[llvm] [VPlan] Model middle block via VPIRBasicBlock. (PR #95816)

[via llvm-commits]

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@@ -469,29 +485,13 @@ void VPBasicBlock::execute(VPTransformState *State) {
   };
 
   // 1. Create an IR basic block, or reuse the last one or ExitBB if possible.
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ayalz wrote:

Drop "or ExitBB"?

https://github.com/llvm/llvm-project/pull/95816