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
66 /// Holds information about individual kills.
69 unsigned killIdx : 31;
71 KillInfo(bool isPHIKill, unsigned killIdx)
72 : isPHIKill(isPHIKill), killIdx(killIdx) {
74 assert(killIdx != 0 && "Zero kill indices are no longer permitted.");
79 typedef SmallVector<KillInfo, 4> KillSet;
81 /// The ID number of this value.
84 /// The index of the defining instruction (if isDefAccurate() returns true).
90 : flags(IS_UNUSED), id(~1U), def(0), copy(0) {}
92 /// VNInfo constructor.
93 /// d is presumed to point to the actual defining instr. If it doesn't
94 /// setIsDefAccurate(false) should be called after construction.
95 VNInfo(unsigned i, unsigned d, MachineInstr *c)
96 : flags(IS_DEF_ACCURATE), id(i), def(d), copy(c) {}
98 /// VNInfo construtor, copies values from orig, except for the value number.
99 VNInfo(unsigned i, const VNInfo &orig)
100 : flags(orig.flags), id(i), def(orig.def), copy(orig.copy),
103 /// Used for copying value number info.
104 unsigned getFlags() const { return flags; }
105 void setFlags(unsigned flags) { this->flags = flags; }
107 /// Returns true if one or more kills are PHI nodes.
108 bool hasPHIKill() const { return flags & HAS_PHI_KILL; }
109 void setHasPHIKill(bool hasKill) {
111 flags |= HAS_PHI_KILL;
113 flags &= ~HAS_PHI_KILL;
116 /// Returns true if this value is re-defined by an early clobber somewhere
117 /// during the live range.
118 bool hasRedefByEC() const { return flags & REDEF_BY_EC; }
119 void setHasRedefByEC(bool hasRedef) {
121 flags |= REDEF_BY_EC;
123 flags &= ~REDEF_BY_EC;
126 /// Returns true if this value is defined by a PHI instruction (or was,
127 /// PHI instrucions may have been eliminated).
128 bool isPHIDef() const { return flags & IS_PHI_DEF; }
129 void setIsPHIDef(bool phiDef) {
133 flags &= ~IS_PHI_DEF;
136 /// Returns true if this value is unused.
137 bool isUnused() const { return flags & IS_UNUSED; }
138 void setIsUnused(bool unused) {
145 /// Returns true if the def is accurate.
146 bool isDefAccurate() const { return flags & IS_DEF_ACCURATE; }
147 void setIsDefAccurate(bool defAccurate) {
149 flags |= IS_DEF_ACCURATE;
151 flags &= ~IS_DEF_ACCURATE;
156 inline bool operator<(const VNInfo::KillInfo &k1, const VNInfo::KillInfo &k2) {
157 return k1.killIdx < k2.killIdx;
160 inline bool operator<(const VNInfo::KillInfo &k, unsigned idx) {
161 return k.killIdx < idx;
164 inline bool operator<(unsigned idx, const VNInfo::KillInfo &k) {
165 return idx < k.killIdx;
168 /// LiveRange structure - This represents a simple register range in the
169 /// program, with an inclusive start point and an exclusive end point.
170 /// These ranges are rendered as [start,end).
172 unsigned start; // Start point of the interval (inclusive)
173 unsigned end; // End point of the interval (exclusive)
174 VNInfo *valno; // identifier for the value contained in this interval.
176 LiveRange(unsigned S, unsigned E, VNInfo *V) : start(S), end(E), valno(V) {
177 assert(S < E && "Cannot create empty or backwards range");
180 /// contains - Return true if the index is covered by this range.
182 bool contains(unsigned I) const {
183 return start <= I && I < end;
186 bool operator<(const LiveRange &LR) const {
187 return start < LR.start || (start == LR.start && end < LR.end);
189 bool operator==(const LiveRange &LR) const {
190 return start == LR.start && end == LR.end;
194 void print(std::ostream &os) const;
195 void print(std::ostream *os) const { if (os) print(*os); }
196 void print(raw_ostream &os) const;
197 void print(raw_ostream *os) const { if (os) print(*os); }
200 LiveRange(); // DO NOT IMPLEMENT
203 std::ostream& operator<<(std::ostream& os, const LiveRange &LR);
204 raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR);
207 inline bool operator<(unsigned V, const LiveRange &LR) {
211 inline bool operator<(const LiveRange &LR, unsigned V) {
215 /// LiveInterval - This class represents some number of live ranges for a
216 /// register or value. This class also contains a bit of register allocator
221 typedef SmallVector<LiveRange,4> Ranges;
222 typedef SmallVector<VNInfo*,4> VNInfoList;
224 unsigned reg; // the register or stack slot of this interval
225 // if the top bits is set, it represents a stack slot.
