[llvm] AMDGPU: Add mir test for agpr constant reg_sequence handling (PR #129058)

[Stanislav Mekhanoshin via llvm-commits]

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@@ -781,6 +781,27 @@ bool SIFoldOperandsImpl::isUseSafeToFold(const MachineInstr &MI,
   return !TII->isSDWA(MI);
 }
 
+static MachineOperand *lookUpCopyChain(const SIInstrInfo &TII,
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rampitec wrote:

It does more than adding test. Needs restacking?

https://github.com/llvm/llvm-project/pull/129058