xref: /llvm-project-15.0.7/lldb/source/Core/Disassembler.cpp (revision de2fb9cf)

//===-- Disassembler.cpp ----------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "lldb/Core/Disassembler.h"

// C Includes
// C++ Includes
// Other libraries and framework includes
// Project includes
#include "lldb/lldb-private.h"
#include "lldb/Core/Error.h"
#include "lldb/Core/DataBufferHeap.h"
#include "lldb/Core/DataExtractor.h"
#include "lldb/Core/Debugger.h"
#include "lldb/Core/EmulateInstruction.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/RegularExpression.h"
#include "lldb/Core/Timer.h"
#include "lldb/Interpreter/NamedOptionValue.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/StackFrame.h"
#include "lldb/Target/Target.h"

#define DEFAULT_DISASM_BYTE_SIZE 32

using namespace lldb;
using namespace lldb_private;


Disassembler*
Disassembler::FindPlugin (const ArchSpec &arch, const char *plugin_name)
{
    Timer scoped_timer (__PRETTY_FUNCTION__,
                        "Disassembler::FindPlugin (arch = %s, plugin_name = %s)",
                        arch.GetArchitectureName(),
                        plugin_name);

    std::auto_ptr<Disassembler> disassembler_ap;
    DisassemblerCreateInstance create_callback = NULL;

    if (plugin_name)
    {
        create_callback = PluginManager::GetDisassemblerCreateCallbackForPluginName (plugin_name);
        if (create_callback)
        {
            disassembler_ap.reset (create_callback(arch));

            if (disassembler_ap.get())
                return disassembler_ap.release();
        }
    }
    else
    {
        for (uint32_t idx = 0; (create_callback = PluginManager::GetDisassemblerCreateCallbackAtIndex(idx)) != NULL; ++idx)
        {
            disassembler_ap.reset (create_callback(arch));

            if (disassembler_ap.get())
                return disassembler_ap.release();
        }
    }
    return NULL;
}


static void
ResolveAddress (const ExecutionContext &exe_ctx,
                const Address &addr,
                Address &resolved_addr)
{
    if (!addr.IsSectionOffset())
    {
        // If we weren't passed in a section offset address range,
        // try and resolve it to something
        if (exe_ctx.target)
        {
            if (exe_ctx.target->GetSectionLoadList().IsEmpty())
            {
                exe_ctx.target->GetImages().ResolveFileAddress (addr.GetOffset(), resolved_addr);
            }
            else
            {
                exe_ctx.target->GetSectionLoadList().ResolveLoadAddress (addr.GetOffset(), resolved_addr);
            }
            // We weren't able to resolve the address, just treat it as a
            // raw address
            if (resolved_addr.IsValid())
                return;
        }
    }
    resolved_addr = addr;
}

size_t
Disassembler::Disassemble
(
    Debugger &debugger,
    const ArchSpec &arch,
    const char *plugin_name,
    const ExecutionContext &exe_ctx,
    SymbolContextList &sc_list,
    uint32_t num_instructions,
    uint32_t num_mixed_context_lines,
    bool show_bytes,
    bool raw,
    Stream &strm
)
{
    size_t success_count = 0;
    const size_t count = sc_list.GetSize();
    SymbolContext sc;
    AddressRange range;

    for (size_t i=0; i<count; ++i)
    {
        if (sc_list.GetContextAtIndex(i, sc) == false)
            break;
        if (sc.GetAddressRange(eSymbolContextFunction | eSymbolContextSymbol, range))
        {
            if (Disassemble (debugger,
                             arch,
                             plugin_name,
                             exe_ctx,
                             range,
                             num_instructions,
                             num_mixed_context_lines,
                             show_bytes,
                             raw,
                             strm))
            {
                ++success_count;
                strm.EOL();
            }
        }
    }
    return success_count;
}

