X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Frts%2FMBlock.h;h=07c40a05de6b7384b181a1fbb37f887c5c676629;hb=153b9cb9b11e05c4edb1b6bc0a7b972660e41f70;hp=1615f7048cb2bc667b06a674320f35cdb6bc10a6;hpb=7f309f1c021e7583f724cce599ce2dd3c439361b;p=ghc-hetmet.git

diff --git a/ghc/rts/MBlock.h b/ghc/rts/MBlock.h
index 1615f70..07c40a0 100644
--- a/ghc/rts/MBlock.h
+++ b/ghc/rts/MBlock.h
@@ -1,5 +1,4 @@
 /* -----------------------------------------------------------------------------
- * $Id: MBlock.h,v 1.4 1999/02/05 16:02:45 simonm Exp $
  *
  * (c) The GHC Team, 1998-1999
  *
@@ -7,7 +6,84 @@
  *
  * ---------------------------------------------------------------------------*/
 
-extern lnat mblocks_allocated;
+#ifndef __MBLOCK_H__
+#define __MBLOCK_H__
+
+extern lnat RTS_VAR(mblocks_allocated);
 
 extern void * getMBlock(void);
 extern void * getMBlocks(nat n);
+
+#if osf3_HOST_OS
+/* ToDo: Perhaps by adjusting this value we can make linking without
+ * -static work (i.e., not generate a core-dumping executable)? */
+#if SIZEOF_VOID_P == 8
+#define HEAP_BASE 0x180000000L
+#else
+#error I have no idea where to begin the heap on a non-64-bit osf3 machine.
+#endif
+
+#else
+
+// we're using the generic method
+#define HEAP_BASE 0
+
+#endif
+
+/* -----------------------------------------------------------------------------
+   The HEAP_ALLOCED() test.
+
+   HEAP_ALLOCED is called FOR EVERY SINGLE CLOSURE during GC.
+   It needs to be FAST.
+
+   Implementation of HEAP_ALLOCED
+   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+   Since heap is allocated in chunks of megablocks (MBLOCK_SIZE), we
+   can just use a table to record which megablocks in the address
+   space belong to the heap.  On a 32-bit machine, with 1Mb
+   megablocks, using 8 bits for each entry in the table, the table
+   requires 4k.  Lookups during GC will be fast, because the table
+   will be quickly cached (indeed, performance measurements showed no
+   measurable difference between doing the table lookup and using a
+   constant comparison).
+
+   On 64-bit machines, we cache one 12-bit block map that describes
+   4096 megablocks or 4GB of memory. If HEAP_ALLOCED is called for
+   an address that is not in the cache, it calls slowIsHeapAlloced
+   (see MBlock.c) which will find the block map for the 4GB block in
+   question.
+   -------------------------------------------------------------------------- */
+
+#if SIZEOF_VOID_P == 4
+extern StgWord8 mblock_map[];
+
+/* On a 32-bit machine a 4KB table is always sufficient */
+# define MBLOCK_MAP_SIZE	4096
+# define MBLOCK_MAP_ENTRY(p)	((StgWord)(p) >> MBLOCK_SHIFT)
+# define HEAP_ALLOCED(p)	mblock_map[MBLOCK_MAP_ENTRY(p)]
+
+#elif SIZEOF_VOID_P == 8
+
+# define MBLOCK_MAP_SIZE	4096
+# define MBLOCK_MAP_ENTRY(p)	(((StgWord)(p) & 0xffffffff) >> MBLOCK_SHIFT)
+
+typedef struct {
+    StgWord32	addrHigh32;
+    StgWord8	mblocks[MBLOCK_MAP_SIZE];
+} MBlockMap;
+
+extern MBlockMap *mblock_cache;
+
+StgBool slowIsHeapAlloced(void *p);
+
+# define HEAP_ALLOCED(p)  					\
+	( ((((StgWord)(p)) >> 32) == mblock_cache->addrHigh32)	\
+	? mblock_cache->mblocks[MBLOCK_MAP_ENTRY(p)]		\
+	: slowIsHeapAlloced(p) )
+
+#else
+# error HEAP_ALLOCED not defined
+#endif
+
+#endif // __MBLOCK_H__