1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
#pragma once
#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter"
#endif
//===-- llvm/ADT/BitmaskEnum.h ----------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_BITMASKENUM_H
#define LLVM_ADT_BITMASKENUM_H
#include <cassert>
#include <type_traits>
#include <utility>
#include "llvm/Support/MathExtras.h"
/// LLVM_MARK_AS_BITMASK_ENUM lets you opt in an individual enum type so you can
/// perform bitwise operations on it without putting static_cast everywhere.
///
/// \code
/// enum MyEnum {
/// E1 = 1, E2 = 2, E3 = 4, E4 = 8,
/// LLVM_MARK_AS_BITMASK_ENUM(/* LargestValue = */ E4)
/// };
///
/// void Foo() {
/// MyEnum A = (E1 | E2) & E3 ^ ~E4; // Look, ma: No static_cast!
/// }
/// \endcode
///
/// Normally when you do a bitwise operation on an enum value, you get back an
/// instance of the underlying type (e.g. int). But using this macro, bitwise
/// ops on your enum will return you back instances of the enum. This is
/// particularly useful for enums which represent a combination of flags.
///
/// The parameter to LLVM_MARK_AS_BITMASK_ENUM should be the largest individual
/// value in your enum.
///
/// All of the enum's values must be non-negative.
#define LLVM_MARK_AS_BITMASK_ENUM(LargestValue) \
LLVM_BITMASK_LARGEST_ENUMERATOR = LargestValue
/// LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE() pulls the operator overloads used
/// by LLVM_MARK_AS_BITMASK_ENUM into the current namespace.
///
/// Suppose you have an enum foo::bar::MyEnum. Before using
/// LLVM_MARK_AS_BITMASK_ENUM on MyEnum, you must put
/// LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE() somewhere inside namespace foo or
/// namespace foo::bar. This allows the relevant operator overloads to be found
/// by ADL.
///
/// You don't need to use this macro in namespace llvm; it's done at the bottom
/// of this file.
#define LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE() \
using ::llvm::BitmaskEnumDetail::operator~; \
using ::llvm::BitmaskEnumDetail::operator|; \
using ::llvm::BitmaskEnumDetail::operator&; \
using ::llvm::BitmaskEnumDetail::operator^; \
using ::llvm::BitmaskEnumDetail::operator|=; \
using ::llvm::BitmaskEnumDetail::operator&=; \
/* Force a semicolon at the end of this macro. */ \
using ::llvm::BitmaskEnumDetail::operator^=
namespace llvm {
/// Traits class to determine whether an enum has a
/// LLVM_BITMASK_LARGEST_ENUMERATOR enumerator.
template <typename E, typename Enable = void>
struct is_bitmask_enum : std::false_type {};
template <typename E>
struct is_bitmask_enum<
E, std::enable_if_t<sizeof(E::LLVM_BITMASK_LARGEST_ENUMERATOR) >= 0>>
: std::true_type {};
namespace BitmaskEnumDetail {
/// Get a bitmask with 1s in all places up to the high-order bit of E's largest
/// value.
template <typename E> std::underlying_type_t<E> Mask() {
// On overflow, NextPowerOf2 returns zero with the type uint64_t, so
// subtracting 1 gives us the mask with all bits set, like we want.
return NextPowerOf2(static_cast<std::underlying_type_t<E>>(
E::LLVM_BITMASK_LARGEST_ENUMERATOR)) -
1;
}
/// Check that Val is in range for E, and return Val cast to E's underlying
/// type.
template <typename E> std::underlying_type_t<E> Underlying(E Val) {
auto U = static_cast<std::underlying_type_t<E>>(Val);
assert(U >= 0 && "Negative enum values are not allowed.");
assert(U <= Mask<E>() && "Enum value too large (or largest val too small?)");
return U;
}
constexpr unsigned bitWidth(uint64_t Value) {
return Value ? 1 + bitWidth(Value >> 1) : 0;
}
template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
E operator~(E Val) {
return static_cast<E>(~Underlying(Val) & Mask<E>());
}
template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
E operator|(E LHS, E RHS) {
return static_cast<E>(Underlying(LHS) | Underlying(RHS));
}
template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
E operator&(E LHS, E RHS) {
return static_cast<E>(Underlying(LHS) & Underlying(RHS));
}
template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
E operator^(E LHS, E RHS) {
return static_cast<E>(Underlying(LHS) ^ Underlying(RHS));
}
// |=, &=, and ^= return a reference to LHS, to match the behavior of the
// operators on builtin types.
template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
E &operator|=(E &LHS, E RHS) {
LHS = LHS | RHS;
return LHS;
}
template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
E &operator&=(E &LHS, E RHS) {
LHS = LHS & RHS;
return LHS;
}
template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
E &operator^=(E &LHS, E RHS) {
LHS = LHS ^ RHS;
return LHS;
}
} // namespace BitmaskEnumDetail
// Enable bitmask enums in namespace ::llvm and all nested namespaces.
LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();
template <typename E, typename = std::enable_if_t<is_bitmask_enum<E>::value>>
constexpr unsigned BitWidth = BitmaskEnumDetail::bitWidth(uint64_t{
static_cast<std::underlying_type_t<E>>(
E::LLVM_BITMASK_LARGEST_ENUMERATOR)});
} // namespace llvm
#endif
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif
|
