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Diffstat (limited to 'llvm/lib/Analysis/VectorUtils.cpp')
| -rw-r--r-- | llvm/lib/Analysis/VectorUtils.cpp | 1161 |
1 files changed, 1161 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/VectorUtils.cpp b/llvm/lib/Analysis/VectorUtils.cpp new file mode 100644 index 000000000000..600f57ab9d71 --- /dev/null +++ b/llvm/lib/Analysis/VectorUtils.cpp @@ -0,0 +1,1161 @@ +//===----------- VectorUtils.cpp - Vectorizer utility functions -----------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file defines vectorizer utilities. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Analysis/VectorUtils.h" +#include "llvm/ADT/EquivalenceClasses.h" +#include "llvm/Analysis/DemandedBits.h" +#include "llvm/Analysis/LoopInfo.h" +#include "llvm/Analysis/LoopIterator.h" +#include "llvm/Analysis/ScalarEvolution.h" +#include "llvm/Analysis/ScalarEvolutionExpressions.h" +#include "llvm/Analysis/TargetTransformInfo.h" +#include "llvm/Analysis/ValueTracking.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/GetElementPtrTypeIterator.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/PatternMatch.h" +#include "llvm/IR/Value.h" + +#define DEBUG_TYPE "vectorutils" + +using namespace llvm; +using namespace llvm::PatternMatch; + +/// Maximum factor for an interleaved memory access. +static cl::opt<unsigned> MaxInterleaveGroupFactor( + "max-interleave-group-factor", cl::Hidden, + cl::desc("Maximum factor for an interleaved access group (default = 8)"), + cl::init(8)); + +/// Return true if all of the intrinsic's arguments and return type are scalars +/// for the scalar form of the intrinsic, and vectors for the vector form of the +/// intrinsic (except operands that are marked as always being scalar by +/// hasVectorInstrinsicScalarOpd). +bool llvm::isTriviallyVectorizable(Intrinsic::ID ID) { + switch (ID) { + case Intrinsic::bswap: // Begin integer bit-manipulation. + case Intrinsic::bitreverse: + case Intrinsic::ctpop: + case Intrinsic::ctlz: + case Intrinsic::cttz: + case Intrinsic::fshl: + case Intrinsic::fshr: + case Intrinsic::sadd_sat: + case Intrinsic::ssub_sat: + case Intrinsic::uadd_sat: + case Intrinsic::usub_sat: + case Intrinsic::smul_fix: + case Intrinsic::smul_fix_sat: + case Intrinsic::umul_fix: + case Intrinsic::umul_fix_sat: + case Intrinsic::sqrt: // Begin floating-point. + case Intrinsic::sin: + case Intrinsic::cos: + case Intrinsic::exp: + case Intrinsic::exp2: + case Intrinsic::log: + case Intrinsic::log10: + case Intrinsic::log2: + case Intrinsic::fabs: + case Intrinsic::minnum: + case Intrinsic::maxnum: + case Intrinsic::minimum: + case Intrinsic::maximum: + case Intrinsic::copysign: + case Intrinsic::floor: + case Intrinsic::ceil: + case Intrinsic::trunc: + case Intrinsic::rint: + case Intrinsic::nearbyint: + case Intrinsic::round: + case Intrinsic::pow: + case Intrinsic::fma: + case Intrinsic::fmuladd: + case Intrinsic::powi: + case Intrinsic::canonicalize: + return true; + default: + return false; + } +} + +/// Identifies if the vector form of the intrinsic has a scalar operand. +bool llvm::hasVectorInstrinsicScalarOpd(Intrinsic::ID ID, + unsigned ScalarOpdIdx) { + switch (ID) { + case Intrinsic::ctlz: + case Intrinsic::cttz: + case Intrinsic::powi: + return (ScalarOpdIdx == 1); + case Intrinsic::smul_fix: + case Intrinsic::smul_fix_sat: + case Intrinsic::umul_fix: + case Intrinsic::umul_fix_sat: + return (ScalarOpdIdx == 2); + default: + return false; + } +} + +/// Returns intrinsic ID for call. +/// For the input call instruction it finds mapping intrinsic and returns +/// its ID, in case it does not found it return not_intrinsic. +Intrinsic::ID llvm::getVectorIntrinsicIDForCall(const CallInst *CI, + const TargetLibraryInfo *TLI) { + Intrinsic::ID ID = getIntrinsicForCallSite(CI, TLI); + if (ID == Intrinsic::not_intrinsic) + return Intrinsic::not_intrinsic; + + if (isTriviallyVectorizable(ID) || ID == Intrinsic::lifetime_start || + ID == Intrinsic::lifetime_end || ID == Intrinsic::assume || + ID == Intrinsic::sideeffect) + return ID; + return Intrinsic::not_intrinsic; +} + +/// Find the operand of the GEP that should be checked for consecutive +/// stores. This ignores trailing indices that have no effect on the final +/// pointer. +unsigned llvm::getGEPInductionOperand(const GetElementPtrInst *Gep) { + const DataLayout &DL = Gep->getModule()->getDataLayout(); + unsigned LastOperand = Gep->getNumOperands() - 1; + unsigned GEPAllocSize = DL.getTypeAllocSize(Gep->getResultElementType()); + + // Walk backwards and try to peel off zeros. + while (LastOperand > 1 && match(Gep->getOperand(LastOperand), m_Zero())) { + // Find the type we're currently indexing into. + gep_type_iterator GEPTI = gep_type_begin(Gep); + std::advance(GEPTI, LastOperand - 2); + + // If it's a type with the same allocation size as the result of the GEP we + // can peel off the zero index. + if (DL.getTypeAllocSize(GEPTI.getIndexedType()) != GEPAllocSize) + break; + --LastOperand; + } + + return LastOperand; +} + +/// If the argument is a GEP, then returns the operand identified by +/// getGEPInductionOperand. However, if