[llvm] [VPlan] Introduce child regions as VPlan transform. (PR #129402)

[Florian Hahn via llvm-commits]

================
@@ -113,13 +88,6 @@ static bool isHeaderBB(BasicBlock *BB, Loop *L) {
   return L && BB == L->getHeader();
 }
 
-void PlainCFGBuilder::setRegionPredsFromBB(VPRegionBlock *Region,
-                                           BasicBlock *BB) {
-  // BB is a loop header block. Connect the region to the loop preheader.
-  Loop *LoopOfBB = LI->getLoopFor(BB);
-  Region->setPredecessors({getOrCreateVPBB(LoopOfBB->getLoopPredecessor())});
-}
-
 // Add operands to VPInstructions representing phi nodes from the input IR.
 void PlainCFGBuilder::fixHeaderPhis() {
   for (auto *Phi : PhisToFix) {
----------------
fhahn wrote:

I updated the patch to use the original order here and swap if needed when region is introduced.

https://github.com/llvm/llvm-project/pull/129402