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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 - A Division by Zero does not generate a floating point exception when optimizations are enabled"
href="https://llvm.org/bugs/show_bug.cgi?id=23358">bug 23358</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
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<td style="text-align:right;">CC</td>
<td>
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<td>richard-llvm@metafoo.co.uk
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<td style="text-align:right;">Resolution</td>
<td>---
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<td>INVALID
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - A Division by Zero does not generate a floating point exception when optimizations are enabled"
href="https://llvm.org/bugs/show_bug.cgi?id=23358#c4">Comment # 4</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - A Division by Zero does not generate a floating point exception when optimizations are enabled"
href="https://llvm.org/bugs/show_bug.cgi?id=23358">bug 23358</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=23358#c3">comment #3</a>)
<span class="quote">> What I'm saying is that since I've been using clang, the clang definition of
> undefined behavior was to throw a floating point exception</span >
That is not correct. Clang does not define this particular undefined behavior,
and never did. It is the nature of undefined behavior that sometimes you'll see
it behaving in some predictable way, but that does not make it defined.
[In the original testcase, we are in fact preserving the two volatile loads of
l, and if they produce different answers, we will correctly compute the value
of v.]
See <a href="http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html">http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html</a></pre>
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