DWARFDebugAranges.cpp revision 321369 
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->getARangeSection(), CTX->isLittleEndian(), 0);
47  extract(ArangesData);
48
49  // Generate aranges from DIEs: even if .debug_aranges section is present,
50  // it may describe only a small subset of compilation units, so we need to
51  // manually build aranges for the rest of them.
52  for (const auto &CU : CTX->compile_units()) {
53    uint32_t CUOffset = CU->getOffset();
54    if (ParsedCUOffsets.insert(CUOffset).second) {
55      DWARFAddressRangesVector CURanges;
56      CU->collectAddressRanges(CURanges);
57      for (const auto &R : CURanges)
58        appendRange(CUOffset, R.LowPC, R.HighPC);
59    }
60  }
61
62  construct();
63}
64
65void DWARFDebugAranges::clear() {
66  Endpoints.clear();
67  Aranges.clear();
68  ParsedCUOffsets.clear();
69}
70
71void DWARFDebugAranges::appendRange(uint32_t CUOffset, uint64_t LowPC,
72                                    uint64_t HighPC) {
73  if (LowPC >= HighPC)
74    return;
75  Endpoints.emplace_back(LowPC, CUOffset, true);
76  Endpoints.emplace_back(HighPC, CUOffset, false);
77}
78
79void DWARFDebugAranges::construct() {
80  std::multiset<uint32_t> ValidCUs;  // Maintain the set of CUs describing
81                                     // a current address range.
82  std::sort(Endpoints.begin(), Endpoints.end());
83  uint64_t PrevAddress = -1ULL;
84  for (const auto &E : Endpoints) {
85    if (PrevAddress < E.Address && !ValidCUs.empty()) {
86      // If the address range between two endpoints is described by some
87      // CU, first try to extend the last range in Aranges. If we can't
88      // do it, start a new range.
89      if (!Aranges.empty() && Aranges.back().HighPC() == PrevAddress &&
90          ValidCUs.find(Aranges.back().CUOffset) != ValidCUs.end()) {
91        Aranges.back().setHighPC(E.Address);
92      } else {
93        Aranges.emplace_back(PrevAddress, E.Address, *ValidCUs.begin());
94      }
95    }
96    // Update the set of valid CUs.
97    if (E.IsRangeStart) {
98      ValidCUs.insert(E.CUOffset);
99    } else {
100      auto CUPos = ValidCUs.find(E.CUOffset);
101      assert(CUPos != ValidCUs.end());
102      ValidCUs.erase(CUPos);
103    }
104    PrevAddress = E.Address;
105  }
106  assert(ValidCUs.empty());
107
108  // Endpoints are not needed now.
109  std::vector<RangeEndpoint> EmptyEndpoints;
110  EmptyEndpoints.swap(Endpoints);
111}
112
113uint32_t DWARFDebugAranges::findAddress(uint64_t Address) const {
114  if (!Aranges.empty()) {
115    Range range(Address);
116    RangeCollIterator begin = Aranges.begin();
117    RangeCollIterator end = Aranges.end();
118    RangeCollIterator pos =
119        std::lower_bound(begin, end, range);
120
121    if (pos != end && pos->containsAddress(Address)) {
122      return pos->CUOffset;
123    } else if (pos != begin) {
124      --pos;
125      if (pos->containsAddress(Address))
126        return pos->CUOffset;
127    }
128  }
129  return -1U;
130}
131