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/IntEqClasses.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 /// Obsolete, do not use!
104 bool hasPHIKill() const { return flags & HAS_PHI_KILL; }
105 /// Set the PHI kill flag on this value.
106 void setHasPHIKill(bool hasKill) {
108 flags |= HAS_PHI_KILL;
110 flags &= ~HAS_PHI_KILL;
113 /// Returns true if this value is re-defined by an early clobber somewhere
114 /// during the live range.
115 bool hasRedefByEC() const { return flags & REDEF_BY_EC; }
116 /// Set the "redef by early clobber" flag on this value.
117 void setHasRedefByEC(bool hasRedef) {
119 flags |= REDEF_BY_EC;
121 flags &= ~REDEF_BY_EC;
124 /// Returns true if this value is defined by a PHI instruction (or was,
125 /// PHI instrucions may have been eliminated).
126 bool isPHIDef() const { return flags & IS_PHI_DEF; }
127 /// Set the "phi def" flag on this value.
128 void setIsPHIDef(bool phiDef) {
132 flags &= ~IS_PHI_DEF;
135 /// Returns true if this value is unused.
136 bool isUnused() const { return flags & IS_UNUSED; }
137 /// Set the "is unused" flag on this value.
138 void setIsUnused(bool unused) {
146 /// LiveRange structure - This represents a simple register range in the
147 /// program, with an inclusive start point and an exclusive end point.
148 /// These ranges are rendered as [start,end).
150 SlotIndex start; // Start point of the interval (inclusive)
151 SlotIndex end; // End point of the interval (exclusive)
152 VNInfo *valno; // identifier for the value contained in this interval.
154 LiveRange(SlotIndex S, SlotIndex E, VNInfo *V)
155 : start(S), end(E), valno(V) {
157 assert(S < E && "Cannot create empty or backwards range");
160 /// contains - Return true if the index is covered by this range.
162 bool contains(SlotIndex I) const {
163 return start <= I && I < end;
166 /// containsRange - Return true if the given range, [S, E), is covered by
168 bool containsRange(SlotIndex S, SlotIndex E) const {
169 assert((S < E) && "Backwards interval?");
170 return (start <= S && S < end) && (start < E && E <= end);
173 bool operator<(const LiveRange &LR) const {
174 return start < LR.start || (start == LR.start && end < LR.end);
176 bool operator==(const LiveRange &LR) const {
177 return start == LR.start && end == LR.end;
181 void print(raw_ostream &os) const;
184 LiveRange(); // DO NOT IMPLEMENT
187 template <> struct isPodLike<LiveRange> { static const bool value = true; };
189 raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR);
192 inline bool operator<(SlotIndex V, const LiveRange &LR) {
196 inline bool operator<(const LiveRange &LR, SlotIndex V) {
200 /// LiveInterval - This class represents some number of live ranges for a
201 /// register or value. This class also contains a bit of register allocator
206 typedef SmallVector<LiveRange,4> Ranges;
207 typedef SmallVector<VNInfo*,4> VNInfoList;
209 const unsigned reg; // the register or stack slot of this interval.
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)
226 : reg(Reg), weight(Weight) {}
228 typedef Ranges::iterator iterator;
229 iterator begin() { return ranges.begin(); }
230 iterator end() { return ranges.end(); }
232 typedef Ranges::const_iterator const_iterator;
233 const_iterator begin() const { return ranges.begin(); }
234 const_iterator end() const { return ranges.end(); }
236 typedef VNInfoList::iterator vni_iterator;
237 vni_iterator vni_begin() { return valnos.begin(); }
238 vni_iterator vni_end() { return valnos.end(); }
240 typedef VNInfoList::const_iterator const_vni_iterator;
241 const_vni_iterator vni_begin() const { return valnos.begin(); }
242 const_vni_iterator vni_end() const { return valnos.end(); }
244 /// advanceTo - Advance the specified iterator to point to the LiveRange
245 /// containing the specified position, or end() if the position is past the
246 /// end of the interval. If no LiveRange contains this position, but the
247 /// position is in a hole, this method returns an iterator pointing to the
248 /// LiveRange immediately after the hole.