bool
Disassembler::Disassemble
(
    Debugger &debugger,
    const ArchSpec &arch,
    const char *plugin_name,
    const ExecutionContext &exe_ctx,
    const ConstString &name,
    Module *module,
    uint32_t num_instructions,
    uint32_t num_mixed_context_lines,
    bool show_bytes,
    bool raw,
    Stream &strm
)
{
    SymbolContextList sc_list;
    if (name)
    {
        const bool include_symbols = true;
        if (module)
        {
            module->FindFunctions (name,
                                   eFunctionNameTypeBase |
                                   eFunctionNameTypeFull |
                                   eFunctionNameTypeMethod |
                                   eFunctionNameTypeSelector,
                                   include_symbols,
                                   true,
                                   sc_list);
        }
        else if (exe_ctx.target)
        {
            exe_ctx.target->GetImages().FindFunctions (name,
                                                       eFunctionNameTypeBase |
                                                       eFunctionNameTypeFull |
                                                       eFunctionNameTypeMethod |
                                                       eFunctionNameTypeSelector,
                                                       include_symbols,
                                                       false,
                                                       sc_list);
        }
    }

    if (sc_list.GetSize ())
    {
        return Disassemble (debugger,
                            arch,
                            plugin_name,
                            exe_ctx,
                            sc_list,
                            num_instructions,
                            num_mixed_context_lines,
                            show_bytes,
                            raw,
                            strm);
    }
    return false;
}


lldb::DisassemblerSP
Disassembler::DisassembleRange
(
    const ArchSpec &arch,
    const char *plugin_name,
    const ExecutionContext &exe_ctx,
    const AddressRange &range
)
{
    lldb::DisassemblerSP disasm_sp;
    if (range.GetByteSize() > 0 && range.GetBaseAddress().IsValid())
    {
        disasm_sp.reset (Disassembler::FindPlugin(arch, plugin_name));

        if (disasm_sp)
        {
            size_t bytes_disassembled = disasm_sp->ParseInstructions (&exe_ctx, range);
            if (bytes_disassembled == 0)
                disasm_sp.reset();
        }
    }
    return disasm_sp;
}


bool
Disassembler::Disassemble
(
    Debugger &debugger,
    const ArchSpec &arch,
    const char *plugin_name,
    const ExecutionContext &exe_ctx,
    const AddressRange &disasm_range,
    uint32_t num_instructions,
    uint32_t num_mixed_context_lines,
    bool show_bytes,
    bool raw,
    Stream &strm
)
{
    if (disasm_range.GetByteSize())
    {
        std::auto_ptr<Disassembler> disasm_ap (Disassembler::FindPlugin(arch, plugin_name));

        if (disasm_ap.get())
        {
            AddressRange range;
            ResolveAddress (exe_ctx, disasm_range.GetBaseAddress(), range.GetBaseAddress());
            range.SetByteSize (disasm_range.GetByteSize());

            size_t bytes_disassembled = disasm_ap->ParseInstructions (&exe_ctx, range);
            if (bytes_disassembled == 0)
                return false;

            return PrintInstructions (disasm_ap.get(),
                                      debugger,
                                      arch,
                                      exe_ctx,
                                      num_instructions,
                                      num_mixed_context_lines,
                                      show_bytes,
                                      raw,
                                      strm);
        }
    }
    return false;
}

bool
Disassembler::Disassemble
(
    Debugger &debugger,
    const ArchSpec &arch,
    const char *plugin_name,
    const ExecutionContext &exe_ctx,
    const Address &start_address,
    uint32_t num_instructions,
    uint32_t num_mixed_context_lines,
    bool show_bytes,
    bool raw,
    Stream &strm
)
{
    if (num_instructions > 0)
    {
        std::auto_ptr<Disassembler> disasm_ap (Disassembler::FindPlugin(arch, plugin_name));
        if (disasm_ap.get())
        {
            Address addr;
            ResolveAddress (exe_ctx, start_address, addr);

            size_t bytes_disassembled = disasm_ap->ParseInstructions (&exe_ctx, addr, num_instructions);
            if (bytes_disassembled == 0)
                return false;
            return PrintInstructions (disasm_ap.get(),
                                      debugger,
                                      arch,
                                      exe_ctx,
                                      num_instructions,
                                      num_mixed_context_lines,
                                      show_bytes,
                                      raw,
                                      strm);
        }
    }
    return false;
}

