[llvm] [SLP] Fix crash on extractelement with out-of-bounds index.....Fixes … (PR #176918)

[Alexey Bataev via llvm-commits]

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@@ -15042,7 +15042,14 @@ BoUpSLP::getEntryCost(const TreeEntry *E, ArrayRef<Value *> VectorizedVals,
       }
       if (DemandedElts.isZero())
         DemandedElts = APInt::getZero(getNumElements(SrcVecTy));
-      DemandedElts.setBit(*getExtractIndex(I));
+      unsigned ExtIdx = *getExtractIndex(I);
+      //Out-of-bounds extractelement produces poison.So it do no corresponds to a concrete vector lane,
+      // so instead of treating it as an invalid pattern we can avoid marking any demanded element
+      if (ExtIdx  < DemandedElts.getBitWidth())
+      {
+        DemandedElts.setBit(ExtIdx);
+      }
+      // DemandedElts.setBit(*getExtractIndex(I));
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alexey-bataev wrote:

I don't see the changes in getExtractIndex

https://github.com/llvm/llvm-project/pull/176918