path: root/source/Plugins/ABI/SysV-mips/ABISysV_mips.cpp

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

#include "ABISysV_mips.h"

// C Includes
// C++ Includes
// Other libraries and framework includes
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Triple.h"

// Project includes
#include "lldb/Core/ConstString.h"
#include "lldb/Core/DataExtractor.h"
#include "lldb/Core/Error.h"
#include "lldb/Core/Log.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/RegisterValue.h"
#include "lldb/Core/Value.h"
#include "lldb/Core/ValueObjectConstResult.h"
#include "lldb/Core/ValueObjectRegister.h"
#include "lldb/Core/ValueObjectMemory.h"
#include "lldb/Symbol/UnwindPlan.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/StackFrame.h"
#include "lldb/Target/Thread.h"

using namespace lldb;
using namespace lldb_private;

enum dwarf_regnums
{
    dwarf_r0 = 0,
    dwarf_r1,
    dwarf_r2,
    dwarf_r3,
    dwarf_r4,
    dwarf_r5,
    dwarf_r6,
    dwarf_r7,
    dwarf_r8,
    dwarf_r9,
    dwarf_r10,
    dwarf_r11,
    dwarf_r12,
    dwarf_r13,
    dwarf_r14,
    dwarf_r15,
    dwarf_r16,
    dwarf_r17,
    dwarf_r18,
    dwarf_r19,
    dwarf_r20,
    dwarf_r21,
    dwarf_r22,
    dwarf_r23,
    dwarf_r24,
    dwarf_r25,
    dwarf_r26,
    dwarf_r27,
    dwarf_r28,
    dwarf_r29,
    dwarf_r30,
    dwarf_r31,
    dwarf_sr,
    dwarf_lo,
    dwarf_hi,
    dwarf_bad,
    dwarf_cause,
    dwarf_pc
};

static const RegisterInfo
g_register_infos[] =
{
   //  NAME      ALT    SZ OFF ENCODING        FORMAT         EH_FRAME           DWARF                   GENERIC                     PROCESS PLUGINS         LLDB NATIVE            VALUE REGS  INVALIDATE REGS
  //  ========  ======  == === =============  ===========    ============       ==============          ============                =================       ===================     ========== =================
    { "r0"    , "zero", 4,  0, eEncodingUint, eFormatHex,  {     dwarf_r0,          dwarf_r0,           LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r1"    , "AT",   4,  0, eEncodingUint, eFormatHex,  {     dwarf_r1,          dwarf_r1,           LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r2"    , "v0",   4,  0, eEncodingUint, eFormatHex,  {     dwarf_r2,          dwarf_r2,           LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r3"    , "v1",   4,  0, eEncodingUint, eFormatHex,  {     dwarf_r3,          dwarf_r3,           LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r4"    , "arg1", 4,  0, eEncodingUint, eFormatHex,  {     dwarf_r4,          dwarf_r4,           LLDB_REGNUM_GENERIC_ARG1,   LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r5"    , "arg2", 4,  0, eEncodingUint, eFormatHex,  {     dwarf_r5,          dwarf_r5,           LLDB_REGNUM_GENERIC_ARG2,   LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r6"    , "arg3", 4,  0, eEncodingUint, eFormatHex,  {     dwarf_r6,          dwarf_r6,           LLDB_REGNUM_GENERIC_ARG3,   LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r7"    , "arg4", 4,  0, eEncodingUint, eFormatHex,  {     dwarf_r7,          dwarf_r7,           LLDB_REGNUM_GENERIC_ARG4,   LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r8"    , "arg5", 4,  0, eEncodingUint, eFormatHex,  {     dwarf_r8,          dwarf_r8,           LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r9"    , "arg6", 4,  0, eEncodingUint, eFormatHex,  {     dwarf_r9,          dwarf_r9,           LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r10"   , "arg7", 4,  0, eEncodingUint, eFormatHex,  {     dwarf_r10,         dwarf_r10,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r11"   , "arg8", 4,  0, eEncodingUint, eFormatHex,  {     dwarf_r11,         dwarf_r11,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r12"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r12,         dwarf_r12,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r13"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r13,         dwarf_r13,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r14"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r14,         dwarf_r14,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r15"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r15,         dwarf_r15,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r16"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r16,         dwarf_r16,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r17"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r17,         dwarf_r17,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r18"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r18,         dwarf_r18,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r19"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r19,         dwarf_r19,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r20"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r20,         dwarf_r20,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r21"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r21,         dwarf_r21,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r22"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r22,         dwarf_r22,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r23"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r23,         dwarf_r23,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r24"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r24,         dwarf_r24,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r25"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r25,         dwarf_r25,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r26"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r26,         dwarf_r26,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r27"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_r27,         dwarf_r27,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r28"   , "gp",   4,  0, eEncodingUint, eFormatHex,  {     dwarf_r28,         dwarf_r28,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r29"   , "sp",   4,  0, eEncodingUint, eFormatHex,  {     dwarf_r29,         dwarf_r29,          LLDB_REGNUM_GENERIC_SP,     LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r30"   , "fp",   4,  0, eEncodingUint, eFormatHex,  {     dwarf_r30,         dwarf_r30,          LLDB_REGNUM_GENERIC_FP,     LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "r31"   , "ra",   4,  0, eEncodingUint, eFormatHex,  {     dwarf_r31,         dwarf_r31,          LLDB_REGNUM_GENERIC_RA,     LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "sr"    , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_sr,          dwarf_sr,           LLDB_REGNUM_GENERIC_FLAGS,  LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "lo"    , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_lo,          dwarf_lo,           LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "hi"    , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_hi,          dwarf_hi,           LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "bad"   , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_bad,         dwarf_bad,          LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "cause" , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_cause,       dwarf_cause,        LLDB_INVALID_REGNUM,        LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
    { "pc"    , nullptr,4,  0, eEncodingUint, eFormatHex,  {     dwarf_pc,          dwarf_pc,           LLDB_REGNUM_GENERIC_PC,     LLDB_INVALID_REGNUM,    LLDB_INVALID_REGNUM },  nullptr,   nullptr },
};

