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"
31 class TargetRegisterInfo;
34 /// VNInfo - If the value number definition is undefined (e.g. phi
35 /// merge point), it contains ~0u,x. If the value number is not in use, it
36 /// contains ~1u,x to indicate that the value # is not used.
37 /// def - Instruction # of the definition.
38 /// - or reg # of the definition if it's a stack slot liveinterval.
39 /// copy - Copy iff val# is defined by a copy; zero otherwise.
40 /// hasPHIKill - One or more of the kills are PHI nodes.
41 /// redefByEC - Re-defined by early clobber somewhere during the live range.
42 /// kills - Instruction # of the kills.
49 SmallVector<unsigned, 4> kills;
51 : id(~1U), def(~1U), copy(0), hasPHIKill(false), redefByEC(false) {}
52 VNInfo(unsigned i, unsigned d, MachineInstr *c)
53 : id(i), def(d), copy(c), hasPHIKill(false), redefByEC(false) {}
56 /// LiveRange structure - This represents a simple register range in the
57 /// program, with an inclusive start point and an exclusive end point.
58 /// These ranges are rendered as [start,end).
60 unsigned start; // Start point of the interval (inclusive)
61 unsigned end; // End point of the interval (exclusive)
62 VNInfo *valno; // identifier for the value contained in this interval.
64 LiveRange(unsigned S, unsigned E, VNInfo *V) : start(S), end(E), valno(V) {
65 assert(S < E && "Cannot create empty or backwards range");
68 /// contains - Return true if the index is covered by this range.
70 bool contains(unsigned I) const {
71 return start <= I && I < end;
74 bool operator<(const LiveRange &LR) const {
75 return start < LR.start || (start == LR.start && end < LR.end);
77 bool operator==(const LiveRange &LR) const {
78 return start == LR.start && end == LR.end;
82 void print(std::ostream &os) const;
83 void print(std::ostream *os) const { if (os) print(*os); }
86 LiveRange(); // DO NOT IMPLEMENT
89 std::ostream& operator<<(std::ostream& os, const LiveRange &LR);
92 inline bool operator<(unsigned V, const LiveRange &LR) {
96 inline bool operator<(const LiveRange &LR, unsigned V) {
100 /// LiveInterval - This class represents some number of live ranges for a
101 /// register or value. This class also contains a bit of register allocator
103 struct LiveInterval {
104 typedef SmallVector<LiveRange,4> Ranges;
105 typedef SmallVector<VNInfo*,4> VNInfoList;
107 unsigned reg; // the register or stack slot of this interval
108 // if the top bits is set, it represents a stack slot.
109 float weight; // weight of this interval
110 unsigned short preference; // preferred register for this interval
111 Ranges ranges; // the ranges in which this register is live
112 VNInfoList valnos; // value#'s
115 LiveInterval(unsigned Reg, float Weight, bool IsSS = false)
116 : reg(Reg), weight(Weight), preference(0) {
118 reg = reg | (1U << (sizeof(unsigned)*8-1));
121 typedef Ranges::iterator iterator;
122 iterator begin() { return ranges.begin(); }
123 iterator end() { return ranges.end(); }
125 typedef Ranges::const_iterator const_iterator;
126 const_iterator begin() const { return ranges.begin(); }
127 const_iterator end() const { return ranges.end(); }
129 typedef VNInfoList::iterator vni_iterator;
130 vni_iterator vni_begin() { return valnos.begin(); }
131 vni_iterator vni_end() { return valnos.end(); }
133 typedef VNInfoList::const_iterator const_vni_iterator;
134 const_vni_iterator vni_begin() const { return valnos.begin(); }
135 const_vni_iterator vni_end() const { return valnos.end(); }
137 /// advanceTo - Advance the specified iterator to point to the LiveRange
138 /// containing the specified position, or end() if the position is past the
139 /// end of the interval. If no LiveRange contains this position, but the
140 /// position is in a hole, this method returns an iterator pointing the the
141 /// LiveRange immediately after the hole.
142 iterator advanceTo(iterator I, unsigned Pos) {
143 if (Pos >= endNumber())
145 while (I->end <= Pos) ++I;
150 while (!valnos.empty()) {
151 VNInfo *VNI = valnos.back();
159 /// isStackSlot - Return true if this is a stack slot interval.
161 bool isStackSlot() const {
162 return reg & (1U << (sizeof(unsigned)*8-1));
165 /// getStackSlotIndex - Return stack slot index if this is a stack slot
167 int getStackSlotIndex() const {
168 assert(isStackSlot() && "Interval is not a stack slot interval!");
169 return reg & ~(1U << (sizeof(unsigned)*8-1));
172 bool hasAtLeastOneValue() const { return !valnos.empty(); }
174 bool containsOneValue() const { return valnos.size() == 1; }
176 unsigned getNumValNums() const { return (unsigned)valnos.size(); }
178 /// getValNumInfo - Returns pointer to the specified val#.
