Remove origin arguments from write barrier functionswip/nonmoving-gc

Write barriers push old values of updated field, e.g. when we have

    *q = p;

we do

    updateRemembSetPushClosure(*q, q);
    *q = p;

Here the second argument ("origin") is not useful because by the time we
do the update we invalidate "origin" (`q` is no longer origin of old
`*q`).

In general it doesn't make sense to record origins in write barriers so
we remove all origin arguments from write barriers.

Fixes #170.

1 files changed, 1 insertions, 3 deletions

diff --git a/rts/Threads.c b/rts/Threads.c
index 33cf907633..408304a6a6 100644
--- a/rts/Threads.c
+++ b/rts/Threads.c
@@ -717,9 +717,7 @@ threadStackUnderflow (Capability *cap, StgTSO *tso)
             // necessarily form a full closure so we need to handle them
             // specially.
             for (unsigned int i = 0; i < retvals; i++) {
-                updateRemembSetPushClosure(cap,
-                                         (StgClosure *) old_stack->sp[i],
-                                         NULL);
+                updateRemembSetPushClosure(cap, (StgClosure *) old_stack->sp[i]);
             }
         }