//
// Used to decide whether call or callvirt is needed
//
static bool IsVirtualCallRequired(Expression instance, MethodSpec method)
{
//
// There are 2 scenarious where we emit callvirt
//
// Case 1: A method is virtual and it's not used to call base
// Case 2: A method instance expression can be null. In this casen callvirt ensures
// correct NRE exception when the method is called
//
var decl_type = method.DeclaringType;
if (decl_type.IsStruct || decl_type.IsEnum)
{
return(false);
}
if (instance is BaseThis)
{
return(false);
}
//
// It's non-virtual and will never be null and it can be determined
// whether it's known value or reference type by verifier
//
if (!method.IsVirtual && Expression.IsNeverNull(instance) && !instance.Type.IsGenericParameter)
{
return(false);
}
return(true);
}
public void Emit(EmitContext ec, bool conditionalAccess)
{
Label NullOperatorLabel;
Nullable.Unwrap unwrap;
if (conditionalAccess && Expression.IsNeverNull(instance))
{
conditionalAccess = false;
}
if (conditionalAccess)
{
NullOperatorLabel = ec.DefineLabel();
unwrap = instance as Nullable.Unwrap;
}
else
{
NullOperatorLabel = new Label();
unwrap = null;
}
IMemoryLocation instance_address = null;
bool conditional_access_dup = false;
if (unwrap != null)
{
unwrap.Store(ec);
unwrap.EmitCheck(ec);
ec.Emit(OpCodes.Brtrue_S, NullOperatorLabel);
}
else
{
if (conditionalAccess && addressRequired)
{
//
// Don't allocate temp variable when instance load is cheap and load and load-address
// operate on same memory
//
instance_address = instance as VariableReference;
if (instance_address == null)
{
instance_address = instance as LocalTemporary;
}
if (instance_address == null)
{
EmitLoad(ec, false);
ec.Emit(OpCodes.Dup);
ec.EmitLoadFromPtr(instance.Type);
conditional_access_dup = true;
}
else
{
instance.Emit(ec);
}
}
else
{
EmitLoad(ec, !conditionalAccess);
if (conditionalAccess)
{
conditional_access_dup = !IsInexpensiveLoad();
if (conditional_access_dup)
{
ec.Emit(OpCodes.Dup);
}
}
}
if (conditionalAccess)
{
if (instance.Type.Kind == MemberKind.TypeParameter)
{
ec.Emit(OpCodes.Box, instance.Type);
}
ec.Emit(OpCodes.Brtrue_S, NullOperatorLabel);
if (conditional_access_dup)
{
ec.Emit(OpCodes.Pop);
}
}
}
if (conditionalAccess)
{
if (!ec.ConditionalAccess.Statement)
{
if (ec.ConditionalAccess.Type.IsNullableType)
{
Nullable.LiftedNull.Create(ec.ConditionalAccess.Type, Location.Null).Emit(ec);
}
else
{
ec.EmitNull();
}
}
ec.Emit(OpCodes.Br, ec.ConditionalAccess.EndLabel);
ec.MarkLabel(NullOperatorLabel);
if (instance_address != null)
{
instance_address.AddressOf(ec, AddressOp.Load);
}
else if (unwrap != null)
{
unwrap.Emit(ec);
var tmp = ec.GetTemporaryLocal(unwrap.Type);
ec.Emit(OpCodes.Stloc, tmp);
ec.Emit(OpCodes.Ldloca, tmp);
ec.FreeTemporaryLocal(tmp, unwrap.Type);
}
else if (!conditional_access_dup)
{
instance.Emit(ec);
}
}
}
public void Emit(EmitContext ec, bool conditionalAccess)
{
Label NullOperatorLabel;
Nullable.Unwrap unwrap;
if (conditionalAccess && Expression.IsNeverNull(instance))
{
conditionalAccess = false;
}
if (conditionalAccess)
{
NullOperatorLabel = ec.DefineLabel();
unwrap = instance as Nullable.Unwrap;
}
else
{
NullOperatorLabel = new Label();
unwrap = null;
}
if (unwrap != null)
{
unwrap.Store(ec);
unwrap.EmitCheck(ec);
ec.Emit(OpCodes.Brtrue_S, NullOperatorLabel);
}
else
{
EmitLoad(ec);
if (conditionalAccess)
{
ec.Emit(OpCodes.Dup);
ec.Emit(OpCodes.Brtrue_S, NullOperatorLabel);
ec.Emit(OpCodes.Pop);
}
}
if (conditionalAccess)
{
if (!ec.ConditionalAccess.Statement)
{
if (ec.ConditionalAccess.Type.IsNullableType)
{
Nullable.LiftedNull.Create(ec.ConditionalAccess.Type, Location.Null).Emit(ec);
}
else
{
ec.EmitNull();
}
}
ec.Emit(OpCodes.Br, ec.ConditionalAccess.EndLabel);
ec.MarkLabel(NullOperatorLabel);
if (unwrap != null)
{
unwrap.Emit(ec);
var tmp = ec.GetTemporaryLocal(unwrap.Type);
ec.Emit(OpCodes.Stloc, tmp);
ec.Emit(OpCodes.Ldloca, tmp);
ec.FreeTemporaryLocal(tmp, unwrap.Type);
}
}
}
