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 SpecificBumpPtrAllocator<VNInfo> Allocator;
71 typedef SmallVector<SlotIndex, 4> KillSet;
73 /// The ID number of this value.
76 /// The index of the defining instruction (if isDefAccurate() returns true).
82 VNInfo(LiveIntervals &li_)
83 : defflags(IS_UNUSED), id(~1U) { cr.copy = 0; }
86 /// VNInfo constructor.
87 /// d is presumed to point to the actual defining instr. If it doesn't
88 /// setIsDefAccurate(false) should be called after construction.
89 VNInfo(unsigned i, SlotIndex d, MachineInstr *c)
90 : flags(IS_DEF_ACCURATE), id(i), def(d) { cr.copy = c; }
92 /// VNInfo construtor, copies values from orig, except for the value number.
93 VNInfo(unsigned i, const VNInfo &orig)
94 : flags(orig.flags), cr(orig.cr), id(i), def(orig.def), kills(orig.kills)
97 /// Copy from the parameter into this VNInfo.
98 void copyFrom(VNInfo &src) {
105 /// Used for copying value number info.
106 unsigned getFlags() const { return flags; }
107 void setFlags(unsigned flags) { this->flags = flags; }
109 /// For a register interval, if this VN was definied by a copy instr
110 /// getCopy() returns a pointer to it, otherwise returns 0.
111 /// For a stack interval the behaviour of this method is undefined.
112 MachineInstr* getCopy() const { return cr.copy; }
113 /// For a register interval, set the copy member.
114 /// This method should not be called on stack intervals as it may lead to
115 /// undefined behavior.
116 void setCopy(MachineInstr *c) { cr.copy = c; }
118 /// For a stack interval, returns the reg which this stack interval was
120 /// For a register interval the behaviour of this method is undefined.
121 unsigned getReg() const { return cr.reg; }
122 /// For a stack interval, set the defining register.
123 /// This method should not be called on register intervals as it may lead
124 /// to undefined behaviour.
125 void setReg(unsigned reg) { cr.reg = reg; }
127 /// Returns true if one or more kills are PHI nodes.
128 bool hasPHIKill() const { return flags & HAS_PHI_KILL; }
129 /// Set the PHI kill flag on this value.
130 void setHasPHIKill(bool hasKill) {
132 flags |= HAS_PHI_KILL;
134 flags &= ~HAS_PHI_KILL;
137 /// Returns true if this value is re-defined by an early clobber somewhere
138 /// during the live range.
139 bool hasRedefByEC() const { return flags & REDEF_BY_EC; }
140 /// Set the "redef by early clobber" flag on this value.
141 void setHasRedefByEC(bool hasRedef) {
143 flags |= REDEF_BY_EC;
145 flags &= ~REDEF_BY_EC;
148 /// Returns true if this value is defined by a PHI instruction (or was,
149 /// PHI instrucions may have been eliminated).
150 bool isPHIDef() const { return flags & IS_PHI_DEF; }
151 /// Set the "phi def" flag on this value.
152 void setIsPHIDef(bool phiDef) {
156 flags &= ~IS_PHI_DEF;
159 /// Returns true if this value is unused.
160 bool isUnused() const { return flags & IS_UNUSED; }
161 /// Set the "is unused" flag on this value.
162 void setIsUnused(bool unused) {
169 /// Returns true if the def is accurate.
170 bool isDefAccurate() const { return flags & IS_DEF_ACCURATE; }
171 /// Set the "is def accurate" flag on this value.
172 void setIsDefAccurate(bool defAccurate) {
174 flags |= IS_DEF_ACCURATE;
176 flags &= ~IS_DEF_ACCURATE;
179 /// Returns true if the given index is a kill of this value.
180 bool isKill(SlotIndex k) const {
181 KillSet::const_iterator
182 i = std::lower_bound(kills.begin(), kills.end(), k);
183 return (i != kills.end() && *i == k);
186 /// addKill - Add a kill instruction index to the specified value
188 void addKill(SlotIndex k) {
193 i = std::lower_bound(kills.begin(), kills.end(), k);
198 /// Remove the specified kill index from this value's kills list.
199 /// Returns true if the value was present, otherwise returns false.
200 bool removeKill(SlotIndex k) {
201 KillSet::iterator i = std::lower_bound(kills.begin(), kills.end(), k);
202 if (i != kills.end() && *i == k) {
209 /// Remove all kills in the range [s, e).