there is some other non-loop-invariant +/// operand, it returns that instead. +Value *llvm::stripGetElementPtr(Value *Ptr, ScalarEvolution *SE, Loop *Lp) { + GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr); + if (!GEP) + return Ptr; + + unsigned InductionOperand = getGEPInductionOperand(GEP); + + // Check that all of the gep indices are uniform except for our induction + // operand. + for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) + if (i != InductionOperand && + !SE->isLoopInvariant(SE->getSCEV(GEP->getOperand(i)), Lp)) + return Ptr; + return GEP->getOperand(InductionOperand); +} + +/// If a value has only one user that is a CastInst, return it. +Value *llvm::getUniqueCastUse(Value *Ptr, Loop *Lp, Type *Ty) { + Value *UniqueCast = nullptr; + for (User *U : Ptr->users()) { + CastInst *CI = dyn_cast<CastInst>(U); + if (CI && CI->getType() == Ty) { + if (!UniqueCast) + UniqueCast = CI; + else + return nullptr; + } + } + return UniqueCast; +} + +/// Get the stride of a pointer access in a loop. Looks for symbolic +/// strides "a[i*stride]". Returns the symbolic stride, or null otherwise. +Value *llvm::getStrideFromPointer(Value *Ptr, ScalarEvolution *SE, Loop *Lp) { + auto *PtrTy = dyn_cast<PointerType>(Ptr->getType()); + if (!PtrTy || PtrTy->isAggregateType()) + return nullptr; + + // Try to remove a gep instruction to make the pointer (actually index at this + // point) easier analyzable. If OrigPtr is equal to Ptr we are analyzing the + // pointer, otherwise, we are analyzing the index. + Value *OrigPtr = Ptr; + + // The size of the pointer access. + int64_t PtrAccessSize = 1; + + Ptr = stripGetElementPtr(Ptr, SE, Lp); + const SCEV *V = SE->getSCEV(Ptr); + + if (Ptr != OrigPtr) + // Strip off casts. + while (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(V)) + V = C->getOperand(); + + const SCEVAddRecExpr *S = dyn_cast<SCEVAddRecExpr>(V); + if (!S) + return nullptr; + + V = S->getStepRecurrence(*SE); + if (!V) + return nullptr; + + // Strip off the size of access multiplication if we are still analyzing the + // pointer. + if (OrigPtr == Ptr) { + if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(V)) { + if (M->getOperand(0)->getSCEVType() != scConstant) + return nullptr; + + const APInt &APStepVal = cast<SCEVConstant>(M->getOperand(0))->getAPInt(); + + // Huge step value - give up. + if (APStepVal.getBitWidth() > 64) + return nullptr; + + int64_t StepVal = APStepVal.getSExtValue(); + if (PtrAccessSize != StepVal) + return nullptr; + V = M->getOperand(1); + } + } + + // Strip off casts. + Type *StripedOffRecurrenceCast = nullptr; + if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(V)) { + StripedOffRecurrenceCast = C->getType(); + V = C->getOperand(); + } + + // Look for the loop invariant symbolic value. + const SCEVUnknown *U = dyn_cast<SCEVUnknown>(V); + if (!U) + return nullptr; + + Value *Stride = U->getValue(); + if (!Lp->isLoopInvariant(Stride)) + return nullptr; + + // If we have stripped off the recurrence cast we have to make sure that we + // return the value that is used in this loop so that we can replace it later. + if (StripedOffRecurrenceCast) + Stride = getUniqueCastUse(Stride, Lp, StripedOffRecurrenceCast); + + return Stride; +} + +/// Given a vector and an element number, see if the scalar value is +/// already around as a register, for example if it were inserted then extracted +/// from the vector. +Value *llvm::findScalarElement(Value *V, unsigned EltNo) { + assert(V->getType()->isVectorTy() && "Not looking at a vector?"); + VectorType *VTy = cast<VectorType>(V->getType()); + unsigned Width = VTy->getNumElements(); + if (EltNo >= Width) // Out of range access. + return UndefValue::get(VTy->getElementType()); + + if (Constant *C = dyn_cast<Constant>(V)) + return C->getAggregateElement(EltNo); + + if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) { + // If this is an insert to a variable element, we don't know what it is. + if (!isa<ConstantInt>(III->getOperand(2))) + return nullptr; + unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue(); + + // If this is an insert to the element we are looking for, return the + // inserted value. + if (EltNo == IIElt) + return III->getOperand(1); + + // Otherwise, the insertelement doesn't modify the value, recurse on its + // vector input. + return findScalarElement(III->getOperand(0), EltNo); + } + + if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) { + unsigned LHSWidth = SVI->getOperand(0)->getType()->getVectorNumElements(); + int InEl = SVI->getMaskValue(EltNo); + if (InEl < 0) + return UndefValue::get(VTy->getElementType()); + if (InEl < (int)LHSWidth) + return findScalarElement(SVI->getOperand(0), InEl); + return findScalarElement(SVI->getOperand(1), InEl - LHSWidth); + } + + // Extract a value from a vector add operation with a constant zero. + // TODO: Use getBinOpIdentity() to generalize this. + Value *Val; Constant *C; + if (match(V, m_Add(m_Value(Val), m_Constant(C)))) + if (Constant *Elt = C->getAggregateElement(EltNo)) + if (Elt->isNullValue()) + return findScalarElement(Val, EltNo); + + // Otherwise, we don't know. + return nullptr; +} + +/// Get splat value if the input is a splat vector or return nullptr. +/// This function is not fully general. It checks only 2 cases: +/// the input value is (1) a splat constant vector or (2) a sequence +/// of instructions that broadcasts a scalar at element 0. +const llvm::Value *llvm::getSplatValue(const Value *V) { + if (isa<VectorType>(V->getType())) + if (auto *C = dyn_cast<Constant>(V)) + return C->getSplatValue(); + + // shuf (inselt ?, Splat, 0), ?, <0, undef, 0, ...