| //===-- RegisterPressure.cpp - Dynamic Register Pressure ------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the RegisterPressure class which can be used to track |
| // MachineInstr level register pressure. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/CodeGen/RegisterPressure.h" |
| #include "llvm/CodeGen/LiveInterval.h" |
| #include "llvm/CodeGen/LiveIntervalAnalysis.h" |
| #include "llvm/CodeGen/MachineRegisterInfo.h" |
| #include "llvm/CodeGen/RegisterClassInfo.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| |
| using namespace llvm; |
| |
| /// Increase pressure for each pressure set provided by TargetRegisterInfo. |
| static void increaseSetPressure(std::vector<unsigned> &CurrSetPressure, |
| PSetIterator PSetI) { |
| unsigned Weight = PSetI.getWeight(); |
| for (; PSetI.isValid(); ++PSetI) |
| CurrSetPressure[*PSetI] += Weight; |
| } |
| |
| /// Decrease pressure for each pressure set provided by TargetRegisterInfo. |
| static void decreaseSetPressure(std::vector<unsigned> &CurrSetPressure, |
| PSetIterator PSetI) { |
| unsigned Weight = PSetI.getWeight(); |
| for (; PSetI.isValid(); ++PSetI) { |
| assert(CurrSetPressure[*PSetI] >= Weight && "register pressure underflow"); |
| CurrSetPressure[*PSetI] -= Weight; |
| } |
| } |
| |
| LLVM_DUMP_METHOD |
| void llvm::dumpRegSetPressure(ArrayRef<unsigned> SetPressure, |
| const TargetRegisterInfo *TRI) { |
| bool Empty = true; |
| for (unsigned i = 0, e = SetPressure.size(); i < e; ++i) { |
| if (SetPressure[i] != 0) { |
| dbgs() << TRI->getRegPressureSetName(i) << "=" << SetPressure[i] << '\n'; |
| Empty = false; |
| } |
| } |
| if (Empty) |
| dbgs() << "\n"; |
| } |
| |
| LLVM_DUMP_METHOD |
| void RegisterPressure::dump(const TargetRegisterInfo *TRI) const { |
| dbgs() << "Max Pressure: "; |
| dumpRegSetPressure(MaxSetPressure, 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'; |
| } |
| |
| LLVM_DUMP_METHOD |
| void RegPressureTracker::dump() const { |
| if (!isTopClosed() || !isBottomClosed()) { |
| dbgs() << "Curr Pressure: "; |
| dumpRegSetPressure(CurrSetPressure, TRI); |
| } |
| P.dump(TRI); |
| } |
| |
| /// Increase the current pressure as impacted by these registers and bump |
| /// the high water mark if needed. |
| void RegPressureTracker::increaseRegPressure(ArrayRef<unsigned> RegUnits) { |
| for (unsigned i = 0, e = RegUnits.size(); i != e; ++i) { |
| PSetIterator PSetI = MRI->getPressureSets(RegUnits[i]); |
| unsigned Weight = PSetI.getWeight(); |
| for (; PSetI.isValid(); ++PSetI) { |
| CurrSetPressure[*PSetI] += Weight; |
| if (CurrSetPressure[*PSetI] > P.MaxSetPressure[*PSetI]) { |
| P.MaxSetPressure[*PSetI] = CurrSetPressure[*PSetI]; |
| } |
| } |
| } |
| } |
| |
| /// Simply decrease the current pressure as impacted by these registers. |
| void RegPressureTracker::decreaseRegPressure(ArrayRef<unsigned> RegUnits) { |
| for (unsigned I = 0, E = RegUnits.size(); I != E; ++I) |
| decreaseSetPressure(CurrSetPressure, MRI->getPressureSets(RegUnits[I])); |
| } |
| |
| /// Clear the result so it can be used for another round of pressure tracking. |
| void IntervalPressure::reset() { |
| TopIdx = BottomIdx = SlotIndex(); |
| MaxSetPressure.clear(); |
| LiveInRegs.clear(); |
| LiveOutRegs.clear(); |
| } |
| |
| /// Clear the result so it can be used for another round of pressure tracking. |
| void RegionPressure::reset() { |
| TopPos = BottomPos = MachineBasicBlock::const_iterator(); |
| MaxSetPressure.clear(); |
| LiveInRegs.clear(); |
| LiveOutRegs.clear(); |
| } |
| |
| /// If the current top is not less than or equal to the next index, open it. |
| /// We happen to need the SlotIndex for the next top for pressure update. |
| void IntervalPressure::openTop(SlotIndex NextTop) { |
| if (TopIdx <= NextTop) |
| return; |
