Speculative: Rust for base system components

[Brian Neal]

It was a debug build with no optimization for either compiler. But we 
can easily run a variety of settings for comparison:

Compiler              Flags                 Inst. Count Build Time
======================================================================
clang 7.0.0           none                           33 296ms
                       -O3                            23 341ms
rustc 1.31.0          none                          110 606ms
                       -C opt-level=3                 67 643ms
gcc 8.2               none                           37 211ms
                       -O2                            24 249ms
                       -O3                          119* 206ms

* With -O3, gcc unrolled and vectorized the loop. The other compilers 
did not emit vectorized code at any of the standard optimization levels.

So, essentially, double the build time and ~3 times the code for the 
same logic.

On 12/31/2018 7:23 PM, Garance A Drosehn wrote:
>
> On 31 Dec 2018, at 23:04, Brian Neal wrote:
>
>     This is a good read on some of the pitfalls of Rust:
>
>     https://hackernoon.com/why-im-dropping-rust-fd1c32986c88
>
>     In terms of performance, take a look at Rust on godbolt...a quick
>     test I just ran with a trivial program that sums up a sequence of
>     odd numbers is 29 instructions in C on clang 7.0 and a whopping
>     137 (!!!) on rustc 1.31.0!
>
>     Crazy...
>
> Did you compile your program as a "release build", or just as a
> standard (quick) build?
>
> --
> Garance Alistair Drosehn = drosih at rpi.edu
> Senior Systems Programmer or gad at FreeBSD.org
> Rensselaer Polytechnic Institute; Troy, NY; USA
>