includes/rts/storage/SMPClosureOps.h

   1 /* ----------------------------------------------------------------------------
   2  *
   3  * (c) The GHC Team, 2005
   4  *
   5  * Macros for THREADED_RTS support
   6  *
   7  * -------------------------------------------------------------------------- */
   8
   9 #ifndef RTS_STORAGE_SMPCLOSUREOPS_H
  10 #define RTS_STORAGE_SMPCLOSUREOPS_H
  11
  12 #ifdef CMINUSMINUS
  13
  14 #define unlockClosure(ptr,info)                 \
  15     prim %write_barrier() [];                   \
  16     StgHeader_info(ptr) = info;
  17
  18 #else
  19
  20 EXTERN_INLINE StgInfoTable *lockClosure(StgClosure *p);
  21 EXTERN_INLINE StgInfoTable *tryLockClosure(StgClosure *p);
  22 EXTERN_INLINE void unlockClosure(StgClosure *p, const StgInfoTable *info);
  23
  24 #if defined(THREADED_RTS)
  25
  26 /* -----------------------------------------------------------------------------
  27  * Locking/unlocking closures
  28  *
  29  * This is used primarily in the implementation of MVars.
  30  * -------------------------------------------------------------------------- */
  31
  32 // We want a callable copy of lockClosure() so that we can refer to it
  33 // from .cmm files compiled using the native codegen.
  34 EXTERN_INLINE StgInfoTable *lockClosure(StgClosure *p)
  35 {
  36     StgWord info;
  37     do {
  38         nat i = 0;
  39         do {
  40             info = xchg((P_)(void *)&p->header.info, (W_)&stg_WHITEHOLE_info);
  41             if (info != (W_)&stg_WHITEHOLE_info) return (StgInfoTable *)info;
  42         } while (++i < SPIN_COUNT);
  43         yieldThread();
  44     } while (1);
  45 }
  46
  47 EXTERN_INLINE StgInfoTable *tryLockClosure(StgClosure *p)
  48 {
  49     StgWord info;
  50     info = xchg((P_)(void *)&p->header.info, (W_)&stg_WHITEHOLE_info);
  51     if (info != (W_)&stg_WHITEHOLE_info) {
  52         return (StgInfoTable *)info;
  53     } else {
  54         return NULL;
  55     }
  56 }
  57
  58 #else /* !THREADED_RTS */
  59
  60 EXTERN_INLINE StgInfoTable *
  61 lockClosure(StgClosure *p)
  62 { return (StgInfoTable *)p->header.info; }
  63
  64 EXTERN_INLINE StgInfoTable *
  65 tryLockClosure(StgClosure *p)
  66 { return (StgInfoTable *)p->header.info; }
  67
  68 #endif /* THREADED_RTS */
  69
  70 EXTERN_INLINE void unlockClosure(StgClosure *p, const StgInfoTable *info)
  71 {
  72     // This is a strictly ordered write, so we need a write_barrier():
  73     write_barrier();
  74     p->header.info = info;
  75 }
  76
  77 // Handy specialised versions of lockClosure()/unlockClosure()
  78 EXTERN_INLINE void lockTSO(StgTSO *tso);
  79 EXTERN_INLINE void lockTSO(StgTSO *tso)
  80 { lockClosure((StgClosure *)tso); }
  81
  82 EXTERN_INLINE void unlockTSO(StgTSO *tso);
  83 EXTERN_INLINE void unlockTSO(StgTSO *tso)
  84 { unlockClosure((StgClosure*)tso, (const StgInfoTable *)&stg_TSO_info); }
  85
  86 #endif /* CMINUSMINUS */
  87
  88 #endif /* RTS_STORAGE_SMPCLOSUREOPS_H */