1 //===-- llvm/CodeGen/LiveInterval.h - Interval representation ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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/Streams.h"
34 /// LiveRange structure - This represents a simple register range in the
35 /// program, with an inclusive start point and an exclusive end point.
36 /// These ranges are rendered as [start,end).
38 unsigned start; // Start point of the interval (inclusive)
39 unsigned end; // End point of the interval (exclusive)
40 unsigned ValId; // identifier for the value contained in this interval.
42 LiveRange(unsigned S, unsigned E, unsigned V) : start(S), end(E), ValId(V) {
43 assert(S < E && "Cannot create empty or backwards range");
46 /// contains - Return true if the index is covered by this range.
48 bool contains(unsigned I) const {
49 return start <= I && I < end;
52 bool operator<(const LiveRange &LR) const {
53 return start < LR.start || (start == LR.start && end < LR.end);
55 bool operator==(const LiveRange &LR) const {
56 return start == LR.start && end == LR.end;
60 void print(std::ostream &os) const;
61 void print(std::ostream *os) const { if (os) print(*os); }
64 LiveRange(); // DO NOT IMPLEMENT
67 std::ostream& operator<<(std::ostream& os, const LiveRange &LR);
70 inline bool operator<(unsigned V, const LiveRange &LR) {
74 inline bool operator<(const LiveRange &LR, unsigned V) {
78 /// LiveInterval - This class represents some number of live ranges for a
79 /// register or value. This class also contains a bit of register allocator
82 typedef SmallVector<LiveRange,4> Ranges;
83 unsigned reg; // the register of this interval
84 unsigned preference; // preferred register to allocate for this interval
85 float weight; // weight of this interval
86 MachineInstr* remat; // definition if the definition rematerializable
87 Ranges ranges; // the ranges in which this register is live
89 /// ValueNumberInfo - If this value number is not defined by a copy, this
90 /// holds ~0,x. If the value number is not in use, it contains ~1,x to
91 /// indicate that the value # is not used. If the val# is defined by a
92 /// copy, the first entry is the instruction # of the copy, and the second
93 /// is the register number copied from.
94 SmallVector<std::pair<unsigned,unsigned>, 4> ValueNumberInfo;
97 LiveInterval(unsigned Reg, float Weight)
98 : reg(Reg), preference(0), weight(Weight), remat(NULL) {
101 typedef Ranges::iterator iterator;
102 iterator begin() { return ranges.begin(); }
103 iterator end() { return ranges.end(); }
105 typedef Ranges::const_iterator const_iterator;
106 const_iterator begin() const { return ranges.begin(); }
107 const_iterator end() const { return ranges.end(); }
110 /// advanceTo - Advance the specified iterator to point to the LiveRange
111 /// containing the specified position, or end() if the position is past the
112 /// end of the interval. If no LiveRange contains this position, but the
113 /// position is in a hole, this method returns an iterator pointing the the
114 /// LiveRange immediately after the hole.
115 iterator advanceTo(iterator I, unsigned Pos) {
116 if (Pos >= endNumber())
118 while (I->end <= Pos) ++I;
122 void swap(LiveInterval& other) {
123 std::swap(reg, other.reg);
124 std::swap(weight, other.weight);
125 std::swap(remat, other.remat);
126 std::swap(ranges, other.ranges);
127 std::swap(ValueNumberInfo, other.ValueNumberInfo);
130 bool containsOneValue() const { return ValueNumberInfo.size() == 1; }
132 unsigned getNumValNums() const { return ValueNumberInfo.size(); }
134 /// getNextValue - Create a new value number and return it. MIIdx specifies
135 /// the instruction that defines the value number.
136 unsigned getNextValue(unsigned MIIdx, unsigned SrcReg) {
137 ValueNumberInfo.push_back(std::make_pair(MIIdx, SrcReg));
138 return ValueNumberInfo.size()-1;
141 /// getInstForValNum - Return the machine instruction index that defines the
142 /// specified value number.
143 unsigned getInstForValNum(unsigned ValNo) const {
144 //assert(ValNo < ValueNumberInfo.size());
145 return ValueNumberInfo[ValNo].first;
148 unsigned getSrcRegForValNum(unsigned ValNo) const {
149 //assert(ValNo < ValueNumberInfo.size());
150 if (ValueNumberInfo[ValNo].first < ~2U)
151 return ValueNumberInfo[ValNo].second;
155 std::pair<unsigned, unsigned> getValNumInfo(unsigned ValNo) const {
156 //assert(ValNo < ValueNumberInfo.size());
157 return ValueNumberInfo[ValNo];
160 /// setValueNumberInfo - Change the value number info for the specified
162 void setValueNumberInfo(unsigned ValNo,
163 const std::pair<unsigned, unsigned> &I){
164 ValueNumberInfo[ValNo] = I;
167 /// MergeValueNumberInto - This method is called when two value nubmers
168 /// are found to be equivalent. This eliminates V1, replacing all
169 /// LiveRanges with the V1 value number with the V2 value number. This can
170 /// cause merging of V1/V2 values numbers and compaction of the value space.
