obtained gcc-4.6.4.tar.bz2 from upstream website;upstream

verified gcc-4.6.4.tar.bz2.sig;
imported gcc-4.6.4 source tree from verified upstream tarball.

downloading a git-generated archive based on the 'upstream' tag
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however, do note that line-endings of files in your working
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1 files changed, 1817 insertions, 0 deletions

diff --git a/boehm-gc/mark.c b/boehm-gc/mark.c
new file mode 100644
index 000000000..09dfe92af
--- /dev/null
+++ b/boehm-gc/mark.c
@@ -0,0 +1,1817 @@
+
+/*
+ * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
+ * Copyright (c) 1991-1995 by Xerox Corporation.  All rights reserved.
+ * Copyright (c) 2000 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.
+ *
+ */
+
+
+# include <stdio.h>
+# include "private/gc_pmark.h"
+
+#if defined(MSWIN32) && defined(__GNUC__)
+# include <excpt.h>
+#endif
+
+/* We put this here to minimize the risk of inlining. */
+/*VARARGS*/
+#ifdef __WATCOMC__
+  void GC_noop(void *p, ...) {}
+#else
+  void GC_noop() {}
+#endif
+
+/* Single argument version, robust against whole program analysis. */
+void GC_noop1(x)
+word x;
+{
+    static VOLATILE word sink;
+
+    sink = x;
+}
+
+/* mark_proc GC_mark_procs[MAX_MARK_PROCS] = {0} -- declared in gc_priv.h */
+
+word GC_n_mark_procs = GC_RESERVED_MARK_PROCS;
+
+/* Initialize GC_obj_kinds properly and standard free lists properly.  	*/
+/* This must be done statically since they may be accessed before 	*/
+/* GC_init is called.							*/
+/* It's done here, since we need to deal with mark descriptors.		*/
+struct obj_kind GC_obj_kinds[MAXOBJKINDS] = {
+/* PTRFREE */ { &GC_aobjfreelist[0], 0 /* filled in dynamically */,
+		0 | GC_DS_LENGTH, FALSE, FALSE },
+/* NORMAL  */ { &GC_objfreelist[0], 0,
+		0 | GC_DS_LENGTH,  /* Adjusted in GC_init_inner for EXTRA_BYTES */
+		TRUE /* add length to descr */, TRUE },
+/* UNCOLLECTABLE */
+	      { &GC_uobjfreelist[0], 0,
+		0 | GC_DS_LENGTH, TRUE /* add length to descr */, TRUE },
+# ifdef ATOMIC_UNCOLLECTABLE
+   /* AUNCOLLECTABLE */
+	      { &GC_auobjfreelist[0], 0,
+		0 | GC_DS_LENGTH, FALSE /* add length to descr */, FALSE },
+# endif
+# ifdef STUBBORN_ALLOC
+/*STUBBORN*/ { &GC_sobjfreelist[0], 0,
+		0 | GC_DS_LENGTH, TRUE /* add length to descr */, TRUE },
+# endif
+};
+
+# ifdef ATOMIC_UNCOLLECTABLE
+#   ifdef STUBBORN_ALLOC
+      int GC_n_kinds = 5;
+#   else
+      int GC_n_kinds = 4;
+#   endif
+# else
+#   ifdef STUBBORN_ALLOC
+      int GC_n_kinds = 4;
+#   else
+      int GC_n_kinds = 3;
+#   endif
+# endif
+
+
+# ifndef INITIAL_MARK_STACK_SIZE
+#   define INITIAL_MARK_STACK_SIZE (1*HBLKSIZE)
+		/* INITIAL_MARK_STACK_SIZE * sizeof(mse) should be a 	*/
+		/* multiple of HBLKSIZE.				*/
+		/* The incremental collector actually likes a larger	*/
+		/* size, since it want to push all marked dirty objs	*/
+		/* before marking anything new.  Currently we let it	*/
+		/* grow dynamically.					*/
+# endif
+
+/*
+ * Limits of stack for GC_mark routine.
+ * All ranges between GC_mark_stack(incl.) and GC_mark_stack_top(incl.) still
+ * need to be marked from.
+ */
+
+word GC_n_rescuing_pages;	/* Number of dirty pages we marked from */
+				/* excludes ptrfree pages, etc.		*/
+
+mse * GC_mark_stack;
+
+mse * GC_mark_stack_limit;
+
+word GC_mark_stack_size = 0;
+ 
+#ifdef PARALLEL_MARK
+  mse * VOLATILE GC_mark_stack_top;
+#else
+  mse * GC_mark_stack_top;
+#endif
+
+static struct hblk * scan_ptr;
+
+mark_state_t GC_mark_state = MS_NONE;
+
+GC_bool GC_mark_stack_too_small = FALSE;
+
+GC_bool GC_objects_are_marked = FALSE;	/* Are there collectable marked	*/
+					/* objects in the heap?		*/
+
+/* Is a collection in progress?  Note that this can return true in the	*/
+/* nonincremental case, if a collection has been abandoned and the	*/
+/* mark state is now MS_INVALID.					*/
+GC_bool GC_collection_in_progress()
+{
+    return(GC_mark_state != MS_NONE);
+}
+
+/* clear all mark bits in the header */
+void GC_clear_hdr_marks(hhdr)
+register hdr * hhdr;
+{
+#   ifdef USE_MARK_BYTES
+      BZERO(hhdr -> hb_marks, MARK_BITS_SZ);
+#   else
+      BZERO(hhdr -> hb_marks, MARK_BITS_SZ*sizeof(word));
+#   endif
+}
+
+/* Set all mark bits in the header.  Used for uncollectable blocks. */
+void GC_set_hdr_marks(hhdr)
+register hdr * hhdr;
+{
+    register int i;
+
+    for (i = 0; i < MARK_BITS_SZ; ++i) {
+#     ifdef USE_MARK_BYTES
+    	hhdr -> hb_marks[i] = 1;
+#     else
+    	hhdr -> hb_marks[i] = ONES;
+#     endif
+    }
+}
+
+/*
+ * Clear all mark bits associated with block h.
+ */
+/*ARGSUSED*/
+# if defined(__STDC__) || defined(__cplusplus)
+    static void clear_marks_for_block(struct hblk *h, word dummy)
+# else
+    static void clear_marks_for_block(h, dummy)
+    struct hblk *h;
+    word dummy;
+# endif
+{
+    register hdr * hhdr = HDR(h);
+    
+    if (IS_UNCOLLECTABLE(hhdr -> hb_obj_kind)) return;
+        /* Mark bit for these is cleared only once the object is 	*/
+        /* explicitly deallocated.  This either frees the block, or	*/
+        /* the bit is cleared once the object is on the free list.	*/
+    GC_clear_hdr_marks(hhdr);
+}
+
+/* Slow but general routines for setting/clearing/asking about mark bits */
+void GC_set_mark_bit(p)
+ptr_t p;
+{
+    register struct hblk *h = HBLKPTR(p);
+    register hdr * hhdr = HDR(h);
+    register int word_no = (word *)p - (word *)h;
+    
+    set_mark_bit_from_hdr(hhdr, word_no);
+}
+
+void GC_clear_mark_bit(p)
+ptr_t p;
+{
+    register struct hblk *h = HBLKPTR(p);
+    register hdr * hhdr = HDR(h);
+    register int word_no = (word *)p - (word *)h;
+    
+    clear_mark_bit_from_hdr(hhdr, word_no);
+}
+
+GC_bool GC_is_marked(p)
+ptr_t p;
+{
+    register struct hblk *h = HBLKPTR(p);
+    register hdr * hhdr = HDR(h);
+    register int word_no = (word *)p - (word *)h;
+    
+    return(mark_bit_from_hdr(hhdr, word_no));
+}
+
+
+/*
+ * Clear mark bits in all allocated heap blocks.  This invalidates
+ * the marker invariant, and sets GC_mark_state to reflect this.
+ * (This implicitly starts marking to reestablish the invariant.)