210 void removeKills(SlotIndex s, SlotIndex e) {
212 si = std::lower_bound(kills.begin(), kills.end(), s),
213 se = std::upper_bound(kills.begin(), kills.end(), e);
220 /// LiveRange structure - This represents a simple register range in the
221 /// program, with an inclusive start point and an exclusive end point.
222 /// These ranges are rendered as [start,end).
224 SlotIndex start; // Start point of the interval (inclusive)
225 SlotIndex end; // End point of the interval (exclusive)
226 VNInfo *valno; // identifier for the value contained in this interval.
228 LiveRange(SlotIndex S, SlotIndex E, VNInfo *V)
229 : start(S), end(E), valno(V) {
231 assert(S < E && "Cannot create empty or backwards range");
234 /// contains - Return true if the index is covered by this range.
236 bool contains(SlotIndex I) const {
237 return start <= I && I < end;
240 /// containsRange - Return true if the given range, [S, E), is covered by
242 bool containsRange(SlotIndex S, SlotIndex E) const {
243 assert((S < E) && "Backwards interval?");
244 return (start <= S && S < end) && (start < E && E <= end);
247 bool operator<(const LiveRange &LR) const {
248 return start < LR.start || (start == LR.start && end < LR.end);
250 bool operator==(const LiveRange &LR) const {
251 return start == LR.start && end == LR.end;
255 void print(raw_ostream &os) const;
258 LiveRange(); // DO NOT IMPLEMENT
261 template <> struct isPodLike<LiveRange> { static const bool value = true; };
263 raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR);
266 inline bool operator<(SlotIndex V, const LiveRange &LR) {
270 inline bool operator<(const LiveRange &LR, SlotIndex V) {
274 /// LiveInterval - This class represents some number of live ranges for a
275 /// register or value. This class also contains a bit of register allocator
280 typedef SmallVector<LiveRange,4> Ranges;
281 typedef SmallVector<VNInfo*,4> VNInfoList;
283 unsigned reg; // the register or stack slot of this interval
284 // if the top bits is set, it represents a stack slot.
285 float weight; // weight of this interval
286 Ranges ranges; // the ranges in which this register is live
287 VNInfoList valnos; // value#'s
300 LiveInterval(unsigned Reg, float Weight, bool IsSS = false)
301 : reg(Reg), weight(Weight) {
303 reg = reg | (1U << (sizeof(unsigned)*CHAR_BIT-1));
306 typedef Ranges::iterator iterator;
307 iterator begin() { return ranges.begin(); }
308 iterator end() { return ranges.end(); }
310 typedef Ranges::const_iterator const_iterator;
311 const_iterator begin() const { return ranges.begin(); }
312 const_iterator end() const { return ranges.end(); }
314 typedef VNInfoList::iterator vni_iterator;
315 vni_iterator vni_begin() { return valnos.begin(); }
316 vni_iterator vni_end() { return valnos.end(); }
318 typedef VNInfoList::const_iterator const_vni_iterator;
319 const_vni_iterator vni_begin() const { return valnos.begin(); }
320 const_vni_iterator vni_end() const { return valnos.end(); }
322 /// advanceTo - Advance the specified iterator to point to the LiveRange
323 /// containing the specified position, or end() if the position is past the
324 /// end of the interval. If no LiveRange contains this position, but the
325 /// position is in a hole, this method returns an iterator pointing to the
326 /// LiveRange immediately after the hole.
327 iterator advanceTo(iterator I, SlotIndex Pos) {
328 if (Pos >= endIndex())
330 while (I->end <= Pos) ++I;
339 /// isStackSlot - Return true if this is a stack slot interval.
341 bool isStackSlot() const {
342 return reg & (1U << (sizeof(unsigned)*CHAR_BIT-1));
345 /// getStackSlotIndex - Return stack slot index if this is a stack slot
347 int getStackSlotIndex() const {
348 assert(isStackSlot() && "Interval is not a stack slot interval!");
349 return reg & ~(1U << (sizeof(unsigned)*CHAR_BIT-1));
352 bool hasAtLeastOneValue() const { return !valnos.empty(); }
354 bool containsOneValue() const { return valnos.size() == 1; }
356 unsigned getNumValNums() const { return (unsigned)valnos.size(); }
358 /// getValNumInfo - Returns pointer to the specified val#.
