text: //=======- NVPTXFrameLowering.cpp - NVPTX Frame Information ---*- C++ -*-=====//
  //
  // 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 NVPTX implementation of TargetFrameLowering class.
  //
  //===----------------------------------------------------------------------===//
  
  #include "NVPTXFrameLowering.h"
  #include "NVPTX.h"
  #include "NVPTXRegisterInfo.h"
  #include "NVPTXSubtarget.h"
  #include "NVPTXTargetMachine.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/MC/MachineLocation.h"
  
  using namespace llvm;
  
  NVPTXFrameLowering::NVPTXFrameLowering()
      : TargetFrameLowering(TargetFrameLowering::StackGrowsUp, Align(8), 0) {}
  
  bool NVPTXFrameLowering::hasFP(const MachineFunction &MF) const { return true; }
  
  void NVPTXFrameLowering::emitPrologue(MachineFunction &MF,
                                        MachineBasicBlock &MBB) const {
    if (MF.getFrameInfo().hasStackObjects()) {
      assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
      MachineInstr *MI = &MBB.front();
      MachineRegisterInfo &MR = MF.getRegInfo();
  
      // This instruction really occurs before first instruction
      // in the BB, so giving it no debug location.
      DebugLoc dl = DebugLoc();
  
      // Emits
      //   mov %SPL, %depot;
      //   cvta.local %SP, %SPL;
      // for local address accesses in MF.
      bool Is64Bit =
          static_cast<const NVPTXTargetMachine &>(MF.getTarget()).is64Bit();
      unsigned CvtaLocalOpcode =
          (Is64Bit ? NVPTX::cvta_local_yes_64 : NVPTX::cvta_local_yes);
      unsigned MovDepotOpcode =
          (Is64Bit ? NVPTX::MOV_DEPOT_ADDR_64 : NVPTX::MOV_DEPOT_ADDR);
      if (!MR.use_empty(NVPTX::VRFrame)) {
        // If %SP is not used, do not bother emitting "cvta.local %SP, %SPL".
        MI = BuildMI(MBB, MI, dl,
                     MF.getSubtarget().getInstrInfo()->get(CvtaLocalOpcode),
                     NVPTX::VRFrame)
                 .addReg(NVPTX::VRFrameLocal);
      }
      BuildMI(MBB, MI, dl, MF.getSubtarget().getInstrInfo()->get(MovDepotOpcode),
              NVPTX::VRFrameLocal)
          .addImm(MF.getFunctionNumber());
    }
  }
  
  int NVPTXFrameLowering::getFrameIndexReference(const MachineFunction &MF,
                                                 int FI,
                                                 unsigned &FrameReg) const {
    const MachineFrameInfo &MFI = MF.getFrameInfo();
    FrameReg = NVPTX::VRDepot;
    return MFI.getObjectOffset(FI) - getOffsetOfLocalArea();
  }
  
  void NVPTXFrameLowering::emitEpilogue(MachineFunction &MF,
                                        MachineBasicBlock &MBB) const {}
  
  // This function eliminates ADJCALLSTACKDOWN,
  // ADJCALLSTACKUP pseudo instructions
  MachineBasicBlock::iterator NVPTXFrameLowering::eliminateCallFramePseudoInstr(
      MachineFunction &MF, MachineBasicBlock &MBB,
      MachineBasicBlock::iterator I) const {
    // Simply discard ADJCALLSTACKDOWN,
    // ADJCALLSTACKUP instructions.
    return MBB.erase(I);
  }
  