ghc/includes/Updates.h

   1 /* -----------------------------------------------------------------------------
   2  *
   3  * (c) The GHC Team, 1998-2004
   4  *
   5  * Performing updates.
   6  *
   7  * ---------------------------------------------------------------------------*/
   8
   9 #ifndef UPDATES_H
  10 #define UPDATES_H
  11
  12 /* -----------------------------------------------------------------------------
  13    Updates
  14
  15    We have two layers of update macros.  The top layer, UPD_IND() and
  16    friends perform all the work of an update.  In detail:
  17
  18       - if the closure being updated is a blocking queue, then all the
  19         threads waiting on the blocking queue are updated.
  20
  21       - then the lower level updateWithIndirection() macro is invoked
  22         to actually replace the closure with an indirection (see below).
  23
  24    -------------------------------------------------------------------------- */
  25
  26 #ifdef TICKY_TICKY
  27 # define UPD_IND(updclosure, heapptr) \
  28    UPD_PERM_IND(updclosure,heapptr)
  29 # define UPD_SPEC_IND(updclosure, ind_info, heapptr, and_then) \
  30    UPD_PERM_IND(updclosure,heapptr); and_then
  31 #else
  32 #  define SEMI ;
  33 # define UPD_IND(updclosure, heapptr) \
  34    UPD_REAL_IND(updclosure,INFO_PTR(stg_IND_info),heapptr,SEMI)
  35 # define UPD_SPEC_IND(updclosure, ind_info, heapptr, and_then) \
  36    UPD_REAL_IND(updclosure,ind_info,heapptr,and_then)
  37 #endif
  38
  39 /* These macros have to work in both C and C--, so here's the
  40  * impedence matching:
  41  */
  42 #ifdef CMINUSMINUS
  43 #define BLOCK_BEGIN
  44 #define BLOCK_END
  45 #define DECLARE_IPTR(info)  W_ info
  46 #define FCALL               foreign "C"
  47 #define INFO_PTR(info)      info
  48 #define ARG_PTR             "ptr"
  49 #else
  50 #define BLOCK_BEGIN         {
  51 #define BLOCK_END           }
  52 #define DECLARE_IPTR(info)  const StgInfoTable *(info)
  53 #define FCALL               /* nothing */
  54 #define INFO_PTR(info)      &info
  55 #define StgBlockingQueue_blocking_queue(closure) \
  56     (((StgBlockingQueue *)closure)->blocking_queue)
  57 #define ARG_PTR             /* nothing */
  58 #endif
  59
  60 /* UPD_IND actually does a PERM_IND if TICKY_TICKY is on;
  61    if you *really* need an IND use UPD_REAL_IND
  62  */
  63 #define UPD_REAL_IND(updclosure, ind_info, heapptr, and_then)   \
  64         BLOCK_BEGIN                                             \
  65         DECLARE_IPTR(info);                                     \
  66         info = GET_INFO(updclosure);                            \
  67         updateWithIndirection(ind_info,                         \
  68                               updclosure,                       \
  69                               heapptr,                          \
  70                               and_then);                        \
  71         BLOCK_END
  72
  73 #if defined(PROFILING) || defined(TICKY_TICKY)
  74 #define UPD_PERM_IND(updclosure, heapptr)       \
  75         BLOCK_BEGIN                             \
  76         updateWithPermIndirection(updclosure,   \
  77                                   heapptr);     \
  78         BLOCK_END
  79 #endif
  80
  81 #if defined(RTS_SUPPORTS_THREADS)
  82
  83 # ifdef TICKY_TICKY
  84 #  define UPD_IND_NOLOCK(updclosure, heapptr)   \
  85         BLOCK_BEGIN                             \
  86         updateWithPermIndirection(updclosure,   \
  87                                   heapptr);     \
  88         BLOCK_END
  89 # else
  90 #  define UPD_IND_NOLOCK(updclosure, heapptr)                   \
  91         BLOCK_BEGIN                                             \
  92         updateWithIndirection(INFO_PTR(stg_IND_info),           \
  93                               updclosure,                       \
  94                               heapptr,);                        \
  95         BLOCK_END
  96 # endif
  97
  98 #else
  99 #define UPD_IND_NOLOCK(updclosure,heapptr) UPD_IND(updclosure,heapptr)
 100 #endif
 101
 102 /* -----------------------------------------------------------------------------
