execution: document additional mo_may_allow() optimization

mo_may_allow() actually performs two optimizations, not just the one
that is documented in its header.

diff --git a/execution.cc b/execution.cc
index 07866fe804a308054c716ae4eb92ba146cd53e15..e04b672a28d1a08e9e5991bacc3aa25826d3dbc9 100644 (file)
--- a/execution.cc
+++ b/execution.cc
@@ -1820,6 +1820,7 @@ bool ModelExecution::thin_air_constraint_may_allow(const ModelAction *writer, co
  * require compiler support):
  *
  *   If X --hb-> Y --mo-> Z, then X should not read from Z.
+ *   If X --hb-> Y, A --rf-> Y, and A --mo-> Z, then X should not read from Z.
  */
 bool ModelExecution::mo_may_allow(const ModelAction *writer, const ModelAction *reader)
 {