//===--- CodeGenPGO.h - PGO Instrumentation for LLVM CodeGen ----*- C++ -*-===//

//

// 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

//

//===----------------------------------------------------------------------===//

//

// Instrumentation-based profile-guided optimization

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H

#define LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H

#include "CGBuilder.h"

#include "CodeGenModule.h"

#include "CodeGenTypes.h"

#include "llvm/ProfileData/InstrProfReader.h"

#include <array>

#include <memory>

namespace clang {

namespace CodeGen {

/// Per-function PGO state.

class CodeGenPGO {

private:

  CodeGenModule &CGM;

  std::string FuncName;

  llvm::GlobalVariable *FuncNameVar;

  std::array <unsigned, llvm::IPVK_Last + 1> NumValueSites;

  unsigned NumRegionCounters;

  uint64_t FunctionHash;

  std::unique_ptr<llvm::DenseMap<const Stmt *, unsigned>> RegionCounterMap;

  std::unique_ptr<llvm::DenseMap<const Stmt *, uint64_t>> StmtCountMap;

  std::unique_ptr<llvm::InstrProfRecord> ProfRecord;

  std::vector<uint64_t> RegionCounts;

  uint64_t CurrentRegionCount;

public:

  CodeGenPGO(CodeGenModule &CGModule)

      : CGM(CGModule), FuncNameVar(nullptr), NumValueSites({{0}}),

        NumRegionCounters(0), FunctionHash(0), CurrentRegionCount(0) {}

  /// Whether or not we have PGO region data for the current function. This is

  /// false both when we have no data at all and when our data has been

  /// discarded.

  bool haveRegionCounts() const { return !RegionCounts.empty(); }

  /// Return the counter value of the current region.

  uint64_t getCurrentRegionCount() const { return CurrentRegionCount; }

  /// Set the counter value for the current region. This is used to keep track

  /// of changes to the most recent counter from control flow and non-local

  /// exits.

  void setCurrentRegionCount(uint64_t Count) { CurrentRegionCount = Count; }

  /// Check if an execution count is known for a given statement. If so, return

  /// true and put the value in Count; else return false.

  Optional<uint64_t> getStmtCount(const Stmt *S) const {

    if (!StmtCountMap)

      return None;

    auto I = StmtCountMap->find(S);

    if (I == StmtCountMap->end())

      return None;

    return I->second;

  }

  /// If the execution count for the current statement is known, record that

  /// as the current count.

  void setCurrentStmt(const Stmt *S) {

    if (auto Count = getStmtCount(S))

      setCurrentRegionCount(*Count);

  }

  /// Assign counters to regions and configure them for PGO of a given

  /// function. Does nothing if instrumentation is not enabled and either

  /// generates global variables or associates PGO data with each of the

  /// counters depending on whether we are generating or using instrumentation.

  void assignRegionCounters(GlobalDecl GD, llvm::Function *Fn);

  /// Emit a coverage mapping range with a counter zero

  /// for an unused declaration.

  void emitEmptyCounterMapping(const Decl *D, StringRef FuncName,

                               llvm::GlobalValue::LinkageTypes Linkage);

  // Insert instrumentation or attach profile metadata at value sites

  void valueProfile(CGBuilderTy &Builder, uint32_t ValueKind,

                    llvm::Instruction *ValueSite, llvm::Value *ValuePtr);

  // Set a module flag indicating if value profiling is enabled.

  void setValueProfilingFlag(llvm::Module &M);

private:

  void setFuncName(llvm::Function *Fn);

  void setFuncName(StringRef Name, llvm::GlobalValue::LinkageTypes Linkage);

  void mapRegionCounters(const Decl *D);

  void computeRegionCounts(const Decl *D);

  void applyFunctionAttributes(llvm::IndexedInstrProfReader *PGOReader,

                               llvm::Function *Fn);

  void loadRegionCounts(llvm::IndexedInstrProfReader *PGOReader,

                        bool IsInMainFile);

  bool skipRegionMappingForDecl(const Decl *D);

  void emitCounterRegionMapping(const Decl *D);

public:

  void emitCounterIncrement(CGBuilderTy &Builder, const Stmt *S,

                            llvm::Value *StepV);

  /// Return the region count for the counter at the given index.

  uint64_t getRegionCount(const Stmt *S) {

    if (!RegionCounterMap)

      return 0;

    if (!haveRegionCounts())

      return 0;

    return RegionCounts[(*RegionCounterMap)[S]];

  }

};

}  // end namespace CodeGen

}  // end namespace clang

#endif