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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Thread safety analysis: False negatives for exclusive/shared joins on back edges"
href="https://bugs.llvm.org/show_bug.cgi?id=51913">51913</a>
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<th>Summary</th>
<td>Thread safety analysis: False negatives for exclusive/shared joins on back edges
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>trunk
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<th>Hardware</th>
<td>All
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Frontend
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>aaronpuchert@alice-dsl.net
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>Since <a href="https://reviews.llvm.org/D102026">https://reviews.llvm.org/D102026</a> we don't warn on this code:
// <a href="https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h">https://clang.llvm.org/docs/ThreadSafetyAnalysis.html#mutex-h</a>
#include "mutex.h"
Mutex mu;
int x GUARDED_BY(mu);
void f() {
MutexLocker scope(&mu);
for (unsigned i = 1; i < 10; ++i) {
x = 1;
if (i == 5) {
scope.Unlock();
scope.ReaderLock();
}
}
}
On the first iteration we have mu exclusively and can modify x, but on later
iterations we might not. So we can't allow this join to be silent.</pre>
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