ptr_t) &__nullarea)
#     define DATAEND ((ptr_t) &_end)
#   endif
#   ifdef HURD
#     define OS_TYPE "HURD"
#     define STACK_GROWS_DOWN
#     define HEURISTIC2
#     define SIG_SUSPEND SIGUSR1
#     define SIG_THR_RESTART SIGUSR2
#     define SEARCH_FOR_DATA_START
      extern int _end[];
#     define DATAEND ((ptr_t) (_end))
/* #     define MPROTECT_VDB  Not quite working yet? */
#     define DYNAMIC_LOADING
#   endif
#   ifdef DARWIN
#     define OS_TYPE "DARWIN"
#     define DARWIN_DONT_PARSE_STACK
#     define DYNAMIC_LOADING
      /* XXX: see get_end(3), get_etext() and get_end() should not be used.
       These aren't used when dyld support is enabled (it is by default) */
#     define DATASTART ((ptr_t) get_etext())
#     define DATAEND    ((ptr_t) get_end())
#     define STACKBOTTOM ((ptr_t) 0xc0000000)
#     define USE_MMAP
#     define USE_MMAP_ANON
#     ifdef GC_DARWIN_THREADS
#       define MPROTECT_VDB
#     endif
#     include <unistd.h>
#     define GETPAGESIZE() getpagesize()
      /* There seems to be some issues with trylock hanging on darwin. This
       should be looked into some more */
#      define NO_PTHREAD_TRYLOCK
#   endif /* DARWIN */
# endif

# ifdef NS32K
#   define MACH_TYPE "NS32K"
#   define ALIGNMENT 4
    extern char **environ;
#   define DATASTART ((ptr_t)(&environ))
                        /* hideous kludge: environ is the first   */
                        /* word in crt0.o, and delimits the start */
                        /* of the data segment, no matter which   */
                        /* ld options were passed through.        */
#   define STACKBOTTOM ((ptr_t) 0xfffff000) /* for Encore */
# endif

# ifdef MIPS
#   define MACH_TYPE "MIPS"
#   ifdef LINUX
#     define OS_TYPE "LINUX"
#     define DYNAMIC_LOADING
      extern int _end[];
#     define DATAEND (_end)
#     define SEARCH_FOR_DATA_START
#     define CPP_WORDSZ _MIPS_SZPTR
#     define ALIGNMENT (_MIPS_SZPTR/8)
#     if __GLIBC__ == 2 && __GLIBC_MINOR__ >= 2 || __GLIBC__ > 2
#       define LINUX_STACKBOTTOM
#     else
#       define STACKBOTTOM ((ptr_t)0x7fff8000)
#     endif
#   endif /* Linux */
#   ifdef EWS4800
#      define HEURISTIC2
#      if defined(_MIPS_SZPTR) && (_MIPS_SZPTR == 64)
         extern int _fdata[], _end[];
#        define DATASTART ((ptr_t)_fdata)
#        define DATAEND ((ptr_t)_end)
#        define CPP_WORDSZ _MIPS_SZPTR
#        define ALIGNMENT (_MIPS_SZPTR/8)
#      else
         extern int etext[], edata[], end[];
         extern int _DYNAMIC_LINKING[], _gp[];
#        define DATASTART ((ptr_t)((((word)etext + 0x3ffff) & ~0x3ffff) \
               + ((word)etext & 0xffff)))
#        define DATAEND (edata)
#        define DATASTART2 (_DYNAMIC_LINKING \
               ? (ptr_t)(((word)_gp + 0x8000 + 0x3ffff) & ~0x3ffff) \
               : (ptr_t)edata)
#        define DATAEND2 (end)
#        define ALIGNMENT 4
#      endif
#      define OS_TYPE "EWS4800"
#   endif
#   ifdef ULTRIX
#     define HEURISTIC2
#       define DATASTART (ptr_t)0x10000000
                        /* Could probably be slightly higher since */
                        /* startup code allocates lots of stuff.   */
#     define OS_TYPE "ULTRIX"
#       define ALIGNMENT 4
#   endif
#   ifdef IRIX5
#     define HEURISTIC2
        extern int _fdata[];
#       define DATASTART ((ptr_t)(_fdata))
#       ifdef USE_MMAP
#         define HEAP_START (ptr_t)0x30000000
#       else
#       define HEAP_START DATASTART
#       endif
                        /* Lowest plausible heap address.         */
                        /* In the MMAP case, we map there.  */
                        /* In either case it is used to identify  */
                        /* heap sections so they're not           */
                        /* considered as roots.             */
#     define OS_TYPE "IRIX5"
/*#       define MPROTECT_VDB DOB: this should work, but there is evidence */
/*          of recent breakage.                                */
#       ifdef _MIPS_SZPTR
#       define CPP_WORDSZ _MIPS_SZPTR
#       define ALIGNMENT (_MIPS_SZPTR/8)
#     else
#         define ALIGNMENT 4
#     endif
#     define DYNAMIC_LOADING
#   endif
#   ifdef MSWINCE
#       define OS_TYPE "MSWINCE"
#       define ALIGNMENT 4
#       define DATAEND /* not needed */
#   endif
#   if defined(NETBSD)
#     define OS_TYPE "NETBSD"
#     define ALIGNMENT 4
#     define HEURISTIC2
#     ifdef __ELF__
        extern int etext[];
#       define DATASTART GC_data_start
#       define NEED_FIND_LIMIT
#       define DYNAMIC_LOADING
#     else
#       define DATASTART ((ptr_t) 0x10000000)
#       define STACKBOTTOM ((ptr_t) 0x7ffff000)
#     endif /* _ELF_ */
#  endif
#  if defined(NONSTOP)
#    define CPP_WORDSZ 32
#    define OS_TYPE "NONSTOP"
#    define ALIGNMENT 4
#    define DATASTART ((ptr_t) 0x08000000)
     extern char **environ;
#    define DATAEND ((ptr_t)(environ - 0x10))
#    define STACKBOTTOM ((ptr_t) 0x4fffffff)
#   endif
# endif

