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 /// FIXME: remove in favor of member. 44 static bool isStackSlot(unsigned Reg) { 45 return MCRegister::isStackSlot(Reg); 46 } 47 48 /// Return true if this is a stack slot. 49 bool isStack() const { return MCRegister::isStackSlot(Reg); } 50 51 /// Compute the frame index from a register value representing a stack slot. 52 static int stackSlot2Index(Register Reg) { 53 assert(Reg.isStack() && "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 Register index2StackSlot(int FI) { 59 assert(FI >= 0 && "Cannot hold a negative frame index."); 60 return Register(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 return Reg & MCRegister::VirtualRegFlag; 73 } 74 75 /// Convert a virtual register number to a 0-based index. 76 /// The first virtual register in a function will get the index 0. 77 static unsigned virtReg2Index(Register Reg) { 78 assert(Reg.isVirtual() && "Not a virtual register"); 79 return Reg & ~MCRegister::VirtualRegFlag; 80 } 81 82 /// Convert a 0-based index to a virtual register number. 83 /// This is the inverse operation of VirtReg2IndexFunctor below. 84 static Register index2VirtReg(unsigned Index) { 85 assert(Index < (1u << 31) && "Index too large for virtual register range."); 86 return Index | MCRegister::VirtualRegFlag; 87 } 88 89 /// Return true if the specified register number is in the virtual register 90 /// namespace. 91 bool isVirtual() const { 92 return isVirtualRegister(Reg); 93 } 94 95 /// Return true if the specified register number is in the physical register 96 /// namespace. 97 bool isPhysical() const { 98 return isPhysicalRegister(Reg); 99 } 100 101 /// Convert a virtual register number to a 0-based index. The first virtual 102 /// register in a function will get the index 0. 103 unsigned virtRegIndex() const { 104 return virtReg2Index(Reg); 105 } 106 107 constexpr operator unsigned() const { 108 return Reg; 109 } 110 111 unsigned id() const { return Reg; } 112 113 operator MCRegister() const { 114 return MCRegister(Reg); 115 } 116 117 /// Utility to check-convert this value to a MCRegister. The caller is 118 /// expected to have already validated that this Register is, indeed, 119 /// physical. 120 MCRegister asMCReg() const { 121 assert(Reg == MCRegister::NoRegister || 122 MCRegister::isPhysicalRegister(Reg)); 123 return MCRegister(Reg); 124 } 125 126 bool isValid() const { return Reg != MCRegister::NoRegister; } 127 128 /// Comparisons between register objects 129 bool operator==(const Register &Other) const { return Reg == Other.Reg; } 130 bool operator!=(const Register &Other) const { return Reg != Other.Reg; } 131 bool operator==(const MCRegister &Other) const { return Reg == Other.id(); } 132 bool operator!=(const MCRegister &Other) const { return Reg != Other.id(); } 133 134 /// Comparisons against register constants. E.g. 135 /// * R == AArch64::WZR 136 /// * R == 0 137 /// * R == VirtRegMap::NO_PHYS_REG 138 bool operator==(unsigned Other) const { return Reg == Other; } 139 bool operator!=(unsigned Other) const { return Reg != Other; } 140 bool operator==(int Other) const { return Reg == unsigned(Other); } 141 bool operator!=(int Other) const { return Reg != unsigned(Other); } 142 // MSVC requires that we explicitly declare these two as well. 143 bool operator==(MCPhysReg Other) const { return Reg == unsigned(Other); } 144 bool operator!=(MCPhysReg Other) const { return Reg != unsigned(Other); } 145 }; 146 147 // Provide DenseMapInfo for Register 148 template<> struct DenseMapInfo<Register> { 149 static inline unsigned getEmptyKey() { 150 return DenseMapInfo<unsigned>::getEmptyKey(); 151 } 152 static inline unsigned getTombstoneKey() { 153 return DenseMapInfo<unsigned>::getTombstoneKey(); 154 } 155 static unsigned getHashValue(const Register &Val) { 156 return DenseMapInfo<unsigned>::getHashValue(Val.id()); 157 } 158 static bool isEqual(const Register &LHS, const Register &RHS) { 159 return DenseMapInfo<unsigned>::isEqual(LHS.id(), RHS.id()); 160 } 161 }; 162 163 } 164 165 #endif // LLVM_CODEGEN_REGISTER_H 166