boost_1_45_0/tools/build/v2/engine/src/boehm_gc/include/private/gc_pmark.h - nest-learning-thermostat/5.0/boost - Git at Google

 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 2001 by Hewlett-Packard Company. All rights reserved.
  *
  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
  *
  * Permission is hereby granted to use or copy this program
  * for any purpose,  provided the above notices are retained on all copies.
  * Permission to modify the code and to distribute modified code is granted,
  * provided the above notices are retained, and a notice that the code was
  * modified is included with the above copyright notice.
  *
  */

 /* Private declarations of GC marker data structures and macros */

 /*
  * Declarations of mark stack.  Needed by marker and client supplied mark
  * routines.  Transitively include gc_priv.h.
  * (Note that gc_priv.h should not be included before this, since this
  * includes dbg_mlc.h, which wants to include gc_priv.h AFTER defining
  * I_HIDE_POINTERS.)
  */
 #ifndef GC_PMARK_H
 # define GC_PMARK_H

 # if defined(KEEP_BACK_PTRS) || defined(PRINT_BLACK_LIST)
 #   include "dbg_mlc.h"
 # endif
 # ifndef GC_MARK_H
 #   include "../gc_mark.h"
 # endif
 # ifndef GC_PRIVATE_H
 #   include "gc_priv.h"
 # endif

 /* The real declarations of the following is in gc_priv.h, so that	*/
 /* we can avoid scanning the following table.				*/
 /*
 extern mark_proc GC_mark_procs[MAX_MARK_PROCS];
 */

 /*
  * Mark descriptor stuff that should remain private for now, mostly
  * because it's hard to export WORDSZ without including gcconfig.h.
  */
 # define BITMAP_BITS (WORDSZ - GC_DS_TAG_BITS)
 # define PROC(descr) \
 	(GC_mark_procs[((descr) >> GC_DS_TAG_BITS) & (GC_MAX_MARK_PROCS-1)])
 # define ENV(descr) \
 	((descr) >> (GC_DS_TAG_BITS + GC_LOG_MAX_MARK_PROCS))
 # define MAX_ENV \
   	(((word)1 << (WORDSZ - GC_DS_TAG_BITS - GC_LOG_MAX_MARK_PROCS)) - 1)


 extern unsigned GC_n_mark_procs;

 /* Number of mark stack entries to discard on overflow.	*/
 #define GC_MARK_STACK_DISCARDS (INITIAL_MARK_STACK_SIZE/8)

 typedef struct GC_ms_entry {
     ptr_t mse_start;   /* First word of object */
     GC_word mse_descr;	/* Descriptor; low order two bits are tags,	*/
     			/* identifying the upper 30 bits as one of the	*/
     			/* following:					*/
 } mse;

 extern size_t GC_mark_stack_size;

 extern mse * GC_mark_stack_limit;

 #ifdef PARALLEL_MARK
   extern mse * volatile GC_mark_stack_top;
 #else
   extern mse * GC_mark_stack_top;
 #endif

 extern mse * GC_mark_stack;

 #ifdef PARALLEL_MARK
     /*
      * Allow multiple threads to participate in the marking process.
      * This works roughly as follows:
      *  The main mark stack never shrinks, but it can grow.
      *
      *	The initiating threads holds the GC lock, and sets GC_help_wanted.
      *
      *  Other threads:
      *     1) update helper_count (while holding mark_lock.)
      *	   2) allocate a local mark stack
      *     repeatedly:
      *		3) Steal a global mark stack entry by atomically replacing
      *		   its descriptor with 0.
      *		4) Copy it to the local stack.
      *	        5) Mark on the local stack until it is empty, or
      *		   it may be profitable to copy it back.
      *	        6) If necessary, copy local stack to global one,
      *		   holding mark lock.
      *    7) Stop when the global mark stack is empty.
      *    8) decrement helper_count (holding mark_lock).
      *
      * This is an experiment to see if we can do something along the lines
      * of the University of Tokyo SGC in a less intrusive, though probably
      * also less performant, way.
      */
     void GC_do_parallel_mark();
 		/* inititate parallel marking.	*/

     extern GC_bool GC_help_wanted;	/* Protected by mark lock	*/
     extern unsigned GC_helper_count;	/* Number of running helpers.	*/
 					/* Protected by mark lock	*/
     extern unsigned GC_active_count;	/* Number of active helpers.	*/
 					/* Protected by mark lock	*/
 					/* May increase and decrease	*/
 					/* within each mark cycle.  But	*/
 					/* once it returns to 0, it	*/
 					/* stays zero for the cycle.	*/
     /* GC_mark_stack_top is also protected by mark lock.	*/
     /*
      * GC_notify_all_marker() is used when GC_help_wanted is first set,
      * when the last helper becomes inactive,
      * when something is added to the global mark stack, and just after
      * GC_mark_no is incremented.
      * This could be split into multiple CVs (and probably should be to
      * scale to really large numbers of processors.)
      */
 #endif /* PARALLEL_MARK */

 /* Return a pointer to within 1st page of object.  	*/
 /* Set *new_hdr_p to corr. hdr.				*/
 ptr_t GC_find_start(ptr_t current, hdr *hhdr, hdr **new_hdr_p);

 mse * GC_signal_mark_stack_overflow(mse *msp);