+ */
+void GC_clear_marks()
+{
+    GC_apply_to_all_blocks(clear_marks_for_block, (word)0);
+    GC_objects_are_marked = FALSE;
+    GC_mark_state = MS_INVALID;
+    scan_ptr = 0;
+#   ifdef GATHERSTATS
+	/* Counters reflect currently marked objects: reset here */
+        GC_composite_in_use = 0;
+        GC_atomic_in_use = 0;
+#   endif
+
+}
+
+/* Initiate a garbage collection.  Initiates a full collection if the	*/
+/* mark	state is invalid.						*/
+/*ARGSUSED*/
+void GC_initiate_gc()
+{
+    if (GC_dirty_maintained) GC_read_dirty();
+#   ifdef STUBBORN_ALLOC
+    	GC_read_changed();
+#   endif
+#   ifdef CHECKSUMS
+	{
+	    extern void GC_check_dirty();
+	    
+	    if (GC_dirty_maintained) GC_check_dirty();
+	}
+#   endif
+    GC_n_rescuing_pages = 0;
+    if (GC_mark_state == MS_NONE) {
+        GC_mark_state = MS_PUSH_RESCUERS;
+    } else if (GC_mark_state != MS_INVALID) {
+    	ABORT("unexpected state");
+    } /* else this is really a full collection, and mark	*/
+      /* bits are invalid.					*/
+    scan_ptr = 0;
+}
+
+
+static void alloc_mark_stack();
+
+/* Perform a small amount of marking.			*/
+/* We try to touch roughly a page of memory.		*/
+/* Return TRUE if we just finished a mark phase.	*/
+/* Cold_gc_frame is an address inside a GC frame that	*/
+/* remains valid until all marking is complete.		*/
+/* A zero value indicates that it's OK to miss some	*/
+/* register values.					*/
+/* We hold the allocation lock.  In the case of 	*/
+/* incremental collection, the world may not be stopped.*/
+#ifdef MSWIN32
+  /* For win32, this is called after we establish a structured	*/
+  /* exception handler, in case Windows unmaps one of our root	*/
+  /* segments.  See below.  In either case, we acquire the 	*/
+  /* allocator lock long before we get here.			*/
+  GC_bool GC_mark_some_inner(cold_gc_frame)
+  ptr_t cold_gc_frame;
+#else
+  GC_bool GC_mark_some(cold_gc_frame)
+  ptr_t cold_gc_frame;
+#endif
+{
+    switch(GC_mark_state) {
+    	case MS_NONE:
+    	    return(FALSE);
+    	    
+    	case MS_PUSH_RESCUERS:
+    	    if (GC_mark_stack_top
+    	        >= GC_mark_stack_limit - INITIAL_MARK_STACK_SIZE/2) {
+		/* Go ahead and mark, even though that might cause us to */
+		/* see more marked dirty objects later on.  Avoid this	 */
+		/* in the future.					 */
+		GC_mark_stack_too_small = TRUE;
+    	        MARK_FROM_MARK_STACK();
+    	        return(FALSE);
+    	    } else {
+    	        scan_ptr = GC_push_next_marked_dirty(scan_ptr);
+    	        if (scan_ptr == 0) {
+#		    ifdef CONDPRINT
+		      if (GC_print_stats) {
+			GC_printf1("Marked from %lu dirty pages\n",
+				   (unsigned long)GC_n_rescuing_pages);
+		      }
+#		    endif
+    	    	    GC_push_roots(FALSE, cold_gc_frame);
+    	    	    GC_objects_are_marked = TRUE;
+    	    	    if (GC_mark_state != MS_INVALID) {
+    	    	        GC_mark_state = MS_ROOTS_PUSHED;
+    	    	    }
+    	    	}
+    	    }
+    	    return(FALSE);
+    	
+    	case MS_PUSH_UNCOLLECTABLE:
+    	    if (GC_mark_stack_top
+    	        >= GC_mark_stack + GC_mark_stack_size/4) {
+#		ifdef PARALLEL_MARK
+		  /* Avoid this, since we don't parallelize the marker	*/
+		  /* here.						*/
+		  if (GC_parallel) GC_mark_stack_too_small = TRUE;
+#		endif
+    	        MARK_FROM_MARK_STACK();
+    	        return(FALSE);
+    	    } else {
+    	        scan_ptr = GC_push_next_marked_uncollectable(scan_ptr);
+    	        if (scan_ptr == 0) {
+    	    	    GC_push_roots(TRUE, cold_gc_frame);
+    	    	    GC_objects_are_marked = TRUE;
+    	    	    if (GC_mark_state != MS_INVALID) {
+    	    	        GC_mark_state = MS_ROOTS_PUSHED;
+    	    	    }
+    	    	}
+    	    }
+    	    return(FALSE);
+    	
+    	case MS_ROOTS_PUSHED:
+#	    ifdef PARALLEL_MARK
+	      /* In the incremental GC case, this currently doesn't	*/
+	      /* quite do the right thing, since it runs to		*/
+	      /* completion.  On the other hand, starting a		*/
+	      /* parallel marker is expensive, so perhaps it is		*/
+	      /* the right thing?					*/
+	      /* Eventually, incremental marking should run		*/
+	      /* asynchronously in multiple threads, without grabbing	*/
+	      /* the allocation lock.					*/
+	        if (GC_parallel) {
+		  GC_do_parallel_mark();
+		  GC_ASSERT(GC_mark_stack_top < GC_first_nonempty);
+		  GC_mark_stack_top = GC_mark_stack - 1;
+    	          if (GC_mark_stack_too_small) {
+    	            alloc_mark_stack(2*GC_mark_stack_size);
+    	          }
+		  if (GC_mark_state == MS_ROOTS_PUSHED) {
+    	            GC_mark_state = MS_NONE;
+    	            return(TRUE);
+		  } else {
+		    return(FALSE);
+	          }
+		}
+#	    endif
+    	    if (GC_mark_stack_top >= GC_mark_stack) {
+    	        MARK_FROM_MARK_STACK();
+    	        return(FALSE);
+    	    } else {
+    	        GC_mark_state = MS_NONE;
+    	        if (GC_mark_stack_too_small) {
+    	            alloc_mark_stack(2*GC_mark_stack_size);
+    	        }
+    	        return(TRUE);
+    	    }
+    	    
+    	case MS_INVALID:
+    	case MS_PARTIALLY_INVALID:
+	    if (!GC_objects_are_marked) {
+		GC_mark_state = MS_PUSH_UNCOLLECTABLE;
+		return(FALSE);
+	    }
+    	    if (GC_mark_stack_top >= GC_mark_stack) {
+    	        MARK_FROM_MARK_STACK();
+    	        return(FALSE);
+    	    }
+    	    if (scan_ptr == 0 && GC_mark_state == MS_INVALID) {
+		/* About to start a heap scan for marked objects. */
+		/* Mark stack is empty.  OK to reallocate.	  */
+		if (GC_mark_stack_too_small) {
+    	            alloc_mark_stack(2*GC_mark_stack_size);
+		}
+		GC_mark_state = MS_PARTIALLY_INVALID;
+    	    }
+    	    scan_ptr = GC_push_next_marked(scan_ptr);
+    	    if (scan_ptr == 0 && GC_mark_state == MS_PARTIALLY_INVALID) {
+    	    	GC_push_roots(TRUE, cold_gc_frame);
+    	    	GC_objects_are_marked = TRUE;
+    	    	if (GC_mark_state != MS_INVALID) {
+    	    	    GC_mark_state = MS_ROOTS_PUSHED;
+    	    	}
+    	    }
+    	    return(FALSE);
+    	default:
+    	    ABORT("GC_mark_some: bad state");
+    	    return(FALSE);
+    }
+}
+
+
+#ifdef MSWIN32
+
+# ifdef __GNUC__
+
+    typedef struct {
+      EXCEPTION_REGISTRATION ex_reg;
+      void *alt_path;
+    } ext_ex_regn;
+
+
+    static EXCEPTION_DISPOSITION mark_ex_handler(
+        struct _EXCEPTION_RECORD *ex_rec, 
+        void *est_frame,
+        struct _CONTEXT *context,
+        void *disp_ctxt)
+    {
+        if (ex_rec->ExceptionCode == STATUS_ACCESS_VIOLATION) {
+          ext_ex_regn *xer = (ext_ex_regn *)est_frame;
+
+          /* Unwind from the inner function assuming the standard */
+          /* function prologue.                                   */
+          /* Assumes code has not been compiled with              */
+          /* -fomit-frame-pointer.                                */
+          context->Esp = context->Ebp;
+          context->Ebp = *((DWORD *)context->Esp);
+          context->Esp = context->Esp - 8;
+
+          /* Resume execution at the "real" handler within the    */
+          /* wrapper function.                                    */
+          context->Eip = (DWORD )(xer->alt_path);
+
+          return ExceptionContinueExecution;
+
+        } else {
+            return ExceptionContinueSearch;
+        }
+    }
+# endif /* __GNUC__ */
+
+
+  GC_bool GC_mark_some(cold_gc_frame)
+  ptr_t cold_gc_frame;
+  {
+      GC_bool ret_val;
+
+#   ifndef __GNUC__
+      /* Windows 98 appears to asynchronously create and remove  */
+      /* writable memory mappings, for reasons we haven't yet    */
+      /* understood.  Since we look for writable regions to      */
+      /* determine the root set, we may try to mark from an      */
+      /* address range that disappeared since we started the     */
+      /* collection.  Thus we have to recover from faults here.  */
+      /* This code does not appear to be necessary for Windows   */
+      /* 95/NT/2000. Note that this code should never generate   */
+      /* an incremental GC write fault.                          */
+
+      __try {
+
+#   else /* __GNUC__ */
+
+      /* Manually install an exception handler since GCC does    */
+      /* not yet support Structured Exception Handling (SEH) on  */
+      /* Win32.                                                  */
+
+      ext_ex_regn er;
+
+      er.alt_path = &&handle_ex;
+      er.ex_reg.handler = mark_ex_handler;
+      asm volatile ("movl %%fs:0, %0" : "=r" (er.ex_reg.prev));
+      asm volatile ("movl %0, %%fs:0" : : "r" (&er));
+
+#   endif /* __GNUC__ */
+
+          ret_val = GC_mark_some_inner(cold_gc_frame);
+
+#   ifndef __GNUC__
+
+      } __except (GetExceptionCode() == EXCEPTION_ACCESS_VIOLATION ?