| TopIdx = SlotIndex(); |
| LiveInRegs.clear(); |
| } |
| |
| /// If the current top is the previous instruction (before receding), open it. |
| void RegionPressure::openTop(MachineBasicBlock::const_iterator PrevTop) { |
| if (TopPos != PrevTop) |
| return; |
| TopPos = MachineBasicBlock::const_iterator(); |
| LiveInRegs.clear(); |
| } |
| |
| /// If the current bottom is not greater than the previous index, open it. |
| void IntervalPressure::openBottom(SlotIndex PrevBottom) { |
| if (BottomIdx > PrevBottom) |
| return; |
| BottomIdx = SlotIndex(); |
| LiveInRegs.clear(); |
| } |
| |
| /// If the current bottom is the previous instr (before advancing), open it. |
| void RegionPressure::openBottom(MachineBasicBlock::const_iterator PrevBottom) { |
| if (BottomPos != PrevBottom) |
| return; |
| BottomPos = MachineBasicBlock::const_iterator(); |
| LiveInRegs.clear(); |
| } |
| |
| const LiveRange *RegPressureTracker::getLiveRange(unsigned Reg) const { |
| if (TargetRegisterInfo::isVirtualRegister(Reg)) |
| return &LIS->getInterval(Reg); |
| return LIS->getCachedRegUnit(Reg); |
| } |
| |
| void RegPressureTracker::reset() { |
| MBB = nullptr; |
| LIS = nullptr; |
| |
| CurrSetPressure.clear(); |
| LiveThruPressure.clear(); |
| P.MaxSetPressure.clear(); |
| |
| if (RequireIntervals) |
| static_cast<IntervalPressure&>(P).reset(); |
| else |
| static_cast<RegionPressure&>(P).reset(); |
| |
| LiveRegs.PhysRegs.clear(); |
| LiveRegs.VirtRegs.clear(); |
| UntiedDefs.clear(); |
| } |
| |
| /// Setup the RegPressureTracker. |
| /// |
| /// TODO: Add support for pressure without LiveIntervals. |
| void RegPressureTracker::init(const MachineFunction *mf, |
| const RegisterClassInfo *rci, |
| const LiveIntervals *lis, |
| const MachineBasicBlock *mbb, |
| MachineBasicBlock::const_iterator pos, |
| bool ShouldTrackUntiedDefs) |
| { |
| reset(); |
| |
| MF = mf; |
| TRI = MF->getSubtarget().getRegisterInfo(); |
| RCI = rci; |
| MRI = &MF->getRegInfo(); |
| MBB = mbb; |
| TrackUntiedDefs = ShouldTrackUntiedDefs; |
| |
| if (RequireIntervals) { |
| assert(lis && "IntervalPressure requires LiveIntervals"); |
| LIS = lis; |
| } |
| |
| CurrPos = pos; |
| CurrSetPressure.assign(TRI->getNumRegPressureSets(), 0); |
| |
| P.MaxSetPressure = CurrSetPressure; |
| |
| LiveRegs.PhysRegs.setUniverse(TRI->getNumRegs()); |
| LiveRegs.VirtRegs.setUniverse(MRI->getNumVirtRegs()); |
| if (TrackUntiedDefs) |
| UntiedDefs.setUniverse(MRI->getNumVirtRegs()); |
| } |
| |
| /// Does this pressure result have a valid top position and live ins. |
| bool RegPressureTracker::isTopClosed() const { |
| if (RequireIntervals) |
| return static_cast<IntervalPressure&>(P).TopIdx.isValid(); |
| return (static_cast<RegionPressure&>(P).TopPos == |
| MachineBasicBlock::const_iterator()); |
| } |
| |
| /// Does this pressure result have a valid bottom position and live outs. |
| bool RegPressureTracker::isBottomClosed() const { |
| if (RequireIntervals) |
| return static_cast<IntervalPressure&>(P).BottomIdx.isValid(); |
| return (static_cast<RegionPressure&>(P).BottomPos == |
| MachineBasicBlock::const_iterator()); |
| } |
| |
| |
| SlotIndex RegPressureTracker::getCurrSlot() const { |
| MachineBasicBlock::const_iterator IdxPos = CurrPos; |
| while (IdxPos != MBB->end() && IdxPos->isDebugValue()) |
| ++IdxPos; |
| if (IdxPos == MBB->end()) |
| return LIS->getMBBEndIdx(MBB); |
| return LIS->getInstructionIndex(IdxPos).getRegSlot(); |
| } |
| |
| /// Set the boundary for the top of the region and summarize live ins. |
| void RegPressureTracker::closeTop() { |
| if (RequireIntervals) |
| static_cast<IntervalPressure&>(P).TopIdx = getCurrSlot(); |
| else |
| static_cast<RegionPressure&>(P).TopPos = CurrPos; |
| |
| assert(P.LiveInRegs.empty() && "inconsistent max pressure result"); |
