This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: Enable TBAA on anonymous types with LTO
- From: Jason Merrill <jason at redhat dot com>
- To: Jan Hubicka <hubicka at ucw dot cz>, Richard Biener <rguenther at suse dot de>
- Cc: gcc-patches at gcc dot gnu dot org, ebotcazou at libertysurf dot fr, paul at codesourcery dot com
- Date: Tue, 30 Sep 2014 10:35:13 -0400
- Subject: Re: Enable TBAA on anonymous types with LTO
- Authentication-results: sourceware.org; auth=none
- References: <20140926191400 dot GB27278 at kam dot mff dot cuni dot cz> <alpine dot LSU dot 2 dot 11 dot 1409291019370 dot 20733 at zhemvz dot fhfr dot qr> <20140929153615 dot GB19673 at kam dot mff dot cuni dot cz>
On 09/29/2014 11:36 AM, Jan Hubicka wrote:
If C++ FE sets canonical type always to main variant, it should work.
Is it always the case?
No. For a compound type like a pointer or function the canonical type
strips all typedefs, but a main variant does not.
namespace {
struct B {};
}
struct A
{
void t(B);
void t2();
};
Yep, A seems to be not anonymous and mangled as A. I think it is ODR violation
to declare such type in more than one compilation unit (and we will warn on
it). We can make it anonymous, but I think it is C++ FE to do so.
Yes, it's an ODR violation. The FE currently warns about a field with
internal type, and I suppose could warn about other members as well.
I really think that anonymous types are meant to not be accessible from other
compilation unit and I do not see why other languages need different rule.
Agreed.
This does not work for types build from ODR types that are not ODR themselves.
I'm not sure what you mean. In C++ the only types not subject to the
ODR are local to one translation unit, so merging isn't an issue. Do
you mean types from other languages?
Jason