C++ CanType类代码示例

static DynamicCastFeasibility
classifyDynamicCastFromProtocol(ModuleDecl *M, CanType source, CanType target,
                                bool isWholeModuleOpts) {
  assert(source.isExistentialType() &&
         "source should be an existential type");

  if (source == target)
    return DynamicCastFeasibility::WillSucceed;

  // Casts from class existential into a non-class can never succeed.
  if (source->isClassExistentialType() &&
      !target.isAnyExistentialType() &&
      !target.getClassOrBoundGenericClass() &&
      !isa<ArchetypeType>(target) &&
      !mayBridgeToObjectiveC(M, target)) {
    assert((target.getEnumOrBoundGenericEnum() ||
            target.getStructOrBoundGenericStruct() ||
            isa<TupleType>(target) ||
            isa<SILFunctionType>(target) ||
            isa<FunctionType>(target) ||
            isa<MetatypeType>(target)) &&
           "Target should be an enum, struct, tuple, metatype or function type");
    return DynamicCastFeasibility::WillFail;
  }

  // TODO: maybe prove that certain conformances are impossible?

  return DynamicCastFeasibility::MaySucceed;
}

/// Build an interface type substitution map for the given generic signature
/// from a type substitution function and conformance lookup function.
SubstitutionMap SubstitutionMap::get(GenericSignature *genericSig,
                                     TypeSubstitutionFn subs,
                                     LookupConformanceFn lookupConformance) {
  if (!genericSig) {
    return SubstitutionMap();
  }

  // Form the replacement types.
  SmallVector<Type, 4> replacementTypes;
  replacementTypes.reserve(genericSig->getGenericParams().size());
  for (auto gp : genericSig->getGenericParams()) {
    // Don't eagerly form replacements for non-canonical generic parameters.
    if (!genericSig->isCanonicalTypeInContext(gp->getCanonicalType())) {
      replacementTypes.push_back(Type());
      continue;
    }

    // Record the replacement.
    Type replacement = Type(gp).subst(subs, lookupConformance,
                                      SubstFlags::UseErrorType);
    replacementTypes.push_back(replacement);
  }

  // Form the stored conformances.
  SmallVector<ProtocolConformanceRef, 4> conformances;
  for (const auto &req : genericSig->getRequirements()) {
    if (req.getKind() != RequirementKind::Conformance) continue;

    CanType depTy = req.getFirstType()->getCanonicalType();
    auto replacement = depTy.subst(subs, lookupConformance,
                                   SubstFlags::UseErrorType);
    auto protoType = req.getSecondType()->castTo<ProtocolType>();
    auto proto = protoType->getDecl();
    auto conformance = lookupConformance(depTy, replacement, proto)
                         .getValueOr(ProtocolConformanceRef(proto));
    conformances.push_back(conformance);
  }

  return SubstitutionMap(genericSig, replacementTypes, conformances);
}

  // Collect any builtin types referenced from this type.
  void addBuiltinTypeRefs(CanType type) {
    type.visit([&](Type t) {
      if (t->is<BuiltinType>())
        BuiltinTypes.insert(CanType(t));

      // We need at least size/alignment information for types imported by
      // clang, so we'll treat them as a builtin type, essentially an
      // opaque blob.
      if (auto Nominal = t->getAnyNominal())
        if (Nominal->hasClangNode())
          BuiltinTypes.insert(CanType(t));
    });
  }

/// Perform a foreign error check by testing whether the call result is zero.
/// The call result is otherwise ignored.
static void
emitResultIsZeroErrorCheck(SILGenFunction &gen, SILLocation loc,
                           ManagedValue result, ManagedValue errorSlot,
                           bool suppressErrorCheck, bool zeroIsError) {
  // Just ignore the call result if we're suppressing the error check.
  if (suppressErrorCheck) {
    return;
  }

  SILValue resultValue =
    emitUnwrapIntegerResult(gen, loc, result.getUnmanagedValue());
  CanType resultType = resultValue->getType().getSwiftRValueType();

  if (!resultType->isBuiltinIntegerType(1)) {
    SILValue zero =
      gen.B.createIntegerLiteral(loc, resultValue->getType(), 0);

    ASTContext &ctx = gen.getASTContext();
    resultValue =
      gen.B.createBuiltinBinaryFunction(loc,
                                        "cmp_ne",
                                        resultValue->getType(),
                                        SILType::getBuiltinIntegerType(1, ctx),
                                        {resultValue, zero});
  }