| P.LiveInRegs.reserve(LiveRegs.PhysRegs.size() + LiveRegs.VirtRegs.size()); |
| P.LiveInRegs.append(LiveRegs.PhysRegs.begin(), LiveRegs.PhysRegs.end()); |
| for (SparseSet<unsigned>::const_iterator I = |
| LiveRegs.VirtRegs.begin(), E = LiveRegs.VirtRegs.end(); I != E; ++I) |
| P.LiveInRegs.push_back(*I); |
| std::sort(P.LiveInRegs.begin(), P.LiveInRegs.end()); |
| P.LiveInRegs.erase(std::unique(P.LiveInRegs.begin(), P.LiveInRegs.end()), |
| P.LiveInRegs.end()); |
| } |
| |
| /// Set the boundary for the bottom of the region and summarize live outs. |
| void RegPressureTracker::closeBottom() { |
| if (RequireIntervals) |
| static_cast<IntervalPressure&>(P).BottomIdx = getCurrSlot(); |
| else |
| static_cast<RegionPressure&>(P).BottomPos = CurrPos; |
| |
| assert(P.LiveOutRegs.empty() && "inconsistent max pressure result"); |
| P.LiveOutRegs.reserve(LiveRegs.PhysRegs.size() + LiveRegs.VirtRegs.size()); |
| P.LiveOutRegs.append(LiveRegs.PhysRegs.begin(), LiveRegs.PhysRegs.end()); |
| for (SparseSet<unsigned>::const_iterator I = |
| LiveRegs.VirtRegs.begin(), E = LiveRegs.VirtRegs.end(); I != E; ++I) |
| P.LiveOutRegs.push_back(*I); |
| std::sort(P.LiveOutRegs.begin(), P.LiveOutRegs.end()); |
| P.LiveOutRegs.erase(std::unique(P.LiveOutRegs.begin(), P.LiveOutRegs.end()), |
| P.LiveOutRegs.end()); |
| } |
| |
| /// Finalize the region boundaries and record live ins and live outs. |
| void RegPressureTracker::closeRegion() { |
| if (!isTopClosed() && !isBottomClosed()) { |
| assert(LiveRegs.PhysRegs.empty() && LiveRegs.VirtRegs.empty() && |
| "no region boundary"); |
| return; |
| } |
| if (!isBottomClosed()) |
| closeBottom(); |
| else if (!isTopClosed()) |
| closeTop(); |
| // If both top and bottom are closed, do nothing. |
| } |
| |
| /// The register tracker is unaware of global liveness so ignores normal |
| /// live-thru ranges. However, two-address or coalesced chains can also lead |
| /// to live ranges with no holes. Count these to inform heuristics that we |
| /// can never drop below this pressure. |
| void RegPressureTracker::initLiveThru(const RegPressureTracker &RPTracker) { |
| LiveThruPressure.assign(TRI->getNumRegPressureSets(), 0); |
| assert(isBottomClosed() && "need bottom-up tracking to intialize."); |
| for (unsigned i = 0, e = P.LiveOutRegs.size(); i < e; ++i) { |
| unsigned Reg = P.LiveOutRegs[i]; |
| if (TargetRegisterInfo::isVirtualRegister(Reg) |
| && !RPTracker.hasUntiedDef(Reg)) { |
| increaseSetPressure(LiveThruPressure, MRI->getPressureSets(Reg)); |
| } |
| } |
| } |
| |
| /// \brief Convenient wrapper for checking membership in RegisterOperands. |
| /// (std::count() doesn't have an early exit). |
| static bool containsReg(ArrayRef<unsigned> RegUnits, unsigned RegUnit) { |
| return std::find(RegUnits.begin(), RegUnits.end(), RegUnit) != RegUnits.end(); |
| } |
| |
| /// Collect this instruction's unique uses and defs into SmallVectors for |
| /// processing defs and uses in order. |
| /// |
| /// FIXME: always ignore tied opers |
| class RegisterOperands { |
| const TargetRegisterInfo *TRI; |
| const MachineRegisterInfo *MRI; |
| bool IgnoreDead; |
| |
| public: |
| SmallVector<unsigned, 8> Uses; |
| SmallVector<unsigned, 8> Defs; |
| SmallVector<unsigned, 8> DeadDefs; |
| |
| RegisterOperands(const TargetRegisterInfo *tri, |
| const MachineRegisterInfo *mri, bool ID = false): |
| TRI(tri), MRI(mri), IgnoreDead(ID) {} |
| |
| /// Push this operand's register onto the correct vector. |
| void collect(const MachineOperand &MO) { |
| if (!MO.isReg() || !MO.getReg()) |
| return; |
| if (MO.readsReg()) |
| pushRegUnits(MO.getReg(), Uses); |
| if (MO.isDef()) { |
| if (MO.isDead()) { |
| if (!IgnoreDead) |
| pushRegUnits(MO.getReg(), DeadDefs); |
| } |
| else |
