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"
33 class MachineRegisterInfo;
34 class TargetRegisterInfo;
37 /// VNInfo - Value Number Information.
38 /// This class holds information about a machine level values, including
39 /// definition and use points.
41 /// Care must be taken in interpreting the def index of the value. The
42 /// following rules apply:
44 /// If the isDefAccurate() method returns false then def does not contain the
45 /// index of the defining MachineInstr, or even (necessarily) to a
46 /// MachineInstr at all. In general such a def index is not meaningful
47 /// and should not be used. The exception is that, for values originally
48 /// defined by PHI instructions, after PHI elimination def will contain the
49 /// index of the MBB in which the PHI originally existed. This can be used
50 /// to insert code (spills or copies) which deals with the value, which will
51 /// be live in to the block.
60 IS_DEF_ACCURATE = 1 << 4
70 /// Holds information about individual kills.
73 unsigned killIdx : 31;
75 KillInfo(bool isPHIKill, unsigned killIdx)
76 : isPHIKill(isPHIKill), killIdx(killIdx) {
78 assert(killIdx != 0 && "Zero kill indices are no longer permitted.");
83 typedef SmallVector<KillInfo, 4> KillSet;
85 /// The ID number of this value.
88 /// The index of the defining instruction (if isDefAccurate() returns true).
94 : flags(IS_UNUSED), id(~1U), def(0) { cr.copy = 0; }
96 /// VNInfo constructor.
97 /// d is presumed to point to the actual defining instr. If it doesn't
98 /// setIsDefAccurate(false) should be called after construction.
99 VNInfo(unsigned i, unsigned d, MachineInstr *c)
100 : flags(IS_DEF_ACCURATE), id(i), def(d) { cr.copy = c; }
102 /// VNInfo construtor, copies values from orig, except for the value number.
103 VNInfo(unsigned i, const VNInfo &orig)
104 : flags(orig.flags), cr(orig.cr), id(i), def(orig.def), kills(orig.kills)
107 /// Copy from the parameter into this VNInfo.
108 void copyFrom(VNInfo &src) {
115 /// Used for copying value number info.
116 unsigned getFlags() const { return flags; }
117 void setFlags(unsigned flags) { this->flags = flags; }
119 /// For a register interval, if this VN was definied by a copy instr
120 /// getCopy() returns a pointer to it, otherwise returns 0.
121 /// For a stack interval the behaviour of this method is undefined.
122 MachineInstr* getCopy() const { return cr.copy; }
123 /// For a register interval, set the copy member.
124 /// This method should not be called on stack intervals as it may lead to
125 /// undefined behavior.
126 void setCopy(MachineInstr *c) { cr.copy = c; }
128 /// For a stack interval, returns the reg which this stack interval was
130 /// For a register interval the behaviour of this method is undefined.
131 unsigned getReg() const { return cr.reg; }
132 /// For a stack interval, set the defining register.
133 /// This method should not be called on register intervals as it may lead
134 /// to undefined behaviour.
135 void setReg(unsigned reg) { cr.reg = reg; }
137 /// Returns true if one or more kills are PHI nodes.
138 bool hasPHIKill() const { return flags & HAS_PHI_KILL; }
139 void setHasPHIKill(bool hasKill) {
141 flags |= HAS_PHI_KILL;
143 flags &= ~HAS_PHI_KILL;
146 /// Returns true if this value is re-defined by an early clobber somewhere
147 /// during the live range.
148 bool hasRedefByEC() const { return flags & REDEF_BY_EC; }
149 void setHasRedefByEC(bool hasRedef) {
151 flags |= REDEF_BY_EC;
153 flags &= ~REDEF_BY_EC;
156 /// Returns true if this value is defined by a PHI instruction (or was,
157 /// PHI instrucions may have been eliminated).
158 bool isPHIDef() const { return flags & IS_PHI_DEF; }
159 void setIsPHIDef(bool phiDef) {
163 flags &= ~IS_PHI_DEF;
166 /// Returns true if this value is unused.
