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| 1 | +//===-- MsvcStlVariant.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 "MsvcStl.h" |
| 10 | +#include "lldb/DataFormatters/FormattersHelpers.h" |
| 11 | +#include "lldb/Symbol/CompilerType.h" |
| 12 | +#include <optional> |
| 13 | + |
| 14 | +using namespace lldb; |
| 15 | +using namespace lldb_private; |
| 16 | + |
| 17 | +namespace { |
| 18 | + |
| 19 | +// A variant when using DWARF looks as follows: |
| 20 | +// (lldb) fr v -R v1 |
| 21 | +// (std::variant<int, double, char>) v1 = { |
| 22 | +// std::_SMF_control<std::_Variant_base<int, double, char>, int, double, char> |
| 23 | +// = { |
| 24 | +// std::_Variant_storage<int, double, char> = { |
| 25 | +// = { |
| 26 | +// _Head = 0 |
| 27 | +// _Tail = { |
| 28 | +// = { |
| 29 | +// _Head = 2 |
| 30 | +// _Tail = { |
| 31 | +// = { |
| 32 | +// _Head = '\0' |
| 33 | +// _Tail = {} |
| 34 | +// } |
| 35 | +// } |
| 36 | +// } |
| 37 | +// } |
| 38 | +// } |
| 39 | +// } |
| 40 | +// _Which = '\x01' |
| 41 | +// } |
| 42 | +// } |
| 43 | + |
| 44 | +ValueObjectSP GetStorageMember(ValueObject &valobj, llvm::StringRef name) { |
| 45 | + // Find the union |
| 46 | + ValueObjectSP union_sp = valobj.GetChildAtIndex(0); |
| 47 | + if (!union_sp) |
| 48 | + return nullptr; |
| 49 | + return union_sp->GetChildMemberWithName(name); |
| 50 | +} |
| 51 | + |
| 52 | +ValueObjectSP GetHead(ValueObject &valobj) { |
| 53 | + return GetStorageMember(valobj, "_Head"); |
| 54 | +} |
| 55 | +ValueObjectSP GetTail(ValueObject &valobj) { |
| 56 | + return GetStorageMember(valobj, "_Tail"); |
| 57 | +} |
| 58 | + |
| 59 | +std::optional<int64_t> GetIndexValue(ValueObject &valobj) { |
| 60 | + ValueObjectSP index_sp = valobj.GetChildMemberWithName("_Which"); |
| 61 | + if (!index_sp) |
| 62 | + return std::nullopt; |
| 63 | + |
| 64 | + return {index_sp->GetValueAsSigned(-1)}; |
| 65 | +} |
| 66 | + |
| 67 | +ValueObjectSP GetNthStorage(ValueObject &outer, int64_t index) { |
| 68 | + // We need to find the std::_Variant_storage base class. |
| 69 | + |
| 70 | + // -> std::_SMF_control (typedef to std::_Variant_base) |
| 71 | + ValueObjectSP container_sp = outer.GetSP()->GetChildAtIndex(0); |
| 72 | + if (!container_sp) |
| 73 | + return nullptr; |
| 74 | + // -> std::_Variant_storage |
| 75 | + container_sp = container_sp->GetChildAtIndex(0); |
| 76 | + if (!container_sp) |
| 77 | + return nullptr; |
| 78 | + |
| 79 | + for (int64_t i = 0; i < index; i++) { |
| 80 | + container_sp = GetTail(*container_sp); |
| 81 | + if (!container_sp) |
| 82 | + return nullptr; |
| 83 | + } |
| 84 | + return container_sp; |
| 85 | +} |
| 86 | + |
| 87 | +} // namespace |
| 88 | + |
| 89 | +bool formatters::IsMsvcStlVariant(ValueObject &valobj) { |
| 90 | + if (auto valobj_sp = valobj.GetNonSyntheticValue()) { |
| 91 | + return valobj_sp->GetChildMemberWithName("_Which") != nullptr; |
| 92 | + } |
| 93 | + return false; |
| 94 | +} |
| 95 | + |
| 96 | +bool formatters::MsvcStlVariantSummaryProvider( |
| 97 | + ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) { |
| 98 | + ValueObjectSP valobj_sp(valobj.GetNonSyntheticValue()); |
