1 | //===- Ownership.h - Parser ownership helpers -------------------*- 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 contains classes for managing ownership of Stmt and Expr nodes. |
10 | // |
11 | //===----------------------------------------------------------------------===// |
12 | |
13 | #ifndef LLVM_CLANG_SEMA_OWNERSHIP_H |
14 | #define LLVM_CLANG_SEMA_OWNERSHIP_H |
15 | |
16 | #include "clang/AST/Expr.h" |
17 | #include "clang/Basic/LLVM.h" |
18 | #include "llvm/ADT/ArrayRef.h" |
19 | #include "llvm/Support/PointerLikeTypeTraits.h" |
20 | #include "llvm/Support/type_traits.h" |
21 | #include <cassert> |
22 | #include <cstddef> |
23 | #include <cstdint> |
24 | |
25 | //===----------------------------------------------------------------------===// |
26 | // OpaquePtr |
27 | //===----------------------------------------------------------------------===// |
28 | |
29 | namespace clang { |
30 | |
31 | class CXXBaseSpecifier; |
32 | class CXXCtorInitializer; |
33 | class Decl; |
34 | class Expr; |
35 | class ParsedTemplateArgument; |
36 | class QualType; |
37 | class Stmt; |
38 | class TemplateName; |
39 | class TemplateParameterList; |
40 | |
41 | /// Wrapper for void* pointer. |
42 | /// \tparam PtrTy Either a pointer type like 'T*' or a type that behaves like |
43 | /// a pointer. |
44 | /// |
45 | /// This is a very simple POD type that wraps a pointer that the Parser |
46 | /// doesn't know about but that Sema or another client does. The PtrTy |
47 | /// template argument is used to make sure that "Decl" pointers are not |
48 | /// compatible with "Type" pointers for example. |
49 | template <class PtrTy> |
50 | class OpaquePtr { |
51 | void *Ptr = nullptr; |
52 | |
53 | explicit OpaquePtr(void *Ptr) : Ptr(Ptr) {} |
54 | |
55 | using Traits = llvm::PointerLikeTypeTraits<PtrTy>; |
56 | |
57 | public: |
58 | OpaquePtr(std::nullptr_t = nullptr) {} |
59 | |
60 | static OpaquePtr make(PtrTy P) { OpaquePtr OP; OP.set(P); return OP; } |
61 | |
62 | /// Returns plain pointer to the entity pointed by this wrapper. |
63 | /// \tparam PointeeT Type of pointed entity. |
64 | /// |
65 | /// It is identical to getPtrAs<PointeeT*>. |
66 | template <typename PointeeT> PointeeT* getPtrTo() const { |
67 | return get(); |
68 | } |
69 | |
70 | /// Returns pointer converted to the specified type. |
71 | /// \tparam PtrT Result pointer type. There must be implicit conversion |
72 | /// from PtrTy to PtrT. |
73 | /// |
74 | /// In contrast to getPtrTo, this method allows the return type to be |
75 | /// a smart pointer. |
76 | template <typename PtrT> PtrT getPtrAs() const { |
77 | return get(); |
78 | } |
79 | |
80 | PtrTy get() const { |
81 | return Traits::getFromVoidPointer(Ptr); |
82 | } |
83 | |
84 | void set(PtrTy P) { |
85 | Ptr = Traits::getAsVoidPointer(P); |
86 | } |
87 | |
88 | explicit operator bool() const { return Ptr != nullptr; } |
89 | |
90 | void *getAsOpaquePtr() const { return Ptr; } |
91 | static OpaquePtr getFromOpaquePtr(void *P) { return OpaquePtr(P); } |
92 | }; |
93 | |
94 | /// UnionOpaquePtr - A version of OpaquePtr suitable for membership |
95 | /// in a union. |
96 | template <class T> struct UnionOpaquePtr { |
97 | void *Ptr; |
98 | |
99 | static UnionOpaquePtr make(OpaquePtr<T> P) { |
100 | UnionOpaquePtr OP = { P.getAsOpaquePtr() }; |
101 | return OP; |
102 | } |
103 | |
104 | OpaquePtr<T> get() const { return OpaquePtr<T>::getFromOpaquePtr(Ptr); } |
105 | operator OpaquePtr<T>() const { return get(); } |
106 | |
107 | UnionOpaquePtr &operator=(OpaquePtr<T> P) { |
108 | Ptr = P.getAsOpaquePtr(); |
109 | return *this; |
110 | } |
111 | }; |
112 | |
113 | } // namespace clang |
114 | |
