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<title>Using the GNU Compiler Collection (GCC): SH Built-in Functions</title>
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<a name="SH-Built_002din-Functions"></a>
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Next: <a href="SPARC-VIS-Built_002din-Functions.html#SPARC-VIS-Built_002din-Functions" accesskey="n" rel="next">SPARC VIS Built-in Functions</a>, Previous: <a href="S_002f390-System-z-Built_002din-Functions.html#S_002f390-System-z-Built_002din-Functions" accesskey="p" rel="prev">S/390 System z Built-in Functions</a>, Up: <a href="Target-Builtins.html#Target-Builtins" accesskey="u" rel="up">Target Builtins</a> [<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="SH-Built_002din-Functions-1"></a>
<h4 class="subsection">6.59.25 SH Built-in Functions</h4>
<p>The following built-in functions are supported on the SH1, SH2, SH3 and SH4
families of processors:
</p>
<dl>
<dt><a name="index-_005f_005fbuiltin_005fset_005fthread_005fpointer"></a>Built-in Function: <em>void</em> <strong>__builtin_set_thread_pointer</strong> <em>(void *<var>ptr</var>)</em></dt>
<dd><p>Sets the ‘<samp>GBR</samp>’ register to the specified value <var>ptr</var>. This is usually
used by system code that manages threads and execution contexts. The compiler
normally does not generate code that modifies the contents of ‘<samp>GBR</samp>’ and
thus the value is preserved across function calls. Changing the ‘<samp>GBR</samp>’
value in user code must be done with caution, since the compiler might use
‘<samp>GBR</samp>’ in order to access thread local variables.
</p>
</dd></dl>
<dl>
<dt><a name="index-_005f_005fbuiltin_005fthread_005fpointer"></a>Built-in Function: <em>void *</em> <strong>__builtin_thread_pointer</strong> <em>(void)</em></dt>
<dd><p>Returns the value that is currently set in the ‘<samp>GBR</samp>’ register.
Memory loads and stores that use the thread pointer as a base address are
turned into ‘<samp>GBR</samp>’ based displacement loads and stores, if possible.
For example:
</p><div class="smallexample">
<pre class="smallexample">struct my_tcb
{
int a, b, c, d, e;
};
int get_tcb_value (void)
{
// Generate ‘<samp>mov.l @(8,gbr),r0</samp>’ instruction
return ((my_tcb*)__builtin_thread_pointer ())->c;
}
</pre></div>
</dd></dl>
<dl>
<dt><a name="index-_005f_005fbuiltin_005fsh_005fget_005ffpscr"></a>Built-in Function: <em>unsigned int</em> <strong>__builtin_sh_get_fpscr</strong> <em>(void)</em></dt>
<dd><p>Returns the value that is currently set in the ‘<samp>FPSCR</samp>’ register.
</p></dd></dl>
<dl>
<dt><a name="index-_005f_005fbuiltin_005fsh_005fset_005ffpscr"></a>Built-in Function: <em>void</em> <strong>__builtin_sh_set_fpscr</strong> <em>(unsigned int <var>val</var>)</em></dt>
<dd><p>Sets the ‘<samp>FPSCR</samp>’ register to the specified value <var>val</var>, while
preserving the current values of the FR, SZ and PR bits.
</p></dd></dl>
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