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.
42 /// Care must be taken in interpreting the def index of the value. The
43 /// following rules apply:
45 /// If the isDefAccurate() method returns false then def does not contain the
46 /// index of the defining MachineInstr, or even (necessarily) to a
47 /// MachineInstr at all. In general such a def index is not meaningful
48 /// and should not be used. The exception is that, for values originally
49 /// defined by PHI instructions, after PHI elimination def will contain the
50 /// index of the MBB in which the PHI originally existed. This can be used
51 /// to insert code (spills or copies) which deals with the value, which will
52 /// be live in to the block.
60 IS_DEF_ACCURATE = 1 << 4
70 typedef BumpPtrAllocator Allocator;
72 /// The ID number of this value.
75 /// The index of the defining instruction (if isDefAccurate() returns true).
78 /// VNInfo constructor.
79 /// d is presumed to point to the actual defining instr. If it doesn't
80 /// setIsDefAccurate(false) should be called after construction.
81 VNInfo(unsigned i, SlotIndex d, MachineInstr *c)
82 : flags(IS_DEF_ACCURATE), id(i), def(d) { cr.copy = c; }
84 /// VNInfo construtor, copies values from orig, except for the value number.
85 VNInfo(unsigned i, const VNInfo &orig)
86 : flags(orig.flags), cr(orig.cr), id(i), def(orig.def)
89 /// Copy from the parameter into this VNInfo.
90 void copyFrom(VNInfo &src) {
96 /// Used for copying value number info.
97 unsigned getFlags() const { return flags; }
98 void setFlags(unsigned flags) { this->flags = flags; }
100 /// For a register interval, if this VN was definied by a copy instr
101 /// getCopy() returns a pointer to it, otherwise returns 0.
102 /// For a stack interval the behaviour of this method is undefined.
103 MachineInstr* getCopy() const { return cr.copy; }
104 /// For a register interval, set the copy member.
105 /// This method should not be called on stack intervals as it may lead to
106 /// undefined behavior.
107 void setCopy(MachineInstr *c) { cr.copy = c; }
109 /// For a stack interval, returns the reg which this stack interval was
111 /// For a register interval the behaviour of this method is undefined.
112 unsigned getReg() const { return cr.reg; }
113 /// For a stack interval, set the defining register.
114 /// This method should not be called on register intervals as it may lead
115 /// to undefined behaviour.
116 void setReg(unsigned reg) { cr.reg = reg; }
118 /// Returns true if one or more kills are PHI nodes.
119 bool hasPHIKill() const { return flags & HAS_PHI_KILL; }
120 /// Set the PHI kill flag on this value.
121 void setHasPHIKill(bool hasKill) {
123 flags |= HAS_PHI_KILL;
125 flags &= ~HAS_PHI_KILL;
128 /// Returns true if this value is re-defined by an early clobber somewhere
129 /// during the live range.
130 bool hasRedefByEC() const { return flags & REDEF_BY_EC; }
131 /// Set the "redef by early clobber" flag on this value.
132 void setHasRedefByEC(bool hasRedef) {
134 flags |= REDEF_BY_EC;
136 flags &= ~REDEF_BY_EC;
139 /// Returns true if this value is defined by a PHI instruction (or was,
140 /// PHI instrucions may have been eliminated).
141 bool isPHIDef() const { return flags & IS_PHI_DEF; }
142 /// Set the "phi def" flag on this value.
143 void setIsPHIDef(bool phiDef) {
147 flags &= ~IS_PHI_DEF;
150 /// Returns true if this value is unused.
151 bool isUnused() const { return flags & IS_UNUSED; }
152 /// Set the "is unused" flag on this value.
153 void setIsUnused(bool unused) {
160 /// Returns true if the def is accurate.
161 bool isDefAccurate() const { return flags & IS_DEF_ACCURATE; }
162 /// Set the "is def accurate" flag on this value.
163 void setIsDefAccurate(bool defAccurate) {
165 flags |= IS_DEF_ACCURATE;
167 flags &= ~IS_DEF_ACCURATE;
171 /// LiveRange structure - This represents a simple register range in the
172 /// program, with an inclusive start point and an exclusive end point.
173 /// These ranges are rendered as [start,end).
