Re: [s390] increase stack alignment

["Andrew Pinski" <pinskia at gmail dot com>]

On Wed, Oct 8, 2008 at 1:55 PM, DJ Delorie <dj@redhat.com> wrote:
>
>> So could you please elaborate why you think this is necessary.
>
> The CDSG opcode needs 16 byte alignment when accessing stack
> variables, currently it doesn't get it, I'm not really picky about how
> it gets fixed ;-)
>
> In the test case I have (from a customer), the cdsg opcode is in an
> inline asm, so gcc can't know that that stack is "special".  However,
> the variables on stack are tagged for 32-byte alignment, and only get
> 8-byte alignment.  Perhaps something in gcc could note when stack
> variables need greater alignment than the stack normally provides, and
> adjust the stack at runtime accordingly?

See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16660.  I had posted a
patch which realigned the stack variables if needed but it was not
commented on except by HJL.  Intel implemented something different for
x86 where they realign the whole stack.

Thanks,
Andrew Pinski