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     class VirtRegMap;
  32
  33     struct Interval {
  34         typedef std::pair<unsigned, unsigned> Range;
  35         typedef std::vector<Range> Ranges;
  36         unsigned reg;   // the register of this interval
  37         float weight;   // weight of this interval:
  38                         //     (number of uses *10^loopDepth)
  39         Ranges ranges;  // the ranges in which this register is live
  40
  41         explicit Interval(unsigned r);
  42
  43         bool empty() const { return ranges.empty(); }
  44
  45         bool spilled() const;
  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         bool operator<(const Interval& other) const {
  70             return start() < other.start();
  71         }
  72
  73         bool operator==(const Interval& other) const {
  74             return reg == other.reg;
  75         }
  76
  77     private:
  78         Ranges::iterator mergeRangesForward(Ranges::iterator it);
  79         Ranges::iterator mergeRangesBackward(Ranges::iterator it);
  80     };
  81
  82     std::ostream& operator<<(std::ostream& os, const Interval& li);
  83
  84     class LiveIntervals : public MachineFunctionPass
  85     {
  86     public:
  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         struct InstrSlots
 116         {
 117             enum {
 118                 LOAD  = 0,
 119                 USE   = 1,
 120                 DEF   = 2,
 121                 STORE = 3,
 122                 NUM   = 4,
 123             };
 124         };
 125
 126         static unsigned getBaseIndex(unsigned index) {
 127             return index - (index % InstrSlots::NUM);
 128         }
 129         static unsigned getBoundaryIndex(unsigned index) {
 130             return getBaseIndex(index + InstrSlots::NUM - 1);
 131         }
 132         static unsigned getLoadIndex(unsigned index) {
 133             return getBaseIndex(index) + InstrSlots::LOAD;
 134         }
 135         static unsigned getUseIndex(unsigned index) {
 136             return getBaseIndex(index) + InstrSlots::USE;
 137         }
 138         static unsigned getDefIndex(unsigned index) {
 139             return getBaseIndex(index) + InstrSlots::DEF;
 140         }
 141         static unsigned getStoreIndex(unsigned index) {
 142             return getBaseIndex(index) + InstrSlots::STORE;
 143         }
 144
 145         virtual void getAnalysisUsage(AnalysisUsage &AU) const;
 146         virtual void releaseMemory();
 147
 148         /// runOnMachineFunction - pass entry point
 149         virtual bool runOnMachineFunction(MachineFunction&);
 150
 151         Interval& getInterval(unsigned reg) {
 152             assert(r2iMap_.count(reg)&& "Interval does not exist for register");
 153             return *r2iMap_.find(reg)->second;
 154         }
 155
 156         /// getInstructionIndex - returns the base index of instr
 157         unsigned getInstructionIndex(MachineInstr* instr) const;
 158
 159         /// getInstructionFromIndex - given an index in any slot of an
 160         /// instruction return a pointer the instruction
 161         MachineInstr* getInstructionFromIndex(unsigned index) const;
 162
 163         Intervals& getIntervals() { return intervals_; }
 164
 165         std::vector<Interval*> addIntervalsForSpills(const Interval& i,
 166                                                      VirtRegMap& vrm,
 167                                                      int slot);
 168
 169     private:
 170         /// computeIntervals - compute live intervals
 171         void computeIntervals();
 172
 173         /// joinIntervals - join compatible live intervals
 174         void joinIntervals();
 175
 176         /// handleRegisterDef - update intervals for a register def
 177         /// (calls handlePhysicalRegisterDef and
 178         /// handleVirtualRegisterDef)
 179         void handleRegisterDef(MachineBasicBlock* mbb,
 180                                MachineBasicBlock::iterator mi,
 181                                unsigned reg);
 182
 183         /// handleVirtualRegisterDef - update intervals for a virtual
 184         /// register def
 185         void handleVirtualRegisterDef(MachineBasicBlock* mbb,
 186                                       MachineBasicBlock::iterator mi,
 187                                       Interval& interval);
 188
 189         /// handlePhysicalRegisterDef - update intervals for a
 190         /// physical register def
 191         void handlePhysicalRegisterDef(MachineBasicBlock* mbb,
 192                                        MachineBasicBlock::iterator mi,
 193                                        Interval& interval);
 194
 195         bool overlapsAliases(const Interval& lhs, const Interval& rhs) const;
 196
 197
 198         Interval& getOrCreateInterval(unsigned reg);
 199
 200         /// rep - returns the representative of this register
 201         unsigned rep(unsigned reg);
 202
 203         void printRegName(unsigned reg) const;
 204     };
 205
 206 } // End llvm namespace
 207
 208 #endif