lib/ProfileData/InstrProfWriter.cpp

   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
  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>
  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
  55   static void EmitKey(raw_ostream &Out, key_type_ref K, offset_type N){
  56     Out.write(K.data(), N);
  57   }
  58
  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
  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
 109 void InstrProfWriter::write(raw_fd_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   // Go back and fill in the hash table start.
 132   OS.seek(HashTableStartLoc);
 133   LE.write<uint64_t>(HashTableStart);
 134 }