//===----- CGObjCRuntime.h - Interface to ObjC Runtimes ---------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This provides an abstract class for Objective-C code generation.  Concrete

// subclasses of this implement code generation for specific Objective-C

// runtime libraries.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_LIB_CODEGEN_CGOBJCRUNTIME_H

#define LLVM_CLANG_LIB_CODEGEN_CGOBJCRUNTIME_H

#include "CGBuilder.h"

#include "CGCall.h"

#include "CGCleanup.h"

#include "CGValue.h"

#include "clang/AST/DeclObjC.h"

#include "clang/Basic/IdentifierTable.h" // Selector

#include "llvm/ADT/UniqueVector.h"

namespace llvm {

  class Constant;

  class Function;

  class Module;

  class StructLayout;

  class StructType;

  class Type;

  class Value;

}

namespace clang {

namespace CodeGen {

  class CodeGenFunction;

}

  class FieldDecl;

  class ObjCAtTryStmt;

  class ObjCAtThrowStmt;

  class ObjCAtSynchronizedStmt;

  class ObjCContainerDecl;

  class ObjCCategoryImplDecl;

  class ObjCImplementationDecl;

  class ObjCInterfaceDecl;

  class ObjCMessageExpr;

  class ObjCMethodDecl;

  class ObjCProtocolDecl;

  class Selector;

  class ObjCIvarDecl;

  class ObjCStringLiteral;

  class BlockDeclRefExpr;

namespace CodeGen {

  class CodeGenModule;

  class CGBlockInfo;

// FIXME: Several methods should be pure virtual but aren't to avoid the

// partially-implemented subclass breaking.

/// Implements runtime-specific code generation functions.

class CGObjCRuntime {

protected:

  CodeGen::CodeGenModule &CGM;

  CGObjCRuntime(CodeGen::CodeGenModule &CGM) : CGM(CGM) {}

  // Utility functions for unified ivar access. These need to

  // eventually be folded into other places (the structure layout

  // code).

  /// Compute an offset to the given ivar, suitable for passing to

  /// EmitValueForIvarAtOffset.  Note that the correct handling of

  /// bit-fields is carefully coordinated by these two, use caution!

  ///

  /// The latter overload is suitable for computing the offset of a

  /// sythesized ivar.

  uint64_t ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,

                                 const ObjCInterfaceDecl *OID,

                                 const ObjCIvarDecl *Ivar);

  uint64_t ComputeIvarBaseOffset(CodeGen::CodeGenModule &CGM,

                                 const ObjCImplementationDecl *OID,

                                 const ObjCIvarDecl *Ivar);

  LValue EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,

                                  const ObjCInterfaceDecl *OID,

                                  llvm::Value *BaseValue,

                                  const ObjCIvarDecl *Ivar,

                                  unsigned CVRQualifiers,

                                  llvm::Value *Offset);

  /// Emits a try / catch statement.  This function is intended to be called by

  /// subclasses, and provides a generic mechanism for generating these, which

  /// should be usable by all runtimes.  The caller must provide the functions

  /// to call when entering and exiting a \@catch() block, and the function

  /// used to rethrow exceptions.  If the begin and end catch functions are

  /// NULL, then the function assumes that the EH personality function provides

  /// the thrown object directly.

  void EmitTryCatchStmt(CodeGenFunction &CGF, const ObjCAtTryStmt &S,

                        llvm::FunctionCallee beginCatchFn,

                        llvm::FunctionCallee endCatchFn,

                        llvm::FunctionCallee exceptionRethrowFn);

  void EmitInitOfCatchParam(CodeGenFunction &CGF, llvm::Value *exn,

                            const VarDecl *paramDecl);

  /// Emits an \@synchronize() statement, using the \p syncEnterFn and

  /// \p syncExitFn arguments as the functions called to lock and unlock

  /// the object.  This function can be called by subclasses that use

  /// zero-cost exception handling.

  void EmitAtSynchronizedStmt(CodeGenFunction &CGF,

                              const ObjCAtSynchronizedStmt &S,

                              llvm::FunctionCallee syncEnterFn,

                              llvm::FunctionCallee syncExitFn);

public:

  virtual ~CGObjCRuntime();

  std::string getSymbolNameForMethod(const ObjCMethodDecl *method,

                                     bool includeCategoryName = true);

  /// Generate the function required to register all Objective-C components in

  /// this compilation unit with the runtime library.

  virtual llvm::Function *ModuleInitFunction() = 0;

  /// Get a selector for the specified name and type values.

