1 //===-- GenericOptional.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 "Generic.h"
10 #include "LibCxx.h"
11 #include "LibStdcpp.h"
12 #include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
13 #include "lldb/DataFormatters/FormattersHelpers.h"
14 #include "lldb/Target/Target.h"
15
16 using namespace lldb;
17 using namespace lldb_private;
18
GenericOptionalSummaryProvider(ValueObject & valobj,Stream & stream,const TypeSummaryOptions & options)19 bool lldb_private::formatters::GenericOptionalSummaryProvider(
20 ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
21 stream.Printf(" Has Value=%s ",
22 valobj.GetNumChildrenIgnoringErrors() == 0 ? "false" : "true");
23
24 return true;
25 }
26
27 // Synthetic Children Provider
28 namespace {
29
30 class GenericOptionalFrontend : public SyntheticChildrenFrontEnd {
31 public:
32 enum class StdLib {
33 LibCxx,
34 LibStdcpp,
35 };
36
37 GenericOptionalFrontend(ValueObject &valobj, StdLib stdlib);
38
GetIndexOfChildWithName(ConstString name)39 llvm::Expected<size_t> GetIndexOfChildWithName(ConstString name) override {
40 if (name == "$$dereference$$")
41 return 0;
42 auto optional_idx = formatters::ExtractIndexFromString(name.GetCString());
43 if (!optional_idx) {
44 return llvm::createStringError("Type has no child named '%s'",
45 name.AsCString());
46 }
47 return *optional_idx;
48 }
49
CalculateNumChildren()50 llvm::Expected<uint32_t> CalculateNumChildren() override {
51 return m_has_value ? 1U : 0U;
52 }
53
54 ValueObjectSP GetChildAtIndex(uint32_t idx) override;
55 lldb::ChildCacheState Update() override;
56
57 private:
58 bool m_has_value = false;
59 StdLib m_stdlib;
60 };
61
62 } // namespace
63
GenericOptionalFrontend(ValueObject & valobj,StdLib stdlib)64 GenericOptionalFrontend::GenericOptionalFrontend(ValueObject &valobj,
65 StdLib stdlib)
66 : SyntheticChildrenFrontEnd(valobj), m_stdlib(stdlib) {
67 if (auto target_sp = m_backend.GetTargetSP()) {
68 Update();
69 }
70 }
71
Update()72 lldb::ChildCacheState GenericOptionalFrontend::Update() {
73 ValueObjectSP engaged_sp;
74
75 if (m_stdlib == StdLib::LibCxx)
76 engaged_sp = m_backend.GetChildMemberWithName("__engaged_");
77 else if (m_stdlib == StdLib::LibStdcpp) {
78 if (ValueObjectSP payload = m_backend.GetChildMemberWithName("_M_payload"))
79 engaged_sp = payload->GetChildMemberWithName("_M_engaged");
80 }
81
82 if (!engaged_sp)
83 return lldb::ChildCacheState::eRefetch;
84
85 // _M_engaged/__engaged is a bool flag and is true if the optional contains a
86 // value. Converting it to unsigned gives us a size of 1 if it contains a
87 // value and 0 if not.
88 m_has_value = engaged_sp->GetValueAsUnsigned(0) != 0;
89
90 return lldb::ChildCacheState::eRefetch;
91 }
92
GetChildAtIndex(uint32_t _idx)93 ValueObjectSP GenericOptionalFrontend::GetChildAtIndex(uint32_t _idx) {
94 if (!m_has_value)
95 return ValueObjectSP();
96
97 ValueObjectSP val_sp;
98
99 if (m_stdlib == StdLib::LibCxx)
100 // __val_ contains the underlying value of an optional if it has one.
101 // Currently because it is part of an anonymous union
102 // GetChildMemberWithName() does not peer through and find it unless we are
103 // at the parent itself. We can obtain the parent through __engaged_.
104 val_sp = m_backend.GetChildMemberWithName("__engaged_")
105 ->GetParent()
106 ->GetChildAtIndex(0)
107 ->GetChildMemberWithName("__val_");
108 else if (m_stdlib == StdLib::LibStdcpp) {
109 val_sp = m_backend.GetChildMemberWithName("_M_payload")
110 ->GetChildMemberWithName("_M_payload");
111
112 // In some implementations, _M_value contains the underlying value of an
113 // optional, and in other versions, it's in the payload member.
114 ValueObjectSP candidate = val_sp->GetChildMemberWithName("_M_value");
115 if (candidate)
116 val_sp = candidate;
117 }
118
119 if (!val_sp)
120 return ValueObjectSP();
121
122 CompilerType holder_type = val_sp->GetCompilerType();
123
124 if (!holder_type)
125 return ValueObjectSP();
126
127 return val_sp->Clone(ConstString("Value"));
128 }
129
130 SyntheticChildrenFrontEnd *
LibStdcppOptionalSyntheticFrontEndCreator(CXXSyntheticChildren *,lldb::ValueObjectSP valobj_sp)131 formatters::LibStdcppOptionalSyntheticFrontEndCreator(
132 CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
133 if (valobj_sp)
134 return new GenericOptionalFrontend(
135 *valobj_sp, GenericOptionalFrontend::StdLib::LibStdcpp);
136 return nullptr;
137 }
138
LibcxxOptionalSyntheticFrontEndCreator(CXXSyntheticChildren *,lldb::ValueObjectSP valobj_sp)139 SyntheticChildrenFrontEnd *formatters::LibcxxOptionalSyntheticFrontEndCreator(
140 CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
141 if (valobj_sp)
142 return new GenericOptionalFrontend(*valobj_sp,
143 GenericOptionalFrontend::StdLib::LibCxx);
144 return nullptr;
145 }
146