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 /* -----------------------------------------------------------------------------
38 The full fixed-size closure header
40 The size of the fixed header is the sum of the optional parts plus a single
41 word for the entry code pointer.
42 -------------------------------------------------------------------------- */
45 const struct _StgInfoTable* info;
54 /* -----------------------------------------------------------------------------
57 For any given closure type (defined in InfoTables.h), there is a
58 corresponding structure defined below. The name of the structure
59 is obtained by concatenating the closure type with '_closure'
60 -------------------------------------------------------------------------- */
62 /* All closures follow the generic format */
66 struct StgClosure_ *payload[FLEXIBLE_ARRAY];
69 /* What a stroke of luck - all our mutable closures follow the same
70 * basic layout, with the mutable link field as the second field after
71 * the header. This means the following structure is the supertype of
75 typedef struct StgMutClosure_ {
78 struct StgMutClosure_ *mut_link;
79 struct StgClosure_ *payload[FLEXIBLE_ARRAY];
89 StgHalfWord arity; /* zero if it is an AP */
91 StgClosure *fun; /* really points to a fun */
92 StgClosure *payload[FLEXIBLE_ARRAY];
95 // AP closures have the same layout, for convenience
100 StgWord size; // number of words in payload
102 StgClosure *payload[FLEXIBLE_ARRAY]; // contains a chunk of *stack*
107 StgClosure *indirectee;
112 StgClosure *indirectee;
113 StgMutClosure *mut_link;
118 StgClosure *indirectee;
119 StgClosure *static_link;
120 struct _StgInfoTable *saved_info;
126 StgWord payload[FLEXIBLE_ARRAY];
132 StgMutClosure *mut_link; /* mutable list */
133 StgClosure *payload[FLEXIBLE_ARRAY];
139 StgMutClosure *mut_link;
142 typedef struct _StgUpdateFrame {
149 StgInt exceptions_blocked;
165 } StgIntCharlikeClosure;
167 /* statically allocated */
172 typedef struct _StgForeignObj {
174 StgAddr data; /* pointer to data in non-haskell-land */
177 typedef struct _StgStableName {
182 typedef struct _StgWeak { /* Weak v */
185 StgClosure *value; /* v */
186 StgClosure *finalizer;
187 struct _StgWeak *link;
190 typedef struct _StgDeadWeak { /* Weak v */
192 struct _StgWeak *link;
195 /* Byte code objects. These are fixed size objects with pointers to
196 * four arrays, designed so that a BCO can be easily "re-linked" to
197 * other BCOs, to facilitate GHC's intelligent recompilation. The
198 * array of instructions is static and not re-generated when the BCO
199 * is re-linked, but the other 3 arrays will be regenerated.
201 * A BCO represents either a function or a stack frame. In each case,
202 * it needs a bitmap to describe to the garbage collector the
203 * pointerhood of its arguments/free variables respectively, and in
204 * the case of a function it also needs an arity. These are stored
205 * directly in the BCO, rather than in the instrs array, for two
207 * (a) speed: we need to get at the bitmap info quickly when
208 * the GC is examining APs and PAPs that point to this BCO
209 * (b) a subtle interaction with the compacting GC. In compacting
210 * GC, the info that describes the size/layout of a closure
211 * cannot be in an object more than one level of indirection
212 * away from the current object, because of the order in
213 * which pointers are updated to point to their new locations.