 /* Push the object obj with corresponding heap block header hhdr onto 	*/
 /* the mark stack.							*/
 # define PUSH_OBJ(obj, hhdr, mark_stack_top, mark_stack_limit) \
 { \
     register word _descr = (hhdr) -> hb_descr; \
         \
     if (_descr != 0) { \
         mark_stack_top++; \
         if (mark_stack_top >= mark_stack_limit) { \
           mark_stack_top = GC_signal_mark_stack_overflow(mark_stack_top); \
         } \
         mark_stack_top -> mse_start = (obj); \
         mark_stack_top -> mse_descr = _descr; \
     } \
 }

 /* Push the contents of current onto the mark stack if it is a valid	*/
 /* ptr to a currently unmarked object.  Mark it.			*/
 /* If we assumed a standard-conforming compiler, we could probably	*/
 /* generate the exit_label transparently.				*/
 # define PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, \
 		       source, exit_label) \
 { \
     hdr * my_hhdr; \
  \
     HC_GET_HDR(current, my_hhdr, source, exit_label); \
     PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
 		  source, exit_label, my_hhdr, TRUE);	\
 exit_label: ; \
 }

 /* Set mark bit, exit if it was already set.	*/

 # ifdef USE_MARK_BITS
 #   ifdef PARALLEL_MARK
       /* The following may fail to exit even if the bit was already set.    */
       /* For our uses, that's benign:                                       */
 #     define OR_WORD_EXIT_IF_SET(addr, bits, exit_label) \
         { \
           if (!(*(addr) & (mask))) { \
             AO_or((AO_t *)(addr), (mask); \
           } else { \
             goto label; \
           } \
         }
 #   else
 #     define OR_WORD_EXIT_IF_SET(addr, bits, exit_label) \
         { \
            word old = *(addr); \
            word my_bits = (bits); \
            if (old & my_bits) goto exit_label; \
            *(addr) = (old | my_bits); \
          }
 #   endif /* !PARALLEL_MARK */
 #   define SET_MARK_BIT_EXIT_IF_SET(hhdr,bit_no,exit_label) \
     { \
         word * mark_word_addr = hhdr -> hb_marks + divWORDSZ(bit_no); \
       \
         OR_WORD_EXIT_IF_SET(mark_word_addr, (word)1 << modWORDSZ(bit_no), \
                             exit_label); \
     }
 # endif


 #ifdef USE_MARK_BYTES
 # if defined(I386) && defined(__GNUC__)
 #  define LONG_MULT(hprod, lprod, x, y) { \
 	asm("mull %2" : "=a"(lprod), "=d"(hprod) : "g"(y), "0"(x)); \
    }
 # else /* No in-line X86 assembly code */
 #  define LONG_MULT(hprod, lprod, x, y) { \
 	unsigned long long prod = (unsigned long long)x \
 				  * (unsigned long long)y; \
 	hprod = prod >> 32;  \
 	lprod = (unsigned32)prod;  \
    }
 # endif

   /* There is a race here, and we may set				*/
   /* the bit twice in the concurrent case.  This can result in the	*/
   /* object being pushed twice.  But that's only a performance issue.	*/
 # define SET_MARK_BIT_EXIT_IF_SET(hhdr,bit_no,exit_label) \
     { \
         char * mark_byte_addr = (char *)hhdr -> hb_marks + (bit_no); \
         char mark_byte = *mark_byte_addr; \
           \
 	if (mark_byte) goto exit_label; \
 	*mark_byte_addr = 1;  \
     }
 #endif /* USE_MARK_BYTES */

 #ifdef PARALLEL_MARK
 # define INCR_MARKS(hhdr) \
 	AO_store(&(hhdr -> hb_n_marks), AO_load(&(hhdr -> hb_n_marks))+1);
 #else
 # define INCR_MARKS(hhdr) ++(hhdr -> hb_n_marks)
 #endif