+                EXCEPTION_EXECUTE_HANDLER : EXCEPTION_CONTINUE_SEARCH) {
+
+#   else /* __GNUC__ */
+
+          /* Prevent GCC from considering the following code unreachable */
+          /* and thus eliminating it.                                    */
+          if (er.alt_path != 0)
+              goto rm_handler;
+
+handle_ex:
+          /* Execution resumes from here on an access violation. */
+
+#   endif /* __GNUC__ */
+
+#         ifdef CONDPRINT
+            if (GC_print_stats) {
+	      GC_printf0("Caught ACCESS_VIOLATION in marker. "
+		         "Memory mapping disappeared.\n");
+            }
+#         endif /* CONDPRINT */
+
+          /* We have bad roots on the stack.  Discard mark stack.  */
+          /* Rescan from marked objects.  Redetermine roots.	 */
+          GC_invalidate_mark_state();	
+          scan_ptr = 0;
+
+          ret_val = FALSE;
+
+#   ifndef __GNUC__
+
+      }
+
+#   else /* __GNUC__ */
+
+rm_handler:
+      /* Uninstall the exception handler */
+      asm volatile ("mov %0, %%fs:0" : : "r" (er.ex_reg.prev));
+
+#   endif /* __GNUC__ */
+
+      return ret_val;
+  }
+#endif /* MSWIN32 */
+
+
+GC_bool GC_mark_stack_empty()
+{
+    return(GC_mark_stack_top < GC_mark_stack);
+}	
+
+#ifdef PROF_MARKER
+    word GC_prof_array[10];
+#   define PROF(n) GC_prof_array[n]++
+#else
+#   define PROF(n)
+#endif
+
+/* Given a pointer to someplace other than a small object page or the	*/
+/* first page of a large object, either:				*/
+/*	- return a pointer to somewhere in the first page of the large	*/
+/*	  object, if current points to a large object.			*/
+/*	  In this case *hhdr is replaced with a pointer to the header	*/
+/*	  for the large object.						*/
+/*	- just return current if it does not point to a large object.	*/
+/*ARGSUSED*/
+ptr_t GC_find_start(current, hhdr, new_hdr_p)
+register ptr_t current;
+register hdr *hhdr, **new_hdr_p;
+{
+    if (GC_all_interior_pointers) {
+	if (hhdr != 0) {
+	    register ptr_t orig = current;
+	    
+	    current = (ptr_t)HBLKPTR(current);
+	    do {
+	      current = current - HBLKSIZE*(word)hhdr;
+	      hhdr = HDR(current);
+	    } while(IS_FORWARDING_ADDR_OR_NIL(hhdr));
+	    /* current points to near the start of the large object */
+	    if (hhdr -> hb_flags & IGNORE_OFF_PAGE) return(orig);
+	    if ((word *)orig - (word *)current
+	         >= (ptrdiff_t)(hhdr->hb_sz)) {
+	        /* Pointer past the end of the block */
+	        return(orig);
+	    }
+	    *new_hdr_p = hhdr;
+	    return(current);
+	} else {
+	    return(current);
+        }
+    } else {
+        return(current);
+    }
+}
+
+void GC_invalidate_mark_state()
+{
+    GC_mark_state = MS_INVALID;
+    GC_mark_stack_top = GC_mark_stack-1;
+}
+
+mse * GC_signal_mark_stack_overflow(msp)
+mse * msp;
+{
+    GC_mark_state = MS_INVALID;
+    GC_mark_stack_too_small = TRUE;
+#   ifdef CONDPRINT
+      if (GC_print_stats) {
+	GC_printf1("Mark stack overflow; current size = %lu entries\n",
+	    	    GC_mark_stack_size);
+      }
+#   endif
+    return(msp - GC_MARK_STACK_DISCARDS);
+}
+
+/*
+ * Mark objects pointed to by the regions described by
+ * mark stack entries between GC_mark_stack and GC_mark_stack_top,
+ * inclusive.  Assumes the upper limit of a mark stack entry
+ * is never 0.  A mark stack entry never has size 0.
+ * We try to traverse on the order of a hblk of memory before we return.
+ * Caller is responsible for calling this until the mark stack is empty.
+ * Note that this is the most performance critical routine in the
+ * collector.  Hence it contains all sorts of ugly hacks to speed
+ * things up.  In particular, we avoid procedure calls on the common
+ * path, we take advantage of peculiarities of the mark descriptor
+ * encoding, we optionally maintain a cache for the block address to
+ * header mapping, we prefetch when an object is "grayed", etc. 
+ */
+mse * GC_mark_from(mark_stack_top, mark_stack, mark_stack_limit)
+mse * mark_stack_top;
+mse * mark_stack;
+mse * mark_stack_limit;
+{
+  int credit = HBLKSIZE;	/* Remaining credit for marking work	*/
+  register word * current_p;	/* Pointer to current candidate ptr.	*/
+  register word current;	/* Candidate pointer.			*/
+  register word * limit;	/* (Incl) limit of current candidate 	*/
+  				/* range				*/
+  register word descr;
+  register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
+  register ptr_t least_ha = GC_least_plausible_heap_addr;
+  DECLARE_HDR_CACHE;
+
+# define SPLIT_RANGE_WORDS 128  /* Must be power of 2.		*/
+
+  GC_objects_are_marked = TRUE;
+  INIT_HDR_CACHE;
+# ifdef OS2 /* Use untweaked version to circumvent compiler problem */
+  while (mark_stack_top >= mark_stack && credit >= 0) {
+# else
+  while ((((ptr_t)mark_stack_top - (ptr_t)mark_stack) | credit)
+  	>= 0) {
+# endif
+    current_p = mark_stack_top -> mse_start;
+    descr = mark_stack_top -> mse_descr;
+  retry:
+    /* current_p and descr describe the current object.		*/
+    /* *mark_stack_top is vacant.				*/
+    /* The following is 0 only for small objects described by a simple	*/
+    /* length descriptor.  For many applications this is the common	*/
+    /* case, so we try to detect it quickly.				*/
+    if (descr & ((~(WORDS_TO_BYTES(SPLIT_RANGE_WORDS) - 1)) | GC_DS_TAGS)) {
+      word tag = descr & GC_DS_TAGS;
+      
+      switch(tag) {
+        case GC_DS_LENGTH:
+          /* Large length.					        */
+          /* Process part of the range to avoid pushing too much on the	*/
+          /* stack.							*/
+	  GC_ASSERT(descr < (word)GC_greatest_plausible_heap_addr
+			    - (word)GC_least_plausible_heap_addr);
+#	  ifdef PARALLEL_MARK
+#	    define SHARE_BYTES 2048
+	    if (descr > SHARE_BYTES && GC_parallel
+		&& mark_stack_top < mark_stack_limit - 1) {
+	      int new_size = (descr/2) & ~(sizeof(word)-1);
+	      mark_stack_top -> mse_start = current_p;
+	      mark_stack_top -> mse_descr = new_size + sizeof(word);
+					/* makes sure we handle 	*/
+					/* misaligned pointers.		*/
+	      mark_stack_top++;
+	      current_p = (word *) ((char *)current_p + new_size);
+	      descr -= new_size;
+	      goto retry;
+	    }
+#	  endif /* PARALLEL_MARK */
+          mark_stack_top -> mse_start =
+         	limit = current_p + SPLIT_RANGE_WORDS-1;
+          mark_stack_top -> mse_descr =
+          		descr - WORDS_TO_BYTES(SPLIT_RANGE_WORDS-1);
+          /* Make sure that pointers overlapping the two ranges are	*/
+          /* considered. 						*/
+          limit = (word *)((char *)limit + sizeof(word) - ALIGNMENT);
+          break;
+        case GC_DS_BITMAP:
+          mark_stack_top--;
+          descr &= ~GC_DS_TAGS;
+          credit -= WORDS_TO_BYTES(WORDSZ/2); /* guess */
+          while (descr != 0) {
+            if ((signed_word)descr < 0) {
+              current = *current_p;
+	      FIXUP_POINTER(current);
+	      if ((ptr_t)current >= least_ha && (ptr_t)current < greatest_ha) {
+		PREFETCH((ptr_t)current);
+                HC_PUSH_CONTENTS((ptr_t)current, mark_stack_top,
+			      mark_stack_limit, current_p, exit1);
+	      }
+            }
+	    descr <<= 1;
+	    ++ current_p;
+          }
+          continue;
