This is the mail archive of the
mailing list for the GCC project.
Re: [TESTCASE] Minimized testcase for AltiVec segfault
- From: Dale Johannesen <dalej at apple dot com>
- To: Aldy Hernandez <aldyh at redhat dot com>
- Cc: Dale Johannesen <dalej at apple dot com>, Kumar Gala <kumar dot gala at motorola dot com>, Daniel Egger <degger at fhm dot edu>, GCC Developer Mailinglist <gcc at gcc dot gnu dot org>, David Edelsohn <dje at watson dot ibm dot com>, Geoff Keating <geoffk at geoffk dot org>
- Date: Thu, 28 Feb 2002 14:28:45 -0800
- Subject: Re: [TESTCASE] Minimized testcase for AltiVec segfault
On Wednesday, February 27, 2002, at 09:40 PM, Aldy Hernandez wrote:
> On Thursday, February 28, 2002, at 02:49 PM, Dale Johannesen wrote:
>> On Wednesday, February 27, 2002, at 07:38 PM, Kumar Gala wrote:
>>> That would be good (on LinuxPPC the default should be for vrsave to be
>>> disabled). I am not sure how register allocation is handled on darwin/
>>> MacOS-X ABI. Maybe one of the Apple guys can pipe up, Stan? My guess
>>> would be that it does not differ much from how it is handled on MacOS.
>>> (I could be wrong).
>> The usual lreg/greg algorithms are used; it's not necessarily in any
>> By prologue/epilogue generation time we know which Vregs were used in
>> the function.
>> If needed, the old value of VRsave is saved on the stack and VRsave is
>> ORed with
>> a mask indicating which regs are used in the function. This must be
>> done before
>> any Vreg is actually used. At epilogue the old VRsave is restored, and
>> this must
>> be after all Vreg uses. Interrupt handlers, context switch, etc. are
>> for saving/restoring whichever Vregs are indicated by VRsave, i.e. it is
>> to be up to date (or overly conservative) all the time. When
>> non-Altivec code
>> is running, VRsave will be 0, which means there's no save/restore
> in other words, it works exactly the same as for all the other ppc
> variants? :-)
Well, yes, but he did ask.