InstrProfWriter.cpp revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
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 "llvm/ADT/StringExtras.h"
17#include "llvm/Support/EndianStream.h"
18#include "llvm/Support/OnDiskHashTable.h"
19
20#include "InstrProfIndexed.h"
21
22using namespace llvm;
23
24namespace {
25class InstrProfRecordTrait {
26public:
27  typedef StringRef key_type;
28  typedef StringRef key_type_ref;
29
30  typedef const InstrProfWriter::CounterData *const data_type;
31  typedef const InstrProfWriter::CounterData *const data_type_ref;
32
33  typedef uint64_t hash_value_type;
34  typedef uint64_t offset_type;
35
36  static hash_value_type ComputeHash(key_type_ref K) {
37    return IndexedInstrProf::ComputeHash(IndexedInstrProf::HashType, K);
38  }
39
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);
44
45    offset_type N = K.size();
46    LE.write<offset_type>(N);
47
48    offset_type M = (1 + V->Counts.size()) * sizeof(uint64_t);
49    LE.write<offset_type>(M);
50
51    return std::make_pair(N, M);
52  }
53
54  static void EmitKey(raw_ostream &Out, key_type_ref K, offset_type N){
55    Out.write(K.data(), N);
56  }
57
58  static void EmitData(raw_ostream &Out, key_type_ref, data_type_ref V,
59                       offset_type) {
60    using namespace llvm::support;
61    endian::Writer<little> LE(Out);
62    LE.write<uint64_t>(V->Hash);
63    for (uint64_t I : V->Counts)
64      LE.write<uint64_t>(I);
65  }
66};
67}
68
69error_code InstrProfWriter::addFunctionCounts(StringRef FunctionName,
70                                              uint64_t FunctionHash,
71                                              ArrayRef<uint64_t> Counters) {
72  auto Where = FunctionData.find(FunctionName);
73  if (Where == FunctionData.end()) {
74    // If this is the first time we've seen this function, just add it.
75    auto &Data = FunctionData[FunctionName];
76    Data.Hash = FunctionHash;
77    Data.Counts = Counters;
78    return instrprof_error::success;
79  }
80
81  auto &Data = Where->getValue();
82  // We can only add to existing functions if they match, so we check the hash
83  // and number of counters.
84  if (Data.Hash != FunctionHash)
85    return instrprof_error::hash_mismatch;
86  if (Data.Counts.size() != Counters.size())
87    return instrprof_error::count_mismatch;
88  // These match, add up the counters.
89  for (size_t I = 0, E = Counters.size(); I < E; ++I) {
90    if (Data.Counts[I] + Counters[I] < Data.Counts[I])
91      return instrprof_error::counter_overflow;
92    Data.Counts[I] += Counters[I];
93  }
94  return instrprof_error::success;
95}
96
97void InstrProfWriter::write(raw_fd_ostream &OS) {
98  OnDiskChainedHashTableGenerator<InstrProfRecordTrait> Generator;
99  uint64_t MaxFunctionCount = 0;
100
101  // Populate the hash table generator.
102  for (const auto &I : FunctionData) {
103    Generator.insert(I.getKey(), &I.getValue());
104    if (I.getValue().Counts[0] > MaxFunctionCount)
105      MaxFunctionCount = I.getValue().Counts[0];
106  }
107
108  using namespace llvm::support;
109  endian::Writer<little> LE(OS);
110
111  // Write the header.
112  LE.write<uint64_t>(IndexedInstrProf::Magic);
113  LE.write<uint64_t>(IndexedInstrProf::Version);
114  LE.write<uint64_t>(MaxFunctionCount);
115  LE.write<uint64_t>(static_cast<uint64_t>(IndexedInstrProf::HashType));
116
117  // Save a space to write the hash table start location.
118  uint64_t HashTableStartLoc = OS.tell();
119  LE.write<uint64_t>(0);
120  // Write the hash table.
121  uint64_t HashTableStart = Generator.Emit(OS);
122
123  // Go back and fill in the hash table start.
124  OS.seek(HashTableStartLoc);
125  LE.write<uint64_t>(HashTableStart);
126}
127