 103    Awaken any threads waiting on a blocking queue (BLACKHOLE_BQ).
 104    -------------------------------------------------------------------------- */
 105
 106 #if defined(PAR)
 107
 108 /*
 109    In a parallel setup several types of closures might have a blocking queue:
 110      BLACKHOLE_BQ ... same as in the default concurrent setup; it will be
 111                       reawakened via calling UPD_IND on that closure after
 112                       having finished the computation of the graph
 113      FETCH_ME_BQ  ... a global indirection (FETCH_ME) may be entered by a
 114                       local TSO, turning it into a FETCH_ME_BQ; it will be
 115                       reawakened via calling processResume
 116      RBH          ... a revertible black hole may be entered by another
 117                       local TSO, putting it onto its blocking queue; since
 118                       RBHs only exist while the corresponding closure is in
 119                       transit, they will be reawakened via calling
 120                       convertToFetchMe (upon processing an ACK message)
 121
 122    In a parallel setup a blocking queue may contain 3 types of closures:
 123      TSO           ... as in the default concurrent setup
 124      BLOCKED_FETCH ... indicating that a TSO on another PE is waiting for
 125                        the result of the current computation
 126      CONSTR        ... an RBHSave closure (which contains data ripped out of
 127                        the closure to make room for a blocking queue; since
 128                        it only contains data we use the exisiting type of
 129                        a CONSTR closure); this closure is the end of a
 130                        blocking queue for an RBH closure; it only exists in
 131                        this kind of blocking queue and must be at the end
 132                        of the queue
 133 */
 134 extern void awakenBlockedQueue(StgBlockingQueueElement *q, StgClosure *node);
 135 #define DO_AWAKEN_BQ(bqe, node)  STGCALL2(awakenBlockedQueue, bqe, node);
 136
 137 #define AWAKEN_BQ(info,closure)                                         \
 138         if (info == &stg_BLACKHOLE_BQ_info ||               \
 139             info == &stg_FETCH_ME_BQ_info ||                \
 140             get_itbl(closure)->type == RBH) {                           \
 141                 DO_AWAKEN_BQ(((StgBlockingQueue *)closure)->blocking_queue, closure);                           \
 142         }
 143
 144 #elif defined(GRAN)
 145
 146 extern void awakenBlockedQueue(StgBlockingQueueElement *q, StgClosure *node);
 147 #define DO_AWAKEN_BQ(bq, node)  STGCALL2(awakenBlockedQueue, bq, node);
 148
 149 /* In GranSim we don't have FETCH_ME or FETCH_ME_BQ closures, so they are
 150    not checked. The rest of the code is the same as for GUM.
 151 */
 152 #define AWAKEN_BQ(info,closure)                                         \
 153         if (info == &stg_BLACKHOLE_BQ_info ||               \
 154             get_itbl(closure)->type == RBH) {                           \
 155                 DO_AWAKEN_BQ(((StgBlockingQueue *)closure)->blocking_queue, closure);                           \
 156         }
 157
 158 #endif /* GRAN || PAR */
 159
 160
 161 /* -----------------------------------------------------------------------------
 162    Updates: lower-level macros which update a closure with an
 163    indirection to another closure.
 164
 165    There are several variants of this code.
 166
 167        PROFILING:
 168    -------------------------------------------------------------------------- */
 169
 170 /* LDV profiling:
 171  * We call LDV_recordDead_FILL_SLOP_DYNAMIC(p1) regardless of the generation in
 172  * which p1 resides.
 173  *
 174  * Note:
 175  *   After all, we do *NOT* need to call LDV_RECORD_CREATE() for both IND and
 176  *   IND_OLDGEN closures because they are inherently used. But, it corrupts
 177  *   the invariants that every closure keeps its creation time in the profiling
 178  *  field. So, we call LDV_RECORD_CREATE().
