lib/DebugInfo/DWARF/DWARFDebugAranges.cpp

   1 //===- DWARFDebugAranges.cpp ----------------------------------------------===//
   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 #include "llvm/DebugInfo/DWARF/DWARFDebugAranges.h"
  11 #include "llvm/DebugInfo/DWARF/DWARFCompileUnit.h"
  12 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
  13 #include "llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h"
  14 #include "llvm/Support/DataExtractor.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   uint32_t Offset = 0;
  27   DWARFDebugArangeSet Set;
  28
  29   while (Set.extract(DebugArangesData, &Offset)) {
  30     uint32_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().getARangeSection(),
  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     uint32_t CUOffset = CU->getOffset();
  55     if (ParsedCUOffsets.insert(CUOffset).second) {
  56       DWARFAddressRangesVector CURanges;
  57       CU->collectAddressRanges(CURanges);
  58       for (const auto &R : CURanges)
  59         appendRange(CUOffset, R.LowPC, R.HighPC);
  60     }
  61   }
  62
  63   construct();
  64 }
  65
  66 void DWARFDebugAranges::clear() {
  67   Endpoints.clear();
  68   Aranges.clear();
  69   ParsedCUOffsets.clear();
  70 }
  71
  72 void DWARFDebugAranges::appendRange(uint32_t CUOffset, uint64_t LowPC,
  73                                     uint64_t HighPC) {
  74   if (LowPC >= HighPC)
  75     return;
  76   Endpoints.emplace_back(LowPC, CUOffset, true);
  77   Endpoints.emplace_back(HighPC, CUOffset, false);
  78 }
  79
  80 void DWARFDebugAranges::construct() {
  81   std::multiset<uint32_t> ValidCUs;  // Maintain the set of CUs describing
  82                                      // a current address range.
  83   llvm::sort(Endpoints.begin(), Endpoints.end());
  84   uint64_t PrevAddress = -1ULL;
  85   for (const auto &E : Endpoints) {
  86     if (PrevAddress < E.Address && !ValidCUs.empty()) {
  87       // If the address range between two endpoints is described by some
  88       // CU, first try to extend the last range in Aranges. If we can't
  89       // do it, start a new range.
  90       if (!Aranges.empty() && Aranges.back().HighPC() == PrevAddress &&
  91           ValidCUs.find(Aranges.back().CUOffset) != ValidCUs.end()) {
  92         Aranges.back().setHighPC(E.Address);
  93       } else {
  94         Aranges.emplace_back(PrevAddress, E.Address, *ValidCUs.begin());
  95       }
  96     }
  97     // Update the set of valid CUs.
  98     if (E.IsRangeStart) {
  99       ValidCUs.insert(E.CUOffset);
 100     } else {
 101       auto CUPos = ValidCUs.find(E.CUOffset);
 102       assert(CUPos != ValidCUs.end());
 103       ValidCUs.erase(CUPos);
 104     }
 105     PrevAddress = E.Address;
 106   }
 107   assert(ValidCUs.empty());
 108
 109   // Endpoints are not needed now.
 110   Endpoints.clear();
 111   Endpoints.shrink_to_fit();
 112 }
 113
 114 uint32_t DWARFDebugAranges::findAddress(uint64_t Address) const {
 115   if (!Aranges.empty()) {
 116     Range range(Address);
 117     RangeCollIterator begin = Aranges.begin();
 118     RangeCollIterator end = Aranges.end();
 119     RangeCollIterator pos =
 120         std::lower_bound(begin, end, range);
 121
 122     if (pos != end && pos->containsAddress(Address)) {
 123       return pos->CUOffset;
 124     } else if (pos != begin) {
 125       --pos;
 126       if (pos->containsAddress(Address))
 127         return pos->CUOffset;
 128     }
 129   }
 130   return -1U;
 131 }