 #ifdef ENABLE_TRACE
 # define TRACE(source, cmd) \
 	if (GC_trace_addr != 0 && (ptr_t)(source) == GC_trace_addr) cmd
 # define TRACE_TARGET(target, cmd) \
 	if (GC_trace_addr != 0 && (target) == *(ptr_t *)GC_trace_addr) cmd
 #else
 # define TRACE(source, cmd)
 # define TRACE_TARGET(source, cmd)
 #endif
 /* If the mark bit corresponding to current is not set, set it, and 	*/
 /* push the contents of the object on the mark stack.  Current points	*/
 /* to the bginning of the object.  We rely on the fact that the 	*/
 /* preceding header calculation will succeed for a pointer past the 	*/
 /* forst page of an object, only if it is in fact a valid pointer	*/
 /* to the object.  Thus we can omit the otherwise necessary tests	*/
 /* here.  Note in particular tha the "displ" value is the displacement	*/
 /* from the beggining of the heap block, which may itself be in the	*/
 /* interior of a large object.						*/
 #ifdef MARK_BIT_PER_GRANULE
 # define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
 		           source, exit_label, hhdr, do_offset_check) \
 { \
     size_t displ = HBLKDISPL(current); /* Displacement in block; in bytes. */\
     /* displ is always within range.  If current doesn't point to	*/ \
     /* first block, then we are in the all_interior_pointers case, and	*/ \
     /* it is safe to use any displacement value.			*/ \
     size_t gran_displ = BYTES_TO_GRANULES(displ); \
     size_t gran_offset = hhdr -> hb_map[gran_displ];	\
     size_t byte_offset = displ & (GRANULE_BYTES - 1); \
     ptr_t base = current;  \
     /* The following always fails for large block references. */ \
     if (EXPECT((gran_offset | byte_offset) != 0, FALSE))  { \
 	if (hhdr -> hb_large_block) { \
 	  /* gran_offset is bogus.	*/ \
 	  size_t obj_displ; \
 	  base = (ptr_t)(hhdr -> hb_block); \
 	  obj_displ = (ptr_t)(current) - base;  \
 	  if (obj_displ != displ) { \
 	    GC_ASSERT(obj_displ < hhdr -> hb_sz); \
 	    /* Must be in all_interior_pointer case, not first block */ \
 	    /* already did validity check on cache miss.	     */ \
 	    ; \
 	  } else { \
 	    if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
 	      GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
 	      goto exit_label; \
 	    } \
 	  } \
 	  gran_displ = 0; \
 	  GC_ASSERT(hhdr -> hb_sz > HBLKSIZE || \
 		    hhdr -> hb_block == HBLKPTR(current)); \
 	  GC_ASSERT((ptr_t)(hhdr -> hb_block) <= (ptr_t) current); \
 	} else { \
 	  size_t obj_displ = GRANULES_TO_BYTES(gran_offset) \
 		      	     + byte_offset; \
 	  if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
 	    GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
 	    goto exit_label; \
 	  } \
 	  gran_displ -= gran_offset; \
 	  base -= obj_displ; \
 	} \
     } \
     GC_ASSERT(hhdr == GC_find_header(base)); \
     GC_ASSERT(gran_displ % BYTES_TO_GRANULES(hhdr -> hb_sz) == 0); \
     TRACE(source, GC_log_printf("GC:%d: passed validity tests\n",GC_gc_no)); \
     SET_MARK_BIT_EXIT_IF_SET(hhdr, gran_displ, exit_label); \
     TRACE(source, GC_log_printf("GC:%d: previously unmarked\n",GC_gc_no)); \
     TRACE_TARGET(base, \
 	GC_log_printf("GC:%d: marking %p from %p instead\n", GC_gc_no, \
 		      base, source)); \
     INCR_MARKS(hhdr); \
     GC_STORE_BACK_PTR((ptr_t)source, base); \
     PUSH_OBJ(base, hhdr, mark_stack_top, mark_stack_limit); \
 }
 #endif /* MARK_BIT_PER_GRANULE */

 #ifdef MARK_BIT_PER_OBJ
 # define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
 		           source, exit_label, hhdr, do_offset_check) \
 { \
     size_t displ = HBLKDISPL(current); /* Displacement in block; in bytes. */\
     unsigned32 low_prod, high_prod, offset_fraction; \
     unsigned32 inv_sz = hhdr -> hb_inv_sz; \
     ptr_t base = current;  \
     LONG_MULT(high_prod, low_prod, displ, inv_sz); \
     /* product is > and within sz_in_bytes of displ * sz_in_bytes * 2**32 */ \
     if (EXPECT(low_prod >> 16 != 0, FALSE))  { \
 	    FIXME: fails if offset is a multiple of HBLKSIZE which becomes 0 \
 	if (inv_sz == LARGE_INV_SZ) { \
 	  size_t obj_displ; \
 	  base = (ptr_t)(hhdr -> hb_block); \
 	  obj_displ = (ptr_t)(current) - base;  \
 	  if (obj_displ != displ) { \
 	    GC_ASSERT(obj_displ < hhdr -> hb_sz); \
 	    /* Must be in all_interior_pointer case, not first block */ \
 	    /* already did validity check on cache miss.	     */ \
 	    ; \
 	  } else { \
 	    if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
 	      GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
 	      goto exit_label; \
 	    } \
 	  } \
 	  GC_ASSERT(hhdr -> hb_sz > HBLKSIZE || \
 		    hhdr -> hb_block == HBLKPTR(current)); \
 	  GC_ASSERT((ptr_t)(hhdr -> hb_block) < (ptr_t) current); \
 	} else { \
 	  /* Accurate enough if HBLKSIZE <= 2**15.	*/ \
 	  GC_ASSERT(HBLKSIZE <= (1 << 15)); \
 	  size_t obj_displ = (((low_prod >> 16) + 1) * (hhdr -> hb_sz)) >> 16; \
 	  if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
 	    GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
 	    goto exit_label; \
 	  } \
 	  base -= obj_displ; \
 	} \
     } \
     /* May get here for pointer to start of block not at	*/ \
     /* beginning of object.  If so, it's valid, and we're fine. */ \
     GC_ASSERT(high_prod >= 0 && high_prod <= HBLK_OBJS(hhdr -> hb_sz)); \
     TRACE(source, GC_log_printf("GC:%d: passed validity tests\n",GC_gc_no)); \
     SET_MARK_BIT_EXIT_IF_SET(hhdr, high_prod, exit_label); \
     TRACE(source, GC_log_printf("GC:%d: previously unmarked\n",GC_gc_no)); \
     TRACE_TARGET(base, \
 	GC_log_printf("GC:%d: marking %p from %p instead\n", GC_gc_no, \
 		      base, source)); \
     INCR_MARKS(hhdr); \
     GC_STORE_BACK_PTR((ptr_t)source, base); \
     PUSH_OBJ(base, hhdr, mark_stack_top, mark_stack_limit); \
 }
 #endif /* MARK_BIT_PER_OBJ */

