I've said it before - leveraging "restrict" is far from trivial.
In practice, what you do is look at the assembly of your inner loops, scratch your head, and try putting "restrict" in various places that seem like they'd make sense, and then look at the assembly of your inner loop. Which requires building a mental model of what the assembly of your inner loops ought to look like, and then actually looking at it, and then running it to see if your idea of what the assembly out to look like was actually a good one.
If your expertise is in numerical methods first and assembly-level optimization second (or, like, nth), Fortran can save you a lot of ballache.
In practice, what you do is look at the assembly of your inner loops, scratch your head, and try putting "restrict" in various places that seem like they'd make sense, and then look at the assembly of your inner loop. Which requires building a mental model of what the assembly of your inner loops ought to look like, and then actually looking at it, and then running it to see if your idea of what the assembly out to look like was actually a good one.
If your expertise is in numerical methods first and assembly-level optimization second (or, like, nth), Fortran can save you a lot of ballache.