//===-- CSKYFrameLowering.cpp - CSKY 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 CSKY implementation of TargetFrameLowering class.
//
//===----------------------------------------------------------------------===//
#include "CSKYFrameLowering.h"
#include "CSKYMachineFunctionInfo.h"
#include "CSKYSubtarget.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/MC/MCDwarf.h"
using namespace llvm;
#define DEBUG_TYPE "csky-frame-lowering"
// Returns the register used to hold the frame pointer.
static Register getFPReg(const CSKYSubtarget &STI) { return CSKY::R8; }
// To avoid the BP value clobbered by a function call, we need to choose a
// callee saved register to save the value.
static Register getBPReg(const CSKYSubtarget &STI) { return CSKY::R7; }
bool CSKYFrameLowering::hasFP(const MachineFunction &MF) const {
const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
const MachineFrameInfo &MFI = MF.getFrameInfo();
return MF.getTarget().Options.DisableFramePointerElim(MF) ||
RegInfo->hasStackRealignment(MF) || MFI.hasVarSizedObjects() ||
MFI.isFrameAddressTaken();
}
bool CSKYFrameLowering::hasBP(const MachineFunction &MF) const {
const MachineFrameInfo &MFI = MF.getFrameInfo();
return MFI.hasVarSizedObjects();
}
// Determines the size of the frame and maximum call frame size.
void CSKYFrameLowering::determineFrameLayout(MachineFunction &MF) const {
MachineFrameInfo &MFI = MF.getFrameInfo();
const CSKYRegisterInfo *RI = STI.getRegisterInfo();
// Get the number of bytes to allocate from the FrameInfo.
uint64_t FrameSize = MFI.getStackSize();
// Get the alignment.
Align StackAlign = getStackAlign();
if (RI->hasStackRealignment(MF)) {
Align MaxStackAlign = std::max(StackAlign, MFI.getMaxAlign());
FrameSize += (MaxStackAlign.value() - StackAlign.value());
StackAlign = MaxStackAlign;
}
// Set Max Call Frame Size
uint64_t MaxCallSize = alignTo(MFI.getMaxCallFrameSize(), StackAlign);
MFI.setMaxCallFrameSize(MaxCallSize);
// Make sure the frame is aligned.
FrameSize = alignTo(FrameSize, StackAlign);
// Update frame info.
MFI.setStackSize(FrameSize);
}
void CSKYFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
CSKYMachineFunctionInfo *CFI = MF.getInfo<CSKYMachineFunctionInfo>();
MachineFrameInfo &MFI = MF.getFrameInfo();
const CSKYRegisterInfo *RI = STI.getRegisterInfo();
const CSKYInstrInfo *TII = STI.getInstrInfo();
MachineBasicBlock::iterator MBBI = MBB.begin();
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
const MachineRegisterInfo &MRI = MF.getRegInfo();
Register FPReg = getFPReg(STI);
Register SPReg = CSKY::R14;
Register BPReg = getBPReg(STI);
// Debug location must be unknown since the first debug location is used
// to determine the end of the prologue.
DebugLoc DL;
if (MF.getFunction().hasFnAttribute("interrupt"))
BuildMI(MBB, MBBI, DL, TII->get(CSKY::NIE));
// Determine the correct frame layout
determineFrameLayout(MF);
// FIXME (note copied from Lanai): This appears to be overallocating. Needs
// investigation. Get the number of bytes to allocate from the FrameInfo.
uint64_t StackSize = MFI.getStackSize();
// Early exit if there is no need to allocate on the stack
if (StackSize == 0 && !MFI.adjustsStack())
return;
const auto &CSI = MFI.getCalleeSavedInfo();
unsigned spillAreaSize = CFI->getCalleeSaveAreaSize();
uint64_t ActualSize = spillAreaSize + CFI->getVarArgsSaveSize();
// First part stack allocation.
adjustReg(MBB, MBBI, DL, SPReg, SPReg, -(static_cast<int64_t>(ActualSize)),
MachineInstr::NoFlags);
// Emit ".cfi_def_cfa_offset FirstSPAdjustAmount"
unsigned CFIIndex =
MF.addFrameInst(MCCFIInstruction::cfiDefCfaOffset(nullptr, ActualSize));
BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
// The frame pointer is callee-saved, and code has been generated for us to
// save it to the stack. We need to skip over the storing of callee-saved
// registers as the frame pointer must be modified after it has been saved
// to the stack, not before.