+        case GC_DS_PROC:
+          mark_stack_top--;
+          credit -= GC_PROC_BYTES;
+          mark_stack_top =
+              (*PROC(descr))
+              	    (current_p, mark_stack_top,
+              	    mark_stack_limit, ENV(descr));
+          continue;
+        case GC_DS_PER_OBJECT:
+	  if ((signed_word)descr >= 0) {
+	    /* Descriptor is in the object.	*/
+            descr = *(word *)((ptr_t)current_p + descr - GC_DS_PER_OBJECT);
+	  } else {
+	    /* Descriptor is in type descriptor pointed to by first	*/
+	    /* word in object.						*/
+	    ptr_t type_descr = *(ptr_t *)current_p;
+	    /* type_descr is either a valid pointer to the descriptor	*/
+	    /* structure, or this object was on a free list.  If it 	*/
+	    /* it was anything but the last object on the free list,	*/
+	    /* we will misinterpret the next object on the free list as */
+	    /* the type descriptor, and get a 0 GC descriptor, which	*/
+	    /* is ideal.  Unfortunately, we need to check for the last	*/
+	    /* object case explicitly.					*/
+	    if (0 == type_descr) {
+		/* Rarely executed.	*/
+		mark_stack_top--;
+		continue;
+	    }
+            descr = *(word *)(type_descr
+			      - (descr - (GC_DS_PER_OBJECT
+					  - GC_INDIR_PER_OBJ_BIAS)));
+	  }
+	  if (0 == descr) {
+	      /* Can happen either because we generated a 0 descriptor	*/
+	      /* or we saw a pointer to a free object.			*/
+	      mark_stack_top--;
+	      continue;
+	  }
+          goto retry;
+      }
+    } else /* Small object with length descriptor */ {
+      mark_stack_top--;
+      limit = (word *)(((ptr_t)current_p) + (word)descr);
+    }
+    /* The simple case in which we're scanning a range.	*/
+    GC_ASSERT(!((word)current_p & (ALIGNMENT-1)));
+    credit -= (ptr_t)limit - (ptr_t)current_p;
+    limit -= 1;
+    {
+#     define PREF_DIST 4
+
+#     ifndef SMALL_CONFIG
+        word deferred;
+
+	/* Try to prefetch the next pointer to be examined asap.	*/
+	/* Empirically, this also seems to help slightly without	*/
+	/* prefetches, at least on linux/X86.  Presumably this loop 	*/
+	/* ends up with less register pressure, and gcc thus ends up 	*/
+	/* generating slightly better code.  Overall gcc code quality	*/
+	/* for this loop is still not great.				*/
+	for(;;) {
+	  PREFETCH((ptr_t)limit - PREF_DIST*CACHE_LINE_SIZE);
+	  GC_ASSERT(limit >= current_p);
+	  deferred = *limit;
+	  FIXUP_POINTER(deferred);
+	  limit = (word *)((char *)limit - ALIGNMENT);
+	  if ((ptr_t)deferred >= least_ha && (ptr_t)deferred <  greatest_ha) {
+	    PREFETCH((ptr_t)deferred);
+	    break;
+	  }
+	  if (current_p > limit) goto next_object;
+	  /* Unroll once, so we don't do too many of the prefetches 	*/
+	  /* based on limit.						*/
+	  deferred = *limit;
+	  FIXUP_POINTER(deferred);
+	  limit = (word *)((char *)limit - ALIGNMENT);
+	  if ((ptr_t)deferred >= least_ha && (ptr_t)deferred <  greatest_ha) {
+	    PREFETCH((ptr_t)deferred);
+	    break;
+	  }
+	  if (current_p > limit) goto next_object;
+	}
+#     endif
+
+      while (current_p <= limit) {
+	/* Empirically, unrolling this loop doesn't help a lot.	*/
+	/* Since HC_PUSH_CONTENTS expands to a lot of code,	*/
+	/* we don't.						*/
+        current = *current_p;
+	FIXUP_POINTER(current);
+        PREFETCH((ptr_t)current_p + PREF_DIST*CACHE_LINE_SIZE);
+        if ((ptr_t)current >= least_ha && (ptr_t)current <  greatest_ha) {
+  	  /* Prefetch the contents of the object we just pushed.  It's	*/
+  	  /* likely we will need them soon.				*/
+  	  PREFETCH((ptr_t)current);
+          HC_PUSH_CONTENTS((ptr_t)current, mark_stack_top,
+  		           mark_stack_limit, current_p, exit2);
+        }
+        current_p = (word *)((char *)current_p + ALIGNMENT);
+      }
+
+#     ifndef SMALL_CONFIG
+	/* We still need to mark the entry we previously prefetched.	*/
+	/* We alrady know that it passes the preliminary pointer	*/
+	/* validity test.						*/
+        HC_PUSH_CONTENTS((ptr_t)deferred, mark_stack_top,
+  		         mark_stack_limit, current_p, exit4);
+	next_object:;
+#     endif
+    }
+  }
+  return mark_stack_top;
+}
+
+#ifdef PARALLEL_MARK
+
+/* We assume we have an ANSI C Compiler.	*/
+GC_bool GC_help_wanted = FALSE;
+unsigned GC_helper_count = 0;
+unsigned GC_active_count = 0;
+mse * VOLATILE GC_first_nonempty;
+word GC_mark_no = 0;
+
+#define LOCAL_MARK_STACK_SIZE HBLKSIZE
+	/* Under normal circumstances, this is big enough to guarantee	*/
+	/* We don't overflow half of it in a single call to 		*/
+	/* GC_mark_from.						*/
+
+
+/* Steal mark stack entries starting at mse low into mark stack local	*/
+/* until we either steal mse high, or we have max entries.		*/
+/* Return a pointer to the top of the local mark stack.		        */
+/* *next is replaced by a pointer to the next unscanned mark stack	*/
+/* entry.								*/
+mse * GC_steal_mark_stack(mse * low, mse * high, mse * local,
+			  unsigned max, mse **next)
+{
+    mse *p;
+    mse *top = local - 1;
+    unsigned i = 0;
+
+    /* Make sure that prior writes to the mark stack are visible. */
+    /* On some architectures, the fact that the reads are 	  */
+    /* volatile should suffice.					  */
+#   if !defined(IA64) && !defined(HP_PA) && !defined(I386)
+      GC_memory_barrier();
+#   endif
+    GC_ASSERT(high >= low-1 && high - low + 1 <= GC_mark_stack_size);
+    for (p = low; p <= high && i <= max; ++p) {
+	word descr = *(volatile word *) &(p -> mse_descr);
+	/* In the IA64 memory model, the following volatile store is	*/
+	/* ordered after this read of descr.  Thus a thread must read 	*/
+	/* the original nonzero value.  HP_PA appears to be similar,	*/
+	/* and if I'm reading the P4 spec correctly, X86 is probably 	*/
+	/* also OK.  In some other cases we need a barrier.		*/
+#       if !defined(IA64) && !defined(HP_PA) && !defined(I386)
+          GC_memory_barrier();
+#       endif
+	if (descr != 0) {
+	    *(volatile word *) &(p -> mse_descr) = 0;
+	    /* More than one thread may get this entry, but that's only */
+	    /* a minor performance problem.				*/
+	    ++top;
+	    top -> mse_descr = descr;
+	    top -> mse_start = p -> mse_start;
+	    GC_ASSERT(  (top -> mse_descr & GC_DS_TAGS) != GC_DS_LENGTH || 
+			top -> mse_descr < (ptr_t)GC_greatest_plausible_heap_addr
+			                   - (ptr_t)GC_least_plausible_heap_addr);
+	    /* If this is a big object, count it as			*/
+	    /* size/256 + 1 objects.					*/
+	    ++i;
+	    if ((descr & GC_DS_TAGS) == GC_DS_LENGTH) i += (descr >> 8);
+	}
+    }
+    *next = p;
+    return top;
+}
+
+/* Copy back a local mark stack.	*/
+/* low and high are inclusive bounds.	*/
+void GC_return_mark_stack(mse * low, mse * high)
+{
+    mse * my_top;
+    mse * my_start;
+    size_t stack_size;
+
+    if (high < low) return;
+    stack_size = high - low + 1;
+    GC_acquire_mark_lock();
+    my_top = GC_mark_stack_top;
+    my_start = my_top + 1;
+    if (my_start - GC_mark_stack + stack_size > GC_mark_stack_size) {
+#     ifdef CONDPRINT
+	if (GC_print_stats) {
+	  GC_printf0("No room to copy back mark stack.");
+	}
+#     endif
+      GC_mark_state = MS_INVALID;
+      GC_mark_stack_too_small = TRUE;
