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/* ----------------------------------------------------------------------------
*
* (c) The GHC Team, 1998-2004
*
* Closures
*
* -------------------------------------------------------------------------- */

#ifndef RTS_STORAGE_CLOSURES_H
#define RTS_STORAGE_CLOSURES_H

/*
* The Layout of a closure header depends on which kind of system we're
* compiling for: profiling, parallel, ticky, etc.
*/

/* -----------------------------------------------------------------------------
The profiling header
-------------------------------------------------------------------------- */

typedef struct {
  CostCentreStack *ccs;
  union {
    struct _RetainerSet *rs; /* Retainer Set */
    StgWord ldvw; /* Lag/Drag/Void Word */
  } hp;
} StgProfHeader;

/* -----------------------------------------------------------------------------
The SMP header
A thunk has a padding word to take the updated value. This is so
that the update doesn't overwrite the payload, so we can avoid
needing to lock the thunk during entry and update.
Note: this doesn't apply to THUNK_STATICs, which have no payload.

Note: we leave this padding word in all ways, rather than just SMP,
so that we don't have to recompile all our libraries for SMP.
-------------------------------------------------------------------------- */

typedef struct {
    StgWord pad;
} StgSMPThunkHeader;

/* -----------------------------------------------------------------------------
The full fixed-size closure header

The size of the fixed header is the sum of the optional parts plus a single
word for the entry code pointer.
-------------------------------------------------------------------------- */

typedef struct {
    const StgInfoTable* info;
#ifdef PROFILING
    StgProfHeader prof;
#endif
} StgHeader;

typedef struct {
    const StgInfoTable* info;
#ifdef PROFILING
    StgProfHeader prof;
#endif
    StgSMPThunkHeader smp;
} StgThunkHeader;

#define THUNK_EXTRA_HEADER_W (sizeofW(StgThunkHeader)-sizeofW(StgHeader))

/* -----------------------------------------------------------------------------
Closure Types

For any given closure type (defined in InfoTables.h), there is a
corresponding structure defined below. The name of the structure
is obtained by concatenating the closure type with '_closure'
-------------------------------------------------------------------------- */

/* All closures follow the generic format */

typedef struct StgClosure_ {
    StgHeader header;
    struct StgClosure_ *payload[FLEXIBLE_ARRAY];
} *StgClosurePtr; // StgClosure defined in Rts.h

typedef struct {
    StgThunkHeader header;
    struct StgClosure_ *payload[FLEXIBLE_ARRAY];
} StgThunk;

typedef struct {
    StgThunkHeader header;
    StgClosure *selectee;
} StgSelector;

typedef struct {
    StgHeader header;
    StgHalfWord arity; /* zero if it is an AP */
    StgHalfWord n_args;
    StgClosure *fun; /* really points to a fun */
    StgClosure *payload[FLEXIBLE_ARRAY];
} StgPAP;

typedef struct {
    StgThunkHeader header;
    StgHalfWord arity; /* zero if it is an AP */
    StgHalfWord n_args;
    StgClosure *fun; /* really points to a fun */
    StgClosure *payload[FLEXIBLE_ARRAY];
} StgAP;

typedef struct {
    StgThunkHeader header;
    StgWord size; /* number of words in payload */
    StgClosure *fun;
    StgClosure *payload[FLEXIBLE_ARRAY]; /* contains a chunk of *stack* */
} StgAP_STACK;

typedef struct {
    StgHeader header;
    StgClosure *indirectee;
} StgInd;

typedef struct {
    StgHeader header;
    StgClosure *indirectee;
    StgClosure *static_link;
    const StgInfoTable *saved_info;
} StgIndStatic;

typedef struct StgBlockingQueue_ {
    StgHeader header;
    struct StgBlockingQueue_ *link; // here so it looks like an IND
    StgClosure *bh; // the BLACKHOLE
    StgTSO *owner;
    struct MessageBlackHole_ *queue;
} StgBlockingQueue;

typedef struct {
    StgHeader header;
    StgWord bytes;
    StgWord payload[FLEXIBLE_ARRAY];
} StgArrWords;

typedef struct {
    StgHeader header;
    StgWord ptrs;
    StgWord size; // ptrs plus card table
    StgClosure *payload[FLEXIBLE_ARRAY];
    // see also: StgMutArrPtrs macros in ClosureMacros.h
} StgMutArrPtrs;

typedef struct {
    StgHeader header;
    StgClosure *var;
} StgMutVar;

typedef struct _StgUpdateFrame {
    StgHeader header;
    StgClosure *updatee;
} StgUpdateFrame;

typedef struct {
    StgHeader header;
    StgWord exceptions_blocked;
    StgClosure *handler;
} StgCatchFrame;

typedef struct {
    const StgInfoTable* info;
    struct StgStack_ *next_chunk;
} StgUnderflowFrame;

typedef struct {
    StgHeader header;
} StgStopFrame;

typedef struct {
  StgHeader header;
  StgWord data;
} StgIntCharlikeClosure;

/* statically allocated */
typedef struct {
  StgHeader header;
} StgRetry;

typedef struct _StgStableName {
  StgHeader header;
  StgWord sn;
} StgStableName;

typedef struct _StgWeak { /* Weak v */
  StgHeader header;
  StgClosure *cfinalizer;
  StgClosure *key;
  StgClosure *value; /* v */
  StgClosure *finalizer;
  struct _StgWeak *link;
} StgWeak;

typedef struct _StgDeadWeak { /* Weak v */
  StgHeader header;
  struct _StgWeak *link;
} StgDeadWeak;

