Faster linker

[H. S. Teoh]

On Fri, Nov 09, 2018 at 01:04:51AM +0000, bennygui via Digitalmars-d wrote:
> Hi,
> 
> I am compiling a small vibe.d project with dmd via dub. The linker
> takes most of the time when invoking "dub build" (total: 11 seconds).
> I've tried compiling with gdc and it's the same (11 seconds). With
> ldc, it's faster (6 seconds).
> 
> I did not time anything except "dub build" but I get the feeling that
> dmd compiles much faster but is slowed down by the linker and that ldc
> takes longer to compile but has a faster linker.
> 
> Is there any way to get faster link time? I'm on Linux (Gentoo).
[...]

Are you sure it's the linker, and not the compiler, or dub itself?

If it's the linker, then you could look into using gold instead of the
BFD linker.

I suspect most of your build time is spent in dub, though.  You could
try various options to turn off network access and dependency resolution
when running dub, which should improve total running time. (Of course,
you need to run it at least once without those options so that it pulls
in required dependencies, but once those are downloaded, there's no need
to check dependencies every single time.)  You could also ditch dub and
use your own build system, by creating an empty dummy project in a
subdirectory and running dub once to pull in your dependencies, then
link to the artifacts yourself directly. (I did that in one of my own
projects, and it sped up build time by an order of magnitude.)

Another possible cause is that Diet templates are very template- and
CTFE-heavy, and will often soak up gobs of RAM and CPU every time they
are compiled.  A possible solution is to separate out the Diet templates
into their own source files, and use separate compilation to avoid
rebuilding those files unless there was an actual change in the Diet
code. (I've also run into this in my vibe.d project. I'm considering to
replace Diet templates with something lighter-weight, but haven't taken
that step yet.)


T

-- 
It is the quality rather than the quantity that matters. -- Lucius Annaeus Seneca