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 "llvm/Support/WithColor.h"
16 #include <algorithm>
17 #include <cassert>
18 #include <cstdint>
19 #include <set>
20 #include <vector>
21
22 using namespace llvm;
23
extract(DataExtractor DebugArangesData)24 void DWARFDebugAranges::extract(DataExtractor DebugArangesData) {
25 if (!DebugArangesData.isValidOffset(0))
26 return;
27 uint32_t Offset = 0;
28 DWARFDebugArangeSet Set;
29
30 while (Set.extract(DebugArangesData, &Offset)) {
31 uint32_t CUOffset = Set.getCompileUnitDIEOffset();
32 for (const auto &Desc : Set.descriptors()) {
33 uint64_t LowPC = Desc.Address;
34 uint64_t HighPC = Desc.getEndAddress();
35 appendRange(CUOffset, LowPC, HighPC);
36 }
37 ParsedCUOffsets.insert(CUOffset);
38 }
39 }
40
generate(DWARFContext * CTX)41 void DWARFDebugAranges::generate(DWARFContext *CTX) {
42 clear();
43 if (!CTX)
44 return;
45
46 // Extract aranges from .debug_aranges section.
47 DataExtractor ArangesData(CTX->getDWARFObj().getARangeSection(),
48 CTX->isLittleEndian(), 0);
49 extract(ArangesData);
50
51 // Generate aranges from DIEs: even if .debug_aranges section is present,
52 // it may describe only a small subset of compilation units, so we need to
53 // manually build aranges for the rest of them.
54 for (const auto &CU : CTX->compile_units()) {
55 uint32_t CUOffset = CU->getOffset();
56 if (ParsedCUOffsets.insert(CUOffset).second) {
57 Expected<DWARFAddressRangesVector> CURanges = CU->collectAddressRanges();
58 if (!CURanges)
59 WithColor::error() << toString(CURanges.takeError()) << '\n';
60 else
61 for (const auto &R : *CURanges)
62 appendRange(CUOffset, R.LowPC, R.HighPC);
63 }
64 }
65
66 construct();
67 }
68
clear()69 void DWARFDebugAranges::clear() {
70 Endpoints.clear();
71 Aranges.clear();
72 ParsedCUOffsets.clear();
73 }
74
appendRange(uint32_t CUOffset,uint64_t LowPC,uint64_t HighPC)75 void DWARFDebugAranges::appendRange(uint32_t CUOffset, uint64_t LowPC,
76 uint64_t HighPC) {
77 if (LowPC >= HighPC)
78 return;
79 Endpoints.emplace_back(LowPC, CUOffset, true);
80 Endpoints.emplace_back(HighPC, CUOffset, false);
81 }
82
construct()83 void DWARFDebugAranges::construct() {
84 std::multiset<uint32_t> ValidCUs; // Maintain the set of CUs describing
85 // a current address range.
86 llvm::sort(Endpoints);
87 uint64_t PrevAddress = -1ULL;
88 for (const auto &E : Endpoints) {
89 if (PrevAddress < E.Address && !ValidCUs.empty()) {
90 // If the address range between two endpoints is described by some
91 // CU, first try to extend the last range in Aranges. If we can't
92 // do it, start a new range.
93 if (!Aranges.empty() && Aranges.back().HighPC() == PrevAddress &&
94 ValidCUs.find(Aranges.back().CUOffset) != ValidCUs.end()) {
95 Aranges.back().setHighPC(E.Address);
96 } else {
97 Aranges.emplace_back(PrevAddress, E.Address, *ValidCUs.begin());
98 }
99 }
100 // Update the set of valid CUs.
101 if (E.IsRangeStart) {
102 ValidCUs.insert(E.CUOffset);
103 } else {
104 auto CUPos = ValidCUs.find(E.CUOffset);
105 assert(CUPos != ValidCUs.end());
106 ValidCUs.erase(CUPos);
107 }
108 PrevAddress = E.Address;
109 }
110 assert(ValidCUs.empty());
111
112 // Endpoints are not needed now.
113 Endpoints.clear();
114 Endpoints.shrink_to_fit();
115 }
116
findAddress(uint64_t Address) const117 uint32_t DWARFDebugAranges::findAddress(uint64_t Address) const {
118 if (!Aranges.empty()) {
119 Range range(Address);
120 RangeCollIterator begin = Aranges.begin();
121 RangeCollIterator end = Aranges.end();
122 RangeCollIterator pos =
123 std::lower_bound(begin, end, range);
124
125 if (pos != end && pos->containsAddress(Address)) {
126 return pos->CUOffset;
127 } else if (pos != begin) {
128 --pos;
129 if (pos->containsAddress(Address))
130 return pos->CUOffset;
131 }
132 }
133 return -1U;
134 }
135