// FIXME: assumes exactly one instruction is used to save each callee-saved
// register.
std::advance(MBBI, CSI.size());
// Iterate over list of callee-saved registers and emit .cfi_offset
// directives.
for (const auto &Entry : CSI) {
int64_t Offset = MFI.getObjectOffset(Entry.getFrameIdx());
Register Reg = Entry.getReg();
unsigned Num = TRI->getRegSizeInBits(Reg, MRI) / 32;
for (unsigned i = 0; i < Num; i++) {
unsigned CFIIndex = MF.addFrameInst(MCCFIInstruction::createOffset(
nullptr, RI->getDwarfRegNum(Reg, true) + i, Offset + i * 4));
BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
}
// Generate new FP.
if (hasFP(MF)) {
BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::COPY), FPReg)
.addReg(SPReg)
.setMIFlag(MachineInstr::FrameSetup);
// Emit ".cfi_def_cfa_register $fp"
unsigned CFIIndex = MF.addFrameInst(MCCFIInstruction::createDefCfaRegister(
nullptr, RI->getDwarfRegNum(FPReg, true)));
BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
// Second part stack allocation.
adjustReg(MBB, MBBI, DL, SPReg, SPReg,
-(static_cast<int64_t>(StackSize - ActualSize)),
MachineInstr::NoFlags);
// Realign Stack
const CSKYRegisterInfo *RI = STI.getRegisterInfo();
if (RI->hasStackRealignment(MF)) {
Align MaxAlignment = MFI.getMaxAlign();
const CSKYInstrInfo *TII = STI.getInstrInfo();
if (STI.hasE2() && isUInt<12>(~(-(int)MaxAlignment.value()))) {
BuildMI(MBB, MBBI, DL, TII->get(CSKY::ANDNI32), SPReg)
.addReg(SPReg)
.addImm(~(-(int)MaxAlignment.value()));
} else {
unsigned ShiftAmount = Log2(MaxAlignment);
if (STI.hasE2()) {
Register VR =
MF.getRegInfo().createVirtualRegister(&CSKY::GPRRegClass);
BuildMI(MBB, MBBI, DL, TII->get(CSKY::LSRI32), VR)
.addReg(SPReg)
.addImm(ShiftAmount);
BuildMI(MBB, MBBI, DL, TII->get(CSKY::LSLI32), SPReg)
.addReg(VR)
.addImm(ShiftAmount);
} else {
Register VR =
MF.getRegInfo().createVirtualRegister(&CSKY::mGPRRegClass);
BuildMI(MBB, MBBI, DL, TII->get(CSKY::MOV16), VR).addReg(SPReg);
BuildMI(MBB, MBBI, DL, TII->get(CSKY::LSRI16), VR)
.addReg(VR)
.addImm(ShiftAmount);
BuildMI(MBB, MBBI, DL, TII->get(CSKY::LSLI16), VR)
.addReg(VR)
.addImm(ShiftAmount);
BuildMI(MBB, MBBI, DL, TII->get(CSKY::MOV16), SPReg).addReg(VR);
}
}
}
// FP will be used to restore the frame in the epilogue, so we need
// another base register BP to record SP after re-alignment. SP will
// track the current stack after allocating variable sized objects.
if (hasBP(MF)) {
// move BP, SP
BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::COPY), BPReg).addReg(SPReg);
}
} else {
adjustReg(MBB, MBBI, DL, SPReg, SPReg,
-(static_cast<int64_t>(StackSize - ActualSize)),
MachineInstr::NoFlags);
// Emit ".cfi_def_cfa_offset StackSize"
unsigned CFIIndex = MF.addFrameInst(
MCCFIInstruction::cfiDefCfaOffset(nullptr, MFI.getStackSize()));
BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
}
void CSKYFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
CSKYMachineFunctionInfo *CFI = MF.getInfo<CSKYMachineFunctionInfo>();
MachineFrameInfo &MFI = MF.getFrameInfo();
Register FPReg = getFPReg(STI);
Register SPReg = CSKY::R14;
// Get the insert location for the epilogue. If there were no terminators in
// the block, get the last instruction.
MachineBasicBlock::iterator MBBI = MBB.end();
DebugLoc DL;
if (!MBB.empty()) {
MBBI = MBB.getFirstTerminator();
if (MBBI == MBB.end())
MBBI = MBB.getLastNonDebugInstr();
DL = MBBI->getDebugLoc();
// If this is not a terminator, the actual insert location should be after
// the last instruction.
if (!MBBI->isTerminator())
MBBI = std::next(MBBI);
}
const auto &CSI = MFI.getCalleeSavedInfo();
uint64_t StackSize = MFI.getStackSize();
uint64_t ActualSize =
CFI->getCalleeSaveAreaSize() + CFI->getVarArgsSaveSize();
// Skip to before the restores of callee-saved registers
// FIXME: assumes exactly one instruction is used to restore each
// callee-saved register.
