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   size_t CalculateNumChildren() override;
30 
31   lldb::ValueObjectSP GetChildAtIndex(size_t idx) override;
32 
33   bool 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 
56 LibStdcppUniquePtrSyntheticFrontEnd::LibStdcppUniquePtrSyntheticFrontEnd(
57     lldb::ValueObjectSP valobj_sp)
58     : SyntheticChildrenFrontEnd(*valobj_sp) {
59   Update();
60 }
61 
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 =
73       valobj_sp->GetChildMemberWithName(ConstString("_M_t"), true);
74   if (!obj_child_sp)
75       return nullptr;
76 
77   ValueObjectSP obj_subchild_sp =
78       obj_child_sp->GetChildMemberWithName(ConstString("_M_t"), true);
79 
80   // if there is a _M_t subchild, the tuple is found in the obj_subchild_sp
81   // (for libstdc++ 6.0.23).
82   if (obj_subchild_sp) {
83     return obj_subchild_sp;
84   }
85 
86   return obj_child_sp;
87 }
88 
89 bool LibStdcppUniquePtrSyntheticFrontEnd::Update() {
90   ValueObjectSP tuple_sp = GetTuple();
91 
92   if (!tuple_sp)
93     return false;
94 
95   std::unique_ptr<SyntheticChildrenFrontEnd> tuple_frontend(
96       LibStdcppTupleSyntheticFrontEndCreator(nullptr, tuple_sp));
97 
98   ValueObjectSP ptr_obj = tuple_frontend->GetChildAtIndex(0);
99   if (ptr_obj)
100     m_ptr_obj = ptr_obj->Clone(ConstString("pointer")).get();
101 
102   // Add a 'deleter' child if there was a non-empty deleter type specified.
103   //
104   // The object might have size=1 in the TypeSystem but occupies no dedicated
105   // storage due to no_unique_address, so infer the actual size from the total
106   // size of the unique_ptr class. If sizeof(unique_ptr) == sizeof(void*) then
107   // the deleter is empty and should be hidden.
108   if (tuple_sp->GetByteSize() > ptr_obj->GetByteSize()) {
109     ValueObjectSP del_obj = tuple_frontend->GetChildAtIndex(1);
110     if (del_obj)
111       m_del_obj = del_obj->Clone(ConstString("deleter")).get();
112   }
113 
114   if (m_ptr_obj) {
115     Status error;
116     ValueObjectSP obj_obj = m_ptr_obj->Dereference(error);
117     if (error.Success()) {
118       m_obj_obj = obj_obj->Clone(ConstString("object")).get();
119     }
120   }
121 
122   return false;
123 }
124 
125 bool LibStdcppUniquePtrSyntheticFrontEnd::MightHaveChildren() { return true; }
126 
127 lldb::ValueObjectSP
128 LibStdcppUniquePtrSyntheticFrontEnd::GetChildAtIndex(size_t idx) {
129   if (idx == 0 && m_ptr_obj)
130     return m_ptr_obj->GetSP();
131   if (idx == 1 && m_del_obj)
132     return m_del_obj->GetSP();
133   if (idx == 2 && m_obj_obj)
134     return m_obj_obj->GetSP();
135   return lldb::ValueObjectSP();
136 }
137 
138 size_t LibStdcppUniquePtrSyntheticFrontEnd::CalculateNumChildren() {
139   if (m_del_obj)
140     return 2;
141   return 1;
142 }
143 
144 size_t LibStdcppUniquePtrSyntheticFrontEnd::GetIndexOfChildWithName(
145     ConstString name) {
146   if (name == "ptr" || name == "pointer")
147     return 0;
148   if (name == "del" || name == "deleter")
149     return 1;
150   if (name == "obj" || name == "object" || name == "$$dereference$$")
151     return 2;
152   return UINT32_MAX;
153 }
154 
155 bool LibStdcppUniquePtrSyntheticFrontEnd::GetSummary(
156     Stream &stream, const TypeSummaryOptions &options) {
157   if (!m_ptr_obj)
158     return false;
159 
160   bool success;
161   uint64_t ptr_value = m_ptr_obj->GetValueAsUnsigned(0, &success);
162   if (!success)
163     return false;
164   if (ptr_value == 0)
165     stream.Printf("nullptr");
166   else
167     stream.Printf("0x%" PRIx64, ptr_value);
168   return true;
169 }
170 
171 SyntheticChildrenFrontEnd *
172 lldb_private::formatters::LibStdcppUniquePtrSyntheticFrontEndCreator(
173     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
174   return (valobj_sp ? new LibStdcppUniquePtrSyntheticFrontEnd(valobj_sp)
175                     : nullptr);
176 }
177 
178 bool lldb_private::formatters::LibStdcppUniquePointerSummaryProvider(
179     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
180   LibStdcppUniquePtrSyntheticFrontEnd formatter(valobj.GetSP());
181   return formatter.GetSummary(stream, options);
182 }
183