1 //===-- LiveIntervalAnalysis.h - Live Interval Analysis ---------*- 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 LiveInterval analysis pass. Given some numbering of
11 // each the machine instructions (in this implemention depth-first order) an
12 // interval [i, j) is said to be a live interval for register v if there is no
13 // instruction with number j' > j such that v is live at j' abd there is no
14 // instruction with number i' < i such that v is live at i'. In this
15 // implementation intervals can have holes, i.e. an interval might look like
16 // [1,20), [50,65), [1000,1001).
18 //===----------------------------------------------------------------------===//
20 #ifndef LLVM_CODEGEN_LIVEINTERVAL_ANALYSIS_H
21 #define LLVM_CODEGEN_LIVEINTERVAL_ANALYSIS_H
23 #include "llvm/ADT/DenseMap.h"
24 #include "llvm/CodeGen/MachineFunctionPass.h"
25 #include "llvm/CodeGen/LiveInterval.h"
31 class TargetInstrInfo;
34 class LiveIntervals : public MachineFunctionPass {
36 const TargetMachine* tm_;
37 const MRegisterInfo* mri_;
38 const TargetInstrInfo* tii_;
41 /// MBB2IdxMap - The index of the first instruction in the specified basic
43 std::vector<unsigned> MBB2IdxMap;
45 typedef std::map<MachineInstr*, unsigned> Mi2IndexMap;
48 typedef std::vector<MachineInstr*> Index2MiMap;
51 typedef std::map<unsigned, LiveInterval> Reg2IntervalMap;
52 Reg2IntervalMap r2iMap_;
54 typedef DenseMap<unsigned> Reg2RegMap;
57 std::vector<bool> allocatableRegs_;
62 unsigned SrcReg, DstReg;
64 CopyRec getCopyRec(MachineInstr *MI, unsigned SrcReg, unsigned DstReg) {
81 static unsigned getBaseIndex(unsigned index) {
82 return index - (index % InstrSlots::NUM);
84 static unsigned getBoundaryIndex(unsigned index) {
85 return getBaseIndex(index + InstrSlots::NUM - 1);
87 static unsigned getLoadIndex(unsigned index) {
88 return getBaseIndex(index) + InstrSlots::LOAD;
90 static unsigned getUseIndex(unsigned index) {
91 return getBaseIndex(index) + InstrSlots::USE;
93 static unsigned getDefIndex(unsigned index) {
94 return getBaseIndex(index) + InstrSlots::DEF;
96 static unsigned getStoreIndex(unsigned index) {
97 return getBaseIndex(index) + InstrSlots::STORE;
100 typedef Reg2IntervalMap::iterator iterator;
101 typedef Reg2IntervalMap::const_iterator const_iterator;
102 const_iterator begin() const { return r2iMap_.begin(); }
103 const_iterator end() const { return r2iMap_.end(); }
104 iterator begin() { return r2iMap_.begin(); }
105 iterator end() { return r2iMap_.end(); }
106 unsigned getNumIntervals() const { return r2iMap_.size(); }
108 LiveInterval &getInterval(unsigned reg) {
109 Reg2IntervalMap::iterator I = r2iMap_.find(reg);
110 assert(I != r2iMap_.end() && "Interval does not exist for register");
114 const LiveInterval &getInterval(unsigned reg) const {
115 Reg2IntervalMap::const_iterator I = r2iMap_.find(reg);
116 assert(I != r2iMap_.end() && "Interval does not exist for register");
120 /// getMBBStartIdx - Return the base index of the first instruction in the
121 /// specified MachineBasicBlock.
122 unsigned getMBBStartIdx(MachineBasicBlock *MBB) const {
123 return getMBBStartIdx(MBB->getNumber());
126 unsigned getMBBStartIdx(unsigned MBBNo) const {
127 assert(MBBNo < MBB2IdxMap.size() && "Invalid MBB number!");
128 return MBB2IdxMap[MBBNo];
131 /// getInstructionIndex - returns the base index of instr
132 unsigned getInstructionIndex(MachineInstr* instr) const {
133 Mi2IndexMap::const_iterator it = mi2iMap_.find(instr);
134 assert(it != mi2iMap_.end() && "Invalid instruction!");
138 /// getInstructionFromIndex - given an index in any slot of an
139 /// instruction return a pointer the instruction
140 MachineInstr* getInstructionFromIndex(unsigned index) const {
141 index /= InstrSlots::NUM; // convert index to vector index
142 assert(index < i2miMap_.size() &&
143 "index does not correspond to an instruction");
144 return i2miMap_[index];
147 std::vector<LiveInterval*> addIntervalsForSpills(const LiveInterval& i,
151 /// CreateNewLiveInterval - Create a new live interval with the given live
152 /// ranges. The new live interval will have an infinite spill weight.
