[llvm] [VPlan] Add initial CFG simplification, removing BranchOnCond true. (PR #106748)

[via llvm-commits]

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@@ -2817,6 +2817,7 @@ BasicBlock *InnerLoopVectorizer::createVectorizedLoopSkeleton(
   // faster.
   emitMemRuntimeChecks(LoopScalarPreHeader);
 
+  replaceVPBBWithIRVPBB(Plan.getScalarPreheader(), LoopScalarPreHeader);
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ayalz wrote:

> We could store the plan in all blocks w/o a parent region, there is already a field in all blocks to do so?

Agreed, it seems better to store the plan for orphan blocks in their existing field rather than null, at-least for unreachable blocks, although best maintain connectivity rather than have a block point to a plan which in turn cannot reach it?

https://github.com/llvm/llvm-project/pull/106748