[llvm] [LoopPeel] Fix BFI when peeling last iteration without guard (PR #168250)

[Joel E. Denny via llvm-commits]

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@@ -1183,8 +1183,33 @@ bool llvm::peelLoop(Loop *L, unsigned PeelCount, bool PeelLast, LoopInfo *LI,
 
     // If the original loop may only execute a single iteration we need to
     // insert a trip count check and skip the original loop with the last
-    // iteration peeled off if necessary.
-    if (!SE->isKnownNonZero(BTC)) {
+    // iteration peeled off if necessary.  Either way, we must update branch
+    // weights to maintain the loop body frequency.
+    if (SE->isKnownNonZero(BTC)) {
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jdenny-ornl wrote:

AFK today. But that is already included.

https://github.com/llvm/llvm-project/pull/168250