249 iterator advanceTo(iterator I, SlotIndex Pos) {
251 if (Pos >= endIndex())
253 while (I->end <= Pos) ++I;
257 /// find - Return an iterator pointing to the first range that ends after
258 /// Pos, or end(). This is the same as advanceTo(begin(), Pos), but faster
259 /// when searching large intervals.
261 /// If Pos is contained in a LiveRange, that range is returned.
262 /// If Pos is in a hole, the following LiveRange is returned.
263 /// If Pos is beyond endIndex, end() is returned.
264 iterator find(SlotIndex Pos);
266 const_iterator find(SlotIndex Pos) const {
267 return const_cast<LiveInterval*>(this)->find(Pos);
275 bool hasAtLeastOneValue() const { return !valnos.empty(); }
277 bool containsOneValue() const { return valnos.size() == 1; }
279 unsigned getNumValNums() const { return (unsigned)valnos.size(); }
281 /// getValNumInfo - Returns pointer to the specified val#.
283 inline VNInfo *getValNumInfo(unsigned ValNo) {
284 return valnos[ValNo];
286 inline const VNInfo *getValNumInfo(unsigned ValNo) const {
287 return valnos[ValNo];
290 /// containsValue - Returns true if VNI belongs to this interval.
291 bool containsValue(const VNInfo *VNI) const {
292 return VNI && VNI->id < getNumValNums() && VNI == getValNumInfo(VNI->id);
295 /// getNextValue - Create a new value number and return it. MIIdx specifies
296 /// the instruction that defines the value number.
297 VNInfo *getNextValue(SlotIndex def, MachineInstr *CopyMI,
298 VNInfo::Allocator &VNInfoAllocator) {
300 new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), def, CopyMI);
301 valnos.push_back(VNI);
305 /// Create a copy of the given value. The new value will be identical except
306 /// for the Value number.
307 VNInfo *createValueCopy(const VNInfo *orig,
308 VNInfo::Allocator &VNInfoAllocator) {
310 new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), *orig);
311 valnos.push_back(VNI);
315 /// RenumberValues - Renumber all values in order of appearance and remove
317 void RenumberValues(LiveIntervals &lis);
319 /// isOnlyLROfValNo - Return true if the specified live range is the only
320 /// one defined by the its val#.
321 bool isOnlyLROfValNo(const LiveRange *LR) {
322 for (const_iterator I = begin(), E = end(); I != E; ++I) {
323 const LiveRange *Tmp = I;
324 if (Tmp != LR && Tmp->valno == LR->valno)
330 /// MergeValueNumberInto - This method is called when two value nubmers
331 /// are found to be equivalent. This eliminates V1, replacing all
332 /// LiveRanges with the V1 value number with the V2 value number. This can
333 /// cause merging of V1/V2 values numbers and compaction of the value space.
334 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2);
336 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
337 /// in RHS into this live interval as the specified value number.
338 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
339 /// current interval, it will replace the value numbers of the overlaped
340 /// live ranges with the specified value number.
341 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo);
343 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
344 /// in RHS into this live interval as the specified value number.
345 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
346 /// current interval, but only if the overlapping LiveRanges have the
347 /// specified value number.
348 void MergeValueInAsValue(const LiveInterval &RHS,
349 const VNInfo *RHSValNo, VNInfo *LHSValNo);
351 /// Copy - Copy the specified live interval. This copies all the fields
352 /// except for the register of the interval.
353 void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI,
354 VNInfo::Allocator &VNInfoAllocator);
356 bool empty() const { return ranges.empty(); }
358 /// beginIndex - Return the lowest numbered slot covered by interval.