 179  */
 180
 181 /* In the DEBUG case, we also zero out the slop of the old closure,
 182  * so that the sanity checker can tell where the next closure is.
 183  *
 184  * Two important invariants: we should never try to update a closure
 185  * to point to itself, and the closure being updated should not
 186  * already have been updated (the mutable list will get messed up
 187  * otherwise).
 188  *
 189  * NB. We do *not* do this in SMP mode, because when we have the
 190  * possibility of multiple threads entering the same closure, zeroing
 191  * the slop in one of the threads would have a disastrous effect on
 192  * the other (seen in the wild!).
 193  */
 194 #if !defined(DEBUG) || defined(SMP)
 195
 196 #define DEBUG_FILL_SLOP(p) /* nothing */
 197
 198 #else  /* DEBUG */
 199
 200 #ifdef CMINUSMINUS
 201
 202 #define DEBUG_FILL_SLOP(p)                                              \
 203   W_ inf;                                                               \
 204   W_ sz;                                                                \
 205   W_ i;                                                                 \
 206   inf = %GET_STD_INFO(p);                                               \
 207   if (%INFO_TYPE(inf) == HALF_W_(THUNK_SELECTOR)) {                     \
 208         StgThunk_payload(p,0) = 0;                                      \
 209   } else {                                                              \
 210     if (%INFO_TYPE(inf) != HALF_W_(BLACKHOLE)) {                        \
 211       if (%INFO_TYPE(inf) == HALF_W_(AP_STACK)) {                       \
 212           sz = StgAP_STACK_size(p) + BYTES_TO_WDS(SIZEOF_StgAP_STACK_NoHdr); \
 213       } else {                                                          \
 214           sz = TO_W_(%INFO_PTRS(inf)) + TO_W_(%INFO_NPTRS(inf));        \
 215       }                                                                 \
 216       i = 0;                                                            \
 217       for:                                                              \
 218         if (i < sz) {                                                   \
 219           StgThunk_payload(p,i) = 0;                                    \
 220           i = i + 1;                                                    \
 221           goto for;                                                     \
 222         }                                                               \
 223   } }
 224
 225 #else /* !CMINUSMINUS */
 226
 227 INLINE_HEADER void
 228 DEBUG_FILL_SLOP(StgClosure *p)
 229 {
 230     StgInfoTable *inf = get_itbl(p);
 231     nat i, sz;
 232
 233     switch (inf->type) {
 234     case BLACKHOLE:
 235         return;
 236     case AP_STACK:
 237         sz = ((StgAP_STACK *)p)->size + sizeofW(StgAP_STACK) - sizeofW(StgHeader);
 238         break;
 239     case THUNK_SELECTOR:
 240 #ifdef SMP
 241         ((StgSelector *)p)->selectee = 0;
 242 #endif
 243         return;
 244     default:
 245         sz = inf->layout.payload.ptrs + inf->layout.payload.nptrs;
 246         break;
 247     }
 248     for (i = 0; i < sz; i++) {
 249         ((StgThunk *)p)->payload[i] = 0;
 250     }
 251 }
 252
 253 #endif /* CMINUSMINUS */
 254 #endif /* DEBUG */
 255
 256 /* We have two versions of this macro (sadly), one for use in C-- code,
 257  * and the other for C.
 258  *
 259  * The and_then argument is a performance hack so that we can paste in
 260  * the continuation code directly.  It helps shave a couple of
 261  * instructions off the common case in the update code, which is
 262  * worthwhile (the update code is often part of the inner loop).
 263  * (except that gcc now appears to common up this code again and
 264  * invert the optimisation.  Grrrr --SDM).
