[project @ 2005-05-10 13:25:41 by simonmar]

[ghc-hetmet.git] / ghc / includes / SMP.h

diff --git a/ghc/includes/SMP.h b/ghc/includes/SMP.h
index e35b95b..86930f9 100644 (file)
--- a/ghc/includes/SMP.h
+++ b/ghc/includes/SMP.h
@@ -1,6 +1,6 @@
 /* ----------------------------------------------------------------------------
  *
- * (c) The GHC Team, 1999
+ * (c) The GHC Team, 2005
  *
  * Macros for SMP support
  *
@@ -23,60 +23,37 @@
 #error Build options incompatible with SMP.
 #endif
 
-/*
- * CMPXCHG - this instruction is the standard "test & set".  We use it
- * for locking closures in the thunk and blackhole entry code.  If the
- * closure is already locked, or has an unexpected info pointer
- * (because another thread is altering it in parallel), we just jump
- * to the new entry point.
- */
-#if defined(i386_HOST_ARCH) && defined(TABLES_NEXT_TO_CODE)
-#define CMPXCHG(p, cmp, new)                   \
-  __asm__ __volatile__ (                       \
-         "lock ; cmpxchg %1, %0\n"             \
-          "\tje 1f\n"                          \
-          "\tjmp *%%eax\n"                     \
-          "\t1:\n"                             \
-         : /* no outputs */                    \
-         : "m" (p), "r" (new), "r" (cmp)       \
-         )
-
 /* 
  * XCHG - the atomic exchange instruction.  Used for locking closures
  * during updates (see LOCK_CLOSURE below) and the MVar primops.
  */
-#define XCHG(reg, obj)                         \
-  __asm__ __volatile__ (                       \
-         "xchgl %1,%0"                         \
-          :"+r" (reg), "+m" (obj)              \
-          : /* no input-only operands */       \
-         )
-
+INLINE_HEADER StgWord
+xchg(StgPtr p, StgWord w)
+{
+    StgWord result;
+    result = w;
+    __asm__ __volatile__ (
+         "xchgl %1,%0"
+          :"+r" (result), "+m" (*p)
+          : /* no input-only operands */
+       );
+    return result;
+}
+
+INLINE_HEADER StgInfoTable *
+lockClosure(StgClosure *p)
+{
+    StgWord info;
+#if 0
+    do {
+       info = xchg((P_)&p->header.info, (W_)&stg_WHITEHOLE_info);
+       if (info != (W_)&stg_WHITEHOLE_info) return (StgInfoTable *)info;
+       yieldThread();
+    } while (1);
 #else
-#error SMP macros not defined for this architecture
+    info = p->header.info;
 #endif
-
-/*
- * LOCK_CLOSURE locks the specified closure, busy waiting for any
- * existing locks to be cleared.
- */
-#define LOCK_CLOSURE(c)                                        \
-  ({                                                   \
-    const StgInfoTable *__info;                                \
-    __info = &stg_WHITEHOLE_info;                      \
-    do {                                               \
-      XCHG(__info,((StgClosure *)(c))->header.info);   \
-    } while (__info == &stg_WHITEHOLE_info);           \
-    __info;                                            \
-  })
-
-#define LOCK_THUNK(__info)                             \
-  CMPXCHG(R1.cl->header.info, __info, &stg_WHITEHOLE_info);
-
-#else /* !SMP */
-
-#define LOCK_CLOSURE(c)     /* nothing */
-#define LOCK_THUNK(__info)  /* nothing */
+}
 
 #endif /* SMP */