X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FCodeGen%2FRegisterPressure.h;h=694d2873c16d8a6d0f36af24d1be60d9cf2ae36f;hb=4af4cbbcedfa811b2d84a0614a2b47a3a685b386;hp=20312be3001247842af89b7e64428c5bd88786da;hpb=17cf53519905acb69c567173bedd2df1c8e45523;p=oota-llvm.git diff --git a/include/llvm/CodeGen/RegisterPressure.h b/include/llvm/CodeGen/RegisterPressure.h index 20312be3001..694d2873c16 100644 --- a/include/llvm/CodeGen/RegisterPressure.h +++ b/include/llvm/CodeGen/RegisterPressure.h @@ -22,6 +22,7 @@ namespace llvm { class LiveIntervals; +class LiveInterval; class RegisterClassInfo; class MachineInstr; @@ -30,18 +31,24 @@ struct RegisterPressure { /// Map of max reg pressure indexed by pressure set ID, not class ID. std::vector MaxSetPressure; - /// List of live in registers. + /// List of live in virtual registers or physical register units. SmallVector LiveInRegs; SmallVector 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). - void increase(const TargetRegisterClass *RC, const TargetRegisterInfo *TRI); + /// + /// \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. - void decrease(const TargetRegisterClass *RC, const TargetRegisterInfo *TRI); + /// + /// \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; }; @@ -82,16 +89,85 @@ struct RegionPressure : RegisterPressure { 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; } - PressureElement(): PSetID(~0U), UnitIncrease(0) {} - PressureElement(unsigned id, int inc): PSetID(id), UnitIncrease(inc) {} + int getUnitInc() const { return UnitInc; } - bool isValid() const { return PSetID != ~0U; } + void setUnitInc(int Inc) { UnitInc = Inc; } + + bool operator==(const PressureChange &RHS) const { + return PSetID == RHS.PSetID && UnitInc == RHS.UnitInc; + } +}; + +template <> struct isPodLike { + 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]; +public: + typedef PressureChange* iterator; + typedef const PressureChange* const_iterator; + iterator begin() { return &PressureChanges[0]; } + iterator end() { return &PressureChanges[MaxPSets]; } + + void addPressureChange(unsigned RegUnit, bool IsDec, + const MachineRegisterInfo *MRI); +}; + +/// Array of PressureDiffs. +class PressureDiffs { + PressureDiff *PDiffArray; + unsigned Size; + unsigned Max; +public: + PressureDiffs(): PDiffArray(0), Size(0), Max(0) {} + ~PressureDiffs() { free(PDiffArray); } + + void init(unsigned N); + + PressureDiff &operator[](unsigned Idx) { + assert(Idx < Size && "PressureDiff index out of bounds"); + return PDiffArray[Idx]; + } + const PressureDiff &operator[](unsigned Idx) const { + return const_cast(this)->operator[](Idx); + } }; /// Store the effects of a change in pressure on things that MI scheduler cares @@ -109,11 +185,46 @@ struct PressureElement { /// 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. +/// +/// Virtual and physical register numbers require separate sparse sets, but most +/// of the RegisterPressureTracker handles them uniformly. +struct LiveRegSet { + SparseSet PhysRegs; + SparseSet VirtRegs; + + bool contains(unsigned Reg) const { + if (TargetRegisterInfo::isVirtualRegister(Reg)) + return VirtRegs.count(Reg); + return PhysRegs.count(Reg); + } + + bool insert(unsigned Reg) { + if (TargetRegisterInfo::isVirtualRegister(Reg)) + return VirtRegs.insert(Reg).second; + return PhysRegs.insert(Reg).second; + } + + bool erase(unsigned Reg) { + if (TargetRegisterInfo::isVirtualRegister(Reg)) + return VirtRegs.erase(Reg); + return PhysRegs.erase(Reg); + } }; /// Track the current register pressure at some position in the instruction @@ -149,6 +260,9 @@ class RegPressureTracker { /// 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. @@ -157,23 +271,31 @@ class RegPressureTracker { /// Pressure map indexed by pressure set ID, not class ID. std::vector CurrSetPressure; - /// List of live registers. - SparseSet