From: Olivier Dion <odion@efficios.com>
Date: Thu, 21 Nov 2024 16:54:55 +0000 (-0500)
Subject: Document cmm_cast_volatile
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=031ece570138435e3438166ee49b13b574bce25a;p=userspace-rcu.git

Document cmm_cast_volatile

Change-Id: I3ce8df69a967b3bdaf940c4db06fd775e5b9eccb
Signed-off-by: Olivier Dion <odion@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/include/urcu/compiler.h b/include/urcu/compiler.h
index 6254252..e027c13 100644
--- a/include/urcu/compiler.h
+++ b/include/urcu/compiler.h
@@ -193,6 +193,13 @@
 
 /*
  * Helper to add the volatile qualifier to a pointer.
+ *
+ * This is used to enforce volatile accesses even when using atomic
+ * builtins. Indeed, C11 atomic operations all work on volatile memory
+ * accesses, but this is not documented for compiler atomic builtins.
+ *
+ * This could prevent certain classes of optimization from the compiler such
+ * as load/store fusing.
  */
 #if defined __cplusplus
 template <typename T>