lib/CodeGen/VirtRegMap.h

   1 //===-- llvm/CodeGen/VirtRegMap.h - Virtual Register Map -*- 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 a virtual register map. This maps virtual registers to
  11 // physical registers and virtual registers to stack slots. It is created and
  12 // updated by a register allocator and then used by a machine code rewriter that
  13 // adds spill code and rewrites virtual into physical register references.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #ifndef LLVM_CODEGEN_VIRTREGMAP_H
  18 #define LLVM_CODEGEN_VIRTREGMAP_H
  19
  20 #include "llvm/Target/MRegisterInfo.h"
  21 #include "llvm/ADT/BitVector.h"
  22 #include "llvm/ADT/IndexedMap.h"
  23 #include "llvm/Support/Streams.h"
  24 #include <map>
  25
  26 namespace llvm {
  27   class MachineInstr;
  28   class TargetInstrInfo;
  29
  30   class VirtRegMap {
  31   public:
  32     enum {
  33       NO_PHYS_REG = 0,
  34       NO_STACK_SLOT = (1L << 30)-1,
  35       MAX_STACK_SLOT = (1L << 18)-1
  36     };
  37
  38     enum ModRef { isRef = 1, isMod = 2, isModRef = 3 };
  39     typedef std::multimap<MachineInstr*,
  40                           std::pair<unsigned, ModRef> > MI2VirtMapTy;
  41
  42   private:
  43     const TargetInstrInfo &TII;
  44
  45     MachineFunction &MF;
  46     /// Virt2PhysMap - This is a virtual to physical register
  47     /// mapping. Each virtual register is required to have an entry in
  48     /// it; even spilled virtual registers (the register mapped to a
  49     /// spilled register is the temporary used to load it from the
  50     /// stack).
  51     IndexedMap<unsigned, VirtReg2IndexFunctor> Virt2PhysMap;
  52     /// Virt2StackSlotMap - This is virtual register to stack slot
  53     /// mapping. Each spilled virtual register has an entry in it
  54     /// which corresponds to the stack slot this register is spilled
  55     /// at.
  56     IndexedMap<int, VirtReg2IndexFunctor> Virt2StackSlotMap;
  57     /// MI2VirtMap - This is MachineInstr to virtual register
  58     /// mapping. In the case of memory spill code being folded into
  59     /// instructions, we need to know which virtual register was
  60     /// read/written by this instruction.
  61     MI2VirtMapTy MI2VirtMap;
  62
  63     /// ReMatMap - This is virtual register to re-materialized instruction
  64     /// mapping. Each virtual register whose definition is going to be
  65     /// re-materialized has an entry in it.
  66     std::map<unsigned, const MachineInstr*> ReMatMap;
  67
  68     /// ReMatId - Instead of assigning a stack slot to a to be rematerialized
  69     /// virtual register, an unique id is being assigned. This keeps track of
  70     /// the highest id used so far. Note, this starts at (1<<18) to avoid
  71     /// conflicts with stack slot numbers.
  72     int ReMatId;
  73
  74     VirtRegMap(const VirtRegMap&);     // DO NOT IMPLEMENT
  75     void operator=(const VirtRegMap&); // DO NOT IMPLEMENT
  76
  77   public:
  78     VirtRegMap(MachineFunction &mf);
  79
  80     void grow();
  81
  82     /// @brief returns true if the specified virtual register is
  83     /// mapped to a physical register
  84     bool hasPhys(unsigned virtReg) const {
  85       return getPhys(virtReg) != NO_PHYS_REG;
  86     }
  87
  88     /// @brief returns the physical register mapped to the specified
  89     /// virtual register
  90     unsigned getPhys(unsigned virtReg) const {
  91       assert(MRegisterInfo::isVirtualRegister(virtReg));
  92       return Virt2PhysMap[virtReg];
  93     }
  94
  95     /// @brief creates a mapping for the specified virtual register to
  96     /// the specified physical register
  97     void assignVirt2Phys(unsigned virtReg, unsigned physReg) {
  98       assert(MRegisterInfo::isVirtualRegister(virtReg) &&
  99              MRegisterInfo::isPhysicalRegister(physReg));
 100       assert(Virt2PhysMap[virtReg] == NO_PHYS_REG &&
 101              "attempt to assign physical register to already mapped "
 102              "virtual register");
 103       Virt2PhysMap[virtReg] = physReg;
 104     }
 105
 106     /// @brief clears the specified virtual register's, physical
