1//===----- CGObjCRuntime.h - Interface to ObjC Runtimes ---------*- 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 provides an abstract class for Objective-C code generation. Concrete
10// subclasses of this implement code generation for specific Objective-C
11// runtime libraries.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_CLANG_LIB_CODEGEN_CGOBJCRUNTIME_H
16#define LLVM_CLANG_LIB_CODEGEN_CGOBJCRUNTIME_H
17#include "CGBuilder.h"
18#include "CGCall.h"
19#include "CGCleanup.h"
20#include "CGValue.h"
21#include "clang/AST/DeclObjC.h"
22#include "clang/Basic/IdentifierTable.h" // Selector
23#include "llvm/ADT/UniqueVector.h"
24
25namespace llvm {
26class Constant;
27class Function;
28class Module;
29class StructLayout;
30class StructType;
31class Type;
32class Value;
33} // namespace llvm
34
35namespace clang {
36namespace CodeGen {
37class CGFunctionInfo;
38class CodeGenFunction;
39} // namespace CodeGen
40
41class FieldDecl;
42class ObjCAtTryStmt;
43class ObjCAtThrowStmt;
44class ObjCAtSynchronizedStmt;
45class ObjCContainerDecl;
46class ObjCCategoryImplDecl;
47class ObjCImplementationDecl;
48class ObjCInterfaceDecl;
49class ObjCMessageExpr;
50class ObjCMethodDecl;
51class ObjCProtocolDecl;
52class Selector;
53class ObjCIvarDecl;
54class ObjCStringLiteral;
55class BlockDeclRefExpr;
56
57namespace CodeGen {
58class CodeGenModule;
59class CGBlockInfo;
60
61// FIXME: Several methods should be pure virtual but aren't to avoid the
62// partially-implemented subclass breaking.
63
64/// Implements runtime-specific code generation functions.
65class CGObjCRuntime {
66protected:
67 CodeGen::CodeGenModule &CGM;
68 CGObjCRuntime(CodeGen::CodeGenModule &CGM) : CGM(CGM) {}
69
70 // Utility functions for unified ivar access. These need to
71 // eventually be folded into other places (the structure layout
72 // code).
73
74 /// Compute an offset to the given ivar, suitable for passing to
75 /// EmitValueForIvarAtOffset. Note that the correct handling of
76 /// bit-fields is carefully coordinated by these two, use caution!
77 ///
78 /// The latter overload is suitable for computing the offset of a
79 /// sythesized ivar.
80 uint64_t ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
81 const ObjCInterfaceDecl *OID,
82 const ObjCIvarDecl *Ivar);
83 uint64_t ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,
84 const ObjCImplementationDecl *OID,
85 const ObjCIvarDecl *Ivar);
86
87 LValue EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,
88 const ObjCInterfaceDecl *OID,
89 llvm::Value *BaseValue,
90 const ObjCIvarDecl *Ivar,
91 unsigned CVRQualifiers, llvm::Value *Offset);
92 /// Emits a try / catch statement. This function is intended to be called by
93 /// subclasses, and provides a generic mechanism for generating these, which
94 /// should be usable by all runtimes. The caller must provide the functions
95 /// to call when entering and exiting a \@catch() block, and the function
96 /// used to rethrow exceptions. If the begin and end catch functions are
97 /// NULL, then the function assumes that the EH personality function provides
98 /// the thrown object directly.
99 void EmitTryCatchStmt(CodeGenFunction &CGF, const ObjCAtTryStmt &S,
100 llvm::FunctionCallee beginCatchFn,
101 llvm::FunctionCallee endCatchFn,
102 llvm::FunctionCallee exceptionRethrowFn);
103
104 void EmitInitOfCatchParam(CodeGenFunction &CGF, llvm::Value *exn,
105 const VarDecl *paramDecl);
106
107 /// Emits an \@synchronize() statement, using the \p syncEnterFn and
108 /// \p syncExitFn arguments as the functions called to lock and unlock
109 /// the object. This function can be called by subclasses that use
110 /// zero-cost exception handling.