bool
Disassembler::PrintInstructions
(
    Disassembler *disasm_ptr,
    Debugger &debugger,
    const ArchSpec &arch,
    const ExecutionContext &exe_ctx,
    uint32_t num_instructions,
    uint32_t num_mixed_context_lines,
    bool show_bytes,
    bool raw,
    Stream &strm
)
{
    // We got some things disassembled...
    size_t num_instructions_found = disasm_ptr->GetInstructionList().GetSize();

    if (num_instructions > 0 && num_instructions < num_instructions_found)
        num_instructions_found = num_instructions;

    const uint32_t max_opcode_byte_size = disasm_ptr->GetInstructionList().GetMaxOpcocdeByteSize ();
    uint32_t offset = 0;
    SymbolContext sc;
    SymbolContext prev_sc;
    AddressRange sc_range;
    Address *pc_addr_ptr = NULL;
    if (exe_ctx.frame)
        pc_addr_ptr = &exe_ctx.frame->GetFrameCodeAddress();

    for (size_t i=0; i<num_instructions_found; ++i)
    {
        Instruction *inst = disasm_ptr->GetInstructionList().GetInstructionAtIndex (i).get();
        if (inst)
        {
            const Address &addr = inst->GetAddress();
            const bool inst_is_at_pc = pc_addr_ptr && addr == *pc_addr_ptr;

            prev_sc = sc;

            Module *module = addr.GetModule();
            if (module)
            {
                uint32_t resolved_mask = module->ResolveSymbolContextForAddress(addr, eSymbolContextEverything, sc);
                if (resolved_mask)
                {
                    if (num_mixed_context_lines)
                    {
                        if (!sc_range.ContainsFileAddress (addr))
                        {
                            sc.GetAddressRange (eSymbolContextEverything, sc_range);

                            if (sc != prev_sc)
                            {
                                if (offset != 0)
                                    strm.EOL();

                                sc.DumpStopContext(&strm, exe_ctx.process, addr, false, true, false);
                                strm.EOL();

                                if (sc.comp_unit && sc.line_entry.IsValid())
                                {
                                    debugger.GetSourceManager().DisplaySourceLinesWithLineNumbers (sc.line_entry.file,
                                                                                                   sc.line_entry.line,
                                                                                                   num_mixed_context_lines,
                                                                                                   num_mixed_context_lines,
                                                                                                   num_mixed_context_lines ? "->" : "",
                                                                                                   &strm);
                                }
                            }
                        }
                    }
                    else if (!(prev_sc.function == sc.function || prev_sc.symbol == sc.symbol))
                    {
                        if (prev_sc.function || prev_sc.symbol)
                            strm.EOL();

                        strm << sc.module_sp->GetFileSpec().GetFilename();

                        if (sc.function)
                            strm << '`' << sc.function->GetMangled().GetName();
                        else if (sc.symbol)
                            strm << '`' << sc.symbol->GetMangled().GetName();
                        strm << ":\n";
                    }
                }
                else
                {
                    sc.Clear();
                }
            }

            if (pc_addr_ptr)
            {
                if (inst_is_at_pc)
                    strm.PutCString("-> ");
                else
                    strm.PutCString("   ");
            }
            inst->Dump(&strm, max_opcode_byte_size, true, show_bytes, &exe_ctx, raw);
            strm.EOL();
        }
        else
        {
            break;
        }
    }

    return true;
}


bool
Disassembler::Disassemble
(
    Debugger &debugger,
    const ArchSpec &arch,
    const char *plugin_name,
    const ExecutionContext &exe_ctx,
    uint32_t num_instructions,
    uint32_t num_mixed_context_lines,
    bool show_bytes,
    bool raw,
    Stream &strm
)
{
    AddressRange range;
    if (exe_ctx.frame)
    {
        SymbolContext sc(exe_ctx.frame->GetSymbolContext(eSymbolContextFunction | eSymbolContextSymbol));
        if (sc.function)
        {
            range = sc.function->GetAddressRange();
        }
        else if (sc.symbol && sc.symbol->GetAddressRangePtr())
        {
            range = *sc.symbol->GetAddressRangePtr();
        }
        else
        {
            range.GetBaseAddress() = exe_ctx.frame->GetFrameCodeAddress();
        }

        if (range.GetBaseAddress().IsValid() && range.GetByteSize() == 0)
            range.SetByteSize (DEFAULT_DISASM_BYTE_SIZE);
    }

    return Disassemble (debugger,
                        arch,
                        plugin_name,
                        exe_ctx,
                        range,
                        num_instructions,
                        num_mixed_context_lines,
                        show_bytes,
                        raw,
                        strm);
}