> + Value *Splat; + if (match(V, m_ShuffleVector(m_InsertElement(m_Value(), m_Value(Splat), + m_ZeroInt()), + m_Value(), m_ZeroInt()))) + return Splat; + + return nullptr; +} + +// This setting is based on its counterpart in value tracking, but it could be +// adjusted if needed. +const unsigned MaxDepth = 6; + +bool llvm::isSplatValue(const Value *V, unsigned Depth) { + assert(Depth <= MaxDepth && "Limit Search Depth"); + + if (isa<VectorType>(V->getType())) { + if (isa<UndefValue>(V)) + return true; + // FIXME: Constant splat analysis does not allow undef elements. + if (auto *C = dyn_cast<Constant>(V)) + return C->getSplatValue() != nullptr; + } + + // FIXME: Constant splat analysis does not allow undef elements. + Constant *Mask; + if (match(V, m_ShuffleVector(m_Value(), m_Value(), m_Constant(Mask)))) + return Mask->getSplatValue() != nullptr; + + // The remaining tests are all recursive, so bail out if we hit the limit. + if (Depth++ == MaxDepth) + return false; + + // If both operands of a binop are splats, the result is a splat. + Value *X, *Y, *Z; + if (match(V, m_BinOp(m_Value(X), m_Value(Y)))) + return isSplatValue(X, Depth) && isSplatValue(Y, Depth); + + // If all operands of a select are splats, the result is a splat. + if (match(V, m_Select(m_Value(X), m_Value(Y), m_Value(Z)))) + return isSplatValue(X, Depth) && isSplatValue(Y, Depth) && + isSplatValue(Z, Depth); + + // TODO: Add support for unary ops (fneg), casts, intrinsics (overflow ops). + + return false; +} + +MapVector<Instruction *, uint64_t> +llvm::computeMinimumValueSizes(ArrayRef<BasicBlock *> Blocks, DemandedBits &DB, + const TargetTransformInfo *TTI) { + + // DemandedBits will give us every value's live-out bits. But we want + // to ensure no extra casts would need to be inserted, so every DAG + // of connected values must have the same minimum bitwidth. + EquivalenceClasses<Value *> ECs; + SmallVector<Value *, 16> Worklist; + SmallPtrSet<Value *, 4> Roots; + SmallPtrSet<Value *, 16> Visited; + DenseMap<Value *, uint64_t> DBits; + SmallPtrSet<Instruction *, 4> InstructionSet; + MapVector<Instruction *, uint64_t> MinBWs; + + // Determine the roots. We work bottom-up, from truncs or icmps. + bool SeenExtFromIllegalType = false; + for (auto *BB : Blocks) + for (auto &I : *BB) { + InstructionSet.insert(&I); + + if (TTI && (isa<ZExtInst>(&I) || isa<SExtInst>(&I)) && + !TTI->isTypeLegal(I.getOperand(0)->getType())) + SeenExtFromIllegalType = true; + + // Only deal with non-vector integers up to 64-bits wide. + if ((isa<TruncInst>(&I) || isa<ICmpInst>(&I)) && + !I.getType()->isVectorTy() && + I.getOperand(0)->getType()->getScalarSizeInBits() <= 64) { + // Don't make work for ourselves. If we know the loaded type is legal, + // don't add it to the worklist. + if (TTI && isa<TruncInst>(&I) && TTI->isTypeLegal(I.getType())) + continue; + + Worklist.push_back(&I); + Roots.insert(&I); + } + } + // Early exit. + if (Worklist.empty() || (TTI && !SeenExtFromIllegalType)) + return MinBWs; + + // Now proceed breadth-first, unioning values together. + while (!Worklist.empty()) { + Value *Val = Worklist.pop_back_val(); + Value *Leader = ECs.getOrInsertLeaderValue(Val); + + if (Visited.count(Val)) + continue; + Visited.insert(Val); + + // Non-instructions terminate a chain successfully. + if (!isa<Instruction>(Val)) + continue; + Instruction *I = cast<Instruction>(Val); + + // If we encounter a type that is larger than 64 bits, we can't represent + // it so bail out. + if (DB.getDemandedBits(I).getBitWidth() > 64) + return MapVector<Instruction *, uint64_t>(); + + uint64_t V = DB.getDemandedBits(I).getZExtValue(); + DBits[Leader] |= V; + DBits[I] = V; + + // Casts, loads and instructions outside of our range terminate a chain + // successfully. + if (isa<SExtInst>(I) || isa<ZExtInst>(I) || isa<LoadInst>(I) || + !InstructionSet.count(I)) + continue; + + // Unsafe casts terminate a chain unsuccessfully. We can't do anything + // useful with bitcasts, ptrtoints or inttoptrs and it'd be unsafe to + // transform anything that relies on them. + if (isa<BitCastInst>(I) || isa<PtrToIntInst>(I) || isa<IntToPtrInst>(I) || + !I->getType()->isIntegerTy()) { + DBits[Leader] |= ~0ULL; + continue; + } + + // We don't modify the types of PHIs. Reductions will already have been + // truncated if possible, and inductions' sizes will have been chosen by + // indvars. + if (isa<PHINode>(I)) + continue; + + if (DBits[Leader] == ~0ULL) + // All bits demanded, no point continuing. + continue; + + for (Value *O : cast<User>(I)->operands()) { + ECs.unionSets(Leader, O); + Worklist.push_back(O); + } + } + + // Now we've