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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [MCA] IsOptimizableRegisterMove bug with AVX XMM/YMM (but not SSE XMM!) eliminatible moves"
href="https://bugs.llvm.org/show_bug.cgi?id=50261">50261</a>
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<th>Summary</th>
<td>[MCA] IsOptimizableRegisterMove bug with AVX XMM/YMM (but not SSE XMM!) eliminatible moves
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<th>Product</th>
<td>tools
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>llvm-mca
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>lebedev.ri@gmail.com
</td>
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<th>CC</th>
<td>andrea.dibiagio@gmail.com, llvm-bugs@lists.llvm.org, matthew.davis@sony.com
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<pre><a href="https://github.com/llvm/llvm-project/commit/ee020b930d1299acf42b759dd15a44d2020ef963#diff-e74654f3176fcb70991259ed584e4ba815570d1ed991b1f65d91d3aebc3a6abbR220">https://github.com/llvm/llvm-project/commit/ee020b930d1299acf42b759dd15a44d2020ef963#diff-e74654f3176fcb70991259ed584e4ba815570d1ed991b1f65d91d3aebc3a6abbR220</a>
I.e. given the snippet
# LLVM-MCA-BEGIN
vmovaps %xmm0, %xmm1
vmovaps %xmm1, %xmm2
vmovaps %xmm2, %xmm3
vmovaps %xmm3, %xmm4
vmovaps %xmm4, %xmm5
vmovaps %xmm5, %xmm6
vmovaps %xmm6, %xmm7
vmovaps %xmm7, %xmm8
vmovaps %xmm8, %xmm9
vmovaps %xmm9, %xmm10
vmovaps %xmm10, %xmm11
vmovaps %xmm11, %xmm12
vmovaps %xmm12, %xmm13
vmovaps %xmm13, %xmm14
vmovaps %xmm14, %xmm15
vmovaps %xmm15, %xmm0
# LLVM-MCA-END
and commit 9db4203883f57f34e7e88fd6deb761ef8a9f7d5a,
somehow MCA says that the last move actually executes.
The same issue is observable for YMM moves,
but not SSE XMM moves:
<a href="https://github.com/llvm/llvm-project/commit/9db4203883f57f34e7e88fd6deb761ef8a9f7d5a#diff-3be57f4b4cca33937ed8ee650ddb50eaae0464b0e021b709f6438cc8959152a3R220">https://github.com/llvm/llvm-project/commit/9db4203883f57f34e7e88fd6deb761ef8a9f7d5a#diff-3be57f4b4cca33937ed8ee650ddb50eaae0464b0e021b709f6438cc8959152a3R220</a>
Please note that the bug no longer reproduces after follow-up commit:
<a href="https://github.com/llvm/llvm-project/commit/758c173309edbd6ac3958eb08dc01b6524badff8#diff-e74654f3176fcb70991259ed584e4ba815570d1ed991b1f65d91d3aebc3a6abbR220">https://github.com/llvm/llvm-project/commit/758c173309edbd6ac3958eb08dc01b6524badff8#diff-e74654f3176fcb70991259ed584e4ba815570d1ed991b1f65d91d3aebc3a6abbR220</a>
... so you'll need to develop the fix against non-HEAD,
and i don't know if you will be able to add a test..</pre>
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