for (const int *PSet = TRI->getRegClassPressureSets(RC);
*PSet != -1; ++PSet) {
CurrSetPressure[*PSet] += Weight;
- if (CurrSetPressure[*PSet] > MaxSetPressure[*PSet])
+ if (&CurrSetPressure != &MaxSetPressure
+ && CurrSetPressure[*PSet] > MaxSetPressure[*PSet]) {
MaxSetPressure[*PSet] = CurrSetPressure[*PSet];
+ }
}
}
}
}
+/// Force liveness of registers.
+void RegPressureTracker::addLiveRegs(ArrayRef<unsigned> Regs) {
+ for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
+ if (TargetRegisterInfo::isVirtualRegister(Regs[i])) {
+ if (LiveVirtRegs.insert(Regs[i]).second)
+ increaseVirtRegPressure(Regs[i]);
+ }
+ else {
+ if (!hasRegAlias(Regs[i], LivePhysRegs, TRI)) {
+ LivePhysRegs.insert(Regs[i]);
+ increasePhysRegPressure(Regs[i]);
+ }
+ }
+ }
+}
+
/// Add PhysReg to the live in set and increase max pressure.
void RegPressureTracker::discoverPhysLiveIn(unsigned Reg) {
assert(!LivePhysRegs.count(Reg) && "avoid bumping max pressure twice");
// Kill liveness at live defs.
// TODO: consider earlyclobbers?
- for (unsigned i = 0; i < PhysRegOpers.Defs.size(); ++i) {
+ for (unsigned i = 0, e = PhysRegOpers.Defs.size(); i < e; ++i) {
unsigned Reg = PhysRegOpers.Defs[i];
if (LivePhysRegs.erase(Reg))
decreasePhysRegPressure(Reg);
else
discoverPhysLiveOut(Reg);
}
- for (unsigned i = 0; i < VirtRegOpers.Defs.size(); ++i) {
+ for (unsigned i = 0, e = VirtRegOpers.Defs.size(); i < e; ++i) {
unsigned Reg = VirtRegOpers.Defs[i];
if (LiveVirtRegs.erase(Reg))
decreaseVirtRegPressure(Reg);
}
// Generate liveness for uses.
- for (unsigned i = 0; i < PhysRegOpers.Uses.size(); ++i) {
+ for (unsigned i = 0, e = PhysRegOpers.Uses.size(); i < e; ++i) {
unsigned Reg = PhysRegOpers.Uses[i];
if (!hasRegAlias(Reg, LivePhysRegs, TRI)) {
increasePhysRegPressure(Reg);
LivePhysRegs.insert(Reg);
}
}
- for (unsigned i = 0; i < VirtRegOpers.Uses.size(); ++i) {
+ for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
unsigned Reg = VirtRegOpers.Uses[i];
if (!LiveVirtRegs.count(Reg)) {
// Adjust liveouts if LiveIntervals are available.
collectOperands(CurrPos, PhysRegOpers, VirtRegOpers, TRI, RCI);
// Kill liveness at last uses.
- for (unsigned i = 0; i < PhysRegOpers.Uses.size(); ++i) {
+ for (unsigned i = 0, e = PhysRegOpers.Uses.size(); i < e; ++i) {
unsigned Reg = PhysRegOpers.Uses[i];
if (!hasRegAlias(Reg, LivePhysRegs, TRI))
discoverPhysLiveIn(Reg);
LivePhysRegs.erase(Reg);
}
}
- for (unsigned i = 0; i < VirtRegOpers.Uses.size(); ++i) {
+ for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
unsigned Reg = VirtRegOpers.Uses[i];
if (RequireIntervals) {
const LiveInterval *LI = &LIS->getInterval(Reg);
}
// Generate liveness for defs.
