bool AArch64CallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
const Value *Val, unsigned VReg) const {
MachineInstr *Return = MIRBuilder.buildInstr(AArch64::RET_ReallyLR);
assert(Return && "Unable to build a return instruction?!");
assert(((Val && VReg) || (!Val && !VReg)) && "Return value without a vreg");
if (VReg) {
assert((Val->getType()->isIntegerTy() || Val->getType()->isPointerTy()) &&
"Type not supported yet");
const Function &F = *MIRBuilder.getMF().getFunction();
const DataLayout &DL = F.getParent()->getDataLayout();
unsigned Size = DL.getTypeSizeInBits(Val->getType());
assert((Size == 64 || Size == 32) && "Size not supported yet");
unsigned ResReg = (Size == 32) ? AArch64::W0 : AArch64::X0;
// Set the insertion point to be right before Return.
MIRBuilder.setInstr(*Return, /* Before */ true);
MachineInstr *Copy =
MIRBuilder.buildInstr(TargetOpcode::COPY, ResReg, VReg);
(void)Copy;
assert(Copy->getNextNode() == Return &&
"The insertion did not happen where we expected");
MachineInstrBuilder(MIRBuilder.getMF(), Return)
.addReg(ResReg, RegState::Implicit);
}
return true;
}
MachineInstr *
ReloadIPPass::addReloadIPInstr(MachineFunction::iterator &MFI,
MachineBasicBlock::iterator &MBBI) const {
MachineInstr *MI = MBBI;
StringRef JTPrefix(JumpInstrTables::jump_func_prefix);
switch (MI->getOpcode()) {
case X86::MOV32rm:
if (MI->getNumOperands() > 4 && MI->getOperand(4).isGlobal() &&
MI->getOperand(4).getGlobal()->getName().startswith(JTPrefix)) {
if ((TM->Options.CFIType == CFIntegrity::Add && MI->getNextNode()->getOpcode() == X86::AND32rr)
|| (TM->Options.CFIType == CFIntegrity::Sub && MI->getNextNode()->getOpcode() == X86::SUB32rr)
|| (TM->Options.CFIType == CFIntegrity::Ror && MI->getNextNode()->getOpcode() == X86::SUB32rr)
) {
// MI->dump(); // For debugging
DEBUG(dbgs() << TM->getSubtargetImpl()->getInstrInfo()->getName(MI->getOpcode()) << ": "
<< " Op" << ": "
<< MI->getOperand(4).getGlobal()->getName().str() << "\n";);
return MI;
} else
/// Returns \p New if it's dominated by \p Old, otherwise return \p Old.
/// \p M maintains a map from instruction to its dominating order that satisfies
/// M[A] > M[B] guarantees that A is dominated by B.
/// If \p New is not in \p M, return \p Old. Otherwise if \p Old is null, return
/// \p New.
static MachineInstr *FindDominatedInstruction(MachineInstr &New,
MachineInstr *Old,
const InstOrderMap &M) {
auto NewIter = M.find(&New);
if (NewIter == M.end())
return Old;
if (Old == nullptr)
return &New;
unsigned OrderOld = M.find(Old)->second;
unsigned OrderNew = NewIter->second;
if (OrderOld != OrderNew)
return OrderOld < OrderNew ? &New : Old;
// OrderOld == OrderNew, we need to iterate down from Old to see if it
// can reach New, if yes, New is dominated by Old.
for (MachineInstr *I = Old->getNextNode(); M.find(I)->second == OrderNew;
I = I->getNextNode())
if (I == &New)
return &New;
return Old;
}
MachineInstr *ARCOptAddrMode::tryToCombine(MachineInstr &Ldst) {
assert((Ldst.mayLoad() || Ldst.mayStore()) && "LD/ST instruction expected");
unsigned BasePos, OffsetPos;
LLVM_DEBUG(dbgs() << "[ABAW] tryToCombine " << Ldst);
if (!AII->getBaseAndOffsetPosition(Ldst, BasePos, OffsetPos)) {
LLVM_DEBUG(dbgs() << "[ABAW] Not a recognized load/store\n");
return nullptr;
}
MachineOperand &Base = Ldst.getOperand(BasePos);
MachineOperand &Offset = Ldst.getOperand(OffsetPos);
assert(Base.isReg() && "Base operand must be register");
if (!Offset.isImm()) {
LLVM_DEBUG(dbgs() << "[ABAW] Offset is not immediate\n");
return nullptr;
}
unsigned B = Base.getReg();
if (TargetRegisterInfo::isStackSlot(B) ||
!TargetRegisterInfo::isVirtualRegister(B)) {
LLVM_DEBUG(dbgs() << "[ABAW] Base is not VReg\n");
return nullptr;
}
// TODO: try to generate address preincrement
if (Offset.getImm() != 0) {
LLVM_DEBUG(dbgs() << "[ABAW] Non-zero offset\n");
return nullptr;
}
for (auto &Add : MRI->use_nodbg_instructions(B)) {
int64_t Incr;
if (!isAddConstantOp(Add, Incr))
continue;
if (!isValidLoadStoreOffset(Incr))
continue;
SmallVector<MachineInstr *, 8> Uses;
MachineInstr *MoveTo = canJoinInstructions(&Ldst, &Add, &Uses);
if (!MoveTo)
continue;
if (!canFixPastUses(Uses, Add.getOperand(2), B))
continue;
LLVM_DEBUG(MachineInstr *First = &Ldst; MachineInstr *Last = &Add;
if (MDT->dominates(Last, First)) std::swap(First, Last);
dbgs() << "[ABAW] Instructions " << *First << " and " << *Last
<< " combined\n";
);
MachineInstr *Result = Ldst.getNextNode();
if (MoveTo == &Add) {
Ldst.removeFromParent();
Add.getParent()->insertAfter(Add.getIterator(), &Ldst);
}
if (Result == &Add)
Result = Result->getNextNode();
fixPastUses(Uses, B, Incr);
int NewOpcode = ARC::getPostIncOpcode(Ldst.getOpcode());
assert(NewOpcode > 0 && "No postincrement form found");
unsigned NewBaseReg = Add.getOperand(0).getReg();
changeToAddrMode(Ldst, NewOpcode, NewBaseReg, Add.getOperand(2));
Add.eraseFromParent();
return Result;
}
bool LiveRangeShrink::runOnMachineFunction(MachineFunction &MF) {
if (skipFunction(MF.getFunction()))
return false;
MachineRegisterInfo &MRI = MF.getRegInfo();
LLVM_DEBUG(dbgs() << "**** Analysing " << MF.getName() << '\n');
InstOrderMap IOM;
// Map from register to instruction order (value of IOM) where the
// register is used last. When moving instructions up, we need to
// make sure all its defs (including dead def) will not cross its
// last use when moving up.
