https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118120
--- Comment #9 from anlauf at gcc dot gnu.org ---
(In reply to kargls from comment #8)
> (In reply to anlauf from comment #7)
> > The following patch works and might be a reasonable compromise:
> >
> > diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
> > index 82a2ae1f747..985a26281ad 100644
> > --- a/gcc/fortran/trans-array.cc
> > +++ b/gcc/fortran/trans-array.cc
> > @@ -5345,7 +5345,10 @@ symbols_could_alias (gfc_symbol *lsym, gfc_symbol
> > *rsym, bool lsym_pointer,
> > bool lsym_target, bool rsym_pointer, bool rsym_target)
> > {
> > /* Aliasing isn't possible if the symbols have different base types. */
> > - if (gfc_compare_types (&lsym->ts, &rsym->ts) == 0)
> > + if (!gfc_compare_types (&lsym->ts, &rsym->ts)
> > + && !(((lsym->ts.type == BT_COMPLEX && rsym->ts.type == BT_REAL)
> > + || (lsym->ts.type == BT_REAL && rsym->ts.type == BT_COMPLEX))
> > + && lsym->ts.kind == rsym->ts.kind))
> > return 0;
> >
> > /* Pointers can point to other pointers and target objects. */
>
> I think it is more complicated in that this involves pointers, which
> have an aliasing issue (due to bounds remapping). In an ordinary assignment
> one has 'var = expr', and in Slava example that is exactly what we have
> where 'result' and 'temp' are pointers into parts of 'data%re'. But,
> 'data%re' could have been any type compatible entity. The big hammer,
> until the mythical someone shows up, is
>
> diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
> index 82a2ae1f747..abebf327621 100644
> --- a/gcc/fortran/trans-array.cc
> +++ b/gcc/fortran/trans-array.cc
> @@ -5503,6 +5503,20 @@ gfc_conv_resolve_dependencies (gfc_loopinfo * loop,
> gfc_ss * dest,
> loop->temp_ss = NULL;
> dest_expr = dest->info->expr;
>
> + /* Before falling into dependency checking of the scalarization,
> + check to see if the left-hand variable is an array pointer. If
> + it is, simply generate an array temporary for the assignment.
> + TODO: walk the right-hand-side of 'var = expr' to actually check
> + for a dependency. See 118120. */
> + if (dest_expr->symtree && dest_expr->symtree->n.sym
> + && dest_expr->symtree->n.sym->attr.pointer
> + && dest_expr->symtree->n.sym->attr.dummy
> + && dest_expr->symtree->n.sym->attr.dimension)
> + {
> + nDepend = 1;
> + goto temporary;
> + }
> +
> for (ss = rss; ss != gfc_ss_terminator; ss = ss->next)
> {
> ss_info = ss->info;
I doubt that this is a good solution.
It is completely irrelevant that "result" is a dummy. Just try it.
And creating a temporary for *every lhs pointer* cannot be acceptable.
There must be something more "lightweight".
