1 //=-- InstrProfWriter.cpp - Instrumented profiling writer -------------------=//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains support for writing profiling data for clang's
11 // instrumentation based PGO and coverage.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/ProfileData/InstrProfWriter.h"
16 #include "InstrProfIndexed.h"
17 #include "llvm/ADT/StringExtras.h"
18 #include "llvm/Support/EndianStream.h"
19 #include "llvm/Support/OnDiskHashTable.h"
20
21 using namespace llvm;
22
23 namespace {
24 class InstrProfRecordTrait {
25 public:
26 typedef StringRef key_type;
27 typedef StringRef key_type_ref;
28
29 typedef const InstrProfWriter::CounterData *const data_type;
30 typedef const InstrProfWriter::CounterData *const data_type_ref;
31
32 typedef uint64_t hash_value_type;
33 typedef uint64_t offset_type;
34
ComputeHash(key_type_ref K)35 static hash_value_type ComputeHash(key_type_ref K) {
36 return IndexedInstrProf::ComputeHash(IndexedInstrProf::HashType, K);
37 }
38
39 static std::pair<offset_type, offset_type>
EmitKeyDataLength(raw_ostream & Out,key_type_ref K,data_type_ref V)40 EmitKeyDataLength(raw_ostream &Out, key_type_ref K, data_type_ref V) {
41 using namespace llvm::support;
42 endian::Writer<little> LE(Out);
43
44 offset_type N = K.size();
45 LE.write<offset_type>(N);
46
47 offset_type M = 0;
48 for (const auto &Counts : *V)
49 M += (2 + Counts.second.size()) * sizeof(uint64_t);
50 LE.write<offset_type>(M);
51
52 return std::make_pair(N, M);
53 }
54
EmitKey(raw_ostream & Out,key_type_ref K,offset_type N)55 static void EmitKey(raw_ostream &Out, key_type_ref K, offset_type N){
56 Out.write(K.data(), N);
57 }
58
EmitData(raw_ostream & Out,key_type_ref,data_type_ref V,offset_type)59 static void EmitData(raw_ostream &Out, key_type_ref, data_type_ref V,
60 offset_type) {
61 using namespace llvm::support;
62 endian::Writer<little> LE(Out);
63
64 for (const auto &Counts : *V) {
65 LE.write<uint64_t>(Counts.first);
66 LE.write<uint64_t>(Counts.second.size());
67 for (uint64_t I : Counts.second)
68 LE.write<uint64_t>(I);
69 }
70 }
71 };
72 }
73
74 std::error_code
addFunctionCounts(StringRef FunctionName,uint64_t FunctionHash,ArrayRef<uint64_t> Counters)75 InstrProfWriter::addFunctionCounts(StringRef FunctionName,
76 uint64_t FunctionHash,
77 ArrayRef<uint64_t> Counters) {
78 auto &CounterData = FunctionData[FunctionName];
79
80 auto Where = CounterData.find(FunctionHash);
81 if (Where == CounterData.end()) {
82 // We've never seen a function with this name and hash, add it.
83 CounterData[FunctionHash] = Counters;
84 // We keep track of the max function count as we go for simplicity.
85 if (Counters[0] > MaxFunctionCount)
86 MaxFunctionCount = Counters[0];
87 return instrprof_error::success;
88 }
89
90 // We're updating a function we've seen before.
91 auto &FoundCounters = Where->second;
92 // If the number of counters doesn't match we either have bad data or a hash
93 // collision.
94 if (FoundCounters.size() != Counters.size())
95 return instrprof_error::count_mismatch;
96
97 for (size_t I = 0, E = Counters.size(); I < E; ++I) {
98 if (FoundCounters[I] + Counters[I] < FoundCounters[I])
99 return instrprof_error::counter_overflow;
100 FoundCounters[I] += Counters[I];
101 }
102 // We keep track of the max function count as we go for simplicity.
103 if (FoundCounters[0] > MaxFunctionCount)
104 MaxFunctionCount = FoundCounters[0];
105
106 return instrprof_error::success;
107 }
108
writeImpl(raw_ostream & OS)109 std::pair<uint64_t, uint64_t> InstrProfWriter::writeImpl(raw_ostream &OS) {
110 OnDiskChainedHashTableGenerator<InstrProfRecordTrait> Generator;
111
112 // Populate the hash table generator.
113 for (const auto &I : FunctionData)
114 Generator.insert(I.getKey(), &I.getValue());
115
116 using namespace llvm::support;
117 endian::Writer<little> LE(OS);
118
119 // Write the header.
120 LE.write<uint64_t>(IndexedInstrProf::Magic);
121 LE.write<uint64_t>(IndexedInstrProf::Version);
122 LE.write<uint64_t>(MaxFunctionCount);
123 LE.write<uint64_t>(static_cast<uint64_t>(IndexedInstrProf::HashType));
124
125 // Save a space to write the hash table start location.
126 uint64_t HashTableStartLoc = OS.tell();
127 LE.write<uint64_t>(0);
128 // Write the hash table.
129 uint64_t HashTableStart = Generator.Emit(OS);
130
131 return std::make_pair(HashTableStartLoc, HashTableStart);
132 }
133
write(raw_fd_ostream & OS)134 void InstrProfWriter::write(raw_fd_ostream &OS) {
135 // Write the hash table.
136 auto TableStart = writeImpl(OS);
137
138 // Go back and fill in the hash table start.
139 using namespace support;
140 OS.seek(TableStart.first);
141 endian::Writer<little>(OS).write<uint64_t>(TableStart.second);
142 }
143
writeBuffer()144 std::unique_ptr<MemoryBuffer> InstrProfWriter::writeBuffer() {
145 std::string Data;
146 llvm::raw_string_ostream OS(Data);
147 // Write the hash table.
148 auto TableStart = writeImpl(OS);
149 OS.flush();
150
151 // Go back and fill in the hash table start.
152 using namespace support;
153 uint64_t Bytes = endian::byte_swap<uint64_t, little>(TableStart.second);
154 Data.replace(TableStart.first, sizeof(uint64_t), (const char *)&Bytes,
155 sizeof(uint64_t));
156
157 // Return this in an aligned memory buffer.
158 return MemoryBuffer::getMemBufferCopy(Data);
159 }
160