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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 - clang miscompiles at -O2 and above on valid code"
href="https://bugs.llvm.org/show_bug.cgi?id=38641">38641</a>
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<th>Summary</th>
<td>clang miscompiles at -O2 and above on valid code
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>LLVM Codegen
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>helloqirun@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>clang-r339936: first working build
clang-r339938: next failing build
$ clang-trunk -v
clang version 8.0.0 (trunk 340155)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
$ clang-trunk abc.c
$ ./a.out
$
$ clang-trunk -O2 abc.c
$ ./a.out
0
$ cat abc.c
int printf(const char *, ...);
int a = 1, b;
static short(c)(short d, int e) { return d < 0 ? d : d >> e; }
int main() {
char f = a;
if (c(f, 5))
printf("%d\n", b);
}</pre>
</div>
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