1//===-- llvm/MC/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_MC_REGISTER_H
10#define LLVM_MC_REGISTER_H
11
12#include "llvm/ADT/DenseMapInfo.h"
13#include <cassert>
14
15namespace llvm {
16
17/// An unsigned integer type large enough to represent all physical registers,
18/// but not necessarily virtual registers.
19using MCPhysReg = uint16_t;
20
21/// Wrapper class representing physical registers. Should be passed by value.
22class MCRegister {
23  unsigned Reg;
24
25public:
26  MCRegister(unsigned Val = 0): Reg(Val) {}
27
28  // Register numbers can represent physical registers, virtual registers, and
29  // sometimes stack slots. The unsigned values are divided into these ranges:
30  //
31  //   0           Not a register, can be used as a sentinel.
32  //   [1;2^30)    Physical registers assigned by TableGen.
33  //   [2^30;2^31) Stack slots. (Rarely used.)
34  //   [2^31;2^32) Virtual registers assigned by MachineRegisterInfo.
35  //
36  // Further sentinels can be allocated from the small negative integers.
37  // DenseMapInfo<unsigned> uses -1u and -2u.
38
39  /// This is the portion of the positive number space that is not a physical
40  /// register. StackSlot values do not exist in the MC layer, see
41  /// Register::isStackSlot() for the more information on them.
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  static bool isStackSlot(unsigned Reg) {
47    return int(Reg) >= (1 << 30);
48  }
49
50  /// Return true if the specified register number is in
51  /// the physical register namespace.
52  static bool isPhysicalRegister(unsigned Reg) {
53    assert(!isStackSlot(Reg) && "Not a register! Check isStackSlot() first.");
54    return int(Reg) > 0;
55  }
56
57  /// Return true if the specified register number is in the physical register
58  /// namespace.
59  bool isPhysical() const {
60    return isPhysicalRegister(Reg);
61  }
62
63  operator unsigned() const {
64    return Reg;
65  }
66
67  unsigned id() const {
68    return Reg;
69  }
70
71  bool isValid() const {
72    return Reg != 0;
73  }
74
75  /// Comparisons between register objects
76  bool operator==(const MCRegister &Other) const { return Reg == Other.Reg; }
77  bool operator!=(const MCRegister &Other) const { return Reg != Other.Reg; }
78
79  /// Comparisons against register constants. E.g.
80  /// * R == AArch64::WZR
81  /// * R == 0
82  /// * R == VirtRegMap::NO_PHYS_REG
83  bool operator==(unsigned Other) const { return Reg == Other; }
84  bool operator!=(unsigned Other) const { return Reg != Other; }
85  bool operator==(int Other) const { return Reg == unsigned(Other); }
86  bool operator!=(int Other) const { return Reg != unsigned(Other); }
87  // MSVC requires that we explicitly declare these two as well.
88  bool operator==(MCPhysReg Other) const { return Reg == unsigned(Other); }
89  bool operator!=(MCPhysReg Other) const { return Reg != unsigned(Other); }
90};
91
92// Provide DenseMapInfo for MCRegister
93template<> struct DenseMapInfo<MCRegister> {
94  static inline unsigned getEmptyKey() {
95    return DenseMapInfo<unsigned>::getEmptyKey();
96  }
97  static inline unsigned getTombstoneKey() {
98    return DenseMapInfo<unsigned>::getTombstoneKey();
99  }
100  static unsigned getHashValue(const MCRegister &Val) {
101    return DenseMapInfo<unsigned>::getHashValue(Val.id());
102  }
103  static bool isEqual(const MCRegister &LHS, const MCRegister &RHS) {
104    return DenseMapInfo<unsigned>::isEqual(LHS.id(), RHS.id());
105  }
106};
107
108}
109
110#endif // ifndef LLVM_MC_REGISTER_H
111