//
//===----------------------------------------------------------------------===//
-#include "RegisterClassInfo.h"
-#include "RegisterPressure.h"
#include "llvm/CodeGen/LiveInterval.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RegisterClassInfo.h"
+#include "llvm/CodeGen/RegisterPressure.h"
#include "llvm/Target/TargetMachine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
using namespace llvm;
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];
+ }
}
}
decreaseSetPressure(MaxSetPressure, RC, TRI);
}
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+void RegisterPressure::dump(const TargetRegisterInfo *TRI) {
+ dbgs() << "Live In: ";
+ for (unsigned i = 0, e = LiveInRegs.size(); i < e; ++i)
+ dbgs() << PrintReg(LiveInRegs[i], TRI) << " ";
+ dbgs() << '\n';
+ dbgs() << "Live Out: ";
+ for (unsigned i = 0, e = LiveOutRegs.size(); i < e; ++i)
+ dbgs() << PrintReg(LiveOutRegs[i], TRI) << " ";
+ dbgs() << '\n';
+ for (unsigned i = 0, e = MaxSetPressure.size(); i < e; ++i) {
+ if (MaxSetPressure[i] != 0)
+ dbgs() << TRI->getRegPressureSetName(i) << "=" << MaxSetPressure[i]
+ << '\n';
+ }
+}
+#endif
+
/// Increase the current pressure as impacted by these physical registers and
/// bump the high water mark if needed.
void RegPressureTracker::increasePhysRegPressure(ArrayRef<unsigned> Regs) {
static bool hasRegAlias(unsigned Reg, SparseSet<unsigned> &Regs,
const TargetRegisterInfo *TRI) {
assert(!TargetRegisterInfo::isVirtualRegister(Reg) && "only for physregs");
- for (const uint16_t *Alias = TRI->getOverlaps(Reg); *Alias; ++Alias) {
- if (Regs.count(*Alias))
+ for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
+ if (Regs.count(*AI))
return true;
- }
return false;
}
static SmallVectorImpl<unsigned>::iterator
findRegAlias(unsigned Reg, SmallVectorImpl<unsigned> &Regs,
const TargetRegisterInfo *TRI) {
- for (const uint16_t *Alias = TRI->getOverlaps(Reg); *Alias; ++Alias) {
+ for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
SmallVectorImpl<unsigned>::iterator I =
- std::find(Regs.begin(), Regs.end(), *Alias);
+ std::find(Regs.begin(), Regs.end(), *AI);
if (I != Regs.end())
return I;
}
PhysRegOperands &PhysRegOpers,
VirtRegOperands &VirtRegOpers,
const TargetRegisterInfo *TRI,
- const RegisterClassInfo *RCI) {
+ const MachineRegisterInfo *MRI) {
for(ConstMIBundleOperands OperI(MI); OperI.isValid(); ++OperI) {
const MachineOperand &MO = *OperI;
if (!MO.isReg() || !MO.getReg())
if (TargetRegisterInfo::isVirtualRegister(MO.getReg()))
VirtRegOpers.collect(MO, TRI);
- else if (RCI->isAllocatable(MO.getReg()))
+ else if (MRI->isAllocatable(MO.getReg()))
PhysRegOpers.collect(MO, TRI);
}
// Remove redundant physreg dead defs.
}
}
+/// 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");
- if (findRegAlias(Reg, P.LiveInRegs, TRI) == P.LiveInRegs.end())
+ if (findRegAlias(Reg, P.LiveInRegs, TRI) != P.LiveInRegs.end())
return;
// At live in discovery, unconditionally increase the high water mark.
/// Add PhysReg to the live out set and increase max pressure.
void RegPressureTracker::discoverPhysLiveOut(unsigned Reg) {
assert(!LivePhysRegs.count(Reg) && "avoid bumping max pressure twice");
- if (findRegAlias(Reg, P.LiveOutRegs, TRI) == P.LiveOutRegs.end())
+ if (findRegAlias(Reg, P.LiveOutRegs, TRI) != P.LiveOutRegs.end())
return;
// At live out discovery, unconditionally increase the high water mark.
