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<h3 class="section">4.6 Miscellaneous runtime library routines</h3>
<h4 class="subsection">4.6.1 Cache control functions</h4>
<div class="defun">
— Runtime Function: void <b>__clear_cache</b> (<var>char *beg, char *end</var>)<var><a name="index-g_t_005f_005fclear_005fcache-1657"></a></var><br>
<blockquote><p>This function clears the instruction cache between <var>beg</var> and <var>end</var>.
</p></blockquote></div>
<h4 class="subsection">4.6.2 Split stack functions and variables</h4>
<div class="defun">
— Runtime Function: void * <b>__splitstack_find</b> (<var>void *segment_arg, void *sp, size_t len, void **next_segment, void **next_sp, void **initial_sp</var>)<var><a name="index-g_t_005f_005fsplitstack_005ffind-1658"></a></var><br>
<blockquote><p>When using <samp><span class="option">-fsplit-stack</span></samp>, this call may be used to iterate
over the stack segments. It may be called like this:
<pre class="smallexample"> void *next_segment = NULL;
void *next_sp = NULL;
void *initial_sp = NULL;
void *stack;
size_t stack_size;
while ((stack = __splitstack_find (next_segment, next_sp,
&stack_size, &next_segment,
&next_sp, &initial_sp))
!= NULL)
{
/* Stack segment starts at stack and is
stack_size bytes long. */
}
</pre>
<p>There is no way to iterate over the stack segments of a different
thread. However, what is permitted is for one thread to call this
with the <var>segment_arg</var> and <var>sp</var> arguments NULL, to pass
<var>next_segment</var>, <var>next_sp</var>, and <var>initial_sp</var> to a different
thread, and then to suspend one way or another. A different thread
may run the subsequent <code>__splitstack_find</code> iterations. Of
course, this will only work if the first thread is suspended while the
second thread is calling <code>__splitstack_find</code>. If not, the second
thread could be looking at the stack while it is changing, and
anything could happen.
</p></blockquote></div>
<div class="defun">
— Variable: <b>__morestack_segments</b><var><a name="index-g_t_005f_005fmorestack_005fsegments-1659"></a></var><br>
— Variable: <b>__morestack_current_segment</b><var><a name="index-g_t_005f_005fmorestack_005fcurrent_005fsegment-1660"></a></var><br>
— Variable: <b>__morestack_initial_sp</b><var><a name="index-g_t_005f_005fmorestack_005finitial_005fsp-1661"></a></var><br>
<blockquote><p>Internal variables used by the <samp><span class="option">-fsplit-stack</span></samp> implementation.
</p></blockquote></div>
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