text: //===-- ValueObjectChild.cpp ------------------------------------*- C++ -*-===//
  //
  // 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 "lldb/Core/ValueObjectChild.h"
  
  #include "lldb/Core/Value.h"
  #include "lldb/Symbol/CompilerType.h"
  #include "lldb/Target/ExecutionContext.h"
  #include "lldb/Target/LanguageRuntime.h"
  #include "lldb/Target/Process.h"
  #include "lldb/Utility/Flags.h"
  #include "lldb/Utility/Scalar.h"
  #include "lldb/Utility/Status.h"
  #include "lldb/lldb-forward.h"
  
  #include <functional>
  #include <memory>
  #include <vector>
  
  #include <stdio.h>
  #include <string.h>
  
  using namespace lldb_private;
  
  ValueObjectChild::ValueObjectChild(
      ValueObject &parent, const CompilerType &compiler_type,
      ConstString name, uint64_t byte_size, int32_t byte_offset,
      uint32_t bitfield_bit_size, uint32_t bitfield_bit_offset,
      bool is_base_class, bool is_deref_of_parent,
      AddressType child_ptr_or_ref_addr_type, uint64_t language_flags)
      : ValueObject(parent), m_compiler_type(compiler_type),
        m_byte_size(byte_size), m_byte_offset(byte_offset),
        m_bitfield_bit_size(bitfield_bit_size),
        m_bitfield_bit_offset(bitfield_bit_offset),
        m_is_base_class(is_base_class), m_is_deref_of_parent(is_deref_of_parent),
        m_can_update_with_invalid_exe_ctx() {
    m_name = name;
    SetAddressTypeOfChildren(child_ptr_or_ref_addr_type);
    SetLanguageFlags(language_flags);
  }
  
  ValueObjectChild::~ValueObjectChild() {}
  
  lldb::ValueType ValueObjectChild::GetValueType() const {
    return m_parent->GetValueType();
  }
  
  size_t ValueObjectChild::CalculateNumChildren(uint32_t max) {
    ExecutionContext exe_ctx(GetExecutionContextRef());
    auto children_count = GetCompilerType().GetNumChildren(true, &exe_ctx);
    return children_count <= max ? children_count : max;
  }
  
  static void AdjustForBitfieldness(ConstString &name,
                                    uint8_t bitfield_bit_size) {
    if (name && bitfield_bit_size) {
      const char *compiler_type_name = name.AsCString();
      if (compiler_type_name) {
        std::vector<char> bitfield_type_name(strlen(compiler_type_name) + 32, 0);
        ::snprintf(&bitfield_type_name.front(), bitfield_type_name.size(),
                   "%s:%u", compiler_type_name, bitfield_bit_size);
        name.SetCString(&bitfield_type_name.front());
      }
    }
  }
  
  ConstString ValueObjectChild::GetTypeName() {
    if (m_type_name.IsEmpty()) {
      m_type_name = GetCompilerType().GetConstTypeName();
      AdjustForBitfieldness(m_type_name, m_bitfield_bit_size);
    }
    return m_type_name;
  }
  
  ConstString ValueObjectChild::GetQualifiedTypeName() {
    ConstString qualified_name = GetCompilerType().GetConstTypeName();
    AdjustForBitfieldness(qualified_name, m_bitfield_bit_size);
    return qualified_name;
  }
  
  ConstString ValueObjectChild::GetDisplayTypeName() {
    const SymbolContext *sc = nullptr;
    if (GetFrameSP())
      sc = &GetFrameSP()->GetSymbolContext(lldb::eSymbolContextFunction);
    ConstString display_name = GetCompilerType().GetDisplayTypeName(sc);
    AdjustForBitfieldness(display_name, m_bitfield_bit_size);
    return display_name;
  }
  
  LazyBool ValueObjectChild::CanUpdateWithInvalidExecutionContext() {
    if (m_can_update_with_invalid_exe_ctx.hasValue())
      return m_can_update_with_invalid_exe_ctx.getValue();
    if (m_parent) {
      ValueObject *opinionated_parent =
          m_parent->FollowParentChain([](ValueObject *valobj) -> bool {
            return (valobj->CanUpdateWithInvalidExecutionContext() ==
                    eLazyBoolCalculate);
          });
      if (opinionated_parent)
        return (m_can_update_with_invalid_exe_ctx =
                    opinionated_parent->CanUpdateWithInvalidExecutionContext())
            .getValue();
    }
    return (m_can_update_with_invalid_exe_ctx =
                this->ValueObject::CanUpdateWithInvalidExecutionContext())
        .getValue();
  }
  
  bool ValueObjectChild::UpdateValue() {
    m_error.Clear();
    SetValueIsValid(false);
    ValueObject *parent = m_parent;
    if (parent) {
      if (parent->UpdateValueIfNeeded(false)) {
        m_value.SetCompilerType(GetCompilerType());
  
        CompilerType parent_type(parent->GetCompilerType());
        // Copy the parent scalar value and the scalar value type
        m_value.GetScalar() = parent->GetValue().GetScalar();
        Value::ValueType value_type = parent->GetValue().GetValueType();
        m_value.SetValueType(value_type);
  
        Flags parent_type_flags(parent_type.GetTypeInfo());
        const bool is_instance_ptr_base =
            ((m_is_base_class) &&
             (parent_type_flags.AnySet(lldb::eTypeInstanceIsPointer)));
  
        if (parent->GetCompilerType().ShouldTreatScalarValueAsAddress()) {
          lldb::addr_t addr = parent->GetPointerValue();
  
