[llvm] 4e74541 - [LoopUnroll] Fix not-rotated.ll by adding back a limitation was unintentionally

[Whitney Tsang via llvm-commits]

Author: Whitney Tsang
Date: 2020-05-29T03:05:58Z
New Revision: 4e74541a928090b3604094e239884b0ea0a631bb

URL: https://github.com/llvm/llvm-project/commit/4e74541a928090b3604094e239884b0ea0a631bb
DIFF: https://github.com/llvm/llvm-project/commit/4e74541a928090b3604094e239884b0ea0a631bb.diff

LOG: [LoopUnroll] Fix not-rotated.ll by adding back a limitation was unintentionally
removed in https://reviews.llvm.org/D80477

Added: 
    

Modified: 
    llvm/lib/Transforms/Utils/LoopUnroll.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
index 4525681855ce..06e9f7ff2f53 100644
--- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp
@@ -326,6 +326,11 @@ LoopUnrollResult llvm::UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI,
                          "branch in latch or a single exiting block.\n");
     return LoopUnrollResult::Unmodified;
   }
+  if (LatchBI->isConditional() && LatchBI != ExitingBI) {
+    LLVM_DEBUG(
+        dbgs() << "Can't unroll; a conditional latch must exit the loop");
+    return LoopUnrollResult::Unmodified;
+  }
   LLVM_DEBUG(dbgs() << "  Exiting Block = " << ExitingBI->getParent()->getName()
                     << "\n");