  /// The result should have the LLVM type for ASTContext::getObjCSelType().

  virtual llvm::Value *GetSelector(CodeGenFunction &CGF, Selector Sel) = 0;

  /// Get the address of a selector for the specified name and type values.

  /// This is a rarely-used language extension, but sadly it exists.

  ///

  /// The result should have the LLVM type for a pointer to

  /// ASTContext::getObjCSelType().

  virtual Address GetAddrOfSelector(CodeGenFunction &CGF, Selector Sel) = 0;

  /// Get a typed selector.

  virtual llvm::Value *GetSelector(CodeGenFunction &CGF,

                                   const ObjCMethodDecl *Method) = 0;

  /// Get the type constant to catch for the given ObjC pointer type.

  /// This is used externally to implement catching ObjC types in C++.

  /// Runtimes which don't support this should add the appropriate

  /// error to Sema.

  virtual llvm::Constant *GetEHType(QualType T) = 0;

  virtual CatchTypeInfo getCatchAllTypeInfo() { return { nullptr, 0 }; }

  /// Generate a constant string object.

  virtual ConstantAddress GenerateConstantString(const StringLiteral *) = 0;

  /// Generate a category.  A category contains a list of methods (and

  /// accompanying metadata) and a list of protocols.

  virtual void GenerateCategory(const ObjCCategoryImplDecl *OCD) = 0;

  /// Generate a class structure for this class.

  virtual void GenerateClass(const ObjCImplementationDecl *OID) = 0;

  /// Register an class alias.

  virtual void RegisterAlias(const ObjCCompatibleAliasDecl *OAD) = 0;

  /// Generate an Objective-C message send operation.

  ///

  /// \param Method - The method being called, this may be null if synthesizing

  /// a property setter or getter.

  virtual CodeGen::RValue

  GenerateMessageSend(CodeGen::CodeGenFunction &CGF,

                      ReturnValueSlot ReturnSlot,

                      QualType ResultType,

                      Selector Sel,

                      llvm::Value *Receiver,

                      const CallArgList &CallArgs,

                      const ObjCInterfaceDecl *Class = nullptr,

                      const ObjCMethodDecl *Method = nullptr) = 0;

  /// Generate an Objective-C message send operation.

  ///

  /// This variant allows for the call to be substituted with an optimized

  /// variant.

  CodeGen::RValue

  GeneratePossiblySpecializedMessageSend(CodeGenFunction &CGF,

                                         ReturnValueSlot Return,

                                         QualType ResultType,

                                         Selector Sel,

                                         llvm::Value *Receiver,

                                         const CallArgList& Args,

                                         const ObjCInterfaceDecl *OID,

                                         const ObjCMethodDecl *Method,

                                         bool isClassMessage);

  /// Generate an Objective-C message send operation to the super

  /// class initiated in a method for Class and with the given Self

  /// object.

  ///

  /// \param Method - The method being called, this may be null if synthesizing

  /// a property setter or getter.

  virtual CodeGen::RValue

  GenerateMessageSendSuper(CodeGen::CodeGenFunction &CGF,

                           ReturnValueSlot ReturnSlot,

                           QualType ResultType,

                           Selector Sel,

                           const ObjCInterfaceDecl *Class,

                           bool isCategoryImpl,

                           llvm::Value *Self,

                           bool IsClassMessage,

                           const CallArgList &CallArgs,

                           const ObjCMethodDecl *Method = nullptr) = 0;

