namespace llvm {
class LiveIntervals;
-class LiveInterval;
+class LiveRange;
class RegisterClassInfo;
class MachineInstr;
SmallVector<unsigned,8> LiveInRegs;
SmallVector<unsigned,8> LiveOutRegs;
- /// Increase register pressure for each pressure set impacted by this register
- /// class. Normally called by RegPressureTracker, but may be called manually
- /// to account for live through (global liveness).
- ///
- /// \param Reg is either a virtual register number or register unit number.
- void increase(unsigned Reg, const TargetRegisterInfo *TRI,
- const MachineRegisterInfo *MRI);
-
- /// Decrease register pressure for each pressure set impacted by this register
- /// class. This is only useful to account for spilling or rematerialization.
- ///
- /// \param Reg is either a virtual register number or register unit number.
- void decrease(unsigned Reg, const TargetRegisterInfo *TRI,
- const MachineRegisterInfo *MRI);
-
void dump(const TargetRegisterInfo *TRI) const;
};
void openBottom(MachineBasicBlock::const_iterator PrevBottom);
};
-/// An element of pressure difference that identifies the pressure set and
-/// amount of increase or decrease in units of pressure.
-struct PressureElement {
- unsigned PSetID;
- int UnitIncrease;
+/// Capture a change in pressure for a single pressure set. UnitInc may be
+/// expressed in terms of upward or downward pressure depending on the client
+/// and will be dynamically adjusted for current liveness.
+///
+/// Pressure increments are tiny, typically 1-2 units, and this is only for
+/// heuristics, so we don't check UnitInc overflow. Instead, we may have a
+/// higher level assert that pressure is consistent within a region. We also
+/// effectively ignore dead defs which don't affect heuristics much.
+class PressureChange {
+ uint16_t PSetID; // ID+1. 0=Invalid.
+ int16_t UnitInc;
+public:
+ PressureChange(): PSetID(0), UnitInc(0) {}
+ PressureChange(unsigned id): PSetID(id+1), UnitInc(0) {
+ assert(id < UINT16_MAX && "PSetID overflow.");
+ }
+
+ bool isValid() const { return PSetID > 0; }
+
+ unsigned getPSet() const {
+ assert(isValid() && "invalid PressureChange");
+ return PSetID - 1;
+ }
+ // If PSetID is invalid, return UINT16_MAX to give it lowest priority.
+ unsigned getPSetOrMax() const { return (PSetID - 1) & UINT16_MAX; }
+
+ int getUnitInc() const { return UnitInc; }
+
+ void setUnitInc(int Inc) { UnitInc = Inc; }
+
+ bool operator==(const PressureChange &RHS) const {
+ return PSetID == RHS.PSetID && UnitInc == RHS.UnitInc;
+ }
+};
+
+template <> struct isPodLike<PressureChange> {
+ static const bool value = true;
+};
+
+/// List of PressureChanges in order of increasing, unique PSetID.
+///
+/// Use a small fixed number, because we can fit more PressureChanges in an
+/// empty SmallVector than ever need to be tracked per register class. If more
+/// PSets are affected, then we only track the most constrained.
+class PressureDiff {
+ // The initial design was for MaxPSets=4, but that requires PSet partitions,
+ // which are not yet implemented. (PSet partitions are equivalent PSets given
+ // the register classes actually in use within the scheduling region.)
+ enum { MaxPSets = 16 };
+
+ PressureChange PressureChanges[MaxPSets];
+
+ typedef PressureChange* iterator;
+ iterator nonconst_begin() { return &PressureChanges[0]; }
+ iterator nonconst_end() { return &PressureChanges[MaxPSets]; }
+
+public:
+ typedef const PressureChange* const_iterator;
+ const_iterator begin() const { return &PressureChanges[0]; }
+ const_iterator end() const { return &PressureChanges[MaxPSets]; }
+
+ void addPressureChange(unsigned RegUnit, bool IsDec,
+ const MachineRegisterInfo *MRI);
+
+ LLVM_DUMP_METHOD void dump(const TargetRegisterInfo &TRI) const;
+};
+
+/// List of registers defined and used by a machine instruction.
+class RegisterOperands {
+public:
+ /// List of virtual regiserts and register units read by the instruction.
