How to better parallelize GHC build.

[Karel Gardas]

Hi Neil,

On 03/ 8/15 02:58 PM, Neil Mitchell wrote:
> Hi Karel,
>
>> I am. Is this agreed way among the GHC developers? I was not sure so I
>> mentioned shake just lightly...
>
> It's certainly agreed to give it a go, and implementation work is
> ongoing. If it works better than the existing system then I suspect
> we'll switch. I certainly hope to get full parallelism, although I
> don't have as many core as you do to test!

I've investigated for short time stage1 dependencies and what make does 
with them and so far had not found any issue which may be fixed by hand 
added dependency into the makefile build system.

For example one of the biggest issue in stage1 is excessive dependency 
on DynFlags at least. Anyway, I'll see what shake/ghc brings to the 
table -- perhaps I've not looked that well and there is a way to solve 
that... Anyway, idea of separate compilation of interface files still 
comes to my head as a nice experiment to do.

Thanks,
Karel