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;
179 } StgIntCharlikeClosure;
181 /* statically allocated */
186 typedef struct _StgStableName {
191 typedef struct _StgWeak { /* Weak v */
194 StgClosure *value; /* v */
195 StgClosure *finalizer;
196 struct _StgWeak *link;
199 typedef struct _StgDeadWeak { /* Weak v */
201 struct _StgWeak *link;
204 /* Byte code objects. These are fixed size objects with pointers to
205 * four arrays, designed so that a BCO can be easily "re-linked" to
206 * other BCOs, to facilitate GHC's intelligent recompilation. The
207 * array of instructions is static and not re-generated when the BCO
208 * is re-linked, but the other 3 arrays will be regenerated.
210 * A BCO represents either a function or a stack frame. In each case,
211 * it needs a bitmap to describe to the garbage collector the
212 * pointerhood of its arguments/free variables respectively, and in
213 * the case of a function it also needs an arity. These are stored
214 * directly in the BCO, rather than in the instrs array, for two
216 * (a) speed: we need to get at the bitmap info quickly when
217 * the GC is examining APs and PAPs that point to this BCO
218 * (b) a subtle interaction with the compacting GC. In compacting
219 * GC, the info that describes the size/layout of a closure
220 * cannot be in an object more than one level of indirection
221 * away from the current object, because of the order in
222 * which pointers are updated to point to their new locations.
227 StgArrWords *instrs; /* a pointer to an ArrWords */
228 StgArrWords *literals; /* a pointer to an ArrWords */
229 StgMutArrPtrs *ptrs; /* a pointer to a MutArrPtrs */
230 StgHalfWord arity; /* arity of this BCO */
231 StgHalfWord size; /* size of this BCO (in words) */
232 StgWord bitmap[FLEXIBLE_ARRAY]; /* an StgLargeBitmap */
235 #define BCO_BITMAP(bco) ((StgLargeBitmap *)((StgBCO *)(bco))->bitmap)
236 #define BCO_BITMAP_SIZE(bco) (BCO_BITMAP(bco)->size)
237 #define BCO_BITMAP_BITS(bco) (BCO_BITMAP(bco)->bitmap)
238 #define BCO_BITMAP_SIZEW(bco) ((BCO_BITMAP_SIZE(bco) + BITS_IN(StgWord) - 1) \
241 /* -----------------------------------------------------------------------------
242 Dynamic stack frames for generic heap checks.
244 These generic heap checks are slow, but have the advantage of being
245 usable in a variety of situations.
247 The one restriction is that any relevant SRTs must already be pointed
248 to from the stack. The return address doesn't need to have an info
249 table attached: hence it can be any old code pointer.
251 The liveness mask contains a 1 at bit n, if register Rn contains a
252 non-pointer. The contents of all 8 vanilla registers are always saved
253 on the stack; the liveness mask tells the GC which ones contain
256 Good places to use a generic heap check:
258 - case alternatives (the return address with an SRT is already
261 - primitives (no SRT required).
263 The stack frame layout for a RET_DYN is like this:
265 some pointers |-- RET_DYN_PTRS(liveness) words
266 some nonpointers |-- RET_DYN_NONPTRS(liveness) words
269 D1-2 |-- RET_DYN_NONPTR_REGS_SIZE words
272 R1-8 |-- RET_DYN_BITMAP_SIZE words
275 liveness mask |-- StgRetDyn structure
278 we assume that the size of a double is always 2 pointers (wasting a
279 word when it is only one pointer, but avoiding lots of #ifdefs).
281 See Liveness.h for the macros (RET_DYN_PTRS() etc.).
283 NOTE: if you change the layout of RET_DYN stack frames, then you
284 might also need to adjust the value of RESERVED_STACK_WORDS in
286 -------------------------------------------------------------------------- */
289 const struct _StgInfoTable* info;
292 StgClosure * payload[FLEXIBLE_ARRAY];
295 /* A function return stack frame: used when saving the state for a
296 * garbage collection at a function entry point. The function
297 * arguments are on the stack, and we also save the function (its
298 * info table describes the pointerhood of the arguments).
300 * The stack frame size is also cached in the frame for convenience.
303 const struct _StgInfoTable* info;
306 StgClosure * payload[FLEXIBLE_ARRAY];
309 /* Concurrent communication objects */
313 struct StgTSO_ *head;
314 struct StgTSO_ *tail;
319 /* STM data structures
321 * StgTVar defines the only type that can be updated through the STM
324 * Note that various optimisations may be possible in order to use less
325 * space for these data structures at the cost of more complexity in the
328 * - In StgTVar, current_value and first_watch_queue_entry could be held in
329 * the same field: if any thread is waiting then its expected_value for
330 * the tvar is the current value.
332 * - In StgTRecHeader, it might be worthwhile having separate chunks
333 * of read-only and read-write locations. This would save a
334 * new_value field in the read-only locations.
