ghc/includes/Updates.h

   1 /* -----------------------------------------------------------------------------
   2  * $Id: Updates.h,v 1.6 1999/01/21 10:31:45 simonm Exp $
   3  *
   4  * Definitions related to updates.
   5  *
   6  * ---------------------------------------------------------------------------*/
   7
   8 #ifndef UPDATES_H
   9 #define UPDATES_H
  10
  11 /* -----------------------------------------------------------------------------
  12    Update a closure with an indirection.  This may also involve waking
  13    up a queue of blocked threads waiting on the result of this
  14    computation.
  15    -------------------------------------------------------------------------- */
  16
  17 /* ToDo: overwrite slop words with something safe in case sanity checking
  18  *       is turned on.
  19  *       (I think the fancy version of the GC is supposed to do this too.)
  20  */
  21
  22 /* This expands to a fair chunk of code, what with waking up threads
  23  * and checking whether we're updating something in a old generation.
  24  * preferably don't use this macro inline in compiled code.
  25  */
  26
  27 #define UPD_IND(updclosure, heapptr)                            \
  28         AWAKEN_BQ(updclosure);                                  \
  29         updateWithIndirection((StgClosure *)updclosure,         \
  30                               (StgClosure *)heapptr);
  31
  32 /* -----------------------------------------------------------------------------
  33    Awaken any threads waiting on this computation
  34    -------------------------------------------------------------------------- */
  35
  36 extern void awaken_blocked_queue(StgTSO *q);
  37
  38 #define AWAKEN_BQ(closure)                                              \
  39         if (closure->header.info == &BLACKHOLE_BQ_info) {               \
  40                 StgTSO *bq = ((StgBlockingQueue *)closure)->blocking_queue;\
  41                 if (bq != (StgTSO *)&END_TSO_QUEUE_closure) {           \
  42                         STGCALL1(awaken_blocked_queue, bq);             \
  43                 }                                                       \
  44         }
  45
  46
  47 /* -----------------------------------------------------------------------------
  48    Push an update frame on the stack.
  49    -------------------------------------------------------------------------- */
  50
  51 #if defined(PROFILING)
  52 #define PUSH_STD_CCCS(frame) frame->header.prof.ccs = CCCS
  53 #else
  54 #define PUSH_STD_CCCS(frame)
  55 #endif
  56
  57 extern const StgPolyInfoTable Upd_frame_info;
  58
  59 #define PUSH_UPD_FRAME(target, Sp_offset)                       \
  60         {                                                       \
  61                 StgUpdateFrame *__frame;                        \
  62                 TICK_UPDF_PUSHED();                             \
  63                 __frame = stgCast(StgUpdateFrame*,Sp + (Sp_offset)) - 1; \
  64                 SET_INFO(__frame,stgCast(StgInfoTable*,&Upd_frame_info));   \
  65                 __frame->link = Su;                             \
  66                 __frame->updatee = (StgClosure *)(target);      \
  67                 PUSH_STD_CCCS(__frame);                         \
  68                 Su = __frame;                                   \
  69         }
  70
  71 /* -----------------------------------------------------------------------------
  72    Entering CAFs
  73
  74    When a CAF is first entered, it creates a black hole in the heap,
  75    and updates itself with an indirection to this new black hole.
  76
  77    We update the CAF with an indirection to a newly-allocated black
  78    hole in the heap.  We also set the blocking queue on the newly
  79    allocated black hole to be empty.
  80
  81    Why do we make a black hole in the heap when we enter a CAF?
  82
  83        - for a  generational garbage collector, which needs a fast
  84          test for whether an updatee is in an old generation or not
  85
  86        - for the parallel system, which can implement updates more
  87          easily if the updatee is always in the heap. (allegedly).
  88
  89    When debugging, we maintain a separate CAF list so we can tell when
  90    a CAF has been garbage collected.
  91    -------------------------------------------------------------------------- */
  92
  93 /* ToDo: only call newCAF when debugging. */
  94
  95 extern void newCAF(StgClosure*);
  96
  97 #define UPD_CAF(cafptr, bhptr)                                  \
  98   {                                                             \
  99     SET_INFO((StgInd *)cafptr,&IND_STATIC_info);                \
 100     ((StgInd *)cafptr)->indirectee   = (StgClosure *)(bhptr);   \
 101     STGCALL1(newCAF,(StgClosure *)cafptr);                      \
 102   }
 103
 104 /* -----------------------------------------------------------------------------
 105    Update-related prototypes
 106    -------------------------------------------------------------------------- */
 107
 108 extern STGFUN(Upd_frame_entry);
 109
 110 extern const StgInfoTable PAP_info;
 111 STGFUN(PAP_entry);
 112
 113 EXTFUN(stg_update_PAP);
 114
 115 extern const StgInfoTable AP_UPD_info;
 116 STGFUN(AP_UPD_entry);
 117
 118 extern const StgInfoTable raise_info;
 119
 120 #endif /* UPDATES_H */