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diff --git a/contrib/llvm/lib/Transforms/Scalar/LoopDataPrefetch.cpp b/contrib/llvm/lib/Transforms/Scalar/LoopDataPrefetch.cpp
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-//===-------- LoopDataPrefetch.cpp - Loop Data Prefetching Pass -----------===//
-//
-// 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 implements a Loop Data Prefetching Pass.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Transforms/Scalar/LoopDataPrefetch.h"
-
-#define DEBUG_TYPE "loop-data-prefetch"
-#include "llvm/ADT/DepthFirstIterator.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/AssumptionCache.h"
-#include "llvm/Analysis/CodeMetrics.h"
-#include "llvm/Analysis/LoopInfo.h"
-#include "llvm/Analysis/OptimizationRemarkEmitter.h"
-#include "llvm/Analysis/ScalarEvolution.h"
-#include "llvm/Analysis/ScalarEvolutionExpander.h"
-#include "llvm/Analysis/ScalarEvolutionExpressions.h"
-#include "llvm/Analysis/TargetTransformInfo.h"
-#include "llvm/IR/CFG.h"
-#include "llvm/IR/Dominators.h"
-#include "llvm/IR/Function.h"
-#include "llvm/IR/Module.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Transforms/Scalar.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/ValueMapper.h"
-using namespace llvm;
-
-// By default, we limit this to creating 16 PHIs (which is a little over half
-// of the allocatable register set).
-static cl::opt<bool>
-PrefetchWrites("loop-prefetch-writes", cl::Hidden, cl::init(false),
- cl::desc("Prefetch write addresses"));
-
-static cl::opt<unsigned>
- PrefetchDistance("prefetch-distance",
- cl::desc("Number of instructions to prefetch ahead"),
- cl::Hidden);
-
-static cl::opt<unsigned>
- MinPrefetchStride("min-prefetch-stride",
- cl::desc("Min stride to add prefetches"), cl::Hidden);
-
-static cl::opt<unsigned> MaxPrefetchIterationsAhead(
- "max-prefetch-iters-ahead",
- cl::desc("Max number of iterations to prefetch ahead"), cl::Hidden);
-
-STATISTIC(NumPrefetches, "Number of prefetches inserted");
-
-namespace {
-
-/// Loop prefetch implementation class.
-class LoopDataPrefetch {
-public:
- LoopDataPrefetch(AssumptionCache *AC, LoopInfo *LI, ScalarEvolution *SE,
- const TargetTransformInfo *TTI,
- OptimizationRemarkEmitter *ORE)
- : AC(AC), LI(LI), SE(SE), TTI(TTI), ORE(ORE) {}
-
- bool run();
-
-private:
- bool runOnLoop(Loop *L);
-
- /// Check if the stride of the accesses is large enough to
- /// warrant a prefetch.
- bool isStrideLargeEnough(const SCEVAddRecExpr *AR);
-
- unsigned getMinPrefetchStride() {
- if (MinPrefetchStride.getNumOccurrences() > 0)
- return MinPrefetchStride;
- return TTI->getMinPrefetchStride();
- }
-
- unsigned getPrefetchDistance() {
- if (PrefetchDistance.getNumOccurrences() > 0)
- return PrefetchDistance;
- return TTI->getPrefetchDistance();
- }
-
- unsigned getMaxPrefetchIterationsAhead() {
- if (MaxPrefetchIterationsAhead.getNumOccurrences() > 0)
- return MaxPrefetchIterationsAhead;
- return TTI->getMaxPrefetchIterationsAhead();
- }
-
- AssumptionCache *AC;
- LoopInfo *LI;
- ScalarEvolution *SE;
- const TargetTransformInfo *TTI;
- OptimizationRemarkEmitter *ORE;
-};
-
-/// Legacy class for inserting loop data prefetches.