  /// Walk the list of protocol references from a class, category or

  /// protocol to traverse the DAG formed from it's inheritance hierarchy. Find

  /// the list of protocols that ends each walk at either a runtime

  /// protocol or a non-runtime protocol with no parents. For the common case of

  /// just a list of standard runtime protocols this just returns the same list

  /// that was passed in.

  std::vector<const ObjCProtocolDecl *>

  GetRuntimeProtocolList(ObjCProtocolDecl::protocol_iterator begin,

                         ObjCProtocolDecl::protocol_iterator end);

  /// Emit the code to return the named protocol as an object, as in a

  /// \@protocol expression.

  virtual llvm::Value *GenerateProtocolRef(CodeGenFunction &CGF,

                                           const ObjCProtocolDecl *OPD) = 0;

  /// Generate the named protocol.  Protocols contain method metadata but no

  /// implementations.

  virtual void GenerateProtocol(const ObjCProtocolDecl *OPD) = 0;

  /// GetOrEmitProtocol - Get the protocol object for the given

  /// declaration, emitting it if necessary. The return value has type

  /// ProtocolPtrTy.

  virtual llvm::Constant *GetOrEmitProtocol(const ObjCProtocolDecl *PD) = 0;

  /// Generate a function preamble for a method with the specified

  /// types.

  // FIXME: Current this just generates the Function definition, but really this

  // should also be generating the loads of the parameters, as the runtime

  // should have full control over how parameters are passed.

  virtual llvm::Function *GenerateMethod(const ObjCMethodDecl *OMD,

                                         const ObjCContainerDecl *CD) = 0;

  /// Generates prologue for direct Objective-C Methods.

  virtual void GenerateDirectMethodPrologue(CodeGenFunction &CGF,

                                            llvm::Function *Fn,

                                            const ObjCMethodDecl *OMD,

                                            const ObjCContainerDecl *CD) = 0;

  /// Return the runtime function for getting properties.

  virtual llvm::FunctionCallee GetPropertyGetFunction() = 0;

  /// Return the runtime function for setting properties.

  virtual llvm::FunctionCallee GetPropertySetFunction() = 0;

  /// Return the runtime function for optimized setting properties.

  virtual llvm::FunctionCallee GetOptimizedPropertySetFunction(bool atomic,

                                                               bool copy) = 0;

  // API for atomic copying of qualified aggregates in getter.

  virtual llvm::FunctionCallee GetGetStructFunction() = 0;

  // API for atomic copying of qualified aggregates in setter.

  virtual llvm::FunctionCallee GetSetStructFunction() = 0;

  /// API for atomic copying of qualified aggregates with non-trivial copy

  /// assignment (c++) in setter.

  virtual llvm::FunctionCallee GetCppAtomicObjectSetFunction() = 0;

  /// API for atomic copying of qualified aggregates with non-trivial copy

  /// assignment (c++) in getter.

  virtual llvm::FunctionCallee GetCppAtomicObjectGetFunction() = 0;

  /// GetClass - Return a reference to the class for the given

  /// interface decl.

  virtual llvm::Value *GetClass(CodeGenFunction &CGF,

                                const ObjCInterfaceDecl *OID) = 0;

  virtual llvm::Value *EmitNSAutoreleasePoolClassRef(CodeGenFunction &CGF) {

    llvm_unreachable("autoreleasepool unsupported in this ABI");

  }

  /// EnumerationMutationFunction - Return the function that's called by the

  /// compiler when a mutation is detected during foreach iteration.

  virtual llvm::FunctionCallee EnumerationMutationFunction() = 0;

  virtual void EmitSynchronizedStmt(CodeGen::CodeGenFunction &CGF,

                                    const ObjCAtSynchronizedStmt &S) = 0;

  virtual void EmitTryStmt(CodeGen::CodeGenFunction &CGF,

                           const ObjCAtTryStmt &S) = 0;

  virtual void EmitThrowStmt(CodeGen::CodeGenFunction &CGF,

                             const ObjCAtThrowStmt &S,

                             bool ClearInsertionPoint=true) = 0;

  virtual llvm::Value *EmitObjCWeakRead(CodeGen::CodeGenFunction &CGF,

                                        Address AddrWeakObj) = 0;

