DWARFDebugAranges.cpp revision 341825 
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
21using namespace llvm;
22
23void 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
40void 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
66void DWARFDebugAranges::clear() {
67  Endpoints.clear();
68  Aranges.clear();
69  ParsedCUOffsets.clear();
70}
71
72void 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
80void 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
114uint32_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}
132