[fedora-arm] On ARM atomics

[Michael Hope]

On 14 November 2012 06:21, Jon Masters <jcm at redhat.com> wrote:
> On 11/13/2012 01:24 AM, Nicolas Pitre wrote:
>
>> There are several serious mistakes in your assembly example.
>
> Thanks for the feedback! Appreciated. Comments below...
>
>> |START_FUNC(opal_atomic_add_32)
>> |       push    {r4-r7}
>>
>> Why r4 to r7?  You're using only r4 below.
>
> Ah. Because in the rest of the OpenMPI code they're doing similar on
> function entry (saving all 4 of the variable registers). You're right
> that I only use one of those registers so I could have not bothered to
> save all 4 of them.

Random note: you need to save an even number of registers to keep the
stack aligned to eight bytes.  Nico's code below is good.

-- Michael