--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/Transforms/Instrumentation/PGOMemOPSizeOpt.cpp	Fri Oct 27 17:07:41 2017 +0900
@@ -0,0 +1,431 @@
+//===-- PGOMemOPSizeOpt.cpp - Optimizations based on value profiling ===//
+//
+//                      The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the transformation that optimizes memory intrinsics
+// such as memcpy using the size value profile. When memory intrinsic size
+// value profile metadata is available, a single memory intrinsic is expanded
+// to a sequence of guarded specialized versions that are called with the
+// hottest size(s), for later expansion into more optimal inline sequences.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/Analysis/BlockFrequencyInfo.h"
+#include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/Analysis/OptimizationRemarkEmitter.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/InstVisitor.h"
+#include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/Type.h"
+#include "llvm/Pass.h"
+#include "llvm/PassRegistry.h"
+#include "llvm/PassSupport.h"
+#include "llvm/ProfileData/InstrProf.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Transforms/Instrumentation.h"
+#include "llvm/Transforms/PGOInstrumentation.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include <cassert>
+#include <cstdint>
+#include <vector>
+
+using namespace llvm;
+
+#define DEBUG_TYPE "pgo-memop-opt"
+
+STATISTIC(NumOfPGOMemOPOpt, "Number of memop intrinsics optimized.");
+STATISTIC(NumOfPGOMemOPAnnotate, "Number of memop intrinsics annotated.");
+
+// The minimum call count to optimize memory intrinsic calls.
+static cl::opt<unsigned>
+    MemOPCountThreshold("pgo-memop-count-threshold", cl::Hidden, cl::ZeroOrMore,
+                        cl::init(1000),
+                        cl::desc("The minimum count to optimize memory "
+                                 "intrinsic calls"));
+
+// Command line option to disable memory intrinsic optimization. The default is
+// false. This is for debug purpose.
+static cl::opt<bool> DisableMemOPOPT("disable-memop-opt", cl::init(false),
+                                     cl::Hidden, cl::desc("Disable optimize"));
+
+// The percent threshold to optimize memory intrinsic calls.
+static cl::opt<unsigned>
+    MemOPPercentThreshold("pgo-memop-percent-threshold", cl::init(40),
+                          cl::Hidden, cl::ZeroOrMore,
+                          cl::desc("The percentage threshold for the "
+                                   "memory intrinsic calls optimization"));
+
+// Maximum number of versions for optimizing memory intrinsic call.
+static cl::opt<unsigned>
+    MemOPMaxVersion("pgo-memop-max-version", cl::init(3), cl::Hidden,
+                    cl::ZeroOrMore,
+                    cl::desc("The max version for the optimized memory "
+                             " intrinsic calls"));
+
+// Scale the counts from the annotation using the BB count value.
+static cl::opt<bool>
+    MemOPScaleCount("pgo-memop-scale-count", cl::init(true), cl::Hidden,
+                    cl::desc("Scale the memop size counts using the basic "
+                             " block count value"));
+
+// This option sets the rangge of precise profile memop sizes.