180 inline VNInfo *getValNumInfo(unsigned ValNo) {
181 return valnos[ValNo];
183 inline const VNInfo *getValNumInfo(unsigned ValNo) const {
184 return valnos[ValNo];
187 /// copyValNumInfo - Copy the value number info for one value number to
189 void copyValNumInfo(VNInfo *DstValNo, const VNInfo *SrcValNo) {
190 DstValNo->def = SrcValNo->def;
191 DstValNo->copy = SrcValNo->copy;
192 DstValNo->hasPHIKill = SrcValNo->hasPHIKill;
193 DstValNo->redefByEC = SrcValNo->redefByEC;
194 DstValNo->kills = SrcValNo->kills;
197 /// getNextValue - Create a new value number and return it. MIIdx specifies
198 /// the instruction that defines the value number.
199 VNInfo *getNextValue(unsigned MIIdx, MachineInstr *CopyMI,
200 BumpPtrAllocator &VNInfoAllocator) {
202 unsigned Alignment = (unsigned)__alignof__(VNInfo);
205 unsigned Alignment = 8;
208 static_cast<VNInfo*>(VNInfoAllocator.Allocate((unsigned)sizeof(VNInfo),
210 new (VNI) VNInfo((unsigned)valnos.size(), MIIdx, CopyMI);
211 valnos.push_back(VNI);
215 /// getUnknownValNo - Find a value# for unknown values, if there isn't one
216 /// create a new one.
217 VNInfo *getUnknownValNo(BumpPtrAllocator &VNInfoAllocator);
219 /// addKill - Add a kill instruction index to the specified value
221 static void addKill(VNInfo *VNI, unsigned KillIdx) {
222 SmallVector<unsigned, 4> &kills = VNI->kills;
224 kills.push_back(KillIdx);
226 SmallVector<unsigned, 4>::iterator
227 I = std::lower_bound(kills.begin(), kills.end(), KillIdx);
228 kills.insert(I, KillIdx);
232 /// addKills - Add a number of kills into the VNInfo kill vector. If this
233 /// interval is live at a kill point, then the kill is not added.
234 void addKills(VNInfo *VNI, const SmallVector<unsigned, 4> &kills) {
235 for (unsigned i = 0, e = static_cast<unsigned>(kills.size());
237 unsigned KillIdx = kills[i];
238 if (!liveBeforeAndAt(KillIdx)) {
239 SmallVector<unsigned, 4>::iterator
240 I = std::lower_bound(VNI->kills.begin(), VNI->kills.end(), KillIdx);
241 VNI->kills.insert(I, KillIdx);
246 /// removeKill - Remove the specified kill from the list of kills of
247 /// the specified val#.
248 static bool removeKill(VNInfo *VNI, unsigned KillIdx) {
249 SmallVector<unsigned, 4> &kills = VNI->kills;
250 SmallVector<unsigned, 4>::iterator
251 I = std::lower_bound(kills.begin(), kills.end(), KillIdx);
252 if (I != kills.end() && *I == KillIdx) {
259 /// removeKills - Remove all the kills in specified range
260 /// [Start, End] of the specified val#.
261 static void removeKills(VNInfo *VNI, unsigned Start, unsigned End) {
262 SmallVector<unsigned, 4> &kills = VNI->kills;
263 SmallVector<unsigned, 4>::iterator
264 I = std::lower_bound(kills.begin(), kills.end(), Start);
265 SmallVector<unsigned, 4>::iterator
266 E = std::upper_bound(kills.begin(), kills.end(), End);
270 /// isKill - Return true if the specified index is a kill of the
272 static bool isKill(const VNInfo *VNI, unsigned KillIdx) {
273 const SmallVector<unsigned, 4> &kills = VNI->kills;
274 SmallVector<unsigned, 4>::const_iterator
275 I = std::lower_bound(kills.begin(), kills.end(), KillIdx);
276 return I != kills.end() && *I == KillIdx;
279 /// isOnlyLROfValNo - Return true if the specified live range is the only
280 /// one defined by the its val#.
281 bool isOnlyLROfValNo( const LiveRange *LR) {
282 for (const_iterator I = begin(), E = end(); I != E; ++I) {
283 const LiveRange *Tmp = I;
284 if (Tmp != LR && Tmp->valno == LR->valno)
290 /// MergeValueNumberInto - This method is called when two value nubmers
291 /// are found to be equivalent. This eliminates V1, replacing all
292 /// LiveRanges with the V1 value number with the V2 value number. This can
293 /// cause merging of V1/V2 values numbers and compaction of the value space.
294 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2);
296 /// MergeInClobberRanges - For any live ranges that are not defined in the
297 /// current interval, but are defined in the Clobbers interval, mark them
298 /// used with an unknown definition value. Caller must pass in reference to
299 /// VNInfoAllocator since it will create a new val#.
