//===-- VERegisterInfo.cpp - VE Register Information ----------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file contains the VE implementation of the TargetRegisterInfo class.
//
//===----------------------------------------------------------------------===//

#include "VERegisterInfo.h"
#include "VE.h"
#include "VESubtarget.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"

using namespace llvm;

#define GET_REGINFO_TARGET_DESC
#include "VEGenRegisterInfo.inc"

// VE uses %s10 == %lp to keep return address
VERegisterInfo::VERegisterInfo() : VEGenRegisterInfo(VE::SX10) {}

const MCPhysReg *
VERegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
  switch (MF->getFunction().getCallingConv()) {
  case CallingConv::Fast:
    // Being explicit (same as standard CC).
  default:
    return CSR_SaveList;
  case CallingConv::PreserveAll:
    return CSR_preserve_all_SaveList;
  }
}

const uint32_t *VERegisterInfo::getCallPreservedMask(const MachineFunction &MF,
                                                     CallingConv::ID CC) const {
  switch (CC) {
  case CallingConv::Fast:
    // Being explicit (same as standard CC).
  default:
    return CSR_RegMask;
  case CallingConv::PreserveAll:
    return CSR_preserve_all_RegMask;
  }
}

const uint32_t *VERegisterInfo::getNoPreservedMask() const {
  return CSR_NoRegs_RegMask;
}

BitVector VERegisterInfo::getReservedRegs(const MachineFunction &MF) const {
  BitVector Reserved(getNumRegs());

  const Register ReservedRegs[] = {
      VE::SX8,  // Stack limit
      VE::SX9,  // Frame pointer
      VE::SX10, // Link register (return address)
      VE::SX11, // Stack pointer

      // FIXME: maybe not need to be reserved
      VE::SX12, // Outer register
      VE::SX13, // Id register for dynamic linker

      VE::SX14, // Thread pointer
      VE::SX15, // Global offset table register
      VE::SX16, // Procedure linkage table register
      VE::SX17, // Linkage-area register
                // sx18-sx33 are callee-saved registers
                // sx34-sx63 are temporary registers
  };

  for (auto R : ReservedRegs)
    for (MCRegAliasIterator ItAlias(R, this, true); ItAlias.isValid();
         ++ItAlias)
      Reserved.set(*ItAlias);

  // Reserve constant registers.
  Reserved.set(VE::VM0);
  Reserved.set(VE::VMP0);

  return Reserved;
}

bool VERegisterInfo::isConstantPhysReg(MCRegister PhysReg) const {
  switch (PhysReg) {
  case VE::VM0:
  case VE::VMP0:
    return true;
  default:
    return false;
  }
}

const TargetRegisterClass *
VERegisterInfo::getPointerRegClass(const MachineFunction &MF,
                                   unsigned Kind) const {
  return &VE::I64RegClass;
}

static unsigned offsetToDisp(MachineInstr &MI) {
  // Default offset in instruction's operands (reg+reg+imm).
  unsigned OffDisp = 2;

#define RRCAS_multi_cases(NAME) NAME##rir : case NAME##rii

  {
    using namespace llvm::VE;
    switch (MI.getOpcode()) {
    case RRCAS_multi_cases(TS1AML):
    case RRCAS_multi_cases(TS1AMW):
    case RRCAS_multi_cases(CASL):
    case RRCAS_multi_cases(CASW):
      // These instructions use AS format (reg+imm).
      OffDisp = 1;
      break;
    }
  }
#undef RRCAS_multi_cases

  return OffDisp;
}

static void replaceFI(MachineFunction &MF, MachineBasicBlock::iterator II,
                      MachineInstr &MI, const DebugLoc &dl,
                      unsigned FIOperandNum, int Offset, Register FrameReg) {
  // Replace frame index with a frame pointer reference directly.
  // VE has 32 bit offset field, so no need to expand a target instruction.
  // Directly encode it.
  MI.getOperand(FIOperandNum).ChangeToRegister(FrameReg, false);
  MI.getOperand(FIOperandNum + offsetToDisp(MI)).ChangeToImmediate(Offset);
}

void VERegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
                                         int SPAdj, unsigned FIOperandNum,
                                         RegScavenger *RS) const {
  assert(SPAdj == 0 && "Unexpected");

  MachineInstr &MI = *II;
  DebugLoc dl = MI.getDebugLoc();
  int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
  MachineFunction &MF = *MI.getParent()->getParent();
  const VEFrameLowering *TFI = getFrameLowering(MF);

  Register FrameReg;
  int Offset;
  Offset = TFI->getFrameIndexReference(MF, FrameIndex, FrameReg).getFixed();

  Offset += MI.getOperand(FIOperandNum + offsetToDisp(MI)).getImm();

  if (MI.getOpcode() == VE::STQrii) {
    const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
    Register SrcReg = MI.getOperand(3).getReg();
    Register SrcHiReg = getSubReg(SrcReg, VE::sub_even);
    Register SrcLoReg = getSubReg(SrcReg, VE::sub_odd);
    // VE stores HiReg to 8(addr) and LoReg to 0(addr)
    MachineInstr *StMI = BuildMI(*MI.getParent(), II, dl, TII.get(VE::STrii))
                             .addReg(FrameReg)
                             .addImm(0)
                             .addImm(0)
                             .addReg(SrcLoReg);
    replaceFI(MF, II, *StMI, dl, 0, Offset, FrameReg);
    MI.setDesc(TII.get(VE::STrii));
    MI.getOperand(3).setReg(SrcHiReg);
    Offset += 8;
  } else if (MI.getOpcode() == VE::LDQrii) {
    const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
    Register DestReg = MI.getOperand(0).getReg();
    Register DestHiReg = getSubReg(DestReg, VE::sub_even);
    Register DestLoReg = getSubReg(DestReg, VE::sub_odd);
    // VE loads HiReg from 8(addr) and LoReg from 0(addr)
    MachineInstr *StMI =
        BuildMI(*MI.getParent(), II, dl, TII.get(VE::LDrii), DestLoReg)
            .addReg(FrameReg)
            .addImm(0)
            .addImm(0);
    replaceFI(MF, II, *StMI, dl, 1, Offset, FrameReg);
    MI.setDesc(TII.get(VE::LDrii));
    MI.getOperand(0).setReg(DestHiReg);
    Offset += 8;
  }

  replaceFI(MF, II, MI, dl, FIOperandNum, Offset, FrameReg);
}

Register VERegisterInfo::getFrameRegister(const MachineFunction &MF) const {
  return VE::SX9;
}