llvm/lib/Target/RISCV/RISCVFrameLowering.cpp

//===-- RISCVFrameLowering.cpp - RISCV Frame Information ------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the RISCV implementation of TargetFrameLowering class.
//
//===----------------------------------------------------------------------===//

#include "RISCVFrameLowering.h"
#include "RISCVSubtarget.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"

using namespace llvm;

bool RISCVFrameLowering::hasFP(const MachineFunction &MF) const { return true; }

void RISCVFrameLowering::emitPrologue(MachineFunction &MF,
                                      MachineBasicBlock &MBB) const {}

void RISCVFrameLowering::emitEpilogue(MachineFunction &MF,
                                      MachineBasicBlock &MBB) const {}

int RISCVFrameLowering::getFrameIndexReference(const MachineFunction &MF,
                                               int FI,
                                               unsigned &FrameReg) const {
  const MachineFrameInfo &MFI = MF.getFrameInfo();
  const TargetRegisterInfo *RI = MF.getSubtarget().getRegisterInfo();

  // Callee-saved registers should be referenced relative to the stack
  // pointer (positive offset), otherwise use the frame pointer (negative
  // offset).
  const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo();
  int MinCSFI = 0;
  int MaxCSFI = -1;

  int Offset = MFI.getObjectOffset(FI) - getOffsetOfLocalArea() +
               MFI.getOffsetAdjustment();

  if (CSI.size()) {
    MinCSFI = CSI[0].getFrameIdx();
    MaxCSFI = CSI[CSI.size() - 1].getFrameIdx();
  }

  FrameReg = RI->getFrameRegister(MF);
  if (FI >= MinCSFI && FI <= MaxCSFI) {
    FrameReg = RISCV::X2;
    Offset += MF.getFrameInfo().getStackSize();
  }
  return Offset;
}