discovered all values, walk them to see if there are + // any users we didn't see. If there are, we can't optimize that + // chain. + for (auto &I : DBits) + for (auto *U : I.first->users()) + if (U->getType()->isIntegerTy() && DBits.count(U) == 0) + DBits[ECs.getOrInsertLeaderValue(I.first)] |= ~0ULL; + + for (auto I = ECs.begin(), E = ECs.end(); I != E; ++I) { + uint64_t LeaderDemandedBits = 0; + for (auto MI = ECs.member_begin(I), ME = ECs.member_end(); MI != ME; ++MI) + LeaderDemandedBits |= DBits[*MI]; + + uint64_t MinBW = (sizeof(LeaderDemandedBits) * 8) - + llvm::countLeadingZeros(LeaderDemandedBits); + // Round up to a power of 2 + if (!isPowerOf2_64((uint64_t)MinBW)) + MinBW = NextPowerOf2(MinBW); + + // We don't modify the types of PHIs. Reductions will already have been + // truncated if possible, and inductions' sizes will have been chosen by + // indvars. + // If we are required to shrink a PHI, abandon this entire equivalence class. + bool Abort = false; + for (auto MI = ECs.member_begin(I), ME = ECs.member_end(); MI != ME; ++MI) + if (isa<PHINode>(*MI) && MinBW < (*MI)->getType()->getScalarSizeInBits()) { + Abort = true; + break; + } + if (Abort) + continue; + + for (auto MI = ECs.member_begin(I), ME = ECs.member_end(); MI != ME; ++MI) { + if (!isa<Instruction>(*MI)) + continue; + Type *Ty = (*MI)->getType(); + if (Roots.count(*MI)) + Ty = cast<Instruction>(*MI)->getOperand(0)->getType(); + if (MinBW < Ty->getScalarSizeInBits()) + MinBWs[cast<Instruction>(*MI)] = MinBW; + } + } + + return MinBWs; +} + +/// Add all access groups in @p AccGroups to @p List. +template <typename ListT> +static void addToAccessGroupList(ListT &List, MDNode *AccGroups) { + // Interpret an access group as a list containing itself. + if (AccGroups->getNumOperands() == 0) { + assert(isValidAsAccessGroup(AccGroups) && "Node must be an access group"); + List.insert(AccGroups); + return; + } + + for (auto &AccGroupListOp : AccGroups->operands()) { + auto *Item = cast<MDNode>(AccGroupListOp.get()); + assert(isValidAsAccessGroup(Item) && "List item must be an access group"); + List.insert(Item); + } +} + +MDNode *llvm::uniteAccessGroups(MDNode *AccGroups1, MDNode *AccGroups2) { + if (!AccGroups1) + return AccGroups2; + if (!AccGroups2) + return AccGroups1; + if (AccGroups1 == AccGroups2) + return AccGroups1; + + SmallSetVector<Metadata *, 4> Union; + addToAccessGroupList(Union, AccGroups1); + addToAccessGroupList(Union, AccGroups2); + + if (Union.size() == 0) + return nullptr; + if (Union.size() == 1) + return cast<MDNode>(Union.front()); + + LLVMContext &Ctx = AccGroups1->getContext(); + return MDNode::get(Ctx, Union.getArrayRef()); +} + +MDNode *llvm::intersectAccessGroups(const Instruction *Inst1, + const Instruction *Inst2) { + bool MayAccessMem1 = Inst1->mayReadOrWriteMemory(); + bool MayAccessMem2 = Inst2->mayReadOrWriteMemory(); + + if (!MayAccessMem1 && !MayAccessMem2) + return nullptr; + if (!MayAccessMem1) + return Inst2->getMetadata(LLVMContext::MD_access_group); + if (!MayAccessMem2) + return Inst1->getMetadata(LLVMContext::MD_access_group); + + MDNode *MD1 = Inst1->getMetadata(LLVMContext::MD_access_group); + MDNode *MD2 = Inst2->getMetadata(LLVMContext::MD_access_group); + if (!MD1 || !MD2) + return nullptr; + if (MD1 == MD2) + return MD1; + + // Use set for scalable 'contains' check. + SmallPtrSet<Metadata *, 4> AccGroupSet2; + addToAccessGroupList(AccGroupSet2, MD2); + + SmallVector<Metadata *, 4> Intersection; + if (MD1->getNumOperands() == 0) { + assert(isValidAsAccessGroup(MD1) && "Node must be an access group"); + if (AccGroupSet2.count(MD1)) + Intersection.push_back(MD1); + } else { + for (const MDOperand &Node : MD1->operands()) { + auto *Item = cast<MDNode>(Node.get()); + assert(isValidAsAccessGroup(Item) && "List item must be an access group"); + if (AccGroupSet2.count(Item)) + Intersection.push_back(Item); + } + } + + if (Intersection.size() == 0) + return nullptr; + if (Intersection.size() == 1) + return cast<MDNode>(Intersection.front()); + + LLVMContext &Ctx = Inst1->getContext(); + return MDNode::get(Ctx, Intersection); +} + +/// \returns \p I after propagating metadata from \p VL. +Instruction *llvm::propagateMetadata(Instruction *Inst, ArrayRef<Value *> VL) { + Instruction *I0 = cast<Instruction>(VL[0]); + SmallVector<std::pair<unsigned, MDNode *>, 4> Metadata; + I0->getAllMetadataOtherThanDebugLoc(Metadata); + + for (auto Kind : {LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope, + LLVMContext::MD_noalias, LLVMContext::MD_fpmath, + LLVMContext::MD_nontemporal, LLVMContext::MD_invariant_load, + LLVMContext::MD_access_group}) { + MDNode *MD = I0->getMetadata(Kind); + + for (int J = 1, E = VL.size(); MD && J != E; ++J) { + const Instruction *IJ = cast<Instruction>(VL[J]); + MDNode *IMD = IJ->getMetadata(Kind); + switch (Kind) { + case LLVMContext::MD_tbaa: + MD = MDNode::getMostGenericTBAA(MD, IMD); + break; + case LLVMContext::MD_alias_scope: + MD = MDNode::getMostGenericAliasScope(MD, IMD); + break; + case LLVMContext::MD_fpmath: + MD = MDNode::getMostGenericFPMath(MD, IMD); + break; + case LLVMContext::MD_noalias: + case