 #if defined(PRINT_BLACK_LIST) || defined(KEEP_BACK_PTRS)
 #   define PUSH_ONE_CHECKED_STACK(p, source) \
 	GC_mark_and_push_stack(p, (ptr_t)(source))
 #else
 #   define PUSH_ONE_CHECKED_STACK(p, source) \
 	GC_mark_and_push_stack(p)
 #endif

 /*
  * Push a single value onto mark stack. Mark from the object pointed to by p.
  * Invoke FIXUP_POINTER(p) before any further processing.
  * P is considered valid even if it is an interior pointer.
  * Previously marked objects are not pushed.  Hence we make progress even
  * if the mark stack overflows.
  */

 # if NEED_FIXUP_POINTER
     /* Try both the raw version and the fixed up one.	*/
 #   define GC_PUSH_ONE_STACK(p, source) \
       if ((p) >= (ptr_t)GC_least_plausible_heap_addr 	\
 	 && (p) < (ptr_t)GC_greatest_plausible_heap_addr) {	\
 	 PUSH_ONE_CHECKED_STACK(p, source);	\
       } \
       FIXUP_POINTER(p); \
       if ((p) >= (ptr_t)GC_least_plausible_heap_addr 	\
 	 && (p) < (ptr_t)GC_greatest_plausible_heap_addr) {	\
 	 PUSH_ONE_CHECKED_STACK(p, source);	\
       }
 # else /* !NEED_FIXUP_POINTER */
 #   define GC_PUSH_ONE_STACK(p, source) \
       if ((ptr_t)(p) >= (ptr_t)GC_least_plausible_heap_addr 	\
 	 && (ptr_t)(p) < (ptr_t)GC_greatest_plausible_heap_addr) {	\
 	 PUSH_ONE_CHECKED_STACK(p, source);	\
       }
 # endif


 /*
  * As above, but interior pointer recognition as for
  * normal heap pointers.
  */
 # define GC_PUSH_ONE_HEAP(p,source) \
     FIXUP_POINTER(p); \
     if ((p) >= (ptr_t)GC_least_plausible_heap_addr 	\
 	 && (p) < (ptr_t)GC_greatest_plausible_heap_addr) {	\
 	    GC_mark_stack_top = GC_mark_and_push( \
 			    (void *)(p), GC_mark_stack_top, \
 			    GC_mark_stack_limit, (void * *)(source)); \
     }

 /* Mark starting at mark stack entry top (incl.) down to	*/
 /* mark stack entry bottom (incl.).  Stop after performing	*/
 /* about one page worth of work.  Return the new mark stack	*/
 /* top entry.							*/
 mse * GC_mark_from(mse * top, mse * bottom, mse *limit);

 #define MARK_FROM_MARK_STACK() \
 	GC_mark_stack_top = GC_mark_from(GC_mark_stack_top, \
 					 GC_mark_stack, \
 					 GC_mark_stack + GC_mark_stack_size);

 /*
  * Mark from one finalizable object using the specified
  * mark proc. May not mark the object pointed to by
  * real_ptr. That is the job of the caller, if appropriate.
  * Note that this is called with the mutator running, but
  * with us holding the allocation lock.  This is safe only if the
  * mutator needs tha allocation lock to reveal hidden pointers.
  * FIXME: Why do we need the GC_mark_state test below?
  */
 # define GC_MARK_FO(real_ptr, mark_proc) \
 { \
     (*(mark_proc))(real_ptr); \
     while (!GC_mark_stack_empty()) MARK_FROM_MARK_STACK(); \
     if (GC_mark_state != MS_NONE) { \
         GC_set_mark_bit(real_ptr); \
         while (!GC_mark_some((ptr_t)0)) {} \
     } \
 }

 extern GC_bool GC_mark_stack_too_small;
 				/* We need a larger mark stack.  May be	*/
 				/* set by client supplied mark routines.*/

 typedef int mark_state_t;	/* Current state of marking, as follows:*/
 				/* Used to remember where we are during */
 				/* concurrent marking.			*/

 				/* We say something is dirty if it was	*/
 				/* written since the last time we	*/
 				/* retrieved dirty bits.  We say it's 	*/
 				/* grungy if it was marked dirty in the	*/
 				/* last set of bits we retrieved.	*/

 				/* Invariant I: all roots and marked	*/
 				/* objects p are either dirty, or point */
 				/* to objects q that are either marked 	*/
 				/* or a pointer to q appears in a range	*/
 				/* on the mark stack.			*/

 # define MS_NONE 0		/* No marking in progress. I holds.	*/
 				/* Mark stack is empty.			*/

 # define MS_PUSH_RESCUERS 1	/* Rescuing objects are currently 	*/
 				/* being pushed.  I holds, except	*/
 				/* that grungy roots may point to 	*/
 				/* unmarked objects, as may marked	*/
 				/* grungy objects above scan_ptr.	*/

 # define MS_PUSH_UNCOLLECTABLE 2
 				/* I holds, except that marked 		*/
 				/* uncollectable objects above scan_ptr */
 				/* may point to unmarked objects.	*/
 				/* Roots may point to unmarked objects	*/