LivePhysRegs; - SparseSet LiveVirtRegs; + /// Set of live registers. + LiveRegSet LiveRegs; + + /// Set of vreg defs that start a live range. + SparseSet UntiedDefs; + /// Live-through pressure. + std::vector LiveThruPressure; public: RegPressureTracker(IntervalPressure &rp) : - MF(0), TRI(0), RCI(0), LIS(0), MBB(0), P(rp), RequireIntervals(true) {} + MF(0), TRI(0), RCI(0), LIS(0), MBB(0), P(rp), RequireIntervals(true), + TrackUntiedDefs(false) {} RegPressureTracker(RegionPressure &rp) : - MF(0), TRI(0), RCI(0), LIS(0), MBB(0), P(rp), RequireIntervals(false) {} + MF(0), TRI(0), RCI(0), LIS(0), MBB(0), P(rp), RequireIntervals(false), + TrackUntiedDefs(false) {} 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 registers. Particularly useful to initialize the - /// livein/out state of the tracker before the first call to advance/recede. + /// Force liveness of virtual registers or physical register + /// units. Particularly useful to initialize the livein/out state of the + /// tracker before the first call to advance/recede. void addLiveRegs(ArrayRef Regs); /// Get the MI position corresponding to this register pressure. @@ -190,7 +312,7 @@ public: SlotIndex getCurrSlot() const; /// Recede across the previous instruction. - bool recede(); + bool recede(SmallVectorImpl *LiveUses = 0, PressureDiff *PDiff = 0); /// Advance across the current instruction. bool advance(); @@ -198,6 +320,17 @@ public: /// 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 PressureSet) { + LiveThruPressure.assign(PressureSet.begin(), PressureSet.end()); + } + + ArrayRef 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. @@ -208,11 +341,8 @@ public: /// than the pressure across the traversed region. std::vector &getRegSetPressureAtPos() { return CurrSetPressure; } - void discoverPhysLiveIn(unsigned Reg); - void discoverPhysLiveOut(unsigned Reg); - - void discoverVirtLiveIn(unsigned Reg); - void discoverVirtLiveOut(unsigned Reg); + void discoverLiveOut(unsigned Reg); + void discoverLiveIn(unsigned Reg); bool isTopClosed() const; bool isBottomClosed() const; @@ -225,31 +355,39 @@ public: /// 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 CriticalPSets, + ArrayRef CriticalPSets, ArrayRef MaxPressureLimit); + void getUpwardPressureDelta(const MachineInstr *MI, + /*const*/ PressureDiff &PDiff, + RegPressureDelta &Delta, + ArrayRef CriticalPSets, + ArrayRef 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 CriticalPSets, + ArrayRef CriticalPSets, ArrayRef 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 CriticalPSets, + void getMaxPressureDelta(const MachineInstr *MI, + RegPressureDelta &Delta, + ArrayRef CriticalPSets, ArrayRef MaxPressureLimit) { if (isTopClosed()) return getMaxDownwardPressureDelta(MI, Delta, CriticalPSets, MaxPressureLimit); assert(isBottomClosed() && "Uninitialized pressure tracker"); - return getMaxUpwardPressureDelta(MI, Delta, CriticalPSets, + return getMaxUpwardPressureDelta(MI, 0, Delta, CriticalPSets, MaxPressureLimit); } @@ -273,18 +411,26 @@ public: return getDownwardPressure(MI, PressureResult, MaxPressureResult); } - void dump(const TargetRegisterInfo *TRI) const; + bool hasUntiedDef(unsigned VirtReg) const { + return UntiedDefs.count(VirtReg); + } + + void dump() const; protected: - void increasePhysRegPressure(ArrayRef Regs); - void decreasePhysRegPressure(ArrayRef Regs); + const LiveInterval *getInterval(unsigned Reg) const; - void increaseVirtRegPressure(ArrayRef Regs); - void decreaseVirtRegPressure(ArrayRef Regs); + void increaseRegPressure(ArrayRef Regs); + void decreaseRegPressure(ArrayRef Regs); void bumpUpwardPressure(const MachineInstr *MI); void bumpDownwardPressure(const MachineInstr *MI); }; + +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) +void dumpRegSetPressure(ArrayRef SetPressure, + const TargetRegisterInfo *TRI); +#endif } // end namespace llvm #endif