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