rts/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 #ifndef CMINUSMINUS
  13 #include "BeginPrivate.h"
  14 #endif
  15
  16 /* -----------------------------------------------------------------------------
  17    Updates
  18    -------------------------------------------------------------------------- */
  19
  20 /* LDV profiling:
  21  *   After all, we do *NOT* need to call LDV_RECORD_CREATE() for IND
  22  *   closures because they are inherently used. But, it corrupts
  23  *   the invariants that every closure keeps its creation time in the profiling
  24  *  field. So, we call LDV_RECORD_CREATE().
  25  */
  26
  27 /* We have two versions of this macro (sadly), one for use in C-- code,
  28  * and the other for C.
  29  *
  30  * The and_then argument is a performance hack so that we can paste in
  31  * the continuation code directly.  It helps shave a couple of
  32  * instructions off the common case in the update code, which is
  33  * worthwhile (the update code is often part of the inner loop).
  34  * (except that gcc now appears to common up this code again and
  35  * invert the optimisation.  Grrrr --SDM).
  36  */
  37 #ifdef CMINUSMINUS
  38
  39 #define updateWithIndirection(p1, p2, and_then) \
  40     W_ bd;                                                      \
  41                                                                 \
  42     OVERWRITING_CLOSURE(p1);                                    \
  43     StgInd_indirectee(p1) = p2;                                 \
  44     prim %write_barrier() [];                                   \
  45     SET_INFO(p1, stg_BLACKHOLE_info);                           \
  46     LDV_RECORD_CREATE(p1);                                      \
  47     bd = Bdescr(p1);                                            \
  48     if (bdescr_gen_no(bd) != 0 :: bits16) {                     \
  49       recordMutableCap(p1, TO_W_(bdescr_gen_no(bd)), R1);       \
  50       TICK_UPD_OLD_IND();                                       \
  51       and_then;                                                 \
  52     } else {                                                    \
  53       TICK_UPD_NEW_IND();                                       \
  54       and_then;                                                 \
  55   }
  56
  57 #else /* !CMINUSMINUS */
  58
  59 INLINE_HEADER void updateWithIndirection (Capability *cap,
  60                                           StgClosure *p1,
  61                                           StgClosure *p2)
  62 {
  63     bdescr *bd;
  64
  65     ASSERT( (P_)p1 != (P_)p2 );
  66     /* not necessarily true: ASSERT( !closure_IND(p1) ); */
  67     /* occurs in RaiseAsync.c:raiseAsync() */
  68     OVERWRITING_CLOSURE(p1);
  69     ((StgInd *)p1)->indirectee = p2;
  70     write_barrier();
  71     SET_INFO(p1, &stg_BLACKHOLE_info);
  72     LDV_RECORD_CREATE(p1);
  73     bd = Bdescr((StgPtr)p1);
  74     if (bd->gen_no != 0) {
  75         recordMutableCap(p1, cap, bd->gen_no);
  76         TICK_UPD_OLD_IND();
  77     } else {
  78         TICK_UPD_NEW_IND();
  79     }
  80 }
  81
  82 #endif /* CMINUSMINUS */
  83
  84 #ifndef CMINUSMINUS
  85 #include "EndPrivate.h"
  86 #endif
  87
  88 #endif /* UPDATES_H */