ABISysV_mips64.cpp

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//===-- ABISysV_mips64.cpp ------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#include "ABISysV_mips64.h"
 
#include "llvm/ADT/STLExtras.h"
#include "llvm/TargetParser/Triple.h"
 
#include "lldb/Core/Module.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/Value.h"
#include "lldb/Core/ValueObjectConstResult.h"
#include "lldb/Core/ValueObjectMemory.h"
#include "lldb/Core/ValueObjectRegister.h"
#include "lldb/Symbol/UnwindPlan.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/StackFrame.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Utility/ConstString.h"
#include "lldb/Utility/DataExtractor.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/RegisterValue.h"
#include "lldb/Utility/Status.h"
#include <optional>
 
using namespace lldb;
using namespace lldb_private;
 
LLDB_PLUGIN_DEFINE(ABISysV_mips64)
 
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_mips64[] = {
    //  NAME      ALT    SZ OFF ENCODING        FORMAT         EH_FRAME
    //  DWARF                   GENERIC                     PROCESS PLUGIN
    //  LLDB NATIVE
    //  ========  ======  == === =============  ==========     =============
    //  =================       ====================        =================
    //  ====================
    {"r0",
     "zero",
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r0, dwarf_r0, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r1",
     "AT",
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r1, dwarf_r1, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
 
    },
    {"r2",
     "v0",
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r2, dwarf_r2, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r3",
     "v1",
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r3, dwarf_r3, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r4",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r4, dwarf_r4, LLDB_REGNUM_GENERIC_ARG1, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r5",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r5, dwarf_r5, LLDB_REGNUM_GENERIC_ARG2, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r6",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r6, dwarf_r6, LLDB_REGNUM_GENERIC_ARG3, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r7",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r7, dwarf_r7, LLDB_REGNUM_GENERIC_ARG4, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r8",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r8, dwarf_r8, LLDB_REGNUM_GENERIC_ARG5, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r9",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r9, dwarf_r9, LLDB_REGNUM_GENERIC_ARG6, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r10",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r10, dwarf_r10, LLDB_REGNUM_GENERIC_ARG7, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r11",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r11, dwarf_r11, LLDB_REGNUM_GENERIC_ARG8, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r12",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r12, dwarf_r12, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r13",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r13, dwarf_r13, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r14",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r14, dwarf_r14, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r15",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r15, dwarf_r15, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r16",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r16, dwarf_r16, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r17",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r17, dwarf_r17, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r18",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r18, dwarf_r18, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r19",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r19, dwarf_r19, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r20",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r20, dwarf_r20, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r21",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r21, dwarf_r21, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r22",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r22, dwarf_r22, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r23",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r23, dwarf_r23, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r24",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r24, dwarf_r24, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r25",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r25, dwarf_r25, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r26",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r26, dwarf_r26, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r27",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r27, dwarf_r27, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r28",
     "gp",
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r28, dwarf_r28, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r29",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r29, dwarf_r29, LLDB_REGNUM_GENERIC_SP, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r30",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r30, dwarf_r30, LLDB_REGNUM_GENERIC_FP, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"r31",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_r31, dwarf_r31, LLDB_REGNUM_GENERIC_RA, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"sr",
     nullptr,
     4,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_sr, dwarf_sr, LLDB_REGNUM_GENERIC_FLAGS, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"lo",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_lo, dwarf_lo, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"hi",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_hi, dwarf_hi, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"bad",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_bad, dwarf_bad, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"cause",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_cause, dwarf_cause, LLDB_INVALID_REGNUM, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
    {"pc",
     nullptr,
     8,
     0,
     eEncodingUint,
     eFormatHex,
     {dwarf_pc, dwarf_pc, LLDB_REGNUM_GENERIC_PC, LLDB_INVALID_REGNUM,
      LLDB_INVALID_REGNUM},
     nullptr,
     nullptr,
     nullptr,
    },
};
 
static const uint32_t k_num_register_infos = std::size(g_register_infos_mips64);
 
const lldb_private::RegisterInfo *
ABISysV_mips64::GetRegisterInfoArray(uint32_t &count) {
  count = k_num_register_infos;
  return g_register_infos_mips64;
}
 
