ABIMacOSX_arm64.cpp

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//===-- ABIMacOSX_arm64.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 "ABIMacOSX_arm64.h"
 
#include <vector>
 
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Triple.h"
 
#include "lldb/Core/Module.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/Value.h"
#include "lldb/Core/ValueObjectConstResult.h"
#include "lldb/Symbol/UnwindPlan.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Utility/ConstString.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/RegisterValue.h"
#include "lldb/Utility/Scalar.h"
#include "lldb/Utility/Status.h"
 
#include "Utility/ARM64_DWARF_Registers.h"
 
using namespace lldb;
using namespace lldb_private;
 
static const char *pluginDesc = "Mac OS X ABI for arm64 targets";
 
size_t ABIMacOSX_arm64::GetRedZoneSize() const { return 128; }
 
// Static Functions
 
ABISP
ABIMacOSX_arm64::CreateInstance(ProcessSP process_sp, const ArchSpec &arch) {
  const llvm::Triple::ArchType arch_type = arch.GetTriple().getArch();
  const llvm::Triple::VendorType vendor_type = arch.GetTriple().getVendor();
 
  if (vendor_type == llvm::Triple::Apple) {
    if (arch_type == llvm::Triple::aarch64 ||
        arch_type == llvm::Triple::aarch64_32) {
      return ABISP(
          new ABIMacOSX_arm64(std::move(process_sp), MakeMCRegisterInfo(arch)));
    }
  }
 
  return ABISP();
}
 
bool ABIMacOSX_arm64::PrepareTrivialCall(
    Thread &thread, lldb::addr_t sp, lldb::addr_t func_addr,
    lldb::addr_t return_addr, llvm::ArrayRef<lldb::addr_t> args) const {
  RegisterContext *reg_ctx = thread.GetRegisterContext().get();
  if (!reg_ctx)
    return false;
 
  Log *log = GetLog(LLDBLog::Expressions);
 
  if (log) {
    StreamString s;
    s.Printf("ABIMacOSX_arm64::PrepareTrivialCall (tid = 0x%" PRIx64
             ", sp = 0x%" PRIx64 ", func_addr = 0x%" PRIx64
             ", return_addr = 0x%" PRIx64,
             thread.GetID(), (uint64_t)sp, (uint64_t)func_addr,
             (uint64_t)return_addr);
 
    for (size_t i = 0; i < args.size(); ++i)
      s.Printf(", arg%d = 0x%" PRIx64, static_cast<int>(i + 1), args[i]);
    s.PutCString(")");
    log->PutString(s.GetString());
  }
 
  const uint32_t pc_reg_num = reg_ctx->ConvertRegisterKindToRegisterNumber(
      eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
  const uint32_t sp_reg_num = reg_ctx->ConvertRegisterKindToRegisterNumber(
      eRegisterKindGeneric, LLDB_REGNUM_GENERIC_SP);
  const uint32_t ra_reg_num = reg_ctx->ConvertRegisterKindToRegisterNumber(
      eRegisterKindGeneric, LLDB_REGNUM_GENERIC_RA);
 
  // x0 - x7 contain first 8 simple args
  if (args.size() > 8) // TODO handle more than 8 arguments
    return false;
 
  for (size_t i = 0; i < args.size(); ++i) {
    const RegisterInfo *reg_info = reg_ctx->GetRegisterInfo(
        eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG1 + i);
    LLDB_LOGF(log, "About to write arg%d (0x%" PRIx64 ") into %s",
              static_cast<int>(i + 1), args[i], reg_info->name);
    if (!reg_ctx->WriteRegisterFromUnsigned(reg_info, args[i]))
      return false;
  }
 
  // Set "lr" to the return address
  if (!reg_ctx->WriteRegisterFromUnsigned(
          reg_ctx->GetRegisterInfoAtIndex(ra_reg_num), return_addr))
    return false;
 
  // Set "sp" to the requested value
  if (!reg_ctx->WriteRegisterFromUnsigned(
          reg_ctx->GetRegisterInfoAtIndex(sp_reg_num), sp))
    return false;
 
  // Set "pc" to the address requested
  if (!reg_ctx->WriteRegisterFromUnsigned(
          reg_ctx->GetRegisterInfoAtIndex(pc_reg_num), func_addr))
    return false;
 
  return true;
}
 
bool ABIMacOSX_arm64::GetArgumentValues(Thread &thread,
                                        ValueList &values) const {
  uint32_t num_values = values.GetSize();
 
