1 //===-- GenericBitset.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 "LibCxx.h"
10 #include "LibStdcpp.h"
11 #include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
12 #include "lldb/DataFormatters/FormattersHelpers.h"
13 #include "lldb/Target/Target.h"
14 #include <optional>
15
16 using namespace lldb;
17 using namespace lldb_private;
18
19 namespace {
20
21 /// This class can be used for handling bitsets from both libcxx and libstdcpp.
22 class GenericBitsetFrontEnd : public SyntheticChildrenFrontEnd {
23 public:
24 enum class StdLib {
25 LibCxx,
26 LibStdcpp,
27 };
28
29 GenericBitsetFrontEnd(ValueObject &valobj, StdLib stdlib);
30
GetIndexOfChildWithName(ConstString name)31 size_t GetIndexOfChildWithName(ConstString name) override {
32 return formatters::ExtractIndexFromString(name.GetCString());
33 }
34
MightHaveChildren()35 bool MightHaveChildren() override { return true; }
36 lldb::ChildCacheState Update() override;
CalculateNumChildren()37 llvm::Expected<uint32_t> CalculateNumChildren() override {
38 return m_elements.size();
39 }
40 ValueObjectSP GetChildAtIndex(uint32_t idx) override;
41
42 private:
43 llvm::StringRef GetDataContainerMemberName();
44
45 // The lifetime of a ValueObject and all its derivative ValueObjects
46 // (children, clones, etc.) is managed by a ClusterManager. These
47 // objects are only destroyed when every shared pointer to any of them
48 // is destroyed, so we must not store a shared pointer to any ValueObject
49 // derived from our backend ValueObject (since we're in the same cluster).
50 // Value objects created from raw data (i.e. in a different cluster) must
51 // be referenced via shared pointer to keep them alive, however.
52 std::vector<ValueObjectSP> m_elements;
53 ValueObject *m_first = nullptr;
54 CompilerType m_bool_type;
55 ByteOrder m_byte_order = eByteOrderInvalid;
56 uint8_t m_byte_size = 0;
57 StdLib m_stdlib;
58 };
59 } // namespace
60
GenericBitsetFrontEnd(ValueObject & valobj,StdLib stdlib)61 GenericBitsetFrontEnd::GenericBitsetFrontEnd(ValueObject &valobj, StdLib stdlib)
62 : SyntheticChildrenFrontEnd(valobj), m_stdlib(stdlib) {
63 m_bool_type = valobj.GetCompilerType().GetBasicTypeFromAST(eBasicTypeBool);
64 if (auto target_sp = m_backend.GetTargetSP()) {
65 m_byte_order = target_sp->GetArchitecture().GetByteOrder();
66 m_byte_size = target_sp->GetArchitecture().GetAddressByteSize();
67 Update();
68 }
69 }
70
GetDataContainerMemberName()71 llvm::StringRef GenericBitsetFrontEnd::GetDataContainerMemberName() {
72 static constexpr llvm::StringLiteral s_libcxx_case("__first_");
73 static constexpr llvm::StringLiteral s_libstdcpp_case("_M_w");
74 switch (m_stdlib) {
75 case StdLib::LibCxx:
76 return s_libcxx_case;
77 case StdLib::LibStdcpp:
78 return s_libstdcpp_case;
79 }
80 llvm_unreachable("Unknown StdLib enum");
81 }
82
Update()83 lldb::ChildCacheState GenericBitsetFrontEnd::Update() {
84 m_elements.clear();
85 m_first = nullptr;
86
87 TargetSP target_sp = m_backend.GetTargetSP();
88 if (!target_sp)
89 return lldb::ChildCacheState::eRefetch;
90
91 size_t size = 0;
92
93 if (auto arg = m_backend.GetCompilerType().GetIntegralTemplateArgument(0))
94 size = arg->value.getLimitedValue();
95
96 m_elements.assign(size, ValueObjectSP());
97 m_first =
98 m_backend.GetChildMemberWithName(GetDataContainerMemberName()).get();
99 return lldb::ChildCacheState::eRefetch;
100 }
101
GetChildAtIndex(uint32_t idx)102 ValueObjectSP GenericBitsetFrontEnd::GetChildAtIndex(uint32_t idx) {
103 if (idx >= m_elements.size() || !m_first)
104 return ValueObjectSP();
105
106 if (m_elements[idx])
107 return m_elements[idx];
108
109 ExecutionContext ctx = m_backend.GetExecutionContextRef().Lock(false);
110 CompilerType type;
111 ValueObjectSP chunk;
112 // For small bitsets __first_ is not an array, but a plain size_t.
113 if (m_first->GetCompilerType().IsArrayType(&type)) {
114 std::optional<uint64_t> bit_size =
115 type.GetBitSize(ctx.GetBestExecutionContextScope());
116 if (!bit_size || *bit_size == 0)
117 return {};
118 chunk = m_first->GetChildAtIndex(idx / *bit_size);
119 } else {
120 type = m_first->GetCompilerType();
121 chunk = m_first->GetSP();
122 }
123 if (!type || !chunk)
124 return {};
125
126 std::optional<uint64_t> bit_size =
127 type.GetBitSize(ctx.GetBestExecutionContextScope());
128 if (!bit_size || *bit_size == 0)
129 return {};
130 size_t chunk_idx = idx % *bit_size;
131 uint8_t value = !!(chunk->GetValueAsUnsigned(0) & (uint64_t(1) << chunk_idx));
132 DataExtractor data(&value, sizeof(value), m_byte_order, m_byte_size);
133
134 m_elements[idx] = CreateValueObjectFromData(llvm::formatv("[{0}]", idx).str(),
135 data, ctx, m_bool_type);
136
137 return m_elements[idx];
138 }
139
LibStdcppBitsetSyntheticFrontEndCreator(CXXSyntheticChildren *,lldb::ValueObjectSP valobj_sp)140 SyntheticChildrenFrontEnd *formatters::LibStdcppBitsetSyntheticFrontEndCreator(
141 CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
142 if (valobj_sp)
143 return new GenericBitsetFrontEnd(*valobj_sp,
144 GenericBitsetFrontEnd::StdLib::LibStdcpp);
145 return nullptr;
146 }
147
LibcxxBitsetSyntheticFrontEndCreator(CXXSyntheticChildren *,lldb::ValueObjectSP valobj_sp)148 SyntheticChildrenFrontEnd *formatters::LibcxxBitsetSyntheticFrontEndCreator(
149 CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
150 if (valobj_sp)
151 return new GenericBitsetFrontEnd(*valobj_sp,
152 GenericBitsetFrontEnd::StdLib::LibCxx);
153 return nullptr;
154 }
155