[llvm] [LV] Add initial support for vectorizing literal struct return values (PR #109833)

[Benjamin Maxwell via llvm-commits]

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@@ -1506,6 +1514,8 @@ InstructionCost VPWidenRecipe::computeCost(ElementCount VF,
     return Ctx.TTI.getArithmeticInstrCost(Instruction::Mul, VectorTy,
                                           Ctx.CostKind);
   }
+  case Instruction::ExtractValue:
+    return 0;
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MacDue wrote:

I don't think so, I did look around (including `getVectorInstrCost()`), but it does not look like there's a hook for this right now. `getVectorInstrCost()` is currently only for `insertelement` and `extractelement`. I guess I could modify this hook to handle it, or add a new one though? 

https://github.com/llvm/llvm-project/blob/455b3d6df20c9bb50cdba66fd2f3202bc43eb4ac/llvm/lib/Analysis/TargetTransformInfo.cpp#L1079-L1084

https://github.com/llvm/llvm-project/pull/109833