static bool verifySILSelfParameterType(SILDeclRef DeclRef,
SILFunction *F, CanSILFunctionType FTy) {
SILModule &M = F->getModule();
SILParameterInfo PInfo = FTy->getSelfParameter();
CanType CTy = PInfo.getType();
SILType Ty = SILType::getPrimitiveObjectType(CTy);
// We do not care about trivial parameters (for now). There seem to be
// cases where we lower them as unowned.
//
// *NOTE* We do not run this check when we have a generic type since
// *generic types do not have type lowering and are always treated as
// *non-trivial since we do not know the type.
if (CTy->hasArchetype() || CTy->hasTypeParameter() ||
M.getTypeLowering(Ty).isTrivial())
return true;
// If this function is a constructor or destructor, bail. These have @owned
// parameters.
if (DeclRef.isConstructor() || DeclRef.isDestructor())
return true;
// Otherwise, if this function type has a guaranteed self parameter type,
// make sure that we have a +0 self param.
return !FTy->getExtInfo().hasGuaranteedSelfParam() ||
PInfo.isGuaranteed() || PInfo.isIndirectMutating();
}
static bool
mustBridgeToSwiftValueBox(Module *M, CanType T) {
// If the target type is either an unknown dynamic type, or statically
// known to bridge, the cast may succeed.
if (T->hasArchetype())
return false;
if (T->isAnyExistentialType())
return false;
// getBridgedToObjC() might return a null-type for bridged foundation types
// during compiling the standard library. Exclude this case here.
if (auto N = T->getAnyNominal())
if (M->getASTContext().isStandardLibraryTypeBridgedInFoundation(N))
return false;
auto bridgeTy = M->getASTContext().getBridgedToObjC(M, T, nullptr);
if (!bridgeTy.hasValue())
return false;
if (bridgeTy->isNull())
return true;
return false;
}
void OutliningMetadataCollector::collectFormalTypeMetadata(CanType type) {
// If the type has no archetypes, we can emit it from scratch in the callee.
assert(type->hasArchetype());
auto key = LocalTypeDataKey(type, LocalTypeDataKind::forFormalTypeMetadata());
if (Values.count(key)) return;
auto metadata = IGF.emitTypeMetadataRef(type);
Values.insert({key, metadata});
}
/// 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);
}
static bool
mayBridgeToObjectiveC(Module *M, CanType T) {
// If the target type is either an unknown dynamic type, or statically
// known to bridge, the cast may succeed.
// TODO: We could be more precise with the bridged-to type.
if (T->hasArchetype())
return true;
if (T->isAnyExistentialType())
return true;
if (M->getASTContext().getBridgedToObjC(M, T, nullptr))
return true;
return false;
}
static bool
mustBridgeToSwiftValueBox(ModuleDecl *M, CanType T) {
// If the target type is either an unknown dynamic type, or statically
// known to bridge, the cast may succeed.
if (T->hasArchetype())
return false;
if (T->isAnyExistentialType())
return false;
// getBridgedToObjC() might return a null-type for some types
// whose bridging implementation is allowed to live elsewhere. Exclude this
// case here.
if (auto N = T->getAnyNominal())
if (M->getASTContext().isTypeBridgedInExternalModule(N))
return false;
return !M->getASTContext().getBridgedToObjC(M, T);
}
/// 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);
}
void LocalTypeDataCache::
addAbstractForFulfillments(IRGenFunction &IGF, FulfillmentMap &&fulfillments,
llvm::function_ref<AbstractSource()> createSource) {
// Add the source lazily.
