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<body><span class="vcard"><a class="email" href="mailto:james.molloy@arm.com" title="James Molloy <james.molloy@arm.com>"> <span class="fn">James Molloy</span></a>
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<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Regression(281162): clang miscompiles some of chrome's tests"
href="https://llvm.org/bugs/show_bug.cgi?id=30373">bug 30373</a>
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<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 - Regression(281162): clang miscompiles some of chrome's tests"
href="https://llvm.org/bugs/show_bug.cgi?id=30373#c14">Comment # 14</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Regression(281162): clang miscompiles some of chrome's tests"
href="https://llvm.org/bugs/show_bug.cgi?id=30373">bug 30373</a>
from <span class="vcard"><a class="email" href="mailto:james.molloy@arm.com" title="James Molloy <james.molloy@arm.com>"> <span class="fn">James Molloy</span></a>
</span></b>
<pre>Hi Nico,
Thanks so much for taking so much effort to find a reduced testcase! As I
suspected, r281162 wasn't actually the problem commit, an earlier one was and
code permutation at r281162 exposed it.
The issue was that when picking a candidate for CSE, I was combining metadata
correctly but not AND-ing IR flags which in this testcase caused an "exact"
flag to erroneously propagate to a right shift when it wasn't there originally.
This is fixed in r281889.
I'm working on removing this whole slew of code in SimplifyCFG by creating a
new GVN-sinking pass - it causes far too much code churn and the number of
defects it's raised (in canonical form expectations, SROA, ...) is massive.
Thanks again,
James</pre>
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