171 void MergeValueNumberInto(unsigned V1, unsigned V2);
173 /// MergeInClobberRanges - For any live ranges that are not defined in the
174 /// current interval, but are defined in the Clobbers interval, mark them
175 /// used with an unknown definition value.
176 void MergeInClobberRanges(const LiveInterval &Clobbers);
179 /// MergeRangesInAsValue - Merge all of the intervals in RHS into this live
180 /// interval as the specified value number. The LiveRanges in RHS are
181 /// allowed to overlap with LiveRanges in the current interval, but only if
182 /// the overlapping LiveRanges have the specified value number.
183 void MergeRangesInAsValue(const LiveInterval &RHS, unsigned LHSValNo);
185 bool empty() const { return ranges.empty(); }
187 /// beginNumber - Return the lowest numbered slot covered by interval.
188 unsigned beginNumber() const {
189 assert(!empty() && "empty interval for register");
190 return ranges.front().start;
193 /// endNumber - return the maximum point of the interval of the whole,
195 unsigned endNumber() const {
196 assert(!empty() && "empty interval for register");
197 return ranges.back().end;
200 bool expiredAt(unsigned index) const {
201 return index >= endNumber();
204 bool liveAt(unsigned index) const;
206 /// getLiveRangeContaining - Return the live range that contains the
207 /// specified index, or null if there is none.
208 const LiveRange *getLiveRangeContaining(unsigned Idx) const {
209 const_iterator I = FindLiveRangeContaining(Idx);
210 return I == end() ? 0 : &*I;
213 /// FindLiveRangeContaining - Return an iterator to the live range that
214 /// contains the specified index, or end() if there is none.
215 const_iterator FindLiveRangeContaining(unsigned Idx) const;
217 /// FindLiveRangeContaining - Return an iterator to the live range that
218 /// contains the specified index, or end() if there is none.
219 iterator FindLiveRangeContaining(unsigned Idx);
221 /// getOverlapingRanges - Given another live interval which is defined as a
222 /// copy from this one, return a list of all of the live ranges where the
223 /// two overlap and have different value numbers.
224 void getOverlapingRanges(const LiveInterval &Other, unsigned CopyIdx,
225 std::vector<LiveRange*> &Ranges);
227 /// overlaps - Return true if the intersection of the two live intervals is
229 bool overlaps(const LiveInterval& other) const {
230 return overlapsFrom(other, other.begin());
233 /// overlapsFrom - Return true if the intersection of the two live intervals
234 /// is not empty. The specified iterator is a hint that we can begin
235 /// scanning the Other interval starting at I.
236 bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
238 /// addRange - Add the specified LiveRange to this interval, merging
239 /// intervals as appropriate. This returns an iterator to the inserted live
240 /// range (which may have grown since it was inserted.
241 void addRange(LiveRange LR) {
242 addRangeFrom(LR, ranges.begin());
245 /// join - Join two live intervals (this, and other) together. This applies
246 /// mappings to the value numbers in the LHS/RHS intervals as specified. If
247 /// the intervals are not joinable, this aborts.
248 void join(LiveInterval &Other, int *ValNoAssignments,
249 int *RHSValNoAssignments,
250 SmallVector<std::pair<unsigned,unsigned>,16> &NewValueNumberInfo);
252 /// removeRange - Remove the specified range from this interval. Note that
253 /// the range must already be in this interval in its entirety.
254 void removeRange(unsigned Start, unsigned End);
256 void removeRange(LiveRange LR) {
257 removeRange(LR.start, LR.end);
260 /// getSize - Returns the sum of sizes of all the LiveRange's.
262 unsigned getSize() const;
264 bool operator<(const LiveInterval& other) const {
265 return beginNumber() < other.beginNumber();
268 void print(std::ostream &OS, const MRegisterInfo *MRI = 0) const;
269 void print(std::ostream *OS, const MRegisterInfo *MRI = 0) const {
270 if (OS) print(*OS, MRI);
275 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
276 void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd);
277 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr);
278 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
281 inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) {