[AVR] Fix target/34888

[Georg-Johann Lay]

Richard Henderson wrote:
> On 08/04/2011 09:04 AM, Denis Chertykov wrote:
>> Thank you for explanation.
>> I have a very clean understanding of whole picture.
>> May be better to use define_peephole2 with 3 insns as input and 1 as
>> output for easy understanding.
> 
> *shrug* Maybe.  Then you also have to check for whether TMP
> is dead.  It just seemed tidier to me to let DCE do its job.
> 
> 
> r~

If it's just for understanding, simply add comments!
Comments in the source explaining what's going on is
always appreciated.

Johann