# ifdef HP_PA
#   define MACH_TYPE "HP_PA"
#   ifdef __LP64__
#     define CPP_WORDSZ 64
#     define ALIGNMENT 8
#   else
#     define CPP_WORDSZ 32
#     define ALIGNMENT 4
#   endif
#   if !defined(GC_HPUX_THREADS) && !defined(GC_LINUX_THREADS)
#     ifndef LINUX /* For now. */
#       define MPROTECT_VDB
#     endif
#   else
#     ifdef PARALLEL_MARK
#     define USE_MARK_BYTES
            /* Minimize compare-and-swap usage.       */
#     endif
#   endif
#   define STACK_GROWS_UP
#   ifdef HPUX
#     define OS_TYPE "HPUX"
      extern int __data_start[];
#     define DATASTART ((ptr_t)(__data_start))
#     if 0
      /* The following appears to work for 7xx systems running HP/UX    */
      /* 9.xx Furthermore, it might result in much faster         */
      /* collections than HEURISTIC2, which may involve scanning  */
      /* segments that directly precede the stack.  It is not the */
      /* default, since it may not work on older machine/OS       */
      /* combinations. (Thanks to Raymond X.T. Nijssen for uncovering   */
      /* this.)                                       */
#       define STACKBOTTOM ((ptr_t) 0x7b033000)  /* from /etc/conf/h/param.h */
#     else
      /* Gustavo Rodriguez-Rivera suggested changing HEURISTIC2   */
      /* to this.  Note that the GC must be initialized before the      */
      /* first putenv call.                                 */
      extern char ** environ;
#       define STACKBOTTOM ((ptr_t)environ)
#     endif
#     define DYNAMIC_LOADING
#     include <unistd.h>
#     define GETPAGESIZE() sysconf(_SC_PAGE_SIZE)
#     ifndef __GNUC__
#       define PREFETCH(x)  { \
                              register long addr = (long)(x); \
                              (void) _asm ("LDW", 0, 0, addr, 0); \
                            }
#     endif
#   endif /* HPUX */
#   ifdef LINUX
#     define OS_TYPE "LINUX"
#     define LINUX_STACKBOTTOM
#     define DYNAMIC_LOADING
#     define SEARCH_FOR_DATA_START
      extern int _end[];
#     define DATAEND (&_end)
#   endif /* LINUX */
# endif /* HP_PA */

# ifdef ALPHA
#   define MACH_TYPE "ALPHA"
#   define ALIGNMENT 8
#   define CPP_WORDSZ 64
#   ifdef NETBSD
#     define OS_TYPE "NETBSD"
#     define HEURISTIC2
#     define DATASTART GC_data_start
#     define ELFCLASS32 32
#     define ELFCLASS64 64
#     define ELF_CLASS ELFCLASS64
#       define DYNAMIC_LOADING
#   endif
#   ifdef OPENBSD
#     define OS_TYPE "OPENBSD"
#     define HEURISTIC2
#     ifdef __ELF__     /* since OpenBSD/Alpha 2.9 */
#        define DATASTART GC_data_start
#        define ELFCLASS32 32
#        define ELFCLASS64 64
#        define ELF_CLASS ELFCLASS64
#       else            /* ECOFF, until OpenBSD/Alpha 2.7 */
#        define DATASTART ((ptr_t) 0x140000000)
#     endif
#   endif
#   ifdef FREEBSD
#     define OS_TYPE "FREEBSD"
/* MPROTECT_VDB is not yet supported at all on FreeBSD/alpha. */
#     define SIG_SUSPEND SIGUSR1
#     define SIG_THR_RESTART SIGUSR2
#     define FREEBSD_STACKBOTTOM
#     ifdef __ELF__
#         define DYNAMIC_LOADING
#     endif
/* Handle unmapped hole alpha*-*-freebsd[45]* puts between etext and edata. */
      extern char etext[];
      extern char edata[];
      extern char end[];
#     define NEED_FIND_LIMIT
#     define DATASTART ((ptr_t)(&etext))
#     define DATAEND (GC_find_limit (DATASTART, TRUE))
#     define DATASTART2 ((ptr_t)(&edata))
#     define DATAEND2 ((ptr_t)(&end))
#   endif
#   ifdef OSF1
#     define OS_TYPE "OSF1"
#     define DATASTART ((ptr_t) 0x140000000)
      extern int _end[];
#     define DATAEND ((ptr_t) &_end)
      extern char ** environ;
      /* round up from the value of environ to the nearest page boundary */
      /* Probably breaks if putenv is called before collector        */
      /* initialization.                                       */
#     define STACKBOTTOM ((ptr_t)(((word)(environ) | (getpagesize()-1))+1))
/* #        define HEURISTIC2 */
      /* Normally HEURISTIC2 is too conervative, since            */
      /* the text segment immediately follows the stack.          */
      /* Hence we give an upper pound.                      */
      /* This is currently unused, since we disabled HEURISTIC2   */
      extern int __start[];
#     define HEURISTIC2_LIMIT ((ptr_t)((word)(__start) & ~(getpagesize()-1)))
#     ifndef GC_OSF1_THREADS
        /* Unresolved signal issues with threads.     */
#       define MPROTECT_VDB
#       endif
#     define DYNAMIC_LOADING
#   endif
#   ifdef LINUX
#       define OS_TYPE "LINUX"
#       define LINUX_STACKBOTTOM
#       ifdef __ELF__
#       define SEARCH_FOR_DATA_START
#         define DYNAMIC_LOADING
#       else
#           define DATASTART ((ptr_t) 0x140000000)
#       endif
      extern int _end[];
#     define DATAEND (_end)
#     define MPROTECT_VDB
            /* Has only been superficially tested.  May not */
            /* work on all versions.                  */
#   endif
# endif

