// Returns an address in the module most closely associated with this EEType that can be handed to
// EH.GetClasslibException and use to locate the compute the correct exception type. In most cases
// this is just the EEType pointer itself, but when this type represents a generic that has been
// unified at runtime (and thus the EEType pointer resides in the process heap rather than a specific
// module) we need to do some work.
internal unsafe IntPtr GetAssociatedModuleAddress()
{
fixed(EEType *pThis = &this)
{
if (!IsRuntimeAllocated && !IsDynamicType)
{
return((IntPtr)pThis);
}
// There are currently three types of runtime allocated EETypes, arrays, pointers, and generic types.
// Arrays/Pointers can be handled by looking at their element type.
if (IsParameterizedType)
{
return(pThis->RelatedParameterType->GetAssociatedModuleAddress());
}
// Generic types are trickier. Often we could look at the parent type (since eventually it
// would derive from the class library's System.Object which is definitely not runtime
// allocated). But this breaks down for generic interfaces. Instead we fetch the generic
// instantiation information and use the generic type definition, which will always be module
// local. We know this lookup will succeed since we're dealing with a unified generic type
// and the unification process requires this metadata.
EETypeRef * pInstantiation;
int arity;
GenericVariance *pVarianceInfo;
EEType * pGenericType = InternalCalls.RhGetGenericInstantiation(pThis,
&arity,
&pInstantiation,
&pVarianceInfo);
Debug.Assert(pGenericType != null, "Generic type expected");
return((IntPtr)pGenericType);
}
}
// Compare two types to see if they are compatible via generic variance.
static private unsafe bool TypesAreCompatibleViaGenericVariance(EEType *pSourceType, EEType *pTargetType)
{
// Get generic instantiation metadata for both types.
EETypeRef * pTargetInstantiation;
int targetArity;
GenericVariance *pTargetVarianceInfo;
EEType * pTargetGenericType = InternalCalls.RhGetGenericInstantiation(pTargetType,
&targetArity,
&pTargetInstantiation,
&pTargetVarianceInfo);
Debug.Assert(pTargetVarianceInfo != null, "did not expect empty variance info");
EETypeRef * pSourceInstantiation;
int sourceArity;
GenericVariance *pSourceVarianceInfo;
EEType * pSourceGenericType = InternalCalls.RhGetGenericInstantiation(pSourceType,
&sourceArity,
&pSourceInstantiation,
&pSourceVarianceInfo);
Debug.Assert(pSourceVarianceInfo != null, "did not expect empty variance info");
// If the generic types aren't the same then the types aren't compatible.
if (pSourceGenericType == pTargetGenericType)
{
// The types represent different instantiations of the same generic type. The
// arity of both had better be the same.
Debug.Assert(targetArity == sourceArity, "arity mismatch betweeen generic instantiations");
// Compare the instantiations to see if they're compatible taking variance into account.
if (TypeParametersAreCompatible(targetArity,
pSourceInstantiation,
pTargetInstantiation,
pTargetVarianceInfo,
false))
{
return(true);
}
}
return(false);
}
static internal unsafe bool ImplementsInterface(EEType *pObjType, EEType *pTargetType)
{
Debug.Assert(!pTargetType->IsParameterizedType, "did not expect paramterized type");
Debug.Assert(pTargetType->IsInterface, "IsInstanceOfInterface called with non-interface EEType");
// This can happen with generic interface types
// Debug.Assert(!pTargetType->IsCloned, "cloned interface types are disallowed");
// canonicalize target type
if (pTargetType->IsCloned)
{
pTargetType = pTargetType->CanonicalEEType;
}
int numInterfaces = pObjType->NumInterfaces;
EEInterfaceInfo *interfaceMap = pObjType->InterfaceMap;
for (int i = 0; i < numInterfaces; i++)
{
EEType *pInterfaceType = interfaceMap[i].InterfaceType;
// canonicalize the interface type
if (pInterfaceType->IsCloned)
{
pInterfaceType = pInterfaceType->CanonicalEEType;
}
if (pInterfaceType == pTargetType)
{
return(true);
}
}
// We did not find the interface type in the list of supported interfaces. There's still one
// chance left: if the target interface is generic and one or more of its type parameters is co or
// contra variant then the object can still match if it implements a different instantiation of
// the interface with type compatible generic arguments.
//
// An additional edge case occurs because of array covariance. This forces us to treat any generic
// interfaces implemented by arrays as covariant over their one type parameter.
bool fArrayCovariance = pObjType->IsArray;
if (pTargetType->HasGenericVariance || (fArrayCovariance && pTargetType->IsGeneric))
{
// Grab details about the instantiation of the target generic interface.
EETypeRef * pTargetInstantiation;
int targetArity;
GenericVariance *pTargetVarianceInfo;
EEType * pTargetGenericType = InternalCalls.RhGetGenericInstantiation(pTargetType,
&targetArity,
&pTargetInstantiation,
&pTargetVarianceInfo);
Debug.Assert(pTargetVarianceInfo != null, "did not expect empty variance info");
for (int i = 0; i < numInterfaces; i++)
{
EEType *pInterfaceType = interfaceMap[i].InterfaceType;
// We can ignore interfaces which are not also marked as having generic variance
// unless we're dealing with array covariance.
if (pInterfaceType->HasGenericVariance || (fArrayCovariance && pInterfaceType->IsGeneric))
{
// Grab instantiation details for the candidate interface.
