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Re: Still crashes due to aliasing violation (Re: [RFC, PATCH] Split pool_allocator and create a new object_allocator)
- From: "Ulrich Weigand" <uweigand at de dot ibm dot com>
- To: richard dot guenther at gmail dot com (Richard Biener)
- Cc: mliska at suse dot cz (Martin LiÅka), gcc-patches at gcc dot gnu dot org
- Date: Fri, 17 Jul 2015 18:54:32 +0200 (CEST)
- Subject: Re: Still crashes due to aliasing violation (Re: [RFC, PATCH] Split pool_allocator and create a new object_allocator)
- Authentication-results: sourceware.org; auth=none
Richard Biener wrote:
> On July 17, 2015 3:50:19 PM GMT+02:00, "Martin Liška" <mliska@suse.cz> wrote:
> >Question is why aliasing oracle still wrongly aliases these pointers?
> >Another option (suggested by Martin Jambor) would be to place
> >::allocate implementation
> >to alloc-pool.c file.
>
> Note that all compilers up to 4.4 have aliasing issues with placement new.
> A fix is to move the placement new out-of-line.
Yes, that's what I just noticed as well. In fact, my particular problem
already disappears with 4.3, presumably due to the fix for PR 29286.
So do we now consider host compilers < 4.3 (4?) unsupported for building
mainline GCC, or should we try to work around the issue (e.g. by moving
the allocator out-of-line or using some other aliasing barrier)?
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU/Linux compilers and toolchain
Ulrich.Weigand@de.ibm.com