[fpc-pascal] Compile time -> processor benchmark values

[Michael Van Canneyt]

On Mon, 29 May 2023, Hairy Pixels via fpc-pascal wrote:

>
>
>> On May 29, 2023, at 9:24 PM, Sven Barth via fpc-pascal <fpc-pascal at lists.freepascal.org> wrote:
>>
>> FPC itself is single threaded. So for that the single thread rating is more important. However Lazarus (and fpmake) can parallelize the building of packages if they don't depend on each other. On the other hand this is only really important when rebuilding and not when doing normal builds.
>
> I was curious about this, if the compiler was overhauled and it could be
> made multi-threaded could it compile each unit on a different thread? 
> Maybe it would be complicated but if a unit graph was constructed   you
> could isolate units that don't depend on each other and compile them on
> their own threads right?

Theoretically, yes.

But there are some global structures that would need to be protected from
simultaneous access by the various threads (e.g. symbol tables).

It is far from sure this can be done in a manner that does not destroy 
the advantage of multi-thread. It could well be that the threads spend more
time waiting than actually compiling.

>
> If I recall this is impossible currently because of the use of global variables.

Yes. There are lots of them.

Michael.