+extern cl::opt<std::string> MemOPSizeRange;
+
+// This option sets the value that groups large memop sizes
+extern cl::opt<unsigned> MemOPSizeLarge;
+
+namespace {
+class PGOMemOPSizeOptLegacyPass : public FunctionPass {
+public:
+  static char ID;
+
+  PGOMemOPSizeOptLegacyPass() : FunctionPass(ID) {
+    initializePGOMemOPSizeOptLegacyPassPass(*PassRegistry::getPassRegistry());
+  }
+
+  StringRef getPassName() const override { return "PGOMemOPSize"; }
+
+private:
+  bool runOnFunction(Function &F) override;
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<BlockFrequencyInfoWrapperPass>();
+    AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
+    AU.addPreserved<GlobalsAAWrapperPass>();
+  }
+};
+} // end anonymous namespace
+
+char PGOMemOPSizeOptLegacyPass::ID = 0;
+INITIALIZE_PASS_BEGIN(PGOMemOPSizeOptLegacyPass, "pgo-memop-opt",
+                      "Optimize memory intrinsic using its size value profile",
+                      false, false)
+INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
+INITIALIZE_PASS_END(PGOMemOPSizeOptLegacyPass, "pgo-memop-opt",
+                    "Optimize memory intrinsic using its size value profile",
+                    false, false)
+
+FunctionPass *llvm::createPGOMemOPSizeOptLegacyPass() {
+  return new PGOMemOPSizeOptLegacyPass();
+}
+
+namespace {
+class MemOPSizeOpt : public InstVisitor<MemOPSizeOpt> {
+public:
+  MemOPSizeOpt(Function &Func, BlockFrequencyInfo &BFI,
+               OptimizationRemarkEmitter &ORE)
+      : Func(Func), BFI(BFI), ORE(ORE), Changed(false) {
+    ValueDataArray =
+        llvm::make_unique<InstrProfValueData[]>(MemOPMaxVersion + 2);
+    // Get the MemOPSize range information from option MemOPSizeRange,
+    getMemOPSizeRangeFromOption(MemOPSizeRange, PreciseRangeStart,
+                                PreciseRangeLast);
+  }
+  bool isChanged() const { return Changed; }
+  void perform() {
+    WorkList.clear();
+    visit(Func);
+
+    for (auto &MI : WorkList) {
+      ++NumOfPGOMemOPAnnotate;
+      if (perform(MI)) {
+        Changed = true;
+        ++NumOfPGOMemOPOpt;
+        DEBUG(dbgs() << "MemOP call: " << MI->getCalledFunction()->getName()
+                     << "is Transformed.\n");
+      }
+    }
+  }
+
+  void visitMemIntrinsic(MemIntrinsic &MI) {
+    Value *Length = MI.getLength();
+    // Not perform on constant length calls.
+    if (dyn_cast<ConstantInt>(Length))
+      return;
+    WorkList.push_back(&MI);
+  }
+
+private:
+  Function &Func;
+  BlockFrequencyInfo &BFI;
+  OptimizationRemarkEmitter &ORE;
+  bool Changed;
+  std::vector<MemIntrinsic *> WorkList;
+  // Start of the previse range.
+  int64_t PreciseRangeStart;
+  // Last value of the previse range.
+  int64_t PreciseRangeLast;
+  // The space to read the profile annotation.
+  std::unique_ptr<InstrProfValueData[]> ValueDataArray;
+  bool perform(MemIntrinsic *MI);
+
+  // This kind shows which group the value falls in. For PreciseValue, we have
+  // the profile count for that value. LargeGroup groups the values that are in
+  // range [LargeValue, +inf). NonLargeGroup groups the rest of values.
+  enum MemOPSizeKind { PreciseValue, NonLargeGroup, LargeGroup };
+
+  MemOPSizeKind getMemOPSizeKind(int64_t Value) const {
+    if (Value == MemOPSizeLarge && MemOPSizeLarge != 0)
+      return LargeGroup;
+    if (Value == PreciseRangeLast + 1)
+      return NonLargeGroup;
+    return PreciseValue;
+  }
+};
+
+static const char *getMIName(const MemIntrinsic *MI) {
+  switch (MI->getIntrinsicID()) {
+  case Intrinsic::memcpy:
+    return "memcpy";
+  case Intrinsic::memmove:
+    return "memmove";
+  case Intrinsic::memset:
+    return "memset";
+  default:
+    return "unknown";
+  }
+}
+
+static bool isProfitable(uint64_t Count, uint64_t TotalCount) {
+  assert(Count <= TotalCount);
+  if (Count < MemOPCountThreshold)
+    return false;
+  if (Count < TotalCount * MemOPPercentThreshold / 100)
+    return false;
+  return true;
+}
+
+static inline uint64_t getScaledCount(uint64_t Count, uint64_t Num,
+                                      uint64_t Denom) {
+  if (!MemOPScaleCount)
+    return Count;
+  bool Overflowed;
+  uint64_t ScaleCount = SaturatingMultiply(Count, Num, &Overflowed);
+  return ScaleCount / Denom;
+}
+
+bool MemOPSizeOpt::perform(MemIntrinsic *MI) {
+  assert(MI);
+  if (MI->getIntrinsicID() == Intrinsic::memmove)
+    return false;
+
+  uint32_t NumVals, MaxNumPromotions = MemOPMaxVersion + 2;
+  uint64_t TotalCount;
+  if (!getValueProfDataFromInst(*MI, IPVK_MemOPSize, MaxNumPromotions,
+                                ValueDataArray.get(), NumVals, TotalCount))
+    return false;
+
+  uint64_t ActualCount = TotalCount;
+  uint64_t SavedTotalCount = TotalCount;
+  if (MemOPScaleCount) {
+    auto BBEdgeCount = BFI.getBlockProfileCount(MI->getParent());
+    if (!BBEdgeCount)
+      return false;
+    ActualCount = *BBEdgeCount;
+  }
+
+  ArrayRef<InstrProfValueData> VDs(ValueDataArray.get(), NumVals);
+  DEBUG(dbgs() << "Read one memory intrinsic profile with count " << ActualCount
+               << "\n");
+  DEBUG(
+      for (auto &VD
+           : VDs) { dbgs() << "  (" << VD.Value << "," << VD.Count << ")\n"; });
+
+  if (ActualCount < MemOPCountThreshold)
+    return false;
+  // Skip if the total value profiled count is 0, in which case we can't
+  // scale up the counts properly (and there is no profitable transformation).
