[Openmp-dev] _OPENMP undefined unless compiling with -fopenmp=libiomp5

[Hahnfeld, Jonas]

Hi Michael,

correct, it must be passed to LLVM/clang!

Jonas

From: Schlottke-Lakemper, Michael 
Sent: Monday, July 20, 2015 11:09 AM
To: Hahnfeld, Jonas; openmp-dev at dcs-maillist2.engr.illinois.edu
Subject: RE: [Openmp-dev] _OPENMP undefined unless compiling with
-fopenmp=libiomp5

Hi Jonas, 

Thank you for the fast answer. Just to be clear: the
-DCLANG_DEFAULT_OPENMP_RUNTIME=libomp flag is specified at configuration
time to LLVM, not to the libomp runtime, am I correct? 

Yours 

Michael 


-------- Original message --------
From: "Hahnfeld, Jonas" <Hahnfeld at itc.rwth-aachen.de> 
Date: 20/07/2015 09:50 (GMT+01:00) 
To: "Schlottke-Lakemper, Michael" <m.schlottke-lakemper at aia.rwth-aachen.de>,
openmp-dev at dcs-maillist2.engr.illinois.edu 
Subject: RE: [Openmp-dev] _OPENMP undefined unless compiling with
-fopenmp=libiomp5 
Hi Michael,

there is a CMake configuration "-DCLANG_DEFAULT_OPENMP_RUNTIME=libomp" which
one can use to make "-fopenmp" work by default.
And from my information there are plans to make it the default when this
library is fully integrated into the LLVM build system. This is currently
work in progress...

Greetings,
Jonas

From: openmp-dev-bounces at cs.uiuc.edu [mailto:openmp-dev-bounces at cs.uiuc.edu]
On Behalf Of Schlottke-Lakemper, Michael
Sent: Sunday, July 19, 2015 7:58 AM
To: openmp-dev at dcs-maillist2.engr.illinois.edu
Subject: [Openmp-dev] _OPENMP undefined unless compiling with
-fopenmp=libiomp5

Hi everyone, 

Right now we have to provide not just “-fopenmp” but “-fopenmp=libiomp5” if
we want full support for OpenMP when compiling on Linux (without the
explicit library, _OPENMP is undefined and there is only a single thread).
Are there plans to drop this requirement and support plain “-fopenmp”? I’m
asking since it would make things much easier for our users when
transitioning from gcc to clang.

Thanks a lot!

Michael

--
Michael Schlottke-Lakemper

SimLab Highly Scalable Fluids & Solids Engineering
Jülich Aachen Research Alliance (JARA-HPC)
RWTH Aachen University
Wüllnerstraße 5a
52062 Aachen
Germany

Phone: +49 (241) 80 95188
Fax: +49 (241) 80 92257
Mail: m.schlottke-lakemper at aia.rwth-aachen.de
Web: http://www.jara.org/jara-hpc
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