  SILBasicBlock *errorBB = gen.createBasicBlock(FunctionSection::Postmatter);
  SILBasicBlock *contBB = gen.createBasicBlock();

  if (zeroIsError)
    gen.B.createCondBranch(loc, resultValue, contBB, errorBB);
  else
    gen.B.createCondBranch(loc, resultValue, errorBB, contBB);

  gen.emitForeignErrorBlock(loc, errorBB, errorSlot);

  gen.B.emitBlock(contBB);
}

FormalLinkage swift::getTypeLinkage(CanType type) {
  FormalLinkage result = FormalLinkage::Top;

  // Merge all nominal types from the structural type.
  (void) type.findIf([&](Type _type) {
    CanType type = CanType(_type);

    // For any nominal type reference, look at the type declaration.
    if (auto nominal = type->getAnyNominal()) {
      result ^= getDeclLinkage(nominal);

    // For polymorphic function types, look at the generic parameters.
    // FIXME: findIf should do this, once polymorphic function types can be
    // canonicalized and re-formed properly.
    } else if (auto polyFn = dyn_cast<PolymorphicFunctionType>(type)) {
      result ^= getGenericClauseLinkage(polyFn->getGenericParameters());
    }

    return false; // continue searching
  });

  return result;
}

/// 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);
  
  AbstractionPattern origType = AbstractionPattern::getOpaque();

  // 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);
}

bool DestructorAnalysis::isSafeType(CanType Ty) {
  // Don't visit types twice.
  auto CachedRes = Cached.find(Ty);
  if (CachedRes != Cached.end()) {
    return CachedRes->second;
  }

  // Before we recurse mark the type as safe i.e if we see it in a recursive
  // position it is safe in the absence of another fact that proves otherwise.
  // We will reset this value to the correct value once we return from the
  // recursion below.
  cacheResult(Ty, true);

  // Trivial value types.
  if (Ty->is<BuiltinIntegerType>())
    return cacheResult(Ty, true);
  if (Ty->is<BuiltinFloatType>())
    return cacheResult(Ty, true);

  // A struct is safe if
  //   * either it implements the _DestructorSafeContainer protocol and
  //     all the type parameters are safe types.
  //   * or all stored properties are safe types.
  if (auto *Struct = Ty->getStructOrBoundGenericStruct()) {

    if (implementsDestructorSafeContainerProtocol(Struct) &&
        areTypeParametersSafe(Ty))
      return cacheResult(Ty, true);

    // Check the stored properties.
    for (auto SP : Struct->getStoredProperties())
      if (!isSafeType(SP->getInterfaceType()->getCanonicalType()))
        return cacheResult(Ty, false);

    return cacheResult(Ty, true);
  }

  // A tuple type is safe if its elements are safe.
  if (auto Tuple = dyn_cast<TupleType>(Ty)) {
    for (auto &Elt : Tuple->getElements())
      if (!isSafeType(Elt.getType()->getCanonicalType()))
        return cacheResult(Ty, false);
    return cacheResult(Ty, true);
  }

  // TODO: enum types.

  return cacheResult(Ty, false);
}

CanType swift::getNSBridgedClassOfCFClass(ModuleDecl *M, CanType type) {
  if (auto classDecl = type->getClassOrBoundGenericClass()) {
    if (classDecl->getForeignClassKind() == ClassDecl::ForeignKind::CFType) {
      if (auto bridgedAttr =
            classDecl->getAttrs().getAttribute<ObjCBridgedAttr>()) {
        auto bridgedClass = bridgedAttr->getObjCClass();
        // TODO: this should handle generic classes properly.
        if (!bridgedClass->isGenericContext()) {
          return bridgedClass->getDeclaredInterfaceType()->getCanonicalType();
        }
      }
    }
  }
  return CanType();
}

  /// Add a 32-bit relative offset to a mangled typeref string
  /// in the typeref reflection section.
  void addTypeRef(Module *ModuleContext, CanType type) {
    assert(type);

    // Generic parameters should be written in terms of interface types
    // for the purposes of reflection metadata
    assert(!type->hasArchetype() && "Forgot to map typeref out of context");

