clang  8.0.0svn
CodeGenPGO.h
Go to the documentation of this file.
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 "llvm/ProfileData/InstrProfReader.h"
21 #include <array>
22 #include <memory>
23 
24 namespace clang {
25 namespace CodeGen {
26 
27 /// Per-function PGO state.
28 class CodeGenPGO {
29 private:
30  CodeGenModule &CGM;
31  std::string FuncName;
32  llvm::GlobalVariable *FuncNameVar;
33 
34  std::array <unsigned, llvm::IPVK_Last + 1> NumValueSites;
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::unique_ptr<llvm::InstrProfRecord> ProfRecord;
40  std::vector<uint64_t> RegionCounts;
41  uint64_t CurrentRegionCount;
42 
43 public:
45  : CGM(CGM), NumValueSites({{0}}), NumRegionCounters(0), FunctionHash(0),
46  CurrentRegionCount(0) {}
47 
48  /// Whether or not we have PGO region data for the current function. This is
49  /// false both when we have no data at all and when our data has been
50  /// discarded.
51  bool haveRegionCounts() const { return !RegionCounts.empty(); }
52 
53  /// Return the counter value of the current region.
54  uint64_t getCurrentRegionCount() const { return CurrentRegionCount; }
55 
56  /// Set the counter value for the current region. This is used to keep track
57  /// of changes to the most recent counter from control flow and non-local
58  /// exits.
59  void setCurrentRegionCount(uint64_t Count) { CurrentRegionCount = Count; }
60 
61  /// Check if an execution count is known for a given statement. If so, return
62  /// true and put the value in Count; else return false.
64  if (!StmtCountMap)
65  return None;
66  auto I = StmtCountMap->find(S);
67  if (I == StmtCountMap->end())
68  return None;
69  return I->second;
70  }
71 
72  /// If the execution count for the current statement is known, record that
73  /// as the current count.
74  void setCurrentStmt(const Stmt *S) {
75  if (auto Count = getStmtCount(S))
76  setCurrentRegionCount(*Count);
77  }
78 
79  /// Assign counters to regions and configure them for PGO of a given
80  /// function. Does nothing if instrumentation is not enabled and either
81  /// generates global variables or associates PGO data with each of the
82  /// counters depending on whether we are generating or using instrumentation.
83  void assignRegionCounters(GlobalDecl GD, llvm::Function *Fn);
84  /// Emit a coverage mapping range with a counter zero
85  /// for an unused declaration.
86  void emitEmptyCounterMapping(const Decl *D, StringRef FuncName,
87  llvm::GlobalValue::LinkageTypes Linkage);
88  // Insert instrumentation or attach profile metadata at value sites
89  void valueProfile(CGBuilderTy &Builder, uint32_t ValueKind,
90  llvm::Instruction *ValueSite, llvm::Value *ValuePtr);
91 private:
92  void setFuncName(llvm::Function *Fn);
93  void setFuncName(StringRef Name, llvm::GlobalValue::LinkageTypes Linkage);
94  void mapRegionCounters(const Decl *D);
95  void computeRegionCounts(const Decl *D);
96  void applyFunctionAttributes(llvm::IndexedInstrProfReader *PGOReader,
97  llvm::Function *Fn);
98  void loadRegionCounts(llvm::IndexedInstrProfReader *PGOReader,
99  bool IsInMainFile);
100  bool skipRegionMappingForDecl(const Decl *D);
101  void emitCounterRegionMapping(const Decl *D);
102 
103 public:
104  void emitCounterIncrement(CGBuilderTy &Builder, const Stmt *S,
105  llvm::Value *StepV);
106 
107  /// Return the region count for the counter at the given index.
108  uint64_t getRegionCount(const Stmt *S) {
109  if (!RegionCounterMap)
110  return 0;
111  if (!haveRegionCounts())
112  return 0;
113  return RegionCounts[(*RegionCounterMap)[S]];
114  }
115 };
116 
117 } // end namespace CodeGen
118 } // end namespace clang
119 
120 #endif
Optional< uint64_t > getStmtCount(const Stmt *S)
Check if an execution count is known for a given statement.
Definition: CodeGenPGO.h:63
Stmt - This represents one statement.
Definition: Stmt.h:66
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:87
void emitCounterIncrement(CGBuilderTy &Builder, const Stmt *S, llvm::Value *StepV)
Definition: CodeGenPGO.cpp:888
Linkage
Describes the different kinds of linkage (C++ [basic.link], C99 6.2.2) that an entity may have...
Definition: Linkage.h:24
void setCurrentRegionCount(uint64_t Count)
Set the counter value for the current region.
Definition: CodeGenPGO.h:59
void assignRegionCounters(GlobalDecl GD, llvm::Function *Fn)
Assign counters to regions and configure them for PGO of a given function.
Definition: CodeGenPGO.cpp:755
void valueProfile(CGBuilderTy &Builder, uint32_t ValueKind, llvm::Instruction *ValueSite, llvm::Value *ValuePtr)
Definition: CodeGenPGO.cpp:913
GlobalDecl - represents a global declaration.
Definition: GlobalDecl.h:35
Per-function PGO state.
Definition: CodeGenPGO.h:28
uint64_t getCurrentRegionCount() const
Return the counter value of the current region.
Definition: CodeGenPGO.h:54
This class organizes the cross-function state that is used while generating LLVM code.
Dataflow Directional Tag Classes.
void emitEmptyCounterMapping(const Decl *D, StringRef FuncName, llvm::GlobalValue::LinkageTypes Linkage)
Emit a coverage mapping range with a counter zero for an unused declaration.
Definition: CodeGenPGO.cpp:844
void setCurrentStmt(const Stmt *S)
If the execution count for the current statement is known, record that as the current count...
Definition: CodeGenPGO.h:74
uint64_t getRegionCount(const Stmt *S)
Return the region count for the counter at the given index.
Definition: CodeGenPGO.h:108
bool haveRegionCounts() const
Whether or not we have PGO region data for the current function.
Definition: CodeGenPGO.h:51
CodeGenPGO(CodeGenModule &CGM)
Definition: CodeGenPGO.h:44