1//===- DWARFGdbIndex.cpp --------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "llvm/DebugInfo/DWARF/DWARFGdbIndex.h"
10#include "llvm/ADT/SmallVector.h"
11#include "llvm/ADT/StringRef.h"
12#include "llvm/Support/DataExtractor.h"
13#include "llvm/Support/Format.h"
14#include "llvm/Support/FormatVariadic.h"
15#include "llvm/Support/raw_ostream.h"
16#include <cassert>
17#include <cinttypes>
18#include <cstdint>
19#include <set>
20#include <utility>
21
22using namespace llvm;
23
24// .gdb_index section format reference:
25// https://sourceware.org/gdb/onlinedocs/gdb/Index-Section-Format.html
26
27void DWARFGdbIndex::dumpCUList(raw_ostream &OS) const {
28  OS << format("\n  CU list offset = 0x%x, has %" PRId64 " entries:",
29               CuListOffset, (uint64_t)CuList.size())
30     << '\n';
31  uint32_t I = 0;
32  for (const CompUnitEntry &CU : CuList)
33    OS << format("    %d: Offset = 0x%llx, Length = 0x%llx\n", I++, CU.Offset,
34                 CU.Length);
35}
36
37void DWARFGdbIndex::dumpTUList(raw_ostream &OS) const {
38  OS << formatv("\n  Types CU list offset = {0:x}, has {1} entries:\n",
39                TuListOffset, TuList.size());
40  uint32_t I = 0;
41  for (const TypeUnitEntry &TU : TuList)
42    OS << formatv("    {0}: offset = {1:x8}, type_offset = {2:x8}, "
43                  "type_signature = {3:x16}\n",
44                  I++, TU.Offset, TU.TypeOffset, TU.TypeSignature);
45}
46
47void DWARFGdbIndex::dumpAddressArea(raw_ostream &OS) const {
48  OS << format("\n  Address area offset = 0x%x, has %" PRId64 " entries:",
49               AddressAreaOffset, (uint64_t)AddressArea.size())
50     << '\n';
51  for (const AddressEntry &Addr : AddressArea)
52    OS << format(
53        "    Low/High address = [0x%llx, 0x%llx) (Size: 0x%llx), CU id = %d\n",
54        Addr.LowAddress, Addr.HighAddress, Addr.HighAddress - Addr.LowAddress,
55        Addr.CuIndex);
56}
57
58void DWARFGdbIndex::dumpSymbolTable(raw_ostream &OS) const {
59  OS << format("\n  Symbol table offset = 0x%x, size = %" PRId64
60               ", filled slots:",
61               SymbolTableOffset, (uint64_t)SymbolTable.size())
62     << '\n';
63  uint32_t I = -1;
64  for (const SymTableEntry &E : SymbolTable) {
65    ++I;
66    if (!E.NameOffset && !E.VecOffset)
67      continue;
68
69    OS << format("    %d: Name offset = 0x%x, CU vector offset = 0x%x\n", I,
70                 E.NameOffset, E.VecOffset);
71
72    StringRef Name = ConstantPoolStrings.substr(
73        ConstantPoolOffset - StringPoolOffset + E.NameOffset);
74
75    auto CuVector = llvm::find_if(
76        ConstantPoolVectors,
77        [&](const std::pair<uint32_t, SmallVector<uint32_t, 0>> &V) {
78          return V.first == E.VecOffset;
79        });
80    assert(CuVector != ConstantPoolVectors.end() && "Invalid symbol table");
81    uint32_t CuVectorId = CuVector - ConstantPoolVectors.begin();
82    OS << format("      String name: %s, CU vector index: %d\n", Name.data(),
83                 CuVectorId);
84  }
85}
86
87void DWARFGdbIndex::dumpConstantPool(raw_ostream &OS) const {
88  OS << format("\n  Constant pool offset = 0x%x, has %" PRId64 " CU vectors:",
89               ConstantPoolOffset, (uint64_t)ConstantPoolVectors.size());
90  uint32_t I = 0;
91  for (const auto &V : ConstantPoolVectors) {
92    OS << format("\n    %d(0x%x): ", I++, V.first);
93    for (uint32_t Val : V.second)
94      OS << format("0x%x ", Val);
95  }
96  OS << '\n';
97}
98
99void DWARFGdbIndex::dump(raw_ostream &OS) {
100  if (HasError) {
101    OS << "\n<error parsing>\n";
102    return;
103  }
104
105  if (HasContent) {
106    OS << "  Version = " << Version << '\n';
107    dumpCUList(OS);
108    dumpTUList(OS);
109    dumpAddressArea(OS);
110    dumpSymbolTable(OS);
111    dumpConstantPool(OS);
112  }
113}
114
115bool DWARFGdbIndex::parseImpl(DataExtractor Data) {
116  uint64_t Offset = 0;
117
118  // Only version 7 and 8 are supported at this moment.
