[commit: ghc] wip/nonmoving-gc: rts: Always disable nonmoving write barrier if !THREADED (4a4251d)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/nonmoving-gc
Link       : http://ghc.haskell.org/trac/ghc/changeset/4a4251d90ebf525b71cc2bf4354acaf97ae902b1/ghc

>---------------------------------------------------------------

commit 4a4251d90ebf525b71cc2bf4354acaf97ae902b1
Author: Ben Gamari <ben at smart-cactus.org>
Date:   Tue Feb 5 16:39:51 2019 -0500

    rts: Always disable nonmoving write barrier if !THREADED


>---------------------------------------------------------------

4a4251d90ebf525b71cc2bf4354acaf97ae902b1
 includes/Cmm.h         | 5 +++++
 rts/sm/NonMovingMark.c | 2 ++
 rts/sm/NonMovingMark.h | 8 ++++++++
 3 files changed, 15 insertions(+)

diff --git a/includes/Cmm.h b/includes/Cmm.h
index bee0d6d..b844020 100644
--- a/includes/Cmm.h
+++ b/includes/Cmm.h
@@ -797,6 +797,11 @@
    Misc junk
    -------------------------------------------------------------------------- */
 
+#if !defined(THREADED_RTS)
+// This is also done in rts/NonMoving.h, but that isn't visible from C--
+#define nonmoving_write_barrier_enabled 0
+#endif
+
 #define NO_TREC                   stg_NO_TREC_closure
 #define END_TSO_QUEUE             stg_END_TSO_QUEUE_closure
 #define STM_AWOKEN                stg_STM_AWOKEN_closure
diff --git a/rts/sm/NonMovingMark.c b/rts/sm/NonMovingMark.c
index 5e67fec..9be320f 100644
--- a/rts/sm/NonMovingMark.c
+++ b/rts/sm/NonMovingMark.c
@@ -163,7 +163,9 @@ static Condition upd_rem_set_flushed_cond;
 /* Indicates to mutators that the write barrier must be respected. Set while
  * concurrent mark is running.
  */
+#if defined(THREADED_RTS)
 bool nonmoving_write_barrier_enabled = false;
+#endif
 
 /* Used to provide the current mark queue to the young generation
  * collector for scavenging.
diff --git a/rts/sm/NonMovingMark.h b/rts/sm/NonMovingMark.h
index 2281d07..b11c4fa 100644
--- a/rts/sm/NonMovingMark.h
+++ b/rts/sm/NonMovingMark.h
@@ -114,7 +114,15 @@ extern StgIndStatic *debug_caf_list_snapshot;
 
 extern MarkQueue *current_mark_queue;
 extern bdescr *upd_rem_set_block_list;
+
+#if defined(THREADED_RTS)
 extern bool nonmoving_write_barrier_enabled;
+#else
+// The write barrier is never needed if !THREADED since we don't perform
+// concurrent collection in this case.
+#define nonmoving_write_barrier_enabled 0
+#endif
+
 void nonmovingMarkInitUpdRemSet(void);
 
 void init_upd_rem_set(UpdRemSet *rset);