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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 - Failure to simplify std::abs(a) * std::abs(a) -> a*a"
href="https://bugs.llvm.org/show_bug.cgi?id=39476">39476</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Failure to simplify std::abs(a) * std::abs(a) -> a*a
</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>Windows NT
</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>Common Code Generator Code
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>llvm-dev@redking.me.uk
</td>
</tr>
<tr>
<th>CC</th>
<td>filcab@gmail.com, llvm-bugs@lists.llvm.org, spatel+llvm@rotateright.com, tilkax@gmail.com
</td>
</tr></table>
<p>
<div>
<pre>#include <algorithm>
int bar_s32(int a)
{
return std::abs(a) * std::abs(a);
}
float bar_f32(float a)
{
return std::abs(a) * std::abs(a);
}
<a href="https://godbolt.org/z/4vIPwf">https://godbolt.org/z/4vIPwf</a>
clang manages this for fabs but not iabs:
_Z7bar_s32i: # @_Z7bar_s32i
movl %edi, %eax
negl %eax
cmovll %edi, %eax
imull %eax, %eax
retq
_Z7bar_f32f: # @_Z7bar_f32f
mulss %xmm0, %xmm0
retq
gcc:
_Z7bar_s32i:
imull %edi, %edi
movl %edi, %eax
ret
_Z7bar_f32f:
mulss %xmm0, %xmm0
ret</pre>
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