*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:

</p>

<ul>
<li>The <code>Read</code> method, deprecated in <code>math/rand</code>,
was not carried forward for <code>math/rand/v2</code>.
(It remains available in <code>math/rand</code>.)
The vast majority of calls to <code>Read</code> should use
<a href="/pkg/crypto/rand/#Read"><code>crypto/rand</code>’s <code>Read</code></a> instead.
Otherwise a custom <code>Read</code> can be constructed using the <code>Uint64</code> method.

<code>T</code>’s embedded interfaces.
</p>

<pre>
type Reader interface {
	Read(p []byte) (n int, err error)
	Close() error
}

type Writer interface {
	Write(p []byte) (n int, err error)
	Close() error
}

// ReadWriter's methods are Read, Write, and Close.
type ReadWriter interface {
	Reader  // includes methods of Reader in ReadWriter's method set

<li>
<code>LOCAL</code> = 128
<br>
This symbol is local to the dynamic shared object.
</li>
<li>
<code>TLSBSS</code> = 256
<br>
(For <code>DATA</code> and <code>GLOBL</code> items.)
Put this data in thread local storage.
</li>
<li>
<code>NOFRAME</code> = 512
<br>
(For <code>TEXT</code> items.)
Do not insert instructions to allocate a stack frame and save/restore the return

<code>E</code>
[<a href="#Go_1.18">Go 1.18</a>].
</p>

<pre>
type Reader interface {
	Read(p []byte) (n int, err error)
	Close() error
}

type Writer interface {
	Write(p []byte) (n int, err error)
	Close() error
}

// ReadWriter's methods are Read, Write, and Close.
type ReadWriter interface {
	Reader  // includes methods of Reader in ReadWriter's method set