//
//===----------------------------------------------------------------------===//
-#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;
decreaseSetPressure(MaxSetPressure, RC, TRI);
}
+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';
+ }
+}
+
/// 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;
}
/// 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.
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) {
+/// 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];
PSetID = i;
}
}
- return ExcessUnits;
+ Delta.Excess.PSetID = PSetID;
+ Delta.Excess.UnitIncrease = 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.
+/// Find the max change in max pressure that either surpasses a critical PSet
+/// limit or exceeds the current MaxPressureLimit.
///
-/// This assumes that the current LiveOut set is sufficient.
+/// 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.
///
-/// 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) {
+/// 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, 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);
// 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)
- && (findRegAlias(Reg, PhysRegOpers.Defs, TRI)
- == PhysRegOpers.Defs.end())) {
+ 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)
- && (std::find(VirtRegOpers.Defs.begin(), VirtRegOpers.Defs.end(), Reg)
- != VirtRegOpers.Defs.end())) {
+ 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");
+}
+
+/// 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);
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.
+/// 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 assumes that the current LiveIn set is sufficient.
-void RegPressureTracker::
-getMaxDownwardPressureDelta(const MachineInstr *MI, RegPressureDelta &Delta) {
+/// 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, 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);
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);
+/// 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);
+}
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