| pushRegUnits(MO.getReg(), Defs); |
| } |
| } |
| |
| protected: |
| void pushRegUnits(unsigned Reg, SmallVectorImpl<unsigned> &RegUnits) { |
| if (TargetRegisterInfo::isVirtualRegister(Reg)) { |
| if (containsReg(RegUnits, Reg)) |
| return; |
| RegUnits.push_back(Reg); |
| } |
| else if (MRI->isAllocatable(Reg)) { |
| for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units) { |
| if (containsReg(RegUnits, *Units)) |
| continue; |
| RegUnits.push_back(*Units); |
| } |
| } |
| } |
| }; |
| |
| /// Collect physical and virtual register operands. |
| static void collectOperands(const MachineInstr *MI, |
| RegisterOperands &RegOpers) { |
| for (ConstMIBundleOperands OperI(MI); OperI.isValid(); ++OperI) |
| RegOpers.collect(*OperI); |
| |
| // Remove redundant physreg dead defs. |
| SmallVectorImpl<unsigned>::iterator I = |
| std::remove_if(RegOpers.DeadDefs.begin(), RegOpers.DeadDefs.end(), |
| std::bind1st(std::ptr_fun(containsReg), RegOpers.Defs)); |
| RegOpers.DeadDefs.erase(I, RegOpers.DeadDefs.end()); |
| } |
| |
| /// Initialize an array of N PressureDiffs. |
| void PressureDiffs::init(unsigned N) { |
| Size = N; |
| if (N <= Max) { |
| memset(PDiffArray, 0, N * sizeof(PressureDiff)); |
| return; |
| } |
| Max = Size; |
| free(PDiffArray); |
| PDiffArray = reinterpret_cast<PressureDiff*>(calloc(N, sizeof(PressureDiff))); |
| } |
| |
| /// Add a change in pressure to the pressure diff of a given instruction. |
| void PressureDiff::addPressureChange(unsigned RegUnit, bool IsDec, |
| const MachineRegisterInfo *MRI) { |
| PSetIterator PSetI = MRI->getPressureSets(RegUnit); |
| int Weight = IsDec ? -PSetI.getWeight() : PSetI.getWeight(); |
| for (; PSetI.isValid(); ++PSetI) { |
| // Find an existing entry in the pressure diff for this PSet. |
| PressureDiff::iterator I = begin(), E = end(); |
| for (; I != E && I->isValid(); ++I) { |
| if (I->getPSet() >= *PSetI) |
| break; |
| } |
| // If all pressure sets are more constrained, skip the remaining PSets. |
| if (I == E) |
| break; |
| // Insert this PressureChange. |
| if (!I->isValid() || I->getPSet() != *PSetI) { |
| PressureChange PTmp = PressureChange(*PSetI); |
| for (PressureDiff::iterator J = I; J != E && PTmp.isValid(); ++J) |
| std::swap(*J,PTmp); |
| } |
| // Update the units for this pressure set. |
| I->setUnitInc(I->getUnitInc() + Weight); |
| } |
| } |
| |
| /// Record the pressure difference induced by the given operand list. |
| static void collectPDiff(PressureDiff &PDiff, RegisterOperands &RegOpers, |
| const MachineRegisterInfo *MRI) { |
| assert(!PDiff.begin()->isValid() && "stale PDiff"); |
| |
| for (unsigned i = 0, e = RegOpers.Defs.size(); i != e; ++i) |
| PDiff.addPressureChange(RegOpers.Defs[i], true, MRI); |
| |
| for (unsigned i = 0, e = RegOpers.Uses.size(); i != e; ++i) |
| PDiff.addPressureChange(RegOpers.Uses[i], false, MRI); |
| } |
| |
| /// Force liveness of registers. |
| void RegPressureTracker::addLiveRegs(ArrayRef<unsigned> Regs) { |
| for (unsigned i = 0, e = Regs.size(); i != e; ++i) { |
| if (LiveRegs.insert(Regs[i])) |
| increaseRegPressure(Regs[i]); |
| } |
| } |
| |
| /// Add Reg to the live in set and increase max pressure. |
| void RegPressureTracker::discoverLiveIn(unsigned Reg) { |
| assert(!LiveRegs.contains(Reg) && "avoid bumping max pressure twice"); |
| if (containsReg(P.LiveInRegs, Reg)) |
| return; |
| |
| // At live in discovery, unconditionally increase the high water mark. |
| P.LiveInRegs.push_back(Reg); |
| increaseSetPressure(P.MaxSetPressure, MRI->getPressureSets(Reg)); |
| } |
| |
| /// Add Reg to the live out set and increase max pressure. |
| void RegPressureTracker::discoverLiveOut(unsigned Reg) { |
| assert(!LiveRegs.contains(Reg) && "avoid bumping max pressure twice"); |
