[llvm] [VPlan] Manage created blocks directly in VPlan. (NFC) (PR #120918)

[via llvm-commits]

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@@ -960,15 +953,13 @@ void VPlan::prepareToExecute(Value *TripCountV, Value *VectorTripCountV,
 /// have a single predecessor, which is rewired to the new VPIRBasicBlock. All
 /// successors of VPBB, if any, are rewired to the new VPIRBasicBlock.
 static void replaceVPBBWithIRVPBB(VPBasicBlock *VPBB, BasicBlock *IRBB) {
-  VPIRBasicBlock *IRVPBB = VPIRBasicBlock::fromBasicBlock(IRBB);
+  VPIRBasicBlock *IRVPBB = VPBB->getPlan()->createVPIRBasicBlock(IRBB);
   for (auto &R : make_early_inc_range(*VPBB)) {
     assert(!R.isPhi() && "Tried to move phi recipe to end of block");
     R.moveBefore(*IRVPBB, IRVPBB->end());
   }
 
   VPBlockUtils::reassociateBlocks(VPBB, IRVPBB);
----------------
ayalz wrote:

```suggestion
  VPBlockUtils::reassociateBlocks(VPBB, IRVPBB);
  // VPBB is now dead and will be cleaned up when the plan gets destroyed.
```

https://github.com/llvm/llvm-project/pull/120918