Re: [PATCH] Fix up ICEs with TREE_CONSTANT references (PR c++/78373)

[Jason Merrill <jason at redhat dot com>]

On Wed, Nov 16, 2016 at 4:00 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> Jason's recent patch to turn reference vars initialized with invariant
> addresses broke the first testcase below, because &self->singleton
> is considered TREE_CONSTANT (because self is TREE_CONSTANT VAR_DECL and
> singleton field has constant offset), but after going into SSA form
> it is not supposed to be TREE_CONSTANT anymore (&self_2->singleton),
> because SSA_NAMEs don't have TREE_CONSTANT set on them.
>
> The following patch fixes it by gimplifying such vars into their
> DECL_INITIAL unless in OpenMP regions, where such folding is deferred
> until omplower pass finishes.

Hmm, this seems like a workaround; why don't we see the same problem
with constant pointer variables?

A simpler workaround would be to not set TREE_CONSTANT on references
in the first place, since the constexpr code doesn't need it.  What do
you think?

Attachment: const-ref.diff
Description: Text document