# ifdef IA64
#   define MACH_TYPE "IA64"
#   ifdef HPUX
#     ifdef _ILP32
#       define CPP_WORDSZ 32
          /* Requires 8 byte alignment for malloc */
#       define ALIGNMENT 4
#       else
#       ifndef _LP64
            ---> unknown ABI
#         endif
#       define CPP_WORDSZ 64
          /* Requires 16 byte alignment for malloc */
#         define ALIGNMENT 8
#       endif
#       define OS_TYPE "HPUX" 
        extern int __data_start[];
#       define DATASTART ((ptr_t)(__data_start))
        /* Gustavo Rodriguez-Rivera suggested changing HEURISTIC2 */
        /* to this.  Note that the GC must be initialized before the    */
      /* first putenv call.                                 */
      extern char ** environ;
#       define STACKBOTTOM ((ptr_t)environ)
#       define HPUX_STACKBOTTOM
#       define DYNAMIC_LOADING
#       include <unistd.h>
#       define GETPAGESIZE() sysconf(_SC_PAGE_SIZE)
      /* The following was empirically determined, and is probably      */
      /* not very robust.                                   */
      /* Note that the backing store base seems to be at a nice   */
      /* address minus one page.                            */
#     define BACKING_STORE_DISPLACEMENT 0x1000000
#     define BACKING_STORE_ALIGNMENT 0x1000
      extern ptr_t GC_register_stackbottom;
#     define BACKING_STORE_BASE GC_register_stackbottom
      /* Known to be wrong for recent HP/UX versions!!!     */
#   endif
#   ifdef LINUX
#     define CPP_WORDSZ 64
#     define ALIGNMENT 8
#       define OS_TYPE "LINUX"
      /* The following works on NUE and older kernels:      */
/* #       define STACKBOTTOM ((ptr_t) 0xa000000000000000l) */
      /* This does not work on NUE:                   */
#       define LINUX_STACKBOTTOM
      /* We also need the base address of the register stack      */
      /* backing store.  This is computed in                */
      /* GC_linux_register_stack_base based on the following      */
      /* constants:                                   */
#       define BACKING_STORE_ALIGNMENT 0x100000
#       define BACKING_STORE_DISPLACEMENT 0x80000000
      extern ptr_t GC_register_stackbottom;
#     define BACKING_STORE_BASE GC_register_stackbottom
#     define SEARCH_FOR_DATA_START
#     ifdef __GNUC__
#         define DYNAMIC_LOADING
#     else
        /* In the Intel compiler environment, we seem to end up with  */
        /* statically linked executables and an undefined reference     */
        /* to _DYNAMIC                                */
#     endif
#     define MPROTECT_VDB
            /* Requires Linux 2.3.47 or later.  */
      extern int _end[];
#     define DATAEND (_end)
#       ifdef __GNUC__
#       ifndef __INTEL_COMPILER
#         define PREFETCH(x) \
            __asm__ ("  lfetch      [%0]": : "r"(x))
#         define PREFETCH_FOR_WRITE(x) \
            __asm__ ("  lfetch.excl [%0]": : "r"(x))
#         define CLEAR_DOUBLE(x) \
            __asm__ ("  stf.spill   [%0]=f0": : "r"((void *)(x)))
#       else
#           include <ia64intrin.h>
#         define PREFETCH(x) \
            __lfetch(__lfhint_none, (x))
#         define PREFETCH_FOR_WRITE(x) \
            __lfetch(__lfhint_nta,  (x))
#         define CLEAR_DOUBLE(x) \
            __stf_spill((void *)(x), 0)
#       endif /* __INTEL_COMPILER */
#       endif
#   endif
#   ifdef MSWIN32
      /* FIXME: This is a very partial guess.  There is no port, yet.   */
#     define OS_TYPE "MSWIN32"
            /* STACKBOTTOM and DATASTART are handled specially in       */
            /* os_dep.c.                                    */
#     define DATAEND  /* not needed */
#     if defined(_WIN64)
#       define CPP_WORDSZ 64
#     else
#       define CPP_WORDSZ 32   /* Is this possible?   */
#     endif
#     define ALIGNMENT 8
#     define STRTOULL _strtoui64
#   endif
# endif

