Remove redundant code in dav1d_cdf_thread_unref()

Checking if the Dav1dRef pointer is non-zero and zeroing it is
already performed in dav1d_ref_dec(), no need to do it twice.

Also reorder code to enable tail call elimination.

1 files changed, 2 insertions, 3 deletions

diff --git a/src/cdf.c b/src/cdf.c
index 8ac87fe..e0f2132 100644
--- a/src/cdf.c
+++ b/src/cdf.c
@@ -4118,7 +4118,6 @@ void dav1d_cdf_thread_ref(CdfThreadContext *const dst,
 }
 
 void dav1d_cdf_thread_unref(CdfThreadContext *const cdf) {
-    if (cdf->ref)
-        dav1d_ref_dec(&cdf->ref);
-    memset(cdf, 0, sizeof(*cdf));
+    memset(&cdf->data, 0, sizeof(*cdf) - offsetof(CdfThreadContext, data));
+    dav1d_ref_dec(&cdf->ref);
 }