//===-- ABISysV_i386.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 "ABISysV_i386.h"

#include "llvm/ADT/STLExtras.h"

#include "llvm/TargetParser/Triple.h"

#include "lldb/Core/Module.h"

#include "lldb/Core/PluginManager.h"

#include "lldb/Core/Value.h"

#include "lldb/Core/ValueObjectConstResult.h"

#include "lldb/Core/ValueObjectMemory.h"

#include "lldb/Core/ValueObjectRegister.h"

#include "lldb/Symbol/UnwindPlan.h"

#include "lldb/Target/Process.h"

#include "lldb/Target/RegisterContext.h"

#include "lldb/Target/StackFrame.h"

#include "lldb/Target/Target.h"

#include "lldb/Target/Thread.h"

#include "lldb/Utility/ConstString.h"

#include "lldb/Utility/DataExtractor.h"

#include "lldb/Utility/Log.h"

#include "lldb/Utility/RegisterValue.h"

#include "lldb/Utility/Status.h"

#include <optional>

using namespace lldb;

using namespace lldb_private;

LLDB_PLUGIN_DEFINE(ABISysV_i386)

//   This source file uses the following document as a reference:

//====================================================================

//             System V Application Binary Interface

//    Intel386 Architecture Processor Supplement, Version 1.0

//                         Edited by

//      H.J. Lu, David L Kreitzer, Milind Girkar, Zia Ansari

//

//                        (Based on

//           System V Application Binary Interface,

//          AMD64 Architecture Processor Supplement,

//                         Edited by

//     H.J. Lu, Michael Matz, Milind Girkar, Jan Hubicka,

//               Andreas Jaeger, Mark Mitchell)

//

//                     February 3, 2015

//====================================================================

// DWARF Register Number Mapping

// See Table 2.14 of the reference document (specified on top of this file)

// Comment: Table 2.14 is followed till 'mm' entries. After that, all entries

// are ignored here.

enum dwarf_regnums {

  dwarf_eax = 0,

  dwarf_ecx,

  dwarf_edx,

  dwarf_ebx,

  dwarf_esp,

  dwarf_ebp,

  dwarf_esi,

  dwarf_edi,

  dwarf_eip,

};

// Static Functions

ABISP

ABISysV_i386::CreateInstance(lldb::ProcessSP process_sp, const ArchSpec &arch) {

  if (arch.GetTriple().getVendor() != llvm::Triple::Apple) {

    if (arch.GetTriple().getArch() == llvm::Triple::x86) {

      return ABISP(

          new ABISysV_i386(std::move(process_sp), MakeMCRegisterInfo(arch)));

    }

  }

  return ABISP();

}

bool ABISysV_i386::PrepareTrivialCall(Thread &thread, addr_t sp,

                                      addr_t func_addr, addr_t return_addr,

                                      llvm::ArrayRef<addr_t> args) const {

  RegisterContext *reg_ctx = thread.GetRegisterContext().get();

  if (!reg_ctx)

    return false;

  uint32_t pc_reg_num = reg_ctx->ConvertRegisterKindToRegisterNumber(

      eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);

  uint32_t sp_reg_num = reg_ctx->ConvertRegisterKindToRegisterNumber(

      eRegisterKindGeneric, LLDB_REGNUM_GENERIC_SP);

  // While using register info to write a register value to memory, the

  // register info just needs to have the correct size of a 32 bit register,

  // the actual register it pertains to is not important, just the size needs

  // to be correct. "eax" is used here for this purpose.

  const RegisterInfo *reg_info_32 = reg_ctx->GetRegisterInfoByName("eax");

  if (!reg_info_32)

    return false; // TODO this should actually never happen

  Status error;

  RegisterValue reg_value;

  // Make room for the argument(s) on the stack

  sp -= 4 * args.size();

  // SP Alignment

  sp &= ~(16ull - 1ull); // 16-byte alignment

  // Write arguments onto the stack

  addr_t arg_pos = sp;

  for (addr_t arg : args) {

    reg_value.SetUInt32(arg);

    error = reg_ctx->WriteRegisterValueToMemory(

        reg_info_32, arg_pos, reg_info_32->byte_size, reg_value);

    if (error.Fail())

      return false;

    arg_pos += 4;

  }

  // The return address is pushed onto the stack

  sp -= 4;

  reg_value.SetUInt32(return_addr);

  error = reg_ctx->WriteRegisterValueToMemory(

      reg_info_32, sp, reg_info_32->byte_size, reg_value);

  if (error.Fail())

    return false;

