ghc/includes/SMP.h

   1 /* ----------------------------------------------------------------------------
   2  * $Id: SMP.h,v 1.2 2001/02/08 14:36:21 simonmar Exp $
   3  *
   4  * (c) The GHC Team, 1999
   5  *
   6  * Macros for SMP support
   7  *
   8  * -------------------------------------------------------------------------- */
   9
  10 #ifndef SMP_H
  11 #define SMP_H
  12
  13 /* SMP is currently not compatible with the following options:
  14  *
  15  *      INTERPRETER
  16  *      PROFILING
  17  *      TICKY_TICKY
  18  *      and unregisterised builds.
  19  */
  20
  21 #if defined(SMP)
  22
  23 #if    defined(INTERPRETER) \
  24      || defined(PROFILING)  \
  25      || defined(TICKY_TICKY)
  26 #error Build options incompatible with SMP.
  27 #endif
  28
  29 /*
  30  * CMPXCHG - this instruction is the standard "test & set".  We use it
  31  * for locking closures in the thunk and blackhole entry code.  If the
  32  * closure is already locked, or has an unexpected info pointer
  33  * (because another thread is altering it in parallel), we just jump
  34  * to the new entry point.
  35  */
  36 #if defined(i386_TARGET_ARCH) && defined(TABLES_NEXT_TO_CODE)
  37 #define CMPXCHG(p, cmp, new)                    \
  38   __asm__ __volatile__ (                        \
  39           "lock ; cmpxchg %1, %0\n"             \
  40           "\tje 1f\n"                           \
  41           "\tjmp *%%eax\n"                      \
  42           "\t1:\n"                              \
  43           : /* no outputs */                    \
  44           : "m" (p), "r" (new), "r" (cmp)       \
  45           )
  46
  47 /*
  48  * XCHG - the atomic exchange instruction.  Used for locking closures
  49  * during updates (see LOCK_CLOSURE below) and the MVar primops.
  50  */
  51 #define XCHG(reg, obj)                          \
  52   __asm__ __volatile__ (                        \
  53           "xchgl %1,%0"                         \
  54           :"+r" (reg), "+m" (obj)               \
  55           : /* no input-only operands */        \
  56           )
  57
  58 #else
  59 #error SMP macros not defined for this architecture
  60 #endif
  61
  62 /*
  63  * LOCK_CLOSURE locks the specified closure, busy waiting for any
  64  * existing locks to be cleared.
  65  */
  66 #define LOCK_CLOSURE(c)                                 \
  67   ({                                                    \
  68     const StgInfoTable *__info;                         \
  69     __info = &stg_WHITEHOLE_info;                       \
  70     do {                                                \
  71       XCHG(__info,((StgClosure *)(c))->header.info);    \
  72     } while (__info == &stg_WHITEHOLE_info);            \
  73     __info;                                             \
  74   })
  75
  76 #define LOCK_THUNK(__info)                              \
  77   CMPXCHG(R1.cl->header.info, __info, &stg_WHITEHOLE_info);
  78
  79 #define ACQUIRE_LOCK(mutex) pthread_mutex_lock(mutex);
  80 #define RELEASE_LOCK(mutex) pthread_mutex_unlock(mutex);
  81
  82 #else /* !SMP */
  83
  84 #define LOCK_CLOSURE(c)     /* nothing */
  85 #define LOCK_THUNK(__info)  /* nothing */
  86 #define ACQUIRE_LOCK(mutex) /* nothing */
  87 #define RELEASE_LOCK(mutex) /* nothing */
  88
  89 #endif /* SMP */
  90
  91 #endif /* SMP_H */