commit dd226803c220f02a5987f0ee9f9ac3ffe2b35c09
Author: Stefan Pintilie <stefanp@ca.ibm.com>
Date:   Fri May 28 11:17:46 2021 -0500

    Revert "[NFCI][LoopDeletion] Do not call complex analysis for known non-zero BTC"
    
    This reverts commit 7d418dadf6b1e6fd9bcccf7c5b5e1db74992ee70.

diff --git a/llvm/lib/Transforms/Scalar/LoopDeletion.cpp b/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
index da9a767d6fea..acc2056c4a54 100644
--- a/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopDeletion.cpp
@@ -314,8 +314,6 @@ breakBackedgeIfNotTaken(Loop *L, DominatorTree &DT, ScalarEvolution &SE,
     return LoopDeletionResult::Unmodified;
 
   auto *BTC = SE.getBackedgeTakenCount(L);
-  if (!isa<SCEVCouldNotCompute>(BTC) && SE.isKnownNonZero(BTC))
-    return LoopDeletionResult::Unmodified;
   if (!BTC->isZero() && !canProveExitOnFirstIteration(L, DT, SE, LI))
     return LoopDeletionResult::Unmodified;