218 StgArrWords *instrs; // a pointer to an ArrWords
219 StgArrWords *literals; // a pointer to an ArrWords
220 StgMutArrPtrs *ptrs; // a pointer to a MutArrPtrs
221 StgArrWords *itbls; // a pointer to an ArrWords
222 StgHalfWord arity; // arity of this BCO
223 StgHalfWord size; // size of this BCO (in words)
224 StgWord bitmap[FLEXIBLE_ARRAY]; // an StgLargeBitmap
227 #define BCO_BITMAP(bco) ((StgLargeBitmap *)((StgBCO *)(bco))->bitmap)
228 #define BCO_BITMAP_SIZE(bco) (BCO_BITMAP(bco)->size)
229 #define BCO_BITMAP_BITS(bco) (BCO_BITMAP(bco)->bitmap)
230 #define BCO_BITMAP_SIZEW(bco) ((BCO_BITMAP_SIZE(bco) + BITS_IN(StgWord) - 1) \
233 /* -----------------------------------------------------------------------------
234 Dynamic stack frames for generic heap checks.
236 These generic heap checks are slow, but have the advantage of being
237 usable in a variety of situations.
239 The one restriction is that any relevant SRTs must already be pointed
240 to from the stack. The return address doesn't need to have an info
241 table attached: hence it can be any old code pointer.
243 The liveness mask contains a 1 at bit n, if register Rn contains a
244 non-pointer. The contents of all 8 vanilla registers are always saved
245 on the stack; the liveness mask tells the GC which ones contain
248 Good places to use a generic heap check:
250 - case alternatives (the return address with an SRT is already
253 - primitives (no SRT required).
255 The stack frame layout for a RET_DYN is like this:
257 some pointers |-- RET_DYN_PTRS(liveness) words
258 some nonpointers |-- RET_DYN_NONPTRS(liveness) words
261 D1-2 |-- RET_DYN_NONPTR_REGS_SIZE words
264 R1-8 |-- RET_DYN_BITMAP_SIZE words
267 liveness mask |-- StgRetDyn structure
270 we assume that the size of a double is always 2 pointers (wasting a
271 word when it is only one pointer, but avoiding lots of #ifdefs).
273 See Liveness.h for the macros (RET_DYN_PTRS() etc.).
275 NOTE: if you change the layout of RET_DYN stack frames, then you
276 might also need to adjust the value of RESERVED_STACK_WORDS in
278 -------------------------------------------------------------------------- */
281 const struct _StgInfoTable* info;
284 StgClosure * payload[FLEXIBLE_ARRAY];
287 /* A function return stack frame: used when saving the state for a
288 * garbage collection at a function entry point. The function
289 * arguments are on the stack, and we also save the function (its
290 * info table describes the pointerhood of the arguments).
292 * The stack frame size is also cached in the frame for convenience.
295 const struct _StgInfoTable* info;
298 StgClosure * payload[FLEXIBLE_ARRAY];
301 /* Concurrent communication objects */
305 struct StgTSO_ *head;
306 StgMutClosure *mut_link;
307 struct StgTSO_ *tail;
311 /* STM data structures
313 * StgTVar defines the only type that can be updated through the STM
316 * Note that various optimisations may be possible in order to use less
317 * space for these data structures at the cost of more complexity in the
320 * - In StgTVar, current_value and first_wait_queue_entry could be held in
321 * the same field: if any thread is waiting then its expected_value for
322 * the tvar is the current value.
324 * - In StgTRecHeader, it might be worthwhile having separate chunks
325 * of read-only and read-write locations. This would save a
326 * new_value field in the read-only locations.