size_t ABISysV_mips64::GetRedZoneSize() const { return 0; }
 
// Static Functions
 
ABISP
ABISysV_mips64::CreateInstance(lldb::ProcessSP process_sp, const ArchSpec &arch) {
  if (arch.GetTriple().isMIPS64())
    return ABISP(
        new ABISysV_mips64(std::move(process_sp), MakeMCRegisterInfo(arch)));
  return ABISP();
}
 
bool ABISysV_mips64::PrepareTrivialCall(Thread &thread, addr_t sp,
                                        addr_t func_addr, addr_t return_addr,
                                        llvm::ArrayRef<addr_t> args) const {
  Log *log = GetLog(LLDBLog::Expressions);
 
  if (log) {
    StreamString s;
    s.Printf("ABISysV_mips64::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->PutString(s.GetString());
  }
 
  RegisterContext *reg_ctx = thread.GetRegisterContext().get();
  if (!reg_ctx)
    return false;
 
  const RegisterInfo *reg_info = nullptr;
 
  if (args.size() > 8) // TODO handle more than 8 arguments
    return false;
 
  for (size_t i = 0; i < args.size(); ++i) {
    reg_info = reg_ctx->GetRegisterInfo(eRegisterKindGeneric,
                                        LLDB_REGNUM_GENERIC_ARG1 + i);
    LLDB_LOGF(log, "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;
  }
 
  // First, align the SP
 
  LLDB_LOGF(log, "16-byte aligning SP: 0x%" PRIx64 " to 0x%" PRIx64,
            (uint64_t)sp, (uint64_t)(sp & ~0xfull));
 
  sp &= ~(0xfull); // 16-byte alignment
 
  Status 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);
 
  LLDB_LOGF(log, "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;
 
  LLDB_LOGF(log, "Writing SP: 0x%" PRIx64, (uint64_t)sp);
 
  // Set "sp" to the requested value
  if (!reg_ctx->WriteRegisterFromUnsigned(sp_reg_info, sp))
    return false;
 
  LLDB_LOGF(log, "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;
 
  LLDB_LOGF(log, "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;
 
  LLDB_LOGF(log, "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_mips64::GetArgumentValues(Thread &thread,
                                       ValueList &values) const {
  return false;
}
 
Status ABISysV_mips64::SetReturnValueObject(lldb::StackFrameSP &frame_sp,
                                            lldb::ValueObjectSP &new_value_sp) {
  Status error;
  if (!new_value_sp) {
    error.SetErrorString("Empty value object for return value.");
    return error;
  }
 
  CompilerType compiler_type = new_value_sp->GetCompilerType();
  if (!compiler_type) {
    error.SetErrorString("Null clang type for return value.");
    return error;
  }
 
  Thread *thread = frame_sp->GetThread().get();
 
  RegisterContext *reg_ctx = thread->GetRegisterContext().get();
 
  if (!reg_ctx)
    error.SetErrorString("no registers are available");
 
  DataExtractor data;
  Status data_error;
  size_t num_bytes = new_value_sp->GetData(data, data_error);
  if (data_error.Fail()) {
    error.SetErrorStringWithFormat(
        "Couldn't convert return value to raw data: %s",
        data_error.AsCString());
    return error;
  }
 
  const uint32_t type_flags = compiler_type.GetTypeInfo(nullptr);
 
  if (type_flags & eTypeIsScalar || type_flags & eTypeIsPointer) {
    if (type_flags & eTypeIsInteger || type_flags & eTypeIsPointer) {
      lldb::offset_t offset = 0;
 
      if (num_bytes <= 16) {
        const RegisterInfo *r2_info = reg_ctx->GetRegisterInfoByName("r2", 0);
        if (num_bytes <= 8) {
          uint64_t raw_value = data.GetMaxU64(&offset, num_bytes);
 
          if (!reg_ctx->WriteRegisterFromUnsigned(r2_info, raw_value))
            error.SetErrorString("failed to write register r2");
        } else {
          uint64_t raw_value = data.GetMaxU64(&offset, 8);
          if (reg_ctx->WriteRegisterFromUnsigned(r2_info, raw_value)) {
            const RegisterInfo *r3_info =
                reg_ctx->GetRegisterInfoByName("r3", 0);
            raw_value = data.GetMaxU64(&offset, num_bytes - offset);
 
