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/ProfileData/InstrProfReader.h"
23#include "llvm/Support/MemoryBuffer.h"
24#include <array>
25#include <memory>
26
27namespace clang {
28namespace CodeGen {
29
30/// Per-function PGO state.
31class CodeGenPGO {
32private:
33  CodeGenModule &CGM;
34  std::string FuncName;
35  llvm::GlobalVariable *FuncNameVar;
36
37  std::array <unsigned, llvm::IPVK_Last + 1> NumValueSites;
38  unsigned NumRegionCounters;
39  uint64_t FunctionHash;
40  std::unique_ptr<llvm::DenseMap<const Stmt *, unsigned>> RegionCounterMap;
41  std::unique_ptr<llvm::DenseMap<const Stmt *, uint64_t>> StmtCountMap;
42  std::unique_ptr<llvm::InstrProfRecord> ProfRecord;
43  std::vector<uint64_t> RegionCounts;
44  uint64_t CurrentRegionCount;
45  /// \brief A flag that is set to true when this function doesn't need
46  /// to have coverage mapping data.
47  bool SkipCoverageMapping;
48
49public:
50  CodeGenPGO(CodeGenModule &CGM)
51      : CGM(CGM), NumValueSites({{0}}), NumRegionCounters(0),
52        FunctionHash(0), CurrentRegionCount(0), SkipCoverageMapping(false) {}
53
54  /// Whether or not we have PGO region data for the current function. This is
55  /// false both when we have no data at all and when our data has been
56  /// discarded.
57  bool haveRegionCounts() const { return !RegionCounts.empty(); }
58
59  /// Return the counter value of the current region.
60  uint64_t getCurrentRegionCount() const { return CurrentRegionCount; }
61
62  /// Set the counter value for the current region. This is used to keep track
63  /// of changes to the most recent counter from control flow and non-local
64  /// exits.
65  void setCurrentRegionCount(uint64_t Count) { CurrentRegionCount = Count; }
66
67  /// Check if an execution count is known for a given statement. If so, return
68  /// true and put the value in Count; else return false.
69  Optional<uint64_t> getStmtCount(const Stmt *S) {
70    if (!StmtCountMap)
71      return None;
72    auto I = StmtCountMap->find(S);
73    if (I == StmtCountMap->end())
74      return None;
75    return I->second;
76  }
77
78  /// If the execution count for the current statement is known, record that
79  /// as the current count.
80  void setCurrentStmt(const Stmt *S) {
81    if (auto Count = getStmtCount(S))
82      setCurrentRegionCount(*Count);
83  }
84
85  /// Assign counters to regions and configure them for PGO of a given
86  /// function. Does nothing if instrumentation is not enabled and either
87  /// generates global variables or associates PGO data with each of the
88  /// counters depending on whether we are generating or using instrumentation.
89  void assignRegionCounters(GlobalDecl GD, llvm::Function *Fn);
90  /// Emit a coverage mapping range with a counter zero
91  /// for an unused declaration.
92  void emitEmptyCounterMapping(const Decl *D, StringRef FuncName,
93                               llvm::GlobalValue::LinkageTypes Linkage);
94  // Insert instrumentation or attach profile metadata at value sites
95  void valueProfile(CGBuilderTy &Builder, uint32_t ValueKind,
96                    llvm::Instruction *ValueSite, llvm::Value *ValuePtr);
97private:
98  void setFuncName(llvm::Function *Fn);
99  void setFuncName(StringRef Name, llvm::GlobalValue::LinkageTypes Linkage);
100  void mapRegionCounters(const Decl *D);
101  void computeRegionCounts(const Decl *D);
102  void applyFunctionAttributes(llvm::IndexedInstrProfReader *PGOReader,
103                               llvm::Function *Fn);
104  void loadRegionCounts(llvm::IndexedInstrProfReader *PGOReader,
105                        bool IsInMainFile);
106  bool skipRegionMappingForDecl(const Decl *D);
107  void emitCounterRegionMapping(const Decl *D);
108
109public:
110  void emitCounterIncrement(CGBuilderTy &Builder, const Stmt *S);
111
112  /// Return the region count for the counter at the given index.
113  uint64_t getRegionCount(const Stmt *S) {
114    if (!RegionCounterMap)
115      return 0;
116    if (!haveRegionCounts())
117      return 0;
118    return RegionCounts[(*RegionCounterMap)[S]];
119  }
120};
121
122}  // end namespace CodeGen
123}  // end namespace clang
124
125#endif
126