llvm-project/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCClassDescriptorV2.h

//===-- AppleObjCClassDescriptorV2.h ----------------------------*- 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
//
//===----------------------------------------------------------------------===//

#ifndef liblldb_AppleObjCClassDescriptorV2_h_
#define liblldb_AppleObjCClassDescriptorV2_h_

#include <mutex>

#include "AppleObjCRuntimeV2.h"
#include "lldb/Target/ObjCLanguageRuntime.h"
#include "lldb/lldb-private.h"

namespace lldb_private {

class ClassDescriptorV2 : public ObjCLanguageRuntime::ClassDescriptor {
public:
  friend class lldb_private::AppleObjCRuntimeV2;

  ~ClassDescriptorV2() override = default;

  ConstString GetClassName() override;

  ObjCLanguageRuntime::ClassDescriptorSP GetSuperclass() override;

  ObjCLanguageRuntime::ClassDescriptorSP GetMetaclass() const override;

  bool IsValid() override {
    return true; // any Objective-C v2 runtime class descriptor we vend is valid
  }

  // a custom descriptor is used for tagged pointers
  bool GetTaggedPointerInfo(uint64_t *info_bits = nullptr,
                            uint64_t *value_bits = nullptr,
                            uint64_t *payload = nullptr) override {
    return false;
  }

  uint64_t GetInstanceSize() override;

  ObjCLanguageRuntime::ObjCISA GetISA() override { return m_objc_class_ptr; }

  bool Describe(
      std::function<void(ObjCLanguageRuntime::ObjCISA)> const &superclass_func,
      std::function<bool(const char *, const char *)> const
          &instance_method_func,
      std::function<bool(const char *, const char *)> const &class_method_func,
      std::function<bool(const char *, const char *, lldb::addr_t,
                         uint64_t)> const &ivar_func) const override;

  size_t GetNumIVars() override {
    GetIVarInformation();
    return m_ivars_storage.size();
  }

  iVarDescriptor GetIVarAtIndex(size_t idx) override {
    if (idx >= GetNumIVars())
      return iVarDescriptor();
    return m_ivars_storage[idx];
  }

protected:
  void GetIVarInformation();

private:
  static const uint32_t RW_REALIZED = (1 << 31);

  struct objc_class_t {
    ObjCLanguageRuntime::ObjCISA m_isa; // The class's metaclass.
    ObjCLanguageRuntime::ObjCISA m_superclass;
    lldb::addr_t m_cache_ptr;
    lldb::addr_t m_vtable_ptr;
    lldb::addr_t m_data_ptr;
    uint8_t m_flags;

    objc_class_t()
        : m_isa(0), m_superclass(0), m_cache_ptr(0), m_vtable_ptr(0),
          m_data_ptr(0), m_flags(0) {}

    void Clear() {
      m_isa = 0;
      m_superclass = 0;
      m_cache_ptr = 0;
      m_vtable_ptr = 0;
      m_data_ptr = 0;
      m_flags = 0;
    }

    bool Read(Process *process, lldb::addr_t addr);
  };

  struct class_ro_t {
    uint32_t m_flags;
    uint32_t m_instanceStart;
    uint32_t m_instanceSize;
    uint32_t m_reserved;

    lldb::addr_t m_ivarLayout_ptr;
    lldb::addr_t m_name_ptr;
    lldb::addr_t m_baseMethods_ptr;
    lldb::addr_t m_baseProtocols_ptr;
    lldb::addr_t m_ivars_ptr;

    lldb::addr_t m_weakIvarLayout_ptr;
    lldb::addr_t m_baseProperties_ptr;

    std::string m_name;

    bool Read(Process *process, lldb::addr_t addr);
  };

  struct class_rw_t {
    uint32_t m_flags;
    uint32_t m_version;

    lldb::addr_t m_ro_ptr;
    union {
      lldb::addr_t m_method_list_ptr;
      lldb::addr_t m_method_lists_ptr;
    };
    lldb::addr_t m_properties_ptr;
    lldb::addr_t m_protocols_ptr;

    ObjCLanguageRuntime::ObjCISA m_firstSubclass;
    ObjCLanguageRuntime::ObjCISA m_nextSiblingClass;

    bool Read(Process *process, lldb::addr_t addr);
  };

  struct method_list_t {
    uint32_t m_entsize;
    uint32_t m_count;
    lldb::addr_t m_first_ptr;

    bool Read(Process *process, lldb::addr_t addr);
  };

  struct method_t {
    lldb::addr_t m_name_ptr;
    lldb::addr_t m_types_ptr;
    lldb::addr_t m_imp_ptr;

    std::string m_name;
    std::string m_types;

    static size_t GetSize(Process *process) {
      size_t ptr_size = process->GetAddressByteSize();

      return ptr_size    // SEL name;
             + ptr_size  // const char *types;
             + ptr_size; // IMP imp;
    }

    bool Read(Process *process, lldb::addr_t addr);
  };

  struct ivar_list_t {
    uint32_t m_entsize;
    uint32_t m_count;
    lldb::addr_t m_first_ptr;

    bool Read(Process *process, lldb::addr_t addr);
  };

