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 "MCDCState.h"
20#include "llvm/ProfileData/InstrProfReader.h"
21#include <array>
22#include <memory>
23#include <optional>
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 std::array <unsigned, llvm::IPVK_Last + 1> NumValueSites;
36 unsigned NumRegionCounters;
37 uint64_t FunctionHash;
38 std::unique_ptr<llvm::DenseMap<const Stmt *, CounterPair>> RegionCounterMap;
39 std::unique_ptr<llvm::DenseMap<const Stmt *, uint64_t>> StmtCountMap;
40 std::unique_ptr<llvm::InstrProfRecord> ProfRecord;
41 std::unique_ptr<MCDC::State> RegionMCDCState;
42 std::vector<uint64_t> RegionCounts;
43 uint64_t CurrentRegionCount;
44
45public:
46 CodeGenPGO(CodeGenModule &CGModule)
47 : CGM(CGModule), FuncNameVar(nullptr), NumValueSites({._M_elems: {0}}),
48 NumRegionCounters(0), FunctionHash(0), CurrentRegionCount(0) {}
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 std::optional<uint64_t> getStmtCount(const Stmt *S) const {
66 if (!StmtCountMap)
67 return std::nullopt;
68 auto I = StmtCountMap->find(Val: S);
69 if (I == StmtCountMap->end())
70 return std::nullopt;
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);
90 // Insert instrumentation or attach profile metadata at value sites
91 void valueProfile(CGBuilderTy &Builder, uint32_t ValueKind,
92 llvm::Instruction *ValueSite, llvm::Value *ValuePtr);
93
94 // Set a module flag indicating if value profiling is enabled.
95 void setValueProfilingFlag(llvm::Module &M);
96
97 void setProfileVersion(llvm::Module &M);
98
99private:
100 void setFuncName(llvm::Function *Fn);
101 void setFuncName(StringRef Name, llvm::GlobalValue::LinkageTypes Linkage);
102 void mapRegionCounters(const Decl *D);
103 void computeRegionCounts(const Decl *D);
104 void applyFunctionAttributes(llvm::IndexedInstrProfReader *PGOReader,
105 llvm::Function *Fn);
106 void loadRegionCounts(llvm::IndexedInstrProfReader *PGOReader,
107 bool IsInMainFile);
108 bool skipRegionMappingForDecl(const Decl *D);
109 void emitCounterRegionMapping(const Decl *D);
110 bool canEmitMCDCCoverage(const CGBuilderTy &Builder);
111
112public:
113 std::pair<bool, bool> getIsCounterPair(const Stmt *S) const;
114 void emitCounterSetOrIncrement(CGBuilderTy &Builder, const Stmt *S,
115 llvm::Value *StepV);
116 void emitMCDCTestVectorBitmapUpdate(CGBuilderTy &Builder, const Expr *S,
117 Address MCDCCondBitmapAddr,
118 CodeGenFunction &CGF);
119 void emitMCDCParameters(CGBuilderTy &Builder);
120 void emitMCDCCondBitmapReset(CGBuilderTy &Builder, const Expr *S,
121 Address MCDCCondBitmapAddr);
122 void emitMCDCCondBitmapUpdate(CGBuilderTy &Builder, const Expr *S,
123 Address MCDCCondBitmapAddr, llvm::Value *Val,
124 CodeGenFunction &CGF);
125
126 void markStmtAsUsed(bool Skipped, const Stmt *S) {
127 // Do nothing.
128 }
129
130 void markStmtMaybeUsed(const Stmt *S) {
131 // Do nothing.
132 }
133
134 void verifyCounterMap() const {
135 // Do nothing.
136 }
137
138 /// Return the region count for the counter at the given index.
139 uint64_t getRegionCount(const Stmt *S) {
140 if (!RegionCounterMap)
141 return 0;
142 if (!haveRegionCounts())
143 return 0;
144 // With profiles from a differing version of clang we can have mismatched
145 // decl counts. Don't crash in such a case.
146 auto Index = (*RegionCounterMap)[S].Executed;
147 if (Index >= RegionCounts.size())
148 return 0;
149 return RegionCounts[Index];
150 }
151};
152
153} // end namespace CodeGen
154} // end namespace clang
155
156#endif
157