            if (!reg_ctx->WriteRegisterFromUnsigned(r3_info, raw_value))
              error.SetErrorString("failed to write register r3");
          } else
            error.SetErrorString("failed to write register r2");
        }
      } else {
        error.SetErrorString("We don't support returning longer than 128 bit "
                             "integer values at present.");
      }
    } else if (type_flags & eTypeIsFloat) {
      error.SetErrorString("TODO: Handle Float Types.");
    }
  } else if (type_flags & eTypeIsVector) {
    error.SetErrorString("returning vector values are not supported");
  }
 
  return error;
}
 
ValueObjectSP ABISysV_mips64::GetReturnValueObjectSimple(
    Thread &thread, CompilerType &return_compiler_type) const {
  ValueObjectSP return_valobj_sp;
  return return_valobj_sp;
}
 
ValueObjectSP ABISysV_mips64::GetReturnValueObjectImpl(
    Thread &thread, CompilerType &return_compiler_type) const {
  ValueObjectSP return_valobj_sp;
  Value value;
  Status error;
 
  ExecutionContext exe_ctx(thread.shared_from_this());
  if (exe_ctx.GetTargetPtr() == nullptr || exe_ctx.GetProcessPtr() == nullptr)
    return return_valobj_sp;
 
  value.SetCompilerType(return_compiler_type);
 
  RegisterContext *reg_ctx = thread.GetRegisterContext().get();
  if (!reg_ctx)
    return return_valobj_sp;
 
  Target *target = exe_ctx.GetTargetPtr();
  const ArchSpec target_arch = target->GetArchitecture();
  ByteOrder target_byte_order = target_arch.GetByteOrder();
  std::optional<uint64_t> byte_size = return_compiler_type.GetByteSize(&thread);
  if (!byte_size)
    return return_valobj_sp;
  const uint32_t type_flags = return_compiler_type.GetTypeInfo(nullptr);
  uint32_t fp_flag =
      target_arch.GetFlags() & lldb_private::ArchSpec::eMIPS_ABI_FP_mask;
 
  const RegisterInfo *r2_info = reg_ctx->GetRegisterInfoByName("r2", 0);
  const RegisterInfo *r3_info = reg_ctx->GetRegisterInfoByName("r3", 0);
  assert(r2_info && r3_info && "Basic registers should always be present.");
 
  if (type_flags & eTypeIsScalar || type_flags & eTypeIsPointer) {
    value.SetValueType(Value::ValueType::Scalar);
 
    bool success = false;
    if (type_flags & eTypeIsInteger || type_flags & eTypeIsPointer) {
      // Extract the register context so we can read arguments from registers
      // In MIPS register "r2" (v0) holds the integer function return values
 
      uint64_t raw_value = reg_ctx->ReadRegisterAsUnsigned(r2_info, 0);
 
      const bool is_signed = (type_flags & eTypeIsSigned) != 0;
      switch (*byte_size) {
      default:
        break;
 
      case sizeof(uint64_t):
        if (is_signed)
          value.GetScalar() = (int64_t)(raw_value);
        else
          value.GetScalar() = (uint64_t)(raw_value);
        success = true;
        break;
 
      case sizeof(uint32_t):
        if (is_signed)
          value.GetScalar() = (int32_t)(raw_value & UINT32_MAX);
        else
          value.GetScalar() = (uint32_t)(raw_value & UINT32_MAX);
        success = true;
        break;
 
      case sizeof(uint16_t):
        if (is_signed)
          value.GetScalar() = (int16_t)(raw_value & UINT16_MAX);
        else
          value.GetScalar() = (uint16_t)(raw_value & UINT16_MAX);
        success = true;
        break;
 
      case sizeof(uint8_t):
        if (is_signed)
          value.GetScalar() = (int8_t)(raw_value & UINT8_MAX);
        else
          value.GetScalar() = (uint8_t)(raw_value & UINT8_MAX);
        success = true;
        break;
      }
    } else if (type_flags & eTypeIsFloat) {
      if (type_flags & eTypeIsComplex) {
        // Don't handle complex yet.
      } else if (IsSoftFloat(fp_flag)) {
        uint64_t raw_value = reg_ctx->ReadRegisterAsUnsigned(r2_info, 0);
        switch (*byte_size) {
        case 4:
          value.GetScalar() = *((float *)(&raw_value));
          success = true;
          break;
        case 8:
          value.GetScalar() = *((double *)(&raw_value));
          success = true;
          break;
        case 16:
          uint64_t result[2];
          if (target_byte_order == eByteOrderLittle) {
            result[0] = raw_value;
            result[1] = reg_ctx->ReadRegisterAsUnsigned(r3_info, 0);
            value.GetScalar() = *((long double *)(result));
          } else {
            result[0] = reg_ctx->ReadRegisterAsUnsigned(r3_info, 0);
            result[1] = raw_value;
            value.GetScalar() = *((long double *)(result));
          }
          success = true;
          break;
        }
 