Optional<unsigned> sourceIndex;
auto getSourceIndex = [&]() -> unsigned {
if (!sourceIndex) {
AbstractSources.emplace_back(createSource());
sourceIndex = AbstractSources.size() - 1;
}
return *sourceIndex;
};
for (auto &fulfillment : fulfillments) {
CanType type = CanType(fulfillment.first.first);
LocalTypeDataKind localDataKind;
// For now, ignore witness-table fulfillments when they're not for
// archetypes.
if (ProtocolDecl *protocol = fulfillment.first.second) {
if (auto archetype = dyn_cast<ArchetypeType>(type)) {
auto conformsTo = archetype->getConformsTo();
auto it = std::find(conformsTo.begin(), conformsTo.end(), protocol);
if (it == conformsTo.end()) continue;
localDataKind = LocalTypeDataKind::forAbstractProtocolWitnessTable(*it);
} else {
continue;
}
} else {
// Ignore type metadata fulfillments for non-dependent types that
// we can produce very cheaply. We don't want to end up emitting
// the type metadata for Int by chasing through N layers of metadata
// just because that path happens to be in the cache.
if (!type->hasArchetype() &&
isTypeMetadataAccessTrivial(IGF.IGM, type)) {
continue;
}
localDataKind = LocalTypeDataKind::forTypeMetadata();
}
// Find the chain for the key.
auto key = getKey(type, localDataKind);
auto &chain = Map[key];
// Check whether there's already an entry that's at least as good as the
// fulfillment.
Optional<unsigned> fulfillmentCost;
auto getFulfillmentCost = [&]() -> unsigned {
if (!fulfillmentCost)
fulfillmentCost = fulfillment.second.Path.cost();
return *fulfillmentCost;
};
bool isConditional = IGF.isConditionalDominancePoint();
bool foundBetter = false;
for (CacheEntry *cur = chain.Root, *last = nullptr; cur;
last = cur, cur = cur->getNext()) {
// Ensure the entry is acceptable.
if (!IGF.isActiveDominancePointDominatedBy(cur->DefinitionPoint))
continue;
// Ensure that the entry isn't better than the fulfillment.
auto curCost = cur->cost();
if (curCost == 0 || curCost <= getFulfillmentCost()) {
foundBetter = true;
break;
}
// If the entry is defined at the current point, (1) we know there
// won't be a better entry and (2) we should remove it.
if (cur->DefinitionPoint == IGF.getActiveDominancePoint() &&
!isConditional) {
// Splice it out of the chain.
assert(!cur->isConditional());
chain.eraseEntry(last, cur);
break;
}
}
if (foundBetter) continue;
// Okay, make a new entry.
// Register with the conditional dominance scope if necessary.
if (isConditional) {
IGF.registerConditionalLocalTypeDataKey(key);
}
// Allocate the new entry.
auto newEntry = new AbstractCacheEntry(IGF.getActiveDominancePoint(),
isConditional,
getSourceIndex(),
std::move(fulfillment.second.Path));
// Add it to the front of the chain.
chain.push_front(newEntry);
}
}
/// Try to classify the dynamic-cast relationship between two types.
DynamicCastFeasibility
swift::classifyDynamicCast(ModuleDecl *M,
CanType source,
CanType target,
bool isSourceTypeExact,
bool isWholeModuleOpts) {
if (source == target) return DynamicCastFeasibility::WillSucceed;
auto sourceObject = source.getOptionalObjectType();
auto targetObject = target.getOptionalObjectType();
// A common level of optionality doesn't affect the feasibility,
// except that we can't fold things to failure because nil inhabits
// both types.
if (sourceObject && targetObject) {
return atWorst(classifyDynamicCast(M, sourceObject, targetObject),
DynamicCastFeasibility::MaySucceed);
// Casting to a more optional type follows the same rule unless we
// know that the source cannot dynamically be an optional value,
// in which case we'll always just cast and inject into an optional.
} else if (targetObject) {
auto result = classifyDynamicCast(M, source, targetObject,
/* isSourceTypeExact */ false,
isWholeModuleOpts);
if (canDynamicallyStoreOptional(source))
result = atWorst(result, DynamicCastFeasibility::MaySucceed);
return result;
// Casting to a less-optional type can always fail.