# ifdef M88K
#   define MACH_TYPE "M88K"
#   define ALIGNMENT 4
    extern int etext[];
#   ifdef CX_UX
#     define OS_TYPE "CX_UX"
#       define DATASTART ((((word)etext + 0x3fffff) & ~0x3fffff) + 0x10000)
#   endif
#   ifdef  DGUX
#     define OS_TYPE "DGUX"
      extern ptr_t GC_SysVGetDataStart(size_t, ptr_t);
#       define DATASTART GC_SysVGetDataStart(0x10000, (ptr_t)etext)
#   endif
#   define STACKBOTTOM ((char*)0xf0000000) /* determined empirically */
# endif

# ifdef S370
    /* If this still works, and if anyone cares, this should probably   */
    /* be moved to the S390 category.                             */
#   define MACH_TYPE "S370"
#   define ALIGNMENT 4  /* Required by hardware */
#   ifdef UTS4
#       define OS_TYPE "UTS4"
      extern int etext[];
      extern int _etext[];
      extern int _end[];
      extern ptr_t GC_SysVGetDataStart(size_t, ptr_t);
#       define DATASTART GC_SysVGetDataStart(0x10000, (ptr_t)_etext)
#     define DATAEND (_end)
#     define HEURISTIC2
#   endif
# endif

# ifdef S390
#   define MACH_TYPE "S390"
#   ifndef __s390x__
#   define ALIGNMENT 4
#   define CPP_WORDSZ 32
#   else
#   define ALIGNMENT 8
#   define CPP_WORDSZ 64
#   ifndef HBLKSIZE
#     define HBLKSIZE 4096
#   endif
#   endif
#   ifdef LINUX
#       define OS_TYPE "LINUX"
#       define LINUX_STACKBOTTOM
#       define DYNAMIC_LOADING
#       define SEARCH_FOR_DATA_START
        extern int _end[];
#   define DATAEND (_end)
#   define CACHE_LINE_SIZE 256
#   define GETPAGESIZE() 4096
#   endif
# endif

# ifdef ARM32
#   define CPP_WORDSZ 32
#   define MACH_TYPE "ARM32"
#   define ALIGNMENT 4
#   ifdef NETBSD
#       define OS_TYPE "NETBSD"
#       define HEURISTIC2
#     ifdef __ELF__
#          define DATASTART GC_data_start
#        define DYNAMIC_LOADING
#     else
           extern char etext[];
#          define DATASTART ((ptr_t)(etext))
#     endif
#   endif
#   ifdef LINUX
#       define OS_TYPE "LINUX"
#       define LINUX_STACKBOTTOM
#       undef STACK_GRAN
#       define STACK_GRAN 0x10000000
#       ifdef __ELF__
#            define DYNAMIC_LOADING
#          include <features.h>
#          if defined(__GLIBC__) && __GLIBC__ >= 2
#            define SEARCH_FOR_DATA_START
#          else
               extern char **__environ;
#                define DATASTART ((ptr_t)(&__environ))
                        /* hideous kludge: __environ is the first */
                        /* word in crt0.o, and delimits the start */
                        /* of the data segment, no matter which   */
                        /* ld options were passed through.        */
                        /* We could use _etext instead, but that  */
                        /* would include .rodata, which may       */
                        /* contain large read-only data tables    */
                        /* that we'd rather not scan.       */
#          endif
           extern int _end[];
#          define DATAEND (_end)
#     else
           extern int etext[];
#            define DATASTART ((ptr_t)((((word) (etext)) + 0xfff) & ~0xfff))
#       endif
#   endif
#   ifdef MSWINCE
#     define OS_TYPE "MSWINCE"
#     define DATAEND /* not needed */
#   endif
#   ifdef NOSYS
      /* __data_start is usually defined in the target linker script.  */
      extern int __data_start[];
#     define DATASTART (ptr_t)(__data_start)
      /* __stack_base__ is set in newlib/libc/sys/arm/crt0.S  */
      extern void *__stack_base__;
#     define STACKBOTTOM ((ptr_t) (__stack_base__))
#   endif
#endif

# ifdef CRIS
#   define MACH_TYPE "CRIS"
#   define CPP_WORDSZ 32
#   define ALIGNMENT 1
#   define OS_TYPE "LINUX"
#   define DYNAMIC_LOADING
#   define LINUX_STACKBOTTOM
#   define SEARCH_FOR_DATA_START
      extern int _end[];
#   define DATAEND (_end)
# endif

# ifdef SH
#   define MACH_TYPE "SH"
#   define ALIGNMENT 4
#   ifdef MSWINCE
#     define OS_TYPE "MSWINCE"
#     define DATAEND /* not needed */
#   endif
#   ifdef LINUX
#     define OS_TYPE "LINUX"
#     define LINUX_STACKBOTTOM
#     define DYNAMIC_LOADING
#     define SEARCH_FOR_DATA_START
      extern int _end[];
#     define DATAEND (_end)
#   endif
#   ifdef NETBSD
#      define OS_TYPE "NETBSD"
#      define HEURISTIC2
#      define DATASTART GC_data_start
#      define DYNAMIC_LOADING
#   endif
# endif
 
# ifdef SH4
#   define MACH_TYPE "SH4"
#   define OS_TYPE "MSWINCE"
#   define ALIGNMENT 4
#   define DATAEND /* not needed */
# endif

# ifdef M32R
#   define CPP_WORDSZ 32
#   define MACH_TYPE "M32R"
#   define ALIGNMENT 4
#   ifdef LINUX
#     define OS_TYPE "LINUX"
#     define LINUX_STACKBOTTOM
#     undef STACK_GRAN
#     define STACK_GRAN 0x10000000
#     define DYNAMIC_LOADING
#     define SEARCH_FOR_DATA_START
      extern int _end[];
#     define DATAEND (_end)
#   endif
# endif