/* 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 */
    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 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 StgInfoTable* info;
    StgWord size;
    StgClosure * fun;
    StgClosure * payload[FLEXIBLE_ARRAY];
} StgRetFun;

/* Concurrent communication objects */

typedef struct StgMVarTSOQueue_ {
    StgHeader header;
    struct StgMVarTSOQueue_ *link;
    struct StgTSO_ *tso;
} StgMVarTSOQueue;

typedef struct {
    StgHeader header;
    struct StgMVarTSOQueue_ *head;
    struct StgMVarTSOQueue_ *tail;
    StgClosure* value;
} StgMVar;


/* STM data structures
*
* StgTVar defines the only type that can be updated through the STM
* interface.
*
* Note that various optimisations may be possible in order to use less
* space for these data structures at the cost of more complexity in the
* implementation:
*
* - In StgTVar, current_value and first_watch_queue_entry could be held in
* the same field: if any thread is waiting then its expected_value for
* the tvar is the current value.
*
* - In StgTRecHeader, it might be worthwhile having separate chunks
* of read-only and read-write locations. This would save a
* new_value field in the read-only locations.
*
* - In StgAtomicallyFrame, we could combine the waiting bit into
* the header (maybe a different info tbl for a waiting transaction).
* This means we can specialise the code for the atomically frame
* (it immediately switches on frame->waiting anyway).
*/

typedef struct StgTRecHeader_ StgTRecHeader;

typedef struct StgTVarWatchQueue_ {
  StgHeader header;
  StgClosure *closure; // StgTSO or StgAtomicInvariant
  struct StgTVarWatchQueue_ *next_queue_entry;
  struct StgTVarWatchQueue_ *prev_queue_entry;
} StgTVarWatchQueue;

typedef struct {
  StgHeader header;
  StgClosure *volatile current_value;
  StgTVarWatchQueue *volatile first_watch_queue_entry;
#if defined(THREADED_RTS)
  StgInt volatile num_updates;
#endif
} StgTVar;

typedef struct {
  StgHeader header;
  StgClosure *code;
  StgTRecHeader *last_execution;
  StgWord lock;
} StgAtomicInvariant;

/* new_value == expected_value for read-only accesses */
/* new_value is a StgTVarWatchQueue entry when trec in state TREC_WAITING */
typedef struct {
  StgTVar *tvar;
  StgClosure *expected_value;
  StgClosure *new_value;
#if defined(THREADED_RTS)
  StgInt num_updates;
#endif
} TRecEntry;

#define TREC_CHUNK_NUM_ENTRIES 16

typedef struct StgTRecChunk_ {
  StgHeader header;
  struct StgTRecChunk_ *prev_chunk;
  StgWord next_entry_idx;
  TRecEntry entries[TREC_CHUNK_NUM_ENTRIES];
} StgTRecChunk;

typedef enum {
  TREC_ACTIVE, /* Transaction in progress, outcome undecided */
  TREC_CONDEMNED, /* Transaction in progress, inconsistent / out of date reads */
  TREC_COMMITTED, /* Transaction has committed, now updating tvars */
  TREC_ABORTED, /* Transaction has aborted, now reverting tvars */
  TREC_WAITING, /* Transaction currently waiting */
} TRecState;

typedef struct StgInvariantCheckQueue_ {
  StgHeader header;
  StgAtomicInvariant *invariant;
  StgTRecHeader *my_execution;
  struct StgInvariantCheckQueue_ *next_queue_entry;
} StgInvariantCheckQueue;

struct StgTRecHeader_ {
  StgHeader header;
  struct StgTRecHeader_ *enclosing_trec;
  StgTRecChunk *current_chunk;
  StgInvariantCheckQueue *invariants_to_check;
  TRecState state;
};

typedef struct {
  StgHeader header;
  StgClosure *code;
  StgTVarWatchQueue *next_invariant_to_check;
  StgClosure *result;
} StgAtomicallyFrame;

typedef struct {
  StgHeader header;
  StgClosure *code;
  StgClosure *handler;
} StgCatchSTMFrame;

typedef struct {
  StgHeader header;
  StgBool running_alt_code;
  StgClosure *first_code;
  StgClosure *alt_code;
} StgCatchRetryFrame;

/* ----------------------------------------------------------------------------
Messages
------------------------------------------------------------------------- */

typedef struct Message_ {
    StgHeader header;
    struct Message_ *link;
} Message;

typedef struct MessageWakeup_ {
    StgHeader header;
    Message *link;
    StgTSO *tso;
} MessageWakeup;

typedef struct MessageThrowTo_ {
    StgHeader header;
    struct MessageThrowTo_ *link;
    StgTSO *source;
    StgTSO *target;
    StgClosure *exception;
} MessageThrowTo;

typedef struct MessageBlackHole_ {
    StgHeader header;
    struct MessageBlackHole_ *link;
    StgTSO *tso;
    StgClosure *bh;
} MessageBlackHole;

#endif /* RTS_STORAGE_CLOSURES_H */
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