Profile.h revision 353358 
1//===- Profile.h - XRay Profile Abstraction -------------------------------===//
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// Defines the XRay Profile class representing the latency profile generated by
10// XRay's profiling mode.
11//
12//===----------------------------------------------------------------------===//
13#ifndef LLVM_XRAY_PROFILE_H
14#define LLVM_XRAY_PROFILE_H
15
16#include "llvm/ADT/DenseMap.h"
17#include "llvm/ADT/SmallVector.h"
18#include "llvm/ADT/StringRef.h"
19#include "llvm/Support/Error.h"
20#include <list>
21#include <utility>
22#include <vector>
23
24namespace llvm {
25namespace xray {
26
27class Profile;
28
29// We forward declare the Trace type for turning a Trace into a Profile.
30class Trace;
31
32/// This function will attempt to load an XRay Profiling Mode profile from the
33/// provided |Filename|.
34///
35/// For any errors encountered in the loading of the profile data from
36/// |Filename|, this function will return an Error condition appropriately.
37Expected<Profile> loadProfile(StringRef Filename);
38
39/// This algorithm will merge two Profile instances into a single Profile
40/// instance, aggregating blocks by Thread ID.
41Profile mergeProfilesByThread(const Profile &L, const Profile &R);
42
43/// This algorithm will merge two Profile instances into a single Profile
44/// instance, aggregating blocks by function call stack.
45Profile mergeProfilesByStack(const Profile &L, const Profile &R);
46
47/// This function takes a Trace and creates a Profile instance from it.
48Expected<Profile> profileFromTrace(const Trace &T);
49
50/// Profile instances are thread-compatible.
51class Profile {
52public:
53  using ThreadID = uint64_t;
54  using PathID = unsigned;
55  using FuncID = int32_t;
56
57  struct Data {
58    uint64_t CallCount;
59    uint64_t CumulativeLocalTime;
60  };
61
62  struct Block {
63    ThreadID Thread;
64    std::vector<std::pair<PathID, Data>> PathData;
65  };
66
67  /// Provides a sequence of function IDs from a previously interned PathID.
68  ///
69  /// Returns an error if |P| had not been interned before into the Profile.
70  ///
71  Expected<std::vector<FuncID>> expandPath(PathID P) const;
72
73  /// The stack represented in |P| must be in stack order (leaf to root). This
74  /// will always return the same PathID for |P| that has the same sequence.
75  PathID internPath(ArrayRef<FuncID> P);
76
77  /// Appends a fully-formed Block instance into the Profile.
78  ///
79  /// Returns an error condition in the following cases:
80  ///
81  ///    - The PathData component of the Block is empty
82  ///
83  Error addBlock(Block &&B);
84
85  Profile() = default;
86  ~Profile() = default;
87
88  Profile(Profile &&O) noexcept
89      : Blocks(std::move(O.Blocks)), NodeStorage(std::move(O.NodeStorage)),
90        Roots(std::move(O.Roots)), PathIDMap(std::move(O.PathIDMap)),
91        NextID(O.NextID) {}
92
93  Profile &operator=(Profile &&O) noexcept {
94    Blocks = std::move(O.Blocks);
95    NodeStorage = std::move(O.NodeStorage);
96    Roots = std::move(O.Roots);
97    PathIDMap = std::move(O.PathIDMap);
98    NextID = O.NextID;
99    return *this;
100  }
101
102  Profile(const Profile &);
103  Profile &operator=(const Profile &);
104
105  friend void swap(Profile &L, Profile &R) {
106    using std::swap;
107    swap(L.Blocks, R.Blocks);
108    swap(L.NodeStorage, R.NodeStorage);
109    swap(L.Roots, R.Roots);
110    swap(L.PathIDMap, R.PathIDMap);
111    swap(L.NextID, R.NextID);
112  }
113
114private:
115  using BlockList = std::list<Block>;
116
117  struct TrieNode {
118    FuncID Func = 0;
119    std::vector<TrieNode *> Callees{};
120    TrieNode *Caller = nullptr;
121    PathID ID = 0;
122  };
123
124  // List of blocks associated with a Profile.
125  BlockList Blocks;
126
127  // List of TrieNode elements we've seen.
128  std::list<TrieNode> NodeStorage;
129
130  // List of call stack roots.
131  SmallVector<TrieNode *, 4> Roots;
132
133  // Reverse mapping between a PathID to a TrieNode*.
134  DenseMap<PathID, TrieNode *> PathIDMap;
135
136  // Used to identify paths.
137  PathID NextID = 1;
138
139public:
140  using const_iterator = BlockList::const_iterator;
141  const_iterator begin() const { return Blocks.begin(); }
142  const_iterator end() const { return Blocks.end(); }
143  bool empty() const { return Blocks.empty(); }
144};
145
146} // namespace xray
147} // namespace llvm
148
149#endif
150