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

[Graham Hunter via llvm-commits]

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@@ -233,6 +233,11 @@ Type *VPTypeAnalysis::inferScalarTypeForRecipe(const VPReplicateRecipe *R) {
   llvm_unreachable("Unhandled opcode");
 }
 
+Type *
+VPTypeAnalysis::inferScalarTypeForRecipe(const VPPartialReductionRecipe *R) {
+  return R->getUnderlyingInstr()->getType();
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huntergr-arm wrote:

I think it would just be moving `VPPartialReductionRecipe` into the `.Case` statement above the current one (alongside `VPReductionRecipe`) in the base `inferScalarType(const VPValue *)`, which will recursively infer the scalar type based on the first operand. Then you wouldn't need this extra method.

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