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To: Andrew Cagney <ac131313@redhat.com>
cc: Richard.Earnshaw@arm.com, Kris Warkentin <kewarken@qnx.com>,
        gdb-patches@sources.redhat.com
Reply-To: Richard.Earnshaw@arm.com
Organization: ARM Ltd.
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Subject: Re: [rfa?] Add frame_align(); Was: ARM stack alignment on hand 
 called functions
In-reply-to: Your message of "Thu, 28 Nov 2002 11:45:17 EST."
             <3DE6481D.9060308@redhat.com> 
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Date: Thu, 28 Nov 2002 08:50:00 -0000
From: Richard Earnshaw <rearnsha@arm.com>
X-SW-Source: 2002-11/txt/msg00718.txt.bz2

> >> >> +/* 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
> 
> You mean ~(ULONGEST)0x7?
> 
> 

I mean ~(typeof(addr)) 0x7.

R.