175 SlotIndex start; // Start point of the interval (inclusive)
176 SlotIndex end; // End point of the interval (exclusive)
177 VNInfo *valno; // identifier for the value contained in this interval.
179 LiveRange(SlotIndex S, SlotIndex E, VNInfo *V)
180 : start(S), end(E), valno(V) {
182 assert(S < E && "Cannot create empty or backwards range");
185 /// contains - Return true if the index is covered by this range.
187 bool contains(SlotIndex I) const {
188 return start <= I && I < end;
191 /// containsRange - Return true if the given range, [S, E), is covered by
193 bool containsRange(SlotIndex S, SlotIndex E) const {
194 assert((S < E) && "Backwards interval?");
195 return (start <= S && S < end) && (start < E && E <= end);
198 bool operator<(const LiveRange &LR) const {
199 return start < LR.start || (start == LR.start && end < LR.end);
201 bool operator==(const LiveRange &LR) const {
202 return start == LR.start && end == LR.end;
206 void print(raw_ostream &os) const;
209 LiveRange(); // DO NOT IMPLEMENT
212 template <> struct isPodLike<LiveRange> { static const bool value = true; };
214 raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR);
217 inline bool operator<(SlotIndex V, const LiveRange &LR) {
221 inline bool operator<(const LiveRange &LR, SlotIndex V) {
225 /// LiveInterval - This class represents some number of live ranges for a
226 /// register or value. This class also contains a bit of register allocator
231 typedef SmallVector<LiveRange,4> Ranges;
232 typedef SmallVector<VNInfo*,4> VNInfoList;
234 unsigned reg; // the register or stack slot of this interval
235 // if the top bits is set, it represents a stack slot.
236 float weight; // weight of this interval
237 Ranges ranges; // the ranges in which this register is live
238 VNInfoList valnos; // value#'s
251 LiveInterval(unsigned Reg, float Weight, bool IsSS = false)
252 : reg(Reg), weight(Weight) {
254 reg = reg | (1U << (sizeof(unsigned)*CHAR_BIT-1));
257 typedef Ranges::iterator iterator;
258 iterator begin() { return ranges.begin(); }
259 iterator end() { return ranges.end(); }
261 typedef Ranges::const_iterator const_iterator;
262 const_iterator begin() const { return ranges.begin(); }
263 const_iterator end() const { return ranges.end(); }
265 typedef VNInfoList::iterator vni_iterator;
266 vni_iterator vni_begin() { return valnos.begin(); }
267 vni_iterator vni_end() { return valnos.end(); }
269 typedef VNInfoList::const_iterator const_vni_iterator;
270 const_vni_iterator vni_begin() const { return valnos.begin(); }
271 const_vni_iterator vni_end() const { return valnos.end(); }
273 /// advanceTo - Advance the specified iterator to point to the LiveRange
274 /// containing the specified position, or end() if the position is past the
275 /// end of the interval. If no LiveRange contains this position, but the
276 /// position is in a hole, this method returns an iterator pointing to the
277 /// LiveRange immediately after the hole.
278 iterator advanceTo(iterator I, SlotIndex Pos) {
279 if (Pos >= endIndex())
281 while (I->end <= Pos) ++I;
290 /// isStackSlot - Return true if this is a stack slot interval.
292 bool isStackSlot() const {
293 return reg & (1U << (sizeof(unsigned)*CHAR_BIT-1));
296 /// getStackSlotIndex - Return stack slot index if this is a stack slot
298 int getStackSlotIndex() const {
299 assert(isStackSlot() && "Interval is not a stack slot interval!");
300 return reg & ~(1U << (sizeof(unsigned)*CHAR_BIT-1));
303 bool hasAtLeastOneValue() const { return !valnos.empty(); }
305 bool containsOneValue() const { return valnos.size() == 1; }
307 unsigned getNumValNums() const { return (unsigned)valnos.size(); }
309 /// getValNumInfo - Returns pointer to the specified val#.
311 inline VNInfo *getValNumInfo(unsigned ValNo) {
312 return valnos[ValNo];
314 inline const VNInfo *getValNumInfo(unsigned ValNo) const {
315 return valnos[ValNo];
318 /// getNextValue - Create a new value number and return it. MIIdx specifies
319 /// the instruction that defines the value number.
