//===-- UnwindAssemblyInstEmulation.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 "UnwindAssemblyInstEmulation.h"

#include "lldb/Core/Address.h"

#include "lldb/Core/Disassembler.h"

#include "lldb/Core/DumpDataExtractor.h"

#include "lldb/Core/DumpRegisterValue.h"

#include "lldb/Core/FormatEntity.h"

#include "lldb/Core/PluginManager.h"

#include "lldb/Target/ExecutionContext.h"

#include "lldb/Target/Process.h"

#include "lldb/Target/Target.h"

#include "lldb/Target/Thread.h"

#include "lldb/Utility/ArchSpec.h"

#include "lldb/Utility/DataBufferHeap.h"

#include "lldb/Utility/DataExtractor.h"

#include "lldb/Utility/LLDBLog.h"

#include "lldb/Utility/Log.h"

#include "lldb/Utility/Status.h"

#include "lldb/Utility/StreamString.h"

using namespace lldb;

using namespace lldb_private;

LLDB_PLUGIN_DEFINE(UnwindAssemblyInstEmulation)

//  UnwindAssemblyInstEmulation method definitions

bool UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly(

    AddressRange &range, Thread &thread, UnwindPlan &unwind_plan) {

  std::vector<uint8_t> function_text(range.GetByteSize());

  ProcessSP process_sp(thread.GetProcess());

  if (process_sp) {

    Status error;

    const bool force_live_memory = true;

    if (process_sp->GetTarget().ReadMemory(

            range.GetBaseAddress(), function_text.data(), range.GetByteSize(),

            error, force_live_memory) != range.GetByteSize()) {

      return false;

    }

  }

  return GetNonCallSiteUnwindPlanFromAssembly(

      range, function_text.data(), function_text.size(), unwind_plan);

}

bool UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly(

    AddressRange &range, uint8_t *opcode_data, size_t opcode_size,

    UnwindPlan &unwind_plan) {

  if (opcode_data == nullptr || opcode_size == 0)

    return false;

  if (range.GetByteSize() > 0 && range.GetBaseAddress().IsValid() &&

      m_inst_emulator_up.get()) {

    // The instruction emulation subclass setup the unwind plan for the first

    // instruction.

    m_inst_emulator_up->CreateFunctionEntryUnwind(unwind_plan);

    // CreateFunctionEntryUnwind should have created the first row. If it

    // doesn't, then we are done.

    if (unwind_plan.GetRowCount() == 0)

      return false;

    const bool prefer_file_cache = true;

    DisassemblerSP disasm_sp(Disassembler::DisassembleBytes(

        m_arch, nullptr, nullptr, range.GetBaseAddress(), opcode_data,

        opcode_size, 99999, prefer_file_cache));

    Log *log = GetLog(LLDBLog::Unwind);

    if (disasm_sp) {

      m_range_ptr = ⦥

      m_unwind_plan_ptr = &unwind_plan;

      const uint32_t addr_byte_size = m_arch.GetAddressByteSize();

      const bool show_address = true;

      const bool show_bytes = true;

      const bool show_control_flow_kind = true;

      m_cfa_reg_info = *m_inst_emulator_up->GetRegisterInfo(

          unwind_plan.GetRegisterKind(), unwind_plan.GetInitialCFARegister());

      m_fp_is_cfa = false;

      m_register_values.clear();

      m_pushed_regs.clear();

      // Initialize the CFA with a known value. In the 32 bit case it will be

      // 0x80000000, and in the 64 bit case 0x8000000000000000. We use the

      // address byte size to be safe for any future address sizes

      m_initial_sp = (1ull << ((addr_byte_size * 8) - 1));

      RegisterValue cfa_reg_value;

      cfa_reg_value.SetUInt(m_initial_sp, m_cfa_reg_info.byte_size);

      SetRegisterValue(m_cfa_reg_info, cfa_reg_value);

      const InstructionList &inst_list = disasm_sp->GetInstructionList();

      const size_t num_instructions = inst_list.GetSize();

      if (num_instructions > 0) {

        Instruction *inst = inst_list.GetInstructionAtIndex(0).get();

        const lldb::addr_t base_addr = inst->GetAddress().GetFileAddress();

        // Map for storing the unwind plan row and the value of the registers

        // at a given offset. When we see a forward branch we add a new entry

        // to this map with the actual unwind plan row and register context for

        // the target address of the branch as the current data have to be

        // valid for the target address of the branch too if we are in the same

        // function.

        std::map<lldb::addr_t, std::pair<UnwindPlan::RowSP, RegisterValueMap>>

            saved_unwind_states;

        // Make a copy of the current instruction Row and save it in m_curr_row

        // so we can add updates as we process the instructions.

