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//===- MachineBlockFrequencyInfo.h - MBB Frequency Analysis -----*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// Loops should be simplified before this analysis.
#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;
static char ID;
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 {
assert(getEntryFreq() != 0 && "getEntryFreq() should not return 0 here!");
return getBlockFreq(MBB).getFrequency() * (1.0f / getEntryFreq());
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