| if (containsReg(P.LiveOutRegs, Reg)) |
| return; |
| |
| // At live out discovery, unconditionally increase the high water mark. |
| P.LiveOutRegs.push_back(Reg); |
| increaseSetPressure(P.MaxSetPressure, MRI->getPressureSets(Reg)); |
| } |
| |
| /// Recede across the previous instruction. If LiveUses is provided, record any |
| /// RegUnits that are made live by the current instruction's uses. This includes |
| /// registers that are both defined and used by the instruction. If a pressure |
| /// difference pointer is provided record the changes is pressure caused by this |
| /// instruction independent of liveness. |
| bool RegPressureTracker::recede(SmallVectorImpl<unsigned> *LiveUses, |
| PressureDiff *PDiff) { |
| // Check for the top of the analyzable region. |
| if (CurrPos == MBB->begin()) { |
| closeRegion(); |
| return false; |
| } |
| if (!isBottomClosed()) |
| closeBottom(); |
| |
| // Open the top of the region using block iterators. |
| if (!RequireIntervals && isTopClosed()) |
| static_cast<RegionPressure&>(P).openTop(CurrPos); |
| |
| // Find the previous instruction. |
| do |
| --CurrPos; |
| while (CurrPos != MBB->begin() && CurrPos->isDebugValue()); |
| |
| if (CurrPos->isDebugValue()) { |
| closeRegion(); |
| return false; |
| } |
| SlotIndex SlotIdx; |
| if (RequireIntervals) |
| SlotIdx = LIS->getInstructionIndex(CurrPos).getRegSlot(); |
| |
| // Open the top of the region using slot indexes. |
| if (RequireIntervals && isTopClosed()) |
| static_cast<IntervalPressure&>(P).openTop(SlotIdx); |
| |
| RegisterOperands RegOpers(TRI, MRI); |
| collectOperands(CurrPos, RegOpers); |
| |
| if (PDiff) |
| collectPDiff(*PDiff, RegOpers, MRI); |
| |
| // Boost pressure for all dead defs together. |
| increaseRegPressure(RegOpers.DeadDefs); |
| decreaseRegPressure(RegOpers.DeadDefs); |
| |
| // Kill liveness at live defs. |
| // TODO: consider earlyclobbers? |
| for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) { |
| unsigned Reg = RegOpers.Defs[i]; |
| bool DeadDef = false; |
| if (RequireIntervals) { |
| const LiveRange *LR = getLiveRange(Reg); |
| if (LR) { |
| LiveQueryResult LRQ = LR->Query(SlotIdx); |
| DeadDef = LRQ.isDeadDef(); |
| } |
| } |
| if (DeadDef) { |
| // LiveIntervals knows this is a dead even though it's MachineOperand is |
| // not flagged as such. Since this register will not be recorded as |
| // live-out, increase its PDiff value to avoid underflowing pressure. |
| if (PDiff) |
| PDiff->addPressureChange(Reg, false, MRI); |
| } else { |
| if (LiveRegs.erase(Reg)) |
| decreaseRegPressure(Reg); |
| else |
| discoverLiveOut(Reg); |
| } |
| } |
| |
| // Generate liveness for uses. |
| for (unsigned i = 0, e = RegOpers.Uses.size(); i < e; ++i) { |
| unsigned Reg = RegOpers.Uses[i]; |
| if (!LiveRegs.contains(Reg)) { |
| // Adjust liveouts if LiveIntervals are available. |
| if (RequireIntervals) { |
| const LiveRange *LR = getLiveRange(Reg); |
| if (LR) { |
| LiveQueryResult LRQ = LR->Query(SlotIdx); |
| if (!LRQ.isKill() && !LRQ.valueDefined()) |
| discoverLiveOut(Reg); |
| } |
| } |
| increaseRegPressure(Reg); |
| LiveRegs.insert(Reg); |
| if (LiveUses && !containsReg(*LiveUses, Reg)) |
| LiveUses->push_back(Reg); |
| } |
| } |
| if (TrackUntiedDefs) { |
| for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) { |
| unsigned Reg = RegOpers.Defs[i]; |
| if (TargetRegisterInfo::isVirtualRegister(Reg) && !LiveRegs.contains(Reg)) |
| UntiedDefs.insert(Reg); |
| } |
| } |
| return true; |
| } |
| |
| /// Advance across the current instruction. |
| bool RegPressureTracker::advance() { |
| assert(!TrackUntiedDefs && "unsupported mode"); |
| |
| // Check for the bottom of the analyzable region. |
| if (CurrPos == MBB->end()) { |
| closeRegion(); |
| return false; |
| } |
| if (!isTopClosed()) |