360 inline VNInfo *getValNumInfo(unsigned ValNo) {
361 return valnos[ValNo];
363 inline const VNInfo *getValNumInfo(unsigned ValNo) const {
364 return valnos[ValNo];
367 /// getNextValue - Create a new value number and return it. MIIdx specifies
368 /// the instruction that defines the value number.
369 VNInfo *getNextValue(SlotIndex def, MachineInstr *CopyMI,
370 bool isDefAccurate, VNInfo::Allocator &VNInfoAllocator) {
371 VNInfo *VNI = VNInfoAllocator.Allocate();
372 new (VNI) VNInfo((unsigned)valnos.size(), def, CopyMI);
373 VNI->setIsDefAccurate(isDefAccurate);
374 valnos.push_back(VNI);
378 /// Create a copy of the given value. The new value will be identical except
379 /// for the Value number.
380 VNInfo *createValueCopy(const VNInfo *orig,
381 VNInfo::Allocator &VNInfoAllocator) {
382 VNInfo *VNI = VNInfoAllocator.Allocate();
383 new (VNI) VNInfo((unsigned)valnos.size(), *orig);
384 valnos.push_back(VNI);
388 /// addKills - Add a number of kills into the VNInfo kill vector. If this
389 /// interval is live at a kill point, then the kill is not added.
390 void addKills(VNInfo *VNI, const VNInfo::KillSet &kills) {
391 for (unsigned i = 0, e = static_cast<unsigned>(kills.size());
393 if (!liveBeforeAndAt(kills[i])) {
394 VNI->addKill(kills[i]);
399 /// isOnlyLROfValNo - Return true if the specified live range is the only
400 /// one defined by the its val#.
401 bool isOnlyLROfValNo(const LiveRange *LR) {
402 for (const_iterator I = begin(), E = end(); I != E; ++I) {
403 const LiveRange *Tmp = I;
404 if (Tmp != LR && Tmp->valno == LR->valno)
410 /// MergeValueNumberInto - This method is called when two value nubmers
411 /// are found to be equivalent. This eliminates V1, replacing all
412 /// LiveRanges with the V1 value number with the V2 value number. This can
413 /// cause merging of V1/V2 values numbers and compaction of the value space.
414 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2);
416 /// MergeInClobberRanges - For any live ranges that are not defined in the
417 /// current interval, but are defined in the Clobbers interval, mark them
418 /// used with an unknown definition value. Caller must pass in reference to
419 /// VNInfoAllocator since it will create a new val#.
420 void MergeInClobberRanges(LiveIntervals &li_,
421 const LiveInterval &Clobbers,
422 VNInfo::Allocator &VNInfoAllocator);
424 /// MergeInClobberRange - Same as MergeInClobberRanges except it merge in a
425 /// single LiveRange only.
426 void MergeInClobberRange(LiveIntervals &li_,
429 VNInfo::Allocator &VNInfoAllocator);
431 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
432 /// in RHS into this live interval as the specified value number.
433 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
434 /// current interval, it will replace the value numbers of the overlaped
435 /// live ranges with the specified value number.
436 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo);
438 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
439 /// in RHS into this live interval as the specified value number.
440 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
441 /// current interval, but only if the overlapping LiveRanges have the
442 /// specified value number.
443 void MergeValueInAsValue(const LiveInterval &RHS,
444 const VNInfo *RHSValNo, VNInfo *LHSValNo);
446 /// Copy - Copy the specified live interval. This copies all the fields
447 /// except for the register of the interval.
448 void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI,
449 VNInfo::Allocator &VNInfoAllocator);
451 bool empty() const { return ranges.empty(); }
453 /// beginIndex - Return the lowest numbered slot covered by interval.
454 SlotIndex beginIndex() const {
455 assert(!empty() && "Call to beginIndex() on empty interval.");
456 return ranges.front().start;
459 /// endNumber - return the maximum point of the interval of the whole,
461 SlotIndex endIndex() const {
462 assert(!empty() && "Call to endIndex() on empty interval.");
463 return ranges.back().end;
466 bool expiredAt(SlotIndex index) const {
467 return index >= endIndex();
470 bool liveAt(SlotIndex index) const;
472 // liveBeforeAndAt - Check if the interval is live at the index and the
473 // index just before it. If index is liveAt, check if it starts a new live
474 // range.If it does, then check if the previous live range ends at index-1.
