Profiling DMD's Compilation Time with dmdprof

[Manu]

On Thu, Nov 8, 2018 at 12:10 AM Joakim via Digitalmars-d-announce
<digitalmars-d-announce at puremagic.com> wrote:
>
> On Thursday, 8 November 2018 at 07:54:56 UTC, Manu wrote:
> > On Wed, Nov 7, 2018 at 10:30 PM Vladimir Panteleev via
> > Digitalmars-d-announce <digitalmars-d-announce at puremagic.com>
> > wrote:
> >>
> >> On Thursday, 8 November 2018 at 06:08:20 UTC, Vladimir
> >> Panteleev wrote:
> >> > It was definitely about 4 seconds not too long ago, a few
> >> > years at most.
> >>
> >> No, it's still 4 seconds.
> >>
> >> digger --offline --config-file=/dev/null -j auto -c
> >> local.cache=none build     7.31s user 1.51s system 203% cpu
> >> 4.340 total
> >>
> >> > It does seem to take more time now; I wonder why.
> >>
> >> If it takes longer, then it's probably because it's being
> >> built in one CPU core, or in the release build.
> >
> > https://youtu.be/msWuRlD3zy0
>
> Lol, I saw that link and figured it was either some comedy video,
> like the Python ones Walter sometimes posts, or you were actually
> showing us how long it takes. Pretty funny to see the latter.

It's not so funny when every one-line tweak burns 2 minutes of my life away.

> > DMD only builds with one core, since it builds altogether.
>
> Yes, but your build time is unusually long even with one core.
> Are the D backend and frontend at least built in parallel to each
> other?

That doesn't matter, you can clearly see the backend built in less
than 2 seconds.

> It doesn't seem to be even doing that, though they're
> separate invocations of DMD.

I didn't configure the build infrastructure!

> > And all builds are release builds... what good is a debug
> > build? DMD
> > is unbelievably slow in debug. If it wasn't already slow
> > enough... if
> > I try and build with a debug build, it takes closer to 5
> > minutes.
> >
> > I suspect one part of the problem is that DMD used to be built
> > with a C compiler, and now it's built with DMD... it really
> > should be built with LDC at least?
>
> Could be part of the problem on Windows, dunno.

Well... ffs... people need to care about this! >_<