Merged GC 5.0alpha4 with local changes, plus:

	* Makefile.in: Rebuilt.
	* Makefile.am (gctest_LDADD): Added THREADLIB.
	(TESTS): New macro.
	* configure: Rebuilt.
	* configure.in (INCLUDES): New subst.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@30332 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 489 insertions, 170 deletions

diff --git a/boehm-gc/allchblk.c b/boehm-gc/allchblk.c
index 7a5a3a1c3ab..189b94214a7 100644
--- a/boehm-gc/allchblk.c
+++ b/boehm-gc/allchblk.c
@@ -1,7 +1,8 @@
 /* 
  * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
- * Copyright (c) 1998 by Silicon Graphics.  All rights reserved.
+ * Copyright (c) 1998-1999 by Silicon Graphics.  All rights reserved.
+ * Copyright (c) 1999 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.
@@ -12,7 +13,6 @@
  * provided the above notices are retained, and a notice that the code was
  * modified is included with the above copyright notice.
  */
-/* Boehm, August 9, 1995 5:08 pm PDT */
 
 #define DEBUG
 #undef DEBUG
@@ -21,39 +21,68 @@
 
 
 /*
- * allocate/free routines for heap blocks
- * Note that everything called from outside the garbage collector
- * should be prepared to abort at any point as the result of a signal.
+ * Free heap blocks are kept on one of several free lists,
+ * depending on the size of the block.  Each free list is doubly linked.
+ * Adjacent free blocks are coalesced.
  */
 
-/*
- * Free heap blocks are kept on a list sorted by address.
- * The hb_hdr.hbh_sz field of a free heap block contains the length
- * (in bytes) of the entire block.
- * Neighbors are coalesced.
- */
  
 # define MAX_BLACK_LIST_ALLOC (2*HBLKSIZE)
 		/* largest block we will allocate starting on a black   */
 		/* listed block.  Must be >= HBLKSIZE.			*/
 
-struct hblk * GC_hblkfreelist = 0;
 
-struct hblk *GC_savhbp = (struct hblk *)0;  /* heap block preceding next */
-					 /* block to be examined by   */
-					 /* GC_allochblk.                */
+# define UNIQUE_THRESHOLD 32
+	/* Sizes up to this many HBLKs each have their own free list    */
+# define HUGE_THRESHOLD 256
+	/* Sizes of at least this many heap blocks are mapped to a	*/
+	/* single free list.						*/
+# define FL_COMPRESSION 8
+	/* In between sizes map this many distinct sizes to a single	*/
+	/* bin.								*/
+
+# define N_HBLK_FLS (HUGE_THRESHOLD - UNIQUE_THRESHOLD)/FL_COMPRESSION \
+				 + UNIQUE_THRESHOLD
+
+struct hblk * GC_hblkfreelist[N_HBLK_FLS+1] = { 0 };
+
+/* Map a number of blocks to the appropriate large block free list index. */
+int GC_hblk_fl_from_blocks(blocks_needed)
+word blocks_needed;
+{
+    if (blocks_needed <= UNIQUE_THRESHOLD) return blocks_needed;
+    if (blocks_needed >= HUGE_THRESHOLD) return N_HBLK_FLS;
+    return (blocks_needed - UNIQUE_THRESHOLD)/FL_COMPRESSION
+					+ UNIQUE_THRESHOLD;
+    
+}
+
+# define HBLK_IS_FREE(hdr) ((hdr) -> hb_map == GC_invalid_map)
+# define PHDR(hhdr) HDR(hhdr -> hb_prev)
+# define NHDR(hhdr) HDR(hhdr -> hb_next)
+
+# ifdef USE_MUNMAP
+#   define IS_MAPPED(hhdr) (((hhdr) -> hb_flags & WAS_UNMAPPED) == 0)
+# else  /* !USE_MMAP */
+#   define IS_MAPPED(hhdr) 1
+# endif /* USE_MUNMAP */
 
 # if !defined(NO_DEBUGGING)
 void GC_print_hblkfreelist()
 {
-    struct hblk * h = GC_hblkfreelist;
+    struct hblk * h;
     word total_free = 0;
-    hdr * hhdr = HDR(h);
+    hdr * hhdr;
     word sz;
+    int i;
     
