ghc/includes/Updates.h

   1 /* -----------------------------------------------------------------------------
   2  * $Id: Updates.h,v 1.10 1999/05/11 16:47:42 keithw Exp $
   3  *
   4  * (c) The GHC Team, 1998-1999
   5  *
   6  * Definitions related to updates.
   7  *
   8  * ---------------------------------------------------------------------------*/
   9
  10 #ifndef UPDATES_H
  11 #define UPDATES_H
  12
  13 /* -----------------------------------------------------------------------------
  14    Update a closure with an indirection.  This may also involve waking
  15    up a queue of blocked threads waiting on the result of this
  16    computation.
  17    -------------------------------------------------------------------------- */
  18
  19 /* ToDo: overwrite slop words with something safe in case sanity checking
  20  *       is turned on.
  21  *       (I think the fancy version of the GC is supposed to do this too.)
  22  */
  23
  24 /* This expands to a fair chunk of code, what with waking up threads
  25  * and checking whether we're updating something in a old generation.
  26  * preferably don't use this macro inline in compiled code.
  27  */
  28
  29 #ifdef TICKY_TICKY
  30 # define UPD_IND(updclosure, heapptr) UPD_PERM_IND(updclosure,heapptr)
  31 #else
  32 # define UPD_IND(updclosure, heapptr) UPD_REAL_IND(updclosure,heapptr)
  33 #endif
  34
  35 /* UPD_IND actually does a PERM_IND if TICKY_TICKY is on;
  36    if you *really* need an IND use UPD_REAL_IND
  37  */
  38 #define UPD_REAL_IND(updclosure, heapptr)                       \
  39         AWAKEN_BQ(updclosure);                                  \
  40         updateWithIndirection((StgClosure *)updclosure,         \
  41                               (StgClosure *)heapptr);
  42
  43 #if defined(PROFILING) || defined(TICKY_TICKY)
  44 #define UPD_PERM_IND(updclosure, heapptr)                       \
  45         AWAKEN_BQ(updclosure);                                  \
  46         updateWithPermIndirection((StgClosure *)updclosure,     \
  47                                   (StgClosure *)heapptr);
  48 #endif
  49
  50 /* -----------------------------------------------------------------------------
  51    Awaken any threads waiting on this computation
  52    -------------------------------------------------------------------------- */
  53
  54 extern void awaken_blocked_queue(StgTSO *q);
  55
  56 #define AWAKEN_BQ(closure)                                              \
  57         if (closure->header.info == &BLACKHOLE_BQ_info) {               \
  58                 StgTSO *bq = ((StgBlockingQueue *)closure)->blocking_queue;\
  59                 if (bq != (StgTSO *)&END_TSO_QUEUE_closure) {           \
  60                         STGCALL1(awaken_blocked_queue, bq);             \
  61                 }                                                       \
  62         }
  63
  64
  65 /* -----------------------------------------------------------------------------
  66    Push an update frame on the stack.
  67    -------------------------------------------------------------------------- */
  68
  69 #if defined(PROFILING)
  70 #define PUSH_STD_CCCS(frame) frame->header.prof.ccs = CCCS
  71 #else
  72 #define PUSH_STD_CCCS(frame)
  73 #endif
  74
  75 extern DLL_IMPORT_DATA const StgPolyInfoTable Upd_frame_info;
  76
  77 #define PUSH_UPD_FRAME(target, Sp_offset)                       \
  78         {                                                       \
  79                 StgUpdateFrame *__frame;                        \
  80                 TICK_UPDF_PUSHED(target, GET_INFO((StgClosure*)target));                        \
  81                 __frame = stgCast(StgUpdateFrame*,Sp + (Sp_offset)) - 1; \
  82                 SET_INFO(__frame,stgCast(StgInfoTable*,&Upd_frame_info));   \
  83                 __frame->link = Su;                             \
  84                 __frame->updatee = (StgClosure *)(target);      \
  85                 PUSH_STD_CCCS(__frame);                         \
  86                 Su = __frame;                                   \
  87         }
  88
  89 /* -----------------------------------------------------------------------------
  90    Entering CAFs
  91
  92    When a CAF is first entered, it creates a black hole in the heap,
  93    and updates itself with an indirection to this new black hole.
  94
  95    We update the CAF with an indirection to a newly-allocated black
  96    hole in the heap.  We also set the blocking queue on the newly
  97    allocated black hole to be empty.
  98
  99    Why do we make a black hole in the heap when we enter a CAF?
 100
 101        - for a  generational garbage collector, which needs a fast
 102          test for whether an updatee is in an old generation or not
 103
 104        - for the parallel system, which can implement updates more
 105          easily if the updatee is always in the heap. (allegedly).
 106
 107    When debugging, we maintain a separate CAF list so we can tell when
 108    a CAF has been garbage collected.
 109    -------------------------------------------------------------------------- */
 110
 111 /* ToDo: only call newCAF when debugging. */
 112
 113 extern void newCAF(StgClosure*);
 114
 115 #define UPD_CAF(cafptr, bhptr)                                  \
 116   {                                                             \
 117     SET_INFO((StgInd *)cafptr,(const StgInfoTable*)&IND_STATIC_info);           \
 118     ((StgInd *)cafptr)->indirectee   = (StgClosure *)(bhptr);   \
 119     STGCALL1(newCAF,(StgClosure *)cafptr);                      \
 120   }
 121
 122 /* -----------------------------------------------------------------------------
 123    Update-related prototypes
 124    -------------------------------------------------------------------------- */
 125
 126 DLL_IMPORT_RTS extern STGFUN(Upd_frame_entry);
 127
 128 extern DLL_IMPORT_DATA const StgInfoTable PAP_info;
 129 DLL_IMPORT_RTS STGFUN(PAP_entry);
 130
 131 EXTFUN_RTS(stg_update_PAP);
 132
 133 extern DLL_IMPORT_DATA const StgInfoTable AP_UPD_info;
 134 DLL_IMPORT_RTS STGFUN(AP_UPD_entry);
 135
 136 extern DLL_IMPORT_DATA const StgInfoTable raise_info;
 137
 138 #endif /* UPDATES_H */