CodeGenPGO.h source code [clang_source_code/lib/CodeGen/CodeGenPGO.h]

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
23	namespace clang {
24	namespace CodeGen {
25
26	/// Per-function PGO state.
27	class CodeGenPGO {
28	private:
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
42	public:
43	CodeGenPGO(CodeGenModule &CGM)
44	: CGM(CGM), NumValueSites({{0}}), NumRegionCounters(0), FunctionHash(0),
45	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) {
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);
90	private:
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
102	public:
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