[LLVMdev] Quad-Core ARMv7 Build Slave Seeks Noble Purpose

Mikael Lyngvig
Thu, 14 Nov 2013 02:36:26 -0000

A quick question while I am adding a tiny section on ccache to the
HowToAddABuilder document: Why do you set CCACHE_CPP2 to yes?  From reading
the manual, I get the impression that this is much slower than the default
and that it should only be used with tricky compilers or when debugging.
 Is Clang such a tricky compiler?  If so, I suppose Clang should be fixed,
not the ccache configuration.

-- Mikael



2013/11/14 Dmitri Gribenko <gribozavr at gmail.com>

> On Wed, Nov 13, 2013 at 5:28 PM, Mikael Lyngvig <mikael at
lyngvig.org>
> wrote:
> > Hi Dmitri,
> >
> > I am not using any kind of cache (didn't even know of ccache).  I
have
> now
> > installed ccache.  Perhaps ccache should be mentioned in the buildbot
> > document so that every buildbot owner knows about it?
>
> Possibly.
>
> > It is currently running Arch Linux ARM.  if there are good reasons to
> switch
> > to something else, I'll be happy to do that, although I am
generally very
> > happy about Arch Linux.
> >
> > What do you want me to build?  LLVM?  Clang?  Both plus test suite?
>
> Personally, I see more value in building LLVM, Clang, possibly lld,
> without test suite.  This is the way that most build bots operate.
> Test suite takes a long time to run, and this increases the iteration
> time.
>
> As an example, you could look at the configuration in zorg repository
> that corresponds to this buildbot:
>
> http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-debian-fast
>
> It uses CMake/ninja, which will give you the best possible iteration time.
>
> In order to use ccache, you need ensure that these environment
> variables are set:
>
> CC="ccache clang"
> CXX="ccache clang++"
> CCACHE_CPP2=yes
> export CC CXX CCACHE_CPP2
>
> (Of course, you can use gcc/g++ as compilers.)
>
> Dmitri
>
> --
> main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
> (j){printf("%d\n",i);}}} /*Dmitri Gribenko <gribozavr at
gmail.com>*/
>
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