167 bool isUnused() const { return flags & IS_UNUSED; }
168 void setIsUnused(bool unused) {
175 /// Returns true if the def is accurate.
176 bool isDefAccurate() const { return flags & IS_DEF_ACCURATE; }
177 void setIsDefAccurate(bool defAccurate) {
179 flags |= IS_DEF_ACCURATE;
181 flags &= ~IS_DEF_ACCURATE;
186 inline bool operator<(const VNInfo::KillInfo &k1, const VNInfo::KillInfo &k2) {
187 return k1.killIdx < k2.killIdx;
190 inline bool operator<(const VNInfo::KillInfo &k, unsigned idx) {
191 return k.killIdx < idx;
194 inline bool operator<(unsigned idx, const VNInfo::KillInfo &k) {
195 return idx < k.killIdx;
198 /// LiveRange structure - This represents a simple register range in the
199 /// program, with an inclusive start point and an exclusive end point.
200 /// These ranges are rendered as [start,end).
202 unsigned start; // Start point of the interval (inclusive)
203 unsigned end; // End point of the interval (exclusive)
204 VNInfo *valno; // identifier for the value contained in this interval.
206 LiveRange(unsigned S, unsigned E, VNInfo *V) : start(S), end(E), valno(V) {
207 assert(S < E && "Cannot create empty or backwards range");
210 /// contains - Return true if the index is covered by this range.
212 bool contains(unsigned I) const {
213 return start <= I && I < end;
216 bool operator<(const LiveRange &LR) const {
217 return start < LR.start || (start == LR.start && end < LR.end);
219 bool operator==(const LiveRange &LR) const {
220 return start == LR.start && end == LR.end;
224 void print(std::ostream &os) const;
225 void print(std::ostream *os) const { if (os) print(*os); }
226 void print(raw_ostream &os) const;
227 void print(raw_ostream *os) const { if (os) print(*os); }
230 LiveRange(); // DO NOT IMPLEMENT
233 std::ostream& operator<<(std::ostream& os, const LiveRange &LR);
234 raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR);
237 inline bool operator<(unsigned V, const LiveRange &LR) {
241 inline bool operator<(const LiveRange &LR, unsigned V) {
245 /// LiveInterval - This class represents some number of live ranges for a
246 /// register or value. This class also contains a bit of register allocator
251 typedef SmallVector<LiveRange,4> Ranges;
252 typedef SmallVector<VNInfo*,4> VNInfoList;
254 unsigned reg; // the register or stack slot of this interval
255 // if the top bits is set, it represents a stack slot.
256 float weight; // weight of this interval
257 Ranges ranges; // the ranges in which this register is live
258 VNInfoList valnos; // value#'s
269 static unsigned scale(unsigned slot, unsigned factor) {
270 unsigned index = slot / NUM,
272 assert(index <= ~0U / (factor * NUM) &&
273 "Rescaled interval would overflow");
274 return index * NUM * factor + offset;
279 LiveInterval(unsigned Reg, float Weight, bool IsSS = false)
280 : reg(Reg), weight(Weight) {
282 reg = reg | (1U << (sizeof(unsigned)*CHAR_BIT-1));
285 typedef Ranges::iterator iterator;
286 iterator begin() { return ranges.begin(); }
287 iterator end() { return ranges.end(); }
289 typedef Ranges::const_iterator const_iterator;
290 const_iterator begin() const { return ranges.begin(); }
291 const_iterator end() const { return ranges.end(); }
293 typedef VNInfoList::iterator vni_iterator;
294 vni_iterator vni_begin() { return valnos.begin(); }
295 vni_iterator vni_end() { return valnos.end(); }
297 typedef VNInfoList::const_iterator const_vni_iterator;
298 const_vni_iterator vni_begin() const { return valnos.begin(); }
299 const_vni_iterator vni_end() const { return valnos.end(); }
301 /// advanceTo - Advance the specified iterator to point to the LiveRange
302 /// containing the specified position, or end() if the position is past the
303 /// end of the interval. If no LiveRange contains this position, but the
304 /// position is in a hole, this method returns an iterator pointing the the
305 /// LiveRange immediately after the hole.