 # define MS_ROOTS_PUSHED 3	/* I holds, mark stack may be nonempty  */

 # define MS_PARTIALLY_INVALID 4	/* I may not hold, e.g. because of M.S. */
 				/* overflow.  However marked heap	*/
 				/* objects below scan_ptr point to	*/
 				/* marked or stacked objects.		*/

 # define MS_INVALID 5		/* I may not hold.			*/

 extern mark_state_t GC_mark_state;

 #endif  /* GC_PMARK_H */
	/*
	* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
	* Copyright (c) 2001 by Hewlett-Packard Company. All rights reserved.
	*
	* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
	* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
	*
	* Permission is hereby granted to use or copy this program
	* for any purpose, provided the above notices are retained on all copies.
	* Permission to modify the code and to distribute modified code is granted,
	* provided the above notices are retained, and a notice that the code was
	* modified is included with the above copyright notice.
	*
	*/

	/* Private declarations of GC marker data structures and macros */

	/*
	* Declarations of mark stack. Needed by marker and client supplied mark
	* routines. Transitively include gc_priv.h.
	* (Note that gc_priv.h should not be included before this, since this
	* includes dbg_mlc.h, which wants to include gc_priv.h AFTER defining
	* I_HIDE_POINTERS.)
	*/
	#ifndef GC_PMARK_H
	# define GC_PMARK_H

	# if defined(KEEP_BACK_PTRS) \|\| defined(PRINT_BLACK_LIST)
	# include "dbg_mlc.h"
	# endif
	# ifndef GC_MARK_H
	# include "../gc_mark.h"
	# endif
	# ifndef GC_PRIVATE_H
	# include "gc_priv.h"
	# endif

	/* The real declarations of the following is in gc_priv.h, so that */
	/* we can avoid scanning the following table. */
	/*
	extern mark_proc GC_mark_procs[MAX_MARK_PROCS];
	*/

	/*
	* Mark descriptor stuff that should remain private for now, mostly
	* because it's hard to export WORDSZ without including gcconfig.h.
	*/
	# define BITMAP_BITS (WORDSZ - GC_DS_TAG_BITS)
	# define PROC(descr) \
	(GC_mark_procs[((descr) >> GC_DS_TAG_BITS) & (GC_MAX_MARK_PROCS-1)])
	# define ENV(descr) \
	((descr) >> (GC_DS_TAG_BITS + GC_LOG_MAX_MARK_PROCS))
	# define MAX_ENV \
	(((word)1 << (WORDSZ - GC_DS_TAG_BITS - GC_LOG_MAX_MARK_PROCS)) - 1)


	extern unsigned GC_n_mark_procs;

	/* Number of mark stack entries to discard on overflow. */
	#define GC_MARK_STACK_DISCARDS (INITIAL_MARK_STACK_SIZE/8)

	typedef struct GC_ms_entry {
	ptr_t mse_start; /* First word of object */
	GC_word mse_descr; /* Descriptor; low order two bits are tags, */
	/* identifying the upper 30 bits as one of the */
	/* following: */
	} mse;

	extern size_t GC_mark_stack_size;

	extern mse * GC_mark_stack_limit;

	#ifdef PARALLEL_MARK
	extern mse * volatile GC_mark_stack_top;
	#else
	extern mse * GC_mark_stack_top;
	#endif

	extern mse * GC_mark_stack;

	#ifdef PARALLEL_MARK
	/*
	* Allow multiple threads to participate in the marking process.
	* This works roughly as follows:
	* The main mark stack never shrinks, but it can grow.
	*
	* The initiating threads holds the GC lock, and sets GC_help_wanted.
	*
	* Other threads:
	* 1) update helper_count (while holding mark_lock.)
	* 2) allocate a local mark stack
	* repeatedly:
	* 3) Steal a global mark stack entry by atomically replacing
	* its descriptor with 0.
	* 4) Copy it to the local stack.
	* 5) Mark on the local stack until it is empty, or
	* it may be profitable to copy it back.
	* 6) If necessary, copy local stack to global one,
	* holding mark lock.
	* 7) Stop when the global mark stack is empty.
	* 8) decrement helper_count (holding mark_lock).
	*
	* This is an experiment to see if we can do something along the lines
	* of the University of Tokyo SGC in a less intrusive, though probably
	* also less performant, way.
	*/
	void GC_do_parallel_mark();
	/* inititate parallel marking. */

	extern GC_bool GC_help_wanted; /* Protected by mark lock */
	extern unsigned GC_helper_count; /* Number of running helpers. */
	/* Protected by mark lock */
	extern unsigned GC_active_count; /* Number of active helpers. */
	/* Protected by mark lock */
	/* May increase and decrease */
	/* within each mark cycle. But */
	/* once it returns to 0, it */
	/* stays zero for the cycle. */
	/* GC_mark_stack_top is also protected by mark lock. */
	/*
	* GC_notify_all_marker() is used when GC_help_wanted is first set,
	* when the last helper becomes inactive,
	* when something is added to the global mark stack, and just after
	* GC_mark_no is incremented.
	* This could be split into multiple CVs (and probably should be to
	* scale to really large numbers of processors.)
	*/
	#endif /* PARALLEL_MARK */

