XtensaFrameLowering.cpp

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//===- XtensaFrameLowering.cpp - Xtensa Frame 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 Xtensa implementation of TargetFrameLowering class.
//
//===----------------------------------------------------------------------===//
 
#include "XtensaFrameLowering.h"
#include "XtensaInstrInfo.h"
#include "XtensaSubtarget.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/IR/Function.h"
 
using namespace llvm;
 
XtensaFrameLowering::XtensaFrameLowering()
    : TargetFrameLowering(TargetFrameLowering::StackGrowsDown, Align(4), 0,
                          Align(4)) {}
 
bool XtensaFrameLowering::hasFP(const MachineFunction &MF) const {
  const MachineFrameInfo &MFI = MF.getFrameInfo();
  return MF.getTarget().Options.DisableFramePointerElim(MF) ||
         MFI.hasVarSizedObjects();
}
 
void XtensaFrameLowering::emitPrologue(MachineFunction &MF,
                                       MachineBasicBlock &MBB) const {}
 
void XtensaFrameLowering::emitEpilogue(MachineFunction &MF,
                                       MachineBasicBlock &MBB) const {}
 
// Eliminate ADJCALLSTACKDOWN, ADJCALLSTACKUP pseudo instructions
MachineBasicBlock::iterator XtensaFrameLowering::eliminateCallFramePseudoInstr(
    MachineFunction &MF, MachineBasicBlock &MBB,
    MachineBasicBlock::iterator I) const {
  const XtensaInstrInfo &TII =
      *static_cast<const XtensaInstrInfo *>(MF.getSubtarget().getInstrInfo());
 
  if (!hasReservedCallFrame(MF)) {
    int64_t Amount = I->getOperand(0).getImm();
 
    if (I->getOpcode() == Xtensa::ADJCALLSTACKDOWN)
      Amount = -Amount;
 
    unsigned SP = Xtensa::SP;
    TII.adjustStackPtr(SP, Amount, MBB, I);
  }
 
  return MBB.erase(I);
}