[Openmp-dev] issue with opennp and clang

Tue Nov 25 14:54:23 PST 2014

I'm not super familiar with all the parts of clang, and I don't think
I've used opt directly before. I either don't call --emit-llvm to make
the binaries, or I call it just to generate the IR. I don't know how
to compile/run the human readable LLVMIR with omp runtime calls.

On Tue, Nov 25, 2014 at 4:27 PM, Amir H. Ashouri
<amirhossein.ashouri at gmail.com> wrote:
> Jeremey,
>
> Could you let me know if in the LLVM-openMP project we have the same opt
> <flags> as the default llvm-opt <flags> ?
>
> as I am running these procedures:
>
> 1- clang(Openmp) -S -emit-llvm -fopenmp llvm_openmp.c
>
> 2- opt(Openmp) <some flags> -S -o hello_opt.ll hello.ll
>
> 3- clang(Openmp) hello_opt.ll -lm
>
>  I am getting :
>
> [ashouri at savina openmp_power]$ clang -v llvm_openmp.ll -lm
>
> clang version 3.5.0 (https://github.com/clang-omp/clang
> 05ab95f7cb2779bbf20341ae6ed293106de5afda) (https://github.com/clang-omp/llvm
> e45b045553e027cbe400cbb8ac8c264abbbfaf83)
>
> Target: x86_64-unknown-linux-gnu
>
> Thread model: posix
>
> Found candidate GCC installation: /usr/lib/gcc/i686-redhat-linux/4.4.4
>
> Found candidate GCC installation: /usr/lib/gcc/i686-redhat-linux/4.4.7
>
> Found candidate GCC installation: /usr/lib/gcc/x86_64-redhat-linux/4.4.4
>
> Found candidate GCC installation: /usr/lib/gcc/x86_64-redhat-linux/4.4.7
>
> Selected GCC installation: /usr/lib/gcc/x86_64-redhat-linux/4.4.7
>
> Candidate multilib: .;@m64
>
> Candidate multilib: 32;@m32
>
> Selected multilib: .;@m64
>
>  "~/llvm/build/Debug+Asserts/bin/clang" -cc1 -triple
> x86_64-unknown-linux-gnu -emit-obj -mrelax-all -disable-free -main-file-name
> llvm_openmp.ll -mrelocation-model static -mdisable-fp-elim -fmath-errno
> -masm-verbose -mconstructor-aliases -munwind-tables -target-cpu x86-64
> -target-linker-version 2.20.51.0.2 -v -dwarf-column-info -resource-dir
> ~llvm/build/Debug+Asserts/bin/../lib/clang/3.5.0 -fdebug-compilation-dir
> /usa/ashouri/phase_ordering/openmp_power -ferror-limit 19 -fmessage-length
> 204 -mstackrealign -fobjc-runtime=gcc -fdiagnostics-show-option
> -fcolor-diagnostics -o /tmp/llvm_openmp-3af5c7.o -x ir llvm_openmp.ll
>
> clang -cc1 version 3.5.0 based upon LLVM 3.5.0 default target
> x86_64-unknown-linux-gnu
>
>  "/usr/bin/ld" --eh-frame-hdr -m elf_x86_64 -dynamic-linker
> /lib64/ld-linux-x86-64.so.2 -o a.out
> /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crt1.o
> /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crti.o
> /usr/lib/gcc/x86_64-redhat-linux/4.4.7/crtbegin.o
> -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7
> -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64 -L/lib/../lib64
> -L/usr/lib/../lib64 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../..
> -L/~/llvm/build/Debug+Asserts/bin/../lib -L/lib -L/usr/lib
> /tmp/llvm_openmp-3af5c7.o -lm -L. -L/~/openmp/runtime/exports/lin_32e/lib
> -L~/openmp/runtime/exports/lin_32e/lib -lgcc --as-needed -lgcc_s
> --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed
> /usr/lib/gcc/x86_64-redhat-linux/4.4.7/crtend.o
> /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crtn.o
>
> /tmp/llvm_openmp-3af5c7.o: In function `main':
>
> llvm_openmp.ll:(.text+0x75): undefined reference to `__kmpc_fork_call'
>
> /tmp/llvm_openmp-3af5c7.o: In function `.omp_microtask.':
>
> llvm_openmp.ll:(.text+0xf1): undefined reference to `omp_get_thread_num'
>
> llvm_openmp.ll:(.text+0xf9): undefined reference to `omp_get_num_threads'
>
> llvm_openmp.ll:(.text+0x101): undefined reference to `omp_get_max_threads'
