[cfe-dev] Fwd: clang++ vs g++ compilation speed for ace-tao servants

[David Blaikie]

On Wed, Oct 30, 2013 at 11:59 PM, Igor Vagulin <igor.vagulin at gmail.com>wrote:

> Hi All,
>
> We are evaluating switch to clang from gcc for our c++ application.
> Main focus is compilation speed, but we also look at address/memory
> sanitizer, c++11 support and c++ modules. I've tried to compile our
> project with clang++ but resulting compilation time is more than with
> gcc. Can someone give me a hint where might be a problem?
>
> Our project is bunch of ace-tao corba servants. Overall time with
> clang++ is about twice more than with gcc. To reproduce problem I
> preprocesssed one file and then compile it, result same - twice longer
> compilation. Don't know where to look further.
>

If you're lucky, someone might look for you if you attach (or link to, if
it's too big to attach) an example of the problem.

Otherwise, you might want to get started with a profiler and see where the
hot parts of Clang/LLVM are in your example.

(also, consider trying with Clang top of tree (straight from svn/git) - the
project moves fairly quickly)


> [root at ivagulin-pc ~]# time clang++ -c RemoveClusterObserverClang.cpp
> real    0m1.283s
> user    0m1.254s
> sys    0m0.024s
> [root at ivagulin-pc ~]# time g++ -c RemoveClusterObserverGcc.cpp
> real    0m0.576s
> user    0m0.524s
> sys    0m0.048s
>
> I use llvm-3.3 and cfe-3.3 compiled with folowing options. Sources of
> RemoveClusterObserver*cpp attached.
> + cmake -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_BUILD_TYPE=Release
> '-DCMAKE_CXX_FLAGS_RELEASE=-O3 -g -mtune=amdfam10 -march=i686'
> '-DCMAKE_C_FLAGS_RELEASE=-O3 -g -mtune=amdfam10 -march=i686'
> -DCMAKE_EXE_LINKER_FLAGS_RELEASE=-Wl,--as-needed -Wl,--strip-all'
> '-DCMAKE_MODULE_LINKER_FLAGS_RELEASE=-Wl,--as-needed -Wl,--strip-all'
> '-DCMAKE_SHARED_LINKER_FLAGS_RELEASE=-Wl,--as-needed -Wl,--strip-all
> -shared' -DCMAKE_SKIP_RPATH=YES -DBUILD_SHARED_LIBS=YES
> -DLLVM_ENABLE_TIMESTAMPS=NO ..
>
> Igor Vagulin
>
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20131031/ef3157f2/attachment.html>