[llvm] [SimplifyCFG][SCCP] Preserve loop metadata when replacing terminators with branches (PR #220144)

[Byeongjee Kang via llvm-commits]

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@@ -273,7 +268,11 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions,
     // now.
     if (TheOnlyDest) {
       // Insert the new branch.
-      Builder.CreateBr(TheOnlyDest);
+      UncondBrInst *NewBI = Builder.CreateBr(TheOnlyDest, SI);
+      // Preserve loop metadata when every switch destination is retained.
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byeongjee wrote:

This is conservative, but going further would require extra loop analysis.

https://github.com/llvm/llvm-project/pull/220144