static const uint32_t k_num_register_infos = llvm::array_lengthof(g_register_infos);

const lldb_private::RegisterInfo *
ABISysV_mips::GetRegisterInfoArray (uint32_t &count)
{
    count = k_num_register_infos;
    return g_register_infos;
}

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

//------------------------------------------------------------------
// Static Functions
//------------------------------------------------------------------

ABISP
ABISysV_mips::CreateInstance (const ArchSpec &arch)
{
    static ABISP g_abi_sp;
    const llvm::Triple::ArchType arch_type = arch.GetTriple().getArch();
    if ((arch_type == llvm::Triple::mips) ||
        (arch_type == llvm::Triple::mipsel))
    {
        if (!g_abi_sp)
            g_abi_sp.reset (new ABISysV_mips);
        return g_abi_sp;
    }
    return ABISP();
}

bool
ABISysV_mips::PrepareTrivialCall (Thread &thread,
                                  addr_t sp,
                                  addr_t func_addr,
                                  addr_t return_addr,
                                  llvm::ArrayRef<addr_t> args) const
{
    Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));

    if (log)
    {
        StreamString s;
        s.Printf("ABISysV_mips::PrepareTrivialCall (tid = 0x%" PRIx64 ", sp = 0x%" PRIx64 ", func_addr = 0x%" PRIx64 ", return_addr = 0x%" PRIx64,
                    thread.GetID(),
                    (uint64_t)sp,
                    (uint64_t)func_addr,
                    (uint64_t)return_addr);

        for (size_t i = 0; i < args.size(); ++i)
            s.Printf (", arg%zd = 0x%" PRIx64, i + 1, args[i]);
        s.PutCString (")");
        log->PutCString(s.GetString().c_str());
    }

    RegisterContext *reg_ctx = thread.GetRegisterContext().get();
    if (!reg_ctx)
        return false;

    const RegisterInfo *reg_info = nullptr;

    RegisterValue reg_value;

    // Argument registers
    const char *reg_names[] = { "r4", "r5", "r6", "r7" };

    llvm::ArrayRef<addr_t>::iterator ai = args.begin(), ae = args.end();