    Mangle::Mangler mangler(/*DWARFMangling*/false,
                            /*usePunyCode*/ true,
                            /*OptimizeProtocolNames*/ false);
    mangler.setModuleContext(ModuleContext);
    mangler.mangleType(type, 0);
    auto mangledName = IGM.getAddrOfStringForTypeRef(mangler.finalize());
    addRelativeAddress(mangledName);
  }

CanType TypeConverter::getBridgedInputType(SILFunctionTypeRepresentation rep,
                                           AbstractionPattern pattern,
                                           CanType input) {
  if (auto tuple = dyn_cast<TupleType>(input)) {
    SmallVector<TupleTypeElt, 4> bridgedFields;
    bool changed = false;

    for (unsigned i : indices(tuple->getElements())) {
      auto &elt = tuple->getElement(i);
      Type bridged = getLoweredBridgedType(pattern.getTupleElementType(i),
                                           elt.getType(), rep,
                                           TypeConverter::ForArgument);
      if (!bridged) {
        Context.Diags.diagnose(SourceLoc(), diag::could_not_find_bridge_type,
                               elt.getType());

        llvm::report_fatal_error("unable to set up the ObjC bridge!");
      }

      CanType canBridged = bridged->getCanonicalType();
      if (canBridged != CanType(elt.getType())) {
        changed = true;
        bridgedFields.push_back(elt.getWithType(canBridged));
      } else {
        bridgedFields.push_back(elt);
      }
    }

    if (!changed)
      return input;
    return CanType(TupleType::get(bridgedFields, input->getASTContext()));
  }

  auto loweredBridgedType = getLoweredBridgedType(pattern, input, rep,
                                                  TypeConverter::ForArgument);

  if (!loweredBridgedType) {
    Context.Diags.diagnose(SourceLoc(), diag::could_not_find_bridge_type,
                           input);

    llvm::report_fatal_error("unable to set up the ObjC bridge!");
  }

  return loweredBridgedType->getCanonicalType();
}

Optional<ProtocolConformanceRef>
SubstitutionMap::forEachParent(CanType type, Fn fn) const {
  auto foundParents = parentMap.find(type.getPointer());
  if (foundParents != parentMap.end()) {
    for (auto parent : foundParents->second) {
      if (auto result = fn(parent.first, parent.second))
        return result;
    }
  }

  if (auto archetypeType = dyn_cast<ArchetypeType>(type))
    if (auto *parent = archetypeType->getParent())
      return fn(CanType(parent), archetypeType->getAssocType());

  if (auto memberType = dyn_cast<DependentMemberType>(type))
    return fn(CanType(memberType->getBase()), memberType->getAssocType());

  return None;
}

// FIXME: With some changes to their callers, all of the below functions
// could be re-worked to use emitInjectEnum().
ManagedValue
SILGenFunction::emitInjectOptional(SILLocation loc,
                                   ManagedValue v,
                                   CanType inputFormalType,
                                   CanType substFormalType,
                                   const TypeLowering &expectedTL,
                                   SGFContext ctxt) {
  // Optional's payload is currently maximally abstracted. FIXME: Eventually
  // it shouldn't be.
  auto opaque = AbstractionPattern::getOpaque();

  OptionalTypeKind substOTK;
  auto substObjectType = substFormalType.getAnyOptionalObjectType(substOTK);

  auto loweredTy = getLoweredType(opaque, substObjectType);
  if (v.getType() != loweredTy)
    v = emitTransformedValue(loc, v,
                             AbstractionPattern(inputFormalType), inputFormalType,
                             opaque, substObjectType);

  auto someDecl = getASTContext().getOptionalSomeDecl(substOTK);
  SILType optTy = getLoweredType(substFormalType);
  if (v.getType().isAddress()) {
    auto buf = getBufferForExprResult(loc, optTy.getObjectType(), ctxt);
    auto payload = B.createInitEnumDataAddr(loc, buf, someDecl,
                                            v.getType());
    // FIXME: Is it correct to use IsTake here even if v doesn't have a cleanup?
    B.createCopyAddr(loc, v.forward(*this), payload,
                     IsTake, IsInitialization);
    B.createInjectEnumAddr(loc, buf, someDecl);
    v = manageBufferForExprResult(buf, expectedTL, ctxt);
  } else {
    auto some = B.createEnum(loc, v.getValue(), someDecl, optTy);
    v = ManagedValue(some, v.getCleanup());
  }

  return v;
}

  /// Add a 32-bit relative offset to a mangled typeref string
  /// in the typeref reflection section.
  void addTypeRef(ModuleDecl *ModuleContext, CanType type,
                  CanGenericSignature Context = {}) {
    assert(type);