  ExecutionContext exe_ctx(thread.shared_from_this());
 
  // Extract the register context so we can read arguments from registers
 
  RegisterContext *reg_ctx = thread.GetRegisterContext().get();
 
  if (!reg_ctx)
    return false;
 
  addr_t sp = 0;
 
  for (uint32_t value_idx = 0; value_idx < num_values; ++value_idx) {
    // We currently only support extracting values with Clang QualTypes. Do we
    // care about others?
    Value *value = values.GetValueAtIndex(value_idx);
 
    if (!value)
      return false;
 
    CompilerType value_type = value->GetCompilerType();
    llvm::Optional<uint64_t> bit_size = value_type.GetBitSize(&thread);
    if (!bit_size)
      return false;
 
    bool is_signed = false;
    size_t bit_width = 0;
    if (value_type.IsIntegerOrEnumerationType(is_signed)) {
      bit_width = *bit_size;
    } else if (value_type.IsPointerOrReferenceType()) {
      bit_width = *bit_size;
    } else {
      // We only handle integer, pointer and reference types currently...
      return false;
    }
 
    if (bit_width <= (exe_ctx.GetProcessRef().GetAddressByteSize() * 8)) {
      if (value_idx < 8) {
        // Arguments 1-6 are in x0-x5...
        const RegisterInfo *reg_info = nullptr;
        // Search by generic ID first, then fall back to by name
        uint32_t arg_reg_num = reg_ctx->ConvertRegisterKindToRegisterNumber(
            eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG1 + value_idx);
        if (arg_reg_num != LLDB_INVALID_REGNUM) {
          reg_info = reg_ctx->GetRegisterInfoAtIndex(arg_reg_num);
        } else {
          switch (value_idx) {
          case 0:
            reg_info = reg_ctx->GetRegisterInfoByName("x0");
            break;
          case 1:
            reg_info = reg_ctx->GetRegisterInfoByName("x1");
            break;
          case 2:
            reg_info = reg_ctx->GetRegisterInfoByName("x2");
            break;
          case 3:
            reg_info = reg_ctx->GetRegisterInfoByName("x3");
            break;
          case 4:
            reg_info = reg_ctx->GetRegisterInfoByName("x4");
            break;
          case 5:
            reg_info = reg_ctx->GetRegisterInfoByName("x5");
            break;
          case 6:
            reg_info = reg_ctx->GetRegisterInfoByName("x6");
            break;
          case 7:
            reg_info = reg_ctx->GetRegisterInfoByName("x7");
            break;
          }
        }
 
        if (reg_info) {
          RegisterValue reg_value;
 
          if (reg_ctx->ReadRegister(reg_info, reg_value)) {
            if (is_signed)
              reg_value.SignExtend(bit_width);
            if (!reg_value.GetScalarValue(value->GetScalar()))
              return false;
            continue;
          }
        }
        return false;
      } else {
        if (sp == 0) {
          // Read the stack pointer if we already haven't read it
          sp = reg_ctx->GetSP(0);
          if (sp == 0)
            return false;
        }
 
        // Arguments 5 on up are on the stack
        const uint32_t arg_byte_size = (bit_width + (8 - 1)) / 8;
        Status error;
        if (!exe_ctx.GetProcessRef().ReadScalarIntegerFromMemory(
                sp, arg_byte_size, is_signed, value->GetScalar(), error))
          return false;
 
        sp += arg_byte_size;
        // Align up to the next 8 byte boundary if needed
        if (sp % 8) {
          sp >>= 3;
          sp += 1;
          sp <<= 3;
        }
      }
    }
  }
  return true;
}
 
Status
ABIMacOSX_arm64::SetReturnValueObject(lldb::StackFrameSP &frame_sp,
                                      lldb::ValueObjectSP &new_value_sp) {
  Status error;
  if (!new_value_sp) {
    error.SetErrorString("Empty value object for return value.");
    return error;
  }
 
  CompilerType return_value_type = new_value_sp->GetCompilerType();
  if (!return_value_type) {
    error.SetErrorString("Null clang type for return value.");
    return error;
  }
 
  Thread *thread = frame_sp->GetThread().get();
 
