[llvm] [VPlan] Hook IR blocks into VPlan during skeleton creation (NFC) (PR #114292)

[via llvm-commits]

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@@ -2511,13 +2531,14 @@ void InnerLoopVectorizer::emitIterationCountCheck(BasicBlock *Bypass) {
          "TC check is expected to dominate Bypass");
 
   // Update dominator for Bypass & LoopExit (if needed).
-  DT->changeImmediateDominator(Bypass, TCCheckBlock);
   BranchInst &BI =
       *BranchInst::Create(Bypass, LoopVectorPreHeader, CheckMinIters);
   if (hasBranchWeightMD(*OrigLoop->getLoopLatch()->getTerminator()))
     setBranchWeights(BI, MinItersBypassWeights, /*IsExpected=*/false);
   ReplaceInstWithInst(TCCheckBlock->getTerminator(), &BI);
   LoopBypassBlocks.push_back(TCCheckBlock);
+
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ayalz wrote:

Scalar preheader can be connected in VPlan from the outset, rather than here?

https://github.com/llvm/llvm-project/pull/114292