DWARFDebugAranges.cpp revision cd81d94322a39503e4a3e87b6ee03d4fcb3465fb 
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 "DWARFDebugAranges.h"
11#include "DWARFCompileUnit.h"
12#include "DWARFContext.h"
13#include "DWARFDebugArangeSet.h"
14#include "llvm/Support/Format.h"
15#include "llvm/Support/raw_ostream.h"
16#include <algorithm>
17#include <cassert>
18#include <set>
19using namespace llvm;
20
21void 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
38void 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
64void DWARFDebugAranges::clear() {
65  Endpoints.clear();
66  Aranges.clear();
67  ParsedCUOffsets.clear();
68}
69
70void 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
78void 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
112uint32_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}
130