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 <list>
  28 #include <map>
  29
  30 namespace llvm {
  31
  32     class LiveVariables;
  33     class MRegisterInfo;
  34
  35     class LiveIntervals : public MachineFunctionPass
  36     {
  37     public:
  38         struct Interval {
  39             typedef std::pair<unsigned, unsigned> Range;
  40             typedef std::vector<Range> Ranges;
  41             unsigned reg;   // the register of this interval
  42             unsigned hint;
  43             float weight;   // weight of this interval (number of uses
  44                             // * 10^loopDepth)
  45             Ranges ranges;  // the ranges this register is valid
  46
  47             Interval(unsigned r);
  48
  49             unsigned start() const {
  50                 assert(!ranges.empty() && "empty interval for register");
  51                 return ranges.front().first;
  52             }
  53
  54             unsigned end() const {
  55                 assert(!ranges.empty() && "empty interval for register");
  56                 return ranges.back().second;
  57             }
  58
  59             bool expiredAt(unsigned index) const {
  60                 return end() <= index;
  61             }
  62
  63             bool liveAt(unsigned index) const;
  64
  65             bool overlaps(const Interval& other) const;
  66
  67             void addRange(unsigned start, unsigned end);
  68
  69         private:
  70             void mergeRangesForward(Ranges::iterator it);
  71
  72             void 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         typedef std::vector<MachineBasicBlock*> MachineBasicBlockPtrs;
  89
  90     private:
  91         MachineFunction* mf_;
  92         const TargetMachine* tm_;
  93         const MRegisterInfo* mri_;
  94         MachineBasicBlock* currentMbb_;
  95         MachineBasicBlock::iterator currentInstr_;
  96         LiveVariables* lv_;
  97
  98         typedef std::map<unsigned, MachineBasicBlock*> MbbIndex2MbbMap;
  99         MbbIndex2MbbMap mbbi2mbbMap_;
 100
 101         typedef std::map<MachineInstr*, unsigned> Mi2IndexMap;
 102         Mi2IndexMap mi2iMap_;
 103
 104         typedef std::map<unsigned, Intervals::iterator> Reg2IntervalMap;
 105         Reg2IntervalMap r2iMap_;
 106
 107         Intervals intervals_;
 108
 109     public:
 110         virtual void getAnalysisUsage(AnalysisUsage &AU) const;
 111         Intervals& getIntervals() { return intervals_; }
 112         MachineBasicBlockPtrs getOrderedMachineBasicBlockPtrs() const {
 113             MachineBasicBlockPtrs result;
 114             for (MbbIndex2MbbMap::const_iterator
 115                      it = mbbi2mbbMap_.begin(), itEnd = mbbi2mbbMap_.end();
 116                  it != itEnd; ++it) {
 117                 result.push_back(it->second);
 118             }
 119             return result;
 120         }
 121
 122     private:
 123         /// runOnMachineFunction - pass entry point
 124         bool runOnMachineFunction(MachineFunction&);
 125
 126         /// computeIntervals - compute live intervals
 127         void computeIntervals();
 128
 129
 130         /// handleRegisterDef - update intervals for a register def
 131         /// (calls handlePhysicalRegisterDef and
 132         /// handleVirtualRegisterDef)
 133         void handleRegisterDef(MachineBasicBlock* mbb,
 134                                MachineBasicBlock::iterator mi,
 135                                unsigned reg);
 136
 137         /// handleVirtualRegisterDef - update intervals for a virtual
 138         /// register def
 139         void handleVirtualRegisterDef(MachineBasicBlock* mbb,
 140                                       MachineBasicBlock::iterator mi,
 141                                       unsigned reg);
 142
 143         /// handlePhysicalRegisterDef - update intervals for a
 144         /// physical register def
 145         void handlePhysicalRegisterDef(MachineBasicBlock* mbb,
 146                                        MachineBasicBlock::iterator mi,
 147                                        unsigned reg);
 148
 149         unsigned getInstructionIndex(MachineInstr* instr) const;
 150
 151         void printRegName(unsigned reg) const;
 152     };
 153
 154     inline bool operator==(const LiveIntervals::Interval& lhs,
 155                            const LiveIntervals::Interval& rhs) {
 156         return lhs.reg == rhs.reg;
 157     }
 158
 159     std::ostream& operator<<(std::ostream& os,
 160                              const LiveIntervals::Interval& li);
 161
 162 } // End llvm namespace
 163
 164 #endif