[FIXED] why passing string_view by value is faster than const reference

Issue

I checked this question, and most answers say that I should pass it by value despite it's clearly passing more data (since by value you pass 8 bytes while by reference only 4 bytes, in 32bit system sizeof(string_view) > sizeof(string_view*)) is that still relevant in C++20/17 ? and can someone explains why exactly ?

Solution

Indirection through a reference (as well as a pointer) has a cost. That cost can be more than the cost of copying a few bytes. As in most cases, you need to verify through measurement whether that is true for your use case / target system. Note that if the function is expanded inline, then there is unlikely to be any difference as you may end up with identical assembly in either case. Even if not, the difference may be extremely small and hard to measure.

Answered By - eerorika

Answer Checked By - David Goodson (PHPFixing Volunteer)