300 void MergeInClobberRanges(const LiveInterval &Clobbers,
301 BumpPtrAllocator &VNInfoAllocator);
303 /// MergeInClobberRange - Same as MergeInClobberRanges except it merge in a
304 /// single LiveRange only.
305 void MergeInClobberRange(unsigned Start, unsigned End,
306 BumpPtrAllocator &VNInfoAllocator);
308 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
309 /// in RHS into this live interval as the specified value number.
310 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
311 /// current interval, it will replace the value numbers of the overlaped
312 /// live ranges with the specified value number.
313 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo);
315 /// MergeValueInAsValue - Merge all of the live ranges of a specific val#
316 /// in RHS into this live interval as the specified value number.
317 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
318 /// current interval, but only if the overlapping LiveRanges have the
319 /// specified value number.
320 void MergeValueInAsValue(const LiveInterval &RHS,
321 const VNInfo *RHSValNo, VNInfo *LHSValNo);
323 /// Copy - Copy the specified live interval. This copies all the fields
324 /// except for the register of the interval.
325 void Copy(const LiveInterval &RHS, BumpPtrAllocator &VNInfoAllocator);
327 bool empty() const { return ranges.empty(); }
329 /// beginNumber - Return the lowest numbered slot covered by interval.
330 unsigned beginNumber() const {
333 return ranges.front().start;
336 /// endNumber - return the maximum point of the interval of the whole,
338 unsigned endNumber() const {
341 return ranges.back().end;
344 bool expiredAt(unsigned index) const {
345 return index >= endNumber();
348 bool liveAt(unsigned index) const;
350 // liveBeforeAndAt - Check if the interval is live at the index and the
351 // index just before it. If index is liveAt, check if it starts a new live
352 // range.If it does, then check if the previous live range ends at index-1.
353 bool liveBeforeAndAt(unsigned index) const;
355 /// getLiveRangeContaining - Return the live range that contains the
356 /// specified index, or null if there is none.
357 const LiveRange *getLiveRangeContaining(unsigned Idx) const {
358 const_iterator I = FindLiveRangeContaining(Idx);
359 return I == end() ? 0 : &*I;
362 /// FindLiveRangeContaining - Return an iterator to the live range that
363 /// contains the specified index, or end() if there is none.
364 const_iterator FindLiveRangeContaining(unsigned Idx) const;
366 /// FindLiveRangeContaining - Return an iterator to the live range that
367 /// contains the specified index, or end() if there is none.
368 iterator FindLiveRangeContaining(unsigned Idx);
370 /// findDefinedVNInfo - Find the VNInfo that's defined at the specified
371 /// index (register interval) or defined by the specified register (stack
373 VNInfo *findDefinedVNInfo(unsigned DefIdxOrReg) const;
375 /// overlaps - Return true if the intersection of the two live intervals is
377 bool overlaps(const LiveInterval& other) const {
378 return overlapsFrom(other, other.begin());
381 /// overlapsFrom - Return true if the intersection of the two live intervals
382 /// is not empty. The specified iterator is a hint that we can begin
383 /// scanning the Other interval starting at I.
384 bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
386 /// addRange - Add the specified LiveRange to this interval, merging
387 /// intervals as appropriate. This returns an iterator to the inserted live
388 /// range (which may have grown since it was inserted.
389 void addRange(LiveRange LR) {
390 addRangeFrom(LR, ranges.begin());
393 /// join - Join two live intervals (this, and other) together. This applies
394 /// mappings to the value numbers in the LHS/RHS intervals as specified. If
395 /// the intervals are not joinable, this aborts.
396 void join(LiveInterval &Other, const int *ValNoAssignments,
397 const int *RHSValNoAssignments,
398 SmallVector<VNInfo*, 16> &NewVNInfo);
400 /// isInOneLiveRange - Return true if the range specified is entirely in the
401 /// a single LiveRange of the live interval.
402 bool isInOneLiveRange(unsigned Start, unsigned End);
404 /// removeRange - Remove the specified range from this interval. Note that
405 /// the range must be a single LiveRange in its entirety.
406 void removeRange(unsigned Start, unsigned End, bool RemoveDeadValNo = false);
408 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) {
409 removeRange(LR.start, LR.end, RemoveDeadValNo);
412 /// removeValNo - Remove all the ranges defined by the specified value#.
413 /// Also remove the value# from value# list.
414 void removeValNo(VNInfo *ValNo);
416 /// getSize - Returns the sum of sizes of all the LiveRange's.
418 unsigned getSize() const;
420 bool operator<(const LiveInterval& other) const {
421 return beginNumber() < other.beginNumber();
424 void print(std::ostream &OS, const TargetRegisterInfo *TRI = 0) const;
425 void print(std::ostream *OS, const TargetRegisterInfo *TRI = 0) const {
426 if (OS) print(*OS, TRI);
431 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
432 void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd);
433 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr);
434 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
437 inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) {