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 StgHalfWord arity; /* arity of this BCO */
236 StgHalfWord size; /* size of this BCO (in words) */
237 StgWord bitmap[FLEXIBLE_ARRAY]; /* an StgLargeBitmap */
240 #define BCO_BITMAP(bco) ((StgLargeBitmap *)((StgBCO *)(bco))->bitmap)
241 #define BCO_BITMAP_SIZE(bco) (BCO_BITMAP(bco)->size)
242 #define BCO_BITMAP_BITS(bco) (BCO_BITMAP(bco)->bitmap)
243 #define BCO_BITMAP_SIZEW(bco) ((BCO_BITMAP_SIZE(bco) + BITS_IN(StgWord) - 1) \
246 /* -----------------------------------------------------------------------------
247 Dynamic stack frames for generic heap checks.
249 These generic heap checks are slow, but have the advantage of being
250 usable in a variety of situations.
252 The one restriction is that any relevant SRTs must already be pointed
253 to from the stack. The return address doesn't need to have an info
254 table attached: hence it can be any old code pointer.
256 The liveness mask contains a 1 at bit n, if register Rn contains a
257 non-pointer. The contents of all 8 vanilla registers are always saved
258 on the stack; the liveness mask tells the GC which ones contain
261 Good places to use a generic heap check:
263 - case alternatives (the return address with an SRT is already
266 - primitives (no SRT required).
268 The stack frame layout for a RET_DYN is like this:
270 some pointers |-- RET_DYN_PTRS(liveness) words
271 some nonpointers |-- RET_DYN_NONPTRS(liveness) words
274 D1-2 |-- RET_DYN_NONPTR_REGS_SIZE words
277 R1-8 |-- RET_DYN_BITMAP_SIZE words
280 liveness mask |-- StgRetDyn structure
283 we assume that the size of a double is always 2 pointers (wasting a
284 word when it is only one pointer, but avoiding lots of #ifdefs).
286 See Liveness.h for the macros (RET_DYN_PTRS() etc.).
288 NOTE: if you change the layout of RET_DYN stack frames, then you
289 might also need to adjust the value of RESERVED_STACK_WORDS in
291 -------------------------------------------------------------------------- */
294 const struct _StgInfoTable* info;
297 StgClosure * payload[FLEXIBLE_ARRAY];
300 /* A function return stack frame: used when saving the state for a
301 * garbage collection at a function entry point. The function
302 * arguments are on the stack, and we also save the function (its
303 * info table describes the pointerhood of the arguments).
305 * The stack frame size is also cached in the frame for convenience.
308 const struct _StgInfoTable* info;
311 StgClosure * payload[FLEXIBLE_ARRAY];
314 /* Concurrent communication objects */
318 struct StgTSO_ *head;
319 struct StgTSO_ *tail;
324 /* STM data structures
326 * StgTVar defines the only type that can be updated through the STM
329 * Note that various optimisations may be possible in order to use less
330 * space for these data structures at the cost of more complexity in the
333 * - In StgTVar, current_value and first_watch_queue_entry could be held in
334 * the same field: if any thread is waiting then its expected_value for
335 * the tvar is the current value.
337 * - In StgTRecHeader, it might be worthwhile having separate chunks
338 * of read-only and read-write locations. This would save a
339 * new_value field in the read-only locations.
341 * - In StgAtomicallyFrame, we could combine the waiting bit into
342 * the header (maybe a different info tbl for a waiting transaction).
343 * This means we can specialise the code for the atomically frame
344 * (it immediately switches on frame->waiting anyway).