LLVMContext::MD_nontemporal: + case LLVMContext::MD_invariant_load: + MD = MDNode::intersect(MD, IMD); + break; + case LLVMContext::MD_access_group: + MD = intersectAccessGroups(Inst, IJ); + break; + default: + llvm_unreachable("unhandled metadata"); + } + } + + Inst->setMetadata(Kind, MD); + } + + return Inst; +} + +Constant * +llvm::createBitMaskForGaps(IRBuilder<> &Builder, unsigned VF, + const InterleaveGroup<Instruction> &Group) { + // All 1's means mask is not needed. + if (Group.getNumMembers() == Group.getFactor()) + return nullptr; + + // TODO: support reversed access. + assert(!Group.isReverse() && "Reversed group not supported."); + + SmallVector<Constant *, 16> Mask; + for (unsigned i = 0; i < VF; i++) + for (unsigned j = 0; j < Group.getFactor(); ++j) { + unsigned HasMember = Group.getMember(j) ? 1 : 0; + Mask.push_back(Builder.getInt1(HasMember)); + } + + return ConstantVector::get(Mask); +} + +Constant *llvm::createReplicatedMask(IRBuilder<> &Builder, + unsigned ReplicationFactor, unsigned VF) { + SmallVector<Constant *, 16> MaskVec; + for (unsigned i = 0; i < VF; i++) + for (unsigned j = 0; j < ReplicationFactor; j++) + MaskVec.push_back(Builder.getInt32(i)); + + return ConstantVector::get(MaskVec); +} + +Constant *llvm::createInterleaveMask(IRBuilder<> &Builder, unsigned VF, + unsigned NumVecs) { + SmallVector<Constant *, 16> Mask; + for (unsigned i = 0; i < VF; i++) + for (unsigned j = 0; j < NumVecs; j++) + Mask.push_back(Builder.getInt32(j * VF + i)); + + return ConstantVector::get(Mask); +} + +Constant *llvm::createStrideMask(IRBuilder<> &Builder, unsigned Start, + unsigned Stride, unsigned VF) { + SmallVector<Constant *, 16> Mask; + for (unsigned i = 0; i < VF; i++) + Mask.push_back(Builder.getInt32(Start + i * Stride)); + + return ConstantVector::get(Mask); +} + +Constant *llvm::createSequentialMask(IRBuilder<> &Builder, unsigned Start, + unsigned NumInts, unsigned NumUndefs) { + SmallVector<Constant *, 16> Mask; + for (unsigned i = 0; i < NumInts; i++) + Mask.push_back(Builder.getInt32(Start + i)); + + Constant *Undef = UndefValue::get(Builder.getInt32Ty()); + for (unsigned i = 0; i < NumUndefs; i++) + Mask.push_back(Undef); + + return ConstantVector::get(Mask); +} + +/// A helper function for concatenating vectors. This function concatenates two +/// vectors having the same element type. If the second vector has fewer +/// elements than the first, it is padded with undefs. +static Value *concatenateTwoVectors(IRBuilder<> &Builder, Value *V1, + Value *V2) { + VectorType *VecTy1 = dyn_cast<VectorType>(V1->getType()); + VectorType *VecTy2 = dyn_cast<VectorType>(V2->getType()); + assert(VecTy1 && VecTy2 && + VecTy1->getScalarType() == VecTy2->getScalarType() && + "Expect two vectors with the same element type"); + + unsigned NumElts1 = VecTy1->getNumElements(); + unsigned NumElts2 = VecTy2->getNumElements(); + assert(NumElts1 >= NumElts2 && "Unexpect the first vector has less elements"); + + if (NumElts1 > NumElts2) { + // Extend with UNDEFs. + Constant *ExtMask = + createSequentialMask(Builder, 0, NumElts2, NumElts1 - NumElts2); + V2 = Builder.CreateShuffleVector(V2, UndefValue::get(VecTy2), ExtMask); + } + + Constant *Mask = createSequentialMask(Builder, 0, NumElts1 + NumElts2, 0); + return Builder.CreateShuffleVector(V1, V2, Mask); +} + +Value *llvm::concatenateVectors(IRBuilder<> &Builder, ArrayRef<Value *> Vecs) { + unsigned NumVecs = Vecs.size(); + assert(NumVecs > 1 && "Should be at least two vectors"); + + SmallVector<Value *, 8> ResList; + ResList.append(Vecs.begin(), Vecs.end()); + do { + SmallVector<Value *, 8> TmpList; + for (unsigned i = 0; i < NumVecs - 1; i += 2) { + Value *V0 = ResList[i], *V1 = ResList[i + 1]; + assert((V0->getType() == V1->getType() || i == NumVecs - 2) && + "Only the last vector may have a different type"); + + TmpList.push_back(concatenateTwoVectors(Builder, V0, V1)); + } + + // Push the last vector if the total number of vectors is odd. + if (NumVecs % 2 != 0) + TmpList.push_back(ResList[NumVecs - 1]); + + ResList = TmpList; + NumVecs = ResList.size(); + } while (NumVecs > 1); + + return ResList[0]; +} + +bool llvm::maskIsAllZeroOrUndef(Value *Mask) { + auto *ConstMask = dyn_cast<Constant>(Mask); + if (!ConstMask) + return false; + if (ConstMask->isNullValue() || isa<UndefValue>(ConstMask)) + return true; + for (unsigned I = 0, E = ConstMask->getType()->getVectorNumElements(); I != E; + ++I) { + if (auto *MaskElt = ConstMask->getAggregateElement(I)) + if (MaskElt->isNullValue() || isa<UndefValue>(MaskElt)) + continue; + return false; + } + return true; +} + + +bool llvm::maskIsAllOneOrUndef(Value *Mask) { + auto *ConstMask = dyn_cast<Constant>(Mask); + if (!ConstMask) + return false; + if (ConstMask->isAllOnesValue() || isa<UndefValue>(ConstMask)) + return true; + for (unsigned I = 0, E = ConstMask->getType()->getVectorNumElements(); I != E; + ++I) { + if (auto *MaskElt = ConstMask->getAggregateElement(I)) + if (MaskElt->isAllOnesValue() || isa<UndefValue>(MaskElt)) + continue; + return false; + } + return true; +} + +/// TODO: This is a lot like known bits, but for +/// vectors. Is there something we