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Re: (C++) mangling vector types
- From: Mark Mitchell <mark at codesourcery dot com>
- To: Richard Henderson <rth at redhat dot com>
- Cc: Jason Merrill <jason at redhat dot com>, GCC <gcc at gcc dot gnu dot org>, Ulrich Drepper <drepper at redhat dot com>
- Date: Thu, 12 Nov 2009 10:18:16 -0800
- Subject: Re: (C++) mangling vector types
- References: <4AFC28C8.6090505@redhat.com> <4AFC3365.3050200@redhat.com>
Richard Henderson wrote:
> On 11/12/2009 07:24 AM, Jason Merrill wrote:
>> 1) Leave the current mangling as is
>> 2) Leave the current mangling as is for the most common vector size on a
>> target (SSE, Altivec) and use the new mangling for other vector sizes.
>> 3) Switch to the new mangling
>
> I vote for 2.
Me too. Never break backwards compatibility unless really necessary.
We might want to note these special cases in the actual ABI document,
since my impression is that most other compilers are trying to follow G++.
>> b) Take over -fabi-version=3 and bump the template arg change to v4.
I'm not sure what "take over" means, but I think this change should be
in v4. People might be using v3, and we shouldn't break their world.
Introducing 2.1, or a separate flag, seems odd to me; there's nothing
particularly more or less different about this change then other
mangling changes, as far as I can tell. It's another case where we've
discovered an inability to implement the full language with the current
scheme, and have therefore been forced to make a change.
--
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713