} else if (sourceObject) {
return atBest(classifyDynamicCast(M, sourceObject, target,
/* isSourceTypeExact */ false,
isWholeModuleOpts),
DynamicCastFeasibility::MaySucceed);
}
assert(!sourceObject && !targetObject);
// Assume that casts to or from existential types or involving
// dependent types can always succeed. This is over-conservative.
if (source->hasArchetype() || source.isExistentialType() ||
target->hasArchetype() || target.isExistentialType()) {
// Check conversions from non-protocol types into protocol types.
if (!source.isExistentialType() &&
target.isExistentialType())
return classifyDynamicCastToProtocol(M, source, target,
isWholeModuleOpts);
// Check conversions from protocol types to non-protocol types.
if (source.isExistentialType() &&
!target.isExistentialType())
return classifyDynamicCastFromProtocol(M, source, target,
isWholeModuleOpts);
return DynamicCastFeasibility::MaySucceed;
}
// Casts from AnyHashable.
if (auto sourceStruct = dyn_cast<StructType>(source)) {
if (sourceStruct->getDecl() == M->getASTContext().getAnyHashableDecl()) {
if (auto hashable = getHashableExistentialType(M)) {
// Succeeds if Hashable can be cast to the target type.
return classifyDynamicCastFromProtocol(M, hashable, target,
isWholeModuleOpts);
}
}
}
// Casts to AnyHashable.
if (auto targetStruct = dyn_cast<StructType>(target)) {
if (targetStruct->getDecl() == M->getASTContext().getAnyHashableDecl()) {
// Succeeds if the source type can be dynamically cast to Hashable.
// Hashable is not actually a legal existential type right now, but
// the check doesn't care about that.
if (auto hashable = getHashableExistentialType(M)) {
return classifyDynamicCastToProtocol(M, source, hashable,
isWholeModuleOpts);
}
}
}
// Metatype casts.
if (auto sourceMetatype = dyn_cast<AnyMetatypeType>(source)) {
auto targetMetatype = dyn_cast<AnyMetatypeType>(target);
if (!targetMetatype) return DynamicCastFeasibility::WillFail;
source = sourceMetatype.getInstanceType();
target = targetMetatype.getInstanceType();
if (source == target &&
targetMetatype.isAnyExistentialType() ==
sourceMetatype.isAnyExistentialType())
return DynamicCastFeasibility::WillSucceed;
// If the source and target are the same existential type, but the source is
// P.Protocol and the dest is P.Type, then we need to consider whether the
// protocol is self-conforming.
// The only cases where a protocol self-conforms are objc protocols, but
// we're going to expect P.Type to hold a class object. And this case
// doesn't matter since for a self-conforming protocol type there can't be
// any type-level methods.
// Thus we consider this kind of cast to always fail. The only exception
// from this rule is when the target is Any.Type, because *.Protocol
// can always be casted to Any.Type.
if (source->isAnyExistentialType() && isa<MetatypeType>(sourceMetatype) &&
isa<ExistentialMetatypeType>(targetMetatype)) {
return target->isAny() ? DynamicCastFeasibility::WillSucceed
: DynamicCastFeasibility::WillFail;
}
if (targetMetatype.isAnyExistentialType() &&
(isa<ProtocolType>(target) || isa<ProtocolCompositionType>(target))) {
auto Feasibility =
classifyDynamicCastToProtocol(M, source, target, isWholeModuleOpts);
// Cast from existential metatype to existential metatype may still
// succeed, even if we cannot prove anything statically.
if (Feasibility != DynamicCastFeasibility::WillFail ||
!sourceMetatype.isAnyExistentialType())
return Feasibility;
}
// If isSourceTypeExact is true, we know we are casting the result of a
// MetatypeInst instruction.
if (isSourceTypeExact) {
// If source or target are existentials, then it can be cast
// successfully only into itself.
if ((target.isAnyExistentialType() || source.isAnyExistentialType()) &&
target != source)
return DynamicCastFeasibility::WillFail;
}
// Casts from class existential metatype into a concrete non-class metatype
// can never succeed.
if (source->isClassExistentialType() &&
!target.isAnyExistentialType() &&
!target.getClassOrBoundGenericClass())
return DynamicCastFeasibility::WillFail;
// TODO: prove that some conversions to existential metatype will
// obviously succeed/fail.
// TODO: prove that some conversions from class existential metatype
// to a concrete non-class metatype will obviously fail.
