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<body><span class="vcard"><a class="email" href="mailto:richard-llvm@metafoo.co.uk" title="Richard Smith <richard-llvm@metafoo.co.uk>"> <span class="fn">Richard Smith</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - incorrect loop optimization at O2"
href="http://llvm.org/bugs/show_bug.cgi?id=16602">bug 16602</a>
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<th>What</th>
<th>Removed</th>
<th>Added</th>
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<td style="text-align:right;">Status</td>
<td>REOPENED
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<td>RESOLVED
</td>
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<td style="text-align:right;">CC</td>
<td>
</td>
<td>richard-llvm@metafoo.co.uk
</td>
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<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>INVALID
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - incorrect loop optimization at O2"
href="http://llvm.org/bugs/show_bug.cgi?id=16602#c3">Comment # 3</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - incorrect loop optimization at O2"
href="http://llvm.org/bugs/show_bug.cgi?id=16602">bug 16602</a>
from <span class="vcard"><a class="email" href="mailto:richard-llvm@metafoo.co.uk" title="Richard Smith <richard-llvm@metafoo.co.uk>"> <span class="fn">Richard Smith</span></a>
</span></b>
<pre>(In reply to <a href="show_bug.cgi?id=16602#c2">comment #2</a>)
<span class="quote">> I can use global variables in this way if I don't care about race
> conditions.</span >
False. Your code has a data race, and so has undefined behavior.
<span class="quote">> The condition can be missed few times in the loop but eventually
> x will become 29 and the loop must exit.</span >
False. The store to 'x' in 'set_x' is not guaranteed to ever become visible to
'main'.</pre>
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