+      /* We drop the local mark stack.  We'll fix things later.	*/
+    } else {
+      BCOPY(low, my_start, stack_size * sizeof(mse));
+      GC_ASSERT(GC_mark_stack_top = my_top);
+#     if !defined(IA64) && !defined(HP_PA)
+        GC_memory_barrier();
+#     endif
+	/* On IA64, the volatile write acts as a release barrier. */
+      GC_mark_stack_top = my_top + stack_size;
+    }
+    GC_release_mark_lock();
+    GC_notify_all_marker();
+}
+
+/* Mark from the local mark stack.		*/
+/* On return, the local mark stack is empty.	*/
+/* But this may be achieved by copying the	*/
+/* local mark stack back into the global one.	*/
+void GC_do_local_mark(mse *local_mark_stack, mse *local_top)
+{
+    unsigned n;
+#   define N_LOCAL_ITERS 1
+
+#   ifdef GC_ASSERTIONS
+      /* Make sure we don't hold mark lock. */
+	GC_acquire_mark_lock();
+	GC_release_mark_lock();
+#   endif
+    for (;;) {
+        for (n = 0; n < N_LOCAL_ITERS; ++n) {
+	    local_top = GC_mark_from(local_top, local_mark_stack,
+				     local_mark_stack + LOCAL_MARK_STACK_SIZE);
+	    if (local_top < local_mark_stack) return;
+	    if (local_top - local_mark_stack >= LOCAL_MARK_STACK_SIZE/2) {
+	 	GC_return_mark_stack(local_mark_stack, local_top);
+		return;
+	    }
+	}
+	if (GC_mark_stack_top < GC_first_nonempty &&
+	    GC_active_count < GC_helper_count
+	    && local_top > local_mark_stack + 1) {
+	    /* Try to share the load, since the main stack is empty,	*/
+	    /* and helper threads are waiting for a refill.		*/
+	    /* The entries near the bottom of the stack are likely	*/
+	    /* to require more work.  Thus we return those, eventhough	*/
+	    /* it's harder.						*/
+	    mse * p;
+ 	    mse * new_bottom = local_mark_stack
+				+ (local_top - local_mark_stack)/2;
+	    GC_ASSERT(new_bottom > local_mark_stack
+		      && new_bottom < local_top);
+	    GC_return_mark_stack(local_mark_stack, new_bottom - 1);
+	    memmove(local_mark_stack, new_bottom,
+		    (local_top - new_bottom + 1) * sizeof(mse));
+	    local_top -= (new_bottom - local_mark_stack);
+	}
+    }
+}
+
+#define ENTRIES_TO_GET 5
+
+long GC_markers = 2;		/* Normally changed by thread-library-	*/
+				/* -specific code.			*/
+
+/* Mark using the local mark stack until the global mark stack is empty	*/
+/* and there are no active workers. Update GC_first_nonempty to reflect	*/
+/* progress.								*/
+/* Caller does not hold mark lock.					*/
+/* Caller has already incremented GC_helper_count.  We decrement it,	*/
+/* and maintain GC_active_count.					*/
+void GC_mark_local(mse *local_mark_stack, int id)
+{
+    mse * my_first_nonempty;
+
+    GC_acquire_mark_lock();
+    GC_active_count++;
+    my_first_nonempty = GC_first_nonempty;
+    GC_ASSERT(GC_first_nonempty >= GC_mark_stack && 
+	      GC_first_nonempty <= GC_mark_stack_top + 1);
+#   ifdef PRINTSTATS
+	GC_printf1("Starting mark helper %lu\n", (unsigned long)id);
+#   endif
+    GC_release_mark_lock();
+    for (;;) {
+  	size_t n_on_stack;
+        size_t n_to_get;
+	mse *next;
+	mse * my_top;
+	mse * local_top;
+        mse * global_first_nonempty = GC_first_nonempty;
+
+    	GC_ASSERT(my_first_nonempty >= GC_mark_stack && 
+		  my_first_nonempty <= GC_mark_stack_top + 1);
+    	GC_ASSERT(global_first_nonempty >= GC_mark_stack && 
+		  global_first_nonempty <= GC_mark_stack_top + 1);
+	if (my_first_nonempty < global_first_nonempty) {
+	    my_first_nonempty = global_first_nonempty;
+        } else if (global_first_nonempty < my_first_nonempty) {
+	    GC_compare_and_exchange((word *)(&GC_first_nonempty), 
+				   (word) global_first_nonempty,
+				   (word) my_first_nonempty);
+	    /* If this fails, we just go ahead, without updating	*/
+	    /* GC_first_nonempty.					*/
+	}
+	/* Perhaps we should also update GC_first_nonempty, if it */
+	/* is less.  But that would require using atomic updates. */
+	my_top = GC_mark_stack_top;
+	n_on_stack = my_top - my_first_nonempty + 1;
+        if (0 == n_on_stack) {
+	    GC_acquire_mark_lock();
+            my_top = GC_mark_stack_top;
+            n_on_stack = my_top - my_first_nonempty + 1;
+	    if (0 == n_on_stack) {
+		GC_active_count--;
+		GC_ASSERT(GC_active_count <= GC_helper_count);
+		/* Other markers may redeposit objects	*/
+		/* on the stack.				*/
+		if (0 == GC_active_count) GC_notify_all_marker();
+		while (GC_active_count > 0
+		       && GC_first_nonempty > GC_mark_stack_top) {
+		    /* We will be notified if either GC_active_count	*/
+		    /* reaches zero, or if more objects are pushed on	*/
+		    /* the global mark stack.				*/
+		    GC_wait_marker();
+		}
+		if (GC_active_count == 0 &&
+		    GC_first_nonempty > GC_mark_stack_top) { 
+		    GC_bool need_to_notify = FALSE;
+		    /* The above conditions can't be falsified while we	*/
+		    /* hold the mark lock, since neither 		*/
+		    /* GC_active_count nor GC_mark_stack_top can	*/
+		    /* change.  GC_first_nonempty can only be		*/
+		    /* incremented asynchronously.  Thus we know that	*/
+		    /* both conditions actually held simultaneously.	*/
+		    GC_helper_count--;
+		    if (0 == GC_helper_count) need_to_notify = TRUE;
+#		    ifdef PRINTSTATS
+		      GC_printf1(
+		        "Finished mark helper %lu\n", (unsigned long)id);
+#   		    endif
+		    GC_release_mark_lock();
+		    if (need_to_notify) GC_notify_all_marker();
+		    return;
+		}
+		/* else there's something on the stack again, or	*/
+		/* another helper may push something.			*/
+		GC_active_count++;
+	        GC_ASSERT(GC_active_count > 0);
+		GC_release_mark_lock();
+		continue;
+	    } else {
+		GC_release_mark_lock();
+	    }
+	}
+	n_to_get = ENTRIES_TO_GET;
+	if (n_on_stack < 2 * ENTRIES_TO_GET) n_to_get = 1;
+	local_top = GC_steal_mark_stack(my_first_nonempty, my_top,
+					local_mark_stack, n_to_get,
+				        &my_first_nonempty);
+        GC_ASSERT(my_first_nonempty >= GC_mark_stack && 
+	          my_first_nonempty <= GC_mark_stack_top + 1);
+	GC_do_local_mark(local_mark_stack, local_top);
+    }
+}
+
+/* Perform Parallel mark.			*/
+/* We hold the GC lock, not the mark lock.	*/
+/* Currently runs until the mark stack is	*/
+/* empty.					*/
+void GC_do_parallel_mark()
+{
+    mse local_mark_stack[LOCAL_MARK_STACK_SIZE];
+    mse * local_top;
+    mse * my_top;
+
+    GC_acquire_mark_lock();
+    GC_ASSERT(I_HOLD_LOCK());
+    /* This could be a GC_ASSERT, but it seems safer to keep it on	*/
+    /* all the time, especially since it's cheap.			*/
+    if (GC_help_wanted || GC_active_count != 0 || GC_helper_count != 0)
+	ABORT("Tried to start parallel mark in bad state");
+#   ifdef PRINTSTATS
+	GC_printf1("Starting marking for mark phase number %lu\n",
+		   (unsigned long)GC_mark_no);
+#   endif
+    GC_first_nonempty = GC_mark_stack;
+    GC_active_count = 0;
+    GC_helper_count = 1;
+    GC_help_wanted = TRUE;
+    GC_release_mark_lock();
+    GC_notify_all_marker();
+	/* Wake up potential helpers.	*/
+    GC_mark_local(local_mark_stack, 0);
+    GC_acquire_mark_lock();
+    GC_help_wanted = FALSE;
+    /* Done; clean up.	*/
+    while (GC_helper_count > 0) GC_wait_marker();
+    /* GC_helper_count cannot be incremented while GC_help_wanted == FALSE */
