C++ TypeLowering::isLoadable方法代码示例

/// Return a value for an optional ".Some(x)" of the specified type. This only
/// works for loadable enum types.
ManagedValue SILGenFunction::
getOptionalSomeValue(SILLocation loc, ManagedValue value,
                     const TypeLowering &optTL) {
  assert(optTL.isLoadable() && "Address-only optionals cannot use this");
  SILType optType = optTL.getLoweredType();
  CanType formalOptType = optType.getSwiftRValueType();

  OptionalTypeKind OTK;
  auto formalObjectType = formalOptType->getAnyOptionalObjectType(OTK)
    ->getCanonicalType();
  assert(OTK != OTK_None);
  auto someDecl = getASTContext().getOptionalSomeDecl(OTK);
  
  auto archetype = formalOptType->getNominalOrBoundGenericNominal()
                        ->getGenericParams()->getPrimaryArchetypes()[0];
  AbstractionPattern origType(archetype);

  
  // Reabstract input value to the type expected by the enum.
  value = emitSubstToOrigValue(loc, value, origType, formalObjectType);

  SILValue result =
    B.createEnum(loc, value.forward(*this), someDecl,
                 optTL.getLoweredType());
  return emitManagedRValueWithCleanup(result, optTL);
}

/// Return a value for an optional ".None" of the specified type. This only
/// works for loadable enum types.
SILValue SILGenFunction::getOptionalNoneValue(SILLocation loc,
                                              const TypeLowering &optTL) {
  assert(optTL.isLoadable() && "Address-only optionals cannot use this");
  assert(optTL.getLoweredType().getAnyOptionalObjectType());

  return B.createEnum(loc, SILValue(), getASTContext().getOptionalNoneDecl(),
                      optTL.getLoweredType());
}

/// Return a value for an optional ".Some(x)" of the specified type. This only
/// works for loadable enum types.
ManagedValue SILGenFunction::
getOptionalSomeValue(SILLocation loc, ManagedValue value,
                     const TypeLowering &optTL) {
  assert(optTL.isLoadable() && "Address-only optionals cannot use this");
  SILType optType = optTL.getLoweredType();
  CanType formalOptType = optType.getSwiftRValueType();

  auto formalObjectType = formalOptType.getAnyOptionalObjectType();
  assert(formalObjectType);
  auto someDecl = getASTContext().getOptionalSomeDecl();
  
  SILValue result =
    B.createEnum(loc, value.forward(*this), someDecl, optTL.getLoweredType());
  return emitManagedRValueWithCleanup(result, optTL);
}

ManagedValue SILGenFunction::emitUncheckedGetOptionalValueFrom(SILLocation loc,
                                                    ManagedValue addrOrValue,
                                                    const TypeLowering &optTL,
                                                    SGFContext C) {
  OptionalTypeKind OTK;
  SILType origPayloadTy =
    addrOrValue.getType().getAnyOptionalObjectType(SGM.M, OTK);

  auto formalOptionalTy = addrOrValue.getType().getSwiftRValueType();
  auto formalPayloadTy = formalOptionalTy
    ->getAnyOptionalObjectType()
    ->getCanonicalType();
  
  auto someDecl = getASTContext().getOptionalSomeDecl(OTK);
 
  ManagedValue payload;

  // Take the payload from the optional.  Cheat a bit in the +0
  // case—UncheckedTakeEnumData will never actually invalidate an Optional enum
  // value.
  SILValue payloadVal;
  if (!addrOrValue.getType().isAddress()) {
    payloadVal = B.createUncheckedEnumData(loc, addrOrValue.forward(*this),
                                           someDecl);
  } else {
    payloadVal =
      B.createUncheckedTakeEnumDataAddr(loc, addrOrValue.forward(*this),
                                        someDecl, origPayloadTy);
  
    if (optTL.isLoadable())
      payloadVal = B.createLoad(loc, payloadVal);
  }

  // Produce a correctly managed value.
  if (addrOrValue.hasCleanup())
    payload = emitManagedRValueWithCleanup(payloadVal);
  else
    payload = ManagedValue::forUnmanaged(payloadVal);
  
  // Reabstract it to the substituted form, if necessary.
  return emitOrigToSubstValue(loc, payload, AbstractionPattern::getOpaque(),
                              formalPayloadTy, C);
}

ManagedValue SILGenFunction::emitUncheckedGetOptionalValueFrom(SILLocation loc,
                                                    ManagedValue addrOrValue,
                                                    const TypeLowering &optTL,
                                                    SGFContext C) {
  SILType origPayloadTy =
    addrOrValue.getType().getAnyOptionalObjectType();

  auto someDecl = getASTContext().getOptionalSomeDecl();
 
