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

[via llvm-commits]

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@@ -2477,7 +2477,7 @@ static void introduceCheckBlockInVPlan(VPlan &Plan, BasicBlock *CheckIRBB) {
     assert(PreVectorPH->getNumSuccessors() == 2 && "Expected 2 successors");
     assert(PreVectorPH->getSuccessors()[0] == ScalarPH &&
            "Unexpected successor");
-    VPIRBasicBlock *CheckVPIRBB = VPIRBasicBlock::fromBasicBlock(CheckIRBB);
+    VPIRBasicBlock *CheckVPIRBB = Plan.createVPIRBasicBlock(CheckIRBB);
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ayalz wrote:

Such construction of VPBB's seems complementary of `VPBuilder`,  `VPlanHCFGBuilder`,  `VPRecipeBuilder`?

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