+  if (TotalCount == 0)
+    return false;
+
+  TotalCount = ActualCount;
+  if (MemOPScaleCount)
+    DEBUG(dbgs() << "Scale counts: numerator = " << ActualCount
+                 << " denominator = " << SavedTotalCount << "\n");
+
+  // Keeping track of the count of the default case:
+  uint64_t RemainCount = TotalCount;
+  uint64_t SavedRemainCount = SavedTotalCount;
+  SmallVector<uint64_t, 16> SizeIds;
+  SmallVector<uint64_t, 16> CaseCounts;
+  uint64_t MaxCount = 0;
+  unsigned Version = 0;
+  // Default case is in the front -- save the slot here.
+  CaseCounts.push_back(0);
+  for (auto &VD : VDs) {
+    int64_t V = VD.Value;
+    uint64_t C = VD.Count;
+    if (MemOPScaleCount)
+      C = getScaledCount(C, ActualCount, SavedTotalCount);
+
+    // Only care precise value here.
+    if (getMemOPSizeKind(V) != PreciseValue)
+      continue;
+
+    // ValueCounts are sorted on the count. Break at the first un-profitable
+    // value.
+    if (!isProfitable(C, RemainCount))
+      break;
+
+    SizeIds.push_back(V);
+    CaseCounts.push_back(C);
+    if (C > MaxCount)
+      MaxCount = C;
+
+    assert(RemainCount >= C);
+    RemainCount -= C;
+    assert(SavedRemainCount >= VD.Count);
+    SavedRemainCount -= VD.Count;
+
+    if (++Version > MemOPMaxVersion && MemOPMaxVersion != 0)
+      break;
+  }
+
+  if (Version == 0)
+    return false;
+
+  CaseCounts[0] = RemainCount;
+  if (RemainCount > MaxCount)
+    MaxCount = RemainCount;
+
+  uint64_t SumForOpt = TotalCount - RemainCount;
+
+  DEBUG(dbgs() << "Optimize one memory intrinsic call to " << Version
+               << " Versions (covering " << SumForOpt << " out of "
+               << TotalCount << ")\n");
+
+  // mem_op(..., size)
+  // ==>
+  // switch (size) {
+  //   case s1:
+  //      mem_op(..., s1);
+  //      goto merge_bb;
+  //   case s2:
+  //      mem_op(..., s2);
+  //      goto merge_bb;
+  //   ...
+  //   default:
+  //      mem_op(..., size);
+  //      goto merge_bb;
+  // }
+  // merge_bb:
+
+  BasicBlock *BB = MI->getParent();
+  DEBUG(dbgs() << "\n\n== Basic Block Before ==\n");
+  DEBUG(dbgs() << *BB << "\n");
+  auto OrigBBFreq = BFI.getBlockFreq(BB);
+
+  BasicBlock *DefaultBB = SplitBlock(BB, MI);
+  BasicBlock::iterator It(*MI);
+  ++It;
+  assert(It != DefaultBB->end());
+  BasicBlock *MergeBB = SplitBlock(DefaultBB, &(*It));
+  MergeBB->setName("MemOP.Merge");
+  BFI.setBlockFreq(MergeBB, OrigBBFreq.getFrequency());
+  DefaultBB->setName("MemOP.Default");
+
+  auto &Ctx = Func.getContext();
+  IRBuilder<> IRB(BB);
+  BB->getTerminator()->eraseFromParent();
+  Value *SizeVar = MI->getLength();
+  SwitchInst *SI = IRB.CreateSwitch(SizeVar, DefaultBB, SizeIds.size());
+
+  // Clear the value profile data.