  ManagedValue payload;

  // Take the payload from the optional.  Cheat a bit in the +0
  // case--UncheckedTakeEnumData will never actually invalidate an Optional enum
  // value.
  SILValue payloadVal;
  if (!addrOrValue.getType().isAddress()) {
    payloadVal = B.createUncheckedEnumData(loc, addrOrValue.forward(*this),
                                           someDecl);
  } else {
    payloadVal =
      B.createUncheckedTakeEnumDataAddr(loc, addrOrValue.forward(*this),
                                        someDecl, origPayloadTy);
  
    if (optTL.isLoadable())
      payloadVal =
          optTL.emitLoad(B, loc, payloadVal, LoadOwnershipQualifier::Take);
  }

  // Produce a correctly managed value.
  if (addrOrValue.hasCleanup())
    payload = emitManagedRValueWithCleanup(payloadVal);
  else
    payload = ManagedValue::forUnmanaged(payloadVal);
  
  return payload;
}

//.........这里部分代码省略.........

      // If we did not get an NSError, just directly emit the existential.
      // Since this is a recursive call, make sure we don't end up in this
      // path again.
      B.emitBlock(isNotPresentBB);
      {
        FullExpr presentScope(Cleanups, CleanupLocation::get(loc));
        concreteValue = emitManagedRValueWithCleanup(concreteValue.getValue());
        branchArg = emitExistentialErasure(loc, concreteFormalType, concreteTL,
                                           existentialTL, conformances,
                                           SGFContext(),
                                           [&](SGFContext C) {
                                             return concreteValue;
                                           },
                                           /*allowEmbeddedNSError=*/false)
                      .forward(*this);
      }
      B.createBranch(loc, contBB, branchArg);

      // Continue.
      B.emitBlock(contBB);

      SILValue existentialResult = contBB->createPHIArgument(
          existentialTL.getLoweredType(), ValueOwnershipKind::Owned);
      return emitManagedRValueWithCleanup(existentialResult, existentialTL);
    }
  }

  switch (existentialTL.getLoweredType().getObjectType()
            .getPreferredExistentialRepresentation(SGM.M, concreteFormalType)) {
  case ExistentialRepresentation::None:
    llvm_unreachable("not an existential type");
  case ExistentialRepresentation::Metatype: {
    assert(existentialTL.isLoadable());

    SILValue metatype = F(SGFContext()).getUnmanagedValue();
    assert(metatype->getType().castTo<AnyMetatypeType>()->getRepresentation()
             == MetatypeRepresentation::Thick);

    auto upcast =
      B.createInitExistentialMetatype(loc, metatype,
                                      existentialTL.getLoweredType(),
                                      conformances);
    return ManagedValue::forUnmanaged(upcast);
  }
  case ExistentialRepresentation::Class: {
    assert(existentialTL.isLoadable());

    ManagedValue sub = F(SGFContext());
    SILValue v = B.createInitExistentialRef(loc,
                                            existentialTL.getLoweredType(),
                                            concreteFormalType,
                                            sub.getValue(),
                                            conformances);
    return ManagedValue(v, sub.getCleanup());
  }
  case ExistentialRepresentation::Boxed: {
    // Allocate the existential.
    auto *existential = B.createAllocExistentialBox(loc,
                                           existentialTL.getLoweredType(),
                                           concreteFormalType,
                                           conformances);
    auto *valueAddr = B.createProjectExistentialBox(loc,
                                           concreteTL.getLoweredType(),
                                           existential);
    // Initialize the concrete value in-place.

//.........这里部分代码省略.........
                // as 'AnyObject' for layering reasons.
                return ManagedValue(B.createUncheckedRefCast(
                                      loc,
                                      nsErrorValue.getValue(),
                                      getLoweredType(nsErrorType)),
                                    nsErrorValue.getCleanup());

              }).forward(*this);
        }
        B.createBranch(loc, contBB, branchArg);

        // If we did not get an NSError, just directly emit the existential
        // (recursively).
        B.emitBlock(isNotPresentBB);
        branchArg = emitExistentialErasure(loc, concreteFormalType, concreteTL,
                                           existentialTL, conformances,
                                           SGFContext(), F,
                                           /*allowEmbeddedNSError=*/false)
                      .forward(*this);
        B.createBranch(loc, contBB, branchArg);

        // Continue.
        B.emitBlock(contBB);
        return emitManagedRValueWithCleanup(existentialResult, existentialTL);
      }
    }
  }

  switch (existentialTL.getLoweredType().getObjectType()
            .getPreferredExistentialRepresentation(SGM.M, concreteFormalType)) {
  case ExistentialRepresentation::None:
    llvm_unreachable("not an existential type");
  case ExistentialRepresentation::Metatype: {
    assert(existentialTL.isLoadable());

