LLVM  3.7.0
DWARFDebugAranges.cpp
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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 
14 #include "llvm/Support/Format.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;
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 
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 }
const_iterator end(StringRef path)
Get end iterator over path.
Definition: Path.cpp:240
desc_iterator_range descriptors() const
std::vector< std::pair< uint64_t, uint64_t > > DWARFAddressRangesVector
DWARFAddressRangesVector - represents a set of absolute address ranges.
const_iterator begin(StringRef path)
Get begin iterator over path.
Definition: Path.cpp:232
void generate(DWARFContext *CTX)
bool isValidOffset(uint32_t offset) const
Test the validity of offset.
std::pair< iterator, bool > insert(const ValueT &V)
Definition: DenseSet.h:147
bool extract(DataExtractor data, uint32_t *offset_ptr)
DWARFContext This data structure is the top level entity that deals with dwarf debug information pars...
Definition: DWARFContext.h:39
cu_iterator_range compile_units()
Get compile units in this context.
Definition: DWARFContext.h:87
virtual StringRef getARangeSection()=0
void clear()
Definition: DenseSet.h:60
uint32_t findAddress(uint64_t Address) const
uint32_t getCompileUnitDIEOffset() const
virtual bool isLittleEndian() const =0