      } else {
        if (*byte_size <= sizeof(long double)) {
          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 (*byte_size == sizeof(float)) {
            value.GetScalar() = (float)f0_data.GetFloat(&offset);
            success = true;
          } else if (*byte_size == sizeof(double)) {
            value.GetScalar() = (double)f0_data.GetDouble(&offset);
            success = true;
          } else if (*byte_size == sizeof(long double)) {
            const RegisterInfo *f2_info =
                reg_ctx->GetRegisterInfoByName("f2", 0);
            RegisterValue f2_value;
            DataExtractor f2_data;
            reg_ctx->ReadRegister(f2_info, f2_value);
            DataExtractor *copy_from_extractor = nullptr;
            WritableDataBufferSP data_sp(new DataBufferHeap(16, 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(
                  0, 8, data_sp->GetBytes(), *byte_size - 8, target_byte_order);
              f2_value.GetData(f2_data);
              copy_from_extractor = &f2_data;
              copy_from_extractor->CopyByteOrderedData(
                  0, 8, data_sp->GetBytes() + 8, *byte_size - 8,
                  target_byte_order);
            } else {
              copy_from_extractor = &f0_data;
              copy_from_extractor->CopyByteOrderedData(
                  0, 8, data_sp->GetBytes() + 8, *byte_size - 8,
                  target_byte_order);
              f2_value.GetData(f2_data);
              copy_from_extractor = &f2_data;
              copy_from_extractor->CopyByteOrderedData(
                  0, 8, data_sp->GetBytes(), *byte_size - 8, target_byte_order);
            }
 
            return_valobj_sp = ValueObjectConstResult::Create(
                &thread, return_compiler_type, ConstString(""), return_ext);
            return return_valobj_sp;
          }
        }
      }
    }
 
    if (success)
      return_valobj_sp = ValueObjectConstResult::Create(
          thread.GetStackFrameAtIndex(0).get(), value, ConstString(""));
  } else if (type_flags & eTypeIsStructUnion || type_flags & eTypeIsClass ||
             type_flags & eTypeIsVector) {
    // Any structure of up to 16 bytes in size is returned in the registers.
    if (*byte_size <= 16) {
      WritableDataBufferSP data_sp(new DataBufferHeap(16, 0));
      DataExtractor return_ext(data_sp, target_byte_order,
                               target->GetArchitecture().GetAddressByteSize());
 
      RegisterValue r2_value, r3_value, f0_value, f1_value, f2_value;
      // Tracks how much bytes of r2 and r3 registers we've consumed so far
      uint32_t integer_bytes = 0;
 
      // True if return values are in FP return registers.
      bool use_fp_regs = false;
      // True if we found any non floating point field in structure.
      bool found_non_fp_field = false;
      // True if return values are in r2 register.
      bool use_r2 = false;
      // True if return values are in r3 register.
      bool use_r3 = false;
      // True if the result is copied into our data buffer
      bool sucess = false;
      std::string name;
      bool is_complex;
      uint32_t count;
      const uint32_t num_children = return_compiler_type.GetNumFields();
 
      // A structure consisting of one or two FP values (and nothing else) will
      // be returned in the two FP return-value registers i.e fp0 and fp2.
      if (num_children <= 2) {
        uint64_t field_bit_offset = 0;
 
