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