//===-- llvm/CodeGen/LiveInterval.h - Interval representation ---*- C++ -*-===// // // 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 LiveRange and LiveInterval classes. Given some // numbering of each the machine instructions an interval [i, j) is said to be a // live interval for register v if there is no instruction with number j' >= j // such that v is live at j' and there is no instruction with number i' < i such // that v is live at i'. In this implementation intervals can have holes, // i.e. an interval might look like [1,20), [50,65), [1000,1001). Each // individual range is represented as an instance of LiveRange, and the whole // interval is represented as an instance of LiveInterval. // //===----------------------------------------------------------------------===// #ifndef LLVM_CODEGEN_LIVEINTERVAL_H #define LLVM_CODEGEN_LIVEINTERVAL_H #include "llvm/ADT/IntEqClasses.h" #include "llvm/Support/Allocator.h" #include "llvm/Support/AlignOf.h" #include "llvm/CodeGen/SlotIndexes.h" #include <cassert> #include <climits> namespace llvm { class CoalescerPair; class LiveIntervals; class MachineInstr; class MachineRegisterInfo; class TargetRegisterInfo; class raw_ostream; /// VNInfo - Value Number Information. /// This class holds information about a machine level values, including /// definition and use points. /// class VNInfo { public: typedef BumpPtrAllocator Allocator; /// The ID number of this value. unsigned id; /// The index of the defining instruction. SlotIndex def; /// VNInfo constructor. VNInfo(unsigned i, SlotIndex d) : id(i), def(d) { } /// VNInfo construtor, copies values from orig, except for the value number. VNInfo(unsigned i, const VNInfo &orig) : id(i), def(orig.def) { } /// Copy from the parameter into this VNInfo. void copyFrom(VNInfo &src) { def = src.def; } /// Returns true if this value is defined by a PHI instruction (or was, /// PHI instrucions may have been eliminated). /// PHI-defs begin at a block boundary, all other defs begin at register or /// EC slots. bool isPHIDef() const { return def.isBlock(); } /// Returns true if this value is unused. bool isUnused() const { return !def.isValid(); } /// Mark this value as unused. void markUnused() { def = SlotIndex(); } }; /// LiveRange structure - This represents a simple register range in the /// program, with an inclusive start point and an exclusive end point. /// These ranges are rendered as [start,end). struct LiveRange { SlotIndex start; // Start point of the interval (inclusive) SlotIndex end; // End point of the interval (exclusive) VNInfo *valno; // identifier for the value contained in this interval. LiveRange(SlotIndex S, SlotIndex E, VNInfo *V) : start(S), end(E), valno(V) { assert(S < E && "Cannot create empty or backwards range"); } /// contains - Return true if the index is covered by this range. /// bool contains(SlotIndex I) const { return start <= I && I < end; } /// containsRange - Return true if the given range, [S, E), is covered by /// this range. bool containsRange(SlotIndex S, SlotIndex E) const { assert((S < E) && "Backwards interval?"); return (start <= S && S < end) && (start < E && E <= end); } bool operator<(const LiveRange &LR) const { return start < LR.start || (start == LR.start && end < LR.end); } bool operator==(const LiveRange &LR) const { return start == LR.start && end == LR.end; } void dump() const; void print(raw_ostream &os) const; }; template <> struct isPodLike<LiveRange> { static const bool value = true; }; raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR); inline bool operator<(SlotIndex V, const LiveRange &LR) { return V < LR.start; } inline bool operator<(const LiveRange &LR, SlotIndex V) { return LR.start < V; } /// LiveInterval - This class represents some number of live ranges for a /// register or value. This class also contains a bit of register allocator /// state. class LiveInterval { public: typedef SmallVector<LiveRange,4> Ranges; typedef SmallVector<VNInfo*,4> VNInfoList; const unsigned reg; // the register or stack slot of this interval. float weight; // weight of this interval Ranges ranges; // the ranges in which this register is live VNInfoList valnos; // value#'s struct InstrSlots { enum { LOAD = 0, USE = 1, DEF = 2, STORE = 3, NUM = 4 }; }; LiveInterval(unsigned Reg, float Weight) : reg(Reg), weight(Weight) {} typedef Ranges::iterator iterator; iterator begin() { return ranges.begin(); } iterator end() { return ranges.end(); } typedef Ranges::const_iterator const_iterator; const_iterator begin() const { return ranges.begin(); } const_iterator end() const { return ranges.end(); } typedef VNInfoList::iterator vni_iterator; vni_iterator vni_begin() { return valnos.begin(); } vni_iterator vni_end() { return valnos.end(); } typedef VNInfoList::const_iterator const_vni_iterator; const_vni_iterator vni_begin() const { return valnos.begin(); } const_vni_iterator vni_end() const { return