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-rw-r--r--llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp10
1 files changed, 10 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index c3761dcf4e8..fa6214f89f0 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -639,6 +639,16 @@ static bool tryToUnrollLoop(Loop *L, DominatorTree &DT, LoopInfo *LI,
Count = (std::max(UP.PartialThreshold, 3u) - 2) / (LoopSize - 2);
while (Count != 0 && TripCount % Count != 0)
Count--;
+ if (Count <= 1) {
+ // If there is no Count that is modulo of TripCount, set Count to
+ // largest power-of-two factor that satisfies the threshold limit.
+ Count = (std::max(UP.PartialThreshold, 3u) - 2) / (LoopSize - 2);
+ UnrolledSize = (LoopSize - 2) * Count + 2;
+ while (Count != 0 && UnrolledSize > UP.PartialThreshold) {
+ Count >>= 1;
+ UnrolledSize = (LoopSize - 2) * Count + 2;
+ }
+ }
}
} else if (Unrolling == Runtime) {
if (!AllowRuntime && !CountSetExplicitly) {
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