[llvm] [AMDGPU] Reject src1 immediates with dpp when unsupported (PR #201494)

[Matt Arsenault via llvm-commits]

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@@ -5543,6 +5549,10 @@ bool SIInstrInfo::verifyInstruction(const MachineInstr &MI,
       ErrInfo = "DPP src1 cannot be SGPR on this subtarget";
       return false;
     }
+    if (Src1MO.isImm()) {
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arsenm wrote:

Missing verifier test 

https://github.com/llvm/llvm-project/pull/201494