valnos.end(); } /// advanceTo - Advance the specified iterator to point to the LiveRange /// containing the specified position, or end() if the position is past the /// end of the interval. If no LiveRange contains this position, but the /// position is in a hole, this method returns an iterator pointing to the /// LiveRange immediately after the hole. iterator advanceTo(iterator I, SlotIndex Pos) { assert(I != end()); if (Pos >= endIndex()) return end(); while (I->end <= Pos) ++I; return I; } /// find - Return an iterator pointing to the first range that ends after /// Pos, or end(). This is the same as advanceTo(begin(), Pos), but faster /// when searching large intervals. /// /// If Pos is contained in a LiveRange, that range is returned. /// If Pos is in a hole, the following LiveRange is returned. /// If Pos is beyond endIndex, end() is returned. iterator find(SlotIndex Pos); const_iterator find(SlotIndex Pos) const { return const_cast<LiveInterval*>(this)->find(Pos); } void clear() { valnos.clear(); ranges.clear(); } bool hasAtLeastOneValue() const { return !valnos.empty(); } bool containsOneValue() const { return valnos.size() == 1; } unsigned getNumValNums() const { return (unsigned)valnos.size(); } /// getValNumInfo - Returns pointer to the specified val#. /// inline VNInfo *getValNumInfo(unsigned ValNo) { return valnos[ValNo]; } inline const VNInfo *getValNumInfo(unsigned ValNo) const { return valnos[ValNo]; } /// containsValue - Returns true if VNI belongs to this interval. bool containsValue(const VNInfo *VNI) const { return VNI && VNI->id < getNumValNums() && VNI == getValNumInfo(VNI->id); } /// getNextValue - Create a new value number and return it. MIIdx specifies /// the instruction that defines the value number. VNInfo *getNextValue(SlotIndex def, VNInfo::Allocator &VNInfoAllocator) { VNInfo *VNI = new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), def); valnos.push_back(VNI); return VNI; } /// createDeadDef - Make sure the interval has a value defined at Def. /// If one already exists, return it. Otherwise allocate a new value and /// add liveness for a dead def. VNInfo *createDeadDef(SlotIndex Def, VNInfo::Allocator &VNInfoAllocator); /// Create a copy of the given value. The new value will be identical except /// for the Value number. VNInfo *createValueCopy(const VNInfo *orig, VNInfo::Allocator &VNInfoAllocator) { VNInfo *VNI = new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), *orig); valnos.push_back(VNI); return VNI; } /// RenumberValues - Renumber all values in order of appearance and remove /// unused values. void RenumberValues(LiveIntervals &lis); /// MergeValueNumberInto - This method is called when two value nubmers /// are found to be equivalent. This eliminates V1, replacing all /// LiveRanges with the V1 value number with the V2 value number. This can /// cause merging of V1/V2 values numbers and compaction of the value space. VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2); /// MergeValueInAsValue - Merge all of the live ranges of a specific val# /// in RHS into this live interval as the specified value number. /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the /// current interval, it will replace the value numbers of the overlaped /// live ranges with the specified value number. void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo); /// MergeValueInAsValue - Merge all of the live ranges of a specific val# /// in RHS into this live interval as the specified value number. /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the /// current interval, but only if the overlapping LiveRanges have the /// specified value number. void MergeValueInAsValue(const LiveInterval &RHS, const VNInfo *RHSValNo, VNInfo *LHSValNo); bool empty() const { return ranges.empty(); } /// beginIndex - Return the lowest numbered slot covered by interval. SlotIndex beginIndex() const { assert(!empty() && "Call to beginIndex() on empty interval."); return ranges.front().start; } /// endNumber - return the maximum point of the interval of the whole, /// exclusive. SlotIndex endIndex() const { assert(!empty() && "Call to endIndex() on empty interval."); return ranges.back().end; } bool expiredAt(SlotIndex index) const { return index >= endIndex(); } bool liveAt(SlotIndex index) const { const_iterator r = find(index); return r != end() && r->start <= index; } /// killedAt - Return true if a live range ends at index. Note that the kill /// point is not contained in the half-open live range. It is usually the /// getDefIndex() slot following its last use. bool killedAt(SlotIndex index) const { const_iterator r = find(index.getRegSlot(true)); return r != end() && r->end == index; } /// getLiveRangeContaining - Return the live range that contains the /// specified index, or null if there is none. const LiveRange *getLiveRangeContaining(SlotIndex Idx) const { const_iterator I = FindLiveRangeContaining(Idx); return I == end() ? 