  virtual void EmitObjCWeakAssign(CodeGen::CodeGenFunction &CGF,

                                  llvm::Value *src, Address dest) = 0;

  virtual void EmitObjCGlobalAssign(CodeGen::CodeGenFunction &CGF,

                                    llvm::Value *src, Address dest,

                                    bool threadlocal=false) = 0;

  virtual void EmitObjCIvarAssign(CodeGen::CodeGenFunction &CGF,

                                  llvm::Value *src, Address dest,

                                  llvm::Value *ivarOffset) = 0;

  virtual void EmitObjCStrongCastAssign(CodeGen::CodeGenFunction &CGF,

                                        llvm::Value *src, Address dest) = 0;

  virtual LValue EmitObjCValueForIvar(CodeGen::CodeGenFunction &CGF,

                                      QualType ObjectTy,

                                      llvm::Value *BaseValue,

                                      const ObjCIvarDecl *Ivar,

                                      unsigned CVRQualifiers) = 0;

  virtual llvm::Value *EmitIvarOffset(CodeGen::CodeGenFunction &CGF,

                                      const ObjCInterfaceDecl *Interface,

                                      const ObjCIvarDecl *Ivar) = 0;

  virtual void EmitGCMemmoveCollectable(CodeGen::CodeGenFunction &CGF,

                                        Address DestPtr,

                                        Address SrcPtr,

                                        llvm::Value *Size) = 0;

  virtual llvm::Constant *BuildGCBlockLayout(CodeGen::CodeGenModule &CGM,

                                  const CodeGen::CGBlockInfo &blockInfo) = 0;

  virtual llvm::Constant *BuildRCBlockLayout(CodeGen::CodeGenModule &CGM,

                                  const CodeGen::CGBlockInfo &blockInfo) = 0;

  virtual std::string getRCBlockLayoutStr(CodeGen::CodeGenModule &CGM,

                                          const CGBlockInfo &blockInfo) {

    return {};

  }

  /// Returns an i8* which points to the byref layout information.

  virtual llvm::Constant *BuildByrefLayout(CodeGen::CodeGenModule &CGM,

                                           QualType T) = 0;

  struct MessageSendInfo {

    const CGFunctionInfo &CallInfo;

    llvm::PointerType *MessengerType;

    MessageSendInfo(const CGFunctionInfo &callInfo,

                    llvm::PointerType *messengerType)

      : CallInfo(callInfo), MessengerType(messengerType) {}

  };

  MessageSendInfo getMessageSendInfo(const ObjCMethodDecl *method,

                                     QualType resultType,

                                     CallArgList &callArgs);

  bool canMessageReceiverBeNull(CodeGenFunction &CGF,

                                const ObjCMethodDecl *method,

                                bool isSuper,

                                const ObjCInterfaceDecl *classReceiver,

                                llvm::Value *receiver);

  static bool isWeakLinkedClass(const ObjCInterfaceDecl *cls);

  /// Destroy the callee-destroyed arguments of the given method,

  /// if it has any.  Used for nil-receiver paths in message sends.

  /// Never does anything if the method does not satisfy

  /// hasParamDestroyedInCallee().

  ///

  /// \param callArgs - just the formal arguments, not including implicit

  ///   arguments such as self and cmd

  static void destroyCalleeDestroyedArguments(CodeGenFunction &CGF,

                                              const ObjCMethodDecl *method,

                                              const CallArgList &callArgs);

  // FIXME: This probably shouldn't be here, but the code to compute

  // it is here.

  unsigned ComputeBitfieldBitOffset(CodeGen::CodeGenModule &CGM,

                                    const ObjCInterfaceDecl *ID,

                                    const ObjCIvarDecl *Ivar);

};

/// Creates an instance of an Objective-C runtime class.

//TODO: This should include some way of selecting which runtime to target.

CGObjCRuntime *CreateGNUObjCRuntime(CodeGenModule &CGM);

CGObjCRuntime *CreateMacObjCRuntime(CodeGenModule &CGM);

}

}

#endif