<p>
Both the channel and the value expression are evaluated before communication
begins. Communication blocks until the send can proceed.
A send on an unbuffered channel can proceed if a receiver is ready.
A send on a buffered channel can proceed if there is room in the buffer.
A send on a closed channel proceeds by causing a <a href="#Run_time_panics">run-time panic</a>.
A send on a <code>nil</code> channel blocks forever.
</p>

n := 0
for i := 0; i < m; i++ {
	n += *shared
}
</pre>

into:

<pre>
n := 0
local := *shared
for i := 0; i < m; i++ {
	n += local
}
</pre>

<p>
provided it can be proved that <code>*shared</code> will not fault on access,
because the potential added read will not affect any existing concurrent reads or writes.
On the other hand, the rewrite would not be valid in a source-to-source translator.
</p>

are defined for all architectures: if the compiler doesn't generate it, it might not be there.
If you need to use a missing instruction, there are two ways to proceed.
One is to update the assembler to support that instruction, which is straightforward
but only worthwhile if it's likely the instruction will be used again.

<p>
Both the channel and the value expression are evaluated before communication
begins. Communication blocks until the send can proceed.
A send on an unbuffered channel can proceed if a receiver is ready.
A send on a buffered channel can proceed if there is room in the buffer.
A send on a closed channel proceeds by causing a <a href="#Run_time_panics">run-time panic</a>.
A send on a <code>nil</code> channel blocks forever.
</p>