| closeTop(); |
| |
| SlotIndex SlotIdx; |
| if (RequireIntervals) |
| SlotIdx = getCurrSlot(); |
| |
| // Open the bottom of the region using slot indexes. |
| if (isBottomClosed()) { |
| if (RequireIntervals) |
| static_cast<IntervalPressure&>(P).openBottom(SlotIdx); |
| else |
| static_cast<RegionPressure&>(P).openBottom(CurrPos); |
| } |
| |
| RegisterOperands RegOpers(TRI, MRI); |
| collectOperands(CurrPos, RegOpers); |
| |
| for (unsigned i = 0, e = RegOpers.Uses.size(); i < e; ++i) { |
| unsigned Reg = RegOpers.Uses[i]; |
| // Discover live-ins. |
| bool isLive = LiveRegs.contains(Reg); |
| if (!isLive) |
| discoverLiveIn(Reg); |
| // Kill liveness at last uses. |
| bool lastUse = false; |
| if (RequireIntervals) { |
| const LiveRange *LR = getLiveRange(Reg); |
| lastUse = LR && LR->Query(SlotIdx).isKill(); |
| } |
| else { |
| // Allocatable physregs are always single-use before register rewriting. |
| lastUse = !TargetRegisterInfo::isVirtualRegister(Reg); |
| } |
| if (lastUse && isLive) { |
| LiveRegs.erase(Reg); |
| decreaseRegPressure(Reg); |
| } |
| else if (!lastUse && !isLive) |
| increaseRegPressure(Reg); |
| } |
| |
| // Generate liveness for defs. |
| for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) { |
| unsigned Reg = RegOpers.Defs[i]; |
| if (LiveRegs.insert(Reg)) |
| increaseRegPressure(Reg); |
| } |
| |
| // Boost pressure for all dead defs together. |
| increaseRegPressure(RegOpers.DeadDefs); |
| decreaseRegPressure(RegOpers.DeadDefs); |
| |
| // Find the next instruction. |
| do |
| ++CurrPos; |
| 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 RegisterClassInfo *RCI, |
| ArrayRef<unsigned> LiveThruPressureVec) { |
| Delta.Excess = PressureChange(); |
| 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 = RCI->getRegPressureSetLimit(i); |
| if (!LiveThruPressureVec.empty()) |
| Limit += LiveThruPressureVec[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 (PDiff) { |
| Delta.Excess = PressureChange(i); |
| Delta.Excess.setUnitInc(PDiff); |
| break; |
| } |
| } |
| } |
| |
| /// 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<PressureChange> CriticalPSets, |
| ArrayRef<unsigned> MaxPressureLimit, |
| RegPressureDelta &Delta) { |
| Delta.CriticalMax = PressureChange(); |
| Delta.CurrentMax = PressureChange(); |
| |
| 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; |
| |
| if (!Delta.CriticalMax.isValid()) { |
| while (CritIdx != CritEnd && CriticalPSets[CritIdx].getPSet() < i) |
| ++CritIdx; |
| |
| if (CritIdx != CritEnd && CriticalPSets[CritIdx].getPSet() == i) { |
| int PDiff = (int)PNew - (int)CriticalPSets[CritIdx].getUnitInc(); |
| if (PDiff > 0) { |
| Delta.CriticalMax = PressureChange(i); |
| Delta.CriticalMax.setUnitInc(PDiff); |
| } |
| } |
| } |
| // Find the first increase above MaxPressureLimit. |
| // (Ignores negative MDiff). |
| if (!Delta.CurrentMax.isValid() && PNew > MaxPressureLimit[i]) { |
| Delta.CurrentMax = PressureChange(i); |
| Delta.CurrentMax.setUnitInc(PNew - POld); |
| if (CritIdx == CritEnd || Delta.CriticalMax.isValid()) |
| break; |
| } |
| } |
| } |
| |
| /// 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) { |
| assert(!MI->isDebugValue() && "Expect a nondebug instruction."); |
| |
| // Account for register pressure similar to RegPressureTracker::recede(). |
| RegisterOperands RegOpers(TRI, MRI, /*IgnoreDead=*/true); |
| collectOperands(MI, RegOpers); |
| |
| // Boost max pressure for all dead defs together. |
| // Since CurrSetPressure and MaxSetPressure |
| increaseRegPressure(RegOpers.DeadDefs); |
| decreaseRegPressure(RegOpers.DeadDefs); |
| |
| // Kill liveness at live defs. |
| for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) { |
| unsigned Reg = RegOpers.Defs[i]; |
| bool DeadDef = false; |