-    while (h != 0) {
+    for (i = 0; i <= N_HBLK_FLS; ++i) {
+      h = GC_hblkfreelist[i];
+      if (0 != h) GC_printf1("Free list %ld:\n", (unsigned long)i);
+      while (h != 0) {
+        hhdr = HDR(h);
         sz = hhdr -> hb_sz;
-    	GC_printf2("0x%lx size %lu ", (unsigned long)h, (unsigned long)sz);
+    	GC_printf2("\t0x%lx size %lu ", (unsigned long)h, (unsigned long)sz);
     	total_free += sz;
         if (GC_is_black_listed(h, HBLKSIZE) != 0) {
              GC_printf0("start black listed\n");
@@ -63,11 +92,90 @@ void GC_print_hblkfreelist()
              GC_printf0("not black listed\n");
         }
         h = hhdr -> hb_next;
-        hhdr = HDR(h);
+      }
+    }
+    if (total_free != GC_large_free_bytes) {
+	GC_printf1("GC_large_free_bytes = %lu (INCONSISTENT!!)\n",
+		   (unsigned long) GC_large_free_bytes);
     }
     GC_printf1("Total of %lu bytes on free list\n", (unsigned long)total_free);
 }
 
+/* Return the free list index on which the block described by the header */
+/* appears, or -1 if it appears nowhere.				 */
+int free_list_index_of(wanted)
+hdr * wanted;
+{
+    struct hblk * h;
+    hdr * hhdr;
+    int i;
+    
+    for (i = 0; i <= N_HBLK_FLS; ++i) {
+      h = GC_hblkfreelist[i];
+      while (h != 0) {
+        hhdr = HDR(h);
+	if (hhdr == wanted) return i;
+        h = hhdr -> hb_next;
+      }
+    }
+    return -1;
+}
+
+void GC_dump_regions()
+{
+    unsigned i;
+    ptr_t start, end;
+    ptr_t p;
+    size_t bytes;
+    hdr *hhdr;
+    for (i = 0; i < GC_n_heap_sects; ++i) {
+	start = GC_heap_sects[i].hs_start;
+	bytes = GC_heap_sects[i].hs_bytes;
+	end = start + bytes;
+	/* Merge in contiguous sections.	*/
+	  while (i+1 < GC_n_heap_sects && GC_heap_sects[i+1].hs_start == end) {
+	    ++i;
+	    end = GC_heap_sects[i].hs_start + GC_heap_sects[i].hs_bytes;
+	  }
+	GC_printf2("***Section from 0x%lx to 0x%lx\n", start, end);
+	for (p = start; p < end;) {
+	    hhdr = HDR(p);
+	    GC_printf1("\t0x%lx ", (unsigned long)p);
+	    if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
+		GC_printf1("Missing header!!\n", hhdr);
+		p += HBLKSIZE;
+		continue;
+	    }
+	    if (HBLK_IS_FREE(hhdr)) {
+                int correct_index = GC_hblk_fl_from_blocks(
+					divHBLKSZ(hhdr -> hb_sz));
+	        int actual_index;
+		
+		GC_printf1("\tfree block of size 0x%lx bytes",
+			   (unsigned long)(hhdr -> hb_sz));
+	 	if (IS_MAPPED(hhdr)) {
+		    GC_printf0("\n");
+		} else {
+		    GC_printf0("(unmapped)\n");
+		}
+		actual_index = free_list_index_of(hhdr);
+		if (-1 == actual_index) {
+		    GC_printf1("\t\tBlock not on free list %ld!!\n",
+				correct_index);
+		} else if (correct_index != actual_index) {
+		    GC_printf2("\t\tBlock on list %ld, should be on %ld!!\n",
+			       actual_index, correct_index);
+		}
+		p += hhdr -> hb_sz;
+	    } else {
+		GC_printf1("\tused for blocks of size 0x%lx bytes\n",
+			   (unsigned long)WORDS_TO_BYTES(hhdr -> hb_sz));
+		p += HBLKSIZE * OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz);
+	    }
+	}
+    }
+}
+
 # endif /* NO_DEBUGGING */
 
 /* Initialize hdr for a block containing the indicated size and 	*/
@@ -100,18 +208,265 @@ unsigned char flags;
     return(TRUE);
 }
 
