123 lines
5.1 KiB
HTML
123 lines
5.1 KiB
HTML
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<head>
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<title>GNU libgomp: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</title>
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<meta name="description" content="GNU libgomp: Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses">
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<link href="Library-Index.html#Library-Index" rel="index" title="Library Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="The-libgomp-ABI.html#The-libgomp-ABI" rel="up" title="The libgomp ABI">
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<link href="Implementing-REDUCTION-clause.html#Implementing-REDUCTION-clause" rel="next" title="Implementing REDUCTION clause">
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<link href="Implementing-PRIVATE-clause.html#Implementing-PRIVATE-clause" rel="prev" title="Implementing PRIVATE clause">
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<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
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<a name="Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses"></a>
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<div class="header">
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<p>
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Next: <a href="Implementing-REDUCTION-clause.html#Implementing-REDUCTION-clause" accesskey="n" rel="next">Implementing REDUCTION clause</a>, Previous: <a href="Implementing-PRIVATE-clause.html#Implementing-PRIVATE-clause" accesskey="p" rel="prev">Implementing PRIVATE clause</a>, Up: <a href="The-libgomp-ABI.html#The-libgomp-ABI" accesskey="u" rel="up">The libgomp ABI</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Library-Index.html#Library-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Implementing-FIRSTPRIVATE-LASTPRIVATE-COPYIN-and-COPYPRIVATE-clauses-1"></a>
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<h3 class="section">9.8 Implementing FIRSTPRIVATE LASTPRIVATE COPYIN and COPYPRIVATE clauses</h3>
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<p>This seems simple enough for PARALLEL blocks. Create a private
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struct for communicating between the parent and subfunction.
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In the parent, copy in values for scalar and "small" structs;
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copy in addresses for others TREE_ADDRESSABLE types. In the
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subfunction, copy the value into the local variable.
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</p>
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<p>It is not clear what to do with bare FOR or SECTION blocks.
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The only thing I can figure is that we do something like:
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</p>
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<div class="smallexample">
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<pre class="smallexample">#pragma omp for firstprivate(x) lastprivate(y)
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for (int i = 0; i < n; ++i)
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body;
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</pre></div>
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<p>which becomes
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</p>
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<div class="smallexample">
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<pre class="smallexample">{
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int x = x, y;
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// for stuff
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if (i == n)
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y = y;
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}
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</pre></div>
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<p>where the "x=x" and "y=y" assignments actually have different
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uids for the two variables, i.e. not something you could write
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directly in C. Presumably this only makes sense if the "outer"
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x and y are global variables.
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</p>
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<p>COPYPRIVATE would work the same way, except the structure
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broadcast would have to happen via SINGLE machinery instead.
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</p>
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</body>
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</html>
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