public unsafe bool TryGetMetadataForNamedType(RuntimeTypeHandle runtimeTypeHandle, out MetadataReader metadataReader, out TypeDefinitionHandle typeDefHandle)
        {
            // Iterate over all modules, starting with the module that defines the EEType
            foreach (IntPtr moduleHandle in ModuleList.Enumerate(RuntimeAugments.GetModuleFromTypeHandle(runtimeTypeHandle)))
            {
                NativeReader typeMapReader;
                if (TryGetNativeReaderForBlob(moduleHandle, ReflectionMapBlob.TypeMap, out typeMapReader))
                {
                    NativeParser typeMapParser = new NativeParser(typeMapReader, 0);
                    NativeHashtable typeHashtable = new NativeHashtable(typeMapParser);

                    ExternalReferencesTable externalReferences = default(ExternalReferencesTable);
                    externalReferences.InitializeCommonFixupsTable(moduleHandle);

                    var lookup = typeHashtable.Lookup(runtimeTypeHandle.GetHashCode());
                    NativeParser entryParser;
                    while (!(entryParser = lookup.GetNext()).IsNull)
                    {
                        RuntimeTypeHandle foundType = externalReferences.GetRuntimeTypeHandleFromIndex(entryParser.GetUnsigned());
                        if (foundType.Equals(runtimeTypeHandle))
                        {
                            Handle entryMetadataHandle = entryParser.GetUnsigned().AsHandle();
                            if (entryMetadataHandle.HandleType == HandleType.TypeDefinition)
                            {
                                metadataReader = ModuleList.Instance.GetMetadataReaderForModule(moduleHandle);
                                typeDefHandle = entryMetadataHandle.ToTypeDefinitionHandle(metadataReader);
                                return true;
                            }
                        }
                    }
                }
            }

            metadataReader = null;
            typeDefHandle = default(TypeDefinitionHandle);

            return false;
        }
        private unsafe bool ResolveGenericVirtualMethodTarget_Static(RuntimeTypeHandle targetTypeHandle, RuntimeTypeHandle declaringType, RuntimeTypeHandle[] genericArguments, MethodNameAndSignature callingMethodNameAndSignature, out IntPtr methodPointer, out IntPtr dictionaryPointer)
        {
            methodPointer = dictionaryPointer = IntPtr.Zero;

            // Get the open type definition of the containing type of the generic virtual method being resolved
            RuntimeTypeHandle openCallingTypeHandle = GetTypeDefinition(declaringType);

            // Get the open type definition of the current type of the object instance on which the GVM is being resolved
            RuntimeTypeHandle openTargetTypeHandle = GetTypeDefinition(targetTypeHandle);

            int hashCode = openCallingTypeHandle.GetHashCode();
            hashCode = ((hashCode << 13) ^ hashCode) ^ openTargetTypeHandle.GetHashCode();

#if REFLECTION_EXECUTION_TRACE
            ReflectionExecutionLogger.WriteLine("GVM Target Resolution = " + GetTypeNameDebug(targetTypeHandle) + "." + callingMethodNameAndSignature.Name);
#endif

            foreach (IntPtr moduleHandle in ModuleList.Enumerate(RuntimeAugments.GetModuleFromTypeHandle(openTargetTypeHandle)))
            {
                NativeReader gvmTableReader;
                if (!TryGetNativeReaderForBlob(moduleHandle, ReflectionMapBlob.GenericVirtualMethodTable, out gvmTableReader))
                    continue;

                NativeReader nativeLayoutReader;
                if (!TryGetNativeReaderForBlob(moduleHandle, ReflectionMapBlob.NativeLayoutInfo, out nativeLayoutReader))
                    continue;

                NativeParser gvmTableParser = new NativeParser(gvmTableReader, 0);
                NativeHashtable gvmHashtable = new NativeHashtable(gvmTableParser);
                ExternalReferencesTable extRefs = default(ExternalReferencesTable);
                extRefs.InitializeCommonFixupsTable(moduleHandle);

                var lookup = gvmHashtable.Lookup(hashCode);

