/* ----------------------------------------------------------------------------
- * $Id: Closures.h,v 1.32 2002/12/11 15:36:37 simonmar Exp $
+ * $Id: Closures.h,v 1.33 2003/03/24 14:46:53 simonmar Exp $
*
* (c) The GHC Team, 1998-1999
*
* A BCO represents either a function or a stack frame. In each case,
* it needs a bitmap to describe to the garbage collector the
* pointerhood of its arguments/free variables respectively, and in
- * the case of a function it also needs an arity. These pieces of
- * information are stored at the beginning of the instruction array.
+ * the case of a function it also needs an arity. These are stored
+ * directly in the BCO, rather than in the instrs array, for two
+ * reasons:
+ * (a) speed: we need to get at the bitmap info quickly when
+ * the GC is examining APs and PAPs that point to this BCO
+ * (b) a subtle interaction with the compacting GC. In compacting
+ * GC, the info that describes the size/layout of a closure
+ * cannot be in an object more than one level of indirection
+ * away from the current object, because of the order in
+ * which pointers are updated to point to their new locations.
*/
typedef struct {
StgHeader header;
- StgArrWords *instrs; /* a pointer to an ArrWords */
- StgArrWords *literals; /* a pointer to an ArrWords */
- StgMutArrPtrs *ptrs; /* a pointer to a MutArrPtrs */
- StgArrWords *itbls; /* a pointer to an ArrWords */
+ StgArrWords *instrs; // a pointer to an ArrWords
+ StgArrWords *literals; // a pointer to an ArrWords
+ StgMutArrPtrs *ptrs; // a pointer to a MutArrPtrs
+ StgArrWords *itbls; // a pointer to an ArrWords
+ StgHalfWord arity; // arity of this BCO
+ StgHalfWord size; // size of this BCO (in words)
+ StgWord bitmap[FLEXIBLE_ARRAY]; // an StgLargeBitmap
} StgBCO;
-typedef struct {
- StgWord arity;
- StgWord bitmap[FLEXIBLE_ARRAY]; // really an StgLargeBitmap
-} StgBCOInfo;
-
-#define BCO_INFO(bco) ((StgBCOInfo *)(((StgBCO *)(bco))->instrs->payload))
-#define BCO_ARITY(bco) (BCO_INFO(bco)->arity)
-#define BCO_BITMAP(bco) ((StgLargeBitmap *)BCO_INFO(bco)->bitmap)
+#define BCO_BITMAP(bco) ((StgLargeBitmap *)((StgBCO *)(bco))->bitmap)
#define BCO_BITMAP_SIZE(bco) (BCO_BITMAP(bco)->size)
#define BCO_BITMAP_BITS(bco) (BCO_BITMAP(bco)->bitmap)
#define BCO_BITMAP_SIZEW(bco) ((BCO_BITMAP_SIZE(bco) + BITS_IN(StgWord) - 1) \
/ BITS_IN(StgWord))
-#define BCO_INSTRS(bco) ((StgWord16 *)(BCO_BITMAP_BITS(bco) + \
- BCO_BITMAP_SIZEW(bco)))
/* Dynamic stack frames - these have a liveness mask in the object
* itself, rather than in the info table. Useful for generic heap