+#   ifdef PRINTSTATS
+	GC_printf1(
+	    "Finished marking for mark phase number %lu\n",
+	    (unsigned long)GC_mark_no);
+#   endif
+    GC_mark_no++;
+    GC_release_mark_lock();
+    GC_notify_all_marker();
+}
+
+
+/* Try to help out the marker, if it's running.	        */
+/* We do not hold the GC lock, but the requestor does.	*/
+void GC_help_marker(word my_mark_no)
+{
+    mse local_mark_stack[LOCAL_MARK_STACK_SIZE];
+    unsigned my_id;
+    mse * my_first_nonempty;
+
+    if (!GC_parallel) return;
+    GC_acquire_mark_lock();
+    while (GC_mark_no < my_mark_no
+           || !GC_help_wanted && GC_mark_no == my_mark_no) {
+      GC_wait_marker();
+    }
+    my_id = GC_helper_count;
+    if (GC_mark_no != my_mark_no || my_id >= GC_markers) {
+      /* Second test is useful only if original threads can also	*/
+      /* act as helpers.  Under Linux they can't.			*/
+      GC_release_mark_lock();
+      return;
+    }
+    GC_helper_count = my_id + 1;
+    GC_release_mark_lock();
+    GC_mark_local(local_mark_stack, my_id);
+    /* GC_mark_local decrements GC_helper_count. */
+}
+
+#endif /* PARALLEL_MARK */
+
+/* Allocate or reallocate space for mark stack of size s words  */
+/* May silently fail.						*/
+static void alloc_mark_stack(n)
+word n;
+{
+    mse * new_stack = (mse *)GC_scratch_alloc(n * sizeof(struct GC_ms_entry));
+    
+    GC_mark_stack_too_small = FALSE;
+    if (GC_mark_stack_size != 0) {
+        if (new_stack != 0) {
+          word displ = (word)GC_mark_stack & (GC_page_size - 1);
+          signed_word size = GC_mark_stack_size * sizeof(struct GC_ms_entry);
+          
+          /* Recycle old space */
+	      if (0 != displ) displ = GC_page_size - displ;
+	      size = (size - displ) & ~(GC_page_size - 1);
+	      if (size > 0) {
+	        GC_add_to_heap((struct hblk *)
+	      			((word)GC_mark_stack + displ), (word)size);
+	      }
+          GC_mark_stack = new_stack;
+          GC_mark_stack_size = n;
+	  GC_mark_stack_limit = new_stack + n;
+#	  ifdef CONDPRINT
+	    if (GC_print_stats) {
+	      GC_printf1("Grew mark stack to %lu frames\n",
+		    	 (unsigned long) GC_mark_stack_size);
+	    }
+#	  endif
+        } else {
+#	  ifdef CONDPRINT
+	    if (GC_print_stats) {
+	      GC_printf1("Failed to grow mark stack to %lu frames\n",
+		    	 (unsigned long) n);
+	    }
+#	  endif
+        }
+    } else {
+        if (new_stack == 0) {
+            GC_err_printf0("No space for mark stack\n");
+            EXIT();
+        }
+        GC_mark_stack = new_stack;
+        GC_mark_stack_size = n;
+	GC_mark_stack_limit = new_stack + n;
+    }
+    GC_mark_stack_top = GC_mark_stack-1;
+}
+
+void GC_mark_init()
+{
+    alloc_mark_stack(INITIAL_MARK_STACK_SIZE);
+}
+
+/*
+ * Push all locations between b and t onto the mark stack.
+ * b is the first location to be checked. t is one past the last
+ * location to be checked.
+ * Should only be used if there is no possibility of mark stack
+ * overflow.
+ */
+void GC_push_all(bottom, top)
+ptr_t bottom;
+ptr_t top;
+{
+    register word length;
+    
+    bottom = (ptr_t)(((word) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1));
+    top = (ptr_t)(((word) top) & ~(ALIGNMENT-1));
+    if (top == 0 || bottom == top) return;
+    GC_mark_stack_top++;
+    if (GC_mark_stack_top >= GC_mark_stack_limit) {
+	ABORT("unexpected mark stack overflow");
+    }
+    length = top - bottom;
+#   if GC_DS_TAGS > ALIGNMENT - 1
+	length += GC_DS_TAGS;
+	length &= ~GC_DS_TAGS;
+#   endif
+    GC_mark_stack_top -> mse_start = (word *)bottom;
+    GC_mark_stack_top -> mse_descr = length;
+}
+
+/*
+ * Analogous to the above, but push only those pages h with dirty_fn(h) != 0.
+ * We use push_fn to actually push the block.
+ * Used both to selectively push dirty pages, or to push a block
+ * in piecemeal fashion, to allow for more marking concurrency.
+ * Will not overflow mark stack if push_fn pushes a small fixed number
+ * of entries.  (This is invoked only if push_fn pushes a single entry,
+ * or if it marks each object before pushing it, thus ensuring progress
+ * in the event of a stack overflow.)
+ */
+void GC_push_selected(bottom, top, dirty_fn, push_fn)
+ptr_t bottom;
+ptr_t top;
+int (*dirty_fn) GC_PROTO((struct hblk * h));
+void (*push_fn) GC_PROTO((ptr_t bottom, ptr_t top));
+{
+    register struct hblk * h;
+
+    bottom = (ptr_t)(((long) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1));
+    top = (ptr_t)(((long) top) & ~(ALIGNMENT-1));
+
+    if (top == 0 || bottom == top) return;
+    h = HBLKPTR(bottom + HBLKSIZE);
+    if (top <= (ptr_t) h) {
+  	if ((*dirty_fn)(h-1)) {
+	    (*push_fn)(bottom, top);
+	}
+	return;
+    }
+    if ((*dirty_fn)(h-1)) {
+        (*push_fn)(bottom, (ptr_t)h);
+    }
+    while ((ptr_t)(h+1) <= top) {
+	if ((*dirty_fn)(h)) {
+	    if ((word)(GC_mark_stack_top - GC_mark_stack)
+		> 3 * GC_mark_stack_size / 4) {
+	 	/* Danger of mark stack overflow */
+		(*push_fn)((ptr_t)h, top);
+		return;
+	    } else {
+		(*push_fn)((ptr_t)h, (ptr_t)(h+1));
+	    }
+	}
+	h++;
+    }
+    if ((ptr_t)h != top) {
+	if ((*dirty_fn)(h)) {
+            (*push_fn)((ptr_t)h, top);
+        }
+    }
+    if (GC_mark_stack_top >= GC_mark_stack_limit) {
+        ABORT("unexpected mark stack overflow");
+    }
+}
+
+# ifndef SMALL_CONFIG
+
+#ifdef PARALLEL_MARK
+    /* Break up root sections into page size chunks to better spread 	*/
+    /* out work.							*/
+    GC_bool GC_true_func(struct hblk *h) { return TRUE; }
+#   define GC_PUSH_ALL(b,t) GC_push_selected(b,t,GC_true_func,GC_push_all);
+#else
+#   define GC_PUSH_ALL(b,t) GC_push_all(b,t);
+#endif
+
+
+void GC_push_conditional(bottom, top, all)
+ptr_t bottom;
+ptr_t top;
+int all;
+{
+    if (all) {
+      if (GC_dirty_maintained) {
+#	ifdef PROC_VDB
+	    /* Pages that were never dirtied cannot contain pointers	*/
+	    GC_push_selected(bottom, top, GC_page_was_ever_dirty, GC_push_all);
+#	else
+	    GC_push_all(bottom, top);
+#	endif
+      } else {
+      	GC_push_all(bottom, top);
+      }
+    } else {
+	GC_push_selected(bottom, top, GC_page_was_dirty, GC_push_all);
+    }
+}
+#endif
+
+# if defined(MSWIN32) || defined(MSWINCE)
+  void __cdecl GC_push_one(p)
+# else
+  void GC_push_one(p)
+# endif
+word p;
+{
+    GC_PUSH_ONE_STACK(p, MARKED_FROM_REGISTER);
+}
+
+struct GC_ms_entry *GC_mark_and_push(obj, mark_stack_ptr, mark_stack_limit, src)
+GC_PTR obj;
+struct GC_ms_entry * mark_stack_ptr;
+struct GC_ms_entry * mark_stack_limit;
+GC_PTR *src;
+{
+   PREFETCH(obj);
+   PUSH_CONTENTS(obj, mark_stack_ptr /* modified */, mark_stack_limit, src,
+		 was_marked /* internally generated exit label */);
+   return mark_stack_ptr;
+}
+
+# ifdef __STDC__
+#   define BASE(p) (word)GC_base((void *)(p))
+# else
+#   define BASE(p) (word)GC_base((char *)(p))
+# endif
+
+/* Mark and push (i.e. gray) a single object p onto the main	*/
+/* mark stack.  Consider p to be valid if it is an interior	*/
+/* pointer.							*/
+/* The object p has passed a preliminary pointer validity	*/
+/* test, but we do not definitely know whether it is valid.	*/
+/* Mark bits are NOT atomically updated.  Thus this must be the	*/
