I have a problem with compiling a fortran program with the gfortan complier.
The main program is located in main.f. So, I write in console:
gfortran D:\test\test.f
But it displays me a lot of errors such as:
C:\Users\Efds~1\AppData\Local\Temp\cchFNGgc.o:test.f:<.test+0x3a>: undefined reference to '_gridw_'
C:\Users\Efds~1\AppData\Local\Temp\cchFNGgc.o:test.f:<.test+0x3a>: undefined reference to '_gridz_'
etc.
I think it's because of functions gridw, gridz etc. are located in other *.f files. But I don't know how to link these all together.
Also, I tried to use Compaq Visual Fortran Complier, but it didn't help me.
A basic command for compiling and linking multiple source files into one executable would be
gfortran -o executable source1.f source2.f source3.f
taking care that any .f file you specify is named to the right of any other source files on which it depends. All of this, and much more besides, is well covered in the compiler's documentation.
As noted above, you can compile several files with the same command, but it's quite unusual.
You may prefer first compile to object files (".o") :
gfortran -c gridw.f
gfortran -c gridz.f
And then compile the program
gfortran test.f grodw.o gridz.o
If you have many files to link, it may be interesting to build a library:
ar cru mylib.a gridw.o gridz.o
gfortran test.f mylib.a
If you name your library libSOMETHING.a, you can simply write
gfortran test.f -lSOMETHING
Related
I have been trying to compile a large Fortran code with many files in it on a HPC with the use of CMake. CMake properly configures and generates a Makefile. While Making, I get an error saying '/bin/sh: ftn: command not found'. The Makefile tries to compile the code like this->
ftn -o CMakeFiles/s3d.x.dir/modules/param_m.f90.o
When I compile it on my personal system or another HPC, it goes like->
mpif90 -o CMakeFiles/s3d.x.dir/modules/param_m.f90.o
I don't know why CMake is not able to put actual compilers in place of 'ftn'.
I would really appreciate if any suggestions come up.
I want to create a static library libmylib.a from mylib.c/.h and link it to a project to use this library in bootloader code using the arm-none-eabi-gcc cross compiler in ubuntu 20.04 LTS.
I have an electronic engineering background, so I'm kind of new in this compiler and linker stuff.
What I know:
I've been searching about this, and found out that '.a' are just packed '.o' files, and that's it. You can do it using ar in linux. I don't know how to manage the dependencies for this '.a' file, for example, or how to link it to the project.
What I want to know:
I really want to understand how it works, to compile and generate the bin, elf or hex files using these static libraries for arm using the arm-none-eabi-gcc cross compiler (found some for linux), but I don't know how to search for this properly, how to learn it in a linear way. If you guys could help me on this I would be really grateful.
First you create your library objects. Let us say that you have a foo function written in foo.c, then you do:
arm-none-eabi-gcc -c foo.c
The -c options tells the compiler to stop after assembling and no go further.
Then you need to create the .a file
arm-none-eabi-ar -rc libfoo.a foo.o
this command creates a static library called libfoo.a
At the end you compile your main with:
arm-none-eabi-gcc -L. -lfoo main.c -o main
Note that in -l flag we don put "lib" and ".a", those are automagically added. The -L. flag tells gcc to look into the current folder for library files.
I'm attempting to do a release of some software and am currently working through a script for the build process. I'm stuck on something I never thought I would be, statically linking LAPACK on x86_64 linux. During configuration AC_SEARCH_LIB([main],[lapack]) works, but compilation of the lapack units do not work, for example undefiend reference to 'dsyev_' --no lapack/blas routine goes unnoticed.
I've confirmed I have the libraries installed and even compiled them myself with the appropriate options to make them static with the same results.
Here is an example I had used in my first experience with LAPACK a few years ago that works dynamically, but not statically: http://pastebin.com/cMm3wcwF
The two methods I'm using to compile are the following,
gcc -llapack -o eigen eigen.c
gcc -static -llapack -o eigen eigen.c
Your linking order is wrong. Link libraries after the code that requires them, not before. Like this:
gcc -o eigen eigen.c -llapack
gcc -static -o eigen eigen.c -llapack
That should resolve the linkage problems.