// TODO: class metatype to/from AnyObject
// TODO: protocol concrete metatype to/from ObjCProtocol
if (isa<ExistentialMetatypeType>(sourceMetatype) ||
isa<ExistentialMetatypeType>(targetMetatype))
return (getAnyMetatypeDepth(source) == getAnyMetatypeDepth(target)
? DynamicCastFeasibility::MaySucceed
: DynamicCastFeasibility::WillFail);
// If both metatypes are class metatypes, check if classes can be
// cast.
if (source.getClassOrBoundGenericClass() &&
target.getClassOrBoundGenericClass())
return classifyClassHierarchyCast(source, target);
// Different structs cannot be cast to each other.
if (source.getStructOrBoundGenericStruct() &&
target.getStructOrBoundGenericStruct() &&
source != target)
return DynamicCastFeasibility::WillFail;
// Different enums cannot be cast to each other.
if (source.getEnumOrBoundGenericEnum() &&
target.getEnumOrBoundGenericEnum() &&
source != target)
return DynamicCastFeasibility::WillFail;
// If we don't know any better, assume that the cast may succeed.
return DynamicCastFeasibility::MaySucceed;
}
// Function casts.
if (auto sourceFunction = dyn_cast<FunctionType>(source)) {
if (auto targetFunction = dyn_cast<FunctionType>(target)) {
// A function cast can succeed if the function types can be identical,
// or if the target type is throwier than the original.
// A non-throwing source function can be cast to a throwing target type,
// but not vice versa.
if (sourceFunction->throws() && !targetFunction->throws())
return DynamicCastFeasibility::WillFail;
// The cast can't change the representation at runtime.
if (targetFunction->getRepresentation()
!= sourceFunction->getRepresentation())
return DynamicCastFeasibility::WillFail;
if (sourceFunction.getInput() == targetFunction.getInput()
&& sourceFunction.getResult() == targetFunction.getResult())
return DynamicCastFeasibility::WillSucceed;
auto isSubstitutable = [](CanType a, CanType b) -> bool {
// FIXME: Unnecessarily conservative; should structurally check for
// substitutability.
return a == b || a->hasArchetype() || b->hasArchetype();
};
if (isSubstitutable(sourceFunction.getInput(), targetFunction.getInput())
&& isSubstitutable(targetFunction.getInput(),
targetFunction.getResult()))
return DynamicCastFeasibility::MaySucceed;
return DynamicCastFeasibility::WillFail;
}
}
// Tuple casts.
if (auto sourceTuple = dyn_cast<TupleType>(source)) {
if (auto targetTuple = dyn_cast<TupleType>(target)) {
// # of elements must coincide.
if (sourceTuple->getNumElements() != targetTuple->getNumElements())
return DynamicCastFeasibility::WillFail;
DynamicCastFeasibility result = DynamicCastFeasibility::WillSucceed;
for (unsigned i : range(sourceTuple->getNumElements())) {
const auto &sourceElt = sourceTuple->getElement(i);
const auto &targetElt = targetTuple->getElement(i);
// If both have names and the names mismatch, the cast will fail.
if (sourceElt.hasName() && targetElt.hasName() &&
sourceElt.getName() != targetElt.getName())
return DynamicCastFeasibility::WillFail;
// Combine the result of prior elements with this element type.
result = std::max(result,
classifyDynamicCast(M,
sourceElt.getType()->getCanonicalType(),
targetElt.getType()->getCanonicalType(),
isSourceTypeExact,
isWholeModuleOpts));
// If this element failed, we're done.
if (result == DynamicCastFeasibility::WillFail)
break;
}
return result;
}
}
// Class casts.
auto sourceClass = source.getClassOrBoundGenericClass();
auto targetClass = target.getClassOrBoundGenericClass();
if (sourceClass) {
if (targetClass) {
// Imported Objective-C generics don't check the generic parameters, which
// are lost at runtime.
if (sourceClass->usesObjCGenericsModel()) {
if (sourceClass == targetClass)
return DynamicCastFeasibility::WillSucceed;
if (targetClass->usesObjCGenericsModel()) {
// If both classes are ObjC generics, the cast may succeed if the
// classes are related, irrespective of their generic parameters.