# ifdef X86_64
#   define MACH_TYPE "X86_64"
#   define ALIGNMENT 8
#   define CPP_WORDSZ 64
#   ifndef HBLKSIZE
#     define HBLKSIZE 4096
#   endif
#   define CACHE_LINE_SIZE 64
#   ifdef LINUX
#     define OS_TYPE "LINUX"
#       define LINUX_STACKBOTTOM
#       if !defined(GC_LINUX_THREADS) || !defined(REDIRECT_MALLOC)
#         define MPROTECT_VDB
#     else
          /* We seem to get random errors in incremental mode,    */
          /* possibly because Linux threads is itself a malloc client */
          /* and can't deal with the signals.                     */
#     endif
#       ifdef __ELF__
#            define DYNAMIC_LOADING
#          ifdef UNDEFINED    /* includes ro data */
             extern int _etext[];
#              define DATASTART ((ptr_t)((((word) (_etext)) + 0xfff) & ~0xfff))
#          endif
#          include <features.h>
#          define SEARCH_FOR_DATA_START
           extern int _end[];
#          define DATAEND (_end)
#     else
           extern int etext[];
#            define DATASTART ((ptr_t)((((word) (etext)) + 0xfff) & ~0xfff))
#       endif
#       if defined(__GNUC__) && __GNUC__ >= 3
#         define PREFETCH(x) __builtin_prefetch((x), 0, 0)
#         define PREFETCH_FOR_WRITE(x) __builtin_prefetch((x), 1)
#     endif
#   endif
#   ifdef DARWIN
#     define OS_TYPE "DARWIN"
#     define DARWIN_DONT_PARSE_STACK
#     define DYNAMIC_LOADING
      /* XXX: see get_end(3), get_etext() and get_end() should not be used.
       These aren't used when dyld support is enabled (it is by default) */
#     define DATASTART ((ptr_t) get_etext())
#     define DATAEND    ((ptr_t) get_end())
#     define STACKBOTTOM ((ptr_t) 0x7fff5fc00000)
#     define USE_MMAP
#     define USE_MMAP_ANON
#     ifdef GC_DARWIN_THREADS
#       define MPROTECT_VDB
#     endif
#     include <unistd.h>
#     define GETPAGESIZE() getpagesize()
      /* There seems to be some issues with trylock hanging on darwin. This
       should be looked into some more */
#     define NO_PTHREAD_TRYLOCK
#   endif
#   ifdef FREEBSD
#     define OS_TYPE "FREEBSD"
#     ifndef GC_FREEBSD_THREADS
#         define MPROTECT_VDB
#     endif
#     ifdef __GLIBC__
#         define SIG_SUSPEND        (32+6)
#         define SIG_THR_RESTART    (32+5)
          extern int _end[];
#         define DATAEND (_end)
#     else
#         define SIG_SUSPEND SIGUSR1
#         define SIG_THR_RESTART SIGUSR2
#     endif
#     define FREEBSD_STACKBOTTOM
#     ifdef __ELF__
#         define DYNAMIC_LOADING
#     endif
      extern char etext[];
      extern char * GC_FreeBSDGetDataStart();
#     define DATASTART GC_FreeBSDGetDataStart(0x1000, &etext)
#   endif
#   ifdef NETBSD
#     define OS_TYPE "NETBSD"
#     ifdef __ELF__
#         define DYNAMIC_LOADING
#     endif
#     define HEURISTIC2
      extern char etext[];
#     define SEARCH_FOR_DATA_START
#   endif
#   ifdef SOLARIS
#     define OS_TYPE "SOLARIS"
#     define ELF_CLASS ELFCLASS64
        extern int _etext[], _end[];
      extern ptr_t GC_SysVGetDataStart(size_t, ptr_t);
#       define DATASTART GC_SysVGetDataStart(0x1000, (ptr_t)_etext)
#     define DATAEND (_end)
/*    # define STACKBOTTOM ((ptr_t)(_start)) worked through 2.7,        */
/*      but reportedly breaks under 2.8.  It appears that the stack     */
/*    base is a property of the executable, so this should not break    */
/*    old executables.                                */
/*    HEURISTIC2 probably works, but this appears to be preferable.     */
/*    Apparently USRSTACK is defined to be USERLIMIT, but in some */
/*    installations that's undefined.  We work around this with a */
/*    gross hack:                                     */
#       include <sys/vmparam.h>
#     ifdef USERLIMIT
        /* This should work everywhere, but doesn't.  */
#       define STACKBOTTOM USRSTACK
#       else
#       define HEURISTIC2
#       endif
/* At least in Solaris 2.5, PROC_VDB gives wrong values for dirty bits. */
/* It appears to be fixed in 2.8 and 2.9.                   */
#     ifdef SOLARIS25_PROC_VDB_BUG_FIXED
#       define PROC_VDB
#     endif
#     define DYNAMIC_LOADING
#     if !defined(USE_MMAP) && defined(REDIRECT_MALLOC)
#         define USE_MMAP
          /* Otherwise we now use calloc.  Mmap may result in the */
          /* heap interleaved with thread stacks, which can result in   */
          /* excessive blacklisting.  Sbrk is unusable since it   */
          /* doesn't interact correctly with the system malloc.   */
#     endif
#       ifdef USE_MMAP
#         define HEAP_START (ptr_t)0x40000000
#       else
#       define HEAP_START DATAEND
#       endif
#   endif
#   ifdef MSWIN32
#     define OS_TYPE "MSWIN32"
            /* STACKBOTTOM and DATASTART are handled specially in       */
            /* os_dep.c.                                    */
#       if !defined(__WATCOMC__)
#       define MPROTECT_VDB
        /* We also avoided doing this in the past with GC_WIN32_THREADS */
        /* Hopefully that's fixed.                            */
#     endif
#     if _MSC_VER >= 1300  /* .NET, i.e. > VisualStudio 6   */
#         define GWW_VDB
#     endif
#       define DATAEND  /* not needed */
#   endif
# endif