        UnwindPlan::RowSP last_row = unwind_plan.GetLastRow();

        UnwindPlan::Row *newrow = new UnwindPlan::Row;

        if (last_row.get())

          *newrow = *last_row.get();

        m_curr_row.reset(newrow);

        // Add the initial state to the save list with offset 0.

        saved_unwind_states.insert({0, {last_row, m_register_values}});

        // cache the stack pointer register number (in whatever register

        // numbering this UnwindPlan uses) for quick reference during

        // instruction parsing.

        RegisterInfo sp_reg_info = *m_inst_emulator_up->GetRegisterInfo(

            eRegisterKindGeneric, LLDB_REGNUM_GENERIC_SP);

        // The architecture dependent condition code of the last processed

        // instruction.

        EmulateInstruction::InstructionCondition last_condition =

            EmulateInstruction::UnconditionalCondition;

        lldb::addr_t condition_block_start_offset = 0;

        for (size_t idx = 0; idx < num_instructions; 
++idx149
) {

          m_curr_row_modified = false;

          m_forward_branch_offset = 0;

          inst = inst_list.GetInstructionAtIndex(idx).get();

          if (inst) {

            lldb::addr_t current_offset =

                inst->GetAddress().GetFileAddress() - base_addr;

            auto it = saved_unwind_states.upper_bound(current_offset);

            assert(it != saved_unwind_states.begin() &&

                   "Unwind row for the function entry missing");

            --it; // Move it to the row corresponding to the current offset

            // If the offset of m_curr_row don't match with the offset we see

            // in saved_unwind_states then we have to update m_curr_row and

            // m_register_values based on the saved values. It is happening

            // after we processed an epilogue and a return to caller

            // instruction.

            if (it->second.first->GetOffset() != m_curr_row->GetOffset()) {

              UnwindPlan::Row *newrow = new UnwindPlan::Row;

              *newrow = *it->second.first;

              m_curr_row.reset(newrow);

              m_register_values = it->second.second;

              // re-set the CFA register ivars to match the

              // new m_curr_row.

              if (sp_reg_info.name &&

                  m_curr_row->GetCFAValue().IsRegisterPlusOffset()) {

                uint32_t row_cfa_regnum =

                    m_curr_row->GetCFAValue().GetRegisterNumber();

                lldb::RegisterKind row_kind =

                    m_unwind_plan_ptr->GetRegisterKind();

                // set m_cfa_reg_info to the row's CFA reg.

                m_cfa_reg_info = *m_inst_emulator_up->GetRegisterInfo(

                    row_kind, row_cfa_regnum);

                // set m_fp_is_cfa.

                if (sp_reg_info.kinds[row_kind] == row_cfa_regnum)

                  m_fp_is_cfa = false;

                else

                  m_fp_is_cfa = true;

              }

            }

            m_inst_emulator_up->SetInstruction(inst->GetOpcode(),

                                               inst->GetAddress(), nullptr);

            if (last_condition !=

                m_inst_emulator_up->GetInstructionCondition()) {

              if (m_inst_emulator_up->GetInstructionCondition() !=

                      EmulateInstruction::UnconditionalCondition &&

                  saved_unwind_states.count(current_offset) == 0) {

                // If we don't have a saved row for the current offset then

                // save our current state because we will have to restore it

                // after the conditional block.

                auto new_row =

                    std::make_shared<UnwindPlan::Row>(*m_curr_row.get());

                saved_unwind_states.insert(

                    {current_offset, {new_row, m_register_values}});

              }

              // If the last instruction was conditional with a different

              // condition then the then current condition then restore the

              // condition.

