1 files changed, 194 insertions, 0 deletions
diff --git a/contrib/llvm-project/lldb/source/Plugins/Language/CPlusPlus/LibCxxProxyArray.cpp b/contrib/llvm-project/lldb/source/Plugins/Language/CPlusPlus/LibCxxProxyArray.cpp
new file mode 100644
index 000000000000..726f06523b97
--- /dev/null
+++ b/contrib/llvm-project/lldb/source/Plugins/Language/CPlusPlus/LibCxxProxyArray.cpp
@@ -0,0 +1,194 @@
+//===-- LibCxxProxyArray.cpp-----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "LibCxx.h"
+
+#include "lldb/Core/ValueObject.h"
+#include "lldb/DataFormatters/FormattersHelpers.h"
+#include <optional>
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::formatters;
+
+namespace lldb_private {
+namespace formatters {
+
+/// Data formatter for libc++'s std::"proxy_array".
+///
+/// A proxy_array's are created by using:
+///   std::gslice_array   operator[](const std::gslice& gslicearr);
+///   std::mask_array     operator[](const std::valarray<bool>& boolarr);
+///   std::indirect_array operator[](const std::valarray<std::size_t>& indarr);
+///
+/// These arrays have the following members:
+/// - __vp_ points to std::valarray::__begin_
+/// - __1d_ an array of offsets of the elements from @a __vp_
+class LibcxxStdProxyArraySyntheticFrontEnd : public SyntheticChildrenFrontEnd {
+public:
+  LibcxxStdProxyArraySyntheticFrontEnd(lldb::ValueObjectSP valobj_sp);
+
+  ~LibcxxStdProxyArraySyntheticFrontEnd() override;
+
+  llvm::Expected<uint32_t> CalculateNumChildren() override;
+
+  lldb::ValueObjectSP GetChildAtIndex(uint32_t idx) override;
+
+  lldb::ChildCacheState Update() override;
+
+  bool MightHaveChildren() override;
+
+  size_t GetIndexOfChildWithName(ConstString name) override;
+
+private:
+  /// A non-owning pointer to the array's __vp_.
+  ValueObject *m_base = nullptr;
+  /// The type of the array's template argument T.
+  CompilerType m_element_type;
+  /// The sizeof the array's template argument T.
+  uint32_t m_element_size = 0;
+
+  /// A non-owning pointer to the array's __1d_.__begin_.
+  ValueObject *m_start = nullptr;
+  /// A non-owning pointer to the array's __1d_.__end_.
+  ValueObject *m_finish = nullptr;
+  /// The type of the __1d_ array's template argument T (size_t).
+  CompilerType m_element_type_size_t;
+  /// The sizeof the __1d_ array's template argument T (size_t)
+  uint32_t m_element_size_size_t = 0;
+};
+
+} // namespace formatters
+} // namespace lldb_private
+
+lldb_private::formatters::LibcxxStdProxyArraySyntheticFrontEnd::
+    LibcxxStdProxyArraySyntheticFrontEnd(lldb::ValueObjectSP valobj_sp)
+    : SyntheticChildrenFrontEnd(*valobj_sp), m_element_type() {
+  if (valobj_sp)
+    Update();
+}
+
+lldb_private::formatters::LibcxxStdProxyArraySyntheticFrontEnd::
+    ~LibcxxStdProxyArraySyntheticFrontEnd() {
+  // these need to stay around because they are child objects who will follow
+  // their parent's life cycle
+  // delete m_base;
+}
+
+llvm::Expected<uint32_t> lldb_private::formatters::
+    LibcxxStdProxyArraySyntheticFrontEnd::CalculateNumChildren() {
+
+  if (!m_start || !m_finish)
+    return 0;
+  uint64_t start_val = m_start->GetValueAsUnsigned(0);
+  uint64_t finish_val = m_finish->GetValueAsUnsigned(0);
+
+  if (start_val == 0 || finish_val == 0)
+    return 0;
