1 //===-- LibCxxAtomic.cpp ------------------------------------------*- C++
2 //-*-===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "LibCxxAtomic.h"
11 
12 using namespace lldb;
13 using namespace lldb_private;
14 using namespace lldb_private::formatters;
15 
16 //
17 // We are supporting two versions of libc++ std::atomic
18 //
19 // Given std::atomic<int> i;
20 //
21 // The previous version of std::atomic was laid out like this
22 //
23 // (lldb) frame var -L -R i
24 // 0x00007ffeefbff9a0: (std::__1::atomic<int>) i = {
25 // 0x00007ffeefbff9a0:   std::__1::__atomic_base<int, true> = {
26 // 0x00007ffeefbff9a0:     std::__1::__atomic_base<int, false> = {
27 // 0x00007ffeefbff9a0:       __a_ = 5
28 //        }
29 //    }
30 // }
31 //
32 // In this case we need to obtain __a_ and the current version is laid out as so
33 //
34 // (lldb) frame var -L -R i
35 // 0x00007ffeefbff9b0: (std::__1::atomic<int>) i = {
36 // 0x00007ffeefbff9b0:   std::__1::__atomic_base<int, true> = {
37 // 0x00007ffeefbff9b0:     std::__1::__atomic_base<int, false> = {
38 // 0x00007ffeefbff9b0:       __a_ = {
39 // 0x00007ffeefbff9b0:         std::__1::__cxx_atomic_base_impl<int> = {
40 // 0x00007ffeefbff9b0:           __a_value = 5
41 //                }
42 //          }
43 //       }
44 //    }
45 //}
46 //
47 // In this case we need to obtain __a_value
48 //
49 // The below method covers both cases and returns the relevant member as a
50 // ValueObjectSP
51 //
52 ValueObjectSP
53 lldb_private::formatters::GetLibCxxAtomicValue(ValueObject &valobj) {
54   ValueObjectSP non_sythetic = valobj.GetNonSyntheticValue();
55   if (!non_sythetic)
56     return {};
57 
58   ValueObjectSP member__a_ =
59       non_sythetic->GetChildMemberWithName(ConstString("__a_"), true);
60   if (!member__a_)
61     return {};
62 
63   ValueObjectSP member__a_value =
64       member__a_->GetChildMemberWithName(ConstString("__a_value"), true);
65   if (!member__a_value)
66     return member__a_;
67 
68   return member__a_value;
69 }
70 
71 bool lldb_private::formatters::LibCxxAtomicSummaryProvider(
72     ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
73 
74   if (ValueObjectSP atomic_value = GetLibCxxAtomicValue(valobj)) {
75     std::string summary;
76     if (atomic_value->GetSummaryAsCString(summary, options) &&
77         summary.size() > 0) {
78       stream.Printf("%s", summary.c_str());
79       return true;
80     }
81   }
82 
83   return false;
84 }
85 
86 namespace lldb_private {
87 namespace formatters {
88 class LibcxxStdAtomicSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
89 public:
90   LibcxxStdAtomicSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);
91 
92   ~LibcxxStdAtomicSyntheticFrontEnd() override = default;
93 
94   size_t CalculateNumChildren() override;
95 
96   lldb::ValueObjectSP GetChildAtIndex(size_t idx) override;
97 
98   bool Update() override;
99 
100   bool MightHaveChildren() override;
101 
102   size_t GetIndexOfChildWithName(ConstString name) override;
103 
104   lldb::ValueObjectSP GetSyntheticValue() override;
105 
106 private:
107   ValueObject *m_real_child;
108 };
109 } // namespace formatters
110 } // namespace lldb_private
111 
112 lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::
113     LibcxxStdAtomicSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
114     : SyntheticChildrenFrontEnd(*valobj_sp), m_real_child(nullptr) {}
115 
116 bool lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::Update() {
117   ValueObjectSP atomic_value = GetLibCxxAtomicValue(m_backend);
118   if (atomic_value)
119     m_real_child = GetLibCxxAtomicValue(m_backend).get();
120 
121   return false;
122 }
123 
124 bool lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::
125     MightHaveChildren() {
126   return true;
127 }
128 
129 size_t lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::
130     CalculateNumChildren() {
131   return m_real_child ? m_real_child->GetNumChildren() : 0;
132 }
133 
134 lldb::ValueObjectSP
135 lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::GetChildAtIndex(
136     size_t idx) {
137   return m_real_child ? m_real_child->GetChildAtIndex(idx, true) : nullptr;
138 }
139 
140 size_t lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::
141     GetIndexOfChildWithName(ConstString name) {
142   return m_real_child ? m_real_child->GetIndexOfChildWithName(name)
143                       : UINT32_MAX;
144 }
145 
146 lldb::ValueObjectSP lldb_private::formatters::LibcxxStdAtomicSyntheticFrontEnd::
147     GetSyntheticValue() {
148   if (m_real_child && m_real_child->CanProvideValue())
149     return m_real_child->GetSP();
150   return nullptr;
151 }
152 
153 SyntheticChildrenFrontEnd *
154 lldb_private::formatters::LibcxxAtomicSyntheticFrontEndCreator(
155     CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
156   if (valobj_sp)
157     return new LibcxxStdAtomicSyntheticFrontEnd(valobj_sp);
158   return nullptr;
159 }
160