1 //===-- llvm/CodeGen/Register.h ---------------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLVM_CODEGEN_REGISTER_H 10 #define LLVM_CODEGEN_REGISTER_H 11 12 #include "llvm/MC/MCRegister.h" 13 #include <cassert> 14 15 namespace llvm { 16 17 /// Wrapper class representing virtual and physical registers. Should be passed 18 /// by value. 19 class Register { 20 unsigned Reg; 21 22 public: 23 constexpr Register(unsigned Val = 0): Reg(Val) {} 24 constexpr Register(MCRegister Val): Reg(Val) {} 25 26 // Register numbers can represent physical registers, virtual registers, and 27 // sometimes stack slots. The unsigned values are divided into these ranges: 28 // 29 // 0 Not a register, can be used as a sentinel. 30 // [1;2^30) Physical registers assigned by TableGen. 31 // [2^30;2^31) Stack slots. (Rarely used.) 32 // [2^31;2^32) Virtual registers assigned by MachineRegisterInfo. 33 // 34 // Further sentinels can be allocated from the small negative integers. 35 // DenseMapInfo<unsigned> uses -1u and -2u. 36 static_assert(std::numeric_limits<decltype(Reg)>::max() >= 0xFFFFFFFF, 37 "Reg isn't large enough to hold full range."); 38 39 /// isStackSlot - Sometimes it is useful the be able to store a non-negative 40 /// frame index in a variable that normally holds a register. isStackSlot() 41 /// returns true if Reg is in the range used for stack slots. 42 /// 43 /// Note that isVirtualRegister() and isPhysicalRegister() cannot handle stack 44 /// slots, so if a variable may contains a stack slot, always check 45 /// isStackSlot() first. 46 /// 47 static bool isStackSlot(unsigned Reg) { 48 return MCRegister::isStackSlot(Reg); 49 } 50 51 /// Compute the frame index from a register value representing a stack slot. 52 static int stackSlot2Index(unsigned Reg) { 53 assert(isStackSlot(Reg) && "Not a stack slot"); 54 return int(Reg - MCRegister::FirstStackSlot); 55 } 56 57 /// Convert a non-negative frame index to a stack slot register value. 58 static unsigned index2StackSlot(int FI) { 59 assert(FI >= 0 && "Cannot hold a negative frame index."); 60 return FI + MCRegister::FirstStackSlot; 61 } 62 63 /// Return true if the specified register number is in 64 /// the physical register namespace. 65 static bool isPhysicalRegister(unsigned Reg) { 66 return MCRegister::isPhysicalRegister(Reg); 67 } 68 69 /// Return true if the specified register number is in 70 /// the virtual register namespace. 71 static bool isVirtualRegister(unsigned Reg) { 72 assert(!isStackSlot(Reg) && "Not a register! Check isStackSlot() first."); 73 return Reg & MCRegister::VirtualRegFlag; 74 } 75 76 /// Convert a virtual register number to a 0-based index. 77 /// The first virtual register in a function will get the index 0. 78 static unsigned virtReg2Index(unsigned Reg) { 79 assert(isVirtualRegister(Reg) && "Not a virtual register"); 80 return Reg & ~MCRegister::VirtualRegFlag; 81 } 82 83 /// Convert a 0-based index to a virtual register number. 84 /// This is the inverse operation of VirtReg2IndexFunctor below. 85 static unsigned index2VirtReg(unsigned Index) { 86 assert(Index < (1u << 31) && "Index too large for virtual register range."); 87 return Index | MCRegister::VirtualRegFlag; 88 } 89 90 /// Return true if the specified register number is in the virtual register 91 /// namespace. 92 bool isVirtual() const { 93 return isVirtualRegister(Reg); 94 } 95 96 /// Return true if the specified register number is in the physical register 97 /// namespace. 98 bool isPhysical() const { 99 return isPhysicalRegister(Reg); 100 } 101 102 /// Convert a virtual register number to a 0-based index. The first virtual 103 /// register in a function will get the index 0. 104 unsigned virtRegIndex() const { 105 return virtReg2Index(Reg); 106 } 107 108 constexpr operator unsigned() const { 109 return Reg; 110 } 111 112 unsigned id() const { return Reg; } 113 114 operator MCRegister() const { 115 return MCRegister(Reg); 116 } 117 118 bool isValid() const { return Reg != MCRegister::NoRegister; } 119 120 /// Comparisons between register objects 121 bool operator==(const Register &Other) const { return Reg == Other.Reg; } 122 bool operator!=(const Register &Other) const { return Reg != Other.Reg; } 123 bool operator==(const MCRegister &Other) const { return Reg == Other.id(); } 124 bool operator!=(const MCRegister &Other) const { return Reg != Other.id(); } 125 126 /// Comparisons against register constants. E.g. 127 /// * R == AArch64::WZR 128 /// * R == 0 129 /// * R == VirtRegMap::NO_PHYS_REG 130 bool operator==(unsigned Other) const { return Reg == Other; } 131 bool operator!=(unsigned Other) const { return Reg != Other; } 132 bool operator==(int Other) const { return Reg == unsigned(Other); } 133 bool operator!=(int Other) const { return Reg != unsigned(Other); } 134 // MSVC requires that we explicitly declare these two as well. 135 bool operator==(MCPhysReg Other) const { return Reg == unsigned(Other); } 136 bool operator!=(MCPhysReg Other) const { return Reg != unsigned(Other); } 137 }; 138 139 // Provide DenseMapInfo for Register 140 template<> struct DenseMapInfo<Register> { 141 static inline unsigned getEmptyKey() { 142 return DenseMapInfo<unsigned>::getEmptyKey(); 143 } 144 static inline unsigned getTombstoneKey() { 145 return DenseMapInfo<unsigned>::getTombstoneKey(); 146 } 147 static unsigned getHashValue(const Register &Val) { 148 return DenseMapInfo<unsigned>::getHashValue(Val.id()); 149 } 150 static bool isEqual(const Register &LHS, const Register &RHS) { 151 return DenseMapInfo<unsigned>::isEqual(LHS.id(), RHS.id()); 152 } 153 }; 154 155 } 156 157 #endif // ifndef LLVM_CODEGEN_REGISTER_H 158