I am trying to compile a multi threaded application to WebAssembly. The application uses OpenMP for multithreading.
To compile I am using the Emscripten framework.
I have already downloaded the source files for OpenMP and compiled it for my host machine using make. With the following command I can get it to link with a simple demo application on my machine:
g++ -Wall -Werror -pedantic main.o -o main.x /$PATH_TO_OPENMP/build/runtime/src/libgomp.a -pthread -lstdc++ -Wl,--no-as-needed -ldl
I then tried to compile OpenMP to the llvm bytecode format used by Emscripten. To do so I tried to run 'emmake make', so that the emscripten framework executes the OpenMP makefiles with a suitable compiler. As emscripten does not like shared object files I compiled it to static library .a files.
This works and actually gives me object files to which I can link.
I then wanted to link my demo application with the following command
em++ -Wall -Werror -pedantic main.o -o main.html /home/main/data/Programming/openMP/openmp_web/build/runtime/src/libgomp.a -pthread -lstdc++ -Wl,--no-as-needed -ldl
But I get these warnings, that it couldn't link to OpenMP files:
shared:WARNING: object /tmp/emscripten_temp_ONa0eU_archive_contents/kmp_atomic.cpp.o is not a valid object file for emscripten, cannot link
.
.
shared:WARNING: object /tmp/emscripten_temp_ONa0eU_archive_contents/kmp_str.cpp.o is not a valid object file for emscripten, cannot link
shared:WARNING: object /tmp/emscripten_temp_ONa0eU_archive_contents
So I figured I must have compiled OpenMP with the wrong compiler. I then tried to change the compiler when building the library by using the following commands:
cmake -DCMAKE_C_COMPILER=emcc -DCMAKE_CXX_COMPILER=em++ -DLIBOMP_LIB_TYPE=normal -DLIBOMP_ENABLE_SHARED=OFF -DCMAKE_BUILD_TYPE=Release -DLIBOMP_ARCH=x86_64 OPENMP_STANDALONE_BUILD=1 ..
emmake make
But this just gives strange errors on some missing system variables
/home/main/data/Programming/openMP/openmp_web/runtime/src/kmp_platform.h:82:2: error: Unknown OS
/home/main/data/Programming/openMP/openmp_web/runtime/src/kmp_platform.h:203:2: error: Unknown or unsupported architecture
In file included from /home/main/data/Programming/openMP/openmp_web/runtime/src/kmp_alloc.cpp:13:
In file included from /home/main/data/Programming/openMP/openmp_web/runtime/src/kmp.h:77:
/home/main/data/Programming/openMP/openmp_web/runtime/src/kmp_os.h:171:2: error: "Can't determine size_t printf format specifier."
Does anyone have an idea on what I could do differently?
Related
I am working on a project which eventually requires me to link my code against my customized version of libc, libstdc++ and libgcc. Now I am learning what libraries are linked by default.
I tried to compile my project code with -nolibc and manually provide the needed libraries in the argument list.
g++ -fuse-ld=gold -O2 -o main -static -nolibc main.cpp -lgcc -lm -lc
I got the following error, showing that I missed some libraries.
/usr/lib/gcc/x86_64-linux-gnu/9/libgcc_eh.a(unwind-dw2-fde-dip.o):function _Unwind_Find_FDE: error: undefined reference to 'dl_iterate_phdr'
Which library is missing here?
I am new to C++ compiling/linking.
I am trying to link all libraries statically with gcc, I tried using LDFLAGS=-static but did not work. Error message showed:
/bin/sh ./libtool --tag=CXX --mode=link /home/dizhang/lib/hdf5/bin/h5c++ -g -O2 -L/home/dizhang/lib/blitz/lib -L/home/dizhang/lib/libconfig/lib -o angora src/libangora.la -lblitz -lconfig++
libtool: link: /home/dizhang/lib/hdf5/bin/h5c++ -g -O2 -o angora -L/home/dizhang/lib/blitz/lib -L/home/dizhang/lib/libconfig/lib src/.libs/libangora.a -L/bgsys/drivers/V1R2M2/ppc64/comm/lib64 -L/bgsys/drivers/V1R2M2/ppc64/comm/lib -L/bgsys/drivers/V1R2M2/ppc64/spi/lib -lpthread -lm /home/dizhang/lib/blitz/lib/libblitz.a /bgsys/drivers/V1R2M2/ppc64/comm/lib/libmpichcxx-gcc.so /bgsys/drivers/toolchain/V1R2M2_base/gnu-linux/powerpc64-bgq-linux/lib/libstdc++.so /bgsys/drivers/V1R2M2/ppc64/comm/lib/libmpich-gcc.so /bgsys/drivers/V1R2M2/ppc64/comm/lib/libopa-gcc.so /bgsys/drivers/V1R2M2/ppc64/comm/lib/libmpl-gcc.so /home/dizhang/lib/libconfig/lib/libconfig++.a /bgsys/drivers/toolchain/V1R2M2_base-efix014/gnu-linux/powerpc64-bgq-linux/lib/libstdc++.so -Wl,-rpath -Wl,/bgsys/drivers/toolchain/V1R2M2_base-efix014/gnu-linux/powerpc64-bgq-linux/lib -Wl,-rpath -Wl,/bgsys/drivers/V1R2M2/ppc64/comm/lib -Wl,-rpath -Wl,/bgsys/drivers/toolchain/V1R2M2_base/gnu-linux/powerpc64-bgq-linux/lib -Wl,-rpath -Wl,/bgsys/drivers/toolchain/V1R2M2_base-efix014/gnu-linux/powerpc64-bgq-linux/lib -Wl,-rpath -Wl,/bgsys/drivers/V1R2M2/ppc64/comm/lib -Wl,-rpath -Wl,/bgsys/drivers/toolchain/V1R2M2_base/gnu-linux/powerpc64-bgq-linux/lib
/bgsys/drivers/toolchain/V1R2M2_base-efix014/gnu-linux/lib/gcc/powerpc64-bgq-linux/4.4.7/../../../../powerpc64-bgq-linux/bin/ld: attempted static link of dynamic object `/bgsys/drivers/V1R2M2/ppc64/comm/lib/libmpichcxx-gcc.so'
collect2: ld returned 1 exit status
I did some search and found that, telling Makefile -Wl -Bstatic may solve this problem, but how exactly I should change this in my Makefile?