    // Generic parameters should be written in terms of interface types
    // for the purposes of reflection metadata
    assert(!type->hasArchetype() && "Forgot to map typeref out of context");

    // TODO: As a compatibility hack, mangle single-field boxes with the legacy
    // mangling in reflection metadata.
    bool isSingleFieldOfBox = false;
    auto boxTy = dyn_cast<SILBoxType>(type);
    if (boxTy && boxTy->getLayout()->getFields().size() == 1) {
      GenericContextScope scope(IGM, Context);
      type = boxTy->getFieldLoweredType(IGM.getSILModule(), 0);
      isSingleFieldOfBox = true;
    }
    IRGenMangler mangler;
    std::string MangledStr = mangler.mangleTypeForReflection(type,
                                            ModuleContext, isSingleFieldOfBox);
    auto mangledName = IGM.getAddrOfStringForTypeRef(MangledStr);
    addRelativeAddress(mangledName);
  }

  // Collect any builtin types referenced from this type.
  void addBuiltinTypeRefs(CanType type) {
    type.visit([&](Type t) {
      if (t->is<BuiltinType>())
        IGM.BuiltinTypes.insert(CanType(t));

      // We need size/alignment information for imported value types,
      // so emit builtin descriptors for them.
      //
      // In effect they're treated like an opaque blob, which is OK
      // for now, at least until we want to import C++ types or
      // something like that.
      //
      // Classes and protocols go down a different path.
      if (auto Nominal = t->getAnyNominal())
        if (Nominal->hasClangNode()) {
          if (auto CD = dyn_cast<ClassDecl>(Nominal))
            IGM.ImportedClasses.insert(CD);
          else if (auto PD = dyn_cast<ProtocolDecl>(Nominal))
            IGM.ImportedProtocols.insert(PD);
          else
            IGM.BuiltinTypes.insert(CanType(t));
        }
    });
  }

/// Is metadata for the given type kind a "leaf", or does it possibly
/// store any other type metadata that we can statically extract?
///
/// It's okay to conservatively answer "no".  It's more important for this
/// to be quick than for it to be accurate; don't recurse.
static bool isLeafTypeMetadata(CanType type) {
  switch (type->getKind()) {
#define SUGARED_TYPE(ID, SUPER) \
  case TypeKind::ID:
#define UNCHECKED_TYPE(ID, SUPER) \
  case TypeKind::ID:
#define TYPE(ID, SUPER)
#include "swift/AST/TypeNodes.def"
    llvm_unreachable("kind is invalid for a canonical type");

#define ARTIFICIAL_TYPE(ID, SUPER) \
  case TypeKind::ID:
#define TYPE(ID, SUPER)
#include "swift/AST/TypeNodes.def"
  case TypeKind::LValue:
  case TypeKind::InOut:
  case TypeKind::DynamicSelf:
    llvm_unreachable("these types do not have metadata");

  // All the builtin types are leaves.
#define BUILTIN_TYPE(ID, SUPER) \
  case TypeKind::ID:
#define TYPE(ID, SUPER)
#include "swift/AST/TypeNodes.def"
  case TypeKind::Module:
    return true;

  // Type parameters are statically opaque.
  case TypeKind::Archetype:
  case TypeKind::GenericTypeParam:
  case TypeKind::DependentMember:
    return true;

  // Only the empty tuple is a leaf.
  case TypeKind::Tuple:
    return cast<TupleType>(type)->getNumElements() == 0;

  // Nominal types might have parents.
  case TypeKind::Class:
  case TypeKind::Enum:
  case TypeKind::Protocol:
  case TypeKind::Struct:
    return !cast<NominalType>(type)->getParent();

  // Bound generic types have type arguments.
  case TypeKind::BoundGenericClass:
  case TypeKind::BoundGenericEnum:
  case TypeKind::BoundGenericStruct:
    return false;

  // Functions have component types.
  case TypeKind::Function:
  case TypeKind::PolymorphicFunction:
  case TypeKind::GenericFunction:  // included for future-proofing
    return false;

  // Protocol compositions have component types.
  case TypeKind::ProtocolComposition:
    return false;

  // Metatypes have instance types.
  case TypeKind::Metatype:
  case TypeKind::ExistentialMetatype:
    return false;
  }
  llvm_unreachable("bad type kind");
}