| if (RequireIntervals) { |
| const LiveRange *LR = getLiveRange(Reg); |
| if (LR) { |
| SlotIndex SlotIdx = LIS->getInstructionIndex(MI); |
| LiveQueryResult LRQ = LR->Query(SlotIdx); |
| DeadDef = LRQ.isDeadDef(); |
| } |
| } |
| if (!DeadDef) { |
| if (!containsReg(RegOpers.Uses, Reg)) |
| decreaseRegPressure(Reg); |
| } |
| } |
| // Generate liveness for uses. |
| for (unsigned i = 0, e = RegOpers.Uses.size(); i < e; ++i) { |
| unsigned Reg = RegOpers.Uses[i]; |
| if (!LiveRegs.contains(Reg)) |
| increaseRegPressure(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, PressureDiff *PDiff, |
| RegPressureDelta &Delta, |
| ArrayRef<PressureChange> 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, RCI, |
| LiveThruPressure); |
| computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure, CriticalPSets, |
| MaxPressureLimit, Delta); |
| assert(Delta.CriticalMax.getUnitInc() >= 0 && |
| Delta.CurrentMax.getUnitInc() >= 0 && "cannot decrease max pressure"); |
| |
| // Restore the tracker's state. |
| P.MaxSetPressure.swap(SavedMaxPressure); |
| CurrSetPressure.swap(SavedPressure); |
| |
| #ifndef NDEBUG |
| if (!PDiff) |
| return; |
| |
| // Check if the alternate algorithm yields the same result. |
| RegPressureDelta Delta2; |
| getUpwardPressureDelta(MI, *PDiff, Delta2, CriticalPSets, MaxPressureLimit); |
| if (Delta != Delta2) { |
| dbgs() << "DELTA: " << *MI; |
| if (Delta.Excess.isValid()) |
| dbgs() << "Excess1 " << TRI->getRegPressureSetName(Delta.Excess.getPSet()) |
| << " " << Delta.Excess.getUnitInc() << "\n"; |
| if (Delta.CriticalMax.isValid()) |
| dbgs() << "Critic1 " << TRI->getRegPressureSetName(Delta.CriticalMax.getPSet()) |
| << " " << Delta.CriticalMax.getUnitInc() << "\n"; |
| if (Delta.CurrentMax.isValid()) |
| dbgs() << "CurrMx1 " << TRI->getRegPressureSetName(Delta.CurrentMax.getPSet()) |
| << " " << Delta.CurrentMax.getUnitInc() << "\n"; |
| if (Delta2.Excess.isValid()) |
| dbgs() << "Excess2 " << TRI->getRegPressureSetName(Delta2.Excess.getPSet()) |
| << " " << Delta2.Excess.getUnitInc() << "\n"; |
| if (Delta2.CriticalMax.isValid()) |
| dbgs() << "Critic2 " << TRI->getRegPressureSetName(Delta2.CriticalMax.getPSet()) |
| << " " << Delta2.CriticalMax.getUnitInc() << "\n"; |
| if (Delta2.CurrentMax.isValid()) |
| dbgs() << "CurrMx2 " << TRI->getRegPressureSetName(Delta2.CurrentMax.getPSet()) |
| << " " << Delta2.CurrentMax.getUnitInc() << "\n"; |
| llvm_unreachable("RegP Delta Mismatch"); |
| } |
| #endif |
| } |
| |
| /// This is a prototype of the fast version of querying register pressure that |
| /// does not directly depend on current liveness. It's still slow because we |
| /// recompute pressure change on-the-fly. This implementation only exists to |
| /// prove correctness. |
| /// |
| /// @param Delta captures information needed for heuristics. |
| /// |
| /// @param CriticalPSets Are the pressure sets that are known to exceed some |
| /// limit within the region, not necessarily at the current position. |
| /// |
| /// @param MaxPressureLimit Is the max pressure within the region, not |
| /// necessarily at the current position. |
| void RegPressureTracker:: |
| getUpwardPressureDelta(const MachineInstr *MI, /*const*/ PressureDiff &PDiff, |
| RegPressureDelta &Delta, |
| ArrayRef<PressureChange> CriticalPSets, |
| ArrayRef<unsigned> MaxPressureLimit) const { |
| unsigned CritIdx = 0, CritEnd = CriticalPSets.size(); |
| for (PressureDiff::const_iterator |
| PDiffI = PDiff.begin(), PDiffE = PDiff.end(); |
| PDiffI != PDiffE && PDiffI->isValid(); ++PDiffI) { |
| |
| unsigned PSetID = PDiffI->getPSet(); |
| unsigned Limit = RCI->getRegPressureSetLimit(PSetID); |
| if (!LiveThruPressure.empty()) |
| Limit += LiveThruPressure[PSetID]; |
| |
| unsigned POld = CurrSetPressure[PSetID]; |
