-INLINE_HEADER void
-unlockClosure(StgClosure *p, const StgInfoTable *info)
-{
- // This is a strictly ordered write, so we need a write_barrier():
- write_barrier();
- p->header.info = info;
-}
-
-/* -----------------------------------------------------------------------------
- * Spin locks
- *
- * These are simple spin-only locks as opposed to Mutexes which
- * probably spin for a while before blocking in the kernel. We use
- * these when we are sure that all our threads are actively running on
- * a CPU, eg. in the GC.
- *
- * TODO: measure whether we really need these, or whether Mutexes
- * would do (and be a bit safer if a CPU becomes loaded).
- * -------------------------------------------------------------------------- */
-
-#if defined(DEBUG)
-typedef struct StgSync_
-{
- StgWord32 lock;
- StgWord64 spin; // DEBUG version counts how much it spins
-} StgSync;
+EXTERN_INLINE void
+load_load_barrier(void) {
+#if i386_HOST_ARCH
+ __asm__ __volatile__ ("" : : : "memory");
+#elif x86_64_HOST_ARCH
+ __asm__ __volatile__ ("" : : : "memory");
+#elif powerpc_HOST_ARCH
+ __asm__ __volatile__ ("lwsync" : : : "memory");
+#elif sparc_HOST_ARCH
+ /* Sparc in TSO mode does not require write/write barriers. */
+ __asm__ __volatile__ ("" : : : "memory");
+#elif !defined(WITHSMP)
+ return;