X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Frts%2FMBlock.h;h=8d2a9792bed5b11df06d6b9984b1210190d5d40a;hb=61ccfec175e1f51b2c89559faf91d9bee0b3b601;hp=094c4fe393db495a965e9c50ac2b1ab9a66205b9;hpb=438596897ebbe25a07e1c82085cfbc5bdb00f09e;p=ghc-hetmet.git

diff --git a/ghc/rts/MBlock.h b/ghc/rts/MBlock.h
index 094c4fe..8d2a979 100644
--- a/ghc/rts/MBlock.h
+++ b/ghc/rts/MBlock.h
@@ -1,9 +1,89 @@
 /* -----------------------------------------------------------------------------
- * $Id: MBlock.h,v 1.2 1998/12/02 13:28:30 simonm Exp $
+ *
+ * (c) The GHC Team, 1998-1999
  *
  * MegaBlock Allocator interface.
  *
  * ---------------------------------------------------------------------------*/
 
+#ifndef __MBLOCK_H__
+#define __MBLOCK_H__
+
+extern lnat RTS_VAR(mblocks_allocated);
+
 extern void * getMBlock(void);
 extern void * getMBlocks(nat n);
+
+#if osf3_TARGET_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__