              if (last_condition !=

                  EmulateInstruction::UnconditionalCondition) {

                const auto &saved_state =

                    saved_unwind_states.at(condition_block_start_offset);

                m_curr_row =

                    std::make_shared<UnwindPlan::Row>(*saved_state.first);

                m_curr_row->SetOffset(current_offset);

                m_register_values = saved_state.second;

                // re-set the CFA register ivars to match the

                // new m_curr_row.

                if (sp_reg_info.name &&

                    m_curr_row->GetCFAValue().IsRegisterPlusOffset()) {

                  uint32_t row_cfa_regnum =

                      m_curr_row->GetCFAValue().GetRegisterNumber();

                  lldb::RegisterKind row_kind =

                      m_unwind_plan_ptr->GetRegisterKind();

                  // set m_cfa_reg_info to the row's CFA reg.

                  m_cfa_reg_info = *m_inst_emulator_up->GetRegisterInfo(

                      row_kind, row_cfa_regnum);

                  // set m_fp_is_cfa.

                  if (sp_reg_info.kinds[row_kind] == row_cfa_regnum)

                    m_fp_is_cfa = false;

                  else

                    m_fp_is_cfa = true;

                }

                bool replace_existing =

                    true; // The last instruction might already

                          // created a row for this offset and

                          // we want to overwrite it.

                unwind_plan.InsertRow(

                    std::make_shared<UnwindPlan::Row>(*m_curr_row),

                    replace_existing);

              }

              // We are starting a new conditional block at the actual offset

              condition_block_start_offset = current_offset;

            }

            if (log && 
log->GetVerbose()0
) {

              StreamString strm;

              lldb_private::FormatEntity::Entry format;

              FormatEntity::Parse("${frame.pc}: ", format);

              inst->Dump(&strm, inst_list.GetMaxOpcocdeByteSize(), show_address,

                         show_bytes, show_control_flow_kind, nullptr, nullptr,

                         nullptr, &format, 0);

              log->PutString(strm.GetString());

            }

            last_condition = m_inst_emulator_up->GetInstructionCondition();

            m_inst_emulator_up->EvaluateInstruction(

                eEmulateInstructionOptionIgnoreConditions);

            // If the current instruction is a branch forward then save the

            // current CFI information for the offset where we are branching.

            if (m_forward_branch_offset != 0 &&

                range.ContainsFileAddress(inst->GetAddress().GetFileAddress() +

                                          m_forward_branch_offset)) {

              auto newrow =

                  std::make_shared<UnwindPlan::Row>(*m_curr_row.get());

              newrow->SetOffset(current_offset + m_forward_branch_offset);

              saved_unwind_states.insert(

                  {current_offset + m_forward_branch_offset,

                   {newrow, m_register_values}});

              unwind_plan.InsertRow(newrow);

            }

            // Were there any changes to the CFI while evaluating this

            // instruction?

            if (m_curr_row_modified) {

              // Save the modified row if we don't already have a CFI row in

              // the current address

              if (saved_unwind_states.count(

                      current_offset + inst->GetOpcode().GetByteSize()) == 0) {

                m_curr_row->SetOffset(current_offset +

                                      inst->GetOpcode().GetByteSize());

                unwind_plan.InsertRow(m_curr_row);

                saved_unwind_states.insert(

                    {current_offset + inst->GetOpcode().GetByteSize(),

                     {m_curr_row, m_register_values}});

                // Allocate a new Row for m_curr_row, copy the current state

                // into it

                UnwindPlan::Row *newrow = new UnwindPlan::Row;

                *newrow = *m_curr_row.get();

                m_curr_row.reset(newrow);

              }

            }

          }

        }

      }

    }

    if (log && 
log->GetVerbose()0
) {

      StreamString strm;

      lldb::addr_t base_addr = range.GetBaseAddress().GetFileAddress();

      strm.Printf("Resulting unwind rows for [0x%" PRIx64 " - 0x%" PRIx64 "):",

                  base_addr, base_addr + range.GetByteSize());

      unwind_plan.Dump(strm, nullptr, base_addr);

      log->PutString(strm.GetString());

    }

    return unwind_plan.GetRowCount() > 0;

  }

  return false;

}

bool UnwindAssemblyInstEmulation::AugmentUnwindPlanFromCallSite(

    AddressRange &func, Thread &thread, UnwindPlan &unwind_plan) {

  return false;