#if defined(LINUX_STACKBOTTOM) && defined(NO_PROC_STAT) \
    && !defined(USE_LIBC_PRIVATES)
    /* This combination will fail, since we have no way to get    */
    /* the stack base.  Use HEURISTIC2 instead.             */
#   undef LINUX_STACKBOTTOM
#   define HEURISTIC2
    /* This may still fail on some architectures like IA64. */
    /* We tried ...                                   */
#endif

#if defined(LINUX) && defined(USE_MMAP)
    /* The kernel may do a somewhat better job merging mappings etc.    */
    /* with anonymous mappings.                                   */
#   define USE_MMAP_ANON
#endif

#if defined(GC_LINUX_THREADS) && defined(REDIRECT_MALLOC)
    /* Nptl allocates thread stacks with mmap, which is fine.  But it   */
    /* keeps a cache of thread stacks.  Thread stacks contain the */
    /* thread control blocks.  These in turn contain a pointer to */
    /* (sizeof (void *) from the beginning of) the dtv for thread-local */
    /* storage, which is calloc allocated.  If we don't scan the cached */
    /* thread stacks, we appear to lose the dtv.  This tends to         */
    /* result in something that looks like a bogus dtv count, which     */
    /* tends to result in a memset call on a block that is way too      */
    /* large.  Sometimes we're lucky and the process just dies ...      */
    /* There seems to be a similar issue with some other memory   */
    /* allocated by the dynamic loader.                           */
    /* This should be avoidable by either:                        */
    /* - Defining USE_PROC_FOR_LIBRARIES here.                    */
    /*   That performs very poorly, precisely because we end up   */
    /*   scanning cached stacks.                            */
    /* - Have calloc look at its callers.                         */
    /*   In spite of the fact that it is gross and disgusting.          */
    /* In fact neither seems to suffice, probably in part because       */
    /* even with USE_PROC_FOR_LIBRARIES, we don't scan parts of stack   */
    /* segments that appear to be out of bounds.  Thus we actually      */
    /* do both, which seems to yield the best results.                  */

#   define USE_PROC_FOR_LIBRARIES
#endif

# ifndef STACK_GROWS_UP
#   define STACK_GROWS_DOWN
# endif

# ifndef CPP_WORDSZ
#   define CPP_WORDSZ 32
# endif

# ifndef OS_TYPE
#   define OS_TYPE ""
# endif

# ifndef DATAEND
    extern int end[];
#   define DATAEND (end)
# endif

# if defined(SVR4) && !defined(GETPAGESIZE)
#    include <unistd.h>
#    define GETPAGESIZE()  sysconf(_SC_PAGESIZE)
# endif

# ifndef GETPAGESIZE
#   if defined(SOLARIS) || defined(IRIX5) || defined(LINUX) \
       || defined(NETBSD) || defined(FREEBSD) || defined(HPUX)
#     include <unistd.h>
#   endif
#   define GETPAGESIZE() getpagesize()
# endif

# if defined(SOLARIS) || defined(DRSNX) || defined(UTS4)
          /* OS has SVR4 generic features.            */
          /* Probably others also qualify.            */
#   define SVR4
# endif

# if defined(SOLARIS) || defined(DRSNX)
          /* OS has SOLARIS style semi-undocumented interface */
          /* to dynamic loader.                       */
#   define SOLARISDL
          /* OS has SOLARIS style signal handlers.          */
#   define SUNOS5SIGS
# endif

# if defined(HPUX)
#   define SUNOS5SIGS
# endif

# if defined(FREEBSD) && \
     (defined(__DragonFly__) || __FreeBSD__ >= 4 || (__FreeBSD_kernel__ >= 4))
#   define SUNOS5SIGS
# endif

# ifdef GC_NETBSD_THREADS
#   define SIGRTMIN 33
#   define SIGRTMAX 63
# endif

# if defined(SVR4) || defined(LINUX) || defined(IRIX5) || defined(HPUX) \
          || defined(OPENBSD) || defined(NETBSD) || defined(FREEBSD) \
          || defined(DGUX) || defined(BSD) \
          || defined(AIX) || defined(DARWIN) || defined(OSF1) \
          || defined(HURD)
#   define UNIX_LIKE   /* Basic Unix-like system calls work.      */
# endif

# if CPP_WORDSZ != 32 && CPP_WORDSZ != 64
         -> bad word size
# endif

# ifdef PCR
#   undef DYNAMIC_LOADING
#   undef STACKBOTTOM
#   undef HEURISTIC1
#   undef HEURISTIC2
#   undef PROC_VDB
#   undef MPROTECT_VDB
#   define PCR_VDB
# endif

# ifdef SMALL_CONFIG
      /* Presumably not worth the space it takes. */
#   undef PROC_VDB
#   undef MPROTECT_VDB
# endif