  RegisterContext *reg_ctx = thread->GetRegisterContext().get();
 
  if (reg_ctx) {
    DataExtractor data;
    Status data_error;
    const uint64_t byte_size = new_value_sp->GetData(data, data_error);
    if (data_error.Fail()) {
      error.SetErrorStringWithFormat(
          "Couldn't convert return value to raw data: %s",
          data_error.AsCString());
      return error;
    }
 
    const uint32_t type_flags = return_value_type.GetTypeInfo(nullptr);
    if (type_flags & eTypeIsScalar || type_flags & eTypeIsPointer) {
      if (type_flags & eTypeIsInteger || type_flags & eTypeIsPointer) {
        // Extract the register context so we can read arguments from registers
        lldb::offset_t offset = 0;
        if (byte_size <= 16) {
          const RegisterInfo *x0_info = reg_ctx->GetRegisterInfoByName("x0", 0);
          if (byte_size <= 8) {
            uint64_t raw_value = data.GetMaxU64(&offset, byte_size);
 
            if (!reg_ctx->WriteRegisterFromUnsigned(x0_info, raw_value))
              error.SetErrorString("failed to write register x0");
          } else {
            uint64_t raw_value = data.GetMaxU64(&offset, 8);
 
            if (reg_ctx->WriteRegisterFromUnsigned(x0_info, raw_value)) {
              const RegisterInfo *x1_info =
                  reg_ctx->GetRegisterInfoByName("x1", 0);
              raw_value = data.GetMaxU64(&offset, byte_size - offset);
 
              if (!reg_ctx->WriteRegisterFromUnsigned(x1_info, raw_value))
                error.SetErrorString("failed to write register x1");
            }
          }
        } else {
          error.SetErrorString("We don't support returning longer than 128 bit "
                               "integer values at present.");
        }
      } else if (type_flags & eTypeIsFloat) {
        if (type_flags & eTypeIsComplex) {
          // Don't handle complex yet.
          error.SetErrorString(
              "returning complex float values are not supported");
        } else {
          const RegisterInfo *v0_info = reg_ctx->GetRegisterInfoByName("v0", 0);
 
          if (v0_info) {
            if (byte_size <= 16) {
              if (byte_size <= RegisterValue::GetMaxByteSize()) {
                RegisterValue reg_value;
                error = reg_value.SetValueFromData(v0_info, data, 0, true);
                if (error.Success()) {
                  if (!reg_ctx->WriteRegister(v0_info, reg_value))
                    error.SetErrorString("failed to write register v0");
                }
              } else {
                error.SetErrorStringWithFormat(
                    "returning float values with a byte size of %" PRIu64
                    " are not supported",
                    byte_size);
              }
            } else {
              error.SetErrorString("returning float values longer than 128 "
                                   "bits are not supported");
            }
          } else {
            error.SetErrorString("v0 register is not available on this target");
          }
        }
      }
    } else if (type_flags & eTypeIsVector) {
      if (byte_size > 0) {
        const RegisterInfo *v0_info = reg_ctx->GetRegisterInfoByName("v0", 0);
 
        if (v0_info) {
          if (byte_size <= v0_info->byte_size) {
            RegisterValue reg_value;
            error = reg_value.SetValueFromData(v0_info, data, 0, true);
            if (error.Success()) {
              if (!reg_ctx->WriteRegister(v0_info, reg_value))
                error.SetErrorString("failed to write register v0");
            }
          }
        }
      }
    }
  } else {
    error.SetErrorString("no registers are available");
  }
 
  return error;
}
 
bool ABIMacOSX_arm64::CreateFunctionEntryUnwindPlan(UnwindPlan &unwind_plan) {
  unwind_plan.Clear();
  unwind_plan.SetRegisterKind(eRegisterKindDWARF);
 
  uint32_t lr_reg_num = arm64_dwarf::lr;
  uint32_t sp_reg_num = arm64_dwarf::sp;
  uint32_t pc_reg_num = arm64_dwarf::pc;
 
  UnwindPlan::RowSP row(new UnwindPlan::Row);
 
  // Our previous Call Frame Address is the stack pointer
  row->GetCFAValue().SetIsRegisterPlusOffset(sp_reg_num, 0);
 
  // Our previous PC is in the LR
  row->SetRegisterLocationToRegister(pc_reg_num, lr_reg_num, true);
 
  unwind_plan.AppendRow(row);
 
