[llvm] [VPlan] Connect (MemRuntime|SCEV)Check blocks as VPlan transform (NFC). (PR #143879)

[Florian Hahn via llvm-commits]

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@@ -2022,61 +2004,35 @@ class GeneratedRTChecks {
   /// Adds the generated SCEVCheckBlock before \p LoopVectorPreHeader and
   /// adjusts the branches to branch to the vector preheader or \p Bypass,
   /// depending on the generated condition.
-  BasicBlock *emitSCEVChecks(BasicBlock *Bypass,
-                             BasicBlock *LoopVectorPreHeader) {
+  std::pair<Value *, BasicBlock *> emitSCEVChecks() {
     using namespace llvm::PatternMatch;
     if (!SCEVCheckCond || match(SCEVCheckCond, m_ZeroInt()))
-      return nullptr;
+      return {nullptr, nullptr};
 
-    auto *Pred = LoopVectorPreHeader->getSinglePredecessor();
-    BranchInst::Create(LoopVectorPreHeader, SCEVCheckBlock);
-
-    SCEVCheckBlock->getTerminator()->eraseFromParent();
-    SCEVCheckBlock->moveBefore(LoopVectorPreHeader);
-    Pred->getTerminator()->replaceSuccessorWith(LoopVectorPreHeader,
-                                                SCEVCheckBlock);
-
-    BranchInst &BI =
-        *BranchInst::Create(Bypass, LoopVectorPreHeader, SCEVCheckCond);
-    if (AddBranchWeights)
-      setBranchWeights(BI, SCEVCheckBypassWeights, /*IsExpected=*/false);
-    ReplaceInstWithInst(SCEVCheckBlock->getTerminator(), &BI);
-    // Mark the check as used, to prevent it from being removed during cleanup.
+    Value *Cond = SCEVCheckCond;
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fhahn wrote:

This is not really needed independent of the patch, simplified in 786ccb2c0e8c36ebe291d538f2e2784e52f9d94d

https://github.com/llvm/llvm-project/pull/143879