On Tue, May 30, 2023 at 10:03:05AM +0200, Eric Botcazou wrote:
> > We want to be able to treat such things as invariant somehow even if we
> > can't do that for references to user data that might be changed by
> > intervening code.
> >
> > That is, indicate that we know that the _REF actually refers to a const
> > variable or is otherwise known to be unchanging.
> >
> > Perhaps that should be a new flag that tree_invariant_p can check
> > instead of TREE_READONLY.
>
> Richard earlier suggested a langhook; given that Ada will be the main (sole?)
> user of it, this would probably be better.
Are the DECL_INVARIANT_P FIELD_DECLs in Ada really invariant no matter how
exactly they are accessed? Or can Ada suffer from the same problem as
C/C++, where the FIELD_DECL is TREE_READONLY, but could go out of scope or
a pointer to it could change.
I mean the p->fld cases in C/C++, where there could be free (p); or p++
etc. in between the place where save_expr is first evaluated and later
uses?
Jakub
