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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 - [AVX-512] Redundant instruction in Scatter sequence"
href="https://bugs.llvm.org/show_bug.cgi?id=34542">34542</a>
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<th>Summary</th>
<td>[AVX-512] Redundant instruction in Scatter sequence
</td>
</tr>
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<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>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<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>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>elena.demikhovsky@intel.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>This is the IR code, which stores the same i32 value in 16 random locations:
define void @foo(i32 %x, <16 x i32*> %addr) {
%y = insertelement <16 x i32>undef, i32 %x, i32 0
%y1 = shufflevector <16 x i32>%y, <16 x i32> undef, <16 x i32>zeroinitializer
br label %L
L:
call void @llvm.masked.scatter.v16i32.v16p0i32(<16 x i32> %y1, <16 x i32*>
%addr, i32 4, <16 x i1> <i1 true, i1 true, i1 true, i1 true, i1 true, i1 true,
i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1 true, i1
true, i1 true>)
ret void
}
declare void @llvm.masked.scatter.v16i32.v16p0i32(<16 x i32>, <16 x i32*>, i32,
<16 x i1>)
vpbroadcastd %edi, %zmm2
kxnorw %k0, %k0, %k1
kxnorw %k0, %k0, %k2
vpscatterqd %ymm2, (,%zmm0) {%k2}
vextracti64x4 $1, %zmm2, %ymm0 <== This instruction is redundant.
vpscatterqd %ymm0, (,%zmm1) {%k1}
I checked the similar sequence with Store - it is ok, the problem is only in
the Scatter.</pre>
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