-class LoopDataPrefetchLegacyPass : public FunctionPass {
-public:
- static char ID; // Pass ID, replacement for typeid
- LoopDataPrefetchLegacyPass() : FunctionPass(ID) {
- initializeLoopDataPrefetchLegacyPassPass(*PassRegistry::getPassRegistry());
- }
-
- void getAnalysisUsage(AnalysisUsage &AU) const override {
- AU.addRequired<AssumptionCacheTracker>();
- AU.addPreserved<DominatorTreeWrapperPass>();
- AU.addRequired<LoopInfoWrapperPass>();
- AU.addPreserved<LoopInfoWrapperPass>();
- AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
- AU.addRequired<ScalarEvolutionWrapperPass>();
- AU.addPreserved<ScalarEvolutionWrapperPass>();
- AU.addRequired<TargetTransformInfoWrapperPass>();
- }
-
- bool runOnFunction(Function &F) override;
- };
-}
-
-char LoopDataPrefetchLegacyPass::ID = 0;
-INITIALIZE_PASS_BEGIN(LoopDataPrefetchLegacyPass, "loop-data-prefetch",
- "Loop Data Prefetch", false, false)
-INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
-INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(OptimizationRemarkEmitterWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
-INITIALIZE_PASS_END(LoopDataPrefetchLegacyPass, "loop-data-prefetch",
- "Loop Data Prefetch", false, false)
-
-FunctionPass *llvm::createLoopDataPrefetchPass() {
- return new LoopDataPrefetchLegacyPass();
-}
-
-bool LoopDataPrefetch::isStrideLargeEnough(const SCEVAddRecExpr *AR) {
- unsigned TargetMinStride = getMinPrefetchStride();
- // No need to check if any stride goes.
- if (TargetMinStride <= 1)
- return true;
-
- const auto *ConstStride = dyn_cast<SCEVConstant>(AR->getStepRecurrence(*SE));
- // If MinStride is set, don't prefetch unless we can ensure that stride is
- // larger.
- if (!ConstStride)
- return false;
-
- unsigned AbsStride = std::abs(ConstStride->getAPInt().getSExtValue());
- return TargetMinStride <= AbsStride;
-}
-
-PreservedAnalyses LoopDataPrefetchPass::run(Function &F,
- FunctionAnalysisManager &AM) {
- LoopInfo *LI = &AM.getResult<LoopAnalysis>(F);
- ScalarEvolution *SE = &AM.getResult<ScalarEvolutionAnalysis>(F);
- AssumptionCache *AC = &AM.getResult<AssumptionAnalysis>(F);
- OptimizationRemarkEmitter *ORE =
- &AM.getResult<OptimizationRemarkEmitterAnalysis>(F);
- const TargetTransformInfo *TTI = &AM.getResult<TargetIRAnalysis>(F);
-
- LoopDataPrefetch LDP(AC, LI, SE, TTI, ORE);
- bool Changed = LDP.run();
-
- if (Changed) {
- PreservedAnalyses PA;
- PA.preserve<DominatorTreeAnalysis>();
- PA.preserve<LoopAnalysis>();
- return PA;
- }
-
- return PreservedAnalyses::all();
-}
-
-bool LoopDataPrefetchLegacyPass::runOnFunction(Function &F) {
- if (skipFunction(F))
- return false;
-
- LoopInfo *LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
- ScalarEvolution *SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
- AssumptionCache *AC =
- &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
- OptimizationRemarkEmitter *ORE =
- &getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE();
- const TargetTransformInfo *TTI =
- &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
-
- LoopDataPrefetch LDP(AC, LI, SE, TTI, ORE);
- return LDP.run();
-}
-
-bool LoopDataPrefetch::run() {
- // If PrefetchDistance is not set, don't run the pass. This gives an
- // opportunity for targets to run this pass for selected subtargets only
- // (whose TTI sets PrefetchDistance).
- if (getPrefetchDistance() == 0)
- return false;
- assert(TTI->getCacheLineSize() && "Cache line size is not set for target");
-
- bool MadeChange = false;
-
- for (Loop *I : *LI)
- for (auto L = df_begin(I), LE = df_end(I); L != LE; ++L)
- MadeChange |= runOnLoop(*L);
-
- return MadeChange;
-}
-
-bool LoopDataPrefetch::runOnLoop(Loop *L) {
- bool MadeChange = false;
-
- // Only prefetch in the inner-most loop
- if (!L->empty())
- return MadeChange;
-
- SmallPtrSet<const Value *, 32> EphValues;
- CodeMetrics::collectEphemeralValues(L, AC, EphValues);
-
- // Calculate the number of iterations ahead to prefetch
- CodeMetrics Metrics;
- for (const auto BB : L->blocks()) {
- // If the loop already has prefetches, then assume that the user knows
- // what they are doing and don't add any more.
