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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 --- - AVX512: FastISel generates invalid seto"
href="https://llvm.org/bugs/show_bug.cgi?id=30981">30981</a>
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<th>Summary</th>
<td>AVX512: FastISel generates invalid seto
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: X86
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>mkuper@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>craig.topper@gmail.com, igor.breger@intel.com, llvm-bugs@lists.llvm.org, zvi.rackover@intel.com
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>For this IR:
define i64 @foo(i64 %arg) {
bb:
%tmp1 = tail call { i64, i1 } @llvm.umul.with.overflow.i64(i64 %arg, i64 4)
%tmp2 = extractvalue { i64, i1 } %tmp1, 1
%tmp3 = select i1 %tmp2, i64 -1, i64 %arg
ret i64 %tmp3
}
; Function Attrs: nounwind readnone
declare { i64, i1 } @llvm.umul.with.overflow.i64(i64, i64)
Compiling for AVX512 with -O0 we get:
$ bin/llc ~/llvm/temp/badnew.ll -O0 -o - -mattr=+avx512f
[...]
movq %rdi, %rax
mulq %rdx
seto %k0
[...]
seto %k0 looks like a nonsense instruction, and ends up getting encoded as seto
%al.</pre>
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</p>
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