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 } 34 35 namespace clang { 36 namespace CodeGen { 37 class CGFunctionInfo; 38 class CodeGenFunction; 39 } 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; 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, 92 llvm::Value *Offset); 93 /// Emits a try / catch statement. This function is intended to be called by 94 /// subclasses, and provides a generic mechanism for generating these, which 95 /// should be usable by all runtimes. The caller must provide the functions 96 /// to call when entering and exiting a \@catch() block, and the function 97 /// used to rethrow exceptions. If the begin and end catch functions are 98 /// NULL, then the function assumes that the EH personality function provides 99 /// the thrown object directly. 100 void EmitTryCatchStmt(CodeGenFunction &CGF, const ObjCAtTryStmt &S, 101 llvm::FunctionCallee beginCatchFn, 102 llvm::FunctionCallee endCatchFn, 103 llvm::FunctionCallee exceptionRethrowFn); 104 105 void EmitInitOfCatchParam(CodeGenFunction &CGF, llvm::Value *exn, 106 const VarDecl *paramDecl); 107 108 /// Emits an \@synchronize() statement, using the \p syncEnterFn and 109 /// \p syncExitFn arguments as the functions called to lock and unlock 110 /// the object. This function can be called by subclasses that use 111 /// zero-cost exception handling. 112 void EmitAtSynchronizedStmt(CodeGenFunction &CGF, 113 const ObjCAtSynchronizedStmt &S, 114 llvm::FunctionCallee syncEnterFn, 115 llvm::FunctionCallee syncExitFn); 116 117 public: 118 virtual ~CGObjCRuntime(); 119 120 std::string getSymbolNameForMethod(const ObjCMethodDecl *method, 121 bool includeCategoryName = 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 { nullptr, 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, 169 ReturnValueSlot ReturnSlot, 170 QualType ResultType, 171 Selector Sel, 172 llvm::Value *Receiver, 173 const CallArgList &CallArgs, 174 const ObjCInterfaceDecl *Class = nullptr, 175 const ObjCMethodDecl *Method = nullptr) = 0; 176 177 /// Generate an Objective-C message send operation. 178 /// 179 /// This variant allows for the call to be substituted with an optimized 180 /// variant. 181 CodeGen::RValue 182 GeneratePossiblySpecializedMessageSend(CodeGenFunction &CGF, 183 ReturnValueSlot Return, 184 QualType ResultType, 185 Selector Sel, 186 llvm::Value *Receiver, 187 const CallArgList& Args, 188 const ObjCInterfaceDecl *OID, 189 const ObjCMethodDecl *Method, 190 bool isClassMessage); 191 192 /// Generate an Objective-C message send operation to the super 193 /// class initiated in a method for Class and with the given Self 194 /// object. 195 /// 196 /// \param Method - The method being called, this may be null if synthesizing 197 /// a property setter or getter. 198 virtual CodeGen::RValue 199 GenerateMessageSendSuper(CodeGen::CodeGenFunction &CGF, 200 ReturnValueSlot ReturnSlot, 201 QualType ResultType, 202 Selector Sel, 203 const ObjCInterfaceDecl *Class, 204 bool isCategoryImpl, 205 llvm::Value *Self, 206 bool IsClassMessage, 207 const CallArgList &CallArgs, 208 const ObjCMethodDecl *Method = nullptr) = 0; 209 210 /// Walk the list of protocol references from a class, category or 211 /// protocol to traverse the DAG formed from it's inheritance hierarchy. Find 212 /// the list of protocols that ends each walk at either a runtime 213 /// protocol or a non-runtime protocol with no parents. For the common case of 214 /// just a list of standard runtime protocols this just returns the same list 215 /// that was passed in. 216 std::vector<const ObjCProtocolDecl *> 217 GetRuntimeProtocolList(ObjCProtocolDecl::protocol_iterator begin, 218 ObjCProtocolDecl::protocol_iterator end); 219 220 /// Emit the code to return the named protocol as an object, as in a 221 /// \@protocol expression. 