gcconfig.h

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#   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, and if that fails read it from /proc.
 * 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))