Rust seems to bring some love to Rpi

[jahboater]

Interesting.

(I noticed that although doing / 8 was just as fast as >> 3 on my laptop, on the RPi it was slower so I switched it back)

I think any modern compiler should do that by the way. In my code, rustc converted / 2 to "asr r6, r0, #1" successfully.

[paddyg]

Yes, not sure why. It's a small but real difference (0.950s c.f. 0.925s) I've not looked at the internals of the generated code.

Doing a basic prime calculation like the subject of this discussion, I get

laptop (to 100,000)
2.35s +/-0.06 C
2.31s +/-0.01 rust
RPi3 (to 50,000)
8.01s +/-0.07 C
11.4s +/-0.10 rust

So 50% slower rather than 10x slower.

[jahboater]

Rustc uses LLVM (as Clang does) which is quite respectable, and should produce fast code.
I would certainly expect it to be in the same ball park as C.

The silly program I used did "if( n % d == 0 )" in a tight inner loop .....
the ARMv6 code produced by rustc/LLVM was:

bl __aeabi_idivmod

The much faster ARMv8 code produced by GCC was:

sdiv r1, r4, r3
mls r1, r3, r1, r4

which explains the 10x performance difference (never use trivial artificial benchmarks!)

[Heater]

paddyg,

Sounds like an expanded version of the Raspberry Pi forum rules "Be good to each other"... But it doesn't say you can't use rust for whatever devilish antisocial purpose you had in mind, just abide by the rules if you contribute to IRC channels, github or official rust.org forum. So you could use rust and be as unfriendly as you want on reddit (so long as you don't harass people).

I don't particularly have a desire to use Rust or any other programming language for "devilish antisocial purposes". Neither do I want to be unfriendly to anyone on reddit or anywhere else.

I do find the Rust code of conduct distasteful. Basically it says that if you ever express an opinion that someone finds "uncomfortable" then you should apologize and/or be ostracized.

Well, how could I ever use Rust? Perhaps I might want to file a bug report? It would be impossible to know if I had overstepped someones comfort zone? My disdain of Political Correctness might be detected almost immediately.

This is the kind of thinking that deposed Brendan Eich, the inventor of Javascript, from his position at a company he helped build. Simply for having a political view that others disagreed with. http://www.bbc.com/news/technology-26868536

It's the kind of thinking that got Douglas Crockford uninvited from giving a key note speech at a conference because his use of words like "promiscuous" in a technical sense made somebody feel uncomfortable. http://atom-morgan.github.io/in-defense ... -crockford

It's the kind of thinking that got James Damore fired from Google this summer: https://www.washingtonpost.com/news/mor ... 6fed795710

As a language Rust might be fine.

I find it a bit dishonest for rust-lang.org to describe Rust as a "systems programming language". As far as I can tell Rust cannot compile itself yet. You cannot build a Rust compiler using a Rust compiler. It depends on LLVM. That is to say C++.

Maybe one day.

[mifwoo]

I find it a bit dishonest for rust-lang.org to describe Rust as a "systems programming language". As far as I can tell Rust cannot compile itself yet. You cannot build a Rust compiler using a Rust compiler. It depends on LLVM. That is to say C++.

Maybe one day.

Rust compiles itself since 2011.

The same year, work shifted from the initial compiler (written in OCaml) to the self-hosting compiler written in Rust.[30] Known as rustc, it successfully compiled itself in 2011.

[Heater]

That's not quite true now is it mifwoo.

Yes Rust compiles itself but it generates an intermediate representation of the code, LLVM IR.

One then needs LLVM to optimize and generate code from that intermediate representation. LLVM is written in C++.

So, if you want to build a complete Rust tool chain from scratch you need a working Rust compiler and a working C++ compiler.

https://www.quora.com/Is-Rust-a-self-hosted-language

[ejolson]

That's not quite true now is it mifwoo.

Yes Rust compiles itself but it generates an intermediate representation of the code, LLVM IR.

One then needs LLVM to optimize and generate code from that intermediate representation. LLVM is written in C++.

So, if you want to build a complete Rust tool chain from scratch you need a working Rust compiler and a working C++ compiler.

https://www.quora.com/Is-Rust-a-self-hosted-language

I think Rust being a systems programming language refers to the feature set which allows writing low-level code such as device drivers and memory managers which interact directly with the hardware.