	/* Return a pointer to within 1st page of object. */
	/* Set new_hdr_p to corr. hdr. /
	ptr_t GC_find_start(ptr_t current, hdr hhdr, hdr *new_hdr_p);

	mse * GC_signal_mark_stack_overflow(mse *msp);

	/* Push the object obj with corresponding heap block header hhdr onto */
	/* the mark stack. */
	# define PUSH_OBJ(obj, hhdr, mark_stack_top, mark_stack_limit) \
	{ \
	register word _descr = (hhdr) -> hb_descr; \
	\
	if (_descr != 0) { \
	mark_stack_top++; \
	if (mark_stack_top >= mark_stack_limit) { \
	mark_stack_top = GC_signal_mark_stack_overflow(mark_stack_top); \
	} \
	mark_stack_top -> mse_start = (obj); \
	mark_stack_top -> mse_descr = _descr; \
	} \
	}

	/* Push the contents of current onto the mark stack if it is a valid */
	/* ptr to a currently unmarked object. Mark it. */
	/* If we assumed a standard-conforming compiler, we could probably */
	/* generate the exit_label transparently. */
	# define PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, \
	source, exit_label) \
	{ \
	hdr * my_hhdr; \
	\
	HC_GET_HDR(current, my_hhdr, source, exit_label); \
	PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
	source, exit_label, my_hhdr, TRUE); \
	exit_label: ; \
	}

	/* Set mark bit, exit if it was already set. */

	# ifdef USE_MARK_BITS
	# ifdef PARALLEL_MARK
	/* The following may fail to exit even if the bit was already set. */
	/* For our uses, that's benign: */
	# define OR_WORD_EXIT_IF_SET(addr, bits, exit_label) \
	{ \
	if (!(*(addr) & (mask))) { \
	AO_or((AO_t *)(addr), (mask); \
	} else { \
	goto label; \
	} \
	}
	# else
	# define OR_WORD_EXIT_IF_SET(addr, bits, exit_label) \
	{ \
	word old = *(addr); \
	word my_bits = (bits); \
	if (old & my_bits) goto exit_label; \
	*(addr) = (old \| my_bits); \
	}
	# endif /* !PARALLEL_MARK */
	# define SET_MARK_BIT_EXIT_IF_SET(hhdr,bit_no,exit_label) \
	{ \
	word * mark_word_addr = hhdr -> hb_marks + divWORDSZ(bit_no); \
	\
	OR_WORD_EXIT_IF_SET(mark_word_addr, (word)1 << modWORDSZ(bit_no), \
	exit_label); \
	}
	# endif


	#ifdef USE_MARK_BYTES
	# if defined(I386) && defined(__GNUC__)
	# define LONG_MULT(hprod, lprod, x, y) { \
	asm("mull %2" : "=a"(lprod), "=d"(hprod) : "g"(y), "0"(x)); \
	}
	# else /* No in-line X86 assembly code */
	# define LONG_MULT(hprod, lprod, x, y) { \
	unsigned long long prod = (unsigned long long)x \
	* (unsigned long long)y; \
	hprod = prod >> 32; \
	lprod = (unsigned32)prod; \
	}
	# endif

	/* There is a race here, and we may set */
	/* the bit twice in the concurrent case. This can result in the */
	/* object being pushed twice. But that's only a performance issue. */
	# define SET_MARK_BIT_EXIT_IF_SET(hhdr,bit_no,exit_label) \
	{ \
	char * mark_byte_addr = (char *)hhdr -> hb_marks + (bit_no); \
	char mark_byte = *mark_byte_addr; \
	\
	if (mark_byte) goto exit_label; \
	*mark_byte_addr = 1; \
	}
	#endif /* USE_MARK_BYTES */

	#ifdef PARALLEL_MARK
	# define INCR_MARKS(hhdr) \
	AO_store(&(hhdr -> hb_n_marks), AO_load(&(hhdr -> hb_n_marks))+1);
	#else
	# define INCR_MARKS(hhdr) ++(hhdr -> hb_n_marks)
	#endif

