include/llvm/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 "llvm/CodeGen/MachineBasicBlock.h"
  26 #include <iostream>
  27 #include <map>
  28
  29 namespace llvm {
  30
  31     class LiveVariables;
  32     class MRegisterInfo;
  33
  34     class LiveIntervals : public MachineFunctionPass
  35     {
  36     public:
  37         struct Interval {
  38             typedef std::pair<unsigned, unsigned> Range;
  39             typedef std::vector<Range> Ranges;
  40             unsigned reg;   // the register of this interval
  41             unsigned hint;
  42             float weight;   // weight of this interval (number of uses
  43                             // * 10^loopDepth)
  44             Ranges ranges;  // the ranges this register is valid
  45
  46             Interval(unsigned r);
  47
  48             unsigned start() const {
  49                 assert(!ranges.empty() && "empty interval for register");
  50                 return ranges.front().first;
  51             }
  52
  53             unsigned end() const {
  54                 assert(!ranges.empty() && "empty interval for register");
  55                 return ranges.back().second;
  56             }
  57
  58             bool expiredAt(unsigned index) const {
  59                 return end() <= index;
  60             }
  61
  62             bool liveAt(unsigned index) const;
  63
  64             bool overlaps(const Interval& other) const;
  65
  66             void addRange(unsigned start, unsigned end);
  67
  68         private:
  69             void mergeRangesForward(Ranges::iterator it);
  70
  71             void mergeRangesBackward(Ranges::iterator it);
  72         };
  73
  74         struct StartPointComp {
  75             bool operator()(const Interval& lhs, const Interval& rhs) {
  76                 return lhs.ranges.front().first < rhs.ranges.front().first;
  77             }
  78         };
  79
  80         struct EndPointComp {
  81             bool operator()(const Interval& lhs, const Interval& rhs) {
  82                 return lhs.ranges.back().second < rhs.ranges.back().second;
  83             }
  84         };
  85
  86         typedef std::vector<Interval> Intervals;
  87         typedef std::vector<MachineBasicBlock*> MachineBasicBlockPtrs;
  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::map<unsigned, unsigned> Reg2IntervalMap;
 104         Reg2IntervalMap r2iMap_;
 105
 106         Intervals intervals_;
 107
 108     public:
 109         virtual void getAnalysisUsage(AnalysisUsage &AU) const;
 110         Intervals& getIntervals() { return intervals_; }
 111         MachineBasicBlockPtrs getOrderedMachineBasicBlockPtrs() const {
 112             MachineBasicBlockPtrs result;
 113             for (MbbIndex2MbbMap::const_iterator
 114                      it = mbbi2mbbMap_.begin(), itEnd = mbbi2mbbMap_.end();
 115                  it != itEnd; ++it) {
 116                 result.push_back(it->second);
 117             }
 118             return result;
 119         }
 120
 121     private:
 122         /// runOnMachineFunction - pass entry point
 123         bool runOnMachineFunction(MachineFunction&);
 124
 125         /// computeIntervals - compute live intervals
 126         void computeIntervals();
 127
 128
 129         /// handleRegisterDef - update intervals for a register def
 130         /// (calls handlePhysicalRegisterDef and
 131         /// handleVirtualRegisterDef)
 132         void handleRegisterDef(MachineBasicBlock* mbb,
 133                                MachineBasicBlock::iterator mi,
 134                                unsigned reg);
 135
 136         /// handleVirtualRegisterDef - update intervals for a virtual
 137         /// register def
 138         void handleVirtualRegisterDef(MachineBasicBlock* mbb,
 139                                       MachineBasicBlock::iterator mi,
 140                                       unsigned reg);
 141
 142         /// handlePhysicalRegisterDef - update intervals for a
 143         /// physical register def
 144         void handlePhysicalRegisterDef(MachineBasicBlock* mbb,
 145                                        MachineBasicBlock::iterator mi,
 146                                        unsigned reg);
 147
 148         unsigned getInstructionIndex(MachineInstr* instr) const;
 149
 150         void printRegName(unsigned reg) const;
 151     };
 152
 153     inline bool operator==(const LiveIntervals::Interval& lhs,
 154                            const LiveIntervals::Interval& rhs) {
 155         return lhs.reg == rhs.reg;
 156     }
 157
 158     std::ostream& operator<<(std::ostream& os,
 159                              const LiveIntervals::Interval& li);
 160
 161 } // End llvm namespace
 162
 163 #endif