can common this with? +APInt llvm::possiblyDemandedEltsInMask(Value *Mask) { + + const unsigned VWidth = cast<VectorType>(Mask->getType())->getNumElements(); + APInt DemandedElts = APInt::getAllOnesValue(VWidth); + if (auto *CV = dyn_cast<ConstantVector>(Mask)) + for (unsigned i = 0; i < VWidth; i++) + if (CV->getAggregateElement(i)->isNullValue()) + DemandedElts.clearBit(i); + return DemandedElts; +} + +bool InterleavedAccessInfo::isStrided(int Stride) { + unsigned Factor = std::abs(Stride); + return Factor >= 2 && Factor <= MaxInterleaveGroupFactor; +} + +void InterleavedAccessInfo::collectConstStrideAccesses( + MapVector<Instruction *, StrideDescriptor> &AccessStrideInfo, + const ValueToValueMap &Strides) { + auto &DL = TheLoop->getHeader()->getModule()->getDataLayout(); + + // Since it's desired that the load/store instructions be maintained in + // "program order" for the interleaved access analysis, we have to visit the + // blocks in the loop in reverse postorder (i.e., in a topological order). + // Such an ordering will ensure that any load/store that may be executed + // before a second load/store will precede the second load/store in + // AccessStrideInfo. + LoopBlocksDFS DFS(TheLoop); + DFS.perform(LI); + for (BasicBlock *BB : make_range(DFS.beginRPO(), DFS.endRPO())) + for (auto &I : *BB) { + auto *LI = dyn_cast<LoadInst>(&I); + auto *SI = dyn_cast<StoreInst>(&I); + if (!LI && !SI) + continue; + + Value *Ptr = getLoadStorePointerOperand(&I); + // We don't check wrapping here because we don't know yet if Ptr will be + // part of a full group or a group with gaps. Checking wrapping for all + // pointers (even those that end up in groups with no gaps) will be overly + // conservative. For full groups, wrapping should be ok since if we would + // wrap around the address space we would do a memory access at nullptr + // even without the transformation. The wrapping checks are therefore + // deferred until after we've formed the interleaved groups. + int64_t Stride = getPtrStride(PSE, Ptr, TheLoop, Strides, + /*Assume=*/true, /*ShouldCheckWrap=*/false); + + const SCEV *Scev = replaceSymbolicStrideSCEV(PSE, Strides, Ptr); + PointerType *PtrTy = cast<PointerType>(Ptr->getType()); + uint64_t Size = DL.getTypeAllocSize(PtrTy->getElementType()); + + // An alignment of 0 means target ABI alignment. + MaybeAlign Alignment = MaybeAlign(getLoadStoreAlignment(&I)); + if (!Alignment) + Alignment = Align(DL.getABITypeAlignment(PtrTy->getElementType())); + + AccessStrideInfo[&I] = StrideDescriptor(Stride, Scev, Size, *Alignment); + } +} + +// Analyze interleaved accesses and collect them into interleaved load and +// store groups. +// +// When generating code for an interleaved load group, we effectively hoist all +// loads in the group to the location of the first load in program order. When +// generating code for an interleaved store group, we sink all stores to the +// location of the last store. This code motion can change the order of load +// and store instructions and may break dependences. +// +// The code generation strategy mentioned above ensures that we won't violate +// any write-after-read (WAR) dependences. +// +// E.g., for the WAR dependence: a = A[i]; // (1) +// A[i] = b; // (2) +// +// The store group of (2) is always inserted at or below (2), and the load +// group of (1) is always inserted at or above (1). Thus, the instructions will +// never be reordered. All other dependences are checked to ensure the +// correctness of the instruction reordering. +// +// The algorithm visits all memory accesses in the loop in bottom-up program +// order. Program order is established by traversing the blocks in the loop in +// reverse postorder when collecting the accesses. +// +// We visit the memory accesses in bottom-up order because it can simplify the +// construction of store groups in the presence of write-after-write (WAW) +// dependences. +// +// E.g., for the WAW dependence: A[i] = a; // (1) +// A[i] = b; // (2) +// A[i + 1] = c; // (3) +// +// We will first create a store group with (3) and (2). (1) can't be added to +// this group because it and (2) are dependent. However, (1) can be grouped +// with other accesses that may precede it in program order. Note that a +// bottom-up order does not imply that WAW dependences should not be checked. +void InterleavedAccessInfo::analyzeInterleaving( + bool EnablePredicatedInterleavedMemAccesses) { + LLVM_DEBUG(dbgs() << "LV: Analyzing interleaved accesses...