This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [RFA wwwdocs] Re: [PATCH v2] Target-specific limits on vector alignment
- From: "Ulrich Weigand" <uweigand at de dot ibm dot com>
- To: rearnsha at arm dot com (Richard Earnshaw)
- Cc: ramana dot radhakrishnan at linaro dot org (ramana dot radhakrishnan at linaro dot org), richard dot guenther at gmail dot com (Richard Guenther), gcc-patches at gcc dot gnu dot org (gcc-patches at gcc dot gnu dot org)
- Date: Fri, 10 Aug 2012 17:18:03 +0200 (CEST)
- Subject: Re: [RFA wwwdocs] Re: [PATCH v2] Target-specific limits on vector alignment
Richard Earnshaw wrote:
> On 10/08/12 14:44, Ulrich Weigand wrote:
> > Would the following htdocs patch be OK with you? Feel free to suggest
> > a more appropriate wording ...
>
> I think we need to make it clear that this also fixes a bug in the
> compiler that could lead to a run-time error. Otherwise, people will be
> asking why an abi-breaking change was made mid-cycle.
Something along the following lines?
<p>The default alignment of vector types on ARM EABI targets has been changed
to 8 bytes (for types larger than 8 bytes in size). This change was necessary
in order to fix a bug that could lead to generation of wrong code in certain
cases. It also brings the ABI as implemented by GCC back in compliance with
the AAPCS. This is an ABI change that affects e.g. layout of structures having
a member of vector type. Code using such types may be incompatible with binary
objects built with older versions of GCC.</p>
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU Toolchain for Linux on System z and Cell BE
Ulrich.Weigand@de.ibm.com