[llvm] [SystemZ] Fix Operand Retrieval for Vector Reduction Intrinsic in `shouldExpandReduction` (PR #88874)

[Jonas Paulsson via llvm-commits]

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@@ -1322,26 +1323,30 @@ SystemZTTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
   return BaseT::getIntrinsicInstrCost(ICA, CostKind);
 }
 
+// Find the type of the vector operand indicated by index.
+// Asserts that the operand indicated is actually a vector.
+FixedVectorType *getOperandVectorType(const IntrinsicInst *II, unsigned Index) {
+  auto *T = II->getOperand(Index)->getType();
+  assert(T->isVectorTy());
+  return cast<FixedVectorType>(T);
+}
+
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JonPsson1 wrote:

It's kind of interesting if it is needed or not, and maybe also a matter of style, perhaps. @uweigand maybe has an opinion as well?

https://github.com/llvm/llvm-project/pull/88874