329 typedef struct StgTVarWaitQueue_ {
331 struct StgTSO_ *waiting_tso;
332 StgMutClosure *mut_link;
333 struct StgTVarWaitQueue_ *next_queue_entry;
334 struct StgTVarWaitQueue_ *prev_queue_entry;
339 StgClosure *current_value;
340 StgMutClosure *mut_link;
341 StgTVarWaitQueue *first_wait_queue_entry;
344 // new_value == expected_value for read-only accesses
345 // new_value is a StgTVarWaitQueue entry when trec in state TREC_WAITING
348 StgClosure *expected_value;
349 StgClosure *new_value;
352 #define TREC_CHUNK_NUM_ENTRIES 256
354 typedef struct StgTRecChunk_ {
356 struct StgTRecChunk_ *prev_chunk;
357 StgMutClosure *mut_link;
358 StgWord next_entry_idx;
359 TRecEntry entries[TREC_CHUNK_NUM_ENTRIES];
363 TREC_ACTIVE, // Transaction in progress, outcome undecided
364 TREC_CANNOT_COMMIT, // Transaction in progress, inconsistent writes performed
365 TREC_MUST_ABORT, // Transaction in progress, inconsistent / out of date reads
366 TREC_COMMITTED, // Transaction has committed, now updating tvars
367 TREC_ABORTED, // Transaction has aborted, now reverting tvars
368 TREC_WAITING, // Transaction currently waiting
371 typedef struct StgTRecHeader_ {
374 StgMutClosure *mut_link;
375 struct StgTRecHeader_ *enclosing_trec;
376 StgTRecChunk *current_chunk;
383 } StgAtomicallyFrame;
392 StgBool running_alt_code;
393 StgClosure *first_code;
394 StgClosure *alt_code;
395 StgTRecHeader *first_code_trec;
396 } StgCatchRetryFrame;
398 #if defined(PAR) || defined(GRAN)
400 StgBlockingQueueElement is a ``collective type'' representing the types
401 of closures that can be found on a blocking queue: StgTSO, StgRBHSave,
402 StgBlockedFetch. (StgRBHSave can only appear at the end of a blocking
403 queue). Logically, this is a union type, but defining another struct
404 with a common layout is easier to handle in the code (same as for
406 Note that in the standard setup only StgTSOs can be on a blocking queue.
407 This is one of the main reasons for slightly different code in files
410 typedef struct StgBlockingQueueElement_ {
412 struct StgBlockingQueueElement_ *link; /* next elem in BQ */
413 StgMutClosure *mut_link; /* next elem in mutable list */
414 struct StgClosure_ *payload[FLEXIBLE_ARRAY];/* contents of the closure */
415 } StgBlockingQueueElement;
417 /* only difference to std code is type of the elem in the BQ */
418 typedef struct StgBlockingQueue_ {
420 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
421 StgMutClosure *mut_link; /* next elem in mutable list */
424 /* this closure is hanging at the end of a blocking queue in (see RBH.c) */
425 typedef struct StgRBHSave_ {
427 StgClosure *payload[FLEXIBLE_ARRAY]; /* 2 words ripped out of the guts of the */
428 } StgRBHSave; /* closure holding the blocking queue */
430 typedef struct StgRBH_ {
432 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
433 StgMutClosure *mut_link; /* next elem in mutable list */
438 typedef struct StgBlockingQueue_ {
440 struct StgTSO_ *blocking_queue;
441 StgMutClosure *mut_link;
447 /* global indirections aka FETCH_ME closures */
448 typedef struct StgFetchMe_ {
450 globalAddr *ga; /* ptr to unique id for a closure */
451 StgMutClosure *mut_link; /* next elem in mutable list */
454 /* same contents as an ordinary StgBlockingQueue */
455 typedef struct StgFetchMeBlockingQueue_ {
457 struct StgBlockingQueueElement_ *blocking_queue; /* start of the BQ */
458 StgMutClosure *mut_link; /* next elem in mutable list */
459 } StgFetchMeBlockingQueue;
461 /* This is an entry in a blocking queue. It indicates a fetch request from a
462 TSO on another PE demanding the value of this closur. Note that a
463 StgBlockedFetch can only occur in a BQ. Once the node is evaluated and
464 updated with the result, the result will be sent back (the PE is encoded
465 in the globalAddr) and the StgBlockedFetch closure will be nuked.
467 typedef struct StgBlockedFetch_ {
469 struct StgBlockingQueueElement_ *link; /* next elem in the BQ */
470 StgMutClosure *mut_link; /* next elem in mutable list */
471 StgClosure *node; /* node to fetch */
472 globalAddr ga; /* where to send the result to */
473 } StgBlockedFetch; /* NB: not just a ptr to a GA */
476 #endif /* CLOSURES_H */