1 //===-- llvm/CodeGen/LiveInterval.h - Interval representation ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LiveRange and LiveInterval classes. Given some
11 // numbering of each the machine instructions an interval [i, j) is said to be a
12 // live interval for register v if there is no instruction with number j' >= j
13 // such that v is live at j' and there is no instruction with number i' < i such
14 // that v is live at i'. In this implementation intervals can have holes,
15 // i.e. an interval might look like [1,20), [50,65), [1000,1001). Each
16 // individual range is represented as an instance of LiveRange, and the whole
17 // interval is represented as an instance of LiveInterval.
19 //===----------------------------------------------------------------------===//
21 #ifndef LLVM_CODEGEN_LIVEINTERVAL_H
22 #define LLVM_CODEGEN_LIVEINTERVAL_H
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/Support/Allocator.h"
26 #include "llvm/Support/AlignOf.h"
27 #include "llvm/CodeGen/SlotIndexes.h"
34 class MachineRegisterInfo;
35 class TargetRegisterInfo;
38 /// VNInfo - Value Number Information.
39 /// This class holds information about a machine level values, including
40 /// definition and use points.
55 typedef BumpPtrAllocator Allocator;
57 /// The ID number of this value.
60 /// The index of the defining instruction (if isDefAccurate() returns true).
63 /// VNInfo constructor.
64 VNInfo(unsigned i, SlotIndex d, MachineInstr *c)
65 : copy(c), flags(0), id(i), def(d)
68 /// VNInfo construtor, copies values from orig, except for the value number.
69 VNInfo(unsigned i, const VNInfo &orig)
70 : copy(orig.copy), flags(orig.flags), id(i), def(orig.def)
73 /// Copy from the parameter into this VNInfo.
74 void copyFrom(VNInfo &src) {
80 /// Used for copying value number info.
81 unsigned getFlags() const { return flags; }
82 void setFlags(unsigned flags) { this->flags = flags; }
84 /// Merge flags from another VNInfo
85 void mergeFlags(const VNInfo *VNI) {
86 flags = (flags | VNI->flags) & ~IS_UNUSED;
89 /// For a register interval, if this VN was definied by a copy instr
90 /// getCopy() returns a pointer to it, otherwise returns 0.
91 /// For a stack interval the behaviour of this method is undefined.
92 MachineInstr* getCopy() const { return copy; }
93 /// For a register interval, set the copy member.
94 /// This method should not be called on stack intervals as it may lead to
95 /// undefined behavior.
96 void setCopy(MachineInstr *c) { copy = c; }
98 /// isDefByCopy - Return true when this value was defined by a copy-like
99 /// instruction as determined by MachineInstr::isCopyLike.
100 bool isDefByCopy() const { return copy != 0; }
102 /// Returns true if one or more kills are PHI nodes.
103 bool hasPHIKill() const { return flags & HAS_PHI_KILL; }
104 /// Set the PHI kill flag on this value.
105 void setHasPHIKill(bool hasKill) {
107 flags |= HAS_PHI_KILL;
109 flags &= ~HAS_PHI_KILL;
112 /// Returns true if this value is re-defined by an early clobber somewhere
113 /// during the live range.
114 bool hasRedefByEC() const { return flags & REDEF_BY_EC; }
115 /// Set the "redef by early clobber" flag on this value.
116 void setHasRedefByEC(bool hasRedef) {
118 flags |= REDEF_BY_EC;
120 flags &= ~REDEF_BY_EC;
123 /// Returns true if this value is defined by a PHI instruction (or was,
124 /// PHI instrucions may have been eliminated).
125 bool isPHIDef() const { return flags & IS_PHI_DEF; }
126 /// Set the "phi def" flag on this value.
127 void setIsPHIDef(bool phiDef) {
131 flags &= ~IS_PHI_DEF;
134 /// Returns true if this value is unused.
135 bool isUnused() const { return flags & IS_UNUSED; }
136 /// Set the "is unused" flag on this value.
137 void setIsUnused(bool unused) {
145 /// LiveRange structure - This represents a simple register range in the
146 /// program, with an inclusive start point and an exclusive end point.
147 /// These ranges are rendered as [start,end).
149 SlotIndex start; // Start point of the interval (inclusive)
150 SlotIndex end; // End point of the interval (exclusive)
151 VNInfo *valno; // identifier for the value contained in this interval.
153 LiveRange(SlotIndex S, SlotIndex E, VNInfo *V)
154 : start(S), end(E), valno(V) {
156 assert(S < E && "Cannot create empty or backwards range");
159 /// contains - Return true if the index is covered by this range.