  // All other registers are the same.
 
  unwind_plan.SetSourceName("arm64 at-func-entry default");
  unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
 
  return true;
}
 
bool ABIMacOSX_arm64::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
  unwind_plan.Clear();
  unwind_plan.SetRegisterKind(eRegisterKindDWARF);
 
  uint32_t fp_reg_num = arm64_dwarf::fp;
  uint32_t pc_reg_num = arm64_dwarf::pc;
 
  UnwindPlan::RowSP row(new UnwindPlan::Row);
  const int32_t ptr_size = 8;
 
  row->GetCFAValue().SetIsRegisterPlusOffset(fp_reg_num, 2 * ptr_size);
  row->SetOffset(0);
  row->SetUnspecifiedRegistersAreUndefined(true);
 
  row->SetRegisterLocationToAtCFAPlusOffset(fp_reg_num, ptr_size * -2, true);
  row->SetRegisterLocationToAtCFAPlusOffset(pc_reg_num, ptr_size * -1, true);
 
  unwind_plan.AppendRow(row);
  unwind_plan.SetSourceName("arm64-apple-darwin default unwind plan");
  unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
  unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
  return true;
}
 
// AAPCS64 (Procedure Call Standard for the ARM 64-bit Architecture) says
// registers x19 through x28 and sp are callee preserved. v8-v15 are non-
// volatile (and specifically only the lower 8 bytes of these regs), the rest
// of the fp/SIMD registers are volatile.
//
// v. https://github.com/ARM-software/abi-aa/blob/main/aapcs64/
 
// We treat x29 as callee preserved also, else the unwinder won't try to
// retrieve fp saves.
 
bool ABIMacOSX_arm64::RegisterIsVolatile(const RegisterInfo *reg_info) {
  if (reg_info) {
    const char *name = reg_info->name;
 
    // Sometimes we'll be called with the "alternate" name for these registers;
    // recognize them as non-volatile.
 
    if (name[0] == 'p' && name[1] == 'c') // pc
      return false;
    if (name[0] == 'f' && name[1] == 'p') // fp
      return false;
    if (name[0] == 's' && name[1] == 'p') // sp
      return false;
    if (name[0] == 'l' && name[1] == 'r') // lr
      return false;
 
    if (name[0] == 'x') {
      // Volatile registers: x0-x18, x30 (lr)
      // Return false for the non-volatile gpr regs, true for everything else
      switch (name[1]) {
      case '1':
        switch (name[2]) {
        case '9':
          return false; // x19 is non-volatile
        default:
          return true;
        }
        break;
      case '2':
        switch (name[2]) {
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
          return false; // x20 - 28 are non-volatile
        case '9':
          return false; // x29 aka fp treat as non-volatile on Darwin
        default:
          return true;
        }
      case '3': // x30 aka lr treat as non-volatile
        if (name[2] == '0')
          return false;
        break;
      default:
        return true;
      }
    } else if (name[0] == 'v' || name[0] == 's' || name[0] == 'd') {
      // Volatile registers: v0-7, v16-v31
      // Return false for non-volatile fp/SIMD regs, true for everything else
      switch (name[1]) {
      case '8':
      case '9':
        return false; // v8-v9 are non-volatile
      case '1':
        switch (name[2]) {
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
          return false; // v10-v15 are non-volatile
        default:
          return true;
        }
      default:
        return true;
      }
    }
  }
  return true;
}
 
static bool LoadValueFromConsecutiveGPRRegisters(
    ExecutionContext &exe_ctx, RegisterContext *reg_ctx,
    const CompilerType &value_type,
    bool is_return_value, // false => parameter, true => return value
    uint32_t &NGRN,       // NGRN (see ABI documentation)
    uint32_t &NSRN,       // NSRN (see ABI documentation)
    DataExtractor &data) {
  llvm::Optional<uint64_t> byte_size =
      value_type.GetByteSize(exe_ctx.GetBestExecutionContextScope());
  if (!byte_size || *byte_size == 0)
    return false;
 
  std::unique_ptr<DataBufferHeap> heap_data_up(
      new DataBufferHeap(*byte_size, 0));
  const ByteOrder byte_order = exe_ctx.GetProcessRef().GetByteOrder();
  Status error;
 