    SILValue metatype = F(SGFContext()).getUnmanagedValue();
    assert(metatype->getType().castTo<AnyMetatypeType>()->getRepresentation()
             == MetatypeRepresentation::Thick);

    auto upcast =
      B.createInitExistentialMetatype(loc, metatype,
                                      existentialTL.getLoweredType(),
                                      conformances);
    return ManagedValue::forUnmanaged(upcast);
  }
  case ExistentialRepresentation::Class: {
    assert(existentialTL.isLoadable());

    ManagedValue sub = F(SGFContext());
    SILValue v = B.createInitExistentialRef(loc,
                                            existentialTL.getLoweredType(),
                                            concreteFormalType,
                                            sub.getValue(),
                                            conformances);
    return ManagedValue(v, sub.getCleanup());
  }
  case ExistentialRepresentation::Boxed: {
    // Allocate the existential.
    auto *existential = B.createAllocExistentialBox(loc,
                                           existentialTL.getLoweredType(),
                                           concreteFormalType,
                                           conformances);
    auto *valueAddr = B.createProjectExistentialBox(loc,
                                           concreteTL.getLoweredType(),
                                           existential);
    // Initialize the concrete value in-place.

ManagedValue SILGenFunction::emitExistentialErasure(
                            SILLocation loc,
                            CanType concreteFormalType,
                            const TypeLowering &concreteTL,
                            const TypeLowering &existentialTL,
                            const ArrayRef<ProtocolConformance *> &conformances,
                            SGFContext C,
                            llvm::function_ref<ManagedValue (SGFContext)> F) {
  // Mark the needed conformances as used.
  for (auto *conformance : conformances)
    SGM.useConformance(conformance);

  switch (existentialTL.getLoweredType().getObjectType()
            .getPreferredExistentialRepresentation(SGM.M, concreteFormalType)) {
  case ExistentialRepresentation::None:
    llvm_unreachable("not an existential type");
  case ExistentialRepresentation::Metatype: {
    assert(existentialTL.isLoadable());

    SILValue metatype = F(SGFContext()).getUnmanagedValue();
    assert(metatype.getType().castTo<AnyMetatypeType>()->getRepresentation()
             == MetatypeRepresentation::Thick);

    auto upcast =
      B.createInitExistentialMetatype(loc, metatype,
                                      existentialTL.getLoweredType(),
                                      conformances);
    return ManagedValue::forUnmanaged(upcast);
  }
  case ExistentialRepresentation::Class: {
    assert(existentialTL.isLoadable());

    ManagedValue sub = F(SGFContext());
    SILValue v = B.createInitExistentialRef(loc,
                                            existentialTL.getLoweredType(),
                                            concreteFormalType,
                                            sub.getValue(),
                                            conformances);
    return ManagedValue(v, sub.getCleanup());
  }
  case ExistentialRepresentation::Boxed: {
    // Allocate the existential.
    auto box = B.createAllocExistentialBox(loc,
                                           existentialTL.getLoweredType(),
                                           concreteFormalType,
                                           concreteTL.getLoweredType(),
                                           conformances);
    auto existential = box->getExistentialResult();
    auto valueAddr = box->getValueAddressResult();

    // Initialize the concrete value in-place.
    InitializationPtr init(
        new ExistentialInitialization(existential, valueAddr, concreteFormalType,
                                      ExistentialRepresentation::Boxed,
                                      *this));
    ManagedValue mv = F(SGFContext(init.get()));
    if (!mv.isInContext()) {
      mv.forwardInto(*this, loc, init->getAddress());
      init->finishInitialization(*this);
    }
    
    return emitManagedRValueWithCleanup(existential);
  }
  case ExistentialRepresentation::Opaque: {
    // Allocate the existential.
    SILValue existential =
      getBufferForExprResult(loc, existentialTL.getLoweredType(), C);

    // Allocate the concrete value inside the container.
    SILValue valueAddr = B.createInitExistentialAddr(
                            loc, existential,
                            concreteFormalType,
                            concreteTL.getLoweredType(),
                            conformances);
    // Initialize the concrete value in-place.
    InitializationPtr init(
        new ExistentialInitialization(existential, valueAddr, concreteFormalType,
                                      ExistentialRepresentation::Opaque,
                                      *this));
    ManagedValue mv = F(SGFContext(init.get()));
    if (!mv.isInContext()) {
      mv.forwardInto(*this, loc, init->getAddress());
      init->finishInitialization(*this);
    }

    return manageBufferForExprResult(existential, existentialTL, C);
  }
  }
}