0 : &*I; } /// getLiveRangeContaining - Return the live range that contains the /// specified index, or null if there is none. LiveRange *getLiveRangeContaining(SlotIndex Idx) { iterator I = FindLiveRangeContaining(Idx); return I == end() ? 0 : &*I; } /// getVNInfoAt - Return the VNInfo that is live at Idx, or NULL. VNInfo *getVNInfoAt(SlotIndex Idx) const { const_iterator I = FindLiveRangeContaining(Idx); return I == end() ? 0 : I->valno; } /// getVNInfoBefore - Return the VNInfo that is live up to but not /// necessarilly including Idx, or NULL. Use this to find the reaching def /// used by an instruction at this SlotIndex position. VNInfo *getVNInfoBefore(SlotIndex Idx) const { const_iterator I = FindLiveRangeContaining(Idx.getPrevSlot()); return I == end() ? 0 : I->valno; } /// FindLiveRangeContaining - Return an iterator to the live range that /// contains the specified index, or end() if there is none. iterator FindLiveRangeContaining(SlotIndex Idx) { iterator I = find(Idx); return I != end() && I->start <= Idx ? I : end(); } const_iterator FindLiveRangeContaining(SlotIndex Idx) const { const_iterator I = find(Idx); return I != end() && I->start <= Idx ? I : end(); } /// overlaps - Return true if the intersection of the two live intervals is /// not empty. bool overlaps(const LiveInterval& other) const { if (other.empty()) return false; return overlapsFrom(other, other.begin()); } /// overlaps - Return true if the two intervals have overlapping segments /// that are not coalescable according to CP. /// /// Overlapping segments where one interval is defined by a coalescable /// copy are allowed. bool overlaps(const LiveInterval &Other, const CoalescerPair &CP, const SlotIndexes&) const; /// overlaps - Return true if the live interval overlaps a range specified /// by [Start, End). bool overlaps(SlotIndex Start, SlotIndex End) const; /// overlapsFrom - Return true if the intersection of the two live intervals /// is not empty. The specified iterator is a hint that we can begin /// scanning the Other interval starting at I. bool overlapsFrom(const LiveInterval& other, const_iterator I) const; /// addRange - Add the specified LiveRange to this interval, merging /// intervals as appropriate. This returns an iterator to the inserted live /// range (which may have grown since it was inserted. void addRange(LiveRange LR) { addRangeFrom(LR, ranges.begin()); } /// extendInBlock - If this interval is live before Kill in the basic block /// that starts at StartIdx, extend it to be live up to Kill, and return /// the value. If there is no live range before Kill, return NULL. VNInfo *extendInBlock(SlotIndex StartIdx, SlotIndex Kill); /// join - Join two live intervals (this, and other) together. This applies /// mappings to the value numbers in the LHS/RHS intervals as specified. If /// the intervals are not joinable, this aborts. void join(LiveInterval &Other, const int *ValNoAssignments, const int *RHSValNoAssignments, SmallVector<VNInfo*, 16> &NewVNInfo, MachineRegisterInfo *MRI); /// isInOneLiveRange - Return true if the range specified is entirely in the /// a single LiveRange of the live interval. bool isInOneLiveRange(SlotIndex Start, SlotIndex End) const { const_iterator r = find(Start); return r != end() && r->containsRange(Start, End); } /// removeRange - Remove the specified range from this interval. Note that /// the range must be a single LiveRange in its entirety. void removeRange(SlotIndex Start, SlotIndex End, bool RemoveDeadValNo = false); void removeRange(LiveRange LR, bool RemoveDeadValNo = false) { removeRange(LR.start, LR.end, RemoveDeadValNo); } /// removeValNo - Remove all the ranges defined by the specified value#. /// Also remove the value# from value# list. void removeValNo(VNInfo *ValNo); /// getSize - Returns the sum of sizes of all the LiveRange's. /// unsigned getSize() const; /// Returns true if the live interval is zero length, i.e. no live ranges /// span instructions. It doesn't pay to spill such an interval. bool isZeroLength(SlotIndexes *Indexes) const { for (const_iterator i = begin(), e = end(); i != e; ++i) if (Indexes->getNextNonNullIndex(i->start).getBaseIndex() < i->end.getBaseIndex()) return false; return true; } /// isSpillable - Can this interval be spilled? bool isSpillable() const { return weight != HUGE_VALF; } /// markNotSpillable - Mark interval as not spillable void markNotSpillable() { weight = HUGE_VALF; } bool operator<(const LiveInterval& other) const { const SlotIndex &thisIndex = beginIndex(); const SlotIndex &otherIndex = other.beginIndex(); return (thisIndex < otherIndex || (thisIndex == otherIndex && reg < other.reg)); } void print(raw_ostream &OS) const; void dump() const; /// \brief Walk the interval and assert if any invariants fail to hold. /// /// Note that this is a no-op when asserts are disabled. #ifdef NDEBUG void verify() const {} #else void