If you want a self-hosting system based on Rust, which is a different thing in my opinion, the easiest way might be to first write a C compiler in Rust. Use the Rust-built C compiler to compile a C++ compiler, then use the C++ compiler to compile LLVM.

[Heater]

ejolson,

I think Rust being a systems programming language refers to the feature set which allows writing low-level code such as device drivers and memory managers which interact directly with the hardware.

That is the way I read it as well.

There is even an entire operating system written in Rust to prove the point: https://github.com/redox-os/redox

Although, as far as I can tell, Redox does not run on bare hardware yet.

If you want a self-hosting system based on Rust, which is a different thing in my opinion, ...

I think that was my point. As it stands you cannot build a Rust only self hosting system, on Redox for example. You would have to get a C++ compiler running on Redox first.

the easiest way might be to first write a C compiler in Rust. Use the Rust-built C compiler to compile a C++ compiler, then use the C++ compiler to compile LLVM.

That all sounds far to tortuous.

Somebody did suggest recreating LLVM in Rust. That would do it. I don't think anyone is ever going to do that. But who knows? There are crazy people out there!

[paddyg]

The arguments for rust are that it's 'easier' to write 'safe' code. The problem is that if the switch is from old C and C++ utilities, not only is the switch from code that's already been written (so requires zero effort to write) and has a large pool of potential maintainers, but it's been very extensively tested in the real world. As you say it seems an extravagant task - but it would be very good training so maybe it will happen eventually.

[Heater]

I think, the best bet is that Rust or whatever new language the youngn's come up with next can make use of all the existing infrastructure. That is interface and link with C easily. I have no idea if Rust can do that but I presume so.

On the other hand, this last week I have found that openssl in Debian Linux, hence Raspbian, suffers from memory leaks and race conditions. Our whole foundations are rotten.

[Paeryn]

I think, the best bet is that Rust or whatever new language the youngn's come up with next can make use of all the existing infrastructure. That is interface and link with C easily. I have no idea if Rust can do that but I presume so.

Yes, Rust has a decent FFI so you can call C code from Rust and vice versa without too much hassle. It's quite a nice language.

[Gavinmc42]

What lib does Redox use re openssh/ssl?

https://www.redox-os.org/
I am hanging out waiting to try Redox on a Pi3 in Aarch64.

I was impressed on how easy it was to get Rustc working on a Pi and the language itself is too not bad.
Probably one of the nicer ones of this new gen.
And the Servo browser has some nice tricks.

Throw everything out and run Redox on RISCV?
Redox on Pi3 with simple Servo browser, I can see myself using it.
Might have to try it on a x86 box first, yuk.

[jahboater]

Yes, Rust has a decent FFI so you can call C code from Rust and vice versa without too much hassle. It's quite a nice language.

People could also look at "go" and "D".
Probably all inspired by the excessive complexity of modern C++.

[Heater]

Looking at the Redox cookbook we see they have a lot of recipes for making use of C libraries and programs in Redox. Like this one for openssh: https://github.com/redox-os/cookbook/pu ... 0a75884b85

Openssl for rust is here: https://github.com/sfackler/rust-openssl Which we see depends on openssl in C, OpenSSL version 1.0.1 or above, or LibreSSL.

[Gavinmc42]

IoT not going to take off until we get secure comms.
Reusing old code with who knows what inside?

[jamesh]

IoT not going to take off until we get secure comms.
Reusing old code with who knows what inside?

We have secure comms, the IoT suppliers just need to use it....and some of course do.

[Heater]

Gavinmc42,

Reusing old code with who knows what inside?

We know exactly what's inside openssl. Here it is:
https://github.com/openssl/openssl

Arguably it's better to fix what we have if need be rather than create a whole new version with a whole lot of new issues of it's own.

I was subjecting my C++ to analysis with the memory leak and thread analyzers that come the clang/llvm C++ compiler. I found a couple of memory leaks and thread race conditions in openssl. So far I'm not sure if these issues are down to openssl itself or the way it is used by the pqxx postgress database connector I'm using. We shall see.

Then again secure comms as provided by openssl is not the end of the story. An awful lot of systems get broken for many other reasons than the crypto library they are using. This security thing is hard.