- for (unsigned i = 0; i < PhysRegOpers.Defs.size(); ++i) {
+ for (unsigned i = 0, e = PhysRegOpers.Defs.size(); i < e; ++i) {
unsigned Reg = PhysRegOpers.Defs[i];
if (!hasRegAlias(Reg, LivePhysRegs, TRI)) {
increasePhysRegPressure(Reg);
LivePhysRegs.insert(Reg);
}
}
- for (unsigned i = 0; i < VirtRegOpers.Defs.size(); ++i) {
+ for (unsigned i = 0, e = VirtRegOpers.Defs.size(); i < e; ++i) {
unsigned Reg = VirtRegOpers.Defs[i];
if (LiveVirtRegs.insert(Reg).second)
increaseVirtRegPressure(Reg);
while (CurrPos != MBB->end() && CurrPos->isDebugValue());
return true;
}
+
+// Find the max change in excess pressure across all sets.
+static int computeMaxPressureDelta(ArrayRef<unsigned> OldPressureVec,
+ ArrayRef<unsigned> NewPressureVec,
+ unsigned &PSetID,
+ const TargetRegisterInfo *TRI) {
+ int ExcessUnits = 0;
+ for (unsigned i = 0, e = OldPressureVec.size(); i < e; ++i) {
+ unsigned POld = OldPressureVec[i];
+ unsigned PNew = NewPressureVec[i];
+ int PDiff = (int)PNew - (int)POld;
+ if (!PDiff) // No change in this set in the common case.
+ continue;
+ // Only consider change beyond the limit.
+ unsigned Limit = TRI->getRegPressureSetLimit(i);
+ if (Limit > POld) {
+ if (Limit > PNew)
+ PDiff = 0; // Under the limit
+ else
+ PDiff = PNew - Limit; // Just exceeded limit.
+ }
+ else if (Limit > PNew)
+ PDiff = Limit - POld; // Just obeyed limit.
+
+ if (std::abs(PDiff) > std::abs(ExcessUnits)) {
+ ExcessUnits = PDiff;
+ PSetID = i;
+ }
+ }
+ return ExcessUnits;
+}
+
+/// Consider the pressure increase caused by traversing this instruction
+/// bottom-up. Find the pressure set with the most change beyond its pressure
+/// limit based on the tracker's current pressure, and return the change in
+/// number of register units of that pressure set introduced by this
+/// instruction.
+///
+/// This assumes that the current LiveOut set is sufficient.
+///
+/// FIXME: This is expensive for an on-the-fly query. We need to cache the
+/// result per-SUnit with enough information to adjust for the current
+/// scheduling position. But this works as a proof of concept.
+void RegPressureTracker::
+getMaxUpwardPressureDelta(const MachineInstr *MI, RegPressureDelta &Delta) {
+ // Account for register pressure similar to RegPressureTracker::recede().
+ PhysRegOperands PhysRegOpers;
+ VirtRegOperands VirtRegOpers;
+ collectOperands(MI, PhysRegOpers, VirtRegOpers, TRI, RCI);
+
+ // Snapshot Pressure.
+ std::vector<unsigned> SavedPressure = CurrSetPressure;
+ std::vector<unsigned> SavedMaxPressure = P.MaxSetPressure;
+
+ // Boost max pressure for all dead defs together.
+ // Since CurrSetPressure and MaxSetPressure
+ increasePhysRegPressure(PhysRegOpers.DeadDefs);
+ increaseVirtRegPressure(VirtRegOpers.DeadDefs);
+ decreasePhysRegPressure(PhysRegOpers.DeadDefs);
+ decreaseVirtRegPressure(VirtRegOpers.DeadDefs);
+
+ // Kill liveness at live defs.
+ decreasePhysRegPressure(PhysRegOpers.Defs);
+ decreaseVirtRegPressure(VirtRegOpers.Defs);
+
+ // Generate liveness for uses.
+ for (unsigned i = 0, e = PhysRegOpers.Uses.size(); i < e; ++i) {
+ unsigned Reg = PhysRegOpers.Uses[i];
+ if (!hasRegAlias(Reg, LivePhysRegs, TRI)) {
+ increasePhysRegPressure(Reg);
+ }
+ }
+ for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
+ unsigned Reg = VirtRegOpers.Uses[i];
+ if (!LiveVirtRegs.count(Reg)) {
+ increaseVirtRegPressure(Reg);
+ }
+ }
+ Delta.ExcessUnits =
+ computeMaxPressureDelta(SavedPressure, CurrSetPressure,
+ Delta.ExcessSetID, TRI);
+ Delta.MaxUnitIncrease =
+ computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure,
+ Delta.MaxSetID, TRI);
+ assert(Delta.MaxUnitIncrease >= 0 && "cannot increase max pressure");
+
+ // Restore the tracker's state.