115 | namespace llvm { |
116 | |
117 | template <class T> |
118 | struct PointerLikeTypeTraits<clang::OpaquePtr<T>> { |
119 | static constexpr int NumLowBitsAvailable = 0; |
120 | |
121 | static inline void *getAsVoidPointer(clang::OpaquePtr<T> P) { |
122 | // FIXME: Doesn't work? return P.getAs< void >(); |
123 | return P.getAsOpaquePtr(); |
124 | } |
125 | |
126 | static inline clang::OpaquePtr<T> getFromVoidPointer(void *P) { |
127 | return clang::OpaquePtr<T>::getFromOpaquePtr(P); |
128 | } |
129 | }; |
130 | |
131 | } // namespace llvm |
132 | |
133 | namespace clang { |
134 | |
135 | // Basic |
136 | class StreamingDiagnostic; |
137 | |
138 | // Determines whether the low bit of the result pointer for the |
139 | // given UID is always zero. If so, ActionResult will use that bit |
140 | // for it's "invalid" flag. |
141 | template <class Ptr> struct IsResultPtrLowBitFree { |
142 | static const bool value = false; |
143 | }; |
144 | |
145 | /// ActionResult - This structure is used while parsing/acting on |
146 | /// expressions, stmts, etc. It encapsulates both the object returned by |
147 | /// the action, plus a sense of whether or not it is valid. |
148 | /// When CompressInvalid is true, the "invalid" flag will be |
149 | /// stored in the low bit of the Val pointer. |
150 | template<class PtrTy, |
151 | bool CompressInvalid = IsResultPtrLowBitFree<PtrTy>::value> |
152 | class ActionResult { |
153 | PtrTy Val; |
154 | bool Invalid; |
155 | |
156 | public: |
157 | ActionResult(bool Invalid = false) : Val(PtrTy()), Invalid(Invalid) {} |
158 | ActionResult(PtrTy val) : Val(val), Invalid(false) {} |
159 | ActionResult(const DiagnosticBuilder &) : Val(PtrTy()), Invalid(true) {} |
160 | |
161 | // These two overloads prevent void* -> bool conversions. |
162 | ActionResult(const void *) = delete; |
163 | ActionResult(volatile void *) = delete; |
164 | |
165 | bool isInvalid() const { return Invalid; } |
166 | bool isUsable() const { return !Invalid && Val; } |
167 | bool isUnset() const { return !Invalid && !Val; } |
168 | |
169 | PtrTy get() const { return Val; } |
170 | template <typename T> T *getAs() { return static_cast<T*>(get()); } |
171 | |
172 | void set(PtrTy V) { Val = V; } |
173 | |
174 | const ActionResult &operator=(PtrTy RHS) { |
175 | Val = RHS; |
176 | Invalid = false; |
177 | return *this; |
178 | } |
179 | }; |
180 | |
181 | // This ActionResult partial specialization places the "invalid" |
182 | // flag into the low bit of the pointer. |
183 | template<typename PtrTy> |
184 | class ActionResult<PtrTy, true> { |
185 | // A pointer whose low bit is 1 if this result is invalid, 0 |
186 | // otherwise. |
187 | uintptr_t PtrWithInvalid; |
188 | |
189 | using PtrTraits = llvm::PointerLikeTypeTraits<PtrTy>; |
190 | |
191 | public: |
192 | ActionResult(bool Invalid = false) |
193 | : PtrWithInvalid(static_cast<uintptr_t>(Invalid)) {} |
194 | |
195 | ActionResult(PtrTy V) { |
196 | void *VP = PtrTraits::getAsVoidPointer(V); |
197 | PtrWithInvalid = reinterpret_cast<uintptr_t>(VP); |
198 | assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer" ); |
199 | } |
200 | |
201 | ActionResult(const DiagnosticBuilder &) : PtrWithInvalid(0x01) {} |
202 | |
203 | // These two overloads prevent void* -> bool conversions. |
204 | ActionResult(const void *) = delete; |
205 | ActionResult(volatile void *) = delete; |
206 | |
207 | bool isInvalid() const { return PtrWithInvalid & 0x01; } |
208 | bool isUsable() const { return PtrWithInvalid > 0x01; } |
209 | bool isUnset() const { return PtrWithInvalid == 0; } |
210 | |
211 | PtrTy get() const { |
212 | void *VP = reinterpret_cast<void *>(PtrWithInvalid & ~0x01); |
