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 "llvm/ADT/StringExtras.h"
  17 #include "llvm/Support/EndianStream.h"
  18 #include "llvm/Support/OnDiskHashTable.h"
  19
  20 #include "InstrProfIndexed.h"
  21
  22 using namespace llvm;
  23
  24 namespace {
  25 class InstrProfRecordTrait {
  26 public:
  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 = 0;
  49     for (const auto &Counts : *V)
  50       M += (2 + Counts.second.size()) * sizeof(uint64_t);
  51     LE.write<offset_type>(M);
  52
  53     return std::make_pair(N, M);
  54   }
  55
  56   static void EmitKey(raw_ostream &Out, key_type_ref K, offset_type N){
  57     Out.write(K.data(), N);
  58   }
  59
  60   static void EmitData(raw_ostream &Out, key_type_ref, data_type_ref V,
  61                        offset_type) {
  62     using namespace llvm::support;
  63     endian::Writer<little> LE(Out);
  64
  65     for (const auto &Counts : *V) {
  66       LE.write<uint64_t>(Counts.first);
  67       LE.write<uint64_t>(Counts.second.size());
  68       for (uint64_t I : Counts.second)
  69         LE.write<uint64_t>(I);
  70     }
  71   }
  72 };
  73 }
  74
  75 std::error_code
  76 InstrProfWriter::addFunctionCounts(StringRef FunctionName,
  77                                    uint64_t FunctionHash,
  78                                    ArrayRef<uint64_t> Counters) {
  79   auto &CounterData = FunctionData[FunctionName];
  80
  81   auto Where = CounterData.find(FunctionHash);
  82   if (Where == CounterData.end()) {
  83     // We've never seen a function with this name and hash, add it.
  84     CounterData[FunctionHash] = Counters;
  85     // We keep track of the max function count as we go for simplicity.
  86     if (Counters[0] > MaxFunctionCount)
  87       MaxFunctionCount = Counters[0];
  88     return instrprof_error::success;
  89   }
  90
  91   // We're updating a function we've seen before.
  92   auto &FoundCounters = Where->second;
  93   // If the number of counters doesn't match we either have bad data or a hash
  94   // collision.
  95   if (FoundCounters.size() != Counters.size())
  96     return instrprof_error::count_mismatch;
  97
  98   for (size_t I = 0, E = Counters.size(); I < E; ++I) {
  99     if (FoundCounters[I] + Counters[I] < FoundCounters[I])
 100       return instrprof_error::counter_overflow;
 101     FoundCounters[I] += Counters[I];
 102   }
 103   // We keep track of the max function count as we go for simplicity.
 104   if (FoundCounters[0] > MaxFunctionCount)
 105     MaxFunctionCount = FoundCounters[0];
 106
 107   return instrprof_error::success;
 108 }
 109
 110 void InstrProfWriter::write(raw_fd_ostream &OS) {
 111   OnDiskChainedHashTableGenerator<InstrProfRecordTrait> Generator;
 112
 113   // Populate the hash table generator.
 114   std::vector<uint64_t> CounterBuffer;
 115   for (const auto &I : FunctionData)
 116     Generator.insert(I.getKey(), &I.getValue());
 117
 118   using namespace llvm::support;
 119   endian::Writer<little> LE(OS);
 120
 121   // Write the header.
 122   LE.write<uint64_t>(IndexedInstrProf::Magic);
 123   LE.write<uint64_t>(IndexedInstrProf::Version);
 124   LE.write<uint64_t>(MaxFunctionCount);
 125   LE.write<uint64_t>(static_cast<uint64_t>(IndexedInstrProf::HashType));
 126
 127   // Save a space to write the hash table start location.
 128   uint64_t HashTableStartLoc = OS.tell();
 129   LE.write<uint64_t>(0);
 130   // Write the hash table.
 131   uint64_t HashTableStart = Generator.Emit(OS);
 132
 133   // Go back and fill in the hash table start.
 134   OS.seek(HashTableStartLoc);
 135   LE.write<uint64_t>(HashTableStart);
 136 }