[llvm] [TwoAddressInstruction] Use isPlainlyKilled in processTiedPairs (PR #65976)

[Simon Pilgrim via llvm-commits]

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@@ -477,3 +451,6 @@ declare i5 @llvm.fshl.i5(i5, i5, i5)
 
 declare <4 x i32> @llvm.fshl.v4i32(<4 x i32>, <4 x i32>, <4 x i32>)
 declare <4 x i32> @llvm.fshr.v4i32(<4 x i32>, <4 x i32>, <4 x i32>)
+;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
+; SSE2-LIS: {{.*}}
+; SSE2-LV: {{.*}}
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RKSimon wrote:

Remove these prefixes from the RUN lines?

https://github.com/llvm/llvm-project/pull/65976