119  Version = Data.getU32(&Offset);
120  if (Version != 7 && Version != 8)
121    return false;
122
123  CuListOffset = Data.getU32(&Offset);
124  TuListOffset = Data.getU32(&Offset);
125  AddressAreaOffset = Data.getU32(&Offset);
126  SymbolTableOffset = Data.getU32(&Offset);
127  ConstantPoolOffset = Data.getU32(&Offset);
128
129  if (Offset != CuListOffset)
130    return false;
131
132  uint32_t CuListSize = (TuListOffset - CuListOffset) / 16;
133  CuList.reserve(CuListSize);
134  for (uint32_t i = 0; i < CuListSize; ++i) {
135    uint64_t CuOffset = Data.getU64(&Offset);
136    uint64_t CuLength = Data.getU64(&Offset);
137    CuList.push_back({CuOffset, CuLength});
138  }
139
140  // CU Types are no longer needed as DWARF skeleton type units never made it
141  // into the standard.
142  uint32_t TuListSize = (AddressAreaOffset - TuListOffset) / 24;
143  TuList.resize(TuListSize);
144  for (uint32_t I = 0; I < TuListSize; ++I) {
145    uint64_t CuOffset = Data.getU64(&Offset);
146    uint64_t TypeOffset = Data.getU64(&Offset);
147    uint64_t Signature = Data.getU64(&Offset);
148    TuList[I] = {CuOffset, TypeOffset, Signature};
149  }
150
151  uint32_t AddressAreaSize = (SymbolTableOffset - AddressAreaOffset) / 20;
152  AddressArea.reserve(AddressAreaSize);
153  for (uint32_t i = 0; i < AddressAreaSize; ++i) {
154    uint64_t LowAddress = Data.getU64(&Offset);
155    uint64_t HighAddress = Data.getU64(&Offset);
156    uint32_t CuIndex = Data.getU32(&Offset);
157    AddressArea.push_back({LowAddress, HighAddress, CuIndex});
158  }
159
160  // The symbol table. This is an open addressed hash table. The size of the
161  // hash table is always a power of 2.
162  // Each slot in the hash table consists of a pair of offset_type values. The
163  // first value is the offset of the symbol's name in the constant pool. The
164  // second value is the offset of the CU vector in the constant pool.
165  // If both values are 0, then this slot in the hash table is empty. This is ok
166  // because while 0 is a valid constant pool index, it cannot be a valid index
167  // for both a string and a CU vector.
168  uint32_t SymTableSize = (ConstantPoolOffset - SymbolTableOffset) / 8;
169  SymbolTable.reserve(SymTableSize);
170  std::set<uint32_t> CUOffsets;
171  for (uint32_t i = 0; i < SymTableSize; ++i) {
172    uint32_t NameOffset = Data.getU32(&Offset);
173    uint32_t CuVecOffset = Data.getU32(&Offset);
174    SymbolTable.push_back({NameOffset, CuVecOffset});
175    if (NameOffset || CuVecOffset)
176      CUOffsets.insert(CuVecOffset);
177  }
178
179  // The constant pool. CU vectors are stored first, followed by strings.
180  // The first value is the number of CU indices in the vector. Each subsequent
181  // value is the index and symbol attributes of a CU in the CU list.
182  for (auto CUOffset : CUOffsets) {
183    Offset = ConstantPoolOffset + CUOffset;
184    ConstantPoolVectors.emplace_back(0, SmallVector<uint32_t, 0>());
185    auto &Vec = ConstantPoolVectors.back();
186    Vec.first = Offset - ConstantPoolOffset;
187
188    uint32_t Num = Data.getU32(&Offset);
189    for (uint32_t J = 0; J < Num; ++J)
190      Vec.second.push_back(Data.getU32(&Offset));
191  }
192
193  ConstantPoolStrings = Data.getData().drop_front(Offset);
194  StringPoolOffset = Offset;
195  return true;
196}
197
198void DWARFGdbIndex::parse(DataExtractor Data) {
199  HasContent = !Data.getData().empty();
200  HasError = HasContent && !parseImpl(Data);
201}
202