Use message-passing to implement throwTo in the RTS

This replaces some complicated locking schemes with message-passing
in the implementation of throwTo. The benefits are

 - previously it was impossible to guarantee that a throwTo from
   a thread running on one CPU to a thread running on another CPU
   would be noticed, and we had to rely on the GC to pick up these
   forgotten exceptions. This no longer happens.

 - the locking regime is simpler (though the code is about the same
   size)

 - threads can be unblocked from a blocked_exceptions queue without
   having to traverse the whole queue now.  It's a rare case, but
   replaces an O(n) operation with an O(1).

 - generally we move in the direction of sharing less between
   Capabilities (aka HECs), which will become important with other
   changes we have planned.

Also in this patch I replaced several STM-specific closure types with
a generic MUT_PRIM closure type, which allowed a lot of code in the GC
and other places to go away, hence the line-count reduction.  The
message-passing changes resulted in about a net zero line-count
difference.

1 files changed, 2 insertions, 42 deletions

diff --git a/rts/sm/Sanity.c b/rts/sm/Sanity.c
index 442fee1f7c..11d5424431 100644
--- a/rts/sm/Sanity.c
+++ b/rts/sm/Sanity.c
@@ -307,7 +307,8 @@ checkClosure( StgClosure* p )
     case IND_OLDGEN_PERM:
     case BLACKHOLE:
     case CAF_BLACKHOLE:
-    case STABLE_NAME:
+    case PRIM:
+    case MUT_PRIM:
     case MUT_VAR_CLEAN:
     case MUT_VAR_DIRTY:
     case CONSTR_STATIC:
@@ -416,39 +417,6 @@ checkClosure( StgClosure* p )
         checkTSO((StgTSO *)p);
         return tso_sizeW((StgTSO *)p);
 
-    case TVAR_WATCH_QUEUE:
-      {
-        StgTVarWatchQueue *wq = (StgTVarWatchQueue *)p;
-        ASSERT(LOOKS_LIKE_CLOSURE_PTR(wq->next_queue_entry));
-        ASSERT(LOOKS_LIKE_CLOSURE_PTR(wq->prev_queue_entry));
-        return sizeofW(StgTVarWatchQueue);
-      }
-
-    case INVARIANT_CHECK_QUEUE:
-      {
-        StgInvariantCheckQueue *q = (StgInvariantCheckQueue *)p;
-        ASSERT(LOOKS_LIKE_CLOSURE_PTR(q->invariant));
-        ASSERT(LOOKS_LIKE_CLOSURE_PTR(q->my_execution));
-        ASSERT(LOOKS_LIKE_CLOSURE_PTR(q->next_queue_entry));
-        return sizeofW(StgInvariantCheckQueue);
-      }
-
-    case ATOMIC_INVARIANT:
-      {
-        StgAtomicInvariant *invariant = (StgAtomicInvariant *)p;
-        ASSERT(LOOKS_LIKE_CLOSURE_PTR(invariant->code));
-        ASSERT(LOOKS_LIKE_CLOSURE_PTR(invariant->last_execution));
-        return sizeofW(StgAtomicInvariant);
-      }
-
-    case TVAR:
-      {
-        StgTVar *tv = (StgTVar *)p;
-        ASSERT(LOOKS_LIKE_CLOSURE_PTR(tv->current_value));
-        ASSERT(LOOKS_LIKE_CLOSURE_PTR(tv->first_watch_queue_entry));
-        return sizeofW(StgTVar);
-      }
-
     case TREC_CHUNK:
       {
         nat i;
@@ -461,14 +429,6 @@ checkClosure( StgClosure* p )
         }
         return sizeofW(StgTRecChunk);
       }
-
-    case TREC_HEADER:
-      {
-        StgTRecHeader *trec = (StgTRecHeader *)p;
-        ASSERT(LOOKS_LIKE_CLOSURE_PTR(trec -> enclosing_trec));
-        ASSERT(LOOKS_LIKE_CLOSURE_PTR(trec -> current_chunk));
-        return sizeofW(StgTRecHeader);
-      }
       
     default:
 	    barf("checkClosure (closure type %d)", info->type);