DWARFDebugAranges.cpp revision 344779 
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 "llvm/Support/WithColor.h"
16#include <algorithm>
17#include <cassert>
18#include <cstdint>
19#include <set>
20#include <vector>
21
22using namespace llvm;
23
24void DWARFDebugAranges::extract(DataExtractor DebugArangesData) {
25  if (!DebugArangesData.isValidOffset(0))
26    return;
27  uint32_t Offset = 0;
28  DWARFDebugArangeSet Set;
29
30  while (Set.extract(DebugArangesData, &Offset)) {
31    uint32_t CUOffset = Set.getCompileUnitDIEOffset();
32    for (const auto &Desc : Set.descriptors()) {
33      uint64_t LowPC = Desc.Address;
34      uint64_t HighPC = Desc.getEndAddress();
35      appendRange(CUOffset, LowPC, HighPC);
36    }
37    ParsedCUOffsets.insert(CUOffset);
38  }
39}
40
41void DWARFDebugAranges::generate(DWARFContext *CTX) {
42  clear();
43  if (!CTX)
44    return;
45
46  // Extract aranges from .debug_aranges section.
47  DataExtractor ArangesData(CTX->getDWARFObj().getARangeSection(),
48                            CTX->isLittleEndian(), 0);
49  extract(ArangesData);
50
51  // Generate aranges from DIEs: even if .debug_aranges section is present,
52  // it may describe only a small subset of compilation units, so we need to
53  // manually build aranges for the rest of them.
54  for (const auto &CU : CTX->compile_units()) {
55    uint32_t CUOffset = CU->getOffset();
56    if (ParsedCUOffsets.insert(CUOffset).second) {
57      Expected<DWARFAddressRangesVector> CURanges = CU->collectAddressRanges();
58      if (!CURanges)
59        WithColor::error() << toString(CURanges.takeError()) << '\n';
60      else
61        for (const auto &R : *CURanges)
62          appendRange(CUOffset, R.LowPC, R.HighPC);
63    }
64  }
65
66  construct();
67}
68
69void DWARFDebugAranges::clear() {
70  Endpoints.clear();
71  Aranges.clear();
72  ParsedCUOffsets.clear();
73}
74
75void DWARFDebugAranges::appendRange(uint32_t CUOffset, uint64_t LowPC,
76                                    uint64_t HighPC) {
77  if (LowPC >= HighPC)
78    return;
79  Endpoints.emplace_back(LowPC, CUOffset, true);
80  Endpoints.emplace_back(HighPC, CUOffset, false);
81}
82
83void DWARFDebugAranges::construct() {
84  std::multiset<uint32_t> ValidCUs;  // Maintain the set of CUs describing
85                                     // a current address range.
86  llvm::sort(Endpoints);
87  uint64_t PrevAddress = -1ULL;
88  for (const auto &E : Endpoints) {
89    if (PrevAddress < E.Address && !ValidCUs.empty()) {
90      // If the address range between two endpoints is described by some
91      // CU, first try to extend the last range in Aranges. If we can't
92      // do it, start a new range.
93      if (!Aranges.empty() && Aranges.back().HighPC() == PrevAddress &&
94          ValidCUs.find(Aranges.back().CUOffset) != ValidCUs.end()) {
95        Aranges.back().setHighPC(E.Address);
96      } else {
97        Aranges.emplace_back(PrevAddress, E.Address, *ValidCUs.begin());
98      }
99    }
100    // Update the set of valid CUs.
101    if (E.IsRangeStart) {
102      ValidCUs.insert(E.CUOffset);
103    } else {
104      auto CUPos = ValidCUs.find(E.CUOffset);
105      assert(CUPos != ValidCUs.end());
106      ValidCUs.erase(CUPos);
107    }
108    PrevAddress = E.Address;
109  }
110  assert(ValidCUs.empty());
111
112  // Endpoints are not needed now.
113  Endpoints.clear();
114  Endpoints.shrink_to_fit();
115}
116
117uint32_t DWARFDebugAranges::findAddress(uint64_t Address) const {
118  if (!Aranges.empty()) {
119    Range range(Address);
120    RangeCollIterator begin = Aranges.begin();
121    RangeCollIterator end = Aranges.end();
122    RangeCollIterator pos =
123        std::lower_bound(begin, end, range);
124
125    if (pos != end && pos->containsAddress(Address)) {
126      return pos->CUOffset;
127    } else if (pos != begin) {
128      --pos;
129      if (pos->containsAddress(Address))
130        return pos->CUOffset;
131    }
132  }
133  return -1U;
134}
135