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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 - [LoopInterchange] Loops should not interchanged due to dependencies"
href="https://bugs.llvm.org/show_bug.cgi?id=47915">47915</a>
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<tr>
<th>Summary</th>
<td>[LoopInterchange] Loops should not interchanged due to dependencies
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>All
</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>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Loop Optimizer
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>chengeng5@huawei.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>$ clang -mllvm -enable-loopinterchange -O2 reproducer.c -w && ./a.out
4096
0
4096
0
$ clang -O0 reproducer.c -w && ./a.out
4096
4096
4096
4096
reproducer.c:
#include <stdio.h>
int a;
int c[4][4];
*f = &a;
void test_deps() {
for (int i = 0; i <= 3; i++) {
for (int j = 0; j <= 3; j++) {
*f ^= 0x1000;
c[j][i] = *f;
}
}
}
main() {
test_deps();
for (int k = 0; k < 4; k++)
printf("%d\n", c[0][k]);
}</pre>
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