From 59b04b1fed0d4639fa16b7f3ec914190fe28042d Mon Sep 17 00:00:00 2001
From: Vesa Karvonen <vesa.a.j.k@gmail.com>
Date: Mon, 21 Aug 2023 10:04:57 +0300
Subject: [PATCH] Avoid allocation in no-op update

---
 src/kcas/kcas.ml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/kcas/kcas.ml b/src/kcas/kcas.ml
index 2fcd84e1..4c3c1285 100644
--- a/src/kcas/kcas.ml
+++ b/src/kcas/kcas.ml
@@ -784,7 +784,10 @@ module Xt = struct
     end
     else
       let current = state_r.after in
-      let state = State { state_r with after = f current } in
+      let after = f current in
+      let state =
+        if current == after then state else State { state_r with after }
+      in
       xt.cass <- Cas { loc; state; lt; gt; awaiters = [] };
       current