+ SmallVector<unsigned, 8> Uses;
+ /// \brief List of virtual registers and register units defined by the
+ /// instruction which are not dead.
+ SmallVector<unsigned, 8> Defs;
+ /// \brief List of virtual registers and register units defined by the
+ /// instruction but dead.
+ SmallVector<unsigned, 8> DeadDefs;
+
+ /// Analyze the given instruction \p MI and fill in the Uses, Defs and
+ /// DeadDefs list based on the MachineOperand flags.
+ void collect(const MachineInstr &MI, const TargetRegisterInfo &TRI,
+ const MachineRegisterInfo &MRI, bool IgnoreDead = false);
+
+ /// Use liveness information to find dead defs not marked with a dead flag
+ /// and move them to the DeadDefs vector.
+ void detectDeadDefs(const MachineInstr &MI, const LiveIntervals &LIS);
+};
+
+/// Array of PressureDiffs.
+class PressureDiffs {
+ PressureDiff *PDiffArray;
+ unsigned Size;
+ unsigned Max;
+public:
+ PressureDiffs(): PDiffArray(nullptr), Size(0), Max(0) {}
+ ~PressureDiffs() { free(PDiffArray); }
- PressureElement(): PSetID(~0U), UnitIncrease(0) {}
- PressureElement(unsigned id, int inc): PSetID(id), UnitIncrease(inc) {}
+ void clear() { Size = 0; }
- bool isValid() const { return PSetID != ~0U; }
+ void init(unsigned N);
- // If signed PSetID is negative, it is invalid; convert it to INT_MAX to give
- // it lowest priority.
- int PSetRank() const { return PSetID & INT_MAX; }
+ PressureDiff &operator[](unsigned Idx) {
+ assert(Idx < Size && "PressureDiff index out of bounds");
+ return PDiffArray[Idx];
+ }
+ const PressureDiff &operator[](unsigned Idx) const {
+ return const_cast<PressureDiffs*>(this)->operator[](Idx);
+ }
+ /// \brief Record pressure difference induced by the given operand list to
+ /// node with index \p Idx.
+ void addInstruction(unsigned Idx, const RegisterOperands &RegOpers,
+ const MachineRegisterInfo &MRI);
};
/// Store the effects of a change in pressure on things that MI scheduler cares
/// CurrentMax records the largest increase in the tracker's max pressure that
/// exceeds the current limit for some pressure set determined by the client.
struct RegPressureDelta {
- PressureElement Excess;
- PressureElement CriticalMax;
- PressureElement CurrentMax;
+ PressureChange Excess;
+ PressureChange CriticalMax;
+ PressureChange CurrentMax;
RegPressureDelta() {}
+
+ bool operator==(const RegPressureDelta &RHS) const {
+ return Excess == RHS.Excess && CriticalMax == RHS.CriticalMax
+ && CurrentMax == RHS.CurrentMax;
+ }
+ bool operator!=(const RegPressureDelta &RHS) const {
+ return !operator==(RHS);
+ }
};
-/// \brief A set of live virtual registers and physical register units.
+/// A set of live virtual registers and physical register units.
///
-/// Virtual and physical register numbers require separate sparse sets, but most
-/// of the RegisterPressureTracker handles them uniformly.
-struct LiveRegSet {
- SparseSet<unsigned> PhysRegs;
- SparseSet<unsigned, VirtReg2IndexFunctor> VirtRegs;
-
- bool contains(unsigned Reg) {
+/// This is a wrapper around a SparseSet which deals with mapping register unit
+/// and virtual register indexes to an index usable by the sparse set.