    // Write arguments to registers
    for (size_t i = 0; i < llvm::array_lengthof(reg_names); ++i)
    {
        if (ai == ae)
            break;

        reg_info = reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG1 + i);
        if (log)
            log->Printf("About to write arg%zd (0x%" PRIx64 ") into %s", i + 1, args[i], reg_info->name);

        if (!reg_ctx->WriteRegisterFromUnsigned(reg_info, args[i]))
            return false;

        ++ai;
    }

    // If we have more than 4 arguments --Spill onto the stack
    if (ai != ae)
    {
        // No of arguments to go on stack 
        size_t num_stack_regs = args.size();

        // Allocate needed space for args on the stack
        sp -= (num_stack_regs * 4);

        // Keep the stack 8 byte aligned
        sp &= ~(8ull-1ull);

        // just using arg1 to get the right size
        const RegisterInfo *reg_info = reg_ctx->GetRegisterInfo(eRegisterKindGeneric, LLDB_REGNUM_GENERIC_ARG1);
        
        addr_t arg_pos = sp+16;
        
        size_t i = 4;
        for (; ai != ae; ++ai)
        {
            reg_value.SetUInt32(*ai);
            if (log)
                log->Printf("About to write arg%zd (0x%" PRIx64 ") at  0x%" PRIx64 "", i+1, args[i], arg_pos);
            
            if (reg_ctx->WriteRegisterValueToMemory(reg_info, arg_pos, reg_info->byte_size, reg_value).Fail())
                return false;
            arg_pos += reg_info->byte_size;
            i++;
        }
    }

    Error error;
    const RegisterInfo *pc_reg_info = reg_ctx->GetRegisterInfo (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
    const RegisterInfo *sp_reg_info = reg_ctx->GetRegisterInfo (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_SP);
    const RegisterInfo *ra_reg_info = reg_ctx->GetRegisterInfo (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_RA);
    const RegisterInfo *r25_info = reg_ctx->GetRegisterInfoByName("r25", 0);
    const RegisterInfo *r0_info = reg_ctx->GetRegisterInfoByName("zero", 0);

    if (log)
        log->Printf("Writing R0: 0x%" PRIx64, (uint64_t)0);

    /* Write r0 with 0, in case we are stopped in syscall,
     * such setting prevents automatic decrement of the PC.
     * This clears the bug 23659 for MIPS.
    */ 
    if (!reg_ctx->WriteRegisterFromUnsigned (r0_info, (uint64_t)0))
        return false;

    if (log)
        log->Printf("Writing SP: 0x%" PRIx64, (uint64_t)sp);

    // Set "sp" to the requested value
    if (!reg_ctx->WriteRegisterFromUnsigned (sp_reg_info, sp))
        return false;

    if (log)
        log->Printf("Writing RA: 0x%" PRIx64, (uint64_t)return_addr);

    // Set "ra" to the return address
    if (!reg_ctx->WriteRegisterFromUnsigned (ra_reg_info, return_addr))
        return false;

    if (log)
        log->Printf("Writing PC: 0x%" PRIx64, (uint64_t)func_addr);

    // Set pc to the address of the called function.
    if (!reg_ctx->WriteRegisterFromUnsigned (pc_reg_info, func_addr))
        return false;
    
    if (log)
        log->Printf("Writing r25: 0x%" PRIx64, (uint64_t)func_addr);
    
    // All callers of position independent functions must place the address of the called function in t9 (r25)
    if (!reg_ctx->WriteRegisterFromUnsigned (r25_info, func_addr))
        return false;
  
    return true;
}

bool
ABISysV_mips::GetArgumentValues (Thread &thread, ValueList &values) const
{
    return false;
}

