[cfe-dev] Clang on Windows targteing gcc compiles very slowly

[Edward Diener]

On 5/30/2015 1:35 AM, Yaron Keren wrote:
> Try to  -DLLVM_ENABLE_THREADS:BOOL=OFF. Might not make a big difference.

Does this mean thread support in clang itself ? I need thread support in 
clang as I compile multi-threaded source.

>
>
> 2015-05-30 5:08 GMT+03:00 Edward Diener
> <eldlistmailingz at tropicsoft.com
> <mailto:eldlistmailingz at tropicsoft.com>>:
>
>     On 5/29/2015 9:35 PM, Justin Bogner wrote:
>
>         On Friday, May 29, 2015, Edward Diener
>         <eldlistmailingz at tropicsoft.com
>         <mailto:eldlistmailingz at tropicsoft.com>
>         <mailto:eldlistmailingz at tropicsoft.com
>         <mailto:eldlistmailingz at tropicsoft.com>>>
>         wrote:
>
>              I test Boost libraries mostly on Windows using various
>         version of
>              gcc 4.3 and up, VC++ 8.0 and up, and the latest version of
>         clang
>              which I build from source using mingw/gcc-4.8.1 in release
>         mode.
>
>              While clang is a great compiler when it comes to testing code,
>              getting intelligent error message, and implementing the
>         latest C++
>              standard, it is noticably slower ( 2x or 3x at minimum )
>         than the
>              other compilers I use.
>
>              The clang command line parameters usually being used are
>         usually
>              along the lines of:
>
>              -c -x c++ -O0 -g -fno-inline -Wall -g -march=i686 -m32
>
>              with the addition of 'std=c++11' occasionally depending on
>         the test.
>
>              Does anybody have any idea why clang is so much slower than
>         any of
>              the other compilers I use ? It does not seem to matter
>         whether it is
>              in C++03 mode or C++11 mode, it is noticeably slower than
>         the other
>              compilers.
>
>
>         How are you building clang? I suspect that you're using a debug
>         build of
>         clang, which is quite slow.
>
>
>     "which I build from source using mingw/gcc-4.8.1 in release mode."