auto isDeclSuperclass = [&](ClassDecl *proposedSuper,
ClassDecl *proposedSub) -> bool {
do {
if (proposedSuper == proposedSub)
return true;
} while ((proposedSub = proposedSub->getSuperclassDecl()));
return false;
};
if (isDeclSuperclass(sourceClass, targetClass))
return DynamicCastFeasibility::MaySucceed;
if (isDeclSuperclass(targetClass, sourceClass)) {
return DynamicCastFeasibility::WillSucceed;
}
return DynamicCastFeasibility::WillFail;
}
}
// Try a hierarchy cast. If that isn't failure, we can report it.
auto hierarchyResult = classifyClassHierarchyCast(source, target);
if (hierarchyResult != DynamicCastFeasibility::WillFail)
return hierarchyResult;
// As a backup, consider whether either type is a CF class type
// with an NS bridged equivalent.
CanType bridgedSource = getNSBridgedClassOfCFClass(M, source);
CanType bridgedTarget = getNSBridgedClassOfCFClass(M, target);
// If neither type qualifies, we're done.
if (!bridgedSource && !bridgedTarget)
return DynamicCastFeasibility::WillFail;
// Otherwise, map over to the bridged types and try to answer the
// question there.
if (bridgedSource) source = bridgedSource;
if (bridgedTarget) target = bridgedTarget;
return classifyDynamicCast(M, source, target, false, isWholeModuleOpts);
}
// Casts from a class into a non-class can never succeed if the target must
// be bridged to a SwiftValueBox. You would need an AnyObject source for
// that.
if (!target.isAnyExistentialType() &&
!target.getClassOrBoundGenericClass() &&
!isa<ArchetypeType>(target) &&
mustBridgeToSwiftValueBox(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;
}
// In the Objective-C runtime, class metatypes are also class instances.
// The cast may succeed if the target type can be inhabited by a class
// metatype.
// TODO: Narrow this to the sourceClass being exactly NSObject.
if (M->getASTContext().LangOpts.EnableObjCInterop) {
if (auto targetMeta = dyn_cast<MetatypeType>(target)) {
if (isa<ArchetypeType>(targetMeta.getInstanceType())
|| targetMeta.getInstanceType()->mayHaveSuperclass())
return DynamicCastFeasibility::MaySucceed;
} else if (isa<ExistentialMetatypeType>(target)) {
return DynamicCastFeasibility::MaySucceed;
}
}
}
// If the source is not existential, an archetype, or (under the ObjC runtime)
// a class, and the destination is a metatype, there is no way the cast can
// succeed.
if (target->is<AnyMetatypeType>()) return DynamicCastFeasibility::WillFail;
// FIXME: Be more careful with bridging conversions from
// NSArray, NSDictionary and NSSet as they may fail?
// We know that a cast from Int -> class foobar will fail.
if (targetClass &&
!source.isAnyExistentialType() &&
!source.getClassOrBoundGenericClass() &&
!isa<ArchetypeType>(source) &&
mustBridgeToSwiftValueBox(M, source)) {
assert((source.getEnumOrBoundGenericEnum() ||
source.getStructOrBoundGenericStruct() ||
isa<TupleType>(source) ||
isa<SILFunctionType>(source) ||
isa<FunctionType>(source) ||
isa<MetatypeType>(source)) &&
"Source should be an enum, struct, tuple, metatype or function type");
return DynamicCastFeasibility::WillFail;
}
// Check if there might be a bridging conversion.
if (source->isBridgeableObjectType() && mayBridgeToObjectiveC(M, target)) {
// Try to get the ObjC type which is bridged to target type.
assert(!target.isAnyExistentialType());
// ObjC-to-Swift casts may fail. And in most cases it is impossible to
// statically predict the outcome. So, let's be conservative here.
return DynamicCastFeasibility::MaySucceed;
}
if (target->isBridgeableObjectType() && mayBridgeToObjectiveC(M, source)) {
// Try to get the ObjC type which is bridged to source type.
assert(!source.isAnyExistentialType());
if (Type ObjCTy = M->getASTContext().getBridgedToObjC(M, source)) {
// If the bridged ObjC type is known, check if
// this type can be cast into target type.