                NativeParser entryParser;
                while (!(entryParser = lookup.GetNext()).IsNull)
                {
                    RuntimeTypeHandle parsedCallingTypeHandle = extRefs.GetRuntimeTypeHandleFromIndex(entryParser.GetUnsigned());
                    if (!parsedCallingTypeHandle.Equals(openCallingTypeHandle))
                        continue;

                    RuntimeTypeHandle parsedTargetTypeHandle = extRefs.GetRuntimeTypeHandleFromIndex(entryParser.GetUnsigned());
                    if (!parsedTargetTypeHandle.Equals(openTargetTypeHandle))
                        continue;

                    uint parsedCallingNameAndSigToken = extRefs.GetRvaFromIndex(entryParser.GetUnsigned());
                    MethodNameAndSignature parsedCallingNameAndSignature = GetMethodNameAndSignatureFromNativeReader(nativeLayoutReader, parsedCallingNameAndSigToken);

                    if (!parsedCallingNameAndSignature.Equals(callingMethodNameAndSignature))
                        continue;

                    uint parsedTargetMethodNameAndSigToken = extRefs.GetRvaFromIndex(entryParser.GetUnsigned());
                    MethodNameAndSignature targetMethodNameAndSignature = GetMethodNameAndSignatureFromNativeReader(nativeLayoutReader, parsedTargetMethodNameAndSigToken);

                    Debug.Assert(targetMethodNameAndSignature != null);

                    return TryGetGenericVirtualMethodPointer(targetTypeHandle, targetMethodNameAndSignature, genericArguments, out methodPointer, out dictionaryPointer);
                }
            }

            return false;
        }
        private bool ResolveInterfaceGenericVirtualMethodSlot_Static(RuntimeTypeHandle targetTypeHandle, ref RuntimeTypeHandle declaringType, ref MethodNameAndSignature methodNameAndSignature)
        {
            // Get the open type definition of the containing type of the generic virtual method being resolved
            RuntimeTypeHandle openCallingTypeHandle = GetTypeDefinition(declaringType);

            // Get the open type definition of the current type of the object instance on which the GVM is being resolved
            RuntimeTypeHandle openTargetTypeHandle;
            RuntimeTypeHandle[] targetTypeInstantiation;
            openTargetTypeHandle = GetOpenTypeDefinition(targetTypeHandle, out targetTypeInstantiation);

#if REFLECTION_EXECUTION_TRACE
            ReflectionExecutionLogger.WriteLine("INTERFACE GVM call = " + GetTypeNameDebug(declaringType) + "." + methodNameAndSignature.Name);
#endif

            foreach (IntPtr moduleHandle in ModuleList.Enumerate(RuntimeAugments.GetModuleFromTypeHandle(openTargetTypeHandle)))
            {
                NativeReader gvmTableReader;
                if (!TryGetNativeReaderForBlob(moduleHandle, ReflectionMapBlob.InterfaceGenericVirtualMethodTable, out gvmTableReader))
                    continue;

                NativeReader nativeLayoutReader;
                if (!TryGetNativeReaderForBlob(moduleHandle, ReflectionMapBlob.NativeLayoutInfo, out nativeLayoutReader))
                    continue;

                NativeParser gvmTableParser = new NativeParser(gvmTableReader, 0);
                NativeHashtable gvmHashtable = new NativeHashtable(gvmTableParser);

                ExternalReferencesTable extRefs = default(ExternalReferencesTable);
                extRefs.InitializeCommonFixupsTable(moduleHandle);

                var lookup = gvmHashtable.Lookup(openCallingTypeHandle.GetHashCode());

                NativeParser entryParser;
                while (!(entryParser = lookup.GetNext()).IsNull)
                {
                    RuntimeTypeHandle interfaceTypeHandle = extRefs.GetRuntimeTypeHandleFromIndex(entryParser.GetUnsigned());
                    if (!openCallingTypeHandle.Equals(interfaceTypeHandle))
                        continue;

                    uint nameAndSigToken = extRefs.GetRvaFromIndex(entryParser.GetUnsigned());
                    MethodNameAndSignature interfaceMethodNameAndSignature = GetMethodNameAndSignatureFromNativeReader(nativeLayoutReader, nameAndSigToken);

                    if (!interfaceMethodNameAndSignature.Equals(methodNameAndSignature))
                        continue;

