src/llvm/lib/DebugInfo/DWARFDebugAranges.cpp

   1 //===-- DWARFDebugAranges.cpp -----------------------------------*- C++ -*-===//
   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/DWARFDebugAranges.h"
  11 #include "llvm/DebugInfo/DWARFCompileUnit.h"
  12 #include "llvm/DebugInfo/DWARFContext.h"
  13 #include "llvm/DebugInfo/DWARFDebugArangeSet.h"
  14 #include "llvm/Support/Format.h"
  15 #include "llvm/Support/raw_ostream.h"
  16 #include <algorithm>
  17 #include <cassert>
  18 #include <set>
  19 using namespace llvm;
  20
  21 void DWARFDebugAranges::extract(DataExtractor DebugArangesData) {
  22   if (!DebugArangesData.isValidOffset(0))
  23     return;
  24   uint32_t Offset = 0;
  25   DWARFDebugArangeSet Set;
  26
  27   while (Set.extract(DebugArangesData, &Offset)) {
  28     uint32_t CUOffset = Set.getCompileUnitDIEOffset();
  29     for (const auto &Desc : Set.descriptors()) {
  30       uint64_t LowPC = Desc.Address;
  31       uint64_t HighPC = Desc.getEndAddress();
  32       appendRange(CUOffset, LowPC, HighPC);
  33     }
  34     ParsedCUOffsets.insert(CUOffset);
  35   }
  36 }
  37
  38 void DWARFDebugAranges::generate(DWARFContext *CTX) {
  39   clear();
  40   if (!CTX)
  41     return;
  42
  43   // Extract aranges from .debug_aranges section.
  44   DataExtractor ArangesData(CTX->getARangeSection(), CTX->isLittleEndian(), 0);
  45   extract(ArangesData);
  46
  47   // Generate aranges from DIEs: even if .debug_aranges section is present,
  48   // it may describe only a small subset of compilation units, so we need to
  49   // manually build aranges for the rest of them.
  50   for (const auto &CU : CTX->compile_units()) {
  51     uint32_t CUOffset = CU->getOffset();
  52     if (ParsedCUOffsets.insert(CUOffset).second) {
  53       DWARFAddressRangesVector CURanges;
  54       CU->collectAddressRanges(CURanges);
  55       for (const auto &R : CURanges) {
  56         appendRange(CUOffset, R.first, R.second);
  57       }
  58     }
  59   }
  60
  61   construct();
  62 }
  63
  64 void DWARFDebugAranges::clear() {
  65   Endpoints.clear();
  66   Aranges.clear();
  67   ParsedCUOffsets.clear();
  68 }
  69
  70 void DWARFDebugAranges::appendRange(uint32_t CUOffset, uint64_t LowPC,
  71                                     uint64_t HighPC) {
  72   if (LowPC >= HighPC)
  73     return;
  74   Endpoints.emplace_back(LowPC, CUOffset, true);
  75   Endpoints.emplace_back(HighPC, CUOffset, false);
  76 }
  77
  78 void DWARFDebugAranges::construct() {
  79   std::multiset<uint32_t> ValidCUs;  // Maintain the set of CUs describing
  80                                      // a current address range.
  81   std::sort(Endpoints.begin(), Endpoints.end());
  82   uint64_t PrevAddress = -1ULL;
  83   for (const auto &E : Endpoints) {
  84     if (PrevAddress < E.Address && ValidCUs.size() > 0) {
  85       // If the address range between two endpoints is described by some
  86       // CU, first try to extend the last range in Aranges. If we can't
  87       // do it, start a new range.
  88       if (!Aranges.empty() && Aranges.back().HighPC() == PrevAddress &&
  89           ValidCUs.find(Aranges.back().CUOffset) != ValidCUs.end()) {
  90         Aranges.back().setHighPC(E.Address);
  91       } else {
  92         Aranges.emplace_back(PrevAddress, E.Address, *ValidCUs.begin());
  93       }
  94     }
  95     // Update the set of valid CUs.
  96     if (E.IsRangeStart) {
  97       ValidCUs.insert(E.CUOffset);
  98     } else {
  99       auto CUPos = ValidCUs.find(E.CUOffset);
 100       assert(CUPos != ValidCUs.end());
 101       ValidCUs.erase(CUPos);
 102     }
 103     PrevAddress = E.Address;
 104   }
 105   assert(ValidCUs.empty());
 106
 107   // Endpoints are not needed now.
 108   std::vector<RangeEndpoint> EmptyEndpoints;
 109   EmptyEndpoints.swap(Endpoints);
 110 }
 111
 112 uint32_t DWARFDebugAranges::findAddress(uint64_t Address) const {
 113   if (!Aranges.empty()) {
 114     Range range(Address);
 115     RangeCollIterator begin = Aranges.begin();
 116     RangeCollIterator end = Aranges.end();
 117     RangeCollIterator pos =
 118         std::lower_bound(begin, end, range);
 119
 120     if (pos != end && pos->containsAddress(Address)) {
 121       return pos->CUOffset;
 122     } else if (pos != begin) {
 123       --pos;
 124       if (pos->containsAddress(Address))
 125         return pos->CUOffset;
 126     }
 127   }
 128   return -1U;
 129 }