  // Setting %esp to the actual stack value.

  if (!reg_ctx->WriteRegisterFromUnsigned(sp_reg_num, sp))

    return false;

  // Setting %eip to the address of the called function.

  if (!reg_ctx->WriteRegisterFromUnsigned(pc_reg_num, func_addr))

    return false;

  return true;

}

static bool ReadIntegerArgument(Scalar &scalar, unsigned int bit_width,

                                bool is_signed, Process *process,

                                addr_t &current_stack_argument) {

  uint32_t byte_size = (bit_width + (8 - 1)) / 8;

  Status error;

  if (!process)

    return false;

  if (process->ReadScalarIntegerFromMemory(current_stack_argument, byte_size,

                                           is_signed, scalar, error)) {

    current_stack_argument += byte_size;

    return true;

  }

  return false;

}

bool ABISysV_i386::GetArgumentValues(Thread &thread, ValueList &values) const {

  unsigned int num_values = values.GetSize();

  unsigned int value_index;

  RegisterContext *reg_ctx = thread.GetRegisterContext().get();

  if (!reg_ctx)

    return false;

  // Get pointer to the first stack argument

  addr_t sp = reg_ctx->GetSP(0);

  if (!sp)

    return false;

  addr_t current_stack_argument = sp + 4; // jump over return address

  for (value_index = 0; value_index < num_values; ++value_index) {

    Value *value = values.GetValueAtIndex(value_index);

    if (!value)

      return false;

    // Currently: Support for extracting values with Clang QualTypes only.

    CompilerType compiler_type(value->GetCompilerType());

    std::optional<uint64_t> bit_size = compiler_type.GetBitSize(&thread);

    if (bit_size) {

      bool is_signed;

      if (compiler_type.IsIntegerOrEnumerationType(is_signed)) {

        ReadIntegerArgument(value->GetScalar(), *bit_size, is_signed,

                            thread.GetProcess().get(), current_stack_argument);

      } else if (compiler_type.IsPointerType()) {

        ReadIntegerArgument(value->GetScalar(), *bit_size, false,

                            thread.GetProcess().get(), current_stack_argument);

      }

    }

  }

  return true;

}

Status ABISysV_i386::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 compiler_type = new_value_sp->GetCompilerType();

  if (!compiler_type) {

    error.SetErrorString("Null clang type for return value.");

    return error;

  }

  const uint32_t type_flags = compiler_type.GetTypeInfo();

  Thread *thread = frame_sp->GetThread().get();

  RegisterContext *reg_ctx = thread->GetRegisterContext().get();

  DataExtractor data;

  Status data_error;

  size_t num_bytes = new_value_sp->GetData(data, data_error);

  bool register_write_successful = true;

  if (data_error.Fail()) {

    error.SetErrorStringWithFormat(

        "Couldn't convert return value to raw data: %s",

        data_error.AsCString());

    return error;

  }

  // Following "IF ELSE" block categorizes various 'Fundamental Data Types'.

  // The terminology 'Fundamental Data Types' used here is adopted from Table

  // 2.1 of the reference document (specified on top of this file)

  if (type_flags & eTypeIsPointer) // 'Pointer'

  {

    if (num_bytes != sizeof(uint32_t)) {

      error.SetErrorString("Pointer to be returned is not 4 bytes wide");

      return error;

    }

    lldb::offset_t offset = 0;

    const RegisterInfo *eax_info = reg_ctx->GetRegisterInfoByName("eax", 0);

    uint32_t raw_value = data.GetMaxU32(&offset, num_bytes);

    register_write_successful =

        reg_ctx->WriteRegisterFromUnsigned(eax_info, raw_value);

  } else if ((type_flags & eTypeIsScalar) ||

             (type_flags & eTypeIsEnumeration)) //'Integral' + 'Floating Point'

  {

    lldb::offset_t offset = 0;

    const RegisterInfo *eax_info = reg_ctx->GetRegisterInfoByName("eax", 0);

    if (type_flags & eTypeIsInteger) // 'Integral' except enum

    {

      switch (num_bytes) {

      default:

        break;

      case 16:

