folly::is_register_pass_v

template<typename T>
constexpr bool is_register_pass_v = (sizeof(T) <= register_pass_max_size) && std::is_trivially_copyable_v<T>;

Description

Whether a value may be passed in a register.

Trivially-copyable values up to register_pass_max_size in width may be passed by-value in registers rather than implicitly by-reference to stack copies.

Approximate. Accuracy is not promised.