void XCoreFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineModuleInfo *MMI = &MF.getMMI();
const MCRegisterInfo *MRI = MMI->getContext().getRegisterInfo();
const XCoreInstrInfo &TII = *MF.getSubtarget<XCoreSubtarget>().getInstrInfo();
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
// Debug location must be unknown since the first debug location is used
// to determine the end of the prologue.
DebugLoc dl;
if (MFI->getMaxAlignment() > getStackAlignment())
report_fatal_error("emitPrologue unsupported alignment: "
+ Twine(MFI->getMaxAlignment()));
const AttributeSet &PAL = MF.getFunction()->getAttributes();
if (PAL.hasAttrSomewhere(Attribute::Nest))
BuildMI(MBB, MBBI, dl, TII.get(XCore::LDWSP_ru6), XCore::R11).addImm(0);
// FIX: Needs addMemOperand() but can't use getFixedStack() or getStack().
// Work out frame sizes.
// We will adjust the SP in stages towards the final FrameSize.
assert(MFI->getStackSize()%4 == 0 && "Misaligned frame size");
const int FrameSize = MFI->getStackSize() / 4;
int Adjusted = 0;
bool saveLR = XFI->hasLRSpillSlot();
bool UseENTSP = saveLR && FrameSize
&& (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0);
if (UseENTSP)
saveLR = false;
bool FP = hasFP(MF);
bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(MF);
if (UseENTSP) {
// Allocate space on the stack at the same time as saving LR.
Adjusted = (FrameSize > MaxImmU16) ? MaxImmU16 : FrameSize;
int Opcode = isImmU6(Adjusted) ? XCore::ENTSP_u6 : XCore::ENTSP_lu6;
MBB.addLiveIn(XCore::LR);
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opcode));
MIB.addImm(Adjusted);
MIB->addRegisterKilled(XCore::LR, MF.getSubtarget().getRegisterInfo(),
true);
if (emitFrameMoves) {
EmitDefCfaOffset(MBB, MBBI, dl, TII, MMI, Adjusted*4);
unsigned DRegNum = MRI->getDwarfRegNum(XCore::LR, true);
EmitCfiOffset(MBB, MBBI, dl, TII, MMI, DRegNum, 0);
}
}
// If necessary, save LR and FP to the stack, as we EXTSP.
SmallVector<StackSlotInfo,2> SpillList;
GetSpillList(SpillList, MFI, XFI, saveLR, FP);
// We want the nearest (negative) offsets first, so reverse list.
std::reverse(SpillList.begin(), SpillList.end());
for (unsigned i = 0, e = SpillList.size(); i != e; ++i) {
assert(SpillList[i].Offset % 4 == 0 && "Misaligned stack offset");
assert(SpillList[i].Offset <= 0 && "Unexpected positive stack offset");
int OffsetFromTop = - SpillList[i].Offset/4;
IfNeededExtSP(MBB, MBBI, dl, TII, MMI, OffsetFromTop, Adjusted, FrameSize,
emitFrameMoves);
int Offset = Adjusted - OffsetFromTop;
int Opcode = isImmU6(Offset) ? XCore::STWSP_ru6 : XCore::STWSP_lru6;
MBB.addLiveIn(SpillList[i].Reg);
BuildMI(MBB, MBBI, dl, TII.get(Opcode))
.addReg(SpillList[i].Reg, RegState::Kill)
.addImm(Offset)
.addMemOperand(getFrameIndexMMO(MBB, SpillList[i].FI,
MachineMemOperand::MOStore));
if (emitFrameMoves) {
unsigned DRegNum = MRI->getDwarfRegNum(SpillList[i].Reg, true);
EmitCfiOffset(MBB, MBBI, dl, TII, MMI, DRegNum, SpillList[i].Offset);
}
}
// Complete any remaining Stack adjustment.
IfNeededExtSP(MBB, MBBI, dl, TII, MMI, FrameSize, Adjusted, FrameSize,
emitFrameMoves);
assert(Adjusted==FrameSize && "IfNeededExtSP has not completed adjustment");
if (FP) {
// Set the FP from the SP.
BuildMI(MBB, MBBI, dl, TII.get(XCore::LDAWSP_ru6), FramePtr).addImm(0);
if (emitFrameMoves)
EmitDefCfaRegister(MBB, MBBI, dl, TII, MMI,
MRI->getDwarfRegNum(FramePtr, true));
}
if (emitFrameMoves) {
// Frame moves for callee saved.
for (const auto &SpillLabel : XFI->getSpillLabels()) {
MachineBasicBlock::iterator Pos = SpillLabel.first;
++Pos;
const CalleeSavedInfo &CSI = SpillLabel.second;
int Offset = MFI->getObjectOffset(CSI.getFrameIdx());
unsigned DRegNum = MRI->getDwarfRegNum(CSI.getReg(), true);
EmitCfiOffset(MBB, Pos, dl, TII, MMI, DRegNum, Offset);
}
if (XFI->hasEHSpillSlot()) {
// The unwinder requires stack slot & CFI offsets for the exception info.
// We do not save/spill these registers.
SmallVector<StackSlotInfo,2> SpillList;
GetEHSpillList(SpillList, MFI, XFI,
MF.getSubtarget().getTargetLowering());
assert(SpillList.size()==2 && "Unexpected SpillList size");
EmitCfiOffset(MBB, MBBI, dl, TII, MMI,
MRI->getDwarfRegNum(SpillList[0].Reg, true),
SpillList[0].Offset);
EmitCfiOffset(MBB, MBBI, dl, TII, MMI,
MRI->getDwarfRegNum(SpillList[1].Reg, true),
SpillList[1].Offset);
}
}
}
