1//===-- ImportedFunctionsInliningStatistics.h -------------------*- 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// Generating inliner statistics for imported functions, mostly useful for
9// ThinLTO.
10//===----------------------------------------------------------------------===//
11
12#ifndef LLVM_TRANSFORMS_UTILS_IMPORTEDFUNCTIONSINLININGSTATISTICS_H
13#define LLVM_TRANSFORMS_UTILS_IMPORTEDFUNCTIONSINLININGSTATISTICS_H
14
15#include "llvm/ADT/SmallVector.h"
16#include "llvm/ADT/StringMap.h"
17#include "llvm/ADT/StringRef.h"
18#include <string>
19#include <vector>
20
21namespace llvm {
22class Module;
23class Function;
24/// Calculate and dump ThinLTO specific inliner stats.
25/// The main statistics are:
26/// (1) Number of inlined imported functions,
27/// (2) Number of imported functions inlined into importing module (indirect),
28/// (3) Number of non imported functions inlined into importing module
29/// (indirect).
30/// The difference between first and the second is that first stat counts
31/// all performed inlines on imported functions, but the second one only the
32/// functions that have been eventually inlined to a function in the importing
33/// module (by a chain of inlines). Because llvm uses bottom-up inliner, it is
34/// possible to e.g. import function `A`, `B` and then inline `B` to `A`,
35/// and after this `A` might be too big to be inlined into some other function
36/// that calls it. It calculates this statistic by building graph, where
37/// the nodes are functions, and edges are performed inlines and then by marking
38/// the edges starting from not imported function.
39///
40/// If `Verbose` is set to true, then it also dumps statistics
41/// per each inlined function, sorted by the greatest inlines count like
42/// - number of performed inlines
43/// - number of performed inlines to importing module
44class ImportedFunctionsInliningStatistics {
45private:
46  /// InlineGraphNode represents node in graph of inlined functions.
47  struct InlineGraphNode {
48    // Default-constructible and movable.
49    InlineGraphNode() = default;
50    InlineGraphNode(InlineGraphNode &&) = default;
51    InlineGraphNode &operator=(InlineGraphNode &&) = default;
52
53    llvm::SmallVector<InlineGraphNode *, 8> InlinedCallees;
54    /// Incremented every direct inline.
55    int32_t NumberOfInlines = 0;
56    /// Number of inlines into non imported function (possibly indirect via
57    /// intermediate inlines). Computed based on graph search.
58    int32_t NumberOfRealInlines = 0;
59    bool Imported = false;
60    bool Visited = false;
61  };
62
63public:
64  ImportedFunctionsInliningStatistics() = default;
65  ImportedFunctionsInliningStatistics(
66      const ImportedFunctionsInliningStatistics &) = delete;
67
68  /// Set information like AllFunctions, ImportedFunctions, ModuleName.
69  void setModuleInfo(const Module &M);
70  /// Record inline of @param Callee to @param Caller for statistis.
71  void recordInline(const Function &Caller, const Function &Callee);
72  /// Dump stats computed with InlinerStatistics class.
73  /// If @param Verbose is true then separate statistics for every inlined
74  /// function will be printed.
75  void dump(bool Verbose);
76
77private:
78  /// Creates new Node in NodeMap and sets attributes, or returns existed one.
79  InlineGraphNode &createInlineGraphNode(const Function &);
80  void calculateRealInlines();
81  void dfs(InlineGraphNode &GraphNode);
82
83  using NodesMapTy =
84      llvm::StringMap<std::unique_ptr<InlineGraphNode>>;
85  using SortedNodesTy =
86      std::vector<const NodesMapTy::MapEntryTy*>;
87  /// Returns vector of elements sorted by
88  /// (-NumberOfInlines, -NumberOfRealInlines, FunctionName).
89  SortedNodesTy getSortedNodes();
90
91private:
92  /// This map manage life of all InlineGraphNodes. Unique pointer to
93  /// InlineGraphNode used since the node pointers are also saved in the
94  /// InlinedCallees vector. If it would store InlineGraphNode instead then the
95  /// address of the node would not be invariant.
96  NodesMapTy NodesMap;
97  /// Non external functions that have some other function inlined inside.
98  std::vector<StringRef> NonImportedCallers;
99  int AllFunctions = 0;
100  int ImportedFunctions = 0;
101  StringRef ModuleName;
102};
103
104} // llvm
105
106#endif // LLVM_TRANSFORMS_UTILS_IMPORTEDFUNCTIONSINLININGSTATISTICS_H
107