320 VNInfo *getNextValue(SlotIndex def, MachineInstr *CopyMI,
321 bool isDefAccurate, VNInfo::Allocator &VNInfoAllocator) {
323 new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), def, CopyMI);
324 VNI->setIsDefAccurate(isDefAccurate);
325 valnos.push_back(VNI);
329 /// Create a copy of the given value. The new value will be identical except
330 /// for the Value number.
331 VNInfo *createValueCopy(const VNInfo *orig,
332 VNInfo::Allocator &VNInfoAllocator) {
334 new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), *orig);
335 valnos.push_back(VNI);
339 /// RenumberValues - Renumber all values in order of appearance and remove
341 void RenumberValues();
343 /// isOnlyLROfValNo - Return true if the specified live range is the only
344 /// one defined by the its val#.
345 bool isOnlyLROfValNo(const LiveRange *LR) {
346 for (const_iterator I = begin(), E = end(); I != E; ++I) {
347 const LiveRange *Tmp = I;
348 if (Tmp != LR && Tmp->valno == LR->valno)
354 /// MergeValueNumberInto - This method is called when two value nubmers
355 /// are found to be equivalent. This eliminates V1, replacing all
356 /// LiveRanges with the V1 value number with the V2 value number. This can
357 /// cause merging of V1/V2 values numbers and compaction of the value space.
358 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2);
360 /// MergeInClobberRanges - For any live ranges that are not defined in the
361 /// current interval, but are defined in the Clobbers interval, mark them
362 /// used with an unknown definition value. Caller must pass in reference to
363 /// VNInfoAllocator since it will create a new val#.
364 void MergeInClobberRanges(LiveIntervals &li_,
365 const LiveInterval &Clobbers,
366 VNInfo::Allocator &VNInfoAllocator);
368 /// MergeInClobberRange - Same as MergeInClobberRanges except it merge in a
369 /// single LiveRange only.
370 void MergeInClobberRange(LiveIntervals &li_,
373 VNInfo::Allocator &VNInfoAllocator);
375 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
376 /// in RHS into this live interval as the specified value number.
377 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
378 /// current interval, it will replace the value numbers of the overlaped
379 /// live ranges with the specified value number.
380 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo);
382 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
383 /// in RHS into this live interval as the specified value number.
384 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
385 /// current interval, but only if the overlapping LiveRanges have the
386 /// specified value number.
387 void MergeValueInAsValue(const LiveInterval &RHS,
388 const VNInfo *RHSValNo, VNInfo *LHSValNo);
390 /// Copy - Copy the specified live interval. This copies all the fields
391 /// except for the register of the interval.
392 void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI,
393 VNInfo::Allocator &VNInfoAllocator);
395 bool empty() const { return ranges.empty(); }
397 /// beginIndex - Return the lowest numbered slot covered by interval.
398 SlotIndex beginIndex() const {
399 assert(!empty() && "Call to beginIndex() on empty interval.");
400 return ranges.front().start;
403 /// endNumber - return the maximum point of the interval of the whole,
405 SlotIndex endIndex() const {
406 assert(!empty() && "Call to endIndex() on empty interval.");
407 return ranges.back().end;
410 bool expiredAt(SlotIndex index) const {
411 return index >= endIndex();
414 bool liveAt(SlotIndex index) const;
416 // liveBeforeAndAt - Check if the interval is live at the index and the
417 // index just before it. If index is liveAt, check if it starts a new live
418 // range.If it does, then check if the previous live range ends at index-1.
419 bool liveBeforeAndAt(SlotIndex index) const;
421 /// killedAt - Return true if a live range ends at index. Note that the kill
422 /// point is not contained in the half-open live range. It is usually the
423 /// getDefIndex() slot following its last use.
424 bool killedAt(SlotIndex index) const;
426 /// killedInRange - Return true if the interval has kills in [Start,End).
427 /// Note that the kill point is considered the end of a live range, so it is
428 /// not contained in the live range. If a live range ends at End, it won't
429 /// be counted as a kill by this method.
430 bool killedInRange(SlotIndex Start, SlotIndex End) const;
432 /// getLiveRangeContaining - Return the live range that contains the
433 /// specified index, or null if there is none.
434 const LiveRange *getLiveRangeContaining(SlotIndex Idx) const {
435 const_iterator I = FindLiveRangeContaining(Idx);
436 return I == end() ? 0 : &*I;
439 /// getLiveRangeContaining - Return the live range that contains the
440 /// specified index, or null if there is none.