213 | return PtrTraits::getFromVoidPointer(VP); |
214 | } |
215 | |
216 | template <typename T> T *getAs() { return static_cast<T*>(get()); } |
217 | |
218 | void set(PtrTy V) { |
219 | void *VP = PtrTraits::getAsVoidPointer(V); |
220 | PtrWithInvalid = reinterpret_cast<uintptr_t>(VP); |
221 | assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer" ); |
222 | } |
223 | |
224 | const ActionResult &operator=(PtrTy RHS) { |
225 | void *VP = PtrTraits::getAsVoidPointer(RHS); |
226 | PtrWithInvalid = reinterpret_cast<uintptr_t>(VP); |
227 | assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer" ); |
228 | return *this; |
229 | } |
230 | |
231 | // For types where we can fit a flag in with the pointer, provide |
232 | // conversions to/from pointer type. |
233 | static ActionResult getFromOpaquePointer(void *P) { |
234 | ActionResult Result; |
235 | Result.PtrWithInvalid = (uintptr_t)P; |
236 | return Result; |
237 | } |
238 | void *getAsOpaquePointer() const { return (void*)PtrWithInvalid; } |
239 | }; |
240 | |
241 | /// An opaque type for threading parsed type information through the |
242 | /// parser. |
243 | using ParsedType = OpaquePtr<QualType>; |
244 | using UnionParsedType = UnionOpaquePtr<QualType>; |
245 | |
246 | // We can re-use the low bit of expression, statement, base, and |
247 | // member-initializer pointers for the "invalid" flag of |
248 | // ActionResult. |
249 | template<> struct IsResultPtrLowBitFree<Expr*> { |
250 | static const bool value = true; |
251 | }; |
252 | template<> struct IsResultPtrLowBitFree<Stmt*> { |
253 | static const bool value = true; |
254 | }; |
255 | template<> struct IsResultPtrLowBitFree<CXXBaseSpecifier*> { |
256 | static const bool value = true; |
257 | }; |
258 | template<> struct IsResultPtrLowBitFree<CXXCtorInitializer*> { |
259 | static const bool value = true; |
260 | }; |
261 | |
262 | using ExprResult = ActionResult<Expr *>; |
263 | using StmtResult = ActionResult<Stmt *>; |
264 | using TypeResult = ActionResult<ParsedType>; |
265 | using BaseResult = ActionResult<CXXBaseSpecifier *>; |
266 | using MemInitResult = ActionResult<CXXCtorInitializer *>; |
267 | |
268 | using DeclResult = ActionResult<Decl *>; |
269 | using ParsedTemplateTy = OpaquePtr<TemplateName>; |
270 | using UnionParsedTemplateTy = UnionOpaquePtr<TemplateName>; |
271 | |
272 | using MultiExprArg = MutableArrayRef<Expr *>; |
273 | using MultiStmtArg = MutableArrayRef<Stmt *>; |
274 | using ASTTemplateArgsPtr = MutableArrayRef<ParsedTemplateArgument>; |
275 | using MultiTypeArg = MutableArrayRef<ParsedType>; |
276 | using MultiTemplateParamsArg = MutableArrayRef<TemplateParameterList *>; |
277 | |
278 | inline ExprResult ExprError() { return ExprResult(true); } |
279 | inline StmtResult StmtError() { return StmtResult(true); } |
280 | inline TypeResult TypeError() { return TypeResult(true); } |
281 | |
282 | inline ExprResult ExprError(const StreamingDiagnostic &) { |
283 | return ExprError(); |
284 | } |
285 | inline StmtResult StmtError(const StreamingDiagnostic &) { |
286 | return StmtError(); |
287 | } |
288 | |
289 | inline ExprResult ExprEmpty() { return ExprResult(false); } |
290 | inline StmtResult StmtEmpty() { return StmtResult(false); } |
291 | |
292 | inline Expr *AssertSuccess(ExprResult R) { |
293 | assert(!R.isInvalid() && "operation was asserted to never fail!" ); |
294 | return R.get(); |
295 | } |
296 | |
297 | inline Stmt *AssertSuccess(StmtResult R) { |
298 | assert(!R.isInvalid() && "operation was asserted to never fail!" ); |
299 | return R.get(); |
300 | } |
301 | |
302 | } // namespace clang |
303 | |
304 | #endif // LLVM_CLANG_SEMA_OWNERSHIP_H |
305 | |