        // Check if this structure contains only floating point fields
        for (uint32_t idx = 0; idx < num_children; idx++) {
          CompilerType field_compiler_type =
              return_compiler_type.GetFieldAtIndex(idx, name, &field_bit_offset,
                                                   nullptr, nullptr);
 
          if (field_compiler_type.IsFloatingPointType(count, is_complex))
            use_fp_regs = true;
          else
            found_non_fp_field = true;
        }
 
        if (use_fp_regs && !found_non_fp_field) {
          // We have one or two FP-only values in this structure. Get it from
          // f0/f2 registers.
          DataExtractor f0_data, f1_data, f2_data;
          const RegisterInfo *f0_info = reg_ctx->GetRegisterInfoByName("f0", 0);
          const RegisterInfo *f1_info = reg_ctx->GetRegisterInfoByName("f1", 0);
          const RegisterInfo *f2_info = reg_ctx->GetRegisterInfoByName("f2", 0);
 
          reg_ctx->ReadRegister(f0_info, f0_value);
          reg_ctx->ReadRegister(f2_info, f2_value);
 
          f0_value.GetData(f0_data);
 
          for (uint32_t idx = 0; idx < num_children; idx++) {
            CompilerType field_compiler_type =
                return_compiler_type.GetFieldAtIndex(
                    idx, name, &field_bit_offset, nullptr, nullptr);
            std::optional<uint64_t> field_byte_width =
                field_compiler_type.GetByteSize(&thread);
            if (!field_byte_width)
              return return_valobj_sp;
 
            DataExtractor *copy_from_extractor = nullptr;
            uint64_t return_value[2];
            offset_t offset = 0;
 
            if (idx == 0) {
              // This case is for long double type.
              if (*field_byte_width == 16) {
 
                // If structure contains long double type, then it is returned
                // in fp0/fp1 registers.
                if (target_byte_order == eByteOrderLittle) {
                  return_value[0] = f0_data.GetU64(&offset);
                  reg_ctx->ReadRegister(f1_info, f1_value);
                  f1_value.GetData(f1_data);
                  offset = 0;
                  return_value[1] = f1_data.GetU64(&offset);
                } else {
                  return_value[1] = f0_data.GetU64(&offset);
                  reg_ctx->ReadRegister(f1_info, f1_value);
                  f1_value.GetData(f1_data);
                  offset = 0;
                  return_value[0] = f1_data.GetU64(&offset);
                }
 
                f0_data.SetData(return_value, *field_byte_width,
                                target_byte_order);
              }
              copy_from_extractor = &f0_data; // This is in f0, copy from
                                              // register to our result
                                              // structure
            } else {
              f2_value.GetData(f2_data);
              // This is in f2, copy from register to our result structure
              copy_from_extractor = &f2_data;
            }
 
            // Sanity check to avoid crash
            if (!copy_from_extractor ||
                *field_byte_width > copy_from_extractor->GetByteSize())
              return return_valobj_sp;
 
            // copy the register contents into our data buffer
            copy_from_extractor->CopyByteOrderedData(
                0, *field_byte_width,
                data_sp->GetBytes() + (field_bit_offset / 8), *field_byte_width,
                target_byte_order);
          }
 
          // The result is in our data buffer.  Create a variable object out of
          // it
          return_valobj_sp = ValueObjectConstResult::Create(
              &thread, return_compiler_type, ConstString(""), return_ext);
 
          return return_valobj_sp;
        }
      }
 
      // If we reach here, it means this structure either contains more than
      // two fields or it contains at least one non floating point type. In
      // that case, all fields are returned in GP return registers.
      for (uint32_t idx = 0; idx < num_children; idx++) {
        uint64_t field_bit_offset = 0;
        bool is_signed;
        uint32_t padding;
 
        CompilerType field_compiler_type = return_compiler_type.GetFieldAtIndex(
            idx, name, &field_bit_offset, nullptr, nullptr);
        std::optional<uint64_t> field_byte_width =
            field_compiler_type.GetByteSize(&thread);
 
