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Re: [rfa?] Add frame_align(); Was: ARM stack alignment on hand called functions
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Andrew Cagney <ac131313 at redhat dot com>
- Cc: Richard dot Earnshaw at arm dot com, Kris Warkentin <kewarken at qnx dot com>, gdb-patches at sources dot redhat dot com
- Date: Thu, 28 Nov 2002 16:32:55 +0000
- Subject: Re: [rfa?] Add frame_align(); Was: ARM stack alignment on hand called functions
- Organization: ARM Ltd.
- Reply-to: Richard dot Earnshaw at arm dot com
> >> +/* Ensure that the ARM's stack pointer has the correct alignment for a
> >> + new frame. */
> >> +static CORE_ADDR
> >> +arm_frame_align (struct gdbarch *gdbarch, CORE_ADDR addr)
> >> +{
> >> + return (addr & -16);
> >> +}
> >
> >
> > Yuck, two's complement assumption. I much prefer ~0xf in this case.
> >
> > But why so much. The maximum stack alignment you'll see on an ARM is 8
> > bytes.
>
> The function was lifted from the PPC code. And, hey, what's a few extra
> bytes between friends? :-)
>
> Does (addr & 0x7) look better?
>
> Andrew
>
>
As discussed elsewhere, the best solution (IMO) is
~(CORE_ADDR)0x7
R.