441 LiveRange *getLiveRangeContaining(SlotIndex Idx) {
442 iterator I = FindLiveRangeContaining(Idx);
443 return I == end() ? 0 : &*I;
446 /// getVNInfoAt - Return the VNInfo that is live at Idx, or NULL.
447 VNInfo *getVNInfoAt(SlotIndex Idx) const {
448 const_iterator I = FindLiveRangeContaining(Idx);
449 return I == end() ? 0 : I->valno;
452 /// FindLiveRangeContaining - Return an iterator to the live range that
453 /// contains the specified index, or end() if there is none.
454 const_iterator FindLiveRangeContaining(SlotIndex Idx) const;
456 /// FindLiveRangeContaining - Return an iterator to the live range that
457 /// contains the specified index, or end() if there is none.
458 iterator FindLiveRangeContaining(SlotIndex Idx);
460 /// findDefinedVNInfo - Find the by the specified
461 /// index (register interval) or defined
462 VNInfo *findDefinedVNInfoForRegInt(SlotIndex Idx) const;
464 /// findDefinedVNInfo - Find the VNInfo that's defined by the specified
465 /// register (stack inteval only).
466 VNInfo *findDefinedVNInfoForStackInt(unsigned Reg) const;
469 /// overlaps - Return true if the intersection of the two live intervals is
471 bool overlaps(const LiveInterval& other) const {
474 return overlapsFrom(other, other.begin());
477 /// overlaps - Return true if the live interval overlaps a range specified
479 bool overlaps(SlotIndex Start, SlotIndex End) const;
481 /// overlapsFrom - Return true if the intersection of the two live intervals
482 /// is not empty. The specified iterator is a hint that we can begin
483 /// scanning the Other interval starting at I.
484 bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
486 /// addRange - Add the specified LiveRange to this interval, merging
487 /// intervals as appropriate. This returns an iterator to the inserted live
488 /// range (which may have grown since it was inserted.
489 void addRange(LiveRange LR) {
490 addRangeFrom(LR, ranges.begin());
493 /// join - Join two live intervals (this, and other) together. This applies
494 /// mappings to the value numbers in the LHS/RHS intervals as specified. If
495 /// the intervals are not joinable, this aborts.
496 void join(LiveInterval &Other,
497 const int *ValNoAssignments,
498 const int *RHSValNoAssignments,
499 SmallVector<VNInfo*, 16> &NewVNInfo,
500 MachineRegisterInfo *MRI);
502 /// isInOneLiveRange - Return true if the range specified is entirely in the
503 /// a single LiveRange of the live interval.
504 bool isInOneLiveRange(SlotIndex Start, SlotIndex End);
506 /// removeRange - Remove the specified range from this interval. Note that
507 /// the range must be a single LiveRange in its entirety.
508 void removeRange(SlotIndex Start, SlotIndex End,
509 bool RemoveDeadValNo = false);
511 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) {
512 removeRange(LR.start, LR.end, RemoveDeadValNo);
515 /// removeValNo - Remove all the ranges defined by the specified value#.
516 /// Also remove the value# from value# list.
517 void removeValNo(VNInfo *ValNo);
519 /// getSize - Returns the sum of sizes of all the LiveRange's.
521 unsigned getSize() const;
523 /// Returns true if the live interval is zero length, i.e. no live ranges
524 /// span instructions. It doesn't pay to spill such an interval.
525 bool isZeroLength() const {
526 for (const_iterator i = begin(), e = end(); i != e; ++i)
527 if (i->end.getPrevIndex() > i->start)
532 /// isSpillable - Can this interval be spilled?
533 bool isSpillable() const {
534 return weight != HUGE_VALF;
537 /// markNotSpillable - Mark interval as not spillable
538 void markNotSpillable() {
542 /// ComputeJoinedWeight - Set the weight of a live interval after
543 /// Other has been merged into it.
544 void ComputeJoinedWeight(const LiveInterval &Other);
546 bool operator<(const LiveInterval& other) const {
547 const SlotIndex &thisIndex = beginIndex();
548 const SlotIndex &otherIndex = other.beginIndex();
549 return (thisIndex < otherIndex ||
550 (thisIndex == otherIndex && reg < other.reg));
553 void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const;
558 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
559 void extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd);
560 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStr);
561 void markValNoForDeletion(VNInfo *V);
563 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
567 inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) {