lib/DebugInfo/DWARF/DWARFDebugAranges.cpp

   1 //===- DWARFDebugAranges.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/DWARFDebugAranges.h"
  10 #include "llvm/DebugInfo/DWARF/DWARFCompileUnit.h"
  11 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
  12 #include "llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h"
  13 #include "llvm/Support/DataExtractor.h"
  14 #include "llvm/Support/WithColor.h"
  15 #include <algorithm>
  16 #include <cassert>
  17 #include <cstdint>
  18 #include <set>
  19 #include <vector>
  20
  21 using namespace llvm;
  22
  23 void DWARFDebugAranges::extract(DataExtractor DebugArangesData) {
  24   if (!DebugArangesData.isValidOffset(0))
  25     return;
  26   uint64_t Offset = 0;
  27   DWARFDebugArangeSet Set;
  28
  29   while (Set.extract(DebugArangesData, &Offset)) {
  30     uint64_t CUOffset = Set.getCompileUnitDIEOffset();
  31     for (const auto &Desc : Set.descriptors()) {
  32       uint64_t LowPC = Desc.Address;
  33       uint64_t HighPC = Desc.getEndAddress();
  34       appendRange(CUOffset, LowPC, HighPC);
  35     }
  36     ParsedCUOffsets.insert(CUOffset);
  37   }
  38 }
  39
  40 void DWARFDebugAranges::generate(DWARFContext *CTX) {
  41   clear();
  42   if (!CTX)
  43     return;
  44
  45   // Extract aranges from .debug_aranges section.
  46   DataExtractor ArangesData(CTX->getDWARFObj().getArangesSection(),
  47                             CTX->isLittleEndian(), 0);
  48   extract(ArangesData);
  49
  50   // Generate aranges from DIEs: even if .debug_aranges section is present,
  51   // it may describe only a small subset of compilation units, so we need to
  52   // manually build aranges for the rest of them.
  53   for (const auto &CU : CTX->compile_units()) {
  54     uint64_t CUOffset = CU->getOffset();
  55     if (ParsedCUOffsets.insert(CUOffset).second) {
  56       Expected<DWARFAddressRangesVector> CURanges = CU->collectAddressRanges();
  57       if (!CURanges)
  58         WithColor::error() << toString(CURanges.takeError()) << '\n';
  59       else
  60         for (const auto &R : *CURanges)
  61           appendRange(CUOffset, R.LowPC, R.HighPC);
  62     }
  63   }
  64
  65   construct();
  66 }
  67
  68 void DWARFDebugAranges::clear() {
  69   Endpoints.clear();
  70   Aranges.clear();
  71   ParsedCUOffsets.clear();
  72 }
  73
  74 void DWARFDebugAranges::appendRange(uint64_t CUOffset, uint64_t LowPC,
  75                                     uint64_t HighPC) {
  76   if (LowPC >= HighPC)
  77     return;
  78   Endpoints.emplace_back(LowPC, CUOffset, true);
  79   Endpoints.emplace_back(HighPC, CUOffset, false);
  80 }
  81
  82 void DWARFDebugAranges::construct() {
  83   std::multiset<uint64_t> ValidCUs;  // Maintain the set of CUs describing
  84                                      // a current address range.
  85   llvm::sort(Endpoints);
  86   uint64_t PrevAddress = -1ULL;
  87   for (const auto &E : Endpoints) {
  88     if (PrevAddress < E.Address && !ValidCUs.empty()) {
  89       // If the address range between two endpoints is described by some
  90       // CU, first try to extend the last range in Aranges. If we can't
  91       // do it, start a new range.
  92       if (!Aranges.empty() && Aranges.back().HighPC() == PrevAddress &&
  93           ValidCUs.find(Aranges.back().CUOffset) != ValidCUs.end()) {
  94         Aranges.back().setHighPC(E.Address);
  95       } else {
  96         Aranges.emplace_back(PrevAddress, E.Address, *ValidCUs.begin());
  97       }
  98     }
  99     // Update the set of valid CUs.
 100     if (E.IsRangeStart) {
 101       ValidCUs.insert(E.CUOffset);
 102     } else {
 103       auto CUPos = ValidCUs.find(E.CUOffset);
 104       assert(CUPos != ValidCUs.end());
 105       ValidCUs.erase(CUPos);
 106     }
 107     PrevAddress = E.Address;
 108   }
 109   assert(ValidCUs.empty());
 110
 111   // Endpoints are not needed now.
 112   Endpoints.clear();
 113   Endpoints.shrink_to_fit();
 114 }
 115
 116 uint32_t DWARFDebugAranges::findAddress(uint64_t Address) const {
 117   RangeCollIterator It =
 118       partition_point(Aranges, [=](Range R) { return R.HighPC() <= Address; });
 119   if (It != Aranges.end() && It->LowPC <= Address)
 120     return It->CUOffset;
 121   return -1U;
 122 }