Instruction::Instruction(const Address &address, AddressClass addr_class) :
    m_address (address),
    m_address_class (addr_class),
    m_opcode()
{
}

Instruction::~Instruction()
{
}

AddressClass
Instruction::GetAddressClass ()
{
    if (m_address_class == eAddressClassInvalid)
        m_address_class = m_address.GetAddressClass();
    return m_address_class;
}

bool
Instruction::DumpEmulation (const ArchSpec &arch)
{
	std::auto_ptr<EmulateInstruction> insn_emulator_ap (EmulateInstruction::FindPlugin (arch, NULL));
	if (insn_emulator_ap.get())
	{
        insn_emulator_ap->SetInstruction (GetOpcode(), GetAddress());
        return insn_emulator_ap->EvaluateInstruction ();
	}

    return false;
}

OptionValueSP
Instruction::ReadArray (FILE *in_file, Stream *out_stream, OptionValue::Type data_type)
{
    bool done = false;
    char buffer[1024];

    OptionValueSP option_value_sp (new OptionValueArray (1u << data_type));

    int idx = 0;
    while (!done)
    {
        if (!fgets (buffer, 1023, in_file))
        {
            out_stream->Printf ("Instruction::ReadArray:  Erroe reading file (fgets).\n");
            option_value_sp.reset ();
            return option_value_sp;
        }

        std::string line (buffer);

        int len = line.size();
        if (line[len-1] == '\n')
        {
            line[len-1] = '\0';
            line.resize (len-1);
        }

        if ((line.size() == 1) && line[0] == ']')
        {
            done = true;
            line.clear();
        }

        if (line.size() > 0)
        {
            std::string value;
            RegularExpression reg_exp ("^[ \t]*([^ \t]+)[ \t]*$");
            bool reg_exp_success = reg_exp.Execute (line.c_str(), 1);
            if (reg_exp_success)
                reg_exp.GetMatchAtIndex (line.c_str(), 1, value);
            else
                value = line;

            OptionValueSP data_value_sp;
            switch (data_type)
            {
            case OptionValue::eTypeUInt64:
                data_value_sp.reset (new OptionValueUInt64 (0, 0));
                data_value_sp->SetValueFromCString (value.c_str());
                break;
            // Other types can be added later as needed.
            default:
                data_value_sp.reset (new OptionValueString (value.c_str(), ""));
                break;
            }

            option_value_sp->GetAsArrayValue()->InsertValue (idx, data_value_sp);
            ++idx;
        }
    }

    return option_value_sp;
}

OptionValueSP
Instruction::ReadDictionary (FILE *in_file, Stream *out_stream)
{
    bool done = false;
    char buffer[1024];

    OptionValueSP option_value_sp (new OptionValueDictionary());
    static ConstString encoding_key ("data_encoding");
    OptionValue::Type data_type = OptionValue::eTypeInvalid;


    while (!done)
    {
        // Read the next line in the file
        if (!fgets (buffer, 1023, in_file))
        {
            out_stream->Printf ("Instruction::ReadDictionary: Error reading file (fgets).\n");
            option_value_sp.reset ();
            return option_value_sp;
        }

        // Check to see if the line contains the end-of-dictionary marker ("}")
        std::string line (buffer);

        int len = line.size();
        if (line[len-1] == '\n')
        {
            line[len-1] = '\0';
            line.resize (len-1);
        }

        if ((line.size() == 1) && (line[0] == '}'))
        {
            done = true;
            line.clear();
        }

