NonMoving: Prefetch segment header

2 files changed, 8 insertions, 2 deletions

diff --git a/rts/sm/NonMoving.h b/rts/sm/NonMoving.h
index d1624a494d..165c7b1dfd 100644
--- a/rts/sm/NonMoving.h
+++ b/rts/sm/NonMoving.h
@@ -202,13 +202,18 @@ INLINE_HEADER void *nonmovingSegmentGetBlock(struct NonmovingSegment *seg, nonmo
 
 // Get the segment which a closure resides in. Assumes that pointer points into
 // non-moving heap.
-INLINE_HEADER struct NonmovingSegment *nonmovingGetSegment(StgPtr p)
+INLINE_HEADER struct NonmovingSegment *nonmovingGetSegment_unchecked(StgPtr p)
 {
-    ASSERT(HEAP_ALLOCED_GC(p) && (Bdescr(p)->flags & BF_NONMOVING));
     const uintptr_t mask = ~NONMOVING_SEGMENT_MASK;
     return (struct NonmovingSegment *) (((uintptr_t) p) & mask);
 }
 
+INLINE_HEADER struct NonmovingSegment *nonmovingGetSegment(StgPtr p)
+{
+    ASSERT(HEAP_ALLOCED_GC(p) && (Bdescr(p)->flags & BF_NONMOVING));
+    return nonmovingGetSegment_unchecked(p);
+}
+
 INLINE_HEADER nonmoving_block_idx nonmovingGetBlockIdx(StgPtr p)
 {
     ASSERT(HEAP_ALLOCED_GC(p) && (Bdescr(p)->flags & BF_NONMOVING));
diff --git a/rts/sm/NonMovingMark.c b/rts/sm/NonMovingMark.c
index 201c8fc958..5e2a90209b 100644
--- a/rts/sm/NonMovingMark.c
+++ b/rts/sm/NonMovingMark.c
@@ -770,6 +770,7 @@ static MarkQueueEnt markQueuePop (MarkQueue *q)
         // MarkQueueEnt encoding always places the pointer to the object to be
         // marked first.
         prefetchForRead(&new.mark_closure.p->header.info);
+        prefetchForRead(&nonmovingGetSegment_unchecked((StgPtr) new.mark_closure.p)->block_size);
         q->prefetch_queue[i] = new;
         i = (i + 1) % MARK_PREFETCH_QUEUE_DEPTH;
     }