[llvm] [SLP] Compute a shuffle mask for getGatherCost (PR #85330)

[Alexey Bataev via llvm-commits]

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@@ -10516,6 +10516,7 @@ InstructionCost BoUpSLP::getGatherCost(ArrayRef<Value *> VL,
           TTI->getVectorInstrCost(Instruction::InsertElement, VecTy, CostKind,
                                   I, Constant::getNullValue(VecTy), V);
   };
+  SmallVector<int> ShuffleMask(VL.size(), -1);
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alexey-bataev wrote:

```suggestion
  SmallVector<int> ShuffleMask(VL.size(), PoisonMaskElem);
```

https://github.com/llvm/llvm-project/pull/85330