clarify no implicit dependencies when waiting on or signaling semapho…

…res (KhronosGroup#1231)

api/opencl_runtime_layer.asciidoc

@@ -13266,6 +13266,16 @@ events in _event_wait_list_ when {clEnqueueWaitSemaphoresKHR} returns.
 Waiting on the same binary semaphore twice without an interleaving signal
 may lead to undefined behavior.
 
+[NOTE]
+====
+When _command_queue_ is an out-of-order command-queue there are no implicit
+dependencies between the semaphore wait command and commands enqueued into the
+command-queue after the semaphore wait command.
+If such dependencies are required, applications may enqueue a command-queue
+barrier after the semaphore wait command, to explicitly add dependencies between
+the semaphore wait command and subsequent commands.
+====
+
 // refError
 
 {clEnqueueWaitSemaphoresKHR} returns {CL_SUCCESS} if the function is
@@ -13355,6 +13365,16 @@ events in _event_wait_list_ when {clEnqueueSignalSemaphoresKHR} returns.
 Signaling the same binary semaphore twice without an interleaving wait may
 lead to undefined behavior.
 
+[NOTE]
+====
+When _command_queue_ is an out-of-order command-queue there are no implicit
+dependencies between commands enqueued into the command-queue before the
+semaphore signal command and the semaphore signal command.
+If such dependencies are required, applications may enqueue a command-queue
+barrier before the semaphore signal command, to explicitly add dependencies between
+the preceding commands and the semaphore signal command.
+====
+
 // refError
 
 {clEnqueueSignalSemaphoresKHR} returns {CL_SUCCESS} if the function is