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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Implement __builtin___clear_cache and lower to __clear_cache on ARM"
href="http://llvm.org/bugs/show_bug.cgi?id=19142">19142</a>
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<th>Summary</th>
<td>Implement __builtin___clear_cache and lower to __clear_cache on ARM
</td>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Backend: ARM
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>renato.golin@linaro.org
</td>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Android uses the GCC intrinsic __builtin___clear_cache described here:
<a href="http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html">http://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html</a>
To implement that in LLVM we'd have to add it in three steps:
1. Add support for clang to recognise __builtin___clear_cache and lower to some
intrinsic like @llvm.clear_cache
2. Add a LibCall to __clear_cache, but set it as noop by default (some targets
don't need it), and set it to __clear_cache on the targets that do support it.
3. Link @llvm.clear_cache to LibCall's __clear_cache.
As an extra, on ARM, would it be desired to lower the call to a sequence of
instructions (push r7, mov r7, #0xf0002, svc 0x0, pop r7), or is that a bit too
much optimisation?</pre>
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