DenseMap<unsigned, std::pair<unsigned, MachineInstr *>> UseMap;
for (MachineBasicBlock &MBB : MF) {
if (MBB.empty())
continue;
bool SawStore = false;
BuildInstOrderMap(MBB.begin(), IOM);
UseMap.clear();
for (MachineBasicBlock::iterator Next = MBB.begin(); Next != MBB.end();) {
MachineInstr &MI = *Next;
++Next;
if (MI.isPHI() || MI.isDebugInstr())
continue;
if (MI.mayStore())
SawStore = true;
unsigned CurrentOrder = IOM[&MI];
unsigned Barrier = 0;
MachineInstr *BarrierMI = nullptr;
for (const MachineOperand &MO : MI.operands()) {
if (!MO.isReg() || MO.isDebug())
continue;
if (MO.isUse())
UseMap[MO.getReg()] = std::make_pair(CurrentOrder, &MI);
else if (MO.isDead() && UseMap.count(MO.getReg()))
// Barrier is the last instruction where MO get used. MI should not
// be moved above Barrier.
if (Barrier < UseMap[MO.getReg()].first) {
Barrier = UseMap[MO.getReg()].first;
BarrierMI = UseMap[MO.getReg()].second;
}
}
if (!MI.isSafeToMove(nullptr, SawStore)) {
// If MI has side effects, it should become a barrier for code motion.
// IOM is rebuild from the next instruction to prevent later
// instructions from being moved before this MI.
if (MI.hasUnmodeledSideEffects() && Next != MBB.end()) {
BuildInstOrderMap(Next, IOM);
SawStore = false;
}
continue;
}
const MachineOperand *DefMO = nullptr;
MachineInstr *Insert = nullptr;
// Number of live-ranges that will be shortened. We do not count
// live-ranges that are defined by a COPY as it could be coalesced later.
unsigned NumEligibleUse = 0;
for (const MachineOperand &MO : MI.operands()) {
if (!MO.isReg() || MO.isDead() || MO.isDebug())
continue;
unsigned Reg = MO.getReg();
// Do not move the instruction if it def/uses a physical register,
// unless it is a constant physical register or a noreg.
if (!TargetRegisterInfo::isVirtualRegister(Reg)) {
if (!Reg || MRI.isConstantPhysReg(Reg))
continue;
Insert = nullptr;
break;
}
if (MO.isDef()) {
// Do not move if there is more than one def.
if (DefMO) {
Insert = nullptr;
break;
}
DefMO = &MO;
} else if (MRI.hasOneNonDBGUse(Reg) && MRI.hasOneDef(Reg) && DefMO &&
MRI.getRegClass(DefMO->getReg()) ==
MRI.getRegClass(MO.getReg())) {
// The heuristic does not handle different register classes yet
// (registers of different sizes, looser/tighter constraints). This
// is because it needs more accurate model to handle register
// pressure correctly.
MachineInstr &DefInstr = *MRI.def_instr_begin(Reg);
if (!DefInstr.isCopy())
NumEligibleUse++;
Insert = FindDominatedInstruction(DefInstr, Insert, IOM);
} else {
Insert = nullptr;
break;
}
}
// If Barrier equals IOM[I], traverse forward to find if BarrierMI is
// after Insert, if yes, then we should not hoist.
for (MachineInstr *I = Insert; I && IOM[I] == Barrier;
I = I->getNextNode())
if (I == BarrierMI) {
Insert = nullptr;
break;
}
// Move the instruction when # of shrunk live range > 1.
if (DefMO && Insert && NumEligibleUse > 1 && Barrier <= IOM[Insert]) {
MachineBasicBlock::iterator I = std::next(Insert->getIterator());
// Skip all the PHI and debug instructions.
while (I != MBB.end() && (I->isPHI() || I->isDebugInstr()))
I = std::next(I);
if (I == MI.getIterator())
continue;
// Update the dominator order to be the same as the insertion point.
// We do this to maintain a non-decreasing order without need to update
// all instruction orders after the insertion point.
unsigned NewOrder = IOM[&*I];
IOM[&MI] = NewOrder;
NumInstrsHoistedToShrinkLiveRange++;
// Find MI's debug value following MI.
MachineBasicBlock::iterator EndIter = std::next(MI.getIterator());
if (MI.getOperand(0).isReg())
for (; EndIter != MBB.end() && EndIter->isDebugValue() &&
EndIter->getOperand(0).isReg() &&
EndIter->getOperand(0).getReg() == MI.getOperand(0).getReg();
++EndIter, ++Next)
IOM[&*EndIter] = NewOrder;
MBB.splice(I, &MBB, MI.getIterator(), EndIter);
}
}
}
return false;
}
