[OT] The Usual Arithmetic Confusions

[Elronnd]

On Friday, 4 February 2022 at 21:13:10 UTC, Walter Bright wrote:
> It's slower, too.

Not anymore.  And div can be faster on smaller integers.


> You're paying a 3 size byte penalty for using short arithmetic 
> rather than int arithmetic.

1. You are very careful to demonstrate short arithmetic, not byte 
arithmetic, which is the same size as int arithmetic on x86.

2. Cycle-counting (or byte-counting) is not a sensible approach 
to language design.  It is relevant to language implementation, 
maybe; and whole-program performance may be relevant to language 
design; but these sorts of changes are marginal and should not 
get in the way of correct semantics.

3. Your code example actually does exactly what you 
suggest--using short arithmetic for storage.  It just happens 
that in this case using short calculations rather than int 
calculations yields the same result and smaller code.

4. (continued from 3) in a larger, more interesting expression, 
regardless of language semantics, the compiler will generally be 
free to use ints for intermediates.