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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Regressed popcnt of unsigned short"
href="https://bugs.llvm.org/show_bug.cgi?id=52056">52056</a>
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<th>Summary</th>
<td>Regressed popcnt of unsigned short
</td>
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<tr>
<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: X86
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>david.bolvansky@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, pengfei.wang@intel.com, spatel+llvm@rotateright.com
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<p>
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<pre>int pc(unsigned short a) { return __builtin_popcount(a); }
LLVM trunk
pc(unsigned short): # @pc(unsigned short)
popcntw %di, %ax
movzwl %ax, %eax
retq
LLVM 12:
pc(unsigned short): # @pc(unsigned short)
popcntl %edi, %eax
retq
pc(unsigned short): # @pc(unsigned short)
popcntl %edi, %eax
retq
Maybe the solution is to add i16 -> i32 handling here in X86ISelLowering ?
if (Subtarget.hasPOPCNT()) {
setOperationPromotedToType(ISD::CTPOP, MVT::i8, MVT::i32);
} else { ....
<a href="https://gcc.godbolt.org/z/P7Pc63j1K">https://gcc.godbolt.org/z/P7Pc63j1K</a></pre>
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