1//===--- TypeLocBuilder.h - Type Source Info collector ----------*- 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 TypeLocBuilder, a class for building TypeLocs
10// bottom-up.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_LIB_SEMA_TYPELOCBUILDER_H
15#define LLVM_CLANG_LIB_SEMA_TYPELOCBUILDER_H
16
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/TypeLoc.h"
19
20namespace clang {
21
22class TypeLocBuilder {
23 static constexpr int InlineCapacity = 8 * sizeof(SourceLocation);
24
25 /// The underlying location-data buffer. Data grows from the end
26 /// of the buffer backwards.
27 char *Buffer;
28
29 /// The capacity of the current buffer.
30 size_t Capacity;
31
32 /// The index of the first occupied byte in the buffer.
33 size_t Index;
34
35#ifndef NDEBUG
36 /// The last type pushed on this builder.
37 QualType LastTy;
38#endif
39
40 /// The inline buffer.
41 static constexpr int BufferMaxAlignment = alignof(void *);
42 alignas(BufferMaxAlignment) char InlineBuffer[InlineCapacity];
43 unsigned NumBytesAtAlign4;
44 bool AtAlign8;
45
46public:
47 TypeLocBuilder()
48 : Buffer(InlineBuffer), Capacity(InlineCapacity), Index(InlineCapacity),
49 NumBytesAtAlign4(0), AtAlign8(false) {}
50
51 ~TypeLocBuilder() {
52 if (Buffer != InlineBuffer)
53 delete[] Buffer;
54 }
55
56 TypeLocBuilder(const TypeLocBuilder &) = delete;
57 TypeLocBuilder &operator=(const TypeLocBuilder &) = delete;
58
59 /// Ensures that this buffer has at least as much capacity as described.
60 void reserve(size_t Requested) {
61 if (Requested > Capacity)
62 // For now, match the request exactly.
63 grow(NewCapacity: Requested);
64 }
65
66 /// Pushes a copy of the given TypeLoc onto this builder. The builder
67 /// must be empty for this to work.
68 void pushFullCopy(TypeLoc L);
69
70 /// Pushes 'T' with all locations pointing to 'Loc'.
71 /// The builder must be empty for this to work.
72 void pushTrivial(ASTContext &Context, QualType T, SourceLocation Loc);
73
74 /// Pushes space for a typespec TypeLoc. Invalidates any TypeLocs
75 /// previously retrieved from this builder.
76 TypeSpecTypeLoc pushTypeSpec(QualType T) {
77 size_t LocalSize = TypeSpecTypeLoc::LocalDataSize;
78 unsigned LocalAlign = TypeSpecTypeLoc::LocalDataAlignment;
79 return pushImpl(T, LocalSize, LocalAlignment: LocalAlign).castAs<TypeSpecTypeLoc>();
80 }
81
82 /// Resets this builder to the newly-initialized state.
83 void clear() {
84#ifndef NDEBUG
85 LastTy = QualType();
86#endif
87 Index = Capacity;
88 NumBytesAtAlign4 = 0;
89 AtAlign8 = false;
90 }
91
92 /// Tell the TypeLocBuilder that the type it is storing has been
93 /// modified in some safe way that doesn't affect type-location information.
94 void TypeWasModifiedSafely(QualType T) {
95#ifndef NDEBUG
96 LastTy = T;
97#endif
98 }
99
100 /// Pushes space for a new TypeLoc of the given type. Invalidates
101 /// any TypeLocs previously retrieved from this builder.
102 template <class TyLocType> TyLocType push(QualType T) {
103 TyLocType Loc = TypeLoc(T, nullptr).castAs<TyLocType>();
104 size_t LocalSize = Loc.getLocalDataSize();
105 unsigned LocalAlign = Loc.getLocalDataAlignment();
106 return pushImpl(T, LocalSize, LocalAlignment: LocalAlign).castAs<TyLocType>();
107 }
108
109 /// Creates a TypeSourceInfo for the given type.
110 TypeSourceInfo *getTypeSourceInfo(ASTContext& Context, QualType T) {
111#ifndef NDEBUG
112 assert(T == LastTy && "type doesn't match last type pushed!");
113#endif
114
115 size_t FullDataSize = Capacity - Index;
116 TypeSourceInfo *DI = Context.CreateTypeSourceInfo(T, Size: FullDataSize);
117 memcpy(dest: DI->getTypeLoc().getOpaqueData(), src: &Buffer[Index], n: FullDataSize);
118 return DI;
119 }
120
121 /// Copies the type-location information to the given AST context and
122 /// returns a \c TypeLoc referring into the AST context.
123 TypeLoc getTypeLocInContext(ASTContext &Context, QualType T) {
124#ifndef NDEBUG
125 assert(T == LastTy && "type doesn't match last type pushed!");
126#endif
127
128 size_t FullDataSize = Capacity - Index;
129 void *Mem = Context.Allocate(Size: FullDataSize);
130 memcpy(dest: Mem, src: &Buffer[Index], n: FullDataSize);
131 return TypeLoc(T, Mem);
132 }
133
134private:
135
136 TypeLoc pushImpl(QualType T, size_t LocalSize, unsigned LocalAlignment);
137
138 /// Grow to the given capacity.
139 void grow(size_t NewCapacity);
140
141 /// Retrieve a temporary TypeLoc that refers into this \c TypeLocBuilder
142 /// object.
143 ///
144 /// The resulting \c TypeLoc should only be used so long as the
145 /// \c TypeLocBuilder is active and has not had more type information
146 /// pushed into it.
147 TypeLoc getTemporaryTypeLoc(QualType T) {
148#ifndef NDEBUG
149 assert(LastTy == T && "type doesn't match last type pushed!");
150#endif
151 return TypeLoc(T, &Buffer[Index]);
152 }
153};
154
155}
156
157#endif
158