lib/DebugInfo/DWARF/DWARFGdbIndex.cpp

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