public static void LoadFunction(JavaCode code, Mono.Cecil.Cil.Instruction cilInst)
{
if (cilInst.Operand is MethodReference implMethodRef)
{
var implMethod = CilMethod.From(implMethodRef);
var(declType, declMethod, dlgMethodName) = FindInterfaceType(cilInst);
if (dlgMethodName != null)
{
// if this is an artificial delegate for a functional interface,
// then we can't actually instantiate this particular delegate,
// because its definition only exists in the DLL created by
// DotNetImporter; see BuildDelegate there. we fix the Newobj
// instruction to instantiate system.FunctionalInterfaceDelegate.
cilInst.Next.Operand = DelegateConstructor(cilInst.Next.Operand);
declMethod = new JavaMethodRef(dlgMethodName,
implMethod.ReturnType,
implMethod.Parameters);
}
if (IsPrimitive(declMethod.ReturnType))
{
// primitive return value is translated to java.lang.Object,
// because the delegate target may return a generic type that
// is specialized for the primitive type in the delegate.
// see also MakeInterface and GenerateInvoke
declMethod = new JavaMethodRef(
declMethod.Name, JavaType.ObjectType, declMethod.Parameters);
}
// select the method handle kind for the dynamic call site.
// for a non-static invocation, we need to push an object reference.
JavaMethodHandle.HandleKind callKind;
if (implMethod.DeclType.IsInterface)
{
callKind = JavaMethodHandle.HandleKind.InvokeInterface;
}
else
{
callKind = JavaMethodHandle.HandleKind.InvokeVirtual;
}
if (cilInst.OpCode.Code == Code.Ldftn)
{
if (implMethod.IsStatic)
{
callKind = JavaMethodHandle.HandleKind.InvokeStatic;
}
else
{
var implMethodDef = CilMethod.AsDefinition(implMethodRef);
bool isVirtual = implMethodDef.IsVirtual;
if (isVirtual && implMethodDef.DeclaringType.IsSealed)
{
isVirtual = false;
}
if (!isVirtual)
{
// non-virtual instance method
code.NewInstruction(0x59 /* dup */, null, null);
code.StackMap.PushStack(JavaType.ObjectType);
}
else
{
// virtual method should only be specified in 'ldvirtftn'
throw new Exception("virtual method referenced");
}
}
}
//
// the method may take generic type parameters, i.e. the System.Type
// parameters that are added at the end of the parameter list, by
// CilMethod::ImportGenericParameters. but when the delegate is
// called, these parameters will not be pushed. therefore we do
// the following when assigning such a method to a delegate:
//
// (1) we select a different implementing method, i.e. the bridge
// method generated by CreateCapturingBridgeMethod (see below),
// which moves the type arguments to the head of the parameter list.
// (2) we generate and push the type arguments at this time, via
// calls to GenericUtil.LoadGeneric.
// (3) we specify the type arguments as capture parameters of the
// call site. (see also JavaCallSite.) this means the generated
// proxy will inject these parameters when it calls the bridge
// method from step (1), and that bridge method will push these
// parameters at the end of the parameter list, when it invokes
// the actual target method.
//
List <JavaFieldRef> TypeArgs = null;
JavaMethodRef implMethod2 = implMethod;
var implGenericMethod = implMethod.WithGenericParameters;
if (implGenericMethod != implMethod)
{
implMethod2 = new JavaMethodRef(
"delegate-bridge-" + implGenericMethod.Name,
implMethod.ReturnType, implMethod.Parameters);
var count1 = implMethod.Parameters.Count;
var count2 = implGenericMethod.Parameters.Count;
TypeArgs = implGenericMethod.Parameters.GetRange(count1, count2 - count1);
var callMethod = CilMain.GenericStack.EnterMethod(implMethodRef);
for (int i = count1; i < count2; i++)
{
GenericUtil.LoadGeneric(implGenericMethod.Parameters[i].Name, code);
}
for (int i = count1; i < count2; i++)
{
code.StackMap.PopStack(CilMain.Where);
}
}
// create a CallSite that implements the method signature
// declMethod, in the functional interface declType, in order
// to proxy-invoke the method implMethod.DeclType::implMethod.
var callSite = new JavaCallSite(declType, declMethod,
implMethod.DeclType, implMethod2,
TypeArgs, callKind);
code.NewInstruction(0xBA /* invokedynamic */, null, callSite);
if (callKind != JavaMethodHandle.HandleKind.InvokeStatic)
{
code.StackMap.PopStack(CilMain.Where);
}
code.StackMap.PushStack(CilType.From(declType));
}
else
{
throw new InvalidProgramException();
}
//
// ldftn or ldvirtftn should be followed by newobj, which we can use
// to identify the delegate, and therefore, the interface
//
(JavaType, JavaMethodRef, string) FindInterfaceType(
Mono.Cecil.Cil.Instruction cilInst)
{
cilInst = cilInst.Next;
if (cilInst != null && cilInst.OpCode.Code == Code.Newobj &&
cilInst.Operand is MethodReference constructorRef)
{
var dlgType = CilType.From(constructorRef.DeclaringType);
if (dlgType.IsDelegate)
{
//
// check for an artificial delegate, generated to represent a
// java functional interface: (BuildDelegate in DotNetImporter)
//
// delegate type is marked [java.lang.attr.AsInterface],
// and is child of an interface type.
// interface type is marked [java.lang.attr.RetainName],
// and has one method.
//
var dlgType0 = CilType.AsDefinition(constructorRef.DeclaringType);
if (dlgType0.HasCustomAttribute("AsInterface"))
{
var ifcType0 = dlgType0.DeclaringType;
var ifcType = CilType.From(ifcType0);
if (ifcType.IsInterface && ifcType.IsRetainName &&
ifcType0.HasMethods && ifcType0.Methods.Count == 1)
{
return(ifcType, null, ifcType0.Methods[0].Name);
}
}
//
// otherwise, a normal delegate, which may be generic, or plain.
// interface name is DelegateType$interface.
// we look for a method named Invoke.
//
foreach (var method in dlgType0.Methods)
{
if (method.Name == "Invoke")
{
return(InterfaceType(dlgType), CilMethod.From(method), null);
}
}
}
}
throw new InvalidProgramException();
}
//
// create a method reference to delegate constructor from baselib:
// system.MulticastDelegate::.ctor(object, object)
//
CilMethod DelegateConstructor(object Operand)
{
var baseType = CilType.AsDefinition(((MethodReference)Operand)
.DeclaringType).BaseType;
if (baseType.Namespace != "System" || baseType.Name != "MulticastDelegate")
{
throw CilMain.Where.Exception(
$"delegate base type is '{baseType.Name}', "
+ "but expected 'System.MulticastDelegate'");
}
return(CilMethod.CreateDelegateConstructor());
}
}
