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 25 namespace llvm { 26 class Constant; 27 class Function; 28 class Module; 29 class StructLayout; 30 class StructType; 31 class Type; 32 class Value; 33 } // namespace llvm 34 35 namespace clang { 36 namespace CodeGen { 37 class CGFunctionInfo; 38 class CodeGenFunction; 39 } // namespace CodeGen 40 41 class FieldDecl; 42 class ObjCAtTryStmt; 43 class ObjCAtThrowStmt; 44 class ObjCAtSynchronizedStmt; 45 class ObjCContainerDecl; 46 class ObjCCategoryImplDecl; 47 class ObjCImplementationDecl; 48 class ObjCInterfaceDecl; 49 class ObjCMessageExpr; 50 class ObjCMethodDecl; 51 class ObjCProtocolDecl; 52 class Selector; 53 class ObjCIvarDecl; 54 class ObjCStringLiteral; 55 class BlockDeclRefExpr; 56 57 namespace CodeGen { 58 class CodeGenModule; 59 class 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. 65 class CGObjCRuntime { 66 protected: 67 CodeGen::CodeGenModule &CGM; CGObjCRuntime(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); 115 116 public: 117 virtual ~CGObjCRuntime(); 118 119 std::string getSymbolNameForMethod(const ObjCMethodDecl *method, 120 bool includeCategoryName = true); 121 122 /// Generate the function required to register all Objective-C components in 123 /// this compilation unit with the runtime library. 124 virtual llvm::Function *ModuleInitFunction() = 0; 125 126 /// Get a selector for the specified name and type values. 127 /// The result should have the LLVM type for ASTContext::getObjCSelType(). 128 virtual llvm::Value *GetSelector(CodeGenFunction &CGF, Selector Sel) = 0; 129 130 /// Get the address of a selector for the specified name and type values. 131 /// This is a rarely-used language extension, but sadly it exists. 132 /// 133 /// The result should have the LLVM type for a pointer to 134 /// ASTContext::getObjCSelType(). 135 virtual Address GetAddrOfSelector(CodeGenFunction &CGF, Selector Sel) = 0; 136 137 /// Get a typed selector. 138 virtual llvm::Value *GetSelector(CodeGenFunction &CGF, 139 const ObjCMethodDecl *Method) = 0; 140 141 /// Get the type constant to catch for the given ObjC pointer type. 142 /// This is used externally to implement catching ObjC types in C++. 143 /// Runtimes which don't support this should add the appropriate 144 /// error to Sema. 145 virtual llvm::Constant *GetEHType(QualType T) = 0; 146 getCatchAllTypeInfo()147 virtual CatchTypeInfo getCatchAllTypeInfo() { return {nullptr, 0}; } 148 149 /// Generate a constant string object. 150 virtual ConstantAddress GenerateConstantString(const StringLiteral *) = 0; 151 152 /// Generate a category. A category contains a list of methods (and 153 /// accompanying metadata) and a list of protocols. 154 virtual void GenerateCategory(const ObjCCategoryImplDecl *OCD) = 0; 155 156 /// Generate a class structure for this class. 157 virtual void GenerateClass(const ObjCImplementationDecl *OID) = 0; 158 159 /// Register an class alias. 160 virtual void RegisterAlias(const ObjCCompatibleAliasDecl *OAD) = 0; 161 162 /// Generate an Objective-C message send operation. 163 /// 164 /// \param Method - The method being called, this may be null if synthesizing 165 /// a property setter or getter. 166 virtual CodeGen::RValue 167 GenerateMessageSend(CodeGen::CodeGenFunction &CGF, ReturnValueSlot ReturnSlot, 168 QualType ResultType, Selector Sel, llvm::Value *Receiver, 169 const CallArgList &CallArgs, 170 const ObjCInterfaceDecl *Class = nullptr, 171 const ObjCMethodDecl *Method = nullptr) = 0; 172 173 /// Generate an Objective-C message send operation. 174 /// 175 /// This variant allows for the call to be substituted with an optimized 176 /// variant. 177 CodeGen::RValue GeneratePossiblySpecializedMessageSend( 178 CodeGenFunction &CGF, ReturnValueSlot Return, QualType ResultType, 179 Selector Sel, llvm::Value *Receiver, const CallArgList &Args, 180 const ObjCInterfaceDecl *OID, const ObjCMethodDecl *Method, 181 bool isClassMessage); 182 183 /// Generate an Objective-C message send operation to the super 184 /// class initiated in a method for Class and with the given Self 185 /// object. 