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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 with "-newgvn" at -O2 on valid code"
href="https://bugs.llvm.org/show_bug.cgi?id=38619">38619</a>
</td>
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<tr>
<th>Summary</th>
<td>clang miscompiles with "-newgvn" at -O2 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>
<tr>
<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>It also affects clang-5.0 and clang-6.0.
clang-r312400: first working build
clang-r312401: next failing build
$ clang abc.c ; ./a.out
9
$ clang-4.0 -mllvm -enable-newgvn -O2 abc.c ; ./a.out
9
$ clang-5.0 -mllvm -enable-newgvn -O2 abc.c ; ./a.out
0
$ clang-trunk -mllvm -enable-newgvn -O2 abc.c ; ./a.out
0
$ clang-trunk -v
clang version 8.0.0 (trunk 340070)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
$ cat abc.c
void printf();
int a;
short b, c, d, f;
char e;
int g() {
d = 0;
for (;; ++d) {
b = f = d * a;
e = f % 0x95216DC9;
c |= e;
if (d)
return 3;
for (; a < 8; a = 9)
;
}
}
int main() {
g();
printf("%d\n", e);
}</pre>
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