return classifyDynamicCast(M,
ObjCTy->getCanonicalType(),
target,
/* isSourceTypeExact */ false, isWholeModuleOpts);
}
return DynamicCastFeasibility::MaySucceed;
}
// Check if it is a cast between bridged error types.
if (isError(M, source) && isError(M, target)) {
// TODO: Cast to NSError succeeds always.
return DynamicCastFeasibility::MaySucceed;
}
// Check for a viable collection cast.
if (auto sourceStruct = dyn_cast<BoundGenericStructType>(source)) {
if (auto targetStruct = dyn_cast<BoundGenericStructType>(target)) {
// Both types have to be the same kind of collection.
auto typeDecl = sourceStruct->getDecl();
if (typeDecl == targetStruct->getDecl()) {
auto sourceArgs = sourceStruct.getGenericArgs();
auto targetArgs = targetStruct.getGenericArgs();
// Note that we can never say that a collection cast is impossible:
// a cast can always succeed on an empty collection.
// Arrays and sets.
if (typeDecl == M->getASTContext().getArrayDecl() ||
typeDecl == M->getASTContext().getSetDecl()) {
auto valueFeasibility =
classifyDynamicCast(M, sourceArgs[0], targetArgs[0]);
return atWorst(valueFeasibility,
DynamicCastFeasibility::MaySucceed);
// Dictionaries.
} else if (typeDecl == M->getASTContext().getDictionaryDecl()) {
auto keyFeasibility =
classifyDynamicCast(M, sourceArgs[0], targetArgs[0]);
auto valueFeasibility =
classifyDynamicCast(M, sourceArgs[1], targetArgs[1]);
return atWorst(atBest(keyFeasibility, valueFeasibility),
DynamicCastFeasibility::MaySucceed);
}
}
}
}
return DynamicCastFeasibility::WillFail;
}
/// Try to classify the dynamic-cast relationship between two types.
DynamicCastFeasibility
swift::classifyDynamicCast(Module *M,
CanType source,
CanType target,
bool isSourceTypeExact,
bool isWholeModuleOpts) {
if (source == target) return DynamicCastFeasibility::WillSucceed;
auto sourceObject = source.getAnyOptionalObjectType();
auto targetObject = target.getAnyOptionalObjectType();
// A common level of optionality doesn't affect the feasibility.
if (sourceObject && targetObject) {
return classifyDynamicCast(M, sourceObject, targetObject);
// Nor does casting to a more optional type.
} else if (targetObject) {
return classifyDynamicCast(M, source, targetObject,
/* isSourceTypeExact */ false,
isWholeModuleOpts);
// Casting to a less-optional type can always fail.
} else if (sourceObject) {
return weakenSuccess(classifyDynamicCast(M, sourceObject, target,
/* isSourceTypeExact */ false,
isWholeModuleOpts));
}
assert(!sourceObject && !targetObject);
// Assume that casts to or from existential types or involving
// dependent types can always succeed. This is over-conservative.
if (source->hasArchetype() || source.isExistentialType() ||
target->hasArchetype() || target.isExistentialType()) {
auto *SourceNominalTy = source.getAnyNominal();
// Check conversions from non-protocol types into protocol types.
if (!source.isExistentialType() &&
SourceNominalTy &&
target.isExistentialType())
return classifyDynamicCastToProtocol(source, target, isWholeModuleOpts);
// 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;
}
return DynamicCastFeasibility::MaySucceed;
}
// Metatype casts.
if (auto sourceMetatype = dyn_cast<AnyMetatypeType>(source)) {
auto targetMetatype = dyn_cast<AnyMetatypeType>(target);
if (!targetMetatype) return DynamicCastFeasibility::WillFail;
source = sourceMetatype.getInstanceType();
target = targetMetatype.getInstanceType();
if (source == target &&
targetMetatype.isAnyExistentialType() ==
sourceMetatype.isAnyExistentialType())
return DynamicCastFeasibility::WillSucceed;
if (targetMetatype.isAnyExistentialType() &&
(isa<ProtocolType>(target) || isa<ProtocolCompositionType>(target))) {
auto Feasibility = classifyDynamicCastToProtocol(source,
target,
isWholeModuleOpts);
// Cast from existential metatype to existential metatype may still
// succeed, even if we cannot prove anything statically.
