[Bug fortran/79430] [7 Regression] action of statement incorrectly optimised away

["tkoenig at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79430

--- Comment #38 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
(In reply to Bijan Chokoufe from comment #37)
> (In reply to Thomas Koenig from comment #35)
> 
> > [tkoenig@gcc1-power7 shower]$ pwd
> > /home/tkoenig/whizard-2.4.1/src/shower
> > [tkoenig@gcc1-power7 shower]$ grep -i volatile *.f90
> > [tkoenig@gcc1-power7 shower]$ 
> > 
> > Did you run a diff on the generated assembly with and without
> > the VOLATILE statement?  You can use the -save-temps option for that.
> 
> I generated the .s files with -save-temps with and without volatile
> attributes. The diff is attached. I can say the instructions are different
> but that's about it.

I looked at the diffs, but for me also, nothing stands out.

> Concerning your PowerPC compilation: Have you set FCLAGS yourself

No, I didn't.; I just ran "./configure" and "make -j16".
This is why I suspect a target issue.  Of course, it could also
be that there are different inlining heuristics on PowerPC.

You could add "-m32" to the compiler flags; this would
build a 32-bit binary.  Obviously, you would have to rebuild
the whole source tree.  What does that do?

Additionally, if it is not possible to generate a smaller failing test case,
the next step would be to see which revision failed first.

What is the latest version of the compiler that still works?
Specifically, did you ever try this with an earlier version of
gcc 7 trunk?