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//===- CodeLayout.h - Code layout/placement algorithms  ---------*- 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

//

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

//

/// \file

/// Declares methods and data structures for code layout algorithms.

//

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

#ifndef LLVM_TRANSFORMS_UTILS_CODELAYOUT_H

#define LLVM_TRANSFORMS_UTILS_CODELAYOUT_H

#include "llvm/ADT/DenseMap.h"

#include <vector>

namespace llvm {

using EdgeT = std::pair<uint64_t, uint64_t>;

using EdgeCountT = std::pair<EdgeT, uint64_t>;

/// Find a layout of nodes (basic blocks) of a given CFG optimizing jump

/// locality and thus processor I-cache utilization. This is achieved via

/// increasing the number of fall-through jumps and co-locating frequently

/// executed nodes together.

/// The nodes are assumed to be indexed by integers from [0, |V|) so that the

/// current order is the identity permutation.

/// \p NodeSizes: The sizes of the nodes (in bytes).

/// \p NodeCounts: The execution counts of the nodes in the profile.

/// \p EdgeCounts: The execution counts of every edge (jump) in the profile. The

///    map also defines the edges in CFG and should include 0-count edges.

/// \returns The best block order found.

std::vector<uint64_t>

applyExtTspLayout(const std::vector<uint64_t> &NodeSizes,

                  const std::vector<uint64_t> &NodeCounts,

                  const std::vector<EdgeCountT> &EdgeCounts);

/// Estimate the "quality" of a given node order in CFG. The higher the score,

/// the better the order is. The score is designed to reflect the locality of

/// the given order, which is anti-correlated with the number of I-cache misses

/// in a typical execution of the function.

double calcExtTspScore(const std::vector<uint64_t> &Order,

                       const std::vector<uint64_t> &NodeSizes,

                       const std::vector<uint64_t> &NodeCounts,

                       const std::vector<EdgeCountT> &EdgeCounts);

/// Estimate the "quality" of the current node order in CFG.

double calcExtTspScore(const std::vector<uint64_t> &NodeSizes,

                       const std::vector<uint64_t> &NodeCounts,

                       const std::vector<EdgeCountT> &EdgeCounts);

} // end namespace llvm

#endif // LLVM_TRANSFORMS_UTILS_CODELAYOUT_H