226 float weight; // weight of this interval
227 Ranges ranges; // the ranges in which this register is live
228 VNInfoList valnos; // value#'s
239 static unsigned scale(unsigned slot, unsigned factor) {
240 unsigned index = slot / NUM,
242 assert(index <= ~0U / (factor * NUM) &&
243 "Rescaled interval would overflow");
244 return index * NUM * factor + offset;
249 LiveInterval(unsigned Reg, float Weight, bool IsSS = false)
250 : reg(Reg), weight(Weight) {
252 reg = reg | (1U << (sizeof(unsigned)*CHAR_BIT-1));
255 typedef Ranges::iterator iterator;
256 iterator begin() { return ranges.begin(); }
257 iterator end() { return ranges.end(); }
259 typedef Ranges::const_iterator const_iterator;
260 const_iterator begin() const { return ranges.begin(); }
261 const_iterator end() const { return ranges.end(); }
263 typedef VNInfoList::iterator vni_iterator;
264 vni_iterator vni_begin() { return valnos.begin(); }
265 vni_iterator vni_end() { return valnos.end(); }
267 typedef VNInfoList::const_iterator const_vni_iterator;
268 const_vni_iterator vni_begin() const { return valnos.begin(); }
269 const_vni_iterator vni_end() const { return valnos.end(); }
271 /// advanceTo - Advance the specified iterator to point to the LiveRange
272 /// containing the specified position, or end() if the position is past the
273 /// end of the interval. If no LiveRange contains this position, but the
274 /// position is in a hole, this method returns an iterator pointing the the
275 /// LiveRange immediately after the hole.
276 iterator advanceTo(iterator I, unsigned Pos) {
277 if (Pos >= endNumber())
279 while (I->end <= Pos) ++I;
284 while (!valnos.empty()) {
285 VNInfo *VNI = valnos.back();
293 /// isStackSlot - Return true if this is a stack slot interval.
295 bool isStackSlot() const {
296 return reg & (1U << (sizeof(unsigned)*CHAR_BIT-1));
299 /// getStackSlotIndex - Return stack slot index if this is a stack slot
301 int getStackSlotIndex() const {
302 assert(isStackSlot() && "Interval is not a stack slot interval!");
303 return reg & ~(1U << (sizeof(unsigned)*CHAR_BIT-1));
306 bool hasAtLeastOneValue() const { return !valnos.empty(); }
308 bool containsOneValue() const { return valnos.size() == 1; }
310 unsigned getNumValNums() const { return (unsigned)valnos.size(); }
312 /// getValNumInfo - Returns pointer to the specified val#.
314 inline VNInfo *getValNumInfo(unsigned ValNo) {
315 return valnos[ValNo];
317 inline const VNInfo *getValNumInfo(unsigned ValNo) const {
318 return valnos[ValNo];
321 /// copyValNumInfo - Copy the value number info for one value number to
323 void copyValNumInfo(VNInfo *DstValNo, const VNInfo *SrcValNo) {
324 DstValNo->def = SrcValNo->def;
325 DstValNo->copy = SrcValNo->copy;
326 DstValNo->setFlags(SrcValNo->getFlags());
327 DstValNo->kills = SrcValNo->kills;
330 /// getNextValue - Create a new value number and return it. MIIdx specifies
331 /// the instruction that defines the value number.
332 VNInfo *getNextValue(unsigned MIIdx, MachineInstr *CopyMI,
333 bool isDefAccurate, BumpPtrAllocator &VNInfoAllocator) {
335 assert(MIIdx != ~0u && MIIdx != ~1u &&
336 "PHI def / unused flags should now be passed explicitly.");
338 static_cast<VNInfo*>(VNInfoAllocator.Allocate((unsigned)sizeof(VNInfo),
340 new (VNI) VNInfo((unsigned)valnos.size(), MIIdx, CopyMI);
341 VNI->setIsDefAccurate(isDefAccurate);
342 valnos.push_back(VNI);
346 /// Create a copy of the given value. The new value will be identical except
347 /// for the Value number.
