*p /= 2
*p += i
</pre>

<p>
If <code>i</code> and <code>*p</code> start equal to 2,
the original code does <code>*p = 3</code>,
so a racing thread can read only 2 or 3 from <code>*p</code>.
The rewritten code does <code>*p = 1</code> and then <code>*p = 3</code>,
allowing a racing thread to read 1 as well.
</p>

<p>
Note that all these optimizations are permitted in C/C++ compilers:

of a <a href="#Function_declarations">function declaration</a>
or <a href="#Function_literals">function literal</a> reserves
storage for a named variable.

Calling the built-in function <a href="#Allocation"><code>new</code></a>
or taking the address of a <a href="#Composite_literals">composite literal</a>
allocates storage for a variable at run time.
Such an anonymous variable is referred to via a (possibly implicit)

of a <a href="#Function_declarations">function declaration</a>
or <a href="#Function_literals">function literal</a> reserves
storage for a named variable.

Calling the built-in function <a href="#Allocation"><code>new</code></a>
or taking the address of a <a href="#Composite_literals">composite literal</a>
allocates storage for a variable at run time.
Such an anonymous variable is referred to via a (possibly implicit)