On Mon, Jul 20, 2026 at 04:34:57PM -0400, Jason Merrill wrote:
> On 7/20/26 1:00 PM, Marek Polacek wrote:
> > On Tue, Jul 14, 2026 at 11:35:04PM -0400, Jason Merrill wrote:
> > > On 7/14/26 7:06 PM, Marek Polacek wrote:
> > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/16?
> > > >
> > > > -- >8 --
> > > > Like in PR110822, the attached test produces an ICE in verify_address:
> > > >
> > > > error: constant not recomputed when 'ADDR_EXPR' changed
> > > >
> > > > since r10-7718, but it wasn't fixed by r15-7762. The reason is that
> > > > here we have:
> > > >
> > > > {.D.3013={.D.3006={.a={.ptr=&<retval>.D.3013.D.3006.a}},
> > > > .D.3007={.b={.ptr=&<retval>.D.3013.D.3007.b}}}}
> > > >
> > > > and we replace '<retval>' with 'names', but we only call
> > > > recompute_tree_invariant_expr for the first ADDR_EXPR, not the latter.
> > > > For the second ADDR_EXPR d->changed will be false: the first replacement
> > > > changed the shared tree <retval>.D.3013. So I'm afraid we have to
> > > > recompute the flags unconditionally. It may be a bit slower, but it's
> > > > correct.
> > >
> > > OK for 16.
> > >
> > > But how do we end up with this sharing? It looks like
> > > replace_placeholders_r properly does unshare_expr.
> >
> > There are no PLACEHOLDER_EXPR so the unshare_expr in replace_placeholders_r
> > won't take place.
>
> Surely there's a PLACEHOLDER_EXPR created and replaced at some point for
> changing the 'this' in the DMI for bug::ptr to the two addresses above? If
> not, how does it happen?
True, once we're done with check_return_expr, we do have an expression
with PLACEHOLDER_EXPRs:
TARGET_EXPR <D.3018, {.D.3013={.D.3006={.a={.ptr=&<PLACEHOLDER_EXPR struct
bug>}}, .D.3007={.b={.ptr=&<PLACEHOLDER_EXPR struct bug>}}}}>
but they are replaced in cxx_eval_constant_expression/PLACEHOLDER_EXPR
when we call maybe_constant_value on the ctor containing them. When
we get to replace_placeholders it's been changed to
{.D.3013={.D.3006={.a={.ptr=&names.D.3013.D.3006.a}},
.D.3007={.b={.ptr=&names.D.3013.D.3007.b}}}}
store_init_value has a call to fold_non_dependent_expr
and does
/* Handle aggregate NSDMI in non-constant initializers, too. */
value = replace_placeholders (value, decl);
only after it.
Marek
