[project @ 2003-06-27 18:28:31 by sof]

[ghc-hetmet.git] / ghc / rts / MBlock.h

diff --git a/ghc/rts/MBlock.h b/ghc/rts/MBlock.h
index 52467e5..c369416 100644 (file)
--- a/ghc/rts/MBlock.h
+++ b/ghc/rts/MBlock.h
@@ -1,5 +1,5 @@
 /* -----------------------------------------------------------------------------
- * $Id: MBlock.h,v 1.5 1999/03/03 19:04:57 sof Exp $
+ * $Id: MBlock.h,v 1.16 2002/11/22 06:54:05 matthewc Exp $
  *
  * (c) The GHC Team, 1998-1999
  *
@@ -7,11 +7,76 @@
  *
  * ---------------------------------------------------------------------------*/
 
+#ifndef __MBLOCK_H__
+#define __MBLOCK_H__
 extern lnat mblocks_allocated;
 
-#ifdef HAVE_WIN32_DLL_SUPPORT
-extern int is_heap_alloced(const void* p);
-#endif
-
 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).
+   -------------------------------------------------------------------------- */
+
+extern StgWord8 mblock_map[];
+
+#if SIZEOF_VOID_P == 4
+/* 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)]
+# define MARK_HEAP_ALLOCED(p)  (mblock_map[MBLOCK_MAP_ENTRY(p)] = 1)
+
+#elif defined(ia64_TARGET_ARCH)
+/* Instead of trying to cover the whole 64-bit address space (which would
+ * require a better data structure), we assume that mmap allocates mappings
+ * from the bottom of region 1, and track some portion of address space from
+ * there upwards (currently 4GB). */
+# define MBLOCK_MAP_SIZE       4096
+# define MBLOCK_MAP_ENTRY(p)   (((StgWord)(p) - (1UL << 61)) >> MBLOCK_SHIFT)
+# define HEAP_ALLOCED(p)       ((MBLOCK_MAP_ENTRY(p) < MBLOCK_MAP_SIZE) \
+                                       && mblock_map[MBLOCK_MAP_ENTRY(p)])
+# define MARK_HEAP_ALLOCED(p)  ((MBLOCK_MAP_ENTRY(p) < MBLOCK_MAP_SIZE) \
+                                       && (mblock_map[MBLOCK_MAP_ENTRY(p)] = 1))
+
+#elif defined(TEXT_BEFORE_HEAP)
+/* Fall back to old method - assume heap above HEAP_BASE */
+# define HEAP_ALLOCED(p)       ((StgPtr)(p) >= (StgPtr)(HEAP_BASE))
+# define MARK_HEAP_ALLOCED(p)  do {} while(0)
+
+#else
+# error HEAP_ALLOCED not defined
+#endif
+
+#endif // __MBLOCK_H__