1 //=-- InstrProfWriter.cpp - Instrumented profiling writer -------------------=//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains support for writing profiling data for clang's
11 // instrumentation based PGO and coverage.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/ProfileData/InstrProfWriter.h"
16 #include "llvm/ADT/StringExtras.h"
17 #include "llvm/Support/EndianStream.h"
18 #include "llvm/Support/OnDiskHashTable.h"
23 static support::endianness ValueProfDataEndianness = support::little;
25 class InstrProfRecordTrait {
27 typedef StringRef key_type;
28 typedef StringRef key_type_ref;
30 typedef const InstrProfWriter::ProfilingData *const data_type;
31 typedef const InstrProfWriter::ProfilingData *const data_type_ref;
33 typedef uint64_t hash_value_type;
34 typedef uint64_t offset_type;
36 static hash_value_type ComputeHash(key_type_ref K) {
37 return IndexedInstrProf::ComputeHash(IndexedInstrProf::HashType, K);
40 static std::pair<offset_type, offset_type>
41 EmitKeyDataLength(raw_ostream &Out, key_type_ref K, data_type_ref V) {
42 using namespace llvm::support;
43 endian::Writer<little> LE(Out);
45 offset_type N = K.size();
46 LE.write<offset_type>(N);
49 for (const auto &ProfileData : *V) {
50 const InstrProfRecord &ProfRecord = ProfileData.second;
51 M += sizeof(uint64_t); // The function hash
52 M += sizeof(uint64_t); // The size of the Counts vector
53 M += ProfRecord.Counts.size() * sizeof(uint64_t);
56 M += ValueProfData::getSize(ProfileData.second);
58 LE.write<offset_type>(M);
60 return std::make_pair(N, M);
63 static void EmitKey(raw_ostream &Out, key_type_ref K, offset_type N){
64 Out.write(K.data(), N);
67 static void EmitData(raw_ostream &Out, key_type_ref, data_type_ref V,
69 using namespace llvm::support;
70 endian::Writer<little> LE(Out);
71 for (const auto &ProfileData : *V) {
72 const InstrProfRecord &ProfRecord = ProfileData.second;
74 LE.write<uint64_t>(ProfileData.first); // Function hash
75 LE.write<uint64_t>(ProfRecord.Counts.size());
76 for (uint64_t I : ProfRecord.Counts)
77 LE.write<uint64_t>(I);
80 std::unique_ptr<ValueProfData> VDataPtr =
81 ValueProfData::serializeFrom(ProfileData.second);
82 uint32_t S = VDataPtr->getSize();
83 VDataPtr->swapBytesFromHost(ValueProfDataEndianness);
84 Out.write((const char *)VDataPtr.get(), S);
90 static std::error_code combineInstrProfRecords(InstrProfRecord &Dest,
91 InstrProfRecord &Source,
92 uint64_t &MaxFunctionCount) {
93 // If the number of counters doesn't match we either have bad data
94 // or a hash collision.
95 if (Dest.Counts.size() != Source.Counts.size())
96 return instrprof_error::count_mismatch;
98 for (size_t I = 0, E = Source.Counts.size(); I < E; ++I) {
99 if (Dest.Counts[I] + Source.Counts[I] < Dest.Counts[I])
100 return instrprof_error::counter_overflow;
101 Dest.Counts[I] += Source.Counts[I];
104 for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind) {
105 if (std::error_code EC = Dest.mergeValueProfData(Kind, Source))
109 // We keep track of the max function count as we go for simplicity.
110 if (Dest.Counts[0] > MaxFunctionCount)
111 MaxFunctionCount = Dest.Counts[0];
113 return instrprof_error::success;
116 // Internal interface for testing purpose only.
117 void InstrProfWriter::setValueProfDataEndianness(
118 support::endianness Endianness) {
119 ValueProfDataEndianness = Endianness;
122 void InstrProfWriter::updateStringTableReferences(InstrProfRecord &I) {
123 I.updateStrings(&StringTable);
126 std::error_code InstrProfWriter::addRecord(InstrProfRecord &&I) {
127 updateStringTableReferences(I);
128 auto &ProfileDataMap = FunctionData[I.Name];
130 auto Where = ProfileDataMap.find(I.Hash);
131 if (Where == ProfileDataMap.end()) {
132 // We've never seen a function with this name and hash, add it.
133 ProfileDataMap[I.Hash] = I;
135 // We keep track of the max function count as we go for simplicity.
136 if (I.Counts[0] > MaxFunctionCount)
137 MaxFunctionCount = I.Counts[0];
138 return instrprof_error::success;
141 // We're updating a function we've seen before.
142 return combineInstrProfRecords(Where->second, I, MaxFunctionCount);
145 std::pair<uint64_t, uint64_t> InstrProfWriter::writeImpl(raw_ostream &OS) {
146 OnDiskChainedHashTableGenerator<InstrProfRecordTrait> Generator;
148 // Populate the hash table generator.
149 for (const auto &I : FunctionData)
150 Generator.insert(I.getKey(), &I.getValue());
152 using namespace llvm::support;
153 endian::Writer<little> LE(OS);
156 IndexedInstrProf::Header Header;
157 Header.Magic = IndexedInstrProf::Magic;
158 Header.Version = IndexedInstrProf::Version;
159 Header.MaxFunctionCount = MaxFunctionCount;
160 Header.HashType = static_cast<uint64_t>(IndexedInstrProf::HashType);
161 Header.HashOffset = 0;
162 int N = sizeof(IndexedInstrProf::Header) / sizeof(uint64_t);
164 // Only write out all the fields execpt 'HashOffset'. We need
165 // to remember the offset of that field to allow back patching
167 for (int I = 0; I < N - 1; I++)
168 LE.write<uint64_t>(reinterpret_cast<uint64_t *>(&Header)[I]);
170 // Save a space to write the hash table start location.
171 uint64_t HashTableStartLoc = OS.tell();
172 // Reserve the space for HashOffset field.
173 LE.write<uint64_t>(0);
174 // Write the hash table.
175 uint64_t HashTableStart = Generator.Emit(OS);
177 return std::make_pair(HashTableStartLoc, HashTableStart);
180 void InstrProfWriter::write(raw_fd_ostream &OS) {
181 // Write the hash table.
182 auto TableStart = writeImpl(OS);
184 // Go back and fill in the hash table start.
185 using namespace support;
186 OS.seek(TableStart.first);
187 // Now patch the HashOffset field previously reserved.
188 endian::Writer<little>(OS).write<uint64_t>(TableStart.second);
191 std::unique_ptr<MemoryBuffer> InstrProfWriter::writeBuffer() {
193 llvm::raw_string_ostream OS(Data);
194 // Write the hash table.
195 auto TableStart = writeImpl(OS);
198 // Go back and fill in the hash table start.
199 using namespace support;
200 uint64_t Bytes = endian::byte_swap<uint64_t, little>(TableStart.second);
201 Data.replace(TableStart.first, sizeof(uint64_t), (const char *)&Bytes,
204 // Return this in an aligned memory buffer.
205 return MemoryBuffer::getMemBufferCopy(Data);