EETypeRef * pInterfaceInstantiation;
int interfaceArity;
GenericVariance *pInterfaceVarianceInfo;
EEType * pInterfaceGenericType = InternalCalls.RhGetGenericInstantiation(pInterfaceType,
&interfaceArity,
&pInterfaceInstantiation,
&pInterfaceVarianceInfo);
Debug.Assert(pInterfaceVarianceInfo != null, "did not expect empty variance info");
// If the generic types aren't the same then the types aren't compatible.
if (pInterfaceGenericType != pTargetGenericType)
{
continue;
}
// The types represent different instantiations of the same generic type. The
// arity of both had better be the same.
Debug.Assert(targetArity == interfaceArity, "arity mismatch betweeen generic instantiations");
// Compare the instantiations to see if they're compatible taking variance into account.
if (TypeParametersAreCompatible(targetArity,
pInterfaceInstantiation,
pTargetInstantiation,
pTargetVarianceInfo,
fArrayCovariance))
{
return(true);
}
}
}
}
return(false);
}
private static bool FindImplSlotInSimpleMap(EEType *pTgtType,
EEType *pItfType,
UInt32 itfSlotNumber,
UInt16 *pImplSlotNumber,
bool actuallyCheckVariance)
{
Debug.Assert(pTgtType->HasDispatchMap, "Missing dispatch map");
EEType * pItfOpenGenericType = null;
EETypeRef * pItfInstantiation = null;
int itfArity = 0;
GenericVariance *pItfVarianceInfo = null;
bool fCheckVariance = false;
bool fArrayCovariance = false;
if (actuallyCheckVariance)
{
fCheckVariance = pItfType->HasGenericVariance;
fArrayCovariance = pTgtType->IsArray;
// Non-arrays can follow array variance rules iff
// 1. They have one generic parameter
// 2. That generic parameter is array covariant.
//
// This special case is to allow array enumerators to work
if (!fArrayCovariance && pTgtType->HasGenericVariance)
{
EETypeRef * pTgtInstantiation;
int tgtEntryArity;
GenericVariance *pTgtVarianceInfo;
EEType * pTgtEntryGenericType = InternalCalls.RhGetGenericInstantiation(pTgtType,
&tgtEntryArity,
&pTgtInstantiation,
&pTgtVarianceInfo);
if ((tgtEntryArity == 1) && pTgtVarianceInfo[0] == GenericVariance.ArrayCovariant)
{
fArrayCovariance = true;
}
}
// Arrays are covariant even though you can both get and set elements (type safety is maintained by
// runtime type checks during set operations). This extends to generic interfaces implemented on those
// arrays. We handle this by forcing all generic interfaces on arrays to behave as though they were
// covariant (over their one type parameter corresponding to the array element type).
if (fArrayCovariance && pItfType->IsGeneric)
{
fCheckVariance = true;
}
// If there is no variance checking, there is no operation to perform. (The non-variance check loop
// has already completed)
if (!fCheckVariance)
{
return(false);
}
}
DispatchMap * pMap = pTgtType->DispatchMap;
DispatchMapEntry *i = &pMap->_dispatchMap;
DispatchMapEntry *iEnd = (&pMap->_dispatchMap) + pMap->_entryCount;
for (; i != iEnd; ++i)
{
if (i->_usInterfaceMethodSlot == itfSlotNumber)
{
EEType *pCurEntryType =
pTgtType->InterfaceMap[i->_usInterfaceIndex].InterfaceType;
if (pCurEntryType->IsCloned)
{
pCurEntryType = pCurEntryType->CanonicalEEType;
}
if (pCurEntryType == pItfType)
{
*pImplSlotNumber = i->_usImplMethodSlot;
return(true);
}
else if (fCheckVariance && ((fArrayCovariance && pCurEntryType->IsGeneric) || pCurEntryType->HasGenericVariance))
{
// Interface types don't match exactly but both the target interface and the current interface
// in the map are marked as being generic with at least one co- or contra- variant type
// parameter. So we might still have a compatible match.
// Retrieve the unified generic instance for the callsite interface if we haven't already (we
// lazily get this then cache the result since the lookup isn't necessarily cheap).
if (pItfOpenGenericType == null)
{
pItfOpenGenericType = InternalCalls.RhGetGenericInstantiation(pItfType,
&itfArity,
&pItfInstantiation,
&pItfVarianceInfo);
}
// Retrieve the unified generic instance for the interface we're looking at in the map.
// Grab instantiation details for the candidate interface.
EETypeRef * pCurEntryInstantiation;
int curEntryArity;
GenericVariance *pCurEntryVarianceInfo;
EEType * pCurEntryGenericType = InternalCalls.RhGetGenericInstantiation(pCurEntryType,
&curEntryArity,
&pCurEntryInstantiation,
&pCurEntryVarianceInfo);
// If the generic types aren't the same then the types aren't compatible.
if (pItfOpenGenericType != pCurEntryGenericType)
{
continue;
}
// The types represent different instantiations of the same generic type. The
// arity of both had better be the same.
Debug.Assert(itfArity == curEntryArity, "arity mismatch betweeen generic instantiations");
if (TypeCast.TypeParametersAreCompatible(itfArity, pCurEntryInstantiation, pItfInstantiation, pItfVarianceInfo, fArrayCovariance))
{
*pImplSlotNumber = i->_usImplMethodSlot;
return(true);
}
}
}
}
return(false);
}