                    // For each of the possible GVM slot targets for the current interface call, we will do the following:
                    //
                    //  Step 1: Scan the types that currently provide implementations for the current GVM slot target, and look
                    //          for ones that match the target object's type.
                    //
                    //  Step 2: For each type that we find in step #1, get a list of all the interfaces that the current GVM target
                    //          provides an implementation for
                    //
                    //  Step 3: For each interface in the list in step #2, parse the signature of that interface, do the generic argument
                    //          substitution (in case of a generic interface), and check if this interface signature is assignable from the
                    //          calling interface signature (from the name and sig input). if there is an exact match based on 
                    //          interface type, then we've found the right slot. Otherwise, re-scan the entry again and see if some interface 
                    //          type is compatible with the initial slots interface by means of variance. 
                    //          This is done by calling the TypeLoaderEnvironment helper function.
                    //
                    // Example:
                    //      public interface IFoo<out T, out U>
                    //      {
                    //          string M1<V>();
                    //      }
                    //      public class Foo1<T, U> : IFoo<T, U>, IFoo<Kvp<T, string>, U>
                    //      {
                    //          string IFoo<T, U>.M1<V>() { ... }
                    //          public virtual string M1<V>() { ... }
                    //      }
                    //      public class Foo2<T, U> : Foo1<object, U>, IFoo<U, T>
                    //      {
                    //          string IFoo<U, T>.M1<V>() { ... }
                    //      }        
                    //
                    //  GVM Table layout for IFoo<T, U>.M1<V>:
                    //  {
                    //      InterfaceTypeHandle = IFoo<T, U>
                    //      InterfaceMethodNameAndSignature = { "M1", SigOf(string M1) }
                    //      GVMTargetSlots[] = 
                    //      {
                    //          {
                    //              TargetMethodNameAndSignature = { "M1", SigOf(M1) }
                    //              TargetTypeHandle = Foo1<T, U>
                    //              ImplementingTypes[] = {
                    //                  ImplementingTypeHandle = Foo1<T, U>
                    //                  ImplementedInterfacesSignatures[] = { SigOf(IFoo<!0, !1>) }
                    //              }
                    //          },
                    //
                    //          {
                    //              TargetMethodNameAndSignature = { "M1", SigOf(M1) }
                    //              TargetTypeHandle = Foo1<T, U>
                    //              ImplementingTypes[] = {
                    //                  ImplementingTypeHandle = Foo1<T, U>
                    //                  ImplementedInterfacesSignatures[] = { SigOf(IFoo<Kvp<!0, string>, !1>) }
                    //              }
                    //          },
                    //
                    //          {
                    //              TargetMethodNameAndSignature = { "M1", SigOf(M1) }
                    //              TargetTypeHandle = Foo2<T, U>
                    //              ImplementingTypes = {
                    //                  ImplementingTypeHandle = Foo2<T, U>
                    //                  ImplementedInterfacesSignatures[] = { SigOf(IFoo<!1, !0>) }
                    //              }
                    //          }, 
                    //      }
                    //  }
                    //

                    uint currentOffset = entryParser.Offset;

                    // Non-variant dispatch of a variant generic interface generic virtual method.
                    if (FindMatchingInterfaceSlot(moduleHandle, nativeLayoutReader, ref entryParser, ref extRefs, ref declaringType, ref methodNameAndSignature, openTargetTypeHandle, targetTypeInstantiation, false))
                    {
                        return true;
                    }

                    entryParser.Offset = currentOffset;

                    // Variant dispatch of a variant generic interface generic virtual method.
                    if (FindMatchingInterfaceSlot(moduleHandle, nativeLayoutReader, ref entryParser, ref extRefs, ref declaringType, ref methodNameAndSignature, openTargetTypeHandle, targetTypeInstantiation, true))
                    {
                        return true;
                    }
                }
            }

            return false;
        }
        public unsafe bool TryGetNamedTypeForMetadata(MetadataReader metadataReader, TypeDefinitionHandle typeDefHandle, out RuntimeTypeHandle runtimeTypeHandle)
        {
            int hashCode = typeDefHandle.ComputeHashCode(metadataReader);

