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<title>GNU Compiler Collection (GCC) Internals: Miscellaneous routines</title>
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<a name="Miscellaneous-routines"></a>
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<p>
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Previous: <a href="Exception-handling-routines.html#Exception-handling-routines" accesskey="p" rel="prev">Exception handling routines</a>, Up: <a href="Libgcc.html#Libgcc" accesskey="u" rel="up">Libgcc</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="Miscellaneous-runtime-library-routines"></a>
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<h3 class="section">4.6 Miscellaneous runtime library routines</h3>
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<a name="Cache-control-functions"></a>
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<h4 class="subsection">4.6.1 Cache control functions</h4>
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<dl>
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<dt><a name="index-_005f_005fclear_005fcache"></a>Runtime Function: <em>void</em> <strong>__clear_cache</strong> <em>(char *<var>beg</var>, char *<var>end</var>)</em></dt>
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<dd><p>This function clears the instruction cache between <var>beg</var> and <var>end</var>.
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</p></dd></dl>
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<a name="Split-stack-functions-and-variables"></a>
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<h4 class="subsection">4.6.2 Split stack functions and variables</h4>
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<dl>
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<dt><a name="index-_005f_005fsplitstack_005ffind"></a>Runtime Function: <em>void *</em> <strong>__splitstack_find</strong> <em>(void *<var>segment_arg</var>, void *<var>sp</var>, size_t <var>len</var>, void **<var>next_segment</var>, void **<var>next_sp</var>, void **<var>initial_sp</var>)</em></dt>
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<dd><p>When using <samp>-fsplit-stack</samp>, this call may be used to iterate
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over the stack segments. It may be called like this:
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</p><div class="smallexample">
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<pre class="smallexample"> void *next_segment = NULL;
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void *next_sp = NULL;
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void *initial_sp = NULL;
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void *stack;
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size_t stack_size;
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while ((stack = __splitstack_find (next_segment, next_sp,
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&stack_size, &next_segment,
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&next_sp, &initial_sp))
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!= NULL)
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{
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/* Stack segment starts at stack and is
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stack_size bytes long. */
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}
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</pre></div>
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<p>There is no way to iterate over the stack segments of a different
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thread. However, what is permitted is for one thread to call this
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with the <var>segment_arg</var> and <var>sp</var> arguments NULL, to pass
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<var>next_segment</var>, <var>next_sp</var>, and <var>initial_sp</var> to a different
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thread, and then to suspend one way or another. A different thread
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may run the subsequent <code>__splitstack_find</code> iterations. Of
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course, this will only work if the first thread is suspended while the
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second thread is calling <code>__splitstack_find</code>. If not, the second
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thread could be looking at the stack while it is changing, and
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anything could happen.
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</p></dd></dl>
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<dl>
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<dt><a name="index-_005f_005fmorestack_005fsegments"></a>Variable: <strong>__morestack_segments</strong></dt>
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<dt><a name="index-_005f_005fmorestack_005fcurrent_005fsegment"></a>Variable: <strong>__morestack_current_segment</strong></dt>
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<dt><a name="index-_005f_005fmorestack_005finitial_005fsp"></a>Variable: <strong>__morestack_initial_sp</strong></dt>
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<dd><p>Internal variables used by the <samp>-fsplit-stack</samp> implementation.
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</p></dd></dl>
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