if (Feasibility != DynamicCastFeasibility::WillFail ||
!sourceMetatype.isAnyExistentialType())
return Feasibility;
}
// If isSourceTypeExact is true, we know we are casting the result of a
// MetatypeInst instruction.
if (isSourceTypeExact) {
// If source or target are existentials, then it can be cast
// successfully only into itself.
if ((target.isAnyExistentialType() || source.isAnyExistentialType()) &&
target != source)
return DynamicCastFeasibility::WillFail;
}
// Casts from class existential metatype into a concrete non-class metatype
// can never succeed.
if (source->isClassExistentialType() &&
!target.isAnyExistentialType() &&
!target.getClassOrBoundGenericClass())
return DynamicCastFeasibility::WillFail;
// TODO: prove that some conversions to existential metatype will
// obviously succeed/fail.
// TODO: prove that some conversions from class existential metatype
// to a concrete non-class metatype will obviously fail.
// TODO: class metatype to/from AnyObject
// TODO: protocol concrete metatype to/from ObjCProtocol
if (isa<ExistentialMetatypeType>(sourceMetatype) ||
isa<ExistentialMetatypeType>(targetMetatype))
return (getAnyMetatypeDepth(source) == getAnyMetatypeDepth(target)
? DynamicCastFeasibility::MaySucceed
: DynamicCastFeasibility::WillFail);
// If both metatypes are class metatypes, check if classes can be
// cast.
if (source.getClassOrBoundGenericClass() &&
target.getClassOrBoundGenericClass())
return classifyDynamicCast(M, source, target, false, isWholeModuleOpts);
// Different structs cannot be cast to each other.
if (source.getStructOrBoundGenericStruct() &&
target.getStructOrBoundGenericStruct() &&
source != target)
return DynamicCastFeasibility::WillFail;
// Different enums cannot be cast to each other.
if (source.getEnumOrBoundGenericEnum() &&
target.getEnumOrBoundGenericEnum() &&
source != target)
return DynamicCastFeasibility::WillFail;
// If we don't know any better, assume that the cast may succeed.
return DynamicCastFeasibility::MaySucceed;
}
// Function casts.
if (auto sourceFunction = dyn_cast<FunctionType>(source)) {
if (auto targetFunction = dyn_cast<FunctionType>(target)) {
// A function cast can succeed if the function types can be identical,
// or if the target type is throwier than the original.
// A non-throwing source function can be cast to a throwing target type,
// but not vice versa.
if (sourceFunction->throws() && !targetFunction->throws())
return DynamicCastFeasibility::WillFail;
// A noreturn source function can be cast to a returning target type,
// but not vice versa.
// (noreturn isn't really reified at runtime though.)
if (targetFunction->isNoReturn() && !sourceFunction->isNoReturn())
return DynamicCastFeasibility::WillFail;
// The cast can't change the representation at runtime.
if (targetFunction->getRepresentation()
!= sourceFunction->getRepresentation())
return DynamicCastFeasibility::WillFail;
if (sourceFunction.getInput() == targetFunction.getInput()
&& sourceFunction.getResult() == targetFunction.getResult())
return DynamicCastFeasibility::WillSucceed;
auto isSubstitutable = [](CanType a, CanType b) -> bool {
// FIXME: Unnecessarily conservative; should structurally check for
// substitutability.
return a == b || a->hasArchetype() || b->hasArchetype();
};
if (isSubstitutable(sourceFunction.getInput(), targetFunction.getInput())
&& isSubstitutable(targetFunction.getInput(),
targetFunction.getResult()))
return DynamicCastFeasibility::MaySucceed;
return DynamicCastFeasibility::WillFail;
}
}
// Class casts.
auto sourceClass = source.getClassOrBoundGenericClass();
auto targetClass = target.getClassOrBoundGenericClass();
if (sourceClass) {
if (targetClass) {
// Imported Objective-C generics don't check the generic parameters, which
// are lost at runtime.