| unsigned MOld = P.MaxSetPressure[PSetID]; |
| unsigned MNew = MOld; |
| // Ignore DeadDefs here because they aren't captured by PressureChange. |
| unsigned PNew = POld + PDiffI->getUnitInc(); |
| assert((PDiffI->getUnitInc() >= 0) == (PNew >= POld) && "PSet overflow"); |
| if (PNew > MOld) |
| MNew = PNew; |
| // Check if current pressure has exceeded the limit. |
| if (!Delta.Excess.isValid()) { |
| unsigned ExcessInc = 0; |
| if (PNew > Limit) |
| ExcessInc = POld > Limit ? PNew - POld : PNew - Limit; |
| else if (POld > Limit) |
| ExcessInc = Limit - POld; |
| if (ExcessInc) { |
| Delta.Excess = PressureChange(PSetID); |
| Delta.Excess.setUnitInc(ExcessInc); |
| } |
| } |
| // Check if max pressure has exceeded a critical pressure set max. |
| if (MNew == MOld) |
| continue; |
| if (!Delta.CriticalMax.isValid()) { |
| while (CritIdx != CritEnd && CriticalPSets[CritIdx].getPSet() < PSetID) |
| ++CritIdx; |
| |
| if (CritIdx != CritEnd && CriticalPSets[CritIdx].getPSet() == PSetID) { |
| int CritInc = (int)MNew - (int)CriticalPSets[CritIdx].getUnitInc(); |
| if (CritInc > 0 && CritInc <= INT16_MAX) { |
| Delta.CriticalMax = PressureChange(PSetID); |
| Delta.CriticalMax.setUnitInc(CritInc); |
| } |
| } |
| } |
| // Check if max pressure has exceeded the current max. |
| if (!Delta.CurrentMax.isValid() && MNew > MaxPressureLimit[PSetID]) { |
| Delta.CurrentMax = PressureChange(PSetID); |
| Delta.CurrentMax.setUnitInc(MNew - MOld); |
| } |
| } |
| } |
| |
| /// 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_instr_nodbg_iterator |
| UI = MRI->use_instr_nodbg_begin(Reg), |
| UE = MRI->use_instr_nodbg_end(); UI != UE; ++UI) { |
| const MachineInstr* MI = &*UI; |
| if (MI->isDebugValue()) |
| continue; |
| 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) { |
| assert(!MI->isDebugValue() && "Expect a nondebug instruction."); |
| |
| // Account for register pressure similar to RegPressureTracker::recede(). |
| RegisterOperands RegOpers(TRI, MRI); |
| collectOperands(MI, RegOpers); |
| |
| // Kill liveness at last uses. Assume allocatable physregs are single-use |
| // rather than checking LiveIntervals. |
| SlotIndex SlotIdx; |
| if (RequireIntervals) |
| SlotIdx = LIS->getInstructionIndex(MI).getRegSlot(); |
| |
| for (unsigned i = 0, e = RegOpers.Uses.size(); i < e; ++i) { |
| unsigned Reg = RegOpers.Uses[i]; |
| if (RequireIntervals) { |
| // 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 = getCurrSlot(); |
| const LiveRange *LR = getLiveRange(Reg); |
| if (LR) { |
| LiveQueryResult LRQ = LR->Query(SlotIdx); |
| if (LRQ.isKill() && !findUseBetween(Reg, CurrIdx, SlotIdx, MRI, LIS)) { |
| decreaseRegPressure(Reg); |
| } |
| } |
| } |
| else if (!TargetRegisterInfo::isVirtualRegister(Reg)) { |
| // Allocatable physregs are always single-use before register rewriting. |
| decreaseRegPressure(Reg); |
| } |
| } |
| |
| // Generate liveness for defs. |
| increaseRegPressure(RegOpers.Defs); |
| |
| // Boost pressure for all dead defs together. |
| increaseRegPressure(RegOpers.DeadDefs); |
| decreaseRegPressure(RegOpers.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<PressureChange> CriticalPSets, |
| ArrayRef<unsigned> MaxPressureLimit) { |
| // Snapshot Pressure. |
| std::vector<unsigned> SavedPressure = CurrSetPressure; |
| std::vector<unsigned> SavedMaxPressure = P.MaxSetPressure; |
| |
| bumpDownwardPressure(MI); |
| |
| computeExcessPressureDelta(SavedPressure, CurrSetPressure, Delta, RCI, |
| LiveThruPressure); |
| computeMaxPressureDelta(SavedMaxPressure, P.MaxSetPressure, CriticalPSets, |
| MaxPressureLimit, Delta); |
| assert(Delta.CriticalMax.getUnitInc() >= 0 && |
| Delta.CurrentMax.getUnitInc() >= 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); |
| } |