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