-#ifdef EXACT_FIRST
-#   define LAST_TRIP 2
-#else
-#   define LAST_TRIP 1
-#endif
+#define FL_UNKNOWN -1
+/*
+ * Remove hhdr from the appropriate free list.
+ * We assume it is on the nth free list, or on the size
+ * appropriate free list if n is FL_UNKNOWN.
+ */
+void GC_remove_from_fl(hhdr, n)
+hdr * hhdr;
+int n;
+{
+    GC_ASSERT(((hhdr -> hb_sz) & (HBLKSIZE-1)) == 0);
+    if (hhdr -> hb_prev == 0) {
+        int index;
+	if (FL_UNKNOWN == n) {
+            index = GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz));
+	} else {
+	    index = n;
+	}
+	GC_ASSERT(HDR(GC_hblkfreelist[index]) == hhdr);
+	GC_hblkfreelist[index] = hhdr -> hb_next;
+    } else {
+	PHDR(hhdr) -> hb_next = hhdr -> hb_next;
+    }
+    if (0 != hhdr -> hb_next) {
+	GC_ASSERT(!IS_FORWARDING_ADDR_OR_NIL(NHDR(hhdr)));
+	NHDR(hhdr) -> hb_prev = hhdr -> hb_prev;
+    }
+}
+
+/*
+ * Return a pointer to the free block ending just before h, if any.
+ */
+struct hblk * GC_free_block_ending_at(h)
+struct hblk *h;
+{
+    struct hblk * p = h - 1;
+    hdr * phdr = HDR(p);
+
+    while (0 != phdr && IS_FORWARDING_ADDR_OR_NIL(phdr)) {
+	p = FORWARDED_ADDR(p,phdr);
+	phdr = HDR(p);
+    }
+    if (0 != phdr && HBLK_IS_FREE(phdr)) return p;
+    p = GC_prev_block(h - 1);
+    if (0 != p) {
+      phdr = HDR(p);
+      if (HBLK_IS_FREE(phdr) && (ptr_t)p + phdr -> hb_sz == (ptr_t)h) {
+	return p;
+      }
+    }
+    return 0;
+}
+
+/*
+ * Add hhdr to the appropriate free list.
+ * We maintain individual free lists sorted by address.
+ */
+void GC_add_to_fl(h, hhdr)
+struct hblk *h;
+hdr * hhdr;
+{
+    int index = GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz));
+    struct hblk *second = GC_hblkfreelist[index];
+#   ifdef GC_ASSERTIONS
+      struct hblk *next = (struct hblk *)((word)h + hhdr -> hb_sz);
+      hdr * nexthdr = HDR(next);
+      struct hblk *prev = GC_free_block_ending_at(h);
+      hdr * prevhdr = HDR(prev);
+      GC_ASSERT(nexthdr == 0 || !HBLK_IS_FREE(nexthdr) || !IS_MAPPED(nexthdr));
+      GC_ASSERT(prev == 0 || !HBLK_IS_FREE(prevhdr) || !IS_MAPPED(prevhdr));
+#   endif
+    GC_ASSERT(((hhdr -> hb_sz) & (HBLKSIZE-1)) == 0);
+    GC_hblkfreelist[index] = h;
+    hhdr -> hb_next = second;
+    hhdr -> hb_prev = 0;
+    if (0 != second) HDR(second) -> hb_prev = h;
+    GC_invalidate_map(hhdr);
+}
+
+#ifdef USE_MUNMAP
+
+/* Unmap blocks that haven't been recently touched.  This is the only way */
+/* way blocks are ever unmapped.					  */
+void GC_unmap_old(void)
+{
+    struct hblk * h;
+    hdr * hhdr;
+    word sz;
+    unsigned short last_rec, threshold;
+    int i;
+#   define UNMAP_THRESHOLD 6
+    
+    for (i = 0; i <= N_HBLK_FLS; ++i) {
+      for (h = GC_hblkfreelist[i]; 0 != h; h = hhdr -> hb_next) {
+        hhdr = HDR(h);
+	if (!IS_MAPPED(hhdr)) continue;
+	threshold = (unsigned short)(GC_gc_no - UNMAP_THRESHOLD);
+	last_rec = hhdr -> hb_last_reclaimed;
+	if (last_rec > GC_gc_no
+	    || last_rec < threshold && threshold < GC_gc_no
+				       /* not recently wrapped */) {
+          sz = hhdr -> hb_sz;
+	  GC_unmap((ptr_t)h, sz);
+	  hhdr -> hb_flags |= WAS_UNMAPPED;
+    	}
+      }
+    }  
+}
+
+/* Merge all unmapped blocks that are adjacent to other free		*/
+/* blocks.  This may involve remapping, since all blocks are either	*/
+/* fully mapped or fully unmapped.					*/
+void GC_merge_unmapped(void)
+{
+    struct hblk * h, *next;
+    hdr * hhdr, *nexthdr;
+    word size, nextsize;
+    int i;
+    
+    for (i = 0; i <= N_HBLK_FLS; ++i) {
+      h = GC_hblkfreelist[i];
+      while (h != 0) {
+	hhdr = HDR(h);
+	size = hhdr->hb_sz;
+	next = (struct hblk *)((word)h + size);
+	nexthdr = HDR(next);
+	/* Coalesce with successor, if possible */
+	  if (0 != nexthdr && HBLK_IS_FREE(nexthdr)) {
+	    nextsize = nexthdr -> hb_sz;
+	    if (IS_MAPPED(hhdr)) {
+	      GC_ASSERT(!IS_MAPPED(nexthdr));
+	      /* make both consistent, so that we can merge */
+	        if (size > nextsize) {
+		  GC_remap((ptr_t)next, nextsize);
+		} else {
+		  GC_unmap((ptr_t)h, size);
+		  hhdr -> hb_flags |= WAS_UNMAPPED;
+		}
+	    } else if (IS_MAPPED(nexthdr)) {
+	      GC_ASSERT(!IS_MAPPED(hhdr));
+	      if (size > nextsize) {
+		GC_unmap((ptr_t)next, nextsize);
+	      } else {
+		GC_remap((ptr_t)h, size);
+		hhdr -> hb_flags &= ~WAS_UNMAPPED;
+	      }
+	    } else {
+	      /* Unmap any gap in the middle */
+		GC_unmap_gap((ptr_t)h, size, (ptr_t)next, nexthdr -> hb_sz);
+	    }
+	    /* If they are both unmapped, we merge, but leave unmapped. */
+	    GC_remove_from_fl(hhdr, i);
+	    GC_remove_from_fl(nexthdr, FL_UNKNOWN);
+	    hhdr -> hb_sz += nexthdr -> hb_sz; 
+	    GC_remove_header(next);
+	    GC_add_to_fl(h, hhdr); 
+	    /* Start over at beginning of list */
+	    h = GC_hblkfreelist[i];
+	  } else /* not mergable with successor */ {
+	    h = hhdr -> hb_next;
+	  }
+      } /* while (h != 0) ... */
+    } /* for ... */
+}
+
+#endif /* USE_MUNMAP */
+
+/*
+ * Return a pointer to a block starting at h of length bytes.
+ * Memory for the block is mapped.
+ * Remove the block from its free list, and return the remainder (if any)
+ * to its appropriate free list.
+ * May fail by returning 0.
+ * The header for the returned block must be set up by the caller.
+ * If the return value is not 0, then hhdr is the header for it.
+ */
+struct hblk * GC_get_first_part(h, hhdr, bytes, index)
+struct hblk *h;
+hdr * hhdr;
+word bytes;
+int index;
+{
+    word total_size = hhdr -> hb_sz;
+    struct hblk * rest;
+    hdr * rest_hdr;
+
+    GC_ASSERT((total_size & (HBLKSIZE-1)) == 0);
+    GC_remove_from_fl(hhdr, index);
+    if (total_size == bytes) return h;
+    rest = (struct hblk *)((word)h + bytes);
+    if (!GC_install_header(rest)) return(0);
+    rest_hdr = HDR(rest);
+    rest_hdr -> hb_sz = total_size - bytes;
+    rest_hdr -> hb_flags = 0;
+#   ifdef GC_ASSERTIONS
+      // Mark h not free, to avoid assertion about adjacent free blocks.
+        hhdr -> hb_map = 0;
+#   endif
+    GC_add_to_fl(rest, rest_hdr);
+    return h;
+}
+
+/*
+ * H is a free block.  N points at an address inside it.
+ * A new header for n has already been set up.  Fix up h's header
+ * to reflect the fact that it is being split, move it to the
+ * appropriate free list.
+ * N replaces h in the original free list.
+ *
+ * Nhdr is not completely filled in, since it is about to allocated.
+ * It may in fact end up on the wrong free list for its size.
+ * (Hence adding it to a free list is silly.  But this path is hopefully
+ * rare enough that it doesn't matter.  The code is cleaner this way.)
+ */
+void GC_split_block(h, hhdr, n, nhdr, index)
+struct hblk *h;
+hdr * hhdr;
+struct hblk *n;
+hdr * nhdr;
+int index;	/* Index of free list */
+{
+    word total_size = hhdr -> hb_sz;
+    word h_size = (word)n - (word)h;
+    struct hblk *prev = hhdr -> hb_prev;
+    struct hblk *next = hhdr -> hb_next;
+
+    /* Replace h with n on its freelist */
+      nhdr -> hb_prev = prev;
+      nhdr -> hb_next = next;
+      nhdr -> hb_sz = total_size - h_size;
+      nhdr -> hb_flags = 0;
+      if (0 != prev) {
+	HDR(prev) -> hb_next = n;
+      } else {
+        GC_hblkfreelist[index] = n;
+      }
+      if (0 != next) {
+	HDR(next) -> hb_prev = n;
+      }
+#     ifdef GC_ASSERTIONS
+	nhdr -> hb_map = 0;	/* Don't fail test for consecutive	*/
+				/* free blocks in GC_add_to_fl.		*/
+#     endif
+#   ifdef USE_MUNMAP
+      hhdr -> hb_last_reclaimed = GC_gc_no;
+#   endif
+    hhdr -> hb_sz = h_size;
+    GC_add_to_fl(h, hhdr);
+    GC_invalidate_map(nhdr);
+}
 	