161 bool contains(SlotIndex I) const {
162 return start <= I && I < end;
165 /// containsRange - Return true if the given range, [S, E), is covered by
167 bool containsRange(SlotIndex S, SlotIndex E) const {
168 assert((S < E) && "Backwards interval?");
169 return (start <= S && S < end) && (start < E && E <= end);
172 bool operator<(const LiveRange &LR) const {
173 return start < LR.start || (start == LR.start && end < LR.end);
175 bool operator==(const LiveRange &LR) const {
176 return start == LR.start && end == LR.end;
180 void print(raw_ostream &os) const;
183 LiveRange(); // DO NOT IMPLEMENT
186 template <> struct isPodLike<LiveRange> { static const bool value = true; };
188 raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR);
191 inline bool operator<(SlotIndex V, const LiveRange &LR) {
195 inline bool operator<(const LiveRange &LR, SlotIndex V) {
199 /// LiveInterval - This class represents some number of live ranges for a
200 /// register or value. This class also contains a bit of register allocator
205 typedef SmallVector<LiveRange,4> Ranges;
206 typedef SmallVector<VNInfo*,4> VNInfoList;
208 unsigned reg; // the register or stack slot of this interval
209 // if the top bits is set, it represents a stack slot.
210 float weight; // weight of this interval
211 Ranges ranges; // the ranges in which this register is live
212 VNInfoList valnos; // value#'s
225 LiveInterval(unsigned Reg, float Weight, bool IsSS = false)
226 : reg(Reg), weight(Weight) {
228 reg = reg | (1U << (sizeof(unsigned)*CHAR_BIT-1));
231 typedef Ranges::iterator iterator;
232 iterator begin() { return ranges.begin(); }
233 iterator end() { return ranges.end(); }
235 typedef Ranges::const_iterator const_iterator;
236 const_iterator begin() const { return ranges.begin(); }
237 const_iterator end() const { return ranges.end(); }
239 typedef VNInfoList::iterator vni_iterator;
240 vni_iterator vni_begin() { return valnos.begin(); }
241 vni_iterator vni_end() { return valnos.end(); }
243 typedef VNInfoList::const_iterator const_vni_iterator;
244 const_vni_iterator vni_begin() const { return valnos.begin(); }
245 const_vni_iterator vni_end() const { return valnos.end(); }
247 /// advanceTo - Advance the specified iterator to point to the LiveRange
248 /// containing the specified position, or end() if the position is past the
249 /// end of the interval. If no LiveRange contains this position, but the
250 /// position is in a hole, this method returns an iterator pointing to the
251 /// LiveRange immediately after the hole.
252 iterator advanceTo(iterator I, SlotIndex Pos) {
253 if (Pos >= endIndex())
255 while (I->end <= Pos) ++I;
259 /// find - Return an iterator pointing to the first range that ends after
260 /// Pos, or end(). This is the same as advanceTo(begin(), Pos), but faster
261 /// when searching large intervals.
263 /// If Pos is contained in a LiveRange, that range is returned.
264 /// If Pos is in a hole, the following LiveRange is returned.
265 /// If Pos is beyond endIndex, end() is returned.
266 iterator find(SlotIndex Pos);
268 const_iterator find(SlotIndex Pos) const {
269 return const_cast<LiveInterval*>(this)->find(Pos);
277 /// isStackSlot - Return true if this is a stack slot interval.
279 bool isStackSlot() const {
280 return reg & (1U << (sizeof(unsigned)*CHAR_BIT-1));
283 /// getStackSlotIndex - Return stack slot index if this is a stack slot
285 int getStackSlotIndex() const {
286 assert(isStackSlot() && "Interval is not a stack slot interval!");
287 return reg & ~(1U << (sizeof(unsigned)*CHAR_BIT-1));
290 bool hasAtLeastOneValue() const { return !valnos.empty(); }
292 bool containsOneValue() const { return valnos.size() == 1; }
294 unsigned getNumValNums() const { return (unsigned)valnos.size(); }
296 /// getValNumInfo - Returns pointer to the specified val#.
298 inline VNInfo *getValNumInfo(unsigned ValNo) {
299 return valnos[ValNo];
301 inline const VNInfo *getValNumInfo(unsigned ValNo) const {
302 return valnos[ValNo];
305 /// getNextValue - Create a new value number and return it. MIIdx specifies
306 /// the instruction that defines the value number.
307 VNInfo *getNextValue(SlotIndex def, MachineInstr *CopyMI,
308 VNInfo::Allocator &VNInfoAllocator) {
310 new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), def, CopyMI);
311 valnos.push_back(VNI);
315 /// Create a copy of the given value. The new value will be identical except
316 /// for the Value number.
