using namespace llvm;
CriticalAntiDepBreaker::
-CriticalAntiDepBreaker(MachineFunction& MFi) :
+CriticalAntiDepBreaker(MachineFunction& MFi, const RegisterClassInfo &RCI) :
AntiDepBreaker(), MF(MFi),
MRI(MF.getRegInfo()),
TII(MF.getTarget().getInstrInfo()),
TRI(MF.getTarget().getRegisterInfo()),
- AllocatableSet(TRI->getAllocatableSet(MF)),
+ RegClassInfo(RCI),
Classes(TRI->getNumRegs(), static_cast<const TargetRegisterClass *>(0)),
KillIndices(TRI->getNumRegs(), 0),
DefIndices(TRI->getNumRegs(), 0) {}
return;
assert(Count < InsertPosIndex && "Instruction index out of expected range!");
- // Any register which was defined within the previous scheduling region
- // may have been rescheduled and its lifetime may overlap with registers
- // in ways not reflected in our current liveness state. For each such
- // register, adjust the liveness state to be conservatively correct.
- for (unsigned Reg = 0; Reg != TRI->getNumRegs(); ++Reg)
- if (DefIndices[Reg] < InsertPosIndex && DefIndices[Reg] >= Count) {
- assert(KillIndices[Reg] == ~0u && "Clobbered register is live!");
-
- // Mark this register to be non-renamable.
+ for (unsigned Reg = 0; Reg != TRI->getNumRegs(); ++Reg) {
+ if (KillIndices[Reg] != ~0u) {
+ // If Reg is currently live, then mark that it can't be renamed as
+ // we don't know the extent of its live-range anymore (now that it
+ // has been scheduled).
+ Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
+ KillIndices[Reg] = Count;
+ } else if (DefIndices[Reg] < InsertPosIndex && DefIndices[Reg] >= Count) {
+ // Any register which was defined within the previous scheduling region
+ // may have been rescheduled and its lifetime may overlap with registers
+ // in ways not reflected in our current liveness state. For each such
+ // register, adjust the liveness state to be conservatively correct.
Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
// Move the def index to the end of the previous region, to reflect
// that the def could theoretically have been scheduled at the end.
DefIndices[Reg] = InsertPosIndex;
}
+ }
PrescanInstruction(MI);
ScanInstruction(MI, Count);
// that have special allocation requirements. Also assume all registers
// used in a call must not be changed (ABI).
// FIXME: The issue with predicated instruction is more complex. We are being
- // conservatively here because the kill markers cannot be trusted after
+ // conservative here because the kill markers cannot be trusted after
// if-conversion:
// %R6<def> = LDR %SP, %reg0, 92, pred:14, pred:%reg0; mem:LD4[FixedStack14]
// ...
const TargetRegisterClass *NewRC = 0;
if (i < MI->getDesc().getNumOperands())
- NewRC = MI->getDesc().OpInfo[i].getRegClass(TRI);
+ NewRC = TII->getRegClass(MI->getDesc(), i, TRI);
// For now, only allow the register to be changed if its register
// class is consistent across all uses.
const TargetRegisterClass *NewRC = 0;
if (i < MI->getDesc().getNumOperands())
- NewRC = MI->getDesc().OpInfo[i].getRegClass(TRI);
+ NewRC = TII->getRegClass(MI->getDesc(), i, TRI);
// For now, only allow the register to be changed if its register
// class is consistent across all uses.
}
}
+// Check all machine operands that reference the antidependent register and must
+// be replaced by NewReg. Return true if any of their parent instructions may
+// clobber the new register.
+//
+// Note: AntiDepReg may be referenced by a two-address instruction such that
+// it's use operand is tied to a def operand. We guard against the case in which
+// the two-address instruction also defines NewReg, as may happen with
+// pre/postincrement loads. In this case, both the use and def operands are in
+// RegRefs because the def is inserted by PrescanInstruction and not erased
+// during ScanInstruction. So checking for an instructions with definitions of
+// both NewReg and AntiDepReg covers it.
+bool
+CriticalAntiDepBreaker::isNewRegClobberedByRefs(RegRefIter RegRefBegin,
+ RegRefIter RegRefEnd,
+ unsigned NewReg)
+{
+ for (RegRefIter I = RegRefBegin; I != RegRefEnd; ++I ) {
+ MachineOperand *RefOper = I->second;
+
+ // Don't allow the instruction defining AntiDepReg to earlyclobber its
+ // operands, in case they may be assigned to NewReg. In this case antidep
+ // breaking must fail, but it's too rare to bother optimizing.
+ if (RefOper->isDef() && RefOper->isEarlyClobber())
+ return true;
+
+ // Handle cases in which this instructions defines NewReg.
+ MachineInstr *MI = RefOper->getParent();
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &CheckOper = MI->getOperand(i);
+
+ if (!CheckOper.isReg() || !CheckOper.isDef() ||
+ CheckOper.getReg() != NewReg)
+ continue;
+
+ // Don't allow the instruction to define NewReg and AntiDepReg.
+ // When AntiDepReg is renamed it will be an illegal op.
+ if (RefOper->isDef())
+ return true;
+
+ // Don't allow an instruction using AntiDepReg to be earlyclobbered by
+ // NewReg
+ if (CheckOper.isEarlyClobber())
+ return true;
+
+ // Don't allow inline asm to define NewReg at all. Who know what it's
+ // doing with it.
