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 = (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
  69 std::error_code
  70 InstrProfWriter::addFunctionCounts(StringRef FunctionName,
  71                                    uint64_t FunctionHash,
  72                                    ArrayRef<uint64_t> Counters) {
  73   auto Where = FunctionData.find(FunctionName);
  74   if (Where == FunctionData.end()) {
  75     // If this is the first time we've seen this function, just add it.
  76     auto &Data = FunctionData[FunctionName];
  77     Data.Hash = FunctionHash;
  78     Data.Counts = Counters;
  79     return instrprof_error::success;
  80   }
  81
  82   auto &Data = Where->getValue();
  83   // We can only add to existing functions if they match, so we check the hash
  84   // and number of counters.
  85   if (Data.Hash != FunctionHash)
  86     return instrprof_error::hash_mismatch;
  87   if (Data.Counts.size() != Counters.size())
  88     return instrprof_error::count_mismatch;
  89   // These match, add up the counters.
  90   for (size_t I = 0, E = Counters.size(); I < E; ++I) {
  91     if (Data.Counts[I] + Counters[I] < Data.Counts[I])
  92       return instrprof_error::counter_overflow;
  93     Data.Counts[I] += Counters[I];
  94   }
  95   return instrprof_error::success;
  96 }
  97
  98 void InstrProfWriter::write(raw_fd_ostream &OS) {
  99   OnDiskChainedHashTableGenerator<InstrProfRecordTrait> Generator;
 100   uint64_t MaxFunctionCount = 0;
 101
 102   // Populate the hash table generator.
 103   for (const auto &I : FunctionData) {
 104     Generator.insert(I.getKey(), &I.getValue());
 105     if (I.getValue().Counts[0] > MaxFunctionCount)
 106       MaxFunctionCount = I.getValue().Counts[0];
 107   }
 108
 109   using namespace llvm::support;
 110   endian::Writer<little> LE(OS);
 111
 112   // Write the header.
 113   LE.write<uint64_t>(IndexedInstrProf::Magic);
 114   LE.write<uint64_t>(IndexedInstrProf::Version);
 115   LE.write<uint64_t>(MaxFunctionCount);
 116   LE.write<uint64_t>(static_cast<uint64_t>(IndexedInstrProf::HashType));
 117
 118   // Save a space to write the hash table start location.
 119   uint64_t HashTableStartLoc = OS.tell();
 120   LE.write<uint64_t>(0);
 121   // Write the hash table.
 122   uint64_t HashTableStart = Generator.Emit(OS);
 123
 124   // Go back and fill in the hash table start.
 125   OS.seek(HashTableStartLoc);
 126   LE.write<uint64_t>(HashTableStart);
 127 }