D for safety critical applications

Gregor Mückl gregormueckl at gmx.de
Tue Feb 9 17:11:48 UTC 2021

On Tuesday, 9 February 2021 at 14:54:35 UTC, IGotD- wrote:
> On Tuesday, 9 February 2021 at 13:35:36 UTC, Gregor Mückl wrote:
>> There is a fair amount of hate in this post that I can't agree 
>> with.
> Then you have a crewed up idea what hate means. Hate does not 
> mean that you disagree with someone.

Please allow me to retract the part mentioning hate. That may 
have gone too far. I'm sorry if I offended you.

>> I've worked with certified compilers, too. It was mainly one 
>> of the major products in the field. The package was a mixed 
>> bag. The custom IDE is lacking and the proprietary build tools 
>> are not very good, but the actual compiler for our target 
>> platform turned out to be very good. We threw it at a pretty 
>> big preexisting codebase and it worked (we had a few places 
>> where we were relying on subtle UB - that's on us). Compared 
>> to GCC, the generated code would consistently be smaller and 
>> thus faster, even when I compared unoptimized builds to GCC 
>> with optimizations (curiously, speed optimized GCC output was 
>> smaller than size optimized output!).
> The main reason some company uses a certain "certified" 
> compiler is because the customer demands it. There in between 
> anything is possible with any kind of back room deal. Just like 
> doctors get money under the table in order to promote a certain 
> drug, which we know is commonplace.

This is not representative of all industries everywhere. My own 
personal experience showed  me that there are places where this 
is taken seriously for good reasons. It seems that you and I have 
made very different experiences during our careers. Nothing wrong 
with that, I guess.

> The compiler I have worked with had a number of bugs and then I 
> tried GCC and of course it ran perfectly with better code 
> generation. The answer is of course obvious GCC is used by the 
> hundreds of thousands and many contributing to the compiler. 
> This compared to a small company creating some "certified" 
> compiler. I'm all of commercial SW but I cannot deny that the 
> huge backing of the GCC compilers is hard to beat. If I would 
> decide which compiler to use I would of course go with GCC and 
> skip the certified compiler, however it is the customers that 
> dictates what to use.

In my experience, the quality of GCC code generation varies a lot 
depending on the target platform. It's an extremely good compiler 
for desktop/server class CPUs, but in my experience, it doesn't 
target small embedded platforms very well. This low end seems to 
be too niche to attract many developers to GCC or LLVM.

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