317 VNInfo *createValueCopy(const VNInfo *orig,
318 VNInfo::Allocator &VNInfoAllocator) {
320 new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), *orig);
321 valnos.push_back(VNI);
325 /// RenumberValues - Renumber all values in order of appearance and remove
327 /// Recalculate phi-kill flags in case any phi-def values were removed.
328 void RenumberValues(LiveIntervals &lis);
330 /// isOnlyLROfValNo - Return true if the specified live range is the only
331 /// one defined by the its val#.
332 bool isOnlyLROfValNo(const LiveRange *LR) {
333 for (const_iterator I = begin(), E = end(); I != E; ++I) {
334 const LiveRange *Tmp = I;
335 if (Tmp != LR && Tmp->valno == LR->valno)
341 /// MergeValueNumberInto - This method is called when two value nubmers
342 /// are found to be equivalent. This eliminates V1, replacing all
343 /// LiveRanges with the V1 value number with the V2 value number. This can
344 /// cause merging of V1/V2 values numbers and compaction of the value space.
345 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2);
347 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
348 /// in RHS into this live interval as the specified value number.
349 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
350 /// current interval, it will replace the value numbers of the overlaped
351 /// live ranges with the specified value number.
352 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo);
354 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
355 /// in RHS into this live interval as the specified value number.
356 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
357 /// current interval, but only if the overlapping LiveRanges have the
358 /// specified value number.
359 void MergeValueInAsValue(const LiveInterval &RHS,
360 const VNInfo *RHSValNo, VNInfo *LHSValNo);
362 /// Copy - Copy the specified live interval. This copies all the fields
363 /// except for the register of the interval.
364 void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI,
365 VNInfo::Allocator &VNInfoAllocator);
367 bool empty() const { return ranges.empty(); }
369 /// beginIndex - Return the lowest numbered slot covered by interval.
370 SlotIndex beginIndex() const {
371 assert(!empty() && "Call to beginIndex() on empty interval.");
372 return ranges.front().start;
375 /// endNumber - return the maximum point of the interval of the whole,
377 SlotIndex endIndex() const {
378 assert(!empty() && "Call to endIndex() on empty interval.");
379 return ranges.back().end;
382 bool expiredAt(SlotIndex index) const {
383 return index >= endIndex();
386 bool liveAt(SlotIndex index) const {
387 const_iterator r = find(index);
388 return r != end() && r->start <= index;
391 /// killedAt - Return true if a live range ends at index. Note that the kill
392 /// point is not contained in the half-open live range. It is usually the
393 /// getDefIndex() slot following its last use.
394 bool killedAt(SlotIndex index) const {
395 const_iterator r = find(index.getUseIndex());
396 return r != end() && r->end == index;
399 /// killedInRange - Return true if the interval has kills in [Start,End).
400 /// Note that the kill point is considered the end of a live range, so it is
401 /// not contained in the live range. If a live range ends at End, it won't
402 /// be counted as a kill by this method.
403 bool killedInRange(SlotIndex Start, SlotIndex End) const;
405 /// getLiveRangeContaining - Return the live range that contains the
406 /// specified index, or null if there is none.
407 const LiveRange *getLiveRangeContaining(SlotIndex Idx) const {
408 const_iterator I = FindLiveRangeContaining(Idx);
409 return I == end() ? 0 : &*I;
412 /// getLiveRangeContaining - Return the live range that contains the
413 /// specified index, or null if there is none.
414 LiveRange *getLiveRangeContaining(SlotIndex Idx) {
415 iterator I = FindLiveRangeContaining(Idx);
416 return I == end() ? 0 : &*I;
419 /// getVNInfoAt - Return the VNInfo that is live at Idx, or NULL.
420 VNInfo *getVNInfoAt(SlotIndex Idx) const {
421 const_iterator I = FindLiveRangeContaining(Idx);
422 return I == end() ? 0 : I->valno;
425 /// FindLiveRangeContaining - Return an iterator to the live range that
426 /// contains the specified index, or end() if there is none.
427 iterator FindLiveRangeContaining(SlotIndex Idx) {
428 iterator I = find(Idx);
429 return I != end() && I->start <= Idx ? I : end();
432 const_iterator FindLiveRangeContaining(SlotIndex Idx) const {
433 const_iterator I = find(Idx);
434 return I != end() && I->start <= Idx ? I : end();
437 /// findDefinedVNInfo - Find the by the specified
438 /// index (register interval) or defined
439 VNInfo *findDefinedVNInfoForRegInt(SlotIndex Idx) const;
442 /// overlaps - Return true if the intersection of the two live intervals is
444 bool overlaps(const LiveInterval& other) const {
447 return overlapsFrom(other, other.begin());
450 /// overlaps - Return true if the live interval overlaps a range specified
452 bool overlaps(SlotIndex Start, SlotIndex End) const;
454 /// overlapsFrom - Return true if the intersection of the two live intervals
455 /// is not empty. The specified iterator is a hint that we can begin
456 /// scanning the Other interval starting at I.
