1 //===-- llvm/CodeGen/VirtRegMap.h - Virtual Register Map -*- C++ -*--------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // 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/ADT/IndexedMap.h" 21 #include "llvm/CodeGen/MachineFunctionPass.h" 22 #include "llvm/Target/TargetRegisterInfo.h" 23 24 namespace llvm { 25 class MachineInstr; 26 class MachineFunction; 27 class MachineRegisterInfo; 28 class TargetInstrInfo; 29 class raw_ostream; 30 class SlotIndexes; 31 32 class VirtRegMap : public MachineFunctionPass { 33 public: 34 enum { 35 NO_PHYS_REG = 0, 36 NO_STACK_SLOT = (1L << 30)-1, 37 MAX_STACK_SLOT = (1L << 18)-1 38 }; 39 40 private: 41 MachineRegisterInfo *MRI; 42 const TargetInstrInfo *TII; 43 const TargetRegisterInfo *TRI; 44 MachineFunction *MF; 45 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 53 /// Virt2StackSlotMap - This is virtual register to stack slot 54 /// mapping. Each spilled virtual register has an entry in it 55 /// which corresponds to the stack slot this register is spilled 56 /// at. 57 IndexedMap<int, VirtReg2IndexFunctor> Virt2StackSlotMap; 58 59 /// Virt2SplitMap - This is virtual register to splitted virtual register 60 /// mapping. 61 IndexedMap<unsigned, VirtReg2IndexFunctor> Virt2SplitMap; 62 63 /// createSpillSlot - Allocate a spill slot for RC from MFI. 64 unsigned createSpillSlot(const TargetRegisterClass *RC); 65 66 VirtRegMap(const VirtRegMap&) = delete; 67 void operator=(const VirtRegMap&) = delete; 68 69 public: 70 static char ID; 71 VirtRegMap() : MachineFunctionPass(ID), Virt2PhysMap(NO_PHYS_REG), 72 Virt2StackSlotMap(NO_STACK_SLOT), Virt2SplitMap(0) { } 73 bool runOnMachineFunction(MachineFunction &MF) override; 74 75 void getAnalysisUsage(AnalysisUsage &AU) const override { 76 AU.setPreservesAll(); 77 MachineFunctionPass::getAnalysisUsage(AU); 78 } 79 80 MachineFunction &getMachineFunction() const { 81 assert(MF && "getMachineFunction called before runOnMachineFunction"); 82 return *MF; 83 } 84 85 MachineRegisterInfo &getRegInfo() const { return *MRI; } 86 const TargetRegisterInfo &getTargetRegInfo() const { return *TRI; } 87 88 void grow(); 89 90 /// @brief returns true if the specified virtual register is 91 /// mapped to a physical register 92 bool hasPhys(unsigned virtReg) const { 93 return getPhys(virtReg) != NO_PHYS_REG; 94 } 95 96 /// @brief returns the physical register mapped to the specified 97 /// virtual register 98 unsigned getPhys(unsigned virtReg) const { 99 assert(TargetRegisterInfo::isVirtualRegister(virtReg)); 100 return Virt2PhysMap[virtReg]; 101 } 102 103 /// @brief creates a mapping for the specified virtual register to 104 /// the specified physical register 105 void assignVirt2Phys(unsigned virtReg, MCPhysReg physReg); 106 107 /// @brief clears the specified virtual register's, physical 108 /// register mapping 109 void clearVirt(unsigned virtReg) { 110 assert(TargetRegisterInfo::isVirtualRegister(virtReg)); 111 assert(Virt2PhysMap[virtReg] != NO_PHYS_REG && 112 "attempt to clear a not assigned virtual register"); 113 Virt2PhysMap[virtReg] = NO_PHYS_REG; 114 } 115 116 /// @brief clears all virtual to physical register mappings 117 void clearAllVirt() { 118 Virt2PhysMap.clear(); 119 grow(); 120 } 121 122 /// @brief returns true if VirtReg is assigned to its preferred physreg. 123 bool hasPreferredPhys(unsigned VirtReg); 124 125 /// @brief returns true if VirtReg has a known preferred register. 126 /// This returns false if VirtReg has a preference that is a virtual 127 /// register that hasn't been assigned yet. 128 bool hasKnownPreference(unsigned VirtReg); 129 130 /// @brief records virtReg is a split live interval from SReg. 131 void setIsSplitFromReg(unsigned virtReg, unsigned SReg) { 132 Virt2SplitMap[virtReg] = SReg; 133 } 134 135 /// @brief returns the live interval virtReg is split from. 136 unsigned getPreSplitReg(unsigned virtReg) const { 137 return Virt2SplitMap[virtReg]; 138 } 139 140 /// getOriginal - Return the original virtual register that VirtReg descends 141 /// from through splitting. 142 /// A register that was not created by splitting is its own original. 143 /// This operation is idempotent. 144 unsigned getOriginal(unsigned VirtReg) const { 145 unsigned Orig = getPreSplitReg(VirtReg); 146 return Orig ? Orig : VirtReg; 147 } 148 149 /// @brief returns true if the specified virtual register is not 150 /// mapped to a stack slot or rematerialized. 151 bool isAssignedReg(unsigned virtReg) const { 152 if (getStackSlot(virtReg) == NO_STACK_SLOT) 153 return true; 154 // Split register can be assigned a physical register as well as a 155 // stack slot or remat id. 156 return (Virt2SplitMap[virtReg] && Virt2PhysMap[virtReg] != NO_PHYS_REG); 157 } 158 159 /// @brief returns the stack slot mapped to the specified virtual 160 /// register 161 int getStackSlot(unsigned virtReg) const { 162 assert(TargetRegisterInfo::isVirtualRegister(virtReg)); 163 return Virt2StackSlotMap[virtReg]; 164 } 165 166 /// @brief create a mapping for the specifed virtual register to 167 /// the next available stack slot 168 int assignVirt2StackSlot(unsigned virtReg); 169 /// @brief create a mapping for the specified virtual register to 170 /// the specified stack slot 171 void assignVirt2StackSlot(unsigned virtReg, int frameIndex); 172 173 void print(raw_ostream &OS, const Module* M = nullptr) const override; 174 void dump() const; 175 }; 176 177 inline raw_ostream &operator<<(raw_ostream &OS, const VirtRegMap &VRM) { 178 VRM.print(OS); 179 return OS; 180 } 181 } // End llvm namespace 182 183 #endif 184
