ghc/includes/Updates.h

   1 /* -----------------------------------------------------------------------------
   2  * $Id: Updates.h,v 1.5 1999/01/18 15:21:42 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         TICK_UPDATED_SET_UPDATED(updclosure);                   \
  29         AWAKEN_BQ(updclosure);                                  \
  30         updateWithIndirection((StgClosure *)updclosure,         \
  31                               (StgClosure *)heapptr);
  32
  33 /* -----------------------------------------------------------------------------
  34    Awaken any threads waiting on this computation
  35    -------------------------------------------------------------------------- */
  36
  37 extern void awaken_blocked_queue(StgTSO *q);
  38
  39 #define AWAKEN_BQ(closure)                                              \
  40         if (closure->header.info == &BLACKHOLE_BQ_info) {               \
  41                 StgTSO *bq = ((StgBlockingQueue *)closure)->blocking_queue;\
  42                 if (bq != (StgTSO *)&END_TSO_QUEUE_closure) {           \
  43                         STGCALL1(awaken_blocked_queue, bq);             \
  44                 }                                                       \
  45         }
  46
  47
  48 /* -----------------------------------------------------------------------------
  49    Push an update frame on the stack.
  50    -------------------------------------------------------------------------- */
  51
  52 #if defined(PROFILING)
  53 #define PUSH_STD_CCCS(frame) frame->header.prof.ccs = CCCS
  54 #else
  55 #define PUSH_STD_CCCS(frame)
  56 #endif
  57
  58 extern const StgPolyInfoTable Upd_frame_info;
  59
  60 #define PUSH_UPD_FRAME(target, Sp_offset)                       \
  61         {                                                       \
  62                 StgUpdateFrame *__frame;                        \
  63                 TICK_UPDF_PUSHED();                             \
  64                 __frame = stgCast(StgUpdateFrame*,Sp + (Sp_offset)) - 1; \
  65                 SET_INFO(__frame,stgCast(StgInfoTable*,&Upd_frame_info));   \
  66                 __frame->link = Su;                             \
  67                 __frame->updatee = (StgClosure *)(target);      \
  68                 PUSH_STD_CCCS(__frame);                         \
  69                 Su = __frame;                                   \
  70         }
  71
  72 /* -----------------------------------------------------------------------------
  73    Entering CAFs
  74
  75    When a CAF is first entered, it creates a black hole in the heap,
  76    and updates itself with an indirection to this new black hole.
  77
  78    We update the CAF with an indirection to a newly-allocated black
  79    hole in the heap.  We also set the blocking queue on the newly
  80    allocated black hole to be empty.
  81
  82    Why do we make a black hole in the heap when we enter a CAF?
  83
  84        - for a  generational garbage collector, which needs a fast
  85          test for whether an updatee is in an old generation or not
  86
  87        - for the parallel system, which can implement updates more
  88          easily if the updatee is always in the heap. (allegedly).
  89
  90    When debugging, we maintain a separate CAF list so we can tell when
  91    a CAF has been garbage collected.
  92    -------------------------------------------------------------------------- */
  93
  94 /* ToDo: only call newCAF when debugging. */
  95
  96 extern void newCAF(StgClosure*);
  97
  98 #define UPD_CAF(cafptr, bhptr)                                  \
  99   {                                                             \
 100     SET_INFO((StgInd *)cafptr,&IND_STATIC_info);                \
 101     ((StgInd *)cafptr)->indirectee   = (StgClosure *)(bhptr);   \
 102     STGCALL1(newCAF,(StgClosure *)cafptr);                      \
 103   }
 104
 105 /* -----------------------------------------------------------------------------
 106    Update-related prototypes
 107    -------------------------------------------------------------------------- */
 108
 109 extern STGFUN(Upd_frame_entry);
 110
 111 extern const StgInfoTable PAP_info;
 112 STGFUN(PAP_entry);
 113
 114 EXTFUN(stg_update_PAP);
 115
 116 extern const StgInfoTable AP_UPD_info;
 117 STGFUN(AP_UPD_entry);
 118
 119 extern const StgInfoTable raise_info;
 120
 121 #endif /* UPDATES_H */