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Re: [PATCH 1/2][ARM] PR/65956 AAPCS update for alignment attribute
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: Alan Lawrence <alan dot lawrence at arm dot com>
- Cc: gcc-patches at gcc dot gnu dot org, Jakub Jelinek <jakub at redhat dot com>, Ramana Radhakrishnan <ramana dot radhakrishnan at foss dot arm dot com>, Richard Earnshaw <Richard dot Earnshaw at foss dot arm dot com>, fweimer at redhat dot com
- Date: Fri, 27 Nov 2015 18:55:34 +0100
- Subject: Re: [PATCH 1/2][ARM] PR/65956 AAPCS update for alignment attribute
- Authentication-results: sourceware.org; auth=none
- References: <5596A98A dot 7080500 at arm dot com> <CAOckXuNpQ8NF+9YeEaTkKj9K+ROrpgVeVZ_sfMiA1_QNk=1AGQ at mail dot gmail dot com> <CAOckXuNSqMo7Z=x0ME=m55ydigGPOiDGaBpj-Mpj2J_vdQXhhQ at mail dot gmail dot com>
> So, I'm not familiar with Ada 'fat pointers' but if that is one -
> well, it's a record, with an alignment that the 'new' AAPCS now
> ignores, so yes the ABI has changed between gcc 5.1 and 5.2, rather
> more significantly for Ada than for C.
Yes, XUP suffixed types are fat pointers and they are maximally aligned so
that they can be given non-BLK mode and, consequently, live in registers.
> Thoughts?
There is no official ABI for Ada so I guess that's not really a problem as
long as it's documented on https://gcc.gnu.org/gcc-5/changes.html.
--
Eric Botcazou