\n"); + const ValueToValueMap &Strides = LAI->getSymbolicStrides(); + + // Holds all accesses with a constant stride. + MapVector<Instruction *, StrideDescriptor> AccessStrideInfo; + collectConstStrideAccesses(AccessStrideInfo, Strides); + + if (AccessStrideInfo.empty()) + return; + + // Collect the dependences in the loop. + collectDependences(); + + // Holds all interleaved store groups temporarily. + SmallSetVector<InterleaveGroup<Instruction> *, 4> StoreGroups; + // Holds all interleaved load groups temporarily. + SmallSetVector<InterleaveGroup<Instruction> *, 4> LoadGroups; + + // Search in bottom-up program order for pairs of accesses (A and B) that can + // form interleaved load or store groups. In the algorithm below, access A + // precedes access B in program order. We initialize a group for B in the + // outer loop of the algorithm, and then in the inner loop, we attempt to + // insert each A into B's group if: + // + // 1. A and B have the same stride, + // 2. A and B have the same memory object size, and + // 3. A belongs in B's group according to its distance from B. + // + // Special care is taken to ensure group formation will not break any + // dependences. + for (auto BI = AccessStrideInfo.rbegin(), E = AccessStrideInfo.rend(); + BI != E; ++BI) { + Instruction *B = BI->first; + StrideDescriptor DesB = BI->second; + + // Initialize a group for B if it has an allowable stride. Even if we don't + // create a group for B, we continue with the bottom-up algorithm to ensure + // we don't break any of B's dependences. + InterleaveGroup<Instruction> *Group = nullptr; + if (isStrided(DesB.Stride) && + (!isPredicated(B->getParent()) || EnablePredicatedInterleavedMemAccesses)) { + Group = getInterleaveGroup(B); + if (!Group) { + LLVM_DEBUG(dbgs() << "LV: Creating an interleave group with:" << *B + << '\n'); + Group = createInterleaveGroup(B, DesB.Stride, DesB.Alignment); + } + if (B->mayWriteToMemory()) + StoreGroups.insert(Group); + else + LoadGroups.insert(Group); + } + + for (auto AI = std::next(BI); AI != E; ++AI) { + Instruction *A = AI->first; + StrideDescriptor DesA = AI->second; + + // Our code motion strategy implies that we can't have dependences + // between accesses in an interleaved group and other accesses located + // between the first and last member of the group. Note that this also + // means that a group can't have more than one member at a given offset. + // The accesses in a group can have dependences with other accesses, but + // we must ensure we don't extend the boundaries of the group such that + // we encompass those dependent accesses. + // + // For example, assume we have the sequence of accesses shown below in a + // stride-2 loop: + // + // (1, 2) is a group | A[i] = a; // (1) + // | A[i-1] = b; // (2) | + // A[i-3] = c; // (3) + // A[i] = d; // (4) | (2, 4) is not a group + // + // Because accesses (2) and (3) are dependent, we can group (2) with (1) + // but not with (4). If we did, the dependent access (3) would be within + // the boundaries of the (2, 4) group. + if (!canReorderMemAccessesForInterleavedGroups(&*AI, &*BI)) { + // If a dependence exists and A is already in a group, we know that A + // must be a store since A precedes B and WAR dependences are allowed. + // Thus, A would be sunk below B. We release A's group to prevent this + // illegal code motion. A will then be free to form another group with + // instructions that precede it. + if (isInterleaved(A)) { + InterleaveGroup<Instruction> *StoreGroup = getInterleaveGroup(A); + + LLVM_DEBUG(dbgs() << "LV: Invalidated store group due to " + "dependence between " << *A << " and "<< *B << '\n'); + + StoreGroups.remove(StoreGroup); + releaseGroup(StoreGroup); + } + + // If a dependence exists and A is not already in a group (or it was + // and we just released it), B might be hoisted above A (if B is a + // load) or another store might be sunk below A (if B is a store). In + // either case, we can't add additional instructions to B's group. B + // will only form a group with instructions that it precedes. + break; + } + + // At this point, we've checked for illegal code motion. If either A or B + // isn't strided, there's nothing left to do. + if (!isStrided(DesA.Stride) || !isStrided(DesB.Stride)) + continue; + + // Ignore A if it's already in a group or isn't the same kind of memory + // operation as B. + // Note that mayReadFromMemory() isn't mutually exclusive to + // mayWriteToMemory in the case of atomic loads. We shouldn't see those + // here, canVectorizeMemory() should have returned false - except for the + // case we asked for optimization remarks. + if (isInterleaved(A) || + (A->mayReadFromMemory() != B->mayReadFromMemory()) || + (A->mayWriteToMemory() != B->mayWriteToMemory())) + continue; + + // Check rules 1 and 2. Ignore A if its stride or size is different from + // that of B. + if (DesA.Stride != DesB.Stride || DesA.Size != DesB.Size) + continue; + + // Ignore A if the memory object of A and B don't belong to the same + // address space + if (getLoadStoreAddressSpace(A) != getLoadStoreAddressSpace(B)) + continue; + + // Calculate the distance from A to B. + const SCEVConstant *DistToB = dyn_cast<SCEVConstant>( + PSE.getSE()->getMinusSCEV(DesA.Scev, DesB.Scev)); + if (!DistToB) + continue; + int64_t DistanceToB = DistToB->getAPInt().getSExtValue(); + + // Check rule 3. Ignore A if its distance to B is not a multiple of the + // size. + if (DistanceToB % static_cast<int64_t>(DesB.Size)) + continue; + + // All members of a predicated interleave-group must have the same predicate, + // and currently must reside in the same BB. + BasicBlock *BlockA = A->getParent(); + BasicBlock *BlockB = B->getParent(); + if ((isPredicated(BlockA) || isPredicated(BlockB)) && + (!EnablePredicatedInterleavedMemAccesses || BlockA != BlockB)) + continue; + + // The index of A is the index of B plus A's distance to B in multiples + // of the size. + int IndexA = + Group->getIndex(B) + DistanceToB / static_cast<int64_t>(DesB.Size); + + // Try to insert A into B's group. + if (Group->insertMember(A, IndexA, DesA.Alignment)) { + LLVM_DEBUG(dbgs() << "LV: Inserted:" << *A << '\n' + << " into the interleave group with" << *B + << '\n'); + InterleaveGroupMap[A] = Group; + + // Set the first load in program order as the insert position. + if (A->mayReadFromMemory()) + Group->setInsertPos(A); + } + } // Iteration over A accesses. + } // Iteration over B accesses. + + // Remove interleaved store groups with gaps. + for (auto *Group : StoreGroups) + if (Group->getNumMembers() != Group->getFactor()) { + LLVM_DEBUG( + dbgs() << "LV: Invalidate candidate interleaved store group due " + "to gaps.\n"); + releaseGroup(Group); + } + // Remove interleaved groups with gaps (currently only loads) whose memory + // accesses may wrap around. We have to revisit the getPtrStride analysis, + // this time with ShouldCheckWrap=true, since collectConstStrideAccesses does + // not check wrapping (see documentation there). + // FORNOW we use Assume=false; + // TODO: Change to Assume=true but making sure we don't exceed the threshold + // of runtime SCEV assumptions checks (thereby potentially failing to + // vectorize altogether). + // Additional optional optimizations: + // TODO: If we are peeling the loop and we know that the first pointer doesn't + // wrap then we can deduce that all pointers in the group don't wrap. + // This means that we can forcefully peel the loop in order to only have to + // check the first pointer for no-wrap. When we'll change to use Assume=true + // we'll only need at most one runtime check per interleaved group. + for (auto *Group : LoadGroups) { + // Case 1: A full group. Can Skip the checks; For full groups, if the wide + // load would wrap around the address space we would do a memory access at + // nullptr even without the transformation. + if (Group->getNumMembers() == Group->getFactor()) + continue; + + // Case 2: If first and last members of the group don't wrap this implies + // that all the pointers in the group don't wrap. + // So we check only group member 0 (which is always guaranteed to exist), + // and group member Factor - 1; If the latter doesn't exist we rely on + // peeling (if it is a non-reversed accsess -- see Case 3). + Value *FirstMemberPtr = getLoadStorePointerOperand(Group->getMember(0)); + if (!getPtrStride(PSE, FirstMemberPtr, TheLoop, Strides, /*Assume=*/false, + /*ShouldCheckWrap=*/true)) { + LLVM_DEBUG( + dbgs() << "LV: Invalidate candidate interleaved group due to " + "first group member potentially pointer-wrapping.\n"); + releaseGroup(Group); + continue; + } + Instruction *LastMember = Group->getMember(Group->getFactor() - 1); + if (LastMember) { + Value *LastMemberPtr = getLoadStorePointerOperand(LastMember); + if (!getPtrStride(PSE, LastMemberPtr, TheLoop, Strides, /*Assume=*/false, + /*ShouldCheckWrap=*/true)) { + LLVM_DEBUG( + dbgs() << "LV: Invalidate candidate interleaved group due to " + "last group member potentially pointer-wrapping.\n"); + releaseGroup(Group); + } + } else { + // Case 3: A non-reversed interleaved load group with gaps: We need + // to execute at least one scalar epilogue iteration. This will ensure + // we don't speculatively access memory out-of-bounds. We only need + // to look for a member at index factor - 1, since every group must have + // a member at index zero. + if (Group->isReverse()) { + LLVM_DEBUG( + dbgs() << "LV: Invalidate candidate interleaved group due to " + "a reverse access with gaps.\n"); + releaseGroup(Group); + continue; + } + LLVM_DEBUG( + dbgs() << "LV: Interleaved group requires epilogue iteration.\n"); + RequiresScalarEpilogue = true; + } + } +} + +void InterleavedAccessInfo::invalidateGroupsRequiringScalarEpilogue() { + // If no group had triggered the requirement to create an epilogue loop, + // there is nothing to do. + if (!requiresScalarEpilogue()) + return; + + // Avoid releasing a Group twice. + SmallPtrSet<InterleaveGroup<Instruction> *, 4> DelSet; + for (auto &I : InterleaveGroupMap) { + InterleaveGroup<Instruction> *Group = I.second; + if (Group->requiresScalarEpilogue()) + DelSet.insert(Group); + } + for (auto *Ptr : DelSet) { + LLVM_DEBUG( + dbgs() + << "LV: Invalidate candidate interleaved group due to gaps that " + "require a scalar epilogue (not allowed under optsize) and cannot " + "be masked (not enabled). \n"); + releaseGroup(Ptr); + } + + RequiresScalarEpilogue = false; +} + +template <typename InstT> +void InterleaveGroup<InstT>::addMetadata(InstT *NewInst) const { + llvm_unreachable("addMetadata can only be used for Instruction"); +} + +namespace llvm { +template <> +void InterleaveGroup<Instruction>::addMetadata(Instruction *NewInst) const { + SmallVector<Value *, 4> VL; + std::transform(Members.begin(), Members.end(), std::back_inserter(VL), + [](std::pair<int, Instruction *> p) { return p.second; }); + propagateMetadata(NewInst, VL); +} +} |