            IntPtr moduleHandle = ModuleList.Instance.GetModuleForMetadataReader(metadataReader);

            NativeReader typeMapReader;
            if (TryGetNativeReaderForBlob(moduleHandle, ReflectionMapBlob.TypeMap, out typeMapReader))
            {
                NativeParser typeMapParser = new NativeParser(typeMapReader, 0);
                NativeHashtable typeHashtable = new NativeHashtable(typeMapParser);

                ExternalReferencesTable externalReferences = default(ExternalReferencesTable);
                externalReferences.InitializeCommonFixupsTable(moduleHandle);

                var lookup = typeHashtable.Lookup(hashCode);
                NativeParser entryParser;
                while (!(entryParser = lookup.GetNext()).IsNull)
                {
                    var foundTypeIndex = entryParser.GetUnsigned();
                    if (entryParser.GetUnsigned().AsHandle().Equals(typeDefHandle))
                    {
                        runtimeTypeHandle = externalReferences.GetRuntimeTypeHandleFromIndex(foundTypeIndex);
                        return true;
                    }
                }
            }

            runtimeTypeHandle = default(RuntimeTypeHandle);
            return false;
        }
        /// <summary>
        /// Try to look up non-gc/gc static effective field bases for a non-generic non-dynamic type.
        /// </summary>
        /// <param name="declaringTypeHandle">Declaring type for the method</param>
        /// <param name="fieldAccessKind">type of static base to find</param>
        /// <param name="staticsRegionAddress">Output - statics region address info</param>
        /// <returns>true when found, false otherwise</returns>
        private static unsafe bool TryGetStaticFieldBaseFromFieldAccessMap(
            RuntimeTypeHandle declaringTypeHandle,
            FieldAccessStaticDataKind fieldAccessKind,
            out IntPtr staticsRegionAddress)
        {
            staticsRegionAddress = IntPtr.Zero;
            byte* comparableStaticRegionAddress = null;

            CanonicallyEquivalentEntryLocator canonWrapper = new CanonicallyEquivalentEntryLocator(declaringTypeHandle, CanonicalFormKind.Specific);

            // This function only finds results for non-dynamic, non-generic types
            if (RuntimeAugments.IsDynamicType(declaringTypeHandle) || RuntimeAugments.IsGenericType(declaringTypeHandle))
                return false;

            foreach (IntPtr mappingTableModule in ModuleList.Enumerate(RuntimeAugments.GetModuleFromTypeHandle(declaringTypeHandle)))
            {
                NativeReader fieldMapReader;
                if (!TryGetNativeReaderForBlob(mappingTableModule, ReflectionMapBlob.FieldAccessMap, out fieldMapReader))
                    continue;

                NativeParser fieldMapParser = new NativeParser(fieldMapReader, 0);
                NativeHashtable fieldHashtable = new NativeHashtable(fieldMapParser);

                ExternalReferencesTable externalReferences = default(ExternalReferencesTable);
                if (!externalReferences.InitializeCommonFixupsTable(mappingTableModule))
                {
                    continue;
                }

                var lookup = fieldHashtable.Lookup(canonWrapper.LookupHashCode);

                NativeParser entryParser;
                while (!(entryParser = lookup.GetNext()).IsNull)
                {
                    // Grammar of a hash table entry:
                    // Flags + DeclaringType + MdHandle or Name + Cookie or Ordinal or Offset

                    FieldTableFlags entryFlags = (FieldTableFlags)entryParser.GetUnsigned();

                    Debug.Assert(!entryFlags.HasFlag(FieldTableFlags.IsUniversalCanonicalEntry));

                    if (!entryFlags.HasFlag(FieldTableFlags.Static))
                        continue;

                    switch (fieldAccessKind)
                    {
                        case FieldAccessStaticDataKind.NonGC:
                            if (entryFlags.HasFlag(FieldTableFlags.IsGcSection))
                                continue;
                            if (entryFlags.HasFlag(FieldTableFlags.ThreadStatic))
                                continue;
                            break;
                        case FieldAccessStaticDataKind.GC:
                            if (!entryFlags.HasFlag(FieldTableFlags.IsGcSection))
                                continue;
                            if (entryFlags.HasFlag(FieldTableFlags.ThreadStatic))
                                continue;
                            break;

