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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - missing cse for smin/smax"
href="https://llvm.org/bugs/show_bug.cgi?id=24441">24441</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>missing cse for smin/smax
</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>wmi@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>For testcase 1.c:
int m, n;
void foo(int x, int y) {
m = (x < y) ? x : y;
n = (y < x) ? y : x;
}
~/workarea/llvm-r243652/build/bin/clang -O2 -S 1.c
foo: # @foo
.cfi_startproc
# BB#0: # %entry
cmpl %esi, %edi
movl %esi, %eax
cmovlel %edi, %eax
movl %eax, m(%rip)
cmpl %edi, %esi
cmovlel %esi, %edi
movl %edi, n(%rip)
retq
.Lfunc_end0:
.size foo, .Lfunc_end0-foo
.cfi_endproc
llvm failed to find out both of the exprs to compute m and n were smin(x, y).
Fixing this is important to cleanup redundency introduced by expansion of SCEV
because building and then expanding SCEV often transformed one form of
smin/smax to another.</pre>
</div>
</p>
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