+struct hblk * GC_allochblk_nth();
+
 /*
  * Allocate (and return pointer to) a heap block
- *   for objects of size sz words.
+ *   for objects of size sz words, searching the nth free list.
  *
  * NOTE: We set obj_map field in header correctly.
- *       Caller is resposnsible for building an object freelist in block.
+ *       Caller is responsible for building an object freelist in block.
  *
  * We clear the block if it is destined for large objects, and if
  * kind requires that newly allocated objects be cleared.
@@ -122,44 +477,42 @@ word sz;
 int kind;
 unsigned char flags;  /* IGNORE_OFF_PAGE or 0 */
 {
-    register struct hblk *thishbp;
-    register hdr * thishdr;		/* Header corr. to thishbp */
+    int start_list = GC_hblk_fl_from_blocks(OBJ_SZ_TO_BLOCKS(sz));
+    int i;
+    for (i = start_list; i <= N_HBLK_FLS; ++i) {
+	struct hblk * result = GC_allochblk_nth(sz, kind, flags, i);
+	if (0 != result) return result;
+    }
+    return 0;
+}
+/*
+ * The same, but with search restricted to nth free list.
+ */
+struct hblk *
+GC_allochblk_nth(sz, kind, flags, n)
+word sz;
+int kind;
+unsigned char flags;  /* IGNORE_OFF_PAGE or 0 */
+int n;
+{
     register struct hblk *hbp;
     register hdr * hhdr;		/* Header corr. to hbp */
-    struct hblk *prevhbp;
-    register hdr * phdr;		/* Header corr. to prevhbp */
+    register struct hblk *thishbp;
+    register hdr * thishdr;		/* Header corr. to hbp */
     signed_word size_needed;    /* number of bytes in requested objects */
     signed_word size_avail;	/* bytes available in this block	*/
-    int trip_count = 0;
 
