[llvm-bugs] [Bug 50261] New: [MCA] IsOptimizableRegisterMove bug with AVX XMM/YMM (but not SSE XMM!) eliminatible moves

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=50261

            Bug ID: 50261
           Summary: [MCA] IsOptimizableRegisterMove bug with AVX XMM/YMM
                    (but not SSE XMM!) eliminatible moves
           Product: tools
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: llvm-mca
          Assignee: unassignedbugs at nondot.org
          Reporter: lebedev.ri at gmail.com
                CC: andrea.dibiagio at gmail.com, llvm-bugs at lists.llvm.org,
                    matthew.davis at sony.com

https://github.com/llvm/llvm-project/commit/ee020b930d1299acf42b759dd15a44d2020ef963#diff-e74654f3176fcb70991259ed584e4ba815570d1ed991b1f65d91d3aebc3a6abbR220

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:
https://github.com/llvm/llvm-project/commit/9db4203883f57f34e7e88fd6deb761ef8a9f7d5a#diff-3be57f4b4cca33937ed8ee650ddb50eaae0464b0e021b709f6438cc8959152a3R220

Please note that the bug no longer reproduces after follow-up commit:
https://github.com/llvm/llvm-project/commit/758c173309edbd6ac3958eb08dc01b6524badff8#diff-e74654f3176fcb70991259ed584e4ba815570d1ed991b1f65d91d3aebc3a6abbR220

... 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..

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