        // Try to find a key-value pair in the current line and add it to the dictionary.
        if (line.size() > 0)
        {
            RegularExpression reg_exp ("^[ \t]*([a-zA-Z_][a-zA-Z0-9_]*)[ \t]*=[ \t]*(.*)[ \t]*$");
            bool reg_exp_success = reg_exp.Execute (line.c_str(), 2);
            std::string key;
            std::string value;
            if (reg_exp_success)
            {
                reg_exp.GetMatchAtIndex (line.c_str(), 1, key);
                reg_exp.GetMatchAtIndex (line.c_str(), 2, value);
            }
            else
            {
                out_stream->Printf ("Instruction::ReadDictionary: Failure executing regular expression.\n");
                option_value_sp.reset();
                return option_value_sp;
            }

            ConstString const_key (key.c_str());
            // Check value to see if it's the start of an array or dictionary.

            lldb::OptionValueSP value_sp;
            assert (value.empty() == false);
            assert (key.empty() == false);

            if (value[0] == '{')
            {
                assert (value.size() == 1);
                // value is a dictionary
                value_sp = ReadDictionary (in_file, out_stream);
                if (value_sp.get() == NULL)
                {
                    option_value_sp.reset ();
                    return option_value_sp;
                }
            }
            else if (value[0] == '[')
            {
                assert (value.size() == 1);
                // value is an array
                value_sp = ReadArray (in_file, out_stream, data_type);
                if (value_sp.get() == NULL)
                {
                    option_value_sp.reset ();
                    return option_value_sp;
                }
                // We've used the data_type to read an array; re-set the type to Invalid
                data_type = OptionValue::eTypeInvalid;
            }
            else if ((value[0] == '0') && (value[1] == 'x'))
            {
                value_sp.reset (new OptionValueUInt64 (0, 0));
                value_sp->SetValueFromCString (value.c_str());
            }
            else
            {
                int len = value.size();
                if ((value[0] == '"') && (value[len-1] == '"'))
                    value = value.substr (1, len-2);
                value_sp.reset (new OptionValueString (value.c_str(), ""));
            }



            if (const_key == encoding_key)
            {
                // A 'data_encoding=..." is NOT a normal key-value pair; it is meta-data indicating the
                // data type of an upcoming array (usually the next bit of data to be read in).
                if (strcmp (value.c_str(), "uint32_t") == 0)
                    data_type = OptionValue::eTypeUInt64;
            }
            else
                option_value_sp->GetAsDictionaryValue()->SetValueForKey (const_key, value_sp, false);
        }
    }

    return option_value_sp;
}

bool
Instruction::TestEmulation (Stream *out_stream, const char *file_name)
{
    if (!out_stream)
        return false;

    if (!file_name)
    {
        out_stream->Printf ("Instruction::TestEmulation:  Missing file_name.");
        return false;
    }

    FILE *test_file = fopen (file_name, "r");
    if (!test_file)
    {
        out_stream->Printf ("Instruction::TestEmulation: Attempt to open test file failed.");
        return false;
    }

    char buffer[256];
    if (!fgets (buffer, 255, test_file))
    {
        out_stream->Printf ("Instruction::TestEmulation: Error reading first line of test file.\n");
        fclose (test_file);
        return false;
    }

    if (strncmp (buffer, "InstructionEmulationState={", 27) != 0)
    {
        out_stream->Printf ("Instructin::TestEmulation: Test file does not contain emulation state dictionary\n");
        fclose (test_file);
        return false;
    }

    // Read all the test information from the test file into an OptionValueDictionary.

    OptionValueSP data_dictionary_sp (ReadDictionary (test_file, out_stream));
    if (data_dictionary_sp.get() == NULL)
    {
        out_stream->Printf ("Instruction::TestEmulation:  Error reading Dictionary Object.\n");
        fclose (test_file);
        return false;
    }

    fclose (test_file);

    OptionValueDictionary *data_dictionary = data_dictionary_sp->GetAsDictionaryValue();
    static ConstString description_key ("assembly_string");
    static ConstString triple_key ("triple");

    OptionValueSP value_sp = data_dictionary->GetValueForKey (description_key);

    if (value_sp.get() == NULL)
    {
        out_stream->Printf ("Instruction::TestEmulation:  Test file does not contain description string.\n");
        return false;
    }

