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
31 /// LiveRange structure - This represents a simple register range in the
32 /// program, with an inclusive start point and an exclusive end point.
33 /// These ranges are rendered as [start,end).
35 unsigned start; // Start point of the interval (inclusive)
36 unsigned end; // End point of the interval (exclusive)
37 unsigned ValId; // identifier for the value contained in this interval.
39 LiveRange(unsigned S, unsigned E, unsigned V) : start(S), end(E), ValId(V) {
40 assert(S < E && "Cannot create empty or backwards range");
43 /// contains - Return true if the index is covered by this range.
45 bool contains(unsigned I) const {
46 return start <= I && I < end;
49 bool operator<(const LiveRange &LR) const {
50 return start < LR.start || (start == LR.start && end < LR.end);
52 bool operator==(const LiveRange &LR) const {
53 return start == LR.start && end == LR.end;
59 LiveRange(); // DO NOT IMPLEMENT
61 std::ostream& operator<<(std::ostream& os, const LiveRange &LR);
63 inline bool operator<(unsigned V, const LiveRange &LR) {
67 inline bool operator<(const LiveRange &LR, unsigned V) {
71 /// LiveInterval - This class represents some number of live ranges for a
72 /// register or value. This class also contains a bit of register allocator
75 typedef std::vector<LiveRange> Ranges;
76 unsigned reg; // the register of this interval
77 float weight; // weight of this interval
78 Ranges ranges; // the ranges in which this register is live
80 LiveInterval(unsigned Reg, float Weight)
81 : reg(Reg), weight(Weight), NumValues(0) {
84 typedef Ranges::iterator iterator;
85 iterator begin() { return ranges.begin(); }
86 iterator end() { return ranges.end(); }
88 typedef Ranges::const_iterator const_iterator;
89 const_iterator begin() const { return ranges.begin(); }
90 const_iterator end() const { return ranges.end(); }
93 /// advanceTo - Advance the specified iterator to point to the LiveRange
94 /// containing the specified position, or end() if the position is past the
95 /// end of the interval. If no LiveRange contains this position, but the
96 /// position is in a hole, this method returns an iterator pointing the the
97 /// LiveRange immediately after the hole.
98 iterator advanceTo(iterator I, unsigned Pos) {
99 if (Pos >= endNumber())
101 while (I->end <= Pos) ++I;
105 void swap(LiveInterval& other) {
106 std::swap(reg, other.reg);
107 std::swap(weight, other.weight);
108 ranges.swap(other.ranges);
109 std::swap(NumValues, other.NumValues);
112 bool containsOneValue() const { return NumValues == 1; }
114 unsigned getNextValue() {
118 bool empty() const { return ranges.empty(); }
120 /// beginNumber - Return the lowest numbered slot covered by interval.
121 unsigned beginNumber() const {
122 assert(!empty() && "empty interval for register");
123 return ranges.front().start;
126 /// endNumber - return the maximum point of the interval of the whole,
128 unsigned endNumber() const {
129 assert(!empty() && "empty interval for register");
130 return ranges.back().end;
133 bool expiredAt(unsigned index) const {
134 return index >= endNumber();
137 bool liveAt(unsigned index) const;
139 /// getLiveRangeContaining - Return the live range that contains the
140 /// specified index, or null if there is none.
141 const LiveRange *getLiveRangeContaining(unsigned Idx) const;
144 /// joinable - Two intervals are joinable if the either don't overlap at all
145 /// or if the destination of the copy is a single assignment value, and it
146 /// only overlaps with one value in the source interval.
147 bool joinable(const LiveInterval& other, unsigned CopyIdx) const;
149 /// getOverlapingRanges - Given another live interval which is defined as a
150 /// copy from this one, return a list of all of the live ranges where the
151 /// two overlap and have different value numbers.
152 void getOverlapingRanges(const LiveInterval &Other, unsigned CopyIdx,
153 std::vector<LiveRange*> &Ranges);
155 /// overlaps - Return true if the intersection of the two live intervals is
157 bool overlaps(const LiveInterval& other) const {
158 return overlapsFrom(other, other.begin());
161 /// overlapsFrom - Return true if the intersection of the two live intervals
162 /// is not empty. The specified iterator is a hint that we can begin
163 /// scanning the Other interval starting at I.
164 bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
166 /// addRange - Add the specified LiveRange to this interval, merging
167 /// intervals as appropriate. This returns an iterator to the inserted live
168 /// range (which may have grown since it was inserted.
169 void addRange(LiveRange LR) {
170 addRangeFrom(LR, ranges.begin());
173 /// join - Join two live intervals (this, and other) together. This
174 /// operation is the result of a copy instruction in the source program,
175 /// that occurs at index 'CopyIdx' that copies from 'other' to 'this'. This
176 /// destroys 'other'.
177 void join(LiveInterval& other, unsigned CopyIdx);
180 /// removeRange - Remove the specified range from this interval. Note that
181 /// the range must already be in this interval in its entirety.
182 void removeRange(unsigned Start, unsigned End);
184 bool operator<(const LiveInterval& other) const {
185 return beginNumber() < other.beginNumber();
188 void print(std::ostream &OS, const MRegisterInfo *MRI = 0) const;
192 unsigned NumValues; // the number of distinct values in this interval.
193 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
194 void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd);
195 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr);
196 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
199 inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) {