1*f6aab3d8Srobert //===-- LibCxxSpan.cpp ----------------------------------------------------===//
2*f6aab3d8Srobert //
3*f6aab3d8Srobert // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*f6aab3d8Srobert // See https://llvm.org/LICENSE.txt for license information.
5*f6aab3d8Srobert // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*f6aab3d8Srobert //
7*f6aab3d8Srobert //===----------------------------------------------------------------------===//
8*f6aab3d8Srobert
9*f6aab3d8Srobert #include "LibCxx.h"
10*f6aab3d8Srobert
11*f6aab3d8Srobert #include "lldb/Core/ValueObject.h"
12*f6aab3d8Srobert #include "lldb/DataFormatters/FormattersHelpers.h"
13*f6aab3d8Srobert #include "lldb/Utility/ConstString.h"
14*f6aab3d8Srobert #include "llvm/ADT/APSInt.h"
15*f6aab3d8Srobert #include <optional>
16*f6aab3d8Srobert
17*f6aab3d8Srobert using namespace lldb;
18*f6aab3d8Srobert using namespace lldb_private;
19*f6aab3d8Srobert using namespace lldb_private::formatters;
20*f6aab3d8Srobert
21*f6aab3d8Srobert namespace lldb_private {
22*f6aab3d8Srobert namespace formatters {
23*f6aab3d8Srobert
24*f6aab3d8Srobert class LibcxxStdSpanSyntheticFrontEnd : public SyntheticChildrenFrontEnd {
25*f6aab3d8Srobert public:
26*f6aab3d8Srobert LibcxxStdSpanSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);
27*f6aab3d8Srobert
28*f6aab3d8Srobert ~LibcxxStdSpanSyntheticFrontEnd() override = default;
29*f6aab3d8Srobert
30*f6aab3d8Srobert size_t CalculateNumChildren() override;
31*f6aab3d8Srobert
32*f6aab3d8Srobert lldb::ValueObjectSP GetChildAtIndex(size_t idx) override;
33*f6aab3d8Srobert
34*f6aab3d8Srobert /// Determines properties of the std::span<> associated with this object
35*f6aab3d8Srobert //
36*f6aab3d8Srobert // std::span can either be instantiated with a compile-time known
37*f6aab3d8Srobert // extent or a std::dynamic_extent (this is the default if only the
38*f6aab3d8Srobert // type template argument is provided). The layout of std::span
39*f6aab3d8Srobert // depends on whether the extent is dynamic or not. For static
40*f6aab3d8Srobert // extents (e.g., std::span<int, 9>):
41*f6aab3d8Srobert //
42*f6aab3d8Srobert // (std::__1::span<const int, 9>) s = {
43*f6aab3d8Srobert // __data = 0x000000016fdff494
44*f6aab3d8Srobert // }
45*f6aab3d8Srobert //
46*f6aab3d8Srobert // For dynamic extents, e.g., std::span<int>, the layout is:
47*f6aab3d8Srobert //
48*f6aab3d8Srobert // (std::__1::span<const int, 18446744073709551615>) s = {
49*f6aab3d8Srobert // __data = 0x000000016fdff494
50*f6aab3d8Srobert // __size = 6
51*f6aab3d8Srobert // }
52*f6aab3d8Srobert //
53*f6aab3d8Srobert // This function checks for a '__size' member to determine the number
54*f6aab3d8Srobert // of elements in the span. If no such member exists, we get the size
55*f6aab3d8Srobert // from the only other place it can be: the template argument.
56*f6aab3d8Srobert bool Update() override;
57*f6aab3d8Srobert
58*f6aab3d8Srobert bool MightHaveChildren() override;
59*f6aab3d8Srobert
60*f6aab3d8Srobert size_t GetIndexOfChildWithName(ConstString name) override;
61*f6aab3d8Srobert
62*f6aab3d8Srobert private:
63*f6aab3d8Srobert ValueObject *m_start = nullptr; ///< First element of span. Held, not owned.
64*f6aab3d8Srobert CompilerType m_element_type{}; ///< Type of span elements.
65*f6aab3d8Srobert size_t m_num_elements = 0; ///< Number of elements in span.
66*f6aab3d8Srobert uint32_t m_element_size = 0; ///< Size in bytes of each span element.
