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 | // With profiles from a differing version of clang we can have mismatched |
118 | // decl counts. Don't crash in such a case. |
119 | auto Index = (*RegionCounterMap)[S]; |
120 | if (Index >= RegionCounts.size()) |
121 | return 0; |
122 | return RegionCounts[Index]; |
123 | } |
124 | }; |
125 | |
126 | } // end namespace CodeGen |
127 | } // end namespace clang |
128 | |
129 | #endif |
130 | |