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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 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/CodeGen/MachinePassManager.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 {
using ImplType = BlockFrequencyInfoImpl<MachineBasicBlock>;
std::unique_ptr<ImplType> MBFI;
public:
MachineBlockFrequencyInfo(); // Legacy pass manager only.
explicit MachineBlockFrequencyInfo(MachineFunction &F,
MachineBranchProbabilityInfo &MBPI,
MachineLoopInfo &MLI);
MachineBlockFrequencyInfo(MachineBlockFrequencyInfo &&);
~MachineBlockFrequencyInfo();
/// Handle invalidation explicitly.
bool invalidate(MachineFunction &F, const PreservedAnalyses &PA,
MachineFunctionAnalysisManager::Invalidator &);
/// calculate - compute block frequency info for the given function.
void calculate(const MachineFunction &F,
const MachineBranchProbabilityInfo &MBPI,
const MachineLoopInfo &MLI);
void print(raw_ostream &OS);
void releaseMemory();
/// 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.
double getBlockFreqRelativeToEntryBlock(const MachineBasicBlock *MBB) const {
assert(getEntryFreq() != BlockFrequency(0) &&
"getEntryFreq() should not return 0 here!");
return static_cast<double>(getBlockFreq(MBB).getFrequency()) /
static_cast<double>(getEntryFreq().getFrequency());
}
std::optional<uint64_t>
getBlockProfileCount(const MachineBasicBlock *MBB) const;
std::optional<uint64_t> getProfileCountFromFreq(BlockFrequency 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;
/// Divide a block's BlockFrequency::getFrequency() value by this value to
/// obtain the entry block - relative frequency of said block.
BlockFrequency getEntryFreq() const;
};
/// Print the block frequency @p Freq relative to the current functions entry
/// frequency. Returns a Printable object that can be piped via `<<` to a
/// `raw_ostream`.
Printable printBlockFreq(const MachineBlockFrequencyInfo &MBFI,
BlockFrequency Freq);
/// Convenience function equivalent to calling
/// `printBlockFreq(MBFI, MBFI.getBlockFreq(&MBB))`.
Printable printBlockFreq(const MachineBlockFrequencyInfo &MBFI,
const MachineBasicBlock &MBB);
class MachineBlockFrequencyAnalysis
: public AnalysisInfoMixin<MachineBlockFrequencyAnalysis> {
friend AnalysisInfoMixin<MachineBlockFrequencyAnalysis>;
static AnalysisKey Key;
public:
using Result = MachineBlockFrequencyInfo;
Result run(MachineFunction &MF, MachineFunctionAnalysisManager &MFAM);
};
/// Printer pass for the \c MachineBlockFrequencyInfo results.
class MachineBlockFrequencyPrinterPass
: public PassInfoMixin<MachineBlockFrequencyPrinterPass> {
raw_ostream &OS;
public:
explicit MachineBlockFrequencyPrinterPass(raw_ostream &OS) : OS(OS) {}
PreservedAnalyses run(MachineFunction &MF,
MachineFunctionAnalysisManager &MFAM);
static bool isRequired() { return true; }
};
class MachineBlockFrequencyInfoWrapperPass : public MachineFunctionPass {
MachineBlockFrequencyInfo MBFI;
public:
static char ID;
MachineBlockFrequencyInfoWrapperPass();
void getAnalysisUsage(AnalysisUsage &AU) const override;
bool runOnMachineFunction(MachineFunction &F) override;
void releaseMemory() override { MBFI.releaseMemory(); }
MachineBlockFrequencyInfo &getMBFI() { return MBFI; }
const MachineBlockFrequencyInfo &getMBFI() const { return MBFI; }
};
} // end namespace llvm
#endif // LLVM_CODEGEN_MACHINEBLOCKFREQUENCYINFO_H
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