Comment # 13 on bug 1133245 from Martin Li��ka

(In reply to Dr. Werner Fink from comment #12)
> (In reply to Martin Li��ka from comment #10)
> > (In reply to Dr. Werner Fink from comment #8)
> > > Hmm ... the transformation might be correcti(?), but how should libsigsegv
> > > catch the first segmentation fault (and only this), if the check is moved in
> > > the resulting assembler instructions out of the way?  Would the volatile
> > > attribute for handler_called help here?
> > 
> > I would recommend to use a memory barrier:
> > asm volatile("" ::: "memory");
> > 
> > More informations:
> > https://stackoverflow.com/questions/14950614/working-of-asm-volatile-memory
> > 
> > > 
> > > Btw: IMHO we need an HOWTO for debugging link time optimized programs within
> > > gdb. This because with LTO the core dumps from users/customers become rather
> > > useless (IMHO).
> 
> Ouch .. this is somehow a d��j�� vu for me as I had in past (15 years back)
> used memory barriers very often but had been told that this not need anymore
> with the modern gcc.
> 
> IMHO it is a bug of the compiler if code is moved in such a way that the
> logic becomes broken.

So that I created a GCC issue and let's be given a clarification:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90245