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<h3 class="section">6.32 Label Attributes</h3>
<p><a name="index-Label-Attributes-3308"></a>
GCC allows attributes to be set on C labels. See <a href="Attribute-Syntax.html#Attribute-Syntax">Attribute Syntax</a>, for
details of the exact syntax for using attributes. Other attributes are
available for functions (see <a href="Function-Attributes.html#Function-Attributes">Function Attributes</a>), variables
(see <a href="Variable-Attributes.html#Variable-Attributes">Variable Attributes</a>) and for types (see <a href="Type-Attributes.html#Type-Attributes">Type Attributes</a>).
<p>This example uses the <code>cold</code> label attribute to indicate the
<code>ErrorHandling</code> branch is unlikely to be taken and that the
<code>ErrorHandling</code> label is unused:
<pre class="smallexample">
asm goto ("some asm" : : : : NoError);
/* This branch (the fall-through from the asm) is less commonly used */
ErrorHandling:
__attribute__((cold, unused)); /* Semi-colon is required here */
printf("error\n");
return 0;
NoError:
printf("no error\n");
return 1;
</pre>
<dl>
<dt><code>unused</code><dd><a name="index-g_t_0040code_007bunused_007d-label-attribute-3309"></a>This feature is intended for program-generated code that may contain
unused labels, but which is compiled with <samp><span class="option">-Wall</span></samp>. It is
not normally appropriate to use in it human-written code, though it
could be useful in cases where the code that jumps to the label is
contained within an <code>#ifdef</code> conditional.
<br><dt><code>hot</code><dd><a name="index-g_t_0040code_007bhot_007d-label-attribute-3310"></a>The <code>hot</code> attribute on a label is used to inform the compiler that
the path following the label is more likely than paths that are not so
annotated. This attribute is used in cases where <code>__builtin_expect</code>
cannot be used, for instance with computed goto or <code>asm goto</code>.
<br><dt><code>cold</code><dd><a name="index-g_t_0040code_007bcold_007d-label-attribute-3311"></a>The <code>cold</code> attribute on labels is used to inform the compiler that
the path following the label is unlikely to be executed. This attribute
is used in cases where <code>__builtin_expect</code> cannot be used, for instance
with computed goto or <code>asm goto</code>.
</dl>
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