 265  */
 266 #ifdef CMINUSMINUS
 267 #define generation(n) (W_[generations] + n*SIZEOF_generation)
 268 #define updateWithIndirection(ind_info, p1, p2, and_then)       \
 269     W_ bd;                                                      \
 270                                                                 \
 271 /*    ASSERT( p1 != p2 && !closure_IND(p1) );                   \
 272  */ LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(p1);                      \
 273 /*  foreign "C" cas(p1 "ptr", 0, stg_WHITEHOLE_info);           \
 274  */ bd = Bdescr(p1);                                            \
 275     if (bdescr_gen_no(bd) == 0 :: CInt) {                       \
 276       StgInd_indirectee(p1) = p2;                               \
 277       SET_INFO(p1, ind_info);                                   \
 278       LDV_RECORD_CREATE(p1);                                    \
 279       TICK_UPD_NEW_IND();                                       \
 280       and_then;                                                 \
 281     } else {                                                    \
 282       DEBUG_FILL_SLOP(p1);                                      \
 283       foreign "C" recordMutableGenLock(p1 "ptr",                \
 284                  generation(TO_W_(bdescr_gen_no(bd))) "ptr");   \
 285       StgInd_indirectee(p1) = p2;                               \
 286       SET_INFO(p1, stg_IND_OLDGEN_info);                        \
 287       LDV_RECORD_CREATE(p1);                                    \
 288       TICK_UPD_OLD_IND();                                       \
 289       and_then;                                                 \
 290   }
 291 #else
 292 #define updateWithIndirection(ind_info, p1, p2, and_then)               \
 293   {                                                                     \
 294     bdescr *bd;                                                         \
 295                                                                         \
 296     /* cas(p1, 0, &stg_WHITEHOLE_info); */                              \
 297     ASSERT( (P_)p1 != (P_)p2 && !closure_IND(p1) );                     \
 298     LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(p1);                              \
 299     bd = Bdescr((P_)p1);                                                \
 300     if (bd->gen_no == 0) {                                              \
 301       ((StgInd *)p1)->indirectee = p2;                                  \
 302       SET_INFO(p1, ind_info);                                           \
 303       LDV_RECORD_CREATE(p1);                                            \
 304       TICK_UPD_NEW_IND();                                               \
 305       and_then;                                                         \
 306     } else {                                                            \
 307       DEBUG_FILL_SLOP(p1);                                              \
 308       recordMutableGenLock(p1, &generations[bd->gen_no]);               \
 309       ((StgInd *)p1)->indirectee = p2;                                  \
 310       SET_INFO(p1, &stg_IND_OLDGEN_info);                               \
 311       TICK_UPD_OLD_IND();                                               \
 312       and_then;                                                         \
 313     }                                                                   \
 314   }
 315 #endif
 316
 317 /* The permanent indirection version isn't performance critical.  We
 318  * therefore use an inline C function instead of the C-- macro.
 319  */
 320 #ifndef CMINUSMINUS
 321 INLINE_HEADER void
 322 updateWithPermIndirection(StgClosure *p1,
 323                           StgClosure *p2)
 324 {
 325   bdescr *bd;
 326
 327   ASSERT( p1 != p2 && !closure_IND(p1) );
 328
 329   /*
 330    * @LDV profiling
 331    * Destroy the old closure.
 332    * Nb: LDV_* stuff cannot mix with ticky-ticky
 333    */
 334   LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(p1);
 335
 336   bd = Bdescr((P_)p1);
 337   if (bd->gen_no == 0) {
 338     ((StgInd *)p1)->indirectee = p2;
 339     SET_INFO(p1, &stg_IND_PERM_info);
 340     /*
 341      * @LDV profiling
 342      * We have just created a new closure.
 343      */
 344     LDV_RECORD_CREATE(p1);
 345     TICK_UPD_NEW_PERM_IND(p1);
 346   } else {
 347     recordMutableGenLock(p1, &generations[bd->gen_no]);
 348     ((StgInd *)p1)->indirectee = p2;
 349     SET_INFO(p1, &stg_IND_OLDGEN_PERM_info);
 350     /*
 351      * @LDV profiling
 352      * We have just created a new closure.
 353      */
 354     LDV_RECORD_CREATE(p1);
 355     TICK_UPD_OLD_PERM_IND();
 356   }
 357 }
 358 #endif
 359
 360 #endif /* UPDATES_H */