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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - REGRESSION(184445): Need to insert a StoreBarrier when we don't know child's epoch"
href="https://bugs.webkit.org/show_bug.cgi?id=159537">159537</a>
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<th>Summary</th>
<td>REGRESSION(184445): Need to insert a StoreBarrier when we don't know child's epoch
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<th>Classification</th>
<td>Unclassified
</td>
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<th>Product</th>
<td>WebKit
</td>
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<th>Version</th>
<td>WebKit Nightly Build
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<th>Hardware</th>
<td>Unspecified
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<th>OS</th>
<td>Unspecified
</td>
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>Major
</td>
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<th>Priority</th>
<td>P2
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<th>Component</th>
<td>JavaScriptCore
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<th>Assignee</th>
<td>webkit-unassigned@lists.webkit.org
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<th>Reporter</th>
<td>msaboff@apple.com
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<pre>In StoreBarrierInsertionPhase::considerBarrier(Edge base, Edge child), there is the following comment and code:
// Something we watch out for here is that the null epoch is a catch-all for objects
// allocated before we did any epoch tracking. Two objects being in the null epoch
// means that we don't know their epoch relationship.
if (!!base->epoch() && base->epoch() >= child->epoch()) {
if (verbose)
dataLog(" Rejecting because of epoch ordering.\n");
return;
}
The test doesn't check that the child's epoch is null and therefore we won't insert a barrier for the case where we allocate the base object, but don't know when the child object was allocated.
<rdar://problem/23438751></pre>
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