On 13 February 2013 14:35, Johannes Pfau <nospam@example.com> wrote:

Am Wed, 13 Feb 2013 14:10:26 +0000
schrieb Iain Buclaw <ibuclaw@ubuntu.com>:

> On 13 February 2013 13:26, Johannes Pfau <nospam@example.com> wrote:
>

> > Am Tue, 12 Feb 2013 18:16:31 +0000
> > schrieb Iain Buclaw <ibuclaw@ubuntu.com>:
> >
> > > TREE_ADDRESSABLE should be sufficient.  I can't think any reason
> > > off the top of my head why not.
> > >
> >
> > maybe TREE_ADDRESSABLE is too strong: It generates errors in the
> > backend if the frontend produces non-lvalues:
> > ---
> >     auto b = Date();
> >     a(b);
> > ---
> >
> > works, but
> > ---
> >     a(Date());
> > ---
> >
> > fails in gimplify.c. Do we really have to rewrite such cases so that
> > non-PODs get a temporary variable? And how would this be done? It
> > seems we would have to use the frontend for this, as maybeMakeTemp
> > and makeTemp refuse to work for TREE_ADDRESSABLE types.
> >
>

> Don't set it on the variable, set it on the type.
>
> TypeStruct::toCtype()
> {
>     TYPE_ADDRESSABLE(ctype) = !isPOD();
> }

That's actually what I did. But the backend wants to create a copy of
the Date type which then fails as create_tmp_var fails for
TREE_ADDRESSABLE types.

Complete test case:
https://gist.github.com/jpf91/4944999

-----
../../objdir-4.7/x86_64-unknown-linux-gnu/libphobos/dm-test.reduced/datetime2.d:22:
internal compiler error: in create_tmp_var, at gimplify.c:479 0x804509
-----

Ahh, that's because of this piece of codegen:

SAVE_EXPR <*test.Date.this (&((void) (__ctmp971 = _D4test4Date6__initZ);, __ctmp971), 0)>

Gimple doesn't like the dereference in SAVE_EXPR.  This should work.

tree
IRState::makeTemp (tree t)
{
  tree type = TREE_TYPE (t);
  if (TREE_CODE (type) != ARRAY_TYPE && !TREE_ADDRESSABLE (type))
    return save_expr (t);

  return stabilize_reference (t);
}

So the generated code is now:

*SAVE_EXPR <test.Date.this (&((void) (__ctmp971 = _D4test4Date6__initZ);, __ctmp971), 0)>