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List:       gcc-fortran
Subject:    Re: is there a way to find out gfortran version and/or options from a given binary?
From:       Kay Diederichs <kay.diederichs () uni-konstanz ! de>
Date:       2022-06-03 10:12:29
Message-ID: 5332f472-6188-aa8b-1d91-7c84ec265f0a () uni-konstanz ! de
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On 6/3/22 10:16, Janne Blomqvist via Fortran wrote:
> On Fri, Jun 3, 2022 at 10:30 AM Arjen Markus via Fortran
> <fortran@gcc.gnu.org> wrote:
> > 
> > Hi Kay,
> > 
> > (you forgot to reply to everybody ;))
> > 
> > I am using a Windows version of gfortran and strings. I use a file viewer
> > that comes with the Total Commander file manager. So, it may be something
> > specific to that version of strings.
> 
> One caveat being that Fortran strings are not NULL terminated like C
> strings. So a tool that searches for C-style strings in a binary might
> not find Fortran-style strings unless there happens to be a NULL after
> them for some other reason. The version of strings included in GNU
> binutils searches for strings terminated by any non-printable
> character, so it finds Fortran style strings (and a lot of noise which
> isn't strings).
> 
> > Op vr 3 jun. 2022 om 09:25 schreef Kay Diederichs <
> > kay.diederichs@uni-konstanz.de>:
> > > @Janne thanks for pointing out that -g does not make the code slower.
> > > Is there an option that prevents the sourcecode to be included when -g is
> > > used?
> 
> You might try -frecord-gcc-switches. There's also
> -grecord-gcc-switches (which puts the info somewhere in the debug
> data), which is enabled by -g, but without -g it seems it doesn't do
> anything.
> 

thanks for pointing at -frecord-gcc-switches . This appears to be what I was looking \
for. Googling for frecord-gcc-switches (without the leading "-", of course) brings up \
very interesting exchanges. For the record, when -frecord-gcc-switches  is used in \
compilation, objdump -s --section=.GCC.command.line <binary>
or
readelf -p .GCC.command.line <binary>
shows the compiler options.
I have not (yet) tried to find out how -grecord-gcc-switches differs, nor if and why \
the suggestion to "Introduce a new GCC option, --record-gcc-command-line" was \
rejected ( https://gcc.gnu.org/legacy-ml/gcc-patches/2019-11/msg00434.html ).

Thanks to all who responded!
Kay


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