        // For clang::BuiltinType::UInt128 & Int128 ToDo: Need to decide how to

        // handle it

        break;

      case 8: {

        uint32_t raw_value_low = data.GetMaxU32(&offset, 4);

        const RegisterInfo *edx_info = reg_ctx->GetRegisterInfoByName("edx", 0);

        uint32_t raw_value_high = data.GetMaxU32(&offset, num_bytes - offset);

        register_write_successful =

            (reg_ctx->WriteRegisterFromUnsigned(eax_info, raw_value_low) &&

             reg_ctx->WriteRegisterFromUnsigned(edx_info, raw_value_high));

        break;

      }

      case 4:

      case 2:

      case 1: {

        uint32_t raw_value = data.GetMaxU32(&offset, num_bytes);

        register_write_successful =

            reg_ctx->WriteRegisterFromUnsigned(eax_info, raw_value);

        break;

      }

      }

    } else if (type_flags & eTypeIsEnumeration) // handles enum

    {

      uint32_t raw_value = data.GetMaxU32(&offset, num_bytes);

      register_write_successful =

          reg_ctx->WriteRegisterFromUnsigned(eax_info, raw_value);

    } else if (type_flags & eTypeIsFloat) // 'Floating Point'

    {

      RegisterValue st0_value, fstat_value, ftag_value;

      const RegisterInfo *st0_info = reg_ctx->GetRegisterInfoByName("st0", 0);

      const RegisterInfo *fstat_info =

          reg_ctx->GetRegisterInfoByName("fstat", 0);

      const RegisterInfo *ftag_info = reg_ctx->GetRegisterInfoByName("ftag", 0);

      /* According to Page 3-12 of document

      System V Application Binary Interface, Intel386 Architecture Processor

      Supplement, Fourth Edition

      To return Floating Point values, all st% registers except st0 should be

      empty after exiting from

      a function. This requires setting fstat and ftag registers to specific

      values.

      fstat: The TOP field of fstat should be set to a value [0,7]. ABI doesn't

      specify the specific

      value of TOP in case of function return. Hence, we set the TOP field to 7

      by our choice. */

      uint32_t value_fstat_u32 = 0x00003800;

      /* ftag: Implication of setting TOP to 7 and indicating all st% registers

      empty except st0 is to set

      7th bit of 4th byte of FXSAVE area to 1 and all other bits of this byte to

      0. This is in accordance

      with the document Intel 64 and IA-32 Architectures Software Developer's

      Manual, January 2015 */

      uint32_t value_ftag_u32 = 0x00000080;

      if (num_bytes <= 12) // handles float, double, long double, __float80

      {

        long double value_long_dbl = 0.0;

        if (num_bytes == 4)

          value_long_dbl = data.GetFloat(&offset);

        else if (num_bytes == 8)

          value_long_dbl = data.GetDouble(&offset);

        else if (num_bytes == 12)

          value_long_dbl = data.GetLongDouble(&offset);

        else {

          error.SetErrorString("Invalid number of bytes for this return type");

          return error;

        }

        st0_value.SetLongDouble(value_long_dbl);

        fstat_value.SetUInt32(value_fstat_u32);

        ftag_value.SetUInt32(value_ftag_u32);

        register_write_successful =

            reg_ctx->WriteRegister(st0_info, st0_value) &&

            reg_ctx->WriteRegister(fstat_info, fstat_value) &&

            reg_ctx->WriteRegister(ftag_info, ftag_value);

      } else if (num_bytes == 16) // handles __float128

      {

        error.SetErrorString("Implementation is missing for this clang type.");

      }

    } else {

      // Neither 'Integral' nor 'Floating Point'. If flow reaches here then

      // check type_flags. This type_flags is not a valid type.

      error.SetErrorString("Invalid clang type");

    }

  } else {

    /* 'Complex Floating Point', 'Packed', 'Decimal Floating Point' and

    'Aggregate' data types

    are yet to be implemented */

    error.SetErrorString("Currently only Integral and Floating Point clang "

                         "types are supported.");

  }

  if (!register_write_successful)

    error.SetErrorString("Register writing failed");

  return error;

}

ValueObjectSP ABISysV_i386::GetReturnValueObjectSimple(

    Thread &thread, CompilerType &return_compiler_type) const {

  ValueObjectSP return_valobj_sp;

  Value value;

  if (!return_compiler_type)

    return return_valobj_sp;

  value.SetCompilerType(return_compiler_type);

  RegisterContext *reg_ctx = thread.GetRegisterContext().get();

  if (!reg_ctx)

    return return_valobj_sp;

  const uint32_t type_flags = return_compiler_type.GetTypeInfo();

  unsigned eax_id =

      reg_ctx->GetRegisterInfoByName("eax", 0)->kinds[eRegisterKindLLDB];

  unsigned edx_id =

      reg_ctx->GetRegisterInfoByName("edx", 0)->kinds[eRegisterKindLLDB];

  // Following "IF ELSE" block categorizes various 'Fundamental Data Types'.