     size_needed = HBLKSIZE * OBJ_SZ_TO_BLOCKS(sz);
 
     /* search for a big enough block in free list */
-	hbp = GC_savhbp;
+	hbp = GC_hblkfreelist[n];
 	hhdr = HDR(hbp);
-	for(;;) {
-
-	    prevhbp = hbp;
-	    phdr = hhdr;
-	    hbp = (prevhbp == 0? GC_hblkfreelist : phdr->hb_next);
-	    hhdr = HDR(hbp);
-
-	    if( prevhbp == GC_savhbp) {
-		if (trip_count == LAST_TRIP) return(0);
-		++trip_count;
-	    }
-
-	    if( hbp == 0 ) continue;
-
+	for(; 0 != hbp; hbp = hhdr -> hb_next, hhdr = HDR(hbp)) {
 	    size_avail = hhdr->hb_sz;
-#	    ifdef EXACT_FIRST
-		if (trip_count <= 1 && size_avail != size_needed) continue;
-#	    endif
 	    if (size_avail < size_needed) continue;
 #	    ifdef PRESERVE_LAST
 		if (size_avail != size_needed
-		    && !GC_incremental
-		    && GC_in_last_heap_sect(hbp) && GC_should_collect()) {
+		    && !GC_incremental && GC_should_collect()) {
 		    continue;
 		} 
 #	    endif
@@ -170,13 +523,14 @@ unsigned char flags;  /* IGNORE_OFF_PAGE or 0 */
 	      signed_word next_size;
 	      