111 void EmitAtSynchronizedStmt(CodeGenFunction &CGF,
112 const ObjCAtSynchronizedStmt &S,
113 llvm::FunctionCallee syncEnterFn,
114 llvm::FunctionCallee syncExitFn);
115
116public:
117 virtual ~CGObjCRuntime();
118
119 std::string getSymbolNameForMethod(const ObjCMethodDecl *method,
120 bool includeCategoryName = true,
121 bool includePrefixByte = true);
122
123 /// Generate the function required to register all Objective-C components in
124 /// this compilation unit with the runtime library.
125 virtual llvm::Function *ModuleInitFunction() = 0;
126
127 /// Get a selector for the specified name and type values.
128 /// The result should have the LLVM type for ASTContext::getObjCSelType().
129 virtual llvm::Value *GetSelector(CodeGenFunction &CGF, Selector Sel) = 0;
130
131 /// Get the address of a selector for the specified name and type values.
132 /// This is a rarely-used language extension, but sadly it exists.
133 ///
134 /// The result should have the LLVM type for a pointer to
135 /// ASTContext::getObjCSelType().
136 virtual Address GetAddrOfSelector(CodeGenFunction &CGF, Selector Sel) = 0;
137
138 /// Get a typed selector.
139 virtual llvm::Value *GetSelector(CodeGenFunction &CGF,
140 const ObjCMethodDecl *Method) = 0;
141
142 /// Get the type constant to catch for the given ObjC pointer type.
143 /// This is used externally to implement catching ObjC types in C++.
144 /// Runtimes which don't support this should add the appropriate
145 /// error to Sema.
146 virtual llvm::Constant *GetEHType(QualType T) = 0;
147
148 virtual CatchTypeInfo getCatchAllTypeInfo() { return {.RTTI: nullptr, .Flags: 0}; }
149
150 /// Generate a constant string object.
151 virtual ConstantAddress GenerateConstantString(const StringLiteral *) = 0;
152
153 /// Generate a category. A category contains a list of methods (and
154 /// accompanying metadata) and a list of protocols.
155 virtual void GenerateCategory(const ObjCCategoryImplDecl *OCD) = 0;
156
157 /// Generate a class structure for this class.
158 virtual void GenerateClass(const ObjCImplementationDecl *OID) = 0;
159
160 /// Register an class alias.
161 virtual void RegisterAlias(const ObjCCompatibleAliasDecl *OAD) = 0;
162
163 /// Generate an Objective-C message send operation.
164 ///
165 /// \param Method - The method being called, this may be null if synthesizing
166 /// a property setter or getter.
167 virtual CodeGen::RValue
168 GenerateMessageSend(CodeGen::CodeGenFunction &CGF, ReturnValueSlot ReturnSlot,
169 QualType ResultType, Selector Sel, llvm::Value *Receiver,
170 const CallArgList &CallArgs,
171 const ObjCInterfaceDecl *Class = nullptr,
172 const ObjCMethodDecl *Method = nullptr) = 0;
173
174 /// Generate an Objective-C message send operation.
175 ///
176 /// This variant allows for the call to be substituted with an optimized
177 /// variant.
178 CodeGen::RValue GeneratePossiblySpecializedMessageSend(
179 CodeGenFunction &CGF, ReturnValueSlot Return, QualType ResultType,
180 Selector Sel, llvm::Value *Receiver, const CallArgList &Args,
181 const ObjCInterfaceDecl *OID, const ObjCMethodDecl *Method,
182 bool isClassMessage);
183
184 /// Generate an Objective-C message send operation to the super
185 /// class initiated in a method for Class and with the given Self
186 /// object.
187 ///
188 /// \param Method - The method being called, this may be null if synthesizing
189 /// a property setter or getter.
190 virtual CodeGen::RValue GenerateMessageSendSuper(
191 CodeGen::CodeGenFunction &CGF, ReturnValueSlot ReturnSlot,
192 QualType ResultType, Selector Sel, const ObjCInterfaceDecl *Class,
193 bool isCategoryImpl, llvm::Value *Self, bool IsClassMessage,
194 const CallArgList &CallArgs, const ObjCMethodDecl *Method = nullptr) = 0;
195
196 /// Walk the list of protocol references from a class, category or
197 /// protocol to traverse the DAG formed from it's inheritance hierarchy. Find
198 /// the list of protocols that ends each walk at either a runtime
199 /// protocol or a non-runtime protocol with no parents. For the common case of
200 /// just a list of standard runtime protocols this just returns the same list
201 /// that was passed in.
