LWG2130 Missing ordering constraints

Author: jwakely

source/atomics.tex

@@ -289,11 +289,19 @@
 \textit{A} or a later modification of \textit{M} in its modification order.
 
 \pnum
-For atomic operations \textit{A} and \textit{B} on an atomic object \textit{M}, if there
-are \tcode{memory_order_seq_cst} fences \tcode{X} and \tcode{Y} such that \textit{A} is
-sequenced before \textit{X}, \textit{Y} is sequenced before \textit{B}, and \textit{X}
-precedes \textit{Y} in \textit{S}, then \textit{B} occurs later than \textit{A} in the
-modification order of \textit{M}.
+For atomic modifications \textit{A} and \textit{B} of an atomic object \textit{M},
+\textit{B} occurs later than \textit{A} in the modification order of \textit{M} if:
+
+\begin{itemize}
+\item there is a \tcode{memory_order_seq_cst} fence \textit{X} such that \textit{A}
+is sequenced before \textit{X}, and \textit{X} precedes \textit{B} in \textit{S}, or
+\item there is a \tcode{memory_order_seq_cst} fence \textit{Y} such that \textit{Y}
+is sequenced before \textit{B}, and \textit{A} precedes \textit{Y} in \textit{S}, or
+\item there are \tcode{memory_order_seq_cst} fences \textit{X} and \textit{Y} such that \textit{A}
+is sequenced before \textit{X}, \textit{Y} is sequenced before \textit{B},
+and \textit{X} precedes \textit{Y} in \textit{S}.
+\end{itemize}
+
 
 \pnum
 \enternote \tcode{memory_order_seq_cst} ensures sequential consistency only for a