359 SlotIndex beginIndex() const {
360 assert(!empty() && "Call to beginIndex() on empty interval.");
361 return ranges.front().start;
364 /// endNumber - return the maximum point of the interval of the whole,
366 SlotIndex endIndex() const {
367 assert(!empty() && "Call to endIndex() on empty interval.");
368 return ranges.back().end;
371 bool expiredAt(SlotIndex index) const {
372 return index >= endIndex();
375 bool liveAt(SlotIndex index) const {
376 const_iterator r = find(index);
377 return r != end() && r->start <= index;
380 /// killedAt - Return true if a live range ends at index. Note that the kill
381 /// point is not contained in the half-open live range. It is usually the
382 /// getDefIndex() slot following its last use.
383 bool killedAt(SlotIndex index) const {
384 const_iterator r = find(index.getUseIndex());
385 return r != end() && r->end == index;
388 /// killedInRange - Return true if the interval has kills in [Start,End).
389 /// Note that the kill point is considered the end of a live range, so it is
390 /// not contained in the live range. If a live range ends at End, it won't
391 /// be counted as a kill by this method.
392 bool killedInRange(SlotIndex Start, SlotIndex End) const;
394 /// getLiveRangeContaining - Return the live range that contains the
395 /// specified index, or null if there is none.
396 const LiveRange *getLiveRangeContaining(SlotIndex Idx) const {
397 const_iterator I = FindLiveRangeContaining(Idx);
398 return I == end() ? 0 : &*I;
401 /// getLiveRangeContaining - Return the live range that contains the
402 /// specified index, or null if there is none.
403 LiveRange *getLiveRangeContaining(SlotIndex Idx) {
404 iterator I = FindLiveRangeContaining(Idx);
405 return I == end() ? 0 : &*I;
408 /// getVNInfoAt - Return the VNInfo that is live at Idx, or NULL.
409 VNInfo *getVNInfoAt(SlotIndex Idx) const {
410 const_iterator I = FindLiveRangeContaining(Idx);
411 return I == end() ? 0 : I->valno;
414 /// getVNInfoBefore - Return the VNInfo that is live up to but not
415 /// necessarilly including Idx, or NULL. Use this to find the reaching def
416 /// used by an instruction at this SlotIndex position.
417 VNInfo *getVNInfoBefore(SlotIndex Idx) const {
418 const_iterator I = FindLiveRangeContaining(Idx.getPrevSlot());
419 return I == end() ? 0 : I->valno;
422 /// FindLiveRangeContaining - Return an iterator to the live range that
423 /// contains the specified index, or end() if there is none.
424 iterator FindLiveRangeContaining(SlotIndex Idx) {
425 iterator I = find(Idx);
426 return I != end() && I->start <= Idx ? I : end();
429 const_iterator FindLiveRangeContaining(SlotIndex Idx) const {
430 const_iterator I = find(Idx);
431 return I != end() && I->start <= Idx ? I : end();
434 /// findDefinedVNInfo - Find the by the specified
435 /// index (register interval) or defined
436 VNInfo *findDefinedVNInfoForRegInt(SlotIndex Idx) const;
439 /// overlaps - Return true if the intersection of the two live intervals is
441 bool overlaps(const LiveInterval& other) const {
444 return overlapsFrom(other, other.begin());
447 /// overlaps - Return true if the live interval overlaps a range specified
449 bool overlaps(SlotIndex Start, SlotIndex End) const;
451 /// overlapsFrom - Return true if the intersection of the two live intervals
452 /// is not empty. The specified iterator is a hint that we can begin
453 /// scanning the Other interval starting at I.
454 bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
456 /// addRange - Add the specified LiveRange to this interval, merging
457 /// intervals as appropriate. This returns an iterator to the inserted live
458 /// range (which may have grown since it was inserted.
459 void addRange(LiveRange LR) {
460 addRangeFrom(LR, ranges.begin());
463 /// extendInBlock - If this interval is live before Kill in the basic block
464 /// that starts at StartIdx, extend it to be live up to Kill, and return
465 /// the value. If there is no live range before Kill, return NULL.
466 VNInfo *extendInBlock(SlotIndex StartIdx, SlotIndex Kill);
468 /// join - Join two live intervals (this, and other) together. This applies
469 /// mappings to the value numbers in the LHS/RHS intervals as specified. If
470 /// the intervals are not joinable, this aborts.