222 virtual llvm::Value *GenerateProtocolRef(CodeGenFunction &CGF, 223 const ObjCProtocolDecl *OPD) = 0; 224 225 /// Generate the named protocol. Protocols contain method metadata but no 226 /// implementations. 227 virtual void GenerateProtocol(const ObjCProtocolDecl *OPD) = 0; 228 229 /// GetOrEmitProtocol - Get the protocol object for the given 230 /// declaration, emitting it if necessary. The return value has type 231 /// ProtocolPtrTy. 232 virtual llvm::Constant *GetOrEmitProtocol(const ObjCProtocolDecl *PD) = 0; 233 234 /// Generate a function preamble for a method with the specified 235 /// types. 236 237 // FIXME: Current this just generates the Function definition, but really this 238 // should also be generating the loads of the parameters, as the runtime 239 // should have full control over how parameters are passed. 240 virtual llvm::Function *GenerateMethod(const ObjCMethodDecl *OMD, 241 const ObjCContainerDecl *CD) = 0; 242 243 /// Generates prologue for direct Objective-C Methods. 244 virtual void GenerateDirectMethodPrologue(CodeGenFunction &CGF, 245 llvm::Function *Fn, 246 const ObjCMethodDecl *OMD, 247 const ObjCContainerDecl *CD) = 0; 248 249 /// Return the runtime function for getting properties. 250 virtual llvm::FunctionCallee GetPropertyGetFunction() = 0; 251 252 /// Return the runtime function for setting properties. 253 virtual llvm::FunctionCallee GetPropertySetFunction() = 0; 254 255 /// Return the runtime function for optimized setting properties. 256 virtual llvm::FunctionCallee GetOptimizedPropertySetFunction(bool atomic, 257 bool copy) = 0; 258 259 // API for atomic copying of qualified aggregates in getter. 260 virtual llvm::FunctionCallee GetGetStructFunction() = 0; 261 // API for atomic copying of qualified aggregates in setter. 262 virtual llvm::FunctionCallee GetSetStructFunction() = 0; 263 /// API for atomic copying of qualified aggregates with non-trivial copy 264 /// assignment (c++) in setter. 265 virtual llvm::FunctionCallee GetCppAtomicObjectSetFunction() = 0; 266 /// API for atomic copying of qualified aggregates with non-trivial copy 267 /// assignment (c++) in getter. 268 virtual llvm::FunctionCallee GetCppAtomicObjectGetFunction() = 0; 269 270 /// GetClass - Return a reference to the class for the given 271 /// interface decl. 272 virtual llvm::Value *GetClass(CodeGenFunction &CGF, 273 const ObjCInterfaceDecl *OID) = 0; 274 275 276 virtual llvm::Value *EmitNSAutoreleasePoolClassRef(CodeGenFunction &CGF) { 277 llvm_unreachable("autoreleasepool unsupported in this ABI"); 278 } 279 280 /// EnumerationMutationFunction - Return the function that's called by the 281 /// compiler when a mutation is detected during foreach iteration. 