This is the mail archive of the
mailing list for the GCC project.
Re: [RFC] Add aarch64 support for ada
- From: Tristan Gingold <gingold at adacore dot com>
- To: Richard Henderson <rth at redhat dot com>
- Cc: Eric Botcazou <ebotcazou at adacore dot com>, gcc-patches at gcc dot gnu dot org, bosch at gnat dot com, charlet at act-europe dot fr
- Date: Thu, 17 Apr 2014 11:00:53 +0200
- Subject: Re: [RFC] Add aarch64 support for ada
- Authentication-results: sourceware.org; auth=none
- References: <1397631733-10377-1-git-send-email-rth at redhat dot com> <3844044 dot G03Zse2hGV at polaris> <534EA364 dot 9080009 at redhat dot com>
On 16 Apr 2014, at 17:36, Richard Henderson <firstname.lastname@example.org> wrote:
> On 04/16/2014 12:39 AM, Eric Botcazou wrote:
>>> The primary bit of rfc here is the hunk that applies to ada/types.h
>>> with respect to Fat_Pointer. Given that the Ada type, as defined in
>>> s-stratt.ads, does not include alignment, I can't imagine why the C
>>> type should have it.
>> See gcc-interface/utils.c:finish_fat_pointer_type.
> Ah hah.
> /* Make sure we can put it into a register. */
> if (STRICT_ALIGNMENT)
> TYPE_ALIGN (record_type) = MIN (BIGGEST_ALIGNMENT, 2 * POINTER_SIZE);
> AArch64 is not a STRICT_ALIGNMENT target, thus the mismatch.
As the align attribute in types.h is for the host, couldn't a configure test solve
this issue ?
> If we were to make this alignment unconditional, would it be better to drop the
> code from here in finish_fat_pointer_type and instead record that in the Ada
> source, as we do with the C source?
> I presume
> for Fat_Pointer'Alignment use System.Address'Size * 2;
> or some such incantation would do that...
One of the most common Fat_Pointer is for strings, which aren't declared in any
source and is very commonly used.
OTOH, I think this optimization mostly targets sparc.