347 typedef struct StgTRecHeader_ StgTRecHeader;
349 typedef struct StgTVarWatchQueue_ {
351 StgClosure *closure; // StgTSO or StgAtomicInvariant
352 struct StgTVarWatchQueue_ *next_queue_entry;
353 struct StgTVarWatchQueue_ *prev_queue_entry;
358 StgClosure *volatile current_value;
359 StgTVarWatchQueue *volatile first_watch_queue_entry;
360 #if defined(THREADED_RTS)
361 StgInt volatile num_updates;
368 StgTRecHeader *last_execution;
370 } StgAtomicInvariant;
372 /* new_value == expected_value for read-only accesses */
373 /* new_value is a StgTVarWatchQueue entry when trec in state TREC_WAITING */
376 StgClosure *expected_value;
377 StgClosure *new_value;
378 #if defined(THREADED_RTS)
383 #define TREC_CHUNK_NUM_ENTRIES 16
385 typedef struct StgTRecChunk_ {
387 struct StgTRecChunk_ *prev_chunk;
388 StgWord next_entry_idx;
389 TRecEntry entries[TREC_CHUNK_NUM_ENTRIES];
393 TREC_ACTIVE, /* Transaction in progress, outcome undecided */
394 TREC_CONDEMNED, /* Transaction in progress, inconsistent / out of date reads */
395 TREC_COMMITTED, /* Transaction has committed, now updating tvars */
396 TREC_ABORTED, /* Transaction has aborted, now reverting tvars */
397 TREC_WAITING, /* Transaction currently waiting */
400 typedef struct StgInvariantCheckQueue_ {
402 StgAtomicInvariant *invariant;
403 StgTRecHeader *my_execution;
404 struct StgInvariantCheckQueue_ *next_queue_entry;
405 } StgInvariantCheckQueue;
407 struct StgTRecHeader_ {
410 struct StgTRecHeader_ *enclosing_trec;
411 StgTRecChunk *current_chunk;
412 StgInvariantCheckQueue *invariants_to_check;
418 StgTVarWatchQueue *next_invariant_to_check;
419 } StgAtomicallyFrame;
429 StgBool running_alt_code;
430 StgClosure *first_code;
431 StgClosure *alt_code;
432 } StgCatchRetryFrame;
434 #if defined(PAR) || defined(GRAN)
436 StgBlockingQueueElement is a ``collective type'' representing the types
437 of closures that can be found on a blocking queue: StgTSO, StgRBHSave,
438 StgBlockedFetch. (StgRBHSave can only appear at the end of a blocking
439 queue). Logically, this is a union type, but defining another struct
440 with a common layout is easier to handle in the code.
441 Note that in the standard setup only StgTSOs can be on a blocking queue.
442 This is one of the main reasons for slightly different code in files
445 typedef struct StgBlockingQueueElement_ {
447 struct StgBlockingQueueElement_ *link; /* next elem in BQ */
448 struct StgClosure_ *payload[FLEXIBLE_ARRAY];/* contents of the closure */
449 } StgBlockingQueueElement;
451 /* only difference to std code is type of the elem in the BQ */
452 typedef struct StgBlockingQueue_ {
454 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
457 /* this closure is hanging at the end of a blocking queue in (see RBH.c) */
458 typedef struct StgRBHSave_ {
460 StgClosure *payload[FLEXIBLE_ARRAY]; /* 2 words ripped out of the guts of the */
461 } StgRBHSave; /* closure holding the blocking queue */
463 typedef struct StgRBH_ {
465 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
471 /* global indirections aka FETCH_ME closures */
472 typedef struct StgFetchMe_ {
474 globalAddr *ga; /* ptr to unique id for a closure */
477 /* same contents as an ordinary StgBlockingQueue */
478 typedef struct StgFetchMeBlockingQueue_ {
480 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
481 } StgFetchMeBlockingQueue;
483 /* This is an entry in a blocking queue. It indicates a fetch request from a
484 TSO on another PE demanding the value of this closur. Note that a
485 StgBlockedFetch can only occur in a BQ. Once the node is evaluated and
486 updated with the result, the result will be sent back (the PE is encoded
487 in the globalAddr) and the StgBlockedFetch closure will be nuked.
489 typedef struct StgBlockedFetch_ {
491 struct StgBlockingQueueElement_ *link; /* next elem in the BQ */
492 StgClosure *node; /* node to fetch */
493 globalAddr ga; /* where to send the result to */
494 } StgBlockedFetch; /* NB: not just a ptr to a GA */
497 #endif /* CLOSURES_H */