+ P.MaxSetPressure.swap(SavedMaxPressure);
+ CurrSetPressure.swap(SavedPressure);
+}
+
+/// Helper to find a vreg use between two indices [PriorUseIdx, NextUseIdx).
+static bool findUseBetween(unsigned Reg,
+ SlotIndex PriorUseIdx, SlotIndex NextUseIdx,
+ const MachineRegisterInfo *MRI,
+ const LiveIntervals *LIS) {
+ for (MachineRegisterInfo::use_nodbg_iterator
+ UI = MRI->use_nodbg_begin(Reg), UE = MRI->use_nodbg_end();
+ UI != UE; UI.skipInstruction()) {
+ const MachineInstr* MI = &*UI;
+ SlotIndex InstSlot = LIS->getInstructionIndex(MI).getRegSlot();
+ if (InstSlot >= PriorUseIdx && InstSlot < NextUseIdx)
+ return true;
+ }
+ return false;
+}
+
+/// Consider the pressure increase caused by traversing this instruction
+/// top-down. Find the register class with the most change in its pressure limit
+/// based on the tracker's current pressure, and return the number of excess
+/// register units of that pressure set introduced by this instruction.
+///
+/// This assumes that the current LiveIn set is sufficient.
+void RegPressureTracker::
+getMaxDownwardPressureDelta(const MachineInstr *MI, RegPressureDelta &Delta) {
+ // Account for register pressure similar to RegPressureTracker::recede().
+ PhysRegOperands PhysRegOpers;
+ VirtRegOperands VirtRegOpers;
+ collectOperands(MI, PhysRegOpers, VirtRegOpers, TRI, RCI);
+
+ // Snapshot Pressure.
+ std::vector<unsigned> SavedPressure = CurrSetPressure;
+ std::vector<unsigned> SavedMaxPressure = P.MaxSetPressure;
+
+ // Kill liveness at last uses. Assume allocatable physregs are single-use
+ // rather than checking LiveIntervals.
+ decreasePhysRegPressure(PhysRegOpers.Uses);
+ if (RequireIntervals) {
+ SlotIndex SlotIdx = LIS->getInstructionIndex(MI).getRegSlot();
+ for (unsigned i = 0, e = VirtRegOpers.Uses.size(); i < e; ++i) {
+ unsigned Reg = VirtRegOpers.Uses[i];
+ const LiveInterval *LI = &LIS->getInterval(Reg);
+ // FIXME: allow the caller to pass in the list of vreg uses that remain to
+ // be top-scheduled to avoid searching uses at each query.
+ SlotIndex CurrIdx = LIS->getInstructionIndex(CurrPos).getRegSlot();
+ if (LI->killedAt(SlotIdx)
+ && !findUseBetween(Reg, CurrIdx, SlotIdx, MRI, LIS)) {
+ decreaseVirtRegPressure(Reg);
+ }
+ }
+ }
+
+ // Generate liveness for defs.
+ increasePhysRegPressure(PhysRegOpers.Defs);
+ increaseVirtRegPressure(VirtRegOpers.Defs);
+
+ // Boost pressure for all dead defs together.
+ increasePhysRegPressure(PhysRegOpers.DeadDefs);
+ increaseVirtRegPressure(VirtRegOpers.DeadDefs);
+ decreasePhysRegPressure(PhysRegOpers.DeadDefs);
+ decreaseVirtRegPressure(VirtRegOpers.DeadDefs);
+
+ Delta.ExcessUnits =
+ computeMaxPressureDelta(SavedPressure, CurrSetPressure,
+ Delta.ExcessSetID, TRI);
+ Delta.MaxUnitIncrease =
+ computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure,
+ Delta.MaxSetID, TRI);
+
+ // Restore the tracker's state.
+ P.MaxSetPressure.swap(SavedMaxPressure);
+ CurrSetPressure.swap(SavedPressure);
+}
projects / oota-llvm.git / blobdiff