+
+  if (start_val >= finish_val)
+    return 0;
+
+  size_t num_children = (finish_val - start_val);
+  if (num_children % m_element_size_size_t)
+    return 0;
+  return num_children / m_element_size_size_t;
+}
+
+lldb::ValueObjectSP
+lldb_private::formatters::LibcxxStdProxyArraySyntheticFrontEnd::GetChildAtIndex(
+    uint32_t idx) {
+  if (!m_base)
+    return lldb::ValueObjectSP();
+
+  uint64_t offset = idx * m_element_size_size_t;
+  offset = offset + m_start->GetValueAsUnsigned(0);
+
+  lldb::ValueObjectSP indirect = CreateValueObjectFromAddress(
+      "", offset, m_backend.GetExecutionContextRef(), m_element_type_size_t);
+  if (!indirect)
+    return lldb::ValueObjectSP();
+
+  const size_t value = indirect->GetValueAsUnsigned(0);
+  if (!value)
+    return lldb::ValueObjectSP();
+
+  offset = value * m_element_size;
+  offset = offset + m_base->GetValueAsUnsigned(0);
+
+  StreamString name;
+  name.Printf("[%" PRIu64 "] -> [%zu]", (uint64_t)idx, value);
+  return CreateValueObjectFromAddress(name.GetString(), offset,
+                                      m_backend.GetExecutionContextRef(),
+                                      m_element_type);
+}
+
+lldb::ChildCacheState
+lldb_private::formatters::LibcxxStdProxyArraySyntheticFrontEnd::Update() {
+  m_base = nullptr;
+  m_start = nullptr;
+  m_finish = nullptr;
+
+  CompilerType type = m_backend.GetCompilerType();
+  if (type.GetNumTemplateArguments() == 0)
+    return ChildCacheState::eRefetch;
+
+  m_element_type = type.GetTypeTemplateArgument(0);
+  if (std::optional<uint64_t> size = m_element_type.GetByteSize(nullptr))
+    m_element_size = *size;
+
+  if (m_element_size == 0)
+    return ChildCacheState::eRefetch;
+
+  ValueObjectSP vector = m_backend.GetChildMemberWithName("__1d_");
+  if (!vector)
+    return ChildCacheState::eRefetch;
+
+  type = vector->GetCompilerType();
+  if (type.GetNumTemplateArguments() == 0)
+    return ChildCacheState::eRefetch;
+
+  m_element_type_size_t = type.GetTypeTemplateArgument(0);
+  if (std::optional<uint64_t> size = m_element_type_size_t.GetByteSize(nullptr))
+    m_element_size_size_t = *size;
+
+  if (m_element_size_size_t == 0)
+    return ChildCacheState::eRefetch;
+
+  ValueObjectSP base = m_backend.GetChildMemberWithName("__vp_");
+  ValueObjectSP start = vector->GetChildMemberWithName("__begin_");
+  ValueObjectSP finish = vector->GetChildMemberWithName("__end_");
+  if (!base || !start || !finish)
+    return ChildCacheState::eRefetch;
+
+  m_base = base.get();
+  m_start = start.get();
+  m_finish = finish.get();
+
+  return ChildCacheState::eRefetch;
+}
+
+bool lldb_private::formatters::LibcxxStdProxyArraySyntheticFrontEnd::
+    MightHaveChildren() {
+  return true;
+}
+
+size_t lldb_private::formatters::LibcxxStdProxyArraySyntheticFrontEnd::
+    GetIndexOfChildWithName(ConstString name) {
+  if (!m_base)
+    return std::numeric_limits<size_t>::max();
+  return ExtractIndexFromString(name.GetCString());
+}
+
+lldb_private::SyntheticChildrenFrontEnd *
+lldb_private::formatters::LibcxxStdProxyArraySyntheticFrontEndCreator(
+    CXXSyntheticChildren *, lldb::ValueObjectSP valobj_sp) {
+  if (!valobj_sp)
+    return nullptr;
+  return new LibcxxStdProxyArraySyntheticFrontEnd(valobj_sp);
+}