Refactor missing reference errors to allow not throwing for all cases (#50437)

- Build the concept of a cacheable resolution failure
- Plumb it through the Ecma type loader and the required public api surfaces
- Use it within the Mibc parser to avoid throwing

3 files changed, 27 insertions, 9 deletions

diff --git a/src/coreclr/tools/aot/ILCompiler.ReadyToRun/IBC/IBCProfileParser.cs b/src/coreclr/tools/aot/ILCompiler.ReadyToRun/IBC/IBCProfileParser.cs
index b26d9ab6226..8b419d4b395 100644
--- a/src/coreclr/tools/aot/ILCompiler.ReadyToRun/IBC/IBCProfileParser.cs
+++ b/src/coreclr/tools/aot/ILCompiler.ReadyToRun/IBC/IBCProfileParser.cs
@@ -106,7 +106,7 @@ namespace ILCompiler.IBC
                         case CorTokenType.mdtMethodDef:
                         case CorTokenType.mdtMemberRef:
                         case CorTokenType.mdtMethodSpec:
-                            object metadataObject = ecmaModule.GetObject(System.Reflection.Metadata.Ecma335.MetadataTokens.EntityHandle((int)entry.Token));
+                            object metadataObject = ecmaModule.GetObject(System.Reflection.Metadata.Ecma335.MetadataTokens.EntityHandle((int)entry.Token), NotFoundBehavior.ReturnNull);
                             if (metadataObject is MethodDesc)
                             {
                                 associatedMethod = (MethodDesc)metadataObject;
@@ -346,7 +346,7 @@ namespace ILCompiler.IBC
                         if (!(m is EcmaModule))
                             continue;
 
-                        foundType = (EcmaType)m.GetType(typeNamespace, typeName, throwIfNotFound: false);
+                        foundType = (EcmaType)m.GetType(typeNamespace, typeName, NotFoundBehavior.ReturnNull);
                         if (foundType != null)
                         {
                             externalModule = foundType.EcmaModule;
@@ -356,7 +356,7 @@ namespace ILCompiler.IBC
                 }
                 else
                 {
-                    foundType = (EcmaType)externalModule.GetType(typeNamespace, typeName, throwIfNotFound: false);
+                    foundType = (EcmaType)externalModule.GetType(typeNamespace, typeName, NotFoundBehavior.ReturnNull);
                 }
 
                 if (foundType == null)
@@ -451,7 +451,7 @@ namespace ILCompiler.IBC
             {
                 if (EcmaModule.MetadataReader.GetTableRowCount(TableIndex.AssemblyRef) < index)
                     return null;
-                return EcmaModule.GetObject(MetadataTokens.EntityHandle(((int)CorTokenType.mdtAssemblyRef) | index)) as EcmaModule;
+                return EcmaModule.GetObject(MetadataTokens.EntityHandle(((int)CorTokenType.mdtAssemblyRef) | index), NotFoundBehavior.ReturnNull) as EcmaModule;
             }
         }
 
diff --git a/src/coreclr/tools/aot/ILCompiler.ReadyToRun/IBC/MIbcProfileParser.cs b/src/coreclr/tools/aot/ILCompiler.ReadyToRun/IBC/MIbcProfileParser.cs
index 987300df24b..22e54a8922a 100644
--- a/src/coreclr/tools/aot/ILCompiler.ReadyToRun/IBC/MIbcProfileParser.cs
+++ b/src/coreclr/tools/aot/ILCompiler.ReadyToRun/IBC/MIbcProfileParser.cs
@@ -41,7 +41,12 @@ namespace ILCompiler.IBC
                         // token type is 0, therefore it can't be a type
                         return new TypeSystemEntityOrUnknown((int)token);
                     }
-                    return new TypeSystemEntityOrUnknown((TypeDesc)_ilBody.GetObject((int)token));
+                    TypeDesc foundType = _ilBody.GetObject((int)token, NotFoundBehavior.ReturnNull) as TypeDesc;
+                    if (foundType == null)
+                    {
+                        return new TypeSystemEntityOrUnknown((int)token & 0x00FFFFFF);
+                    }
+                    return new TypeSystemEntityOrUnknown(foundType);
                 }
                 catch
                 {
@@ -265,7 +270,9 @@ namespace ILCompiler.IBC
                                 metadataObject = null;
                                 try
                                 {
-                                    metadataObject = ilBody.GetObject(token);
+                                    metadataObject = ilBody.GetObject(token, NotFoundBehavior.ReturnNull);
+                                    if (metadataObject == null)
+                                        metadataObject = metadataNotResolvable;
                                 }
                                 catch (TypeSystemException)
                                 {
@@ -509,7 +516,7 @@ namespace ILCompiler.IBC
                     throw new NotImplementedException();
                 }
 
-                public override MetadataType GetType(string nameSpace, string name, bool throwIfNotFound = true)
+                public override MetadataType GetType(string nameSpace, string name, NotFoundBehavior notFoundBehavior)
                 {
                     TypeSystemContext context = Context;
 
@@ -519,9 +526,14 @@ namespace ILCompiler.IBC
                         return Context.UniversalCanonType;
                     else
                     {
-                        if (throwIfNotFound)
+                        if (notFoundBehavior != NotFoundBehavior.ReturnNull)
                         {
-                            throw new TypeLoadException($"{nameSpace}.{name}");
+                            var failure = ResolutionFailure.GetTypeLoadResolutionFailure(nameSpace, name, "System.Private.Canon");
+                            ModuleDesc.GetTypeResolutionFailure = failure;
+                            if (notFoundBehavior == NotFoundBehavior.Throw)
+                                failure.Throw();
+
+                            return null;
                         }
                         return null;
                     }
diff --git a/src/coreclr/tools/aot/ILCompiler.TypeSystem.ReadyToRun/ILCompiler.TypeSystem.ReadyToRun.csproj b/src/coreclr/tools/aot/ILCompiler.TypeSystem.ReadyToRun/ILCompiler.TypeSystem.ReadyToRun.csproj
index c8e83d94bf8..580438dcc29 100644
--- a/src/coreclr/tools/aot/ILCompiler.TypeSystem.ReadyToRun/ILCompiler.TypeSystem.ReadyToRun.csproj
+++ b/src/coreclr/tools/aot/ILCompiler.TypeSystem.ReadyToRun/ILCompiler.TypeSystem.ReadyToRun.csproj
@@ -146,6 +146,12 @@
     <Compile Include="..\..\Common\TypeSystem\Common\ModuleDesc.cs">
       <Link>TypeSystem\Common\ModuleDesc.cs</Link>
     </Compile>
+    <Compile Include="..\..\Common\TypeSystem\Common\NotFoundBehavior.cs">
+      <Link>TypeSystem\Common\NotFoundBehavior.cs</Link>
+    </Compile>
+    <Compile Include="..\..\Common\TypeSystem\Common\ResolutionFailure.cs">
+      <Link>TypeSystem\Common\ResolutionFailure.cs</Link>
+    </Compile>
     <Compile Include="..\..\Common\TypeSystem\Common\TypeSystemEntity.cs">
       <Link>TypeSystem\Common\TypeSystemEntity.cs</Link>
     </Compile>