475 bool liveBeforeAndAt(SlotIndex index) const;
477 /// getLiveRangeContaining - Return the live range that contains the
478 /// specified index, or null if there is none.
479 const LiveRange *getLiveRangeContaining(SlotIndex Idx) const {
480 const_iterator I = FindLiveRangeContaining(Idx);
481 return I == end() ? 0 : &*I;
484 /// getLiveRangeContaining - Return the live range that contains the
485 /// specified index, or null if there is none.
486 LiveRange *getLiveRangeContaining(SlotIndex Idx) {
487 iterator I = FindLiveRangeContaining(Idx);
488 return I == end() ? 0 : &*I;
491 /// FindLiveRangeContaining - Return an iterator to the live range that
492 /// contains the specified index, or end() if there is none.
493 const_iterator FindLiveRangeContaining(SlotIndex Idx) const;
495 /// FindLiveRangeContaining - Return an iterator to the live range that
496 /// contains the specified index, or end() if there is none.
497 iterator FindLiveRangeContaining(SlotIndex Idx);
499 /// findDefinedVNInfo - Find the by the specified
500 /// index (register interval) or defined
501 VNInfo *findDefinedVNInfoForRegInt(SlotIndex Idx) const;
503 /// findDefinedVNInfo - Find the VNInfo that's defined by the specified
504 /// register (stack inteval only).
505 VNInfo *findDefinedVNInfoForStackInt(unsigned Reg) const;
508 /// overlaps - Return true if the intersection of the two live intervals is
510 bool overlaps(const LiveInterval& other) const {
511 return overlapsFrom(other, other.begin());
514 /// overlaps - Return true if the live interval overlaps a range specified
516 bool overlaps(SlotIndex Start, SlotIndex End) const;
518 /// overlapsFrom - Return true if the intersection of the two live intervals
519 /// is not empty. The specified iterator is a hint that we can begin
520 /// scanning the Other interval starting at I.
521 bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
523 /// addRange - Add the specified LiveRange to this interval, merging
524 /// intervals as appropriate. This returns an iterator to the inserted live
525 /// range (which may have grown since it was inserted.
526 void addRange(LiveRange LR) {
527 addRangeFrom(LR, ranges.begin());
530 /// join - Join two live intervals (this, and other) together. This applies
531 /// mappings to the value numbers in the LHS/RHS intervals as specified. If
532 /// the intervals are not joinable, this aborts.
533 void join(LiveInterval &Other,
534 const int *ValNoAssignments,
535 const int *RHSValNoAssignments,
536 SmallVector<VNInfo*, 16> &NewVNInfo,
537 MachineRegisterInfo *MRI);
539 /// isInOneLiveRange - Return true if the range specified is entirely in the
540 /// a single LiveRange of the live interval.
541 bool isInOneLiveRange(SlotIndex Start, SlotIndex End);
543 /// removeRange - Remove the specified range from this interval. Note that
544 /// the range must be a single LiveRange in its entirety.
545 void removeRange(SlotIndex Start, SlotIndex End,
546 bool RemoveDeadValNo = false);
548 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) {
549 removeRange(LR.start, LR.end, RemoveDeadValNo);
552 /// removeValNo - Remove all the ranges defined by the specified value#.
553 /// Also remove the value# from value# list.
554 void removeValNo(VNInfo *ValNo);
556 /// getSize - Returns the sum of sizes of all the LiveRange's.
558 unsigned getSize() const;
560 /// isSpillable - Can this interval be spilled?
561 bool isSpillable() const {
562 return weight != HUGE_VALF;
565 /// markNotSpillable - Mark interval as not spillable
566 void markNotSpillable() {
570 /// ComputeJoinedWeight - Set the weight of a live interval after
571 /// Other has been merged into it.
572 void ComputeJoinedWeight(const LiveInterval &Other);
574 bool operator<(const LiveInterval& other) const {
575 const SlotIndex &thisIndex = beginIndex();
576 const SlotIndex &otherIndex = other.beginIndex();
577 return (thisIndex < otherIndex ||
578 (thisIndex == otherIndex && reg < other.reg));
581 void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const;
586 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
587 void extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd);
588 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStr);
590 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
594 inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) {