1//===- DWARFDebugAranges.cpp ----------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "llvm/DebugInfo/DWARF/DWARFDebugAranges.h"
10#include "llvm/DebugInfo/DWARF/DWARFAddressRange.h"
11#include "llvm/DebugInfo/DWARF/DWARFContext.h"
12#include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
13#include "llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h"
14#include "llvm/DebugInfo/DWARF/DWARFObject.h"
15#include "llvm/DebugInfo/DWARF/DWARFUnit.h"
16#include <algorithm>
17#include <cassert>
18#include <cstdint>
19#include <set>
20
21using namespace llvm;
22
23void DWARFDebugAranges::extract(
24    DWARFDataExtractor DebugArangesData,
25    function_ref<void(Error)> RecoverableErrorHandler,
26    function_ref<void(Error)> WarningHandler) {
27  if (!DebugArangesData.isValidOffset(0))
28    return;
29  uint64_t Offset = 0;
30  DWARFDebugArangeSet Set;
31
32  while (DebugArangesData.isValidOffset(Offset)) {
33    if (Error E = Set.extract(DebugArangesData, &Offset, WarningHandler)) {
34      RecoverableErrorHandler(std::move(E));
35      return;
36    }
37    uint64_t CUOffset = Set.getCompileUnitDIEOffset();
38    for (const auto &Desc : Set.descriptors()) {
39      uint64_t LowPC = Desc.Address;
40      uint64_t HighPC = Desc.getEndAddress();
41      appendRange(CUOffset, LowPC, HighPC);
42    }
43    ParsedCUOffsets.insert(CUOffset);
44  }
45}
46
47void DWARFDebugAranges::generate(DWARFContext *CTX) {
48  clear();
49  if (!CTX)
50    return;
51
52  // Extract aranges from .debug_aranges section.
53  DWARFDataExtractor ArangesData(CTX->getDWARFObj().getArangesSection(),
54                                 CTX->isLittleEndian(), 0);
55  extract(ArangesData, CTX->getRecoverableErrorHandler(),
56          CTX->getWarningHandler());
57
58  // Generate aranges from DIEs: even if .debug_aranges section is present,
59  // it may describe only a small subset of compilation units, so we need to
60  // manually build aranges for the rest of them.
61  for (const auto &CU : CTX->compile_units()) {
62    uint64_t CUOffset = CU->getOffset();
63    if (ParsedCUOffsets.insert(CUOffset).second) {
64      Expected<DWARFAddressRangesVector> CURanges = CU->collectAddressRanges();
65      if (!CURanges)
66        CTX->getRecoverableErrorHandler()(CURanges.takeError());
67      else
68        for (const auto &R : *CURanges)
69          appendRange(CUOffset, R.LowPC, R.HighPC);
70    }
71  }
72
73  construct();
74}
75
76void DWARFDebugAranges::clear() {
77  Endpoints.clear();
78  Aranges.clear();
79  ParsedCUOffsets.clear();
80}
81
82void DWARFDebugAranges::appendRange(uint64_t CUOffset, uint64_t LowPC,
83                                    uint64_t HighPC) {
84  if (LowPC >= HighPC)
85    return;
86  Endpoints.emplace_back(LowPC, CUOffset, true);
87  Endpoints.emplace_back(HighPC, CUOffset, false);
88}
89
90void DWARFDebugAranges::construct() {
91  std::multiset<uint64_t> ValidCUs;  // Maintain the set of CUs describing
92                                     // a current address range.
93  llvm::sort(Endpoints);
94  uint64_t PrevAddress = -1ULL;
95  for (const auto &E : Endpoints) {
96    if (PrevAddress < E.Address && !ValidCUs.empty()) {
97      // If the address range between two endpoints is described by some
98      // CU, first try to extend the last range in Aranges. If we can't
99      // do it, start a new range.
100      if (!Aranges.empty() && Aranges.back().HighPC() == PrevAddress &&
101          ValidCUs.find(Aranges.back().CUOffset) != ValidCUs.end()) {
102        Aranges.back().setHighPC(E.Address);
103      } else {
104        Aranges.emplace_back(PrevAddress, E.Address, *ValidCUs.begin());
105      }
106    }
107    // Update the set of valid CUs.
108    if (E.IsRangeStart) {
109      ValidCUs.insert(E.CUOffset);
110    } else {
111      auto CUPos = ValidCUs.find(E.CUOffset);
112      assert(CUPos != ValidCUs.end());
113      ValidCUs.erase(CUPos);
114    }
115    PrevAddress = E.Address;
116  }
117  assert(ValidCUs.empty());
118
119  // Endpoints are not needed now.
120  Endpoints.clear();
121  Endpoints.shrink_to_fit();
122}
123
124uint64_t DWARFDebugAranges::findAddress(uint64_t Address) const {
125  RangeCollIterator It =
126      partition_point(Aranges, [=](Range R) { return R.HighPC() <= Address; });
127  if (It != Aranges.end() && It->LowPC <= Address)
128    return It->CUOffset;
129  return -1ULL;
130}
131