llvm dev - Jun 2012 - [LLVMdev] Ninja (make replacement)

Christoph Erhardt <christoph at sicherha.de> writes:
> Hi Mikael,
>
>> My Clang build used to take 59:29 minutes using MinGW Makefiles.  With
>> Ninja, it takes 18:43 minutes!  That's a speed up of factor three.
> sorry for asking the obvious question: Are you comparing against a
> parallel "make -j<n>"? :-)
I'm pretty sure he isn't. Building Clang+LLVM with MinGW, maybe ninja is
faster than gmake by a few dozen seconds on Windows. The real advantage
is over the build tools traditionally used with the Visual Studio
toolchain, because all of have limited support for parallelization.

The other aspect where ninja shines over all other build tools is at
being fast parsing the makefiles and determining what needs to be
rebuilt. This is something people appreciate while rebuilding big
projects after small changes.

BTW Mikael, have you checked http://llvm.org/docs/CMake.html ?

I am building with MinGW and my experience is that "make -jN" either
doesn't work (because of problems with different processes updating the
same library using ranlib or something like that).  And then there's the
issue I mentioned in the previous doc.

I think Ninja is a gift from some heavenly dimension.  Others may disagree.
 But I think any Windows developer should take a look at it, no matter if
they are using GNU Make or Visual Studio.

By the way, I forgot to use my brain when I sent the first link: It is a
Windows-only link.  For non-Windows users and people who want to see the
source before they use it, use this link: http://martine.github.com/ninja/

Yes, I am quite familiar with the CMake documentation, but why are you
asking?  I use CMake all the time for my MinGW32 and MinGW64 builds.  Now I
use "CMake -G Ninja" :-)

2012/6/18 Óscar Fuentes <ofv at wanadoo.es>
> Christoph Erhardt <christoph at sicherha.de> writes:
>
> > Hi Mikael,
> >
> >> My Clang build used to take 59:29 minutes using MinGW Makefiles. 
With
> >> Ninja, it takes 18:43 minutes!  That's a speed up of factor
three.
> > sorry for asking the obvious question: Are you comparing against a
> > parallel "make -j<n>"? :-)
>
> I'm pretty sure he isn't. Building Clang+LLVM with MinGW, maybe
ninja is
> faster than gmake by a few dozen seconds on Windows. The real advantage
> is over the build tools traditionally used with the Visual Studio
> toolchain, because all of have limited support for parallelization.
>
> The other aspect where ninja shines over all other build tools is at
> being fast parsing the makefiles and determining what needs to be
> rebuilt. This is something people appreciate while rebuilding big
> projects after small changes.
>
> BTW Mikael, have you checked http://llvm.org/docs/CMake.html ?
>
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Mikael Lyngvig <mikael at lyngvig.org> writes:

[snip]
> Yes, I am quite familiar with the CMake documentation, but why are you
> asking?
That's not the cmake documentation, that's the LLVM cmake documentation:
a short document that tries to explain everything you need to know about
cmake to build LLVM. I had the impression that you were duplicating a
large chunk of the info contained on that page. OTOH it's my personal
opinion that you may be explaining too much: it is not necessary to
explain, nor even mention, the different available build tools on
Windows. As LLVM and Clang are developer tools, one can suppose that the
user knows how to run a build. IMHO you only need to explain the bits
that are specific to LLVM. As cmake might not be popular enough yet, a
bit of an introduction is needed, but no more.

I haven't thoroughly read your proposed documentation, sorry if my
opinions are off-base.

[snip]