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 void unlockClosure(StgClosure *p, const StgInfoTable *info);
  22
  23 #if defined(THREADED_RTS)
  24
  25 /* -----------------------------------------------------------------------------
  26  * Locking/unlocking closures
  27  *
  28  * This is used primarily in the implementation of MVars.
  29  * -------------------------------------------------------------------------- */
  30
  31 #define SPIN_COUNT 4000
  32
  33 // We want a callable copy of lockClosure() so that we can refer to it
  34 // from .cmm files compiled using the native codegen.
  35 EXTERN_INLINE StgInfoTable *lockClosure(StgClosure *p)
  36 {
  37     StgWord info;
  38     do {
  39         nat i = 0;
  40         do {
  41             info = xchg((P_)(void *)&p->header.info, (W_)&stg_WHITEHOLE_info);
  42             if (info != (W_)&stg_WHITEHOLE_info) return (StgInfoTable *)info;
  43         } while (++i < SPIN_COUNT);
  44         yieldThread();
  45     } while (1);
  46 }
  47
  48 EXTERN_INLINE void unlockClosure(StgClosure *p, const StgInfoTable *info)
  49 {
  50     // This is a strictly ordered write, so we need a write_barrier():
  51     write_barrier();
  52     p->header.info = info;
  53 }
  54
  55 #else /* !THREADED_RTS */
  56
  57 EXTERN_INLINE StgInfoTable *
  58 lockClosure(StgClosure *p)
  59 { return (StgInfoTable *)p->header.info; }
  60
  61 EXTERN_INLINE void
  62 unlockClosure(StgClosure *p STG_UNUSED, const StgInfoTable *info STG_UNUSED)
  63 { /* nothing */ }
  64
  65 #endif /* THREADED_RTS */
  66
  67 // Handy specialised versions of lockClosure()/unlockClosure()
  68 EXTERN_INLINE void lockTSO(StgTSO *tso);
  69 EXTERN_INLINE void lockTSO(StgTSO *tso)
  70 { lockClosure((StgClosure *)tso); }
  71
  72 EXTERN_INLINE void unlockTSO(StgTSO *tso);
  73 EXTERN_INLINE void unlockTSO(StgTSO *tso)
  74 { unlockClosure((StgClosure*)tso, (const StgInfoTable *)&stg_TSO_info); }
  75
  76 #endif /* CMINUSMINUS */
  77
  78 #endif /* RTS_STORAGE_SMPCLOSUREOPS_H */