1//===--- DeclAccessPair.h - A decl bundled with its path access -*- 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// This file defines the DeclAccessPair class, which provides an
10// efficient representation of a pair of a NamedDecl* and an
11// AccessSpecifier. Generally the access specifier gives the
12// natural access of a declaration when named in a class, as
13// defined in C++ [class.access.base]p1.
14//
15//===----------------------------------------------------------------------===//
16
17#ifndef LLVM_CLANG_AST_DECLACCESSPAIR_H
18#define LLVM_CLANG_AST_DECLACCESSPAIR_H
19
20#include "clang/Basic/Specifiers.h"
21#include "llvm/Support/DataTypes.h"
22#include "llvm/Support/Endian.h"
23
24namespace clang {
25
26class NamedDecl;
27
28/// A POD class for pairing a NamedDecl* with an access specifier.
29/// Can be put into unions.
30class DeclAccessPair {
31 /// Use the lower 2 bit to store AccessSpecifier. Use the higher
32 /// 61 bit to store the pointer to a NamedDecl or the DeclID to
33 /// a NamedDecl. If the 3rd bit is set, storing the DeclID, otherwise
34 /// storing the pointer.
35 llvm::support::detail::packed_endian_specific_integral<
36 uint64_t, llvm::endianness::native, alignof(void *)>
37 Ptr;
38
39 enum { ASMask = 0x3, Mask = 0x7 };
40
41 bool isDeclID() const { return (Ptr >> 2) & 0x1; }
42
43public:
44 static DeclAccessPair make(NamedDecl *D, AccessSpecifier AS) {
45 DeclAccessPair p;
46 p.set(D, AS);
47 return p;
48 }
49
50 static DeclAccessPair makeLazy(uint64_t ID, AccessSpecifier AS) {
51 DeclAccessPair p;
52 p.Ptr = (ID << 3) | (0x1 << 2) | uint64_t(AS);
53 return p;
54 }
55
56 uint64_t getDeclID() const {
57 assert(isDeclID());
58 return (~Mask & Ptr) >> 3;
59 }
60
61 NamedDecl *getDecl() const {
62 assert(!isDeclID());
63 return reinterpret_cast<NamedDecl*>(~Mask & Ptr);
64 }
65 AccessSpecifier getAccess() const { return AccessSpecifier(ASMask & Ptr); }
66
67 void setDecl(NamedDecl *D) {
68 set(D, AS: getAccess());
69 }
70 void setAccess(AccessSpecifier AS) {
71 set(D: getDecl(), AS);
72 }
73 void set(NamedDecl *D, AccessSpecifier AS) {
74 Ptr = uint64_t(AS) | reinterpret_cast<uint64_t>(D);
75 }
76
77 operator NamedDecl*() const { return getDecl(); }
78 NamedDecl *operator->() const { return getDecl(); }
79};
80
81// Make sure DeclAccessPair is pointer-aligned types.
82static_assert(alignof(DeclAccessPair) == alignof(void *));
83// Make sure DeclAccessPair is still POD.
84static_assert(std::is_standard_layout_v<DeclAccessPair> &&
85 std::is_trivial_v<DeclAccessPair>);
86}
87
88#endif
89