[fpc-devel] New less verbose compilation of trunk

[Henry Vermaak]

On 07/03/12 12:02, Marco van de Voort wrote:
> In our previous episode, Henry Vermaak said:
>>>> PS:
>>>> Adding any more (if possible) parallel compilation support would be
>>>> awesome too. This already saves me over 1 minute in compile time on my
>>>> quad core. Yes, I hate it if CPU's just sit idle.
>>>
>>> IIRC add  FPMAKEOPT='-T 3'   (3= number of paralel threads)
>>
>> This makes a big difference for me:
>>
>> Without FPCMAKEOPT: 1m48.056s
>> With FPCMAKEOPT="-T 9": 1m13.833s
>>
>> Unfortunately, cycling the compiler is taking really long and -j 9 isn't
>> helping much (or at all).
>
> fpmake only handles packages/.
>
> fpmake (or make -j the way FPC used it in the past) can't really speed up
> runs that are a single compiler invocation (like the compiler), unless it
> can run two such runs in paralel.
>
> In packages this is possible, in the compiler cycle compiler depends on RTL,
> and the "next" rtl depends on the "previous" compiler, so nothing can be
> done there.
>
> To exploit paralellism in single compiler invocations, threading should be
> brought into the compiler, but that is an huge and uncertain job.

With c, the compilation of .c -> .o  is isolated, so many of them can be 
run in parallel, which means that compiling e.g. the linux kernel, you 
get great performance from make -j %d.  Is it possible to have fpc do 
the same thing somehow?  Bringing threading into the compiler sounds 
very scary, indeed.

Henry