202 std::vector<const ObjCProtocolDecl *>
203 GetRuntimeProtocolList(ObjCProtocolDecl::protocol_iterator begin,
204 ObjCProtocolDecl::protocol_iterator end);
205
206 /// Emit the code to return the named protocol as an object, as in a
207 /// \@protocol expression.
208 virtual llvm::Value *GenerateProtocolRef(CodeGenFunction &CGF,
209 const ObjCProtocolDecl *OPD) = 0;
210
211 /// Generate the named protocol. Protocols contain method metadata but no
212 /// implementations.
213 virtual void GenerateProtocol(const ObjCProtocolDecl *OPD) = 0;
214
215 /// GetOrEmitProtocol - Get the protocol object for the given
216 /// declaration, emitting it if necessary. The return value has type
217 /// ProtocolPtrTy.
218 virtual llvm::Constant *GetOrEmitProtocol(const ObjCProtocolDecl *PD) = 0;
219
220 /// Generate a function preamble for a method with the specified
221 /// types.
222
223 // FIXME: Current this just generates the Function definition, but really this
224 // should also be generating the loads of the parameters, as the runtime
225 // should have full control over how parameters are passed.
226 virtual llvm::Function *GenerateMethod(const ObjCMethodDecl *OMD,
227 const ObjCContainerDecl *CD) = 0;
228
229 /// Generates precondition checks for direct Objective-C Methods.
230 /// This includes [self self] for class methods and nil checks.
231 virtual void GenerateDirectMethodsPreconditionCheck(
232 CodeGenFunction &CGF, llvm::Function *Fn, const ObjCMethodDecl *OMD,
233 const ObjCContainerDecl *CD) = 0;
234
235 /// Generates prologue for direct Objective-C Methods.
236 virtual void GenerateDirectMethodPrologue(CodeGenFunction &CGF,
237 llvm::Function *Fn,
238 const ObjCMethodDecl *OMD,
239 const ObjCContainerDecl *CD) = 0;
240
241 /// Return the runtime function for getting properties.
242 virtual llvm::FunctionCallee GetPropertyGetFunction() = 0;
243
244 /// Return the runtime function for setting properties.
245 virtual llvm::FunctionCallee GetPropertySetFunction() = 0;
246
247 /// Return the runtime function for optimized setting properties.
248 virtual llvm::FunctionCallee GetOptimizedPropertySetFunction(bool atomic,
249 bool copy) = 0;
250
251 // API for atomic copying of qualified aggregates in getter.
252 virtual llvm::FunctionCallee GetGetStructFunction() = 0;
253 // API for atomic copying of qualified aggregates in setter.
254 virtual llvm::FunctionCallee GetSetStructFunction() = 0;
255 /// API for atomic copying of qualified aggregates with non-trivial copy
256 /// assignment (c++) in setter.
257 virtual llvm::FunctionCallee GetCppAtomicObjectSetFunction() = 0;
258 /// API for atomic copying of qualified aggregates with non-trivial copy
259 /// assignment (c++) in getter.
260 virtual llvm::FunctionCallee GetCppAtomicObjectGetFunction() = 0;
261
262 /// GetClass - Return a reference to the class for the given
263 /// interface decl.
264 virtual llvm::Value *GetClass(CodeGenFunction &CGF,
265 const ObjCInterfaceDecl *OID) = 0;
266
267 virtual llvm::Value *EmitNSAutoreleasePoolClassRef(CodeGenFunction &CGF) {
268 llvm_unreachable("autoreleasepool unsupported in this ABI");
269 }
270
271 /// EnumerationMutationFunction - Return the function that's called by the
272 /// compiler when a mutation is detected during foreach iteration.
