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<h4 class="subsection">6.60.3 MeP Pragmas</h4>
<dl>
<dt><code>custom io_volatile (on|off)</code><dd><a name="index-pragma_002c-custom-io_005fvolatile-4162"></a>Overrides the command-line option <code>-mio-volatile</code> for the current
file. Note that for compatibility with future GCC releases, this
option should only be used once before any <code>io</code> variables in each
file.
<br><dt><code>GCC coprocessor available </code><var>registers</var><dd><a name="index-pragma_002c-coprocessor-available-4163"></a>Specifies which coprocessor registers are available to the register
allocator. <var>registers</var> may be a single register, register range
separated by ellipses, or comma-separated list of those. Example:
<pre class="smallexample"> #pragma GCC coprocessor available $c0...$c10, $c28
</pre>
<br><dt><code>GCC coprocessor call_saved </code><var>registers</var><dd><a name="index-pragma_002c-coprocessor-call_005fsaved-4164"></a>Specifies which coprocessor registers are to be saved and restored by
any function using them. <var>registers</var> may be a single register,
register range separated by ellipses, or comma-separated list of
those. Example:
<pre class="smallexample"> #pragma GCC coprocessor call_saved $c4...$c6, $c31
</pre>
<br><dt><code>GCC coprocessor subclass '(A|B|C|D)' = </code><var>registers</var><dd><a name="index-pragma_002c-coprocessor-subclass-4165"></a>Creates and defines a register class. These register classes can be
used by inline <code>asm</code> constructs. <var>registers</var> may be a single
register, register range separated by ellipses, or comma-separated
list of those. Example:
<pre class="smallexample"> #pragma GCC coprocessor subclass 'B' = $c2, $c4, $c6
asm ("cpfoo %0" : "=B" (x));
</pre>
<br><dt><code>GCC disinterrupt </code><var>name</var><code> , </code><var>name</var><code> ...</code><dd><a name="index-pragma_002c-disinterrupt-4166"></a>For the named functions, the compiler adds code to disable interrupts
for the duration of those functions. If any functions so named
are not encountered in the source, a warning is emitted that the pragma is
not used. Examples:
<pre class="smallexample"> #pragma disinterrupt foo
#pragma disinterrupt bar, grill
int foo () { ... }
</pre>
<br><dt><code>GCC call </code><var>name</var><code> , </code><var>name</var><code> ...</code><dd><a name="index-pragma_002c-call-4167"></a>For the named functions, the compiler always uses a register-indirect
call model when calling the named functions. Examples:
<pre class="smallexample"> extern int foo ();
#pragma call foo
</pre>
</dl>
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