}

bool UnwindAssemblyInstEmulation::GetFastUnwindPlan(AddressRange &func,

                                                    Thread &thread,

                                                    UnwindPlan &unwind_plan) {

  return false;

}

bool UnwindAssemblyInstEmulation::FirstNonPrologueInsn(

    AddressRange &func, const ExecutionContext &exe_ctx,

    Address &first_non_prologue_insn) {

  return false;

}

UnwindAssembly *

UnwindAssemblyInstEmulation::CreateInstance(const ArchSpec &arch) {

  std::unique_ptr<EmulateInstruction> inst_emulator_up(

      EmulateInstruction::FindPlugin(arch, eInstructionTypePrologueEpilogue,

                                     nullptr));

  // Make sure that all prologue instructions are handled

  if (inst_emulator_up)

    return new UnwindAssemblyInstEmulation(arch, inst_emulator_up.release());

  return nullptr;

}

void UnwindAssemblyInstEmulation::Initialize() {

  PluginManager::RegisterPlugin(GetPluginNameStatic(),

                                GetPluginDescriptionStatic(), CreateInstance);

}

void UnwindAssemblyInstEmulation::Terminate() {

  PluginManager::UnregisterPlugin(CreateInstance);

}

llvm::StringRef UnwindAssemblyInstEmulation::GetPluginDescriptionStatic() {

  return "Instruction emulation based unwind information.";

}

uint64_t UnwindAssemblyInstEmulation::MakeRegisterKindValuePair(

    const RegisterInfo &reg_info) {

  lldb::RegisterKind reg_kind;

  uint32_t reg_num;

  if (EmulateInstruction::GetBestRegisterKindAndNumber(&reg_info, reg_kind,

                                                       reg_num))

    return (uint64_t)reg_kind << 24 | reg_num;

  return 0ull;

}

void UnwindAssemblyInstEmulation::SetRegisterValue(

    const RegisterInfo &reg_info, const RegisterValue &reg_value) {

  m_register_values[MakeRegisterKindValuePair(reg_info)] = reg_value;

}

bool UnwindAssemblyInstEmulation::GetRegisterValue(const RegisterInfo &reg_info,

                                                   RegisterValue &reg_value) {

  const uint64_t reg_id = MakeRegisterKindValuePair(reg_info);

  RegisterValueMap::const_iterator pos = m_register_values.find(reg_id);

  if (pos != m_register_values.end()) {

    reg_value = pos->second;

    return true; // We had a real value that comes from an opcode that wrote

                 // to it...

  }

  // We are making up a value that is recognizable...

  reg_value.SetUInt(reg_id, reg_info.byte_size);

  return false;

}

size_t UnwindAssemblyInstEmulation::ReadMemory(

    EmulateInstruction *instruction, void *baton,

    const EmulateInstruction::Context &context, lldb::addr_t addr, void *dst,

    size_t dst_len) {

  Log *log = GetLog(LLDBLog::Unwind);

  if (log && 
log->GetVerbose()0
) {

    StreamString strm;

    strm.Printf(

        "UnwindAssemblyInstEmulation::ReadMemory    (addr = 0x%16.16" PRIx64

        ", dst = %p, dst_len = %" PRIu64 ", context = ",

        addr, dst, (uint64_t)dst_len);

    context.Dump(strm, instruction);

    log->PutString(strm.GetString());

  }

  memset(dst, 0, dst_len);

  return dst_len;

}

size_t UnwindAssemblyInstEmulation::WriteMemory(

    EmulateInstruction *instruction, void *baton,

    const EmulateInstruction::Context &context, lldb::addr_t addr,

    const void *dst, size_t dst_len) {

  if (baton && dst && dst_len)

    return ((UnwindAssemblyInstEmulation *)baton)

        ->WriteMemory(instruction, context, addr, dst, dst_len);

  return 0;

}

size_t UnwindAssemblyInstEmulation::WriteMemory(

    EmulateInstruction *instruction, const EmulateInstruction::Context &context,

    lldb::addr_t addr, const void *dst, size_t dst_len) {

  DataExtractor data(dst, dst_len,

                     instruction->GetArchitecture().GetByteOrder(),

                     instruction->GetArchitecture().GetAddressByteSize());