verify() const; #endif private: Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From); void extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd); Ranges::iterator extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStr); void markValNoForDeletion(VNInfo *V); void mergeIntervalRanges(const LiveInterval &RHS, VNInfo *LHSValNo = 0, const VNInfo *RHSValNo = 0); LiveInterval& operator=(const LiveInterval& rhs) LLVM_DELETED_FUNCTION; }; inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) { LI.print(OS); return OS; } /// LiveRangeQuery - Query information about a live range around a given /// instruction. This class hides the implementation details of live ranges, /// and it should be used as the primary interface for examining live ranges /// around instructions. /// class LiveRangeQuery { VNInfo *EarlyVal; VNInfo *LateVal; SlotIndex EndPoint; bool Kill; public: /// Create a LiveRangeQuery for the given live range and instruction index. /// The sub-instruction slot of Idx doesn't matter, only the instruction it /// refers to is considered. LiveRangeQuery(const LiveInterval &LI, SlotIndex Idx) : EarlyVal(0), LateVal(0), Kill(false) { // Find the segment that enters the instruction. LiveInterval::const_iterator I = LI.find(Idx.getBaseIndex()); LiveInterval::const_iterator E = LI.end(); if (I == E) return; // Is this an instruction live-in segment? // If Idx is the start index of a basic block, include live-in segments // that start at Idx.getBaseIndex(). if (I->start <= Idx.getBaseIndex()) { EarlyVal = I->valno; EndPoint = I->end; // Move to the potentially live-out segment. if (SlotIndex::isSameInstr(Idx, I->end)) { Kill = true; if (++I == E) return; } // Special case: A PHIDef value can have its def in the middle of a // segment if the value happens to be live out of the layout // predecessor. // Such a value is not live-in. if (EarlyVal->def == Idx.getBaseIndex()) EarlyVal = 0; } // I now points to the segment that may be live-through, or defined by // this instr. Ignore segments starting after the current instr. if (SlotIndex::isEarlierInstr(Idx, I->start)) return; LateVal = I->valno; EndPoint = I->end; } /// Return the value that is live-in to the instruction. This is the value /// that will be read by the instruction's use operands. Return NULL if no /// value is live-in. VNInfo *valueIn() const { return EarlyVal; } /// Return true if the live-in value is killed by this instruction. This /// means that either the live range ends at the instruction, or it changes /// value. bool isKill() const { return Kill; } /// Return true if this instruction has a dead def. bool isDeadDef() const { return EndPoint.isDead(); } /// Return the value leaving the instruction, if any. This can be a /// live-through value, or a live def. A dead def returns NULL. VNInfo *valueOut() const { return isDeadDef() ? 0 : LateVal; } /// Return the value defined by this instruction, if any. This includes /// dead defs, it is the value created by the instruction's def operands. VNInfo *valueDefined() const { return EarlyVal == LateVal ? 0 : LateVal; } /// Return the end point of the last live range segment to interact with /// the instruction, if any. /// /// The end point is an invalid SlotIndex only if the live range doesn't /// intersect the instruction at all. /// /// The end point may be at or past the end of the instruction's basic /// block. That means the value was live out of the block. SlotIndex endPoint() const { return EndPoint; } }; /// ConnectedVNInfoEqClasses - Helper class that can divide VNInfos in a /// LiveInterval into equivalence clases of connected components. A /// LiveInterval that has multiple connected components can be broken into /// multiple LiveIntervals. /// /// Given a LiveInterval that may have multiple connected components, run: /// /// unsigned numComps = ConEQ.Classify(LI); /// if (numComps > 1) { /// // allocate numComps-1 new LiveIntervals into LIS[1..] /// ConEQ.Distribute(LIS); /// } class ConnectedVNInfoEqClasses { LiveIntervals &LIS; IntEqClasses EqClass; // Note that values a and b are connected. void Connect(unsigned a, unsigned b); unsigned Renumber(); public: explicit ConnectedVNInfoEqClasses(LiveIntervals &lis) : LIS(lis) {} /// Classify - Classify the values in LI into connected components. /// Return the number of connected components. unsigned Classify(const LiveInterval *LI); /// getEqClass - Classify creates equivalence classes numbered 0..N. Return /// the equivalence class assigned the VNI. unsigned getEqClass(const VNInfo *VNI) const { return EqClass[VNI->id]; } /// Distribute - Distribute values in LIV[0] into a separate LiveInterval /// for each connected component. LIV must have a LiveInterval for each /// connected component. The LiveIntervals in Liv[1..] must be empty. /// Instructions using LIV[0] are rewritten. void Distribute(LiveInterval *LIV[], MachineRegisterInfo &MRI); }; } #endif