Speculative: Rust for base system components

[Alan Somers]

On Sun, Jan 6, 2019 at 10:49 AM Igor Mozolevsky <igor at hybrid-lab.co.uk> wrote:
>
> On Sun, 6 Jan 2019 at 16:58, Brian Neal <brian at aceshardware.com> wrote:
>
> > I don't have it anymore, but yours is close enough.  When compiling your
> > first example, I get 156 instructions, including map iterators and rust
> > result assert/unwrap logic.  Your second example produces 21 lines,
> > including a loop iterator:
>
> <snip>
>
> All of *nine* instructions in C including (a) constant running time,
> i. e. O(1) cf. O(c), and (b) integer wrapping check-signal:-
>
> #include<stdint.h>
>
> int32_t oddcount(int32_t c) {
>   const int32_t max_c = 92679; /* sqrt(INT32_MAX)*2-1 */
>   return((c > max_c) ? 0: ((c + 1) / 2) * ((c + 1) / 2));
> }
>
> oddcount:
>   xor eax, eax
>   cmp edi, 92679
>   jg .L1
>   lea eax, [rdi+1]
>   mov ecx, 2
>   cdq
>   idiv ecx
>   imul eax, eax
> .L1:
>   ret
>
> Like I said, no matter what tool one uses, bugs are easy to introduce
> (yes, even in Rust!), wrapping ints in the instant case...
>
>
>
>
> --
> Igor M.

Igor, please stop commenting unless you have something constructive to add.