diff options
Diffstat (limited to 'llvm/lib/Transforms/Vectorize')
| -rw-r--r-- | llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp index f5ec20fda85..973617cc0c7 100644 --- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp +++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp @@ -208,7 +208,7 @@ static cl::opt<unsigned> SmallLoopCost( "The cost of a loop that is considered 'small' by the interleaver.")); static cl::opt<bool> LoopVectorizeWithBlockFrequency( - "loop-vectorize-with-block-frequency", cl::init(false), cl::Hidden, + "loop-vectorize-with-block-frequency", cl::init(true), cl::Hidden, cl::desc("Enable the use of the block frequency analysis to access PGO " "heuristics minimizing code growth in cold regions and being more " "aggressive in hot regions.")); @@ -8347,9 +8347,21 @@ bool LoopVectorizePass::processLoop(Loop *L) { // Check the loop for a trip count threshold: vectorize loops with a tiny trip // count by optimizing for size, to minimize overheads. - unsigned ExpectedTC = SE->getSmallConstantMaxTripCount(L); - bool HasExpectedTC = (ExpectedTC > 0); - + // Prefer constant trip counts over profile data, over upper bound estimate. + unsigned ExpectedTC = 0; + bool HasExpectedTC = false; + if (const SCEVConstant *ConstExits = + dyn_cast<SCEVConstant>(SE->getBackedgeTakenCount(L))) { + const APInt &ExitsCount = ConstExits->getAPInt(); + // We are interested in small values for ExpectedTC. Skip over those that + // can't fit an unsigned. + if (ExitsCount.ult(std::numeric_limits<unsigned>::max())) { + ExpectedTC = static_cast<unsigned>(ExitsCount.getZExtValue()) + 1; + HasExpectedTC = true; + } + } + // ExpectedTC may be large because it's bound by a variable. Check + // profiling information to validate we should vectorize. if (!HasExpectedTC && LoopVectorizeWithBlockFrequency) { auto EstimatedTC = getLoopEstimatedTripCount(L); if (EstimatedTC) { @@ -8357,6 +8369,10 @@ bool LoopVectorizePass::processLoop(Loop *L) { HasExpectedTC = true; } } + if (!HasExpectedTC) { + ExpectedTC = SE->getSmallConstantMaxTripCount(L); + HasExpectedTC = (ExpectedTC > 0); + } if (HasExpectedTC && ExpectedTC < TinyTripCountVectorThreshold) { DEBUG(dbgs() << "LV: Found a loop with a very small trip count. " |