Error
ABISysV_mips::SetReturnValueObject(lldb::StackFrameSP &frame_sp, lldb::ValueObjectSP &new_value_sp)
{
    Error 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;
        Error 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 *r2_info = reg_ctx->GetRegisterInfoByName("r2", 0);
            if (num_bytes <= 4)
            {
                uint32_t raw_value = data.GetMaxU32(&offset, num_bytes);

                if (reg_ctx->WriteRegisterFromUnsigned (r2_info, raw_value))
                    set_it_simple = true;
            }
            else
            {
                uint32_t raw_value = data.GetMaxU32(&offset, 4);

                if (reg_ctx->WriteRegisterFromUnsigned (r2_info, raw_value))
                {
                    const RegisterInfo *r3_info = reg_ctx->GetRegisterInfoByName("r3", 0);
                    uint32_t raw_value = data.GetMaxU32(&offset, num_bytes - offset);

                    if (reg_ctx->WriteRegisterFromUnsigned (r3_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
ABISysV_mips::GetReturnValueObjectSimple (Thread &thread, CompilerType &return_compiler_type) const
{
    ValueObjectSP return_valobj_sp;
    return return_valobj_sp;
}

ValueObjectSP
ABISysV_mips::GetReturnValueObjectImpl (Thread &thread, CompilerType &return_compiler_type) const
{
    ValueObjectSP return_valobj_sp;
    Value value;

    if (!return_compiler_type)
        return return_valobj_sp;

    ExecutionContext exe_ctx (thread.shared_from_this());
    if (exe_ctx.GetTargetPtr() == nullptr || exe_ctx.GetProcessPtr() == nullptr)
        return return_valobj_sp;

    Target *target = exe_ctx.GetTargetPtr();
    const ArchSpec target_arch = target->GetArchitecture();
    ByteOrder target_byte_order = target_arch.GetByteOrder();
    value.SetCompilerType(return_compiler_type);
    uint32_t fp_flag = target_arch.GetFlags() & lldb_private::ArchSpec::eMIPS_ABI_FP_mask;

    RegisterContext *reg_ctx = thread.GetRegisterContext().get();
    if (!reg_ctx)
        return return_valobj_sp;
    
    bool is_signed = false;
    bool is_complex = false;
    uint32_t count = 0;

    // In MIPS register "r2" (v0) holds the integer function return values
    const RegisterInfo *r2_reg_info = reg_ctx->GetRegisterInfoByName("r2", 0);
    size_t bit_width = return_compiler_type.GetBitSize(&thread); 
    if (return_compiler_type.IsIntegerOrEnumerationType (is_signed))
    {
        switch (bit_width)
        {
            default:
                return return_valobj_sp;
            case 64:
            {
                const RegisterInfo *r3_reg_info = reg_ctx->GetRegisterInfoByName("r3", 0);
                uint64_t raw_value;
                raw_value = reg_ctx->ReadRegisterAsUnsigned(r2_reg_info, 0) & UINT32_MAX;
                raw_value |= ((uint64_t)(reg_ctx->ReadRegisterAsUnsigned(r3_reg_info, 0) & UINT32_MAX)) << 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)(reg_ctx->ReadRegisterAsUnsigned(r2_reg_info, 0) & UINT32_MAX);
                else
                    value.GetScalar() = (uint32_t)(reg_ctx->ReadRegisterAsUnsigned(r2_reg_info, 0) & UINT32_MAX);
                break;
            case 16:
                if (is_signed)
                    value.GetScalar() = (int16_t)(reg_ctx->ReadRegisterAsUnsigned(r2_reg_info, 0) & UINT16_MAX);
                else
                    value.GetScalar() = (uint16_t)(reg_ctx->ReadRegisterAsUnsigned(r2_reg_info, 0) & UINT16_MAX);
                break;
            case 8:
                if (is_signed)
                    value.GetScalar() = (int8_t)(reg_ctx->ReadRegisterAsUnsigned(r2_reg_info, 0) & UINT8_MAX);
                else
                    value.GetScalar() = (uint8_t)(reg_ctx->ReadRegisterAsUnsigned(r2_reg_info, 0) & UINT8_MAX);
                break;
        }
    }
    else if (return_compiler_type.IsPointerType ())
    {
        uint32_t ptr = thread.GetRegisterContext()->ReadRegisterAsUnsigned(r2_reg_info, 0) & UINT32_MAX;
        value.GetScalar() = ptr;
    }
    else if (return_compiler_type.IsAggregateType ())
    {
        // Structure/Vector is always passed in memory and pointer to that memory is passed in r2. 
        uint64_t mem_address = reg_ctx->ReadRegisterAsUnsigned(reg_ctx->GetRegisterInfoByName("r2", 0), 0);
        // We have got the address. Create a memory object out of it
        return_valobj_sp = ValueObjectMemory::Create(&thread,
                                                     "",
                                                     Address(mem_address, nullptr),
                                                     return_compiler_type);
        return return_valobj_sp;
    }
    else if (return_compiler_type.IsFloatingPointType (count, is_complex))
    {
        if (IsSoftFloat (fp_flag))
        {
            uint64_t raw_value = reg_ctx->ReadRegisterAsUnsigned(r2_reg_info, 0);
            if (count != 1 && is_complex)
                return return_valobj_sp;
            switch (bit_width)
            {
                default:
                    return return_valobj_sp;
                case 32:
                    static_assert(sizeof(float) == sizeof(uint32_t), "");
                    value.GetScalar() = *((float *)(&raw_value));
                    break;
                case 64:
                    static_assert(sizeof(double) == sizeof(uint64_t), "");
                    const RegisterInfo *r3_reg_info = reg_ctx->GetRegisterInfoByName("r3", 0);
                    if (target_byte_order == eByteOrderLittle)
                        raw_value = ((reg_ctx->ReadRegisterAsUnsigned(r3_reg_info, 0)) << 32) | raw_value;
                    else
                        raw_value = (raw_value << 32) | reg_ctx->ReadRegisterAsUnsigned(r3_reg_info, 0);
                    value.GetScalar() = *((double *)(&raw_value));
                    break;
            }
        }
    
