[Info-vax] LLVM, volatile and async VMS I/O and system calls

[chris]

On 09/25/21 19:46, Simon Clubley wrote:
> On 2021-09-25, chris<chris-nospam at tridac.net>  wrote:
>>
>> We are probably in agreement, just different interpretations of
>> the same thing ?. One thing I always do when confronted with a new
>> compiler or tool chain is to look at the assembler source output
>> to make sure it's doing what I expect it to. Don't bother once
>> i'm happy with the compiler, but it does help to get to know what
>> the compiler is doing under various conditions. It's also useful
>> if you are trying to optimise performance. For example, trying to
>> decide which loop construct to use for / next, or do / while. Quite
>> important in the old 8 bit days, but moderm micros are so good
>> now, it's less of an issue. Quite often a single line of asm
>> per C statement, but you can fine tune the programming style to'
>> get the best results form the compiler....
>>
>
> :-)
>
> Looking at the generated code has proved interesting at times. :-)
>
> The following Ada Issue is a direct result of me looking at someone's
> problem on comp.lang.ada a number of years ago which was caused by
> the code the Ada compiler had generated:
>
> http://www.ada-auth.org/cgi-bin/cvsweb.cgi/ai12s/ai12-0128-1.txt?rev=1.15&raw=N
>
> The following AI is also directly related to this:
>
> http://www.ada-auth.org/cgi-bin/cvsweb.cgi/ai12s/ai12-0127-1.txt?rev=1.27&raw=N
>
> [I am _not_ a member of the ARG or anything like that. I am just a
> normal programmer who includes Ada in the list of languages I know.]
>
> Simon.
>

Interesting examples, but just how much of that was due to system
complexity ?.

I bought a couple of books on ada some years ago, but have never
worked with it. One of the problems I have with some tools and
languages is the lack of transparency through the whole chain.
For some of the projects worked on here and for me to be able to
be fully confident about the end result, I need to have complete
transparency from source file right down to the hardware. Anything
that might hide detais or tools that prevent that would be unusable.

Some things are just too clever for their own good, and don't care
how thoroughly they have been tested :-)...

Chris