Macro performance_hints 

macro_rules! performance_hints {
    ($function_name:expr, {
        $(complexity: $complexity:expr,)?
        $(simdfriendly: $simd:expr,)?
        $(parallelizable: $parallel:expr,)?
        $(gpufriendly: $gpu:expr,)?
        $(memorypattern: $memory:expr,)?
        $(cachebehavior: $cache:expr,)?
        $(iopattern: $io:expr,)?
        $(optimizationlevel: $opt:expr,)?
        $(expectedduration: $duration:expr,)?
        $(memoryrequirements: $mem:expr,)?
        $(customhints: {$($key:expr => $value:expr),*$(,)?})?
    }) => { ... };
}

Macro to create and register performance hints in one step