                        case FieldAccessStaticDataKind.TLS:
                        default:
                            // TODO! TLS statics
                            Environment.FailFast("TLS static field access not yet supported");
                            return false;
                    }

                    RuntimeTypeHandle entryDeclaringTypeHandle = externalReferences.GetRuntimeTypeHandleFromIndex(entryParser.GetUnsigned());
                    if (!entryDeclaringTypeHandle.Equals(declaringTypeHandle))
                        continue;

                    if (entryFlags.HasFlag(FieldTableFlags.HasMetadataHandle))
                    {
                        // skip metadata handle
                        entryParser.GetUnsigned();
                    }
                    else
                    {
                        // skip field name
                        entryParser.SkipString();
                    }

                    int cookieOrOffsetOrOrdinal = (int)entryParser.GetUnsigned();
                    int fieldOffset = (int)externalReferences.GetRvaFromIndex((uint)cookieOrOffsetOrOrdinal);

                    IntPtr fieldAddress = RvaToNonGenericStaticFieldAddress(
                        mappingTableModule, fieldOffset);

                    if ((comparableStaticRegionAddress == null) || (comparableStaticRegionAddress > fieldAddress.ToPointer()))
                    {
                        comparableStaticRegionAddress = (byte*)fieldAddress.ToPointer();
                    }
                }

                // Static fields for a type can only be found in at most one module
                if (comparableStaticRegionAddress != null)
                    break;
            }

            if (comparableStaticRegionAddress != null)
            {
                staticsRegionAddress = new IntPtr(comparableStaticRegionAddress);
                return true;
            }
            else
            {
                return false;
            }
        }
        /// <summary>
        /// Try to look up field acccess info for given canon in metadata blobs for all available modules.
        /// </summary>
        /// <param name="metadataReader">Metadata reader for the declaring type</param>
        /// <param name="declaringTypeHandle">Declaring type for the method</param>
        /// <param name="fieldHandle">Field handle</param>
        /// <param name="canonFormKind">Canonical form to use</param>
        /// <param name="fieldAccessMetadata">Output - metadata information for field accessor construction</param>
        /// <returns>true when found, false otherwise</returns>
        private static bool TryGetFieldAccessMetadataFromFieldAccessMap(
            MetadataReader metadataReader,
            RuntimeTypeHandle declaringTypeHandle,
            FieldHandle fieldHandle,
            CanonicalFormKind canonFormKind,
            ref FieldAccessMetadata fieldAccessMetadata)
        {
            CanonicallyEquivalentEntryLocator canonWrapper = new CanonicallyEquivalentEntryLocator(declaringTypeHandle, canonFormKind);
            IntPtr fieldHandleModule = ModuleList.Instance.GetModuleForMetadataReader(metadataReader);
            bool isDynamicType = RuntimeAugments.IsDynamicType(declaringTypeHandle);
            string fieldName = null;
            RuntimeTypeHandle declaringTypeHandleDefinition = Instance.GetTypeDefinition(declaringTypeHandle);

            foreach (IntPtr mappingTableModule in ModuleList.Enumerate(RuntimeAugments.GetModuleFromTypeHandle(declaringTypeHandle)))
            {
                NativeReader fieldMapReader;
                if (!TryGetNativeReaderForBlob(mappingTableModule, ReflectionMapBlob.FieldAccessMap, out fieldMapReader))
                    continue;

                NativeParser fieldMapParser = new NativeParser(fieldMapReader, 0);
                NativeHashtable fieldHashtable = new NativeHashtable(fieldMapParser);

                ExternalReferencesTable externalReferences = default(ExternalReferencesTable);
                if (!externalReferences.InitializeCommonFixupsTable(mappingTableModule))
                {
                    continue;
                }

                var lookup = fieldHashtable.Lookup(canonWrapper.LookupHashCode);

