[llvm] [LoopBoundSplit] Fix edge connections during transformation (PR #192106)

[Congzhe Cao via llvm-commits]

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@@ -356,6 +356,11 @@ static bool splitLoopBound(Loop &L, DominatorTree &DT, LoopInfo &LI,
   BasicBlock *PostLoopPreHeader = PostLoop->getLoopPreheader();
   IRBuilder<> Builder(&PostLoopPreHeader->front());
 
+  // Replace exit branch target of pre-loop by post-loop's preheader.
+  if (L.getExitBlock() == ExitingCond.BI->getSuccessor(0))
+    ExitingCond.BI->setSuccessor(0, PostLoopPreHeader);
+  else
+    ExitingCond.BI->setSuccessor(1, PostLoopPreHeader);
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CongzheUalberta wrote:

Thanks, I can add a comment that says something like below:

"Inside LoopInfoBase::verify() it computes another fresh LoopInfo (`OtherLI`) and compare it with the current `LI` for verification. Update the branch here to keep the IR valid in order to correctly compute `OtherLI`, otherwise `OtherLI` would be incorrect which fails the comparison with the current `LI`"

https://github.com/llvm/llvm-project/pull/192106