273 virtual llvm::FunctionCallee EnumerationMutationFunction() = 0;
274
275 virtual void EmitSynchronizedStmt(CodeGen::CodeGenFunction &CGF,
276 const ObjCAtSynchronizedStmt &S) = 0;
277 virtual void EmitTryStmt(CodeGen::CodeGenFunction &CGF,
278 const ObjCAtTryStmt &S) = 0;
279 virtual void EmitThrowStmt(CodeGen::CodeGenFunction &CGF,
280 const ObjCAtThrowStmt &S,
281 bool ClearInsertionPoint = true) = 0;
282 virtual llvm::Value *EmitObjCWeakRead(CodeGen::CodeGenFunction &CGF,
283 Address AddrWeakObj) = 0;
284 virtual void EmitObjCWeakAssign(CodeGen::CodeGenFunction &CGF,
285 llvm::Value *src, Address dest) = 0;
286 virtual void EmitObjCGlobalAssign(CodeGen::CodeGenFunction &CGF,
287 llvm::Value *src, Address dest,
288 bool threadlocal = false) = 0;
289 virtual void EmitObjCIvarAssign(CodeGen::CodeGenFunction &CGF,
290 llvm::Value *src, Address dest,
291 llvm::Value *ivarOffset) = 0;
292 virtual void EmitObjCStrongCastAssign(CodeGen::CodeGenFunction &CGF,
293 llvm::Value *src, Address dest) = 0;
294
295 virtual LValue EmitObjCValueForIvar(CodeGen::CodeGenFunction &CGF,
296 QualType ObjectTy, llvm::Value *BaseValue,
297 const ObjCIvarDecl *Ivar,
298 unsigned CVRQualifiers) = 0;
299 virtual llvm::Value *EmitIvarOffset(CodeGen::CodeGenFunction &CGF,
300 const ObjCInterfaceDecl *Interface,
301 const ObjCIvarDecl *Ivar) = 0;
302 virtual void EmitGCMemmoveCollectable(CodeGen::CodeGenFunction &CGF,
303 Address DestPtr, Address SrcPtr,
304 llvm::Value *Size) = 0;
305 virtual llvm::Constant *
306 BuildGCBlockLayout(CodeGen::CodeGenModule &CGM,
307 const CodeGen::CGBlockInfo &blockInfo) = 0;
308 virtual llvm::Constant *
309 BuildRCBlockLayout(CodeGen::CodeGenModule &CGM,
310 const CodeGen::CGBlockInfo &blockInfo) = 0;
311 virtual std::string getRCBlockLayoutStr(CodeGen::CodeGenModule &CGM,
312 const CGBlockInfo &blockInfo) {
313 return {};
314 }
315
316 /// Returns an i8* which points to the byref layout information.
317 virtual llvm::Constant *BuildByrefLayout(CodeGen::CodeGenModule &CGM,
318 QualType T) = 0;
319
320 struct MessageSendInfo {
321 const CGFunctionInfo &CallInfo;
322 llvm::PointerType *MessengerType;
323
324 MessageSendInfo(const CGFunctionInfo &callInfo,
325 llvm::PointerType *messengerType)
326 : CallInfo(callInfo), MessengerType(messengerType) {}
327 };
328
329 MessageSendInfo getMessageSendInfo(const ObjCMethodDecl *method,
330 QualType resultType,
331 CallArgList &callArgs);
332
333 bool canMessageReceiverBeNull(CodeGenFunction &CGF,
334 const ObjCMethodDecl *method, bool isSuper,
335 const ObjCInterfaceDecl *classReceiver,
336 llvm::Value *receiver);
337
338 static bool isWeakLinkedClass(const ObjCInterfaceDecl *cls);
339
340 /// Destroy the callee-destroyed arguments of the given method,
341 /// if it has any. Used for nil-receiver paths in message sends.
342 /// Never does anything if the method does not satisfy
343 /// hasParamDestroyedInCallee().
344 ///
345 /// \param callArgs - just the formal arguments, not including implicit
346 /// arguments such as self and cmd
347 static void destroyCalleeDestroyedArguments(CodeGenFunction &CGF,
348 const ObjCMethodDecl *method,
349 const CallArgList &callArgs);
350
351 // FIXME: This probably shouldn't be here, but the code to compute
352 // it is here.
353 unsigned ComputeBitfieldBitOffset(CodeGen::CodeGenModule &CGM,
354 const ObjCInterfaceDecl *ID,
355 const ObjCIvarDecl *Ivar);
356};
357
358/// Creates an instance of an Objective-C runtime class.
359// TODO: This should include some way of selecting which runtime to target.
360CGObjCRuntime *CreateGNUObjCRuntime(CodeGenModule &CGM);
361CGObjCRuntime *CreateMacObjCRuntime(CodeGenModule &CGM);
362} // namespace CodeGen
363} // namespace clang
364#endif
365