  // The terminology 'Fundamental Data Types' used here is adopted from Table

  // 2.1 of the reference document (specified on top of this file)

  if (type_flags & eTypeIsPointer) // 'Pointer'

  {

    uint32_t ptr =

        thread.GetRegisterContext()->ReadRegisterAsUnsigned(eax_id, 0) &

        0xffffffff;

    value.SetValueType(Value::ValueType::Scalar);

    value.GetScalar() = ptr;

    return_valobj_sp = ValueObjectConstResult::Create(

        thread.GetStackFrameAtIndex(0).get(), value, ConstString(""));

  } else if ((type_flags & eTypeIsScalar) ||

             (type_flags & eTypeIsEnumeration)) //'Integral' + 'Floating Point'

  {

    value.SetValueType(Value::ValueType::Scalar);

    std::optional<uint64_t> byte_size =

        return_compiler_type.GetByteSize(&thread);

    if (!byte_size)

      return return_valobj_sp;

    bool success = false;

    if (type_flags & eTypeIsInteger) // 'Integral' except enum

    {

      const bool is_signed = ((type_flags & eTypeIsSigned) != 0);

      uint64_t raw_value =

          thread.GetRegisterContext()->ReadRegisterAsUnsigned(eax_id, 0) &

          0xffffffff;

      raw_value |=

          (thread.GetRegisterContext()->ReadRegisterAsUnsigned(edx_id, 0) &

           0xffffffff)

          << 32;

      switch (*byte_size) {

      default:

        break;

      case 16:

        // For clang::BuiltinType::UInt128 & Int128 ToDo: Need to decide how to

        // handle it

        break;

      case 8:

        if (is_signed)

          value.GetScalar() = (int64_t)(raw_value);

        else

          value.GetScalar() = (uint64_t)(raw_value);

        success = true;

        break;

      case 4:

        if (is_signed)

          value.GetScalar() = (int32_t)(raw_value & UINT32_MAX);

        else

          value.GetScalar() = (uint32_t)(raw_value & UINT32_MAX);

        success = true;

        break;

      case 2:

        if (is_signed)

          value.GetScalar() = (int16_t)(raw_value & UINT16_MAX);

        else

          value.GetScalar() = (uint16_t)(raw_value & UINT16_MAX);

        success = true;

        break;

      case 1:

        if (is_signed)

          value.GetScalar() = (int8_t)(raw_value & UINT8_MAX);

        else

          value.GetScalar() = (uint8_t)(raw_value & UINT8_MAX);

        success = true;

        break;

      }

      if (success)

        return_valobj_sp = ValueObjectConstResult::Create(

            thread.GetStackFrameAtIndex(0).get(), value, ConstString(""));

    } else if (type_flags & eTypeIsEnumeration) // handles enum

    {

      uint32_t enm =

          thread.GetRegisterContext()->ReadRegisterAsUnsigned(eax_id, 0) &

          0xffffffff;

      value.SetValueType(Value::ValueType::Scalar);

      value.GetScalar() = enm;

      return_valobj_sp = ValueObjectConstResult::Create(

          thread.GetStackFrameAtIndex(0).get(), value, ConstString(""));

    } else if (type_flags & eTypeIsFloat) // 'Floating Point'

    {

      if (*byte_size <= 12) // handles float, double, long double, __float80

      {

        const RegisterInfo *st0_info = reg_ctx->GetRegisterInfoByName("st0", 0);

        RegisterValue st0_value;

        if (reg_ctx->ReadRegister(st0_info, st0_value)) {

          DataExtractor data;

          if (st0_value.GetData(data)) {

            lldb::offset_t offset = 0;

            long double value_long_double = data.GetLongDouble(&offset);

            // float is 4 bytes.

            if (*byte_size == 4) {

              float value_float = (float)value_long_double;

              value.GetScalar() = value_float;

              success = true;

            } else if (*byte_size == 8) {

              // double is 8 bytes

              // On Android Platform: long double is also 8 bytes It will be

              // handled here only.