# ifdef USE_MUNMAP
#   undef MPROTECT_VDB  /* Can't deal with address space holes. */
# endif

# ifdef PARALLEL_MARK
#   undef MPROTECT_VDB  /* For now. */
# endif

# if !defined(PCR_VDB) && !defined(PROC_VDB) && !defined(MPROTECT_VDB) \
    && !defined(GWW_VDB)
#   define DEFAULT_VDB
# endif

# ifndef PREFETCH
#   define PREFETCH(x)
#   define NO_PREFETCH
# endif

# ifndef PREFETCH_FOR_WRITE
#   define PREFETCH_FOR_WRITE(x)
#   define NO_PREFETCH_FOR_WRITE
# endif

# ifndef CACHE_LINE_SIZE
#   define CACHE_LINE_SIZE 32 /* Wild guess     */
# endif

# if defined(LINUX) || defined(HURD) || defined(__GLIBC__)
#   define REGISTER_LIBRARIES_EARLY
    /* We sometimes use dl_iterate_phdr, which may acquire an internal  */
    /* lock.  This isn't safe after the world has stopped.  So we must  */
    /* call GC_register_dynamic_libraries before stopping the world.    */
    /* For performance reasons, this may be beneficial on other         */
    /* platforms as well, though it should be avoided in win32.         */
# endif /* LINUX */

# if defined(SEARCH_FOR_DATA_START)
    extern ptr_t GC_data_start;
#   define DATASTART GC_data_start
# endif

# ifndef CLEAR_DOUBLE
#   define CLEAR_DOUBLE(x) \
            ((word*)x)[0] = 0; \
            ((word*)x)[1] = 0;
# endif /* CLEAR_DOUBLE */

# if defined(GC_LINUX_THREADS) && defined(REDIRECT_MALLOC) \
     && !defined(INCLUDE_LINUX_THREAD_DESCR)
    /* Will not work, since libc and the dynamic loader use thread      */
    /* locals, sometimes as the only reference.                   */
#   define INCLUDE_LINUX_THREAD_DESCR
# endif

# if defined(GC_IRIX_THREADS) && !defined(IRIX5)
      --> inconsistent configuration
# endif
# if defined(GC_LINUX_THREADS) && !defined(LINUX)
      --> inconsistent configuration
# endif
# if defined(GC_NETBSD_THREADS) && !defined(NETBSD)
      --> inconsistent configuration
# endif
# if defined(GC_FREEBSD_THREADS) && !defined(FREEBSD)
      --> inconsistent configuration
# endif
# if defined(GC_SOLARIS_THREADS) && !defined(SOLARIS)
      --> inconsistent configuration
# endif
# if defined(GC_HPUX_THREADS) && !defined(HPUX)
      --> inconsistent configuration
# endif
# if defined(GC_AIX_THREADS) && !defined(_AIX)
      --> inconsistent configuration
# endif
# if defined(GC_GNU_THREADS) && !defined(HURD)
      --> inconsistent configuration
# endif
# if defined(GC_WIN32_THREADS) && !defined(MSWIN32) && !defined(CYGWIN32)
      --> inconsistent configuration
# endif

# if defined(PCR) || defined(GC_WIN32_THREADS) || defined(GC_PTHREADS)
#   define THREADS
# endif

# if !defined(USE_MARK_BITS) && !defined(USE_MARK_BYTES)
#   if defined(THREADS) && defined(PARALLEL_MARK)
#     define USE_MARK_BYTES
#   else
#     define USE_MARK_BITS
#   endif
# endif

# if defined(MSWINCE)
#   define NO_GETENV
# endif

# if defined(SPARC)
#   define ASM_CLEAR_CODE     /* Stack clearing is crucial, and we      */
                        /* include assembly code to do it well.   */
# endif

  /* Can we save call chain in objects for debugging?               */
  /* SET NFRAMES (# of saved frames) and NARGS (#of args for each       */
  /* frame) to reasonable values for the platform.                */
  /* Set SAVE_CALL_CHAIN if we can.  SAVE_CALL_COUNT can be specified   */
  /* at build time, though we feel free to adjust it slightly.          */
  /* Define NEED_CALLINFO if we either save the call stack or           */
  /* GC_ADD_CALLER is defined.                                    */
  /* GC_CAN_SAVE_CALL_STACKS is set in gc.h.                      */

#if defined(SPARC)
# define CAN_SAVE_CALL_ARGS
#endif
#if (defined(I386) || defined(X86_64)) && (defined(LINUX) || defined(__GLIBC__))
          /* SAVE_CALL_CHAIN is supported if the code is compiled to save     */
          /* frame pointers by default, i.e. no -fomit-frame-pointer flag.    */
# define CAN_SAVE_CALL_ARGS
#endif

# if defined(SAVE_CALL_COUNT) && !defined(GC_ADD_CALLER) \
           && defined(GC_CAN_SAVE_CALL_STACKS)
#   define SAVE_CALL_CHAIN 
# endif
# ifdef SAVE_CALL_CHAIN
#   if defined(SAVE_CALL_NARGS) && defined(CAN_SAVE_CALL_ARGS)
#     define NARGS SAVE_CALL_NARGS
#   else
#     define NARGS 0    /* Number of arguments to save for each call.   */
#   endif
# endif
# ifdef SAVE_CALL_CHAIN
#   ifndef SAVE_CALL_COUNT
#     define NFRAMES 6  /* Number of frames to save. Even for           */
                  /* alignment reasons.                     */
#   else
#     define NFRAMES ((SAVE_CALL_COUNT + 1) & ~1)
#   endif
#   define NEED_CALLINFO
# endif /* SAVE_CALL_CHAIN */
# ifdef GC_ADD_CALLER
#   define NFRAMES 1
#   define NARGS 0
#   define NEED_CALLINFO
# endif