306 iterator advanceTo(iterator I, unsigned Pos) {
307 if (Pos >= endNumber())
309 while (I->end <= Pos) ++I;
314 while (!valnos.empty()) {
315 VNInfo *VNI = valnos.back();
323 /// isStackSlot - Return true if this is a stack slot interval.
325 bool isStackSlot() const {
326 return reg & (1U << (sizeof(unsigned)*CHAR_BIT-1));
329 /// getStackSlotIndex - Return stack slot index if this is a stack slot
331 int getStackSlotIndex() const {
332 assert(isStackSlot() && "Interval is not a stack slot interval!");
333 return reg & ~(1U << (sizeof(unsigned)*CHAR_BIT-1));
336 bool hasAtLeastOneValue() const { return !valnos.empty(); }
338 bool containsOneValue() const { return valnos.size() == 1; }
340 unsigned getNumValNums() const { return (unsigned)valnos.size(); }
342 /// getValNumInfo - Returns pointer to the specified val#.
344 inline VNInfo *getValNumInfo(unsigned ValNo) {
345 return valnos[ValNo];
347 inline const VNInfo *getValNumInfo(unsigned ValNo) const {
348 return valnos[ValNo];
351 /// getNextValue - Create a new value number and return it. MIIdx specifies
352 /// the instruction that defines the value number.
353 VNInfo *getNextValue(unsigned MIIdx, MachineInstr *CopyMI,
354 bool isDefAccurate, BumpPtrAllocator &VNInfoAllocator) {
356 assert(MIIdx != ~0u && MIIdx != ~1u &&
357 "PHI def / unused flags should now be passed explicitly.");
359 static_cast<VNInfo*>(VNInfoAllocator.Allocate((unsigned)sizeof(VNInfo),
361 new (VNI) VNInfo((unsigned)valnos.size(), MIIdx, CopyMI);
362 VNI->setIsDefAccurate(isDefAccurate);
363 valnos.push_back(VNI);
367 /// Create a copy of the given value. The new value will be identical except
368 /// for the Value number.
369 VNInfo *createValueCopy(const VNInfo *orig, BumpPtrAllocator &VNInfoAllocator) {
372 static_cast<VNInfo*>(VNInfoAllocator.Allocate((unsigned)sizeof(VNInfo),
375 new (VNI) VNInfo((unsigned)valnos.size(), *orig);
376 valnos.push_back(VNI);
380 /// addKill - Add a kill instruction index to the specified value
382 static void addKill(VNInfo *VNI, unsigned KillIdx, bool phiKill) {
383 VNInfo::KillSet &kills = VNI->kills;
384 VNInfo::KillInfo newKill(phiKill, KillIdx);
386 kills.push_back(newKill);
388 VNInfo::KillSet::iterator
389 I = std::lower_bound(kills.begin(), kills.end(), newKill);
390 kills.insert(I, newKill);
394 /// addKills - Add a number of kills into the VNInfo kill vector. If this
395 /// interval is live at a kill point, then the kill is not added.
396 void addKills(VNInfo *VNI, const VNInfo::KillSet &kills) {
397 for (unsigned i = 0, e = static_cast<unsigned>(kills.size());
399 const VNInfo::KillInfo &Kill = kills[i];
400 if (!liveBeforeAndAt(Kill.killIdx)) {
401 VNInfo::KillSet::iterator
402 I = std::lower_bound(VNI->kills.begin(), VNI->kills.end(), Kill);
403 VNI->kills.insert(I, Kill);
408 /// removeKill - Remove the specified kill from the list of kills of
409 /// the specified val#.
