lib/CodeGen/LiveIntervalAnalysis.h

   1 //===-- llvm/CodeGen/LiveInterval.h - Live Interval Analysis ----*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   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.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the LiveInterval analysis pass.  Given some
  11 // numbering of each the machine instructions (in this implemention
  12 // depth-first order) an interval [i, j) is said to be a live interval
  13 // for register v if there is no instruction with number j' > j such
  14 // that v is live at j' abd there is no instruction with number i' < i
  15 // such that v is live at i'. In this implementation intervals can
  16 // have holes, i.e. an interval might look like [1,20), [50,65),
  17 // [1000,1001)
  18 //
  19 //===----------------------------------------------------------------------===//
  20
  21 #ifndef LLVM_CODEGEN_LIVEINTERVALS_H
  22 #define LLVM_CODEGEN_LIVEINTERVALS_H
  23
  24 #include "llvm/CodeGen/MachineFunctionPass.h"
  25 #include <list>
  26
  27 namespace llvm {
  28
  29     class LiveVariables;
  30     class MRegisterInfo;
  31
  32     class LiveIntervals : public MachineFunctionPass
  33     {
  34     public:
  35         struct Interval {
  36             typedef std::pair<unsigned, unsigned> Range;
  37             typedef std::vector<Range> Ranges;
  38             unsigned reg;   // the register of this interval
  39             float weight;   // weight of this interval (number of uses
  40                             // * 10^loopDepth)
  41             Ranges ranges;  // the ranges in which this register is live
  42
  43             Interval(unsigned r);
  44
  45             bool empty() const { return ranges.empty(); }
  46
  47             unsigned start() const {
  48                 assert(!empty() && "empty interval for register");
  49                 return ranges.front().first;
  50             }
  51
  52             unsigned end() const {
  53                 assert(!empty() && "empty interval for register");
  54                 return ranges.back().second;
  55             }
  56
  57             bool expiredAt(unsigned index) const {
  58                 return end() <= (index + 1);
  59             }
  60
  61             bool liveAt(unsigned index) const;
  62
  63             bool overlaps(const Interval& other) const;
  64
  65             void addRange(unsigned start, unsigned end);
  66
  67             void join(const Interval& other);
  68
  69         private:
  70             Ranges::iterator mergeRangesForward(Ranges::iterator it);
  71
  72             Ranges::iterator mergeRangesBackward(Ranges::iterator it);
  73         };
  74
  75         struct StartPointComp {
  76             bool operator()(const Interval& lhs, const Interval& rhs) {
  77                 return lhs.ranges.front().first < rhs.ranges.front().first;
  78             }
  79         };
  80
  81         struct EndPointComp {
  82             bool operator()(const Interval& lhs, const Interval& rhs) {
  83                 return lhs.ranges.back().second < rhs.ranges.back().second;
  84             }
  85         };
  86
  87         typedef std::list<Interval> Intervals;
  88
  89     private:
  90         MachineFunction* mf_;
  91         const TargetMachine* tm_;
  92         const MRegisterInfo* mri_;
  93         MachineBasicBlock* currentMbb_;
  94         MachineBasicBlock::iterator currentInstr_;
  95         LiveVariables* lv_;
  96
  97         typedef std::map<unsigned, MachineBasicBlock*> MbbIndex2MbbMap;
  98         MbbIndex2MbbMap mbbi2mbbMap_;
  99
 100         typedef std::map<MachineInstr*, unsigned> Mi2IndexMap;
 101         Mi2IndexMap mi2iMap_;
 102
 103         typedef std::vector<MachineInstr*> Index2MiMap;
 104         Index2MiMap i2miMap_;
 105
 106         typedef std::map<unsigned, Intervals::iterator> Reg2IntervalMap;
 107         Reg2IntervalMap r2iMap_;
 108
 109         typedef std::map<unsigned, unsigned> Reg2RegMap;
 110         Reg2RegMap r2rMap_;
 111
 112         Intervals intervals_;
 113
 114     public:
 115         virtual void getAnalysisUsage(AnalysisUsage &AU) const;
 116         virtual void releaseMemory();
 117
 118         /// runOnMachineFunction - pass entry point
 119         virtual bool runOnMachineFunction(MachineFunction&);
 120
 121         Interval& getInterval(unsigned reg) {
 122             assert(r2iMap_.count(reg)&& "Interval does not exist for register");
 123             return *r2iMap_.find(reg)->second;
 124         }
 125
 126         unsigned getInstructionIndex(MachineInstr* instr) const;
 127
 128         MachineInstr* getInstructionFromIndex(unsigned index) const;
 129
 130         Intervals& getIntervals() { return intervals_; }
 131
 132         void updateSpilledInterval(Interval& i);
 133
 134     private:
 135         /// computeIntervals - compute live intervals
 136         void computeIntervals();
 137
 138         /// joinIntervals - join compatible live intervals
 139         void joinIntervals();
 140
 141         /// handleRegisterDef - update intervals for a register def
 142         /// (calls handlePhysicalRegisterDef and
 143         /// handleVirtualRegisterDef)
 144         void handleRegisterDef(MachineBasicBlock* mbb,
 145                                MachineBasicBlock::iterator mi,
 146                                unsigned reg);
 147
 148         /// handleVirtualRegisterDef - update intervals for a virtual
 149         /// register def
 150         void handleVirtualRegisterDef(MachineBasicBlock* mbb,
 151                                       MachineBasicBlock::iterator mi,
 152                                       unsigned reg);
 153
 154         /// handlePhysicalRegisterDef - update intervals for a
 155         /// physical register def
 156         void handlePhysicalRegisterDef(MachineBasicBlock* mbb,
 157                                        MachineBasicBlock::iterator mi,
 158                                        unsigned reg);
 159
 160         bool overlapsAliases(const Interval& lhs, const Interval& rhs) const;
 161
 162         /// rep - returns the representative of this register
 163         unsigned rep(unsigned reg);
 164
 165         void printRegName(unsigned reg) const;
 166     };
 167
 168     inline bool operator==(const LiveIntervals::Interval& lhs,
 169                            const LiveIntervals::Interval& rhs) {
 170         return lhs.reg == rhs.reg;
 171     }
 172
 173     std::ostream& operator<<(std::ostream& os,
 174                              const LiveIntervals::Interval& li);
 175
 176 } // End llvm namespace
 177
 178 #endif