xref: /llvm-project/llvm/lib/DebugInfo/DWARF/DWARFDebugAranges.cpp (revision 0060c54e0da6d1429875da2d30895faa7562b706)
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 
20 using namespace llvm;
21 
22 void DWARFDebugAranges::extract(
23     DWARFDataExtractor DebugArangesData,
24     function_ref<void(Error)> RecoverableErrorHandler,
25     function_ref<void(Error)> WarningHandler) {
26   if (!DebugArangesData.isValidOffset(0))
27     return;
28   uint64_t Offset = 0;
29   DWARFDebugArangeSet Set;
30 
31   while (DebugArangesData.isValidOffset(Offset)) {
32     if (Error E = Set.extract(DebugArangesData, &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(CUOffset);
43   }
44 }
45 
46 void 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(ArangesData, CTX->getRecoverableErrorHandler(),
55           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(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, R.LowPC, R.HighPC);
69     }
70   }
71 
72   construct();
73 }
74 
75 void DWARFDebugAranges::clear() {
76   Endpoints.clear();
77   Aranges.clear();
78   ParsedCUOffsets.clear();
79 }
80 
81 void DWARFDebugAranges::appendRange(uint64_t CUOffset, uint64_t LowPC,
82                                     uint64_t HighPC) {
83   if (LowPC >= HighPC)
84     return;
85   Endpoints.emplace_back(LowPC, CUOffset, true);
86   Endpoints.emplace_back(HighPC, CUOffset, false);
87 }
88 
89 void DWARFDebugAranges::construct() {
90   std::multiset<uint64_t> ValidCUs;  // Maintain the set of CUs describing
91                                      // a current address range.
92   llvm::sort(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(Aranges.back().CUOffset) != ValidCUs.end()) {
101         Aranges.back().setHighPC(E.Address);
102       } else {
103         Aranges.emplace_back(PrevAddress, E.Address, *ValidCUs.begin());
104       }
105     }
106     // Update the set of valid CUs.
107     if (E.IsRangeStart) {
108       ValidCUs.insert(E.CUOffset);
109     } else {
110       auto CUPos = ValidCUs.find(E.CUOffset);
111       assert(CUPos != ValidCUs.end());
112       ValidCUs.erase(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 
123 uint64_t DWARFDebugAranges::findAddress(uint64_t Address) const {
124   RangeCollIterator It =
125       partition_point(Aranges, [=](Range R) { return R.HighPC() <= Address; });
126   if (It != Aranges.end() && It->LowPC <= Address)
127     return It->CUOffset;
128   return -1ULL;
129 }
130