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  1. //===- CodeLayout.h - Code layout/placement algorithms  ---------*- C++ -*-===//
  2. //
  3. // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  4. // See https://llvm.org/LICENSE.txt for license information.
  5. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  6. //
  7. //===----------------------------------------------------------------------===//
  8. //
  9. /// \file
  10. /// Declares methods and data structures for code layout algorithms.
  11. //
  12. //===----------------------------------------------------------------------===//
  13.  
  14. #ifndef LLVM_TRANSFORMS_UTILS_CODELAYOUT_H
  15. #define LLVM_TRANSFORMS_UTILS_CODELAYOUT_H
  16.  
  17. #include "llvm/ADT/DenseMap.h"
  18.  
  19. #include <vector>
  20.  
  21. namespace llvm {
  22.  
  23. using EdgeT = std::pair<uint64_t, uint64_t>;
  24. using EdgeCountT = std::pair<EdgeT, uint64_t>;
  25.  
  26. /// Find a layout of nodes (basic blocks) of a given CFG optimizing jump
  27. /// locality and thus processor I-cache utilization. This is achieved via
  28. /// increasing the number of fall-through jumps and co-locating frequently
  29. /// executed nodes together.
  30. /// The nodes are assumed to be indexed by integers from [0, |V|) so that the
  31. /// current order is the identity permutation.
  32. /// \p NodeSizes: The sizes of the nodes (in bytes).
  33. /// \p NodeCounts: The execution counts of the nodes in the profile.
  34. /// \p EdgeCounts: The execution counts of every edge (jump) in the profile. The
  35. ///    map also defines the edges in CFG and should include 0-count edges.
  36. /// \returns The best block order found.
  37. std::vector<uint64_t>
  38. applyExtTspLayout(const std::vector<uint64_t> &NodeSizes,
  39.                   const std::vector<uint64_t> &NodeCounts,
  40.                   const std::vector<EdgeCountT> &EdgeCounts);
  41.  
  42. /// Estimate the "quality" of a given node order in CFG. The higher the score,
  43. /// the better the order is. The score is designed to reflect the locality of
  44. /// the given order, which is anti-correlated with the number of I-cache misses
  45. /// in a typical execution of the function.
  46. double calcExtTspScore(const std::vector<uint64_t> &Order,
  47.                        const std::vector<uint64_t> &NodeSizes,
  48.                        const std::vector<uint64_t> &NodeCounts,
  49.                        const std::vector<EdgeCountT> &EdgeCounts);
  50.  
  51. /// Estimate the "quality" of the current node order in CFG.
  52. double calcExtTspScore(const std::vector<uint64_t> &NodeSizes,
  53.                        const std::vector<uint64_t> &NodeCounts,
  54.                        const std::vector<EdgeCountT> &EdgeCounts);
  55.  
  56. } // end namespace llvm
  57.  
  58. #endif // LLVM_TRANSFORMS_UTILS_CODELAYOUT_H
  59.