348 VNInfo *createValueCopy(const VNInfo *orig, BumpPtrAllocator &VNInfoAllocator) {
351 static_cast<VNInfo*>(VNInfoAllocator.Allocate((unsigned)sizeof(VNInfo),
354 new (VNI) VNInfo((unsigned)valnos.size(), *orig);
355 valnos.push_back(VNI);
359 /// addKill - Add a kill instruction index to the specified value
361 static void addKill(VNInfo *VNI, unsigned KillIdx, bool phiKill) {
362 VNInfo::KillSet &kills = VNI->kills;
363 VNInfo::KillInfo newKill(phiKill, KillIdx);
365 kills.push_back(newKill);
367 VNInfo::KillSet::iterator
368 I = std::lower_bound(kills.begin(), kills.end(), newKill);
369 kills.insert(I, newKill);
373 /// addKills - Add a number of kills into the VNInfo kill vector. If this
374 /// interval is live at a kill point, then the kill is not added.
375 void addKills(VNInfo *VNI, const VNInfo::KillSet &kills) {
376 for (unsigned i = 0, e = static_cast<unsigned>(kills.size());
378 const VNInfo::KillInfo &Kill = kills[i];
379 if (!liveBeforeAndAt(Kill.killIdx)) {
380 VNInfo::KillSet::iterator
381 I = std::lower_bound(VNI->kills.begin(), VNI->kills.end(), Kill);
382 VNI->kills.insert(I, Kill);
387 /// removeKill - Remove the specified kill from the list of kills of
388 /// the specified val#.
389 static bool removeKill(VNInfo *VNI, unsigned KillIdx) {
390 VNInfo::KillSet &kills = VNI->kills;
391 VNInfo::KillSet::iterator
392 I = std::lower_bound(kills.begin(), kills.end(), KillIdx);
393 if (I != kills.end() && I->killIdx == KillIdx) {
400 /// removeKills - Remove all the kills in specified range
401 /// [Start, End] of the specified val#.
402 static void removeKills(VNInfo *VNI, unsigned Start, unsigned End) {
403 VNInfo::KillSet &kills = VNI->kills;
405 VNInfo::KillSet::iterator
406 I = std::lower_bound(kills.begin(), kills.end(), Start);
407 VNInfo::KillSet::iterator
408 E = std::upper_bound(kills.begin(), kills.end(), End);
412 /// isKill - Return true if the specified index is a kill of the
414 static bool isKill(const VNInfo *VNI, unsigned KillIdx) {
415 const VNInfo::KillSet &kills = VNI->kills;
416 VNInfo::KillSet::const_iterator
417 I = std::lower_bound(kills.begin(), kills.end(), KillIdx);
418 return I != kills.end() && I->killIdx == KillIdx;
421 /// isOnlyLROfValNo - Return true if the specified live range is the only
422 /// one defined by the its val#.
423 bool isOnlyLROfValNo(const LiveRange *LR) {
424 for (const_iterator I = begin(), E = end(); I != E; ++I) {
425 const LiveRange *Tmp = I;
426 if (Tmp != LR && Tmp->valno == LR->valno)
432 /// MergeValueNumberInto - This method is called when two value nubmers
433 /// are found to be equivalent. This eliminates V1, replacing all
434 /// LiveRanges with the V1 value number with the V2 value number. This can
435 /// cause merging of V1/V2 values numbers and compaction of the value space.
436 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2);
438 /// MergeInClobberRanges - For any live ranges that are not defined in the
439 /// current interval, but are defined in the Clobbers interval, mark them
440 /// used with an unknown definition value. Caller must pass in reference to
441 /// VNInfoAllocator since it will create a new val#.
442 void MergeInClobberRanges(const LiveInterval &Clobbers,
443 BumpPtrAllocator &VNInfoAllocator);
445 /// MergeInClobberRange - Same as MergeInClobberRanges except it merge in a
446 /// single LiveRange only.
447 void MergeInClobberRange(unsigned Start, unsigned End,
448 BumpPtrAllocator &VNInfoAllocator);
450 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
451 /// in RHS into this live interval as the specified value number.
452 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
453 /// current interval, it will replace the value numbers of the overlaped
454 /// live ranges with the specified value number.
455 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo);
457 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
458 /// in RHS into this live interval as the specified value number.
459 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
460 /// current interval, but only if the overlapping LiveRanges have the
461 /// specified value number.
462 void MergeValueInAsValue(const LiveInterval &RHS,
463 const VNInfo *RHSValNo, VNInfo *LHSValNo);
465 /// Copy - Copy the specified live interval. This copies all the fields
466 /// except for the register of the interval.
467 void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI,
468 BumpPtrAllocator &VNInfoAllocator);
470 bool empty() const { return ranges.empty(); }
472 /// beginNumber - Return the lowest numbered slot covered by interval.
