[llvm] [SLP] Fix crash on trying to reshuffle a scalar that was vectorized. (PR #72295)

[Valery Dmitriev via llvm-commits]

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@@ -9164,7 +9164,8 @@ BoUpSLP::tryToGatherSingleRegisterExtractElements(
       continue;
     }
     auto *VecTy = dyn_cast<FixedVectorType>(EI->getVectorOperandType());
-    if (!VecTy || !isa<ConstantInt, UndefValue>(EI->getIndexOperand()))
+    if (!VecTy || !isa<ConstantInt, UndefValue>(EI->getIndexOperand()) ||
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valerydmit wrote:

Dependency is actually the other way around - a gather node operand depends on a vectorized node. But the dependency is not tracked anywhere so that we end up creating a shuffle of a value which was vectorized (and is in the deleted instructions list) , I do not like the idea to introduce yet another tracking mechanism. 


https://github.com/llvm/llvm-project/pull/72295