[llvm-branch-commits] [llvm] [LV] Bundle partial reductions inside VPExpressionRecipe (PR #147302)

[Sam Tebbs via llvm-branch-commits]

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@@ -2678,6 +2684,23 @@ InstructionCost VPExpressionRecipe::computeCost(ElementCount VF,
   case ExpressionTypes::ExtNegatedMulAccReduction:
   case ExpressionTypes::ExtMulAccReduction: {
     bool Negated = ExpressionType == ExpressionTypes::ExtNegatedMulAccReduction;
+    if (isa<VPPartialReductionRecipe>(ExpressionRecipes.back())) {
+      auto *Ext0R = cast<VPWidenCastRecipe>(ExpressionRecipes[0]);
+      auto *Ext1R = cast<VPWidenCastRecipe>(ExpressionRecipes[1]);
+      auto *Mul = cast<VPWidenRecipe>(ExpressionRecipes[2]);
+      unsigned Opcode =
+          ExpressionType == ExpressionTypes::ExtNegatedMulAccReduction
+              ? Instruction::Sub
+              : Instruction::Add;
+      return Ctx.TTI.getPartialReductionCost(
+          Opcode, Ctx.Types.inferScalarType(getOperand(0)),
+          Ctx.Types.inferScalarType(getOperand(1)), RedTy, VF,
+          TargetTransformInfo::getPartialReductionExtendKind(
+              Ext0R->getOpcode()),
+          TargetTransformInfo::getPartialReductionExtendKind(
+              Ext1R->getOpcode()),
+          Mul->getOpcode(), Ctx.CostKind);
+    }
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SamTebbs33 wrote:

They do share printing and matching code. There's no real difference (in terms of bundling) between a partial reduction bundle and a normal reduction bundle, except for costing. So I don't think it would be worth adding all the extra glue code just to have another expression type. We're moving towards making partial reductions VPReductionRecipes anyway.

https://github.com/llvm/llvm-project/pull/147302