llvm/lib/Target/M68k/GISel/M68kCallLowering.cpp

//===-- M68kCallLowering.cpp - Call lowering -------------------*- 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
//
//===----------------------------------------------------------------------===//
//
/// \file
/// This file implements the lowering of LLVM calls to machine code calls for
/// GlobalISel.
//
//===----------------------------------------------------------------------===//

#include "M68kCallLowering.h"
#include "M68kISelLowering.h"
#include "M68kInstrInfo.h"
#include "M68kSubtarget.h"
#include "M68kTargetMachine.h"
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/CodeGen/GlobalISel/CallLowering.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/TargetCallingConv.h"

using namespace llvm;

M68kCallLowering::M68kCallLowering(const M68kTargetLowering &TLI)
    : CallLowering(&TLI) {}

struct OutgoingArgHandler : public CallLowering::OutgoingValueHandler {
  OutgoingArgHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
                     MachineInstrBuilder MIB)
      : OutgoingValueHandler(MIRBuilder, MRI), MIB(MIB) {}

  void assignValueToReg(Register ValVReg, Register PhysReg,
                        CCValAssign VA) override {
    MIB.addUse(PhysReg, RegState::Implicit);
    Register ExtReg = extendRegister(ValVReg, VA);
    MIRBuilder.buildCopy(PhysReg, ExtReg);
  }

  void assignValueToAddress(Register ValVReg, Register Addr, LLT MemTy,
                            MachinePointerInfo &MPO, CCValAssign &VA) override {
    llvm_unreachable("unimplemented");
  }

  Register getStackAddress(uint64_t Size, int64_t Offset,
                           MachinePointerInfo &MPO,
                           ISD::ArgFlagsTy Flags) override {
    llvm_unreachable("unimplemented");
  }

  MachineInstrBuilder MIB;
};
bool M68kCallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
                                   const Value *Val, ArrayRef<Register> VRegs,
                                   FunctionLoweringInfo &FLI,
                                   Register SwiftErrorVReg) const {

  auto MIB = MIRBuilder.buildInstrNoInsert(M68k::RTS);
  bool Success = true;
  MachineFunction &MF = MIRBuilder.getMF();
  const Function &F = MF.getFunction();
  MachineRegisterInfo &MRI = MF.getRegInfo();
  const M68kTargetLowering &TLI = *getTLI<M68kTargetLowering>();
  CCAssignFn *AssignFn =
      TLI.getCCAssignFn(F.getCallingConv(), true, F.isVarArg());
  auto &DL = F.getParent()->getDataLayout();
  if (!VRegs.empty()) {
    SmallVector<ArgInfo, 8> SplitArgs;
    ArgInfo OrigArg{VRegs, Val->getType(), 0};
    setArgFlags(OrigArg, AttributeList::ReturnIndex, DL, F);
    splitToValueTypes(OrigArg, SplitArgs, DL, F.getCallingConv());
    OutgoingValueAssigner ArgAssigner(AssignFn);
    OutgoingArgHandler ArgHandler(MIRBuilder, MRI, MIB);
    Success = determineAndHandleAssignments(ArgHandler, ArgAssigner, SplitArgs,
                                            MIRBuilder, F.getCallingConv(),
                                            F.isVarArg());
  }
  MIRBuilder.insertInstr(MIB);
  return Success;
}

bool M68kCallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
                                            const Function &F,
                                            ArrayRef<ArrayRef<Register>> VRegs,
                                            FunctionLoweringInfo &FLI) const {
  MachineFunction &MF = MIRBuilder.getMF();
  MachineRegisterInfo &MRI = MF.getRegInfo();
  const auto &DL = F.getParent()->getDataLayout();
  auto &TLI = *getTLI<M68kTargetLowering>();

  SmallVector<ArgInfo, 8> SplitArgs;
  unsigned I = 0;
  for (const auto &Arg : F.args()) {
    ArgInfo OrigArg{VRegs[I], Arg.getType(), I};
    setArgFlags(OrigArg, I + AttributeList::FirstArgIndex, DL, F);
    splitToValueTypes(OrigArg, SplitArgs, DL, F.getCallingConv());
    ++I;
  }

  CCAssignFn *AssignFn =
      TLI.getCCAssignFn(F.getCallingConv(), false, F.isVarArg());
  IncomingValueAssigner ArgAssigner(AssignFn);
  FormalArgHandler ArgHandler(MIRBuilder, MRI);
  return determineAndHandleAssignments(ArgHandler, ArgAssigner, SplitArgs,
                                       MIRBuilder, F.getCallingConv(),
                                       F.isVarArg());
}

void M68kIncomingValueHandler::assignValueToReg(Register ValVReg,
                                                Register PhysReg,
                                                CCValAssign VA) {
  MIRBuilder.getMRI()->addLiveIn(PhysReg);
  MIRBuilder.getMBB().addLiveIn(PhysReg);
  IncomingValueHandler::assignValueToReg(ValVReg, PhysReg, VA);
}

void M68kIncomingValueHandler::assignValueToAddress(Register ValVReg,
                                                    Register Addr,
                                                    LLT MemTy,
                                                    MachinePointerInfo &MPO,
                                                    CCValAssign &VA) {
  MachineFunction &MF = MIRBuilder.getMF();
  auto *MMO = MF.getMachineMemOperand(MPO, MachineMemOperand::MOLoad, MemTy,
                                      inferAlignFromPtrInfo(MF, MPO));
  MIRBuilder.buildLoad(ValVReg, Addr, *MMO);
}

Register M68kIncomingValueHandler::getStackAddress(uint64_t Size,
                                                   int64_t Offset,
                                                   MachinePointerInfo &MPO,
                                                   ISD::ArgFlagsTy Flags) {
  auto &MFI = MIRBuilder.getMF().getFrameInfo();
  const bool IsImmutable = !Flags.isByVal();
  int FI = MFI.CreateFixedObject(Size, Offset, IsImmutable);
  MPO = MachinePointerInfo::getFixedStack(MIRBuilder.getMF(), FI);

  // Build Frame Index
  llvm::LLT FramePtr = LLT::pointer(
      0, MIRBuilder.getMF().getDataLayout().getPointerSizeInBits());
  MachineInstrBuilder AddrReg = MIRBuilder.buildFrameIndex(FramePtr, FI);
  StackUsed = std::max(StackUsed, Size + Offset);
  return AddrReg.getReg(0);
}

bool M68kCallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
                                 CallLoweringInfo &Info) const {
  return false;
}

bool M68kCallLowering::enableBigEndian() const { return true; }