+ if (MI->isInlineAsm())
+ return true;
+ }
+ }
+ return false;
+}
+
unsigned
-CriticalAntiDepBreaker::findSuitableFreeRegister(MachineInstr *MI,
+CriticalAntiDepBreaker::findSuitableFreeRegister(RegRefIter RegRefBegin,
+ RegRefIter RegRefEnd,
unsigned AntiDepReg,
unsigned LastNewReg,
const TargetRegisterClass *RC)
{
- for (TargetRegisterClass::iterator R = RC->allocation_order_begin(MF),
- RE = RC->allocation_order_end(MF); R != RE; ++R) {
- unsigned NewReg = *R;
- // Don't consider non-allocatable registers
- if (!AllocatableSet.test(NewReg)) continue;
+ ArrayRef<unsigned> Order = RegClassInfo.getOrder(RC);
+ for (unsigned i = 0; i != Order.size(); ++i) {
+ unsigned NewReg = Order[i];
// Don't replace a register with itself.
if (NewReg == AntiDepReg) continue;
// Don't replace a register with one that was recently used to repair
// an anti-dependence with this AntiDepReg, because that would
// re-introduce that anti-dependence.
if (NewReg == LastNewReg) continue;
- // If the instruction already has a def of the NewReg, it's not suitable.
- // For example, Instruction with multiple definitions can result in this
- // condition.
- if (MI->modifiesRegister(NewReg, TRI)) continue;
+ // If any instructions that define AntiDepReg also define the NewReg, it's
+ // not suitable. For example, Instruction with multiple definitions can
+ // result in this condition.
+ if (isNewRegClobberedByRefs(RegRefBegin, RegRefEnd, NewReg)) continue;
// If NewReg is dead and NewReg's most recent def is not before
// AntiDepReg's kill, it's safe to replace AntiDepReg with NewReg.
assert(((KillIndices[AntiDepReg] == ~0u) != (DefIndices[AntiDepReg] == ~0u))
BreakAntiDependencies(const std::vector<SUnit>& SUnits,
MachineBasicBlock::iterator Begin,
MachineBasicBlock::iterator End,
- unsigned InsertPosIndex) {
+ unsigned InsertPosIndex,
+ DbgValueVector &DbgValues) {
// The code below assumes that there is at least one instruction,
// so just duck out immediately if the block is empty.
if (SUnits.empty()) return 0;
if (Edge->getKind() == SDep::Anti) {
AntiDepReg = Edge->getReg();
assert(AntiDepReg != 0 && "Anti-dependence on reg0?");
- if (!AllocatableSet.test(AntiDepReg))
+ if (!RegClassInfo.isAllocatable(AntiDepReg))
// Don't break anti-dependencies on non-allocatable registers.
AntiDepReg = 0;
else if (KeepRegs.count(AntiDepReg))
// TODO: Instead of picking the first free register, consider which might
// be the best.
if (AntiDepReg != 0) {
- if (unsigned NewReg = findSuitableFreeRegister(MI, AntiDepReg,
+ std::pair<std::multimap<unsigned, MachineOperand *>::iterator,
+ std::multimap<unsigned, MachineOperand *>::iterator>
+ Range = RegRefs.equal_range(AntiDepReg);
+ if (unsigned NewReg = findSuitableFreeRegister(Range.first, Range.second,
+ AntiDepReg,
LastNewReg[AntiDepReg],
RC)) {
DEBUG(dbgs() << "Breaking anti-dependence edge on "
// Update the references to the old register to refer to the new
// register.
- std::pair<std::multimap<unsigned, MachineOperand *>::iterator,
- std::multimap<unsigned, MachineOperand *>::iterator>
- Range = RegRefs.equal_range(AntiDepReg);
for (std::multimap<unsigned, MachineOperand *>::iterator
Q = Range.first, QE = Range.second; Q != QE; ++Q) {
Q->second->setReg(NewReg);
// as well.
const SUnit *SU = MISUnitMap[Q->second->getParent()];
if (!SU) continue;
- for (unsigned i = 0, e = SU->DbgInstrList.size() ; i < e ; ++i) {
- MachineInstr *DI = SU->DbgInstrList[i];
- assert (DI->getNumOperands()==3 && DI->getOperand(0).isReg() &&
- DI->getOperand(0).getReg()
- && "Non register dbg_value attached to SUnit!");
- if (DI->getOperand(0).getReg() == AntiDepReg)
- DI->getOperand(0).setReg(NewReg);
- }
+ for (DbgValueVector::iterator DVI = DbgValues.begin(),
+ DVE = DbgValues.end(); DVI != DVE; ++DVI)
+ if (DVI->second == Q->second->getParent())
+ UpdateDbgValue(DVI->first, AntiDepReg, NewReg);
}
// We just went back in time and modified history; the
- // liveness information for the anti-depenence reg is now
+ // liveness information for the anti-dependence reg is now
// inconsistent. Set the state as if it were dead.
Classes[NewReg] = Classes[AntiDepReg];
DefIndices[NewReg] = DefIndices[AntiDepReg];
projects / oota-llvm.git / blobdiff