1 /* ----------------------------------------------------------------------------
3 * (c) The GHC Team, 1998-2004
7 * -------------------------------------------------------------------------- */
13 * The Layout of a closure header depends on which kind of system we're
14 * compiling for: profiling, parallel, ticky, etc.
17 /* -----------------------------------------------------------------------------
19 -------------------------------------------------------------------------- */
24 struct _RetainerSet *rs; /* Retainer Set */
25 StgWord ldvw; /* Lag/Drag/Void Word */
29 /* -----------------------------------------------------------------------------
31 -------------------------------------------------------------------------- */
34 StgWord procs; /* bitmask indicating on which PEs this closure resides */
37 /* -----------------------------------------------------------------------------
40 A thunk has a padding word to take the updated value. This is so
41 that the update doesn't overwrite the payload, so we can avoid
42 needing to lock the thunk during entry and update.
44 Note: this doesn't apply to THUNK_STATICs, which have no payload.
46 Note: we leave this padding word in all ways, rather than just SMP,
47 so that we don't have to recompile all our libraries for SMP.
48 -------------------------------------------------------------------------- */
54 /* -----------------------------------------------------------------------------
55 The full fixed-size closure header
57 The size of the fixed header is the sum of the optional parts plus a single
58 word for the entry code pointer.
59 -------------------------------------------------------------------------- */
62 const struct _StgInfoTable* info;
72 const struct _StgInfoTable* info;
79 StgSMPThunkHeader smp;
82 #define THUNK_EXTRA_HEADER_W (sizeofW(StgThunkHeader)-sizeofW(StgHeader))
84 /* -----------------------------------------------------------------------------
87 For any given closure type (defined in InfoTables.h), there is a
88 corresponding structure defined below. The name of the structure
89 is obtained by concatenating the closure type with '_closure'
90 -------------------------------------------------------------------------- */
92 /* All closures follow the generic format */
96 struct StgClosure_ *payload[FLEXIBLE_ARRAY];
100 StgThunkHeader header;
101 struct StgClosure_ *payload[FLEXIBLE_ARRAY];
105 StgThunkHeader header;
106 StgClosure *selectee;
111 StgHalfWord arity; /* zero if it is an AP */
113 StgClosure *fun; /* really points to a fun */
114 StgClosure *payload[FLEXIBLE_ARRAY];
118 StgThunkHeader header;
119 StgHalfWord arity; /* zero if it is an AP */
121 StgClosure *fun; /* really points to a fun */
122 StgClosure *payload[FLEXIBLE_ARRAY];
126 StgThunkHeader header;
127 StgWord size; /* number of words in payload */
129 StgClosure *payload[FLEXIBLE_ARRAY]; /* contains a chunk of *stack* */
134 StgClosure *indirectee;
139 StgClosure *indirectee;
140 StgClosure *static_link;
141 struct _StgInfoTable *saved_info;
147 StgWord payload[FLEXIBLE_ARRAY];
153 StgClosure *payload[FLEXIBLE_ARRAY];
161 typedef struct _StgUpdateFrame {
168 StgInt exceptions_blocked;
184 } StgIntCharlikeClosure;
186 /* statically allocated */
191 typedef struct _StgStableName {
196 typedef struct _StgWeak { /* Weak v */
199 StgClosure *value; /* v */
200 StgClosure *finalizer;
201 struct _StgWeak *link;
204 typedef struct _StgDeadWeak { /* Weak v */
206 struct _StgWeak *link;
209 /* Byte code objects. These are fixed size objects with pointers to
210 * four arrays, designed so that a BCO can be easily "re-linked" to
211 * other BCOs, to facilitate GHC's intelligent recompilation. The
212 * array of instructions is static and not re-generated when the BCO
213 * is re-linked, but the other 3 arrays will be regenerated.