+/* only thread setting them.					*/
+# if defined(PRINT_BLACK_LIST) || defined(KEEP_BACK_PTRS)
+    void GC_mark_and_push_stack(p, source)
+    ptr_t source;
+# else
+    void GC_mark_and_push_stack(p)
+#   define source 0
+# endif
+register word p;
+{
+    register word r;
+    register hdr * hhdr; 
+    register int displ;
+  
+    GET_HDR(p, hhdr);
+    if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
+        if (hhdr != 0) {
+          r = BASE(p);
+	  hhdr = HDR(r);
+	  displ = BYTES_TO_WORDS(HBLKDISPL(r));
+	}
+    } else {
+        register map_entry_type map_entry;
+        
+        displ = HBLKDISPL(p);
+        map_entry = MAP_ENTRY((hhdr -> hb_map), displ);
+        if (map_entry >= MAX_OFFSET) {
+          if (map_entry == OFFSET_TOO_BIG || !GC_all_interior_pointers) {
+              r = BASE(p);
+	      displ = BYTES_TO_WORDS(HBLKDISPL(r));
+	      if (r == 0) hhdr = 0;
+          } else {
+	      /* Offset invalid, but map reflects interior pointers 	*/
+              hhdr = 0;
+          }
+        } else {
+          displ = BYTES_TO_WORDS(displ);
+          displ -= map_entry;
+          r = (word)((word *)(HBLKPTR(p)) + displ);
+        }
+    }
+    /* If hhdr != 0 then r == GC_base(p), only we did it faster. */
+    /* displ is the word index within the block.		 */
+    if (hhdr == 0) {
+#	ifdef PRINT_BLACK_LIST
+	  GC_add_to_black_list_stack(p, source);
+#	else
+	  GC_add_to_black_list_stack(p);
+#	endif
+#	undef source  /* In case we had to define it. */
+    } else {
+	if (!mark_bit_from_hdr(hhdr, displ)) {
+	    set_mark_bit_from_hdr(hhdr, displ);
+ 	    GC_STORE_BACK_PTR(source, (ptr_t)r);
+	    PUSH_OBJ((word *)r, hhdr, GC_mark_stack_top,
+	             GC_mark_stack_limit);
+	}
+    }
+}
+
+# ifdef TRACE_BUF
+
+# define TRACE_ENTRIES 1000
+
+struct trace_entry {
+    char * kind;
+    word gc_no;
+    word words_allocd;
+    word arg1;
+    word arg2;
+} GC_trace_buf[TRACE_ENTRIES];
+
+int GC_trace_buf_ptr = 0;
+
+void GC_add_trace_entry(char *kind, word arg1, word arg2)
+{
+    GC_trace_buf[GC_trace_buf_ptr].kind = kind;
+    GC_trace_buf[GC_trace_buf_ptr].gc_no = GC_gc_no;
+    GC_trace_buf[GC_trace_buf_ptr].words_allocd = GC_words_allocd;
+    GC_trace_buf[GC_trace_buf_ptr].arg1 = arg1 ^ 0x80000000;
+    GC_trace_buf[GC_trace_buf_ptr].arg2 = arg2 ^ 0x80000000;
+    GC_trace_buf_ptr++;
+    if (GC_trace_buf_ptr >= TRACE_ENTRIES) GC_trace_buf_ptr = 0;
+}
+
+void GC_print_trace(word gc_no, GC_bool lock)
+{
+    int i;
+    struct trace_entry *p;
+    
+    if (lock) LOCK();
+    for (i = GC_trace_buf_ptr-1; i != GC_trace_buf_ptr; i--) {
+    	if (i < 0) i = TRACE_ENTRIES-1;
+    	p = GC_trace_buf + i;
+    	if (p -> gc_no < gc_no || p -> kind == 0) return;
+    	printf("Trace:%s (gc:%d,words:%d) 0x%X, 0x%X\n",
+    		p -> kind, p -> gc_no, p -> words_allocd,
+    		(p -> arg1) ^ 0x80000000, (p -> arg2) ^ 0x80000000);
+    }
+    printf("Trace incomplete\n");
+    if (lock) UNLOCK();
+}
+
+# endif /* TRACE_BUF */
+
+/*
+ * A version of GC_push_all that treats all interior pointers as valid
+ * and scans the entire region immediately, in case the contents
+ * change.
+ */
+void GC_push_all_eager(bottom, top)
+ptr_t bottom;
+ptr_t top;
+{
+    word * b = (word *)(((word) bottom + ALIGNMENT-1) & ~(ALIGNMENT-1));
+    word * t = (word *)(((word) top) & ~(ALIGNMENT-1));
+    register word *p;
+    register word q;
+    register word *lim;
+    register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
+    register ptr_t least_ha = GC_least_plausible_heap_addr;
+#   define GC_greatest_plausible_heap_addr greatest_ha
+#   define GC_least_plausible_heap_addr least_ha
+
+    if (top == 0) return;
+    /* check all pointers in range and push if they appear	*/
+    /* to be valid.						*/
+      lim = t - 1 /* longword */;
+      for (p = b; p <= lim; p = (word *)(((char *)p) + ALIGNMENT)) {
+	q = *p;
+	GC_PUSH_ONE_STACK(q, p);
+      }
+#   undef GC_greatest_plausible_heap_addr
+#   undef GC_least_plausible_heap_addr
+}
+
+#ifndef THREADS
+/*
+ * A version of GC_push_all that treats all interior pointers as valid
+ * and scans part of the area immediately, to make sure that saved
+ * register values are not lost.
+ * Cold_gc_frame delimits the stack section that must be scanned
+ * eagerly.  A zero value indicates that no eager scanning is needed.
+ */
+void GC_push_all_stack_partially_eager(bottom, top, cold_gc_frame)
+ptr_t bottom;
+ptr_t top;
+ptr_t cold_gc_frame;
+{
+  if (!NEED_FIXUP_POINTER && GC_all_interior_pointers) {
+#   define EAGER_BYTES 1024
+    /* Push the hot end of the stack eagerly, so that register values   */
+    /* saved inside GC frames are marked before they disappear.		*/
+    /* The rest of the marking can be deferred until later.		*/
+    if (0 == cold_gc_frame) {
+	GC_push_all_stack(bottom, top);
+	return;
+    }
+    GC_ASSERT(bottom <= cold_gc_frame && cold_gc_frame <= top);
+#   ifdef STACK_GROWS_DOWN
+	GC_push_all(cold_gc_frame - sizeof(ptr_t), top);
+	GC_push_all_eager(bottom, cold_gc_frame);
+#   else /* STACK_GROWS_UP */
+	GC_push_all(bottom, cold_gc_frame + sizeof(ptr_t));
+	GC_push_all_eager(cold_gc_frame, top);
+#   endif /* STACK_GROWS_UP */
+  } else {
+    GC_push_all_eager(bottom, top);
+  }
+# ifdef TRACE_BUF
+      GC_add_trace_entry("GC_push_all_stack", bottom, top);
+# endif
+}
+#endif /* !THREADS */
+
+void GC_push_all_stack(bottom, top)
+ptr_t bottom;
+ptr_t top;
+{
+  if (!NEED_FIXUP_POINTER && GC_all_interior_pointers) {
+    GC_push_all(bottom, top);
+  } else {
+    GC_push_all_eager(bottom, top);
+  }
+}
+
+#if !defined(SMALL_CONFIG) && !defined(USE_MARK_BYTES)
+/* Push all objects reachable from marked objects in the given block */
+/* of size 1 objects.						     */
+void GC_push_marked1(h, hhdr)
+struct hblk *h;
+register hdr * hhdr;
+{
+    word * mark_word_addr = &(hhdr->hb_marks[0]);
+    register word *p;
+    word *plim;
+    register int i;
+    register word q;
+    register word mark_word;
+    register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
+    register ptr_t least_ha = GC_least_plausible_heap_addr;
+    register mse * mark_stack_top = GC_mark_stack_top;
+    register mse * mark_stack_limit = GC_mark_stack_limit;
+#   define GC_mark_stack_top mark_stack_top
+#   define GC_mark_stack_limit mark_stack_limit
+#   define GC_greatest_plausible_heap_addr greatest_ha
+#   define GC_least_plausible_heap_addr least_ha
+    
+    p = (word *)(h->hb_body);
+    plim = (word *)(((word)h) + HBLKSIZE);
+
+    /* go through all words in block */
+	while( p < plim )  {
+	    mark_word = *mark_word_addr++;
+	    i = 0;
+	    while(mark_word != 0) {
+	      if (mark_word & 1) {
+	          q = p[i];
+	          GC_PUSH_ONE_HEAP(q, p + i);
+	      }
+	      i++;
+	      mark_word >>= 1;
+	    }
+	    p += WORDSZ;
+	}
+#   undef GC_greatest_plausible_heap_addr
+#   undef GC_least_plausible_heap_addr        
+#   undef GC_mark_stack_top
+#   undef GC_mark_stack_limit
+    GC_mark_stack_top = mark_stack_top;
+}
+
+
+#ifndef UNALIGNED
+
+/* Push all objects reachable from marked objects in the given block */
+/* of size 2 objects.						     */
+void GC_push_marked2(h, hhdr)