        else
        {
            const RegisterInfo *f0_info = reg_ctx->GetRegisterInfoByName("f0", 0);
            RegisterValue f0_value;
            DataExtractor f0_data;
            reg_ctx->ReadRegister (f0_info, f0_value);
            f0_value.GetData(f0_data);
            lldb::offset_t offset = 0;

            if (count == 1 && !is_complex)
            {
                switch (bit_width)
                {
                    default:
                        return return_valobj_sp;
                    case 64:
                    {
                        static_assert(sizeof(double) == sizeof(uint64_t), "");
                        const RegisterInfo *f1_info = reg_ctx->GetRegisterInfoByName("f1", 0);
                        RegisterValue f1_value;
                        DataExtractor f1_data;
                        reg_ctx->ReadRegister (f1_info, f1_value);
                        DataExtractor *copy_from_extractor = nullptr;
                        DataBufferSP data_sp (new DataBufferHeap(8, 0));
                        DataExtractor return_ext (data_sp,
                                                  target_byte_order,
                                                  target->GetArchitecture().GetAddressByteSize());

                        if (target_byte_order == eByteOrderLittle)
                        {
                            copy_from_extractor = &f0_data;
                            copy_from_extractor->CopyByteOrderedData (offset,
                                                                      4,
                                                                      data_sp->GetBytes(),
                                                                      4,
                                                                      target_byte_order);
                            f1_value.GetData(f1_data);
                            copy_from_extractor = &f1_data;
                            copy_from_extractor->CopyByteOrderedData (offset,
                                                                      4,
                                                                      data_sp->GetBytes() + 4,
                                                                      4,
                                                                      target_byte_order);
                        }
                        else
                        {
                            copy_from_extractor = &f0_data;
                            copy_from_extractor->CopyByteOrderedData (offset,
                                                                      4,
                                                                      data_sp->GetBytes() + 4,
                                                                      4,
                                                                      target_byte_order);
                            f1_value.GetData(f1_data);
                            copy_from_extractor = &f1_data;
                            copy_from_extractor->CopyByteOrderedData (offset,
                                                                      4,
                                                                      data_sp->GetBytes(),
                                                                      4,
                                                                      target_byte_order);
                        }
                        value.GetScalar() = (double) return_ext.GetDouble(&offset);
                        break;
                    }
                    case 32:
                    {
                        static_assert(sizeof(float) == sizeof(uint32_t), "");
                        value.GetScalar() = (float) f0_data.GetFloat(&offset);
                        break;
                    }
                }
            }
            else
            {
                // not handled yet
                return return_valobj_sp;
            }
        }
    }
    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;
}

bool
ABISysV_mips::CreateFunctionEntryUnwindPlan (UnwindPlan &unwind_plan)
{
    unwind_plan.Clear();
    unwind_plan.SetRegisterKind (eRegisterKindDWARF);