  Log *log = GetLog(LLDBLog::Unwind);

  if (log && 
log->GetVerbose()0
) {

    StreamString strm;

    strm.PutCString("UnwindAssemblyInstEmulation::WriteMemory   (");

    DumpDataExtractor(data, &strm, 0, eFormatBytes, 1, dst_len, UINT32_MAX,

                      addr, 0, 0);

    strm.PutCString(", context = ");

    context.Dump(strm, instruction);

    log->PutString(strm.GetString());

  }

  const bool cant_replace = false;

  switch (context.type) {

  default:

  case EmulateInstruction::eContextInvalid:

  case EmulateInstruction::eContextReadOpcode:

  case EmulateInstruction::eContextImmediate:

  case EmulateInstruction::eContextAdjustBaseRegister:

  case EmulateInstruction::eContextRegisterPlusOffset:

  case EmulateInstruction::eContextAdjustPC:

  case EmulateInstruction::eContextRegisterStore:

  case EmulateInstruction::eContextRegisterLoad:

  case EmulateInstruction::eContextRelativeBranchImmediate:

  case EmulateInstruction::eContextAbsoluteBranchRegister:

  case EmulateInstruction::eContextSupervisorCall:

  case EmulateInstruction::eContextTableBranchReadMemory:

  case EmulateInstruction::eContextWriteRegisterRandomBits:

  case EmulateInstruction::eContextWriteMemoryRandomBits:

  case EmulateInstruction::eContextArithmetic:

  case EmulateInstruction::eContextAdvancePC:

  case EmulateInstruction::eContextReturnFromException:

  case EmulateInstruction::eContextPopRegisterOffStack:

  case EmulateInstruction::eContextAdjustStackPointer:

    break;

  case EmulateInstruction::eContextPushRegisterOnStack: {

    uint32_t reg_num = LLDB_INVALID_REGNUM;

    uint32_t generic_regnum = LLDB_INVALID_REGNUM;

    assert(context.GetInfoType() ==

               EmulateInstruction::eInfoTypeRegisterToRegisterPlusOffset &&

           "unhandled case, add code to handle this!");

    const uint32_t unwind_reg_kind = m_unwind_plan_ptr->GetRegisterKind();

    reg_num = context.info.RegisterToRegisterPlusOffset.data_reg

                  .kinds[unwind_reg_kind];

    generic_regnum = context.info.RegisterToRegisterPlusOffset.data_reg

                         .kinds[eRegisterKindGeneric];

    if (reg_num != LLDB_INVALID_REGNUM &&

        generic_regnum != LLDB_REGNUM_GENERIC_SP) {

      if (m_pushed_regs.find(reg_num) == m_pushed_regs.end()) {

        m_pushed_regs[reg_num] = addr;

        const int32_t offset = addr - m_initial_sp;

        m_curr_row->SetRegisterLocationToAtCFAPlusOffset(reg_num, offset,

                                                         cant_replace);

        m_curr_row_modified = true;

      }

    }

  } break;

  }

  return dst_len;

}

bool UnwindAssemblyInstEmulation::ReadRegister(EmulateInstruction *instruction,

                                               void *baton,

                                               const RegisterInfo *reg_info,

                                               RegisterValue &reg_value) {

  if (baton && reg_info)

    return ((UnwindAssemblyInstEmulation *)baton)

        ->ReadRegister(instruction, reg_info, reg_value);

  return false;

}

bool UnwindAssemblyInstEmulation::ReadRegister(EmulateInstruction *instruction,

                                               const RegisterInfo *reg_info,

                                               RegisterValue &reg_value) {

  bool synthetic = GetRegisterValue(*reg_info, reg_value);

  Log *log = GetLog(LLDBLog::Unwind);

  if (log && 
log->GetVerbose()0
) {

    StreamString strm;

    strm.Printf("UnwindAssemblyInstEmulation::ReadRegister  (name = \"%s\") => "

                "synthetic_value = %i, value = ",

                reg_info->name, synthetic);

    DumpRegisterValue(reg_value, strm, *reg_info, false, false, eFormatDefault);

    log->PutString(strm.GetString());

  }

  return true;

