[llvm] [VPlan] Use ResumePhi to create reduction resume phis. (PR #110004)

[via llvm-commits]

================
@@ -7493,40 +7501,15 @@ static void createAndCollectMergePhiForReduction(
          "when vectorizing the epilogue loop, we need a resume phi from main "
          "vector loop");
 
-  // TODO: bc.merge.rdx should not be created here, instead it should be
-  // modeled in VPlan.
   BasicBlock *LoopScalarPreHeader = OrigLoop->getLoopPreheader();
-  // Create a phi node that merges control-flow from the backedge-taken check
-  // block and the middle block.
----------------
ayalz wrote:

nit: what is "backedge-taken check block", abbreviated in "BCBlock"?

https://github.com/llvm/llvm-project/pull/110004