PhysRegOperands PhysRegOpers;
VirtRegOperands VirtRegOpers;
- collectOperands(CurrPos, PhysRegOpers, VirtRegOpers, TRI, RCI);
+ collectOperands(CurrPos, PhysRegOpers, VirtRegOpers, TRI, MRI);
// Boost pressure for all dead defs together.
increasePhysRegPressure(PhysRegOpers.DeadDefs);
PhysRegOperands PhysRegOpers;
VirtRegOperands VirtRegOpers;
- collectOperands(CurrPos, PhysRegOpers, VirtRegOpers, TRI, RCI);
+ collectOperands(CurrPos, PhysRegOpers, VirtRegOpers, TRI, MRI);
// Kill liveness at last uses.
for (unsigned i = 0, e = PhysRegOpers.Uses.size(); i < e; ++i) {
while (CurrPos != MBB->end() && CurrPos->isDebugValue());
return true;
}
+
+/// Find the max change in excess pressure across all sets.
+static void computeExcessPressureDelta(ArrayRef<unsigned> OldPressureVec,
+ ArrayRef<unsigned> NewPressureVec,
+ RegPressureDelta &Delta,
+ const TargetRegisterInfo *TRI) {
+ int ExcessUnits = 0;
+ unsigned PSetID = ~0U;
+ 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;
+ }
+ }
+ Delta.Excess.PSetID = PSetID;
+ Delta.Excess.UnitIncrease = ExcessUnits;
+}
+
+/// Find the max change in max pressure that either surpasses a critical PSet
+/// limit or exceeds the current MaxPressureLimit.
+///
+/// FIXME: comparing each element of the old and new MaxPressure vectors here is
+/// silly. It's done now to demonstrate the concept but will go away with a
+/// RegPressureTracker API change to work with pressure differences.
+static void computeMaxPressureDelta(ArrayRef<unsigned> OldMaxPressureVec,
+ ArrayRef<unsigned> NewMaxPressureVec,
+ ArrayRef<PressureElement> CriticalPSets,
+ ArrayRef<unsigned> MaxPressureLimit,
+ RegPressureDelta &Delta) {
+ Delta.CriticalMax = PressureElement();
+ Delta.CurrentMax = PressureElement();
+
+ unsigned CritIdx = 0, CritEnd = CriticalPSets.size();
+ for (unsigned i = 0, e = OldMaxPressureVec.size(); i < e; ++i) {
+ unsigned POld = OldMaxPressureVec[i];
+ unsigned PNew = NewMaxPressureVec[i];
+ if (PNew == POld) // No change in this set in the common case.
+ continue;
+
+ while (CritIdx != CritEnd && CriticalPSets[CritIdx].PSetID < i)
+ ++CritIdx;
+
+ if (CritIdx != CritEnd && CriticalPSets[CritIdx].PSetID == i) {
+ int PDiff = (int)PNew - (int)CriticalPSets[CritIdx].UnitIncrease;
+ if (PDiff > Delta.CriticalMax.UnitIncrease) {
+ Delta.CriticalMax.PSetID = i;
+ Delta.CriticalMax.UnitIncrease = PDiff;
+ }
+ }
+
+ // Find the greatest increase above MaxPressureLimit.
+ // (Ignores negative MDiff).
+ int MDiff = (int)PNew - (int)MaxPressureLimit[i];
+ if (MDiff > Delta.CurrentMax.UnitIncrease) {
+ Delta.CurrentMax.PSetID = i;
+ Delta.CurrentMax.UnitIncrease = PNew;
+ }
+ }
+}
+
+/// Record the upward impact of a single instruction on current register
+/// pressure. Unlike the advance/recede pressure tracking interface, this does
+/// not discover live in/outs.
+///
+/// This is intended for speculative queries. It leaves pressure inconsistent
+/// with the current position, so must be restored by the caller.
+void RegPressureTracker::bumpUpwardPressure(const MachineInstr *MI) {
+ // Account for register pressure similar to RegPressureTracker::recede().