    SetDescription (value_sp->GetStringValue());


    value_sp = data_dictionary->GetValueForKey (triple_key);
    if (value_sp.get() == NULL)
    {
        out_stream->Printf ("Instruction::TestEmulation: Test file does not contain triple.\n");
        return false;
    }

    ArchSpec arch;
    arch.SetTriple (llvm::Triple (value_sp->GetStringValue()));

    bool success = false;
    std::auto_ptr<EmulateInstruction> insn_emulator_ap (EmulateInstruction::FindPlugin (arch, NULL));
    if (insn_emulator_ap.get())
        success = insn_emulator_ap->TestEmulation (out_stream, arch, data_dictionary);

    if (success)
        out_stream->Printf ("Emulation test succeeded.");
    else
        out_stream->Printf ("Emulation test failed.");

    return success;
}

bool
Instruction::Emulate (const ArchSpec &arch,
                      bool auto_advance_pc,
                      void *baton,
                      EmulateInstruction::ReadMemory read_mem_callback,
                      EmulateInstruction::WriteMemory write_mem_callback,
                      EmulateInstruction::ReadRegister read_reg_callback,
                      EmulateInstruction::WriteRegister write_reg_callback)
{
	std::auto_ptr<EmulateInstruction> insn_emulator_ap (EmulateInstruction::FindPlugin (arch, NULL));
	if (insn_emulator_ap.get())
	{
		insn_emulator_ap->SetBaton (baton);
		insn_emulator_ap->SetCallbacks (read_mem_callback, write_mem_callback, read_reg_callback, write_reg_callback);
        insn_emulator_ap->SetInstruction (GetOpcode(), GetAddress());
        insn_emulator_ap->SetAdvancePC (auto_advance_pc);
        return insn_emulator_ap->EvaluateInstruction ();
	}

    return false;
}

InstructionList::InstructionList() :
    m_instructions()
{
}

InstructionList::~InstructionList()
{
}

size_t
InstructionList::GetSize() const
{
    return m_instructions.size();
}

uint32_t
InstructionList::GetMaxOpcocdeByteSize () const
{
    uint32_t max_inst_size = 0;
    collection::const_iterator pos, end;
    for (pos = m_instructions.begin(), end = m_instructions.end();
         pos != end;
         ++pos)
    {
        uint32_t inst_size = (*pos)->GetOpcode().GetByteSize();
        if (max_inst_size < inst_size)
            max_inst_size = inst_size;
    }
    return max_inst_size;
}



InstructionSP
InstructionList::GetInstructionAtIndex (uint32_t idx) const
{
    InstructionSP inst_sp;
    if (idx < m_instructions.size())
        inst_sp = m_instructions[idx];
    return inst_sp;
}

void
InstructionList::Clear()
{
  m_instructions.clear();
}

void
InstructionList::Append (lldb::InstructionSP &inst_sp)
{
    if (inst_sp)
        m_instructions.push_back(inst_sp);
}


size_t
Disassembler::ParseInstructions
(
    const ExecutionContext *exe_ctx,
    const AddressRange &range
)
{
    Target *target = exe_ctx->target;
    const addr_t byte_size = range.GetByteSize();
    if (target == NULL || byte_size == 0 || !range.GetBaseAddress().IsValid())
        return 0;

    DataBufferHeap *heap_buffer = new DataBufferHeap (byte_size, '\0');
    DataBufferSP data_sp(heap_buffer);

    Error error;
    const bool prefer_file_cache = true;
    const size_t bytes_read = target->ReadMemory (range.GetBaseAddress(),
                                                  prefer_file_cache,
                                                  heap_buffer->GetBytes(),
                                                  heap_buffer->GetByteSize(),
                                                  error);

    if (bytes_read > 0)
    {
        if (bytes_read != heap_buffer->GetByteSize())
            heap_buffer->SetByteSize (bytes_read);
        DataExtractor data (data_sp,
                            m_arch.GetByteOrder(),
                            m_arch.GetAddressByteSize());
        return DecodeInstructions (range.GetBaseAddress(), data, 0, UINT32_MAX, false);
    }

    return 0;
}

size_t
Disassembler::ParseInstructions
(
    const ExecutionContext *exe_ctx,
    const Address &start,
    uint32_t num_instructions
)
{
    m_instruction_list.Clear();

    if (num_instructions == 0 || !start.IsValid())
        return 0;

