Profiling DMD's Compilation Time with dmdprof

[Manu]

Wed, Nov 14, 2018 at 12:25 AM Vladimir Panteleev via
Digitalmars-d-announce <digitalmars-d-announce at puremagic.com> wrote:
>
> On Thursday, 8 November 2018 at 07:54:56 UTC, Manu wrote:
> > 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 just got to try a side-by-side comparison of a release and
> debug (as in `make -f posix.mak BUILD=debug`) build of DMD.
>
> With a 25KLOC project, the debug build is only 36% slower.
>
> Maybe the experience on Windows / Visual Studio is very different.

I'm not sure how VisualStudio (read: MSBuild) should behave
differently than make?
It's not like the build script is taking a long time, it's the
invocation of DMD that takes 100% of that time.

36% slower seems highly optimistic? Perhaps you're building a debug
build of DMD with a debug build of DMD? I guess that wouldn't be so
slow... I suspect it's the optimiser that's very slow?