1 //===-- LibStdcppUniquePointer.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 "LibStdcpp.h"
10
11 #include "lldb/Core/ValueObject.h"
12 #include "lldb/DataFormatters/FormattersHelpers.h"
13 #include "lldb/DataFormatters/TypeSynthetic.h"
14 #include "lldb/Utility/ConstString.h"
15
16 #include <memory>
17 #include <vector>
18
19 using namespace lldb;
20 using namespace lldb_private;
21 using namespace lldb_private::formatters;
22
23 namespace {
24
25 class LibStdcppUniquePtrSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
26 public:
27 explicit LibStdcppUniquePtrSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);
28
29 llvm::Expected<uint32_t> CalculateNumChildren() override;
30
31 lldb::ValueObjectSP GetChildAtIndex(uint32_t idx) override;
32
33 lldb::ChildCacheState Update() override;
34
35 bool MightHaveChildren() override;
36
37 size_t GetIndexOfChildWithName(ConstString name) override;
38
39 bool GetSummary(Stream &stream, const TypeSummaryOptions &options);
40
41 private:
42 // The lifetime of a ValueObject and all its derivative ValueObjects
43 // (children, clones, etc.) is managed by a ClusterManager. These
44 // objects are only destroyed when every shared pointer to any of them
45 // is destroyed, so we must not store a shared pointer to any ValueObject
46 // derived from our backend ValueObject (since we're in the same cluster).
47 ValueObject* m_ptr_obj = nullptr;
48 ValueObject* m_obj_obj = nullptr;
49 ValueObject* m_del_obj = nullptr;
50
51 ValueObjectSP GetTuple();
52 };
53
54 } // end of anonymous namespace
55
LibStdcppUniquePtrSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)56 LibStdcppUniquePtrSyntheticFrontEnd::LibStdcppUniquePtrSyntheticFrontEnd(
57 lldb::ValueObjectSP valobj_sp)
58 : SyntheticChildrenFrontEnd(*valobj_sp) {
59 Update();
60 }
61
GetTuple()62 ValueObjectSP LibStdcppUniquePtrSyntheticFrontEnd::GetTuple() {
63 ValueObjectSP valobj_backend_sp = m_backend.GetSP();
64
65 if (!valobj_backend_sp)
66 return nullptr;
67
68 ValueObjectSP valobj_sp = valobj_backend_sp->GetNonSyntheticValue();
69 if (!valobj_sp)
70 return nullptr;
71
72 ValueObjectSP obj_child_sp = valobj_sp->GetChildMemberWithName("_M_t");
73 if (!obj_child_sp)
74 return nullptr;
75
76 ValueObjectSP obj_subchild_sp = obj_child_sp->GetChildMemberWithName("_M_t");
77
78 // if there is a _M_t subchild, the tuple is found in the obj_subchild_sp
79 // (for libstdc++ 6.0.23).
80 if (obj_subchild_sp) {
81 return obj_subchild_sp;
82 }
83
84 return obj_child_sp;
85 }
86
Update()87 lldb::ChildCacheState LibStdcppUniquePtrSyntheticFrontEnd::Update() {
88 ValueObjectSP tuple_sp = GetTuple();
89
90 if (!tuple_sp)
91 return lldb::ChildCacheState::eRefetch;
92
93 std::unique_ptr<SyntheticChildrenFrontEnd> tuple_frontend(
94 LibStdcppTupleSyntheticFrontEndCreator(nullptr, tuple_sp));
95
96 ValueObjectSP ptr_obj = tuple_frontend->GetChildAtIndex(0);
97 if (ptr_obj)
98 m_ptr_obj = ptr_obj->Clone(ConstString("pointer")).get();
99
100 // Add a 'deleter' child if there was a non-empty deleter type specified.
101 //
102 // The object might have size=1 in the TypeSystem but occupies no dedicated
103 // storage due to no_unique_address, so infer the actual size from the total
104 // size of the unique_ptr class. If sizeof(unique_ptr) == sizeof(void*) then
105 // the deleter is empty and should be hidden.
106 if (tuple_sp->GetByteSize() > ptr_obj->GetByteSize()) {
107 ValueObjectSP del_obj = tuple_frontend->GetChildAtIndex(1);
108 if (del_obj)
109 m_del_obj = del_obj->Clone(ConstString("deleter")).get();
110 }
111 m_obj_obj = nullptr;
112
113 return lldb::ChildCacheState::eRefetch;
114 }
115
MightHaveChildren()116 bool LibStdcppUniquePtrSyntheticFrontEnd::MightHaveChildren() { return true; }
117
118 lldb::ValueObjectSP
GetChildAtIndex(uint32_t idx)119 LibStdcppUniquePtrSyntheticFrontEnd::GetChildAtIndex(uint32_t idx) {
120 if (idx == 0 && m_ptr_obj)
121 return m_ptr_obj->GetSP();
122 if (idx == 1 && m_del_obj)
123 return m_del_obj->GetSP();
124 if (idx == 2) {
125 if (m_ptr_obj && !m_obj_obj) {
126 Status error;
127 ValueObjectSP obj_obj = m_ptr_obj->Dereference(error);
128 if (error.Success()) {
129 m_obj_obj = obj_obj->Clone(ConstString("object")).get();
130 }
131 }
132 if (m_obj_obj)
133 return m_obj_obj->GetSP();
134 }
135 return lldb::ValueObjectSP();
136 }
137
138 llvm::Expected<uint32_t>
CalculateNumChildren()139 LibStdcppUniquePtrSyntheticFrontEnd::CalculateNumChildren() {
140 if (m_del_obj)
141 return 2;
142 return 1;
143 }
144
GetIndexOfChildWithName(ConstString name)145 size_t LibStdcppUniquePtrSyntheticFrontEnd::GetIndexOfChildWithName(
146 ConstString name) {
147 if (name == "ptr" || name == "pointer")
148 return 0;
149 if (name == "del" || name == "deleter")
150 return 1;
151 if (name == "obj" || name == "object" || name == "$$dereference$$")
152 return 2;
153 return UINT32_MAX;
154 }
155
GetSummary(Stream & stream,const TypeSummaryOptions & options)156 bool LibStdcppUniquePtrSyntheticFrontEnd::GetSummary(
157 Stream &stream, const TypeSummaryOptions &options) {
158 if (!m_ptr_obj)
159 return false;
160
161 bool success;
162 uint64_t ptr_value = m_ptr_obj->GetValueAsUnsigned(0, &success);
163 if (!success)
164 return false;
165 if (ptr_value == 0)
166 stream.Printf("nullptr");
167 else
168 stream.Printf("0x%" PRIx64, ptr_value);
169 return true;
170 }
171
172 SyntheticChildrenFrontEnd *
LibStdcppUniquePtrSyntheticFrontEndCreator(CXXSyntheticChildren *,lldb::ValueObjectSP valobj_sp)173 lldb_private::formatters::LibStdcppUniquePtrSyntheticFrontEndCreator(
174 CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
175 return (valobj_sp ? new LibStdcppUniquePtrSyntheticFrontEnd(valobj_sp)
176 : nullptr);
177 }
178
LibStdcppUniquePointerSummaryProvider(ValueObject & valobj,Stream & stream,const TypeSummaryOptions & options)179 bool lldb_private::formatters::LibStdcppUniquePointerSummaryProvider(
180 ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
181 LibStdcppUniquePtrSyntheticFrontEnd formatter(valobj.GetSP());
182 return formatter.GetSummary(stream, options);
183 }
184