I tried searching -Wl in Makefile but it was not in the text.
Thanks,
Di
Looks like you are trying to build HDF5 with MPI support on BGQ.
As long as you end up passing a ".so" version of a lib to gcc on BGQ -- you will see this error. You may need to check how you are passing MPI info to HDF5's configure script.
In my case (building another project that uses CMake) passing BGQ's MPI compiler wrappers to CMake always created a problem where it would try to link MPI using the shared libs instead of the static ones. To resolve this, I had to make sure to explicitly specify the ".a" variants of the MPI libs.
I've downloaded from github and built gcc. After that I've tried to compile a code with OpenMP:
../GCC/build/gcc/xgcc -B./../GCC/build/gcc/ -I./../GCC/build/x86_64-unknown-linux-gnu/libgomp -Wno-write-strings -O3 -Wall -fopenmp -lpng -o mandelbrot-omp mandelbrot-omp.cpp
Then I got the following error message:
xgcc: error: libgomp.spec: No such file or directory
I've checked and found out that libgomp directory contains the libgomp.spec file. The directory is included with -I option. What's wrong?
Im developing an android app thats loading two shared libraries. One is external, its called libpcan.so . Usually its build to libpcan.so.0.6, this somehow cant be used by my android, i so changed the gcc flags compiling it from:
arm-linux-androideabi-gcc src/libpcan.c -fPIC -shared -O2 -Wall -Wl,-soname,-libpcan.so.0 -lc -I. -I../driver -DNO_RT -o -libpcan.so.0.6
ln -sf libpcan.so.0.6 libpcan.so
to
arm-linux-androideabi-gcc src/libpcan.c -fPIC -shared -O2 -Wall -lc -I. -I../driver -DNO_RT -o -libpcan.so
This .so has the same size as the so.0.6 so i assume it worked fine.
My own c-code is getting compiled with
arm-linux-androideabi -shared src/receivetest.c src/common.c -I. -I../lib -I../driver -L../lib -L/lib -L/usr/lib -L/usr/local/lib -o libreceivetest.so
I load both of these files, so the libpcan.so and the libreceivetest.so to my app
static {
System.loadLibrary("pcan");
System.loadLibrary("receivetest");
}
When I'm trying to launch that app i get the error message:
07-14 11:12:43.812: E/AndroidRuntime(753): java.lang.ExceptionInInitializerError
07-14 11:12:43.812: E/AndroidRuntime(753): Caused by: java.lang.UnsatisfiedLinkError: Cannot load library: reloc_library[1306]: 36 cannot locate 'CAN_Open'...
My receivetest is using that function, but since it declared in the libpcan.so and im also loading that library, i don't know where that error could come from.
I'd just guess its an error in my clags, since I'm new to building .so files via using gcc in the shell i don't really understand all the flags im using.
It's quite long since i solved this. But I haven't ever marked this question as solved.
Thanks to jww for reminding me.
As I've said in the comment to my question, the link to the function CAN_Open was missing due to a missing parameter at compiling the .so-file. The function CAN_Open is a part of the libpcan.so and by skipping the link to that file the CAN_Open function just never made it into the receivetest.so .
I'm currently trying to compile a dynamically linked library (for a plugin system) using Windows and MinGW.
I compile each objects using this command line :
mingw-g++ -fPIC test.cpp
And the library using this line:
mingw-g++ -rdynamic -shared -Wl,-soname,test.so.1 -o test.so test.o
It doesn't work at all (using GCC with Linux, a similar line works though) : fPIC and rdynamic are ignored for some reason.
And while trying to make the library, it fails because the compiler try to link it with objects that are supposed to be resolved as I dynamically link it with the main binary.
So how do you compile this using MinGW?
Thanks :) !
-fPIC and -rdynamic are ignored because they are unused for Windows.
Also, .so is not the correct output extension for libraries on Windows.
To make a shared library for/on windows with GCC:
mingw-g++ -c file.cpp -o file.o
mingw-g++ -shared -Wl,--out-implib,libfile.a -o file.dll file.o
No more, no less.
And, documentation is always lovely to have: http://www.mingw.org/wiki/sampleDLL