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

    // Our Call Frame Address is the stack pointer value
    row->GetCFAValue().SetIsRegisterPlusOffset(dwarf_r29, 0);

    // The previous PC is in the RA
    row->SetRegisterLocationToRegister(dwarf_pc, dwarf_r31, true);
    unwind_plan.AppendRow (row);

    // All other registers are the same.

    unwind_plan.SetSourceName ("mips at-func-entry default");
    unwind_plan.SetSourcedFromCompiler (eLazyBoolNo);
    unwind_plan.SetReturnAddressRegister(dwarf_r31);
    return true;
}

bool
ABISysV_mips::CreateDefaultUnwindPlan (UnwindPlan &unwind_plan)
{
    unwind_plan.Clear();
    unwind_plan.SetRegisterKind (eRegisterKindDWARF);

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

    row->GetCFAValue().SetIsRegisterPlusOffset(dwarf_r29, 0);

    row->SetRegisterLocationToRegister(dwarf_pc, dwarf_r31, true);
	
    unwind_plan.AppendRow (row);
    unwind_plan.SetSourceName ("mips default unwind plan");
    unwind_plan.SetSourcedFromCompiler (eLazyBoolNo);
    unwind_plan.SetUnwindPlanValidAtAllInstructions (eLazyBoolNo);
    return true;
}

bool
ABISysV_mips::RegisterIsVolatile (const RegisterInfo *reg_info)
{
    return !RegisterIsCalleeSaved (reg_info);
}

bool
ABISysV_mips::IsSoftFloat(uint32_t fp_flags) const
{
    return (fp_flags == lldb_private::ArchSpec::eMIPS_ABI_FP_SOFT);
}

bool
ABISysV_mips::RegisterIsCalleeSaved (const RegisterInfo *reg_info)
{
    if (reg_info)
    {
        // Preserved registers are :
        // r16-r23, r28, r29, r30, r31
        const char *name = reg_info->name;

        if (name[0] == 'r')
        {
            switch (name[1])
            {
                case '1': 
                    if (name[2] == '6' || name[2] == '7' || name[2] == '8' || name[2] == '9') // r16-r19
                        return name[3] == '\0';
                break;
                case '2': 
                    if (name[2] == '0' || name[2] == '1' || name[2] == '2' || name[2] == '3'  // r20-r23
                        || name[2] == '8' || name[2] == '9')                                  // r28 and r29
                        return name[3] == '\0';
                break;
                case '3': 
                    if (name[2] == '0' || name[2] == '1')       // r30 and r31
                        return name[3] == '\0';
                break;
            }

            if (name[0] == 'g' && name[1] == 'p' && name[2] == '\0')   // gp (r28)
                return true;
            if (name[0] == 's' && name[1] == 'p' && name[2] == '\0')   // sp (r29)
                return true;
            if (name[0] == 'f' && name[1] == 'p' && name[2] == '\0')   // fp (r30)
                return true;
            if (name[0] == 'r' && name[1] == 'a' && name[2] == '\0')   // ra (r31)
                return true;
        }
    }
    return false;
}

void
ABISysV_mips::Initialize()
{
    PluginManager::RegisterPlugin (GetPluginNameStatic(),
                                   "System V ABI for mips targets",
                                   CreateInstance);
}

void
ABISysV_mips::Terminate()
{
    PluginManager::UnregisterPlugin (CreateInstance);
}

lldb_private::ConstString
ABISysV_mips::GetPluginNameStatic()
{
    static ConstString g_name("sysv-mips");
    return g_name;
}

//------------------------------------------------------------------
// PluginInterface protocol
//------------------------------------------------------------------

lldb_private::ConstString
ABISysV_mips::GetPluginName()
{
    return GetPluginNameStatic();
}

uint32_t
ABISysV_mips::GetPluginVersion()
{
    return 1;
}