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   for (const auto &I : FunctionData)
115     Generator.insert(I.getKey(), &I.getValue());
116 
117   using namespace llvm::support;
118   endian::Writer<little> LE(OS);
119 
120   // Write the header.
121   LE.write<uint64_t>(IndexedInstrProf::Magic);
122   LE.write<uint64_t>(IndexedInstrProf::Version);
123   LE.write<uint64_t>(MaxFunctionCount);
124   LE.write<uint64_t>(static_cast<uint64_t>(IndexedInstrProf::HashType));
125 
126   // Save a space to write the hash table start location.
127   uint64_t HashTableStartLoc = OS.tell();
128   LE.write<uint64_t>(0);
129   // Write the hash table.
130   uint64_t HashTableStart = Generator.Emit(OS);
131 
132   // Go back and fill in the hash table start.
133   OS.seek(HashTableStartLoc);
134   LE.write<uint64_t>(HashTableStart);
135 }
136