diff options
Diffstat (limited to 'lib/Analysis/LoopAccessAnalysis.cpp')
| -rw-r--r-- | lib/Analysis/LoopAccessAnalysis.cpp | 52 |
1 files changed, 26 insertions, 26 deletions
diff --git a/lib/Analysis/LoopAccessAnalysis.cpp b/lib/Analysis/LoopAccessAnalysis.cpp index c6175bf9bee..a24d66011b8 100644 --- a/lib/Analysis/LoopAccessAnalysis.cpp +++ b/lib/Analysis/LoopAccessAnalysis.cpp @@ -176,8 +176,8 @@ const SCEV *llvm::replaceSymbolicStrideSCEV(PredicatedScalarEvolution &PSE, /// Calculate Start and End points of memory access. /// Let's assume A is the first access and B is a memory access on N-th loop -/// iteration. Then B is calculated as: -/// B = A + Step*N . +/// iteration. Then B is calculated as: +/// B = A + Step*N . /// Step value may be positive or negative. /// N is a calculated back-edge taken count: /// N = (TripCount > 0) ? RoundDown(TripCount -1 , VF) : 0 @@ -1317,7 +1317,7 @@ bool MemoryDepChecker::couldPreventStoreLoadForward(uint64_t Distance, return false; } -/// Given a non-constant (unknown) dependence-distance \p Dist between two +/// Given a non-constant (unknown) dependence-distance \p Dist between two /// memory accesses, that have the same stride whose absolute value is given /// in \p Stride, and that have the same type size \p TypeByteSize, /// in a loop whose takenCount is \p BackedgeTakenCount, check if it is @@ -1336,19 +1336,19 @@ static bool isSafeDependenceDistance(const DataLayout &DL, ScalarEvolution &SE, // If we can prove that // (**) |Dist| > BackedgeTakenCount * Step - // where Step is the absolute stride of the memory accesses in bytes, + // where Step is the absolute stride of the memory accesses in bytes, // then there is no dependence. // - // Ratioanle: - // We basically want to check if the absolute distance (|Dist/Step|) - // is >= the loop iteration count (or > BackedgeTakenCount). - // This is equivalent to the Strong SIV Test (Practical Dependence Testing, - // Section 4.2.1); Note, that for vectorization it is sufficient to prove + // Ratioanle: + // We basically want to check if the absolute distance (|Dist/Step|) + // is >= the loop iteration count (or > BackedgeTakenCount). + // This is equivalent to the Strong SIV Test (Practical Dependence Testing, + // Section 4.2.1); Note, that for vectorization it is sufficient to prove // that the dependence distance is >= VF; This is checked elsewhere. - // But in some cases we can prune unknown dependence distances early, and - // even before selecting the VF, and without a runtime test, by comparing - // the distance against the loop iteration count. Since the vectorized code - // will be executed only if LoopCount >= VF, proving distance >= LoopCount + // But in some cases we can prune unknown dependence distances early, and + // even before selecting the VF, and without a runtime test, by comparing + // the distance against the loop iteration count. Since the vectorized code + // will be executed only if LoopCount >= VF, proving distance >= LoopCount // also guarantees that distance >= VF. // const uint64_t ByteStride = Stride * TypeByteSize; @@ -1360,8 +1360,8 @@ static bool isSafeDependenceDistance(const DataLayout &DL, ScalarEvolution &SE, uint64_t DistTypeSize = DL.getTypeAllocSize(Dist.getType()); uint64_t ProductTypeSize = DL.getTypeAllocSize(Product->getType()); - // The dependence distance can be positive/negative, so we sign extend Dist; - // The multiplication of the absolute stride in bytes and the + // The dependence distance can be positive/negative, so we sign extend Dist; + // The multiplication of the absolute stride in bytes and the // backdgeTakenCount is non-negative, so we zero extend Product. if (DistTypeSize > ProductTypeSize) CastedProduct = SE.getZeroExtendExpr(Product, Dist.getType()); @@ -2212,24 +2212,24 @@ void LoopAccessInfo::collectStridedAccess(Value *MemAccess) { "versioning:"); LLVM_DEBUG(dbgs() << " Ptr: " << *Ptr << " Stride: " << *Stride << "\n"); - // Avoid adding the "Stride == 1" predicate when we know that + // Avoid adding the "Stride == 1" predicate when we know that // Stride >= Trip-Count. Such a predicate will effectively optimize a single // or zero iteration loop, as Trip-Count <= Stride == 1. - // + // // TODO: We are currently not making a very informed decision on when it is // beneficial to apply stride versioning. It might make more sense that the - // users of this analysis (such as the vectorizer) will trigger it, based on - // their specific cost considerations; For example, in cases where stride + // users of this analysis (such as the vectorizer) will trigger it, based on + // their specific cost considerations; For example, in cases where stride // versioning does not help resolving memory accesses/dependences, the - // vectorizer should evaluate the cost of the runtime test, and the benefit - // of various possible stride specializations, considering the alternatives - // of using gather/scatters (if available). - + // vectorizer should evaluate the cost of the runtime test, and the benefit + // of various possible stride specializations, considering the alternatives + // of using gather/scatters (if available). + const SCEV *StrideExpr = PSE->getSCEV(Stride); - const SCEV *BETakenCount = PSE->getBackedgeTakenCount(); + const SCEV *BETakenCount = PSE->getBackedgeTakenCount(); // Match the types so we can compare the stride and the BETakenCount. - // The Stride can be positive/negative, so we sign extend Stride; + // The Stride can be positive/negative, so we sign extend Stride; // The backdgeTakenCount is non-negative, so we zero extend BETakenCount. const DataLayout &DL = TheLoop->getHeader()->getModule()->getDataLayout(); uint64_t StrideTypeSize = DL.getTypeAllocSize(StrideExpr->getType()); @@ -2243,7 +2243,7 @@ void LoopAccessInfo::collectStridedAccess(Value *MemAccess) { CastedBECount = SE->getZeroExtendExpr(BETakenCount, StrideExpr->getType()); const SCEV *StrideMinusBETaken = SE->getMinusSCEV(CastedStride, CastedBECount); // Since TripCount == BackEdgeTakenCount + 1, checking: - // "Stride >= TripCount" is equivalent to checking: + // "Stride >= TripCount" is equivalent to checking: // Stride - BETakenCount > 0 if (SE->isKnownPositive(StrideMinusBETaken)) { LLVM_DEBUG( |