336 * - In StgAtomicallyFrame, we could combine the waiting bit into
337 * the header (maybe a different info tbl for a waiting transaction).
338 * This means we can specialise the code for the atomically frame
339 * (it immediately switches on frame->waiting anyway).
342 typedef struct StgTRecHeader_ StgTRecHeader;
344 typedef struct StgTVarWatchQueue_ {
346 StgClosure *closure; // StgTSO or StgAtomicInvariant
347 struct StgTVarWatchQueue_ *next_queue_entry;
348 struct StgTVarWatchQueue_ *prev_queue_entry;
353 StgClosure *volatile current_value;
354 StgTVarWatchQueue *volatile first_watch_queue_entry;
355 #if defined(THREADED_RTS)
356 StgInt volatile num_updates;
363 StgTRecHeader *last_execution;
365 } StgAtomicInvariant;
367 /* new_value == expected_value for read-only accesses */
368 /* new_value is a StgTVarWatchQueue entry when trec in state TREC_WAITING */
371 StgClosure *expected_value;
372 StgClosure *new_value;
373 #if defined(THREADED_RTS)
378 #define TREC_CHUNK_NUM_ENTRIES 16
380 typedef struct StgTRecChunk_ {
382 struct StgTRecChunk_ *prev_chunk;
383 StgWord next_entry_idx;
384 TRecEntry entries[TREC_CHUNK_NUM_ENTRIES];
388 TREC_ACTIVE, /* Transaction in progress, outcome undecided */
389 TREC_CONDEMNED, /* Transaction in progress, inconsistent / out of date reads */
390 TREC_COMMITTED, /* Transaction has committed, now updating tvars */
391 TREC_ABORTED, /* Transaction has aborted, now reverting tvars */
392 TREC_WAITING, /* Transaction currently waiting */
395 typedef struct StgInvariantCheckQueue_ {
397 StgAtomicInvariant *invariant;
398 StgTRecHeader *my_execution;
399 struct StgInvariantCheckQueue_ *next_queue_entry;
400 } StgInvariantCheckQueue;
402 struct StgTRecHeader_ {
405 struct StgTRecHeader_ *enclosing_trec;
406 StgTRecChunk *current_chunk;
407 StgInvariantCheckQueue *invariants_to_check;
413 StgTVarWatchQueue *next_invariant_to_check;
414 } StgAtomicallyFrame;
424 StgBool running_alt_code;
425 StgClosure *first_code;
426 StgClosure *alt_code;
427 } StgCatchRetryFrame;
429 #if defined(PAR) || defined(GRAN)
431 StgBlockingQueueElement is a ``collective type'' representing the types
432 of closures that can be found on a blocking queue: StgTSO, StgRBHSave,
433 StgBlockedFetch. (StgRBHSave can only appear at the end of a blocking
434 queue). Logically, this is a union type, but defining another struct
435 with a common layout is easier to handle in the code.
436 Note that in the standard setup only StgTSOs can be on a blocking queue.
437 This is one of the main reasons for slightly different code in files
440 typedef struct StgBlockingQueueElement_ {
442 struct StgBlockingQueueElement_ *link; /* next elem in BQ */
443 struct StgClosure_ *payload[FLEXIBLE_ARRAY];/* contents of the closure */
444 } StgBlockingQueueElement;
446 /* only difference to std code is type of the elem in the BQ */
447 typedef struct StgBlockingQueue_ {
449 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
452 /* this closure is hanging at the end of a blocking queue in (see RBH.c) */
453 typedef struct StgRBHSave_ {
455 StgClosure *payload[FLEXIBLE_ARRAY]; /* 2 words ripped out of the guts of the */
456 } StgRBHSave; /* closure holding the blocking queue */
458 typedef struct StgRBH_ {
460 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
466 /* global indirections aka FETCH_ME closures */
467 typedef struct StgFetchMe_ {
469 globalAddr *ga; /* ptr to unique id for a closure */
472 /* same contents as an ordinary StgBlockingQueue */
473 typedef struct StgFetchMeBlockingQueue_ {
475 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
476 } StgFetchMeBlockingQueue;
478 /* This is an entry in a blocking queue. It indicates a fetch request from a
479 TSO on another PE demanding the value of this closur. Note that a
480 StgBlockedFetch can only occur in a BQ. Once the node is evaluated and
481 updated with the result, the result will be sent back (the PE is encoded
482 in the globalAddr) and the StgBlockedFetch closure will be nuked.
484 typedef struct StgBlockedFetch_ {
486 struct StgBlockingQueueElement_ *link; /* next elem in the BQ */
487 StgClosure *node; /* node to fetch */
488 globalAddr ga; /* where to send the result to */
489 } StgBlockedFetch; /* NB: not just a ptr to a GA */
492 #endif /* CLOSURES_H */