MRI(MF.getRegInfo()),
TII(MF.getTarget().getInstrInfo()),
TRI(MF.getTarget().getRegisterInfo()),
- AllocatableSet(TRI->getAllocatableSet(MF))
-{
-}
+ AllocatableSet(TRI->getAllocatableSet(MF)),
+ Classes(TRI->getNumRegs(), static_cast<const TargetRegisterClass *>(0)),
+ KillIndices(TRI->getNumRegs(), 0),
+ DefIndices(TRI->getNumRegs(), 0) {}
CriticalAntiDepBreaker::~CriticalAntiDepBreaker() {
}
void CriticalAntiDepBreaker::StartBlock(MachineBasicBlock *BB) {
- // Clear out the register class data.
- std::fill(Classes, array_endof(Classes),
- static_cast<const TargetRegisterClass *>(0));
-
- // Initialize the indices to indicate that no registers are live.
const unsigned BBSize = BB->size();
- for (unsigned i = 0; i < TRI->getNumRegs(); ++i) {
+ for (unsigned i = 0, e = TRI->getNumRegs(); i != e; ++i) {
+ // Clear out the register class data.
+ Classes[i] = static_cast<const TargetRegisterClass *>(0);
+
+ // Initialize the indices to indicate that no registers are live.
KillIndices[i] = ~0u;
DefIndices[i] = BBSize;
}
Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
KillIndices[Reg] = BB->size();
DefIndices[Reg] = ~0u;
+
// Repeat, for all aliases.
for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
unsigned AliasReg = *Alias;
Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
KillIndices[Reg] = BB->size();
DefIndices[Reg] = ~0u;
+
// Repeat, for all aliases.
for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
unsigned AliasReg = *Alias;
Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
KillIndices[Reg] = BB->size();
DefIndices[Reg] = ~0u;
+
// Repeat, for all aliases.
for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
unsigned AliasReg = *Alias;
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]
// ...
}
}
+// Check all machine instructions that define the antidependent register.
+// Return true if any of these instructions define the new register.
+bool
+CriticalAntiDepBreaker::isNewRegModifiedByRefs(RegRefIter RegRefBegin,
+ RegRefIter RegRefEnd,
+ unsigned NewReg)
+{
+ for (RegRefIter I = RegRefBegin; I != RegRefEnd; ++I ) {
+ MachineOperand *MO = I->second;
+ if (MO->isDef()) continue;
+ if (MO->getParent()->modifiesRegister(NewReg, TRI))
+ 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;
// 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 (isNewRegModifiedByRefs(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))
// fix that remaining critical edge too. This is a little more involved,
// because unlike the most recent register, less recent registers should
// still be considered, though only if no other registers are available.
- unsigned LastNewReg[TargetRegisterInfo::FirstVirtualRegister] = {};
+ std::vector<unsigned> LastNewReg(TRI->getNumRegs(), 0);
// Attempt to break anti-dependence edges on the critical path. Walk the
// instructions from the bottom up, tracking information about liveness
// 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);
}
// 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