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/DWARFCompileUnit.h"
11 #include "llvm/DebugInfo/DWARF/DWARFContext.h"
12 #include "llvm/DebugInfo/DWARF/DWARFDebugArangeSet.h"
13 #include "llvm/Support/DataExtractor.h"
14 #include <algorithm>
15 #include <cassert>
16 #include <cstdint>
17 #include <set>
18 #include <vector>
19
20 using namespace llvm;
21
extract(DWARFDataExtractor DebugArangesData,function_ref<void (Error)> RecoverableErrorHandler)22 void DWARFDebugAranges::extract(
23 DWARFDataExtractor DebugArangesData,
24 function_ref<void(Error)> RecoverableErrorHandler) {
25 if (!DebugArangesData.isValidOffset(0))
26 return;
27 uint64_t Offset = 0;
28 DWARFDebugArangeSet Set;
29
30 while (DebugArangesData.isValidOffset(Offset)) {
31 if (Error E = Set.extract(DebugArangesData, &Offset)) {
32 RecoverableErrorHandler(std::move(E));
33 return;
34 }
35 uint64_t CUOffset = Set.getCompileUnitDIEOffset();
36 for (const auto &Desc : Set.descriptors()) {
37 uint64_t LowPC = Desc.Address;
38 uint64_t HighPC = Desc.getEndAddress();
39 appendRange(CUOffset, LowPC, HighPC);
40 }
41 ParsedCUOffsets.insert(CUOffset);
42 }
43 }
44
generate(DWARFContext * CTX)45 void DWARFDebugAranges::generate(DWARFContext *CTX) {
46 clear();
47 if (!CTX)
48 return;
49
50 // Extract aranges from .debug_aranges section.
51 DWARFDataExtractor ArangesData(CTX->getDWARFObj().getArangesSection(),
52 CTX->isLittleEndian(), 0);
53 extract(ArangesData, CTX->getRecoverableErrorHandler());
54
55 // Generate aranges from DIEs: even if .debug_aranges section is present,
56 // it may describe only a small subset of compilation units, so we need to
57 // manually build aranges for the rest of them.
58 for (const auto &CU : CTX->compile_units()) {
59 uint64_t CUOffset = CU->getOffset();
60 if (ParsedCUOffsets.insert(CUOffset).second) {
61 Expected<DWARFAddressRangesVector> CURanges = CU->collectAddressRanges();
62 if (!CURanges)
63 CTX->getRecoverableErrorHandler()(CURanges.takeError());
64 else
65 for (const auto &R : *CURanges)
66 appendRange(CUOffset, R.LowPC, R.HighPC);
67 }
68 }
69
70 construct();
71 }
72
clear()73 void DWARFDebugAranges::clear() {
74 Endpoints.clear();
75 Aranges.clear();
76 ParsedCUOffsets.clear();
77 }
78
appendRange(uint64_t CUOffset,uint64_t LowPC,uint64_t HighPC)79 void DWARFDebugAranges::appendRange(uint64_t CUOffset, uint64_t LowPC,
80 uint64_t HighPC) {
81 if (LowPC >= HighPC)
82 return;
83 Endpoints.emplace_back(LowPC, CUOffset, true);
84 Endpoints.emplace_back(HighPC, CUOffset, false);
85 }
86
construct()87 void DWARFDebugAranges::construct() {
88 std::multiset<uint64_t> ValidCUs; // Maintain the set of CUs describing
89 // a current address range.
90 llvm::sort(Endpoints);
91 uint64_t PrevAddress = -1ULL;
92 for (const auto &E : Endpoints) {
93 if (PrevAddress < E.Address && !ValidCUs.empty()) {
94 // If the address range between two endpoints is described by some
95 // CU, first try to extend the last range in Aranges. If we can't
96 // do it, start a new range.
97 if (!Aranges.empty() && Aranges.back().HighPC() == PrevAddress &&
98 ValidCUs.find(Aranges.back().CUOffset) != ValidCUs.end()) {
99 Aranges.back().setHighPC(E.Address);
100 } else {
101 Aranges.emplace_back(PrevAddress, E.Address, *ValidCUs.begin());
102 }
103 }
104 // Update the set of valid CUs.
105 if (E.IsRangeStart) {
106 ValidCUs.insert(E.CUOffset);
107 } else {
108 auto CUPos = ValidCUs.find(E.CUOffset);
109 assert(CUPos != ValidCUs.end());
110 ValidCUs.erase(CUPos);
111 }
112 PrevAddress = E.Address;
113 }
114 assert(ValidCUs.empty());
115
116 // Endpoints are not needed now.
117 Endpoints.clear();
118 Endpoints.shrink_to_fit();
119 }
120
findAddress(uint64_t Address) const121 uint64_t DWARFDebugAranges::findAddress(uint64_t Address) const {
122 RangeCollIterator It =
123 partition_point(Aranges, [=](Range R) { return R.HighPC() <= Address; });
124 if (It != Aranges.end() && It->LowPC <= Address)
125 return It->CUOffset;
126 return -1ULL;
127 }
128