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 "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/Format.h"
15 #include "llvm/Support/raw_ostream.h"
16 #include <algorithm>
17 #include <cassert>
18 #include <set>
19 using namespace llvm;
20
extract(DataExtractor DebugArangesData)21 void 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
generate(DWARFContext * CTX)38 void 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
clear()64 void DWARFDebugAranges::clear() {
65 Endpoints.clear();
66 Aranges.clear();
67 ParsedCUOffsets.clear();
68 }
69
appendRange(uint32_t CUOffset,uint64_t LowPC,uint64_t HighPC)70 void 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
construct()78 void 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
findAddress(uint64_t Address) const112 uint32_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