</li>

<li>
<code>(R5, R6)</code>: Destination register pair.
</li>

</ul>

<h3 id="arm64">ARM64</h3>

<p>
<code>R18</code> is the "platform register", reserved on the Apple platform.
To prevent accidental misuse, the register is named <code>R18_PLATFORM</code>.
<code>R27</code> and <code>R28</code> are reserved by the compiler and linker.
<code>R29</code> is the frame pointer.
<code>R30</code> is the link register.

to disable optimizations that are invalid for Go.
</p>

<p>
Note that the prohibition on introducing data races
does not apply if the compiler can prove that the races
do not affect correct execution on the target platform.
For example, on essentially all CPUs, it is valid to rewrite
</p>

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

into:

<pre>
n := 0
local := *shared

	}
	h.Uid = int(sys.Uid)
	h.Gid = int(sys.Gid)
	if doNameLookups {
		// Best effort at populating Uname and Gname.
		// The os/user functions may fail for any number of reasons
		// (not implemented on that platform, cgo not enabled, etc).
		if u, ok := userMap.Load(h.Uid); ok {
			h.Uname = u.(string)
		} else if u, err := user.LookupId(strconv.Itoa(h.Uid)); err == nil {
			h.Uname = u.Username
			userMap.Store(h.Uid, h.Uname)
		}