}

bool UnwindAssemblyInstEmulation::WriteRegister(

    EmulateInstruction *instruction, void *baton,

    const EmulateInstruction::Context &context, const RegisterInfo *reg_info,

    const RegisterValue &reg_value) {

  if (baton && reg_info)

    return ((UnwindAssemblyInstEmulation *)baton)

        ->WriteRegister(instruction, context, reg_info, reg_value);

  return false;

}

bool UnwindAssemblyInstEmulation::WriteRegister(

    EmulateInstruction *instruction, const EmulateInstruction::Context &context,

    const RegisterInfo *reg_info, const RegisterValue &reg_value) {

  Log *log = GetLog(LLDBLog::Unwind);

  if (log && 
log->GetVerbose()0
) {

    StreamString strm;

    strm.Printf(

        "UnwindAssemblyInstEmulation::WriteRegister (name = \"%s\", value = ",

        reg_info->name);

    DumpRegisterValue(reg_value, strm, *reg_info, false, false, eFormatDefault);

    strm.PutCString(", context = ");

    context.Dump(strm, instruction);

    log->PutString(strm.GetString());

  }

  SetRegisterValue(*reg_info, reg_value);

  switch (context.type) {

  case EmulateInstruction::eContextInvalid:

  case EmulateInstruction::eContextReadOpcode:

  case EmulateInstruction::eContextImmediate:

  case EmulateInstruction::eContextAdjustBaseRegister:

  case EmulateInstruction::eContextRegisterPlusOffset:

  case EmulateInstruction::eContextAdjustPC:

  case EmulateInstruction::eContextRegisterStore:

  case EmulateInstruction::eContextSupervisorCall:

  case EmulateInstruction::eContextTableBranchReadMemory:

  case EmulateInstruction::eContextWriteRegisterRandomBits:

  case EmulateInstruction::eContextWriteMemoryRandomBits:

  case EmulateInstruction::eContextAdvancePC:

  case EmulateInstruction::eContextReturnFromException:

  case EmulateInstruction::eContextPushRegisterOnStack:

  case EmulateInstruction::eContextRegisterLoad:

    //            {

    //                const uint32_t reg_num =

    //                reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()];

    //                if (reg_num != LLDB_INVALID_REGNUM)

    //                {

    //                    const bool can_replace_only_if_unspecified = true;

    //

    //                    m_curr_row.SetRegisterLocationToUndefined (reg_num,

    //                                                               can_replace_only_if_unspecified,

    //                                                               can_replace_only_if_unspecified);

    //                    m_curr_row_modified = true;

    //                }

    //            }

    break;

  case EmulateInstruction::eContextArithmetic: {

    // If we adjusted the current frame pointer by a constant then adjust the

    // CFA offset

    // with the same amount.

    lldb::RegisterKind kind = m_unwind_plan_ptr->GetRegisterKind();

    if (m_fp_is_cfa && reg_info->kinds[kind] == m_cfa_reg_info.kinds[kind] &&

        context.GetInfoType() ==

            EmulateInstruction::eInfoTypeRegisterPlusOffset &&

        context.info.RegisterPlusOffset.reg.kinds[kind] ==

            m_cfa_reg_info.kinds[kind]) {

      const int64_t offset = context.info.RegisterPlusOffset.signed_offset;

      m_curr_row->GetCFAValue().IncOffset(-1 * offset);

      m_curr_row_modified = true;

    }

  } break;

  case EmulateInstruction::eContextAbsoluteBranchRegister:

  case EmulateInstruction::eContextRelativeBranchImmediate: {

    if (context.GetInfoType() == EmulateInstruction::eInfoTypeISAAndImmediate &&

        
context.info.ISAAndImmediate.unsigned_data32 > 00
) {

      m_forward_branch_offset =

          context.info.ISAAndImmediateSigned.signed_data32;

    } else if (context.GetInfoType() ==

                   EmulateInstruction::eInfoTypeISAAndImmediateSigned &&

               
context.info.ISAAndImmediateSigned.signed_data32 > 02
) {

      m_forward_branch_offset = context.info.ISAAndImmediate.unsigned_data32;

    } else if (context.GetInfoType() ==

                   EmulateInstruction::eInfoTypeImmediate &&

               
context.info.unsigned_immediate > 00
) {

      m_forward_branch_offset = context.info.unsigned_immediate;