- for (auto &I : *BB)
- if (CallInst *CI = dyn_cast<CallInst>(&I))
- if (Function *F = CI->getCalledFunction())
- if (F->getIntrinsicID() == Intrinsic::prefetch)
- return MadeChange;
-
- Metrics.analyzeBasicBlock(BB, *TTI, EphValues);
- }
- unsigned LoopSize = Metrics.NumInsts;
- if (!LoopSize)
- LoopSize = 1;
-
- unsigned ItersAhead = getPrefetchDistance() / LoopSize;
- if (!ItersAhead)
- ItersAhead = 1;
-
- if (ItersAhead > getMaxPrefetchIterationsAhead())
- return MadeChange;
-
- LLVM_DEBUG(dbgs() << "Prefetching " << ItersAhead
- << " iterations ahead (loop size: " << LoopSize << ") in "
- << L->getHeader()->getParent()->getName() << ": " << *L);
-
- SmallVector<std::pair<Instruction *, const SCEVAddRecExpr *>, 16> PrefLoads;
- for (const auto BB : L->blocks()) {
- for (auto &I : *BB) {
- Value *PtrValue;
- Instruction *MemI;
-
- if (LoadInst *LMemI = dyn_cast<LoadInst>(&I)) {
- MemI = LMemI;
- PtrValue = LMemI->getPointerOperand();
- } else if (StoreInst *SMemI = dyn_cast<StoreInst>(&I)) {
- if (!PrefetchWrites) continue;
- MemI = SMemI;
- PtrValue = SMemI->getPointerOperand();
- } else continue;
-
- unsigned PtrAddrSpace = PtrValue->getType()->getPointerAddressSpace();
- if (PtrAddrSpace)
- continue;
-
- if (L->isLoopInvariant(PtrValue))
- continue;
-
- const SCEV *LSCEV = SE->getSCEV(PtrValue);
- const SCEVAddRecExpr *LSCEVAddRec = dyn_cast<SCEVAddRecExpr>(LSCEV);
- if (!LSCEVAddRec)
- continue;
-
- // Check if the stride of the accesses is large enough to warrant a
- // prefetch.
- if (!isStrideLargeEnough(LSCEVAddRec))
- continue;
-
- // We don't want to double prefetch individual cache lines. If this load
- // is known to be within one cache line of some other load that has
- // already been prefetched, then don't prefetch this one as well.
- bool DupPref = false;
- for (const auto &PrefLoad : PrefLoads) {
- const SCEV *PtrDiff = SE->getMinusSCEV(LSCEVAddRec, PrefLoad.second);
- if (const SCEVConstant *ConstPtrDiff =
- dyn_cast<SCEVConstant>(PtrDiff)) {
- int64_t PD = std::abs(ConstPtrDiff->getValue()->getSExtValue());
- if (PD < (int64_t) TTI->getCacheLineSize()) {
- DupPref = true;
- break;
- }
- }
- }
- if (DupPref)
- continue;
-
- const SCEV *NextLSCEV = SE->getAddExpr(LSCEVAddRec, SE->getMulExpr(
- SE->getConstant(LSCEVAddRec->getType(), ItersAhead),
- LSCEVAddRec->getStepRecurrence(*SE)));
- if (!isSafeToExpand(NextLSCEV, *SE))
- continue;
-
- PrefLoads.push_back(std::make_pair(MemI, LSCEVAddRec));
-
- Type *I8Ptr = Type::getInt8PtrTy(BB->getContext(), PtrAddrSpace);
- SCEVExpander SCEVE(*SE, I.getModule()->getDataLayout(), "prefaddr");
- Value *PrefPtrValue = SCEVE.expandCodeFor(NextLSCEV, I8Ptr, MemI);
-
- IRBuilder<> Builder(MemI);
- Module *M = BB->getParent()->getParent();
- Type *I32 = Type::getInt32Ty(BB->getContext());
- Function *PrefetchFunc =
- Intrinsic::getDeclaration(M, Intrinsic::prefetch);
- Builder.CreateCall(
- PrefetchFunc,
- {PrefPtrValue,
- ConstantInt::get(I32, MemI->mayReadFromMemory() ? 0 : 1),
- ConstantInt::get(I32, 3), ConstantInt::get(I32, 1)});
- ++NumPrefetches;
- LLVM_DEBUG(dbgs() << " Access: " << *PtrValue << ", SCEV: " << *LSCEV
- << "\n");
- ORE->emit([&]() {
- return OptimizationRemark(DEBUG_TYPE, "Prefetched", MemI)
- << "prefetched memory access";
- });
-
- MadeChange = true;
- }
- }
-
- return MadeChange;
-}
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