On Mon, Sep 19, 2022 at 9:31 AM Mikael Morin <[email protected]> wrote:
>
> Le 18/09/2022 à 12:48, Richard Biener a écrit :
> >
> >> Does *(&a[1]) count as a pointer dereference?
> >
> > Yes, technically.
> >
> >> Even in the original dump it is already simplified to a straight a[1].
> >
> > But this not anymore. The check can probably be relaxed, it stems from the
> > dual purpose of CLOBBER.
> >
> So the following makes the frontend-emitted IL valid, by handing the
> simplification over to the middle-end, but I can't help thinking that
> behavior won't be more reliable.
I think that will just delay the folding. We are basically relying on
the frontends to
restrict what they produce, the *ptr case was specifically for C++
this in CTOR/DTORs
and during inlining we throw away all clobbers that end up "wrong" but
I guess we
might have latent issues when we obfuscate the address in the caller enough and
get undesired simplification ...
>
> diff --git a/gcc/fortran/trans-expr.cc b/gcc/fortran/trans-expr.cc
> index f8fcd2d97d9..5fb9a3a536d 100644
> --- a/gcc/fortran/trans-expr.cc
> +++ b/gcc/fortran/trans-expr.cc
> @@ -6544,8 +6544,9 @@ gfc_conv_procedure_call (gfc_se * se, gfc_symbol *
> sym,
> && !sym->attr.elemental)
> {
> tree var;
> - var = build_fold_indirect_ref_loc (input_location,
> - parmse.expr);
> + var = build1_loc (input_location, INDIRECT_REF,
> + TREE_TYPE (TREE_TYPE
> (parmse.expr)),
> + parmse.expr);
> tree clobber = build_clobber (TREE_TYPE (var));
> gfc_add_modify (&clobbers, var, clobber);
> }
>
