Linker speed on GHC

Ben Gamari ben at
Sat Dec 22 16:39:57 UTC 2018

Ben Gamari <ben at> writes:

> Hi Tamar,
> I have recently been looking quite a bit at our continuous integration
> due to the transition to GitLab and have found that the Windows builder
> is almost always the rate-limiting step. Builds routinely take three
> hours or more, with much of the time being spent in the bfd linker.
> I am working to add more builders but ultimately there is only so much
> that we can do with the resources we have, especially given that Windows
> VM instances are essentially twice the cost of their Linux counterparts
> due to Windows licensing fees.
> I know in the past you have thought about ld performance on Windows. Has
> there been any development on this front? Is there anything obvious we
> can do to improve the situation?
I have done a bit of investigation and it looks like GCC 9 will ship
with `-fuse-ld=lld` support. Phyx, I seem to recall that you have tried
LLD on Windows in the past. Do you recall how that went?

Anyways, I have opened a GHC ticket to track this issue (#16084).


- Ben

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