Show HN: Single-Header Profiler for C++17

I often found myself wondering "how much does this code segment take in terms of total runtime" and it's often quite annoying to figure out with optimizations enabled, especially when working on something new or testing someone else's implementation without the proper tooling set up. Wanted to have a single include lib that would allow us to write something like:

``` PROFILE("Loop 1") for (...) // some work ```

and have the next expression automatically record time & dump results to a table. Wrote a few macros to do exactly that a few months back, but they were primitive and basically unusable for recursive code.

Tried to come up with a more generic solution that would build a call graph for nested profiler-macros, handle threads and etc. but doing so in a naive way would be super slow since we'd need some kind of a recursive map of nodes with callsites as a keys.

Recently had a revelation that it is possible to use macro-generated thread_local's to associate callsites with integer IDs on the fly and with some effort call graph can be neatly encoded in a few contiguous arrays with all graph building & traversal logic reduced to simple checks and array lookups. Realized threading can be quite easily supported too in an almost lock-free fashion.

After a few days of effort ended up building what I believe is a very much usable single-header profiling lib. Couldn't find anything quite like it, so I'd like to present it here and hear some opinions on the product:

https://github.com/DmitriBogdanov/UTL/blob/master/docs/modul...