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//===- BlockFrequencyInfo.h - Block Frequency Analysis ----------*- 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

//

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

//

// Loops should be simplified before this analysis.

//

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

#ifndef LLVM_ANALYSIS_BLOCKFREQUENCYINFO_H

#define LLVM_ANALYSIS_BLOCKFREQUENCYINFO_H

#include "llvm/IR/PassManager.h"

#include "llvm/Pass.h"

#include "llvm/Support/BlockFrequency.h"

#include <cstdint>

#include <memory>

#include <optional>

namespace llvm {

class BasicBlock;

class BranchProbabilityInfo;

class Function;

class LoopInfo;

class Module;

class raw_ostream;

template <class BlockT> class BlockFrequencyInfoImpl;

enum PGOViewCountsType { PGOVCT_None, PGOVCT_Graph, PGOVCT_Text };

/// BlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation to

/// estimate IR basic block frequencies.

class BlockFrequencyInfo {

  using ImplType = BlockFrequencyInfoImpl<BasicBlock>;

  std::unique_ptr<ImplType> BFI;

public:

  BlockFrequencyInfo();

  BlockFrequencyInfo(const Function &F, const BranchProbabilityInfo &BPI,

                     const LoopInfo &LI);

  BlockFrequencyInfo(const BlockFrequencyInfo &) = delete;

  BlockFrequencyInfo &operator=(const BlockFrequencyInfo &) = delete;

  BlockFrequencyInfo(BlockFrequencyInfo &&Arg);

  BlockFrequencyInfo &operator=(BlockFrequencyInfo &&RHS);

  ~BlockFrequencyInfo();

  /// Handle invalidation explicitly.

  bool invalidate(Function &F, const PreservedAnalyses &PA,

                  FunctionAnalysisManager::Invalidator &);

  const Function *getFunction() const;

  const BranchProbabilityInfo *getBPI() const;

  void view(StringRef = "BlockFrequencyDAGs") const;

  /// getblockFreq - Return block frequency. Return 0 if we don't have the

  /// information. Please note that initial frequency is equal to ENTRY_FREQ. It

  /// means that we should not rely on the value itself, but only on the

  /// comparison to the other block frequencies. We do this to avoid using of

  /// floating points.

  BlockFrequency getBlockFreq(const BasicBlock *BB) const;

  /// Returns the estimated profile count of \p BB.

  /// This computes the relative block frequency of \p BB and multiplies it by

  /// the enclosing function's count (if available) and returns the value.

  std::optional<uint64_t>

  getBlockProfileCount(const BasicBlock *BB, bool AllowSynthetic = false) const;

  /// Returns the estimated profile count of \p Freq.

  /// This uses the frequency \p Freq and multiplies it by

  /// the enclosing function's count (if available) and returns the value.

  std::optional<uint64_t> getProfileCountFromFreq(uint64_t Freq) const;

  /// Returns true if \p BB is an irreducible loop header

  /// block. Otherwise false.

  bool isIrrLoopHeader(const BasicBlock *BB);

  // Set the frequency of the given basic block.

  void setBlockFreq(const BasicBlock *BB, uint64_t Freq);

  /// Set the frequency of \p ReferenceBB to \p Freq and scale the frequencies

  /// of the blocks in \p BlocksToScale such that their frequencies relative

  /// to \p ReferenceBB remain unchanged.

  void setBlockFreqAndScale(const BasicBlock *ReferenceBB, uint64_t Freq,

                            SmallPtrSetImpl<BasicBlock *> &BlocksToScale);

  /// calculate - compute block frequency info for the given function.

  void calculate(const Function &F, const BranchProbabilityInfo &BPI,

                 const LoopInfo &LI);

  // Print the block frequency Freq to OS using the current functions entry

  // frequency to convert freq into a relative decimal form.

  raw_ostream &printBlockFreq(raw_ostream &OS, const BlockFrequency Freq) const;

  // Convenience method that attempts to look up the frequency associated with

  // BB and print it to OS.

  raw_ostream &printBlockFreq(raw_ostream &OS, const BasicBlock *BB) const;

  uint64_t getEntryFreq() const;

  void releaseMemory();

  void print(raw_ostream &OS) const;

  // Compare to the other BFI and verify they match.

  void verifyMatch(BlockFrequencyInfo &Other) const;

};

/// Analysis pass which computes \c BlockFrequencyInfo.

class BlockFrequencyAnalysis

    : public AnalysisInfoMixin<BlockFrequencyAnalysis> {

  friend AnalysisInfoMixin<BlockFrequencyAnalysis>;

  static AnalysisKey Key;

public:

  /// Provide the result type for this analysis pass.

  using Result = BlockFrequencyInfo;

  /// Run the analysis pass over a function and produce BFI.

  Result run(Function &F, FunctionAnalysisManager &AM);

};

/// Printer pass for the \c BlockFrequencyInfo results.

class BlockFrequencyPrinterPass

    : public PassInfoMixin<BlockFrequencyPrinterPass> {

  raw_ostream &OS;

public:

  explicit BlockFrequencyPrinterPass(raw_ostream &OS) : OS(OS) {}

  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);

};

/// Legacy analysis pass which computes \c BlockFrequencyInfo.

class BlockFrequencyInfoWrapperPass : public FunctionPass {

  BlockFrequencyInfo BFI;

public:

  static char ID;

  BlockFrequencyInfoWrapperPass();

  ~BlockFrequencyInfoWrapperPass() override;

  BlockFrequencyInfo &getBFI() { return BFI; }

  const BlockFrequencyInfo &getBFI() const { return BFI; }

  void getAnalysisUsage(AnalysisUsage &AU) const override;

  bool runOnFunction(Function &F) override;

  void releaseMemory() override;

  void print(raw_ostream &OS, const Module *M) const override;

};

} // end namespace llvm

#endif // LLVM_ANALYSIS_BLOCKFREQUENCYINFO_H