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 20 namespace clang { 21 22 class TypeLocBuilder { 23 enum { 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 enum { BufferMaxAlignment = alignof(void *) }; 42 alignas(BufferMaxAlignment) char InlineBuffer[InlineCapacity]; 43 unsigned NumBytesAtAlign4, NumBytesAtAlign8; 44 45 public: 46 TypeLocBuilder() 47 : Buffer(InlineBuffer), Capacity(InlineCapacity), Index(InlineCapacity), 48 NumBytesAtAlign4(0), NumBytesAtAlign8(0) {} 49 50 ~TypeLocBuilder() { 51 if (Buffer != InlineBuffer) 52 delete[] Buffer; 53 } 54 55 /// Ensures that this buffer has at least as much capacity as described. 56 void reserve(size_t Requested) { 57 if (Requested > Capacity) 58 // For now, match the request exactly. 59 grow(Requested); 60 } 61 62 /// Pushes a copy of the given TypeLoc onto this builder. The builder 63 /// must be empty for this to work. 64 void pushFullCopy(TypeLoc L); 65 66 /// Pushes space for a typespec TypeLoc. Invalidates any TypeLocs 67 /// previously retrieved from this builder. 68 TypeSpecTypeLoc pushTypeSpec(QualType T) { 69 size_t LocalSize = TypeSpecTypeLoc::LocalDataSize; 70 unsigned LocalAlign = TypeSpecTypeLoc::LocalDataAlignment; 71 return pushImpl(T, LocalSize, LocalAlign).castAs<TypeSpecTypeLoc>(); 72 } 73 74 /// Resets this builder to the newly-initialized state. 75 void clear() { 76 #ifndef NDEBUG 77 LastTy = QualType(); 78 #endif 79 Index = Capacity; 80 NumBytesAtAlign4 = NumBytesAtAlign8 = 0; 81 } 82 83 /// Tell the TypeLocBuilder that the type it is storing has been 84 /// modified in some safe way that doesn't affect type-location information. 85 void TypeWasModifiedSafely(QualType T) { 86 #ifndef NDEBUG 87 LastTy = T; 88 #endif 89 } 90 91 /// Pushes space for a new TypeLoc of the given type. Invalidates 92 /// any TypeLocs previously retrieved from this builder. 93 template <class TyLocType> TyLocType push(QualType T) { 94 TyLocType Loc = TypeLoc(T, nullptr).castAs<TyLocType>(); 95 size_t LocalSize = Loc.getLocalDataSize(); 96 unsigned LocalAlign = Loc.getLocalDataAlignment(); 97 return pushImpl(T, LocalSize, LocalAlign).castAs<TyLocType>(); 98 } 99 100 /// Creates a TypeSourceInfo for the given type. 101 TypeSourceInfo *getTypeSourceInfo(ASTContext& Context, QualType T) { 102 #ifndef NDEBUG 103 assert(T == LastTy && "type doesn't match last type pushed!"); 104 #endif 105 106 size_t FullDataSize = Capacity - Index; 107 TypeSourceInfo *DI = Context.CreateTypeSourceInfo(T, FullDataSize); 108 memcpy(DI->getTypeLoc().getOpaqueData(), &Buffer[Index], FullDataSize); 109 return DI; 110 } 111 112 /// Copies the type-location information to the given AST context and 113 /// returns a \c TypeLoc referring into the AST context. 114 TypeLoc getTypeLocInContext(ASTContext &Context, QualType T) { 115 #ifndef NDEBUG 116 assert(T == LastTy && "type doesn't match last type pushed!"); 117 #endif 118 119 size_t FullDataSize = Capacity - Index; 120 void *Mem = Context.Allocate(FullDataSize); 121 memcpy(Mem, &Buffer[Index], FullDataSize); 122 return TypeLoc(T, Mem); 123 } 124 125 private: 126 127 TypeLoc pushImpl(QualType T, size_t LocalSize, unsigned LocalAlignment); 128 129 /// Grow to the given capacity. 130 void grow(size_t NewCapacity); 131 132 /// Retrieve a temporary TypeLoc that refers into this \c TypeLocBuilder 133 /// object. 134 /// 135 /// The resulting \c TypeLoc should only be used so long as the 136 /// \c TypeLocBuilder is active and has not had more type information 137 /// pushed into it. 138 TypeLoc getTemporaryTypeLoc(QualType T) { 139 #ifndef NDEBUG 140 assert(LastTy == T && "type doesn't match last type pushed!"); 141 #endif 142 return TypeLoc(T, &Buffer[Index]); 143 } 144 }; 145 146 } 147 148 #endif 149