 	      thishbp = hhdr -> hb_next;
-	      if (thishbp == 0) thishbp = GC_hblkfreelist; 
-	      thishdr = HDR(thishbp);
-	      next_size = (signed_word)(thishdr -> hb_sz);
-	      if (next_size < size_avail
+	      if (thishbp != 0) {
+	        thishdr = HDR(thishbp);
+	        next_size = (signed_word)(thishdr -> hb_sz);
+	        if (next_size < size_avail
 	          && next_size >= size_needed
 	          && !GC_is_black_listed(thishbp, (word)size_needed)) {
 	          continue;
+	        }
 	      }
 	    }
 	    if ( !IS_UNCOLLECTABLE(kind) &&
@@ -198,19 +552,21 @@ unsigned char flags;  /* IGNORE_OFF_PAGE or 0 */
 	      thishbp = lasthbp;
 	      if (size_avail >= size_needed) {
 	        if (thishbp != hbp && GC_install_header(thishbp)) {
+		  /* Make sure it's mapped before we mangle it. */
+#		    ifdef USE_MUNMAP
+		      if (!IS_MAPPED(hhdr)) {
+		        GC_remap((ptr_t)hbp, size_avail);
+		        hhdr -> hb_flags &= ~WAS_UNMAPPED;
+		      }
+#		    endif
 	          /* Split the block at thishbp */
 	              thishdr = HDR(thishbp);
-	              /* GC_invalidate_map not needed, since we will	*/
-	              /* allocate this block.				*/
-		      thishdr -> hb_next = hhdr -> hb_next;
-		      thishdr -> hb_sz = size_avail;
-		      hhdr -> hb_sz = (ptr_t)thishbp - (ptr_t)hbp;
-		      hhdr -> hb_next = thishbp;
+		      GC_split_block(hbp, hhdr, thishbp, thishdr, n);
 		  /* Advance to thishbp */
-		      prevhbp = hbp;
-		      phdr = hhdr;
 		      hbp = thishbp;
 		      hhdr = thishdr;
+		      /* We must now allocate thishbp, since it may	*/
+		      /* be on the wrong free list.			*/
 		}
 	      } else if (size_needed > (signed_word)BL_LIMIT
 	                 && orig_avail - size_needed
@@ -218,12 +574,10 @@ unsigned char flags;  /* IGNORE_OFF_PAGE or 0 */
 	        /* Punt, since anything else risks unreasonable heap growth. */
 	        WARN("Needed to allocate blacklisted block at 0x%lx\n",
 		     (word)hbp);
-	        thishbp = hbp;
 	        size_avail = orig_avail;
-	      } else if (size_avail == 0
-	      		 && size_needed == HBLKSIZE
-	      		 && prevhbp != 0) {
-#		ifndef FIND_LEAK
+	      } else if (size_avail == 0 && size_needed == HBLKSIZE
+			 && IS_MAPPED(hhdr)) {
+		if (!GC_find_leak) {
 	      	  static unsigned count = 0;
 	      	  
 	      	  /* The block is completely blacklisted.  We need 	*/
@@ -235,11 +589,14 @@ unsigned char flags;  /* IGNORE_OFF_PAGE or 0 */
 	            /* Allocate and drop the block in small chunks, to	*/
 	            /* maximize the chance that we will recover some	*/
 	            /* later.						*/
-	              struct hblk * limit = hbp + (hhdr->hb_sz/HBLKSIZE);
+		      word total_size = hhdr -> hb_sz;
+	              struct hblk * limit = hbp + divHBLKSZ(total_size);
 	              struct hblk * h;
+		      struct hblk * prev = hhdr -> hb_prev;
 	              
