[Openmp-dev] OMPT on Windows

[Cramer, Tim]

Hi Olga,
 
To be honest: I am not really aware of Windows. As far as I know weak symbols are not supported on Windows, so that we need a
different strategy. The OMPT specification [1] says
 
"Compiler and linker don't support weak symbols. On systems that don't support weak symbols, different implementation strategies are
needed for static and dynamic linking. For a static library implementation of an OpenMP runtime library, the library can provide a
stub version of ompt_initialize in a separate object file. In this case, the linker will include the OpenMP library's stub
implementation of ompt_initialize only if no tool supplied version is already present when the OpenMP runtime library is used to
resolve undefined symbols. An OpenMP implementation used as a dynamic library can define ompt_initialize as a global symbol. The
version in the OpenMP library would be invoked only if no tool-supplied implementation of ompt_initialize is statically linked in
the executable or a tool library that appears before the OpenMP runtime library in the dynamic library search path during
execution."
 
I will discuss with Jonas how / if we can fix this. At least we should ensure that compiling is possible on Windows, at least with
deactivating OMPT.
 
Regards,
 
Tim
 
[1] http://openmp.org/mp-documents/ompt-tr2.pdf
 
 
From: Malysheva, Olga [mailto:Olga.Malysheva at intel.com] 
Sent: Thursday, June 04, 2015 2:42 PM
To: Hahnfeld, Jonas
Cc: John Mellor-Crummey (johnmc at rice.edu); Cramer, Tim; 'openmp-dev at dcs-maillist2.engr.illinois.edu'
Subject: OMPT on Windows 
 
Hi Jonas, 
 
How do you intend to support OMPT on Windows? 
The code currently committed to the project can be compiled only on unix-like systems due to the attribute 'weak' specified for the
initialization function (in ompt-general.c):
 
_OMP_EXTERN __attribute__ (( weak ))
int ompt_initialize(ompt_function_lookup_t ompt_fn_lookup, const char *version,
                    unsigned int ompt_version)
{
    return no_tool_present;
}
 
Thank you.
 
Regards,
Olga
 
-----Original Message-----
From: openmp-dev-bounces at cs.uiuc.edu [mailto:openmp-dev-bounces at cs.uiuc.edu] On Behalf Of Hahnfeld, Jonas
Sent: Thursday, April 9, 2015 4:25 PM
To: 'openmp-dev at dcs-maillist2.engr.illinois.edu'
Cc: John Mellor-Crummey (johnmc at rice.edu); Cramer, Tim
Subject: [Openmp-dev] Patches to support OMPT
 
Hi all!
 
After some months of work, we would like to share our patches to add support for OMPT[1] to this version of the Intel runtime.
Implementation was mainly done by John Mellor-Crummey from Rice University in a repository at Google Code[2].
 
Support for OMPT is disabled by default and therefore has to be enabled
explicitly:
With CMake, define "ompt-support": $ cmake -Dompt-support=true ..
build.pl works nearly the same: $ make build_args="--ompt-support=on"
With this switch, ompt-blame and ompt-trace will be enabled as well which can be disabled separately.
 
We've uploaded the patches to LLVM's Phabricator. Some short explanation:
0001-kmp_lock-Change-return-type-of-release-functions-fro.patch[3]
This is a preparation patch to get information about the actual release status from nested locks.
 
0002-Add-new-files-for-OMPT.patch[4]
This patch contains the new files for OMPT and the needed changes to the build infrastructure.
 
0003-Modify-runtime-to-call-correct-functions-for-OMPT.patch[5]
These are the actual changes in the runtime to issue OMPT-related functions.
All of them are surrounded by #if OMPT_SUPPORT and can be disabled (which is the default).
 
The implementation is tested with the OMPT-TestSuite[6] and conforms with the OpenMP's 2nd Technical Report[1].
Additionally we ran the OpenMP Validation Suite contained in this repository to make sure that nothing broke.
 
Please review and commit if found suitable.
We know that these are rather big patches (for a big feature), but we couldn't come up with a better splitting.
 
>From Aachen,
Tim Cramer and Jonas Hahnfeld
 
[1]: http://openmp.org/mp-documents/ompt-tr2.pdf
[2]: https://code.google.com/p/ompt-intel-openmp/
[3]: http://reviews.llvm.org/D8916
[4]: http://reviews.llvm.org/D8917
[5]: http://reviews.llvm.org/D8918
[6]: https://code.google.com/p/ompt-test-suite/
 
 
--
Jonas Hahnfeld, MATSE-Auszubildender
 
IT Center
Group: High Performance Computing
Division: Computational Science and Engineering RWTH Aachen University Seffenter Weg 23 D 52074  Aachen (Germany)
Hahnfeld at itc.rwth-aachen.de www.itc.rwth-aachen.de
 
 
 

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