[llvm] [LoopVectorizer] Add support for partial reductions (PR #92418)

[Florian Hahn via llvm-commits]

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@@ -291,6 +291,53 @@ InstructionCost VPRecipeBase::computeCost(ElementCount VF,
   llvm_unreachable("subclasses should implement computeCost");
 }
 
+InstructionCost
+VPPartialReductionRecipe::computeCost(ElementCount VF,
+                                      VPCostContext &Ctx) const {
+  auto *BinOp = cast<BinaryOperator>(getOperand(0)->getUnderlyingValue());
+  auto *PhiR = cast<VPReductionPHIRecipe>(getOperand(1)->getDefiningRecipe());
+  auto *Phi = cast<PHINode>(PhiR->getUnderlyingValue());
+  auto *ExtA = cast<Instruction>(BinOp->getOperand(0));
+  auto *ExtB = cast<Instruction>(BinOp->getOperand(1));
+  Value *A = ExtA->getOperand(0);
+  return Ctx.TTI.getPartialReductionCost(
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fhahn wrote:

Still pending?

https://github.com/llvm/llvm-project/pull/92418