          // BEGIN Swift
          if (parent_type_flags.AnySet(lldb::eTypeInstanceIsPointer))
            if (auto process_sp = GetProcessSP())
              if (auto runtime = process_sp->GetLanguageRuntime(
                      parent_type.GetMinimumLanguage())) {
                bool deref;
                std::tie(addr, deref) =
                    runtime->FixupPointerValue(addr, parent_type);
                if (deref) {
                  // Read the pointer to the Objective-C object.
                  Target &target = process_sp->GetTarget();
                  size_t ptr_size = process_sp->GetAddressByteSize();
                  target.ReadMemory(addr, false, &addr, ptr_size, m_error);
                }
              }
          // END Swift
  
          m_value.GetScalar() = addr;
  
          if (addr == LLDB_INVALID_ADDRESS) {
            m_error.SetErrorString("parent address is invalid.");
          } else if (addr == 0) {
            m_error.SetErrorString("parent is NULL");
          } else {
            m_value.GetScalar() += m_byte_offset;
            AddressType addr_type = parent->GetAddressTypeOfChildren();
  
            switch (addr_type) {
            case eAddressTypeFile: {
              lldb::ProcessSP process_sp(GetProcessSP());
              if (process_sp && process_sp->IsAlive())
                m_value.SetValueType(Value::eValueTypeLoadAddress);
              else
                m_value.SetValueType(Value::eValueTypeFileAddress);
            } break;
            case eAddressTypeLoad:
              // BEGIN SWIFT MOD
              // We need to detect when we cross TypeSystem boundaries,
              // e.g. when we try to print Obj-C fields of a Swift object.
              if (parent->GetCompilerType().GetTypeSystem()->getKind() ==
                  GetCompilerType().GetTypeSystem()->getKind())
                  m_value.SetValueType(is_instance_ptr_base
                                      ? Value::eValueTypeScalar
                                      : Value::eValueTypeLoadAddress);
              else
                m_value.SetValueType(Value::eValueTypeLoadAddress);
              // END SWIFT MOD
              break;
            case eAddressTypeHost:
              m_value.SetValueType(Value::eValueTypeHostAddress);
              break;
            case eAddressTypeInvalid:
              // TODO: does this make sense?
              m_value.SetValueType(Value::eValueTypeScalar);
              break;
            }
          }
        } else {
          switch (value_type) {
          case Value::eValueTypeLoadAddress:
          case Value::eValueTypeFileAddress:
          case Value::eValueTypeHostAddress: {
            lldb::addr_t addr =
                m_value.GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
            if (addr == LLDB_INVALID_ADDRESS) {
              m_error.SetErrorString("parent address is invalid.");
            } else if (addr == 0) {
              m_error.SetErrorString("parent is NULL");
            } else {
              // Set this object's scalar value to the address of its value by
              // adding its byte offset to the parent address
              m_value.GetScalar() += GetByteOffset();
  
              // If a bitfield doesn't fit into the child_byte_size'd
              // window at child_byte_offset, move the window forward
              // until it fits.  The problem here is that Value has no
              // notion of bitfields and thus the Value's DataExtractor
              // is sized like the bitfields CompilerType; a sequence of
              // bitfields, however, can be larger than their underlying
              // type.
              if (m_bitfield_bit_offset) {
                const bool thread_and_frame_only_if_stopped = true;
                ExecutionContext exe_ctx(GetExecutionContextRef().Lock(
                    thread_and_frame_only_if_stopped));
                if (auto type_bit_size = GetCompilerType().GetBitSize(
                        exe_ctx.GetBestExecutionContextScope())) {
                  uint64_t bitfield_end =
                      m_bitfield_bit_size + m_bitfield_bit_offset;
                  if (bitfield_end > *type_bit_size) {
                    uint64_t overhang_bytes =
                        (bitfield_end - *type_bit_size + 7) / 8;
                    m_value.GetScalar() += overhang_bytes;
                    m_bitfield_bit_offset -= overhang_bytes * 8;
                  }
                }
              }
            }
          } break;
  
          case Value::eValueTypeScalar:
            // try to extract the child value from the parent's scalar value
            {
              Scalar scalar(m_value.GetScalar());
              if (m_bitfield_bit_size)
                scalar.ExtractBitfield(m_bitfield_bit_size,
                                       m_bitfield_bit_offset);
              else
                scalar.ExtractBitfield(8 * m_byte_size, 8 * m_byte_offset);
              m_value.GetScalar() = scalar;
            }
            break;
          default:
            m_error.SetErrorString("parent has invalid value.");
            break;
          }
        }
  
        if (m_error.Success()) {
          const bool thread_and_frame_only_if_stopped = true;
          ExecutionContext exe_ctx(
              GetExecutionContextRef().Lock(thread_and_frame_only_if_stopped));
          if (GetCompilerType().GetTypeInfo() & lldb::eTypeHasValue) {
            Value &value = is_instance_ptr_base ? m_parent->GetValue() : m_value;
            m_error =
                value.GetValueAsData(&exe_ctx, m_data, GetModule().get());
          } else {
            m_error.Clear(); // No value so nothing to read...
          }
        }
  
      } else {
        m_error.SetErrorStringWithFormat("parent failed to evaluate: %s",
                                         parent->GetError().AsCString());
      }
    } else {
      m_error.SetErrorString("ValueObjectChild has a NULL parent ValueObject.");
    }
  
    return m_error.Success();
  }
  
  bool ValueObjectChild::IsInScope() {
    ValueObject *root(GetRoot());
    if (root)
      return root->IsInScope();
    return false;
  }
  