+class LiveRegSet {
+private:
+ SparseSet<unsigned> Regs;
+ unsigned NumRegUnits;
+
+ unsigned getSparseIndexFromReg(unsigned Reg) const {
if (TargetRegisterInfo::isVirtualRegister(Reg))
- return VirtRegs.count(Reg);
- return PhysRegs.count(Reg);
+ return TargetRegisterInfo::virtReg2Index(Reg) + NumRegUnits;
+ assert(Reg < NumRegUnits);
+ return Reg;
+ }
+ unsigned getRegFromSparseIndex(unsigned SparseIndex) const {
+ if (SparseIndex >= NumRegUnits)
+ return TargetRegisterInfo::index2VirtReg(SparseIndex-NumRegUnits);
+ return SparseIndex;
+ }
+
+public:
+ void clear();
+ void init(const MachineRegisterInfo &MRI);
+
+ bool contains(unsigned Reg) const {
+ unsigned SparseIndex = getSparseIndexFromReg(Reg);
+ return Regs.count(SparseIndex);
}
bool insert(unsigned Reg) {
- if (TargetRegisterInfo::isVirtualRegister(Reg))
- return VirtRegs.insert(Reg).second;
- return PhysRegs.insert(Reg).second;
+ unsigned SparseIndex = getSparseIndexFromReg(Reg);
+ return Regs.insert(SparseIndex).second;
}
bool erase(unsigned Reg) {
- if (TargetRegisterInfo::isVirtualRegister(Reg))
- return VirtRegs.erase(Reg);
- return PhysRegs.erase(Reg);
+ unsigned SparseIndex = getSparseIndexFromReg(Reg);
+ return Regs.erase(SparseIndex);
+ }
+
+ size_t size() const {
+ return Regs.size();
+ }
+
+ template<typename ContainerT>
+ void appendTo(ContainerT &To) const {
+ for (unsigned I : Regs) {
+ unsigned Reg = getRegFromSparseIndex(I);
+ To.push_back(Reg);
+ }
}
};
/// or RegisterPressure. If requireIntervals is false, LIS are ignored.
bool RequireIntervals;
+ /// True if UntiedDefs will be populated.
+ bool TrackUntiedDefs;
+
/// Register pressure corresponds to liveness before this instruction
/// iterator. It may point to the end of the block or a DebugValue rather than
/// an instruction.
/// Set of live registers.
LiveRegSet LiveRegs;
+ /// Set of vreg defs that start a live range.
+ SparseSet<unsigned, VirtReg2IndexFunctor> UntiedDefs;
+ /// Live-through pressure.
+ std::vector<unsigned> LiveThruPressure;
+
public:
RegPressureTracker(IntervalPressure &rp) :
- MF(0), TRI(0), RCI(0), LIS(0), MBB(0), P(rp), RequireIntervals(true) {}
+ MF(nullptr), TRI(nullptr), RCI(nullptr), LIS(nullptr), MBB(nullptr), P(rp),
+ RequireIntervals(true), TrackUntiedDefs(false) {}
RegPressureTracker(RegionPressure &rp) :
- MF(0), TRI(0), RCI(0), LIS(0), MBB(0), P(rp), RequireIntervals(false) {}
+ MF(nullptr), TRI(nullptr), RCI(nullptr), LIS(nullptr), MBB(nullptr), P(rp),
+ RequireIntervals(false), TrackUntiedDefs(false) {}
+
+ void reset();
void init(const MachineFunction *mf, const RegisterClassInfo *rci,
const LiveIntervals *lis, const MachineBasicBlock *mbb,
- MachineBasicBlock::const_iterator pos);
+ MachineBasicBlock::const_iterator pos,
+ bool ShouldTrackUntiedDefs = false);
/// Force liveness of virtual registers or physical register
/// units. Particularly useful to initialize the livein/out state of the
// position changes while pressure does not.
void setPos(MachineBasicBlock::const_iterator Pos) { CurrPos = Pos; }
- /// \brief Get the SlotIndex for the first nondebug instruction including or
- /// after the current position.
- SlotIndex getCurrSlot() const;
+ /// Recede across the previous instruction.
+ void recede(SmallVectorImpl<unsigned> *LiveUses = nullptr);
/// Recede across the previous instruction.
- bool recede();
+ /// This "low-level" variant assumes that recedeSkipDebugValues() was
+ /// called previously and takes precomputed RegisterOperands for the
+ /// instruction.
+ void recede(const RegisterOperands &RegOpers,
+ SmallVectorImpl<unsigned> *LiveUses = nullptr);
+
+ /// Recede until we find an instruction which is not a DebugValue.
+ void recedeSkipDebugValues();
/// Advance across the current instruction.
- bool advance();
+ void advance();
/// Finalize the region boundaries and recored live ins and live outs.
void closeRegion();
+ /// Initialize the LiveThru pressure set based on the untied defs found in
+ /// RPTracker.
+ void initLiveThru(const RegPressureTracker &RPTracker);
+
+ /// Copy an existing live thru pressure result.