186 /// 187 /// \param Method - The method being called, this may be null if synthesizing 188 /// a property setter or getter. 189 virtual CodeGen::RValue GenerateMessageSendSuper( 190 CodeGen::CodeGenFunction &CGF, ReturnValueSlot ReturnSlot, 191 QualType ResultType, Selector Sel, const ObjCInterfaceDecl *Class, 192 bool isCategoryImpl, llvm::Value *Self, bool IsClassMessage, 193 const CallArgList &CallArgs, const ObjCMethodDecl *Method = nullptr) = 0; 194 195 /// Walk the list of protocol references from a class, category or 196 /// protocol to traverse the DAG formed from it's inheritance hierarchy. Find 197 /// the list of protocols that ends each walk at either a runtime 198 /// protocol or a non-runtime protocol with no parents. For the common case of 199 /// just a list of standard runtime protocols this just returns the same list 200 /// that was passed in. 201 std::vector<const ObjCProtocolDecl *> 202 GetRuntimeProtocolList(ObjCProtocolDecl::protocol_iterator begin, 203 ObjCProtocolDecl::protocol_iterator end); 204 205 /// Emit the code to return the named protocol as an object, as in a 206 /// \@protocol expression. 207 virtual llvm::Value *GenerateProtocolRef(CodeGenFunction &CGF, 208 const ObjCProtocolDecl *OPD) = 0; 209 210 /// Generate the named protocol. Protocols contain method metadata but no 211 /// implementations. 212 virtual void GenerateProtocol(const ObjCProtocolDecl *OPD) = 0; 213 214 /// GetOrEmitProtocol - Get the protocol object for the given 215 /// declaration, emitting it if necessary. The return value has type 216 /// ProtocolPtrTy. 217 virtual llvm::Constant *GetOrEmitProtocol(const ObjCProtocolDecl *PD) = 0; 218 219 /// Generate a function preamble for a method with the specified 220 /// types. 221 222 // FIXME: Current this just generates the Function definition, but really this 223 // should also be generating the loads of the parameters, as the runtime 224 // should have full control over how parameters are passed. 225 virtual llvm::Function *GenerateMethod(const ObjCMethodDecl *OMD, 226 const ObjCContainerDecl *CD) = 0; 227 228 /// Generates prologue for direct Objective-C Methods. 229 virtual void GenerateDirectMethodPrologue(CodeGenFunction &CGF, 230 llvm::Function *Fn, 231 const ObjCMethodDecl *OMD, 232 const ObjCContainerDecl *CD) = 0; 233 234 /// Return the runtime function for getting properties. 235 virtual llvm::FunctionCallee GetPropertyGetFunction() = 0; 236 237 /// Return the runtime function for setting properties. 238 virtual llvm::FunctionCallee GetPropertySetFunction() = 0; 239 240 /// Return the runtime function for optimized setting properties. 241 virtual llvm::FunctionCallee GetOptimizedPropertySetFunction(bool atomic, 242 bool copy) = 0; 243 244 // API for atomic copying of qualified aggregates in getter. 245 virtual llvm::FunctionCallee GetGetStructFunction() = 0; 246 // API for atomic copying of qualified aggregates in setter. 247 virtual llvm::FunctionCallee GetSetStructFunction() = 0; 248 /// API for atomic copying of qualified aggregates with non-trivial copy 249 /// assignment (c++) in setter. 250 virtual llvm::FunctionCallee GetCppAtomicObjectSetFunction() = 0; 251 /// API for atomic copying of qualified aggregates with non-trivial copy 252 /// assignment (c++) in getter. 253 virtual llvm::FunctionCallee GetCppAtomicObjectGetFunction() = 0; 254 255 /// GetClass - Return a reference to the class for the given 256 /// interface decl. 257 virtual llvm::Value *GetClass(CodeGenFunction &CGF, 258 const ObjCInterfaceDecl *OID) = 0; 259 EmitNSAutoreleasePoolClassRef(CodeGenFunction & CGF)260 virtual llvm::Value *EmitNSAutoreleasePoolClassRef(CodeGenFunction &CGF) { 261 llvm_unreachable("autoreleasepool unsupported in this ABI"); 262 } 263 264 /// EnumerationMutationFunction - Return the function that's called by the 265 /// compiler when a mutation is detected during foreach iteration. 