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
21 using namespace llvm;
22
extract(DataExtractor DebugArangesData)23 void 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
generate(DWARFContext * CTX)40 void DWARFDebugAranges::generate(DWARFContext *CTX) {
41 clear();
42 if (!CTX)
43 return;
44
45 // Extract aranges from .debug_aranges section.
46 DataExtractor ArangesData(CTX->getDWARFObj().getARangeSection(),
47 CTX->isLittleEndian(), 0);
48 extract(ArangesData);
49
50 // Generate aranges from DIEs: even if .debug_aranges section is present,
51 // it may describe only a small subset of compilation units, so we need to
52 // manually build aranges for the rest of them.
53 for (const auto &CU : CTX->compile_units()) {
54 uint32_t CUOffset = CU->getOffset();
55 if (ParsedCUOffsets.insert(CUOffset).second) {
56 DWARFAddressRangesVector CURanges;
57 CU->collectAddressRanges(CURanges);
58 for (const auto &R : CURanges)
59 appendRange(CUOffset, R.LowPC, R.HighPC);
60 }
61 }
62
63 construct();
64 }
65
clear()66 void DWARFDebugAranges::clear() {
67 Endpoints.clear();
68 Aranges.clear();
69 ParsedCUOffsets.clear();
70 }
71
appendRange(uint32_t CUOffset,uint64_t LowPC,uint64_t HighPC)72 void DWARFDebugAranges::appendRange(uint32_t CUOffset, uint64_t LowPC,
73 uint64_t HighPC) {
74 if (LowPC >= HighPC)
75 return;
76 Endpoints.emplace_back(LowPC, CUOffset, true);
77 Endpoints.emplace_back(HighPC, CUOffset, false);
78 }
79
construct()80 void DWARFDebugAranges::construct() {
81 std::multiset<uint32_t> ValidCUs; // Maintain the set of CUs describing
82 // a current address range.
83 llvm::sort(Endpoints.begin(), Endpoints.end());
84 uint64_t PrevAddress = -1ULL;
85 for (const auto &E : Endpoints) {
86 if (PrevAddress < E.Address && !ValidCUs.empty()) {
87 // If the address range between two endpoints is described by some
88 // CU, first try to extend the last range in Aranges. If we can't
89 // do it, start a new range.
90 if (!Aranges.empty() && Aranges.back().HighPC() == PrevAddress &&
91 ValidCUs.find(Aranges.back().CUOffset) != ValidCUs.end()) {
92 Aranges.back().setHighPC(E.Address);
93 } else {
94 Aranges.emplace_back(PrevAddress, E.Address, *ValidCUs.begin());
95 }
96 }
97 // Update the set of valid CUs.
98 if (E.IsRangeStart) {
99 ValidCUs.insert(E.CUOffset);
100 } else {
101 auto CUPos = ValidCUs.find(E.CUOffset);
102 assert(CUPos != ValidCUs.end());
103 ValidCUs.erase(CUPos);
104 }
105 PrevAddress = E.Address;
106 }
107 assert(ValidCUs.empty());
108
109 // Endpoints are not needed now.
110 Endpoints.clear();
111 Endpoints.shrink_to_fit();
112 }
113
findAddress(uint64_t Address) const114 uint32_t DWARFDebugAranges::findAddress(uint64_t Address) const {
115 if (!Aranges.empty()) {
116 Range range(Address);
117 RangeCollIterator begin = Aranges.begin();
118 RangeCollIterator end = Aranges.end();
119 RangeCollIterator pos =
120 std::lower_bound(begin, end, range);
121
122 if (pos != end && pos->containsAddress(Address)) {
123 return pos->CUOffset;
124 } else if (pos != begin) {
125 --pos;
126 if (pos->containsAddress(Address))
127 return pos->CUOffset;
128 }
129 }
130 return -1U;
131 }
132