                NativeParser entryParser;
                while (!(entryParser = lookup.GetNext()).IsNull)
                {
                    // Grammar of a hash table entry:
                    // Flags + DeclaringType + MdHandle or Name + Cookie or Ordinal or Offset

                    FieldTableFlags entryFlags = (FieldTableFlags)entryParser.GetUnsigned();

                    if ((canonFormKind == CanonicalFormKind.Universal) != entryFlags.HasFlag(FieldTableFlags.IsUniversalCanonicalEntry))
                        continue;

                    RuntimeTypeHandle entryDeclaringTypeHandle = externalReferences.GetRuntimeTypeHandleFromIndex(entryParser.GetUnsigned());
                    if (!entryDeclaringTypeHandle.Equals(declaringTypeHandle)
                        && !canonWrapper.IsCanonicallyEquivalent(entryDeclaringTypeHandle))
                        continue;

                    if (entryFlags.HasFlag(FieldTableFlags.HasMetadataHandle))
                    {
                        Handle entryFieldHandle = (((int)HandleType.Field << 24) | (int)entryParser.GetUnsigned()).AsHandle();
                        if (!fieldHandle.Equals(entryFieldHandle))
                            continue;
                    }
                    else
                    {
                        if (fieldName == null)
                        {
                            MetadataReader mdReader;
                            TypeDefinitionHandle typeDefHandleUnused;
                            bool success = Instance.TryGetMetadataForNamedType(
                                declaringTypeHandleDefinition,
                                out mdReader,
                                out typeDefHandleUnused);
                            Debug.Assert(success);

                            fieldName = mdReader.GetString(fieldHandle.GetField(mdReader).Name);
                        }

                        string entryFieldName = entryParser.GetString();

                        if (fieldName != entryFieldName)
                            continue;
                    }

                    int cookieOrOffsetOrOrdinal = (int)entryParser.GetUnsigned();
                    int fieldOffset;
                    IntPtr fieldAddressCookie = IntPtr.Zero;

                    if (canonFormKind == CanonicalFormKind.Universal)
                    {
                        if (!TypeLoaderEnvironment.Instance.TryGetFieldOffset(declaringTypeHandle, (uint)cookieOrOffsetOrOrdinal, out fieldOffset))
                        {
                            Debug.Assert(false);
                            return false;
                        }
                    }
                    else
                    {
#if CORERT
                        fieldOffset = cookieOrOffsetOrOrdinal;
#else
                        fieldOffset = (int)externalReferences.GetRvaFromIndex((uint)cookieOrOffsetOrOrdinal);
#endif
                    }

                    if ((entryFlags & FieldTableFlags.StorageClass) == FieldTableFlags.ThreadStatic)
                    {
                        if (canonFormKind != CanonicalFormKind.Universal)
                        {
                            fieldAddressCookie = RvaToNonGenericStaticFieldAddress(mappingTableModule, fieldOffset);
                        }

                        if (!entryDeclaringTypeHandle.Equals(declaringTypeHandle))
                        {
                            // In this case we didn't find an exact match, but we did find a canonically equivalent match
                            // We might be in the dynamic type case, or the canonically equivalent, but not the same case.

                            if (!RuntimeAugments.IsDynamicType(declaringTypeHandle))
                            {
                                int offsetToCreateCookieFor = fieldOffset;
                                // We're working with a statically generated type, but we didn't find an exact match in the tables
                                if (canonFormKind != CanonicalFormKind.Universal)
                                    offsetToCreateCookieFor = checked((int)TypeLoaderEnvironment.GetThreadStaticTypeOffsetFromThreadStaticCookie(fieldAddressCookie));

                                fieldAddressCookie = TypeLoaderEnvironment.Instance.TryGetThreadStaticFieldOffsetCookieForTypeAndFieldOffset(declaringTypeHandle, checked((uint)offsetToCreateCookieFor));
                            }
                        }
                    }

                    fieldAccessMetadata.MappingTableModule = mappingTableModule;
                    fieldAccessMetadata.Cookie = fieldAddressCookie;
                    fieldAccessMetadata.Flags = entryFlags;
                    fieldAccessMetadata.Offset = fieldOffset;
                    return true;
                }
            }

            return false;
        }