>
> llvm_openmp.ll:(.text+0x12d): undefined reference to `__kmpc_cancel_barrier'
>
>
> its strange cuz when I dont invoke -emit-llvm and just compiler and link at
> once with clang(openmp) -fopenmp foo.c the executable can be run with max
> threads.
>
>
> Appreciate any helps,
>
>
> -Amir
>
>
> On Wed, Nov 12, 2014 at 11:19 AM, Amir H. Ashouri
> <amirhossein.ashouri at gmail.com> wrote:
>>
>> Thanks all for their responses. I re-compile the clang with OpenMP support
>> and the library files and set the library paths and it worked finally. I
>> might think as Alexey mentioned, that the CentOS was using the default clang
>> to that matter before head.
>>
>> Regards,
>>
>> -Amir
>>
>> On Wed, Nov 12, 2014 at 11:55 AM, Jack Howarth
>> <howarth.mailing.lists at gmail.com> wrote:
>>>
>>> Amir,
>>>     You didn't say what platform you are trying to use clang-omp on. If
>>> it is OS X, the llvm34-3.4.2-2 fink package (http://finkproject.org) has a
>>> port of the clang-omp changes at commit
>>> 13e28835a005b44481387a32666ed39a7db58eb6 over the llvm 3.4.2 release. While
>>> the fink llvm35 packaging isn't released yet, you can obtain the necessary
>>> llvm35* packaging files to build it from
>>> http://fink.cvs.sourceforge.net/viewvc/fink/experimental/fangism/finkinfo/.
>>> This has a port of the clang-omp changes at commit
>>> 3f687cbc520a8b8f506d7941f0cebd6c5af1cef6 over llvm 3.5.0 with the openmp
>>> trunk changes at r219214.
>>>              Jack
>>>
>>> On Fri, Nov 7, 2014 at 3:22 PM, Amir H. Ashouri
>>> <amirhossein.ashouri at gmail.com> wrote:
>>>>
>>>> I did that.
>>>>
>>>> Downloaded and compiled with gcc, then export all the PATHs. Otherwise,
>>>> It would have given me compile error because the "omp.h" is different here.
>>>>
>>>> -Amir
>>>>
>>>> On Fri, Nov 7, 2014 at 3:13 PM, Millad Ghane <millad.mg at gmail.com>
>>>> wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>> You haven't imported the openmp library to Clang yet. It simply ignores
>>>>> the pragmas.
>>>>>
>>>>> Go to this link and follow the instructions.
>>>>> clang-omp.github.io
>>>>>
>>>>>
>>>>> Best Regards,
>>>>> Millad
>>>>>
>>>>>
>>>>> On Friday, November 7, 2014, Amir H. Ashouri
>>>>> <amirhossein.ashouri at gmail.com> wrote:
>>>>>>
>>>>>> Greetings,
>>>>>>
>>>>>> so I tried to use opennp with one of the latest version of clang,
>>>>>> clang version 3.4.2 (tags/RELEASE_34/dot2-final). Followed the procedure to
>>>>>> compilre and export the library PATHs, Compiling my hello.c using :
>>>>>>
>>>>>> clang -fopenmp hello.c
>>>>>>
>>>>>> and then running it, still it can't use more than 1 thread:
>>>>>>
>>>>>> Bash-4.1$ ./a.out
>>>>>> Hello from thread 0, nthreads 1
>>>>>>
>>>>>> I tried to manually export export OMP_NUM_THREADS=8 but that didn't
>>>>>> solve anything as well, As a workaround I define  #pragma omp parallel
>>>>>> num_threads(#noofthreads) inside the source code but still the issue is
>>>>>> there.
>>>>>>
>>>>>> Any suggestions would be appreciated.
>>>>>>
>>>>>>
>>>>>> -Amir
>>>>>>
>>>>>>
>>>>>> p.sl: This is the hello.c:
>>>>>>
>>>>>> #include <omp.h>
>>>>>> #include <stdio.h>
>>>>>> int main() {
>>>>>> #pragma omp parallel
>>>>>> printf("Hello from thread %d, nthreads %d\n", omp_get_thread_num(),
>>>>>> omp_get_num_threads
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Sent from my iPhone
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Openmp-dev mailing list
>>>> Openmp-dev at dcs-maillist2.engr.illinois.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/openmp-dev
>>>>
>>>
>>
>