if (sourceClass->usesObjCGenericsModel()) {
if (sourceClass == targetClass)
return DynamicCastFeasibility::WillSucceed;
if (targetClass->usesObjCGenericsModel()) {
// If both classes are ObjC generics, the cast may succeed if the
// classes are related, irrespective of their generic parameters.
auto isDeclSuperclass = [&](ClassDecl *proposedSuper,
ClassDecl *proposedSub) -> bool {
do {
if (proposedSuper == proposedSub)
return true;
} while ((proposedSub = proposedSub->getSuperclassDecl()));
return false;
};
if (isDeclSuperclass(sourceClass, targetClass))
return DynamicCastFeasibility::MaySucceed;
if (isDeclSuperclass(targetClass, sourceClass)) {
return DynamicCastFeasibility::WillSucceed;
}
return DynamicCastFeasibility::WillFail;
}
}
if (target->isExactSuperclassOf(source, nullptr))
return DynamicCastFeasibility::WillSucceed;
if (target->isBindableToSuperclassOf(source, nullptr))
return DynamicCastFeasibility::MaySucceed;
if (source->isBindableToSuperclassOf(target, nullptr))
return DynamicCastFeasibility::MaySucceed;
// FIXME: bridged types, e.g. CF <-> NS (but not for metatypes).
return DynamicCastFeasibility::WillFail;
}
// In the Objective-C runtime, class metatypes are also class instances.
// The cast may succeed if the target type can be inhabited by a class
// metatype.
// TODO: Narrow this to the sourceClass being exactly NSObject.
if (M->getASTContext().LangOpts.EnableObjCInterop) {
if (auto targetMeta = dyn_cast<MetatypeType>(target)) {
if (isa<ArchetypeType>(targetMeta.getInstanceType())
|| targetMeta.getInstanceType()->mayHaveSuperclass())
return DynamicCastFeasibility::MaySucceed;
} else if (isa<ExistentialMetatypeType>(target)) {
return DynamicCastFeasibility::MaySucceed;
}
}
}
// If the source is not existential, an archetype, or (under the ObjC runtime)
// a class, and the destination is a metatype, there is no way the cast can
// succeed.
if (target->is<AnyMetatypeType>()) return DynamicCastFeasibility::WillFail;
// FIXME: tuple conversions?
// FIXME: Be more careful with bridging conversions from
// NSArray, NSDictionary and NSSet as they may fail?
// Check if there might be a bridging conversion.
if (source->isBridgeableObjectType() && mayBridgeToObjectiveC(M, target)) {
// Try to get the ObjC type which is bridged to target type.
assert(!target.isAnyExistentialType());
Optional<Type> ObjCTy = M->getASTContext().getBridgedToObjC(
M, target, nullptr);
if (ObjCTy && ObjCTy.getValue()) {
// If the bridged ObjC type is known, check if
// source type can be cast into it.
return classifyDynamicCast(M, source,
ObjCTy.getValue().getCanonicalTypeOrNull(),
/* isSourceTypeExact */ false, isWholeModuleOpts);
}
return DynamicCastFeasibility::MaySucceed;
}
if (target->isBridgeableObjectType() && mayBridgeToObjectiveC(M, source)) {
// Try to get the ObjC type which is bridged to source type.
assert(!source.isAnyExistentialType());
Optional<Type> ObjCTy = M->getASTContext().getBridgedToObjC(
M, source, nullptr);
if (ObjCTy && ObjCTy.getValue()) {
// If the bridged ObjC type is known, check if
// this type can be cast into target type.
return classifyDynamicCast(M,
ObjCTy.getValue().getCanonicalTypeOrNull(),
target,
/* isSourceTypeExact */ false, isWholeModuleOpts);
}
return DynamicCastFeasibility::MaySucceed;
}
// Check if it is a cast between bridged error types.
if (isError(M, source) && isError(M, target)) {
// TODO: Cast to NSError succeeds always.
return DynamicCastFeasibility::MaySucceed;
}
return DynamicCastFeasibility::WillFail;
}