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
15namespace llvm {
16
17/// Wrapper class representing virtual and physical registers. Should be passed
18/// by value.
19class Register {
20  unsigned Reg;
21
22public:
23  Register(unsigned Val = 0): Reg(Val) {}
24  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
37  /// isStackSlot - Sometimes it is useful the be able to store a non-negative
38  /// frame index in a variable that normally holds a register. isStackSlot()
39  /// returns true if Reg is in the range used for stack slots.
40  ///
41  /// Note that isVirtualRegister() and isPhysicalRegister() cannot handle stack
42  /// slots, so if a variable may contains a stack slot, always check
43  /// isStackSlot() first.
44  ///
45  static bool isStackSlot(unsigned Reg) {
46    return MCRegister::isStackSlot(Reg);
47  }
48
49  /// Compute the frame index from a register value representing a stack slot.
50  static int stackSlot2Index(unsigned Reg) {
51    assert(isStackSlot(Reg) && "Not a stack slot");
52    return int(Reg - (1u << 30));
53  }
54
55  /// Convert a non-negative frame index to a stack slot register value.
56  static unsigned index2StackSlot(int FI) {
57    assert(FI >= 0 && "Cannot hold a negative frame index.");
58    return FI + (1u << 30);
59  }
60
61  /// Return true if the specified register number is in
62  /// the physical register namespace.
63  static bool isPhysicalRegister(unsigned Reg) {
64    return MCRegister::isPhysicalRegister(Reg);
65  }
66
67  /// Return true if the specified register number is in
68  /// the virtual register namespace.
69  static bool isVirtualRegister(unsigned Reg) {
70    assert(!isStackSlot(Reg) && "Not a register! Check isStackSlot() first.");
71    return int(Reg) < 0;
72  }
73
74  /// Convert a virtual register number to a 0-based index.
75  /// The first virtual register in a function will get the index 0.
76  static unsigned virtReg2Index(unsigned Reg) {
77    assert(isVirtualRegister(Reg) && "Not a virtual register");
78    return Reg & ~(1u << 31);
79  }
80
81  /// Convert a 0-based index to a virtual register number.
82  /// This is the inverse operation of VirtReg2IndexFunctor below.
83  static unsigned index2VirtReg(unsigned Index) {
84    return Index | (1u << 31);
85  }
86
87  /// Return true if the specified register number is in the virtual register
88  /// namespace.
89  bool isVirtual() const {
90    return isVirtualRegister(Reg);
91  }
92
93  /// Return true if the specified register number is in the physical register
94  /// namespace.
95  bool isPhysical() const {
96    return isPhysicalRegister(Reg);
97  }
98
99  /// Convert a virtual register number to a 0-based index. The first virtual
100  /// register in a function will get the index 0.
101  unsigned virtRegIndex() const {
102    return virtReg2Index(Reg);
103  }
104
105  operator unsigned() const {
106    return Reg;
107  }
108
109  unsigned id() const { return Reg; }
110
111  operator MCRegister() const {
112    return MCRegister(Reg);
113  }
114
115  bool isValid() const {
116    return Reg != 0;
117  }
118
119  /// Comparisons between register objects
120  bool operator==(const Register &Other) const { return Reg == Other.Reg; }
121  bool operator!=(const Register &Other) const { return Reg != Other.Reg; }
122  bool operator==(const MCRegister &Other) const { return Reg == Other.id(); }
123  bool operator!=(const MCRegister &Other) const { return Reg != Other.id(); }
124
125  /// Comparisons against register constants. E.g.
126  /// * R == AArch64::WZR
127  /// * R == 0
128  /// * R == VirtRegMap::NO_PHYS_REG
129  bool operator==(unsigned Other) const { return Reg == Other; }
130  bool operator!=(unsigned Other) const { return Reg != Other; }
131  bool operator==(int Other) const { return Reg == unsigned(Other); }
132  bool operator!=(int Other) const { return Reg != unsigned(Other); }
133  // MSVC requires that we explicitly declare these two as well.
134  bool operator==(MCPhysReg Other) const { return Reg == unsigned(Other); }
135  bool operator!=(MCPhysReg Other) const { return Reg != unsigned(Other); }
136};
137
138// Provide DenseMapInfo for Register
139template<> struct DenseMapInfo<Register> {
140  static inline unsigned getEmptyKey() {
141    return DenseMapInfo<unsigned>::getEmptyKey();
142  }
143  static inline unsigned getTombstoneKey() {
144    return DenseMapInfo<unsigned>::getTombstoneKey();
145  }
146  static unsigned getHashValue(const Register &Val) {
147    return DenseMapInfo<unsigned>::getHashValue(Val.id());
148  }
149  static bool isEqual(const Register &LHS, const Register &RHS) {
150    return DenseMapInfo<unsigned>::isEqual(LHS.id(), RHS.id());
151  }
152};
153
154}
155
156#endif // ifndef LLVM_CODEGEN_REGISTER_H
157