1//===--- CodeGenPGO.h - PGO Instrumentation for LLVM CodeGen ----*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Instrumentation-based profile-guided optimization
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H
15#define LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H
16
17#include "CGBuilder.h"
18#include "CodeGenModule.h"
19#include "CodeGenTypes.h"
20#include "clang/Frontend/CodeGenOptions.h"
21#include "llvm/ADT/StringMap.h"
22#include "llvm/Support/MemoryBuffer.h"
23#include <memory>
24
25namespace clang {
26namespace CodeGen {
27
28/// Per-function PGO state.
29class CodeGenPGO {
30private:
31  CodeGenModule &CGM;
32  std::string FuncName;
33  llvm::GlobalVariable *FuncNameVar;
34
35  unsigned NumRegionCounters;
36  uint64_t FunctionHash;
37  std::unique_ptr<llvm::DenseMap<const Stmt *, unsigned>> RegionCounterMap;
38  std::unique_ptr<llvm::DenseMap<const Stmt *, uint64_t>> StmtCountMap;
39  std::vector<uint64_t> RegionCounts;
40  uint64_t CurrentRegionCount;
41  /// \brief A flag that is set to true when this function doesn't need
42  /// to have coverage mapping data.
43  bool SkipCoverageMapping;
44
45public:
46  CodeGenPGO(CodeGenModule &CGM)
47      : CGM(CGM), NumRegionCounters(0), FunctionHash(0), CurrentRegionCount(0),
48        SkipCoverageMapping(false) {}
49
50  /// Whether or not we have PGO region data for the current function. This is
51  /// false both when we have no data at all and when our data has been
52  /// discarded.
53  bool haveRegionCounts() const { return !RegionCounts.empty(); }
54
55  /// Return the counter value of the current region.
56  uint64_t getCurrentRegionCount() const { return CurrentRegionCount; }
57
58  /// Set the counter value for the current region. This is used to keep track
59  /// of changes to the most recent counter from control flow and non-local
60  /// exits.
61  void setCurrentRegionCount(uint64_t Count) { CurrentRegionCount = Count; }
62
63  /// Check if an execution count is known for a given statement. If so, return
64  /// true and put the value in Count; else return false.
65  Optional<uint64_t> getStmtCount(const Stmt *S) {
66    if (!StmtCountMap)
67      return None;
68    auto I = StmtCountMap->find(S);
69    if (I == StmtCountMap->end())
70      return None;
71    return I->second;
72  }
73
74  /// If the execution count for the current statement is known, record that
75  /// as the current count.
76  void setCurrentStmt(const Stmt *S) {
77    if (auto Count = getStmtCount(S))
78      setCurrentRegionCount(*Count);
79  }
80
81  /// Assign counters to regions and configure them for PGO of a given
82  /// function. Does nothing if instrumentation is not enabled and either
83  /// generates global variables or associates PGO data with each of the
84  /// counters depending on whether we are generating or using instrumentation.
85  void assignRegionCounters(GlobalDecl GD, llvm::Function *Fn);
86  /// Emit a coverage mapping range with a counter zero
87  /// for an unused declaration.
88  void emitEmptyCounterMapping(const Decl *D, StringRef FuncName,
89                               llvm::GlobalValue::LinkageTypes Linkage);
90private:
91  void setFuncName(llvm::Function *Fn);
92  void setFuncName(StringRef Name, llvm::GlobalValue::LinkageTypes Linkage);
93  void mapRegionCounters(const Decl *D);
94  void computeRegionCounts(const Decl *D);
95  void applyFunctionAttributes(llvm::IndexedInstrProfReader *PGOReader,
96                               llvm::Function *Fn);
97  void loadRegionCounts(llvm::IndexedInstrProfReader *PGOReader,
98                        bool IsInMainFile);
99  void emitCounterRegionMapping(const Decl *D);
100
101public:
102  void emitCounterIncrement(CGBuilderTy &Builder, const Stmt *S);
103
104  /// Return the region count for the counter at the given index.
105  uint64_t getRegionCount(const Stmt *S) {
106    if (!RegionCounterMap)
107      return 0;
108    if (!haveRegionCounts())
109      return 0;
110    return RegionCounts[(*RegionCounterMap)[S]];
111  }
112};
113
114}  // end namespace CodeGen
115}  // end namespace clang
116
117#endif
118