gfortran-5.2.0 -m32 -dynamiclib -o -shared produces bizarre files

Question

I have a small fortran code in tmp0.f

      subroutine POWERTWO (n, nsquared)
            integer, intent(in) :: n
        integer, intent(out) :: nsquared
            nsquared = n*n
            return
      end subroutine POWERTWO

that I compile into a dynamic library with :

gfortran-5.2.0 -m32 -dynamiclib ./tmp0.f -o ./tmp0.so -shared

where my gfortran was build with gcc 5.2.0 and configured as follows :

Using built-in specs.
COLLECT_GCC=gfortran-5.2.0
COLLECT_LTO_WRAPPER=/usr/local/lvm/gcc-5.2.0/libexec/gcc/x86_64-unknown-linux-gnu/5.2.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../configure --prefix=/usr/local/lvm/gcc-5.2.0 --enable-checking=release --with-gmp=/usr/local/lvm/gmp-6.0.0 --with-mpfr=/usr/local/lvm/mpfr-3.1.2 --with-mpc=/usr/local/lvm/mpc-1.0.3 --enable-languages=c,c++,fortran,objc,obj-c++ --with-isl=/usr/local/lvm/isl-0.14 --with-cloog=/usr/local/lvm/cloog-0.18.4 --program-suffix=-5.2.0
Thread model: posix
gcc version 5.2.0 (GCC)

Under OS X 10.10.5 the compilation produced (with no warning) the wanted dynamic library tmp0.dylib, but under ubuntu (15-05) I got the following warnings :

f951: Warning: unrecognized gcc debugging option: y
f951: Warning: unrecognized gcc debugging option: n
f951: Warning: unrecognized gcc debugging option: m
f951: Warning: unrecognized gcc debugging option: i
f951: Warning: unrecognized gcc debugging option: c
f951: Warning: unrecognized gcc debugging option: l
f951: Warning: unrecognized gcc debugging option: i
f951: Warning: unrecognized gcc debugging option: b

and the compilation produced, in addition to the dynamic library tmp0.so, a bunch of files :

-rw-rw-r-- 1 XXX XXX  4679 août  25 19:12 tmp0.f.192r.expand
-rw-rw-r-- 1 XXX XXX  1601 août  25 19:12 tmp0.f.193r.vregs
-rw-rw-r-- 1 XXX XXX  1602 août  25 19:12 tmp0.f.194r.into_cfglayout
-rw-rw-r-- 1 XXX XXX  3398 août  25 19:12 tmp0.f.195r.jump
-rw-rw-r-- 1 XXX XXX  1570 août  25 19:12 tmp0.f.207r.reginfo
-rw-rw-r-- 1 XXX XXX  1634 août  25 19:12 tmp0.f.225r.outof_cfglayout
-rw-rw-r-- 1 XXX XXX  1601 août  25 19:12 tmp0.f.226r.split1
-rw-rw-r-- 1 XXX XXX  2980 août  25 19:12 tmp0.f.228r.dfinit
-rw-rw-r-- 1 XXX XXX  3062 août  25 19:12 tmp0.f.229r.mode_sw
-rw-rw-r-- 1 XXX XXX  2980 août  25 19:12 tmp0.f.230r.asmcons
-rw-rw-r-- 1 XXX XXX  6631 août  25 19:12 tmp0.f.234r.ira
-rw-rw-r-- 1 XXX XXX  5581 août  25 19:12 tmp0.f.235r.reload
-rw-rw-r-- 1 XXX XXX  3299 août  25 19:12 tmp0.f.238r.split2
-rw-rw-r-- 1 XXX XXX  4347 août  25 19:12 tmp0.f.242r.pro_and_epilogue
-rw-rw-r-- 1 XXX XXX  3957 août  25 19:12 tmp0.f.245r.jump2
-rw-rw-r-- 1 XXX XXX  4007 août  25 19:12 tmp0.f.258r.stack
-rw-rw-r-- 1 XXX XXX  3925 août  25 19:12 tmp0.f.259r.alignments
-rw-rw-r-- 1 XXX XXX  3513 août  25 19:12 tmp0.f.261r.mach
-rw-rw-r-- 1 XXX XXX  3513 août  25 19:12 tmp0.f.262r.barriers
-rw-rw-r-- 1 XXX XXX  3578 août  25 19:12 tmp0.f.266r.shorten
-rw-rw-r-- 1 XXX XXX  3578 août  25 19:12 tmp0.f.267r.nothrow
-rw-rw-r-- 1 XXX XXX  4216 août  25 19:12 tmp0.f.268r.dwarf2
-rw-rw-r-- 1 XXX XXX  3578 août  25 19:12 tmp0.f.269r.final
-rw-rw-r-- 1 XXX XXX  2387 août  25 19:12 tmp0.f.270r.dfinish

What are these files, and can I avoid their production with some nice option passed to gfortran ?

Answer 1

Dynamic libraries (.dylib) are for your mac. On Linux, we use shared libraries (.so) and your compile command should omit the -dynamiclib, which your warning told you was not understood. I would also drop the -m32 unless you have a specific need for 32 bit code.

gfortran-5.2.0 -fPIC -shared ./tmp0.f -o ./tmp0.so

Will build your library properly. If you keep it in your build directory you'll also need to let the dynamic linker where it is, either by using the LD_LIBRARY_PATH environment variable or using the -rpath linker option to the eventual binary you link this to, to encode the library path into the executable.

That mess of files you wound up with are from the interpretation of -dynamic by gcc. It interpreted the it as -da (and warned you about not understanding the rest). The -d option causes GCC to emit debugging dumps during compliation and the a says to emit all of them. You can delete them all and they won't be output with the command line given above.