auto LastFrameDestroy = MBBI;
if (!CSI.empty())
LastFrameDestroy = std::prev(MBBI, CSI.size());
if (hasFP(MF)) {
const CSKYInstrInfo *TII = STI.getInstrInfo();
BuildMI(MBB, LastFrameDestroy, DL, TII->get(TargetOpcode::COPY), SPReg)
.addReg(FPReg)
.setMIFlag(MachineInstr::NoFlags);
} else {
adjustReg(MBB, LastFrameDestroy, DL, SPReg, SPReg, (StackSize - ActualSize),
MachineInstr::FrameDestroy);
}
adjustReg(MBB, MBBI, DL, SPReg, SPReg, ActualSize,
MachineInstr::FrameDestroy);
}
static unsigned EstimateFunctionSizeInBytes(const MachineFunction &MF,
const CSKYInstrInfo &TII) {
unsigned FnSize = 0;
for (auto &MBB : MF) {
for (auto &MI : MBB)
FnSize += TII.getInstSizeInBytes(MI);
}
FnSize += MF.getConstantPool()->getConstants().size() * 4;
return FnSize;
}
static unsigned estimateRSStackSizeLimit(MachineFunction &MF,
const CSKYSubtarget &STI) {
unsigned Limit = (1 << 12) - 1;
for (auto &MBB : MF) {
for (auto &MI : MBB) {
if (MI.isDebugInstr())
continue;
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
if (!MI.getOperand(i).isFI())
continue;
if (MI.getOpcode() == CSKY::SPILL_CARRY ||
MI.getOpcode() == CSKY::RESTORE_CARRY ||
MI.getOpcode() == CSKY::STORE_PAIR ||
MI.getOpcode() == CSKY::LOAD_PAIR) {
Limit = std::min(Limit, ((1U << 12) - 1) * 4);
break;
}
if (MI.getOpcode() == CSKY::ADDI32) {
Limit = std::min(Limit, (1U << 12));
break;
}
if (MI.getOpcode() == CSKY::ADDI16XZ) {
Limit = std::min(Limit, (1U << 3));
break;
}
// ADDI16 will not require an extra register,
// it can reuse the destination.
if (MI.getOpcode() == CSKY::ADDI16)
break;
// Otherwise check the addressing mode.
switch (MI.getDesc().TSFlags & CSKYII::AddrModeMask) {
default:
LLVM_DEBUG(MI.dump());
llvm_unreachable(
"Unhandled addressing mode in stack size limit calculation");
case CSKYII::AddrMode32B:
Limit = std::min(Limit, (1U << 12) - 1);
break;
case CSKYII::AddrMode32H:
Limit = std::min(Limit, ((1U << 12) - 1) * 2);
break;
case CSKYII::AddrMode32WD:
Limit = std::min(Limit, ((1U << 12) - 1) * 4);
break;
case CSKYII::AddrMode16B:
Limit = std::min(Limit, (1U << 5) - 1);
break;
case CSKYII::AddrMode16H:
Limit = std::min(Limit, ((1U << 5) - 1) * 2);
break;
case CSKYII::AddrMode16W:
Limit = std::min(Limit, ((1U << 5) - 1) * 4);
break;
case CSKYII::AddrMode32SDF:
Limit = std::min(Limit, ((1U << 8) - 1) * 4);
break;
}
break; // At most one FI per instruction
}
}
}
return Limit;
}
void CSKYFrameLowering::determineCalleeSaves(MachineFunction &MF,
BitVector &SavedRegs,
RegScavenger *RS) const {
TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
CSKYMachineFunctionInfo *CFI = MF.getInfo<CSKYMachineFunctionInfo>();
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
const CSKYInstrInfo *TII = STI.getInstrInfo();
const MachineRegisterInfo &MRI = MF.getRegInfo();
MachineFrameInfo &MFI = MF.getFrameInfo();
if (hasFP(MF))
SavedRegs.set(CSKY::R8);
// Mark BP as used if function has dedicated base pointer.
if (hasBP(MF))
SavedRegs.set(CSKY::R7);
// If interrupt is enabled and there are calls in the handler,
// unconditionally save all Caller-saved registers and
// all FP registers, regardless whether they are used.
