[Guile-commits] 236/423: whippet: avoid an atomic load when visiting already-marked objects

[Andy Wingo]

wingo pushed a commit to branch wip-whippet
in repository guile.

commit ff1e1b1d443173e3b5c8b1c161c85319396a7cc1
Author: Andy Wingo <wi...@igalia.com>
AuthorDate: Wed Jul 10 11:47:15 2024 +0200

    whippet: avoid an atomic load when visiting already-marked objects
---
 src/whippet.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/whippet.c b/src/whippet.c
index af9b3dbd4..9674560c2 100644
--- a/src/whippet.c
+++ b/src/whippet.c
@@ -678,7 +678,8 @@ static inline int trace_edge(struct gc_heap *heap, struct 
gc_edge edge) {
   struct gc_ref ref = gc_edge_ref(edge);
   int is_new = do_trace(heap, edge, ref);
 
-  if (GC_UNLIKELY(atomic_load_explicit(&heap->check_pending_ephemerons,
+  if (is_new &&
+      GC_UNLIKELY(atomic_load_explicit(&heap->check_pending_ephemerons,
                                        memory_order_relaxed)))
     gc_resolve_pending_ephemerons(ref, heap);