+ void initLiveThru(ArrayRef<unsigned> PressureSet) {
+ LiveThruPressure.assign(PressureSet.begin(), PressureSet.end());
+ }
+
+ ArrayRef<unsigned> getLiveThru() const { return LiveThruPressure; }
+
/// Get the resulting register pressure over the traversed region.
- /// This result is complete if either advance() or recede() has returned true,
- /// or if closeRegion() was explicitly invoked.
+ /// This result is complete if closeRegion() was explicitly invoked.
RegisterPressure &getPressure() { return P; }
const RegisterPressure &getPressure() const { return P; }
/// Get the register set pressure at the current position, which may be less
/// than the pressure across the traversed region.
- std::vector<unsigned> &getRegSetPressureAtPos() { return CurrSetPressure; }
-
- void discoverLiveOut(unsigned Reg);
- void discoverLiveIn(unsigned Reg);
+ const std::vector<unsigned> &getRegSetPressureAtPos() const {
+ return CurrSetPressure;
+ }
bool isTopClosed() const;
bool isBottomClosed() const;
/// limit based on the tracker's current pressure, and record the number of
/// excess register units of that pressure set introduced by this instruction.
void getMaxUpwardPressureDelta(const MachineInstr *MI,
+ PressureDiff *PDiff,
RegPressureDelta &Delta,
- ArrayRef<PressureElement> CriticalPSets,
+ ArrayRef<PressureChange> CriticalPSets,
ArrayRef<unsigned> MaxPressureLimit);
+ void getUpwardPressureDelta(const MachineInstr *MI,
+ /*const*/ PressureDiff &PDiff,
+ RegPressureDelta &Delta,
+ ArrayRef<PressureChange> CriticalPSets,
+ ArrayRef<unsigned> MaxPressureLimit) const;
+
/// Consider the pressure increase caused by traversing this instruction
/// top-down. Find the pressure set with the most change beyond its pressure
/// limit based on the tracker's current pressure, and record the number of
/// excess register units of that pressure set introduced by this instruction.
void getMaxDownwardPressureDelta(const MachineInstr *MI,
RegPressureDelta &Delta,
- ArrayRef<PressureElement> CriticalPSets,
+ ArrayRef<PressureChange> CriticalPSets,
ArrayRef<unsigned> MaxPressureLimit);
/// Find the pressure set with the most change beyond its pressure limit after
/// traversing this instruction either upward or downward depending on the
/// closed end of the current region.
- void getMaxPressureDelta(const MachineInstr *MI, RegPressureDelta &Delta,
- ArrayRef<PressureElement> CriticalPSets,
+ void getMaxPressureDelta(const MachineInstr *MI,
+ RegPressureDelta &Delta,
+ ArrayRef<PressureChange> CriticalPSets,
ArrayRef<unsigned> MaxPressureLimit) {
if (isTopClosed())
return getMaxDownwardPressureDelta(MI, Delta, CriticalPSets,
MaxPressureLimit);
assert(isBottomClosed() && "Uninitialized pressure tracker");
- return getMaxUpwardPressureDelta(MI, Delta, CriticalPSets,
+ return getMaxUpwardPressureDelta(MI, nullptr, Delta, CriticalPSets,
MaxPressureLimit);
}
return getDownwardPressure(MI, PressureResult, MaxPressureResult);
}
+ bool hasUntiedDef(unsigned VirtReg) const {
+ return UntiedDefs.count(VirtReg);
+ }
+
void dump() const;
protected:
- const LiveInterval *getInterval(unsigned Reg) const;
+ void discoverLiveOut(unsigned Reg);
+ void discoverLiveIn(unsigned Reg);
+
+ /// \brief Get the SlotIndex for the first nondebug instruction including or
+ /// after the current position.
+ SlotIndex getCurrSlot() const;
void increaseRegPressure(ArrayRef<unsigned> Regs);
void decreaseRegPressure(ArrayRef<unsigned> Regs);
void bumpUpwardPressure(const MachineInstr *MI);
void bumpDownwardPressure(const MachineInstr *MI);
};
+
+void dumpRegSetPressure(ArrayRef<unsigned> SetPressure,
+ const TargetRegisterInfo *TRI);
} // end namespace llvm
#endif
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