67*f6aab3d8Srobert };
68*f6aab3d8Srobert
69*f6aab3d8Srobert lldb_private::formatters::LibcxxStdSpanSyntheticFrontEnd::
LibcxxStdSpanSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)70*f6aab3d8Srobert LibcxxStdSpanSyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
71*f6aab3d8Srobert : SyntheticChildrenFrontEnd(*valobj_sp) {
72*f6aab3d8Srobert if (valobj_sp)
73*f6aab3d8Srobert Update();
74*f6aab3d8Srobert }
75*f6aab3d8Srobert
76*f6aab3d8Srobert size_t lldb_private::formatters::LibcxxStdSpanSyntheticFrontEnd::
CalculateNumChildren()77*f6aab3d8Srobert CalculateNumChildren() {
78*f6aab3d8Srobert return m_num_elements;
79*f6aab3d8Srobert }
80*f6aab3d8Srobert
81*f6aab3d8Srobert lldb::ValueObjectSP
GetChildAtIndex(size_t idx)82*f6aab3d8Srobert lldb_private::formatters::LibcxxStdSpanSyntheticFrontEnd::GetChildAtIndex(
83*f6aab3d8Srobert size_t idx) {
84*f6aab3d8Srobert if (!m_start)
85*f6aab3d8Srobert return {};
86*f6aab3d8Srobert
87*f6aab3d8Srobert uint64_t offset = idx * m_element_size;
88*f6aab3d8Srobert offset = offset + m_start->GetValueAsUnsigned(0);
89*f6aab3d8Srobert StreamString name;
90*f6aab3d8Srobert name.Printf("[%" PRIu64 "]", (uint64_t)idx);
91*f6aab3d8Srobert return CreateValueObjectFromAddress(name.GetString(), offset,
92*f6aab3d8Srobert m_backend.GetExecutionContextRef(),
93*f6aab3d8Srobert m_element_type);
94*f6aab3d8Srobert }
95*f6aab3d8Srobert
Update()96*f6aab3d8Srobert bool lldb_private::formatters::LibcxxStdSpanSyntheticFrontEnd::Update() {
97*f6aab3d8Srobert // Get element type.
98*f6aab3d8Srobert ValueObjectSP data_type_finder_sp = GetChildMemberWithName(
99*f6aab3d8Srobert m_backend, {ConstString("__data_"), ConstString("__data")});
100*f6aab3d8Srobert if (!data_type_finder_sp)
101*f6aab3d8Srobert return false;
102*f6aab3d8Srobert
103*f6aab3d8Srobert m_element_type = data_type_finder_sp->GetCompilerType().GetPointeeType();
104*f6aab3d8Srobert
105*f6aab3d8Srobert // Get element size.
106*f6aab3d8Srobert if (std::optional<uint64_t> size = m_element_type.GetByteSize(nullptr)) {
107*f6aab3d8Srobert m_element_size = *size;
108*f6aab3d8Srobert
109*f6aab3d8Srobert // Get data.
110*f6aab3d8Srobert if (m_element_size > 0) {
111*f6aab3d8Srobert m_start = data_type_finder_sp.get();
112*f6aab3d8Srobert }
113*f6aab3d8Srobert
114*f6aab3d8Srobert // Get number of elements.
115*f6aab3d8Srobert if (auto size_sp = GetChildMemberWithName(
116*f6aab3d8Srobert m_backend, {ConstString("__size_"), ConstString("__size")})) {
117*f6aab3d8Srobert m_num_elements = size_sp->GetValueAsUnsigned(0);
118*f6aab3d8Srobert } else if (auto arg =
119*f6aab3d8Srobert m_backend.GetCompilerType().GetIntegralTemplateArgument(1)) {
120*f6aab3d8Srobert
121*f6aab3d8Srobert m_num_elements = arg->value.getLimitedValue();
122*f6aab3d8Srobert }
123*f6aab3d8Srobert }
124*f6aab3d8Srobert
125*f6aab3d8Srobert return true;
126*f6aab3d8Srobert }
127*f6aab3d8Srobert
128*f6aab3d8Srobert bool lldb_private::formatters::LibcxxStdSpanSyntheticFrontEnd::
MightHaveChildren()129*f6aab3d8Srobert MightHaveChildren() {
130*f6aab3d8Srobert return true;
131*f6aab3d8Srobert }
132*f6aab3d8Srobert
133*f6aab3d8Srobert size_t lldb_private::formatters::LibcxxStdSpanSyntheticFrontEnd::
GetIndexOfChildWithName(ConstString name)134*f6aab3d8Srobert GetIndexOfChildWithName(ConstString name) {
135*f6aab3d8Srobert if (!m_start)
136*f6aab3d8Srobert return UINT32_MAX;
137*f6aab3d8Srobert return ExtractIndexFromString(name.GetCString());
138*f6aab3d8Srobert }
139*f6aab3d8Srobert
140*f6aab3d8Srobert lldb_private::SyntheticChildrenFrontEnd *
LibcxxStdSpanSyntheticFrontEndCreator(CXXSyntheticChildren *,lldb::ValueObjectSP valobj_sp)141*f6aab3d8Srobert LibcxxStdSpanSyntheticFrontEndCreator(CXXSyntheticChildren *,
142*f6aab3d8Srobert lldb::ValueObjectSP valobj_sp) {
143*f6aab3d8Srobert if (!valobj_sp)
144*f6aab3d8Srobert return nullptr;
145*f6aab3d8Srobert CompilerType type = valobj_sp->GetCompilerType();
146*f6aab3d8Srobert if (!type.IsValid() || type.GetNumTemplateArguments() != 2)
147*f6aab3d8Srobert return nullptr;
148*f6aab3d8Srobert return new LibcxxStdSpanSyntheticFrontEnd(valobj_sp);
149*f6aab3d8Srobert }
150*f6aab3d8Srobert
151*f6aab3d8Srobert } // namespace formatters
152*f6aab3d8Srobert } // namespace lldb_private
153