LLVM API Documentation
00001 //===-- llvm/CodeGen/VirtRegMap.h - Virtual Register Map -*- C++ -*--------===// 00002 // 00003 // The LLVM Compiler Infrastructure 00004 // 00005 // This file was developed by the LLVM research group and is distributed under 00006 // the University of Illinois Open Source License. See LICENSE.TXT for details. 00007 // 00008 //===----------------------------------------------------------------------===// 00009 // 00010 // This file implements a virtual register map. This maps virtual registers to 00011 // physical registers and virtual registers to stack slots. It is created and 00012 // updated by a register allocator and then used by a machine code rewriter that 00013 // adds spill code and rewrites virtual into physical register references. 00014 // 00015 //===----------------------------------------------------------------------===// 00016 00017 #ifndef LLVM_CODEGEN_VIRTREGMAP_H 00018 #define LLVM_CODEGEN_VIRTREGMAP_H 00019 00020 #include "llvm/Target/MRegisterInfo.h" 00021 #include "llvm/ADT/DenseMap.h" 00022 #include <map> 00023 00024 namespace llvm { 00025 class MachineInstr; 00026 00027 class VirtRegMap { 00028 public: 00029 enum ModRef { isRef = 1, isMod = 2, isModRef = 3 }; 00030 typedef std::multimap<MachineInstr*, 00031 std::pair<unsigned, ModRef> > MI2VirtMapTy; 00032 00033 private: 00034 MachineFunction &MF; 00035 /// Virt2PhysMap - This is a virtual to physical register 00036 /// mapping. Each virtual register is required to have an entry in 00037 /// it; even spilled virtual registers (the register mapped to a 00038 /// spilled register is the temporary used to load it from the 00039 /// stack). 00040 DenseMap<unsigned, VirtReg2IndexFunctor> Virt2PhysMap; 00041 /// Virt2StackSlotMap - This is virtual register to stack slot 00042 /// mapping. Each spilled virtual register has an entry in it 00043 /// which corresponds to the stack slot this register is spilled 00044 /// at. 00045 DenseMap<int, VirtReg2IndexFunctor> Virt2StackSlotMap; 00046 /// MI2VirtMap - This is MachineInstr to virtual register 00047 /// mapping. In the case of memory spill code being folded into 00048 /// instructions, we need to know which virtual register was 00049 /// read/written by this instruction. 00050 MI2VirtMapTy MI2VirtMap; 00051 00052 VirtRegMap(const VirtRegMap&); // DO NOT IMPLEMENT 00053 void operator=(const VirtRegMap&); // DO NOT IMPLEMENT 00054 00055 enum { 00056 NO_PHYS_REG = 0, 00057 NO_STACK_SLOT = ~0 >> 1 00058 }; 00059 00060 public: 00061 VirtRegMap(MachineFunction &mf) 00062 : MF(mf), Virt2PhysMap(NO_PHYS_REG), Virt2StackSlotMap(NO_STACK_SLOT) { 00063 grow(); 00064 } 00065 00066 void grow(); 00067 00068 /// @brief returns true if the specified virtual register is 00069 /// mapped to a physical register 00070 bool hasPhys(unsigned virtReg) const { 00071 return getPhys(virtReg) != NO_PHYS_REG; 00072 } 00073 00074 /// @brief returns the physical register mapped to the specified 00075 /// virtual register 00076 unsigned getPhys(unsigned virtReg) const { 00077 assert(MRegisterInfo::isVirtualRegister(virtReg)); 00078 return Virt2PhysMap[virtReg]; 00079 } 00080 00081 /// @brief creates a mapping for the specified virtual register to 00082 /// the specified physical register 00083 void assignVirt2Phys(unsigned virtReg, unsigned physReg) { 00084 assert(MRegisterInfo::isVirtualRegister(virtReg) && 00085 MRegisterInfo::isPhysicalRegister(physReg)); 00086 assert(Virt2PhysMap[virtReg] == NO_PHYS_REG && 00087 "attempt to assign physical register to already mapped " 00088 "virtual register"); 00089 Virt2PhysMap[virtReg] = physReg; 00090 } 00091 00092 /// @brief clears the specified virtual register's, physical 00093 /// register mapping 00094 void clearVirt(unsigned virtReg) { 00095 assert(MRegisterInfo::isVirtualRegister(virtReg)); 00096 assert(Virt2PhysMap[virtReg] != NO_PHYS_REG && 00097 "attempt to clear a not assigned virtual register"); 00098 Virt2PhysMap[virtReg] = NO_PHYS_REG; 00099 } 00100 00101 /// @brief clears all virtual to physical register mappings 00102 void clearAllVirt() { 00103 Virt2PhysMap.clear(); 00104 grow(); 00105 } 00106 00107 /// @brief returns true is the specified virtual register is 00108 /// mapped to a stack slot 00109 bool hasStackSlot(unsigned virtReg) const { 00110 return getStackSlot(virtReg) != NO_STACK_SLOT; 00111 } 00112 00113 /// @brief returns the stack slot mapped to the specified virtual 00114 /// register 00115 int getStackSlot(unsigned virtReg) const { 00116 assert(MRegisterInfo::isVirtualRegister(virtReg)); 00117 return Virt2StackSlotMap[virtReg]; 00118 } 00119 00120 /// @brief create a mapping for the specifed virtual register to 00121 /// the next available stack slot 00122 int assignVirt2StackSlot(unsigned virtReg); 00123 /// @brief create a mapping for the specified virtual register to 00124 /// the specified stack slot 00125 void assignVirt2StackSlot(unsigned virtReg, int frameIndex); 00126 00127 /// @brief Updates information about the specified virtual register's value 00128 /// folded into newMI machine instruction. The OpNum argument indicates the 00129 /// operand number of OldMI that is folded. 00130 void virtFolded(unsigned VirtReg, MachineInstr *OldMI, unsigned OpNum, 00131 MachineInstr *NewMI); 00132 00133 /// @brief returns the virtual registers' values folded in memory 00134 /// operands of this instruction 00135 std::pair<MI2VirtMapTy::const_iterator, MI2VirtMapTy::const_iterator> 00136 getFoldedVirts(MachineInstr* MI) const { 00137 return MI2VirtMap.equal_range(MI); 00138 } 00139 00140 void print(std::ostream &OS) const; 00141 void dump() const; 00142 }; 00143 00144 inline std::ostream &operator<<(std::ostream &OS, const VirtRegMap &VRM) { 00145 VRM.print(OS); 00146 return OS; 00147 } 00148 00149 /// Spiller interface: Implementations of this interface assign spilled 00150 /// virtual registers to stack slots, rewriting the code. 00151 struct Spiller { 00152 virtual ~Spiller(); 00153 virtual bool runOnMachineFunction(MachineFunction &MF, 00154 const VirtRegMap &VRM) = 0; 00155 }; 00156 00157 /// createSpiller - Create an return a spiller object, as specified on the 00158 /// command line. 00159 Spiller* createSpiller(); 00160 00161 } // End llvm namespace 00162 00163 #endif