  CompilerType base_type;
  const uint32_t homogeneous_count =
      value_type.IsHomogeneousAggregate(&base_type);
  if (homogeneous_count > 0 && homogeneous_count <= 8) {
    // Make sure we have enough registers
    if (NSRN < 8 && (8 - NSRN) >= homogeneous_count) {
      if (!base_type)
        return false;
      llvm::Optional<uint64_t> base_byte_size =
          base_type.GetByteSize(exe_ctx.GetBestExecutionContextScope());
      if (!base_byte_size)
        return false;
      uint32_t data_offset = 0;
 
      for (uint32_t i = 0; i < homogeneous_count; ++i) {
        char v_name[8];
        ::snprintf(v_name, sizeof(v_name), "v%u", NSRN);
        const RegisterInfo *reg_info =
            reg_ctx->GetRegisterInfoByName(v_name, 0);
        if (reg_info == nullptr)
          return false;
 
        if (*base_byte_size > reg_info->byte_size)
          return false;
 
        RegisterValue reg_value;
 
        if (!reg_ctx->ReadRegister(reg_info, reg_value))
          return false;
 
        // Make sure we have enough room in "heap_data_up"
        if ((data_offset + *base_byte_size) <= heap_data_up->GetByteSize()) {
          const size_t bytes_copied = reg_value.GetAsMemoryData(
              reg_info, heap_data_up->GetBytes() + data_offset, *base_byte_size,
              byte_order, error);
          if (bytes_copied != *base_byte_size)
            return false;
          data_offset += bytes_copied;
          ++NSRN;
        } else
          return false;
      }
      data.SetByteOrder(byte_order);
      data.SetAddressByteSize(exe_ctx.GetProcessRef().GetAddressByteSize());
      data.SetData(DataBufferSP(heap_data_up.release()));
      return true;
    }
  }
 
  const size_t max_reg_byte_size = 16;
  if (*byte_size <= max_reg_byte_size) {
    size_t bytes_left = *byte_size;
    uint32_t data_offset = 0;
    while (data_offset < *byte_size) {
      if (NGRN >= 8)
        return false;
 
      uint32_t reg_num = reg_ctx->ConvertRegisterKindToRegisterNumber(
          eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG1 + NGRN);
      if (reg_num == LLDB_INVALID_REGNUM)
        return false;
 
      const RegisterInfo *reg_info = reg_ctx->GetRegisterInfoAtIndex(reg_num);
      if (reg_info == nullptr)
        return false;
 
      RegisterValue reg_value;
 
      if (!reg_ctx->ReadRegister(reg_info, reg_value))
        return false;
 
      const size_t curr_byte_size = std::min<size_t>(8, bytes_left);
      const size_t bytes_copied = reg_value.GetAsMemoryData(
          reg_info, heap_data_up->GetBytes() + data_offset, curr_byte_size,
          byte_order, error);
      if (bytes_copied == 0)
        return false;
      if (bytes_copied >= bytes_left)
        break;
      data_offset += bytes_copied;
      bytes_left -= bytes_copied;
      ++NGRN;
    }
  } else {
    const RegisterInfo *reg_info = nullptr;
    if (is_return_value) {
      // The Darwin arm64 ABI doesn't write the return location back to x8
      // before returning from the function the way the x86_64 ABI does.  So
      // we can't reconstruct stack based returns on exit from the function:
      return false;
    } else {
      // We are assuming we are stopped at the first instruction in a function
      // and that the ABI is being respected so all parameters appear where
      // they should be (functions with no external linkage can legally violate
      // the ABI).
      if (NGRN >= 8)
        return false;
 
      uint32_t reg_num = reg_ctx->ConvertRegisterKindToRegisterNumber(
          eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG1 + NGRN);
      if (reg_num == LLDB_INVALID_REGNUM)
        return false;
      reg_info = reg_ctx->GetRegisterInfoAtIndex(reg_num);
      if (reg_info == nullptr)
        return false;
      ++NGRN;
    }
 
    if (reg_info == nullptr)
      return false;
 
    const lldb::addr_t value_addr =
        reg_ctx->ReadRegisterAsUnsigned(reg_info, LLDB_INVALID_ADDRESS);
 
    if (value_addr == LLDB_INVALID_ADDRESS)
      return false;
 
    if (exe_ctx.GetProcessRef().ReadMemory(
            value_addr, heap_data_up->GetBytes(), heap_data_up->GetByteSize(),
            error) != heap_data_up->GetByteSize()) {
      return false;
    }
  }
 
  data.SetByteOrder(byte_order);
  data.SetAddressByteSize(exe_ctx.GetProcessRef().GetAddressByteSize());
  data.SetData(DataBufferSP(heap_data_up.release()));
  return true;
}
 
