llvm/bolt/include/bolt/Passes/HFSort.h

//===- bolt/Passes/HFSort.h - Cluster functions by hotness ------*- 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
//
//===----------------------------------------------------------------------===//
//
// Implementation of HFSort algorithm for function ordering:
// https://research.fb.com/wp-content/uploads/2017/01/cgo2017-hfsort-final1.pdf
//
// Cluster functions by hotness.  There are three clustering algorithms:
// 1. clusterize
// 2. pettisAndHansen
// 3. randomClusters
//
//===----------------------------------------------------------------------===//

#ifndef BOLT_PASSES_HFSORT_H
#define BOLT_PASSES_HFSORT_H

#include "bolt/Core/CallGraph.h"

#include <string>
#include <vector>

namespace llvm {
namespace bolt {

class Cluster { … };

// Maximum size of a cluster, in bytes.
constexpr uint32_t MaxClusterSize = …;

// Size of a huge page in bytes.
constexpr uint32_t HugePageSize = …;

inline bool compareClustersDensity(const Cluster &C1, const Cluster &C2) { … }

/*
 * Cluster functions in order to minimize call distance.
 */
std::vector<Cluster> clusterize(const CallGraph &Cg);

/*
 * Pettis-Hansen code layout algorithm
 * reference: K. Pettis and R. C. Hansen, "Profile Guided Code Positioning",
 * PLDI '90
 */
std::vector<Cluster> pettisAndHansen(const CallGraph &Cg);

/* Group functions into clusters randomly. */
std::vector<Cluster> randomClusters(const CallGraph &Cg);

} // end namespace bolt
} // end namespace llvm

#endif // BOLT_PASSES_HFSORT_H