If I had the source code, yes .. but this is not the case here .. so there is no way, like .. from the exe properties or other differences.
Because I hoped the game wasn't using it, so there would be a lot of room for improvement if I made something similar.
You mean like, to know if you can make a similar game and have it run better?
Because if so, this is kind of irrelevant.
There's more or less seven hundred billion things more important to optimization than whatever compiler you use.
Coding habits. Objects. Draw calls. Texture swaps. Collisions. Data Structures. Shaders. Surfaces. Physics. AI. Literally everything can be affected by your execution and there's always,
always room for improvement. The compiler helps, but it's not magic. A badly coded game with YYC that handles everything poorly will likely still run worse than a super optimized VM version of the same game with super efficient solutions for every programming problem.
YYC won't affect every project the same anyway. Some games run like 10x as fast. My game goes from 800 fps to... Maybe somewhere over 1000 the last time I tested it?