471 void join(LiveInterval &Other,
472 const int *ValNoAssignments,
473 const int *RHSValNoAssignments,
474 SmallVector<VNInfo*, 16> &NewVNInfo,
475 MachineRegisterInfo *MRI);
477 /// isInOneLiveRange - Return true if the range specified is entirely in the
478 /// a single LiveRange of the live interval.
479 bool isInOneLiveRange(SlotIndex Start, SlotIndex End) const {
480 const_iterator r = find(Start);
481 return r != end() && r->containsRange(Start, End);
484 /// removeRange - Remove the specified range from this interval. Note that
485 /// the range must be a single LiveRange in its entirety.
486 void removeRange(SlotIndex Start, SlotIndex End,
487 bool RemoveDeadValNo = false);
489 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) {
490 removeRange(LR.start, LR.end, RemoveDeadValNo);
493 /// removeValNo - Remove all the ranges defined by the specified value#.
494 /// Also remove the value# from value# list.
495 void removeValNo(VNInfo *ValNo);
497 /// getSize - Returns the sum of sizes of all the LiveRange's.
499 unsigned getSize() const;
501 /// Returns true if the live interval is zero length, i.e. no live ranges
502 /// span instructions. It doesn't pay to spill such an interval.
503 bool isZeroLength(SlotIndexes *Indexes) const {
504 for (const_iterator i = begin(), e = end(); i != e; ++i)
505 if (Indexes->getNextNonNullIndex(i->start).getBaseIndex() <
506 i->end.getBaseIndex())
511 /// isSpillable - Can this interval be spilled?
512 bool isSpillable() const {
513 return weight != HUGE_VALF;
516 /// markNotSpillable - Mark interval as not spillable
517 void markNotSpillable() {
521 /// ComputeJoinedWeight - Set the weight of a live interval after
522 /// Other has been merged into it.
523 void ComputeJoinedWeight(const LiveInterval &Other);
525 bool operator<(const LiveInterval& other) const {
526 const SlotIndex &thisIndex = beginIndex();
527 const SlotIndex &otherIndex = other.beginIndex();
528 return (thisIndex < otherIndex ||
529 (thisIndex == otherIndex && reg < other.reg));
532 void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const;
537 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
538 void extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd);
539 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStr);
540 void markValNoForDeletion(VNInfo *V);
542 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
546 inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) {
551 /// ConnectedVNInfoEqClasses - Helper class that can divide VNInfos in a
552 /// LiveInterval into equivalence clases of connected components. A
553 /// LiveInterval that has multiple connected components can be broken into
554 /// multiple LiveIntervals.
556 /// Given a LiveInterval that may have multiple connected components, run:
558 /// unsigned numComps = ConEQ.Classify(LI);
559 /// if (numComps > 1) {
560 /// // allocate numComps-1 new LiveIntervals into LIS[1..]
561 /// ConEQ.Distribute(LIS);
564 class ConnectedVNInfoEqClasses {
566 IntEqClasses EqClass;
568 // Note that values a and b are connected.
569 void Connect(unsigned a, unsigned b);
574 explicit ConnectedVNInfoEqClasses(LiveIntervals &lis) : LIS(lis) {}
576 /// Classify - Classify the values in LI into connected components.
577 /// Return the number of connected components.
578 unsigned Classify(const LiveInterval *LI);
580 /// getEqClass - Classify creates equivalence classes numbered 0..N. Return
581 /// the equivalence class assigned the VNI.
582 unsigned getEqClass(const VNInfo *VNI) const { return EqClass[VNI->id]; }
584 /// Distribute - Distribute values in LIV[0] into a separate LiveInterval
585 /// for each connected component. LIV must have a LiveInterval for each
586 /// connected component. The LiveIntervals in Liv[1..] must be empty.
587 /// Instructions using LIV[0] are rewritten.
588 void Distribute(LiveInterval *LIV[], MachineRegisterInfo &MRI);