path: root/lib/CodeGen/CGObjC.cpp

//===---- CGBuiltin.cpp - Emit LLVM Code for builtins ---------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This contains code to emit Objective-C code as LLVM code.
//
//===----------------------------------------------------------------------===//

#include "CGDebugInfo.h"
#include "CGObjCRuntime.h"
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/StmtObjC.h"
#include "clang/Basic/Diagnostic.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Target/TargetData.h"
using namespace clang;
using namespace CodeGen;

/// Emits an instance of NSConstantString representing the object.
llvm::Value *CodeGenFunction::EmitObjCStringLiteral(const ObjCStringLiteral *E)
{
  llvm::Constant *C = 
      CGM.getObjCRuntime().GenerateConstantString(E->getString());
  // FIXME: This bitcast should just be made an invariant on the Runtime.
  return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType()));
}

/// Emit a selector.
llvm::Value *CodeGenFunction::EmitObjCSelectorExpr(const ObjCSelectorExpr *E) {
  // Untyped selector.
  // Note that this implementation allows for non-constant strings to be passed
  // as arguments to @selector().  Currently, the only thing preventing this
  // behaviour is the type checking in the front end.
  return CGM.getObjCRuntime().GetSelector(Builder, E->getSelector());
}

llvm::Value *CodeGenFunction::EmitObjCProtocolExpr(const ObjCProtocolExpr *E) {
  // FIXME: This should pass the Decl not the name.
  return CGM.getObjCRuntime().GenerateProtocolRef(Builder, E->getProtocol());
}

/// \brief Adjust the type of the result of an Objective-C message send 
/// expression when the method has a related result type.
static RValue AdjustRelatedResultType(CodeGenFunction &CGF,
                                      const Expr *E,
                                      const ObjCMethodDecl *Method,
                                      RValue Result) {
  if (!Method)
    return Result;
  if (!Method->hasRelatedResultType() ||
      CGF.getContext().hasSameType(E->getType(), Method->getResultType()) ||
      !Result.isScalar())
    return Result;
  
  // We have applied a related result type. Cast the rvalue appropriately.
  return RValue::get(CGF.Builder.CreateBitCast(Result.getScalarVal(),
                                               CGF.ConvertType(E->getType())));
}

RValue CodeGenFunction::EmitObjCMessageExpr(const ObjCMessageExpr *E,
                                            ReturnValueSlot Return) {
  // Only the lookup mechanism and first two arguments of the method
  // implementation vary between runtimes.  We can get the receiver and
  // arguments in generic code.

  CGObjCRuntime &Runtime = CGM.getObjCRuntime();
  bool isSuperMessage = false;
  bool isClassMessage = false;
  ObjCInterfaceDecl *OID = 0;
  // Find the receiver
  QualType ReceiverType;
  llvm::Value *Receiver = 0;
  switch (E->getReceiverKind()) {
  case ObjCMessageExpr::Instance:
    Receiver = EmitScalarExpr(E->getInstanceReceiver());
    ReceiverType = E->getInstanceReceiver()->getType();
    break;

  case ObjCMessageExpr::Class: {
    ReceiverType = E->getClassReceiver();
    const ObjCObjectType *ObjTy = ReceiverType->getAs<ObjCObjectType>();
    assert(ObjTy && "Invalid Objective-C class message send");
    OID = ObjTy->getInterface();
    assert(OID && "Invalid Objective-C class message send");
    Receiver = Runtime.GetClass(Builder, OID);
    isClassMessage = true;
    break;
  }

  case ObjCMessageExpr::SuperInstance:
    ReceiverType = E->getSuperType();
    Receiver = LoadObjCSelf();
    isSuperMessage = true;
    break;

  case ObjCMessageExpr::SuperClass:
    ReceiverType = E->getSuperType();
    Receiver = LoadObjCSelf();
    isSuperMessage = true;
    isClassMessage = true;
    break;
  }

  CallArgList Args;
  EmitCallArgs(Args, E->getMethodDecl(), E->arg_begin(), E->arg_end());

  QualType ResultType =
    E->getMethodDecl() ? E->getMethodDecl()->getResultType() : E->getType();

  RValue result;
  if (isSuperMessage) {
    // super is only valid in an Objective-C method
    const ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(CurFuncDecl);