if (MF.getFunction().hasFnAttribute("interrupt") && MFI.hasCalls()) {
static const MCPhysReg CSRegs[] = {CSKY::R0, CSKY::R1, CSKY::R2, CSKY::R3,
CSKY::R12, CSKY::R13, 0};
for (unsigned i = 0; CSRegs[i]; ++i)
SavedRegs.set(CSRegs[i]);
if (STI.hasHighRegisters()) {
static const MCPhysReg CSHRegs[] = {CSKY::R18, CSKY::R19, CSKY::R20,
CSKY::R21, CSKY::R22, CSKY::R23,
CSKY::R24, CSKY::R25, 0};
for (unsigned i = 0; CSHRegs[i]; ++i)
SavedRegs.set(CSHRegs[i]);
}
static const MCPhysReg CSF32Regs[] = {
CSKY::F8_32, CSKY::F9_32, CSKY::F10_32,
CSKY::F11_32, CSKY::F12_32, CSKY::F13_32,
CSKY::F14_32, CSKY::F15_32, 0};
static const MCPhysReg CSF64Regs[] = {
CSKY::F8_64, CSKY::F9_64, CSKY::F10_64,
CSKY::F11_64, CSKY::F12_64, CSKY::F13_64,
CSKY::F14_64, CSKY::F15_64, 0};
const MCPhysReg *FRegs = NULL;
if (STI.hasFPUv2DoubleFloat() || STI.hasFPUv3DoubleFloat())
FRegs = CSF64Regs;
else if (STI.hasFPUv2SingleFloat() || STI.hasFPUv3SingleFloat())
FRegs = CSF32Regs;
if (FRegs != NULL) {
const MCPhysReg *Regs = MF.getRegInfo().getCalleeSavedRegs();
for (unsigned i = 0; Regs[i]; ++i)
if (CSKY::FPR32RegClass.contains(Regs[i]) ||
CSKY::FPR64RegClass.contains(Regs[i])) {
unsigned x = 0;
for (; FRegs[x]; ++x)
if (FRegs[x] == Regs[i])
break;
if (FRegs[x] == 0)
SavedRegs.set(Regs[i]);
}
}
}
unsigned CSStackSize = 0;
for (unsigned Reg : SavedRegs.set_bits()) {
auto RegSize = TRI->getRegSizeInBits(Reg, MRI) / 8;
CSStackSize += RegSize;
}
CFI->setCalleeSaveAreaSize(CSStackSize);
uint64_t Limit = estimateRSStackSizeLimit(MF, STI);
bool BigFrame = (MFI.estimateStackSize(MF) + CSStackSize >= Limit);
if (BigFrame || CFI->isCRSpilled() || !STI.hasE2()) {
const TargetRegisterClass *RC = &CSKY::GPRRegClass;
unsigned size = TRI->getSpillSize(*RC);
Align align = TRI->getSpillAlign(*RC);
RS->addScavengingFrameIndex(MFI.CreateStackObject(size, align, false));
}
unsigned FnSize = EstimateFunctionSizeInBytes(MF, *TII);
// Force R15 to be spilled if the function size is > 65534. This enables
// use of BSR to implement far jump.
if (FnSize >= ((1 << (16 - 1)) * 2))
SavedRegs.set(CSKY::R15);
CFI->setLRIsSpilled(SavedRegs.test(CSKY::R15));
}
// Not preserve stack space within prologue for outgoing variables when the
// function contains variable size objects and let eliminateCallFramePseudoInstr
// preserve stack space for it.
bool CSKYFrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
return !MF.getFrameInfo().hasVarSizedObjects();
}
bool CSKYFrameLowering::spillCalleeSavedRegisters(
MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
ArrayRef<CalleeSavedInfo> CSI, const TargetRegisterInfo *TRI) const {
if (CSI.empty())
return true;
MachineFunction *MF = MBB.getParent();
const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
DebugLoc DL;
if (MI != MBB.end() && !MI->isDebugInstr())
DL = MI->getDebugLoc();
for (auto &CS : CSI) {
// Insert the spill to the stack frame.
Register Reg = CS.getReg();
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.storeRegToStackSlot(MBB, MI, Reg, true, CS.getFrameIdx(), RC, TRI,
Register());
}
return true;
}
bool CSKYFrameLowering::restoreCalleeSavedRegisters(
MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
MutableArrayRef<CalleeSavedInfo> CSI, const TargetRegisterInfo *TRI) const {
if (CSI.empty())
return true;
MachineFunction *MF = MBB.getParent();
const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
DebugLoc DL;
if (MI != MBB.end() && !MI->isDebugInstr())
DL = MI->getDebugLoc();
for (auto &CS : reverse(CSI)) {
Register Reg = CS.getReg();
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.loadRegFromStackSlot(MBB, MI, Reg, CS.getFrameIdx(), RC, TRI,
Register());
assert(MI != MBB.begin() && "loadRegFromStackSlot didn't insert any code!");
}
return true;
}
// Eliminate ADJCALLSTACKDOWN, ADJCALLSTACKUP pseudo instructions.