-		      GC_words_wasted += hhdr->hb_sz;
-	              phdr -> hb_next = hhdr -> hb_next;
+		      GC_words_wasted += total_size;
+		      GC_large_free_bytes -= total_size;
+		      GC_remove_from_fl(hhdr, n);
 	              for (h = hbp; h < limit; h++) {
 	                if (h == hbp || GC_install_header(h)) {
 	                  hhdr = HDR(h);
@@ -248,69 +605,53 @@ unsigned char flags;  /* IGNORE_OFF_PAGE or 0 */
 	              		  BYTES_TO_WORDS(HBLKSIZE - HDR_BYTES),
 	              		  PTRFREE, 0); /* Cant fail */
 	              	  if (GC_debugging_started) {
-	              	    BZERO(hbp + HDR_BYTES, HBLKSIZE - HDR_BYTES);
+	              	    BZERO(h + HDR_BYTES, HBLKSIZE - HDR_BYTES);
 	              	  }
 	                }
 	              }
 	            /* Restore hbp to point at free block */
-	              if (GC_savhbp == hbp) GC_savhbp = prevhbp;
-	              hbp = prevhbp;
-	              hhdr = phdr;
-	              if (hbp == GC_savhbp) --trip_count;
+		      hbp = prev;
+		      if (0 == hbp) {
+			return GC_allochblk_nth(sz, kind, flags, n);
+		      }
+	   	      hhdr = HDR(hbp);
 	          }
-#		endif
+		}
 	      }
 	    }
 	    if( size_avail >= size_needed ) {
-		/* found a big enough block       */
-		/* let thishbp --> the block      */
-		/* set prevhbp, hbp to bracket it */
-		    thishbp = hbp;
-		    thishdr = hhdr;
-		    if( size_avail == size_needed ) {
-			hbp = hhdr->hb_next;
-			hhdr = HDR(hbp);
-		    } else {
-			hbp = (struct hblk *)
-			    (((word)thishbp) + size_needed);
-			if (!GC_install_header(hbp)) {
-			    hbp = thishbp;
-			    continue;
-			}
-			hhdr = HDR(hbp);
-			GC_invalidate_map(hhdr);
-			hhdr->hb_next = thishdr->hb_next;
-			hhdr->hb_sz = size_avail - size_needed;
-		    }
-		/* remove *thishbp from hblk freelist */
-		    if( prevhbp == 0 ) {
-			GC_hblkfreelist = hbp;
-		    } else {
-			phdr->hb_next = hbp;
-		    }
-		/* save current list search position */
-		    GC_savhbp = hbp;
+#		ifdef USE_MUNMAP
+		  if (!IS_MAPPED(hhdr)) {
+		    GC_remap((ptr_t)hbp, size_avail);
+		    hhdr -> hb_flags &= ~WAS_UNMAPPED;
+		  }
+#	        endif
+		/* hbp may be on the wrong freelist; the parameter n	*/
+		/* is important.					*/
+		hbp = GC_get_first_part(hbp, hhdr, size_needed, n);
 		break;
 	    }
 	}
+
+    if (0 == hbp) return 0;
 	
     /* Notify virtual dirty bit implementation that we are about to write. */
-    	GC_write_hint(thishbp);
+    	GC_write_hint(hbp);
     
     /* Add it to map of valid blocks */
-    	if (!GC_install_counts(thishbp, (word)size_needed)) return(0);
+    	if (!GC_install_counts(hbp, (word)size_needed)) return(0);
     	/* This leaks memory under very rare conditions. */
     		
     /* Set up header */
-        if (!setup_header(thishdr, sz, kind, flags)) {
-            GC_remove_counts(thishbp, (word)size_needed);
+        if (!setup_header(hhdr, sz, kind, flags)) {
+            GC_remove_counts(hbp, (word)size_needed);
             return(0); /* ditto */
         }
         
     /* Clear block if necessary */
 	if (GC_debugging_started
 	    || sz > MAXOBJSZ && GC_obj_kinds[kind].ok_init) {
-	    BZERO(thishbp + HDR_BYTES,  size_needed - HDR_BYTES);
+	    BZERO(hbp + HDR_BYTES,  size_needed - HDR_BYTES);
 	}
 
     /* We just successfully allocated a block.  Restart count of	*/
@@ -320,8 +661,11 @@ unsigned char flags;  /* IGNORE_OFF_PAGE or 0 */
 	
 	GC_fail_count = 0;
     }
+
+    GC_large_free_bytes -= size_needed;
     
-    return( thishbp );
+    GC_ASSERT(IS_MAPPED(hhdr));
+    return( hbp );
 }
  
 struct hblk * GC_freehblk_ptr = 0;  /* Search position hint for GC_freehblk */
@@ -334,75 +678,50 @@ struct hblk * GC_freehblk_ptr = 0;  /* Search position hint for GC_freehblk */
  * All mark words are assumed to be cleared.
  */
 void
-GC_freehblk(p)
-register struct hblk *p;
+GC_freehblk(hbp)
+struct hblk *hbp;
 {
-register hdr *phdr;	/* Header corresponding to p */
-register struct hblk *hbp, *prevhbp;
-register hdr *hhdr, *prevhdr;
-register signed_word size;
+struct hblk *next, *prev;
+hdr *hhdr, *prevhdr, *nexthdr;
+signed_word size;
 