ValueObjectSP ABIMacOSX_arm64::GetReturnValueObjectImpl(
    Thread &thread, CompilerType &return_compiler_type) const {
  ValueObjectSP return_valobj_sp;
  Value value;
 
  ExecutionContext exe_ctx(thread.shared_from_this());
  if (exe_ctx.GetTargetPtr() == nullptr || exe_ctx.GetProcessPtr() == nullptr)
    return return_valobj_sp;
 
  // value.SetContext (Value::eContextTypeClangType, return_compiler_type);
  value.SetCompilerType(return_compiler_type);
 
  RegisterContext *reg_ctx = thread.GetRegisterContext().get();
  if (!reg_ctx)
    return return_valobj_sp;
 
  llvm::Optional<uint64_t> byte_size =
      return_compiler_type.GetByteSize(&thread);
  if (!byte_size)
    return return_valobj_sp;
 
  const uint32_t type_flags = return_compiler_type.GetTypeInfo(nullptr);
  if (type_flags & eTypeIsScalar || type_flags & eTypeIsPointer) {
    value.SetValueType(Value::ValueType::Scalar);
 
    bool success = false;
    if (type_flags & eTypeIsInteger || type_flags & eTypeIsPointer) {
      // Extract the register context so we can read arguments from registers
      if (*byte_size <= 8) {
        const RegisterInfo *x0_reg_info =
            reg_ctx->GetRegisterInfoByName("x0", 0);
        if (x0_reg_info) {
          uint64_t raw_value =
              thread.GetRegisterContext()->ReadRegisterAsUnsigned(x0_reg_info,
                                                                  0);
          const bool is_signed = (type_flags & eTypeIsSigned) != 0;
          switch (*byte_size) {
          default:
            break;
          case 16: // uint128_t
            // In register x0 and x1
            {
              const RegisterInfo *x1_reg_info =
                  reg_ctx->GetRegisterInfoByName("x1", 0);
 
              if (x1_reg_info) {
                if (*byte_size <=
                    x0_reg_info->byte_size + x1_reg_info->byte_size) {
                  std::unique_ptr<DataBufferHeap> heap_data_up(
                      new DataBufferHeap(*byte_size, 0));
                  const ByteOrder byte_order =
                      exe_ctx.GetProcessRef().GetByteOrder();
                  RegisterValue x0_reg_value;
                  RegisterValue x1_reg_value;
                  if (reg_ctx->ReadRegister(x0_reg_info, x0_reg_value) &&
                      reg_ctx->ReadRegister(x1_reg_info, x1_reg_value)) {
                    Status error;
                    if (x0_reg_value.GetAsMemoryData(
                            x0_reg_info, heap_data_up->GetBytes() + 0, 8,
                            byte_order, error) &&
                        x1_reg_value.GetAsMemoryData(
                            x1_reg_info, heap_data_up->GetBytes() + 8, 8,
                            byte_order, error)) {
                      DataExtractor data(
                          DataBufferSP(heap_data_up.release()), byte_order,
                          exe_ctx.GetProcessRef().GetAddressByteSize());
 
                      return_valobj_sp = ValueObjectConstResult::Create(
                          &thread, return_compiler_type, ConstString(""), data);
                      return return_valobj_sp;
                    }
                  }
                }
              }
            }
            break;
          case sizeof(uint64_t):
            if (is_signed)
              value.GetScalar() = (int64_t)(raw_value);
            else
              value.GetScalar() = (uint64_t)(raw_value);
            success = true;
            break;
 
          case sizeof(uint32_t):
            if (is_signed)
              value.GetScalar() = (int32_t)(raw_value & UINT32_MAX);
            else
              value.GetScalar() = (uint32_t)(raw_value & UINT32_MAX);
            success = true;
            break;
 
          case sizeof(uint16_t):
            if (is_signed)
              value.GetScalar() = (int16_t)(raw_value & UINT16_MAX);
            else
              value.GetScalar() = (uint16_t)(raw_value & UINT16_MAX);
            success = true;
            break;
 
