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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Loop flattening not performed?"
href="https://bugs.llvm.org/show_bug.cgi?id=40581">40581</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Loop flattening not performed?
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</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>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>lebedev.ri@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre><a href="https://godbolt.org/z/B3VM2A">https://godbolt.org/z/B3VM2A</a>
void v0(int n, int *A, int *B) {
int k = 0;
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++) {
A[k] = B[k];
k++;
}
}
is equivalent to
void v1(int n, int *A, int *B) {
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++) {
int k = i*n+j;
A[k] = B[k];
k++;
}
}
(Also, which one of these ^ is better? clang does not optimize them into the
same IR)
Shouldn't that be transformed into
void v2(int n, int *A, int *B) {
for(int k = 0; k < n * n; k++)
A[k] = B[k];
}
?</pre>
</div>
</p>
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