    Target *target = exe_ctx->target;
    // Calculate the max buffer size we will need in order to disassemble
    const addr_t byte_size = num_instructions * m_arch.GetMaximumOpcodeByteSize();

    if (target == NULL || byte_size == 0)
        return 0;

    DataBufferHeap *heap_buffer = new DataBufferHeap (byte_size, '\0');
    DataBufferSP data_sp (heap_buffer);

    Error error;
    bool prefer_file_cache = true;
    const size_t bytes_read = target->ReadMemory (start,
                                                  prefer_file_cache,
                                                  heap_buffer->GetBytes(),
                                                  byte_size,
                                                  error);

    if (bytes_read == 0)
        return 0;
    DataExtractor data (data_sp,
                        m_arch.GetByteOrder(),
                        m_arch.GetAddressByteSize());

    const bool append_instructions = true;
    DecodeInstructions (start,
                        data,
                        0,
                        num_instructions,
                        append_instructions);

    return m_instruction_list.GetSize();
}

//----------------------------------------------------------------------
// Disassembler copy constructor
//----------------------------------------------------------------------
Disassembler::Disassembler(const ArchSpec& arch) :
    m_arch (arch),
    m_instruction_list(),
    m_base_addr(LLDB_INVALID_ADDRESS)
{

}

//----------------------------------------------------------------------
// Destructor
//----------------------------------------------------------------------
Disassembler::~Disassembler()
{
}

InstructionList &
Disassembler::GetInstructionList ()
{
    return m_instruction_list;
}

const InstructionList &
Disassembler::GetInstructionList () const
{
    return m_instruction_list;
}

//----------------------------------------------------------------------
// Class PseudoInstruction
//----------------------------------------------------------------------
PseudoInstruction::PseudoInstruction () :
    Instruction (Address(), eAddressClassUnknown),
    m_description ()
{
}

PseudoInstruction::~PseudoInstruction ()
{
}

void
PseudoInstruction::Dump (lldb_private::Stream *s,
                        uint32_t max_opcode_byte_size,
                        bool show_address,
                        bool show_bytes,
                        const lldb_private::ExecutionContext* exe_ctx,
                        bool raw)
{
    if (!s)
        return;

    if (show_bytes)
        m_opcode.Dump (s, max_opcode_byte_size);

    if (m_description.size() > 0)
        s->Printf ("%s", m_description.c_str());
    else
        s->Printf ("<unknown>");

}

bool
PseudoInstruction::DoesBranch () const
{
    // This is NOT a valid question for a pseudo instruction.
    return false;
}

size_t
PseudoInstruction::Decode (const lldb_private::Disassembler &disassembler,
                           const lldb_private::DataExtractor &data,
                           uint32_t data_offset)
{
    return m_opcode.GetByteSize();
}


void
PseudoInstruction::SetOpcode (size_t opcode_size, void *opcode_data)
{
    if (!opcode_data)
        return;

    switch (opcode_size)
    {
        case 8:
        {
            uint8_t value8 = *((uint8_t *) opcode_data);
            m_opcode.SetOpcode8 (value8);
            break;
         }
        case 16:
        {
            uint16_t value16 = *((uint16_t *) opcode_data);
            m_opcode.SetOpcode16 (value16);
            break;
         }
        case 32:
        {
            uint32_t value32 = *((uint32_t *) opcode_data);
            m_opcode.SetOpcode32 (value32);
            break;
         }
        case 64:
        {
            uint64_t value64 = *((uint64_t *) opcode_data);
            m_opcode.SetOpcode64 (value64);
            break;
         }
        default:
            break;
    }
}

void
PseudoInstruction::SetDescription (const char *description)
{
    if (description && strlen (description) > 0)
        m_description = description;
}