ghc/includes/Updates.h

   1 /* -----------------------------------------------------------------------------
   2  * $Id: Updates.h,v 1.15 1999/11/09 15:47:09 simonmar 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 #ifdef SMP
  39 #define UPD_REAL_IND(updclosure, heapptr)                               \
  40    {                                                                    \
  41         const StgInfoTable *info;                                       \
  42         if (Bdescr((P_)updclosure)->back != (bdescr *)BaseReg) {        \
  43                 info = LOCK_CLOSURE(updclosure);                        \
  44         } else {                                                        \
  45                 info = updclosure->header.info;                         \
  46         }                                                               \
  47         AWAKEN_BQ(info,updclosure);                                     \
  48         updateWithIndirection(info,                                     \
  49                               (StgClosure *)updclosure,                 \
  50                               (StgClosure *)heapptr);                   \
  51    }
  52 #else
  53 #define UPD_REAL_IND(updclosure, heapptr)               \
  54    {                                                    \
  55         const StgInfoTable *info;                       \
  56         info = ((StgClosure *)updclosure)->header.info; \
  57         AWAKEN_BQ(info,updclosure);                     \
  58         updateWithIndirection(info,                     \
  59                               (StgClosure *)updclosure, \
  60                               (StgClosure *)heapptr);   \
  61    }
  62 #endif
  63
  64 #if defined(PROFILING) || defined(TICKY_TICKY)
  65 #define UPD_PERM_IND(updclosure, heapptr)                       \
  66    {                                                            \
  67         const StgInfoTable *info;                               \
  68         info = ((StgClosure *)updclosure)->header.info;         \
  69         AWAKEN_BQ(info,updclosure);                             \
  70         updateWithPermIndirection(info,                         \
  71                                   (StgClosure *)updclosure,     \
  72                                   (StgClosure *)heapptr);       \
  73    }
  74 #endif
  75
  76 #ifdef SMP
  77 #define UPD_IND_NOLOCK(updclosure, heapptr)                             \
  78    {                                                                    \
  79         const StgInfoTable *info;                                       \
  80         info = updclosure->header.info;                                 \
  81         AWAKEN_BQ(info,updclosure);                                     \
  82         updateWithIndirection(info,                                     \
  83                               (StgClosure *)updclosure,                 \
  84                               (StgClosure *)heapptr);                   \
  85    }
  86 #else
  87 #define UPD_IND_NOLOCK(updclosure,heapptr) UPD_IND(updclosure,heapptr)
  88 #endif
  89
  90 /* -----------------------------------------------------------------------------
  91    Awaken any threads waiting on this computation
  92    -------------------------------------------------------------------------- */
  93
  94 extern void awakenBlockedQueue(StgTSO *q);
  95
  96 #define AWAKEN_BQ(info,closure)                                         \
  97         if (info == &BLACKHOLE_BQ_info) {                               \
  98              STGCALL1(awakenBlockedQueue,                               \
  99                       ((StgBlockingQueue *)closure)->blocking_queue);   \
 100         }
 101
 102
 103 /* -----------------------------------------------------------------------------
 104    Push an update frame on the stack.
 105    -------------------------------------------------------------------------- */
 106
 107 #if defined(PROFILING)
 108 #define PUSH_STD_CCCS(frame) frame->header.prof.ccs = CCCS
 109 #else
 110 #define PUSH_STD_CCCS(frame)
 111 #endif
 112
 113 extern DLL_IMPORT_DATA const StgPolyInfoTable Upd_frame_info;
 114
 115 #define PUSH_UPD_FRAME(target, Sp_offset)                       \
 116         {                                                       \
 117                 StgUpdateFrame *__frame;                        \
 118                 TICK_UPDF_PUSHED(target, GET_INFO((StgClosure*)target)); \
 119                 __frame = (StgUpdateFrame *)(Sp + (Sp_offset)) - 1; \
 120                 SET_INFO(__frame, (StgInfoTable *)&Upd_frame_info);   \
 121                 __frame->link = Su;                             \
 122                 __frame->updatee = (StgClosure *)(target);      \
 123                 PUSH_STD_CCCS(__frame);                         \
 124                 Su = __frame;                                   \
 125         }
 126
 127 /* -----------------------------------------------------------------------------
 128    Entering CAFs
 129
 130    When a CAF is first entered, it creates a black hole in the heap,
 131    and updates itself with an indirection to this new black hole.
 132
 133    We update the CAF with an indirection to a newly-allocated black
 134    hole in the heap.  We also set the blocking queue on the newly
 135    allocated black hole to be empty.
 136
 137    Why do we make a black hole in the heap when we enter a CAF?
 138
 139        - for a  generational garbage collector, which needs a fast
 140          test for whether an updatee is in an old generation or not
 141
 142        - for the parallel system, which can implement updates more
 143          easily if the updatee is always in the heap. (allegedly).
 144
 145    When debugging, we maintain a separate CAF list so we can tell when
 146    a CAF has been garbage collected.
 147    -------------------------------------------------------------------------- */
 148
 149 /* ToDo: only call newCAF when debugging. */
 150
 151 extern void newCAF(StgClosure*);
 152
 153 #define UPD_CAF(cafptr, bhptr)                                          \
 154   {                                                                     \
 155     LOCK_CLOSURE(cafptr);                                               \
 156     ((StgInd *)cafptr)->indirectee   = (StgClosure *)(bhptr);           \
 157     SET_INFO((StgInd *)cafptr,(const StgInfoTable*)&IND_STATIC_info);   \
 158     STGCALL1(newCAF,(StgClosure *)cafptr);                              \
 159   }
 160
 161 /* -----------------------------------------------------------------------------
 162    Update-related prototypes
 163    -------------------------------------------------------------------------- */
 164
 165 DLL_IMPORT_RTS extern STGFUN(Upd_frame_entry);
 166
 167 extern DLL_IMPORT_DATA const StgInfoTable PAP_info;
 168 DLL_IMPORT_RTS STGFUN(PAP_entry);
 169
 170 EXTFUN_RTS(stg_update_PAP);
 171
 172 extern DLL_IMPORT_DATA const StgInfoTable AP_UPD_info;
 173 DLL_IMPORT_RTS STGFUN(AP_UPD_entry);
 174
 175 extern DLL_IMPORT_DATA const StgInfoTable raise_info;
 176
 177 #endif /* UPDATES_H */