diff options
Diffstat (limited to 'llvm/lib/Transforms/Utils/LoopUnroll.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Utils/LoopUnroll.cpp | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/llvm/lib/Transforms/Utils/LoopUnroll.cpp b/llvm/lib/Transforms/Utils/LoopUnroll.cpp index 3fdcd0d..5f7395d 100644 --- a/llvm/lib/Transforms/Utils/LoopUnroll.cpp +++ b/llvm/lib/Transforms/Utils/LoopUnroll.cpp @@ -256,8 +256,7 @@ void llvm::simplifyLoopAfterUnroll(Loop *L, bool SimplifyIVs, LoopInfo *LI, /// /// PreserveCondBr indicates whether the conditional branch of the LatchBlock /// needs to be preserved. It is needed when we use trip count upper bound to -/// fully unroll the loop. If PreserveOnlyFirst is also set then only the first -/// conditional branch needs to be preserved. +/// fully unroll the loop. /// /// Similarly, TripMultiple divides the number of times that the LatchBlock may /// execute without exiting the loop. @@ -381,6 +380,11 @@ LoopUnrollResult llvm::UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI, any_of(ExitBlocks, [](const BasicBlock *BB) { return isa<PHINode>(BB->begin()); }); + const unsigned MaxTripCount = SE->getSmallConstantMaxTripCount(L); + const bool MaxOrZero = SE->isBackedgeTakenCountMaxOrZero(L); + + const bool PreserveOnlyFirst = ULO.Count == MaxTripCount && MaxOrZero; + // The current loop unroll pass can unroll loops that have // (1) single latch; and // (2a) latch is unconditional; or @@ -755,7 +759,7 @@ LoopUnrollResult llvm::UnrollLoop(Loop *L, UnrollLoopOptions ULO, LoopInfo *LI, auto WillExit = [&](unsigned i, unsigned j) -> Optional<bool> { if (CompletelyUnroll) { - if (ULO.PreserveCondBr && j && !(ULO.PreserveOnlyFirst && i != 0)) + if (ULO.PreserveCondBr && j && !(PreserveOnlyFirst && i != 0)) return None; return j == 0; } |