153 LiveInterval &CreateNewLiveInterval(const LiveInterval *LI,
154 const std::vector<LiveRange> &LRs);
156 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
157 virtual void releaseMemory();
159 /// runOnMachineFunction - pass entry point
160 virtual bool runOnMachineFunction(MachineFunction&);
162 /// print - Implement the dump method.
163 virtual void print(std::ostream &O, const Module* = 0) const;
164 void print(std::ostream *O, const Module* M = 0) const {
169 /// RemoveMachineInstrFromMaps - This marks the specified machine instr as
171 void RemoveMachineInstrFromMaps(MachineInstr *MI) {
172 // remove index -> MachineInstr and
173 // MachineInstr -> index mappings
174 Mi2IndexMap::iterator mi2i = mi2iMap_.find(MI);
175 if (mi2i != mi2iMap_.end()) {
176 i2miMap_[mi2i->second/InstrSlots::NUM] = 0;
177 mi2iMap_.erase(mi2i);
181 /// computeIntervals - Compute live intervals.
182 void computeIntervals();
184 /// joinIntervals - join compatible live intervals
185 void joinIntervals();
187 /// CopyCoallesceInMBB - Coallsece copies in the specified MBB, putting
188 /// copies that cannot yet be coallesced into the "TryAgain" list.
189 void CopyCoallesceInMBB(MachineBasicBlock *MBB,
190 std::vector<CopyRec> &TryAgain);
191 /// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
192 /// which are the src/dst of the copy instruction CopyMI. This returns true
193 /// if the copy was successfully coallesced away, or if it is never possible
194 /// to coallesce these this copy, due to register constraints. It returns
195 /// false if it is not currently possible to coallesce this interval, but
196 /// it may be possible if other things get coallesced.
197 bool JoinCopy(MachineInstr *CopyMI, unsigned SrcReg, unsigned DstReg);
199 /// JoinIntervals - Attempt to join these two intervals. On failure, this
200 /// returns false. Otherwise, if one of the intervals being joined is a
201 /// physreg, this method always canonicalizes DestInt to be it. The output
202 /// "SrcInt" will not have been modified, so we can use this information
203 /// below to update aliases.
204 bool JoinIntervals(LiveInterval &LHS, LiveInterval &RHS);
206 /// SimpleJoin - Attempt to join the specified interval into this one. The
207 /// caller of this method must guarantee that the RHS only contains a single
208 /// value number and that the RHS is not defined by a copy from this
209 /// interval. This returns false if the intervals are not joinable, or it
210 /// joins them and returns true.
211 bool SimpleJoin(LiveInterval &LHS, LiveInterval &RHS);
213 /// handleRegisterDef - update intervals for a register def
214 /// (calls handlePhysicalRegisterDef and
215 /// handleVirtualRegisterDef)
216 void handleRegisterDef(MachineBasicBlock *MBB,
217 MachineBasicBlock::iterator MI, unsigned MIIdx,
220 /// handleVirtualRegisterDef - update intervals for a virtual
222 void handleVirtualRegisterDef(MachineBasicBlock *MBB,
223 MachineBasicBlock::iterator MI,
225 LiveInterval& interval);
227 /// handlePhysicalRegisterDef - update intervals for a physical register
229 void handlePhysicalRegisterDef(MachineBasicBlock* mbb,
230 MachineBasicBlock::iterator mi,
232 LiveInterval &interval,
235 /// Return true if the two specified registers belong to different
236 /// register classes. The registers may be either phys or virt regs.
237 bool differingRegisterClasses(unsigned RegA, unsigned RegB) const;
240 bool AdjustCopiesBackFrom(LiveInterval &IntA, LiveInterval &IntB,
241 MachineInstr *CopyMI);
243 bool overlapsAliases(const LiveInterval *lhs,
244 const LiveInterval *rhs) const;
246 static LiveInterval createInterval(unsigned Reg);
248 LiveInterval &getOrCreateInterval(unsigned reg) {
249 Reg2IntervalMap::iterator I = r2iMap_.find(reg);
250 if (I == r2iMap_.end())
251 I = r2iMap_.insert(I, std::make_pair(reg, createInterval(reg)));
255 /// rep - returns the representative of this register
256 unsigned rep(unsigned Reg) {
257 unsigned Rep = r2rMap_[Reg];
259 return r2rMap_[Reg] = rep(Rep);
263 void printRegName(unsigned reg) const;
266 } // End llvm namespace