[LLVMdev] llvm and openmp

[Karthik Vadambacheri Manian]

Hi Duncan,

Thanks for your prompt reply. Good to know that GCC ADA front end supports
this. Since I need to compile a huge c++ project, I am in need of a c++
compiler supporting thread local storage for non POD types. Intel's c++
compiler does but its non commercial license does not suit my research work.
If you know any other c++ compiler kindly let me know.

Note: apologies as I replied to your personal id instead of group

Thanks for your time,
karthik

On Wed, May 4, 2011 at 2:54 PM, Duncan Sands <baldrick at free.fr> wrote:

> Hi Karthik,
>
> > I am new to llvm. Does llvm has support for openmp directives like
> #pragma
> > openmp threadprivate(var)?
>
> LLVM has no special support for openmp.  The LLVM front-ends that support
> openmp, namely llvm-gcc and dragonegg, lower openmp constructs down to
> library calls the same way GCC does.  This is no coincidence: both of those
> front-ends are based on GCC and just let the GCC machinery take care of
> openmp.
> The clang front-end does not support openmp.
>
>  If so does the variable 'var' can be class objects
> > instead of Plain Old Datatypes (POD) like int, float etc. g++ allows the
> #pragma
> > openmp threadprivate(var) primitive only for the POD type. Please check
> the bug
> > link at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27557 . Please let
> me know.
>
> You are out of luck: if GCC rejects this then so will llvm-gcc and
> dragonegg.
> That said, the GCC Ada front-end does support thread-local storage non-POD
> types, so it can be done - but it jumps through a lot of hoops and the
> result
> is not very efficient.  There's a big comment in gcc/ada/a-tasatt.adb
> explaining
> how it is done and why that scheme was chosen.  You may enjoy these lines
> from
> the start of the comment:
>
>   The following notes are provided in case someone decides the
> implementation
>   of this package is too complicated, or too slow. Please read this before
>   making any "simplifications".
>
> Ciao, Duncan.
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