215 * A BCO represents either a function or a stack frame. In each case,
216 * it needs a bitmap to describe to the garbage collector the
217 * pointerhood of its arguments/free variables respectively, and in
218 * the case of a function it also needs an arity. These are stored
219 * directly in the BCO, rather than in the instrs array, for two
221 * (a) speed: we need to get at the bitmap info quickly when
222 * the GC is examining APs and PAPs that point to this BCO
223 * (b) a subtle interaction with the compacting GC. In compacting
224 * GC, the info that describes the size/layout of a closure
225 * cannot be in an object more than one level of indirection
226 * away from the current object, because of the order in
227 * which pointers are updated to point to their new locations.
232 StgArrWords *instrs; /* a pointer to an ArrWords */
233 StgArrWords *literals; /* a pointer to an ArrWords */
234 StgMutArrPtrs *ptrs; /* a pointer to a MutArrPtrs */
235 StgArrWords *itbls; /* a pointer to an ArrWords */
236 StgHalfWord arity; /* arity of this BCO */
237 StgHalfWord size; /* size of this BCO (in words) */
238 StgWord bitmap[FLEXIBLE_ARRAY]; /* an StgLargeBitmap */
241 #define BCO_BITMAP(bco) ((StgLargeBitmap *)((StgBCO *)(bco))->bitmap)
242 #define BCO_BITMAP_SIZE(bco) (BCO_BITMAP(bco)->size)
243 #define BCO_BITMAP_BITS(bco) (BCO_BITMAP(bco)->bitmap)
244 #define BCO_BITMAP_SIZEW(bco) ((BCO_BITMAP_SIZE(bco) + BITS_IN(StgWord) - 1) \
247 /* -----------------------------------------------------------------------------
248 Dynamic stack frames for generic heap checks.
250 These generic heap checks are slow, but have the advantage of being
251 usable in a variety of situations.
253 The one restriction is that any relevant SRTs must already be pointed
254 to from the stack. The return address doesn't need to have an info
255 table attached: hence it can be any old code pointer.
257 The liveness mask contains a 1 at bit n, if register Rn contains a
258 non-pointer. The contents of all 8 vanilla registers are always saved
259 on the stack; the liveness mask tells the GC which ones contain
262 Good places to use a generic heap check:
264 - case alternatives (the return address with an SRT is already
267 - primitives (no SRT required).
269 The stack frame layout for a RET_DYN is like this:
271 some pointers |-- RET_DYN_PTRS(liveness) words
272 some nonpointers |-- RET_DYN_NONPTRS(liveness) words
275 D1-2 |-- RET_DYN_NONPTR_REGS_SIZE words
278 R1-8 |-- RET_DYN_BITMAP_SIZE words
281 liveness mask |-- StgRetDyn structure
284 we assume that the size of a double is always 2 pointers (wasting a
285 word when it is only one pointer, but avoiding lots of #ifdefs).
287 See Liveness.h for the macros (RET_DYN_PTRS() etc.).
289 NOTE: if you change the layout of RET_DYN stack frames, then you
290 might also need to adjust the value of RESERVED_STACK_WORDS in
292 -------------------------------------------------------------------------- */
295 const struct _StgInfoTable* info;
298 StgClosure * payload[FLEXIBLE_ARRAY];
301 /* A function return stack frame: used when saving the state for a
302 * garbage collection at a function entry point. The function
303 * arguments are on the stack, and we also save the function (its
304 * info table describes the pointerhood of the arguments).
306 * The stack frame size is also cached in the frame for convenience.
309 const struct _StgInfoTable* info;
312 StgClosure * payload[FLEXIBLE_ARRAY];
315 /* Concurrent communication objects */
319 struct StgTSO_ *head;
320 struct StgTSO_ *tail;
325 /* STM data structures
327 * StgTVar defines the only type that can be updated through the STM
330 * Note that various optimisations may be possible in order to use less
331 * space for these data structures at the cost of more complexity in the
334 * - In StgTVar, current_value and first_wait_queue_entry could be held in
335 * the same field: if any thread is waiting then its expected_value for
336 * the tvar is the current value.
338 * - In StgTRecHeader, it might be worthwhile having separate chunks
339 * of read-only and read-write locations. This would save a
340 * new_value field in the read-only locations.
342 * - In StgAtomicallyFrame, we could combine the waiting bit into
343 * the header (maybe a different info tbl for a waiting transaction).