+ PhysRegOperands PhysRegOpers;
+ VirtRegOperands VirtRegOpers;
+ collectOperands(MI, PhysRegOpers, VirtRegOpers, TRI, MRI);
+
+ // 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);
+ }
+}
+
+/// 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,
+ ArrayRef<PressureElement> CriticalPSets,
+ ArrayRef<unsigned> MaxPressureLimit) {
+ // Snapshot Pressure.
+ // FIXME: The snapshot heap space should persist. But I'm planning to
+ // summarize the pressure effect so we don't need to snapshot at all.
+ std::vector<unsigned> SavedPressure = CurrSetPressure;
+ std::vector<unsigned> SavedMaxPressure = P.MaxSetPressure;
+
+ bumpUpwardPressure(MI);
+
+ computeExcessPressureDelta(SavedPressure, CurrSetPressure, Delta, TRI);
+ computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure, CriticalPSets,
+ MaxPressureLimit, Delta);
+ assert(Delta.CriticalMax.UnitIncrease >= 0 &&
+ Delta.CurrentMax.UnitIncrease >= 0 && "cannot decrease 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;
+}
+
+/// Record the downward impact of a single instruction on current register
+/// pressure. Unlike the advance/recede pressure tracking interface, this does
+/// not discover live in/outs.
+///
+/// This is intended for speculative queries. It leaves pressure inconsistent
+/// with the current position, so must be restored by the caller.
+void RegPressureTracker::bumpDownwardPressure(const MachineInstr *MI) {
+ // Account for register pressure similar to RegPressureTracker::recede().
+ PhysRegOperands PhysRegOpers;
+ VirtRegOperands VirtRegOpers;
+ collectOperands(MI, PhysRegOpers, VirtRegOpers, TRI, MRI);
+
+ // 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 bottom-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);
+}
+
+/// 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,
+ ArrayRef<PressureElement> CriticalPSets,
+ ArrayRef<unsigned> MaxPressureLimit) {
+ // Snapshot Pressure.
+ std::vector<unsigned> SavedPressure = CurrSetPressure;
+ std::vector<unsigned> SavedMaxPressure = P.MaxSetPressure;
+
+ bumpDownwardPressure(MI);
+
+ computeExcessPressureDelta(SavedPressure, CurrSetPressure, Delta, TRI);
+ computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure, CriticalPSets,
+ MaxPressureLimit, Delta);
+ assert(Delta.CriticalMax.UnitIncrease >= 0 &&
+ Delta.CurrentMax.UnitIncrease >= 0 && "cannot decrease max pressure");
+
+ // Restore the tracker's state.
+ P.MaxSetPressure.swap(SavedMaxPressure);
+ CurrSetPressure.swap(SavedPressure);
+}
+
+/// Get the pressure of each PSet after traversing this instruction bottom-up.
+void RegPressureTracker::
+getUpwardPressure(const MachineInstr *MI,
+ std::vector<unsigned> &PressureResult,
+ std::vector<unsigned> &MaxPressureResult) {
+ // Snapshot pressure.
+ PressureResult = CurrSetPressure;
+ MaxPressureResult = P.MaxSetPressure;
+
+ bumpUpwardPressure(MI);
+
+ // Current pressure becomes the result. Restore current pressure.
+ P.MaxSetPressure.swap(MaxPressureResult);
+ CurrSetPressure.swap(PressureResult);
+}
+
+/// Get the pressure of each PSet after traversing this instruction top-down.
+void RegPressureTracker::
+getDownwardPressure(const MachineInstr *MI,
+ std::vector<unsigned> &PressureResult,
+ std::vector<unsigned> &MaxPressureResult) {
+ // Snapshot pressure.
+ PressureResult = CurrSetPressure;
+ MaxPressureResult = P.MaxSetPressure;
+
+ bumpDownwardPressure(MI);
+
+ // Current pressure becomes the result. Restore current pressure.
+ P.MaxSetPressure.swap(MaxPressureResult);
+ CurrSetPressure.swap(PressureResult);
+}