+struct hblk *h;
+register hdr * hhdr;
+{
+    word * mark_word_addr = &(hhdr->hb_marks[0]);
+    register word *p;
+    word *plim;
+    register int i;
+    register word q;
+    register word mark_word;
+    register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
+    register ptr_t least_ha = GC_least_plausible_heap_addr;
+    register mse * mark_stack_top = GC_mark_stack_top;
+    register mse * mark_stack_limit = GC_mark_stack_limit;
+#   define GC_mark_stack_top mark_stack_top
+#   define GC_mark_stack_limit mark_stack_limit
+#   define GC_greatest_plausible_heap_addr greatest_ha
+#   define GC_least_plausible_heap_addr least_ha
+    
+    p = (word *)(h->hb_body);
+    plim = (word *)(((word)h) + HBLKSIZE);
+
+    /* go through all words in block */
+	while( p < plim )  {
+	    mark_word = *mark_word_addr++;
+	    i = 0;
+	    while(mark_word != 0) {
+	      if (mark_word & 1) {
+	          q = p[i];
+	          GC_PUSH_ONE_HEAP(q, p + i);
+	          q = p[i+1];
+	          GC_PUSH_ONE_HEAP(q, p + i);
+	      }
+	      i += 2;
+	      mark_word >>= 2;
+	    }
+	    p += WORDSZ;
+	}
+#   undef GC_greatest_plausible_heap_addr
+#   undef GC_least_plausible_heap_addr        
+#   undef GC_mark_stack_top
+#   undef GC_mark_stack_limit
+    GC_mark_stack_top = mark_stack_top;
+}
+
+/* Push all objects reachable from marked objects in the given block */
+/* of size 4 objects.						     */
+/* There is a risk of mark stack overflow here.  But we handle that. */
+/* And only unmarked objects get pushed, so it's not very likely.    */
+void GC_push_marked4(h, hhdr)
+struct hblk *h;
+register hdr * hhdr;
+{
+    word * mark_word_addr = &(hhdr->hb_marks[0]);
+    register word *p;
+    word *plim;
+    register int i;
+    register word q;
+    register word mark_word;
+    register ptr_t greatest_ha = GC_greatest_plausible_heap_addr;
+    register ptr_t least_ha = GC_least_plausible_heap_addr;
+    register mse * mark_stack_top = GC_mark_stack_top;
+    register mse * mark_stack_limit = GC_mark_stack_limit;
+#   define GC_mark_stack_top mark_stack_top
+#   define GC_mark_stack_limit mark_stack_limit
+#   define GC_greatest_plausible_heap_addr greatest_ha
+#   define GC_least_plausible_heap_addr least_ha
+    
+    p = (word *)(h->hb_body);
+    plim = (word *)(((word)h) + HBLKSIZE);
+
+    /* go through all words in block */
+	while( p < plim )  {
+	    mark_word = *mark_word_addr++;
+	    i = 0;
+	    while(mark_word != 0) {
+	      if (mark_word & 1) {
+	          q = p[i];
+	          GC_PUSH_ONE_HEAP(q, p + i);
+	          q = p[i+1];
+	          GC_PUSH_ONE_HEAP(q, p + i + 1);
+	          q = p[i+2];
+	          GC_PUSH_ONE_HEAP(q, p + i + 2);
+	          q = p[i+3];
+	          GC_PUSH_ONE_HEAP(q, p + i + 3);
+	      }
+	      i += 4;
+	      mark_word >>= 4;
+	    }
+	    p += WORDSZ;
+	}
+#   undef GC_greatest_plausible_heap_addr
+#   undef GC_least_plausible_heap_addr        
+#   undef GC_mark_stack_top
+#   undef GC_mark_stack_limit
+    GC_mark_stack_top = mark_stack_top;
+}
+
+#endif /* UNALIGNED */
+
+#endif /* SMALL_CONFIG */
+
+/* Push all objects reachable from marked objects in the given block */
+void GC_push_marked(h, hhdr)
+struct hblk *h;
+register hdr * hhdr;
+{
+    register int sz = hhdr -> hb_sz;
+    register int descr = hhdr -> hb_descr;
+    register word * p;
+    register int word_no;
+    register word * lim;
+    register mse * GC_mark_stack_top_reg;
+    register mse * mark_stack_limit = GC_mark_stack_limit;
+    
+    /* Some quick shortcuts: */
+	if ((0 | GC_DS_LENGTH) == descr) return;
+        if (GC_block_empty(hhdr)/* nothing marked */) return;
+    GC_n_rescuing_pages++;
+    GC_objects_are_marked = TRUE;
+    if (sz > MAXOBJSZ) {
+        lim = (word *)h;
+    } else {
+        lim = (word *)(h + 1) - sz;
+    }
+    
+    switch(sz) {
+#   if !defined(SMALL_CONFIG) && !defined(USE_MARK_BYTES)   
+     case 1:
+       GC_push_marked1(h, hhdr);
+       break;
+#   endif
+#   if !defined(SMALL_CONFIG) && !defined(UNALIGNED) && \
+       !defined(USE_MARK_BYTES)
+     case 2:
+       GC_push_marked2(h, hhdr);
+       break;
+     case 4:
+       GC_push_marked4(h, hhdr);
+       break;
+#   endif       
+     default:
+      GC_mark_stack_top_reg = GC_mark_stack_top;
+      for (p = (word *)h, word_no = 0; p <= lim; p += sz, word_no += sz) {
+         if (mark_bit_from_hdr(hhdr, word_no)) {
+           /* Mark from fields inside the object */
+             PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top_reg, mark_stack_limit);
+#	     ifdef GATHERSTATS
+		/* Subtract this object from total, since it was	*/
+		/* added in twice.					*/
+		GC_composite_in_use -= sz;
+#	     endif
+         }
+      }
+      GC_mark_stack_top = GC_mark_stack_top_reg;
+    }
+}
+
+#ifndef SMALL_CONFIG
+/* Test whether any page in the given block is dirty	*/
+GC_bool GC_block_was_dirty(h, hhdr)
+struct hblk *h;
+register hdr * hhdr;
+{
+    register int sz = hhdr -> hb_sz;
+    
+    if (sz <= MAXOBJSZ) {
+         return(GC_page_was_dirty(h));
+    } else {
+    	 register ptr_t p = (ptr_t)h;
+         sz = WORDS_TO_BYTES(sz);
+         while (p < (ptr_t)h + sz) {
+             if (GC_page_was_dirty((struct hblk *)p)) return(TRUE);
+             p += HBLKSIZE;
+         }
+         return(FALSE);
+    }
+}
+#endif /* SMALL_CONFIG */
+
+/* Similar to GC_push_next_marked, but return address of next block	*/
+struct hblk * GC_push_next_marked(h)
+struct hblk *h;
+{
+    register hdr * hhdr;
+    
+    h = GC_next_used_block(h);
+    if (h == 0) return(0);
+    hhdr = HDR(h);
+    GC_push_marked(h, hhdr);
+    return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz));
+}
+
+#ifndef SMALL_CONFIG
+/* Identical to above, but mark only from dirty pages	*/
+struct hblk * GC_push_next_marked_dirty(h)
+struct hblk *h;
+{
+    register hdr * hhdr;
+    
+    if (!GC_dirty_maintained) { ABORT("dirty bits not set up"); }
+    for (;;) {
+        h = GC_next_used_block(h);
+        if (h == 0) return(0);
+        hhdr = HDR(h);
+#	ifdef STUBBORN_ALLOC
+          if (hhdr -> hb_obj_kind == STUBBORN) {
+            if (GC_page_was_changed(h) && GC_block_was_dirty(h, hhdr)) {
+                break;
+            }
+          } else {
+            if (GC_block_was_dirty(h, hhdr)) break;
+          }
+#	else
+	  if (GC_block_was_dirty(h, hhdr)) break;
+#	endif
+        h += OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz);
+    }
+    GC_push_marked(h, hhdr);
+    return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz));
+}
+#endif
+
+/* Similar to above, but for uncollectable pages.  Needed since we	*/
+/* do not clear marks for such pages, even for full collections.	*/
+struct hblk * GC_push_next_marked_uncollectable(h)
+struct hblk *h;
+{
+    register hdr * hhdr = HDR(h);
+    
+    for (;;) {
+        h = GC_next_used_block(h);
+        if (h == 0) return(0);
+        hhdr = HDR(h);
+	if (hhdr -> hb_obj_kind == UNCOLLECTABLE) break;
+        h += OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz);
+    }
+    GC_push_marked(h, hhdr);
+    return(h + OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz));
+}
+
+