410 static bool removeKill(VNInfo *VNI, unsigned KillIdx) {
411 VNInfo::KillSet &kills = VNI->kills;
412 VNInfo::KillSet::iterator
413 I = std::lower_bound(kills.begin(), kills.end(), KillIdx);
414 if (I != kills.end() && I->killIdx == KillIdx) {
421 /// removeKills - Remove all the kills in specified range
422 /// [Start, End] of the specified val#.
423 static void removeKills(VNInfo *VNI, unsigned Start, unsigned End) {
424 VNInfo::KillSet &kills = VNI->kills;
426 VNInfo::KillSet::iterator
427 I = std::lower_bound(kills.begin(), kills.end(), Start);
428 VNInfo::KillSet::iterator
429 E = std::upper_bound(kills.begin(), kills.end(), End);
433 /// isKill - Return true if the specified index is a kill of the
435 static bool isKill(const VNInfo *VNI, unsigned KillIdx) {
436 const VNInfo::KillSet &kills = VNI->kills;
437 VNInfo::KillSet::const_iterator
438 I = std::lower_bound(kills.begin(), kills.end(), KillIdx);
439 return I != kills.end() && I->killIdx == KillIdx;
442 /// isOnlyLROfValNo - Return true if the specified live range is the only
443 /// one defined by the its val#.
444 bool isOnlyLROfValNo(const LiveRange *LR) {
445 for (const_iterator I = begin(), E = end(); I != E; ++I) {
446 const LiveRange *Tmp = I;
447 if (Tmp != LR && Tmp->valno == LR->valno)
453 /// MergeValueNumberInto - This method is called when two value nubmers
454 /// are found to be equivalent. This eliminates V1, replacing all
455 /// LiveRanges with the V1 value number with the V2 value number. This can
456 /// cause merging of V1/V2 values numbers and compaction of the value space.
457 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2);
459 /// MergeInClobberRanges - For any live ranges that are not defined in the
460 /// current interval, but are defined in the Clobbers interval, mark them
461 /// used with an unknown definition value. Caller must pass in reference to
462 /// VNInfoAllocator since it will create a new val#.
463 void MergeInClobberRanges(const LiveInterval &Clobbers,
464 BumpPtrAllocator &VNInfoAllocator);
466 /// MergeInClobberRange - Same as MergeInClobberRanges except it merge in a
467 /// single LiveRange only.
468 void MergeInClobberRange(unsigned Start, unsigned End,
469 BumpPtrAllocator &VNInfoAllocator);
471 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
472 /// in RHS into this live interval as the specified value number.
473 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
474 /// current interval, it will replace the value numbers of the overlaped
475 /// live ranges with the specified value number.
476 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo);
478 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
479 /// in RHS into this live interval as the specified value number.
480 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
481 /// current interval, but only if the overlapping LiveRanges have the
482 /// specified value number.
483 void MergeValueInAsValue(const LiveInterval &RHS,
484 const VNInfo *RHSValNo, VNInfo *LHSValNo);
486 /// Copy - Copy the specified live interval. This copies all the fields
487 /// except for the register of the interval.
488 void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI,
489 BumpPtrAllocator &VNInfoAllocator);
491 bool empty() const { return ranges.empty(); }
493 /// beginNumber - Return the lowest numbered slot covered by interval.
494 unsigned beginNumber() const {
497 return ranges.front().start;
500 /// endNumber - return the maximum point of the interval of the whole,
502 unsigned endNumber() const {
505 return ranges.back().end;
508 bool expiredAt(unsigned index) const {
509 return index >= endNumber();
512 bool liveAt(unsigned index) const;
514 // liveBeforeAndAt - Check if the interval is live at the index and the
515 // index just before it. If index is liveAt, check if it starts a new live
516 // range.If it does, then check if the previous live range ends at index-1.
517 bool liveBeforeAndAt(unsigned index) const;
519 /// getLiveRangeContaining - Return the live range that contains the
520 /// specified index, or null if there is none.
