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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 - Failed to combine -smax(-x,-y) to smin(x,y)"
href="https://bugs.llvm.org/show_bug.cgi?id=43310">43310</a>
</td>
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<th>Summary</th>
<td>Failed to combine -smax(-x,-y) to smin(x,y)
</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>Scalar Optimizations
</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>lebedev.ri@gmail.com, llvm-bugs@lists.llvm.org, spatel+llvm@rotateright.com
</td>
</tr></table>
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<div>
<pre>Noticed while investigating [<a class="bz_bug_link
bz_status_CONFIRMED "
title="CONFIRMED - [DAGCombine] Convert isNegatibleForFree/GetNegatedExpression to a target hook"
href="show_bug.cgi?id=42863">Bug #42863</a>] - its a rare case where we do better
on float than integer!
Current codegen: <a href="https://gcc.godbolt.org/z/epgWrG">https://gcc.godbolt.org/z/epgWrG</a>
auto min_f32(float x, float y) {
return std::min(x, y);
}
auto neg_max_f32(float x, float y) {
return -std::max(-x, -y);
}
auto min_s32(int x, int y) {
return std::min(x, y);
}
auto neg_max_s32(int x, int y) {
return -std::max(-x, -y);
}
min_f32(float, float):
vminss %xmm0, %xmm1, %xmm0
retq
neg_max_f32(float, float):
vminss %xmm0, %xmm1, %xmm0
retq
min_s32(int, int):
movl %edi, %eax
cmpl %edi, %esi
cmovlel %esi, %eax
retq
neg_max_s32(int, int):
movl %esi, %eax
negl %edi
negl %eax
cmpl %eax, %edi
cmovgel %edi, %eax
negl %eax
retq
vs gcc:
min_f32(float, float):
vminss %xmm0, %xmm1, %xmm0
ret
neg_max_f32(float, float):
vminss %xmm0, %xmm1, %xmm0
ret
min_s32(int, int):
cmpl %edi, %esi
movl %edi, %eax
cmovle %esi, %eax
ret
neg_max_s32(int, int):
cmpl %esi, %edi
movl %esi, %eax
cmovle %edi, %eax
ret</pre>
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