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Next: <a href="TI-C6X-Built_002din-Functions.html#TI-C6X-Built_002din-Functions" accesskey="n" rel="next">TI C6X Built-in Functions</a>, Previous: <a href="SPARC-VIS-Built_002din-Functions.html#SPARC-VIS-Built_002din-Functions" accesskey="p" rel="prev">SPARC VIS Built-in Functions</a>, Up: <a href="Target-Builtins.html#Target-Builtins" accesskey="u" rel="up">Target Builtins</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<a name="SPU-Built_002din-Functions-1"></a>
<h4 class="subsection">6.60.28 SPU Built-in Functions</h4>

<p>GCC provides extensions for the SPU processor as described in the
Sony/Toshiba/IBM SPU Language Extensions Specification.  GCC&rsquo;s
implementation differs in several ways.
</p>
<ul>
<li> The optional extension of specifying vector constants in parentheses is
not supported.

</li><li> A vector initializer requires no cast if the vector constant is of the
same type as the variable it is initializing.

</li><li> If <code>signed</code> or <code>unsigned</code> is omitted, the signedness of the
vector type is the default signedness of the base type.  The default
varies depending on the operating system, so a portable program should
always specify the signedness.

</li><li> By default, the keyword <code>__vector</code> is added. The macro
<code>vector</code> is defined in <code>&lt;spu_intrinsics.h&gt;</code> and can be
undefined.

</li><li> GCC allows using a <code>typedef</code> name as the type specifier for a
vector type.

</li><li> For C, overloaded functions are implemented with macros so the following
does not work:

<div class="smallexample">
<pre class="smallexample">  spu_add ((vector signed int){1, 2, 3, 4}, foo);
</pre></div>

<p>Since <code>spu_add</code> is a macro, the vector constant in the example
is treated as four separate arguments.  Wrap the entire argument in
parentheses for this to work.
</p>
</li><li> The extended version of <code>__builtin_expect</code> is not supported.

</li></ul>

<p><em>Note:</em> Only the interface described in the aforementioned
specification is supported. Internally, GCC uses built-in functions to
implement the required functionality, but these are not supported and
are subject to change without notice.
</p>


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