266 virtual llvm::FunctionCallee EnumerationMutationFunction() = 0; 267 268 virtual void EmitSynchronizedStmt(CodeGen::CodeGenFunction &CGF, 269 const ObjCAtSynchronizedStmt &S) = 0; 270 virtual void EmitTryStmt(CodeGen::CodeGenFunction &CGF, 271 const ObjCAtTryStmt &S) = 0; 272 virtual void EmitThrowStmt(CodeGen::CodeGenFunction &CGF, 273 const ObjCAtThrowStmt &S, 274 bool ClearInsertionPoint = true) = 0; 275 virtual llvm::Value *EmitObjCWeakRead(CodeGen::CodeGenFunction &CGF, 276 Address AddrWeakObj) = 0; 277 virtual void EmitObjCWeakAssign(CodeGen::CodeGenFunction &CGF, 278 llvm::Value *src, Address dest) = 0; 279 virtual void EmitObjCGlobalAssign(CodeGen::CodeGenFunction &CGF, 280 llvm::Value *src, Address dest, 281 bool threadlocal = false) = 0; 282 virtual void EmitObjCIvarAssign(CodeGen::CodeGenFunction &CGF, 283 llvm::Value *src, Address dest, 284 llvm::Value *ivarOffset) = 0; 285 virtual void EmitObjCStrongCastAssign(CodeGen::CodeGenFunction &CGF, 286 llvm::Value *src, Address dest) = 0; 287 288 virtual LValue EmitObjCValueForIvar(CodeGen::CodeGenFunction &CGF, 289 QualType ObjectTy, llvm::Value *BaseValue, 290 const ObjCIvarDecl *Ivar, 291 unsigned CVRQualifiers) = 0; 292 virtual llvm::Value *EmitIvarOffset(CodeGen::CodeGenFunction &CGF, 293 const ObjCInterfaceDecl *Interface, 294 const ObjCIvarDecl *Ivar) = 0; 295 virtual void EmitGCMemmoveCollectable(CodeGen::CodeGenFunction &CGF, 296 Address DestPtr, Address SrcPtr, 297 llvm::Value *Size) = 0; 298 virtual llvm::Constant * 299 BuildGCBlockLayout(CodeGen::CodeGenModule &CGM, 300 const CodeGen::CGBlockInfo &blockInfo) = 0; 301 virtual llvm::Constant * 302 BuildRCBlockLayout(CodeGen::CodeGenModule &CGM, 303 const CodeGen::CGBlockInfo &blockInfo) = 0; getRCBlockLayoutStr(CodeGen::CodeGenModule & CGM,const CGBlockInfo & blockInfo)304 virtual std::string getRCBlockLayoutStr(CodeGen::CodeGenModule &CGM, 305 const CGBlockInfo &blockInfo) { 306 return {}; 307 } 308 309 /// Returns an i8* which points to the byref layout information. 310 virtual llvm::Constant *BuildByrefLayout(CodeGen::CodeGenModule &CGM, 311 QualType T) = 0; 312 313 struct MessageSendInfo { 314 const CGFunctionInfo &CallInfo; 315 llvm::PointerType *MessengerType; 316 MessageSendInfoMessageSendInfo317 MessageSendInfo(const CGFunctionInfo &callInfo, 318 llvm::PointerType *messengerType) 319 : CallInfo(callInfo), MessengerType(messengerType) {} 320 }; 321 322 MessageSendInfo getMessageSendInfo(const ObjCMethodDecl *method, 323 QualType resultType, 324 CallArgList &callArgs); 325 bool canMessageReceiverBeNull(CodeGenFunction &CGF, 326 const ObjCMethodDecl *method, bool isSuper, 327 const ObjCInterfaceDecl *classReceiver, 328 llvm::Value *receiver); 329 static bool isWeakLinkedClass(const ObjCInterfaceDecl *cls); 330 331 /// Destroy the callee-destroyed arguments of the given method, 332 /// if it has any. Used for nil-receiver paths in message sends. 333 /// Never does anything if the method does not satisfy 334 /// hasParamDestroyedInCallee(). 335 /// 336 /// \param callArgs - just the formal arguments, not including implicit 337 /// arguments such as self and cmd 338 static void destroyCalleeDestroyedArguments(CodeGenFunction &CGF, 339 const ObjCMethodDecl *method, 340 const CallArgList &callArgs); 341 342 // FIXME: This probably shouldn't be here, but the code to compute 343 // it is here. 344 unsigned ComputeBitfieldBitOffset(CodeGen::CodeGenModule &CGM, 345 const ObjCInterfaceDecl *ID, 346 const ObjCIvarDecl *Ivar); 347 }; 348 349 /// Creates an instance of an Objective-C runtime class. 350 // TODO: This should include some way of selecting which runtime to target. 351 CGObjCRuntime *CreateGNUObjCRuntime(CodeGenModule &CGM); 352 CGObjCRuntime *CreateMacObjCRuntime(CodeGenModule &CGM); 353 } // namespace CodeGen 354 } // namespace clang 355 #endif 356