+  MI->setMetadata(LLVMContext::MD_prof, nullptr);
+  // If all promoted, we don't need the MD.prof metadata.
+  if (SavedRemainCount > 0 || Version != NumVals)
+    // Otherwise we need update with the un-promoted records back.
+    annotateValueSite(*Func.getParent(), *MI, VDs.slice(Version),
+                      SavedRemainCount, IPVK_MemOPSize, NumVals);
+
+  DEBUG(dbgs() << "\n\n== Basic Block After==\n");
+
+  for (uint64_t SizeId : SizeIds) {
+    BasicBlock *CaseBB = BasicBlock::Create(
+        Ctx, Twine("MemOP.Case.") + Twine(SizeId), &Func, DefaultBB);
+    Instruction *NewInst = MI->clone();
+    // Fix the argument.
+    MemIntrinsic * MemI = dyn_cast<MemIntrinsic>(NewInst);
+    IntegerType *SizeType = dyn_cast<IntegerType>(MemI->getLength()->getType());
+    assert(SizeType && "Expected integer type size argument.");
+    ConstantInt *CaseSizeId = ConstantInt::get(SizeType, SizeId);
+    MemI->setLength(CaseSizeId);
+    CaseBB->getInstList().push_back(NewInst);
+    IRBuilder<> IRBCase(CaseBB);
+    IRBCase.CreateBr(MergeBB);
+    SI->addCase(CaseSizeId, CaseBB);
+    DEBUG(dbgs() << *CaseBB << "\n");
+  }
+  setProfMetadata(Func.getParent(), SI, CaseCounts, MaxCount);
+
+  DEBUG(dbgs() << *BB << "\n");
+  DEBUG(dbgs() << *DefaultBB << "\n");
+  DEBUG(dbgs() << *MergeBB << "\n");
+
+  ORE.emit([&]() {
+    using namespace ore;
+    return OptimizationRemark(DEBUG_TYPE, "memopt-opt", MI)
+             << "optimized " << NV("Intrinsic", StringRef(getMIName(MI)))
+             << " with count " << NV("Count", SumForOpt) << " out of "
+             << NV("Total", TotalCount) << " for " << NV("Versions", Version)
+             << " versions";
+  });
+
+  return true;
+}
+} // namespace
+
+static bool PGOMemOPSizeOptImpl(Function &F, BlockFrequencyInfo &BFI,
+                                OptimizationRemarkEmitter &ORE) {
+  if (DisableMemOPOPT)
+    return false;
+
+  if (F.hasFnAttribute(Attribute::OptimizeForSize))
+    return false;
+  MemOPSizeOpt MemOPSizeOpt(F, BFI, ORE);
+  MemOPSizeOpt.perform();
+  return MemOPSizeOpt.isChanged();
+}
+
+bool PGOMemOPSizeOptLegacyPass::runOnFunction(Function &F) {
+  BlockFrequencyInfo &BFI =
+      getAnalysis<BlockFrequencyInfoWrapperPass>().getBFI();
+  auto &ORE = getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE();
+  return PGOMemOPSizeOptImpl(F, BFI, ORE);
+}
+
+namespace llvm {
+char &PGOMemOPSizeOptID = PGOMemOPSizeOptLegacyPass::ID;
+
+PreservedAnalyses PGOMemOPSizeOpt::run(Function &F,
+                                       FunctionAnalysisManager &FAM) {
+  auto &BFI = FAM.getResult<BlockFrequencyAnalysis>(F);
+  auto &ORE = FAM.getResult<OptimizationRemarkEmitterAnalysis>(F);
+  bool Changed = PGOMemOPSizeOptImpl(F, BFI, ORE);
+  if (!Changed)
+    return PreservedAnalyses::all();
+  auto PA = PreservedAnalyses();
+  PA.preserve<GlobalsAA>();
+  return PA;
+}
+} // namespace llvm