[Sulik]

To me, the philosophy of C (and even C++ before things became nuts) is that you should be able to reasonably guess the assembly code resulting from the C code, the idea being that you can write assembly code with much less typing. These days, things seem to be moving in a more dogmatic direction with the underlying assumption that the vast majority of programmers are bad programmers.

[mhh__]

You're fighting a losing battle though. You can guess what shape the assembly looks like but ultimately unless you have measured and identified somewhere where you can make progress your brain simply cannot keep in mind all the little nuances of the optimizations a compiler does.

It's worth adding that the compilers themselves aren't perfect - you can use LLVM's code to try and predict how your loop will perform (LLVM-MCA) and last time I checked it wasn't amazingly accurate.

[Ar-Curunir]

That’s not true anyway today, because the assembly generated depends on the architecture, and there’s sufficient diversity there.

The only thing that you can predict about compiled C code is the instructions in the C abstract machine, because that’s what C targets.

[Sulik]

You can predict a pseudo-assembly output for a mental model of the architecture(s) you're targeting. It doesn't have to be an exact match, register allocation and all.