-    /* GC_savhbp may become invalid due to coalescing.  Clear it. */
-	GC_savhbp = (struct hblk *)0;
 
-    phdr = HDR(p);
-    size = phdr->hb_sz;
-    size = HBLKSIZE * OBJ_SZ_TO_BLOCKS(size);
-    GC_remove_counts(p, (word)size);
-    phdr->hb_sz = size;
-    GC_invalidate_map(phdr);
-    prevhbp = 0;
-    
-    /* The following optimization was suggested by David Detlefs.	*/
-    /* Note that the header cannot be NIL, since there cannot be an	*/
-    /* intervening  call to GC_freehblk without resetting		*/
-    /* GC_freehblk_ptr.							*/
-    if (GC_freehblk_ptr != 0 &&
-    	HDR(GC_freehblk_ptr)->hb_map == GC_invalid_map &&
-    	(ptr_t)GC_freehblk_ptr < (ptr_t)p) {
-      hbp = GC_freehblk_ptr;
-    } else {
-      hbp = GC_hblkfreelist;
-    };
     hhdr = HDR(hbp);
-
-    while( (hbp != 0) && (hbp < p) ) {
-	prevhbp = hbp;
-	prevhdr = hhdr;
-	hbp = hhdr->hb_next;
-	hhdr = HDR(hbp);
-    }
-    GC_freehblk_ptr = prevhbp;
+    size = hhdr->hb_sz;
+    size = HBLKSIZE * OBJ_SZ_TO_BLOCKS(size);
+    GC_remove_counts(hbp, (word)size);
+    hhdr->hb_sz = size;
     
     /* Check for duplicate deallocation in the easy case */
-      if (hbp != 0 && (ptr_t)p + size > (ptr_t)hbp
-        || prevhbp != 0 && (ptr_t)prevhbp + prevhdr->hb_sz > (ptr_t)p) {
+      if (HBLK_IS_FREE(hhdr)) {
         GC_printf1("Duplicate large block deallocation of 0x%lx\n",
-        	   (unsigned long) p);
-        GC_printf2("Surrounding free blocks are 0x%lx and 0x%lx\n",
-           	   (unsigned long) prevhbp, (unsigned long) hbp);
+        	   (unsigned long) hbp);
       }
 
+    GC_ASSERT(IS_MAPPED(hhdr));
+    GC_invalidate_map(hhdr);
+    next = (struct hblk *)((word)hbp + size);
+    nexthdr = HDR(next);
+    prev = GC_free_block_ending_at(hbp);
     /* Coalesce with successor, if possible */
-      if( (((word)p)+size) == ((word)hbp) ) {
-	phdr->hb_next = hhdr->hb_next;
-	phdr->hb_sz += hhdr->hb_sz;
-	GC_remove_header(hbp);
-      } else {
-	phdr->hb_next = hbp;
+      if(0 != nexthdr && HBLK_IS_FREE(nexthdr) && IS_MAPPED(nexthdr)) {
+	GC_remove_from_fl(nexthdr, FL_UNKNOWN);
+	hhdr -> hb_sz += nexthdr -> hb_sz; 
+	GC_remove_header(next);
+      }
+    /* Coalesce with predecessor, if possible. */
+      if (0 != prev) {
+	prevhdr = HDR(prev);
+	if (IS_MAPPED(prevhdr)) {
+	  GC_remove_from_fl(prevhdr, FL_UNKNOWN);
+	  prevhdr -> hb_sz += hhdr -> hb_sz;
+	  GC_remove_header(hbp);
+	  hbp = prev;
+	  hhdr = prevhdr;
+	}
       }
 
-    
-    if( prevhbp == 0 ) {
-	GC_hblkfreelist = p;
-    } else if( (((word)prevhbp) + prevhdr->hb_sz)
-      	       == ((word)p) ) {
-      /* Coalesce with predecessor */
-	prevhdr->hb_next = phdr->hb_next;
-	prevhdr->hb_sz += phdr->hb_sz;
-	GC_remove_header(p);
-    } else {
-	prevhdr->hb_next = p;
-    }
+    GC_large_free_bytes += size;
+    GC_add_to_fl(hbp, hhdr);    
 }