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Re: [TESTCASE] Minimized testcase for AltiVec segfault
- From: Geoff Keating <geoffk at geoffk dot org>
- To: aldyh at redhat dot com
- Cc: kumar dot gala at motorola dot com, degger at fhm dot edu, gcc at gcc dot gnu dot org, dje at watson dot ibm dot com
- Date: Thu, 28 Feb 2002 17:34:46 -0800
- Subject: Re: [TESTCASE] Minimized testcase for AltiVec segfault
- References: <25CE0F90-2C9A-11D6-87D4-000393750C1E@redhat.com>
- Reply-to: Geoff Keating <geoffk at redhat dot com>
> Date: Fri, 1 Mar 2002 09:26:02 +1100
> Cc: kumar.gala@motorola.com, degger@fhm.edu, gcc@gcc.gnu.org,
> dje@watson.ibm.com
> From: Aldy Hernandez <aldyh@redhat.com>
>
> > Why can't varargs and vector arguments be supported under the SVR4
> > ABI?
>
> because things won't be aligned properly. and if they were,
> we'd no longer be SVR4 abi compliant.
Can you explain what doesn't get aligned? SVR4 always had 16-byte
stack alignment (unlike some other ppc ABIs).
> > Isn't altivec still useful even if you can't pass vectors as
> > arguments?
>
> sure, but we don't need a flag to do that.
But we do! We need a flag to tell the compiler _not_ to use altivec
instructions for block copies, for example, on non-altivec chips.
--
- Geoffrey Keating <geoffk@geoffk.org> <geoffk@redhat.com>