presto-main/src/main/java/io/prestosql/sql/gen/BytecodeGeneratorContext.java/BytecodeGeneratorContext/generateCall
class BytecodeGeneratorContext:    public BytecodeNode generateCall(String name, ScalarFunctionImplementation function, List<BytecodeNode> arguments)
    {
        Optional<BytecodeNode> instance = Optional.empty();
        if (function.getInstanceFactory().isPresent()) {
            FieldDefinition field = cachedInstanceBinder.getCachedInstance(function.getInstanceFactory().get());
            instance = Optional.of(scope.getThis().getField(field));
        }
        return generateInvocation(scope, name, function, instance, arguments, callSiteBinder);
    }