| 99 | + if (!valobj_sp) |
| 100 | + return false; |
| 101 | + |
| 102 | + auto index = GetIndexValue(*valobj_sp); |
| 103 | + if (!index) |
| 104 | + return false; |
| 105 | + |
| 106 | + if (*index < 0) { |
| 107 | + stream.Printf(" No Value"); |
| 108 | + return true; |
| 109 | + } |
| 110 | + |
| 111 | + ValueObjectSP storage = GetNthStorage(*valobj_sp, *index); |
| 112 | + if (!storage) |
| 113 | + return false; |
| 114 | + CompilerType storage_type = storage->GetCompilerType(); |
| 115 | + if (!storage_type) |
| 116 | + return false; |
| 117 | + // Resolve the typedef |
| 118 | + if (storage_type.IsTypedefType()) |
| 119 | + storage_type = storage_type.GetTypedefedType(); |
| 120 | + |
| 121 | + CompilerType active_type = storage_type.GetTypeTemplateArgument(1, true); |
| 122 | + if (!active_type) |
| 123 | + return false; |
| 124 | + |
| 125 | + stream << " Active Type = " << active_type.GetDisplayTypeName() << " "; |
| 126 | + return true; |
| 127 | +} |
| 128 | + |
| 129 | +namespace { |
| 130 | +class VariantFrontEnd : public SyntheticChildrenFrontEnd { |
| 131 | +public: |
| 132 | + VariantFrontEnd(ValueObject &valobj) : SyntheticChildrenFrontEnd(valobj) { |
| 133 | + Update(); |
| 134 | + } |
| 135 | + |
| 136 | + llvm::Expected<size_t> GetIndexOfChildWithName(ConstString name) override { |
| 137 | + auto optional_idx = formatters::ExtractIndexFromString(name.GetCString()); |
| 138 | + if (!optional_idx) { |
| 139 | + return llvm::createStringError("Type has no child named '%s'", |
| 140 | + name.AsCString()); |
| 141 | + } |
| 142 | + return *optional_idx; |
| 143 | + } |
| 144 | + |
| 145 | + lldb::ChildCacheState Update() override; |
| 146 | + llvm::Expected<uint32_t> CalculateNumChildren() override { return m_size; } |
| 147 | + ValueObjectSP GetChildAtIndex(uint32_t idx) override; |
| 148 | + |
| 149 | +private: |
| 150 | + size_t m_size = 0; |
| 151 | +}; |
| 152 | +} // namespace |
| 153 | + |
| 154 | +lldb::ChildCacheState VariantFrontEnd::Update() { |
| 155 | + m_size = 0; |
| 156 | + |
| 157 | + auto index = GetIndexValue(m_backend); |
| 158 | + if (index && *index >= 0) |
| 159 | + m_size = 1; |
| 160 | + |
| 161 | + return lldb::ChildCacheState::eRefetch; |
| 162 | +} |
| 163 | + |
| 164 | +ValueObjectSP VariantFrontEnd::GetChildAtIndex(uint32_t idx) { |
| 165 | + if (idx >= m_size) |
| 166 | + return nullptr; |
| 167 | + |
| 168 | + auto index = GetIndexValue(m_backend); |
| 169 | + if (!index) |
| 170 | + return nullptr; |
| 171 | + |
| 172 | + ValueObjectSP storage_sp = GetNthStorage(m_backend, *index); |
| 173 | + if (!storage_sp) |
| 174 | + return nullptr; |
| 175 | + |
| 176 | + ValueObjectSP head_sp = GetHead(*storage_sp); |
| 177 | + if (!head_sp) |
| 178 | + return nullptr; |
| 179 | + |
| 180 | + return head_sp->Clone(ConstString("Value")); |
| 181 | +} |
| 182 | + |
| 183 | +SyntheticChildrenFrontEnd *formatters::MsvcStlVariantSyntheticFrontEndCreator( |
| 184 | + CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) { |
| 185 | + if (valobj_sp) |
| 186 | + return new VariantFrontEnd(*valobj_sp); |
| 187 | + return nullptr; |
| 188 | +} |
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