    } else if (context.GetInfoType() ==

                   EmulateInstruction::eInfoTypeImmediateSigned &&

               context.info.signed_immediate > 0) {

      m_forward_branch_offset = context.info.signed_immediate;

    }

  } break;

  case EmulateInstruction::eContextPopRegisterOffStack: {

    const uint32_t reg_num =

        reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()];

    const uint32_t generic_regnum = reg_info->kinds[eRegisterKindGeneric];

    if (reg_num != LLDB_INVALID_REGNUM &&

        generic_regnum != LLDB_REGNUM_GENERIC_SP) {

      switch (context.GetInfoType()) {

      case EmulateInstruction::eInfoTypeAddress:

        if (m_pushed_regs.find(reg_num) != m_pushed_regs.end() &&

            
context.info.address == m_pushed_regs[reg_num]48
) {

          m_curr_row->SetRegisterLocationToSame(reg_num,

                                                false /*must_replace*/);

          m_curr_row_modified = true;

          // FP has been restored to its original value, we are back

          // to using SP to calculate the CFA.

          if (m_fp_is_cfa) {

            m_fp_is_cfa = false;

            lldb::RegisterKind sp_reg_kind = eRegisterKindGeneric;

            uint32_t sp_reg_num = LLDB_REGNUM_GENERIC_SP;

            RegisterInfo sp_reg_info =

                *m_inst_emulator_up->GetRegisterInfo(sp_reg_kind, sp_reg_num);

            RegisterValue sp_reg_val;

            if (GetRegisterValue(sp_reg_info, sp_reg_val)) {

              m_cfa_reg_info = sp_reg_info;

              const uint32_t cfa_reg_num =

                  sp_reg_info.kinds[m_unwind_plan_ptr->GetRegisterKind()];

              assert(cfa_reg_num != LLDB_INVALID_REGNUM);

              m_curr_row->GetCFAValue().SetIsRegisterPlusOffset(

                  cfa_reg_num, m_initial_sp - sp_reg_val.GetAsUInt64());

            }

          }

        }

        break;

      case EmulateInstruction::eInfoTypeISA:

        assert(

            (generic_regnum == LLDB_REGNUM_GENERIC_PC ||

             generic_regnum == LLDB_REGNUM_GENERIC_FLAGS) &&

            "eInfoTypeISA used for popping a register other the PC/FLAGS");

        if (generic_regnum != LLDB_REGNUM_GENERIC_FLAGS) {

          m_curr_row->SetRegisterLocationToSame(reg_num,

                                                false /*must_replace*/);

          m_curr_row_modified = true;

        }

        break;

      default:

        assert(false && "unhandled case, add code to handle this!");

        break;

      }

    }

  } break;

  case EmulateInstruction::eContextSetFramePointer:

    if (!m_fp_is_cfa) {

      m_fp_is_cfa = true;

      m_cfa_reg_info = *reg_info;

      const uint32_t cfa_reg_num =

          reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()];

      assert(cfa_reg_num != LLDB_INVALID_REGNUM);

      m_curr_row->GetCFAValue().SetIsRegisterPlusOffset(

          cfa_reg_num, m_initial_sp - reg_value.GetAsUInt64());

      m_curr_row_modified = true;

    }

    break;

  case EmulateInstruction::eContextRestoreStackPointer:

    if (m_fp_is_cfa) {

      m_fp_is_cfa = false;

      m_cfa_reg_info = *reg_info;

      const uint32_t cfa_reg_num =

          reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()];

      assert(cfa_reg_num != LLDB_INVALID_REGNUM);

      m_curr_row->GetCFAValue().SetIsRegisterPlusOffset(

          cfa_reg_num, m_initial_sp - reg_value.GetAsUInt64());

      m_curr_row_modified = true;

    }

    break;

  case EmulateInstruction::eContextAdjustStackPointer:

    // If we have created a frame using the frame pointer, don't follow

    // subsequent adjustments to the stack pointer.

    if (!m_fp_is_cfa) {

      m_curr_row->GetCFAValue().SetIsRegisterPlusOffset(

          m_curr_row->GetCFAValue().GetRegisterNumber(),

          m_initial_sp - reg_value.GetAsUInt64());

      m_curr_row_modified = true;

    }

    break;

  }

  return true;

}