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<title>GNU libgomp: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</title>

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<a name="Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses-1"></a>
<h3 class="section">4.8 Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</h3>

<p>This seems simple enough for PARALLEL blocks.  Create a private 
struct for communicating between the parent and subfunction.
In the parent, copy in values for scalar and &quot;small&quot; structs;
copy in addresses for others TREE_ADDRESSABLE types.  In the 
subfunction, copy the value into the local variable.
</p>
<p>It is not clear what to do with bare FOR or SECTION blocks.
The only thing I can figure is that we do something like:
</p>
<div class="smallexample">
<pre class="smallexample">#pragma omp for firstprivate(x) lastprivate(y)
for (int i = 0; i &lt; n; ++i)
  body;
</pre></div>

<p>which becomes
</p>
<div class="smallexample">
<pre class="smallexample">{
  int x = x, y;

  // for stuff

  if (i == n)
    y = y;
}
</pre></div>

<p>where the &quot;x=x&quot; and &quot;y=y&quot; assignments actually have different
uids for the two variables, i.e. not something you could write
directly in C.  Presumably this only makes sense if the &quot;outer&quot;
x and y are global variables.
</p>
<p>COPYPRIVATE would work the same way, except the structure 
broadcast would have to happen via SINGLE machinery instead.
</p>


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