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

[Sam Tebbs via llvm-commits]

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@@ -2772,7 +2773,10 @@ class VPPartialReductionRecipe : public VPReductionRecipe {
         Opcode(Opcode), VFScaleFactor(ScaleFactor) {
     [[maybe_unused]] auto *AccumulatorRecipe =
         getChainOp()->getDefiningRecipe();
-    assert((isa<VPReductionPHIRecipe>(AccumulatorRecipe) ||
+    // When cloning as part of a VPExpressionRecipe the chain op could have
+    // replaced by a temporary VPValue, so it doesn't have a defining recipe.
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SamTebbs33 wrote:

Why do we need to assert that?

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