# if defined(MAKE_BACK_GRAPH) && !defined(DBG_HDRS_ALL)
#   define DBG_HDRS_ALL
# endif

# if defined(POINTER_MASK) && !defined(POINTER_SHIFT)
#   define POINTER_SHIFT 0
# endif

# if defined(POINTER_SHIFT) && !defined(POINTER_MASK)
#   define POINTER_MASK ((GC_word)(-1))
# endif

# if !defined(FIXUP_POINTER) && defined(POINTER_MASK)
#   define FIXUP_POINTER(p) (p) = ((p) & (POINTER_MASK) << POINTER_SHIFT)
# endif

# if defined(FIXUP_POINTER)
#   define NEED_FIXUP_POINTER 1
# else
#   define NEED_FIXUP_POINTER 0
#   define FIXUP_POINTER(p)
# endif

# if !defined(MARK_BIT_PER_GRANULE) && !defined(MARK_BIT_PER_OBJ)
#   define MARK_BIT_PER_GRANULE     /* Usually faster */
# endif

/* Some static sanity tests.  */
# if defined(MARK_BIT_PER_GRANULE) && defined(MARK_BIT_PER_OBJ)
#   error Define only one of MARK_BIT_PER_GRANULE and MARK_BIT_PER_OBJ.
# endif

# if defined(STACK_GROWS_UP) && defined(STACK_GROWS_DOWN)
#   error "Only one of STACK_GROWS_UP and STACK_GROWS_DOWN should be defd."
# endif
# if !defined(STACK_GROWS_UP) && !defined(STACK_GROWS_DOWN)
#   error "One of STACK_GROWS_UP and STACK_GROWS_DOWN should be defd."
# endif

# if defined(REDIRECT_MALLOC) && defined(THREADS) && !defined(LINUX)
#   error "REDIRECT_MALLOC with THREADS works at most on Linux."
# endif

#ifdef GC_PRIVATE_H
      /* This relies on some type definitions from gc_priv.h, from      */
        /* where it's normally included.                    */
      /*                                              */
      /* How to get heap memory from the OS:                      */
      /* Note that sbrk()-like allocation is preferred, since it  */
      /* usually makes it possible to merge consecutively allocated     */
      /* chunks.  It also avoids unintented recursion with        */
      /* -DREDIRECT_MALLOC.                                 */
      /* GET_MEM() returns a HLKSIZE aligned chunk.               */
      /* 0 is taken to mean failure.                              */
      /* In the case os USE_MMAP, the argument must also be a     */
      /* physical page size.                                */
      /* GET_MEM is currently not assumed to retrieve 0 filled space, */
      /* though we should perhaps take advantage of the case in which */
      /* does.                                        */
      struct hblk;      /* See gc_priv.h. */
# if defined(PCR)
    char * real_malloc();
#   define GET_MEM(bytes) HBLKPTR(real_malloc((size_t)bytes + GC_page_size) \
                                + GC_page_size-1)
# elif defined(OS2)
    void * os2_alloc(size_t bytes);
#   define GET_MEM(bytes) HBLKPTR((ptr_t)os2_alloc((size_t)bytes \
                                  + GC_page_size) \
                                  + GC_page_size-1)
# elif defined(NEXT) || defined(DOS4GW) || defined(NONSTOP) || \
             (defined(AMIGA) && !defined(GC_AMIGA_FASTALLOC)) || \
             (defined(SOLARIS) && !defined(USE_MMAP))
#   define GET_MEM(bytes) HBLKPTR((size_t) calloc(1, (size_t)bytes + GC_page_size) \
                                           + GC_page_size-1)
# elif defined(MSWIN32)
    extern ptr_t GC_win32_get_mem();
#   define GET_MEM(bytes) (struct hblk *)GC_win32_get_mem(bytes)
# elif defined(MACOS)
#   if defined(USE_TEMPORARY_MEMORY)
      extern Ptr GC_MacTemporaryNewPtr(size_t size, Boolean clearMemory);
#     define GET_MEM(bytes) HBLKPTR( \
                      GC_MacTemporaryNewPtr(bytes + GC_page_size, true) \
                      + GC_page_size-1)
#   else
#     define GET_MEM(bytes) HBLKPTR( \
                        NewPtrClear(bytes + GC_page_size) + GC_page_size-1)
#   endif
# elif defined(MSWINCE)
    extern ptr_t GC_wince_get_mem();
#   define GET_MEM(bytes) (struct hblk *)GC_wince_get_mem(bytes)
# elif defined(AMIGA) && defined(GC_AMIGA_FASTALLOC)
    extern void *GC_amiga_get_mem(size_t size);
#   define GET_MEM(bytes) HBLKPTR((size_t) \
                    GC_amiga_get_mem((size_t)bytes + GC_page_size) \
                    + GC_page_size-1)
# else
    extern ptr_t GC_unix_get_mem();
#   define GET_MEM(bytes) (struct hblk *)GC_unix_get_mem(bytes)
# endif

#endif /* GC_PRIVATE_H */

# endif /* GCCONFIG_H */

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