gcc optimises out test of value in register-only loop

[Andrew Haley]

On 10/14/2011 05:41 AM, Ian Lance Taylor wrote:
> MikeW <mw_phil@yahoo.co.uk> writes:
> 
>>   volatile register int stop_loop __asm("r5")__;
> 
> gcc does not support volatile register variables.  I think it could be
> meaningful, but it has never worked.

It would be really nasty to implement: we'd have to check for volatility
on every access to a hard register.  The benefits don't seem worth it,
IMO.

Andrew.