473 unsigned beginNumber() const {
476 return ranges.front().start;
479 /// endNumber - return the maximum point of the interval of the whole,
481 unsigned endNumber() const {
484 return ranges.back().end;
487 bool expiredAt(unsigned index) const {
488 return index >= endNumber();
491 bool liveAt(unsigned index) const;
493 // liveBeforeAndAt - Check if the interval is live at the index and the
494 // index just before it. If index is liveAt, check if it starts a new live
495 // range.If it does, then check if the previous live range ends at index-1.
496 bool liveBeforeAndAt(unsigned index) const;
498 /// getLiveRangeContaining - Return the live range that contains the
499 /// specified index, or null if there is none.
500 const LiveRange *getLiveRangeContaining(unsigned Idx) const {
501 const_iterator I = FindLiveRangeContaining(Idx);
502 return I == end() ? 0 : &*I;
505 /// getLiveRangeContaining - Return the live range that contains the
506 /// specified index, or null if there is none.
507 LiveRange *getLiveRangeContaining(unsigned Idx) {
508 iterator I = FindLiveRangeContaining(Idx);
509 return I == end() ? 0 : &*I;
512 /// FindLiveRangeContaining - Return an iterator to the live range that
513 /// contains the specified index, or end() if there is none.
514 const_iterator FindLiveRangeContaining(unsigned Idx) const;
516 /// FindLiveRangeContaining - Return an iterator to the live range that
517 /// contains the specified index, or end() if there is none.
518 iterator FindLiveRangeContaining(unsigned Idx);
520 /// findDefinedVNInfo - Find the VNInfo that's defined at the specified
521 /// index (register interval) or defined by the specified register (stack
523 VNInfo *findDefinedVNInfo(unsigned DefIdxOrReg) const;
525 /// overlaps - Return true if the intersection of the two live intervals is
527 bool overlaps(const LiveInterval& other) const {
528 return overlapsFrom(other, other.begin());
531 /// overlaps - Return true if the live interval overlaps a range specified
533 bool overlaps(unsigned Start, unsigned End) const;
535 /// overlapsFrom - Return true if the intersection of the two live intervals
536 /// is not empty. The specified iterator is a hint that we can begin
537 /// scanning the Other interval starting at I.
538 bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
540 /// addRange - Add the specified LiveRange to this interval, merging
541 /// intervals as appropriate. This returns an iterator to the inserted live
542 /// range (which may have grown since it was inserted.
543 void addRange(LiveRange LR) {
544 addRangeFrom(LR, ranges.begin());
547 /// join - Join two live intervals (this, and other) together. This applies
548 /// mappings to the value numbers in the LHS/RHS intervals as specified. If
549 /// the intervals are not joinable, this aborts.
550 void join(LiveInterval &Other, const int *ValNoAssignments,
551 const int *RHSValNoAssignments,
552 SmallVector<VNInfo*, 16> &NewVNInfo,
553 MachineRegisterInfo *MRI);
555 /// isInOneLiveRange - Return true if the range specified is entirely in the
556 /// a single LiveRange of the live interval.
557 bool isInOneLiveRange(unsigned Start, unsigned End);
559 /// removeRange - Remove the specified range from this interval. Note that
560 /// the range must be a single LiveRange in its entirety.
561 void removeRange(unsigned Start, unsigned End, bool RemoveDeadValNo = false);
563 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) {
564 removeRange(LR.start, LR.end, RemoveDeadValNo);
567 /// removeValNo - Remove all the ranges defined by the specified value#.
568 /// Also remove the value# from value# list.
569 void removeValNo(VNInfo *ValNo);
571 /// scaleNumbering - Renumber VNI and ranges to provide gaps for new
573 void scaleNumbering(unsigned factor);
575 /// getSize - Returns the sum of sizes of all the LiveRange's.
577 unsigned getSize() const;
579 /// ComputeJoinedWeight - Set the weight of a live interval after
580 /// Other has been merged into it.
581 void ComputeJoinedWeight(const LiveInterval &Other);
583 bool operator<(const LiveInterval& other) const {
584 return beginNumber() < other.beginNumber();
587 void print(std::ostream &OS, const TargetRegisterInfo *TRI = 0) const;
588 void print(std::ostream *OS, const TargetRegisterInfo *TRI = 0) const {
589 if (OS) print(*OS, TRI);
591 void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const;
592 void print(raw_ostream *OS, const TargetRegisterInfo *TRI = 0) const {
593 if (OS) print(*OS, TRI);
599 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
600 void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd);
601 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr);
602 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
606 inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) {
610 inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) {