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<h4 class="subsection">6.54.3 MeP Pragmas</h4>

     <dl>
<dt><code>custom io_volatile (on|off)</code><dd><a name="index-pragma_002c-custom-io_005fvolatile-3123"></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-3124"></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="example">          #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-3125"></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="example">          #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-3126"></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="example">          #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-3127"></a>For the named functions, the compiler adds code to disable interrupts
for the duration of those functions.  Any functions so named, which
are not encountered in the source, cause a warning that the pragma was
not used.  Examples:

     <pre class="example">          #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-3128"></a>For the named functions, the compiler always uses a register-indirect
call model when calling the named functions.  Examples:

     <pre class="example">          extern int foo ();
          #pragma call foo
</pre>
     </dl>

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