1 //===--- CodeGenPGO.h - PGO Instrumentation for LLVM CodeGen ----*- 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 // 9 // Instrumentation-based profile-guided optimization 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H 14 #define LLVM_CLANG_LIB_CODEGEN_CODEGENPGO_H 15 16 #include "CGBuilder.h" 17 #include "CodeGenModule.h" 18 #include "CodeGenTypes.h" 19 #include "llvm/ProfileData/InstrProfReader.h" 20 #include <array> 21 #include <memory> 22 #include <optional> 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: 44 CodeGenPGO(CodeGenModule &CGModule) 45 : CGM(CGModule), FuncNameVar(nullptr), NumValueSites({{0}}), 46 NumRegionCounters(0), FunctionHash(0), 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. 63 std::optional<uint64_t> getStmtCount(const Stmt *S) const { 64 if (!StmtCountMap) 65 return std::nullopt; 66 auto I = StmtCountMap->find(S); 67 if (I == StmtCountMap->end()) 68 return std::nullopt; 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 92 // Set a module flag indicating if value profiling is enabled. 93 void setValueProfilingFlag(llvm::Module &M); 94 95 private: 96 void setFuncName(llvm::Function *Fn); 97 void setFuncName(StringRef Name, llvm::GlobalValue::LinkageTypes Linkage); 98 void mapRegionCounters(const Decl *D); 99 void computeRegionCounts(const Decl *D); 100 void applyFunctionAttributes(llvm::IndexedInstrProfReader *PGOReader, 101 llvm::Function *Fn); 102 void loadRegionCounts(llvm::IndexedInstrProfReader *PGOReader, 103 bool IsInMainFile); 104 bool skipRegionMappingForDecl(const Decl *D); 105 void emitCounterRegionMapping(const Decl *D); 106 107 public: 108 void emitCounterIncrement(CGBuilderTy &Builder, const Stmt *S, 109 llvm::Value *StepV); 110 111 /// Return the region count for the counter at the given index. 112 uint64_t getRegionCount(const Stmt *S) { 113 if (!RegionCounterMap) 114 return 0; 115 if (!haveRegionCounts()) 116 return 0; 117 return RegionCounts[(*RegionCounterMap)[S]]; 118 } 119 }; 120 121 } // end namespace CodeGen 122 } // end namespace clang 123 124 #endif 125