              double value_double = (double)value_long_double;

              value.GetScalar() = value_double;

              success = true;

            } else if (*byte_size == 12) {

              // long double and __float80 are 12 bytes on i386.

              value.GetScalar() = value_long_double;

              success = true;

            }

          }

        }

        if (success)

          return_valobj_sp = ValueObjectConstResult::Create(

              thread.GetStackFrameAtIndex(0).get(), value, ConstString(""));

      } else if (*byte_size == 16) // handles __float128

      {

        lldb::addr_t storage_addr = (uint32_t)(

            thread.GetRegisterContext()->ReadRegisterAsUnsigned(eax_id, 0) &

            0xffffffff);

        return_valobj_sp = ValueObjectMemory::Create(

            &thread, "", Address(storage_addr, nullptr), return_compiler_type);

      }

    } else // Neither 'Integral' nor 'Floating Point'

    {

      // If flow reaches here then check type_flags This type_flags is

      // unhandled

    }

  } else if (type_flags & eTypeIsComplex) // 'Complex Floating Point'

  {

    // ToDo: Yet to be implemented

  } else if (type_flags & eTypeIsVector) // 'Packed'

  {

    std::optional<uint64_t> byte_size =

        return_compiler_type.GetByteSize(&thread);

    if (byte_size && *byte_size > 0) {

      const RegisterInfo *vec_reg = reg_ctx->GetRegisterInfoByName("xmm0", 0);

      if (vec_reg == nullptr)

        vec_reg = reg_ctx->GetRegisterInfoByName("mm0", 0);

      if (vec_reg) {

        if (*byte_size <= vec_reg->byte_size) {

          ProcessSP process_sp(thread.GetProcess());

          if (process_sp) {

            std::unique_ptr<DataBufferHeap> heap_data_up(

                new DataBufferHeap(*byte_size, 0));

            const ByteOrder byte_order = process_sp->GetByteOrder();

            RegisterValue reg_value;

            if (reg_ctx->ReadRegister(vec_reg, reg_value)) {

              Status error;

              if (reg_value.GetAsMemoryData(*vec_reg, heap_data_up->GetBytes(),

                                            heap_data_up->GetByteSize(),

                                            byte_order, error)) {

                DataExtractor data(DataBufferSP(heap_data_up.release()),

                                   byte_order,

                                   process_sp->GetTarget()

                                       .GetArchitecture()

                                       .GetAddressByteSize());

                return_valobj_sp = ValueObjectConstResult::Create(

                    &thread, return_compiler_type, ConstString(""), data);

              }

            }

          }

        } else if (*byte_size <= vec_reg->byte_size * 2) {

          const RegisterInfo *vec_reg2 =

              reg_ctx->GetRegisterInfoByName("xmm1", 0);

          if (vec_reg2) {

            ProcessSP process_sp(thread.GetProcess());

            if (process_sp) {

              std::unique_ptr<DataBufferHeap> heap_data_up(

                  new DataBufferHeap(*byte_size, 0));

              const ByteOrder byte_order = process_sp->GetByteOrder();

              RegisterValue reg_value;

              RegisterValue reg_value2;

              if (reg_ctx->ReadRegister(vec_reg, reg_value) &&

                  reg_ctx->ReadRegister(vec_reg2, reg_value2)) {

                Status error;

                if (reg_value.GetAsMemoryData(

                        *vec_reg, heap_data_up->GetBytes(), vec_reg->byte_size,

                        byte_order, error) &&

                    reg_value2.GetAsMemoryData(

                        *vec_reg2,

                        heap_data_up->GetBytes() + vec_reg->byte_size,

                        heap_data_up->GetByteSize() - vec_reg->byte_size,

                        byte_order, error)) {

                  DataExtractor data(DataBufferSP(heap_data_up.release()),

                                     byte_order,

                                     process_sp->GetTarget()

                                         .GetArchitecture()

                                         .GetAddressByteSize());

                  return_valobj_sp = ValueObjectConstResult::Create(

                      &thread, return_compiler_type, ConstString(""), data);

                }

              }

            }

          }

        }

      }

    }

  } else // 'Decimal Floating Point'

  {

    // ToDo: Yet to be implemented

  }

  return return_valobj_sp;

}

ValueObjectSP ABISysV_i386::GetReturnValueObjectImpl(

    Thread &thread, CompilerType &return_compiler_type) const {

  ValueObjectSP return_valobj_sp;

  if (!return_compiler_type)

    return return_valobj_sp;

