//===-- ABIMacOSX_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 "ABIMacOSX_i386.h"

#include <optional>

#include <vector>

#include "llvm/ADT/STLExtras.h"

#include "llvm/TargetParser/Triple.h"

#include "lldb/Core/Module.h"

#include "lldb/Core/PluginManager.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/RegisterValue.h"

#include "lldb/Utility/Scalar.h"

#include "lldb/Utility/Status.h"

using namespace lldb;

using namespace lldb_private;

LLDB_PLUGIN_DEFINE(ABIMacOSX_i386)

enum {

  dwarf_eax = 0,

  dwarf_ecx,

  dwarf_edx,

  dwarf_ebx,

  dwarf_esp,

  dwarf_ebp,

  dwarf_esi,

  dwarf_edi,

  dwarf_eip,

};

size_t ABIMacOSX_i386::GetRedZoneSize() const { return 0; }

// Static Functions

ABISP

ABIMacOSX_i386::CreateInstance(lldb::ProcessSP process_sp, const ArchSpec &arch) {

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

      
(34
arch.GetTriple().isMacOSX()34
 || 
arch.GetTriple().isiOS()34
 ||

       arch.GetTriple().isWatchOS())) {

    return ABISP(

        new ABIMacOSX_i386(std::move(process_sp), MakeMCRegisterInfo(arch)));

  }

  return ABISP();

}

bool ABIMacOSX_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);

  // When writing a register value down to memory, the register info used to

  // write memory 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. Here we use "eax"...

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

  if (!reg_info_32)

    return false; // TODO this should actually never happen

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

  Status error;

  RegisterValue reg_value;

  // Write any arguments onto the stack

  sp -= 4 * args.size();

  // Align the SP

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

  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 (yes after we just set the

  // alignment above!).

  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;

  // %esp is set to the actual stack value.

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

    return false;

  // %eip is set 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->ReadScalarIntegerFromMemory(current_stack_argument, byte_size,

                                           is_signed, scalar, error)) {

    current_stack_argument += byte_size;

    return true;

  }

  return false;

}

bool ABIMacOSX_i386::GetArgumentValues(Thread &thread,

                                       ValueList &values) const {

  unsigned int num_values = values.GetSize();

  unsigned int value_index;

  // Get the pointer to the first stack argument so we have a place to start

  // when reading data

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

  if (!reg_ctx)

    return false;

  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;

    // We currently only support extracting values with Clang QualTypes. Do we

    // care about others?

    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 ABIMacOSX_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;

  }

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

  bool is_signed;

  uint32_t count;

  bool is_complex;

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

  bool set_it_simple = false;

  if (compiler_type.IsIntegerOrEnumerationType(is_signed) ||

      compiler_type.IsPointerType()) {

    DataExtractor data;

    Status data_error;

    size_t num_bytes = 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;

    }

    lldb::offset_t offset = 0;

    if (num_bytes <= 8) {

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

      if (num_bytes <= 4) {

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

        if (reg_ctx->WriteRegisterFromUnsigned(eax_info, raw_value))

          set_it_simple = true;

      } else {

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

        if (reg_ctx->WriteRegisterFromUnsigned(eax_info, raw_value)) {

          const RegisterInfo *edx_info =

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

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

          if (reg_ctx->WriteRegisterFromUnsigned(edx_info, raw_value))

            set_it_simple = true;

        }

      }

    } else {

      error.SetErrorString("We don't support returning longer than 64 bit "

                           "integer values at present.");

    }

  } else if (compiler_type.IsFloatingPointType(count, is_complex)) {

    if (is_complex)

      error.SetErrorString(

          "We don't support returning complex values at present");

    else

      error.SetErrorString(

          "We don't support returning float values at present");

  }

  if (!set_it_simple)

    error.SetErrorString(

        "We only support setting simple integer return types at present.");

  return error;

}

ValueObjectSP

ABIMacOSX_i386::GetReturnValueObjectImpl(Thread &thread,

                                         CompilerType &compiler_type) const {

  Value value;

  ValueObjectSP return_valobj_sp;

  if (!compiler_type)

    return return_valobj_sp;

  // value.SetContext (Value::eContextTypeClangType,

  // compiler_type.GetOpaqueQualType());

  value.SetCompilerType(compiler_type);

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

  if (!reg_ctx)

    return return_valobj_sp;

  bool is_signed;

  if (compiler_type.IsIntegerOrEnumerationType(is_signed)) {

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

    if (!bit_width)

      return return_valobj_sp;

    unsigned eax_id =

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

    unsigned edx_id =

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

    switch (*bit_width) {

    default:

    case 128:

      // Scalar can't hold 128-bit literals, so we don't handle this

      return return_valobj_sp;

    case 64:

      uint64_t raw_value;

      raw_value =

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

          0xffffffff;

      raw_value |=

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

           0xffffffff)

          << 32;

      if (is_signed)

        value.GetScalar() = (int64_t)raw_value;

      else

        value.GetScalar() = (uint64_t)raw_value;

      break;

    case 32:

      if (is_signed)

        value.GetScalar() = (int32_t)(

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

            0xffffffff);

      else

        value.GetScalar() = (uint32_t)(

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

            0xffffffff);

      break;

    case 16:

      if (is_signed)

        value.GetScalar() = (int16_t)(

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

            0xffff);

      else

        value.GetScalar() = (uint16_t)(

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

            0xffff);

      break;

    case 8:

      if (is_signed)

        value.GetScalar() = (int8_t)(

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

            0xff);

      else

        value.GetScalar() = (uint8_t)(

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

            0xff);

      break;

    }

  } else if (compiler_type.IsPointerType()) {

    unsigned eax_id =

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

    uint32_t ptr =

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

        0xffffffff;

    value.GetScalar() = ptr;

  } else {

    // not handled yet

    return return_valobj_sp;

  }

  // If we get here, we have a valid Value, so make our ValueObject out of it:

  return_valobj_sp = ValueObjectConstResult::Create(

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

  return return_valobj_sp;

}

// This defines the CFA as esp+4

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

// The saved esp is CFA+0

bool ABIMacOSX_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 the 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 ABIMacOSX_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;

}

bool ABIMacOSX_i386::RegisterIsVolatile(const RegisterInfo *reg_info) {

  return !RegisterIsCalleeSaved(reg_info);

}

// v.

// http://developer.apple.com/library/mac/#documentation/developertools/Conceptual/LowLevelABI/130

// -IA-

// 32_Function_Calling_Conventions/IA32.html#//apple_ref/doc/uid/TP40002492-SW4

//

// This document ("OS X ABI Function Call Guide", chapter "IA-32 Function

// Calling Conventions") says that the following registers on i386 are

// preserved aka non-volatile aka callee-saved:

//

// ebx, ebp, esi, edi, esp

bool ABIMacOSX_i386::RegisterIsCalleeSaved(const RegisterInfo *reg_info) {

  if (reg_info) {

    // 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 ABIMacOSX_i386::Initialize() {

  PluginManager::RegisterPlugin(

      GetPluginNameStatic(), "Mac OS X ABI for i386 targets", CreateInstance);

}

void ABIMacOSX_i386::Terminate() {

  PluginManager::UnregisterPlugin(CreateInstance);

}