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: Reg(Val)23 constexpr Register(unsigned Val = 0) : Reg(Val) {} Register(MCRegister 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 to 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. isStackSlot(unsigned Reg)44 static constexpr bool isStackSlot(unsigned Reg) { 45 return MCRegister::isStackSlot(Reg); 46 } 47 48 /// Return true if this is a stack slot. isStack()49 constexpr bool isStack() const { return MCRegister::isStackSlot(Reg); } 50 51 /// Compute the frame index from a register value representing a stack slot. stackSlot2Index(Register Reg)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. index2StackSlot(int FI)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. isPhysicalRegister(unsigned Reg)65 static constexpr 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. isVirtualRegister(unsigned Reg)71 static constexpr 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. virtReg2Index(Register Reg)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. index2VirtReg(unsigned Index)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. isVirtual()91 constexpr bool isVirtual() const { return isVirtualRegister(Reg); } 92 93 /// Return true if the specified register number is in the physical register 94 /// namespace. isPhysical()95 constexpr bool isPhysical() const { return isPhysicalRegister(Reg); } 96 97 /// Convert a virtual register number to a 0-based index. The first virtual 98 /// register in a function will get the index 0. virtRegIndex()99 unsigned virtRegIndex() const { return virtReg2Index(Reg); } 100 101 constexpr operator unsigned() const { return Reg; } 102 id()103 constexpr unsigned id() const { return Reg; } 104 MCRegister()105 constexpr operator MCRegister() const { return MCRegister(Reg); } 106 107 /// Utility to check-convert this value to a MCRegister. The caller is 108 /// expected to have already validated that this Register is, indeed, 109 /// physical. asMCReg()110 MCRegister asMCReg() const { 111 assert(Reg == MCRegister::NoRegister || 112 MCRegister::isPhysicalRegister(Reg)); 113 return MCRegister(Reg); 114 } 115 isValid()116 constexpr bool isValid() const { return Reg != MCRegister::NoRegister; } 117 118 /// Comparisons between register objects 119 constexpr bool operator==(const Register &Other) const { 120 return Reg == Other.Reg; 121 } 122 constexpr bool operator!=(const Register &Other) const { 123 return Reg != Other.Reg; 124 } 125 constexpr bool operator==(const MCRegister &Other) const { 126 return Reg == Other.id(); 127 } 128 constexpr bool operator!=(const MCRegister &Other) const { 129 return Reg != Other.id(); 130 } 131 132 /// Comparisons against register constants. E.g. 133 /// * R == AArch64::WZR 134 /// * R == 0 135 /// * R == VirtRegMap::NO_PHYS_REG 136 constexpr bool operator==(unsigned Other) const { return Reg == Other; } 137 constexpr bool operator!=(unsigned Other) const { return Reg != Other; } 138 constexpr bool operator==(int Other) const { return Reg == unsigned(Other); } 139 constexpr bool operator!=(int Other) const { return Reg != unsigned(Other); } 140 // MSVC requires that we explicitly declare these two as well. 141 constexpr bool operator==(MCPhysReg Other) const { 142 return Reg == unsigned(Other); 143 } 144 constexpr bool operator!=(MCPhysReg Other) const { 145 return Reg != unsigned(Other); 146 } 147 }; 148 149 // Provide DenseMapInfo for Register 150 template <> struct DenseMapInfo<Register> { 151 static inline unsigned getEmptyKey() { 152 return DenseMapInfo<unsigned>::getEmptyKey(); 153 } 154 static inline unsigned getTombstoneKey() { 155 return DenseMapInfo<unsigned>::getTombstoneKey(); 156 } 157 static unsigned getHashValue(const Register &Val) { 158 return DenseMapInfo<unsigned>::getHashValue(Val.id()); 159 } 160 static bool isEqual(const Register &LHS, const Register &RHS) { 161 return DenseMapInfo<unsigned>::isEqual(LHS.id(), RHS.id()); 162 } 163 }; 164 165 } // namespace llvm 166 167 #endif // LLVM_CODEGEN_REGISTER_H 168