282 virtual llvm::FunctionCallee EnumerationMutationFunction() = 0; 283 284 virtual void EmitSynchronizedStmt(CodeGen::CodeGenFunction &CGF, 285 const ObjCAtSynchronizedStmt &S) = 0; 286 virtual void EmitTryStmt(CodeGen::CodeGenFunction &CGF, 287 const ObjCAtTryStmt &S) = 0; 288 virtual void EmitThrowStmt(CodeGen::CodeGenFunction &CGF, 289 const ObjCAtThrowStmt &S, 290 bool ClearInsertionPoint=true) = 0; 291 virtual llvm::Value *EmitObjCWeakRead(CodeGen::CodeGenFunction &CGF, 292 Address AddrWeakObj) = 0; 293 virtual void EmitObjCWeakAssign(CodeGen::CodeGenFunction &CGF, 294 llvm::Value *src, Address dest) = 0; 295 virtual void EmitObjCGlobalAssign(CodeGen::CodeGenFunction &CGF, 296 llvm::Value *src, Address dest, 297 bool threadlocal=false) = 0; 298 virtual void EmitObjCIvarAssign(CodeGen::CodeGenFunction &CGF, 299 llvm::Value *src, Address dest, 300 llvm::Value *ivarOffset) = 0; 301 virtual void EmitObjCStrongCastAssign(CodeGen::CodeGenFunction &CGF, 302 llvm::Value *src, Address dest) = 0; 303 304 virtual LValue EmitObjCValueForIvar(CodeGen::CodeGenFunction &CGF, 305 QualType ObjectTy, 306 llvm::Value *BaseValue, 307 const ObjCIvarDecl *Ivar, 308 unsigned CVRQualifiers) = 0; 309 virtual llvm::Value *EmitIvarOffset(CodeGen::CodeGenFunction &CGF, 310 const ObjCInterfaceDecl *Interface, 311 const ObjCIvarDecl *Ivar) = 0; 312 virtual void EmitGCMemmoveCollectable(CodeGen::CodeGenFunction &CGF, 313 Address DestPtr, 314 Address SrcPtr, 315 llvm::Value *Size) = 0; 316 virtual llvm::Constant *BuildGCBlockLayout(CodeGen::CodeGenModule &CGM, 317 const CodeGen::CGBlockInfo &blockInfo) = 0; 318 virtual llvm::Constant *BuildRCBlockLayout(CodeGen::CodeGenModule &CGM, 319 const CodeGen::CGBlockInfo &blockInfo) = 0; 320 virtual std::string getRCBlockLayoutStr(CodeGen::CodeGenModule &CGM, 321 const CGBlockInfo &blockInfo) { 322 return {}; 323 } 324 325 /// Returns an i8* which points to the byref layout information. 326 virtual llvm::Constant *BuildByrefLayout(CodeGen::CodeGenModule &CGM, 327 QualType T) = 0; 328 329 struct MessageSendInfo { 330 const CGFunctionInfo &CallInfo; 331 llvm::PointerType *MessengerType; 332 333 MessageSendInfo(const CGFunctionInfo &callInfo, 334 llvm::PointerType *messengerType) 335 : CallInfo(callInfo), MessengerType(messengerType) {} 336 }; 337 338 MessageSendInfo getMessageSendInfo(const ObjCMethodDecl *method, 339 QualType resultType, 340 CallArgList &callArgs); 341 bool canMessageReceiverBeNull(CodeGenFunction &CGF, 342 const ObjCMethodDecl *method, 343 bool isSuper, 344 const ObjCInterfaceDecl *classReceiver, 345 llvm::Value *receiver); 346 static bool isWeakLinkedClass(const ObjCInterfaceDecl *cls); 347 348 /// Destroy the callee-destroyed arguments of the given method, 349 /// if it has any. Used for nil-receiver paths in message sends. 350 /// Never does anything if the method does not satisfy 351 /// hasParamDestroyedInCallee(). 352 /// 353 /// \param callArgs - just the formal arguments, not including implicit 354 /// arguments such as self and cmd 355 static void destroyCalleeDestroyedArguments(CodeGenFunction &CGF, 356 const ObjCMethodDecl *method, 357 const CallArgList &callArgs); 358 359 // FIXME: This probably shouldn't be here, but the code to compute 360 // it is here. 361 unsigned ComputeBitfieldBitOffset(CodeGen::CodeGenModule &CGM, 362 const ObjCInterfaceDecl *ID, 363 const ObjCIvarDecl *Ivar); 364 }; 365 366 /// Creates an instance of an Objective-C runtime class. 367 //TODO: This should include some way of selecting which runtime to target. 368 CGObjCRuntime *CreateGNUObjCRuntime(CodeGenModule &CGM); 369 CGObjCRuntime *CreateMacObjCRuntime(CodeGenModule &CGM); 370 } 371 } 372 #endif 373