 107     /// register mapping
 108     void clearVirt(unsigned virtReg) {
 109       assert(MRegisterInfo::isVirtualRegister(virtReg));
 110       assert(Virt2PhysMap[virtReg] != NO_PHYS_REG &&
 111              "attempt to clear a not assigned virtual register");
 112       Virt2PhysMap[virtReg] = NO_PHYS_REG;
 113     }
 114
 115     /// @brief clears all virtual to physical register mappings
 116     void clearAllVirt() {
 117       Virt2PhysMap.clear();
 118       grow();
 119     }
 120
 121     /// @brief returns true is the specified virtual register is
 122     /// mapped to a stack slot
 123     bool hasStackSlot(unsigned virtReg) const {
 124       return getStackSlot(virtReg) != NO_STACK_SLOT;
 125     }
 126
 127     /// @brief returns the stack slot mapped to the specified virtual
 128     /// register
 129     int getStackSlot(unsigned virtReg) const {
 130       assert(MRegisterInfo::isVirtualRegister(virtReg));
 131       return Virt2StackSlotMap[virtReg];
 132     }
 133
 134     /// @brief create a mapping for the specifed virtual register to
 135     /// the next available stack slot
 136     int assignVirt2StackSlot(unsigned virtReg);
 137     /// @brief create a mapping for the specified virtual register to
 138     /// the specified stack slot
 139     void assignVirt2StackSlot(unsigned virtReg, int frameIndex);
 140
 141     /// @brief assign an unique re-materialization id to the specified
 142     /// virtual register.
 143     int assignVirtReMatId(unsigned virtReg);
 144
 145     /// @brief returns true if the specified virtual register is being
 146     /// re-materialized.
 147     bool isReMaterialized(unsigned virtReg) const {
 148       return ReMatMap.count(virtReg) != 0;
 149     }
 150
 151     /// @brief returns the original machine instruction being re-issued
 152     /// to re-materialize the specified virtual register.
 153     const MachineInstr *getReMaterializedMI(unsigned virtReg) {
 154       return ReMatMap[virtReg];
 155     }
 156
 157     /// @brief records the specified virtual register will be
 158     /// re-materialized and the original instruction which will be re-issed
 159     /// for this purpose.
 160     void setVirtIsReMaterialized(unsigned virtReg, MachineInstr *def) {
 161       ReMatMap[virtReg] = def;
 162     }
 163
 164     /// @brief Updates information about the specified virtual register's value
 165     /// folded into newMI machine instruction.  The OpNum argument indicates the
 166     /// operand number of OldMI that is folded.
 167     void virtFolded(unsigned VirtReg, MachineInstr *OldMI, unsigned OpNum,
 168                     MachineInstr *NewMI);
 169
 170     /// @brief returns the virtual registers' values folded in memory
 171     /// operands of this instruction
 172     std::pair<MI2VirtMapTy::const_iterator, MI2VirtMapTy::const_iterator>
 173     getFoldedVirts(MachineInstr* MI) const {
 174       return MI2VirtMap.equal_range(MI);
 175     }
 176
 177     /// RemoveFromFoldedVirtMap - If the specified machine instruction is in
 178     /// the folded instruction map, remove its entry from the map.
 179     void RemoveFromFoldedVirtMap(MachineInstr *MI) {
 180       MI2VirtMap.erase(MI);
 181     }
 182
 183     void print(std::ostream &OS) const;
 184     void print(std::ostream *OS) const { if (OS) print(*OS); }
 185     void dump() const;
 186   };
 187
 188   inline std::ostream *operator<<(std::ostream *OS, const VirtRegMap &VRM) {
 189     VRM.print(OS);
 190     return OS;
 191   }
 192   inline std::ostream &operator<<(std::ostream &OS, const VirtRegMap &VRM) {
 193     VRM.print(OS);
 194     return OS;
 195   }
 196
 197   /// Spiller interface: Implementations of this interface assign spilled
 198   /// virtual registers to stack slots, rewriting the code.
 199   struct Spiller {
 200     virtual ~Spiller();
 201     virtual bool runOnMachineFunction(MachineFunction &MF,
 202                                       VirtRegMap &VRM) = 0;
 203   };
 204
 205   /// createSpiller - Create an return a spiller object, as specified on the
 206   /// command line.
 207   Spiller* createSpiller();
 208
 209 } // End llvm namespace
 210
 211 #endif