	#ifdef ENABLE_TRACE
	# define TRACE(source, cmd) \
	if (GC_trace_addr != 0 && (ptr_t)(source) == GC_trace_addr) cmd
	# define TRACE_TARGET(target, cmd) \
	if (GC_trace_addr != 0 && (target) == (ptr_t )GC_trace_addr) cmd
	#else
	# define TRACE(source, cmd)
	# define TRACE_TARGET(source, cmd)
	#endif
	/* If the mark bit corresponding to current is not set, set it, and */
	/* push the contents of the object on the mark stack. Current points */
	/* to the bginning of the object. We rely on the fact that the */
	/* preceding header calculation will succeed for a pointer past the */
	/* forst page of an object, only if it is in fact a valid pointer */
	/* to the object. Thus we can omit the otherwise necessary tests */
	/* here. Note in particular tha the "displ" value is the displacement */
	/* from the beggining of the heap block, which may itself be in the */
	/* interior of a large object. */
	#ifdef MARK_BIT_PER_GRANULE
	# define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
	source, exit_label, hhdr, do_offset_check) \
	{ \
	size_t displ = HBLKDISPL(current); /* Displacement in block; in bytes. */\
	/* displ is always within range. If current doesn't point to */ \
	/* first block, then we are in the all_interior_pointers case, and */ \
	/* it is safe to use any displacement value. */ \
	size_t gran_displ = BYTES_TO_GRANULES(displ); \
	size_t gran_offset = hhdr -> hb_map[gran_displ]; \
	size_t byte_offset = displ & (GRANULE_BYTES - 1); \
	ptr_t base = current; \
	/* The following always fails for large block references. */ \
	if (EXPECT((gran_offset \| byte_offset) != 0, FALSE)) { \
	if (hhdr -> hb_large_block) { \
	/* gran_offset is bogus. */ \
	size_t obj_displ; \
	base = (ptr_t)(hhdr -> hb_block); \
	obj_displ = (ptr_t)(current) - base; \
	if (obj_displ != displ) { \
	GC_ASSERT(obj_displ < hhdr -> hb_sz); \
	/* Must be in all_interior_pointer case, not first block */ \
	/* already did validity check on cache miss. */ \
	; \
	} else { \
	if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
	GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
	goto exit_label; \
	} \
	} \
	gran_displ = 0; \
	GC_ASSERT(hhdr -> hb_sz > HBLKSIZE \|\| \
	hhdr -> hb_block == HBLKPTR(current)); \
	GC_ASSERT((ptr_t)(hhdr -> hb_block) <= (ptr_t) current); \
	} else { \
	size_t obj_displ = GRANULES_TO_BYTES(gran_offset) \
	+ byte_offset; \
	if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
	GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
	goto exit_label; \
	} \
	gran_displ -= gran_offset; \
	base -= obj_displ; \
	} \
	} \
	GC_ASSERT(hhdr == GC_find_header(base)); \
	GC_ASSERT(gran_displ % BYTES_TO_GRANULES(hhdr -> hb_sz) == 0); \
	TRACE(source, GC_log_printf("GC:%d: passed validity tests\n",GC_gc_no)); \
	SET_MARK_BIT_EXIT_IF_SET(hhdr, gran_displ, exit_label); \
	TRACE(source, GC_log_printf("GC:%d: previously unmarked\n",GC_gc_no)); \
	TRACE_TARGET(base, \
	GC_log_printf("GC:%d: marking %p from %p instead\n", GC_gc_no, \
	base, source)); \
	INCR_MARKS(hhdr); \
	GC_STORE_BACK_PTR((ptr_t)source, base); \
	PUSH_OBJ(base, hhdr, mark_stack_top, mark_stack_limit); \
	}
	#endif /* MARK_BIT_PER_GRANULE */

	#ifdef MARK_BIT_PER_OBJ
	# define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
	source, exit_label, hhdr, do_offset_check) \
	{ \
	size_t displ = HBLKDISPL(current); /* Displacement in block; in bytes. */\
	unsigned32 low_prod, high_prod, offset_fraction; \
	unsigned32 inv_sz = hhdr -> hb_inv_sz; \
	ptr_t base = current; \
	LONG_MULT(high_prod, low_prod, displ, inv_sz); \
	/* product is > and within sz_in_bytes of displ * sz_in_bytes * 2*32 / \
	if (EXPECT(low_prod >> 16 != 0, FALSE)) { \
	FIXME: fails if offset is a multiple of HBLKSIZE which becomes 0 \
	if (inv_sz == LARGE_INV_SZ) { \
	size_t obj_displ; \
	base = (ptr_t)(hhdr -> hb_block); \
	obj_displ = (ptr_t)(current) - base; \
	if (obj_displ != displ) { \
	GC_ASSERT(obj_displ < hhdr -> hb_sz); \
	/* Must be in all_interior_pointer case, not first block */ \
	/* already did validity check on cache miss. */ \
	; \
	} else { \
	if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
	GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
	goto exit_label; \
	} \
	} \
	GC_ASSERT(hhdr -> hb_sz > HBLKSIZE \|\| \
	hhdr -> hb_block == HBLKPTR(current)); \
	GC_ASSERT((ptr_t)(hhdr -> hb_block) < (ptr_t) current); \
	} else { \
	/* Accurate enough if HBLKSIZE <= 2*15. / \
	GC_ASSERT(HBLKSIZE <= (1 << 15)); \
	size_t obj_displ = (((low_prod >> 16) + 1) * (hhdr -> hb_sz)) >> 16; \
	if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
	GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
	goto exit_label; \
	} \
	base -= obj_displ; \
	} \
	} \
	/* May get here for pointer to start of block not at */ \
	/* beginning of object. If so, it's valid, and we're fine. */ \
	GC_ASSERT(high_prod >= 0 && high_prod <= HBLK_OBJS(hhdr -> hb_sz)); \
	TRACE(source, GC_log_printf("GC:%d: passed validity tests\n",GC_gc_no)); \
	SET_MARK_BIT_EXIT_IF_SET(hhdr, high_prod, exit_label); \
	TRACE(source, GC_log_printf("GC:%d: previously unmarked\n",GC_gc_no)); \
	TRACE_TARGET(base, \
	GC_log_printf("GC:%d: marking %p from %p instead\n", GC_gc_no, \
	base, source)); \
	INCR_MARKS(hhdr); \
	GC_STORE_BACK_PTR((ptr_t)source, base); \
	PUSH_OBJ(base, hhdr, mark_stack_top, mark_stack_limit); \
	}
	#endif /* MARK_BIT_PER_OBJ */