344 * This means we can specialise the code for the atomically frame
345 * (it immediately switches on frame->waiting anyway).
348 typedef struct StgTVarWaitQueue_ {
350 struct StgTSO_ *waiting_tso;
351 struct StgTVarWaitQueue_ *next_queue_entry;
352 struct StgTVarWaitQueue_ *prev_queue_entry;
357 StgClosure *volatile current_value;
358 StgTVarWaitQueue *volatile first_wait_queue_entry;
359 #if defined(THREADED_RTS)
360 StgInt volatile num_updates;
364 /* new_value == expected_value for read-only accesses */
365 /* new_value is a StgTVarWaitQueue entry when trec in state TREC_WAITING */
368 StgClosure *expected_value;
369 StgClosure *new_value;
370 #if defined(THREADED_RTS)
375 #define TREC_CHUNK_NUM_ENTRIES 16
377 typedef struct StgTRecChunk_ {
379 struct StgTRecChunk_ *prev_chunk;
380 StgWord next_entry_idx;
381 TRecEntry entries[TREC_CHUNK_NUM_ENTRIES];
385 TREC_ACTIVE, /* Transaction in progress, outcome undecided */
386 TREC_CONDEMNED, /* Transaction in progress, inconsistent / out of date reads */
387 TREC_COMMITTED, /* Transaction has committed, now updating tvars */
388 TREC_ABORTED, /* Transaction has aborted, now reverting tvars */
389 TREC_WAITING, /* Transaction currently waiting */
392 typedef struct StgTRecHeader_ {
395 struct StgTRecHeader_ *enclosing_trec;
396 StgTRecChunk *current_chunk;
402 } StgAtomicallyFrame;
411 StgBool running_alt_code;
412 StgClosure *first_code;
413 StgClosure *alt_code;
414 StgTRecHeader *first_code_trec;
415 } StgCatchRetryFrame;
417 #if defined(PAR) || defined(GRAN)
419 StgBlockingQueueElement is a ``collective type'' representing the types
420 of closures that can be found on a blocking queue: StgTSO, StgRBHSave,
421 StgBlockedFetch. (StgRBHSave can only appear at the end of a blocking
422 queue). Logically, this is a union type, but defining another struct
423 with a common layout is easier to handle in the code.
424 Note that in the standard setup only StgTSOs can be on a blocking queue.
425 This is one of the main reasons for slightly different code in files
428 typedef struct StgBlockingQueueElement_ {
430 struct StgBlockingQueueElement_ *link; /* next elem in BQ */
431 struct StgClosure_ *payload[FLEXIBLE_ARRAY];/* contents of the closure */
432 } StgBlockingQueueElement;
434 /* only difference to std code is type of the elem in the BQ */
435 typedef struct StgBlockingQueue_ {
437 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
440 /* this closure is hanging at the end of a blocking queue in (see RBH.c) */
441 typedef struct StgRBHSave_ {
443 StgClosure *payload[FLEXIBLE_ARRAY]; /* 2 words ripped out of the guts of the */
444 } StgRBHSave; /* closure holding the blocking queue */
446 typedef struct StgRBH_ {
448 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
454 /* global indirections aka FETCH_ME closures */
455 typedef struct StgFetchMe_ {
457 globalAddr *ga; /* ptr to unique id for a closure */
460 /* same contents as an ordinary StgBlockingQueue */
461 typedef struct StgFetchMeBlockingQueue_ {
463 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
464 } StgFetchMeBlockingQueue;
466 /* This is an entry in a blocking queue. It indicates a fetch request from a
467 TSO on another PE demanding the value of this closur. Note that a
468 StgBlockedFetch can only occur in a BQ. Once the node is evaluated and
469 updated with the result, the result will be sent back (the PE is encoded
470 in the globalAddr) and the StgBlockedFetch closure will be nuked.
472 typedef struct StgBlockedFetch_ {
474 struct StgBlockingQueueElement_ *link; /* next elem in the BQ */
475 StgClosure *node; /* node to fetch */
476 globalAddr ga; /* where to send the result to */
477 } StgBlockedFetch; /* NB: not just a ptr to a GA */
480 #endif /* CLOSURES_H */