457 bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
459 /// addRange - Add the specified LiveRange to this interval, merging
460 /// intervals as appropriate. This returns an iterator to the inserted live
461 /// range (which may have grown since it was inserted.
462 void addRange(LiveRange LR) {
463 addRangeFrom(LR, ranges.begin());
466 /// join - Join two live intervals (this, and other) together. This applies
467 /// mappings to the value numbers in the LHS/RHS intervals as specified. If
468 /// the intervals are not joinable, this aborts.
469 void join(LiveInterval &Other,
470 const int *ValNoAssignments,
471 const int *RHSValNoAssignments,
472 SmallVector<VNInfo*, 16> &NewVNInfo,
473 MachineRegisterInfo *MRI);
475 /// isInOneLiveRange - Return true if the range specified is entirely in the
476 /// a single LiveRange of the live interval.
477 bool isInOneLiveRange(SlotIndex Start, SlotIndex End) const {
478 const_iterator r = find(Start);
479 return r != end() && r->containsRange(Start, End);
482 /// removeRange - Remove the specified range from this interval. Note that
483 /// the range must be a single LiveRange in its entirety.
484 void removeRange(SlotIndex Start, SlotIndex End,
485 bool RemoveDeadValNo = false);
487 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) {
488 removeRange(LR.start, LR.end, RemoveDeadValNo);
491 /// removeValNo - Remove all the ranges defined by the specified value#.
492 /// Also remove the value# from value# list.
493 void removeValNo(VNInfo *ValNo);
495 /// getSize - Returns the sum of sizes of all the LiveRange's.
497 unsigned getSize() const;
499 /// Returns true if the live interval is zero length, i.e. no live ranges
500 /// span instructions. It doesn't pay to spill such an interval.
501 bool isZeroLength() const {
502 for (const_iterator i = begin(), e = end(); i != e; ++i)
503 if (i->end.getPrevIndex() > i->start)
508 /// isSpillable - Can this interval be spilled?
509 bool isSpillable() const {
510 return weight != HUGE_VALF;
513 /// markNotSpillable - Mark interval as not spillable
514 void markNotSpillable() {
518 /// ComputeJoinedWeight - Set the weight of a live interval after
519 /// Other has been merged into it.
520 void ComputeJoinedWeight(const LiveInterval &Other);
522 bool operator<(const LiveInterval& other) const {
523 const SlotIndex &thisIndex = beginIndex();
524 const SlotIndex &otherIndex = other.beginIndex();
525 return (thisIndex < otherIndex ||
526 (thisIndex == otherIndex && reg < other.reg));
529 void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const;
534 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
535 void extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd);
536 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStr);
537 void markValNoForDeletion(VNInfo *V);
539 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
543 inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) {
548 /// ConnectedVNInfoEqClasses - Helper class that can divide VNInfos in a
549 /// LiveInterval into equivalence clases of connected components. A
550 /// LiveInterval that has multiple connected components can be broken into
551 /// multiple LiveIntervals.
553 /// Given a LiveInterval that may have multiple connected components, run:
555 /// unsigned numComps = ConEQ.Classify(LI);
556 /// if (numComps > 1) {
557 /// // allocate numComps-1 new LiveIntervals into LIS[1..]
558 /// ConEQ.Distribute(LIS);
561 class ConnectedVNInfoEqClasses {
564 // Map each value number to its equivalence class.
565 // The invariant is that EqClass[x] <= x.
566 // Two values are connected iff EqClass[x] == EqClass[b].
567 SmallVector<unsigned, 8> eqClass_;
569 // Note that values a and b are connected.
570 void Connect(unsigned a, unsigned b);
575 explicit ConnectedVNInfoEqClasses(LiveIntervals &lis) : lis_(lis) {}
577 /// Classify - Classify the values in LI into connected components.
578 /// Return the number of connected components.
579 unsigned Classify(const LiveInterval *LI);
581 /// getEqClass - Classify creates equivalence classes numbered 0..N. Return
582 /// the equivalence class assigned the VNI.
583 unsigned getEqClass(const VNInfo *VNI) { return eqClass_[VNI->id]; }
585 /// Distribute - Distribute values in LIV[0] into a separate LiveInterval
586 /// for each connected component. LIV must have a LiveInterval for each
587 /// connected component. The LiveIntervals in Liv[1..] must be empty.
588 void Distribute(LiveInterval *LIV[]);