[llvm] [LoopVectorizer] Add support for chaining partial reductions (PR #120272)

[Sam Tebbs via llvm-commits]

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@@ -2453,7 +2453,9 @@ class VPPartialReductionRecipe : public VPSingleDefRecipe {
       : VPSingleDefRecipe(VPDef::VPPartialReductionSC,
                           ArrayRef<VPValue *>({Op0, Op1}), ReductionInst),
         Opcode(Opcode) {
-    assert(isa<VPReductionPHIRecipe>(getOperand(1)->getDefiningRecipe()) &&
+    auto *DefiningRecipe = getOperand(1)->getDefiningRecipe();
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SamTebbs33 wrote:

Perhaps `AccumulatorRecipe` would be more descriptive.

https://github.com/llvm/llvm-project/pull/120272