MachineBasicBlock::iterator CSKYFrameLowering::eliminateCallFramePseudoInstr(
MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const {
Register SPReg = CSKY::R14;
DebugLoc DL = MI->getDebugLoc();
if (!hasReservedCallFrame(MF)) {
// If space has not been reserved for a call frame, ADJCALLSTACKDOWN and
// ADJCALLSTACKUP must be converted to instructions manipulating the stack
// pointer. This is necessary when there is a variable length stack
// allocation (e.g. alloca), which means it's not possible to allocate
// space for outgoing arguments from within the function prologue.
int64_t Amount = MI->getOperand(0).getImm();
if (Amount != 0) {
// Ensure the stack remains aligned after adjustment.
Amount = alignSPAdjust(Amount);
if (MI->getOpcode() == CSKY::ADJCALLSTACKDOWN)
Amount = -Amount;
adjustReg(MBB, MI, DL, SPReg, SPReg, Amount, MachineInstr::NoFlags);
}
}
return MBB.erase(MI);
}
void CSKYFrameLowering::adjustReg(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
const DebugLoc &DL, Register DestReg,
Register SrcReg, int64_t Val,
MachineInstr::MIFlag Flag) const {
const CSKYInstrInfo *TII = STI.getInstrInfo();
if (DestReg == SrcReg && Val == 0)
return;
// TODO: Add 16-bit instruction support with immediate num
if (STI.hasE2() && isUInt<12>(std::abs(Val) - 1)) {
BuildMI(MBB, MBBI, DL, TII->get(Val < 0 ? CSKY::SUBI32 : CSKY::ADDI32),
DestReg)
.addReg(SrcReg)
.addImm(std::abs(Val))
.setMIFlag(Flag);
} else if (!STI.hasE2() && isShiftedUInt<7, 2>(std::abs(Val))) {
BuildMI(MBB, MBBI, DL,
TII->get(Val < 0 ? CSKY::SUBI16SPSP : CSKY::ADDI16SPSP), CSKY::R14)
.addReg(CSKY::R14, RegState::Kill)
.addImm(std::abs(Val))
.setMIFlag(Flag);
} else {
unsigned Op = 0;
if (STI.hasE2()) {
Op = Val < 0 ? CSKY::SUBU32 : CSKY::ADDU32;
} else {
assert(SrcReg == DestReg);
Op = Val < 0 ? CSKY::SUBU16XZ : CSKY::ADDU16XZ;
}
Register ScratchReg = TII->movImm(MBB, MBBI, DL, std::abs(Val), Flag);
BuildMI(MBB, MBBI, DL, TII->get(Op), DestReg)
.addReg(SrcReg)
.addReg(ScratchReg, RegState::Kill)
.setMIFlag(Flag);
}
}
StackOffset
CSKYFrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI,
Register &FrameReg) const {
const CSKYMachineFunctionInfo *CFI = MF.getInfo<CSKYMachineFunctionInfo>();
const MachineFrameInfo &MFI = MF.getFrameInfo();
const TargetRegisterInfo *RI = MF.getSubtarget().getRegisterInfo();
const auto &CSI = MFI.getCalleeSavedInfo();
int MinCSFI = 0;
int MaxCSFI = -1;
int Offset = MFI.getObjectOffset(FI) + MFI.getOffsetAdjustment();
if (CSI.size()) {
MinCSFI = CSI[0].getFrameIdx();
MaxCSFI = CSI[CSI.size() - 1].getFrameIdx();
}
if (FI >= MinCSFI && FI <= MaxCSFI) {
FrameReg = CSKY::R14;
Offset += CFI->getVarArgsSaveSize() + CFI->getCalleeSaveAreaSize();
} else if (RI->hasStackRealignment(MF)) {
assert(hasFP(MF));
if (!MFI.isFixedObjectIndex(FI)) {
FrameReg = hasBP(MF) ? getBPReg(STI) : CSKY::R14;
Offset += MFI.getStackSize();
} else {
FrameReg = getFPReg(STI);
Offset += CFI->getVarArgsSaveSize() + CFI->getCalleeSaveAreaSize();
}
} else {
if (MFI.isFixedObjectIndex(FI) && hasFP(MF)) {
FrameReg = getFPReg(STI);
Offset += CFI->getVarArgsSaveSize() + CFI->getCalleeSaveAreaSize();
} else {
FrameReg = hasBP(MF) ? getBPReg(STI) : CSKY::R14;
Offset += MFI.getStackSize();
}
}
return StackOffset::getFixed(Offset);
}