/* ----------------------------------------------------------------------------
- * $Id: Closures.h,v 1.29 2001/11/22 14:25:11 simonmar Exp $
*
- * (c) The GHC Team, 1998-1999
+ * (c) The GHC Team, 1998-2004
*
* Closures
*
typedef struct {
CostCentreStack *ccs;
union {
- RetainerSet *rs; // Retainer Set
+ struct _RetainerSet *rs; // Retainer Set
StgWord ldvw; // Lag/Drag/Void Word
} hp;
} StgProfHeader;
/* -----------------------------------------------------------------------------
- The parallel header
- -------------------------------------------------------------------------- */
-
-typedef struct {
- /* StgWord ga; */ /* nope! global addresses are managed via a hash table */
-} StgParHeader;
-
-/* -----------------------------------------------------------------------------
The GranSim header
-------------------------------------------------------------------------- */
} StgGranHeader;
/* -----------------------------------------------------------------------------
- The ticky-ticky header
-
- Comment from old Ticky.h:
-
- This is used to record if a closure has been updated but not yet
- entered. It is set when the closure is updated and cleared when
- subsequently entered.
-
- NB: It is {\em not} an ``entry count'', it is an
- ``entries-after-update count.''
-
- The commoning up of @CONST@, @CHARLIKE@ and @INTLIKE@ closures is
- turned off(?) if this is required. This has only been done for 2s
- collection. It is done using a nasty hack which defines the
- @_Evacuate@ and @_Scavenge@ code for @CONST@, @CHARLIKE@ and @INTLIKE@
- info tables to be @_Evacuate_1@ and @_Scavenge_1_0@.
- -------------------------------------------------------------------------- */
-
-typedef struct {
- /* old: W_ updated; */
-} StgTickyHeader;
-
-/* -----------------------------------------------------------------------------
The full fixed-size closure header
The size of the fixed header is the sum of the optional parts plus a single
#ifdef PROFILING
StgProfHeader prof;
#endif
-#ifdef PAR
- StgParHeader par;
-#endif
#ifdef GRAN
StgGranHeader gran;
#endif
-#ifdef TICKY_TICKY
- StgTickyHeader ticky;
-#endif
} StgHeader;
-#define FIXED_HS (sizeof(StgHeader))
-
/* -----------------------------------------------------------------------------
Closure Types
typedef struct {
StgHeader header;
- StgWord n_args;
- StgClosure *fun;
+ StgHalfWord arity; /* zero if it is an AP */
+ StgHalfWord n_args;
+ StgClosure *fun; /* really points to a fun */
StgClosure *payload[FLEXIBLE_ARRAY];
} StgPAP;
+// AP closures have the same layout, for convenience
+typedef StgPAP StgAP;
+
typedef struct {
StgHeader header;
- StgWord n_args;
+ StgWord size; // number of words in payload
StgClosure *fun;
- StgClosure *payload[FLEXIBLE_ARRAY];
-} StgAP_UPD;
+ StgClosure *payload[FLEXIBLE_ARRAY]; // contains a chunk of *stack*
+} StgAP_STACK;
typedef struct {
StgHeader header;
StgMutClosure *mut_link;
} StgMutVar;
-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 */
-} StgBCO;
-
-/*
- A collective typedef for all linkable stack frames i.e.
- StgUpdateFrame, StgSeqFrame, StgCatchFrame
-*/
-typedef struct _StgFrame {
- StgHeader header;
- struct _StgFrame *link;
-} StgFrame;
-
typedef struct _StgUpdateFrame {
StgHeader header;
- struct _StgUpdateFrame *link;
StgClosure *updatee;
} StgUpdateFrame;
typedef struct {
StgHeader header;
- struct _StgUpdateFrame *link;
-} StgSeqFrame;
-
-typedef struct {
- StgHeader header;
- struct _StgUpdateFrame *link;
StgInt exceptions_blocked;
StgClosure *handler;
} StgCatchFrame;
struct _StgWeak *link;
} StgDeadWeak;
-/* Dynamic stack frames - these have a liveness mask in the object
- * itself, rather than in the info table. Useful for generic heap
- * check code.
+/* Byte code objects. These are fixed size objects with pointers to
+ * four arrays, designed so that a BCO can be easily "re-linked" to
+ * other BCOs, to facilitate GHC's intelligent recompilation. The
+ * array of instructions is static and not re-generated when the BCO
+ * is re-linked, but the other 3 arrays will be regenerated.
+ *
+ * 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 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
+ StgHalfWord arity; // arity of this BCO
+ StgHalfWord size; // size of this BCO (in words)
+ StgWord bitmap[FLEXIBLE_ARRAY]; // an StgLargeBitmap
+} StgBCO;
+
+#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))
+
+/* -----------------------------------------------------------------------------
+ Dynamic stack frames for generic heap checks.
+
+ These generic heap checks are slow, but have the advantage of being
+ usable in a variety of situations.
+
+ The one restriction is that any relevant SRTs must already be pointed
+ to from the stack. The return address doesn't need to have an info
+ table attached: hence it can be any old code pointer.
+
+ The liveness mask contains a 1 at bit n, if register Rn contains a
+ non-pointer. The contents of all 8 vanilla registers are always saved
+ on the stack; the liveness mask tells the GC which ones contain
+ pointers.
+
+ Good places to use a generic heap check:
+
+ - case alternatives (the return address with an SRT is already
+ on the stack).
+
+ - primitives (no SRT required).
+
+ The stack frame layout for a RET_DYN is like this:
+
+ some pointers |-- RET_DYN_PTRS(liveness) words
+ some nonpointers |-- RET_DYN_NONPTRS(liveness) words
+
+ L1 \
+ D1-2 |-- RET_DYN_NONPTR_REGS_SIZE words
+ F1-4 /
+
+ R1-8 |-- RET_DYN_BITMAP_SIZE words
+
+ return address \
+ liveness mask |-- StgRetDyn structure
+ stg_gen_chk_info /
+
+ we assume that the size of a double is always 2 pointers (wasting a
+ word when it is only one pointer, but avoiding lots of #ifdefs).
+
+ See Liveness.h for the macros (RET_DYN_PTRS() etc.).
+
+ NOTE: if you change the layout of RET_DYN stack frames, then you
+ might also need to adjust the value of RESERVED_STACK_WORDS in
+ Constants.h.
+ -------------------------------------------------------------------------- */
+
typedef struct {
- const struct _StgInfoTable* info;
- StgWord liveness;
- StgWord ret_addr;
- StgWord payload[FLEXIBLE_ARRAY];
+ const struct _StgInfoTable* info;
+ StgWord liveness;
+ StgWord ret_addr;
+ StgClosure * payload[FLEXIBLE_ARRAY];
} StgRetDyn;
+/* A function return stack frame: used when saving the state for a
+ * garbage collection at a function entry point. The function
+ * arguments are on the stack, and we also save the function (its
+ * info table describes the pointerhood of the arguments).
+ *
+ * The stack frame size is also cached in the frame for convenience.
+ */
+typedef struct {
+ const struct _StgInfoTable* info;
+ StgWord size;
+ StgClosure * fun;
+ StgClosure * payload[FLEXIBLE_ARRAY];
+} StgRetFun;
+
/* Concurrent communication objects */
typedef struct {
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