Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- MachineBlockFrequencyInfo.h - MBB 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_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H

#define LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H

#include "llvm/CodeGen/MachineFunctionPass.h"

#include "llvm/Support/BlockFrequency.h"

#include <cstdint>

#include <memory>

#include <optional>

namespace llvm {

template <class BlockT> class BlockFrequencyInfoImpl;

class MachineBasicBlock;

class MachineBranchProbabilityInfo;

class MachineFunction;

class MachineLoopInfo;

class raw_ostream;

/// MachineBlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation

/// to estimate machine basic block frequencies.

class MachineBlockFrequencyInfo : public MachineFunctionPass {

  using ImplType = BlockFrequencyInfoImpl<MachineBasicBlock>;

  std::unique_ptr<ImplType> MBFI;

public:

  static char ID;

  MachineBlockFrequencyInfo();

  explicit MachineBlockFrequencyInfo(MachineFunction &F,

                                     MachineBranchProbabilityInfo &MBPI,

                                     MachineLoopInfo &MLI);

  ~MachineBlockFrequencyInfo() override;

  void getAnalysisUsage(AnalysisUsage &AU) const override;

  bool runOnMachineFunction(MachineFunction &F) override;

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

  void calculate(const MachineFunction &F,

                 const MachineBranchProbabilityInfo &MBPI,

                 const MachineLoopInfo &MLI);

  void releaseMemory() override;

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

  /// information. Please note that initial frequency is equal to 1024. 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.

  /// For example, to get the frequency of a block relative to the entry block,

  /// divide the integral value returned by this function (the

  /// BlockFrequency::getFrequency() value) by getEntryFreq().

  BlockFrequency getBlockFreq(const MachineBasicBlock *MBB) const;

  /// Compute the frequency of the block, relative to the entry block.

  /// This API assumes getEntryFreq() is non-zero.

  float getBlockFreqRelativeToEntryBlock(const MachineBasicBlock *MBB) const {

    return getBlockFreq(MBB).getFrequency() * (1.0f / getEntryFreq());

  }

  std::optional<uint64_t>

  getBlockProfileCount(const MachineBasicBlock *MBB) const;

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

  bool isIrrLoopHeader(const MachineBasicBlock *MBB) const;

  /// incrementally calculate block frequencies when we split edges, to avoid

  /// full CFG traversal.

  void onEdgeSplit(const MachineBasicBlock &NewPredecessor,

                   const MachineBasicBlock &NewSuccessor,

                   const MachineBranchProbabilityInfo &MBPI);

  const MachineFunction *getFunction() const;

  const MachineBranchProbabilityInfo *getMBPI() const;

  /// Pop up a ghostview window with the current block frequency propagation

  /// rendered using dot.

  void view(const Twine &Name, bool isSimple = true) const;

  // 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 MachineBasicBlock *MBB) const;

  /// Divide a block's BlockFrequency::getFrequency() value by this value to

  /// obtain the entry block - relative frequency of said block.

  uint64_t getEntryFreq() const;

};

} // end namespace llvm

#endif // LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H