Пример #1
0
LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,
                                               const ObjCInterfaceDecl *OID,
                                               llvm::Value *BaseValue,
                                               const ObjCIvarDecl *Ivar,
                                               unsigned CVRQualifiers,
                                               llvm::Value *Offset) {
  // Compute (type*) ( (char *) BaseValue + Offset)
  QualType IvarTy = Ivar->getType();
  llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
  llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, CGF.Int8PtrTy);
  V = CGF.Builder.CreateInBoundsGEP(V, Offset, "add.ptr");

  if (!Ivar->isBitField()) {
    V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
    LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
    LV.getQuals().addCVRQualifiers(CVRQualifiers);
    return LV;
  }

  // We need to compute an access strategy for this bit-field. We are given the
  // offset to the first byte in the bit-field, the sub-byte offset is taken
  // from the original layout. We reuse the normal bit-field access strategy by
  // treating this as an access to a struct where the bit-field is in byte 0,
  // and adjust the containing type size as appropriate.
  //
  // FIXME: Note that currently we make a very conservative estimate of the
  // alignment of the bit-field, because (a) it is not clear what guarantees the
  // runtime makes us, and (b) we don't have a way to specify that the struct is
  // at an alignment plus offset.
  //
  // Note, there is a subtle invariant here: we can only call this routine on
  // non-synthesized ivars but we may be called for synthesized ivars.  However,
  // a synthesized ivar can never be a bit-field, so this is safe.
  uint64_t FieldBitOffset = LookupFieldBitOffset(CGF.CGM, OID, nullptr, Ivar);
  uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
  uint64_t AlignmentBits = CGF.CGM.getTarget().getCharAlign();
  uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
  CharUnits StorageSize =
    CGF.CGM.getContext().toCharUnitsFromBits(
      llvm::RoundUpToAlignment(BitOffset + BitFieldSize, AlignmentBits));
  CharUnits Alignment = CGF.CGM.getContext().toCharUnitsFromBits(AlignmentBits);

  // Allocate a new CGBitFieldInfo object to describe this access.
  //
  // FIXME: This is incredibly wasteful, these should be uniqued or part of some
  // layout object. However, this is blocked on other cleanups to the
  // Objective-C code, so for now we just live with allocating a bunch of these
  // objects.
  CGBitFieldInfo *Info = new (CGF.CGM.getContext()) CGBitFieldInfo(
    CGBitFieldInfo::MakeInfo(CGF.CGM.getTypes(), Ivar, BitOffset, BitFieldSize,
                             CGF.CGM.getContext().toBits(StorageSize),
                             CharUnits::fromQuantity(0)));

  V = CGF.Builder.CreateBitCast(V,
                                llvm::Type::getIntNPtrTy(CGF.getLLVMContext(),
                                                         Info->StorageSize));
  return LValue::MakeBitfield(V, *Info,
                              IvarTy.withCVRQualifiers(CVRQualifiers),
                              Alignment);
}
CodeGen::RValue
CGObjCJit::EmitMessageSend(CodeGen::CodeGenFunction &CGF,
                           ReturnValueSlot Return,
                           QualType ResultType,
                           Selector Sel,
                           llvm::Value *Arg0,
                           llvm::Value *Arg0Class,
                           const CallArgList &CallArgs,
                           const ObjCMethodDecl *Method) {

  llvm::Value *Arg1 = GetSelector(CGF, Sel);

  CallArgList ActualArgs;
  ActualArgs.add(RValue::get(Arg0), CGF.getContext().getObjCIdType());
  ActualArgs.add(RValue::get(Arg1), CGF.getContext().getObjCSelType());
  ActualArgs.addFrom(CallArgs);

  if (Method)
    assert(CGM.getContext().getCanonicalType(Method->getResultType()) ==
           CGM.getContext().getCanonicalType(ResultType) &&
           "Result type mismatch!");

  // Perform the following:
  //   imp = class_getMethodImplementation( Arg0Class, Arg1 );
  //   (*imp)( Arg0, Arg1, CallArgs );
  llvm::CallInst *getImp;

  // Unfortunately, using the GNU runtime version of
  // class_getMethodImplementation and then calling the resulting
  // IMP doesn't work unless objc_msg_lookup was already
  // called first. TODO: avoid doing this every time
  //
  if (fn_objc_msg_lookup.isValid()) {
    getImp = CGF.Builder.CreateCall2(fn_objc_msg_lookup,
                                     Arg0,
                                     Arg1);
  } else { // use the universal way
    getImp = CGF.Builder.CreateCall2(fn_class_getMethodImplementation,
                                     Arg0Class,
                                     Arg1);
  }

  MessageSendInfo MSI = getMessageSendInfo(Method, ResultType, ActualArgs);
  llvm::Value *theImp = CGF.Builder.CreateBitCast(getImp, MSI.MessengerType);
  return CGF.EmitCall(MSI.CallInfo, theImp, Return, ActualArgs);
}