To answer the subsequent question why this works, the GNU ld documentation say this:
It makes a difference where in the command you write this option; the
linker searches and processes libraries and object files in the order
they are specified. Thus, foo.o -lz bar.o' searches libraryz' after
file foo.o but before bar.o. If bar.o refers to functions in `z',
those functions may not be loaded.
........
Normally the files found this way are library files—archive files
whose members are object files. The linker handles an archive file by
scanning through it for members which define symbols that have so far
been referenced but not defined. But if the file that is found is an
ordinary object file, it is linked in the usual fashion.
ie. the linker is going to make one pass through a file looking for unresolved symbols, and it follows files in the order you provide them (ie. "left to right"). If you have not yet specified a dependency when a file is read, the linker will not be able to satisfy the dependency. Every object in the link list is parsed only once.
Note also that GNU ld can do reordering in cases where circular dependencies are detected when linking shared libraries or object files. But static libraries are only parsed for unknown symbols once.
I am trying to link a C++ module using GCC, essentially like this:
gcc -c hello.c
g++ -c world.cpp
gcc -ohello -lstdc++ hello.o world.o
Note that I use -lstdc++ to link the C++ module in, so that I can use gcc instead of g++. The problem is that I'm getting the error:
undefined reference to `operator new(unsigned long)'
(Assuming that world.cpp contains at least one call to new.)
This error is fixed if I put -lstdc++ at the end of the linker line, like this:
gcc -ohello hello.o world.o -lstdc++
I am aware that this question has been asked many times here, but I have a special requirement. I am not directly calling GCC. I am using a build system for a different programming language (Mercury) which is calling GCC on my behalf, and I can't easily modify the way it calls GCC (though I can specify additional libraries using the LDFLAGS environment variable). So I have two additional requirements:
I cannot use g++ to link (only gcc) -- that is why I am doing the -lstdc++ trick above rather than simply linking with g++).
I don't think that I can control the order of the linker commands -- Mercury will put the .o files on the command-line after any libraries.
I understand the basic reason why the order is important, but what is baffling me is why did this break now? I just updated to Ubuntu 11.10 / GCC 4.6.1. I have been successfully compiling this program for years using precisely the above technique (putting -lstdc++ first). Only now has this error come up. An unrelated program of mine links against OpenGL using -lgl and that too broke when I upgraded and I had to move -lgl to the end of the command-line. I'm probably going to discover that dozens of my programs no longer compile. Why did this change? Is there something wrong with my new system or is that the way it is now? Note that these are ordinary shared libraries, not statically linked.
Is there anything I can do to make GCC go back to the old way, where the order of libraries doesn't matter? Is there any other way I can convince GCC to link libstdc++ properly without moving it after the .o files on the command-line?
If Mercury puts object files after libraries, Mercury is broken. Libraries belong after object files - always. You may sometimes get away with the reverse order, but not reliably. (Static libraries must go after the object files that reference symbols in the static library. Sometimes, a linker will note the symbols defined by a shared library even when none of the symbols are used; sometimes, the linker will only note the shared library symbols if the shared library provides at least one symbol.)
I downloaded lapack 3.3.0 version and mingw (with all libraries) after that I succeded to make blas.dll by gfortran --shared -o blas.dll blas\src\*.f -O
I could not succeeded to make lapack.dll by gfortran --shared -o lapack.dll src\*.f blas.dll -O
I got the following error
gfortran: error: CreateProccess: No such file or directory
Note: I set path to mingw/bin and also copied dlamch.f and slamch.f from install directory to src directory.
:: instructions got from this site
http://www.codingday.com/compile-lapack-and-blas-as-dll-on-windows/
What should I do
I donwloaded lapack and can reproduce the error.
As is indicated in the comments on the page you referred to, you might be running into a problem with the command line being too long for the shell to handle. Try first compiling all source files, and then linking them, in two separate steps.
gfortran -c src/*.f -O
gfortran -shared -o lapack.dll *.o blas.dll
When I did this the CreateProcess error went away, but unfortunately some undefined reference errors popped up next. It appears there are references to a couple of blas functions which aren't included in the blas sources accompanying lapack (I think they might be C functions).