521 const LiveRange *getLiveRangeContaining(unsigned Idx) const {
522 const_iterator I = FindLiveRangeContaining(Idx);
523 return I == end() ? 0 : &*I;
526 /// getLiveRangeContaining - Return the live range that contains the
527 /// specified index, or null if there is none.
528 LiveRange *getLiveRangeContaining(unsigned Idx) {
529 iterator I = FindLiveRangeContaining(Idx);
530 return I == end() ? 0 : &*I;
533 /// FindLiveRangeContaining - Return an iterator to the live range that
534 /// contains the specified index, or end() if there is none.
535 const_iterator FindLiveRangeContaining(unsigned Idx) const;
537 /// FindLiveRangeContaining - Return an iterator to the live range that
538 /// contains the specified index, or end() if there is none.
539 iterator FindLiveRangeContaining(unsigned Idx);
541 /// findDefinedVNInfo - Find the VNInfo that's defined at the specified
542 /// index (register interval) or defined by the specified register (stack
544 VNInfo *findDefinedVNInfo(unsigned DefIdxOrReg) const;
546 /// overlaps - Return true if the intersection of the two live intervals is
548 bool overlaps(const LiveInterval& other) const {
549 return overlapsFrom(other, other.begin());
552 /// overlaps - Return true if the live interval overlaps a range specified
554 bool overlaps(unsigned Start, unsigned End) const;
556 /// overlapsFrom - Return true if the intersection of the two live intervals
557 /// is not empty. The specified iterator is a hint that we can begin
558 /// scanning the Other interval starting at I.
559 bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
561 /// addRange - Add the specified LiveRange to this interval, merging
562 /// intervals as appropriate. This returns an iterator to the inserted live
563 /// range (which may have grown since it was inserted.
564 void addRange(LiveRange LR) {
565 addRangeFrom(LR, ranges.begin());
568 /// join - Join two live intervals (this, and other) together. This applies
569 /// mappings to the value numbers in the LHS/RHS intervals as specified. If
570 /// the intervals are not joinable, this aborts.
571 void join(LiveInterval &Other, const int *ValNoAssignments,
572 const int *RHSValNoAssignments,
573 SmallVector<VNInfo*, 16> &NewVNInfo,
574 MachineRegisterInfo *MRI);
576 /// isInOneLiveRange - Return true if the range specified is entirely in the
577 /// a single LiveRange of the live interval.
578 bool isInOneLiveRange(unsigned Start, unsigned End);
580 /// removeRange - Remove the specified range from this interval. Note that
581 /// the range must be a single LiveRange in its entirety.
582 void removeRange(unsigned Start, unsigned End, bool RemoveDeadValNo = false);
584 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) {
585 removeRange(LR.start, LR.end, RemoveDeadValNo);
588 /// removeValNo - Remove all the ranges defined by the specified value#.
589 /// Also remove the value# from value# list.
590 void removeValNo(VNInfo *ValNo);
592 /// scaleNumbering - Renumber VNI and ranges to provide gaps for new
594 void scaleNumbering(unsigned factor);
596 /// getSize - Returns the sum of sizes of all the LiveRange's.
598 unsigned getSize() const;
600 /// ComputeJoinedWeight - Set the weight of a live interval after
601 /// Other has been merged into it.
602 void ComputeJoinedWeight(const LiveInterval &Other);
604 bool operator<(const LiveInterval& other) const {
605 return beginNumber() < other.beginNumber();
608 void print(std::ostream &OS, const TargetRegisterInfo *TRI = 0) const;
609 void print(std::ostream *OS, const TargetRegisterInfo *TRI = 0) const {
610 if (OS) print(*OS, TRI);
612 void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const;
613 void print(raw_ostream *OS, const TargetRegisterInfo *TRI = 0) const {
614 if (OS) print(*OS, TRI);
620 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
621 void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd);
622 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr);
623 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
627 inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) {
631 inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) {