        // if we don't know the size of the field (e.g. invalid type), just
        // bail out
        if (!field_byte_width || *field_byte_width == 0)
          break;
 
        uint32_t field_byte_offset = field_bit_offset / 8;
 
        if (field_compiler_type.IsIntegerOrEnumerationType(is_signed) ||
            field_compiler_type.IsPointerType() ||
            field_compiler_type.IsFloatingPointType(count, is_complex)) {
          padding = field_byte_offset - integer_bytes;
 
          if (integer_bytes < 8) {
            // We have not yet consumed r2 completely.
            if (integer_bytes + *field_byte_width + padding <= 8) {
              // This field fits in r2, copy its value from r2 to our result
              // structure
              integer_bytes = integer_bytes + *field_byte_width +
                              padding; // Increase the consumed bytes.
              use_r2 = true;
            } else {
              // There isn't enough space left in r2 for this field, so this
              // will be in r3.
              integer_bytes = integer_bytes + *field_byte_width +
                              padding; // Increase the consumed bytes.
              use_r3 = true;
            }
          }
          // We already have consumed at-least 8 bytes that means r2 is done,
          // and this field will be in r3. Check if this field can fit in r3.
          else if (integer_bytes + *field_byte_width + padding <= 16) {
            integer_bytes = integer_bytes + *field_byte_width + padding;
            use_r3 = true;
          } else {
            // There isn't any space left for this field, this should not
            // happen as we have already checked the overall size is not
            // greater than 16 bytes. For now, return a nullptr return value
            // object.
            return return_valobj_sp;
          }
        }
      }
      // Vector types up to 16 bytes are returned in GP return registers
      if (type_flags & eTypeIsVector) {
        if (*byte_size <= 8)
          use_r2 = true;
        else {
          use_r2 = true;
          use_r3 = true;
        }
      }
 
      if (use_r2) {
        reg_ctx->ReadRegister(r2_info, r2_value);
 
        const size_t bytes_copied = r2_value.GetAsMemoryData(
            *r2_info, data_sp->GetBytes(), r2_info->byte_size,
            target_byte_order, error);
        if (bytes_copied != r2_info->byte_size)
          return return_valobj_sp;
        sucess = true;
      }
      if (use_r3) {
        reg_ctx->ReadRegister(r3_info, r3_value);
        const size_t bytes_copied = r3_value.GetAsMemoryData(
            *r3_info, data_sp->GetBytes() + r2_info->byte_size,
            r3_info->byte_size, target_byte_order, error);
 
        if (bytes_copied != r3_info->byte_size)
          return return_valobj_sp;
        sucess = true;
      }
      if (sucess) {
        // The result is in our data buffer.  Create a variable object out of
        // it
        return_valobj_sp = ValueObjectConstResult::Create(
            &thread, return_compiler_type, ConstString(""), return_ext);
      }
      return return_valobj_sp;
    }
 
    // Any structure/vector greater than 16 bytes in size is returned in
    // memory. The pointer to that memory is returned 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;
}
 
bool ABISysV_mips64::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("mips64 at-func-entry default");
  unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
  unwind_plan.SetReturnAddressRegister(dwarf_r31);
  return true;
}
 
bool ABISysV_mips64::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
  unwind_plan.Clear();
  unwind_plan.SetRegisterKind(eRegisterKindDWARF);
 
  UnwindPlan::RowSP row(new UnwindPlan::Row);
 
  row->SetUnspecifiedRegistersAreUndefined(true);
  row->GetCFAValue().SetIsRegisterPlusOffset(dwarf_r29, 0);
 
  row->SetRegisterLocationToRegister(dwarf_pc, dwarf_r31, true);
 
  unwind_plan.AppendRow(row);
  unwind_plan.SetSourceName("mips64 default unwind plan");
  unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
  unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
  return true;
}
 
bool ABISysV_mips64::RegisterIsVolatile(const RegisterInfo *reg_info) {
  return !RegisterIsCalleeSaved(reg_info);
}
 
bool ABISysV_mips64::IsSoftFloat(uint32_t fp_flag) const {
  return (fp_flag == lldb_private::ArchSpec::eMIPS_ABI_FP_SOFT);
}
 
bool ABISysV_mips64::RegisterIsCalleeSaved(const RegisterInfo *reg_info) {
  if (reg_info) {
    // Preserved registers are :
    // r16-r23, r28, r29, r30, r31
 
    int reg = ((reg_info->byte_offset) / 8);
 
    bool save = (reg >= 16) && (reg <= 23);
    save |= (reg >= 28) && (reg <= 31);
 
    return save;
  }
  return false;
}
 
void ABISysV_mips64::Initialize() {
  PluginManager::RegisterPlugin(
      GetPluginNameStatic(), "System V ABI for mips64 targets", CreateInstance);
}
 
void ABISysV_mips64::Terminate() {
  PluginManager::UnregisterPlugin(CreateInstance);
}