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<body><span class="vcard"><a class="email" href="mailto:evstupac@gmail.com" title="Evgeny Stupachenko <evstupac@gmail.com>"> <span class="fn">Evgeny Stupachenko</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - wrong code bug"
href="https://llvm.org/bugs/show_bug.cgi?id=27392">bug 27392</a>
<br>
<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
</td>
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<tr>
<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>FIXED
</td>
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - wrong code bug"
href="https://llvm.org/bugs/show_bug.cgi?id=27392#c5">Comment # 5</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - wrong code bug"
href="https://llvm.org/bugs/show_bug.cgi?id=27392">bug 27392</a>
from <span class="vcard"><a class="email" href="mailto:evstupac@gmail.com" title="Evgeny Stupachenko <evstupac@gmail.com>"> <span class="fn">Evgeny Stupachenko</span></a>
</span></b>
<pre>evstupac committed rL267662: The patch fixes PR27392..
The patch fixes PR27392.
Summary:
It is incorrect to compare TripCount (which is BECount + 1)
with extraiters (or Count) to check if we should enter unrolled
loop or not, because TripCount can potentially overflow
(when BECount is max unsigned integer).
While comparing BECount with (Count - 1) is overflow safe and
therefore correct.
Reviewer: hfinkel
Differential Revision: <a href="http://reviews.llvm.org/D19256">http://reviews.llvm.org/D19256</a>
From: Evgeny Stupachenko <<a href="mailto:evstupac@gmail.com">evstupac@gmail.com</a>>
Files:
/llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
/llvm/trunk/test/Transforms/LoopUnroll/AArch64/runtime-loop.ll
/llvm/trunk/test/Transforms/LoopUnroll/runtime-loop.ll
/llvm/trunk/test/Transforms/LoopUnroll/runtime-loop1.ll
/llvm/trunk/test/Transforms/LoopUnroll/tripcount-overflow.ll
Users:
evstupac (Author)
<a href="http://reviews.llvm.org/rL267662">http://reviews.llvm.org/rL267662</a></pre>
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