  struct ivar_t {
    lldb::addr_t m_offset_ptr;
    lldb::addr_t m_name_ptr;
    lldb::addr_t m_type_ptr;
    uint32_t m_alignment;
    uint32_t m_size;

    std::string m_name;
    std::string m_type;

    static size_t GetSize(Process *process) {
      size_t ptr_size = process->GetAddressByteSize();

      return ptr_size            // uintptr_t *offset;
             + ptr_size          // const char *name;
             + ptr_size          // const char *type;
             + sizeof(uint32_t)  // uint32_t alignment;
             + sizeof(uint32_t); // uint32_t size;
    }

    bool Read(Process *process, lldb::addr_t addr);
  };

  class iVarsStorage {
  public:
    iVarsStorage();

    size_t size();

    iVarDescriptor &operator[](size_t idx);

    void fill(AppleObjCRuntimeV2 &runtime, ClassDescriptorV2 &descriptor);

  private:
    bool m_filled;
    std::vector<iVarDescriptor> m_ivars;
    std::recursive_mutex m_mutex;
  };

  // The constructor should only be invoked by the runtime as it builds its
  // caches
  // or populates them.  A ClassDescriptorV2 should only ever exist in a cache.
  ClassDescriptorV2(AppleObjCRuntimeV2 &runtime,
                    ObjCLanguageRuntime::ObjCISA isa, const char *name)
      : m_runtime(runtime), m_objc_class_ptr(isa), m_name(name),
        m_ivars_storage() {}

  bool Read_objc_class(Process *process,
                       std::unique_ptr<objc_class_t> &objc_class) const;

  bool Read_class_row(Process *process, const objc_class_t &objc_class,
                      std::unique_ptr<class_ro_t> &class_ro,
                      std::unique_ptr<class_rw_t> &class_rw) const;

  AppleObjCRuntimeV2
      &m_runtime; // The runtime, so we can read information lazily.
  lldb::addr_t m_objc_class_ptr; // The address of the objc_class_t.  (I.e.,
                                 // objects of this class type have this as
                                 // their ISA)
  ConstString m_name;            // May be NULL
  iVarsStorage m_ivars_storage;
};

// tagged pointer descriptor
class ClassDescriptorV2Tagged : public ObjCLanguageRuntime::ClassDescriptor {
public:
  ClassDescriptorV2Tagged(ConstString class_name, uint64_t payload) {
    m_name = class_name;
    if (!m_name) {
      m_valid = false;
      return;
    }
    m_valid = true;
    m_payload = payload;
    m_info_bits = (m_payload & 0xF0ULL) >> 4;
    m_value_bits = (m_payload & ~0x0000000000000000FFULL) >> 8;
  }

  ClassDescriptorV2Tagged(
      ObjCLanguageRuntime::ClassDescriptorSP actual_class_sp,
      uint64_t payload) {
    if (!actual_class_sp) {
      m_valid = false;
      return;
    }
    m_name = actual_class_sp->GetClassName();
    if (!m_name) {
      m_valid = false;
      return;
    }
    m_valid = true;
    m_payload = payload;
    m_info_bits = (m_payload & 0x0FULL);
    m_value_bits = (m_payload & ~0x0FULL) >> 4;
  }

  ~ClassDescriptorV2Tagged() override = default;

  ConstString GetClassName() override { return m_name; }

  ObjCLanguageRuntime::ClassDescriptorSP GetSuperclass() override {
    // tagged pointers can represent a class that has a superclass, but since
    // that information is not
    // stored in the object itself, we would have to query the runtime to
    // discover the hierarchy
    // for the time being, we skip this step in the interest of static discovery
    return ObjCLanguageRuntime::ClassDescriptorSP();
  }

  ObjCLanguageRuntime::ClassDescriptorSP GetMetaclass() const override {
    return ObjCLanguageRuntime::ClassDescriptorSP();
  }

  bool IsValid() override { return m_valid; }

  bool IsKVO() override {
    return false; // tagged pointers are not KVO'ed
  }

  bool IsCFType() override {
    return false; // tagged pointers are not CF objects
  }

  bool GetTaggedPointerInfo(uint64_t *info_bits = nullptr,
                            uint64_t *value_bits = nullptr,
                            uint64_t *payload = nullptr) override {
    if (info_bits)
      *info_bits = GetInfoBits();
    if (value_bits)
      *value_bits = GetValueBits();
    if (payload)
      *payload = GetPayload();
    return true;
  }

  uint64_t GetInstanceSize() override {
    return (IsValid() ? m_pointer_size : 0);
  }

  ObjCLanguageRuntime::ObjCISA GetISA() override {
    return 0; // tagged pointers have no ISA
  }

  // these calls are not part of any formal tagged pointers specification
  virtual uint64_t GetValueBits() { return (IsValid() ? m_value_bits : 0); }

  virtual uint64_t GetInfoBits() { return (IsValid() ? m_info_bits : 0); }

  virtual uint64_t GetPayload() { return (IsValid() ? m_payload : 0); }

private:
  ConstString m_name;
  uint8_t m_pointer_size;
  bool m_valid;
  uint64_t m_info_bits;
  uint64_t m_value_bits;
  uint64_t m_payload;
};

} // namespace lldb_private

#endif // liblldb_AppleObjCClassDescriptorV2_h_