> >struct A { char buf[64]; };
> >void foo (char *);
> >void test ()
> >{
> > { A a; foo (a.buf); a.buf[6] = 1; a.buf[7] = 8; }
> > { A a; foo (a.buf); a.buf[6] = 1; a.buf[7] = 8; }
> > { A a; foo (a.buf); a.buf[6] = 1; a.buf[7] = 8; }
> > { A a; foo (a.buf); a.buf[6] = 1; a.buf[7] = 8; }
> > { A a; foo (a.buf); a.buf[6] = 1; a.buf[7] = 8; }
> > { A a; foo (a.buf); a.buf[6] = 1; a.buf[7] = 8; }
> > { A a; foo (a.buf); a.buf[6] = 1; a.buf[7] = 8; }
> >}
> >where with your patch we don't DSE the a.buf[6] and a.buf[7] stores
> >anymore.
I see now.
> >
> >If optimize_clobbers isn't performed at -O0, perhaps we should consider
> >performing at at -O0 (just that and not the other EH optimizations)?
>
> Or, as clobbers are removed during rtl expansion make sure we remove empty eh
> stuff there?
Removing all the clutter that empty EH causes is quite a lot of work.
In Jakub's testcase we need to output clobber on the non-EH path
foo (&a.buf);
a.buf[6] = 1;
a.buf[7] = 8;
a ={v} {CLOBBER};
So I guess we can not modify giplifier to output
foo (&a.buf);
a.buf[6] = 1;
a.buf[7] = 8;
a = {CLOBBER};
instead of
try
{
foo (&a.buf);
a.buf[6] = 1;
a.buf[7] = 8;
}
finally
{
a = {CLOBBER};
}
Whenever A is just CLOBBER because we care about dead store over the possible
EH path?
I suppose this may make sense to do so even when this try...finally is toplevel
to aid
possible inlining. The clobbers on EH are however currently removed by
ehcleanup1 that
is before we do any DSE and inlining..
Of course I would not like to have empty EH statemetns with all the unwind
logic flying
trhough the inliner's code estimate logic or I will have to teach it to
anticipate
their removal.
Honza