	#if defined(PRINT_BLACK_LIST) \|\| defined(KEEP_BACK_PTRS)
	# define PUSH_ONE_CHECKED_STACK(p, source) \
	GC_mark_and_push_stack(p, (ptr_t)(source))
	#else
	# define PUSH_ONE_CHECKED_STACK(p, source) \
	GC_mark_and_push_stack(p)
	#endif

	/*
	* Push a single value onto mark stack. Mark from the object pointed to by p.
	* Invoke FIXUP_POINTER(p) before any further processing.
	* P is considered valid even if it is an interior pointer.
	* Previously marked objects are not pushed. Hence we make progress even
	* if the mark stack overflows.
	*/

	# if NEED_FIXUP_POINTER
	/* Try both the raw version and the fixed up one. */
	# define GC_PUSH_ONE_STACK(p, source) \
	if ((p) >= (ptr_t)GC_least_plausible_heap_addr \
	&& (p) < (ptr_t)GC_greatest_plausible_heap_addr) { \
	PUSH_ONE_CHECKED_STACK(p, source); \
	} \
	FIXUP_POINTER(p); \
	if ((p) >= (ptr_t)GC_least_plausible_heap_addr \
	&& (p) < (ptr_t)GC_greatest_plausible_heap_addr) { \
	PUSH_ONE_CHECKED_STACK(p, source); \
	}
	# else /* !NEED_FIXUP_POINTER */
	# define GC_PUSH_ONE_STACK(p, source) \
	if ((ptr_t)(p) >= (ptr_t)GC_least_plausible_heap_addr \
	&& (ptr_t)(p) < (ptr_t)GC_greatest_plausible_heap_addr) { \
	PUSH_ONE_CHECKED_STACK(p, source); \
	}
	# endif


	/*
	* As above, but interior pointer recognition as for
	* normal heap pointers.
	*/
	# define GC_PUSH_ONE_HEAP(p,source) \
	FIXUP_POINTER(p); \
	if ((p) >= (ptr_t)GC_least_plausible_heap_addr \
	&& (p) < (ptr_t)GC_greatest_plausible_heap_addr) { \
	GC_mark_stack_top = GC_mark_and_push( \
	(void *)(p), GC_mark_stack_top, \
	GC_mark_stack_limit, (void * *)(source)); \
	}

	/* Mark starting at mark stack entry top (incl.) down to */
	/* mark stack entry bottom (incl.). Stop after performing */
	/* about one page worth of work. Return the new mark stack */
	/* top entry. */
	mse * GC_mark_from(mse * top, mse * bottom, mse *limit);

	#define MARK_FROM_MARK_STACK() \
	GC_mark_stack_top = GC_mark_from(GC_mark_stack_top, \
	GC_mark_stack, \
	GC_mark_stack + GC_mark_stack_size);

	/*
	* Mark from one finalizable object using the specified
	* mark proc. May not mark the object pointed to by
	* real_ptr. That is the job of the caller, if appropriate.
	* Note that this is called with the mutator running, but
	* with us holding the allocation lock. This is safe only if the
	* mutator needs tha allocation lock to reveal hidden pointers.
	* FIXME: Why do we need the GC_mark_state test below?
	*/
	# define GC_MARK_FO(real_ptr, mark_proc) \
	{ \
	(*(mark_proc))(real_ptr); \
	while (!GC_mark_stack_empty()) MARK_FROM_MARK_STACK(); \
	if (GC_mark_state != MS_NONE) { \
	GC_set_mark_bit(real_ptr); \
	while (!GC_mark_some((ptr_t)0)) {} \
	} \
	}

	extern GC_bool GC_mark_stack_too_small;
	/* We need a larger mark stack. May be */
	/* set by client supplied mark routines.*/

	typedef int mark_state_t; /* Current state of marking, as follows:*/
	/* Used to remember where we are during */
	/* concurrent marking. */

	/* We say something is dirty if it was */
	/* written since the last time we */
	/* retrieved dirty bits. We say it's */
	/* grungy if it was marked dirty in the */
	/* last set of bits we retrieved. */

	/* Invariant I: all roots and marked */
	/* objects p are either dirty, or point */
	/* to objects q that are either marked */
	/* or a pointer to q appears in a range */
	/* on the mark stack. */

	# define MS_NONE 0 /* No marking in progress. I holds. */
	/* Mark stack is empty. */

	# define MS_PUSH_RESCUERS 1 /* Rescuing objects are currently */
	/* being pushed. I holds, except */
	/* that grungy roots may point to */
	/* unmarked objects, as may marked */
	/* grungy objects above scan_ptr. */

	# define MS_PUSH_UNCOLLECTABLE 2
	/* I holds, except that marked */
	/* uncollectable objects above scan_ptr */
	/* may point to unmarked objects. */
	/* Roots may point to unmarked objects */

	# define MS_ROOTS_PUSHED 3 /* I holds, mark stack may be nonempty */

	# define MS_PARTIALLY_INVALID 4 /* I may not hold, e.g. because of M.S. */
	/* overflow. However marked heap */
	/* objects below scan_ptr point to */
	/* marked or stacked objects. */

	# define MS_INVALID 5 /* I may not hold. */

	extern mark_state_t GC_mark_state;

	#endif /* GC_PMARK_H */