          case sizeof(uint8_t):
            if (is_signed)
              value.GetScalar() = (int8_t)(raw_value & UINT8_MAX);
            else
              value.GetScalar() = (uint8_t)(raw_value & UINT8_MAX);
            success = true;
            break;
          }
        }
      }
    } else if (type_flags & eTypeIsFloat) {
      if (type_flags & eTypeIsComplex) {
        // Don't handle complex yet.
      } else {
        if (*byte_size <= sizeof(long double)) {
          const RegisterInfo *v0_reg_info =
              reg_ctx->GetRegisterInfoByName("v0", 0);
          RegisterValue v0_value;
          if (reg_ctx->ReadRegister(v0_reg_info, v0_value)) {
            DataExtractor data;
            if (v0_value.GetData(data)) {
              lldb::offset_t offset = 0;
              if (*byte_size == sizeof(float)) {
                value.GetScalar() = data.GetFloat(&offset);
                success = true;
              } else if (*byte_size == sizeof(double)) {
                value.GetScalar() = data.GetDouble(&offset);
                success = true;
              } else if (*byte_size == sizeof(long double)) {
                value.GetScalar() = data.GetLongDouble(&offset);
                success = true;
              }
            }
          }
        }
      }
    }
 
    if (success)
      return_valobj_sp = ValueObjectConstResult::Create(
          thread.GetStackFrameAtIndex(0).get(), value, ConstString(""));
  } else if (type_flags & eTypeIsVector) {
    if (*byte_size > 0) {
 
      const RegisterInfo *v0_info = reg_ctx->GetRegisterInfoByName("v0", 0);
 
      if (v0_info) {
        if (*byte_size <= v0_info->byte_size) {
          std::unique_ptr<DataBufferHeap> heap_data_up(
              new DataBufferHeap(*byte_size, 0));
          const ByteOrder byte_order = exe_ctx.GetProcessRef().GetByteOrder();
          RegisterValue reg_value;
          if (reg_ctx->ReadRegister(v0_info, reg_value)) {
            Status error;
            if (reg_value.GetAsMemoryData(v0_info, heap_data_up->GetBytes(),
                                          heap_data_up->GetByteSize(),
                                          byte_order, error)) {
              DataExtractor data(DataBufferSP(heap_data_up.release()),
                                 byte_order,
                                 exe_ctx.GetProcessRef().GetAddressByteSize());
              return_valobj_sp = ValueObjectConstResult::Create(
                  &thread, return_compiler_type, ConstString(""), data);
            }
          }
        }
      }
    }
  } else if (type_flags & eTypeIsStructUnion || type_flags & eTypeIsClass) {
    DataExtractor data;
 
    uint32_t NGRN = 0; // Search ABI docs for NGRN
    uint32_t NSRN = 0; // Search ABI docs for NSRN
    const bool is_return_value = true;
    if (LoadValueFromConsecutiveGPRRegisters(
            exe_ctx, reg_ctx, return_compiler_type, is_return_value, NGRN, NSRN,
            data)) {
      return_valobj_sp = ValueObjectConstResult::Create(
          &thread, return_compiler_type, ConstString(""), data);
    }
  }
  return return_valobj_sp;
}
 
lldb::addr_t ABIMacOSX_arm64::FixAddress(addr_t pc, addr_t mask) {
  lldb::addr_t pac_sign_extension = 0x0080000000000000ULL;
  // Darwin systems originally couldn't determine the proper value
  // dynamically, so the most common value was hardcoded.  This has
  // largely been cleaned up, but there are still a handful of
  // environments that assume the default value is set to this value
  // and there's no dynamic value to correct it.
  // When no mask is specified, set it to 39 bits of addressing (0..38).
  if (mask == 0) {
    // ~((1ULL<<39)-1)
    mask = 0xffffff8000000000;
  }
  return (pc & pac_sign_extension) ? pc | mask : pc & (~mask);
}
 
void ABIMacOSX_arm64::Initialize() {
  PluginManager::RegisterPlugin(GetPluginNameStatic(), pluginDesc,
                                CreateInstance);
}
 
void ABIMacOSX_arm64::Terminate() {
  PluginManager::UnregisterPlugin(CreateInstance);
}