X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;ds=sidebyside;f=rts%2FSparks.c;h=571529afbbc31b6f8d7c2e366f4b7635b754dde2;hb=65914a2cb71caf01655b16a75b283871e2482041;hp=e7273f3ed0167ff1bf7d16daaef2328759f35097;hpb=2b16fa4791b08b02df8461f3b79d0e44d72d0960;p=ghc-hetmet.git

diff --git a/rts/Sparks.c b/rts/Sparks.c
index e7273f3..571529a 100644
--- a/rts/Sparks.c
+++ b/rts/Sparks.c
@@ -202,10 +202,12 @@ steal(SparkPool *deque)
   StgClosurePtr stolen;
   StgWord b,t; 
 
-  ASSERT_SPARK_POOL_INVARIANTS(deque); 
+// Can't do this on someone else's spark pool:
+// ASSERT_SPARK_POOL_INVARIANTS(deque); 
 
   b = deque->bottom;
   t = deque->top;
+
   if (b - t <= 0 ) { 
     return NULL; /* already looks empty, abort */
   }
@@ -222,7 +224,9 @@ steal(SparkPool *deque)
       return NULL;
   }  /* else: OK, top has been incremented by the cas call */
 
-  ASSERT_SPARK_POOL_INVARIANTS(deque); 
+// Can't do this on someone else's spark pool:
+// ASSERT_SPARK_POOL_INVARIANTS(deque); 
+
   /* return stolen element */
   return stolen;
 }
@@ -389,6 +393,12 @@ pruneSparkQueue (evac_fn evac, void *user, Capability *cap)
     
     pool = cap->sparks;
     
+    // it is possible that top > bottom, indicating an empty pool.  We
+    // fix that here; this is only necessary because the loop below
+    // assumes it.
+    if (pool->top > pool->bottom)
+        pool->top = pool->bottom;
+
     // Take this opportunity to reset top/bottom modulo the size of
     // the array, to avoid overflow.  This is only possible because no
     // stealing is happening during GC.