> Since the address of arr is statically known [...]
No, that's almost never the case – only when accessing a static array. Typically, that restricts it to static look-up tables and very simple embedded systems.
No, that's almost never the case – only when accessing a static array. Typically, that restricts it to static look-up tables and very simple embedded systems.
That's what I was thinking, too, but most of the time (even if the index is not static) the -1 can be eliminated by just modifying the address at which the array is assumed to start. That is,
compiles into an access at address Since the address of arr is statically known, arr - 1 is, too, and the address of "one before the first element" will be what's written as the base for the memory access.