  ExecutionContext exe_ctx(thread.shared_from_this());

  return_valobj_sp = GetReturnValueObjectSimple(thread, return_compiler_type);

  if (return_valobj_sp)

    return return_valobj_sp;

  RegisterContextSP reg_ctx_sp = thread.GetRegisterContext();

  if (!reg_ctx_sp)

    return return_valobj_sp;

  if (return_compiler_type.IsAggregateType()) {

    unsigned eax_id =

        reg_ctx_sp->GetRegisterInfoByName("eax", 0)->kinds[eRegisterKindLLDB];

    lldb::addr_t storage_addr = (uint32_t)(

        thread.GetRegisterContext()->ReadRegisterAsUnsigned(eax_id, 0) &

        0xffffffff);

    return_valobj_sp = ValueObjectMemory::Create(

        &thread, "", Address(storage_addr, nullptr), return_compiler_type);

  }

  return return_valobj_sp;

}

// This defines CFA as esp+4

// The saved pc is at CFA-4 (i.e. esp+0)

// The saved esp is CFA+0

bool ABISysV_i386::CreateFunctionEntryUnwindPlan(UnwindPlan &unwind_plan) {

  unwind_plan.Clear();

  unwind_plan.SetRegisterKind(eRegisterKindDWARF);

  uint32_t sp_reg_num = dwarf_esp;

  uint32_t pc_reg_num = dwarf_eip;

  UnwindPlan::RowSP row(new UnwindPlan::Row);

  row->GetCFAValue().SetIsRegisterPlusOffset(sp_reg_num, 4);

  row->SetRegisterLocationToAtCFAPlusOffset(pc_reg_num, -4, false);

  row->SetRegisterLocationToIsCFAPlusOffset(sp_reg_num, 0, true);

  unwind_plan.AppendRow(row);

  unwind_plan.SetSourceName("i386 at-func-entry default");

  unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);

  return true;

}

// This defines CFA as ebp+8

// The saved pc is at CFA-4 (i.e. ebp+4)

// The saved ebp is at CFA-8 (i.e. ebp+0)

// The saved esp is CFA+0

bool ABISysV_i386::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {

  unwind_plan.Clear();

  unwind_plan.SetRegisterKind(eRegisterKindDWARF);

  uint32_t fp_reg_num = dwarf_ebp;

  uint32_t sp_reg_num = dwarf_esp;

  uint32_t pc_reg_num = dwarf_eip;

  UnwindPlan::RowSP row(new UnwindPlan::Row);

  const int32_t ptr_size = 4;

  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);

  row->SetRegisterLocationToIsCFAPlusOffset(sp_reg_num, 0, true);

  unwind_plan.AppendRow(row);

  unwind_plan.SetSourceName("i386 default unwind plan");

  unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);

  unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);

  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);

  return true;

}

// According to "Register Usage" in reference document (specified on top of

// this source file) ebx, ebp, esi, edi and esp registers are preserved i.e.

// non-volatile i.e. callee-saved on i386

bool ABISysV_i386::RegisterIsCalleeSaved(const RegisterInfo *reg_info) {

  if (!reg_info)

    return false;

  // Saved registers are ebx, ebp, esi, edi, esp, eip

  const char *name = reg_info->name;

  if (name[0] == 'e') {

    switch (name[1]) {

    case 'b':

      if (name[2] == 'x' || name[2] == 'p')

        return name[3] == '\0';

      break;

    case 'd':

      if (name[2] == 'i')

        return name[3] == '\0';

      break;

    case 'i':

      if (name[2] == 'p')

        return name[3] == '\0';

      break;

    case 's':

      if (name[2] == 'i' || name[2] == 'p')

        return name[3] == '\0';

      break;

    }

  }

  if (name[0] == 's' && name[1] == 'p' && name[2] == '\0') // sp

    return true;

  if (name[0] == 'f' && name[1] == 'p' && name[2] == '\0') // fp

    return true;

  if (name[0] == 'p' && name[1] == 'c' && name[2] == '\0') // pc

    return true;

  return false;

}

void ABISysV_i386::Initialize() {

  PluginManager::RegisterPlugin(

      GetPluginNameStatic(), "System V ABI for i386 targets", CreateInstance);

}

void ABISysV_i386::Terminate() {

  PluginManager::UnregisterPlugin(CreateInstance);

}